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1、<p><b>  機械設(shè)計理論</b></p><p>  機械設(shè)計是一門通過設(shè)計新產(chǎn)品或者改進(jìn)老產(chǎn)品來滿足人類需求的應(yīng)用技術(shù)科學(xué)。它涉及工程技術(shù)的各個領(lǐng)域,主要研究產(chǎn)品的尺寸、形狀和詳細(xì)結(jié)構(gòu)的基本構(gòu)思,還要研究產(chǎn)品在制造、銷售和使用等方面的問題。</p><p>  進(jìn)行各種機械設(shè)計工作的人員通常被稱為設(shè)計人員或者機械設(shè)計工程師。機械設(shè)計是一項創(chuàng)造性的工

2、作。設(shè)計工程師不僅在工作上要有創(chuàng)造性,還必須在機械制圖、運動學(xué)、工程材料、材料力學(xué)和機械制造工藝學(xué)等方面具有深厚的基礎(chǔ)知識。 </p><p>  如前所訴,機械設(shè)計的目的是生產(chǎn)能夠滿足人類需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科技知識本身并不一定能給人類帶來好處,只有當(dāng)它們被應(yīng)用在產(chǎn)品上才能產(chǎn)生效益。因而,應(yīng)該認(rèn)識到在一個特定的產(chǎn)品進(jìn)行設(shè)計之前,必須先確定人們是否需要這種產(chǎn)品。</p><p>  應(yīng)

3、當(dāng)把機械設(shè)計看成是機械設(shè)計人員運用創(chuàng)造性的才能進(jìn)行產(chǎn)品設(shè)計、系統(tǒng)分析和制定產(chǎn)品的制造工藝學(xué)的一個良機。掌握工程基礎(chǔ)知識要比熟記一些數(shù)據(jù)和公式更為重要。僅僅使用數(shù)據(jù)和公式是不足以在一個好的設(shè)計中做出所需的全部決定的。另一方面,應(yīng)該認(rèn)真精確的進(jìn)行所有運算。例如,即使將一個小數(shù)點的位置放錯,也會使正確的設(shè)計變成錯誤的。</p><p>  一個好的設(shè)計人員應(yīng)該勇于提出新的想法,而且愿意承擔(dān)一定的風(fēng)險,當(dāng)新的方法不適用時

4、,就使用原來的方法。因此,設(shè)計人員必須要有耐心,因為 所花費的時間和努力并不能保證帶來成功。一個全新的設(shè)計,要求屏棄許多陳舊的,為人們所熟知的方法。由于許多人墨守成規(guī),這樣做并不是一件容易的事。一位機械設(shè)計師應(yīng)該不斷地探索改進(jìn)現(xiàn)有的產(chǎn)品的方法,在此過程中應(yīng)該認(rèn)真選擇原有的、經(jīng)過驗證的設(shè)計原理,將其與未經(jīng)過驗證的新觀念結(jié)合起來。</p><p>  新設(shè)計本身會有許多缺陷和未能預(yù)料的問題發(fā)生,只有當(dāng)這些缺陷和問題被

5、解決之后,才能體現(xiàn)出新產(chǎn)品的優(yōu)越性。因此,一個性能優(yōu)越的產(chǎn)品誕生的同時,也伴隨著較高的風(fēng)險。應(yīng)該強調(diào)的是,如果設(shè)計本身不要求采用全新的方法,就沒有必要僅僅為了變革的目的而采用新方法。</p><p>  在設(shè)計的初始階段,應(yīng)該允許設(shè)計人員充分發(fā)揮創(chuàng)造性,不受各種約束。即使產(chǎn)生了許多不切實際的想法,也會在設(shè)計的早期,即繪制圖紙之前被改正掉。只有這樣,才不致于堵塞創(chuàng)新的思路。通常,要提出幾套設(shè)計方案,然后加以比較。很

