外文翻译(汽车差速器)

1、外文翻译（汽车差速器）FailureanalysisofanautomobiledifferentialpinionshaftAbstractDifferentialisusedtodecreasethespeedandtoprovidemomentincreasefortransmittingthemovementcomingfromtheenginetothewheelsbyturningitaccordingtothesuitableangleinvehiclesandtoprovidethatinnerandouterwheelsturndifferently.Piniongearan

2、dshaftattheentrancearemanufacturedasasinglepartwhereastheyareindifferentformsaccordingtoautomobiletypes.Mirrorgearwhichwillworkwiththisgearshouldbecomefamiliarbeforetheassembly.Incaseofanybreakdown,theyshouldbechangedasapair.Generally,inthesesystemsthereareweardamagesingears.Thegearinspectedinthisst

3、udyhasdamageasaformofshaftfracture.Inthisstudy,failureanalysisofthedifferentialpinionshaftiscarriedout.Mechanicalcharacteristicsofthematerialareobtainedfirst.Then,themicrostructureandchemicalcompositionsaredetermined.Somefractographicstudiesarecarriedouttoassesthefatigueandfractureconditions.Keyword

4、s:Differential;Fracture;Powertransfer;PinionshaftIntroductionThefinal-drivegearsmaybedirectlyorindirectlydrivenfromtheoutputgearingofthegearbox.Directlydrivenfinaldrivesareusedwhentheengineandtransmissionunitsarecombinedtogethertoformanintegralconstruction.Indirectlydrivenfinaldrivesareusedattherear

5、ofthevehiclebeingeithersprungandattachedtothebodystructureorunsprungandincorporatedintherear-axlecasing.Thefinal-drivegearsareusedinthetransmissionsystemforthefollowingreasons1:toredirectthedrivefromthegearboxorpropellershaftthrough90?and,toprovideapermanentgearreductionbetweentheengineandthedriving

6、road-wheels.Invehicles,differentialisthemainpartwhichtransmitsthemovementcomingfromtheenginetothewheels.Onasmoothroad,themovementcomestobothwheelsevenly.Theinnerwheelshouldturnlessandtheouterwheelshouldturnmoretodotheturningwithoutlateralslippingandbeingflung.Differential,whichisgenerallyplacedinthe

7、middlepartoftherearbridge,consistsofpiniongear,mirrorgear,differentialbox,twoaxlegearandtwopinionspidergears.AschematicillustrationofadifferentialisgiveninFig.1.ThetechnicaldrawingofthefracturedpinionshaftisalsogiveninFig.2.Fig.3showsthephotographofthefracturedpinionshaftandthefracturesectionisindic

8、ated.Indifferentials,mirrorandpiniongeararemadetogetusedtoeachotherduringmanufacturingandthesameserialnumberisgiven.Bothofthemarechangedonconditionthatthereareanyproblems.Inthesesystems,thecommondamageisthewearofgears2-4.Inthisstudy,thepinionshaftofthedifferentialofaminibushasbeeninspected.Theminibu

9、sisadieselvehicledrivenattherearaxleandhasapassengercapacityof15people.Maximumenginepoweris90/4000HP/rpm,andmaximumtorqueis205/1600Nm/rpm.Itstransmissionboxhasmanualsystem(5forward,1back).Thedamagewascausedbystoppingandstartingtheminibusatatrafficlights.Inthisdifferential,entranceshaftwhichcarriesth

10、epiniongearwasbroken.Variousstudieshavebeenmadetodeterminethetypeandpossiblereasonsofthedamage.Theseare:studiescarriedouttodeterminethematerialoftheshaft;studiescarriedouttodeterminethemicro-structure;studiesrelatedtothefracturesurface.ThereisacloserphotographofthefracturedsurfacesandfractureareainF

