The Study of Assembly Tolerance Relational Diagram Based on the Assembly Hierarchical Model

Hierarchical assembly model and the corresponding relation between assembly layer and tolerance layer are established based on the mapping form spatial relations of feature surfaces to the assembly tolerance. After the analysis of the assembly parts feature surface and its spatial relationships, the type of the assembly tolerance is determined, so as to the assembly tolerance diagram. In order to determine the parts assembly sequence, the freedom degrees of parts are calculated to determine the adequacy of the benchmark according to the conditions of assembly characteristics constraints. The effectiveness of the assembly tolerance relations diagram to the assembly planning is demonstrated through the case of flat vice in the end.