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毕业设计（论文）任务书I、毕业设计(论文)题目：差速器主外壳机械加工工艺工装设计II、毕 业设计(论文)使用的原始资料(数据)及设计技术要求： 已知某差速器主外壳零件图，要求：1编制其批量生产的机械加工工艺规程：对零件图进行工艺分析，绘制二维及三维零件图（在UG NX 和AUTOCAD上），编制机械加工工艺过程卡片、机床加工工序卡2设计镗孔夹具：绘制二维及三维装配图。III、毕 业设计(论文)工作内容及完成时间：1. 搜集有关资料，熟悉零件结构及功用，撰写开题报告 第1周2. 相关外文文献资料的阅读与翻译（6000字符以上） 第2周3. 零件工艺路线设计 第3周第5周4. 机床加工工序设计 第6周第9周5. 镗孔夹具设计 第10周第13周 4周6. 撰写毕业论文 第14周第16周7. 答辩准备及毕业答辩 第17周 、主 要参考资料：1 王先逵. 机械制造工艺学.北京:机械工业出版社，20082 于骏一. 典型零件制造工艺.北京:机械工业出版社，19893 王凡. 实用机械制造工艺设计手册.北京:机械工业出版社，20084王启平. 机床夹具设计.哈尔滨：哈尔滨工业大学出版社，19965 张进生，房晓东主编. 机械工程专业课程设计指导.北京:机械工业出版社，20046 Yiming (Kevin) Rong. Samuel H. Huang, Zhikun Hou. Advanced Computer-aided Fixture Design.Elsevier Academic Press, 20057 曹岩，白瑀主编 机床夹具手册与三维图库 UGNX版.北京：化学工业出版社,2010 航空与机械工程系 机械设计制造及其自动化 专业 0781052 班学生（签名）： 填写日期： 2011 年 03 月 1 日指导教师（签名）： 助理指导教师(并指出所负责的部分)：机械设计制造及其自动化 系 主任（签名）： 附注:任务书应该附在已完成的毕业设计说明书首页。毕业设计（论文）外文翻译题目 钛合金攻螺纹技术及丝锥改进专 业 名 称 机械设计制造及其自动化班 级 学 号 078105235学 生 姓 名 曾 威指 导 教 师 王细洋填 表 日 期 2011 年 3 月 12 日 钛合金攻螺纹技术及丝锥改进【摘要】钛合金是一种比重小、强度高、耐腐蚀和耐热等特性的金属结构材料。钛合金攻螺纹切削时刀具极易磨损，刀具寿命很短。通过对钛合金攻螺纹过程受力分析，将丝锥直槽变为螺旋槽，可以使切削热和切削力不至于过分集中于切削刃附近，改善散热条件，也可加强切削刃，减少崩损。【关键字】钛合金、攻螺纹、金属结构材料、热处理强化、丝锥直槽、螺旋槽钛合金是一种比重小、强度高、耐腐蚀和耐热等特性的金属结构材料。TA7属单相组织的型钛合金，不能热处理强化，通常在退火状态下使用，具有良好的热稳定性和热强性。TC4属双粗组织的型合金，有较高的力学性能和高温变形能力，良好的韧性和塑性，能进行各种热加工和热处理强化。钛合金在100150仍有很高的强度，被广泛应用于火箭发动机外壳、航空发动机气机盘、叶片、结构锻件等。1.钛合金攻螺纹切削过程特点钛合金是一种难切削材料，突出特点是刀具极易磨损，刀具寿命很短。主要体现在：（1）切削层变形小由于钛合金的塑性低和钛的化学活泼性高，在高的切削温度下化学亲和性很强，容易与大气中的氧、氮等元素化合，从而脆性降低，切削变形小。（2）切削温度高钛合金导热性很差，导热系数只相当于45钢的1/51/7切削热不容易传出，集中在切削区和切削刃附近较小范围内。（3）冷硬现象严重一是切削过程中产生的塑性变形，另一方面在高的切削温度下，钛很容易吸收空气中的氧和氮形成硬而脆的外皮，冷硬现象不仅会降低零件的疲劳强度，而且能加剧刀具磨损程度。（4）刀具容易磨损主要有机械磨损：毛坯余量和组织不均匀，硬皮与刀具表面接触发生强烈的机械摩擦，使刀具受到不均匀的负荷造成崩刃现象。此外切削过程中已加工表面较大的弹性恢复，也使刀具磨损。粘接磨损：钛合金对刀具材料的亲和性很强，在切削温度高和切削力大的条件下，很容易与刀具中的某些元素如C、Ti、Co等粘附在一起，随切屑的流出带走刀具材料中的质点。2钛合金攻螺纹过程受力分析及改善措施（1）切削层变化带来的丝锥受力不均匀丝锥攻螺纹过程属于半封闭式多刃薄切削过程，与车削螺纹相比较，切削条件恶劣。在工件底孔内切出的螺纹，是由丝锥切削刃瓣上的各切削牙逐层切削而成的。不难看出，丝锥或工件旋转一周后，每个切削牙都前进一个螺距，并分别从工件上切除一层金属。用机用丝锥攻螺纹时，随着丝锥切入孔中，切削层总面积逐渐增加。当切削锥全部进入孔中工作时，切削层总面积达到最大值。当丝锥再继续前进时，由于校准部不起切削作用，所以切削层总面积不再增加。对于钛合金来说，因切削层巨大的摩擦力和塑性变形给运动中的丝锥受力带来了波动。一个最有效的改变办法是将螺纹孔底孔直径增加到所允许的上限，最大程度地减小切削层厚度。（2）“陷切”造成的丝锥受力恶化攻螺纹时，作用在丝锥各切削刃上的切削力可分解为轴向力、径向力和切向力。切向力直接决定攻螺纹扭距的大小，其他两个分力则影响攻螺纹的切削过程。从图2中可以看出，开始攻螺纹时，丝锥依靠在工件上切出的JI螺纹侧面被引导前进。但因JI面太小，加之钛合金塑性变形，承受不了丝锥对工件的轴向力而产生接触变形，使丝锥的轴向前进量不足，各刃瓣滞后并在螺纹表面一侧切出阶台而造成“陷切”现象。攻螺纹继续进行时，在由KJ、GH、GF、CD等侧刃、顶刃切削时产生的轴向力合力Fa(-)和由JI、EF、AB等侧刃切削时产生的轴向力合力Fa(+)未趋平衡以前，“陷切”现象将继续发生。但随着丝锥与工件相接触的螺纹引导表面的增大，“陷切”量将逐渐减小；攻螺纹的“陷切”现象直接影响螺纹一侧面的正确成形，并使其表面粗糙度值高，严重时足以啃住丝锥，使之处于抱死状态。（3）攻螺纹过程中的摆动容易使丝锥单向嵌入工件基体中在丝锥正常工作的条件下，如前所述，由于同时工作的丝锥各切削牙切削宽度不等，使前面切削牙的切削面积大于后面切削牙的切削面积，所以，作用在丝锥各刃瓣上的径向力不等，也使径向力的合力不等于零（）。显然，在攻螺纹时，丝锥将偏向径向力小的一边，丝锥的轴线相对于孔的轴线将发生偏移，导致被加工的螺孔扩大同时也使丝锥紧贴在一边。当丝锥的切削锥长度较短，即导角较大时，各刃瓣上切削牙的切削宽度差别愈大，中径扩大的可能性越大，故丝锥的切削锥长度不宜太短。（4）攻螺纹扭矩的非稳定性攻螺纹的扭矩由三个部分组成，即切削扭矩、丝锥与已加工螺纹间的摩擦扭矩和由于切屑堵塞在容屑槽内产生的扭矩。在正常切削的条件下，攻螺纹扭矩主要是切削扭矩，后一种扭矩所占的比重一般很小，可忽略不计。丝锥在通孔中攻螺纹时扭矩的变化情况。随着丝锥切入底孔，进行切削的牙数增加，攻螺纹扭矩增大。当切削锥全部进入底孔时，扭矩达到最大值。当丝锥的切削锥从孔的另一端露出时，攻螺纹扭矩开始减小。