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附表2：长城学院本科毕业设计（论文）中期检查表系：工程技术系 专业： 机械设计制造及其自动化 检查日期：2015年3月29日学生姓名王硕论文题目多用途小型钻铣床设计任务书已完成（），进行中（ ）参考文献 13 篇：其中外文文献 3 篇外文翻译已完成（），进行中（ ）；完成字数约： 7339 字（翻译成的汉字字数）开题报告已完成（），进行中（ ）；完成字数约： 2040 字正文已完成（ ），进行中（）；完成比比例： 20 %已完成的任务通过对相关产品的调研，搜集相关资料学习相关知识。通过资料了解产品的结构，初步拟定方案，并征求老师的指导。对比方案，确定最终方案，确定相关参数，绘出大体构架。待完成的任务整理国内外资料，分析外文资料并进行外文翻译。产品说明说的详细设计，以及零件图的绘制。存在的问题主轴箱以及进给系统的设计;时间紧任务重采取的办法通过考虑机床的承载能力，确定所需的能量参数，进行演算，得出其最大承受力，确定机床的规格，从而进一步确定主轴箱和进给系统的数据参数，从而做到对机床系统的设计。指导教师意见 指导教师签名： 注：按表中的要求填写，选项打钩（）；中国地质大学长城学院中国地质大学长城学院本科毕业本科毕业设计设计外文资料翻译外文资料翻译 系 别：系 别： 工程技术系 专 业：专 业： 机械设计制造及其自动化 姓 名：姓 名： 王硕 学 学 号： 号： 05211611 20152015年 年 4 4 月 月 4 4 日日1机械设计制造及自动化专业毕业设计（论文）外文翻译附录一Drilling and Milling Machines Upright drilling machines or drill presses are available in a variety of sizes andtypes, and are equipped with a sufficient range of apindle speeds and automatic feedsto fit the neds of most industries. Speed ranges on a typical machine are from 76 to2025 rpm., with drill feed from 0.002 to 0.020 in.per revolution of the spindle. Radial drilling machines are used to drill workpieces that are too large orcumbersome to conveniently move. The spindle with the speed and feed changingmechanism is mounted on the radial arm; by combining the movement of the radialarm around column and the movement of the spindle assembly along the arm, it ispossible to align the spindle and the drill to any position within reach of the machine.For work that is too large to conveniently support on the base, the spindle assemblycan be swung out over the floor and the workpiece set on the beside the machine. Plain radial drilling machines provide only for vertical movement of the spindle;universal machines allow the spindle to swivel about an axis normal to the radial armand the radial arm to rotate about a horizontal axis, thus permitting drilling at anyangle. A multispindle drilling machine has one or more heads that drive the spindlesthrough universal joints and telescoping splined shafts. All spindles are usually drivenby the same motor and fed simultaneously to drill the desired number of holes. Inmost machines each spindle is held in an adjustable plate so that it can be movedrelative to the others. The area covered by adjacent spindles overlap so that themachine can be set to drill holes at any location within its range. The milling operation involves metal removal with a rotating cutter. It includesremoval of metal from the surface of a workspiece, enlarging holes, and form cutting,such as threads and gear teeth. Within an knee and column type of milling machine the column is the mainsupporting member for the other components, and includes the base containing thedrive motor, the spindle, and the cutters. The cutter is mounted on an arbor held in thespindle, and supported on its outer extremity by a bearing in the overarm. The knee isheld on the column in dovetail slots, the saddle is fastened to the knee in dovetailslots, and the table is attached to the saddle. Thus, the build-up the knee and column2机械设计制造及自动化专业毕业设计（论文）外文翻译machine provides three motions relative to the cutter. A four motion may be providedby swiveling the table around a vertical axis provided on the saddle. Fixed-bed milling machines are designed to provide more rigidity than the kneeand column type. The table is mounted directly on the machine base, which providesthe rigidity necessary for absorbing heavy cutting load, and allows only longitudinalmotion to the table. Vertical motion is obtained by moving the entire cutting head. Tracer milling is characterized by coordinated or synchronized movements ofeither the paths of the cutter and tracing elements, or the paths of the workpiece andmodel. In a typical tracer mill the tracing finger follow the shape of the masterpattern, and the cutter heads duplicate the tracer motion. The following are general design considerations for milling: 1. Wherever possible, the part should be designed so that a maximum number ofsurfaces can be milled from one setting. 