| 摘要 |
<p>This invention relates to a method of manufacturing a pulley of a sheet metal for V-belts without carrying out a cutting process which deteriorates the environment of a factory. A pulley (4) of a sheet metal for V-belts obtained by the manufacturing method according to the present invention has a plurality of valleys (31, 32) around which a V-belt is passed. In this pulley manufacturing method, an intermediate molded portion (3) is formed by forming a first annular V-shape-expanded valley (31) by slotting a root section (27) of a cylindrical portion (23) of a cylindrical material (2) of a sheet metal and an outer circumferential part (28) of a base section (23) continuous from the root section (27), and then axially stretching a cylindrical section (25), which is continuous from the first valley (31), while thinning the same an axially intermediate part of the cylindrical section (25) being pressed in the diametrical direction as an axial pressing force is applied to the cylindrical section (25) of the intermediate molded portion whereby the pressed part is bent in a recessed state to form a second valley (32). The stretching of the cylindrical portion of the cylindrical material of a sheet metal need not be done when the cylindrical portion is sufficiently long.</p> |
