Patent ID: 7487655

Claim:
A method for manufacturing a cylindrical ring with beads, comprising the steps of: disposing a metal mold adjacent to the outer circumference or the inner circumference of a closed metallic base ring, the metal mold having a molding face that faces the base ring and having grooves for forming the beads on the molding face along the circumferential direction; disposing a coil for electromagnetic forming at the opposite side of the metal mold such that the base ring is interposed therebetween; applying a momentary large current to the coil in this arrangement; deforming the base ring by pressing the base ring toward the molding face of the metal mold such that the base ring is molded into a shape corresponding to the molding face by electromagnetic forming, wherein an inner roll and an outer roll whose outer dimensions are finished with a required accuracy are prepared; and correcting the cylindrical ring with the beads molded into the shape corresponding to the molding face by electromagnetic forming by rotating the rolls while interposing the cylindrical ring between the inner roll and the outer roll.