Rolling equipment. Rolling production products, equipment and tools. Auxiliary equipment for rolling production
1.5. Rolling
Rolling is a method of processing metals by pressure, which consists in compressing the workpiece between rotating rolls.
Rolling production is of great importance in national economy, since about 90% of all steel produced and most of the non-ferrous metals are rolled.
Due to the continuity of the process, rolling is the most productive method of metal forming.
Depending on the location of the rolls and the workpiece, three main types of rolling are distinguished: longitudinal, transverse and cross-helical.
During longitudinal rolling (Fig. 5, a), the workpiece is deformed between two rolls and moves perpendicular to the axes of the rolls. This is the most common rolling method.
During transverse rolling (Fig. 5, b), rollers rotating in one direction impart rotation to the workpiece, which, moving along the axis of the rolls, is deformed.
During cross-helical rolling (Fig. 5, c), the axes of the rolls are located at an angle to each other and impart rotational and translational movements to the workpiece during deformation.
Rolling tools and equipment
Rolling tools are rollers. Depending on the profile being rolled, they can be smooth (Fig. 6, a) or calibrated (ribbed) (Fig. 6, b).
The roll consists of a middle working part - barrel 1, which carries out rolling, necks 2, which are installed in bearings and clubs 3, through which the roll rotates.
Smooth rolls are used for rolling sheet steel and firing ingots into a square billet (bloom) or rectangular billet (slab).
Calibrated rolls have cutouts on the working surface of the barrel. The profile formed by the surface of the cut and forming the roll is called a stream, and the figure formed by the combination of two streams of a pair of rolls is called a caliber. A set of rolls installed in a special frame is called a stand.
The combination of the drive for rotation of the rolls, one or more working stands, and feed rollers forms a rolling mill.
Rolling mills are divided according to their purpose into mills producing semi-finished products and mills for producing finished products.
The first include crimping mills (blooming and slab mills) for rolling ingots into large-section billets, which are subsequently used for rolling long products and sheets.
The second includes mills for rolling sheets, shaped profiles, rails, pipes, etc.
Products rolling production
Rolled products are used in metal structures (bridges, buildings, reinforced concrete structures, railway tracks, machine beds, etc.) as blanks for the manufacture of parts by cutting in machine shops and blanks for subsequent forging and stamping.
The cross-sectional shape of a rolled product is called a profile. A set of profiles of various sizes is called an assortment. The range of rolled products is divided into four main groups: long products, sheets, pipes and special types of rolled products.
Long products obtained by longitudinal rolling are divided into rolled products of simple geometric shapes - square, circle, hexagon, strip (Fig. 7, a); general purpose shaped steel - I-beam, channel, angle, T-beam, rail (Fig. 7.b) and rolled products special purpose(Fig. 7, c).
Rolled sheets, depending on their purpose, are divided into electrical, shipbuilding, boiler, automotive, and tin for the canning industry. In addition, sheet steel is divided into thick sheet (4...160 mm thick) and thin sheet (4...0.2 mm thick). Depending on the production technology, thin sheet metal can be hot-rolled or cold-rolled.
Steel pipes are divided into seamless with a diameter of 30...650 mm and welded with a diameter of 10...1420 mm.
Special types of rolled products include wheels of railway cars, gears, ball bearings, periodic profiles, which are a workpiece whose shape and cross-section periodically change along the axis.
A special variety of special types of rolled products are cold-formed profiles (Fig. 8), manufactured on roller bending mills from strip. The use of such profiles by increasing the rigidity of structures in construction and mechanical engineering instead of hot-rolled ones allows saving up to 40% of metal.
1.6. Drawing
Drawing involves pulling the workpiece through a tapering hole in the die. In this case, the cross-sectional area of the workpiece decreases and takes the shape of the cross-section of the die hole.
Schemes of the process of drawing a solid round or shaped profile are given in Fig. 9, a, and for a round pipe on a mandrel - in Fig. 9, b.
The drawing tool - die (matrix) is made of hardened steel, hard alloys, and for particularly thin products, diamond inserts are made. Drawing forces significantly influence the friction forces on the surface of the workpiece metal - matrix, which tend to be reduced by the use of lubricants (mineral oils, talc, graphite, soap).
The drawing process is usually carried out in several passes. In most cases, drawing is carried out without heating, i.e. in a cold state. During the drawing process, the metal is strengthened. Therefore, before each subsequent pass, annealing (heating with slow cooling) is carried out to remove the hardening.
