| 摘要 |
PROBLEM TO BE SOLVED: To prevent overlapping of stress concentration portions by shifting an engagement starting position between an adjacent bolt and a female screw portion, when a plurality of parallel bolts are passed through through-holes and engaged with the female screw portion to fasten two members. SOLUTION: Through-holes 1a-1d of bolts 3a-3d are provided for a fastened member 1, screw holes 2a-2d engaging with the bolts 3a-3d are provided in parallel for a fastened member 2, the through-holes 1a-1d and the screw holes 2a-2d respectively have a same axis, and a member 1 is fastened with a member 2. Screw portion starting positions 4a and 4c of the bolts 3a and 3c are matched to a joining surface 5 between the members 1 and 2, the screw starting positions of the bolts 3b and 3d are positioned away from each other by two pitches of the screw, a distance Y1 below the adhering surface 5. Respective engagement starting positions of adjacent bolts 3a and 3b, 3b and 3c, and 3c and 3d are shifted from each other by the distance Y1, and stress concentrating at this position disperses in the progressing direction of the bolts 3a-3d to improve safety in strength.
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