含孤岛型腔铣削加工的螺旋刀轨生成算法

Spiral tool path generation algorithm for milling pocket with island

当型腔含有孤岛时,使用传统环切铣削方法加工往往难以避免拐角方向存在突变的问题,故提出一种螺旋刀轨生成算法,实现含凸边界孤岛型腔的快速铣削加工。首先在孤岛和型腔的加工轮廓上设置放样点,将放样点连接成放样线,线性插值放样线生成螺旋折线;接着插入以指数函数规律分布的控制顶点,并以其所定义的任意阶B样条曲线规划最终刀轨。所生成的刀轨能适应孤岛偏心的情况。实验结果显示,与传统环切相比,高阶连续的B样条曲线刀轨可直接用于具有NURBS插补功能的加工中心,孤岛轮廓的加工精度高,可有效避免刀轨方向突变,降低切削力的变化幅度,提高加工效率。

Conventional contour-parallel tool path patterns are inapplicable for milling pockets with islands at high speed because of sharp turning corners.To solve this problem,a new tool path generation algorithm is presented.Firstly,the setting-out points are set on the boundary of island and pocket,and a spiral fashion polyline is created by linearly interpolating the setting-out straights which are connected from the setting-out points of island and pocket.Then,the control points are inserted into the polyline under exponential regularization.Finally,the smooth tool path is generated via any order B-spline curve fitting.The tool path is applicable to pockets with bias island.The experimental results show that compared with the traditional contour-parallel tool path,high-order B-spline curve tool path can be sent directly to machine controller with NURBS interpolation function,the change range of cutting force will be decreased,meanwhile the machining accuracy of island and machining efficiency of pocket will be improved.