数控技术 外文翻译 外文文献 英文文献.doc

外文翻译
NUMERICAL CONTROL
Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers,letters,and other numbers,letters,and symbols are coded in an appropriate format to define a program of instructions for a particular work part or the job changes,the program of instructions is capability to change the program is what makes N/C suitable for low-and medium-volume is much easier to write programs than to make major alterations of the processing equipment.
There are two basic types of numerically controlled machine tools:point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors,with the result that the position of the machining head Can be assured only pletion of a movement,or while only one motor is of this type are principally used for straight—line cuts or for drilling or boring.
The N/C system consists of the ponents:data input,the tape reader with the control unit,feedback devices,and the metal—cutting machine tool or other type of N/C equipment.
Data input,also called “man—to—control link”,may be provided to the machine tool manually,or entirely by automatic methods when used as the sole source of input data are restricted to a relatively small number of of manuall