Optimal Parameter Study of the External Inverting Die

Abstract

In the external inverting process of thin-walled circular tube, buckling instability often occurs in the straight line section of thin-walled tube due to the size mismatching of forming die. Based on LS-DYNA971, the finite element modeling was built up and a series of simulation calculations were conducted about the external inverting process of thin-walled circular tubes on two circular arc dies under axial compression. The inverting plastic deformation of a Q235 steel thin-walled tube with an outer diameter of 60mm and a wall thickness of 2mm was reproduced on two die types with different fillet radii. The simulation results show that the optimal induced fillet radii of the dies is 10.7±0.1m, and meanwhile the thin-walled tube head has good formability in the early stage, which is convenient for the subsequent shape operation of the invertube. This paper provides a method reference for the die structure design used for inverting the thin-walled tube.