【作者】 王彩；

【导师】 陈树昌；

【作者基本信息】 天津大学 ， 机械设计及理论， 2004， 硕士

【摘要】 轴系零件是机械产品中的通用零件，应用较为广泛。而零件的装配质量又对产品性能有直接影响。目前的通用CAD软件在轴系零件的专业化设计及装配方面，尤其是在轴系结构的合理性判断方面，进行的研究较少。本文采用了MDT6.0（Mechanical Desktop）作为开发平台，采用MCAD VBA作为二次开发工具，对MDT6.0进行了二次开发，来实现对轴类零件的参数化三维实体造型、轴系零件的虚拟装配以及轴系结构的合理性判断等功能。本文采用面向对象的设计思想和模块化思想，将整个系统分为三大模块：零件三维实体造型模块、虚拟装配模块、装配结构合理性判断模块及错误修改模块。系统对轴系零件结构进行抽象，设定了轴系单元基本体素等，通过特征拼合实现了零件的特征造型。并将各类零件抽象成零件类，如轴类、轴承类等，通过类的封装及继承性，便于后续模块进行信息提取和判断。系统通过人机交互来实现轴系零件的参数化设计。在进行虚拟装配的研究中，通过定义插入约束、贴合约束等装配约束来保证轴系零件间的装配定位。通过定义装配模型数据库，来方便以后合理性判断中对装配数据的提取。本文还通过定义知识规则建立专家系统知识库，在归纳总结轴系结构中常见错误的基础上，运用规则推理方法提取零件及装配信息，对轴系结构的细节方面进行分析、判断，并输出结果。由此来判断轴系结构是否合理，若不合理，对零件或装配信息进行修改，使设计达到合理要求。更多还原

【Abstract】 Shafting parts are widely used in mechanical products. In the course of designing products, the quality of parts’ assemblies is very important. Current CAD software is not enough in the professional design of shafting parts and their assembly, especially in the rationality of shafting assembly structure. In this paper, based on MDT6.0, using MDT VBA as developing tool, the functions of parameterization modeling of shafting parts, virtual assembly of shafting parts and the rationality judgement of assembly structure are realized.Focusing on the Object-Oriented theory and modularization theory, this thesis devided the system into three modules: shafting parts’ 3D geometric modeling module, virtual assembly module, assembly rationality analysis and error-modified module. Through abstracting the structure of shafting parts, the system defines basic graphic units and realizes the characteristic modeling of shafting parts through Boolean operations on graph units. Based on Object-Oriented technique, shafting parts are divided into several kinds of classes, such as shaft segment class, standardized-part class etc. Because of the encapsulation and succession characters of class, the above method is of advantage to the pick-up of information. Parameterization design of shafting parts is realized by the interaction between human and computer.In the study of the virtual assembly module, the parts’ orientations are determined by defining assembly constraints, such as insert, mate etc. And the foundation of assembly modeling database give facilities for the information’s pick-up in the rationality analysis.The concept of “knowledge” is introduced into the assembly rationality analysis module. Based on the summarization of shafting structure’s familiar mistakes, a knowledge database is established using the describing method of Post. Through setting rules in the knowledge database, the rationality analysis of shafting structure can be completed. If there are mistakes in the shafting assembly structure, the design of shafting parts and assembly constraints can be modified to make the whole design right.更多还原