拖拉机后桥半轴套车削加工夹具设计【车右端面】【说明书+CAD】
收藏
资源目录
压缩包内文档预览：
编号：120955191
类型：共享资源
大小：929.14KB
格式：ZIP
上传时间：2021-04-11
上传人：221589****qq.com
认证信息
个人认证
李**（实名认证）
湖南
IP属地：湖南
40
积分
- 关 键 词：
-
车右端面
拖拉机
后桥
轴套
车削
加工
夹具
设计
端面
说明书
CAD
- 资源描述：
-
拖拉机后桥半轴套车削加工夹具设计【车右端面】【说明书+CAD】,车右端面,拖拉机,后桥,轴套,车削,加工,夹具,设计,端面,说明书,CAD
- 内容简介：
-
江西农业大学工学院,拖拉机半轴套车床夹具设计 机制05（2）班 黄阁锋,前 言,夹具是机械加工不可缺少的部件，在机床技术向高速、高效、精密、复合、智能、环保方向发展的带动下，夹具技术正朝着高精、高效、模块、组合、通用、经济方向发展。 高精：随着机床加工精度的提高，为了降低定位误差，提高加工精度，对夹具的制造精度要求更高。德国demmeler(戴美乐)公司制造的4m长、2m宽的孔系列组合焊接夹具平台，其等高误差为0.03mm；精密平口钳的平行度和垂直度在5m以内；夹具重复安装的定位精度高达5m。机床夹具的精度已提高到微米级，世界知名的夹具制造公司都是精密机械制造企业。诚然，为了适应不同行业的需求和经济性，夹具有不同的型号，以及不同档次的精度标准供选择。,高效：为了提高机床的生产效率，双面、四面和多件装夹的夹具产品越来越多。为了减少工件的安装时间，各种快速夹紧功能部件不断地推陈出新。新型的电控永磁夹具，加紧和松开工件只用12秒，夹具结构简化，为机床进行多工位、多面和多件加工创造了条件。为了缩短在机床上安装与调整夹具的时间，瑞典3R夹具仅用1分钟，即可完成线切割机床夹具的安装与校正。,模块、组合：模块化设计为夹具的计算机辅助设计与组装打下基础，应用CAD技术，可建立元件库、典型夹具库、标准和用户使用档案库，进行夹具优化设计，为用户三维实体组装夹具。组合夹具分会与华中科技大学合作，正在着手创建夹具专业技术网站，为夹具行业提供信息交流、夹具产品咨询与开发的公共平台，争取实现夹具设计与服务的通用化、远程信息化和经营电子商务化。 通用、经济：夹具的通用性直接影响其经济性。采用模块、组合式的夹具系统，一次性投资比较大，只有夹具系统的可重组性、可重构性及可扩展性功能强，应用范围广，通用性好，夹具利用率高，收回投资快，才能体现出经济性好。德国demmeler(戴美乐)公司的孔系列组合焊接夹具，仅用品种、规格很少的配套元件，即能组装成多种多样的焊接夹具。元件的功能强，使得夹具的通用性好，元件少而精，配套的费用低，经济实用才有推广应用的价值。 本设计也是遵循以上夹具技术的发展方向，围绕高效、通用、经济而进行设计的。,设计题目 由拖拉机半轴套零件图可知零件的基本结构和加工要求。该工件铸成后（铸件图参见附录）需车削四个端面和两个外圆，并满足各端面的平面度和垂直度的要求及两外圆的同轴度要求,为后期加工提供较好的定位基准。车削后需铣削三个端面，其中两个是为了钻孔而做的前期工作，而有10度倾角要求的端面是零件图中的要求。端面车削好后需对两个端面钻通孔，各端面孔的位置要求为均布，并且为了保证连接紧凑，法兰面不光滑平整的情况下需要在通孔周围刮深0.518的孔。在前期车好端面和钻好孔的情况下，可以方便的利用其对钻两排孔进行定位。 加工该零件的夹具设计由谢李华、朱敏芳及本人组成的三人小组负责设计。其中本人负责车床夹具的设计。,图（一）是拖拉机半轴套车削的工序图，该零件是中批量生产，现要求设计车削该零件四个端面和两外圆的车床夹具。其中两端面和外圆的粗糙度要求是6.3，另外两端面的粗糙度要求是3.2，两外圆的直径分别是mm和mm。且应保证图中的相应面的平面度和垂直度及两外圆的同轴度的要求。,具体步骤如下： 1 工件的加工工艺分析. 按照常规的车削方法先车端面再车外圆。其中端面粗糙度要求为6.3的两端面比较容易完成，可通过粗车完成。粗糙度要求为3.2的两端面因为有平面度0.06mm和垂直度0.08mm的要求，所以需在完成车外圆后才能加工出来。两外圆的尺寸分别为mm和mm，且还有同轴度0.1mm的要求，所以最好是在一次装夹中完成以满足该精度的要求。但考虑到加工可取性，本人选择了两次加工完成，详解后续。另外为了配合该零件的后期钻孔加工，对F平面有一个平面度为0.06mm的要求。,基于以上精度要求，再结合零件图上个各尺寸要求的工序基准，初步把整个加工工艺工程表示成下表,2 夹具结构方案的确定 2.1定位方案选择及定位元件设计： 方案一： 对套类零件，为了简化定心定位装置，常常采用刚性心轴作为定位元件。因为工件的端面还未加工故不能用带有凸肩的心轴，即在夹紧装置的设计上不能使用拉杆。而工件的内孔直径呈中间大两头小分布，所以只能靠两端的小孔来定位并通过与圆孔的过盈配合来夹紧。示意图如图（二）。限定工件六个自由度。心轴上的键是用来传递扭矩，带动工件和车床主轴一起转动。心轴左端用于与鸡形夹抓紧。同时其轴心线也是夹具体和车床定位的一个基准。,图 （ 二 ）,如此设计则可在一次装夹完成上述对工件各端面和外圆的加工。但由于定位基准是两端的内壁且夹紧是通过过盈配合，所以虽然该心轴的定位精度高但装卸工件麻烦，生产效率较低。且由于工件为铸件，内壁精度很低，容易引起夹紧不可靠。,方案二： 用螺丝来代替夹紧，在车左端面方面，装夹不用螺母、垫圈和左边的锥套固定，因为如果用左边的锥套固定，那么锥套将会复盖一部分在端面，使左端面加工不完全，等车完左端面再地行第二次装夹，加上螺母，这样就不会影响加工，因为车左端面时要求较低。粗车就可达到粗糙度6.3的要求，且对平面度和垂直度没有要求，所以只用三抓卡盘定位及夹紧即可。为了保证工件在转动时候的安全，可在工件中间部分用中心架顶住，但由于工件表面是一个锥体，且还是铸件，所以中心架的顶杆并不与工件接触只是起保护作用，防止工件由于旋转而甩出。 在车右端面方面，由于其有粗糙度6.3的要求，还为了配合后期的钻孔的定位所以有平面度0.06mm的要求，再结合左端面的外形结构，故把该工序的夹具和车外圆的夹具合在一起。使得车右端面和车外圆在一次装夹完成。,在车外圆方面，由于有同轴度0.1mm的要求，而其外形方面却又找不到合适的定位基准，故以工件上的内孔作为定位基准。但由于工件本身为铸件，内部的尺寸精度不高，故以其内孔两端的截面圆心的连线为定位基准。定位元件采用定位套。如图（三）所示。这样限定了工件的六个自由度。 在车大端面方面，为了减少工件的安装时间，且保证其平面度0.06mm和垂直度0.08mm的要求，故仍以内孔两端的截面圆心的连线为定位基准。该工序的夹具也和车外圆的的夹具合在一起。使得车端面和车外圆可在一次装夹内完成。提高装夹的效率。