面向大规模复杂三角网格的模具CAD算法

项目名称： 面向大规模复杂三角网格的模具CAD算法

项目编号： No.61070125

项目类型： 面上项目

立项/批准年度： 2011

项目学科： 金属学与金属工艺

项目作者： 李维诗

作者单位： 合肥工业大学

项目金额： 12万元

中文摘要： 采用三角网格模型直接设计模具可以显著提高模具开发的效率。目前，脱模方向自动分析算法的效率较低，采用通用算法得到的三角网格上的分型线一般很不光滑，无法满足模具设计和加工的需要。本项目验证了采用直线性量度确定粗略候选脱模方向的可行性，并对申请人已经提出的零亏格三角网格上光滑分型线的构造算法和模型局部修改算法进行了进一步的探索，为进一步的研究奠定了基础。 在以前的三角网格补洞研究中，发现现有的基于边界三角化的方法不能处理复杂边界，本项目利用扭结理论中的高斯图,提出了一种分割投影为自覆盖多边形的空间多边形并对其歧义性进行分析的方法。本项目还研究了平面区域等距后的全局拓扑变化问题，利用中轴变换，系统分析了区域向内/向外等距后可能的拓扑变化，并在此基础上提出了确保拓扑变化的开/闭操作。

中文关键词： 三角网格;粗略脱模方向;空间多边形;分割;等距

英文摘要： The efficiency of the mold development process can be improved remarkably if triangular meshes can be used in mold design directly. However, existing automatic algorithms for determining parting directions are still not efficient enough for large-scale mesh models. Furthermore, parting lines generated for triangular meshes using existing algorithms are generally not smooth, and they can not be used in mold design and machining. In this project, the feasibility of computing the rough candidate parting directions using rectilinearity measure has been proved, and the smooth parting line generation algorithm for the zero-genus triangular mesh and the local modification method for the model have been explored further. The research achivement of this project set up a base for further research of direct molding for meshes. In the research of hole filling for meshes, we found that the existing methods based on triangluation of boundary curves can not process complex boundary curves. In this project, a method for decomposing 3D polygons with self-intersecting projections and detecting the ambiguity has been proposed, based on the Gauss diagram in knot theory. The global change of an offset domain has also been investigated in this project. The possible topological changes of an inward/outward offset domain have been analysed using the medial axis transform of the domain, and reliable opening/closing has been proposed to deliberately change the topology of the domain.

英文关键词： Triangular mesh; Rough parting direction; 3D polygon; Decomposing; Offset