Unit 2 Numerical Control of Production Equipment
Unit 2 生产设备的数字控制

Numerical Control (NC) is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols. The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work-part or job.
数控是程序控制的自动化,在数字控制系统中,设备通过数字,字母和符号来编码,以一种合适的格式为每一个特定的零件或工件定义一个程序指令集。
When the job changes, the program of instructions is changed. The capability to change the program is what makes NC suitable for low-and medium-volume production. It is much easier to write new programs than to make major alterations of the processing equipment.
当工件变化时,程序也变化,改变程序的能力亦适合中小批量生产。写一个新程序比改变大量生产设备要容易的多。
Basic Components of NC
数控基本结构
A numerical control system consists of the following three basic components:
数控系统由下面三部分组成
Program of instructions
控制程序
Machine control unit
机器控制单元
Processing equipment
加工设备
The program is fed into the control unit, which directs the processing equipment accordingly.
程序输入到控制单元由送入的程序来引导加工设备控制。
The program of instruction is the detailed step-by-step commands that direct the processing equipment.
指导程序是一步步详细的指导加工设备的指令。
In its most common form, the commands refer to positions of a machine tool spindle with respect to the worktable on which the part is fixtured.
通常指令把主轴上刀具相对于安装工具的工作台定位。
More advanced instructions include selection of spindle speeds, cutting tools, and other functions. The program is coded on a suitable medium for submission to the machine control unit.
更多先进的说明包括主轴的转速,加工工具的选择及其功能。
The most common medium in use over the last several decades has been 1-in.-wide punched tape.
程序刻在合适的介质中,提交到机器控制单元中,在过去几十年中,最常用的介质是一英寸宽的打孔纸带。
Because of the widespread use of the punched tape, NC is sometimes called "tape control". However, this is a misnomer in modern usage of numerical control .
由于打孔纸带的广泛使用,NC有时也叫纸带控制,然而这是现代数控使用的误称。
Coming into use more recently have been magnetic tape cassettes and floppy diskettes.
现在进入使用更多的是磁带和软盘。
The machine control unit (MCU) consists of the electronics and control hardware that read and interpret the program of instruction and convert it into mechanical actions of the machine tool or other processing equipment.
机器控制单元,MCU由电子和控制硬件组成,机器控制单元可以读出和执行指令程序,可以自动改变加工工具和其他加工设备。
The processing equipment is the third basic component of an NC system. It is the component that performs useful work.
执行单元是数控系统的第三基础部分,执行原件是有效执行工作的原件
In the most common example of numerical control, one that performs machining operations,
最常见的数控例子其中的一个加工操作,加工设备由工作台和主轴组成,就像用电动机来驱动一样。
The processing equipment consists of the workable and spindle as well as the motors and controls needed to drive them.
加工设备由控制单元来驱动控制系统的类型。