A method for improving width accuracy of hot-rolled large-width-reduced strip steel

Abstract

The present application relates to a kind of width precision promotion methods of hot-rolled large-width-reducing strip steel, the method comprises the following steps: S1, configure rough rolling each pass width, side pressure correction table;S2, rough rolling each pass vertical roll gap dynamic adjustment module;S3, rough rolling vertical roll side pressure amount dynamic correction module.The technical scheme is by dynamic adjustment large-width-reducing strip steel each pass width and side pressure amount, realizes that width control is dynamically adjusted with on-site production situation, width coefficient dynamically adjusts, the width change of each pass is promptly corrected to roll gap setting, promptly avoids the problem of subsequent pass rolling width inaccuracy, eliminates basic deviation.

Description

Technical Field

[0001] This invention relates to an improvement method, specifically a method for improving the width accuracy of hot-rolled large-width strip steel, belonging to the field of roughing width accuracy control technology in hot-rolling lines. Background Technology

[0002] A novelty search revealed that the invention, "A Method for Improving the Accuracy of Hot Roll Width Control," introduces the surface roughness of the rolls into the roughing width control and establishes a control model relationship between the width control quantity and the cumulative rolling length and the width of the rolled material. Then, based on the total thickness reduction of the rolled piece, the thickness reduction amount for each pass on each roll stand is determined. Furthermore, based on the control model's prediction of the width spread for each pass and the width reduction distribution principle, the target exit width for each pass is determined. This determines the vertical roll gap for each pass, and by controlling the vertical roll gap, the exit width of each pass is controlled, ultimately achieving control over the target width of the rolled piece in the roughing area of ​​the hot rolling mill. This invention solves the width fluctuation problem that previously occurred every time the horizontal work rolls of the roughing mill were changed, reduces operator intervention, reduces the defect rate of the rolled width, and lowers production costs.

[0003] "Optimization of Width Model Parameters and Improvement of Width Spread Self-Learning Method" focuses on the width control of a 1780mm hot-rolled stainless steel production line. This paper optimizes the width spread model parameters and improves the width self-learning method, thereby enhancing the width accuracy of the strip steel on the 1780mm production line. The paper conducts regression analysis on the width spread coefficients of the roughing mill setting for odd and even passes, thereby improving the self-learning of width spread in the finishing mill and achieving the optimization goal.

[0004] This invention primarily addresses the improvement of width accuracy for hot-rolled large-width strip steel. The main method for improving accuracy involves dynamically adjusting the load in each roughing pass. Based on the width reduction and slab width, the load is shifted forward to ensure the strip can be correctly set in the final pass, thus improving the width accuracy requirements. This differs significantly from the content of the aforementioned patents and papers. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a method for improving the width accuracy of hot-rolled large-width strip steel. This technical solution achieves dynamic adjustment of the width and side pressure of the large-width strip steel in each pass by dynamically adjusting the width control according to the on-site production conditions and the width coefficient. The width changes in each pass are promptly corrected in the roll gap setting, thus avoiding the problem of inaccurate rolling width in subsequent passes and eliminating basic deviations.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a method for improving the width accuracy of hot-rolled large-width strip steel, characterized in that the method includes the following steps:

[0007] S1. Configure the width and side pressure correction table for each pass of roughing rolling;

[0008] S2, Dynamic adjustment module for the roll gap of vertical rolls in each pass of roughing mill;

[0009] S3, Dynamic correction module for side pressure of roughing vertical roll;

[0010] Specifically as follows:

[0011] Step S1: Configure roughing width and side pressure correction tables according to strip type, width classification, and width reduction classification;

[0012] Because variations in strip width can lead to uneven stress distribution within the strip when subjected to cross-sectional forces in the width direction, the theoretically calculated dog-bone width spread deviates significantly from the natural width spread, affecting the final width control accuracy. Therefore, dynamic compensation for different widths and reduction amounts is necessary. The dynamic compensation table structure of this method is as follows:

[0013]

[0014] Table 1: Dynamic Compensation Table for Width and Side Pressure of Each Pass in Rough Rolling

[0015] The initial value of the dynamic compensation value in this table is set to 0.1. The initial value is used for the first calculation of the model. As the strip steel is continuously produced, the learning amount will be gradually corrected and eventually stabilized within a small range to meet the requirements of width control.

