Research On Parametric Curve And Parametric Curved Surface Interpolation Algorithm And Acceleration-Deceleration Control For CNC System

Numerical control technology is the critical technology of modern equipment manufacturing industry, which determines the function and performance of manufacture equipment. Parameter curve and curved surface interpolation are the symbolic function of modern number control system. As the core of numerical technology, interpolation technology especially the precision and the speed of parameter curve, curved surface interpolation and acceleration deceleration control algorithm are playing a decisive role in the modern CNC system performance. The research of theory and application for these two aspects is done deeply in this paper.The interpolation algorithm of introduced error compensation for complex parametric curve in space (IAIECCS) is proposed for the high precision interpolation of parametric curve on the basis of studying the first, second order taylor expression parametric curve interpolation algorithm and the plane parametric curves interpolation algorithm. The error compensation is introduced in the interpolation algorithm to increase the interpolation point's solution precision of the parametric curve, and the reasonable simplification of the compensation expression is carried in the solution process to decrease the calculation load of interpolation. The simulation example of Nurbs curve proves that the calculative precision of the interpolation point's parameter value can be increased greatly on the premise that the real time performance of the numerical control system is satisfied.The high precision tool path planning algorithm of introduced error compensation (HPTPPAC) is proposed for the high precision interpolation of translational scanned curved surface and curved surface of which respective direction curvature changed slowly on the basis of studying parametric method tool-path generation for parametric surface. The error compensation is introduced in the interpolation algorithm to increase the interpolation point's solution precision in the cutting direction of the parametric curved surface. The reasonable simplification of the computed result of the interpolation point's parameter value is carried in the operation process by focusing on the character that curvature of slow-varying parametric curved surface changed slowly and the feature that the scanned profile of translational scanned curved surface is parallel along the scanned line. The simulation example of parametric curved surface proves that the calculative error of interpolation point's parameter value can be decreased greatly under the condition that the real time performance of the numerical control system is satisfied.The high precision tool path planning algorithm with error compensation for complex parametric surfaces—high precision tool path planning algorithm of error compensation (HPTPPACPS) is proposed for the interpolation of complex curved surface on the basis of studying the constant scallop-height tool path planning for parametric surface. The interpolation point's solution precision of the complex parametric curved surface is improved through the introduction of the error compensation. Meanwhile, the computed result is simplified reasonably to decrease the calculation load of interpolation according to the feature in Numerical control processing of complex parametric curved surface. The simulation example of complex parametric curved surface prove that the calculative precision of the interpolation point's parameter value of the complex parametric curved surface can be increased obviously on the premise that the real time performance of the numerical control system is fulfilled.The modified acceleration deceleration control algorithm of trigonometric function (MADCATF) is proposed on the basis of studying the acceleration deceleration control algorithm of trigonometric function. The continuity of acceleration deceleration displacement,speed,acceleration and jerk function is satisfied by the form of the acceleration deceleration displacement function. The analysis of algorithm performance is shown that MADCATF can solve the problem of the acceleration deceleration control algorithm of trigonometric function and the merit of acceleration deceleration control algorithm of trigonometric function is kept. So the machining accuracy of the part and work efficiency are improved, and the stationarity of the movement of the machine tool in processing course is guaranteed effectively.According to the algorithm above, the module of the parametric curve interpolation, the parametric curved surface interpolation and MADCATF is introduced during the development of the eight-five axis CNC system. The high speed, and high precision machining of the parametric curve, the parametric curved surface can be supported effectively to the CNC system.