Private reductions for mill 2500. Pickling section
The starting material for the production of hot-rolled sheets is hot-rolled strips with a thickness of 1.5-6.0 mm, a width of 1250-2300 mm, rolled into rolls weighing from 2 to 30 tons, which come from the hot rolling shop along a conveyor. In the workshop, rolls are removed from the conveyor by overhead cranes and placed in a warehouse for cooling. After cooling, the rolls are processed:
- Ш cleaning the strip from scale by mechanical and chemical means in continuous pickling units;
- Ш cold rolling on a continuous four-stand mill to a final thickness of 0.6-2.5 mm;
- Ш annealing of rolls at a temperature of 620-720°C in single-stop bell furnaces in a nitrogen protective atmosphere;
- Ш training of strips with a reduction of 0.7-3% on a temper rolling mill;
- Ш trimming edges and cutting strips into sheets, sorting sheets, stacking, weighing bundles, packing and tying bundles in cross-cutting units; strip slitting, strip control, coiling, tying, packaging, weighing in slitting units;
- Ш shipment of finished products.
Cold rolling mill 2500
The continuous 4-stand mill "2500" is designed for rolling pickled hot-rolled strips.
The rolled stock for a cold rolling mill is a pickled hot-rolled strip with a cutting edge, an oiled surface, and wound into a roll. Roll thickness 1.5-6.0 mm, width 1000-2350 mm. The inner diameter of the roll is 730-830mm, the outer diameter is up to 1950mm. Maximum roll weight 30t.
The equipment of the 4-stand mill includes:
- Ш receiving conveyor;
- Ш lifting roller conveyor with pusher;
- Ш installation of centering and pressure rollers;
- Ш drum unwinder with scraper bender, with correct feeding rollers;
- Ш four working stands with wiring fittings, drives and transfer mechanisms;
- Ш support rollers,
- Sh the giver;
- Winder with pressure roller;
- Sh overwhelm;
- Ш roll remover;
- Ш roll contactor;
- Ш outgoing conveyor; storage conveyor.
Tempering of cold-rolled strips on mills 2500 and 1700
The purpose of the training is to prevent the appearance of shear lines during the stamping process of products at the consumer, final straightening, finishing the surface of cold-rolled strips after annealing and improving the mechanical properties of the metal.
Introduction 2
A brief overview of composite mill rolls. Characteristics of mill 2500. Mill assortment. 3
1.1 Brief overview and analysis of composite mill roll designs 3
1.2 Characteristics of hot rolling mill 2500 8
1.3 Mill range by steel grades and strip sizes 9
Research and development of the design of the banded back-up roll of the 2500 hot rolling mill 10
2.1 Selection of tension, shape, thickness of the bandage and calculation of the load-bearing capacity of the connection 10
2.2 Calculation of stresses in a banded support roll 17
2.3 Calculation for the frequency of use of the axis of a composite support roll 31
2.4 Determination of cyclic endurance in section 1-1 33
2.5 Determination of cyclic endurance in section 2-2 37
2.6 Determination of the slip and deflection zone of a composite and solid support roll 37
2.7 Determination of deflection of a solid support roll 38
2.8 Determination of deflection and slip zone for a composite support roll 39
2.9 Development of measures to prevent fretting - corrosion on sedimentary surfaces and increasing the surface of the roll 47
2.10 Study of the influence of mating coatings on the load-bearing capacity of the axle-tire connection. Selection of material and coating technology. 48
2.11 Selecting the material of the axle and bandage and methods of their heat treatment 52
Economic justification for the project 57
4.1 Calculation of the production program 57
4.2 Calculation of capital cost estimates 59
4.3 Organization of labor and wages 60
4.4 Calculation of contributions for social needs 63
4.5 Calculation of product costs 64
4.6 Calculation of main technical and economic indicators 65
Conclusion 68
List of sources used 70
Introduction
The purpose of this thesis is to develop the design of composite support rolls, ensuring their reliability during operation, increasing their durability and reducing cost.
Rolls are the main element of the rolling stand, with the help of which the rolled strip is compressed. The requirements for rolling rolls are varied and relate not only to their operation, but also to the manufacturing process. The rolling roll operates under the simultaneous influence of rolling force, torque, temperature in the deformation zone, etc. Therefore, one of the main requirements is high wear resistance and thermal fatigue strength, which determines low and uniform wear of the rolls.
One of the ways to increase the durability of rolling rolls and reduce their metal consumption is to use composite rolls. The use of tires made of high-strength materials and the possibility of replacing worn tires when using the axle repeatedly will give a great economic effect.
Currently, in the 5.6 finishing stands of the 2500 mill of OJSC MMK, support rolls of 1600x2500 mm are used, which are made of forged steel 9HF. In this work, it is proposed to use composite rolls with a band made of cast steel 150ХНМ or 35Х5НМФ. It is proposed to use used solid forged rolls as axles. Experience in operating rolls made of similar materials shows that their wear resistance is 2-2.5 times higher than forged ones. The connection of the tire to the axle is carried out by a fit with guaranteed interference. In order to increase the transmitted torque, it is proposed to apply a metal coating to the seating surface of the axle, which significantly increases the coefficient of friction, the area of actual contact between the axle and the tire, and its thermal conductivity.
A brief overview of composite mill rolls. Characteristics of mill 2500. Mill assortment.
1.1 Brief overview and analysis of composite mill roll designs
The main advantages of composite rolls:
the ability to produce a bandage and axle from materials with different mechanical and thermophysical properties;
the ability to replace a worn bandage when using the roll axis repeatedly;
Heat treatment of the axle tire can be carried out separately, which makes it possible to increase hardenability, obtain uniform hardness throughout the entire thickness of the tire and reduce the residual stress gradient, which is very high in a large solid roll.
The production of banded support rolls for sheet metal mills was mastered back in the 70s of the last century. The band and the axle are connected, as a rule, by a thermal method with a guaranteed fit; tires are made forged or cast, axles are forged; decommissioned rolls are usually used for their production. The hole in the bandage is most often cylindrical; the seat of the axle can be cylindrical, barrel-shaped, or similar in shape to reduce stress concentration at the ends of the bandage after assembly.
According to the method of fastening the tires, composite rolls can be divided into the following groups:
use of a fit with guaranteed interference;
the use of various mechanical methods of fastening the bandage;
use of light alloys and adhesive joints.
Many works of domestic and foreign scientists are devoted to improving designs, production and assembly methods, and increasing the technological characteristics of composite rolls. Much attention is paid to work to ensure a reliable connection of the tire to the axle.
For example, in the work it is proposed to use a composite rolling roll containing a tension band and placed on an axis with channels made in a spiral on the surface in contact with the band and a shoulder. The work proposes the use of rolls with a composite band made of sintered tungsten carbide. In a number of works in recent years, welded bandages made of high-alloy alloys are increasingly being proposed for use. In many cases, when simplifying the roll manufacturing technology and increasing the wear resistance of its surface, the cost increases significantly due to the use of a large number of alloying elements. Therefore, in order to increase the service life of rolls, many authors devote their work to improving the design of composite rolling rolls.
The work proposes composite rolls containing a bearing profiled axis and a band with a profiled inner surface, fitted with an interference fit with the possibility of free movement of its sections of smaller diameter in a heated state along the bearing axis through sections with a larger diameter along the length. Moreover, the generatrices of the surfaces of the barrel of the axle and the tire are made profiled in the form of a smooth curve according to certain dependencies (Figure 1,2). The disadvantages of such rolls include the complexity of their manufacture, the inability to control the required curvature of the profile of the seating surfaces, and in this case, the service life of the roll is also limited, caused by the small number of possible regrinds of the band, due to the occurrence of tensile stresses in the middle part from heating and thermal expansion of the bearing axis in process of rolling stand operation (Figure 2). But the main disadvantage can still be considered the complexity of the curves describing the profiles of the mating surfaces, which complicates the turning process, and the accuracy required when
And
x manufacturing is practically impossible with the technologies existing at machine-building plants.
Figure 1 – Composite rolling roll
Figure 2 – Composite rolling roll
IN 
work, in the conditions of the 2500 mill, OJSC MMK proposes to use a composite support roll, made in accordance with the diagram in Figure 3. The disadvantage of such a roll is the presence of a transition section of the axis from the shoulder to the conical part, which is a concentrator for increasing stress, which can lead to breakage of the axis at increased loads and deflection, as well as limiting its service life. In addition, this design is low-tech in production.
Figure 3 – Composite rolling roll
The objective of the proposed manufacture of a composite support roll is the simplest technical solution, which will increase the service life by ensuring constant tension along the entire length of the mating surfaces.
It is proposed to make the seat of the bandage and the axle cylindrical, from the point of view of simplicity and manufacturability. On the edges of the axle, make unloading chamfers - bevels, to reduce stress concentration. To increase the load-bearing capacity of the connection and the performance of the roll, the main attention should be focused on choosing the optimal tension value, developing measures that significantly increase the coefficient of friction on the mating surfaces and the thermal conductivity of the axle-tire contact.
When performing strength calculations, it is necessary to choose a technique that allows taking into account the influence of rolling forces on the stress-strain state of the bandage.
1.2 Characteristics of hot rolling mill 2500
The 2500 wide strip hot rolling mill consists of a loading section, a heating furnace section, roughing and finishing groups with an intermediate roller table between them and a winding line.
The loading area consists of a slab warehouse and a loading roller table, 3 lifting tables with pushers.
The heating furnace section consists of 6 methodical heating furnaces, a roller table in front of the furnaces with pushers, and a furnace roller table after the furnaces.
