GB1500961A - Process and apparatus for the production of individual rimmed plastics containers - Google Patents

Abstract

1500961 Thermoforming and filling containers PORTION PACKAGING Ltd 13 March 1975 10589/75 Heading B5A Containers with rims are thermoformed from flat plastics blanks 26 which are essentially rigid at ambient temperature by fixing the periphery of the blank, heating the unsupported central portion to a formable temperature while leaving the periphery at a temperature at which it remains rigid, and forming the central portion into the container, the periphery becoming a rigid rim of greater thickness than the thermoformed portion. Polystyrene, polyethylene, or P.V.C. blanks are heated to a temperature sufficient to sterilize them, at least 280‹F., formed into containers by vacuum, air pressure, or a heated plug, filled with foodstuff and closures applied in one machine. In a turntable machine, Fig. 2, blanks 26 retained in a stack 27, Fig. 6, by an 0-ring 31 are drawn off by a suction device 35 and released to lie across an aperture 32 in the turntable 10 by engagement with a ring 33 having two arcuate shoulders 34 to locate the blank. The blank is indexed through five stations of a heating device 20 where electrically heated pads 43 are pneumatically pressed against both faces. At the forming station 21 a heated forming plug 52, Fig. 10, is mounted on the piston-rod 49 of a cylinder 48 and carries a relatively slidable and downwardly spring biased ring 53 for clamping the periphery of the blank during descent of the plunger 52. Simultaneously a member 58 containing the mould cavity 62 is raised into the aperture 32 and vacuum is applied to fully form the container. The container is filled at 22 through a pipe 67 by a pump 64 and a closure is applied at 23 from a reel of interconnected closures 69. At a first station the closure is severed and at a second station the closure is fully heat sealed by a heated pad 70. A guide track 24 lifts the containers and discharges them into a receptacle 73. In Fig. 5 a conveyer 76 comprises plates 78 forming four rows of apertures 32 to which are attached rings 33 for forming containers and filling at stations equipped as in the first embodiment. The containers are fitted from an array of nozzles 80<SP>1</SP> in two stages and a knife 81 severs the strings of closures 69. Alternatively, Fig. 13, the conveyer comprises plates 78<SP>1</SP> having apertures 106 with annular grooves 111 into which blanks 26 are snapped by reciprocating suction cups 112. As the conveyer is indexed forward heated pads 122, 124 are applied to both sides of the blank, and then a heated plug 136 descends to stretch the blank while a mould 138 ascends to vacuum form the container. Rings 134 on a spring biased member 132 and an annular shoulder 140 engage opposite sides of the blank adjacent the peripheral portion in the groove 111. The blank in this position has received heat from the pads 122, 124 and is drawn down a little to ensure integrity at the rim junction. As the moulds 138 are raised, annular members 156 are raised to engage the previously formed containers and snap the rims out of the grooves 111. The blanks may be an interconnected series, Fig. 17, which are pressed into grooves 111 in apertures 106 by a wheel 168 which passes through slots 166 between the apertures.