| 摘要 |
PURPOSE: A flange forming method is provided to reduce the material cost since a sill portion is naturally formed on one side of a flange material even if a relatively thin flange material is used. CONSTITUTION: A flange forming method is as follows. An expanded portion(12) of an upper press die(10) has a diameter larger than the hole of a flange material(100), the peripheral portion(110b) of the hole of the flange material is pressurized by the expanded portion of the upper press die and a sill portion is projected from one side of the flange material(S1). The peripheral surface of the sill portion and the inner circumferential surface of the hole of the flange material are cut by a cutting tool and the flange is shaped.
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