机械类专业英语阅读教程lesson15
机械工程专业英语 第一课文及阅读材料
Lesson1 the mechanical design process 1, the mechanical design processThe ultimate objective of mechanical design is to produce a useful product that satisfies the needs of a customer and that is safe ,efficient, reliable, economical, and practical to manufacture .think broadly when answering the question ,”who is the customer for the product or system I am about to design?”it is essential that you know the desires and expectations of all customers before product design. marketing professionals are often employed to manage the definition of customer expectations , but designers will likely work with them as a part of a product development team .many methods are used to determine what the customer wants. One popular method , called quality function deployment or QFD , seeks(1) to identify all of the features and performance factors that customers desire and (2) to assess the relative importance of these factors. the result of the QFD process is a detailed set of functions and design requirements for the product.It is also important to consider how the design process fits with all functions that must happen to deliver a satisfactory product to the customer and to service the product throughout its lift cycle. in fact, it is important to consider how the product will be disposed of after it hasserved its useful life . the total of all such function that affect the product is sometimes called the product realization process or PRP . some of the factors included in PRP are as follows:1 marketing functions to assess customer requirements2 research to determine the available technology that can reasonably be used in the product3 availability of materials and components that can be incorporated into the product4 product design and development5 performance testing6 documentation of the design7 vendor relationships and purchasing functions8 work-force skills9 physical plant and facilities available10 capability of manufacturing systems11production planning and control of production systems12production support systems and personnel13 quality systems requirements14 sales operations and time schedules15 cost targets and other competitive issues16 customer service requirements17 environmental concerns during manufacture , operation anddisposal of the product18 legal requirements19 availability of financial capitalCan you add to this list? You should be able to see that the design of a product is but one part of a comprehensive process. in this text, we will focus more carefully on the design process itself , but the producibility of designs must always be considered . this simultaneous consideration of product design and manufacturing process design is often called concurrent engineering.2 skills needed in mechanical designProduct engineers and mechanical designers use a wide range of skills and knowledge in their daily work . these skills and knowledge are included in the following :1sketching, technical drawing , and computer-aided design2 properties of materials, materials processing, and manufacturing processes3 applications of chemistry, such as corrosion protection, plating , and painting4 statics, dynamics, strength of materials , kinematics, and mechanisms5 fluid mechanics, thermodynamics, and heat transfer6 fluid power, the fundamentals of electrical phenomena, andindustrial controls7 experimental design and performance testing of materials and mechanical systems8 stress analysis9 specialized knowledge of the behavior of machine elements, such as gears, belt drives, chain drives, shafts, bearings, keys, splines, couplings, seals, spring, connections(bolted, riveted, welded, adhesive), electric motors, linear motion devices, clutches, and brakes10 creativity , problem solving ,and project management11 oral communication, listening, technical writing, and teamwork skills3 functions , design requirements and evaluation criteriaSection 1 emphasized the importance of carefully identifying the needs and expectations of the customer prior to beginning the design of a mechanical device. you can formulate these by producing clear , complete statements of functions, design requirements , and evaluation criteria:1 Functions tell us what the device must do , using general , nonquantitative statements that employ action phrases such as “to support a load”, “to lift a crate ”, “to transmit power”, or “to hold two structural members together”, etc2 Design requirements are detailed, usually quantitativestatements of expected performance levels, environmental conditions in which the device must operate, limitations on space or weight , or available materials and