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湖 南 科 技 大 學
英文文獻翻譯
學 生 姓 名: 劉志強
學 院: 機電工程學院
專業(yè)及班級: 機設(shè)3班
學 號: 1103010321
指 導 教 師: 胡忠舉
2015 年 5 月 30 日
Mechanical?Design
Abstract:
A?machine?is?a?combination?of?mechanisms?and?other?components?whic transforms,?transmits.?Examples?are?engines,?turbines,?vehicles,?hoists,?printing presses,?washing?machines,?and?movie?cameras.?Many?of?the?principles?andmethods of?design?that?apply?to?machines?also?apply?to?manufactured?articles?that?are?not?true?machines.?The?term?"mechanical?design"?is?used?in?a?broader?sense?than?"machine design"?to?include?their?design.?the?motion?and?structural?aspects?and?the?provisions? or?retention?and?enclosure?are?considerations?in?mechanical?design.?Applications occur?in?the?field?of?mechanical?engineering,?and?in?other?engineering?fields?as?well, all?of?which?require?mechanical?devices,?such?as?switches,?cams,?valves,?vessels,?and?mixers.
Keywords:?Mechanical?Design?mechanisms?Design?Process
The?Design?Process
Designing?starts?with?a?need?real.Existing?apparatus?may?need?improvements?in durability,?efficiency,?weight,?speed,?or?cost.?New?apparatus?may?be?needed?to perform?a?function?previously
done?by?men,?such?as?computation,?assembly,?or?servicing.?With?the?objective wholly?or?partly
In?the?design?preliminary?stage,?should?allow?to?design?the?personnel?fully?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?send?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?certain?not?in?plan?some?ideas?which?accepts.
When?the?general?shape?and?a?few?dimensions?of?the?several?components?become? apparent,?analysis?can?begin?in?earnest.?The?analysis?will?have?as?its?objective satisfactory?or?superior?performance,?plus?safety?and?durability?with?minimum?weight,?and?a?competitive?cost.?Optimum?proportions?and?dimensions?will?be?sought?for?each?critically?loaded?section,?together?with?a?balance?between?the?strengths?of?the?several components.?Materials?and?their?treatment?will?be?chosen.?These?important?objectives?can?be?attained?only?by?analysis?based?upon?the?principles?of?mechanics,?such?as?those?of?static?for?reaction?forces?and?for?the?optimum?utilization?of?friction;?of?dynamics for?inertia,?acceleration,?and?energy;?of?elasticity?and?strength?of?materials?for?stress and?deflection;?of?physical?behaviorof?materials;?and?of?fluid?mechanics?for lubrication?and?hydrodynamic?drives.?The?analyses?may?be?made?by?the?same engineer?who?conceived?the?arrangement?of?mechanisms,?or,?in?a?large?company,?they?may?be?made?by?a?separate?analysis?division?or?research?group.?Design?is?a?reiterative?and?cooperative?process,?whether?done?formally?or?informally,?and?the?analyst?can contribute?to?phases?other?than?his?own.?Product?design?requires?much?research?and development.?Many?Concepts?of?an?idea?must?be?studied,?tried,?and?then?either?used or?discarded.?Although?the?content?of?each?engineering?problem?is?unique,?the designers?follow?the?similar?process?to?solve?the?problems.
Product?liability?suits?designers?and?forced?in?material?selection,?using?the?best?program.?In?the?process?of?material,?the?most?common?problems?for?five?(a)?don't understand or?not?use?about?the?latest?application materials?to?the?best information,?(b)?failed?to?foresee?and?consider?the?reasonable?use?material?may?(such as?possible,?designers?should?further?forecast?and?consider?due?to?improper?use?products.?In?recent?years,?many?products?liability?in?litigation,?the?use?of products?and?hurt?the?plaintiff?accused?manufacturer,?and?won?the?decision),?(c)?of?the?materials?used?all?or?some?of?the?data,?data,?especially?when?the?uncertainty?long-term?performance?data?is?so,?(d)?quality?control?method?is?not?suitable?and?unproven,?(e) by?some?completely?incompetent?persons?choose?materials.?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?the?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?material?according?to the?suitable?procedure,?may?greatly?reduce?the?lawsuit?the?quantity.
May?see?from?the?above?discussion,?the?choice?material?people?should?to?the material?nature,?the?characteristic?and?the?processing?method?have?comprehensive?and?the?basic?understanding.
Finally,?a?design?based?upon?function,?and?a?prototype?may?be?built.?If?its?tests?are satisfactory,?the?initial?design?will?undergo?certain?modifications?that?enable?it?to?be manufactured?in?quantity?at?a?lower?cost.?During?subsequent?years?of?manufacture?and?service,?the?design?is?likely?to?undergo?changes?as?new?ideas?are?conceived?or?as further?analyses?based?upon?tests?and?experience?indicate?alterations.?Sales?appeal.
