A method for stable casting of slabs with wide limit sizes in continuous casting machines

Abstract

This invention provides a method for stable casting of slabs with wide limit specifications in a continuous casting machine, belonging to the field of continuous casting technology. The method includes: dividing the casting process into a special working condition stage and a stable stage, with each stage executing preset production parameters; in the stable casting stage, correcting the production parameters based on crystallization friction and correcting deviations based on predicted deviation conditions; the correction based on predicted deviation conditions includes: determining the gap value between the slab and the roller conveyor support at each detection point using a non-contact distance sensor; using the gap value between the slab and the roller conveyor support at the target detection point, the current casting speed, and the secondary cooling water distribution as input variables, predicting the deviation direction and deviation value of the next slab segment at the target detection point using an empirical formula; and determining a correction scheme based on the deviation direction and deviation value of the next slab segment at the target detection point combined with a preset deviation safety threshold. This invention ensures casting stability by using real-time gap correction combined with predicted deviation conditions for real-time correction.

Description

Technical Field

[0001] This invention relates to the field of continuous casting technology, and in particular to a method for stable casting of slabs with a wide range of specifications in a continuous casting machine. Background Technology

[0002] With the continued growth in market demand for large-section, wide-specification continuously cast slabs, wide-specification slabs have become an important direction for steel companies to upgrade their product structure due to their ability to reduce subsequent rolling passes, lower production costs, and improve product performance uniformity. However, due to design limitations, the width of the roller conveyor in continuous casting machines is usually limited. Exceeding this limit can easily lead to blockages, scraping, or even interrupted casting during the slab transport process, seriously affecting production continuity and product quality. In existing technologies, research on wide slab continuous casting mainly focuses on crystallizer design, cooling system optimization, and casting speed control. Patent publication number CN120838836A discloses a method for producing engineering structural steel with a thickness of 4-6 mm and a width greater than 3500 mm, but it mainly focuses on the rolling process and does not address the stable casting problem of wide slabs in the continuous casting stage. The patent with publication number CN115365297A involves the flatness control of thin and wide steel plates in continuous casting, but its focus is on the tension and speed control in the later process, and it does not solve the problems of equipment adaptability and billet operation stability in the continuous casting stage.

[0003] Currently, the design width of the roller conveyor on the No. 6 continuous casting machine at a domestic steel plant is 1900mm, with the widest historical casting specification being 1850mm. To develop products with widths exceeding 1890mm, the gap between the billet and the roller conveyor is far lower than the conventional safe gap of 50-100mm. Increased frictional resistance between the billet and the copper wall of the crystallizer, as well as slight deviations in the casting trajectory, can cause the billet to become stuck on the roller conveyor or at the crystallizer exit, easily leading to casting interruptions and affecting production continuity. Existing technology lacks methods for the coordinated control of continuous casting processes and equipment under extreme gap conditions.

[0004] Therefore, there is an urgent need to develop a method for stable casting of slabs with wide limit specifications in continuous casting machines that integrates process optimization, equipment precision assurance, and intelligent control. Summary of the Invention

[0005] In view of this, the present invention provides a method for stable casting of slabs with a wide range of specifications in a continuous casting machine, which takes the collaborative control of the limit gap as the main line and builds a technical system for ensuring equipment accuracy, optimizing process parameters, and dynamically controlling the process.

[0006] Therefore, the present invention provides the following technical solution:

[0007] A method for stable casting of slabs with wide limit sizes in a continuous casting machine, comprising: The casting process is divided into a special working condition stage and a stable casting stage, and preset production parameters are executed in each stage. During the stable casting stage, the production parameters are adjusted according to the crystallization friction force, and deviation is corrected according to the predicted deviation conditions. The correction based on the predicted deviation condition includes: The gap between the billet and the roller support is determined at each detection point using a non-contact distance sensor; Using the gap between the billet and the roller support at the target detection point, the current casting speed, and the distribution of secondary cooling water as input variables, the deviation direction and deviation value of the next section of the billet at the target detection point are predicted by empirical formulas. The correction scheme is determined based on the deviation direction and deviation value of the next section of the billet at the target detection point, combined with a preset deviation safety threshold.

[0008] Furthermore, it also includes: Pre-testing of the equipment is performed before casting begins; the pre-testing includes: The roller conveyor system is precisely aligned, the narrow taper of the crystallizer is checked and aligned, and the equipment status is monitored.

