外文翻译--机构和机器原理.doc -- 5 元

英文原文MECHANISMSANDMACHINETHEORY1.IntroductiontoMechanismThefunctionofamechanismistotransmitortransformmotionfromonerigidbodytoanotheraspartoftheactionofamachine.Therearethreetypesofcommonmechanicaldevicesthatcanbeusedasbasicelementsofamechanism.1、Gearsystem,inwhichtoothedmembersincontacttransmitmotionbetweenrotatingshafts.2、Camsystem,whereauniformmotionofaninputmemberisconvertedintoanonuniformmotionoftheoutputmember.3、Planeandspatiallinkagesarealsousefulincreatingmechanicalmotionsforapointorrigidbody.Akinematicchainisasystemoflinks,thatis,rigidbodies,whichareeitherjointedtogetherorareincontactwithoneanotherinamannerthatpermitsthemtomoverelativetooneanother.Ifoneofthelinksisfixedandthemovementofanyotherlinktoanewpositionwillcauseeachoftheotherlinkstomovetodefinitepredictableposition,thesystemisaconstrainedkinematicchain.Ifoneofthelinksisheldfixedandthemovementofanyotherlinktoanewpositionwillnotcauseeachoftheotherlinkstomovetoadefinitepredictablepositionthenthesystemisanunconstrainedkinematicchain,Amechanismorlinkageisaconstrainedkinematicchain,andisamechanicaldevicethathasthepurposeoftransferringmotionand/orforcefromasourcetoanoutput.Alinkageconsistsoflinksorbars,generallyconsideredrigid,whichareconnectedbyjoints,suchaspinCorrevoluteorprismaticjoints,toformopenorclosedchainsorloops.Suchkinematicchains,withatleastonelinkfixed,becomemechanismsifatleasttwootherlinksremainmobility,orstructuresifnomobilityremains.Inotherwords,amechanismpermitsrelativemotionbetweenitsrigidlinksastructuredoesnot.Sincelinkagesmakesimplemechanismsandcanbedesignedtoperformcomplextasks,suchasnonlinearmotionandforcetransmissiontheywillreceivemuchattentioninmechanismstudy.Mechanismsareusedinagreatvarietyofmachinesanddevices.Thesimplestclosedlooplinkageisthefourbarlinkage,whichhasthreemovinglinksplusonefixedlinkandfourpinjoints.Thelinkthatisconnectedtothepowersourceorprimemoverandhasonemovingpivotandonegroundpivotiscalledtheinputlink.Theoutputlinkconnectsanothermovingpivottoanothergroundpivot.Thecouplerorfloatinglinkconnectedthetwomovingpivots,therebycouplingtheinputtotheoutputlink.Thefourbarlinkagehassomespecialconfigurationscreatedbymakingoneormorelinksinfiniteinlength.Theslidercrankorcrankandslidermechanismisafourbarchainwithasliderreplacinganinfinitelylongoutputlink.Theinternalcombustionengineisbuiltbasedonthismechanism.Otherformsoffourlinkmechanismsexistinwhichasliderisguidedonamovinglinkratherthanonafixedlink.Thesearecalledinversionsoftheslidercrank,producedwhenanotherlinkthecrank,coupler,orsliderisfixedlink.Althoughthefourbarlinkageandslidercrankmechanismareveryusefulandfoundinthousandsofapplications,wecanseethattheselinkageshavelimitedperformancelevel.Linkageswithmoremembersareoftenusedinmoredemandingcircumstances.Howeveritisoftendifficulttovisualizethemovementofamultilooplinkage,especiallywhenothercomponentsappearinthesamediagram.Thefirststepinthemotionanalysesofmorecomplicatedmechanismsistosketchtheequivalentkinematicorskeletondiagram.Theskeletondiagramservesapurposesimilartothatoftheelectricalschematicorcircuitdiagram.OrganizationmovementanalysissecondstepDrawsagraphicchart,ismustdeterminetheorganizationthenumberofdegreesoffreedom.Basedondegreeoffreedom,butItalyrefersneedscertainindependentinputsthemovementnumber,bydeterminedorganizationallcomponentsareoppositeinthegroundposition.Thepeoplehavethousandsofdifferenttypesconceivablythelinkmotiongear.YoumayimagineabagcontainingmassivelinkmotiongearthecomponentTwopolegroups,threepolegroups,fourpolegroupsandsoon,aswellascomponents,rotation,motion,camfollower,gear,toothchain,chainwheel,leatherbelt,beltpulleyandsoon.Spheremovement,screwviceaswellasthepermissionthreedimensionalrelativemotionotherconnectionsnotyetincludes,here,discussesinparallelplanesmerelyplanemotion.Moreoveryouconceivableputthesecomponentsvarioustypeslinkmotiongearpossibilitywhichformsinthesameplace.HowexistshelpsthepeopletocontrolformstheseorganizationstheruleInfact,themajorityorganizationdutyisrequestsasoleinputtotransmittoasoleoutput.Thereforethesingledegreeoffreedomorganizationusesmostonekindoforganizationtype.Forexample,namelymayseebytheintuitionFourpoleorganizationsareasingledegreeoffreedomlinkmotiongear.Thepicturemotiondiagramandthedeterminationorganizationdegreeoffreedomprocess,isthemovementanalysisandthesynthesisprocessfirststage.Inthemovementanalysis,addsonitscharacteristicaccordingtotheorganizationgeometryshapewhichpossiblyknewforexampleinputangle,speed,angleaccelerationandsoonstudiesthedeterminationconcreteorganization.Ontheotherhand,themovementsynthesisisdesignsanorganizationtocompletethedutyprocesswhichaninstituterequests.Inthis,choosestheneworganizationthetypeandthesizeisamovementsynthesispart.Conceivestherelativemotionability,canguessthereasonthatdesignsanorganizationthereasonandmakestheimprovementtoaconcretedesignabilityislikethisasuccessfulorganizationscientistssymbol.Althoughtheseabilitiescomefromthecongenitalcreativity,howevermoreisbecausehasgraspedthetechnologywhichenhancesfromthepractice.1.1Themovementanalysissimpleoneofmostusefulorganizationsisfourpoleorganizations.Inonfollowingelaborationmajorityofcontentcentralismdiscussionlinkmotiongear,butthisprocedureisalsosuitableforthemorecomplexlinkmotiongear.Wealreadyknewfourpoleorganizationshaveadegreeoffreedom.Aboutfourpoleorganizations,hastheusefulmorecontentswhichmustknowIndeedissomeThesepulltheXiaohusbandcriterionincludingthestandard,thetransformationconcept,theblindspotpositiondivergencepoint,branchoffice,transmissionangle,withtheirsmovementcharacteristic,includingposition,speedandacceleration.Fourpoleorganizationsmayhaveonekindofbeingcalledascrankrockerorganizationform,onekindofdoublerockingleverorganization,onekindofdoublecranktensionbardoestheorganization,whichoneformsendiniscalledastheorganization,isdecidedintwopolemovementscopeswhichfixedcomponentconnectswiththerack.Thecrankrockerorganizationinputcomponent,thecrankmayrevolvethrough360°andthecontinuousrotation,butoutputsthecomponenttomaketheundulationmerelyi.e.swingmember.Asanexceptionalcase,intheparallelfourpoleorganization,inputsthepolethelengthtobeequaltooutputsthepolethelength,thegobetweenlengthandthefixedlinkracklength,alsoisequal.Itsinputandtheoutputallmaymakethecompletealternationrotationortransformthebeingcalledasantiparallelquadrangleorganizationtheoverlappingstructure.ThestandardpullstheXiaohusbandcriteriontheoremtoindicatethat,Ifinfourpoleorganizations,betweentwopolescandowillfullyrelativelyrotatescontinuously,that,itslongestpolelengthissmallerthansumofwiththeshortestpolelengthorisequaltosumoftheothertwopolelength.ShouldpayattentionThesamefourpoleorganization,mayhavethedifferentform,whichpoleisthisdecidedinwasstipulatedi.e.makesfixedlinkastherack.Themovementtransformationprocessisinthefixedorganizationtransmissionchaindifferentmemberhasthedifferentorganizationrateprocess.Besideshasaboutthecomponentrotationscopeknowledge,butalsomusthavehowcausestheorganizationbeforethemanufactureonenergytherevolutionthegoodmeasure,thatwillbeveryuseful.HardenberghHartenbergspeaksofTherevolutionisterminology,itssignificancepassestooutputsthecomponentthemovementvalidity.Itmeanttherevolutionissteady,inwhichcaninoutputinthecomponenttohaveastrengthorthetorquebiggestforcecomponentiseffective.Notonlyalthoughthefinaloutputstrengthorthetorquearetheconnectingrodgeometricfigurefunctions,moreoveralsoisgenerallythepowerortheforceofinertiaresult,thatisfrequentlybigtolikestaticstrengthseveraltimes.Inordertoanalyzetheidlingorinordertoeasytoobtainhowcancauseanyorganizationtherevolutiontheindex,thetransmissionangleconceptisextremelyuseful.Inorganizationmovementperiod,thetransmissionanglevalueischanging.Thetransmissionangle0°mayoccurinthespecialposition.Willoutputthepolebutinthisspecialpositionthemovementwithnottoexertinputsonthepolethestrengthmanytohavenothingtodowithgreatly.Infact,asaresultofthemovementvicefrictioninfluence,thegeneralbasispracticalexperience,withthetransmissionangleplanningboardwhichisbiggerthantherating.Theweightlinkmotiongeartransmissionmovementabilitymatrixfoundationdefinitionalreadystudied.Adeterminingfactorvalueitincludesregardingsomeassignsorganizationgraph,positionoutputmovementvariabletoinputvariablederivativeisathislinkmotiongearinconcretepositionmobilitycriterion.Iftheorganizationhasadegreeoffreedome.g.fourpoleorganizations,thenstipulatedalocationparameter,iftheinputangle,completelydeterminedthisorganizationstopspositionneglectbranchofficespossibility.Wemaystudyoneaboutfourpoleorganizationcomponentabsoluteangularpositionanalysisexpression.Whenanalyzescertainpositionsandorcertaindifferentorganizationtime,thiswillbemustbemuchmoreusefulthanthegeometricfigureanalysisprogram,becausethisexpressionwillcausetheautomatedcomputationeasytoprogram.Therealizationorganizationspeedanalysisrelativevelocitylawisthespeedpolygonisoneofseveraleffectivemethods.Thisendgoesagainstthespottorepresentonthe