Thickness Distribution in Conical Parts Formed by Hydroforming and Conventional Multistage Deep Drawing Processes

Abstract

Forming conical parts is one of the difficult fields in sheet metal forming processes. Because of low contact area of the sheet with the punch in the initial stages of forming, too much tension applied to the sheet that it causes bursting. Furthermore, since the major part of the sheet surface between the blank holder and punch tip is free, wrinkles appears on the wall of the drawn parts. These parts are normally formed in industry by processes such as spinning, explosive forming or multistage deep drawing. Hydroforming deep drawing is one of the special deep drawing processes which have been introduced in order to overcome some inherent problems in the conventional deep drawing with rigid tools. In the present work, an experimental program has been carried out to form and compare the forming pure copper conical-cylindrical cups by hydroforming and conventional multistage deep drawing processes. The conical parts in conventional deep drawing process formed in two stages. The results of the study demonstrate that thickness distribution are more uniform in the parts formed by hydroforming compared to conventional multi stages deep drawing processes.