The main line of cold rolling mills generally consists of the same elements as hot rolling mills: working stand, frames, rolling rolls, spindles, gear stand, main clutch, gearbox, motor coupling, electric motor.

Cold rolling mill equipment

Working stands

The design of working stands is determined mainly by the range of strips being rolled, the nature of the work and the number of rolls. In ferrous metallurgy, four-high stands continue to be used in cold rolling mills for sheet products in most cases. These cages use closed cast steel frames. They are installed on slabs attached to the foundation. Drive rolls are work rolls if their diameter is over 400 mm, and support rolls if their diameter is 400 mm or less.

Figure 41 shows, as an example, the working cage of the five-stand NSHP-1700 OJSC Severstal. On this mill, support rolls with a diameter of 1500 mm have conical necks with a diameter at the base of 1120 mm, which provides the required strength and rigidity of the rolls with a rolling force of up to 22 MN. The length of the support roller barrel is 1600 mm. The cushions of the upper support rolls rest on hydraulic pressing devices (HPU), interlocked with mesodes (rolling force sensors). Through the HPU, the rolling force is transmitted to the upper cross members of the frame. The lower support roll pads rest on a wedge pressure device mounted on the lower cross members of the frames. The support rolls are installed in fluid friction bearings (FB) of the hydrodynamic type, which have high rigidity and high load-bearing capacity with small dimensions.

The work rolls are mounted in roller bearings with tapered four-row rollers. The rolling force is perceived by the work rolls, transmitted to the barrels of the support rolls, then to the journals and hydraulic pumps. The work roll pads do not contact the support roll pads, so elastic deformations of the work rolls in the vertical plane occur according to the beam pattern on elastic bases (the function of which is performed by the support roll barrels).

At NSHP 1700 of Severstal OJSC, the weight of the set of work rolls with chocks is 14.8 tons, the support rolls with chocks on the PZhT and traverse -

Closed-type beds with a cross section of 6000 cm2 posts and a weight of 118 g were used on the 2030 mill of NLMK OJSC.

On modern NSHPs, only hydraulic pressure devices are used. This is explained by the peculiarities of rolling technology at NSHP. The main purpose of pressing devices on mills of this type is to regulate the thickness of the strip, since the opening of the rolls after passes, as on reversing mills, does not change. Therefore, the pressing mechanism must have high speed, which electromechanical pressing devices do not have (limit value 2 mm/s*). The GPU allows acceleration up to 500 mm/s.

The hydraulic control unit ensures greater precision in the processing of control actions by eliminating backlash and elastic tightening of the pressure screw when rotating under load, which are characteristic of electromechanical control units. In addition, the GPU has low wear, high reliability and ease of maintenance. It is more compact and less metal intensive, which makes the working cage compact and increases its rigidity. The HPU, located at the top, is more convenient and 10-15% cheaper than the devices located under the lower cushion of the support roll.

On the 2030 mill, two cylinders per stand are installed in the working stand, the piston diameter is 965 mm, the stroke is 120 mm, the maximum perceived rolling force is 30 MN. When transferring support rolls, the pressure cylinders are secured using hanging devices. Figure 42 shows a diagram of a hydraulic pressure device.

Rice. 41. Working stand NSHP 1700 of Severstal OJSC: 1 - bed; 2, 3 - frame crossbars; 4.5 - support rollers; 6,7 - work rolls; 8, 9 - support roller cushions; 10, 11 - work roll cushions; 12 - hydraulic pressure device; 13 - medose; 14 — wedge pressure device; 15, 16 - fluid friction bearings

The actual position of the piston (clearance) is measured by sensors installed directly on the hydraulic cylinder. The sensor body is rigidly connected to the hydraulic cylinder, and the sensor rod is connected to the hydraulic cylinder rod. To eliminate errors in readings that may arise due to piston misalignment, two sensors are installed, located diametrically opposite. Maintaining the specified position of the piston is carried out as follows (see Fig. 42).

Rice. 42. Diagram of the gas pumping unit of mill 2030 of NLMK OJSC: 1 - hydraulic cylinder; 2 - actual piston position meter (position sensor); 3 - piston position sensor signal averaging amplifier; 4 - servo valve; 5 - amplifier

The setting of the thickness S0 (piston position) is set from the automatic thickness control system or manually by the operator from the remote control. This task enters amplifier 5, where it is compared with the actual position of the piston S^. This signal comes from meter 2 and is averaged in amplifier 3.

The actual hydraulic system of the pressure device drive consists of the following elements (Fig. 43): pressure gyrocylinders; an oil tank with automatic maintenance of oil level and temperature, which is done to stabilize its viscosity and system characteristics; two low-pressure pumps (one backup) (1.4 MPa) to power high-pressure pumps and pump oil through an auxiliary circuit with fine filters with a mesh size of 5-10 microns; two pumps (one working, one standby) of high pressure (25 MPa) of adjustable capacity to power the pressure cylinders; high-pressure fine filters with replaceable filter elements, return filters in the drain line; two high-pressure (25 MPa) accumulators; two low-pressure accumulators of 1 and 6 MPa, respectively; a control unit including a pressure reducer with pressure reducing valves that reduce the pressure from 25 to 6 and 1 MPa; two servo drive units for controlling hydraulic pressure cylinders, including two servo valves installed in parallel on the cage frame near the pressure cylinders; safety and control valves for relieving excess pressure; oil cooler. All hydraulic system pipelines are made of stainless steel.

Rice. 43. Diagram of the hydraulic system for driving pressure devices: 1 - hydraulic cylinders; 2 - oil tank; 3 - low pressure pumps; 4 - fine filters; 5 - high pressure pumps; 6 - high pressure filter; 7 - high pressure accumulators; 8.9 - low pressure accumulators (1 and 6 MPa); 10 - servo drive; 11 - control unit; 12 - reverse filter; 13 - refrigerator; 14 - safety and control valves

Installing two servo valves instead of one on each hydraulic cylinder reduces their dimensions and the weight of the spools. This is necessary to improve the operation of the system in dynamic mode, improve its frequency characteristics, and expand the frequency band of processed disturbances. By minimizing the mass of moving parts and the length of pipelines, the drive system of hydraulic pressure devices ensures processing of disturbances with a frequency of up to 80 Hz. It takes only 0.04 s to process a disturbance with a thickness of 10 mm. Simultaneously with the increase in performance, dynamic loads are reduced. In this system of hydraulic drive of pressing devices in all its links, the dynamic loads are lower than twice the static load. The hydraulic pressure device can operate in two modes: the main mode - regulation and the auxiliary mode - removing the rolling force.

When operating in regulation mode, oil from the tank flows through the suction pipeline to a low-pressure pump (1.4 MPa), which pumps it through a fine filter and supplies it to the input of the high-pressure pump. To create guaranteed backwater and eliminate cavitation in the high-pressure pump, the performance of the low-pressure pump exceeds the maximum performance of the high-pressure pump. The high-pressure pump, through barrier filters with a cell size of 20-25 microns, supplies oil to the control unit, high-pressure hydraulic accumulator and to the servos for controlling the pressure cylinders. From the servo drives, oil is supplied through flexible hoses to the piston cavity of the hydraulic cylinders, ensuring the specified piston movement.

If it is necessary to quickly relieve pressure and remove the rolling force, the rod cavity of the hydraulic cylinder is connected using servo valves to the pipeline of the control unit, through which oil reduced to 6 MPa is supplied. At the same time, the piston cavity is connected to the drain and the piston moves to its uppermost position.

To compensate for changes in the radius of the rolls during regrinding and to maintain a constant rolling level, a wedge device driven by hydraulic cylinders is provided, installed under the pads of the lower support rolls. Since the setting of the rolling line is not carried out under load, no significant force is required to move the wedge device and it is made quite compact.

One of the disadvantages of four-roll stands is the low rigidity of the roll assembly in the horizontal plane, since the work roll barrel has no support in this plane. As a result, even small gaps between the bearings, cushions and frame windows, caused by sliding fit tolerances and wear, lead to horizontal displacements of the vertical axial plane of the work rolls relative to the support rolls, that is, the work rolls find themselves in an unstable position, and their axes can warp. It leads to negative consequences for quarto flare operation: increased vibrations and axial forces occur in the roll assembly, and the size of the gap between the rolls is subject to unpredictable fluctuations, which reduces rolling accuracy. To eliminate these negative phenomena, a horizontal displacement of the vertical axial planes of the support and work rolls relative to each other is provided in the roller assembly (Fig. 44). Changing the position of the roll axes is ensured by shifting the holes in the work roll cushions for installing bearings and by adjusting shims between the cushions and supporting surfaces.

At the second generation NSHP, Anti-Bending of the work rolls was added to these systems, and the >Dp ratio remained the same as at the first generation NSHP. The advantage of anti-bending rolls, compared to the thermal effect of sectional cooling on them, was its speed.

In the 60-80s of the last century - the third generation of NSHP - the systems of anti-bending of rolls and their sectional cooling were improved and the joint use of both systems took place.

The design of the roll chock units of four-roll stands, developed by NIITYAZHMASH of the Uralmash plant, is shown in Fig. 45.

The work roll pads are located in the cage in such a way that their vertical axial plane 4 is offset relative to the vertical axial plane 5 of the support rolls by a distance “e”. The value of “e” can be changed by changing the thickness of the replaceable strips 11, fixed on the supporting planes (“mirrors”) of the housings 9, installed in the frame window, fixed on the side planes of the work roll pads. The support roller pads are also equipped with replaceable strips 14, through which they contact the vertical planes of the frame window.

Rice. 45. Assembly of cushions of the work and support rolls of a four-roll stand with hydraulic balancing cylinders of the rolls designed by NIITYAZHMASH of the Uralmash plant:

1,2 - work roll cushions; 3 - work rolls; 4, 5 - vertical axial planes of the working and support roll cushions, respectively; 6,7 - support rollers; 8 - replaceable strips; 9 - buildings; 10-bed; 11 - replaceable gaskets; 12, 13 - support roller cushions; 14 - replaceable strips; /5-19 - hydraulic cylinders; 20 - transfer rollers

Equipping mills with hydraulic bending cylinders, sectional collectors for thermal profiling of rolls and automated control systems for these devices ensured a significant increase in accuracy in the production of wide cold-rolled strips in the 70s of the 20th century.

However, technical progress in the automotive industry, construction industry and mechanical engineering, as well as competition from metallurgical enterprises, led in the 80-90s of the 20th century to further tightening of the requirements for the quality and accuracy of cold-rolled sheets and strips.

This problem was solved in different ways at the 4th generation NSHP.

One of them is to reduce the barrel diameter of the work rolls down to 200 mm while maintaining the barrel diameter of the support rolls in the range of 1300-1400 mm. At the same time, the ratio £>op /£)p became 3.7-7, which made it possible to roll wide strips (see Table 1) with a thickness of 0.2-0.3 mm with high accuracy and reduced energy costs for rolling. The reduction in the diameter of the work rolls dictated the need to transfer the main drive from the work rolls to the support rolls. Transferring the main drive to the support rolls solved both of these problems: it relieved the necks of the work rolls from tangential stresses, simplified the design of their end parts, which, as will be shown below, will facilitate the creation of the design of the work rolls and the mechanisms for their movement during axial shift.

Previously, stands with idle work rolls were used on small mills, most often multi-roll.

Another significant change in the design of the work stands was to equip them with devices for horizontal stabilization of the work rolls.

The horizontal stabilization scheme is shown in Fig. 46.

Rice. 46. ​​Scheme of horizontal stabilization of work rolls: 1 - work roll cushion; 2 - work roll; 3 - support roller

The forces Qr created by the cylinder plungers installed in the frame housings act on the work roll cushions, ensuring that the specified displacement “e” of the work roll relative to the support roll is maintained. The displacement value “e” is pre-set by separately adjusting the stroke of the plungers located to the left and right of the pillows. The scheme shown in Fig. 46, excluding the unstable position of the work roll pads in the cage, does not, however, prevent the horizontal deflection of the work roll barrel, that is, the described scheme solves the problem of horizontal stabilization of the work rolls only partially.

