外文翻译=普通车床的主轴箱设计=1300字符

外文资料翻译译文 普通车床的主轴箱设计 主轴箱组件紧固在车床左端。它由主轴箱主轴组成，经齿轮或齿轮组和皮带轮使主轴旋转。主轴有可装夹并转动工件的附件。主轴有多级转速。主轴箱由 35 个支座支承。由于车床上工件的加工精度取决于夹持工件的主轴旋转轴的精度，故必须十分仔细地制造和安装主轴及其所有附件。 主轴本身有一个通孔，这个孔的前端是一锥孔，可用来安装带锥柄的刀具。安装主轴箱活顶尖时，用一锥套配入主轴的锥孔内。主轴箱顶尖可随工件旋转，故可称活顶尖。它是一个带尖端的锥金属件。工件旋转时可用来支承工件，所有车床 顶尖均为 60角。 在主轴上安装附件，常使用三种通用的主轴头： 1. 螺纹主轴头 车床上最常用的是螺纹主轴头。将安装的附件拧到主轴上，直到与主轴法兰盘紧密相配。螺纹主轴头的主要缺点是不能进行反向车削，因有些附件（例如卡盘）反向时会松开。 2. 凸轮锁紧主轴头 凸轮锁紧主轴头有一个非常短的锥体，她可以配入花盘或卡盘背面的锥槽内。从花盘或卡盘背面伸出许多凸轮锁紧短轴，这些短轴可配入主轴头的孔内。转动这些凸轮就可将它们锁紧在规定位置。 3. 长锥键传动主轴头 它有一个很长的锥体。锥体带一附加键和一内螺纹套爪。花盘或卡盘必须与其锥度相同并带有外螺纹键槽。这种正向锁紧型主轴在中型车床中最为普遍。它允许主轴在正向或反向旋转时均能切削。 驱动主轴的动力由一电动机供给，从电动机将动力传递给主轴有四种常用的方法： 平皮带传动 在大多数皮带传动的车床中，直接驱动动力通过皮带传递给附在主轴的塔轮上。把皮带移动到塔轮的不同位置，就可改变主轴速度。为获得较低速和较大动力，可使用背轮。 背轮的工作原理见图 2-3。齿轮 F 紧固在主轴上，常称齿轮 F为大齿轮。塔轮的小端有一小齿轮 E。塔轮转动时，齿轮 E 总是转的。塔轮的小齿轮通过一个称作大齿轮锁紧 销的滑动销与大齿轮相连。床头箱背面有两个安装在同一轴上的齿轮。它们间隔排开，与大齿轮 F 和小齿轮 E 相啮合。这些齿轮叫背轮。为了使背轮啮合，要推出大齿轮销子（此销子推出时，塔轮和小齿轮转动而主轴不转）。向前推背轮手柄，使背轮与大齿轮 F和小齿轮 E相啮合。接通电源时，决不能用手转动塔轮使其啮合。啮合时，动力直接由背轮传递给大齿轮 F和主轴。 床头箱左端有一反向进给杆。它用于丝杠的反向运动。此杆有三个位置。在上自动进给位置时，床鞍将向床头箱方向（即向左）移动，横进给向外运动。 三角皮带传动 每个皮带轮的圆周上都开有一个 V型槽。三角皮带将精确地嵌入槽内。三角皮带不能碰到皮带轮的底部。这种传动方式也有一个与平皮带传动相似的背轮装置。 无级变速传动 这种装置不用停车就可以改变主动轮和从动轮间的速度。实际上只有在机床运行时才需变速。无级变速传动的传动皮带轮由二个 V 型侧面的半轮组成。皮带轮的一侧可以是打开的，即与另一侧脱开。在脱开时，皮带就向里移动到较小直径，使从动轮产生较低速度。当皮带轮两侧合在一起时，就迫使皮带轮向外移动到较大直径，使从动轮速度增大。可以用手动或液压进行变速。采用液压方式时，床头箱顶部的控制盘可使液压系统精确动 作。电动机停止时，不要转此控制盘。直接传动的转速范围为 3001600转 /分。 4. 齿轮传动变速箱 这种床头箱包括齿轮和变速机构，可获得许多不同的转速。操作者可使用附在床头箱上的速度分度盘来选择所需的速度。移动两个或三个手柄或摇手就可调节速度。 外文原文 Headstock of Engine Lathe The headstock assembly is permanently fastened to the left end of the lathe. It contains the headstock spindle, which is rotated by gears or by a combination of gear and pulleys. The spindle holds the attachments which, in turn, hold and turn the workpiece. Spindles come in several quality ratings and are supported in headstocks by three to five bearings. Since the accuracy of the work done on a lathe depends on the axis of rotation of the spindle holding the workpiece, the spindle and all its accessories must be built and assemble with the greatest possible care. A hold extends through the spindle itself. The front end of this hole is tapered for holding tools having a tapered shank. A taper sleeve (a hollow-round part) fits into the taper spindle hole, when holding a headstock, or live center. The headstock center is called a live center because it turns with the work. The center is a tapered metal part with a pointed end. It is used to support the end of a workpiece as it is being turned. All lathe center point have a 60-degree() included angle. Three common types of spindle noses are used to hold attachments on the spindle. 1. The threaded spindle nose has been used on lathes longer than any of the other types. Attachments to be mounted are screwed onto the spindle until they fit firmly against the spindle flange. The major disadvantage of the threaded spindle nose is that turning cannot be done in the reverse position (with the spindle turning clockwise). This is Because certain attachments, a chuck for example, would come loose. 