Rolling mills at the Novolipetsk and Cherepovets metallurgical plants. Rolling of metal in roughing and finishing groups of stands Pair Cross

Primetals Technologies was the first company in the world to develop a slab sizing press, and to this day it remains a leader in this field. Based on our rich experience, we have made significant changes to the design of the slab sizing press, resulting in

• further reduction in width: max. 350 mm
• increase in the productivity of the slab caster,
• increase in yield,
• as well as the development of performance to reduce the amount of time required for modernization (or installation)

Improved intermediate rewinder

The coilbox is installed between the roughing and finishing stands for rewinding the roll after the roughing stands. The installation of such a winder makes it possible to reduce the distance between the roughing and finishing group on the new mill and to minimize the drop in temperature of the rolled material fed to the finishing group. In addition, the drumless rewinder also does not allow a significant temperature drop on the internal windings of the roll compared to the drum winder. The drumless rewinder also has room for side heat shields, which are involved in preventing temperature drops at the edges of the roll. The coiler, developed by Primetals Technologies, has two modes of operation. One of them is passive, when no active mechanical actions are performed - this is a simple method of work. The second mode of operation is the forced roll transfer mode. The boost system ensures fast and reliable roll transfer and higher productivity.

• Prevention of temperature drop on the internal turns of the roll when using a drumless rewinder
• Prevention of temperature drops at the edges of the bale due to the presence of adjustable side heat shields
• Increased productivity due to short winding, which is achieved due to the increased winding speed and the forced transfer of the roll from the winding position to the unwinding position
• Stable operation of the finishing group is ensured due to the uniformity of temperature distribution along the entire length of the roll. Thanks to this, rolling with acceleration in the finishing group is not required.
• The mode of passing through the rewinder without winding is possible, if there are appropriate requirements for productivity and for the production method
• The rewinder can be used for a wide range of roll sizes in the production of a wide range of carbon and stainless steels.

Trimming shears with different drum speeds

At the roll, after leaving the roughing group, ends in the form of the so-called "tongue" and "fishtail" are formed in the head and tail parts. Trimming shears are installed in front of the finishing group to trim the ends of the strip to ensure the reliability of threading the strip. The multi-speed disc side trimmer from Primetals Technologies is a unique tool. Shears consist of upper and lower drums of different diameters with different linear speeds. During rotation, the position of the knives relative to each other alternately changes (positions "plus" - "zero" - "minus"), which gives a number of operational and economic advantages.

• Due to the alternating change in the positions of the knives relative to each other, an improved profile of the ends of the roll is formed
• Reduced wear and increased blade clearance increases blade life
• Possibility of cutting edges with minimum tolerances of at least 20 mm. This feature, together with the optimization system, can drastically reduce trimming losses.
• Reliable design and high torsional rigidity due to the use of synchronizing devices at the ends of the drum shafts between the upper and lower parts
• Quick blade change with hydraulic spreading system (option)
• Quick drum change (option)

Cage with crossed windrows in the horizontal plane Pair Cross

Primetals Technologies is the first company in the world to develop the horizontal cross section mill, which offers many options for controlling the cross-sectional profile of the strip. To date, we have maintained a leadership position in this area, in addition, Primetals Technologies, using all its extensive experience in metallurgy, has developed a number of improvements to this system.

• Strip shape control
• Simplified design
• Achieving high reduction ratios
• Reduced mill vibrations with the use of a stand stabilization device (MSD)

Rolls SmartCrown

SmartCrown work rolls provide a modified sinusoidal contour. By choosing the correct contour coefficients and making the axial shift of the work rolls the same distance in opposite directions, we always get a cosine form of the roll gap, regardless of the actual position of the roll shift.

Stands with axial shift of work rolls

Primetals Technologies was the first to develop the work roll axial shift stand and continues to be the industry leader today, and we have greatly improved this technology based on our extensive experience in the metallurgy. Primetals Technologies uses work roll axial shift in hot strip production to accomplish two things:

• Uniform distribution of work roll wear
• Strip flatness control (SmartCrown), see detailed description below:

Stand Stabilization Device (MSD)

In the complex realities of today, maintaining a stable operation of a rolling mill is becoming more and more difficult. The stand stabilization device is a hydraulic cylinder installed in the frame opening and pressing the roll pads with a constant force. The device allows you to remove the gap between the pillows of the rolls and the frame, maintains the rolls in the correct position and stabilizes them.

• Provides stable rolling in difficult conditions
• Stabilizes strip threading
• Reduces the amount of work to adjust the roll gap in the frame opening (simplifies maintenance)
• Prevents problems arising from misalignment of work and back-up rolls
• It is possible to install on an existing mill

In-Line Roll Forming Unit (ORP)

Primetals Technologies was the first to develop roll grinding in a mill line and is still a leader in this field, and we have greatly improved this technology based on our extensive experience in the metallurgy.

• Extended roll life
• Elimination of surface defects of rolls
• Increasing the rolling length of a single width product
• Possibility of transition to a larger width without reloading rolls

Loop profiler (LSM)

Measuring the strip profile between mill stands has always been difficult and highly unreliable. Primetals Technologies has developed a looper profilometer for continuous and accurate measurement of sheet geometry between stands. The LSM profilometer has a number of advantages:

• The load on the rollers of the segments is measured using a torque sensor without taking into account the influence of hysteresis, in contrast to the method when a load cell is used
• Measuring with a torque transducer gives higher accuracy and increases reliability without the influences caused by changing mechanical conditions
• Ease of replacement on existing loopers. Since the profiler has a low moment of inertia, the existing looper drive system can be used.
• Easy replacement of segment rollers during maintenance

power cooling. Enhanced strip cooling system

Hot rolling mills are often limited in their capacity and flexibility to produce advanced high strength steels (AHSS) such as API X80/X100, duplex, martensitic and multiphase grades.
. Therefore, Primetals Technologies has developed Power Cooling technologies for cooling and special metallurgical processing of rolled products "in line". This technology combines the advantages of traditional laminar cooling or "low pressure cooling" and "high pressure cooling" with the highest cooling intensity, resulting in greater versatility in operation.

Equipment. Advanced Cooling Technology

Enhanced cooling technology can be applied in the initial stages of cooling, in the area between the roughing and finishing group, between the stands of the finishing group and at the end in the cooling section on the roller table. Various cooling modes can be configured as shown in the diagram below. The Power Cooling unit can be installed on existing units using the existing water treatment plant, tank and piping. The water supply to the Power Cooling unit is carried out through a booster pump, which creates the necessary working pressure. The second variant of operation, that is, operation in the laminar cooling mode, involves bypassing the pump and supplying water directly to the collectors of the enhanced cooling system from a pressure tank. Thus, after the installation of the enhanced cooling system, the possibility of using laminar cooling over the entire length of the strip to be cooled remains.

Application

The use of enhanced cooling is not limited to thick strip (> 18 mm), which requires a high cooling intensity. With advanced water flow control and thus heat transfer control, this system is also applicable to strip where the combination of strip thickness, rolling speed and cooling requirement is particularly important. In addition, Power Cooling is used for the production of standard steel grades, since this technology can be used with Power Cooling technology in laminar mode. The combination of enhanced Power Cooling with laminar cooling is the ideal solution for cooling lines. The application of this system is very wide, as it allows you to optimize both the current assortment and adjust the operation of the equipment to future requirements.

Typical characteristics of Power Cooling technology

• Significant increase in cooling intensity compared to laminar/turbolaminar cooling
• High heat transfer coefficient up to 5 MW/m²
• Wide flow control range for maximum metallurgical flexibility

alloying

Force cooling provides an opportunity to reduce alloying costs by allowing hardening additives to be replaced by hardening due to higher cooling intensity.

Advantages

Power Cooling by Primetals is a state-of-the-art strip cooling technology

• Provides exceptionally high cooling rates (up to 40K/s for 25.4mm)
• Wide control range - from 10% to 100%
• Application for all units of assortment, since it is possible to work in two modes - laminar and enhanced Power Cooling
• Installed on both existing and new mills in combination with laminar cooling for bar cooling or in the inter-stand cooling zone
• The ideal solution for two-stage cooling, which is required, for example, for two-phase steels
• Suitable for increasing the capacity of short cooling lines

Improved winder model

Primetals Technologies offers a coiler whose design features include updates based on our experience.

• Wedge-shaped rocker drum with stepless expanding mandrel for excellent winding quality and high reliability
• Modular design allows for quick drum changes
• Automatic roller runout control prevents markings on the first inner coils of the roll
• Precise adjustment of side guides and pinch rollers ensures stable operation and roll quality

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MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION

FEDERAL STATE BUDGET EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION

«Magnitogorsk State Technical University named after G.I. NOSOVA

DEPARTMENT OF MATERIAL PROCESSING TECHNOLOGIES

PRACTICE REPORT

PRODUCTION TECHNOLOGY ON THE MILL G/P 2000

Magnitogorsk

Introduction

1.3 Production technology

2.2 Bandwidth measurement

2.3 System description

2.6 Meter verification

2.7 Curvature option

List of used literature

Introduction

The aim of the project is to increase product quality by introducing a DigiScan XD4000 stereoscopic width gauge at MMK's hot rolling mill 2000 at Rolling Shop No. 10.

The modern development of the production of rolled products is aimed at reducing energy costs, metal losses and improving the quality of metal products. The work under consideration will improve the accuracy of the results of monitoring the properties of hot-rolled steel. This will reduce the number of products erroneously certified as good, which will lead to a reduction in production costs in the entire technological chain and metal losses due to transfer to non-conforming products.

As a result of the proposed measure at mill 2000, the reliability of rolled quality control is expected to improve. This, in turn, will lead to a decrease in the likelihood of shipment of erroneously good products and acceptance of defective rolled products. Improving the quality control of the shop's products will also have a positive effect on the technical and economic indicators of the shop's products sold.

