A method for width control in a hot continuous roughing cross rolling process

Abstract

The application relates to a width control method for a hot continuous rough rolling cross-rolling process, which comprises the following steps: determining slab parameters, product parameters, roll parameters and process parameters; calculating the reduction of each pass of the double-stand rough rolling mill and the rolling temperature of each pass; calculating the width free spread of each pass, the total free spread and the width value after the spread; calculating the total width reduction of the rough rolling mill, the width reduction of each pass and the width of the steel plate after the reduction; determining the free spread coefficient and the dog bone recovery spread coefficient of the current steel plate during the cross-rolling according to the dog bone recovery spread coefficient and the free spread coefficient of the last rolled steel plate; calculating the free spread after the reduction and the dog bone recovery after the reduction; calculating the new width reduction of each pass and the set value of the width of the steel plate after the reduction; and calculating the stand opening control value of the rolling width control process of each pass according to the set value of the width of the steel plate of each pass.

Description

Technical Field

[0001] This invention relates to the field of hot continuous rolling technology, and in particular to a method for width control in the cross-rolling process of hot continuous roughing. Background Technology

[0002] Hot-rolled strip products are fundamental raw materials for high-end products in defense, transportation, and energy sectors. Despite a high level of automation in their processing, common problems such as poor three-dimensional dimensional control accuracy and poor strip shape persist. Width control accuracy during hot-rolling is a crucial indicator of strip quality. However, in actual hot-rolling production, during cross-rolling processes involving steel grade, thickness, and width changes, the long-term learning coefficients used in the control model are based on the parameters from the previous production of the same product. In the calculation of the rolling specifications for this change, changes in equipment conditions, operating conditions, and rolling states occur, and the model fails to adjust to these changes, leading to width control deviations. Therefore, a method for width control during cross-rolling processes in hot-rolling is urgently needed to ensure the stability and width control accuracy of the hot-rolled strip steel rolling process. Summary of the Invention

[0003] To address the problem of large width control deviations during cross-rolling processes such as steel grade switching, thickness switching, and width switching in hot continuous rolling, this invention provides a width control method for the cross-rolling process of hot continuous roughing.

[0004] The present invention provides a method for width control in a hot continuous rolling roughing cross-rolling process, comprising:

[0005] Step 1: Determine the billet parameters, product parameters, roll parameters, and process parameters;

[0006] Step 2: Heat the continuous casting billet to 1180-1220℃, and the average temperature difference of the continuous casting billet during the cross rolling process is <20℃;

[0007] Step 3: Calculate the reduction of the flat rolls in each pass of the roughing mill double stand, and calculate the rolling temperature of each pass based on the reduction.

[0008] Step 4: Calculate the free width expansion for each pass based on the reduction amount and rolling temperature, and obtain the total free width expansion and the width value after expansion.

[0009] Step 5: Based on the width value after widening, the target width of the product, and the free widening amount, calculate the total width reduction of the vertical rolls of the roughing mill, the width reduction of each pass, and the width of the steel plate after widening.

[0010] Step 6: Based on the steel grade, width, dogbone recovery width extension coefficient, and free width extension coefficient of the previous rolled steel plate, determine the free width extension coefficient and dogbone recovery width extension coefficient of the current steel plate during cross rolling;

[0011] Step 7: Calculate the free width expansion and dog bone recovery amount after flat roll rolling based on the width reduction amount of each pass;

[0012] Step 8: Based on the sum of the dog bone recovery amount and free width expansion amount after each pass of flat roll rolling, set the new width reduction amount for each pass and the set value of the width of the steel plate after width reduction for each pass.

[0013] Step 9: Calculate the vertical roll opening control value for each pass's rolling width control process based on the set value of the steel plate width for each pass.

[0014] This invention provides a width control method for the cross-rolling process of hot continuous rolling roughing, solving the problem of low width control accuracy when switching steel grades or specifications during the hot continuous rolling roughing process. Simultaneously, this invention provides width spread model adjustment factors for different temperature variations, quantifies the free width spread and dog-bone recovery correction factors when steel grade strength and specification changes, and rationally calculates the roughing roll opening setting value that meets production and quality requirements. Attached Figure Description

[0015] Figure 1 This is a flowchart of a width control method for a hot continuous rolling roughing cross rolling process according to the present invention; Detailed Implementation

[0016] like Figure 1 As shown, a width control method for a hot continuous rolling roughing cross-rolling process according to the present invention includes:

[0017] Step 1: Determine the billet parameters, product parameters, roll parameters, and process parameters.

