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1、Unit 1 Introduction to Mechanical Design ContentslNew Words&Expressions lText&TranslationlComplex Sentence AnalysislKey to Exerciseslmechanical design 机械设计lapplication,plikein n.应用，适用ldevise divaiz v.发明，策划loriginal ridnl adj.最初的，独创的lfunction fkn n.功能linnovative inuveitiv adj.创新的lkinematics,kinmtiks
2、n.运动学ldynamics dainmiks n.动力学lmechanical drawing 机械制图New Words&Expressionslmaterials engineering 工程材料lstrength of materials 材料力学lincorporate ink:preit v.合并lfundamental,fndmentl n.基本原则（或原理）lprecision prisin n.精确，精度ldecimal desiml adj.小数的lthrust rst v.用力推ltechnique tekni:k n.技巧，技法lfor the sake of 为了lf
3、lourish fl:ri v.繁荣，茂盛，活跃New Words&Expressionslultimately ltimitli adv.最后，终于lpsychologist saikldist n.心理学家loptimum ptimm adj.最理想的laccomplishment kmplimnt n.成就，完成lgraphical grfikl adj.图解的lversatile v:stail adj.多功能的，多才多艺的lhandicap hndikp v.妨碍，使不利laffirmative f:mtiv adj.肯定的，表示赞成的lassembly sembli n.装配lma
4、nufacturing cycle 制造周期New Words&ExpressionsText&TranslationlMechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs.1It is a vast field of engineering technology which not only concerns itself with the original conce
5、ption of the product in terms of its size,shape and construction details,but also considers the various factors involved in the manufacture,marketing and use of the product.Text&TranslationlPeople who perform the various functions of mechanical design are typically called designers,or design enginee
6、rs.Mechanical design is basically a creative activity.However,in addition to being innovative,a design engineer must also have a solid background in the areas of mechanical drawing,kinematics,dynamics,materials engineering,strength of materials and manufacturing processes.Text&TranslationlAs stated
7、previously,the purpose of mechanical design is to produce a product which will serve a need for man.Inventions,discoveries and scientific knowledge by themselves do not necessarily benefit people;only if they are incorporated into a designed product will a benefit be derived.It should be recognized,
8、therefore,that a human need must be identified before a particular product is designed.Text&TranslationlMechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product,to analyze the system and then make sound judgments on how the product is to
9、 be manufactured.It is important to understand the fundamentals of engineering rather than memorize mere facts and equations.There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design.On the other hand,any calculations made must be
10、done with the utmost care and precision.For example,if a decimal point is misplaced,an otherwise acceptable design may not function.Text&TranslationlGood designs require trying new ideas and being willing to take a certain amount of risk,knowing that if the new idea does not work the existing method
11、 can be reinstated.Thus a designer must have patience,since there is no assurance of success for the time and effort expended.Creating a completely new design generally requires that many old and well-established methods be thrust aside.This is not easy since many people cling to familiar ideas,tech
12、niques and attitudes.A design engineer should constantly search for ways to improve an existing product and must decide what old,proven concepts should be used and what new,untried ideas should be incorporated.Text&TranslationlNew designs generally have“bugs”or unforeseen problems which must be work
13、ed out before the superior characteristics of the new designs can be enjoyed.Thus there is a chance for a superior product,but only at higher risk.2 It should be emphasized that,if a design does not warrant radical new methods,such methods should not be applied merely for the sake of change.Text&Tra
