During the Ninth Five-Year Plan, two 2000 mills were installed at Novolipetsk and Cherepovets metallurgical plants(1975). The mills are designed to consume the cast initial slab coming from the continuous caster. They take into account shortcomings in the design of equipment and the technological process that appeared during the operation of mills 1700.
Wide-band continuous hot rolling mill 2000 of the Novolipetsk Metallurgical Plant designed for rolling sheet steel with a thickness of 1.2-16 and a width of 900-1850 mm from a sheet slab supplied from a continuous caster, with dimensions of 170-250X900-1850X4800-10500 mm and a weight of up to 36 tons.
The technological rolling process and the composition of the mill equipment are as follows. The slabs obtained from the continuous caster are stored, inspected and cleaned. Then the slabs are fed into heating furnaces - five-zone, methodical, with end task and output, double-sided heating, equipped with control and measuring equipment for automatic regulation of the metal heating process. The ovens are connected to each other by roller tables.
The mill is equipped with roughing descalers: the first with a vertical roll, the second with a horizontal roll arrangement. The roughing group consists of four universal four-roll stands. Practice has shown that it is necessary to remove surface defects on cast slabs after destruction of the cast structure, therefore an in-line fire cleaning machine is installed after the first universal stand. The finishing group includes shears, a finishing descaler and seven four-roll stands. Depending on the thickness, the finished profile is wound into rolls on differentiated winders. The diameter of the working rolling rolls in the roughing group of the mill is 1200, in the finishing group 800 mm; support (in both groups) - 1600 mm. The length of the roll barrel is 2000, and in the rough descaling machine with vertical rolls it is 800 mm.
With a maximum rolling speed of 20 m/s and a possible increase to 22 m/s, the mill can provide an annual productivity of 6 million tons. The weight of the equipment installed on the mill is 38 thousand tons, the power of the main electric motors is 119 thousand kW.
The continuous wide-band hot rolling mill 2000, installed at the Cherepovets Metallurgical Plant, is similar in its equipment composition, assortment of slabs and finished sheets to that discussed above.
However, the design separate equipment and its location, a number of significant changes have been made, which is advisable to consider (without a mill diagram).
This mill was the first to install heating furnaces with walking beams; the possibility of planting hot slabs in the furnace is provided. Fuel - natural gas calorie content 8500 kcal/m3. The productivity of one furnace (there are four according to the project) is 400 t/h when loading cold slabs. The duration of heating the slabs to a temperature of 1200-1250° C is on average about 3 hours.
In a rough descaler with vertical rolls, the heated slabs are compressed in width. The purpose of compression (D/g "50 mm) is to reduce the standard sizes of slabs and destroy the scale layer, which is knocked down by water at a pressure of 110-130 atm. In the subsequent two-roll stand with horizontal rolls, also after rolling, scale is hydrolyzed at compression D/g = 50-^60 mm.
Then four roughing universal four-roll stands are arranged in succession, of which the last three form a continuous group, the creation of which makes it possible to reduce the decrease in the temperature of the rolls and reduce the length of the mill. Engines DC continuous group stands make it possible to regulate the rolling speed over a wide range depending on the cross-section of the rolls, the amount of reduction and the temperature of the rolled metal. Here, it is more possible to roll with acceleration, which was first used at mill 2000 of the Novolipetsk Metallurgical Plant.
The temperature of the rolls before the finishing group of stands is 1000-1150° C. The front and rear ends of the strips are cut using flying shears before being fed into the finishing group.
Behind the finishing descaler and behind the first three to four finishing stands, scale is removed with high-pressure water. Hydrobeating is also used to reduce the rolling temperature when rolling thick sheets. To equalize the temperature along the length of the roll, rolling in a continuous finishing group of stands is carried out with an acceleration approximately equal to 0.05-1.0 m/s2.
The speed regime in the finishing stands can be different: rolling at a lower speed than the speed of threading the strip into the coiler is carried out G accelerated along the entire length of the strip; with a larger one, it changes from a constant filling when the strip is captured by the coiler (~ 10 m/s) to maximum (21 m/s) (in this case, the finishing stands accelerate together with the coiler). Finishing stand motors are DC and multi-armature. The temperature at the end of rolling of sheet steel profiles of all thicknesses is in the range of 830-900° C.
On the outlet roller table behind the finishing group of stands, the strips are cooled with water at a speed of 6-50 ° C/s. The amount of cooling water is regulated depending on the cross-sectional dimensions of the finished product, its temperature, steel grade, speed of the moving product and can reach 14.0 thousand m3/h. The temperature of the strip before rolling is 500-600° C.
Behind the mill there are two groups of winders, three in each; the first - for strips with a thickness of 1.2-8 mm, is located approximately 100 m from the finishing stand; the second - for strips with a thickness of 4-16 mm is located at a distance of 250 m from the finishing stand. Finished products can be supplied in rolls and sheets. Mill productivity: 300-1270 t/h (depending on the cross-section of the rolled sheets); annual productivity is approximately 6 million tons. The mill has complex automation all operations of the technological process, including finishing of rolled products.
The mill has four methodical heating double-row furnaces, with end task and slab delivery and double-sided heating. The mill is equipped with seven rolling stands, the first of which is a descaling stand with vertical rolls, the second is a two-roll reversible roughing stand. On the metal flow line there are shears for trimming the front and rear ends of the rolled material with a cutting force of 350 tf. A descaling descaler is also installed in front of the finishing group of stands - a two-roll stand with a work roll diameter of 360-410 and a barrel length of 840 mm. The finishing group consists of five four-roll stands driven by individual electric motors. Working diameter: rolls 490-525, support rolls 916-1040 mm, length 813 mm. Behind the finishing group there are two winders with tippers for winding the pellets into rolls and transferring them to the conveyor.
The technological process of rolling on this mill is relatively simple and in many ways similar to that discussed above on continuous mills. The slabs heated in furnaces to a temperature of 1250 ° C are supplied to the rough descaling machine (work roll diameter 670-724, barrel length 200 mm), which carries out; compression of the side edges, destroying the surface layer; scale while simultaneously shaping the slab width. Next, the slab is rolled in a roughing reversible stand according to two schemes: if its width is insufficient, in the transverse direction, and then, after turning in the horizontal plane, in the longitudinal direction. If the width of the slab corresponds to the specified width of the sheet, the slab is rolled in 5-9 passes to the specified thickness and? transferred to the finishing group of stands. The temperature of the end of rolling on the roughing stand is 1100° C. j Rolling in the finishing group of stands begins at > 1050 and ends at 900° C. The rolling speed in the roughing reversible stand is 3.82-6.0 m/s; in finishing stands upon exit of the rolled product from the rolls 4.1 -:i 8.2 m/s.
The finished sheet steel is wound into rolls and transferred to perform the appropriate finishing and technological operations.
The increase in the production of hot-rolled sheet steel in the coming years will be largely ensured by the construction of new continuous mills with a roll barrel length of 2000 mm or more with a productivity of 4-7 million tons per year. - When creating new and improving existing continuous hot rolling mills, the following important technical and technological issues will be resolved:
1) mastering the rolling of sheets with a thickness of 1-1.2 to 20, a width of up to 2000 mm or more from continuously cast slabs weighing 50-60 tons;
2) the use of heating furnaces with walking beams;
3) increasing the rolling speed to 25-30 m/s;
4) creation of continuous roughing groups from universal four-roll stands;
5) creation of continuous finishing groups consisting of 7-8 and four-roll stands equipped with devices for elastic anti-bending of rolls;
6) widespread introduction of automatic control of strip sizes during the rolling process;
7) the use of water removal of scale from the rolled metal with water pressure up to 150-180 at;
8) introduction of technological lubrication during rolling.
Primetals Technologies was the first company in the world to develop a slab calibration press and remains a leader in this field to this day. Based on our rich experience, we have made significant changes in the design of the slab calibration press, which has resulted in
- further reduction in width: max. 350 mm
- increasing the productivity of the slab continuous caster,
- increase in yield,
- as well as design development to reduce the amount of time required for modernization (or installation)
Improved Intermediate Rewinder
The coilbox is installed between the roughing and finishing stands to rewind the material after the roughing stands. Installing such a coiler allows you to reduce the distance between the roughing and finishing groups on a new mill and minimize the drop in the temperature of the rolled product supplied to the finishing group. In addition, the drumless rewinder also does not allow a significant drop in temperature on the internal turns of the roll compared to a drum rewinder. The drumless rewinder also has space for installing side heat shields, which help prevent temperature drop at the roll edges. The winder, developed by Primetals Technologies, has two operating modes. One of them is passive, when no active mechanical actions are performed - this is a simple method of work. The second operating mode is the forced roll transfer mode. The boost mode system ensures fast and reliable bale transfer and has higher productivity.
