Patent ID: 7530251

Claim:
A method of fabricating an annular component part, the method comprising: preparing a circular piece of metallic raw material; forming a base bore in a radially center position of the circular piece; expanding the base bore of the circular piece to form an expanded bore in the circular piece while forming a cylindrical wall on a central area of the circular piece on one side thereof in a thickness direction such that the circular piece has a radially extending annular flange portion integrally contiguous with a root portion of the cylindrical wall; preprocessing an inner circumferential periphery of the cylindrical wall to form an annular stepped striation on the inner circumferential periphery of the cylindrical wall in an area in close proximity to the radially extending annular flange portion which serves as a deformation initiating point at which the cylindrical wall is initiated to deform radially inward; and squeezing the cylindrical wall on an outer circumferential periphery thereof causing a deformation to occur on the cylindrical wall at the deformation initiating point formed during the preprocessing step to form in the cylindrical wall a tapered profile thereby providing an annular body, wherein the cylindrical wall has an inner diameter gradually decreasing in diameter from the root portion of the cylindrical wall to be less than an open end of the cylindrical wall, and the squeezing step is executed with a tapered punch held in abutting engagement with the outer circumferential periphery of the cylindrical wall of the annual body.