Increase of Process Stability of Sheet Metal Hydroforming due to Feed Back Control

Sheet metal hydroforming of single sheets is a deep drawing process. In contrast to deep drawing with rigid tools, an active fluid medium performs the forming operation. The process is chiefly influenced by the control of the clamping force against the increasing fluid pressure. Although the optimum force‐pressure progression is close to the sealing line, it is initially unknown and dependent on different system parameters. To perform the process at the ideal curve, the system parameters need to be detected online and led back to the feed back control unit. An optical system is used for the detection of the sealing state. The detection system is a CCD‐camera system that allows for the continuous recording of occurring leakages. Acquired data permit the application of different strategies to control the forming process along the sealing line. This paper provides an overview of this developed technology, advantages and problems with regard to the process stability and performance, the parts quality, and recent results comparing control strategies.