Importance

Loading Importance Indicators...

Abstract

A screw of the self-drilling and self-tapping kind intended to be used in fastening corrugated or similar cladding to a support structure is disclosed. The screw shank is provided with a feature, such as, for example, a circumferential series of axially extending ribs, which is operable to enlarge (such as, for example, by means of a reaming process) a hole formed through the cladding by means of the drilling tip of the screw. The hole enlarging feature is positioned at or adjacent to the junction defined between a threaded section of the shank and a non-threaded section which extends from the screw head. The hole enlarging feature is arranged so as to ensure that the aforementioned hole, as enlarged, has a diameter which is not less than that of the non-threaded section of the shank. There is also disclosed a method of forming such a screw in which the thread is formed by means of a thread rolling operation, and the thread rolling die is modified so as to automatically produce the hole enlarging feature upon the screw shank during the course of the thread rolling operation.

Loading the Abstract Image...

First Claim