| 摘要 |
PURPOSE:To simplify the working, and to form at a low cost many kinds of groove-shaped pulleys from a pipe blank material, by performing a rotational forming working to a pipe-shaped pulley forming blank material, and forming directly the pulley from the blank material. CONSTITUTION:A cylindrical pulley forming base material 2 is made by cutting a pipe-shaped blank material 1, and a port expanding forming such as a bulge working, etc., is executed to both end opening parts in accordance with necessity. This blank material 2 is set to a prescribed rotational forming dies, rotational forming roller for forming a pulley groove 3 is made to abut on the outside periphery of the peripheral wall and pressed against it, and also the rotational forming working is executed by applying a compressive force in the axial direction. Therefore, the working process can be simplified extremely, and also a ring-shaped pulley 4 having many kinds of groove diameters and groove shapes can be manufactured from the blank material 1.
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