外文翻譯-機(jī)械設(shè)計(jì)及加工工藝

英文原文附錄MechanicalDesignandManufacturingProcessesMechanicaldesignistheapplicationofscienceand technologytodeviseneworimprovedproductsforthepurposeofsatisfyinghumanneeds.Itisavastfieldofengineeringtechnologywhichnotonlyconcernsitselfwiththeoriginalconceptionoftheproductintermsofitssize,shapeandconstructiondetails,butalsoconsidersthevariousfactorsinvolvedinthemanufacture,marketinganduseoftheproduct.Peoplewhoperformthevariousfunctionsofmechanicaldesignaretypicallycalleddesigners,ordesignengineers.Mechanicaldesignisbasicallyacreativeactivity.However,inadditiontobeinginnovative,adesignengineermustalsohaveasolidbackgroundintheareasofmechanicaldrawing,kinematics,dynamics,materialsandmanufacturingprocesses.engineering,strengthofmaterialsandmanufacturingprocesses.Asstatedpreviously,discoveriesandscientificbenefitpeople;onlyiftheyarethepurposeofmechanicaldesignistoAsstatedpreviously,discoveriesandscientificbenefitpeople;onlyiftheyareproduceaproductwhichwillserveaneedforman.Inventions,knowledgebythemselvesdonotnecessarilyincorporatedintoadesignedproductproduceaproductwhichwillwillabenefitbederived.Itshouldberecognized,therefore,thatahumanneedmustbeidentifiedbeforeaparticularproductisdesigned.Mechanicaldesignshouldbeconsideredtobeanopportunitytouseinnovativetalentstoenvisionadesignofaproduct,toanalyzethesystemandthenmakesoundjudgmentsonhowtheproductistobemanufactured.Itisimportanttounderstandthefundamentalsofengineeringratherthanmemorizemerefactsandequations.Therearenofactsorequationswhichalonecanbeusedtoprovideallthecorrectdecisionsrequiredtoproduceagooddesign.Ontheotherhand,anycalculationsmademustbedonewiththeutmostcareandprecision.Forexample,ifadecimalpointismisplaced,anotherwiseacceptable designmaynotfunction.Gooddesignsrequiretryingnewideasandbeingwillingtotakeacertainamountofrisk,knowingthatifthenewideadoesnotworktheexistingmethodcanbereinstated.Thusadesignermusthavepatience,sincethereisnoassuranceofsuccessforthetimeandeffortexpended.Creatingacompletelynewdesigngenerallyrequiresthatmanyoldandwell-establishedmethodsbethrustaside.Thisisnoteasysincemanypeopleclingtofamiliarideas,techniquesandattitudes.Adesignengineershouldconstantlysearchforwaystoimproveanexistingproductandmustdecidewhatold,provenconceptsshouldbeusedandwhatnew,untriedideasshould beincorporated.Newdesignsgenerallyhave"bugs"orunforeseenproblemswhichmustbeworkedoutbeforethesuperiorcharacteristicsofthenewdesignscanbeenjoyed.Thusthereisachanceforasuperiorproduct,butonlyathigherrisk.Itshouldbeemphasizedthat,ifadesigndoesnotwarrantradicalnewmethods,suchmethodsshouldnotbeappliedmerelyforthesakeofchange.Duringthebeginningstagesofdesign,creativityshouldbeallowedtoflourishwithoutagreatnumberofconstraints.Eventhoughmanyimpracticalideasmayarise,itisusuallyeasytoeliminatethemintheearlystagesofdesignbeforefirmdetailsarerequiredbymanufac- turing.Inthis