6、有可能在最后選定的方案中,采用了某些未被接受的方案中的一些想法。 </p><p>  心理學(xué)家經(jīng)常談?wù)撊绾问谷藗冞m應(yīng)他們所操作的機器。設(shè)計人員的基本職責(zé)是努力使機器來適應(yīng)人們。這并不是一項容易的工作,因為實際上并不存在著一個對所有人來說都是最優(yōu)的操作范圍和操作過程。</p><p>  另一個重要問題,設(shè)計工程師必須能夠同其他有關(guān)人員進(jìn)行交流和磋商。在開始階段,設(shè)計人員必須就初步設(shè)計同管

7、理人員進(jìn)行交流和磋商,并得到批準(zhǔn)。這一般是通過口頭討論,草圖和文字材料進(jìn)行的。為了進(jìn)行有效的交流 ,需要解決下列問題:</p><p> ?。?) 所設(shè)計的這個產(chǎn)品是否真正為人們所需要?</p><p> ?。?) 此產(chǎn)品與其他公司的現(xiàn)有同類產(chǎn)品相比有無競爭能力?</p><p> ?。?) 生產(chǎn)這種產(chǎn)品是否經(jīng)濟(jì)?</p><p>  (4

8、) 產(chǎn)品的維修是否方便?</p><p>  (5) 產(chǎn)品有無銷路?是否可以盈利? </p><p>  只有時間能對上述問題給出正確答案。但是, 產(chǎn)品的設(shè)計、制造和銷售只能在對上述問題的初步肯定答案的基礎(chǔ)上進(jìn)行。設(shè)計工程師還應(yīng)該通過零件圖和裝配圖,與制造部門一起對最終設(shè)計方案進(jìn)行磋商。</p><p>  通常 ,在制造過程中會出現(xiàn)某個問題。可能會要求對某個零件尺

9、寸或公差作一些更改,使零件的生產(chǎn)變得容易。但是,工程上的更改必須要經(jīng)過設(shè)計人員批準(zhǔn),以保證不會損傷產(chǎn)品的功能。有時,在產(chǎn)品的裝配時或者裝箱外運前的試驗中才發(fā)現(xiàn)設(shè)計中的某種缺陷。這些事例恰好說明了設(shè)計是一個動態(tài)過程??偸谴嬖谥玫姆椒▉硗瓿稍O(shè)計工作,設(shè)計人員應(yīng)該不斷努力,尋找這些更好的方法。</p><p>  近些年來,工程材料的選擇已經(jīng)顯得重要。此外,選擇過程應(yīng)該是一個對材料的連續(xù)不斷的重新評價過程。新材料不

10、斷出現(xiàn),而一些原有的材料的能夠獲得的數(shù)量可能會減少。環(huán)境污染、材料的回收利用、工人的健康及安全等方面經(jīng)常會對材料選擇附加新的限制條件。為了減輕重量或者節(jié)約能源,可能會要求使用不同的材料。來自國內(nèi)和國際競爭、對產(chǎn)品維修保養(yǎng)方便性要求的提高和顧客的反饋等方面的壓力,都會促使人們對材料進(jìn)行重新評價。由于材料選用不當(dāng)造成的產(chǎn)品責(zé)任訴訟,已經(jīng)產(chǎn)生了深刻的影響。此外,材料與材料加工之間的相互依賴關(guān)系已經(jīng)被人們認(rèn)識得更清楚。因此,為了能在合理的成本和

11、確保質(zhì)量的前提下獲得滿意的結(jié)果,設(shè)計工程師的制造工程師都必須認(rèn)真仔細(xì)地選擇、確定和使用材料。</p><p>  制造任何產(chǎn)品的第一步工作都是設(shè)計。設(shè)計通??梢苑譃閹讉€明確的階段:(a)初步設(shè)計;(b)功能設(shè)計;(c)生產(chǎn)設(shè)計。在初步設(shè)計階段,設(shè)計者著重考慮產(chǎn)品應(yīng)該具有的功能。通常要設(shè)想和考慮幾個方案,然后決定這種思想是否可行;如果可行,則應(yīng)該對其中一個或幾個方案作進(jìn)一步的改進(jìn)。在此階段,關(guān)于材料選擇唯一要考慮的