The roughing group consists of stands:
reversible duo cage;
quarto expansion cage;
reversible universal quarto cage;
universal quarto stand.
The finishing group includes flying shears, a finishing descaler (duo stand), 7 quarto stands. Devices for accelerated strip cooling (inter-stand cooling) are installed between the stands.
The intermediate roller conveyor ensures the discharge and separation of deficiencies (it is planned to equip the roller conveyor with encopanel-type heat shields).
The coiling line includes an outlet roller conveyor with 30 strip cooling sections (upper and lower showering), four winders, and trolleys with lifting and rotating tables.
1.3 Mill assortment by steel grades and strip sizes
The wide strip mill 2500 is designed for hot rolling of strips of the following steels:
carbon steel of ordinary quality in accordance with GOST 16523-89, 14637-89 steel grades in accordance with GOST 380-71 and current specifications;
weldable steel for shipbuilding according to GOST 5521-86;
high-quality structural carbon steel in accordance with GOST 1577-81, 4041-71, 16523-89, 9045-93 and current specifications;
alloy steel grade 65G according to GOST 14959-70;
low-alloy steel according to GOST 19281-89;
steel 7ХНМ according to TU 14-1-387-84;
carbon and low-alloy steel of export version according to TP, STP based on foreign standards.
Limit strip sizes:
thickness 1.8 10 mm;
width 1000 2350 mm;
roll weight up to 25 tons.
Research and development of the design of the banded back-up roll of the 2500 hot rolling mill
2.1 Selection of tension, shape, thickness of the bandage and calculation of the load-bearing capacity of the connection
The back-up roll 5 and 6 stands of hot rolling mill 2500 of OJSC MMK, in accordance with Figure 4, has the following main dimensions:
barrel length l=2500 mm;
maximum outer diameter of the barrel d=1600 mm;
minimum outer diameter d=1480 mm;
the diameter of the necks at the junction with the barrel is 1100 mm;
The seat of the bandage is cylindrical. At a distance of 100 mm from each edge of the axis, it is proposed to make unloading chamfers 10 mm high to reduce the stress concentrations of the bandage after assembly. This is explained by the fact that the bandage is connected to the axle by a thermal method, and when forming the connection, the edges of the bandage cool faster than its middle part, which leads to the appearance of stress concentration and provides an additional opportunity for the development of fretting corrosion and fatigue cracks in the future
Often, to prevent the bandage from slipping in the axial direction, a shoulder is made on the axis, and a groove is made on the bandage, or the seating surfaces are shaped like a cone. In this case, such devices are not used, since it can be assumed that if the mating surfaces are long enough, axial displacement will not occur, and the strength of the connection will also be ensured by guaranteed interference and a possible increase in the coefficient of friction on the surfaces due to the application of a metal coating or abrasive powder to them .
Also, this design is much simpler and cheaper to manufacture.
Analysis of factors influencing the choice of landing diameter shows that the region of optimal values of the ratio of landing and outer diameters fluctuates in the range d/d 2 =0.5...0.8.
If we talk about the choice of connection tension, then you may encounter disagreements. In practice, the optimal interference is usually taken to be 0.8-1% of the landing diameter: = (0.008 0.01)d. Some authors advise increasing it to 1.3%, and some, on the contrary, reducing it to 0.5%
For calculations, we will choose three different values of interference: 1 =0.8 mm; 2 =1.15 mm; 3 =1.3 mm.
Also, to compare and select optimal connection criteria, we will perform calculations for different friction coefficients and bandage thicknesses.
As mentioned above, the value of the friction coefficient can be changed by applying some kind of coating to the mating surfaces.
The greatest thickness of the bandage (d fit = 1150 mm) is determined by its passage through the necks of the rolling roll during assembly.
D fit > 1300 mm is not taken into account, since when the minimum outer diameter is reached (d 2 = 1480 mm), the bandage will become too thin.
Let's calculate some parameters of the load-bearing capacity of the connection under given conditions.
where K is the pressure on the landing surface, MPa;
F= dl – seating surface area, mm 2; (d and l are the diameter and length of the seating surface, respectively, mm)
f – coefficient of friction between mating surfaces.
The pressure K on the seating surfaces depends on the interference and the wall thickness of the female and male parts.
According to Lame's formula:
where d – relative diametrical interference;
- coefficient.
where E 1 = E 2 = 2.1x10 5 N/mm 2 – elastic modulus of the axle and bandage;
1 = 2 =0.3 – Poisson’s ratios for steel axle and tire
C 1 , C 2 – coefficients characterizing thin-walledness;
where d 1 and d 2 are the internal diameter of the axis and the outer diameter of the tire, respectively.
For this case, there is no hole in the axis - d 1 = 0, and we take the average diameter of the roll as the diameter d 2:
Then C 1 =1 (d 1 =0).
Maximum torque transmitted by the connection:
The compressive stress in the axis is maximum on the inner surface:
On the inner surface of the bandage the maximum tensile stresses are:
The calculation results are summarized in Table 1.
Conclusions: As you can see, the pressure K, and, consequently, the load-bearing capacity of the connection is proportional to the tension and inversely proportional to the coefficients C 1 and C 2, characterizing thin-walledness.
The difference in landing diameters is only 150 mm, but with the same interference fits, the difference in contact pressure is almost twice as large for a smaller diameter.
It should be noted that the compressive stress in the axis is also lower in the case of a thinner bandage, but the tensile stresses in the bandage remain practically unchanged with a change in its thickness.
Table 1 - Characteristics of rolling rolls 5,6 stands of mill 2000 and their load-bearing capacity at various values of diameters, interference, friction coefficients in the connection
|
d2=1600 (1480) dav=1540 |
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|
d=1150 (C2=3.52) |
d=1300 (C2=5.96) |
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|
rast=146.1 |
rast=210.1 |
rast=237.5 |
rast=129.2 |
rast=185.8 |
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Figure 4 - Composite rolling roll
With increasing friction coefficients, the load-bearing capacity of the connection also increases significantly, both in the case of d=1150 mm and with d=1300 mm, but in the case of d=1150 mm it is more maximum.
It is important that for all conditions the connection ensures transmission of torque with a good margin of safety
M etc cr
Moreover, the safety factor increases as the contact pressure in the connection increases, caused by interference.
In general, we can say that in both cases a good load-bearing capacity of the connection and fairly low stresses in the roll parts are ensured, but a bandage with an internal diameter d = 1150 mm is more preferable, due to a significant increase in the same load-bearing capacity.
2.2 Calculation of stresses in a banded support roll
The stresses in the composite back-up roll of the 2500 mill are determined for the same basic technical data specified in paragraph 2.1. It is required to determine the contact stresses on the seating surface of the bandage and the axle.
Let's denote the bandage area by S 2 , and the shaft area by S. Let's denote the radius of the mating surface after assembly by R, and the outer radius of the bandage by R 2 .
A force P is applied on the outer contour of the bandage C2, equal in magnitude to the metal pressure on the rollers P0. Taking P=P 0, we have a system of forces that are in equilibrium. The seating surface forms contour C.
The calculation scheme is presented in Figure 5.
Figure 5 – Calculation scheme for determining contact stresses in the roll
When solving a problem, it is convenient to determine stress in polar coordinates. Our task is to determine:
r – radial stresses
- tangential (circumferential) stresses
r - tangential stresses.
Calculations of stress components are usually quite cumbersome in general form and in calculations. Using the method of N.I. Muskhelishvili, in relation to the problem posed and carrying out a solution similar to that given in the work, the stresses on the seating surface of the bandage are determined in the form of formulas convenient for numerical implementation. The final expressions are:
where P=P 0 – specific load per unit length of the bandage from an external force;
R – radius of the contact surface;
h and g are series summed up in closed form, reflecting the peculiarity of the solution in the zones of points of application of concentrated forces P and allowing to improve the convergence of the series;
- angular coordinate of contour points C;
Muskhelishvili constant;
=0.3 - Poisson's ratio;
is the angle measured from the x-axis to the point of application of force P;
n=R 2 /R – coefficient characterizing the thickness of the bandage.
The last terms in formulas (9) and (10) represent stress components that depend on interference. Then the radial and tangential stresses in the composite roll are determined from two components, from the stresses caused by interference and normal load:
r = rp + r (12)
= p + (13)
Normal tension stresses are determined by the formula:
where K – contact pressure from interference (see Table 1), MPa;
n=R 2 /R – relative thickness of the bandage.
Calculation of stresses is carried out using the following formula:
where is half the interference value;
E – elastic modulus of the first kind.
As is known, there are no tangential stresses on surfaces due to tension.
Then the voltages rp , p and r can be represented as:
The values of rp, p and r were calculated on a computer for various values of n, some of which are given in Table 2.
The stress values are presented in the form of dimensionless coefficients C p, C , C , which should be multiplied by the value P/(R 2 x10 3), where P is the external load per unit length of the bandage, N/mm; R 2 – outer radius of the bandage.
To determine the stress components, it is necessary to know only n (the relative thickness of the bandage) and (the polar angular coordinate of the point at which the stresses are determined).
In accordance with Figure 5, under the given conditions that the main vector and the main moment of force P are equal to zero, the stress diagrams on the contact are symmetrical relative to the y-axis, that is, it is sufficient to determine the stresses in 2 of the 4 quarters, for example, in I and IV (from 3 /2 up to /2 rad).
The nature of the stress distribution along the axle – bandage contact is presented in Figures 6, 7, 8.
