关于机械加工钻床和铣削课程毕业设计外文文献翻译@中英文翻译@外文翻译

中国地质大学长城学院本科毕业设计外文资料翻译系 别： 工程技术系 专 业： 机械设计制造及其自动化 姓 名： 王硕 学 号： 05211611 2015年 4 月 4 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 MachinesUpright drilling machines or drill presses are available in a variety of sizes and types, and are equipped with a sufficient range of apindle speeds and automatic feeds to fit the neds of most industries. Speed ranges on a typical machine are from 76 to 2025 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 or cumbersome to conveniently move. The spindle with the speed and feed changing mechanism is mounted on the radial arm; by combining the movement of the radial arm around column and the movement of the spindle assembly along the arm, it is possible 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 assembly can 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 arm and the radial arm to rotate about a horizontal axis, thus permitting drilling at any angle.A multispindle drilling machine has one or more heads that drive the spindles through universal joints and telescoping splined shafts. All spindles are usually driven by the same motor and fed simultaneously to drill the desired number of holes. In most machines each spindle is held in an adjustable plate so that it can be moved relative to the others. The area covered by adjacent spindles overlap so that the machine can be set to drill holes at any location within its range.The milling operation involves metal removal with a rotating cutter. It includes removal 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 main supporting member for the other components, and includes the base containing the drive motor, the spindle, and the cutters. The cutter is mounted on an arbor held in the spindle, and supported on its outer extremity by a bearing in the overarm. The knee is held on the column in dovetail slots, the saddle is fastened to the knee in dovetail slots, and the table is attached to the saddle. Thus, the build-up the knee and column 2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 provided by swiveling the table around a vertical axis provided on the saddle.Fixed-bed milling machines are designed to provide more rigidity than the knee and column type. The table is mounted directly on the machine base, which provides the rigidity necessary for absorbing heavy cutting load, and allows only longitudinal motion to the table. Vertical motion is obtained by moving the entire cutting head.Tracer milling is characterized by coordinated or synchronized movements of either the paths of the cutter and tracing elements, or the paths of the workpiece and model. In a typical tracer mill the tracing finger follow the shape of the master pattern, 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 of surfaces 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 best referred 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 a belt, a stick, or simply suspended in liquid. The grinding process is of extreme importance in production work for several reasons.1.It is most common method for cutting hardened tool steel or other heat-treated steel. Parts are first machined in the un-heat-treated condition, and then ground to the desired 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 short time, since machines are built to provide motions in increments of ten-thousandths of an inch, instead of thousandths as is common in other machines. 4.Extremely small and thin parts can be finished by this method, since light pressure is used and the tendency for the part to deflect away from the cutter is minimized.On a cylindrical grinding machine the grinding wheel rotates between 5500 and 6500 rpm., while the work rotates between 60 and 125 rpm. The depth of cut is 13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 drive motor. Coolants are provided to reduce heat distortion and to remove chips and abrasive dust.Material removal from ductile materials can be accomplished by using a tool which is harder than the workpiece. However during Word War the widespread use of materials which were as hard or harder than cutting tools created a demand for new material-removal methods. Since then a number of processes have been developed which, although relatively slow and costly, can effectively remove excess material in a precise and repeatable fashion. There are two types of processes. The first type is based on electrical phenomena and is used primarily for hard materials; the second depends upon chemical dissolution. Chemical milling is controlled etching process using strong alkaline or acid etchants. Aluminum, titanium, magnesium, and steel are the principal metals processed by this method. The area to remain untouched by the etchant are masked with a protective coating. For example, the entire part may be dipped in the masking material and the mask removed from those areas to be etched, or a chemically resistant prescribed time, after which the part is rinsed in cold water, the masking removed, the part inspected, and thoroughly cleaned.There are certain disadvantages to consider. Metal will erode equally in all directions, so that walls of the etched section will have a radius equal to the depth of etch. A second disadvantage is that a better finish is obtained on surfaces parallel to the direction of rolling of a sheet than on surface perpendicular to the direction of rolling. 