GB910157A - Improved method of joining sheet members - Google Patents

Abstract

910,157. Sheet-metal joints. REYNOLDS METALS CO. July 25, 1961 [July 28, 1960], No. 26901/61. Class 83 (4). A method of joining sheet-metal members comprises the steps of displacing superimposed portions of the members to form a hollow protuberance, simultaneously shearing the opposed marginal edges of the protuberance so that opposite sides of said protuberance extend angularly toward the plane of the sheet members and terminate in the sheared edges and flattening said protuberance whereby said edges are caused to expand outwardly to overlap the adjacent portions of the sheet members. In an embodiment, the superimposed portions of a pair of aluminium sheets 10 and 12 are placed between a row of opposed interdigitating punches 14 and 16 which form a row of alternate upwardly and downwardly directed hollow protuberances 20 and 22, Fig. 3, each protuberance being separated by a longitudinal shear line 24. Each protuberance has a central arch 26 extending laterally of the sheets and semi-circular side panels 28 integral with the sheet members. The sloping sides of the arches 26 terminate in sheared marginal edges 30 which extend above the adjacent surface of the sheet member. To complete the joint the protuberances are flattened in two stages using a pair of finger dies 32 and 34, Fig. 5. The dies are arranged so that the fingers 36 of die 34 lie beneath the planar surface of die 32 while the planar surface of die 34 lies beneath the fingers of die 32. The die fingers are used to consecutively flatten first the top row of protuberances and then the bottom row of protuberances to form a joint as shown in Fig. 9 wherein the sheared edges 30 are expanded outwardly to form arcuate end flanges 124 extending beyond the adjacent shear lines to overlap adjacent fastening elements 120. The flattening operation imparts a slight corrugation to the fastening elements which stiffens the joint.