MANUFACTURING METHOD AND EQUIPMENT FOR THREE-LAYER POWDER-POLYETHYLENE COATED STEEL PIPE

摘要

A manufacturing method and a manufacturing device for a powder fusion polyethylene trilaminar coated steel pipe are provided to improve the quality of the steel pipe by preventing the exterior of the steel pipe from being cooled by spraying the polyethylene powder with the air of the high temperature. A manufacturing method for a powder fusion polyethylene trilaminar coated steel pipe is as follows. The foreign material adhered to a pipe is removed by the blasting treatment. Abrasive or dusts sticking on the inside of the pipe duct are removed. A steel sheet is heated at 260~280‹C so that the epoxy powder and polyethylene powder is fused. A first powder injector spays the power to a heated steel pipe exterior in order to make an epoxy coated layer(L1). A second powder injector spays the modified polyethylene powder on the epoxy coated layer in order to make an adhesive polyester coated layer(L2). The steel pipe is positioned at a turning table to rotate the steel pipe. A third powder injector spays the polyethylene powder to the exterior of the steel pipe rotating in order to make a final polyethylene coated layer(L3).