SCREW WITH COUNTERSUNK HEAD Russian patent published in 2012 - IPC F16B35/06 

FIELD: construction.

SUBSTANCE: countersunk head of a screw with a lower side, which has at least one support surface or a face, and at least one groove. The support surface or the face forms a part of the rotation surface around the screw axis and is made as capable to adjoin the countersunk surface of the attached element having the appropriate contour. The groove at its rear end, in direction of screwing the screw with the countersunk head, is limited with a cutting edge. In direction of screwing in front of the support surface there is a front surface that adjoins it and is inclined in radial direction inside. At its free end the front surface has the cutting edge, which along its length preserves the distance in radial direction inside from the rotation surface.

EFFECT: invention makes it possible to avoid damage of the countersunk surface with cutting edges during screwing.

10 cl, 9 dwg