Patent GB-1052312-A (GB)
IPC: B65B51/30
Abstract: 1,052,312. Seaming non-metallic sheet material. FMC CORPORATION. April 20, 1964 [May 14, 1963], No. 16368/64. Heading B5K. [Also in Division B8] Superimposed continuous thermoplastic sheets are seamed by moving the sheets along a predetermined longitudinal path, slidably receiving a longitudinal marginal region of the sheets in a passage, interconnecting such marginal regions by a seaming means 82 to form a fused seam, and moving the seaming means 82 out of intersecting relation with the marginal regions when these regions cease movement through the passage. In a wrapping machine 12, articles 16 to be wrapped are supplied by a conveyer 14 toward a former 18. A thermoplastic web from a roll (not shown) is threaded through the former 18 which causes the web to be folded about the longitudinal median thereof. The articles 16 pass through a passageway 24 formed between members 20, 22 of the former 18 to be successively introduced between the superimposed, sheets S. The free marginal portions of the sheets S are positioned between blocks 84, 86, Fig. 2, of a cutting and sealing apparatus 10 and, in operation, a cutting and sealing element 82 is positioned as shown in Fig. 2 so that passage of the sheets S causes the marginal portions to be cut and seamed with the formation of a waste strip W. A bar 106, Fig. 6 (not shown), having a twisted end is provided to urge the strip W away from the sheets S immediately following the seaming. The sheets S then pass between belts 118,120 which convey the sheets and the articles 16 therein to a transverse cutting and sealing mechanism 26 which forms separate packages by cutting and sealing between the articles 16. The strip W is also frictionally engaged by the belts 118, 120 and is directed over the belt 118 to the end-122 of a vacuum conduit 124. Alternatively, the conduit 124 may be positioned to remove the strip W immediately after cutting. The blocks 84; 86 are mounted on a limb 70 of a bracket 32 and have a spring 100 located in counterbores 98 therein and'which is compressed so as to tend to separate the blocks 84, 86 to facilitate the location of the sheets S in the slot 96. Opening 102 for the element 82 are provided and openings 104, Fig. 7, are situated on the downstream side of the openings 102 to prevent the fused joint contacting anything whilst still soft and tacky. Cooling gas or liquid may be circulated through cavities 108 formed in the blocks 84, 86. The element 82 comprises a U-shaped resistance element and is secured to electrically-conductive bars 78 on a block 74 of dielectric material. The block 74 is secured to a rod 72 mounted on a rod 46 which is connected to an armature 64 of a solenoid 62 by a spring 66. The rod 46 is vertically reciprocable but not rotatable in a bore 44 in a block 38 mounted on a limb 40 of the bracket 32. A bolt 56 on a plate 50 mounted on the top of the rod 46 abuts the block 38 to limit the downward movement of the rod 40 which is urged upwardly by a spring 60. The springs 60, 66 are chosen so that a greater force is required to stretch the spring 66 over a given distance than the force required to compress the spring 60 over the same distance. Upon energization of the solenoid 62 the rod 46 moves downwardly so that the element 82 is in the operative position in the openings 102, as shown in Fig. 2. The height of the apparatus 10 may be adjusted by adjusting the position of the bracket 32 relative to a fixed frame 30.