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COMPUTER NUMERICAL CONTROL PROGRAMMING BASICS phần 3

hợp nhất các điểm trục cá nhân vào một con đường công cụ được xác định trước được xây dựng vào hầu hết các MCUs ngày nay. Có năm phương pháp nội suy: tuyến tính, tròn, xoắn ốc, parabol, và khối. Tất cả các điều khiển đường nét cung cấp nội suy tuyến tính, và hầu hết các điều khiển có khả năng nội suy tuyến tính và vòng tròn. | merge individual axis points into a predefined tool path is built into most of today s MCUs. There are five methods of interpolation linear circular helical parabolic and cubic. All contouring controls provide linear interpolation and most controls are capable of both linear and circular interpolation. Helical parabolic and cubic interpolation are used by industries that manufacture parts which have complex shapes such as aerospace parts and dies for car bodies. Linear Interpolation Linear Interpolation consists of any programmed points linked together by straight lines whether the points are close together or far apart Fig. 11 . Curves can be produced with linear interpolation by breaking them into short straight-line segments. This method has limitations because a very large number of points would have to be programmed to describe the curve in order to produce a contour shape. A contour programmed in linear interpolation requires the coordinate positions XY positions in two-axis work for the start and finish of each line segment. Therefore the end point of one line or segment becomes the start point for the next segment and so on throughout the entire program. Fig. 11 An example of two-axis linear interpolation. Kelmar Associates 16 Circular Interpolation The development of MCUs capable of circular interpolation has greatly simplified the process of programming arcs and circles. To program an arc Fig. 12 the MCU requires only the coordinate positions the XY axes of the circle center the radius of the circle the start point and end point of the arc being cut and the direction in which the arc is to be cut clockwise or counterclockwise See Fig. 12. The information required may vary with different MCUs. Fig. 12 For two-dimensional circular interpolation the MCU must be supplied with the XY axis radius start point end point and direction of cut. Kelmar Associates Programming Format Word address is the most common programming format used for CNC programming systems. .