外文翻译-研究利用差动齿轮系实现机械混合压力

中文4340字出处：ScienceinChinaSeriesE:TechnologicalSciencesFebruary2007,

Volume50,

Issue1,

pp69-80StudyofutilizingdifferentialgeartraintoachievehybridmechanismofmechanicalpressHEYuPeng1†,ZHAOShengDun2,ZOUJun2&ZHANGZhiYuan21SchoolofMechanicalEngineering,NanjingUniversityofScience&Technology,Nanjing210094,China;2SchoolofMechanicalEngineering,Xi’anJiaotongUniversity,Xi’an710049,ChinaTheproblemsofhybridinputofmechanicalpressarestudiedinthispaper,withdifferentialgeartrainastransmissionmechanism.Itisproposedthat“adjustable-speedamplitude”or“differential-speedratio”istheimportantparametersforthehybridinputmechanism.Itnotonlydefinestheamplitudeoftheadjustablespeed,butalsodeterminestheratioofthepoweroftheservomotortothepoweroftheconventionalmotor.Thecalculatingequationsoftheratiooftransmissioninallaxes,thepoweroftwomotors,andtheworkingloaddistributionarededuced.Thetwokindsofdrivingschemesareputforwardthattheservomotorandtheconventionalmotorsimultaneouslydriveandtheservomotorandtheconventionalmotorseparatelydrive.Thecalculatingresultsdemonstratethatthelatterschemecanusemuchlowerpoweroftheservomotor,sothisschememakesmanufactureandusecostmuchlower.Thelatterschemeproposesafeasiblewaytoapplythehybridmechanismofmechanicalpressinpracticeengineering.mechanicalpress,hybridmechanism,differentialgeartrain,adjustable-speed1IntroductionAtpresenttherearemanyresearchpapersaboutthehybridmechanismofmechanicalpress,andithasbecomeahotresearchtopic.Thehybridmechanismisamechanismwith2-degree-offreedom(alsocalleddifferentialspeedmechanism),andwhentwoindependentmotionsareinputatthesametime,theoutputthatcansatisfysomemotionrequirementsisobtainedthroughthemotioncompositionofthemechanism.Thehybridmechanismisalsocalledcontrollablemechanism,orhybridmachine.Thepurposeofresearchonhybridmechanismofmechanicalpressisusingconventionalmotorwithbigpowercarryingflywheeltofinishstampingworkpieces;andusesser—vomotorwithlowpowertoadjustthesliderspeed.Theadvantagesofthehybridmechanismappliedinthemechanicalpressarethatitnotonlycanreducemuchlowermanufacturingcostthanservopress,butalsohasaflexibleworkingvelocityofslider[1].Sothemechanicalpressofhybridmechanismarousesmanyresearchers’interestinworkingonit;andthesestudiesaremainlyfocusedonthemulti-barhybridmechanism.DuandGuo[1,2]havecomprehensivelydiscussedtheseven-barhybridmechanismofmechanicalpress,includingthefeasibleconditionsofcompositionofthelinkagemechanism,theslidermotionanalysis,andthetorqueandpowerdistributionbetweenthetwomotorsaswellastheoptimaldesign.Thetrajectoryplanningbasedonpolynomialinterpolationisalsoinvestigated,andthecomputersimulationshowsthattheresultisindeedattractive.Inaddition,Meng[3]hasalsoinvestigatedthekinematicalanalysisoftheseven-barmechanism,andtheoptimaldesignhasbeencompletedbasedontheminimumpoweroftheservomotormotor,andMenghasproposedthatthehybridmechanismisaresearchdirectionofthemechanicalpress.Tokuz[4]firstputforwardofthehybridmechanismandanalyzedthevelocitysynthesisbyusingthedifferentialgeartrain.Hisexperimentconfirmedthefeasibilityofhisconception.Theconceptsoftheadjustable-speedamplitudeanddifferential-speedratioarenotmentionedintheirworks,andtherelationshipbetweenthevelocityvariationandthepowerofthetwomotorswerenotclearlygiven[5―8].Buttheseconceptsareveryimportantandabsolutelynecessaryforthehybridmechanismtoselectthetwomotors’poweranddeterminetheworkingloaddistributionbetweenconventionalmotorandtheservomotor.Inrefs.