- Prevention of temperature drop on the internal turns of the roll when using a drumless rewinding device
- Prevents temperature drop at the roll edges thanks to adjustable side heat shields
- Increased productivity thanks to short winding, which is achieved thanks to increased speed winding and forced transfer of the roll from the winding position to the unwinding position
- Stable operation of the finishing group is ensured due to the uniform temperature distribution along the entire length of the roll. Thanks to this, rolling with acceleration in the finishing group is not required
- A mode of passing through a rewinder without winding is possible, if there are appropriate requirements for productivity and production method
- The rewinder can be used for a wide range of roll sizes when producing a wide range of carbon and stainless steels
Edge trimmers with different drum rotation speeds
After leaving the roughing group, the ends of the rolled product are formed in the head and tail parts in the form of the so-called “tongue” and “fish tail”. Edge trimmers are installed in front of the finishing group to trim the ends of the strip to ensure reliable threading of the strip. Disc edgers with different drum rotation speeds from Primetals Technologies are a unique tool. The shears consist of an upper and lower drum of different diameters with different linear speeds. During rotation, the position of the knives relative to each other alternately changes (positions “plus” - “zero” - “minus”), which gives a number of operational and economic advantages.
- Thanks to alternate changes in the positions of the knives relative to each other, an improved profile of the ends of the roll is formed
- Reduced wear and increased blade clearance increases blade life
- Possibility of cutting edges with minimum tolerances of at least 20 mm. This function, together with the optimization system, allows you to radically reduce the amount of trimming losses.
- Robust design and high torsional rigidity due to the use of synchronizing devices at the ends of the drum shafts between the upper and lower parts
- Quick blade change using hydraulic release system (optional)
- Quick drum change (optional)
Pair Cross Cage
Primetals Technologies is the first company in the world to develop a horizontal cross-roll mill, which offers many possibilities for controlling the cross-sectional profile of the strip. To this day, we maintain a leading position in this area, in addition, Primetals Technologies, using all its extensive experience in metallurgy, has developed a number of improvements to this system.
- Strip shape control
- Simplified design
- Achieving high compression ratios
- Reduction of mill vibrations thanks to the use of stand stabilization device (MSD)
SmartCrown rollers
SmartCrown work rolls provide a modified sinusoidal contour. By choosing the correct contour coefficients and making the axial shift of the work rolls the same distance in opposite directions, the result is always a cosine shape of the roll gap, regardless of the actual shift position of the rolls.
Cages with axial shift of work rolls
Primetals Technologies pioneered the development of the axial work roll stand and continues to be a leader in this field and has greatly improved the technology based on our extensive experience in the metallurgical industry. Primetals Technologies uses axial displacement of work rolls in the production of hot strip to perform two tasks:
- Even distribution of work roll wear
- Strip flatness adjustment (SmartCrown), see detailed description below:
Cage stabilization device (MSD)
In difficult realities today Maintaining stable operation of a rolling mill is becoming an increasingly difficult task. The cage stabilization device is a hydraulic cylinder installed in the frame opening and pressing the roll pads with constant force. The device allows you to remove the gap between the roller pads and the frame, supports the rollers in the correct position and stabilizes them.
- Ensures stable rolling in difficult conditions
- Stabilizes strip filling
- Reduces the amount of work required to regulate the roll gap in the bed opening (simplifying maintenance)
- Prevents problems caused by misalignment of work and support rolls
- Possibility of installation on an existing mill
In-line roll profiling device (ORP)
Primetals Technologies pioneered the development of in-line roll grinding and remains a leader in this field to this day, and we have significantly improved the technology based on our extensive experience in the metallurgy industry.
- Increased roll life
- Elimination of roll surface defects
- Increasing the rolling length of a product of the same width
- Possibility of switching to larger widths without reloading the rolls
Loop holder profiler (LSM)
Measuring the strip profile between mill stands has always been difficult and extremely unreliable. Primetals Technologies has developed a looper profilometer to provide continuous and accurate measurement of sheet geometry between stands. The LSM profilometer has a number of advantages:
- The load on the segment rollers is measured using a torque sensor without taking into account the influence of hysteresis, in contrast to the method when a load cell is used
- Measuring with a torque sensor gives higher accuracy and increases reliability without influences caused by changing mechanical conditions
- Easy to replace on existing loop holders. Since the profilometer has a low moment of inertia, it is possible to use the existing drive system of the loop holder
- Easy to replace segment rollers during maintenance
Power Cooling. Enhanced strip cooling system
Hot rolling mills are often limited in their production capabilities, namely the capacity and flexibility to produce advanced high strength steel grades (AHSS), such as API X80/X100, dual-phase, martensitic and multi-phase grades.
. Therefore, Primetals Technologies has developed Power Cooling technology, designed for cooling and special metallurgical processing of rolled products “in line”. This technology combines the benefits of traditional laminar cooling or “low pressure cooling” and “high pressure cooling” with the highest cooling rates, resulting in greater operational variability.
Equipment. Enhanced Cooling Technology
Enhanced cooling technology can be used in the initial stages of cooling, in the area between the roughing and finishing group, between the stands of the finishing group and finally in the cooling section on the roller table. Various cooling modes can be configured as shown in the diagram below. The Power Cooling unit can be installed on existing units using the existing water treatment plant, tank and piping. The water supply to the Power Cooling installation is carried out through a booster pump, which creates the necessary operating pressure. The second operating option, that is, operating in laminar cooling mode, involves bypassing the pump and supplying water directly to the collectors of the enhanced cooling system from the pressure tank. Thus, after installing an enhanced cooling system, it is also possible to use laminar cooling along the entire cooled length of the strip
Application
The use of enhanced cooling is not limited to thick strips (> 18 mm), which require greater cooling intensity. Thanks to the advanced function of regulating water flow and therefore regulating heat transfer, this system also used for strips where the combination of strip thickness, rolling speed and cooling intensity requirements is particularly important. In addition, Power Cooling is used for the production of standard steel grades, since this technology can be used in laminar mode. The combination of Power Cooling and laminar cooling is an ideal solution for cooling lines. The application of this system is very wide, since it allows you to optimize both the current assortment and adjust the operation of equipment to future requirements.
Typical characteristics of Power Cooling technology
- Significant increase in cooling intensity compared to laminar/turbolaminar cooling
- High heat transfer coefficient up to 5 MW/m²
- Wide flow control range for maximum metallurgical flexibility
Alloying
Power cooling provides the opportunity to reduce alloying costs by allowing the replacement of strengthening additives by strengthening due to higher cooling intensity.
Advantages
Power Cooling from Primetals is a modern strip cooling technology
- Provides exceptionally high cooling rates (up to 40K/s for 25.4mm)
- Wide control range - from 10% to 100%
- Application for all units of the range, since operation in two modes is possible - laminar and enhanced Power Cooling
- Installed on both existing and new mills in combination with laminar cooling for coil cooling or in the interstand cooling zone
- Ideal solution for two-stage cooling, which is required, for example, for dual-phase steels
- Suitable for increasing the capacity of short cooling lines
Improved winder model
Primetals Technologies offers a winder whose design features include updates based on our experience.
- Wedge-shaped rocker drum with stepless sliding mandrel, providing excellent winding quality and high reliability
- Modular design allows for quick drum replacement
- Automatic roller run-out control prevents marks from forming on the first internal turns of the roll
- Precise adjustment of side guides and pinch rollers ensures stable operation and roll quality
It has been 30 years since Polish specialists began building the “2000” hot rolling mill in the sheet rolling shop No. 10 of OJSC MMK. The history of this technological complex is quite unusual.
In the mid-70s of the last century, equipment from the 2000 wide-band hot rolling mill was manufactured in the Soviet Union and sent to the Polish People's Republic. It was planned to be included in the complex of the Katowice metallurgical plant. But due to the political crisis in the republic, construction was stopped. And on July 25, 1985, a resolution of the Council of Ministers was issued on the re-export of equipment from the 2000 hot rolling mill for the Magnitogorsk Iron and Steel Works.
In March 1986, by order of MMK director Ivan Romazan, the removal of slag from the construction site of the 2000 mill was organized. In 1987, the first Polish builders arrived in Magnitogorsk. These were experienced specialists who built many important facilities in their homeland. In Magnitogorsk, the first thing they did was build residential buildings, social and technical facilities for Polish workers. The newspaper "Magnitogorsk Worker" for September 1987 reports: "...Polish builders plan to build 40 thousand square meters of total living space in the city. In addition to residential buildings, a canteen, a clinic, two clubs, shops, and a consumer service point will soon appear here."
Meanwhile, Polish workers continued to arrive to build Mill 2000. In 1988, equipment began to arrive from Poland. The builders were interested in ensuring that all structural elements were delivered on time. Over the course of a month, almost four hundred wagons from Poland with structures, equipment, building materials, and everything necessary for living and working were unloaded.
In 1989, the installation of the first overhead cranes began in the cast slab receiving department. The following year, installation of heating furnace No. 1 and furnace section equipment began. Already in August 1990, Ivan Romazan issued an order to recruit a group of qualified workers - technologists from operating rolling shops for training at the "2000" hot rolling mill of the Cherepovets Metallurgical Plant.
The economic crisis of 1992 affected the financing and supply of construction with everything necessary. Difficulties arose in preparing rolls for the mill. Senior foreman Yuri Nosenko recalls: “The roll grinding department was not ready. Fluid friction bearings, roll pads - everything was mothballed.”
By 1994 the situation had returned to normal. So, on October 8, at 11:50 a.m., the first hot-rolled coil measuring 7x1100 millimeters was rolled at the 2000 mill. This date is considered the birthday of sheet rolling shop No. 10. And the hot rolling mill “2000” became the first large industrial facility at MMK, built with the help of foreign builders and specialists.
