基于Solidwork的同軸式三級(jí)圓柱齒輪減速器設(shè)計(jì)【三維SW】
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GEARANDSHAFTINTRODUCTIONAbstract:Theimportantpositionofthewheelgearandshaftcantfalterintraditionalmachineandmodernmachines.Thewheelgearandshaftsmainlyinstallthedirectionthatdeliversthedintattheprincipalaxisbox.Thepassingtoprocesstomakethemcanisdividedintomanymodelnumbers,usedingformanysituationsrespectively.Sowemustbethemultilayerstotheunderstandingofthewheelgearandshaftinmanyways.Keywords:Wheelgear;ShaftIntheforceanalysisofspurgears,theforcesareassumedtoactinasingleplane.Weshallstudygearsinwhichtheforceshavethreedimensions.Thereasonforthis,inthecaseofhelicalgears,isthattheteetharenotparalleltotheaxisofrotation.Andinthecaseofbevelgears,therotationalaxesarenotparalleltoeachother.Therearealsootherreasons,asweshalllearn.Helicalgearsareusedtotransmitmotionbetweenparallelshafts.Thehelixangleisthesameoneachgear,butonegearmusthavearight-handhelixandtheotheraleft-handhelix.Theshapeofthetoothisaninvolutehelicoid.Ifapieceofpapercutintheshapeofaparallelogramiswrappedaroundacylinder,theangularedgeofthepaperbecomesahelix.Ifweunwindthispaper,eachpointontheangularedgegeneratesaninvolutecurve.Thesurfaceobtainedwheneverypointontheedgegeneratesaninvoluteiscalledaninvolutehelicoid.Theinitialcontactofspur-gearteethisalineextendingallthewayacrossthefaceofthetooth.Theinitialcontactofhelicalgearteethisapoint,whichchangesintoalineastheteethcomeintomoreengagement.Inspurgearsthelineofcontactisparalleltotheaxisoftherotation;inhelicalgears,thelineisdiagonalacrossthefaceofthetoot.Itisthisgradualoftheteethandthesmoothtransferofloadfromonetoothtoanother,whichgivehelicalgearstheabilitytotransmitheavyloadsathighspeeds.Helicalgearssubjecttheshaftbearingstobothradialandthrustloads.Whenthethrustloadsbecomehighorareobjectionableforotherreasons,itmaybedesirabletousedoublehelicalgears.Adoublehelicalgear(herringbone)isequivalenttotwohelicalgearsofoppositehand,mountedsidebysideonthesameshaft.Theydevelopoppositethrustreactionsandthuscanceloutthethrustload.Whentwoormoresinglehelicalgearsaremountedonthesameshaft,thehandofthegearsshouldbeselectedsoastoproducetheminimumthrustload.Crossed-helical,orspiral,gearsarethoseinwhichtheshaftcenterlinesareneitherparallelnorintersecting.Theteethofcrossed-helicalfearshavepointcontactwitheachother,whichchangestolinecontactasthegearswearin.Forthisreasontheywillcarryoutverysmallloadsandaremainlyforinstrumentalapplications,andaredefinitelynotrecommendedforuseinthetransmissionofpower.Thereisondifferencebetweenacrossedhelicalgearandahelicalgearuntiltheyaremountedinmeshwitheachother.Theyaremanufacturedinthesameway.Apairofmeshedcrossedhelicalgearsusuallyhavethesamehand;thatis,aright-handdrivergoeswitharight-handdriven.Inthedesignofcrossed-helicalgears,theminimumslidingvelocityisobtainedwhenthehelixangleareequal.However,whenthehelixanglearenotequal,thegearwiththelargerhelixangleshouldbeusedasthedriverifbothgearshavethesamehand.Wormgearsaresimilartocrossedhelicalgears.Thepinionorwormhasasmallnumberofteeth,usuallyonetofour,andsincetheycompletelywraparoundthepitchcylindertheyarecalledthreads.Itsmatinggeariscalledawormgear,whichisnotatruehelicalgear.Awormandwormgearareusedtoprovideahighangular-velocityreductionbetweennonintersectingshaftswhichareusuallyatrightangle.Thewormgearisnotahelicalgearbecauseitsfaceismadeconcavetofitthecurvatureoftheworminordertoprovidelinecontactinsteadofpointcontact.However,adisadvantageofwormgearingisthehighslidingvelocitiesacrosstheteeth,thesameaswithcrossedhelicalgears.Wormgearingareeithersingleordoubleenveloping.Asingle-envelopinggearingisoneinwhichthegearwrapsaroundorpartiallyenclosestheworm.Agearinginwhicheachelementpartiallyenclosestheotheris,ofcourse,adouble-envelopingwormgearing.Theimportantdifferencebetweenthetwoisthatareacontactexistsbetweentheteethofdouble-envelopinggearswhileonlylinecontactbetweenthoseofsingle-envelopinggears.Thewormandwormgearofasethavethesamehandofhelixasforcrossedhelicalgears,butthehelixanglesareusuallyquitedifferent.Thehelixangleonthewormisgenerallyquitelarge,andthatonthegearverysmall.Becauseofthis,itisusualtospecifytheleadangleontheworm,whichisthecomplementofthewormhelixangle,andthehelixangleonthegear;thetwoanglesareequalfora90-deg.Shaftangle.Whengearsaretobeusedtotransmitmotionbetweenintersectingshaft,someofbevelgearisrequired.Althoughbevelgearareusuallymadeforashaftangleof90deg.Theymaybeproducedforalmostanyshaftangle.Theteethmaybecast,milled,orgenerated.Onlythegeneratedteethmaybeclassedasaccurate.Inatypicalbevelgearmounting,oneofthegearisoftenmountedoutboardofthebearing.Thismeansthatshaftdeflectioncanbemorepronouncedandhaveagreatereffectonthecontactofteeth.Anotherdifficulty,whichoccursinpredictingthestressinbevel-gearteeth,isthefacttheteetharetapered.Straightbevelgearsareeasytodesignandsimpletomanufactureandgiveverygoodresultsinserviceiftheyaremountedaccuratelyandpositively.Asinthecaseofsqurgears,however,theybecomenoisyathighervaluesofthepitch-linevelocity.Inthesecasesitisoftengooddesignpracticetogotothespiralbevelgear,whichisthebevelcounterpartofthehelicalgear.Asinthecaseofhelicalgears,spiralbevelgearsgiveamuchsmoothertoothactionthanstraightbevelgears,andhenceareusefulwherehighspeedareencountered.Itisfrequentlydesirable,asinthecaseofautomotivedifferentialapplications,tohavegearingsimilartobevelgearsbutwiththeshaftoffset.Suchgearsarecalledhypoidgearsbecausetheirpitchsurfacesarehyperboloidsofrevolution.Thetoothactionbetweensuchgearsisacombinationofrollingandslidingalongastraightlineandhasmuchincommonwiththatofwormgears.Ashaftisarotatingorstationarymember,usuallyofcircularcrosssection,havingmounteduponitsuchelementsasgears,pulleys,flywheels,cranks,sprockets,andotherpower-transmissionelements.Shaftmaybesubjectedtobending,tension,compression,ortorsionalloads,actingsinglyorincombinationwithoneanother.Whentheyarecombined,onemayexpecttofindbothstaticandfatiguestrengthtobeimportantdesignconsiderations,sinceasingleshaftmaybesubjectedtostaticstresses,completelyreversed,andrepeatedstresses,allactingatthesametime.Theword“shaft”coversnumerousvariations,suchasaxlesandspindles.Anaxleisashaft,witherstationaryorrotating,norsubjectedtotorsionload.Ashirtrotatingshaftisoftencalledaspindle.Wheneitherthelateralorthetorsionaldeflectionofashaftmustbeheldtocloselimits,theshaftmustbesizedonthebasisofdeflectionbeforeanalyzingthestresses.Thereasonforthisisthat,iftheshaftismadestiffenoughsothatthedeflectionisnottoolarge,itisprobablethattheresultingstresseswillbesafe.Butbynomeansshouldthedesignerassumethattheyaresafe;itisalmostalwaysnecessarytocalculatethemsothatheknowstheyarewithinacceptablelimits.Wheneverpossible,thepower-transmissionelements,suchasgearsorpullets