Table 2 – Stress components and radial, tangential, tangential stresses on the seating surface of the bandage from the influence of a force P = 1200 kg/mm of stands 5.6 of mill 2500
| | |||||||||||
|
N=1.34 (d=1150 mm) |
n=1.19 (d=1300 mm) |
||||||||||
Figure 6
Figure 7
Figure 8
Analysis of the data obtained allowed us to identify the following patterns: the smallest values rp take along the line of action of the concentrated force P together with its direct application =270 . At some values of the angle 295 for n=1.34 and 188 for n=1.19 the values of rp change sign. Compressive stresses turn into tensile stresses, tending to break the solidity of the connection. Consequently, the diagrams rp can have a certain physical interpretation: the contact points at which the stress signs change determine the areas of the joint opening zone in the absence of contact pressure from tension due to the elastic deformation of the bandage.
The thinner the bandage, the greater the maximum increase in rp at =270 and the greater the stress gradient in the region =260 280.
The thicker the bandage, the greater the tensile stress, but their gradient is insignificant, that is, the thinner the bandage, the greater the compression force on the axis.
The diagrams of tangential stresses in the zone of action of force P show that p are tensile, and their maximum value is practically independent of the thickness of the bandage. The stress gradient increases with decreasing bandage thickness, and the width of the zone decreases. On most of the contact surface of the axle and the bandage, the stresses are compressive with a smaller gradient for n=1.34.
The diagrams of tangential stresses r in Figure 9 change sign at points at 215 and on most of the contact surfaces they are tensile, but small for both cases, and, therefore, not too significant.
Table 3 presents the values of r and for various values of and n.
Table 3 – The magnitude of contact pressure and tangential stress from interference.
Based on the data in Tables 2 and 3, we will construct diagrams for rp r and the resulting r in accordance with Figure 9. Tangential stresses from tension are different in sign for the contact stresses of the axle and bandage, so consideration of the total diagrams on these surfaces must be done separately (Figure 10, 11).
The analysis of stresses at the axle-tire contact of a composite roll shows that for any load pattern, the total diagram of the contact pressure differs significantly from the diagram of the pressure caused by interference. Contact pressures are distributed evenly around the circumference and have a high gradient in zones of disturbance from metal pressure forces on the roll. In this case, the contact pressures from the interference constitute only a part of the total contact pressure (in accordance with Figure 9) over a significant part of the contact. On part of the contact surface, the total pressure is slightly less than the tension pressure.
MPR [Mkr] = P f R (19)
where Mpr is the rolling moment;
Figure 9
Figure 10 – Diagrams p, , on the contact surface of the axis of the support roll of the mill 2500 at P = 1200 kg/mm; n=1.19; n=1.34 and =0.8; 1.15; 1.3
Figure 11 – Diagrams р, , on the contact surface of the support roll bandage of mill 2500 at Р=1200kg/mm; n=1.19; n=1.34 and =0.8; 1.15; 1.3
a significant part of the contact. On part of the contact surface, the total pressure is slightly less than the tension pressure.
Calculation of the roll for the possibility of turning the bandage on the axis due to the action of torque is carried out according to the formula:
MPR [Mkr] = P f R (19)
where Mpr is the rolling moment;
[Mkr] – torque that the connection can transmit with interference;
P – contact pressure in the connection;
f – coefficient of static friction on the seating surfaces of the connection;
R – radius of the landing surface.
The permissible torque is directly proportional to the contact pressure; therefore, when calculating a composite roll for the possibility of turning the band, it is necessary to take into account the distribution features and the magnitude of the contact pressure in the rolls.
The total contact pressure in a composite roll is determined by the formula:
P= r = rp + r
By integrating r in a circle, we can determine the maximum torque that a composite roll can transmit, taking into account the action of external forces P:
Calculations made using this formula showed that the increase in the maximum torque that a composite roll can transmit without turning the band, taking into account the influence of external forces P, is approximately 20-25%.
The transmitted torque is proportional to the friction coefficient f. The deformation of the roll under load also depends on the value of the friction coefficient. Obviously, to prevent deformation and microdisplacements at the points of contact, it is possible to increase the friction coefficient and create the required specific pressure at the contact. Changing the contact pressure can be achieved by changing the amount of tension and changing the thickness of the bandage. As can be seen from Figures 6, 7, 8, a decrease in the thickness of the bandage leads to an increase in stress gradients at the places where the load is applied. And an increase in interference, in turn, leads to an increase in the stresses themselves, which already at a value of =1.15 for d 2 =1150 mm and =1.3 for d 2 =1300 mm exceed the permissible values for steel 150ХНМ, equal to 200 MPa (Table 1), from which it is proposed to make a bandage.
Therefore, it becomes obvious to increase the coefficient of friction on the seating surfaces. The optimal choice of values for the tension and friction coefficient will avoid surface wear, which will facilitate the repeated use of the axle.
2.3 Calculation for the frequency of use of the axis of a composite support roll
The axles of banded support rolls are made from decommissioned, already used rolls. Therefore, the calculation for the frequency of use of the axle is based on the fatigue strength of its material - 9HF steel.
The calculations took into account the number of loading cycles, the fatigue characteristics of the axle material, as well as the values of 3 types of stresses:
1 – compressive, caused by the fit of the bandage on the axis with tension;
2 – bending, caused by metal pressure on the rolls;
3 – tangents caused by torsion.
The calculation was carried out for the most dangerous sections 1-1 and 2-2 (Figure 12) with different values of the fit interference.
The back-up roll 1600x2500 is transshipped in 5 and 6 stands every 150 thousand tons of rolled products. When sanding, remove from the surface
Figure 12 – Schematic representation of the sections for which the roll axis was calculated for fatigue strength.
– cross section of the middle of the roll barrel
2-2 – section, at the point of transition from the roll barrel to the neck.
barrels are produced with a diameter of at least 3 mm. The total removal is 120 mm ( max = 1600 mm, min = 1080 mm), that is, the roll can be installed at least 40 times, for example, 20 in each stand
The main technological characteristics of the 5th and 6th stands of the finishing group of the 2500 hot rolling mill of OJSC MMK are given in Table 4.
Table 4 – Main characteristics of stands 5, 6
In the calculations we take the average rolling diameter of the support roll d av = 1540 mm.
The metal pressure on the rolls is constant, therefore, the maximum bending stresses bend max are equal to bend min, taken with the opposite sign. The compression stresses сж (Table 1), depending on the magnitude of the interference, are also constant.
Calculations were made for three different interference values =0.8; 1.15; 1.3.
Thus, cyclic loading in all cages, combining the action of constant and variable loads, is asymmetrical in nature.
The number of loading cycles in each cage is:
where V i is the rolling speed in each stand, m/s;
d av – average rolling diameter of the support roll barrel, m;
t is the operating time of the roll in each stand per installation, h;
K – number of installations.
The calculation results are summarized in Table 5.
Table 5 – Number of operating hours and loading cycles in each cage
The total number of loading cycles of the support roll when using the axis once is: N= N i =5.14x10 6 .
2.4 Determination of cyclic endurance in section 1-1
Maximum bending stress:
(23)
where P = 3000 tf – metal pressure on the rolls;
a = 3.27 m – distance between the axes of the pressure screws;
W bend = d 2 axis /32 – moment of resistance of the section during bending;
L barrel =2.5 m – length of the support roll barrel.
The maximum compressive stresses compress are found according to formula (7). Therefore, we have:
G 
de - coefficient of sensitivity of the metal to cycle asymmetry;
0 =(1.4…1.6) -1 - fatigue limit for the pulsating cycle.
The maximum stress caused by torsion maxi in each stand depends on the maximum torque M cr i = 217 tm:
Equivalent stress, taking into account all types of stresses acting on the composite roll:
The calculation results are summarized in Table 6.
Table 6 – Stress values in the roll for various values of landing diameters and interferences
The corresponding number of cycles that the sample can withstand before failure is:
The axle material is 9HF steel, with the following fatigue characteristics:
-1 =317 MPa – endurance limit;
N 0 =10 6 – base number of cycles;
R=tg =(0.276 -1 -0.8)=7.95 kg/mm 2 – slope of the fatigue curve
To assess the durability margin and service life of a part when calculating for limited durability, the n additional duty criterion is used. – permissible durability margin:
where n additional =1.5 – permissible safety factor.
Multiplicity of axle use with full use of the strength properties of the material:
The calculation results are summarized in Table 7.
Table 7 - Influence of the bore diameter and axle tension on its multiplicity
Based on the calculations, the following conclusions can be drawn: with increasing tension, the frequency of use of the axis of the composite support roll is reduced due to an increase in constant compressive stresses caused by the hot fit of the band on the axis with interference. In the case of a thinner band (d=1.13 m), there is an increase in the frequency of use of the axle by more than 3 times at the same tension values, since d=1.13 m is characterized by lower axle compression stresses. If we turn to the stress distribution diagrams for different thicknesses of the bandage (Figure 6, 7, 8, 9, 10, 11), then we should note a less favorable picture for a thinner bandage. It should also be taken into account that the calculations took into account not just the maximum permissible loads on the roll, but their peak values. If we take into account that for steel 150ХНМ, from which it is proposed to make the bandage, the tensile stresses in the bandage exceed the permissible ones in the cases of d = 1.15 m at = 1.15 mm and d = 1.3 m at = 1.3 mm (Table .1), then the option with d=1.15 m, =0.8 can be considered optimal. The axis multiplicity in this case is 2.45 times. But, taking into account that the actual loads are somewhat less than the calculated ones, and also that it is proposed to apply a metal coating to the mating surfaces, which increases the load-bearing capacity of the connection without significantly changing its stress state, the frequency of use of the axis will naturally increase.
2.5 Determination of cyclic endurance in section 2-2
The axis of the support composite roll in section 2-2 experiences bending and tangential stresses. Under such loading, the stresses change in a symmetrical cycle:
There is no danger of fatigue failure of the axle in this section.