[0009] Furthermore, during the stable casting stage, the production parameters are corrected based on the crystallization friction force, including: When the crystallizer friction is not within the preset range, the preset adjustment amount is reduced each time based on the current frequency. After each adjustment, it is determined whether the crystallizer friction is within the preset range. If it is within the preset range, the adjustment is stopped. If the crystallizer friction is still not within the preset range when the frequency is lowered to the preset lower limit, the waveform asymmetry coefficient is gradually adjusted. After each adjustment, it is determined whether the crystallizer friction is within the preset range. If it is within the preset range, the adjustment is stopped; if it is not within the preset range, the adjustment is stopped when the preset amplitude lower limit is reached, and confirmation is performed.

[0010] Furthermore, the gap value between the target detection point billet and the roller support includes: A non-contact ranging sensor is installed on the fixed side frame of the sector segment; The sensor at each measurement point is fixedly mounted and aligned with a fixed measurement reference target point located on the same frame and whose position is known. The horizontal distance between the reference target point and the inner wall of the frame has been pre-calibrated; The sensor measures the distance between the edge of the billet and the fixed measurement reference target point in real time; The gap between the target detection point billet and the roller support is the difference between the calibrated distance from the reference target point to the inner wall of the frame and the actual measured distance of the sensor.

[0011] Furthermore, based on the deviation direction and deviation value of the next section of the cast billet below the target detection point, combined with a preset deviation safety threshold, a correction scheme is determined, including: When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold, the cooling intensity in the opposite direction of the predicted deviation downstream of the target monitoring point is reduced. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the driving current downstream of the target detection point rises to the preset current threshold, an alarm is triggered to prompt the operator to confirm. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the total torque of the straightening machine continues to exceed the rated threshold within a preset time, an alarm is triggered to prompt the operator to confirm and to carry out emergency intervention.

[0012] Furthermore, the emergency intervention includes: Reduce the pulling speed to the preset pulling speed threshold and increase the crystallizer cooling water flow rate to the preset flow rate value; adjust the side guide plate in the opposite direction of the predicted deviation.

[0013] Furthermore, each stage executes preset production parameters, including: In special operating conditions, a non-sinusoidal waveform is used to perform crystallization vibration at the first vibration frequency and the preset vibration amplitude. During the stable casting stage, a non-sinusoidal waveform is used to induce crystallization vibration at a second vibration frequency and a preset vibration amplitude.

[0014] Furthermore, the first vibration frequency ranges from 105 to 115 times per minute; The second vibration frequency range is 115-125 times / minute; The preset vibration amplitude range is 3-5mm.

[0015] Furthermore, the special operating condition stage includes: The casting start condition and the steel grade change condition; the casting start condition includes: the time from the start of casting to the preset duration; The stable casting stage includes: the casting speed is within a preset range and the liquid level fluctuation in the crystallizer is within a preset range.

[0016] Advantages and positive effects of the present invention: This invention systematically solves the problem of jamming under extreme clearance by employing two core defense lines: precise equipment alignment before casting and dynamic anti-deviation control. It enables safe and stable production for extended periods and multiple consecutive castings even under extreme conditions where the equipment width margin does not meet existing threshold requirements, completely avoiding casting interruption accidents and ensuring the safety of personnel and equipment.

[0017] The optimized vibration and lubrication process of this invention reduces longitudinal cracks and excessive vibration marks, thereby effectively improving the surface quality of ultra-wide slabs. Dynamic anti-deviation control avoids damage to the slab shell caused by mechanical deviation correction.

[0018] This invention uses real-time gaps combined with predicted deviation conditions to perform real-time correction, ensuring the stability of casting. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Flowchart of a method for stable casting of slabs with wide limit specifications in a continuous casting machine; Figure 2 A schematic diagram of the limit gap of the roller conveyor of a continuous casting machine; Figure 3 A schematic diagram showing the optimization of the non-sinusoidal vibration waveform of the crystallizer; Figure 4 This is a schematic diagram of the dynamic anti-deviation control system for the billet's running trajectory. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] This invention provides a method for stable casting of slabs with wide limit specifications in a continuous casting machine, comprising: S1. Conduct pre-testing of equipment before casting begins; S2. Divide the casting process into a special working condition stage and a stable stage; in the special working condition stage, use a non-sinusoidal waveform with the first vibration frequency and the preset vibration amplitude to perform crystallization vibration. S3. In the stable casting stage, a non-sinusoidal waveform is used to perform crystallization vibration at the second vibration frequency and preset vibration amplitude. During the stable casting stage, production parameters are corrected according to the crystallization friction force, and deviation is corrected according to the predicted deviation conditions.

