Patent GB-1269631-A (GB)
Title: Improvements in or relating to bonding or welding of workpieces by high electrical frequency heating
Inventor: WRIGHT MALCOLM EDWARD JOHN
IPC: B29C53/38
Filed: 1968-05-06
Abstract: 1,269,631. Seaming non-metallic sheet material. COX & WRIGHT Ltd. 29 April, 1969 [6 May, 1968], No. 21418/68. Heading B5K. In a method of welding or bonding twin seams at opposite sides of two flexible sheet workpieces by high frequency electrical heating, the work is placed in position, for the making of the first seam, on the front or top surface of a doublesided work-table 16, the work is clamped, and then the work-table 16 is turned to bring to the front or top its other work surface on to which the portions of the work to make the second seam are then placed and clamped by a second clamping means. The method is applicable to seaming two shoe parts A, B, Fig. 1, along their margins C, D with simultaneous folding of each part about a centre line E. The parts may be of heat sealable plastics material or of leather or synthetic leather with an adhesive printed on to the margins C, D. The work-table 16, Figs. 6 and 7, is mounted on a shaft 14 flanked by two sliding cam bars 15. The assembly 13 of the shaft 14 and the bars 15 is rotatable and axially slidable in a bearing 12 in. a frame 11. Work clamps 17, 18 are pivoted to the shaft 14 at 26 and each comprise a pair of spaced gripper fingers 19, 20 held off the associated table surface by springs 21. The tail of each clamp 17, 18 is provided with a roller 25 engaged by a ramp face 24 of one bar 15 acted on by a pneumatic cylinder 22 when it is desired to clamp the work. The assembly 13 is fast for rotation with but can slide axially relatively to a wheel 27 mounted in the bearing 12. The wheel 27 is toothed around three-quarters of its periphery and meshes with a rack 28 vertically reciprocable by a pneumatic cylinder 29. Welding heads 33 are each mounted on an electrically insulating block 34 carried by a plunger 32 slidable in a bearing 31 on a bracket 30. One terminal of a high frequency electrical supply source is connected to each head 33 and the other terminal is connected to the work-table 16. Springs 36 normally hold the heads 33 retracted. A head 38 on each plunger 32 is engaged by a lever 37 pivoted to the frame 11 at 39 and to links 40 which are pivoted to a bushing 41 slidable axially along the assembly 13. Pistonrods of a pair of cylinders 43, anchored to the brackets 30 at 44, are coupled to the bushing 41. In operation, the workpieces are positioned on the upper surface of the table 16 and the upper cylinder 22 is operated to cause the fingers 19 to grip the work. The cylinder 29 is operated to rotate the. assembly 13 and the table 16 through 180 degrees. The parts of the work to form the second seam are positioned on the second surface of the table 16 and the second cylinder 22 is operated to cause the fingers 20 to grip the work. The heads 33 are lowered by the cylinders 43 and, simultaneously, the bushing 41 travels rearwardly until it engages a shoulder 42 to retract the table 16, Fig. 9 (not shown). The two seams are simultaneously welded and the cylinders 43 are exhausted to raise the heads 33 and move the bushing 41 forwards until it contacts a shoulder 45 to project the table 16. The lamps 17, 18 are operated and the work removed.