System and method for controlling surface quality of small cross-section billet production of bearing steel

Abstract

This invention provides a system and method for controlling the surface quality of bearing steel produced from small-section cast billets, belonging to the field of iron and steel smelting technology. It includes spray nozzles, an infrared temperature measuring device, and a control module. The control module is used to predict the billet shell thickness distribution and surface thermal stress distribution in real time based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, using a solidification thermal stress coupling model. Based on the billet shell thickness distribution and the surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, it predicts in real time the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles in the corner and center regions of the billet. The system controls the spray nozzles to adjust the opening of the flow regulating valves and the mechanical deflection angle in real time according to the predicted target cooling water deflection angle and target cooling water flow rate, thereby spraying cooling water onto the billet. This invention achieves precise control of the cooling intensity and cooling range of the cast billet.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a system and method for controlling surface quality of small-section billet bearing steel. BACKGROUND

[0002] As a core material for manufacturing mechanical bearings, the service performance of bearing steel is highly dependent on the cleanliness, microstructure uniformity and surface integrity of the steel. With the wide application of continuous casting technology, small-section billets have become the mainstream process for producing bearing steel due to high production efficiency and low cost.

[0003] However, small-section billets face more severe surface quality control challenges than large-section billets during solidification: the high specific surface area leads to a dramatic increase in cooling intensity, and the non-uniformity of the primary shell is amplified. In addition, the high-carbon and high-alloy characteristics of bearing steel make it extremely susceptible to surface defects under the coupling of solidification shrinkage, phase transformation stress and thermal mechanical action.

[0004] Continuous casting is a core process in steel production, and the secondary cooling (referred to as "secondary cooling") process has a decisive influence on the surface and internal quality of the billet, especially for high-value-added steel. For high-carbon and high-chromium alloy steels such as bearing steel, they are extremely sensitive to non-metallic inclusions, carbide segregation and surface cracks, so extremely strict requirements are placed on uniform cooling and control during continuous casting.

[0005] In recent years, to improve production efficiency and reduce cost, the production process of small-section billets (square billets with a side length less than 200 mm) has become increasingly popular. However, small-section billets have a larger specific surface area, and their solidification behavior in the secondary cooling zone is fundamentally different from that of large-section billets: the cooling intensity increases dramatically, the temperature gradient at the solidification front is steep, and the non-uniformity of the primary shell is significantly amplified by the geometric effect. Specifically, the corners of the billet are prone to severe undercooling due to two-dimensional heat dissipation, which can induce transverse cracks or corner cracks; while the center of the billet (or the center of the wide face) is prone to coarse structure, loose center or even internal cracks due to heat convergence and insufficient cooling. This contradiction between corner undercooling and center undercooling is a key process problem that restricts the quality stability of small-section bearing steel billets.

[0006] To control the quality of the billet, the traditional continuous casting secondary cooling control technology mainly follows the following modes: Static water distribution model: a fixed cooling water table is set according to the steel grade, section and real-time casting speed of the caster. This method cannot respond to the fluctuations in the production conditions (such as changes in the real-time casting speed of the caster and fluctuations in the tundish temperature), and for small-section bearing steel which is sensitive to solidification characteristics, the control effect is rough and the quality risk is high.

[0007] Dynamic control based on real-time surface temperature feedback: This is the current mainstream technology. Infrared thermometers installed in each section of the secondary cooling zone detect the real-time surface temperature of the billet and compare it with a preset target temperature curve. Algorithms such as PID control are then used to dynamically adjust the total water volume in that cooling section. While an improvement over static models, its core flaw lies in its "homogeneous" control approach—treating the billet within a cooling section as a single unit for temperature regulation, failing to recognize and respond to the inherent, significant heat dissipation differences between corners and the center of the surface. This "egalitarian" control often comes at the cost of sacrificing corner quality (which may still result in overcooling) or center-of-surface quality (which may still result in undercooling).

[0008] Advanced Models and Intelligent Control: Existing technologies have yielded more complex solutions, such as using three-dimensional temperature field models for online simulation or introducing artificial intelligence algorithms to predict optimal water volume. These technologies improve the overall accuracy of temperature control. However, their control objectives still focus on "uniformity of the temperature field," and the control methods are mostly limited to "single-dimensional adjustment of water volume." For small-section bearing steel, the core problem stems from the inherent uneven heat dissipation caused by its geometry. Simply adjusting the water volume cannot simultaneously solve the two-dimensional problems of "over-cooling" at the corners and "insufficient cooling" at the center. Furthermore, these systems are typically complex and expensive, and lack self-sensing and fault-tolerant capabilities regarding the working condition of the spray nozzles themselves (such as blockage or wear).

[0009] Existing actuators in the secondary cooling zone, namely spray nozzles, are primarily designed with a focus on atomization and water flow density distribution. While adjustable spray nozzles (e.g., those with pneumatically adjustable openings) and fixed nozzles at different angles are available, there is a lack of intelligent actuators capable of synchronously and collaboratively and precisely adjusting the "cooling intensity" (flow rate) and "cooling spatial distribution" (water flow impact angle and coverage area) based on the real-time thermal state of local micro-regions (corners and face centers) of the cast billet. Decoupling and independently controlling the flow rate and impact angle of the cooling water, and integrating this with the evolution of material solidification stress, is a feat that has not yet been effectively achieved in existing technologies.

[0010] Therefore, developing an intelligent cooling control system specifically designed for the solidification characteristics of small-section bearing steel billets, capable of zoning, multivariate operation, and stress prediction, is of urgent industrial demand for overcoming surface quality bottlenecks and achieving efficient and stable continuous casting production of high-quality bearing steel. Summary of the Invention

[0011] The purpose of this invention is to address the shortcomings of existing technologies by providing a system for controlling the surface quality of bearing steel produced from small-section cast billets, comprising: The spray nozzle, infrared temperature measuring device, and control module are included. The opening degree of the flow regulating valve and the mechanical deflection angle of the spray nozzle can be adjusted. The infrared temperature measuring device is used to measure the real-time surface temperature of the corner area and the center area of ​​the billet. Multiple spray nozzles form an array, with some spray nozzles used to cool the corner areas of the billet and others used to cool the center area of ​​the billet. The control module is used to predict the thickness distribution and surface thermal stress distribution of the billet shell in the corner and center regions in real time based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, using a solidification thermal stress coupling model. Based on the thickness distribution and surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, the module predicts the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles in the corner and center regions of the billet in real time. The module controls the spray nozzles to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