In the mid-2000s, the unit was reconstructed. As part of the modernization, a fourth heating furnace was built, the mechanical equipment of the mill was updated, which made it possible to produce a thicker range. In addition, new technologies were introduced that made it possible to switch to a fully automated mill control mode.
In 2016, the 2000 hot rolling mill produced more than five million tons of hot rolled products. This is the highest figure for the entire period of operation of the mill.
Today the hot rolling mill "2000" is one of the most powerful and modern in Russia. The equipment allows rolling all currently existing steel grades. The range of products produced here is very wide. The range of applications is also diverse - pipe production, construction industry, mechanical engineering. Marine and structural steel grades and transformer steel are rolled here.
The camp "2000" can be safely called a symbol of Soviet-Polish friendship, which cemented international ties with the Polish Republic.
Olga Ryzhkina, chief archivist of the city archive.
Exercise
Complete the design of the main line of working stand No. 6 of hot rolling mill 2000.
Determine the purpose and give a brief description of the 2000 hot rolling mill LPTs-10, which includes the designed main line of the working stand.
Select equipment and main parameters of the designed main rolling stand line.
When designing the main work cage line, perform, determine or assign the following:
material, design and dimensions of rolls; force effects on the rolls; calculation of roll strength; calculation of the rigidity coefficient of the roll system;
type, design and main parameters of rolling roll bearings;
type and design of devices for installing and balancing rolls; calculation of the pressing mechanism;
type, design and dimensions of the frame and its elements; calculation of the strength and rigidity of the frame;
calculation of the rigidity coefficient of the working stand;
fastening the working cage to the foundation;
type and design of roll reinforcement;
select the type and design of transmission mechanisms of the main line of the rolling stand;
select the type and determine the power of the main drive of the stand;
select the type and design of devices for transferring rolls and describe the transfer method.
Introduction
Hot-rolled sheets are produced in continuous and semi-continuous wide strip hot rolling mills (approximately 3/4 of total production), strip mills with coilers in furnaces, planetary and plate mills. Currently the most in an efficient way production of hot-rolled sheets and strips is Rolling is carried out in continuous and semi-continuous mills. These mills also produce rolled stock for cold rolling mills. Modern wide-band hot rolling mills are designed for rolling strips of a wide range (thickness from 0.8-1.2 to 16-25 mm, width 600-2300 mm). The mass of rolled slabs is up to 6-7 million tons/year. Continuous hot rolling mills consist of two trains carefully located groups of cages. In a draft group consisting of four three to five stands with horizontal and three to four stands with vertical rolls, the strip is alternately rolled in each of the stands. It is possible for the strip to be simultaneously located in adjacent stands with zontal and vertical rollers. In the finishing group, the strip is simultaneously It is located in all or several cells. The roughing group usually consists of quarto stands, which ensures minimal variation in thickness during rolling, and includes rough scale duo breaker and expansion cage. All stands are located in succession erally and have an individual drive. The finishing group consists of six to seven quarto stands and a finishing descaler. The cages are equipped with loop holders, between them they are installed on ruling cells. The finishing group includes a flying knife bits for cutting the ends of rolled products. In this work, the experience of the conditions of stand No. 6 of the 2000 wide strip hot rolling mill is studied and generalized. 1. Purpose and brief characteristics of the mill
.1 Purpose of the mill
Continuous wide strip hot rolling mill 2000 is designed for the production of hot-rolled strips from carbon and low-alloy steel grades, respectively, with a cold strength of up to 640 N/mm2 and 750 N/mm2, thickness 1.2 - 16.0 mm and width 750-1850 mm, rolled into rolls weighing up to 45 tons. Rolling of strips of low-alloy steel grades is carried out at reduced conditions within the limits of the static loads on the mechanisms of the main lines of the working stands allowed by the design. .2 Characteristics finished products:
Hot rolled strip sizes thickness, mm1.2 - 16.0; width, mm750 - 1850; internal diameter of the roll, mm850; maximum outer diameter of rolls, mm 2300; weight of rolls, tons no more than 45 The mill equipment, together with complex automation systems purchased from General Electric, USA, must ensure the production of products that meet the requirements specified in Table 1.1. Table 1.1 Parameter name Permissible deviation Note Strip thickness, mm 1.2 - 5 5.1 - 10 10.1 - 16±0.05 mm ±1% of the specified value ±0.1 mmAt 96% of the length2. Variation in strip thickness with width, mm up to 1250 1251 - 1650 1651 - 1850±0.03 mm ±0.04 mm ±0.05 mmAt 96% of the length3. Strip width, mm 750 - 1850±6 mmAt 96% of the length4. Flatbed capacity 5 mm/1 m5. Roll telescopicity 50 mm6. Crescent strip 5 mm/3 m 1.3 Characteristics of the original workpiece
The starting material for rolling at NShS-2000, as a rule, is cast slabs coming from continuous steel casting plants through the transport and finishing department. Slabs prepared for rolling must comply technical specifications for cast billet TU-14-1-3347-82. The mill is supposed to use hot loading of slabs into heating furnaces while preserving their heat in specially created storage tanks. The share of hot planting is 80%. The temperature of the slabs during planting in the furnace is on average about +750°C. Dimensions of initial blanks (slabs): thickness, mm 250; width, mm 750 - 1900; length, mm 6000 - 12000; weight, t, no more than 45. 1.4 Mill productivity
According to the design, the mill's productivity for hot-rolled coils is: 0 million t/y - when working with 3 heating furnaces; 5 million t/y - when working with 4 heating furnaces. The annual equipment operating hours are assumed to be 7000 hours. .5 Brief technical characteristics of the main equipment of the mill
The equipment layout is shown in Figure 1 Heating furnace area: ) Number of furnaces with walking beams, pcs. 3 (4). ) Maximum furnace productivity, t/h 465. ) Weight of the charge in the furnace, t, no more than 1400. ) Temperature in the oven, °C, no more than 1380. Draft group: ) Number of stands, pcs. 7 Including: vertical cage (scale breaker), pcs. 1. duo cage No. 1, pcs. 1. universal quarto stands No. 2, 3. (free-standing), pcs. 2. universal quarto stands No. 4, 5, 6. (as part of a continuous group), pcs. 3. ) Roll diameters, mm. vertical stand 1200/1100. duo cage No. 1 1400/1300. universal stands No. 2 - 6: workers 1180/1080. reference 1600/1460. vertical 1000/900. ) Maximum rolling speed, m/s 2 -5. Finishing group: ) Number of stands, pcs. 7 (8). ) Roll diameter, mm: workers (stands No. 7, 8) 850/810. workers (stands No. 9 - 13) 800/760. reference 1600/1460. ) Roll length, mm: 2000 workers. reference 1820. The length of the work rolls of the last four stands, equipped with a system of axial shifting of the work rolls, is given in the technical specifications of the equipment supplied by Davey McKee. ) Maximum rolling speed, m/s 21 (23). ) Type of pressure device is combined hydro-electronic. ) Mechanism for axial movement of work rolls (on the last 4 stands). ) Rolling level mark, m +0.975. ) Deviation of rolling level, mm ±5. Cleaning group: ) Number of cooling sections, pcs. 2. ) Number of winders for strip: thin, pcs. 2 (3). thick, pcs. 3. Figure 1 - Layout plan for continuous strip mill equipment Characteristics of some energy carriers: ) Electricity: DC voltage, V 220. voltage AC, B 380. ) Hot water, technological: temperature in the supply pipeline, °C 70. pressure in the supply pipeline, MPa 0.3. ) Process water: pressure, MPa 0.3. temperature, °C from +5 to +20. concentration of suspended matter, mg/l, not more than 100. particle size, mm, no more than 0.3. hardness, mg.eq/l 6 - 7. oil concentration, mg/l, no more than 20. ) Compressed air, dried: consumer pressure, MPa 0.4 - 0.6. pressure at the entrance to the workshop, MPa 0.6 - 0.9. 2. Selection of the block diagram of the main line of the working stand
The drive of the work rolls of the mill 2000 stands is carried out by an electric motor through intermediate transmission mechanisms and devices that make up the working line of the stand. The transmission mechanism in stand No. 6 is a gearless drive through the main spindle, gear cage and spindles. With a gearless drive, the electric motor is connected directly to the gear cage by the main spindle (Figure 2). Gear stands are used to transmit torque from a motor or gearbox to spindles and work rolls. Figure 2 - Block diagram main line of the working stand: 1 - support rolls, 2 - work rolls, 3 - universal spindles, 4 - balancing mechanism, 5 - gear stand, 6 - motor coupling From the condition for choosing the optimal values of the spindle angle when transmitting the required torque in the roughing group of stands, three standard sizes of gear stands with center-to-center distances were adopted: 1250, 900 and 800 mm. Cage No. 6 - center-to-center distance 1250 mm. Each gear cage consists of an open-type cast frame mounted on the foundation, a frame cover, middle cushions located in the side openings of the frames, end composite (three-piece) covers covering the side openings of the frames from the outside. The cover and the frame are pulled together by four studs (with nuts), which are fixed in the frame by means of a pin, and additional fixation on the studs is carried out with wedges. In the bores of the frame and the middle pillows on one side, the pillows and the cover on the other side, lower drive and upper gear rolls with chevron teeth are installed, respectively, on steel liners with Babbitt filling. The gear rollers are made of forged alloy steel. The rolls of gear stands 1400, 1250 and 900 have blades for universal spindle couplings, and the rolls of gear stand 800 have output ends with seating blades for gear spindle couplings. There are hatches in the frame and the frame cover for monitoring the condition of the gears and installing thermal alarms for monitoring the temperature of the liners. In addition, a vent is installed on the cover and holes are provided for installing a manifold for supplying lubricant to the gearing. Oil is drained through a drain hole in the lower part of the cage frame. There are also grooves to drain oil leaks. At the end of the upper gear shaft of the finishing group gear stands (on the engine side), a synchronizer is installed, which is included in the rotation control system of the working rolls of the rolling stands. The main spindle is a typical gear coupling with an intermediate shaft. In this case, the gear bushings mounted on the ends of the intermediate shaft are in engagement with the gear bushings of the engine and gear cage through the corresponding gear cages. The intermediate shaft is mounted on rolling bearings in the bores of the split housings of two bearing supports, which are fixed to the foundation. In the middle part of the intermediate shaft and on the protruding bushings of the bearing supports, seats are provided for installing, respectively, a ratchet and half-rings of a device for turning the spindles. All couplings are covered with casings. In the frame, gear rolls with chevron teeth are installed on liners with Babbitt filling, while the lower gear roll is mounted with an axial clearance of 1 ... 1.5 mm, and the upper one is self-aligned along the lower one. Gear rolls with blades for spindle couplings are forged from 4SKHNMA steel. 3. Development of the working cage design
