机械外文翻译-凸轮.doc

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1、附录一：外文资料原文ELEMENTSOFCAMDESIGNHowtoplanandproducesimplebutefficientcamsforpetrolenginesandothermechanismsCamsareamongthemostversatilemechanismsavailable．Acamisasimpletwo-memberdevice．Theinputmemberisthecamitself，whiletheoutputmemberiscalledthefollower．Throughtheuseofcams，a

2、simpleinputmotioncanbemodifiedintoalmostanyconceivableoutputmotionthatisdesired．Someofthecommonapplicationsofcamsare——Camshaftanddistributorshaftofautomotiveengine——Productionmachinetools——Automaticrecordplayers——Printingmachines——Automaticwashingmachines——Automaticdishwa

3、shersThecontourofhigh-speedcams(camspeedinexcessof1000rpm)mustbedeterminedmathematically．However，thevastmajorityofcamsoperateatlowspeeds(lessthan500rpm)ormedium-speedcamscanbedeterminedgraphicallyusingalarge-scalelayout．Ingeneral，thegreaterthecamspeedandoutputload，thegrea

4、termustbetheprecisionwithwhichthecamcontourismachined．Camsinsomeformorotherareessentialtotheoperationofmanykindsofmechanicaldevices.Theirbest-knownapplicationisinthevalve-operatinggearofinternalcombustionengines,buttheyplayanequallyimportantpartinindustrialmachinery,fromp

5、rintingpressestoreapingmachines.Ingeneral,acamcanbedefinedasaprojectiononthefaceofadiscorthesurfaceofacylinderforthepurposeofproducingintermittentreciprocatingmotionofacontactingmemberorfollower.Mostcamsoperatebyrotarymotion,butthisisnotanessentialconditionandinspecialcas

6、esthemotionmaybesemi-rotary，oscillatoryorswinging.Evenstraight-linemotionoftheoperatingmemberispossible,thoughthetermcammaynotbeconsideredproperlyapplicableinsuchcircumstances.Mosttextbooksonmechanicsgivesomeinformationonthedesignofcamsandshowexamplesofcamformsplottedtopr

7、oducevariousordersofmotion.Whereneithertheoperatingspeednorthemechanicaldutyisveryhigh,thereisagooddealoflatitudeinthenermissibledesignofthecamanditisonlynecessarytoavoidexcessivelysteepcontoursorabruptchangeswhichwouldresultinnoise,impactshock,andsidepressureonthefollowe

8、r.But,withincreaseofeitherspeedorload,muchmoreexactingdemandsaremadeonthecam,callingforthemostca