,图（三）,1- 心轴 2- 锥套 3- 垫圈 4- 螺母,2.2夹紧方案选择及夹紧机构设计 2.2.1夹具与工件的夹紧方案选择及夹紧机构设计 方案一： 如图（二）通过心轴与工件内壁的过盈配合夹紧，设计简单，心轴的制作也简单。但装卸工件时比较麻烦，生产效率也较低，且由于工件内壁精度不高，故夹紧不可靠。 方案二： 螺旋夹紧机构简单，夹紧可靠，通用性大，且结合工件的形状，故该设计使用螺旋加紧机构夹紧。如图（三）,心轴1上有一锥台用于右端定位，锥台的锥面上开有键槽，当心轴加工好后把键焊接在键槽内；心轴左端为螺杆结构，具体尺寸见（零件图一）。锥套2用于左端定位，并在锥面上开有键槽，当锥套加工好后把键焊接在键槽内，使得其和心轴上的键配合传递扭矩。具体尺寸见（零件图二、三）。垫圈3和螺母4起夹紧作用，具体尺寸见（零件图四、五）。这样的机构既能起到夹紧的功能，也有自动定心的功能。虽然要装夹两次，但第二次装夹很简单，在很短的时间内就可以完成，而且在装夹时不会影响后面的的精确度，在装卸方便时，也提高了生产效率。 此外，通过使用不同规格的锥套与此心轴配合可加工不同尺寸的套类零件。可小幅度的实现其通用性并提高此使用夹具的经济性。,2.2.2夹具与机床的加紧方案选择及加紧机构设计 两套方案的夹具在车床上的定位都是以三爪卡盘夹住夹具体，再通过尾座顶尖与心轴的顶尖孔的接触来实现的 三抓卡盘和尾座顶尖是通用夹具，因此不需专门设计，可根据生产的实际情况选择适当型号的三爪卡盘和尾座顶尖。故在总装图中不画出。,两个方案的比较优劣可由下表比较表示出,由上表对比可知，选用方案二较为妥善。,为此，根据以上情况，可以确定整个加工工艺工程表示如下表,3 加紧机构的相关计算 3.1切削力的计算 刀具在切削工件时，存在切屑与工件内部弹、塑性变形的抗力；切屑与工件对刀具产生的摩擦阻力；两者作用在刀具上的合力为F。为了测量、计算和反映实际作用的需要，可将合力F分解为三个分力： 切削力Fc在主运动方向上的分力； 背向力Fp在垂直于假定工作平面上分力； 进给力Ff在进给运动方向上的分力；,根据切削力实验公式 Fc、Fp、Ff各切削分力，单位为N； 、公式中系数，根据加工条件由实验确定；查表确定分别为2795、1940、2880； xf、yf、nf 表示各因素对切削力的影响程度指数；查表的Fc的各指数为1.0、0.75、-0.15；Fp的各指数为0.90、0.6、-0.3；Ff的各指数为1.0、0.5、-0.4； 、不同加工条件对各切削力的影响修正指数，暂设加工条件比较理想各修正指数为1。 计算得Fc=18067 N Fp=8130 N Ff=6323 N,3.2加紧力的计算 3.2.1三抓卡盘夹紧力的计算 计算夹紧力时,通常将夹具和工件看成是一个刚性系统.根据工件受切削力,夹紧力(大型工件还应考虑工件重力,运动的工件还应考虑惯性力等)的作用情况,找出在加工过程中对夹紧最不利的瞬时状态,按静力平衡原理计算出理论夹紧力.最后为保证夹紧可靠,再乘于安全系数作为实际所需夹紧力的数值.即: WK -实际所需夹紧力(N); W-在一定条件下,由静力平衡计算出的理论夹紧力(N); K-安全系数.,3.2.1.1理论夹紧力可用如下公式计算： 为工件与支撑表面的摩擦系数取0.2 3.2.1.2安全系数K的式计算: 计算得： W=1694,3.2.2螺旋夹紧机构的夹紧力的计算。 其中本夹具机构采用的夹紧装置是螺旋夹紧机构:该类夹紧机构结构简单,夹紧可靠,通用性大,故在机床夹具中得到广泛应用.它的主要缺点是与液压机构相比该机构在夹紧和松开工件时比较费时和费力; 经计算的，具满足刚度和强度要求。 3.3定位误差的计算 4 确定夹具的主要尺寸、公差和技术要求 4.1夹具总图上应标的尺寸及公差 （1）心轴的总长和各部分的截面直径 （2）锥套的定位面尺寸及其他结构尺寸 （3）锥套与心轴的配合为零间隙配合为佳 详见附录中总装图。,各零件的三维实体图如下 铸件三维实体图,锥套三维实体图,锥套三维实体图（焊接键以后）,垫圈三维实体图,螺母三维实体图,心轴三维实体图,心轴三维实体图（焊接键以后）,总装三维示意图,5.结束语 通过将近三那个月的毕业设计，使我在资料的准备、设计的规划、市场的调查、创新思维和自学能力等方面都有了较大的提高。并且在毕业前使个人能力有了一个飞跃。 感谢曾一凡老师对我的论文不厌其烦的细心指点。曾老师首先细致地为我解题；当我迷茫于众多的资料时，他又为我提纲挈领，梳理脉络，使我确立了本文的框架。论文写作中，定期得到曾老师的指点。从框架的完善，到内容的扩充；从行文的用语，到格式的规范，曾老师都严格要求，力求完美。我再次为曾老师的付出表示感谢。 另外,在设计过程中, 有很多专业老师曾对本设计的完成提供了有力的帮助，在此，一并表示感谢。在设计中,由于本人的水平有限,必会有很多的不足之处,谨请各位老师批评指正.,6.参考文献 机床夹具设计 哈尔滨工业大学出版社 1996年2月第2版 机床夹具设计手册上海科学技术出版社 1988年4月第2版 金属切削机床夹具设计手册机械工业出版社 1987年12月第2版 金属切削原理与刀具 机械工业出版社 2005年7月第2版 金属机械加工工艺人员手册上海科学技术出版社1981年10月第2版 机械设计 高等教育出版社 2001年7月第1版 简明机械设计手册 上海科学技术出版社 2000年10月第2版, 江西农业大学工学院课题名称: 拖拉机后桥半轴套车削加工夹具设计 课题类型： 设 计 应 用 专 业： 机械设计制造及其自动化 班 级： 机制052班 姓 名： 黄 阁 锋 指导老师： 曾 一 凡 2009 年 5 月 目 录前言1设计题目21工件加工工艺分析32夹具结构方案的确定32.1定位方案选择及定位元件设计32.2夹紧方案选择及夹紧机构设计52.2.1夹具与工件的夹紧方案选择及夹紧机构设计62.2.2夹具与机床的加紧方案选择及加紧机构设计63 加紧机构的相关计算73.1切削力的计算73.2加紧力的计算83.2.1三抓卡盘夹紧力的计算83.2.1.1理论夹紧力可用如下公式计算93.2.1.2安全系数K的计算93.2.2螺旋夹紧机构夹紧力的计算93.3定位误差的计算104 确定夹具的主要尺寸、公差和技术要求114.1夹具总图上应标尺寸，公差11附录结束语参考资料江西农业大学机 械 加 工 工 序 卡产品型号BZK01零件图号 33431A102产品名称半轴壳零件名称半轴壳共1 页第1 页车 间工序号工序名称材料牌号大金工X2铣端面QT40015毛坯种类毛坯外形尺寸每毛坯件数每台件数铸造件313x16811设备名称设备型号设备编号同时加工件数立式铣床X53T1夹 具 编 号夹 具 名 称铣床专用夹具切削液工序工时准终单件 20min工步号工 步 内 容工 艺 装 备主轴转速(r/min)切削速度(m/min)进给速度(mm/r)切削量(mm)进给次数工步工时机动min辅助minX2-1车左端面普通车刀、满足粗糙度6。