2. Design for the use of multiple cutters to mill several surfaces simultaneously. 3. The largest flat surface will be milled first, so that all dimensions are bestreferred to such surface. 4. Square inside corners are not possible, since the cutter rotates.Grinding Machines and Special Metal-removal ProcessRandom point-cutting tools include abrasives in the shape of a wheel, bonded to abelt, a stick, or simply suspended in liquid. The grinding process is of extremeimportance in production work for several reasons.1.It is most common method for cutting hardened tool steel or other heat-treatedsteel. Parts are first machined in the un-heat-treated condition, and then ground to thedesired dimensions and surface finish.2.It can provide surface finish to 0.5m without extreme cost.3.The grinding operation can assure accurate dimensions in a relatively shorttime, since machines are built to provide motions in increments of ten-thousandths ofan inch, instead of thousandths as is common in other machines. 4.Extremely small and thin parts can be finished by this method, since lightpressure is used and the tendency for the part to deflect away from the cutter isminimized.On a cylindrical grinding machine the grinding wheel rotates between 5500 and6500 rpm., while the work rotates between 60 and 125 rpm. The depth of cut is13机械设计制造及自动化专业毕业设计（论文）外文翻译controlled by moving the wheel head, which includes both the wheel and its drivemotor. Coolants are provided to reduce heat distortion and to remove chips andabrasive dust.Material removal from ductile materials can be accomplished by using a toolwhich is harder than the workpiece. However during Word War the widespread useof materials which were as hard or harder than cutting tools created a demand for newmaterial-removal methods. Since then a number of processes have been developedwhich, although relatively slow and costly, can effectively remove excess material ina precise and repeatable fashion. There are two types of processes. The first type isbased on electrical phenomena and is used primarily for hard materials; the seconddepends upon chemical dissolution. Chemical milling is controlled etching process using strong alkaline or acidetchants. Aluminum, titanium, magnesium, and steel are the principal metalsprocessed by this method. The area to remain untouched by the etchant are maskedwith a protective coating. For example, the entire part may be dipped in the maskingmaterial and the mask removed from those areas to be etched, or a chemicallyresistant prescribed time, after which the part is rinsed in cold water, the maskingremoved, the part inspected, and thoroughly cleaned.There are certain disadvantages to consider. Metal will erode equally in alldirections, so that walls of the etched section will have a radius equal to the depth ofetch. A second disadvantage is that a better finish is obtained on surfaces parallel tothe direction of rolling of a sheet than on surface perpendicular to the direction ofrolling. This can be compared to the surface obtained when working wood parallel to,or across the grain. A third disadvantage, not unique with this process, is the warpagethat will occur in thin, previously stressed sections etched on just one side.Chemical milling, however, has many advantages over conventional metal-removal methods. There is no warpage of heavy sections such as forgings orextrusions when the etchant is applied simultaneously to all sides for reduction ofsection thickness. In conventional milling only one side can be worked at a time, andfrequent turning of a part is necessary to prevent warpage. Chemical milling can beapplied to parts of irregular shape where conventional milling may be very difficult.Light-weight construction can be obtained with chemical milling by the elimination ofwelding, riveting, and stiffeners; parts can be contoured to distribute the load in themost suitable manner. As an example of the potential savings of this process, ascompared to machine milling, one company reports that the cost of removing14机械设计制造及自动化专业毕业设计（论文）外文翻译aluminum by chem.