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

Abstract

According to the multi-path cooling control method for the non-adjustable flow of the cooling spray box after hot plate rolling, the mode that an annular rail is combined with a trolley is adopted, the trolley bears a sample through a sample bearing table to do annular motion, the annular rail is an oval rail comprising two parallel linear segments and two semicircular segments, and at least one cooling spray box is arranged along the linear segment rail; the cooling area can be infinitely lengthened at any workpiece speed; according to the cooling starting temperature, the water cooling speed, the cooling stopping temperature, the cooling stopping time between the cooling areas and the production line cooling spray box layout of the N cooling areas determined by the experiment, the experiment device is configured according to different spray box opening modes, the cooling experiment is carried out, and spray box opening mode parameters corresponding to the optimal cooling speed of the N cooling areas are obtained; carrying out cooling control after rolling on corresponding sample production; besides, the method is implemented under the condition basically consistent with the actual working condition of the production line, so that the product design output and the production line process control are more accurate and efficient, the product research and development speed can be effectively increased, the process control precision is improved, and the production line trial-manufacturing cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a multi-path cooling control method for a hot plate after rolling in which the flow rate of a cooling spray box 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] Multi-path cooling technology for hot plate post-rolling involves dividing the post-rolling cooling zone into N cooling zones (N ≥ 2). By controlling the start-up temperature, water cooling rate, stop-cooling temperature, and stop-cooling time between each zone, multi-path cooling is achieved. This utilizes phase transformation to achieve both grain refinement and phase transformation strengthening, resulting in various steel products with superior microstructures, high strength, and high toughness, while simultaneously reducing costs by replacing metal with water. 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 they are typically arranged in a linear configuration. 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, using process parameters obtained from a test mill often results in significant differences in hot plate performance after actual production. Furthermore, a thermal simulator cannot capture information about the spray box's open mode. Therefore, it is often necessary to conduct multiple batches of trial rolling on site to find out some simple parameters. For multi-path cooling, more batches of trial rolling are required, which is not only time-consuming, but the parameters found are not necessarily optimal, and the trial production cost is also very high.

[0004] In summary, there is no method or device for realizing an infinite cooling zone at any workpiece speed at home and abroad for controlling the multi-path cooling of hot plate after rolling with an unadjustable flow rate of the cooling spray box. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-path cooling control method for a hot plate after rolling with an unadjustable flow rate of a cooling spray box, which adopts a circular track combined with a trolley method to realize an infinitely long cooling zone at any workpiece speed; according to the experimentally determined starting cooling temperature, water cooling rate, stopping cooling temperature, stopping cooling time between cooling zones and production line cooling spray box layout of N cooling zones, the experimental device is configured according to different spray box opening modes, and cooling experiments are carried out to obtain the spray box opening mode parameters corresponding to the optimal cooling rate of the N cooling zones, and perform post-rolling cooling control on the corresponding sample production; in addition, since the 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 multi-path cooling control method for a hot plate post-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 through a carrier platform and performs circular motion. The circular track is an elliptical track comprising two parallel straight segments and semicircular arc segments at both ends. At least one cooling spray box is provided along the straight segment track to cool the upper and / or lower surfaces of the sample. The carrier platform for fixing the sample is hollowed out in the middle, leaving the upper and lower surfaces of the sample unobstructed. The jet ejected by the cooling spray box is directly sprayed onto the sample, forming two linear cooling zones. The sample is heated to a set temperature by a heating device arranged across the circular track or on the trolley. During this period, the temperature of the sample is measured by a temperature measuring device provided on the trolley.

