机械工程英语叶邦彦汉语翻译第二部分

第一篇：机械工程英语叶邦彦汉语翻译第二部分

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PART 2 Unit 2 生产设备的数字控制

（1）数控是程序控制的自动化，在数字控制系统中，设备通过数字，字母和符号来编码，以一种合适的格式为每一个特定的零件或工件定义一个程序指令集。当工件变化时，程序也变化，改变程序的能力也就是适合中小批量生产。写一个新程序比改变大量生产设备要容易的多。

（2）基本结构：数控系统由下面三部分组成：1.控制程序；2.机器控制单元；3.加工设备。

三部分的基本关系，由图2.1所示。程序输入到控制单元由送入的程序来引导加工设备控制。

（3）指导程序是一步步详细的指导加工设备的指令。通常指令把主轴上刀具相对于安装工具的工作台定位。更多先进的说明包括主轴的转速，加工工具的选择及其功能。程序刻在合适的介质中，提交到机器控制单元中，在过去几十年中，最常用的介质是一英寸宽的打孔纸带。由于打孔纸带的广泛使用，NC有时也叫纸带控制，然而这是现代数控使用的误称。现在进入使用更多的是磁带和软盘。

（4）机器控制单元（MUC）由电子和控制硬件组成，机器控制单元可以读出和执行指令程序，可以自动改变加工工具和其他加工设备。

（5）执行单元是数控系统的第三基础部分，执行原件是有效执行工作的原件，最常见的数控例子其中的一个加工操作，加工设备由工作台和主轴组成，就像用电动机来驱动一样。加工设备由控制单元来驱动控制系统的类型。控制系统的类型

（6）数控有2种基本类型，点对点式和轮廓式控制，点对点式控制也称定位控制，每个轴都是通过丝杠单独驱动，根据加工类型不同，加工速度也不一样。机器开始以最大速度运行来减少非加工时间，但当他达到数据定义的位置时，机器开始减速。因此在一个操作中，如钻或冲孔操作先定位在加工。在钻或冲孔之后，迅速收起工具移动到另一个位置重复此操作。从一个位置移到另一个位置是非常重要的，要遵循一个原则，从效率上考虑只要时间最短即可。点对点系统主要用于钻，冲孔，直铣操作中。

（7）轮廓式也就是连续路径式系统，定位和切削同时按不同速度来控制，由于刀具在指定路线运动同时切削，因此速度和运动的同步控制是非常重要的。轮廓式系统常用于车床铣床磨床焊接设备和加工中心。

（8）沿着路径的运动或以增量差补是几个基本方式的一个，在所有的差补中，要控制刀具的回转中心定位，补偿可以以不同直径及刀具磨损，在数控程序中进行改写。

（9）有一些已形成差补方案来处理数控系统中连续路径和加工系统产生的问题包括：

1.线性差补；2.圆弧差补；3.螺旋线差补；4.抛物线差补；5.立体差补

（10）每一种差补程序都允许程序源产生加工指令，适用于相对少的输入参数的直线或曲线路径。储存在数控单元中的模块预算指引工具沿计算出的路径运动。

（11）线性差补是最基本的差补方法，用于连续路径的数控系统中。两轴和三轴线性差补路线在实际中有时会分辨出的，但在概念上他们是一样的，程序源要明确指定直线的起点和缺点及沿直线的进给率。差补需计算两轴或三轴的进给速率以达到设定的进给速度。

（12）线性差补用来差补圆是不合适的因为程序源需要明确指定线段部分（线段数量）和各自的终点来大约模拟圆弧。圆弧差补法已形成他允许程序编程的路径，使用圆弧只要给定以下参数，圆弧终点坐标，圆心坐标，半径和刀具沿圆弧路径的走刀方向。圆弧差补也是由许多小的直线段来实现的，但这些小线段的参数由差补模块来计算出来的，而不是程序员设定的。切削是沿着每一小线段一个一个的进行以产生光滑曲线路径。圆弧差补的局限性是圆弧路径所在平面是由数控系统中两轴所决定的平面。（13）螺旋线差补结合了环形差补两轴在第三轴上做线性运动这样来定义空间三维螺旋路径。

（14）抛物线差补和立方差补法通过高次高程来实现自由曲线。这通常需要有强的计算能力，正因如此，他不如直线差补和环形差补常见。他们主要用于汽车工业中具有自由风格的车身面，而这是线性差补和圆弧差补不能精确容易得到的。

（15）数控技术运用于数控机床，这是数控的主要应用。现在主要用于商业。我们仍讨论数控系统特别是金属数控车床。数控车床技术

（16）种加工过程都可以在设计的专门车床上来实现加工。在车床上车削，在钻床上钻，在铣床上加工。有几种类型的磨削方法也要有相应种类的磨床。被设计的数控磨床可以进行下列加工包括：1.钻加工；2.铣床立式和卧式主轴；3.车床卧式主轴和立式主轴；4.卧式和立式镗床；5.仿形铣床；6.平面磨和圆柱磨

（17）除了上述几种机械加工方法，数控机床可用于其他金属加工过程包括：用于薄片板的金属板上冲孔的冲压机，用于薄片金属

弯曲的折弯机。

（18）数控技术的介入到机加工对机床的设计和运用有着显著的影响。数控影响之一在程序控制下切削金属的时间与传统手动机床大得多。所以对于一些零件如主轴驱动主轴丝杠磨损更快，这些零件要设计成持续时间长的。第二，增加电子控制单元后设备成本也随之增加，因此需要更高的利用率。取代传统手工操作的一班制，数控机床通常采用两班或三班制来获得更多的回报。数控机床的设计中减少了非操作过程的时间如装卸工件和换刀时间。第三，增加的劳动成本由人工成本变为设备成本。考虑到人工操作的角色，角色由技术熟练的工人控制，工件生产的每一个过程变为只控制装卸换刀和清除碎屑和类似的操作，这样一个工人可以同时操作两台或三台车床，机床的角色和功能也改变了。数控需要设计成高度自动化具有需要在不同车床加工几种操作联合在一起一定加工的能力，这些变化是通过一种新型车床在数控技术存在之前是不存在的，他丰富了数控加工中心

（19）加工中心是在20世纪50年代发展起来的具有在程序控制下在一个工件上一次裝夹完成几种不同的加工能力的机床。加工中心能完成铣，钻，铰屑，攻丝，镗，车端面及一些类似机加工工作。另外数控加工中心的典型特征包括以下方面：

（20）(1)自动换刀能力: 多种机加工工作一位着需要多种刀具。刀具贝安装在刀库或多刀刀库中。当一把刀需要被调换时，多刀刀座自动旋转到相应的位置上。自动化的换刀机构。在程序控制下进行，把主轴上需换下的刀和多刀刀座上的刀调换。（21）(2)工件的自动定位: 大多数加工中心都可以使工件沿着主轴旋转因此允许刀具达到工件的四个表面。

（22）(3)托架滑动装置（平板架）: 加工中心另一个特点是有两个或多个独立拖板每个拖板都可以调整在刀具上。在加工过程中，一个拖板在刀具的前部，另一个拖板在远离主轴的安全位置。这样当机床正在加工当前的零件时。操作人员就可以从上一个工作循环中卸下最终加工好的零件，同时加紧毛坯用于下一个工作循环。

（23）加工中心可以分为立式和卧式。这是参照机床主轴方向来划分的。立式加工中心具有轴线相对工作台垂直的主轴，卧式车床的主轴轴线是水平方向的。这种区别通常会导致在这些加工中心加工的零件类型不同。立式加工中心用于以上进刀的平面工作。卧式加工中心用于立体形状，刀具在立体侧面可以进刀。一台数控卧式加工中心，例子如图2.2所示，具有上面提到的一些特征。（24）加工中心的成功应用导致了其他类似金属加工机床的发展。例如：在车削中心，把车削加工设计成一个高度自动化万能机床可以完成车削，刨，钻，螺纹加工和类似的操作 DNC AND CNC（25）数控的发展在分批生产和小批量生产中有着重要意义，从技术和商业角度来说都有着重要意义。数控有两方面的提高和扩展，包括：1.直接数据控制；2.计算机数字控制（26）直接数据控制

直接数据控制定义为一个制造系统，一定数量的机床有一台计算机通过直接硬件连线实时控制。相应的磁带播放机忽略在直接数控中，这样就消除系统中最不可靠的环节。不用磁带播放机而用电脑信息传给车床。原则上说一台计算机可以控制100台独立机器（DNC系统在1970年称为可控制26台机床）直接数控（DNC）电脑设计成在需要的时候提供指令给每一台机床，当机床需要控制指令时，计算机立即发送指令给机床。

（27）图2.3说明了DNC的基本配置。这个系统包括4部分：

1.中央计算机；2.大量内存，用于存放数控程序；3.通信线；4.机床刀具

（28）计算机从海量内存中取出部分程序指令送入到需要的独立机床中。相应的计算机也接受机床反馈信息。这种双工的信息流在实时控制加工系统中出现意味着每台机床需要指令的请求能立即得到回应。类似的，计算机必须总是要准备要接受信息和进行回应。DNC系统显著特点是：可以实时控制大量机床。更具机器数量和所需的计算机程度化。有时需要使用卫星计算机如图2.4所示。卫星计算机是更小的计算机，可以分担中央计算任务，减轻其负担。每台卫星控制几台机床。零件加工指令程序由计算机接受，储存在内存中。当需要时卫星计算机发送指令程序到每个独立机床中。来自机床的反馈数据在电脑中央存储接受之前存储在卫星内存中。（29）计算机数字控制

由于DNC技术的介入，在计算机技术上得到了很大的发展。计算机在尺寸和成本显著减少的同时，计算机的能力却有很大的提高。在数控中，这些发展使得由硬件布置的MCU（）变为数字电脑控制的控制单元。最早，小型机在1970年使用。随着计算机进一步小型化，小型机被当今的微型机取代。

（30）计算机控制也是一种数字控制，它采用微型计算机作为控制单元。由于数字电脑用于CNC 和DNC中，只近似区分两种类型。有三个区分原则：

1）.DNC电脑接受和发送指令数据都是来自许多机器，CNC电脑控制只是一个机器或多个机器。2）.DNC电脑占有一个位置通过控制来实现机器的旋转。CNC电脑要非常靠近车床。

3）.DNC软件的发展不经可以控制生产设备的每个单独零件，还可以在生产坚固性方面提供主要控制信息。CNC的提高可以提高特殊车床的能力。

（31）电脑数控系统的大体配置如图2.5所示。如图中所示，最初进入控制器的是磁带播放机。这样，CNC的外部系统与传统的NC机相似。然而CNC中的程序使用方法是不同的。

PART 2 Unit 4 机加工与切削加工中心

（1）这篇文章介绍了计算机控制的机械刀具设计的能力和较大的发展，就想我们知道的机加工和切削加工中心，这些机器有其他机器工具没有的柔性和多功能性，应此他们作为加工工具第一选择。机加工与切削加工中心

（2）需要注意的是每台机器他的自动化程度有多高，都要设计一种基本的加工样式就像所展示的那样，在制造过程中不同的表面是用不同的加工方法加工的，（3）例如，如图4.3所示，铣、端面车削、镗、钻、铰孔、切丝来获得额定的公差要求及最终表面精度。

（4）习惯性的加工过程的执行，始于工件的移动从一把加工刀具到另一把加工刀具直至所有的加工完成，这是一种切实可行的制造方法，并具有高度的自动化。这就是生产流水线的原理。最常见的是应用于高容量或大批量的生产，生产流水线是由几种加工刀具按一定的次序排列组成的，诸如自动发动机模块这样的工件从一个加工地点到另一个加工地点，并且在每一个加工中心都运用特有的加工方式进行加工，工件会被输送到下一个机器进行下一个加工。

（5）有这样一些产品或加工方法，他们的生产路线是不可行或不经济的，特别是当这些种类的产品在加工时需要迅速转换加工方法。一个重要的概念，在20世纪50年代末期得到发展，那就是机加工中心。一个机加工中心就是运用计算机控制的刀具在工件的不同表面和不同的方向上进行切削操作的能力，通常说工件是不动的，而切削工具进行旋转，比如铣和钻操作。

（6）机加工中心的发展暗示着计算机控制的机器刀具之间关系的进步。如数字控制的车床加工中心拥有两个转台带动几把切削刀具进行车削，端面车削，镗孔和切螺纹。

（9）加工中心装备了可变程序的自动刀具变换器，依赖于这样的设计多达200把切削刀具能够被贮存在刀库，刀鼓，刀链（工具库），辅助工具库能够更好的为一些特殊加工中心提供更好的切削道具，这些刀具可以自动的任意选择到达机械主轴的最短路线，刀具交换臂是一个普通的设计机构，他可以旋转来拾取特殊的工具（每一个工具有他自己的刀杆）和他在主轴上的位置。（10）刀具通过直接连接在刀具夹持口上的编码标签、条形码或记忆芯片来标识。一次换刀时间在5-10秒钟，对于小的刀具可以少于1-2秒，对于重达110公斤的刀具可以达到30秒，刀具变换器的设计趋势趋向于运用简单的原理提高换刀的时间。

（11）加工中心同时装备有工具的检验台，他可以给计算机数字控制提供信息对于在换刀和刀具磨损时的误差提供补偿。接触试探针可以自动装入工具夹持口中以确定工件的参考平面，以便对刀具设置进行选择并对加工的工件在线检测。

（12）图4.6所示的一些表面可以被联系起来，他们的相对位置可以被确立并储存在计算机软件的数据库中，这些数据稍后可被用于编写刀具工作路径的程序同时对刀具的长度和直径进行补偿，又可以为预先加工刀具的磨损提供补偿。机加工与切削加工中心的种类

（13）尽管这里有不同种类的刀具设计在加工中心中，两种最基本的种类垂直主轴和水平主轴；大部分的机器拥有上述两种轴线的能力，在加工中心中最大的切削刀具的尺寸可以绕工具一周，就像我们知道的工具包络，这个术语第一次应用在与工业机器人的联系上。

（14）垂直主轴加工中心或是水平主轴加工中心都是为了适用在工件具有深腔的平面上执行加工工艺，如铸型和模具制造。一个垂直主轴的加工中心类似于一个垂直主轴铣床。刀库在图示的左侧并且所有的加工方法和传动机构通过位于右侧的计算机控制托盘进行定位和修改。

（15）因为在加工中心中由于推力的作用方向是向下的，机器具有高的刚度，并在对于加工部分有较好的精确补偿，这些机器通常比水平主轴的机器便宜些。

（16）水平主轴的加工中心或水平机加工中心是为了适用于高大工件的表面加工的需求。托盘可以在不同的轴线（如图4.3所示）上旋转来进行不同种类的有角定位。

（17）水平主轴加工的另一个范畴是车削加工，是用特殊机床进行计算机控制的车削加工。一个三转动架的计算机数字控制的车削加工如图4.8所示，这个机器是由两个水平主轴和三个转动架以及不同的切削刀具设计而成的来执行一些旋转工件的加工。

（18）万能加工中心同时装备了垂直主轴和水平主轴的机器，他们具有不同种类的特色，并且具有加工所有表面的能力（垂直的、水平的、斜的）。机加工中心的特征和能力

（19）下面是加工中心的大部分特征：

a．他们有能力有效的，经济的并且拥有重复的高精度的尺寸的能力来处理不同型号的磨具的能力。公差的范围在正负0.0025mm。b．这些机器是万能的，拥有多达6条线性的有角传动的轴线并且有能力快速的从一种加工方式向另一种加工方式转变来满足不同种类的加工刀具和有效的减小地板空间。

c．装载工作和卸载工作，转换刀具，矫正，故障寻找所需的时间正在减少，应此生产能力提高，减少实验的需求尤其是对于熟练实验的要求并且生产成本降到最低。

d．他们可以高速的自动化并相对地紧凑，应此一个工作人员可以在同一时间照顾到两台或更多的机器。e．加工机器装备了刀具调节监测装置为了检测出工具的磨损与破裂，又可以探测工具磨损的补偿和工具调位。f．前处理和后处理的矫正和工件加工监测在加工中心的功能。

（20）加工中心可应用于更广阔范围的不同种类型号和特征，并且他们的成本范围从5万到100万甚至更高。典型容量范围可达75KW，并且最小轴转速通常在4000-8000rpm范围里，一些可以达到75000rpm，还用于小补偿切削的特殊应用。一些托盘具有支撑重达7000kg工件的能力，通常高的容量用于特殊的应用当中。

（21）现在大部分机器有一个标准组件的基准构造，应此不同种类的外围装备和附件可以被安装并且和修改不同种类产品的修改要求。

（22）因为加工中心的高生产能力，大量的切削会产生并且必须被收集起来应此一些需要一些可用于切削收集处理的设计，就像图示所举例那样，两个在横轴加工中心截面图底部的切削传送带这些特殊的加工传送带是螺旋形或螺杆型，他们沿着导槽收集切削并且将他们输送到收集点，另一条系统会选用链式传送带。刀具的选择

（23）加工中心能够有能力需求有效的花费可以说进行有效的成本控制，他们通常不得不每天做至少两次移动，所以他们必须有效并且可以连续调整在加工中心中产品的购买需求，因为他们固定的多功能性，但是加工中心可用于及时的制造大范围的特殊产品。（24）种类的选择和加工中心的尺寸依赖于以下几种因素。

a．产品的种类，尺寸和模具的复杂性。

b．加工方法的种类及执行方式和切削工具的需求次数。c．精确补偿的需求。d．生产速率的需求。

（25）尽管多功能性是选取加工中心的一个关键因素，我们必须考虑到权衡高成本高精度需求和比较在运用传统加工工具制造相同产品时的成本。

UINIT 4铸造工艺

引言

1锻造是一种重要的成型加工工艺。可以用来生产各种形状和尺寸的零部件，这些零部件从非常小的到重达几吨的。2锻造是把金属加热并且在合适的压力下使其塑性变形而成型的一种加工。通常这个压力是通过电锤或压力机的锤头打击面形成，如图4.1所示。

3手工锻造工具包括各种形状的锤子。在铸造过程中用来支撑工件的支座是砧座。

4对于半机械化铸造的小型和中型的零件，铸造锤所使用的各种动力都用共同的特点，例如手工铸造锤，他们利用它下落时的重力来提供金属成型时所需要的压力。大型零件的铸造是通过蒸汽或被压缩空气或液压或电力来提供铸造压力的。大型自动化锻造设备是用来生产大批量的工程部件。

5开模锻比如通常使用锤锻及闭模之间的差别。在锤锻中，组件是通过锤子的撞击和辅助的简单工具成型的。他们包括开式模具，即不会完全把金属封闭起来的成型。锤锻一种最基本的操作拔长是通过锤子的撞击金属拉伸片状金属，从而使金属变得又薄又长。在手工锻造中，工件在撞击下要旋转90°，从而可以完全锻造并阻止其侧面的进一步变形。与拔长相反的是镦锻，它能使压缩方向缩短。例如，将棒料加热并进行轴向捶打，其直径即可增大。

6闭模锻造广泛应用于大量的工业生产中，金属的成型是被压入一对锻造模中而完成的。上模通常与锻造压力机的撞击工具或锻锤相连接，下模是固定的。把他们结合在一起就形成了闭模。闭模锻造可以生产非常复杂和精度很高的组建，他们与传统的加工方法相比可得到更好的加工表面。磨具通常是由耐热和耐磨材料制作而成的。将一块大小足以填充模腔并能稍溢出的金属放入底模，并将顶模加压合拢。这块金属便获得该模腔的形状。闭模锻造通常用来加工连续加工的小工件或非常大的工件。对于后者的加工，例如喷气式飞机的组件，要使用很大的能产生5000吨或更多压力的水压机来提供压力。

7一种特殊贵重的锻造可以通过完善结构，均匀工件来改善金属的强度；因此对于重型锻造，；例如螺旋桨，有时要用10000吨的水压来挤压金属件。尽管水压锻机的比落锤锻造设备要贵的多，但它们可以给大型部件提供更大的压力和更均匀的组织。对于高压和挤压操作还要注意，它的操作场合比落锤锻造要低噪音少震动。对于重达30吨或更多的铸块须用机械锻造来完成加工，手工加工是无法完成的。

8锻造细化晶粒结构，提高金属的物理性能。合适的设计可以使晶粒流动方向与实际使用时的主应力方向一致。如图4.2所示，在塑性变形时晶粒沿木模方向流动。物理性能如强度韧性在锻造中要比未锻造要好的多。在未锻造时，晶粒是任意方向的。

9锻件每一部分都是一致的，没有孔，空缺，夹杂物质及其他缺点。因此，最终加工如机器加工不存在孔，因为里面不存在空隙。操作的薄层如盘状或直的，使工件有光滑表面。

10已锻部件小重量就有一个很高的强度，因此用于飞机支架设计。

11锻造金属可导致下面几方面：1）长度增加，横截面减小，称为拔长。2)长度减小。。12上述锻造使晶粒流动，形成高强度零件。13金属可以热锻也可以冷锻。14

第二篇：机械工程英语翻译机械工程英语第二部分翻译[范文模版]

Unit 1 1中央控制单元（CPU）的功能是控制所有系统部件的运行和对数据进行数字的或是逻辑的操作。为了完成上述功能，CPU由以下两个单元组成

2．控制单元．数字逻辑单元

3控制单元通过程序指令来协调大量的特种操作，这些操作包括接受输入计算机的数据，并决定和是以何种方法来处理这些数据。控制单元能指挥数字逻辑单元的操作，他把数据发送给ALU来告诉ALU根据这些数据该运行什么功能，并且在哪里把结果存储下来。控制单元完成上述操作的能力基于其安装了一个具有储存与记忆功能的总控程序机构。

4数字逻辑单元运行诸如加减比较之类的操作。这些操作是根据数据以二进制的形式表现出来的。在指示了确定的条件下，逻辑部也可以用来改变命令执行的次序。此外，逻辑部分还具有编辑或清除数据等功能。

5控制单元和数字逻辑单元都是得用寄存器来完成他们的功能的，计算机寄存器是一个可以接收短暂存储，转移数据的小记忆装置。根据计算机能力的不同，寄存器能建立出相应的字节数的字长。每个词的字节数从4到64不等！

Unit 2 生产设备的数字控制（1）数控是程序控制的自动化，在数字控制系统中，设备通过数字，字母和符号来编码，以一种合适的格式为每一个特定的零件或工件定义一个程序指令集。当工件变化时，程序也变化，改变程序的能力也就是适合中小批量生产。写一个新程序比改变大量生产设备要容易的多。

（2）基本结构：数控系统由下面三部分组成：1.控制程序；2.机器控制单元；3.加工设备。

三部分的基本关系，由图2.1 所示。程序输入到控制单元由送入的程序来引导加工设备控制。

（3）指导程序是一步步详细的指导加工设备的指令。通常指令把主轴上刀具相对于安装工具的工作台定位。更多先进的说明包括主轴的转速，加工工具的选择及其功能。程序刻在合适的介质中，提交到机器控制单元中，在过去几十年中，最常用的介质是一英寸宽的打孔纸带。由于打孔纸带的广泛使用，NC 有时也叫纸带控制，然而这是现代数控使用的误称。现在进入使用更多的是磁带和软盘。

（4）机器控制单元（MUC）由电子和控制硬件组成，机器控制单元可以读出和执行指令程序，可以自动改变加工工具和其他加工设备。

（6）数控有2 种基本类型，点对点式和轮廓式控制，点对点式控制也称定位控制，每个轴都是通过丝杠单独驱动，根据加工类型不同，加工速度也不一样。机器开始以最大速度运行来减少非加工时间，但当他达到数据定义的位置时，机器开始减速。因此在一个操作中，如钻或冲孔操作先定位在加工。在钻或冲孔之后，迅速收起工具移动到另一个位置重复此操作。从一个位置移到另一个位置是非常重要的，要遵循一个原则，从效率上考虑只要时间最短即可。点对点系统主要用于钻，冲孔，直铣操作中。

（9）有一些已形成差补方案来处理数控系统中连续路径和加工系统产生的问题包括：

1.线性差补；2.圆弧差补；3.螺旋线差补；4.抛物线差补；5.立体差补

（13）螺旋线差补结合了环形差补两轴在第三轴上做线性运动这样来定义空间三维螺旋路径。

（15）数控技术运用于数控机床，这是数控的主要应用。现在主要用于商业。我们仍讨论数控系统特别是金属数控车床。数控车床技术

（16）种加工过程都可以在设计的专门车床上来实现加工。在车床上车削，在钻床上钻，在铣床上加工。有几种类型的磨削方法也要有相应种类的磨床。被设计的数控磨床可以进行下列加工包括：1.钻加工；2.铣床立式和卧式主轴；3.车床卧式主轴和立式主轴； 4.卧式和立式镗床；5.仿形铣床；6.平面磨和圆柱磨

（17）除了上述几种机械加工方法，数控机床可用于其他金属加工过程包括：用于薄片板的金属板上冲孔的冲压机，用于薄片金属弯曲的折弯机。

（18）数控技术的介入到机加工对机床的设计和运用有着显著的影响。数控影响之一在程序控制下切削金属的时间与传统手动机床__ 大得多。所以对于一些零件如主轴驱动主轴丝杠磨损更快，这些零件要设计成持续时间长的。第二，增加电子控制单元后设备成本也随之增加，因此需要更高的利用率。取代传统手工操作的一班制，数控机床通常采用两班或三班制来获得更多的回报。数控机床的设计中减少了非操作过程的时间如装卸工件和换刀时间。第三，增加的劳动成本由人工成本变为设备成本。考虑到人工操作的角色，角色由技术熟练的工人控制，工件生产的每一个过程变为只控制装卸换刀和清除碎屑和类似的操作，这样一个工人可以同时操作两台或三台车床，机床的角色和功能也改变了。数控需要设计成高度自动化具有需要在不同车床加工几种操作联合在一起一定加工的能力，这些变化是通过一种新型车床在数控技术存在之前是不存在的，他丰富了数控加工中心

（19）加工中心是在20 世纪50 年代发展起来的具有在程序控制下在一个工件上一次裝夹完成几种不同的加工能力的机床。加工中心能完成铣，钻，铰屑，攻丝，镗，车端面及一些类似机加工工作。另外数控加工中心的典型特征包括以下方面：

（20）(1)自动换刀能力: 多种机加工工作一位着需要多种刀具。刀具贝安装在刀库或多刀刀库中。当一把刀需要被调换时，多刀刀座自动旋转到相应的位置上。自动化的换刀机构。在程序控制下进行，把主轴上需换下的刀和多刀刀座上的刀调换。

（21）(2)工件的自动定位: 大多数加工中心都可以使工件沿着主轴旋转因此允许刀具达到工件的四个表面。

（22）(3)托架滑动装置（平板架）: 加工中心另一个特点是有两个或多个独立拖板每个拖板都可以调整在刀具上。在加工过程中，一个拖板在刀具的前部，另一个拖板在远离主轴的安全位置。这样当机床正在加工当前的零件时。操作人员就可以从上一个工作循环中卸下最终加工好的零件，同时加紧毛坯用于下一个工作循环。（23）加工中心可以分为立式和卧式。这是参照机床主轴方向来划分的。立式加工中心具有轴线相对工作台垂直的主轴，卧式车床的主轴轴线是水平方向的。这种区别通常会导致在这些加工中心加工的零件类型不同。立式加工中心用于以上进刀的平面工作。卧式加工中心用于立体形状，刀具在立体侧面可以进刀。一台数控卧式加工中心，例子如图2.2 所示，具有上面提到的一些特征。（24）加工中心的成功应用导致了其他类似金属加工机床的发展。例如：在车削中心，把车削加工设计成一个高度自动化万能机床可以完成车削，刨，钻，螺纹加工和类似的操作 DNC AND CNC（25）数控的发展在分批生产和小批量生产中有着重要意义，从技术和商业角度来说都有着重要意义。数控有两方面的提高和扩展，包括：1.直接数据控制；2.计算机数字控制（26）直接数据控制

直接数据控制定义为一个制造系统，一定数量的机床有一台计算机通过直接硬件连线实时控制。相应的磁带播放机忽略在直接数控中，这样就消除系统中最不可靠的环节。不用磁带播放机而用电脑信息传给车床。原则上说一台计算机可以控制100 台独立机器（DNC 系统在1970 年称为可控制26 台机床）直接数控（DNC）电脑设计成在需要的时候提供指令给每一台机床，当机床需要控制指令时，计算机立即发送指令给机床。

（27）图2.3 说明了DNC 的基本配置。这个系统包括4 部分： 1.中央计算机；2.大量内存，用于存放数控程序；3.通信线；4.机床刀具

（28）计算机从海量内存中取出部分程序指令送入到需要的独立机床中。相应的计算机也接受机床反馈信息。这种双工的信息流在实时控制加工系统中出现意味着每台机床需要指令的请求能立即得到回应。类似的，计算机必须总是要准备要接受信息和进行回应。DNC 系统显著特点是：可以实时控制大量机床。更具机器数量和所需的计算机程度化。有时需要使用卫星计算机如图2.4 所示。卫星计算机是更小的计算机，可以分担中央计算任务，减轻其负担。每台卫星控制几台机床。零件加工指令程序由计算机接受，储存在内存中。当需要时卫星计算机发送指令程序到每个独立机床中。来自机床的反馈数据在电脑中央存储接受之前存储在卫星内存中。（29）计算机数字控制

