Self-tapping screw securing insulating plate - has cylindrical portion between head and thread accommodated inside plate

摘要

The self-tapping screw is partic. for securing insulating plates to a steel roof, having a head with a recess for engagement by a rotating tool, and a shank with a self-tapping thread screwing into the roof. Between the head (6) and the thread (8) there is a cylindrical portion (7) of a length to match the thickness of the insulating plates (4), and whose dia. is at the most equal to the internal dia. of the thread. There can be a taper portion joining the cylindrical one to the threaded one. The design avoids the risk of overtightening with the head pressing into the plate and thus causing leaks.