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毕 业 设 计 任 务 书1毕业设计课题的任务和要求：本课题要完成的任务本课题要求对零件进行深入的分析与研究，熟悉零件的结构特点，应用AutoCAD软件绘制零件图，对零件进行加工工艺分析，确定合理的加工方法和加工工艺，制定零件加工工艺规程，并设计非通用工序的工装，实现两道工序专用夹具的设计。解决在设计过程中所遇到的具体问题。本课题的要求对本课题进行深入的分析与研究，熟悉所用软件的的工作原理与工作过程。熟练掌握所使用设计方法的一般步骤，在此基础上对工艺知识和工装设计知识进行深入的探讨，设计出满足课题要求工艺规程和工装。2毕业设计课题的具体工作内容（包括原始数据、技术要求、工作要求等）：1）排气凸轮轴的原始数据、技术要求、工作过程；2）根据给定的零件，完成零件的工艺分析；3）做出所给零件的三维视图，利用软件具有的功能将三维图纸转换成二维的图纸，且要求尺寸标注、视图符合国家标准4）完成工艺规程及工装设计，并撰写出详细的工艺说明报告。毕 业 设 计 任 务 书3对毕业设计课题成果的要求包括毕业设计、图纸、实物样品等：1）开题报告一份；2）标准图纸幅面不少于A0两张（至少有一张装配图）；3）设计说明书一份，光盘一张；4）外文翻译资料一篇。4毕业设计课题工作进度计划：起 迄 日 期工 作 内 容2 月 29日3月21日3 月22 日 5月3日5 月4 日 5 月24日5 月25 日 6月2 日6 月3 日 6 月5日查阅相关资料、撰写开题报告。 把自己所查阅的资料进一步进行整理分析，学习需要掌握的软硬件知识。 完成本课题的主要设计，绘制图纸。 翻译外文资料，撰写说明书。 递交毕业设计，准备答辩。学生所在系审查意见： 系主任： 2016年 2月 29日Automotive engine camshaftBrief introductionThe camshaft is a part of the piston engine. Its role is to control the opening and closingoperation of the valve. Although the camshaft rotational speed in a four-stroke engine is a half ofthe crankshaft (the same as the camshaft rotational speed in a two-stroke engine with thecrankshaft), but usually it is still very high speed, but also need to withstand the large torque, sothe design right demanding camshaft in terms of strength and support material is generally aspecial cast iron, occasionally using forgings. Valve motion law related to engine power andoperation characteristics, the design in the design process of the engine camshaft occupies a veryimportant position.StructureThe main body of the camshaft is the same as the one with the cylinder length of thecylindrical rod. The above sets have several cam for driving the valve. One end of the camshaftcamshaft bearing support and the other end is connected to the drive wheels.Cam side was egg-shaped. The design aims to ensure the the cylinder sufficient air intake andexhaust, specifically, within the shortest possible time to complete the valve opening and closingmovements. In addition, taking into account the durability of the engine and the smoothness ofoperation, the valve can not be generated due to the deceleration process of opening and closingmovements too much too large the impact of serious wear and tear of the valve, otherwise it willcause an increase in noise or other serious consequences. Therefore, the cam and the power of theengine torque output as well as the operation of the ride there is a direct relationship.Generally inline engine, a cam corresponding to a valve V-type engine or horizontal opposedtype engine, every two valves share a cam. The rotary