Some?Rules?for?Design
In?this?section?it?is?suggested?that,?applied?with?a?creative?attitude,?analyses?can?leadto?important?improvements?and?to?the?conception?and?perfection?of?alternate,?perhaps?more?functional,?economical,?and?durable?products.
To?stimulate?creative?thought,?the?following?rules?are?suggested?for?the designer?and?analyst.?The?first?six?rules?are?particularly?applicable?for?the?analyst.
1.?A?creative?use?of?need?of?physical?properties?and?control?process.
2.?Recognize?functional?loads?and?their?significance.?3.?Anticipate?unintentional loads.
4.?Devise?more?favorable?loading?conditions.
5.?Provide?for?favorable?stress?distribution?and?stiffness?with?minimum?weight.
6.Use?basic?equations?to?proportion?and?optimize?dimensions.
7.?Choose?materials?for?a?combination?of?properties.
8.?Select?carefully,?stock?and?integral?components.
9.?Modify?a?functional?design?to?fit?the?manufacturing?process?and?reduce?cost.
10.?Provide?for?accurate?location?and?noninterference?of?parts?in?assembly.? Machinery?design?covers?the?following?contents.
1.?Provides?an?introduction?to?the?design?process?,?problem?formulation?,safety factors.
2.?Reviews?the?material?properties?and?static?and?dynamic?loading?analysis, ?Including?beam?,?vibration?and?impact?loading.
3.?Reviews?the?fundamentals?of?stress?and?defection?analysis.
4.?Introduces?fatigue-failure?theory?with?the?emphasis?on?stress-life
approaches?to?high-cycle?fatigue?design,?which?is?commonly?used?in?the?design?of ?rotation?machinery.
5.?Discusses?thoroughly?the?phenomena?of?wear?mechanisms,?surface?contact? stresses?,and?surface?fatigue.
6.?Investigates?shaft?design?using?the?fatigue-analysis?techniques.
7.?Discusses?fluid-film?and?rolling-element?bearing?theory?and?application
8.?Gives?a?thorough?introduction?to?the?kinematics,?design?and?stress?analysis?of spur?gears?,?and?a?simple?introduction?to?helical?,bevel?,and?worm?gearing.
9.?Discusses?spring?design?including?compression?,extension?and?torsion?springs.
10.?Deals?with?screws?and?fasteners?including?power?screw?and?preload?fasteners.
11.?Introduces?the?design?and?specification?of?disk?and?drum?clutches?and?brakes.
Machine?Design
The?complete?design?of?a?machine?is?a?complex?process.?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,?materials?mechanics?and?machine?manufacture?technology?has?the?deep?elementary? knowledge.
One?of?the?first?steps?in?the?design?of?any?product?is?to?select?the?material?from? which?each?part?is?to?be?made.?Numerous?materials?are?available?to?today's?designers.?The?function?of?the?product,?its?appearance,?the?cost?of?the?material,?and?the?cost?of? fabrication?are?important?in?making?a?selection.?A?careful
evaluation?of?the?properties?of?a.?material?must?be?made?prior?to?any?calculations.??Careful?calculations?are?necessary?to?ensure?the?validity?of?a?design.?In?case?of?any? part?failures,?it?is?desirable?to?know?what?was?done?in?originally?designing?the?defective?components.?The?checking?of?calculations?(and?drawing?dimensions)is?of?utmost?importance.The?misplacement?of?one?decimal?point?can?ruin?an?otherwise?acceptable project.All?aspects?of?design?work?should?be?checked?and?rechecked.? The?computer?is?a?tool?helpful?to?mechanical?designers?to?lighten?tedious?calculations,?and?provideextended?analysis?of?available?data.?Interactive?systems,?based?on?computer?capabilities,?have?made?possible?the?concepts?of?computer?aided?design?(CAD)?and?computer-aided?manufacturing?(CAM).?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.?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.?Another?important question,?project?engineer?must?be?able?to?carry?on?the?exchange?and?the?consultation?withother?concerned?personnel.?In?the?initial?stage,?designs?the?personnel?to?have?to?carry?on?the?exchange?and?the?consultation?on?the?preliminary?design?with?the?administrative personnel,?and?is?approved.?This?generally?is?through?the?oral?discussion,?the schematic?diagram?and?the?writing?material?carries?on.
If?front?sues,?the?machine?design?goal?is?the?production?can?meet?the?human?need the?product.?The?invention,?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?before?the design?in?a?specific?product,?must?first?determine?whether?the?people?do?need?this?kind?of?product
Must?regard?as?the?machine?design?is?the?machine?design?personnel?carries?on?using?creative?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?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 operations.?For?example,?even?if?places?wrong?a?decimal?point?position,?also?can?cause?the?correct?design?to?turn?wrongly.
