| 摘要 |
1312525 Seaming non-metallic sheet material M CAVANNA 26 June 1970 [4 July 1969] 31067/70 Heading B5K [Also in Division B8] Thermoplastic film layers 11 are welded by passing the contacting layers between two pairs of endless belts 6, 7, the belts of each pair being arranged one above the other with a space therebetween equal to the required width of the weld, the facing runs of the belts being parallel, and blowing hot air by at least one nozzle 17 or 18 into the space between the belts of each pair. Preferably, the film layers are the contacting longitudinal edges of a single thermoplastic film web bent into tubular shape around articles resting on a conveyer belt 12. The V-belts 6, 7 are trained about driven pulleys 2, 3 and idle pulleys 4, 5, 8, 9, the pulleys each having two grooves. The pulleys 3, 5 are mounted on supports 3a, 5a secured to horizontal guides 16 and the pulleys 2, 4 are mounted on supports 2a, 4a slidable on the guides 16. To facilitate the initial threading of the film 11 through the machine, the belts 6 are moved away from the belts 7 by operation of levers 2b, 4b to move the supports 2a, 4a against the action of springs 2d, 4d. The pulleys 8, 9, which tension the belts 6, 7, are connected by lugs 8a, 9a to the supports 4a, 5a so that the pulley 8 is slidable with the support 4a. Two nozzles 17, 18 blow hot air into the gap between the belts 6, 7 and are connected to chambers 17a, 18a having heating resistors 17b, 18b therein. Air is supplied through pipes 17c, 18c. The nozzles 17, 18 are connected through a linkage to a rod 20 rigid with the core of a solenoid 21 and toggle-jointed at 26 to blocks 27 having grooves 27a in which supports 28 are slidable. The supports 28 are movable to adjust the distance of the nozzles 17, 18 from the film edges to be welded. When the machine stops, the solenoid 21 is actuated to raise the rod 20 and, through the linkage shown in Fig. 2, the nozzles 17, 18 are moved away from the film edges. Simultaneously, an electro-valve (not shown) cuts off the air supply and cuts off the resistors from the normal voltage source and connects them to a reduced voltage source to prevent burn-out of the resistors and damage to the film 11. |
