A method for optimizing a finishing reduction system of a hot plate production line

Abstract

The present application belongs to the field of metallurgical machinery, automation and rolling technology, and particularly relates to a kind of optimization method of finishing press-down system of hot coil production line, comprising the following steps: adjusting the automatic thickness control (AGC) parameters of F5 rack in finishing mill set, including adjusting the sampling period to 1.1~1.2 times of the original value, and adjusting the single cycle adjustment coefficient to 0.4~0.6 times of the original value, to reduce the AGC adjustment rate; optimizing the AGC press-down adjustment limit of F5 rack, adjusting the maximum allowed press-down amount per unit time to 1.1~1.3 times of the original value, and adjusting the corresponding time window to 1.8~2.2 times of the original value, to constrain the press-down rate; adjusting the rolling speed adjustment coefficient of F2 to F6 rack in finishing mill set, adjusting the coefficient to 2.5~3.5 times of the original value, to improve the compensation response speed of upstream rack to tension fluctuation. The present application can significantly reduce the AGC adjustment rate, suppress the rolling force fluctuation, eliminate the risk of overshoot, improve the plate shape quality, and solve the problem of unstable tension between racks.

Description

Technical Field

[0001] This invention belongs to the fields of metallurgical machinery, automation and rolling technology, and in particular, an optimization method for a finishing rolling reduction system in a hot-rolled coil production line. Background Technology

[0002] The hot strip finishing mill is the core component of hot-rolled coil production, and its control precision directly determines the thickness accuracy, shape quality, and rolling stability of the final product. During the finishing rolling process, the F5 stand, as the rear finishing mill, plays a crucial role in the dynamic performance of its reduction system and automatic thickness control (AGC) system, decisively eliminating incoming material thickness deviations and ensuring uniform exit plate thickness. However, many existing hot-rolled coil production lines have significant deficiencies in the control of the finishing F5 stand, leading to challenges in production stability and product quality.

[0003] First, the core parameters of the pressure AGC are improperly set. The combination of an excessively short sampling period and an excessively large single adjustment coefficient leads to an overly sensitive AGC system response and an excessively fast adjustment rate. This causes frequent and significant fluctuations in rolling force, which is detrimental to the stable rolling of the finishing mill. Second, there is insufficient safety constraint on the AGC reduction adjustment amount. Large reductions in a short period of time can easily lead to "overshooting" when the system detects thickness deviations due to excessive single adjustments. This excessive reduction correction can cause drastic changes in plate shape, making it difficult for operators to intervene in time, and in severe cases, causing scrap accidents of steel plates in subsequent stands such as F6 and F7. Third, the coordinated control capability between stands is weak. The speed adjustment coefficient of the upstream stand is too low, resulting in a slow speed response. When fluctuations occur in downstream stands such as F5, the upstream stand cannot effectively compensate for the loss of tension between stands by quickly adjusting its speed, resulting in tension imbalance, further amplifying plate shape defects, and forming a vicious cycle. The problems are summarized as follows: 1. Inappropriate AGC parameter settings: The sampling period is too short and the single adjustment coefficient is too large, which causes the AGC system to be too sensitive and the rolling force to fluctuate frequently and significantly.

[0004] 2. Insufficient safety constraints: The adjustment amount of AGC is not effectively limited, which can easily lead to "overshoot" due to excessive adjustment in a single instance, causing drastic changes in plate shape and even subsequent rack waste accidents.

[0005] 3. The upstream rack speed adjustment coefficient is too low: When the downstream rack fluctuates, the upstream rack cannot compensate for the tension loss by quickly adjusting the speed, resulting in tension imbalance and amplifying plate shape defects.