由于DNC 技术的介入，在计算机技术上得到了很大的发展。计算机在尺寸和成本显著减少的同时，计算机的能力却有很大的提高。在数控中，这些发展使得由硬件布置的MCU（）变为数字电脑控制的控制单元。最早，小型机在1970 年使用。随着计算机进一步小型化，小型机被当今的微型机取代。

（30）计算机控制也是一种数字控制，它采用微型计算机作为控制单元。由于数字电脑用于CNC 和DNC 中，只近似区分两种类型。有三个区分原则：

1）.DNC 电脑接受和发送指令数据都是来自许多机器，CNC 电脑控制只是一个机器或多个机器。

2）.DNC 电脑占有一个位置通过控制来实现机器的旋转。CNC 电脑要非常靠近车床。

3）.DNC 软件的发展不经可以控制生产设备的每个单独零件，还可以在生产坚固性方面提供主要控制信息。CNC 的提高可以提高特殊车床的能力。

（31）电脑数控系统的大体配置如图2.5 所示。如图中所示，最初进入控制器的是磁带播放机。这样，CNC 的外部系统与传统的NC机相似。然而CNC 中的程序使用方法是不同的。

Unit 3数控编程

数控编程由一系列方向构成，这些方向导致数控车床执行某种操作，加工是最常用的进程。数控车床编程由内部编程部门来完成，在车间里，或者从外部源购买。编程还可以手动或者在计算机辅助下来完成。程序包括指令和命令。几何指令涉及刀具和工件间的相对移动。进程指令涉及主轴速度，进给以及道具等。行动指令涉及插值的类型以及刀具或者工作台的缓慢和快速移动。切换命令涉及到开/关冷却液供给状况，主轴旋转，主轴方向，换刀，工件进给，夹具固定等等。（1）手工编程。手工编程包括根据部分工程图纸首先算出刀具，工件以及工作台的尺寸关系，继而决定执行的操作和工序。那么一个包括执行特定操作所需必要信息的程序表就准备好了，例如刀具切削，主轴转速，进给，切削深度，切削液，以及刀具或者工件间的相对位置或者移动。根据这些信息，部分程序就准备好了。通常一个纸带首先被准备好用于试用和调试程序。根据纸带被使用多久，纸袋通常用更耐用的聚酯薄膜制成。

手工编程可以由那些具有特定制造工艺知识和能够理解，阅读以及更改部分程序的人来完成。因为他们熟悉机床刀具和工艺流程，熟练的机械师可以做一些手工编程的编程培训。然而，所涉及的工作是乏味的，费时的，因此不合算。手工编程大多数用于简单的点对点应用上。（2）计算机辅助编程。计算机辅助编程是一种涉及到特殊符号的编程语言，这种语言可以决定角点的坐标，刀口以及工件的表面。编程语言是与计算机通信的方式并且涉及到符号字符。编程员用这种语言描述加工零件，而由计算机将零件程序转换为数控机床的执行指令。许多种商业应用上的语言有多种多样的特点和应用。第一种被使用的是类似于英语语句的语言，它在十九世纪五十年代末被开发出来并被称为APT语言。这种语言，由于它多种多样的扩展形式，一直是最广泛的用于点对点和连续路径编程的语言。

复杂的工件现在使用基本的绘图进行制造，计算机辅助制造程序。刀具的路径是在类似于一个CAD程序的大量的绘图环境下制造出来的。这种机器代码由程序自动生成。

在生产开始之前，程序应该被校验，还有就是通过一个显示器观看工艺流程的模仿或者使用廉价的材料（例如铝，木头，石蜡，或者是塑料）制作工件，而不是使用指定用于已加工零件的真实材料。

计算机辅助编程有以下几个优于人工方式的重要优点。

比较容易使用的符号语言

缩短了编程时间。编程是一种容纳了大量关于机械特点和工艺变量数据的一种能力，例如动力，速度，进给，刀具形状，刀具形状改变的补给量，刀具磨损，偏转，以及冷却液的使用。

减少了在人工编程中出现人为错误的可能性。

因为编程时所需更少的时间，降低了成本。编程语言的使用不仅导致更高的工件质量而且考虑到了机械指令的更加快速发展。另外，模拟可以在远程计算机的终端设备上运行，这就确保了程序按照既定来运行。这种方法可以防止昂贵的机器由于调试程序产生不必要的占用。

选择某一种数控机床编程语言主要取决于以下几个因素：

生产设施人员的专业水平级别

工件的复杂程度

设备的外形以及计算机的应用

涉及编程的时间及费用

因为数控涉及有关工件材料和加工参数的数据插入，编程必须由有制造业的相关方面知识的操作工和程序员来完成。在生产开始之前，程序应该被校验，还有通过一个CRT屏幕来观察工艺流程的模拟或者用廉价的材料制造工件，例如铝，木头或者塑料，而不是使用指定用于已加工零件的真实材料。数控编程语言

自从1956念麻省理工学院的初步研究数控编程系统以来大概有超过100种的数控编程语言已经被开发出来了。大多数语言开发用于特殊的需求和机械并且它们没有经受住时间的考验。然而，相当多的语言在今天一直被使用。在本小节，我们回顾一下那些被普遍认为是重要的语言。

APT(自动编程工具)，APT语言是麻省理工学院研发的关于数控机床控制编程系统的成果。它的研发开始于1956年六月，它第一次用于生产是在1959年左右。几天它是在美国应用最广泛的语言。虽然第一次打算作为一种轮廓语言。APT现在的版本可用于定位和持续路径的编程而且可用于多达五个基准轴的持续路径编程。

AUTOSPOT(用于定位工具的自动系统)。这个程序有IBM研发，在1962年第一次被引进用于PTP编程。AUTOSPOT现在的版本也可应被用于修证轮廓。

COMPACT II。这种语言是来自于制造数据系统的封装。（MDSI公司），在安阿伯，密歇根州的一家公司。数控机床控制编程的许多特点于SPLIT相似。MDSI公司将COMPACT II系统租赁给以分时为依据的用户。这种程序通过使用远程终端把程序传送给MDSI公司的计算机，有计算机转向产生数控的纸带。

ADAPT（APT的改编版本）。多种编程语言直接依据于APT程序。这些语言之一便是ADAPT，它是在空军合同下由IBM公司研发的。这种语言意图提供许多APT的特点但是用于小型计算机。ADAPT不如APT一样强大，但是能够被用于定位和修改轮廓工作的程序。

EXAPT(APT的扩展子集)。这种语言是由德国研发的。，开始于1964年之间，以APT语言为依据。有三个版本：EXAPT I ——被设计应用于定位（钻削和直切铣）。EXAPT II——被设计用于车削，还有EXAPT III—被设计用于限制轮廓的操作。EXAPT最重要的一个特点是尝试自动地计算最佳进给量和进给速度。

APT不仅仅是一种数控语言；它也是一种以APT声明为依据执行计算来。生成切割位置的计算机程序。在APT语言中声明有四种类型：

几何声明。这些定义好的几何元素包括了工作组。它们有时也叫做定义声明。

后处理程序声明。这些声明用于特殊的机械工具和控制系统。它们用于指定进给量和进给速度而且精确了机械的其他特点。

辅助声明。这些不同种类的声明常用作定义工件，刀具，以及公差等等。

铣床和车床的CNC编程于其他机械编程工艺是相似的；它需要对编程语言有一个透彻的理解。这种用作铣床和车床NC的语言通常被称为G代码。这些工序通常用于铣床机械和机加工中心，提供了一些G代码使用的经典例子，因为它包括大约了NC操作中的75%。下面编程和工艺的五类用于铣床NC编程。（下转P114）自动化编程的人工指南

NC机械编程采用两种形式：人工编程以及在CAM软件支持下的代码生成。例3-1是一个人工编程的例子。它以铣削零件图为开始，编程者设计一些能够驱动切削刀具沿着预期路径运行的G代码工序。CAM生成的NC代码为了使目标机械工具能够直接转换为零件图送给G代码程序运行在已选择的机械上，从而使用一个后处理程序。CAM软件和后处理程序分成两类。类型之一，专业CAM和简洁CAM，它是独立的，并且吸收了所有主要CAM供应商的绘图文件。第二种类型，是被CAD供应商研发的，它集成了CAD程序和运行，作为集成CAD / CAM设计软件的一部分

Unit 4 机加工与切削加工中心

（2）需要注意的是每台机器他的自动化程度有多高，都要设计一种基本的加工样式就像所展示的那样，在制造过程中不同的表面是用不同的加工方法加工的，（3）例如，如图4.3 所示，铣、端面车削、镗、钻、铰孔、切丝来获得额定的公差要求及最终表面精度。

（5）有这样一些产品或加工方法，他们的生产路线是不可行或不经济的，特别是当这些种类的产品在加工时需要迅速转换加工方法。一个重要的概念，在20 世纪50 年代末期得到发展，那就是机加工中心。一个机加工中心就是运用计算机控制的刀具在工件的不同表面和不同的方向上进行切削操作的能力，通常说工件是不动的，而切削工具进行旋转，比如铣和钻操作。

（7）工件在加工中心里是被安放在托盘上或模块上，那样可以被移动并且可以进行不同方向的旋转和定位，在进行特殊的切削过程完成后，工件不需要移动到另一台机器进行钻孔，铰孔，攻丝之类的附加加工。换句话说，工件和机器是被置于工件上的。（8）当所有的加工工作完成后，托盘会自动离开已加工工件，并且另一个托盘运用自动托盘变速器将工件进行定位和加工。所有的传动机构都有计算机控制，并且托盘定位器有10-30 秒的循环时间，托盘台能够使得多级托盘更好的服务于加工中心，工具同样能够被装备到不同的自动化部件中，诸如上料与下料机构。（9）加工中心装备了可变程序的自动刀具变换器，依赖于这样的设计多达200 把切削刀具能够被贮存在刀库，刀鼓，刀链（工具库），辅助工具库能够更好的为一些特殊加工中心提供更好的切削道具，这些刀具可以自动的任意选择到达机械主轴的最短路线，刀具交换臂是一个普通的设计机构，他可以旋转来拾取特殊的工具（每一个工具有他自己的刀杆）和他在主轴上的位置。

（10）刀具通过直接连接在刀具夹持口上的编码标签、条形码或记忆芯片来标识。一次换刀时间在5-10 秒钟，对于小的刀具可以少于1-2 秒，对于重达110 公斤的刀具可以达到30 秒，刀具变换器的设计趋势趋向于运用简单的原理提高换刀的时间。

（12）图4.6 所示的一些表面可以被联系起来，他们的相对位置可以被确立并储存在计算机软件的数据库中，这些数据稍后可被用于编写刀具工作路径的程序同时对刀具的长度和直径进行补偿，又可以为预先加工刀具的磨损提供补偿。机加工与切削加工中心的种类

（14）垂直主轴加工中心或是水平主轴加工中心都是为了适用在工件具有深腔的平面上执行加工工艺，如铸型和模具制造。一个垂直主轴的加工中心类似于一个垂直主轴铣床。刀库在图示的左侧并且所有的加工方法和传动机构通过位于右侧的计算机控制托盘进行定位和修改。（15）因为在加工中心中由于推力的作用方向是向下的，机器具有高的刚度，并在对于加工部分有较好的精确补偿，这些机器通常比水平主轴的机器便宜些。

（16）水平主轴的加工中心或水平机加工中心是为了适用于高大工件的表面加工的需求。托盘可以在不同的轴线（如图4.3 所示）上旋转来进行不同种类的有角定位。

（17）水平主轴加工的另一个范畴是车削加工，是用特殊机床进行计算机控制的车削加工。一个三转动架的计算机数字控制的车削加工如图4.8 所示，这个机器是由两个水平主轴和三个转动架以及不同的切削刀具设计而成的来执行一些旋转工件的加工。

（18）万能加工中心同时装备了垂直主轴和水平主轴的机器，他们具有不同种类的特色，并且具有加工所有表面的能力（垂直的、水平的、斜的）。

机加工中心的特征和能力

（19）下面是加工中心的大部分特征：

a．他们有能力有效的，经济的并且拥有重复的高精度的尺寸的能力来处理不同型号的磨具的能力。公差的范围在正负0.0025mm。b．这些机器是万能的，拥有多达6 条线性的有角传动的轴线并且有能力快速的从一种加工方式向另一种加工方式转变来满足不同种类的加工刀具和有效的减小地板空间。

d．他们可以高速的自动化并相对地紧凑，应此一个工作人员可以在同一时间照顾到两台或更多的机器。

e．加工机器装备了刀具调节监测装置为了检测出工具的磨损与破裂，又可以探测工具磨损的补偿和工具调位。

f．前处理和后处理的矫正和工件加工监测在加工中心的功能。（20）加工中心可应用于更广阔范围的不同种类型号和特征，并且他们的成本范围从5 万到100 万甚至更高。典型容量范围可达 75KW，并且最小轴转速通常在4000-8000rpm 范围里，一些可以达到75000rpm，还用于小补偿切削的特殊应用。一些托盘具有支撑重达7000kg 工件的能力，通常高的容量用于特殊的应用当中。（21）现在大部分机器有一个标准组件的基准构造，应此不同种类的外围装备和附件可以被安装并且和修改不同种类产品的修改要求。

（23）加工中心能够有能力需求有效的花费可以说进行有效的成本控制，他们通常不得不每天做至少两次移动，所以他们必须有效并且可以连续调整在加工中心中产品的购买需求，因为他们固定的多功能性，但是加工中心可用于及时的制造大范围的特殊产品。（24）种类的选择和加工中心的尺寸依赖于以下几种因素。a．产品的种类，尺寸和模具的复杂性。

b．加工方法的种类及执行方式和切削工具的需求次数。c．精确补偿的需求。d．生产速率的需求。

（25）尽管多功能性是选取加工中心的一个关键因素，我们必须考虑到权衡高成本高精度需求和比较在运用传统加工工具制造相同产品时的成本。

Unit5 工业机器人

介绍

工业机器人是相对来说较新的机电设备，它已经开始改变现代工业的面貌。工业机器人不像科幻小说中的那个模样具有人一样的能力并且能与其它移动物建立友谊。机器人能够看见听到触觉听的研究已经进行了20多年，现在开始开花结果了。然而，通常所说的工业机器人技术是是大多数机器人只包含了一条臂而不是拥有人解剖学上的全部结构。通常的控制只允许这些机器人在空间上从点到点的移动，完成相对简单的工作。美国机器人学会定义机器人为“一个可再编程序，多功能的机器手，它通过各种可编程的运行来完成不同的任务，用于搬用原料、零件、刀具、以及专用装置。如果认为不同类型的加工有不同的作用。那么一个数控加工中心也可以被认为是机器人。大部分制造工程师认为数控加工中心不是机器人，尽管他们有很多相似之处。数控机构和机器人的动力驱动和控制十分相似。想数控机构一样机器人能够由发动机、液压系统、气压系统提供动力。两种设备都能由开环控制或闭环控制。实际上，许多应用于机器人发展技术由数控工业演变过来并且许多机器人制造商也制造数控机床和数控控制器。实际的机器人由带有腕（或称为臂）的主机身和机器端部的工具（通常是某些的支撑器）组成。机器人也可能有一个辅助动力系统。机器人系统还包括一个有一些控制环模、操作杆、键的控制器。一种典型的机器人系统如图5、1 机器人特点通常由机械系统的设计表现，一个主要框架包括三条移动轴的机器人称为笛卡尔机器人。笛卡尔机器人它的名字来源于笛卡尔坐标系沿三维空间的直线移动。一些笛卡尔机器人由龙门结构构成以便使沿每个轴的偏差最小。这些机器人称为龙门机器人。图5.2展示了笛卡尔机器人，这些机器人的动作控制都相似于传统的三坐标机床。龙门结构一般来说是最正确的机器人实际结构。龙门机器人通常用于公差较小和位置度要求较高的装配中。

圆柱机器人由两个移动轴和一个旋转轴组成，这种机器人的名称来源自包围轨迹（它的功作范围），它由轴移动的极限位置构成。图5.3展示了典型的圆柱机器人。圆柱机器人有许多应用，最常见的是材料的搬运操作。给机器人编程。

为了是设备具有资格作为机器人，它必须是容易可再编程的。不可编程的机构，无论其通过重新装配或再接线可实现的潜在柔性有多大，也不能算坐机器人。许多这类设备是固定的或可变的序列机器人。很多这样的机器人是由气压驱动的。这种机器人借助某种梯形逻辑图被驱动至一些固定的挡块活行程开关处，而不是控制它的轨迹。虽然梯形图编程可满足机器人的运动要求，但行程开关和挡块必须正常的被整体移动，以改变所需执行的工作任务。动力开动或发动机打开到“开”或“关”依据工序的要求和转换状态。机器人对这类系统操作通常局限于相当简单应用。

传统机器人的程序通常采用以下三个形式之一：（1）操作器编程（2）导入式程序（3）脱机程序。每个机器人通常具有一个或更多这种程序类型的系统。每种形式的优缺点依不同的应用而不同。

操作器编程最常用的机器人编程方式，这种类型编程，A pendant 通常包括几个用于使机器人在它工作范围移动的操作杆。在每个工序的终点，机器人的位置被保存。像数控机床一样，一些机器人允许编程人员选择定义两点间路线。另外，这些机器人被称为连续路径系统。不允许用户指定路径系统称为点到点系统。许多连续路径机器人允许用户定义在两个主要点之间连线的路径。那么，用户可以定义直线、圆弧的、指定某一位置的路径。在直线路径中，机器人在笛卡尔空间中，以直线两两端点移动。顾名思义，圆弧运动就是在某一主平面上沿圆弧运动。机器人以插入某处方案执行路线很不容易确定。在接点插补中，机器人的每一关节都以一恒定速度移动以保证所有的轴同时启动和停止。对于笛卡尔机器人，直线和结点插补方案产生相同的路径。对于其他类型机器人系统，这不成立。

操作器编程系统通常提供允许编程人完成辅助操作的命令，如关闭终端，等待，暂停，检查一种或几种转换状态，返回全部状况给机床，等等。编程人员使机器人走过要求完成一项工作的必要步骤，保存每一中间步骤和辅助的信息。用于给fanuc M1机器人编程的操作器，如图5.4所示。

导入式程序是最简单的机器人程序设计过程之一。顾名思义，编程人简单实际的是机器人沿着路线轮廓移动。机器人控制器反馈它的位置并且像编程人一样引导机器人完成操作。当编程人员负责引导机器人完成必要动作时，动力降低以便机器人不产生伤害操作人员。尽管导入式编程是最容易学的程序语言，但它也反映了一些机器人应用的限制，例如，当机器人正在进行操作时，操作人员搬运机器人。齿轮，电动机和丝杠会引入错误的运算读数值，这样当机器人的重量，也许是工件的重量必须由系统承担时，端部执行器的实际位置可能与机器人的训练位置有很大差异。这种方式的另一个问题是由于在机器人的位置和速度被记录指引通过期望的路径是，大量的数据信号产生，这些数据不需存储后调用，存储和从新调用的空间和时间可能会引起汇编器问题，也许与导入方程式协调的主要问题是引导机器人完成工艺过程的人能够做有限的准确可能引起工艺过程的不协调，人为错误和不准确性削弱了使用机器人的优点。

脱机程序对机器人来说是相对较新的技术，它能够提供导入式和控制板编程的一些优点。脱机程序的规律与对数控技术应用脱机语言类似。几种脱机语言已经在美国的主要大学和工业种发展。这些语言主要有unimation的VAL,美国机器人协会的ar-basic,microbot,lnc的arm-basic和ibm的ami，以ar-basic为例解释说明脱机语言，ar-bisic允许用户定义机器人的位置控制机器人的运动输入输出控制数据

ar-basis系统的细化，他采用的许多相同的功能采用了我们熟悉的basic程序语言，在ar-basic中，点和刀具定义为初始化数据点由以下协议定义 x,y,z,r,y X，y,z表示由端部执行器占据笛卡尔空间，r p y表示刀具旋转进给和yaw.每个点的定义既可以是绝对的夜可以是相对的（也和数控机床有相似的规则）

刀具定义命令常用于定义操作要求的所有刀具的位置，刀具定义指定机器人面板的中心，包括等定义点相同的六个数据

机器人通过运动控制命令执行运动，运动命令允许编程人定义采取的路径类型（直线，圆弧，结点插补）定义刀具的最终速度定义参考柜架定义刀尖的类别

AR-Basic也允许程序编译人员输入，输出数据到与机器人连接的设备，模拟的数字信号可以传送到模—数转换转换器并行的或串行的I/O口。表5—1是点和刀具定义的举例。表5—2举例说明了AR-Basic的运动控制。

Unit6 成组技术

成组技术是一个制造业的哲学概念，它涉及到具有相似或相关属性零件的标识和分组，这样我们可利用产品的相似性这种特点把这种技术应用于产品的生产的设计制造生产过程中。历史上，这项新奇的技术首先出现在1920年的美国，当时Frederick Taylor也认同成组部件需要特殊工艺的观点紧随其后的是琼斯和拉姆森机械公司在20世纪20年代初，这个公司使用的是一种简陋的成组加工方式来生产机床，他们使用这一原理的方法就是以产品来划分部门而不是以工艺或缩短路径来划分部门。现如今，成组技术通过良好的结构分类和编码系统和应用支持软件采取的相似组成部分取得优势。

现代制造技术正投许多日益增长的国际化竞争与快速变更的市场需求所引起的挑战进行着比拼。下列的这些挑战已在成组技术中遇到过。

第一段略。

作为第一个因素的结果，传统的销售组织变得非常低效和浪费，这都是因为产品在不同的加工部门之间奢侈的路径（直接翻译的不很对）。为了缩短准备时间有必要使设计与生产环节紧凑起来，从而获得在国际市场中相对有利的位置。

1.产品设计中的益处。涉及到产品的设计，组成技术的原理益处就是它能够是产品设计者避免”重新设计车轮”(即重复改造)，或者加大设计的影响，换句话说，它排除设计一个已经被设计过的产品的可能性，因为他使储存变得容易并且使工程设计的检索相对容易些。（下句书中有）如果精确部件的设计不包括在公司的电脑档案中，一个设计将足够接近那种被需要的能够被检索并且调整调整到为了满足需求的程度。成组技术的进一步优势是它促进了设计特征的标准化，诸如角半径，倒角这一类的，从而导致了生产工具和生产设备的标准化。

2.模具和安装的标准化。自从部件被分门别类处理后，一个柔性的生产设备的设计能够使得其适应用同一种方式加工的同种类别内的各种加工，从而通过减少夹具来减少其所需的费用。同样的，一个机器的安装也可以适应整个类别而不是独立部件。3.已有

4．提高问题式生产的经济体系。通常，间歇式生产涉及了许多非标准部件。似乎毫无共同之处。因此，不同类别的分组部件使得经济效益的获得只存在于大批量生产中。

5．更容易调度。将部件分组方便了任务的调度，使得工作时是完成一类的加工而不是只加工单个部件。6．减少工作进程和准备时间。7 更快更合理的工艺设计。成组技术为自动化流程规划铺平了道路，这可以通过适当的零件分类和编码系统来实现，在每个部分的详细过程图中储存代码，从而方便检索。

Unit7 1 CAD/CAM(计算机辅助设计)是一个以电脑为辅助设计或用电脑辅助设计的一个术语。它是一种在设计和生产过程中运用数字电脑来完成特定功能的一种技术。这一技术正朝着设计和制造，这两个曾被传统的认为在生产过程中有名自独立分工职能的两个过程相结合的过程发展。总之，CAD/CAM将会为今后的计算机结合产业提供技术基础。

2、由硬件和软件组成的电脑系统将执行由特定用户所提出的特殊的设计功能基础的CAP硬件包括：电脑。一个或多个终端器图像显示、键盘、及其他的一些外部设备。CAD的软件包括能在其系统内运行计算机图表的计算机程序及能为公司用户的设计工作提供便利的应用程序。例如：分力压力分析（程序）机器的动力回应（程序）热交换计算程序、及各种控制程序等。由于生产线、制造工序及顾客市场的不同，各种应用程序也会随不同用户的需求的转变，因而这些工厂也带来了对CAD系统需要的差异

3计算机辅助制造（CAM）可以被定义为通过拥有车间生产信息的直接或间接的电脑界面利用计算机系统来计划、管理和控制制造工厂的运作。其定义表明，计算机辅助制造的应用可分为两大类：一计算机监控和管理，这是计算机为了监控和管理生产过程最直接的应用且于生产过程直接相联系

二、以制造为支撑的应用、这是计算机被直接用于工厂的生产运作，但其中并没有计算机与制造过程直接联系的界面

CAD/CAM系统具有一套全新的制图基本原理，其中的任何一个都能提高制图效率。例如：目前市场上大多系统都是具有能将新兴的实用的制图技术制动化固有功能。如分层技术使得制图能按逻辑结构制图，立刻组成一个整体，并被分开保存以便识别，但这些部件并演示整个制作过程。这一过程与我们在生物中所见到的解剖图样类似。骨骼，神经，内脏，血管和肌肉分别由具有不同颜色的塑料所替代。他们被看做个体，或者把他们叠加在一起，来显示各个部件之间是如何相匹配的。通过图象系统来分层设色，采用相同的原则，除非覆盖物是逻辑的而不是非物理的。诸如此类的应用有很多。分层也可用于区分英文和数字维度信息，数据信息。文本信息，电子需要锯锤测探、机械部件路径等。结果是清晰、明了的图样其它分析的好处：

CAD/CAM也可以通过其它方式影响一个公司的工程系统，它能把所有的物理过程流线化，并且允许对现代化的工程技术方法和工艺过程进行重新评估。CAD/CAM提高了确保质量的技术，自然而然的适合于保持精度完善文件材料，并且保存了零件的数量与材料清单的精确记录。一个完全集成CAD/CAM系统的正确安装，促进了一个公司对设计及生产方法的评估，并且开创了那些方法所适合的标准。通常这个评估证明是有效的，但也能给那些没做好准备的人带来意外伤害。对这两方面的问题都考虑到的管理者是很聪明的，CAD/CAM的应用始终都是一件复杂的事。缺点是什么呢？

CAD/CAM的缺点或许并不明显，但即使对于最好的设计也是‘具有破坏性的。其中最大的缺点是来自于从手工草图和保存的记录到CAD/CAM系统径直移动所必须的跳跃。这就好像是把喷气式飞机的引擎安装在大众汽车上，汽车开始可能在很短的时间内行驶的很快，但是，如果底盘不够坚固来处理作用力，那么所有的设计将震动分离。换句话说，CAD/CAM将突出工作最脆弱的区域的不完全性，这对于人和不能保持的规则来说是残忍的，就像一个对它的描述：“如果一个公司内部对绘图材料清单和部分数字系统不能很好的使用，CAD/CAM系统将使问题恶化。”

当这种令人不满的结果发生时，通常会把矛头指向CAD/CAM系统---虽几乎是不能谴责的是，但通常比将矛头指向人或组织更好。任何一台计算机将只能在输入数据时工作，这是最基本的数据处理规则：废物进，废物出。如果一个公司正在使用一个不完全的目录控制系统，仅仅是因为它是自动的。这个系统将得不到改善。事实上，自动化将会使这个不完全更加明显。并且可能更混乱。因此当实施CAD/CAM系统是不仅评估技术的需要很重要，而且对于期望提高的现存的规则也是很重要的。

如果管理者不愿对现存的操作条件，标准，工艺过程进行评估，那对CAD/CAM的使用将很可能会失败----因为一系列的原因。原因之一，管理政策将因为CAD/CAM系统与标准操作过程的分离而不能被很好的组织。在低水平的管理者中将产生一种这个系统永远不会被人们有效使用的感觉。另一个原因，不同的部门之间的信息通道还没有建立起来，这也导致产生CAD/CAM系统不能被长期使用的感觉。还有一个原因，就是操作员对系统实施的方面没有输入，这就导致了绘图标准的缺点，系统管理的贫乏，系统使用者的无知，这种循环是不可原谅的。特别是对于标准操作条件的评价将直接给提高这些工艺过程提供意见，即使是CAD/CAM系统从来没被使用过。CAD/CAM的应用

CAD/CAM技术从画图板发展到如今已经经过了一个很长的历程，它已经广泛的应用在各种工业生产，涉及范围从航天飞机控制到武器研究。从绘图到动态诊断，从电路分析到结构钢分析。CAD/CAM广泛应用于绘图和制造的各个环节，从绘制影视音像设备草图到控制大量的机器人组装线，它的用途在不断的发展。

CAD/CAM首先应用于电子制作业。这是因为CAD/CAM并不是一项公认的超越计算机产业的技术。人们才觉察到CAD/CAM在航空民用工业等领域的市场需求。新的复杂的设计已经无法由借助查图手册的手工绘图所满足。CAD/CAM成了必然的解决方法。如今这项技术已经具备了强大的技术和资金基础。因此，潜在的CAD/CAM的用户能够满足最终所采用的挑剔要求，他们再也不用购买低劣的或不会使用的设备了。当今的CAD/CAM市场：

