2.Elastomers An elastomer is defined as any polymeric material that can be stretched at room temperature to at least twice its original length and return to its original length after the stretching force has been removed. Elastomers are able to store energy, so they can return to their original length and/or shape repeatedly. Elastomers have a molecular, amorphous structure similar or that of other polymeric materials. This amorphous, or shapeless, structure consists of long coiled-up chains of giant molecules(polymers)that are entangled with each other. Adjacent polymers are not strongly bonded together. When a tensile force is applied, these coils straighten out and snap back like springs to their original coiled condition on removal of the force. 弹性体是指任何高分子材料，可在室温下延伸到至少两倍原来的长度和拉伸力后，返回到原来的长度已被删除。弹性体能够存储能量，这样他们就可以回到原来的长度和/或形状反复。弹性体的分子，无定形结构相似或其他聚合材料。这种含糊不清的，或无形的，结构由长期盘绕组成（聚合物）是相互纠缠大分子链。相邻聚合物不强粘合在一起。当施加拉力，这些线圈整顿和类似弹簧弹回其原来的清除缠绕条件。
3.Most of the groups of the family of materials could be classed as composites because of the way they are placed in service; the composite classification commonly refers to material developed to meet the demands in building, electronic, aerospace, and auto industries. With an even increasing use of composites, they are truly the material of today and the near future because composites can be designed to be stronger, lighter, stiffer, and more heat resistant than natural materials or to possess properties required by technology that are not available in a single material. 材料家族的大多数类型可以归为合成物，根据它们应用的场合，合成物的分类一般指的是应用在建筑，电子，航空宇宙和汽车工业上材料。随着合成物应用的越来越多，实际上，它们已经成为目前以及不久的将来使用的主要材料；因为它们可以被设计成更强的，更轻的，更硬的以及更好的耐热性的材料，而且拥有单一的天然材料不具备的工艺特性。
4. Mechanical Property of Materials In selecting a material for a product such as a piston in an internal combustion engine, a designer is interested in properties such as strength, ductility, hardness, or fatigue strength. 在为一个产品选择材料上，比如内燃机上的一个活塞，一个设计者感兴趣的特性是材料的长度，延展性，硬度或者疲劳强度等。 Mechanical properties are defined as a measure of a material’s ability to carry or resist mechanical forces or stresses. 机械特性被定义为衡量材料抵抗机械载荷或者压力性能的指标。 When any matter is at rest, the atomic or molecular structure is in equilibrium.当任何材料在静止状态时，原子或分子结构保持着平衡。 The bonding forces in this structure resist any attempt to disrupt this equilibrium.
它们之间的结合力阻止任何破坏这种平衡的意图。 One such attempt may be an external force or load. 一个这样的意图也许是一个外力或外载荷。Stress results from forces such as tension, compression, or shear that pull, push, twist, cut, or in some way deform or change the shape of a piece of material.应力产生于拉伸，压缩，或者拖，推，扭，削之类的剪切，或者某种变形以及材料的部分形状改变
5.The yield point represents the dividing line or transition from the elastic to the plastic region of the curve. 屈服点代表了弹性变形区域到塑性变形区域之间的分界线。 When the stress reaches the yield point, a large increase in strain occurs with no increase in stress. 当应力达到屈服点，应变会急剧增大而应力保持不变。 The modulus, modulus of elasticity in tension, or coefficient of elasticity is the ratio of the stress to the strain in the elastic region of the stress-strain diagram. 模量，拉伸载荷下的弹性模量，也就是应力-应变图中弹性变形区域的应力与应变之比，也称为弹性系数。 The tensile modulus approximately equal to the compressive modulus of elasticity within the proportional limit. 拉伸载荷模量约等于比例极限内的弹性模量。 This modulus is an indication of the stiffness of the material when subjected to a tensile load.
这个模量反映的是材料在受到拉伸载荷时的硬度指标。 The stiffness of a material is defined as the ratio of the load to the deformation produced.