The proposed measure will allow not only to control the quality of rolled products, but will also contribute to the further improvement of rolling mill management methods.

1. Production technology at the mill with a capacity of 2000 OJSC MMK

The wide-strip hot rolling mill 2000 of the sheet-rolling shop No. 10 of OJSC MMK, adjacent to the continuous casting section of the converter shop, is designed for hot rolling of sheet steel.

1.1 Brief description of the main and auxiliary equipment

Wide strip hot rolling mill 2000 consists of:

loading area;

section of heating furnaces;

draft group of stands;

intermediate roller table;

finishing group of stands;

mill harvesting line.

A detailed layout of the equipment in the mill line is shown in Figure 1.1.

Loading area consists of a slab warehouse (SCC), a loading roller table, three lifting tables, tables with pushers, three transfer bogies and two scales. Area of ​​heating furnaces consists of three method type heating furnaces, a loading roller table in front of each furnace, a receiving roller table after the furnaces, slab pushers against the furnaces and slab receivers from the furnaces. Draft stand group includes a vertical scale breaker (VOL), a horizontal stand "DUO" and five universal stands "quarto", with the last three stands combined into a continuous group. Only one pass is made in each cage. Intermediate roller table equipped with encopanel type heat shields and undercut cutting pocket.

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Finishing group of stands includes flying shears, a finishing roller scale breaker, seven quarto stands (7 - 13) equipped with hydraulic pressure devices. All inter-stand spaces are equipped with devices for accelerated cooling of the rolled strip.

harvesting line includes two winder sections. Where each section has a group of coilers (in the first group - 3 coilers, in the second group - 2 coilers), a discharge roller table with two showering devices in front of each group, as well as puller carts, binders, receivers and transporting roll conveyors with lifting and rotary tables , as well as two scales and a roll knitting machine on the first group of winders.

1.2 Basic requirements for finished products and workpieces

Range of finished products of the mill

The wide strip hot rolling mill (SHSGP) 2000 is designed for the production of strips from carbon and low-alloy steel grades, rolled into a coil weighing from 7 to 43.3 tons, of the following sizes:

thickness, mm - from 1.2 to 16.0

width, mm - from 700 to 1830.

The size range of the mill is presented in Table 1.1.

Permissible deviations in thickness and width and requirements for rolled products must comply with the requirements of GOST 19903-90 and the technical specifications of the customer.

Table 1.1 - Dimensional assortment of strips ShSGP 2000 according to GOST 19903-90

The assortment of the wide-strip hot rolling mill 2000 by grade and size composition is presented in Table 1.2.

Table 1.2 - Assortment of ShSGP 2000 by brand and size composition

steel grade		Normative and technical documentation	Roll thickness, mm	Strip thickness, mm
St 1 - 3kp, ps SAE 1006, 1008, 1009, 1010, 1012, 1015, 1017, 1019, 1020, 1021, 1022, 1023, 1025
St 1-3sp, St 3Gsp
08 - 20kp, ps, sp, 25		4041, 1577, 16523 all TU LPTs-4 and 7
St1 - 3kp, ps 08 - 20kp, ps
St1 - 3sp, 08 - 20		for HRC-5 and 8
St 1 - 3kp, ps SAE 1006, 1008, 1009, 1010, 1012, 1015, 1017, 1019, 1020
St 1-3sp, St 3Gsp
08 - 20kp, ps, sp, 25		4041, 1577, 16523 all TU LPTs-4 and 7
10 HNDP, 10HDP
30G, 65G, 7HNM,
08ps, 08kp, 08yu		for rolling
		galvanized
45.50 (analogue 12GS,17GS)		14 -101-364 - 98
St50-2, St52-3 (analogue 14G2, 15GS)
300W (analogue 14G2)
		relay steel
0402D, 0403D, 0404D		transformer steel

Rolled products are produced in sheets and are intended for the manufacture of straight-seam pipes. Quality requirements are established in TU 14-1-1950-2004. products meter equipment mill

Sheets are supplied in specific lengths in nominal thicknesses in accordance with table 1.3. The thickness, width and length of the sheets are indicated in the order. By agreement between the manufacturer and the consumer, it is allowed to supply sheets of other thicknesses.

Table 1.3 - Rated temporary resistance and thickness of rolled products

Strength class	Tensile strength, N / mm 2, (not less than)	Sheet thickness for pipes with outer diameter, mm
		7,0; 8,0; 9,0 10,0; 11,0; 12,0; 12,5; 14,0; 15,6; 16,0	9,0; 10,0; 10,0; 12,0; 13,0; 14,0; 15,0; 16,0; 17,0; 17,5	11,0; 12,0; 12,5; 13,0; 14,0; 14,3; 14,5; 15,2; 16,0

Limit deviations in sheet thickness - in accordance with the requirements of GOST 19903 for increased rolling accuracy. By agreement between the manufacturer and the consumer, it is allowed to produce sheets of normal rolling accuracy. Maximum deviations in the length and width of the sheets - in accordance with GOST 19903. The crescent of the sheets should not exceed 1 mm per 1 m of length or 12 mm for a length of 12 m. The deviation from flatness per 1 m of the sheet length must comply with the standards of improved flatness in accordance with GOST 19903. By agreement between the manufacturer and the consumer, it is allowed to produce sheets of normal flatness in accordance with GOST 19903.

Basic requirements for the workpiece

Continuously cast slabs coming from the CCC with the following characteristics are used as the initial billet on the mill 2000 :

thickness, mm - 250

width, mm - from 750 to 1850

length, m - from 4.8 to 12

weight, t - from 7 to 43.3.

In addition, the mill can also roll open-hearth slabs with characteristics according to OST 14-16-17-90.

The use of slabs as the starting billet has the advantages of more uniform heating and effective control of the rolling temperature, higher mill productivity, and higher surface and mechanical properties of the finished strip.

To ensure the high quality of finished products, slabs must comply with STP 101-98-96, including tolerances for geometric dimensions:

Thickness, mm - +10; - 5;

Width, % - ± 1;

Length, m - ± 60 (for slabs up to 9 m long);

± 100 (for slabs longer than 9 m);

Rhombicity (diagonal difference), mm - no more than 10;

Sickle shape (curvature in width), mm/r.m - no more than 10 mm per 1 m of the length of the workpiece;

Flatness, mm/r.m - no more than 20 mm per 1 m of the length of the workpiece.

Requirements for the quality of slabs do not allow longitudinal, transverse and mesh cracks, belts, bubbles, sagging, slag inclusions, captivity on the surface of slabs.

The appearance and number of defects in cast slabs are determined by the casting conditions, the chemical composition of the cast steel, the technological conditions of smelting, the geometric dimensions of the slab section, the design with the state of the CCM equipment (continuous casting machine), etc.

The technology for detecting surface defects in continuously cast slabs, their selective cleaning and delivery to the hot rolling mill 2000 is carried out in accordance with the technological instruction TI-101-ST-KKTs-10-95. Slabs that do not meet the requirements of STP 101-98-96 and OST 14-16-17-90 in terms of shape and size are not fed to loading devices and are not subject to landing.

1.3 Production technology

Each melt (batch) of slabs is supplied with a certificate (consignment note) prior to being put into the furnace, which indicates the melt number, steel grade, dimensions of slabs, their quantity, total mass of metal supplied, purpose of strips and, if necessary, additional requirements according to the standard, as well as the nature Posada (cold or hot).

The supply of metal to the loading roller table is carried out in two ways: "in transit", that is, along the roller table directly from the CCC and through loading trolleys.

When metal is fed through the loading carts, the operator controls the correct stacking of the slabs: the slabs must be laid evenly, not shifting from the carts, they must be freely removed by the lifting table and the possibility of their fall must be excluded.

On the loading roller tables, each slab is weighed with automatic weight entry into the computer. The slab is considered accepted to the mill after it is weighed on the scales.

Slabs are heated before rolling at the 2000 wide strip mill in continuous walking beam furnaces. They provide heating of the metal to a temperature of 1250 - 1300 °C. The slabs are loaded into the heating furnaces strictly float-wise, evenly across the furnaces.

Before the slabs are planted in the furnace, slag, scale and other objects that interfere with the uniform heating of the slabs are removed from the metal surface with the help of special installations (brushes).

Slab planting is subdivided by temperature into hot - the temperature of slabs is more than 500 °C and cold - the temperature of slabs is up to 500 °C.

The planting of slabs in the furnace is carried out depending on their length in automatic mode as follows:

length 4670 - 6000 mm - two-row;

length 7870, 8370, 8470, 8730 - 9870 mm - staggered:

length 11000 - 12000 mm - single row.

If the slabs are seated incorrectly in the furnace (the slabs are displaced to one side as they move through the furnace), the seating is immediately stopped and corrective measures are taken.

The mode of metal heating in the heating furnaces of mill 2000 is given in the technological instructions for furnaces. Depending on the group and grade of steel, the minimum heating time of slabs during cold or hot fit and the heating temperature of slabs are determined.

The issuance of slabs from furnaces is carried out in strict accordance with the landing label and technological instructions for furnaces.

The slabs, heated to a predetermined temperature, are removed from the furnace and move along the roller table to the roughing group of stands.

The first compression is carried out in a vertical rough scale breaker (VOL) located in front of the rough stands. With this compression, the width of the roll is calibrated and the scale on the surface is broken. In the future, the roll is crimped in the remaining stands of the roughing group (No. 1 - 6). The total reduction in the roughing stands is 80 - 90% of the reduction in the mill, partial reductions in the stands - up to 40%.

