A method for experimentally determining the optimum water ratio for thickness-direction uniform cooling after hot plate rolling

Abstract

An experimental method for determining the optimal water ratio for uniform cooling of hot-rolled steel plates in the thickness direction involves a circular track combined with a trolley. The trolley carries the sample in a circular motion via a sample support platform. The circular track is an elliptical track comprising two parallel straight sections and two semicircular sections. At least one cooling spray box is set along the straight sections of the track to achieve an infinitely long cooling zone at any workpiece speed. The cooling zone is designed according to the layout of the cooling zone after rolling on the production line. For a sample of a certain steel grade and thickness, the flow rate corresponding to the starting and stopping temperatures and the optimal cooling rate determined by the cooling experiment is adjusted within a certain range of the flow rate values ​​of the upper and lower spray boxes to conduct the cooling experiment. By measuring the cooling curves of the upper and lower surfaces of the sample, the optimal upper and lower water ratio that satisfies the uniform cooling of the steel plate in the thickness direction is determined based on the fitting degree of the upper and lower surface cooling curves, thereby achieving the goal of simultaneously meeting the requirements of plate shape and performance after cooling.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to an experimental method for determining the optimal water ratio for uniform cooling of hot-rolled plates in the thickness direction. Background Technology

[0002] The thick-axis uniform cooling technology for hot-rolled steel plates refers to achieving uniform cooling in the thickness direction by controlling the water ratio between the upper and lower cooling spray boxes (hereinafter referred to as water ratio), thereby optimizing the shape of the hot-rolled steel plate after cooling. Currently, there are no corresponding experimental measurement methods, and it is often necessary to conduct tests during on-site production. However, there are many factors that affect the shape of the plate on-site, and temperature measurement during the cooling process is basically impossible, making it difficult to assess the uniformity of thick-axis cooling.

[0003] In summary, there is currently no experimental method, either domestically or internationally, for determining the optimal water ratio for uniform cooling of hot-rolled plates in the thickness direction after rolling, based on methods and devices for achieving an infinitely long cooling zone at arbitrary workpiece speeds. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental method for determining the optimal water ratio for uniform cooling of hot-rolled steel plates in the thickness direction. By employing a circular track combined with a trolley, an infinitely long cooling zone is achieved at any workpiece speed. The cooling zone is designed according to the layout of the cooling zone after rolling on the production line. For a sample of a specific steel grade and thickness, the flow rate corresponding to the starting and stopping temperatures and the optimal cooling rate determined in the cooling experiment is adjusted within a certain range of these flow rates. By measuring the cooling curves of the upper and lower surfaces of the sample, the optimal upper and lower water ratio for uniform cooling of the steel plate in the thickness direction is determined based on a fitting degree of over 80%, achieving the goal of simultaneously meeting the requirements for plate shape and performance after cooling. Furthermore, since the determination method described in this invention is implemented under conditions essentially consistent with the actual operating conditions of the production line, product design output and production line process control are more accurate and efficient, effectively accelerating product development, improving process control accuracy and stability, and reducing production line trial production costs.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An experimental method for determining the optimal water ratio for uniform cooling along the thickness of a hot-rolled plate includes the following steps:

[0007] 1) A circular track combined with a trolley is used. The trolley carries the sample on the sample support platform and moves in a circular motion. The circular track is an elliptical track consisting of two parallel straight sections and two semicircular sections. At least one cooling spray box is set along the straight sections of the track to cool the upper and / or lower surfaces of the sample. Each cooling spray box includes upper and lower cooling spray boxes. Preferably, the trolley is driven by a motor or by a traction drive.

[0008] 2) The sample is heated offline or online, and the temperature of the sample is measured by a temperature measuring device installed on the trolley. After the sample reaches the temperature required by the process, the trolley is driven to move along the track, carrying the sample through the cooling spray box in sequence. The trolley carries the heated sample in a circular motion at a constant speed or with a certain acceleration, as specified in the process speed. The sample support platform has a hollow center, and after the sample is fixed to the support platform, the upper and lower surfaces of the sample are unobstructed. As the sample passes through the cooling spray box, the jets emitted from the cooling spray box directly spray onto the sample, simultaneously cooling the upper and lower surfaces of the sample. During this process, the sample is driven through a theoretically infinitely long cooling zone at a set speed, ensuring that the sample is cooled from the initial cooling temperature to the set target temperature under conditions consistent with the production line operating conditions. The sample temperature and cooling rate are monitored and obtained in real time.

