1.Cast iron
1.铸铁
Cast iron is a general term applied to a wide range of iron-carbon-silicon alloy combination with smaller percentages of several other elements. Cast iron has been used in various industrial fields. Fig.R1-1 shows the cylinder block made by cast iron. It is an iron containing so much carbon or its equivalent. It is not malleable. Quite obviously, cast iron has a wide range of properties, since small percentage variations of its elements may cause considerable change. Cast iron should not be thought of as a metal containing a single element, but rather, as one having in its composition at least six elements. All cast iron has still other elements, which should not be thought of as impurities, for they all have important effects on the physical properties. Pure iron, known as ferrite, is very soft and has few uses in industrial work. Regulating the elements other than ferrite in the cast iron controls all desirable properties, such as strength, hardness and machinability.
铸铁是一个总称，包括范围广泛的铁碳硅合金的结合小比例的其他几个要素。铸铁开始用于各种工业领域。图R1-1所示汽缸座用铸铁制造。这是铁含有了太多的碳或其他等效的物质。这是不可锻造的。很明显，铸铁具有广泛的性能，因为其元素的小百分比的变化可能会引起相当大的变化。铸铁不应被认为是一个金属包含一个单独的元素，而是，作为一个具有至少六个元素组成。所有铸铁含有铁，碳，硅，锰，磷，硫。合金铸铁还有其他元素，其他元素不应该被认为是杂质，因为他们所有的物理性质有重要的影响。纯的铁，称为铁素体，很软，几乎没有用于工业生产。其它元素在铸铁铁素体调节控制所有理想的性质，如强度，硬度和可锻造性。
The cast iron family includes gray, ductile (also called nodular), white, malleable and high-alloy irons.
铸铁系列包括灰口铸铁，球墨铸铁（也被称为nodular），白口铸铁，可锻铸铁和高合金铸铁。
Gray iron is itself a family of casting alloys, and is the most widely used, with an annual production several time the total for all other metals cast.
灰口铸铁本身所属的种类是铸造合金，是应用最广泛的，每年生产的总量是几倍于其他铸铁的。
A relatively new type of cast iron is ductile iron-also called nodular iron .As its name implies, ductile iron offers more ductility than gray iron, plus higher strength.
一种新型的球墨铸铁称为球墨铸铁。顾名思义，球墨铸铁具有比灰口铸铁更具延展性，加上高强度。
2.Heat Treatment of Steel
2.钢的热处理
Heat treatment is a method by which the heat treater can change the physical properties of metal .There are three main operations in the heat treatment of steel: hardening, tempering, and annealing.
热处理是热处理工作者用以改变金属物理性能的方法。钢热处理有三种法即淬火、回火和退火。
The hardening operation consists of heating the steel above its critical range and then quenching it, that is rapidly cooling in a suitable medium such as water, brine, oil, or some other liquid. Having been hardened, the metal must be given a tempering treat-ment which consists of reheating the hardened steel to a temperature below the critical range, thus producing the required physical properties.
淬火是将钢加热到临界点以上然后进行急冷。急冷是指在材料合适的介质如水、盐水、油或其他液体中快速冷却。金属在淬硬后必须进行回火处理。回火是将淬硬的钢重新加热到低于临界点的温度从而获得所需的物理性能。
The critical points or critical temperatures are the temperatures at which a certain change takes place in the physical condition of the steel. These points are very important because in order to properly harden a piece of steel, it must be heated to a temperature above the upper critical point. Having known the critical points for a certain steel, we can easily control the heat in the furnace. Gas, oil, and electric furnaces are the most commonly used for heat treating metals.
临界点或临界温度是指钢的物理性能发生某些变化的温度。这些临界点极为重要因为要使钢很好地硬化就必须把钢加热到上临界温度以上。我们知道某一钢种的临界点后就能较容易得控制炉温。煤气炉、油炉和电炉是金属热处理最普遍采用的炉子。
Annealing is the uniform heating of a metal above usual hardening temperatures, followed by very slow cooling. Annealing may be carried out either to soften a piece that is too hard to machine or to remachine a piece that has already been hardened. Annealing also relieves internal stresses produced by machining.
