RU27825U1 - TECHNOLOGICAL LINE FOR THE PRODUCTION OF COATED METAL - Google Patents

Description

Coated Cast Metal Production Line

The utility model relates to metallurgical production, namely to the production of vacuum steel with subsequent metal processing by pressure, non-mechanical methods and can be used in diffusion surface treatment of metal products, in particular for applying a protective coating in bathtubs with molten zinc and other liquid metals on a steel strip .

Hot galvanizing, as a rule, is subjected to products from low carbon and low alloy steels with a carbon content of 0.5-0.24% C.

Carbon is an essential element that determines both the structure and properties of steel, its strength and behavior during operation. It can affect the reaction of steel with liquid zinc and ultimately the structure, thickness and properties of the resulting zinc coating. It has been established that under the same galvanizing conditions, the thickness of the zinc coating layer on carbon steels containing more than 0.15% carbon increases by about 10% compared with steels containing less than 0.1% carbon.

Recently, vacuum coated steel with an ultra-low carbon content of up to 0.002% has been used for zinc coating. At the same time, the ductility of products of the exhaust category CB and OSV according to GOST 9045-80, which is necessary for the production of automobile sheets, is achieved. High ductility is required for stamping complex parts.

IPC 23 C 2/06; C 21 C 5/28; C 25 D 3 / 22-3 / 21; At 21V

forms. Therefore, the production of vacuum steel with a low 5-carbon content allows you to get closer to competitive products.

A well-known steel production line, which includes a converter, wax machine, a ladle furnace and a slab continuous casting machine, (see V.I. Shor, Oxygen-Converter Shops of Foreign Metallurgical Plants, // Steel-Casting Production: Sat. "Overview articles / Inst. t. Chermetinformation. M., 1987.)

The disadvantage of this analogue is a large number of complex, non-modern equipment.

Also known is a production line consisting of three "series-connected industries: smelting, ladle and metal casting. The sintering plant consists of a converter and a vacuum vessel, a bucket from the ladle furnace, and a casting unit from continuous casting machines (see RF certificate for utility model No. 17781, MIC 21 C 5/28).

The disadvantage of this line is the narrow range of steel produced, its lack of competitiveness to meet the needs of the expanding cold-rolled metal market.

Coating equipment is known which is included in the production line: a rolling mill, a unit for preparing a metal surface for zinc coating, and a unit for continuous hot-dip galvanizing (see E.V. Proskurkin, V.A. Popovich, A.T. Moroz " Galvanizing, Metal 5 Phygia, 1988, pp. 134-215).

The disadvantage of the described line is, low productivity, insufficient quality coating, non-zincing, roughness due to the poor quality of the tack. Hence the lack of properties of galvanized metal, necessary for use in the automotive industry, for example, such as corrosion resistance.

Closest to the claimed production line is a production line for producing galvanized steel, including a metal processing mill, a unit for preparing the surface of the tape for galvanizing, a unit for continuous hot galvanizing with equipment for coating, equipment for monitoring the quality of galvanized tape, and devices for completing the finished production , automated process control systems, (see J. “Steel, 1999, No. 11, pp. 45-46“ Improving the corrosion resistance of galvanized steel).

A disadvantage of the known production line is the low productivity due to the lack of new capacities, the uniformity of the assortment of products, low wear resistance, low mechanical and operational properties, and non-competitive products. In addition, there are no modern quality control systems and adjustments to the production program.

The task to which the claimed utility model is directed is to expand the technological capabilities of the line units, increase its productivity, obtain high-quality products with properties for the production of automobile sheets, and the competitiveness of metal products.

The technical result is achieved by producing steel with an ultra-low carbon content, by coating the metal with zinc, by achieving high ductility of the metal, and also by introducing new capacities.