2. The cam lock spindle nose has a very short taper which fits into a tapered recess in the back of a faceplate or chuck. A series of cam lock studs projects from the back of the faceplate or chuck. These cam lock studs fit into the hole in the spindle nose. They are locked into position by turning a series of cams. 3. The long (steep) taper key drive spindle nose has a long taper with a key attached and an internal threaded collar. The faceplate or chuck must have an equal taper and keyway plus an external thread. This positive lock-type of spindle is most popular on medionum-size lathes. It permits cutting with the spindle turning in either direction. Power for driving the spindle is provided by an electric motor. There are four common ways of transmitting the power form the electric motor to the spindle. These include: Flat belt drive. On most belt-driven lathes, direct drive power is delivered through belts to a step pulley attached to the spindle. The spindle speed is changed by moving the belt to different positions on the step pulley. To obtain slower speeds and more powder, back gears are used. To understand how the back gears operate, study Fig, 2-3 Notice that gear F is fastened securely to the spindle. This gear is often called a bull gear. The small end of the step pulley gas a small gear attached to it called a pinion gear. This gear (E) always turns when the pulley turns. The step pulley and pinion gear are connected with the bull gear by a sliding pin called the bull-gear lock-pir. At the back of the headstock are two gears mounted on the same shaft. They are spaced to line up or mesh with the bull gear (F) and pinion gear (E). These are called back gears. To engage the back gear, the pin in the bull gear is pulled out (when the pin is out, the pulley and pinion gear will turn, but the spindle will not turn). Pull the back gear handle forward to mesh the back gears with bull gear F and pinion gear E. Do this by turning the step pulley by hand-never while the power is on. When engaged, power is delivered directly to the bull gear (F) and spindle by the back gears. At the left end of the headstock assembly is a feed reverse lever. It is used for reversing, the direction or movement of the lead screw. This lever can be moved to three positions. When it is in the upper position with the automatic feed engaged, the carriage will move to-ward the headstock (to the left) and the cross-feed will move in. When in the center position, the gears are out of mesh and the lead screw will not move. When in the lower position with the automatic feed engaged, the carriage will move toward the tailstock (to the right) and the cross-feed will move out. V-belt drive. A V-shaped groove is cut around the circumference of each pulley, and a V belt fits accurately into this groove. The V belt does not touch the bottom of the pulley. This type of drive has a back gear arrangement similar to that used on flat belt machines. Variable-speed driver. In this arrangement it is possible to change the speed between the driver and driven pulleys without stopping the lathe. In fact, the speed must be changed only when the machine is running. The driving pulley of a variable-speed drive is made with parts having V-shaped sides. One side of the pulley may be opened or spread apart from the other side. As it spreads apart, the belt moves inward toward the smaller diameter, producing a slower speed on the driven pulley. As the sides of the pulley are brought together, the belt is forced outward toward the large diameter which increases the speed of