The production facilities of Zaporizhstal are:

· Sintering shop (6 sintering machines);

· Blast furnace shop (4 blast furnaces);

· Workshop for preparation of trains;

· Foundry;

· Crimping shop;

· Workshop for hot rolling of a thin sheet;

Workshop cold rolling № 1;

· Cold rolling shop No. 3.

Figure 1 Production structure of PJSC "Zaporizhstal"

The main iron ore sinter is produced in the sinter shop of the plant. Almost all sinter production processes are automated.

Blast-furnace production annually smelts about 3.5 million tons of pig iron / year. A distinctive feature of the cast iron produced by MK "Zaporizhstal" is its low content of sulfur and phosphorus.

The production of the open-hearth shop is about 4.0 million tons of steel / year. Open-hearth furnaces use natural gas. The steel is purged with oxygen and argon. Smelted steel is poured into ingots weighing up to 18.6 tons, which are used for the production of sheet metal.

The foundry is the base for obtaining cast blanks of spare parts and replaceable metallurgical equipment for the workshops of the plant and third-party consumers, which includes a specialized department for the production of molds. The design capacity of the molds section is 360 thousand tons / year.

Hot-rolled thin sheet shop produces hot-rolled steel in sheets and coils with a thickness of 2.0 to 8.0 mm. The thin sheet hot rolling shop is equipped with units to ensure the supply of rolled products in sheets and coils. Continuous sheet mill "1680" with a maximum production capacity of 3.7 million tons per year is intended for the production of hot-rolled strips with a thickness of 2.0-8.0 mm, a width of 860-1500 mm, a coil weight of up to 16 tons. 500 standard sizes of cold-formed profiles from carbon and low-alloy steel grades with a thickness of 1.0 to 8.0 mm and with a profile sweep width of up to 1440 mm.

Cold rolling shop No.1 produces cold-rolled flat products with a thickness of 0.5 to 2.0 mm, a width of 850 to 1500 mm in sheets up to 4000 mm long and in coils weighing up to 16 tons, as well as cold-rolled strip with a thickness of 0.2 to 2.0 mm.

Cold-rolled rolled products from carbon and low-alloy steel. The workshop is equipped with means for skin conditioning, cross-cutting and longitudinal dissolution, which ensure the supply of cold-rolled steel with a thickness of 0.2 to 2.0 mm, a width of 10 to 1500 mm and a sheet length of up to 3950 mm, as well as coils weighing up to 15 tons.

Cold rolling shop No. 3 at the 2800 mill produces cold-rolled sheets with a thickness of 1.5 to 5.0 mm, a width of 1000-2300 mm and a length of up to 3500 mm from carbon steel grades. The shop has a specialized department for the production of ground and polished sheets and rolls. The maximum production capacity for hot-rolled products is up to 3.7 million tons, for cold-rolled products - 1.1 million tons, for cold-rolled sections - up to 500 thousand tons.

The main activity of the Group is the production of iron, steel and consumer goods at the plant, as well as the sale of these products in Ukraine and abroad. The main consumers of the Group's products in Ukraine are enterprises in the automotive, machine-building industries, agricultural and transport machine-building, as well as the pipe industry.

The high quality of the company's products is confirmed by the demand for it in the domestic and foreign markets. It is in demand in more than 50 countries of the world (Turkey, Italy, Poland, Russia, Syria, Israel, Bulgaria, Ethiopia, Nigeria and others), and the Ukrainian market remains the strategic direction of the plant's sales policy.

The plant maintains a stable position in the market, moving up the list of the largest steel producers year after year. The main efforts of Zaporizhstal specialists are aimed at developing new markets and types of products, strengthening positive image enterprises expanding the geography of supplies. The basis for success is strict adherence and continuous improvement of technological processes, high quality of products, strict fulfillment of contractual obligations, focus on market needs and skillful implementation of market management mechanisms.

SECTION 4. PRODUCTION OF HOT-ROLLED STRIPES AND SHEETS

ON BROADBAND HOT ROLLING MILLS

Wide-strip hot rolling mills (SHSGP) include multi-stand mills with 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 the ShSGP are wound on coilers.