The essence of the proposed utility model is that the line for producing metal with a coating, for example zinc, includes a converter connected in series and combined into a single transport circuit with top and bottom blowing; a vacuum chamber with nozzles and an upper lance for blowing oxygen, moreover, a suction metal nozzle

the vacuum chamber is equipped with tuyeres (up to 12 pieces) with the ability to control the flow of argon into the metal from below; the unit "ladle furnace, made in the form of a stationary equipped lid; slab continuous casting machines; strip hot rolling mill; continuous etching unit for preparing the surface of the tape for galvanizing; two-stand reversible mill; continuous hot dip galvanizing unit (ANGC) with coating equipment, which additionally contains a second galvanizing bath, and together with the first they are equipped with a transport and lifting system for moving the baths from line to line, a hardening device, a training unit with work rolls for achievement of the rolling force corresponding to; its various steel grades; a vertical type radiant furnace is installed as a heating furnace, and at the ANGC outlet there are installed as a minimum two winders with the possibility of winding the tape both from above and from below.

The processing line for producing coated metal is illustrated by drawings (Fig. 1 and Fig. 2.). In FIG. 1 shows a part of the production line: converter 1, vacuum unit 2 connected in series, ladle furnace 3, slab continuous casting machines 4, hot rolling mill 5. FIG. 2 is a continuation of the production line shown in FIG. 1. 6 - continuous pickling unit, 7 - two-stand reversing mill, 8 - continuous hot dip galvanizing unit, which has an input, technological and output sections.

The inlet section consists of an uncoiler 9, a welding machine 10, a preliminary cleaning unit 11, a loop drive of the strip 12. The equipment of the inlet section of the ANSC works with stops.

The technological section of the ANSC consists of an electrochemical cleaning unit 13 (Fig. 2), a vertical-type radiant heating furnace 14, a galvanizing bath 15, a cooling unit 16, a hardening 17, a training two or four roll mill 18, a tensioning machine 19, a passivation unit 20 .

The output section of the AGNC consists of a loop drive 21, a trimming machine 22, an electrostatic oiler 23, coilers 24.

The technological line for the production of coated metal works as follows. The steel from the converter 1 enters the vacuum vessel 2, which allows you to fill the vacuum steel with a particularly low carbon content (0.001-0.002%), then to the ladle furnace 3, then to the continuous casting machine 4, and then to the hot rolling mill 5.

Hot rolling mill 5, which contains methodological furnaces, rough and clean) G) groups of stands, feeds the metal wound into coils, to a continuously pickling unit 6, a hot-rolled pickled strip of non-alloyed and micro-alloyed carbon steel, rolled up for a two-stand reversing mill 7 into a roll. The roll should not have welds and coils. The edge of the strip should be trimmed, without any cracks along the edges and structural defects. Mechanical properties must satisfy the following requirements:

yield strength370-600

Temporary tear resistance 490-690

- maximum deviation of hardness ± 7%.

Strip sizes:

- bandwidth not more than 1650 mm;

- strip thickness not more than 5.0 mm;

- thickness tolerance ± 7%;

- deviation from a flat plate more than 15 mm / m.

Sizes of a roll:

not less than 1000 mm;

not less than 1.5 mm;

-inner diameter610mm;

-Mass rollan more for ANGTS 35t.

The profile of the strip should have a parabolic shape with a maximum increase in thickness of 30-70 microns, measured in the center and 40 microns from the edge of the strip. The deviation of the thickness from edge to edge (asymmetry of a parabolic shape) should be on average zero, but not exceed 30-50 microns, depending on the width of the strip.

The surface of the strip must be uniformly etched without any inclusions, rough scratches and sealed foreign bodies. This strip is the starting material for the ANGC.

The movement of the strip at the ANGC begins with the task of the roll on the unwinder 9 (Fig. 2) and preparing its front end for welding on the welding machine 10. The welding machine can operate with a maximum thickness difference and a maximum difference in strip width of 300 mm. Welding of the ends of the strip is done automatically.

After welding, the portion of the strip with the weld is mixed onto the inspection table, where the quality of the seam is evaluated. At the same time, a strip tension is created in the weld area, after which the operator makes a visual assessment of it. Upon detection of complete or partial destruction of the weld, the welded section of the strip is fed back to the welding machine, where the defective weld is cut and the welding cycle is repeated. The complete welding cycle from the stop of the line at the ANGC inlet to its start-up is 45-60 seconds.

If by the time of the complete selection of the strip from the input drive 8, the ends of the stripes are not welded, then the unit automatically stops. After welding the strips, the required voltage is created, the equipment of the input section is accelerated to a speed exceeding the speed of the strip in the technological section, and a reserve of the strip is collected in the input drive 8 to ensure continuous operation of the unit when

next cycle. After filling the input drive, the speed of the input and technological sections are synchronized.