[0009] Sample running speed: 0–25 m / s, acceleration: 0–0.5 m / s² 2 ;

[0010] The flow rate adjustment range for each cooling spray box is 0–300 m³ / h. 3 / h, preferably 10-50m 3 Cooling experiments were conducted by setting the flow rate intervals to increase or decrease at intervals of / h;

[0011] The cooling temperature is 700-1000℃. Preferably, the cooling experiment is conducted by setting the temperature increments or decreases of 40-60℃.

[0012] The cooling temperature ranges from room temperature to 800℃. Preferably, the experiment is conducted by setting the temperature increments or decreases of 30℃ to 50℃.

[0013] If there are more than two cooling spray boxes, the spacing between the cooling spray boxes should be consistent with the production line design.

[0014] 3) Perform performance and microstructure tests on the samples;

[0015] 4) Repeat steps 3) and 4) and select cooling control parameters that meet the requirements of performance and organization based on the measured data, including determining the flow rate value, start-up cooling temperature and final cooling temperature corresponding to the optimal cooling rate.

[0016] 5) Adjust the flow rates of the upper and lower spray boxes within a certain range of the flow rate value corresponding to the optimal cooling rate. The adjustment range of the flow rates of the upper and lower spray boxes is 50% to 150% of the measured flow rate value. Preferably, the adjustment range of the flow rate of the upper spray box is 50% to 100% of the measured flow rate value, and the adjustment range of the flow rate of the lower spray box is 100% to 150% of the measured flow rate value.

[0017] Cooling experiments were conducted at different water-to-water ratios according to the production line process speed and the determined start-up and final cooling temperatures. The temperature curves of the upper and lower surfaces of the sample were measured. Based on the fact that the fitting degree of the cooling curves of the upper and lower surfaces of the sample is above 80%, the optimal water-to-water ratio that satisfies the uniform cooling of the steel plate in the thickness direction was determined. The designed water-to-water ratio is 3:1 to 1:3; preferably, the water-to-water ratio is 1:1 to 1:2.

[0018] Preferably, in step 2), the cooling rate CR of the steel plate is calculated based on the starting cooling temperature T1, the stopping cooling temperature T2, and the cumulative cooling time t recorded during the experiment. The cumulative cooling time t is in seconds, and the cooling rate ranges from 0 to 1000℃ / s.

[0019] Preferably, in step 3), the performance Xact of the steel plate is measured by a testing device. Xact is considered qualified if it is within the allowable positive and negative tolerance range of the target performance Xtar, i.e., ΔX1≤(Xact-Xtar)≤ΔX2, where ΔX1: negative tolerance, ΔX2: positive tolerance. The target performance and the range of positive and negative tolerances of the steel plate are determined by the user's requirements.

[0020] Preferably, in step 4), the experimental results under different combinations of cooling rate, start-up cooling temperature and stop-down cooling temperature are statistically analyzed, and the combination that meets the product performance is selected for comprehensive comparison. Based on the production line layout and process system, the optimal cooling rate, start-up cooling temperature and stop-down cooling temperature that meet the maximum process window of product production are determined; the preferred start-up cooling temperature is 800~950℃, and the preferred stop-down cooling temperature is 550℃~750℃.

[0021] Preferably, the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable, with the nozzle diameter of the cooling spray box being 3 to 30 mm and the distance between the cooling spray box and the sample surface being 50 to 2200 mm.

[0022] Preferably, the spacing between the cooling spray boxes is 0–1.5 m, and the flow rate of the cooling spray boxes is 0–300 m³ / h. 3 / h, the number of nozzles in the cooling spray box is 1 to 200; the length of the cooling spray box is 100 to 6000 mm.

[0023] Preferably, the circular motion speed of the sample, i.e., linear velocity or angular velocity, is monitored in real time, and the velocity of the sample can be changed online according to the measured temperature data based on the predetermined cooling process, i.e., increasing speed, decreasing speed, or maintaining a constant speed.

[0024] Preferably, the sample is heated offline or online. Preferably, the offline heating method involves heating the sample to the required process temperature, then fixing it on the sample support platform. When the sample approaches the predetermined cooling temperature, the trolley is driven to move along the circular track, carrying the sample through the cooling spray box, i.e., through a theoretically infinitely long cooling zone, to complete the cooling or heat treatment process. The online heating method involves fixing the sample on the sample support platform first, then heating it. When the required process temperature is reached, the heating device is removed from the circular track area, and then the trolley is driven to move along the circular track to complete the cooling or heat treatment process.

