Method of production of high-pressure seamless cylinder from corrosion-resistant steel

Abstract

Blank of corrosion-resistant steel is coated with coating of water glass with thickness of 20 to 150 μm, cured at 15 to 60° C., and heated in an induction furnace to the temperature of 1180° C. to 1260° C. The heated up blank is without cooling by water descaling transferred into an extrusion press and extruded here, while the coating is broken to pieces and largely removed. Drawing in a horizontal drawing press and necking are performed. After forming to the final shape of the cylinder, leftovers of coating are removed by pressure blasting. A corrosion-resistant thin-walled seamless high-pressure cylinder with volume of 5 to 260 litres is manufactured.

Description

TECHNICAL FIELD[0001]The invention relates to the field of material forming, namely the method of production of high-pressure cylinder from corrosion-resistant steel using the method of hot backward extrusion solved completely specifically for the possibility to obtain high-pressure seamless cylinder not showing hydrogen embrittlement to and inner surface corrosion.BACKGROUND ART[0002]High-pressure seamless steel cylinders are currently produced using the method of backward extrusion and drawing utilizing the process according to the CZ pat. 243247.[0003]When using the procedure according to the CZ patent 243247, steel blanks are first cut from billets of square or circular section. The steel blanks are heated in an induction furnace to the output temperature of 1000 to 1250° C., after which they are robotically transposed into a descaling device where a high-pressure water jetting is performed to remove the scales from the surface of blanks. Then each individual blank is inserted b...

AI Technical Summary

Benefits of technology

[0016]The invention is utilizable for manufacturing of seamless high-pressure cylinders. It makes possible to manufacture these cylinders from corrosion-resistant steel and that in the corrosion-resistant version, even for larger and high cylinder volumes from 5 to 260 litres. The invention makes possible to manufacture these cylinders in the thin-walled version from significantly wider range of high-strength corrosion-resistant steels than the existing methods. Using this invention, substantial reduction of the mass of high-pressure cylinders is achieved as compared to the present state of art, and savings of material for their production. The seamless thin-walled version with these volumes was not possible so far. The cylinders according to the invention exhibit high mechanical resistance as well as pressure resistance. They have relatively very low mass, which as compared to the present state of art facilitates manipulation, storage, as well as transport. As compared to cylinders currently manufactured for example for scuba diving, respirators, for calibration gases etc., the cylinders according to the invention are by as much as two thirds lighter. The option to use corrosion-resistant steel for the production makes possible to use these cylinders even for raw natural gas and for gases and mixtures that in the case of existing cylinders from common chrome-molybdenum steel are causing hydrogen embrittlement and accelerated corrosion when reacting with the gas under high pressure.

Problems solved by technology

Disadvantage of the existing procedures of production of high-pressure seamless cylinders is the fact that they do not allow production of cylinders from corrosion-resistant steels using the method of backward extrusion and drawing, because the corrosion-resistant material degrades when conventional method of backward extrusion and drawing is used and it is impossible to produce safe high-pressure seamless cylinder from it.

In a seamless form, however, only double-necked cylinders of a simple shape can be manufactured with these procedures, because they do not allow seamless closure of the bottom.

However, because it is not possible to produce sufficiently thin-walled tubes as the starting semi-product for these procedures, all such pressure bottles made using production methods based on pipes have thick-walled structure, and thus they have considerable disadvantage in a very big mass.

Especially in the case of bigger and big volumes, such big weight of cylinders complicates handling, storage, and transportation.

Existing thick-walled cylinders have another disadvantage in low strength.

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