为了进一步控制先进高强钢在冲压成形中的回弹问题,提出了一种无需增大材料成形裕度、通过伺服液压设备增大可变闭合力降低回弹的方法.对冲压成形的1 180 MPa双相钢U形基准零件,利用有限元分析增大可变闭合力控制回弹的可行性,并进行试验验证,从残余应力和位错角度研究增大可变闭合力减小回弹的机理.结果表明:该方法使成形后的材料表面残余应力减小,位错密度降低,从而使非弹性回复增加,达到减小目标零件22.3%的回弹角度效果.由于该方法仅在零件成形瞬间施加,不影响材料成形过程中的塑性流动,所以无需增加额外的材料成形能力和整形工序,改变生产节拍即可应用于实际工业,具有广阔应用前景.

In order to further control the springback of advanced high-strength steel in stamping,a method to reduce the bending springback by increasing the variable closing pressure (VCP) through servo hydraulic equipment without increasing the material forming margin was proposed. For U-shaped benchmark parts of 1 180 MPa dual-phase (DP1180) steel formed by stamping, the feasibility of increasing VCP to control springback was analyzed by using the finite element method, and the mechanism of increasing VCP to reduce springback was studied from the perspective of residual stress and dislocation. The results show that the proposed method can reduce the residual stress and the dislocation density of the formed material, thus increasing the inelastic recovery and achieving the effect of reducing the springback angle of the target part by 22.3%. Because this method is only applied at the end of part forming, which does not affect the plastic flow in the material forming process, there is no need to increase the additional material forming ability and shaping process, which can be applied to actual industry without changing the production rhythm, and has a broad application prospect.