A method for dynamically adjusting three-point difference during hot strip rolling

Abstract

The present invention relates to the field of hot-rolled strip technology, and in particular to a method for dynamically adjusting three-point differences during the hot-rolled strip rolling process. The method includes: S1, pre-rolling preparation and parameter initialization: roll profile matching and model parameter preloading; S2, dynamic control during the strip threading phase: thickness pre-compensation and temperature gradient suppression; S3, steady-state rolling control: real-time monitoring and compensation of three-point differences and dynamic compensation of thermal crown; and S4, tail swing and abnormality handling: tail stability control and intelligent transition material insertion. The present invention constructs a full-process control system encompassing dynamic roll gap control, temperature-stress coupling compensation, and intelligent decision support. By developing an asymmetric bending roll force distribution model and a roll profile matching strategy that adapts to the rolling rhythm, the system effectively addresses the difficulties faced by traditional single-point thickness control, such as the difficulty in suppressing head and tail thickness fluctuations and excessive edge thinning.

Description

Technical Field

[0001] The present invention relates to the technical field of hot-rolled strips, and in particular to a method for dynamically adjusting three-point differences during the rolling process of hot-rolled strip steel. Background Art

[0002] In hot-rolled strip production, the difference in thickness at the head, middle, and tail—referred to as the "three-point spread"—is a key indicator of strip shape quality. The causes of this spread are complex, involving the coupling of multiple factors, including the rolling process, equipment status, and temperature distribution.

[0003] Traditional control methods suffer from the following systemic flaws: The current mainstream hot-rolling thickness control system utilizes a single-point automatic thickness control (AGC) system, which performs closed-loop adjustment only for the middle strip thickness, making it difficult to control thickness fluctuations at the head and tail. Head thickness fluctuations are caused by unstable tension during the threading phase, resulting in a standard deviation of approximately 0.05-0.10mm. Tail thickness fluctuations, caused by a sudden drop in tension during the strip casting phase, can result in tail thickness deviations exceeding 0.10mm. Furthermore, the three-point difference (DGT) rate exceeds the control standard: With traditional AGC systems, the three-point difference (DGT) rate is high, requiring additional trimming. Existing technologies rely on fixed roll-changing cycles and are unable to adapt to dynamic production demands, leading to the following issues: Inadequate adaptability to fast-paced production: When rolling more than 35 pieces per hour, roll thermal crown accumulates at a rate of approximately 0.02mm / 10 minutes, significantly increasing the three-point difference deterioration rate in the second half of the rolling cycle. At slower production speeds, roll wear is uneven. When production speeds are less than 20 pieces per hour, localized roll wear leads to asymmetric roll gaps and a widening thickness difference between the drive and operating sides. The overall negative impact is low economic efficiency. Changing rolls at a fixed rolling tonnage wastes 10-15% of the remaining roll life and increases roll consumption by 0.05kg / t per ton of steel. In addition, the temperature gradient of the finishing process has a particularly significant impact on the three-point difference. There are differences in transverse temperature. When the temperature gradient at the finishing entrance is greater than 25°C, the cooling rate difference between the edge and the middle of the strip reaches 15-20%, triggering lateral flow of metal and resulting in wedge-shaped out-of-tolerance. When the waiting time in the heating furnace is greater than 5 minutes, the temperature difference between the head and tail of the strip widens, the fluctuation range of the three-point difference increases, and the control response time is long. The existing system relies on manual experience to adjust the cooling water volume of the layer. The time required from detecting the temperature anomaly to executing compensation is too long, resulting in the proportion of out-of-tolerance coils reaching more than 10%.

[0004] Patents related to static bending roll force distribution propose a strategy for distributing bending roll forces based on a fixed ratio between the operator side and the transmission side, but this strategy fails to consider the impact of rolling rhythm and roll profile variations. Practical applications have also demonstrated that bending roll force compensation is insufficient during fast-paced production, and that large errors in roll change cycle adaptation lead to excessive roll wear. Temperature gradient compensation methods use infrared thermometers to monitor the transverse temperature distribution and adjust the amount of cooling water. However, these methods are limited by the lack of a temperature-rolling force coupling model, resulting in significant residual temperature errors after compensation. Furthermore, these methods are designed for only a single steel grade, such as low-carbon steel, and have limited adaptability to medium- and high-carbon steels, such as 65Mn. Furthermore, these methods fail to address the stability issues associated with the three-point spread. In recent years, a variety of improvement plans have been proposed in the academic field, but there are still technical gaps. In terms of model predictive control, some studies have used MPC algorithms to optimize roll gap settings, but have not integrated rolling rhythm parameters, and have insufficient adaptability to dynamic working conditions in actual production; some scholars have tried to use neural networks to predict three-point differences, but the model relies on a large amount of historical data training and has poor generalization capabilities for new steel grades and new specifications; some have tried to use virtual rolling simulation to optimize process parameters, but the real-time performance is insufficient and it is difficult to use for online control.

