外文翻譯-研究利用差動齒輪系實(shí)現(xiàn)機(jī)械混合壓力

中文4340字出處：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.Oneofthetwoinputaxeslinkstheconventionalmotorthroughthereducingunit?;theotherinputaxislinkstheservomotorthroughthereducingunitII.Thereforethemotionofthecrankshaftiscompletelycontrolledbythemotionsoftheconventionalmotorandtheservomotor.Thereducingunit?andthereducingunitIIarerespectivelyinstalledbetweenthetwomotorsandthedifferentialgearunitinthewayofserialinordertobearapartofreducingvelocitytaskofthealltransmissionsystem,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.研究利用差動齒輪系實(shí)現(xiàn)機(jī)械混合壓力本文對機(jī)械壓力混合輸入的問題進(jìn)行了研究，用差動輪系作為傳動機(jī)構(gòu)。它建議將“調(diào)速幅度”或“差動速比”作為重要參數(shù)混合投入機(jī)械研究中。它不僅規(guī)定了可調(diào)節(jié)幅度速度，而且還決定了伺服電動機(jī)功率比的傳統(tǒng)電機(jī)。所有傳動軸計算的傳輸功率，兩個電機(jī)的功率和工作負(fù)載的分布得到了推斷結(jié)果。它提出了伺服電機(jī)和傳統(tǒng)電機(jī)同時驅(qū)動，伺服電機(jī)和傳統(tǒng)電機(jī)單獨(dú)驅(qū)動兩種驅(qū)動方案。計算結(jié)果表明后者的方案能比伺服電機(jī)使用更低的功率，因此這種方案能使得制造和使用成本低得多。后一個方案提出了一個可行的途徑在實(shí)際工程中來使用混合機(jī)械壓力。機(jī)械壓力，混合機(jī)制，差動輪系，調(diào)速1、引言目前有許多關(guān)于機(jī)械壓力的混合機(jī)制的研究報道，并且已經(jīng)成為一個熱門的研究話題。混合動力機(jī)制是一種有2個自由度的機(jī)制（也稱為差速機(jī)制），當(dāng)兩個獨(dú)立的運(yùn)動同時輸入時，輸出的運(yùn)動能夠滿足一些運(yùn)動要求，這些要求通過機(jī)械的運(yùn)動組成來獲得的?；旌蟿恿C(jī)制也可稱為可控機(jī)制，或者稱作混合機(jī)器。研究機(jī)械壓力機(jī)的混合機(jī)械的目的是使用大功率常規(guī)電機(jī)利用飛輪來完成工件的沖壓；并使用低功率的伺服電機(jī)來調(diào)整滑塊速度。應(yīng)用在機(jī)械壓力中的混合機(jī)制的優(yōu)勢在于它不僅可以比伺服壓力機(jī)降低更多的制造成本，而且還有一個靈活的工作速度滑塊。所以混合動力機(jī)械壓力機(jī)在機(jī)制上的工作引起了許多研究者的興趣；并且這些研究主要集中在多桿混合機(jī)械中。杜和郭已經(jīng)全面討論了七桿的機(jī)械壓力機(jī)的混合機(jī)制，包括組成連桿機(jī)構(gòu)的可行條件，滑塊機(jī)構(gòu)的動力分析，和兩臺電機(jī)之間轉(zhuǎn)矩和功率的分配以及它們之間的優(yōu)化設(shè)計?；诙囗検降能壽E規(guī)劃也需要調(diào)查，且計算機(jī)模擬表明結(jié)果的確吸引人。此外，孟也調(diào)查了七桿機(jī)構(gòu)的運(yùn)動學(xué)分析，基于最低功率的伺服電機(jī)的優(yōu)化設(shè)計已經(jīng)完成，然后孟建議混合機(jī)制是機(jī)械壓力機(jī)的研究方向。Tokuz首次提出了混合機(jī)構(gòu)并且使用差動齒輪系分析了合成速度。他的實(shí)驗證實(shí)了他的理論的可行性。調(diào)速幅度和差速比的概念在他們的作品中沒有提到，并且兩電機(jī)的速度變化和功率之間的關(guān)系也沒有清楚的給出。