US Patent 9086088 Screw having underside cutters and pockets

A screw has a generally flat washer-like head. On an underside of the head are a plurality of cutters or cutting wedges arranged circumferentially around the shank of the screw. The cutters cut or carve off material when the screw is inserted into a fibrous material like wood to thereby facilitate countersinking of the screw head. The cutters may be triangular or quadrilateral wedges. One or more pockets are disposed radially inwardly of the cutters for receiving fibrous material to help lock the screw in place, i.e. to prevent the screw from loosening over time. These pockets may circularly shaped pockets disposed circumferentially around the shank. Alternatively, a single annular pocket may be provided around the shank.