[0006] The aforementioned problems are interconnected and collectively hinder the efficient and stable operation of the production line, leading to increased product dimensional deviations, poor sheet shape, and frequent production interruptions. Therefore, a systematic optimization method based on quantitative analysis is urgently needed to precisely adjust AGC parameters, reduction limits, and speed coordination, fundamentally improving the stability of the finishing rolling process. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art by proposing an optimization method for the finishing rolling reduction system of a hot-rolled coil production line. The aim is to solve the technical problems of large fluctuations in rolling force of the existing finishing F5 stand, deterioration of plate shape caused by AGC adjustment overshoot, and unstable tension between stands.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: An optimization method for a finishing rolling reduction system in a hot-rolled coil production line according to the present invention includes the following steps: Adjust the automatic thickness control (AGC) parameters of the F5 stand in the finishing mill, including adjusting the sampling period to 1.1 to 1.2 times the original value and adjusting the single-cycle adjustment coefficient to 0.4 to 0.6 times the original value, in order to reduce the AGC adjustment rate; The AGC pressing adjustment limit of the F5 rack was optimized, and the maximum allowable pressing amount per unit time was adjusted to 1.1 to 1.3 times the original value. At the same time, the corresponding time window was adjusted to 1.8 to 2.2 times the original value to constrain the pressing rate. Adjust the rolling speed adjustment coefficient of stands F2 to F6 in the finishing mill to 2.5 to 3.5 times the original value to improve the compensation response speed of the upstream stands to tension fluctuations.

[0009] As a further preferred option, the optimization method also includes a verification step to evaluate the impact of AGC adjustment on rolling force stability; from the perspective of the control principle of rolling force fluctuation: AGC adjustment rate (R AGC The faster the rolling speed, the more frequent the dynamic adjustment of the roll reduction, which easily leads to periodic fluctuations in the rolling force; conversely, the slower the rolling speed, the more frequent the dynamic adjustment of the roll reduction. AGC The slower the rolling force, the weaker the "impact source" of rolling force fluctuations. The verification method introduces a quantitative relationship of rolling force fluctuation amplitude to explain the impact of AGC adjustment on rolling force stability from the physical essence (mill electromechanical characteristics, inherent equipment fluctuations). The formula is as follows: ΔF%=α*R AGC +F base ; In the formula: ΔF% represents the rolling force fluctuation range, in %, where a smaller value indicates a smaller rolling force fluctuation. α is the rolling force fluctuation coefficient, in units of %·s, which is determined by the electromechanical characteristics of the rolling mill and is taken as 20 %·s; R AGC Adjust the speed for AGC; F base This represents the inherent basic rolling force fluctuation of the equipment, expressed in %, with a value of ±1%.

[0010] As a further preferred option, the AGC rate adjustment formula is as follows: R AGC =K adj / T sam ; In the formula: R AGC For AGC adjustment rate, the smaller the value, the smoother the adjustment and the smaller the fluctuation in rolling force; K adj T is the coefficient for single-cycle adjustment. sam The sampling period.

[0011] As a further preferred option, the AGC pressing adjustment limit of the F5 rack is optimized by introducing a pressing amount constraint formula per unit time to limit the maximum rate of AGC pressing adjustment and avoid overshoot; From the perspective of the dynamic stability principle of rolling mechanics, excessive reduction per unit time can lead to abrupt changes in rolling force (such as hysteresis of roll elastic deformation and uneven plastic flow of metal), causing thickness overshoot or equipment vibration. This can be addressed by constraining the "maximum reduction per unit time (S)". max ")" and "time window (t)" max ", so that the actual compression rate (V) press ) does not exceed the maximum allowed rate of the system (V) allow This can suppress the "peak impact" of rolling force fluctuations; the formula is as follows: V press =S max / t max ≤ V allow ; In the formula: V press The actual reduction per unit time, in mm / s; S max The maximum allowable reduction within a set time period, in mm; T max The set time window, in seconds; V allow The maximum allowable reduction per unit time for the system, in mm / s, is determined by the plate shape quality process requirements and is set to 0.1 mm / s.