From the VOL, the slab enters the DUO horizontal stand and then sequentially to the stands No. 2, 3, 4, 5, 6. The DUO stands No. 2, 3 have main drives with constant speed motors (synchronous).

Stands No. 4, 5, 6 are combined into a continuous subgroup, where it is important to ensure a consistent rolling regime (without backwater or tension) in order to avoid increasing the load on the rolls and drives of the stands. The vertical stands run at a linear speed equal to the speed of the next horizontal stand with reduction correction.

The speeds of the roller tables are synchronized with the speed of rolling and control, depending on the position of the roll.

The rolling stands are equipped with metal pressure sensors on the rolls (mesdoses). Photorelays installed in the rolling line monitor the progress of the rolled strip. Pyrometers are installed behind stand No. 2 and at the exit from the roughing group to measure the temperature of the rolled product in the rolling line. The temperature of the strip after the 2nd stand is 1100–1200°C, and after leaving the 6th stand it is 1000–1100°C. The rolling speed in the stands is 5.0 m/s.

After the roughing group, the roll moves along the intermediate roller table to the finishing group of stands, where the rolled strip is located simultaneously in several stands.

The intermediate roller table is equipped with an encopanel-type heat shield, a pocket for cutting underrolls and an underroll pusher.

To maintain the temperature of the roll and reduce the difference between the head and tail of the strip, thermal screens of the enkopanel type are used.

In cases of strip jamming in the finishing group or in winders, the underrolled strip remaining in the gap collides into the pocket for cutting underrolls. (Nedokat - a slab rolled in one or more stands of the roughing group).

The ends of the roll obtained in the roughing group of stands have an irregular shape, a smaller thickness and a lower temperature compared to its main length.

In order to avoid such phenomena, as well as to better capture the roll by the wolves, flying shears are installed in front of the finishing group of stands to cut the ends of the roll.

The speed of the strips when cutting with flying shears of the rear end is 0.4 - 2 m / s, the front end is 0.6 - 1.5 m / s.

In the process of transporting the rolled metal along the intermediate roller table, a layer of secondary (air) scale is formed on its surface, which is cracked in the finishing scale breaker.

The total reduction in the finishing group of stands is 10 - 20% of the total reduction for the entire mill. The applied reductions are successively reduced from the first stand to the last.

To improve the accuracy of strips rolled in the finishing group of stands, the mill is equipped with a local automatic control system for thickness (SART), transverse profile and shape of the strip, tension (SARN), temperature at the end of rolling, operating as part of the process control system of the mill and shop.

To stabilize the process, rolling in the finishing group is carried out with interstand tension, which is chosen to be minimal in order to eliminate the effect of tension on the distortion of the transverse profile of the strip in the interstand gaps. Strip tension is used as a technological factor that ensures the stability of the rolling process and the position of the strip on the mill

A necessary condition for the stabilization of rolling in a continuous group is the constancy of the second volumes of metal over the stands, which, taking into account the practically unchanged strip width in all stands, can be written as:

Where h - strip thickness;

v - rolling speed.

It is possible to operate the finishing group with one to two stands removed from the rolling process. The temperature of the strips behind the 13th stand is 750 - 950 °C. The rolling speed in the stands of the finishing group is 18 - 20 m/s.

To ensure the necessary mechanical properties of the metal and to observe the temperature regime of the winding, the strips are cooled with water using shower systems located on the discharge roller table in front of the first group of winders and in front of the second.

Strips are subjected to cooling depending on the steel grade and purpose according to the relevant modes.

The strips rolled on the mill are wound into coils with a diameter of up to 2500 mm by coilers of the first and second groups (depending on the thickness of the coiled strip).

The temperature of the strip during winding should be 500 - 750 °C. The maximum strip winding speed is 21 m/s and the filling speed is 12.5 m/s. The winding of the strips into coils on the hot rolling mill 2000 is carried out differentially: on the coilers of the first group (No. 1 - 3) they accept strips with a thickness of 1.2 - 3.0 mm, on the coilers of the second group (Nos. 4, 5) they accept strips with a thickness of 2.8 - 16.0 mm. It is also allowed to wind up strips up to 4 mm on winders of the 1st group, and from 2 mm on the 2nd group. Winder control both manual and automatic.

Reeling of the cooled strips should be carried out on the last winders in each of the two groups - No. 3 and 5.

The strips wound into a roll on the first group of winders are tied with a roll knitting machine and weighed. For tying rolls, a packing tape with a cross section of 0.8 × 31 mm is used in accordance with STP-101-128-97. After weighing, the rolls move along the conveyors to the turntable and then along the conveyor to the place where the rolls are marked without fail with the following data:

roll number and total number of rolls in a fusible batch;

fusible batch number;

steel grade;

strip size (thickness, width);

direction of shipment;

At the same time, the rolls are subjected to appropriate transport and technological cargo processing and information support.

1.4 Defects in the production of hot-rolled coils in Rolling Mill No. 10

The most typical product defects and ways to eliminate them are shown in Table 1.4.