Assortment

Sheet and strip products with a thickness of 0.8 to 27 mm and a width of up to 2350 mm are rolled at ShSGP. 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 machine building, shipbuilding, agricultural machine building, production of welded pipes, tackle for centralized chemical production.

Types of ShSGP

Continuous.

Semi-continuous.

Combined.

3/4 continuous.

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

The classic continuous ShSGP is characterized by a discontinuous arrangement of roughing stands. Moreover, the distance between the stands increases from the first to the last stand, in order to ensure the condition of the roll in only one stand. This is due to the fact that asynchronous AC motors are used as a drive in the roughing stands without the possibility of controlling 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 to work out the metal of the edges to prevent them from breaking.

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

The intermediate roller table must ensure full placement of the rolling stock leaving the roughing group of stands, that is, to "untie" the roughing and finishing groups of stands, since the speed of rolling out of the last stand of the roughing group is 2-5 m / s, and the entry into the first stand of the finishing group - 0.8-1.2 m / s.

This is followed by flying shears, in which they cut off the front and rear ends of the rolling stock (if necessary) and make an emergency cut when the strip is “drilled” in the finishing group of stands or on the discharge roller table and coilers.

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 conveyor is equipped with a sprinkler unit.

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

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

Semi-continuous mills have been and are being used at lower production volumes. One roughing reversing stand is provided as a roughing stand. On the modern countries it is universal.

The rest of the equipment is similar to the continuous ShSGP, but in the finishing group 6 stands are used, and the group of coilers 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 the finishing area, which is also similar to TLS.

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

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

The discharge roller conveyor and coilers are located as on a semi-continuous ShSGP.

The 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 construction of combined mills has ceased to be built more than 30 years ago, but the built ones are mostly working.

There are two such camps in Russia.

3/4 continuous mills are characterized by a vertical scale breaker, a reversible universal stand and a two- or three-stand continuous subset. All the rest of the equipment is like a continuous ShSGP.

Scale along the ShSGP technological line is broken up in horizontal and vertical scale breakers, and also knocked down in high pressure water breakers (primary), secondary - in front of the finishing group of stands in horizontal scale breakers or in water breakers (see Section 7).

Generation ShSGP

The division of the ShSGP into generations is generally accepted. Table 14 shows their characteristics.

The first ShSGP started working in the USA. The characteristic features of the first and second generation ShSGP were the use of

- duo cage as a scale breaker, located immediately behind the heating furnaces;

- descaling before rolling in roughing stands;

- continuous arrangement of roughing stands (rolling was not rolled simultaneously in two stands);

–Universal quarto stands in the roughing group;

–Intermediate roller table with a length greater than the length of the roughing section of the roll coming out of the last stand;

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

- clean descaling duo;

- continuous arrangement of quarto stands in the finishing group;

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

- winders for winding strip into rolls.

The first stage of development was the longest. The classic ShSGP of the first generation is the still operating mill 1680 of JSC Zaporizhstal, which was put into operation in 1936. It provided for rolling strips 2-6 mm thick and up to 1500 mm wide. A special feature of the 1680 mill was the presence of an expansion stand and a press in the roughing group. The widening stand was used when rolling the strips when their width was greater than the slab width, and the press was used to level the rolled edges of the rolled strip and provide it with the same width along the length. The compression in the press was 50-150 mm.

Table 1

Characteristics of ShSGP

Generation	Years of construction	Slab dimensions	Slab weight, 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	rough	fine
	until the end of the 50s	105-180	£ 6.5	6-12	2-12,7	1500-2500*		4-5	5-6	1-2,5
	50-60th	140-300	£ 12	28-45	1,2-16	2030-2135		5-6	6-7	2-3
	70th	120-355	£ 15	24-45	0,8-27	2135-2400	30,8**	6-7	7-9	until 6
	80th	140-305	£ 13.8	24-41	1,2-25,4	1700-2050		3-4	5-7	4-6
	90th	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. rolling with widening of slabs ceased to be used at the 1680 mill. And the press ceased to operate 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 ShSGP 2500 OJSC Magnitogorsk Iron and Steel Works (also ShSGP of the first generation), which began operating in 1960. This need was caused by rolling strips with a width of 2350 mm. Mill 2500 is also characterized by the fact that it has the longest barrel length of rolls in the world (for ShSGP). Currently, the 2500 mill uses continuously cast slabs up to 2350 mm wide and the need for a widening stand has disappeared.

