Influences on the Molding in Hydroforming Using Granular Material as a Medium

The need of lightweight construction for the body in white of modern cars increases due to legal restrictions of CO2 emissions and the passengers wishes of safety and low fuel consumption. One approach of lightweight construction is the use of high and ultra high strength steel, to reduce the weight of the single parts, another approach is the use of modern forming technologies, e.g. hydroforming with the possibility to create undercuts, to produce complex parts and thus to reduce the number of parts, the number of joining operations and the weight. The mentioned ultra high strength steels show a poor formability at room temperature and the necessary process forces are high compared to standard deep drawing steels. Warmforming operations can help to reduce the process forces and to increase form ability [1]. To combine the benefits of warmforming and hydroforming new forming media are necessary to overcome the problem of temperature stability of fluids, which is limited to about 350 °C [2]. Beside gases, ...