engine the valveless with gas enginebecause of its special structure, does not need to camPositionIn the long period of time, the bottom-mounted camshaft in an internal combustion engine ismost common. Typically such engines, the valve is located in the top of the engine camshaftmachine, i.e., so-called the OHV (Over Head Valve, OHV) engines. Usually camshaft located onthe side of the crankcase, through the gas distribution agencies (such as tappet, push rod, rocker,etc.) valve control. Bottom-mounted camshaft general also called side-mounted camshaft. Fardistance valve, and each cylinder is usually only two valves in such an engine camshaft, so thespeed is usually slower, ride comfort is poor, the output power is also relatively low. However, theengine output torque and low-speed performance of this structure is relatively good, relativelysimple structure and easy maintenance.Now most of the production cars engine is equipped with overhead camshaft. The overheadcamshafts structure closer to the camshaft valve, to reduce the kinetic energy of the waste causedby the bottom-mounted camshaft due to the larger distance between the camshaft and the valveshuttle. Overhead camshaft of the engine valve opening and closing action is relatively rapid, andhence higher speed, and the smooth running is also better. The engine of the the overheadcamshafts structure appeared earlier the SOHC (Single Over Head Cam, overhead single camshaft)engine. This engine is only installed at the top of a camshaft, and therefore generally only two tothree valves of each cylinder (the intake air a to two exhaust), the high-speed performance hasbeen limited. Technology updates DOHC (Double Over Head Cam, double overhead camshaft)engine, this engine with a two camshafts per cylinder can be installed four to five valves (intaketwo to three, Pai gas two), high-speed performance significantly improved, but at the same timethe low-speed performance will be affected to some degree, the structure will be complicated anddifficult to repair.ClassificationAccording to the the camshaft number of how many, can be divided into single overheadcamshaft (SOHC) and double overhead camshaft (DOHC), two kinds. The single overheadcamshaft camshaft is only one camshaft, double overhead camshaft is two, this is toostraightforward explanation.The single overhead camshaft with a camshaft in the cylinder head, direct drive into theexhaust valve, it has a simple structure, suitable for high-speed engine. Generally used in the pastside camshaft, the camshaft in the cylinder side, is driven