[0012] Furthermore, in the control module, based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, a solidification thermal stress coupling model is used to predict in real time the billet shell thickness distribution and surface thermal stress distribution in the corner and center regions of the billet. The specific method is as follows: The formula for the solidification thermal stress coupling model is as follows: Define the convection term as Define the initial boundary conditions as follows ; in, It is the Hamiltonian operator. It is the density of bearing steel at the corresponding temperature. This is the specific heat capacity of bearing steel at a corresponding temperature. It is the thermal conductivity of bearing steel at the corresponding temperature. It is the latent heat of solidification of bearing steel. It is the liquidus temperature of bearing steel. It is the real-time casting speed. These are the spatial coordinates of the billet width direction, thickness direction, and billet pulling direction, respectively. It is a time-varying variable. yes At all times, the top point of the cast billet Real-time surface temperature of the billet, point Real-time surface temperature based on point The location includes the real-time surface temperature of the corner area and the center area. It is the initial real-time surface temperature of the billet when it enters the secondary cooling zone. It refers to the real-time superheat of molten steel. yes At all times, the top point of the cast billet solid fraction, Specifically as follows: in, It is the solidus temperature of bearing steel. It is the solid fraction-temperature function corresponding to the equilibrium phase diagram of bearing steel; Real-time surface temperature of the corner and center areas of the cast billet Real-time casting speed Input the convection term, and the real-time superheat of the molten steel. Solve for the initial boundary conditions of the input variables At all times, the top point of the cast billet solid fraction ; in, yes At all times, the top point of the cast billet Surface thermal stress, It is the elastic modulus of bearing steel at the corresponding temperature. It is the coefficient of thermal expansion of bearing steel at the corresponding temperature. It is the solidification shrinkage coefficient of bearing steel at the corresponding temperature; in, yes At all times, the top point of the cast billet The thickness of the blank shell, It is the growth coefficient of the billet shell. yes At all times, the top point of the cast billet from The time taken to move to the current position. Real-time casting speed Decide, yes At all times, the top point of the cast billet The local convective cooling coefficient.

[0013] Furthermore, the formula for calculating the target cooling water flow rate in the control module is as follows: in, yes At all times, the top point of the cast billet The target cooling water flow rate corresponding to the spray nozzle. It is the baseline rated flow rate. It is the benchmark casting speed for continuous casting production. It is the benchmark superheat for continuous casting production. It is an index of the impact of pulling speed on cooling water flow rate. It is an index of the impact of superheat on cooling water flow rate. It is the cooling water flow rate correction factor for surface thermal stress deviation. It is a point on the cast billet The corresponding surface thermal stress safety threshold, It is the cooling water flow rate correction factor for the billet shell thickness. It is a point on the cast billet The corresponding blank thickness safety threshold, the surface thermal stress safety threshold and the blank shell thickness safety threshold According to the point The location has a preset value.

[0014] Furthermore, in the control module, the formula for calculating the target cooling water deflection angle is as follows: in, yes At all times, the top point of the cast billet The target cooling water deflection angle corresponding to the spray nozzle. It is the reference deflection angle. It is the coefficient of influence of pulling speed on the deflection angle of cooling water. It is the coefficient of influence of superheat on the deflection angle of cooling water. It is the cooling water deflection angle correction factor for surface thermal stress deviation. It is the cooling water deflection angle correction coefficient for the billet shell thickness deviation.

[0015] Furthermore, in the control module, the specific method for controlling the spray nozzles to adjust the opening of the flow regulating valve in real time according to the real-time predicted target cooling water flow rate is as follows: In the formula, This is the pipe radius of the corresponding spray nozzle. It is the dynamic viscosity of the cooling water. This is the channel length of the corresponding spray nozzle. It is pi. It is the friction coefficient. This refers to the pipe diameter of the corresponding spray nozzle. It is the current local resistance coefficient of the flow control valve. It is the pressure difference between the inlet and outlet of the cooling water in the spray nozzle. , It is the pressure loss that overcomes the viscous friction along the pipe wall when the cooling water flows in the spray nozzle channel. It is the local pressure loss caused by the contraction, expansion and eddy currents of the flow channel when cooling water passes through the flow regulating valve; Based on the real-time predicted target cooling water flow rate of the spray nozzle Solve for the current local resistance coefficient of the flow control valve. The local resistance coefficient of the regulating valve is adjusted according to the flow rate. Calculate the opening degree of the flow control valve. The formula is as follows: = in, It is the effective flow area of ​​the flow regulating valve at its current opening degree. This is the rated flow area when the flow regulating valve is fully open. yes The corresponding local resistance coefficient of the flow regulating valve; Adjust the valve opening according to the flow rate. This is used to adjust the effective flow area of ​​the flow regulating valve at its current opening. .

[0016] Furthermore, in the control module, the specific method for controlling the spray nozzles to adjust the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle is as follows: In the formula, yes At all times, the top point of the cast billet The mechanical deflection angle corresponding to the spray nozzle; The target cooling water deflection angle of the spray nozzle is predicted in real time. Solve for the mechanical deflection angle of the spray nozzle. This is to adjust the mechanical deflection angle of the spray nozzle.

[0017] Furthermore, the aforementioned At all times, the top point of the cast billet Local convection cooling coefficient The calculation formula is as follows: in, It is the heat transfer correction factor. yes At all times, the top point of the cast billet Corresponding to the actual cooling water flow rate of the spray nozzle, It is the cooling water flow rate index. It is the mechanical deflection angle index. yes At all times, the top point of the cast billet The corresponding actual cooling water spray angle yes At all times, the top point of the cast billet The vertical distance from the spray nozzle outlet to the surface of the cast billet. The diffusion coefficient of the cooling water jet is denoted as .

[0018] Furthermore, the flow regulating valve is a shape memory alloy valve, and the control module changes the effective flow area by adjusting the shape memory alloy valve. This is used to adjust the opening of the flow regulating valve.

[0019] A method for controlling the surface quality of bearing steel produced from small-section cast billets includes: Based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, a solidification thermal stress coupling model is used to predict the billet shell thickness distribution and surface thermal stress distribution in the corner and center regions in real time. Based on the billet shell thickness distribution and the surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles in the corner and center regions of the billet are predicted in real time. The spray nozzles are controlled to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

[0020] A computer program product includes a computer program / instructions that, when executed by a processor, implement the calculation process of the control module in the above-described method for controlling the surface quality of bearing steel produced from small-section cast billets.

[0021] The beneficial effects of this invention are as follows: 1. This invention uses the real-time surface temperature of the cast billet collected by an infrared thermometer as the feedback core, and the real-time casting speed and the real-time superheat of the molten steel as feedforward inputs. Through a solidification thermal stress coupling model, it achieves advanced and accurate prediction of the solid fraction, shell thickness, and surface thermal stress of the cast billet. Based on the prediction results, it dynamically solves the target cooling water flow rate and deflection angle, replacing the traditional empirical control of static water distribution. It can respond in real time to disturbances in the entire process, such as fluctuations in the real-time casting speed and changes in the real-time superheat of the molten steel, solving the problems of strong lag and poor adaptability of traditional control, and ensuring the long-term stability of the cast billet quality throughout the continuous casting process.