[0012] As a further preferred option, the rolling speed adjustment coefficients of stands F2 to F6 in the finishing mill are adjusted, and a speed adjustment compensation formula is introduced to calculate the amount of speed adjustment required by the upstream stands to compensate for tension. Analysis based on the tension-speed coupling control principle: In a finishing mill, changes in the rolling speed of the upstream stand directly cause fluctuations in the strip tension between stands; conversely, when tension fluctuations (ΔT) occur in the downstream stand due to AGC actions or incoming material disturbances, increasing the speed adjustment coefficient (Kv) of the upstream stand can amplify the speed correction (ΔV), thereby accelerating the dynamic compensation response of the upstream stand to tension fluctuations; the formula is as follows: ΔV = Kv * ΔT; In the formula: ΔV is the speed adjustment amount of the upstream stand, in m / s; Kv is the rolling speed adjustment coefficient, in (m / s) / kN; ΔT is the tension deviation value of the oscillating stand, in kN. Beneficial effects

[0013] By extending the sampling period and reducing the adjustment amount, the AGC adjustment rate is reduced, effectively suppressing rolling force fluctuations.

[0014] By constraining the compression rate, the risk of overshoot is eliminated, and drastic changes in plate shape are avoided.

[0015] By increasing the response speed of the upstream racks, the speed compensation was increased by 3 times, which quickly stabilized the tension between racks and reduced production interruptions. Attached Figure Description

[0016] Figure 1 This is a flowchart of the optimization method proposed in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Through the optimization of this invention, combined with quantitative formulas such as AGC adjustment rate and reduction constraint, the AGC adjustment rate of F5 stand can be accurately reduced, adjustment overshoot can be avoided, tension stability between stands can be ensured, the plate shape can be reduced rapidly and crushing accidents can be reduced, and the stability of the rolling process and the quality of hot-rolled coil products can be improved.

[0019] The specific content of this invention is as follows: 1. Pressure AGC Parameter Optimization: In the pressing speed control program of the finishing mill F5 stand, two core parameters were modified: Adjust the value of "Sampling Period" from 300ms to 350ms; The coefficient for "single-cycle adjustment" is adjusted from 0.04 to 0.02; By extending the sampling period and reducing the single adjustment amount, combined with the AGC adjustment rate formula, the AGC adjustment rate of the F5 stand is reduced, thus avoiding large fluctuations in rolling force.

[0020] 2. Optimization of AGC Pressdown Adjustment Limit: In the AGC pressdown adjustment program for the F5 rack, adjust the pressdown time threshold: The original setting of "press down a maximum of 0.5mm within 3 seconds" has been changed to "press down a maximum of 0.6mm within 6 seconds". The pressing rate is constrained by the formula for the amount of pressing down per unit time to prevent AGC adjustment overshoot and avoid drastic changes in plate shape.

[0021] 3. Upstream stand speed coefficient adjustment: In the speed setpoint program of the finishing mill, optimize the speed response parameters of stands F2-F6: The rolling speed adjustment factor for stands F2 to F6 is changed from 0.1 to 0.3; By combining the speed adjustment compensation formula, the speed response sensitivity of the front frame is improved. When plate shape fluctuation occurs in a single frame, the tension change is quickly compensated to ensure the tension stability between frames.

[0022] Four specific calculation formulas: 1. Formula 1: AGC Adjustment Rate Calculation Formula The adjustment speed of the quantification AGC system is directly related to the risk of rolling force fluctuations. From the perspective of the coupling principle between control theory and the rolling process: AGC (Automatic Thickness Control) compensates for thickness deviations by adjusting the roll reduction, and its adjustment rate is determined by the sampling period (T). sam ) and single-cycle adjustment coefficient (K) adj The factors jointly determine the rolling force fluctuation. A longer sampling period results in a larger "sensing-response" interval for thickness deviations, leading to smoother adjustments; a smaller single adjustment coefficient results in a smaller adjustment amplitude per cycle, weakening the "impact source" of rolling force fluctuations. The combined effect of these two factors reduces the AGC adjustment rate, thereby reducing rolling force fluctuations. The formula is as follows: R AGC =K adj / T sam In the formula: R AGC The AGC adjustment rate (unit: coefficient unit / ms) is calculated as follows: the smaller the value, the smoother the adjustment and the smaller the fluctuation in rolling force. K adj The single-cycle adjustment coefficient (unitless) was 0.04 before optimization and 0.02 after optimization. T samThe sampling period (unit: ms) was 300ms before optimization and 350ms after optimization.

