Method of manufacturing multi-grooved V pulley

摘要

In forming a multi-grooved V pulley by roll forming, a preliminary forming method is disclosed for preventing the occurrence of a top roll accompanied by a crack along each annular ridge of the pulley. A preliminary form roller is pressed against an annular material to fabricate a preliminary form having, in a sectional view, a corrugation including linear flat root portions and ridges alternating with them on the bottom surface of a wide annular groove. Next, a finish form roller having a plurality of annular V-shaped protrusions is pressed against the linear flat root portions of the preliminary form to thereby finish roll the preliminary form. The forward end of each V-shaped protrusion is kept off from the slopes of the corrugation ridges, and therefore is not broken under a bending moment.