Using the drawing method, wire is produced from steel and non-ferrous metals, which is widely used in technology (cables, springs, electrical wires, welding electrodes, etc.), rods and profiles of complex cross-section, pipes with a diameter of 0.3 to 220 mm with a thickness walls from 0.05 to 6 mm.
1.7. Pressing
Pressing involves squeezing metal out of a closed cavity through a hole corresponding to the cross-section of the profile being pressed.
A schematic diagram of pressing is shown in Fig. 10. During the pressing process, the pressed metal I is squeezed out through the matrix 2 from the container 3 when the punch 4 moves.
Pressing can be carried out by the direct method, in which the finished product moves in the same direction as the punch (Fig. 10, a) and the reverse method, in which the finished product moves towards the punch (Fig. 10, b). The direct pressing method is used much more often in practice.
The starting material for pressing is an ingot or rolled product.
Pressing is used to produce a wide range of products from structural, stainless and other steels and non-ferrous metals. This method produces rods of various sections with a diameter of 3 to 250 mm, pipes with a diameter of 20...400 mm with a wall thickness of 1.5...12 mm, hollow profiles of complex cross-section, etc.
When pressing, the metal is deformed under conditions of all-round compression, as a result of which it shows maximum ductility. Therefore, pressing can process metals that, due to their low ductility, are impossible or difficult to subject to other types of pressure treatment.
The disadvantages of pressing include large metal waste, since all the metal cannot be squeezed out of the container and press residue remains in it (up to 40% of the weight of the original workpiece). Due to high pressing forces and high temperature The pressing tool wears out quickly. To reduce wear, it is made from expensive high-alloy heat-resistant steels, and special lubricants are used (for example, liquid glass).
The main equipment for pressing are vertical or horizontal hydraulic presses.
The main tool for rolling are rollers, which, depending on the profile being rolled, can be smooth (Fig. 3.20, a) , calibrated (stream) (Fig. 3.20, b) and special. Smooth rolls are used for rolling sheets, strips, etc. All types of long products are rolled on calibrated rolls. Special rolls are used in the production of special types of rolled products.
The rollers have a working part (barrel) 1, two necks 2 for installation in bearings and cross-shaped ends (clubs) 3 for connecting the roller to the drive (Fig. 3.20).
On the working (side) surface of the calibrated rolls there are grooves - streams. The set of streams of a pair of rolls is called a caliber . Each pair of rolls usually contains several gauges. Calibers can be open (Fig. 3.20, c) and closed (Fig. 3.20, d).
The rollers are supported by their necks on bearings installed in the frame. Using a special pressure mechanism, the distance between the rollers can be adjusted. A set of rolling rolls with a frame is called a working stand. A rolling mill consists of one or more working stands and a drive, including an electric motor and a transmission mechanism (Fig. 3.21).
Depending on the design and location of the rolls, the working stands of rolling mills are divided into six groups (Fig. 3.22): duo, trio, quarto, multi-roll, universal and special design.
Duo (two-roll) stands are reversible (rolling is carried out in both directions) and non-reversible (rolling is carried out in one direction). Trio (three-roll) stands are most often non-reversible. Rolling in such mills is carried out forward between the lower and middle rolls and backwards between the upper and middle ones. Quarto (four-roll) stands have four rolls located one above the other, of which two work rolls are of smaller diameter and two support rolls are of larger diameter. Due to the rigidity and relatively low deflection of the support rolls, these stands produce cold rolling of thin strips and narrow strips with a small thickness tolerance. Universal stands have horizontal and vertical rolls: the latter provide compression of the metal in the transverse direction. Vertical rollers are usually located on the front side. Stands of special design include stands of rolling mills for narrow purposes: wheel-rolling, bandage-rolling, ring-rolling, ball-rolling, mills for rolling profiles of variable cross-sections.
Based on the type of products produced, rolling mills are classified into the following main types: crimping, billet, rail and beam, section, wire, sheet, pipe and special purpose mills.
Crimping mills designed for compressing steel ingots into large billets. Crimping mills include blooming mills that produce square profiles - blooms and slabs that produce rectangular rolled products - slabs.
Procurement mills used for rolling blooms into billets, mainly of square cross-section, which are subsequently used for rolling on section mills.
Rail and beam mills are used to produce rails, large beams, channels and other profiles from blooms.
Longitudinal mills, used for the production of long rolled products of simple and shaped profiles.
Wire mills designed for rolling wire with a diameter of 5 ... 10 mm.
