Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Simulation Based Process Design for the Hydroforming of Sheet Metal Pairs



Datum: 19.12.2000


Author


Reporter

  • Prof. Dr.-Ing. M. Geiger
  • Prof. Dr.-Ing. K. Roll, Daimler Chrysler AG

When hydroforming sheet metal pairs, two initially flat sheets are formed to a hollow body by the means of an acting pressure and a surrounding tooling. The goal of the conducted work is to improve the knowledge for producing a defect-free variety of stiff and complex shaped parts for mainly automotive applications. Features of a complex part include a non flat blankholder surface as wells as a part branch. In order to examine the process specific part defects a complex shaped part was designed, examined and manufactured. Defects like bursting and tearing are well known from other sheet metal forming processes and were also detected when hydroforming sheets. In addition to these defects specific wrinkling can occur depending on the part geometry i.e. the blankholder surface. When using a non flat blankholder, the sheets are pre-formed by closing the tooling. Increasing the pressure can then cause wrinkling due to the pre-form. With the help of numeric simulations and experiments, different process strategies were developed to inhibit the wrinkling. A purposefully optimized blankholder control was applied in the experiments and confirmed the conducted simulations. The results show that optimized process strategies help to avoid process specific defects like wrinkling.