CN117987622A - Method for improving temperature uniformity of high-temperature annealed steel coil of oriented silicon steel - Google Patents
Method for improving temperature uniformity of high-temperature annealed steel coil of oriented silicon steel Download PDFInfo
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- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
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Abstract
A method for improving the temperature uniformity of a high-temperature annealed steel coil of oriented silicon steel comprises the following steps: 1. after a horizontal steel coil of the oriented silicon steel high-temperature annealed steel coil is turned into a vertical steel coil, performing embedded couple temperature measurement at an embedded couple point, and then performing high-temperature annealing in an annular annealing furnace or a tunnel annealing furnace provided with an inner cover and a chassis, wherein upper and lower part burners with a single control loop perform closed-loop feedback separate control, so that the temperature of a local cold zone of the steel coil is increased; and (3) adding a heat accumulator or a heating body in the center of a furnace platform for improving the uniformity of the transverse temperature of the inner core of the steel coil, and performing closed-loop feedback control according to a temperature thermocouple. The problem of poor temperature uniformity of steel coils in the high-temperature annealing process is greatly improved by changing the temperature control mode of burners of the existing annular annealing furnace or tunnel annealing furnace and the method of adding heating bodies and the like in a 'local cold area'.
Description
Technical Field
The invention relates to a production method of oriented silicon steel, in particular to a production method of high-temperature annealing of oriented silicon steel.
Background
The oriented silicon steel is an indispensable soft magnetic material in the electric power and national defense industry, and the core technology is that fine dispersed second phase particles are utilized to inhibit the normal growth of primary recrystallized grains, and the interface energy difference of grains with different orientations is utilized to finish secondary recrystallization in the high-temperature annealing process, so that a sharp Goss texture is formed. In addition to accomplishing secondary recrystallization, metallurgical objectives of high temperature annealing include: making MgO coated on the surface of the steel plate chemically react with SiO2 in the surface oxide film to form a Mg2SiO4 bottom layer; purifying steel and removing N, S, al elements.
The production flow of the oriented silicon steel is generally as follows:
steelmaking, slab rolling, normalizing and pickling, cold rolling, decarburization annealing, nitriding, mgO coating, high-temperature annealing, stress relief annealing and insulating film coating to form decarburization annealed steel coil. The high-temperature annealing process is usually completed in a hood-type annealing furnace, an annular annealing furnace and a tunnel annealing furnace, but the hood-type annealing furnace is difficult to adapt to mass production due to low production efficiency, high energy consumption and the like; at present, the high-temperature annealing of the oriented silicon steel mostly adopts an annular annealing furnace or a tunnel annealing furnace.
Based on the arrangement of facilities within a ring annealing furnace or tunnel annealing furnace, as shown in fig. 1. Heating burners are arranged on the furnace wall, and are arranged at the upper part and the lower part of the inner side and the outer side of the furnace wall, and the heating burners directly spray mediums such as natural gas/coal gas into the furnace for burning. And each control loop corresponds to the upper part and the lower part of the inner side and the outer side of the furnace wall, wherein the horizontal height of the lower burner is close to the height of the inner chassis of the inner cover, and the horizontal height of the upper burner is higher than the top height of the inner cover. The 4 burners of the control loop perform closed-loop feedback control according to the furnace top or chassis thermocouples, and the combustion load of the corresponding 4 burners is not greatly different. However, actually, due to the difference of thermal fields of the high-temperature annealing furnace, the temperatures corresponding to different burners of the control loop are not completely the same, the temperature difference between the positions of the upper part burner and the lower part burner is relatively large, and the temperatures of the positions of the upper part burner and the lower part burner are relatively large compared with those of the inner ring burner and the outer ring burner.
The high-temperature annealing process is a process that a steel coil with an MgO coating on the surface of the steel coil is subjected to whole-coil annealing in a high-temperature annealing furnace, and the main heat conduction mode of the vertical steel coil is carried out through the upper end face and the lower end face, so that the temperature non-uniformity of different positions of the steel coil is obvious. To achieve completion of secondary recrystallization; forming a glass film bottom layer; for the metallurgical purpose of purifying steel and removing N, S, al elements, at present, an annealing process system with five stages is mainly adopted, and the annealing process system comprises the following steps: and (3) a primary heating section: the decarburized steel coil is turned over by a horizontal steel coil to be filled into a furnace, nitrogen or hydrogen-nitrogen mixed gas containing H2 in a certain proportion is used for replacing air, and when the steel coil is heated to 350-450 ℃, mg (OH) 2 in MgO starts to decompose and release chemical water; low heat preservation section: heating to 550-650 ℃ and preserving heat for a period of time, removing free water and combined water in MgO, reducing the temperature difference between cold and hot points, and slowly heating in the stage; and (3) a secondary heating section: heating at a certain heating speed to form a magnesium silicate bottom layer and developing secondary recrystallization in the heating process; high heat preservation section: after the secondary recrystallization and bottom layer formation are completed, preserving heat for about 20 hours at about 1200 ℃ and removing impurity elements to eliminate the magnetic aging problem of the product; and (3) a cooling section: the coil was cooled to about 300 c and discharged. The five phases constitute a complete annealing cycle, one cycle typically lasting 6-8 days, as shown in fig. 2.