Sheet rolling mills, divided into thick-sheet and thin-sheet. Plate mills roll sheets with a thickness of more than 6 mm. The blanks are slabs.
Pipe rolling mills used for the production of seamless and welded pipes.
Special mills designed for producing blanks of special and periodic profiles. Balls, ribbed tubes, carriage axles, gear wheels and many other products of complex configuration are rolled on special mills.
rolling tool are rolls, with the help of which ingots and other workpieces are processed. There are rollers:
smooth for rolling sheets, tapes;
stepped for rolling strip steel;
brook to obtain long products.
The cutout profile on the side surface of the roll is called stream. The stream of the upper and lower rolls together form caliber.
Several gauges are placed on each pair of rolls, the shape of which depends on the profile being rolled. Complex rolled profiles are obtained by successively passing the metal through a series of gauges. For rails the number of gauges is 9, for beams from 9 to 13, for wire - from 15 to 19.
Depending on the rolling stage there are different crimp gauges ( reducing the cross-section of the workpiece), rough(bringing the cross-section of the workpiece closer to a given profile) and finishing or finishing(giving a given profile).
Equipment where metal is rolled is called a rolling mill. Working principle of rolling mill next: rolling rolls are mounted in bearings located in the frame posts. A set of rolls together with a frame is called a working stand. The work rolls receive rotation from the motor through a gearbox that transmits rotational motion through the gear cage and spindles.
The rolling mill also includes auxiliary machines and mechanisms that perform auxiliary operations of cutting, finishing and transporting the rolled metal.
§ 3. Classification of rolling mills
Countries are classified according to 3 main characteristics:
by appointment;
by the number and location of rolls in the working stands;
3. by the number and location of working stands.
By purpose Mills are divided into 2 main types:
mills for the production of semi-products;
mills for the production of finished products.
First type relate crimping and blanking mills. Crimping machines – bloomings and slabs with a roll diameter of 800–1400 mm – designed for rolling ingots into large-sized billets (blooms and slabs), which are supplied as a semi-product for subsequent rolling into smaller-sized billets or to obtain the finished product. Billet mills with roll diameters of 450–750 mm are designed for rolling blooms into smaller workpieces (from 50 
50 mm to 150 
150 mm), which are source material for further rolling on section mills.
To the second type of mills include:
1. rail and beam with rolls with a diameter of 750 – 900 mm for rolling
railway rails, I-beams, channels, angles
large sizes;
2. large-section with rolls with a diameter of 500–750 mm for rolling large-section steel (square and round from 80 to 150 mm), beams and channels 120–140 mm;
3. medium-grade with rolls with a diameter of 350–500 mm for rolling medium-grade steel (square and round 40–80 mm), beams and channels up to 120 mm high;
4. small sections with rolls with a diameter of 250–350 mm for rolling small sections (square and round 8–40 mm), corner sections 20 
20 to 50 
50 mm;
5. wire mills with rolls with a diameter of 250–300 mm for rolling wire (rod rod) with a diameter of 5–9 mm;
6. strip (strip) mills with rolls with a diameter of 300–400 mm for rolling strips 65–500 mm wide and 1.5–10 mm thick;
7. thick-sheet mills for rolling sheets with a thickness of 4–60 mm;
8. thin-sheet hot and cold rolling for sheets with a thickness of 0.2–4 mm and a width of 500–2500 mm;
9. universal mills for rolling universal strips with a width of 200–1500 mm;
10. pipe mills for the production of seamless and welded pipes;
11. Special purpose mills – wheel and bandage rolling, ball rolling, etc.
As can be seen from the above classification, the main characteristic of section mills is the diameter of the working or gear rolls. If the mill has several stands, then the diameter of the finishing stand rolls is a characteristic of the entire mill. For example, a wire mill of 250 means that the diameter of the work or gear rolls of the finishing stand is 250 mm.
According to the number and location of rolls in the working stands of the mills differentiate:
duo-mills – (two-roll) with two rolls in each stand located horizontally one above the other in a vertical plane.
Duo mills can have a constant direction of rotation of the rolls (irreversible) and a variable direction (reversible). In the latter case, the rolls periodically change the direction of rotation and the ingot or strip passes back and forth between the rolls several times; both rolls are usually driven. Reversible duo-mills have become more widespread: blooming, slab, thick-sheet, etc.