-milling is $0.27 per pound as compared to $1.00 per pound byconventional milling. The rate of metal removal for chem.-milling is 0.001in. foraluminum.Electric-discharge machining is a process in which an electrical potential isimpressed between the workpiece and the tool, and the current, emanating from apoint source on the workpoiece, flows to the tool in the form of a spark. The forcesthat accomplish the metal removal are within the workpiece proper and, as a result, itis not necessary to construct the unit to withstand the heavy pressures and loadsprevalent with conventional machining methods.The frequency of the electrical discharge ranges from 20,00 cps (cycles persecond) for rough machining, to 50,000 cps for finishing such items as hardened toolsand dies. The current may vary from 50 amp, during rough machining, to as low as0.5 amp, during finishing. The process is currently applied to the machining of single-point tools, form tools, milling cutters, broaches, and die cavities. It is also applicableto the removal of broken drills, taps, and studs without damaging the workpiece inwhich the broken tool is imbedded. Other uses are the machining of oil holes in ahardened part, and the machining of small safety-wire holes in the heads of specialalloy bolts, such as titanium.The ultrasonic machining process is applied to both conducting and non-conducting material, and relies entirely upon abrasive action for metal removal. Theworkpiece is submerged in slurry of finely fivided abrasive particles in a vehicle suchas water. The tool is coupled to an oscillator and vibrates at frequencies between15,000 and 30,000 cps. The vibrating tool cavitates the liquid, and the force drives theabrasive into the surface of the workpiece to remove metal chips which are carriedaway by the liquid. The acceleration given the abrasive grains is as much as 100,000times the acceleration of gravity, providing a smooth and rapid cutting force.Introduction of MachiningMachining as a shape-producing method is the most universally used and themost important of all manufacturing processes. Machining is a shape-producingprocess in which a power-driven device causes material to be removed in chip form.Most machining is done with equipment that supports both the work piece and cuttingtool although in some cases portable equipment is used with unsupported workpiece. Low setup cost for small quantities. Machining has tow applications in15机械设计制造及自动化专业毕业设计（论文）外文翻译manufacturing. For casting, forging, and pressworking, each specific shape to bep5roduced, even one part, nearly always has a high tooling cost. The shapes that maybe produced, even one part, nearly always has a high tooling cost. The shapes thatmay be produced by welding depend to a large degree on the shapes of raw materialthat are available. By making use of generally high cost equipment but without specialtooling, it is possible, bu machining, to start with nearly any form of any material, solong as the exterior dimensions are great enough, and produce any desired shape fromany material. Therefore, machining is usually the preferred method for producing oneor a few parts, even when the design of the part would logically lead to casting,forging or pressworking if a high quantity were to be produced.Close accuracies, good finishes. The second application for machining is based on thehigh accuracies and surface finishes possible. Many of the parts machined in lowquantities would be produced with lower but acceptable tolerances if produced in highquantities by some other process. On the other hand, many pars are given shapes bysome high quantity deformation process and machined only on selected surfaceswhere high accuracies are needed. Internal threads, for example, are seldom producedby any means other than machining and small holes in pressworked parts may bemachined following the pressworking operations.16机械设计制造及自动化专业毕业设计（论文）外文翻译 钻床和铣削钻床和铣削 直式钻床或钻孔式印刷机可用于各种尺寸和种类，它能安装轴速度的足够范围和自动运转以适应大多工业的要求。