退火是将钢均匀地加热到通常的淬火温度以上然后极缓慢地冷却。若工件过硬无法机加工或是要重新机加工已经淬硬的零件这时可进行退火以使钢材软化。退火还可消除机加工时产生的内应力。
Low carbon steels do not become hard when subjected to such a heat treatment because of the small amount of carbon contained. If it is necessary to obtain a hard surface on a part made of such steel, surface hardening operation must be carried out. One of the methods of surface hardening is cyaniding, which is done by keeping the work in a molten bath of sodium cyanide from 5 to 30 minutes, depending on the size of the work and the depth of penetration required. Having been subjected to such a treatment, the work is then quenched in water of oil, and a very hard case 0.01 to 0.015 inch thick is formed. This process is also called case hardening.
低碳钢由于含碳量低，因此在经受这种热处理时材质不可能变硬。若欲在低碳钢制成的零件表面获得硬的表面层就须进行表面硬化处理。氰化是一种表面硬化方法。氰化时将工件
置入氰化钠的溶池中保温5至30分钟，保温时间取决于工件的尺寸和所需的渗透深度。工件经过这一处理后再将其淬入水或油中于是形成了一层厚度为0.01至0.015的十分硬的表面层。这类工艺过程也称为表面淬火。
Nitriding is also one of the case hardening methods. This process consists of keeping the steel in hot ammonia gas for some hours. Nitrogen, formed in this condition from ammonia, penetrates into the surface of the metal , thus forming a very hard case.
渗氮也是一种表面硬化法。它是将钢在热的氨气中放置数小时。在这一条件下由氨气形成的氮渗入到金属的表面从而性形成了极硬的表面层。
Another method of case hardening is carburization. The work is placed into a metal box containing carburizing materials (that is , materials with high carbon content); the box is closed and placed into a furnace for some hours at the temperature of 926 degrees Centigrade. The depth to which the carbon penetrates depend upon the length of time the piece is kept in the furnace. Having been quenched in some liquid quenching medium, the work has a hard case and a soft core.
另一种表面硬化法是渗碳。将工件装入盛有渗碳剂含碳很高的材料的金属箱中将箱子密封好并放入炉内在926°C温度下在炉中保持若干小时。渗碳层的深度取决于工件在炉中的保温时间。将工件在某种液体中淬火后其表层硬而心部软。
3.Limits and Tolerances
3.极限与公差
Machine parts are manufactured so they are interchangeable. In other words, each part of a machine or mechanism is made to a certain size and shape so it will fit into any other machine or mechanism of the same type. To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. It is not only impossible, but also impractical to make many parts to an exact size. This is because machines are not perfect, and the tools become worn. A slight variation from the exact size is always allowed. The amount of this variation depends on the kind of part being manufactured. For example, a part might be made 6 in. long with a variation allowed of 0.003 (three thousandths) in. above and below this size. Therefore the part could be 5.997 to 6.003 in. and still be the correct size. These are known as the limits. The difference between upper and lower limits is called the tolerance.
机械零件可互换。换言之，机器或机械装置的每个零件是有一定的大小和形状，因此适用于同一类型的任何其他机器或机械装置。为了使零件能够互换，每个零件作出的大小必须能准确地适用于与其匹配的零件。以确切的尺寸制作多个零件不仅是不可能的，而且也不切实际。这是因为机器并非尽善尽美，而且这些工具也会老化，确切尺寸也要允许略有误差。误差的大小取决于所生产零件的种类。例如，生产6英寸长的零件允许的差异在0.003 （千分之三）英寸上下。因此，生产出的零件的尺寸可能是5.997至6.003英寸，但这仍然属于正常尺寸范畴，此为限度，上限和下限之间的差额称为公差。
When the tolerance is in both directions from the basic size, it is known as a bilateral
tolerance (plus and minus). Sometimes the limit is allowed in only one direction. This is known as unilateral tolerance. For example, a hole may have to be 2 in. minus 0.000in., or plus 0.005 in., but can be as large as 2.005 in.