[0005] At this stage, downstream users have upgraded their quality requirements. With the growing demand for high-end products such as automotive plates and home appliance plates, users have increasingly stringent requirements for the uniformity of strip thickness: 1. Strips with three-point differences greater than 0.05mm will cause fluctuations in cold rolling force and lead to the risk of strip breakage. According to relevant literature, the probability increase can reach about 20%; 2. Surface quality indicators: Excessive three-point differences will cause uneven coating thickness, resulting in an increase in the scrap rate of automotive outer panels; 3. Yield bottleneck: Under traditional processes, the amount of trimming caused by excessive three-point differences accounts for 1.5-2.0% of the total width of the strip, especially when producing narrow width products, the amount of trimming will be even higher; 4. Energy consumption and emission reduction pressure: The rolling of redundant transition materials increases gas consumption, resulting in excessively high carbon emission intensity. Summary of the Invention

[0006] To address these issues, the present invention aims to provide a method for dynamically adjusting the three-point gap during the hot strip rolling process. With process optimization and intelligent upgrades as core approaches, this method establishes a comprehensive control system encompassing dynamic roll gap regulation, temperature-stress coupling compensation, and intelligent decision support. By developing an asymmetric bending force distribution model and a roll profile matching strategy that adapts to the rolling rhythm, this method effectively addresses the challenges of traditional single-point thickness control, such as the difficulty in suppressing head and tail thickness fluctuations and excessive edge thinning.

[0007] The technical solution adopted in the present invention is as follows:

[0008] The present invention proposes a method for dynamically adjusting three-point differences during hot strip rolling, comprising the following steps:

[0009] S1. Preparation before rolling and parameter initialization: roll profile matching and model parameter preloading;

[0010] S2. Dynamic control during the threading stage: thickness pre-compensation and temperature gradient suppression;

[0011] S3, Steady-state rolling control: real-time monitoring and compensation of three-point difference, dynamic compensation of thermal crown;

[0012] S4. Tail drift and abnormal handling: tail stability control, intelligent transition material insertion.

[0013] Furthermore, in step S1, the roller type is selected according to the production plan: during fast-paced rolling, the concavity is 0.12~0.15mm to suppress thermal convexity; during slow-paced rolling, the concavity is 0.05~0.08mm to reduce wear; after changing the rollers, the hot roller material is rolled: 5~8 transition materials are rolled, the initial bending roll force is set to 80% of the baseline value, and each roll is increased by 5% to full load.

[0014] Furthermore, in step S1, the model parameter preloading includes: calling the historical optimal parameters of the same specifications from the digital twin platform; calibrating the detection instruments: the zero point error of the laser thickness gauge is ≤0.005mm, and the deviation of the infrared thermometer is ≤±3℃.

[0015] Furthermore, in step S2, thickness pre-compensation includes: predicting the thickness deviation based on the strip head temperature, pre-adjusting the roll gap by 0.10~0.30mm, wherein the roll gap is compensated by +0.05mm for every 10°C decrease in temperature; the bending roll force starts at 90% of the reference value and increases linearly to 100% within 10 seconds.

[0016] Furthermore, in step S2, the temperature gradient suppression includes: temporarily reducing the cooling water volume at the edge to 80% of the standard value to reduce the temperature drop during strip threading; and stabilizing the rolling speed within the first 30 meters at 4.50-4.60 m / s.

[0017] Furthermore, in step S3, the real-time monitoring and compensation of the three-point spread includes:

[0018] Calculate the three-point spread:

[0019] .