Since the water descaling at that time had a low water pressure, the furnace scale had to be cracked first. For this purpose, the duo roughing descaler was designed. It produced very small reductions (2-5 mm). As the water pressure in descaling increased, 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 ShSGP. The assortment of strips has been expanded both in thickness and in 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.

The increase in the mass of the slabs caused the elongation of the rolled strips and, in this regard, worsened the temperature conditions for their rolling, mainly due to the drop in the temperature of the strip when it enters the first stand of the finishing group at a relatively low rolling speed. And since the limitation of the rolling speed was (and is now) the speed of gripping 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 on the second generation ShSGP. It was started immediately after the strip was captured by the coiler. It can be considered that this is the main qualitative difference between the second generation ShSGP and the first.

The annual productivity of the second generation ShSGP is close to 4 million tons. The number of stands has been increased both in the roughing and finishing groups.

A further increase in the number of stands and, consequently, the technological line of mills, as well as an 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), is characteristic of this generation of ShSGP. ). With a reduction in the maximum mass of slabs, their thickness increased to 300-350 mm.

Another feature of the third generation ShSGP was the desire to expand the range of rolled strips in thickness both towards maximum and towards 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 mentioned in subsection 1 of this chapter.

Due to the increase in the thickness of the slabs to 355 mm, as well as the implementation of the possibility of rolling strips with a thickness of 0.8-1 mm, on a number of third-generation SHSGPs it was planned to install 8 and 9 stands in the finishing group, bring 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 at the ShSGP was stopped, at no ShSGP in the world the 8th and 9th stands in the finishing group were installed and the rolling speed up to 30 m / s was not achieved ...

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

The difference between them is that the arrangement of roughing stands at NLMK's 2000 mill is traditional - discontinuous (Fig. 30), and at Severstal's 2000 mill, 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 take-off roller table at NLMK 2000 is 206700 mm, and at 2000 at Severstal, it is 97,500 mm. The approach of the coilers on the 2000 mill of JSC Severstal to the last stand of the finishing group made it possible to reduce the rolling time of the front part of the strips at low speed. A decrease in the coiling temperature of thick strips is achieved by increasing the distance between the first and second groups of coilers. Both mills have a capacity of 6 million tons per year.

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

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

In connection with these shortcomings, as well as the high cost (over 500 million euros) of the third generation SSGP, the fourth generation SSGP appeared.

Their main distinguishing feature was the installation of a universal reversing 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 reversing stand, the roughing group has four more universal stands, two of which (the last) are combined into a continuous roughing subgroup. On a number of mills of the fourth generation, intermediate rewinding devices are used, which will be discussed below. Representatives of the fourth generation ShSGP are the Baostill 2050 mill, the layout of the equipment of which is shown in Fig. 31.

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

Characteristic feature mill is the presence in the roughing group of stands of two reversible universal stands (the first - duo, the second - quarto) and the union 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, there is the possibility of reducing and regulating the width of the rolls. The reduction is carried out in the first universal roughing stand, which has a powerful stand with vertical rolls (in three passes it is 150 mm), and the width adjustment in all other roughing stands is carried out by reducing the rolled stock in vertical rolls.

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

These mills were named 3/4-continuous ShSGP.

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 the ShSGP, the assortment of which includes strips with a thickness of 0.8-25 mm and a width of 600-1850 mm (Fig. 32). This became possible due to more advanced automation systems, the use of intermediate rewinding devices, a press for reducing slabs and removing their taper.

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

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

The welding machine consists of scissors 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 ends of the rolls to be welded and a deburrer. The complete cycle of rolling, positioning, heating and welding of ends is 20-40 minutes.

