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1、河北工程大学毕业设计CamsandGearsAcamisaconvenientdevicefortransformingonemotionintoanother.Themachineelementhasacurvedorgroovedsurfacewhichmateswithafollowerandimpartsmotiontoit.Themotionofthecam(usuallyrotation)istransformedintofolloweroscillation,translationorboth.Becauseofthevariouscamgeometriesandthela
2、rgenumberofcanandfollowercombinations,thecamisanextremelyversatilemechanicalelement.Althoughacamandfollowermaybedesignedformotion,path,orfunctiongeneration,themajorityofapplicationsutilizethecamandfollowerforfunctiongeneration.Themostcommoncantypesaccordingtocamshapesare:diskorplatetranslating(tw
3、o-dimensionalorplanar),andcylindrical(three-dimaensionalorspatial)cams.Followercanbeclassifiedinseveralways:accordingtofollowermotion,suchastranlationoroscillation;accordingtowhetherthetranslational(straight-line)followermotionisradialoroffsetfromthecenterofthecamshaft;andaccordingtotheshapeofthe
4、followercontactsuface(e.g.,flat-face,roller,point(knife-edge),spherical,planarcurved,orspatial-curvedsurface).Inthecaseofadiskcamwitharadial(in-line)translatingrillerfollowerthesmallestcircle.thatcanbedrawntangenttothecamsufaceanconcentricwiththecamshaftisthebasecircle.Thetracerpointisapointatthe
5、centoftherollerthatgeneratesthepitchcurve.Thepressureangleistheanglebetweenthedirectionof-6-河北工程大学毕业设计thepathoftherollercenterandnormaltothepitchcurvethroughthecenteroftherollerandisthecomplementofthetransmissionangle.Neglectingfriction,thisnormalisiscollinearwiththecontactforcebetweenthecamandfo
6、llower.Asinalinkage,thepressureanglevariesduringthecycleandisameasureoftheabilityofthecamtotransfermovtiveefforttothefollower,which,inthepressenceoffriction,wouldtendtobindthefollowerintheguide.Numerousapplicationsinautomaticmachineryrequireintermittentmotion.Atypicalexamplewillcallforarise-dwell
7、-returnandperhapsanotherdwellperiodofaspecifiednumberofdegreeseach,togetherwitharequiredfollowerdisplacementmeasuredincentimetersordegrees.Thedesigner’sjobistolayoutthecamacordingly.Thefirstdecisiontobemadeistochooseth
