牛头刨床、钻床和铣削机床夹具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： 路双铭 学 号： 05211623 2015 年 4 月 1 日 Shapers, Drilling and Milling Machines A shapers utilizes a single-point tool on a tool holder mounted on the end of the ram. Cutting is generally done on the forward stroke. The tool is lifted slightly by the clapper box to prevent excessive drag across the work, which is fed under the tool during the return stroke in preparation for the next cut. The column houses the operating mechanisms of the shaper and also serves as a mounting unit for the work-supporting table. The table can be moved in two directions mutually perpendicular to the ram. The tool slide is used to control the depth of cut and is manually fed. It can be rotated through 90 deg, on either side of its normal vertical position, which allows feeding the tool at an angle to the surface of the table. Two types of driving mechanisms for shapers are a modified Whitworth quick-return mechanism and a hydraulic drive. For the Whitworth mechanism, the motor drives the bull gear, which drives a crank arm with an adjustable crank pin to control the length of stroke. As the bull gear rotates, the rocker arm is forced to reciprocate, imparting this motion to the shaper ram. The motor on a hydraulic shaper is used only to drive the hydraulic pump. The remainder of the shaper motions are controlled by the direction of the flow of the hydraulic oil. The cutting stroke of the mechanically driven shaper uses 220 deg. Of rotation of the bull gear, while the return stroke uses 140 deg. This gives a cutting stroke to return stroke ratio of 1.6 to 1. The velocity diagram for a hydraulic shaper shows that for most of the tool during cutting stroke is never constant, while the velocity diagram for a hydraulic shaper shows that for most of the cutting stroke the cutting speed is constant. The hydraulic shaper has an added advantage of infinitely variable cutting speeds. The principal disadvantage of this type of machine is the lack of a definite limit at the end of the ram stroke, which may allow a few thousandths of an inch variation in stroke length. A duplicating device that makes possible the reproduction of contours from a sheet-metal template is available. The sheet metal template is used in conjunction with hydraulic control. Upright 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 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 Process Random 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 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 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 Machining Machining 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 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. 牛头刨床、钻床和铣削 刨床是刀具特有者利用单点刀具将其安装在滑头的末梢。一般在做切削时都会向前冲程 .刀具被摆动刀架稍微举起，以避免（刀具）划过工件时产生严重的拖刮。它通过刀具在返回冲程期间运转并为下次的切割做准备。立柱被装有刨床的操作机械系统以及作为一个固定的单元为辅助点提供服务，工作台移动的两个方向是与滑块相互垂直的。刀具的滑行是用来控制切削的深度以及手动式地运转。它能在它的正常垂直方向的每一边上旋转 90 度。它允许在工作台表面的某个角落来运动刀具。 刨床 的两种驱动系统是一个改善的 whitworth 快速返回机械系统和一个液压驱动器。对于 whitworth 机械系统来讲，是发动机驱动大型的齿轮，它能通过控制可调整的曲柄驱动曲柄转臂来控制冲程的长度。对于大型的齿轮转动。摇动式的曲柄转臂被迫沿直线往复移动。增强了刨床滑枕的动向。 液压刨床发动机只用来驱动液压泵。刨床动向的提醒物被水硬油的流量方向所控制。机械驱动刨床的切削行程用了大齿轮转动的 220 度，返回行程用了 140度，这就使切削行程与返回行程之速比为 1.6:1 速度图显示了切削行程的大部分切削速度是连续不断 的。液压刨床是无穷变化的切削速度限制的缺乏，它可以允许在行程长度中有一些少量的变化。 可能产生与薄形钢板样板外型复制品的完全相同的装置是可利用的。薄型钢板的样板用来连接液压控制器。 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。 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 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。 1. 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。 2. 它能在没有极限范畴时提供表面光洁度达 0.5 微米。 3. 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 。 4. 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