机械专业英语图解教程翻译.doc

P113 Numerical controlNumerical control of machine tools may be defined as a method of automation in which various functions of machine tools are controlled by letters, numbers and symbols. Basically a NC machine runs on a program fed to it. The program consists of precise instructions about the manufacturing methodology as well as the movements. For example, what tool is to be used, at what speed, at what feed and to move from which point to which point in what path, all these instructions are given. Since the program is the controlling point for product manufacture, the machine becomes versatile and can be used for any part. All the functions of an NC machine tool are therefore controlled electronically, hydraulically or pneumatically.In NC machine tools one or more of the following functions may be automatic:(1) Starting and stopping of the machine tool spindle.(2) Controlling the spindle speed.(3) Positioning the tool tip at desired locations and guiding it along. Desired paths by automatic control of the motion of slides.(4) Controlling the rate of movement of the tool tip.(5) Changing of tools in the spindle. Initially the need of NC machine was felt for machining complex shaped small batch components as those belonging to an aircraft. However, this spectrum currently encompasses practically all activities of manufacturing, in particular capital goods and white goods. Thus the range covered is very wide. Besides machining with which we are concerned in this book, NC has been used in a variety of manufacturing situations. The majority of applications of NC are in metal cutting machine tools such as milling machines, lathes, drilling machines, grinding machines and gear generating machines. Beside a number of metal forming machine tools such as presses, flame cutting machines, pipe bending and forming machines, folding and shearing machines also use NC for their program control. The inspection machines called Co-ordinate Measuring Machines are also based on NC. Lastly the robots basically may be material handling units, but their control principles are very close to the NC. Besides these applications listed for manufacturing, other applications such as filament winding or assembly machines based on the NC principles can also be seen in the industry. NC machines have been found suitable for the following:(1) Parts having complex contours, that cannot be manufactured by conventional machines tools.(2) Small lot production, often for even single job production, such as for prototyping, tool manufacturing, etc.(3) Jobs requiring very high accuracy and repeatability.(4) Jobs requiring many set-ups and/or when the set-ups are expensive.(5) Parts that are subjected to frequent design changes and consequently require more expensive manufacturing methods.(6) The inspection cost, which is a significant portion of the total manufacturing cost.One or more of the above considerations would justify the processing of a part by an NC machines tool.数控数控机床可以被定义为一个自动化的方法，其中工具机的各种功能的控制由字母，数字和符号。基本上是数控机床上运行一个程序给它喂食。该方案包括精确的制造方法以及变动说明。例如，要使用什么工具，在什么样的速度，饲料和移动至从哪个角度，这点在什么路径，所有这些说明，给出。由于该方案是产品的产品制造的控制点，该机器成为多功能的，并且可用于任何部分。数控机床上的所有功能的，因此，电子控制，液压或气动。在数控机床中的以下功能中的一个或多个可以是自动的：（1）启动和停止的机床主轴。（2）控制主轴转速。（3）定位刀尖在所需的位置，并引导它沿。期望路径由幻灯片的运动自动控制。（4）控制刀尖的运动速度。（5）改变的工具，在主轴。最初需要的数控机床用于加工形状复杂的小批量组件属于航空器感到。但是，该频段目前包括几乎所有的制造业活动，特别是资本货物和白色家电。因此涵盖的范围很广。我们关注在这本书中除了加工，NC已被用于制造各种情况。大多数应用数控金属切削机床，如铣床，车床，钻床，磨床，齿轮机。除了一些金属成形机床，例如机，火焰切割机，管材折弯成型机，折叠和剪切机也可以使用NC程序控制。检查机器称为数控测量机也是基于共同协调。最后，机器人基本上可能是材料处理单元，但其控制原理都是非常接近的NC。列出了制造除了这些应用，其他应用，如缠绕或NC原则的基础上组装机也可以看到，在该行业。数控机床已找到合适的项目如下：（