Hydroforming of unwelded metal sheets using active-elastic tools

Hydroforming of unwelded metal sheets is a forming process based on a pressurized hydraulic medium. This method is used for the production of complex and hollow sheet metal components. Sealing is achieved by applying a sufficiently high surface pressure, generated by the clamping force, between the blank holder and the flange area of the sheet metal part. The material flow during the high-pressure forming process substantially depends on the level of the surface pressure generated by the clamping force. Furthermore, sheet thickness variations in the flange zone influence the local surface pressure. The development of a new active-elastic tool system shows improvements concerning the material flow in the flange zone and reduced sheet thinning in critical work-piece areas. This paper provides an overview of the newly developed technology and shows recent results, especially in comparison to semi-rigid tools.