[0009] 2) The driving trolley drives the sample to reach the specified process speed, maintains a constant speed or accelerates at a certain acceleration, and passes through a theoretically infinite cooling zone in a moving state to ensure that the sample is cooled from the start-cooling temperature to the target temperature under conditions basically consistent with the on-site working conditions. The cooling process temperature is detected in real time, the cooling process time is accumulated in real time, and the cooling stop time is precisely controlled;

[0010] 3) Conduct cooling combination experiments at different flow rates, cooling stop temperatures, and cooling stop times in N cooling zones for samples of specific steel grades and thickness specifications to determine the cooling rate and steel plate properties; the flow rate range is 0 to 300 m 3 / h, preferably at equal flow intervals of 10 to 50 m 3 / h, the cooling temperature range is 500 ~ 1000 ℃, preferably at an equal temperature interval of 40 ~ 60 ℃, the cooling temperature range is 100 ~ 800 ℃, preferably at an equal temperature interval of 30 ~ 50 ℃, the cooling time is 0 ~ 20s, preferably at an equal time interval of 2 ~ 4s; during this period, the sample running speed range is: 0 ~ 25m / s, the acceleration range is 0 ~ 0.5m / s 2 ;

[0011] 4) Calculate the cooling rates of N cooling zones based on the experimentally recorded data, and measure the properties of the steel plate using a detection device; wherein,

[0012] According to the opening temperature T of N cooling zones recorded during the experiment n1 , cooling stop temperature T n2 , cumulative cooling time t n , the cooling rate CR of the steel plate in N cooling zones can be calculated n =(cooling temperature T n1 - Cooling temperature T n2 ) / accumulated cooling time t n , n=1~N; cooling start temperature range is 500~1000℃, cooling stop temperature is 100~800℃, cooling rate range is 0~1000℃ / s;

[0013] The performance Xact of the sample is measured by the detection device. If Xact is within the positive and negative tolerance range allowed by the target performance Xtar, it is considered qualified, that is, ΔX1≤(Xact-Xtar)≤ΔX2; ΔX1:

[0014] Negative tolerance, ΔX2: Positive tolerance, the target performance of the specimen and the positive and negative tolerance range are determined by user requirements;

[0015] 5) Determination of optimal cooling process parameters

[0016] Select the cooling rate, start temperature, stop temperature, and stop time combinations of N cooling zones with qualified performance. Determine the optimal cooling rate, start temperature, stop temperature, and stop time for each zone to meet the maximum process window for product production based on the production line layout and process system. The preferred start temperature for the first cooling zone is 800-950°C, and the stop time between cooling zones is 4-12 seconds.

[0017] 6) Based on the measured optimal cooling rate, start-of-cooling temperature, and final cooling temperature of the N cooling zones, set the cooling spray box in different opening modes to conduct cooling experiments. That is, the cooling spray box is opened in a certain number of groups (the number of interval groups is 0 to 5). The sample running speed is set according to the actual production line. The sample cooling experiment is carried out to measure the sample cooling rate under different opening modes of the N cooling zones;

[0018] 7) Select and determine the optimal spray box opening mode for the N cooling zones based on the proximity between the cooling rate of the steel plate in the N cooling zones and the optimal cooling rate;

[0019] 8) According to the optimal spray box opening mode of the N cooling zones screened by the cooling experiment, the post-rolling cooling of the N cooling zones of the production line is set and controlled.

[0020] Preferably, in step 1), the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable. The basic principle is that the flow rate of cooling water to the sample surface is consistent with the production line design, thereby ensuring that the experimental cooling rate is consistent with the production line site under the premise that the cooling process is consistent with the production line; 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.

[0021] Preferably, in step 1), the spacing, flow rate and number of cooling spray boxes can be adjusted arbitrarily to ensure that the experimental cooling rate is consistent with the production line site under the premise that the cooling process is consistent with the production line; the spacing range of the cooling spray boxes is 0-1.5m, and the flow rate range of the cooling spray boxes is 0-300m 3 / h, the number of cooling spray box nozzles ranges from 1 to 200;

[0022] 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;

[0023] 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;

[0024] The length of the cooling spray box is 100 to 6000 mm.

[0025] Preferably, the trolley is driven by a motor or a traction drive.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Preferably, the sample is cooled by water cooling or air cooling.

[0030] In the multi-path cooling control method for hot plate post-rolling cooling spray box flow rate which is not adjustable according to the present invention:

[0031] The experimental device consists of two parallel straight line segments and two semicircular arc segments forming a circular track. A trolley carrying the sample is arranged on the circular track, and the sample is driven by the trolley to move.

