Research on assembly modeling and sequence planning based on features

Abstract

To take full advantage of CAD models information of product for assembly sequence planning (ASP), a product hierarchy model based on assembly features was presented. In this model, both single parts and subassemblies were united as a basic assembly unit (AU) to form a product. By constructing the assembly feature matrixes (AFM), the information of degree of freedom (DOF) for an AU could be found out by analyzing the AFM and the probability of removing this AU from assembly could be also ascertained. Based on the hypothesis that an AU can be disassembled then be assembled, the disassembly heuristic rules, the global disassembly direction and the connecting relations of different AU were analyzed. With these analyses the disassembly/assembly sequence of an assembly was acquired. Considering the selecting principle of basic AU, the parallel degree of assembly sequence and the number of reorientation in assembling process, the assembly sequence was optimized by fusing these factors. Taking a ball-valve model as example, these theories and its achieve process was described.