This process used the punch of the upper die to pierce billet for back cover,and the rest billet was used for front cover,which was deformed in the die with the strike of the press.

• 该工艺主要利用上模的凸模作为冲孔凸模,冲出的落料作为锻造后盖用,周围留下的材料则作为锻造环类锻件前挡用,该锻件在压力机的打击下在模具内成形。