PURPOSE: To improve the accuracy of the outer diameter of a ring after forming, to prevent the generation of an underfill in a part of the cross section in the ring and to enable forming of the complicate cross sectional shape.
CONSTITUTION: An annular metallic mold 9 providing a circular inner peripheral side surface for press-forging the outer peripheral side surface of a ring blank W is arranged so as to be freely shifted in the horizontal direction and freely rotated. Then a metallic mold 9a for press-forming the outer peripheral side surface of the ring blank W into a prescribed cross sectional shape at the circular inner peripheral side surface of the annular metallic mold 9 is formed. A mandrel 12 for press-forging the inner peripheral side surface of the ring blank W is arranged so as to be freely lifted and rotated. Then a metallic mold 12a for press-forming the inner peripheral side surface of the ring blank W into a prescribed cross sectional shape at the circular outer peripheral side surface of the mandrel 12.
OKA EIICHI
AZUMA RYUICHIRO
