曲轴箱轴承孔端面螺纹底孔组合钻床及夹具设计【含CAD图纸、说明书】
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压缩包内含有CAD图纸和说明书,咨询Q 197216396 或 11970985摘 要一个国家的发展主要依赖工业生产,工业生产的发展水平决定着这个国家的未来发展方向。先进的制造设备是最直接能够提升生产力的。本文所要详解的是曲轴箱轴承孔端面螺纹底孔的加工方法及其加工用的组合钻床。此工艺要求同时加工曲轴箱左右两端12个螺纹底孔,并且一次性达到所要求的加工精度。按照以上要求,设计出三图一卡,装配图及夹具。卧式组合钻床构成零部件大致为滑台底座、液压滑台、多轴箱、夹具,附带动力元件等等。本文主要涉及机床部件标准件的选取,涉及夹具,多轴箱齿轮的配对及校核。关键词:组合钻床,轴承孔端面,多轴箱,夹具 AbstractThe development of a country depends mainly on the industrial production, and the development level of the industry determines the future development direction of the country. Advanced manufacturing equipment is the most direct to enhance the productivity of.T This paper will explain the combination drilling machine processing method of crankcase bearing hole face and threaded hole for processing. This process requires simultaneous processing of the crankcase around 12 ends of the threaded hole, and attains required processing precision. According to the above requirements, the design of a three figure 1 card, assembly drawing and fixture.Horizontal combination drilling machine components generally slide base, hydraulic slipway, multi axle box, fixture, incidental power components and so on. This paper mainly involves the selection of standard parts of machine tools, involving the fixture, the matching of multi axle box and check.Keyword: Combination drilling machine, end face of bearing bore, multi axle box, clamp目 录摘 要2Abstract31绪 论42.组合机床的总体设计62.1 组合机床方案的制定62.2 确定切削用量及选择刀具82.3 “三图一卡”的编制92.4 多轴箱的设计183.夹具设计213.1 机床夹具的概述213.2工件结构特点分析213.3工件定位方案和定位元件的设计223.4夹紧方案和夹紧元件的设计223.5夹具体的设计223.6误差的分析与计算223.7夹具精度分析计算234 .结 论24致 谢25参考文献2623Abstract第二章 组合机床的总体设计1绪 论1.1综述本课题国内外研究动态,说明选题的依据和意义21世纪制造业迅速发展,生产效率决定企业的存亡,提高机床的生产效率,降低生产成本,使得企业最大化利益化是每个生产企业关注的。随着时代发展,工程师们首先发明了专用机床提高生产率,其缺点制造成本高,设计周期长,通用性低。多年后,工程师们改善了传统的机床,即如今的组合机床,大大提高了生产效率,降低了劳动率。组合机床的特点为一次性可以多把刀具加工或同时加工多个工序,产品质量也是有增无减;一般的组合机床由标准零部件组成,方便零件更换减少生产成本;组合机床能够实现联合组成自动化生产线,实行大规模生产。如今,组合机床可以保证高质量,高产量,高效率的车间生产。组合机床自动化程度非常高,只需少数工人加工操作。国内的大中型箱体类零件的钻孔,扩孔等大部分用组合机床加工。近年来,组合机床行业日益壮大。1.2.组合机床的种类与用途1911年,美国人发明了世界上第一台组合机床。当时只是用在汽车行业,人们发现其加工效率很高,没过多久,组合机床遍布世界各地大小工厂中。28年前,我国刚开始只有小规模地生产,如今,组合机床被用于大大小小各个行业。组合机床是提高效率,工业发展的完美探索者。组合机床自动化程度比较高,高效,易加工,已经成为机械行业的新鲜血液。1.3.组合机床的发展与前景我国的组合机床生产水平属于世界中游,国内大型,多工位的的组合机床不得不从国外引进。在21届日本国际机床博览会中上, 许多国家展示了当时最先进的组合机床,国内专家们现在还对当时展示的多功能的设备大为观止。当时列出的组合机床,最高的主轴转速每分钟18000转,进给速度达到每分钟50米。现在生产质量要求愈来愈高,零件也愈来愈复杂,现今水平的组合机床可以做到化繁为简,化难为易,组合机床在机械行业的前景是不能想象的。 组合机床的发展趋势是自动化,多样化,随着科技的发展,自动化技术的日益成熟,组合机床自动线也越来越数字化,未来的发展趋势是机床可以实行无人操作,从工件的装夹,零件的加工,再到工件的拆卸,机床自动实行,可以大大提高生产力,降低劳动强度。现今,工件的形状越来越复杂精细,加工要求越来越高,单工序机床今后将无法满足每日大批量的生产,多工序多样化得组合机床将会是未来趋势,机床可以多工序加工,还可以同时进行钻孔,铣面等。我国的综合实力日益壮大,工业发展也紧追欧美大国,组合机床生产发展也日益蓬勃。第二章 组合机床的总体设计2.组合机床的总体设计2.1 组合机床方案的制定2.1.1确定加工工艺方案每一道工序,每一环节都需要有零件加工的要求、目标,加工工艺方案便是零件加工生产的依据。每一道工序都会有一个加工工艺方案,零件加工时,我们需拟定合理的工艺方案出来。生产在制定工艺方案时,首先要仔细查看零件图纸,要清楚知道工件的轮廓、材质等;还要知道工件要加工哪一个或哪些部位,加工的精度要求等;初步确定工件加工时如何定位、夹紧,估算切削量等等。最后查看中英文的相关资料,拟定出合理的工艺方案。分析被加工零件(曲轴箱轴承孔端面),写出螺纹底孔的工艺过程。 (1)技术要求曲轴箱左右端面轴承孔上的螺纹底孔的加工,共计6X2=12个,工件材料为HT200(灰铸铁),硬度为HB163255。 (2) 工艺分析孔的位置度公差为0.1mm。根据实际生产经验,为了提高加工效率,减少生产成本,螺纹底孔的加工同时一步完成,M8螺纹孔低孔直径查表计算取6.5毫米,加工的孔深为16毫米。(3) 定位基准的确定和选择合适的夹紧点综合分析被加工零件的特征和加工的部位,最后确定以箱体的底面为定位基准,选取底座对角长度最大的两个孔定位,一面两销(圆柱销、菱形销)定位可以限制工件个六自由度, 且此组合钻床配有该曲轴箱的专用夹具。(4)生产量年生产量不少于60000件。2.1.2 确定组合机床结构方案(1)被加工零件的加工精度在完成机床结构方案时,我们要保证加工零件可以完成要求的加工工序,并且要保证加工精度。曲轴箱轴承端面螺纹孔的不需要特别高的加工精度,可以使用一般组合钻床。在加工时,可以对所有孔同时进行最终的精加工。为了使得加工出来的孔粗糙度在Ra3.0um内,我们要精确计算零件的尺寸大小,夹具的定位误差等,提高制造精度。最后,我选择尾置式齿轮动力装置的组合机床,采用液压系统进给,夹具设计为手工夹紧。 (2) 被加工零件的特点轴承孔端面的材料HT200、硬度HB163-255,6个孔以轴承孔中心为圆心环状均匀分布,孔的直径为6.5毫米。经分析,零件加工时受力不大,加工处发热等影响微乎其微。确定单面6个孔可以同时加工,双面同步进行,一次完成的方案。实际生产中,被加工面与定位基准面垂直的一般选择卧式机床,立式机床一般不加工长度偏高的工件,且工件的被加工平面与工件的定位基准面是平行的。此工件的被加工面与定位基准平面是垂直的,6个孔一次同步完成,一个工序,最后确定卧式单工位组合钻床。(3) 零件的生产批量零件的生产批量也会影响到机床的设计。此工件年生产量6万件,多轴头同步加工,可以大大减少生产周期,从而提高效率。(4) 机床使用条件最后,还需去工厂车间作实地考察,查看车间大小,所需机床数量,还要考虑客户的要求,再综上考虑,给客户提供多个选择方案。