如果基准尺寸的两端产生了公差，那么这种公差即被称为双向公差(增加或减少) 。有时限度只在一个方向产生，这种行为即是单向公差。举例来说, 一个2英寸的孔，其大小可能没有减少, 也可能增加0.005英寸, 但是其大小可达2.005 英寸。
4.Shaft
4.轴
shafts were assembled form separate lengths of shafting clampled together by rigid couplings. Although it is usually more convenient to drive each machine with a separate electric motor, and the present-day trend is in this direction, there are still some oil engine receives its rotary motion from each of the cranks, via the pistons and connecting roads (the slider-crank mechanisms) , and delivers it by means of couplings, gears, chains or belts to the transmission, camshaft, pumps, and other devices. The camshafts, driven by a gear or chain from the crankshaft, has only one receiver or input, but each cam on the shaft delivers rotary motion to the valve-actuating mechanisms.
轴作为机械零件通常是一根圆柱形杆，用来支撑部件并随部件一起转动以接受和传递转动和扭矩。往复式发动机的曲轴接受每一根曲轴通过活塞和连杆（滑块-曲柄机构）传来的转动，并通过联轴器、齿轮、链条或皮带把转动传递到变速箱、凸轮轴、泵和其它装置。由曲轴通过齿轮或链条驱动的凸轮轴只有一根受力轴即输入轴，但轴上的每一个凸轮都能把转动传递给气门的传动机构。
An axle is usually defined as a stationary cylindrical member on which wheels and pulleys can rotate, but the rotating shafts that drive the rear wheels of an automobile are also called axles, no doubt a carryover from horse-and-buggy days. It is common practice to speak short shafts on machines as spindles, especially tool-carrying or work-carrying shafts on machine tools.
轮轴通常的定义是车轮和皮带轮能在其上旋转的一根固定的圆柱形构件，但驱动汽车后轮的旋转轴也叫轮轴，这可能是从过去马车时代传下来的。通常习惯上把机器上的短轴叫做主轴（或心轴），特别是指机床上安装刀具和工件的轴。
In the days when all machines in a shop were driven by one large electric motor or prime mover, it was necessary to have long line shafts running length of the shop and supplying power, by belt, to shorter coutershafts, jackshafts, or headshafts. These line shafts were assembled form separate lengths of shafting clampled together by rigid couplings. Although it is usually more convenient to drive each machine with a separate electric motor, and the present-day trend is in this direction, there are still some situation in which a group drive is more economical.
在以前一个车间里所有的机器都由一个大电动机或原动机驱动，这样就必须有一根同车间一样长的主传动轴（即天轴）通过皮带把动力供给较短的副轴、中间轴或顶轴。这种主传动轴是用一节节的轴装配起来的，用刚性联轴器固定在一起。尽管一般说来用单独的电动机
来驱动每一台机器更为方便，并且现代的趋势也是按照这个方向发展的，但现在仍有某些场合采用分组传动更为经济。
5.cutting tool
5.切削刀具
The metal cutting tool separates chips from the workpiece in order to cut the part to the desired shape and size.See Fig.R5-1. there are a great deal of metal cutting tools .Each of them is designed to perform a particular job or a group of metal cutting operations in an efficient manner .For example ,a twist drill is designed to drill a hole ,which has a particular size, and a turning tool may be used to turn a variety of cylindrical shapes.
金属切削刀具用来切割所要求的形状和尺寸的工件。见图R5-1。有大量的金属切削刀具。它们每一个被设计来执行特定的工作或一组的金属切削操作用一种有效的方式。例如，麻花钻用来钻一个孔，其中有一个特定的大小，和车削刀具可以用来打开各种圆柱形状。
There are three basic types of metal cutting tools : single point tools ,multipoint tools and abrasives . A single point metal cutting tool has a single cutting edge and is used for turning . boring ,shaping and planing , The most common machine tools have two or more cutting edges such as drills ,reamers and milling cutters, the cutting edge is that part of the tool where cutting is actually done. Grinding wheels are an example of abrasive cutting tools ,Each grinding wheel has a lot of abrasive grains, which act as very small tools.
