GB1083022A - Heat sealing lids onto preformed containers - Google Patents

Abstract

1,083,022. Packaging-machines. PACKAGING INDUSTRIES Ltd. Inc. Aug. 26, 1964 [Sept. 12, 1963], No. 34965/64. Heading B8C. [Also in Division B5] Apparatus for securing a plastics or cardboard closure to the flanged mouth of a plastics container includes a support apertured to receive the container body and heating means comprising an electrical resistance strip conforming in shape to the flange and either surrounding the aperture or mounted in a pressure plate above the support, the heating means being conneotible to sources of current at different voltages to cope with the demands of the various shapes of heating element. The device may secure covers over filled blisters in a web. The supports may be readily changed to accommodate different-sized packages and packages requiring different sealing temperatures. In one embodiment, rails 12, 14<SP>1</SP> carry container supports 18, 20 and pressure plates 100, 150 mounted individually on rollers, the arrangement being that a support and superposed pressure plate are beneath a vertically movable plunger 42 while the other support is being loaded. As shown, the support 20 is loaded with filled containers and covers are placed upon them, the latter being located by retractable pins (not shown). The support is then advanced to the left and picks up the pressure plate 100. Both move beneath the plunger 42, the assembly 150, 18 having been drawn out to the left. In so moving, the plate 150 is halted clear of the pressure applying station and the support 18 passes-from beneath it to expose the scaled packages for removal. A polytetraflourethylene strip 110, Figs. 9, 9A (not shown), may join each support and plate and extend between them during sealing. In another embodiment, Figs. 1-3 (not shown), the plunger carries a single pressure applying plate and supports are slid beneath it on rails. The supports may each have differentshaped apertures each surrounded by a heating element. In both embodiments spring-loaded retractible stripper pins thrust the package clear of the pressure plate when the pressure is removed. The heating elements are thin uniform width strips such as the rectangular frame in Fig. 4 (not shown), of stainless steel or other relatively high-resistance conducting material. Current is supplied at two equidistant points, L1, L2 on opposite sides of the frame. The strips may be non-continuous (Fig. 4c, not shown). They may be backed and covered by glass cloth or the like, the covering being polytetraflourethylene coated or impregnated. The circuits may be formed through the supports and pressure plates and the stripper pins may act as connectors between them. The differing voltage demands for various lengths of strips as a support for different-sized containers are catered for through sets of terminals for the respective voltages.