The length of the welding section with the 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, and the cost of the mill is more than $ 1 billion. Such an enormous cost is due to the presence on the mill of practically all equipment possible for the ShSGP and a set of automation systems, which often duplicate each other. The permissible rolling force in roughing and finishing stands is in the range of 38-50 MN.

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

1 - heating furnaces; 2 - press for slab width reduction; 3 - reversible duo stand; 4 - quarto roughing stands; 5 - PPU; 6 - scissors; 7 - strip welding area; 8 - section for heating the edges, trimming the ends and knocking down 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 has achieved high precision 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 has 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, practically exclude transient modes of entry-exit of strip ends, accompanied by a decrease in the rolling speed followed by rolling of strips with acceleration, as well as dangerous from the point of view of possible jammed strips.

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

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

- the need to start rolling with 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 the production of 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 endless rolling mills in operation are operating in Japan. In our opinion, this is a dead-end path for the development of the SSGP. The problem of obtaining strips with a thickness of less than 1.2 mm can be solved much easier in casting and rolling units (see below).

Rolling schemes

Earlier it was said that the first generation of the ShSGP provided for a preliminary breakdown of the width 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.

Rolling metal in the roughing and finishing groups of stands

The number, type and nature of the arrangement of stands depend on the type of ShSGP. The main changes at the ShSGP are related to the draft group. The common thing is the presence of a scale breaker with horizontal or vertical rolls (WOK). Initially they were used to break up the scale, then they began to be used to adjust the width of the slabs.

During the transition of the ShSGP to a continuously cast billet, some difficulties arose in organizing the production of strips of the entire spectrum of widths. ShSGP usually rolls strips with a gradation of 20-40 mm. When receiving rolled slabs from slabs or blooming slabs, it was possible to order rolling them with any gradation in width.

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

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

Secondly, WOK is used both for reducing slabs in width and for eliminating wedge-like slabs.

For example, on mill 2050 of the Baostill company (see Fig. 31), two reversing 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 2x380 kW, the diameter of the rolls is 880 mm.

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

In the case of reverse rolling in the second stand, the scheme of rolling in HV and HS looks similar. But the possibilities for squeezing the roll in width are already much less. In the third and fourth universal stands, one pass is performed.

Main disadvantages when reducing slabs in vertical rolls

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

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

The efficiency of rolling stock reduction in vertical rolls is significantly increased if box gauges are used. But at the same time, a number of complications arise:

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

Difficulty cutting grooves on large rolls;

Increased wear of grooved rolls compared to smooth rolls;

Energy consumption for rolling is increasing.

Third, the use of presses. Since on modern ShSGP the length of the slabs reaches 15 m, a step-by-step reduction of the slab is performed in the press (Fig. 34). During compression by the press strikers, the slab is held with rulers, and after each single reduction, it moves along the process flow line.

A modern press for slab reduction is installed at the Thyssen Stahl ShSGP in Bekkerwert.

Technical characteristics of the press

Slab dimensions, mm. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	700-1200
width. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	700-1200
thickness. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 265
length. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	3600-10000
Slab temperature, ° С. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	1050-1280
Overall reduction in slab width, mm. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 300
Reduction force, MN. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 30
The length of the compression zone per stroke, mm. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 400
Stroke frequency, min -1. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 30
Slab speed, mm / s. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	up to 200
Time to replace strikers, min. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...	to 10

The cycle time of one pass is 2 s. The formation of 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 significantly less than in the case of slab reduction in vertical rolls.

A new technical solution in the roughing group was the unification 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 2000 mill at Severstal (the mill was designed and manufactured by NKMZ ZAO).

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

Stand 3 has a drive of the rolls from two DC electric motors with a power of 2 × 6300 kW (110/240 rpm) through a common gearbox and a gear stand. The fourth stand has a similar drive. The fifth stand has a gearless drive from a two-armature DC electric motor with a power of 2 × 6300 kW (55/140 rpm) 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 makes it possible to regulate the rolling speed in the complex.

The use of a continuous subgroup of stands allowed:

- to reduce the length of the roughing mill group 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 up to 5 m / s.

