外文翻译--认识曲柄摇臂机构设计的最优传动方法.doc
文献翻译英文原文:NOVELMETHODOFREALIZINGTHEOPTIMALTRANSMISSIONOFTHECRANK-AND-ROCKERMECHANISMDESIGNAbstract:Anovelmethodofrealizingtheoptimaltransmissionofthecrank-and-rockermechanismispresented.Theoptimalcombinationdesignismadebyfindingtherelatedoptimaltransmissionparameters.Thediagramoftheoptimaltransmissionisdrawn.Inthediagram,therelationamongminimumtransmissionangle,thecoefficientoftravelspeedvariation,theoscillatingangleoftherockerandthelengthofthebarsisshown,concisely,convenientlyanddirectly.Themethodpossessesthemaincharacteristic.Thatitistoachievetheoptimaltransmissionparametersunderthetransmissionanglebydirectlychoosinginthediagram,accordingtothegivenrequirements.Thecharacteristicsofthemechanicaltransmissioncanbeimprovedtogaintheoptimaltransmissioneffectbythemethod.Especially,themethodissimpleandconvenientinpracticaluse.Keywords:Crank-and-rockermechanism,Optimaltransmissionangle,CoefficientoftravelspeedvariationINTRODUCTIONByconventionalmethodofthecrank-and-rockerdesign,itisverydifficulttorealizetheoptimalcombinationbetweenthevariousparametersforoptimaltransmission.Thefigure-tabledesignmethodintroducedinthispapercanhelpachievethisgoal.Withgivenconditions,wecan,byonlyconsultingthedesigningfiguresandtables,gettherelationsbetweeneveryparameterandanotherofthedesignedcrank-and-rockermechanism.Thustheoptimaltransmissioncanberealized.Theconcerneddesigningtheoryandmethod,aswellastherealcasesofitsapplicationwillbeintroducedlaterrespectively.1ESTABLISHMENTOFDIAGRAMFOROPTIMALTRANSMISSIONDESIGNItisalwaysoneofthemostimportantindexesthatdesignerspursuetoimprovetheefficiencyandpropertyofthetransmission.Thecrank-and-rockermechanismiswidelyusedinthemechanicaltransmission.Howtoimproveworkabilityandreduceunnecessarypowerlossesisdirectlyrelatedtothecoefficientoftravelspeedvariation,theoscillatingangleoftherockerandtheratioofthecrankandrocker.Thereasonablecombinationoftheseparameterstakesanimportanteffectontheefficiencyandpropertyofthemechanism,whichmainlyindicatesintheevaluationoftheminimumtransmissionangle.Theaimrealizingtheoptimaltransmissionofthemechanismishowtofindthemaximumoftheminimumtransmissionangle.Thedesignparametersarereasonablycombinedbythemethodoflesseningconstraintsgraduallyandoptimizingseparately.Consequently,thecompleteconstraintfieldrealizingtheoptimaltransmissionisestablished.Thefollowingstepsaretakenintheusualdesignmethod.Firstly,theinitialvaluesofthelengthofrocker3landtheoscillatingangleofrockeraregiven.ThenthevalueofthecoefficientoftravelspeedvariationKischoseninthepermittedrange.Meanwhile,thecoordinateofthefixedhingeofcrankApossiblyrealizediscalculatedcorrespondingtovalueK.1.1LengthofbarsofcrankandrockermechanismAsshowninFig.1,leftarcGC2isthepermittedfieldofpointA.ThecoordinatesofpointAarechosenbysmallstepfrompoint2CtopointG.ThecoordinatesofpointAare02hyycA(1)22AAyRx(2)where0h,thestep,isincreasedbysmallincrementwithinrange(0,H).Ifthesmallerthechosenstepis,thehigherthecomputationalprecisionwillbe.Ristheradiusofthedesigncircle.disthedistancefrom2CtoG.2cos)2cos(22cos33lRld(3)Calculatingthelengthofarc1ACand2AC,thelengthofthebarsofthemechanismcorrespondingtopointAisobtained1,2.1.2MinimumtransmissionangleminMinimumtransmissionanglemin(seeFig.2)isdeterminedbytheequations3322142322min2)(cosllllll(4)322142322max2)(cosllllll(5)maxmin180(6)where1lLengthofcrank(mm)2lLengthofconnectingbar(mm)3lLengthofrocker(mm)4lLengthofmachineframe(mm)Firstly,wechooseminimumcomparingminwithmin.Andthenwerecordallvaluesofmingreaterthanorequalto40andchoosethemaximumofthem.Secondly,wefindthemaximumofmincorrespondingtoanyoscillatinganglewhichischosenbysmallstepinthepermittedrange(maximumofminisdifferentoscillatingangleandthecoefficientoftravelspeedvariationK).Finally,wechangethelengthofrocker3lbysmallstepsimilarly.Thuswemayobtainthemaximumofmincorrespondingtothedifferentlengthofbars,differentoscillatingangleandthecoefficientoftravelspeedvariationK.Fig.3isaccomplishedfromTableforthepurposeofdiagramdesign.