directly by a timing gear. The valvelifter to the rotation of the camshaft is converted into reciprocating motion of the valve must beused to transfer power. Thus, more parts of the reciprocating motion, the inertial mass, is notconducive to high-speed movement of the engine. Moreover, the slender tappet has a certaindegree of flexibility, prone to vibration, accelerated component wear, even the valve control islost.DOHC cylinder head equipped with two camshafts, one is used to drive the intake valve, theother for driving the exhaust valve. Double overhead camshaft camshaft and valve spring designless demanding, especially for the hemispherical combustion chamber of the valve V-shapedconfiguration, but also facilitate and used in conjunction with four-valve gas distribution agencies.FaultCamshaft common faults including abnormal wear and tear, abnormal wear of the symptomsoften first appear before the occurrence of abnormal sound as well as fracture, abnormal soundand fracture.(1) Camshaft almost at the end of the engine lubrication system, lubrication situation is notoptimistic. If the oil pump is too long and so insufficient oil pressure or the lubricants Roadblockage caused by lubricating oil can not reach the camshaft bearing cap fastening boltstightening torque caused by excessive oil can not enter the the camshaft gap will causing abnormalwear of the camshaft.(2) the abnormal wear of the camshaft causes the gap increases between the camshaft bearing,the camshaft movement occurs when the axial displacement, resulting in abnormal noise.Abnormal wear will lead to increased gap between the drive cam with hydraulic tappets, camcombined with hydraulic tappets will collide, resulting in abnormal noise.(3) camshaft sometimes fracture and other serious fault, common causes of hydraulic tappetcracked or severely worn, serious poor lubrication the camshaft poor quality and camshaft timinggear rupture.(4) In some cases, the failure of the camshaft is man-made causes, in particular themaintenance of the engine camshaft not correct disassembly. Such as demolition of the camshaftbearing caps with a hammer strength knocking or prying with a screwdriver, or install the bearingcap installed the wrong position does not match the result in the bearing cap and bearing, orbearing cover the fastening bolt tightening torque is too large. Install bearing cap should payattention to the direction of the arrow and the position number marked on the surface of thebearing cap, and in strict accordance with the provisions of torque using the torque wrench