Method for improving c-curl after cold rolling of hot rolled strip

Abstract

The application discloses a method for improving C-warping after layer cooling of hot-rolled strip steel, which comprises the following steps: S1, formulating a C-warping steel type identification table; S2, after receiving information issued by a production manufacturing system, a process control system carries out information checking to determine whether C-warping control flow needs to be carried out, if yes, entering step S3; S3, determining the density of laminar cooling water; S4, determining the opening priority order of upper and lower laminar cooling header of pre-calculated laminar cooling water; S5, determining the opening or reduction priority order of upper and lower laminar cooling header of feedforward control; S6, determining the opening or reduction priority order of upper and lower laminar cooling header of feedback control; S7, the opening array of upper and lower laminar cooling header sends a message to L1, and the opening and closing of valves in the laminar cooling system are controlled. The application can identify the characteristics of the laminar cooling process of hot-rolled products, carry out laminar cooling process control aiming at C-warping, and improve the detection distortion caused by C-warping.

Description

TECHNICAL FIELD

[0001] The present application relates to the quality control technology of hot continuous rolling production process, more particularly, to a method for improving C-curl of hot-rolled strip after laminar cooling. BACKGROUND

[0002] Modern hot continuous rolling strip generally adopts controlled cooling process, that is, through controlling target finishing temperature and target coiling temperature to produce qualified products. At the same time, the size-thickness and width of hot-rolled products also need to meet the tolerance range required by users. The actual control effect of size and temperature needs to be measured by the detection instrument arranged on the production line in real time, so the measurement environment has higher requirements. The detection distortion of the measurement instrument affects the online dynamic adjustment control on one hand, and also interferes with the quality judgment on the other hand. The width of hot-rolled strip is an important quality index, and the unqualified strip needs to be sealed for quality first, which will cause unnecessary quality loss, and even affect the production rhythm and product delivery cycle.

[0003] The width of hot-rolled strip is mainly detected by two width detectors arranged at the outlet of the finishing mill and the inlet of the coiler. When judging the quality, both width curves need to be qualified to automatically determine that the quality is qualified, and if one curve appears negative tolerance, the quality is automatically determined to be unqualified.

[0004] A part of hot-rolled products will occur C-curl after laminar cooling due to the water cooling characteristics of the steel itself, that is, the phenomenon that the middle of the strip is concave and the both sides are raised, so that the width of the strip detected by the width detector arranged after the laminar cooling area and before the inlet of the coiler is smaller than the actual value, that is, negative tolerance phenomenon occurs, causing automatic quality sealing, as shown in Figure 1

[0005] The main existing problems are as follows:

[0006] 1) The existing method for ensuring detection accuracy is imperfect

[0007] The existing method for improving the detection distortion of hot-rolled strip is mainly:

[0008] A. Eliminate the detection distortion caused by instrument faults and other reasons by periodic calibration measurement of the instrument itself.

[0009] B. The detection environment near the instrument is mainly ensured by wiping the instrument detection lens, increasing air blower and other methods to ensure that the detection environment is not affected by water vapor and dust.

[0010] The above method is invalid for the detection distortion caused by the unstable shape of the strip under running state which cannot be accurately recognized by the detection instrument.

[0011] ​2) When the strip steel passes through the laminar cooling area, the upper surface cooling effect is greater than the lower surface, which leads to the concave shape of the upper and lower surfaces of the strip steel due to thermal expansion and cold contraction, that is, the "C-warp" phenomenon occurs. The width detected by the width detector arranged at the entrance of the coiling machine of the laminar cooling area is smaller than the true width of the strip steel, and the width quality information is misjudged due to the width detection distortion.

[0012] 3) According to the existing quality judgment process, when the negative tolerance phenomenon of width detection occurs due to the C-warp of the strip steel, the hot-rolled strip steel needs to be automatically locked, and then the final quality judgment whether it is qualified is performed by manual. On the one hand, it increases the workload and labor intensity of the person, and on the other hand, it affects the logistics and production efficiency. SUMMARY

[0013] In view of the defects in the prior art, the purpose of the present application is to provide a C-warp improvement method for hot-rolled strip steel after laminar cooling, which can identify the characteristics of the laminar cooling process of the hot-rolled product, control the laminar cooling process for the steel type with C-warp phenomenon and width detection distortion, and thus improve the detection distortion caused by C-warp.