A?good?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?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?many?person?of?conservativeness, does?this?certainly?is?not?an?easy?matter.?A?mechanical?designer?should?unceasingly explore?the?improvement?existing?product?the
method,?should?earnestly?choose?originally,?the?process?confirmation?principle?of design?in?this?process,?with?has?not?unified?it?after?the?confirmation?new?idea.
機械設(shè)計?
摘要:?機器是由機械裝置和其它組件組成的。它是一種用來轉(zhuǎn)換或傳遞能量的裝置,例如:發(fā)動機、渦輪機、車輛、起重機、印刷機、洗衣機、照相機和攝影機等。許多原則和設(shè)計方法不但適用于機器的設(shè)計,也適用于非機器的設(shè)計。術(shù)語中的“機械裝置設(shè)計”?的含義要比“機械設(shè)計”的含義更為廣泛一些,機械裝置設(shè)計包括機械設(shè)計。在分析運動及設(shè)計結(jié)構(gòu)時,要把產(chǎn)品外型以及以后的保養(yǎng)也要考慮在機械設(shè)計中。在機械工程領(lǐng)域中,以及其它工程領(lǐng)域中,所有這些都需要機械設(shè)備,比如:開關(guān)、凸輪、閥門、船舶以及攪拌機等。
?關(guān)鍵詞:?設(shè)計流程??設(shè)計規(guī)則??機械設(shè)計??
設(shè)計流程?
設(shè)計開始之前就要想到機器的實際性,現(xiàn)存的機器需要在耐用性、效率、重量、速度,或者成本上得到改善。新的機器必需具有以前機器所能執(zhí)行的功能。?
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,不要受到任何約束。即使產(chǎn)生了許多不切實際的想法,也會在設(shè)計的早期,即在繪制圖紙之前被改正掉。只有這樣,才不致于阻斷創(chuàng)新的思路。通常,還要提出幾套設(shè)計方案,然后加以比較。很有可能在這個計劃最后決定中,使用了某些不在計劃之內(nèi)的一些設(shè)想。?
一般的當外型特點和組件部分的尺寸特點分析得透徹時,就可以全面的設(shè)計和分析。接著還要客觀的分析機器性能的優(yōu)越性,以及它的安全、重量、耐用性,并且競爭力的成本也要考慮在分析結(jié)果之內(nèi)。每一個至關(guān)重要的部分要優(yōu)化它的比例和尺寸,同時也要保持與其它組成部分相協(xié)調(diào)。?
也要選擇原材料和處理原材料的方法。通過力學原理來分析和實現(xiàn)這些重要的特性,如那些靜態(tài)反應(yīng)的能量和摩擦力的最佳利用,像動力慣性、加速動力和能量;包括彈性材料的強度、應(yīng)力和剛度等材料的物理特性,以及流體潤滑和驅(qū)動器的流體力學。設(shè)計的過程是重復和合作的過程,無論是正式或非正式的進行,對設(shè)計者來說每個階段都很重要。?
最后,以圖樣為設(shè)計的標準,并建立將來的模型。如果它的測試是符合事先要求的,則再將對初步設(shè)計進行某些修改,使它能夠在制造成本上有所降低。產(chǎn)品的設(shè)計需要不斷探索和發(fā)展。許多方案必須被研究、試驗、完善,然后決定使用還是放棄。雖然每個工程學問題的內(nèi)容是獨特的,但是設(shè)計師可以按照類似的步驟來解決問題。?
產(chǎn)品的責任訴訟迫使設(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)未能預見和考慮材料的合理用途(如有可能,設(shè)計人員還應(yīng)進一步預測和考慮由于產(chǎn)品使用方法不當造成的后果。在近年來的許多產(chǎn)品責任訴訟案件中,由于錯誤地使用產(chǎn)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,尤其是當其性能數(shù)據(jù)長期不更新;(d)質(zhì)量控制方法不適當和未經(jīng)驗證;(e)由一些完全不稱職的人員選擇材料。?
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而存在的結(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)而指明方向。盡管采用最好的材料選擇方法也不能避免發(fā)生產(chǎn)品責任訴訟,設(shè)計人員和工業(yè)界按照適當?shù)某绦蜻M行材料選擇,可以大大減少訴訟的數(shù)量。?
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。?
在隨后生產(chǎn)和售后服務(wù)的幾年中,要接受新觀念的變化,或者由試驗和經(jīng)驗為基礎(chǔ),進一步分析并改進。??
一些設(shè)計規(guī)則?
