| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-yield method of manufacturing an annular member of which a degree of freedom of a dimension is high.SOLUTION: A method comprises an expansion step of radially expanding an annular raised wall 91 having an opening part 910 on one end in an axial direction so as to make a shape of the opening part 910 viewed from the axial direction close to a perfect circle. Before the expansion step, the opening part 910 has a shape except for a perfect circle shape when viewed from the axial direction of the annular raised wall 91. Therefore, as compared with a case that the opening part 910 has the perfect circle shape when viewed from the axial direction of the annular raised wall 91, a degree of freedom of arrangement of the annular raised wall 91 on a plate material (a plate material as material of the annular member) can be increased. Thus, an occupied area of the annular raised wall 91 on the plate material can be increased. That is, many annular members can be manufactured from one plate material. |