[0023] Calculation comparison: Before optimization: R AGC =0.04 / 300=0.00013; After optimization: R AGC =0.02 / 350=0.000057: The optimized adjustment rate is reduced by approximately 57%, effectively reducing adjustments caused by fluctuations in rolling force.

[0024] 2. Formula 2: Formula for Rolling Force Fluctuation Amplitude To evaluate the stability of rolling force after AGC adjustment, the statistical characteristics of rolling force fluctuation and equipment characteristics are analyzed: rolling force fluctuation is jointly determined by the AGC adjustment rate (dynamic factor) and the inherent characteristics of the equipment (static factor). The formula introduces the rolling force fluctuation amplitude (ΔF%) to quantify the optimization effect. The formula is as follows: ΔF%=α*R AGC +F base In the formula: ΔF% represents the rolling force fluctuation range (unit: %). α is the rolling force fluctuation coefficient (unit: %·s), which is determined by the electromechanical characteristics of the rolling mill. In this example, the value is taken as 20 %·s. R AGC Adjust the AGC rate (calculated using Formula 1); F base The value represents the inherent basic rolling force fluctuation of the equipment (unit: %), which is ±1% in this example.

[0025] The calculations and comparisons are as follows: Before optimization: ΔF% (before) = 20 × 0.133 + 1 ≈ ±3.66% (in actual production, due to the superposition of interference, it can reach ±8%). After optimization: ΔF% (after) = 20 × 0.057 + 1 ≈ ±2.14% (in actual production, it can be stabilized at ±3%, which is basically consistent with the experimental verification effect); This formula verifies the effectiveness of parameter optimization in suppressing rolling force fluctuations.

[0026] 3. Formula 3: Formula for constraint on reduction per unit time This is used to limit the maximum rate of AGC reduction on the F5 stand to prevent overshoot. From the perspective of rolling mechanics and dynamic stability principles, excessive reduction per unit time during the rolling mill reduction process can cause sudden changes in rolling force (such as hysteresis of roll elastic deformation and uneven metal plastic flow), leading to thickness overshoot or equipment vibration. By constraining the maximum reduction per unit time (S... max) and time window (t) max ), making the actual compression rate (V press ) not exceeding the allowable rate (V allow This can suppress the "peak impact" of rolling force fluctuations. The formula is as follows: V press =S max / t max ≤ V allow In the formula: V press This represents the actual reduction per unit time (unit: mm / s). S max The maximum allowable reduction within a set time (unit: mm) was 0.5 mm before optimization and 0.6 mm after optimization. T max The set time window (unit: seconds) was 3 seconds before optimization and 6 seconds after optimization. V allow The maximum allowable reduction per unit time (unit: mm / s) is determined by the plate shape quality process requirements; in this example, the value is 0.1 mm / s.

[0027] The calculations and comparisons are as follows: Before optimization: V press (Front) = 30.5 ≈ 0.167 mm / s > 0.1 mm / s (Exceeds the allowable value, there is a risk of overshoot); After optimization: V press (After) = 60.6 = 0.1 mm / s ≤ Vallow (meets process requirements and completely eliminates the risk of overshoot).

[0028] 4. Formula 4: Speed ​​Adjustment Compensation Formula This technology is used to improve the response speed of F2-F6 stands to tension fluctuations. Analysis based on the tension-speed coupling principle in continuous rolling mills reveals that thickness fluctuations in downstream stands (such as F5) affect upstream stands (F2-F6) through tension transmission. Increasing the rolling speed adjustment coefficient of upstream stands can accelerate their "sensing-adjustment" response to tension changes, compensating for tension fluctuations in advance and preventing the accumulation of thickness deviations.

[0029] ΔV=Kv*ΔT In the formula: ΔV is the speed adjustment amount of the upstream rack (unit: m / s); Kv is the rolling speed adjustment coefficient (unit: (m / s) / kN), which is 0.1 before optimization and 0.3 after optimization; ΔT is the tension deviation value of the wave frame (unit: kN).

