外文翻译-机构和机器原理.doc

毕业设计中英文翻译学生姓名：学号：学院：专业：指导教师：200X年X月XXXXXXXXX机械工程与自动化学院机械设计制造及其自动化XXX名字，三号楷体外文资料MECHANISMSANDMACHINETHEORY1.IntroductiontoMechanism：Thefunctionofamechanismistotransmitortransformmotionfromonerigidbodytoanotheraspartoftheactionofamachine.Therearethreetypesofcommonmechanicaldevicesthatcanbeusedasbasicelementsofamechanism.1、Gearsystem,inwhichtoothedmembersincontacttransmitmotionbetweenrotatingshafts.2、Camsystem,whereauniformmotionofaninputmemberisconvertedintoanonuniformmotionoftheoutputmember.3、Planeandspatiallinkagesarealsousefulincreatingmechanicalmotionsforapointorrigidbody.Akinematicchainisasystemoflinks,thatis,rigidbodies,whichareeitherjointedtogetherorareincontactwithoneanotherinamannerthatpermitsthemtomoverelativetooneanother.Ifoneofthelinksisfixedandthemovementofanyotherlinktoanewpositionwillcauseeachoftheotherlinkstomovetodefinitepredictableposition,thesystemisaconstrainedkinematicchain.Ifoneofthelinksisheldfixedandthemovementofanyotherlinktoanewpositionwillnotcauseeachoftheotherlinkstomovetoadefinitepredictablepositionthenthesystemisanunconstrainedkinematicchain,Amechanismorlinkageisaconstrainedkinematicchain,andisamechanicaldevicethathasthepurposeoftransferringmotionand/orforcefromasourcetoanoutput.Alinkageconsistsoflinks(orbars),generallyconsideredrigid,whichareconnectedbyjoints,suchaspinCorrevolute)orprismaticjoints,toformopenorclosedchains(orloops).Suchkinematicchains,withatleastonelinkfixed,becomemechanismsifatleasttwootherlinksremainmobility,orstructuresifnomobilityremains.Inotherwords,amechanismpermitsrelativemotionbetweenitsrigidlinks；astructuredoesnot.Sincelinkagesmakesimplemechanismsandcanbedesignedtoperformcomplextasks,suchasnonlinearmotionandforcetransmissiontheywillreceivemuchattentioninmechanismstudy.Mechanismsareusedinagreatvarietyofmachinesanddevices.Thesimplestclosed-looplinkageisthefour-barlinkage,whichhasthreemovinglinks(plusonefixedlink)andfourpinjoints.Thelinkthatisconnectedtothepowersourceorprimemoverandhasonemovingpivotandonegroundpivotiscalledtheinputlink.Theoutputlinkconnectsanothermovingpivottoanothergroundpivot.Thecouplerorfloatinglinkconnectedthetwomovingpivots,therebycouplingtheinputtotheoutputlink.Thefour-barlinkagehassomespecialconfigurationscreatedbymakingoneormorelinksinfiniteinlength.Theslider-crank(orcrankandslider)mechanismisafour-barchainwithasliderreplacinganinfinitelylongoutputlink.Theinternalcombustionengineisbuiltbasedonthismechanism.Otherformsoffour-linkmechanismsexistinwhichasliderisguidedonamovinglinkratherthanonafixedlink.Thesearecalledinversionsoftheslider-crank,producedwhenanotherlink(thecrank,coupler,orslider)isfixedlink.Althoughthefour-barlinkageandslider-crankmechanismareveryusefulandfoundinthousandsofapplications,wecanseethattheselinkageshavelimitedperformancelevel.Linkageswithmoremembersareoftenusedinmoredemandingcircumstances.Howeveritisoftendifficulttovisualizethemovementofamultilooplinkage,especiallywhenothercomponentsappearinthesamediagram.Thefirststepinthemotionanalysesofmorecomplicatedmechanismsistosketchtheequivalentkinematicorskeletondiagram.Theskeletondiagramservesapurposesimilartothatoftheelectricalschematicorcircuitdiagram.Organizationmovementanalysissecondstep:Drawsagraphicchart,ismustdeterminetheorganizationthenumberofdegreesoffreedom.Basedondegreeoffreedom,butItalyrefersneedscertainindependentinputsthemovementnumber,bydeterminedorganizationallcomponentsareoppositeinthegroundposition.Thepeoplehavethousandsofdifferenttypesconceivablythelinkmotiongear.Youmayimagineabagcontainingmassivelinkmotiongearthecomponent:Twopolegroups,threepolegroups,fourpolegroupsandsoon,aswellascomponents,rotation,motion,camfollower,gear,toothchain,chainwheel,leatherbelt,beltpulleyandsoon.(Spheremovement,screwvice-aswellasthepermissionthreedimensionalrelativemotionotherconnectionsnotyetincludes,here,discussesinparallelplanesmerelyplanemotion).Moreoveryouconceivableputthesecomponentsvarioustypeslinkmotiongearpossibilitywhichformsinthesameplace.Howexistshelpsthepeopletocontrolformstheseorganizationstherule?Infact,themajorityorganizationdutyisrequestsasoleinputtotransmittoasoleoutput.Thereforethesingledegreeoffreedomorganizationusesmostonekindoforganizationtype.Forexample,namelymayseebytheintuition:Fourpoleorganizationsareasingledegreeoffreedomlinkmotiongear.Thepicturemotiondiagramandthedeterminationorganizationdegreeoffreedomprocess,isthemovementanalysisandthesynthesisprocessfirststage.Inthemovementanalysis,addsonitscharacteristicaccordingtotheorganizationgeometryshapewhichpossiblyknew(forexampleinputangle,speed,angleaccelerationandsoon)studiesthedeterminationconcreteorganization.Ontheotherhand,themovementsynthesisisdesignsanorganizationtocompletethedutyprocesswhichaninstituterequests.Inthis,choosestheneworganizationthetypeandthesizeisamovementsynthesispart.Conceivestherelativemotionability,canguessthereasonthatdesignsanorganizationthereasonandmakestheimprovementtoaconcretedesignabilityis