A method for improving the width accuracy at the exit of a roughing R1 stand

Abstract

The application discloses a method for improving the width precision of the outlet of a rough rolling R1 rack, which is based on the actual roll gap value of the horizontal pinch roll at the position of the large side pressure device after each large side pressure reduction, and establishes the correction of the reduction of the counter roll, so as to improve the width precision of the outlet of the rough rolling R1 rack. The method for improving the width precision of the outlet of the rough rolling R1 rack utilizes the deviation between the actual roll gap and the set roll gap of the horizontal pinch roll at the outlet of the large side pressure device, reuses the once recalculation, corrects the large side pressure dog bone width expansion, and reuses the calculation of the E1 counter roll reduction according to the target width of the outlet of the R1 horizontal roll, so as to improve the hit rate of the outlet width of the R1.

Description

Technical Field

[0001] This invention belongs to the field of steel rolling control technology, specifically relating to a method for improving the exit width accuracy of the R1 stand in roughing mills. Background Technology

[0002] In the production process of hot rolling lines, thousands of steel grades are frequently rolled, with new grades constantly being added. Due to the wide variation in steel composition, the hardness of the strip varies considerably. Common roughing mill layouts in hot rolling lines include equipment such as large side-pressure (SP), vertical rolls E1 / horizontal rolls R1, and vertical rolls E2 / horizontal rolls E2. During large side-pressure rolling, the efficiency can vary due to factors such as steel composition and furnace heating regime. In conventional models, for previously rolled steel grades, the dogbone width of the large side-pressure can be calculated relatively accurately based on the steel grade. However, for newly rolled steel grades, the dogbone width of the large side-pressure is often difficult to predict accurately. Furthermore, for special steel grades whose hardness varies significantly due to temperature, even for strips of the same specification and grade, different furnace models, heating times, and heating regimes can result in substantial variations in the dogbone width of the large side-pressure. All of these factors can lead to inaccurate width of the dogbone pattern under high side pressure. For steel grades with very high side pressure, fluctuations in reduction efficiency can cause the R1 stand exit width to be excessively wide or too narrow. At this time, due to the limited width adjustment capability of the vertical rolls in subsequent stands, the roughing mill exit will be excessively wide when the vertical rolls in subsequent passes are fully pressed, and the roughing mill exit will be too narrow when the vertical rolls in subsequent passes are empty, resulting in the roughing mill exit width not hitting the target.

[0003] The invention application with application number CN 2008100408960 discloses "a method for controlling the large side pressure of a slab", which includes the following steps: 1) calculating the large side pressure reduction, the initial pressure position LH, and the number of times N is applied; 2) after the slab enters the large side pressure, its head is sent to the initial pressure position LH; 3) at the initial pressure position LH, the slab remains stationary, and the large side pressure is applied N times; 4) after the slab head is applied in multiple applications, the slab moves forward and is rolled in the normal manner.

[0004] The invention application with application number CN 2008100419541 discloses "a method for improving the accuracy of hot rolling width control". It introduces the surface roughness of the rolls into the roughing width control and establishes a control model relationship between the width control amount 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 of each pass of each roll stand is determined. Then, based on the control model to predict the width expansion of each pass and the width reduction distribution principle, the target exit width of each pass is determined. This determines the vertical roll gap of each pass. By controlling the vertical roll gap, the width control of the exit of each pass is achieved, and finally, the target width of the rolled piece in the roughing area of ​​the hot rolling unit is controlled.

[0005] Invention application CN 2020110440802 discloses "a method for setting the width of roughing mill using a width gauge between stands in a hot rolling mill." The method includes the following steps: S1, to ensure data accuracy, the installation position of the width gauge needs to be determined; S2, adding model setting calculations to adjust the width of the strip; S3, feedback learning of the width adjustment. By adding a width gauge between R1 and R2 and performing setting and feedback learning, the width of intermediate passes can be effectively adjusted and corrected in real time, improving width accuracy. Summary of the Invention

[0006] To address the above problems, this invention provides a method for improving the exit width accuracy of the R1 stand in roughing mills, the specific technical solution of which is as follows:

[0007] A method for improving the exit width accuracy of a roughing mill R1 stand, characterized in that:

[0008] Based on the actual roll gap value of the horizontal pinch roll at the continuous station of the large side pressure equipment after each large side pressure reduction, a correction for the reduction of the vertical roll is established, and the accuracy of the exit width of the roughing mill R1 stand is improved accordingly.

