五轴数控渐进成形干涉检测与修正研究

A Study on the Interference Detection and Correction in 5-Axis CNC Incremental Forming

综合考虑干涉检测效率、精确性和可修正性,提出一种高效、精确的基于STL(Sterolithography)数据模型的五轴数控渐进成形挤压工具与工件干涉检测与修正方法。以八叉树分割立方体最小边为基准对STL模型的三角面片细分后再沿边进行离散进而确保离散点云模型的八叉树分割更为均匀,并把离散点八叉树分割模型拓展为一个带有索引序列的八叉树分割模型以便不经过递归查找就能直接检测干涉区域;然后把挤压工具用轴向AABB(Axis-aligned bounding boxes)包围盒进行包围并利用八叉树分割模型粗略检测发生干涉的位置;最后利用八叉树分割模型立方体节点内的离散点和圆柱体形状的挤压工具对可能发生干涉的位置进行细致检测,并在干涉点处沿着挤压工具轴线方向的剖切面上进行干涉修正。算法应用实例表明,该方法能够快速而准确地寻找出干涉点的位置并能予以修正,整个过程运行稳定可靠。

A kind of high efficient and accurate method for the interference detection and correction of 5-axis CNC incremental forming tool and sheet part on the basis of STL （Sterolithography） model is proposed considering the detection efficiency, accuracy and correction. STL model of sheet part is discretizated along the edges after the triangular facets have been subdivised according to the minimum edge of the cube obtained by octree division algorithm so that the octree segmentation for the discrete point cloud model are more regularly. And in order to directly detect the interference area without recursive search, the discrete point cloud model is expand to an octree division model with index sequence. Meanwhile the forming tool is surrounded by axis-aligned bounding boxes and the interference location is detected through the octree division model roughly. The interference location is detected in detail through the discrete points in cubes of the octree division model and the forming tool of the cylinder shape. The interference correction is conducted on the section cutting plane which is along the axis direction of forming tool at interference points. The case study shows that the proposed method can quickly find the interference as well as give the correction, and the whole operation process is stable and reliable.