[0020] Among them, h L is the thickness of the operating side; hc is the thickness of the middle part; h T is the thickness of the transmission side; △H is the three-point difference;

[0021] Graded Response:

[0022] When ΔH is 0.05~0.08mm, the bending roll force on the operating side increases by 6~10%; the pressure compensation on the transmission side is 0.1~0.3mm; the edge cooling flow rate increases by 10~20%;

[0023] When ΔH>0.08mm, the bending roll force on the operating side increases by 10-15%; the pressure compensation on the transmission side is 0.3~0.5mm; and the edge cooling flow rate increases by 20~30%.

[0024] Furthermore, in step S3, the dynamic compensation of thermal crown includes: updating the compensation amount every 18-22 rolling mills:

[0025]

[0026] Among them, C h (t) is the thermal crown compensation amount; t is the rolling time; v is the rolling speed; N is the cumulative rolling count;

[0027] The roller gap is fine-tuned by hydraulic AGC, and the compensation error is ≤±0.01mm.

[0028] Furthermore, in step S4, the tail stability control includes: reducing the rolling speed to 3.5-4.5 m / s 48-52 meters in advance, reducing the middle cooling water volume to 80-90%; and reducing the bending roll force in a step-by-step manner to 65-75% of the baseline value to suppress tail warping.

[0029] Furthermore, in step S4, the intelligent transition material insertion includes: when the predicted abnormal duration is greater than 5 minutes, inserting one gradual transition material, and compressing the transition section length to 14-16 meters.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Quality improvement: The three-point difference pass rate has been improved to the industry-leading level, meeting the stringent requirements of high-end cold-rolled substrates for thickness uniformity;

[0032] 2. Cost optimization: Transition material consumption and roll wear rate were significantly reduced, and the production cost per ton of steel decreased year-on-year;

[0033] 3. Green Manufacturing: Reduce energy consumption through process optimization and help achieve carbon emission reduction goals;

[0034] 4. Intelligent upgrade: Equipment utilization and production flexibility are greatly improved, supporting efficient production of small batches and multiple varieties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a schematic flow chart of a method for dynamically adjusting three-point differences during the hot strip rolling process. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] It should be noted that, in the description of the present invention, the terms "up", "down", "top", "bottom", "one side", "the other side", "left", "right", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0038] See attached Figure 1 The present invention proposes a method for dynamically adjusting three-point differences during hot strip rolling, comprising the following steps:

[0039] S1. Preparation before rolling and parameter initialization:

[0040] Roller type matching: Select the roller type according to the production plan: When rolling at a fast pace (≥35 pieces / hour), the concavity is 0.12~0.15mm to suppress thermal crown; when rolling at a slow pace (<25 pieces / hour), the concavity is 0.05~0.08mm to reduce wear; Rolling of hot roll materials after roller change: When rolling 5~8 transition materials, the initial bending roll force is set to 80% of the baseline value, and increases by 5% for each piece to full load.

[0041] Preload model parameters; call historical optimal parameters of the same specifications (such as final rolling temperature and cooling intensity) from the digital twin platform; calibrate testing instruments: laser thickness gauge zero point error ≤ 0.005mm, infrared thermometer deviation ≤ ±3℃.

[0042] S2. Dynamic control during the threading phase (speed ≤ 5m / s):

[0043] Thickness pre-compensation: Based on the predicted thickness deviation of the strip head temperature, the roll gap is pre-adjusted by 0.10~0.30mm. Among them, the roll gap compensation is +0.05mm for every 10℃ decrease in temperature. The bending roll force starts at 90% of the reference value and increases linearly to 100% within 10 seconds.

[0044] Temperature gradient suppression: The cooling water volume at the edge is temporarily reduced to 80% of the standard value to reduce the temperature drop during strip threading; the rolling speed within the first 30 meters is stabilized at 4.50~4.60m / s.

[0045] S3, Steady-state rolling control:

[0046] Real-time monitoring and compensation of three-point spread:

[0047] Calculate the three-point spread:

[0048] .

[0049] Among them, h L is the thickness of the operating side; hc is the thickness of the middle part; h T is the thickness of the transmission side; △H is the three-point difference;

[0050] Graded Response:

[0051] When ΔH is 0.05~0.08mm, the bending roll force on the operating side increases by 6~10%; the pressure compensation amount on the transmission side increases by 0.1~0.3mm; and the edge cooling flow rate increases by 10~20%;

[0052] When ΔH>0.08mm, the bending roll force on the operating side increases by 10-15%; the pressure compensation amount on the transmission side increases by 0.3~0.5mm; and the edge cooling flow rate increases by 20~30%.