[0030] The calculations and comparisons are as follows (assuming tension deviation ΔT = −5kN): Before optimization: Δv(before) = 0.1 × (−5) = -0.5 m / s (insufficient compensation, large tension fluctuation); After optimization: Δv(after) = 0.3 × (−5) = -1.5 m / s (the compensation amount is increased by 3 times, which can quickly stabilize the tension). Example

[0031] This embodiment is applied to the finishing mill (stands F1-F7) of a 1450mm hot-rolled coil production line. The parameters are set using supplementary formulas, and the specific steps are as follows: 1. Pressure AGC parameter modification (based on formulas 1 and 2): The core objective of this step is to adjust the AGC rate R of the F5 rack. AGC Reduced to 0.00006 s - ¹The following measures are taken to smooth out fluctuations in rolling force.

[0032] Parameter calculation and determination: First, according to formula 1 R AGC =K adj / T sam Perform target inverse calculation. Set the target R. AGC ≤0.00006s−1, given the optimized K adj =0.02, then the required sampling period T sam ≥0.02 / 0.00006≈333ms. To allow for a margin while also considering system responsiveness, T was ultimately selected. sam =350ms.

[0033] On-site operation: Log in to the first-level automation system for finishing mill.

[0034] Navigate to the "Press Speed ​​Control" function block in the F5 rack (e.g., find the corresponding CFC or function block in Step7 or TIA Portal).

[0035] Find and modify two key parameters: change the value of the "Sampling Cycle" parameter from 300 ms to 350 ms; change the value of the "Adjustment Gain" parameter from 0.04 to 0.02.

[0036] Effect Verification: After the parameters are downloaded and applied, the rolling force trend of the F5 stand can be monitored in real time via the HMI screen. According to Formula 2, the theoretical fluctuation range ΔF%≈20×0.000057+1≈±2.14%. Actual production data should show that the rolling force fluctuation range of the F5 stand narrows from ±8% before optimization and stabilizes within ±3%.

[0037] 2. Optimization Implementation of AGC Suppression Adjustment Limit (Based on Formula 3) This step aims to reduce the unit time compression V of the F5 rack. press Constrained at a safety threshold V allow Within 0.1 mm / s, overshoot must be eliminated.

[0038] Parameter calculation and determination: According to formula 3 V press =S max / t max ≤V allow Calculate the new threshold directly. Given V allow =0.1 mm / s and the selected time window t max =6s, then the maximum reduction S max =0.1×6=0.6mm. Therefore, the new rule is determined to be "the maximum compression within 6 seconds is 0.6mm".

[0039] On-site operation: Within the same automation system, locate the "AGC Press-down Management" or "ACC (Automatic Position Control) Limit" program module for the F5 rack.

[0040] Modify the limiting parameters: change the time threshold from 3 s to 6 s; change the corresponding maximum compression limit from 0.5 mm to 0.6 mm.

[0041] Effect Verification: After modification, the new restriction rules were confirmed to be effective by checking the system logs or specific diagnostic screens. In production, operators can observe that when thickness deviations occur, the pressing action of the F5 stand becomes smoother, the sudden warping (tailing) of the plate caused by excessively rapid pressing has basically disappeared, and the steel stacking accident records at the entrance of the F6 / F7 stands should be reduced to zero.

[0042] 3. Implementation of upstream rack speed coefficient adjustment (based on formula 4) This step aims to increase the speed adjustment factor Kv of the upstream rack to 0.3, ensuring that tension fluctuations ΔT can be quickly compensated.

[0043] Parameter calculation and determination: The target is calculated back according to formula 4 ΔV=Kv*ΔT. The goal is to control the maximum tension fluctuation within ±1.5% (corresponding to the maximum tension deviation ΔT). max =±10kN), the required speed adjustment ΔV must meet the requirements of rapid compensation. Calculations show that the speed coefficient Kv must be no less than 0.28, therefore the optimized value is selected as Kv=0.3.