现在，市场上有4种CAD/CAM的提供商。第一种是大型公司的附属机构或部门。IBM的CAD/CAM分部就是一个例子。这些分公司和他的总公司哟着大宗的商业买卖，他们不仅销售钥匙系统，还称作售后服务处。因为这些公司有着强大的后盾，所以他们的运作良好。但是他们同样受束缚作风的影响，使得他们的不能对市场变化作出快速反应，也不能把先进的技术用于生产线来提高设备的性能。

第二种是专门的交钥匙系统销售商。这些公司提供各种各样的作用于不同工业环境的CAD/CAM系统。这些公司已经从事CAD/CAM行业几年或几十年。他们已经在不断的技术发展中建立了良好的声誉，这类公司有。。，这些企业由于规格较小，有时不能提供很好的售后服务，但他们对市场反灵敏，能很好的满足客户的要求，能够提供各种可以使用的CAD/CAM系统。

第一种是新兴的CAD/CAM销售企业。这些公司比较小，年轻，富有创新精神，但他们的市场占有率仅为5%,但是每个公司都擅长为部分市场单人独特的高品质的系统。通常，这些企业销售的微型监控系统对需要小型化专业化的CAD/CAM系统的客户非常有用。事实上，这些客户在购买设备前都是经过深思熟虑的。

第二种是服务机构，这些企业专门从事CAD/CAM服务。来满足很小的或协调性的需求。服务机构越来越普遍并成为那些不能承担购买CAD/CAM系统费用或不具备购买条件的公司的首选。这些机构不仅参与CAD/CAM的相关商业行为，他们还能为那些将要考虑购买他们设备的企业进行相关培训和研讨。

和任意一种销售商做生意都有利有弊，大公司不容易讨价还价，而且他们技术革新缓慢，但他们大多能提供良好的服务和可靠的产品，专门的销售企业对客户的需求都加灵活，并且产品升级周期较短。

1、CAD/CAM是指一个以计算机为辅助设计或辅助制造的术语。它是一种在设计和生产过程中运用数字计算机来完成特定功能的一项技术，这一技术正朝着与设计和制造两个一直被认为在生产过程中各自独立、分工明确的两个过程相结合的过程发展。总之，CAD/CAM将会为今后的计算机融合产业提供技术基础。

2、这一计算机系统由硬件和软件两部分组成，执行由特定用户所提供的特殊的设计功能。基本的CAD硬件包括计算机、一个或多个终端图样显示器、键盘及其他的一些外部设备。CAD的软件包括能在计算机系统内部运行的图标和程序。例如，分力压力分析程序动力回应程序，热交换计算程序及各种控制程序等。由于生产线、制造工序及顾客市场的不同，应用程序会随用户的不同需求而转变。这也导致了CAD系统需求的差异。

3、计算机辅助制造CAM可被定义为通过拥有车间生产信息的直接或间接的计算机界面，利用计算机系统来规划、管理和控制制造车间的运作。其定义表明，计算机辅助制造的应用分为两大类： <1> 计算机监控和管理，这是计算机为了监控和管理提高制图效率1、2、3、它的潜能确实是无限的，生产率的提高只受管理原则性的限制。比如，可以把制图中心看做是一个专门设计货仓的建筑方。他们的多数工作都是重复的，可以在一项项工作中被反复使用。

例如，一个标准的地板或楼梯；亦或是一个标准的门或门框，系统可以再几秒内完成这项工作，同时制图者可以不必每次都重新设计必须插入到图中的部分。

4、此外还有许多使用的宏程序。一组放在一起的按钮可以自动的将图样的规格用英文自动转化为数字单元，或自动调节整个绘图，并使之旋转到理想的方位，或生成一张关于复杂工程绘图的材料清单。

5、更进一步的讲，整个设计过程都能被储存到系统中。当制图者接到一个与所储存的绘图规格相似的工作时，他只需重新调用它，把它引入工作存储库，再重新修改新工作中与原图的不匹配的部分的规格。这样效率就被提高了，原始工序被提高了效率，而反过来，下一步的工序也被提高了效率，这说明需保持和对用户易于操作的有完善与分进的数据库。

Unit8 柔性制造系统

关于柔性制造系统，有很多不同的定义，多数情况下，如何对其定义依赖于其使用者对其组成部分和使用方法的个人看法。

然而，接下来的描述是对FMS定义的概括，那就是有源可寻和无源可寻的资源。

美国政府：一系列的自动机床和生产加工设备项目与自动物料处理系统联系在一起普通级别的数据事先编程计算机控制，为任意生产加工的零件或组合列入预先给定的零件组中做准备。

Kvearney和Tvrecker：FMS是数控机床的组成。它能任意地执行零件组，自动化物料的处理和中央计算机控制动态平衡资源的利用。因此，系统能自动的适应在零件生产，产品的品种组成和输出方面的变化。FMS是一种可随意的指定任务的自动化系统，这种系统基于承租制造技术，结合了计算机集成控制和一组可连续进行零件的自动处理和加工的机床。

FMS结合了微电子技术和机械工程能够使批量生产更具有经济性，中央在线计算机控制的机床，其他工作站，能完成零部件的传输和加工。计算机也能提高监控和信息控制，这种结合了灵活性和全局控制的方式使小批量大范围的产品的生产成为可能。

在已有的能力和预先定义的规划范围内，在控制中执行零部件和产品的多样化生产。

一种将帮助精良工厂获得较快的加工时间的技术，是在一个较高水平的管理和中心控制下，实现较低的单元成本，较高的质量的生产。

基本上FMS是有软件和硬件组成的。硬件部分是可见的，可触摸的。例如：计算机数控化机床，旋转式托盘，物料传输设备（机器人和自动引导小车），集中是排屑系统，刀库，坐标测量机，工件清洗站和计算机硬件设备。软件部分是不可见的无形的，例如：数控程序，交通管理软件，刀具信息，坐标测量仪的工作顺序文件和复杂的FMS软件。图8.1是典型的FMS布局和它的主要动态性组成和可确认的组成部件。

Unit9

为了理解提高自动化综合生产力的限制因素，进行下面的类比，假设一辆汽车的多种辅助系统都已经自动化了，司机的工作会变得更加轻松，自动加速、减速、转向、刹车

将会比人工操作更有效。然而，考虑一下将会发生的事，如果这些自动化的辅助系统在一定程度上没有联系在一起，即不能即时的连续的交流与分享精确的最新的信息，一个系统试图加速，而另一个系统试图刹车。在自动化制造设备上有同样的制约，这些制约导致了如今制造技术发展的另一个阶段：集成。

Unit15 滑尺的平移运动是通过使用空气轴实现的，为了尽量减少摩擦，也为了减少因滑道缺陷引起的后果，一个合适的空气源是必需的。基轴的运动完全依靠于廉价的手动三坐标测量仪，大多数手动机器都配有一个精确地手轮装置，尽管许多用户更喜欢直接用手来移动滑尺。

更昂贵的机器采用马达驱动的轴驱动装置，采用直流伺服电机通过特殊的机制运作，各轴均有即断开关来控制并允许手动控制运动。

第三篇：机械工程英语第二版翻译

第一单元

• Types of Materials

材料的类型

Materials may be grouped in several ways.Scientists often classify materials by their state: solid, liquid, or gas.They also separate them into organic(once living)and inorganic(never living)materials.材料可以按多种方法分类。科学家常根据状态将材料分为：固体、液体或气体。他们也把材料分为有机材料(曾经有生命的)和无机材料(从未有生命的)。

For industrial purposes, materials are divided into engineering materials or nonengineering materials.Engineering materials are those used in manufacture and become parts of products.就工业效用而言，材料被分为工程材料和非工程材料。那些用于加工制造并成为产品组成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.工程材料还能进一步细分为：①金属材料②陶瓷材料③复合材料 ④聚合材料，等等。

• Metals and Metal Alloys 金属和金属合金

Metals are elements that generally have good electrical and thermal conductivity.Many metals have high strength, high stiffness, and have good ductility.金属就是通常具有良好导电性和导热性的元素。许多金属具有高强度、高硬度以及良好的延展性。Some metals, such as iron, cobalt and nickel, are magnetic.At low temperatures, some metals and intermetallic compounds become superconductors.某些金属能被磁化，例如铁、钴和镍。在极低的温度下，某些金属和金属化合物能转变成超导体。

What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金与纯金属的区别是什么？纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。

Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有：不锈钢是一

种铁、镍、铬的合金，以及金饰品通常含有金镍合金。

Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.为什么要使用金属和合金？许多金属和合金具有高密度，因此被用在需要较高质量体积比的场合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金属合金，例如铝基合金，其密度低，可用于航空航天以节约燃料。许多合金还具有高断裂韧性，这意味着它们能经得起冲击并且是耐用的。

What are some important properties of metals? Density is defined as a material’s mass divided by its volume.Most metals have relatively high densities, especially compared to polymers.金属有哪些重要特性？

密度定义为材料的质量与其体积之比。大多数金属密度相对较高，尤其是和聚合物相比较而言。Materials with high densities often contain atoms with high atomic numbers, such as gold or lead.However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由较大原子序数原子构成，例如金和铅。然而，诸如铝和镁之类的一些金属则具有低密度，并被用于既需要金属特性又要求重量轻的场合。

Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced.Metals can generally contain nicks and dents without weakening very much, and are impact resistant.A football player counts on this when he trusts that his facemask won’t shatter.断裂韧性可以描述为材料防止断裂特别是出现缺陷时不断裂的能力。金属一般能在有缺口和凹痕的情况下不显著削弱，并且能抵抗冲击。橄榄球运动员据此相信他的面罩不会裂成碎片。

Plastic deformation is the ability of bend or deform before breaking.As engineers, we usually design materials so that they don’t deform under normal conditions.You don’t want your car to lean to the east after a strong west wind.塑性变形就是在断裂前弯曲或变形的能力。作为工程师，设计时通常要使材料在正常条件下不变形。没有人愿意一阵强烈的西风过后自己的汽车向东倾斜。

However, sometimes we can take advantage of plastic deformation.The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有时我们也能利用塑性变形。汽车上压皱的区域在它们断裂前通过经历塑性变形来吸收能量。The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and

electrical wires.金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。

It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因为这些阶电子吸收到达金属的光子，所以透过金属不可能看得见。没有光子能通过金属。

Alloys are compounds consisting of more than one metal.Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一种以上金属组成的混合物。加一些其它金属能影响密度、强度、断裂韧性、塑性变形、导电性以及环境侵蚀。

For example, adding a small amount of iron to aluminum will make it stronger.Also, adding some chromium to steel will slow the rusting process, but will make it more brittle.例如，往铝里加少量铁可使其更强。同样，在钢里加一些铬能减缓它的生锈过程，但也将使它更脆。

• Ceramics and Glasses 陶瓷和玻璃

A ceramic is often broadly defined as any inorganic nonmetallic material． By this definition, ceramic materials would also include glasses;however, many materials scientists add the stipulation that “ceramic” must also be crystalline.陶瓷通常被概括地定义为无机的非金属材料。照此定义，陶瓷材料也应包括玻璃；然而许多材料科学家添加了“陶瓷”必须同时是晶体物组成的约定。

A glass is an inorganic nonmetallic material that does not have a crystalline structure.Such materials are said to be amorphous.玻璃是没有晶体状结构的无机非金属材料。这种材料被称为非结晶质材料。Properties of Ceramics and Glasses Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性

高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和抗腐蚀性是陶瓷和玻璃的一些有用特性。

Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.许多陶瓷都是电和热的良绝缘体。某些陶瓷还具有一些特殊性能：有些是磁性材料，有些是压电材料，还有些特殊陶瓷在极低温度下是超导体。陶瓷和玻璃都有一个主要的缺点：它们容易破碎。

Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics.Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生产的简单有效的—诸如浇铸和吹制这些涉及熔化的技术都不能用于由晶体物组成的陶瓷的生产。作为替代，一般采用“烧结”或“焙烧”工艺。

In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point.At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained.在烧结过程中，陶瓷粉末先挤压成型然后加热到略低于熔点温度。在这样的温度下，粉末内部起反应去除孔隙并得到十分致密的物品。

In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.为了使核心玻璃有比覆层大的折射指数，在其中掺入微小的、可控数量的能减缓光速而不会吸收光线的杂质或搀杂剂。

The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全内反射现象与核心玻璃的高纯度一样，使光线几乎无强度损耗传递长距离成为可能。

• Composites

复合材料

Composites are formed from two or more types of materials.Examples include polymer/ceramic and metal/ceramic

composites.Composites are used because overall properties of the composites are superior to those of the individual components.复合材料由两种或更多材料构成。例子有聚合物/陶瓷和金属/陶瓷复合材料。之所以使用复合材料是因为其全面性能优于组成部分单独的性能。

For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.Two types of composites are: fiber-reinforced composites and particle-reinforced composites.例如：聚合物/陶瓷复合材料具有比聚合物成分更大的模量，但又不像陶瓷那样易碎。复合材料有两种：纤维加强型复合材料和微粒加强型复合材料。Fiber-reinforced Composites Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers.Fibers increase the modulus of the matrix material.纤维加强型复合材料

加强纤维可以是金属、陶瓷、玻璃或是已变成石墨的被称为碳纤维的聚合物。纤维能加强基材的模量。The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿着纤维长度有很强结合力的共价结合在这个方向上给予复合材料很高的模量，因为要损坏或拉伸纤维就必须破坏或移除这种结合。

Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.把纤维放入复合材料较困难，这使得制造纤维加强型复合材料相对昂贵。

Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix.纤维加强型复合材料用于某些最先进也是最昂贵的运动设备，例如计时赛竞赛用自行车骨架就是用含碳纤维的热固塑料基材制成的。

Body parts of race cars and some automobiles are composites made of glass fibers(or fiberglass)in a thermoset matrix.竞赛用汽车和某些机动车的车体部件是由含玻璃纤维(或玻璃丝)的热固塑料基材制成的。

Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis.Fiber composite manufacturers often rotate layers of fibers to avoid directional variations in the modulus.纤维在沿着其轴向有很高的模量，但垂直于其轴向的模量却较低。纤维复合材料的制造者往往旋转纤维层以防模量产生方向变化。

Particle-reinforced composites Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as

aluminum, and amorphous materials，including polymers and carbon black.微粒加强型复合材料

用于加强的微粒包含了陶瓷和玻璃之类的矿物微粒，铝之类的金属微粒以及包括聚合物和碳黑的非结晶质微粒。

Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix.An example of particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.微粒用于增加基材的模量、减少基材的渗透性和延展性。微粒加强型复合材料的一个例子是机动车胎，它就是在聚异丁烯人造橡胶聚合物基材中加入了碳黑微粒。

• Polymers

聚合材料

A polymer has a repeating structure, usually based on a carbon backbone.The repeating structure results in large chainlike molecules.Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.聚合物具有一般是基于碳链的重复结构。这种重复结构产生链状大分子。由于重量轻、耐腐蚀、容易在较低温度下加工并且通常较便宜，聚合物是很有用的。

Some important characteristics of polymers include their size(or molecular weight), softening and melting points, crystallinity, and structure.The mechanical properties of polymers generally include low strength and high toughness.Their strength is often improved using reinforced composite structures.聚合材料具有一些重要特性，包括尺寸(或分子量)、软化及熔化点、结晶度和结构。聚合材料的机械性能一般表现为低强度和高韧性。它们的强度通常可采用加强复合结构来改善。

Important Characteristics of Polymers Size.Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性

尺寸：单个聚合物分子一般分子量为10,000到1,000,000g/mol之间，具体取决于聚合物的结构—这可以比2,000个重复单元还多。

The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.聚合物的分子量极大地影响其机械性能，分子量越大，工程性能也越好。

Thermal transitions.The softening point(glass transition temperature)and the melting point of a polymer will determine which it will be suitable for applications.These temperatures usually determine the upper limit for which a polymer can be used.热转换性：聚合物的软化点(玻璃状转化温度)和熔化点决定了它是否适合应用。这些温度通常决定聚合物能否使用的上限。

For example, many industrially important polymers have glass transition temperatures near the boiling point of water(100℃, 212℉), and they are most useful for room temperature applications.Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).例如，许多工业上的重要聚合物其玻璃状转化温度接近水的沸点(100℃, 212℉)，它们被广泛用于室温下。而某些特别制造的聚合物能经受住高达300℃(572℉)的温度。

Crystallinity.Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures(semi-crystalline).结晶度：聚合物可以是晶体状的或非结晶质的，但它们通常是晶体状和非结晶质结构的结合物(半晶体)。Interchain interactions.The polymer chains can be free to slide past one another(thermo-plastic)or they can be connected to each other with crosslinks(thermoset or elastomer).Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子链间的相互作用：聚合物的原子链可以自由地彼此滑动(热可塑性)或通过交键互相连接(热固性或弹性)。热可塑性材料可以重新形成和循环使用，而热固性与弹性材料则是不能再使用的。

Intrachain structure.The chemical structure of the chains also has a tremendous effect on the properties.Depending on the structure the polymer may be hydrophilic or hydrophobic(likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.链内结构：原子链的化学结构对性能也有很大影响。根据各自的结构不同，聚合物可以是亲水的或憎水的(喜欢或讨厌水)、硬的或软的、晶体状的或非结晶质的、易起反应的或不易起反应的。

第二单元

The understanding of heat treatment is embraced by the broader study of metallurgy.Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product.对热处理的理解包含于对冶金学较广泛的研究。冶金学是物理学、化学和涉及金属从矿石提炼到最后产物的工程学。

Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties.According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining.热处理是将金属在固态加热和冷却以改变其物理性能的操作。按所采用的步骤，钢可以通过硬化来抵抗切削和磨损，也可以通过软化来允许机加工。

With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior.The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.使用合适的热处理可以去除内应力、细化晶粒、增加韧性或在柔软材料上覆盖坚硬的表面。因为某些元素(尤其是碳)的微小百分比极大地影响物理性能，所以必须知道对钢的分析。

Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper.Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.合金钢的性质取决于其所含有的除碳以外的一种或多种元素，如镍、铬、锰、钼、钨、硅、钒和铜。由于合金钢改善的物理性能，它们被大量使用在许多碳钢不适用的地方。

The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels.With this process the rate of cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect.下列讨论主要针对被称为普通碳钢的工业用钢而言。热处理时冷却速率是控制要素，从高于临界温度快速冷却导致坚硬的组织结构，而缓慢冷却则产生相反效果。

• A Simplified Iron-carbon Diagram 简化铁碳状态图

If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力集中于一般所说的钢上，经常要用到简化铁碳状态图。

Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted.A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.铁碳状态图中靠近三角区和含碳量高于2%的那些部分对工程师而言不重要，因此将它们删除。如图2.1所示的简化铁碳状态图将焦点集中在共析区，这对理解钢的性能和处理是十分有用的。

Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制这一由于奥氏体和铁素体的碳溶解性完全不同而产生的反应，使得通过热处理能获得很大范围的特性。To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in Fig.2.1.At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron.When the steel cools to 727℃(1341℉), several changes occur simultaneously.为了理解这些过程，考虑含碳量为0.77%的共析钢，沿着图2.1的x-x’线慢慢冷却。在较高温度时，只存在奥氏体，0.77%的碳溶解在铁里形成固溶体。当钢冷却到727℃(1341℉)时，将同时发生若干变化。

The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution.铁需要从面心立方体奥氏体结构转变为体心立方体铁素体结构，但是铁素体只能容纳固溶体状态的0.02%的碳。The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C.In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.被析出的碳与金属化合物Fe3C形成富碳的渗碳体。本质上，共析体的基本反应是奥氏体0.77%的碳→铁素体0.02%的碳+渗碳体6.67%的碳。

Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite.Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.由于这种碳成分的化学分离完全发生在固态中，产生的组织结构是一种细致的铁素体与渗碳体的机械混合物。通过打磨并在弱硝酸酒精溶液中蚀刻制备的样本显示出由缓慢冷却形成的交互层状的薄片结构。

This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother-of-pearl at low magnification.这种结构由两种截然不同的状态组成，但它本身具有一系列特性，且因与低倍数放大时的珠母层有类同之处而被称为珠光体。

Steels having less than the eutectoid amount of carbon(less than 0.77%)are known as hypo-eutectoid steels.Consider now the transformation of such a material represented by cooling along line y-y’ in Fig.2.1.含碳量少于共析体(低于0.77%)的钢称为亚共析钢。现在来看这种材料沿着图2.1中y-y’ 线冷却的转变情况。At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite.Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.在较高温度时，这种材料全部是奥氏体，但随着冷却就进入到铁素体和奥氏体稳定状态的区域。由截线及杠杆定律分析可知，低碳铁素体成核并长大，剩下含碳量高的奥氏体。

At 727℃(1341℉), the austenite is of eutectoid composition(0.77% carbon)and further cooling transforms the remaining austenite to pearlite.The resulting structure is a mixture of primary or pro-eutectoid ferrite(ferrite that formed above the eutectoid reaction)and regions of pearlite.在727℃(1341℉)时，奥氏体为共析组成(含碳量0.77%)，再冷却剩余的奥氏体就转化为珠光体。作为结果的组织结构是初步的共析铁素体(在共析反应前的铁素体)和部分珠光体的混合物。

Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon.When such steel cools, as shown in z-z’ of Fig.2.1 the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite.过共析钢是含碳量大于共析量的钢。当这种钢冷却时，就像图2.1的z-z’线所示，除了初步的共析状态用渗碳体取代铁素体外，其余类似亚共析钢的情况。

As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉).As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature.随着富碳部分的形成，剩余奥氏体含碳量减少，在727℃(1341℉)时达到共析组织。就像以前说的一样，当缓慢冷却到这温度时所有剩余奥氏体转化为珠光体。

It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated by slow cooling.With slow heating, these transitions occur in the reverse manner.应该记住由状态图描述的这种转化只适合于通过缓慢冷却的近似平衡条件。如果缓慢加热，则以相反的方式发生这种转化。

However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis.然而，当快速冷却合金时，可能得到完全不同的结果。因为没有足够的时间让正常的状态反应发生，在这种情况下对工程分析而言状态图不再是有用的工具。

• Hardening

淬火

Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.淬火就是把钢件加热到或超过它的临界温度范围，然后使其快速冷却的过程。

If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram.However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range.如果钢的含碳量已知，钢件合适的加热温度可参考铁碳合金状态图得到。然而当钢的成分不知道时，则需做一些预备试验来确定其温度范围。

A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination.When the correct temperature is obtained, there will be a marked change in hardness and other properties.要遵循的合适步骤是将这种钢的一些小试件加热到不同的温度后淬火，再通过硬度试验或显微镜检查观测结果。一旦获得正确的温度，硬度和其它性能都将有明显的变化。

In any heat-treating operation the rate of heating is important.Heat flows from the exterior to the interior of steel at a definite rate.If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained.在任何热处理作业中，加热的速率都是重要的。热量以一定的速率从钢的外部传导到内部。如果钢被加热得太快，其外部比内部热就不能得到均匀的组织结构。

If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking.The heavier the section, the longer must be the heating time to achieve uniform results.如果工件形状不规则，为了消除翘曲和开裂最根本的是加热速率要缓慢。截面越厚，加热的时间就要越长才能达到均匀的结果。

Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.即使加热到正确的温度后，工件也应在此温度下保持足够时间以让其最厚截面达到相同温度。

The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size.In alloy steels the kind and amount of alloying element influences only the hardenability(the ability of the workpiece to be hardened to depths)of the steel and does not affect the hardness except in unhardened or partially hardened steels.通过给定的热处理所得到的硬度取决于淬火速率、含碳量和工件尺寸。除了非淬硬钢或部分淬硬钢外，合金钢中合金元素的种类及含量仅影响钢的淬透性(工件被硬化到深层的能力)而不影响硬度。

Steel with low carbon content will not respond appreciably to hardening treatment.As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases.含碳量低的钢对淬火处理没有明显的反应。随着钢的含碳量增加到大约0.60%，可能得到的硬度也增加。Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state.Pearlite responds best to heat-treating operations;and steel composed mostly of pearlite can be transformed into a hard steel.高于此点，由于超过共析点钢完全由珠光体和退火状态的渗碳体组成，硬度增加并不多。珠光体对热处理作业响应最好；基本由珠光体组成的钢能转化成硬质钢。

As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same.There is a limit to the rate of heat flow through steel.即使所有其它条件保持不变，随着要淬火的零件尺寸的增加其表面硬度也会有所下降。热量在钢中的传导速率是有限的。

Under these circumstances there would always be some finite depth of surface hardening regardless of size.This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.在这种情况下不管零件尺寸如何，其表面总归有一定深度被硬化。但油淬情况就不是如此，因为油淬时在淬火临界阶段零件表面的温度可能仍然很高。

• Tempering

回火

Steel that has been hardened by rapid quenching is brittle and not suitable for most uses.By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions．

快速淬火硬化的钢是硬而易碎的，不适合大多数场合使用。通过回火，硬度和脆性可以降低到使用条件所需要的程度。

As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel.The operation consists of reheating quench-hardened steel to some temperature below the critical range followed by any rate of cooling.随着这些性能的降低，拉伸强度也降低而钢的延展性和韧性则会提高。回火作业包括将淬硬钢重新加热到低于临界范围的某一温度然后以任意速率冷却。

Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would.The final structure obtained from tempering a fully hardened steel is called tempered martensite.虽然这过程使钢软化，但它与退火是大不相同的，因为回火适合于严格控制物理性能并在大多数情况下不会把钢软化到退火那种程度。回火完全淬硬钢得到的最终组织结构被称为回火马氏体。

Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel.Low-temperature draws, from 300℉ to 400℉(150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains.由于马氏体这一淬硬钢主要成分的不稳定性，使得回火成为可能。低温回火，300℉到400℉(150℃~205℃)，不会引起硬度下降很多，主要用于减少内部应变。

As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃)the change to a structure called tempered martensite is very rapid.The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite.随着回火温度的提高，马氏体以较快的速率分解，并在大约600℉(315℃)迅速转变为被称为回火马氏体的结构。回火作业可以描述为渗碳体析出和凝聚或聚结的过程。

A substantial precipitation of cementite begins at 600℉(315℃), which produces a decrease in hardness.Increasing the temperature causes coalescence of the carbides with continued decrease in hardness.渗碳体的大量析出开始于600℉(315℃)，这使硬度下降。温度的上升会使碳化物聚结而硬度继续降低。In the process of tempering, some consideration should be given to time as well as to temperature.Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.在回火过程中，不但要考虑温度而且要考虑时间。虽然大多数软化作用发生在达到所需温度后的最初几分钟，但如果此温度维持一段延长时间，仍会有些额外的硬度下降。

Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated.通常的做法是将钢加热到所需温度并且仅保温到正好使其均匀受热。

Two special processes using interrupted quenching are a form of tempering.In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool.These processes, known as austempering and martempering, result in products having certain desirable physical properties.两种采用中断淬火的特殊工艺也是回火的形式。这两种工艺中，淬硬钢在其被允许冷却前先在一选定的较低温度盐浴淬火。这两种分别被称为奥氏体回火和马氏体回火的工艺，能使产品具有特定所需的物理性能。

• Annealing

退火

The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.退火的主要目的是使坚硬的钢软化以便机加工或冷作。

This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same.通常是非常缓慢地将钢加热到临界温度以上，并将其在此温度下保持到工件全部均匀受热，然后以受控的速率慢慢地冷却，这样使得工件表面和内部的温度近似相同。

This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal.Annealing also relieves internal stresses previously set up in the metal.这过程被称为完全退火，因为它去除了以前组织结构的所有痕迹、细化晶粒并软化金属。退火也释放了先前在金属中的内应力。

The temperature to which a given steel should be heated in annealing depends on its composition;for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram.When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.给定的钢其退火温度取决于它的成分；对碳钢而言可容易地从局部的铁碳合金平衡图得到。达到退火温度后，钢应当保持在此温度等到全部均匀受热。

This usually takes about 45min for each inch(25mm)of thickness of the largest section.For maximum softness and ductility the cooling rate should be very slow, such as allowing the parts to cool down with the furnace.The higher the carbon content, the slower this rate must be.加热时间一般以工件的最大截面厚度计每英寸(25mm)大约需45min。为了得到最大柔软性和延展性冷却速率应该很慢，比如让零件与炉子一起冷下来。含碳量越高，冷却的速率必须越慢。

The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible.加热的速率也应与截面的尺寸及均匀程度相协调，这样才能使整个零件尽可能均匀地加热。

• Normalizing and Spheroidizing 正火和球化

The process of normalizing consists of heating the steel about 50℉ to 100℉

(10℃~40℃)above the upper critical range and cooling in still air to room temperature.正火处理包括先将钢加热到高于上临界区50℉到100℉(10℃~40℃)然后在静止的空气中冷却到室温。This process is principally used with low-and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties.Most commercial steels are normalized after being rolled or cast.退火主要用于低碳钢、中碳钢及合金钢，使晶粒结构更均匀、释放内应力或获得所需的物理特性。大多数商业钢材在轧制或铸造后都要退火。

Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution.If steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time, this structure will be obtained.球化是使渗碳体产生成类似球状分布结构的工艺。如果把钢缓慢加热到恰好低于临界温度并且保持较长一段时间，就能得到这种组织结构。

The globular structure obtained gives improved machinability to the steel.This treatment is particularly useful for hypereutectoid steels that must be machined.所获得的球状结构改善了钢的可切削性。此处理方法对必须机加工的过共析钢特别有用。

• Surface Hardening 表面硬化 Carburizing The oldest known method of producing a hard surface on steel is case hardening or carburizing.Iron at temperatures close to and above its critical temperature has an affinity for carbon.渗碳

最早的硬化钢表面的方法是表面淬火或渗碳。铁在靠近并高于其临界温度时对碳具有亲合力。

The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel.The carbon is gradually diffused to the interior of the part.The depth of the case depends on the time and temperature of the treatment.碳被吸收进金属与铁形成固溶体使外表面转变成高碳钢。碳逐渐扩散到零件内部。渗碳层的深度取决于热处理的时间和温度。

Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke.It is a long process and used to produce fairly thick cases of from 0.03 to 0.16 in.(0.76~4.06mm)in depth.固体渗碳的方法是将要处理的零件与木炭或焦炭这些含碳的材料一起放入密闭容器。这是一个较长的过程，用于产生深度为0.03到0.16 英寸(0.76~4.06mm)这么厚的硬化层。

Steel for carburizing is usually a low-carbon steel of about 0.15% carbon that would not in itself responds appreciably to heat treatment.In the course of the process the outer layer is converted into high-carbon steel with a content ranging from 0.9% to 1.2% carbon.用于渗碳的一般是含碳量约为0.15%、本身不太适合热处理的低碳钢。在处理过程中外层转化为含碳量从0.9%到1.2%的高碳钢。

A steel with varying carbon content and, consequently, different critical temperatures requires a special heat treatment.含碳量变化的钢具有不同的临界温度，因此需要特殊的热处理。

Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then cooled, thus refining the core structure.The steel should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine structure.由于在较长的渗碳过程中钢内部会有些晶粒生长，所以工件应该加热到核心部分的临界温度再冷却以细化核心部分的组织结构。然后重新加热到高于外层转变温度再淬火以生成坚硬、细致的组织结构。

The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point.A third tempering treatment may be used to reduce strains.由于恰好高于低临界温度通常使过共析钢奥氏体化而硬化，所以对外层采用较低的热处理温度。第三次回火处理可用于减少应变。

Carbonitriding Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共渗

碳氮共渗，有时也称为干法氰化或渗碳氮化，是一种表面硬化工艺。通过把钢放在高于临界温度的气体中，让它吸收碳和氮。

Any carbon-rich gas with ammonia can be used.The wear-resistant case produced ranges from 0.003 to 0.030 inch(0.08~ 0.76mm)in thickness.An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels.可以使用任何富碳气体加氨气，能生成厚度从0.003到0.030英寸(0.08~ 0.76mm)的耐磨外层。碳氮共渗的优点之一是加入氮后外层的淬透性极大增加，为使用低价钢提供条件。

Cyaniding Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化

氰化，有时称为液体碳氮共渗，也是一种结合了吸收碳和氮来获得表面硬度的工艺，它主要用于不适合通常热处理的低碳钢。

The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case.The part is then quenched in water or oil to obtain a hard surface.需表面硬化的零件浸没在略高于Ac1温度熔化的氰化钠盐溶液中，浸泡的持续时间取决于硬化层的深度。然后将零件在水或油中淬火。

Case depths of 0.005 to 0.015in.(0.13~0.38mm)may be readily obtained by this process.Cyaniding is used principally for the treatment of small parts.通过这样处理可以容易地获得0.005到0.015英寸(0.13~0.38mm)的硬化深度。氰化主要用于处理小零件。Nitriding Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents.渗氮

渗氮有些类似普通表面硬化，但它采用不同的材料和处理方法来产生坚硬表面成分。

In this process the metal is heated to a temperature of around 950℉(510℃)and held there for a period of time in contact with ammonia gas.Nitrogen from the gas is introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal.这种工艺中金属加热到约950℉(510℃)，然后与氨气接触一段时间。氨气中的氮进入钢内，形成细微分布于金属表面又十分坚固的氮化物。

Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed.氮与某些元素的硬化能力比其它元素大，因此开发了专用的渗氮合金钢。

Aluminum in the range of 1% to 1.5% has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent.The temperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).在钢中含铝1%到1.5%被证明特别合适，它能与氨气结合形成很稳定坚固的成分。其加热温度范围为925℉到1,050℉(495℃~565℃)。

Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range.Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths.液体渗氮利用熔化的氰化物盐，就像气体渗氮，温度保持在低于转化范围内。液体渗氮时在氰化物溶液中加入比氰化及渗碳都较多的氮和较少的碳。

Case thickness of 0.001 to 0.012in.(0.03~0.30mm)is obtained, whereas for gas nitriding the case may be as thick as 0.025 in.(0.64mm).In general the uses of the two-nitriding processes are similar.液体渗氮可以获得厚度为0.001到0.012英寸(0.03~0.30mm)的硬化层，然而气体渗氮则能获得厚0.025英寸(0.64mm)的硬化层。一般而言两种渗氮方法的用途是类似的。

Nitriding develops extreme hardness in the surface of steel.This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening.渗氮在钢表面获得远远超出正常标准的硬度。其硬度范围为900到1,100布氏硬度，这远高于普通表面硬化所获得的硬度。

Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment.It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process.由于渗氮钢的合金比例，它们比普通钢更强，也容易热处理。建议对这种钢在渗氮前先机加工和热处理，因为渗氮后没有剥落并不需要更多的加工。

effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.值得庆幸的是由于渗氮处理一点都不影响内部结构和性能，也无需淬火，所以几乎没有任何产生翘曲、裂缝及变化条件的趋势。这种表面能有效地抵御水、盐雾、碱、原油和天然气的腐蚀反应。

第三单元

Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity.During or after cooling, the cast part is removed from the mold and then processed for delivery.铸造是一种将熔化的金属倒入或注入合适的铸模腔并且在其中固化的制造工艺。在冷却期间或冷却后，把铸件从铸模中取出，然后进行交付。

Casting processes and cast-material technologies vary from simple to highly complex.Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level.铸造工艺和铸造材料技术从简单到高度复杂变化很大。材料和工艺的选择取决于零件的复杂性和功能、产品的质量要求以及成本预算水平。

Castings are parts that are made close to their final dimensions by a casting process.With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made.通过铸造加工，铸件可以做成很接近它们的最终尺寸。回溯6,000年历史，各种各样的铸造工艺就如同科技进步一样处于一个不断改进和发展的状态。

• Sand Casting

砂型铸造

Sand casting is used to make large parts(typically iron, but also bronze, brass, aluminum).Molten metal is poured into a mold cavity formed out of sand(natural or synthetic).砂型铸造用于制造大型零件(具有代表性是铁，除此之外还有青铜、黄铜和铝)。将熔化的金属倒入由型砂(天然的或人造的)做成铸模腔。

The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance.本节讨论砂型铸造工艺，包括型模、浇注口、浇道、设计考虑因素及铸造余量。

The cavity in the sand is formed by using a pattern(an approximate duplicate of the real part), which are typically made out of wood, sometimes metal.The cavity is contained in an aggregate housed in a box called the flask.砂型里的型腔是采用型模(真实零件的近似复制品)构成的，型模一般为木制，有时也用金属制造。型腔整个包含在一个被放入称为砂箱的箱子里的组合体内。

Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages.Cores are placed in the cavity to form holes of the desired shapes.Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold.砂芯是插入铸模的砂型，用于生成诸如孔或内通道之类的内部特征。砂芯安放在型腔里形成所需形状的孔洞。砂芯座是加在型模、砂芯或铸模上的特定区域，用来在铸模内部定位和支撑砂芯。

A riser is an extra void created in the mold to contain excessive molten material.The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.冒口是在铸模内部增加的额外空间，用于容纳过多的熔化金属。其目的是当熔化金属凝固和收缩时往型腔里补充熔化金属，从而防止在主铸件中产生孔隙。

In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1.The parting line or the parting surface is line or surface that separates the cope and drag.在典型砂型铸造的两箱铸模中，上半部分(包括型模顶半部、砂箱和砂芯)称为上型箱，下半部分称为下型箱，见图3.1所示。分型线或分型面是分离上下型箱的线或面。

The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line.The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system.首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型线处放置浇注系统。然后将上型箱与下型箱装配在一起，再把型砂倒入上型箱盖住型模、砂芯和浇注系统。

The sand is compacted by vibration and mechanical means.Next, the cope is removed from the drag, and the pattern is carefully removed.The object is to remove the pattern without breaking the mold cavity.型砂通过振动和机械方法压实。然后从下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破坏型腔。

This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern.This is usually a minimum of 1.5mm(0.060in.), whichever is greater.The rougher the surface of the pattern, the more the draft to be provided.通过设计拔模斜度—型模垂直相交表面的微小角度偏移量—来使取出型模变得容易。拔模斜度最小一般为1.5mm(0.060in.)，只能比此大。型模表面越粗糙，则拔模斜度应越大。

The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity.熔化的金属从浇注杯注入型腔，浇注杯是浇注系统向型腔提供熔化金属的部分。

The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.将浇注系统的垂直部分与浇注杯连接的是浇注口，浇注系统的水平部分称为浇道，最后到多点把熔化金属导入型腔的称为闸道。

Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere.除此之外，还有称为排放口的浇注系统延长段，它为合成气体和置换空气排放到大气提供通道。

The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature.This is achieved by making the pattern oversize.To account for shrinking, the pattern must be made oversize by these factors on the average.These are linear factors and apply in each direction.型腔通常大于所需尺寸以允许在金属冷却到室温时收缩。这通过把型模做得大于所需尺寸来达到。为解决收缩效应，一般而言型模做得比所需尺寸大，必须考虑线性因素并作用于各个方向。

These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting.In addition, different parts of the casting might require different shrinkage allowances.收缩余量仅仅是近似的，因为准确的余量是由铸件的形状和尺寸决定的。另外，铸件的不同部分也可能需要不同的收缩余量。

Sand castings generally have a rough surface sometimes with surface impurities, and surface variations.A machining(finish)allowance is made for this type of defect.砂型铸件一般表面粗糙，有时还带有表面杂质和表面变异。对这类缺陷采用机加工(最后一道工序)的余量。In general, typical stages of sand casting operation include(as shown in Fig.3.2): 1.Patterns are made.These will be the shape used to form the cavity in the sand.一般而言，砂型铸造作业的典型阶段包括(如图3.2所示)： 1.制作型模。做成用于在型砂中形成型腔的形状。

2.Cores may also be made at this time.These cores are made of bonded sand that will be broken out of the cast part after it is complete.3.Sand is mulled(mixed)thoroughly with additives such as bentonite to increase bonding and overall strength.2.同时还要制作砂芯。这些砂芯用粘结砂做成，等铸件完成后将被打碎取出。3.型砂与膨润土之类的添加剂充分地混合以增强连接及整体强度。

4.Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed.A

compaction stage is typically used to ensure good coverage and solid molds.4.型砂在型模周围成形，并根据需要安放闸道、浇道、冒口、排放口和浇注杯等。通常要采取压紧步骤来保证良好的覆盖和坚固的铸型。

Cores may also be added to make concave or internal features for the cast part.Alignment pins may also be used for mating the molds later.Chills may be added to cool large masses faster.安放砂芯来制成铸件的凹形结构或内部特征。为了以后铸模匹配还要用到定位销。对大质量铸件可能需要加入冷却物来使其较快冷却。

5.The patterns are removed, and the molds may be put through a baking stage to increase strength.6.Mold halves are mated and prepared for pouring metal.5.取走型模，将铸模烘焙以增加强度。6.匹配上下铸模，做好浇铸金属的准备。

7.Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range(we don’t want the metal solidifying before the pour is complete).The exact temperature may be closely controlled depending upon the application.7.金属在熔炉或坩埚中预热到高于液化温度的一个合适范围内(不希望金属在浇铸完成前凝固)。确切的温度要根据应用场合严格控制。

Degassing, and other treatment processes may be done at this time, such as removal of impurities(i.e.slag).Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable.在此期间还要进行排气和其它处理步骤，例如去除杂质(即熔渣)。可以加入一定量原先是这种金属铸件的废料再融化—10%是适当的。

8.The metal is poured slowly, but continuously into the mold until the mold is full.9.As the molten metal cools(minutes to days), the metal will shrink and the volume will decrease.During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape.8.将金属缓慢而连续地注满型模。

9.随着熔化金属的冷却(几分钟到几天)，金属收缩体积减小。在此期间熔化金属可能从冒口回流供给零件以保持其形状不变。

10.Once the part starts to solidify small dendrites of solid material form in the part.During this time metal properties are being determined, and internal stresses are being generated.If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.10.在零件开始凝固其内部形成固态金属的小型树枝状结晶期间金属性能被确定，同时也产生了内应力。如果零件以恒定速率冷却得足够缓慢，最终零件将相对均质并释放内应力。

11.Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal

properties.At this point the sand is simply broken up, and the part removed.At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.11.一旦零件在共析点以下完全凝固，可以不考虑金属的最后性能而将其取出。这时可以简单地打碎砂型并取出零件，但零件表面会有大量型砂粘附着，内部还有实心的砂芯。

12.A bulk of the remaining sand and cores can be removed by mechanically striking the part.Other options are to use a vibrating table, sand/shot blaster, hand labor, etc.12.大量的剩余型砂和砂芯要通过机械敲击零件来去除。其它的选择还有采用振动台、喷砂/喷丸机、手工作业等等。

13.The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc.Grinding operations are used to remove any remaining bulk.14.The part is taken down to final shape using machining operations.And cleaning operations may be used to remove oxides, etc.13.最后零件要用刀具、喷枪等切掉浇道闸道系统，这样就接近最终形状了。再用磨削作业去除多余的部分。14.通过机加工将零件切削到最终形状。可能还要用清洗作业去除氧化物等。

• Investment casting 熔模铸造

Investment casting is also known as the lost wax process.This process is one of the oldest manufacturing processes.The Egyptians used it in the time of the Pharaohs to make gold jewelry(hence the name Investment)some 5,000 years ago.熔模铸造也称为失蜡加工。这是最古老的制造工艺之一。大约在5,000年前的法老王时代，埃及人就用它制造黄金饰品(因此而得名投资)。

Intricate shapes can be made with high accuracy.In addition, metals that are hard to machine or fabricate are good candidates for this process.It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures.复杂的形状能被高精度地制造。另外较难机加工或制作的金属都能用此工艺。它还能用于生产一般制造技术无法生产的零件，例如有复杂形状的涡轮叶片或必须耐得住高温的飞机零件。

The mold is made by making a pattern using wax or some other material that can be melted away.This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin.This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.制作铸型的型模采用石蜡或其它一些能被融化掉的材料做成。石蜡型模浸泡在耐热浆里，让它覆盖型模并形成外壳，然后使其变干。重复这个浸泡、变干的过程直至获得足够的厚度。

the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.完成后把整个型模放在烤箱里融化石蜡。这样就做成了能填充熔化金属的铸型。由于这种铸型是环绕整块型模形成的(无需像传统的砂型铸造工艺那样拔模)，能制作十分复杂的零件和浮雕。

The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master.石蜡型模本身能用立体制版或类似的模型复制—这可以采用计算机立体模型原版制作。

The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts.For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder.对较低熔化温度而言，用于耐热浆的材料是石膏作粘合剂和用粉末状硅石作耐温材料的混合物。对较高熔化温度而言，则采用硅线石或氧化铝硅酸盐作耐温材料、无水硅酸作粘合剂。

Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied.The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry.根据最后所需光洁度也可采用硅线石和乙烷基硅酸盐。这样生成的铸模可直接用于薄壁铸件或通过将其放在较大容器内用更多耐热浆加强。

Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉)to remove any residues of wax, harden the binder.The pour in the pre-heated mold also ensures that the mold will fill completely.在正要浇铸之前，将型模预热到约1,000℃(1,832℉)以去除剩余石蜡、硬化粘合剂。在预热的型模中浇铸也能保证型模完全充满。

Pouring can be done using gravity, pressure or vacuum conditions.Attention must be paid to mold permeability when using pressure, to allow the air to escape as the pour is done.浇铸可采用重力、压力或真空条件来实现。当使用压力时必须注意渗透性，以便在浇铸的同时让空气逸出。Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions.Castings can weigh from a few grams to 35kg(0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb).Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.)for alloys that can be cast easily.一般公差可能为长度的0.5%，小尺寸可能低到0.15%。虽然通常尺寸的铸件重量范围为200g到约8kg(7oz到15lb)，但实际可从几克到35kg(0.1oz to 80lb)。对容易铸造的合金而言，通常壁厚约为1mm到0.5mm(0.040~ 0.020 in.)。

The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, stellite, hastelloys, and precious metals.Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.可以用于铸造的材料类型有：铝合金、青铜、工具钢、不锈钢、钨铬钴合金、镍基合金和贵金属。采用熔模铸造的零件常常不需要进一步加工，因为熔模铸造能达到精密的公差。

• Centrifugal Casting 离心铸造

Centrifugal casting(Fig.3.3)as a category includes centrifugal casting, semi-centrifugal casting and centrifuging.In centrifugal casting, a permanent mold is rotated about its axis at high speeds(300 to 3,000rpm)as the molten metal is poured.离心铸造(图3.3)作为一个种类包括了离心铸造、半离心铸造和离心法铸造。离心铸造中，永久性的型模在熔化金属浇铸时以较高速度(300到3,000rpm)绕其轴线旋转。

The molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling.The casting is usually a fine grain casting with a very fine-grained outer diameter, which is resistant to atmospheric corrosion, a typical situation with pipes.The inside diameter has more impurities and inclusions, which can be machined away.受离心力作用熔化金属被抛向型模的内壁，在那里冷却后固化。这种铸件通常为外径处晶粒非常细小的细晶粒铸件，能耐大气腐蚀，典型的情况是管子。内径处则有较多的杂质和内含物，但可用机加工去除。

Only cylindrical shapes can be produced with this process.Size limits are up to 3m(10feet)diameter and 15m(50 feet)length.Wall thickness can be 2.5mm to 125mm(0.1~5.0in.).The tolerances that can be held on the OD can be as good as 2.5mm(0.1in.)and on the ID can be 3.8mm(0.15in.).The surface finish ranges from 2.5mm to 12.5mm(0.1~0.5in.)rms(root-mean-square).只有圆柱形才能用此工艺生产。尺寸限制为直径大到3m(10feet)、长度大到15m(50feet)。壁厚为2.5mm到125mm(0.1~5.0in.)。外径公差保持在2.5mm(0.1in.)以内，内径公差保持在3.8mm(0.15in.)以内。表面粗糙度的有效值(均方根)范围为2.5mm到12.5mm(0.1~0.5in.)。

Typical materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel.Two materials can be cast by introducing a second material during the process.Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axis-symmetric.可用此工艺铸造的典型材料有：铁、钢、不锈钢以及铝、铜和镍的合金。通过在生产过程中加入第二种材料能进行两种材料铸造。采用这种工艺制造的典型零件有：管子、锅炉、压力容器、飞轮、汽缸衬垫和其它轴对称零件。

The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away.This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.零件的中心轴附近存在缺陷和孔隙，因此仅适用于能将这些机加工去除的零件。这种工艺被用于制造车轮、管嘴及类似的随后可用机加工去除中心轴部分的零件。

Centrifuging.Centrifuging is used for forcing metal from a central axis of the equipment into individual mold cavities that are placed on the circumference.This provides a means of increasing the filling pressure within each mold and allows for reproduction of intricate details.This method is often used for the pouring of investment casting pattern.离心法铸造：离心法铸造用于迫使金属从设备的中心轴进入分布在圆周上的单独型腔。它为每个型腔提供了一种增加填充压力方法并允许再现复杂细节。这种方法常用于浇铸熔模铸型。

This can make complex shaped castings without any draft or flash.However, the pattern cost can be high due to the expendable nature of the pattern.Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions.Surface finish can be held from 2.5μm to 25μm(0.1μin.to 1.0μin.)rms(root-mean-square).它能制造没有拔模斜度和缝脊的复杂形状铸件。然而由于型模的消耗特性，型模成本可能较高。最小壁厚为2.5mm，公差能保持在尺寸的0.3% 之内。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之间。

Size limits are from 400g(1lb)to several tons.No draft allowance is required.Typical materials that can be cast with this process are aluminum, iron, steel, nickel alloys, copper alloys.Types of parts that can be made using these processes are pump housings, manifolds, and auto brake components.重量限制从400g(1lb)到数吨。无需留拔模余量。这种工艺所用的典型材料有：铝、铁、钢、镍合金、铜合金。可以采用这些工艺制造的零件类型有泵壳、复式接头和自动刹车部件。

第四单元

• Introduction

引言

Forging is an important hot-forming process.It is used in producing components of all shapes and sizes, from quite small items to large units weighing several tons.锻造是一种重要的热成型工艺。它能用于生产各种形状和尺寸、从很小到重量数吨的零件。

Forging is the process by which metal is heated and is shaped by plastic deformation by suitably applying compressive force.Usually the compressive force is in the form of hammer blows using a power hammer or a press, as shown in Fig.4.1.在锻造过程中先将金属加热，然后施加合适的压力使其塑性变形。通常压力都是以由如图4.1所示的动力锤或压力机提供的锤击形式出现。

Hand forging tools comprise variously shaped hammers.The base on which the work is supported during forging is the anvil.手工锻造工具包括各种不同形状的锤子。在锻造中用于支撑工件的基础是铁砧。

For the semimechanized forging of small to medium-sized components, forging hammers powered by various means are employed.The feature common to all of them is that, like the hand forging hammer, they utilize the energy of a falling weight to develop the pressure needed for shaping the metal.对小到中等尺寸零件的半机械化锻造而言，锻锤可采用多种动力。就其一般特性而言，都象手工锻锤一样，它们均利用落重能量来产生金属成型所需的压力。

Larger components are forged by means of forging presses operated by steam or compressed air or by hydraulic or electric power.Largely automatic forging machines are used for the quantity production of engineering parts.锻造大零件则要用到蒸汽、压缩空气、液力或电力驱动的锻压机。大型的自动化锻机用于工程零件的批量生产。A distinction may be made between open-die forging, usually in the form of hammer forging, and closed-die forging.In hammer forging, the component is shaped by hammer blows aided by relatively simple tools.These may include open dies i.e., dies that do not completely enclose the metal to be shaped.锤锻中常用的开式模锻与闭式模锻是有区别的。在锤锻中零件通过锤击辅之以相对简单的工具成型。其中包括开式锻模，就是不完全封闭被成型金属的模具。

One of the basic operations of hammer forging is the elongation of a piece of metal by stretching with hammer blows, causing it to become thinner and longer.In hand forging the work-piece is usually turned 90°after each blow, in order to forge it thoroughly and prevent its lateral expansion.锤锻的基本操作之一就是通过锤击使金属伸长，促成其变细变长。手工锻造时一般在每次锤击后都转过90°以充分锻打工件并防止横向膨胀。

The opposite of elongation is upsetting, which produces compressive shortening.For example, the diameter of a bar can be increased by heating and hammering axially.与伸长相反的是镦粗，即产生压缩性缩短。例如，棒料的直径可以通过加热和轴向锤击而增大。

More important is closed-die forging, very widely used for mass production in industry, in which the metal is shaped

by pressing between a pair of forging dies.The upper die is usually attached to the ram of a forging press or a forging hammer, while the lower die is stationary.更重要的是闭式模锻，在工业上广泛用于规模生产。闭式模锻中金属在一对锻模之间挤压成型。顶模通常放在锻压机的撞头或锻锤上，而底模则是固定的。

Together they form a closed die.Closed-die forging can produce components of greater complexity and accuracy, with a better surface finish than the more traditional methods not using closed dies.The dies are made of special heat-resistant and wear-resistant tool steels.两者合在一起形成闭式锻模。闭式模锻能生产高度复杂和精确的零件，而且表面光洁度要比不用闭式锻模的更传统方法好。闭式锻模采用特殊的耐热、耐磨工具钢制成。

Closed-die forging is used for the rapid production of large numbers of fairly small parts and also for very large components.For the latter, e.g., modern jet-aircraft components, giant hydraulically operated presses are used, which can develop forces of 50,000 tons and more.闭式模锻用于相当小的零件大批量快速生产，也可用于很大的零件。对后者而言，例如现代喷气飞机零件，使用能产生50,000吨以上压力的巨型液力锻压机。

One valuable feature of forging is that it improves the strength of the metal by refining the structure and making it uniform;so for heavy forgings, such as marine propeller shafts, an immensely powerful hydraulic press squeezes the metal with a force sometimes as great as 10,000 tonnes.锻造有价值的特性之一是它通过使金属组织均匀而改善强度，因此对诸如船舶螺旋桨轴之类的重型锻件，要用能达10,000吨压力的庞大而有力的液压机来挤压金属。

Although the hydraulic forging press is a more expensive piece of equipment than a drop-forge, it has advantages beside those of giving greater strength and more uniform structure to large components.On account of the high pressure and squeezing action, it operates with less noise and vibration than a drop-forge.虽然这种液压锻机比落锤锻造要昂贵得多，但它除了能给予大零件较高的强度和更均匀的组织外还有其它优点。由于较高的压力和挤压作用，它比落锤锻造噪声及振动都小得多。

As ingots of steel weighing 30 tonnes or more are forged in this way, manual operation is impossible and it is essential that all the manipulation of the ingot is done mechanically.由于这种情况下被锻钢坯重量大于30吨，人工操作是不可能的，钢坯的所有操作都必须是机械化的。Forging refines the grain structure and improves physical properties of the metal.With proper design, the grain flow

can be oriented in the direction of principal stresses encountered in actual use.铸造细化金属的晶粒组织、改善其物理性能。通过适当的设计，可以使晶粒流动方向与实际使用时的主应力方向一致。

As shown in Fig.4.2, grain flow is the direction of the pattern that the crystals take during plastic deformation.Physical properties(such as strength, ductility and toughness)are much better in a forging than in the base metal, which has crystals randomly oriented.如图4.2所示，晶粒流动的方向就是在塑性变形期间结晶排列的方向。锻件的物理性能(如强度、延展性和韧性)远好于基础金属，因为基础金属的晶粒是无序排列的。

Forgings are consistent from piece to piece, without any of the porosity, voids, inclusions and other defects.Thus, finishing operations such as machining

do not expose voids, because there aren’t any.Also coating operations such as plating or painting are straightforward due to a good surface, which needs very little preparation.锻件各部分是连贯一致的，没有孔隙、空洞、杂质及其它缺陷。因此像机加工之类的精加工工序不会受空洞的影响，因为根本就不存在。另外由于锻件良好的表面，像电镀或油漆之类的涂装工序就很简单，几乎不需要做准备工作。

Forgings yield parts that have high strength to weight ratio, thus are often used in the design of aircraft frame members.A forged metal can result in the following: 锻造生产的零件具有较高的强度重量比，所以常被用在飞机结构零件的设计中。锻造金属可以导致下列结果：

• Increase length, decrease cross-section, called drawing out the metal.• Decrease length, increase cross-section, called upsetting the metal.• Change length, change cross-section, by squeezing in closed impression dies.This results in favorable grain flow for strong parts.●增加长度、减小横截面，称为延伸金属。●减小长度、增加横截面，称为镦粗金属。●通过用封闭锻模挤压，改变长度和横截面。这导致有利的晶粒流使零件坚固。

• Common Forging Processes 常用的锻造工艺

The metal can be forged hot(above recrystallization temperatures)or cold.金属既可热锻(高于再结晶温度)也可冷锻。

what a traditional blacksmith does, and is an old manufacturing process.开式模锻/手工锻：开式模锻或手工锻就是操作者操纵工件在开式锻模中反复击打。完成的产品是锻模的粗糙近似物。这就是传统铁匠干的活，是较古老的制造工艺。

Impression die forgings/Precision forgings.Impression die forgings and precision forgings are further refinements of the blocker forgings.The finished part more closely resembles the die impression.压模锻/精密锻：压模锻和精密锻是雏形模锻的进一步改进。完成的零件与模膛更相似。

Press forgings.Press forgings use a slow squeezing action of a press, to transfer a great amount of compressive force to the workpiece.Unlike an open-die forging where multiple blows transfer the compressive energy to the outside of the product, press forging transfers the force uniformly to the bulk of the material.压锻：压锻通过压力机缓慢的挤压动作将巨大的压力传递给工件。不像开式模锻那样需要多次击打把压缩能量传递到零件外表面，压锻能将力均匀地传递给材料的主体。

This results in uniform material properties and is necessary for large weight forgings.Parts made with this process can be quite large as much as 125kg(260lb)and 3m(10 feet)long.这使材料性能一致，对大重量锻件而言是十分必要的。采用此工艺生产的零件重量可达125kg(260lb)而长度可达3m(10 feet)。

