Patent ID: 9003856
Filing Date: 2015-04-14
Classification: B21K

Abstract:
1. A method of manufacturing a flange structure including a first shaft portion, a second shaft portion, and a flange provided between the first shaft portion and the second shaft portion, the method comprising: forming a primary product by extending a columnar material in an axial direction by cold or warm forging such that the first shaft portion is formed at the first axial end of the material and the second shaft portion is formed at a second axial end of the material, the primary product forming step including: forming a secondary product by making a middle portion of the primary product overhang outwardly by cold or warm forging such that a first overhang having a thickness greater than a thickness of the flange is formed; forming a tertiary product by squeezing the first overhang by cold or warm forging such that a second overhang having an outline greater than an outline of the flange is formed, at least a part of an outer circumference of the first overhang being kept free from a constraint by a tertiary product die and a tertiary product punch while the second overhang is being formed; and defining an outer edge of the flange by cutting off an excessive portion of the second overhang, the excessive portion protruding outwardly from the outline of the flange.