6.Ductility 延展性
A material that can undergo large plastic deformation without fracture is called a ductile material一种可以经受较大的塑性变形而不发生破裂的材料叫做塑性材料。 A brittle material, on the other hand, shows an absence of ductility. 另一方面，脆性材料是没有延展性的。 Consequently, a brittle material shows little evidence of forthcoming fracture by yielding, as a ductile material would do. 因此，当接近屈服时脆性材料并不会出现即将破裂的迹象，而塑性材料却是这样的。 A ductile material, by yielding slightly, can relieve excess stress that would ultimately cause fracture. 脆性材料通过轻微地屈服可以减少多余的压力，以免形成最终的破裂。 This yielding can be accomplished without any degradation of other strength properties.在别的强度特性不减退的情况下，这个区服过程是可以减退的。
7.Creep(Creep Strength) 抗蠕变强度
Creep is a slow process of plastic deformation that takes place when a material is subjected to a constant condition of loading(stress) below its normal yield strength After a certain amount of time has elapsed under constant load, the creep strain(plastic deformation) will increase and some materials will rupture, or fracture, is known as creep rupture Creep occurs at any temperatures. However, at low temperatures, slip is impeded by impurity atoms and grain boundaries. At high temperatures, the diffusion of atoms and vacancies permits the dislocations to move around impurity atoms and beyond grain boundaries, which results in much higher creep rates. Different types of materials have different creep characteristics, dependent on the structure of materials.
蠕变是一种缓慢的塑性变形过程，当材料受到常规屈服强度以下的恒定载荷或应力时，蠕变就会产生。当经受一段时间的恒定载荷之后，蠕变应变（塑性变形）将会加剧，一些材料将会出现破裂或断裂，这就是蠕变破裂。蠕变在任何温度条件下都可以发生。然而，低温下，滑移会被杂质原子和晶体界限所阻碍。高温时，原子的扩散导致空间产生混乱而在杂质原子四处移动以及游离于晶体界限之外，这就大大提高了蠕变产生的几率。不同种类的材料具有不同的蠕变特性，取决于它们的结构。
8. Obstacles to change Switching from traditional materials such as steeland concrete to newer materials such as plastic-based composites seems a simple, straightforward approach for the contemporary designer. 从钢铁和混凝土等传统材料切换到较新的材料，如塑料复合材料的对当代设计者是似乎简单、直接的方法。The newer materials are often superior, but sometimes there are complications 较新的材料往往性能更优越，但有时有并发症。Often, lack of experience with new materials causes hesitation by designers. 通常情况下，新材料与经验不足导致由设计师设计的犹豫。Departures from tried-and-true materials may be costly.偏离有经验的材料可能代价高昂。It requires time before both designers and fabricators gain sufficient experience to become comfortable with new materials and the associated processes required to make products or systems.它需要设计者和加工者获得使产品或系统成为舒适与新材料及相关的流程所需的足够经验。This problem is exacerbated when human life might be in jeopardy, such as when designing for aircraft. 此问题加剧时人类的生活可能陷入困境，如设计的飞机时。Consequently, new materials and processes are usually slower to enter the marketplace than might be expected. 因此，新的材料和工艺是进入市场上通常比预期慢These issues are all a part of engineering problem solving.这些问题是工程问题需要解决的一部分Materials selection is a problem-solving issue that requires an algorithm for its solution.材料选择是为其解决方案找到一种算法的问题
9. More often than not, cost is the primary selecting criterion that will determine he final choice of material.材料成本的主要选择标准通常将决定材料的最后决定。In other words, if several materials have the specified physical, mechnical, and chemical properties, and are suitable for the processing technique selected, the lower-cost materials would be the logical choice. 换句话说，如果几种材料有指定的物理、力学、和化学特性，适合于所选的加工技术，成本较低的材料将是合理的选择。Determining cost is not as simple as it may seem.确定成本并不像看上去那么简For example,avarietyofplastics,includingPETandHDPE,have replacedglassascontainersforsoftdrinks,milkandjuices. 例如，塑料、聚酯和高密度聚乙烯，包括各种已经取代玻璃容器的软性饮料、牛奶和果汁。Although the initial cost of plastic may be greater, the plastic bottles provide savings due to their toughness (less breakage) and the savings in shipping (PET and HDPE are much lighter than glass bottles).虽然塑料的初始成本可能会更大，塑料瓶提供节省因其韧性(少破损）和航运储蓄（宠物和高密度聚乙烯是比玻璃瓶的轻得多）
10. Introduction Machining aims to generate the shape of work-piece from a solid body,or to improvethe tolerance and surface finish of a previously formed work-piece,by removing excess materials in the form of chips.Machining iscapable of creating geometric configurations,tolerances,and surface finishes often unobtainable by any other technique. However,machining removes materials,which has already been paid for,in the form of relatively small particles that are more difficult to recycle and are in greater danger of becoming mixed.Therefore, developments often aim at reducing or-if at all possible-eliminating machining,especially in mass production.For these reasons,machining has lost some important markets,yet,at the same time,it has also been developing and growing and especially having captured new markets with the application of numerical control. Some feel for the important of machining may be gained from the observation that in 1983 there were about 2 million metal-cutting machine tools in the UniteStates(of which some 5% were numerically controlled)and that labor and overhead costs amounted to $125 billion,or 3% of the GNP.