[0053] Dynamic compensation of thermal crown: the compensation amount is updated every 18-22 rolls:

[0054]

[0055] Among them, C h (t) is the thermal crown compensation amount; t is the rolling time; v is the rolling speed; N is the cumulative rolling count;

[0056] The roller gap is fine-tuned by hydraulic AGC, and the compensation error is ≤±0.01mm.

[0057] S4. Tail drift and exception handling:

[0058] Tail stability control: Reduce the rolling speed to 3.5-4.5 m / s 48-52 m in advance, reduce the cooling water volume in the middle section to 80-90%, and reduce the bending roll force in steps to 65-75% of the baseline value to suppress tail warping.

[0059] Intelligent transition material insertion: When the predicted abnormal duration is greater than 5 minutes, a transition material with a gradual thickness change (such as 6mm→5mm→4mm) is inserted, and the length of the transition section is compressed to 14~16 meters.

[0060] Preparation before rolling and parameter initialization;

[0061] Principle: Ensure that the equipment status and process parameters before rolling are optimal, laying the foundation for the subsequent rolling process.

[0062] Specific means and objectives:

[0063] Roller type matching: Select the appropriate roll type according to the production plan. When rolling at a fast pace, choose a roll type with large concavity to suppress thermal crown. When rolling at a slow pace, choose a roll type with small concavity to reduce wear.

[0064] Purpose: To adapt to different rolling rhythms, reduce roll gap changes, and improve plate shape quality.

[0065] Model parameter preloading: Call the historical optimal parameters of the same specifications from the digital twin platform and calibrate the detection instruments.

[0066] Purpose: To optimize current rolling parameters using historical data, ensure measurement accuracy, and improve the stability and controllability of the rolling process.

[0067] Dynamic adjustment during the threading phase;

[0068] Principle: Pre-compensate the thickness and temperature during the threading stage to reduce the thickness fluctuation and temperature gradient effects in the initial stage.

[0069] Specific means and objectives:

[0070] Thickness pre-compensation: Predict thickness deviation based on strip head temperature and pre-adjust roll gap.

[0071] Purpose: To compensate for thickness changes caused by temperature differences and ensure thickness uniformity at the strip head.

[0072] Temperature gradient suppression: reduce the amount of cooling water at the edge and stabilize the head rolling speed.

[0073] Purpose: To reduce the temperature drop during threading and avoid lateral flow and wedge-shaped deviation caused by temperature gradient.

[0074] Steady-state rolling control;

[0075] Principle: Real-time monitoring of the three-point difference and dynamic compensation, while taking into account the change of thermal crown, to maintain thickness uniformity during steady-state rolling.

[0076] Specific means and objectives:

[0077] Real-time monitoring and compensation of three-point difference: By calculating the three-point difference and responding in stages, the bending force and edge cooling flow on the operating and transmission sides are adjusted.

[0078] Purpose: To correct thickness deviation in time, suppress thickness fluctuation at the head and tail, and improve the pass rate of three-point difference.

[0079] Dynamic compensation of thermal crown: Update the thermal crown compensation amount according to the rolling count, and fine-tune the roll gap through hydraulic AGC.

[0080] Purpose: To compensate for the change in roll gap caused by the change in thermal crown during rolling and to keep the thickness of the middle part of the strip stable.

[0081] tail-flick and exception handling;

[0082] Principle: Control measures are taken during the tail swinging stage to reduce thickness fluctuation and warpage of the tail. At the same time, transition materials are inserted in time when abnormalities occur to maintain production stability.

[0083] Specific means and objectives:

[0084] Tail stability control: reduce rolling speed, middle cooling water volume and bending roll force.

[0085] Purpose: To reduce thickness deviation and warping caused by tail tension loss effect and improve the quality of the strip tail.

[0086] Smart transition material insertion: When the abnormality is predicted to last for a long time, a gradual transition material is inserted.

[0087] Purpose: To smoothly transition abnormal conditions and reduce strip waste and production interruptions caused by abnormalities.

