基于NSGA-Ⅱ算法的车身薄板零件公差优化

Optimization of Auto-Body Sheet Metal Part Tolerance Based on NSGA-Ⅱ Algorithm

在汽车制造工业产品开发过程中,需要同时考虑质量与成本之间的矛盾。盲目提高质量要求,将使产品制造成本增加;随意降低成本,则有可能影响质量,导致客户投诉和返修率上升。首先建立概念设计阶段的装配偏差分析模型,用来分析车身装配质量;并选取指数函数作为公差成本函数,以此为基础建立多目标优化模型,然后采用NSGA-II算法优化各个零件的公差。最后利用车身侧围框架案例阐述零件公差分配过程,获得了多目标函数的Pareto解集,取得了较好的优化效果。

The contradiction of dimension quality and manufacturing cost should be considered during the process of developing automobile products.The manufacturing cost will be increased and the market competitivenss will be decreased if the quality requirement is improved blindly.Reducing cost at random may affect the quality,which may causes the increasing of complaint and repair rate.First the assembly quality of auto-body is analyzed by the assembly variation analysis model of concept design.Then the exponential function is used to establish cost-tolerance function.And a multi-objective model is established based on the above.Moreover,the tolerance of each part is optimized by NSGA-Ⅱ algorithm.Finally the auto-body side frame is used to illustrate the process of assembly allocation and the multi-objective Pareto optimal solution set is obtained.The results show that the algorithm can get good effects in optimizing part tolerance.