Process for manufacturing ring-shaped member

Abstract

A yield which is a ratio of the weight of a ring-shaped member to that of a stock material, and a yield which is a ratio of the ring-shaped member to a blank are improved, and the cost is reduced. In a method of producing a ring-shaped member in which a ring-shaped member is obtained from a longitudinally elongated annular blank 3 , a pair of linking portions 3 b, 3 c are outward expanded from the inner side of the blank 3 , and a pair of arcuate portions 3 d are pressed from the outer side toward the inner side to be pressingly expanded, thereby shaping into a ring-shaped member.

1 . A method of producing a ring-shaped member in which a ring-shaped member is obtained from a longitudinally elongated annular blank having: a pair of arcuate portions which are opposed to each other in ends in a longitudinally elongated direction; and a pair of linking portions which are opposed to each other in both sides in lateral directions perpendicular to the longitudinally elongated direction, and which link together terminals of said pair of arcuate portions, wherein said pair of linking portions are outward expanded from an inner side of said blank, and said pair of arcuate portions are pressed from an outer side toward an inner side to be pressingly expanded, thereby shaping into a ring-shaped member.
 A method of producing a ring-shaped member in which a ring-shaped member is obtained from a longitudinally elongated annular blank having: a pair of arcuate portions which are opposed to each other in ends in a longitudinally elongated direction; and a pair of linking portions which are opposed to each other in both sides in lateral directions perpendicular to the longitudinally elongated direction, and which link together terminals of said pair of arcuate portions, wherein said pair of linking portions are outward expanded from an inner side of said blank, thereby shaping inflated linking portions, said pair of arcuate portions are pressed from an outer side toward an inner side to be pressingly expanded, thereby shaping enlarged arcuate portions having a radius of curvature which is larger than a radius of curvature of said arcuate portions, said pair of enlarged arcuate portions are then pressed from an outer side toward an inner side, thereby shaping enlarged arcuate portions having a radius of curvature which is larger than the radius of curvature of said enlarged arcuate portions, and, while restricting lateral outward expansion of said pair of inflated linking portions, said pair of inflated linking portions are shaped into inflated linking portions having a radius of curvature which is smaller than a radius of curvature of said inflated linking portions, thereby shaping into a ring-shaped member.