[0016] Step S2: Dynamic adjustment module for the roll gap of each pass in the roughing mill model;

[0017] Because it is a reversible rolling process, the vertical rolls are involved in the control during odd-numbered passes, while they are idle during even-numbered passes. Therefore, this method only considers the roll gap adjustment during odd-numbered passes.

[0018] During the production of wide strip steel, uneven stress on the cross-section can cause deviations between the actual and set strip width. If these deviations are not addressed promptly during each rolling pass, the calculated strip width will become increasingly inaccurate. When all width deviations accumulate to the target width of the final pass, the strip will become too wide to be produced. Each rolling pass involves a deviation between the set width of the model and the actual rolled width. To prevent these deviations from affecting the final rolling accuracy, they need to be eliminated in each subsequent pass. Considering measurement errors in the field and the recovery amount for different width reductions, confidence coefficients are added for different width reduction amounts. When setting the width for the next pass, no correction is made if the width deviation is less than 2mm. If the width deviation exceeds 2mm, the confidence coefficient is selected based on the width reduction amount of that pass. The final width setting method is as follows:

[0019] Next pass roll gap deviation G ij+1 =Model calculation width w ij+1 +dw ij *a;

[0020] The principle for configuring the confidence level of the deviation between the measured width and the calculated width of the strip for each pass is based on the strip width reduction. According to the production characteristics of Meigang hot rolling, the width reduction is classified and associated with the confidence level, and the confidence level is calculated and configured for strips with larger width reduction, as shown in Table 2 below.

[0021] Reduction amount Redu 25～30 30～40 40～45 45～50 >50 Confidence level a 0.4 0.55 0.75 0.8 0.9

[0022] Table 2: Strip Steel Confidence Level Configuration Table

[0023] The self-learning module in the model modifies the w in Table 1 according to the type, width, and reduction amount of the rolled strip. ij The data is used in the next setting of the corresponding pass width for this type of strip steel to ensure the elimination of basic deviations in this type of steel, and the accuracy of the model setting is getting higher and higher.

[0024] S3, Dynamic Correction Module for Side Pressure of Roughing Mill Vertical Roll, as detailed below:

[0025] The most crucial factor determining strip width is the lateral pressure of the vertical rolls. An improper distribution of lateral pressure will result in strips that are set too narrow or too wide. For large-width strips, insufficient lateral pressure usually leads to excessive width. During large-width reduction production, due to insufficient lateral pressure in the preceding passes, all width reduction work is shifted to the later stages. Although the strip becomes thinner in subsequent passes, increasing reduction efficiency, on the one hand, the thinner strip generates a greater force effect with the same reduction, making subsequent recovery uncontrollable, resulting in low actual reduction efficiency; on the other hand, due to the increased width-to-thickness ratio, a large lateral pressure can easily cause the strip to arch, leading to scrap or even damage to the vertical roll equipment, resulting in significant losses.

[0026] Therefore, the side pressure amount needs to be dynamically adjusted according to the strip width reduction, so that the side pressure is increased at the beginning of the pass and the large side pressure is reduced in the subsequent passes.

[0027] This method takes into account these characteristics of hot rolling production and dynamically adjusts the side pressure through a dynamic table.

[0028] The calculation method for the reduction of the vertical roll in hot rolling roughing mill is as follows:

[0029] eDraft i =F(W0, H0, W) 目 Temp,ED i ,RD i SPRD i DOG i Formula 1

[0030] in:

[0031] eDraft i : Pressure reduction per pass

[0032] W0 and H0: These represent the entry width and thickness of the strip in this pass, respectively.