这里有三种基本类型的刀具：单刃刀具，多刃刀具、磨料磨具。单刃刀具有一个单一的切削刃和用于车削。镗削，刨削，最常见的机床有两个或两个以上的切削刃如钻头，铰刀和铣刀，切削刃的那一部分实际是在切割工具上做的。砂轮是磨粒切削工具的一个例子，每个砂轮有很多磨粒，作为非常小的工具。
6.The Function of Tooling
6.模具的功能
The equipment, small or large, simple or complex, that adapts the production machine to the production of a specific part is known as tooling.
使高效机床适应于加工某一特定零件的那种设备，无论其大小如何，简单复杂与否，均称作为工夹具。
Machining requires two kinds of tooling; working-holding devices such as drills press vise; and cutting tooling, such as drills and reamers. Working-holding devices are called jigs and fixtures. The two terms are often used interchangeably, but they have different meanings, a jig is a working-holding devices that is not fastened to the machine ;while a fixture is fastened to machine .a familiar type of jig or fixture is the frill press vise that is used to hold work in position
for light drilling operations, such as vise is a general purpose or universal fixture and does not constitute a tooling charge against the job.
机械加工需要两种工具：工件夹持装置如钻压钳和刀具如钻头、铰刀。工件夹持装置称为夹具。这两个术语经常交替使用，但它们有不同的含义，一个移动夹具是工件夹持装置，不固定在机器上；而一个固定夹具固定在机器上。一个熟悉类型的移动夹具或固定夹具是钻压钳是用来稳定工作位置来钻孔操作，如老虎钳是一种一个通用的或普遍的夹具和不构成对工作的危害。
Most of the machining we do in a machine shop is done with cutting tools. A cutting tool is a hardened piece of metal or other material. Cutting tools are made in a wide variety of shapes and sizes. Each of them is designed for a specific purpose.
我们在车间进行的大部分加工是用刀具来完成的。刀具是一块具有切削刃的淬硬金属或其他材料。刀具制成各种尺寸，每种有每种的用途。
9.Coordinate measuring machines
9.坐标测量机
Coordinate measuring machines, commonly referred to as CMM, are flexible dimensional measuring devices. See Fig. R9-1.CMM is widely used for the post-process inspection of machines, molded and fabricated components. CMM operates with the aid of three perpendicular axis measuring scales and a special contact-sensitive probe to detect the surface of the component.
坐标测量机，通常被称为CMM，是柔性的三维测量装置。见图。R9-1。CMM被广泛用于机器的后期检测，模塑和制造的组件。坐标测量机用三个垂直轴的测量尺的帮助和一个特殊的接触敏感的探测器，以检测元件的表面。
When a component is to be inspected, it is positioned on the CMM table, and the contacting stylus of the probe is moved to touch the appropriate feature of the part. This is completed by moving the axis slides to which are attached the measuring scales. The scales are read at the point of probe contact to determine the X, Y and Z Coordinates of the position in question with respect to some reference point in the instrument working space.
当一个组件进行检查，它的位置是在CMM工作台上，和接触的尖端移动到相应的部分。这是通过移动所述轴完成滑动到它们分别连接的测量尺度。鳞时读取的探针接触点来确定X，Y和有问题的位置的Z轴坐标相对于所述仪器的工作空间中的一些参考点。
The level of CMM automation varies widely. The most sophisticated machines are capable of fully automated inspection and reporting of results. The computerized CMM can analyze the component dimensions to determine, out-of-tolerance condition, and use techniques to determine capability and trends.
CMM自动化水平差别很大。最复杂的机器能够完全自动化的检查和报告的结果。电脑CMM可以分析组件尺寸确定,超差条件,并利用技术来确定能力和趋势。
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