3 1440026690093 2344X2-2车右端面普通车刀、1440 0320280.093 3 3 4 2X2-3车两外圆普通车刀1440。0.09333 33X2-4车两大端面普通车刀1440。00503333设计（日期）审核（日期）标准化（日期）会签（日期）校对（日期）标记处数更改文件号签字日期标记更改文件号签字日期铸件三维实体图锥套三维实体图锥套三维实体图（焊接键以后）垫圈三维实体图螺母三维实体图心轴三维实体图心轴三维实体图（焊接键以后）总装三维示意图Failure analysis of an automobile differential pinion shaftAbstractDifferential is used to decrease the speed and to provide moment increase for transmitting the movement coming from the engine to the wheels by turning it according to the suitable angle in vehicles and to provide that inner and outer wheels turn differently. Pinion gear and shaft at the entrance are manufactured as a single part whereas they are in different forms according to automobile types. Mirror gear which will work with this gear should become familiar before the assembly. In case of any breakdown, they should be changed as a pair. Generally, in these systems there are wear damages in gears. The gear inspected in this study has damage as a form of shaft fracture.n this study, failure analysis of the differential pinion shaft is carried out. Mechanical characteristics of the material are obtained first. Then, the microstructure and chemical compositions are determined. Some fractographic studies are carried out to asses the fatigue and fracture conditions.Keywords: Differential; Fracture; Power transfer; Pinion shaftIntroductionBy ordinary differential planetary gear, the planet round rack (differential shell) and half axle gears, etc parts. By the power of the engine, direct drive shaft into differential planetary wheel frame, again by the planets wheel drive left, right, two half shaft are respectively driven wheels left and right. Differential design requirements meet: (left) + (right shaft speed shaft speed) = 2 (planets wheel frame speed). When the automobile moher, left, right wheel and planetary wheel frame three speed equal in balance, while in the car when turning three equilibrium state is destroyed, cause the medial wheel speed decreases, and the lateral wheel RPM increases. Automotive differential is driven axle Lord pieces. Its function is to both sides half shaft transmission power, while allowing both sides half shaft in different speed rotating, satisfy both sides wheel as pure rolling forms do isometric driving, reducing tire and the surface friction. Differential this adjustment is automatic, here involves minimal energy consumption principle, namely earth all objects are inclined to consumption minimum state. For example a grain of beans into a bowl, beans will automatically stays in the bowl bottom and never stay in bowl wall, because bowl bottom is lowest energy position (potential), it automatically select static (minimum) without constantly kinetic energy movement. In the same way, Wheel in cornering would also automatically tendency of the lowest energy consumption in accordance with state, automatically turning radius adjusting right wheels speed. 