[0088] The present invention will be further described below by means of specific embodiments:

[0089] Example 1

[0090] Q235B, 6.0×790mm conventional steel

[0091] Initial production conditions:

[0092] Steel characteristics: C ≤ 0.10%, Mn 0.20-0.30%, typical low-carbon structural steel; Equipment parameters: Finishing mill stiffness 5800kN / mm, layer cooling system maximum water volume 200m 3 / h; Historical issues: The standard deviation of the three-point spread fluctuation is 0.07mm, the deviation rate is greater than 25%, and the yield rate is 89.3%.

[0093] Technical solution implementation:

[0094] S1. Preparation before rolling:

[0095] A large concavity roller profile (0.12mm) was selected, and after the rollers were changed, 6 hot roller materials (gradual thickness of 7.0~6.5mm) were rolled; the preload parameters of the digital twin platform were: final rolling temperature 890℃, bending roll force reference value OS-820kN / DS-780kN.

[0096] S2, Belt Wearing Stage:

[0097] The strip head temperature was detected to be 870°C (20°C lower than the target), the roll gap pre-compensation was +0.25mm; the edge cooling water volume was set to 80% of the standard value, and the rolling speed was stabilized at 4.55m / s.

[0098] S3, steady-state rolling:

[0099] The real-time monitoring value of the three-point difference ΔH=0.06mm, triggering a first-level response; the operating side bending roller force increased to 902kN (+10%), and the transmission side pressure compensation was 0.3mm; the edge cooling increased to 120%, and after 35 seconds, ΔH dropped to 0.02mm.

[0100] S4, drift control:

[0101] The speed is reduced to 3.5m / s 50 meters in advance, and the cooling water volume in the middle is reduced to 80%; the bending roll force step is reduced to 65% of the baseline value, and the tail three-point difference is stabilized at 0.03mm.

[0102] Implementation effect verification

[0103] Table 4 Comparison of Q235B implementation effects

[0104]

[0105] Example 2

[0106] 65Mn 500×3.5mm high carbon tool steel

[0107] S1. Preparation before rolling and parameter initialization:

[0108] Steel characteristics: C: 0.62-0.70%, Mn: 0.90-1.20%.

[0109] Equipment configuration: Rolling mill stiffness: 6500kN / mm (reinforced support); cooling system: nitrogen atomization cooling (inhibiting oxidation).

[0110] Initial parameters:

[0111]

[0112] S2. Dynamic adjustment during the threading phase: (speed ≤ 5m / s)

[0113] Thickness pre-compensation: Detect the strip head temperature at 825℃ (5℃ lower than the target), roll gap compensation +0.15mm; edge cooling water volume is reduced to 80% (flow rate 144m 3 / h).

[0114] Bending roll force loading: The initial value is set to 90% of the baseline (OS 788kN / DS 735kN) and increases linearly to 100% within 8 seconds.

[0115] S3, steady-state rolling control: (speed 7.5m / s)

[0116] Three-point difference control: Real-time calculation of ΔH=0.08mm (exceeding the limit) triggers the secondary response: operating side bending roll force +12% (to 1176kN), transmission side pressure compensation 0.4mm; edge cooling water volume increased to 130% (flow rate 234m 3 / h), and after 45 seconds, ΔH dropped to 0.03mm.

[0117] Thermal crown compensation: the compensation amount is updated every 20 pieces, and the roller gap is fine-tuned by +0.02mm.

[0118] S4. Tail drift and exception handling:

[0119] Tail control: Reduce speed to 3.8m / s 50 meters in advance, and reduce cooling water volume in the middle section to 80%;

[0120] Abnormal response: When the rolling force fluctuation is greater than 15%, insert a gradual transition material (4.0→3.7→3.5mm); when the iron oxide scale thickening alarm is triggered, cool rapidly.

[0121] Matters not covered in the present invention are all known technologies.

