PURPOSE: To inexpensively manufacture V-pulleys which are excellent in dimensional accuracy, by forming a V-shaped groove through a rotary forming which uses a projected mold at the top and a recessed mold at the bottom and lateral rollers for forming U-shaped and V-shaped grooves, after a steel plate is formed to a stepped cylindrical body having a cuplike shape by pressing.
CONSTITUTION: A circular steel plate is obtained by blanking and the circular plate is pressed to a cylindrical body. Then, the cylindrical body is redrawn and formed to a cuplike shape. From the cuplike body, a stepped cylindrical body having a cuplike shape 3 provided with a disc part 4, a hub part 5 and a part 6 from which one side of the V-shpaed groove is formed in the following process, is formed. After a shaft hole and plural fitting holes are drilled in the disc part 4 and the surrounding area of the shaft hole, respectively, the cylindrical body 3 is put between a projected mold 27 at the top and a recessed mold 23 at the bottom, and both the molds are rotated while pressure is applied to them, and, at the same time, a U-shape groove 1 forming roller, and then, a V-shaped channel forming roller 37 is pushed into the space formed by the top mold and the bottom mold. Thus V-pulleys which are excellent in dimensional accuracy are formed easily.
MIURA KOUSUKE
NISHIDERA HIROYOSHI
