Patent ID: 7673487

Claim:
A method for forming a hollow shaft having a flange portion at an end thereof in sheet metal, the method comprising: forming a circular preparatory opening in a region of a surface of the sheet metal to which a burring punch is to be contacted; forming, from the preparatory opening, a cylindrical portion which is open at both ends and upright with respect to the surface of the sheet metal by using the burring punch and a burring die; and bending outward a free end portion of the cylindrical portion, so as to form an upright portion protruding upright with respect to the surface and a flange portion radially extending from an end of the cylindrical portion with respect to a central axis of the cylindrical portion by using a bending punch and a bending die, the free end portion bending including: bending outward the free end portion of the cylindrical portion so as to form, with respect to the cylindrical portion, an intermediate angle of less than 90°; and further bending outward the free end portion of the cylindrical portion so as to form an angle of substantially 90° with respect to the cylindrical portion, thereby forming the flange portion, wherein throughout the bending, the bending die is partially contacted to a lateral surface of the upright portion to prevent deformation of the lateral surface.