Patent GB-1083284-A (GB)
Title: Improvements in or relating to heat sealing heat sealable material
Inventor: SMYTH STANLEY PETER
IPC: B26F3/06
Filed: 1964-11-24
Abstract: 1,083,284. Seaming non-metallic sheet material. ECONOMY POLYTHENE PRODUCTS Ltd. Feb. 23, 1966 [Nov. 24, 1964; July 12, 1965], Nos. 47810/64 and 29499/65. Heading B5K. Two webs 19, 20 of heatsealable material arranged in face-to-face relation are heatsealed by placing the parts 21, 22 of the webs to be sealed in alignment with grooves 12, 18 in relatively movable members 11, 17, respectively, positioned so that the open faces of the grooves 12, 18 are aligned and facing each other, Fig. 2, the member 11 carrying a heat-sealing member 16 extending in the longitudinal direction of the groove 12 and at least partly outside this groove along at least part of its length; moving the members 11, 17 relatively to one another to sandwich the webs 19, 20 therebetween with the parts 21, 22 lying across the open faces of the grooves 12, 18 and displaced by the member 16 out of the plane of intersection of these open faces into the groove 18, Fig. 3 (not shown); applying heat to the displaced parts 21, 22 through the member 16 to seal the webs together, Fig. 4 (not shown); and moving the members 11, 17 relatively away from each other to release the heat-sealed webs 19, 20. Preferably, the heat applied is so intense that the webs are simultaneously severed to form beads 24, 25, Fig. 4 (not shown). The member 16, preferably a nickel-chrome alloy resistance wire, is mounted between arms 13, 14, Fig. 1 (not shown), on the member 11. A collar 62, Figs. 1 and 5 (both not shown), abuts against the arm 13 and the wire 16 is attached to a screw 65 within a sleeve 63. As the wire 16 heats up and expands, a compression spring 67 forces the sleeve 63 outwardly from the member 11 to maintain the wire 16 taut. Alternatively, the wire 16 is secured between a block 48, Fig. 6 (not shown), and a nut 50 and, on expansion of the wire, a compression spring 41 acts to force a sleeve 38 out of a slideway in the member 11. The member 11 may be attached to the ram of an hydraulic press to be raised and lowered thereby. The member 17 comprises a stationary part 26 and a movable part 27 formed with the groove 18. Studs 32 have reduced ends 34 screwed into the part 27 and larger diameter shanks forming slideways for apertures 35 in a limb 30 of the part 26. Compression springs 29 normally urge the part 27 away from the part 26. In use, the member 11 clamps the webs 19, 20 against the part 27 which continues to move downwardly until it contacts the top face of the limb 30. The switching on and off of the current may be controlled by a member 52, Figs. 8 and 9 (both not shown), secured to the member 11 and which carries a piston 55 which acts against a spring 56 in a cylinder 57. A plunger 58 on the piston 55 actuates a microswitch 60 to supply current to the wire 16 when the member 11 has pushed the part 27 into contact with the limb 30. Upon reversal of the member 11, the switch 60 is opened before the member 11 and the part 27 have separated. The grooves 12, 18 may be lined or coated with heat-insulating and heat-resisting material as well as electrical-insulating material, e.g. polytetrafluoroethylene, or may be formed of such a material, e.g. hard rubber. Parallel to the longitudinal boundaries of the grooves 12, 18, the members 11, 17 may be formed with co-operating grooves and ribs. The grooves 12, 18 may be square, rectangular or semi-circular in section. The wire 16 may be of circular section or may be a flat strip mounted so that its narrow dimension is transverse to the width of the groove 12.