| 摘要 |
1502773 Sealing bags THAMES SACK & BAG CO Ltd [trading as THAMES PACKAGING EQUIPMENT CO] 12 Feb 1975 [14 Feb 1974] 6832/74 Heading B8C [Also in Division B5] Hot air heat sealing apparatus for sealing together two thermoplastic layers, e.g. the mouth of a filled plastics bag or sack, comprises ducting 50, 52 arranged to divide the air stream from a fan 36 into at least two flows, a heater 41 arranged in the path of one of the flows, means by which air heated by the heater is directed, in use, on to the layers to soften these layers at the region to be sealed, means 20, 21 for pressing the layers together to form a seal, and means disposed in the path of the other of the flows to direct this flow into contact with the layers above the region to be sealed to cool the area above the region and preventing softening of the layers in this region. As shown in Figs, 2 and 3, the fan 36 is connected to four ducts 50, 51, 52, 53, the duets 50, 51 containing cartridge heaters 41, 42, respectively. The filled bags or sacks pass through a central passage 55 in the apparatus and are guided thereinto by a guide 45. Top guides 43, 44 define an upper channel 55<SP>1</SP> and are fixed at one end to the ducts 52, 53, respectively, by curved tab portions 43a, 44a, the lower edges being curved inwardly at 43b, 44b. The lower ends of the ducts 52, 53 are closed and slits are formed in these ducts adjacent the internal faces of the guides 43, 44 so that the air from the ducts 52, 53 keeps the upper portion of the bag in the channel 55<SP>1</SP> cool whilst the portion immediately therebelow is heated by air from the ducts 50, 51. The softened regions of the bag are sealed by crimp rollers 20, 21, Fig. 4, one of which is knurled. The roller 20 is mounted for pivotal movement about a pintle 10 on a ball bushing 15 so that it can be moved radially towards and away from the roller 21. A plunger 54, Fig. 6, is rotatable by a key (not shown) to move inwardly or outwardly of a housing block 52 to act on a bearing block 12 for the bushing 15 so as to pivot the roller 20 about the bushing 15. A set screw 103 passing through an extension of the block 52 bears against the undersurface of a cantilever arm 102 fixed to the block 12. Rotation of the screw moves the arm 102 to alter the inclination of the axis of the roller 20 whereby the axes of the rollers 20, 21 may be brought into parallelism. |