[1―3]theyusedlinkagemechanismtoimplementthehybridinputofmechanicalpress.Themethodisverycomplexbecausethechangeofthelengthandpositionoftheeachbarinlinkagemechanismwillhaveaneffectonthemotionoftheslideofthemechanicalpress.Sosomeprincipalproblemsareusuallyignoredinresearchhybridmechanismcourse,andtheresearchresultsdonnotalwayscoincidewiththepracticeengineeringconditions[9―11].Thegeardifferentialtrainhastwofreedoms,andtheratiosoftransmissionbetweenarbitrarytwoaxesareaconstant.Inordertosimplifythemechanicalmodelandmaketheproblemsmuchprojected,thedifferentialgeartrainisusedastransmissionmechanismtostudythehybridproblemsofthemechanicalpressinthispaper.Thispaperaddressestherelationshipbetweentheadjustable-speedamplitudeandthepowerofthetwomotors,theworkingloaddistributionbetweenthetwomotors,andputsforwardtwodriveschemesoftheconventionalmotorandtheservomotorsimultaneouslyworking,andtwomotorsseparatelyworking.Withthe200-tonmechanicalpressastheengineeringbackground,adrivesystemofthehybridmechanismofthemechanicalpressisdesigned,andthefeasibilityofthetwodriveschemesinmechanicalpressisanalyzed.2TheprincipleofthehybridmechanismTheworkingprincipleofthehybridmechanismofthemechanicalpresswithdifferentialgeartrainisillustratedinFigure1.Thesystemconsistsofconventionalmotor(alsocalledACmachinewithconstantspeed),servomotor,reducingunitI,reducingunitII,differentialgeartrain,andcrankslidemechanism.Theoutputaxisofthedifferentialgeartrainisconnectedwiththecrankshaftofthecrankslidemechanism.OneofthetwoinputaxeslinkstheconventionalmotorthroughthereducingunitІ;theotherinputaxislinkstheservomotorthroughthereducingunitII.Thereforethemotionofthecrankshaftiscompletelycontrolledbythemotionsoftheconventionalmotorandtheservomotor.ThereducingunitІandthereducingunitIIarerespectivelyinstalledbetweenthetwomotorsandthedifferentialgearunitinthewayofserialinordertobearapartofreducingvelocitytaskofthealltransmissionsystem,becausetoobigdriveratioofthedifferentialgeartrainwillmakeitsdrivingefficiencydecreased.Theangularvelocityoftheconventionalmotorisconstant,soitspriceischeaper.Theangularvelocityoftheservomotorisadjustable,soitspriceisexpensive.Inthesystemofthehybridmechanismtheconstantspeedoftheoutputaxisisprovidedbyhighpowerconventionalmotor;andtheservomotorprovidesitsadjustablespeed.Therefore,inthisway,itnotonlymakestheoutputmotionofthecrankshaftofthemechanicalpressflexible,butalsoavoidsusinghighpowerservomotor.Henceitcouldsaveboththemachinemanufacturingcostsandthemachineoperatingcosts.Figure1Workingprincipleofhybridmechanismofdifferentialgeartrain.3ThevelocitycharacteristicsofthemechanicalpressslideTheworkofthemechanicalpresspresentstheregularityoftheperiodicchange[12].ThedisplacementandvelocitychangesofthemechanicalpressslideinanidealworkcirculationareillustratedintheFigure2.Theslidestartstomovefromtopdeadcentertotheworkingstartpointathighvelocity(calledquickfeedingstage).Whentheslideofmechanicalpressapproachestheworkingpoint,itshighvelocityisshiftedtoslowvelocityandthenitbeginstostampworkpieceatlowvelocity(calledlowworkingstage).Thelowvelocityoftheslideistoavoidgreatimpactonthedie,andbenefittheplasticshapingoftheworkpiece.Aftertheslidefinishesthestampingworkandreachesthebottomdeadcenter,theslidecomesbackathighvelocityandstopsatthetopdeadcenter(calledquickbackstage).Hence,themotionvelocityofthemechanicalpressslidecanbedividedthreekinds:highdownvelocityV1,slowworkingvelocityV2,andhighbackvelocityV3.ThevelocityV1andvelocityV3shouldbeaspossibleashighandthevelocityV2shouldbeslowandflexibleinordertoensurehighworkingtimesofthemechanicalpressperminuteandsatisfytherequirementsofdifferenttechnologies.Actuallythemechanicalpressonlyworksinaveryshortcoursebeforethebottomdeadcenter,andintheothercoursesitdoesnotdoworktotheworkpiece.4Thenomenclaturesandequationsofthehybridmechanism4.1TherelationshipoftheangularvelocityinallaxesTherearethreeexternalaxesinthedifferentialgeartrainasillustratedinFigure1.Inordertoconvenientlyexpresstherelationshipofthethreeaxes,theaxisconnectedwiththeconventionalmotoriscalledaxis1,theaxisconnectedwithservomotoriscalledaxis2,andtheaxisconnectedwithcrankshaftiscalledaxis0.Theangularvelocitiesofthethreeaxesarerespectivelyexpressedasn1,n2andn0.ThetorquesofthethreeaxesarerespectivelyexpressedasM1,M2andM0.Becausetherearetwofreedomsinthedifferentialgeartrain,onlythethirdaxisisfixed,suchthatthedriveratiooftheothertwoaxescanbedetermined.Sotherelationshipsofdriveratioandangularvelocityofthethreeaxesneedtobeexpressedasthecharacterwithsuperscriptandsubscript.Figure2Idealdisplacementcureoftheslide.4.1.1Theconventionalmotor’sinfluenceontheoutputmotion.Whentheservomotorstops,n2=0,onlytheangularvelocityoftheconventionalmotoraffectstheoutputangularvelocityn0.4.1.2Theservomotor’sinfluenceontheoutputmotion.Whentheconventionalmotorstops,n1=0,onlytheangularvelocityoftheservomotoraffectstheoutputangularvelocityn0,where1n0representsaxis0angularvelocity,and1i20representstotaldriveratiofromaxis2toaxis0includingdifferentialgeartrainandreducingunitIIwhenaxis1(servomotoraxis)isfixed.4.1.3Theconventionalmotor’sandservomotor’sinfluenceontheoutputmotion.Whentheconventionalmotorandtheservomotorrunatthesametimethroughthecompositionofthedifferentialgeartrain,theoutputvelocitycanbeexpressedas.Becausetheservomotorcanrunatarbitraryangularvelocitybetweenthezeroandspecificvelocityinbothpositiveandnegativedirections,n2canbeexpressedas.whereKistheratiooftheactualangularvelocitytothespecificangularvelocityoftheservomotor;thevalueisarbitrarybetween−1and+1,includingzero.n2eisthespecificangularvelocityoftheservomotor.4.2Adjustable-speedamplitudeanddifferential-speedratio4.2.1Adjustable-speedamplitude.Inordertocorrectlydenotethevariablevelocityofthedifferentialgeartrainofthehybridmechanism,theconceptofadjustable-speedamplitudeisintroduced.AsshowninFigure1,adjustable-speedamplitudeistheratio(orpercentage)ofabsolutevalueofupanddownadjustableamounttothebasespeed.Inthedifferentialgeartrainofthehybridmechanism,theadjustable-speedamplitudeequalstheratiovalueofaxis0outputspeedofoperatingasingleservomotoratthespecificspeedtoaxis0outputspeedofoperatingasingleconventionalmotor[13].Inthedifferentialgeartrainofthehybridmechanism,theadjustable-speedamplitudeisthemostbasicandthemostimportanttechnologyparameter.Itnotonlydeterminesthematchingrelationshipofthespeedofthetwoinputaxes,butalsodecidesthematchingrelationshipoftheinstalledcapacityoftheservomotorandtheconventionalmotor4.2.2Differential-speedratio.Thedifferential-speedratioisusuallyusedtoexpressadjustablespeedtechnologyperformanceinthedifferentialgeartrain.Itisanimportanttechnologyparameterofthedifferentialeffectinthedifferentialsystem.Thedifferential-speedratioequalsthereciprocalvalueoftheadjustable-speedamplitude.ItcanbeexpressedasAccordingtothefactthattheangularvelocityisininverseproportiontoitstorqueandthatthesameloadisdrivenbyconventionalmotorandservomotor,anequationexpressedwiththepowersofthetwomotorscanbededuced,whereP1isthepoweroftheconventionalmotor,P1=M1n1.P2isthepoweroftheservomotor,P2=M2n2e.4.3TheworkingloadpowerdistributionSupposingthattheworkingloadpowerofthemechanicalpressisP0,thepowerrelationshipbetweentheconventionalmotor,theservomotorandworkingloadcanbeexpressedasbelow:Figure3Physicalsenseoftheadjustable-speedamplitude.Fromeqs.(9)―(11),theoutputpowersoftheconventionalmotorandtheservomotoraredeterminedbythevalueoffactorK,whichisactuallyequaltothechangeratioofangularvelocityoftheservomotor.Hencewhentheoutputangularvelocityrunsindifferentworkingregion,theratioofbearingloadofthetwomotorsisdifferent,too.4.3.1Theoutputaxisrunningatthebasicspeed.Whentheoutputangularvelocityoftheservomotorequalszero,thatis,K=0,P2=0,fromeq.(9),wehave.Heretheconventionalmotorbearsalltheloadingpower.4.3.2Theoutputaxisrunningintheincreasingspeedregion.Theservomotorrunsinthepositivedirection,0≤K≤1,andbothP1andP2arepositivevalues,soboththeconventionalmotorandtheservomotorbearapartoftheworkingload.Thustheconventionalmotorbears90.9%―100%workingloadandtheservomotorbearsonly0―9.1%workingload.Thevalueoftheadjustable-speedandthedifferential-speedratiodeter-minetheloaddistributionbetweenthetwomotors.4.3.3Theoutputaxisrunninginthedecreasingspeedregion.Inthedecreasingspeedregion,theservomotorrunsinnegativedirection,andtherangevalueofKis−1≤K≤0.Byeqs.