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SCIENCEINCHINASERIESETECHNOLOGICALSCIENCES2007SCIENCEINCHINAPRESSSPRINGERVERLAGSTUDYOFUTILIZINGDIFFERENTIALGEARTRAINTOACHIEVEHYBRIDMECHANISMOFMECHANICALPRESSHEYUPENG1†,ZHAOSHENGDUN2,ZOUJUN2ZHANGZHIYUAN21SCHOOLOFMECHANICALENGINEERING,NANJINGUNIVERSITYOFSCIENCETECHNOLOGY,NANJING210094,CHINA；2SCHOOLOFMECHANICALENGINEERING,XI’ANJIAOTONGUNIVERSITY,XI’AN710049,CHINATHEPROBLEMSOFHYBRIDINPUTOFMECHANICALPRESSARESTUDIEDINTHISPAPER,WITHDIFFERENTIALGEARTRAINASTRANSMISSIONMECHANISMITISPROPOSEDTHAT“ADJUSTABLESPEEDAMPLITUDE”OR“DIFFERENTIALSPEEDRATIO”ISTHEIMPORTANTPARAMETERSFORTHEHYBRIDINPUTMECHANISMITNOTONLYDEFINESTHEAMPLITUDEOFTHEADJUSTABLESPEED,BUTALSODETERMINESTHERATIOOFTHEPOWEROFTHESERVOMOTORTOTHEPOWEROFTHECONVENTIONALMOTORTHECALCULATINGEQUATIONSOFTHERATIOOFTRANSMISSIONINALLAXES,THEPOWEROFTWOMOTORS,ANDTHEWORKINGLOADDISTRIBUTIONAREDEDUCEDTHETWOKINDSOFDRIVINGSCHEMESAREPUTFORWARDTHATTHESERVOMOTORANDTHECONVENTIONALMOTORSIMULTANEOUSLYDRIVEANDTHESERVOMOTORANDTHECONVENTIONALMOTORSEPARATELYDRIVETHECALCULATINGRESULTSDEMONSTRATETHATTHELATTERSCHEMECANUSEMUCHLOWERPOWEROFTHESERVOMOTOR,SOTHISSCHEMEMAKESMANUFACTUREANDUSECOSTMUCHLOWERTHELATTERSCHEMEPROPOSESAFEASIBLEWAYTOAPPLYTHEHYBRIDMECHANISMOFMECHANICALPRESSINPRACTICEENGINEERINGMECHANICALPRESS,HYBRIDMECHANISM,DIFFERENTIALGEARTRAIN,ADJUSTABLESPEED1INTRODUCTIONATPRESENTTHEREAREMANYRESEARCHPAPERSABOUTTHEHYBRIDMECHANISMOFMECHANICALPRESS,ANDITHASBECOMEAHOTRESEARCHTOPICTHEHYBRIDMECHANISMISAMECHANISMWITH2DEGREEOFFREEDOMALSOCALLEDDIFFERENTIALSPEEDMECHANISM,ANDWHENTWOINDEPENDENTMOTIONSAREINPUTATTHESAMETIME,THEOUTPUTTHATCANSATISFYSOMEMOTIONREQUIREMENTSISOBTAINEDTHROUGHTHEMOTIONCOMPOSITIONOFTHEMECHANISMTHEHYBRIDMECHANISMISALSOCALLEDCONTROLLABLEMECHANISM,ORHYBRIDMACHINETHEPURPOSEOFRESEARCHONHYBRIDMECHANISMOFMECHANICALPRESSISUSINGCONVENTIONALMOTORWITHBIGPOWERCARRYINGFLYWHEELTOFINISHSTAMPINGWORKPIECES；ANDUSESSERVOMOTORWITHLOWPOWERTOADJUSTTHESLIDERSPEEDTHEADVANTAGESOFTHEHYBRIDMECHANISMAPPLIEDINTHEMECHANICALPRESSARETHATITNOTONLYCANREDUCEMUCHLOWERMANUFACTURINGCOSTTHANSERVOPRESS,BUTALSOHASAFLEXIBLEWORKINGVELOCITYOFSLIDER1SOTHEMECHANICALPRESSOFHYBRIDMECHANISMAROUSESMANYRESEARCHERS’INTERESTINWORKINGONIT；ANDTHESESTUDIESAREMAINLYFOCUSEDONTHEMULTIBARHYBRIDMECHANISMDUANDGUO1,2HAVECOMPREHENSIVELYDISCUSSEDTHESEVENBARHYBRIDMECHANISMOFMECHANICALPRESS,INCLUDINGTHEFEASIBLECONDITIONSOFCOMPOSITIONOFTHELINKAGEMECHANISM,THESLIDERMOTIONANALYSIS,ANDTHETORQUEANDPOWERDISTRIBUTIONBETWEENTHETWOMOTORSASWELLASTHEOPTIMALDESIGNTHETRAJECTORYPLANNINGBASEDONPOLYNOMIALINTERPOLATIONISALSOINVESTIGATED,ANDTHECOMPUTERSIMULATIONSHOWSTHATTHERESULTISINDEEDATTRACTIVEINADDITION,MENG3HASALSOINVESTIGATEDTHEKINEMATICALANALYSISOFTHESEVENBARMECHANISM,ANDTHEOPTIMALDESIGNHASBEENCOMPLETEDBASEDONTHEMINIMUMPOWEROFTHESERVOMOTORMOTOR,ANDMENGHASPROPOSEDTHATTHEHYBRIDMECHANISMISARESEARCHDIRECTIONOFTHEMECHANICALPRESSTOKUZ4FIRSTPUTFORWARDOFTHEHYBRIDMECHANISMANDANALYZEDTHEVELOCITYSYNTHESISBYUSINGTHEDIFFERENTIALGEARTRAINHISEXPERIMENTCONFIRMEDTHEFEASIBILITYOFHISCONCEPTIONTHECONCEPTSOFTHEADJUSTABLESPEEDAMPLITUDEANDDIFFERENTIALSPEEDRATIOARENOTMENTIONEDINTHEIRWORKS,ANDTHERELATIONSHIPBETWEENTHEVELOCITYVARIATIONANDTHEPOWEROFTHETWOMOTORSWERENOTCLEARLYGIVEN58BUTTHESECONCEPTSAREVERYIMPORTANTANDABSOLUTELYNECESSARYFORTHEHYBRIDMECHANISMTOSELECTTHETWOMOTORS’POWERANDDETERMINETHEWORKINGLOADDISTRIBUTIONBETWEENCONVENTIONALMOTORANDTHESERVOMOTORINREFS13THEYUSEDLINKAGEMECHANISMTOIMPLEMENTTHEHYBRIDINPUTOFMECHANICALPRESSTHEMETHODISVERYCOMPLEXBECAUSETHECHANGEOFTHELENGTHANDPOSITIONOFTHEEACHBARINLINKAGEMECHANISMWILLHAVEANEFFECTONTHEMOTIONOFTHESLIDEOFTHEMECHANICALPRESSSOSOMEPRINCIPALPROBLEMSAREUSUALLYIGNOREDINRESEARCHHYBRIDMECHANISMCOURSE,ANDTHERESEARCHRESULTSDONNOTALWAYSCOINCIDEWITHTHEPRACTICEENGINEERINGCONDITIONS911THEGEARDIFFERENTIALTRAINHASTWOFREEDOMS,ANDTHERATIOSOFTRANSMISSIONBETWEENARBITRARYTWOAXESAREACONSTANTINORDERTOSIMPLIFYTHEMECHANICALMODELANDMAKETHEPROBLEMSMUCHPROJECTED,THEDIFFERENTIALGEARTRAINISUSEDASTRANSMISSIONMECHANISMTOSTUDYTHEHYBRIDPROBLEMSOFTHEMECHANICALPRESSINTHISPAPERTHISPAPERADDRESSESTHERELATIONSHIPBETWEENTHEADJUSTABLESPEEDAMPLITUDEANDTHEPOWEROFTHETWOMOTORS,THEWORKINGLOADDISTRIBUTIONBETWEENTHETWOMOTORS,ANDPUTSFORWARDTWODRIVESCHEMESOFTHECONVENTIONALMOTORANDTHESERVOMOTORSIMULTANEOUSLYWORKING,ANDTWOMOTORSSEPARATELYWORKINGWITHTHE200TONMECHANICALPRESSASTHEENGINEERINGBACKGROUND,ADRIVESYSTEMOFTHEHYBRIDMECHANISMOFTHEMECHANICALPRESSISDESIGNED,ANDTHEFEASIBILITYOFTHETWODRIVESCHEMESINMECHANICALPRESSISANALYZED2THEPRINCIPLEOFTHEHYBRIDMECHANISMTHEWORKINGPRINCIPLEOFTHEHYBRIDMECHANISMOFTHEMECHANICALPRESSWITHDIFFERENTIALGEARTRAINISILLUSTRATEDINFIGURE1THESYSTEMCONSISTSOFCONVENTIONALMOTORALSOCALLEDACMACHINEWITHCONSTANTSPEED,SERVOMOTOR,REDUCINGUNITI,REDUCINGUNITII,DIFFERENTIALGEARTRAIN,ANDCRANKSLIDEMECHANISMTHEOUTPUTAXISOFTHEDIFFERENTIALGEARTRAINISCONNECTEDWITHTHECRANKSHAFTOFTHECRANKSLIDEMECHANISMONEOFTHETWOINPUTAXESLINKSTHECONVENTIONALMOTORTHROUGHTHEREDUCINGUNITІ；THEOTHERINPUTAXISLINKSTHESERVOMOTORTHROUGHTHEREDUCINGUNITIITHEREFORETHEMOTIONOFTHECRANKSHAFTISCOMPLETELYCONTROLLEDBYTHEMOTIONSOFTHECONVENTIONALMOTORANDTHESERVOMOTORTHEREDUCINGUNITІANDTHEREDUCINGUNITIIARERESPECTIVELYINSTALLEDBETWEENTHETWOMOTORSANDTHEDIFFERENTIALGEARUNITINTHEWAYOFSERIALINORDERTOBEARAPARTOFREDUCINGVELOCITYTASKOFTHEALLTRANSMISSIONSYSTEM,BECAUSETOOBIGDRIVERATIOOFTHEDIFFERENTIALGEARTRAINWILLMAKEITSDRIVINGEFFICIENCYDECREASEDTHEANGULARVELOCITYOFTHECONVENTIONALMOTORISCONSTANT,SOITSPRICEISCHEAPERTHEANGULARVELOCITYOFTHESERVOMOTORISADJUSTABLE,SOITSPRICEISEXPENSIVEINTHESYSTEMOFTHEHYBRIDMECHANISMTHECONSTANTSPEEDOFTHEOUTPUTAXISISPROVIDEDBYHIGHPOWERCONVENTIONALMOTOR；ANDTHESERVOMOTORPROVIDESITSADJUSTABLESPEEDTHEREFORE,INTHISWAY,ITNOTONLYMAKESTHEOUTPUTMOTIONOFTHECRANKSHAFTOFTHEMECHANICALPRESSFLEXIBLE,BUTALSOAVOIDSUSINGHIGHPOWERSERVOMOTORHENCEITCOULDSAVEBOTHTHEMACHINEMANUFACTURINGCOSTSANDTHEMACHINEOPERATINGCOSTSFIGURE1WORKINGPRINCIPLEOFHYBRIDMECHANISMOFDIFFERENTIALGEARTRAIN3THEVELOCITYCHARACTERISTICSOFTHEMECHANICALPRESSSLIDETHEWORKOFTHEMECHANICALPRESSPRESENTSTHEREGULARITYOFTHEPERIODICCHANGE12THEDISPLACEMENTANDVELOCITYCHANGESOFTHEMECHANICALPRESSSLIDEINANIDEALWORKCIRCULATIONAREILLUSTRATEDINTHEFIGURE2THESLIDESTARTSTOMOVEFROMTOPDEADCENTERTOTHEWORKINGSTARTPOINTATHIGHVELOCITYCALLEDQUICKFEEDINGSTAGEWHENTHESLIDEOFMECHANICALPRESSAPPROACHESTHEWORKINGPOINT,ITSHIGHVELOCITYISSHIFTEDTOSLOWVELOCITYANDTHENITBEGINSTOSTAMPWORKPIECEATLOWVELOCITYCALLEDLOWWORKINGSTAGETHELOWVELOCITYOFTHESLIDEISTOAVOIDGREATIMPACTONTHEDIE,ANDBENEFITTHEPLASTICSHAPINGOFTHEWORKPIECEAFTERTHESLIDEFINISHESTHESTAMPINGWORKANDREACHESTHEBOTTOMDEADCENTER,THESLIDECOMESBACKATHIGHVELOCITYANDSTOPSATTHETOPDEADCENTERCALLEDQUICKBACKSTAGEHENCE,THEMOTIONVELOCITYOFTHEMECHANICALPRESSSLIDECANBEDIVIDEDTHREEKINDSHIGHDOWNVELOCITYV1,SLOWWORKINGVELOCITYV2,ANDHIGHBACKVELOCITYV3THEVELOCITYV1ANDVELOCITYV3SHOULDBEASPOSSIBLEASHIGHANDTHEVELOCITYV2SHOULDBESLOWANDFLEXIBLEINORDERTOENSUREHIGHWORKINGTIMESOFTHEMECHANICALPRESSPERMINUTEANDSATISFYTHEREQUIREMENTSOFDIFFERENTTECHNOLOGIESACTUALLYTHEMECHANICALPRESSONLYWORKSINAVERYSHORTCOURSEBEFORETHEBOTTOMDEADCENTER,ANDINTHEOTHERCOURSESITDOESNOTDOWORKTOTHEWORKPIECE4THENOMENCLATURESANDEQUATIONSOFTHEHYBRIDMECHANISM41THERELATIONSHIPOFTHEANGULARVELOCITYINALLAXESTHEREARETHREEEXTERNALAXESINTHEDIFFERENTIALGEARTRAINASILLUSTRATEDINFIGURE1INORDERTOCONVENIENTLYEXPRESSTHERELATIONSHIPOFTHETHREEAXES,THEAXISCONNECTEDWITHTHECONVENTIONALMOTORISCALLEDAXIS1,THEAXISCONNECTEDWITHSERVOMOTORISCALLEDAXIS2,ANDTHEAXISCONNECTEDWITHCRANKSHAFTISCALLEDAXIS0THEANGULARVELOCITIESOFTHETHREEAXESARERESPECTIVELYEXPRESSEDASN1,N2ANDN0THETORQUESOFTHETHREEAXESARERESPECTIVELYEXPRESSEDASM1,M2ANDM0BECAUSETHEREARETWOFREEDOMSINTHEDIFFERENTIALGEARTRAIN,ONLYTHETHIRDAXISISFIXED,SUCHTHATTHEDRIVERATIOOFTHEOTHERTWOAXESCANBEDETERMINEDSOTHERELATIONSHIPSOFDRIVERATIOANDANGULARVELOCITYOFTHETHREEAXESNEEDTOBEEXPRESSEDASTHECHARACTERWITHSUPERSCRIPTANDSUBSCRIPTFIGURE2IDEALDISPLACEMENTCUREOFTHESLIDE411THECONVENTIONALMOTOR’SINFLUENCEONTHEOUTPUTMOTIONWHENTHESERVOMOTORSTOPS,N20,ONLYTHEANGULARVELOCITYOFTHECONVENTIONALMOTORAFFECTSTHEOUTPUTANGULARVELOCITYN0412THESERVOMOTOR’SINFLUENCEONTHEOUTPUTMOTIONWHENTHECONVENTIONALMOTORSTOPS,N10,ONLYTHEANGULARVELOCITYOFTHESERVOMOTORAFFECTSTHEOUTPUTANGULARVELOCITYN0,WHERE1N0REPRESENTSAXIS0ANGULARVELOCITY,AND1I20REPRESENTSTOTALDRIVERATIOFROMAXIS2TOAXIS0INCLUDINGDIFFERENTIALGEARTRAINANDREDUCINGUNITIIWHENAXIS1SERVOMOTORAXISISFIXED413THECONVENTIONALMOTOR’SANDSERVOMOTOR’SINFLUENCEONTHEOUTPUTMOTIONWHENTHECONVENTIONALMOTORANDTHESERVOMOTORRUNATTHESAMETIMETHROUGHTHECOMPOSITIONOFTHEDIFFERENTIALGEARTRAIN,THEOUTPUTVELOCITYCANBEEXPRESSEDASBECAUSETHESERVOMOTORCANRUNATARBITRARYANGULARVELOCITYBETWEENTHEZEROANDSPECIFICVELOCITYINBOTHPOSITIVEANDNEGATIVEDIRECTIONS,N2CANBEEXPRESSEDASWHEREKISTHERATIOOFTHEACTUALANGULARVELOCITYTOTHESPECIFICANGULARVELOCITYOFTHESERVOMOTOR；THEVALUEISARBITRARYBETWEEN−1AND1,INCLUDINGZERON2EISTHESPECIFICANGULARVELOCITYOFTHESERVOMOTOR42ADJUSTABLESPEEDAMPLITUDEANDDIFFERENTIALSPEEDRATIO421ADJUSTABLESPEEDAMPLITUDEINORDERTOCORRECTLYDENOTETHEVARIABLEVELOCITYOFTHEDIFFERENTIALGEARTRAINOFTHEHYBRIDMECHANISM,THECONCEPTOFADJUSTABLESPEEDAMPLITUDEISINTRODUCEDASSHOWNINFIGURE1,ADJUSTABLESPEEDAMPLITUDEISTHERATIOORPERCENTAGEOFABSOLUTEVALUEOFUPANDDOWNADJUSTABLEAMOUNTTOTHEBASESPEEDINTHEDIFFERENTIALGEARTRAINOFTHEHYBRIDMECHANISM,THEADJUSTABLESPEEDAMPLITUDEEQUALSTHERATIOVALUEOFAXIS0OUTPUTSPEEDOFOPERATINGASINGLESERVOMOTORATTHESPECIFICSPEEDTOAXIS0OUTPUTSPEEDOFOPERATINGASINGLECONVENTIONALMOTOR13INTHEDIFFERENTIALGEARTRAINOFTHEHYBRIDMECHANISM,THEADJUSTABLESPEEDAMPLITUDEISTHEMOSTBASICANDTHEMOSTIMPORTANTTECHNOLOGYPARAMETERITNOTONLYDETERMINESTHEMATCHINGRELATIONSHIPOFTHESPEEDOFTHETWOINPUTAXES,BUTALSODECIDESTHEMATCHINGRELATIONSHIPOFTHEINSTALLEDCAPACITYOFTHESERVOMOTORANDTHECONVENTIONALMOTOR
