68齿轮

Chap.8Spurgears,Keys,Pins,Springs,andAntifrictionBearings齿轮,键,销,弹簧和减摩轴承(滚动轴承)key键pin销spring滚动轴承gear齿轮shafthole轴孔hub轮毂spoke轮幅web幅板rim轮缘keywayorkeyslot键槽Keywords:8.1.1Functionandclassificationofgears齿轮的功能及分类8.1.2Toothedgearing带齿的轮子8.1.3Termsandformulasforspurgears圆柱直齿轮的术语及计算公式8.1.4Geardrawings齿轮的画法8.1.1Functionandclassificationofgears齿轮的功能及分类Gearsaremachineelementsusedtotransmitmotionorforce.Therearemanykindsofgearssuchasspurgears(圆柱齿轮),bevelgears(圆锥齿轮)andwormgears(蜗轮蜗杆).Inwhichspurgearsarethemostimportantones.Whenpoweristransmitted(传递)fromoneshaft(轴)toaparallel(平行的)shaft,thespurgearsareused.Spurgearandrack(齿条)canbeusedtochange(旋转的)motiontolinear(线性的)motion.Bevelgearsareusedforshaftswhoseaxesintersect(相交),andwormgearsfornonintersecting(交叉的)shaftsatrightangletoeachother.8.1.2ToothedgearingGearsevolved(发展,进化)fromtheancientfrictionwheels(古老的摩擦轮).Iftwowheelsorcirculardisks(圆盘)areincontactasinthefigurebothwillrevolve(旋转)ifoneisturned.Ifthesmallerwheelistwo-thirds(1/3)thediameter(直径)ofthelargerwheel,itwillmakeoneandahalfrevolutions(一圈半)foronerevolutionofthelargerwheelifnoslipping(滑动)occurs.Ifthedrivenwheel(驱动轮)ishardtoturn,therewillbeslipping.Topreventthis,teethareaddedtothewheelstoformspurgears.Toothedgearingisapositivemeansoftransmittinghigh–torque(扭矩)loadfromoneshafttoanotherataconstantvelocity(速度)ratio.Involute(渐开线)andcycloidal(摆线)curvesareusedforgearteethforms,andtheinvoluteonesareusedmostwidely.shafthole(轴孔)hub(轮毂)spoke(轮幅)web(幅板)rim(轮缘)keywayorkeyslot(键槽)平板齿轮带轮毂齿轮8.1.3Termsandformulasforspurgears圆柱直齿轮的术语及计算公式D0(da)=outdiameter齿顶圆直径diameterofthecirclecontainingthetopsurfacesoftheteeth.Dr(df)=rootdiameter齿根圆直径diameterofthecirclecontainingthebottomsurfacesofthetoothspaces.Db(d')=basediameter分度圆直径diameterofthecirclefromwhichtheinvolute(渐开线)isgenerated.Dp(d)=pitchdiameter节圆直径diameterofthecirclecorresponding(相应的)tothediameterofthefrictionwheels.Forstandardgearsd'=d.t(p)=circularpitch齿距thedistancefromapointononetoothtothecorrespondingpointonthenexttoothmeasuredalongthepitchcircle.s(s)=tooththickness齿厚thethicknessofatoothmeasuredalongthepitchdiametercircle,s=t(p)/2.w(e)=toothspace槽宽thespacebetweentwoteethmeasuredalongthepitchdiametercircle,w=t(p)/2,t(p)=s+w(e).h1(ha)=addendum齿顶高radialdistancebetweenthepitchdiametercircleandthetopofatooth.h2(hf)=dedendum齿根高radialdistancebetweenthepitchdiametercircleandthebottomofatooth.h(全齿高)=h1+h2(ha+hf)F=facewidth齿宽widthofthetoothflank(侧面).c=clearance顶隙radialdistancebetweenthetopofatoothandthebottomofamating(啮合的)toothspace.D=workingdepth工作深度greatestdepthatoothofonegearextendstoatoothspaceofamatinggear.D=h-c.Z=numberofteeth(Z1,Z2)齿数▲A(a)=thedistanceoftwocenters.（中心距）m(模数)=module=t/π(p/π)∵p×Z=π×d∴d=(p/π)×Zd=m×ZThevaluesofmodulehavealreadybeenstandardizedbyGB,asshowninTab.8-1.0.10.150.20.250.30.40.50.60.811.251.522.534568101214161820222530364045500.71.752.25(2.75)(3.25)3.5(3.75)4.5(5.5)(6.5)79(11)(13)(15)2833Tab.8-1StandardmodulesFirstseriesseriesSecondNote:Whenselectingthemodule,thefirstseriesshouldbepreferred.Themodulesinbrackets(括号)areseldomusedunlessnecessary.Moduleisoneoftheimportantelementsingearteeth.Severalusefulformulasareallbasedonit.d=m×Z8.1.4Formulas公式Forastandardspurgear,thefollowingformulasmaybesetup.d=m×Zha=mhf=1.25mh=ha+hf=2.25mda=m(Z+2)df=m(Z-2.5)▲A=(d1+d2)/2=m(Z1+Z2)/28.1.4Geardrawings齿轮的画法(1)Conventionalrepresentation规定画法Itisnotnecessarytoshowtheteethondrawingsofgears.Theycanbedrawnbyaconventionalcircle-arcmethod,i.e.toshowtheoutsidediameterwithafullline,thepitchdiameterwithacenterline,andtherootdiameterwithathinline.Frequentlytherootdiametercanbeomitted(省略).平板齿轮不剖及剖视画法带轮毂齿轮的剖视及斜齿轮的画法单个齿轮的简化画法(2)Inadetaildrawing齿轮零件图Theworkingdrawingofaspurgearisshowninthefigure.α(3)Inanassemblydrawing齿轮啮合图Thedrawingoftwomatinggearsisshowninthefigure.Thesmalloneisoftencalledpinion(小齿轮).不剖画法剖视画法Notethattwomating(啮合)gearswillbetangent(相切)atacertainpointcommontobothpitchdiametercircles(节圆),andthemodule(模数),thecircularpitch(节距),theaddendum(齿顶高),thededendum(齿根高),etc.areallequal.shafthole(轴孔)hub(轮毂)spoke(轮幅)web(幅板)rim(轮缘)keywayorkeyslot(键槽)