.1 Rolls
The rolls of rolling mills perform the main rolling operation - plastic deformation (compression) of the metal. During the process of metal deformation, rotating rollers perceive the pressure that occurs when the metal is compressed and transfer this pressure to the bearings. The roll consists of several elements: a barrel, which during rolling is in direct contact with the rolled metal; journals located on both sides of the barrel and supported by bearings; end parts. The main dimensions of the rolls - their diameters and the length of the barrel - are selected on the basis of practical data (depending on the type and purpose of the rolling mill) and are specified by appropriate theoretical analysis, taking into account the bending strength of the rolls and the permissible deflection during rolling. Rolls with cushions are a unit consisting of two working and two support rolls with cushions. The work rolls are cast iron, and the support rolls are forged from alloy steel. The surfaces of their necks and barrels have high hardness. The drive ends of the work rolls are cylindrical in shape with two flats (for the spindle coupling). The work rolls are mounted in chocks on four-row tapered roller bearings. The guaranteed stall or displacement of the axis of the work roll in the chock relative to the axis of the support roll (towards the exit from the stand) is 10 mm. The work roll cushions are made of cast steel. The lower working cushions have two horn-shaped bosses. The side surfaces of these cushions and the inner surfaces of the bosses are lined with guides, hardened steel strips. The lower work cushion on the transfer side has short projections, which are used to axially fix the set of work rolls relative to the stand frame. Hydraulic plunger cylinders for balancing the upper work roll are mounted in the bores of the lower work cushions. The lower working cushions are installed with a guaranteed gap in the vertical guide openings of the frames, and the upper working cushions are installed in the guide bosses of the lower cushions. The side surfaces of the upper working cushions are also lined with hardened steel guide strips. In the axial direction, the upper working cushion on the transfer side is centered in the lower one due to the fact that the side projections of the upper cushion are installed with a gap of 1 mm in the corresponding grooves of the lower cushion. The support roller pads are made of cast steel, their side surfaces are lined with hardened steel strips. The support roll pads are installed with a guaranteed clearance in the vertical guides of the frame projects. The support pads on the transfer side have grooves for axial fixation of a set of support rolls. The support rolls are mounted in pads on fluid friction bearings (FB). The upper support roll pads have grips for connection with the balancing mechanism of the upper support roll; the lower support pads have protrusions mating with the protrusions on the slide for transferring the support roll sets. The ends of the support rolls with PZhT thrust bearing units are protected in cushions by casings included in the PZhT delivery set. The lower support cushions, through support strips with a cylindrical surface for self-installation, rest on pressure sensors (messages) mounted on the slide. The installation of the lower work roll on the rolling level is carried out by placing spacers between the support strips of the support pads and the mesdoza and fixing them on the mesdoza. On the side surfaces of all cushions of the working and support rolls there are holes for their tilting on the corresponding stands and tilters when assembling and disassembling bearing units. Fixation of the cushions in the frame against axial displacement is carried out by hydraulic latches. To mechanize the handling of work rolls, rollers are located in the cushions of the lower work roll, and four hydraulic cylinders are installed in pairs in each of the cushions of the lower support roll, the outermost (relative to the rolling axis) plungers of which are connected to guide beams along which a set of work rolls moves when they are changed. , and the nearby plungers rest against these beams, creating additional lifting force. The upward movement of the beams is limited by stops on the frame. To grab a set of work rolls during handling, a hook is installed on the bottom cushions of the work rolls. Selection of roll material, design and size Rolls operate under conditions of continuous abrasion by the metal during rolling, experiencing high stresses under dynamic loads and sometimes at high and sharply changing temperatures. Therefore, very high demands are placed on the quality of rolls, since it determines the normal operation of the mill, its productivity and the quality of the finished product. For plate hot rolling mills, rolls made of bleached cast iron and steel grades 50X and 50XN are used. For four-roll stands of hot rolling mills, forged rolls with high surface hardness (work rolls - up to 100 Shore units, support rolls 70 - 80 Shore units) and high strength (up to 800 - 900 MPa) are used; rolls with a diameter of up to 300 mm are made from alloyed chromium and chrome vanadium steel 9Х and 9ХФ, and with a diameter of more than 300 mm - from steel with a high chromium content (9Х2), chrome-molybdenum (9Х2МФ, 65ХНМ, 75ХМ) and chrome-tungsten (9Х2В). The rolls are subjected to heat treatment (hardening, tempering) according to special modes (depending on the steel grade and the size of the rolls). It is advisable to manufacture large support rolls in composite banded ones. The axle material is steel grades 55Х, 60ХР, 45ХНМ, which has good bending resistance; bandage material - steel grade 9X2. Hot rolling mill 2000. Cage No. 6 - cast iron is used on the work rolls, steel is used on the support rolls: 9ХФ, 75ХМ, 75ХМФ. The main dimensions of the rolls - their diameter and barrel length - are selected on the basis of practical data (depending on the type and purpose of the rolling mill) and are specified by appropriate theoretical analysis, taking into account the bending strength of the rolls and the permissible deflection during rolling. Determination of forces acting on the roll during rolling During rolling, the metal pressure from the work rolls is transferred to the support rolls and is absorbed by their bearings (Figure 3). Due to the greater rigidity of the support rolls, their deflection will be insignificant and the strip profile will have a rectangular cross-section. The amount of absolute compression is limited by the maximum grip angle and is determined by: ∆hmax = 0.9 * Kp * f 2 * Rp, where n - roll regrinding coefficient; - friction coefficient; - roll barrel radius. For hot rolling mills 0.9 * Kp * f 2 = 0.09 Let us determine the diameter of the work roll: = 1180 mm = 1080 mm, the length of the roll barrel is 2000 The diameter of the support roll = 1600 mmOPn = 1460 mm, the length of the barrel is 1820 mm. Figure 3 - Force action of the strip on the roll Ground reaction force P is the force with which the strip acts on the roll (rolling force) M - torque For proper operation of the mill and to avoid breakage of the rolls, frame, spindles and other parts, it is necessary to measure the total metal pressure on the rolls P (rolling force) during the rolling process. Let us determine the force acting on the rolls during hot strip rolling (Figure 4) in finishing stand No. 6 of mill 2000 at a rolling speed of 3.5 m/s. Figure 4 - Scheme for calculating the strength of the rolls of a four-roll stand mill worker cage line Roll thickness up to stand No. 6 - h0 = 42 mm; Roll thickness after stand No. 6 - h1=28 mm; Absolute compression: D h=h0-h1=42-28=14 mm. Relative compression: e =100*D h/h0=100*14/42=33.3%. Pickup arc length: °/mm. Contact friction coefficient: m=0.06. Coefficient characterizing the presence of slip zones: Yп=1/(2×m)×ln(1/(2×m)) = 1/(2×0.06)×ln(1/(2×0.06)) = 17.67. Grip Angle: a=Dh/ld=14/90.88 =0.15 We check the presence of a sticking zone on the gripping arc: d/hcp=90.88/((42+28)/2)=90.88/35=2.59 59 < 35,34
Consequently, along the entire length of the deformation zone there is only a sliding zone Let us determine the average metal pressure on the rolls and the total rolling force: For two-dimensional deformation, when broadening can be neglected, the Lode coefficient nγ = 1.15. nσ = n in*n σ* n σ * n σ