[0122] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for dynamically adjusting three-point difference during hot strip rolling, characterized in that: The method comprises the following steps: S1. Preparation before rolling and parameter initialization: Ensure that the equipment status and process parameters before rolling are optimal, laying the foundation for the subsequent rolling process; specific measures include: Roller profile matching: Select the appropriate roll profile according to the production plan. When rolling at a fast pace, choose a roll profile with large concavity to suppress thermal crown. When rolling at a slow pace, choose a roll profile with small concavity to reduce wear. Model parameter preloading: call the historical optimal parameters of the same specifications from the digital twin platform and calibrate the detection instruments; S2. Dynamic control during the threading stage. Pre-compensation of thickness and temperature is performed during the threading stage to reduce the impact of thickness fluctuations and temperature gradients in the initial stage. Specific measures include: Thickness pre-compensation: predict thickness deviation based on strip head temperature and pre-adjust roll gap; Temperature gradient suppression: reduce the amount of cooling water at the edge and stabilize the head rolling speed; S3, steady-state rolling control, real-time monitoring of the three-point difference and dynamic compensation, while taking into account the change of thermal crown to maintain thickness uniformity during steady-state rolling; specific methods include: Real-time monitoring and compensation of three-point difference: by calculating the three-point difference and responding in stages, the bending force and edge cooling flow of the operating and transmission sides are adjusted; Dynamic compensation of thermal crown: the thermal crown compensation amount is updated according to the rolling count, and the roll gap is fine-tuned through the hydraulic AGC; S4. Tail swinging and abnormality handling: Control measures are taken during the tail swinging stage to reduce tail thickness fluctuation and warpage. At the same time, transition materials are inserted in time when abnormalities occur to maintain production stability. Specific measures include: Tail stability control: reduce rolling speed, middle cooling water volume and bending roll force; Smart transition material insertion: When the abnormality is predicted to last for a long time, a gradual transition material is inserted.

2. The method for dynamically adjusting three-point difference during hot strip rolling according to claim 1, characterized in that: In step S1, the roller type is selected according to the production plan: during fast-paced rolling, the concavity is 0.12-0.15 mm to suppress thermal crown; during slow-paced rolling, the concavity is 0.05-0.08 mm to reduce wear; after changing the rollers, the hot roller material is rolled: 5-8 transition materials are rolled, the initial bending roll force is set to 80% of the reference value, and each roll is increased by 5% to full load.

3. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S1, the model parameter preloading includes: calling the historical optimal parameters of the same specifications from the digital twin platform; calibrating the detection instruments: the zero point error of the laser thickness gauge is ≤0.005mm, and the deviation of the infrared thermometer is ≤±3°C.

4. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S2, thickness pre-compensation includes: predicting thickness deviation based on strip head temperature, pre-adjusting the roll gap by 0.10-0.30 mm, wherein the roll gap is compensated by +0.05 mm for every 10°C decrease in temperature; and the bending roll force starts at 90% of the reference value and increases linearly to 100% within 10 seconds.

5. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S2, the temperature gradient suppression includes: temporarily reducing the cooling water volume at the edge to 80% of the standard value to reduce the temperature drop during strip threading; and stabilizing the rolling speed within the first 30 meters at 4.50-4.60 m / s.

6. The method for dynamically adjusting three-point difference during hot strip rolling according to claim 1, characterized in that: In step S3, the real-time monitoring and compensation of the three-point spread includes: Calculate the three-point spread: ； Among them, h L is the thickness of the operating side; hc is the thickness of the middle part; h T Transmission side thickness; △H is the three-point difference; Graded Response: When ΔH is 0.05~0.08mm, the bending roll force on the operating side increases by 6~10%; the pressure compensation on the transmission side is 0.1~0.3mm; the edge cooling flow rate increases by 10~20%; When ΔH>0.08mm, the bending roll force on the operating side increases by 10-15%; the pressure compensation on the transmission side is 0.3~0.5mm; and the edge cooling flow rate increases by 20~30%.

7. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S3, the dynamic compensation of thermal crown includes: updating the compensation amount every 18-22 rolls: Among them, C h (t) is the thermal crown compensation amount; t is the rolling time; v is the rolling speed; N is the cumulative rolling count; The roller gap is fine-tuned by hydraulic AGC, and the compensation error is ≤±0.01mm.

8. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S4, the tail stability control includes: reducing the rolling speed to 3.5-4.5 m / s 48-52 meters in advance, reducing the middle cooling water volume to 80-90%; and reducing the bending roll force stepwise to 65-75% of the baseline value to suppress tail warping.

9. The method for dynamically adjusting three-point differences during hot strip rolling according to claim 1, characterized in that: In step S4, the intelligent transition material insertion includes: when the predicted abnormal duration is greater than 5 minutes, inserting a gradual transition material, and compressing the transition section length to 14-16 meters.

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