Method for correcting rigidity of rolling mill and controlling plate shape

Abstract

The invention relates to the technical field of wide and thick plate rolling, in particular to a method for correcting the rigidity of a rolling mill and controlling the plate shape, which comprises the following steps of: acquiring rolling force values calculated in the last but one pass and the last but one pass, roll gap calculated values, actually measured rolling force values and actually measured roll gap values; calculating a pre-calculated rigidity value and an actually measured rigidity value; calculating a rolling mill rigidity deviation judgment coefficient; if the rolling mill rigidity deviation judgment coefficient exists, the rigidity compensation adjustment coefficient is corrected, and rolling force calculation is executed based on the corrected rigidity compensation adjustment coefficient; otherwise, calculation is executed according to the set rolling force. The method has the advantages that through real-time monitoring and deviation compensation of the rigidity of the rolling mill, plate shape fluctuation caused by equipment aging or working condition changes is effectively reduced; the rolling force deviation of the last pass is stably controlled within 60 tons, and the plate shape qualification rate is increased; and by introducing a rigidity fluctuation identification and compensation mechanism, instability factors in the rolling process are reduced.

Description

Technical Field

[0001] This invention relates to the field of heavy plate rolling technology, and in particular to a method for controlling plate shape by correcting the stiffness of a rolling mill. Background Technology

[0002] In thermomechanically controlled process (TMCP) steel plate production, rationally setting rolling parameters to optimize the distribution of the finishing mill's reduction load (including rolling force and reduction rate) and reduce uneven deformation during rolling are key technical measures for controlling steel plate shape and ensuring plate quality. From the model calculation of roll gap load distribution to the dynamic adjustment of the rolling process, everything depends on the accurate calculation and control of parameters such as rolling force, roll gap, and reduction. If the calculation accuracy is insufficient, plate shape control will lose stability.

[0003] In recent years, with the increasing service life of equipment, the precision of key components of rolling mills has gradually declined, leading to a series of production and equipment problems that seriously affect the shape of steel plates and the stability of the rolling process. Specifically, this manifests as various shape defects, such as: Common wave shape defects include single-sided waves, double-sided waves, intermediate waves, and zigzag waves; Composite waves, especially composite deformations that are difficult to meet the requirements of laminar flow cooling processes.

[0004] In actual shape control tests, it was found that the mill stiffness fluctuated significantly in the last two rolling passes. Mill stiffness is an important indicator of mill accuracy, and its fluctuation directly affects the accuracy of the model calculations of rolling force and roll gap, thereby changing the residual stress distribution inside the steel plate, causing instability in the rolling process, leading to a decline in product quality or even scrapping.

[0005] Traditional strip shape control models typically calculate rolling force setpoints based on factors such as incoming material thickness, steel grade, roll thermal crown, roll wear, and actual strip shape feedback, treating mill stiffness as a fixed constant and only making minor adjustments to subsequent billets through adaptive functions. This rigid approach is no longer suitable for current equipment conditions and production environments. Once stiffness changes, the rolling force setpoint becomes inaccurate, affecting the actual input of bending force and roll overlap, leading to deteriorated strip shape control, increased rolling risk, decreased efficiency, and increased scrap and defect rates.

[0006] Some plate shape control methods have been disclosed in the prior art, for example: The patent, with publication number CN102284507A and titled "A method for controlling the shape of a rolling mill for high-strength thin-gauge steel plates," improves the shape of the plate by controlling the convexity of the steel plate, but does not address the control strategy when the stiffness of the rolling mill changes. The patent, with publication number CN103302106A and titled "Method and Control Method for Improving the Straightness of Thick Steel Plates During Rolling," is applicable to steel plates with a thickness ≥ 40 mm by limiting parameters such as bite speed, rolling speed, acceleration, and final rolling force. However, it still does not consider the influence of mill stiffness fluctuations. The patent, published under CN104942018A and titled "A method for controlling the shape of rolling mill plates for thick-gauge high-grade marine engineering steel," is applicable to steel plates with a thickness of 50-60mm by constraining parameters such as final rolling reduction, maximum torque, and bending roll force. However, it does not compensate for changes in rolling mill stiffness.