When rolling wide strips, the average is normal contact stress does not depend on the bandwidth and the coefficient taking into account the influence of the bandwidth is nв = 1. The coefficient taking into account the influence of external friction on the value of the average normal contact stress can be determined by the formula: n σ = 1+ l d/(6* hcp) = 1 + 90.88/(6*35) = 1.43 Since (lд/hcp) = 2.59 > 1 with satisfactory accuracy, the coefficient takes into account the influence of external deformation zones n σ can be taken equal to one. Since rolling is carried out without tension, the coefficient taking into account the influence of tension n σ = 1. Then the stress coefficient nσ = n in*n σ* n σ * n σ = 1 * 1.43 * 1 * 1 = 1.43 To determine the actual resistance to deformation, we use the method of thermomechanical coefficients developed by V.I. Zyuzin. σ f = σ0 * Kt * K ε * KU For St.3, the basic value of deformation resistance is σ0 = 86 MPa. At rolling temperature 1120 º C temperature coefficient Kt = 0.65. For relative compression ε=33.3% power coefficient K ε = 1.3 To assign the speed coefficient KU, we determine the average strain rate Uav = (v/ ld)*( Δh/ h0) = (3.5/0.09)*(0.014/0.042) = 12.96 s-1 According to the graph in Figure II.15, we find KU = 1.2. Then the actual resistance to deformation is: σ f = σ0 * Kt * K ε * КU = 86*0.65*1.3*1.2 = 87.2 MPa Average normal contact stress: 1.15*1.43*87.2 = 143.4 MPa Since the rolling is flat, the broadening can be neglected; the contact area of the strip with the roll is: B * ld = 1.85 * 0.09 = 0.16 m2 We find the rolling force using the formula: P = rsr * F = 143.4 * 106 * 0.16 = 22.08 * 106 N = 22.08 MN The forces between the working and support rolls are distributed as follows: Thus, the work rolls perceive only 5.11/22.08*100=23.14% of the total pressure on the rolls during rolling. Calculation of roll strength Calculation of rolls for strength comes down to determining the maximum stresses in the barrel, necks and drive end of the roll, comparing these stresses with the permissible ones. We determine the torque required to drive one roll. To do this, it is necessary to know the rolling moment and the friction moment in the roll bearings. Rolling moment Mpr = 2P ψl d = 2 * 22.08 * 106 * 0.5 * 0.09 = 1.98 * 106 Nm = 1.98 MNm Where ψ = 0.5 - resultant arm coefficient [4 p.65] during hot rolling of simple profiles. Friction moment in roll bearings Mtr = Рfd/2 = 22.08*106*0.006*0.54/2 = 36 * 103 Nm where f = 0.006 - friction coefficient of tapered roller bearings Then the torque applied to the drive end of the roll is determined by the formula: Mkr = (Mpr/2) + Mtr = (2800*103/2)+36*103 = 1.43 *106 = 1.43 MNm Maximum torque per roll 3.4 MN m. The bending moment of the roll barrel is determined by: where - a is the distance between the centers of the roll necks, m. Neck bending moment: Moment of resistance of the roll barrel during bending: Stresses arising in the roll barrel: σb.b. = 16.2< [σ] = 120 МПа, следовательно, бочка валка выдержит нагрузку. Moment of resistance of the roll neck during bending: Stress from the bending moment arising in the neck: Tangential stresses in the roll neck due to torque: For steel rolls: σeq = 93.77< [σ] = 120 МПа This means the neck will withstand the applied load. A strip 42 mm thick, b = 1850 mm, is used as blanks. The magnitude of the relative deformation will be: Deformation zone length: In four-roll stands, the condition of “natural” gripping of metal by rolls is not limiting, since practically during rolling, the gripping angle is always significantly less than the friction coefficient and depends on the elastic contact flattening of the work rolls: where (Ksr - σ av) = 500 MPa, MPa - for steel rolls Maximum contact stress σк in the middle of the contact line of two rolls loaded with force Р=q·r mm - the amount of roll flattening. Let us determine the stress in the support roll Mop = P/4*(a-b/2) σ = Miz/(0.1*d3) = 8.59/(0.1*1.63) = 20.97 MPa - in the middle of the roll barrel. The stresses occurring in the barrel and necks are less than permissible. σop = 20.97< [σ] = 120 МПа, следовательно выдержат прикладываемые нагрузки. Calculation of elastic deformation of rolls and determination of the rigidity of the roll system. The greatest deflection of the rolls occurs under the pressure of bending moments. Since the diameter of the rolls is relatively large compared to the length of the barrel, it is necessary to take into account the deflection that occurs under the action of shearing forces, causing uneven shear stresses in the cross sections and their relative shift. Thus, the total deflection of the roll in any section at a distance X from the support will be: F 1 + f2, where; 1 - deflection as a result of bending moments. 2 - deflection due to the action of transverse forces. E - elastic modulus = 2.15×105 MPa; f1 = 22.08×106 / (18.8×2.15×105 ×1.184)* = 0.0000442 m = 0.0442 mm, Roll deflection due to shear forces f2 = P / A×D²×G, Where G = 0.82×105 MPa =22.08/3.05×1.182×0.82×105 = 0.000079 m = 0.079mm the total deflection of the roll will be: f = 0.079+0.0442 = 0.123 mm. The elastic deformation of the work rolls with the strip can be neglected. The total deflection of the roll system will be equal to the sum of the deflections of the two rolls ∑f = 2f = 2*0.123 = 0.246. Then the rigidity of the roller system will be determined St = P /∑ f = 22.08×106 / 0.246 = 89756 KN/mm = 8.97 MN/mm. 3.2 Type, design and main parameters of rolling roll bearings
Roll support bearings of rolling mills transfer forces arising from metal deformation from the rolls to the frame and other components of the working stand and hold the rolls in a given position. A feature of the operation of these bearings is a high specific load (several times higher than the load of general-purpose bearings), which is due to the relatively small dimensions of the roll neck and high rolling forces. There are special requirements for the choice of bearing material for rolling rolls and their design. Currently, three types of bearings are practically used for rolling rolls: plain bearings with non-metallic liners; fluid friction bearings (FBB); rolling bearings. Rolling bearings are widely used for the rolls of four roll stands of hot rolling mills. For the rolls of these mills, roller bearings with tapered rollers (double-row, four-row) are used, since they self-align well and are able to withstand large axial loads. Rolling bearings for work rolls are selected based on their durability (for example, 10 thousand hours of continuous operation), taking into account that the bearing is subject to an axial force from the roll, which does not exceed 2% of the radial force on the rolls P when rolling strip (Q ≤ 0 ,02Р). We select the bearing according to the diameter of the roll barrel, based on the structural dimensions of the roll. Calculation of a sliding bearing. Rolling force P = 22.08 kN, roll neck diameter 920 mm, neck length 515 mm. During rolling, the upper and lower liners experience the greatest pressure, so we select them with a wrap angle. For a given neck diameter, we select liners with nominal values and lengths. The width of the liner is determined by the formula: Determine the specific pressure on the liner: Thus, the performance of the bearing is ensured. Bearings from SKF (England) have a long service life and durability. Bearings are lubricated by an automatic centralized grease lubrication system. The advantage of thick lubricants is that they do not require complex seals and act as seals themselves, protecting the rubbing surfaces from dust. They use a special thick lubricant IP - 1, periodically supplied by automatic centralized stations. In order to increase the load capacity and improve heat dissipation, it is necessary to supply liquid lubricant (grade P - 28) to the rolling bearings. Oil mist lubrication is very rational: in this case, air-atomized oil is supplied by special nozzles mounted in the bearing housing. PZhT liquid friction bearings are used as support roll bearings in four-roll stands, which have a number of advantages: Reliability under heavy operating conditions of rolling mills. Smaller in size than rolling bearings and able to withstand heavy loads. Easy to change bearings. Great durability. The diameters of the journals of the support rolls are determined by the standard sizes of the bearing, which is usually chosen as the maximum size for a given diameter of the support roll barrel, taking into account the required amount of roll regrinding. 3.3 Mechanisms for installing and balancing rolls
In order for the rolling process to proceed normally, the rolls must occupy a certain position in the working stand. For this purpose, each working stand is equipped with mechanisms and devices for vertical installation of rolls (pressure mechanisms), axial installation of rolls and balancing of the upper roll. The electromechanical type push mechanism is designed to install the rolls on a given inter-roll gap during pauses between rolling. The installed drive power, strength and kinematic design features of the pressing mechanism also make it possible to correct the metal thickness during rolling. However, due to the equipping of all finishing stands with hydraulic pressure devices (HPU) from Davy McKee, the latter are connected to the automatic thickness control system (SART) and are involved in adjusting the reduction during the rolling process in order to obtain the specified strip thickness, the required longitudinal and transverse thickness variations, and an electromechanical pressure mechanism is used in this case to roughly adjust the roll spacing. In case of emergency failures of the HPU, the strip thickness will be adjusted during the rolling process by pressing mechanisms. The hydraulic-type balancing mechanism of the upper support roll is designed to select the gaps between the bearing supports of the upper support rolls and the pressure screws between the pressure screws and nuts, as well as to move the upper support roll with the pillows when installing the solution between the rolls when installing in the transfer position. Balancing of the upper support roll is carried out by a hydraulic cylinder installed in the bore of the upper traverse of the bed assembly. The hydraulic cylinder plunger is connected by an axis to the upper rocker arm, which in turn is connected by means of rods to two side rocker arms, the arms of which extend into the frame window and are connected to the “L”-shaped lugs of the upper cushions. Choice of type and design. Structurally, the balancing mechanism is shown in the attached drawing (Fig. 6). The mass of balanced parts is 92000 kg. The mass of moving parts of the mechanism is 14000 kg. The working time in the hydraulic cylinder is 10 MPa. The rebalancing coefficient is 1.42. hydraulic cylinder plunger diameter 450 mm. The speed of movement of the pressure screw is 1.03 mm/sec. Screw thread type Pack S 600 x 24 mm. Figure 6 - Balancing mechanism for the upper support roller The greatest upward movement of the pressure screws with new rolls is 150 mm. Electric motor for driving the pressing mechanism P2 - 450 - 135 - TU4, power 400 kW, rotation speed 500 rpm. The total gear ratio from the electric motor to the pressure screw is 195.3. The diameter of the pressure nut and its height are determined based on the recommendations: D = (1.5…..1.8)d0 H = (0.95….1.10)D, where d0 is the outer diameter of the screw, mm. The diameter and height of the nut at d 0 = 600 is D = 1.66×600 = 1000 mm. H = 0.95 ×1000 =950 mm. Calculation of the pressing mechanism. The torque required to rotate the pressure screw: µ - friction coefficient at the heel = 0.1 - heel diameter = 510mmcp - average diameter of the pressure screw = 575 mm = 600×24 - outer diameter α - screw thread helix angle α = arctq 12/600 = 1º09´ at 24 mm pitch φ - friction angle = 5º40´ Mv=22.08/2* = 11040*(0.017+0.2875*0.11925) = 566.18 kNm. The reduced diameter of the shank is 615 mm, then the moment of resistance W = πd³/16 = (3.14 ×0.615³)/ 16 = 0.0457 m ³.
