双层柔性铰链微小夹持器英文版

1、TheDesignofTwoJayerFlexibleHingeMilli-gripperHuibaoChenPingSunDeptofPrecisionMech.Eng.ShanghaiUniveisityJiading.shanghai201800,P.R.CAbstractThepaperintroducesthedesign,manufactureandexperimentofthetwo-layerflexiblelungemilli-gripperindetails.Afterthestmetureandthecharactersofpiezoelectricelementandt

2、wo-layerflexiblehingeareanalyzed,theamplificationofdisplacementiscalculated.Thegripperhashighsensitivity,simplestructure,awiderangofusageandagreatfuturesuchasmilli-robotformedicaltreatment,inspectingandminitubeaswellasmilitaryusage.Itisanewtypeofmillimachine.1.INTRODUCTIONEversincemicio-clectyonicte

3、clinologyfounditsvzayinvanousfieldsofmechanicalenguiecnng.Mechafaonichasbecometliemostnnpoitantfeatureofmodemmechanicalscienceandteclinology.This,atthesametime,greatlystnnulatedtlieprecisionmachinetodeveloptowardsmicioandnitelligent.Iinitiatedberweenmidandlate80s,tliestudyofmicromachnieintensivelyha

4、sreflected.MicromachinecanbedividedintomicromachineandmillimachineMillnnachinevzhichhasthecharacterofmillimetersizeandmicromachinevzhichhasthecharacterofmicronsizehavebecomethefocusofup-to-dateresearchinmteinationalscienceandtechnologysocietyThesatusinmedicaltreatment,mecroelectronicprecisionmantfac

5、ture,microassemblyandacmauticcannotbereplacedbyotliersizelimitedmachines,henceitreasonablyfastisdeveloped.Milli-gnppeiisaveiynnpoitantpartbothintliedevelopmentofmicro-robotandinthepracticeofmillimachine.Therefore,weisnovzheadingforthestudyandthedevelopmentofmollogripper.Themilli-gnppeiismadeupoftwop

6、artsdnvingpartandoperatingpartTherearetwolindsofcommondrivingparts.OneiscalledPZT(piezoelectric)actuator,vzhichhasthecharactersofsunplepinciple,steadyactionandhighresponseInpresent,tlierearemanytypesofOperatingmechanism,butmainlytlierearethreefomisinourresearchandusegearandrackmechanism,obliquevzedg

7、emechanismandflexiblehingemechansmTheflexiblehingemechanismwhichcanamplifythemiciodisplacementintnnesisbettertliantheothertwoUtilizingtinsadvantage,itismadeupthemilli-gtippeiusingPZTactuatorwithPZTelementtogetlierFiguregivesamodelwemadeFigurelaisasinglestageflexiblehingegripperandfigurelbistwo-stage

8、flexiblehingegripper.卜singleKtruclureb(uo-jetanictuneFig1:Flexiblelungemilli-grippersHowever,thedefonnationofthePZTclementisquitelimited(about6.5/mi/lOOvAlthoughwehavesucceededinamplify!ngtomechanism:theoutputofgreppersisstillnotlarge.(normallyabout90/mi/10(X)ftheamplificationofmechanismisincreased,

9、thegripper*ssizewillbebiggeranditstsingfieldwillbelimited.Inorsertoincreasetheamplificationandnottoenlargethegripperssize.anothertypeogmilli-gripperisdesignedtistheweo-layerflexiblehingemilligripperusingPZTactuator.2.STRUCTUREANDACTIONPRINCIPLEThetvzo-layerflexilehingemilligiipperisanintegratedmodul

10、ewhichtuenselectricpowerintomechanicpowertorealizethegnppingfunction.ItsdrivingsourceistliePZTelementwhichisembeddedintliecenteiofthefirstlayerflexiblehinge,WlientherelevantvoltageappliedtotliePZTelement,thePZTelementproductsdefonnation,tlierebymakingthefirstlayerflexiblehingerealizethefirststageamp

11、lificationofdisplacementandthen,itwillmakethesecondlayeirealizethesecondstageamplification,atthesametime,realizethegnppingfunction,figure2sitliesimplegraphoftliegnppeiFig.2:Two-layerflexiblehingemilli-gnpperTheactuatoristhestackedPZTelement,whichismadeupofmanylayersofPZTelementlamellae(figure3showst

12、his)Theieareelectiodesalongtliepolarizationdirectionofthebothsodesoftheelement,thepolarizationdirectionofadjacentlamellaeisoppositedirectionsofelechicfield.sotheyhacetliesamedirectionsofdisplacement.WhenmanyPZTelementlamellaeareconnectedeceiyoneisunderthesamevoltage,andtliewholedisplaecmentisthesumo

