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1、, NC Technology Email: jtbguet.edu., Numerical Control Technology ,机电工程学院 主讲： 蒋廷彪, NC Technology Email: jtbguet.edu.,Ch4 COMPUTER NUMERICAL CONTROL UNIT, NC Technology Email: jtbguet.edu.,Outline,CNC system HARDWARE ARCHITECTURE OF CNC UNIT CNC Software OPEN ARCHITECTURE SYSTEM FOR CNC UNIT, NC Tech
2、nology Email: jtbguet.edu.,Introduction,Machine controls are divided into two types: numerical control (NC) computer numerical control (CNC). NC controls have to read the program each time a part is run; they have no means of editing existing programs. CNC controls can store and allow editing of loa
3、ded programs. All machines built today are CNC machines. CNC unit is the heart of CNC machine., NC Technology Email: jtbguet.edu.,NC system,The NC machine : control unit, which processes the commands from the input media. the drive mechanisms the machine itself The most basic function of any NC mach
4、ine is automatic, precise, and consistent motion control., NC Technology Email: jtbguet.edu.,The makeup of a linear axis of an NC machine, NC Technology Email: jtbguet.edu.,CNC System,Definition (EIA): CNC system is a special computer system that is equipped with certain interface circuits and servo
5、 drivers, and can do part or all the works an NC system do by running the software stored in its memories. EIA(美国电子工业协会)所属的数控标准化委员会的定义: “CNC是用一个存储程序的计算机，按照存储在计算机内的读写存储器中的控制程序去执行数控装置的部分或全部功能，在计算机之外的唯一装置是接口”。 ISO(国际标准化组织)的定义: “数控系统是一种控制系统，它自动阅读输入载体上事先给定的数字，并将其译码，从而使机床移动和加工零件”。, NC Technology Email: jt
6、bguet.edu.,CNC machining System,Logical structure of CNC machine tool, NC Technology Email: jtbguet.edu.,CNC machining System, NC Technology Email: jtbguet.edu.,CNC系统的组成,从自动控制的角度来看，CNC系统是一种位置（轨迹）、速度（还包括电流）控制系统，其本质上是以多执行部件(各运动轴)的位移量、速度为控制对象并使其协调运动的自动控制系统，是一种配有专用操作系统的计算机控制系统。 从外部特征来看，CNC系统是由硬件（通用硬件和专用
7、硬件）和软件（专用）两大部分组成的。, NC Technology Email: jtbguet.edu.,CNC装置的组成和工作原理, NC Technology Email: jtbguet.edu.,CNC装置的组成和工作原理,硬件结构: CPU，存储器，总线、外设等。 软件结构：是一种用于零件加工的、实时控制的、特殊的（或称专用的）计算机操作系统。, NC Technology Email: jtbguet.edu.,CNC装置的组成和工作原理,3. 工作原理 通过各种输入方式，接受机床加工零件的各种数据信息，经过CNC装置译码，再进行计算机的处理、运算，然后将各个坐标轴的分量送到各控
8、制轴的驱动电路，经过转换、放大去驱动伺服电动机，带动各轴运动。并进行实时位置反馈控制，使各个坐标轴能精确地走到所要求的位置。 简要工作过程： 1）输入： 输入内容零件程序、控制参数和补偿数据。 输入方式穿孔纸带阅读输入、磁盘输入、光盘输入、手健盘输 入，通讯接口输入及连接上级计算机的DNC接口输入., NC Technology Email: jtbguet.edu.,CNC装置的组成和工作原理,2）译码：以一个程序段为单位，根据一定的语法规则解释、翻译成计算机能够识别的数据形式，并以一定的数据格式存放在指定的内存专用区内。 3）数据处理：包括刀具补偿，速度计算以及辅助功能的处理等。 4）插补
9、：插补的任务是通过插补计算程序在一条曲线的已知起点和终点之间进行“数据点的密化工作”。 5）位置控制：在每个采样周期内，将插补计算出的理论位置与实际反馈位置相比较，用其差值去控制进给伺服电机。 6）I/O处理：处理CNC装置与机床之间的强电信号输入、输出和控制。 7）显示：零件程序、参数、刀具位置、机床状态等。 8）诊断：检查一切不正常的程序、操作和其他错误状态。, NC Technology Email: jtbguet.edu.,CNC unit,CNC unit is the core of the whole CNC system. It is composed of hardware
10、 and software. The hardware : microprocessors, electronic memory modules, I/O interfaces, and position control modules, etc. CNC software controls all functions of the machine and its efficiency of operation, and manages all local programming at the machine tool and graphic simulation of the cutting
11、 process if available. The hardware and the software work together to do all functions of CNC unit, which an ordinary NC system can never do., NC Technology Email: jtbguet.edu.,The main functions and features of CNC unit,Controlling function (the number of control axes and synchronously control axes
12、) Preparatory function Interpolation function Feed function Feed Rate Override Rapid motion Spindle function, NC Technology Email: jtbguet.edu.,The main functions and features of CNC unit,6. Miscellaneous function 7. Compensation function Tool length compensation, cutter radius compensation , and to
13、ol nose radius compensation. Technical parameters compensation 8. Enhanced graphic display function 9. Self-diagnosis function 10. Communication function 11. Programming function, NC Technology Email: jtbguet.edu.,Functional interface between hardware and software in CNC unit, NC Technology Email: j
14、tbguet.edu.,HARDWARE ARCHITECTURE OF CNC UNIT,CNC unit is the core of CNC system. The hardware comprising a CNC unit is made up of microprocessors, electronic memory modules, I/O interfaces, and position control modules, etc. , which is just like an ordinary computer system., NC Technology Email: jt
15、bguet.edu.,Types of CNC Unit,by the architecture of printed circuit boards All-in-one board architecture multi-functional modules architecture by the number of microprocessors single microprocessor multi- microprocessors by the manufacturing fashions ordinary personal computer architecture special p
16、urpose architecture according to their opening degree Close architecture PC-plug-in-NC architecture NC-plug-in-PC architecture software based open architecture of CNC unit, NC Technology Email: jtbguet.edu.,All-in-one board architecture,All-in-one architecture CNC unit comprises main board, position control card, PLC card, displayer card, and power supply. Main board is a big printed circuit board; other f