Trio mills, in which three rolls are located horizontally one above the other in the same vertical plane. The strip is rolled first between the lower and middle rolls, and then a special device (lifting-oscillating tables) is raised to the level of the middle and upper rolls and, during the reverse stroke, is rolled between the middle and upper rolls. Sectional metal and sheets are rolled on trio mills. Sheet trio mills have a middle non-driven roll of slightly smaller diameter than the upper and lower ones, and on section mills all rolls are of the same diameter.
quarto mills have four rolls, vertically located one above the other, two rolls of smaller diameter (middle) are working, and large (upper and lower) are support. The support rolls absorb the rolling pressure and reduce the deflection of the work rolls. Quarto mills can be reversible or non-reversible. They are designed for rolling sheets and strips.
multi-roll mills are six-roll, twelve-roll, twenty-roll, etc. These mills have two small-diameter work rolls, and the rest are support rolls. Due to the low deflection of the work rolls, these mills are used for cold rolling of thin strips and narrow strips in coils.
universal mills that have vertical and horizontal rolls in one working stand. On these mills, the metal is compressed in width and height. Universal mills are used for rolling strips called universal steel.
According to the number and location of working stands rolling mills separate on single-cell and multi-cell. The simplest type is the single-stand mill. These include blooming, slab mills, thick-sheet duo- and trio-mills, and universal mills.
Multi-stand mills have two or more working stands. The arrangement of the cages can be: linear, sequential and continuous. In these mills, each working stand or group of 2–4 stands has a roll drive line.
Linear mills with working stands arranged in one line are rail and beam mills and large-section mills.
The most common type of modern multi-stand mills are continuous mills, in which the number of working stands is equal to the required number of passes; Rolling is carried out according to the principle of one pass in each stand. The cages are arranged sequentially one after the other so that the strip is simultaneously in two or more cages. The rolling speed in each working stand increases as the cross-section of the rolled strip decreases, which is achieved by changing the number of rotations of the rolls with individual drive of the rolls of each working stand, or by changing the gear ratio and the number of rotations of the rolls and the diameter of the working rolls with a group drive.
Continuous mills are used as billets, sections, wire mills, strip mills, and sheet mills for cold and hot rolling. The rolling speed on these mills reaches 30–35 m/sec or more, due to which continuous mills have high productivity.
RENTAL PRODUCTS
The cross-sectional shape of the rolled strip is called profile. The set of shapes and sizes of profiles obtained by rolling is called assortment . The DSTU for the range of rolled products shows the cross-sectional area, dimensions, weight of 1 m of profile length and permissible deviations from the nominal dimensions. The range of rolled profiles is divided into four main groups : long products, sheets, pipes and special types of rolled products.
Long products are divided into profiles simple geometric shape (square, circle, hexagon, rectangle) and shaped(channel, rail, corner and T-profiles and round and square steel are rolled, respectively, with a diameter or square side of 5-250 mm; hexagonal - with an inscribed circle diameter of 6-100 mm; strip - -200 mm wide and 4-60 mm thick. Non-ferrous metals and their alloys are rolled mainly into simple profiles - round, square, rectangular. Sheet steel is divided according to purpose into automotive, transformer, roofing sheet, etc. Based on the type of coating, sheet steel is divided into zinc-coated, aluminum-coated, plastic-coated, etc. In addition, sheet steel is divided into thick sheet (thickness 4-160 mm) and thin sheet (thickness less than 4 mm), thickness less than 0.2 mm is called foil. Pipes are divided into seamless and welded. Seamless pipes are rolled with a diameter of 30-650 mm with a wall thickness of 2-160 mm from carbon and alloy steels, and welded pipes with a diameter of up to 2500 mm with a wall thickness of 0.5-16 mm from carbon and low-alloy steels. Special types of rolled products include wheels, balls, periodic profiles with periodically changing shape and cross-sectional area along the axis of the workpiece .