[0018] The parameters of the billet include: billet steel grade, chemical composition, billet thickness, billet width, and billet length.

[0019] Product parameters include: target width for rough rolling, target thickness for rough rolling, and target temperature for rough rolling.

[0020] Roll parameters include: work roll diameter, vertical roll diameter, vertical roll wear, and vertical roll thermal expansion.

[0021] The process parameters include: the steel plate inlet speed, the steel plate outlet speed, and the initial rolling temperature of the steel plate entering the roughing mill.

[0022] In specific implementation, the billet steel grade is Q345B, and the chemical composition and mass percentage content are as follows: C: 0.014%, Mn: 1.43%, Si: 0.21%, Nb: 0.018%, Ti: 0.027%, P: 0.008%, S: 0.0018%, with the remainder being Fe and unavoidable impurities.

[0023] In practice, the billet thickness is 210mm, the billet width is 1250mm, and the billet length is 9000mm. The target thickness for rough rolling is 30mm, the target width for rough rolling is 1200mm, and the target temperature for rough rolling is 1050℃. The diameters of the R1 and R2 work rolls are 1200mm, the diameter of the vertical rolls is 1150mm, the wear of the vertical rolls is 0mm, and the thermal expansion of the vertical rolls is 0.1mm. The inlet and outlet speeds of the steel plate are both 2mm / s, and the initial rolling temperature of the steel plate entering the roughing mill is 1180℃.

[0024] Step 2: Heat the continuous casting billet to 1180-1220℃, and the average temperature difference of the continuous casting billet during the cross rolling process is <20℃.

[0025] In practice, the total heating time of the preheating section is 2.2h to 2.5h, the time of the soaking section is 1.4h to 1.7h, and the total time in the furnace is 3.6h to 4.2h.

[0026] Step 3: Calculate the reduction of the flat rolls for each pass of the roughing mill double stand, and calculate the rolling temperature for each pass based on the reduction. Specifically:

[0027] Step 3.1: The roughing rolling process adopts a two-stand 3+3 pass rolling model. Calculate the reduction of the flat rolls in each pass of the roughing rolling two-stand model. The calculation formula is as follows:

[0028] Δh i =h i-1 ×ε i

[0029] In the formula, Δh i h is the reduction in the i-th pass, in mm. i-1 ε is the thickness of the (i-1)th pass, in mm; i It is the reduction rate of the i-th pass.

[0030] Step 3.2: Calculate the exit thickness of each pass in the roughing mill. The calculation formula is as follows:

[0031] h i =h i-1 -Δh i

[0032] In the formula, h i It represents the thickness of the i-th pass, in mm.

[0033] Step 3.3: Calculate the rolling temperature for each pass. The calculation formula is as follows:

[0034]

[0035] In the formula, T i T is the rolling temperature of the i-th pass. i-1t is the rolling temperature of the (i-1)th pass, in °C. i It is the rolling time of the i-th steel plate, in seconds.

[0036] Inlet thickness (mm) 210 160 122.9 89.1 68 45 Export thickness (mm) 160 122.9 89.1 68 45 30 Indentation (mm) 50 37.1 33.8 21.1 23 15 Relative reduction rate (%) 23.8 23.2 27.5 23.7 33.8 33.3 Rolling temperature (°C) 1149.40 1146.86 1143.38 1136.49 1125.17 1104.73

[0037] Step 4: Calculate the free width expansion for each pass based on the reduction amount and rolling temperature, and obtain the total free width expansion and the width value after expansion, specifically as follows:

[0038] Step 4.1: Calculate the free width extension and width value for each track. The calculation formula is as follows:

[0039]

[0040] ψ i =1.0+(800.0-T) i )×0.00148

[0041] W i =W i-1 +ΔB i

[0042] In the formula, ΔB i W is the width free expansion amount of the i-th pass, in mm; i W is the width of the steel plate in the i-th pass, in mm. i-1 ψ is the width of the steel plate in the (i-1)th pass, in mm; i It is the broadening model adjustment factor for different temperature variations; Coff spread_0 The free spread coefficient of the previous steel plate ranges from 0.8 to 1.2; α is the width-to-thickness ratio sensitivity coefficient during the free spread process; β is the contact arc length sensitivity coefficient; γ is the roll diameter sensitivity coefficient; b0, b1, b2, and b3 are the first fitting coefficients, with b0 ranging from -1.8 to -1.5, b1 ranging from 0.3 to 0.4, b2 ranging from 0.01 to 0.02, and b3 ranging from 0.01 to 0.02; R is the radius of the working roll of the rolling mill, in mm.

