板材多点成形中回弹的数值模拟及补偿研究

Research on Numerical Simulation and Compensation of Springback of the Multi-point Forming for Sheet Metal

回弹是板材多点成形中一个必须解决的问题。利用有限元软件LS-DYNA对板材冲压成形的回弹进行数值模拟,采用动态显式算法模拟板材成形过程,隐式算法模拟卸载回弹过程。对不同曲率半径、不同屈服强度的圆柱面成形件进行数值模拟,分析得出回弹趋势和回弹分布,提出通过修正基本体群成形面来补偿回弹的方法,并用B样条曲线拟合生成的曲面。经过两次补偿,成形件精度提高,证明该方法可以很好地补偿多点成形中的回弹。研究结果对于减小因回弹带来的误差,提高成形件的成形精度具有十分重要的意义。

Springback is a problem that must be solved in multi-point forming. Finite element software LS-DYNA was used to simulate sheet metal stamping spring, back. Dynamic-explicit algorithm was employed to analyze the forming processes and the implicit algorithm was used to analyze unloading processes. The springhack processes with different radius and different yield strength were simulated and the factors which had effect on the springhack were analyzed. A spring, back compensation method was proposed through modifying the forming surface of element group in the multi-point forming （MPF） by iterative ways and B-spline curve was used to fit surface. The accuracy of forming is improved after twice compensation. It is proved that this method can be used to compensate springhack of multi-point forming. The research results have much important meaning to reduce shape error which is leaded by plate springback and the accuracy of forming .is improved.