一个典型机器的速度范围是 70至2025rmp，以及钻孔的运转速度是0.002到 0.020英尺。 旋转钻床用来钻那些太大或太笨重的而不能够移动的工件。 通过将转臂绕立柱的转动和主轴组件沿转臂的移动组合，可使主轴钻头对准机床可达范围内的任何位置，由于运转太大而不方便建立在此基础上，主轴能够在垂直的地上方摇摆以及工件能固定在机器旁边的地上。 普通的旋臂钻床只提供轴的垂直运动和径向转臂，通过平行轴来运转。因此允许钻头处于任何一个角度。 一个多轴通过万能连接和可伸缩的花键轴来驱动的钻床有一个或多个头。 通常所有的轴都是通过相同的发动机来驱动和同时运转，目的是钻出理想中洞的数量。 很多钻床的每个轴容纳在一个可调整的盘里，以便与其他相关的部件移动。 相邻的轴重叠部分的覆盖区域目的促使机器能够在它的范围的任何地方开始钻孔。 铣床操作与转动的切削金属和移动相关。 它包括了一个工件的表面金属移动，洞的扩大和成型切削，比如线和齿轮。 铣销机床的升降台式柱是其他部件的主要支持部分。 包括了容量驱动机的基础，心轴切割工具。 切割工具固定在容纳在主轴的刀杆上能过一个悬臂的轴承支撑在它的外部的末端。 升降台通过燕尾槽滑动支撑立柱和立柱机器，提供一三种与切割工具相关的意向。 另一种意向可能是工作台由提供的滑板围绕着轴旋转而得到的。 固定的铣销机床的设计目的是比升降台或立柱提供更大的刚度。 工作台直接固定在机窗的根部，它能为强大切割负荷提供强度的需要。 而且允许对工作台径度的方向。垂直运动是通过移动整个切割工具才能达到。 仿型铣床的特点是刀具和跟踪元件的轨道运动的协调或同步，或者是工件或模型的轨迹运动的协调或同步典型的仿型铣床的仿型号像是遵照模型的形式，而且切割机头部分与仿行部分相同。下面是铣削的总体的设计目录：1.如果可能的话，零件将被设计以便在一个工位上最大的平面能被铣削。2.对选择性的切割工具的设计目的是同时铣削几个平面。17机械设计制造及自动化专业毕业设计（论文）外文翻译3.应当首先铣最大的平面，这样所有的尺寸都能很好的参照这个表面。4.因为切割工具的转动，仿形里的各个角落是不可能的。刺耳的机器和特殊的金属移动程序刺耳的机器和特殊的金属移动程序随机点切削刀具包括构成轮子形状的，或粘结到带子或棍子上或直接悬浮在液体中的研磨材料。因为几个原因研磨进程在工件的生产中很重要。对切削硬化的刀具钢材料或其他的热处理钢材来讲它是最普通的方法。 零件在没有热处理条件下第一次机器切割，然后得到理想的尺度和表面光洁度。它能在没有极限范畴时提供表面光洁度达0.5微米。研磨操作在相对较短的时间内能确保精确的尺度，因为机器在作为其它机器的一般精度构造时提供的动态是每英尺增加了百分之一的精度，而不是千分之一。尤其是小而细的零件能用这个方法完成，由于轻压力被使用和零件的柔韧性所折射出的切削值是最小的。研磨轮子在圆柱形的研磨机器上在 5500 和 6500rmp之间转动，当工件在 60和 125rmp之间转动时，切削的深度运动由木头控制，它包括了轮子和它的驱动发动机。冷却液用来降低热扭曲和移动切削以及研磨材料时的灰尘。有韧性的材料的运动通过那些材质硬的刀具来完成，但是在二战期间材料的广泛传播使用，它比新材料运动方法的切削刀具的要求更高。 因为大量的过程被改进，尽管相当慢且花费高，它能用精确接受的方式来移动过量的材料，这里有两种进程模式：第一种类型是建立在电子现象的基础上，它用于基本的原材料；第二种取决于化学溶解。化学物质的铣削用于控制那些用了很浓的碱性或酸性的腐蚀剂腐蚀进程。 铝钛、镁和钢是通过这种方式的主要原料进程。化学铣削开始于一个零件的传统的光洁，包括脱脂、 脱酸和烘干，这个领域用以维持不与那些笼罩在制服外面的腐蚀剂接触。 可以将整个零件侵入遮盖材料，然后将遮盖层从将要被侵蚀的区域去除；也可以使用抗化学侵蚀的粘接带遮盖要保护的区域，遮盖之后要侵蚀一般指定的时间，然后要将零件在冷水中清洗，将遮盖层去除，检查零件，并彻底全面的清洗。还应该考虑到的缺点：第一缺点是金属在各个方面都是平等的侵蚀，以至于侵蚀的外部半径和侵蚀的深度相等；第二个缺点是在平行于钢板的方向上所得光洁度要比垂直于木纹的方向上工作所得的表面相比较；第三个缺点不是过18机械设计制造及自动化专业毕业设计（论文）外文翻译程的唯一，而是发生在细的只腐蚀一边的压力段上的翘曲。而化学铣削在传统的金属移动方发中有很多的优点。 这在很多部件没有翘曲例如当腐蚀被用来降低纵切面厚度的各个面上时的锻造和挤压，传统的铣削里一次只用一面来运转，而且零件的频繁转变是阻止翘曲所必要的。 化学铣削能用于不规则的部件，而那是传统铣削很难做到的。 轻易的建筑物可通过焊接的清除铆接和加强筋与铣削而获得零件可以被定形通过以适当的方式分配负荷和潜在的节省过程的例子一样，与机器切割铣床相比。 一个文件报道了有关化学铣削移动铝的成本，是0.27美元每英镑，而传统铣削则是1.00 美元每英镑。所以铣削铝金属移动的比率是0.001英尺每分钟。电子排放机器是一个电压作用于工件和刀具之间的过程，电流从金属工件的源头流出，以火花的形式流向刀具。完成金属移动的力量是金属工件本身。结果，对一般的传统机械手段而言，没有必要建设一个单元来抵制重压和重负荷。由于排放器的范围大约从2000cps至5000cps 用来精加工如此硬的刀具和模具。电流在粗加工期间是不断变化的。 从 50amp低到精加工期间的0.5amp，这个过程应用了机械的单点刀具，成形刀具，铣削切割刀具，拉刀以及模具涡凹。 它也能移动坏了的钻头，而丝锥和螺栓不损坏嵌入的工件。 其他的使用方法是一个硬部件的油洞，小安全电线洞的机械是由大量特殊合金制造的，如钛。超声机械程序用于导体和半导体，而且完全依靠于金属移动的研磨行为，工件淹没在液下分数的研磨微粒如水。刀具连接着震荡器以及在 15000 至3000cps 之间频繁的震动，震动的刀具抽空液体，冲力研磨材料进入工件的表面用来移动金属切削。 它们能随着液体流动。 研磨的纹密加速度是重力的100000倍，以提供一个光滑而快速的切削冲力。 关于机械加工关于机械加工作为一种成形方式的机械加工是广泛使用的也是所有机械制造进程中的最重要的部分。 机械加工是通过切削形式使驱动装置引起材料运动产生形状的过程尽管在某些场合，工作支持情况下，使用移动式装备实现加工，但是大多数的机械加工还是通过既支撑工件有支撑刀具的装备来完成。小批量生产低费用，机械加工在制造方面有两种用途：对浇筑，锻造，压力加工，即将生产的每个具体形状，甚至一个零件而言，几乎是一个高标准的刀具铸型。 这些通过焊接可能产生的形状在很大程度上取决可利用的原材料的形状。 一般说来，通过利用高价设备而又无需特种加工条件下，几乎可以从任何种类原材料开始，借助机械加工把原材料加工成任意要求的结构形状，只要外部尺寸够大，那都是可能的。 因此，机械加工是常用来生产少量零件，甚至在大量生产以及当零件的设计在逻辑上导致浇铸、 锻造，压力加工的时候所推荐的方法严密的精度，合适的平面粗糙度，对机械加工的第二个应用是建立在可行性的高精度和高表面粗糙度之上。 很多用机械切割的少量部件会产生较小且能够19机械设计制造及自动化专业毕业设计（论文）外文翻译接受的偏差是否能够通过其他的工艺流程生产大量的部件。 另一方面，很多部件通过一些大量的变形过程和由机械切割所需要的高精度选择平面有了他们的一般形状，例如：内部的螺纹很少能通过其他的方式生产，除了机械加工和压力加工部件的小洞可能被机器切割成的压力加工过的操作。附录二附录二 LATHES & MILLINGA shop that is equipped with a milling machine and an engine lathe can machinealmost any type of product of suitable size.The basic machines that are designed primarily to do turning，facing and boringare called lathes. Very little turning is done on other types of machine tools，andnone can do it with equal facility. Because lathe can do110机械设计制造及自动化专业毕业设计（论文）外文翻译boring ，facing，drilling ，and reaming in addition to turning ，their versatilitypermits several operations to be performed with a single setup of the workpiece. Thisaccounts for the fact that lathes of various types are more widely used inmanufacturing than any other machine tool. Lathes in various forms have existed for more than two thousand years. Modernlathes