[0009] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0010] The correction of the vertical roll reduction is established based on the actual roll gap value of the horizontal pinch roll. This is achieved by first calculating the corresponding large side pressure dog bone width based on the actual roll gap value of the horizontal pinch roll, and then determining the vertical roll reduction based on the target exit width of the R1 frame.

[0011] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0012] The vertical roll reduction is determined based on the width of the dog bone under large side pressure and the target exit width of the R1 frame. By combining the expressions for the target exit width of the R1 frame and the width of the dog bone of the vertical roll, a nonlinear function expression for the vertical roll reduction is formed, and then this function is solved to complete the calculation.

[0013] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0014] The solution for nonlinear functions is based on the secant method.

[0015] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0016] The maximum reduction of the vertical roll, determined by the vertical roll inlet width, vertical roll inlet thickness, and horizontal reduction of the R1 frame, is used as one of the initial values ​​for the truncated method iterative calculation.

[0017] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0018] The corresponding width of the large side pressure dog bone is calculated based on the actual roll gap value of the horizontal pinch roll, specifically:

[0019] First, based on the actual roll gap value of the horizontal pinch roll obtained from the sensor, the actual height of the dog bone on one side is calculated.

[0020] Secondly, based on the deviation between the actual dog bone height and the set dog bone height, the parameter adjustment coefficient is determined; and based on the determined parameter adjustment coefficient, the corresponding large side pressure dog bone width based on the actual roll gap value of the horizontal pinch roll is calculated.

[0021] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0022] The relationship between the height of the dog bone on one side and the gap between the horizontal pinch rolls is determined by the following formula:

[0023] H Dog =(H SP&Dog -H SP ) / 2,

[0024] In the above formula,

[0025] H Dog Dog bone height, unit: mm;

[0026] H SP&Dog : Horizontal pinch roll gap value, unit: mm;

[0027] H SP Thickness of slab after SP testing, unit: mm.

[0028] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0029] The process of determining the parameter adjustment coefficient based on the deviation between the actual dog bone height and the set dog bone height is as follows:

[0030] First, based on historical data on the height difference and width of the dog bone under large lateral pressure, the corresponding relationship between the height difference and the dog bone width adjustment coefficient is regressed.

[0031] Secondly, based on the correspondence between the slab exit width difference and the corresponding large side pressure dog bone height difference in historical data, the grade interval of the large side pressure dog bone height difference based on the slab exit width difference is completed, and the parameter adjustment coefficient under each grade interval is determined according to the correspondence between the height difference and the dog bone width, forming a correspondence table between the large side pressure dog bone height difference and the parameter adjustment coefficient.

[0032] Then, after each large lateral pressure action, the corresponding parameter adjustment coefficient is determined by looking up a table based on the height difference between the actual dog bone height and the set dog bone height.

[0033] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0034] The aforementioned "calculation of the corresponding large side pressure dogbone width based on the actual roll gap value of the horizontal pinch roll according to the determined parameter adjustment coefficient" is determined by the following formula:

[0035] dW SPDogRe =dW SPDog ×μ,

[0036] In the above formula,

[0037] dW SPDogRe : The width of the large side pressure dog bone after correction based on the actual roll gap value of the horizontal pinch roll, unit: mm;

[0038] dW SPDog Calculation of dog bone width under high lateral pressure, unit: mm;

[0039] μ: Parameter tuning coefficient, which is related to the actual height difference of the dog's bones.

[0040] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0041] The thickness increase H of the slab after SP stamping in the formula SP Determined according to the following formula:

[0042] H SP =(1 / ((1-dW) SP / W0)*(1+0.7*dW SP / W0))-1)*H0,

[0043] In the above formula,

[0044] H SP The thickness of the slab after SP testing is measured in mm.

[0045] dW SP : The amount of reduction under large lateral pressure, in mm;

[0046] W0: Heat value of hot-rolled incoming material width, unit: mm;

[0047] H0: Thickness of incoming slab, unit: mm.

[0048] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0049] The calculation of dog bone width dW under large lateral pressure. SPDog Determined according to the following formula:

[0050] dW SPDog =(1-SP) effic )*dW SP ,

[0051] SP effic Determined according to the following formula,

[0052]

[0053] In the above formula,

[0054] SP effic High side pressure reduction efficiency;

[0055] alfa, pa1, pa2, pa3, pa4, pa5, pa6: Calculation parameters for SP efficiency under large lateral pressure and dog bone width;

[0056] dW SPDog : Width of dog bone under high lateral pressure, unit: mm;

[0057] dW SP : The amount of reduction under large lateral pressure, in mm;

[0058] W0: Heat value of the width of the hot-rolled material, unit: mm.