综上所述:从以上各个方面综合考虑,工件的结构,用户要求等等,最终,我优先选用六轴头单工位同步钻床。2.2 确定切削用量及选择刀具2.2.1 选择切削用量确定了工件的工艺方案和机床的种类,下来就要考虑选择切削用量。在实际生产中,机床同时加工的轴越多,切削用量会少25左右。组合机床的进给系统选用动力滑台。由于要被加工的孔的深度是一致的,所以每个刀具的进给量也是一致的,满足NixFi=NjxFj。同时,我们还可以计算出动力滑台每分钟进给量Vf=NixFi。式中:Ni,Nj各主轴转速(r/min) Fi,Fj各主轴进给量(mm/r)所生产的每个曲轴箱轴承端面的工件材料、精度、技术要求完全一样的。综合效率和成本考虑,最后选取钻头直径选取D=6.5mm,材质选择高速钢。综合加工效率,刀具磨损情况考虑,选取刀具进给量f=0.1mm/r,同时为了一次达到加工精度要求,选取切削速度v=10m/min。2.2.2 切削力、切削扭矩、切削功率的(1)通过切削力的计算,可以计算出滑台的最小进给力:布氏硬度:HB =HBmax-(HBmax-HBmin)/3 =255-(255-163)/3 =224.33式中: HB布氏硬度切削力:F=26D f0.8HB0.6 =26X6.5X0.10.8X224.330.6 =689.32N式中: F切削力(N)D钻头直径(mm) (2)主轴及传动轴的选取主要由切削扭矩决定:切削扭矩:T =10D1.9f0.8HB0.6 =10X6.51.9X0.10.8X224.330.6 =1429.12Nmm式中: T切削扭矩(Nmm) f进给量(mm/r) (3)动力箱主要依靠切削功率和主轴转的速选择的:切削功率:P=TV/(9740X3.14XD) =(1429.12X10)/(9740X3.14X6.5) =0.072 kW 转速:n=1000v/(3.14Xd) =1000X10/(3.14X6.5) =490r/min 式中:V切削速度(m/min) P切削功率(kw)n转速(r/min) 2.2.3 选择刀具结构如何选择刀具结构:1、优先选择标准刀具,因为标准刀具结构比较简单,刃磨也比其它刀具容易的多。2、我们还要考虑到钻孔时废料的排除,选择的刀具是否每个部位都可以切削。该轴承孔端面的硬度在HB163255,加工孔径为D=6.5mm,我选择高速钢钻头(W18Cr4V),直径为6.5的麻花钻。最后,刀具长度的确定,我们要保证在工件加工完成时,刀具尾端与刀导套之间要保持35至45mm的距离,方便刀具长度的调整。2.3 “三图一卡”的编制“三图一卡”是对工件加工最简单也是最直的展示方式,其包括零件工序图,加工示意图,尺寸联系图及生产率计算卡。2.3.1零件工序图1、如何拟定零件工序图零件的的工序图取决于前面所拟定的工艺方案,明确表达了组合机床所要完成的任务及任务要求,如加工部位尺寸,定位基准等等。零件工序图不光光是简单的一张工件三维图,它要求我们标出工件尺寸,加工部位的尺寸,定位基准,还要有夹紧位置,再加上必要的文字说明。它是组合机床设计中必不可少的一部分。明细如下:(1)零件图中,要明确画出正确的零件形状,重要部分需要用剖面图表达出来,标注零件尺寸,加工部位尺寸,精度要求,表面粗糙度等等。(2)要在图上标明该工件的定位基准,夹紧位置,还要有夹紧方向等等。(3)如果会用到中间向导时,我们还应清楚了解中间向导与工件的联系尺寸,查看各个元件之间是否会干涉或其他问题。 (4)最后,再补充一些细节的东西,如零件名称,材质等等。2、绘制被加工零件工序图(1)零件工序图的前提是简单,直观,明了,做到该多不多,该少不少,着重表现出加工部位和加工要求。画图时,选择适当的比例,画出三视图及重要部位的剖面图,还需表达出工件的外轮廓,加工部位的尺寸等等。最后,使用相应的符号标记出定位基准,夹具加紧位置和方向。(2)标注加工部位的尺寸时,我们需要由定位基准启始,方便工人快速理解图意。(3)最后,还需表达出零件加工时的特定要求。2.1.2零件工序图2.3.2 加工示意图1、绘制加工示意图零件工序图完成之后,我们需要根据拟定的工艺方案绘制出加工示意图。加工示意图与零件工序同不同的是,它主要展示的是零件如何加工,怎么加工。它还展示了零件,夹具,多轴箱之间的距离大小,机床的工作循环等等。加工示意图还将影响多轴箱的设计,动力元件的选择,机床的整体结构。加工示意图的组成:(1)要明确表达出设计师的设计思路,选定切削参数,设计出加工时滑台刀具的快进,快退长度等。(2)在图中,还要正确的将重要尺寸数据标注出来,如主轴的外伸长度,刀导套的尺寸等。(3)绘制刀具时,刀具应在加工完了的位置。2.3.2加工示意图2、选择刀具、工具、导向装置(1)刀具的选择 刀具优先选用标准件,要考虑的工件的材料,需要的精度,加工数量等等。(2)导向套的选择 导向套是用来辅助保证机床钻孔时的位置精度,导向套主要由刀具决定的,包括类型和参数。1)选择导向类型 刀具直径为6.5mm,主轴转速为490r/min,根据实际生产经验选择固定式导向。2)导向套的参数 查表得,导向套的内径应为6.5mm,外径取12mm,长度不少于18mm,衬套外径为16mm。(3)固定装置的配合 刀具和固定装置为间隙配合,固定装置内径的公称尺寸偏差为G7或F8;固定装置和衬套也为间隙配合,固定装置外径的公称尺寸偏差为H7/g6,衬套内径的公称尺寸偏差为H7/js6.(4)主轴的选取综合考虑实用性,主轴我们选取40Cr。查表得,剪切弹性模量G=81.0GPa,刚性主轴取14(0)m,B取7.3,计算出主轴的最小直径d:dB(10XT)0.25=7.3X(10X1.42912)0.25=14.19mm式中:d轴直径(mm) T轴所承受的转矩(Nmm)从上面的计算我们可以知道主轴的直径必须大于14mm,6个主轴相同,取D=32mm, 主轴外伸长度初步取L=115mm,查表得主轴内径取d=20mm。(5)选择刀具接杆 多轴箱端面到每个加工孔表面的距离是相同的,主轴外伸长度L=115mm也相同,且加工的孔深相同。所以刀具应选择同一种,刀具长度是相同的,然而实际生产中,往往6把刀具的磨损情况不一样,刀具会出现微小的参差不齐。为了避免加工后,6个螺纹底孔深度不一样,甚至无法进行下到工序,所以我们要在刀具和主轴上在装个可以调节长度的元件,我们选择可调式刀具接杆。2.3.2可调连接杆如图,连接杆左端与主轴连接,连接杆嵌于主轴内,所以连接杆左端大小等于主轴内孔直径大小,即d=20mm。(6)机床的联系尺寸计算示意图尺寸时,我们选取的是刀具钻完孔时的尺寸来确定其它尺寸。在这里,我们可以计算出加工完成后加工表面与多轴箱表面的最小长度Lmin。Lmin=L刀具+L连接杆+L主外+L螺母-L孔深。(7)工作进给长度的确定 工作进给长度L=L1+L2,L1为加工部位长度,L2为刀具切入长度。由于工件端面误差等情况,切入长度L2=5-10mm,在这里取L2=9mm,所以L=16+9=25mm.(8)快进长度的确定 在实际加工中,装卸工件时,刀具要回退出零件夹具外,要保证最大回退时刀具不会触碰任何工件,留出一段空间长度,在这里,快速退回行程取157mm,快退长度=156-25=131mm。2.3.3 机床联系尺寸图2.3.2联系尺寸图1、联系尺寸图的作用和内容组合机床主要由多轴箱,滑台底座,动力箱组成,它们之间相互独立又相互合作。动力箱为动力元件,带动驱动轴传动轴主轴;普通组合机床一般选用液压滑台,进给力大,工作未定;多轴箱根据所要加工的零件,加工工序的不同而不同,可以进行钻孔,扩孔等一系列工序。尺寸联系图主要表达的是机床内部元件的尺寸联系,机床元件与工件的尺寸联系。它的作用是初步形成机床整体结构,包括加工工件,可以大概校核选用的零部件是否合适,查看是否可以正常加工零件等等。2、选用动力部件(1)滑台的选用 根据实际经验,选用滑台时,我们要考虑到加工时所须的进给力,最大行程等,其次,我们还要考虑滑台的驱动方式等。1)驱动形式的确定 翻阅资料知道,机械滑台变速复杂,也没有过载保护,相比之下,液压滑台使用寿命长,加工精度高,所以我优先选用液压滑台。根据加工零件的需求,我选用HY系列的液压滑台。2)确定轴向进给力 滑台所须进给力约计算F进=6X689.32=4135.92N 式中:Fi各主轴的轴向力滑台工作时,不仅仅是需要提供刀具切削时进给力,因为多轴箱底部与滑台相运动时还会产生无法避免的摩擦力。所以F滑台F进4.2KN。3)确定进给速度 与机械滑台相比,液压滑台可以在一定范围内进行无极调速。还要注意的是,由前文的切削用量计算出来的进给速度不能小于滑台工作的最小进给速度。此机床系统中进给速度Vf=nxf=49mm/min。我初步选取型号为1HY25IA的滑台,快进速度12m/min,工作进给范围32至800mm/min。4)确定滑台行程 滑台的行程不仅需要正常的工作行程,为了防止刀具磨损或定位误差等种种因素不能够进行机动性的调整,我们还应该空出前备量。1HY25型号的滑台前备量规定值为20mm。后备量的作用是在刀具过长时,也能够再向后滑移,不影响刀具的装卸,暂时取40mm。