Therefore, when rolling thin strips with particularly stringent requirements for dimensional and shape accuracy, in stands with barrel diameters of work rolls less than 300 mm, horizontal stabilization is carried out using side support rollers, on the pads of which hydraulic cylinders act directly (Fig. 47, a) or - for greater rigidity - through the side support rollers (Fig. 47, b).

Rice. 47. Scheme of horizontal stabilization of work rolls: 1 - support rolls; 2 - work rolls; 3 - side support rollers; 4 side roller and support roller system. Q - roller pressing force

In fact, the circuits shown in Fig. 46 and 47 were a development of the MKW cage circuit (see Fig. 35, position 9), developed by Schlemann-Siemag. The drive in this stand is carried out through support rollers. The main advantages of such a stand are the same as those of multi-roll stands. Since the work rolls have a small diameter, the average pressure, force and rolling torque are significantly lower than in a conventional four-roll stand. This cage allows you to obtain large reductions in one pass and a large coefficient of equalization of thickness differences. It has the ability to regulate flatness by acting on the support rollers through bearing supports (see Fig. 47, b). For such stands, all the advantages arising from the small diameter of the work rolls take place: lower regrinding costs, lighter and cheaper machines, easier handling, lower roll consumption, etc.

In the 70s of the last century, the Shin Nippon Seitetsu company developed a six-roll stand with intermediate rolls moving in the axial direction. In this case, the rolls are arranged according to the diagram shown in Fig. 48 (we classify NSHPs with six-roll stands and small-diameter work rolls as the fifth generation).

The stand was called the HCM stand (High Control Midle) and was intended only for cold rolling.

Rice. 48. Layout of the rolls of a six-roll stand NSM: 1 strip; 2- work rolls; 3 -- intermediate rolls; 4- support rollers; 5 - direction of axial movement; b - direction of action of the anti-bending force of the rolls, R - reaction of the stand to the rolling force P;e - value characterizing the position of the intermediate roll

The first stand of this type was used in a single-stand reversible mill for cold calcination of strips with a thickness of 0.25-3.2 mm and a width of 500-1270 mm made of carbon and silicon steels. The mill was put into operation in 1974 at the Shin Nippon Seitetsu plant in Yawata. The technology of rolling in a six-roll stand using an automatic roll profile control system was mastered at the mill in 1977. In the same year, a six-roll stand was installed on the six-stand NSKHP-1420 of the same plant, and in 1979, a six-roll stand was first used on a temper rolling single-stand non-reversible mill in the line of a continuous annealing unit.

The use of axial displacement of the intermediate rolls of six-roll stands is equivalent to changing the bevels on the support rolls. It is known that if the length of contact of the work rolls with the support rolls coincides with the length of the contact of the work rolls with the strip, then the deflection of the work rolls exactly coincides with the deflection of the support rolls, but if there is no such coincidence, then a bending moment arises in the quarto stand, acting on the work rolls from the influence of the edge sections of support rolls located outside the strip width. Before the use of six-roll stands, conditions for the coincidence of the length of contact of the work rolls with the support rolls with the length of contact of the work rolls with the strip were attempted to be ensured by the use of bevels along the edges of the support rolls. In cold rolling mills, this length on each side of the roll barrel is usually 100-250 mm. When changing the width of the rolled strip, the length of the bevels should be changed, and this can only be done by transferring the rolls. To some extent, the problem was solved through the use of support rolls with double bevels: the outer bevel length is 50-200 mm with a large taper angle, and the inner bevel is 200-350 mm long with a smaller taper angle. But even in this case, it is not possible to achieve a solution to the problem for the entire range of rolled strips.

In six-roll stands, by moving the intermediate rolls in the direction of their axis, it is possible to change the length of the contact zone between the work and support rolls, combining it with the width of the strip. By changing the position of the base of the conical sections of the intermediate rolls so that it coincides with the edge of the rolled strips of different widths, as shown in Fig. 45 (the upper intermediate roll with the left edge of the strip, and the lower one with the right), the condition of equality of the contact length between the support and the working one is achieved rolls

In NSM stands, only intermediate rolls have axial displacement. The next step was the creation of stands with axial displacement of intermediate and work rolls (HCMW stands). The amount of displacement of the intermediate rolls is selected depending on the width of the rolled strips. The drive rolls in NSM and HCMW stands can be work, intermediate or support rolls, which is determined by the ratio of the diameter to the length of the work roll barrel.

The use of six-roll stands for cold rolling allows

— significantly improve the flatness and increase the stability of the transverse profile of the strips during their rolling and temper training;

— reduce the rolling force and torque through the use of small-diameter work rolls, and therefore reduce energy costs;

— increase the crimping capacity of the mill (also by reducing the rolling force), which allows the use of thicker rolled material, and therefore reduce the cost of its production at ShSGP;

— increase the yield by reducing the side trim (becomes possible due to a decrease in the thinning of the side edges of cold-rolled strips).

A further development of NSM stands was the development of UC (Universal Crown) stands, equipped with anti-bending devices for working and intermediate rolls. The combination of bending of the working and intermediate rolls makes it possible to vary the distribution of drawing coefficients across the strip width within a fairly wide range and along a variety of diagrams. This ensures that high-strength steel strips can be rolled with high flatness even when using large reductions. Modifications of UC stands differ in the ratio of the work roll diameter to the strip width. The drive rolls in UC stands can be backup, intermediate or work rolls, depending on the diameter to length ratio of the work roll barrel.

Six-roll stands were also developed by Schlemany-Siemag and Stahlwerke Bochum. The design features of these stands include the possibility of horizontal (in the rolling direction) movement of the work rolls (Horizontal Vertical Control - HVC system).

The cage developed by these companies is shown in Fig. 49. It is installed on a reversible cold-rolling mill at the Stahlwerke Bochum plant in Bochum (Germany).

Rice. 49. HVC stand diagram: 1 - small diameter work roll; 2 - mechanism for horizontal movement of work rolls; 3 - anti-bending device for intermediate rolls; 4 - mechanism for axial movement of the intermediate roll; 5 - drive of support rolls; 6 - hydraulic pressure device; 7 - multi-zone roll cooling device

The mill uses cylindrical work rolls (without initial profiling).

Technical characteristics of a six-roll reversing mill

Roll dimensions, mm:

thickness……………………………………………………………… 2-4

width…………………………………………………….. 750-1550

Dimensions of the finished strip, mm:

thickness………………………………………………………… 0.2-3

width…………………………………………………….. 700-1550

Roll weight, t………………………………………. up to 28

Rolling speed, m/s…………………………… up to 20

Diameter of roll barrels, mm:

workers………………………………………………………290-340

intermediate………………………………….. 460-500

support………………. ………………………… 1300-1420

Axial mixing range

intermediate rolls, mm…………………. 600-1600*

Adjusting the horizontal position of the work rolls:

regulation range, mm………………………. ±12

control force, kN……………………………. 450

Anti-bending force of intermediate rolls, kN 1200

Roll drive power, MW………………… 2×5

Torque, kN m…………………………. 240-165

Angular speed, r/s…………………………….. 0-4.1

Strip tension, kN…………………………….. 0-200

These figures give rise to very serious doubts. In other literature sources, we have not found a displacement of intermediate rolls of more than ±150 mm.

Rice. 50. Scheme of horizontal movement of the work roll in the HVC stand:

1 - rolling force; 2 - rolling moment; 5 - horizontal component of the rolling force; 4 - resultant horizontal force directed towards the intermediate or support roll; 5 - work roll; 6 - intermediate roll

Figure 50 shows a diagram of the movement of the work rolls relative to the intermediate rolls. Adjustment of work rolls in the horizontal plane allows efficient use of small diameter work rolls. In this case, the work rolls are shifted from the vertical axis of the multi-roll set so that they are supported by the intermediate rolls with a certain resulting horizontal force.

In addition, the features of the HVC stand include axial movement of intermediate rolls, support drive and a multi-zone roll cooling system. The use of HVC stands helps achieve high flatness, tight thickness tolerances and reduced strip edge thinning over a wide range of reductions per pass (especially with frequent changes in strip sizes).

Experience in operating the HVC stand at the plant in Bochum (Germany) has shown its high efficiency when rolling hard-to-deform steels. In this case, only cylindrical rolls were used.

Six-roll stands are also produced by Sundvig.

In six-roll stands, various combinations of roll diameters are possible. In practice, rolls of the following ranges are used: £>op = 1300-1525, D = 460-540, D = 260-470 mm.

The disadvantages of six-roll stands are:

— more complex design compared to quarto cages;

— uneven wear of the work rolls occurs, which increases the thickness of metal removal when regrinding the rolls;

— a decrease in the diameter of the work rolls leads to an increase in their loading cycles, which increases their consumption and causes an increase in the number of their transfers;

If six-roll stands were not widespread at ShSGP, mainly due to the complexity of their design, then at agricultural production they began to be widely used. At the same time, at NSHP the number of six-roll stands can vary from one (usually the last) to the entire mill being fully equipped with six-roll stands.

And yet, the next step in the development of means of influencing the flatness and profile of strips was the development by Schlemann-Siemag of four-roll stands with rolls having an S-shaped (or “bottle”) profile along the entire length of the roll barrel (Fig. 51) . The rolls are shifted relative to each other in opposite directions by the same distance, forming a symmetrical gap between the rolls and a transverse profile of the strip from rectangular to convex with different convexity values. It is also possible to obtain a concave strip shape, but such strips are not rolled due to their instability with respect to the rolling axis. The scheme was designated CVC (Continuously Variable Crown).

In the initial (without displacement of the rolls) position (Fig. 51, a), the gap between the rolls is the same along the length of the roll barrel and the strip is rolled with a transverse rectangular shape. When the tangs are shifted in the opposite direction, a convex strip shape appears. The greater the displacement, the greater the convexity of the strip. Profiling is performed along a curve close to a sinusoid.

The use of such rolls is possible in two-, four- and six-roll stands (stands of type CVC-2, CVC-4, CVC-6, respectively). In such stands, to expand the range of regulation, bending systems for working or intermediate rolls are used, depending on the type of stand. Due to the more complex configuration of the rolls, the distribution of contact pressure in the “working-support rolls” system will be described by more complex than second-order polynomials. Therefore, the equation of deflection (arrow of deflection) will differ from a parabola of even degree.

The developed roll profiling makes it possible to expand the variety of non-flatness defects that can be adjusted.

There is an opinion that since in stands with axial displacement of rolls the length of their barrels is greater than in traditional mills, it is possible to reduce wear on the work rolls by distributing it over a longer barrel of rolls. On the one hand, this is true, but on the other hand, the axial shift of the rolls entails an asymmetry of the load on the left and right sides of the rolls, which causes different inter-roll contacts and deformations of the roll system, different loads on the pressure screws, asymmetrical wear of the rolls along the length of the barrel, and, consequently, an increased layer of metal when regrinding rolls. And what is also important is that it is difficult to even make an approximate forecast of the wear of the surface of the rolls, and, consequently, to determine their service life before transshipment. The authors of the work draw attention to this fact. This paper presents the results of a detailed comparative analysis of the performance of four- and six-roll stands carried out by VAI employees. The layout diagrams of six- and four-roll five-stand cold rolling mills, shown in Fig. 52, are considered. The same figure shows the dimensions of the rolls, the magnitude of their axial mixing and the bending force of the rolls. Bottle work rolls are used for all schemes. The drive rolls are the work rolls. The range of the considered mills includes the following steel grades: two- and multi-phase, EF high-strength and soft, structural and strip, micro-alloyed and electrical.