[0022] 2. This invention employs a dual-actuator mechanism that adjusts the cooling water flow rate by changing the opening of the flow regulating valve and the cooling water spray angle by adjusting the mechanical deflection angle of the spray nozzle. This achieves independent decoupling and coordinated control of cooling intensity and cooling coverage. By adjusting the cooling water flow rate to match the overall cooling requirements of the billet, and by adjusting the cooling water spray angle to precisely adapt to the differentiated heat dissipation characteristics of the corners and face centers, this invention offers greater flexibility and precision compared to traditional single-dimensional control that can only adjust the water volume. Furthermore, it establishes a precise conversion relationship between the cooling water flow rate and the opening of the flow regulating valve, eliminating control errors caused by the nonlinearity and execution deviation of the flow regulating valve, and ensuring the accurate implementation of control commands. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the mechanical structure of the system for controlling the surface quality of bearing steel produced from small-section cast billets in this invention.

[0024] Figure 2 This is a schematic diagram showing the mechanical deflection angle of the spray nozzle and the deflection angle of the cooling water.

[0025] Figure 3 This is a logic block diagram of the system for controlling the surface quality of bearing steel produced from small-section cast billets in this invention.

[0026] Explanation of reference numerals in the attached drawings: 1-Shell; 2-Cooling water pipe; 3-Infrared temperature measuring device; 4-Spray nozzle; 5-Cast surface; L-Cooling water direction; - Actual cooling water spray angle; - The mechanical deflection angle of the spray nozzle. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] Example 1 A system for controlling the surface quality of bearing steel produced from small-section cast billets, referenced Figure 1 and Figure 3 ,include: The system includes a housing 1, a cooling water pipe 2, an infrared temperature measuring device 3, several spray nozzles 4, and a control module. The spray nozzles 4 are installed on the wall of the housing 1. The opening degree of the flow regulating valve and the mechanical deflection angle of the spray nozzles 4 can be adjusted. The cooling water pipe 2 is installed on the wall of the housing 1, and the infrared temperature measuring device 3 is installed on the surface of the housing 1. Cooling water pipe 2 is used to guide cooling water into the interior of housing 1 and provide a certain water pressure to supply water to spray nozzle 4; Infrared temperature measuring device 3 is used to measure the real-time surface temperature of the corner area and the center area of ​​the cast billet. Multiple spray nozzles 4 form an array, with some spray nozzles 4 used to cool the corner area of ​​the billet and others used to cool the center area of ​​the billet. The control module is used to predict the thickness distribution and surface thermal stress distribution of the billet shell in the corner and center regions of the billet in real time, based on the real-time surface temperature of the casting machine and the real-time superheat of the molten steel, using a solidification thermal stress coupling model. Based on the billet shell thickness distribution and the surface thermal stress distribution, and again based on the real-time casting machine speed and the real-time superheat of the molten steel, the module predicts the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles 4 in the corner and center regions of the billet in real time. The module controls the spray nozzles 4 to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

[0029] By independently controlling the flow rate and deflection angle of the spray nozzles 4 in the corner and center areas, the problems of corner overcooling and cracking and slow heat dissipation in the center area are specifically addressed, fundamentally improving the surface quality of the bearing steel billet. Real-time temperature data is fed back via infrared thermography, and the control module uses this data to dynamically adjust parameters through equation calculations, replacing traditional static, experience-based cooling and avoiding quality defects caused by temperature fluctuations.

[0030] As a specific implementation method, the control module uses a solidification thermal stress coupling model to predict the shell thickness distribution and surface thermal stress distribution in the corner and center regions of the billet in real time, based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel. The formula for the solidification thermal stress coupling model is as follows: Define the convection term as Define the initial boundary conditions as follows ; in, It is the Hamiltonian operator. It is the density of bearing steel at the corresponding temperature. This is the specific heat capacity of bearing steel at a corresponding temperature. It is the thermal conductivity of bearing steel at the corresponding temperature. It is the latent heat of solidification of bearing steel. It is the liquidus temperature of bearing steel. It is the real-time casting speed. These are the spatial coordinates of the billet width direction, thickness direction, and billet pulling direction, respectively. It is a time-varying variable. yes At all times, the top point of the cast billet Real-time surface temperature of the billet, point Real-time surface temperature based on point The location includes the real-time surface temperature of the corner area and the center area. It is the initial real-time surface temperature of the billet when it enters the secondary cooling zone. It refers to the real-time superheat of molten steel. yes At all times, the top point of the cast billet solid fraction, Specifically as follows: in, It is the solidus temperature of bearing steel. It is the solid fraction-temperature function corresponding to the equilibrium phase diagram of bearing steel. This function is the inherent material property of bearing steel (such as mainstream GCr15), which is directly derived from the equilibrium phase diagram of bearing steel and is publicly available data in the industry. Real-time surface temperature of the corner and center areas of the cast billet Real-time casting speed Input the convection term, and the real-time superheat of the molten steel. Solve for the initial boundary conditions of the input variables At all times, the top point of the cast billet solid fraction ; in, yes At all times, the top point of the cast billet Surface thermal stress, It is the elastic modulus of bearing steel at the corresponding temperature. It is the coefficient of thermal expansion of bearing steel at the corresponding temperature. It is the solidification shrinkage coefficient of bearing steel at the corresponding temperature; in, yes At all times, the top point of the cast billet The thickness of the blank shell, It is the growth coefficient of the billet shell. yes At all times, the top point of the cast billet from The time taken to move to the current position. Real-time casting speed Decide, yes At all times, the top point of the cast billet The local convective cooling coefficient.

[0031] in, It is the heat transfer correction factor. yes At all times, the top point of the cast billet Corresponding to the actual cooling water flow rate of spray nozzle 4, It is the cooling water flow rate index. It is the mechanical deflection angle index. yes At all times, the top point of the cast billet The corresponding actual cooling water spray angle yes At all times, the top point of the cast billet The vertical distance from the outlet of spray nozzle 4 to the surface of the cast billet. The diffusion coefficient of the cooling water jet is denoted as .

[0032] Specifically, the first step is to collect and preprocess the model input parameters in real time. The real-time surface temperature of the entire cross-section of the billet, including the corner and center areas, is collected using an infrared thermometer, while the real-time casting speed is simultaneously obtained from the casting machine control system. The real-time superheat of molten steel is obtained from the tundish temperature measurement system. Simultaneously, retrieve the pre-stored basic thermophysical and mechanical properties of the target bearing steel, including the density of the bearing steel at the corresponding temperature. Specific heat capacity of bearing steel at corresponding temperatures Thermal conductivity of bearing steel at corresponding temperatures Latent heat of solidification of bearing steel Liquidus temperature of bearing steel Solidus temperature of bearing steel Elastic modulus of bearing steel at corresponding temperatures The coefficient of thermal expansion of bearing steel at corresponding temperatures The solidification shrinkage coefficient of bearing steel .

