A numerical analysis on microtube hydroforging

Abstract

High-pressure tube hydroforming is a promising method to deform the tubes in various shapes by bulging the tube by applying high internal pressure. However, the challenges lie in the process itself, i.e., requires an expensive pump system and brings excessive thinning in the deformed part section. One option is to reduce the required pressure to solve these difficulties, and the other is to provide the axial feed to the tube in the deformation zone to reduce the thinning. However, due to the higher axial load, the tube buckles. This study is taking advantage of this buckling mechanic to convert it into a successful shaping option. This process is named as tube hydroforging. In this process, the tube was first bulged to a level using internal pressure in an open die without axial feed. Then a minimum pressure was applied, and dies were displaced to shape the tube. The paper studies the process for the microtube. The results noted that lower internal pressure is required to bulge the tube and either no internal or a minimum constant pressure to hydroforge the tube depending on the opening section and thickness of the tube.

Deformation behavior of advanced high strength steel with different strain hardening exponents during tube hydroforging

“…Similar studies on material flow during plastic deformation while considering the geometrical parameters show the influence of shaping due to axial compression. [6][7][8][9][10][11] The geometry of the tube is important to determine the displacement due to axial compression the tube will be able to withstand. 6 The tube thickness is primarily the most important geometric feature that determines how walls will form and how much pressure is required to initiate plastic deformation in the tube.…”

“…9 The die spacing affects the force that is required to forge and affects the thinning ratio for the tube. 10 Hydroforging is also used to deform the tube to non-circular shapes and how the axial displacement affects the shaping. 11 However, there are limited literature 12,13 showing the effect of the strain hardening exponent on the deformation behavior during hydroforging.…”