Patent ID: 7047787
Filing Date: 2006-05-23
Classification: B21D,B21K

Abstract:
1. A method of forming a spline in a boss of a sheet metal-made rotary member which comprises the boss and a peripheral portion in an outer periphery of the boss, and in which an annular excess portion that protrudes in one axial direction of the boss is disposed between the boss and the peripheral portion, and a root portion of the boss and the peripheral portion are displaced in the axial direction of the boss, the method comprising the steps of: passing a spline forming a male mold through the boss of the sheet metal-made rotary member, the boss being fitted into a boss fitting hole of a rotary member holding mold to hold the sheet metal-made rotary member holding mold to hold the sheet metal-made rotary member to the rotary member holding mold in a state where the annular excess portion separates from a holding face; and impelling a pressing mold toward the rotary member holding mold to press the annular excess portion against the holding face of the rotary member holding mold, and the root portion of the boss is squeezed against the spline forming male mold to be plastically deformed, while the annular excess portion is clamped between a pressing face of the pressing mold and the holding face of the rotary member holding mold to be deformed into a flat shape, whereby a boss spline is formed in the root portion of the boss.