(9)and(10),theP1ispositive,andtheP2isnegative.Thenegativevalueoftheservomotorpowershowsthattheservomotorpowerisalreadytheworkingresistance.Hencetheconventionalmotorisnotonlydoingworktotheworkingload,butalsodoingworktotheservomotorpower,Whentheangularspeedisintheregion0―n2e,theloadoftheconventionalmotorisThuswhentheoutputangularspeedisinthedecreasingregion,theconventionalmotorconsumesmoreenergythanintheotherregions.Thedecreaseoftheoutputspeedisatthepriceofconsumingtheservomotorinputpower.Inordertosaveenergy,theoutputangularspeedshouldavoidorreducerunninginthedecreasingregion.4.4ThetwodriveschemesofthehybridmechanismofthemechanicalpressAccordingtoeq.(3),theoutputangularvelocityofthehybridmechanismisequaltothereducedvalueoftheirsumoftheangularvelocitiesofboththeconventionalmotorandtheservomotor.AsshowninFigure1,theoutputangularvelocityofthedifferentialgeartrainisconnectedwiththecrankaxisofthemechanicalpress,sothetwoaxeshavethesameangularvelocity.Wheneitheroftheconventionalmotorortheservomotorisdriven,orwhenbothofthemaredriven,thedifferentangularvelocityofthecrankshaftofthemechanicalpresscanbeobtained.Therefore,twokindsoftheschemesofthehybridmechanismofthemechanicalpressareproposed:(i)theconventionalmotorandtheservomotoraresimultaneouslydriven;and(ii)theconventionalmotorandtheservomotorareseparatelydriven.4.4.1Theconventionalmotorandtheservomotorbeingsimultaneouslydriven.Thisschemeshowsthattheangularvelocityofthecrankshaftofthemechanicalpressiscomposedoftheangularvelocityoftheconventionalmotorasthebasicspeedandtheangularvelocityoftheservomotorastheadjustablespeed(Figure3).Theangularvelocityandthepowerscanbecalculatedbyusingeqs.(1)―(18).4.4.2Theconventionalmotorandtheservomotorbeingseparatelydriven.Thisschemeshowsthatonlyonemotorisdriveninthehybridinputcourseandatthesametimeanothermotorisbraked,i.e.whenthecrankshaftisindifferentialrunningstage,theconventionalmotorandtheservomotorareseparatelyoperated;thusthedifferentangularvelocityofthecrankshaftcanbeobtained.Theflexiblelowspeedoperation.Whentheconventionalmotorisbrakedandtheservomotorisoperated,n1=0，thebelowequationcanbeobtainedfromeq.(5)Because−1≤K≤+1,theoutputangularvelocityofthecrankshaftisadjustableandthecrankshafthastworotatingdirections;thereforeitisflexible.Abigvalueofthedriveratio1i20canbedesigned,soaverysmalloutputangularvelocity1n0canbeachieved.Henceinthiscoursetheoutputangularvelocityisflexibleandlow.Whentheservomotorisbrakedandtheconventionalmotorisoperated,n2=0,fromeq.(5),wehave.Crankshafthastworotatingdirections;thereforeitisflexible.Figure4Physicalsenseofthecomparisonofthetwooutputangularspeed.Becausedriveratios2i10and1i20areindependentofeachother,andtheoperationandtheservomotoroperationoftheconventionalmotorsareindependentofeachothertoo,thevaluesofthetwodriveratioscanbeassignedaverydifferentvalue(oneisverysmall,andtheotherisverybig),sothetwooutputangularvelocitiesmaydiffergreatly.Sodoingcansatisfythemotionrequirementsofthemechanicalpressslideindifferentstages.ThephysicalsenseofcomparisonofthetwooutputangularspeedisillustratedasinFigure4.5ConclusionAccordingtothevelocitycharacteristicsofthemechanicalpress,thedifferentialgeartrainisappliedinthehybridmechanismofthemechanicalpress.Throughtheaboveanalysisandcalculation,thefollowingconclusionscanbereached:(1)Theadjustable-speedamplitudeanddifferential-speedratioareimportantparametersofthehybridmechanism.Theyarenotonlytheratiooftheadjustablespeedtothebasicspeed,butalsotheratioofthepoweroftheservomotortothepoweroftheconventionalmotor.