2.6 Determination of the slip and deflection zone of a composite and solid support roll
It is a known fact that during work, as a result of the action of applied loads, both the working and support rolls begin to bend. The phenomenon of deflection can cause deterioration in the quality of the rolled strip, runout of the rolls, which, in turn, can lead to rapid failure of bearing units and the appearance of fretting corrosion.
The temperature difference between the band and the axle during the rolling process, in the case of a composite roll, can lead to rotation of the band relative to the axis, that is, the appearance of a slip zone.
Below are calculations of the possible size of the slip zone taking into account the existing loads and determining the deflection of a composite and solid support roll in order to compare their values.
2.7 Determination of deflection of a solid support roll
The metal pressure on the rolls during rolling is transmitted through the work rolls to the support rolls. The nature of the pressure distribution along the barrel of the support rolls depends on the width of the roll, the rigidity and length of the barrel of the working and support rolls, as well as on their profile.
If we assume that the metal pressure on the rolls is transmitted uniformly by the work roll to the support roll, then the deflection of the support rolls can be calculated as the bending of a beam freely lying on two supports, taking into account the action of transverse forces.
Overall support roll deflection:
f o.v. = f He. = f 1 + f 2 (32)
where f 1 – deflection due to bending moments;
f 2 - deflection arrow from the action of transverse forces.
In its turn
where P is the metal pressure on the roll;
E – modulus of elasticity of the roll metal;
G – shear modulus of the roll metal;
D 0 – diameter of the support roll;
d 0 – diameter of the support roll neck;
L – length of the support roll barrel;
a 1 – distance between the axes of the support roller bearings;
c – distance from the edge of the barrel to the axis of the support roller bearing.
Table 8 - Data for calculating the deflection of a solid support roll
|
Continuation of table 8 |
||
Then the total deflection of the support roll is:
f=0.30622+0.16769=0.47391 mm
2.8 Determination of deflection and slip zone for a composite support roll
Basic data for the calculation are given in Table 9.
Table 9 – data for calculating the rigidity of a composite support roll
|
Coefficient taking into account the uneven distribution of shear stresses |
||
|
Continuation of table 9 |
||
Cross-sectional area of the bandage and axle:
Moments of inertia of the bandage and axle:
Constant coefficient:
Contact pressure P H =32.32x10 6 N/m 2 (see Table 1).
Bending moment per unit length arising due to friction forces:
m = 4 P H R 2 = 12822960 Nm (39)
Calculation of the length of the area where the bandage slips relative to the axis during bending:
Let us determine the deflection of the composite support roll using the methodology given in the work. The design diagram is shown in Figure 13.
Figure 13 – Diagram of the acting forces in the axial section of the banded roll
R 
distributed load:
Bending moment acting on the roll in section:
Shearing force acting on the roll in section:
Q 0 = q 0 (l 0 - l) = 10,23 x10 6 N (45)
Determination of deflection at [x=0]:
Angle of rotation at [x=0]:
Intensity of the interaction force between the axle and the bandage:
Determination of deflections for the bandage and axle in the slipping area:
Angles of rotation of the bandage and axle:
Bending moment on the bandage and axle:
Shearing force acting on the band and axle:
Shift of the band relative to the axis at the edge of the roll barrel:
(60)
Roll neck deflection:
(62)
Full deflection of the banded roll:
y= y x + y w = 0.000622 m = 0.622 mm(65)
As can be seen from the calculation results, the deflections of composite and solid rolls under load are almost the same. The deflection of a composite roll is slightly greater than the deflection of a solid one (y solid = 0.474 mm, y composite = 0.622 mm). This suggests that the rigidity of the composite roll is lower, as a result of which the band can slide relative to the axis. Calculations, in turn, showed that the slip zone is small and amounts to only 0.045 m. The size of the slip zone and the rigidity of the roll as a whole are affected by the circumferential tensile stresses in the sleeve t (in accordance with Figure 13).
Experiments carried out to study the rigidity of composite rolling rolls made it possible to see that the highest tensile stresses t are located on the inner contour of the bandage in the area of its contact with the shaft; this indicates an increase in contact pressures from landing when the roll bends. It has been established that a decrease in the relative interference reduces the voltage t. Consequently, by reducing the tension of the press connection, it is possible to eliminate the destruction of the bandage, however, this leads to a loss of shaft rigidity, weakens the press connection, expands the area of the bandage slipping and promotes fretting corrosion of the seating surface. Since the minimum value of interference was chosen for the calculations ( = 0.8 mm), to improve the adhesion of the shaft to the bandage, it is necessary to increase the coefficient of friction on the seating surface, for example, by applying a metal coating.
2.9 Development of measures to prevent fretting - corrosion on sedimentary surfaces and increasing the surface of the roll
Fretting - corrosion - damage to a metal surface as a result of contact friction, in which separated particles and surface layers interact with environmental components (most often oxygen).
It is known that with the slightest loads on contacting surfaces, noticeable damage to the surface layers from fretting can occur. This fully applies to composite rolling rolls assembled using an interference fit, in which contact pressures reach significant values and there are slip zones adjacent to the ends of the band. At the junction points, with alternating displacements of the seating surfaces of the axle and the tire, scuffs are formed, the number of which increases almost proportionally to the tension. Subsequently, they become stress concentrators, which causes accelerated fatigue failure of the axis located at some distance from the end of the bandage along the seating surface. As a rule, in roll designs where fretting corrosion is pronounced, destruction occurs here, and not along the neck. In order to reduce the influence of this process at the ends of the axle, destructive chamfers are made in order to increase the reliability of the axle by removing stress concentrators, which become zero at the mating edge (Figure 14).
Figure 14 – Bevels on the edge of the axis of the banded roll
However, without special types of processing of the seating surfaces, it is not possible to avoid axle failures for this reason. In this case, soft galvanic coatings are most effective. Their use significantly increases the area of actual mating contact. In this case, strong bonds arise in the contact of the mating parts (metal bonding), due to which the metal surfaces of the mating parts are protected from scuffing and mechanical damage. At the same time, the likelihood of the formation of residual deflection sharply decreases, and the prerequisites for repeated use of the axle with replaceable tires increase.
2.10 Study of the influence of mating coatings on the load-bearing capacity of the axle-tire connection. Selection of material and coating technology.
The load-bearing capacity of an interference fit connection is directly proportional to the coefficient of friction on the seating surface, which is included in the basic calculation formulas for determining the highest torques and axial force. The friction coefficient depends on many factors: the pressure on the contact surfaces, the size and profile of microroughnesses, the material and condition of the mating surfaces, as well as the assembly method. It should be noted that for large diameters (d=500 - 1000 mm) of seating surfaces and, accordingly, interferences (up to 0.001 d), which are characteristic of the design of composite rolls, there are no experimental data on the magnitude of friction coefficients. Usually, when calculating composite rolls, the assembly of which is carried out by heating the band to 300-400 C, the friction coefficient is taken equal to f = 0.14. Such caution and the choice of a very low friction coefficient are fully justified. The fact is that at large values of interference (up to 1 - 1.3 mm), the influence of the initial surface roughness and the oxide films formed on it when the bandage is heated, increasing the friction coefficient, may be very insignificant.
A number of works indicate that the load-bearing capacity of tension joints can be significantly increased by applying galvanic coatings to one of the seating surfaces. The thickness of the coatings is usually 0.01 - 0.02 mm. On average, the use of coatings increases friction coefficients by one and a half to four times for all assembly methods.
The increase in the strength of connections with galvanic coatings is explained by the appearance of metallic bonds in the contact zone and an increase in the actual contact area. It was revealed that soft galvanic coatings, even in the region of low pressures, are subject to plastic deformation and will fill the depressions in the microprofile of the covered part without causing plastic deformation. The increase in the strength of the joints is caused by the fact that at the initial moment of displacement of the parts, a simultaneous cutting of a large number of microvolumes of the coating with irregularities of the covered part occurs. The most favorable effect on the load-bearing capacity of cylindrical joints with interference is exerted by soft (anodic) coatings (zinc, cadmium, etc.). They help not only increase the strength of the joints, but also the fatigue resistance of the shafts. Application of zinc coating increases the endurance limit of shafts during circular bending by 20%.
When coatings are applied, the tension in the joint increases. Typically, the increment in interference is taken equal to twice the thickness of the coating, regardless of its type. It should be noted that with large interferences and large diameters of the connection, the influence of the coating thickness is not so significant.
An analysis of the results of works that examine the effect of coatings on the load-bearing capacity of interference joints gives reason to believe that a coating made of sufficiently ductile metals is most suitable for composite rolls. Applying such coatings to the seating surface of the axle allows you to increase the friction coefficient by at least 2 times. When choosing a coating method and technology, we will be guided by the following considerations.
There are various methods of applying metal coatings to prevent corrosion, high temperature, reduce wear, etc. Almost all coating methods (hot, electrolytic, spraying, chemical deposition, etc.) require surface preparation, usually including degreasing, etching , chemical and electrochemical polishing. These operations are harmful to operating personnel and, despite careful wastewater treatment, pollute the environment.
Using the above methods to coat the axle of a composite mill roll about 5 meters long presents significant technical difficulties. It should be noted that in works that provide data on the effect of coatings on the coefficient of friction, coatings were applied electrolytically or hot to small samples or models of rolling rolls. The use of such methods for large-sized rolls will require the creation of special departments or workshops. It seems appropriate to use friction coating methods. One of the simplest and most effective is the method of applying a coating with a rotating metal brush (VMShch, friction cladding). In this case, simultaneously with the application of the coating, surface plastic deformation (SPD) occurs, which will help increase the fatigue strength of the roll axis.