[0059] A method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention is characterized in that:

[0060] Based on historical data on the height difference and width of the dog bone under large lateral pressure, the correspondence between the height difference and the width of the dog bone was regressed, based on the approximate equivalent processing of the dog bone shape as a triangle.

[0061] The present invention provides a method for improving the accuracy of the exit width of the R1 stand in roughing mills. By utilizing the deviation between the measured roll gap and the set roll gap of the horizontal pinch roll at the large side pressure exit, the calculation is restarted once to correct the width expansion of the large side pressure dog bone. Based on the target width of the R1 horizontal roll exit, the calculation of the E1 vertical roll reduction is restarted, thereby improving the hit rate of the R1 exit width. Attached Figure Description

[0062] Figure 1 This is a schematic diagram illustrating the control and adjustment process after incorporating the technical solution of the present invention;

[0063] Figure 2 This is a schematic diagram of the process for improving the R1 outlet width accuracy according to the present invention;

[0064] Figure 3 This is a schematic diagram showing the calculated dog bone shape (dashed line) and the actual dog bone shape (solid line) of the strip after it has undergone large lateral pressure SP in this invention.

[0065] Figure 4 This is a graph showing the relationship between the total width of the R1 outlet and the deviation between the actual roll gap value and the set roll gap value of the horizontal pinch roll after large side pressure.

[0066] Figure 5 This is a schematic diagram of the measured width of the R1 rack outlet in an embodiment of the present invention;

[0067] Figure 6 This is a schematic diagram comparing the set roll gap and the actual roll gap of the horizontal pinch roll after large side pressure in an embodiment of the present invention. Detailed Implementation

[0068] The following is a detailed description of a method for improving the exit width accuracy of a roughing mill R1 stand according to the present invention, based on the accompanying drawings and specific embodiments.

[0069] A method for improving the exit width accuracy of the R1 stand in roughing mills involves establishing a correction for the amount of vertical roll reduction based on the actual roll gap value of the horizontal pinch roll at the continuous station of the large side pressure equipment after each large side pressure reduction, thereby improving the exit width accuracy of the R1 stand in roughing mills.

[0070] in,

[0071] The correction of the vertical roll reduction is established based on the actual roll gap value of the horizontal pinch roll. This is achieved by first calculating the corresponding large side pressure dog bone width based on the actual roll gap value of the horizontal pinch roll, and then determining the vertical roll reduction based on the target exit width of the R1 frame.

[0072] in,

[0073] The vertical roll reduction is determined based on the width of the dog bone under large side pressure and the target exit width of the R1 frame. By combining the expressions for the target exit width of the R1 frame and the width of the dog bone of the vertical roll, a nonlinear function expression for the vertical roll reduction is formed, and then this function is solved to complete the calculation.

[0074] in,

[0075] The solution for nonlinear functions is based on the secant method.

[0076] in,

[0077] The maximum reduction of the vertical roll, determined by the vertical roll inlet width, vertical roll inlet thickness, and horizontal reduction of the R1 frame, is used as one of the initial values ​​for the truncated method iterative calculation.

[0078] in,

[0079] The corresponding width of the large side pressure dog bone is calculated based on the actual roll gap value of the horizontal pinch roll, specifically:

[0080] First, based on the actual roll gap value of the horizontal pinch roll obtained from the sensor, the actual height of the dog bone on one side is calculated.

[0081] Secondly, based on the deviation between the actual dog bone height and the set dog bone height, the parameter adjustment coefficient is determined; and based on the determined parameter adjustment coefficient, the corresponding large side pressure dog bone width based on the actual roll gap value of the horizontal pinch roll is calculated.

[0082] in,

[0083] The relationship between the height of the dog bone on one side and the gap between the horizontal pinch rolls is determined by the following formula:

[0084] H Dog =(H SP&Dog -H SP ) / 2,

[0085] In the above formula,

[0086] H Dog Dog bone height, unit: mm;

[0087] H SP&Dog : Horizontal pinch roll gap value, unit: mm;

[0088] H SP Thickness of slab after SP testing, unit: mm.