tightenthe bearing cap fastening bolts.RefitIn order to enhance the power of the engine, some converted stores a modified camshaftengine face lift high angle camshaft (Hi-camshaft CAM) is a common form of modified method.This modification operation is not complicated, but because of the lack of understanding of somemodification cam on the camshaft angle and works so that the modified effect is not obvious evenlead to the deterioration of the performance of the engine.High angle camshaft relative to ordinary camshaft cam angle of about 240, high anglecamshaft cam angle can often reach over 280. The large angle of the camshaft can extend thevalve open time, increase the valve lift, the intake valve and the exhaust valve open as early andlate off, so that more air into the cylinder, in order to improve the engine, the power of the highspeed output. Should choose for civilian vehicles, modified cam camshaft angle 278, will be asignificant increase in working an angle greater than 278camshaft valve overlap angle, so thatthe power of the engine high speed improve a lot, but engine cylinder seal is not good at low speedand cause the idling serious jitter or even turn off, so that the vehicle can not adapt to everyday use,and can only be used for competition purposes.Production technologyThe camshaft is one of the key parts of the engine, the hardness of the camshaft peach apicaland white layer depth is to determine the key technical indicators camshaft life and engineefficiency. , Should be considered to ensure that the cam has a sufficiently high hardness and afairly deep white layer premise journal does not appear high carbide, so that it has a better cuttingperformance.Currently, the main method of domestic and foreign production camshaft: steel forging blankby cutting the cam peach tip martensitic layer formed some of the high-frequency quenchingprocess. The end of the 1970s, Germany and France have developed a new camshaft argon arcremelting process; hardened cast iron camshaft otherwise dominated by the United States; chilledcast iron camshaft mainly to Japan and France; well cam parts of the Cr-Mn-Mo alloy coatingscasting surface alloying production. 毕 业 设 计 开 题 报 告1结合毕业设计情况，根据所查阅的文献资料，撰写2000字左右的文献综述： 文 献 综 述 凸轮轴是汽车发动机配气机构中重要的零件，凸轮轴的结构设计与加工质量好坏，直接影响着发动机的性能。近年来，因环境保护的需要，正在开发低油耗、低污染的发动机。为了解决汽车尾气无污染排放问题，实现发动机的高转速、高输出功率，许多发动机采用多气门及配气相位、气门升程可变的结构，这就增加了气门弹簧的载荷。同时，为了降低油耗及摩擦损耗，凸轮与摇臂间采用滚子结构，凸轮与滚子的接触面形成高压力区，这对凸轮轴运动的平稳性、动平衡、耐磨性能及抗扭强度提出了更高的要求。另外，为了达到汽车轻型化、低成本的目的，在不影响各个零件性能要求的前提下，应该使零件尽可能简化加工、降低重量，材料使用也更趋合理。凸轮轴的构造 凸轮轴的主体是一根与气缸组长度相同的圆柱形棒体。