[0025] Preferably, the heating is performed using resistance heating, that is, the sample is held on both sides by electrodes and heated directly online by a large current; or, induction heating is performed.

[0026] Preferably, water cooling or air cooling is used to cool the sample.

[0027] In the experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling described in this invention:

[0028] The experimental setup consists of a circular track formed by two parallel straight segments and two semi-circular arc segments. A trolley carrying the sample is placed on the track, and the trolley moves the sample along the circular track.

[0029] The trolley moves the sample to achieve the specified process speed, which can be maintained at a constant speed or accelerated at a certain speed.

[0030] Cooling spray boxes are arranged in an array on two straight segments to form two straight cooling zones, which can simultaneously cool both the upper and lower surfaces.

[0031] The hot sample can be driven to any specified speed (low speed, medium speed or high speed) and pass through a theoretically infinitely long cooling zone while in motion, so as to ensure that the sample is cooled from the starting temperature to the target temperature under conditions that are basically consistent with the working conditions on the production line.

[0032] 1) The water cooling process is completed in a straight section, which improves the consistency between the experimental and production line conditions;

[0033] 2) The sample speed is adjustable and controllable over a wide range, with a sample speed range of 0–25 m / s and an acceleration range of 0–0.5 m / s². 2 ;

[0034] 3) Infinite cooling capacity, capable of meeting cooling needs within any temperature range, sample temperature range: room temperature to 1000℃;

[0035] 4) Real-time temperature monitoring during the cooling process, precise control of the start-up and stop-cooling temperatures, sample temperature range: room temperature to 1000℃;

[0036] 5) The cooling process time is accumulated in real time, and the cooling stop time is precisely controlled to meet the control requirements of phase change time. The range of cooling time and cooling stop time is 0 to infinite.

[0037] The distance between the cooling spray box and the sample surface, as well as the nozzle diameter, are adjustable. The basic principle is that the flow rate of cooling water to the sample surface should be kept as consistent as possible with the production line design.

[0038] The spacing, flow rate, and number of nozzles of the cooling spray box are adjustable. The basic principle is that the flow rate density of cooling water to the sample surface should be kept as consistent as possible with the production line design.

[0039] The distance between the cooling spray box and the sample surface, as well as the nozzle diameter, are adjustable. The basic principle is that the flow rate of cooling water to the sample surface should be kept as consistent as possible with the production line design, because the water cooling heat exchange capacity is closely related to the water flow rate on the sample surface. This ensures that, while maintaining consistency with the production line cooling process, the experimental cooling rate is consistent with the field conditions. The nozzle diameter of the cooling spray box ranges from 3 to 30 mm, and the distance between the cooling spray box and the sample surface ranges from 50 to 2200 mm.

[0040] The spacing, flow rate, and number of nozzles in the cooling spray boxes are adjustable. The basic principle is to ensure that the flow rate density of the cooling water to the sample surface is as consistent as possible with the production line design. This is a crucial technical point for simulating the actual operating conditions of the production line, as the water cooling heat exchange capacity is closely related to the flow rate density of water on the sample surface. This ensures that, while maintaining consistency with the production line cooling process, the experimental cooling rate is consistent with the actual operating conditions. The spacing between the cooling spray boxes ranges from 0 to 1.5 meters, and the flow rate ranges from 0 to 300 cubic meters per second. 3 / h, the number of nozzles in the cooling spray box ranges from 0 to 200.

[0041] If the height and spacing of the cooling spray boxes are the same as the production line, the flow rate can be simply calculated based on the length ratio of the cooling spray boxes. If the maximum flow rate of the spray boxes in different cooling zones of the production line is different, the flow rate of the spray boxes in the cooling zone with the maximum flow rate should be used to calculate the flow rate of the experimental device's spray boxes. The length range of the cooling spray boxes is 100–6000 mm.

[0042] Experimental determination of the optimal water ratio for uniform cooling in the thickness direction:

[0043] Based on the determined flow rate corresponding to the optimal cooling rate, the flow rates of the upper and lower spray boxes are adjusted within a certain range of this flow rate. Cooling experiments are conducted at different water ratios according to the production line process speed and the determined start-up and final cooling temperatures. The temperature curves of the upper and lower surfaces of the sample are measured. Based on the fitting degree of the upper and lower surface cooling curves of more than 80%, the optimal upper and lower water ratio that satisfies the uniform cooling of the steel plate thickness is determined.