11、ig.4.Thefracturewascausedbytakingoutcircularmarkgearseeninthemiddleofsurfaces.Fig.1.Schematicoftheanalyseddifferential.TechnicaldrawingoftheanalysedpinionshaftThepictureoftheundamageddifferentialpinionanalysedinthestudyPhotographsoffailedshaftExperimentalprocedureSpecimensextractedfromtheshaftweresu

12、bjectedtovarioustestsincludinghardnesstestsandmetallographicandscanningelectronmicroscopyaswellasthedeterminationofchemicalcomposition.Alltestswerecarriedoutatroomtemperature.ChemicalandmetallurgicalanalysisChemicalanalysisofthefractureddifferentialmaterialwascarriedoutusingaspectrometer.Thechemical

13、compositionofthematerialisgiveninTable1.ChemicalcompositionshowsthatthematerialisalowalloycarburisingsteeloftheAISI8620type.Hardenabilityofthissteelisverylowbecauseoflowcarbonproportion.Therefore,surfaceareabecomeshardandhighlyenduring,andinnerareasbecomestoughbyincreasingcarbonproportiononthesurfac

14、eareawithcementationoperation.Thisisthekindofsteelwhichisgenerallyusedinmechanicalpartssubjecteddotorsionandbending.Highresistanceisobtainedonthesurfaceandhighfatigueendurancevaluecanbeobtainedwithcompressiveresidualstressbymakingthesurfaceharder5-7.Inwhichalloyelementsdistributethemselvesincarbonst

15、eelsdependsprimarilyonthecompound-andcarbide-formingtendenciesofeachelement.Nickeldissolvesintheaferriteofthesteelsinceithaslesstendencytoformcarbidesthaniron.Siliconcombinestoalimitedextentwiththeoxygenpresentinthesteeltoformnonmetallicinclusionsbutotherwisedissolvesintheferrite.Mostofthemanganesea

16、ddedtocarbonsteelsdissolvesintheferrite.Chromium,whichhasasomewhatstrongercarbide-formingtendencythaniron,partitionsbetweentheferriteandcarbidephases.Thedistributionofchromiumdependsontheamountofcarbonpresentandifotherstrongercarbide-formingelementssuchastitaniumandcolumbiumareabsent.Tungstenandmoly

17、bdenumcombinewithcarbontoformcarbidesifthereissufficientcarbonpresentandifotherstrongercarbide-formingelementssuchastitaniumandcolumbiumareabsent.Manganeseandnickellowertheeutectoidtemperature8.PreliminarymicrostructuralexaminationofthefaileddifferentialmaterialisshowninFig.5.Itcanbeseenthatthemater

18、ialhasamixedstructureinwhichsomeferriteexistprobablyasaresultofslowcoolingandhighSicontent.HighSicontentinthistypeofsteelimprovestheheattreatmentsusceptibilityaswellasanimprovementofyieldstrengthandmaximumstresswithoutanyreductionofductility9.Ifthemicrostructurecannotbeinvertedtomartensitebyquenchin

19、g,areductionoffatiguelimitisobserved.Table1Chemicalanalysisofthepiniongearmaterial(wt%)FeCSiMnPSCrMoNi96.920.2350.2520.7860.0440.0160.481ThereareareaswithcarbonphaseinFig.5(a).ThereisthetransitionboundaryofcarburisationinFig.5(b)and(c)showsthematrixregionwithoutcarburisation.Asfarasitisseenintheseph

20、otographs,thepiecewasfirstcarburised,thenthequenchingoperationwasdoneandthantempered.Thissituationcanbeunderstoodfromblindmartensiteplates.HardnesstestsThehardnessmeasurementsarecarriedoutbyaMetTest-HTtypecomputerintegratedhardnesstester.Theloadis1471N.Themediumhardnessvalueoftheinteriorregionsisobt

21、ainedas43HRC.Microhardnessmeasurementshavebeenmadetodeterminethechanceofhardnessvaluesalongthecross-sectionbecauseofthehardeningofsurfaceareaduetocarburisation.TheresultsofVickershardnessmeasurementunderaloadof4.903NareillustratedinTable2.InspectionofthefractureThedirectobservationsofthepiecewithfra

