Sheet metal member and method of manufacturing the member

摘要

According to the invention, an inward collar is integrally shaped on the inner periphery of a cylindrical boss portion. The inward collar is raisedly shaped in the axial direction on the inner periphery of the cylindrical boss portion by a top pattern tool having an ironing punch, and a bottom pattern tool having an ironing punch. The ironing process of forming the inward collar is repeated several times by using plural dies to finish the final shape.