显而易见，攻螺纹扭矩基本上与丝锥切削层总面积成正比，攻螺纹扭矩的变化规律与丝锥切削层总面积的变化规律大致相同。为了避免在扭矩最大值时用力过猛，必须掌握所施加扭矩大小及缓急程度。另外还可以通过以下途径来有效地减小攻螺纹扭矩：1、增大前角使攻螺纹扭矩减小，例如前角为时，假设扭矩为100%，那么当前角变为时，则扭矩就减小到70%，前角时扭矩仅达到原来的53%，但是增大前角会使丝锥强度降低，也不利于散热，这一点应注意。一选择尽可能少的丝锥刃瓣数即槽数，这是因为槽数的增加，一方面使切削厚度变薄，难以切削，另一方面增加了丝锥与工件摩擦面积，使丝锥扭矩变大，一般的四槽比三槽约增加8%的扭矩。二选择对口的切削液，减小摩擦。如浓度较大的硫化油，添加15%20%的四氯化碳，可降低表面粗糙度值和减小丝锥咬死的可能性。3丝锥前面导向部分的导角既不能过大也不能太小，导角过大，切削层厚度大，受力容易崩牙咬死，切屑也不易卷曲，但导角过小，切屑过薄，在硬化层上摩擦，加剧丝锥磨损。另外丝锥校准部分不宜过长，否则和螺纹孔壁摩擦将会加剧，一般为45个螺距。4丝锥改进实例由于钛合金材料在加工过程中容易产生表面加工硬化，特别是加工小直径螺纹孔，成了难题。攻螺纹时由于缩孔，攻上几扣，就抱住丝锥，切削力特别大，普通丝锥容易折断，使工件无法继续加工。基于上述受力分析过程，将丝锥的大径、中径、小径磨小并分为四个等级，每只丝锥相差0.1mm，以期减少切削力带来的影响，但是由于切削量小，工件又容易产生加工硬化，加工起来比较费劲，效率很低，攻上几个螺纹孔就不能继续使用了。后来我从改变切削的角度入手，经过多次反复实验，将丝锥直槽变为螺旋槽，即在原切削牙上按螺旋角度磨去12扣，以减小丝锥与切屑的接触面积。前角由原来的减少至，使切屑与前刀面的接触长度小，既可以增加切屑与前刀面的接触面积，使切削热和切削力不至于过分集中于切削刃附近，改善散热条件，也可加强切削刃，减少崩损。参考文献: 1 高钟锍.机电控制工程M.北京:清华大学出版社,2002.2 张建民.机电一体化系统设计M.北京:北京理工大学出版社,2002. 3 王贵明.数控实用技术M.北京:机械工业出版社,2000.The alloy of titanium attacks whorl technologyand screwtap to improveAbstract Titanium is of small specific gravity , high strength, strong corrosion resistance and heat resistance ,which are the characteristics of metallic structural materials. Titanium is a kind of material easily tapped cutting tool wear, shorting its using time . Titanium is tapping on stress analysis, tapping directly into the spiral groove that can make cutting heat and force without being unduly concentrated in the vicinity of the cutting edge ,not only improve heat dissipation, but also strengthen the cutting edge, in order to reduce losses collapse.Key word Titanium, Gewinde scheiden, metal structural materials, heat resistance, Straight Fluted Taps, spiral chuteTitanium alloy is a kind of metal structural material , with characters of small proportion , high intensity, strong corrosion-resisting and heat-resisting and so on . TA7 belongs to the organized single-phase type of titanium alloy , which cant be strengthen under the heat treatment, used under the condition of putting out the fire in common situation , with good performence of hot stability and intensity . TC4 belongs to organized double-thick of type titanium alloy , which has higher mechanics performance and the ability of deformed under high temperature, good toughness and plasticity, which can work with all kinds of heat process and strengthen treatment. Titanium alloy still has very high intensity under. It is widely used in the outer shell of rocket engine, aviation engine chassis, blade, structural forging,etc.1. The characteristics of the titanium alloys Gewinde scheiden whorl cut the process:The titanium is a material which is very hard to cut. The outstanding characteristic is that the cutting tool is very easy to be polish and its life-span is very short . Main reflects are as following : (1)Cut layer can transfigure small because Titanium alloy is plasticity lowness and the titanium chemistry is activity . Under the high temperature of cutting that have strong affine of chemistry and easy combination with element chemical such as oxygen , nitrogen easy to hit the target with atmosphere. It is brittleness lessening , cutting deformation are minor.