| 摘要 |
PURPOSE:To easily increase the height of a burring part, by executing spherical bending to a plate material first, subsequently, forming the burring part projectingly in the direction going toward the center of the spherical face, and also forming the circumference of the burring part like a plate. CONSTITUTION:First of all, a center hole 14 is pieced in a plate material 11 by a die 12 and a blanking punch 13. Subsequently, by a die 17 having a spherical recessed face and a punch 18 having a spherical projecting face, the plate 11 is bent into a spherical face. Also, the plate material 11 is set on a die 22 with its spherical face upwards, is pressed by a punch 23 so that a burring part 11a projects toward the center direction of the spherical face, and also the circumference of the burring part 11a is pressed into a plate, which becomes a collar part 11b. In the end, serration working is performed at the inside face of the burring part 11a, and gear punching is executed at the outside circumferential part of the collar part 11b, by which collar parts are obtained. |
