中文摘要：

针对复杂曲面零件五轴加工中刀轴矢量变化剧烈、严重影响工件表面加工质量的问题，提出一种基于临界约束的五轴刀轴矢量整体优化方法。首先，构造了给定切触点处所有可行摆刀平面，并在摆刀平面内根据临界约束计算出临界刀轴矢量，在获得临界刀轴矢量的基础上，对其进行平面映射，建立了刀轴摆动的初始可行域；其次，通过对初始可行域进行均匀离散，根据离散点之间相对位置关系构造邻接矩阵，并结合最短路径搜索算法获得了初始参考刀轴，从而构造了新的刀轴摆动可行域；最后，建立当前切削行内无干涉且相邻刀轴变化最小的刀轴矢量优化模型，实现自由曲面五轴加工无干涉刀轴矢量的光滑控制。两种自由曲面叶轮的加工算例分析表明，采用本文方法获得的刀轴矢量可以明显改善机床的运动性能，避免了刀具干涉的产生，可提高复杂曲面零件的加工质量与效率。

英文摘要：

Dramatic change of tool orientation during a five-axis machining process of sculptured surfaces affects the machi- ning quality seriously. To solve the problem, a global tool orientation optimization method for five-axis machining is proposed based on critical constraints. Firstly, all the feasible swing planes according to the cutter contact points are constructed. Based on the critical constraints, critical tool orientations are obtained in the swing planes, and then the initial feasible tool orientation region is established with planar mapping. Secondly, by evenly discretizing the initial feasible region, an adja- cency matrix is constructed according to the relative position relationship of the discrete points. Together with the shortest path algorithm, the initial reference tool orientation is calculated and then a new feasible region is obtained. Finally, the op- timization model for tool orientation is established, which guarantees an interference-free current tool path as well as the smallest change between adjacent tool orientations. This method can realize the smooth control of tool orientation for five-ax- is machining of free-form surfaces without interference. Analysis of two different kinds of impellers with sculptured surfaces demonstrates that the tool orientation obtained by the proposed method can improve the movement performance of machine tools significantly, and the tool interference can be avoided. This method can thus improve the machining efficiency and qual- ity of parts with complicated curvatures