简介
机械加工是通过以碎片的形式去掉多余的材料使毛坯变成工件的形状，或者是提高上一道工序中工件的尺寸精度和表面质量。机械加工通常不需要其他的技术就能生产特定集合形状、尺寸和表面质量的产品。但是加工去掉的那些已经购买的材料，形状相对来说都非常小所以很难循环使用，而且混合起来更加危险。因此，生产特别是大批生产的发展方向是减少或者完全不需要加工。由于这些原因，机械加工失去了一些重要的市场，但与此同时，机械加工也在发展和进步，也别是在数控这些新兴市场有所应用。从1983年的一份调查中能感觉到机械加工的一些重要性，在美国，大约有200万台金属切削机床（有5%是数控机床）和那些体力劳动以及管理花费总计1250亿美元，或3%的GNP。
11. Milling Machine Milling is one of the versatile cutting processes. It can all classify according to the orientation of tool relatively to the work-piece. Horizontal mills have the axis of the cutter parallel to the work-piece surface. The cutter axis is usually horizontal, with both ends of the cutter supported. Vertical mills have the axis of the cutter perpendicular to the work-piece surface. The cutter axis is used to be vertical, but in newer CNC machine it is often horizontal. The cutter is always cantilevered (supported at one end only). The milling machines mainly used in engineering workshops are (a) Knee type machine; (b)Fixed-bed production machine; (c)Plano-millers. The various feed motions of a milling machine may be controlled by hand although the milling of complex shapes requires considerable skill. For quantity production, the milling machine can be automated to various degrees. 铣床.铣床是一种通用的加工过程。铣床能够按刀具相对工件的位置进行分类。卧式铣床的铣刀轴线和工件表面平行。刀具通常为水品，刀具两端都有支撑。立式铣床的铣刀轴线和工件
表面垂直。铣刀轴线通常是垂直的，但是最新的数控铣床是水品的。铣刀通常是悬臂形式
（一端支撑）。车间中用的铣床主要有（a）立式铣床；（b）卧式铣床；（c）龙门铣床。
通过手来控制铣床各种各样的进给运动，铣削复杂的形状需要很高的技巧。对于大量生产，
铣床有不同的自动化程度。
12. Other Machine Tools Shaping machine are designed to generate flat surfaces by means of one or more single-point cutting tools. During the cutting operation the relative motion between the tool and the work-piece is in a straight line.In shaping machines, the work-pieceis stationary during cutting, whiles the tool reciprocates, the cut being taken in one direction only while the feed is normally provided by moving the work. The earlier shaper had stationary or fixed worktable and the reciprocating head traveled sideways across the work to give feed. This type is still in use but has largely been supplanted by the modern type in which the reciprocating head has no sideways motion, the feed being obtained by moving the worktable. In both cases the depth of cut is provided by additional slide, mounted on the end of the ram and carrying the tool post.
其他的机床牛头刨床是用一把或多把单点切削刀具加工平面的机床。在切削过程中，刀具和工件的相
对运动为直线运动。牛头刨床工作过程中，工件在切削过程中固定，刀具往复运动，切削只发生在一个刀具的运动方向上，同时提供进给。早期的工作台固定，当刨刀运动到一边时进行进给运动。这种方式仍在使用，但是已经大量的被现代的方式所取代——往复运动的刀具不再向一侧运动，进给包含在工作台的移动中。在这两种方式中，切削的深度决定于安置在撞锤一端的刀架的滑行距离。
15.Gauges
When making measurements it is often convenient to place the workpiece on some accurately flat datum surfaces, such as a surface plate, which is generally an iron casting having an accurately flat horizontal upper surface. The method of finishing the upper surface depends on the accuracy of flatness required; the highest grade plates have a lapped, scraped,or ground finish,but where such precision is not required a planed surface is adequate. A toolmaker's flat is a circular hardened steel surface plate having a high-quality lapped finish.