[0033] The second step involves real-time tracking of the solidification front and the solidification distribution. Based on the solved transient temperature field across the entire cross-section, the solidification distribution is calculated point-by-point according to the piecewise function of solidification-temperature for bearing steel: when... > hour, At all times, the top point of the cast billet solid fraction It is determined to be in the liquid phase region; when ≤ ≤ At that time, the solid fraction is calculated using the solid fraction-temperature function corresponding to the equilibrium phase diagram of bearing steel. It was determined to be a solid-liquid two-phase paste region; when At that time, the solid fraction The solidification zone was determined to be completely solidified. Based on the solidity distribution, the spatial position of the solidification front of the billet was accurately located, providing a core basis for subsequent calculations of the billet shell thickness and surface thermal stress.

[0034] The third step is to predict the thickness distribution of the billet shell in real time at the corners and center of the surface. Based on the solidification front positioning results, the calculation is performed. At any given moment, each spatial point of the cast billet exits the crystallizer ( Effective solidification time to the current position Combined with the local convective cooling coefficient at the corresponding point , billet shell growth coefficient The solution is obtained point by point using the formula for calculating the thickness of the billet shell. The thickness of the blank shell at various points at different times The statistics are divided into corner regions and center regions, and the thickness distribution of the blank shell at the corner and the thickness distribution of the blank shell at the center are output respectively.

[0035] The fourth step is to predict the surface thermal stress distribution in real time at the corners and the center of the surface. This is based on the measured real-time surface temperature. The calculated solid fraction Combined with the elastic modulus of bearing steel at the corresponding temperature Coefficient of thermal expansion Coefficient of solidification shrinkage By using a solidification thermal stress coupling model, the solution is obtained point by point. At all times, the top point of the cast billet Surface thermal stress ; Perform regional statistics by corner area and center area, output the thermal stress distribution of the corner surface and the thermal stress distribution of the center surface respectively, and simultaneously compare the surface thermal stress safety threshold. Identify high-stress risk areas that exceed safety thresholds.

[0036] The fifth step is iterative correction and real-time output of the prediction results. The results of the billet shell thickness distribution and surface thermal stress distribution in the corner and face center regions are output to the control module in real time as the basis for calculating the target cooling water flow rate and the target deflection angle. At the same time, the real-time surface temperature of the billet collected by the infrared temperature measuring device 3 is used as a feedback correction term for the temperature field solution. The prediction results of temperature field, solidity, billet shell thickness, and thermal stress are iteratively updated step by step to form a closed-loop real-time prediction system to ensure the matching degree between the prediction results and the actual solidification state of the billet.

[0037] The solidification thermal stress coupling model uses real-time infrared temperature measurement data, real-time casting machine speed, and real-time superheat of molten steel as core inputs. The initial boundary conditions are directly correlated with the real-time superheat of the molten steel, allowing for real-time adaptation to fluctuations in the continuous casting process. This solves the problem of disconnect between traditional offline simulation models and actual on-site conditions, ensuring the real-time nature and accuracy of the prediction results. Furthermore, the solidification thermal stress coupling model uses the full-space coordinates of the billet width, thickness, and casting direction as its calculation basis. It can accurately output the solidification rate, shell thickness, and thermal stress distribution at different points in the corners and center of the billet, precisely identifying the differences in solidification states between the corners and the center of the billet, providing precise point-to-point data support for independent cooling control of the two regions.

[0038] As a specific implementation method, the formula for calculating the target cooling water flow rate in the control module is as follows: in, yes At all times, the top point of the cast billet The target cooling water flow rate corresponding to the spray nozzle. It is the baseline rated flow rate. It is the benchmark casting speed for continuous casting production. It is the benchmark superheat for continuous casting production. It is an index of the impact of pulling speed on cooling water flow rate. It is an index of the impact of superheat on cooling water flow rate. It is the cooling water flow rate correction factor for surface thermal stress deviation. It is a point on the cast billet The corresponding surface thermal stress safety threshold, It is the cooling water flow rate correction factor for the billet shell thickness. It is a point on the cast billet The corresponding blank thickness safety threshold, the surface thermal stress safety threshold and the blank shell thickness safety threshold According to the point The location is preset with corresponding values, namely the corner area and the center area. and Different preset values ​​are available.

[0039] The feedforward terms for real-time casting machine speed and real-time superheat of molten steel in the calculation formula for the target cooling water flow rate can adjust the cooling water flow rate in advance in response to changes in real-time casting machine speed and fluctuations in real-time superheat of molten steel, avoiding the lag of traditional feedback control. The feedback terms for surface thermal stress deviation and billet shell thickness deviation in the latter half can accurately correct the flow rate based on the deviation of the actual solidification state of the billet, ensuring control accuracy and balancing operating condition response speed and control stability. At the same time, it outputs differentiated target flow rates for different problems such as excessive corner thermal stress and insufficient billet shell thickness at the center, achieving differentiated control.

[0040] The formula for calculating the target cooling water deflection angle is as follows: in, yes At all times, the top point of the cast billet Corresponding to the target cooling water deflection angle of spray nozzle 4 It is the reference deflection angle. It is the coefficient of influence of pulling speed on the deflection angle of cooling water. It is the coefficient of influence of superheat on the deflection angle of cooling water. It is the cooling water deflection angle correction factor for surface thermal stress deviation. It is the cooling water deflection angle correction coefficient for the billet shell thickness deviation.

[0041] The target cooling water deflection angle formula directly correlates the real-time casting speed, real-time superheat of molten steel, real-time surface temperature of the billet, surface thermal stress deviation, and billet shell thickness deviation with the target deflection angle. By adjusting the spray angle, the landing point and coverage area of ​​the cooling water can be dynamically changed, addressing the inherent uneven heat dissipation of the billet from a spatial perspective. In corner areas, the cooling coverage can be reduced by increasing the deflection angle, while in the center area, direct, intense cooling can be achieved by decreasing the deflection angle. The target cooling water deflection angle formula shares core input parameters (real-time casting speed, real-time superheat of molten steel, thermal stress, and billet shell thickness) with the target cooling water flow rate calculation formula, achieving coordinated solution of flow rate and angle. When the flow rate is adjusted, the angle can be adapted synchronously, ensuring optimal matching of cooling intensity and coverage area, avoiding the limitations of single-variable adjustment, and significantly improving the flexibility and accuracy of cooling control.