At all mills, a four-roll stand is adopted as the last stand. The authors of the work justify this by the fact that the use of such a stand makes it possible to obtain a high quality strip surface with the required roughness and it is possible to more accurately predict the inter-transfer periods of rolls (this is mentioned above).

The study was carried out using a developed mathematical model of the rolling process and the interaction of the rolls with each other and the working rolls with the strip, as well as the temperature conditions of rolling and operation of the rolls.

The simulations and analyzes performed showed the following:

— from the point of view of capabilities, four- and six-roll stands are identical if the diameters of the work rolls are in the range of 400-520 mm and are comparable;

Rice. 52. Schemes and initial data for five-stand NSHP with a different set of four- and six-roll stands

— the elastic springback of the roller set of six-roll stands is 50% higher than that of four-roll stands;

— roll consumption is significantly higher in six-roll stands, both due to the larger number of rolls used and due to their axial displacement;

— capital costs for six-roll stands are approximately 10% higher than for four-roll stands.

Six-roll stands have advantages over four-roll stands in terms of strip flatness regulation.

Consequently, when choosing the type of stands for a new or reconstructed rolling mill, a preliminary technical and economic analysis should be done, on the basis of which a decision should be made on the advisability of using six-roll stands and their design.

The author of the work proposes to use the scheme proposed by the Schlemann-Siemag company as a methodological basis for such an analysis (Fig. 53). The diagram shows Various types working stands with varying roll diameters, drive patterns, systems for axial movement of rolls and their horizontal stabilization. The family of CVC stands shown in the diagram is arranged in order of increasing complexity of the design and expanding the range of adjustment of the inter-roll gap as the resistance to metal deformation increases, the thickness of the strip decreases and the requirements for its flatness increase. This figure gives only a qualitative picture, which can be formulated very briefly - the higher the requirements for the product, the smaller the final thickness of the strip and the higher the strength properties of the metal, the more complex the design of the stands used.

One of the latest developments of the Schlemann-Demag company was the creation of an 18-roll stand for rolling high-quality steel grades. The layout of the rolls of this stand is shown in Fig. 54 (HS system). Its features include the use of axial displacement and anti-bending of intermediate (“bottle” type) rolls, adjustable supporting force applied to the work rolls and multi-zone cooling of the work rolls. Roll diameters: working 140; intermediate 355; support 1350 mm. That is, the diameter of the work rolls has been reduced to 140 mm. The authors of the development report that such a rolling stand makes it possible to regulate both the waviness of the edge and the warpage of the strip with high accuracy, provide increased reductions, and increase the durability of the side support units.

Back in the early 80s of the last century, the Mitsubishi Jukogyo company developed the design of a four-roll stand with crossed rolls (Fig. 55).

In stands equipped with the PC (Pair Crossed Rolling) system, the work and support rolls (upper and lower systems) are combined into a block using traverses. The cages have a mechanism for crossing the axes of the rolls of the upper and lower systems at an angle of up to 1 degree. The principle of operation is based on the fact that the gap between the work rolls, created when they cross, begins to increase as it approaches the edges of the barrel with an increase in the angle of rotation of the rolls. This makes it possible to regulate the convexity of the strip profile over a wide range without the use of anti-bending force. The parallelism of the generatrices of the support and working rolls is maintained during rotation.

Crossing of rolls is carried out special mechanism, consisting of an electric motor and a worm gear, which drive traverses to regulate the position of the work and support roll pads.

The use of the PC system makes it possible to avoid roll profiling and compensate for thermal bulge and roll wear. The strip profile is adjustable in the range from -100 to +300 µm without anti-bending rolls and from -200 to +470 µm - using anti-bending rolls.

The main disadvantages of the PC system are the complex transmission of the drive of the rolls and the roller systems themselves, as well as ineffective control of the waviness of the strips (the warpiness of the strip is very well regulated). Therefore, stands of this type are not widely used in agricultural production.

It was previously noted that PZhT is used for NSHP support rolls. However, in last years roller bearings are beginning to be used (see Fig. 12). According to the work, this made it possible to reduce the longitudinal variation in thickness of cold-rolled strips by 2% in the braking and acceleration sections, and by 1% in steady-state rolling conditions. That is, the phenomenon of inconstancy of the oil film, which is characteristic of milking PHT at variable rolling speed, is excluded.

SHP also uses support rolls with adjustable convexity (VC rolls), developed by Sumitomo Kinzoku Kogyo (Japan). The roll consists of a band and an axle, between which there is an oil chamber.

Rice. 56. Block diagram of a system for automatic control of strip shape using rolls with a variable profile: 1 - support roll band; 2 - cylinder of fivefold pressure increase; 3 - pressure sensor and slip ring; 4 - electrohydraulic servo system; 5 - shape meter; 6 - anti-bending device for work rolls; 7- hydraulic power unit; 8 - control device and data processing; 9 - printing device; 10 - video control device (screen); 11 - control panel; 12 - roll cooling device;

I - direction of low pressure oil supply; II - liquid supply to the cooling device; III, IV - manual and automatic control of system operation

Oil under high pressure from the power supply is supplied to the oil chamber. With increasing pressure, the bandage expands and the forming roll changes its profile. Oil pressure varies from 0 to 70 MPa. In combination with anti-bending work rolls, this method is quite effective. In particular, it was implemented at the combined rolling-temper mill 2030 at the Sumitomo Kinzoku Kogyo plant in Wakayama (Japan). A similar roller design was developed by Blow-Knox Foundry and Mill Machinery (USA). Fig. 56 shows such a roll together with a system for automatically adjusting the transverse profile and shape of the strips.

It should be noted that all the described systems for regulating the transverse profile and flatness of cold-rolled strips work in combination with anti-bending of the work rolls. A mandatory element of systems for controlling the profile and shape of cold-rolled strips are appropriate sensors that record the transverse profile of the strips in various ways and issue a signal to the system that acts on the profile of the rolls directly during rolling.

Elements of the main line of agricultural production

In cold rolling mills, both individual and group drives of rolls are used, both working, support and intermediate, depending on the type of mill and its assortment. The most widespread scheme is the individual drive of rolls. Its use makes it possible to reduce the number of types of electric motors and select the optimal gear ratio for NSHP stands. In the case of using an individual roll drive, there is no gear cage, and the torque from the engine is transmitted through a combined gearbox. As a rule, a 1:1 gear ratio is not used on combined gearboxes.

Figure 57 shows the combined gearbox NSHP 1700. It consists of two cast frames and a cast cover, ten liners with Babbitt filling, in which two driving and two driven gear rolls are installed. The gearbox does not have intermediate mounting pads.

For high-speed SCPs, gear spindle connections with a barrel-shaped tooth profile are used. The largest skew angle at full operating torque for such a connection is 10-30° (with roll transfers up to 2°).

Fig. 58 shows a spindle connection consisting of two toothed bushings mounted on the end of the shafts of the combined gearbox; two clips connecting the bushings; four bushings mounted on the spindle shafts; two shafts; two coupling halves placed on the ends of the work rolls; balancing device (used only during handling of work rolls to fix them).

Toothed couplings with a barrel-shaped tooth are used as the main couplings on SHP (Fig. 59). They consist of two bushings and two cages, connected along a connector by horizontal bolts.

When using multi-roll stands, systems for crossing rolls and their axial shifting, the main line of agricultural production becomes significantly more complicated.

Rice. 58. Spindle connection NSHP 1700: 1 - coupling halves; 2 - shafts; 3 - balancing device; 4 - bushings; 5 - clips; b - toothed bushings

In particular, Fig. 60 shows a diagram of the axial shift of rolls, developed by Kawasaki Steel (Japan) in connection with a K-WRS type mill.

Rice. 60. Four-roll stand with a device for axial shifting of rolls: 1 - work rolls; 2 - support rollers; 3 - hydraulic cylinders for anti-bending work rolls; 4 - mechanism for axial shift of rolls; 5 - spindles; 6 - gear cage

The complexity of this device lies in the fact that, with a constant distance between the working and gear cage, the drive work rolls must move in the axial direction and at the same time an anti-bending system for the rolls must operate. How this problem was solved can be seen from the figure.

Auxiliary equipment for agricultural production

The entrance section of the NSHP is determined by the type of mill, mainly, what rolling method is used on it - coil or endless.

NSHP for coil rolling, introduced in the USSR in the 50-60s of the last century, is still in operation. They have also been preserved abroad. Such mills are equipped with cantilever coil unwinders with a wedge-type drum (Fig. 61).

The drum shaft is driven by an electric motor through a two-stage gearbox mounted on the unwinder body. For the purpose of greater stability of the roll (when unwinding the internal turns with high tension), a wedge drum with four segments is used. Wedging of the drum (increasing or decreasing its diameter) is carried out axially

Fig.61. Cantilever roll unwinder with wedge type drum

1 - drum shaft; 2 - electric motor; 3 - gearbox; 4 - unwinder body; 5 - wedge drum with segments; 6, 7 - guide bushings; 8 - sleeve; 9 - roller bearing; 10 - guide key; 11 - piston; 12 - end hydraulic cylinder; 13 - guide frame; 14 - bracket; 15 - end bearing by moving the drive shaft in guide bushings mounted in a sleeve supported by roller bearings in the unwinder housing. The sleeve is connected to the shaft by a guide key and has a keyed connection with the driven gear of the gearbox. The drum shaft moves inside the sleeve using a piston end of a double-acting hydraulic cylinder.

In order to ensure that the axis of the drum (roll) always coincides with the axis of the unit in front of which the unwinder is installed, it is possible to move the unwinder body along the frame guides. This movement (“swimming”) is carried out by a hydraulic cylinder mounted on a bracket using an automatic tracking system. To ensure that the drum can “float” when the strip is unwinding, the additional support must have free movement of the shaft end bearing in it.

The described unwinder is designed for unwinding rolls weighing up to 45 tons at a speed of up to 7 m/s, with a strip width of up to 1500 mm and a thickness of up to 2 mm (strip tension no more than 25 kN).

Such unwinders are also installed in front of cutting, galvanizing, annealing and other units.

Roll unwinders are used in two sets. When using one unwinder, the second one is prepared for work. This makes it possible to qualitatively prepare the ends of the roll for placing it into the mill.

Directly in front of the NSHP for coil rolling, a wiring table is installed, shown in Fig. 62. A special feature of the table is that it is designed for the task of rolling with a thickness of 1.5-6 mm and a width of up to 2360 mm. In addition to the function of directing the rolled stock into the rolls of the first stand, the guiding table is also designed to create rear tension on the strip.

Fig.62. General form wiring table with pneumatic cylinder

1 - roller table; 2 - horizontal idle rollers; 3,4 - guide wires; 5 - upper part of the table; b and 11 - lower part of the table; 7 - levers; 8- hinge; 9 - vertical idle rollers; 10 - screw mechanism; 12 - guides; 13- fixed frame; 14 - pneumatic cylinders; 15 - springs; 16 - rods; 17 - shaft; 18 - roll; 19 - gear; 20 tooth rack; 21 - brackets

The wiring table consists of a roller table with 2 idle rollers and guide wires. The upper part of the table is held by levers and hinges above the lower part of the table. To guide the strip along the length of the roll barrel, vertical idle rollers 9 are installed. Depending on the width of the strip, the rollers can be brought closer together using a screw mechanism.

The lower part of the table is mounted on the guides of a fixed frame. The roller table moves along the guides using pneumatic cylinders mounted on the frame. After the strip is precisely directed by the vertical rollers and its end has come out of the wires, the upper roller table is lowered using pneumatic cylinders and the strip is clamped between the wires. The clamping force of the strip is regulated by preloading the springs. When the rods of the pneumatic cylinders move to the right, shaft 17 rotates, which, with the help of side cranks and levers, will force the upper part of the table to lower and press the strip between the roller table and the wiring. With further movement of the rod to the right, the upper part of the table can no longer move down. Then the entire table will begin to move forward along the guides, due to which the end of the strip is brought to the rotating rollers and captured by them. After the strip is captured by the rollers, the rollers will create a slight rear tension of the strip, and the clamping of the strip by the wires will become weaker as a result of the upper arms with springs resting on the brackets mounted on the frame posts. When changing rolls, the table and frame are moved out of the working stand to the left using a manual roll drive, which has a gear 19 that meshes with a gear rack at the bottom of the frame. The maximum strip tension created by the wiring is 40 kN.