Roughing group of stands should provide

1. The specified thickness of the roll.

2. The specified width of the tackle with the minimum variance.

3. The required temperature of the roll.

The finishing group of stands is always continuous. Its head section has undergone some changes. For a long time, drum shears were used in front of the finishing stand.

On the new ShSGP, instead of drum shears, they began to use crank shears. Compared to drum shears, they can cut thicker rolls, they have a longer knife life. So, on the mill 2050 of the "Baostill" company it is possible to cut a tackle with a cross section of 65´1900 mm from steel grade X70. The maximum cutting force reaches 11 MN, the durability of the knives is 10 times higher than that of the drum shears. An optimization system has been installed to ensure minimal scrap metal losses.

At the 1st generation ShSGP, a two-roll stand was used as a finishing scale breaker. Since the reduction in the finishing mill 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 chocks 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 ShSGP, an increase in requirements for the quality of hot-rolled strips (including the quality of the surface) led to the installation of more powerful finishing scale breakers at the ShSGP of the 2nd generation, driven by electric motors with a power of 350-400 kW, springs were installed under the pressure screws with a force up to 294 kN. The mass of such scale breakers reached 200-300 tons.

The next stage 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. Thus, during the reconstruction of the mill 2000 of JSC "Severstal", at CJSC NKMZ, a roller scale breaker was designed, manufactured and put into operation.

In a scaler of this design, there are two pairs of pressure rollers with a diameter of 500 mm, which, using 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 are installed two rows of collectors with water descaling nozzles. At the outlet of the descaler, squeeze rollers are installed, 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 are used for the work rolls and bearings for liquid friction (WF) of the back-up rolls.

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

In the early 1980s, for the first time in the world in Japan, six-high stands of a special design were used for hot strip rolling, with the possibility of axial displacement of the work and intermediate rolls. However, they were mainly used in Japan. They did not receive wide distribution.

Finishing group of stands should provide

1. The specified dimensions of the strip.

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

In the first five-year plan, in addition to 20 metallurgical plants left over from tsarist times and subject to modernization, for the production of the most important product of industrialization - steel - it was planned to build three more metallurgical giants from scratch - in Magnitogorsk, Kuznetsk and Zaporozhye

Hard thin steel sheet "Zaporizhstal"

In the first five-year plan, in addition to 20 metallurgical plants left over from tsarist times and subject to modernization, for the production of the most important product of industrialization - steel - it was planned to build three more metallurgical giants from scratch - in Magnitogorsk, Kuznetsk and Zaporozhye.

To coordinate the construction of new and modernization of existing plants in 1926 was created Gipromez- State Institute for the Design of Metallurgical Plants. From 1927 to 1932 between Gipromez and an American company Freyn Engineering Company of Chicago a technical assistance agreement was in effect. A group of American engineers and metallurgists, according to the contract, was obliged to conduct training the latest standards American metallurgy Soviet engineers, managers, designers and operators of metallurgical equipment.

In addition to the routine training of specialists, according to the president of the company, Henry Frain, the main task American experts was the general planning of the distribution of capacities and the rational distribution of the entire future metallurgical industry of the Soviet Union.

According to the memoirs of one of the American engineers, V.S. Orr:

« At first we (the Americans), having appeared in Gipromez, only asked questions. All drawings, reports were made by Russians, all decisions were made by Russians. Six months later, we created drawings, nine months later, we were chief designers of metallurgical plants, and at the end of the first year of our work, some of us became heads of departments. The last year of our work, one of us became the assistant to the chief engineer of the entire office. We brought efficiency into the work, removed unnecessary operations and made Gipromez the most effective organization in the entire Union. "

One of the three giants of the first five-year plan, the Kuznetsk Metallurgical Combine was built under the direct supervision of a group of engineers from Freyn Engineering Company... The contract between Freyn and Novostal for the construction of a KMK with a capacity of 1 million tons per year was signed on June 4, 1930. Under the contract, more than 50 American specialists provided design, construction supervision, installation and commissioning of the KMK.

Perhaps the greatest value for the USSR among all imported technologies was the acquisition of the latest American technology for continuous (roll) production of thin steel sheets.