[0007] Therefore, there is a lack of existing technologies that can effectively identify and compensate for changes in mill stiffness, improve the accuracy of strip shape control and rolling stability, especially for aging equipment with frequent stiffness fluctuations or high-precision strip shape control requirements. Summary of the Invention

[0008] The purpose of this invention is to provide a method for correcting the shape control of rolling mill stiffness, in order to solve the problems of inaccurate model settings and reduced shape quality caused by fluctuations in rolling mill stiffness in existing shape control technologies. This invention collects rolling process data in real time, calculates the rolling mill stiffness deviation judgment coefficient, and dynamically identifies stiffness changes. Based on the judgment results, a stiffness compensation mechanism is automatically introduced to correct key parameters such as rolling force, bending roll force, and roll overlap, thereby compensating for stiffness fluctuations caused by equipment aging and changes in operating conditions. It aims to improve the accuracy of shape control and rolling stability, reduce shape defects and production accidents, and is applicable to the rolling process of high-quality plates such as thin and wide steel plates, thereby improving product quality and production efficiency.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A method for correcting the shape of a rolling mill to control stiffness includes: S1. Collect the rolling force values ​​calculated from the penultimate and penultimate passes. , and roll gap calculation value , and measured rolling force value , and measured roll gap value , , used to calculate mill stiffness deviation; S2. Calculate the pre-calculated stiffness value. and measured stiffness values It is used to characterize the theoretical stiffness and actual stiffness of the rolling mill during the rolling process; S3. Calculate the mill stiffness deviation judgment coefficient. This is used to determine whether the stiffness of the rolling mill has changed; S4. If the mill stiffness deviation determination coefficient The stiffness compensation adjustment coefficient is corrected, and the rolling force is calculated based on the corrected stiffness compensation adjustment coefficient; otherwise, the calculation is performed according to the set rolling force.

[0010] In S2, the pre-calculated stiffness value The calculation formula is: ①; Measured stiffness value The calculation formula is: ②; in: This indicates the pre-calculated stiffness value, in kN / mm. This indicates the rolling force value calculated for the penultimate pass, in kN. This represents the calculated value of the roll gap for the penultimate pass, in mm. This indicates the rolling force value calculated for the penultimate pass, in kN. This represents the calculated value of the second-to-last roll gap, in mm. This represents the measured stiffness value, in kN / mm. This represents the measured rolling force value for the penultimate pass, in kN. This represents the measured roll gap value for the penultimate pass, in mm. This represents the measured rolling force value of the penultimate pass, in kN. This indicates the measured roll gap value from the penultimate pass, in mm.

[0011] In S3, the determination coefficient for mill stiffness deviation The calculation formula is: ③; in: This indicates the inherent stiffness of the rolling mill, expressed in kN / mm.

[0012] After changing rolls on the finishing mill, the stand is calibrated and its stiffness is measured. The stiffness fluctuation before and after the roll change is assessed based on the measurement results. Then calculate according to the set rolling force; if Then, stiffness compensation calculations are performed.

[0013] After the support rolls of the finishing mill are changed and the size of the stepped shims is altered, a mill stand bounce test and stiffness measurement are performed. If the measured stand stiffness is less than 8300 KN / mm, the calculation is performed with a stiffness compensation adjustment coefficient of 1.07~1.17; if the stand stiffness is greater than or equal to 8300 KN / mm, the calculation is performed with a stiffness compensation adjustment coefficient of 0.9~1.0.

[0014] It also includes calculating the rolled thickness based on the thickness equation, which is: ④; in: This indicates the unloaded roll gap value, in mm. This indicates the unloaded roll gap value, in meters (m). This indicates the effect of the bending roller force on the exit thickness, in mm. This indicates the zero-position compensation amount for the roll gap, in mm. This indicates the change in oil film thickness, expressed in mm. The formula for calculating the unloaded roll gap value is: ⑤; in: This represents the stiffness coefficient, with units of kN / mm. This indicates the zeroing rolling force, expressed in kN. This represents the calculated value of the current rolling force, in kN. This represents the mill stiffness width correction factor; This indicates the length of the roll body, in mm. This indicates the width of the board, in mm. The effect of bending roll force on exit thickness The calculation formula is: ⑥; This represents the bending force of the roller, expressed in kN. This represents the coefficient of influence of bending roller force on thickness, expressed in kN / mm.

[0015] It also includes calculating the rolling force based on the rolling force equation. The rolling force equation is: ⑦; in: Indicates the stress coefficient; This indicates the average width of the rolled piece, in mm. This represents the resistance to deformation, expressed in kg / mm². Indicates the contact arc length, in mm; This represents the rolling force function.

