1、毕业设计（论文） 外文翻译（原文） Lathe 来源： http:/en.wikipedia.org/wiki/Lathe A lathe is a machine tool which spins a block of material to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about
2、 an axis of rotation. Lathes are used in woodturning, metalworking, and glassworking. Lathes can be used to shape pottery, the best-known design being the potters wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads
3、 or helices. Ornamental lathes can produce three-dimensional solids of incredible complexity. The material is held in place by either one or two centers, at least one of which can be moved horizontally to accommodate varying material lengths. Examples of objects that can be produced on a lathe inclu
4、de cue sticks, table legs, bowls, baseball bats, crankshafts and camshafts. History The lathe is an ancient tool, dating at least to the Egyptians ， and known and used in Greece, the Roman and Byzantine Empires. The origin of turning dates to around 1300BC when the Egyptians first developed a two-pe
5、rson lathe. One person would turn the wood workpiece with a rope while the other used a sharp tool to cut shapes in the wood. The Romans improved the Egyptian design with the addition of a turning bow. Early bow lathes were also developed and used in Germany, France and Britain. In the Middle Ages a
6、 pedal replaced hand-operated turning, freeing both the craftsmans hands to hold the woodturning tools. The pedal was usually connected to a pole, often a straight-grained sapling. The system today is called the spring pole lathe. Spring pole lathes were in common use into the early 20th Century. A
7、two-person lathe, called a great lathe, allowed a piece to turn continuously (like todays power lathes). A master would cut the wood while an apprentice turned the crank。 During the industrial revolution the lathe was motorized, allowing wooden turned items to be created in less time and allowing th
8、e working of metal on a lathe. The motor also produced a greater rotational speed, making it easier to quickly produce high quality work. Today most commercial lathes are computer-operated allowing for mass-production that can be created with accurate precision and without the cost of employing craf
9、tsmen. Description Parts of a lathe A lathe may or may not have a stand, which sits on the floor and elevates the lathe bed to a working height. Some lathes are small and sit on a workbench or table, and do not have a stand. Almost all lathes have a bed, which is (almost always) a horizontal beam (a
10、lthough some CNC lathes have a vertical beam for a bed to ensure that swarf, or chips, falls free of the bed). A notable exception is the Hegner VB36 Master Bowlturner, a lathe designed for turning large bowls, which in its basic configuration is little more than a very large headst At one end of th
11、e bed (almost always the left, as the operator faces the lathe) is a headstock. The headstock contains high-precision spinning bearings. Rotating within the bearings is a horizontal axle, with an axis parallel to the bed, called the spindle. Spindles are often hollow, and have exterior threads and a
12、n interior taper on the inboard by which accessories which hold the workpiece may be mounted to the spindle. Spindles may also have exterior threads and an interior taper at their outboard end, or may have a handwheel or other accessory mechanism on their outboard end. Spindles are powered, and impa
13、rt motion to the workpiece. The spindle is driven, either by foot power from a treadle and flywheel or by a belt drive to a power source. In some modern lathes this power source is an integral electric motor. Accessories Unless a workpiece has a taper machined onto it which perfectly matches the int
14、ernal taper in the spindle, or has threads which perfectly match the external threads on the spindle (two things which almost never happen), an accessory must be used to mount a workpiece to the spindle. A workpiece may be bolted or screwed to a faceplate, a large flat disk that m A workpiece may be
15、 clamped in a chuck, which mounts directly to the spindle or mounted on a mandrel. In precision work (and in some classes of repetition work), cylindrical workpieces are invariably held in a collet inserted into the spindle and secured either by a drawbar, or by a collet closing cap on the spindle.