The problem of obtaining wide sheet metal strips in rolls was solved relatively recently - in 1924. Previously, individual attempts were recorded, but due to imperfect technology, they ended in failure. Several factors interfered.

First, it was difficult to precisely control the rotation speed of individual mill stands by the common steam drive, which was used everywhere in metallurgy.

Secondly, only rolling bearings made it possible to switch to high rolling speeds and high loads required for the continuous production of steel sheets.

There was also the problem of bending the long rolls of the twin-roll stand, resulting in uneven sheet thickness.

However, with the release of technologies to a certain stage, it became possible to produce high-quality thin steel sheets.

A three-roll stand appeared, the design of which resisted roll bending much better. The rolls themselves had surface curvature (concave and convex). Each stand was driven by its own electric motor with a variable number of revolutions.

For the first time rolling of this type was mastered by the company " American Rolling Mill Co"In Ashland in 1924. The mill could produce a continuous sheet with a thickness of 0.9 and a width of 1040 millimeters.

The mills of the following design, which have been widely commissioned throughout America since 1926, have already used four-high stands and roller bearings. High speeds made it possible not to install additional furnaces in the gaps between equipment.

The production of a thin steel sheet on an industrial scale made it possible to make a huge technological leap in the production of cars, aircraft, military equipment due to the simplification and simultaneous strengthening of the structure of the designed part, made from one solid sheet.

As of 1937, 21 continuous steel sheet rolling mills were operating in America, while in Europe such mills were just being built - one in Germany by the company Vereinigte stahlwerke, one - in England by a company Richard Thomas.

During the construction of Zaporizhstal in February 1935, the Soviet Union concluded with an American company United Engineering and Foundry Co contract for the development and supply of hot and cold rolling mills. According to the agreement, $ 3 million was paid for equipment, $ 1 million - for technical assistance. We agreed that about 20% of the equipment is supplied from the States, the rest is done in the USSR under the control of the Americans. The company guaranteed technical assistance in starting up and mastering the production, and also undertook to ensure the specified productivity and proper quality of steel sheets.

An interesting point: according to the agreement, each American specialist for the period of his stay in the USSR had to be provided with a separate apartment with a bathroom.

Simultaneously with this agreement, another was concluded - with the company American Standard Corporation for the supply of equipment for rolling mills for $ 3 million.

From the official site of NKMZ (Novokramatorsk Machine-Building Plant):

“In 1934, Europe did not have such complex rolling equipment as continuous broad-strip mills. The Soviet government decided to build a continuous mill at the Zaporizhstal plant, and for this purchase a mill project and some of the most sophisticated equipment in the United States. A commission was organized from representatives of the Zaporizhstal plant, NKMZ, Gipromez, Stalproekt, Electrosila and KHPKU plant, Kharkov design and engineering department of electric drives. [...] The commission left in December 1934, first to Germany, and from there a month later to the USA.

After the completion of the installation, the company undertook to hand over the equipment to Zaporizhstal on the fly, bringing the design capacity of the hot rolling mill to 100 tons per hour or 600 thousand tons per year of sheet with a thickness of 1.5 to 6 mm. It was a colossal performance at the time.

Two inspectors from United Corporation went to NKMZ, and a group of consultants at the time of installation to Zaporizhstal.

Technologists and production workers of the USSR brilliantly coped with the manufacture of complex and precise equipment for the mill. To help NKMZ, Uralmash was allocated, which manufactured tempering stands; SKMZ created adjuster: flying shears, straightening machines, guillotine shears; The Izhora plant supplied various individual machines. The bulk of the equipment for hot and cold rolling mills was manufactured at NKMZ.

In February 1937, hot rolling mill 1680 was started up and showed the high quality of equipment manufactured by Soviet factories, which was not inferior to those purchased in the USA.