(2)Cut temperature high titanium alloy heat conductivity very bad, heat conduction coefficient whether 45 steel of 1/51/7s cut hot only, in smaller range near concentrating on the cutting area and cutting the edge.(3)Cold hard phenomenon serious one cut out of shape plasticity that course produce, on the other hand at high cutting temperature, titanium very apt oxygen and nitrogen to absorb air form hard and fragile crust, the hard phenomenon of cold not only will reduce fatigue strength of the part but also can aggravate the cutter and wear and tear the intensity.(4)The cutter is apt to wear and tear and mainly have machinery that is worn and torn: Blank surplus and organization even, hard skin with cutter surface exposed to, take place strong machinery rub, make the cutter caused and broken out the edge phenomenon by the load not even. Cut course process surface loud elasticity resume, make the cutter wear and tear too already. Sticking wears and tears: Titanium alloy affinity of material very strong to cutter, in cut temperature to be high cutting strength under the heavy terms, it is very easy to seize with some elements in the cutter such as C, Ti, Co,etc. together, with flowing out the particle taken away in the cutter material of smear metal.2. Titanium alloy attacks the whorl course and is analyzed and improved the measure by strength.(1)Cut layers of screwtap that change bring specialize in strength even screwtap whorl course belong to semi-closed many edge thin to cut the course, compared with whorl of turning, it is abominable to cut the condition. Whorl that cut out in work piece underport, to cut by screwtap edge every of petal cut tooth chase layers of cut, as shown in Fig. 1. It is easy to find out, after the screwtap or work piece rotates a circle, each one cuts the tooth and advances a pitch, and excise a layer of metal from work piece separately. Specialize in whorl, cut hole with machine with screwtap with screwtap, cut one layer of the whole area increase. When cutting all awls and entering and working in the hole, cut one layer of the whole area and reach the maximum. When the screwtap continues advancing again, do not play a cutting role because of the department of regulating, cut one layer of the whole area to no longer increase. To alloy of titanium, cut layers of enormous frictional force and plasticity deformation give screwtap of sport bring, fluctuate strength. A most effective change method increases underport diameters of hole of the whorl to the upper limit allowed, reduce and cut one layer of thickness to the greatest extent.