16、Suitable collets may also be used to mount square or hexagonal workpieces. A circular metal plate with even spaced holes around the periphery, mounted to the spindle, is called an index plate. It can be used to rotate the spindle a precise number of degrees, then lock it in place, facilitating repea
17、ted auxiliary operations done to the workpiece. Modes of use When a workpiece is supported at both ends, it is more stable may be applied to the workpiece, via tools, at a right angle to the axis of rotation, without fear that the workpiece may break loose. When a workpiece is mounted with a certain
18、 axis of rotation, worked, then remounted with a new axis of rotation, this is referred to as eccentric turning or multi axis turning. The result is that various cross sections of the workpiece are rotationally symmetric, but the workpiece as a whole is not rotationally symmetric. This technique is
19、used for camshafts, various types of chair legs, etc. Varieties The smallest lathes are jewelers lathes or watchmaker lathes, which are small enough that they may be held in one hand. Although the workpieces machined on a jewelers lathes are metal, jewelers lathes differ from all other metal working
20、 lathes in that the cutting tools are hand held and supported by a T-rest, not fixed to a cross slide. Two spindle bore sizes to receive the collets are common, namely 6 mm and 8 mm. Two patterns of bed are common: the WW (Webster Whitcomb) bed, a truncated triangular prism (found only on 8 mm watch
21、makers lathes)； and the continental D-style bar bed (used on both 6 mm and 8 mm lathes). Lathes that sit on a bench or table are called bench lathes. Lathes that do not have additional integral features for repetitive production, but rather are used for individual part production or modification as
22、the primary role, are called engine lathes. Lathes with a very large spindle bore and a chuck on both ends of the spindle are called oil field lathes. Fully automatic mechanical lathes, employing cams and gear trains for controlled movement, are called screw machines. Lathes that are controlled by a
23、 computer are CNC lathes. Lathes with the spindle mounted in a vertical configuration, instead of horizontal configuration, are called vertical lathes or vertical boring machines. They are used where very large diameters must be turned, and the workpiece (comparatively) is not very long. A lathe equ
24、ipped with indexing plates, profile cutters, spiral or helical guides, etc., so as to enable ornamental turning is an ornamental lathe. Various combinations are possible: e.g. one could have a vertical CNC lathe (such as a CNC VTL), etc. Lathes can be combined with other machine tools, such as a dri
25、ll press or vertical milling machine. These are usually referred to as combination lathes. 毕业设计（论文） 外文翻译（译文） 车床 车床是一种机器，它旋转着一块材料去执行多项操作，如：用工具切割，打磨，滚花，钻孔，或变形，这些适用于工件去做一个可绕对称轴转动的实物。 车床用于 木料车削加工 ，金属加工， 和玻璃加工 。车床可用于陶器 成形 ，最有名的设计是陶轮。装备最完善的 金工车床还可以用来生产 旋转物 体，飞机表面 物体 和螺纹或螺旋。 装饰用的 车床 可以 生产非常复杂的 三维 物 体。材料是 靠
26、 一个或两个中心 点保持位置不动 ，至少 其中 一 个 可 以水平 移动，以适应不同材料的长度。 可由车床生产的实物例子包含细 棒， 桌 腿，碗，棒球棍，曲 轴和凸轮轴。 车床是一种古老的工具， 至少可追溯到古 埃及人，并 被 希腊，罗马和拜占庭帝国 等一些国家所知道和使用 。 车床的 起源转折点 为公元前 1300 年 左右， 那时 埃及人 发明 了 第一台需 两个人 操作 的车床。一个人 用一条粗绳把木头工件翻转过来，同时另一个人 用 锋利的工具削木头 。罗马人改进了埃及 人 的设计， 他添 加了一个 车削的弓形部件 。早期 的 弓车床 也被 德国，法国和英国 这些国家的人发明和使用 。在
27、中世纪 的时候， 脚踏代替手工操作 车削 ，使 两个 工匠 都可以空出手来去拿木头切削工具 。踏板通常被连在一根直的幼苗杆上 。今天该系统被称为 “反弹 杆 ” 车床。 反弹 杆车床是在 20 世纪初 被共同使用 。那台需两 人 操作的 车床被称为 “ 伟大的车 床”，它允许 不 停翻转（就像如 今的电力车床 ）。师傅 削减木材， 同时 学徒 旋转 曲柄。 在工业革命 期间， 车床是 机动 化 的 ， 它让木料在更短的时间内变成实物 ，并允许金属 在 车床 上加工 。 电动机 也产生 一个 更大的转速， 使车床更 方便 地快 速 进行 高质量的 加 工。今天，大 部分 商业车床是计算机操作 的
28、，允许用于 大规模生产， 它 可 达到制 造精度 且不需花成本雇佣工匠 。 车床的部分构件 : 车床 或许有又或许没有一个支撑架 ， 它直接被放在地板上， 提升车床 基座到 工作高度。一些小车床 就被放在工 作台或桌上 ，并没有 支撑架 。 几乎所有的车床 都 有一个 “基座” ， 它 是（几乎总是） 一个 横向梁（ 即使 有些数控车床 在基座上 有一个垂直梁，以确保 金属细 屑，或 碎屑 ， 能从基座上自由掉落）。一个显著的例外是 Hegner VB36 Master Bowlturner,它是为车削大木球而设计的车床，其基本构造是小的而不是大的启闭。 在 基座的 一端（ 当操作者 面 向
29、车床 时， 几乎总是在左边 的 ）是一个 “ 启闭 ” 。 这个 启闭包含高精确度旋转轴承。 在轴承里旋转的是一根水平轴，和另一轴平行于基座，叫做“主轴”。主轴往往是中空的，在内侧发动机上有外部线 程和内部锥度，靠小配件把工件固定在主轴上。住轴也许也有外部线程和内部锥度或有一个手轮或其它配件在它们一端的外部电动机上。主轴受驱动，传递动力给工件。 主 轴驱动，要么 靠来自 踏板和飞轮 的动力，要么靠连向 动力源 的传送带 。在一些现代的车床 中，这种 动力 源是一个不可 缺少 的电动马达 。 除非 主轴上的 一个工件锥度 可 加工到它完 全 契合内部锥度，或 是主轴有 线程完全匹配外部线程（两件
30、事情几乎不会发生）， 主轴 必须 得用配件 安装一个工件。 工件 也许是用螺栓扣住或用螺丝拧紧在 面板 上 ， 一块 大 的 平板架 固定在主 轴 上 。工件可夹 在卡盘里头 ， 卡盘 直接 固定 在主轴 上 或 固定 在 某 个轴 上 。 在精密的工作中（和在某些类别的重复工作中），圆柱形工件总是用一个夹头插入主轴和一个拉杆固定，或由一个夹头限制主轴。夹头也许也用于固定方形或六角形工件。一块边缘有洞的圆形金属板固定在主轴上，被称为“索引模块”。它可用于旋转轴到某个精度，然后锁定到位，促进反复操作的工件的精度。 车床的 使用模式 : 当一个工件的两端 可以支撑 ，这 可以使工件更稳定， 通过工具， 旋转轴与之成一个直角 ， 就 不用再 担心工件 会 发生松动。 当工件被固定与一个确定的旋转轴，让它工作，然后再重新固定于一个新的