[0014] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0015] A C-warp improvement method for hot-rolled strip steel after laminar cooling, comprising the following steps:

[0016] S1, preparing a C-warp steel type identification table;

[0017] S2, after receiving the information issued by the production and manufacturing system, the process control system performs information checking to determine whether the anti-C-warp control process is needed, if yes, step S3 is entered, if not, the normal cooling control and subsequent production process are performed;

[0018] S3, determining the density of the laminar cooling water;

[0019] S4, determining the opening priority order of the upper and lower laminar cooling headers of the laminar cooling water;

[0020] S5, determining the priority order of the opening or reduction of the upper and lower laminar cooling headers for feedforward control;

[0021] S6, determining the priority order of the increase or reduction of the opening of the upper and lower laminar cooling headers for feedback control;

[0022] S7, the opening array of the upper and lower laminar cooling headers sends a message to the basic automation control system (L1), and the opening and closing of the valves in the laminar cooling system are controlled by the L1 (basic automation control system).

[0023] Preferably, the step S1 is specifically prepared as follows:

[0024] In the process control system, the C-crown steel type identification table is established according to the steel type and specification, the C-crown identification is set, and the identification bit is assigned a value = 1.

[0025] Preferably, in the step S2, the process control system performs information checking as follows:

[0026] The process control system checks the steel type and specification information of the received product to be produced. If the C-crown identification is matched to 1, and the quality design laminar cooling mode is "non-dense", the anti-C-crown control process is started.

[0027] Preferably, the step S3 is as follows:

[0028] When ΔT < 200℃, the density of the upper laminar cooling header is selected as 1 / 3 mode, and the density of the lower laminar cooling header is selected as 1 / 1 mode;

[0029] When ΔT ≥ 200℃, the density of the upper laminar cooling header is selected as 1 / 2 mode, and the density of the lower laminar cooling header is selected as 1 / 1 mode;

[0030] Wherein, ΔT is the difference between the target finish rolling temperature and the target coiling temperature of the steel type, that is, the laminar cooling temperature drop; density = laminar cooling header allowed to open number / total laminar cooling header number.

[0031] Preferably, the step S4 is as follows:

[0032] The total number of laminar cooling valves required to reach the target coiling temperature is calculated by the laminar cooling temperature model according to the target finish rolling temperature, the target coiling temperature, the rolling steel type, and the specification information;

[0033] First, the upper and lower laminar cooling headers are distributed in half, wherein the density of the upper laminar cooling header is determined according to the total temperature drop, and the density of the lower laminar cooling header is 1;

[0034] When the number of available laminar cooling valves of the upper laminar cooling header under the index density is less than the required number of open valves, the valves that need to be opened are sequentially increased from front to back according to the laminar cooling valve group number, and each group increases 1 laminar cooling header until the required number of cooling valves is met. If the laminar cooling temperature model calculates that all laminar cooling headers need to be opened, output "cooling capacity is insufficient" to remind to reduce the rolling speed.

[0035] Preferably, the step S5 is as follows:

[0036] According to the dynamic actual finishing temperature and speed correction calculation of the hot-rolled strip finishing outlet, the number of the laminar cooling headers that need to be adjusted is adjusted: if the laminar cooling headers need to be increased, one laminar cooling header is increased each time, and the laminar cooling headers are alternately increased in the order of lower laminar cooling headers first and upper laminar cooling headers second until the number of the laminar cooling headers is adjusted to reach the target value; if the laminar cooling headers need to be reduced, one laminar cooling header is reduced each time, and the laminar cooling headers are alternately adjusted in the order of upper laminar cooling headers first and lower laminar cooling headers second until the number of the laminar cooling headers is adjusted to reach the target value.

[0037] Preferably, the step S6 is specifically as follows:

[0038] According to the dynamic real-time measured coiling temperature value, the number of the laminar cooling headers is dynamically adjusted: if the laminar cooling headers need to be increased, one laminar cooling header is increased each time, and the laminar cooling headers are alternately increased in the order of lower laminar cooling headers first and upper laminar cooling headers second until the number of the laminar cooling headers is adjusted to reach the target value; if the laminar cooling headers need to be reduced, one laminar cooling header is reduced each time, and the laminar cooling headers are alternately adjusted in the order of upper laminar cooling headers first and lower laminar cooling headers second until the number of the laminar cooling headers is adjusted to reach the target value.