τ = Mv /W = 566.18×10³ / 0.0457 = 12.38×106 Pa. [τ] = 0.5[σ] = 0.5 ×120 = 60, hence the shank will withstand the torque applied to it. Normal stresses acting on the part of the pressure screw protruding from the nut σ = Q/F in, where = P/2 + (n - 1)*T - force acting on the pressure screw = 1.36 T = 86.4= 22.08*106 / 2 + ( 1.36 - 1)* 86.4*104 = 11.04×106 + 0.36 × 86.4×104 = 11.35×106 N.v = πd V ² /4 = 3.14*0.51² / 4 = 0.204 m ²
σ = 11.35*106 / 0.204 = 55.65*106 Pa. Heel friction moment: MP = Q*µп * dп /3 =11.35*106 *0.1*0.51/3 = 189.17 * 10³ Nm = πd³ /16 = 3.14*0.51³ /16 = 0.026 m ³.
Shear stresses acting on the part of the pressure screw protruding from the nut τ = 189.17*10³ / 0.026 = 7.28*106 Pa. Then the equivalent stresses will be: σ eq = 57.52< [σ] = 140 МПа, следовательно часть винта, выступающая из гайки, выдержит прилагаемые к ней нагрузки.
3.4 Bed Selecting the type and size of the bed. The frames are the basic unit of the cage and consist of two cast frames of a closed type, connected to each other by means of one upper and two lower beams. The frames are supported through slabs on the foundation. On the lower crossbars of the frames and on two traverses connecting the crossbars, hardened steel strips are installed, located in the same plane, which serve as supports and guides under the slide. The openings (windows) of the frames are lined with hardened steel guide strips. To ensure free entry of the chocks during transshipment, the width of the frame opening on the transshipment side, as well as the width of the support and lower working chocks installed in them, is 10 mm greater than on the drive side. The bores of the upper crossbars of the frames contain nuts for the pressure mechanism. Four hydraulic latches are installed on the frame racks on the transfer side to secure the work roll chocks. On the upper part of the frames, support brackets are mounted for the beams of the push mechanism drive. Four stops are installed in the openings of the frame between the guide bars, limiting the upward movement of the guide beams of the lower work rolls. The racks also have support places for installing beams between the cages. Calculation of the strength of the frame. Strength condition σ ≤ [σ], Where σ - calculated voltage value in the dangerous section of the main frame contour. [σ] = σ v/k - permissible stress value determined by the material of the frame. σ - temporary tensile strength. k - static safety factor. Frame material cast steel - 30 L - I, Cc is the rigidity coefficient of the frame. [σ] = 50 - 60 MPa. Cc = Y/δ MN/mm where, is the force acting on the frame. δ - movement caused by elastic deformation of the frame. For hot rolling mills: Сc = 10-15 MN/mm. The maximum vertical force acting on the frame from the side of the roll neck and transmitted to it through the pressure screw Y = P /2. Horizontal forces are not taken into account due to their insignificance. δ = Y / Cc mm. The total vertical movement of the frame in the direction of action of forces Y should not exceed 0.6-1.0 mm for hot rolling mills at Y = 5-15 MN. Ss = tg α = ∆Y/∆S , because tg α = const, it follows that the rigidity of the frame does not depend on the value of the force Y and is determined only structurally. Rolling force P = 22.08 MN (calculated in paragraph 3.1.2). Sectional area of the upper cross member: Н1*В1-(d2*h2+h1*d1) = 1.45*1.8-(0.6*0.5 + 0.95*1.0) = 2.61 - 1.25 = 1, 36 m ².
Statistical moment of cross-sectional area relative to the X axis: x = B1*H12/2 - d2*h2*(h1+(h2/2)) - (d1*h12)/2 = 1.8× 1.452/2 - 0.6*0.5*(0.95+(0.5/2))-(1.0*0.95²)/2 = 1.892- 0.36 - 0, 45 = 1,082 m ³.
Coordinates of the center of gravity of the cross-sectional area along the Y axis: Ус = Sk / F1 = 1.082 m ³/1.36 m ² = 0.79 m. Figure 7 - Main dimensions of the four-roll stand frame of the 2000 mill Neutral axis position: y1 = yc = 0.79 m; у2 =Н1 - ус = 1.45 - 0.79 = 0.66 m Moment of inertia of the cross-sectional area of the upper cross member relative to the central axis passing through the center of gravity of the section: Xc = J1 = (B1*H13)/12 - [(d2*h2 ³)/12 + d2*h2*(h1+h2/2 - mustache) ²] - [(d1*h1³)/12+d1*h1*( us -h1/2) ²]= =1.8*1.45³/12--= 0.4573 - - = 0.4573 - 0.056 - 0.164 = 0.237 m4. Cross-sectional area of the rack: B2 * H2 = 0.8 ×0.8 = 0.64 m ².
Moment of inertia of the cross-sectional area of the strut: B2 * H2 ³/12 = 0.8 * 0.8³/12 = 4.4096 /12 = 0.034 m4. Cross-sectional area of the lower cross member: H3 * B3 = 1.44 * 0.8 = 1.15 m ².
Moment of inertia of the cross-sectional area of the lower cross member: B3 * H3 ³/12 = 0.8×1.44³/12 = 0.199 m4. The dimensions of the main frame contour will be as follows: B + Н2 = 1800 +800 = 2600 mm = h + уc + (Н3/2) = 7360 + 790 +1440/2 = 8870 mm. (see figure 7) Force acting on the frame: U = P / 2 = 22.08 /2 = 11.04 MN E = 2 * 105 MPa = 0.75 * 105 MPa Check calculation of the frame. ) we check the strength of the frame in cross-section I-I top cross members. Moments of resistance of the cross section to bending: JХс/у1 = 0.237/ 0.79 = 0.3 m ³
W2 = JХс /у2 = 0.237 /0.66 =0.359m ³.
The bending moment in the middle of the upper cross member is determined by the formula: The highest compressive stress along the internal contour of the frame: σ1 =MP/W1 = 7*106/0.3 = 23.3*106 Pa σ1 ≈ 23 MPa< [σ] = 60 mPa, thus the strength condition is satisfied. ) The strength of the rack is checked in section II-II: B2 * H2 ²/6 = 0.8*0.8² / 6 = 0.0853 m ³.
Bending moment in the stand: The highest voltage in the rack along the internal circuit is determined by the formula: σ1 = Y/2F2 + Mst /W ≤ [σ] σ1 = 11.04*106/2*0.64 + 0.157*106 /0.0853 = 8.63*106+1.84*106 = 10.46*106 Pa σ1 = 10.46 MPa< [σ] = 60 МПа - условие прочности стойки выполняется.