Table 1.4 - Defects of the mill capacity 2000 HPC 10

	Definition	Cause	Troubleshooting Methods
	Unfinished rolling of slab, ingot, bloom, billet	1) Rolling of insufficiently heated slab, emergency stop of equipment, jamming of strips on the mill line.	1) Observe the technology of heating and rolling metal, monitor the serviceability of the equipment.
	Unrolled slab	1) Deformation of slabs in furnaces due to violation of the heating regime, incorrect planting pattern. 2) Incorrect fit of slabs.	1) Observe planting scheme and slab heating regimes. Avoid improper planting of slabs.
crescent	Bending of the form, in which the edges of the sheet or strip in the horizontal plane have the shape of an arc	1) Distortion of the horizontal rolls of the stands. 2) Large convexity of the barrel of the work roll due to incorrect profiling.	1) Correct setting of stands. 2) Proper selection of profiles, organization of sufficient cooling of the rolls and cleaning of the cooling collectors.
waviness	Deviation from flatness, in which the surface of a metal product or its individual parts have the form of alternating convexities and concavities.	1) Too large reductions in the stands, uneven reduction across the width of the strip. 2) Development of rolls due to non-observance of the order of rolling.	1) Unload or adjust the stands. 2) Cross the rolls, correctly plan rolling on the mill.
	Surface defect in the form of a groove without protrusion of edges with a rounded or flat bottom.	1) Non-working rollers of the discharge roller table, incorrectly installed wiring fittings ..	1) Set the correct level of plates, rulers and wiring fittings, monitor the condition of the roller tables.
boxiness	Non-flatness in the form of local bending of the sheet in the transverse direction, which is formed due to uneven deformation along the width of the workpiece.	1) Insufficient crimping in the stands, incorrect crimping mode. 2) Incorrect selection of roll profiling. 3) Uneven cooling (heating) of the roll barrel (nozzles of the roll cooling collectors are clogged or there is not enough water to cool the rolls). 4) Incorrect grinding of rolls.	1) Load the stand, redistribute reductions in the finishing group of stands. 2) Replace the rolls with rolls with reduced convexity or increased concavity of the barrel, select the correct profile. 3) Clean clogged nozzles, increase the amount of water to cool the rolls. 4) Correctly grind the rolls.
prints	Surface defect in the form of periodically repeating, grid-shaped protrusions resulting from the indentation of a rolled sheet or strip into cracks in worn rolls	The appearance of depressions in the form of a grid on the surface of the roll due to: 1) A large amount of rolled thin metal. 2) Use of rolls with worn-out bleached layer. 3) The height of the rolls when the bands get stuck in them.	1) Timely transshipment. 2) Timely transshipment. 3) Avoid jamming, timely transshipment.
Rolled in	Surface defect in the form of inclusions of scale residues pressed into the metal surface during deformation	1) Violation of the mode of heating slabs in continuous furnaces. 2) Clogged descaling nozzles. 3) Development of rolls of stands.	1) Do not violate the heating technology. 2) Timely checking and cleaning of the nozzles. 3) Timely transshipment of rolls.
Telescopic roll		1) Sickle stripe.	1) See point 3. 2) Winder setup.
imprints	Surface defect in the form of recesses or protrusions located over the entire surface or in separate areas.	1) For various reasons, the formation of depressions on the surface of the roll (pull roller), or crumbling of the roll (pull roller). Sticking of metal particles on work rolls, pulling or forming rollers. On rolled metal, the defect periodically repeats along the length of the roll.	1) Timely detection of a defect and transfer of rolls, pulling rollers or stopping the mill or winder to clean the roll or rollers with an emery wheel.
bundle	Surface defect in the form of cracks on the edges and ends of sheets and other types of rolled products, formed in the presence of shrinkage defects in the metal, internal ruptures of increased contamination with non-metallic inclusions	1) Violations of technology in steelmaking, the presence of shrinkage defects in the metal, internal ruptures, increased contamination with non-metallic inclusions. Also formed during burnout.	1) Prevent metal burnouts in heating furnaces and violations of technology at previous processing stages.
	A defect in the surface of a thin sheet in the form of a partially rolled-up fold located along or at an angle to the direction of rolling.	1) Deformation of varying degrees along the width of the sheet due to incorrect setting of the finishing stands of the mill.	1) Set up the camp.
Roll with pleats	A defect in the form of a roll, in which folds have formed in some sections of the coils of the strip, due to the presence of warping or crescent.	1) Inconsistency in the speed mode of winding. 2) Distortion of the pulling rollers of the winder. 3) Curvature of the strip.	1) Adjust the winder for speeds. 2) Adjust the pull rollers. 3) Eliminate warping.
Rip on edges.	Surface defect of the sheet and strip in the form of metal breaks on the side edges or on another part of the strip, formed due to a violation of the rolling technology, as well as during rolling of metal with reduced ductility	1) Violation of the modes of heating slabs before their rolling. 2) Excessive rolling reductions. 3) Rolling with free broadening without compression of the side edges. 4) Rolling of metal with strongly cold edges. 5) Rolling of metal with low technological ductility	1) Do not violate the heating regimes. 2) Evenly redistribute reductions over the stands. 3) Avoid rolling with free broadening. 4) Avoid overcooling of the edges by controlling the water supply to the mill lines. 5) Withstand chem. steel composition during smelting, observing the required ratio of manganese and sulfur.
Telescopic roll	Roll shape defect in the form of protrusions from the middle or inner part of the roll.	1) Sickle stripe. 2) Incorrect winder setting.	1) See point 3. 2) Winder setup.
Variation in thickness	Deviation of the shape, characterized by uneven thickness of metal products in width or length, beyond the plus.	1) Uneven heating of the slab. 2) Development of rolling rolls. 3) Incorrectly selected high-speed rolling mode in the finishing group of stands.	2) Timely transshipment of rolls. 3) Correct setting of stands for speed.
Deformation flaw	Defect in the form of an open fracture located across or at an angle to the direction of the greatest metal elongation during rolling	1) Reduced ductility of the metal, due to violation of the technology of heating slabs before rolling.	1) Do not violate the established modes of heating slabs.
	Deviation from the specified width to the smaller side in excess of tolerance	3). Mistakes in sizing.	3) Eliminate errors.
	Deviation from the specified width to the greater side in excess of tolerance	1) Incorrect setting of the vertical rolls on the mill. 2) Non-compliance with the tension mode between the stands of a continuous group. 3) Errors in the fabrication of sizes.	1) Properly adjust the rolls. 2) Maintain the strip tension mode. 3) Eliminate errors.
	Deviation from the specified thickness to the smaller side in excess of tolerance
	Deviation from the specified thickness to the greater side in excess of tolerance	1) Incorrect adjustment of the work rolls of the finishing group of the mill. 2) Uneven heating of slabs. 3) Rolling of strips held in the mill.	1) Set up the stands correctly. 2) Follow the slab heating technology. 3) Avoid emergency stops rolling.
	Surface defect, which is a rolled protrusion	1) Rolling of a slab with rough stripping marks. 2) Rolling peals with deep risks on the surface.	1) Observe the technology of stripping slabs. 2) Monitor the condition of the wiring fittings of the stands and rollers of the roller tables.
Inversion of the edge	Form defect in the form of local wrinkling of the strip edge or individual protruding turns of the roll.	1) Strong compression of the strip by the guide lines. 2) Oblique task of the strip in the guide rulers. 3) When capturing rolls with poor-quality winding with crane tongs.	1) Correctly set the gap between the rulers. 2) Avoid scalloping of the roll at the front and rear ends of the strip. 3) Rolls with low-quality winding should be stored in one tier.
bullion	Surface defect in the form of tongue-shaped delamination, partially connected with the base metal, formed from the roll of oxidized splashes, splashes and rough surface irregularities of the ingots due to defects in the inner surface of the mold.	1) Rolling out flaws, undercuts, traces of deep cleaning of defects and gross mechanical damage; can also be formed due to the strong development of the rolls.	1) Control over the condition of the rolling reinforcement and guide rails, compliance with the technology of stripping slabs, transshipment of rolls with working out.
fluffed roll	Roll shape defect in the form of a loosely wound strip	1) Winding of cooled strips. 2) Fluffing by reverse when the roll is “nibbled” on the drum.	1) Avoid emergency stops on winders. 2) Adjust the winders correctly.
		Violation of the temperature regime of the winding. Increasing the roll removal time from the tilter Roll fall	1) Observe the temperature regime of the winding. 2) Compliance with the cycle of work of the winders.
Sink	Defect of the strip surface in the form of a single depression formed when a rolled-in foreign particle falls out or is etched out.	1) Delamination from the surface of captivity. 2) Ingress of foreign particles onto the surface of the strip during rolling.	1) Compliance with the technology of smelting and pouring steel, compliance with the technology of stripping slabs. 2) Ensure the operability of all hydraulic blowers behind the finishing group of stands and in front of the winders.
rolled out	Surface defect, which is a metal break formed during the rolling of a longitudinal or transverse crack in a slab, ingot or cast billet	1) Rolling out of a longitudinal or transverse crack in the slab due to a violation of the technology of pouring metal.	1) Rolling is not eliminated. Observe the technology of smelting and pouring steel.
Rolled in metal particles	Sheet surface defect in the form of welded and partially rolled pieces of metal	1) Sticking during rolling of chips or detachment from the torn edges of the strip.	1) Monitor the condition of the wiring fittings and the installation of vertical rolls according to the level of rolling.
Unwound strip	Cold strips not wound into a winder for various reasons	1) Equipment failures of winders, jams on winders	1) Avoid failures and jams.
Shells from fallen captives	Shells of various shapes and sizes on strips	1) Rolling of metal with a “captivity” defect	1) Avoid violations in previous stages.
Light weight	Roll weight inconsistency with order conditions	1) The roll chopped on the intermediate roller table due to the jamming of the strip in the finishing group of stands or in the winder.	1) Avoid getting stuck.
Scratch	Surface defect, which is irregularly shaped and arbitrarily directed depressions, in the form of shiny straight lines or scratches	1) Formed as a result of mechanical damage during storage and handling of rolls by cranes.	1) Follow the roll storage technology.
	Defect in the form of distortion of the round shape of the roll	1) Roll drop 2) Collapse of the roll by other rolls on the conveyor or on the turntable, or during storage	1) Avoid dropping rolls. 2) Control the movement of rolls on the outfeed conveyors and through the turntables.

Between 1.01.09. to 31.12.09 Mill 2000 produced 5,534,998.0 tons, of which 11,606.63 tons were defective products. Data on the number of rejects at mill 2000 are provided in Table 1.5.

Table 1.5 - Information on the results of sorting nonconforming products according to the quality of HPC-10 for 2009

Defect name
torn edge
waviness
inversion of the edge
fluffed roll
crescent
light weight
telescopic roll
narrow, wide

Table 1.6 - Data table for constructing a Pareto chart

Type of defect	Marriage, tons	share of defects in all products, %	the share of marriage for each attribute in the total amount,%	Total share, %
thin, thick, variegated
narrow, wide
telescopic roll
light weight
crescent
fluffed roll
inversion of the edge
waviness
torn edge

Table 1.6 shows the tonnage of defective products. Figure 1.2 shows the Pareto Chart by type of marriage. The Pareto chart is a simple and effective way to highlight the most important problematic issues, it makes it possible to compare many different factors and see their order in order of importance, to show objectively the actual state of affairs in an understandable and visual form.

Figure 1.2 - Pareto chart by type of scrap at Mill 2000 at HPC No. 10

As can be seen from the graph, the greatest attention should be paid to the overestimated type of marriage - narrow, thick, different thickness, because. its percentage is 54.66% of the total number of marriages. Violation of technology causes deviations that lead to the receipt of so-called non-conforming products. The most typical product defects and ways to eliminate them are shown in Table 1.4. An analysis of already existing methods for eliminating defects proved that the quality control system is not perfect. The cause-and-effect diagram of Ishikawa (Fig. 1.3) shows all the factors that affect the quality of the hot-rolled sheet, as well as the level of defects and rejects.

From the cause-and-effect diagram, it follows that the most attention should be paid to such a factor as measuring equipment.

Modernization of measuring equipment will allow more accurate measurements of the bandwidth, which in turn will provide reliable readings and product quality control.

Figure 1.3 - Causal Ishikawa Diagram

2. Modernization of the system for measuring the strip width at the rolling mill with a capacity of 2000 at Rolling Shop No. 10 of OJSC MMK

This chapter considers the possibility of modernizing the system for controlling the thickness and width of the strip at the mill 2000 g/p JSC "MMK" through the introduction of a stereoscopic width gauge. This proposal will increase the reliability of quality control and reduce defects in metal rolling.

The stereoscopic width gauge is the latest technological development for measuring the width of a strip or plate, which is installed above the roller table of rolling mills in hot or cold rolling shops. When used in the rough rolling steps or at the exit from the rough rolling, self-emitting IR hot strip provides contrast for width determination. In places where the temperature of the product is below 600, an additional high-frequency backlight is used.

2.1 Crop optimization system

Surveillance System CV3000 : A high-speed matrix camera is used to capture the image of the beginning and end of the workpiece. The nest recognition software analyzes the image and accurately determines the complete profile of the workpiece. The optimal cutting line is determined by the computer based on the shape of the workpiece and the strategy matrix. By default, all information is exchanged with the host computer using the Ethernet protocol. The system has the ability to conduct complex diagnostics in real time. Various possibilities for roughing and reversing stands.

Control systemSC3000 : The control system ensures that the cut of the passing workpiece will occur exactly along the line of optimal cutting.

This is followed by a sensor that measures the speed of the passing workpiece in front of the shear. Surveillance system transmits trim line information control system(Motion Sensor). The motion sensor calculates the exact shear trigger time based on the speed and position of the passing workpiece, as well as on the basis of the specified shear acceleration characteristics. It then tracks the workpiece and adjusts the shear speed (closed loop control) so that the cutting occurs exactly along the line calculated by the monitoring system.

2.2 Bandwidth measurement

The compact and high-precision stereoscopic width gauge is designed for hot strip and plate rolling mills. This sensor uses stereoscopic geometry and calculates the exact width of the strip, even when it vibrates, rises and tilts relative to the plane of the passage on the rolling mill. The DigiScan XD4000 is ready to connect to the factory network using the Ethernet TCP/IP protocol. The rugged, water-cooled, air-cooled, die-cast aluminum housing allows the meter to operate smoothly in hot strip and plate rolling mills.

