基于STL数据模型的NURBS刀轨生成算法

Algorithm for NURBS Tool Path Generation Based on STL Data Model

为了提高数控加工的加工效率,提出了一种适用于STL数据模型的NURBS刀轨生成算法。由刀触点计算无干涉直线刀轨的刀位点;采用最小二乘法将刀位点拟合成NURBS切削刀轨,在拟合过程中,计算拟合偏差及投影点参数,并用投影点参数对刀位点参数进行修正。在切削刀轨之间采用NURBS曲线过渡;通过调节节点矢量,使得切削刀轨和过渡刀轨在连接处保持C1连续。实验结果表明,采用文中算法生成的NURBS刀轨具有较少的控制顶点、较高的拟合精度以及较好的光顺性。

To improve efficiency of NC machining,an algorithm for NURBS tool path generation is put forward for STL data model.CL（Cutter Location） points of interference-free line tool paths are first computed according to CC（Cutter Contact） points.Then,NURBS cutting tool paths are generated by fitting these CL points into NURBS curves.In the fitting process,deviation of CL points and parameters of projected points are calculated and parameters revision of CL points is conducted.Transition tool paths are implemented by NURBS curves,and knot vector adjustment is used to keep the connections of cutting and transition tool paths C1 continuity.Experimental result indicates that the NURBS tool paths generated by the proposed algorithm hold fewer control points,higher fitting accuracy and better smoothness.