[0033] W 目 The final target width of rough rolling

[0034] TEMP: Strip inlet temperature for this pass

[0035] ED i RD i : Roll diameter of vertical rolls and horizontal rolls

[0036] SPRD i DOG i Naturally broad, dog-bone broad

[0037] In controlling the width of the large-width strip steel, this method considers the problem of excessive subsequent reduction and width exceeding the standard width. Therefore, a dynamic optimization is performed on the algorithm, as follows:

[0038]

[0039] in:

[0040] i, j: rack number, track number;

[0041] eDraft ij The final reduction amount allocation for each rack pass;

[0042] eDraft ij0 : Initial calculation of reduction amount allocation for each rack pass;

[0043] drf ij : Dynamic reduction distribution coefficient corresponding to each rack pass.

[0044] drf ij The initial value is defined as 0.1 in Table 1, and the initial value is the same for each pass. It needs to be dynamically adjusted during subsequent production. The adjustment is calculated using the following formula:

[0045] Per-pass compression efficiency = Model set compression / Actual compression; Formula 3

[0046] Drfij = Drfij * efficiency per pass; Formula 4

[0047] As shown in step S2, the inlet and outlet widths of the strip steel at each pass are dynamically adjusted based on the model calculations for each pass. Therefore, the calculated and actual reduction for each pass will also be dynamically adjusted. The dynamic adjustment of the lateral pressure should begin during the pass calculations in the model to avoid a series of problems caused by excessive reduction in subsequent passes.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] By dynamically adjusting the width and side pressure of each pass of the large-reduction strip steel, the width control is dynamically adjusted according to the on-site production situation. The width coefficient is dynamically adjusted, and the width changes of each pass are corrected in time to the roll gap setting, which avoids the problem of inaccurate rolling width in subsequent passes, eliminates basic deviations, and improves the accuracy of model setting. The dynamic adjustment of the side pressure is achieved by calculating the distribution coefficient of the side pressure of each pass according to the differential method and using the initial value of the side pressure calculated in the early stage, so that the distribution of the side pressure of each pass is more reasonable and the transition is more in line with production. Adjusting the side pressure coefficient of the previous pass of the large-reduction strip steel can effectively avoid the problem of excessive width due to excessive reduction of the strip in subsequent passes. Attached Figure Description

[0050] Figure 1 Flowchart for vertical and horizontal roll rolling processes;

[0051] Figure 2 This is a flowchart for adjusting the roll gap. Detailed Implementation

[0052] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0053] Example 1: See Figure 1 Meigang has four main width control devices in the hot rolling roughing zone: E1, R1, E2, and R2. E1 and E2 are vertical roll control devices, while R1 and R2 are horizontal roll control devices. The width of the hot rolling mill is controlled by E1 and E2 for dog-bone control, and R1 and R2 for width spread control.

[0054] Bi: Delivery width of RM (mm)

[0055] BEi:Delivery width of edger(mm)

[0056] Bi-1: Entry width of edger (mm)

[0057] hi-1:Entry thickness of edger(mm)

[0058] hi:Delivery thickness of RM(mm)

[0059] Existing hot rolling processes all utilize reversible mills. From the perspectives of on-site rolling demand, rhythm control, and cost control, the rolling strategy for two stands is generally 3+3 or 3+5. After production using this rolling strategy, the rolling width range of hot-rolled steel has been significantly improved compared to the previous irreversible rolling, enabling the expansion of hot-rolled products. However, this also leads to the phenomenon of excessively wide stripe steel with large width reduction. The main reason for this phenomenon is that with the increase in rolling passes, the load distribution and width-to-thickness ratio of each pass are prone to change. The model cannot control the changes in each pass as a whole, and all width reduction is cumulatively shifted to the later passes, resulting in excessive side pressure in the later passes, making width reduction impossible.

