Screw fastens two flat panels together in building

摘要

The screw (1) has an elongated shank (2) with a protruding triangular-section thread (3) near the end remote from the head. The tip of the thread sweeps out a cone, very slightly increasing in diameter from the bottom end toward the head. The sharp point (11) of the screw is conical with one or more cutouts (13). The head (5) of the screw is flat with a very small thickness (S). There is a cruciform groove in the centre to accommodate e.g. a "Phillips" (RTM) screwdriver. The flat flange of the head is pierced with six equally-spaced holes.