22、cturedsurfacesandSEManalysesaregiveninthischapter.Thecrackstartedbecauseofapossibleprobleminthebottomofnotchcausedtheshafttobebrokencompletely.Thecrackstartedontheouterpart,aftersometimeitcontinuedbeyondthecentreandtherewasonlyalittlepartleft.Andthispartwasbrokenstaticallyduringsuddenstartingoftheve

23、hicleatthetrafficlights.Asacharacteristicofthefatiguefracture,therearetworegionsinthefracturedsurface.Theseareasmoothsurfacecreatedbycrackpropagationandaroughsurfacecreatedbysuddenfracture.ThesetworegionscanbeseenclearlyfortheentireproblemasinFig.4.Thefatiguecrackpropagationregioncoversmorethan80%of

24、thecross-section.Table2MicrohardnessvaluesDistancefromsurface(Im)50100200400CenterValuesHV(4903N)588410293286263Fig.Fig.6.SEMimageofthefracturesurfaceshowingtheductileshear.Fig.7.SEMimageofthefracturesurfaceshowingthebeachmarksofthefatiguecrackpropagation.Shaftworksundertheeffectofbending,torsionand

25、axialforceswhichaffectrepeatedlydependingontheusageplace.Thereisasharpfilletatlevelonthefracturedsection.Forthisreason,stressconcentrationfactorsoftheareahavebeendetermined.Kt=2.4value(forbendingandtension)andKt=1.9value(fortorsion)havebeenacquiredaccordingtocalculations.Thesearequitehighvaluesforar

26、easexposedtocombinedloading.Theseobservationsandanalysisshowthatthepiecewasbrokenundertheinfluenceoftorsionwithlownominalstressesandmediumstressconcentration10.Thescanningelectronmicroscopyshowsthatthefracturehastakenplaceinaductilemanner(Fig.6).Therearesomeshearlipsinthecrackpropagationregionwhichi

27、saglueoftheplasticsheardeformations.Fig.7showsthebeachmarksofthefatiguecrackpropagation.Thedistancebetweenanytwolinesisnearly133nm.3.ConclusionsAfaileddifferentialpinionshaftisanalysedinthisstudy.ThepinionshaftisproducedfromAISI8620lowcarboncarburisingsteelwhichhadacarburising,quenchingandtemperingh

28、eattreatmentprocess.Mechanicalproperties,microstructuralproperties,chemicalcompositionsandfractographicanalysesarecarriedouttodeterminethepossiblefracturereasonsofthecomponent.Asaconclusion,thefollowingstatementscanbedrawn:Thefracturehastakenplaceataregionhavingahighstressconcentrationbyafatigueproc

29、edureunderacombinedbending,torsionandaxialstresseshavinghighlyreversiblenature.Thecrackofthefractureisinitiatedprobablyatamaterialdefectregionatthecriticallocation.Thefractureistakenplaceinaductilemanner.Possiblelaterfailuresmayeasilybepreventedbyreducingthestressconcentrationatthecriticallocation.A

30、cknowledgementTheauthorisveryindebtedtoProf.S.Tasgetirenforhisadviceandrecommendationsduringthestudy.H.Bayrakceken/EngineeringFailureAnalysis13(2006)1422-1428ReferencesHeislerH.Vehicleandenginetechnology.2nded.London:SAEInternational;1999.MakevetE,RomanI.Failureanalysisofafinaldrivetransmissioninoff

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32、lebMJ.Failuresofrearaxleshaftsof575DItractors.EngFailureAnal2003;10:719-24.AslantasK,TasgetirenS.Astudyofspurgearpittingformationandlifeprediction.Wear2004;257:116775.SavasV,O?zekC.Investigationofthedistributionoftemperatureonashaftwithrespecttothedeflection.TechnolRes:EJMT2005;1:33-8.SmithFW.Princi

