| 摘要 |
PROBLEM TO BE SOLVED: To inseparably fix a bolt in a through hole without generating looseness while securing the slip torque and the loose force, and to restrict the generation of deformation of a flange while reducing a press-in margin. SOLUTION: A head of a bolt 12 to be pressed into a through hole 11 provided in a flange 10 is formed with at least two serration 14, 15 at a front side and a rear side in the axial direction. The front serration in relation to the bolt press-in direction is formed with an outer diameter to be pressed into the inner surface of the through hole with the predetermined press-in margin, and the rear serration in relation to the bolt press-in direction is formed with an outer diameter to be pressed into with the predetermined press-in margin smaller than that of the front serration. The rear serration is pressed into the inner surface of the through hole, of which diameter is shrunken by the spring back phenomenon of the inner surface of the through hole after passing the front serration while pressing it into the inner surface of the through hole.
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