14、nslationlDuring the beginning stages of design,creativity should be allowed to flourish without a great number of constraints.Even though many impractical ideas may arise,it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing.In this way,
15、innovative ideas are not inhibited.Quite often,more than one design is developed,up to the point where they can be compared against each other,it is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall
16、 promise.Text&TranslationlPsychologists frequently talk about trying to fit people to the machines they operate.It is essentially the responsibility of the design engineer to strive to fit machines to people.This is not an easy task,since there is really no average person for which certain operating
17、 dimensions and procedures are optimum.Text&TranslationlAnother important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated.Communicating the design to others is the final,vital step in the design process.Undou
18、btedly many great designs,inventions,and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others.Presentation is a selling job.The engineer,when presenting a new solution to administrative,management,or supervisory p
19、ersons,is attempting to sell or to prove to them that this solution is a better one.Unless this can be done successfully,the time and effort spent on obtaining the solution have been largely wasted.Text&TranslationlBasically,there are only three means of communication available to us.These are the w
20、ritten,the oral,and the graphical forms.Therefore the successful engineer will be technically competent and versatile in all three forms of communication.A technically competent person who lacks ability in any one of these forms is severely handicapped.If ability in all three forms is lacking,no one
21、 will ever know how competent that person is!Text&TranslationlThe competent engineer should not be afraid of the possibility of not succeeding in a presentation.In fact,occasional failure should be expected because failure or criticism seems to accompany every really creative idea.There is a great d
22、eal to be learned from a failure,and the greatest gains are obtained by those willing to risk defeat.3In the final analysis,the real failure would lie in deciding not to make the presentation at all.To communicate effectively,the following questions must be answered:Text&Translationl(1)Does the desi
23、gn really serve a human need?l(2)Will it be competitive with existing products of rival companies?l(3)Is it economical to produce?l(4)Can it be readily maintained?l(5)Will it sell and make a profit?Text&TranslationlOnly time will provide the true answers to the preceding questions,but the product sh
24、ould be designed,manufactured and marketed only with initial affirmative answers.The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings.Text&TranslationlQuite often,a problem will occur during the manufacturing cycle.It may be
25、that a change is required in the dimensioning or tolerancing of a part so that it can be more readily produced.4This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected.In other cases,a deficiency in t
26、he design may appear during assembly or testing just prior to shipping.These realities simply bear out the fact that design is a living process.There is always a better way to do it and the designer should constantly strive towards finding that better way.Text&Translationl机械设计是一门通过设计新产品或者改进老产品满足人类需求
27、的应用技术科学。它涉及工程技术的各个领域，主要研究产品的尺寸、形状和具体结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。l进行各种机械设计工作的人员通常被称为设计人员或者设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创新性，还必须在机械制图、运动学、动力学、工程材料、材料力学和机械制造工艺等方面具有扎实的基础知识。Text&Translationl如前面所述，机械设计的目的是生产满足人类需求的产品。发明、发现和科学知识本身并不一定能给人类带来益处，只有当它们被用在产品上才能产生效益。因而，应该认识到在一个特定产品进行设计之前，必须先确定人们是否需要这种产品。l应