13、fallthelamellaesdiplacement.Fig.3ThestmcturegraphofstackedPZTelementThehingeofflexiblehingemechanismisatypeofelasticdeformationatoundaxis,v/hichisreceisibleTherearetwokindsofhinges,tliesingleaxisandthedoubleaxis,andv/echoosetliesingleaxisone.(figure4)Fig.4:Hingedunensionsandvariousforcesandmomentswh

14、ichcausedeflectionsIndesignnig,theinputandoutputaxismustbennnble,andhingesshouldhaverigidityenough.Inpractice,tliegnppingendsofthegrippershouldhavegreateroutput,soweusethetvzosingle-stageflexiblehingemechanisms,aseachonecanamplifyonestage,Thetwomechanismsareconnectedtogetherwithhinge,inthisway,tliey

15、formtheoperatingpartofthetwoJayerflexiblehingemilli-giippeiThisdesigncannotonlydecreasetliestructuresizeofgripperinXandYdirectionsbutcanalsoincreasetlieamplificationofthedisplacement.Inworkingcondition,tlierearerelativerotationattheconnectionofthelointtodsSo,tlieconnectionstyleshouldkeeptherelativep

16、ositionbetvzeentlietwojointeods,andbeabletorotatefreelyatthesametime.Anditalsoshouldpreventtheclearancefitbetweentlieshaftandtheholefbomlosingtoomuchdisplacement,soweusetherotationfitwithsmallclearanceec.o.5H8/f7.3CALCULATINGANDANALYZINGOFTHEGRIPPERSSTRUCTURETheoperatingmechanismoftwo-layerflexibleh

17、ingemille-gripperismadeupoftwoparts,andalsomadeupoftvzoparts,figure5showstlieloadnigconditionofthetvzosingle-stageflexiblehingemechanismFig5TheloadingconditionofflexiblehingesFigure5aisthefirstlayersingle-gradeflexiblehingemechanism,andstmctureissymmetric.Tomakebriefmerelyonesideoftheoutputiscalcula

18、tedThesimpleloadinggraphisshownasfigure6.Accordingtothetheoryoftheequilibriumofstaticforceandmomentthefollowingequationsiscalculated:lbFig6:Thesimpledrawingofstructure口AL.A.nAz-AX-AXrFx一FlhFx=Mkci=Ax2.kc3,0=-=-1心+心IfA=杀+雄円=心+心ThentherewillbezlAF-L8=51+ABecausey=lb&Then1?+Ak&12+Ak,Furthermore,ifagive

19、nobjectisgripped,thefollowingrelationswillexist.Ay=BAz-C(4)Where1+A-Kq13+Ak,WhenBisaconstant,expresstheamplificationoftheaboveflexiblelunge,CisfunctionofFy,butifgripsagivenobject,FywillbeaconstantandCwillbeaconstanttoo.AzissubjecttothestnictureofthestackedPZTelement.AforceFzonlychargesonthestackedPZ

20、TelementinZ&rectionwhenworking,thesimplegraphofforceisshownasfigure7.Fig7TheloadingconditionofthesrackedPZTelementThethicknessofalamellaofthePZTelementist,andthedisplacementoftheelementlamellaisAt.AtcanbecalculatedwithfollowingequationAt=(fEt+Ezt(5)岛,d33aretliepeifonnanceparameteroftliePZTelementela

21、sticconstant,2.52x1011d33piczoclectiicconstant,9.95xl0-1IfthesectionareaoftheelementisS,thechargingvoltageisV,tlienThetotaldisplacementifnlayersofPZTelementisAzAz=nAt=為Fzn七+d33Vn(6)sAsthedisplacementofthePZTelementisdifferentfromeachother,theelasticcounterforcefromthelungeisdifferenteither,Aziscalcu

22、latedbyfollowingequations,andthesimplegraphoflondingconditionisshownasfigure6.(replacingFzbyFA)Az=2A+d33.v.n,ForthisreasonAz=d33V-n此i】tk&(1?+AkS哇Fy%ntl(12+Aks+城k&nt1IfD=.li為i】tk&(1，+AkSThentherewillbe此片入ntl(P+Ak&)s+務监ntAz=DVn-P(9)Fromtheaboveformula(9)weknowtliatthePZTelementthatdrivestheflexiblehin

23、gemechainsmcannotworkunderthemaximumdeformationbecauseofthecounterforces.SubstituteAzintoequation(4).Thefollowingequationcanbegot:y=Md33Vn-N(10)IntheaboveequationM=ED=1+Ak&1爲mtk。Q?+AksN=PB+C二1%|A.%.F+Akl2+4k&涯Fyjblltl(1，+Ak&)s+醴k&iitWhenworking,theoutputAyisalinearfunctionoftheexertedvoltage.Through

24、thevoltagechargedonthePZTelement,theoutputofthegripperiscontrolledandadjusted.Mistheamplificationofthemechainsmwithoutcharge/Theamplificationofthefirstlayeroftheflexiblehingecanbegot:(Fy=0,D=1)11b仁(ID1+Ak&Theloadingconditionofthesecondlayerofflexiblehingeisshownasfigure5b.Itisaamplifyingmechainsmtha