[0089] in,

[0090] The process of determining the parameter adjustment coefficient based on the deviation between the actual dog bone height and the set dog bone height is as follows:

[0091] First, based on historical data on the height difference and width of the dog bone under large lateral pressure, the corresponding relationship between the height difference and the width of the dog bone was regressed.

[0092] Secondly, based on the correspondence between the slab exit width difference and the corresponding large side pressure dog bone height difference in historical data, the grade interval of the large side pressure dog bone height difference based on the slab exit width difference is completed, and the parameter adjustment coefficient under each grade interval is determined according to the correspondence between the height difference and the dog bone width, forming a correspondence table between the large side pressure dog bone height difference and the parameter adjustment coefficient.

[0093] Then, after each large lateral pressure action, the corresponding parameter adjustment coefficient is determined by looking up a table based on the height difference between the actual dog bone height and the set dog bone height.

[0094] in,

[0095] Based on historical data on the height difference and width of the dog bone under large lateral pressure, the corresponding relationship between the height difference and the dog bone width adjustment coefficient was regressed, based on the approximate equivalent processing of the dog bone shape as a triangle.

[0096] in,

[0097] The aforementioned "calculation of the corresponding large side pressure dogbone width based on the actual roll gap value of the horizontal pinch roll according to the determined parameter adjustment coefficient" is determined by the following formula:

[0098] dW SPDogRe =dW SPDog ×μ,

[0099] In the above formula,

[0100] dW SPDogRe : The width of the large side pressure dog bone after correction based on the actual roll gap value of the horizontal pinch roll, unit: mm;

[0101] dW SPDog Calculation of dog bone width under high lateral pressure, unit: mm;

[0102] μ: Parameter tuning coefficient, which is related to the actual height difference of the dog's bones.

[0103] in,

[0104] The thickness increase H of the slab after SP stamping in the formula SP Determined according to the following formula:

[0105] H SP =(1 / ((1-dW) SP / W0)*(1+0.7*dW SP / W0))-1)*H0,

[0106] In the above formula,

[0107] H SP The thickness of the slab after SP testing is measured in mm.

[0108] dW SP : The amount of reduction under large lateral pressure, in mm;

[0109] W0: Heat value of hot-rolled incoming material width, unit: **;

[0110] H0: Thickness of the incoming slab, unit: mm.

[0111] in,

[0112] The calculation of dog bone width dW under large lateral pressure. SPDog Determined according to the following formula:

[0113] dW SPDog =(1-SP) effic )*dW SP ,

[0114] SP effic Determined according to the following formula,

[0115]

[0116] In the above formula,

[0117] SP effic High side pressure reduction efficiency;

[0118] alfa, pa1, pa2, pa3, pa4, pa5, pa6: Calculation parameters for SP efficiency under large lateral pressure and dog bone width;

[0119] dW SPDog : Width of dog bone under high lateral pressure, unit: mm;

[0120] dW SP : The amount of reduction under large lateral pressure, in mm;

[0121] W0: Heat value of the width of the hot-rolled material, unit: mm.

[0122] Working principle and process

[0123] The overall control diagram after incorporating the technical solution of this invention into the existing technology is shown below. Figure 1 As shown, this invention utilizes the deviation between the set value and the actual value of the horizontal roll at the exit of the large side-pressure equipment to correct the width expansion of the large side-pressure dog bone, recalculates the E1 large vertical roll reduction, improves the control accuracy of the R1 stand exit width, and ensures the roughing mill exit width; according to Figure 1The overall control process is as follows: After the hot-rolled strip is drawn, a pre-calculation is initiated to determine the target width of the horizontal roll exit for each forward pass based on the roughing target width. When the strip passes the horizontal pinch roll at 1 / 3 of its length at the exit of the large side-pressure SP equipment, the actual roll gap of the horizontal pinch roll is set and sent to the roughing width control model. The width control model corrects the dog-bone width expansion of the large side-pressure based on the deviation between the actual width after large side-pressure and the set roll gap. Then, based on the R1 horizontal roll reduction and the target width at the R1 horizontal roll exit, the reduction amount of the E1 vertical roll is iteratively calculated to ensure that the deviation between the actual width at the R1 horizontal roll exit and the target width remains within a reasonable range. Width measuring instruments are arranged after the R1 and R2 equipment. During each forward pass of the roughing mill, the reduction amount of the vertical rolls in subsequent passes is readjusted based on the measured width value to ensure that the deviation between the actual width at the roughing mill exit and the calculated width remains within a reasonable range.

