SCREW OR BOLT WITH A RECESS IN THEIR HEAD AND DRIVER FOR ENGAGING THE RECESS AND METHOD FOR PRODUCING THE HEAD

摘要

A screw or bolt (1) with a recess (3) in a head (2) and a complimentary driver (20) for engaging the recess (3). The recess (3) comprises a plurality of lobes (4) flanked by driving flanges (5). Each flange (5) has an undercut portion (6). The floor (7) of the recess-lobes is inwardly inclined from their junctions with the top face (10) of the head (2) towards the longitudinal axis (X) of the screw or bolt (1). The complementary driver (20) has drive tip (23) with at least two drive elements (24). Each of the drive elements (24) is provided with a front face (27) and the front faces (27) are inclined from a point (29). The thickness of the portion (26) of the drive elements closest to the front faces (27) has an increasing thickness in the direction towards the front faces (27).