| 摘要 |
A self-drilling screw (20) for use in steel houses has: a leg (11) with opposite end regions and having a screw thread (18) formed by the rolling method, one of the leg end regions being formed as a drilling portion (17), the other end region continuing to a flathead (12) through a neck (13) disposed close to the flathead. A recess (14) formed in the flathead (12) can engage a wrenching bit of a screw driver, and the recess has torque-receiving vanes (15) extending generally in parallel with an axis of the screw. The neck (13) is a thickened portion of the leg (11) to have a diameter larger than a diameter of valleys of the thread (18) and smaller than its outer diameter. The neck (13) extends between the top of flathead (12) and the inner ends (15a) of vanes (15), with the recess (14) having a conical bottom (16) disposed in the leg, so that the thinned head of self-drilling screw withstands a strong torque for tightening it and also protects the driver bit from "caming-out".
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