[0124] and Figure 1 The specific process and setting principle of the technical solution in this case are as follows:

[0125] 1. Related Broadened Computational Model

[0126] After hot-rolled strip steel is rolled sequentially by large side pressure SP, vertical roll E1, and horizontal roll R1, the exit width W R1 It consists of the following parts:

[0127] W R1 =W E1 +dW Spread +dW Dog (1)

[0128] W E1 =W0-dW SP -dW E1 (2)

[0129] dW Dog =dW SPDog +dW E1Dog (3)

[0130] in:

[0131] W E1 : is the exit width of vertical roller E1;

[0132] dW Spread : refers to the horizontal width of the horizontal roller R1;

[0133] dW Dog The dogbread width of the large side pressure SP and vertical roll E1 is produced by the thickening and edge dogbread of the hot-rolled strip after passing through the large side pressure SP; the edge dogbread is produced after passing through the vertical roll E1; the dogbread of the large side pressure SP and vertical roll E1 will produce their own dogbread width after being rolled by the R1 horizontal roll.

[0134] W0: Heat value of the width of the hot-rolled material;

[0135] dW SP : This refers to the reduction amount under large lateral pressure;

[0136] dW E1 : This refers to the amount of pressure applied to the vertical roller E1;

[0137] dW SPDog : The dog's bones are broadened due to high lateral pressure;

[0138] dW E1Dog : For the E1 dog bone width;

[0139] The dog bone expansion and thickening model of the SP under high lateral pressure is as follows:

[0140]

[0141] dW SPDog =(1-SP) effic )*dW SP (5)

[0142] H SP =(1 / ((1-dW) SP / W0)*(1+0.7*dW SP / W0))-1)*H0 (6)

[0143] in:

[0144] SP effic : This refers to the efficiency of reducing pressure under high lateral pressure;

[0145] alfa, pa1, pa2, pa3, pa4, pa5, pa6: These are the calculation parameters for SP efficiency under large lateral pressure and dog bone width.

[0146] H0: Thickness of the incoming slab.

[0147] H SP The slab will thicken after SP pressing, and dog bones will form at the edges.

[0148] Note: SP is a technical term. SP equipment presses down the slab by stepping on it, with each step being about 0.4m. In contrast, the pressing down of the vertical roller is a continuous process. SP adjusts the width by judging the width through continuous tapping. SP has a strong width adjustment capability. When tapping the slab, it will form dog bones on both sides and increase the thickness of the strip to a certain extent.

[0149] The vertical roller dog bone width expansion model is as follows:

[0150] dW E1Dog =(W entry -Wexit )×e α (7)

[0151]

[0152] Among them: W entry : Width of vertical roller inlet side; W exit : Width of the vertical roller exit side; H entry : Vertical roll entry side thickness; R: Vertical roll radius; A1, A2, A3, A4 are dog bone width parameters.

[0153] The horizontal expansion model is as follows:

[0154]

[0155] Wherein: Temperature influence coefficient: T α = -0.0004*T + 1.5;

[0156] Size influence factor:

[0157] T: Temperature;

[0158] H entry : Inlet thickness (rack entrance);

[0159] H exit : Outlet thickness (rack inlet);

[0160] W entry : Inlet width (rack entrance);

[0161] R: Horizontal roller radius.

[0162] Method for correcting the gap between two horizontal rollers at the outlet under large side pressure and widening the dog bone width under large side pressure.

[0163] Large side-pressure SP (Special Pressure Roller) is an important width control device in the roughing rolling zone. Taking the common SMS large side-pressure mill as an example, its equipment has a maximum side-pressure capacity of 350mm, which can reduce the width of various incoming slabs to the width required for roughing rolling, effectively improving the slab utilization rate and greatly benefiting the scheduling and width control. Due to the large reduction capacity of the large side-pressure mill, the slab in the widened section is more likely to penetrate towards the center, thus the reduction efficiency is better than that of the vertical roll mill. After the slab passes through the large side-pressure mill, in terms of thickness, it will increase in thickness on one hand, and dog bones will form on both sides in the width direction, such as... Figure 3 As shown. The large lateral pressure model takes into account the thickening and dog-bone effect of the slab under large lateral pressure, and calculates the set value of the horizontal pinch roll gap after large lateral pressure. Figure 3The height of the dashed line represents the set value of the horizontal pinch roll gap calculated by the large lateral pressure model. In this invention, when the actual slab passes through the horizontal pinch roll after large lateral pressure, the actual roll gap value is fed into the roughing width model. Figure 3 The height of the solid line section; the model can recalculate the dog bone formed by the slab after the large side pressure equipment based on the actual roll gap of the horizontal pinch roll after the large side pressure, and the width of the dog bone formed after the dog bone is rolled by the horizontal roll R1; finally, the model readjusts the reduction amount of the large vertical roll E1 based on the target width of the horizontal roll R1 exit.