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 warpage that 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 or extrusions when the etchant is applied simultaneously to all sides for reduction of section thickness. In conventional milling only one side can be worked at a time, and frequent turning of a part is necessary to prevent warpage. Chemical milling can be applied to parts of irregular shape where conventional milling may be very difficult. Light-weight construction can be obtained with chemical milling by the elimination of welding, riveting, and stiffeners; parts can be contoured to distribute the load in the most suitable manner. As an example of the potential savings of this process, as compared to machine milling, one company reports that the cost of removing 14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 by conventional milling. The rate of metal removal for chem.-milling is 0.001in. for aluminum.Electric-discharge machining is a process in which an electrical potential is impressed between the workpiece and the tool, and the current, emanating from a point source on the workpoiece, flows to the tool in the form of a spark. The forces that accomplish the metal removal are within the workpiece proper and, as a result, it is not necessary to construct the unit to withstand the heavy pressures and loads prevalent with conventional machining methods.The frequency of the electrical discharge ranges from 20,00 cps (cycles per second) for rough machining, to 50,000 cps for finishing such items as hardened tools and dies. The current may vary from 50 amp, during rough machining, to as low as 0.5 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 applicable to the removal of broken drills, taps, and studs without damaging the workpiece in which the broken tool is imbedded. Other uses are the machining of oil holes in a hardened part, and the machining of small safety-wire holes in the heads of special alloy 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. The workpiece is submerged in slurry of finely fivided abrasive particles in a vehicle such as water. The tool is coupled to an oscillator and vibrates at frequencies between 15,000 and 30,000 cps. The vibrating tool cavitates the liquid, and the force drives the abrasive into the surface of the workpiece to remove metal chips which are carried away by the liquid. The acceleration given the abrasive grains is as much as 100,000 times 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 the most important of all manufacturing processes. Machining is a shape-producing process 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 cutting tool although in some cases portable equipment is used with unsupported workpiece. Low setup cost for small quantities. Machining has tow applications in 15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 be p5roduced, even one part, nearly always has a high tooling cost. The shapes that may be produced, even one part, nearly always has a high tooling cost. The shapes that may be produced by welding depend to a large degree on the shapes of raw material that are available. By making use of generally high cost equipment but without special tooling, it is possible, bu machining, to start with nearly any form of any material, so long as the exterior dimensions are great enough, and produce any desired shape from any material. Therefore, machining is usually the preferred method for producing one or 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 the high accuracies and surface finishes possible. Many of the parts machined in low quantities would be produced with lower but acceptable tolerances if produced in high quantities by some other process. On the other hand, many pars are given shapes by some high quantity deformation process and machined only on selected surfaces where high accuracies are needed. Internal threads, for example, are seldom produced by any means other than machining and small holes in pressworked parts may be machined 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 轴来运转。此 钻头 于任何一个 度。一个多轴通过 能 和可 的 轴来 动的钻床 一个或多个头。通 的轴 是通过 的 动机来 动和 运转， 的是钻 的 。 多钻床的 个轴在一个可的，以便currency1 “的件移动。 的轴重fi的fl 的使机器能够在它的范围的任何地方钻孔。床转动的”和移动 “。它 一个工件的 移动， 的大和型”，和。 机床的 式柱是currency1件的主要fi。 动机的基础，轴工 。工 固定在在主轴的 上能过一个 臂的轴 在它的外的 。 通过 动 立柱和立柱机器，提供一种工 “的 向。 一种 向可能是工 由提供的 围绕 轴旋转而到的。固定的 机床的设计 的是 或立柱提供 大的 度。工 直 固定在机 的 ，它能大提供度的 要。而 对工径度的方向。垂直运动是通过移动个工 能达到。型床的 是 和 件的 运动的 或 ，或是工件或型的运动的 或 典型的 型床的 型 是 型的形式，而 机头fi fi 。下是”的总体的设计 录：1.果可能的话，零件将被设计以便在一个工位上最大的 能被”。2.对选择性的工 的设计 的是 ”几个 。17机械设计制造及自动化专业毕业设计（论文）外文翻译3.应当首先最大的 ，这样 的尺寸 能 好的参 这个 。4. 工 的转动， 形的各个 落是不可能的。刺耳的机器和特殊的金属移动程序随机” 构子形状的，或粘结到带子或棍子上或直 浮在液体 的研磨材料。 几个原 研磨进程在工件的生产 重要。对”硬化的 钢材料或currency1的热 钢材来讲它是最普通的方法。零件在没 热 条件下第一次机器，然后到 的尺度和 光洁度。它能在没 极限范畴 提供 光洁度达0.5微米。研磨在 对较短的 间内能确保精确的尺度， 机器在currency1它机器的一般精度构造 提供的动态是 英尺增加百fi之一的精度，而不是千fi之一。尤currency1是小而细的零件能用这个方法完，由于轻压力被使用和零件的柔韧性 折射 的”值是最小的。研磨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 ，”的深度运动由木头控制，它 子和它的 动动机。冷却液用来低热扭曲和移动”以及研磨材料 的灰尘。韧性的材料的运动通过那些材质硬的 来完，但是在二战期间材料的广泛传播使用，它新材料运动方法的” 的要求 高。 大 的过程被改进，尽管 当慢 费高，它能用精确 受的方式来移动过 的材料，这 两种进程式：第一种类型是建立在