A wiring table of a different design is shown in Fig. 63. The upper part of the table is raised by the upper hydraulic cylinder and the strip is fed between the rollers. After this, the upper (moving) cassette is lowered, the wiring table moves to the first stand, and the front end of the strip is brought to the rolls and captured by them.

JSC NKMZ has developed a wiring table, the diagram of which is shown in Fig. 64. The wiring table consists of upper and lower parts, in which idle rollers and wiring guides are mounted. The upper part of the table is held above the lower part by pressure in the rod cavity of the pressure cylinder. The horizontality of the upper part of the table in the working position and when moving is ensured by a system of levers and

Rice. 63. Design of a roller wiring table in front of the first stand of NSHP 1700 with a hydraulic cylinder:

1 - hydraulic cylinders; 2, 3 - movable and fixed roller cassettes; 4 - non-drive sheet wiring

hinges To guide the strip along the length of the roll barrel, vertical idle rollers are installed. Depending on the width of the strip, the rollers can be brought closer together using a screw mechanism. The lower part of the table is mounted on the guides of the fixed frame. The roller table moves along the guides using a hydraulic cylinder 10 mounted on the frame. After the strip is precisely directed by the vertical rollers and its end has come out of the wires, the upper roller table is lowered using a pneumatic cylinder and the strip is clamped between the wires. After clamping the strip, the entire table begins to move along guides driven by a hydraulic cylinder, due to which the end of the strip is brought through wires to the rotating rolls and is captured by them. After the strip is picked up by the rollers, the rollers will create a back tension on the strip.

The table is designed to handle strips with a thickness of 2-4 mm and a width of 1520 mm at a filling speed of about 0.5 m/s. The maximum strip tension created by wires 3 and 4 is 40 kN.

Rice. 64. General view of the wiring table (NKMZ JSC): 1 - roller table; 2 - horizontal idle rollers; 3,4 - guide wires; 5 - upper part of the table; b - lower part of the table; 7 - levers; 8 - pneumatic cylinder; 9 - vertical idle rollers; 10 - hydraulic cylinder

The design of the wiring between the NSHP cages is shown in Fig. 65. Hydraulic clamps and wiring are located in each inter-cage space. The wiring 2 is moved using hydraulic cylinders; the middle wiring 3, installed behind the roller 5, is made in the form of a sheet hinged in the frame. Along the entire length of the wiring, covering the width of the rolled strip, five sensors are installed at equal distances (250-275 mm) in the direction perpendicular to the rolling axis, recording the strip tension (not shown in Fig. 65). Roller 7, controlled by two hydraulic cylinders, presses the strip against stationary roller 8 and goes to wiring 4, also made in the form of a sheet and driven by a hydraulic cylinder. The strip then goes into the press table and into the next cage.

Rice. 65. Wiring and press table between stands NSHP 1700: 1 - hydraulic cylinders; 2-4 - wiring; 5 - roller; b - frame; 7 - roller; 8 stationary roller; 9 - press table

At the NSHP for endless rolling, the entrance section differs significantly from the NSHP for coil rolling (see Fig. 37). In fact there are two of them. The first (main) is similar to the input section of the NTA (see Fig. 6 and 37). There are two sets of equipment for preparing the rolled material for welding, a welding machine, a loop storage unit, and then a feed roller system and a rolling mill. The parameters of the listed equipment are usually the same as those on the NTA. The second input section is used to supply coils for coil rolling - as at the NSHP for coil rolling. Second section on more NSHP of endless rolling is absent.

On NSHP combined with NTA, the input section is a tension station (see Fig. 17, 18), which provides tension on the rolled stock in front of the first mill stand. Since even the transfer of rolls occurs without releasing the strip from the mill, there is no operation of threading the front end of the strip.

Behind the last stand of the NSHP, pulling rollers and flying shears are installed (see Fig. 37). The need for these units arose with the introduction of endless rolling mills.

Typically, the pulling rollers for the NSHP are the same as in the NTA. On the 2140 mill from Thyssen Krupp Stahl AG, for the first time, traction rollers with hydraulic pressure mechanisms are used behind the last stand, which operate with a given pressure or movement, which ensures fast and precise adjustment of their position. In fact, this is a small rolling stand.

The shears, which are installed behind the last stand of the NSHP, are designed to cut the strip after winding a roll of a given mass or length onto a winder when implementing an endless rolling scheme. Drum-type shears operate at strip speeds of up to 5 m/s. The speed at which the strip is cut is limited not only by the capabilities of the scissors, but also by the durability of the belt winder. As the cutting speed increases, the impact of the front end on the sweeper increases, as a result of which the sweeper belt quickly wears out and requires stopping the mill to replace it.

The shears installed on the 2030 mill of NLMK OJSC are designed for cutting cold-rolled strips with a width of 900-1800 mm and a thickness of 0.3-3 mm.

The scissors consist of side frames; transverse cushions in which the bearings are located; drums with knives rotating in roller bearings; gearing of drums, couplings and drive. The cut is carried out automatically according to the seam or the mass of the roll. In both cases, the cutting command is developed in advance, and it is preceded by preparation of the mill, that is, a reduction in speed to 5 m/s, clamping of the strip, etc. After the cut, the mill automatically accelerates to optimal speed.

To wind cold-rolled strips after rolling at NSHP using the coil rolling process, drum-type coilers are used. These winders are designed not only to wind the strip tightly, but also to maintain the strip tension at a given level. Since the roll after rolling must be removed from the winder in an axial (horizontal) position, the winder drum shaft can only be made cantilever. Figure 66 shows a high-speed SCP winder with a gearless drive from an electric motor. This makes it possible to reduce flywheel torques and reduce the power of the drive motor.

The carrier shaft is driven through a drive shaft-sleeve, which at its end (right in Fig. 66) is connected to the electric motor shaft (it is not shown in the figure). The drive shaft-sleeve is connected to the carrier shaft by a guide key.

Fig.66. Coiler of a cold rolling mill with gearless drive:

1 - bearing shaft; 2 - drive shaft-sleeve; 3 - guide key; 4 - console drum; 5 - support with end bearing; 6 - plunger; 7 hydraulic cylinder; 8 - return springs; 9 - thrust disk; 10 - disk; I - check; 12 - plain bearing; 13 - body

Since the drum is cantilevered, to increase its strength and reduce deflection, before winding the strip, an additional support with an end bearing is placed at the end of the drum shaft. The drum is four-segment (at high strip tensions). To axially move the carrier shaft to the left (compress the wedge drum), the hydraulic cylinder plungers press the thrust disk 9, which moves the disk 10 and the internal pin passing through the hole in the drive shaft sleeve. In this case, spring 8 is compressed. The reverse movement of the carrier shaft (unclamping of the wedge drum) is carried out when the springs are unclamped (the pressure of the working fluid in the hydraulic cylinders decreases). The drive shaft sleeve is mounted on plain bearings located in the housing.

The described winder is designed for winding strips 0.5-2 mm thick at a rolling speed of 25 m/s. It is possible to wind rolls weighing up to 45 tons.

\Typical job description Roller of a cold pipe rolling mill, 3rd class

Job Description for Roller Roller of a 3rd Class Pipe Cold Rolling Mill

Job title: Roller of a cold pipe rolling mill, 3rd class
Subdivision: _________________________

1. General Provisions:

Subordination:
• The rolling mill operator of the cold rolling mill of pipes of the 3rd category is directly subordinate to...................
• The 3rd class pipe cold rolling mill operator follows the instructions.................................................... .............

(the instructions of these employees are followed only if they do not contradict the instructions of the immediate supervisor).

Substitution:

• Roller of the cold rolling mill of pipes of the 3rd category replaces................................... .........................................
• Replaces the 3rd class pipe cold rolling mill roller...................................... .......................................

Hiring and dismissal:
The roller of a cold pipe rolling mill is appointed to the position and dismissed by the head of the department in agreement with the head of the department.

2. Qualification requirements:

Must know:

• technological process of cold rolling of pipes
• device, operating principle and rules technical operation serviced equipment
• requirements state standards for cold rolled pipes
• steel grades and their rolling properties
• pipe range
• rolling tool used
• plumbing.

3. Job responsibilities:

• Conducting the technological process of rolling pipes with an outer diameter of up to 15 mm on one roller mill for cold rolling of pipes.
• Camp management.
• Handling of replacement rolling tools.
• Monitoring the quality of rolled pipes and roll lubrication.
• Trimming device control.
• Handling of calibers on roller mills for cold rolling of pipes.
• Setting up the mill.
• Performing routine repairs of the mill.

page 1 Job description Roller of a cold pipe rolling mill
page 2 Job description Roller of a cold pipe rolling mill

4. Rights

• The roller of a cold pipe rolling mill has the right to give instructions and tasks to his subordinate employees on a range of issues included in his functional responsibilities.
• The roller of a cold pipe rolling mill has the right to control the implementation of production tasks and the timely execution of individual assignments by employees subordinate to him.
• The roller of a cold pipe rolling mill has the right to request and receive the necessary materials and documents related to his activities and the activities of his subordinate employees.
• The roller of a cold pipe rolling mill has the right to interact with other services of the enterprise on production and other issues included in his functional responsibilities.
• The roller of the cold pipe rolling mill has the right to get acquainted with the draft decisions of the enterprise management concerning the activities of the Division.
• The roller of a cold pipe rolling mill has the right to submit proposals for improvement of work related to the responsibilities provided for in this Job Description to the manager for consideration.
• The roller of a cold pipe rolling mill has the right to submit proposals for the consideration of the manager on encouraging distinguished workers and imposing penalties on violators of production and labor discipline.
• The roller of a cold pipe rolling mill has the right to report to the manager about all identified violations and shortcomings in connection with the work performed.

5. Responsibility

• The roller of a pipe cold rolling mill is responsible for improper performance or failure to perform his job duties provided for in this job description - within the limits determined by the labor legislation of the Russian Federation.
• The cold pipe rolling mill operator is responsible for violating the rules and regulations governing the operation of the enterprise.
• When transferring to another job or being released from a position, the Pipe Cold Rolling Mill Roller is responsible for the proper and timely delivery of work to the person taking up the present position, and in the absence of one, to the person replacing him or directly to his supervisor.
• The roller of a pipe cold rolling mill is responsible for offenses committed in the course of his activities, within the limits determined by the current administrative, criminal and civil legislation of the Russian Federation.
• The roller of a pipe cold rolling mill is responsible for causing material damage - within the limits determined by the current labor and civil legislation of the Russian Federation.
• The cold pipe rolling mill operator is responsible for compliance with applicable instructions, orders and regulations for maintaining trade secrets and confidential information.
• The roller of a cold pipe rolling mill is responsible for compliance with internal regulations, safety regulations and fire safety regulations.

This job description has been developed in accordance with (name, number and date of document)

Head of structural

continuous mills with the number of stands 4-5-6.

Single stand multi-roll reversing mills

These mills are used for rolling small batches of sheets of a wide range, especially from hard-to-deform steel grades. The mills are easy to set up; rolling can be carried out with any number of passes. In ferrous metallurgy, quarto and 20-roll mills are most often used.

On single-stand mills, two rolling methods are used:

Sheet rolling lead to the quarto cages. The initial workpiece is a hot-rolled pickled sheet with a thickness of 3-10.5 mm; final thickness of rolled sheets up to 1.5 mm.