(2) Fall into, cut screwtap that cause worsen, specialize in whorl, act on in screwtap cutting strength cutting strength at the edge can resolve axial force, radial strength and tangential force into each , as shown in Fig. 2. Tangential force determine, specialize in whorl size to sprain distance directly, other two component force influence cutting course to specialize in the whorl. Can find out begin specialize in whorl, JI that screwtap rely on at work piece cutting out lead, advance to the side of the whorl in 2 Fig. But because JI too light, in addition titanium alloy plasticity out of shape, bear screwtap axial force in work piece produce, keep in touch out of shape, make the axial of the screwtap insufficient in advancing amount, every edge one lags behind and cuts out the steps platform and causes the fall into and cut phenomenon on one side of the surface of whorl. Specialize in whorl continue go on, by KJ, GH, GF, CD side edge, carry edge axial force that produce join forces cut, join forces Fa by JI, EF, axial force that AB produce when the side edge is cut ), trend towards before such as equilibrium, fall into and cut the phenomenon will continue taking place . But the whorl contacted with the screwtap and work piece guides superficial increase, fall into and cut quantity will be reduced gradually ; Attack falls into and cuts the phenomenon influences the taking shape correctly of a side of whorl directly ing of whorl, make surface its roughness enough to gnaw live in screwtap when being value serious high, make it in, embrace state extremely.(3)Specialize in whorl swing of course apt to make screwtap to be one-way to imbed work piece of the matrices on terms that the screwtap work normally, as noted previously, because the screwtap working at the same time each cuts the tooth and cuts the width, make the cutting area of cutting the tooth above cut the cutting area of the tooth in the back of greater thanning, so, the radial strength of acting on screwtap every edge one makes the resultant of forces of radial strength not equal zero（）As shown in Fig. 3. Obviously, while attacking the whorl, screwtap agree more on radial to be strength little axis axis in hole of screwtap take place skew, cause, expand at the same time making screwtap stick to aside closely spiral shell hole that process. Cutting in screwtap awl length relatively short, lead when angle heavy, every edge cut cutting of tooth width difference loud at the petal, the bigger possibility China expanded directly, so the awl length of cutting of the screwtap should not be too short.(4)That attacked torsion of whorl is not that the torsion that stability attacks the whorl is made up of three parts, cut torsion, screwtap with process friction torsion of whorl already and because smear metal stop up in torsion that bits produce in the trough of holding. Under the terms of cutting normally, it mainly cuts the torsion to attack the torsion of whorl, the last one proportion that torsion account for generally very light, can ignore. In Fig. 3 is the