METHOD OF STAMPING AND PIERCING A TUBE

摘要

A method for piercing a tube during liquid impact forming or hydroforming to form a hole with minimal deformation in the material surrounding the hole. The method includes the steps of: (1) filling the tube with liquid; (2) stamping the tube thereby increasing the pressure of the liquid within the tube; (3) piercing the tube while the pressure is elevated with a tapered punch whereby the material around the pierced hole is pushed back toward the die wall due to the elevated internal pressure of the tube; and (4) retracting the tapered punch from the tube with the face of the punch catching on the tube wall to pull the material back toward the die wall.