[0042] As a specific implementation method, the control module controls the spray nozzle 4 to adjust the opening of the flow regulating valve in real time according to the real-time predicted target cooling water flow rate as follows: In the formula, This is the pipe radius corresponding to spray nozzle 4. It is the dynamic viscosity of the cooling water. This is the channel length of the corresponding spray nozzle 4. It is pi. It is the friction coefficient. This is the pipe diameter corresponding to spray nozzle 4. It is the current local resistance coefficient of the flow control valve. It is the pressure difference between the inlet and outlet of the cooling water of the spray nozzle 4. , This refers to the pressure loss that overcomes the viscous friction along the pipe wall when the cooling water flows within the 4 channels of the spray nozzle. It is the local pressure loss caused by the contraction, expansion and eddy currents of the flow channel when cooling water passes through the flow regulating valve; Based on the real-time predicted target cooling water flow rate of the spray nozzle 4 Solve for the current local resistance coefficient of the flow control valve. The local resistance coefficient of the regulating valve is adjusted according to the flow rate. Calculate the opening degree of the flow control valve. The formula is as follows: = in, It is the effective flow area of ​​the flow regulating valve at the current opening degree (when the valve opening is reduced, the flow channel will experience fluid contraction, and the actual flow area is smaller than the geometric opening area, hence it is called the effective flow area). This is the rated flow area when the flow regulating valve is fully open. yes The corresponding local resistance coefficient of the flow regulating valve; Adjust the valve opening according to the flow rate. This is used to adjust the effective flow area of ​​the flow regulating valve at its current opening. .

[0043] The flow regulating valve uses a shape memory alloy valve, and the control module changes the effective flow area by adjusting the shape memory alloy valve. This is used to adjust the opening of the flow regulating valve.

[0044] Shape memory alloys exhibit sensitive and repeatable deformation response, enabling precise matching of valve contraction and flow requirements, avoiding the lag and errors inherent in traditional valve regulation. Furthermore, shape memory alloys are heat-resistant and fatigue-resistant, allowing for long-term stable operation in the high-temperature environment of the billet cooling zone, reducing equipment maintenance frequency and costs.

[0045] Specifically, the control module drives the alloy wire to contract / reset via electric heating, causing the valve core to move axially along the guide sleeve, changing the diameter of the spray nozzle 4, and thus adjusting the opening of the flow regulating valve. The displacement sensor provides real-time feedback on the valve core position, forming a closed-loop control. The control module also controls a stepper motor to drive a rotating shaft rigidly connected to the spray nozzle 4, causing the spray nozzle 4 to deflect.

[0046] The above process, based on the Hagen-Poiseuille equation, distinguishes between pipeline friction resistance and the local resistance of flow regulating valves. It establishes a precise quantitative relationship between the target flow rate and the local resistance coefficient, effective flow area, and valve opening of the flow regulating valve, ensuring accurate execution of the target flow rate. The correlation logic between the effective flow area and valve opening in the formula perfectly matches the deformation control characteristics of shape memory alloy valves. By precisely controlling the contraction of the flow regulating valve to change the effective flow area, millisecond-level precise flow rate adjustment can be achieved.

[0047] As a specific implementation method, the control module controls the spray nozzle 4 to adjust the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle as follows: In the formula, yes At all times, the top point of the cast billet The mechanical deflection angle corresponding to spray nozzle 4; The target cooling water deflection angle of the spray nozzle 4 is predicted in real time. Solve for the mechanical deflection angle of the spray nozzle 4. This is to adjust the mechanical deflection angle of the spray nozzle 4.

[0048] The above process considers the influence of the cross-sectional area of ​​the spray nozzle 4 (flow regulating valve opening) on ​​the actual deflection angle of the cooling water, solving the problem of inconsistency between the mechanical deflection angle and the actual jet angle. This ensures the accuracy of the cooling water landing point and coverage area, avoiding cooling blind spots or over-cooling. The effective flow area mentioned in the formula... By directly linking the flow regulating valve opening, the flow regulation opening parameter is deeply bound to the mechanical deflection parameter of the angle regulation. When the flow regulating valve opening changes and causes the jet characteristics to change, the mechanical deflection angle can be adjusted synchronously to ensure the stable execution of the target deflection angle. This achieves coordinated adaptation of the two control dimensions of flow and angle, avoiding mutual interference between the two variables.

[0049] like Figure 2 As shown, The deflection angle of the cooling water for the corresponding spray nozzle 4 in the corner region or the corresponding spray nozzle 4 in the center region. This refers to the mechanical deflection angle of the corresponding spray nozzle 4 in the corner region or the corresponding spray nozzle 4 in the center region. The cross-sectional area of ​​the corresponding spray nozzle 4 in the corner region or the corresponding spray nozzle 4 in the center region.

[0050] The control module controls the degree of axial offset of the spray nozzle 4. This is the actual degree of axial offset of the cooling water. When the shape memory alloy valve changes its effective flow area... Increase, Same Down, Larger; when shape memory alloy valves change the effective flow area Decrease, Same Down, Smaller.

[0051] In the initial stage of startup of the system for controlling the surface quality of bearing steel produced from small-section cast billets, the local convection cooling coefficient of this invention is... Actual cooling water flow rate in the calculation formula and actual cooling water spray angle The reference rated flow rate is calibrated offline. Reference deflection angle As initial empirical values; after entering stable operation, the control module calculates the target cooling water flow rate in real time based on the real-time surface temperature of the corner and face center regions of the billet, the real-time casting speed of the casting machine, the real-time superheat of the molten steel, and the billet shell thickness distribution and surface thermal stress distribution predicted by the solidification thermal stress coupling model. and the deflection angle of the target cooling water The execution order is then issued; after the actuator moves, the actual cooling water flow rate of the spray nozzle 4 is collected in real time by the flow sensor and angle encoder. and actual cooling water spray angle And substitute this actual executed value as the sole input. The formula calculates the local convection cooling coefficient; the calculated coefficient is... The results are then used to update the billet thickness and surface thermal stress prediction, thereby correcting the target flow rate and target angle for the next moment, forming a complete real-time closed-loop control.

[0052] The physical parameters involved in the above formulas are further explained as follows: Billet shell growth coefficient , is a coefficient characterizing the shell growth rate of bearing steel billets in the secondary cooling zone of continuous casting. It comprehensively reflects the influence of the thermal properties of bearing steel and cooling conditions on the shell thickness growth. The calibration method is as follows: the thermal property parameters in different temperature ranges are measured by a high-temperature laser thermal conductivity meter, and the initial reference value is calculated by combining it with unsteady solidification heat transfer numerical simulation. Then, the actual thickness of the billet shell under different casting speeds and cooling intensities is measured by nail shooting tests on the continuous casting site, and the final calibration value adapted to the on-site working conditions is obtained by back-calculation and fitting.

[0053] The Influence of Pulling Speed ​​on Cooling Water Flow Rate The index characterizes the impact of continuous casting machine speed fluctuations on the cooling water flow demand in the secondary cooling zone and serves as an index for feedforward control of secondary cooling water distribution. The calibration method involves conducting stable billet casting tests at different speed gradients on-site, using the uniformity of billet surface temperature and the absence of surface cracks as control objectives, and gradually refining the values ​​to obtain the final calibration value.

[0054] It is an index representing the influence of superheat on cooling water flow rate, characterizing the degree of impact of superheat fluctuations in molten steel in the tundish on the cooling water flow rate demand in the secondary cooling zone. The calibration method is as follows: continuous casting tests with different superheat gradients are carried out, with the control target being a central porosity rating ≤1.0 and no central cracks, and the final calibration value is obtained by gradually correcting the results.

