GB1452204A - Method of forming structural joints - Google Patents

Abstract

1452204 Structural bars; ladders R J REID 5 March 1974 [9 July 1973] 9947/74 Heading E1K and E1S [Also in Division F2] A joint between two elements, e.g. a rung 34 and a rail 10 of a ladder section, is formed by providing at least one flange 36 projecting from a face of one element and at least one elongate groove 14 on a face of the other element, the groove being of arcuate internal section and having a restricted opening 56 formed by lips 46, 48 allowing entry of the flange 36, after which pressure is applied between the two elements so that the flange deforms to form at least a portion of a coil within the groove, thus interlocking the elements. As shown, rail 10 has two grooves 14, 16 for receiving two flanges 36, 38 on the adjacent end of a box-section rung 34, the ends 62, 64 of the flanges being initially bent and rounded to provide a smooth initial engagement with the grooves. A machining process is preferably used to provide the flanges 36, 38 and at the same time to provide a tongue formation comprising a flat end face 74 and shaped side faces 115, 117 designed to fit tightly against corresponding surfaces 80, 116, 118 of the groove formation existing between the inner lips of the grooves 14, 16, when pressure is applied to tighten the joint assembly, as by pressing blocks (88-98, Figs. 4-6, not shown). Extension ladders. The ladder shown in Fig. 1 consists of two pairs of rails 10, 12, the rails 10 being connected as described above to the rungs 34 to form one ladder section and the rails 12 being similarly connected to shorter rungs 40 to form a second ladder section. Sliding engagement between the two ladder sections is effected by cooperating flanges 22, 30 on the rails 10, 12, respectively, the rear face 42 of each rail 12 at the same time sliding on the front faces of the rungs 34. Metal columns. A tapering metal column is constructed from four pieces 106, 108, 110, 112, Fig. 7, each identical prior to assembly and comprising a L section member one arm of which has a continuous groove at its outer edge and the other arm of which has a continuous flange, the grooves and flanges being similar to groove 14 and flange 36 of the ladder described above. The pieces are pressed together, first to form two U shaped members, and then to form the hollow column shown, such that the flanges are caused to deform to a progressively greater extent, and hence coil to a progressively greater degree, from one end of the column to the other, so as to produce the taper of the finished column.