Upset forgings.Upset forging increases cross-section by compressing the length, this is used in making heads on bolts and fasteners, valves and other similar parts.顶锻：顶锻通过压缩长度增加横截面，用于在螺栓等紧固件、柱塞及类似零件上制造头部。

Roll forgings.In roll forging, a bar stock, round or flat is placed between die rollers which reduces the cross-section and increases the length to form parts such as axles, leaf springs etc.This is an essential form of draw forging.滚锻：在滚锻时，圆的或是扁平的棒料放在模辊之间缩小横截面增加长度制成诸如轮轴、板簧之类的零件。这是轧锻的基本形式。

Swaging.Swaging—a tube or rod is forced inside a die and the diameter is reduced as the cylindrical object is fed.The die hammers the diameter and causes the metal to flow inward causing the outer diameter of the tube or the rod to take the shape of the die.型锻：型锻—将圆管或圆棒强制压入锻模，随着圆柱形物体的被压入其直径减小。锻模锤击横断面使金属向内流动导致圆管或圆棒的外径变为锻模的形状。

Net shape/Near-net shape forging.In net shape or near-net shape forging, forging results in wastage of material in the form of material flash and subsequent machining operations, as shown in Fig.4.3.This wastage can be as high as 70% for gear blanks, and even 90% in the case of aircraft structural parts.纯型/近似纯型锻：采用纯型锻或近似纯型锻，产生材料损耗的主要形式是飞边以及随后的机加工，如图4.3所示。齿轮毛坯材料损耗为70%，而飞机结构零件的材料损耗甚至达90%。

Net-shape and near-net-shape processes minimize the waste by making precision dies, producing parts with very little draft angle(less than 1°).These types of processes often eliminate or reduce machining.纯型锻和近似纯型锻工艺通过制作精密模具并生产锻模斜角很小(小于1°)的零件能使材料损耗最小化。此类工艺通常可以省去或减少机加工。

The processes are quite expensive in terms of tooling and the capital expenditure required.Thus, these processes can be only justified for current processes that are very wasteful where the material savings will pay for the significant increase in tooling costs.从模具的角度而言这些工艺是相当昂贵的，需要资金投入。因此这些工艺只有对目前很浪费的生产过程，在材料节约足以补偿模具成本的大量增加时才是合理的。

• Die Design Consideration 锻模设计的考虑因素

• Parting surface should be along a single plane if possible, else following the contour of the part.The parting surface should be through the center of the part, not near the upper or lower edges.• 如果可能分模面应沿着单一平面，否则就顺着零件轮廓方向。分模面应经过零件中心，而不要靠近上下边缘。

If the parting line cannot be on a single plane, then it is good practice to use symmetry of the design to minimize the side thrust forces.Any point on the parting surface should be less than 75°from the principal parting plane.如果分模面不能在单一平面，利用设计的对称性来减小侧向推力不失为一种好方法。分模面上任意点与主分模面的夹角应小于75°。

• As in most forming processes, use of undercuts should be avoided as these will make the removal of the part difficult, if not impossible.• 如同大多数成型工艺，如果不是非用不可，尽量避免采用凹槽，因为凹槽会使零件难以取出。• Generous fillets and radius should be provided to aid in material flow during the forging process.Sharp corners are stress-risers in the forgings, as well as make the dies weak in service.• Ribs should not be high or narrow;this makes it difficult for the material to flow.• 应提供尽可能大的倒角和半径以帮助材料在锻造过程中流动。锐角会增加锻件中的应力，同时在使用时削弱锻模。

• 加劲肋不要过高、过窄，因为这会造成材料流动困难。• Tolerances

公差

• Dimension tolerances are usually positive and are approximately 0.3% of the dimension, rounded off to the next higher 0.5mm(0.020in.).• 尺寸公差通常为正，大约取为该尺寸的0.3%，并圆整到较大的0.5mm(0.020in.)。

• Die wear tolerances are lateral tolerances(parallel to the parting plane)and are roughly +0.2% for copper alloys to +0.5% for aluminum and steel.• 锻模磨损公差为侧向公差(平行于分模面)，对铜合金大约为+0.2%，对铝和钢大约为+0.5%。• Die closure tolerances are in the direction of opening and closing, and range from 1mm(0.040in.)for small forgings, die projection area＜150cm2(23in.2), to 6.25mm(0.25in.)for large forgings, die projection area＞6,500cm2(100in.2).• 锻模的闭合公差处于开闭的方向上，范围从对较小锻件[其投影面积＜150cm2(23in.2)]取为1mm(0.040in.)，到较大锻件[其投影面积＞6,500cm2(100in.2)]取为6.25mm(0.25in.)。

• Die match tolerances are to allow for shift in the upper die with respect to the lower die.• 锻模的配合公差是为了允许上模能根据下模替换。

A proper lubricant is necessary for making good forgings.The lubricant is useful in preventing sticking of the workpiece to the die, and also acts as a thermal insulator to help reduce die wear.制造良好的锻件必须有合适的滑润剂。滑润剂对防止工件粘住锻模很有用，还可以作为绝热体帮助减少锻模磨损。

第五单元

Powder metallurgy(Fig.5.1)uses sintering process for making various parts out of metal powder.The metal powder is compacted by placing in a closed metal cavity(the die)under pressure.粉末冶金(图5.1)采用烧结工艺将金属粉末制成各种各样的零件。金属粉末放在封闭的金属腔(模具)中在压力下被压实。

This compacted material is placed in an oven and sintered in a controlled atmosphere at high temperatures and the metal powders coalesce and form a solid.A Second pressing operation, repressing, can be done prior to sintering to improve the compaction and the material properties.被压实的材料置于炉内烧结，在高温下炉内环境可控，金属粉末熔合形成固体。在烧结前可以进行二次挤压作

业(再挤压)以改善压实状态和材料性能。

Powder metallurgy is a highly developed method of manufacturing reliable ferrous and nonferrous parts.Made by mixing elemental or alloy powders and compacting the mixture in a die, the resultant shapes are then sintered or heated in a controlled atmosphere furnace.粉末冶金是一种高度发达的制造可靠铁或非铁零件的方法。通过混合元素或合金粉末并在模具中压实混合物，再烧结或在环境可控炉内加热制成最终形状。

• Material

材料

Elemental powders, such as iron and copper, are easy to compress to relatively high densities, produce pressed compacts with adequate strength for handling during sintering, but do not produce very high strength sintered parts.诸如铁、铜之类的单一元素粉末较容易被压得相对密度较高、生产具备足够强度的压制物供烧结处理，但是无法制造出很高强度的烧结零件。

Pre-alloyed powders are harder, less

compressible and hence require higher pressing loads to produce high density compacts.However, they are capable of producing high strength sintered materials.预先合金粉末比较硬、不容易压实，因此需要较高的挤压力来产生高密度的压制物。然而它们能生成高强度烧结材料。

Pre-alloying is also used when the production of a homogeneous material from elemental powders requires very high temperatures and long sintering times.The best examples are the stainless steels, whose chromium and nickel contents have to be pre-alloyed to allow economic production by powder metallurgy.如果用单一元素粉末生产均匀材料需要很高温度和较长烧结时间，也可用预先合金。最好的例子是不锈钢，因含有铬和镍成分，所以粉末冶金必须用预先合金才经济。

Partially alloyed powders are a compromise approach.Elemental powders, e.g.iron with 2wt.% copper, are mixed to produce an homogeneous blend which is then partially sintered to attach the copper particles to the iron particles without producing a fully diffused powder but retaining the powder form.部分合金粉末是一种折衷的方法。单一元素粉末，例如铁与2%的铜(重量百分比)混合均匀，经部分烧结后铜微粒粘附到铁微粒上而没有产生充分扩散的粉末却保留了粉末的形态。

In this way the compressibilities of the separate powders in the blend are maintained and the blend will not segregate during transportation and use.用这种方法混合物中单独粉末的可压缩性得以维持，在运送和使用期间结合将不会分离。

A similar technique is to “glue” the small percentage of alloying element onto the iron powder.This “glueing”

technique is successfully used to introduce carbon into the blends, a technique which prevents carbon segregation and dusting, producing so-called “clean” powders.另一种类似的技术是把小百分比的合金元素“粘合”到铁微粒上。这种“粘合”技术已成功用于将碳引入结合物，一种防止碳分离并起尘的技术，生产所谓的“清洁”粉末。

• Powder Consolidation 粉末合成

Components or articles are produced by forming a mass of powder into a shape, then consolidating to form inter-particle metallurgical bonds.通过将大量的粉末放入模具成型为零件或物品，然后合成为内有微粒的冶金结合物。

An elevated temperature diffusion process referred to as sintering, sometimes assisted by external pressure, accomplishes this.The material is never fully molten, although there might be a small volume fraction of liquid present during the sintering process.Sintering can be regarded as welding the particles present in the initial useful shape.提升温度扩散工艺被称为烧结，有时还辅之以外界的压力来达到目的。虽然在烧结过程中可能会有少量液态出现，但材料决不是全熔化。烧结可以被看作是把微粒焊接成初始的有用形状。

As a general rule both mechanical and physical properties improve with increasing density.Therefore the method selected for the fabrication of a component by powder metallurgy will depend on the level of performance required from the part.Many components are adequate when produced at 85~90% of theoretical full density whist others require full density for satisfactory performance.作为普遍规律，随着密度的增加机械和物理性能均改善。因此选择何种粉末冶金方法来制作零件取决于其所需的性能级别。许多零件只需理论全密度的85~90%而其它的则需全密度才能满足要求。

Some components, in particular bush type bearings often made from copper and its alloys, are produced with significant and controlled levels of porosity, the porosity being subsequently filled with a lubricant.Fortunately there is a wide choice of consolidation techniques available.有些零件，尤其是衬套式轴承常用铜及其合金制作，控制多孔性程度的意义重大，因为这些孔随后要填充润滑剂。

还好有多种合成技术可供选择。Cold Uniaxial Pressing Elemental metal, or an atomized pre-alloyed powder is mixed with a lubricant, typically lithium stearate(0.75 wt.%), and pressed at pressures of say, 600MPa(87,000lb/in.2)in metal dies.冷单向挤压

单一元素金属，或极小颗粒的预先合金粉末与润滑剂(一般是锂硬脂酸盐，重量百分比0.75%)混合，然后在金属模具中施加压力[比如600MPa(87,000lb/in.2)]挤压。

Cold compaction ensures that the as-compacted, or “green”, component is dimensionally very accurate, as it is moulded precisely to the size and shape of the die.冷挤压能保证被压制或“未加工”的零件尺寸十分精确，因为它被精确地按模具的尺寸和形状成型。One disadvantage of this technique is the differences in pressed density that can occur in different parts of the component due to particle/particle and die wall/particle frictional effects.Typical as-pressed densities for soft iron components would be 7.0g/cc, i.e.about 90% of theoretical density.这种技术的缺点之一是由于微粒/微粒和模壁/微粒间的摩擦效应，零件不同部位的压实密度存在差异。典型的软铁零件压制密度为7.0g/cc，即大约是理论密度的90%。

Compaction pressure rises significantly if higher as-pressed densities are required, and this practice becomes uneconomic due to higher costs for the larger presses and stronger tools to withstand the higher pressures.如果需要较高的压实密度则压实压力要显著提高，因为大型压力机成本较高并且在较高压力下模具强度要更高这样就不合算。

Cold Isostatic Pressing Metal powders are contained in an enclosure e.g.a rubber membrane or a metallic can that is subjected to isostatic, which is uniform in all directions, external pressure.As the pressure is isostatic the as-pressed component is of uniform density.冷均衡挤压

金属粉末装入均衡受压的橡胶膜或金属罐内，其所受外压力在各个方向都是均匀的。由于压力是均衡的，所以压制零件密度是均匀的。

Irregularly shaped powder particles must be used to provide adequate green strength in the as-pressed component.This will then be sintered in a suitable atmosphere to yield the required product.必须采用不规则形状粉末微粒为压制零件提供足够的未加工强度。然后放入合适的环境中烧结成所需产品。Normally this technique is only used for semi-fabricated products such as bars, billets, sheet, and roughly shaped components, all of which require considerable secondary operations to produce the final, accurately dimensioned component.通常这种技术只用于制作诸如棒料、坯段、薄板及粗糙成型零件之类的半成品，所有这些都需要大量进一步加工才能生产出最终尺寸精确的零件。

Again, at economical working pressures, products are not fully dense and usually need additional working such as hot extrusion, hot rolling or forging to fully density the material.此外使用经济工作压力的产品不是充分致密的，一般需要增加诸如热挤压、热轧或锻之类的额外工序来使材料达到全密度。

Sintering

Sintering is the process whereby powder compacts are heated so that adjacent particles fuse together, thus resulting in a solid article with improved mechanical strength compared to the powder compact.烧结

烧结就是通过把粉末压制物加热使邻近的微粒熔合在一起的工艺，它能生成比粉末压制物机械强度更好的固体物。

This “fusing” of particles results in an increase in the density of the part and hence the process is sometimes called densification.There are some processes such as hot isostatic pressing which combine the compaction and sintering processes into a single step.微粒的“熔合”导致零件密度增加，因此该工艺有时被称为致密化。还有一些工艺如热均衡挤压，将压实和烧结工艺合并为单一步骤。

After compaction the components pass through a sintering furnace.This typically has two heating zones, the first removes the lubricant, and the second higher temperature zone allows diffusion and bonding between powder particles.零件压实后通过烧结炉。一般有两个加热区，第一个去除润滑剂，第二个温度更高的区域让粉末微粒之间扩散并结合。

A range of atmospheres, including vacuum, are used to sinter different materials depending on their chemical compositions.As an example, precise atmosphere control allows iron/carbon materials to be produced with specific carbon compositions and mechanical properties.根据不同材料的化学成分，烧结的环境包括真空状态也各不相同。例如精确的环境控制可使铁/碳材料生成特殊碳化物和机械性能。

The density of the component can also change during sintering, depending on the materials and the sintering temperature.These dimensional changes can be controlled by an understanding and control of the pressing and sintering parameters, 根据材料和烧结温度的不同，零件的密度在烧结过程中也会改变。因为尺寸的变化可以通过了解并调节挤压及烧结参数进行控制，and components can be produced with dimensions that need little or no rectification to meet the dimensional tolerances.Note that in many cases all of the powder used is present in the finished product, scrap losses will only occur when secondary machining operations are necessary.所以零件尺寸几乎无需校正就能满足尺寸公差。可以看到在很多情况下所有使用的粉末都包含在制成品中，废料损失仅产生于需要辅助机加工时。

Hot Isostatic Pressing Powders are usually encapsulated in a metallic container but sometimes in glass.The container is evacuated, the powder out-gassed to avoid contamination of the materials by any residual gas during the consolidation stage and

sealed-off.热均衡挤压

粉末通常封装在金属容器内有时也装在玻璃容器内。把容器抽真空，粉末抽气是为了防止材料在合成阶段和密封时被残留气体污染。

It is then heated and subjected to isostatic pressure sufficient to plastically deform both the container and the powder.再加热并施加均衡压力足以使容器和粉末都塑性变形。

The rate of densification of the powder depends upon the yield strength of the powder at the temperatures and pressures chosen.At moderate temperature the yield strength of the powder can still be high and require high pressure to produce densification in an economic time.粉末致密率取决于该粉末在选定温度和压力下的屈服强度。中等温度下粉末的屈服强度仍然较高，因此需要较高压力使其在经济时间内致密化。

Typical values might be 1120℃ and 100MPa for ferrous alloys.By pressing at very much higher temperatures lower pressures are required as the yield strength of the material is lower.Using a glass enclosure atmospheric pressure(15psi)is used to consolidate bars and larger billets.对铁合金典型的数值为1120℃和100MPa。由于很高温度下材料的屈服强度较低，因此只需较低压力就能挤压。采用玻璃容器时可用大气压力(15psi)合成棒料和较大坯段。

The technique requires considerable financial investment as the pressure vessel has to withstand the internal gas pressure and allow the powder to be heated to high temperatures.因为压力容器必须经受住内气压并允许粉末加热到较高温度，所以这种技术需要相当可观的资金投入。As with cold isostatic pressing only semi-finished products are produced, either for subsequent working to smaller sizes, or for machining to finished dimensions.此工艺与采用冷均衡挤压一样只能生产半成品，可以通过后续加工至较小尺寸，也能用机加工到最终尺寸。Hot Forging(Powder Forging)Cold pressed and sintered components have the great advantage of being close to final shape(near-net shape), but are not fully dense.Where densification is essential to provide adequate mechanical properties, the technique of hot forging, or powder forging, can be used.热锻(粉末锻造)冷挤压和烧结零件主要优点是接近最终形状(近似纯形)，但不是充分致密的。当为了提供足够的机械性能而致密化是必须时，可以采用热锻或粉末锻造技术。

In powder forging an as-pressed component is usually heated to a forging temperature significantly below the usual sintering temperature of the material and then forged in a closed die.This produces a fully dense component with the shape of the forging die and appropriate mechanical properties.在粉末锻造中，压制零件一般加热到远低于该材料通常烧结温度的锻造温度，然后在闭模中锻造。这能生产具有锻模形状和合适机械性能的充分致密零件。

Powder forged parts generally are not as close to final size or shape as cold pressed and sintered parts.These results from the allowances made for thermal expansion effects and the need for draft angles on the forging tools.Further, minimal machining is required but when all things are considered this route is often very cost-effective.粉末锻造零件通常不像冷挤压和烧结零件那样接近最终尺寸或形状。这是由于为热膨胀效应而设置允差以及在锻模上需要拔模斜角所致。此外还需少量机加工，但全面考虑这种方法通常还是很划算的。

Metal Injection Moulding(MIM)Injection moulding is very widely used to produce precisely shaped plastic components in complex dies.As injection pressures are low it is possible to manufacture complex components, even some with internal screw threads, by the use of side cores and split tools.金属注塑成型(MIM)注塑成型被很广泛地用于在复杂模具中生产形状精确的塑料零件。注塑压力较低使得制作复杂零件成为可能，通过采用侧面型芯和分离工具甚至可以带有内螺纹。

By mixing fine, typically less than 20 μm diameter, spherical metal powders with thermoplastic binders, metal filled plastic components can be produced with many of the features available in injection moulded plastics.After injection moulding, the plastic binder material is removed to leave a metal skeleton which is then sintered at high temperature.将细小(直径一般小于20μm)球形金属粉末与热塑性粘合剂混合，能生产具有多数注塑成型塑料特征的金属充满塑料零件。注塑成型后，去除塑料粘合材料剩下金属骨架，然后在高温下烧结。

Dimensional control can be exercised on the as-sintered component as the injected density is sensibly uniform so shrinkage on sintering is also uniform.烧结零件可以实现尺寸控制，因为注塑密度明显均匀，所以烧结收缩也是均匀的。

Shrinkage can be large, due to both the fine particle size of the powders and the substantial proportion of polymer binder used.由于所用粉末细小微粒的尺寸和聚合物粘合剂的真实比例，收缩可以比较大。

• Features

特征

• For high tolerance parts, a sintering part is put back into a die and repressed.In genera this makes the part more accurate with a better surface finish.• 对较大公差的零件，烧结后可放回模具重新挤压。一般而言这会使零件更精确同时具有更好的表面光洁度。

• A part has many voids that can be impregnated.One method is to use an oil bath.Another method uses vacuum first, then impregnation.• 零件有许多可供填充的空间。一种方法是采用油浴。另一种方法是先抽真空然后再充满。• A part surface can be infiltrated with a low melting point metal to increase density, strength, hardness, ductility and impact resistance.• Plating, heat treating and machining operations can also be used.• 零件表面能被低熔点金属渗透以增大密度、强度、硬度、延展性和抗冲击能力。• 仍然可以进行电镀、热处理和机加工作业。• Advantages

优点

• Good tolerances and surface finish • Highly complex shapes made quickly • Can produce porous parts and hard to manufacture materials(e.g.cemented oxides)• 良好的公差和表面光洁度 • 高度复杂的形状能快速制作

• 能制作多孔零件和难以加工材料(如粘结氧化物)• Pores in the metal can be filled with other materials/metals • Surfaces can have high wear resistance • Porosity can be controlled • Low waste • Automation is easy • 金属中的气孔可用其它材料/金属填充 • 表面能具有较高的耐磨性 • 孔隙率可以控制 • 较低损耗 • 容易自动化

• Physical properties can be controlled • Variation from part to part is low • Hard to machine metals can be used easily • No molten metals • 物理性能可以控制 • 零件之间的变化较小

• 难以机加工的金属能被容易使用 • 无需熔化金属

• No need for many/any finishing operations

• Permits high volume production of complex shapes • Allows non-traditional alloy combinations • Good control of final density • 不需要很多/任何修整作业 • 允许加工复杂形状的大体积产品 • 允许非传统合金结合 • 对最终密度能很好地控制 • Disadvantages

缺点

• Metal powders deteriorate quickly when stored improperly • Fixed and setup costs are high • Part size is limited by the press and compression of the powder used • 如果存放不当金属粉末质量很快降低 • 安装和调整的成本较高

• 零件尺寸受压力机和所用粉末压缩的限制

• Sharp corners and varying thickness can be hard to produce • Non-moldable features are impossible to produce • 锐角和变厚度较难加工 • 不适合模压的东西不可能生产

第六单元

Injection molding(Fig.6.1)is the predominant process for fabrication of thermoplastics into finished forms, and is increasingly being used for thermosetting plastics, fiber-filled composites, and elastomers.注塑成型(图6.1)是将热塑性塑料制成最终形状的主要工艺，并且越来越多地用于热硬化性塑料、纤维填充合成物和人造橡胶。

It is the process of choice for tremendous variety of parts ranging in weight from 5g to 85kg.It is estimated that 25% of all thermoplastics are injection molded.它是重量范围为5g到85kg极大一类零件可选用的工艺。估计所有热塑性塑料中有25%是采用注塑成型的。If newer modifications, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase.如果考虑到新近的改进(例如反作用注塑成型)和采用塑料替代金属的高增长率，注塑成型在世界范围的工业重

要性很可能将继续增加。

Currently, probably close to half of all major processing units is injection molding machines.In 1988, a dollar sale of new injection molding machinery in the U.S.was approximately 65% of total major polymer machinery sales volume;this included 4,600 injection molding units.当前，大概所有主要处理设备的近一半是注塑成型机。1988年，美国新的注塑成型机械销售约占全部主要聚合物机械销售量的65%，其中包括4,600台注塑成型设备。

The machines and their products are ubiquitous and are synonymous with plastics for many people.这类机械和它们的产品普遍存在，对许多人来说与塑料是同义的。

A reciprocating screw injection molding machine combines the functions of an extruder and a compressive molding press.往复螺旋注射成型机把压出机和成型压力机的功能结合起来。

It takes solid granules of thermoplastic resin, melts and pressurizes them in the extruder section, forces the melt at high velocity and pressure through carefully designed flow channels into a cooled mold, then ejects the finished part(s), and automatically recycles.把热塑性塑料树脂的固体颗粒在压出部分融化并增压，迫使其高速融化并通过仔细设计的流动通道进入冷却模具，喷射成最终零件，然后自动再循环。

This machine is a descendant of the plunger type “stuffing machine” patented by the Hyatt brothers in 1872 to mold celluloid.In 1878, the Hyatts developed the first multicavity mold, but it was not until 1938 that Quillery(France)patented a machine incorporating a screw to plasticize the elastomer being molded.这种机械是1872年Hyatt兄弟获得专利权的融化赛璐珞的活塞型“填充机”的派生物。1878年Hyatt兄弟开发了第一个多槽模具，但直到1938年Quillery(法国)才发明了用螺旋增塑人造橡胶并使其成型的一体化机械。

In 1956, Ankerwerk Nuremberg commercialized the modern reciprocating screw injection molding machine for thermoplastics.Today, over 50 machine manufacturers are listed in Modern Plastics Encyclopedia, offering machines to the U.S.market ranging from 2 to 6,000 tons clamping capacity.1956年，Ankerwerk Nuremberg使用于热塑性塑料的现代往复螺旋注塑成型机商业化。今天，已有超过50家制造商列入现代塑料制品百科全书，能为美国市场提供压制能力从2到6,000吨的机械。

(A machine with a 10,000-ton capacity has been built to mold 264-gallon HDPE trash containers.)A host of suppliers of auxiliary equipment, molds, instruments, and controls service this major segment of the polymer industry.(一台能力为10,000吨用于成型264加仑高密度聚乙烯垃圾箱的机械也已制成)。许多辅助设备、模具、仪器和控制系统供应商在为聚合物工业的这一主要部分服务。

course, the integration of materials science and process engineering.注塑成型对深入研究很有价值，因为它结合了许多重要领域，如挤压、模具设计、流变学、完备的液压和电子控制、机器人配件、复杂产品的设计，当然还有材料科学与加工工程的综合。

The objectives of injection molding engineers are simple enough: to obtain minimum cycle time with minimum scrap, to attain specified product performance with assurance, to minimize production costs due to downtime or any other reasons, and to steadily increase in expertise and competitiveness.注塑成型工程师的目标很简单：在最少废料的情况下取得最小循环时间，在有保证的情况下获得指定产品性能，将由停工或其它原因产生的生产成本最小化，还有稳定地增加专门知识和竞争力。

Profit margins for custom injection molders are said to be generally skimpy;an established way to improve profits is to be selected for more demanding, higher margin jobs that demand the highest level of efficiency and competence.传统的注塑成型机利润盈余据说一般是不足的；为了更多需求及更高盈余工作需要选择一种改善利润的确定方法，它要求最高水平的效率和能力。

This text will concentrate on the reciprocating screw machine for thermoplastics, which has largely replaced the older reciprocating plunger types except for very small-capacity machines.本文将集中论述热塑性塑料用的往复螺旋机，除了小容量机械外它已在很大程度上取代了较老的往复活塞式机械。

• Injection Molding Materials 注塑成型材料

It is not possible to injection-mold all polymers.Some polymers like PTFE(Poly-tetra-fluoro-ethylene), cannot be made to flow freely enough to make them suitable for injection molding.要注塑成型所有聚合物是不可能的。像聚四氟乙烯之类的聚合物就不能自由流动得足以适合注塑成型。Other polymers, such as a mixture of resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process.In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.其它聚合物，例如树脂和编织的或垫子形的玻璃纤维的混合物，由于它们的物理性质不适合使用此工艺。一般而言，能进入流动状态的聚合物都可以注塑成型。

The vast majority of injection molding is applied to thermoplastic polymers.This class of materials consists of polymers which always remain capable of being softened by heat and of hardening on cooling, even after repeated cycling.注塑成型的绝大多数都用于热塑性聚合物。这类材料由具有加热软化、冷却硬化甚至可重复循环能力的聚合物组成。

into any shape cavity, and then cooled to become a solid again.这是由于这类材料的长链分子总是保持分离的实体并不相互形成化学连结。一辆由冰块制成的模拟汽车，可以融化(即转化为液态)，倒入任何形状的空腔，然后冷却重新变成固体。

This property differentiates thermoplastic materials from thermosetting ones.In the latter type of polymer, chemical bonds are formed between the separate molecule chains during processing.In this case the chemical bonding referred to as cross linking is the hardening mechanism.这个特性将热塑性材料与热硬化性材料区分开。后者在加工过程中分离的分子链之间形成化学连结。在此情况下作为交联的化学连结是硬化机制。

Crystalline polymers have an ordered molecular arrangement, with a sharp melting point.Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque.结晶质聚合物具有规则的分子排列及明显的熔点。由于规则的分子排列，结晶质聚合物能反射大多数特定光线并一般表现为不透明的。

They also undergo a high shrinkage or reduction in volume during solidification.Crystalline polymers usually are more resistant to organic solvents and have good fatigue and wear-resistant properties.Crystalline polymers also generally are denser and have better mechanical properties than amorphous polymers.它们在固化过程中收缩较大或体积减少较多。结晶质聚合物通常多能抵御有机溶剂并具有良好的抗疲劳和磨损特性。结晶质聚合物通常也比非结晶质聚合物更致密并且具有更好的机械性能。

The main exception to this rule is polycarbonate, which is the amorphous polymer of choice for high quality transparent moldings, and has excellent mechanical properties.其中主要例外是聚碳酸酯，它是可选用做高质量透明注塑件的非结晶质聚合物，并具有卓越的机械性能。The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement.This takes the form of short-chopped fibers, a few millimeters in length, which are randomly mixed with the thermoplastic resin.就本质而言，热塑性塑料的机械性能低于金属，但可以通过加入玻璃纤维强化予以增强来适应某些运用。常用几毫米长的短碎纤维随机地与热塑性树脂混合。

The fibers can occupy up to one third of the material volume to considerably improve the material strength and stiffness.The negative effect of this reinforcement is usually a decrease in impact strength and an increase in abrasiveness.纤维可占材料体积的三分之一以极大改善材料的强度和硬度。这种加强的负作用通常是抗冲击强度降低及磨损性增加。

The latter also has an effect on processing since the life of the mold cavity is typically reduced from about 1,000,000 parts for plain resin parts to about 300,000 for glass-filled parts.后者对加工过程也有影响，因为模具腔的寿命从典型的普通树脂零件大约1,000,000件减少到玻璃纤维填充树脂零件的约300,000件。