date from about 1797，when Henry Maudsley developed one with a leadscrew. It provided controlled ， mechanical feed of the tool. This ingeniousEnglishman also developed a change gear system that could connect the motions ofthe spindle and leadscrew and thus enable threads to be cut. Lathe Construction. The essential components of a lathe are depicted in theblock diagram of picture. These are the bed ， headstock assembly ， tailstockassembly，carriage assembly，quick-change gearbox，and the leadscrew and feedrod. The bed is the back bone of a lathe. It usually is made of well-normalized oraged gray or nodular cast iron and provides a heavy，rigid frame on which all theother basic components are mounted. Two sets of parallel，longitudinal ways，innerand outer，are contained on the bed，usually on the upper side. Some makers use aninverted V-shape for all four ways，whereas others utilize one inverted V and one flatway in one or both sets. Because several other components are mounted and/or moveon the ways they must be made with precision to assure accuracy of alignment.Similarly，proper precaution should betaken in operating a lathe to assure that theways are not damaged. Any inaccuracy in them usually means that the accuracy of theentire lathe is destroyed. The ways on most modern lathes are surface hardened tooffer greater resistance to wear and abrasion. The headstock is mounted in a fixed position on the inner ways at one end of thelathe bed. It provides a powered means of rotating the work at various speeds. Itconsists，essentially，of a hollow spindle，mounted in accurate bearings，and a setof transmission gearssimilar to a truck transmissionthrough which thespindle can be rotated at a number of speeds. Most lathes provide from eight to111机械设计制造及自动化专业毕业设计（论文）外文翻译eighteen speeds，usually in a geometric ratio，and on modern lathes all the speedscan be obtained merely by moving from two to four levers. An increasing trend is toprovide a continuously variable speed range through electrical or mechanical drives. Because the accuracy of a lathe is greatly dependent on the spindle，it is ofheavy construction and mounted in heavy bearings，usually preloaded tapered rolleror ball types. A long- itudinal hole extends through the spindle so that long bar stock can be fedthrough it. The size of this hole is an important size dimension of a lathe because itdetermines the maximum size of bar stock that can be machined when the materialmust be fed through the spindle. The inner end of the spindle protrudes from the gear box and contains a meansfor mounting various types of chucks，face plates，and dog plates on it. Whereassmall lathes often employ a threaded section to which the chucks are screwed，mostlarge lathes utilize either cam-lock or key-drive taper noses. These provide a large-diameter taper that assures the accurate alignment of the chuck，and a mechanismthat permits the chuck or face plate to be locked or unlocked in position without thenecessity of having to rotate these heavy attachments.Power is supplied to the spindle by means of an electric motor through a V-beltor silent-chain drive. Most modern lathes have motors of from 5 to15 horsepower toprovide adequate power for carbide and ceramic tools at their high cutting speeds.The tailstock assembly consists，essentially，of three parts. A lower casting fitson the inner ways of the bed and can slide longitudinally thereon，with a means forclamping the entire assembly in any desired location. An upper casting fits on thelower one and can be moved transversely upon it on some type of keyed ways. Thistransverse motion permits aligning the tailstock and headstock spindles and provides amethod of turning tapers. The third major component of the assembly is the tailstockquill. This is a hollow steel cylinder，usually about2 to3 inches in diameter，that canbe moved several inches longitudinally in and out of the upper casting by means of ahand wheel and screw. The open end of the quill hole terminates in a Morse taper