Conventional cooling control method for non-adjustable flow of cooling spray box after hot plate rolling

Abstract

The invention relates to a conventional cooling control method for non-adjustable flow of a cooling spray box after hot plate rolling, which combines an annular runway with a trolley to configure the space and maximum flow of the cooling spray box of an experimental device according to the layout of a production line under any workpiece speed and an infinitely long cooling area. The method comprises the following steps: carrying out cooling experiments on a sample of a certain steel type and thickness specification at different flows, starting cooling temperatures and final cooling temperatures according to production line process speeds, measuring the cooling rate and the performance of a steel plate, and counting the cooling rate, starting cooling temperature and final cooling temperature combination meeting the product performance; according to the production line layout and the process system, the optimal cooling speed, the initial cooling temperature and the final cooling temperature meeting the maximum process window of product production are determined; and according to the optimal cooling speed, the starting cooling temperature, the final cooling temperature and the production line cooling spray box layout determined by the experiment, configuring the experimental device according to different spray box starting modes, carrying out a cooling experiment to obtain spray box starting mode parameters of the optimal cooling speed, and carrying out cooling control after rolling on corresponding hot plate production.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a conventional cooling control method in which the flow rate of a cooling spray box for hot plate after rolling is not adjustable. Background Art

[0002] The post-rolling cooling zone of the hot plate consists of several upper and lower cooling spray boxes arranged in a certain length area. The post-rolling cooling zone of most production lines is about 100 meters long, and the number of upper and lower spray boxes ranges from dozens to hundreds, which perform symmetrical water cooling on the upper and lower surfaces of the hot plate.

[0003] Conventional post-rolling cooling technology for hot plate involves controlling the cooling rate, start-of-rolling temperature, and final cooling temperature to modify the material's microstructure and meet the hot plate's performance requirements. This cooling technology requires controlling the cooling rate by activating the spray box's open mode when the spray box flow rate cannot be adjusted. Production process parameters are typically obtained using a thermal simulator or hot rolling test mill. However, post-rolling cooling in a hot rolling test mill differs significantly from field conditions, as these mills are typically arranged in a straight line. Therefore, to achieve the same hot plate speed as in-situ, the cooling zone would have to be designed to be nearly 100 meters long, which is clearly unrealistic. Currently, no such test mill exists. Therefore, process parameters obtained using a test mill often differ significantly from actual hot plate performance after field production. Furthermore, a thermal simulator cannot capture information about the spray box's open mode. Therefore, multiple trial rolling runs are often required to determine simple parameters. Multi-path cooling requires even more trial rolling runs, which is time-consuming, not necessarily optimal, and leads to high trial production costs.

[0004] In summary, there is no conventional cooling control method for hot plate post-rolling cooling spray box with unadjustable flow rate based on a method and device for achieving an infinite cooling zone at any workpiece speed at home and abroad. Summary of the Invention

[0005] The purpose of the present invention is to provide a conventional cooling control method for hot plate after rolling with an unadjustable cooling spray box flow rate. By combining a circular runway with a trolley method, the cooling spray box spacing and maximum flow rate of the experimental device are configured according to the production line layout under arbitrary workpiece speed and infinite cooling zone. The cooling experiment is carried out on samples of a certain steel grade and thickness specification at different flow rates, start cooling temperatures and final cooling temperatures according to the production line process speed, the cooling rate and steel plate properties are measured, and the cooling rate, start cooling temperature and final cooling temperature combination that meet the product performance are statistically calculated. The maximum process window for product production is determined according to the production line layout and process system. The optimal cooling rate, start cooling temperature and final cooling temperature of the outlet are determined; according to the optimal cooling rate, start cooling temperature, final cooling temperature and production line cooling spray box layout determined by the experiment, the experimental device is configured according to different spray box opening modes, and a cooling experiment is carried out to obtain the spray box opening mode parameters with the optimal cooling rate, and the post-rolling cooling of the corresponding hot plate production is controlled; since the cooling control method of the present 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 research and development speed, improve the process control accuracy, and reduce the production line trial production cost.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A conventional cooling control method for a hot plate after rolling cooling spray box with non-adjustable flow rate comprises the following steps:

[0008] 1) A circular track combined with a trolley is used. The trolley carries the sample in a circular motion via a carrying platform. The circular track is an elliptical track comprising two parallel straight segments and two semicircular segments. At least one cooling spray box is provided along the straight segment track to cool the upper and / or lower surface of the sample. Each cooling spray box includes an upper and lower cooling spray box. The sample is heated to a set temperature by a heating device arranged across the circular track or on the trolley. During this time, the sample temperature is measured by a temperature measuring device provided on the trolley.