A diagram of one of the options for applying a coating with a rotating metal brush is shown in Figure 14.
The coating material (MP) is pressed against the pile of the VMSh and is heated in the contact zone with it to a high temperature. Particles of the coating metal are attached to the ends of the fibers and transferred to the surface to be treated. The surface of the workpiece is strengthened due to intense plastic deformation by flexible elastic elements. At the same time, plastic deformation of the coating metal particles located at the ends of the fibers occurs and they adhere to the surface of the product. Removal of oxide films, exposure of clean surfaces with joint plastic deformation of the surface layers and particles of the coating material ensures their strong adhesion to the base.
Figure 14 – Scheme of coating application by friction cladding (FP)
blank of coating material (MP)
tool with flexible elastic elements (VMS)
workpiece (axis of compound roll)
The coating that is applied to the seating surface of the axis of the rolling roll must have the following properties: significantly increase the coefficient of friction, be sufficiently plastic and fill the cavities of the microprofile, and have good thermal conductivity. Aluminum can meet these requirements. It is well applied to a steel surface using a VMSh and forms a coating of sufficient thickness. However, the answer to the main question - about the value of the friction coefficient in a connection with an interference fit, one of the mating surfaces of which is coated with aluminum - is missing in the technical literature. Cylindrical joints made of steel - aluminum materials, assembled using an interference fit, are also not known, since pure aluminum is not used as a structural material due to its low strength characteristics. However, there is data on friction coefficients during plastic deformation of metals (Table 10).
Table 10 - Coefficients of dry friction of various metals on steel grade EKh-12 with hardness HB-650
As follows from Table 10, aluminum under conditions of plastic deformation has a maximum coefficient of friction in contact with the rest of the surface. In addition, aluminum has very high thermal conductivity. These factors were the reason for choosing aluminum as the coating material for the male surface of the roll axis.
2.11 Selection of axle and tire material and methods of heat treatment
When choosing the material for composite rolls, the thermomechanical conditions of their service should be taken into account. Rolls are subjected to significant static and impact loads, as well as thermal effects. Under such harsh operating conditions, it is very difficult to select a material that simultaneously provides high strength and wear resistance.
There are different requirements for the roll barrel and its core. The core must have sufficient viscosity and strength, and be able to resist bending, torque and impact loads well. The surface of the barrel must have sufficient hardness, wear resistance, and heat resistance.
The roll axis is made of 9ХФ steel, the roll band is 150ХНМ, based on the experience of using this steel in the manufacture of composite roll bands at OJSC MMK. It is proposed to use a more alloyed steel as the bandage material - 35Х5НМФ, which has higher wear resistance in comparison with 150ХНМ. Data on the wear resistance of roll materials under hot rolling conditions are presented in Table 11.
Table 11 - Mechanical properties and wear resistance of roll materials.
|
Steel grade |
Approximate chemical composition |
Mechanical properties |
Relative wear resistance |
||
It follows from the table that steels 60ХН and 9ХН, which are used mainly for vertical and horizontal rolls of the roughing group, have the lowest relative wear resistance, which is confirmed by the experience of their operation. But these steels, according to their characteristics, are quite suitable for the manufacture of axes of composite rolls. For the manufacture of cast bandages, it seems advisable to use steel 150ХНМ 35Х5НМФ.
35Х5НМФ has a higher cost compared to 150ХНМ, but, having significant strength and wear resistance, it justifies itself during operation, since, providing increased resistance to wear and chipping, it retains the good surface structure of the roll barrel longer.
To give the tires and axles the necessary performance properties, they are first separately heat treated. Then the bandage, heated to a certain temperature, ensuring sufficiently free fitting onto the profiled axle, is formed into a press fit (during cooling, the axle is enclosed).
These technological operations lead to the formation of significant residual stresses in the bandage from heat treatment. There are known cases where, due to the high level of these stresses, the bandages were destroyed even before use: during storage or transportation.
According to operating conditions, the axles are not subject to high hardness requirements (230 280HB), while the requirements for tires are more stringent (55 88HSD). In this regard, a milder heat treatment is used for the axles compared to tires, which does not lead to the occurrence of significant residual stresses. In addition, tensile stresses from fit, which are dangerous from the point of view of brittle strength, arise only in the bandage, as a result of which a fracture can occur along the roll barrel.
As the experience of heat treatment of these steels in the manufacture of bandages shows, the most effective treatment is triple normalization with temperatures of 1050 C, 850 C and 900 C followed by tempering, providing the most favorable combination of plastic and strength characteristics.
Triple normalization results in the preservation of the heritage cast structure and promotes distribution of properties that provide increased resistance to wear and chipping.
The roll axis is made from a waste roll. After grinding to the required dimensions, an aluminum coating approximately 20-25 microns thick is applied to the seating surface of the axle using the friction method. The final treatment of the seating surface before coating is clean grinding.
Thermal assembly significantly (on average 1.2-1.5 times) increases the load-bearing capacity of interference joints. This is explained by the fact that during assembly under pressure the micro-irregularities are crushed, while during thermal assembly they close into each other, which increases the coefficient of friction and adhesion strength. In this case, the coating particles penetrate both the surface of the axle and the tire, and mutual diffusion of atoms of the coating and the base metal occurs, which makes the connection almost monolithic.
Therefore, in the connection it is possible to reduce the interference required to transmit a given torque, with a corresponding reduction in stresses in the axle and bandage.
If the bandage is heated sufficiently high, it is possible to obtain zero interference or provide a gap when assembling the connection. The recommended temperature for heating the bandage before assembling the roll is 380 C-400 C.
The following methods for replacing worn bandages are possible:
Mechanical - along the generatrix of the bandage along its entire thickness, two slots are made on a planing or milling machine, as a result of which the bandage is divided into two halves, which are easily dismantled. The slots are located diametrically opposite to one another.
Heating of the bandage in the inductor by industrial frequency currents (IFC) - the bandage is heated to 400 C-450 C. This temperature is achieved in three or four transitions of the inductor within 15-20 minutes. When the bandage is heated across its cross-section to the specified temperature, it falls off the seating surface.
Dismantling the bandage using an explosion - this technology was used at MMK back in the 50s of the last century. In 1953, the 1450 hot rolling mill was completely converted to composite back-up rolls. Worn tires are removed from the axle by the explosion of small charges placed in drilled holes. This technology is possible in the conditions of Magnitogorsk.
Economic justification for the project
OJSC MMK is the largest metallurgical plant in our country. Its main task is to fully satisfy the market needs for high-quality products. Shop LPC-4 is part of MMK, which is a joint-stock company. The development of the plant does not stand still: metal processing methods are being improved, new ideas are being implemented, and modern equipment is being purchased.
The modernization of mill 2500 LPC-4 of OJSC MMK is carried out by replacing solid rolls with banded ones. The cost of one banded roll is 1.8 million rubles, while the annual consumption of rolls is 10 pcs. The cost of banded rolls is 60% of the cost of solid ones, and due to the use of more wear-resistant material for the band, the annual consumption of rolls will decrease by 1.6 times and amount to 6 pcs. in year.
4.1 Calculation of the production program
Drawing up a production program begins with calculating the balance of equipment operating time in the planned period 28.
The actual operating time of the equipment is calculated using the formula:
T f =T nom *S*T With *(1-T etc. /100%) (66)
where C=2 – number of equipment operation shifts,
Т с =12 – duration of one shift,
Т t.pr – percentage of current downtime in relation to the nominal time (8.10%),
T nom – nominal operating time of the equipment, calculated by the formula:
T nom =T feces -T rp -T p.pr -T V (67)
where T cal = 365 days. – calendar fund of equipment operating time,
T rp = 18.8 days. – regime downtime;
T p.pr = 12 - number of days the equipment is undergoing scheduled maintenance,
T in – the total number of holidays and weekends in a year.
T in =0, since the work schedule is continuous.
The annual production volume is calculated as:
Q year =P Wed *T f (68)
Where P av = 136.06 t/hour – average hourly productivity.
Actual operating time of the equipment and annual production volume:
T no =365-18.8-12-0=334.2 (days)
T t.pr =0.081*334.2=27.7 (days) or 650 (hours)
T f =334.2*2*12*(1-8.1/100)=7371 (h)
Q year =136.06*5033=1002870 t
The calculated data are shown in Table 12.
Table 12 - Equipment operating time balance
4.2 Calculation of capital cost estimates
The costs of modernizing mill 2500 are calculated using the formula:
TO h =C about +M+D±O-L(69)
where M is the cost of installing equipment,
D – costs of equipment dismantling,
О – residual value of dismantled equipment
L – liquidation value (at the price of scrap metal), calculated as:
L=m*C l (70)
where m is the mass of the dismantled equipment,
Ts l – price of 1 ton of scrap metal,
C ob – cost of purchased equipment.
Then the cost of purchasing rolls will be:
With rev =6*(1800000*0.6)=6480000 rub.
The costs of dismantling old and installing new rolls are zero, since changing rolls is the current work in the workshop: M=D=0 rub.
Solid rolls are being replaced, which are already worn out, and accordingly their residual value is O = 0 rub.
Worn-out solid rolls are recycled and therefore have no salvage value (L = 0).
Thus, capital costs for modernization:
To z =6480000+0+0+0-0=6480000 rub.
4.3 Organization of labor and wages
The calculation of the wage fund is shown in Table 13.