Perhaps the main weakness of injection-molded parts is the relatively low service temperatures to which they can be subjected.Thermoplastic components can only rarely be operated continuously above 250℃, with an absolute upper service temperature of about 400℃.注塑成型零件的主要缺点或许是它们能承受的工作温度相对较低。热塑性塑料零件只有很少能连续运行在250℃以上，其绝对最高工作温度约为400℃。

The temperature at which a thermoplastic can be operated under load can be defined qualitatively by the heat deflection temperature.This is the temperature at which a simply supported beam specimen of the material, with a centrally applied load, reaches a predefined deflection.热塑性塑料带载运行温度可从质量上定义为热偏差温度。这是中心承载的该材料简支梁达到预定偏差的温度。The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test values are only really useful for comparing different polymers.其温度值明显取决于试验条件和允许偏差，因此对比较不同的聚合物而言只有试验数据是真正有用的。

• Cycle of Operation 作业循环

The reciprocating screw injection molding machine is considered as consisting of two halves: a fixed injection side, and a movable clamp side.往复螺旋注塑成型机被认为由两部分组成：一个固定注塑端和一个活动夹具端。

The injection side contains the extruder that receives solid resin in pellet or granular form and converts it into a viscous liquid or melt that can be forced through the connecting nozzle, spine, and runners to the gates that lead into the mold cavities.注塑端包含压出机，它接受小球或粒状的固体树脂，然后将其转化为粘性液体或称为融化，再强迫其通过连接喷嘴、中心和浇道到闸道进入模具腔。

The mold is tightly clamped against injection pressure and is cooled well below the melt temperature of the thermoplastic.When the parts in the cavities have cooled sufficiently the mold halves are opened at the mold parting plane and the parts ejected by a knockout system drop into a receiving bin below.模具被紧紧地夹住以抵抗注塑压力，并在热塑性塑料的融化温度以下很好地冷却。当模腔内的零件充分冷却，剖分模在模具分模面处打开，推出系统将零件推出落入下面的接收容器内。

This summarizes the overall cycle, but leaves out much vital detail that is necessary for understanding the process.However, with this introduction, it is possible to understand the advantages and disadvantages of the process.这概述了整个循环，但省略了许多对理解此工艺所必需的很重要细节。然而通过本介绍，了解这种工艺的优缺点仍是可能的。

• Effects of Process Variables on Orientation

加工变量对方向性的影响

In injection molding, any variation in processing that keeps the molding resin hot throughout filling allows increased relaxation and, therefore, decreased orientation.Some of the steps that can be taken to reduce orientation are as follows.在注塑成型时，整个填料过程始终保持成型树脂高温的任何加工变化都会增加松弛作用而减少方向性。下面是可以用于减少方向性的若干措施。

• Faster injection(up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning;better flow to corners;and less

crystallinity all favor lower subsurface orientation.The primary effect is that the gate will freeze more quickly.At that point, orientation stops and relaxation starts.• 较快注塑(到点)：在填料过程中冷却较少，因此初始固化层较薄，由于剪应变稀少而粘性较低；能较好地流到角落；结晶度较小；所有这些促成表面下的方向性也较低。主要效果是闸道将较快固化。这样使得方向性停止产生而松弛作用开始增加。

• Higher melt and mold temperatures: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.• Reduced packing time and pressure: overpacking inhibits relaxation processes.• 较高的融化和成型温度：融化粘性较低，更容易填充，较大松弛作用促成方向性减少。• 减少挤压时间和压力：过度挤压会抑制松弛过程。

• Reduced gate size: larger gates take longer to freeze off and permit increased orientation.• 减小闸道尺寸：闸道越大则固化时间越长并会使方向性增加。

Excessively high injection speed can cause high surface orientation and increase susceptibility to stress cracking.For example, moldings that are to be electroplated, and will be subject to acid solutions during plating, must be made using very slow injection speeds to minimize surface orientation.过高的注塑速度会引起较高的表面方向性及增加应力破裂的敏感性。例如，要电镀的注塑件在电镀时会经受酸溶液，必须采用很低的注塑速度制造以使表面方向性最小化。

On the other hand, the transverse motion component of the melt front in most moldings can cause transverse subsurface orientation superimposed on the primary orientation, giving a desirable biaxial orientation effect.另一方面，大多数注塑件的融化前部横向运动部分能导致在主要方向性上有层理的表面下横向方向性，产生需要的双轴方向性效应。

Orientation can be seriously increased by obstructions to flow during filling of the cavity.Flow around an obstruction causes a decrease in melt front speed and leads to high local viscosity and reduced relaxation.This is also likely to occur near the end of the filling phase if gating is inadequate.在填充模腔时流动受到阻碍会极大地增加方向性。围绕障碍物流动使融化前部的速度下降并产生较高的局部粘性而减少松弛作用。如果闸道不适当，这也很可能发生在接近填充结束阶段。

The molder must recognize the dangers of excessive fill speed, insufficient injection pressure, excessive melt temperature, and inadequate packing.These dangers are weighed against the opposing effects on orientation discussed above.注塑工必须认识过快填充速度、不足注塑压力、过高融化温度和不充分挤压的危害性。这些危害性要与上述方向性的反向效应相权衡。

Thicker parts delay cooling and increase relaxation time and tend to result in lower orientation.Thicker parts also tend to warp less.Therefore, a minimum wall thickness can be established by experience for various shapes, materials, and process combinations.较厚零件会延迟冷却并且增加松弛时间，趋向于导致较低的方向性。较厚零件也有助于减少翘曲。因此，对各种形状、材料和工艺组合能通过经验来确定最小壁厚。

Lower molecular weight and broader molecular weight distribution in thermoplastics favor lower orientation and reduced internal stress in moldings.在热塑性塑料中较小的分子量以及较宽泛的分子量分布促成方向性减少同时降低注塑件中的内应力。The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation;that is, it decreases as the melt or mold temperatures and cavity pressure increases.Tensile strength and stiffness increase as skin thickness ratio increases.Microscopic examination thus provides another way of studying the process efficiently.外壳厚度比受加工变量影响的方式与方向性预测一样；也就是它能随融化或成型温度及模腔压力的增加而减少。拉伸强度和硬度随外壳厚度比增加而增加。因而显微镜检查提供了有效研究该工艺的另一方法。

• Advantages

优点

1.High production rates.For example, a CD disk can be produced with a 10~12s cycle in high melt flow index PC.1.高生产率：例如，一张CD盘在高融体流动指数生产控制中只需10~12s一个循环就能生产出来。2.Relatively low labor content.One operator can frequently take care of two or more machines, particularly the moldings are unloaded automatically onto conveyors.2.相对较少的工作内容：一个操作者经常可以照看两台以上机械，尤其是当成品能自动卸到输送机上时。3.Parts require little or no finishing.For example, flash can be minimized and molds can be arranged to automatically

separate runners and gates from the part itself.4.Very complex shapes can be formed.Advances in mold tooling are largely responsible.3.零件几乎不需要修整：例如，飞边可以最小化并且模具能被设计成自动将浇道和闸道从零件本身分离。4.非常复杂的形状也能成型：模具的进步很大程度上是可靠的。

5.Flexibility of design(finishes, colors, inserts, materials).More than one material can be molded through co-injection.Foam core materials with solid skins are efficiently produced.Thermosetting plastics and fiber-reinforced shapes are injection molded.5.设计的灵活性(光洁度、颜色、插入物、材料)：通过复合注塑可以成型多于一种材料。可以高效地生产带有固体外壳的泡沫型芯材料。热硬化性塑料和纤维加强形状都可以注塑成型。

6.Minimum scrap loss.Runners, gates, and scrap can usually be reground.Recycled thermoplastics can be injection molded.6.废料损失最小化：浇道、闸道和废料通常可以重新研磨。循环热塑性塑料可以注塑成型。

7.Close tolerances are obtainable.Modern microprocessor controls, fitted to precision molds, and elaborate hydraulics, facilitate tolerances in the 0.1% range on dimensions and weights(but not without a high level of operational skills in constant attendance).7.能得到接近的公差：现代微处理器控制、合适的精密模具和精心制作的液压设备使得尺寸和重量的公差保持在0.1% 的范围内(但不是没有在持续照看时的高水平操作技能)。

8.Makes best use of the unique attributes of polymers, such as flow ability, light weight, transparency, and corrosion resistance.This is evident from the number and variety of molded plastic products in everyday use.8.充分利用聚合物诸如流动能力、重量轻、透明和耐腐蚀等独特属性：从日常使用成型塑料产品的数量和种类就能明显看到。

• Disadvantages and Problems 缺点和问题

1.High investment in equipment and tools requires high production volumes.2.Lack of expertise and good preventive maintenance can cause high startup and running costs.1.较高的设备和模具投资需要较高生产量才合算。

2.缺少专门技术和良好的预防性维修会导致较高的启动和运行成本。

3.Quality is sometimes difficult to determine immediately.For example, post-mold warpage may render parts unusable because of dimensional changes that are not completed for weeks or months after molding.3.质量有时难以马上确定。例如，成型后的翘曲会导致零件不能用，因为在成型后几星期甚至几个月尺寸变化都不能完成。

4.Attention is required on many details requiring a wide variety of skills and cross-disciplinary knowledge.5.Part design sometimes is not well suited to efficient molding.4.对许多需要广泛多样性技能和交叉学科知识的细节必须加以注意。5.零件设计有时不能很好地适应有效率的成型。

6.Lead time for mold design, mold manufacture and debugging trials is sometimes very long.6.模具设计、模具制造和调试试验这些先导工作有时要花费很长时间。

第七单元

The importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.(1)In USA, more than $100 billions are spent annually on machining and related operations.机加工过程的重要性可通过日常生活使用的每件产品都直接或间接经历这一过程的事实来强调。(1)在美国，每年花在机加工及其相关作业上的费用都多于千亿美元。

(2)A large majority(above 80%)of all the machine tools used in the manufacturing industry have undergone metal cutting.(3)An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.(2)用于制造业的全部机床中的大多数(多于80%)都经历过金属切削。(3)有估计显示美国生产的所有金属中约10到15%转变成了切屑。

These facts show the importance of metal cutting in general manufacturing.It is therefore important to understand the metal cutting process in order to make the best use of it.这些事实说明了金属切削在常规制造中的重要性。因此了解金属切削过程以充分利用它是重要的。A number of attempts have been made in understanding the metal cutting process and using this knowledge to help improve manufacturing operations which involved metal cutting.在了解金属切削过程并运用这些知识帮助改善与金属切削有关的制造作业方面已经做了许多努力。A typical cutting tool in simplified form is shown in Fig.7.1.The important features to be observed are follows.典型切削刀具的简化形式如图7.1所示。要注意的重要特征如下。

1.Rake angle.It is the angle between the face of the tool called the rake face and the normal to the machining

direction.Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.1.前角：它是被称为前倾面的刀具面与垂直机加工方向的夹角。前角越大，则切削越好且切削力越小，增加前角可以减少刀具前倾面上产生的金属阻塞。

This reduces the strength of the tool tip as well as the heat dissipation through the tool.Thus, there is a maximum limit to the rake angle and this is generally of the order of 15°for high speed steel tools cutting mild steel.It is possible to have rake angles at zero or negative.但这会和减少通过刀具散发的热量一样减少刀尖强度。因此前角有一最大限制，用高速钢刀具切削低碳钢通常为15°。前角取零度或负值也是可能的。

2.Clearance angle.This is the angle between the machined surface and the underside of the tool called the flank face.The clearance angle is provided such that the tool will not rub the machined surface thus spoiling the surface and increasing the cutting forces.A very large clearance angle reduces the strength of the tool tip, and hence normally an angle of the order of 5~6°is used.2.后角：这是机加工面与被称为后侧面的刀具底面夹角。后角使刀具不产生会损坏机加工面的摩擦和增加切削力。很大的后角会削弱刀尖的强度，因此一般采用5~6°的后角。

The conditions which have an important influence on metal cutting are work material, cutting tool material, cutting tool geometry, cutting speed, feed rate, depth of cut and cutting fluid used.对金属切削有重要影响的条件有工件材料、刀具材料、刀具几何形状、切削速度、进给率、切削深度和所用的切削液。

The cutting speed, v, is the speed with which the cutting tool moves through the work material.This is generally expressed in metres per second(ms-1).切削速度v指切削刀具经过工件材料的移动速度。通常用米每秒(ms-1)表示。

Feed rate, f, may be defined as the small relative movement per cycle(per revolution or per stroke)of the cutting tool in a direction usually normal to the cutting speed direction.Depth of cut, d, is the normal distance between the unmachined surface and the machined surface.进给率f可定义为每循环(每转或每行程)切削刀具在通常为垂直于切削速度方向的次要相对运动。切削深度d是未加工面与已加工面之间的垂直距离。

• Chip Formation 切屑的形成

Metal cutting process is a very complex process.Fig.7.2 shows the basic material removal operation schematically.金属切削过程是一个很复杂的过程。图7.2用图的形式显示了基本材料去除作业。

metal.在刀具前倾面前的金属直接受到压缩，首先弹性变形然后塑性变形。考虑到最终形状中的材料是通过剪切从母体金属去除的，此区域传统上称为剪切区。

The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip.Then the deformed metal(called chip)flows over the tool(rake)face.金属的实际分离始于屈服或断裂(视切削条件而定)，从切削刀尖开始。然后变形金属(称为切屑)流过刀具(前倾)面。

If the friction between the tool rake face and the underside of the chip(deformed material)is considerable, then the chip gets further deformed, which is termed as secondary deformation.The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.如果刀具前倾面与切屑(变形金属)底面之间的摩擦相当大，那么切屑进一步变形，这也叫做二次变形。滑过刀具前倾面的切屑被提升离开刀具，切屑弯曲的结果被称为切屑卷。

Plastic deformation can be caused by yielding, in which case strained layers of material would get displaced over other layers along the slip-planes which coincide with the direction of maximum shear stress.屈服能导致塑性变形，在这种情况下材料变形层沿着与最大剪应力方向一致的滑移面被其它层所取代。A chip is variable both in size and shape in actual manufacturing practice.Study of chips is one of the most important things in metal cutting.As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.在实际加工过程中切屑的尺寸和形状都是变化的。对切屑的研究是金属切削最重要的事情之一。如同后面将要看到的那样，金属切削力学极大地依赖于所产生切屑的形状和尺寸。

Chip formation in metal cutting could be broadly categorised into three types:(Fig.7.3)(1)Discontinuous chip(2)Continuous chip(3)Continuous chip with BUE(Built up edge)金属切削中的切屑形成可以宽泛地分成三个类型(图7.3)：(1)间断切屑(2)连续切屑

(3)带切屑瘤的连续切屑

Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other.Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.间断切屑：分段的切屑分散成小碎片，既可能相互附着也可能不相互附着。在靠近切削面处发生金属的剧烈变形，导致在运动刀具前方金属层产生裂缝。

Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation.With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.最后，横过切屑的剪切应力与材料的剪切强度相等，造成断裂和分离。生成这类切屑时，切屑沿刀具面几乎没有相对运动，见图7.3a。

Continuous chip.The continuous chip is characterized by a general flow of the separated metal along the tool face.There may be some cracking of the chip, but in this case it usually does not extend far enough to cause fracture.连续切屑：连续的切屑一般具有分离金属沿刀具面流动的特征。切屑可能有一些破裂，但在这种情况下切屑通常不会延长到足以引起断裂。

This chip is formed at the higher cutting speeds when machining ductile materials.There is little tendency for the material to adhere to the tool.The continuous chip usually shows a good cutting ratio and tends to produce the optimum surface finish, but it may become an operating hazard, Fig.7.3b.这种切屑形成于用较高切削速度机加工有延展性的材料时。材料几乎没有粘附刀具的倾向。连续切屑通常具有良好的切削率和趋向于产生最适宜的表面光洁度，但可能成为操作的危险之源，见图7.3b。

Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.实际上，对显微照片的分析显示这种切屑瘤受到静摩擦力抑制直至它变得大到作用在它上面的外力使其移动，一些留在机加工表面上而另一些延伸到切屑的背面，见图7.3c。

• Shear Zone

剪切区

There are basically two schools of thought in the analysis of the metal removal process.One school of thought is that the deformation zone is very thin and planar as shown in Fig.7.4a.The other school thinks that the actual deformation zone is a thick one with a fan shape as shown in Fig.7.4b.在对金属去除过程的分析中主要存在两种思想学派。一种思想学派认为变形区如图7.4a所示那样非常薄而平坦。另一学派则认为真实变形区象图7.4b所示那样为一厚的带有扇形的区域。

Though the first model(Fig.7.4a)is convenient from the point of analysis, physically it is impossible to exist.This is because for the transition from undeformed material to deform to take place along a thin plane, the acceleration across the plane has to be infinity.虽然第一种模型(图7.4a)从分析的角度看是方便的，但实际上是不可能存在的。这是由于未变形的材料沿着剪切面发生变形，而且越过剪切面的加速度无穷大。

第四篇：机械工程英语第二版翻译HT-12-14（范文）

第十二单元钻削和钻头

Drillingsurfaces.空心钻用于扩大已有的孔而不是打孔。这类钻头具有较大生产率、高加工精度和优良钻削表面质量的特性。

Gun drills.-to the tip of the drill.钻削作业既能采用手钻也能采用钻床来实现。钻床在尺寸和结构上虽有差别，然而始终都是切削刀具围绕自身轴线旋转、工件稳固定位的形式。这正好与在车床上钻孔相反。Cutting-, which can be straight or helical.用于钻削作业的切削刀具

在钻削作业中，要用到被称为钻头的圆柱形回转端切削刀具。钻头可以有一条或多条直的或是螺旋状的切削刃以及相应的出屑槽。

The functionfor transmitting rotation.锥形钻柄通过楔入动作安装在主轴的锥形轴孔中，钻柄上还有柄舌插入主轴轴孔中的插槽，从而作为传递转动的可靠方法。

On the other hand, straight-shank-shank drills.另一方面，直柄钻头用钻头卡盘夹住，接下来钻头卡盘则象锥形钻柄钻头一样安装在主轴轴孔内。

As can-while it is in operation.如图12.1所示，两条切削刃就是钻唇，通过凿子状边缘的楔形体连在一起。麻花钻还有两条导向边，用于作业中钻头的正确导向和定位。

The toolin.(i.e., 0.25 up to 80 mm).虽然也有硬质合金刀尖的钻头，麻花钻一般用高速钢制成。工业实际中使用的麻花钻尺寸范围为0.01到3.25英寸(即0.25到80毫米)。

Core drills.A core-the accuracy.空心钻：空心钻包括斜面、钻头体、钻颈和钻柄，如图12.2所示。这类钻头可以有三条或四条出屑槽及相同数量的保证良好导向的导向边，这样使得加工有高精深孔钻：深孔钻用于钻深孔。所有深孔钻都是直出屑槽的，并且均为单切削刃。钻头体中有个孔作为导管在相当大的压力下将冷却液传送到钻头顶端。There are t-drilling operation.深孔钻有两种类型，即用于钻盲孔的中心切削深孔钻和套孔钻。后者在其中心有一圆柱形沟槽，这样能生成整体芯在钻孔作业过程中引导钻头。

Spade drills.-easy to grind.扁平钻：扁平钻用于钻削3.5英寸(90毫米)或更大的大孔。其设计使得钻头成本明显节省、重量切实减轻，重量轻又使操作更方便。此外这种钻头容易磨利。

• Milling and Milling Cutter

铣削和铣刀

Milling-milling cutter.铣削是采用被称为铣刀的多刃旋转刀具完成的机加工作业。

In this process,-gear-cutting operation.在此工艺中，金属去除是通过铣刀的旋转运动和工件的直线运动的组合实现的。铣削作业既可用于生成平面、轮廓面和螺旋面，也可用于切削螺纹和齿轮。Each of-rake and relief angles.在铣刀切削工件金属时，铣刀的每条切削刃都象一单独的单刃刀具一样作用。所以每条切削刃都适当的前后角。

Since only-than those for turning or drilling.由于同一时间只有部分切削刃切削工件，因此可以在对刀具寿命没有不利影响的情况下承担重型切削。事实上，铣削允许的切削速度和进给比车削或钻削高三到四倍。Moreover,-by turning, shaping, or drilling.此外，由铣削加工的表面质量通常优于车削、刨削或钻削加工的表面质量。

A wide variety-of a machining workshop.工业上可采用的铣刀类型众多。连同铣床是极通用机床的事实，使得铣床成为机加工车间的支柱。As far as-he following two methods.至于涉及到铣刀转动的方向和工件的进给，铣削可以通过下列两种方法之一进行。

Up milling--cutting edges.逆铣(传统铣削)：在逆铣中，工件逆着铣刀转动的方向进给，如图12.3a所示。就像在此图中能看到的那样，切削深度(及作为结果的载荷)随着切削刃持续进入切削而逐渐增加。

Therefore,forces act downward.这会导致一种冲击，或突然加载。因此，这种方法只有当铣床在进给螺栓上配备间隙消除器时才采用。这种方法的优点包括机加工表面质量较高和工件由于切削力向下作用而较容易夹紧。

Types ofsurfaces.平面铣刀：平面铣刀是一种盘状切削刀具，它可以具有直齿或螺旋齿，如图12.4a所示。这类铣刀总是安装在卧式铣床上，用于机加工平面。

Face-cutter of this type.端面铣刀：端面铣刀也可用于机加工平面。它用螺栓固定在短刀杆的端部，而短刀杆则依次安装于立式铣床上。图12.4b显示了这类铣刀。

Plain-a very thin plain milling cutter.平面金属开槽锯刃铣刀：图12.4c显示了一种平面金属开槽锯刃铣刀。可以看到它其实是一种很薄的平面铣刀。

Side milling-can be straight or helical.侧铣刀：侧铣刀用于切削狭槽、凹槽和花键槽。正如图12.4d所示，它与平面铣刀十分相似，差别在于此类铣刀齿在侧面。象平面铣刀的情况一样，切削齿既可以是直的也可以是螺旋的。

Angle milling-this type.倾斜铣刀：倾斜铣刀用于切削燕尾槽、棘轮之类的。图12.4e显示了这类铣刀。

T-slot cutter.-milling T-slots.T型槽铣刀：如图12.4f所示，T型槽铣刀包括了一个平面铣刀和一根垂直于它的整体轴。正像其名字所表明的，这类铣刀用于铣削T型槽。

End mill--straight or helical.端面铣刀：端面铣刀在切削狭槽、凹槽、长凹槽、花键槽、凹状工件之类时均能发现其普遍应用。图12.4g为端面铣刀。它总是安装在立式铣床上，并具有两到四条既可是直的也可是螺旋的长凹槽。

Form millingspeeds are required.对大规模生产而言，因为其需要重型切削和/或高切削速度，铣刀顶端常装有烧结碳化物或有色金属碳合金作为切削齿。

第十四单元

Dimensioning 标注尺寸

The design-proper materials.机械设计除了计算载荷和应力、选择合适的材料外，还包括许多其它因素。

Before-all phases of production drawings.在建造或制造开始前，完成装配图和零件图以把必要信息传达给车间工人是必须的。在送往车间前设计者常常被召集来检查图纸。而在精通生产图纸的所有情况之前，需要有许多经验并熟悉制造工艺。

Drawings should-ne interpretation.图纸必须仔细检查其尺寸是否按生产部门最方便易懂的方式标注。很明显图纸应该只有唯一的解释。In particular,-for its mastery.尤其是不能要求车间工人在生产机械安排前进行三角或其它复杂的计算。

尺寸标注是一项复杂的工作，要掌握它需要有丰富的经验。

Tolerances-given dimension.由于要把零件加工到正好为给定尺寸是不可能的，因此图纸的尺寸必须加上公差以限制其可允许的变化。Although-or functional considerations permit.虽然较小公差能得到较高加工质量和较好操作机构，但随着公差的减小制造成本会迅速增加，如图14.1的典型曲线所示。因此公差被定为从操作或功能考虑允许的最大值是重要的。

Tolerances-each way from this dimension.公差既可以是单向的也可以是双向的。单向标注有一公差为零，所有变化都由另一公差给定。而双向标注则采用一平均尺寸，它将公差带中点从该尺寸双向扩展为相等的正负变化范围。

The development-ssembly with the mating parts.大规模低成本制造生产工艺的发展很大程度取决于组成零件的互换性。因此设计者必须确定单个零件的合适公差以及配合零件装配允许的正确间隙或过盈量。The manner of placing--such dimensions.在图纸上标注公差的方法相当程度上依赖于产品的性质或制造工艺的类型。如果尺寸公差没有特别注明，图纸应该包含一个给出这些尺寸公差值的普遍适用注释。However, some-single interpretation.然而有些公司不采用普遍适用注释，假定每个尺寸是单独被考虑的，可能会规定出比注释中要求的更宽的公差。在任何情况下图纸不模棱两可并只服从于单一的解释是十分重要的。

• Dimension and Tolerance 尺寸和公差

In dimensioninggeneral tolerances.偶尔也可能为了检查而必须给出供参考的辅助尺寸。在这种情况下，尺寸应该用括号括起来，以便参考。这样的尺寸不受通用公差控制。

Dimensions-other dimensions.影响零件功能的尺寸总是应该标注的而不要留作其它尺寸的和或差。

一根轴可能的名义尺寸为2.5in.(63.5mm)，但由于实际原因不用大成本是不能在制造中保持这个数字的，因此要增加确定的公差。如果允许有±0.003in.(±0.08mm)的变化，则此尺寸可表达为2.500±0.003(63.5±0.08mm)。Dimensions given closeconvenient to manufacture.图纸必须按方便制造零件的方式将设计者的要求真实和完整地表达出来。

Every dimension-possible, appear on the same view.对每一描述产品所需的尺寸都只须标注一次而不必在不同的视图中重复。有关同一特性的尺寸，诸如孔的位置和If thisinterchangeability.除非另行说明，所有尺寸都必须受图上的通用公差控制。一般这样的公差受到尺寸量值的控制。在影响功能或互换性的尺寸上必须标注专门的公差。A systemtolerance grade.公差是基本尺寸的函数并通过一个被称为等级的数字符号标明—即公差等级。

The position-of 45 mm might be 45H8/g7.公差相对于零线的位置同样为基本尺寸的函数通过一个或两个字母符号表达，大写字母表示孔而小写字母表示轴。这样基本尺寸为45毫米的一个孔和轴配合规格可能是45H8/g7。

Twenty standard grades-400~500 mm).ISO规定了二十种标准的公差等级，称之为IT01，IT0，IT1~18，给在直至500毫米强行分段(例如0~3，3~6，6~10,......, 400~500毫米)中的公称直径提供具体数值。

The value of-microns and D in millimeters.对5～16级而言，公差单位i的值可用下式计算这里i的单位是微米，而D的单位是毫米。

Standard shaft--of rather complex tables.标准的轴和孔偏差同样都由若干公式提供；然而对实际应用，公差和偏差都在三张相当复杂的表格中规定了。

Additional tables-and Horology”.对基本尺寸大于500毫米和在“一般用途”和“精密机械和钟表”两个类别中的“常用的轴和孔”而言，由附加的表格给出数值。

第五篇：机械工程英语第二版翻译

Unit1 Types of Materials

材料的类型

Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。

Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.工程材料还能进一步细分为：①金属材料②陶瓷材料③复合材料 ④聚合材料，等等。Metals and Metal Alloys 金属和金属合金

What are some important properties of metals?