[0032] The specimen can be heated off-line or on-line.

[0033] The driving trolley drives the sample to reach the specified process speed, which can be maintained at a constant speed or accelerated at a certain acceleration.

[0034] Cooling spray boxes are arranged in an array on two straight segments, and the middle of the supporting platform for fixing the sample is hollowed out. When the sample is fixed to the supporting platform, the upper and lower surfaces of the sample are unobstructed, and the jets from the cooling spray boxes can be directly sprayed onto the sample, forming two straight cooling zones, which can simultaneously perform double-sided cooling on the upper and lower surfaces.

[0035] The sample is driven to any specified speed (slow, medium or high) and passes through a theoretically infinite cooling zone in motion 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; sample temperature range: 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: 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 can be adjusted arbitrarily. The basic principle is that the flow density of cooling water to the sample surface 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] Multi-path cooling control with non-adjustable flow rate of cooling spray box after sample rolling:

[0046] According to the optimal cooling rate of N cooling zones and the layout of the cooling spray boxes of the production line determined by the experiment, the experimental device was configured with different spray box opening modes, and cooling experiments were carried out to obtain the optimal spray box opening mode parameters. According to the spray box opening mode parameters, conventional cooling control of the sample after rolling was carried out.

[0047] According to the measured optimal cooling rate, start cooling temperature and final cooling temperature of N cooling zones, different opening modes of the cooling spray box are set to carry out 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 a steel plate buried cooling experiment is carried out to measure the cooling rate of the sample under different opening modes of N cooling zones.

[0048] According to the proximity between the cooling rate of the steel plate in the N cooling zones and the optimal cooling rate, the optimal spray box opening mode of the N cooling zones is selected and determined.

[0049] According to the optimal spray box opening mode of N cooling zones screened by cooling experiments, the post-rolling cooling of N cooling zones of the production line is set and controlled.

[0050] Beneficial effects of the present invention:

[0051] The present invention adopts a circular track combined with a trolley. The trolley carries the sample through the sample carrying platform to perform circular motion. The circular track is an elliptical track including two parallel straight segments and two semicircular segments. At least one cooling spray box is arranged along the straight segment track to achieve an infinitely long cooling zone at any workpiece speed.

[0052] Based on the experimentally determined N cooling zones' start-up temperatures, water cooling rates, stop-cooling temperatures, stop-cooling times between cooling zones, and the layout of the cooling spray boxes in the production line, the experimental device was configured with different spray box opening modes. Cooling experiments were conducted to obtain the spray box opening mode parameters corresponding to the optimal cooling rates in the N cooling zones, and to control post-rolling cooling for the corresponding hot plate production.

[0053] In addition, since the 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 product development speed, improve the process control accuracy, and reduce the production line trial production cost. After applying this technology to determine the optimal process parameters and feasible cooling control methods that meet the maximum process window for product production, the product design output and production line process control are more accurate and efficient, effectively accelerating the product development speed, improving the process control accuracy and stability, and reducing the production line trial production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the cooling experimental device of the present invention. DETAILED DESCRIPTION

[0055] See also Figure 1 The multi-path cooling control method for hot plate post-rolling cooling spray box flow rate is not adjustable, which comprises the following steps:

[0056] 1) A circular track 1 is combined with a trolley 2. The trolley 1 carries the sample 100 through the carrier 3 to perform 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 cooling spray box 4 for cooling the upper surface and / or lower surface of the sample 100 is arranged along the straight segment track. The carrier 3 for fixing the sample is hollow in the middle, and the upper and lower surfaces of the sample are unobstructed. The jet ejected by the cooling spray box 4 is directly sprayed onto the sample to form two linear cooling zones; each cooling spray box 4 includes an upper and a lower cooling spray box; the sample 100 is heated to a set temperature by a heating device 5 arranged across the circular track 1 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;

