Deformation behaviors of double-ridged rectangular H96 tube in rotary draw bending under different mandrel types

Abstract

Cross-sectional deformation is the most important formability assessment factor in rotary draw bending (RDB) of double-ridged rectangular tube (DRRT). Mandrel type influences the cross-sectional deformation directly. Due to the special cross-sectional shape of DRRT, the selection of right mandrel type becomes the most challenging task. Thus, a disconnect-type rigid mandrel and two kinds of PVC elastic mandrel were proposed. The influence of three mandrels proposed on the cross-sectional deformation of DRRT was investigated. The results show that (1) the type I mandrel can control the height deformation of flange preferably and the type III mandrel can control the deformation of distance between outer and inner ridge groove well. With respect to restraining the width deformation of DRRT, the two mandrels have their own merits. The performance of type II mandrel in preventing height deformation of DRRT is too poor to be used as a mandrel. (2) Only the type III mandrel is feasible when the mandrel support range is larger. Increasing the mandrel support range can decrease the height deformation obviously, but it has little effect on the width deformation. (3) When the size of DRRT is smaller, the type III mandrel can be a better option. However, when the size of DRRT increases, the height deformation of flange will increase evidently and the type I mandrel should be a better choice at this time.