Patent ID: 8348572

Claim:
A hole-forming and thread-forming screw for screwing into a sheet piece, comprising: a screw head at one end of the screw for accommodating a tool, a threaded shank arranged below the screw head, a hole-forming part having a circular cross-section along an entire length thereof, the length extending directly from the threaded shank to a blunt end piece at an opposite end of the screw, the hole-forming part having a diameter (D 1 ) which gradually and steadily decreases in size from the upper end thereof, where diameter (D 1 ) is the largest, to the lower end thereof where the diameter (D 1 ) is the smallest, so that when the screw is viewed in a side view, the, hole-forming part can be seen to have outer sides with a continuous convex-shaped curve along the entire length thereof, extending from the threaded shank to the blunt end piece, and a plurality of rounded ribs running like threads are provided along at least a portion of the length of the hole-forming part, and the plurality of rounded ribs, which chiplessly displace material of the sheet piece, are situated symmetrically which respect to each other and have a pitch that is a multiple of a thread pitch of the threaded shank.