Method and apparatus for producing steel-plastic composite pipe

Abstract

The composite steel/plastic pipe producing process includes longitudinally bending or spirally winding steel plate with holes and welding to form metal pipe skeleton, separating the welded metal pipe skeleton from atmosphere with inert air, extruding the core layer plastic pipe inside the metal pipe skeleton, extruding the outer layer plastic pipe outside the metal pipe skeleton and making the inner layer and the outer layer of plastic pipe combined into one integral via the holes in the metal skeleton. The present invention also provides one composite steel/plastic pipe producing line. The produced composite steel/plastic pipe has high bearing capacity and firm combination of the inner and outer plastic layers.

Description

Technical field: [0001] The invention relates to a production method of a steel-plastic composite pipe, in particular to a method of using an inert gas protection device to isolate the welding seam from the outside air at the welding place of a cylindrical metal skeleton with holes from the welding point along the welding seam to prevent Oxidized layers are formed on the inner and outer surfaces of the welding seam, and the production method and device of compounding the adhesive layer, the core layer tube and the outer layer tube on the inside and outside of the cylindrical metal frame with holes respectively. Background technique: [0002] There are many methods and devices for the production technology of steel-plastic composite pipes, as well as corresponding patents, which use a metal skeleton with holes as a reinforcement, and extrude a composite polymer material on the skeleton as a continuum to wrap the skeleton to form a steel-plastic composite pipe. The reports and...

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Problems solved by technology

This kind of pipeline not only has the higher pressure bearing capacity of metal pipelines, but also has a plastic inner and outer wall and connects the inner and outer walls through the holes of the metal skeleton, so it has better anti-corrosion performance and pipeline connection performance. It is compatible with metal pipelines and Compared with pure plastic pipes, it has better comprehensive performance, and has been widely used in chemical industry, oil transportation, gas transportation, pressure transportation and corrosive media. It is a better structural composite pipe, but according to the above patents In the technical schemes, the molten polymer continuum passes through the holes of the metal skeleton to form the inner and outer pipe walls at the same time. This molding method has great defects. The molten polymer continuum turns over to The other side is melted and combined with each other. The turbulent flow of the polymer over the metal skeleton will leave a lot of residual stress in the cooled plastic pipe wall, which will lead to easy cracking during the use of the pipe and reduce the service life of the pipe. And this flow mode will destroy the thin layer of adhesive layer that is extruded or sprayed or covered on the inner and outer surfaces of the metal skeleton, especially in the pores, resulting in a direct bond between the polymer continuum and the metal skeleton surface rather than through bonding. The agent layers are firmly combined with each other, while the polymer continuum is a non-polar surface, and the metal skeleton surface is a polar surface, the two cannot really be firmly combined with each other, resulting in mutual delamination during transportation or installation or use , In addition, the temperature of the polymer mutual fusion bonding surface is lowered due to the crossover of the metal skeleton, which also affects the reliability and strength of mutual fusion bonding

Patent 00100446.8 discloses a steel-plastic composite pipe forming device, including an inner pipe extruder, an outer pipe extruder, a glue coating device, a steel strip coil forming device and a steel strip coil welding machine. The device can produce There is a steel-plastic composite pipe with inner and outer plastic pipe walls and metal steel plates bonded together. However, there is a big defect in the welding method of the steel plate seams in this technical solution, that is, the temperature of the weld seam is very high after welding, and no

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