[0039] The C-warp improvement method for the hot-rolled strip after laminar cooling provided by the application has the following beneficial effects:

[0040] 1) The application adds a "C-warp steel type" set in the process control machine (L2), that is, a steel type with detection distortion of the coiling inlet width is identified;

[0041] 2) The cooling mode code issued by the production management system (L4) is checked and judged during the L2 laminar cooling control, and special control is performed when the laminar cooling mode is "non-dense";

[0042] 3) The L2 laminar cooling pre-calculation control sets differentiated opening cooling valve density for the "C-warp steel type", and the density mode (1 / 2 or 1 / 3) is determined according to the total temperature drop;

[0043] 4) The L2 laminar cooling dynamic control sets differentiated upper and lower valve adjustment timing (lower header priority) for the "C-warp steel type". BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a width measurement schematic diagram of the C-warp strip after the existing laminar cooling;

[0045] Figure 2 is a flowchart of the C-warp improvement method of the application. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solutions of the present application, the technical solutions of the present application are further explained below in combination with the drawings and examples.

[0047] In combination Figure 2 As shown in the drawings, the present application provides a method for improving C-curl of hot-rolled strip after laminar cooling. The C-curl phenomenon occurs during the laminar cooling process after the strip leaves the finishing mill. The essence of the C-curl phenomenon is that the upper surface of the strip cools faster than the lower surface during the laminar cooling process, which causes the upper surface to shrink due to thermal expansion and contraction, resulting in a concave shape of the strip. This affects the winding width detection effect of the winding width detection device arranged at the outlet of the laminar cooling system and the inlet of the coiler, i.e., the real width of the strip cannot be detected. The basic idea of the present application is to solve the problem of uneven cooling of the upper and lower surfaces of the strip during the laminar cooling process.

[0048] The method mainly includes the following steps:

[0049] S1, establishing a C-curl steel grade identification table:

[0050] In the process control system (L2), a C-curl steel grade identification table is established according to the steel grade and specification, a C-curl identification is set, and the identification bit is assigned a value of 1, as shown in the following table:

[0051] Steel grade Thickness Width Temperature C-up mark a A1 A2 A3 1

[0052] S2, after receiving the information issued by the production system (L3), the process control system (L2) checks the steel grade, thickness, width, and temperature of the received product to be produced, determines whether the C-curl prevention control process is needed, and if so, the C-curl identification is matched to "1" and the quality design laminar cooling method is "non-dense", then step S3 is entered, otherwise, the conventional cooling control and subsequent production process are performed.

[0053] S3, determining the density of the laminar cooling water:

[0054] Considering the matching problem of the total temperature drop of the temperature drop laminar cooling area and the cooling capacity, the difference between the target finishing temperature and the target coiling temperature, i.e., the laminar cooling temperature drop ΔT, is checked for the steel grade that needs to start the C-curl prevention.

[0055] When ΔT < 200℃, the density of the upper layer flow cooling header is selected as 1 / 3, and the density of the lower layer flow cooling header is selected as 1 / 1;

[0056] When ΔT ≥ 200℃, the density of the upper layer flow cooling header is selected as 1 / 2, and the density of the lower layer flow cooling header is selected as 1 / 1;

[0057] Density = number of layer flow cooling headers allowed to be opened / total number of layer flow cooling headers.

[0058] Taking a group of cooling valves with 6 layer flow cooling headers as an example, the density is 1 / 3, and the valve allowed to be opened mode is shown in the following table:

[0059] Laminar cooling header 1 Laminar cooling header 2 Laminar cooling header 3 Laminar cooling header 4 Laminar cooling header 5 Laminar cooling header 6 Available - - Available - -

[0060] The density is 1 / 2, and the valve allowed to be opened mode is shown in the following table:

[0061] Laminar cooling header 1 Laminar cooling header 2 Laminar cooling header 3 Laminar cooling header 4 Laminar cooling header 5 Laminar cooling header 6 Available - Available - Available -

[0062] The density is 1, and the valve allowed to be opened mode is shown in the following table:

[0063] Laminar cooling header 1 Laminar cooling header 2 Laminar cooling header 3 Laminar cooling header 4 Laminar cooling header 5 Laminar cooling header 6 Available Available Available Available Available Available

[0064] S4, determining the opening priority order of the upper and lower layer flow cooling headers of the pre-calculated layer flow cooling water:

[0065] According to the target finish rolling temperature, the target coiling temperature, the rolling steel grade, and the specification information, the total number of layer flow cooling valves required to be opened to reach the target coiling temperature is calculated by the layer flow cooling temperature model;

