Patent GB-1474921-A (GB)
Title: Method for post forming heat-formable laminates
IPC: B29C43/52
Filed: 1974-08-08
Abstract: 1474921 Folding and finishing edges of non-metallic sheet material STEELCASE Inc 8 Aug 1974 [8 Aug 1973] 35011/74 Heading B5K An overhanging portion 3 of a laminate 2 is folded and secured around an edge 5 of a substrate 1 by heating the portion 3 by concentrating a line of heat along the surface of the portion 3, on the line on which the portion 3 is to be bent, and additionally maintaining a temperature in the area surrounding the portion 3 which is sufficiently high to soften the portion 3; and discontinuing the heating and immediately forming the portion 3 over the edge 5. Preferably, the substrate 1 is a metal or wooden table top and the laminate 2 is a decorative laminate employing a melamine overlap on a thermolinking phenolic layer. The laminate 2 is attached by an adhesive to the substrate 1 preferably with a thermal insulation strip 4, Fig. 3, of kraft paper or masking tape therebetween. A support 30 for the substrate, Fig. 1, comprises a bed 33 on a frame 31 pivotable about brackets 38 on a frame 10 by a piston-andcylinder actuator 39. The bed 33 includes pairs of bars 36, Figs. 2 and 3, along which the substrate 1 is slidable over dogs 37 each pivotally mounted between a pair of the bars 36 to depress the dogs until they pop up again in front of an edge 6 of the substrate 1. The operator pulls the substrate back towards him until the edge 6 engages against protruding edges 37a of the dogs 37. A clamp 40, Fig. 1, to clamp the substrate 1 and its sheet 2 to the table 30 comprises an inverted T-section bar 41 movable by actuators 42 one on each side of the support 40 and movable with the pivoting of the support 30. A heater 50, Fig. 1, is mounted on a support 60 pivotable by an actuator 62 about brackets 61. A bolt 64 limits the forward movement of the heater 50. The heater 50, Fig. 6, comprises a metal shroud 51 wrapped around a plurality of C-shaped bulkheads 53 the inner edges of which support a part-octagonal metal reflector 54 having brackets 55, 56 thereon which support electrical heating elements 57, 58 and 59, respectively. A heat shield 59a is mounted on the brackets 56 and a copper screen heat shield 200 is mounted between the elements 57, 58. Any one or any combination of the elements 57, 58, 59 is energizable according to the material of the sheet 2. A former 70, Fig. 1, is supported by a C- frame 20 comprising a plurality of interconnected C-shaped plates 21 and comprises aluminium plates 71, 72, Fig. 11, and an intermediate plate 73. The plates 72, 73 are joined together and are movable as a unit relative to the plate 71 by a slide bolt 76 screwed into the plate 73 and slidable in an elongate slot 81a in the plate 71 secured to angle irons 80 connecting the former 70 to the frame 20. The plates 71, 72 project forwardly and rearwardly beyond the plate 73 which carries a cushioning strip 74. A cooling fluid is circulated through tubes 75 in the plates 71, 72. The plates 72, 73 are drivable forwards and rearwards along the angles 80 by toggles 83 each connected to an angle 80, the toggles 83 being kinked or straightened by a bar 86 joined to the mid-point of each toggle and which is connected, through a shock absorber (300), Fig. 19 (not shown), to a piston- and-cylinder actuator (87), Fig. 12 (not shown). In operation, with the substrate 1 and the sheet 2 clamped by the bar 41 on the support 30, the heater 50 is moved forwards until the support 60 hits the bolt 64 and the edge 3 is heated. After a predetermined time, the heater 50 is retracted and the table 30 is pivoted to position of Fig. 8 so that the heated edge 3 is wiped past the rounded lower edge of the plate 72 and is folded downwardly over the edge 5 of the substrate 1. When the substrate 1 is aligned with the opening between the plates 71, 72, the plates 72, 73 are driven forwardly and rounded edges 71a, 72b of the plates 71, 72 effect bending of the portion 3 around the edge of the substrate 1. After a predetermined time, the former 70 is retracted and the support 30 is pivoted back to its horizontal position. The bar 41 is lifted and the finished table top is removed. An electrical control circuit for the operation of the apparatus is described, Fig. 14 (not shown). In modifications, (a) the former (270), Figs. 16 and 17 (both not shown), is pivotally mounted at (271) and (b) only the plate (73), Fig. 18 (not shown), is drivable by the toggle (83), the plate (72) being separately drivable by a piston-and-cylinder actuator (380).