33、plesofmaterialsscienceandengineering.3rded.USA:McGraw-HillSeries;1996.p.517-18.ASMmetalhandbook,vol.1.Propertiesandselection,irons,steels,andhighperformancealloys;1991.VoortGFV.Visualexaminationandlightmicroscopy.ASMhandbookmetallographyandmicrostructures.MaterialsPark(OH):ASMInternational;1991.p.10

34、0-65.汽车差速器小齿轮轴的失效分析摘要差速器的作用是根据车辆合适的角度,通过将运动转向,为运动传输减速或者提供瞬间加速,这个运动来自引擎,到车轮去,使内外车轮转动不同。开口处的游星齿轮和轮轴是作为单一零件的，但是根据车辆型号有不同的形状。和这个齿轮一起工作的镜面齿轮应该在组装前就磨合好。一旦发生故障，它们应该成对更换。一般来说，在这些系统中齿轮都存在磨损损坏。本文中检查的齿轮损坏具体说是轮轴断裂。本研究进行了差速器小齿轮轴的失效分析。首先，取得材料的机械特点，然后确定其微观结构和化学成分，还要做一些显微镜观察研究来评估其疲劳和破损状况。关键词:差速器;破损;动力分配装置;小齿轮轴简介最终传

35、动齿轮可能直接或间接地由齿轮箱的输出齿轮驱动。当引擎和传输设备结合在一起，形成统一结构时，就需要使用直接驱动的最终传动齿轮。间接驱动最终传动齿轮或者借助一些装置附在汽车后端，或者并入后桥壳。最终驱动齿轮由于如下原因被使用在传输系统中:6)为了使齿轮箱或者传动轴的动力90?转向(2为了提供引擎和驱动轮之间永久的齿轮减速。在汽车中，差速器是将运动从引擎传输到车轮的主要部件。在平坦的道路上，运动会平均分配给两个轮子。内侧车轮应该程度小一些,外侧车轮转向程度应该大一些,这样转弯才不会侧滑。差速器通常置于后桥中部，由游星齿轮、镜面齿轮、差速器箱、轴齿轮和两个游星蜘蛛齿轮构成。图表一是差速器的示意图，图表

36、二是断裂的小齿轮轴的技术图解，图表三是断裂的小齿轮轴的图片，表示出了断裂部分。在差速器里，人们生产时将镜面和流星齿轮制作得相互适应，并且使用相同的序列号。出现问题的话，二者都要更换。在这些系统中，常见的损伤是齿轮磨损。本研究检查了一辆小型巴士的差速器小齿轮轴。该小型巴士是后轴驱动的柴油汽车，可搭载15名乘客。发动机最大功率是，最大扭转力是。传动箱里有手动系统（5个向前，一个向后）。损伤是由巴士在交通灯出停止和启动引起的。在差速器中，驱动流星齿轮的输入轴断裂。人们做了各种各样的研究来确定这种损伤的类型和可能的原因。它们是：确定轮轴材料的研究确定微观结构的研究与断裂面相关的研究图四是断裂表面和断裂

37、区域的近距离照片。这个断裂是将表面中心的圆形标记齿轮取走形成的。半轴太阳轮行星齿轮齿轮轴十字销镜面齿轮图1进行分析的差速器的图解图2进行分析的小齿轮轴的技术图解图2进行分析的小齿轮轴的技术图解失效十字部分图3研究中进行分析的完好小齿轮轴的图片静态断裂裂纹扩展区域区域图4失效轮轴的照片实验步骤金相和扫描电子从轮轴中取得的样本要接受各种各样的测试，包括硬度测试，显微镜以及化学成分的确定。左右测试均在室温下进行。金相和扫描电子化学和冶金分析断裂差速器材料的化学分析是使用光谱仪完成的。该材料的化学成分如表一所示。化学成分显示该材料是美国钢铁协会8620型的一种低合金碳化钢。这种钢的淬硬性很低，因为碳含

