PURPOSE:To realize the shortening of a manufacturing stage and its high accuracy by forming a V groove using a V groove forming roller die on this rim face after forming the rim on a disk outer periphery by rotating the both by pressing the roller dies in an uneven arc shape at its outer peripheral end face to the outer peripheral end face of a metal made disk. CONSTITUTION:The uneven arc shaped pressing face 9 of roller dies 10 is pressed to the outer peripheral end part of a metal made disk 1 and the both are rotated. The outer peripheral part of the disk 1 is thus extruded symmetrically to both faces and a rim 13 is formed. The outer peripheral face of this rim 13 attains to the V groove forming face in thinner shape compared with both sides at its center. Plural V grooves 18 are then formed on the V groove forming face by rotating a V groove forming roller die 16 with its pressing to this V groove forming face. Since both sides of the rim 13 become thick on the B groove forming face the flow of the metal to the center from both sides can be made smoothly at the V groove forming time, the state of an underfil at both sides is not caused as well and the pulley of high accuracy having a uniform V groove is obtd.
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