New die design for improvement of die corner filling in hydroforming of cylindrical stepped tubes

Abstract Seamless tubular components, such as stepped tubes, conical tubes, and box shape tubes, are produced mainly in the tube hydroforming process. In forming the components in this process, complete filling of the die corners and obtaining a sharp corner is very difficult or even impossible. In this paper, the die corner filling in hydroforming of cylindrical stepped tubes was improved by a new die set. The proposed die was simulated and the filling of the die cavity was investigated. In order to verify the simulation results, the new die set was manufactured and some experiments were performed. It is shown that by using the new die set the parts with sharp corners and with more uniform thickness distribution could be produced. The simplicity of the die and low internal pressure are further advantages.