[0055] Influence coefficient of pulling speed on cooling water deflection angle This characterizes the influence of continuous casting machine speed fluctuations on the deflection angle of the target cooling water in the spray nozzle. The calibration method is as follows: conduct billet pulling tests with different speed gradients, using the surface temperature difference between the corner and the center of the face ≤ a preset temperature difference value (e.g., 50℃) and the absence of transverse cracks at the corner as control targets, and gradually correct to obtain the final calibration value.

[0056] Influence coefficient of superheat on cooling water deflection angle This characterizes the influence of tundish superheat fluctuations on the deflection angle of the target cooling water in the spray nozzles. The calibration method is as follows: continuous casting tests with different superheat gradients are conducted, with the control targets being a face-centered region ≥ the preset value of equiaxed crystal ratio (e.g., 30%) and a central porosity ≤ 1.0 grade. The final calibration value is obtained by gradually correcting the values.

[0057] Cooling water deflection angle correction factor for surface thermal stress deviation This characterizes the deviation between the surface thermal stress of the billet and the safety threshold, and corrects the deflection angle of the target cooling water in the spray nozzle. It is used to suppress cracking defects caused by excessive corner thermal stress. The calibration method is as follows: taking the corner surface thermal stress of the billet ≤ the preset value of the corner surface thermal stress (e.g., 22 MPa) and the absence of transverse corner cracks as the control targets, the final calibration value is obtained through closed-loop iteration of infrared thermometry and stress prediction results.

[0058] Cooling water deflection angle correction factor for billet thickness deviation This characterizes the deviation between the actual billet shell thickness and the safety threshold, and corrects the deflection angle of the target cooling water in the spray nozzle. It is used to address the risks of steel leakage and bulging caused by insufficient thickness of the center billet shell. The calibration method is as follows: the billet shell thickness is measured through a nail gun test. The control targets are: the difference between the thickness of the corner and the center billet shell ≤ the preset value of the difference between the thickness of the corner and the center billet shell (e.g., 2mm), and the thickness of the center billet shell ≥ the preset value of the center billet shell thickness (e.g., 8mm). The final calibration value is obtained by gradually correcting the values.

[0059] Friction coefficient The Reynolds number (R0) is a parameter characterizing the resistance of cooling water to viscous friction along the pipe wall as it flows through the spray nozzle pipe. It is used to calculate the valve opening corresponding to the target flow rate. The calibration method is as follows: First, calculate the Reynolds number (a dimensionless number in fluid mechanics used to measure the ratio of inertial force to viscous force in a fluid) based on the pipe diameter, cooling water flow rate, and dynamic viscosity of the cooling water. Then, iterate the Reynolds number using the Kohlbrook formula to obtain its final value.

[0060] Heat transfer correction factor This coefficient characterizes the convective heat transfer efficiency correction between the sprayed cooling water and the high-temperature billet surface, comprehensively correcting for the influence of nozzle atomization characteristics, cooling water temperature, billet surface oxide scale, and steam film effect on the actual heat transfer intensity. The calibration method involves conducting spray heat transfer tests on a secondary cooling nozzle test bench, measuring the heat transfer coefficient of the billet sample under different flow rates and spray angles, fitting the baseline value of the heat transfer correction coefficient, and combining the measured data of the billet surface temperature on-site with numerical simulation results to correct for the heat transfer efficiency deviation caused by the steam film effect and iron oxide scale, thus obtaining the final calibration value.

[0061] Cooling water flow rate index The flow rate index characterizes the influence of spray cooling water flow rate on the convective cooling coefficient of the billet surface, reflecting the nonlinear influence of flow rate changes on heat transfer intensity. The calibration method involves conducting spray heat transfer tests with different flow rate gradients on a nozzle test bench, measuring the convective cooling coefficient at the corresponding flow rate, and obtaining the calibration value of the flow rate index through power function fitting.

[0062] Mechanical deflection angle index This calibrates the influence of the mechanical deflection angle of the spray nozzle on the convective cooling coefficient of the cast billet surface, reflecting the attenuation of heat transfer intensity when the spray angle deviates from vertical. The calibration method is as follows: spray heat transfer tests with different deflection angle gradients are conducted on a nozzle test bench, the convective cooling coefficient at the corresponding angle is measured, and the calibration value of the deflection angle exponent is obtained by power function fitting.

[0063] Cooling water jet diffusion coefficient The parameter characterizes the radial diffusion and expansion characteristics of the sprayed cooling water jet after it exits the nozzle, reflecting the coverage area and energy density distribution of the jet. The calibration method involves conducting jet morphology tests on a nozzle test bench, measuring the jet diffusion radius at different spray distances using the filter paper method and high-speed photography, fitting a baseline value for the jet diffusion coefficient, and combining this with measured data of the surface temperature distribution of the cast billet to correct for the jet attenuation characteristics under high-temperature conditions, thus obtaining the final calibration value.

[0064] Solid fraction-temperature function corresponding to the equilibrium phase diagram of bearing steel It is a function that establishes a one-to-one correspondence between the solid fraction and the instantaneous temperature of the billet based on the equilibrium phase diagram of bearing steel and the lever law. It characterizes the change law of solid mass fraction with temperature in the solid-liquid two-phase region during solidification and is the basic function in the solidification thermal stress coupling model.

[0065] To better illustrate the beneficial effects of the technical solution of this invention, experiments were conducted on 150mm×150mm small cross-section square billets using GCr15 high-carbon chromium bearing steel. Production was carried out using a four-strand, four-crystal arc-shaped continuous casting machine with an effective crystallizer length of 900mm. The secondary cooling zone was divided into four cooling sections, and the test area was sections 1-3 of the secondary cooling zone. The cooling water supply pressure in the secondary cooling zone was constant at 0.6MPa, and the cooling water temperature was 25℃. Reference casting speed... =2.2m / min, with a test speed fluctuation range of 2.0~2.4m / min; reference superheat .

[0066] Offline pre-calibration parameters: Calibration reference rated flow rate =120 L / min, reference deflection angle =5°, safety threshold for surface thermal stress in corner areas =22MPa, safety threshold for billet shell thickness in corner region =12mm, surface thermal stress safety threshold in the face-centered region =45MPa, safety threshold for billet shell thickness in the face center region =8mm.

