The coated board used in the can-making industry, commonly known as coated steel, is made of PET, PC, PE or PP film and metal plates (galvanized plate, cold-rolled plate, aluminum plate and stainless steel plate). The inner side of traditional metal cans must be painted, and the substance bisphenol A contained in the painting method will have harmful effects on human body and environment, especially edible cans. The birth of metal plate film covering technology is the progress of metal can production. With its wide application, the traditional metal can production process and technology will be subverted, and productivity, production cost, cleanliness and sanitation, environmental protection and other aspects will also make a big step forward.。The production line of coated iron is mainly composed of Kyle iron uncoiling part, welding and iron performance quality inspection, substrate heating, coating unit, cooling unit, product inspection and oiling coiling, among which the core part is the heating area of substrate and coating unit. The temperature above the melting point of the steel strip film is heated by the preheating part of the electromagnetic induction heating roller, and the hot-melt bonding of the substrate and the film is carried out by the extrusion of two symmetrical pressure rubber rollers. The hot-bonded steel strip is rapidly cooled by a cooling device to ensure the rapid recrystallization of the melted polymer.