【作者】 蒋红海；

【导师】 何国金；

【作者基本信息】 广西大学 ， 机械电子工程， 2003， 硕士

【摘要】 许多国内外流行的优秀CAD／CAM软件都声称其曲线、曲面模型建立在NURBS(非均匀有理B样条)理论和方法的基础上。但如何应用这种理论和方法进行软件设计，在系统中实现CAD功能，由于知识产权保护的缘故，没有公开，所以查不到有关这方面的技术文献。在这种情况下，为了开发适用于我国中小企业的图形交互式数控编程软件，本文基于已有的NURBS方法对自由曲线、曲面与初等解析曲线、曲面(如直线、圆锥曲线、二次曲面、旋转曲面等)的统一数学描述理论，模索出这一理论在CAD／CAM软件开发中的实际应用方法，并采用OpenGL技术和VC++6.0语言，开发了二维图形CAD基本功能模块，包括基本绘图功能、图形编辑功能、辅助绘图功能等。采用交互式控制DOF对NURBS曲线、曲面的设计与修型和通过移动曲线曲面上的控制点对B样条曲线和贝塞尔曲面的交互式直接修型两种方法，开发了曲线、曲面CAD模块； 本文还对数控编程软件开发中外轮廓加工的数控代码生成和代码文本文件输出进行了初步的研究与开发。更多还原

【Abstract】 Modern CAD systems widely adopt NURBS(non-uniform rational B-spline) as the main modeling entity because they can represent other commonly used parametric curves and surfaces, while also being able to precisely present the natural quadric shapes such as cones and cylinders. Because of the protection of intellectual property, no references about the application to commercial CAD systems based on the method can be found. In this case, in order to develop a NC programming software applicable to the small business enterprise in our country, a method applied in a CAD/CAM system based on a unified mathematical form NURBS offered is proposed in the thesis. Besides, based on OpenGL graphics packages and Visual C++ programming language, two-dimensional drawing module, which includes two-dimensional drafting, edit function and aid drawing function etc., is developed in the software. Until now, all interactive design schemes proposed can be classified into two categories. One is the control point based method, which manipulates curves and surfaces by controlling the DOF (degrees of freedom) defining them. And the other is the so-called direct manipulation method. According to this method, selected points on a curve or a surface are moved to new user-defined locations. In the curve and surface modules of this system B-splines curves and Bezier surfaces are manipulated by moving their control points to new user defined locations. And for NURBS curves, the extra degree of freedom called weights is used to manipulate the shape ofcurves or surfaces.In the thesis, the preliminary research and development are made in the generation of NC codes for outline machining and output of NC codes text file.更多还原