Process design and experimental verification of hydroforming for flanged tubular part

摘要

Tube hydroforming is a technology that utilizes hydraulic pressure to form a tube into desired shapes inside die cavities. It is widely used in the automotive industry because of its various advantages, such as weight reduction, increased strength, improved quality, and reduced tooling cost. Hydroformed automotive parts used as structural components in the vehicle body frame or the subframe must often be structurally joined at certain locations, and it is useful if these parts can be manufactured with a localized attachment flange. This study proposes a flange hydroforming process, which consists of pre-bulging, flange forming, and conform shaping. The numerical process design by finite element (FE) analysis was performed with Dynaform 5.5. To accomplish a successful flange hydroforming process design, investigations on the proper combination of process parameters such as tool geometry, tube diameter, and internal hydraulic pressure were performed. To fabricate a flange of a specific target length on hydroformed tubular parts, an analytical model that predicts the flange length for a given set of process conditions is proposed. Hydroforming experiments to fabricate a flanged tubular part were performed, and the forming characteristics at various pressure conditions were analysed. The results show that the proposed hydroforming process can successfully produce flanged parts of a specific target length.