[0016] In S4, the stiffness compensation adjustment factor is: ⑧.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. By real-time monitoring and deviation compensation of the rolling mill stiffness, the plate shape fluctuation caused by equipment aging or changes in working conditions is effectively reduced; it is especially suitable for rolling thin and wide steel plates of 6~14mm, so that the rolling force deviation of the last pass is stably controlled within 600KN, thereby improving the plate shape qualification rate. 2. The introduction of stiffness fluctuation identification and compensation mechanism significantly reduces instability factors in the rolling process; it can reduce production accidents such as scraping frames and jamming steel caused by poor plate shape, and reduce the accident rate. 3. By real-time correction of rolling force, bending roll force and roll overlap, the quality of the sheet shape was greatly improved, and defects such as composite waves and single-sided waves were reduced; the scrap rate and defect rate were significantly reduced, the sheet shape qualification rate was increased by 10.56%, and the yield and economic benefits were improved. 4. Not only is it suitable for conventional rolling conditions, but it can also effectively cope with stiffness fluctuations caused by equipment changes such as roll changing, support roll changing, and stepped shim adjustment; the system dynamically adjusts the compensation coefficient according to the measured data to adapt to different steel grades, specifications and process conditions. 5. Reduce downtime for adjustments due to plate shape issues, improve mill operating rate, and increase rolling rhythm and output by optimizing rolling parameter allocation; a stable rolling process reduces abnormal loads and impacts on equipment, which helps extend the service life of key components such as rolls and bearings; and reduces equipment maintenance frequency and costs. 6. By integrating with the background data analysis system (PDA), real-time monitoring, diagnosis, and adaptive adjustment of the rolling process can be achieved, providing a reliable data foundation and control strategy for the rolling and digital twin systems. Detailed Implementation

[0018] The present invention will now be described in detail, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0019] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0020] Example 1: Mill stiffness gradually decreases with increasing equipment service life. The Power Process Analysis (PDA) system, based on the reasonable distribution of rolling load in the finishing mill, fully considers the impact of rolling force, reduction, and other factors on uneven deformation of the steel plate to ensure uniform rolling deformation. The system calculates and corrects rolling force and roll gap locking values ​​using function models, and detects mill stiffness fluctuations. This is mainly achieved by compensating for deviations in the fully hydraulic automatic thickness control (AGC) system and adjusting the finishing mill's CVC value and bending roll force control to achieve uniformity in plate shape and micro-deformation in the width direction. Furthermore, a mill stiffness deviation judgment coefficient is introduced. To identify fluctuations in mill stiffness.

[0021] A method for controlling plate shape by correcting the stiffness of a rolling mill, specifically including: S1. Calculate the mill stiffness deviation determination coefficient X; During one rolling cycle, the following data is collected: inherent stiffness of rolling mill ; Rolling force value calculated for the penultimate pass KN; Calculated value of the last pass roll gap mm; Rolling force value calculated for the penultimate pass 0KN; Calculated value of the second to last roll gap mm; Measured rolling force value of the penultimate pass 0KN; The measured roll gap value of the penultimate pass mm; The measured rolling force value of the penultimate pass 0KN; The second to last measured roll gap value mm; Calculate the pre-calculated stiffness value : KN / mm; Calculate the measured stiffness value : KN / mm; Calculate the determination coefficient for rolling mill stiffness deviation : ; because The system determines that the mill stiffness has fluctuated significantly and that a compensation value needs to be introduced to correct the stiffness.

[0022] S2. Calculate the rolled thickness according to the thickness equation; Thickness equation; ①; Suppose the parameters for a certain pass are as follows: Unloaded roller gap value mm.

[0023] Unloaded roller gap value The calculation formula is: ②; in: This indicates the zeroing rolling force, expressed in kN. Stiffness coefficient KN / mm; Zero rolling force KN; Rolling mill stiffness width correction factor ; Roll body length mm; board width mm; Substitute into formula ②: mm.

[0024] The effect of bending roll force on exit thickness : mm; in: Bending roller force KN; The influence coefficient of bending roller force on thickness mm.

[0025] Roll gap zero position compensation amount : mm; in: Roll gap zero constant mm; thermal expansion mm Wear mm.