in112机械设计制造及自动化专业毕业设计（论文）外文翻译which a lathe center ，or various tools such as drills ，can be held. A graduatedscale，several inches in length，usually is engraved on the outside of the quill to aidin controlling its motion in and out of the upper casting. A locking device permitsclamping the quill in any desired position. The carriage assembly provides the means for mounting and moving cuttingtools. The carriage is a relatively flat H-shaped casting that rests and moves on theouter set of ways on the bed. The transverse bar of the carriage contains ways onwhich the cross slide is mounted and can be moved by means of a feed screw that iscontrolled by a small hand wheel and a graduated dial. Through the cross slide ameans is provided for moving the lathe tool in the direction normal to the axis ofrotation of the work.On most lathes the tool post actually is mounted on a compound rest. Thisconsists of abase，which is mounted on the cross slide so that it can be pivoted abouta vertical axis，and an upper casting. The upper casting is mounted on ways on thisbase so that it can be moved back and forth and controlled by means of a short leadscrew operated by a hand wheel and a calibrated dial. Manual and powered motion for the carriage，and powered motion for thecross slide，is provided by mechanisms within the apron，attached to the front of thecarriage. Manual movement of the carriage along the bed is effected by turning a handwheel on the front of the apron，which is geared to a pinion on the back side. Thispinion engages a rack that is attached beneath the upper front edge of the bed in aninverted position.To impart powered movement to the carriage and cross slide，a rotating feed rodis provided. The feed rod ， which contains a keyway through out most of itslength，passes through the two reversing bevel pinions and is keyed to them . Eitherpinion cam be brought into mesh with a mating bevel gear by means of the reversing lever on the front of the apron andthus provide “forward” or “reverse” power to the carriage. Suitable clutches connecteither the rack pinion or 113机械设计制造及自动化专业毕业设计（论文）外文翻译the cross-slide screw to provide longitudinal motion of the carriage or transversemotion of cross slide.For cutting threads，a second means of longitudinal drive is provided by a leadscrew. Whereas motion of the carriage when driven by the feed-rod mechanism takesplace through a friction clutch in which slippage is possible，motion through the leadscrew is by a direct，mechanical connection between the apron and the lead screw.This is achieved by a split nut. By means of a clamping lever on the front of theapron ， the split nut can be closed around the lead screw. With the split nutclosed，the carriage is moved along the lead screw by direct drive without possibilityof slippage.Modern lathes have a quick-change gear box. The input end of this gearbox isdriven from the lathe spindle by means of suitable gearing. The out put end of thegear box is connected to the feed rod and lead screw. Thus ， through this geartrain，leading from the spindle to the quick-change gearbox，thence to the leadscrew and feed rod，and then to the carriage，the cutting tool can be made to move aspecific distance，either longitudinally or transversely，for each revolution of thespindle. A typical lathe provides，through the feed rod，forty-eight feeds rangingfrom 0.002 inch to0.118 inch per revolution of the spindle，and，through the leadscrew，leads for cutting forty-eight different threads from 1.5 to 92perinch.On someolder and some cheaper lathes，one or two gears in the gear train between the spindleand the change gear box must be changed in order to obtain a full range of threads andfeeds.Milling is a basic machining process in which the surface is generated by theprogressive formation and removal of chips of material from the workpiece as it is fedto a rotating cutter in a direction perpendicular to the axis of the cutter. .In some casesthe workpiece is stationary and the cutter is fed to the work. In most