The operation of cleaning the strip is carried out to remove contaminants from its surface formed during rolling, and includes: chemical, chemical-mechanical (processing in an alkaline washing machine with feeding streams of hot degreasing solution), electrochemical and mechanical cleaning (with feeding to strip of hot water).

The strip cleaning is carried out in two stages, while the strip passes sequentially through the cleaning baths in the following order. Pre-cleaning before the input drive is carried out in the pre-cleaning unit 11 in front of the input drive 12. The pre-cleaning unit is an alkaline chemical cleaning bath by immersion. Then, a stream of hot alkaline solution is supplied to the strip, after which the strip is washed with a stream of hot water and dried with hot air. The main cleaning is carried out after the inlet loop accumulator 12 in the technological section of the ANRC in the electrolytic cleaning unit 13 and begins with an alkaline chemical cleaning bath by immersion, then the strip enters the alkaline washing machine with a stream of hot alkaline solution injected into the strip, after which the strip is immersed in the bath electrochemical cleaning, then a stream of hot water is again fed into the strip in a trace alkaline washing machine, after which the strip penetrates into the bath of jet washing of hot water, and then it is dried hot air.

Chemical and chemical-mechanical treatment of the strip, both in the preliminary APHC section and in the technological section, is carried out in degreasing solutions with a concentration of Na OH 10-20 g / l. Electrochemical cleaning is carried out in a solution with a concentration of Na OH 20-50 g / l. The temperature of alkaline solutions is 75-90 ° C. After preliminarily and mainly cleaning and washing the surface of the strip, it is dried: in air dryers.

heated to a temperature of 100-140 ° C. Heated air for drying the strip is carried out in steam heaters. Air is supplied to the strip under a pressure of 250 mm water column. with an air flow rate of 6450 m / h for the inlet section and 3870 m / h for the technological one.

After cleaning and drying the surface, the strip is fed to the furnace 14 for heat treatment - recrystallization annealing, providing its mechanical properties of the finished galvanized steel.

The vertical broaching furnace has three processing sections: a heating, holding and cooling section. In the first two sections, the metal is heated by gas W-shaped radiation tubes. In the last section, the strip is processed in jet cooling units.

The cooling of the tackle after heating and holding during heat treatment is carried out to ensure the temperature of the strip close to the temperature of the zinc melt in the zinc bath. The cooling of a galvanized strip in a vertical gauge when moving upwards occurs from 460 ° C to 285 ° C, and when moving down to a temperature of 160 ° C.

Coating equipment consists of two bathtubs 15c with the necessary equipment, equipped with a transportation and lifting system for moving bathtubs from line to line. For continuous coating of the steel strip, the bathtubs 15 are equipped with induction heating. Internal dimensions of the bath: length 4100 mm, width 3200 mm, with a depth of 2100 mm.

In the process of continuous hot dip galvanizing, in which the base metal is immersed in the molten coating metal, an alloy layer is formed on the contact surface of the metals as a result of diffusion. This layer provides the strength of the applied coating. The temperature of the galvanized strip should not exceed 290, during this time the crystallization of the zinc coating should completely occur and it should acquire sufficient mechanical properties. Thickness

The cover is adjustable after immersion. The main technology for adjusting the thickness of the coating is the gas extraction process, which provides a uniform surface without grooves, slags and thickenings. Quenching in a bath 17 with water to a temperature of less than 50 ° C is like fixing, or you can call fixing the structure that had been obtained before through all the operations described above.

The training mill 18 performs as if smoothing the tubercles by slight rolling with an elongation coefficient depending on the steel grade (from 0.3 to 1.8%). To achieve a rolling force corresponding to different grades of steel, two diameters of the work rolls are necessary.

In the correct tensioner 19, the strip is stretched by adjusting the speed of the strip tensioner at the outlet with respect to the speed of the strip tensioner at the inlet so that the drawing coefficient is constant. The elongation is 0.62.0%, depending on the steel grade and strip size. Editing of galvanized steel is necessary to increase its flatness.