[0009] 2) Start the trolley, which carries the heated sample in a circular motion at a specified process speed or at a certain acceleration; the sample passes through the cooling spray box, and the jet from the cooling spray box is sprayed onto the sample, cooling the upper and lower surfaces of the sample at the same time; during this period, the sample is driven at a set speed through a theoretically infinite cooling zone to ensure that the sample is cooled from the start-of-cooling temperature to the set target temperature under conditions consistent with the production line working conditions, and the sample temperature and cooling rate are monitored and obtained in real time; wherein,

[0010] Sample running speed: 0~25m / s, acceleration: 0~0.5m / s 2 ;

[0011] The flow rate adjustment range of each cooling spray box is 0~300m 3 / h, preferably, 10 to 50 m 3 / h and other flow rate intervals are set to increase or decrease to conduct cooling experiments;

[0012] The cooling temperature is 700-1000°C. Preferably, the cooling experiment is performed by increasing or decreasing the temperature at intervals of 40-60°C.

[0013] The cooling stop temperature is from room temperature to 800°C. Preferably, the experiment is conducted by increasing or decreasing the temperature by 30-50°C.

[0014] If more than two cooling spray boxes are set, the spacing between the cooling spray boxes should be consistent with the production line design;

[0015] 3) Conduct performance and microstructure tests on the samples;

[0016] 4) Repeat steps 2) to 3) and select cooling control parameters that meet the performance and microstructure requirements based on the measured data; determine the optimal cooling rate, start cooling temperature, and final cooling temperature; conduct cooling experiments with the cooling spray box in different opening modes, i.e., the cooling spray box is opened in a certain number of groups (the number of interval groups is 0 to 5), and the sample running speed is set according to the actual production line. Conduct steel plate cooling experiments and measure the cooling rate of the sample under different opening modes;

[0017] Since the flow rate of the cooling spray box of the production line is not adjustable, the spacing of the cooling spray boxes of the experimental device is the same as that of the production line. The fixed flow rate of the cooling spray box of the experimental device is set as follows:

[0018] Maximum flow rate of the spray box on the experimental device = maximum flow rate of the spray box on the production line * length of the spray box of the experimental device / length of the spray box on the production line;

[0019] Maximum flow rate of the spray box under the experimental device = maximum flow rate of the spray box under the production line * length of the spray box of the experimental device / length of the spray box of the production line;

[0020] The length of the cooling spray box of the experimental device ranges from 100 to 6000 mm;

[0021] 5) Based on the experimental results of step 4), the cooling rates of the samples under different opening modes are compared, and the spray box opening mode closest to the optimal cooling rate determined experimentally is selected to set and control the post-rolling cooling of the production line.

[0022] Preferably, in step 2), based on the start cooling temperature T1, stop cooling temperature T2 and cumulative cooling time t recorded during the experimental process, the cooling rate CR of the steel plate is calculated as follows: (start cooling temperature T1 - stop cooling temperature T2) / cumulative cooling time t, where the cumulative cooling time t is in seconds; the cooling rate range is 0 to 1000°C / s.

[0023] Preferably, in step 3), the performance Xact of the steel plate is measured by a detection device. Xact is considered qualified if it is within the positive and negative tolerance range allowed by the target performance Xtar, that is, ΔX1≤(Xact-Xtar)≤ΔX2, wherein ΔX1: negative tolerance, ΔX2: positive tolerance, and the target performance and positive and negative tolerance range of the steel plate are determined by user needs.

[0024] Preferably, in step 4), the experimental results under different combinations of cooling rate, start cooling temperature and stop cooling temperature are counted, and the combination that meets the product performance is selected for comprehensive comparison. The optimal cooling rate, start cooling temperature and stop cooling temperature that meet the maximum process window of product production are determined according to the production line layout and process system; the preferred start cooling temperature is 800-950°C, and the preferred stop cooling temperature is 550°C-750°C.