Application data - operating and performance characteristics are presented in tables 2.1 and 2.2.

Table 2.1 - Performance characteristics of a stereoscopic meter

Table 2.2 - Operating characteristics

Figure 2.1 - Installation location parameters on the mill

The installation diagram (Fig. 2.1.) is typical. Depending on the conditions in the workshop, it will be specified.

2.3 System description

The system works on a client-server architecture. The meter is a server and provides measurement data. Different workstations (clients) on the network can access data for display, recording and meter settings.

The system communicates with the host computer on the current width, lane number, etc. It also transfers all measured values ​​to the host computer. Data transmission takes place via the TCP/IP protocol via an Ethernet network. The structure of the system is shown in Figure 2.2.

Figure 2.2 - System structure

2.4 Specifications of the stereoscopic meter

Figure 2.3 shows the DigiScan XD4000 stereoscopic measuring head.

Figure 2.3 - DigiScan XD4000 stereoscopic measuring head

Designed to achieve high accuracy and reliability in harsh environments in hot rolling mills:

The DigiScan XD4000 measuring head includes 2 high resolution digital cameras (24096 pixels - 4096 gray gradient resolution);

Advanced edge detection software down to half a pixel;

High-speed processing up to 1000 pictures per second (depends on strip temperature if thermal self-radiation is used);

Diagnostic software to solve problems.

Modular structure:

direct connection of the sensor to the Ethernet TCP/IP network;

The network architecture based on the client-server principle allows you to access simultaneously from several computers, working with different screens of the program;

Communication between programmable controller and host computer.

Easy installation, adjustment and maintenance;

Easy and fast changeover if the sensor needs to be replaced:

Light weight and rugged housing - IP66 standard;

water cooling and air blowing system;

Two cables - 15 pin I/O connector and Ethernet.

Graphical window interface includes:

Serial number of the strip, Nominal specified width;

Deviation from the specified width;

Deviation from the center line;

Average, minimum and maximum bandwidth setting;

Performance ratio (strip length between the lower - upper limit in relation to the total length);

The screen is configured to display current or current plus previous bands or other information;

Possibility to display for comparison any profiles of bands (chronology function).

2.5 Structure of connection to the enterprise network

The DigiScan XD4000 has a very flexible connection structure thanks to the built-in Ethernet TCP/IP connection, serial port and built-in digital and analog I/O, and can be easily integrated into any automation system.

Ethernet TCP/IP will be able to provide a layer 2 connection to a computer for the exchange of band identification and measurement data.

The sensor has a built-in Modbus TCP/IP protocol for information exchange with the host computer.

The system has the following built-in Inputs/Outputs:

Analog Inputs;

analog output;

2 Digital Inputs;

2 digital outputs.

Standard analog input and output: 4-20 mA.

Accuracy: 0.1% of reading and 50 ppm/temperature fluctuation.

All changes for each strip are recorded on the hard disk (in archive files) of one of the workstations for further display, comparison of the analysis of the profile width. Each workstation (workstation) can store over 500,000 spools/sheets.

All occurring events are determined and recorded in a file for the convenience of system diagnostics. Such events are alarms, sheet marks, sensor triggering. For each of these events, the status and temperature of the sensor, the measurement status, etc. are recorded.

2.6 Meter verification

The DigiScan width gauge is supplied with a verification template and calibrated software. The check pattern is used to simulate the measurement product. It consists of a set of LED modules and a certified mask with 10 compartments to simulate 25 different sheet widths.

The calibration template is mounted on the roller table and aligned with the sensor, thanks to the visible laser line coming from the sensor itself. The calibration software automatically measures 25 different mask widths in Calibration mode and displays statistics on all results. At the end of the calibration, the result is saved to a file and printed.

Calibration includes measurements at 4 different template positions:

at the basic level;

at the base level + 200 mm;

inclined (base level on the right and +200 mm on the left);

inclined (+200 mm on the right and base level on the left).

A total of 100 measurements.

2.7 Curvature option

Curvature is the deformation that occurs along the length of the steel plate during the hot rolling process.

The measured value of the 2 end meters is summed up and divided in half. If the measurement object has no curvature, then the value of the central meter will be equal to the average value of the two extreme meters.

Any deviation with a positive or negative value will indicate the curvature of the object.

The width meter gives the bar and centerline position, but since Since this measurement is made only at one point, it does not allow measuring the shape of the strip in the direction of its length (curvature profile).

A standard width gauge cannot tell the difference between the centerline offset and the strip position itself as it travels on the roller table.

To obtain the profile of the curvature of the strip, it is necessary to measure the position of the edges of the strip at least at three points along the length of the strip at a time. In order to accomplish this, DELTA has added a spatial camera that captures a complete picture of the edges in one go.

A profile curvature meter that uses a spatial camera aimed at one of the edges of a strip or sheet in the direction of travel. This arrangement effectively eliminates the effects of sidewalks, turns or other obstructions caused by lane movement.

Interference caused by vertical vibration, buckling, and the like is eliminated by the stereoscopic arrangement of the DigiScan line cameras

XD4000 used to determine the coordinates of the strip edges.

The location of the meter with the curvature option is shown in Figure 2.4.

Main features:

Two digital CCD cameras with a resolution of 4096 pixels each and high-quality multi-lens optics, installed in a special optical frame for stereoscopy;

The spatial camera determines the shape of one edge in a section of about 2.5 m every 30 ms, or 0.6 m if the strip speed is 20 m/s;

Stereoscopic correction of measurements to take into account the vertical movements of the strip above the passage line;

Algorithms for constructing a complete profile of a strip or sheet based on multiple images along the length of rolled products.

List of sources used

1. Hot rolling of strips in a 2000 hot rolling mill. Technological instruction. TI 101-P-GL10-374-90.: - Magnitogorsk, 1999. - S. 7 - 53.

2. Rolled thin-layer carbon steel of high quality and ordinary quality for general purposes. Specifications. GOST 16523 - 97.: - Minsk: Interstate Council for Standardization, Metrology and Certification: Standards Publishing House, 1999. - S. 25 - 46.

3. Hot-rolled quality carbon steel for general purposes. Specifications. STP MMK 325-2004.: - Magnitogorsk, 2003. - S. 14 - 19.

4. Rolling production: a textbook for universities / P.I. Polukhin, N.M. Fedosov, A.A. Korolev Yu.M. Matveev; - Ed. 3rd, perab. and additional - M.: Metallurgy, 1982. - S. 69 - 89.

5. Technology of production of sheet steel / V. M. Salganik, M. I. Rumyantsev. - Magnitogorsk, 2007. - S. 6 - 8.

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SECTION 4. PRODUCTION OF HOT ROLLED STRIPS AND SHEETS

ON BROADBAND HOT ROLLING MILLS

Wide-strip hot rolling mills (SHSHP) include multi-stand mills with the placement of stands in roughing and finishing groups. In the roughing group, both non-reversible and reversible stands are used, located discontinuously or continuously, and in the finishing group, the stands are always located continuously. All products at ShSGP are wound on winders.

Assortment

On ShSGP rolled sheet and strip products with a thickness of 0.8 to 27 mm and a width of up to 2350 mm. The main assortment of mills of this type is strips with a thickness of 1.2-16 mm from ordinary and high-quality carbon, low-alloy, stainless and electrical steel grades.

Consumers

General mechanical engineering, shipbuilding, agricultural engineering, production of welded pipes, rolling stock for CKU.

Types of SHGP

Continuous.

Semi-continuous.

Combined.

3/4-continuous.

The location of the main technological equipment of these mills is shown in Figure 29.

The classic continuous SHSHP is characterized by a discontinuous arrangement of the stands of the roughing group. Moreover, the distance between the stands increases from the first to the last stand in order to ensure the condition of finding the roll in only one stand. This is due to the fact that asynchronous AC motors are used as a drive in the stands of the roughing group without the ability to control the rolling speed. In front of the roughing stands with horizontal rolls, vertical rolls are installed driven by DC motors and with the possibility of matching the rolling speed in them with the rolling speed in the stand with horizontal rolls. The purpose of using stands with vertical rolls is to remove the broadening formed in horizontal rolls and work out the metal of the edges to prevent their rupture.

Fig.29. Location of the main technological equipment of ShSGP of different types: 1 - heating furnaces; 2 - vertical scale breaker; 3 – rough scale breaker duo; 4 - draft group of universal non-reversible quarto stands; 5 - intermediate roller table; 6 - flying scissors; 7 – finishing scale breaker duo; 8 - finishing continuous group of quarto stands; 9 - discharge roller table; 10 - shower installation; 11 - the first group of winders; 12 - the second group of winders; 13 - reversible universal duo or quarto stand; 14 - stand with vertical rolls; 15 - draft stand duo or quarto reversible; 16 - roughing stand quarto reversible; 17 - a rack for transferring thick sheets to the finishing and cutting area; 18 - continuous draft subgroup of non-reversible universal quarto stands

The intermediate roller table must ensure complete placement of the roll coming out of the roughing group of stands, that is, "untie" the roughing and finishing groups of stands, since the speed of the roll exit from the last stand of the roughing group is 2-5 m/s, and the entrance to the first stand of the finishing group - 0.8-1.2 m / s.

This is followed by flying shears, in which the front and rear ends of the roll are cut (if necessary) and an emergency cut is made when “drilling” the strip in the finishing group of stands or on the discharge roller table and winders.

The finishing group of stands is always continuous with a distance between stands of 5.8-6 m. The number of stands is 6-7.

The discharge roller table is equipped with a showering installation.

For winding strips, two groups of winders are usually provided.

The distance between the main units is shown in Fig.29.

Semi-continuous mills have been and are being used for smaller production volumes. One draft reversible stand is provided as a draft stand. On modern mills, it is universal.