Rolling of rolled strips. Rolling is carried out in 20 roll mills with the diameter of the work rolls D p = 3-150 mm, barrel length L b = 60-1700 mm.

The range of such mills includes thin strips with a thickness of 0.57-0.60 mm, width up to 1700 mm. The initial workpiece is a pickled hot-rolled coil strip with a thickness of 3-4 mm. When rolling strips with a thickness of 0.002-0.10 mm the initial workpiece is a cold-rolled strip with a thickness of 0.03-1.0 mm, which has undergone “bright” annealing.

Single-stand reversing mills are equipped with coilers on the front and rear sides. Rolling is carried out in several passes, rewinding the strip from one coiler to another, with high strip tensions between the coilers and the working stand, with the mandatory use of technological lubricants to reduce the influence of friction forces on the rolling force. In Fig. Figure 33 shows a diagram of a twenty-roll cold strip rolling mill.

Rice. 33. Scheme of a twenty-roll cold rolling mill:

1 – work rolls; 2 And 3 – intermediate and support rolls; 4 – strip thickness meter; 5 And 7 – tension devices; 6 - band; 8 – winder drums

The mill has only two work rolls that deform the strip. The remaining support rolls are designed to reduce bending of the work rolls.

Continuous thin strip cold rolling mills

Continuous mills are used for significant production volumes of a relatively narrow range of strips. Modern continuous mills consist of 5-6 non-reversible quarto stands, the strip is simultaneously in all stands. Only one pass is made in each cage. Continuous mills are equipped with an unwinder on the front side and a winder on the rear.

The stock for continuous cold rolling mills is hot-rolled pre-pickled coils with a lubricated surface. Hot rolled coil strip is produced from continuous wide strip hot rolling mills. The thickness of the rolled material is, depending on the thickness of the finished product, 2-6 mm.

During cold rolling, large metal pressures occur on the rolls due to the hardening of the metal during deformation and the large influence of external friction forces. Cold rolling of coil strip is carried out with a significant tension of the strip between the stands and between the last stand and the winder with the obligatory use of technological lubricants. Strip tension provides a significant reduction in metal pressure on the rolls, which allows the strip to be rolled with high reductions for each pass and promotes tight winding of the strip onto the winder and its stable position between the rolls; the strip does not move along the roll barrel. The use of technological lubricants leads to a decrease in the influence of friction forces and a decrease in metal pressure on the rolls.

Strips with a thickness of 0.2-3.5 are rolled on 5-stand continuous mills mm, on 6 cages with a thickness of 0.18-1.0 mm. The width of strips rolled on these mills is up to 1200 mm.

On continuous mills, two rolling methods are used:

Roll rolling of strips. Each roll is rolled separately.

Endless rolling of coil strip. Adjacent rolls are butt welded before rolling.

Schemes of continuous coil rolling and endless rolling mills are shown in Fig. 34.

Rice. 34. Schemes of continuous coil mills ( A) And

infinite ( b) rolling:

1 – unwinders; 2 – working stands; 3 – winders; 4 - scissors; 5 – butt welding machine; 6 – loop-forming device; 7 – flying scissors

When rolling coils (Fig. 34, A) pickled hot-rolled coils from the warehouse are fed by crane onto a conveyor in front of the cold rolling mill, from which they are fed one at a time to the decoiler. Then the lever with the electromagnet is lowered, the magnet attracts the end of the roll, lifts it and feeds it into the feed rollers. These rollers feed the strip further into the input guide, which clamps and inserts it into the rolls of the first stand.

The rolling process begins at a low filling speed of 0.5-1.0 m/With. The strip is fed into the first stand, passed through the rolls of all stands and directed to the winder drum. When 2-3 turns of the roll are formed on the winder drum, the mill is accelerated to an operating speed of 30-40 m/With. When passing through the rollers at the rear end of the strip, the speed is again reduced. Since most of the strip is rolled at a variable speed, this leads to a change in rolling conditions, rolling force, elastic deformation of the stand, and ultimately to a change in the thickness of the strip along its length.

A significant improvement in strip quality is achieved in endless rolling mills (Fig. 34, b), on which the ends of the coils prepared for rolling are welded in the flow in front of the mill. As a result, the front end filling operations are reduced, the rolling speed is reduced only when welds pass through the rolls, and accordingly productivity increases and the metal consumption coefficient is reduced. Continuity of the process at the time of welding the ends of adjacent rolls that require stopping the strips is ensured by the presence of a loop storage 6 . When the coil welding process ends, a loop accumulation of the strip is created again; upon exiting the last stand, the strip is cut with flying shears 7 and is wound on winders 3 .

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Introduction

1. a brief description of technological process and mechanical equipment LPC-11

1.1 Purpose, design and operation of the cold rolling mill 2000

1.2 Analysis of existing cold rolling mill designs 2000

1.3 Rules for the technical operation of cold rolling mill units 2000

1.4 Measures to improve the reliability of cold rolling mill units 2000

1.5 Types and methods of metal quality control

1.6 Lubrication of the drive units of the cold rolling mill 2000

1.7 Occupational health and safety during operation of the cold rolling mill 2000

1.8 Security environment under conditions of LPC-11

Conclusion

Sources used

Application

Introduction

In recent years, the production of cold-rolled sheets, tin and strip has been increasingly increasing. This is due to the fact that in many sectors of the national economy there is a constantly growing need for thin sheet steel with high mechanical properties, precise dimensions, good quality surfaces. Cold rolling in combination with heat treatment makes it possible to produce thin sheet steel that meets these requirements. In 1977, the share of cold-rolled sheet

A modern method of cold rolling sheet steel is the coil method, in which the metal in the form of long strips is wound into rolls of large mass. For rolling thin-sheet steel in coils, mainly continuous mills are used, and for small production volumes, single-stand reversing mills with a four-roll stand and multi-roll mills are used. Coil rolling on continuous and single-stand mills occurs with strip tension. Sheet cold rolling is used much less frequently on single-stand reversing mills (without tension).

Improvement of cold rolling technology follows the path of increasing the accuracy of finished products due to: the rigidity of the working stands; application of means of elastic anti-bending of rolling rolls; improving the quality of rolls and equipping mills with automatic control systems for sheet thickness during the rolling process.

The relevance of pre-graduate practice is due to the fact that increasing efficiency industrial production and cost reduction in all parts of the metallurgical cycle largely depend on the rational organization of the production process, repairs, as well as the rationality of various technical solutions.

The purpose of pre-graduation practice is to test the professional readiness of the future specialist for independent labor activity and collecting materials for writing a graduation project.

1 . a brief description oftechnological process and mechanical equipment LPC-11

Technological process

The five-stand tandem mill is connected to a continuous pickling line and at the output section includes a device for double winding of rolls (two tension drums) and a built-in control station. The CVC 4-roll stand configuration allows rolling to meet economical and quality requirements.

Handling work support rolls requires stopping the entire line (Pl - TCM). As a rule, transshipment is carried out during downtime due to Maintenance or pickling/oiling (P/O) when there is no stripe on the line. metal rolling unit

Actuators of process control systems include:

Hydraulic fluidization AGC in cages No. 1 - 5

Positive and negative bending of work rolls in stands No. 1 - 5. Axial shift of working rollers in stands No. 1-5 (CVC - 4PLUS)

Multi-zone cooling device in a closed-loop flatness control system in stand No. 5

Strip thickness control model, thickness control, flatness control, seam detection and tracking device.

To guide the front end of the strip during threading and during strip cutting and to secure the strip when changing support rolls, the following equipment is installed on the support frame immediately in front of stand #1:

Strip clamping device/cut clamp;

Cross cut scissors;

Side strip guide.

In addition, additional supports and guides are installed for

the following measuring devices located at the inlet:

Strain gauge;

Thickness gauge;

Weld detector.

Mill stands

On cages No. 1-5 the following are installed:

Hydraulic cylinders for adjusting the roll opening with quick response and low friction coefficient. Hydraulic cylinders in all stands are equipped with pressure sensors:

Single-stand control system for continuous control of the rolling line;

Cassette frame window with integrated upper support roller balancing system and system; positive/negative bending of work rolls with servo regulation

System of dynamic axial shift of work rolls with servo-hydraulic control;

Drive of work rolls by means of universal drive articulated spindles, gear reducers, gear couplings and one modern AC main drive motor on each stand;

The piping of the mill stand is of a modular type, ensuring reduction of installation time and quick start-up of the mill (all-in-one design).

Pickling unit

Entrance etching area

The coil transport system, located between the hot coil storage bays and before the pickling and the inlet section of the pickling unit, mainly consists of: a walking beam for moving the rolls in a vertical position, a roll transport trolley, a roll turntable, a second roll transport trolley, a walking beam with a preparation station, a shuttle trolley and two roll trolleys. In the hot roll storage bay, the rolls are loaded onto roll platforms using a crane installed in the bay.

Using the first walking beam, the coils (in a vertical position) are transported in a transfer position (stationary coil rack), from where the first transport trolley removes the coils and transfers them to the tilter.

A tilter turns the rolls over, and a second roll transport cart picks up the rolls in a horizontal position and transports them to a second walking beam conveyor. The walking beam transports the rolls step by step to the roll platform, which is then where the rolls are transferred to the shuttle car.

Entrance area

After uncoiling drum No. 1 and No. 2 are released as described below, the strip is transferred to a waiting position in front of the welding machine: the filling table is raised and moved towards the coil, while the shock absorbing roller is activated.

Using the unwinder, the front end of the strip moves forward towards the dividing shears. After this, the rollers of the pulling roller block and the straightening machine will close, and the head part of the strip will be tucked into the dividing shears. Using a sensor, the head of the strip is detected, and the length of the strip is measured by a pulse generator on the input block of the pull rollers. After centering the leading edge of the strip, the trimming pull rollers are activated and the front part of the strip is automatically cut on the dividing shears.

Before the tail part of the strip of the previous roll exits, the unwinder automatically slows down the operation of the input section. When the tail extension speed is reached, the

straightening machine rollers, shock-absorbing rollers of the guide roller block No. 1 and tension station No. 1. As soon as the tail section leaves the unwinder, the drum is compressed. As soon as the tail of the strip passes through the straightening machine, the block of traction rollers and the straightening machine rollers are retracted. After this you can

Carry out the same procedure as described above to load the next roll. A measuring device is provided to measure the thickness of the strip. The straightened tail of the strip moves towards the No. 2 dividing shears, where it will be cut into approximately 1 m lengths.

After dividing the strip, the tail section moves towards the welding machine, and the drive shock-absorbing roller of the roller guide block and tensioner unit, located in front of the strip accumulator, will be stopped before the tail section of the strip stops, so that the welding machine and guide roller No. 1 can a loop of strip will form.

The separated tail section will be cut into substandard sheets before the dividing shears. During this cutting cycle, by calculating the remaining tail length, the minimum length limits for the last substandard sheet will be set according to the preset total cut length data.

During the cutting operation of the trimming shears, the upper pull rollers of the pull roller units are lowered to trim in front of the shears. Substandard sheets fall onto the turntable (upper pass line) or directly into the trim chute (lower pass line). The turntable at the top of the aisle will tilt upward to guide the trim into the scrap bins located in the scrap bin area.

Strip welding

The welding process begins after positioning the head and tail parts in the welding machine. To get more detailed information For the welding process, see the relevant paragraph of the technical specification.

Once welding is complete, a hole will be made using a punch press to locate the weld seam. The strip is then released and the inlet section is ready to begin operations again.

Input storage area

When the acceleration of the inlet section begins, the shock absorbing rollers of the roller guide block No. 1 and the tension roller No. 1 rise. At this point, the strip passes through the No. 1 guide roller, No. 1 tension roller and deflection rollers into the strip transport area, where it will be guided along a long section to the main span of the pickling unit. In this section, the strip will pass through guide roller No. 2, deflection roller and tension roller station No. 2 to the input looper.