components that may be used3 Evaluation criteria are statements of desirable qualitative characteristics of a design that assist the designer in deciding which alternative design is optimum-that is , the design that maximizes benefits while minimizing disadvantagesTogether these elements can be called the specifications for the designMost designs progress through a cycle of activities are outlined in figure1.1. you should typically propose more than one possible alternative design concept. This is where creativity is exercised to produce truly novel designs .Each design concept must satisfy the functions and design requirements . a critical evaluation of the desirable features, advantages, and disadvantages of each design concept should be completed . then a rational decision analysis technique should use the evaluation criteria to decide which design concept is the optimum and , therefore , should be produced.Reading materialMechanical design is the process of designing and/or selecting mechanical components and putting them together to accomplish a desired function. Of course machine elements must be compatible ,must fit well together , and must perform safely and efficiently. The designer must consider not only the performance of the element being designed at a given time , but also the elements with which it must interface.To illustrate how the design of machine elements must be integrated with a larger mechanical design , let us consider the design of a speed reducer for the small tractor . suppose that,to accomplish the speed reduction ,you decide to design a double-reduction, spur gear speed reducer. You specify four gears , three shafts , six bearings, and a housing to hold the individual elements in proper relation to each other. The primary elements of the speed reducer are :1 the input shaft is to be connected to the power source, a gasoline engine whose output shaft rotates at 2000 rpm . a flexible coupling is to be employed to minimize difficulties with alignment .2 the first pair of gears, a and b ,causes a reduction in the speed of the intermediate shaft proportional to the ratio of the numbers of teeth in the gears. Gear b and c are both mounted to intermediate shaft and rotate at the same speed .3 a key is used at the interface between the hub of each gear and the shaft on which it is mounted to transmit torque between the gear and the shaft .4 the second pair of gears , c and d ,further reduces the speed of gear d and the output shaft to the range of 290 rpm to 295 rpm .5 the output shaft is to carry a chain sprocket.the chain drive ultimately is to be connected to the drive wheel of the tractor.6 each of the three shafts is supported by two ball bearings .making them statically determinate and allowing the analysis of forces and stresses using standard principles of mechanics.7 the bearings are held in a housing that is to be attached to the frame of the tractor . note the manner of holding each bearing so that the inner race rotates with the shaft while the outer race is held stationary.8 seals are on the input and output shafts to prohibit contaminants from entering the housing .9 details of how the active elements are to be installed , lubricated, and aligned are only suggested at this stage of the design process to demonstrate feasibility .one possible assembly process could be as follows.Start by placing the gearing the gears, keys, spacers, and bearings on their respective shaftsThen insert input shaft into its bearing seat on the left side of the housing.Insert the left end of intermediate shaft into its bearing seat whileengaging the teeth of gears a and b.Install the center bearing support to provide support for the bearing at the right side of input shaft.Install output shaft by placing its left bearing into the seat on the center bearing support while engaging gears c and d.Install the right side cover for the housing while placing the final two bearings in their seats.Ensure careful alignment of the shafts.Place gear lubricant in the lower part of housing .The arrangement of the gears, the placement of the bearings so that they straddle the gears , and the general configuration of the housing are also design decisions . the design process cannot rationally proceed until these kinds of decisions are made . when the overall design is conceptualized, the design of the individual machine elements in the speed reducer can proceed . you should recognize that you have already made many design decisions by rendering such a sketch . first, you choose spur gears rather than helical gears , a worm and worm gear , or bevel gears. in fact , other types of speed reduction