The simulation study is conducted on the temperature state of each part of the steel coil in the heating process of the oriented silicon steel, and the result is shown in fig. 3. It can be seen that the temperature difference of cold and hot spots of each part of the steel coil in the heating process of the oriented silicon steel is up to more than 300 ℃. The uneven temperature of the steel coil in the high-temperature annealing process can lead to the following effects: a. the cold and hot spots of the steel coil are asynchronous due to secondary recrystallization, so that the magnetic property of the final strip steel is poor in transverse/longitudinal uniformity; b. the quality and the surface quality uniformity (defects such as local oxidation color, watermarks, bright spots and the like) of the bottom layer of the final strip steel are deteriorated due to the difference of water drainage and additional oxidation at different positions of the steel coil; c. the expansion and contraction of the steel coil at different positions are not synchronously increased, so that plate type defects (side waves, strip-shaped indentations, horseshoe-shaped indentations and the like) and the unreeling of the steel coil are caused, and the normal unreeling of the subsequent process is influenced.
The Chinese patent publication No. CN202786362U discloses a HITT single-coil stacking hood-type annealing furnace for heat treatment of oriented electrical steel, which comprises the following steps: the furnace comprises a furnace platform, an inner cover covered on the furnace platform, and a heating cover or a cooling cover arranged outside the inner cover; the furnace table is provided with a sealing element, the inner cover is connected with the sealing element in a sealing way through a hydraulic clamping device, and a sealed annealing space is formed between the furnace table and the inner cover; the furnace platform is provided with a blowing pipeline for blowing the atmosphere of the furnace body, the heating cover is provided with a heating system, and when the annealing furnace heats or cools the coil, the coil is stacked on the furnace platform singly. The utility model can realize less consumption of protective atmosphere, the treatment temperature can reach 1200 ℃, the time for reaching the maximum cooling temperature required by unloading can be shortened, the uniformity of annealing temperature is improved, the annealing time is shortened, the optimal heat transmission from the inner cover to the surface of the coil can be realized, the energy consumption is reduced, and the maximum flexibility and the maximum temperature uniformity of the whole coil load are ensured. The single-coil stacking hood-type annealing furnace has low production efficiency and high energy consumption, is difficult to adapt to mass production, and has limited improvement on the uniformity of the temperature of the steel coil.
The Chinese patent publication No. CN103667874A discloses a production method for shortening furnace time of oriented silicon steel during high-temperature annealing, and the internal temperature of a steel coil is homogenized by arranging two steps at the low-temperature stage of high-temperature annealing. However, the patent does not disclose parameters such as temperature rising speed, and the like, and the problem of temperature difference inside the steel coil after the low heat preservation stage cannot be solved, and the product performance is not excellent.
The Chinese patent with publication number of CN205398688U discloses a device for improving the temperature uniformity of a steel coil of a circular furnace, which comprises the following components: a top cover and a bottom plate. The top cap is fixed in the upper end of coil of strip, and the upper end of coil of strip is sealed to the top cap, and the top cap has the effect of keeping apart heat radiation. The bottom plate upper end is provided with first strengthening rib, and the bottom plate setting is in the below of top cap, and the coil of strip is placed on first strengthening rib, and the lower extreme of coil of strip is used for the heat dissipation with the clearance that constitutes of bottom plate, the upper end of the sealed coil of strip of top cap, and the top cap has the effect of keeping apart heat radiation, can reduce the cold point of coil of strip upper end, the difference in temperature value of hot spot, from this, has improved the homogeneity of coil of strip temperature. However, by adding the device on the upper end face and the lower end face of the steel coil, damage to the upper end face and the lower end face of the steel coil is easy to occur in the high-temperature annealing process, and the subsequent process is difficult to unwind. Meanwhile, the device has large cost investment and shorter service life. Meanwhile, the method has certain limitation in improving the temperature uniformity of the steel coil.