The rest of the equipment is similar to the continuous SHSHP, but 6 stands are used in the finishing group, and the winder group is usually one.

Combined mills are characterized by the fact that a two-stand TLS is used as a roughing group, then there is a schlepper for transferring thick sheets to a finishing section, also similar to the TLS.

After the intermediate roller table, a six-stand continuous group of stands is installed.

It is characteristic that the barrel of rolls of roughing stands is larger than that of finishing ones.

The discharge roller table and winders are located as on a semi-continuous SHGP.

Main dignity combined mills - a wide range of products (usually 2-50 mm in thickness, 1000-2500 mm in width).

Basic flaw mills of this type - insufficient loading of equipment, both when rolling thick and thin sheets.

In this regard, the combined mills were no longer built more than 30 years ago, but the built ones are mostly working.

There are two such mills in Russia.

3/4-continuous mills are characterized by the presence of a vertical descaler, a reversible universal stand and a two- or three-stand continuous subgroup. All other equipment is the same as on a continuous SHGP.

The mill scale along the ShSGP production line is cracked in horizontal and vertical scale breakers, and also knocked down in high-pressure hydraulic knockers (primary), secondary - before the finishing group of stands in horizontal scale breakers or hydraulic knockers (see Section 7).

Generations GSGP

It is generally accepted to divide the SHGP into generations. Table 14 presents their characteristics.

The first SHGP began to work in the USA. The characteristic features of the GSGP of the first and second generations were the use

– duo stands as a scale breaker, located immediately after the heating furnaces;

– hydraulic scale removal before rolling in roughing stands;

– discontinuous arrangement of the stands of the roughing group (peel was not rolled simultaneously in two stands);

-universal quarto stands in the roughing group;

- an intermediate roller table with a length greater than the length of the rough roll outgoing from the last stand;

– flying scissors for trimming the ends of the rolls and performing an emergency cut;

–finish scale breaker duo;

– continuous arrangement of quarto stands in the finishing group;

– a sufficiently long roller table after the finishing group of stands;

– winder for winding the strip into a roll.

The first stage of development was the longest. The classic SHGP of the first generation is the still operating mill 1680 of JSC Zaporizhstal, put into operation in 1936. It provided for the rolling of strips with a thickness of 2-6 mm and a width of up to 1500 mm. A feature of the mill 1680 was the presence of an expansion stand and a press in the roughing group. The broadening stand was used for rolling strips when their width was greater than the width of the slab, and the press was used to align the "littered" edges of the rolled product and ensure it had the same width along the length. Compression in the press was 50-150 mm.

Table 1

Characteristics of SHSGP

Generation	Years of construction	Slab dimensions	Mass of slabs, t	Thickness of rolled strips, mm	Barrel length of horizontal rolls, mm	Maximum rolling speed, m/s	Number of stands in a group	Productivity, million tons/year
thickness, mm	length, m	draft	finishing
	until the end of the 50s	105-180	£6.5	6-12	2-12,7	1500-2500*		4-5	5-6	1-2,5
	50-60s	140-300	£12	28-45	1,2-16	2030-2135		5-6	6-7	2-3
	70s	120-355	£15	24-45	0,8-27	2135-2400	30,8**	6-7	7-9	until 6
	80s	140-305	£13.8	24-41	1,2-25,4	1700-2050		3-4	5-7	4-6
	90s	130-260	12,5	25-48	0,8-25					5,4
* Mill 2500 MMK (Russia). ** With 9 stands in the finishing group.

After reconstruction in 1956-1958. at the 1680 mill, rolling with broadening of slabs was no longer used. And the press was stopped operating even earlier due to the low speed of the compression operation and a number of design flaws. The last ShSGP in the world, where an expansion stand was used, was the ShSGP 2500 of the Magnitogorsk Iron and Steel Works OJSC (also the first generation ShSGP), which began operation in 1960. This need was caused by rolling strips with a width of 2350 mm. The 2500 mill is also characterized by the fact that it has the longest roll barrel length in the world (for SHGP). Currently, the 2500 mill uses continuously cast slabs up to 2350 mm wide and the need for an expansion stand is no longer needed.

Since the hydro-scale scales had low water pressure at that time, the furnace scale had to be cracked first. For this purpose, the duo rough scale breaker was designed. It produced very small compression (2-5 mm). With the increase in water pressure in the hydrodescaling, this stand began to be used as a roughing stand with reductions up to 20-30%.

The growing demand for sheet products has led to the creation of the second generation SHGP. The assortment of strips has been expanded both in thickness and width (the length of the roll barrel has been increased), the mass of slabs has significantly increased (up to 45 tons) and the rolling speed has increased up to 21 m/s.

An increase in the weight of the slabs caused an elongation of the rolled strips and, in connection with this, worsened the temperature conditions for their rolling, mainly due to a drop in the temperature of the strip when it entered the first stand of the finishing group at a relatively low rolling speed. And since the limitation of the rolling speed was (and still is) the speed of capturing the front end of the strip by the coiler (no more than 10-12 m/s), then the acceleration of the finishing group of stands was used for the first time at the second-generation SHSHP. It was started immediately after the strip was captured by the winder. It can be considered that this is the main qualitative difference between the second generation SHGP and the first one.

The annual production capacity of the second generation SHGP approached 4 million tons. The number of stands has been increased both in the roughing and finishing groups.

Characteristic of this generation of SHSHP is a further increase in the number of stands, and hence the production line of mills, as well as the expansion of the range of rolled strips in size, including width, which required an increase in the length of the roll barrel up to 2400 mm (see Table 14). ). With a reduction in the maximum mass of slabs, their thickness increased to 300-350 mm.

Another feature of the third-generation SHSHP was the desire to expand the range of rolled strips in terms of thickness, both towards maximum and minimum values. It was on some of these mills that the rolling of strips with a thickness of 1-0.8 mm was started, which was briefly discussed in subsection 1 of this chapter.

Due to the increase in the thickness of slabs up to 355 mm, as well as the realization of the possibility of rolling strips with a thickness of 0.8-1 mm, it was planned to install 8 and 9 stands in the finishing group on a number of third-generation SHGPs, bringing the rolling speed to 30.8 m/s and relative weight of rolls up to 36 t/m strip width.

It turned out that the main reason for this idea was that at that time the capacity of cold rolling mills in Japan was not enough. When such mills appeared in Japan, the rolling of strips with a thickness of less than 1.2 mm was stopped on the SHGP, the 8th and 9th stands in the finishing group were not installed on any SHGP in the world and the rolling speed of up to 30 m/s was not achieved. .

ShSGP of the third generation in the USSR were mills 2000 of OJSC Novolipetsk Metallurgical Plant (NLMK) and OJSC Severstal, put into operation in 1969 and 1974, respectively. The mills provide for the rolling of strips with a thickness of 1.2-16 mm and a width of up to 1850 mm from slabs weighing up to 36 tons and maximum rolling speeds of up to 20-21 m/s.

The difference between them is that the location of the roughing stands at the NLMK mill 2000 is traditional - discontinuous (Fig. 30), while at the Severstal mill 2000 the last three stands are combined into a continuous roughing subgroup (three stands for the first time in the world). Another difference between these mills is that the length of the discharge roller table on NLMK's 2000 mill is 206,700 mm, and on Severstal's 2000 mill, 97,500 mm. The approach of the winders on the mill 2000 of OAO Severstal to the last stand of the finishing group made it possible to reduce the time of rolling the front part of the strips at low speed. Reducing the temperature of winding thick strips is achieved by increasing the distance between the first and second groups of winders. Both mills have a capacity of 6 million tons per year.

Fig.30. The layout of the main equipment of the continuous ShSGP 2000 of OJSC NLMK: 1 - furnace roller table; 2 – trolley for transferring slabs; 3 – slab pushers; 4 - heating methodical furnaces; 5 - receiving roller table; 6 – receiver of heated slabs; 7 - vertical scale breaker (VOK); 8 - two-roll stand; 9 - universal four-roll stands; 10 - intermediate roller table; 11 – flying scissors; 12 - conveyor for the head and bottom trim; 13 – finishing two-roll scale breaker; 14 – finishing four-roll stands; 15 - discharge roller table; 16 - winders for winding thin strips; 17 - conveyors; 18 - lifting and rotary table; 19 - winders for winding thick strips; 20 - roll storage and sheet finishing department

The operating experience of the third generation SHGP has shown that the expansion of the range of rolled strips and the increase in the mass of slabs cause an increase in the mass of equipment, and, consequently, the cost of the mill and shop, lengthening of the technological line of the mill (up to 750 m), expansion of the range of strips in thickness up to 0.8 mm , create difficulties in maintaining the required temperature conditions of rolling, cause inefficient use of the mill equipment (when rolling strips with a thickness of more than 12-16 mm and a width of less than 1500 mm, it is used at about 30% of its capacity). In addition, strips with a thickness of 0.8–1 mm were significantly inferior to cold-rolled strips of the same thickness in terms of rolling accuracy, mechanical properties, surface quality, and presentation.

Due to these shortcomings, as well as the high cost (over 500 million euros) of the third generation SHGP, the fourth generation SHGP appeared.

Their main distinguishing feature was the installation of a universal reversible stand in the roughing group of stands, which increased the crimping capacity and reduced the length of the roughing group of stands.

In addition to the reverse stand, there are four more universal stands in the roughing group, two of which (the last ones) are combined into a continuous roughing subgroup. A number of mills of the fourth generation used intermediate rewinders, which will be discussed later. Representatives of the fourth generation SHGP is the Baostill 2050 mill, the equipment layout of which is shown in Fig. 31.

Mill 2050 began operating in 1989. It is designed for rolling strips 1.2-25.4 mm thick and 600-1900 mm wide. Maximum coil weight 44.5 tons, rolling speed up to 25 m/s, annual production 4 million tons.