1 Below is a brief introduce two differential1 . Off differentialThe structure of the Cherokee open-die differential is typical of planetary gear set structure, only the sun wheel and the number of teeth gear ring outside are the same. In this planetary gear set, active wheel is the planet frame, passive round is two SUNS chakra. Through the planetary gear set transmission properties we know, if planet shelf as ZhuDongZhou, two SUNS rounds of speed and rotation direction is uncertain, even two SUNS rounds of rotation direction is the opposite.Vehicle condition, this differential went to feature is two and a half shaft transmission torque is same. In a drive wheels impending cases, if transmission shaft is uniform rotation, have the drive wheels is no adhesion of driving force transmission speed rotation, if there is the driving wheels, adhesion driving wheels Angle acceleration is equal to the impending product and moment of inertia.Vehicle turn tires dont skid condition, differential connection of two and a half shaft torque direction is instead, give the vehicle driving forward, only the inside of the wheel, the planet shelf and medial sun round by constant transmission between became deceleration transmission, driving sensation is accelerated speed curve more powerful than straight.The advantages of open differential is installed in the pavement turned the best effect. Driving Weakness is in a drive wheels, under the situation of loss of adhesion another no driving force.2. Limited slip differential Limited slip differential used for parts make up open-die differential transmission in off-road defects, it is in the open differential institution improved, and the differential shell side increase friction between gear piece, corresponding to the planetary gear set speaking, is the planet shelf and the sun round between increased friction slices, increase the sun wheel and planet shelf free rotating resistance torque. Limited slip differential provide additional torque, and friction slices transfer of power and two driving wheel rotation difference of concerned. In open-die differential structure to improve on LSD, cannot produce 100% limited slip, because the limited slip coefficient, the higher the vehicles to the characteristics of the poor. LSD have open-die differential transmission characteristics and mechanical structure. Advantage is to provide certain limited slip torque, defect is turning performance becomes poor, friction slices limited life. LSD is the suitable scope paving road surface and mild off-road. Usually used for the drive. Former drove generally does not installed, because LSD interfere steering, limited slip coefficient, the greater the steering the more difficult. The final-drive gears may be directly or indirectly driven from the output gearing of the gearbox. Directly driven final drives are used when the engine and transmission units are combined together to form an integral