参数曲面高精度加工中的弦高误差控制

A Confined Chord Error Algorithm for High Precision Machining of Parametric Surfaces

在零件精加工过程中,弦高误差的大小对于零件表面精加工质量影响显著。由于参数曲面弦高误差计算的复杂性,提出两类参数曲面加工中的弦高误差控制算法,它是利用插补点处弧长误差、坐标值及一阶导数信息间接对弦高误差进行控制。其中插补点处的弧长误差由梯形公式求出,插补点处的坐标值及一阶导数信息由插补算法得到,使得总计算量的增加并不显著。对算法的误差情况进行讨论,并利用Nurbs曲面的仿真实例证实此算法能够在满足实时性要求的前提下,达到预定的弦高误差加工精度。

The quality of NC maching is greatly influenced by the chord error during high precision machining.A confined chord error algorithm for machining complex parametric surfaces is proposed for the complexity of the chord error.The information of the arc length error is utilized to control the chord error of the interpolated point indirectly.The arc length error of the interpolated point is computed by trapezoidal expressions,and the information of the coordinates and the first order derivative of the interpolated point is computed by the interpolation algorithm,so the computing difficulty is not increased greatly.The computed error of the algorithm is disscussed.A simulation example of NURBS surface prove that the pre-set precision of the chord error can be satisfied by this algorithm.