In the passivation (chromatization) section 20, the galvanized strip is passivated in a solution of chromic acid or in an acidic solution of chromium IV salt. Passivation is necessary to protect the zinc coating from corrosion during transportation and storage. The contact of zinc with this solution causes a chemical reaction, which results in the formation of a conversion layer of complex chemical composition: it contains zinc oxides and hydroxides, zinc chromate and a mixture of oxides and hydroxides of chromium III and chromium IV. When chromated zinc comes in contact with a corrosive medium, chromium IV is released as chromates, which are corrosion inhibitors.

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through the second loop drive 21, then through the trimming machine 22 and then into the electrostatic oiler 23. The latter provides uniform coating of the strip with oil.

The surface density of the oil film on each side of the strip is 0.5-2.0 g / m. Oil temperature in the supply tank to the sprayers up to 70 ° С.

For oiling, two types of concentrated oils are used in agreement with the consumer:

1) oil with protective properties in relation to the zinc coating;

2) oil, which, along with protective properties, will further ensure the stamping of products from galvanized steel without the use of additional grease.

Galvanized metal or finished products in strips are wound into rolls on coilers 24 and packed on the packaging unit in rolls, as well as in sheets cut and packed on the transverse cutting and packaging unit. Rolls from coilers are transferred to a transfer trolley, and then they are stored in a warehouse using an overhead crane.

Galvanized metal control is carried out before winding into coils and includes: flatness check on a horizontal table; inspection of the surface of both sides of the sheet at the visual inspection station; measurement of rolled thickness by X-ray thickness gauge; measurement of the width of galvanized steel.

Using the proposed technological line for the production of coated metal in comparison with the known one allows to increase the productivity of the line by creating new capacities (steel finishing unit, two-stand reversible cold rolling mill), to obtain better and more competitive products by expanding the range of smelted steel and organizing the production of the latest types of cold-rolled sheet of IF steel with an ultra-deep exhaust, as well as due to the installation of quenching and wood aggregates in the AGSC scaling, with the properties necessary for the automotive industry and corresponding to GOST 19904-90 and GOST 9045-93.

In particular, in accordance with GOST 9045-93, the requirements for the stampability of a sheet of categories of VG (very deep), CB (complex hood) and WWS (particularly complex hood) categories are expressed in ferrite grains. They are 6-9 points. In our research, these numbers were 6.7 and 8 points. Another two main indicators for a metal suitable in the automotive industry are the ratio of the yield strength ct to the ultimate strength Op,

that is, u and Brinell hardness.

in a laboratory study of galvanized sheet according to

the inventive production line, the ratio of y for SV was 0.7,

and for WWS no more than 0.66. The indicator 0.66 meets the requirements for the automotive industry.

The Brinell hardness in laboratory tests was 44 in one case, 45 in the second, and 46 in the third. For a car sheet, it should not exceed 46.

Thus, based on the indicators above, the galvanized sheet obtained in accordance with the claimed utility model is of high quality, quite competitive for promoting it on the automotive market.

Claims (1)

A technological line for the production of metal with a coating, for example, zinc, including an adjacent metal processing mill, a unit for preparing the surface of the tape for the corresponding coating, a unit for continuous hot galvanizing (ANGC) with coating equipment, a galvanized tape quality control system, and devices for the acquisition of finished products, automated process control systems, characterized in that the production line is additionally equipped with unity series converter with degasser nozzles, the unit "ladle furnace" slab continuous casting machine, dvuhkletevym reversing mill, while the suction pipe metal degasser tuyeres is equipped with the possibility of feeding argon into the metal bottom regulation; a hot rolling mill is installed as a metal processing mill, a continuously pickling unit is installed as a unit for preparing the tape surface for coating, after which a two-stand reversing mill is located, and coating equipment, for example, zinc, additionally contains a second galvanizing bath, and together with the first they are equipped with a transportation and lifting system for moving the bathtubs from line to line, a hardening device, a training unit with work rolls to achieve power For rolling, corresponding to various steel grades, a vertical type radiant furnace is installed as a heating furnace, and at the exit from the ASCC, at least two winders are installed for winding strips with the possibility of winding the latter both from above and below, with all the units making up technological line, combined into a single transport circuit.