上面套有若干个凸轮，另一端与驱动轮相连接。 凸轮的侧面呈鸡蛋形。其设计的目的在于保证气缸充分的进气和排气，尽可能在短时间内完成气门的开、闭动作。另外考虑到发动机的耐久性和运转的平顺性，气门也不能因开闭动作中的减速过程产生过多过大的冲击，否则就会造成气门的严重磨损、噪声增加或者其它严重后果。因此，凸轮和发动机的功率、扭矩输出以及运转的平顺性有很直接的关系。 一般来说，直列式发动机中，一个凸轮就对应一个气门。V型发动机或水平对置式发动机则是每两个气门共享一个凸轮。而转子发动机和无阀配气发动机由于其特殊的结构，并不需要凸轮。为了实现轻量化，易于加工且低成本，以及发动机的高转速、高输出功率，发动机部件，尤其是凸轮轴的设计必须重新考虑，要求其结构紧凑、功能高度集中、重量轻，能承受更高的接触压力。在目前的凸轮轴应用中，已经将缸盖润滑系统集中于中空式凸轮轴，将实现缸内直喷的燃油泵驱动组件在凸轮轴上实现，将VVT(可变正时气门)在凸轮轴尾端使用。在配气机构中，对凸轮轴各个部位的性能要求是不同的。对于凸轮和燃油泵驱动轮，要求耐磨损、耐胶着、耐点蚀；对于轴颈要求滑动性能好；对于轴则要求刚性、弯曲、扭转性能好1-2。凸轮轴的国内外发展趋势 金属、塑料复合凸轮轴已在美国应用。将粉末金属成型并经磨削加工的凸轮片和中空钢轴放入模具内,在中空轴周围注射塑料。凸轮片和轴之间不再有金属直接接触,而是由塑料固定形成一体。这种凸轮轴的成本及重量均可减少40%,可降低发动机噪声,加工准备时间由原来的几小时缩短至几分钟。 装配式凸轮轴目前以较快的速度发展,主要应用于高性能发动机上。目前,世界上许多汽车工业发达的汽车制造厂正在越来越多使用装配式凸轮轴制造新技术,但因技术掌握的程度、方法不同,使用装配式凸轮轴的种类也不同。日本日野自动车工业株式会社在20世纪90年代初开发了热套和焊接组合的生产方式,凸轮采用碳钢,用冷精锻方法制造,轴颈采用高频淬火钢管制成,轴则采用冷拔碳钢管。日本丰田汽车公司也有相似的生产方式。日本精工株式会社用扩管法生产凸轮轴,产品的刚度较铸造产品提高1.7倍,累计生产已达300万根。日本柱塞环株式会社从20世纪80年代中期开始生产烧结连接式凸轮轴,1992年开始生产专门用于低能耗发动机的凸轮轴,凸轮采用烧结合金,具有非常好的耐磨损及耐点蚀性能。目前已生产了750万根。从20世纪90年代中期该公司开始研制刮削连接式凸轮轴。美国MTS2SA公司、TORINGTON公司、FEDERAL2MDOGUL公司、通用汽车公司、福特汽车公司都已将装配式凸轮轴应用于生产之中。德国的大众汽车公司、奔驰汽车公司、THYSSENK2RUPP公司,英国的T&NTechnology公司、GKNBoundBrook公司也都先后开发研制了装配式凸轮轴的生产工艺及设备。目前在我国仅上海大众汽车公司有1条生产装配式凸轮轴的生产线,其他企业还处于空白阶段。个别单位曾经研制了烧结连接式凸轮轴,但都没有实用化。吉林大学对装配式凸轮轴已经研制开发了多年,重点针对滚花连接方式进行了研究,对连接机理进行了探讨,应用计算机模拟方法对连接部位工作状态的应力应变做了模拟研究,并对装配力做了不同情况的试验分析。在连接试验的基础上开发了自动化装配机。装配式凸轮轴已发展二十多年,除了上述的方法外,正大力开发应用复合材料,例如陶瓷材料等制造凸轮轴。随着装配式凸轮轴生产技术的提高,性能更好、成本更低、技术多样化的装配式凸轮轴将会涌现出来3。 1981年7月,日本丰田汽车公司宣布,世界第1个粉末冶金技术制成粉末烧结结中空整体凸轮轴,已大量用于IS型直列式死缸发动机,粉末烧结整体中空凸轮轴是由8个凸轮片、5个轴颈、1个齿轮、2个燃料泵凸轮、1个前轴颈、1根钢管18个零件组合烧结而成。粉末烧结整体中空凸轮轴的制造工艺是:将与烧结和模锻的粉末凸轮片、齿轮、轴颈嵌入或压入钢管轴上,然后对粉末凸轮进行正式烧结(1100e、30min,分解氨)。同时以纯铜为钎料,将轴颈、齿轮钎焊在钢管轴上。烧结时,粉末合金中的Fe-P-C组分生成液相,使凸轮片生产收缩和扩张粘结于钢管轴表面。矫直,检验后,经精加工,即制成烧结中空整体凸轮轴。烧结中空整体凸轮轴与铸铁凸轮轴相比的技术经济指标效果:1)质量减轻了26%。2)实际发动机的电动回转试验表明,烧结合金凸轮轴的磨损仅为原用冷铸铁的1/7。3)烧结合金凸轮轴的外形接近最终形状,磨削加工量小,因此,凸轮轴磨床可减少20%,不需要钻油路。4)钢管轴内孔可用作发动机油的主通路。发动机油通过凸轮内孔,由汽缸组供给凸轮、轴颈、燃料泵凸轮及驱动齿轮的分配器,并通过轴颈将油供给余隙调节器。因此,不再需要输油管,润滑系统可大大简化。凸轮轴的机械加工量可大大减4。 日本精工株式会社采用内高压轴管扩径连接,生产的凸轮轴累计已达300万根,产品的刚度较铸造凸轮轴提高1.7倍。日本丰田汽车公司也有相似的生产方式。上海通用汽车公司采用耐磨烧结铁基合金材料凸轮与空心轴体通过机械扩径来实现联接,用于轿车中空装配式凸轮轴生产。德国蒂森克虏伯普里斯坦公司采用轴向滚花连接方式,以1200万根中空装配式凸轮轴的年产量成为全球市场的领导者。在国内,吉林大学对滚花连接技术进行了深入研究,并开发了中空装配式凸轮轴新型滚花连接技术与三轴CNC装配机(专利技术)。在汽车领域,中空装配式凸轮轴新技术已在高性能的发动机上得到应用。美国福特汽车公司的GT)90汽油机(V型12缸)顶置式凸轮轴,通用汽车的LN2汽油机(直列4缸)顶置式凸轮轴和3100SFI汽油机(V型6缸)顶置凸轮轴,日本日野公司的J08C系列柴油机(直列4缸和6缸)顶置式凸轮轴,上海通用汽车公司的别克发动机顶置式凸轮轴,均采用中空装配式凸轮轴5。 国内外生产凸轮轴的材质很多,有45钢、球墨铸铁、合金铸铁。目前,常使用的铸造方法是壳型铸造,其中包括铁型覆砂6-7和壳型填铁丸两种铸造工艺,其他还有如消失模铸造等。壳型铸造是20世纪40年代由德国约翰尼斯克朗宁(Johanes2Corning)发明的,亦称为克朗宁法8-10,壳型铸造生产的铸件具有表面粗糙度低,尺寸精度高等优点,能够满足冷铁多,形状复杂的零件的铸造,适用于凸轮轴、曲轴等轴类零件的生产,在世界上属先进工艺,具有很广阔的应用前景。 