In order to characterize the temperature uniformity of the steel coil, the inventor determines a technical scheme capable of effectively characterizing the temperature uniformity of the steel coil by carrying out a series of experiments:
In the high-temperature annealing and heating process of the steel coil, the temperature difference of different positions is relatively large, the temperature rising speed is the fastest and the steel coil is counted as a hot spot at the position close to the outer ring of the upper end surface; because of the high-temperature annealing and heat insulation effects of the MgO coating, heat transfer between layers of the steel coil is blocked by MgO, and heat resistance is high, so that the main heat conduction mode of the steel coil is carried out through the upper end face and the lower end face, and the central positions of the steel coil in the middle and the lower parts of the steel coil are the slowest in heating speed and counted as cold points.
The inventor has found that the temperature distribution of the steel coil at different positions in the high-temperature annealing process is known, and the embedded even temperature measurement is carried out at the position of the steel coil which can be characterized by the cold and hot spot temperature after decarburization annealing coating, and the arrangement of the embedded even coil temperature measurement points is shown in figure 4. The buried coil is annealed at high temperature in a high-temperature annealing furnace, and the temperature change condition of the buried coil at cold and hot spots is recorded, and the result is shown in figure 5. It can be seen that the cold and hot spot temperature difference is up to 300 ℃ or more, and occurs in the first 20 hours of high temperature annealing. The temperature uniformity of the steel coil is reflected by the temperature change and the difference value of the cold and hot spots in the high-temperature annealing process.
Disclosure of Invention
In order to overcome the problems and characterize the temperature uniformity of steel coils, the invention aims to provide a method for improving the temperature uniformity of high-temperature annealed steel coils of oriented silicon steel, which greatly improves the problem of poor temperature uniformity of steel coils in the high-temperature annealing process by changing the burner temperature control mode of the existing annular annealing furnace or tunnel annealing furnace and the method for adding heating bodies or heat accumulators in a 'local cold area'.
The technical scheme of the invention is as follows:
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized by comprising the following steps of:
In the production flow of oriented silicon steel, when the steel coil enters a high-temperature annealing process after decarburization annealing, after a horizontal steel coil is turned into a steel coil, the hot spot and the cold spot of a buried even coil are buried and subjected to even temperature measurement, then high-temperature annealing is performed through an annular annealing furnace or a tunnel annealing furnace provided with an inner cover and a chassis, the upper part burner and the lower part burner with a single control loop are subjected to closed-loop feedback separation control so as to improve the temperature of a local cold area of the steel coil and increase the burning load of a lower part burner,
A heating body is arranged between the two inner covers (namely the 'shielding' part of the inner cover) so as to solve the problem that the temperature of a local area is low, namely a 'local cold area', and further improve the uniformity of the steel coil in the high-temperature annealing process.
The burner is mainly arranged on two sides of the furnace wall, a heating body is not arranged at the shielding part between the two inner covers, the temperature of a local cold area is lower, and a relatively low temperature area is formed at the shielding part between the two inner covers corresponding to the steel coil. The middle heating body is added at the 'shielding' part between the two inner covers, so that the problem of low temperature of a local area is solved, and the problem of poor uniformity in the high-temperature annealing process of the steel coil temperature is further solved;
The method for improving the temperature uniformity of the high-temperature annealed oriented silicon steel coil is characterized in that a heat accumulator or a heating body is added in the center of a furnace table or between two chassis for improving the problem of the transverse temperature uniformity of the inner core of the coil, and closed-loop feedback control is performed according to a temperature thermocouple.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that in order to improve the heating rate of the steel coil, an electric heating body and a temperature thermocouple are arranged between the lower part of a steel coil chassis and a furnace table, and each steel coil base electric heating body is provided with an independent regulator and performs closed-loop feedback control with thermocouple temperature measurement.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized by separately controlling the upper burner and the lower burner of a single control loop, wherein the upper burner performs closed-loop feedback control according to a furnace top thermocouple, and the lower burner performs closed-loop feedback control according to a chassis thermocouple.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that in order to solve the temperature distribution condition of different positions of the steel coil in the high-temperature annealing process, the embedded couple temperature measurement is carried out on the positions of the cold-spot temperatures of the steel coil after decarburization annealing coating, the positions of the embedded couple-spot temperatures are the outer rings of the near end surfaces of the upper parts of the embedded couple coils, and the positions of the embedded couple-spot temperatures are the central positions of the steel coil in the middle and lower parts of the embedded couple coils.
