screw

Abstract

A screw includes a head, a shank extending from the head along an axis, a pointed tail formed at one end of the shank opposite the head and radially tapering away from the shank, a main thread spirally disposed on the shank, a drilling thread spirally disposed on the pointed tail, and at least one buffer thread formed on at least one of the shank and the pointed tail. The main thread has an upper tooth surface and a lower tooth surface at a predetermined angle to the upper tooth surface. The drilling thread has a lower tooth height away from the axis than the main thread. The buffer thread has a first tooth surface facing one side of the head and a second tooth surface at an operating angle greater than the predetermined angle to the first tooth surface.

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