Table 13 - Calculation of the wage fund
|
Indicator name |
Worker's name |
||||||||
|
Brigadier |
Roller |
Post operator |
|||||||
|
|
|||||||||
Continuation of table 13 |
|||||||||
Explanations for Table 13:
Calculation of working time fund (clause 9):
t months =365*С shifts * t shifts /(12*b) (71)
where C shifts =2 – number of shifts per day,
t shifts = 12 hours – duration of one shift,
b=4 – number of teams,
t months =365*2*12/(12*4)=182.5 person*hour
Working hours on holidays:
t etc =n etc * WITH shifts * t shifts /(12*b) (72)
t pr =11*2*12/12*4=5.5 person*hour
Scheduled processing time:
∆ t month =t gr -(2004/12),
t gr =∆ t month -t pr.
∆ t month =182.5-2004/12=15.5 person*hour,
t gr =15.5-5.5=10 person*hour.
Calculation of operating hours at night and evening:
t night =1/3* t month,
t evening =1/3* t month,
t night =1/3*182.5=60.83 person*hour,
t evening =1/3*182.5=60.83 person*hour.
Calculation of wages according to the tariff (clause 10.1):
Salary tar = t hour * t month,
t hour – hourly tariff rate.
For the 7th category: salary tar = 24.78 * 182.5 = 4522.35 rubles;
For the 6th category: salary tar = 21.71 * 182.5 = 3962.07 rub.
For the 5th category: salary tar = 18.87 * 182.5 = 3443.78 rub.;
Calculation of piecework earnings (clause 10.2):
∆ZP sd =ZP tar *[(N exp -100)/100], where
N exp - planned fulfillment of production standards, %.
For both workers: ∆ZP sd =0, since the production rate is 100% and there is no break-in.
Calculation of production bonus (clause 10.3):
Salary premium =(Salary tar. + ∆Salary sd)*Premium/100%,
The production bonus established for this area is 40%.
For 7th grade: premium salary. =(4522.35+0)*40%/100%=1808.94 rub.;
For 6th grade: premium salary. =(3962.07+0)*40%/100%=1584.83 rub.
For 5th grade: premium salary. =(3443.78+0)*40%/100%=1377.51 rub.;
Calculation of additional payment for work on holidays with a production rate of 100%:
∆ZP pr = t hour *(100/100)* t pr.
For the 7th category: ∆ZP pr =24.78*5.5=136.29 rub.,
For the 6th category: ∆ZP pr =21.71*5.5=119.41 rub.
For the 5th category: ∆ZP pr =18.87*5.5=103.78 rub.,
Calculation of additional payment for overtime according to schedule (37.5%):
∆ZP gr = t hour *(37.5/100)* t gr
For the 7th category: ∆ZP gr =24.78*10*0.375=92.93 rub.,
For the 6th category: ∆ZP gr =21.71*10*0.375=81.41 rub.
For the 7th category: ∆ZP gr =18.87*10*0.375=70.76 rub.,
Calculation of additional payment for night work (40%):
∆ZP night = t hour *(40/100)* t night
For the 7th category: ∆wage night =24.78*0.4*60.83=602.95 rub.,
For the 6th category: ∆wage night =21.71*0.4*60.83=528.25 rub.
For the 5th category: ∆wage night =18.87*0.4*60.83=459.14 rub.,
Calculation of additional payment for work in the evening (20%):
∆ZP evening = t hour *(20/100)* t evening
For the 7th category: ∆ZP evening =24.78*0.2*60.83=301.47 rub.,
For the 6th category: ∆ZP evening =21.71*0.2*60.83=264.12 rub.
For the 5th category: ∆ZP evening =18.87*0.2*60.83=229.57 rub.,
The regional coefficient for the Ural region is 15%.
∆ZP p =0.15*(ZP tar +∆ZP sd +∆ZP pr +∆ZP gr +∆ZP night +∆ZP evening +ZP prem.).
For the 7th category: ∆ZP p =0.15*(4522.35+0+1808.94+136.29+92.93+
602.95+301.47)=1502.32 rub.,
For the 6th category: ∆ZP p =0.15*(3962.07+0+1584.83+119.41+
81.41+528.25+264.12)=966.01 rub.
For the 5th category: ∆ZP p =0.15*(3443.78+0+1377.51+103.78+70.76+
459.14+229.57)=852.68 rub.,
Calculation of additional wages (clause 11):
When the duration of the next vacation is 30 days, the coefficient of dependence of additional wages on the main one is 17.5%.
For the 7th category: additional salary = 0.175 * 8584.67 = 1502.32 rubles,
For the 6th category: additional salary = 0.175 * 7406.10 = 1296.07 rubles.
For the 5th category: additional salary = 0.175 * 6537.22 = 1144.01 rub.
4.4 Calculation of contributions for social needs
Annual wage fund:
Payroll year = S number *Salary months *12 (73)
where S number is the payroll number,
Salary month – monthly salary of one employee.
Payroll year =(80695.92+69617.36+30724.92+34808.68+30724.92)*12=2958861.6 rub
Table 14 - Calculation of contributions to extra-budgetary funds
Total payroll with deductions: 2958861.6 +1053354.7=34012216.33 rub.
4.5 Calculation of product costs
Table 15 - Cost calculation for 1 ton of finished products
|
Name of cost item |
Price, rub./unit |
Sum |
deviation |
|
Calculations for table 15:
1. Basic salary of production workers:
Salary basic = Salary basic *12* S number / Q year (74)
Salary main = (8584.67*8+7406.10*12+6537.22*8)*12/187946=3.46 rub.
2. Additional pay for production workers:
Salary extra = Salary extra *12* S number / Q year (75)
Additional salary =(1502.32*8+1296.07*12+1144.01*8)*12/187946=0.61 rub.
3. Deductions from the wage fund:
Deductions from the wage fund were calculated in the previous chapter in table. 3 and amount to 2958861.6 rubles. for the entire annual production volume, then per 1 ton they will be: 2958861.6 /186946 = 4.07 rubles.
In the design version, all costing items will remain unchanged, except for the costs of replacement equipment (rolls).
4.6 Calculation of main technical and economic indicators
Profit from product sales:
Pr=(C-S/s)*Qyear (76)
where C is the average wholesale price excluding VAT for 1t of finished products.
Ts=4460 rubles, then with VAT Ts=5262.8 rubles.
in the basic version:
Pr=(4460-4052.85)*1002870=408318520 rub.,
in the design version:
Pr / =(4460-4026.89)*1002870=434353026 rub.
Table 16 - Calculation of net profit
|
The name of indicators |
Amount, rub. |
Deviations |
||
|
Revenue from sales of products, total (Price including VAT*Qyear) |
||||
|
incl. VAT (line 1*0.1525) |
||||
|
Revenue from sales of products net of VAT (line 1-line 2) |
||||
|
Cost of production (С/с*Qyear) |
||||
|
Administrative expenses |
||||
|
Business expenses |
||||
|
Gross profit (pages 2-3-4-5) |
||||
|
Proceeds from the sale of fixed assets and other property |
||||
|
Interest receivable |
||||
|
Revenues by state securities |
||||
|
Income from participation in other organizations |
||||
|
Other non-operating income |
||||
|
Payments for the use of natural resources |
||||
|
Expenses for the sale of fixed assets and other property |
||||
|
Other operating expenses |
||||
|
Percentage to be paid |
||||
|
Property tax |
||||
|
Other non-operating expenses |
||||
|
Profit of the reporting year (Σstr.6ch11 –Σstr12ch18) |
||||
|
Taxable income (line 19-8-9-10) |
||||
|
Income tax (line 20*0.24) |
||||
|
Net profit (page 19-page 21) |
||||
∆Pch=326888666-307102442=19786224 rub.
Product profitability:
Rp=(Pr/S/s)*100% (77)
in the basic version:
Рп=(4460-4052.85)/4052.85*100%=10%,
in the design version:
Rp / =(4460-4026.89)/4026.89*100%=10.75%.
PNP=Pch/I (78)
where I is the total volume of investment.
The total volume of investments is equal to the amount of capital costs (I=Kz=6,480,000 rub.)
PNP=326888666/6480000=50.44.
Payback period:
Current=I/∆Fr (79)
Current=6480000/19786224=0.32 g or 4 months.
Conclusion
It is proposed to replace the use of solid forged back-up rolls in stands 5 and 6 of mill 2500 (LPTs-4) of MMK OJSC with composite rolls.
Based on the review, analysis of designs and operating experience of banded rolls, the optimal design of a composite roll was selected in terms of ease of production and lower cost.
It is proposed to use steel 150ХНМ or 35Х5НМФ as the bandage material, the wear resistance of which is 2-3 times higher than 9ХФ steel, from which solid forged rolls are made. It is proposed to manufacture the bandages cast with triple normalization. To make axles, use waste rolls.
Calculations of the stress-strain state and load-bearing capacity were made for various values of landing diameters ( 1150 mm and 1300 mm), minimum, average and maximum values of interference ( = 0.8; 1.15; 1.3) and friction coefficient ( f=0.14;0.3;0.4). It has been established that in the case of 1150 mm, the stress distribution pattern in the roll is more favorable than for 1300 mm, and the load-bearing capacity is 1.5-2 times higher. But as the interference increases, the tensile stresses in the joint also increase, exceeding those allowed for steel 150ХНМ. Therefore, it becomes advisable to use a minimum tension = 0.8 mm, which ensures transmission of torque with a sufficient margin even with a minimum friction coefficient f = 0.14.
To increase the load-bearing capacity of such a connection without increasing the stress value, it is proposed to increase the coefficient of friction on the mating surfaces by applying a metal coating. Aluminum was chosen as the coating material based on its cost and thermophysical properties. As the experience of using such a coating on the mating surfaces of the axle and tire under the operating conditions of composite rolls at the mill 2000 (LPS-10) of OJSC MMK shows, aluminum increases the coefficient of friction to values f = 0.3-0.4. In addition, the coating increases the area of actual contact between the axle and the bandage and its thermal conductivity.
