Screw and method of making same

摘要

A self-drilling self-tapping screw for use in fastening corrugated cladding to a support structure, is provided with a hole en larger 7 comprising axially extending ribs 8 for enlarging (e.g. by roaming) a hole already formed through the cladding by the drilling tip 3 of the screw. The hole enlarger 7 is positioned at or adjacent the junction between a threaded section 4 of the shank and a non-threaded section 5. The hole enlarger 7 ensures that the enlarged hole has a diameter no less than that of the non-threaded section 5 of the shank. The screw is formed by a method in which the thread is rolled, and the thread rolling die is modified so as to produce the hole enlarger 7 on the screw shank. The enlargement of the hole prevents damage to an anti-corrosion coating on the screw.