Analysis and elimination fordrum warpage of U-shaped workpiece with super length and large opening of sheet metal

To study the mechanism of workpiece warpage under air-bending forming,a method combined experiment with numerical simulation is proposed in this paper.Through forming a semiellipse-shaped workpiece with super length and large opening,non-uniform springback processes for the formed workpiece are simulated by ABAQUS finite element platform.It is pointed out that large bending force and bed deformation of press brake can lead to warpage defect of workpiece.A technique used reverse deflection compensation for bed deformation of press brake and female die with large opening is found to eliminate warpage defect of workpiece.Manifested by the experiment for incremental air-bending forming of this workpiece,the method proposed yields satisfactory performance in improving forming accuracy and eliminating warpage defect of large workpicec.