| 摘要 |
<p>1479416 Seaming non-metallic sheet material SIG SCHWEIZERISCHE INDUSTRIE-GES 11 Dec 1975 [27 Jan 1975] 50779/75 Heading B5K Apparatus for transversely welding and severing superimposed layers 25 of thermoplastic sheet material, e.g. superimposed webs or a flattened tube of plastics film, comprises two counter-rotatable welding jaws 3, 4 which simultaneously act upon the layers 25 from each during each revolution, the jaw 3 having a wedge-shaped head 7 with a tip 10 providing a cutting edge and the jaw 4 having a stripshaped anvil surface 21 co-operable with the cutting edge, the surface 21 being flanked by two resilient heat-resistant elongate members 20 1 , 20 2 , the jaw 4 being displaceable towards its axis of roation against resilient biasing means 14 and the distance between the axes of the jaws being less than the total of the maximum radial distances of the cutting edge and the surface 21 from the respective axes of rotation, whereby the jaw 4 yields when the jaws 3, 4 strike against one another. As shown, the steel jaw 3 has a foot 5 let into a groove 6 in a rotatable shaft 1, has an electrical heating element 8 embedded therein and is provided with cover plates 9 to prevent the layers 25 becoming overheated and to act as hold-down devices for the layers 25. The jaw 4, preferably unheated, is carried by bolts 12 displaceable in diametrical bores 13 in a rotatable shaft 2 and is urged away from the shaft 2 by compression springs 14 so that heads 17 on the bolts 12 normally engage shoulders 18, Fig. 3a. Heat-resistant artificial rubber elongate members 20 1 , 20 2 project from grooves 19 one on each side of the anvil strip 21. As the shafts 1, 2 rotate, the surface 21 and the tip 10 describe cylindrical surfaces 22, 23, respectively, the radii of which may be equal. Alternatively, the radius of the surface 22 may be 0À96-0À99 that of the surface 23. In operation, the layers 25 are fed, e.g. by rollers, at a speed corresponding to the peripheral velocity of the tip 10 and, as the jaws 3, 4 approach each other from the Fig. 3a position, the layers 25 are clamped between the member 20, and a flank 28, of the head 7 to form a first welded seam (29), Fig. 4 (not shown). As the jaws 3, 4 strike against each other, the jaw 4 is moved against the action of the springs 14 so that in the Fig. 2 position a clean cut (30) is made through the layers 25. Then, the flank 28 2 of the head 7 and the member 20 2 clamp the layers to form to second weld (31). In modifications (not shown), instead of the jaw 4, the jaw 3 is radially displaceable against spring pressure or both jaws 3, 4 are radially displaceable. Instead of springs, pistons acted on by compressed air may be provided.</p> |
