Electro Hydraulic Forming Process

 

 

 

Process principle

During electrohydraulic forming stored electric energy is suddenly discharged through a spark gap so that the surrounding working medium (e.g. water) is ionized and vaporizes, initiating a shockwave.

Process variants

According to the type of spark gap

• electrohydraulic forming with discharge through a wire (i.e. the electrodes are connected to each other by a wire bridge) and
• electrohydraulic forming with discharge through a gap (i.e. there is no connection between the electrodes) can be differentiated.

According to [Wil64], the setup with a wire bridge is more efficient and can be operated at lower voltages and longer distances between the electrodes, while in case of the setup with discharge through a gap, the process preparation is easier and faster.
The efficiency of an electrohydraulic process can be increased by using a suitable reflector. The reflector design needs to be done taking into account the specific forming task and considering that every redirection of the pressure war is related to energy losses. As shown in [Kle01], the shockwave can be focused by using an elliptic reflector geometry. Spherically spreading from the spark gap, which is positioned in the first focal point of the ellipse, the shockwave is reflected and converges in the second focal point. Other reflector geometries can be used for bulging tubes of different dimensions.