[0060] To achieve the above objectives, the technical solution of this method is as follows: a method for improving the width accuracy of hot-rolled large-width strip steel, characterized in that the method includes the following steps:

[0061] S1. Configure the width and side pressure correction table for each pass of roughing rolling;

[0062] S2, Dynamic adjustment module for the roll gap of vertical rolls in each pass of roughing mill;

[0063] S3, Dynamic correction module for side pressure of roughing vertical roll. Detailed implementation method:

[0065] Step S1: Configure roughing width and side pressure correction tables according to strip type, width classification, and width reduction classification.

[0066] Because variations in strip width can lead to uneven stress distribution within the strip when subjected to cross-sectional forces in the width direction, the theoretically calculated dog-bone width spread deviates significantly from the natural width spread, affecting the final width control accuracy. Therefore, dynamic compensation for different widths and reduction amounts is necessary. The dynamic compensation table structure of this method is as follows:

[0067]

[0068] Table 1: Dynamic Compensation Table for Width and Side Pressure of Each Pass in Rough Rolling

[0069] The initial value of the dynamic compensation value in this table is set to 0.1. The initial value is used for the first calculation of the model. As the strip steel is continuously produced, the learning amount will be gradually corrected and eventually stabilized within a small range to meet the requirements of width control.

[0070] Step S2: Dynamic adjustment module for the roll gap of each pass in the roughing mill model.

[0071] Because it is a reversible rolling process, the vertical rolls are involved in the control during odd-numbered passes, while they are idle during even-numbered passes. Therefore, this method only considers the roll gap adjustment during odd-numbered passes.

[0072] During the production of wide strip steel, uneven stress on the cross-section can cause deviations between the actual and set strip width. If these deviations are not addressed promptly during each rolling pass, the calculated strip width will become increasingly inaccurate. When all width deviations accumulate to the target width of the final pass, the strip will become too wide to be produced. Figure 2 The flowchart for roll gap adjustment illustrates the deviation between the set width of a model and the actual rolling width during each strip rolling pass. To prevent width deviations from affecting the final rolling accuracy, they need to be eliminated in each subsequent pass. Considering the measurement error of the width on-site and the recovery amount for different width reductions, confidence coefficients are added for different width reduction amounts. When setting the width for the next pass, no correction is made if the width deviation is less than 2mm. If the width deviation exceeds 2mm, the confidence coefficient is selected based on the width reduction amount of that pass. The final width setting method is as follows:

[0073] Next pass roll gap deviation G ij+1 =Model calculation width w ij+1 +dw ij *a;

[0074] The principle for configuring the confidence level of the deviation between the measured width and the calculated width of the strip for each pass is based on the strip width reduction. According to the production characteristics of Meigang hot rolling, the width reduction is classified and associated with the confidence level, and the confidence level is calculated and configured for strips with larger width reduction, as shown in Table 2 below.

[0075]

[0076]

[0077] Table 2: Strip Steel Confidence Level Configuration Table

[0078] The self-learning module in the model modifies the w in Table 1 according to the type, width, and reduction amount of the rolled strip. ij The data is used in the next setting of the corresponding pass width for this type of strip steel to ensure the elimination of basic deviations in this type of steel, and the accuracy of the model setting is getting higher and higher.

[0079] S3, Dynamic Correction Module for Side Pressure of Roughing Mill Vertical Roll

[0080] The most crucial factor determining strip width is the lateral pressure of the vertical rolls. An improper distribution of lateral pressure will result in strips that are set too narrow or too wide. For large-width strips, insufficient lateral pressure usually leads to excessive width. During large-width reduction production, due to insufficient lateral pressure in the preceding passes, all width reduction work is shifted to the later stages. Although the strip becomes thinner in subsequent passes, increasing reduction efficiency, on the one hand, the thinner strip generates a greater force effect with the same reduction, making subsequent recovery uncontrollable, resulting in low actual reduction efficiency; on the other hand, due to the increased width-to-thickness ratio, a large lateral pressure can easily cause the strip to arch, leading to scrap or even damage to the vertical roll equipment, resulting in significant losses.

