| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent the deformation of a cap at the time of a mounting process by arranging a reinforcing element on a surface where a rivet part faces a direction separated from the lower surface of a rivet flange. SOLUTION: This reinforcing bead is provided with a first side part 28 folded back outward in the radial direction from the inner boundary line of the rivet flange 24 and a second side part 30 folded back inward in the radial direction from it and continuing to a nearly circular/cylindrical rivet axis 22. The upper surface 28a of the part 28 is flatly abutted on the lower surface 25 of the flange 24 and the upper surface 30a of the part 30 is flatly abutted on the lower surface 28b of the part 28 to make a rear surface supporting area supporting a cap 10. At the time of a mounting process, the inner surface 18 of the cap 10 is pressed to the flange 24 by the pressurizing force of a rivet tool to the upper surface 14 of the cap 10. However, a reinforcing element 26 especially prevents the flange 24 from bending downward in an area where the axis 22 is brought in contact with the flange 24 and a track is not left in the cap. |
