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

TLDR: In this article, the effects of temperature and steel grade on the formability of the medium were investigated using the well known deep drawing steel DC04, and the results of the forming operations using this medium were presented.

Abstract: The need of lightweight construction for the body in white of modern cars increases due to legal restrictions of CO₂ emissions and the passenger s wishes of safety and low fuel consumption. On e 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 modem forming technologies, e.g. hydroforming with the po ssibility 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. Warm form ing operations can help to reduce the process forces and to increase form ability [1]. To combine the benefits of warm forming and hydroforming new forming media are necessary to overcome the problem of temperature stability of fluids, which is limited to about 350℃ [2]. Beside gases, which tend to leakage and which are highly compressible, granular material 1ike small ceramic beads can be used as a form ing medium. First results of forming operations using this medium were presented in [3]. The experimental tool used for those tests pressurizes the medium by a punch. To divide the effects caused by temperature and steel grade from the other effects experiments were carried out at room temperature using the well known deep drawing steel DC04. In fluences of the ceramic beads diameter, the number of repetitions, the punch geometry as the punch position, determining the volume of media, on the forming are presented.