针对传统自由曲面笔式加工过程计算量大、加工效率低等问题,提出了一种圆弧逼近自由曲面的笔式加工区域搜索算法.首先利用改进的四叉树算法将自由曲面进行面片分割;然后利用圆弧逼近曲面近似计算曲率半径,快速搜索出曲面局部干涉的大体位置,减少了计算量,提高了搜索效率;最后通过二叉树法精确搜索笔式加工区域的边界点,形成笔式加工区域.实例分析表明,该算法能够快速、准确地搜索出干涉区域,搜索时间由传统逐点搜索法的85.047 s缩短至33.734 s,说明该算法是有效的.

In order to reduce the calculation complexity and improve the processing efficiency of pen-cutting process,an arc approximating method is proposed to detect the pen-cutting regions in the NC machining of freeform surfaces.In this algorithm,an improved quadtree algorithm is presented to subdivide and approximate the freefrom surface.Then,arc approximation is performed to approximately calculate the curvature radius for the purpose of quickly judging the local interference,reducing the calculation complexity and improving the search efficiency.Finally,a binary-tree method is used to exactly detect the boundary points and to determine the boundary of pen-cutting regions.Case results indicate that the proposed algorithm is effective because it can fast and accurately search the local interference regions,with a time cost reducing from the traditional 85.047s of the point-by-point searching to 33.734s.