25、tmakesuseofthechangeofarmslength,solargeramplificatuioncanbegot,andtheamplificationcanbecalculatedasbelow:K3=-(12)Inourdesign,thestrucluresizeoftheflexiblehingeisdecidedonthebasisoftensilerigidity.shearingrigidityandtorsionalrigidityenough,theparametertobedesignedispresentedinthetablebelowTable1Hing

26、eN210RadiusR(mm)0.300.30Hingewidtht(mm)0300.30Linkwidthh(mm)1701.30Hingethicknessb(mm)2002.00Distancebetweenhinges1(mm)2352.35=14911%mY-P=-2tail1/=+Jl-(l+0-汙J20+0Y-PypJl-(l+0fInwhichF=0,andtheparameterofthematerialaretenslerigidity:Inwhichth0=2R2REelasticmodulusY-PInwhich0=-2tan17i-(i+z?-z)2Gshearin

27、gelasticmodulusTorsionalrigidity:k厂牛“6484%z1+03+20+0，7(20+内6(1+0)_(20+俨於_tan10Jl(1+0一汀Thentheamplificationofthetwo-layerflexiblehingenulli-gripperis:12+小I3=35.11Figure8showsthesizeofthestructureformainparts.Figure9showsthemodeloftwo-layerflexiblehingenulli-gripperwemade.Fig.8Thestructuresizeofmainpa

28、rtsFig9Two-layerflexiblehingemilli-grippermodelWhentheinputofdrivingelementisAz.theoutputofthegripper(Fy=0)iscalculatedasfollowingrelation2Ay=k-Az-2(13)Inwhichthemostfitclearance,0030mmWhen0.5So,theoutputofthegripperis2Ay=35.11Az-0.060(14)1.EXPERIMENTANDANALYZINGMaterialThegripperconsistoftwomechani

29、sms,butthestnictureformsareallflexiblelungeObviously,theflexiblehingetakeadvantageofthecharactersofoneselfelastic.So,whenselectingmaterial,theelasticfunction,thesensitivenessaswellashighdiamagneticshouldbeprefered.SuchasQBc2,QS116.50.1asthematerialofflexiblehingeAssemblingWegetthestackedPZTelementfr

30、omTOKINcompany.Ithasthecharactersofsmallsize,highresponseandlowdrivingvoltage.TheparameterofNLA-2x3x9stackedPZTelementusedduringtheexperimentarelistedasthefollowingfrom:Table2Sizeaxbxc(mm)2x3x9MaximumvoltageV100Maximumloadkg/lOOV2120%Deformation/Z1I1/10(V6.510%Stacks65Distancebetweenpoles/fill115Ins

31、ulationresistanceMG500Capacitance11F197Themanufactureoftheflexiblehingeusetheelectricmachiningtechnology.Themachiningaccueacyofthetechnologycanbe/Zillgrade.Theneedofdesigncanbesatisfiedbasically.Assemblysequenceare:Twoflexiblelungemechanismsaredrilledholetogether一connectingtwpmechanisms一assemblingth

32、edrivingelement.Inwhich.assemblingPZTelementisextremelydifficult.AsaresultoftheoutputofPZTelementisverysmall/Allandtheoutputof(ZTelementcanbereducedinassemblingprocess.TheassemblingaccuracymustbehighForthisreason,wedesognedfollowingstructure:SizeofmountingPZTelementlengthsize1=ofPZTelementThroughgri

33、ndingthesize1ofthemechanism,wecanachieveamicrointerferencetolz,thatsthefitbetweengrippingmechanismandPZTelementissmallinterferencefit.4.1MeasuringADWY-2typevibratingdisplacementinstrumentwasusedtodetectedthedisplacementoftheZTelement.Measuringrangeis0.05100/ZillThemeasuingvalueofthePZTelement:whenlO

34、OvisappliedtheoutputofPZTelementis6.4“11Hencethen，&omformula(14),themostoutputofthegrippercanbecalculated:T=2Ay=35.11x0.0064-0.060=0.1647nniThemeasurementofactualoutputgoontheexperimentalfacilityinfigure10.andtheoutputofthegripperwedetectedisintable3.MeasuringnumberN1o345Outputofdisplacement2Ay0.121

35、0.1190.1350.1240.130MeasuringnumberN678910Outputofdisplacement2Ay0.1180.1310.1220.1260.131Theactualoutputofthegrippercanbegotyieal=2Ay=0.125nmOverallsizeoftwo-layerflexiblelungenulli-gnpperis15.2x9.8x3.Totalweightis3gAftertheexperimentresultbecomparedtotheorycalculatingvalue,wecangot:yrealytfeoiy,and&sparityis23.6%5.CONCLUSIONTwo-layerflexiblehingenulli-gripperisanewintegratednulli-gripper