change of the torsion while attacking the whorl in the open hole of the screwtap. Cut underport with screwtap, tooth cut to go on count, increase, specialize in torsion of whorl increase. When cutting all awls and entering the underport, the torsion reaches the maximum. When the cutting awl of the screwtap emerges from another end of the hole, specializing in the torsion of whorl begins to reduce. Obviously, specialize in whorl torsion cut one layer of the whole area directly proportional to with screwtap basically, specialize in whorl change law and screwtap of torsion cut layers of change of the whole area law roughly same. In order to avoid exerting oneself in the torsion maximum too quicklily, must grasp the torsion size and pressing or otherwise intensity exerted. In addition it come, reduce, specialize in whorl torsion effectively through following route: One. It is before it increase for horn make specialize in there arent whorl the torsions,such as before horn, suppose torsion have 100%, angle turn into, torsion reduce get 70% then, the torsion only reaches original 53% when the the previous corner at present then, but the angle will make the screwtap intensity reduce before increasing, unfavorable to dispelling the heat, this should notice.Two. choose screwtap edge petal that lack as much as possible count the trough is counted promptly, this is because the increase that the trough counted, make, cut thickness thin, difficult to cut, increase screwtaps and work piece rub the area on the other hand on one hand, make the torsion of screwtap large, four general troughs nearly increase 8% of the torsion than three troughs.3 .Chooses the fitting cutting liquid, reduce the friction. Such as density heavy vulcanization oil, add 15%0% tetrachloromethane, can reduce surface roughness value and reduce possibility that screwtap kill.45, Whom screwtap lead partly lead angle can too little either, lead angle to be too big, cut layers of thickness heavy, strength being apt to break out tooth kill, the smear metal is difficult to be curly, but lead horn to be too light, smear metal too thin, rub on hardening layer, aggravate screwtap wear and tear. In addition the calibration part of the screwtap should not be too long, otherwise rub against whorl hole wall and aggravate, it is generally 4 pieces of pitch.4.The screwtap improves the embodiment and is prone to the work hardening of surface in the course of processing because of the titanium alloy material, especially process the small diameter whorl hole, become the difficult problem. Specialize in whorl, because of contract hole, several deduct attack, embrace screwtap, cut strength to be very much heavy, the ordinary screwtap is easy to break, make the work piece unable to continue processing. Because of described above to receive strength analytic process, large foot-path, hit foot-path, path rub
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