Improvements in or relating to Machines Adapted for Use in Forming Seams Between Portions of Sheet Material

1,164,613. Seaming non-metallic sheet material. BRITISH UNITED SHOE MACHINERY CO. 18 Nov., 1966 [19 Nov., 1965], No. 49143/65. Heading B5K. A machine for seaming together two pieces 28, 30 of material comprises two workpiece supports 23, 25, Fig. 5, disposed in side-by-side relationship facing the operator, each support 23, 25 being associated with means 22, 24 to assist the accurate location of a workpiece 28, 30 and with means to hold the workpiece 28, 30 on the support in its accurately located position; means to cause relative movement between the supports 18, 20 to bring together portions 19, 21 of the workpieces held thereon; and means to form a seam along the thus juxtaposed portions 19, 21. A machine for forming a welded seam along adjacent edge portions 19, 21 of two pieces 28, 30 of fabric coated with thermoplastic material, e.g. for forming a backseam in a shoe upper, comprises a stationary form 10 having curved side faces 12, 14 which meet in a curved ridge 16. The supports 23, 25 form part of clamp mechanisms 18, 20 and are pivoted on a vertical shaft 66, Figs. 1 and 6, secured to the form 10 to swing on to each side of the form 10 from positions in which they are spaced apart facing the operator. The supports 23, 25 have curved work-engaging surfaces 138, 138a. Clamp arms 37, 37a, Fig. 5, having thin rubber layers 130 thereon, are pivoted one on each side of the supports 23, 25 to hold the pieces 28, 30 in position with the marginal portions 19, 21 projecting beyond the supports 23, 25. Two gauge members 22, 24 are mounted to swing into engagement with the spread apart supports 23, 25 to assist in accurately locating the pieces 28, 30. Work-engaging surfaces 148, Fig. 1, of the members 22, 24 are also curved and are contiguous with the surfaces 138, 138a when in engagement therewith. Pins (150), (151), (150a), (151a), Fig. 3 (not shown), project from the surfaces 148. The form 10 which is earthed constitutes one electrode of high-frequency welding apparatus, the second electrode 177 of which is embedded in a rubber pad 170 on a vertically movable clamp assembly 26. Initially, the arms 37, 37a and the supports 23, 25 are held in their open positions, the members 22, 24 in their forward positions and the assembly 26 in its raised position. In operation, the pieces 28, 30 are positioned on the curved surfaces of the supports 23, 25 and the member 22, 24 with the curved edge portions 19, 21 lying against the pins (150), (151), (150a), (151a). Spr