[0066] First, the upper and lower layer flow cooling headers are distributed in half, wherein the density of the upper layer flow cooling header is determined according to the total temperature drop, and the density of the lower layer flow cooling header is 1;

[0067] When the upper layer flow cooling header is in the index density, the number of all available layer cooling valves is less than the number of valves required to be opened, then the valves required to be opened are increased in order from front to back according to the layer cooling valve group number, and each group increases 1 layer flow cooling header until the required number of cooling valves is met; if the layer flow cooling temperature model calculates that all layer flow cooling headers need to be opened, output “cooling capacity is insufficient” to remind to reduce the rolling speed.

[0068] S5, determining the priority order of the upper and lower layer flow cooling headers opened or reduced by the feedforward control:

[0069] According to the dynamic actual finishing temperature and speed correction calculation of the hot rolled strip finishing outlet, the number of laminar cooling header that needs to be adjusted is calculated: if the laminar cooling header needs to be increased, one laminar cooling header is increased each time, and the order of increasing is alternately increased from the lower laminar cooling header to the upper laminar cooling header, until the number of laminar cooling headers is adjusted to the target value; if the laminar cooling header needs to be reduced, one laminar cooling header is reduced each time, and the order of adjustment is alternately adjusted from the upper laminar cooling header to the lower laminar cooling header, until the number of laminar cooling headers is adjusted to the target value.

[0070] S6, determine the priority order of increasing or reducing the opening of the upper and lower laminar cooling headers of the feedback control:

[0071] According to the dynamic real-time measured coiling temperature value, the number of laminar cooling headers is dynamically adjusted: if the laminar cooling header needs to be increased, one laminar cooling header is increased each time, and the order of increasing is alternately increased from the lower laminar cooling header to the upper laminar cooling header, until the number of laminar cooling headers is adjusted to the target value; if the laminar cooling header needs to be reduced, one laminar cooling header is reduced each time, and the order of adjustment is alternately adjusted from the upper laminar cooling header to the lower laminar cooling header, until the number of laminar cooling headers is adjusted to the target value.

[0072] S7, the upper and lower laminar cooling header opening array sends a message to the basic automation control system (L1), and the opening and closing of the valve in the laminar cooling system is controlled by L1.

[0073] Example 1

[0074] A certain steel enterprise's hot continuous rolling mill produces a certain brand product, and once the steel characteristics in the finishing outlet laminar cooling area are prone to uneven cooling of the upper and lower surfaces of the strip, the cooling effect of the upper surface is greater than that of the lower surface, the strip presents a concave shape, and the width of the strip detected by the coiling width detector in the laminar cooling outlet and the coiling machine inlet area presents a negative tolerance, while the width of the strip at the outlet of the finishing mill is normal. In order to solve the above problems, the above patent scheme is adopted, and the opening mode of the laminar cooling header is adopted according to the temperature drop of 240℃ (target finishing temperature 880℃, target coiling temperature 640℃). The "intensity" of the cooling header is 1 / 2 for the upper header and 1 / 1 for the lower header. After implementation, the strip is flat and straight after passing through the laminar cooling area, and the coiling width detector detects normally.

[0075] Example 2

[0076] For some brand products prone to C-curl phenomenon, the target finishing temperature is 860°C, the target coiling temperature is 640°C, and the temperature drop of the laminar cooling is 180°C. Through information matching, the C-curl control identifier is determined as "1", and the C-curl control process is entered. According to the temperature drop of 180°C, the "density" of the laminar cooling header is determined as: the upper header is in 1 / 3 mode, and the lower header is in 1 / 1 mode. First, according to the target finishing temperature, the target coiling temperature, the target thickness, the target width, and the finishing pass speed, etc., the required cooling water quantity is calculated by the laminar cooling model, and it is confirmed that the available cooling valve header quantity meets the requirements, and then the cooling valve opening array is pre-arranged according to the upper header 1 / 3 mode and the lower header 1 / 1 mode.

[0077] In the strip speed-up rolling process, the number of cooling valves needs to be increased to increase the cooling water quantity to achieve the target coiling temperature. The laminar cooling model calculates the number of cooling valves that need to be opened, and the cooling valve opening sequence is: preferentially opening 1 lower valve cooling header, and if the cooling valve needs to be opened, 1 upper valve cooling header is added, and the sequence is alternately increased in the order of lower first and upper second.