量具。把工件放在平基准面上测量是方便的，如划线台，划线台一般是一个具有很 精确的上表面的铸铁。上表面的精加工方式取决于所需的平面度，最高精度的平板可以由研磨、刮研或者精磨加工得到，但是这样的精度往往是不需要的，并且刨削平面度足够了。
16.Introduction
Electrochemical machining (ECM) is a machining process which relies on the removal of atoms from the surface of a workpiece .Unlike ion beam machining, in which atoms are removed by transfer of momentum from the impinging ions as they strike the workpiece surface,ECM is an electrolytic process,with metal removal being achieved by electrochemical dissolution of an anodically polarized workpiece,one part of an electrolytic cell.
电解加工(ECM)是一个加工过程依赖于从工件表面移除原子的加工方法。离子束加工中,原子被转移的动力是从碰撞离子撞击工件表面获得，
ECM是电解过程,金属切削被通过电化学溶解的变形极化工件,一个部分一个电解池。
17.Figure 17.2 shows industrial electrochemical machines. the working principies of which are based on the principle given above. A small 500A machine is suitable for the machining of light items. For instance for deburring and hole drilling. Such a machine needs the components given in Figure 17.2. particular attention has to be paid to the stability of the electrochemical machine tool frame, and to be filtered carefully to remove the products of machining and often has to be heated in its reservoir to a fixed temperature, for instance 30℃. This procedure is used to provide constant operating condition, as during machining the electrolyte heats up, due to the passage of current. If precautions are not taken the high electrolyte temperature can cause too great changes in its specific conductivity, with subsequent undesirable effects on machining accuracy.
图17.2显示了工业电化学机器.工作原理是基于上述原则. 一个小于500A机器适用于加工零件的光滑度。例如对去毛刺和孔钻探。这种机器需要组件图17.2中给出。特别注意支付稳定的电化学机床框架,和被过滤删除产品的精心加工和经常需要加热的水库一个固定的温度,例如30℃。这个程序是用来提供恒定运行条件,在加工过程中电解液加热,由于通道的电流。如果不采取预防措施的高电解质温度会引起太大的变化在其特定的电导率,随后的不良影响加工精度。
18
The main machining action is carried out in the inter-electrode gap formed between the leading edge of the drill toll and the base of the hole in the workpiece.主要加工是在电极间间隙进行了钻具的前沿和工件内孔之间形成的基础。EMC also proceeds laterally between the sidewall of the toll and component. EMC同时进行横向和侧壁之间组件的加工。Since the lateral gap width is larger than that at the leading edge of the toll the side ECM rate is lower.因为侧间隙宽度比上的领先地位造成ECM效率较低。The overall effect of the side ECM is to increase the diameter of the hole that is produced.ECM的整体效果是增加所生产空的直径。The local difference between (a) the radial length between the sidewall of the workpiece and the central axis of the cathode-toll,and (b) the external radius of the cathode,is known “overcut”.当地的差异(a)径向长度的侧壁之间的工件和轴的阴极数,和(b)外部半径的阴极,就是众所周知的“超长”。The amount of overcut can be reduced by several means.超长的数量可以减少几个丝。A common method is by reversal of the direction of flow of the electrolyte,which is pumped down between the outer wall of the cathode-toll,across the main machining gap and then upward by through the central bore of the drilling-toll.一个常用的方法是在逆转的方向流动的电解液,输送到阴极在外壁之间的主要的加工间隙,然后向上通过孔完成钻孔。The overcut can also be reduced by electrical insulation of the external walls of the tool which thereby stops side current flows.也可以通过电绝缘材料减少侧面的电腐蚀。
19
Metal erosion by spark discharges was first observed by Sir Joseph Priestley as early as 1768.
在1768年由电火花放电而产生的金属腐蚀首次被Joseph Priestley发现。
More than a hundred years were to elapse before some practical use was made of the effect.
在实际应用前已经有一百多年过去了。Spark discharges became used increasingly for the disintegration of various metals to produce colloidal solutions, and for the removal of broken taps, drills and reamers.
