| 摘要 |
In a sheet metal member having a boss which is obtained by the method of the present invention, a cylindrical portion is formed at an outer peripheral edge, thereby allowing the member to be used as a pulley for a flat belt, a V belt or a poly-V belt. According to the present invention, when the boss is to be formed, the positional accuracies of portions other than the boss with respect to the boss are improved. The present invention includes: a boring step of opening a circular hole in a circular blank; a curving step of shaping the circular blank into a projected shape; and a bending step of restricting a radially outward spread of an outer peripheral edge portion of the circular blank which has undergone the curving step, and bending an inclined portion between the outer peripheral edge portion of the circular blank and the circular hole into a recessed shape, thereby forming the case-like boss. After the boring step and the curving step are conducted in an arbitrary order or the boring and curving steps are simultaneously conducted, the bending step is conducted while the circular hole is positioned to a reference position by a projection of a mold.
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