The maximum possible deflection, determined by calculation, is 0.62 mm, the slip zone is 45 mm.
The connection of the bandage to the axle is carried out thermally, by heating the bandage to 350 -400 C.
Based on the calculations, the selected design of a composite roll with cylindrical seating surfaces of the axle and tire, without the use of any additional fixing devices (collars, cones, keys), was considered optimal.
To prevent fretting corrosion and relieve the concentration of residual stresses at the ends of the bandage, bevels are made at the edges of the axis, so that in the areas adjacent to the ends of the bandage the interference is zero.
The cost of a composite roll is 60% of the cost of a new solid forged roll (1.8 million rubles). With the transition to composite rolls, their consumption will be reduced from 10 to 6 pcs per year. The expected economic effect will be about 20 million rubles.
List of sources used
Useful Maud. 35606 RF, MPK V21V 27/02. Composite rolling roll /Morozov A.A., Takhautdinov R.S., Belevsky L.S. and others (RF) - No. 2003128756/20; application 09/30/2003; publ. 01/27/2004. Bull. No. 3.
Roll with a bandage made of sintered tungsten carbide metal. Kimura Hiroyuki. Japanese patent. 7B 21B 2700. JP 3291143 B2 8155507A, 11/29/94.
Useful Maud. 25857 RF, MPK V21V 27/02. Rolling roll /Veter V.V., Belkin G.A., Samoilov V.I. (RF) - No. 2002112624/20; application 05/13/2002; publ. 10/27/2002. Bull. No. 30.
Pat. 2173228 RF, IPC V21V 27/03. Rolling roll /Veter V.V., Belkin G.A. (RF) - No. 99126744/02; application 12/22/99; publ. 10.09.01//
Pat. 2991648 RF, IPC V21V 27/03. Composite rolling roll /Poletskov P.P., Firkovich A.Yu., Tishin S.V. and others (RF) - No. 2001114313/02; application 05/24/2001; publ. 10/27/2002. Bull. No. 30.
Useful Maud. 12991 RF, MPK V21V 27/02. Composite roll /Poletskov P.P., Firkovich A.Yu., Antipenko A.I. and others (RF) - No. 99118942/20; application 01.09.99; publ. 03/20/2000. Bull. No. 8.
Pat. 2210445 RF, MPK V21V 27/03. Composite roll /Poletskov P.P., Firkovich A.Yu., Antipenko A.I. and others (RF) - No. 2000132306/02; application 12/21/2000; publ. 08/20/2003. Bull. No. 23.
Grechishchev E.S., Ilyashchenko A.A. Interference connections: Calculations, design, manufacturing - M.: Mashinostroenie, 1981 - 247 pp., ill.
Orlov P.I. Fundamentals of design: Reference and methodological manual. In 2 books. Book 2. Ed. P.N. Uchaeva. – 3rd ed., corrected. – M.: Mechanical Engineering, 1988. – 544 p., ill.
Narodetsky M.Z. To the choice of landing rings of rolling bearings. “Engineering collection” Institute of Mechanics of the USSR Academy of Sciences, vol. 3, no. 2, 1947, p. 15-26
Kolbasin G.F. Study of the performance of composite rolling rolls with replaceable tires: Dis.: ..candidate of technical sciences. – Magnitogorsk, 1974. – 176 p.
Timoshenko S.P. Strength of materials, h. P.M. – L., Gostekhteorizdat, 1933.
Balatsky L.T. Fatigue of shafts in joints. – Kyiv: Technology, 1972, - 180 p.
Polukhin P.I., Nikolaev V.A., Polukhin V.P. etc. Strength of rolling rolls. – Alma-Ata: Science, 1984. – 295 p.
Hot rolling of strips on the 2500 mill. Technological instruction TI - 101-P-Ch.4 - 71-97
Calculation of the multiplicity of use of the axis of a composite roll / Firkovich A.Yu., Poletskov P.P., Solganin V.M. – Sat. center. lab. OJSC MMK: issue. 4. Magnitogorsk 2000. – 242 p.
Sokolov L.D., Grebenik V.M., Tylkin M.A. Research of rolling equipment, Metallurgy, 1964.
Sorokin V.G. Brand of steels and alloys, Mechanical Engineering, 1989.
Firsov V.T., Morozov B.A., Sofronov V.I. and others. Study of the performance of press joints of the shaft-bushing type under conditions of static and cyclic alternating loading // Bulletin of Mechanical Engineering, - 1982. No. 11. - With. 29-33.
Safyan M.M. Rolling of broadband steel. Publishing house "Metallurgy", 1969, p. 460.
Tselikov A.I., Smirnov V.V. Rolling mills, Metallurgizdat, 1958.
Firsov V.T., Sofronov V.I., Morozov B.A. Experimental study of rigidity and residual deflection of banded support rolls // Strength and reliability of metallurgical machines: Proceedings of VNIMETMASH. Sat. No. 61. – M., 1979. – p. 37-43
Bobrovnikov G.A. Durability of plantings carried out using cold. – M.: Mashinostroenie, 1971. – 95 p.
Belevsky L.S. Plastic deformation of the surface layer and formation of a coating when applied with a flexible tool. – Magnitogorsk: Lyceum RAS, 1996. – 231 p.
Chertavskikh A.K. Friction and lubrication in metal forming. – M.: Matallurgizdat, 1949
Vorontsov N.M., Zhadan V.T., Shneerov B.Ya. etc. Operation of rolls in crimping and section rolling mills. – M.: Metallurgy, 1973. – 288 p.
Pokrovsky A.M., Peshkovtsev V.G., Zemskov A.A. Assessment of crack resistance of banded rolling rolls // Bulletin of mechanical engineering, 2003. No. 9 – p. 44-48.
Kovalev V.V. Financial analysis: Methods and procedures. – M.: Finance and Statistics, 2002. – 560 p.: ill.
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Essay
Thesis on the topic: “Research and development of the design of a banded support roll of the 2500 hot rolling mill of OJSC MMK.”
72 pages, 14 figures, 16 tables, 28 sources used, 7 sheets of graphic material.
Key words: support roll, bandage, axle, frequency of use of the axle, stress in the composite roll, deflection, slip zone, interference, coating.
Object of research and development: banded support roll.
Purpose of the work: development of the design of composite support rolls, ensuring their reliability during operation, increasing their durability and reducing cost.
Research method: computational and graphical.
The main design, technological and technical-operational characteristics: the seating surfaces of the tire and axle are cylindrical, the fits are carried out with a guaranteed interference fit, without the use of additional fixing devices, with the application of a metal coating to the mating surfaces.
Results obtained: the optimal design dimensions of the roll, tension, and bandage material were selected.
Scope of application: rolling production.
Economic efficiency: expected annual effect is about 20 million rubles.
Faculty___ Mechanical engineering _______
Department____ OD and PM ____________________________
Speciality____ 1204 Mechanical Engineering and Technology __metal forming _____
Allow for protection
Head of the department
_______________/Denisov P.I./
«____»________________ 2004
GRADUATE WORK
_______D.MM.1204.001.00.00.PZ ______
Student Mukhomedova Ekaterina Anyasovna ________________
On the topic of:____ _________ ___ 2500 hot______ ________________ rolling of JSC MMK________________________
Composition of the thesis:
Settlement and explanatory note for _ 72 pages
Graphic part on _ 7 _sheets
CALCULATION AND EXPLANATORY NOTE FOR THE DIPLOMA THESIS
Thesis supervisor________________________________ /Belevsky L.S./
____________
Consultants__ Art. teacher _____________________ ________/Kulikov S.V./
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
(academic degree, academic title, surname, acting)
Graduate______________________
(signature)
"____"______________2004
MINISTRY OF EDUCATION OF THE RUSSIAN FEDERATION
MAGNITOGORSK STATE
TECHNICAL UNIVERSITY named after. G.I. NOSOVA
Department____ OD and PM_ ______________________________
_______________________________________________
I CONFIRM:
Head of the department
_______________/Denisov P.I./
2004
GRADUATE WORK
Subject:_____ Design research and development________ _ ___ banded support roll of the mill 2500 hot______ ________________ rolling of JSC MMK________________________
__________________________________________________________________
Student ______ Mukhomedova Ekaterina Anyasovna _____________________
(Full Name)
The topic was approved by university order No.___________ dated_________________200___.
Completion date "_____"______________________200___g.
Initial data for work:__ - Technological instructions for mill 2500.__________
List of questions to be developed in the thesis: _______________________
1. Analysis of the designs of composite rolling rolls;___________________________
2. _Development of the design of a banded support roll for the hot rolling mill “2500” (selection of structural dimensions of the roll, tension, bandage material);_____
3. Determination of the maximum deflection of a composite roll;______________________
4. Study of the influence of coatings on the load-bearing capacity of the axle-______ bandage connection, choice of material and coating technology;_____________________
5. Development of measures to prevent fretting corrosion;_____________ 6. Development of measures to replace used bandages;________________ 7. Assessment of the economic effect of the project implementation;______________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
The grafical part: 1. Composite support roll 5,6 stands of mill 2500 OJSC MMK____
2. Characteristics of rolling rolls 5 and 6 stands of mill 2500______________________
3. Calculation scheme for determining the stress state of the roll_____________
4.Calculation formulas for determining the stress state of the roll___________
5. Stress diagrams depending on contact pressure______________________
6. Diagrams of tangential stresses on the contact surfaces of the axle and tire__
7. Technical and economic indicators_____________________________________________
________________________________________________________________________
Work consultants (indicating the sections related to them):
Kulikov S.V. – Economics and planning__________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Supervisor:_________________________________________/_ Belevsky L.S. ____/
(signature, date)
Received the task:_______________________________________________/__ Mukhomedova E.A.___/
1.1 Continuous mill 2500 of the Magnitogorsk Iron and Steel Works
The workshop was put into operation in 1968. The mill equipment is located in seven bays (Figure 1).
