초록 ▼

The present invention relates to a method and apparatus for obtaining a metal-plastics composite tube. A layer of grafted polyethylene which comes directly into contact with the metal and a layer of cross-linkable polyethylene are extruded simultaneously at least inside this tube, with the aid of an

The present invention relates to a method and apparatus for obtaining a metal-plastics composite tube. A layer of grafted polyethylene which comes directly into contact with the metal and a layer of cross-linkable polyethylene are extruded simultaneously at least inside this tube, with the aid of an extrusion nozzle having an annular conduit with two distinct coaxial inlets and a single outlet. The invention results in a composite tube having the malleability of lead, the rigidity of copper and a total inertia with respect to the aggressive agents flowing therein.

대표청구항 ▼

A method for the manufacture of a metal tube having two layers of plastics materials coated on the internal surface thereof, comprising: (a) moving a strip of metal into a forming means; (b) forming the strip into a tube with the longitudinal edges of the strip being in edge contact; (c) disposing a

A method for the manufacture of a metal tube having two layers of plastics materials coated on the internal surface thereof, comprising: (a) moving a strip of metal into a forming means; (b) forming the strip into a tube with the longitudinal edges of the strip being in edge contact; (c) disposing an extrusion nozzle, having an elongated projecting portion, into the formed tube; (d) seaming the formed tube at the said edge contact; (e) providing a first and second source of flowable plastic material, each source having communication with the said nozzle, and the first source of plastic material being grafted polyethylene polymer and the second source of plastic material being another polymer; (f) extruding the first and second plastic materials through respective orifices in the said nozzle such that concentric tubular forms thereof are produced, and wherein the first plastic material surrounds the second plastic material and forms an outer concentric tube; and (g) urging the first and second plastic materials radically outward whereby the first plastic material contacts the inner surface of the seamed tube and bonds thereto and the second plastic material contacts the first plastic material and bonds thereto.