SCREW HAVING UNDERSIDE POCKETS

摘要

A self-countersinking, self-tapping screw has a head with a substantially flat underside that acts like a washer for bearing against a surface of a material into which the screw is inserted. On an underside of the head are one or more material-receiving pockets. These pockets receive material when the head of the screw bears against the surface. These pockets thus help lock the screw in place, i.e. help to prevent the screw from loosening over time. These pockets may have a circular or non-circular shape.