Figure 1. Main diagram technological equipment Mill 2500 of the Magnitogorsk Iron and Steel Works:
I - hot-rolled coil warehouse span, II - NTA span, III - mill span, IV - bell furnace span; 1 - hot-rolled coil transfer conveyor, 2 - overhead cranes, 3 - continuous pickling units, 4 - cross-cutting unit for hot-rolled coils, 5 - mill working line, 6 - skin tempering mill, 7 - skin tempering mill 1700, 8 and 9 - longitudinal units and cross cutting, 10 - bell furnaces.
The mill is designed for cold rolling of strips with a cross section of (0.6-2.5) x (1250-2350) mm h? 30-roll internal diameter 800 mm, external? 1950 mm from steels 08Yu, 08kp, 08ps (GOST 9045-80), steels 08 - 25 of all degrees of deoxidation with chemical composition according to GOST 1050-74 and St0 - St3 boiling, semi-calm and calm (GOST 380-71).
Hydraulic calculation of the combined external water supply of an industrial enterprise
No. Name 1 Water intakes 2 Gravity lines 3 Coastal well 4 Pumping station of the 1st lift 5 Treatment facilities 6 Clean water reservoir 7 Pumping station of the 2nd...
Use of systems and means of automation of technological facilities at the OJSC MMK enterprise
Production at MMK begins with an ore processing plant (ore processing) and a sinter plant (producing sinter by finely agglomerating ore material, which is necessary for smelting cast iron). Next comes coke production...
Complex of mechanical equipment for sintering production
1. The following are used as iron-containing additives: - flue dust from blast furnace shops; - burnt scale PGP, KTs-1...
System modernization automatic control and flocculant dosing unit, design development of a flocculant flow measurement unit
Biological wastewater treatment plants OJSC "Svetogorsk" represents a classic scheme (Figure 2.1.1) using primary settling tanks, aeration tanks with activated sludge, followed by sludge separation in secondary settling tanks...
Application of technology for vacuum drying of the surface of cold-rolled strip to remove cutting fluids in the conditions of mill 2500 LPC-5 of OJSC MMK
I - annealing department, II - mill bay, III - machine room, IV - finished product warehouse; 1 - overhead cranes, 2 - annealing furnaces, 3 - tilters, 4 - electrolytic cleaning unit, 5 - unwinder, 6 - mill line, 7 - winder, 8 - cutting unit...
Development of a technological process for the production of sheets using the cold rolling method
The mill, put into operation in 1956, is located in eight bays (Fig. 1) with a total width of 195 m and a length of 456 m. I - annealing department, II - mill bay, III - machine room, IV - finished product warehouse; 1 - overhead cranes, 2 - annealing furnaces, 3 - tilters...
Table 2 Characteristics of the NM 2500-230 pump when operating on water Q H 3 N 300 250 0.28 820 500 248 0.4 850 700 246 0.51 900 900 244 0.61 1000 1100 240 0.7 1050 1300 2 38 0.77 1100 1500 235 0.81 1200 1700 230 0...
Calculation and regulation of operating modes centrifugal pump
Table 4- The characteristics of the pump NPV 2500-80 when working on water Q h h N 300 80 0.22 300 500 80 0.35 320 700 78 0.48 350 900 78 0.52 380 1100 77 0.65 400 1300 75 0, 7 430 1500 72 0.75 450 1700 68 0...
Adjustment of strip thickness and tension in the mill entry zone
To measure the strip tension in each inter-stand space, a single-roller tension meter is installed on the cold rolling mill 2500, which uses a magnetically anisotropic pressure sensor DM-5806 designed by VNIIAChermet...
System of extraction, preparation and enrichment of raw materials for ferrous and non-ferrous metallurgy
In addition to the marketable products obtained from the processing of non-ferrous metal ores, non-ferrous metallurgy enterprises produce numerous wastes and intermediate products of metallurgical production. These include slag, dust, gases...
Cold rolling mills
The first stage of the cold rolling shop was put into operation in 1963, the mill equipment is located in 12 bays (Figure 2). Figure 2...
Cold rolling mills
Of the mills considered, the most suitable is the Continuous Mill 2030. The continuous five-stand cold rolling mill 2030 is designed for rolling strips with a thickness of 0.35-2.0 mm in an endless mode and 0.35-3...
The structure of modern metallurgical production and its products. Milling methods and types of cutters used
Ferrous metals are used in various fields of industry: heavy engineering, machine tool building, shipbuilding, automotive industry, aviation industry, electronics, radio engineering, industrial and civil construction...
Shops of the metallurgical plant named after. Ilyich
All metallurgical plants are divided into: those with a full (or complete) production cycle and plants with an incomplete metallurgical cycle. MMK im. Ilyich - a plant with a complete metallurgical cycle...
Introduction
The bulk of the steel produced passes through rolling shops and only a small amount through foundries and forges. Therefore, much attention is paid to the development of rolling production.
The course “Technological lines and complexes of metallurgical shops” is a special discipline that develops students’ professional knowledge in the field of theory and technology of continuous metallurgical lines and units.
As a result of execution course work The following sections must be completed:
Develop and describe technological processes in general for sections (units) and for individual operations with elaboration of issues of technology continuity;
Make a choice according to the specified performance and size cross section sheet products from a cold sheet rolling mill, from existing structures;
Calculate the distribution of reductions along the passes in the rolling mill stands;
Perform calculations of rolling forces in each stand of the rolling mill and the power of electric drives;
Determine the annual productivity of the mill;
Automate the technological modes of compression.
In the course of course work, the knowledge gained from studying the TLKMC course is consolidated and expanded, skills appear in the selection of production equipment, calculations of technological modes of reduction and power parameters of rolling, and the use of electronic computers in calculations.
Cold rolling mills
By cold rolling, tapes, sheets and strips of the smallest thickness and width up to 4600...5000 mm are obtained.
The main parameters of broadband mills are the barrel length of the working stand (in continuous mills of the last stand).
For the production of cold-rolled steel sheets, reversible single-stand and sequential multi-stand mills are used.
According to the task, the most suitable are 3 camps:
Continuous mill 2500 of Magnitogorsk Iron and Steel Works
The workshop was put into operation in 1968. The mill equipment is located in seven bays (Figure 1).
Figure 1. Diagram of the main technological equipment of mill 2500 of the Magnitogorsk Iron and Steel Works:
I - hot-rolled coil warehouse span, II - NTA span, III - mill span, IV - bell furnace span; 1 - hot-rolled coil transfer conveyor, 2 - overhead cranes, 3 - continuous pickling units, 4 - cross-cutting unit for hot-rolled coils, 5 - mill working line, 6 - skin tempering mill, 7 - skin tempering mill 1700, 8 and 9 - longitudinal units and cross cutting, 10 - bell furnaces.
The mill is designed for cold rolling of strips with a cross section of (0.6-2.5) x (1250-2350) mm h? 30-roll internal diameter 800 mm, external? 1950 mm from steels 08Yu, 08kp, 08ps (GOST 9045-80), steels 08 - 25 of all degrees of deoxidation with chemical composition in accordance with GOST 1050-74 and St0 - St3 boiling, semi-calm and calm (GOST 380-71).
Continuous mill 1700 of the Mariupol Metallurgical Plant named after. Ilyich
The first stage of the cold rolling shop was put into operation in 1963, the mill equipment is located in 12 bays (Figure 2).
Figure 2. Layout of the main technological equipment of the cold rolling mill 1700 of the Mariupol Metallurgical Plant named after. Ilyich:
I - warehouse for hot-rolled coils, II - mill bay, III - machine room, IV - gas bell furnace bay, V - finished product warehouse; 1, 3, 8, 10, 12, 13, 19, 20, 22, 24, 26, 28 - overhead cranes, 2 - cross-cutting unit, 4 - transfer conveyors with tilters, c5 - packing units for sheet bundles, 6 - shears , 7 - continuous pickling units (CTA), 9 - combined cutting unit, 11 - guillotine shears, 14 - conveyor for feeding rolls to the mill, 15 - unwinder, 16 - working line of the mills, 17 - winder, 18 - outfeed conveyor, 21 - single-stall bell-type furnaces, 23 - baling tables, 25 - scales, 27 - tempering units, 29 - skin-passing cage, 30 - slitting unit, 31 - roll packaging units, 32 - double-stack bell-type furnaces, 33 - baling press
The mill is designed for cold rolling of strips with a cross-section of (0.4-2.0) x (700-1500) mm in rolls from carbon steels of ordinary quality (boiling, calm, semi-quiet): St1, St2, St3, St4, St5; carbon high-quality structural: 08kp, 08ps, 10kp, 10ps, 10, 15kp, 15ps, 15, 20kp, 20ps, 20, 25, 30, 35, 40, 45; ageless 08Yu, 08Fkp; electrical steel.
Boiling and mild steels are supplied in accordance with GOST: 16523-70, 9045-70, 3560-73, 17715-72, 14918-69, 19851-74 and technical specifications with a chemical composition in accordance with GOST 380-71 and 1050-74. Electrical steel is supplied in accordance with GOST 210142-75. [2]
