PURPOSE: To form radial mounting pieces directly from one pipe and make the manufacture of the hub body easy by providing plural notches in parallel with the axial center to the both end parts of the pipe, expanding the notches by the use of plunger punches then bending the same.

CONSTITUTION: Notches 3 are provided to both sides of a blank pipe c to equally split the pipe c. This pipe c is fixed at the portion other than the portions provided with notches 3 and the notched portions 3 are expanded by plunger punches 5 having pressing faces 5a. Thence, the expanded portions are bent by pressing the plunger punches provided with the pressing faces rectangular to the axial center of the pipe c to form the mounting pieces protruding radially to the both end part circumferences of the pipe c.