Patent ID: 7849724

Claim:
A method of manufacturing a ring-shaped member, comprising the steps of: molding an annular blank having a longitudinal extent with linear parts each forming an outer side, with a longitudinally extending hole forming inner sides, that face each other on both sides in a width direction of the annular blank, and curved parts at each longitudinal end for continuing both ends in the longitudinal direction of the linear parts, into an annular shape without rotation of the annular blank by: pressing said curved parts at both ends in the longitudinal direction toward each other; widening by pressing and energizing in a dimension in the width direction of the linear parts of the annular blank from the longitudinal hole; pressing and energizing the outer side of the curved parts towards the inner side of the curved parts into said longitudinal hole which dimension in the width direction is widened; and pressing the curved parts which are widened to a large curved part having a large curvature radius.