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 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 potter's wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads 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 include 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-person 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 pedal replaced hand-operated turning, freeing both the craftsman's 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 two-person lathe, called a "great lathe", allowed a piece to turn continuously (like today's 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 the 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 craftsmen. 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 (although 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 the 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 an 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 impart 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 internal 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 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. 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 repeated 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 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 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 jeweler's lathes are metal, jeweler's lathes differ from all other metal working 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 watchmakers 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 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 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 equipped 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 drill press or vertical milling machine. These are usually referred to as combination lathes.
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，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
旋转轴，这被称为“不同圆心的切削”或“多轴切削” 。其结果是工件的各种截面是旋转对称的，但整 个工件不是旋转对称的。这种技术用于凸轮轴，各种类型的椅子脚等地方。 车床的种类: 最小的车床是“制作宝石的车床”或“制造钟表的车床” ，它们足够小，也许用一只手可以拿住。 即使在制造珠宝的车床上加工的工件是金属， 它的切削工具不同于所有其它金属加工车床的切削工具， 是手持的，由一个支架支撑着，而不是固定在一个华东部件上。两个主轴孔大小的工件用夹头夹住是 很常见的，即六毫米和八毫米，两种模式的基座是常见的：Webster Whitcomb 基座，一个截短的三棱 镜（只在八毫米的钟表制造车床上发现） ；和大陆右旋风格的柜台式基座。放在长凳上或桌子上的车床 叫做“长凳车床” 。车床没有附加的用于重复生产的整体功能，而是以用于个人部分生产或改造作为主 要作用， 这样的车床叫做 “引擎车床” 有一个非常大的主轴孔和主轴两端各带一个卡盘的车床叫做 。 “油 田车床” 。全自动机械车床，采用一系列的凸轮和齿轮控制运动，被称为螺杆机。由计算机控制的车床 是数控车床。车床的主轴固定在一个垂直的配置上，而不是水平的配置，被称为立式车床或垂直钻孔 机。它们用在长度不是很长但直径相对非常大的工件必须要车削的时候。车床配备了索引板，剖面刀， 螺旋或螺旋指南等，以便使人观赏车削的是一种观赏性的车床。各种组合都是可能的：例如，人们可 以有一台垂直数控车床（如数控车床 VIL） 。车床可以结合其它机器，如钻床或立式铣床。这些通常被 称为组合机床。