Hydroforging of Thick-Walled Hollow Aluminum Profiles

Abstract

Lightweight design of cars is one way to reduce fuel consumption and increase the range of cars. This is an important factor to attain the EU limit values for CO2 emissions for vehicles and so to escape penalties for exceeding these limits as of the year 2012. The increasing uses of high-strength steels or of lightweight structures are adequate means to reducing weight. At IPH – Institut für Integrierte Produktion Hannover gGmbH a method to produce hollow profiles made of aluminum was developed. The method combines flashless forging and tube hydroforming. This is called hydroforging. With this method it is possible to produce thick-walled hollow aluminum profiles with undercuts without complex tool kinematics. The forging is supported by an active medium. A tool concept has been developed that uses the drives of a hydraulic press with die cushion. With this tool various component geometries were produced and analysed. To produce the tools interior pressure and the forming pressure liquid tin as incompressible active medium was used. The forming is initiated by an upsetting of the aluminum profiles and supported by the active medium, so that the profile is pushed against the engraving of the dies. The process was designed based on simulations and verified by practical experiments. This paper describes the development of the forging process with active medium and the discussion of the forging experiment results.