多点拉形数值模拟及模具型面补偿方法

建立了板料多点拉形有限元模型,确立了用于动态显式算法的拉形加载模式,并应用到典型件的拉形过程数值模拟中。对马鞍形曲面件的多点拉形进行了数值模拟,探讨了成形件上应力、厚度等的分布规律以及回弹和弹性垫的不均匀变形对成形件精度的影响。模拟结果表明,成形件的应力、厚度分布均匀,卸载回弹很小,弹性垫的不均匀变形对成形件精度的影响比回弹要大;为获得精确形状的成形件,提出了一种基于数值模拟结果通过反复修正获得准确的多点拉形模具型面来补偿多点拉形中弹性垫的不均匀变形和回弹的方法。

Numerical simulation of sheet metal multi-point stretch forming and compensation of die surface

A finite element model was built for the sheet metal multi-point stretch forming(MPSF),its loading mode for the dynamic explicit algorithm was proposed,and the model was applied to the MPSF of a typical part.The numerical simulation of the MPSF for a saddle surface workpiece was performed.The distributions of stress and thickness in the formed workpiece and the effects of the springback after unloading and the non-uniform deformation of the elastic cushion on the precision of the formed workpiece were investigated.The simulation results show that the distributions of stress and thickness in the MPSF workpiece are uniform,the amount of springback after unloading is small,the effect of the non-uniform deformation of the elastic cushion on the precision of the MPSF workpiece is larger than that of the springback.A method based on the iterative corrections according to the numerical simulation results was proposed to compensate the non-uniform deformation of elastic cushion and the springback to enhance the accuracy of MPSF.