construction. Indirectly driven final drives are used at the rear of the vehicle being either sprung and attached to the body structure or unsprung and incorporated in the rear-axle casing. The final-drive gears are used in the transmission system for the following reasons 1:(a) to redirect the drive from the gearbox or propeller shaft through 90_ and,(b) to provide a permanent gear reduction between the engine and the driving road-wheels.In vehicles, differential is the main part which transmits the movement coming from the engine to the wheels. On a smooth road, the movement comes to both wheels evenly. The inner wheel should turn less and the outer wheel should turn more to do the turning without lateral slipping and being flung. Differential, which is generally placed in the middle part of the rear bridge, consists of pinion gear, mirror gear, differential box, two axle gear and two pinion spider gears.A schematic illustration of a differential is given in Fig. 1. The technical drawing of the fractured pinion shaft is also given in Fig. 2. Fig. 3 shows the photograph of the fractured pinion shaft and the fracture sectionis indicated.In differentials, mirror and pinion gear are made to get used to each other during manufacturing and the same serial number is given. Both of them are changed on condition that there are any problems. In these systems, the common damage is the wear of gears 24. In this study, the pinion shaft of the differential of aminibus has been inspected. The minibus is a diesel vehicle driven at the rear axle and has a passenger capacity of 15 people. Maximum engine power is 90/4000 HP/rpm, and maximum torque is 205/1600 Nm/rpm. Its transmission box has manual system (5 forward, 1 back). The damage was caused by stopping and starting the minibus at a traffic lights. In this differential, entrance shaft which carries the pinion gear was broken. Various studies have been made to determine the type and possible reasons of the damage.These are:_ studies carried out to determine the material of the shaft;_ studies carried out to determine the micro-structure;_ studies related to the fracture surface.There is a closer photograph of the fractured surfaces and fracture area in Fig. 4. The fracture wascaused by taking out circular mark gear seen in the middle of surfaces.Fig. 1. Schematic of the analysed differential.2. Experimental procedurepecimens extracted from the shaft were subjected to various tests including hardness tests and metallographic and scanning electron microscopy as well as the determination of chemical composition. All tests were carried out at room temperature.2.1. Chemical and metallurgical analysisChemical analysis of the fractured differential material was carried out using a spectrometer. The chemical composition of the material is given in Table 1. Chemical composition shows that the material is a low alloy carburising steel of the AISI 