[0025] Preferably, the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable. The nozzle diameter of the cooling spray box is 3 to 30 mm, and the distance between the cooling spray box and the sample surface is 50 to 2200 mm.

[0026] Preferably, the spacing between cooling spray boxes is 0-1.5m, and the flow rate of cooling spray boxes is 0-300m 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.

[0027] Preferably, the trolley is driven by a motor or a traction drive.

[0028] Preferably, the circular motion speed of the sample, ie, the linear speed or angular speed, is monitored in real time, and the speed of the sample can be changed online according to the measured temperature data according to the predetermined cooling process, ie, the speed can be increased or decreased or kept constant.

[0029] Preferably, the sample is heated by an offline heating method or an online heating method; preferably, the offline heating method is: after the sample is heated to the temperature required by the process, it is fixedly mounted on the sample carrier, and when it is close to the predetermined cooling temperature, the trolley is driven to move along the circular track, driving 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 is: the sample is first fixedly mounted on the sample carrier, and then heated. When the temperature required by the process is reached, the heating device is separated 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.

[0030] Preferably, the heating is performed by resistance heating, that is, electrodes are used to clamp both sides of the sample, and the sample is directly heated online as a resistor through a large current; or, induction heating is used.

[0031] Preferably, the sample is cooled by water cooling or air cooling.

[0032] In the conventional cooling control method of the present invention in which the flow rate of the cooling spray box after hot plate rolling is not adjustable:

[0033] The experimental device consists of a circular track composed of two parallel straight segments and two semicircular arc segments. A trolley carrying the sample is arranged on the track. The trolley drives the sample to move along the circular track. The sample is driven to reach the specified process speed, which can maintain a constant speed or accelerate at a certain acceleration.

[0034] Cooling spray boxes are arranged in an array on two straight sections to form two straight cooling zones, which can simultaneously perform double-sided cooling on the upper and lower surfaces of the sample.

[0035] The experimental device can drive the sample to any specified speed (low, medium or high speed), and pass through the theoretically infinite cooling zone in the moving state to ensure that the sample is cooled from the start-cooling temperature to the target temperature under conditions that are basically consistent with the on-site working conditions.

[0036] 1) The water cooling process is completed in the straight line section, which improves the consistency between the experimental and production line conditions;

[0037] 2) The sample speed is adjustable and controllable in a wide range, the sample speed range is: 0 ~ 25m / s, the acceleration range is 0 ~ 0.5m / s 2 ;

[0038] 3) Infinite cooling can meet the cooling needs of any temperature range. The sample temperature range is: room temperature ~ 1000℃;

[0039] 4) Real-time temperature detection during cooling process, precise control of cooling start and stop temperatures, sample temperature range: room temperature ~ 1000℃;

[0040] 5) The cooling process time is accumulated in real time, and the cooling stop time is precisely controlled to meet the control needs of the phase change time. The cooling time and cooling stop time range from 0 to infinite.

[0041] The distance between the cooling spray box and the sample surface and the nozzle diameter of the experimental device can be adjusted arbitrarily. 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.

[0042] The spacing, flow rate and number of nozzles of the cooling spray boxes of the experimental device can be adjusted arbitrarily. The basic principle is that the flow density of cooling water to the surface of the specimen should be kept as consistent as possible with the production line design.

[0043] The experimental setup's cooling box's distance from the specimen surface and its nozzle diameter are adjustable. The fundamental principle is to keep the cooling water flow rate to the specimen surface consistent with the production line design. This is because the water-cooling heat exchange capacity is closely related to the water flow rate across the specimen surface. This ensures that the experimental cooling rate is consistent with the field, while maintaining consistency with the production line. The nozzle diameter of the cooling box ranges from 3 to 30 mm, and the distance from the cooling box to the specimen surface ranges from 50 to 2200 mm.

[0044] The cooling spray box spacing, flow rate, and number of nozzles in the experimental device are adjustable. The basic principle is that the flow density of cooling water to the sample surface should be as consistent as possible with the production line design. This is an important technical core point for fitting the on-site working conditions, because the water cooling heat exchange capacity is closely related to the flow density of water on the sample surface. This can ensure that the experimental cooling rate is consistent with the on-site cooling process under the premise of being consistent with the production line. The cooling spray box spacing range is 0 to 1.5m, and the cooling spray box flow range is 0 to 300m 3 / h, the number of cooling spray box nozzles ranges from 0 to 200,

[0045] When the spray box spacing of the experimental device is the same as that of the production line, it can be simply converted according to the ratio of the spray box length:

[0046] Maximum flow rate of the spray box on the experimental device = maximum flow rate of the spray box on the production line * length of the spray box of the experimental device / length of the spray box on the production line;

[0047] The maximum flow rate of the spray box under the experimental device = the maximum flow rate of the spray box under the production line * the length of the spray box of the experimental device / the length of the spray box of the production line.