Density is defined as a material’s mass divided by its volume.Most metals have relatively high densities, especially compared to polymers.金属有哪些重要特性？

The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires.金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。

Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性

高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和抗腐蚀性是陶瓷和玻璃的一些有用特性。Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.许多陶瓷都是电和热的良绝缘体。某些陶瓷还具有一些特殊性能：有些是磁性材料，有些是压电材料，还有些特殊陶瓷在极低温度下是超导体。陶瓷和玻璃都有一个主要的缺点：它们容易破碎。

Ceramics are not typically formed from the melt.This is because most ceramics will crack extensively(i.e.form a powder)upon cooling from the liquid state.陶瓷一般不是由熔化形成的。因为大多数陶瓷在从液态冷却时将会完全破碎(即形成粉末)。Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics.Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生产的简单有效的—诸如浇铸和吹制这些涉及熔化的技术都不能用于由晶体物组成的陶瓷的生产。作为替代，一般采用“烧结”或“焙烧”工艺。

An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光导纤维有三层：核心由高折射指数高纯光传输玻璃制成，中间层为低折射指数玻璃，是保护核心玻璃表面不被擦伤和完整性不被破坏的所谓覆层，外层是聚合物护套，用于保护光导纤维不受损。In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.为了使核心玻璃有比覆层大的折射指数，在其中掺入微小的、可控数量的能减缓光速而不会吸收光线的杂质或搀杂剂。

Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle.由于核心玻璃的折射指数比覆层大，只要在全内反射过程中光线照射核心/覆层分界面的角度比临界角大，在核心玻璃中传送的光线将仍保留在核心玻璃中。The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全内反射现象与核心玻璃的高纯度一样，使光线几乎无强度损耗传递长距离成为可能。Composites

复合材料

Composites are formed from two or more types of materials.Examples include polymer/ceramic and metal/ceramic composites.Composites are used because overall properties of the composites are superior to those of the individual components.复合材料由两种或更多材料构成。例子有聚合物/陶瓷和金属/陶瓷复合材料。之所以使用复合材料是因为其全面性能优于组成部分单独的性能。

复合材料有两种：纤维加强型复合材料和微粒加强型复合材料。Fiber-reinforced Composites

Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers.Fibers increase the modulus of the matrix material.纤维加强型复合材料

加强纤维可以是金属、陶瓷、玻璃或是已变成石墨的被称为碳纤维的聚合物。纤维能加强基材的模量。

The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿着纤维长度有很强结合力的共价结合在这个方向上给予复合材料很高的模量，因为要损坏或拉伸纤维就必须破坏或移除这种结合。

Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as

aluminum, and amorphous materials，including polymers and carbon black.微粒加强型复合材料

用于加强的微粒包含了陶瓷和玻璃之类的矿物微粒，铝之类的金属微粒以及包括聚合物和碳黑的非结晶质微粒。

聚合材料

Size.Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性

尺寸：单个聚合物分子一般分子量为10,000到1,000,000g/mol之间，具体取决于聚合物的结构—这可以比2,000个重复单元还多。

Interchain interactions.The polymer chains can be free to slide past one another(thermo-plastic)or they can be connected to each other with crosslinks(thermoset or elastomer).Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子链间的相互作用：聚合物的原子链可以自由地彼此滑动(热可塑性)或通过交键互相连接(热固性或弹性)。热可塑性材料可以重新形成和循环使用，而热固性与弹性材料则是不能再使用的。

Unit2

If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力集中于一般所说的钢上，经常要用到简化铁碳状态图。

The key transition described in this diagram is the decomposition of single-phase austenite(γ)to the two-phase ferrite plus carbide structure as temperature drops.在此图中描述的关键转变是单相奥氏体(γ)随着温度下降分解成两相铁素体加渗碳体组织结构。Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制这一由于奥氏体和铁素体的碳溶解性完全不同而产生的反应，使得通过热处理能获得很大范围的特性。

To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in Fig.2.1.At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron.When the steel cools to 727℃(1341℉), several changes occur simultaneously.为了理解这些过程，考虑含碳量为0.77%的共析钢，沿着图2.1的x-x’线慢慢冷却。在较高温度时，只存在奥氏体，0.77%的碳溶解在铁里形成固溶体。当钢冷却到727℃(1341℉)时，将同时发生若干变化。

The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C.In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.被析出的碳与金属化合物Fe3C形成富碳的渗碳体。本质上，共析体的基本反应是奥氏体0.77%的碳→铁素体0.02%的碳+渗碳体6.67%的碳。

At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite.Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.在较高温度时，这种材料全部是奥氏体，但随着冷却就进入到铁素体和奥氏体稳定状态的区域。由截线及杠杆定律分析可知，低碳铁素体成核并长大，剩下含碳量高的奥氏体。

淬火

Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state.Pearlite responds best to heat-treating operations;and steel composed mostly of pearlite can be transformed into a hard steel.高于此点，由于超过共析点钢完全由珠光体和退火状态的渗碳体组成，硬度增加并不多。珠光体对热处理作业响应最好；基本由珠光体组成的钢能转化成硬质钢。

No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness.However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature.无论淬火介质怎么冷，如果在大工件中的热量不能比特定的临界速率更快散发，那它内部硬度就会受到明确限制。然而盐水或水淬火能够将被淬零件的表面迅速冷却至本身温度并将其保持或接近此温度。Under these circumstances there would always be some finite depth of surface hardening regardless of size.This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.在这种情况下不管零件尺寸如何，其表面总归有一定深度被硬化。但油淬情况就不是如此，因为油淬时在淬火临界阶段零件表面的温度可能仍然很高。Tempering

回火

快速淬火硬化的钢是硬而易碎的，不适合大多数场合使用。通过回火，硬度和脆性可以降低到使用条件所需要的程度。

In the process of tempering, some consideration should be given to time as well as to temperature.Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.在回火过程中，不但要考虑温度而且要考虑时间。虽然大多数软化作用发生在达到所需温度后的最初几分钟，但如果此温度维持一段延长时间，仍会有些额外的硬度下降。

Annealing

退火

The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.退火的主要目的是使坚硬的钢软化以便机加工或冷作。

The process of normalizing consists of heating the steel about 50℉ to 100℉

(10℃~40℃)above the upper critical range and cooling in still air to room temperature.正火处理包括先将钢加热到高于上临界区50℉到100℉(10℃~40℃)然后在静止的空气中冷却到室温。

This process is principally used with low-and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties.Most commercial steels are normalized after being rolled or cast.退火主要用于低碳钢、中碳钢及合金钢，使晶粒结构更均匀、释放内应力或获得所需的物理特性。大多数商业钢材在轧制或铸造后都要退火。

The oldest known method of producing a hard surface on steel is case hardening or carburizing.Iron at temperatures close to and above its critical temperature has an affinity for carbon.渗碳

最早的硬化钢表面的方法是表面淬火或渗碳。铁在靠近并高于其临界温度时对碳具有亲合力。The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel.The carbon is gradually diffused to the interior of the part.The depth of the case depends on the time and temperature of the treatment.碳被吸收进金属与铁形成固溶体使外表面转变成高碳钢。碳逐渐扩散到零件内部。渗碳层的深度取决于热处理的时间和温度。

Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共渗

碳氮共渗，有时也称为干法氰化或渗碳氮化，是一种表面硬化工艺。通过把钢放在高于临界温度的气体中，让它吸收碳和氮。

Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化

氰化，有时称为液体碳氮共渗，也是一种结合了吸收碳和氮来获得表面硬度的工艺，它主要用于不适合通常热处理的低碳钢。

Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents.渗氮

渗氮有些类似普通表面硬化，但它采用不同的材料和处理方法来产生坚硬表面成分。

Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is little tendency to warp, develop cracks, or change condition in any way.The surface effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.值得庆幸的是由于渗氮处理一点都不影响内部结构和性能，也无需淬火，所以几乎没有任何产生翘曲、裂缝及变化条件的趋势。这种表面能有效地抵御水、盐雾、碱、原油和天然气的腐蚀反应。

Unit3

砂型铸造

In general, typical stages of sand casting operation include(as shown in Fig.3.2): 1.Patterns are made.These will be the shape used to form the cavity in the sand.一般而言，砂型铸造作业的典型阶段包括(如图3.2所示)： 1.制作型模。做成用于在型砂中形成型腔的形状。

4.Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed.A compaction stage is typically used to ensure good coverage and solid molds.4.型砂在型模周围成形，并根据需要安放闸道、浇道、冒口、排放口和浇注杯等。通常要采取压紧步骤来保证良好的覆盖和坚固的铸型。

9.随着熔化金属的冷却(几分钟到几天)，金属收缩体积减小。在此期间熔化金属可能从冒口回流供给零件以保持其形状不变。

11.Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal properties.At this point the sand is simply broken up, and the part removed.At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.11.一旦零件在共析点以下完全凝固，可以不考虑金属的最后性能而将其取出。这时可以简单地打碎砂型并取出零件，但零件表面会有大量型砂粘附着，内部还有实心的砂芯。

14.通过机加工将零件切削到最终形状。可能还要用清洗作业去除氧化物等。Investment casting熔模铸造

After this, the entire pattern is placed in an oven and the wax is melted away.This leads to a mold that can be filled with the molten metal.Because the mold is formed around a one-piece pattern(which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.完成后把整个型模放在烤箱里融化石蜡。这样就做成了能填充熔化金属的铸型。由于这种铸型是环绕整块型模形成的(无需像传统的砂型铸造工艺那样拔模)，能制作十分复杂的零件和浮雕。

Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions.Castings can weigh from a few grams to 35kg(0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb).Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.)for alloys that can be cast easily.一般公差可能为长度的0.5%，小尺寸可能低到0.15%。虽然通常尺寸的铸件重量范围为200g到约8kg(7oz到15lb)，但实际可从几克到35kg(0.1oz to 80lb)。对容易铸造的合金而言，通常壁厚约为1mm到0.5mm(0.040~ 0.020 in.)。

Semi-centrifugal casting.The molds used can be permanent or expendable, can be stacked as necessary.The rotational speeds are lower than those used in centrifugal casting.半离心铸造：型模可以是永久性的或是消耗性的，可根据需要叠加。它的旋转速度比离心铸造低。The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away.This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.零件的中心轴附近存在缺陷和孔隙，因此仅适用于能将这些机加工去除的零件。这种工艺被用于制造车轮、管嘴及类似的随后可用机加工去除中心轴部分的零件。

Full-mold casting is a technique similar to investment casting, but instead of wax as the expendable material, polystyrene foam is used as the pattern.The foam pattern is coated with a refractory material.The pattern is encased in a one-piece sand mold.As the metal is poured, the foam vaporizes, and the metal takes its place.实型铸造是与熔模铸造类似的技术，但它用做型模的消耗材料是聚苯乙烯泡沫而不是石蜡。泡沫型模用难熔材料覆盖。型模装入整体砂模中。当金属浇入时，泡沫材料蒸发，金属取代其位置。This can make complex shaped castings without any draft or flash.However, the pattern cost can be high due to the expendable nature of the pattern.Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions.Surface finish can be held from 2.5μm to 25μm(0.1μin.to 1.0μin.)rms(root-mean-square).它能制造没有拔模斜度和缝脊的复杂形状铸件。然而由于型模的消耗特性，型模成本可能较高。最小壁厚为2.5mm，公差能保持在尺寸的0.3% 之内。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之间。

Unit4 Introduction

引言

A distinction may be made between open-die forging, usually in the form of hammer forging, and closed-die forging.In hammer forging, the component is shaped by hammer blows aided by relatively simple tools.These may include open dies i.e., dies that do not completely enclose the metal to be shaped.锤锻中常用的开式模锻与闭式模锻是有区别的。在锤锻中零件通过锤击辅之以相对简单的工具成型。其中包括开式锻模，就是不完全封闭被成型金属的模具。

More important is closed-die forging, very widely used for mass production in industry, in which the metal is shaped by pressing between a pair of forging dies.The upper die is usually attached to the ram of a forging press or a forging hammer, while the lower die is stationary.更重要的是闭式模锻，在工业上广泛用于规模生产。闭式模锻中金属在一对锻模之间挤压成型。顶模通常放在锻压机的撞头或锻锤上，而底模则是固定的。

A piece of hot metal sufficient to slightly overfill the die shape is placed in the bottom die, and the top die is forced against it, so that the metal takes the internal shape of the die.将一块大小足以充填模腔并能稍有溢出的加热金属放入底模，并将顶模加压合拢，这块金属便获得该模腔的形状。Closed-die forging is used for the rapid production of large numbers of fairly small parts and also for very large components.For the latter, e.g., modern jet-aircraft components, giant hydraulically operated presses are used, which can develop forces of 50,000 tons and more.闭式模锻用于相当小的零件大批量快速生产，也可用于很大的零件。对后者而言，例如现代喷气飞机零件，使用能产生50,000吨以上压力的巨型液力锻压机。

Forging refines the grain structure and improves physical properties of the metal.With proper design, the grain flow can be oriented in the direction of principal stresses encountered in actual use.铸造细化金属的晶粒组织、改善其物理性能。通过适当的设计，可以使晶粒流动方向与实际使用时的主应力方向一致。

Forgings are consistent from piece to piece, without any of the porosity, voids, inclusions and other defects.Thus, finishing operations such as machining

Forgings yield parts that have high strength to weight ratio, thus are often used in the design of aircraft frame members.A forged metal can result in the following:

锻造生产的零件具有较高的强度重量比，所以常被用在飞机结构零件的设计中。

锻造金属可以导致下列结果：

Increase length, decrease cross-section, called drawing out the metal.Decrease length, increase cross-section, called upsetting the metal.Change length, change cross-section, by squeezing in closed impression dies.This results in favorable grain flow for strong parts.●增加长度、减小横截面，称为延伸金属。●减小长度、增加横截面，称为镦粗金属。●通过用封闭锻模挤压，改变长度和横截面。

这导致有利的晶粒流使零件坚固。Common Forging Processes常用的锻造工艺

The metal can be forged hot(above recrystallization temperatures)or cold.金属既可热锻(高于再结晶温度)也可冷锻。

Open die forgings/Hand forgings.Open die forgings or hand forgings are made with repeated blows in an open die, where the operator manipulates the workpiece in the die.The finished product is a rough approximation of the die.This is what a traditional blacksmith does, and is an old manufacturing process.开式模锻/手工锻：开式模锻或手工锻就是操作者操纵工件在开式锻模中反复击打。完成的产品是锻模的粗糙近似物。这就是传统铁匠干的活，是较古老的制造工艺。

Parting surface should be along a single plane if possible, else following the contour of the part.The parting surface should be through the center of the part, not near the upper or lower edges.如果可能分模面应沿着单一平面，否则就顺着零件轮廓方向。分模面应经过零件中心，而不要靠近上下边缘。

As in most forming processes, use of undercuts should be avoided as these will make the removal of the part difficult, if not impossible.如同大多数成型工艺，如果不是非用不可，尽量避免采用凹槽，因为凹槽会使零件难以取出。

Generous fillets and radius should be provided to aid in material flow during the forging process.Sharp corners are stress-risers in the forgings, as well as make the dies weak in service.Ribs should not be high or narrow;this makes it difficult for the material to flow.应提供尽可能大的倒角和半径以帮助材料在锻造过程中流动。锐角会增加锻件中的应力，同时在使用时削弱锻模。

加劲肋不要过高、过窄，因为这会造成材料流动困难。Tolerances

公差

Dimension tolerances are usually positive and are approximately 0.3% of the dimension, rounded off to the next higher 0.5mm(0.020in.).尺寸公差通常为正，大约取为该尺寸的0.3%，并圆整到较大的0.5mm(0.020in.)。

Die wear tolerances are lateral tolerances(parallel to the parting plane)and are roughly +0.2% for copper alloys to +0.5% for aluminum and steel.锻模磨损公差为侧向公差(平行于分模面)，对铜合金大约为+0.2%，对铝和钢大约为+0.5%。

Die closure tolerances are in the direction of opening and closing, and range from 1mm(0.040in.)for small forgings, die projection area＜150cm2(23in.2), to 6.25mm(0.25in.)for large forgings, die projection area＞6,500cm2(100in.2).锻模的闭合公差处于开闭的方向上，范围从对较小锻件[其投影面积＜150cm2(23in.2)]取为1mm(0.040in.)，到较大锻件[其投影面积＞6,500cm2(100in.2)]取为6.25mm(0.25in.)。

Die match tolerances are to allow for shift in the upper die with respect to the lower die.锻模的配合公差是为了允许上模能根据下模替换。

Unit5

材料

The majority of the structural components produced by fixed die pressing are iron-based.The powders are elemental, pre-alloyed, or partially alloyed.大多数用固定模压制的结构件都是铁基的。粉末可以是单一元素、预先合金或部分合金。Elemental powders, such as iron and copper, are easy to compress to relatively high densities, produce pressed compacts with adequate strength for handling during sintering, but do not produce very high strength sintered parts.诸如铁、铜之类的单一元素粉末较容易被压得相对密度较高、生产具备足够强度的压制物供烧结处理，但是无法制造出很高强度的烧结零件。

Pre-alloyed powders are harder, less

A similar technique is to “glue” the small percentage of alloying element onto the iron powder.This “glueing” technique is successfully used to introduce carbon into the blends, a technique which prevents carbon segregation and dusting, producing so-called “clean” powders.另一种类似的技术是把小百分比的合金元素“粘合”到铁微粒上。这种“粘合”技术已成功用于将碳引入结合物，一种防止碳分离并起尘的技术，生产所谓的“清洁”粉末。Powder Consolidation粉末合成

还好有多种合成技术可供选择。Cold Uniaxial Pressing

Elemental metal, or an atomized pre-alloyed powder is mixed with a lubricant, typically lithium stearate(0.75 wt.%), and pressed at pressures of say, 600MPa(87,000lb/in.2)in metal dies.冷单向挤压

One disadvantage of this technique is the differences in pressed density that can occur in different parts of the component due to particle/particle and die wall/particle frictional effects.Typical as-pressed densities for soft iron components would be 7.0g/cc, i.e.about 90% of theoretical density.这种技术的缺点之一是由于微粒/微粒和模壁/微粒间的摩擦效应，零件不同部位的压实密度存在差异。典型的软铁零件压制密度为7.0g/cc，即大约是理论密度的90%。

Metal powders are contained in an enclosure e.g.a rubber membrane or a metallic can that is subjected to isostatic, which is uniform in all directions, external pressure.As the pressure is isostatic the as-pressed component is of uniform density.冷均衡挤压

金属粉末装入均衡受压的橡胶膜或金属罐内，其所受外压力在各个方向都是均匀的。由于压力是均衡的，所以压制零件密度是均匀的。

Normally this technique is only used for semi-fabricated products such as bars, billets, sheet, and roughly shaped components, all of which require considerable secondary operations to produce the final, accurately dimensioned component.通常这种技术只用于制作诸如棒料、坯段、薄板及粗糙成型零件之类的半成品，所有这些都需要大量进一步加工才能生产出最终尺寸精确的零件。

烧结就是通过把粉末压制物加热使邻近的微粒熔合在一起的工艺，它能生成比粉末压制物机械强度更好的固体物。

The density of the component can also change during sintering, depending on the materials and the sintering temperature.These dimensional changes can be controlled by an understanding and control of the pressing and sintering parameters，根据材料和烧结温度的不同，零件的密度在烧结过程中也会改变。因为尺寸的变化可以通过了解并调节挤压及烧结参数进行控制，and components can be produced with dimensions that need little or no rectification to meet the dimensional tolerances.Note that in many cases all of the powder used is present in the finished product, scrap losses will only occur when secondary machining operations are necessary.所以零件尺寸几乎无需校正就能满足尺寸公差。可以看到在很多情况下所有使用的粉末都包含在制成品中，废料损失仅产生于需要辅助机加工时。Hot Isostatic Pressing

Powders are usually encapsulated in a metallic container but sometimes in glass.The container is evacuated, the powder out-gassed to avoid contamination of the materials by any residual gas during the consolidation stage and sealed-off.热均衡挤压

粉末通常封装在金属容器内有时也装在玻璃容器内。把容器抽真空，粉末抽气是为了防止材料在合成阶段和密封时被残留气体污染。

It is then heated and subjected to isostatic pressure sufficient to plastically deform both the container and the powder.再加热并施加均衡压力足以使容器和粉末都塑性变形。

As with cold isostatic pressing only semi-finished products are produced, either for subsequent working to smaller sizes, or for machining to finished dimensions.此工艺与采用冷均衡挤压一样只能生产半成品，可以通过后续加工至较小尺寸，也能用机加工到最终尺寸。

Hot Forging(Powder Forging)

Cold pressed and sintered components have the great advantage of being close to final shape(near-net shape), but are not fully dense.Where densification is essential to provide adequate mechanical properties, the technique of hot forging, or powder forging, can be used.热锻(粉末锻造)

冷挤压和烧结零件主要优点是接近最终形状(近似纯形)，但不是充分致密的。当为了提供足够的机械性能而致密化是必须时，可以采用热锻或粉末锻造技术。

Injection moulding is very widely used to produce precisely shaped plastic components in complex dies.As injection pressures are low it is possible to manufacture complex components, even some with internal screw threads, by the use of side cores and split tools.金属注塑成型(MIM)

注塑成型被很广泛地用于在复杂模具中生产形状精确的塑料零件。注塑压力较低使得制作复杂零件成为可能，通过采用侧面型芯和分离工具甚至可以带有内螺纹。

Shrinkage can be large, due to both the fine particle size of the powders and the substantial proportion of polymer binder used.由于所用粉末细小微粒的尺寸和聚合物粘合剂的真实比例，收缩可以比较大。Features

特征

For high tolerance parts, a sintering part is put back into a die and repressed.In genera this makes the part more accurate with a better surface finish.对较大公差的零件，烧结后可放回模具重新挤压。一般而言这会使零件更精确同时具有更好的表面光洁度。A part has many voids that can be impregnated.One method is to use an oil bath.Another method uses vacuum first, then impregnation.零件有许多可供填充的空间。一种方法是采用油浴。另一种方法是先抽真空然后再充满。

A part surface can be infiltrated with a low melting point metal to increase density, strength, hardness, ductility and impact resistance.Plating, heat treating and machining operations can also be used.零件表面能被低熔点金属渗透以增大密度、强度、硬度、延展性和抗冲击能力。仍然可以进行电镀、热处理和机加工作业。Advantages

优点

Good tolerances and surface finish Highly complex shapes made quickly Can produce porous parts and hard to manufacture materials(e.g.cemented oxides)良好的公差和表面光洁度高度复杂的形状能快速制作

能制作多孔零件和难以加工材料(如粘结氧化物)Pores in the metal can be filled with other materials/metals Surfaces can have high wear resistance Porosity can be controlled Low waste Automation is easy 金属中的气孔可用其它材料/金属填充表面能具有较高的耐磨性孔隙率可以控制较低损耗容易自动化

Physical properties can be controlled Variation from part to part is low Hard to machine metals can be used easily No molten metals 物理性能可以控制零件之间的变化较小难以机加工的金属能被容易使用无需熔化金属

No need for many/any finishing operations Permits high volume production of complex shapes Allows non-traditional alloy combinations Good control of final density 不需要很多/任何修整作业允许加工复杂形状的大体积产品允许非传统合金结合对最终密度能很好地控制 Disadvantages

缺点

Metal powders deteriorate quickly when stored improperly Fixed and setup costs are high Part size is limited by the press and compression of the powder used 如果存放不当金属粉末质量很快降低安装和调整的成本较高

零件尺寸受压力机和所用粉末压缩的限制

Sharp corners and varying thickness can be hard to produce Non-moldable features are impossible to produce 锐角和变厚度较难加工不适合模压的东西不可能生产

Unit6

If newer modifications, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase.如果考虑到新近的改进(例如反作用注塑成型)和采用塑料替代金属的高增长率，注塑成型在世界范围的工业重要性很可能将继续增加。

The machines and their products are ubiquitous and are synonymous with plastics for many people.这类机械和它们的产品普遍存在，对许多人来说与塑料是同义的。

A reciprocating screw injection molding machine combines the functions of an extruder and a compressive molding press.往复螺旋注射成型机把压出机和成型压力机的功能结合起来。

Injection molding is particularly worthy of intensive study because it combines many areas of interest extrusion, mold design, rheology, sophisticated hydraulic and electronic controls, robotic accessories, design of complex products, and, of course, the integration of materials science and process engineering.注塑成型对深入研究很有价值，因为它结合了许多重要领域，如挤压、模具设计、流变学、完备的液压和电子控制、机器人配件、复杂产品的设计，当然还有材料科学与加工工程的综合。

Injection Molding Materials注塑成型材料

Other polymers, such as a mixture of resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process.In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.其它聚合物，例如树脂和编织的或垫子形的玻璃纤维的混合物，由于它们的物理性质不适合使用此工艺。一般而言，能进入流动状态的聚合物都可以注塑成型。

This is because the long-chain molecules of the material always remain as separate entities and do not form chemical bonds to one another.An analogy car, be made to a block of ice that can be softened(i.e.turned back to liquid), poured into any shape cavity, and then cooled to become a solid again.这是由于这类材料的长链分子总是保持分离的实体并不相互形成化学连结。一辆由冰块制成的模拟汽车，可以融化(即转化为液态)，倒入任何形状的空腔，然后冷却重新变成固体。

In general, most of the thermoplastic materials offer high impact strength, corrosion resistance, and easy processing with good flow characteristics for molding complex designs.Thermoplastics are generally divided into two classes: namely crystalline and amorphous.一般而言，大多数热塑性材料具有较高的抗冲击强度、耐腐蚀性以及良好流动性使其容易加工而适于复杂成型设计。热塑性塑料通常分为两类：即结晶质的和非结晶质的。Crystalline polymers have an ordered molecular arrangement, with a sharp melting point.Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque.结晶质聚合物具有规则的分子排列及明显的熔点。由于规则的分子排列，结晶质聚合物能反射大多数特定光线并一般表现为不透明的。

The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement.This takes the form of short-chopped fibers, a few millimeters in length, which are randomly mixed with the thermoplastic resin.就本质而言，热塑性塑料的机械性能低于金属，但可以通过加入玻璃纤维强化予以增强来适应某些运用。常用几毫米长的短碎纤维随机地与热塑性树脂混合。

The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test values are only really useful for comparing different polymers.其温度值明显取决于试验条件和允许偏差，因此对比较不同的聚合物而言只有试验数据是真正有用的。Cycle of Operation作业循环

Effects of Process Variables on Orientation

加工变量对方向性的影响

Faster injection(up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning;better flow to corners;and less

crystallinity all favor lower subsurface orientation.The primary effect is that the gate will freeze more quickly.At that point, orientation stops and relaxation starts.较快注塑(到点)：在填料过程中冷却较少，因此初始固化层较薄，由于剪应变稀少而粘性较低；能较好地流到角落；结晶度较小；所有这些促成表面下的方向性也较低。主要效果是闸道将较快固化。这样使得方向性停止产生而松弛作用开始增加。

Higher melt and mold temperatures: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.Reduced packing time and pressure: overpacking inhibits relaxation processes.较高的融化和成型温度：融化粘性较低，更容易填充，较大松弛作用促成方向性减少。减少挤压时间和压力：过度挤压会抑制松弛过程。

Reduced gate size: larger gates take longer to freeze off and permit increased orientation.减小闸道尺寸：闸道越大则固化时间越长并会使方向性增加。

The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation;that is, it decreases as the melt or mold temperatures and cavity pressure increases.Tensile strength and stiffness increase as skin thickness ratio increases.Microscopic examination thus provides another way of studying the process efficiently.外壳厚度比受加工变量影响的方式与方向性预测一样；也就是它能随融化或成型温度及模腔压力的增加而减少。拉伸强度和硬度随外壳厚度比增加而增加。因而显微镜检查提供了有效研究该工艺的另一方法。

Advantages

优点

1.High production rates.For example, a CD disk can be produced with a 10~12s cycle in high melt flow index PC.1.高生产率：例如，一张CD盘在高融体流动指数生产控制中只需10~12s一个循环就能生产出来。

2.Relatively low labor content.One operator can frequently take care of two or more machines, particularly the moldings are unloaded automatically onto conveyors.2.相对较少的工作内容：一个操作者经常可以照看两台以上机械，尤其是当成品能自动卸到输送机上时。

3.Parts require little or no finishing.For example, flash can be minimized and molds can be arranged to automatically separate runners and gates from the part itself.4.Very complex shapes can be formed.Advances in mold tooling are largely responsible.3.零件几乎不需要修整：例如，飞边可以最小化并且模具能被设计成自动将浇道和闸道从零件本身分离。

4.非常复杂的形状也能成型：模具的进步很大程度上是可靠的。

Disadvantages and Problems缺点和问题

2.缺少专门技术和良好的预防性维修会导致较高的启动和运行成本。

5.零件设计有时不能很好地适应有效率的成型。

6.Lead time for mold design, mold manufacture and debugging trials is sometimes very long.6.模具设计、模具制造和调试试验这些先导工作有时要花费很长时间。

Unit7

(1)在美国，每年花在机加工及其相关作业上的费用都多于千亿美元。

(3)有估计显示美国生产的所有金属中约10到15%转变成了切屑。

A typical cutting tool in simplified form is shown in Fig.7.1.The important features to be observed are follows.典型切削刀具的简化形式如图7.1所示。要注意的重要特征如下。

1.Rake angle.It is the angle between the face of the tool called the rake face and the normal to the machining direction.Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.1.前角：它是被称为前倾面的刀具面与垂直机加工方向的夹角。前角越大，则切削越好且切削力越小，增加前角可以减少刀具前倾面上产生的金属阻塞。

切削深度d是未加工面与已加工面之间的垂直距离。Chip Formation 切屑的形成

The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically.This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent metal.在刀具前倾面前的金属直接受到压缩，首先弹性变形然后塑性变形。考虑到最终形状中的材料是通过剪切从母体金属去除的，此区域传统上称为剪切区。

A chip is variable both in size and shape in actual manufacturing practice.Study of chips is one of the most important things in metal cutting.As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.在实际加工过程中切屑的尺寸和形状都是变化的。对切屑的研究是金属切削最重要的事情之一。如同后面将要看到的那样，金属切削力学极大地依赖于所产生切屑的形状和尺寸。

Chip formation in metal cutting could be broadly categorised into three types:(Fig.7.3)

(1)Discontinuous chip

(2)Continuous chip

(3)Continuous chip with BUE(Built up edge)

金属切削中的切屑形成可以宽泛地分成三个类型(图7.3)：

(1)间断切屑

(2)连续切屑

(3)带切屑瘤的连续切屑

Continuous with a built-up edge.This chip shows the existence of a localized, highly deformed zone of material attached or “welded” on the tool face.带切屑瘤的连续切屑：这种切屑显示了粘合或“焊接”在刀具面上材料局部高度变形区的存在。Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.实际上，对显微照片的分析显示这种切屑瘤受到静摩擦力抑制直至它变得大到作用在它上面的外力使其移动，一些留在机加工表面上而另一些延伸到切屑的背面，见图7.3c。Shear Zone