在本節(jié)中,建議要運用創(chuàng)造性的態(tài)度來替代和改進。也許會創(chuàng)造出更實用、更經(jīng)濟、更耐用的產(chǎn)品。?
為了激發(fā)創(chuàng)造性思維,下列是設(shè)計和分析的建議規(guī)則。前六個規(guī)則對設(shè)計者來說特別適用。?
1.?要有創(chuàng)造性的利用所需要的物理性質(zhì)和控制過程。?
2.?認識負載產(chǎn)生的影響及其意義。?
3.?預測沒有想到的負載。
4.?創(chuàng)造出對載荷更為有利的條件。?
5.?提供良好的應(yīng)力分布和最小的剛度條件。?
6.?運用最簡單的方程來優(yōu)化體積和面積。?
7.?選擇組合材料。?
8.?仔細選擇所備的原料和不可缺少的組件。?
9.?調(diào)整有效的設(shè)計方案,以適應(yīng)生產(chǎn)過程和降低成本。?10.?規(guī)定好準確的位置條件為了使組件安裝時不干涉。?
機械設(shè)計包括一下內(nèi)容:?
1.?對設(shè)計過程、設(shè)計所需要公式以及安全系數(shù)進行介紹。?
2.?回顧材料特性、靜態(tài)和動態(tài)載荷分析,包括梁、振動和沖擊載荷。
3.?回顧應(yīng)力的基本規(guī)律和失效分析。?
4.?介紹靜態(tài)失效理論和靜態(tài)載荷下機械斷裂分析。?
5.?介紹疲勞失效理論并強調(diào)在壓力條件下接近高循環(huán)的疲勞設(shè)計,這通常用在旋轉(zhuǎn)機械的設(shè)計中。?
6.?深入探討機械磨損機理、表面接觸應(yīng)力和表面疲勞現(xiàn)象。?
7.?使用疲勞分析技術(shù)校核軸的設(shè)計。?
8.?討論潤滑油膜與滾動軸承的理論和應(yīng)用。?
9.?深入介紹直齒圓柱齒輪的動力學、設(shè)計和應(yīng)力分析,并簡單介紹斜齒輪、錐齒輪和渦輪有關(guān)方面的問題。?
10.?討論彈簧設(shè)計、螺桿等緊固件的設(shè)計,包括傳動螺桿和預緊固件。?
11.?介紹盤式和鼓式離合器以及制動器的設(shè)計和技術(shù)說明。??
機械設(shè)計?
一臺完整機器的設(shè)計是一個復雜的過程。機械設(shè)計是一項創(chuàng)造性的工作。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、工程材料、材料力學和機械制造工藝學等方面具有深厚的基礎(chǔ)知識。?
任何產(chǎn)品在設(shè)計時第一步就是選擇產(chǎn)品每個部分的構(gòu)成材料。許多的材料被今天的設(shè)計師所使用。對產(chǎn)品的功能,它的外觀、材料的成本、制造的成本作出必要的選擇是十分重要的。對材料的特性必須事先作出仔細的評估。?
仔細精確的計算是必要的,以確保設(shè)計的有效性。在任何失敗的情況下,最好知道在最初設(shè)計中有有缺陷的部件。計算(圖紙尺寸)檢查是非常重要的。一個小數(shù)點的位置放錯,就可以導致一個本可以完成的項目失敗。設(shè)計工作的各個方面都應(yīng)該檢查和復查。?
計算機是一種工具,它能夠幫助機械設(shè)計師減輕繁瑣的計算,并對現(xiàn)有數(shù)據(jù)提供進一步的分析?;酉到y(tǒng)基于計算機的能力,已經(jīng)使計算機輔助設(shè)計(CAD)和計算機輔助制造(CAM)成為了可能。心理學家經(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。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)計同管理人員進行交流和磋商,并得到批準。這一般是通過口頭討論,草圖和文字材料進行的。?
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,只有當它們被應(yīng)用在產(chǎn)品上才能產(chǎn)生效益。因而,應(yīng)該認識到在一個特定的產(chǎn)品進行設(shè)計之前,必須先確定人們是否需要這種產(chǎn)品。?
應(yīng)當把機械設(shè)計看成是機械設(shè)計人員運用創(chuàng)造性的才能進行產(chǎn)品設(shè)計、系統(tǒng)分析和制定產(chǎn)品的制造工藝學的一個良機。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)該認真精確的進行所有運算。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。?
一個好的設(shè)計人員應(yīng)該勇于提出新的想法,而且愿意承擔一定的風險,當新的方法不適用時,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)該不斷地探索改進現(xiàn)有的產(chǎn)品的方法,在此過程中應(yīng)該認真選擇原有的、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。?
新設(shè)計本身會有許多缺陷和未能預料的問題發(fā)生,只有當這些缺陷和問題被解決之后,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。