[0048] Conventional cooling control of hot plate after rolling with non-adjustable spray box flow rate:

[0049] Under experimental conditions that are highly consistent with the production line conditions and process regulations, the process parameters of conventional cooling products after rolling for a certain steel grade and thickness specification can be determined more accurately and efficiently, making production and control easier.

[0050] According to the measured optimal cooling rate, start cooling temperature and final cooling temperature, the cooling spray box is set to different opening modes for cooling experiments, that is, the cooling spray box is opened in several groups (the number of interval groups is 0 to 5). The steel plate running speed is set according to the actual production line, and the steel plate buried cooling experiment is carried out to measure the cooling rate of the sample under different opening modes.

[0051] According to the above experimental results, the cooling rates of the samples under different opening modes were compared, and the spray box opening mode closest to the optimal cooling rate measured in the experiment was selected to set and control the post-rolling cooling of the production line.

[0052] Beneficial effects of the present invention:

[0053] The present invention designs a circular runway combined with a trolley method, which realizes the cooling spray box spacing and maximum flow rate of the experimental device configured according to the production line layout under arbitrary workpiece speed and infinite cooling zone. Cooling experiments are carried out on samples of a certain steel grade and thickness specification at different flow rates, starting cooling temperatures and final cooling temperatures according to the production line process speed, and the cooling rate and steel plate properties are measured. The combinations of cooling rate, starting cooling temperature and final cooling temperature that meet the product performance are statistically analyzed. The optimal cooling rate, starting cooling temperature and final cooling temperature that meet the maximum process window of product production are determined according to the production line layout and process system.

[0054] According to the optimal cooling rate, start cooling temperature, final cooling temperature and production line cooling spray box layout determined by the experiment, the experimental device was configured according to different spray box opening modes, and cooling experiments were carried out to obtain the spray box opening mode parameters with the optimal cooling rate, and post-rolling cooling control was carried out for the corresponding hot plate production.

[0055] In addition, since the cooling control method described in the present 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 speed of product development, improve process control accuracy, and reduce the production line trial production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of the cooling experimental device of the method of the present invention. DETAILED DESCRIPTION

[0057] See also Figure 1 The conventional cooling control method for hot plate post-rolling cooling spray box flow rate is not adjustable, which comprises the following steps:

[0058] 1) A circular track 1 is combined with a trolley 2. The trolley 2 carries the sample 100 through the carrier 3 to make a circular motion. The circular track 1 is an elliptical track comprising two parallel straight segments and semicircular arc segments at both ends. At least one surface of the sample and / or the sample is provided along the straight segment track.

[0059] The cooling spray box 4 for cooling the lower surface is hollowed out in the middle of the carrier platform for fixing the sample, and the upper and lower surfaces of the sample are unobstructed. The jets ejected by the cooling spray box 4 are directly sprayed onto the sample 100, forming two linear cooling zones. The sample 100 is heated to a set temperature by a heating device 5 arranged across the circular track or on the trolley 2. During this period, the temperature of the sample 100 is measured by a temperature measuring device 61 arranged on the trolley 2. The temperature measuring device 61 transmits data to a temperature measuring host 62 by wireless or wired means, and the temperature measuring host 62 is connected to a controller PLC.

[0060] 2) Start the trolley, which carries the heated sample in a circular motion at a specified process speed or at a certain acceleration; the sample passes through the cooling spray box, and the jet from the cooling spray box is sprayed onto the sample, cooling the upper and lower surfaces of the sample at the same time; during this period, the sample is driven at a set speed through a theoretically infinite cooling zone to ensure that the sample is cooled from the start-of-cooling temperature to the set target temperature under conditions consistent with the production line working conditions, and the sample temperature and cooling rate are monitored and obtained in real time; wherein,

[0061] Sample running speed: 0~25m / s, acceleration: 0~0.5m / s 2 ;

[0062] The flow rate adjustment range of each cooling spray box is 0~300m 3 / h, preferably, 10 to 50 m 3 / h and other flow rate intervals are set to increase or decrease to conduct cooling experiments;

[0063] The cooling temperature is 700-1000°C. Preferably, the cooling experiment is performed by increasing or decreasing the temperature at intervals of 40-60°C.

