| 摘要 |
PROBLEM TO BE SOLVED: To prevent the loosening of a screw for holding and fixing a waterproof sheet and a heat insulating material for a roof of a building. SOLUTION: The fastener comprises the screw 1 having a drill part 5 and the disk-like washer 2. A seat face of a head 4 of the screw 1 is formed into a tapered shape, and a plurality of protrusions 9 extending in a radiation direction are formed with equal spaces between each other. A seat receiving part 10 of the washer 2 is divided by a plurality of tongue pieces 14 corresponding to the protrusions 9. The tongue pieces 14 are twisted so that an advancing side end face 14a is positioned on the inner side of a radius. The washer 2 closely contacts a work 16 with large friction, and, in that state, by the protrusions 9 of the screw 1 abutting the tongue pieces 14 of the washer 2, reverse rotation (loosening) of the screw 1 is prevented. COPYRIGHT: (C)2007,JPO&INPIT
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