instances amultiple-tooth cutter is used so that the metal removal rate is high，and frequently thedesired surface is obtained in a single pass of the work.The tool used in milling is known as a milling cutter. It usually consists of a114机械设计制造及自动化专业毕业设计（论文）外文翻译cylindrical body which rotates on its axis and contains equally spaced peripheral teeththat intermittently engage and cut the workpiece. In some cases the teeth extend partway across one or both ends of the cylinder. Because the milling principle provides rapid metal removal and can producegood surface finish，it is particularly well-suited for mass-production work，andexcellent milling machines have been developed for this purpose. However ，veryaccurate and versatile milling machines of a general-purpose nature also have beendeveloped that are widely used in job-shop and tool and die work. A shop that isequipped with a milling machine and an engine lathe can machine almost any type ofproduct of suitable size.Types of Milling Operations. Milling operations can be classified into two broadcategories，each of which has several variations：1.In peripheral milling a surface is generated by teeth located in the periphery ofthe cutter body；the surface is parallel with the axis of rotation of the cutter. Both flatand formed surfaces can be produced by this method. The cross section of theresulting surface corresponds to the axial contour of the cutter. This procedure often iscalled slab milling.1.In face milling the generated flat surface is at right angles to the cutteraxis and is the combined result of the actions of the portions of the teeth located on both theperiphery and the with the face portions providing a finishing action.The basic concepts of peripheral and face milling are illustrated in Fig.Peripheral milling operations usually are performed on machines having horizontalspindles ， whereas face milling is done on both horizontal-and vertical-spindlemachines.Surface Generation in Milling. Surfaces can be generated in milling by twodistinctly different methods depicted in Fig. Note that in up milling the cutter rotatesagainst the direction of feed the workpiece，whereas in down milling the rotation isin the same direction as the feed .As shown in Fig., the method of chip formation is115机械设计制造及自动化专业毕业设计（论文）外文翻译quite different in the two cases. In up milling the c hip is very thin at the beginning,where the tooth first contacts the work ，and increases in thickness, be-coming amaximum where the tooth leaves the work. The cutter tends to push the work alongand lift it upward from the table. This action tends to eliminate any effect of loosenessin the feed screw and nut of the milling machine table and results in a smooth cut.However, the action also tends to loosen the work from the clamping device so thatgreater clamping forcers must be employed. In addition, the smoothness of thegenerated surface depends greatly on the sharpness of the cutting edges.In down milling，maximum chip thickness occurs close to the point at which thetooth contacts the work. Because the relative motion tends to pull the workpiece intothe cutter，all possibility of looseness in the table feed screw must be eliminated ifdown milling is to be used. It should never be attempted on machines that are notdesigned for this type of milling. In as mush as the material yields in approximately atangential direction at the end of the tooth engagement，there is much less tendencyfor the machined surface to show tooth marks than when up milling is used. Anotherconsider able advantage of down milling is that the cutting force tends to hold thework against the machine table，permitting lower clamping force to be employed.This is particularly advantageous when milling thin workpiece or when taking heavycuts.Sometimes a disadvantage of down milling is that the cutter teeth strike againstthe surface of the work at the beginning of each chip. When the workpiece has a hardsurface，such as castings do，this may cause the teeth to dull