Guide roller No. 1 compensates for the deviation of the strip from the center in the input section; as a result, after passing through the tension roller station No. 1, the strip is fed to the transportation section in a centered position. Guide roller No. 2 compensates for the deviation of the strip from the center of the upper conveying section, as a result of which, after passing through the tension roller station No. 2, the strip enters the input looper in a centered position.

The deviation of the strip movement from the center in this looper is compensated using directional roller No. 3, 4 and 5, which allows the strip to be transferred to the deflecting roller standing in front of the straightening machine in a centered position.

The deflection roller is equipped with strain gauge sensors to control the strip tension in front of the stretch bending block.

Correct-stretching machine

The strip passes through a straightening machine. In this area, the bending stress is superimposed on the tensile stresses in the material due to the bending of the strip around a roller of a relatively small diameter. Two rollers are designed to bend the strip in both directions, the edges being stretched until a long lasting deformation is obtained. Tensile stress is created due to the difference in speed of the tension rollers, which are located in front of the existing block. The stretching speed corresponds to the difference in speed between rollers No. 3 and No. 4.

Tensile stress is created due to the difference in speed of the tension rollers, which are located in front and behind the existing tensile bending block. The stretching speed corresponds to the difference in speed between spans No. 3 and No. 4.

After the straightening machine, the strip is sent to the etching area.

Pickling/chemical processing area

Due to its high operational flexibility and efficiency, the pickling area is divided into separate pickling chambers with different concentrations of metals and acids. They are separated from each other using two rubberized rollers, which are connected to the intermediate section.

Each pickling bath is assigned to one circulation tank, which ensures the flow of acid into the pickling bath. These tanks are also used as acid holding tanks if acid is drained from the pickling baths during strip downtime. Also, the acid cascade works through these circulation tanks.

The circulation tanks are connected by a common pipeline for faster filling of the acid drain tanks.

The top edge on both sides of the pickling baths is shaped like a water drainage trough to ensure perfect pressing, with the bath lids on top. They are made of plastic. This submerged part forms the profile of the vortex etching area.

Both covers (top and submersible covers for the pickling channel) are driven by hydraulic cylinders.

The temperature of the etching solution is adjusted automatically.

The spent acid is automatically pumped to a regeneration unit. The waste acid flow is pre-calculated using the feed-forward model.

The washing section on the pickling line will have the form of a cascade. The upper edge of the rinsing bath is a trough for water drainage and forms one line with the pickling baths. The lids are the same as those on the pickling tank, except for the submersible portions of the lids.

Collecting tanks that circulate the acid are built into the wash water circulation system. They also have horizontal centrifugal systems installed.

The rinsing water produced in rinsing section I is collected in the rinsing water holding tank.

Before the first pickling bath, a special pre-wash bath will be installed, which will perform the function of washing the strip in case of reverse flow.

The pickling and rinsing baths have grooves from which the shaft necks of the rubber rollers extend out. These openings are closed using double sliding flaps.

The drying device, installed after the washing section, consists of two sections: a high-pressure zone and a low-pressure zone, into which air is supplied by a fan. The low pressure zone is created by a hot air recirculation system.

Aggressive vapors that form due to high temperatures on the remaining surface of the baths in the pickling and rinsing area, as well as inside the acid recirculation tanks, are sucked off to prevent them from appearing on the line. Before removing this aggressive vapor from the coating level, it must be neutralized, i.e. cleaned in accordance with the standards for the composition of industrial emissions, which are developed by the competent authorities for the proposed facility.

Intermediate storage area

After chemical treatment, the strip passes through the centering roller block No. 6 and the tension roller block No. 6 into the loop storage unit of the output section No. 1. A tension measuring device is installed in front of the loop storage unit No. 1 in the output section, which controls the strip tension. This loop accumulator is used to ensure a constant etch rate in the etch section while measuring the strip width in the edge shear section.

After loop storage no. 1, the strip is directed through control devices no. 7 and 8 to the section of edge-shaped shears.

Edge trimming scissors

The area for edge trimming shears consists of 2 rotating platforms, on which 2 pairs of edge trimming shears and edge shredders are installed. Quick change of edge trimmers is done by turning the platform to. During operation of the line, it is possible to replace the knives of the edge trimmers and edge cutters using special tools. In this area, if it is necessary to change the width of the strip, use the weld detection device and automatic device To slow down the strip, stop the strip so that the weld is in the area of ​​the side die-cut press.

After the notch is made, the strip is sent to the edge trimming shears.

Once the strip width is changed, the weld passes through tensioner No. 4 and deflection roller and guide roller and is sent to the output loop collector No. 2. Also, in the area of ​​edge trimming shears, an automated edge trimming quality control device is installed. In addition, an automated strip surface inspection device is provided in this section.

Output storage area

A device for measuring strip tension is provided near the deflecting roller in front of the output loop storage unit No. 2.

The output loop storage unit No. 2, which has the shape of a 6-thread storage unit, is located under the roller floor, under the edge trimming shears area. Guide devices No. 9, 10, 11 and 12 align the strip in the center of the looper area before it is sent to tension device No. 8.

Output looper No. 2, located between the edge trimmers and the TCM input section, performs two main functions:

Accumulates stripe when changing rolls in tandem when combining tasks,

Guarantees tandem operation during edge trimming when combining tasks.

Also, both output loopers can be used together to accumulate strip when changing work rolls in a tandem cold rolling mill.

In this case, both storage tanks are emptied before the transfer begins, and the etching rate is reduced. Thanks to this, it becomes possible to continue operating the etching section at a low speed, but without stopping the line.

Under normal circumstances, the storage carts of both loopers are installed in an intermediate position. This allows the line to continue operating in different sections for a certain period of time in case of any problems or unplanned stops.

Connection section

The strip is fed through guide device No. 13 to the connection area.

Guide roller No. 13 performs the incorrect position of the strip before. Then it will be directed through tension device No. 7 to the cold rolling tandem mill.

The last tensioner is used to create the required strip tension for the first tandem stand.

Assortment LPC-11

Geometric dimensions of the strip rolled on a tandem mill 2000:

strip thickness: from 0.28 to 3.00 mm;

strip width: from 880 to 1880 mm (without trimming side edges), from 850 to 1850 mm (with trimming side edges).

Parameters of cold rolled coils:

internal diameter of cold rolled coil is 610 mm. It is allowed to produce cold-rolled rolls with metal or cardboard cores;

outer diameter of cold rolled coil: 1200 - 2500 mm;

weight of cold-rolled coil: no more than 43.5 tons.

Rolls with a diameter of less than 1200 mm are considered defective.

The parameters of cold rolled coils must meet the requirements:

STO MMK 2305, STO MMK 2259, STO MMK 2095, VTI 101-P-HL 11-39, VTI 101-P-HL 11-40 or ND for shipment.

Rolling with reductions that do not comply with Table 1 is allowed, provided that the cold-rolled steel meets the requirements of regulatory documentation and the loads on the equipment do not exceed permissible limits. The decision on rolling is made by the senior mill foreman or the shift foreman of the rolling section, subject to the fulfillment of the order conditions.

In terms of dimensions, maximum deviations in thickness, width, flatness, telescopicity and surface quality, cold-rolled coils must comply with the requirements of the current normative documents for shipment.

The production of cold-rolled steel on the tandem mill 2000 is carried out strictly according to the order specified in the pickling and rolling shop PRB task, taking into account the formation of assemblies in accordance with this TI.

1 .1 Purpose, device and operationcold rolling mill 2000

A rolling mill is a set of equipment in which plastic deformation of metal occurs between rotating rolls. In a broader sense, it is a system of machines that performs not only rolling, but also auxiliary operations: transportation of the original billet from the warehouse to heating furnaces and to the mill rolls, transfer of rolled material from one gauge to another, turning, transportation of metal after rolling, cutting into pieces , marking or branding, editing, packaging, transfer of finished products to the warehouse, etc.

Elements of the main line of a cold rolling mill (CRM)

The main line of cold rolling mills generally consists of the same elements as hot rolling mills: working stand, frames, rolling rolls, spindles, gear stand, main clutch, gearbox, motor coupling, electric motor.

In cold rolling mills, both individual and group drives of rolls are used, both working, support and intermediate, depending on the type of mill and its assortment. The most widespread scheme is the individual drive of rolls. Its use makes it possible to reduce the number of types of electric motors and select the optimal gear ratio for NSHP stands. In the case of using an individual roll drive, there is no gear cage, and the torque from the engine is transmitted through a combined gearbox. As a rule, a 1:1 gear ratio is not used on combined gearboxes.

For high-speed SCPs, gear spindle connections with a barrel-shaped tooth profile are used. The largest skew angle at full operating torque for such a connection is 10-30° (with roll transfers up to 2°).

Also, cold rolling mills have a spindle connection consisting of two toothed bushings mounted at the end of the shafts of the combined gearbox; two clips connecting the bushings; four bushings mounted on the spindle shafts; two shafts; two coupling halves placed on the ends of the work rolls; balancing device (used only during handling of work rolls to fix them).

Toothed couplings with a barrel-shaped tooth are used as the main couplings in SHP. They consist of two bushings and two cages, connected along a connector by horizontal bolts.

The design of working stands is determined mainly by the range of strips being rolled, the nature of the work and the number of rolls. For cold rolling mills of sheet products, four-roll stands are used. The work rolls are mounted in roller bearings with tapered four-row rollers. The rolling force is perceived by the work rolls, transmitted to the barrels of the support rolls, and then to the journals of the hydraulic pump. The pads of these work rolls do not contact the pads of the support rolls, therefore elastic deformations of the work rolls in the vertical plane occur according to the beam pattern on elastic bases.

The hydraulic control unit ensures greater precision in the processing of control actions due to the elimination of backlash and elastic tightening of the pressure screw when rotating under load, which are characteristic of electromechanical control units. In addition, the GPU has low wear, high reliability and ease of maintenance. It is more compact and less metal intensive, which makes the working cage compact and increases its rigidity. The HPU, located at the top, is more convenient and 10-15% cheaper than devices located under the lower pad of the support roll.

1 .2 Analysis of existing cold rolling mill designs 2000

Classification of cold rolling mills

By purpose: rolling, training, rolling and training.

By nature of work: continuous, reversible, sheet, roll, endless.

By number of rolls: four-roll, five-roll, six-roll, twelve-roll, twenty-roll, thirty-two, thirty-six, special.

According to the number of cages: single-cage, two-cage, three-cage, four-cage, five-cage, six-cage.

Appendix 1 shows the classification of cold rolling mills according to the number of rolls and working stand.

1 .3 Technical rulesoperation of cold rolling mill units 2000

On modern rolling mills, scale is removed from under the roller tables using hydraulic, dry or combined methods. A channel is made in the foundation under the roller table into which scale falls from the roller table rollers during transportation of rolled products along them. From the channel, scale is washed off with water (hydraulic method) into a settling well or removed by conveyor (dry method) into a common collection tank. With the combined method of removing scale, both first methods are combined: hydraulic - for removing small scale and dry - for removing large pieces of scale.

It is also necessary to ensure that the rollers do not come into contact with the flooring slabs due to the movement of incorrect laying of the latter, as this can cause premature wear of the rollers or their jamming.

It is very important to ensure regular, timely supply of lubricant to the friction units of the roller tables and in sufficient quantity, since otherwise heating of the parts and their failure is inevitable.

In roller conveyors with a group drive, bevel gears and plain bearing shells are subject to the most accelerated wear. This is especially observed in furnace and working roller tables of crimping mills, which, in contact with hot metal, become clogged with scale falling off the metal.

The use of a centralized lubrication system on roller conveyors prevents rapid wear of bearing shells, reducing their consumption several times.

Therefore, when caring for roller tables, the main attention should be paid to systematically cleaning them from scale and providing the bearings with lubricant.

