用于加工弧面凸轮轮廓曲面的NURBS插补方法

在分析弧面凸轮轮廓曲面上加工刀痕产生的原因,以及对分度机构性能影响的基础上,提出了用NURBS样条插补凸轮从动件运动规律曲线的思想方法.通过对NURBS样条插补改进算法的深入分析,得出了进一步校正满足加工步长条件的NURBS样条参数增量的算式.同时对插补前弧面凸轮从动件运动规律曲线的修正、NURBS插补误差和插补过程的实现进行了计算与分析.结果表明,采用文中给出的方法,能显著提高弧面凸轮轮廓面的加工精度.

NURBS interpolation method used for machining curved profile surface of arc surfaced cam

On the basis of analyzing the reason of producing machining tool mark on the curved surface of the camber surfaced cam profile and its influence on the performance of dividing mechanism, the method of thinking for interpolating the motion rule curve of cam follower by the use of NURBS spline was put forward. Through deep analysis on the improved algorithm of NURBS spline interpolation, the formula for further rectifying the NURBS spline parametric increment that satisfies the step length condition of machining was obtained. Calculation and analysis were carried out at the same time on the rectification of motion rule curve of arc surfaced cam follower before interpolation and on the realization of NURBS interpolation error and interpolation process. The result showed that the machining precision of profile surface of arc surfaced cam could be increased remarkably by adopting the method presented in this paper.