火花加工逐渐被使用到拨离各种金属以产生胶状溶液，或者移走断的丝锥、钻头、刀具。
Nowadays spark erosion is well known as an effect that occurs with contact breaker points and the sparking plug electrodes in cars: the spark passing between the two electrical contacts causes the removal of a tiny amount of material from each of them. 如今，在汽车业接触断臂点和火花塞电极的出现让我们了解到火花腐蚀：火花在两电极接触间通过，使它们一部分微小材料的去除。
A technique that is increasingly employed in EDM applications especially for die production is orbiting of the tool-electrode.一种技术被越来越多地用于特别是模具生产应用电火花加工工具电极的发展局势。This device enables the tool-electrode to sweep a large or more intricate path then would be obtained from simply sinking the electrode in a straight operation.借助该设备，工具电极扫大型或更复杂的路径，然后将获得从简单的下沉电极在一条直线的操作。It enable several different sizes of holes with one electrode；alternatively a single tool can be used both for roughing，which requires a large gap，and for finishing which needs a smaller gap.它使一个电极孔的几种不同的尺寸；另外一个单一的工具可用于粗加工，这需要一个大的差距，以及加工需要一小的间隙。Indeed finishing can be faster because the orbiting electrode can produce a series of intermediate steps instead of a single roughing and finishing operation.事实上整理可以更快，因为绕电极可产生一系列的中间步骤，而不是一个单一的粗加工和精加工操作。The final slow finishing operation then removes much less materials than would be machined if there were only two steps.最后缓慢精加工然后删除更少材料，整个过程只有两个步骤。
20. laser machining is hased on principles that were only recently discovered.the word “laster” is an acronym of light amplification by simulated emission radiation.the process depends on the interaction of an intense,form which material is removed by vaporization.the explanation of atomic phenomena given are a useful basis for understanding laser effects. 激光加工的基本原理是近期才发现的。激光这个词是“模拟辐射使光放大”首字母的缩写。这个加工过程取决于高强度、高方向性、相干性的单色光与工件的相互作用，并使这个工件材料以气化的方式去除。原子现象的解说有利于理解激光效应。
21. A condition called optical piping, which affects the profile of the hole,frequently arises in drilling. The effect arises from theinternalreflection of laser light as the hole becomes progressively deeper. Normally the laser light is focused at the surface of the hole. The light subsequently diverges on entering the hole, and is reflected from its walls,owing to the small angle of incidence there. One example of effect of optical piping is observed from Figure 19.3 a) and b). In this work, attempts were made to re-focus the laser beam after each pulse in order to obtain a deeper hole than would have otherwise been achieved.
在钻孔过程中出现被称作光管效应的状况影响空的外形，这个效应的出现是由于当孔很深时激光的内部反射产生的，通常激光聚焦在孔的表面。接着进入孔后发散，并且由于入射角很小，孔壁使激光反射。光管效应的实例如图19.3a）和b）所示。与其他加工方法相反，每次脉冲以后，要进行一系列的努力重新聚焦，以获得更深的孔。
22.The prospects of using high frequency sound waves for machining were noted as early as 1927 by Wood and Loomis;the first patents on this subject appeared in 1945,filed by Balamuth Whilst investigating the ultrasonic grinding of abrasive powders Balamuth found that the surface of a container holding the abrasive suspension disintegrated when the tip of an ultrasonically vibrating transducer was placed close to it. Moreover, the shape of the cavity so produced accurately reproduced that of the tip of transducer. A wide range of brittle materials, including glass ,ceramic and diamond could be effectively treated in this way. 利用高频声波加工的前景，早在1927年由木材和卢米斯提出这个问题，他是出现在1945年的第一项专利，由Balamuth申请，Balamuth发现调查超声波研磨磨料粉，磨料悬浮液在容器表面崩解时，尖端的超声波振动换能器放置在靠近它的地方。此外，模腔的形状以便产生换能器的前端准确地再现。广泛的脆性材料，包括玻璃，陶瓷和金刚石可以有效地以这种方式处理。
22.5A wide range of other applications has been discussed by various workers. These include the threading of ceramics, lapping, broaching and deburring .The latter author also discusses the use of USM in materials such as rock,bones and teeth.. Kaczmarek describes USM for parting and cutting of semiconductor materials, such as geranium and quartz, commenting that the processes yields high accuracy and machining rates in comparison with established methods with much smaller numbers of rejected components. 范围广泛的其他应用程序已经被各种工人讨论。这些措施包括螺纹陶瓷，研磨，拉床和去毛刺，后者的作者也讨论了使用的材料，如石头，骨头和牙齿的USM..卡兹玛瑞克描述USM的切断和切断的半导体材料，如天竺葵和石英，评论过程拒绝和元件更小的数字比较，与已建立的方法来产生高精确度和加工率。
One of the most significant factors in manufacturing costs is production volume. Large production volumes require high production rates. High production rates require the use of mass-production techniques, involving special machinery and proportionately less labor, and plants operating on two or three shifts per day.On the other hand,s mall production bolumes usually mean large direct labor involvement. Figure 23.1 shows a downward trend in the unit-cost curbes as production volume increases. This result reflects proportionately lower tooling and capital costs per piece.Once the tooling is made,a greater number of produced parts will lower the cost of tooling per part.At low production volumes, material costs are low relative to direct labor costs, whereas at high volumes, the opposite is true.
