拖拉机驱动轴工艺路线及热处理方案设计

1、攀枝花学院Panzhihua University本科毕业设计（论文）文献综述院 （系）： 材料工程学院2010级 专 业： 材料成型及控制工程 班 级： 铸造班 学生姓名： 夏宇恒 学 号: 200911101040 2013 年 11 月 17 日本科生毕业设计（论文）文献综述评价表毕业设计（论文）题目拖拉机驱动轴工艺路线及热处理方案设计综述名称关于拖拉机驱动轴工艺路线及热处理方案设计的研究进展评阅教师姓名孙青竹职称讲师评 价 项 目优良合格不合格综述结构01文献综述结构完整、符合格式规范综述内容02能准确如实地阐述参考文献作者的论点和实验结果03文字通顺、精练、可读性和实用性强04反映题

2、目所在知识领域内的新动态、新趋势、新水平、新原理、新技术等参考文献05中、英文参考文献的类型和数量符合规定要求，格式符合规范06围绕所选毕业设计（论文）题目搜集文献成绩综合评语： 评阅教师（签字）： 年 月 日文献综述：关于拖拉机驱动轴工艺路线及热处理方案设计的研究进展1  驱动轴简介 驱动轴是装载机工作装置的一种，是一种可以推进装载机光滑度，使得所述驱动轮可按照不同的角速度转动的装置，通过花键及锥度部分紧配合将扭矩由行星架传到后轮上的装置。拖拉机驱动轴是拖拉机驱动后轮转动、传递力矩的关键零件 ，在工作中处在低速大转矩工况 ，受到扭转和弯曲复合载荷的作用 ，失效损坏的形式一

3、般为疲劳损坏。其扭转疲劳强度对驱动轴的破坏影响较大 。由于驱动轴同时受扭转和弯曲载荷 ，并伴有冲击性载荷和复合应力的作用 ，对驱动轴要求有较好的综合力学性能硬度高的扭转疲 劳强 度、一定的韧性 以及花键和轴颈表面有高和高的耐磨性 。所以目前用作拖拉机驱动轴的材料一般是合金中碳结构钢 ，经下料一锻压一粗 车一调质一机加工后 ，在花键及轴颈等处表面感应淬火处理，最后磨削、探伤得到驱动轴成品。如果零件结构与锻压合理 ，热处理控制得当，通常可以满足零件对疲劳强度的要求。但在实际应用中，拖拉机驱动轴断裂现象时有发生 ，除零件结构 、锻压等 因素外 ，热处理控制不 当，特别是淬硬层不连续也会直接影响驱动轴

4、的疲劳强度与静扭强度。我们对淬硬层不连续对静扭强度 的影响以及提高驱动轴的静扭强度做了初步探索。2 驱动轴的工作条件、性能要求、材料 （1）工作条件 ：驱动轴受、扭转、剪切、拉压、冲击等交变应力，还可造成驱动轴的扭转和弯曲振动，产生附加应力；应力分布不均匀；驱动轴颈与轴承有滑动摩擦。 （2）性能要求 ： 驱动轴的失效形式主要是疲劳断裂和轴颈严重磨损。因此材料要有高强度、一定的冲击韧性、足够弯曲、扭转疲劳强度和刚度，轴颈表面有高硬度和耐磨性。 （3）驱动轴材料 ：锻钢驱动轴：优质中碳钢和中碳合金钢，如40、45、35Mn2、40Cr, 45Cr、35CrMo钢等。3 改进措施驱动轴是许多机器中重

5、要的驱动部件之一，其工作特性要求材料的综合力学性能较高。而化学成分不符合技术要求、应力集中、热处理工艺不当等是轴产生断裂的常见原因。这些原因的在制造过程中或由于设计不当造成的。因此，在制造过程中应严格控制热处理和机加工在内的每一个环节，并合理设计轴的结构。3.1驱动轴结构优化驱动轴依靠花键和锥度轴与行星架配合传递扭矩，锥度配合往往由于偏心螺栓松动和磨损，起不到传递扭矩的作用，因此，需要对驱动轴结构进行改进。去掉驱动轴锥度部分，并将驱动接盘与花键轴设计成两个独立零件，接盘设计成与驱动轴花键相配合的内花键槽，驱动轴花键设计成通体花键来传递扭矩，这样，扭矩完全由花键轴和行星架配合传递，花键轴上不会再

6、因与锥度轴过度出的变截面和强度不均匀产生应力集中现象，从而提高可驱动轴的强度。3.2热处理工艺优化齿根断裂是由于齿轮旋转过程中反复加载，在齿根去危险断面位置产生应力集中，当弯曲应力超过材料的弯曲疲劳极限时就可能发生齿轮的疲劳折断。为防止吃困的疲劳折断，除了适当的提高除轮的硬化层的硬度、强化轮齿表面、保持合理的硬化层深度，在吃廓硬化区形成有利的残余应力以外，齿廓硬化层分布的形状对断齿有重要的影响。花键采用高频加热淬火，表面硬度很高（5759HRC），但硬化层较浅，零件的整体强度不高。为此，在驱动轴结构优化后，将通体花键轴和驱动轴接盘的内花键进行中频淬火，零件的淬硬层可达28mm，提高疲劳强度。从