8620 type.Hardenability of this steel is very low because of low carbon proportion. Therefore, surface area becomes hard and highly enduring, and inner areas becomes tough by increasing carbon proportion on the surface area with cementation operation. This is the kind of steel which is generally used in mechanical parts subjected do torsion and bending. High resistance is obtained on the surface and high fatigue endurance value can be obtained with compressive residual stress by making the surface harder 57.In which alloy elements distribute themselves in carbon steels depends primarily on the compound- and carbide-forming tendencies of each element. Nickel dissolves in the a ferrite of the steel since it has less tendency to form carbides than iron. Silicon combines to a limited extent with the oxygen present in the steel to form nonmetallic inclusions but otherwise dissolves in the ferrite. Most of the manganese added to carbon steels dissolves in the ferrite. Chromium, which has a somewhat stronger carbide-forming tendency than iron, partitions between the ferrite and carbide phases. The distribution of chromium depends on the amount of carbon present and if other stronger carbide-forming elements such as titanium and columbium are absent. Tungsten and molybdenum combine with carbon to form carbides if there is sufficient carbon present and if other stronger carbide-forming elements such as titanium and columbium are absent. Manganeseand nickel lower the eutectoid temperature 8.Preliminary micro structural examination of the failed differential material is shown in Fig. 5. It can be seen that the material has a mixed structure in which some ferrite exist probably as a result of slow cooling and high Si content. High Si content in this type of steel improves the heat treatment susceptibility as well as an improvement of yield strength and maximum stress without any reduction of ductility 9. If the microstructure cannot be inverted to martensite by quenching, a reduction of fatigue limit is observed. There are areas with carbon phase in Fig. 5(a). There is the transition boundary of carburisation in Fig. 5(b) and (c) shows the matrix region without carburisation. As far as it is seen in these photographs, the piece was first carburised, then the quenching operation was done and than tempered. This situation can be understood from blind martensite plates.2.2. Hardness testsThe hardness measurements are carried out by a MetTest-HT type computer integrated hardness tester. The load is 1471 N. The medium hardness value of the interior regions is obtained as 43 HRC. Micro hardness measurements have been made to determine the chance of hardness values along the cross-section because of the hardening of surface area due to carburisation. The results of Vickers hardness measurement under a load of 4.903 N are illustrated in Table 2.2.3. Inspection of the fractureThe direct observations