Abstract: A sheet metal, elongate structural member is cold roll-formed from a strip of sheet metal no thicker than 1.2 mm, preferably 0.6 mm, including a central zone and two edge zones flanking the central zone and each having a free edge margin. The member includes a substantially planar web (9), a first hollow flange (10) extending along one edge of the web (9) and projecting laterally to both sides of the web, and a second hollow flange (11) extending along the other edge of the web (9) and projecting laterally to one side only of the web. The web (9) includes the central zone and the margins (17, 23) of the original strip secured flatly together by clinches (18, 29), and the hollow flanges are formed from the edge zones of the original strip excluding the margins thereof. The spacing of the clinches is selected so that the shear point of the member's section substantially coincides with the plane of the web.

Abstract: An impact drivable fastener, suitable for fastening sheet metal articles, includes a shank extending from a tip (10) at one end, which tip is adapted to be driven through a metal sheet, and a head (10) at the other end. A large pitch multi-start thread formation (11), including ribs separated by flutes, is formed on a part of the shank. The depth of the flutes and the height of the ribs increases uniformly from zero at the starting end of the formation nearer to the tip to maximum values at a position adjacent the head.