组合曲面重构技术与数控加工实验研究

发布时间：2018-12-14 09:14

【摘要】：曲面重构技术是逆向工程中的关键技术,在曲面重构的过程中要保证重构曲面的部分特征以及较高的精度。基于不同数据格式的曲面重构的研究在机械制造领域一直是值得深入研究的热点问题。为此,本文针对鞋楦模型组合曲面进行保留特征的曲面重构研究,主要研究内容如下:(1)利用曲面求交算法对IGES格式组合曲面直接切片处理,得到切片数据用于后续的曲面重构,创建IGES读写引擎对组合曲面数据进行特征提取,对文件中的边界曲面特征进行离散化,对相邻接的边界曲面进行边线匹配,完成所有边界曲面三角剖分,并将三角剖分数据转换为标准STL格式文件。(2)对鞋楦STL格式文件进行切片处理,利用切片数据提取并光顺组合曲面特征棱线,构造曲面偏置曲线族,完成鞋楦楦筒部分的曲面延伸,对延伸部分进行再次切片处理,得到完整切片数据点,并对切片数据进行B样条曲线插值。(3)根据曲率确定出鞋楦模型每个切片曲线数据中的尖点,计算保留尖点特征的切片曲线数据参数,利用B样条计算方法获得重构曲面网格数据点,并考虑整体曲面的光顺性,提出优化曲线数据参数的方法,将组合曲面重构为单张B样条曲面。(4)利用C++语言进行了软件模块开发,实现了 IGES格式文件的切片功能、IGES格式与STL格式的转换功能、基于切片数据点的曲面延伸功能、保留特征的曲面重构,通过鼠标交互实现视图的基本变换,并将相关功能嵌入已有的CAM软件系统。最后,研究了鞋楦数控加工方法,并用五轴鞋楦数控机床完成了数控加工实验,实验结果验证了曲面重构的有效性。
[Abstract]:Surface reconstruction is a key technology in reverse engineering. In the process of surface reconstruction, some features and high accuracy of surface reconstruction should be guaranteed. The research of surface reconstruction based on different data formats has been a hot issue in the field of mechanical manufacturing. The main contents of this paper are as follows: (1) directly slicing the composite surface in IGES format by using the intersection algorithm of the surface. Slice data are obtained for subsequent surface reconstruction, IGES read-write engine is created to extract features from composite surface data, the boundary surface features in the file are discretized, and the adjacent boundary surfaces are matched by edges. The triangulation of all boundary surfaces is completed, and the triangulation data is converted into the standard STL format file. (2) the shoe last STL format file is sliced, and the feature edges of the combined surface are extracted and smoothed by slice data. The curved surface offset curve family is constructed, the surface extension of the shoe last part is completed, the extension part is sliced again, and the complete slice data point is obtained. The B-spline curve interpolation is carried out on the slice data. (3) according to the curvature, the tip points in each slice curve data of the shoe last model are determined, and the data parameters of the slice curve that retain the sharp point feature are calculated. The B-spline method is used to obtain the reconstructed surface mesh data points, and considering the fairing of the whole surface, a method to optimize the curve data parameters is proposed. The combined surface is reconstructed into a single B-spline surface. (4) the software module is developed with C language to realize the slicing function of IGES format file, the conversion function between IGES format and STL format, and the surface extension function based on sliced data points. The feature preserving surface reconstruction realizes the basic transformation of the view through the mouse interaction and embeds the related functions into the existing CAM software system. Finally, the NC machining method of shoe last is studied, and the NC machining experiment is completed with five-axis shoe last machine tool. The experimental results verify the effectiveness of surface reconstruction.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.7

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