(2)Withtheschemeoftheconventionalmotorandtheservomotorbeingsimultaneouslydriven,thepowerofthetwomotorshastobeassignedhighvalueinordertosatisfythevelocityrequirementsofthemechanicalpress.Sodoingincreasesthemanufacturingcostandtheoperationcostofthemechanicalpress,andthereforeisvaluelessinpracticalapplication.(3)Withtheschemeoftheconventionalmotorandtheservomotorbeingseparatelydriven,thepoweroftheservomotorcanbeassignedlowvalueinordertosatisfythevelocityrequirementsofthemechanicalpress.Sodoingdecreasesthemanufacturingcostandtheoperationcostofthemechanicalpress.Therefore,thisschemeproposesafeasiblewayinpracticalindustrialengineering.研究利用差动齿轮系实现机械混合压力本文对机械压力混合输入的问题进行了研究，用差动轮系作为传动机构。它建议将“调速幅度”或“差动速比”作为重要参数混合投入机械研究中。它不仅规定了可调节幅度速度，而且还决定了伺服电动机功率比的传统电机。所有传动轴计算的传输功率，两个电机的功率和工作负载的分布得到了推断结果。它提出了伺服电机和传统电机同时驱动，伺服电机和传统电机单独驱动两种驱动方案。计算结果表明后者的方案能比伺服电机使用更低的功率，因此这种方案能使得制造和使用成本低得多。后一个方案提出了一个可行的途径在实际工程中来使用混合机械压力。机械压力，混合机制，差动轮系，调速1、引言目前有许多关于机械压力的混合机制的研究报道，并且已经成为一个热门的研究话题。混合动力机制是一种有2个自由度的机制（也称为差速机制），当两个独立的运动同时输入时，输出的运动能够满足一些运动要求，这些要求通过机械的运动组成来获得的。混合动力机制也可称为可控机制，或者称作混合机器。研究机械压力机的混合机械的目的是使用大功率常规电机利用飞轮来完成工件的冲压；并使用低功率的伺服电机来调整滑块速度。应用在机械压力中的混合机制的优势在于它不仅可以比伺服压力机降低更多的制造成本，而且还有一个灵活的工作速度滑块。所以混合动力机械压力机在机制上的工作引起了许多研究者的兴趣；并且这些研究主要集中在多杆混合机械中。杜和郭已经全面讨论了七杆的机械压力机的混合机制，包括组成连杆机构的可行条件，滑块机构的动力分析，和两台电机之间转矩和功率的分配以及它们之间的优化设计。基于多项式的轨迹规划也需要调查，且计算机模拟表明结果的确吸引人。此外，孟也调查了七杆机构的运动学分析，基于最低功率的伺服电机的优化设计已经完成，然后孟建议混合机制是机械压力机的研究方向。Tokuz首次提出了混合机构并且使用差动齿轮系分析了合成速度。他的实验证实了他的理论的可行性。调速幅度和差速比的概念在他们的作品中没有提到，并且两电机的速度变化和功率之间的关系也没有清楚的给出。但是这些概念对混合动力机械选择两个电机的功率、决定传统电机和伺服电机之间的工作负载分配非常重要而且是绝对必要的。在参考文献[1-3]中他们使用连杆机构来实施机械压力机的混合输入。这种方法相当复杂，因为连杆机构每根连杆的长度和位置的改变会对机械压力机的滑块运动产生影响。所以一些主要的问题在混合机械的课程研究中常常被忽略，而且研究结果不总是和实际工程条件相符合。差动齿轮系有两个自由度，并且任意两轴之间的传动比是一个常数。为了简化机械模型并使得问题更加透明，在这篇文章中差速齿轮系常作为传动机构来研究机械压力机的混合问题。这篇文章讨论了两电机调速幅度和功率之间的关系，两电机之间的工作负载分配，并且提出了传统电机和伺服电机同时工作、分开工作的两种驱动方案。随着200吨的机械压力机作为工程背景，机械压力机的混合动力驱动系统已设计出来，并且在机械压力机中的两种驱动方案的可行性也已得到了分析。2、混合型机械的主要原则带有差动齿轮系的混合机械压力机的工作准则在图1中得到了说明。系统由传统电机（也叫作恒定速度的AC机器），伺服电机，减速器1，减速器2，差动轮系和曲柄滑块机构组成。差动轮系的输出轴由曲柄滑块机构的曲柄轴连接而成。两根输入轴中的一根轴通过减速器1和传统电机相连；另外一根输入轴通过减速器2和伺服电机相连。因此曲柄轴的运动完全由传统电机和伺服电机的运动来控制。减速器1和减速器2以串行方式安装在两个电机和差速齿轮系单元之间目的是为了承担所有传动系统的一部分减速任务，因为太大的差动齿轮系传动比会使得传动效率下降。传统电机的角速度是一个常数，所以它的价格更便宜。伺服电机的角速度是可调的，所以它的价格昂贵。混合动力机构系统中的输出轴的恒定转速由大功率的传统电机提供；而伺服电机提供可调的速度。因此，用这种方式，不仅使得机械压力机的曲柄轴的输出运动灵活可变，而且还避免使用大功率的伺服电机。因此它既可以节约机器制造代价又可以节约机器运转成本。图1差速齿轮系的混合机构工作准则3、机械压力机滑块的速度特征机械压力机的运转体现了周期性的变化规律。机械压力机的滑块在理想的工作条件下的位置和速度变化如图2所示。滑块以很大的速度（称作快速进给阶段）从顶部死角中心移到工作起点。当机械压力机的滑块接近工作起点时，它的速度会从高速变成低速，然后以低速（称作低速进给阶段）冲压工件。低速的滑块是为了避免对模具产生重大的影响，有益于塑料工件的成型。在滑块完成冲压工件并达到工件死角中心的底部时，滑块会以高速返回并最终停在死角中心的顶部（称作快速返回阶段）。因此，机械压力机的滑块的移动速度可以分为三种情况：快速下降速度V1，缓慢工作速度V2，和快速返回速度V3。速度V1和V3应该尽可能一样快，速度V2应该缓慢、灵活，目的是为了确保机械压力机每分钟的工作次数并能满足不同技术的要求。事实上机械压力机在到达死角中心的底部之前仅以一个很短的行程工作，而在其他行程中对工件来说是不工作的。4、混合机械的术语和方程4.1所有轴的角速度的关系如图1所示在差动齿轮轮系中有三个外部轴。为了方便的表达三个轴之间的关系，和常规电机连接的轴叫轴1，和伺服电机连接的轴叫轴2，和曲轴连接的轴叫轴0。三根轴的