A characteristic feature of the mill is the presence in the roughing group of stands of two reversible universal stands (the first is a duo, the second is a quarto) and the combination of the remaining two stands into a continuous subgroup. There are seven quarto stands in the finishing group. Mill 2050 has one group of coilers. In the roughing group of stands, it is possible to reduce and adjust the width of the rolls. Reducing is carried out in the first roughing universal stand, which has a powerful stand with vertical rolls (in three passes it is 150 mm), and the width is adjusted in all other stands of the roughing group by reducing the rolled stock in vertical rolls.

Fig.31. The layout of the main equipment of the 3/4-continuous ShSGP 2050 "Baostill": 1 - furnace roller table; 2 – slab pushers; 3 - heating methodical furnaces with walking beams; 4 – slab dispensing device; 5 - receiving roller table; 6 - two-roll universal reversible stand; 7 - four-roll universal reversible stand; 8 - four-roll universal non-reversible stands combined into a continuous roughing subgroup; 9 - intermediate roller table; 10 - heat-insulating lifting screen; 11 - crank shears; 12 - roller guide wiring; 13 - finishing continuous group of four-roll stands; 14 – discharge roller table; 15 - shower installation; 16 - winders; 17 - adjusting

These mills are called 3/4-continuous SHSHP.

It should be noted that 3/4-continuous mills are currently considered the most modern and efficient.

The desire to use hot-rolled (cheaper) sheet instead of cold-rolled sheet led to the creation of SHSHP, the assortment of which includes strips 0.8-25 mm thick and 600-1850 mm wide (Fig. 32). This became possible due to more advanced automation systems, the use of intermediate rewinders, a press for reducing slabs and removing their taper.

These mills are called "endless rolling mills". They are assigned by us to the fifth generation.

In fact, endless rolling mills are 3/4-continuous, but their difference is the installation of a machine for welding rolls on the intermediate roller table.

The welding machine consists of scissors intended for trimming the ends of the rolls, a system for centering the rolls, clamps for holding the rolls during heating and upsetting, an inductor, a mechanism for compressing the welded ends of the rolls and a deburring device. The full cycle of rolling, positioning, heating and welding of the ends is 20-40 minutes.

The length of the welding section with equipment located on it is 12, the height and width are 6 m each. The cost of the welding section with peripheral equipment is approximately 114 million dollars, and the cost of the mill is more than 1 billion US dollars. Such a huge cost is due to the presence on the mill of almost all possible equipment for SHGP and a complex of automation systems, often duplicating each other. The allowable rolling force in the stands of the roughing and finishing groups is in the range of 38-50 MN.

Fig.32. Layout of the main equipment of the ShSGP 2050 by Kawasaki Steel (Japan):

1 - heating furnaces; 2 – press for width reduction of slabs; 3 – reversible stand duo; 4 - draft stands quarto; 5 - PPU; 6 - scissors; 7 - strip welding area; 8 - section for heating the edges, trimming the ends and churning off the scale; 9 – finishing group of stands; 10 - shower installation; 11 - dividing scissors; 12 - device for pressing the strip to the roller table; 13 - winders

In the endless rolling mode, strips are produced with the dimensions shown in Fig. 33. The mill achieved high accuracy of rolling strips in thickness and width, high flatness. Welding strips (up to 15 pieces) into an “endless” strip allows maintaining a high and constant rolling speed, which causes many positive aspects.

The practice of operating such mills has shown that it is possible to roll strips with a minimum thickness of 0.8 mm with high accuracy, to practically exclude transient modes of entry-exit of the ends of the strips, accompanied by a decrease in the rolling speed followed by rolling of the strips with acceleration, as well as dangerous from the point of view of possible band jams.

However, some issues with endless rolling have not yet been resolved, and it has the following disadvantages:

– the impossibility of rolling in an endless mode for more than 15 strips due to an increase in the temperature of the rolls and a change in their thermal convexity;

- the need to start rolling from strips with a thickness of 2-2.5 mm, and then make a dynamic restructuring of the mill during rolling sequentially to a thickness of 1.5 - 1.2 - 1 - 0.8 mm, which leads to obtaining strips of different thicknesses;

– high cost of the mill (more than 1 billion US dollars, including the welding section – 114 million US dollars).

All three continuous rolling mills are in operation in Japan. In our opinion, this is a dead-end path for the development of the SSHP. The task of obtaining strips with a thickness of less than 1.2 mm can be solved much more easily in casting and rolling units (see below).

Rolling schemes

Earlier it was said that at the first generation SHGP, a preliminary breakdown of the width was envisaged due to the lack of slabs of sufficient width. At present, the possibilities of casting slabs at the continuous casting machine have made it possible to completely solve this problem. Therefore, only longitudinal rolling pattern.

Metal rolling in roughing and finishing groups of stands

The number, type and nature of the location of the stands depend on the type of SHGP. The main changes at the GSGP are related to the roughing group. The common feature is the presence of scale breakers with horizontal or vertical rolls (VOK). Initially they were used to break scale, then they began to be used to adjust the width of slabs.

During the transition of SHGP to continuously cast billets, some difficulties arose in organizing the production of strips of the entire range of widths. On ShSGP, strips are usually rolled with a width of gradation of 20-40 mm. Upon receipt of rolled slabs from slabs or blooming slabs, it was possible to order their rolling with any gradation in width.

On the CCM slabs are cast with a width corresponding to the width of the installed mold. When an enterprise has a lot of continuous casting machines, each of them can be specialized in casting slabs of 3-4 sizes in width. If there are only 2-3 CCMs, then there is a need for frequent replacement of the mold, and consequently, there are losses in productivity, metal, and the quality of slabs deteriorates during periods of non-stationary casting.

This problem is solved in different ways. Firstly, molds with a changing position of the end walls are used directly in the CCM. This method has a number of disadvantages - the complication of the design of the mold, the violation of the casting regime, and, consequently, the loss of production, the deterioration of the quality of the metal, the casting of slabs of variable width.

Secondly, FOC is used both to reduce the width of slabs and to eliminate the wedge shape of slabs.

So, on the Baostill mill 2050 (see Fig. 31), two reversible stands are installed in the roughing group - one duo, the second quarto. Moreover, the duo stand is universal with powerful vertical rolls (electric motor power 3000 kW, roll diameter 1100 mm). The second stand (quarto) is also universal, but less powerful (drive power 2×600 kW, roll diameter 1000 mm). The next two universal quarto stands are located continuously at a distance of 12 m from each other, the drive power of the vertical rolls of each of the stands is 2×380 kW, the diameter of the rolls is 880 mm.

The universal stand duo allows you to reduce the slab by 120 mm in one pass. Moreover, the scheme of slab compression, and then the roll, looks like this: VV-GV-GV-VV-VV-GV. Thus, the sags formed at the edges of the roll are rolled out in horizontal rolls, and then two passes in a row in the vertical rolls of the same stand and again rolling in horizontal rolls follow.

In the case of reverse rolling in the second stand, the scheme of rolling in explosives and hot-waters looks similar. But the possibilities for compressing the roll in width are already much less. In the third and fourth universal stands one pass is made.

The main disadvantages when reducing slabs in vertical rolls

Limitation of the amount of compression according to the conditions of capture, which necessitates a multi-pass process;

The appearance of edge thickenings, which, during subsequent rolling in horizontal rolls, again (by about 60-70%) pass into the width of the roll;

The efficiency of roll reduction in vertical rolls is significantly increased if box gauges are used. But this raises a number of complications:

The need to replace rolls when the thickness of the original slabs changes;

The complexity of cutting calibers on rolls of large diameter;

Increased wear of calibrated rolls compared to smooth rolls;

Increased energy consumption for rolling.

Thirdly, the use of presses. Since the length of slabs on modern SHSHP reaches 15 m, the press performs step-by-step compression of the slab (Fig. 34). During compression by the strikers of the press, the slab is held by rulers, and after each single compression it moves along the process flow line.

A state-of-the-art slab reduction press is installed at the Thyssen Stahl SHG in Beckerwerth.

Technical characteristics of the press

Slab dimensions, mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	700-1200
width. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	700-1200
thickness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	up to 265
length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	3600-10000
Slab temperature, °C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	1050-1280
The total reduction in the width of the slab, mm. . . . . . . . . . . . . . . . .	up to 300
Reduction force, MN. . . . . . . . . . . . . . . . . . . . . . . . . . . . .	up to 30
The length of the compression zone per stroke, mm. . . . . . . . . . . . . . . . . . . . . . . .	up to 400
Frequency of strokes, min -1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	up to 30
Slab movement speed, mm/s. . . . . . . . . . . . . . . . . . . . . . . .	up to 200
Strikers replacement time, min. . . . . . . . . . . . . . . . . . . . . . . . . . . .	to 10

The cycle time of one pass is 2 s. The formation of a thickening on the slab during its processing in the press does not cause any difficulties during further rolling in the roughing reversing stand of the mill. These thickenings are much smaller than when reducing slabs in vertical rolls.

A new technical solution in the draft group was the combination of the last two or three stands into a continuous subgroup. For the first time in the world, three stands were combined into a continuous subgroup at the mill 2000 of OAO Severstal (designer and manufacturer of the mill ZAO NKMZ).

The layout of the stands in this subgroup is shown in Fig.35.

Stand 3 has a roll drive from two DC electric motors with a power of 2x6300 kW (110/240 rpm) through a common gearbox and gear stand. The fourth stand has a similar drive. The fifth stand has a gearless drive from a 2×6300 kW (55/140 rpm) two-arm DC electric motor through a gear stand. The maximum allowable rolling force in stands with horizontal rolls is 33 MN, with vertical rolls 2.6 MN.