[0078] According to the real-time dynamic detection value of the coiling temperature, feedback control is performed, and the cooling valves in the feedback area are dynamically adjusted. When the actual measured value of the coiling temperature is higher than the upper limit value of the feedback control dead zone, 1 lower valve cooling header in the feedback area is preferentially opened. If the actual coiling temperature is still high in one feedback control period, 1 upper valve cooling header in the feedback area is continuously opened. The cooling headers are alternately increased in the order of lower first and upper second, and the actual value of the coiling temperature is controlled in the feedback control dead zone. When the actual value of the coiling temperature is lower than the lower limit of the feedback control dead zone, the cooling headers in the feedback area need to be reduced, and 1 upper valve cooling header is preferentially closed. If the actual measured value of the coiling temperature is still lower than the lower limit of the feedback control dead zone in one feedback control period, 1 lower valve cooling header in the feedback area is continuously reduced. The cooling headers are alternately reduced in the order of upper first and lower second, and the actual value of the coiling temperature is controlled in the feedback control dead zone. After the implementation, the strip is flat and has no concave shape after passing through the laminar cooling area, and the coiling width detector detects normally.

[0079] Example 3

[0080] A certain brand of product prone to C-curl phenomenon, target finishing temperature 920℃, target coiling temperature 620℃, temperature drop of 300℃. Through information matching, the C-curl control identifier is determined to be "1", and the C-curl control process is entered. The opening mode of the laminar cooling header is determined to be "intensity" of upper header 1 / 2 and lower header 1 / 1 mode according to the temperature drop of 300℃. According to the information of steel grade, size, target finishing temperature, target coiling temperature and rolling speed, the necessary cooling water quantity is calculated by the laminar cooling model, and it is found that the number of available cooling headers under the current cooling header "intensity" mode is insufficient. The laminar cooling system preferentially adjusts the upper valve from 1 / 2 mode to full opening mode from the first group of cooling headers, and increases the opening of the upper valve cooling header from the first group of cooling headers. After calculation, the first group of valves is fully opened to achieve the target temperature drop, so the upper valves of other groups still maintain 1 / 2 mode.

[0081] During the strip speed-up rolling process, the number of cooling valves needs to be increased to achieve the target coiling temperature. The laminar cooling model calculates the number of cooling valves that need to be opened, and the cooling valve opening sequence is: preferentially opening 1 lower valve cooling header, and if further cooling valves need to be opened, then opening 1 upper valve cooling header, and increasing in turn according to the order of lower first and upper second.

[0082] According to the real-time dynamic detection value of the coiling temperature, feedback control is performed, and the cooling valves in the feedback area are dynamically adjusted. When the actual measured value of the coiling temperature is higher than the upper limit value of the feedback control dead zone, 1 lower valve cooling header in the feedback area is preferentially opened. If the actual coiling temperature is still higher in a feedback control period, 1 upper valve cooling header in the feedback area is continuously opened. The cooling headers are increased in turn according to the priority order of lower first and upper second, and the actual value of the coiling temperature is controlled within the feedback control dead zone. When the actual value of the coiling temperature is lower than the lower limit of the feedback control dead zone, the feedback area cooling headers need to be reduced, and 1 upper valve cooling header is preferentially closed. If the actual measured value of the coiling temperature is still lower than the lower limit of the feedback control dead zone in a feedback control period, 1 lower valve cooling header in the feedback area is continuously reduced. The cooling headers are reduced in turn according to the priority order of upper first and lower second, and the actual value of the coiling temperature is controlled within the feedback control dead zone. After the implementation, the strip is straight and has no concave shape after passing through the laminar cooling area, and the coiling width detector detects normally. In summary, the present application can configure special laminar cooling header opening array for "C-curl steel", improve the uniformity of water cooling on the upper and lower surfaces of the strip, and improve the C-curl phenomenon, avoid the distortion of the coiling width detection caused by the uneven cooling of the upper and lower surfaces of the strip when passing through the laminar cooling area, reduce the detection distortion of the coiling width, reduce the manual workload, and ensure smooth logistics.