剪切区

Similarly the stress gradient across the shear plane has to be very large to be practical.同样在实际运用中越过剪切面的应力梯度必须很大才行。

In the second model(Fig.7.4b)by making the shear zone over a region, the transitions in velocities and shear stresses could be realistically accounted for.在第二种模型(图7.4b)中让剪力区分布于一个范围，速度和剪应力的转变能说明得更符合实际。

The angle made by the shear plane with the cutting speed vector, Φ is a very important parameter in metal cutting.Higher the shear angle better is the cutting performance.From a view of the Fig.7.4a, it can be observed that a higher rake angles give rise to higher shear angles.由剪切面和切削速度矢量形成的角度Φ在金属切削中是一个十分重要的参数。剪切角越大，切削作业越好。从图7.4a观察，可以看到较大的前角能增大剪切角。Cutting Tool Materials切削刀具材料

Various cutting tool materials have been used in the industry for different applications.A number of developments have occurred in the current century.在工业中为了不同的应用可以使用各种各样的切削刀具材料。在最近的百年里产生了许多进展。A large variety of cutting tool materials has been developed to cater to the variety of materials used in these programmes.Before we discuss the properties of these materials, let us look at the important characteristics expected of a cutting tool material.多种切削刀具材料被开发出来以满足这些方案中使用材料的多样性。讨论这些材料性能之前，先看一下作为切削刀具材料应具备哪些重要特性。

1.Higher hardness than that of the workpiece material being machined, so that it can penetrate into the work material.2.Hot hardness, which is the ability of the material to retain its hardness at elevated temperatures in view of the high temperatures existing in the cutting zone.1.硬度要比被切削工件材料高，这样它才能进入工件材料。

2.热硬度，即材料由于存在于切削区的高温而升温时仍能保持其硬度的能力。

3.Wear resistance—The chip-tool and chip-work interfaces are exposed to such severe conditions that adhesive and abrasion wear is very common.The cutting tool material should therefore have high abrasion resistance to improve the effective life of the tool.3.耐磨性—切屑-刀具与切屑-工件的接触界面处于如此严酷的状态，粘附和磨损是很普遍的。因此切削刀具材料应具有高耐磨性以提高刀具的有效寿命。

4.Toughness—Even though the tool is hard, it should have enough toughness to withstand the impact loads that come in the beginning of cut or force fluctuations due to imperfections in the work material.This requirement is going to be more useful for the interrupted cutting, e.g.milling.4.韧性—虽然刀具是坚硬的，但也应有足够的韧性以经受住冲击载荷，这些载荷来自于切削的开始或由于工件材料的缺陷而产生的作用力波动。这个要求对如铣削之类的间断切削更有用。

5.Low friction—The coefficient of friction between the chip and tool should be low.This would allow for lower wear rates and better chip flow.5.低摩擦系数—切屑与刀具间的摩擦系数应当较低。这会使磨损率较小及切屑流动更好。

6.Thermal characteristics—Since a lot of heat is generated at the cutting zone, the tool material should have higher thermal conductivity to dissipate this heat in the shortest time, otherwise the tool temperature would become high, reducing its life.6.热特性—因为大量的热产生在切削区，刀具材料应当具有较高的热传导性以在最短的时间内散发热量，否则刀具温度会升高，寿命会减少。

All these characteristics may not be found in a single tool material.Improved tool materials have been giving a better cutting performance.所有这些特性不可能存在于单一刀具材料中。改进的刀具材料已经被赋予较好的切削性能。Surface Finish

表面光洁度

Machining operations are utilized in view of the better surface finish that could be achieved by it compared to other manufacturing operations.由于机加工能获得比其它制造作业更好的表面光洁度，所以机加工作业具有实用价值。

Thus it is important to know what would be the effective surface finish that can be achieved in a machining operation.The surface finish in a given machining operation is a result of two factors: 因而了解能在机加工作业中获得怎样的实际表面光洁度是重要的。给定机加工作业中的表面光洁度是两个因素共同作用的结果：

(1)the ideal surface finish, which is a result of the geometry of the manufacturing process which can be determined by considering the geometry of the machining operation, and(2)the natural component, which is a result of a number of uncontrollable factors in machining, which is difficult to predict.理想的表面光洁度，是通过考虑机加工作业的几何体系所决定的制造工艺几何学的结果，和自然要素，即在机加工中一些难以预测的不可控因素作用的结果。Ideal Surface Finish in Turning

The actual turning tool used would have a nose radius in place of the sharp tool point, which modifies the surface geometry as shown in Fig.7.5a.If the feed rate is very small, as is normal in finish turning, the surface is produced purely by the nose radius alone as shown in Fig.7.5.车削中的理想表面光洁度

实际使用的车削刀具有一个刀尖半径取代锋利刀尖，它将表面几何形状加工为如图7.5a所示。如果进给率很小，象精车中很正常的那样，工件表面则完全是由刀尖半径单独产生的，如图7.5所示。

For the case in Fig.7.5, the surface roughness value is to be

Ra=8f2/(18R√3)Where: Ra is the surface roughness value

R is the nose radius

f is the feed rate

对图7.5这种情况，表面粗糙度值为

Ra=8f2/(18R√3)式中：Ra是表面粗糙度值

R是刀尖半径

f是进给率

The above are essentially geometric factors and the values represent an ideal situation.The actual surface finish obtained depends to a great extent upon a number of factors such as:

上述基本为几何要素，其值代表了理想情况。而实际获得的表面光洁度很大程度上还取决于下列一些因素：

(1)the cutting process parameter, speed, feed and depth of cut(2)the geometry of the cutting tool(3)application of cutting fluid(4)work and tool material characteristics(5)rigidity of the machine tool and the consequent vibrations.(1)切削工艺参数、速度、进给和切削深度(2)切削刀具的几何形状(3)切削液的运用

(4)工件和刀具的材料特性

(5)机床的刚度及其伴随发生的振动

The major influence on surface finish is exerted by the feed rate and cutting speed.As the feed decreases, from the above equations, we can see that the roughness index decreases.对表面光洁度产生主要影响的是进给率和切削速度。从上述公式可以看到，随着进给的减少，粗糙度指标会降低。

Similarly as the cutting speed increases, we have better surface finish.Thus while making a choice of cutting process parameters for finish, it is desirable to have high cutting speed and small feed rates.同样随着切削速度的增大，能得到较好表面光洁度。因此在为光洁度而选择切削工艺参数时，采用较高的切削速度和较小的进给率是适当的。Cutting Fluids

切削液

The functions of cutting fluids(which are often erroneously called coolants)are: To cool the tool and workpiece To reduce the friction

切削液(经常误称为冷却液)的功能如下：冷却刀具和工件减少摩擦

To protect the work against rusting To improve the surface finish To prevent the formation of built-up edge To wash away the chips from the cutting zone 保护工件不生锈改善表面光洁度防止切屑瘤的形成从切削区冲掉切屑

However, the prime function of a cutting fluid in a metal cutting operation is to control the total heat.This can be done by dissipating the heat generated as well as reducing it.The mechanisms by which a cutting fluid performs these functions are: cooling action and lubricating action.然而，在金属切削作业中切削液的主要功能是控制总热量。这可通过既散发又减少所产生的热量来达到。切削液实现这些功能的机理是：冷却作用和润滑作用。

Cooling action.Originally it was assumed that cutting fluid improves the cutting performance by its cooling properties alone.That is why the name coolant was given to it.冷却作用：最初设想切削液仅仅是通过冷却特性来改善切削作业。这也是它曾被称为冷却液的原因。

Since most of the tool wear mechanisms are thermally activated, cooling the chip tool interface helps in retaining the original properties of the tool and hence prolongs its life.由于大多数刀具的磨损机理都是由热引起的，冷却切屑刀具接触界面有助于保持刀具的原有特性，从而延长其使用寿命。

However, a reduction in the temperature of the workpiece may under certain conditions increase the shear flow stress of the workpiece, thereby decreasing tool life.It has been shown through a number of investigations that cooling in fact is one of the major factors in improving the cutting performance.可是工件温度的降低在特定条件下会增加工件的剪切流动应力，从而降低刀具寿命。通过一些研究已经表明实际上冷却只是改善切削作业的主要因素之一。

Lubricating action.The best improvement in cutting performance can be achieved by the lubricating action since this reduces the heat generated, thus reducing the energy input to the metal cutting operation.润滑作用：切削作业的最大改善可通过润滑作用来达到，由于它减少了热量的产生因而减少了金属切削作业的能量输入。

However, if the cutting fluid is to be effective, it must reach the chip tool interface.But it is not easy to visualize how it is accomplished in the case of a continuous turning with a single point turning tool, specially when the chip-tool contact pressure is as high as 70 MPa.可是，如果要使切削液起作用就必须让它到达切屑刀具接触界面。但如何在采用单尖刀具连续车削的场合尤其是切屑-刀具接触压力高达70MPa时实现并非易事。

Merchant thought that minute asperities existed at the chip-tool interface and the fluid was drawn into the interface by the capillary action of the interlocking network of these surface asperities.Merchant认为：在切屑与刀具接触界面上存在微小的粗粒，切削液通过这些表面的微小粗粒组成连锁的网络的毛细管被吸入到切屑与刀具的接触界面上。

Unit8

Grinding is a manufacturing process that involves the removal of metal by employing a rotating abrasive wheel.The latter simulates a milling cutter with an extremely large number of miniature cutting edges.磨削是通过采用旋转磨轮去除金属的制造工艺。磨轮用非常大量的微型切削刃模仿铣刀进行切削。Generally, grinding is considered to be a finishing process that is usually used for obtaining high-dimensional accuracy and better surface finish.Grinding can be performed on flat, cylindrical, or even internal surfaces by employing specialized machine tools, which are referred to as grinding machines.一般而言，磨削被认为是一种通常用于获得高尺寸精度和较好表面光洁度的精加工作业。磨削通过采用被称为磨床的特殊机床能在平面、圆柱面甚至内表面上进行。

Obviously, grinding machines differ in construction as well as capabilities, and the type to be employed is determined mainly by the geometrical shape and nature of the surface to be ground, e.g., cylindrical surfaces are ground on cylindrical grinding machines.显然，磨床根据结构和功能的不同有所区别，使用何种形式的磨床主要取决于被磨削表面的几何形状和物理性质。例如，圆柱面在外圆磨床上磨削。Type of Grinding Operations磨削作业的类型

1.Surface grinding.As the name surface grinding suggests, this operation involves grinding of flat or plane surfaces.Fig.8.1 indicates the two possible variations, either a horizontal or vertical machine spindle.1.表面磨削：就像其名称暗示的那样，表面磨削和平面磨削直接有关。图8.1表示了两种可能的变化：卧式磨床主轴或立式磨床主轴。

In the first case(horizontal spindle), the machine usually has a planer-type reciprocating table on which the workpiece is held.However, grinding machines with vertical spindles can have either a planer type table like that of the horizontal-spindle machine or a rotating worktable.在第一种情况(卧式主轴)，卧式磨床通常具有安装工件的刨床式往复工作台。而立式主轴磨床既可以像卧式主轴磨床那样具有刨床式工作台也可以具有旋转工作台。

Also, the grinding action in this case is achieved by the end face of the grinding wheel(Fig.8.1b), contrary to the case of horizontal-spindle machines, where the workpieces ground by the periphery of the grinding wheel.而且在这种情况下，磨削动作是通过砂轮端面完成的(图8.1b)，这与通过砂轮周边磨削工件的卧式主轴磨床正好相反。

Fig.8.1a and b also indicate the equations to be used for estimating the different parameters of the grinding operation, such as the machining time and the rate of metal removal.图8.1a和b同时简述了用于估计诸如加工时间和金属去除率之类的磨削作业不同参数的方程式。During the surface-grinding operations, heavy workpieces are either held in fixtures or clamped on the machine table by strap clamps and the like, whereas smaller workpieces are usually held by magnetic chucks.在平面磨削时，重的工件用夹具固定或用压板等夹紧在磨床工作台上，而小的工件则通常是用电磁卡盘固定的。

2.Cylindrical grinding.In cylindrical grinding, the workpiece is held between centers during the grinding operation, and the wheel rotation is the source and cause for the rotary cutting motion, as shown in Fig.8.2.In fact, cylindrical grinding can be carried out by employing any of the following methods: 2.圆柱面磨削：在圆柱面磨削中，作业时工件支撑在两顶尖之间，砂轮转动是导致回转切削运动的动力源，如图8.2所示。实际上，圆柱面磨削能通过采用下列任意方法来实现：

(1)The transverse method, in which both the grinding wheel and the workpiece rotate and longitudinal linear feed is applied to enable grinding of the whole length.The depth of cut is adjusted by the cross feed of the grinding wheel into the workpiece.(1)横向方法：这种方法中砂轮与工件均旋转且采用线性纵向进给以保证能磨削整个长度。切削深度通过改变砂轮对工件的横向进给来进行调整。

(2)The plunge-cut method, in which grinding is achieved through the cross feed of the grinding wheel and no axial feed is applied.As you can see, this method can be applied only when the surface to be ground is shorter than the width of the grinding wheel used.(2)插入-切削方法：这种方法通过砂轮的横向进给完成磨削而不采用轴向进给。正如料想的那样，这种方法只在要磨削表面比所用砂轮宽度短时才使用。

(3)The full-depth method, which is similar to the transverse method except that the grinding allowance is removed in a single pass.This method is usually recommended when grinding short rigid shafts.(3)全深度方法：这种方法除了一次加工就能去除磨削余量外其它与横向方法相同。这种方法通常在磨削较短刚性轴时推荐使用。

Internal grinding.Internal grinding is employed for grinding relatively short holes, as shown in Fig.8.3.The workpiece is held in a chuck or a special fixture.Both the grinding wheel and the workpiece rotate during the operation and feed is applied in the longitudinal direction.内表面磨削：内表面磨削用于相对较短的孔，如图8.3所示。工件安装在卡盘或特殊夹具上。作业时砂轮和工件都回转并且采用纵向进给。Any desired depth of cut can be obtained by the cross feed of the grinding wheel.A variation from this type is planetary internal grinding, which is recommended for heavy workpieces that cannot be held in chucks.通过砂轮的横向进给能得到任意所需的切削深度。这种方法的一个变体是行星式内表面磨削，当工件较重不能用卡盘固定时推荐使用。

In that case, the grinding wheel not only spins around its own axis but also rotates around the centerline of the hole that is being ground.在这种情况下，砂轮不但绕自身轴线回转，同时还绕被磨削孔的中心线旋转。

Centerless grinding.Centerless grinding involves passing a cylindrical workpiece, which is supported by a rest blade, between two wheels, i.e., the grinding wheel and the regulating or feed wheel.无心磨削：无心磨削用于加工圆柱形工件，工件由托板支撑，在两轮即砂轮和调节或进给轮之间通过去。

The grinding wheel does the actual grinding, while the regulating wheel is responsible for rotating the workpiece as well as generating the longitudinal feed.This is possible because of the frictional characteristics of that wheel, which is usually made of rubber-bonded abrasive.砂轮完成实际磨削，而调节轮负责旋转工件和产生纵向进给。由于调节轮通常用橡胶粘结的磨料制成，其摩擦特性使这成为可能。

As can be seen in Fig.8.4, the axis of the regulating wheel is tilted at a slight angle with the axis of the grinding wheel.Consequently, the peripheral velocity of the regulating wheel can be resolved into two components, namely, workpiece rotational speed and longitudinal feed.正如在图8.4中所看到的那样，调节轮的轴与砂轮轴倾斜一个微小角度。因此调节轮的圆周速度可以分解为两个分量，即工件回转速度和纵向进给。These can be given by the following equations:

Vworkpiece＝Vregulating wheel×cosα

Axial feed＝Vregulating wheel×c×sinα

Where c is a constant coefficient to account for the slip between the workpiece and the regulating wheel(c=0.94~0.98).其值可由下列公式给出：

V工件＝V调节轮×cosα

轴向进给＝V调节轮×c×sinα

式中c是考虑工件和调节轮之间滑动的恒定系数(c=0.94~0.98)。

The velocity of the regulating wheel is controllable and is used to achieve any desired rotational speed of the workpiece.The angleαis usually taken from 1°to 5°and the larger the angle, the larger the longitudinal feed would be.调节轮的速度是可控的并被用于实现工件任意所需的转动速度。α角通常取1到 5°，这角度越大则纵向进给也将越大。

Whenαis taken as 0°, i.e., the two axes of the grinding and regulating wheels are parallel, there is no longitudinal feed of the workpiece.当α取0°时，即砂轮和调节轮轴线平行时，则工件没有纵向进给。Grinding Wheels 砂轮

Grinding wheels are composed of abrasive grains having similar size and a binder.The actual grinding process is performed by the abrasive grains.Pores between the grains within the binder enable the grains to act as separate single-point cutting tools.砂轮由具有相近尺寸的磨料颗粒和粘合剂组成。实际磨削作业由磨粒完成。在粘合剂中磨粒之间的孔隙使磨粒能象独立的单刃切削刀具一样工作。

These pores also provide space for the generated chips, thus preventing the wheel from clogging.In addition, pores assist the easy flow of coolants to enable efficient and prompt removal of the heat generated during the grinding process.这些孔隙同时还为产生的切屑提供空间以防砂轮堵塞。另外孔隙帮助冷却液容易流动，从而使在磨削作业中产生的热量能有效而迅速地散发。

Grinding wheels are identified based on their shape and size, kind of abrasive, grain size, binder, grade(hardness), and structure.砂轮根据它们的形状和尺寸、磨料的类型、磨粒的大小、粘合剂、等级(硬度)和结构组织来分类。

Shape and size of grinding wheels.Grinding wheels differ in shape and size, depending upon the purpose for which they are to be used.Various shapes are shown in Fig.8.5 and include the following types:

砂轮的形状和尺寸：根据砂轮的用途，它们的形状和尺寸是不同的。各种形状如图8.5所示，其中包括：

1)Straight wheels used for surface, cylindrical, internal, and centerless grinding.2)Bevelled-face or tapered wheels used for grinding threads, gear teeth, and the like.3)Straight recessed wheels for cylindrical grinding and facing.1)用于表面、圆柱面、内部和无心磨削的直轮。2)用于磨削螺纹、齿轮轮齿之类的斜面或锥形轮。3)用于圆柱面和端面磨削的直凹轮。

4)Abrasive disks for cutoff and slotting operations.(thickness 0.02 up to 0.2in.(0.5 to 5mm)).5)Cylinders, straight cups, and flaring cups are used for surface grinding with the end face of the wheel.4)用于切断和开槽作业的砂轮片(其厚度从0.02到0.2英寸(0.5到5毫米))。5)用其端面进行表面磨削的圆柱、直杯及外展杯状砂轮。

The main dimensions of a grinding wheel are the outside diameter D, the bore diameter d, and the height H.These dimensions vary widely, depending upon the grinding process for which the wheel is to be used.砂轮的主要尺寸有外径D、孔径d和厚度H。根据采用砂轮的磨削工艺，这些尺寸变化很大。

Kind of abrasive.Grinding wheels can be made of natural abrasives such as quartz, emery, and corundum or of industrially prepared chemical compounds such as aluminum oxide or silicon carbide(known as carborundum).磨料的类型：砂轮可以由象石英、金刚砂、刚玉之类的自然磨料制成，或者由象氧化铝或碳化硅(也称人造金刚砂)之类的工业制备的化学化合物制成。

Generally, silicon carbide grinding wheels are used when grinding low-tensile-strength materials like cast iron, whereas aluminum oxide wheels are employed for grinding high-strength metals such as alloy steel, hardened steel, and the like.当磨削象铸铁类低拉伸强度材料时，一般采用碳化硅砂轮，而磨削合金钢、淬火钢等高强度金属则要用氧化铝砂轮。

Grain size of abrasive used.As you may expect, the grain size of the abrasive particles of the wheel plays a fundamental role in determining the quality of ground surface obtained.所用磨粒的尺寸：正如料想的那样，砂轮磨粒的尺寸对决定所得磨削表面的质量起着根本的作用。The finer the grains, the smoother the ground surface is.Therefore, coarse-grained grinding wheels are used for roughing operations, whereas fine-grained wheels are employed in final finishing operations.磨粒越细，磨削表面越光滑。所以，粗粒砂轮用于粗加工，而细粒砂轮则用于最后精加工。

The grade of the bond.The grade of the bond is actually an indication of the resistance of the bond to pulling off the abrasive grains from the grinding wheel.Generally, wheels having hard grades are used for grinding soft materials and vice versa.粘结体的等级：粘结体的等级实际上是其抵抗将磨粒从砂轮上拉脱的指标。一般而言，具有较硬等级的砂轮用于磨削较软材料，反之亦然。

If a hard-grade wheel were to be used for grinding a hard material, the dull grains would not be pulled off from the bond quickly enough, thus impeding the self-dressing process of the surface of the wheel and finally resulting in clogging of the wheel and burns on the ground surface.如果较硬等级的砂轮用于磨削较硬材料，磨钝的磨粒将不能足够快地脱离粘结体，这会妨碍砂轮表面的自修复，最终导致砂轮的堵塞并在被磨表面留下灼斑。

In fact, the cutting properties of all grinding wheels must be restored periodically by dressing with a cemented carbide roller or a diamond tool to give the wheel the exact desired shape and remove all worn abrasive grains.实际上，所有砂轮的磨削性能都必须定期地通过使用硬质合金滚轮或金刚石修整器修整而被恢复，以求很准确地把砂轮加工成要求的形状，并去除已磨钝的磨粒。

Structure.Structure refers to the amount of void space between the abrasive grains.When grinding softer metals, larger void space are needed to facilitate the flow of the removed chips.结构组织：结构组织与磨粒间的空隙量有关。当磨削较软金属时，需要较大的空隙以便去除切屑的流动。

The binder.Abrasive particles are bonded together in many different ways.These include bond, silicate, rubber, resinoid, shellac, and oxychloride.Nevertheless, the bond is the most commonly used one.粘合剂：磨粒可用多种不同方法粘结在一起。其中包括粘合剂、硅酸盐、橡胶、树脂、虫胶和氯氧化物。然而，粘合剂是最常用的。

In fact, the standard marking system is employed for distinguishing grinding wheels, by providing all the preceding parameters in a specific sequence.在实际生产中，为了区分砂轮采用标准标注系统，通过用一特定顺序将所有上述参数都表示出来。

Unit9 Lapping 研磨

Lapping is a finishing operation used on flat and cylindrical surfaces.The lap, shown in Fig.9.1a, is usually made of cast iron, copper, leather, or cloth.研磨是一种用于平面和圆柱面的精加工作业。研具，如图9.1a所示，通常用铸铁、铜、皮革或布制成。

The abrasive particles are embedded in the lap, or they may be carried through slurry.Depending on the hardness of the workpiece, lapping pressures range from 7kPa to 140kPa(1 to 20 psi).研磨微粒嵌入研具内，或者可以通过液体携带。根据工件硬度，研磨压力可在7kPa到140kPa(1到20psi)范围中取。

Lapping has two main functions.Firstly, it produces a superior surface finish with all machining marks being removed from the surface.Secondly, it is used as a method of obtaining very close fits between mating parts such as pistons and cylinders.研磨有两个主要作用。首先，它通过去除所有机加工痕迹能产生较好的表面光洁度。其次，它能用作获得像活塞与气缸之类配件间过盈配合的方法。

The lapped workpiece surface may look smooth but it is actually filled with microscopic peaks, valleys, scratches and pits.Few surfaces are perfectly flat.Lapping minimizes the surface irregularities, thereby increasing the available contact area.研磨后的工件表面可能看似平滑，其实布满着微观峰、谷、划痕和凹陷。几乎没有表面是完全平整的。研磨使表面不规则最小化，因而增加了有效接触面积。

The drawing in Fig.9.1a shows two surfaces.The upper one is how a surface might look before lapping and the lower one after lapping.Lapping removes the microscopic mountain tops and produces relatively flat plateaus.Entire microscopic mountain ranges may need to be ground down in order to increase the available contact area.图9.1a上显示了两个表面。上面是研磨前表面可能的外观模样而下面则是研磨后的模样。研磨去除了微观峰顶从而产生相对平坦的平台。整个微观山脉范围都需要磨去以增加有效接触面积。

Production lapping on flat or cylindrical pieces is done on machines such as those shown in Fig.9.1b and 9.1c.Lapping is also done on curved surfaces, such as spherical objects and lenses, using specially shaped laps.研磨平面或圆柱面工件的生产过程是在如图9.1b和9.1c那样的机器上完成的。研磨也可采用特殊成型研具在诸如球形物体和透镜之类的曲面上进行。Polishing

抛光

Polishing is a process that produces a smooth, lustrous surface finish.Two basic mechanisms are involved in the polishing process:(a)fine-scale abrasive removal, and(b)softening and smearing of surface layers by frictional heating during polishing.抛光是生成平滑、有光泽表面光洁度的工艺。抛光工艺涉及两种基本机理：(a)精细等级磨粒去除，和(b)在抛光中通过摩擦生热软化并抹光表面层。Electropolishing

Electropolishing is an electrochemical process similar to, but the reverse of, electroplating.The electropolishing process smoothes and streamlines the microscopic surface of a metal object.Mirror-like finishes can be obtained on metal surfaces by electropolishing.电解抛光

电解抛光是一种与电镀相似的电化学工艺，但过程与电镀正好相反。电解抛光工艺使金属物体的微观表面平滑和简单化。通过电解抛光能在金属表面得到镜面光洁度。

In electropolishing, the metal is removed ion by ion from the surface of the metal object being polished.Electrochemistry and the fundamental principles of electrolysis(Faraday’s Law)replace traditional mechanical finishing techniques.在电解抛光中，金属是逐个离子地从被抛光金属物体表面去除的。电化学和电解基本原理(Faraday定理)取代了传统的机械精加工技术。

In basic terms, the object to be electropolished is immersed in an electrolyte and subjected to a direct electrical current.The object is maintained anodic, with the cathodic connection being made to a nearby metal conductor.用基本术语说，要电解抛光的物体被浸没在电解液中并且通上直流电。该物体为阳极，阴极连接到附近的金属导体上。

Smoothness of the metal surface is one of the primary and most advantageous effects of electropolishing.During the process, a film of varying thickness covers the surface of the metal.This film is thickest over micro depressions and thinnest over micro projections.金属表面的平滑是电解抛光主要的和最有优势的效应之一。在此过程中，一变化着厚度的膜覆盖在金属表面上。该膜在微观凹陷处最厚而在微观凸出处最薄。

Electrical resistance is at a minimum wherever the film is thinnest, resulting in the greatest rate of metallic dissolution.Electropolishing selectively removes microscopic high points or “peaks” faster than the rate of attack on the corresponding micro-depressions or “valleys”.电阻在膜最薄处最小，导致最大金属分解率。电解抛光选择性地去除微观高点或“峰” 快于对相应微观凹陷处或“谷”的侵蚀速率。

Stock is removed as metallic salt.Metal removal under certain circumstances is controllable and can be held to 0.0001 to 0.0025 mm.原材料以金属盐的形式被去除。在特定环境下金属的去除是可控的并且保持在0.0001 到0.0025mm范围内。

Chemical Mechanical Polishing

Chemical mechanical polishing is becoming an increasingly important step in the fabrication of multi-level integrated circuits.Chemical mechanical polishing refers to polishing by abundant slurry that interacts both chemically and mechanically with the surface being polished.化学机械抛光

化学机械抛光正在多层集成电路制造领域成为日益重要的步骤。化学机械抛光是指大量抛光液与被抛光表面产生化学和机械作用的抛光。

During the chemical mechanical polishing process, a rotating wafer is pressed face down onto a rotating, resilient polishing pad while polishing slurry containing abrasive particles and chemical reagents flows in between the wafer and the pad.在化学机械抛光过程中，旋转晶片面向下压在旋转、有回弹力的抛光衬垫上，而同时含有研磨微粒和化学反应物的抛光液流过晶片与衬垫之间。

The combined action of polishing pad, abrasive particles and chemical reagents results in material removal and polishing of the wafer surface.Chemical mechanical polishing creates flat, damage-free on a variety of brittle materials and it is used extensively on silicon wafers in the manufacture of integrated circuits.抛光衬垫、研磨微粒和化学反应物的共同作用导致晶片表面的材料去除并抛光。化学机械抛光可使多种易碎材料平整且不受损害，因此在集成电路制造中被广泛地用在硅晶片上。

Chemical mechanical polishing is a complicated multiphase process.It mainly includes the following two dynamics.First, the active component in polishing slurry reacts with the atoms of the wafer, and the process is chemical reaction step with oxidation-reductive reaction.化学机械抛光是一种复杂的多相工艺。它主要包括下列两个动态过程：第一，抛光液中活性成分与晶片的原子发生反应，这是带有氧化-还原反应的化学反应步骤。

The second step is the process of desorption, that is to say, the resultants gradually separate from the wafer

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