[0164] Assuming the strip thickness is H0, according to Formula 6, the thickness increase of the slab after passing through the large side-pressing equipment is H. SP The large side pressure model considers the dog bones formed on both sides of the slab in the width direction, and the calculated gap of the horizontal pinch rolls at the large side pressure outlet is set to H. SP&DogCalc The actual roll gap value of the horizontal exit pinch roll is H. SP&DogAct After the slab undergoes large lateral pressure, the model calculates the height H of the dog bone formed on one side. DogCalc Actual unilateral dog bone height H DogAct As shown in the following formula.

[0165] H DogCalc =(H SP&DogCalc -H SP ) / 2 (10)

[0166] H DogAct =(H SP&DogAct -H SP ) / 2 (11)

[0167] Model pre-calculation of dogbone width dW under large lateral pressure SP SPDog It can be calculated using formulas 4 and 5. After the slab passes through the horizontal pinch rolls under large lateral pressure, the calculation is restarted to calculate the dogbone width dW of the large lateral pressure SP. SPDogRe .

[0168] dW SPDogRe =dW SPDog ×μ (12)

[0169] μ: Parameter tuning coefficient, related to the actual height difference of the dog's bones. The specific confirmation process is as follows:

[0170] First, based on historical data of the height difference and width of the large side-pressure dog bone, the correspondence between the height difference and the dog bone width is regressed. Second, based on the correspondence between the slab exit width difference and the corresponding large side-pressure dog bone height difference in historical data, the grade intervals of the large side-pressure dog bone height difference based on the slab exit width difference are completed. Then, based on the correspondence between the height difference and the dog bone width, the adjustment coefficients for each grade interval are determined, forming a table of the correspondence between the large side-pressure dog bone height difference and the adjustment coefficients. Finally, after each large side-pressure action, based on the height difference between the actual dog bone height and the set dog bone height, the corresponding adjustment coefficients are determined by looking up the table. The theoretical basis for this is that the actual difference in exit width is considered to be mainly caused by the change in the width of the large side-pressure dog bone, and the width of the large side-pressure dog bone corresponds to the height difference of the large side-pressure dog bone. Furthermore, the height of the dog bone on one side (whether calculated or actual) can be obtained from the corresponding horizontal pinch roll gap.

[0171] 3. After the slab undergoes large side pressure SP, the reduction amount of the large vertical roller E1 is recalculated.

[0172] In the roughing mill pre-calculation process, the width load distribution model determines the target width of the horizontal roll exit, the maximum side pressure, and the vertical roll reduction for each forward pass based on the target width of the roughing mill. Model details are omitted. During the pre-calculation, the following formula holds true.

[0173] W R1 =W0-dW SP +dW SPDog -dW E1 +dW E1Dog +dW Spread (13)

[0174] After the slab undergoes large side-pressure rolling, a recalculation is performed. At this point, the thickness reduction does not change significantly, so the horizontal width of R1 can be assumed to remain unchanged. However, due to the change in the dog-bone width caused by the large side-pressure rolling, the reduction amount of E1 needs to be adjusted to ensure that the target width of R1 at the exit remains unchanged. Consequently, both the reduction amount of E1 and the dog-bone width will change.

[0175] W R1 =W0-dW SP +dW SPDogRe -dW E1Re +dW E1DogRe +dW Spread (14)

[0176] Wherein: dW E1Re For the new vertical roll reduction;

[0177] dW E1DogRe The dog bone width calculated according to formulas 7-8 can be transformed into dW. E1DogRe =f DogCalc (dWE1Re ).

[0178] Therefore, Formula 14 can be converted to:

[0179] W R1 =W0-dW SP +dW SPDogRe -dW E1Re +f DogCalc (dW E1Re )+dW Spread (15)

[0180] Let x = dW E1Re Nonlinear equations:

[0181] F(x) = W0 - dW SP +dW SPDogRe -x+f DogCalc (x)+dW Spread -W R1 (16)

[0182] The reduction of the large vertical roller E1 was calculated through iterative methods using Newton's secant method. (See also...) Figure 2 In the calculation, the maximum reduction of the vertical roll, determined by the vertical roll inlet width, vertical roll inlet thickness, and horizontal reduction of the R1 frame, is used as one of the initial values ​​for the truncated method iterative calculation, to ensure that the calculated results are within the process constraints.