滑台的总行长度LL工+L前+L后。即:行程L156+20+40=216mm,所以取滑台工作长度L250mm,L后=L-L工-L前=250-156-20=74mm,最后确定后备量为74mm。经计算得,1HY25IA滑台符合加工要求。(2)由下式估动力箱的选用 用前文计算的轴的转动功率估算电动箱的功率,可算:P主=P切/=6X0.0720.7=0.62KW式中:多轴箱传动效率由于加工时功率的不稳定,电动箱的实际功率是要稍大于理论值的,主轴转速v=490r/min,动力箱的输出转速应大于主轴转速。所以,我选取了1TD25IA型动力箱。发动机功率为1.5kw,输出转速为520r/min。2、确定装料高度装料高度指零件下底面到地面的最小距离,为了方便工人装卸工具,装料高度大约在600至1200mm,根据我选取的滑台标准件的高度,以及方便零件的装卸,装料高度定位950mm。3、选取中间底座中间底座的大小主要由零件和夹具的尺寸决定,但也要考虑到与标准件滑台底座的联接,最后中间底座我选取侧底座1CC25。4、确定多轴箱轮廓尺寸多轴箱也是标准件,主要依据主轴的位置大小来决定,也须考虑到与其他标准件的联接,经计算和查表,多轴箱的尺寸选取400X400。2.3.4 生产率计算卡计算生产率计算卡主要表达的是工件从安装到加工结束后卸下的各个子过程的所需时间,还有切削用量,刀具转速等。最后计算得出机床每小时的生产率和负荷关系。1)理想生产率Q Q=60000/K=60000/2350h=25.53件/h 式中:Q机床的理想生产率(件/h)K单班制工厂选取23500h 2)实际生产率Q实 Q实=60/T单 T单=t切+t辅+(Ls/Sm+T停)+(l快进+l快退)/V快+T移+T装卸=(25/224.8+10/1124)+9140+165)/8000+0.1+1.5=1.76mim式中:T单 每个工件加工所需要的时间(h) Ls进给的行程长度(mm)Sm每分钟进给量(mm/min)T停死挡铁停留时间 V快动力部件快速行程速度T移工作台完成一次工位的转换时间(min)T装卸装卸工作时间(min)所以Q实=60/T单 =60/1.7634.1 件/h3)机床负荷率=Q/Q实=25.53/34.1X100%=74.87%式中:A年生产纲领(件) Tk年工作时间(h)2.3.4生产率计算卡被加工零件图号毛坯种类铸件名称曲轴箱轴承孔端面毛坯重量材料HT200硬度HB163-255工序名称加工M8螺纹底孔工序号工时/min序号工步名称工作行程/mm切速/(mmin-1)进给量/(mmr-1)进给量/(mmmin-1)机动时间辅助时间1装入工件0.52工件定位、夹紧100.253右力部件快进131100000.0114右力部件工进25100.1490.95死挡铁停留0.0096右力部件快退156100000.0217松开工件100.258卸下工件0.5备注1、 装卸工件的时间取决于工人的熟练程度,取1.5min;2、 直线移动或回转工作台进行一次工位转换时间,取0.1min.累计0.111.571单件总工时1.681实际生产率25.53件/h理论生产率34.1件/h机床负荷率74.87%2.4 多轴箱的设计2.4.1 绘制多轴箱设计原始依据图由图所示,以左下角的定位销中点O为原点,以中心点垂直于多轴箱右端面为X轴正方向,以垂直于X轴向上为Y轴正方向。最上端的孔为孔1,顺时针分别为孔2,3 , 4 , 5 , 6 ,此图为多轴箱原始依据图,以此进行轴的位置及计算。2.4.1 钻孔组合机床多轴箱原始依据图主轴外尺寸及切削用量轴号主轴外伸尺寸工序内容切削用量D/dLN(r/min)V(m/min)f(mm/r)Vf(mm/min)1、2、3、4、5、632/20115钻6.5490100.1492.4.2 齿轮模数选择组合钻床一般选用滚珠轴承主轴。由计算得齿轮模数m应大于等于2,查表得,驱动轴齿轮齿数要求21至26,经计算,主轴传动轴的齿轮模数取m1=2,传动轴驱动轴的齿轮模数取m2=4。2.4.3 多轴箱的传动设计(1)参照原始依据图,先确定驱动轴的坐标,再计算各个主轴的坐标。计算结果如下表:驱动轴、主轴坐标值坐标定位销驱动轴O主轴1主轴2主轴3主轴4主轴5主轴6X0175175233.46233.46175116.54116.54Y094.5 285251.25183.75150183.75251.25(2)传动轴主轴由于零件加工需要,传动轴位于6个孔正中心方便传动,此级为升速传动,传动比取标准传动比1.41。 D1=m1(Z1+Z2)/2Z1+Z2=2X67.5/2Z2/Z1=1.41计算得Z1=28,Z2=40式中:m齿轮模数 Z齿轮齿数D1主轴与传动轴的轴心距(mm)(3)驱动轴传动轴驱动轴转速520r/min,要求主轴转速490r/min,所以i1xi2=490/520i2=490/(520Xi1) =490/(520X1.41) =1/1.49D2=m2(Z3+Z4)/4Z3+Z4=2X123/4Z4/Z3=1/1.49计算得Z3=37,Z4=25式中:i传动比D2传动轴与驱动轴的轴心距(mm) (4)分度圆直径计算d1=mXZ1=2X28=56mmd2=mXZ2=2X40=80mmd3=mXZ3=4X37=148mmd4=mXZ4=4X25=100mm式中:d分度圆直径(mm) (5)中心距的验算,传动轴的校核 经校核,各个齿轮可以正常啮合并且转动,并无发现齿轮间,轴之间的发生干涉情况。各轴中心距的的偏差都在合理范围内,传动轴受力校核也满足要求。2.4.4 绘制传动系统图传动系统图所展示的是各轴之间的传动关系,上面标注着各个齿轮的齿数和模数,主轴和驱动轴的转速,让看图人一目了然。2.4.4多轴箱传动系统图第三章 夹具体设计3.夹具设计3.1 机床夹具的概述3.1.1机床夹具的组成(1)定位元件和定位装置 定位装置主要是保证工件在加工时的所在坐标点在计算得出的理论坐标点上。 (2)夹紧元件和夹紧装置 加紧装置是防止工件在加工时发生位置偏移。工件仅在定位后加工是万万不可的,为了保证零件加工时保持在基准面不发生偏移,必须要用到夹紧元件或夹紧装置。(3)导向元件 导向元件即前文所说的刀导套,它的作用是能够使刀具正确地进入切削轨迹,大大提高了生产精度。(4)夹具体 夹具体顾名思义就是整个夹具的身躯,上面有着其它重要器官,它的材料通常为铸铁。 3.1.2机床夹具的类型夹具的种类繁多,外观也尽不相同,可以按工艺过程分类,可以按机床类型分类,还可以按夹具的特点适用范围分类等等。本文设计的夹具为专用夹具,其优点为定位误差小,节约生产材料。3.2工件结构特点分析本文所要加工的孔端面位置并不复杂,所以夹具的设计相对来说也并不会很复杂,所需加工的孔端面与曲轴箱底面是垂直的,所以用曲轴箱底面为定位基准就行了。3.3工件定位方案和定位元件的设计我的方案是以曲轴箱底面为定位基准,用两个支承板确定位置精度,以箱体底面距离最远的2个定位孔限制个六自由度,一面两销(圆柱销、菱形销)定位,限制所需加工孔端面与曲轴箱底面的垂直度。 3.4夹紧方案和夹紧元件的设计工件在加工中,在受到各种力的作用下,工件会左右摇晃,所以工件必须加紧,我们还要设计加紧装置。夹紧装置在夹紧过程中的要求:(1)夹紧装置不能损坏工件表面(2)夹紧力的大小不能过大使工件变形,也不能太小,失去了夹紧的作用(3)夹紧装置要易于装卸(4)夹紧装置尽量简单,加工方便分析加工零件结构,加工时切削力并不大,可以用简易夹具加紧,我采用在曲轴箱左右两侧都用螺栓加紧。3.5夹具体的设计夹具体是夹具的身躯,由于被加工零件的特点,我采用半封闭式夹具,所以夹具体的主要尺寸由工件外轮廓尺寸决定。以下是须要满足的要求:1)零件加工时,可以承受产生的切削力。2)夹具体上应考虑排屑和清理切屑方便。3)夹具体的底面要设计的比体宽大一些,可以增加稳定性。3.6误差的分析与计算该夹具以夹具体底面的上端面为定位基准,被加工螺纹孔中心轴线与右侧面的线性尺寸为一般公差。根据国家标准的规定,取(中等级)即 :尺寸偏差为 由于夹具或定位元件的尺寸误差等会产生定位误差:d.w=0.3mm 夹紧装置可能使零件表面变形等原因会产生夹紧误差 : 其中接触变形位移值: 机床,夹具经多次反复加工生产,表面会磨损造成加工误差:通常不超过 还有夹具相对刀具位置误差:取误差总和:经计算,夹具尺寸的设计满足零件加工精度的要求。3.7夹具精度分析计算最后,我们还要计算夹具精度,夹具本身尺寸的合理误差,还有定位是产生的误差,由后者产生误差主的原因:1)工件定位误差dw。2)夹具安装产生的误差a。3)刀具安装误差引起的误差t。4)因加工方法产生的误差g。为了保证加工出来的零件符合精度要求,工序尺寸公差k dw+a+t+g经计算,夹具中的定位误差dw=0.07mm,安装误差a=0.005mm,刀具位置误差t=0.07mm,加工方法误差g=0.62=0.3m。所以,按概率法相加得 经校核,此次设计的夹具及加紧方式符合要求。结论致谢4 .结 论我选取的课题是曲轴箱轴承孔端面螺纹底孔组合钻床及其夹具设计,本文主要探讨的是组合机床的设计与标准件的选取,多轴箱的传动设计,夹具设计。