Patent GB-1449767-A (GB)
Title: Method and de-ice for applying a sheet of plastics material to a solid body
IPC: B29C65/00
Filed: 1974-05-20
Abstract: 1449767 Glass laminates; laminating apparatus SAINT-GOBAIN INDUSTRIES 20 May 1974 [25 May 1973] 22497/74 Heading B5N A method of applying a sheet 38 of plastics material to a smooth surface of a solid body 35, e.g. a glass sheet, comprises the steps of arranging the sheet between the body and an inflatable membrane 20 in a vacuum enclosure, the periphery of the membrane being fixed at a location separated from the surface of the body, controlling the pressure on each side of the membrane to inflate the membrane on the side remote from the body to press the sheet against the body and causing the portion of the membrane pressing the sheet against the. body to progressively expand from the centre portion thereof to the periphery. A device for effecting the method comprises a container formed of two separable members 1, 2 which can be hermetically sealed together, the container having holding means, e.g. pins 34 constituting the piston rods of rams 36 therewithin for supporting the body with said surface in a generally horizontal. position, an inflatable membrane 20 of elastic resilient material, e.g. a. silicone rubber below the holding means and extending across the whole area of the container, the periphery of the membrane being rigidly held at a location separated from the holding means, controllable means for removing air from the container and controllable means for producing an excess pressure between the bottom of the container and the membrane to cause the membrane to inflate and press the sheet against the body, the arrangement being such that the portion of the membrane pressing the sheet against the body progressively expands from the centre portion thereof towards the periphery. In the embodiment of Fig. 1, the upper half 1 of the container is movable towards and away from the lower half 2, the bottom 12 of the lower half having a recess 13 connected to duct 15 by conical portion 14, the duct being connected by valves 16, 17, 18 to pressurized, atmospheric or vacuum ducts. A metal mesh cloth 19 is interposed between the membrane 20 and the bottom 12. The upper half 1 of the container has a recess 23 connected to duet 25 by conical portion 24, duct 25 being connected to duct 15, a fine metal mesh cloth 26 and. a membrane 27 being provided on the upper half 2 of the container. In use, the sheet 38 of plastics material, optionally coated with a heat-activatable adhesive is placed over the membrane 20, the glass sheet 35, optionally preheated, is placed in position and the container closed. The valve 18 is opened to apply a vacuum to the rear faces of the membranes 20, 27 and the valve 39 then opened to connect duct 30 to a vacuum pump to evacuate the interior of the container, the valve 18 then being closed and the valve 17 opened slightly to slowly establish atmospheric pressure behind membranes 20 and 27 and thus slowly inflate the membranes. During this operation, upper membrane 27 and sheet 28 carried by the lower membrane 20 come into contact with the central portion of the glass sheet 35 at almost the same time, valve 39 remaining open so that air continues to be drawn out while sheet 38 is applied to the glass sheet so that lower membrane 20 comes into contact with the glass sheet 35 slightly in advance of membrane 27 and relieves pins 34 which are withdrawn by their rams at the instant at which glass sheet 35 becomes supported by the lower membrane. When atmospheric pressure is re-established, valve 17 is closed and pressurized air introduced through valve 16 until a pressure of about 2 atmospheres is exerted on the components, the valve 17 is opened and the laminated product removed from the container. In an alternative device shown in Fig. 5, the container has a lower portion 40 and a pivotable upper portion forming a cover 42, the cover comprising a rigid concave mould 47 corresponding in shape to the glass sheet 50 which is fixed to the mould by a pneumatically operated gripping device. A convex counter-mould 55 is disposed in the lower part of the container, the counter-mould having at its centre a conical opening 56 connected to a duct 57, duct 57 being subjected to pressurization, atmospheric pressure or vacuum by valves 58, 59, 60 respectively. A fine metal mesh cloth 61 is placed upon the surface of counter-mould 55 and is overlaid by a membrane 62 of silicone rubber supported at its periphery.