,shouldbelocatedclosetothesupportingbearings,Thisreducesthebendingmoment,andhencethedeflectionandbendingstress.AlthoughthevonMises-Hencky-Goodmanmethodisdifficulttouseindesignofshaft,itprobablycomesclosesttopredictingactualfailure.Thusitisagoodwayofcheckingashaftthathasalreadybeendesignedorofdiscoveringwhyaparticularshafthasfailedinservice.Furthermore,thereareaconsiderablenumberofshaft-designproblemsinwhichthedimensionareprettywelllimitedbyotherconsiderations,suchasrigidity,anditisonlynecessaryforthedesignertodiscoversomethingaboutthefilletsizes,heat-treatment,andsurfacefinishandwhetherornotshotpeeningisnecessaryinordertoachievetherequiredlifeandreliability.Becauseofthesimilarityoftheirfunctions,clutchesandbrakesaretreatedtogether.Inasimplifieddynamicrepresentationofafrictionclutch,orbrake,twoinertiasI1andI2travelingattherespectiveangularvelocitiesW1andW2,oneofwhichmaybezerointhecaseofbrake,aretobebroughttothesamespeedbyengagingtheclutchorbrake.Slippageoccursbecausethetwoelementsarerunningatdifferentspeedsandenergyisdissipatedduringactuation,resultinginatemperaturerise.Inanalyzingtheperformanceofthesedevicesweshallbeinterestedintheactuatingforce,thetorquetransmitted,theenergylossandthetemperaturerise.Thetorquetransmittedisrelatedtotheactuatingforce,thecoefficientoffriction,andthegeometryoftheclutchorbrake.Thisisprobleminstatic,whichwillhavetobestudiedseparatelyforeathgeometricconfiguration.However,temperatureriseisrelatedtoenergylossandcanbestudiedwithoutregardtothetypeofbrakeorclutchbecausethegeometryofinterestistheheat-dissipatingsurfaces.Thevarioustypesofclutchesandbrakesmaybeclassifiedasfllows:1.Rimtypewithinternallyexpandingshoes2.Rimtypewithexternallycontractingshoes3.Bandtype4.Diskoraxialtype5.Conetype6.MiscellaneoustypeTheanalysisofalltypeoffrictionclutchesandbrakesusethesamegeneralprocedure.Thefollowingsteparenecessary:1.Assumeordeterminethedistributionofpressureonthefrictionalsurfaces.2.Findarelationbetweenthemaximumpressureandthepressureatanypoint3.Applytheconditionofstaticalequilibriumtofind(a)theactuatingforce,(b)thetorque,and(c)thesupportreactions.Miscellaneousclutchesincludeseveraltypes,suchasthepositive-contactclutches,overload-releaseclutches,overrunningclutches,magneticfluidclutches,andothers.Apositive-contactclutchconsistsofashiftleverandtwojaws.Thegreatestdifferencesbetweenthevarioustypesofpositiveclutchesareconcernedwiththedesignofthejaws.Toprovidealongerperiodoftimeforshiftactionduringengagement,thejawsmayberatchet-shaped,orgear-tooth-shaped.Sometimesagreatmanyteethorjawsareused,andtheymaybecuteithercircumferentially,sothattheyengagebycylindricalmating,oronthefacesofthematingelements.Althoughpositiveclutchesarenotusedtotheextentofthefrictional-contacttype,theydohaveimportantapplicationswheresynchronousoperationisrequired.Devicessuchaslineardrivesormotor-operatedscrewdriversmustruntodefinitelimitandthencometoastop.Anoverload-releasetypeofclutchisrequiredfortheseapplications.Theseclutchesareusuallyspring-loadedsoastoreleaseatapredeterminedtoque.Theclickingsoundwhichisheardwhentheoverloadpointisreachedisconsideredtobeadesirablesignal.Anoverrunningclutchorcouplingpermitsthedrivenmemberofamachineto“freewheel”or“overrun”becausethedriverisstoppedorbecauseanothersourceofpowerincreasethespeedofthedriven.Thistypeofclutchusuallyusesrollersorballsmountedbetweenanoutersleeveandaninnermemberhavingflatsmachinedaroundtheperiphery.Drivingactionisobtainedbywedgingtherollersbetweenthesleeveandtheflats.Theclutchisthereforeequivalenttoapawlandratchetwithaninfinitenumberofteeth.Magneticfluidclutchorbrakeisarelativelynewdevelopmentwhichhastwoparallelmagneticplates.Betweentheseplatesisalubricatedmagneticpowdermixture.Anelectromagneticcoilisinsertedsomewhereinthemagneticcircuit.Byvaryingtheexcitationtothiscoil,theshearingstrengthofthemagneticfluidmixturemaybeaccuratelycontrolled.Thusanyconditionfromafullsliptoafrozenlockupmaybeobtained.IntroducitonofMachiningHaveashapeasaprocessingmethod,allmachiningprocessfortheproductionofthemostcommonlyusedandmostimportantmethod.Machiningprocessisaprocessgeneratedshape,inthisprocess,Driversdeviceontheworkpiecematerialtobeintheformofchipremoval.Althoughinsomeoccasions,theworkpieceundernocircumstances,theuseofmobileequipmenttotheprocessing,However,themajorityofthemachiningisnotonlysupportingtheworkpiecealsosupportingtoolsandequipmenttocomplete.Machiningknowtheprocesshastwoaspects.Smallgroupoflow-costproduction.Forcasting,forgingandmachiningpressure,everyproductionofaspecificshapeoftheworkpiece,evenaspareparts,almosthavetospendthehighcostofprocessing.Weldingtorelyontheshapeofthestructure,toalargeextent,dependoneffectiveintheformofrawmaterials.Ingeneral,throughtheuseofexpensiveequipmentandwithoutspecialprocessingconditions,canbealmostanytypeofrawmaterials,mechanicalprocessingtoconverttherawmaterialsprocessedintothearbitraryshapeofthestructure,aslongastheexternaldimensionslargeenough,itispossible.Becauseofaproductionofspareparts,evenwhenthepartsandstructureoftheproductionbatchsizesaresuitablefortheoriginalcasting,Forgingorpressureprocessingtoproduce,butusuallyprefermachining.Strictprecisionandgoodsurfacefinish,Machiningthesecondpurposeistheestablishmentofthehighprecisionandsurfacefinishpossibleonthebasisof.Manyparts,ifanyothermeansofproductionbelongingtothelarge-scaleproduction,WellMachiningisalow-toleranceandcanmeettherequirementsofsmallbatchproduction.Besides,manypartsontheproductionandprocessingofcoarseprocesstoimproveitsgeneralshapeofthesurface.Itisonlynecessaryprecisionandchooseonlythesurfacemachining.Forinstance,thread,inadditiontomechanicalprocessing,almostnootherprocessingmethodforprocessing.Anotherexampleistheblacksmithpieceskeyholeprocessing,aswellastrainingtobeconductedimmediatelyafterthemechanicalcompletionoftheprocessing.PrimaryCuttingParametersCuttingtheworkpieceandtoolbasedonthebasicrelationshipbetweenthefollowingfourelementstofullydescribe:thetoolgeometry,cuttingspeed,feedrate,depthandpenetrationofacuttingtool.CuttingToolsmustbeofasuitablematerialtomanufacture,itmustbestrong,tough,hardandwear-resistant.Toolgeometry-tothetipplaneandcutteranglecharacteristics-foreachcuttingprocessmustbecorrect.Cuttingspeedisthecuttingedgeofworkpiecesurfacerate,itisinchesperminutetoshow.Inordertoeffectivelyprocessing,andcuttingspeedmustadapttothelevelofspecificparts-withknives.Generally,themorehardworkpiecematerial,thelowertherate.ProgressiveTooltospeediscutintotheworkpiecespeed.Iftheworkpieceortoolforrotatingmovement,feedrateperroundoverthenumberofinchestothemeasurement.Whentheworkpieceortoolforreciprocatingmovementandfeedrateoneachtripthroughthemeasurementofinches.Generally,inotherconditions,feedrateandcuttingspeedisinverselyproportionalto。