PUNCH HAVING DEFORMATION-PREVENTIVE FUNCTION FOR RING WITH FLANGE

PROBLEM TO BE SOLVED: To provide a punch for preventing the fall-down inward the center of an inner diameter surface at the rear part of a ring, at the time of taking out a thin plate in the center part of inner diameter of the ring with the punch, when the ring with a flange is forged from a large diameter round bar steel piece. SOLUTION: In the forging process for ring 8 with the flange having flange 8a, the punch 1 used for removing the punching waste in the thin plate 8c formed with the forging-press on the inner diameter surface of the ring 8 with flange, is formed of a split punch consisting of a hole-opening punch 2 and a pushing-in punch 3 set at the rear part. A deformation-preventive guide 4 which can move the outer peripheral surface of the hole-opening punch 2 and has an outer peripheral surface outline part 4a, wherein the outer peripheral surface outline part 4a at the tip side is abutted on an inner peripheral outline part 8e for bearing at the rear part of the punching waste removing part 8d in the ring, is arranged, and on the inside of the pushing-in punch 3 facing the deformation-preventive guide 4, a pin hole 5 is annularly arranged, and elastic springs 6 and pushing-in pins 7 are movably incorporated in the pin holes 5. COPYRIGHT: (C)2007,JPO&INPIT