[0043] Step 4.2: Calculate the total free width and the width after expansion. The calculation formula is as follows:

[0044]

[0045] W sprd =W slb +ΔB sprd

[0046] In the formula, ΔB sprd This is the total free stretch, in mm; W slbThis refers to the width of the billet, in mm; W sprd This is the width value after widening, in mm.

[0047] Step 5: Based on the expanded width value, the target width of the product, and the free expansion amount, calculate the total width reduction of the vertical rolls in the roughing mill, the width reduction for each pass, and the width of the steel plate after width reduction. Specifically:

[0048] Step 5.1: Calculate the total width reduction of the vertical rolls in the roughing mill. The calculation formula is as follows:

[0049] ΔB decre =W sprd -W prod

[0050] In the formula, ΔB decre This refers to the total width reduction of the vertical rolls in the roughing mill, in mm; W prod This is the target width of the product, in mm.

[0051] Step 5.2: Calculate the width reduction for each pass, using the following formula:

[0052] ΔB decre_i =ΔB decre ×Dist i

[0053] In the formula, ΔB decre_i Dist is the width reduction for the i-th pass, in mm; i It is the proportional coefficient for the width reduction of each vertical roll rolling pass, and its value ranges from 0.2 to 0.3.

[0054] Step 5.3: Calculate the width of the reduced steel plate. The calculation formula is as follows:

[0055] W i (1) =W i-1 +ΔB i -ΔB decre_i

[0056] Among them, W i (1) It is the width of the steel plate after the width reduction, in mm.

[0057] Step 6: Based on the steel grade, width, dogbone recovery width spread coefficient, and free width spread coefficient of the previous rolled steel plate, determine the free width spread coefficient and dogbone recovery width spread coefficient of the current steel plate during cross rolling, specifically as follows:

[0058] Step 6.1: Calculate the free width spread coefficient of the current steel plate during cross rolling according to the following formula:

[0059]

[0060] Where, σ last σ represents the deformation resistance of the previous steel plate, in MPa. cur W represents the deformation resistance of the steel plate during cross-rolling, in MPa. last W represents the target width of the previous steel plate, in mm. prod Coff represents the target product width of the steel plate during cross-rolling, in mm. spread_0 This is the free spread coefficient of the previous steel plate.

[0061] Step 6.2: Calculate the dogbone recovery coefficient of the current steel plate during cross-rolling according to the following formula:

[0062]

[0063] Among them, Coff recov_0 The dog bone recovery coefficient of the previous steel plate.

[0064] Step 7: Based on the width reduction amount in each pass, calculate the free width expansion and dog-bone recovery amount after flat roll rolling. Specifically:

[0065] Step 7.1: Calculate the free width extension after the width reduction and flat roll rolling;

[0066]

[0067] In the formula, W i-1 (1) α′ is the width of the steel plate in the (i-1)th pass after width reduction, in mm; α′ is the width-to-thickness ratio sensitivity coefficient during the free width expansion process after width reduction; β′ is the contact arc length sensitivity coefficient after width reduction; γ′ is the roll diameter sensitivity coefficient after width reduction.

[0068] Step 7.2: Calculate the recovery amount of the dog bone after width reduction and flat roll rolling;

[0069] ΔBD i =e (ω×ξ×λ×ζ) ×ΔB decre_i ×Coff recov

[0070]

[0071] In the formula, R Eω is the vertical roll radius of the rolling mill, in mm; ξ is the width reduction ratio sensitivity coefficient; ξ is the vertical roll diameter sensitivity coefficient; λ is the width reduction amount sensitivity coefficient; ζ is the width variation sensitivity coefficient; a0, a1, a2, a3, a4 are the second fitting coefficients, with a0 ranging from -1.95 to -1.76; a1 ranging from 0.05 to 0.07; a2 ranging from 0.3 to 0.55; a3 ranging from 1.1 to 0.87; and a4 ranging from 6.5 to 8.5.