devices –belt drives , chain drives, or many others—could be appreciate.1gearsfor the gear pairs ,you must specify the number of teeth in each gear ,the pitch (size) of the teeth , the pitch diameters, the face width ,and the material and its heat treatment . these specifications depend on considerations of strength and wear of the gear teeth and the motion requirements(kinematics ). You must also recognize that the gears must be mounted on shafts in a manner that ensures proper location of the gears, adequate torque transmitting capability from the gears to the shafts (as through keys ) and safe shaft design.2shaftshaving designed the gear pairs, next you will consider the shaft design . the shaft is loaded in bending and torsion because of the forces acting at the gear teeth . thus, its design must consider strength and rigidity , and it must permit the mounting of the gears and bearings . shafts of varying diameters may be used to provide shoulders against which to seat the gears and bearings. There may be keyseats cut into the shaft, the input and output shafts will extend beyond the housing to permit coupling with the engine and the drive axle . the type of coupling must be considered, as it can have a dramatic effect on the shaft stress analysis. Seals on the input and output shafts protect internal components.3bearingsdesign of the bearings is next. If rolling contact bearings are to be used , you will probably select commercially available bearings from a manufacturer’s catalog , rather than design a unique one . you mustfirst determine the magnitude of the loads on each bearing from the shaft analysis and the gear designs. The rotational speed and reasonable design life of the bearings and their compatibility with the shaft on which they are to be mounted must also be considered. For example , on the basis of the shaft analysis, you could specify the minimum allowable diameter at each bearing seat location to ensure safe stress levels . the bearing selected to support a particular part of the shaft ,then , must have a bore( inside diameter) no smaller than necessary. When a specific bearing is selected , the shaft at the bearing seat location and allowable tolerances must be specified ,according to the bearing manufacturer’s recommendations , to achieve proper operation and life expectancy of the bearing.。
《机械工程专业英语教程》课文翻译
Lesson 1 力学的基本概念1、词汇：statics [stætiks] 静力学；dynamics动力学；constraint约束；magnetic [mæɡ＇netik]有磁性的；external [eks＇tə:nl] 外面的, 外部的；meshing啮合；follower从动件；magnitude [＇mæɡnitju:d] 大小；intensity强度，应力；non-coincident [kəu＇insidənt]不重合；parallel [＇pærəlel]平行；intuitive 直观的；substance物质；proportional [prə＇pɔ:ʃənəl]比例的；resist抵抗，对抗；celestial [si＇lestjəl]天空的；product乘积；particle质点；elastic [i＇læstik]弹性；deformed变形的；strain拉力；uniform全都相同的；velocity[vi＇lɔsiti]速度；scalar[＇skeilə]标量；vector[＇vektə]矢量；displacement代替；momentum [məu＇mentəm]动量；2、词组make up of由……组成；if not要不，不然；even through即使，纵然；Lesson 2 力和力的作用效果1、词汇：machine 机器；mechanism机构；movable活动的；given 规定的，给定的，已知的；perform执行；application 施用；produce引起，导致；stress压力；applied施加的；individual单独的；muscular [＇mʌskjulə]]力臂；gravity[ɡrævti]重力；stretch伸展，拉紧，延伸；tensile[tensail]拉力；tension张力，拉力；squeeze挤；compressive 有压力的，压缩的；torsional扭转的；torque转矩；twist扭，转动；molecule [m likju:l]分子的；slide滑动; 滑行；slip滑，溜；one another 互相；shear剪切；independently独立地，自立地；beam梁；compress压；revolve (使)旋转；exert [iɡ＇zə:t]用力，尽力，运用，发挥，施加；principle原则, 原理，准则，规范；spin使…旋转；screw螺丝钉；thread螺纹；2、词组a number of 许多；deal with 涉及，处理；result from由什么引起；prevent from阻止，防止；tends to 朝某个方向；in combination结合；fly apart飞散；3、译文：任何机器或机构的研究表明每一种机构都是由许多可动的零件组成。
美英报刊阅读教程课件 Lesson15
around the world. In the U.S., one would point his thumb up. A more recent method is to go to websites and arrange lifts beforehand, without soliciting directly from the road.
Lesson 15
1. Makeshift hitchhiking posts sprung up along the curb (Line 2, Para. 6) —路边突然出现了许多临时搭便车 站 (spring up: to suddenly appear or start to exist )
Lesson 15Fra bibliotekLesson 15
The Bronx: The Bronx is New York City’s northernmost borough. It is the only one of the city’s five boroughs situated primarily on the United States mainland rather than on an island. Brooklyn: Brooklyn, named after the Dutch city Breukelen, is New York City’s most populous borough. Brooklyn is characterized by cultural diversity, an independent art scene, distinct neighborhoods, and a unique architectural heritage. Manhattan: As commercial, financial, and cultural center of the city, Manhattan has many famous landmarks, tourist
新概念英语青少版第二册第15课The weighing machine
新概念英语青少版第二册第15课The weighing
machine
Revision Lesson 15 The weighing machine
复习课15 磅秤
Narrator： Sandy and Sue are coming home from school.
