| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw capable of holding even a plaster board having low strength and fixing the board firmly. SOLUTION: This screw is provided with a shaft 1 and a head 2, a first unit screw part 7 positioned on a tip side among screw parts formed on the shaft 1 is composed of two screw threads 4, 5 having different heights, and the second unit screw part 8 positioned on a head 2 side is composed of only one screw thread 4. The head 2 is constituted of a trumpet-shaped basic part 2a and a flange 2b overhanging from its terminal. The outside diameter of the basic part 2a is about double the maximum diameter (nominal diameter) of the screw part, and the maximum outside diameter of the flange 2b is set to be about 2.5 to 3 times the maximum diameter (nominal diameter) of the screw part. The plaster board 12 is held over its large area by the head 2 without being excessively crushed. For this reason, the plaster board 12 can be firmly fixed. COPYRIGHT: (C)2008,JPO&INPIT
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