[0083] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as limitation to the present application, as long as the changes and variations of the above embodiments are within the spirit and scope of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A method for improving C-curl after cold reduction of a hot-rolled steel strip, characterized by, The method comprises the following steps: S1, form a C-camber steel grade identification table, The step S1 is specifically formed as follows: In the process control system, the C-camber steel grade identification table is established according to the steel grade and specification, the "C-camber identification" is set, and the identification bit is assigned a value =1; S2, after the process control system receives the information issued by the production system, the process control system checks the information to determine whether the C-camber prevention control process is needed, if yes, proceed to step S3, if not, proceed to the normal cooling control and subsequent production process; S3, determine the density of the laminar cooling water, the density = the number of laminar cooling header allowed to be opened / the total number of laminar cooling headers; S4, determine the pre-computed opening priority of the upper and lower laminar cooling headers of the laminar cooling water, The step S4 is specifically as follows: The total number of laminar cooling valves required to be opened to reach the target coiling temperature is calculated by the laminar cooling temperature model according to the target finishing temperature, the target coiling temperature, the rolling steel grade and the specification information; Firstly, the upper and lower laminar cooling headers are allocated in half, wherein the density of the upper laminar cooling header is determined according to the total temperature drop, and the density of the lower laminar cooling header is 1; When the number of available laminar cooling valves of the upper laminar cooling header is less than the number of valves required to be opened under the index density, the valves required to be opened are sequentially increased from front to back according to the laminar cooling valve group number, and each group is increased by 1 laminar cooling header until the required number of cooling valves is met; if the laminar cooling temperature model calculates that all laminar cooling headers need to be opened, output a "cooling capacity insufficient" prompt to reduce the rolling speed; S5, determine the priority of the upper and lower laminar cooling headers opened or reduced by the feedforward control; S6, determine the priority of the upper and lower laminar cooling headers increased or reduced by the feedback control; S7, the upper and lower laminar cooling header opening array sends a message to the basic automation control system, and the basic automation control system controls the opening and closing of the valves in the laminar cooling system.

2. The method for improving C-curl after the cold reduction of a hot-rolled steel strip according to claim 1, characterized by, In the step S2, the process control system checks the information as follows: The process control system checks the steel grade and specification information of the product to be produced, and if the "C-camber identification" is matched to 1 and the quality design laminar cooling mode is "non-dense", the C-camber prevention control process is started.

3. The method for improving C-curl after the cold of a hot-rolled steel strip according to claim 1, characterized by, The step S3 is specifically as follows: When ΔT < 200℃, the density of the upper laminar cooling header is selected as 1 / 3, and the density of the lower laminar cooling header is selected as 1 / 1; When ΔT ≥ 200℃, the density of the upper laminar cooling header is selected as 1 / 2, and the density of the lower laminar cooling header is selected as 1 / 1; Wherein, ΔT is the difference between the target finishing temperature and the target coiling temperature of the steel grade, that is, the laminar cooling temperature drop.

4. The method of claim 1, wherein the hot-rolled steel strip is a high-strength steel strip. The step S5 is specifically as follows: According to the dynamic actual finishing temperature and speed correction calculation of the hot-rolled strip finishing outlet, the number of the laminar flow cooling headers that need to be adjusted is adjusted: if the laminar flow cooling headers need to be increased, one of the laminar flow cooling headers is increased each time, and the laminar flow cooling headers are alternately increased in the order of first the lower laminar flow cooling headers and then the upper laminar flow cooling headers until the number of the laminar flow cooling headers is adjusted to reach the target value; if the laminar flow cooling headers need to be reduced, one of the laminar flow cooling headers is reduced each time, and the laminar flow cooling headers are alternately adjusted in the order of first the upper laminar flow cooling headers and then the lower laminar flow cooling headers until the number of the laminar flow cooling headers is adjusted to reach the target value.

5. The method of claim 1, wherein the hot-rolled steel strip is a high-strength steel strip. The step S6 is specifically as follows: According to the dynamic real-time measured coiling temperature value, the number of the laminar flow cooling headers is dynamically adjusted and fed back: if the laminar flow cooling headers need to be increased, one of the laminar flow cooling headers is increased each time, and the laminar flow cooling headers are alternately increased in the order of first the lower laminar flow cooling headers and then the upper laminar flow cooling headers until the number of the laminar flow cooling headers is adjusted to reach the target value; if the laminar flow cooling headers need to be reduced, one of the laminar flow cooling headers is reduced each time, and the laminar flow cooling headers are alternately adjusted in the order of first the upper laminar flow cooling headers and then the lower laminar flow cooling headers until the number of the laminar flow cooling headers is adjusted to reach the target value.

Images