[0044] The present invention selects the water ratio as the process parameter for uniform cooling of products, mainly so that it can be applied to production lines with different post-rolling cooling configurations.

[0045] The beneficial effects of this invention are:

[0046] This invention utilizes a circular track combined with a trolley to achieve an infinitely long cooling zone at any workpiece speed. The cooling zone is designed according to the layout of the post-rolling cooling zone on the production line. For a sample of a specific steel grade and thickness, the flow rate corresponding to the starting and stopping temperatures and the optimal cooling rate determined by the cooling experiment is adjusted within a certain range to conduct the cooling experiment. By measuring the cooling curves of the upper and lower surfaces of the sample, and based on a fitting degree of over 80% for the upper and lower surface cooling curves, the optimal upper and lower water ratio is determined to ensure uniform cooling of the steel plate along its thickness, thus simultaneously meeting the requirements for plate shape and performance after cooling.

[0047] Furthermore, since the experimental measurement method described in this invention is implemented under conditions that are basically consistent with the actual working conditions of the production line, the product design output and production line process control are more accurate and efficient, which can effectively accelerate the product development speed, improve the accuracy and stability of process control, and reduce the production line trial production cost. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the cooling experimental apparatus described in this invention. Detailed Implementation

[0049] See Figure 1 The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling, as described in this invention, includes the following steps:

[0050] 1) A circular track 1 combined with a trolley 2 is used. The trolley 2 carries the sample 100 in a circular motion via a sample support platform 3. The circular track 1 is an elliptical track consisting of two parallel straight sections and two semicircular sections. At least one cooling spray box 4 is set along the straight sections of the track to cool the upper and / or lower surfaces of the sample. Each cooling spray box 4 includes upper and lower cooling spray boxes. The sample 100 is heated to a set temperature by a heating device 5 that spans the circular track 1 or is set on the trolley 2. During this process, a temperature measuring device 61 set on the trolley 2 measures the temperature of the sample 100. The temperature measuring device 61 transmits the data to the temperature measuring host 62 wirelessly or via wired means. The temperature measuring host 62 is connected to a controller PLC.

[0051] 2) The sample is heated offline or online, and the temperature of the sample is measured by a temperature measuring device installed on the trolley. After the sample reaches the temperature required by the process, the trolley is driven to move along the track, carrying the sample through the cooling spray box in sequence. The trolley carries the heated sample in a circular motion at a constant speed or with a certain acceleration, as specified in the process speed. The sample support platform has a hollow center, and after the sample is fixed to the support platform, the upper and lower surfaces of the sample are unobstructed. As the sample passes through the cooling spray box, the jets emitted from the cooling spray box directly spray onto the sample, simultaneously cooling the upper and lower surfaces of the sample. During this process, the sample is driven through a theoretically infinitely long cooling zone at a set speed, ensuring that the sample is cooled from the initial cooling temperature to the set target temperature under conditions consistent with the production line operating conditions. The sample temperature and cooling rate are monitored and obtained in real time.

[0052] Sample running speed: 0–25 m / s, acceleration: 0–0.5 m / s² 2 ;

[0053] The flow rate adjustment range for each cooling spray box is 0–300 m³ / h. 3 / h, preferably 10-50m 3 Cooling experiments were conducted by setting the flow rate intervals to increase or decrease at intervals of / h;

[0054] The cooling temperature is 700-1000℃. Preferably, the cooling experiment is conducted by setting the temperature increments or decreases of 40-60℃.

[0055] The cooling temperature ranges from room temperature to 800℃. Preferably, the experiment is conducted by setting the temperature increments or decreases of 30℃ to 50℃.

[0056] If there are more than two cooling spray boxes, the spacing between the cooling spray boxes should be consistent with the production line design.

[0057] 3) Perform performance and microstructure tests on the samples;

[0058] 4) Repeat steps 3) and 4) and select cooling control parameters that meet the requirements of performance and organization based on the measured data, including determining the flow rate value, start-up cooling temperature and final cooling temperature corresponding to the optimal cooling rate.

