Dynamic maintenance plan optimization of fixture components for a multistation autobody assembly process

Abstract

Process-oriented tolerance design and maintenance policy of the fixture system are major ways to ensure the dimension quality of autobodies. Traditional maintenance policy mostly uses a fixed threshold considering the static nominal process variables, which always lead to excessive or inadequate maintenance of fixtures. Based on the analysis of dynamic information in multistation assembly process, a maintenance policy optimization methodology is proposed to integrate the updated process states and monitored incoming parts’ deviations in the assembly process. In this method, the product quality constraint function considering dynamic fixture component degradation, dimension fluctuations of parts, etc. is constructed firstly, and then, a nonlinear optimization algorithm is used to obtain the optimal maintenance schedule with a minimum maintenance cost. An engine compartment assembly case was used to illustrate the procedure and advantages of the proposed method. At last, the effect of dynamic process variables and incoming parts’ qualities on the maintenance results were examined and discussed.