23.在制造成本中最重要的因素是生产量。大批量生产要求高的生产效率。高生产速率要求使用大规模生产技术，涉及专用机械比例较少的劳动力，和植物，每天两班或三班。另一方面，小产量通常意味着大的直接劳动参与。图23.1显示随着产量的增加，单位成本曲线呈下降趋势。这个结果反映的工具和资金比例降低单件成本。一旦工装，更大数量的生产的零件会降低每部分工装成本。产量低，材料成本是相对较低的，直接劳工成本高，而在高产量，事实正好相反。
24.as described in previous section，small batch production is usually done on general purpose machines在上一节中描述的，小批量的生产通常是一般用途的机器做的 such as lathes， milling machines ，and hydraulic presses如车床，铣床，液压机 the equipment is versatile，and parts with different shapes and sizes can be produced by appropriate changes in the tooling该设备是通用的，并具有不同的形状和大小的部分可以通过在工具中产生适当的变化 however ，direct labor costs are high because these machines are usually operated by skilled labor然而，直接劳动成本高是因为这些机器通常由劳动熟练操作 for larger quantites ，these general purpose machine can be equipped with various jigsand fixtures ，or they can be computer controlled 较大的数量，这些通用机可配备各种jigsand夹具，也可以是计算机控制 to reduce labor costs further machining centers and flexible manufacturing systems have developed 为了减少劳动力成本进一步加工中心和柔性制造系统的开发 for quantities and perform a variety of specific operations with very little labor involved数量和非常小的劳动参与执行各种具体操作
25.the introduction of automation and up to date technology in a manufacturing factility is an obvisous means of reducing costs自动化的介绍和最新的技术在制造装置是降低成本的一个显著的手段 these changes must ，however ，be considered with care abd after thorough cost or benefit analyses，with reliable data input and due consideration of technical as well as human factors 这些变化必须，然而，被考虑的，经过深入成本或效益分析，提供可靠的数据输入和适当考虑技术以及人的因素 implementation of high technology ，which can be very expensive，should be made only after full assessment of the more obvious cost factor高技术的实现，它可以是非常昂贵的，应该只有在更明显的成本因素的充分评估
26.undoubtedly you have noted that ，over time ，the costs of products such as calculators， computers，and digital watches have decreased，whereas the costs of other products such as automobiles aircraft ，houses and books have gone up 毫无疑问，你已经注意到，随着时间的推移，产品如计算机，计算机的成本，和数字手表有下降，而其他产品，如汽车的成本飞机，房屋和书了these differeces result form the changes in various costs over time ，including labor ，machinery ，materials ，market demand， domestic and international competition ，and worldwide economic rends，and the inevitable impact of computers on all aspects of product design and manufacturing这些不同结果的形式随着时间的推移，各种成本的变化，包括劳动力，机械，材料，市场需求，国内和国际竞争，世界范围的经济发展，必然影响和计算机对产品设计和制造的所有方面
Copyright © 2019-2025 51dongshi.net 版权所有
违法及侵权请联系：TEL:177 7030 7066 E-MAIL:11247931@qq.com 本站由北京市万商天勤律师事务所王兴未律师提供法律服务
