Method and tool design for passive sheet metal hydroforming on conventional single action presses

Current sheet metal hydroforming processes require special equipment such as a hydroforming press with an external high pressure generator. This holds the barriers for entering the market high, especially for small and medium companies that cannot invest such an amount of money. In this article a method and tool design is presented that allows setting up a sheet metal hydroforming process on single action presses without using special hydroforming equipment. The inner pressure for forming the part is generated by tool integrated pistons and results from the difference between ram and cushion force in relation to the part's projected surface. To explore the limits of the process, a tryout tool was manufactured for producing test samples of medical parts in DX54D and AlMg3 0.6 mm. After the experiments, the parts were measured and analyzed to investigate the accuracy of the process, in comparison with the simulation done beforehand. This work will enable small and medium enterprises (SMEs) to produce small series hydroformed parts in a cost efficient way on their conventional presses.