METHOD FOR IRONING SPLINE TEETH IN PRESSED STEPPED SHEETMETAL AND SHEETMETAL CLUTCH DRUM FORMED BY SAME

摘要

In a method for forming spline teeth on the respective peripheral walls 1b and 1c of a press-formed sheet-metal article 1, on which a plurality of peripheral walls of different diameter are disposed in a continuous manner via a step portion 1a, by ironing and engaging a die 24 (28, 30) with a plurality of steps of ironing surfaces 28a and 30a, corresponding to the outer peripheries of pressed-formed article 1, and a punch having a plurality of ironing surfaces 32a and 34a, corresponding to the inner peripheral shape of press-formed article 1, in the axial direction, the punch is provided with a structure in which a first punch 32, for coacting with die 28 and thereby ironing the small-diameter peripheral wall 1b, and an outer peripheral punch 34, which is disposed at the outer periphery of punch 32, coacts with die 30 to iron large-diameter peripheral wall 1c, and descends to and stops at the position of step 29 of the die, are arranged in a split manner, and while small-diameter peripheral wall 1b is ironed after lowering first punch 32 and outer peripheral punch 34 integrally and ironing large-diameter peripheral wall 1c, in the process of ironing small-diameter peripheral wall 1b, the pressurizing force of outer peripheral punch 34 is made smaller than the pressurizing force for ironing so that small-diameter peripheral wall 1b will be elongated smoothly in the axial direction by the descending of (ironing by) first punch 32, thereby lessening the inflow of material into step portion 1a and preventing an excess thickness part to form on step portion 1a. IMAGE