拿到课题,首先要大量阅读与组合机床有关的专业书籍与教材,在大概熟悉组合机床和其它零部件后,我便开始进行初步设计了。首先要明确知道加工零件所需要加工的部位,加工要求,再认真的制定出工艺方案来。通过工艺方案,可以计算出一系列重要的数据,为设计“三图一卡”打下了扎实的基础。随后,经过大量的数据运算,尺寸校对,绘制出“三图”,此时,组合机床设计部分基本大功告成。余下是多轴箱的计算和夹具的设计。本次设计的核心是机床的选取和加工方案的确定,如何降低生产成本,又能提高生产率,都在设计师的精心计算中。对于加工工件一面六孔的结构,我选择六轴头同步钻床,工作是传统机床的2倍以上,加工方便,零件精度有增无减。此次设计还有些不足,因为我是模具向的学生,对于组合机床比较陌生,可能有些工件选取的不是很正确,有些问题可能也没考虑,经过这次毕业设计,我的学习到许多东西,在日后工作中,我会加倍努力。参考文献致 谢三个月漫长的设计过程中,指导老师赵海霞悉心教导,诲人不倦,每次遇到困难,我都会去询问赵老师。身为模具向的学生,对组合机床并不是非常熟悉,加上基础不是很牢固,所谓先天畸形后天还缺钙,此次毕业设计对我来说难度是巨大的,我翻阅了大量相关书籍,但根本弄不懂是什么意思,也不会查表,非常感谢和我共同战斗的好同学,好伙伴,他们对我的鼓励与帮助也是巨大的。通过此次毕业设计,我也学习到了许多东西,毕业设计是大学以来第一次独立完成一个较大的项目,对毫无工作经验的学生来说是具有相当大的挑战性的,这将会是人生宝贵的一笔财富。青春期的我们,对未知充满着好奇,也有着战胜困难的雄心与壮志。最后,我要感谢班主任的关心与鼓励,感谢金科机电工程学院4年来对我的栽培,今天我以母校为傲,明日母校以我为傲!参考文献1 谢家瀛. 组合机床设计简明手册M.北京: 机械工业出版社,2002.2 陈立德.机械制造装备设计M.北京:高等教育出版社,2010. 3 沈阳工业大学、大连铁道学院、吉林工业学院编. 组合机床设计M. 上海: 上海科学技术出版社,1985. 4 吴宗泽. 机械零件设计手册M. 北京: 机械工业出版社,2004.5 闻邦椿. 机械设计手册M. 北京: 机械工业出版社,2010. 6 赵如福.金属机械加工工艺人员手册M.上海:上海科学技术出版社,1990. 7 孙丽媛.机械制造工艺及专用夹具设计指导M.北京:冶金工业出版社,2003. 8 李名望.机床夹具设计实例教程M.北京:化学工业出版社,2010. 9 上海柴油机厂研究所编. 金属切削机床夹具设计手册M.北京: 机械工业出版社,1984. 10 李绍珍. 机械制图M. 北京: 机械工业出版社,2002. 11 周鹏翔. 工程制图M. 北京: 高等教育出版社,2000. 12 王伯平. 互换性与测量技术基础M. 北京: 机械工业出版社,2009. 13 滕伟. 组合机床的配置形式及结构方案研究J. 装备制造技术,2011,卷( 期):05期 14 吴立梅. 组合机床发展及相关特点分析J. 科技资讯,2010,卷(期):08期 15 顾琪等. 组合机床CAD技术的研究现状及进展J.机械设计与制造,2010,卷(期):07期 16 Hung Wok Park, Young Bin Park and Steven Y. Liang. Multi-procedure design optimization and analysis of musicale machine tools J. The International Journal of Advanced Manufacturing Technology,2011, Volume :5 毕 业 设 计(论 文)外 文 参 考 资 料 及 译 文译文题目: The Lathe and Its Operations 车床及其操作 学生姓名: 学 号: 专 业: 所在学院: 指导教师: 职 称: 20xx年 2月 27日英语原文:The Lathe and Its OperationsThe Lathe and Its ConstructionA lathe is a machine tool used primarily for producing surfaces of revolution and flat edges. Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows:(1)Engine lathes(2)Tool room lathes(3)Turret lathes(4)Vertical turning and boring mills(5)Automatic lathes(6)Special-purpose lathesIn spite of that diversity of lathe-type machine tools, they all have common features with respect to construction and principle of operation. These features can best be illustrated by considering the commonly used representative type, the engine lathe. Lathe bed. The lathe bed is the main frame, involving a horizontal beam on two vertical supports. It is usually made of grey or nodular cast iron to damp vibrations and is made by casting. It has guide ways to allow the carriage to slide easily lengthwise. The height of the lathe bed should be appropriate to enable the technician to do his or her job easily and comfortably.Headstock. The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guide ways (the slide surface of the bed). The spindle is driven through the gearbox, which is housed within the headstock. The function of the gearbox is to provide a number of different spindle speeds (usually 6 up to 18 speeds). Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional, electrical, or hydraulic drives. The spindle is always hollow, i. e., it has a through hole extending lengthwise. Bar stocks can be fed through that hole if continuous production is adopted. Also, that hole has a tapered surface to allow mounting a plain lathe center. The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the like.Tailstock. The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill. The lower base is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the work piece. The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock. The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the intermediate part as required. This is achieved through the use of a hand wheel and a screw, around which a nut fixed to the quill is engaged. The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars. The quill can be locked