Depthofpenetrationofacuttingtool-toinchesdollars-isthetooltotheworkpiecedistance.Rotarycuttingittothechiporequaltothewidthofthelinearcuttingchipthickness.Roughthanfinishing,deeperpenetrationofacuttingtooldepth.WearsofCuttingToolWealreadyhavebeenprocessedandtherattleofthecountlesscracksedgetool,welearnthattoolweararebasicallythreeforms:flankwear,theformerflankwearandV-Notchwear.Flankwearoccurredinboththemainbladeoccurredviceblade.Onthemainblade,shoulderremovedbecausemostmetalchipmandate,whichresultedinanincreasecuttingforceandcuttingtemperatureincrease,Ifnotallowedtocheck,Thatcouldleadtotheworkpieceandthetoolvibrationandprovideforefficientcuttingconditionsmaynolongerexist.Vice-bladedon,itisdeterminedworkpiecedimensionsandsurfacefinish.Flankwearsizeofthepossiblefailureoftheproductandsurfacefinisharealsoinferior.Inmostactualcuttingconditions,astheprincipalintheformerfirstdeputyflankbeforeflankwear,weararrivalenough,Toolwillbeeffective,theresultsaremadeunqualifiedparts.AsToolstressonthesurfaceuneven,chipandflankbeforeslidingcontactzonebetweenstress,inslidingcontactthestartofthelargest,andincontactwiththetailofzero,soabrasivewearintheregionoccurred.Thisisbecausethecardcuttingedgethanthenearbysettlementsnearthemoreseriouswear,andbladedchipduetothevicinityoftheformerflankandlostcontactwearlighter.Thisresultsthetool,workpieceandchip.Atypicalsetofisothermsisshowninfigurewhereitcanbeseenthat,ascouldbeexpected,thereisaverylargetemperaturegradientthroughoutthewidthofthechipastheworkpiecematerialisshearedinprimarydeformationandthereisafurtherlargetemperatureinthechipadjacenttothefaceasthechipisshearedinsecondarydeformation.Thisleadstoamaximumcuttingtemperatureashortdistanceupthefacefromthecuttingedgeandasmalldistanceintothechip.Sincevirtuallyalltheworkdoneinmetalcuttingisconvertedintoheat,itcouldbeexpectedthatfactorswhichincreasethepowerconsumedperunitvolumeofmetalremovedwillincreasethecuttingtemperature.Thusanincreaseintherakeangle,allotherparametersremainingconstant,willreducethepowerperunitvolumeofmetalremovedandcuttingtemperatureswillreduce.Whenconsideringincreaseinundeformedchipthicknessandcuttingspeedthesituationismorecomples.Anincreaseinundeformedchipthicknessandcuttingspeedthesituationismorecomplex.Anincreaseinundeformedchipthicknesstendstobeascaleeffectwheretheamountsofheatwhichpasstotheworkpiece,thetoolandchipremaininfixedproportionsandthechangesincuttingtemperaturetendtobesmall.Increaseincuttingspeed,however,reducetheamountofheatwhichpassesintotheworkpieceandthisincreasethetemperatureriseofthechipinprimarydeformation.Further,thesecondarydeformationzonetendstobesmallerandthishastheeffectofincreasingthetemperaturesinthiszone.Otherchangesincuttingparametershavevirtuallynoeffectonthepowerconsumedperunitvolumeofmetalremovedandconsequentlyhavevirtuallynoeffectonthepowerconsumedperunitvolumeofmetalremovedandconsequentlyhavevirtuallynoeffectonthecuttingtemperatures.Sinceithasbeenshownthatevensmallchangesincuttingtemperaturehaveasignificanteffectontoolwearrate,itisappropriatetoindicatehowcuttingtemperaturescanbeassessedfromcuttingdata.Themostdirectandaccuratemethodformeasuringtemperaturesinhigh-speed-steelcuttingtoolsisthatofWright&Trentwhichalsoyieldsdetailedinformationontemperaturedistributionsinhigh-speed-steeltoolswhichrelatesmicrostructuralchanges
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