In the high-temperature annealing and heating process of the steel coil, the temperature difference of different positions is relatively large, the temperature rising speed is the fastest and the steel coil is counted as a hot spot at the position close to the outer ring of the upper end surface;
Because of the high-temperature annealing and heat insulation effects of the MgO coating, heat transfer between layers of the steel coil is blocked by MgO, and heat resistance is high, so that the main heat conduction mode of the steel coil is carried out through the upper end face and the lower end face, and the central positions of the steel coil in the middle and the lower parts of the steel coil are the slowest in heating speed and counted as cold points.
The method for improving the temperature uniformity of the high-temperature annealed oriented silicon steel coil is characterized in that a heat accumulator or a heating body is additionally arranged between furnace platforms (chassis) for improving the problem of the transverse temperature uniformity of the inner core of the coil, and closed-loop feedback control is performed according to a temperature thermocouple.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that the heat accumulator is a heat good conductor.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that a heat accumulator or a heating body is additionally arranged between the furnace platforms (chassis) and is arranged in the middle of the four furnace platforms (chassis) or between the two furnace platforms (chassis).
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that in order to improve the heating rate of the steel coil, an electric heating body and a temperature thermocouple are arranged between the lower part of a steel coil chassis and a furnace table, and each steel coil base electric heating body is provided with an independent regulator and performs closed-loop feedback control with thermocouple temperature measurement.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that a heating body additionally arranged between two inner covers controls the furnace temperature by adopting an independent regulator, the temperature value measured by the temperature values detected by thermocouples of the furnace top and the chassis is synthesized into an actual furnace temperature value according to the proportion within the range of 0-100%, closed loop feedback control is carried out, and then the actual furnace temperature value is compared with a process set temperature value, and the regulator at the position is controlled in a feedback mode.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that the temperature values measured by the temperature values detected by thermocouples of the furnace top and the chassis are synthesized to be 48-52%/52-48% of the actual furnace temperature value.
According to the invention, the buried even coil is annealed at high temperature in the high-temperature annealing furnace, the detected temperature is recorded by the recorder, and the buried even coil is annealed at high temperature along with the furnace like other conventional coils, and the temperature change of the buried even coil at cold and hot spots is recorded.
The results are shown in FIG. 4. It can be seen that the cold and hot spot temperature difference is up to 300 ℃ or more, and occurs in the first 20 hours of high temperature annealing. The temperature uniformity of the steel coil is reflected by the temperature change and the difference value of the hot spot and the cold spot in the high-temperature annealing process, and the temperature uniformity of the steel coil can be directly fed back by the difference value of the hot spot and the cold spot. The difference value of hot spots and cold spots is the difference value of the maximum temperatures of different parts of the steel coil.
The method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel is characterized in that a horizontal steel coil of a decarburization annealing coil is turned into a steel coil, the embedded couple temperature measurement is carried out according to the embedded couple point, then the high-temperature annealing is carried out, the temperature change and the temperature difference of the embedded couple point of the embedded couple coil are recorded, and then an insulating coating is uncoiled and coated, and the finished product is obtained after the hot stretching leveling annealing.
The invention mainly aims at the way of annealing the whole coil of the steel coil, and the thinner the steel coil is, the more the number of layers of the corresponding steel coil is, and the more the problem of uneven temperature of the steel coil is.
According to the method for improving the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel, the heating body can be an electric heating rod, a resistance belt and the like, the power can meet the process temperature requirement, the heat accumulator can quickly absorb and release heat, for example, the steel coil is a heat accumulator, and the increase of the heat accumulator can enable the temperature uniformity around the heat accumulator to be better.
According to the invention, the temperature uniformity of the steel coil in the high-temperature annealing process can also be represented by the quality of the bottom layer, the temperature difference between cold and hot points, the magnetic performance, the uniformity of the plate shape, the difference of the transverse uniformity of the iron loss and the like of the steel coil at different positions. Therefore, the temperature uniformity of the high-temperature annealed steel coil of the oriented silicon steel can be improved by the quality of the bottom layer of the finished product of the decarburization annealed steel coil, the temperature difference between cold and hot points, the magnetic performance, the uniformity of the plate shape and the difference of the transverse uniformity of the iron loss. Such as: the steel coil is externally rolled, the temperature is fast to rise, the whole is high, water is easily discharged, the bottom layer is uniform, the temperature is high, the outer ring is free, and the shape of the lower edge part is poor; the middle part of the steel coil has low temperature, difficult water drainage and additional oxidation, and watermarks or uneven bottom layers are generated; the magnetic performance can also be greatly different in different parts of the whole steel coil due to temperature difference.