7、室内扭转疲劳实验结果来看，采用中频淬火的花键轴在超负荷条件下的有限寿命提高了几十倍。 4.热处理工序位置及热处理工艺选择： 热处理是机械制造过程中的重要工序。驱动轴的热处理工序位置及热处理工艺选择、安排是否得当，对于零件的质量及切削加工性能起着至关重要的作用。根据热处理的目的及工序位置不同，热处理分为预备热处理和最终热处理。4.1预备热处理的工序位置及热处理工艺选择： 为消除经过锻造的驱动轴的内应力、细化晶粒、均匀组织，并改善切削加工性能，为淬火作好组织准备，一般在锻造之后、切削加工之前，可采用退火或正火作为预备热处理。由于驱动轴尺寸较小，且厚度较均匀，在正火、退

8、火均可使用的前提下，为提高工作效率，宜选用正火作为预备热处理。 4.2 最终热处理的工序位置： 最终热处理包括各种淬火、回火、表面热处理等。零件最终热处理之后，即可获得所需的力学性能：因零件硬度较高，除磨削加工之外不宜进行其他形式的切削加工，故最终热处理均安排在半精加工之后，磨削加工之前。 4.3最终热处理工艺方法选择： 根据驱动轴的工作条件及失效形式，对驱动轴的技术条件要求如下： 根据以上技术条件，驱动轴材料 ：45Cr 采用的最终热处理工艺为：先调质，使表面保持较高的强度和冲击韧性；之后表面淬火，使轴表面硬度达

9、到高硬度要求，心部仍维持较低的硬度 。 5 热处理工艺 45Cr是合金调质钢中最常用的钢种，下面以45Cr制造的拖拉机的驱动轴说明其热处理工艺方法的选定和工艺路线的安排。驱动轴是发动机中一个重要的连接零件，在工作时它承受冲击性 的、周期变化的拉应力和装配时的预应力，要求它具有足够的强度、冲击韧性和抗疲劳性能。根据技术要求，其工艺路线及热处理方案可能有以下几种。 方案1：驱动轴的生产工艺路线如下 ：下料锻造退火（或正火）机加工（粗加工）调质机加工（精加工）直径90圆柱面与花键两处高频淬火检验装配。 该方案的优点：工艺简单，特别

10、是调质工艺，因为调质后再进行机械加工，无需考虑脱碳问题。 该方案的缺点是：加工余量大，特别是原材料浪费，调质效果不好。该种钢油淬火时临界直径约为2530mm,今传递扭矩危险断面处毛柸直径大于55mm,根据该种钢的端淬曲线可以推知，即使在表面也得不到半马氏体区，实际上只能得到网状铁素体及细片状珠光体组织。花键与锥度交界处恰好是花键高频淬火 过渡区，此处的强度比未经表面淬火的还差，而又是应力集中的危险断面。 方案2：下料荒车及钻直径23孔（应留加工余量，以备扩孔成直径23）机加工（粗加工）调质机加工成型直径90圆柱面、锥度及花键部分高频淬火检验装配。 该方案

11、的优点：克服了第一方案的调质效果不良，以及锥度与花键交界危险断面处的弱点，其使用性能将比第一方案大为改善。 该方案的缺点是：加工余量大，特别是原材料浪费，加工工序和工序间周转长，成本高。 方案3：法兰盘：下料锻造机加工（粗加工）调质机加工成形（花键只加工内孔，键槽未拉）直径90圆柱面外圆高频淬火拉削花键孔检验。花键轴：棒料钻孔料调质机加工成形花键中频淬火 该方案的优点：省料，在大量生产中花键可向钢厂订购管材；调质效果好，基本上与该种钢的临界直径相适应；感应加热淬火工艺单一，操作方便、质量稳定，因为直径90外圆高频淬火的目的是提高耐磨性，其与法兰盘连接处直径大，应力

12、小，故强度足够。 该方案的缺点：增加了法兰盘拉削内花键孔的工艺，但省去了锻造拔制锥度及花键部分直径的工序，简化了花键轴的加工。 所以采用第三种方案，制造陈本提高不多，而寿命大幅度提高，总的经济效果是良好的。 退火（或正火）作为预先热处理，是为了改善锻造组织，细化晶粒，有利于切削加工，并为随后的调质热处理做好组织准备。 调质热处理淬火：加热温度840±10，油冷，获得马氏体组织； 回火：加热温度525±25，水冷（防止第二类回火脆性）。 经过调质处理后金相组织应为回火索氏体，不允许有块状铁素体出现，否则会降低强度和韧

13、性。 6. This paper presents design method and vibrational analysis of composite propeller shafts. A propeller shaft is not limited to vehicles, but in many transmission applications can be used, but in this paper, the aim is to replace a metallic drive shaft by a two-piece composite drive shaft.

