Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Hydroforming of sheet metal pairs: modelization, process layout and process control



Datum: 07.09.1999


Author


Reporter

  • Prof. Dr.-Ing. Dr.h.c. M. Geiger
  • Prof. Dr.-Ing. K. Roll, Stuttgart

The hydroforming of sheet metal pairs is a new process that will find its applications in the production of structural components of car bodies-in-white. In this process, the two blanks are deformed simultaneously by a pressurized fluid which is injected in the hollow space between them, while the rims of the blanks are kept tight. The target of the research was to develop a profound knowledge of the effects influencing the process and to provide the fundamentals for future industrial applications. The process has been modelled analytically and in finite element analysis to identify the main influencing parameters. Special attention has been devoted to the coupling of the deformations of the two blanks which can be welded together or not. The process limits (loss of tightness, bursting) and characteristic curves (e.g. clamping curve), which have been determined theoretically and experimentally, have been brought together in a process window that can be used for the process layout. Finally, process control strategies have been developed and verified in order to obtain an optimal process efficiency. This included the search for optimal load paths and the implementation of closed-loop control mechanisms for the distribution of blank-holder pressures.