Smooth Interpolation of Short Lines in Five-axis CNC Machining

doi:10.3901/JME.2016.12.001

Abstract

Abstract: In the programming of five-axis machining, computer aided manufacturing system manufacture usually uses lines instead of curves while surface machining. A large number of micro G01 straight line segments are used to machine surface, sharp creases will appear on surface of workpieces with large radius of curvature, which results in bad surface machining quality of workpieces. In order to improve the surface quality of workpieces machined by five-axis CNC machining system, a micro-line smooth interpolation algorithm for five-axis CNC machining is presented. In view of the dimensional difference of cutter axis vectors, our algorithm identifies discontinuous and continuous micro-line blocks of cutter axis vectors machining regions through the length of linearity axis, the angular variation of rotation axis and the intersection angle of linearity axis between adjacent command points. For the discontinuous micro-line blocks of machining regions, direct interpolation is conducted to guarantee the processing precision based on original lines and the rotation axis. For the continuous micro-line blocks of machining regions, get node parameters using five dimensions variables, least square method is used to correct command points in an allowed error range; Second-order tangent vectors of corrected command points are calculated by using four continuous corrected command points, cubic spline curves with continuity of second order are obtained according to corrected command points, node parameters and second-order tangent vectors; Real-time interpolation calculation is conducted on the second order smooth curves, machine tool is controlled to five-axis machining. Experimental results demonstrate that fitted path by smooth interpolation of micro lines in five-axis CNC machining is more close to the original surface model, the surface quality of smoothing pieces is better than the non-smoothing, our algorithm can improve the free curved surface quality of five-axis.

Key words: five-axis, interpolation, micro-line blocks processing, smooth fitting

CLC Number:

TG156

ZHAO Jianhua, ZHU Bei, LIU Fang, TAN Yundong, FAN Liuqun, GU Xianjie, HUANG Wei. Smooth Interpolation of Short Lines in Five-axis CNC Machining[J]. Journal of Mechanical Engineering, 2016, 52(12): 1-8.

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