类回转体曲面数控加工刀位轨迹规划

Tool Path Planning of NC Machining for Surface Similar to Revolution Body

针对类回转体曲面高速进给数控加工,提出螺旋线驱动方式下圆环刀具加工轨迹的规划方法。构造螺旋线作为类回转体曲面的导动线,根据曲面上已知接触点轨迹的切线方向估算后续导动点对应的初始接触点。计算初始接触点处圆环刀具的刀心位置,再计算初始刀心位置与后续导动点对应的目标刀位点分别在圆周方向以及轴向的距离差值,利用相邻刀位点与相邻接触点存在的准相似关系,得到接近目标接触点的搜索方向和步长,经过迭代得到目标接触点和刀位点。在分析接触点处曲面曲率和圆环刀曲率的基础上,给出圆环刀加工误差计算方法。将所提出的算法用于鞋楦的五轴数控轨迹规划中,计算结果表明,该算法搜索效率较高,具有理论和实际应用价值,并通过鞋楦的五轴数控加工试验验证了算法的有效性。

Aiming at NC machining for surface similar to revolution body with high feed rate, a tool path planning method with toroid cutter under helix driving mode is proposed. Firstly, a helical line is constructed as the guide curve of the surface. Secondly, the initial cutter contact （CC） point corresponding with the subsquent guide point is estimated based on the tangential direction of the CC point locus known on the surface, and the center of the toroid cutter at the initial CC point is calculated. Thirdly, the distances between the initial cutter center and the objective cutter location （CL） point corresponding with the subsqent guide point in circumferential direction and axial direction are computed. Then the direction and step for searching the objective CC point are figured out with the quasi similarity relation between adjacent CL points and adjacent CC points. Finally the objective CC point and CL point are searched with an iterative process. Also the error calculation method is proposed based on analyzing the curvature of the surface and the cutter at CC point. The algorithm is used in tool path planning of shoe last 5-axis NC machining. The result shows that the algorithm works with a high searching efficiency and it has value of both theory and application. The shoe last 5-axis NC machining experiment is also carried out, which verifies the effectiveness of the algorithm.