Patent GB-1433000-A (GB)
Title: Method of and apparatus for continuously bonding metal foil to sheet metal
IPC: B29C63/00
Filed: 1973-05-25
Abstract: 1433000 Laminating method and apparatus HEATSHIELD RESEARCH & DEVELOPMENT PTY Ltd 25 May 1973 [1 June 1972] 25189/73 Heading B5N A method of continuously bonding metal foil to sheet metal by an interposed film adhering to both and separating the two from direct contact, includes the steps of continuously drawing the sheet metal from a roll, continuously superimposing the film on the moving metal sheet, continuously superimposing the foil on the film and sheet metal, drawing the resultant assembly in tension along the convex surface of a fixed flexible curved pad 62, the foil against the pad, and applying heat to the sheet metal as the assembly is being drawn along the curved pad to heat the film by conduction, the heat conducted to the film within the curved tensioned assembly causing bonding of the film to the foil and the metal sheet. An apparatus for effecting the method comprises a fixed flexible substantially rectangular pressure pad having a longitudinally curved convex surface, means for continuously superimposing polyethylene film on to the metal sheet being drawn from a roll, means for continuously superimposing metal foil on to the polyethylene superimposed on the sheet metal, means for drawing the resultant assembly in tension along the curved convex surface of the pressure pad, the foil against the pad, and means for heating the sheet metal as the assembly is being drawn along the curved surface of the pressure pad to heat the film by conduction, the heat conducted to the film and the pressure on the film within the curved tensioned assembly causing bonding of the film to the foil and the sheet metal. In the embodiment described, galvanized sheet steel 10 is fed under tension from a motor driven roll, passed under a cleaning brush 16 and between two pairs of tension rollers 20 and 21, a pivoted roller 22 being mounted between the two pairs of tension rollers, the sheet steel is then passed over three parallel idler rollers 30, 31, 32 and conveyed unsupported past the pressure to the idler roller 34 and to a driven recoiling roller 38 which maintains it in tension whilst the machine is in operation. Polyethylene film 39 is drawn from its roll and, guided by rollers 41 is carried forward and brought down behind and under parallel transverse cylindrical bars 42 and 43 and, as the steel sheet is drawn dose under the lower bar 43, the film is at a near this point brought down on to the steel and is carried forward with it over support roller 44 and over rollers 30, 31, 32 which are arranged to impart curvature to the steel drawn over them, four oblique resilient rollers (Fig. 5, not shown) mounted to bear with adjustable pressure on the film where it is drawn past the bar 42 to prevent longitudinal tension of the film, a further pair of oblique rollers (Fig. 6, not shown) being mounted to bear with adjustable pressure on the film where it is superimposed on the steel sheet 10, above support roller 44 to urge the side parts of the film outwards, to give lateral tension to the film and to increase friction on the film passing the bar 42. Aluminium foil 40 drawn from a roll is passed over transverse roller 47 and under transverse roller 48 before contact with the film overlying the sheet and being drawn over rollers 30, 31, 32, tension in the foil being equalized by carrying it under a resilient transverse brush 49, lubricating fluid, e.g. dimethyl siloxane being applied from reservoir 51 to the upper surface of the foil prior to superimposing the foil on the film, the film and the foil being of about the same width and narrower than the steel, the film being applied to the steel in laterally offset manner so that a strip at one side of the steel is uncovered by the film and so that the film slightly overlaps the other side of the steel, the foil being offset slightly more in the same direction, lubricant being applied to the uncovered strip from reservoir 60. A large part of the steel, film and foil assembly which is suspended between the rollers 32 and 34 is covered by a weighted pressure pad assembly 62 which includes a rectangular sheet 63 of flexible glass fibre cloth, its rear end fixed to a transverse member 57 and overlaid with a resilient pad 64 of heat insulating material, covered by a rectangular section 65 of flexible sheet material both connected at their rear ends to member 57. Over the section 65 is a flexible mesh panel 66 carrying a number of weights 67 in longitudinally and laterally aligned arrangement. The heating means comprises a plurality of gas jet orifices in transverse gas manifolds 71 mounted on pairs of vertically adjustable standards 70. An angle section 72 is secured across the front end of the pad assembly 62 and is connected by a pair of straps 73 to cables 74 which pass around a pair of pulley wheels 75 and are operatively connected to an assembly of compression springs 76 which, during the operation of the machine are compressed by the extended piston of an hydraulic cylinder 77, control means being provided so that an interruption of the passage of the steel sheet, the supply of gas is discontinued, cool air is directed through the gas sheets and the piston of cylinder 77 is retracted to lift the pressure pad assembly 62. Means are provided to trim the edges of the laminate prior to further heating it by gas jet manifold 84 and coiling the product.