Abstract
In order to meet the current requirement of lightweight, energy conservation in car development, high strength steel (HSS) is widely applied. But too much springback and poor dimensional accuracy are fatal problems in the application of HSS, so precise predication of springback and an effective control method become urgent in the sheet metal forming area. In the previous study, we know that we can use Variable Blank Holder Force (VBHF) to decrease the springback. Therefore the VBHF approach is popular approach in industries, and it's important to design the VBHF trajectory. However, the information about how to optimize the VBHF Trajectory in previous study is limited. In this paper, we tried to develop an effective way to obtain the VBHF trajectory by using sequential approximate optimization (SAO) approach. The objective is taken as the minimization of springback. The constraints are quantitatively defined with the Forming Limit Diagram (FLD), in which no wrinkling and tearing can be observed. The design variables are the blank holder force. The Radial Basis Function (RBF) network is employed for the response surface, and the validity of the VBHF we obtained is examined through the numerical simulation.
