A new approach of manufacturing tolerance allocation based on NSGA-Ⅲ algorithm for the in-process monitoring of sheet metal parts

摘要

As the process of products is developing, the contradiction between dimension quality and manufacturing cost should be balanced carefully.Excessive demands for higher quality would cause increase the production cost. Therefore, this paper will propose a new method of tolerance allocation based on NSGA-Ⅲ. At the beginning, the assembly precedence diagram and subassembly identification are used to obtain feasible assembly sequences. The assembly variation analysis model of the conceptual design stage was established. Afterwards, the assembly tolerance function was used to analyze the quality of the assembly, and the exponential function was selected as the cost model. Based on the above functions, a multi-objective optimization model was established. The NSGA-Ⅲ algorithm occurred, which can be used to optimize the tolerance allocation of the selected sequence, the optimal assembly sequence and the Pareto solution set of the multi-objective function. Finally, the auto-body floor can be used to illustrate the flowchart of tolerance allocation. The optimal solution is selected from the Pareto solution by the TOPSIS method. The results verify the feasibility and effectiveness of the proposed algorithm.