Abstract: To improve the machining accuracy of large-scale automobile outer cover molds,an on-machine measurement method of free-form surface machining errors was proposed.The triangular mesh was generated based on the improved wavefront method,the coordinate data of the theoretical surface mesh nodes were extracted,and the sampling data of the actual processed surface was obtained according to the on-machine measurement;then the surface was reconstructed based on the wavelet control point method of T-splines,and the processing curved surface was fitted;the normal distance from the reconstructed actual curved surface control point to the theoretical curved surface was calculated based on the generalized Newton method,the processing error distribution of the curved surface was obtained,and the profile error of the experimentally processed convex-concave surface sample was analyzed.The experimental results showed that the surface reconstruction method based on the T-splines control point method could effectively obtain the machining error of the free-form surface on the machine.

Key words: on-machine measurement, machining error, surface reconstruction, T-spline, wavelet control point method

摘要： 为了提高汽车车身外覆盖件模具的加工精度,提出一种在机测量自由曲面加工误差的方法。首先基于改进波前法生成三角网格,提取理论曲面网格节点的坐标数据,根据在机测量得到实际加工曲面的采样数据;然后基于T-splines的小波控制点法进行曲面重构,拟合加工曲面;最后基于广义牛顿法计算重构的实际曲面控制点到理论曲面的法向距离,获得曲面的加工误差分布,并对实验加工的凹凸曲面样件的轮廓度误差进行分析。实验结果表明,基于T-splines控制点法的曲面重构方法能够在机、有效地获得自由曲面的加工误差。

关键词: 在机测量, 加工误差, 曲面重构, T样条, 小波控制点法