[0072] Step 8: Based on the sum of the dog-bone recovery amount and free width expansion amount after each pass of flat roll rolling, the new width reduction amount for each pass and the set values ​​for the width of the steel plate after width reduction for each pass are as follows:

[0073] Step 8.1: Calculate the total free spread and dogbone recovery value for each passage. The calculation formula is as follows:

[0074]

[0075] Step 8.2: Calculate the new width reduction for each track using the following formula:

[0076] ΔB′ decre_i =(ΔB) decre -ΔB′ sprd )×Dist i

[0077] Step 8.3: Calculate the set value of the steel plate width for each pass after the width reduction according to the following formula:

[0078] W i (2) =W i-1 (1) +ΔB i -ΔB′ decre_i

[0079] Among them, W i (2) This is the set value for the width of the steel plate in the i-th pass after the width reduction.

[0080] Step 9: Based on the set values ​​of the steel plate width for each pass, calculate the vertical roll opening control values ​​for the rolling width control process for each pass, specifically:

[0081] The vertical roll opening control value for each rolling width control process is calculated using the following formula:

[0082]

[0083] In the formula, E i This is the vertical roll opening control value for the i-th pass, in mm; F iIt is the vertical rolling force of the i-th pass, kN; M i It is the stiffness of the vertical roller in the i-th pass, in kN / mm.

[0084] The calculated vertical roll opening control value is sent from the process control model system (L2) to the basic automation system (L1). The L1 system controls the hydraulic pressing system to drive the vertical roll to the set vertical roll opening control value.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for width control in a hot continuous rolling roughing and cross-rolling process, characterized in that, include: Step 1: Determine the billet parameters, product parameters, roll parameters, and process parameters; Step 2: Heat the continuous casting billet to 1180~1220℃, and the average temperature difference of the continuous casting billet during the cross rolling process is <20℃; Step 3: Calculate the reduction of the flat rolls for each pass of the roughing mill double stand, and calculate the rolling temperature for each pass based on the reduction. Specifically: Step 3.1: The roughing rolling process adopts a two-stand 3+3 pass rolling model. Calculate the reduction of the flat rolls in each pass of the roughing rolling two-stand model. The calculation formula is as follows: In the formula, It is the reduction amount for the i-th pass, in mm; It is the thickness of the (i-1)th pass, in mm; It is the reduction rate of the i-th pass; Step 3.2: Calculate the exit thickness of each pass in the roughing mill. The calculation formula is as follows: In the formula, It represents the thickness of the i-th pass, in mm; Step 3.3: Calculate the rolling temperature for each pass. The calculation formula is as follows: In the formula, It is the rolling temperature of the i-th pass. It is the rolling temperature of the (i-1)th pass, in °C; It is the rolling time of the i-th steel plate, in seconds; Step 4: Calculate the free width expansion for each pass based on the reduction amount and rolling temperature, and obtain the total free width expansion and the width value after expansion, specifically as follows: Step 4.1: Calculate the free width extension and width value for each track. The calculation formula is as follows: In the formula, It is the width free expansion amount of the i-th pass; It is the width of the steel plate in the i-th pass. It is the width of the steel plate in the (i-1)th pass, in mm; It is the broadened model adjustment factor for different temperature changes; The free spread coefficient of the previous steel plate ranges from 0.8 to 1.2; α is the width-to-thickness ratio sensitivity coefficient during the free spread process; β is the contact arc length sensitivity coefficient. γ is a coefficient of performance for measuring roll diameter; These are the first fitting coefficients. The value range is -1.8 to -1.

5. The value range is 0.3 to 0.

4. The value range is 0.01 to 0.

02. The value range is 0.01~0.02; R is the radius of the working roll of the rolling mill, in mm; Step 4.2: Calculate the total free width and the width after expansion. The calculation formula is as follows: In the formula, This is the total free stretch, in mm; This refers to the width of the billet, in mm. This is the width value after expansion, in mm; Step 5: Based on the width value after widening, the target width of the product, and the free widening amount, calculate the total width reduction of the vertical rolls of the roughing mill, the width reduction of each pass, and the width of the steel plate after widening. Step 6: Based on the steel grade, width, dogbone recovery width extension coefficient, and free width extension coefficient of the previous rolled steel plate, determine the free width extension coefficient and dogbone recovery width extension coefficient of the current steel plate during cross rolling; Step 7: Calculate the free width expansion and dog bone recovery amount after flat roll rolling based on the width reduction amount of each pass; Step 8: Based on the sum of the dog bone recovery amount and free width expansion amount after each pass of flat roll rolling, set the new width reduction amount for each pass and the set value of the width of the steel plate after width reduction for each pass. Step 9: Calculate the vertical roll opening control value for each pass's rolling width control process based on the set value of the steel plate width for each pass.

2. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 1, characterized in that: The billet parameters include: billet steel grade, chemical composition, billet thickness, billet width, and billet length; Product parameters include: target width for rough rolling, target thickness for rough rolling, and target temperature for rough rolling; Roll parameters include: work roll diameter, vertical roll diameter, vertical roll wear, and vertical roll thermal expansion. The process parameters include: the steel plate inlet speed, the steel plate outlet speed, and the initial rolling temperature of the steel plate entering the roughing mill.

3. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 1, characterized in that, Step 2 specifically involves: The total heating time in the preheating section is 2.2h~2.5h, the time in the soaking section is 1.4h~1.7h, and the total time in the furnace is 3.6h~4.2h.

4. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 1, characterized in that, Step 5 specifically involves: Step 5.1: Calculate the total width reduction of the vertical rolls in the roughing mill. The calculation formula is as follows: In the formula, This is the total width reduction of the vertical rolls in the roughing mill, in mm; This is the target width of the product, in mm; Step 5.2: Calculate the width reduction for each pass, using the following formula: In the formula, It represents the width reduction for the i-th pass, in mm; It is the proportional coefficient for the width reduction of each vertical roll rolling pass, and its value ranges from 0.2 to 0.

3. Step 5.3: Calculate the width of the reduced steel plate. The calculation formula is as follows: in, It is the width of the steel plate after the width reduction, in mm.

5. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 1, characterized in that, Step 6 specifically involves: Step 6.1: Calculate the free width spread coefficient of the current steel plate during cross rolling according to the following formula: in, The deformation resistance of the previous steel plate, in MPa; This represents the deformation resistance of the steel plate during cross-rolling, in MPa. The target width of the previous steel plate, in mm; The target width of the steel plate during cross-rolling, in mm; This is the free width expansion coefficient of the previous steel plate; Step 6.2: Calculate the dogbone recovery coefficient of the current steel plate during cross-rolling according to the following formula: in, The dog bone recovery coefficient of the previous steel plate.

6. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 4, characterized in that, Step 7 specifically involves: Step 7.1: Calculate the free width extension after the width reduction and flat roll rolling; In the formula, It is the width of the steel plate after the width reduction for the (i-1)th pass, in mm; It is the sensitivity coefficient of the width-to-thickness ratio during the free expansion process after the reduction; It is the contact arc length sensitivity coefficient after the reduction; It is the sensitivity coefficient of the roll diameter after the reduction; Step 7.2: Calculate the recovery amount of the dog bone after width reduction and flat roll rolling; In the formula, This refers to the radius of the vertical roll of the rolling mill, in mm. It is the sensitivity coefficient for the width reduction ratio; It is the sensitivity coefficient of the vertical roll diameter; It is the sensitivity coefficient for the reduction amount; It is the sensitivity coefficient to width changes; It is the second fitting coefficient. The value range is -1.95 to -1.76; The value range is 0.05 to 0.07; The value range is 0.3 to 0.55; The value range is 1.1 to 0.87; The value range is 6.5 to 8.

5.

7. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 6, characterized in that, Step 8 specifically involves: Step 8.1: Calculate the total free spread and dogbone recovery value for each passage. The calculation formula is as follows: Step 8.2: Calculate the new width reduction for each track using the following formula: Step 8.3: Calculate the set value of the steel plate width for each pass after the width reduction according to the following formula: in, This is the set value for the width of the steel plate in the i-th pass after the width reduction.

8. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 7, characterized in that, Step 9 specifically involves: The vertical roll opening control value for each rolling width control process is calculated using the following formula: In the formula, This is the vertical roller opening control value for the i-th pass, in mm; It is the vertical roll rolling force of the i-th pass, in kN; It is the stiffness of the vertical roller in the i-th pass, in kN / mm.

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