STEERING RACK AND METHOD OF MANUFACTURING THE SAME

摘要

When a punch is pressed down, the inner circumferential surface of a first rack blank bites into the upper surface of a second rack blank, and reaction in the process causes the material of the second rack blank to flow upward. This allows the material to be effectively used to form rack teeth, improving the degree of filling of a teeth form. Also, because a gap remains between the inner circumferential surface of the first rack blank and the outer circumferential surface of the second rack blank when the rack teeth forming is completed, dies are not sealed up. Accordingly, only a small forming load is required, so that the dies have an extended life. Further, because the upper surface of the second rack blank bites into the bore of the first rack blank to integrate the blanks together, the entire rack teeth formed has increased rigidity.