Abstract: 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.

Abstract: A metal tube is cold formed into a stamped member by filling the tube with a liquid change-of-state material, freezing the change-of-state material, sealing the tube containing the solid change-of-state material, and stamping the tube in a die. The change-of-state material compresses during the stamping step to force the walls of the tube to conform to the die cavity, eliminating the need to pressurize the tube prior or subsequent to stamping. Additionally, the solid within the tube provides support to the wall of the tube during a piercing step to form a hole in the tube having less deformation surrounding the hole than a comparative tube pierced without having the solid fill. After the stamping or piercing steps, the change-of-state material is melted and drained from the tube. Further, a tube is pierced by forming an outwardly bulged area and piercing the tube in the outwardly bulged area while simultaneously depressing the tube to substantially flatten the outwardly bulged area.

Abstract: A metal tube is cold formed into a stamped member by filling the tube with a liquid change-of-state material, freezing the change-of-state material, sealing the tube containing the solid change-of-state material, and stamping the tube in a die. The change-of-state material compresses during the stamping step to force the walls of the tube to conform to the die cavity, eliminating the need to pressurize the tube prior or subsequent to stamping. Additionally, the solid within the tube provides support to the wall of the tube during a piercing step to form a hole in the tube having less deformation surrounding the hole than a comparative tube pierced without having the solid fill. After the stamping or piercing steps, the change-of-state material is melted and drained from the tube. Further, a tube is pierced by forming an outwardly bulged area and piercing the tube in the outwardly bulged area while sinultaneously depressing the tube to substantially flatten the outwardly bulged area.

Abstract: A metal tube is cold formed into a stamped member by tube is cold formed into a stamped member by sealing a tube containing liquid at approximately atmospheric pressure and then stamping the liquid-filled tube in a die. The pressure within the tube increases during the stamping step to force the walls of the tube to conform to the die cavity, eliminating the need to pressurize the tube prior or subsequent to stamping.