| The melding of scientific knowledge and competitive manufacturing market, put higher requirements on the machining accuracy and efficiency of mechanical manufacturing. It predicts that manufacturing level of numerical control technology is toward high speed, high precision and multi-axis machining direction. Five-axis machining technology can one-time processing complex freeform surface parts,which is gradually replace the traditional triaxial processing. In the process of processing free-form surface, we usually adopt the method of linear approximation processing curve. This approach has led to long NC program that makes the load of storage and transmission too large, and discontinuity reduces the processing quality and speed. Spline interpolation can reduce the NC program and the speed’s fluctuation, so as to improve the quality of surface processing.PH curve is a kind of polynomial curve has many good properties. It has precise calculation of arc length and accurate representation of equidistant line, and keep the complete consistency with the Bezier curve. So this article studied the PH curve interpolation strategy in five-axis CNC system.This article propose vertex elimination approximation algorithm on the basis of Farouki rule of CC(cubic-cubic) interpolation algorithm firstly.This algorithm can reduce the computational burden of the traditional algorithm in order to improve efficiency. Secondly, the paper puts forward with arc length as parameter acceleration and deceleration control strategy, shorten the machine tools positioning time at low speed and reduce the impact. To deal with the CLS file generated by the CAM software, and is used to generate space PH curve for five-axis CNC interpolation algorithm. Finally, it sets the five-axis CNC interpolation of PH curve interpolation G instruction as well as the processing mechanism, then verifies the correctness and feasibility of the theory through spline interpolation algorithm and PH curve surface machining simulation. |
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