[0024] Example 1 A method for stable casting of slabs with wide limit sizes in a continuous casting machine, comprising: S1. Equipment pre-commissioning, including: precision alignment of the roller conveyor system, verification of the narrow taper and alignment of the crystallizer, and monitoring of equipment status.

[0025] 1) Precision alignment of the roller conveyor system: Before casting, the roller conveyors of all sector sections, including the curved section, arc section, straightening section, and horizontal section, are calibrated both offline and online. In this embodiment, the scheduled shutdown and maintenance windows of the continuous casting machine are utilized. These scheduled shutdown and maintenance windows include a preparation period for maintenance, overhaul, or replacement of section series.

[0026] A high-precision laser tracker was used to measure the parallelism of the axis of each row of rollers, the uniformity of the roller surface height, and the curvature deviation of the entire streamline.

[0027] After preheating the continuous casting machine, simulating the casting process, a dedicated centering template is pushed at low speed along the roller conveyor. Gap sensors installed on both sides of the template detect the gap between the template and the roller conveyor supports or side guides in real time. Based on the detection data, the adjustable sector section is adjusted online with micron-level precision to ensure the straightness of the channel under hot conditions.

[0028] 2) Crystallizer narrow face taper and centering verification: Using a test block that matches the target width, precisely verify the parallelism, opening, and taper of the narrow copper plate in the crystallizer. Ensure that the narrow copper plate is perpendicular to the wide copper plate, and that the center line of the space formed by the two narrow copper plates coincides with the center line of the casting flow, with a deviation of less than 0.5 mm.

[0029] 3) Monitoring the status of critical equipment: Test the motor current and reducer vibration of all sector drive rollers to ensure there are no abnormalities; check and tighten all fasteners of side guide plates and anti-slip rollers to eliminate uncertainties caused by equipment loosening.

[0030] S2. Divide the casting process into a special working condition stage and a stable stage; in the special working condition stage, use a non-sinusoidal waveform with the first vibration frequency and the preset vibration amplitude to perform crystallization vibration. Special working conditions include the initial casting stage and the steel replacement stage; this embodiment is the initial casting stage. During the initial casting stage, a preset production parameter set is executed to reduce the frictional resistance between the solidified billet shell and the copper plate of the crystallizer in the early stage of casting, and to prevent adhesion and uneven billet shell.

[0031] In this embodiment, the preset production parameter group includes: First frequency: set in the range of 100-130 times / minute, lower than conventional casting, to reduce the mechanical impact of vibration on the fragile billet shell.

[0032] Amplitude: Set within the range of 3-5mm, using a small amplitude to control the depth of the vibration mark and improve surface quality.

[0033] Waveform: Non-sinusoidal waveforms are used, including trapezoidal waves or composite sine waves.

[0034] S3. In the stable casting stage, a non-sinusoidal waveform is used to perform crystallization vibration at the second vibration frequency and preset vibration amplitude. During the stable casting stage, production parameters are corrected according to the crystallization friction force, and deviation is corrected according to the predicted deviation conditions.

[0035] 1. The preset production parameters for the stable casting stage in this embodiment include: Using a non-sinusoidal waveform, with a frequency of 115-125 times / minute, the same amplitude, and a waveform asymmetry coefficient of 0.48, the design goal is to control the target negative slip time to 0.11-0.13 seconds, while making the speed-time curve of the positive slip phase smoother, so as to maximize the lubrication effect of the protective slag film.

[0036] The vibration period was calculated as follows: frequency 115~125 times / minute, corresponding to period T=0.48~0.522 seconds; target negative slip time=0.11~0.13 seconds. Combining the smooth characteristics of the positive slip segment of the composite sine wave, the calculation logic of the asymmetric coefficient was modified: λ=(positive slip time-negative slip time) / vibration period, and the optimized asymmetric coefficient value was 0.45-0.51.

