Patent ID: 7003995

Claim:
A hydrotapping power unit for powering a hydrotapping tool comprising a shaft adapted to advance and retract the tool with respect to a part while the part is contained in a hydroforming die cavity, a first powered device, a lead screw connection operatively connecting said first powered device and said shaft having a thread pitch equal to that of a thread-forming portion of the tool, a second powered device drivingly connected to said shaft and adapted to rotate said shaft in a forward direction and in cooperation with said lead screw connection advance said shaft and thereby the tool to a home position where a piercing end of the tool is located at least substantially flush with the die cavity during hydroforming of the part, said first powered device adapted to cooperate with said lead screw connection to further advance said shaft and thereby force the piercing end of the tool to pierce a hole in the part while hydroforming pressure is maintained in the part and thereafter continue to advance said shaft causing an extruding portion of the tool to enter the hole and inwardly extrude the part about the hole, a third powered device adapted to prevent shock loading on the tool during the piercing operation from reaching said lead screw connection, said second powered device operable to again rotate said shaft in said forward direction and in cooperation with said lead screw connection further advance the tool and thereby form a thread in the hole with the thread-forming portion of the tool, and said second powered device operable to rotate said shaft in a reverse direction and in cooperation with said lead screw connection retract the tool from the threaded hole at the same said feed rate.