[0183] Example

[0184] Taking a certain steel grade of the same specification and layer produced by a hot rolling production line of Baosteel as an example, its large side pressure SP reduction, vertical roll E1 reduction, and horizontal roll R1 reduction are roughly the same. Due to the influence of the heating regime and temperature sensitivity of the steel grade, the sum of its large side pressure dog bone width, vertical roll dog bone width, and horizontal width has the following relationship with the deviation between the actual value and the set value of the horizontal pinch roll after large side pressure.

[0185] Figure 4 In the graph, the horizontal axis represents the deviation between the actual roll gap and the set roll gap of the horizontal pinch roll after large side pressure, and the vertical axis represents the R1 exit width minus the E1 vertical roll gap value, i.e., the sum of the large side pressure dog bone width, the E1 vertical roll dog bone width expansion, and the R1 horizontal width expansion. It can be seen from the graph that the greater the deviation between the actual roll gap and the set roll gap of the horizontal pinch roll after large side pressure, the greater the sum of the large side pressure dog bone width, the E1 vertical roll dog bone width expansion, and the R1 horizontal width expansion. Because the vertical and horizontal rolls have limited compression, their width expansion is less affected by temperature; however, the large side pressure equipment has a strong width adjustment capability, and the resulting dog bone width expansion is more significantly affected by temperature.

[0186] Taking a strip of steel actually rolled on-site as an example:

[0187] The entrance width W0 = 1774.2107 mm;

[0188] The inlet thickness H0 = 243.41927 mm;

[0189] The thickness reduction of the R1 horizontal roller is 15.451797 mm;

[0190] Pre-calculated width load distribution results:

[0191] SP reduction amount dW SP It is 246.02602 mm;

[0192] After SP is pressed down, considering the increase in thickness, the slab thickness H SP It is 257.60303 mm;

[0193] SP's dog bone width dW SPDog It is 24.825790mm;

[0194] The amount of reduction dW of vertical roller E1 E1 It is 30mm;

[0195] dogbone width dW of vertical roller E1 E1Dog It is 12.635434 mm;

[0196] The horizontal width of the horizontal roller R1 is 10.077736 mm.

[0197] The target exit width of the horizontal roller R1 is 1545.72 mm.

[0198] The actual R1 exit width after slab rolling is shown in Figure 5 below.

[0199] Figure 5 The horizontal axis represents the location point, and the vertical axis represents the measured width. Figure 5 It can be seen that the actual width of the strip at the R11 exit is 1575mm, while the target width at the R1 exit is 1545.72mm. The R1 exit is seriously over-width. Since the deviation of the dog bone width of the horizontal and vertical rolls is limited, while the amount of pressure reduction of the large side pressure SP is large, it can be considered that most of the deviation is caused by the large deviation between the calculated and actual dog bone width formed by the large side pressure.

[0200] Figure 6 In the series, Series 1 represents the actual roll gap after large side pressure, and Series 2 represents the set roll gap after large side pressure; the unit is meters (m). Figure 6 It can be seen that the actual value of the horizontal pinch roll gap after large side pressure deviates significantly from the set value. The strip may be affected by factors such as temperature, resulting in different dog bone heights. The dog bone width of the strip under large side pressure SP is recalculated according to Formula 12 as: dW SPDogRe = 36.8658mm.

[0201] While maintaining the target width of R1 outlet, the reduction of E1 is calculated to be 51.6555 using Newton's truncated chord method: the dogbone width of E1 is 22.2473 mm.

[0202] For existing hot rolling production lines, the heating furnaces vary in model and heating capacity. When the width reduction is large and the SP side pressure is high, the dog-bone width fluctuates greatly. This invention provides a method to improve the accuracy of the R1 stand exit width in roughing mills. For severely oversized or overly narrow strips, it can effectively control the deviation between the actual R1 exit width and the target width, keeping the error within 8mm.

