在基于在机测量结果的基础上,提出新的获得自由曲面加工误差的方法,对曲面的面轮廓度误差进行评定.该方法利用在机测量加工曲面上少量测点的坐标数据,通过重构NURBS曲面控制点拟合加工曲面.考虑求解优化问题的适应性,利用最速下降法优化计算加工曲面到理论曲面的距离,获得曲面的加工误差,对曲面的面轮廓度误差进行评定.采用该方法在NURBS曲面工件上进行实验验证.结果表明,基于在机测量NURBS曲面控制点重构的方法能够有效、快速地进行自由曲面加工误差的分析和评定.
A new method to get the machining error of free-form surface was proposed based on the results of on-machine measurement in order to evaluate the profile error of machined surface. A small amount of points on machined surface were measured by on-machine measurement, and the machined surface was obtained by reconstructing the control points of the NURBS surface based on the on-machine measurement data. Considering the adaptability of solving optimization problems, the steepest descend method was used to calculate the distance between the machined surface and the theoretic surface, which could get the machining error of the whole free-form surface. Then the profile error of machined surface was evaluated. The proposed method was conducted in the measuring and analysis of NURBS surface workpiece. Results show that the method based on on-machine measurement data and reconstruction of NURBS control points is effective and rapid for the measuring and analysis of machining error of free-form surface.