The rolling tool is rolls, which, depending on the profile being rolled, can be smooth, used for rolling sheets, strips, etc., stepped, for rolling steel strip, and strand, to obtain long products. A groove is a cutout on the side surface of a roll, and the combination of two streams forms a caliber . Each pair of groove rolls usually forms several calibers. A set of rolling rolls with a frame is called a working stand; the latter, together with the spindle for driving the rolls, gearbox, couplings and electric motor, form the working line of the mill. Working stands, according to the number and arrangement of rolls, can be two-roll, four-roll, which have 2 working rolls and two support rolls; multi-roll , which also have two working rolls, and the rest are support rolls. Rolling mills can be single-stand (with one working stand) or multi-stand. The most advanced multi-stand mills are continuous, in which the working stands are arranged sequentially one after the other. The rolled strip passes through each stand only once, i.e. the number of working stands of these mills is equal to the required number of strip passes. The maximum rolling speed on continuous mills is 50-60 m/s. By purpose Rolling mills are divided into mills for the production of semi-products and mills for the production of finished products. The first group includes crimping mills for rolling ingots into semi-products of large cross-sections (blooming mills, which produce blanks for long products, and slabs, which produce blanks for sheet metal) and billet mills for producing semi-products of smaller cross-sections. Mills for the production of finished rolled products include long products, sheets , pipe and special. The size of bloomings, slabs, billet and section mills is characterized by the diameter of the roll barrel (for example: blooming 1500; section mill 350); the size of sheet mills is the length of the barrel (for example: mill 3600), and the size pipe rolling mills- outer diameter of rolled pipes.
7.1. Types of rolling mills
A set of machines and mechanisms for producing products by rolling and processing them in a flow is called a rolling mill.
From this definition it follows that in addition to the main operation - plastic shaping of the rolled product, a number of others are also performed on the mill.
In the theory of production organization, the individual operations necessary to implement technological process, are divided into main accompanying and auxiliary. In accordance with this, a distinction is made between main, auxiliary and auxiliary equipment.
In relation to rolling, the main operations include plastic deformation of the metal, i.e. rolling itself, and accordingly the main equipment includes a rolling stand, an electric drive and transmission devices.
Related operations include operations during which the physical state and/or dimensions of the rolled product may change, but without changing the shape and cross-sectional area. This includes heating, cooling, cutting into cut lengths, straightening, stripping rolled products, etc. And, accordingly, equipment: heating devices, refrigerators, leveling machines, cutting and finishing equipment, etc.
Auxiliary operations include operations in which neither the shape, nor the dimensions, nor the physical state of the rolled metal are changed. These are operations and corresponding equipment for the longitudinal and transverse movement of rolled products (roller tables, slappers, lifting mechanisms), their edging and branding, winding into coils and rolls, tying rolled products, transfer of rolls, etc. In everyday life, however, related and auxiliary operations and equipment is usually referred to as auxiliary equipment.
The line on which the main equipment is located is called the main (working) line of the rolling mill (Fig. 7.1). Its main elements are: a working cage with rolls (1), spindles with couplings (2), a gear cage (3), a main clutch (4), a gearbox (6), a main (motor) clutch (7) and an engine (5) .
Rolls (Fig. 7.2) consist of a barrel (1) with diameter d and length l, two support journals (2) and shanks (3). The size and number of rolls in a stand determine the type of stand and rolling mill. Section mills are characterized by the nominal diameter of the roll barrel (for example, mill 280), and sheet mills are characterized by its length (for example, mill 3600). If a section mill consists of several stands with different roll diameters, the type of mill is usually determined by the finishing stand rolls.
Rolling mills are classified according to the following criteria: by operating mode, by purpose, by the number and arrangement of rolls in the stand, by the number and arrangement of stands.
By mode Rolling mills are divided into non-reversible (the frequency and direction of rotation of the rolls are constant) and reversible (rolling is carried out in the forward and reverse directions by changing the direction of rotation of the rolls). The latter include blooming, slab mills, billet and plate mills.
By purpose mills are divided into mills for the production of semi-products and mills for the production of finished products. The former include blooming machines, slabs, and billet mills. The second include:
Rail and beam mills (roll diameter 750-900 mm);
Large section mills (500-700 mm);
Medium-grade mills (350-500 mm);
Small section mills (250-330 mm);
Wire mills (150-280 mm);
Strip mills (300-400 mm);
Thick plate mills (roll barrel length up to 5500 mm);
Wide-strip hot rolling mills (up to 2500 mm);
Wide-strip cold rolling mills (up to 2800 mm);
Universal strip mills (up to 2000 mm);
Tube mills different types;
Other mills (wheel-bandage, axle rolling, ball rolling, etc.)
By number and location of rolls in the cage there are:
Double-roll (duo) stands (see Fig. 1.1). Widely used in reversible and non-reversible modes.
Three-roll (trio) stands, high-quality (7.3 a) and sheet (Fig. 7.3 b). Used for rolling blanks, grades and sheets.
Double two-roll stands (double duo). Rarely used, mainly for rolling small grades of alloy steel (Fig. 7.4).
