Dismantling screw with keyed head

摘要

The second keyed section (5) of the screw head is joined non-releasably to the remaining part (3,4) of the screw notably by a connector whose centre part (9) extending axially along the head exterior is adjoined by ends (9',10). The end (10) grips the second screw face furthest from the second head section from behind as against end (9') which grips the second section surface facing away from the first section (4). The centre part of the section (4,5) connector is formed from a sleeve or from several tongues spread round the head circumference. The connector end (10) is designed as a ring washer underpinning the head, and the second section of the head is rotatably enclosed by the connector along part of its axial extent. The outside diameter of the second section is reduced starting from a shoulder (7) forming the section face (5) and gripped by the connector and this tapered part has an external hexagon as compared with the inside hexagon fitted to the second section of the head.