Patent ID: 7257981

Claim:
A closed forging method for producing a forged product, which comprises: preparing a cylindrical cast ingot having a volume identical to a volume (V) of the forged product to be produced; placing the cylindrical cast ingot in a forging die; and applying pressure to a side surface of the cylindrical cast ingot; wherein a ratio of a thickness (T) of the cylindrical cast ingot to a diameter (R) of the cylindrical cast ingot is 1 or less, wherein the cylindrical cast ingot is placed in the forging die so that its thickness direction corresponds to a width direction of the forged product, and wherein the volume (V) of forged product, the thickness (T) of the cylindrical cast ingot, a longitudinal length (L) of the forged product and the diameter (R) of the cylindrical cast ingot satisfy the relation: (⅓)× L≦R =2×√( V/T π)≦ L.