[0037] 2. During the stable casting stage, adjust production parameters based on crystallization friction, including: 1) Formula for calculating the friction force of the crystallizer:

[0038] in, For the real-time frictional force of the crystallizer; The system correction coefficient is used for the calibration of the hydraulic vibration system characteristics of the casting machine. The real-time average pressure of the crystallizer vibration hydraulic system is collected by the hydraulic system pressure sensor. This is the hydraulic reference pressure when the crystallizer is unloaded; it is a preset value. This represents the effective contact area of ​​the narrow-faced copper plate in the crystallizer. The asymmetry coefficient of the crystallizer vibration waveform; This is the lubrication correction factor for the liquid slag layer, calculated from the real-time thickness of the liquid slag layer. The fixed friction loss value is determined by the mechanical friction of the crystallizer itself and calibrated through an empty furnace test.

[0039] 2) During the stable casting stage, production parameters are adjusted based on the crystallization friction, including: When the crystallizer friction force is not within the preset range, the preset adjustment amount is lowered each time based on the current frequency. After each adjustment, it is determined whether the crystallizer friction force is within the preset range. If it is within the preset range, the adjustment is stopped. If it is still not within the preset range even after lowering to the preset lower limit of the frequency, the waveform asymmetry coefficient is gradually adjusted. After each adjustment, it is determined whether the crystallizer friction force is within the preset range. If it is within the preset range, the adjustment is stopped. If it is not within the preset range, the adjustment is stopped when it reaches the preset lower limit of the amplitude, and then confirmation is performed.

[0040] 3. Correct deviations based on predicted deviation conditions, including: The gap between the billet and the roller support is determined at each detection point using a non-contact distance sensor; Using the gap between the billet and the roller support at the target detection point, the current casting speed, and the distribution of secondary cooling water as input variables, the deviation direction and deviation value of the next section of the billet at the target detection point are predicted by empirical formulas. The correction scheme is determined based on the deviation direction and deviation value of the next section of the billet at the target detection point, combined with the preset deviation safety threshold.

[0041] 1) Determine the gap value between the billet and the roller conveyor support at the target inspection point, including: Non-contact ranging sensors are installed on the fixed side frame of the sector segment; the sensor at each measuring point is firmly installed and aligned with a fixed measuring reference target point located on the same frame and whose position is known; the horizontal distance between the reference target point and the inner wall of the frame has been pre-calibrated; the sensor measures the distance between the edge of the billet and the fixed reference target point in real time; the gap between the billet at the target detection point and the roller support is the difference between the calibrated distance from the reference target point to the inner wall of the frame and the actual distance measured by the sensor.

[0042] 2) Determine the correction scheme based on the deviation direction and deviation value of the next section of the cast billet at the target detection point, combined with the preset deviation safety threshold, including: When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold, the cooling intensity in the opposite direction of the predicted deviation downstream of the target monitoring point is reduced. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the driving current downstream of the target detection point rises to the preset current threshold, an alarm is triggered to prompt the operator to confirm. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the total torque of the straightening machine continuously exceeds the rated threshold within a preset time, an alarm is triggered to prompt the operator to confirm and to initiate emergency intervention. Emergency intervention includes: reducing the casting speed to the preset casting speed threshold, increasing the coolant flow rate of the crystallizer to the preset flow rate value, and adjusting the side guide plates in the opposite direction of the predicted deviation.

[0043] Example 2 Combination Figure 2 As shown, based on the characteristics and production requirements of a No. 6 continuous casting machine in a steel plant, with a roller conveyor design width of 1900mm and an original maximum casting width of 1850mm, this method addresses the risks of blockage and interruption in casting slabs with a maximum width of 1890mm. The implementation process includes: The casting machine No. 6 is currently casting Q355B low alloy structural steel, with a slab thickness of 230mm, a width of 1890mm, and a casting temperature of 1520-1540℃.

[0044] S1. Before implementation, confirm that the casting machine is in the planned shutdown and maintenance window, and complete the basic inspection and calibration of all key equipment. The accuracy of the No. 6 casting machine equipment system is fully calibrated to ensure the accuracy of key equipment such as the No. 6 casting machine roller conveyor and crystallizer under hot conditions, and to reserve a stable operating clearance for the 1890mm slab.

[0045] 1) Precision alignment of the roller conveyor system: A high-precision laser tracker was used to perform full-process measurements on the roller conveyor of 15 fan-shaped sections of the No. 6 casting machine, including the bending section (sections 1-3 in this embodiment), the arc section (sections 4-8 in this embodiment), the straightening section (sections 9-10 in this embodiment), and the horizontal section (sections 11-15 in this embodiment). The focus was on checking the parallelism of the roller axis, the consistency of the roller surface height, and the deviation of the streamline curvature for each row of rollers.