) the strength of the lower cross member is checked in section III-III Moment of resistance of the cross section to bending: B3*H3² /6 = 0.8 * 1.44² /6 = 0.27 m³. Tensile (compressive) stress is determined by the formula: σ = MP/W = 7 * 106/0.27 = 25.93 * 106 Pa σ = 26 MPa< [σ] = 60 MPa - the strength condition of the lower cross member is met. Check calculation of frame rigidity. Since J1/J3 ≠ 1, the movement of the frames in the direction of force Y is determined: δ 1 = 1 / 2 E [Mst × (l2 l1 / J2 + (l12 (J1 + J3)/12J1J3 ) * 2(Mst - Mp))] δ1 = 1/(2*2*105)* = 25*10-5* = 25*10-5*(117.19*106-37.63*106) = 0.2 mm. Movement of the frame due to the action of transverse forces due to deformation of two crossbars: Movement of the frame from the action of longitudinal forces due to deformation of two posts: Full bed movement: δ = δ1 + δ2 + δ3 = 0.2 +0.18+ 0.38 = 0.76 mm. Bed rigidity C = Y / δ = 11.04*106 /0.76 = 14.53 MN/mm. This rigidity is considered satisfactory for hot rolling mills. 3.5 Calculation of the stiffness coefficient of the working stand
Stiffness is understood as the magnitude of the rolling force per unit deformation of the stand. The rigidity of the working cage is determined by the formula: /Skl = 1 /Sv +1 /Sst +1 / Spv +1/Spod + 1/Snu + 1 /Sdr el where: Skl - cage rigidity, St - rigidity of the roller system, Spv - rigidity of roller bearings, Spod - the hardness of the pillows, Snu - the rigidity of the pressure device, S dr el - the rigidity of other cage elements. Since the rigidity of the roller system and the rigidity of the frames have the greatest influence on the rigidity of the stand, the rigidity of the stand can be represented as follows: 3.6 Fastening the cage to the foundation
When concreting the foundation for cage No. 6, anchor reinforcement was laid - cast anchor slabs 100×500, into which the foundation bolts are screwed. Foundation bolts consist of a stud, nut, and washer. The studs are laid and screwed into the anchor plate after the foundation is made. The diameter of the bolts connecting the frame to the slab is made: d "0.1D + 5 ÷ 10 mm;" 0.1×1460 + 5" 151 mm. The height of the slab is approximately: 3.7 Type and design of roll reinforcement
The conductive fittings are designed to hold the strip along the rolling axis when it is inserted into rolls and directly into the rolling process. Wiring is installed on the front and rear sides of the stands to center the strip relative to the rolling axis, as well as to prevent the rolls from binding. To facilitate the entry of the strip into the rolls, guide rulers are placed on the front side of the stands. Control of the rulers and adjustment of the wiring should be as simplified and mechanized as possible, which will ensure minimal loss of time when rebuilding the mill and changing rolls. Figure 8 - General view of the wiring between the stands of the roughing group Figure 8 shows a general view of the rulers and wiring between the cages. Cast rulers 1 are placed in front of the stand on guide bars 2. Along these bars, the rulers move with screws perpendicular to the rolling axis. On the rear side of the cage there are feet 4, to which the lower wires 5 are attached. The upper wires 6 are suspended on counterweights to the wire beam 7. When transferring work rolls, the guide rulers and the rear table must be moved away from the stands. To move the rear table of the previous stand and the guide bars of the next stand, an electric motor is installed that turns shaft 8 through a gearbox, on which sits a lever 9 connected to rods 10. When the shaft 8 is turned, the guide bars and table move along the bars 11 and move away from the stand. For more convenient operation, it is better to attach the upper wiring to the levers, and not hang it on chains, as on some mills. The design of the upper wires and their contact with the work roll must ensure the removal of cooling water without getting on the surface of the strips being rolled. The strip coming out of the previous stand is directed to the rolls of the next stand, while the electromagnetic controllers automatically turn on the electric motor, turning the shaft and the lever with the idle roller 12 at the end, the latter will tend to take the upper position, due to which the strip will be under some ( slight) tension. In order to prevent the formation of a large strip loop, a synchronous regulator is installed at one end of the shaft, which, when the angle of rotation of the lever with roller 12 increases, gives an impulse (command) to decrease (increase) the rotation speed of the main electric motor of the roll drive of the previous (subsequent) stand. 4. Type and design of transmission mechanisms of the main line of the working stand
The transmission mechanism in stand No. 6 is a gearless drive through the main spindle, gear cage and spindles. With a gearless drive, the electric motor is connected directly to the gear cage by the main spindle. Gear stands serve to transmit torque from the engine to the spindles and work rolls. Each gear cage consists of an open-type cast frame mounted on the base of the frame cover, middle cushions located in the side openings of the frame and end components (of three parts) covers covering the side openings of the frames from the outside. The main spindle is a typical gear coupling with an intermediate shaft. In this case, gear bushings are mounted in engagement with gear bushings of the engine and gear cage through corresponding gear cages. The intermediate shaft is mounted on rolling bearings in the bores of split housings of two bearing supports, which are fixed to the foundation in the middle part of the intermediate shaft and on nearby supports there are seats for installing, respectively, a ratchet and half-rings of a device for turning the spindles. All couplings are covered with casings. In the frame, gear rolls with chevron teeth are installed on liners with Babbitt filling, while the lower gear roll is mounted with an axial clearance of 1…..1.5 mm, and the upper one is self-aligned along the lower one. Gear rolls with cavities for couplings and spindles are forged from steel 40ХНМА. There are hatches in the frame and the frame cover for monitoring the condition of the gears and installing thermal alarms for monitoring the temperature of the liners. The cover has holes for installing a lubricant supply manifold to the gearing. Oil is drained through a hole at the bottom of the cage body. The transmission of torque from the gear cage directly to the work rolls of the cage is carried out by a universal spindle device. The spindle device of the 6th stand as well as the axial shift system are supplied by Davy McKee. 5. Selecting the type and determining the power of the main engine
The torque created by the engine when the rolls rotate is determined by the formula: Mdv = Mpr / i+ Mtr + Mxx + Mdin where: Mtr is the moment of additional friction forces given in the engine: Mхх - idle moment: Mdin - dynamic torque in view of the engine: - gear ratio between the engine and the rolls (ish.k. = 1; gearless drive). When rolling metal on a four-roll mill, the pressure of the metal on the work roll is transferred to the non-driven support rolls, so friction losses occur only in the bearings of the support rolls. Mtr = Рdn * f / i + ( 1/η lane - 1) * ((Mpr + Рdn *f) / i); Where η lane = η spin* η sh.k. * η couplings - overall efficiency of transmission mechanisms η = 0.97* 0.9³ * 0.97 = 0.88 the friction moment will be: Mtr = (22.08*106 *1.18 * 0.006/1 + (1/0.88 - 1) * ((1.98*106 + 22.08*106 * 1.18*0.006)/1 = 180174.67 Nm = 180.17 kNm The idle torque is determined by the formula: Мхх = ∑((Gn*fn*dn)/2in), where: Gn is the weight of the part, fn, dn are the friction coefficient and the diameter of the journals of the rotating part, in is the gear ratio from the engine to this part. We take the idle torque equal to 5% of the rolling torque applied to the engine shaft: Mxx = 0.05* Mpr /i = 0.05* (1.98*106)/1 = 0.099*106 MN. Engine Torque: Mdv = 1.98*106/1 + 180174 + 99000 = 2259174 Nm. The angular speed of rotation of the shaft is determined by the formula: ω dv = 2 π* p/60, where: n - engine rotation speed n = 50 rpm ω dv = 2 * 3.14 * 50 / 60 = 4.4 s-1. Then the required power to rotate the rolls is: dv = mdv * ω dv. N doors = 2259174 * 4.4 = 9.94 * 106 W. We accept for installation a 12 MW motor of type 2MP14200 - 50 UZ. 6. Type and design of devices for transferring rolls
The roll change mechanism is designed for simultaneous replacement of work rolls on all or several stands of the finishing group, as well as for dumping and filling of support rolls. The roll change mechanism is installed on the service side of the finishing stands below floor level. The roll changing mechanism consists of seven (according to the number of stands) independent mechanisms for changing working and support rolls, interconnected by a train of trolleys designed for lateral shifting of working rolls along the front of the stands. Each of the installation change mechanisms is opposite the window of the corresponding cage and consists of a frame assembly, a trolley frame, and an upper frame of two trolleys Longitudinal and one transverse movement trolley, hydraulic drive beams, slab flooring. The frame assembly consists of a welded frame itself with guides for moving the cage slide, installed on the foundation and rests on the frame tooth. Beams with “C”-shaped guides are fixed to the frame, and rails are in turn installed on the beams. The second end of the beams outermost from the cage simultaneously rests on the frame of the upper transverse frame lifting mechanism fixed to the foundation. On the frames installed on the foundation, the mechanisms for lifting the hook (latch) and the power hydraulic cylinder for dumping and filling the working and support rolls are mounted. The hook lifting mechanism consists of levers pivotally mounted on the frame (from the cage side) and driven by a hydraulic cylinder, carrying a ruler. In the “C”-shaped guide beams on the rollers there is a bogie frame, which has a hook for engaging the tooth of the cage slide. A lever with a roller is rigidly fixed on the same axis with the hook, and the roller, when running over the raised ruler, has the ability to rotate the lever and raise the hook. The trolley frame is pivotally connected to a power hydraulic cylinder through a plug-in axle and has a vertical column with guides. An upper frame is installed on the bogie frame, the guides of which cover the directions of the bogie frame column. The upper frame has a cantilever part, at the end of which there is a folding hook for engagement with a tooth on the lower working cushion or with an insert tooth. On the side opposite to the cantilever, a counterweight is installed on the upper frame. Through the side rollers, the upper frame in its initial position rests on the sliders of the upper frame lifting mechanism, which in turn are installed in the corresponding frame guides of the lifting mechanism and are driven through levers from one hydraulic cylinder. The cantilever part of the upper frame in the lower initial position rests through rollers on a transverse movement platform (trolley), which is mounted on rail guide beams by means of rollers. The platform is equipped with rail-type guides on which one of the longitudinal movement trolleys is installed along the axis of the cage through rollers. The second trolley is installed on guide beams located on the foundation in the spaces between the transfer openings of the cages. The platform in the lower front part has brackets that are connected by their grips to the tooth of the cage slide. Each of the carts is equipped with guides for moving the lower work roll cushion rollers or insert rollers. The carts are connected to each other in a train through grippers in such a way that the