Drawings
FIG. 1 is a schematic cross-sectional view of a ring annealing furnace or tunnel annealing furnace, in which: 1-a heating body is added between the inner covers; 2, adding a heating body at the lower part of the chassis; and 3, adding a heat accumulator or a heating body in the middle of the furnace table.
FIG. 2 is a schematic diagram of a high temperature annealing process of oriented silicon steel.
Fig. 3 is a schematic diagram of simulation of the internal temperature field of the vertical coil high-temperature annealed steel coil.
FIG. 4 is a schematic diagram of the arrangement of temperature measuring points in a buried even coil.
FIG. 5 is a schematic diagram of the temperature change of a buried even coil.
Fig. 6 is a schematic diagram of the position of the addition of a heat accumulator or heater between the furnace decks (chassis).
Detailed Description
The invention is further illustrated below with reference to examples.
Example 1
The decarburization annealed steel coil is produced according to a conventional oriented silicon steel manufacturing method, and the production steps comprise: smelting in a converter or an electric furnace; continuously casting into a plate blank; heating the plate blank; hot rolling; annealing the hot rolled plate; cold rolling to a thickness of 0.23 mm; decarburization annealing and nitriding treatment; after the MgO coating is applied, a decarburized annealed roll is obtained. After the horizontal steel coil is turned up to form a steel coil, performing even-embedding temperature measurement according to the even-embedding point, performing high-temperature annealing, recording the even-embedding point temperature change and the temperature difference of the even-embedding point, uncoiling, coating an insulating coating, performing hot stretching, flattening and annealing to obtain a finished product, and evaluating the uniformity of a bottom layer, magnetic performance and a plate shape of the finished product.
Comparative examples 1 to 3 were high temperature anneals in a conventional ring annealing furnace, and were large in cold and hot spot temperature difference, about 320 c, poor in uniformity of the bottom layer and the plate shape, and large in difference in lateral uniformity of the core loss, about 0.024W/kg.
Inventive examples 1-2 increased the upper and lower burners separately controlled arrangement on the basis of the conventional annular furnace, reduced the temperature difference between cold and hot spots, about 260 c, improved the uniformity of the bottom layer and plate shape, and reduced the difference in the lateral uniformity of the core loss, about 0.016W/kg.
Example 2
The decarburization annealed steel coil is produced according to a conventional oriented silicon steel manufacturing method, and the production steps comprise: smelting in a converter or an electric furnace; continuously casting into a plate blank; heating the plate blank; hot rolling; annealing the hot rolled plate; cold rolling to a thickness of 0.23 mm; decarburization annealing and nitriding treatment; after the MgO coating is applied, a decarburized annealed roll is obtained. After the horizontal steel coil is turned up to form a steel coil, performing even-embedding temperature measurement according to the even-embedding point, performing high-temperature annealing, recording the even-embedding point temperature change and the temperature difference of the even-embedding point, uncoiling, coating an insulating coating, performing hot stretching, flattening and annealing to obtain a finished product, and evaluating the uniformity of a bottom layer, magnetic performance and a plate shape of the finished product.
Comparative examples 4 to 5 were high temperature anneals in a conventional ring annealing furnace, and had a large difference in cold and hot spot temperatures of about 325 c, poor uniformity of the bottom layer and the plate shape, and a large difference in the lateral uniformity of the core loss of about 0.025W/kg.
Inventive example 3 the configuration of the heating body between the inner hoods was increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots was reduced, the uniformity of the bottom layer and the plate shape was improved at 280 ℃, the difference in the lateral uniformity of the core loss was reduced, and at 0.018W/kg.
Inventive example 4 the configuration of the lower heating body of the chassis was increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots was reduced, the uniformity of the bottom layer and the plate shape was significantly improved, the difference in the lateral uniformity of the core loss was reduced, and was 0.016W/kg.
Inventive example 5 the configuration of the heating body between the inner hood and under the chassis was increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots was significantly reduced, the uniformity of the bottom layer and the plate shape was significantly improved at 210 ℃, the difference in the lateral uniformity of the core loss was reduced, and at 0.013W/kg.
Inventive example 6 the configuration of the heat accumulator between the furnace benches was increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots was significantly reduced, the uniformity of the bottom layer and the plate shape was improved at 270 ℃, the difference of the transverse uniformity of the iron loss was reduced, and the difference was 0.017W/kg.