at any point along its travel path by means of a clamping device. The carriage. The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds. It is actually an H-shaped block that slides on the lathe bed between the headstock and tailstock while being guided by the V-shaped guideways of the bed. The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw. When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations, it is the feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron. When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage, along the bed. When the lever is disengaged, the half nuts are released and the carriage stops. On the other hand, when the feed rod is used, it supplies power to the apron through a worm gear. The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole length. A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers. The quick-change gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cutting tool) travels for each revolution of the spindle can be controlled and is referred to as the feed.Lathe Cutting ToolsThe shape and geometry of the lathe tools depend upon the purpose for which they are employed. Turning tools can be classified into two main groups, namely, external cutting tools and internal cutting tools. Each of these two groups includes the following types of tools:Turning tools. Turning tools can be either finishing or rough turning tools. Rough turning tools have small nose radii and are employed when deep cuts are made. On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut. Rough turning tools can be right-hand or left-hand types, depending upon the direction of feed. They can have straight, bent, or offset shanks. Facing tools. Facing tools are employed in facing operations for machining plane side or end surfaces. There are tools for machining left-hand-side surfaces and tools for right-hand-side surfaces. Those side surfaces are generated through the use of the cross feed, contrary to turning operations, where the usual longitudinal feed is used. Cutoff tools. Cutoff tools, which are sometimes called parting tools, serve to separate the work piece into parts and/or machine external annular grooves. Thread-cutting tools. Thread-cutting tools have either triangular, square, or trapezoidal cutting edges, depending upon the cross section of the desired thread. Also, the plane angles of these tools must always be identical to those of the thread forms. Thread-cutting tools have straight shanks for external thread cutting and are of the bent-shank type when cutting internal threads. Form tools. Form tools have edges especially manufactured to take a certain form, which is opposite to the desired shape of the machined work piece. An HSS tool is usually made in the form of a single piece, contrary to cemented carbides or ceramic, which are made in the form of tips. The latter are brazed or mechanically fastened to steel shanksThis latter type includes the carbide tip, the chip breaker, the pad, the clamping screw (with a washer and a nut), and the shank. As the name suggests, the function of the chip breaker is to break long chips every now and then, thus preventing the formation of very long twisted ribbons that may cause problems during the machining operation. The carbide tips (or ceramic tips) can have different shapes, depending upon the machining operations for which they are to be employed. The tips can either be solid or with a central through hole, depending on whether brazing or mechanical clamping is employed for mounting the tip on the shank. Lathe OperationsIn the following section, we discuss the various machining operations that can be performed on a conventional engine lathe. It must be borne in mind, however, that modern computerized numerically controlled lathes have more capabilities and can do other