guaranteed gap between the grips of the carts located in the gaps of the stands and the cart installed along the axis of the cage ensures unimpeded removal of the latter (together with the platform) from the cage when transferring support rolls. In this case, one of the grips of each mating pair is rigidly mounted on the trolley, and the other has the ability to be installed relative to the first with subsequent fastening with bolts. In addition, the mechanisms for changing the outer stands No. 7 and No. 13 (14) are equipped with hydraulic cylinders for moving the train of carts and removable flooring covering the hydraulic cylinders. In this case, the outer carts have end rollers, which are installed with a gap under the decking, and the hydraulic cylinders, supported through separate frames on the foundation, are pivotally connected to the carts by means of eyes with stone. The trolleys installed on the beams in the inter-handling spaces are equipped with brackets with side clamps in the form of a spring-loaded ball, centered in the groove of a special beam follower, which prevents the displacement of these trolleys when the platform is retracted. The openings between the cage and the platform of each changing mechanism are covered with a removable floor plate, which on one side rests on the frame tooth, and on the other on the platform brackets and is centered, respectively, between the welded stops of the frame and the ledges of the foundation facing slabs. There are guides on the floor plate, which are connected with a gap on one side to the guides of the cage beams, and on the other side to the guides of the trolley; in this case, the guides of the beams, floor slab and trolley lie in the same plane. In turn, at that level, adjacent to the guides of each cart installed along the axis of the cage are the guides of the upper frame (in the initial position), and to them are rail guides along which the work rolls are transported to the roll grinding workshop by means of special self-propelled carts. When changing support rolls, a special insert with rollers is used, which is installed by crane on the guides of the trolley located along the axis of the cage. The insert is pushed into the cage and removed from the cage by moving it from the hydraulic cylinder of the upper frame. To do this, the insert has a tooth that engages with the hook of the upper frame. The extreme positions of the trolley frame of the upper frame lifting mechanism, the hook lifting mechanism of the hydraulic drive for moving the train of trolleys (as well as the extreme positions of the latches for axial fixation of the stand roll pads) are controlled by limit switches. Changing work rolls. Before transferring rolls, the trolley train must be in its original position. In this case, the positions of the trolley are located along the axes of the stands, and the trolleys, with a pre-installed set of new rolls, are located on the side of the stand. The mill is stopped for transshipment after the strip leaves the last stand. The stands are stopped by electrically braking the engine based on a signal from the angular position sensor; the inter-stand fittings are moved outside the windows of the stand frames; the latches of the work rolls are disconnected, the pressure screws, together with the upper support roll, are raised to the upper position; the hydraulic pipelines to the work rolls are disconnected. Beams of the lower support rolls, which serve as guides for moving the work rolls and are installed at the transfer level. Next, the upper frame of each shift mechanism rises to the upper position and moves from the power hydraulic cylinder along with the trolley frame to the working cage. After the hooks of the upper frame are engaged with the teeth of the lower cushion by the reverse stroke of the hydraulic cylinder, a set of worn work rolls is removed from the cage and installed on the carts. The hooks are disconnected from the cushion of each set of work rolls and hydraulic cylinders move the train of longitudinal movement carts to shift the worn sets of work rolls to the side while simultaneously installing new sets along the axis of the stands. By means of hooks, the upper frames are connected to new sets of work rolls and from hydraulic cylinders (when moving the frames of the trolleys to the cages), they are loaded into the cage. After filling is completed, the upper frame is retracted (together with the trolley frame) to its extreme position and lowered to the original level, the inter-roll reinforcement is installed in the working position, the stands are prepared for work and adjusted. In addition to synchronous change of work rolls simultaneously on all stands, it is possible to change rolls simultaneously on all stands; it is also possible to change rolls on a separate stand. After transshipment, sets of worn work rolls are installed along the stands, coupled to self-propelled carts and transported to the roll grinding workshop. Changing support rollers. The transfer of support rolls of finishing stands is carried out after removing a set of work rolls from the stand. The hoses for supplying lubricant and hydraulics to the support pads are disconnected, the latches securing the cushions are removed, and the floor plates are removed. The insert is inserted into the cage using the upper frame. At the same time, the hook of the trolley frame, when the ruler of the hook lifting mechanism is lowered, automatically engages with the tooth of the cage slide. Next, the upper support roller is lowered onto the spacer and the set of support rollers, together with the platform and bogie frame, is pushed out of the cage using a hydraulic cylinder. The crane is used to remove the upper support roll, insert the lower support roll, and then install a new set of rolls in the reverse order and insert it into the cage. Before retracting the hydraulic cylinder to its original position, the hook lifting mechanism is activated and raises the ruler. After turning on the hydraulic cylinder, the roller of the trolley frame lever, running over the ruler, holds the hook in the raised position and prevents its engagement with the tooth of the slide. Conclusion
Stand No. 6 is intended for compressing the rolled stock in thickness and obtaining a strip h1 = 28 mm from the rolled stock h0 = 42 mm, followed by rolling in stands 7 - 13. The presented calculation shows that all technical characteristics allow this to be done. Literature
1. Korolev A. A. “Designs and calculations of machines and mechanisms of rolling mills” - M. Metallurgy. 1985. Korolev A.A. “Rolling mills and the formation of rolling shops” - Uch. manual for universities - M. Metallurgy. 1981. Tselikov A.I., Tomlenkov A.D., Zyuzin V.I. "Rolling Theory". Directory - M. Metallurgy. 1982. Tselikov A.I., Polukhin P.I., Grebenik V.M. “Machines and units of metallurgical plants”, volume 3 - M. Metallurgy 1988. Tselikov A.I. Smirnov V.V. “Rolling mills” - M. Metallurgizdat. 1958 Korolev A.A. Mechanical equipment of rolling and pipe shops: Textbook for universities. - M.: Metallurgy, 1987 Mechanical equipment of wide-strip hot rolling mills V.G. Makogon et al. Metallurgy 1969.
One of the largest projects of Corporate Systems LLC is now at the final stage of development - a multimedia training system for training specialists at control stations PU7 and PU9 of the wide-band hot rolling mill 2000.
The continuous wide strip hot rolling mill 2000 is designed for the production of hot-rolled strips from carbon and low-alloy steel grades. Consists of:
- area for supplying slabs to furnaces and loading slabs;
- roughing group of equipment (PU7);
- sections of the intermediate roller table and flying shears (PU9);
- equipment finishing group (PU9);
- cleaning equipment group.
The project being developed by Corporate Systems LLC covers 5 jobs:
- operator of the roughing group of equipment;
- rolling machine for roughing group of equipment;
- operator of intermediate roller table and flying shears;
- finishing group operator;
- finishing group roller.
Each workplace has its own specific characteristics and is designed to perform certain tasks. For example, the main goal of the roughing group is to obtain the output parameters (width, thickness, temperature) of the strip of the required quality behind the sixth stand.
The system completely simulates all screens and control panels used by specialists, thereby allowing you to study the work, as well as the main actions performed with their help. To do this, the system is equipped with many scenarios with different types of tasks:
test questions (involve users to select one answer from several offered);
self-answer questions (requires users to enter their own answers);
questions of indicative type (involve the indication of the necessary elements on screens or control panels);
execution of an operation (implying that users perform the required operations).
The system provides two modes of passing scenarios:
demonstration (used for training and is characterized by the presence of various tips (intended for the user to reinforce theoretical material), as well as indication (highlighting elements that are necessary to complete the task));
testing mode (used directly to test the user’s knowledge).
To ensure that the training is as close as possible to the actual operation of the mill, the program provides 3D animation that allows users to see the results of all the actions they perform in the scenarios directly on the mill model: the state of the equipment (for example, control of pressure screws, encopanels, flying shears, roller table sections), operating speed, possible accidents (for example, slabs getting stuck, strip bending), etc.
The system also implements various simulation models:
model of deformation regime;
speed mode model;
temperature model;
- tension model;
loading model of main drives, etc.
They allow you to imagine the process of rolling metal as it is carried out in reality.
The most important component of the system is a three-dimensional model of the mill, which allows specialists to study in detail the design of the roughing and finishing group equipment, as well as the intermediate roller table and flying shear sections.
The design considers not only the structure of groups of equipment, but also individual elements (for example, the detailed structure of cages). Convenient navigation, detailed descriptions properties and technical characteristics elements, as well as the ability to customize the user interface, make the learning process as easy as possible.
The design is also supplemented with various video materials dedicated to the operation of the equipment (flying shears, roller table, finishing group, etc.), and animation videos demonstrating the technology in detail (the operation of loop holders, rolling technology).
In addition, the system is equipped with many reports that allow you to obtain information about the rolling performed (rolling plan).
The ability to view test results allows you not only to obtain information about the correctness of completed tasks and the time spent, but also to track the operations that the user performed while going through the scenarios.
Reproducing user actions in a recording makes it possible to subsequently visually trace the testing process.
Thus, the combined use of computer graphics, animation, “live” video and other media components will provide a unique opportunity to make the material being studied as visual as possible, and therefore understandable and memorable. This is especially true for mill 2000 specialists who must learn large number emotionally neutral information - for example, production instructions, technological maps, regulatory documents. Convenient interface and navigation, detailed user and technological instructions make working with the system as simple as possible.