[0057] 2) The driving trolley drives the sample to reach the specified process speed, maintains a constant speed or accelerates at a certain acceleration, and passes through a theoretically infinite cooling zone in a moving state to ensure that the sample is cooled from the start-cooling temperature to the target temperature under conditions basically consistent with the on-site working conditions. The cooling process temperature is detected in real time, the cooling process time is accumulated in real time, and the cooling stop time is precisely controlled;

[0058] 3) Conduct cooling combination experiments at different flow rates, cooling stop temperatures, and cooling stop times in N cooling zones for samples of specific steel grades and thickness specifications to determine the cooling rate and steel plate properties; the flow rate range is 0 to 300 m 3 / h, preferably at equal flow intervals of 10 to 50 m 3 / h, the cooling temperature range is 500 ~ 1000 ℃, preferably at an equal temperature interval of 40 ~ 60 ℃, the cooling temperature range is 100 ~ 800 ℃, preferably at an equal temperature interval of 30 ~ 50 ℃, the cooling time is 0 ~ 20s, preferably at an equal time interval of 2 ~ 4s; during this period, the sample running speed range is: 0 ~ 25m / s, the acceleration range is 0 ~ 0.5m / s 2 ;

[0059] 4) Calculate the cooling rates of N cooling zones based on the experimentally recorded data, and measure the properties of the steel plate using a detection device; wherein,

[0060] According to the opening temperature T of N cooling zones recorded during the experiment n1 , cooling stop temperature T n2 , cumulative cooling time t n , the cooling rate CR of the steel plate in N cooling zones can be calculated n =(cooling temperature T n1 - Cooling temperature T n2 ) / accumulated cooling time t n , n=1~N; cooling start temperature range is 500~1000℃, cooling stop temperature is 100~800℃, cooling rate range is 0~1000℃ / s;

[0061] The performance Xact of the sample is measured by the detection device. If Xact is within the positive and negative tolerance range allowed by the target performance Xtar, it is considered qualified, that is, ΔX1≤(Xact-Xtar)≤ΔX2; ΔX1:

[0062] Negative tolerance, ΔX2: Positive tolerance, the target performance of the specimen and the positive and negative tolerance range are determined by user requirements;

[0063] 5) Determination of optimal cooling process parameters

[0064] Select the cooling rate, start temperature, stop temperature and stop time combination of N cooling zones with qualified performance, and determine the optimal cooling rate, start temperature, stop temperature and stop time of the N cooling zones that meet the maximum process window of product production based on the production line layout and process system;

[0065] The preferred starting temperature of the first cooling zone is 800-950°C, and the cooling time between cooling zones is 4-12s;

[0066] 6) Based on the measured optimal cooling rate, start-of-cooling temperature, and final cooling temperature of the N cooling zones, set the cooling spray box in different opening modes to conduct cooling experiments. That is, the cooling spray box is opened in a certain number of groups (the number of interval groups is 0 to 5). The sample running speed is set according to the actual production line. The sample cooling experiment is carried out to measure the sample cooling rate under different opening modes of the N cooling zones;

[0067] 7) Select and determine the optimal spray box opening mode for the N cooling zones based on the proximity between the cooling rate of the steel plate in the N cooling zones and the optimal cooling rate;

[0068] 8) According to the optimal spray box opening mode of the N cooling zones screened by the cooling experiment, the post-rolling cooling of the N cooling zones of the production line is set and controlled.

[0069] Preferably, in step 1), the distance between the cooling spray box and the sample surface and the nozzle diameter are arbitrarily adjustable. The basic principle is that the flow rate of cooling water to the sample surface is consistent with the production line design, thereby ensuring that the experimental cooling rate is consistent with the production line site under the premise that the cooling process is consistent with the production line; 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.

[0070] Preferably, in step 1), the spacing, flow rate and number of cooling spray boxes can be adjusted arbitrarily to ensure that the experimental cooling rate is consistent with the production line site under the premise that the cooling process is consistent with the production line; the spacing range of the cooling spray boxes is 0-1.5m, and the flow rate range of the cooling spray boxes is 0-300m 3 / h, the number of cooling spray box nozzles ranges from 1 to 200;

[0071] 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;

[0072] 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;

[0073] The length of the cooling spray box is 100 to 6000 mm.