[0046] After offline calibration, the preheating program for casting machine No. 6 was started, and the temperature was raised to 300℃ according to the conventional preheating curve to simulate the casting process. A custom-made 1890mm wide centering template was pushed along the roller conveyor at a low speed of 0.2m / min. Gap sensors were installed on both sides of the template, with a measurement accuracy of ±0.01mm, to detect the gap between the template and the roller conveyor supports on both sides in real time. Based on the test data, the adjustable sector sections No. 5 and No. 8 were adjusted at the micron level to ultimately ensure the straightness of the slab running channel under hot conditions. 0.3mm, minimum gap on both sides 5mm. 2) Crystallizer narrow face taper and centering verification: The parallelism, aperture, and taper of the narrow copper plates on the crystallizer are checked to ensure that the parallelism deviation of the narrow copper plates on both sides is correct. 0.1mm, opening degree error 0.2mm; the taper should be set at 0.8-1.2% / m.

[0047] S2. Divide the casting process into a special working condition stage and a stable stage; in the special working condition stage, use a non-sinusoidal waveform with the first vibration frequency and the preset vibration amplitude to perform crystallization vibration. It adopts a low-frequency, small-amplitude, asymmetric waveform vibration mode; In this embodiment, the initial casting stage is defined as the first 30 minutes of casting. The parameter combination for the initial casting and steel grade change stages is: trapezoidal wave, frequency 110 times / minute, amplitude 4mm, waveform asymmetry coefficient 0.55, and target negative slip time 0.15 seconds. This is used to strengthen the initial billet shell and prevent billet shell cracking.

[0048] S3. In the stable casting stage, a non-sinusoidal waveform is used to perform crystallization vibration at the second vibration frequency and preset vibration amplitude. During the stable casting stage, production parameters are corrected according to the crystallization friction force, and deviation is corrected according to the predicted deviation conditions.

[0049] 1. In this embodiment, the stable casting stage is defined as the casting speed being stable at 1.0-1.1 m / min and the liquid level fluctuation in the crystallizer being ≤ ±3 mm.

[0050] The parameter combination for the stable casting stage is: composite sine wave, frequency 120 Hz, amplitude 4 mm, waveform asymmetry coefficient 0.48, and target negative slip time 0.12 seconds. The waveforms are as follows: Figure 3 As shown.

[0051] 2. During the stable casting stage, the vibration frequency and waveform asymmetry coefficient are corrected based on the frictional force of the crystallizer: Calculate the frictional force of the crystallizer:

[0052] In this embodiment, The real-time frictional force of the crystallizer is controlled within the target range of 8-12 kN; The system correction coefficient, based on the calibration of the hydraulic vibration system characteristics of casting machine No. 6, is set to 0.85-0.95. The real-time average pressure of the crystallizer vibration hydraulic system is collected by the hydraulic system pressure sensor, with a measurement range of 0-25MPa. The hydraulic reference pressure of the crystallizer when there is no load is preset to 1.2MPa (this is the reference pressure of the vibration system when there is no friction load in the empty furnace state, and it is calibrated by empty furnace debugging before implementation). The effective contact area of ​​the narrow-face copper plate in the crystallizer, calculated for a slab 1890mm wide and 250mm thick, is... (Fixed value, matching the target slab specifications); The asymmetry coefficient of the crystallizer vibration waveform is synchronized with the current vibration parameters in real time (parameter group 2, stable casting stage, initial value 0.48, dynamically changes within the range of 0.46-0.50 during automatic adjustment). The lubrication correction coefficient for the liquid slag layer is derived from the real-time thickness of the liquid slag layer. A liquid slag layer thickness of 10-15mm corresponds to... (During this implementation, the liquid slag layer remained stable at 12-14 mm.) (Real-time value range: 0.98-1.05) The fixed friction loss value is the mechanical friction of the crystallizer itself (such as the copper plate and the guide mechanism), which is calibrated by empty furnace testing and is fixed at 1.2kN.

