装配尺寸模型的建立及应用∗

摘要

A new method of establishing the assembly dimension model is presented to obtain the design da-tum、dimension and tolerance. On the basis of the concept of functional dimension, given two principles of selection of functional dimension, and then all the assembly functional dimensions can be identified. By in-troducing the concept of"tree" from the graph theory, under the principles of"the shortest path" and"high precision priority", with assembly datum as its center point, the tree graph of the relationship between func-tional dimensions and the component sizes were established, which also could be called the path diagram of assembly dimensions. The path diagram can be optimized according to the requirement of the process、testing and marking habit, so as to get the complete and reasonable routes. The path diagram can express the datum of design of apart, and the dimension model established by the path diagram can fully express the relation-ship between all functional dimensions and component sizes, which is a new idea to improve the quality of dimension design and the parametric design.%为了准确获得装配体中各零件的设计基准、尺寸和公差，提出一种建立装配体尺寸模型的方法。在功能尺寸概念的基础上，给出功能尺寸选取的两个原则，然后确定装配体的全部功能尺寸。引入图论中“树”的概念，以基准为结点，在功能尺寸“路径最短”和“高精度优先”两个原则的驱动下，建立起功能尺寸与零件尺寸关系的树图，即装配尺寸路径图，再根据各工件加工、检验和标注习惯的要求对路径图进行改进，得到更合理的路径图。路径图不但表达了零件的设计基准，而且所建立的尺寸模型还完整地表达了全体功能尺寸与零件尺寸的关系，为提高尺寸设计质量及参数化设计提供了一种新方法。