[0081] Therefore, the side pressure amount needs to be dynamically adjusted according to the strip width reduction, so that the side pressure is increased at the beginning of the pass and the large side pressure is reduced in the subsequent passes.

[0082] This method takes into account these characteristics of hot rolling production and dynamically adjusts the side pressure through a dynamic table.

[0083] The calculation method for the reduction of the vertical roll in hot rolling roughing mill is as follows:

[0084] eDraft i =F(W0, H0, W) 目 Temp,ED i ,RD i SPRD i DOG i Formula 1

[0085] in:

[0086] eDraft i : Pressure reduction per pass

[0087] W0 and H0: These represent the entry width and thickness of the strip in this pass, respectively.

[0088] W 目 The final target width of rough rolling

[0089] TEMP: Strip inlet temperature for this pass

[0090] ED i RD i : Roll diameter of vertical rolls and horizontal rolls

[0091] SPRD i DOG i Naturally broad, dog-bone broad

[0092] In controlling the width of the large-width strip steel, this method considers the problem of excessive subsequent reduction and width exceeding the standard width. Therefore, a dynamic optimization is performed on the algorithm, as follows:

[0093]

[0094] in:

[0095] i, j: rack number, track number;

[0096] eDraft ij The final reduction amount allocation for each rack pass;

[0097] eDraft ij0 : Initial calculation of reduction amount allocation for each rack pass;

[0098] drf ij : Dynamic reduction distribution coefficient corresponding to each rack pass.

[0099] drf ij The initial value is defined as 0.1 in Table 1, and the initial value is the same for each pass. It needs to be dynamically adjusted during subsequent production. The adjustment is calculated using the following formula:

[0100] Per-pass compression efficiency = Model set compression / Actual compression; Formula 3

[0101] Drfij = Drfij * efficiency per pass; Formula 4

[0102] As shown in step S2, the inlet and outlet widths of the strip steel at each pass are dynamically adjusted based on the model calculations for each pass. Therefore, the calculated and actual reduction for each pass will also be dynamically adjusted. The dynamic adjustment of the lateral pressure should begin during the pass calculations in the model to avoid a series of problems caused by excessive reduction in subsequent passes.

[0103] Beneficial effects

[0104] By dynamically adjusting the width and side pressure of each pass in large-reduction strip steel rolling, width control is dynamically adjusted according to on-site production conditions. The width coefficient is also dynamically adjusted, promptly correcting width variations in each pass to the roll gap settings. This effectively avoids inaccurate width issues in subsequent passes, eliminates fundamental deviations, and improves the accuracy of model settings. The dynamic adjustment of side pressure involves calculating the distribution coefficient of side pressure for each pass using a differential method, and utilizing previously calculated initial values ​​of side pressure to ensure a more reasonable distribution and a smoother transition to production. Adjusting the side pressure coefficient of the preceding passes in large-reduction strip steel rolling effectively prevents excessive width exceeding limits caused by excessive strip reduction in subsequent passes.

[0105] Technological Innovation Points

[0106] (1) Width correction module calculation algorithm and coefficient dynamic adjustment method.

[0107] (2) Dynamic adjustment method of lateral pressure and dynamic adjustment method of coefficient.