28、当把机械设计看成设计人员运用创造性的才能进行产品设计、系统分析和制订产品的制造工艺的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确地进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。Text&Translationl好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险；当新的方法不适用时，就重新采用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求摒弃许多陈旧的，为人们所熟知的方法。由于许多人易于墨守成规，这样做并不
29、是一件容易的事情。一位设计工程师应该不断地探索改进现有产品的办法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。Text&Translationl新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。l在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切合实际的想法，也会在设计的早期，即绘制生产图纸之前被改正。只有这样，才不至于堵塞创新
30、的思路。通常要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。Text&Translationl心理学家经常讨论如何使人们适应他们所操作的机器。设计人员的基本职能是努力使机器来适应人们。这并不是一项容易的工作，因为实际上并不存在着一个对所有人来说都是最优的操作范围和操作过程。l另一个应该被认识到的重要问题是，设计工程师必须能够同其他有关人员进行交流和沟通。与其他人就设计方案进行交流和沟通是实际过程的最后和关键阶段。毫无疑问，有许多伟大的设计、发明或创造之所以没有为人类所利用，就是因为创造者不善于或者不愿意向他人介绍自己的成果。提出方案是一种说服
31、别人的工作。当一个工程师向经营、管理部门或者其主管人员提出自己的新方案时，就是希望向他们说明或者证明自己的方案是比较好的。只有成功地完成这项工作，为得出这个方案所花费的大量时间和精力才不会被浪费掉。Text&Translationl人们基本上只有三种表达自己思想的方式，即文字材料、口头表述和绘图。因此，一个优秀的工程师除了掌握技术之外，还应该精通这三种表达方式。如果一个技术能力很强的人在上述三种表达方式中的某一种的能力较差，他就会遇到很大的困难。如果上述三种能力都较差，那将永远没有人知道他是一个多么能干的人！l一个有能力的工程师不应该害怕在提出自己的方案时遭到失败的可能性。事实上，偶然的失败肯
32、定会发生的，因为每个真正有创造性的设想似乎总是有失败或者伴随着它。从一次失败中可以学到很多东西，只有不怕遭受失败的人们才能取得最大的收获。总之，决定不把方案提交出来，才是真正的失败。Text&Translationl为了进行有效的交流，需要解决下列问题：l（1）所要设计的这个产品是否真正为人们所需要？l（2）此产品与其他公司的现有同类产品相比有无竞争能力？l（3）生产这种产品是否经济？l（4）产品的维修是否方便？l（5）产品有无销路？是否可以盈利？Text&Translationl只有时间才能对上述问题给出正确的答案。但是，产品的设计、制造和销售只能在对上述问题的初步肯定答案的基础上进行。设计
33、工程师还应该通过零件图和装配图，与制造部门一起对最终设计方案进行沟通。l通常，在制造过程中会出现某个问题。，可能要求对某个零件尺寸或公差做一些更改，使零件的生产变得容易。但是，工程上的更改必须经过设计人员批准，以保证不会损伤产品的功能。有时，在产品的装配时或者装箱外运前的实验中才发现设计中的某种缺陷。这些事例恰好说明了设计是一个动态过程。总是存在着更好的方法来完成设计工作，设计人员应该不断努力，寻找这些更好的方法。Complex Sentence Analysisl1 It is a vast field of engineering technology which not only con
34、cerns itself with the original conception of the product in terms of its size,shape and construction details,but also considers the various factors involved in the manufacture,marketing and use of the product.它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。lwhich not only concerns itself w
35、ith the original conception of the product in terms of its size,shape and construction details,but also considers the various factors involved in the manufacture,marketing and use of the product.这是一个由which 引导的限制性定语从句，其先行词为field。其中not only，but also引导的是并列的两个部分。l in terms of 是“根据、按照”的意思。Complex Sentenc
36、e Analysisl2 It should be emphasized that,if a design does not warrant radical new methods,such methods should not be applied merely for the sake of change.应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。lmerely for the sake of 是“仅仅为了”的意思。Complex Sentence Analysisl3In the final analysis,the real failur
37、e would lie in deciding not to make the presentation at all.总之，决定不把方案提交出来，才是真正的失败。lIn the final analysis 是“总之，归根结底”的意思。llie in:存在于。Complex Sentence Analysisl4This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adver
38、sely affected.但是，工程上的更改必须经过设计人员批准，以保证不会损伤产品的功能。lfall in the category of:属于哪一类lwhich must be approved by the design engineer so that the product function will not be adversely affected这是一个限制性定语从句，其先行词为engineering changes。Key to Exercisesl.Translate the following phrases into Chinese or English.l1.机械设
39、计l2.mechanical drawingl3.动力学l4.materials engineeringl5.材料力学l6.take a certain amount of riskl7.未能预料的问题l8.merely for the sake of l9.操作范围 l10.manufacturing cycle Key to Exercisesl.Mark the following statement with True(T)or False(F)according to the text.l1Fl2Tl3Fl4Fl5TKey to Exercisesl.Fill in the blan
40、ks with the suitable words or phrases given below.l1.occurl2.dimensioningl3.categoryl4.adverselyl5.prior to shippingl6.strivel.Translate the Chinese parts given in the brackets into English.l1.for the purpose of satisfying human needsl2.who perform the various functions of mechanical designl3.understand the fundamentals of engineeringl4.have“bugs”or unforeseen problemsl5.through the use of detail and assembly drawingslThe end!