38、量比例较低。因而，需要通过渗碳处理增加表面区域的碳比例，使表面区域变得坚硬，非常耐用，内部区域变得坚韧。这种钢一般用在需要扭转和弯曲的机械部件中。通过使表面变硬，用残余应力使表面获得高阻力性，获得高疲劳承受值。合金元素怎样掺入碳钢主要取决于每种元素的化合倾向和形成碳化物的倾向。镇溶解于钢的铁酸盐，因为它比铁更不容易形成碳化物。硅与钢中的氧在一定程度上结合形成非金属内含物，不然的话则溶于铁酸盐。铭比铁更容易形成碳化物一些，会在铁酸盐和碳化物阶段之间分解。掺入铭取决于碳含量以及是否没有钛、轲这样更易形成碳化物的元素存在。如果有足够的碳并且没有钛、轲这样更易形成碳化物的元素存在，鸨和铝可以和碳形成碳

39、化物。镒和镇可以降低共析混合物的温度。失效差速器材料的初步微观检验如图五所示。可以看出这种材料有一种复合结构，由于缓慢冷却和较高的硅含量，该结构中很可能存在铁酸盐。这种钢中的高硅含量可以提高受热敏感性还有提高屈服强度和最大压力，而不降低延展性。如果微观结构不能通过冷淬转化为马氏体，就可以观察到疲劳极限降低。表1流星齿轮材料的化学分析渗碳区域过渡区域扩散区域图5该材料的微观结构图5(a)中有处于碳阶段的区域。图五(b)中有渗碳的过渡边缘，(c)显示了未渗碳的基质区域，而后进行冷淬操作，接着再回火。这种情形可以从不易观察到的马氏体片来理解。2(2硬度测试硬度测试时通过MetTest-HT型计算机集

40、成硬度测试器进行的。其负荷为14N。内部区域的平均硬度值为43HRC，并进行了微观硬度测试，以确定渗碳引起的表面的硬化带来的横截面硬度值的变化。在4.903N的负荷量下，维式硬度计硬度测试的结果如表2所示。2.3断裂处的检查本章给出了表面断裂的轮轴的直接观察结果和扫描式电子显微镜分析结果。刻痕底部可能的问题导致出现裂缝，使整个轮轴完全断裂。裂缝在外部开始，过一段时间断裂范围越过中心部分，只剩一小部分没有断裂。而这一部分也会在车辆在交通灯处突然启动时静止断裂。在断裂表面有两个区域，这是疲劳断裂的一个特点。有一个裂缝扩大引起的光滑表面和一个突然断裂引起的粗糙表面。这两个区域可以在图4的问题中清楚地

41、看到。疲劳裂缝扩大区域占横截面的80%。表2微观硬度值图6显示出断裂表面韧性剪切带的扫描式电子显微镜图像图7显示疲劳裂缝扩散海滩纹的断裂表面的扫描电子显微镜图像轮轴在弯曲、扭转、轴向力的作用下工作，弯曲、扭转、轴线力不断影响依赖使用区域。在断裂部分有一个锋利的薄片，这样就可以确定该区域的压力集中因素。根据计算，得知弯曲和压力的Kt值为2.4,扭转的Kt值为1.9。对于承受组合负荷的区域这些数值是相当高的。这些观察和分析显示，轮轴在很少压力，中等压力集中的情况下，受扭转影响而断裂。扫描电子显微镜显示，断裂是延展的状态下发生的（图6）。在裂缝扩散区域有一些切变裂痕，切变裂痕总是伴随切变形发生。图7显示了疲劳裂缝扩散的海滩纹。任何两条纹之间都在133纳米左右。3.结论本文分析了失效的差速器小齿轮轴。小齿轮轴是用美国钢铁协会8620低碳渗碳钢生产的，这种钢经过渗碳、冷淬和回火热处理过程。进行了机械性质、微观结构性质