快速原型制造中反求工程关键技术的研究

【作者】 上官建林；

【导师】 刘德平；

【作者基本信息】 郑州大学 ， 机械电子工程， 2007， 硕士

【摘要】 快速原型制造技术(RPM)是现代技术的前沿，在RPM中引入反求工程(RE)，具有十分重要的意义，实现了RE／RPM间的信息集成，从而形成了一个集设计、制造、检验于一体的快速反馈设计系统。所以，随着现代计算机技术及测试技术的发展，利用CAD／CAM技术、先进制造技术来实现产品实物的反求工程，已成为CAD／CAM领域的一个研究热点，并成为反求工程技术应用的主要内容。本论文以扫描线点云数据为研究对象，着重在点云数据的处理、反求工程与快速原型制造的集成和曲面重构等几个关键技术环节进行了深入的研究和讨论。本论文主要完成的工作有以下几点：(1)点云数据的处理：主要从点云数据的获取、点云数据的分类及点云数据的预处理等几个方面进行了深入研究。提出了非定最小距离数据精简算法与中值滤波和加权中值滤波相结合的混合滤波数据平滑算法。并通过实例说明了整个数据预处理过程的算法原理和数据处理，且验证了其有效性。(2)反求工程(RE)与快速原型制造(RPM)的集成：针对目前CAD模型与快速原型制造技术的接口文件STL格式存在的不足，本文提出一种由点云数据直接实现自适应分层的处理方法；不但可以避免表面网格化所带来的误差，而且无需借助中介的文件转换格式，提高了RPM的效率和精度。(3)曲面重构：NURBS曲面重构，可以精确地表示二次规则曲线曲面，从而能用统一的数学形式表示规则曲面与自由曲面，而其它非有理方法无法做到这一点。国际标准化组织(ISO)于1991年颁布了关于工业产品数据交换的STEP国际标准，将NURBS方法作为定义工业产品几何形状的唯一数学描述方法。从而使NURBS方法成为曲面造型技术发展趋势中最重要的基础。本文主要研究NURBS曲面的重构。(4)软件实现及实例验证：首先说明了软件开发对计算机的基本要求；然后概述了软件的整体设计以及各模块的功能；通过实例说明了自适应分层在快速原型制造方面的有效性。更多还原

【Abstract】 Rapid prototype manufacturing (RPM) is the advancement of the modern technology, so it has very important meaning for quoting reversing engineering (RE) in PRM:completed the information integration between RPM and RE,and formed a fast feedback design system including designing,manufacturing and inspecting.So with the devolepment of modern compute technology and test technology, RE using CAD/CAM technology and modern manufacture technology to complete part’s prototype, has becoming a study hotpoint in CAD\CAM field,and the main content of RE technical application.In this paper, some key technologies of RE based on the point cloud data obtained from laser scanner are deeply studied and discussed, including the preprocessing of data points, the intetation of RE and RPM and the methods of surface reconstruction.This paper chiefly has finished the tasks as follows:(1) Processing of data points: The study for processing of data points in this paper is mainly concentrated capturing, classifying and preprocessing of the data point .Mainly, through deeply analyzing and studying in removement of the noisy, caculating and analyzing of data point, reduction and smoothing of cloud point data, a kind of changeable minmum distance method and a kind of fixture filtering- median filtering and weighed-median filtering are imposed in this paper. And the algorithm principle and data processing of the whole data processing process has been described by a practical example, also verified its validity.(2) The integration of RE and RPM: To the shortage of the interface file of RE and RPM—STL style, in this paper a kind of adaptive slicing method is proposed,which not only avoids the error form grid melts approximate,but doesn’t need the intermediary file to converse;So tthe precision and efficiency of RPM is improved.(3) Surface reconstruction: NURBS surface reconstruction may express twice regular curve and curved surface accurately, so it can express regular curved surface and freeform curved surface using unified mathematics form,and other non-rationed method can’t do this. ISO has promulgated the STEP international standard about industrial product data exchange, and looked NURBS method as only mathematics description method defined industrial product geometry shape, which makes NURBS method the most important foundation in the modelling technical development tendency of curved surface. NURBS surface reconstruction is mainly studied in this paper.(4) Software completing and example testing: Firstly, system developed for the basic requirement of computer is explanated; Later, the whole designs of software and the function of every module are illustrated;Last, the effectivity of adaptive slicing is testified in RPM by an example .更多还原