12、問題是:是否有性能符合要求的材料可供選擇;如果沒有的話,是否有較大的把握在成本和時間都允許的限度內(nèi)研制出一種新材料。</p><p>  在功能設(shè)計和工程設(shè)計階段,要做出一個切實可行的設(shè)計。在這個階段要繪制出相當(dāng)完整的圖紙,選擇并確定各種零件的材料。通常要制造出樣機或者實物模型,并對其進(jìn)行試驗,評價產(chǎn)品的功能、可靠性、外觀和維修保養(yǎng)性等。雖然這種試驗可能會表明,在產(chǎn)品進(jìn)入到生產(chǎn)階段之前,應(yīng)該更換某些材料,但是,絕

13、對不能將這一點作為不認(rèn)真選擇材料的借口。應(yīng)該結(jié)合產(chǎn)品的功能,認(rèn)真仔細(xì)地考慮產(chǎn)品的外觀、成本和可靠性。一個很有成就的公司在制造所有的樣機時,所選用的材料應(yīng)該和其生產(chǎn)中使用的材料相同,并盡可能使用同樣的制造技術(shù)。這樣對公司是很有好處的。功能完備的樣機如果不能根據(jù)預(yù)期的銷售量經(jīng)濟(jì)地制造出來,或者是樣機與正式生產(chǎn)的裝置在質(zhì)量和可靠性方面有很大不同,則這種樣機就沒有多大的價值。設(shè)計工程師最好能在這一階段完全完成材料的分析、選擇和確定工作,而不是將

14、其留到生產(chǎn)設(shè)計階段去做。因為,在生產(chǎn)設(shè)計階段材料的更換是由其他人進(jìn)行的,這些人對產(chǎn)品的所有功能的了解不如設(shè)計工程師。 </p><p>  在生產(chǎn)設(shè)計階段中,與材料有關(guān)的主要問題是應(yīng)該把材料完全確定下來,使它們與現(xiàn)有的設(shè)備相適應(yīng),能夠利用現(xiàn)有設(shè)備經(jīng)濟(jì)地進(jìn)行加工,而且材料的數(shù)量能夠比較容易保證供應(yīng)。</p><p>  在制造過程中,不可避免地會出現(xiàn)對使用中的材料做一些更改的情況。經(jīng)驗表明,

15、可采用某些便宜材料作為替代品。然而,在大多數(shù)情況下,在進(jìn)行生產(chǎn)以后改換材料要比在開始生產(chǎn)前改換材料所花費的代價要高。在設(shè)計階段做好材料選擇工作,可以避免多數(shù)這樣的情況。在生產(chǎn)制造開始后出現(xiàn)了可供使用的新材料是更換材料的最常見的原因。當(dāng)然,這些新材料可能降低成本、改進(jìn)產(chǎn)品的性能。但是,必須對新材料進(jìn)行認(rèn)真的評價,以確保其所有性能都滿足要求。應(yīng)當(dāng)記住,新材料的性能和可靠性很少像現(xiàn)有材料那樣為人們所了解。大部分的產(chǎn)品失效和產(chǎn)品責(zé)任事故案件是由

16、于在選用新材料作為替代材料之前,沒有真正了解它們的長期使用性能而引起的。</p><p>  產(chǎn)品的責(zé)任訴訟迫使設(shè)計人員和公司在選擇材料時,采用最好的程序。在材料過程中,五個最常見的問題為:(a)不了解或者不會使用關(guān)于材料應(yīng)用方面的最新最好的信息資料;(b)未能預(yù)見和考慮擦黑年品可能的合理用途(如有可能,設(shè)計人員還應(yīng)進(jìn)一步預(yù)測和考慮由于產(chǎn)品使用方法不當(dāng)造成的后果。在近年來的許多產(chǎn)品責(zé)任訴訟案件中,由于錯誤地使用產(chǎn)

