| 摘要 |
PROBLEM TO BE SOLVED: To prevent a gypsum board from being excessively collapsed while assuring quick screwing operation and easily screw a self-drilling screw in the gypsum board vertically to the surface thereof in a self-drilling screw for tightening the gypsum board to a thin steel sheet-make frame member. SOLUTION: This screw comprises a shaft 1 and a head 2. A double-start thread part 6 having a first thread 4 and a second thread 5 and a single-start thread part 7 having only a first thread 4 are formed in the shaft 1. The end of the shaft 1 is formed in a converged part 3. Both threads 4, 5 are started from the converged part 3. When the screw is tightened, the first thread 4 is bitten into the frame member 13 at the single thread part 7. Since the double-start thread part 6 is positioned at the end, the gypsum board 12 is not excessively collapsed. The swelled part 13a of the frame member 13 is firmly hooked to the following flank of the first thread 4. COPYRIGHT: (C)2008,JPO&INPIT
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