【正文】 62956 . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL 、 Fundamental of NC Technology 、 Classifications of NC Machines 、 Features of Numerical Control and Its Application Areas Course Description: ? NC is one of the most important achievements in mechanical engineering field in 20 century. ? It is a crossing and integrating technology prising of puter technology, automatic control technology, information technology, sense technology, and machining technology. ? Numerical Control Technology has became one of the important technical basic classes of mechanical engineering specialty. Toshiba events . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL 、 Development History of NC 1946the first puter appeared in the world, which lift the curtain on the mankind into information time. 1948Parsons Corporation brought forward using puter to control machine when they machined the surface contours of airfoil shape. Parsons Corporation was a minihelicopter manufacturer. The machining accuracy of the airfoil shape was 177。 (3)Application of NC . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC Motion Control System Motion control systems for NC can be divided into two types: (1) Pointtopoint control system (點(diǎn)位控制系統(tǒng) )。 （連續(xù)控制或 輪廓 控制系統(tǒng)） . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC Motion Control System Pointtopoint control system Point –to point (positioning) control in NC It is also called Positioning control system, Which moves the worktable to a programmed location without regard to the path taken to get to the location. That is to say ,the path between points is of little concern and is not particularly controlled. The program consists of a series of point locations at which operations are performed. Such as drilling or punching a hole. . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC Motion Control System pointtopoint control system Many NC point –topoint systems contain a more plex MCU. IN these servos, positioning mands are evaluated simultaneously so that vector motion in two axes is possible. The movements between points can be done along straight or 450 vectors paths determined by the machine ways or slides. Such systems are some times called straightcut control system.（點(diǎn)位 /直線） . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC Motion Control System Contouring Control System It is also called continuous path control system, which manages the simultaneous motion (resultant motion)of the cutting tool in two, three, four, of five axes by interpolating(插補(bǔ) )the proper path between prescribed points. It enables the cutting tool to generate angular surfaces, twodimensional curves, or threedimensional contours in the workpiece, such as milling and turning operations. . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC Motion Control System Interpolation To cut along a circular path,the circle must be divided into a series of straightline segments that approximate the circular tool is manded to machine each line segment in succession so that the machined surface closely matches the desired shape. . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC ServoDrive System The principal function of NC is the positioning of the tool or the machine table in accordance with the programmed data. Industry has developed three different types of drives based on how the NC system acplishes positioning. These are the openloop（開環(huán)） , the closedloop（閉環(huán)） and half closedloop（半閉環(huán)） drive system. . Chapter 1 INTRODUCTION TO NUMERICAL CONTROL Types of NC ServoDrive System OpenLoop ServoDrive It is the simplest and least cost form of