of the piece with fractured surfaces and SEM analyses are given in this chapter. The crack started because of a possible problem in the bottom of notch caused the shaft to be broken completely. The crack started on the outer part, after some time it continued beyond the centre and there was only a little part left. And this part was broken statically during sudden starting of the vehicle at the traffic lights. As a characteristic of the fatigue fracture, there are two regions in the fractured surface. These are a smooth surface created by crack propagation and a rough surface created by sudden fracture. These two regions can be seen clearly for the entire problem as in Fig. 4. The fatigue crack propagation region covers more than 80% of the cross-section.Shaft works under the effect of bending, torsion and axial forces which affect repeatedly depending on the usage place. There is a sharp fillet at level on the fractured section. For this reason, stress concentration factors of the area have been determined. Kt = 2.4 value (for bending and tension) and Kt = 1.9 value (for torsion) have been acquired according to calculations. These are quite high values for areas exposed to combined loading.These observations and analysis show that the piece was broken under the influence of torsion with low nominal stresses and medium stress concentration 10.The scanning electron microscopy shows that the fracture has taken place in a ductile manner (Fig. 6). There are some shear lips in the crack propagation region which is a glue of the plastic shear deformations. Fig. 7 shows the beach marks of the fatigue crack propagation. The distance between any two lines is nearly 133 nm.3. ConclusionsA failed differential pinion shaft is analysed in this study. The pinion shaft is produced from AISI 8620 low carbon carburising steel which had a carburising, quenching and tempering heat treatment process. Mechanical properties, micro structural properties, chemical compositions and fractographic analyses are carried out to determine the possible fracture reasons of the component. As a conclusion, the following statements can be drawn:_ The fracture has taken place at a region having a high stress concentration by a fatigue procedure undera combined bending, torsion and axial stresses having highly reversible nature._ The crack of the fracture is initiated probably at a material defect region at the critical location._ The fracture is taken place in a ductile manner._ Possible later failures may easily be prevented by reducing the stress concentration at the criticallocation.AcknowledgementThe author is very indebted to Prof. S. Tasgetiren for his advice and recommendations during the study.References1 Heisler H. Vehicle and engine technology. 