Abstract: Aiming at the automatic generation problem of assembly dimension chain,a new method based on feature-expression of directed graph was proposed.An- assembly precision information model with four-layer structure was constructed to standardize the tolerance information and transform the constraint information.On this basis,the geometric tolerances characteristic matrix and assembly features correlation matrix were obtained.By using the graph theory,a directed graph assembly model was established which rejected the irrelevant vertices and edges of directed graph,and the automatic generation of assembly dimension chain was realized with the minimum path theory.A prototype system was developed by using ACIS and HOOPs geometric modeling tool to verify the proposed method.The result showed that the search range of assembly dimension chain was reduced by this method effectively,and the accuracy of automatic generation of assembly dimension was ensured.

Key words: precision information model, graph model, tolerance chain, incidence matrix

摘要：

关键词: 精度信息模型, 图论模型, 尺寸链, 关联矩阵