way,innovativeideasarenotinhibited.Quiteoften,morethanonedesignisdeveloped,uptothepointwheretheycanbecomparedagainsteachother.Itisentirelypossiblethatthedesignwhichisultimatelyacceptedwilluseideasexistinginoneoftherejecteddesignsthatdidnotshowasmuchoverallpromise.Psychologistsfrequently talkabouttryingtofitpeopletothemachinestheyoperate.Itisessentiallytheresponsibility ofthedesignengineertostrivetofitmachinestopeople.Thisisnotaneasytask,sincethereisreallynoaveragepersonforwhichcertainoperatingdimensionsandproceduresareoptimum.Anotherimportantpointwhichshouldberecognizedisthatadesignengineermustbeabletocommunicateideastootherpeopleiftheyaretobeincorporated.Communicatingthedesigntoothersisthefinal,vitalstepinthedesignprocess.Undoubtedlymanygreatdesigns,inventions,andcreativeworkshavebeenlosttomankind

simplybecausetheoriginatorswereunableorunwillingtoexplaintheiraccomplishmentstoothers.Presentationisasellingjob.Theengineer,whenpresentinganewsolutiontoadministrative,management,orsupervisorypersons,isattemptingtosellortoprovetothemthatthissolutionisabetterone.Unlessthiscanbedonesuccessfully,thetimeandeffortspentonobtainingthesolutionhavebeenlargelywasted.Basically,thereareonlythreemeansofcommunicationavailabletous.Thesearethewritten,theoral,andthegraphicalforms.Thereforethesuccessfulengineerwillbetechnically competentandversatile inallthreeformsofcommunication.Atechnicallycompetentpersonwholacksabilityinanyoneoftheseformsisseverelyhandicapped.Ifabilityinallthreeformsislacking,noonewilleverknowhowcompetentthatpersonThecompetentofnotsucceedingshouldbeexpectedengineershouldnotinapresentation.becausefailureoris!beafraidInfact,criticismofthepossibilityoccasionalfailureseemstoaccompanyeveryreallycreativeidea.Thereisagreatdealtobelearnedfromafailure,andriskdefeat.decidingnoteffectively,severelyhandicapped.Ifabilityinallthreeformsislacking,noonewilleverknowhowcompetentthatpersonThecompetentofnotsucceedingshouldbeexpectedengineershouldnotinapresentation.becausefailureoris!beafraidInfact,criticismofthepossibilityoccasionalfailureseemstoaccompanyeveryreallycreativeidea.Thereisagreatdealtobelearnedfromafailure,andriskdefeat.decidingnoteffectively,thegreatestgainsareobtainedbythosewillingtoInthefinalanalysis,therealfailurewouldlieintomakethepresentationatall.thefollowingquestionsmustbeanswered:TocommunicateDoesthedesignreallyserveahumanneed?Willitbecompetitivewithexistingproductsofrivalcompanies?Isiteconomical toproduce?Canitbereadilymaintained?Willitsellandmakeaprofit?Onlytimewillprovidethetrueanswerstotheprecedingquestions,buttheproductshouldbedesigned,manufacturedandmarketedonlywithinitialaffirmativeanswers.Thedesignengineeralsomustcommunicatethefinalizeddesigntomanufacturingthroughtheuseofdetailandassemblydrawings.Quiteoften,aproblemwilloccurduringthemanufacturingcycle[3].Itmaybethatachangeisrequiredinthedimensioningortolerancingofapartsothatitcanbemorereadilyproduced.Thisfailsinthecategoryofengineeringchangeswhichmustbeapprovedbythedesignengineersothattheproductfunctionwillnotbeadverselyaffected.Inothercases,adeficiencyinthedesignmayappearduringassemblyortestingjustpriortoshipping.Theserealitiessimplybearoutthefactthatdesignisalivingprocess.Thereisalwaysabetterwaytodoitandthedesignershouldconstantlystrivetowardsfindingthatbetterway.Designingstartswithaneed,realorimagined.Existingapparatusmayneedimprovementsindurability,efficiently,weight,speed,orcost.Newapparatusmaybeneededtoperformafunctionpreviouslydonebymen,suchascomputation,assembly,orservicing.Withtheobjectivewhollyorpartlydefined,thenextstepindesignistheconceptionofmechanismsandtheirarrangementsthatwillperformtheneededfunctions.Forthis,freehandsketchingisofgreatvalue,notonlyasarecordofone'sthoughtsandasanaidindiscussionwithothers,butparticularlyforcommunicationwithone'sownmind,asastimulantforcreativeideas.Whenthegeneralshapeandafewdimensionsoftheseveralcomponentsbecomeapparent,analysiscanbegininearnest.Theanalysiswillhaveasitsobjective satisfactory orsuperiorperformance,plussafetyanddurability withminimumweight,andacompetitiveeast.Optimumproportionsanddimensionswillbesoughtforeachcriticallyloadedsection,togetherwithabalancebetweenthestrengthoftheseveralcomponents.Materialsandtheirtreatmentwillbechosen.Theseimportantobjectivescanbeattainedonlybyanalysisbasedupontheprinciplesofmechanics,suchasthoseofstaticsforreactionforcesandfortheoptimumutilization offriction; ofdynamicsforinertia,acceleration,andenergy;ofelasticity andstrengthofmaterialsforstressanddeflection;andoffluidmechanicsforlubricationandhydrodynamicdrives.Finally,adesignbaseduponfunctionandreliabilitywillbecompleted,andaprototypemaybebuilt.Ifitstestsaresatisfactory,andifthedeviceistobeproducedinquantity,the

initialdesignwillundergocertainmodificationsthatenableittobemanufacturedinquantityatalowercost.Duringsubsequentyearsofmanufactureandservice,thedesignislikelytoundergochangesasnewideasareconceivedorasfurtheranalysisbasedupontestsandexperienceindicatealterations.Salesappeal,customersatisfaction,andmanufacturecostareallrelatedtodesign,andabilityindesignisintimatelyinvolvedinthesuccessofanengineeringventure.Tostimulatecreativethought,thefollowingrulesaresuggestedforthedesigner.Applyingenuitytoutilizedesiredphysicalpropertiesandtocontrolundesiredones.Theperformancerequirementsofamachinearemetbyutilizinglawsofnatureorpropertiesofmatter(e.g., flexibility,strength,gravity,inertia,buoyancy,centrifugalfor,principlesoftheleverandinclinedplane, friction, viscosity,fluidpressure,andthermalexpansion),alsothemanyelectrical,optical,thermal,andchemicalphenomena.However,whatmaybeusefulinoneapplicationmaybedetrimentalinthenext.Flexibilityisdesiredinvalvespringsbutnotinthevalvecamshaft;frictionisdesiredattheclutchfacebutnotintheclutchbearing.Ingenuityindesignshouldbeappliedtoutilizeandcontrolthephysicalpropertiesthataredesiredandtominimizethosethatarenotdesired.andstiffnesswithtofluctuatingstress,concentration,Provideforfavorablestressdistributeminimumweight.Oncomponentssubjectedparticularattentionisgiventoareductioninstressandtoanincreaseofstrengthatfillets,threads,holes,andfits.andstiffnesswithtofluctuatingstress,concentration,Stressreductionaremadebymodificationinshape,andstrengtheningStressreductionaremadebymaybedonebyprestressingtreatmentssuchassurfacerollingandshallowhardening.Hollowshaftsandtubing,andboxsectionsgiveafavorablestressdistribution, togetherwithstiffness andminimumweight.Sufficientstiffness tomaintainalignmentanduniformpressurebetweencontactingsurfacesshouldbeprovidedforcrank,cam,andgearshafts,andforenclosuresandframescontainingbearingsupports.The stiffnessofshaftsandother componentsmust

besuitabletoavoidresonantvibrations.Use&zsicequationstocalculateandoptimizedimensions.Thefundamentalequationsofmechanicsandtheothersciencesaretheacceptedbasesforcalculations.Theyaresometimesrearrangedinspecialformstofacilitatethedeterminationoroptimizationofdimensions,suchasthebeamandsurfacestressequationsfordetermininggear-toothsize.Factorsmaybeaddedtoafundamentalequationforconditionsnotanalyticallydeterminable,e.g.,onthinsteeltubes,anallowanceforcorrosionaddedtothethicknessbasedonpressure.Whenitisnecessarytoapplyafundamentalequationtoshapes, materials,orconditionswhichonlyapproximatetheassumptionsforitsderivation,itisdoneinamannerwhichgivesresults"onthesafeside".Insituationswheredataareincomplete, equationsofthesciencesmaybeusedasproportioningguidestoextendasatisfactorydesigntonewcapacities.Choosematerialsforacombinationofproperties.Materialsshouldbechosenforacombinationofpertinentproperties,notonlyforstrengths,hardness,andweight,butsometimesforresistance toimpact,corrosion,andloworhightemperatures.Costandfabricationproperties arefactors,sensitivity tovariationproperties arefactors,sensitivity tovariationcoating.4.Selectcarefully4.Selectcarefullybyadesignerpreviouslydevelopedcomponentsisfrequentlyselectedandhiscompanyfromthestocksofpartsmanufacturers,ifthecomponentmeettheperformanceandreliabilityrequirementsandisadaptablewithoutadditionaldevelopmentcoststotheparticularmachinebeingdesigned.However,itsselectionshouldbecarefullymadewi'thafullknowledgeofitspropcrties,sincethereputationandliabilityofthecompanysufferifthereisafailureinanyoneofthemachine'sparts.Inothereasesthestrength,reliability,andcostrequirementsarebettermetifthedesignerofthemachinealsodesignsthecomponent,withtheparticularadvantageofcompactnessifitisdesignsintegralwithothercomponents,e.g.,gearstobeforgedinclustersorintegralwithashaft.byadesigner6.Provideforaccuratelocationandnoninterferenceofpartsinassembly.Agooddesignprovidesforthecorrectlocatingofpartsandforeasyassemblyandrepair.Shouldersandpilotsurfacesgiveaccuratelocationwithoutmeasurementduringassembly.Shapescanbedesignedsothatpartscannotbe