Method of Manufactring Ring-Shaped Member

Abstract

The yield rate or the percentage of the weight of the ring-shaped member with respect to the weight of the raw material and the yield rate or the percentage of the ring-shaped member with respect to the blank are improved to achieve the cost reduction. A half-finished article 18 having large curved parts 3 D obtained by widening the curved parts 3 d so as to have a curvature radius larger than the initial curvature radius, and bulge-out parts 3 E curved to a circular arc shape at a curvature radius larger than the curvature radius of the curved parts 3 d at the linear parts 3 b , 3 c is molded, and thereafter, the half-finished article 18 is molded into an annular shape to obtain the ring-shaped member 1.

1 . A method of manufacturing a ring-shaped member in which an annular ring-shaped member is obtained from a longitudinal annular blank having curved parts at both ends in a longitudinal direction, wherein
 the longitudinal annular blank is molded into a half-finished article having a pair of large curved parts widened so as to have a curvature radius larger than the curvature radius of the curved parts and a pair of bulge-out parts curved to a circular arc shape at a curvature radius larger than the curvature radius of the curved parts, and thereafter, the half-finished article is molded into the annular ring-shaped member.   
   
   
       2 . A method of manufacturing a ring-shaped member in which an annular ring-shaped member is obtained from a longitudinal annular blank, wherein
 the longitudinal annular blank has linear parts facing each other at both sides in the width direction and a pair of curved parts for continuing both ends in the longitudinal direction of the linear parts; and   the blank is molded into a blank having a dimension in the width direction widened from the dimension in the width direction of the blank by widening the linear parts outward in the width direction, the blank whose dimension in the width direction is widened is molded into a half-finished article having a pair of large curved parts obtained by widening the curved parts so as to have a curvature radius larger than the initial curvature radius and a pair of bulge-out parts curved into a circular arc shape at a curvature radius larger than the curvature radius of the curved parts at the linear parts, and thereafter, the half-finished article is molded into the annular ring-shaped member.