Influence of pressure die's boosting on forming quality in bending process of thin-walled tube

Abstract

For large-diameter and thin-walled metal tubes, it is necessary to master the influence law of pressure die's boosting on forming quality during the cold-bending process. By introducing equivalent additional compressive stress in theoretical analysis, the wall thinning, springback and axial elongation analytical models under pressure die's boosting are established respectively, considering the effects of geometric and material intrinsic parameters. The influence law of boosting on forming quality is obtained. Finite element (FE) models are established to simulate the processes of tube bending and springback. The accuracy of FE numerical simulation results is verified by being compared with experimental results. By using FE simulation combined with physical experiments, underlying effects of the pressure die's boosting on bending quality are explored. The results show that the pressure die's boosting can effectively reduce the wall thickness reduction and the axial elongation of the bent tube, but the springback angle will increase significantly. The boosting force increases, the effect on forming quality will increase. The actual moving speed of the pressure die should be set to be slightly greater than the theoretical value to produce an effective boosting effect. These achievements are helpful to the design and optimization of the tube bending process.