METHOD AND APPARATUS FOR APPLYING POLYMER COATING ONTO METAL PIPE

摘要

FIELD: production of metallic tubes whose inner and outer surfaces have polymeric coatings. SUBSTANCE: method comprises steps of forming tubular casings by extrusion of adhesive and polymer and applying them on inner and outer surfaces of tube. Said adhesive and polymer are formed directly on tube; zones of forming outer casings are arranged in opposite relative to zones of forming inner casings. Apparatus for performing the method includes outer extrusion head axial opening in which inner extrusion head is placed with annular gap. Both extrusion heads include two chambers for forming adhesive and polymer on surface of metallic tube drawn through said annular gap. Said chambers are opened to annular gap at one side, and arranged successively and combined in pairs by their cross sections. Inner extrusion head is in the form of monolithic part with inner ducts for separate feed of adhesive and polymer to both chambers. Chambers of extrusion heads are in the form of profiled borings and turnings having forming portions joined with sizing ones. Forming portions have helical recesses of mutually opposite directions on their surfaces. EFFECT: higher efficiency.