[0059] 5) Adjust the flow rates of the upper and lower spray boxes within a certain range of the flow rate value corresponding to the optimal cooling rate. The adjustment range of the flow rates of the upper and lower spray boxes is 50% to 150% of the measured flow rate value. Preferably, the adjustment range of the flow rate of the upper spray box is 50% to 100% of the measured flow rate value, and the adjustment range of the flow rate of the lower spray box is 100% to 150% of the measured flow rate value.

[0060] Cooling experiments were conducted at different water-to-top ratios according to the production line process speed and the determined start-up and final cooling temperatures. The temperature curves of the upper and lower surfaces of the sample were measured. Based on the fact that the fitting degree of the cooling curves of the upper and lower surfaces of the sample is above 80%, the optimal water-to-top ratio to meet the requirement of uniform cooling in the thickness direction of the steel plate was determined. The designed water-to-top ratio is 3:1 to 1:3; preferably, the water-to-top ratio is 1:1 to 1:2.

[0061] Preferably, in step 2), the cooling rate CR of the steel plate is calculated based on the starting cooling temperature T1, the stopping cooling temperature T2, and the cumulative cooling time t recorded during the experiment. The cumulative cooling time t is in seconds, and the cooling rate ranges from 0 to 1000℃ / s.

[0062] Preferably, in step 3), the performance Xact of the steel plate is measured by a testing device. Xact is considered qualified if it is within the allowable positive and negative tolerance range of the target performance Xtar, i.e., ΔX1≤(Xact-Xtar)≤ΔX2, where ΔX1: negative tolerance, ΔX2: positive tolerance. The target performance and the range of positive and negative tolerances of the steel plate are determined by the user's requirements.

[0063] Preferably, in step 4), the experimental results under different combinations of cooling rate, start-up cooling temperature and stop-down cooling temperature are statistically analyzed, and the combination that meets the product performance is selected for comprehensive comparison. Based on the production line layout and process system, the optimal cooling rate, start-up cooling temperature and stop-down cooling temperature that meet the maximum process window of product production are determined; the preferred start-up cooling temperature is 800~950℃, and the preferred stop-down cooling temperature is 550℃~750℃.

[0064] Preferably, the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable, with the nozzle diameter of the cooling spray box being 3 to 30 mm and the distance between the cooling spray box and the sample surface being 50 to 2200 mm.

[0065] Preferably, the spacing between the cooling spray boxes is 0–1.5 m, and the flow rate of the cooling spray boxes is 0–300 m³ / h. 3 / h, the number of nozzles in the cooling spray box is 1 to 200; the length of the cooling spray box is 100 to 6000 mm.

[0066] Preferably, the vehicle is driven by an electric motor or by traction.

[0067] Preferably, the circular motion speed of the sample, i.e., linear velocity or angular velocity, is monitored in real time, and the velocity of the sample can be changed online according to the measured temperature data based on the predetermined cooling process, i.e., increasing speed, decreasing speed, or maintaining a constant speed.

[0068] Preferably, the sample is heated offline or online. Preferably, the offline heating method involves heating the sample to the required process temperature, then fixing it on the sample support platform. When the sample approaches the predetermined cooling temperature, the trolley is driven to move along the circular track, carrying the sample through the cooling spray box, i.e., through a theoretically infinitely long cooling zone, to complete the cooling or heat treatment process. The online heating method involves fixing the sample on the sample support platform first, then heating it. When the required process temperature is reached, the heating device is removed from the circular track area, and then the trolley is driven to move along the circular track to complete the cooling or heat treatment process.

[0069] Preferably, the heating is performed using resistance heating, that is, the sample is held on both sides by electrodes and heated directly online by a large current; or, induction heating is performed.

[0070] Preferably, water cooling or air cooling is used to cool the sample.

[0071] Example

[0072] Cooling experiments on a 3mm thick steel grade included:

[0073] 1) Cooling spray box layout

[0074] The distance between the cooling spray box and the sample surface, as well as the nozzle diameter, are the same as those of a certain production line where the flow rate of the cooling spray box after rolling is not adjustable. The distance between the cooling spray box and the upper surface of the sample is 1.8 meters, the distance between the cooling spray box and the lower surface of the sample is 0.15 meters, and the nozzle diameter is 22 mm.

[0075] The spacing between the cooling spray boxes in the experimental setup is the same as that of a production line where the flow rate of the cooling spray boxes after rolling is not adjustable. The spacing is 0.36m, with 6 sets of spray boxes arranged on one side and a cooling zone length of 2.16m, for a total of 12 sets of spray boxes on both sides.

