【作者】 卫斌；

【导师】 邹北骥；

【作者基本信息】 中南大学 ， 计算机应用技术， 2008， 硕士

【摘要】 钣金件特征造型技术一直是CAD/CAM领域中重要的研究内容。经过二十多年的发展,虽然特征造型技术的研究取得很大成就并在实际生产设计中得到了广泛应用,但仍存在不少困难的问题有待进一步解决。本文以拓扑元素的命名与辨识和相交特征识别问题为核心,对钣金件特征造型技术中存在的关键问题开展研究。论文提出了一种拓扑元素命名和辨识的方法,其特点是在特征模型编辑后物体的拓扑结构发生变化时能有效地辨识出拓扑元素的前后对应关系,并能有效地支持钣金件相交特征识别。针对钣金件特点进行特征分类,采用特征二叉树存储结构建立钣金件主形状特征之间的关系,这种树状结构直观地反映了钣金件的构成和特征之间的连接关系,可运用成熟的二叉树算法,查询特征信息并为钣金件的自动展开提供基础。论文提出了基于抽象扩展属性邻接图(AEAAG:Abstract Extend-ed Attributed Adjacency Graph)的局部特征识别方法,采用AEAAG来表示钣金件特征模型,提出用拓扑元素信息生成辅助边,通过拓扑元素编号机制分离AEAAG,从而进行特征匹配,不但实现了钣金件相交特征的自动识别,而且能够在两个特征发生合并时提示用户进行特征合并。论文还提出了一种钣金件自动展开新方法,采用对特征树进行中序遍历得到钣金件的展开图。在上述研究的基础上,基于AutoCAD平台自主开发了钣金件特征造型原型系统SM-CAD(Sheet-Metal CAD),实现了钣金件特征设计和钣金件的自动展开。更多还原

【Abstract】 The feature-based modeling method for Sheet-Metal is always an important research area of CAD/CAM. It has achieved great progress and has been widely used in industries over last decade. However, there are still some challenging problems remained. This dissertation focuses on the research on identification and denomination of feature elements and the recognition of intersect features, as well as the related key research issues of feature technology.A new mechanism of naming and identifying topological entities of a feature model is proposed in this thesis, the advantage of the proposed approach is that the identified topological entities are more reasonable in respect to the design intent and it can effectively supported the interacting feature of Sheet-Metal parts.The thesis assorts the feature of Sheet-Metal and uses the approach of feature bintree to store the relation of main features. The structure of the feature tree can reflect the realation between the Sheet-Metal feature clearly and easily, and use the mature algorithom of bintree to get the information of the feature. And it also provides foundation for Sheet-Metal automatic unfolding.The thesis introduces a novel local feature recognition method based on AEAAG (Abstract Extended Attributed Adjacency Graph). AEAAG is used to express the feature model of the Sheet-Metal and the information of topological entities is utilized to generate the assistant edge. Newly generated AEAAG is decomposed and then the interacting features of Sheet-Metals are recognized by matching the subgraph. This method can automatically recognize intersection features of Sheet-Metal parts.A new mechanism which based on the in-order traversing feature binary tree of Sheet-Metal automatic unfolding is proposed in this thesis.Based on all above,we develop a system of SM-CAD (CAD system of Sheet-Metal) which can design the Sheet-Metal easily and unfold the Sheet-Metal automatic.更多还原