[0026] Oil film thickness change : mm; in: Pressure coefficient of oil film thickness ; Oil film reference thickness mm; Combining the thickness equation: Thickness equation; mm.

[0027] S3. Calculate the rolling force; The rolling force equation is: ③; in: Stress coefficient ; Average width of rolled piece mm; Deformation resistance kg / mm2; Contact arc length mm; Rolling force function ; Substitute into formula ③: KN.

[0028] S4, Plate Shape Control Calculation; S41. Calculation of the proportional coefficient for adjusting the shape of the plate by the change in rolling force; ④; in: This represents the proportional coefficient for plate shape control; This represents the coefficient indicating the effect of rolling pressure changes on the roll gap. This represents the influence coefficient of the plate shape control method on the roll gap. The strip shape control ratio coefficient represents the amount of control measures required to compensate for changes in unit rolling force.

[0029] For example, in a certain finishing rolling pass of a medium-thick plate, with n=3 (i.e., the plate shape is described by 4 characteristic components), the measured data are as follows: Influence coefficient of rolling force variation: =[0.2,0.5,-0.3,0.1]; Influence coefficient of bending roller control method: =[0.1,0.6,-0.2,0.05]; Step a: Calculate the numerator ∑ ; The numerator is calculated as follows: (0.2 × 0.1) + (0.5 × 0.6) + (-0.3 × -0.2) + (0.1 × 0.05) = 0.02 + 0.3 + 0.06 + 0.005 = 0.385. Step b: Calculate the denominator ∑ The square of; Denominator = 0.1*0.1 + 0.6*0.6 + (-0.2)*(-0.2) + 0.05*0.05 = 0.01 + 0.36 + 0.04 + 0.0025 = 0.4125; Step c: Calculation ; =0.385 / 0.4125≈0.933; ≈0.933 means that when the rolling force changes by 1 unit, approximately 0.933 units of bending roll adjustment are required to offset its effect on the plate shape.

[0030] if A value >0 indicates that the change in rolling force is consistent with the direction of the effect of roll bending control on the sheet shape, and the control measures can effectively compensate for rolling force disturbances; if If the value is less than 0, the effect is in the opposite direction and requires reverse adjustment. S42, Calculation formula for actual roll gap crown; ⑤; in: Indicates the actual roll gap crown, in mm; This indicates the flexural deformation displacement on the right side of the work roll, in mm, with a value of 0.05 mm. This indicates the initial crown on the right side of the work roll, in mm, with a value of 0.12 mm. This indicates the flexural deformation displacement on the left side of the work roll, in mm, with a value of 0.06 mm. This indicates the initial crown on the left side of the work roll, in mm, with a value of 0.11 mm. This indicates the flattening amount of the work roll, in mm, with a value of 0.03 mm. This indicates the flattening amount at the center point of the work roll, in mm, with a value of 0.02 mm. Substitute into formula ⑤: ; S43, Calculation formula for reference value of bending roller control; ⑥; in: ∆F represents the reference value for bending roller control, in kN; This represents the rolling force compensation gain, with a value of 1.1. Indicates the rolling force plate shape coefficient; Indicates the bending roller force plate shape coefficient; The value is 0.05; P represents the actual value of the rolling force, in tons of force, and is 12000 kN. F represents the actual value of the bending roller force, in tons of force, and is 3000 kN. This indicates the rolling force lock value, in tons of force, with a value of 11500 kN; This indicates the locking value of the bending roller force, in tons of force, with a value of 2800 kN. Substitute into formula ⑥: .

[0031] S44. Calculation formula for thermal expansion of rolling mill rolls: ⑦; i represents the i-th segment along the axis, i=1,2,...; j represents the j-th radial segment; This indicates the initial diameter of the roll, in mm, with a value of 800 mm. This represents the coefficient of linear expansion, with a value of [value missing]. ; This represents the temperature of the i-th and j-th unit cells, in C, with a value of 150 C. The initial temperature of the i-th and j-th unit cells is in C, and the value is 20 C. N is the number of layers of the radial cylinder, and its value is 10. This represents the amount of thermal expansion, expressed in mm. Substitute into formula ⑦: .

[0032] S45. Calculation formula for roll wear; ⑧; in: This represents the amount of roll wear calculated in the kth time for the i-th segment, in mm; i represents the i-th segment along the axis; k represents the kth calculation; This represents the load segment weighting correction factor, with a value of 0.05 mm / (mKN); This represents the length rolled between the (k-1)th and kth calculations, in meters, with a value of 5000m. The unit length load of the i-th segment on the roll, in KN / mm, is taken as 100KN / mm; Substitute into formula ⑧: .