[0076] The production line cooling spray box is 2m long, and the flow rate of a single upper spray box is 108m³. 3 / h, the flow rate of a single lower spray box is 108m³ / h 3 / h;

[0077] The length of the cooling spray box in the experimental setup is 0.5m;

[0078] The maximum flow rate of a single top spray box in the experimental setup is 10⁸ m³. 3 / h*0.5 / 2=27m 3 / h;

[0079] The maximum flow rate of a single lower spray box in the experimental setup is 17 m³ / s. 3 / h*0.5 / 2=27m 3 / h.

[0080] 2) Experimental determination of process parameters for uniform cooling of hot-rolled plates in the thickness direction

[0081] The optimal cooling rate determined in a cooling experiment for a certain steel grade with a thickness of 3mm was 32℃ / s, with a corresponding cooling spray box flow rate of 18m³ / s. 3 / h.

[0082] Experimental schemes were designed according to different combinations of flow rates and water ratios of the upper and lower spray boxes, as shown in Table 1. The initial cooling temperature was 850℃ and the final cooling temperature was 600℃. Steel plate embedded coupling cooling experiments were conducted. The running speed of the steel plate was set to 12m / s according to the actual production line. The fitting degree of the cooling curve of the steel plate after cooling under different flow rates and water ratios of the upper and lower spray boxes was measured, and the experimental results are shown in Table 1.

[0083] The fitting degree of the cooling curves of the steel plates after cooling was analyzed under different combinations of flow rates and water ratios in the upper and lower spray boxes. Taking into account the conditions of the processes before and after the production line and the cooling control window, the parameter No. 4 was finally selected as the process parameter for the production line, namely, an upper spray flow rate of 13.5 m³ / h. 3 / h, downward spray flow rate 18m 3 The ratio of water to water is 1:1.333.

[0084] Table 1. Fitting degree of cooling curves of steel plates cooled under different flow rates of upper and lower spray boxes.

[0085]

Claims

1. An experimental method for determining the optimal water ratio for uniform cooling along the thickness of a hot-rolled plate, characterized in that, Includes the following steps: 1) A circular track combined with a trolley is used. The trolley carries the sample through the sample support platform and makes a circular motion. The circular track is an elliptical track containing two parallel straight sections and two semicircular sections. At least one cooling spray box is set along the straight section of the track to cool the upper and / or lower surface of the sample. Each cooling spray box includes upper and lower cooling spray boxes. 2) The sample is heated offline or online, and the temperature of the sample is measured by a temperature measuring device installed on the trolley. After the sample reaches the temperature required by the process, the trolley is driven to move along the track, carrying the sample through the cooling spray box in sequence. The trolley carries the heated sample in a circular motion at a constant speed or with a certain acceleration, as specified in the process speed. The sample support platform has a hollow center, and after the sample is fixed to the support platform, the upper and lower surfaces of the sample are unobstructed. As the sample passes through the cooling spray box, the jets emitted from the cooling spray box directly spray onto the sample, cooling both the upper and lower surfaces of the sample simultaneously. During this process, the sample is driven through a theoretically infinitely long cooling zone at a set speed, ensuring that the sample is cooled from the initial cooling temperature to the set target temperature under conditions consistent with the production line operating conditions. The sample temperature and cooling rate are monitored and obtained in real time. Sample running speed: 0~25m / s, acceleration: 0~0.5m / s² 2 ; The flow rate adjustment range for each cooling spray box is 0~300m³. 3 / h; The cooling temperature is 700~1000℃; The cooling stop temperature is room temperature to 800℃; If there are more than two cooling spray boxes, the spacing between the cooling spray boxes should be consistent with the production line design. 3) Perform performance and microstructure tests on the samples; 4) Repeat steps 3) and 4), and select cooling control parameters that meet the requirements in terms of performance and organization based on the measured data, including determining the flow rate value, start-up cooling temperature and final cooling temperature corresponding to the optimal cooling rate; 5) Adjust the flow rate of the upper and lower spray boxes within a certain range corresponding to the optimal cooling rate. The adjustment range of the flow rate of the upper and lower spray boxes is 50% to 150% of the measured flow rate value. Cooling experiments were conducted at different water-to-water ratios based on the production line process speed and the determined start-up and final cooling temperatures. The temperature curves of the upper and lower surfaces of the samples were measured. Based on the fact that the fitting degree of the cooling curves of the upper and lower surfaces of the samples was over 80%, the optimal water-to-water ratio to ensure uniform cooling of the steel plate in the thickness direction was determined. The designed water-to-water ratio was 3:1 to 1:

3.

2. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, Step 2) Based on the starting cooling temperature T1, stopping cooling temperature T2 and cumulative cooling time t recorded during the experiment, calculate the cooling rate CR of the steel plate = (starting cooling temperature T1 - stopping cooling temperature T2) / cumulative cooling time t, where the cumulative cooling time t is in seconds; the cooling rate range is 0~1000℃ / s.

3. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, Step 3) Measure the performance Xact of the steel plate using a testing device. If Xact is within the allowable positive and negative tolerance range of the target performance Xtar, it is considered qualified, that is, ΔX1≤(Xact-Xtar)≤ΔX2, where ΔX1: negative tolerance, ΔX2: positive tolerance. The target performance and positive and negative tolerance range of the steel plate are determined by the user's requirements.

4. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, In step 4), the experimental results under different combinations of cooling rate, start-up cooling temperature and stop-down cooling temperature are statistically analyzed. The combination that meets the product performance is selected for comprehensive comparison. Based on the production line layout and process system, the optimal cooling rate, start-up cooling temperature and stop-down cooling temperature that meet the maximum process window of product production are determined.

5. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 4, characterized in that, In step 4), the cooling temperature is 800~950℃.

6. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 4 or 5, characterized in that, In step 4), the cooling temperature is 550℃~750℃.

7. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, The distance between the cooling spray box and the sample surface, as well as the nozzle diameter, are adjustable. The nozzle diameter of the cooling spray box is 3~30mm, and the distance between the cooling spray box and the sample surface is 50~2200mm.

8. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1 or 7, characterized in that, The spacing between cooling spray boxes is 0~1.5m, and the flow rate of the cooling spray boxes is 0~300m³. 3 / h, the number of nozzles in the cooling spray box is 1~200; the length of the cooling spray box is 100~6000mm.

9. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, The circular motion velocity of the sample, i.e., linear velocity or angular velocity, can be monitored in real time, and the velocity of the sample can be changed online according to the measured temperature data according to the predetermined cooling process, i.e., increasing the speed, decreasing the speed, or maintaining a constant speed.

10. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, The sample is heated either offline or online.

11. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 10, characterized in that, The offline heating method involves heating the sample to the required temperature and then fixing it on the sample support platform. When the sample approaches the predetermined cooling temperature, the trolley is driven to move along the circular track, causing the sample to pass through the cooling spray box in sequence, that is, through the theoretically infinitely long cooling zone, to complete the cooling or heat treatment process. The online heating method involves fixing the sample on the sample support platform and then heating it. When the required temperature is reached, the heating device is removed from the circular track area, and then the trolley is driven to move along the circular track to complete the cooling or heat treatment process.

12. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, 10, or 11, characterized in that, Heating is achieved through resistance heating, where electrodes are used to clamp both sides of the sample, and a large current is applied to heat the sample directly online as a resistor; or, induction heating is used.

13. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1 or 11, characterized in that, The sample is cooled by water or air.

14. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, In step 1), the trolley is driven by either a motor or a traction drive.

15. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, In step 2), the flow rate adjustment range for each cooling spray box is 0~300m³. 3 / h, according to 10~50m 3 Cooling experiments were conducted by setting the flow rate intervals to increase or decrease at intervals of / h.

16. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1 or 15, characterized in that, In step 2), the cooling temperature is set to 700~1000℃, and the cooling experiment is conducted by increasing or decreasing the temperature in increments of 40~60℃.

17. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1 or 15, characterized in that, In step 2), the cooling temperature is set from room temperature to 800℃, and the experiment is conducted by increasing or decreasing the temperature in increments of 30℃ to 50℃.

18. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 16, characterized in that, In step 2), the cooling temperature is set from room temperature to 800℃, and the experiment is conducted by increasing or decreasing the temperature in increments of 30℃ to 50℃.

19. The experimental determination method for the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1, characterized in that, In step 5), the flow rate adjustment range of the upper spray box is 50% to 100% of the measured flow rate value, and the flow rate adjustment range of the lower spray box is 100% to 150% of the measured flow rate value.

20. The experimental method for determining the optimal water ratio for uniform cooling in the thickness direction after hot plate rolling as described in claim 1 or 19, characterized in that, In step 5), the ratio of water to water is 1:1 to 1:2.

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