2nd ed. London: SAE International; 1999.2 Makevet E, Roman I. Failure analysis of a final drive transmission in off-road vehicles. Eng Failure Anal 2002;9:57992.3 Orhan S, Akturk N. Determination of physical faults in gearbox through vibration analysis. J Fac Eng Arch Gazi University2003;18(3):97106.4 Tas_getiren S, Aslantas_ K, Ucun I. Effect of press-fitting pressure on the fatigue damages of root in spur gears. Technol Res: EJMT2004;2:219.5 Nanawarea GK, Pableb MJ. Failures of rear axle shafts of 575 DI tractors. Eng Failure Anal 2003;10:71924.6 Aslantas_ K, Tas_getiren S. A study of spur gear pitting formation and life prediction. Wear 2004;257:116775.7 Savas_ V, O zek C. Investigation of the distribution of temperature on a shaft with respect to the deflection. Technol Res: EJMT2005;1:338.8 Smith FW. Principles of materials science and engineering. 3rd ed. USA: McGraw-Hill Series; 1996. p. 51718.9 ASM metal handbook, vol. 1. Properties and selection, irons, steels, and high performance alloys; 1991.10 Voort GFV. Visual examination and light microscopy. ASM handbook metallography and microstructures. Materials Park(OH): ASM International; 1991. p. 10065.汽车差速器小齿轮轴的失效分析摘要差速器被用于减少的速度并且提供传输运动中的力矩。从发动机到轮子转动它根据适当的角度在车辆和提供内部和外部的车轮转是不同的。小齿轮啮合和轴在入口处是作为一个单独的部分而制造它们是在不同的形式根据车辆的类型。镜子齿轮将工作用这个前齿轮应该熟悉组装。如有任何故障,他们应该被改变成双。一般来说,在这些系统中有磨损的齿轮。齿轮检查这方面的研究以有一种轴断裂作为齿轮被破坏。在这项研究中,失效分析型差动齿轮轴被执行。材料力学特性获得第一。然后,材料的显微结构和化学成分已经决定了。一些显微研究学者进行疲劳断裂条件的分析关键词:差速器;断裂,动力装置,齿轮轴一 介绍对于整车的结构体系来说，差速器只是装在两个驱动半轴之间的一个小轴承。看似微不足道，但如果没有它，两个驱动半轴之间以刚性连接，左右车轮的转速保持一致，汽车将只能直线行驶，不能转弯。自从一百年前雷诺汽车公司的创始人路易斯雷诺发明出差速器后，它就在汽车上发挥着巨大作用。现在每辆汽车上都装有差速器。 顾名思义，差速器的作用就是使两侧车轮转速不同。当汽车转弯时，例如左转弯，弯心在左侧，在相同的时间内右侧车轮要比左侧车轮走过的轨迹要长，所以右侧车轮转的要更快一些。要达到这个效果，就得通过差速器来调节。差速器由差速器壳、行星齿轮、行星齿轮轴和半轴齿轮等机械零件组成。 发动机的动力经变速器从动轴进入差速器后，直接驱动差速器壳，再传递到行星齿轮，带动左、右半轴齿轮，进而驱动车轮，左右半轴的转速之和等于差速器壳转速的两倍。当汽车直线行驶时，行星齿轮，左、右半轴齿轮和驱动车轮三者转速相同。当转弯时，由于汽车受力情况发生变化，反馈在左右半轴上，进而破坏差速器原有的平衡，这时转速重新分配，导致内侧车轮转速减小，外侧车轮转速增加，重新达到平衡状态，同时，汽车完成转弯动作。以下简介两种差速器：一 开式差速器 切诺基的开式差速器的结构，是典型的行星齿轮组结构，只不过太阳轮和外齿圈的齿数是一样的。在这套行星齿轮组里，主动轮是行星架，被动轮是两个太阳轮。通过行星齿轮组的传动特性我们知道，如果行星架作为主动轴，两个太阳轮的转速和转动方向是不确定的，甚至两个太阳轮的转动方向是相反的。 车辆直行状态下，这种差速器的特性就是，给两个半轴传递的扭矩相同。在一个驱动轮悬空情况下，如果传动轴是匀速转动，有附着力的驱动轮是没有驱动力的，如果传动轴是加速转动，有附着力的驱动轮的驱动力等于悬空车轮的角加速度和转动惯量的乘积。 车辆转弯轮胎不打滑的状态下，差速器连接的两个半轴的扭矩方向是相反的，给车辆提供向前驱动力的，只有内侧的车轮，行星架和内侧的太阳轮之间由等速传动变成了减速传动，驾驶感觉就是弯道加速比直道加速更有力。 开式差速器的优点就是在铺装路面上转行行驶的效果最好。缺点就是在一个驱动轮丧失附着力的情况下，另外一个也没有驱动力。 开式差速器的适用范围是所有铺装路面行驶的车辆，前桥驱动和后桥驱动都可以安装。 二 限滑差速器 限滑差速器用于部分弥补开式差速器在越野路面的传动缺陷，它是在开式差速器的机构上加以改进，在差速器壳的边齿轮之间增加摩擦片，对应于行星齿轮组来讲，就是在行星架和太阳轮之间增加了摩擦片，增加太阳轮与行星架自由转动的阻力力矩。 限滑差速器提供的附加扭矩，与摩擦片传递的动力和两驱动轮的转速差有关。 在开式差速器结构上改进产生的LSD，不能做到100的限滑，因为限滑系数越高，车辆的转向特性越差。 LSD具备开式差速器的传动特性和机械结构。优点就是提供一定的限滑力矩，缺点是转向特性变差，摩擦片寿命有限。 LSD的适用范围是铺装路面和轻度越野路面。通常用于后驱车。前驱车一般不装，因为LSD会干涉转向，限滑系数越大，转向越困难。最后一级齿轮（也就是输出齿轮)可以直接或间接被变速箱齿轮驱动，当发动机和传动装置结合在一起形成便成为一个完整的结构时，采用直接驱动器驱动。间接驱动最终驱动器在车尾处的弹簧连接车身结构或者非悬挂并纳入后轴套管中。最后的驱动齿轮应用在传输系统中有下列原因：（1）从变速箱和传动轴驱动改变90度重新定向驱动（2）提供在发动机和驱动轮之间的永久的齿轮减速在车辆中，差速器是主要部分用于传送从发动机到车轮的运动。里面的的轮子转动的少,外面的轮子转动的多就没有侧向的滑移和猛冲。差速器通常被放置在后桥的中部,由小齿轮啮合,镜子齿轮,齿轮箱,两轴差和两个小三角齿轮组成。 图1为差速器的原理图，图二为断裂齿轮轴
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号