桑迪和苏正从学校回家
They meet Professor Boffin.
他们遇见了伯菲教授
Narrator： Professor Boffin is taking his coat off.
伯菲教授正在脱大衣
Sandy： What are you going to do,Professor Boffin?
伯菲教授,您干什么呀
Professor： I'm going to weigh myself,Sandy.
桑迪,我想称称体重
Sue： Where?
在哪里称
Professor： I'm going to weigh myself on this weighing machine.
就在这个磅秤上称
Professor： I'm going to put a penny in the slot.
我要把一便士塞进那个口子
There! (Sandy and Sue laugh.)
进去了 (桑迪和苏笑了起来)
Professor： What's the matter,children?
孩子们,怎么了?
Sue： You're still holding your coat,Professor Boffin! 伯菲教授,您还拿着大衣呢!。
机械工程英语课后习题答案
第一课（第9页） 2.汉翻英1. 机械工业用于制造产品的材料，可以分为金属材料、聚合物、陶瓷和复合材料。
The materials used for manufacturing products can be divided into four categories: metallics, polymerics, ceramics and composites. 2. 金属可以分为有色金属和黑色金属。
Metallics can be classified into non-ferrous and ferrous metallics. 3.塑料可以分为热固性塑料和热塑性塑料。
Plastics cab be grouped into thermosets(thermosetting plastics) and thermoplastics.4. 复合材料可以由两种或两种以上性质不同的材料组合，保留各自的特点，得到单一材料无法比拟的、优越的综合性能。
A composite consists of two more kinds of different materials, with e ach material keeping its own property, to get the superior synthetical (combined) performance which is unparalled (unmatched) by that of the individual material.5. 当其所处的工作环境变化时，智能材料能改变其性能、颜色和形状等。
An intelligent material can change its property, color, shape and so on when its working environment changes.第二课（第17页） 2. 汉翻英1. 材料的特性可分为物理特性和化学特性两大类。
机械类专业英语阅读教程部分翻译
1. Metals and Their UseIt is known that metals are very important in our life. Metals have the greatest importance for industry. All machines and other en gineering constructions have metal parts; some of them consist only of metal parts.There are two large groups of metals:1) Simple metal- more or less pure chemical elements2) Alloys -materials consisting of a simple metal combined with some other elements. About two thirds of all elements found in the earth are metals, but not all metals may be used in industry. Those metals which are used in industry are called engineering metals. The most important engineering metal is iron , which in the form of alloys with carbon and other elements, finds greater use than any other metal. Metals consisting of iron combined with some other elements are known as ferrous metals; all the other metals are called nonferrous metals. The most important nonferrous metal are copper , aluminum ,lead ,zinc ,tin , but all these metals are used much less than ferrous metals, because the ferrous metals are much cheaper. Engineering metals are used in industry in the form of alloys because the properties of alloys are much better than the properties of pure metals. Only aluminum may be largely used in the form of simple metal. Metals have such a great importance because of their useful properties or their strength, hardness, and their plasticity .Different metals are produced in different ways, but almost all the metal are found in the forms of metal ore (iron ore, copper ore, etcet cetra.)The ore is a