[0064] The cooling stop temperature is from room temperature to 800°C. Preferably, the experiment is conducted by increasing or decreasing the temperature by 30-50°C.

[0065] If more than two cooling spray boxes are set, the spacing between the cooling spray boxes should be consistent with the production line design;

[0066] 3) Conduct performance and microstructure tests on the samples;

[0067] 4) Repeat steps 2) to 3) and select cooling control parameters that ensure that the performance and structure meet the requirements based on the measured data; determine the optimal cooling rate, start cooling temperature, and final cooling temperature;

[0068] The cooling spray box is set to different opening modes for cooling experiments, that is, the cooling spray box is opened in several groups (the number of interval groups is 0 to 5). The sample running speed is set according to the actual production line. The steel plate cooling experiment is carried out to measure the sample cooling rate under different opening modes;

[0069] Since the flow rate of the cooling spray box of the production line is not adjustable, the spacing of the cooling spray boxes of the experimental device is the same as that of the production line. The fixed flow rate of the cooling spray box of the experimental device is set as follows:

[0070] Maximum flow rate of the spray box on the experimental device = maximum flow rate of the spray box on the production line * length of the spray box of the experimental device / length of the spray box on the production line;

[0071] Maximum flow rate of the spray box under the experimental device = maximum flow rate of the spray box under the production line * length of the spray box of the experimental device / length of the spray box of the production line;

[0072] The length of the cooling spray box of the experimental device ranges from 100 to 6000 mm;

[0073] 5) Based on the experimental results of step 4), the cooling rates of the samples under different opening modes are compared, and the spray box opening mode closest to the optimal cooling rate determined experimentally is selected to set and control the post-rolling cooling of the production line.

[0074] Preferably, in step 2), based on the start cooling temperature T1, stop cooling temperature T2 and cumulative cooling time t recorded during the experimental process, the cooling rate CR of the steel plate is calculated as follows: (start cooling temperature T1 - stop cooling temperature T2) / cumulative cooling time t, where the cumulative cooling time t is in seconds; the cooling rate range is 0 to 1000°C / s.

[0075] Preferably, in step 3), the performance Xact of the steel plate is measured by a detection device. Xact is considered qualified if it is within the positive and negative tolerance range allowed by the target performance Xtar, that is, ΔX1≤(Xact-Xtar)≤ΔX2, wherein ΔX1: negative tolerance, ΔX2: positive tolerance, and the target performance and positive and negative tolerance range of the steel plate are determined by user needs.

[0076] Preferably, in step 4), the experimental results under different combinations of cooling rate, start cooling temperature and stop cooling temperature are counted, and the combination that meets the product performance is selected for comprehensive comparison. The optimal cooling rate, start cooling temperature and stop cooling temperature that meet the maximum process window of product production are determined according to the production line layout and process system; the preferred start cooling temperature is 800-950°C, and the preferred stop cooling temperature is 550°C-750°C.

[0077] Preferably, the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable. The nozzle diameter of the cooling spray box is 3 to 30 mm, and the distance between the cooling spray box and the sample surface is 50 to 2200 mm.

[0078] Preferably, the spacing between cooling spray boxes is 0-1.5m, and the flow rate of cooling spray boxes is 0-300m 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.

[0079] Preferably, the trolley is driven by a motor or a traction drive.

[0080] Preferably, the circular motion speed of the sample, ie, the linear speed or angular speed, is monitored in real time, and the speed of the sample can be changed online according to the measured temperature data according to the predetermined cooling process, ie, the speed can be increased or decreased or kept constant.

[0081] Preferably, the sample is heated by an offline heating method or an online heating method; preferably, the offline heating method is: after the sample is heated to the temperature required by the process, it is fixedly mounted on the sample carrier, and when it is close to the predetermined cooling temperature, the trolley is driven to move along the circular track, driving 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 is: the sample is first fixedly mounted on the sample carrier, and then heated. When the temperature required by the process is reached, the heating device is separated 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.