Under the contract, during the design of the mill, Zaporizhstal and NKMZ had the right to send up to five specialists to practice at the same time for a period of up to six months. This clause of the contract was used. NKMZ engineers M.Z. Saburov, V.N. Yakovlev, A.M. Kolesker gained experience in the shops of seven factories of the company, the rolling stock of Zaporizhstal - at the metallurgical plant. "

They treated our engineers in America, in their words, with coolness, frivolously. They were not allowed to take notes or take pictures. It was allowed to watch from afar. One of the Cossacks, curious, went behind the fence and thus activated the protective device. The siren began to sound. The entire Soviet delegation was expelled from the shop.

Trainees - metallurgists complained about the condescending attitude of the Americans. They said: - Oh, why do you need to study, why build? It's troublesome. Such a camp is not a Russian cart, but a complex and delicate mechanism. All the same, nothing will come of this venture. Wouldn't it be better to get a finished sheet from America?

Future Chief Engineer Zaporizhstal Yudovich recalled this conversation with an American technologist:

« “Okay,” said the American, “you get the calibration data. If you were from England or Germany, you would never do it.

- Why? - Yudovich was surprised.

- The British or the Germans would have used it right away. But since you are from Russia, it is safe. You will not be able to use it anyway, you will not be able to do it.»

T.V. Jenkins, chief engineer of United Engineering in the USSR, spoke about the problems of installing rolling mills in Zaporozhye :

"One of critical issues discovered in the course of cooperation with Russian mechanics and workers, there was their stubborn ignorance or misunderstanding of the requirements for an exact fit of mating surfaces when installing equipment. They refused to follow the tolerances indicated in the drawings. This is one of the reasons why, in December 1937, the very quickly assembled equipment could not pass acceptance tests. "

For the sake of justice, the opinion of the Soviet side should also be cited. A.V. Miloserdov, the operator of the widening stand of the thin-sheet mill, and the start-up participant, recalled:

- The roughing and finishing stands were set up differently. In finishing - the shaft was planted using a special device, rough ones - by caliber. They were suggested by our mechanic I. Z. Shlykov. But American consultants refused calibers and ... they adjusted the fourth stand using the shaft-to-shaft method until the lower backup roll was broken.

From the memoirs of the former deputy chief mechanic of NKMZ S.3.Milochkin:

“... overseas specialists refused to make drawings in the European version. This created additional difficulties for our designers ... Who among the older generation of Kramatorsk machine builders does not remember the drawings with the warning inscription: "Attention, American projection!"

Although on the official website of NKMZ, in the "history" section, the exact opposite is said:

After signing a contract with United Corporation, American designers specified materials, rolling bearings, fasteners and other components according to Soviet standards.

On April 14, 1938, the first strip was rolled at mill 1680. The senior rolling maker Pyotr Tarasevich, having rolled the first sheet, immediately drew on the steel belt: “ Long live the first Soviet sheet! Helm the curse of the imported sheet!"They say that the American consultant Mr. Faisner took offense and went to complain about Tarasevich to the party organizer ... (By the way, PD Tarasevich retired as a lieutenant general.)

Mill 1680 was officially launched on May 1st. And in 1940, Zaporozhye already produced 1,500 tons of steel sheet per day, or about 600 thousand tons per year.

There are two metallurgical plants in Ukraine where the production of cold-rolled strips is organized: the metallurgical plant Zaporizhstal (Zaporozhye) and the metallurgical plant in Mariupol. The Zaporizhstal steel plant operates a continuous broadband mill (SHSHP) 1680, two reversing mills 1680 and 1200 with four-roll stands, one twenty-roll mill 1700, two continuous rolling mills for sheet metal with barrels 450 and 650 and a single-stand mill 2800.

& nbsp metallurgical plant a continuous four-stand SHSHP 1700 operates.

& nbspTechnical characteristics of ShSKhP 1680 and 1700 are presented in table. 4.1.

& nbspLearn more technological process production of strips in the cold rolling shop of the Zaporizhstal steel plant (Fig. 4.1). Hot-rolled coils from the hot-rolling shop of thin strips through underground conveyor 33 are fed to the warehouse to continuous pickling units (NTA) 1-3, in which strips of adjacent coils are butt-welded into an endless thread. During the movement of the strip in the NTA, mechanical cracking of the scale and its subsequent removal in baths with sulfuric acid (hydrochloric acid) solution are sequentially performed. After removing the solution by hot and cold rinsing,

& nbsp Rice. 4.1 - Layout of equipment of cold rolling shop No. 1 with a continuous four-stand mill 1680.