[0067] (1) The infrared temperature measuring device collects the real-time surface temperature of the corner and center area of ​​the billet. Synchronously collect real-time casting speed data of the casting machine Real-time superheat of molten steel (2) The control module adopts the solidification thermal stress coupling model of the present invention to calculate the solid fraction distribution, shell thickness distribution and surface thermal stress distribution of the corner and face center regions of the billet step by step; (3) Based on the prediction results, combined with the real-time casting speed and the real-time superheat of the molten steel, the target cooling water flow rate and target deflection angle of the spray nozzles in the corner and face center regions are solved independently using the target flow rate and target deflection angle formulas of the present invention: when the surface thermal stress in the corner region exceeds the safety threshold, the spray nozzle flow rate is automatically reduced and the mechanical deflection angle is increased to reduce the corner cooling. Strength; When the thickness of the billet shell in the center area is lower than the safety threshold, the spray nozzle flow rate is automatically increased and the mechanical deflection angle is reduced to enhance the direct cooling of the center area; (4) The control module calculates the target opening degree of the shape memory alloy valve according to the target flow rate, calculates the target rotation angle of the stepper motor according to the target deflection angle and issues the execution command; At the same time, the actual cooling water flow rate and actual spray angle of the spray nozzle 4 are collected in real time through the flow sensor and angle encoder, and substituted into the local convection cooling coefficient formula to correct the prediction results of the solidification thermal stress coupling model in real time, forming a closed-loop control of the whole process. The test batch continuously and stably produced 10 furnaces, and randomly selected 100 billets for full-item quality inspection, and recorded the process and quality data.

[0068] A proportional control scheme is set up: The mainstream PID (Proportional-Integral-Derivative) dynamic secondary cooling water distribution scheme based on surface temperature feedback in the existing steel industry is adopted. All other basic process conditions are completely consistent with the example. The specific implementation process is as follows: Secondary cooling sections 1-3 use conventional fixed-angle atomizing spray nozzles. The nozzle installation angle is uniformly 0° direct spray, without mechanical deflection adjustment function. Each cooling section is equipped with only one set of total flow pneumatic regulating valves, uniformly controlling the total cooling water flow for each cooling section, without independent control for corners or the center of the surface. Each section is equipped with only one infrared temperature measuring device to collect the average temperature of the center of the billet's wide face, without corner or center of the surface temperature measurement function. A traditional PID dynamic water distribution model is adopted, using the average temperature of the center of the billet's wide face as the feedback variable and the real-time casting speed as the feedforward variable. The total cooling water flow of each cooling section is dynamically adjusted according to a preset fixed secondary cooling water distribution table. There is no solidification thermal stress coupling model prediction link, no closed-loop correction logic for billet shell thickness and surface thermal stress, and no spray angle adjustment function. The test batch and the example were made of the same heat number and the same pouring of molten steel. Ten heats were produced continuously and stably. One hundred billets were randomly selected and tested using the same testing methods and standards as in this example to complete all quality tests.

[0069] Table 1 Comparison of Quality Inspection Results The quality inspection results are shown in Table 1. The technical solution of this invention is superior to the comparative PID dynamic secondary cooling water distribution scheme in terms of surface cracks and central porosity. Specifically, the surface quality of the cast billet is assessed using a combination of visual inspection and magnetic particle testing. Low-magnification microstructure inspection is performed according to GB / T226-2015 "Acid Etching Inspection Method for Low-Magnification Microstructure and Defects of Steel"; central porosity is assessed according to GB / T1979-2001 "Rating Chart of Low-Magnification Microstructure Defects of Structural Steel".

[0070] The present invention solves the problem of "corner overcooling and cracking and center undercooling and porosity" in small cross-section bearing steel billets by differential control of corner and center sections, combined with the coordinated adjustment of flow rate and angle. The surface cracks and internal density of the billet are significantly improved, meeting the quality requirements of high-end bearing steel.

[0071] This invention utilizes a predictive control based on a solidification thermal stress coupling model. Compared to existing reactive feedback control technologies, it significantly improves adaptability to fluctuations in operating conditions, avoiding quality instability caused by fluctuations in real-time casting speed and molten steel superheat. This results in a significant improvement in production stability and yield. Traditional dynamic water distribution methods (such as PID dynamic secondary cooling water distribution schemes) only initiate adjustments after the billet surface temperature deviates from the target value, exhibiting significant lag. When casting speed fluctuates or molten steel superheat changes, the cooling intensity cannot match the actual solidification state of the billet in time, easily causing instantaneous overcooling cracking at the corners or insufficient instantaneous cooling at the center, leading to large fluctuations in billet quality and low yield. This invention, by real-time acquisition of billet surface temperature, real-time casting speed, and real-time molten steel superheat, predicts the billet shell thickness and surface thermal stress distribution at the next moment. Before temperature deviation, stress exceedance, or billet shell unevenness occur, the corresponding target cooling water flow rate and spray angle are calculated, and the spray nozzles are driven to adjust in advance, achieving proactive control with feedforward pre-adjustment and feedback fine-tuning. When the casting speed increases, the system can increase the cooling intensity in advance to avoid insufficient billet shell growth; when the real-time superheat of the molten steel increases, the system can strengthen the cooling of the center region in advance to prevent central porosity and segregation; when stress concentration is about to occur at the corners, the system can reduce the flow rate and increase the spray angle in advance to avoid overcooling at the corners. Therefore, this invention can quickly, smoothly, and without lag adapt to various working conditions such as real-time casting speed fluctuations, real-time superheat changes of molten steel, and cooling environment disturbances, always keeping thermal stress and billet shell thickness within safe thresholds. This fundamentally eliminates quality defects such as surface cracks, internal porosity, and uneven structure caused by working condition fluctuations, making the continuous casting production process more stable, billet consistency higher, and overall pass rate significantly improved.

[0072] Example 2 A method for controlling the surface quality of bearing steel produced from small-section cast billets includes: Based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, a solidification thermal stress coupling model is used to predict the billet shell thickness distribution and surface thermal stress distribution in the corner and center regions in real time. Based on the billet shell thickness distribution and the surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles 4 in the corner and center regions of the billet are predicted in real time. The spray nozzles 4 are controlled to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

[0073] Example 3 A computer program product includes a computer program / instructions that, when executed by a processor, implement the calculation process of the control module in the method for controlling the surface quality of bearing steel produced from small-section cast billets in Embodiment 2.