[0074] Preferably, the trolley is driven by a motor or a traction drive.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] Preferably, the sample is cooled by water cooling or air cooling.

[0079] Example

[0080] The cooling control method for a certain type of steel with a thickness of 3 mm includes:

[0081] 1) Cooling spray box layout of the experimental device

[0082] The spray box spacing of 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 spray boxes are arranged on one side, and the cooling zone length is 2.16m, with a total of 12 groups of spray boxes on both sides.

[0083] The length of the production line spray box is 2m, and the flow rate of a single upper spray box is 220m 3 / h, the flow rate of a single lower spray box is 220m 3 / h;

[0084] The length of the spray box of the experimental device is 0.5m;

[0085] Experimental device single upper spray box flow rate = 220m 3 / h*0.5 / 2=55m 3 / h;

[0086] Experimental device single lower spray box flow rate = 220m 3 / h*0.5 / 2=55m 3 / h.

[0087] 2) Cooling test according to different spray box opening modes

[0088] The multi-path cooling experiment of two cooling zones showed that the starting cooling temperature of the first cooling zone was 870℃, the final cooling temperature was 680℃, and the optimal cooling rate was 150℃ / s. The starting cooling temperature of the second cooling zone was 680℃, the final cooling temperature was 560℃, and the optimal cooling rate was 70℃ / s.

[0089] 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 8.1. The cooling rate and performance of the steel plate after cooling with different spray box opening modes were measured, and the experimental results in Tables 1 and 2 were obtained.

[0090] Table 1 Cooling rate of the first cooling zone under different opening modes of the upper and lower spray boxes (1 is on, 0 is off)

[0091]

[0092] According to the steel plate performance under different spray box opening modes and the degree of proximity of the cooling rate to the optimal cooling rate, the spray box opening mode of No. 2 in Table 1 was finally selected as the production line process parameter of the first cooling zone.

[0093] Table 2 Cooling rate of the second cooling zone under different opening modes of the upper and lower spray boxes (1 is on, 0 is off)

[0094]

[0095]

[0096] According to the steel plate performance under different spray box opening modes and the degree of proximity of the cooling rate to the optimal cooling rate, the spray box opening mode No. 2 in Table 2 was finally selected as the production line process parameter for the lower cooling zone.

[0097] 3) Determine the production line spray box opening mode

[0098] According to the spray box opening mode of No. 2 in Table 1 and Table 2 selected by the cooling experiment, the post-rolling cooling of the production line was set and controlled, and strip steel with qualified performance was obtained.