14、Designing of a composite drive shaft is divided in two main sections: design of the composite shaft and design of couplings. In composite shaft design some parameters such as critical speed, static torque and adhesive joints are studied; the behavior of materials is considered nonlinear isotropic fo

15、r adhesive, linear isotropic for metal and orthotropic for composite shaft. Along with the design all the analyses are performed using finite element software (ANSYS). The results show significant points about o . ptimum design of composite drive shafts.  7. Highlights The cause of the drive sh

16、aft fracture of the BWE SchRs630/6x25 was examined. The shaft fracture did not occur due to any errors in the material. The cause of the initial crack is inadequate machining of the shaft. The cause of the shaft fracture is the badly performed repair welding process. Abstract Drive in most bucket wh

17、eel excavators (BWEs) is accomplished through its electric motor, cardan shaft and planetary gearbox. In the BWE SchRs630/6x25, the planetary gearbox is cantilevered at the end of the hollow shaft which transmits the torque through the sprocket to the caterpillar track chain. In this BWE, the drive

18、shaft fracture occurs at the point of support on the penetration side. Experimental testing of the chemical composition and mechanical properties of the mat . erial of the shaft and metallographic inspections of the fracture surface by means of electronic and light microscopes carried out in the fir

19、st part of the paper have shown that there are no significant inhomogeneities and errors in the material of the shaft and that they do not cause damage. Further, the analysis of results referring to the mechanical properties and chemical composition of the repaired shaft at the point of welding, and

20、 particularly in the transition zone, shows that they considerably deviate from those prescribed for the material used. Significant inhomogeneity of the material, occurrence of cracks as well as the difference in the microstructure appear in this zone, which is the cause of shaft damage. The second

21、part of the paper presents the FEM analysis of effects of the cantilever type of support of the planetary gearbox and stress concentration at the point of support due to inadequate finishing, which caused the occurrence of an initial crack. The user unsuccessfully tried to eliminate this weakness by

22、 repair welding of the shaft.  8.Abstract In this research the torsional stability of a composite drive shaft torsion is studied. Composite materials are considered as the suitable choice for manufacturing long drive shafts. The applications of this kind of drive shafts are developed in various

23、 products such as cars, helicopters, cooling towers, etc. From the design point of view, local and global torsional instability of drive shafts limits the capability for them to transfer torque. After reviewing the closed form solution methods to calculate the buckling torque of composite drive shaf

24、ts, a finite element analysis is performed to study their behavior. Furthermore, to evaluate the results obtained by the finite element method, a comparison with experimental and analytical results is presented. A case study of the effect . s of boundary conditions, fiber orientation and stacking se

25、quence on the mechanical behavior of composite drive shafts is also performed. Finally, the reduction of the torsional natural frequency of a composite drive shaft due to an increase of applied torque is studied.   9. Abstract In this paper, a passive approach to reduce transmitted vibration ge

26、nerated by gear mesh contact dynamics is presented. The approach utilizes the property of periodic structural components that creates stop band and pass band regions in the frequency spectra. The stop band regions can be tailored to correspond to regions of the frequency spectra that contain harmoni

27、cs and sub-harmonics of the gear mesh frequency, attenuating the response in those regions. A periodic structural component is comprised of a repeating array of cells, which are themselves an assembly of elements. The elements may have differing material properties as well as geometric variations. F

28、or the purpose of this research, only geometric variations are considered and each cell is assumed to be identical. A perio . dic shaft is designed and machined in order to reduce transmitted vibration of a pair of spur gears. Analytical and experimental results indicate that transmitted vibrations

29、from gear mesh contact to the bearing supports are reduced at a variety of operational speeds under static torque preload.  10. One part of the work of composite engineers is to find cost effective uses for new fibre composites. One such use identified for carbon fibre is in the automotive prop

30、eller shaft. This is the fore and aft shaft transmitting the engine torque of a car or truck to the driven axle to propel the vehicle. This paper will relate the requirements for drive shafts to the properties of carbon fibres. Both technical and marketing requirements will be considered. The carbon

31、 fibre properties are related to performance when incorporated in a resin matrix. Reference will be made to work on alloying' carbon fibre with glass fibre. This is shown to enhance the overall cost effectiveness of the resulting parts. A final section will illustrate the important aspect of producing test data that build up the a . utomotive designer's confidence in the application of an unfamiliar material.参考文献：1机械工程检测技术（第三版）.高等教育出版社.2000年.主编：陈瑞阳，毛智勇. 2金属工艺学.北京机械工业出版社.2001年.主编：丁德全. 3金属热处理工艺学.哈尔滨工业大学出版社.2008.主编：夏立