中厚板U形冲压成形有限元模拟分析及回弹预测

Simulation analysis and springback prediction on U-shaped stamping of medium-thickness plate based on finite element simulation

采用有限元模拟,针对载重汽车用大梁钢中厚板在U形冲压成形中的回弹缺陷进行研究。首先,利用Numisheet2011给出的U形冲压标准考题对所建立的有限元模型进行验证,在此基础上对汽车用中厚板进行了成形性能模拟研究,并分析了控制回弹的措施。研究结果表明:与薄板相比,中厚板的回弹行为呈现出明显差异,其冲压后上圆角上端区域出现局部增厚,而且侧壁纵截面等部位的弹性应变分布特点使得板料出现负回弹,侧壁曲线对应圆弧半径较大,同时U形件内侧侧壁出现两个应力集中点;此外,由于板料较厚,成形结构件的内外侧Mises等效应力分布表现出较大的差异。针对中厚板冲压成形可能出现的负回弹缺陷,提出采用模具回弹角补偿和增大凹凸模间隙两种方法来减小中厚板的回弹量,从而得到了较为良好的最终板形。

The springback defect during U-shaped stamping process for medium-thickness plate used as large beam steel of heavy truck was studied by finite element simulation.First,the established finite element model was verified by the U-shaped stamping standard test examples given by Numisheet2011.On this basis,a simulation study on the formability of medium-thickness plate for automobile was carried out,and the measures to control the springback were analyzed.The results show that the springback behavior of medium-thickness plate is significant different from that of thin plate,and an obvious local thickness increase emerges around the upper area of upper corner after stamping.Moreover,the elastic strain distribution characteristics on the longitudinal section of sidewall and other parts make the plate material appear negative springback,and the curve of sidewall corresponds to a larger arc radius.At the same time,two stress concentration points appear on the inner sidewall of the U-shaped part,and due to the thicker plate material,the Mises equivalent stress distributions on the inner and outer of the formed part also show significant differences.To avoid the negative springback defect in the stamping of medium-thickness plate,two methods of die springback angle compensation and increasing the clearance between punch and die are used to reduce the springback amount of medium-thickness plate,so as to obtain a better final plate shape.