Claims

1. A multi-path cooling control method for a hot plate after rolling with a non-adjustable flow rate in a cooling spray box, characterized in that: The steps include: 1) A circular track combined with a trolley is used. The trolley carries the sample through a carrier platform and performs circular motion. The circular track is an elliptical track comprising two parallel straight segments and semicircular arc segments at both ends. At least one cooling spray box is provided along the straight segment track to cool the upper and / or lower surfaces of the sample. The carrier platform for fixing the sample is hollowed out in the middle, leaving the upper and lower surfaces of the sample unobstructed. The jet ejected by the cooling spray box is directly sprayed onto the sample, forming two linear cooling zones. The sample is heated to a set temperature by a heating device arranged across the circular track or on the trolley. During this period, the temperature of the sample is measured by a temperature measuring device provided on the trolley. 2) The driving trolley drives the sample to reach the specified process speed, maintains a constant speed or accelerates at a certain acceleration, and passes through a theoretically infinite cooling zone in a moving state to ensure that the sample is cooled from the start-cooling temperature to the target temperature under conditions basically consistent with the on-site working conditions. The cooling process temperature is detected in real time, the cooling process time is accumulated in real time, and the cooling stop time is precisely controlled; 3) Conduct cooling combination experiments at different flow rates, cooling stop temperatures, and cooling stop times in N cooling zones for samples of specific steel grades and thickness specifications to determine the cooling rate and steel plate properties; the flow rate range is 0 to 300 m 3 / h, preferably at equal flow intervals of 10 to 50 m 3 / h, the cooling temperature range is 500 ~ 1000 ℃, preferably at an equal temperature interval of 40 ~ 60 ℃, the cooling temperature range is 100 ~ 800 ℃, preferably at an equal temperature interval of 30 ~ 50 ℃, the cooling time is 0 ~ 20s, preferably at an equal time interval of 2 ~ 4s; during this period, the sample running speed range is: 0 ~ 25m / s, the acceleration range is 0 ~ 0.5m / s 2 ; 4) Calculate the cooling rates of N cooling zones based on the experimentally recorded data, and measure the properties of the steel plate using a detection device; wherein, According to the opening temperature T of N cooling zones recorded during the experiment n1 , cooling stop temperature T n2 , cumulative cooling time t n , the cooling rate CR of the steel plate in N cooling zones can be calculated n =(cooling temperature T n1 - Cooling temperature T n2 ) / accumulated cooling time t n , n=1~N; cooling start temperature range is 500~1000℃, cooling stop temperature is 100~800℃, cooling rate range is 0~1000℃ / s; The performance Xact of the sample is measured by the testing device. If Xact is within the positive and negative tolerance range allowed by the target performance Xtar, it is considered qualified, that is, ΔX1≤(Xact-Xtar)≤ΔX2; ΔX1: negative tolerance, ΔX2: positive tolerance. The target performance and positive and negative tolerance range of the sample are determined by user needs; 5) Determination of optimal cooling process parameters Select the cooling rate, start temperature, stop temperature, and stop time combinations of N cooling zones with qualified performance. Determine the optimal cooling rate, start temperature, stop temperature, and stop time for each zone to meet the maximum process window for product production based on the production line layout and process system. The preferred start temperature for the first cooling zone is 800-950°C, and the stop time between cooling zones is 4-12 seconds. 6) Based on the measured optimal cooling rate, start-of-cooling temperature, and final cooling temperature of the N cooling zones, set the cooling spray box in different opening modes to conduct cooling experiments, i.e., the cooling spray box is opened in several groups at intervals, with the number of intervals ranging from 0 to 5. The sample running speed is set according to the actual production line, and the sample cooling experiment is conducted to measure the sample cooling rate under different opening modes of the N cooling zones; 7) Select and determine the optimal spray box opening mode for the N cooling zones based on the proximity between the cooling rate of the steel plate in the N cooling zones and the optimal cooling rate; 8) According to the optimal spray box opening mode of the N cooling zones screened by the cooling experiment, the post-rolling cooling of the N cooling zones of the production line is set and controlled.

2. The multi-path 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 1), the distance between the cooling spray box and the sample surface and the nozzle diameter can be adjusted arbitrarily. The basic principle is that the flow rate of cooling water to the sample surface is consistent with the production line design, thereby ensuring that the experimental cooling rate is consistent with the production line site under the premise that the cooling process is consistent with the production line; 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.

3. The multi-path cooling control method for a hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1 or 2, characterized in that: In step 1), the spacing, flow rate and number of cooling spray boxes can be adjusted arbitrarily to ensure that the experimental cooling rate is consistent with the production line on the premise that the cooling process is consistent with the production line; the spacing between cooling spray boxes ranges from 0 to 1.5m, and the flow rate of cooling spray boxes ranges from 0 to 300m 3 / h, the number of cooling spray box nozzles ranges from 1 to 200; 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 is 100 to 6000 mm.

4. The multi-path cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1, characterized in that: The trolley is driven by motor or traction.

5. The multi-path cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to 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.

6. The multi-path cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to 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.

7. The multi-path cooling control method for a hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1 or 6, 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.

8. The multi-path cooling control method for hot plate post-rolling cooling spray box with non-adjustable flow rate according to claim 1 or 6, characterized in that: The sample is cooled by water or air.

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