[0053] When the frictional force of the crystallizer is not within the preset range, then: Based on the current frequency, the frequency is reduced by 0.5% each time. In this embodiment, when the frequency is 120 times / minute, the frequency is reduced by 0.6 times / minute each time. The maximum reduction is no more than 2%. In this embodiment, the maximum reduction is 117.6 times / minute. After each adjustment, observe for 30 seconds. If the crystallizer friction is still not within the normal range, continue to adjust until the lowest frequency threshold is reached. If this is not met, adjust the current waveform asymmetry coefficient by 0.005 each time, with a maximum adjustment of no more than 0.02.

[0054] 3. Selection of protective slag and control of liquid slag layer A highly lubricating protective slag specifically designed for 1890mm ultra-wide slabs is selected, with a viscosity ≤0.6Pa·s (1300℃). The thickness of the liquid slag layer is monitored in real time using reverse propagation of the crystallizer heat flow and insertion thermocouples, and is stably controlled within the ideal range of 10-15mm. This is achieved by adjusting the amount and frequency of protective slag addition, ensuring continuous and sufficient lubrication.

[0055] 4. Correct deviations based on predicted deviation conditions, including: The principle of the dynamic anti-deviation control system for billet movement trajectory is as follows: Figure 4 As shown.

[0056] 1) Determine the gap value between the billet and the roller conveyor support at the target inspection point, including: Laser rangefinders are installed at key locations along the casting flow direction of casting machine No. 6, such as the fixed side frames of sector sections No. 3, 7, and 11.

[0057] Each sensor is aligned with a fixed reference target on the same frame, and the distance from the reference target to the inner wall of the frame is pre-calibrated to measure the distance between the edge of the billet and the reference target in real time. The gap between the billet and the roller support at the detection point is the difference between the distance between the edge of the billet and the reference target point and the actual distance measured by the sensor.

[0058] 2) Based on the current data: the gap on the left side of sector 7 continues to decrease at a rate of 0.2 mm / min, the casting speed is 1.05 m / min, and the secondary cooling water volume distribution is 28 L / min on the left and 27 L / min on the right. The amount and direction of billet deviation within the next 2 meters are predicted using empirical formulas.

[0059] 3) In this embodiment, the gap threshold is 6mm. When the real-time gap on the left side of sector 7 drops to 5.8mm, it is predicted that the billet will tend to deviate to the left. The cooling intensity of the secondary cooling nozzle on the right side is increased from 27L / min to 28.5L / min. The difference in shrinkage stress of the billet shell is used to assist in correction. The whole process is without mechanical damage and the deviation is corrected quickly.

[0060] The following signals are collected in real time through the PLC system: main motor current and torque of the straightening machine, drive motor current of each sector segment, crystallizer vibration data, deviation data of 3 measuring points, and crystallizer friction force, for a total of 24 signals.

[0061] Level 1 warning: Triggered when the gap on the left side of sector segment 7 is less than 6mm and the drive current of sector segment 8 downstream increases by 15% year-on-year. One Level 1 warning was triggered during this implementation; the operator immediately strengthened inspections, and no further abnormalities were found.

[0062] Level 2 warning: Triggered when the total torque of the leveling machine exceeds 85% of the rated value for 5 consecutive seconds or the gap at any point is <4mm. This implementation did not trigger the Level 2 warning; the preset emergency intervention procedure is as follows: a) Reduce the pulling speed by 0.1-0.2 m / min; b) Briefly increase the crystallizer cooling water flow rate by approximately 5%; c) Fine-tune the relevant side guide plates in the opposite direction of the predicted deviation. After the abnormal signal disappears, gradually restore the original process.

[0063] In this embodiment, the pulling speed is reduced by 0.15 m / min, the cooling water flow rate of the crystallizer is increased by 5%, and the side guide plate is finely adjusted.

[0064] Using this method, 15 heats of 1890mm wide slabs were successfully produced on Casting Machine No. 6, with a total casting time of 32 hours. The following results were achieved: no jamming or interruption of casting, and 100% production continuity; excellent slab surface quality, with defects such as edge cracks and slag inclusions occurring at a rate of ≤0.3% (better than the 0.8% of the conventional 1850mm specification); dimensional accuracy of the hot slabs met the standards (width deviation ±3mm, thickness deviation ±2mm); and the pressure of delivering large-section products was alleviated, with single-heat output increasing by 2.2% compared to the 1850mm specification.

