A theoretical optimization method for drawbead restraining forces in automotive panel forming based on plastic flow principles

Aiming at improving the optimization efficiency, a theoretical optimization method for drawbead is proposed based on plastic flow principles. Essentially different from the existing common optimization methods which are on the basis of mathematics or statistics, this method, which can accurately reflect the relationship between the forming quality and the drawbead restraining force from the perspective of plastic flow theory, is a professional optimization method with higher efficiency. Plastic flow principles are first established to determine the influence degree of the drawbead restraining force to the forming quality. Then an evaluation model of the forming quality near a drawbead segment can be established based on the plastic flow principles to qualify the forming quality near the drawbead segment. Finally, a theoretical optimization method for drawbead is proposed based on the evaluation model, according to which the restraining force of each drawbead segment can be directly adjusted. By using the method, the optimal drawbead scheme in automotive panel forming can be obtained with only 3-5 iterations. The efficiency and accuracy of the optimization method are verified by a numerical example of a fender panel.