operations, such as contouring, for example. Following are conventional lathe operations. Cylindrical turning. Cylindrical turning is the simplest and the most common of all lathe operations. A single full turn of the work piece generates a circle whose center falls on the lathe axis; this motion is then reproduced numerous times as a result of the axial feed motion of the tool. The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed. Consequently, the machined surface is always cylindrical. The axial feed is provided by the carriage or the compound rest, either manually or automatically, whereas the depth of cut is controlled by the cross slide. In roughing cuts, it is recommended that large depths of cuts (up to 0.25in. or 6mm, depending upon the work piece material) and smaller feeds would be used. On the other hand, very fine feeds, smaller depths of cut (less than 0.05in, or 0.4mm), and high cutting speeds are preferred for finishing cuts.Facing. The result of a facing operation is a flat surface that is either the whole end surface of the work piece or an annular intermediate surface like a shoulder. During a facing operation, feed is provided by the cross slide, whereas the depth of cut is controlled by the carriage or compound rest. Facing can be carried out either from the periphery inward or from the center of the work piece outward. It is obvious that the machining marks in both cases take the form of a spiral. Usually, it is preferred to clamp the carriage during a facing operation, since the cutting force tends to push the tool (and, of course, the whole carriage) away from the work piece. In most facing operations, the work piece is held in a chuck or on a face plate. Groove cutting. In cut-off and groove-cutting operations, only cross feed of the tool is employed. The cut-off and grooving tools, which were previously discussed, are employed. Boring and internal turning. Boring and internal turning are performed on the internal surfaces by a boring bar or suitable internal cutting tools. If the initial work piece is solid, a drilling operation must be performed first. The drilling tool is held in the tailstock, and the latter is then fed against the work piece. Taper turning. Taper turning is achieved by driving the tool in a direction that is not parallel to the lathe axis but inclined to it with an angle that is equal to the desired angle of the taper. Following are the different methods used in taper-turning practice: (1) Rotating the disc of the compound rest with an angle equal to half the apex angle of the cone. Feed is manually provided by cranking the handle of the compound rest. This method is recommended for taper turning of external and internal surfaces when the taper angle is relatively large. (2) Employing special form tools for external, very short, conical surfaces. The width of the work piece must be slightly smaller than that of the tool, and the work piece is usually held in a chuck or clamped on a face plate. In this case, only the cross feed is used during the machining process and the carriage is clamped to the machine bed. (3) Offsetting the tailstock center. This method is employed for external taper turning of long work pieces that are required to have small taper angles (less than 8). The work piece is mounted between the two centers; then the tailstock center is shifted a distance S in the direction normal to the lathe axis. (4) Using the taper-turning attachment. This method is used for turning very long work pieces, when the length is larger than the whole stroke of the compound rest. The procedure followed in such cases involves complete disengagement of the cross slide from the carriage, which is then guided by the taper-turning attachment.During this process, the automatic axial feed can be used as usual. This method is recommended