Warm Electrohydraulic Forming: A Novel High Speed Forming Process

Electrohydraulic forming (EHF) is one of the high speed forming processes for sheet metals which has considerable effect on formability improvement. In this process, the electrical energy stored in a bank of capacitors, discharges between a pair of electrodes submerged in a fluid and forms the sheet metal. The other interesting forming process which improves the formability of sheet metal is warm forming process where the blank is warmed and formed. In this study a patented hybrid process named warm electrohydraulic forming process (WEHF), which combines the electrohydraulic forming and warm forming processes is introduced and investigated numerically and experimentally. In this process the sheet metal is warmed and then formed by EHF. In WEHF, due to the fact that contact of the blank with water can prevent its warming, an air gap is created between the blank and water. To study this process, forming of aluminium alloy is performed using WEHF at elevated temperatures and compared with EHF and 23.6% increasing in failure strain is observed at WEHF in comparison with EHF. Therefore the formability improvement in WEHF process can be concluded in equi-biaxial strain condition.