主講人：趙慧、楊國星TianjinLightIndustryVocationalTechnicalCollege

DrawingaGearPartIIntroductiontotheClassPARTIIntroductiontotheClassGearsarewidelyusedtransmissioncomponentsinmachinery;bymeansofgeardrives,onecantransmitmotionandtorque,andalterboththespeedanddirectionofmotion.PartIIBasicKnowledgeofGearsPARTIIOverviewTheteethofagearareraisedpartsonthegearthatfitintothecorrespondingspacesbetweenthematchinggear'steeth.Theirshapeensuresthatonegeardrivesthemotionofanothergear.Theteethofapairofgearsalternatelyengagewitheachother,allowingforaspecific,regularrelativemotionandshape,whichisknownasmeshing.ClassificationofGearsUsedfortransmissionbetweentwoparallelshaftsUsedfortransmissionbetweentwointersectingshaftsUsedfortransmissionbetweentwonon-parallelshaftsCylindricalGearBevelGearWormandWormGearClassificationofGears

Cylindricalgearsaregenerallyclassifiedbasedonthedirectionoftheirteeth,whichincludestraightteeth,helicalteeth,andherringboneteeth.HerringboneTooth

CylindricalGearHelicalTooth

CylindricalGearStraightToothCylindricalGearStraightToothCylindricalGearStructureoftheGearTeethoftheGearHubSpokesWheelRimKeywayShaftHoleStraightToothCylindricalGearBasicTerminologyandSymbolsofStraightToothCylindricalGearsTipCircle(Diameterda)ThecirclethatpassesthroughthetopofeachtoothofthegeariscalledtheTipcircle.Itsdiameterisrepresentedbyda.RootCircle(Diameterdf)Thecirclethatpassesthroughtherootofeachtoothofthegeariscalledtherootcircle.Itsdiameterisrepresentedbydf.PitchCircle(Diameterd)Whenmachiningthegear,thecircleusedtodefinethegeartoothpitchiscalledthepitchcircle.Itsdiameterisrepresentedbyd.Atthepitchcircle,thewidthofthetoothslotisequaltothetooththickness.StraightToothCylindricalGearBasicTerminologyandSymbolsofStraightToothCylindricalGearsAddendumHeight（ha）Theradialdistancebetweenthepitchcircleandtheaddendumcircleiscalledtheaddendumheight,representedbyha.DedendumHeight（hf）Theradialdistancebetweenthepitchcircleandtherootcircleiscalledthededendumheight,representedbyHf.TotalToothHeight（h）Theradialdistancebetweentheaddendumcircleandtherootcircleiscalledthetotaltoothheight,representedbyh.Itiscalculatedas:h=ha+hfStraightToothCylindricalGearBasicTerminologyandSymbolsofStraightToothCylindricalGearsPitch(p)Thearclengthbetweentwocorrespondingpointsonadjacentteethalongthepitchcircleiscalledthepitch.Itisrepresentedbyp.Thepitchiscalculatedas:p=

Tooth

Thickness(s)+Tooth

Width(e)Modulus(m)Themodulusisoneoftheimportantparametersofgears.Ifthenumberofteethonthegearisdenotedasz,thenthemodulusisdefinedas:z，thenthemodulusisdefinedas:

d=mzWheredisthepitchcirclediameter.StraightToothCylindricalGearModulusStandardModulusforCylindricalGears（GB/T1357-2008

）FirstSeries1，1.25，1.5，2，2.5，3，4，5，6，8，10，12，16，20，25，32，40，50SecondSeries1.125，1.375，1.75，2.25，2.75，3.5，4.5，5.5，(6.5)，7，9，11，14，18，22，28，35，45StraightToothCylindricalGearCalculationofVariousGearPartDimensionsPartIIIDrawingMethodsforStraight-ToothCylindricalGearsPARTIIISpecifiedDrawingMethodforaSingleGearGearBody:

Drawthebodyportionintrueprojection.GearTeeth:

Calculatethefollowingdiameters:d、da、df,Thendrawthetoothportionasfollows:Tipcircleandtipline:usethicksolidlines.Pitchcircleandpitchline:usechainlines(dash-dotlines).Rootcircleandrootline:usethinsolidlines;thesemaybeomittedifclaritypermits.PitchLineTipLineRootLineTipCirclePitchCircleUseasectionalviewforthefrontviewWhenthecuttingplanepassesthroughthegear’saxis,thegearteetharedrawnwithoutsectioning.Drawthetipcircleandtiplinewiththicksolidlines.Drawthepitchcircleandpitchlinewithchainlines(dash-dot).Drawtherootlinewiththicksolidlines;therootcirclemaybeomitted.

SpecifiedDrawingMethodforaSingleGearInthemeshingarea:

Intheviewperpendiculartothecylindricalgearaxis(representingacircleview),thetipcirclesofthetwomeshinggearsaredrawnwiththicksolidlines,withthetwocirclestangenttoeachother.Thetipcirclesinthemeshingareacanalsobeomitted,aslongasthetwocirclesremaintangent.Intheviewparalleltothecylindricalgearaxis:

Ifnotsectioned,thetiplineisomitted,andthepitchlineisdrawnwithathicksolidline.Inthenon-meshingarea:Drawthegearasasinglegear,followingtheprescribeddrawingmethodforindividualgears.RegulatedDrawingMethodforGearMeshingWhenthecuttingplanepassesthroughtheaxesoftwomeshinggears,inthemeshingarea,thepitchcircles(forstandardgears,thedividingline)ofthetwogearscoincideandaredrawnasadashedline.Therootlinesofbothgearsaredrawnasthicksolidlines,whilethetiplineofonegearisdrawnasathicksolidline,andthetiplineoftheothergearisdrawnasadashedlineoromittedaltogether.DrawingMethodattheMeshPoint0.25mTheclearancebetweenthetipandtherootis0.25m(wheremisthemodule).RegulatedDrawingMethodforGearMeshingSummaryofthislectureBasi