| Wrinkling, rupture and springback are common quality defects in sheet metal forming. Reasonable drawbead design can change the resistance distribution, which is one of the main means to reduce defects and control the forming quality. Traditional drawbead, whose cross section is single, is difficult to coordinate forming resistance of various parts and to overcome the stamping defects well. Non-uniform section drawbeads can control the quality of stamping better. However, it is difficult and critical to set up geometrical parameters of different sections. In this paper, based on previous studies, a method to set up geometrical parameters of non-uniform section drawbeads quickly is proposed. By using this method, the quantity of mold trials can be reduced.Thus, the development costs can be largly saved.The main work in this paper is concluded as follows.(1) The evaluation methods for wrinkling and rupture in sheet metal stamping were discussed. And the method based on FLD was selected to construct the objective function for rupture and wrinkling.(2) A simplify method was introduced to determine the resistance distribution of the non-uniform section drawbeads in this study. In this method, the equivalent resistance of the drawbeads was designated as the design variable, then the response surface was established through latin square experimental design and the most reasonable equivalent resistance distribution was optimized by multi-objective genetic algorithm. Finally, an example of the stamp forming was presented to illustrate the validity of the proposed method in practical projects.(3) The mathematical principles of the Stoughton model and the improved Weidemann model were described in this paper. The geometrical parameters of non-uniform section drawdeads were calculated by these two models, based on the known resistance distribution. Then, an example for stamping simulation of a true drawbead was given. A satisfied result was obtained. |
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