[0108] Implementation Case:

[0109] Specifications of strip steel rolled by 1780 hot rolling line:

[0110]

[0111] The control process is as follows:

[0112] Dynamic compensation table for width and lateral pressure of each pass

[0113]

[0114] Pressure reduction and confidence level for each pass

[0115]

[0116]

[0117] Comparison table of roll gap and side pressure before and after calculation correction for each pass

[0118]

[0119] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for improving the width accuracy of hot-rolled large-width strip steel, characterized in that, The method includes the following steps: S1. Configure the width and side pressure correction table for each pass of roughing rolling; S2, Dynamic adjustment module for the roll gap of vertical rolls in each pass of roughing mill; S3, Dynamic correction module for side pressure of roughing mill vertical rolls; In step S1, based on strip type, width classification, and width reduction classification, a roughing width and side pressure correction table is configured. Because the strip width changes, uneven stress occurs when the strip is subjected to force in the cross-section along the width direction. The dog-bone width calculated by the model deviates significantly from the natural width, affecting the final width control accuracy. Therefore, dynamic compensation for the strip's feel is required for different widths and reduction amounts. The structure of the dynamic compensation table is as follows: Table 1: Dynamic Compensation Table for Width and Side Pressure of Each Pass in Rough Rolling The initial value of the dynamic compensation value in this table is set to 0.

1. The initial value is used for the first calculation of the model. As the strip steel is continuously produced, the learning amount will be gradually corrected and eventually stabilized within a small range to meet the requirements of width control. S2, Dynamic adjustment module for the roll gap of vertical rolls in each pass of the roughing mill, as detailed below: During each strip rolling pass, there is a deviation between the model's set width and the actual rolled width. To prevent the width deviation from each pass from affecting the final rolling accuracy, it needs to be eliminated in each subsequent pass. Considering the measurement error of the width on site and the recovery amount of different width reductions, a confidence coefficient is added for different width reductions. When setting the width for the next pass, if the width deviation is less than 2mm, no correction is made; if the width deviation exceeds 2mm, the confidence coefficient is selected based on the width reduction amount of that pass. The final width setting method is as follows: Next pass roll gap deviation G ij+1 =Model calculation width w ij+1 +dw ij *a; The principle for configuring the confidence level of the deviation between the measured width and the calculated width of the strip for each pass is based on the strip width reduction. According to the production characteristics of Meigang hot rolling, the width reduction is categorized and associated with the confidence level. For strips with larger width reductions, the confidence level is calculated and configured as shown in Table 2 below. Table 2: Strip Steel Confidence Configuration Table The self-learning module in the model modifies the w in Table 1 according to the type, width, and reduction amount of the rolled strip. ij The data is used in the next setting of the corresponding pass width for this type of strip steel to ensure the elimination of basic deviations in this type of steel, and the accuracy of the model setting is getting higher and higher.

2. The method for improving the width accuracy of hot-rolled large-width strip steel according to claim 1, characterized in that, S3, Dynamic Correction Module for Side Pressure of Roughing Mill Vertical Roll, as detailed below: The calculation method for the reduction of the vertical roll in hot rolling roughing mill is as follows: Formula 1 in: eDraft i : Amount of pressure applied in each pass; W0 and H0: These are the entry width and thickness of the strip in this pass, respectively; W 目 The final target width of the rough rolling process; TEMP: Inlet temperature of the strip in this pass; ED i RD i : The diameter of vertical and horizontal rollers; SPRD i DOG i Naturally broad and wide, with a broad, dog-like bone structure; During control, considering the problem of excessive subsequent reduction and width exceeding the allowable width of the wide strip steel, a dynamic optimization was performed on the algorithm, as follows: Formula 2 in: i, j: rack number, track number; eDraft ij The final reduction amount allocation for each rack pass; eDraft ij0 : Initial calculation of reduction amount allocation for each rack pass; drf ij : Dynamic reduction distribution coefficient corresponding to each rack pass; drf ij The initial value is defined as 0.1 in Table 1, and the initial value is the same for each pass. During subsequent production, it needs to be dynamically adjusted, and the adjustment principle is calculated using the following formula: Efficiency per pass = Model set compression / Actual compression; Formula 3 Drfij = Drfij * efficiency per pass; Formula 4.

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