[0033] S5. Control Method: S51. After changing rolls on the finishing mill, the stand is calibrated and its stiffness is measured. Based on the measurement results, the magnitude of stiffness fluctuation before and after the roll change is determined. If the mill stiffness deviation determination coefficient X < 0.1, the mill stand is directly calculated based on the set rolling force; If the mill stiffness deviation judgment coefficient X ≥ 0.1, adjust the stiffness compensation adjustment coefficient (please provide an example of how to adjust the stiffness compensation adjustment coefficient). S52. When the size of the stepped shims changes after the support rolls are replaced in the finishing mill, a frame bounce test and stiffness measurement shall be performed. If the frame stiffness is <8300KN / mm, the calculation shall be performed according to the stiffness compensation adjustment factor of 1.07~1.17; If the frame stiffness is ≥8300KN / mm, the frame is calculated with a stiffness compensation adjustment factor of 0.9~1.0.

[0034] This invention introduces the calculation and judgment of the mill stiffness deviation judgment coefficient X, which can improve the shape control accuracy of 6-14mm thin steel plates (within 600KN of the last rolling deviation), reduce the probability of finishing frame scrap and defective products caused by poor plate shape, and improve the plate shape qualification rate. While improving quality, it greatly reduces the probability of accidents and improves rolling stability.

[0035] Example 2 In this embodiment, a method for correcting the stiffness of the rolling mill and controlling the plate shape is the same as in Embodiment 1, but with the addition of a control process.

[0036] After changing rolls on a finishing mill, the mill stand was calibrated and its stiffness was measured. The relevant data are as follows: (1 ton of force / mm = 10 kN / mm) Inherent stiffness of the rolling mill before roll change (Obtained through historical data or calibration); Inherent stiffness of the rolling mill after roll change (Obtained through calibration measurement); Current inherent stiffness reference value of rolling mill KN / mm (take recent typical value).

[0037] Step 1: Collect the rolling data for the two most recent passes after the roll change, as shown in the table below; Step 2: Calculate the pre-calculated stiffness value: .

[0038] Step 3: Calculate the measured stiffness value: .

[0039] Step 4: Calculate the stiffness deviation determination coefficient: ; Since the mill stiffness deviation determination coefficient X=0<0.1, the system determines that the stiffness has not fluctuated significantly this time, but it is still necessary to compare whether the change in inherent stiffness before and after the roll change affects the model.

[0040] Step 5: Determine whether to enable stiffness compensation; Although the mill stiffness deviation determination coefficient X=0, the change in inherent stiffness before and after the roll change is as follows: ; Rate of change: ; According to the process settings, compensation needs to be initiated when the rate of change of inherent stiffness exceeds 3%. Therefore, the system still determines that stiffness compensation is required.

[0041] Step 6: Determine the stiffness compensation adjustment coefficient; The formula for calculating the compensation adjustment coefficient Kc is as follows: ; in: The gain compensation factor is set to 0.8; This represents the change in stiffness; Indicates the stiffness before roller replacement; Substituting, we get: .

[0042] Step 7: Perform the calculation of the rolling force after compensation. Original rolling force The ton force, after compensation, is: .

[0043] This invention effectively reduces plate shape fluctuations caused by equipment aging or changes in operating conditions through real-time monitoring and deviation compensation of rolling mill stiffness. It is particularly suitable for rolling thin steel plates of 6-14mm width, ensuring that the final rolling force deviation is stably controlled within 600KN, thus improving the plate shape qualification rate. The introduction of a stiffness fluctuation identification and compensation mechanism significantly reduces instability factors during the rolling process, reducing production accidents such as scraping and jamming caused by poor plate shape, thereby lowering the accident rate. By real-time correction of rolling force, bending roll force, and roll overlap, it significantly improves plate shape quality and reduces defects such as composite waves and single-sided waves. The scrap rate and defect rate are significantly reduced, improving yield and economic efficiency. It is not only applicable to conventional rolling. Under various operating conditions, the system can effectively address stiffness fluctuations caused by equipment changes such as roll changing, support roll changing, and stepped shim adjustment. It dynamically adjusts the compensation coefficient based on measured data to adapt to different steel grades, specifications, and process conditions. This reduces downtime for adjustments due to plate shape issues, improves mill operating rates, and enhances rolling rhythm and output by optimizing rolling parameter allocation. A stable rolling process reduces abnormal loads and impacts on equipment, helping to extend the service life of key components such as rolls and bearings. It also reduces equipment maintenance frequency and costs. Combined with a background data analysis system (PDA), it enables real-time monitoring, diagnosis, and adaptive adjustment of the rolling process, providing a reliable data foundation and control strategy for the rolling and digital twin systems.