mineral consistence of a metal combined with some impurities . In order to produce a metal from some metal ore, we must separate these impurities from the metal that is done by metallurgy .2. Plastics and Other MaterialsPlastics have specific properties which may make them preferable to traditional materials for certain uses. In comparison with metals, for example, plastics have both advantages and disadvantages. Metals tend to be corroded by inorganic acids , such as sulphuric acid and hydrochloric acid. Plastics tend to be resistant to these acids, but can have dissolved or deformed by solvent , such as carbon tetrachloride , which have the same carbon base as the plastics. Color must be applied to the surface of metals, whereas it can be mixed in with plastics. Metals are more rigid than most plastics while plastics are very light, with a specific gravity normally between 0.9 and 1.8. Most plastics do not readily conduct heat or electricity . Plastics soften slowly and can easily be shaped when they are soft.塑料具有特殊的性能。
机械工程专业英语(李光布_华中科技大学出版社)课后答案
《机械工程专业英语》翻译李光布饶锡新主编华中科技大学出版社Lesson11 numerical controlIntroductionOne of the most fundamental concepts in the area ……………………数控就是用一个穿孔的纸带或存储的程序来控制机床，美国电子工业协会对数字控制所下的定义为：“一个各项工作都有在各点上直接插入的数字来控制的系统，该系统必须至少能够自动解释这些数字中的部分。
”生产某个零件所需要的数据被称作这个零件程序数控比先前的手工操作生产更多的机械设备，数控机床能够自动的生产不同种类的零件，并且这些零件都有各种各样复杂的加工工艺过程，数字控制使得制造者们可以承担产品的加工，其产品的加工从经济的观点上看使用人工控制机床和加工过程是不太可行的的当一个孔被钻或冲出后，刀具向上撤回快速移动到下一个位置，重复这个步骤，路线沿着一个位置到另一个位置在某一方面是很重要的，他必须挑选一个是经过的时间减少、更有效（的路线）。
点对点的系统主要用于钻床、冲床和连续的铣工序中最近对DNC（现在表示分布式数字控制）的定义涵盖了“使用主计算机作为控制系统，来管理大量的带有机载微型计算机的独立的计算机数控机床”的含义。
这种系统提供了更大的存储和计算机能力来灵活的克服直接数控的缺陷。
计算机数字控制是由控制微型计算机作为机器集成的部分或某种设备一部分的系统（如机载计算机）。
零件程序由编程者事先准备好，该程序应结合由绘图软件包和加工仿真中获得的信息，从而确保零件没有程序缺陷。
机器操控者可以很容易的通过手工对机载计算机进行控制，操作者能够直接对程序进行修改，并为不同的零件制定和存储程序Lesson14 CAMTEXT1.introductionComputer-aided manufacturing involves the use of ……………………计算机辅佐制造的含义是：使用计算机和计算机技术来协助产品制造的所有环节，其中包括加工工艺和生产的辅助设计、加工、生产计划制定、管理和质量控制等！由CAD开发的数据库首先被存储，然后由CAM做进一步的处理，转化为对生产设备和材料处理设备进行操作和控制所必须的数据和命令，对产品的质量进行自动的检测和测试！CAD\CAM的出现对制造业有很大的影响，标准化生产的发展和设计努力、试验和原型工作的减少。
机械工程专业英语教程 (第5版)课件 (14)[10页]
![机械工程专业英语教程 (第5版)课件 (14)[10页]](https://img.taocdn.com/s3/m/8c97c2195acfa1c7ab00cc45.png)
Density The mass per unit volume of a substance under specified conditions of pressure and temperature
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《机械工程专业英语教程》
Pure translation All points on the body describe parallel (rectilinear or curvilinear) paths. A reference line drawn on the body changes its linear position but does not change its angular orientation (see Fig. 15.2) .[5] 5. 物体上所有的点都沿平行（直线或曲线的） 轨迹运动。在物体上所画的一条参考线，只会 改变它的位置，而不会改变它的角度方向。
2021/1/5
《机械工程专业英语教程》
2
• Translation • Motion of a body in which every point of the body moves parallel
to and the same distance as every other point of the body; nonrotational displacement.
• into components along two axes in the plane. [4]
• 4. resolve into 意为“分解为”。全句可译为：在平面或 者二维空间，复杂运动变成了绕一个（垂直于这个平面 的）轴线的转动和同时发生的可以被分解为在这个平面