for very long work pieces with a small cone angle, i.e., 8through 10.Thread cutting. When performing thread cutting, the axial feed must be kept at a constant rate, which is dependent upon the rotational speed (rpm) of the work piece. The relationship between both is determined primarily by the desired pitch of the thread to be cut. As previously mentioned, the axial feed is automatically generated when cutting a thread by means of the lead screw, which drives the carriage. When the lead screw rotates a single revolution, the carriage travels a distance equal to the pitch of the lead screw. Consequently, if the rotational speed of the lead screw is equal to that of the spindle (i.e., that of the work piece), the pitch of the resulting cut thread is exactly equal to that of the lead screw. The pitch of the resulting thread being cut therefore always depends upon the ratio of the rotational speeds of the lead screw and the spindle: Pitch of the lead screw/ Desired pitch of work piece=rpm of the work piece/rpm of lead screw=spindle-to-carriage gearing ratio. This equation is useful in determining the kinematic linkage between the lathe spindle and the lead screw and enables proper selection of the gear train between them. In thread cutting operations, the work piece can either be held in the chuck or mounted between the two lathe centers for relatively long work pieces. The form of the tool used must exactly coincide with the profile of the thread to be cut, i.e., triangular tools must be used for triangular threads, and so on.Knurling. Knurling is mainly a forming operation in which no chips are produced. It involves pressing two hardened rolls with rough file like surfaces against the rotating work piece to cause plastic deformation of the work piece metal. Knurling is carried out to produce rough, cylindrical (or conical) surfaces, which are usually used as handles. Sometimes, surfaces are knurled just for the sake of decoration; there are different types of patterns of knurls from which to choose.Cutting Speeds and FeedThe cutting speed, which is usually given in surface feet per minute (SFM), is the number of feet traveled in the circumferential direction by a given point on the surface (being cut) of the work piece in 1 minute.The relationship between the surface speed and rpm can be given by the following equation: SFM=DNWhereD=the diameter of the work piece in feetN=the rpmThe surface cutting speed is dependant primarily upon the material being machined as well as the material of the cutting tool and can be obtained from handbooks, information provided by cutting tool manufacturers, and the like. Generally, the SFM is taken as 100 when machining cold-rolled or mild steel, as 50 when machining tougher metals, and as 200 when machining softer materials. For aluminum, the SFM is usually taken as 400 or above. There are also other variables that affect the optimal value of the surface cutting speed. These include the tool geometry, the type of lubricant or coolant, the feed, and the depth of cut. As soon as the cutting speed is decided upon, the rotational speed (rpm) of the spindle can be obtained as follows: N=SFM/(D)The selection of a suitable feed depends upon many factors, such as the required surface finish, the depth of cut, and the geometry of the tool used. Finer feeds produce better surface finish, whereas higher feeds reduce the machining time during which the tool is in direct contact with the work piece. Therefore, it is generally recommended to use high feeds for roughing operations and finer feeds for finishing operations. Again, recommended values for feeds, which can be taken as guidelines, are found in handbooks and in information booklets provided by cutting tool manufacturers.、译文:车床及其操作车床及其结构车床是主要用于生成旋转表面和平整边缘的机床。