Claims

1. A method for controlling plate shape by correcting the stiffness of a rolling mill, characterized in that, include: S1. Collect the rolling force values ​​calculated from the penultimate and penultimate passes. , and roll gap calculation value , and measured rolling force value , and measured roll gap value , , used to calculate mill stiffness deviation; S2. Calculate the pre-calculated stiffness value. and measured stiffness values It is used to characterize the theoretical stiffness and actual stiffness of the rolling mill during the rolling process; S3. Calculate the mill stiffness deviation judgment coefficient. This is used to determine whether the stiffness of the rolling mill has changed; S4, if the mill stiffness deviation determination coefficient The stiffness compensation adjustment coefficient is corrected, and the rolling force is calculated based on the corrected stiffness compensation adjustment coefficient; otherwise, the calculation is performed according to the set rolling force.

2. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, In S2, the pre-calculated stiffness value The calculation formula is: ①； The measured stiffness value The calculation formula is: ②； in: This indicates the pre-calculated stiffness value, in kN / mm. This indicates the rolling force value calculated for the penultimate pass, in kN. This represents the calculated value of the roll gap for the penultimate pass, in mm. This indicates the rolling force value calculated for the penultimate pass, in kN. This represents the calculated value of the second-to-last roll gap, in mm. This represents the measured stiffness value, in kN / mm. This represents the measured rolling force value for the penultimate pass, in kN. This represents the measured roll gap value for the penultimate pass, in mm. This represents the measured rolling force value of the penultimate pass, in kN. This indicates the measured roll gap value from the penultimate pass, in mm.

3. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, In S3, the rolling mill stiffness deviation determination coefficient The calculation formula is: ③； in: This indicates the inherent stiffness of the rolling mill, expressed in kN / mm.

4. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, After changing rolls on the finishing mill, the stand is calibrated and its stiffness is measured. The stiffness fluctuation before and after the roll change is assessed based on the measurement results. Then calculate according to the set rolling force; if Then, stiffness compensation calculations are performed.

5. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, After the support rolls of the finishing mill are changed and the size of the stepped shims is altered, a mill stand bounce test and stiffness measurement are performed. If the measured stand stiffness is less than 8300 KN / mm, the calculation is performed with a stiffness compensation adjustment coefficient of 1.07~1.17; if the stand stiffness is greater than or equal to 8300 KN / mm, the calculation is performed with a stiffness compensation adjustment coefficient of 0.9~1.

0.

6. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, It also includes calculating the rolled thickness based on the thickness equation, which is: ④； in: This indicates the unloaded roll gap value, in mm. This indicates the unloaded roll gap value, in meters (m). This indicates the effect of the bending roller force on the exit thickness, in mm. This indicates the zero-position compensation amount for the roll gap, in mm. This indicates the change in oil film thickness, expressed in mm. The formula for calculating the unloaded roll gap value is: ⑤； in: This represents the stiffness coefficient, with units of kN / mm. This indicates the zeroing rolling force, expressed in kN. This represents the calculated value of the current rolling force, in kN. This represents the mill stiffness width correction factor; This indicates the length of the roll body, in mm. This indicates the width of the board, in mm. The effect of bending roll force on exit thickness The calculation formula is: ⑥； This represents the bending force of the roller, expressed in kN. This represents the coefficient of influence of bending roller force on thickness, expressed in kN / mm.

7. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, It also includes calculating the rolling force based on the rolling force equation. The rolling force equation is: ⑦； in: Indicates the stress coefficient; This indicates the average width of the rolled piece, in mm. This represents the resistance to deformation, expressed in kg / mm². Indicates the contact arc length, in mm; This represents the rolling force function.

8. The method for controlling plate shape by correcting the stiffness of a rolling mill according to claim 1, characterized in that, In S4, the stiffness compensation adjustment coefficient is: ⑧。

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