& nbsp1 - pickling line No. 1; 2 - pickling line No. 2; 3 - pickling line No. 3; 4 - continuous four-stand mill 1680; 5 - reversing mill 1680; 6 - reversing mill 1200; 7 - bell-type one-stop furnaces; 8 - temper mill 1700 # 1; 9 - tempering mill 1700 # 2; 10 - cut-to-length unit No. 1; 11 - cut-to-length unit No. 2; 12 - cut-to-length unit No. 3; 13 - cut-to-length unit No. 4; 14 - quarto stand; 15 - hardening line No. 1; 16 - N2 hardening line; 17 - 20 - roll mill; 18 - mechanical workshop; 19 - H / sh. local 20-roll mill; 20 - strip grinding unit; 21 - H / sh. plot; 22 - cutting unit; 23 - pantry; 24 - washing unit; 25 - electric furnaces; 26 - 4-stand mill 450 OBZh; 27 - 4-stand mill 650 OBZh; 28 - unit for dissolving OBZH; 29 - stan duo No. 1,2,3,4 LIFE SAFETY FUNDAMENTALS; 30 - units for hot tinning OBZH; 31 - slitting unit; 32 - workshop of power engineers; 33 - underground conveyor; 34 - warehouse of spare parts for mechanical service.

& nbsp Table 4.1. Characteristics of ShSKhP 1680 and 1700

Indicators	Continuous SHSHP
	1680	1700
Number of stands, pcs. Roll weight (single), t. Roll thickness, mm Finished strip thickness, mm Strip width, mm Roll diameter, mm: Workers Support Powermain engines of each stand, kW Rolling speed, m / s Workers Truss (barrel) Reference (axis) Roll surface hardness (Shore),HSD: Workers Support	4 5.5-7,5 0,5-2,0 1000-1500 9X2MF 60 X2 MF 40ХН2МА	4 1,8-4,0 0,45-2,0 1000-1500

followed by drying of the strip surface and oiling it with an emulsion of a high-performance synthetic lubricant.

The hot-rolled strip prepared for rolling is cut to lengths to form enlarged (double) coils weighing ~ G = 11-15 tons.

& nbsp

& nbspС NTA pickled coils are sent for rolling to a continuous mill 1680, to reverse mills 1680 and 1200, or to a reversible twenty-roll reversing mill 1700 of the Sendzimir type. Mills 1680 are designed for rolling low-carbon strips (08KP, 08Yu, 10PS, 15PS, 20PS, 20, 25, St.3SP, etc.) and low-alloy strips (09G2, 10KhNDP, 10G2, 16G2, 08GSUF, etc.) with a thickness of 0.5 -2.0 mm. On mill 1200, low-carbon steel with a thickness of 0.5-0.6 mm is rolled, and mill 1700 is designed for rolling strips with a thickness of 0.8-1.6 mm from alloyed and stainless steels(12Х18Н10Т, 10Х14АГ15, 08Х18Т1, 12Х21Н5Т, 09Х16Н4Б, etc.)

& nbspAs a result of the total deformation of the strips within the limits, the metal is strengthened and practically loses its plastic properties. Therefore, the coils of cold-rolled strips are transferred to the thermal department, where recrystallization annealing is performed in bell-type furnaces 7. The coils are annealed in a protective atmosphere that prevents oxidation of the strip surface. The duration and temperature of annealing are determined by the thickness and chemical composition material strips. In order to prevent sticking (welding) of the turns of the coils during annealing, roughness is applied to the surface of the strips in the finishing stand of the continuous mill with notched rolls. After annealing at temperatures t = 670 - 710 ° C, the flow stress of steel grades 08kp (08 ps) decreases from s t = 700 - 750 N / mm 2 to s t = 220 - 240 N / mm 2, and the elongation increases with d = 1.5% to d = 35 - 40%.