Inventive example 7 the configuration of the heating body between the furnace tops is increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots is obviously reduced, the uniformity of the bottom layer and the plate shape is greatly improved at 240 ℃, and the difference of the transverse uniformity of the iron loss is reduced by 0.015W/kg.
Inventive example 8 the configuration of the heating body between the inner hoods, under the chassis and in the middle of the hearth was increased on the basis of the conventional annular furnace, the temperature difference between the cold and hot spots was further reduced, the uniformity of the bottom layer and the plate shape was remarkably improved below 200 ℃, the difference in the lateral uniformity of the iron loss was further reduced, and at 0.011W/kg.
According to the invention, the temperature difference of cold and hot spots, the uniformity of the bottom layer, the magnetic performance, the uniformity of the plate shape and the difference of the transverse uniformity of the iron loss of the decarburization annealed coil finished product are evaluated, if the temperature difference of the cold and hot spots is less than 300 ℃, the uniformity of the bottom layer, the magnetic performance, the uniformity of the plate shape is better, the difference of the transverse uniformity of the iron loss is less than 0.020, and the temperature uniformity of the high-temperature annealed coil is improved.
While the above preferred embodiments have illustrated and described the present invention, it should not be construed that the invention is limited thereto. It will be apparent to those skilled in the art that various modifications and variations can be made in the above-described range without departing from the spirit of the invention or from the scope of the claims.
Claims (9)
1. A method for improving the temperature uniformity of a high-temperature annealed steel coil of oriented silicon steel, which is characterized by comprising the following steps:
In the production flow of oriented silicon steel, when the steel coil enters a high-temperature annealing process after decarburization annealing, after a horizontal steel coil is turned into a steel coil, the hot spot and the cold spot of a buried even coil are buried and subjected to even temperature measurement, then high-temperature annealing is performed through an annular annealing furnace or a tunnel annealing furnace provided with an inner cover and a chassis, the upper part burner and the lower part burner with a single control loop are subjected to closed-loop feedback separation control so as to improve the temperature of a local cold area of the steel coil and increase the burning load of a lower part burner,
And a heating body is arranged between the two inner covers so as to solve the problem of low temperature in a local area and further improve the uniformity of the steel coil in the high-temperature annealing process.
2. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 1, wherein,
The upper burner and the lower burner of the single control loop are separately controlled, the upper burner performs closed-loop feedback control according to a furnace top thermocouple, and the lower burner performs closed-loop feedback control according to a chassis thermocouple.
3. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 1, wherein,
In order to know the temperature distribution conditions of different positions of the steel coil in the high-temperature annealing process, the positions of the cold and hot spot temperatures of the steel coil after the decarburization annealing coating are subjected to embedded couple temperature measurement, wherein the position of the cold spot temperature of the embedded couple coil is the outer ring of the near end surface of the upper part of the embedded couple coil, and the position of the hot spot temperature of the embedded couple coil is the center position of the steel coil in the middle and lower parts of the embedded couple coil.
4. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 1, wherein,
In order to solve the problem of uniformity of the transverse temperature of the inner core of the steel coil, a heat accumulator or a heating body is additionally arranged between the furnace platforms, and closed-loop feedback control is performed according to a temperature thermocouple.
5. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 4,
The heat accumulator is a good heat conductor.
6. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 4,
The heat accumulator or the heating body is additionally arranged in the center or between the two furnace tables, namely the center or between the two furnace tables.
7. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 1, wherein,
In order to improve the heating rate of the steel coil, an electric heater and a temperature thermocouple are arranged between the lower part of the steel coil chassis and the furnace platform, and each steel coil base electric heater is provided with an independent regulator to perform closed-loop feedback control with thermocouple temperature measurement.
8. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 1, wherein,
The heating body between the two inner covers adopts an independent regulator to control the furnace temperature, the temperature value measured by the temperature values detected by the furnace top and the chassis thermocouples is synthesized into the actual furnace temperature value according to the proportion within the range of 0-100%, closed loop feedback control is carried out, and then the actual furnace temperature value is compared with the process set temperature value, and the regulator at the position is controlled in a feedback mode.
9. The method for improving the temperature uniformity of the high-temperature annealed steel coil of oriented silicon steel according to claim 8,
The ratio of the temperature values measured by the temperature values detected by the thermocouples of the furnace top and the chassis to the actual furnace temperature value is 48-52%:52-48%.
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