[0082] Preferably, the heating is performed by resistance heating, that is, electrodes are used to clamp both sides of the sample, and the sample is directly heated online as a resistor through a large current; or, induction heating is used.

[0083] Preferably, the sample is cooled by water cooling or air cooling.

[0084] Example

[0085] Conventional cooling methods for a certain type of steel with a thickness of 4.5 mm include:

[0086] 1) Cooling spray box layout of the experimental device

[0087] The spacing between the cooling spray boxes in the experimental device is the same as that of a certain post-rolling cooling spray box flow rate non-adjustable production line, which is 0.36m. Six groups of cooling spray boxes are arranged on one side, and the cooling zone length is 2.16m, with a total of 12 groups of cooling spray boxes on both sides.

[0088] The cooling spray box length of the production line is 2m, and the flow rate of a single upper spray box is 108m 3 / h, the flow rate of a single lower spray box is 108m 3 / h;

[0089] The cooling spray box of the experimental device is 0.5m long;

[0090] Experimental device single upper spray box flow rate = 108m 3 / h*0.5 / 2=27m 3 / h;

[0091] Experimental device single lower spray box flow rate = 17m 3 / h*0.5 / 2=27m 3 / h.

[0092] 2) Conduct cooling experiments according to different cooling spray box opening modes

[0093] When the initial cooling temperature is 850℃ and the final cooling temperature is 600℃, the optimal cooling rate determined experimentally is 35℃ / s.

[0094] The steel plate embedded cooling experiment was carried out according to different spray box opening modes. The steel plate running speed was set to 8m / s according to the actual production line. Since the production line spray box flow rate is not adjustable, the spray box of the experimental device was set according to the fixed flow rate calculated and determined in step 2). The cooling rate of the steel plate after cooling with different spray box opening modes was measured, and the experimental results are obtained in Table 1.

[0095] Table 1 Cooling speed of upper and lower spray boxes in different opening modes (1 is on, 0 is off)

[0096]

[0097] According to the closeness between the cooling rate of the steel plate under different spray box opening modes and the optimal cooling rate, the spray box opening mode No. 3 was finally selected as the production line process parameter.

[0098] 3) Determine the production line spray box opening mode

[0099] By comparing the cooling rates of the hot plate under different opening modes, the spray box opening mode closest to the optimal cooling rate of 35°C / s measured by the method was selected, namely the spray box opening mode No. 3. The post-rolling cooling of the production line was set and controlled, and strip steel with qualified performance was obtained.

Claims

1. A conventional cooling control method for hot plate after rolling with non-adjustable cooling spray box flow, characterized in that: The steps include: 1) A circular track combined with a trolley is used. The trolley carries the sample in a circular motion via a carrying platform. The circular track is an elliptical track comprising two parallel straight segments and two semicircular segments. At least one cooling spray box is provided along the straight segment track to cool the upper and / or lower surface of the sample. Each cooling spray box includes an upper and lower cooling spray box. The sample is heated to a set temperature by a heating device arranged across the circular track or on the trolley. During this time, the sample temperature is measured by a temperature measuring device provided on the trolley. 2) Start the trolley, which carries the heated sample in a circular motion at a specified process speed or at a certain acceleration; the sample passes through the cooling spray box, and the jet from the cooling spray box is sprayed onto the sample, cooling the upper and lower surfaces of the sample at the same time; during this period, the sample is driven at a set speed through a theoretically infinite cooling zone to ensure that the sample is cooled from the start-of-cooling temperature to the set target temperature under conditions consistent with the production line working conditions, and the sample temperature and cooling rate are monitored and obtained in real time; wherein, Sample running speed: 0~25m / s, acceleration: 0~0.5m / s 2 ; The flow rate adjustment range of each cooling spray box is 0~300m 3 / h, preferably, 10 to 50 m 3 / h and other flow rate intervals are set to increase or decrease to conduct cooling experiments; The cooling temperature is 700-1000°C. Preferably, the cooling experiment is performed by increasing or decreasing the temperature at intervals of 40-60°C. The cooling stop temperature is from room temperature to 800°C. Preferably, the experiment is conducted by increasing or decreasing the temperature by 30-50°C. If more than two cooling spray boxes are set, the spacing between the cooling spray boxes should be consistent with the production line design; 3) Test the performance and microstructure of the samples; 4) Repeat steps 2) to 3) and select cooling control parameters that meet the performance and microstructure requirements based on the measured data; determine the optimal cooling rate, start cooling temperature, and final cooling temperature; conduct cooling experiments with the cooling spray box in different opening modes, i.e., the cooling spray box is opened in a certain number of groups at intervals, with the number of intervals ranging from 0 to 5; set the sample running speed according to the actual production line, conduct steel plate cooling experiments, and determine the sample cooling rate under different opening modes; Since the flow rate of the cooling spray box of the production line is not adjustable, the spacing of the cooling spray boxes of the experimental device is the same as that of the production line. The fixed flow rate of the cooling spray box of the experimental device is set as follows: Maximum flow rate of the spray box on the experimental device = maximum flow rate of the spray box on the production line * length of the spray box of the experimental device / length of the spray box on the production line; Maximum flow rate of the spray box under the experimental device = maximum flow rate of the spray box under the production line * length of the spray box of the experimental device / length of the spray box of the production line; The length of the cooling spray box of the experimental device ranges from 100 to 6000 mm; 5) Based on the experimental results of step 4), the cooling rates of the samples under different opening modes are compared, and the spray box opening mode closest to the optimal cooling rate determined experimentally is selected to set and control the post-rolling cooling of the production line.

2. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1, characterized in that: Step 2) Based on the cooling start temperature T1, cooling stop temperature T2, and cumulative cooling time t recorded during the experiment, calculate the cooling rate CR of the steel plate = (cooling start temperature T1 - cooling stop temperature T2) / cumulative cooling time t, where the cumulative cooling time t is in seconds; the cooling rate range is 0 to 1000°C / s.

3. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1, characterized in that: Step 3) The performance Xact of the steel plate is measured by a detection device. Xact is considered qualified if it is within the positive and negative tolerance range allowed by the target performance Xtar, that is, ΔX1≤(Xact-Xtar)≤ΔX2, where ΔX1: negative tolerance, ΔX2: positive tolerance, and the target performance and positive and negative tolerance range of the steel plate are determined by user needs.

4. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1, characterized in that: In step 4), the experimental results under different combinations of cooling rate, start cooling temperature and stop cooling temperature are counted, and the combination that meets the product performance is selected for comprehensive comparison. The optimal cooling rate, start cooling temperature and stop cooling temperature that meet the maximum process window of product production are determined according to the production line layout and process system; the preferred start cooling temperature is 800-950°C, and the preferred stop cooling temperature is 550°C-750°C.

5. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate as claimed in claim 1, characterized in that: The distance between the cooling spray box and the sample surface and the nozzle diameter can be adjusted arbitrarily. The nozzle diameter of the cooling spray box is 3 to 30 mm, and the distance between the cooling spray box and the sample surface is 50 to 2200 mm.

6. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1 or 5, characterized in that: The spacing between cooling spray boxes is 0 to 1.5m, and the flow rate of cooling spray boxes is 0 to 300m 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.

7. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate as claimed in claim 1, characterized in that: The trolley is driven by motor or traction.

8. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate as claimed in claim 1, characterized in that: The circular motion speed of the sample, i.e. the linear speed or angular speed, is monitored in real time, and the speed of the sample can be changed online according to the measured temperature data according to the predetermined cooling process, i.e. the speed can be increased or decreased or kept constant.

9. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate as claimed in claim 1, characterized in that: The sample is heated by an offline heating method or an online heating method; preferably, the offline heating method is: after the sample is heated to the temperature required by the process, it is fixedly mounted on the sample carrier, and when it is close to the predetermined cooling temperature, the trolley is driven to move along the circular track, driving the sample to pass through the cooling spray box in sequence, that is, through a theoretically infinitely long cooling zone, to complete the cooling or heat treatment process; the online heating method is: the sample is first fixedly mounted on the sample carrier, and then heated. When the temperature required by the process is reached, the heating device is separated from the circular track area, and the trolley is driven to move along the circular track to complete the cooling or heat treatment process.

10. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1 or 9, characterized in that: Heating adopts resistance heating method, that is, electrodes are clamped on both sides of the sample, and the sample is directly heated online as a resistor through a large current; or, induction heating method is adopted.

11. The conventional cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 9, characterized in that: The sample is cooled by water or air.

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