Four-roll stands (quarto). Used mainly in sheet production (Fig. 7.5). The work rolls (2) are of smaller diameter, the support rolls (1) are of larger diameter to increase the rigidity of the system.
Six-roll stands (Fig. 7.6) are rarely used. The option of placing the rolls is in one vertical axial plane. The drive rolls are working.
Multi-roll stands – 12 and 20 rolls. Used for rolling the thinnest strips (up to 2 microns) in rolls (Fig. 7.7. - 7.8). The diameter of the work rolls is up to 50 mm. The drives are support rollers.
Universal stands - for rolling sheets, in addition to horizontal ones, they are equipped with two vertical drive rolls; for rolling wide-flange beams, idle vertical rolls are placed in the same vertical plane as the horizontal ones (Fig. 7.9).
By number and location of cages Rolling mills are divided into single-stand and multi-stand. Single-stand – blooming, slab, sheet-rolling, crimping-blanking, etc. mills (Fig. 7.10).
Multi-stand mills - linear type, continuous, semi-continuous and with a sequential arrangement of stands.
Linear-type mills (Fig. 7.11) are used for rolling billets, small-, medium- and large-grade profiles. The disadvantage of such mills is high costs manual labor, low speeds rolling and productivity. These disadvantages can be partially avoided by placing the stands in several lines (Fig. 7.12.).
Continuous mills with stands located one behind the other are more advanced (Fig. 7.13). Such mills operate on the principle: “one pass in each stand.” The roll can be in several cages at the same time. Therefore, it is necessary to observe the rule of so-called second volumes, i.e. the same amount of metal must pass through each cage per unit time: , where V And F– speed and cross-sectional area of the roll along the stands, respectively. If this condition is violated, stretching of the roll or a loop may occur between the stands. Therefore, predominantly simple profiles are rolled in continuous mode.
The principle of continuous rolling is used in continuous billet mills, medium- and small-section mills, wire mills, strip mills, wide-band hot and cold sheet rolling mills, etc.
For rolling more complex profiles, semi-continuous mills and mills with sequential stands are used. Semi-continuous mills are used for rolling small grades. They combine continuous roughing and linear finishing groups of stands (Fig. 7.14).
In mills with a sequential arrangement of stands (Fig. 7.15), the roughing group can be continuous, and subsequent stands are located one after another at a distance exceeding the length of the roll. To reduce the total length of the mill, the stands are placed in several parallel lines. In these cages there is no need to follow the rule of second volumes. Such mills are used mainly for rolling medium and large grades.
A variety of such mills is a mill with a staggered arrangement of stands (Fig. 7.16)
7.2 Main and auxiliary equipment of rolling mills.
The working cage consists of two frames, rolls with bearings, mechanisms for installing and fixing the position of the rolls in the vertical and horizontal planes, roll fittings, devices for lubrication and cooling of the rolls.
Beds of open or closed types (Fig. 7.17) are cast from steel grade 30...35L of I-beam or rectangular section.
Closed-type beds in the form of a solid frame can withstand high rolling forces, but are less convenient to use: transfer of rolls is difficult, their diameter is limited by the width of the window.
Rolling rolls, the main deforming tool, operate under harsh conditions: sudden heat changes, high pressures, abrasive friction, etc. Therefore, they must be not only high-strength, but also heat- and wear-resistant.
According to the material, rolls are divided into steel (cast, forged) and cast iron. Steel rolls have sufficiently high strength and ductility, so they are used in stands that experience high rolling forces. Cast iron rolls are less durable, but more wear-resistant than steel ones. Therefore, they are more often used in pre-finishing and finishing stands.
The roll materials are carbon, low-alloy and alloy steels (St. 50...55, 50...60KhN, 9KhF, etc.), alloyed and unalloyed cast iron (SShKhN-60, LPKhN-60, etc.). The letters S, L indicate varietal and sheet rolls; Ш, П – cast iron with nodular or lamellar graphite; X, N – alloyed with chromium and nickel, respectively; 60 – hardness, Shore units.
When loading into the cage and during operation, the position of the rolls must be adjusted. Roll installation mechanisms are used for this purpose.
These include a pressing device, a balancing device and a device for adjusting the position of the rolls in the axial direction.
The pressure device is used to regulate the position of the rolls in the vertical plane. It consists of a nut (phosphor bronze), fixed in the upper cross member of the frame, and a pressure screw (forged steel 40...45 HN).
Pressure screw drive – manual on mills with small movement of the upper roll (50-100 mm), electromechanical – on mills with frequent and large