根据它们的使用目的、结构、能同时被安装刀具的数量和自动化的程度,车床或更确切地说是车床类的机床,可以被分成以下几类: (1)普通车床(2)万能车床(3)转塔车床(4)立式车床(5)自动车床(6)特殊车床虽然车床类的机床多种多样,但它们在结构和操作原理上具有共同特性。这些特性可以通过普通车床这一最常用的代表性类型来最好地说明。车床床身:车床床身是包含了在两个垂直支柱上水平横梁的主骨架。为减振它一般由灰铸铁或球墨铸铁铸造而成。它上面有能让大拖板轻易纵向滑动的导轨。车床床身的高度应适当以让技师容易而舒适地工作。主轴箱:主轴箱固定在车床床身的左侧,它包括轴线平行于导轨的主轴。主轴通过装在主轴箱内的齿轮箱驱动。齿轮箱的功能是给主轴提供若干不同的速度(通常是6到18速)。有些现代车床具有采用摩擦、电力或液压驱动的无级调速主轴箱。主轴往往是中空的,即纵向有一通孔。如果采取连续生产,棒料能通过此孔进给。同时,此孔为锥形表面可以安装普通车床顶尖。主轴外表面是螺纹可以安装卡盘、花盘或类似的装置。尾架:尾架总成基本包括三部分,底座、尾架体和套筒轴。底座是能在车床床身上沿导轨滑动的铸件,它有一定位装置能让整个尾架根据工件长度锁定在任何需要位置。尾架体为一能横向运动的铸件,它可以调整尾架轴线与主轴箱轴线成一直线。第三部分,套筒轴是一淬硬钢管,它能根据需要在尾架体中纵向进出移动。这通过使用手轮和螺杆来达到,与螺杆啮合的是一固接在套筒轴上的螺母。套筒轴开口端的孔是锥形的,能安装车床顶尖或诸如麻花钻和镗杆之类的工具。套筒轴通过定位装置能沿着它的移动路径被锁定在任何点。大拖板:大拖板的主要功能是安装刀具和产生纵向和/或横向进给。它实际上是一由车床床身V形导轨引导的、能在车床床身主轴箱和尾架之间滑动的H形滑块。大拖板能手动或者通过溜板箱和光杆(进给杆)或丝杆(引导螺杆)机动。在切削螺旋时,动力通过丝杆提供给溜板箱上的齿轮箱。在其余车削作业中,都由光杆驱动大拖板。丝杆穿过一对固定在溜板箱后部的剖分螺母。当开动特定操作杆时,剖分螺母夹在一起作为单个螺母与旋转的丝杆啮合,并带动拖板沿着床身提供进给。当操作杆脱离时,剖分螺母释放同时大拖板停止运动。另一方面,当使用光杆时则通过蜗轮给溜板箱提供动力。 蜗轮用键连接在光杆上,并与溜板箱一起沿光杆运动,光杆全长范围开有键槽。现代车床一般在主轴箱下装备快速变换齿轮箱,通过一系列齿轮由主轴驱动。它与光杆和丝杆连接,能容易并快速地通过简单转换适当的操作杆选择各种进给。快速变换齿轮箱可用于普通车削、端面切削和螺旋切削作业中。由于这种齿轮箱与主轴相连,主轴每转一圈溜板箱(和切削刀具)运动的距离能被控制,这距离就可以被认为是进给。车床切削刀具车床刀具的形状和几何参数取决于它们的使用目的。车削刀具可以分为两个主要组别,即外部切削刀具和内部切削刀具。这两组中的每一组都包括以下类型刀具:车削刀具:车削刀具可以是精车刀具或粗车刀具。粗车刀具刀尖半径较小,用于深切削。而精车刀具刀尖半径较大,用于通过微量进刀深度来获得具有较好表面光洁度的最终所需尺寸。粗车刀具按其进给方向可以是右手型的或是左手型的。它们可以有直的、弯的或偏置的刀杆。端面刀具:端面刀具用在端面作业中加工平板侧面或端部表面,也有加工左右侧表面之分。与一般采用纵向进给的车削作业相反,那些侧表面通过采用横向进给产生。切断刀具:切断刀具,有时也称为分割刀具,用于将工件分割成若干部分和/或加工外部环形槽。螺纹切削刀具:螺纹切削刀具根据所需螺纹的横截面,有三角形的、矩形的或梯形的切削刃。同时,这些刀具的平面角必须始终与螺纹形状的平面角保持一致。车外螺纹的螺纹切削刀具为直刀杆,而车内螺纹的螺纹切削刀具则是弯刀杆。成形刀具:成形刀具有专门制成特定形状的刀刃,这种刀刃形状与被加工工件所需外形正好相反。高速钢刀具通常以单件形式制造,而硬质合金或陶瓷刀具则以刀尖形式制造。后者用铜焊或机械方法固定于钢质刀杆上。机械式固定布置方式,它包括了硬质合金刀尖、断屑槽、衬垫、卡装螺杆(带有垫圈和螺母)及刀杆。顾名思义,断屑槽的功能就是不时地折断长切屑,以防形成很长的可能会在机加工操作中引起问题的缠绕切屑条。硬质合金刀尖(或陶瓷刀尖)根据采用它们的机加工操作,可以有不同的形状。根据将刀尖装配在刀杆上是通过用铜焊还是机械卡装,刀尖可以是实心的或是带有中心通孔的。车床操作在下面这节中,要讨论的是能在传统普通车床上进行的各种机加工作业。然而,必须记住现代计算机数控车床具有更多的功能并且可以进行其它操作,例如仿型。下面是传统车床的操作。圆柱面车削:圆柱面车削是所有车床操作中最简单也是最普通的。工件旋转一整圈产生一个圆心落在车床主轴上的圆;由于刀具的轴向进给运动这种动作重复许多次。所以,由此产生的机加工痕迹是一条具有很小节距的螺旋线,该节距等于进给。因此机加工表面始终是圆柱形的。轴向进给通过大拖板或复式刀架手动或自动提供,然而切削深度则由横向滑板控制。粗车中,推荐使用较大切削深度(根据工件材料可达0.25英寸或6毫米)和较小进给。另一方面,精车则最好采用很小的进给、较小的切削深度(小于0.05英寸或0.4毫米)和较高的切削速度。端面车削:端面车削操作的结果是将工件整个端部表面或者像轴肩之类的中间环形表面加工平整。在端面车削操作中,进给由横向滑板提供,而切削深度则通过大拖板或复式刀架控制。端面车削既可以从外表面向内切削也可以从工件中心往外切削。很明显在这两种情况下机加工痕迹都是螺线形式。通常在端面车削作业时习惯于采用夹住大拖板,这是因为切削力倾向于将刀具(当然包括整个大拖板)推离工件。在大多数端面车削作业中,工件被支撑在卡盘或花盘上。开槽:在切断和开槽操作中,刀具只有横向进给。要采用前面已经讨论过的切断和开槽刀具。镗孔和内部车削:镗孔和内部车削通过镗杆或合适的内部切削刀具在内表面进行。如果初始工件是实心的,则必须首先进行钻孔作业。钻孔刀具安装在尾架上,然后对着工件进给。锥面车削:锥面车削通过沿着与车床主轴不平行而倾斜成一个等于锥面所需角度的方向进刀来实现。下面是在实际锥面车削中采用的不同方法:(1) 将复式刀架盘旋转一个等于圆锥体顶角一半的角度。通过摇动复式刀架操纵柄手动提供进给。当锥角相对较大时切削外锥面和内锥面推荐使用这种方法。(2) 对很短的外锥面采用特殊的成型刀具。工件的宽度必须略小于刀具的宽度,并且工件通常由卡盘支撑或夹紧在花盘上。在这种情况下,机加工作业时只有横向进给而大拖板则夹紧在床身上。(3)偏移尾架顶尖。对需要较小锥角(小于8) 的较长工件外锥面车削采用这种方法。工件安装于两顶尖之间;然后将尾架顶尖朝垂直于车床主轴方向移动一距离S。(4) 采用锥面车削附加装置。这种方法用于车削很长的工件,其长度大于复式刀架的整个行程。在这种场合下要遵循的步骤是将横向滑板完全脱离大拖板,然后通过锥面车削附加装置进行引导。在此作业中,能照常使用自动轴向进给。对具有较小锥角(即8到10)的很长工件推荐采用这种方法。螺纹切削:在螺纹切削作业时,轴向进给必须保持恒定速率,这取决于工件的转速(rpm)。两者之间的关系基本上由被切削螺纹所需的节距决定。如前所述,当依靠驱动大拖板的丝杆切削螺纹时轴向进给是自动产生的。丝杆旋转一圈,大拖板就行进等于丝杆节距的一段距离。因此如果丝杆的旋转速度等于心轴的转速(即工件的转速),生成切削螺纹的节距就正好等于丝杆的节距。所以被切削生成螺纹的节距总是取决于丝杆和心轴的转速比:丝杆的节距/工件所需节距=工件转速/丝杆转速=心轴到大拖板的传动比。这公式在决定车床心轴和丝杆之间的运动学关系时很有用,并且提供了正确挑选它们之间轮系的方法。在螺纹切削作业中,工件既能支撑于卡盘中,对相对较长的工件也能安装在两个车床顶尖之间。使用的刀具外形必须正好与要切削螺纹的轮廓一致,即三角形刀具必须用于三角形螺纹等等。滚花:滚花主要是一种不产生切屑的成型操作。它使用两个带有粗锉式表面的淬火滚轮压在旋转的工件上使工件金属产生塑性变形。滚花用于生成粗糙的圆柱(或圆锥)面,通常用来作手柄。有时表面滚花只为装饰之故;有不同的滚花图案类型可供选择。切削速度和进给切削速度,通常用每分钟表面英尺给出,就是一分钟内工件(被切削)表面给定点在圆周方向上行进的英尺数。表面速度与转速之间的关系可以用下式给出: SFM=DN式中D=用英尺表示的工件直径N=转速表面切削速度主要由被切削材料和切削刀具材料决定,可以从手册、切削刀具生产商提供的资料及类似的东西上查取。一般而言,SFM当机加工冷轧或低碳钢时取100,机加工较坚韧的金属时取50,而机加工较软材料时取200。对铝而言,SFM通常可取400以上。也还存在其它一些变量影响表面切削速度的最佳值。其中包括刀具形状、润滑剂或冷却液的类型、进给和切削深度。切削速度一旦确定,心轴转速(rpm)就能按下式得到: N=SFM/(D)合适进给的选择取决于许多因素,例如所需表面光洁度、切削深度和所用刀具的几何形状。进给越小生成的光洁度越好,而在刀具与工件直接接触时进给越大则可以减少机加工时间。 所以对粗车一般推荐使用较大进给,而精车则用较小进给。再者,作为指导方针的进给推荐值可以从手册和切削刀具生产商提供的资料小册子上找到。
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