[0044] On-site operation: Enter the relevant procedures for "Main Speed ​​Setting" or "Loop Tension Control" of the finishing mill.

[0045] Batch modify the "Speed ​​Trim Factor" or "Tension Comp Gain" of racks F2, F3, F4, F5, and F6, uniformly changing the original value of 0.1 to 0.3. Note: This operation must ensure that the modifications are synchronized across all racks to prevent the introduction of new speed mismatches.

[0046] Effect Verification: After optimization, during the rolling process, when fluctuations occur in the F5 stand, it can be observed through the looper scanner or tension meter signal that the speed setpoint of the F2-F4 stands will immediately change more significantly (according to Formula 4, the compensation amount is increased by 3 times). The fluctuation range of the looper height is significantly reduced, and the tension between stands is more stable, thereby effectively suppressing the propagation of plate shape defects downstream.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An optimization method for the finishing rolling reduction system of a hot-rolled coil production line, characterized in that, Includes the following steps: Adjust the automatic thickness control (AGC) parameters of the F5 stand in the finishing mill, including adjusting the sampling period to 1.1 to 1.2 times the original value and adjusting the single-cycle adjustment coefficient to 0.4 to 0.6 times the original value, in order to reduce the AGC adjustment rate; The AGC pressing adjustment limit of the F5 rack was optimized, and the maximum allowable pressing amount per unit time was adjusted to 1.1 to 1.3 times the original value. At the same time, the corresponding time window was adjusted to 1.8 to 2.2 times the original value to constrain the pressing rate. Adjust the rolling speed adjustment coefficient of stands F2 to F6 in the finishing mill to 2.5 to 3.5 times the original value to improve the compensation response speed of the upstream stands to tension fluctuations.

2. The optimization method for the finishing rolling reduction system of a hot-rolled coil production line according to claim 1, characterized in that: The optimization method also includes a verification step to evaluate the impact of AGC adjustments on rolling force stability, as shown in the following formula. ΔF%=α*R AGC +F base ; In the formula: ΔF% represents the rolling force fluctuation range, in %, where a smaller value indicates a smaller rolling force fluctuation. α is the rolling force fluctuation coefficient, in units of %·s, which is determined by the electromechanical characteristics of the rolling mill and is taken as 20 %·s; R AGC Adjust the speed for AGC; F base This represents the inherent basic rolling force fluctuation of the equipment, expressed in %, with a value of ±1%.

3. The optimization method for the finishing rolling reduction system of a hot-rolled coil production line according to claim 2, characterized in that: The AGC rate adjustment formula is as follows: R AGC =K adj / T sam ; In the formula: R AGC For AGC adjustment rate, the smaller the value, the smoother the adjustment and the smaller the fluctuation in rolling force; K adj T is the coefficient for single-cycle adjustment. sam The sampling period.

4. An optimization method for a finishing rolling reduction system in a hot-rolled coil production line according to claim 1 or 3, characterized in that: The AGC (Automatic Guided Vehicle) adjustment limit for the F5 rack is optimized by introducing a unit-time adjustment constraint formula to limit the maximum rate of AGC adjustment and avoid overshoot. The formula is as follows: V press =S max / t max ≤ V allow ; In the formula: V press The actual reduction per unit time, in mm / s; S max The maximum allowable reduction within a set time period, in mm; T max The set time window, in seconds; V allow The maximum allowable reduction per unit time for the system, in mm / s, is determined by the plate shape quality process requirements and is set to 0.1 mm / s.

5. An optimization method for a finishing rolling reduction system in a hot-rolled coil production line according to claim 1 or 3, characterized in that: Adjust the rolling speed adjustment coefficients of stands F2 to F6 in the finishing mill, and introduce a speed adjustment compensation formula to calculate the speed adjustment required by the upstream stands to compensate for tension. The formula is as follows: ΔV = Kv * ΔT; In the formula: ΔV is the speed adjustment amount of the upstream stand, in m / s; Kv is the rolling speed adjustment coefficient, in (m / s) / kN; ΔT is the tension deviation value of the oscillating stand, in kN.

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