Patent ID: 7225541

Claim:
A method for forging a hollow rack bar from a blank pipe made of metal, comprising: (a) subjecting the blank pipe to a plastic deformation process for an adjustment of an inner diameter and an outer diameter of the blank pipe along an entire periphery of the blank pipe; (b) subjecting a predetermined outer part of the blank pipe to a flattening process to substantially flatten the predetermined outer part; (c) holding said blank pipe after the plastic deformation process and the flattening process by a die having a toothed portion so that the toothed portion is contacted with the predetermined outer part of the blank pipe; and (d) inserting, under a pressure, a mandrel into the blank pipe held by the die for causing the metal to be flown toward the toothed portion, thereby forming on the predetermined outer part of the blank pipe another toothed portion having a shape corresponding to a shape of the toothed portion of the die, wherein the step (a) for subjecting the blank pipe to the plastic deformation process comprises subjecting the blank pipe to a swaging process for reducing the outer diameter of the blank pipe, and subjecting the swaged blank pipe to an ironing process for producing a desired cross-sectional shape of the blank pipe.