[0065] This implementation method is fully adapted to the characteristics of No. 6 casting machine. Through the coordinated operation of each step, the risk of casting at the limit specifications is effectively controlled, which can provide a reference for the development of wide limit specification products for similar continuous casting machines.

[0066] This embodiment proposes a systematic methodology and combined techniques, rather than relying on a single specific piece of equipment. Its framework of precision assurance, process optimization, and dynamic monitoring is applicable to various slab continuous casting machines facing casting widths approaching equipment limits, and has broad industry application prospects.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of stable casting of a slab of a wide limit gauge of a continuous casting machine, characterized by, include: The casting process is divided into a special working condition stage and a stable casting stage, and preset production parameters are executed in each stage. During the stable casting stage, the production parameters are adjusted according to the crystallization friction force, and deviation is corrected according to the predicted deviation conditions. The correction based on the predicted deviation condition includes: The gap between the billet and the roller support is determined at each detection point using a non-contact distance sensor; Using the gap between the billet and the roller support at the target detection point, the current casting speed, and the distribution of secondary cooling water as input variables, the deviation direction and deviation value of the next section of the billet at the target detection point are predicted by empirical formulas. The correction scheme is determined based on the deviation direction and deviation value of the next section of the billet at the target detection point, combined with the preset deviation safety threshold. During the stable casting stage, the production parameters are adjusted based on the crystallization friction force, including: When the crystallizer friction is not within the preset range, the preset adjustment amount is reduced each time based on the current frequency. After each adjustment, it is determined whether the crystallizer friction is within the preset range. If it is within the preset range, the adjustment is stopped. If the crystallizer friction is still not within the preset range when the frequency is lowered to the preset lower limit, then the waveform asymmetry coefficient is gradually adjusted. After each adjustment, it is determined whether the crystallizer friction is within the preset range. If it is within the preset range, the adjustment is stopped; if it is not within the preset range, the adjustment is stopped when the preset amplitude lower limit is reached, and then confirmation is performed. Based on the deviation direction and deviation value of the next section of the billet below the target detection point, and in conjunction with a preset deviation safety threshold, a correction scheme is determined, including: When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold, the cooling intensity in the opposite direction of the predicted deviation downstream of the target monitoring point is reduced. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the driving current downstream of the target detection point rises to the preset current threshold, an alarm is triggered to prompt the operator to confirm. When the gap between the billet and the roller support at the target detection point is lower than the preset safety threshold and the total torque of the straightening machine continues to exceed the rated threshold within a preset time, an alarm is triggered to prompt the operator to confirm and emergency intervention is carried out. The emergency intervention includes: Reduce the pulling speed to the preset pulling speed threshold and increase the crystallizer cooling water flow rate to the preset flow rate value; adjust the side guide plate in the opposite direction of the predicted deviation direction; Each stage executes preset production parameters, including: In special operating conditions, a non-sinusoidal waveform is used to perform crystallization vibration at the first vibration frequency and the preset vibration amplitude. During the stable casting stage, a non-sinusoidal waveform is used to induce crystallization vibration at a second vibration frequency and a preset vibration amplitude.

2. The method of claim 1, wherein, Also includes: Pre-testing of equipment should be carried out before casting begins; The pre-debugging includes: The roller conveyor system is precisely aligned, the narrow taper of the crystallizer is checked and aligned, and the equipment status is monitored.

3. The method of claim 1, wherein, The gap value between the target detection point billet and the roller support includes: A non-contact ranging sensor is installed on the fixed side frame of the sector segment; The sensor at each measurement point is fixedly mounted and aligned with a fixed measurement reference target point located on the same frame and whose position is known. The horizontal distance between the reference target point and the inner wall of the frame has been pre-calibrated; The sensor measures the distance between the edge of the billet and the fixed measurement reference target point in real time; The gap between the target detection point billet and the roller support is the difference between the calibrated distance from the reference target point to the inner wall of the frame and the actual measured distance of the sensor.

4. The method of claim 1, wherein, The first vibration frequency ranges from 105 to 115 times per minute; The second vibration frequency range is 115-125 times / minute; The preset vibration amplitude range is 3-5mm.

5. The method of claim 1, wherein, The special operating condition phase includes: The casting start condition and the steel grade change condition; the casting start condition includes: the time from the start of casting to the preset duration; The stable casting stage includes: the casting speed is within a preset range and the liquid level fluctuation in the crystallizer is within a preset range.

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