| 摘要 |
PROBLEM TO BE SOLVED: To provide a boss member of which no deflection occurs at a head part even if a recess is formed by rolling at the position contacting the head part of a shaft part. SOLUTION: The boss member comprises a shaft part 2, a head part 3 integral with the shaft part 2 and having a serration part 7 larger in diameter than the part 2 and a groove-like recess 5 on the outer periphery of the shaft part 2 contacting the head part 3. The outer periphery part of the head part larger than the shaft part in diameter and having a serration part 7 is formed inclinedly toward the shaft side in an umbrella shape, when the head part is forged. The recess 5 is rolled along the outer periphery of the shaft part 2 contacting the head part 3. Thus, the outer peripheral edge of the umbrella-like head part is formed flat together with the head part end face. Since the head part end face is a uniform flat surface against the surface of a work when the boss member is press-fitted, a gap is hard to occur between the work and the head part of the boss member, for tight contacting between them to assure action for rotation prevention and coming-off prevention. COPYRIGHT: (C)2007,JPO&INPIT
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