The applied drive allows you to adjust the rolling speed in the complex.

The use of a continuous subgroup of stands made it possible to:

– reduce the length of the roughing group of the mill by 50 m, as well as the length of the workshop and roller tables, and, consequently, their cost;

– to improve the temperature regime of rolling by reducing the cooling time of the rolls and increasing the rolling speed to 5 m/s.

Draft stand group should provide

1. The specified roll thickness.

2. A given width of the roll with a minimum variation in width.

3. Required rolling temperature.

The finishing group of stands is always continuous. Some changes have been made to its head section. For a long time, drum shears were used before the finishing stand.

On the new ShSGP, instead of drum shears, crank shears began to be used. Compared to drum shears, thicker rolls can be cut with them, and they have a longer blade life. So, on the Baostill mill 2050, it is possible to cut a roll with a section of 65 × 1900 mm from X70 steel. The maximum cutting force reaches 11 MN, the durability of the knives is 10 times higher than that of drum shears. An optimization system has been installed that ensures minimal loss of metal in trimming.

At the SHGP of the 1st generation, a two-roll stand was used as a finishing scale breaker. Since the reduction in the finishing scale breaker was 0.2-0.4 mm, the stand itself and its drive were low-power, and spring cups were installed between the pressure screws and the pads of the upper rolls. In this case, the pressure on the roll was created by the force of compressed springs and the mass of the upper roll with pillows.

An increase in the mass of slabs, an expansion of the range of SHSHP, an increase in the requirements for the quality of hot-rolled strips (including surface quality) led to the installation of more powerful finishing scale breakers driven by electric motors with a power of 350-400 kW at the SHSHP of the 2nd generation, springs were installed under the pressure screws with force up to 294 kN. The mass of such scale breakers reached 200-300 tons.

The next step was the transition to the use of roller finishing scale breakers, in which the rollers are pressed against the roll with a force of 20-98 kN. For example, in CJSC NKMZ, during the reconstruction of the mill 2000 of OJSC Severstal, a roller scale breaker was designed, manufactured and put into operation.

In the scale breaker of this design, there are two pairs of pressure rollers with a diameter of 500 mm, which, with the help of springs and a lever system, are pressed against the roll and destroy the scale on the roll. This is followed by transport rollers, between which two rows of collectors with hydrodescaling nozzles are installed. Squeeze rollers are installed at the outlet of the scale breaker, which squeeze water from the roll. The mass of the scale breaker does not exceed 50-80 tons.

In the finishing group of stands, four-row bearings with tapered rollers for work rolls and fluid friction bearings for back-up rolls are used.

Since the beginning of the 70s of the last century, the use of hydraulic pressure (with the preservation of electromechanical pressure) devices began in the finishing group of stands.

At the beginning of the 1980s, for the first time in the world, in Japan, six-roll stands of a special design, with the possibility of axial displacement of the work and intermediate rolls, began to be used for hot strip rolling. However, they were mainly used in Japan. They have not received wide distribution.

Finishing group of stands should provide

1. Specified strip dimensions.

2. The specified metal quality in terms of accuracy, including flatness, surface quality and mechanical properties.

At the final stage of development, one of the largest projects of LLC "Corporate Systems" is now - a multimedia training system for training specialists at control stations PU7 and PU9 of a wide-strip hot rolling mill 2000.
Continuous wide strip hot rolling mill 2000 is designed for the production of hot-rolled strips from carbon and low-alloy steel grades. Comprises:
- area for supplying slabs to furnaces and loading slabs;
- draft group of equipment (PU7);
- sections of intermediate roller table and flying shears (PU9);
- finishing group of equipment (PU9);
- cleaning equipment group.
The project being developed by Corporate Systems LLC covers 5 jobs:
- operator of the draft group of equipment;
- roller of the roughing group of equipment;
- operator of intermediate roller table and flying shears;
- finishing group operator;
- finishing group roller.
Each workplace has its own specific features and is designed to perform certain tasks. For example, the main goal of the roughing group is to obtain the output parameters (width, thickness, temperature) of the strip of the required quality behind the sixth stand.

The system completely imitates all the screens and control panels used by specialists, thereby allowing you to study the work, as well as the main actions performed with their help. To do this, the system is equipped with many scenarios with different types of tasks:
 test questions (invite users to choose one answer from several proposed ones);
 questions for self-response (involving self-entry of answers by users);
 pointing type questions (indicate the necessary elements on the screens or control panels);
 performance of an operation (assume that users perform the required operations).
The system provides two modes of passing scenarios:
 demonstration (used for training and is characterized by the presence of various prompts (designed to consolidate the theoretical material by the user), as well as indication (highlighting the elements that are necessary to complete the task));
 testing mode (used directly to test the user's knowledge).

To ensure that the training is as close as possible to the real operation of the mill, the program provides 3D animation, which allows users to see the results of all the actions they perform in scenarios directly on the mill model: equipment status (for example, control of pressure screws, encopanels, flying shears, roller table sections), operating speed, possible accidents (e.g. jamming of slabs, bending of the strip), etc.

The system also implements various simulation models:
 deformation mode model;
 speed mode model;
 temperature regime model;
 tension model;
 loading model of the main drives, etc.
They allow you to imagine the process of rolling metal as it is in reality.
The most important component of the system is a three-dimensional model of the mill, which allows specialists to study in detail the design of the equipment of the roughing and finishing groups, as well as the sections of the intermediate roller table and flying shears.
The design considers not only the structure of equipment groups, but also individual elements (for example, the detailed structure of stands). Convenient navigation, detailed descriptions of the properties and technical characteristics of the elements, as well as the ability to customize the user interface make the learning process as easy as possible.
Also, the design is supplemented with various video materials dedicated to the operation of the equipment (flying shears, industrial roller, finishing group, etc.), and animation videos demonstrating the technology in detail (the operation of loop holders, rolling technology).

In addition, the system is equipped with a variety of reports that allow you to obtain information about the rolling (rolling plan).
The ability to view test results allows you not only to receive information about the correctness of the tasks performed and the time spent, but also to track the operations that the user performed during the scenarios.

Reproduction of user actions in the recording makes it possible to visually follow the testing process later.

Thus, the combined use of computer graphics, animation, "live" video and other media components will provide a unique opportunity to make the studied material as visual as possible, and therefore understandable and memorable. This is especially true for mill 2000 specialists, who have to absorb a large amount of emotionally neutral information - for example, production instructions, technological maps, regulatory documents. Convenient interface and navigation, detailed user and technological instructions make working with the system as simple as possible.

It has been 30 years since the Polish specialists began to build the hot-rolling mill "2000" in the sheet-rolling shop No. 10 of OJSC MMK. The history of this technological complex is rather unusual.

In the mid-70s of the last century, equipment for the 2000 hot-rolling broadband mill was manufactured in the Soviet Union and shipped to the Polish People's Republic. It was planned to include it in the complex of the metallurgical plant in the city of Katowice. But due to the political crisis in the republic, construction was stopped. And on July 25, 1985, a resolution of the Council of Ministers was issued on the re-export of the equipment of the 2000 hot rolling mill for the Magnitogorsk Iron and Steel Works.

In March 1986, by order of MMK director Ivan Romazan, slag removal from the construction site of the 2000 mill was organized. In 1987, the first Polish builders arrived in Magnitogorsk. They were experienced specialists who built many important objects in their homeland. In Magnitogorsk, first of all, they began to build residential buildings, social and technical facilities for Polish workers. The newspaper "Magnitogorsk worker" for September 1987 reports: "... Polish builders plan to build 40 thousand square meters of total living space in the city. In addition to residential buildings, a canteen, a clinic, two clubs, shops, and a consumer service center will soon appear here."

Meanwhile, Polish workers continued to arrive for the construction of the 2000 mill. In 1988, equipment began to arrive from Poland. The builders were interested in delivering all structural elements on time. Within a month, almost four hundred wagons from Poland were unloaded with structures, equipment, building materials, everything necessary for living and working.

In 1989, the installation of the first overhead cranes began in the department for receiving cast slabs. The following year, the installation of heating furnace No. 1 and equipment for the furnace section began. Already in August 1990, Ivan Romazan issued an order to recruit a group of skilled workers - technologists from working rolling shops for training at the 2000 hot rolling mill of the Cherepovets Metallurgical Plant.

The economic crisis of 1992 affected the financing and supply of construction with everything necessary. Difficulties arose with the preparation of rolls for the mill. Senior foreman Yuri Nosenko recalls: "The roll grinding department was not ready. Fluid friction bearings, roll pads - everything was mothballed."

By 1994 the situation had normalized. So, on October 8, at 11:50 am, the first hot-rolled coil with dimensions of 7x1100 millimeters was rolled at the "2000" mill. This date is considered the birthday of sheet-rolling shop No. 10. And the hot-rolling mill "2000" became the first large industrial facility at MMK, built with the help of foreign builders and specialists.

In the mid-2000s, the unit was reconstructed. As part of the modernization, the fourth heating furnace was built, the mechanical equipment of the mill was updated, which made it possible to produce a thicker assortment. In addition, new technologies were introduced that made it possible to switch to a fully automated mill control mode.

In 2016, more than five million tons of hot-rolled products were produced at the 2000 hot rolling mill. This is the highest figure for the entire period of operation of the mill.

Today the hot rolling mill "2000" is one of the most powerful and modern in Russia. The equipment makes it possible to roll all currently existing steel grades. The range of products manufactured here is very wide. The range of applications is also diverse - pipe production, construction industry, mechanical engineering. Marine and structural steel grades, transformer steel are rolled here.

Mill "2000" can safely be called a symbol of Soviet-Polish friendship, which sealed international ties with the Polish Republic.

Olga Ryzhkina, chief archivist of the city archive.