Research Of Hierarchical Parallel Multi-station Assembly Sequence Planning Method Of Automobile Rear Independent Suspension Based On MBD

With the industrial upgrading of China’s manufacturing industry,the manufacturing industry is gradually moving towards digitalization,networking and intelligentization.In order to maintain an advantage in the market competition,enterprises must improve product quality and shorten product design and manufacturing cycle.According to the statistical results,the workload of assembly and debugging accounts for 20%～70% of the total manufacturing workload for mechanical and electrical products,assembly time accounts for 20%～50% of the total manufacturing time of products,as well as the assembly cost accounts for more than40% of the manufacturing cost in the modern manufacturing.Compared with the traditional serial single assembly mode,the automatic assembly planning of parallel transfer can greatly shorten the time of design、production and manufacturing.To solve the problems of the traditional assembly planning,this paper takes the rear independent suspension of automobile as an example to verify the automatic assembly planning method.The study includes assembly MBD modeling technology,assembly unit division method and parallel multi-station assembly sequence planning method.The main research contents of this paper include the following aspects:（1）Based on the investigation of the research and development of the rear independent suspension products,the assembly design and the actual assembly process in a domestic automobile enterprise,combined with the analysis of the current assembly information modeling technology at home and abroad,as well as the constraints of parallel multi-station assembly.The assembly MBD information model data set is constructed with part information,hierarchy information,matrix information and resource information.（2）This paper presents a method of assembly unit division for automobile complex assembly body.Firstly assembly relationship graph model is constructed and the basic parts are selected by using the best unit division formula and fuzzy cluster analysis.Then the assembly unit is divided based on the universal gravitation formula of Dijkstra algorithm to realize the division of product assembly unit reasonably.（3）Based on the actual requirements of enterprises’ production and assembly and the goal of shortening the assembly time of products,a hierarchical parallel multi station assembly sequence planning model is proposed.According to the results of assembly unit division,the hierarchical structure tree is reconstructed,and the fitness function including feasibility index,time cost index and assembly line balance index is constructed.The parallel assembly sequence of products is acquired by using the Genetic Algorithm and Discrete Frog Leaping Algorithm（GA-DFLA）.The results are verified by the flexsim software in the assembly line.By comparison,the assembly time of the parallel multi-station model of the rear independent suspension is 35.27%less than that of the serial multi-station model,which greatly improves the production efficiency of the enterprise.（4）Based on the NX10.0 secondary development technology,the MBD information system is developed.Taking the rear independent suspension as an example,the MBD data set of the rear independent suspension are realized.The MBD information system is of importance for enterprises to realize intelligent manufacturing and the automation of assembly planning.