GB1195764A - A Machine for making Welded Thermoplastic Bags - Google Patents

Abstract

1,195,764. Seaming non-metallic sheet material. I. D. BELLA. 5 June, 1968 [11 Nov., 1967], No. 26785/68. Heading B5K. A machine for welding bags from intermittently-supplied thermoplastic film 10 comprises welding means 5 to simultaneously cut and weld the film 10, a film feeding mechanism 4 immediately preceding the welding means 5 and comprising a pair of rollers 11, 12 with reverse lock, and a bag extractor and ejector 6 arranged immediately behind the welding means 5 and having a drive controlled by the drive of the mechanism 4. As shown, the film 10, either in the form of a flattened tube cut lengthwise or a longitudinally folded web, passes from a reel 3 over a tensioner 7 and around earthed metal rollers 8a, 8b, 8c to the feed rollers 11, 12 made of or coated with rubber and having peripheral grooves 13 into which wiping elements 14 extend to guide the film to the welder 5. The rollers 11, 12 are interconnected by spur gears 26a, 26b mounted on their respective spindles 24, 25, the spindle 24 being driven by a motor 15 through a chain 16, a shaft 17, a crank 18, 19, a rod 20, a freewheeling rocking lever 21, a partially-rotated shaft 22 and a chain 23. Reverse rotation of the spindle 25 is prevented by a freewheel drive 27 mounted thereon. The welder 5 comprises lower clamping jaws 28 having a non-slip coating thereon and vertically movable upper clamping jaws 29 mounted on arms 30 located one at each side of the film 10 and urged downwardly by springs 31. A cutting and welding wire 32 extends between the arms 30 retained at their upper ends on a guide 33 mounted on rods 34 one on each side of the machine. The rods 34 move vertically in a frame 35, are urged downwardly by springs 36 and each carries a roller 37 riding on a cam 38 on a common shaft 39 driven by a chain 40 from the shaft 17. The extractor and ejector 6 comprises two sets of narrow belts 41, 44 passing around grooved rollers 42, 45 and tensioning rollers 43, 46 and is driven by a chain 49 from a motor 47 controlled by a switch (50), Fig. 3 (not shown), on the shaft 17. The speed of the belts 41, 44 is always greater than the peripheral speed of the rollers 11, 12. Preferably, at least the outer belts 41, 44 on the open side of the bag are offset relative to the open edge of the bag. In operation, the heating current for the wire 32 is switched on and the motor 15 is started to cause a revolution of the shaft 17 which actuates the switch 50 and rotates the rollers 11, 12 to withdraw a length of film 10 from the reel 3 corresponding to the setting of the crank drive 18, 19, this feed taking place only during the second part of the rotation of the shaft 17 after the termination of an operation by the welder 5. Rotation of the cams 38 allows the springs 36 to be freed to lower the welding equipment so that the jaws 29 press the film 10 against the jaws 28 and, after further downward movement, the wire 32 severs and welds the film. Upon further rotation, the wire 32 and the jaws 29 are raised. An electrical circuit for the operation is described, Fig. 4 (not shown).