assembledbackwardsorinthewrongplace.Interferences,asbetweenscrewsintappedholes,andbetweenlinkagesmustheforeseenandpretended.Inaccuratealignmentandpositioningbetweensuchassembliesmustbeavoided,orprovisionmustbemadetominimizeanyresultingdetrimentaldisplacementsandstresses.Thehumanracehasdistinguisheditselffromallotherformsoflifebyusingtoolsandintelligencetocreateitemsthatservetomakelifeeasierandmoreenjoyable.Throughthecenturies,boththetoolsandtheenergysourcestopowerthesetoolshaveevolvedtomeettheincreasingsophisticationandcomplexityofmankind'sideas.Intheirearliestforms,toolsprimarilyconsistedofstoneinstruments.Consideringtilerelativesimplicityoftheitemsbeingmadeandthematerialsbeingshaped,stonewasadequate.Whenirontoolswereinvented,durablemetalsandmoresophisticatedarticlescouldbeproduced.Thetwentiethcenturyhasseenthecreationofproductsmadefromthemostdurableand,consequently,themostunmachinablematerialsinhistory.Inanefforttomeetthemanufacturingchallengescreatedbythesematerials,toolshavenowevolvedtoincludematerialssuchasalloysteel,carbide,diamond,andceramics.Asimilarevolutionhastakenplacewiththemethodsusedtopowerourtools.Initially,toolswerepoweredbymuscles;eitherhumanoranimal.Howeverasthepowersofwater,wind,steam,andelectricitywereharnessed,mankindwasabletofurtherextendedmanufacturingcapabilitieswithnewmachines,greateraccuracy,andfastermachiningrates.Everytimenewtools,toolmaterials,andpowersourcesareutilized,theefficiencyandcapabilitiesofmanufacturersaregreatlyenhanced.Howeverasoldproblemsaresolved,newproblems

andchallengesarisesothatthemanufacturersoftodayarefacedwithtoughquestionssuchasthe following:Howdoyoudrilla2mmdiameterhole670mmdeepwithoutexperiencingtaperorrunout?Isthereawaytoefficientlydeburrpassagewaysinsidecomplexcastingsandguarantee100%thatnoburrsweremissed?Isthereaweldingprocessthatcaneliminatethethermaldamagenowoccurringtomyproduct?Sincethe1940s,arevolutioninmanufacturinghasbeentakingplacethatonceagainallowsmanufacturerstomeetthedemandsimposedbyincreasinglysophisticateddesignsanddurable,butinmanycasesnearlyunmachinable,materials.Thismanufacturingrevolutionisnow,asithasbeeninthepast,centeredontheuseofnewtoolsandnewformsofenergy.Theresulthasbeentheintroductionofnewmanufacturingprocessesusedformaterialremoval,forming,andjoining,knowntodayasnontraditionalmanufacturingprocesses.Theconventionalmanufacturingprocessesinusetodayformaterialremovalprimarilyrelyonelectricmotorsandhardtoolmaterialstoperformtaskssuchassawing,drilling,anbroaching.ConventionalformingoperationsareperformedwiththeenergyfromLikewise,materialjoiningelectricmotors,hydraulics,andgravity.Likewise,materialjoiningisconventionallyaccomplishedwiththermalenergysourcessuchasisconventionallyaccomplishedwiththermalenergysourcessuchasburninggasesandelectricarcs.manufacturingprocessesharnessIncontrast,nontraditionalenergysourcesconsideredunconventionalbyyesterday'sstandards.Materialremovalcannowbeaccomplishedwithelectrochemicalreactions,high-temperatureplasmas,andhigh-velocityjetsofliquidsandabrasives.Materialsthatinthepasthavebeenextremelymanufacturingprocessesharnessdifficulttoform,arenowformedwithmagneticfields,explosives,andtheshockwavesfrompowerfulelectricsparks.Material-joiningcapabilitieshavebeenexpandedwiththeuseofhigh-frequencysoundwavesandbeamsofformedwithmagneticfields,explosives,andtheshockwavesfrompowerfulelectricsparks.Material-joiningcapabilitieshavebeenexpandedwiththeuseofhigh-frequencysoundwavesandbeamsofelectrons.Inthepast50years,over20Inthepast50years,over20differentnontraditionalmanufacturingprocesseshavebeeninventedandsuccessfullymanufacturingimplementedintoproduction.Thereasontherearesuchalargenumberofnontraditionalprocessesisthesamereasontherearesuchalargenumberofconventionalprocesses;eachprocesshasitsowncharacteristicattributesandlimitations,hencenooneprocessisbestforallmanufacturingsituations.Forexample,nontraditionalprocessaresometimesappliedtoincreaseproductivityeitherbyreducingthenumberofoverallmanufacturingoperationsrequiredtoproduceaproductorbyperformingoperationsfasterthanthepreviouslyusedmethod.Inothercases,nontraditionalprocessesareusedtoreducetheInothercases,nontraditionalprocessesareusedtoreducethenumberofrejectsexperiencedbytheoldmanufacturingmethodbynumberofrejectsexperiencedbytheoldmanufacturingmethodbynontraditionalincreasingrepeatability,reducingin-processbreakageoffragileworkpieces,orbyminimizingdetrimentaleffectsonworkpieceproperties.nontraditionalBecauseoftheaforementionedattributes,manufacturingprocesseshaveexperiencedsteadygrowthsincetheirmanufacturingprocesseshaveexperiencedsteadygrowthsincetheirintroduction.Anincreasinggrowthratefortheseprocessesinthefutureisassuredforthefollowingreasons:1.Currently,nontraditionalintroduction.Anincreasinggrowthratefortheseprocessesinthefutureisassuredforthefollowingreasons:1.Currently,nontraditionalprocessespossessvirtuallyunlimitedcapabilitieswhencomparedwithconventionalprocesses,exceptforvolumetricmaterialremovalrates.Greatadvanceshaveunlimitedcapabilitieswhencomparedwithconventionalprocesses,exceptforvolumetricmaterialremovalrates.Greatadvanceshavebeenmadeinthepastfewyearsinincreasingtheremovalratesofbeenmadeinthepastfewyearsinincreasingtheremovalratesofsomeoftheseprocesses,andthereisnoreasontobelievethatthistrendwillnotcontinueintothefuture.2.Approximatelyonehalfofthenontraditionalmanufacturingprocessesareavailablewithcomputercontroloftheprocessparameters.Theuseofcomputerslendssimplicitytoprocessesthatpeoplemaybeunfamiliarwith,andtherebyacceleratesacceptance.Additionally,computercontrolassuresreliabilityandrepeatability[s],whichalsoacceleratesacceptanceandpeoplemaybeunfamiliarwith,andtherebyacceleratesacceptance.Additionally,computercontrolassuresreliabilityandrepeatability[s],whichalsoacceleratesacceptanceandimplementation.1.Mostnontraditionalprocessesarecapableofbeing1.Mostnontraditionalprocessesarecapableofbeingadaptively-controlledthroughtheuseofvisionsystems,lasergages,andotherin-processinspectiontechniques.If,forexample,theinprocessinspectionsystemdeterminesthatthesizeofholesbeingproducedinaproductarebecomingsmaller,thesizecanbemodifiedwithoutchanginghardtools,suchasdrills.4.Theimplementationofnontraditionalmanufacturingprocesseswillcontinustoincreaseasmanufacturingengineers,productdesigners,andmetallurgicalengineersbecomeincreasinglyawareoftheuniquecapabiltiesandbenefitsthat nontraditionalmanufacturingprocessesprovide.譯文機(jī)械設(shè)計(jì)及加工工藝機(jī)械設(shè)計(jì)是一門通過設(shè)計(jì)新產(chǎn)品或者改進(jìn)老產(chǎn)品，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。進(jìn)行各種機(jī)械設(shè)計(jì)工作的人員通常被稱為設(shè)計(jì)人員或者設(shè)計(jì)工程師。機(jī)械設(shè)計(jì)是一項(xiàng)創(chuàng)造性的工作。設(shè)計(jì)工程師不僅在工作上要有創(chuàng)新性，還必須在機(jī)械制圖、運(yùn)動學(xué)、動力學(xué)、工程材料、材料力學(xué)和機(jī)械制造工藝等方面具有深厚的基礎(chǔ)知識。如前面所述，機(jī)械設(shè)計(jì)的目的是生產(chǎn)滿足人類需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科學(xué)知識本身并不一定能給人類帶來益處，只有當(dāng)它們被用在產(chǎn)品上才能產(chǎn)生效益。因而，應(yīng)該認(rèn)識到在一個特定產(chǎn)品進(jìn)行設(shè)計(jì)之前，必須先確定人們是否需要這種產(chǎn)品。TOC\o"1-5"\h\z應(yīng)當(dāng)把機(jī)械設(shè)計(jì)看成設(shè)計(jì)人員運(yùn)用創(chuàng)造性的才能進(jìn)行產(chǎn)品設(shè)計(jì)、系統(tǒng)分析和制訂產(chǎn)品的制造工藝的一個良機(jī)。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(jì)中做出所需的全 部決定的。另一方面，應(yīng)該認(rèn)真精確地進(jìn)行所有運(yùn)算。例如，即使將一個小數(shù) 點(diǎn)的位置放錯，也會使正確的設(shè)計(jì)變成錯誤的。一個好的設(shè)計(jì)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(xiǎn)；當(dāng)新的方法不適用時，就恢復(fù)采用原來的方法。因此，設(shè)計(jì)人員必須要有耐心 ，因?yàn)樗ㄙM(fèi)的時間和努力并不能保證帶來成功。一個全新的設(shè)計(jì)，要求摒棄 許多陳舊的，為人們所熟知的方法。由于許多人易于墨守成規(guī)，這樣做并不是 一件容易的事情。一位設(shè)計(jì)工程師應(yīng)該不斷地探索改進(jìn)現(xiàn)有產(chǎn)品的辦法，在此 過程中應(yīng)該認(rèn)真選擇原有的、經(jīng)過驗(yàn)證的設(shè)計(jì)原理，將其與未經(jīng)過驗(yàn)證的新觀 念結(jié)合起來。新設(shè)計(jì)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(xiǎn)。應(yīng)該強(qiáng)調(diào)的是，如果設(shè)計(jì)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辦法。在設(shè)計(jì)的初始階段，應(yīng)該允許設(shè)計(jì)人員充分發(fā)揮創(chuàng)造性，不受各種約束。即使產(chǎn)生了許多不切合實(shí)際的想法，也會在設(shè)計(jì)的早期，即繪制生產(chǎn)圖紙之前被改正。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(jì)方案， 然后加以比較。很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。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(jī)器。設(shè)計(jì)人員的基本職責(zé)是努力使機(jī)器來適應(yīng)人們。這并不是一項(xiàng)容易的工作，因?yàn)閷?shí)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。另一個應(yīng)該被認(rèn)識到的重要問題是，設(shè)計(jì)工程師必須能夠同其他有關(guān)人員進(jìn)行交流和溝通。與其他人就設(shè)計(jì)方案進(jìn)行交流和溝通是設(shè)計(jì)過程的最后和 關(guān)鍵階段。毫無疑問，有許多偉大的設(shè)計(jì)、發(fā)明或創(chuàng)造之所以沒有為人類所利 用,就是因?yàn)閯?chuàng)造者不善于或者不愿意向其他人介紹自己的成果。提出方案是一 種說服別人的工作。