[0074] The contents not described in detail in this specification are prior art known to those skilled in the art. Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0076] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0077] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0078] 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 its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A system for controlling the surface quality of bearing steel produced from small-section cast billets, characterized in that, include: The spray nozzle, infrared temperature measuring device, and control module are included. The opening degree of the flow regulating valve and the mechanical deflection angle of the spray nozzle can be adjusted. The infrared temperature measuring device is used to measure the real-time surface temperature of the corner area and the center area of ​​the billet. Multiple spray nozzles form an array, with some spray nozzles used to cool the corner areas of the billet and others used to cool the center area of ​​the billet. The control module is used to predict the thickness distribution and surface thermal stress distribution of the billet shell in the corner and center regions in real time based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, using a solidification thermal stress coupling model. Based on the thickness distribution and surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, the module predicts the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles in the corner and center regions of the billet in real time. The module controls the spray nozzles to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

2. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 1, characterized in that, In the control module, based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, a solidification thermal stress coupling model is used to predict the billet shell thickness distribution and surface thermal stress distribution in the corner and center regions in real time. The specific method is as follows: The formula for the solidification thermal stress coupling model is as follows: Define the convection term as Define the initial boundary conditions as follows ; in, It is the Hamiltonian operator. It is the density of bearing steel at the corresponding temperature. This is the specific heat capacity of bearing steel at a corresponding temperature. It is the thermal conductivity of bearing steel at the corresponding temperature. It is the latent heat of solidification of bearing steel. It is the liquidus temperature of bearing steel. It is the real-time casting speed. These are the spatial coordinates of the billet width direction, thickness direction, and billet pulling direction, respectively. It is a time-varying variable. yes At all times, the top point of the cast billet Real-time surface temperature of the billet, point Real-time surface temperature based on point The location includes the real-time surface temperature of the corner area and the center area. It is the initial real-time surface temperature of the billet when it enters the secondary cooling zone. It refers to the real-time superheat of molten steel. yes At all times, the top point of the cast billet solid fraction, Specifically as follows: in, It is the solidus temperature of bearing steel. It is the solid fraction-temperature function corresponding to the equilibrium phase diagram of bearing steel; Real-time surface temperature of the corner and center areas of the cast billet Real-time casting speed Input the convection term, and the real-time superheat of the molten steel. Solve for the initial boundary conditions of the input variables At all times, the top point of the cast billet solid fraction ; in, yes At all times, the top point of the cast billet Surface thermal stress, It is the elastic modulus of bearing steel at the corresponding temperature. It is the coefficient of thermal expansion of bearing steel at the corresponding temperature. It is the solidification shrinkage coefficient of bearing steel at the corresponding temperature; in, yes At all times, the top point of the cast billet The thickness of the blank shell, It is the growth coefficient of the billet shell. yes At all times, the top point of the cast billet from The time taken to move to the current position. Real-time casting speed Decide, yes At all times, the top point of the cast billet The local convective cooling coefficient.

3. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 2, characterized in that, The formula for calculating the target cooling water flow rate in the control module is as follows: in, yes At all times, the top point of the cast billet The target cooling water flow rate corresponding to the spray nozzle. It is the baseline rated flow rate. It is the benchmark casting speed for continuous casting production. It is the benchmark superheat for continuous casting production. It is an index of the impact of pulling speed on cooling water flow rate. It is an index of the impact of superheat on cooling water flow rate. It is the cooling water flow rate correction factor for surface thermal stress deviation. It is a point on the cast billet The corresponding surface thermal stress safety threshold, It is the cooling water flow rate correction factor for the billet shell thickness. It is a point on the cast billet The corresponding blank thickness safety threshold, the surface thermal stress safety threshold and the blank shell thickness safety threshold According to the point The location has a preset value.

4. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 2, characterized in that, The formula for calculating the target cooling water deflection angle in the control module is as follows: in, yes At all times, the top point of the cast billet The target cooling water deflection angle corresponding to the spray nozzle. It is the reference deflection angle. It is the coefficient of influence of pulling speed on the deflection angle of cooling water. It is the coefficient of influence of superheat on the deflection angle of cooling water. It is the cooling water deflection angle correction factor for surface thermal stress deviation. It is the cooling water deflection angle correction coefficient for the billet shell thickness deviation.

5. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 3, characterized in that, The specific method for controlling the spray nozzles to adjust the opening of the flow regulating valve in real time according to the real-time predicted target cooling water flow rate in the control module is as follows: In the formula, This is the pipe radius of the corresponding spray nozzle. It is the dynamic viscosity of the cooling water. This is the channel length of the corresponding spray nozzle. It is pi. It is the friction coefficient. This refers to the pipe diameter of the corresponding spray nozzle. It is the current local resistance coefficient of the flow control valve. It is the pressure difference between the inlet and outlet of the cooling water in the spray nozzle. , It is the pressure loss that overcomes the viscous friction along the pipe wall when the cooling water flows in the spray nozzle channel. It is the local pressure loss caused by the contraction, expansion and eddy currents of the flow channel when cooling water passes through the flow regulating valve; Based on the real-time predicted target cooling water flow rate of the spray nozzle Solve for the current local resistance coefficient of the flow control valve. The local resistance coefficient of the regulating valve is adjusted according to the flow rate. Calculate the opening degree of the flow control valve. The formula is as follows: = in, It is the effective flow area of ​​the flow regulating valve at its current opening degree. This is the rated flow area when the flow regulating valve is fully open. yes The corresponding local resistance coefficient of the flow regulating valve; Adjust the valve opening according to the flow rate. This is used to adjust the effective flow area of ​​the flow regulating valve at its current opening. .

6. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 4, characterized in that, The specific method for controlling the spray nozzles to adjust the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle in the control module is as follows: In the formula, yes At all times, the top point of the cast billet The mechanical deflection angle corresponding to the spray nozzle; The target cooling water deflection angle of the spray nozzle is predicted in real time. Solve for the mechanical deflection angle of the spray nozzle. This is to adjust the mechanical deflection angle of the spray nozzle.

7. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 2, characterized in that, The At all times, the top point of the cast billet Local convection cooling coefficient The calculation formula is as follows: in, It is the heat transfer correction factor. yes At all times, the top point of the cast billet Corresponding to the actual cooling water flow rate of the spray nozzle, It is the cooling water flow rate index. It is the mechanical deflection angle index. yes At all times, the top point of the cast billet The corresponding actual cooling water spray angle yes At all times, the top point of the cast billet The vertical distance from the nozzle outlet to the surface of the cast billet. The diffusion coefficient of the cooling water jet is denoted as .

8. The system for controlling the surface quality of bearing steel produced from small-section cast billets according to claim 5, characterized in that, The flow regulating valve is a shape memory alloy valve, and the control module changes the effective flow area by adjusting the shape memory alloy valve. This is used to adjust the opening of the flow regulating valve.

9. A method for controlling the surface quality of bearing steel produced from small-section cast billets, characterized in that, include: Based on the real-time surface temperature of the corner and center regions of the billet, combined with the real-time casting speed and the real-time superheat of the molten steel, a solidification thermal stress coupling model is used to predict the billet shell thickness distribution and surface thermal stress distribution in the corner and center regions in real time. Based on the billet shell thickness distribution and the surface thermal stress distribution, and again combined with the real-time casting speed and the real-time superheat of the molten steel, the target cooling water deflection angle and target cooling water flow rate of the corresponding spray nozzles in the corner and center regions of the billet are predicted in real time. The spray nozzles are controlled to adjust the opening of the flow regulating valve and the mechanical deflection angle in real time according to the real-time predicted target cooling water deflection angle and target cooling water flow rate, so as to spray cooling water onto the billet.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the calculation process of the method for controlling the surface quality of bearing steel produced by small-section casting billets as described in claim 9.

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