但是這些概念對混合動力機(jī)械選擇兩個電機(jī)的功率、決定傳統(tǒng)電機(jī)和伺服電機(jī)之間的工作負(fù)載分配非常重要而且是絕對必要的。在參考文獻(xiàn)[1-3]中他們使用連桿機(jī)構(gòu)來實(shí)施機(jī)械壓力機(jī)的混合輸入。這種方法相當(dāng)復(fù)雜，因為連桿機(jī)構(gòu)每根連桿的長度和位置的改變會對機(jī)械壓力機(jī)的滑塊運(yùn)動產(chǎn)生影響。所以一些主要的問題在混合機(jī)械的課程研究中常常被忽略，而且研究結(jié)果不總是和實(shí)際工程條件相符合。差動齒輪系有兩個自由度，并且任意兩軸之間的傳動比是一個常數(shù)。為了簡化機(jī)械模型并使得問題更加透明，在這篇文章中差速齒輪系常作為傳動機(jī)構(gòu)來研究機(jī)械壓力機(jī)的混合問題。這篇文章討論了兩電機(jī)調(diào)速幅度和功率之間的關(guān)系，兩電機(jī)之間的工作負(fù)載分配，并且提出了傳統(tǒng)電機(jī)和伺服電機(jī)同時工作、分開工作的兩種驅(qū)動方案。隨著200噸的機(jī)械壓力機(jī)作為工程背景，機(jī)械壓力機(jī)的混合動力驅(qū)動系統(tǒng)已設(shè)計出來，并且在機(jī)械壓力機(jī)中的兩種驅(qū)動方案的可行性也已得到了分析。2、混合型機(jī)械的主要原則帶有差動齒輪系的混合機(jī)械壓力機(jī)的工作準(zhǔn)則在圖1中得到了說明。系統(tǒng)由傳統(tǒng)電機(jī)（也叫作恒定速度的AC機(jī)器），伺服電機(jī)，減速器1，減速器2，差動輪系和曲柄滑塊機(jī)構(gòu)組成。差動輪系的輸出軸由曲柄滑塊機(jī)構(gòu)的曲柄軸連接而成。兩根輸入軸中的一根軸通過減速器1和傳統(tǒng)電機(jī)相連；另外一根輸入軸通過減速器2和伺服電機(jī)相連。因此曲柄軸的運(yùn)動完全由傳統(tǒng)電機(jī)和伺服電機(jī)的運(yùn)動來控制。減速器1和減速器2以串行方式安裝在兩個電機(jī)和差速齒輪系單元之間目的是為了承擔(dān)所有傳動系統(tǒng)的一部分減速任務(wù)，因為太大的差動齒輪系傳動比會使得傳動效率下降。傳統(tǒng)電機(jī)的角速度是一個常數(shù)，所以它的價格更便宜。伺服電機(jī)的角速度是可調(diào)的，所以它的價格昂貴。混合動力機(jī)構(gòu)系統(tǒng)中的輸出軸的恒定轉(zhuǎn)速由大功率的傳統(tǒng)電機(jī)提供；而伺服電機(jī)提供可調(diào)的速度。因此，用這種方式，不僅使得機(jī)械壓力機(jī)的曲柄軸的輸出運(yùn)動靈活可變，而且還避免使用大功率的伺服電機(jī)。因此它既可以節(jié)約機(jī)器制造代價又可以節(jié)約機(jī)器運(yùn)轉(zhuǎn)成本。圖1差速齒輪系的混合機(jī)構(gòu)工作準(zhǔn)則3、機(jī)械壓力機(jī)滑塊的速度特征機(jī)械壓力機(jī)的運(yùn)轉(zhuǎn)體現(xiàn)了周期性的變化規(guī)律。機(jī)械壓力機(jī)的滑塊在理想的工作條件下的位置和速度變化如圖2所示?；瑝K以很大的速度（稱作快速進(jìn)給階段）從頂部死角中心移到工作起點(diǎn)。當(dāng)機(jī)械壓力機(jī)的滑塊接近工作起點(diǎn)時，它的速度會從高速變成低速，然后以低速（稱作低速進(jìn)給階段）沖壓工件。低速的滑塊是為了避免對模具產(chǎn)生重大的影響，有益于塑料工件的成型。在滑塊完成沖壓工件并達(dá)到工件死角中心的底部時，滑塊會以高速返回并最終停在死角中心的頂部（稱作快速返回階段）。因此，機(jī)械壓力機(jī)的滑塊的移動速度可以分為三種情況：快速下降速度V1，緩慢工作速度V2，和快速返回速度V3。速度V1和V3應(yīng)該盡可能一樣快，速度V2應(yīng)該緩慢、靈活，目的是為了確保機(jī)械壓力機(jī)每分鐘的工作次數(shù)并能滿足不同技術(shù)的要求。事實(shí)上機(jī)械壓力機(jī)在到達(dá)死角中心的底部之前僅以一個很短的行程工作，而在其他行程中對工件來說是不工作的。4、混合機(jī)械的術(shù)語和方程4.1所有軸的角速度的關(guān)系如圖1所示在差動齒輪輪系中有三個外部軸。為了方便的表達(dá)三個軸之間的關(guān)系，和常規(guī)電機(jī)連接的軸叫軸1，和伺服電機(jī)連接的軸叫軸2，和曲軸連接的軸叫軸0。三根軸的