清华大学李双寿等人研究了球铁凸轮轴的激光表面处理11,发现经过该技术处理之后,球铁凸轮轴的表层由外而内分别是熔凝层、淬硬层和基体,并且其硬度均大于58HRC,搭接处的硬度也没有降低。AstashkevichBM等人研究了激光表面处理在所有的铸铁、中碳钢以及工具钢中的应用,指出材料的淬透性和硬度等都受到激光处理的一些可变参数的限制,比如能量大小、光束直径、光束形状、扫描速度以及聚焦条件等的限制12-13。在国外,ChernyshevAN等人14，通过试验研究发现灰铸铁和具有球状石墨的高强铸铁不适合于使用重熔工艺来进行表面强化,其原因有3点:1)产量大幅度降低;2)熔池内的碳没有完全分解,耐磨性降低;3)钨电极消耗太大。他们指出用蠕墨铸铁来代替灰铸铁和具有球状石墨的高强铸铁效果更好,还指出参数的变化会影响激冷层中片状渗碳体的分布。2005年英国哥伦比亚大学AMitchell教授又将以前只是应用于精炼的电渣冶炼重熔法和真空电弧重熔法成功应用于工业纯铁生产的凝固控制阶段15.参考文献：1邢铭.凸轮轴的发展趋势J.汽车与配件，2013（15）：36-37.2郝军清.新材料新工艺在凸轮轴生产中的应用J.内燃机与动力装,2006,6.3杨慎华.装配式凸轮轴制造技术现状与发展趋势J.内燃机工程,2004,25(2).4乔健.中空装配式凸轮轴连接技术及应用J.车用发动机,2007,31(1):4.5黄列群,潘东杰.铁型覆砂铸造及其发展J.现代铸铁,2006(3):12-18.6李晓东.数值模拟在铁型覆砂铸造中的应用J.汽车工艺与工料,2002(8):69-71.7Le Serve FL.ShellMouldingMaint ains Status as Leading Precision Sandcasting TechniqueJ.Foundry Trade Journal,1981(11):707-715.8李平,蔡启舟,魏伯康.壳型铸造技术在高品质凸轮轴上的应用研究J.铸造工程,2003(4):1-4.9李平,魏伯康,段汉桥,等.壳型铸造技术在高品质凸轮轴上的应用研究J.铸造工程,2003(4):1-4.10李双寿,陆劲昆,边庆月,等.球墨铸铁凸轮轴的激光表面熔凝处理J.金属热处理,2005,30(2):4-8.11 Astashkevich BM , Zinovev GS , Voronin IN . Restoring dieselengine camshafts by laser treatmentJ . Metal Scienceand Heat Treatment , 1996,38(11-12):512-514.12Senthil Selvan J , Subramanian K , Nath AK . Effect of laser surfacehar deningonEn18 (AISI5135) steelJ . Journa lofM at erials . Processing Technology , 1999,91:29-36.13刘佑平.提高内燃机凸轮轴耐磨性的工艺方法.14Chernyshev AN , Kaplina IN , Serapin MI . Surface hardening with remelting of functional surfaces of cast iron camshafts J. MetalScience and Heat treatment,1996,38(9210):440-442.15Mitchell A. Solidification i nremeltingprocesses J. Materials Science and Engineering A,2005,413-414,10-18. 毕 业 设 计 开 题 报 告本课题要研究或解决的问题和拟采用的研究手段（途径）： 排气凸轮轴零件设计的任务是让我们综合运用我们所学的机械设计基础、数控编程、CAD技术、机械制图、机械制造原理、机械加工、机械制造工艺等知识，来完成凸轮轴零件的三维造型设计、凸轮轴零件工艺规程文件编制、相关数控程序编制和相关夹具的设计。通过这一环境的训练，使我不但更加深入了解毕业设计的基本理论、基本知识、而且学会使用这些理论、基本知识去了解解决工程中的问题。 这次毕业设计的目的就是要对机械零件的加工设计制造过程有所了解，也是为了巩固所学的关于机械设计加工的理论知识,培养分析和解决问题的能力,提高自己的设计能力和创新设计能力。凸轮轴凸轮轴的零件分析 在选择各表面、孔及槽的加工方法时，要考虑加工表面的精度和表面粗糙度要求，根据各加工表面的技术要求，选择加工方法及分几次加工；要根据生产类型选择设备，在大批量生产中可采用高效率的设备。在单件小批量生产中则常用通用设备和一般的加工方法。如、柴油机连杆小头孔的加工，在小批量生产时，采用钻、扩、铰加工方法；而在大批量生产时采用拉削加工；要考虑被加工材料的性质，例如：淬火钢必须采用磨削或电加工；而有色金属由于磨削时容易堵塞砂轮，一般都采用精细车削，高速精铣等；要考虑工厂或车间的实际情况，同时也应考虑不断改进现有加工方法和设备，推广新技术，提高工艺水平；此外，还要考虑一些其它因素，如加工表面物理机械性能的特殊要求，工件形状和重量等。凸轮轴的技术要求1） 支承轴颈的尺寸精度及各支承轴颈间的同轴度。2）止推面对于支承轴线的垂直度。3）凸轮轴基面的尺寸精度和相对于支承轴颈的轴线的同轴度。4）凸轮的位置精度。5）凸轮的形状精度。凸轮轴的重要加工工艺1.中心孔的加工加工中心孔的刀具一般都采用标准中心钻(特殊中心孔区别对待),工艺安排上分2次进行:热处理之前和热处理之后。此道工序的关键是控制好60b的定位锥面的公差(?15c?20c),且需用专用工具(模拟后续机床的定位顶针)进行全数检查,以控制凸轮轴的轴向开档精度(要求?0.2?0.5mm),防止凸轮铣时出现未铣出的毛边。2.热处理 感应淬火时应根据不同的工件材质。在满足硬度要求的前提下找出淬火的边界条件,控