當(dāng)一個工程師向經(jīng)營、管理部門或者其主管人員提出自己 的新方案時，就是希望向他們說明或者證明自己的方案是比較好的。只有成功 地完成這項(xiàng)工作，為得出這個方案所花費(fèi)的大量時間和精力才不會被浪費(fèi)掉。人們基本上只有三種表達(dá)自己思想的方式，即文字材料、口頭表述和繪圖。因此，一個優(yōu)秀的工程師除了掌握技術(shù)之外，還應(yīng)該精通這三種表達(dá)方式。 如果一個技術(shù)能力很強(qiáng)的人在上述三種表達(dá)方式中的某一種的能力較差，他就 會遇到很大的困難。如果上述三種能力都較差，那將永遠(yuǎn)沒有人知道他是一個多么能干的人!一個有能力的工程師不應(yīng)該害怕在提出自己的方案時遭到失敗的可能性。事實(shí)上，偶然的失敗肯定會發(fā)生的，因?yàn)槊總€真正有創(chuàng)造性的設(shè)想似乎總是有失敗或批評伴隨著它。從一次失敗中可以學(xué)到很多東西，只有不怕遭受失敗的人們才能取得最大的收獲?？傊?，決定不把方案提交出來，才是真正的失敗。為了進(jìn)行有效的交流，需要解決下列問題：所要設(shè)計(jì)的這個產(chǎn)品是否真正為人們所需要?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?生產(chǎn)這種產(chǎn)品是否經(jīng)濟(jì)?產(chǎn)品的維修是否方便?產(chǎn)品有無銷路?是否可以盈利?只有時間才能對上述問題給出正確的答案。但是，產(chǎn)品的設(shè)計(jì)、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(jì)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(jì)方案進(jìn)行溝通。通常，在制造過程中會出現(xiàn)某個問題?？赡芤髮δ硞€零件尺寸或公差做一些更改，使零件的生產(chǎn)變得容易。但是，工程上的更改必須經(jīng)過設(shè)計(jì)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(yùn)前的試驗(yàn)中才發(fā)現(xiàn)設(shè)計(jì)中的某種缺陷。這些事例恰好說明了設(shè)計(jì)是一個動態(tài)過程?？偸谴嬖谥玫姆椒▉硗瓿稍O(shè)計(jì)工作，設(shè)計(jì)人員應(yīng)該不斷努力，尋找這些更好的方法。設(shè)計(jì)是從實(shí)際或者假想的需要開始的。對于現(xiàn)有的設(shè)備可能需要在耐用性、效率、重量、速度或成本等方面做進(jìn)一些改進(jìn)工作；也可能需要新的設(shè)備完成以前由人來做的工作，例如計(jì)算或者裝配。當(dāng)目標(biāo)完全或部分被確定以后，下一個設(shè)計(jì)步驟是對能夠完成所需要功能的機(jī)構(gòu)及其布局進(jìn)行總體設(shè)計(jì)。對于此項(xiàng)工作，徒手畫的草圖是很有價(jià)值的，它不僅可以記錄下我們的想法，而且還有助于與別人進(jìn)行討論，特別是和自己的大腦進(jìn)行交流，從而促進(jìn)創(chuàng)新想法的產(chǎn)生。當(dāng)一些零件的大致形狀和幾個尺寸被確定后，就可以開始認(rèn)真的分析工作。分析工作的目的是要在重量最輕、成本最低的情況下，獲得令人滿意，即優(yōu)良的工作性能，并且還要安全耐用。對于每個關(guān)鍵承載截面，應(yīng)該尋求最佳的比例和尺寸，同時要對這幾個零件的受力進(jìn)行平衡。要對材料和處理方式進(jìn)行選擇。只有根據(jù)力學(xué)原理進(jìn)行分析才能達(dá)到這些重要目的。這些分析包括根據(jù)靜力學(xué)原理分析反作用力和充分利用摩擦力，根據(jù)動力學(xué)原理分析慣性、加速度和能量；根據(jù)彈性力學(xué)和材料力學(xué)分析應(yīng)力和變形；根據(jù)流體力學(xué)來分析潤滑和流體傳動。最后，完成基于功能要求和可靠性所進(jìn)行的設(shè)計(jì)，且要制作一臺樣機(jī)。如果試驗(yàn)結(jié)果令人滿意，而且該裝置將要進(jìn)行批量生產(chǎn)，就應(yīng)該對最初提出的設(shè)計(jì)方案做一些修改，使其能以較低的成本進(jìn)行批量生產(chǎn)。在以后的制造和使用期內(nèi)，如果產(chǎn)生了新的想法或者根據(jù)試驗(yàn)和經(jīng)驗(yàn)所做的進(jìn)一步分析結(jié)果表明，可以有更好的替代方案，則很可能對原設(shè)計(jì)方案進(jìn)行修改。銷售吸引力、客戶的滿意程度和制造成本均與設(shè)計(jì)有關(guān)，而設(shè)計(jì)能力則與工程創(chuàng)新的實(shí)現(xiàn)是密切相關(guān)的。為激發(fā)創(chuàng)造性思維，建議設(shè)計(jì)人員遵循下列準(zhǔn)則。1.創(chuàng)造性地利用所需要的物理性能和控制不需要的物理性能?？梢岳米匀环▌t或物質(zhì)的性能（例如柔性，強(qiáng)度，重力，慣性，浮力，離心力；杠桿原理和斜面原理，摩擦，粘性，流體壓力和熱膨脹）和許多電學(xué)，光學(xué)和化學(xué)現(xiàn)象來滿足一臺機(jī)器的設(shè)計(jì)要求。一種性能在某種場合下可能是有用的，而在另外 一TOC\o"1-5"\h\z種場合下則可能是有害的。閥門的彈簧應(yīng)該有柔性，而閥門的凸輪軸就不需 要柔性。離合器結(jié)合面上需要有摩擦，而離合器軸承卻不需要摩擦。設(shè)計(jì)時， 需要創(chuàng)造性地利用和控制所要的物理性能，將不需要的物理性能減至最小。2．在重量最輕的情況下，提供合理的應(yīng)力分布和剛度。對于承受交變應(yīng)力的零件，應(yīng)該特別注意減輕應(yīng)力集中和提高圓角，螺紋和配合處的強(qiáng)度。改 變零件的形狀，可以降低它所承受的應(yīng)力，對零件施加預(yù)應(yīng)力，如表面滾壓和 淺表面硬化，均可使其得到強(qiáng)化?？招妮S和空心管道，箱形截面能獲得有利的 應(yīng)力分布，同時具有強(qiáng)度高而重量最輕的特點(diǎn)。曲軸，凸輪軸以及含有軸承支 座的外殼和構(gòu)架都應(yīng)有足夠的剛度以保證直線對中精度和接觸表面之間的壓力 均勻分布。軸和其他零件須有適當(dāng)?shù)膭偠?，避?/p>