Prediction and minimization of micro deformation on the automobile hood after dipping process

Abstract

During automobile dipping process, surface defects such as very small or micro deformation occurs intermittently on the assembled hood. The main cause of the surface defect is the location of hood supporting stay, structure of hood and pressure distribution resulted from fluid behavior in a paint pool. In order to minimize the defect, it is necessary to understand and predict the stiffness of the assembled hood as well as the fluid flow behavior in the paint pool, and the effects of locations of stays which are used in dipping process. This study has analyzed and simulated the micro deformation which occurs during dipping process. The difference between the measured and the computed stiffness of an assembled hood could be minimized by applying an equivalent material in the numerical model of assembled hood. It was found that the sequential application of fluid pressure to the hood structure in a painting pool was indispensable to obtain accuracy in the computation. By comparing the amounts of deformation which are measured in the actual process line with those of computation, the validity of the technique of computational fluid dynamics and technique of structural analysis have been confirmed. The optimal location of supporting stays to reduce the surface defects was given quantitatively with the coordinates.