| 摘要 |
1,012,216. Laminates and laminating. KOPPERS CO. Inc. Feb. 18, 1963 [March 12, 1962]. No. 6525/63. Heading B5N. A method and apparatus for heating a web is characterized by moving the web past a source of heat and selectively interposing a film of gas under pressure between the web and the heat source. As shown, applied to apparatus for applying paper webs on each side of a web of corrugated cardboard, the composite web 13 is drawn between a pressure belt 14 having subsidiary pressure rollers 18, and a series of steam-heated platens 12, traction being effected at the delivery end of the apparatus by the belt 14, which passes around a roller 17, and a co-operating belt 19 driven from an electric motor 48. Steam is delivered to the platens 12 through branch pipes 22 from a manifold 21, and compressed air is delivered from a manifold to pipes 34, 36, 37, each of which has branches 31, 32, 33 connected to four individual platens in three groups. The pipes 34, 36, 37 each include a solenoid valve 38, 39, 41 and these can be opened in succession via a temperature sensitive element 43 which is placed at the delivery end of the heating platens 12 and is connected to the valves through an amplifier 47 and voltage-operated control elements 44, 45, 46. The four air-delivery pipes in the groups 31, 32, 33 may each terminate in a nozzle opening into a lip in the approach edge of the corresponding platen 12 or may open elsewhere in the top face of the platen. In operation, should the web 13 be slowed or stopped, overheating is prevented by the action of the element 43 which opens the valves 41, 39, 38 in succession as the temperature rises thus admitting compressed air successively beneath the web through the pipes 31, 32, 33. When starting up the apparatus air is supplied through pipes which by-pass the valves 41, 39, 38 by opening a valve 51, the air serving the double function of cooling the web and providing a cushion facilitating its threading through the apparatus. In a modification the valves 41, 39, 38 are connected across the electric supply to the driving motor 48 and are operated, to supply air beneath the web, by the change in armature voltage when the motor slows or is stopped. |
