A modified displacement adjustment method to compensate for surface deflections in the automobile exterior panels

Surface deflections are becoming more and more concerned by automotive manufacturers because these defects spoil the appearance of automobiles greatly. In this paper, a modified displacement adjustment (DA) method is proposed to compensate for surface deflections in the automobile exterior panels. The proposed modified DA method has two advantages. One is that it distinguishes the global deviation and the local deviation and is able to compensate for the local deviation (surface deflection) independently. The other feature is that the iterative scheme in the DA method is substituted with a compensation factor so that time-consuming iterations are reduced and the convergence problems caused by the small tolerance of surface deflection are avoided. In order to test the effectiveness of the proposed method, it is applied to compensate for surface deflections in a cylinder shallow shell part and a door handle part. The compensation results show that the proposed method is effective in reducing surface deflections in both parts. The work in this study provides a new method to reduce surface deflections by die design. For parts in which mechanical methods to increase the sheet tension during bending are not effective or suitable, the proposed modified displacement adjustment method is an effective alternative.