Abstract: To improve the tool path continuity and reduce the cutter load fluctuation,the tool path generation method on triangular mesh surface based on modified butterfly subdivision was proposed.The machining model of cutter-contact point was built based on the geometric analysis of triangular mesh surface and toroidal cutter.The minimum cutter tilt angle and maximum machining strip width were obtained to avoid the interference of cutter and workpiece.Modified Butterfly subdivision method was applied to the triangular mesh surface to ensure the tool path interval within the strip width.The boundary of surface was selected as the initial tool path to obtain the cutter location according to the geometric model of toroidal cutter which the subsequent tool paths were generated along the edge of triangular mesh.The tool path with better continuity which could reduce the cutter load fluctuation was generated and applied according to the specified cutter parameter and scallop height.

Key words: NC machine, tool path, triangular mesh free-form surface, modified Butterfly subdivision

摘要： 针对刀具轨迹连续性差、切削刀具负荷波动大的问题,提出一种基于改进型Butterfly细分的三角网格曲面环形刀具轨迹规划方法。以三角网格曲面的几何特征为基础构建曲面定点数据表达结构,结合环形刀的几何特征对刀触点(CC点)的刀具曲面及工件曲面进行几何分析,构建三角网格曲面环形刀切削模型。根据切削刀具干涉原理计算刀具的最小前倾角以获得切削路径的最大宽度,并据此采用改进型Butterfly细分方法对三角网格曲面进行细分,使刀具轨迹的行距达到切削路径宽度的要求。以曲面轮廓曲线为初始刀具轨迹,沿着三角网格边界进行螺旋型刀具轨迹刀触点(CC点)的逐行规划,最终根据环形刀几何模型求解刀心(CL点)位置。根据选择的刀具参数和给定的残余高度要求,仿真生成的三角网格曲面螺旋刀具轨迹的连续性好,从而降低了切削刀具负载的波动,最后通过机加工实验验证了刀具轨迹的可行性。

关键词: 数控加工, 刀具轨迹, 三角网格自由曲面, 改进型Butterfly细分