Patent ID: 7036348

Claim:
A method of forming an annular rolled reinforcing rib between a central panel and a chuckwall of an end shell in a single stroke and at a single station of a double action press prior to the removal of the shell from the press, comprising the steps of: blanking and drawing a disc blank having a central panel and an outer flange by wiping the periphery of the disc blank over an inner die core ring; forming a chuckwall by advancing a punch core and clamping a portion of the central panel against a die core; clamping a portion of the chuckwall between an inner pressure sleeve and the die core ring; providing an annular void between the punch core and die core ring when the punch core clamps the central panel against the die core; forming the rolled reinforcing rib from an unclamped portion of the chuckwall within the annular void by advancing the inner and outer pressure sleeves while maintaining clamping engagement of the central panel between the punch core and die core, and between the inner pressure sleeve and die core ring; and releasing said clamping engagement substantially simultaneously between the punch core and die core and between the inner pressure sleeve and die core ring after forming the reinforcing rib.