17、品而受到傷害的原告控告生產(chǎn)廠家,并且贏得判決);(c)所使用的材料的數(shù)據(jù)不全或是有些數(shù)據(jù)不確定,尤其是當(dāng)其長期性能數(shù)據(jù)是如此的時候;(d)質(zhì)量控制方法不適當(dāng)和未經(jīng)驗證;(e)由一些完全不稱職的人員選擇材料。</p><p>  通過對上述五個問題的分析,可以得出這些問題是沒有充分理由存在的結(jié)論。對這些問題的研究分析可以為避免這些問題的出現(xiàn)指明方向。盡管采用最好的材料選擇方法也不能避免發(fā)生產(chǎn)品責(zé)任訴訟,設(shè)計人員和工

18、業(yè)界按照適當(dāng)?shù)某绦蜻M(jìn)行材料選擇,可以大大減少訴訟的數(shù)量。</p><p>  從以上的討論可以看出,選擇材料的人們應(yīng)該對材料的性質(zhì),特點和加工方法有一個全面而基本的了解。</p><p>  Machine design theory </p><p>  The machine design is through designs the new product o

19、r improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, b

20、ut also must study the product the personnel which in aspect the and so on manufacture, sale and use question.</p><p>  Carries on each kind of machine design work to be usually called designs the personnel

21、or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, ma

22、terials mechanics and machine manufacture technology has the deep elementary knowledge. </p><p>  If front sues, the machine design goal is the production can meet the human need the product. The invention,

23、the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on be

24、fore the design in a specific product, must first determine whether the people do need this kind of product</p><p>  Must regard as the machine design is the machine design personnel carries on using creativ

25、e ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important

26、 than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all op</p><p>  A good

27、design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have

28、the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because m

29、any person of conservativeness, does this certainly i</p><p>  Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the quest

30、ion are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itsel

31、f does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method. </p><p>  In the design preliminary stage, should allow to design the personnel f

32、ully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not sen

33、d to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used cer</p>

34、<p>  How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people.

35、 This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process. </p><p>  Another important question, proj

36、ect engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary

37、 design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to

38、solve the following problem:</p><p>  (1) designs whether this product truly does need for the people? Whether there is competitive ability </p><p>  (2) does this product compare with other com

39、panies'' existing similar products? </p><p>  (3) produces this kind of product is whether economical? </p><p>  (4) product service is whether convenient? </p><p>  (5) pro

40、duct whether there is sale? Whether may gain?</p><p>  Only has the time to be able to produce the correct answer to above question. But, the product design, the manufacture and the sale only can in carry on

41、 to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of manufacture t

42、o the finally design proposal.</p><p>  Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the compone

43、nts the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembl

44、y or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instan</p><p>  Recent year, the engineerig material choice already appeared importantly. In additio

45、n, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The envir

46、onmental pollution, material recycling aspect and so on use, worker''s health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight</p><

47、p>  Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design sta

48、ge, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the fu

49、rther improvement to or several plans. In this stage, the question </p><p>  In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite compl

50、ete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the rel

51、iability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product </p><p>  n the production design stage, is should comple

52、tely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantit

53、y can quite be easy to guarantee the supply. </p><p>  In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certai

54、n cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material

55、will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situati</p><p>  The product responsibility lawsuit forces designs the personnel and t

56、he company when the choice material, uses the best procedure. In the material process, five most common questions are: (a) did not understand or cannot use about the material application aspect most newly the best inform

57、ation paper; (b) has not been able to foresee and to consider the dusk year possible reasonable use (for example to have the possibility, designs the personnel also to be supposed further to forecast and the con</p>

58、;<p>  Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses t

59、he appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of

60、material according to the suitable procedure, may greatly reduce the lawsu</p><p>  May see from the above discussion, the choice material people should to the material nature, the characteristic and the pro

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