【作者】 钟国宇；

【导师】 高健；

【作者基本信息】 广东工业大学 ， 机械电子工程， 2012， 硕士

【摘要】 随着数字化设计与制造技术的发展及其越来越广泛的工业应用,数字化曲面模型的构建与数控加工成为其核心环节。由于复杂曲面功能需求,使曲面模型的构建大多始于实物模型,曲面的三角网格模型表达已非常普遍,被广泛应用于快速原型制造中。然而,相比于较为成熟的参数曲面模型数控加工方法,基于曲面网格模型的直接数控加工系统研究则面临着一系列困难。本文基于曲面零件的三角网格模型,重点研究三角网格模型拓扑关系建立和偏置模型生成方法、偏置模型截面交点求取方法、曲线拟合算法等方法,实现数控加工代码生成及系统开发。本论文的主要内容包括：1)全面调研基于三角网格模型的数控加工领域的国内外研究现状,分析该领域的关键问题,指明当前面向三角网格模型数控加工存在的难点问题,确定面向三角网格模型的数控加工技术的研究内容与实施方案。2)深入研究三角网格模型的偏置模型生成方法,研究基于顶点法矢的偏置模型实现方法。在重构三角网格模型的拓扑关系的基础上,研究结合干涉判断的网格模型顶点法矢计算方法,研究实现高精度无干涉三角网格偏置模型的生成。3)在建立精确偏置模型基础上,研究基于拓扑关系的截平面法,并结合截平面法研究走刀方式和截面间距的确定方法,研究基于模型拓扑关系和优化求取网格模型交点的方法,实现精确网格模型交点的求取。4)基于截面法生成的网格模型交点,采用三次非均匀B样条插值法进行曲线拟合,并根据加工零件的曲面特征采用等参数离散确定步长,规划加工路径,生成加工代码。5)在上述研究的基础上,基于Visual C++开发工具和OpenGL技术,开发出面向三角网格模型的直接数控加工系统,并通过若干个网格模型实例,验证该数控加工系统的可行性和有效性。更多还原

【Abstract】 With the development of digital design and manufacturing technology and its increasingly wide range of industrial applications, the construction of digital surface models and CNC machining is becoming its core areas. More construction of surface model began in the physical model due to the complex surface functional requirements. the triangular mesh of the surface expression has been very popular and widely used for rapid prototyping. However, compared with more mature CNC machining methods of parametric surface model, the research of CNC machining system based on mesh model directly is facing a number of difficulties. In this paper, based on the STL triangular mesh models of model surfaces, we study the topological establishing of triangular mesh model and the generation of offset model, obtain intersection points of offset models using cutting plane method, the fitting of intersection points and so on, and generate NC code and system. The main work is detailed as follow:1) Investigating current research state of NC manufacturing of triangular mesh model, analyzing the key problems of this area, and proposing research work and an NC manufacturing strategy for triangular mesh model.2) Investigating generation method of offset triangular mesh model which is proposed and realized based on vertex offset. Investigating calculation method of vertex vector and judging method of interference on base of establishing reasonable data structure of triangular mesh model, and creating high precision as well as non-interference offset triangular mesh model.3) Investigating the cutting plane method based on topological after creating precision offset triangular mesh model and studying the tool path planning and manufacturing interval planning. Investigating and putting forward the improvement of calculation method of intersection points and realizing the accurate intersection method.4) Interpolating intersection points by Three times the uniform B-spline and calculating step length by iso-parameters approach, planning tool path according to the characteristics of the surface of parts and generating NC code. 5) On the basis of the above research, and through VC++6.0software and OpenGL technology, a NC manufacturing system for triangular mesh model was developed, and the feasibility and stability of the system was proved by experiment.更多还原