To avoid mixing of liquid oil with grease, it is recommended that the roller bearings adjacent to the gear oil baths be lubricated with the same oil as the bevel gears.

To reduce the effect of heating, it is advisable to cool the rollers with water, installing sprinklers under it in the form of tubes with drilled holes.

When accepting a shift, check:

do all the rollers rotate;

is there any runout of the rollers in the bearings;

whether the inter-roller plates are shifted and whether they are in contact with the rollers;

serviceability and fastening of guide rulers;

serviceability of roller cooling systems;

supply of thick lubricant to the friction units upon activation of the feeders;

oil level in gearboxes according to oil indicators: add oil if necessary;

supply of thick and liquid lubricant to the roller bearings, transmission shaft, and gear shafts. If necessary, adjust the amount of lubricant supplied to the friction units using the feeder pistons, and also clean the oil channels and trays from dirt;

through the inspection hatches in the gearbox covers, check the reliability of the fastening of the gears on the shafts, as well as the radial and axial clearances of the shafts in the bearings; Eliminate detected malfunctions in accordance with the “Rules for the operation of standard parts.”

Shifts are transferred in the following order:

at the end of the shift, control station drivers, operators and equipment repair mechanics handing over the shift are required to write down in the shift acceptance log data on the condition of the equipment being serviced, faults,

that were discovered during work or violations of the Rules and measures taken to eliminate them, and also notify the shift taker about this:

the person accepting and handing over the shift jointly inspects the equipment they service, eliminates any faults found, and then reports to the foreman (foreman) that the shift has been accepted and the condition of the equipment;

malfunctions detected upon acceptance of the shift and not recorded in the log of the person handing over the shift are recorded by the personnel accepting the shift.

In case of detection of malfunctions in which the operation of the equipment is prohibited, the person taking the shift informs the head of the shift personnel of mechanics or the shift supervisor (the equipment can be put into operation only after the malfunctions have been completely eliminated and permission to start has been received); the transfer of the shift is confirmed in the acceptance log by the signatures of the persons accepting and handing over the shift, after which the shift is considered transferred (accepted).

Inspection of equipment during shift handover should begin with personnel taking over the shift with the equipment running (at the end of the previous shift). When inspecting mill equipment during shift handover, it is necessary to check:

the condition of parts, assemblies and mechanisms, during the operation of which malfunctions were discovered in the previous shift, and eliminate them;

Are there any characteristic noises, shocks and increased heating in bearing units, couplings that arise as a result of the wear of their parts or unsatisfactory lubrication; eliminate detected faults;

the condition of the gears in gearboxes, gear stands, open gear drives - by the nature of the noise (before the mill stops for shift transfer), as well as by the presence of abnormal vibrations and shocks in the drive elements; eliminate detected faults;

the condition of pipelines and flexible hoses for supplying water, lubricant and compressed air to the mechanisms; if necessary, repair or replace pipelines, hoses and fittings;

supply of lubricant to friction units from centralized grease lubrication systems - through the operation of feeders; from circulating liquid lubrication systems to bearings - according to oil flow indicators (OCI), the diameter of which should not be within 3 - 8 mm, depending on the points being lubricated; to gears - according to oil flow indicators (UFL), the flags of which must be open; if necessary, adjust the amount of lubricant supplied to the friction units;

the level of lubricant in gearboxes and transmission baths in accordance with production and technical instructions;

proper operation of individual manual lubricating devices and the presence of lubricant in them; if necessary, refill with lubricants;

are there any oil leaks from couplings, gearboxes and other components at their seals;

presence of lubricant in oil baths; if necessary, add lubricant to them;

fastening of couplings, spindles, gearboxes, bearing frames, levers on shafts, axle holders, counterweights and other parts and assemblies, the loosening of which during operation can cause equipment to stop or fail;

operation of pneumatic cylinders and air distributors; If there is an air leak, tighten or replace the seals;

serviceability of brake devices, limit and limit switches, alarm systems, interlocks and instrumentation;

proper operation of starting, blocking, braking devices and devices;

if necessary, troubleshoot or adjust the operation of these devices and devices;

presence and serviceability of fences;

cleanliness of equipment and workplace;

availability and serviceability of tools and spare parts.

Gears with tooth wear exceeding 30% of the nominal thickness, or with cracks on one or more teeth, must be replaced. Also, rollers with damaged journals or wear exceeding 10% of the nominal size should not be allowed to operate. Wear of roller barrels is allowed no more than 30% of the original thickness. Rollers on which these defects are found should be replaced. The gap between the shaft journal and the liners is allowed to be no more than five times that provided by the system of tolerances and fits, and wear on the transmission shaft journals is no more than 12% of the nominal size.

When inspecting the roller table, it is aligned with the geometric axis; check mutual arrangement transmission axles and roller axles and adjust the position of the transmission shaft to ensure proper engagement of all bevel gear pairs.

To reduce roller conveyor repair time, it is recommended to use the nodal method, replacing the following components:

separate gearbox shafts with gears and rolling bearings;

roller assemblies (axles, bevel gears, roller barrels and rolling bearings);

assembled transmission shafts (with bevel gears, coupling halves and rolling bearings).

For particularly quick replacement, it is recommended to have in stock several assembled rollers, the first gearbox shaft assembled with a coupling half and rolling bearings, separate transmission shafts assembled with gears, coupling halves and rolling bearings.

1 .4 Measures to improve the reliability of cold rolling mill units 2000

Reliability is the property of an object to perform specified functions, maintaining over time the value of established operational indicators within specified limits, corresponding to specified modes and conditions of use, maintenance, repairs, storage and transportation.

Durability is the property of an object to continuously remain operational for some time or some operating time.

Analysis of factors influencing the strength of parts, as well as machine operating experience, makes it possible to establish measures that can improve the performance properties of parts. The harmful effects of elastic deformations can be reduced by increasing the rigidity of parts. It is more expedient to increase rigidity by changing their section shapes, loading conditions, type and placement of supports, and using structures in which elements work in tension and compression rather than in bending.

Maintenance of cold rolling mills usually comes down to timely periodic cleaning of them from metal scraps, scale, waste lubricant and other contaminants. It is also necessary to ensure that the rollers do not come into contact with the deck slabs due to shifting or improper laying of the latter, as this can cause premature wear of the rollers or their jamming.

The use of a centralized lubrication system on roller conveyors prevents rapid wear of bearing shells, reducing their consumption several times. To avoid mixing of liquid oil with grease, it is recommended that the transmission shaft bearings and roller bearings adjacent to the gear oil baths be lubricated with the same oil as the bevel gears.

To increase the wear resistance of roller shaft journals and transmission shafts operating under normal conditions, they are subjected to surface hardening with high frequency currents or gas flame, bringing their hardness to 45-50 HRC. The journals of rollers operating in difficult conditions are surfaced with PP-3X 2V 8 flux-cored wire. The roller barrels are also strengthened by surfacing with PP-3X 2V 8 flux-cored wire.

When transporting hot metal, a sudden stop of the roller table should not be allowed, since stationary hot metal on the roller table rollers causes excessive and one-sided heating and distortion, leading to failure of the roller table.

To reduce the effect of heating, it is advisable to cool the rollers with water by installing spray tubes under them in the form of tubes with drilled holes.

Roller table bevel gears are made from grade 45 steel with volumetric hardening to a hardness of 320-380 HB, forged gears are made from grade 50 steel with surface hardening to a hardness of 40-50 HRC.

The Interplant School on Hardening of Metallurgical Equipment Parts recommends manufacturing roller table gears from steel grades 20 and 20X, carburized and hardened to a hardness of 32-38 HRC.

1 .5 Types and methods of metal quality control

After the production of cold-rolled steel on a sample 7 m long, quality control of the manufactured product is carried out after the transfer of work or support rolls, as well as periodically every fourth hot-rolled coil with the entry of control thickness measurements into the production report of the tandem mill 2000.

The control sample is cut out with drum cross-cut shears in the output section of the mill when dividing the strip into rolls. The cut sample stops on magnetic belt conveyor No. 2 or by means of magnetic belt conveyor No. 1 - No. 3 and is transferred to belt conveyor No. 4 with a device for clamping and turning the strip.

The cut sample is clamped and tensioned on the strip tilting device.

The selected sample is used to control the quality of the following rental parameters:

The thickness of the rolled strip is measured with a micrometer, in accordance with GOST 19904. It is controlled by the inspection operator, the senior rolling operator. The result of the control measurement is entered into the production report of the tandem mill 2000.

The width of the rolled strip is measured with a tape measure. The inspection operator, senior rolling operator, supervises. The result of the control measurement is entered into the production report of the tandem mill 2000.

Surface quality of rolled products at top and bottom (visually). Inspection of the bottom surface of the strip is carried out by turning the clamped sheet 180°. Inspection of the surface of the strip is carried out in good lighting. If surface defects are detected, corrective measures are taken in accordance with KD LPTs-11-3. Supervises - shift foreman, senior rolling operator, inspection operator, OKP controller.

The surface roughness parameters of the strip are measured using a portable surface roughness measuring instrument. If there are no requirements for the direction of measurement of the roughness parameter in the RD, order or current technological letters, measure the roughness parameters Ra and Pc in the transverse rolling direction on the face of the rolled product. The results of measurements of the roughness parameters of the upper (front) side are entered into the production report of the tandem mill 2000. The inspection operator, senior rolling operator controls compliance with the requirements of ND for products, technical specifications (VTI) and current technology letters.

In the absence of a portable device for determining roughness parameters, it is allowed to transfer a sample of cold-worked steel with dimensions of 100x100 mm to the laboratory of physical, mechanical and metallographic testing of the LPC-11 section with a written request from a shift foreman to determine the roughness parameters.

The surface contamination of the upper and lower sides of the rolled strip is determined by the replica method according to method M 3-TsLK-3-2198-2007. The result of determining the contamination of the upper (front) side in points is entered in the production report of the tandem mill 2000. The inspection operator, senior rolling operator controls compliance with the requirements of ND for products, technical specifications (VTI) and current technological letters. Selected replicas from the top and bottom sides are stored for 2 months from the date of production on the tandem mill 2000. The assessment (assigning a contamination score) is carried out by OKP employees.

To carry out additional control, it is allowed to carry out additional selection of strip sections on the inspection production line according to the capabilities of the tandem mill 2000 (depending on the product range being produced).

The quality of coiling of the produced rolled products must comply with the requirements of the RD for products, MMK STO, and current technological letters. The inspection operator, senior rolling operator, supervises. If a discrepancy is detected, deviations are recorded, and the rolls are sent to the insulator for further processing.

If a discrepancy is detected, the previous rolls before sampling are marked by the OKP inspector in the transfer passport with a special symbol “X” with a description of the discrepancy.

The cut sample is removed from the table of guillotine shears using a gripping device. The cut sample is cut into specific geometric dimensions using guillotine shears at the UPiNO site by a sample cutter.

After quality control of the manufactured product is carried out, a sample 7 m long is cut using guillotine shears of an in-line strip inspection unit into technological trim.

1 .6 Lubrication of drive units of cold rolling mill 2000

Lubrication is the action of a lubricant located between the rubbing surfaces.

Lubricants serve to reduce friction and wear of machine parts. Their use also reduces energy consumption and ensures reliable operation of the equipment for a long time. The lubricant completely or partially separates the rubbing surfaces from each other. In this case, the dry friction of the contacting parts of the mechanism is replaced by one of the types of liquid friction, in which direct contact between the parts of the assembly is eliminated or reduced. At the same time, the lubricant protects rubbing surfaces from corrosion, and when using liquid oils, removes excess heat from them, preventing overheating of machine components.

For lubrication of friction units rental equipment Depending on their operating conditions and design features, liquid, thick (consistent) and solid lubricants are used. The vast majority of them are petroleum products. In some cases, to improve the performance qualities of lubricants, animal or vegetable fats or special alloying substances are added to them in small quantities, improving certain properties of lubricants.