rapidly.Milling Cutters. Milling cutters can be classified several ways. One method is togroup them into two broad classes，based on tooth relief，as follows：1. Profile-cutters have relief provided on each tooth by grinding a small landback of the cutting edge. The cutting edge may be straight or curved.2.In form or cam-relieved cutters the cross section of each tooth is an eccentriccurve behind the cutting edge，thus providing relief. All sections of the eccentricrelief，parallel with the cutting edge，must have the same contour as the cutting116机械设计制造及自动化专业毕业设计（论文）外文翻译edge. Cutters of this type are sharpened by grinding only the face of the teeth，withthe contour of the cutting edge thus remaining unchanged. Another useful method of classification is according to the method of mountingthe cutter. Arbor cutters are those that have a center hole so they can be mounted onan arbor. Shank cutters have either tapered or straight integral shank. Those withtapered shanks can be mounted directly in the milling machine spindle ，whereasstraight-shank cutters are held in a chuck. Facing cutters usually are bolted to the end of a stub arbor.Types of Milling Cutters. Plain millingcutters are cylindrical or disk-shaped ， having straight or helical teeth on theperiphery. They are used for milling flat surfaces. This type of operation is calledplain or slab milling. Each tooth in a helical cutter engages the work gradually，andusually more than one tooth cuts at a given time. This reduces shock and chatteringtendencies and promotes a smoother surface. Consequently ， this type of cutterusually is preferred over one with straight teeth. Side milling cutters are similar toplain milling cutters except that the teeth extend radially part way across one or bothends of the cylinder toward the center. The teeth may be either straight or helical.Frequently these cutters are relatively narrow，being disklike in shape. Two or moreside milling cutters often are spaced on an arbor to make simultaneous ，parallelcuts，in an operation called straddle milling. Interlocking slotting cutters consist of two cutters similar to side mills ，butmade to operate as a unit for milling slots. The two cutters are adjusted to the desiredwidth by inserting shims between them. Staggered-tooth milling cutters are narrow cylindrical cutters having staggeredteeth，and with alternate teeth having opposite helix angles. They are ground to cutonly on the periphery ， but each tooth also has chip clearance ground on theprotruding side. These cutters have a free cutting action that makes them particularlyeffective in milling deep slots. Metal-slitting saws are thin ， plain millingcutters ， usually from 1/32 to 3/16 inch thick ， which have their sidesslightly“dished”to provide clearance and prevent binding. They usually have more117机械设计制造及自动化专业毕业设计（论文）外文翻译teeth per inch of diameter than ordinary plain milling cutters and are used for millingdeep，narrow slots and for cutting-off operations.118机械设计制造及自动化专业毕业设计（论文）外文翻译附录附录2 车床和铣床车床和铣床车间里拥有一台车床和一台普通铣床就能加工出具有适合尺寸的各种产品。用于车外圆、端面和镗孔等加工的机床称作车床。车削很少在其他种类的机床上进行，因为其他机床都不能像车床那样方便地进行车削加工。 由于车床除了用于车外圆外还能用于镗孔、车端面、钻孔和铰孔，车床的多功能性可以使工件在一次定位安装中完成多种加工。 这就是在生产中普遍使用各种车床比其他种类的机床都要多的原因。两千多年前就已经有了车床。现代车床可以追溯到大约1797 年，那时亨利莫德斯利发明了一种具有丝杠的车床。这种车床可以控制工具的机械进给。 这位聪明的英国人还发明了一种把主轴和丝杠相连接的变速装置这样就可以切削螺纹。 图中标出了车床的主要部件：床身、 主轴箱组件、 尾架组件拖板组件、 变速齿轮箱、 丝杠和光杠。 床身是车床的基础件。 它通常是由经过充分正火或时效处理的灰铸铁或者球墨铸铁制成，它是一个坚固的刚性框架，所有其他主要部件都安装在床身上。通常在床身上面有内外两组平行的导轨。一些制造厂生产的四个条导轨都采用倒“V ”形，而另一些制造厂则将倒“ V ”形导轨和平面导轨相结合。 由于其他的部件要安装在导轨上并（或）在导轨上移动，导轨要经过精密加工，以保证其装配精度。 同样地，在操作中应该小心，以避免损伤导轨。导轨上的任何误差，常常会使整个机床的精度遭到破坏。大多数现代车床的导轨要进行表面淬火处理，以减小磨损和擦伤，具有更大的耐磨性。 主轴箱安装在床身一端内导轨的固定位置上。它提供动力，使工件在各种速度下旋转。它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮类似于卡车变速箱所组成，通过变速齿轮，主轴可以在许多种转速下旋转。 大多数车床有 8-18 种转速，一般按等比级数排列。在现代车床上只需扳动 2-4 个手柄，就能得到全部挡位的转速。 目前发展的趋势是通过电气的或机械的装置进行无级变速。 由于车床的精度在很大程度上取决于主轴，因此主轴的结构尺寸较大，通常安装在紧密配合的重型圆锥滚子轴承或球轴承中。 主轴中有一个贯穿全长的通孔，长棒料可以通过该孔送料。 主轴孔的大小是车床的一个重要尺寸，因为当工件必须通过主轴孔供料时，它确定了能够加工棒料毛坯的最大外径尺寸。主轴的内端从主轴箱中凸出，其上可以安装多种卡盘、花盘和挡块。而小型1