Claims

1. A method for improving the exit width accuracy of a roughing mill R1 stand, characterized in that: Based on the actual roll gap value of the horizontal pinch roll at the successive station of the large side pressure equipment after each large side pressure reduction, a correction for the vertical roll reduction is established. Based on this correction, the accuracy of the exit width of the roughing mill R1 stand is improved. The correction for the vertical roll reduction is established based on the actual roll gap value of the horizontal pinch roll. This is done by first calculating the corresponding large side pressure dogbone width based on the actual roll gap value of the horizontal pinch roll, and then determining the vertical roll reduction based on the target exit width of the R1 frame. The corresponding width of the large side pressure dog bone is calculated based on the actual roll gap value of the horizontal pinch roll, specifically: First, based on the actual roll gap value of the horizontal pinch roll obtained from the sensor, the actual height of the dog bone on one side is calculated. Secondly, based on the deviation between the actual dog bone height and the set dog bone height, the parameter adjustment coefficient is determined; and based on the determined parameter adjustment coefficient, the corresponding large side pressure dog bone width is calculated based on the actual roll gap value of the horizontal pinch roll. The relationship between the height of the dog bone on one side and the gap between the horizontal pinch rolls is determined by the following formula: ， In the above formula, Dog bone height, unit: mm; : Horizontal pinch roll gap value, unit: mm; Thickness of slab after SP testing, unit: mm.

2. The method for improving the exit width accuracy of a roughing mill R1 stand according to claim 1, characterized in that: The vertical roll reduction is determined based on the width of the dog bone under large side pressure and the target exit width of the R1 frame. By combining the expressions for the target exit width of the R1 frame and the width of the dog bone of the vertical roll, a nonlinear function expression for the vertical roll reduction is formed, and then this function is solved to complete the calculation.

3. The method for improving the exit width accuracy of a roughing mill R1 stand according to claim 2, characterized in that: ， The solution of nonlinear functions is based on the secant method.

4. The method for improving the exit width accuracy of the R1 stand in roughing mills according to claim 3, characterized in that: The maximum reduction of the vertical roll, determined by the vertical roll inlet width, vertical roll inlet thickness, and horizontal reduction of the R1 frame, is used as one of the initial values ​​for the truncated method iterative calculation.

5. A method for improving the exit width accuracy of a roughing mill R1 stand according to claim 1, characterized in that: , The process of determining the parameter adjustment coefficient based on the deviation between the actual dog bone height and the set dog bone height is as follows: First, based on historical data on the height difference and width of the dog bone under large lateral pressure, the corresponding relationship between the height difference and the dog bone width adjustment coefficient is regressed. Secondly, based on the correspondence between the slab exit width difference and the corresponding large side pressure dog bone height difference in historical data, the grade interval of the large side pressure dog bone height difference based on the slab exit width difference is completed, and the parameter adjustment coefficient under each grade interval is determined according to the correspondence between the height difference and the dog bone width, forming a correspondence table between the large side pressure dog bone height difference and the parameter adjustment coefficient. Then, after each large lateral pressure action, the corresponding parameter adjustment coefficient is determined by looking up a table based on the height difference between the actual dog bone height and the set dog bone height.

6. The method for improving the exit width accuracy of a roughing mill R1 stand according to claim 1, characterized in that: The aforementioned "calculation of the corresponding large side pressure dogbone width based on the actual roll gap value of the horizontal pinch roll according to the determined parameter adjustment coefficient" is determined by the following formula: ， In the above formula, : The width of the large side pressure dog bone after correction based on the actual roll gap value of the horizontal pinch roll, unit: mm; Calculation of dog bone width under high lateral pressure, unit: mm; : The parameter adjustment coefficient is related to the actual height difference of the dog's bones.

7. The method for improving the exit width accuracy of a roughing mill R1 stand according to claim 1, characterized in that: The formula for slab thickness increase after SP testing Determined according to the following formula: ， In the above formula, The thickness of the slab after SP testing is measured in mm. : The amount of reduction under large lateral pressure, in mm; : Inlet width of the vertical roll of strip steel, unit: mm; : Thickness of incoming slab, unit: mm.

8. A method for improving the exit width accuracy of a roughing mill R1 stand according to claim 6, characterized in that: The calculation of dog bone width under large lateral pressure. Determined according to the following formula: ， Among them Determined according to the following formula, In the above formula, High side pressure reduction efficiency; , , , , , , Calculation parameters for SP efficiency under high lateral pressure and dog bone width; : Width of dog bone under high lateral pressure, unit: mm; : The amount of reduction under large lateral pressure, in mm; : Inlet width of the vertical roll of strip steel, unit: mm.

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