Liquid lubricants (mineral oils) are widely used to lubricate the main and auxiliary equipment of rolling shops. Its great advantage is the ability to continuously lubricate friction units of machines with the same lubricating oil for a long time.

At the same time, it not only lubricates the rubbing parts of the unit, but also removes wear products, dirt and other harmful exceptions. The main properties of oils that serve as criteria for their selection for lubrication of rolling shop equipment: viscosity, lubricity (lubricity), flash point and pour point, acidity, as well as the content of mechanical impurities. The type of oil for lubricating friction units is selected based on their operating conditions (loads, speeds, temperature conditions), properties of the lubricant and features of the lubrication system.

In general, the greater the load on the rubbing surfaces and the temperature of the assembly, the higher the oil viscosity should be.

Thick (grease) lubricants in rolling shops are used to lubricate machine components mounted on rolling bearings, plain bearings with low shaft rotation, articulated joints, low-speed gears, guides and all other friction units of machines. When the use of liquid oils is not beneficial for design or economic reasons. Grease lubricants protect the working surfaces of parts much better from the penetration of dust and moisture and do not require such expensive seals to seal friction units.

The influence of the physicochemical properties of greases on their performance is similar to the influence of similar properties on the quality of mineral oils.

Solid lubricants, used in the form of briquettes in rolling production, are used mainly to lubricate the open journals of the rolls of thin-sheet mills, which heat up to 2500 and above during operation.

Typically, briquettes are a fused mixture of fresh and waste petroleum bitumen 5 in a ratio of 1: 1 to 1: 4 with small additions of 1-2% solid antifriction filler (fine flake graphite, talc). Sometimes pure petroleum pitch or rubrax is added to the composition of briquettes to improve lubricity. Briquettes are placed directly on the necks of rolling rolls. Influenced high temperature The briquette mass melts and covers the journals and bearing shells, lubricating them.

It should be noted that the presence of mechanical impurities in grease lubricants is more dangerous than in oils, since due to the higher density of lubricants, impurities are less easily removed by filters and, therefore, fall between the friction surfaces, causing their wear.

Purpose of systems:

reduction of the coefficient of external friction during cold rolling;

removal of heat generated during the rolling process;

regulation of the thermal profile of the rolls;

obtaining strips with surface quality that meets the requirements of standards and technical specifications.

Requirements for the emulsion:

no delamination;

absence of toxic compounds;

the ability to remove residual emulsion products on the strip during the annealing process.

Preparation of an emulsion based on emulsols "Kvekerol-1914", "Rinol-1" and similar ones involves mixing the emulsol with chemically purified water or condensate.

The operating temperature of the emulsion is 40-58. The temperature of the emulsion is constantly monitored by the senior roller according to the readings of a digital thermometer.

The fat content of the emulsion (mass fraction of total oils in the emulsion) and the temperature of the emulsion are reflected monthly by the senior roller in the production book.

The temperature regime of the rolls is regulated by the amount of emulsion supplied to the roll barrels. When the mill stops, the emulsion supply stops, but the emulsion continues to circulate through the internal emulsion cycle.

To protect the emulsion from contamination, if necessary, wash cages, wires, rolls, cushions, rolls hot water, before flushing the equipment, it is necessary to switch the pumped systems to drainage. During preventive maintenance, the mill is thoroughly cleaned, pipelines, crankcases and manifolds, and emulsion tanks are flushed. An aqueous solution with a mass fraction of calcined salt of 2-4% or detergents that do not contain phosphates are used as a washing solution. The solution temperature should be 40-60.

After washing with a cleaning solution, all equipment and the emulsion system are washed with hot water. After washing all the equipment, the washing solution is supplied through the drainage system to the oil emulsion wastewater regeneration unit and purified according to TI - 101-P-HL-8-321-2004.

1 . 7 Occupational health and safety during the operation of a cold rolling mill 2000

The employee’s labor responsibilities related directly to the labor function include, among other things, the responsibilities provided for in Art. 211 of the Labor Code of the Russian Federation - obligations to comply with legal and labor protection requirements individuals when carrying out any type of activity. Consequently, violation of labor protection rules can be classified as a disciplinary offense.

Responsibilities for ensuring safe conditions and labor protection in the organization rest with the employer. The list of these responsibilities is given in Art. 212 TK.

Furthermore, in accordance with Art. 212 of the Labor Code of the Russian Federation, the employer is obliged to ensure that persons who have not undergone training and instructions on labor protection, internship and knowledge testing of labor protection requirements are not admitted to work.

The employer should remember that an employee cannot be considered guilty of violating labor protection requirements with which he was not familiar. The employer’s obligation to provide instructions on labor protection, organize training in safe methods and techniques for performing work and providing first aid to victims with all employees of the organization, including the manager, is enshrined in Art. 225 Labor Code of the Russian Federation. If the employer has not fulfilled this obligation, he has no basis for concluding that the employee is guilty; Moreover, he himself may be held accountable for failure to fulfill this obligation.

All persons hired undergo induction training in accordance with the established procedure. It is carried out by a labor protection specialist or an employee who is assigned these responsibilities by order of the employer. In addition to introductory briefing on labor protection, primary briefing is carried out at the workplace, repeated, unscheduled and targeted briefing.

Conducting labor safety briefings includes familiarizing workers with existing dangerous or harmful production factors, studying labor safety requirements contained in local regulations organization, labor protection instructions, technical and operational documentation, as well as the use of safe work methods and techniques.

The labor safety briefing ends with an oral assessment of the employee’s acquired knowledge and skills in safe work practices by the person conducting the briefing.

Induction training .

All those applying for work before imprisonment employment contract must undergo induction training on labor protection and fire safety training.

Introductory training is carried out with all newly hired employees, regardless of their education, work experience in a given profession or position, with temporary workers, business travelers, students and students arriving for on-the-job training or practice.

Induction training in the organization is carried out by a labor protection engineer or a person entrusted with these responsibilities. In accordance with Federal Law No. 90-FZ dated June 30, 2006, if the number of people in an organization is less than 50 people and if there are no staffing table Positions of labor protection engineer The duties of a labor protection engineer are assigned to one of the enterprise employees.

Introductory training is carried out in a labor protection office or a specially equipped room using modern technical training aids and visual aids (posters, exhibits, models, films, videos, etc.).

To conduct introductory training, a program and instructions are developed taking into account the specifics of your production, which are approved by the employer of the organization.

Introductory training can be carried out individually or with a group of incoming employees. An entry about the induction training is made in the induction training logbook with the obligatory signature of the person being instructed and the person instructing, as well as in the employment documents. Along with the magazine, a personal training card can be used.

Initial training at the workplace is carried out before the start of production activities: with all newly hired workers in the unit, including employees performing work under the terms of an employment contract concluded for a period of up to two months or for the period of performance seasonal work, in their free time from their main job (part-time workers), as well as at home (homeworkers) using materials, tools and mechanisms provided by the employer or purchased by them at their own expense; with employees of the organization transferred in accordance with the established procedure from another structural unit, or employees who are entrusted with performing work that is new to them; with seconded employees of third-party organizations; with builders performing construction and installation work on the territory of an existing enterprise; with students and students educational institutions relevant levels, undergoing practical training (practical classes), and other persons participating in the production activities of the organization.

Persons who are not involved in the maintenance, testing, adjustment and repair of equipment, the use of tools, the storage and use of raw materials and materials do not undergo initial training at the workplace. The list of professions and positions of workers exempt from initial instruction at the workplace is compiled on the basis of Resolution of the Ministry of Labor of Russia and the Ministry of Education of Russia dated January 13, 2003 N 1/29 “On approval of the Procedure for training in labor protection and testing knowledge of labor protection requirements for employees of the organization.”

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course work, added 04/27/2011


Analysis of the "electric drive-working machine" system of a cold rolling mill. Load diagram, choice of electric motor. Calculation and verification of the correctness of transient processes in an electric drive during an operating cycle, construction of an electrical circuit diagram.

course work, added 11/04/2010


The role and tasks of cold rolling of metal. Detailed analysis of the technical process of cold-rolled sheet production. Characteristics of bell furnaces. Operating principles of training mills. Control devices used in rolled steel production.

practice report, added 06/25/2014


Specifics of management at ferrous metallurgy enterprises with a full production cycle. Functions and structure of automated control systems of the 630 cold rolling mill. Design and principles of operation of the local automatic control system SARTiN.

test, added 01/17/2010


The concept and structure of cold rolling rolls, their purpose and requirements. Criteria for selecting forging equipment and initial ingot. Characteristics of the equipment of workshop areas. Production of cold rolling rolls at Ormeto-Yumz.

course work, added 05/04/2010


Selection of steel for workpieces, rolling method, main and auxiliary equipment, lifting and transport vehicles. Technology of rolling and heating of workpieces before it. Calculation of roll calibration for rolling round steel for files and rasps.

course work, added 04/13/2012


Scheme of metal deformation on roller mills for cold rolling of pipes, its analogy to cold rolling of pipes on roller mills. Design of roller mills. Technological process for the production of pipes in cold rolling mills. Types and sizes of rollers.

abstract, added 04/14/2015


Characteristics of the production of cold-rolled sheets. Initial billet and its preparation for rolling, types of cold rolling mills. Technology for the production of carbon steel sheets, types of defects and their prevention, technical and economic indicators.

course work, added 12/17/2009


Development of a project for a reversible single-stand cold rolling mill with a capacity of 500 thousand tons per year in the conditions of CherMK OJSC Severstal for the purpose of producing cold-rolled strip from low-carbon and high-strength low-alloy steels.

Comparing two identical steel samples obtained different ways, it is impossible to say for sure which one is better. But taking into account the specifics of the use of metal products (be it sheet or rod), in each specific case it is necessary to understand what properties the alloy acquires during a particular rolling of blanks (“slabs”). This is necessary not only in order to make the best choice and not overpay for products (especially if a large batch is purchased).

Sometimes the difference between hot-rolled and cold-rolled products is fundamental.

The information presented in this article will be of interest to the average consumer and will definitely help to make the right decision. But it is also worthwhile for a professional to familiarize himself with the proposed material, since it is always useful to periodically refresh his memory.

The main difference in rolling methods is the temperature at which the workpieces are processed. When hot it exceeds 920 ºC (1700 ºF). Cold rolling is carried out in a more gentle mode, and the temperature is significantly lower than the value (sometimes at room level) at which recrystallization of a particular metal (alloy) occurs.

Note

Recrystallization is a process in which equiaxed grains (granules) form and grow. Occurs with a significant increase in temperature and changes the structure of the material, which acquires different properties.

Rental features

Hot

• Metal (alloy) is easier to process, so this rolling method can produce thinner sheets or rods of smaller cross-section.
• For the manufacture of products using the hot rolling method, low-grade, cheaper steel is mainly used.
• There is a need for further processing of products, since they are often covered with scale.
• The geometry of hot-rolled samples does not differ in rigor (for example, unevenness at the corners of sheets, uneven thickness), since it is impossible to accurately calculate the limits of deformation when cooling the metal.

Calculation of the mass of hot-rolled and cold-rolled sheets according to GOST 19903-90, 19904-90:

• Reinforcing (strengthening).
• Bearing (foundation).

Cold

• This method of rolling allows you to accurately maintain the specified dimensions of products.
• The surface of the resulting samples is smoother and more even, so their subsequent processing is reduced to a minimum (and sometimes not required at all).
• Cold-rolled metal becomes harder and stronger (for bending, tensile, tearing) with a uniform structure over the entire area.
• Going into production.
• The higher quality of cold-rolled steel increases its cost.

Conclusion

If the cost of rental comes first, then preference should be given to hot. When is the determining factor appearance, strength, quality, then you should purchase cold-rolled samples.