南京航空航天大学 博士学位论文 修复牙牙弓线提取及磨牙冠数控加工关键技术研究与实现 姓名：王奇峰 申请学位级别：博士 专业：航空宇航制造工程 指导教师：廖文和;程筱胜 2009-10 南京航空航天大学博士学位论文 I 摘 要 CAD/CAM 技术在口腔修复领域的广泛应用，推动口腔修复技术向高效、自动、高精度、 低成本的方向发展。本文以口腔修复体为研究对象，研究了牙弓线提取技术，并运用高速切削、 计算机科学和数控编程技术，基于 STL 数据模型，对磨牙冠加工刀轨生成算法和难加工生物材 料的切削性能进行了较为深入的研究。 论文的主要研究内容和成果： 1. 研究了三角网格曲面的数据预处理技术，采用了基于平衡二叉树的快速搜索算法，提高 了拓扑重建的速度；联合了 Laplcian 算子和 Taubin 算子的优点，提出了组合算法，在满足光顺 精度的前提下，提高了光顺的效率。实现了一种通过模拟光线跟踪的效果，可视化评价曲面质 量的方法。 2. 提出了一种在三角网格牙颌模型上快速精确探测牙弓线的方法， 该方法通过简单人机交 互确定咬合平面、筛选初始参照点、拟合初始牙弓线、提取最终参照点、拟合最终牙弓线五个 步骤，能够快速、稳定、精确地在三维牙颌模型上探测牙弓线。 3. 提出并实现了基于牙齿生理特征与工作机理的五轴联动加工刀轨生成算法， 该算法有利 于改善牙齿局部特征的成形精度和修复质量。 4. 研究了磨牙复杂曲面数控加工刀轨优化技术，提出了基于顶点的实体等距算法、磨牙冠 高速精加工刀轨优化算法和基于 STL 格式的五轴联动高速铣削加工刀轨生成算法， 提高了加工 效率并实现了刀轴矢量的均匀变化。 在上述技术研究的基础上，采用 VC+和 Hoops 平台研发了原型系统，针对医用 Ti-6Al-4V 钛合金和 Zirconia 氧化锆材料，进行了口腔磨牙冠复杂曲面的自动编程基础算法验证，结果表 明加工质量能满足口腔临床修复的要求。 关键词：关键词：口腔修复学，CAD/CAM，高速切削，刀轨优化 修复牙牙弓线提取及磨牙冠数控加工关键技术研究与实现 II Abstract CAD/CAM technology has been widely applied in the field of dental restoration and promotes the efficiency, precision, automation, and economy of prosthodontic technology. Dental restoration is the research object in this thesis. The extraction technology of dental arch feature curve is studied in this work. Based on the high speed cutting technology, computer graphics, CNC machining technology and the STL data model, the tool path generation algorithms of molar crown high-speed machining and the cutting performance of hard processing organic material was studied in this thesis. The main contributions of this work are as follows: 1. The technology of data preprocessing of the triangle mesh surface is studied firstly. In this paper, an algorithm of quick search based on the balanced binary tree is proposed to increase the speed of rebuild topology. One algorithm that combines the advantage of Laplcian and Taubin operator is presented. While meeting the fairing accuracy requirement, this combinational algorithm enhances the efficiency of fairing. One method to simulate the ray tracing effect is brought out to evaluate the surface quality visually. 2. One method of detection of the dental arch curve on the 3D mesh dental cast is presented, and it can detect the dental arch curve quickly, steadily and accurately. This method includes five steps. Firstly bite plane is located by simple human-computer interaction. Secondly the initial reference points are filtered. Thirdly the initial dental arch curve is fitted. Fourthly the final reference points are extracted. Lastly the final dental arch curve is fitted. 3. Based on physical characteristics and working mechanism of the teeth, an algorithm of 5-axis machining tool path generation has been put forward and also been realized, which can help improving the local characteristics of the teeth forming accuracy and repair quality. 4. Tool path optimization for complex molar surface by NC machining is studied. The vertex-based surface offset algorithm, a tool path optimization algorithm of high-speed molar crown machining and a tool path generation algorithm of high-speed 5-axis simultaneous milling in STL format is presented. These methods can improve the processing efficiency and achieved an even change of the tool-axis vector. 南京航空航天大学博士学位论文 III On the basis of above research work, one automatically programming system of dental restoration is developed using VC+ and Hoops developing platform. The automatically programming algorithm of molar crown milling for the medical material Ti-6Al-4V and Zirconia is verified. The result shows that the manufacturing quality can satisfy the requirement of dental clinical restoration. Keywords: Prosthodontic, CAD/CAM, High-speed cutting, Tool path optimization 南京航空航天大学博士学位论文 IX 图表清单 图 1.1 CAD/CAM 技术在医学领域的应用 2 图 1.2 CEREC 3D 口腔修复系统图 2 图 1.3 CERCON 口腔修复系统2 图 1.4 KaVo Everest 口腔修复系统 3 图 1.5 传统修复体制作过程 3 图 1.6 数字化修复装备及瓷修复体 5 图 1.7 数字化修复氧化锆陶瓷牙贴面 5 图 1.8 ProceraAllceram 陶瓷磨削加工的各种修复体 6 图 1.9 KaVo Everest 系统铣削加工及制得的修复体 6 图 1.10 国产口腔修复 CAD/CAM 系统 8 图 1.11 论文研究路线 10 图 2.1 不均匀三角片 11 图 2.2 三角网格的单纯复形 K 定义 12 图 2.3 三角网格的拓扑结构12 图 2.4 半边数据结构13 图 2.5 三角片的半边拓扑关系图14 图 2.6 本文算法与三角片数据关系 18 图 2.7 本文算法与 rapidform 比较 18 图2.8 离散Laplacian调整 19 图 2.9 组合光顺图20 图 2.10 初始网格模型 22 图 2.11 Laplcian 光顺22 图2.12 Taubin光顺23 图 2.13 组合光顺 24 图 2.14 光顺精度比较 24 图 2.15 环境光反射图