外文翻译--三段式圆弧凸轮分析设计 英文版.pdf

Ananalyticaldesignforthreecircular-arccamsChiaraLanni,MarcoCeccarelli*,GiorgioFiglioliniDipartimentodiMeccanica,Strutture,AmbienteeTerritorio,UniversitC18adiCassino,ViaDiBiasio43,03043Cassino(Fr),ItalyReceived10July2000；accepted22January2002AbstractInthispaperwehavepresentedananalyticaldescriptionforthreecircular-arccamproles.Anana-lyticalformulationforcamproleshasbeenproposedanddiscussedasafunctionofsizeparametersfordesignpurposes.Numericalexampleshavebeenreportedtoprovethesoundnessoftheanalyticaldesignprocedureandshowtheengineeringfeasibilityofsuitablethreecircular-arccams.C2112002ElsevierScienceLtd.Allrightsreserved.1.IntroductionAcamisamechanicalelement,whichisusedtotransmitadesiredmotiontoanotherme-chanicalelementbydirectsurfacecontact.Generally,acamisamechanism,whichiscomposedofthreedierentfundamentalpartsfromakinematicviewpoint1,2:acam,whichisadrivingelement；afollower,whichisadrivenel-ementandaxedframe.Cammechanismsareusuallyimplementedinmostmodernapplicationsandinparticularinautomaticmachinesandinstruments,internalcombustionenginesandcontrolsystems3.Camandfollowermechanismscanbeverycheap,andsimple.Theyhavefewmovingpartsandcanbebuiltwithverysmallsize.Thedesignofcamprolehasbeenbasedonsimplygeometriccurves,4,suchas:parabolic,harmonic,cycloidalandtrapezoidalcurves2,5andtheircombinations1,2,6,7.Inthispaperwehaveaddressedattentiontocamproles,whicharedesignedasacollectionofcirculararcs.Thereforetheyarecalledcircular-arccams5,8.*Correspondingauthor.E-mailaddress:ceccarelliing.unicas.it(M.Ceccarelli).0094-114X/02/$-seefrontmatterC2112002ElsevierScienceLtd.Allrightsreserved.PII:S0094-114X(02)00032-0MechanismandMachineTheory37(2002)915924/locate/mechmtCircular-arccamscanbeeasilymachinedandcanbeusedinlow-speedapplications9.Inaddition,circular-arccamscouldbeusedformicro-mechanismsandnano-mechanismssinceverysmallmanufacturingcanbeproperlyobtainedbyusingelementarygeometry.Anundesirablecharacteristicofthistypeofcamisthesuddenchangeintheaccelerationattheprolepointswherearcsofdierentradiiarejoined5.Alimitednumberofcircular-arcsisusuallyadvisablesothatthedesign,constructionandoperationofcamtransmissioncanbenotverycomplicatedandtheycanbecomeacompromiseforsimplicityandeconomiccharacteristicsthatarethebasicadvantagesofcircular-arccams8.Recentlynewattentionhasbeenaddressedtocircular-arccamsbyusingdescriptiveviewpoint10,andfordesignpurposes11,12.Inthispaperwehavedescribedthreecircular-arccamsbytakingintoconsiderationthegeo-metricaldesignparameters.Ananalyticalformulationhasbeenproposedforthreecircular-arccamsasanextensionofaformulationfortwocircular-arccamsthathasbeenpresentedinapreviouspaper12.2.Ananalyticalmodelforthreecircular-arccamsAnanalyticalformulationcanbeproposedforthreecircular-arccamsinagreementwithdesignparametersofthemodelshowninFigs.1and2.Signicantparametersforamechanicaldesignofathreecircular-arccamare:Fig.18；theriseangleas,thedwellanglear,thereturnanglead,theactionangleaaasarad,themaximumlifth1.Fig.1.Designparametersforgeneralthreecircular-arccams.916C.Lannietal./MechanismandMachineTheory37(2002)915924Thecharacteristiclociofathreecircular-arccamsareshowninFig.2as:therstcircleC1ofthecamprolewithq1radiusandcentreC1；thesecondcircleC2ofthecamprolewithq2radiusandcentreC2；thethirdcircleC3ofthecamprolewithq3radiusandcentreC3；thebasecircleC4withradiusrandthecentreisO；theliftcircleC5ofthecamprolewith(rh1)radiusandcentreO；therollercirclewithradiusqcentredonthefolloweraxis.Inadditionsignicantpointsare:DC17xD；yDwhichisthepointjoiningC1withC5；FC17xF；yFwhichisthepointjoiningC1withC3；GC17xG；yGwhichisthepointjoiningC3withC2；AC17xA；yA)whichisthepointjoiningC2withC4.xandyareCartesianco-ordinatesofpointswithrespecttothexedframeOXY,whoseoriginOisapointofthecamrotationaxis.Additionalsignicantlociare:t13whichistheco-incidenttangentialvectorbetweenC1andC3；t15whichisthecoincidenttangentialvectorbetweenC1andC5；t23whichisthecoincidenttangentialvectorbetweenC2andC3；t24whichistheco-incidenttangentialvectorbetweenC2andC4.ThemodelshowninFigs.1and2canbeusedtodeduceaformulation,whichcanbeusefulbothforcharacterizinganddesigningthreecircular-arccams.Analyticaldescriptioncanbeproposedwhenthecirclesareformulatedinthesuitableform:circleC1withradiusq21x1C0xF2y1C0yF2passingthroughpointFasx2y2C02xx1C02yy1C0x2FC0y2F2x1xF2y1yF01circleC2withradiusq22x2C0xA2y2C0yA2passingthroughpointAasx2y2C02xx2C02yy2C0x2AC0y2A2x2xA2y2yA02circleC2withradiusq22x2C0xG2y2C0yG2passingthroughpointGasx2y2C02xx2C02yy2C0x2GC0y2G2x2xG2y2yG03Fig.2.Characteristiclociforthreecircular-arccams.C.Lannietal./MechanismandMachineTheory37(2002)915924917circleC3withradiusq23x3C0xF2y3C0yF2passingthroughpointFasx2y2C02xx3C02yy3C0x2FC0y2F2x3xF2y3yF04circleC3withradiusq23x3C0xG2y3C0yG2passingthroughpointGasx2y2C02xx3C02yy3C0x2GC0y2G2x3xG2y3yG05circleC4withradiusrasx2y2r26circleC5withradius(rh1)asx2y2rh127AdditionalcharacteristicconditionscanbeexpressedintheformastherstcircleC1andliftcircleC5musthavethesametangentialvectort15atpointDexpressedasxx1yy1C0x1xDC0y1yD08thebasecircleC4andsecondcircleC2musthavethesametangentialvectort24atpointAex-pressedasxx2yy2C0x2xAC0y2yA09thesecondcircleC2andthirdcircleC3musthavethesametangentialvectort23atpointGex-pressedasxx3C0x2yy3C0y2x3xGy3yGC0x1xGC0y1yG010therstcircleC1andthesecondcircleC2musthavethesametangentialvectort12atpointFexpressedasxx1C0x3yy1C0y3x3xFy3yFC0x1xFC0y1yF011Eqs.(1)(11)maydescribeageneralmodelforthreecircular-arccamsandcanbeusedtodrawthemechanicaldesignasshowninFig.2.3.AnanalyticaldesignprocedureEqs.(1)(11)canbeusedtodeduceasuitablesystemofequations,whichallowss