Width control method in cross rolling process of hot continuous rolling and rough rolling

Abstract

The width control method in the hot continuous rolling and rough rolling cross rolling process comprises the steps that casting blank parameters, product parameters, roller parameters and technological parameters are determined; the rolling reduction of each pass of flat rollers of the rough rolling double racks and the rolling temperature of each pass are calculated; calculating the width free broadening amount of each pass, the total free broadening amount and the width value after broadening; calculating the total width reduction amount of the vertical rolls of the roughing mill unit, the width reduction amount of each pass and the width of the steel plate after width reduction; according to the dog bone recovery broadening coefficient and the free broadening coefficient of the previous rolled steel plate, the free broadening coefficient and the dog bone recovery broadening coefficient of the current steel plate during cross rolling are determined; calculating the free broadening amount and the dog bone recovery amount after the width is reduced and the dog bone is rolled by the flat roll; calculating a new width reduction amount of each pass and a set value of the width of the steel plate in each pass after width reduction; and according to the set value of the steel plate width of each pass, the vertical roll opening degree control value in the rolling width control process of each pass is obtained through calculation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot continuous rolling, and particularly relates to a width control method for cross-rolling in rough rolling of hot continuous rolling. BACKGROUND

[0002] Hot continuous rolling strip products are basic raw materials for high-end products such as national defense, transportation and energy. Although the automation level of the processing process is high, there are still common problems such as poor three-dimensional size control precision and poor plate shape. The width control precision in the hot continuous rolling process is one of the important indicators of the quality of the hot continuous rolling coil, but in the actual production process of the hot continuous rolling, in the cross-rolling process of steel grade switching, thickness switching, width switching and the like, the long-term learning coefficient used in the control model is the corresponding model parameter when the product was produced last time. In the calculation of the rolling schedule setting this time, the equipment conditions, working conditions and rolling states all change, but the model is not adjusted for these changes, resulting in width control deviation. Therefore, a width control method for cross-rolling in hot continuous rolling is urgently needed to ensure the stability and width control precision of the hot continuous rolling strip rolling process. SUMMARY

[0003] To solve the problem of large width control deviation in the cross-rolling process of steel grade switching, thickness switching, width switching and the like in hot continuous rolling, the present application provides a width control method for cross-rolling in rough rolling of hot continuous rolling.

[0004] The width control method for cross-rolling in rough rolling of hot continuous rolling provided by the present application comprises the following steps:

[0005] Step 1: determine the casting blank parameters, product parameters, roll parameters and process parameters;

[0006] Step 2: heat the continuous casting blank to 1180-1220℃, and the average temperature difference of the continuous casting blank in the cross-rolling process is less than 20℃;

[0007] Step 3: calculate the reduction amount of each pass of the rough rolling double-stand flat roll, and calculate the rolling temperature of each pass according to the reduction amount;

[0008] Step 4: calculate the width free spread amount of each pass according to the reduction amount and the rolling temperature, and obtain the total free spread amount and the width value after width spread;

[0009] Step 5: calculate the total reduction amount of the rough rolling stand, the reduction amount of each pass and the steel plate width after reduction according to the width value after width spread, the target width of the product and the free spread amount;

[0010] Step 6: determine the free spread coefficient and the dog bone recovery spread coefficient of the current steel plate in cross-rolling according to the steel grade, the width, the dog bone recovery spread coefficient and the free spread coefficient of the last rolled steel plate;

[0011] Step 7: According to the width reduction amount of each pass, the free spread amount and dog bone recovery amount after the flat roller rolling are calculated;

[0012] Step 8: According to the sum of the free spread amount and dog bone recovery amount after the flat roller rolling of each pass, the new width reduction amount of each pass and the set value of the width of each pass after the width reduction;

[0013] Step 9: According to the set value of the width of each pass, the edger opening control value of the rolling width control process of each pass is calculated.

[0014] The width control method for the hot continuous rolling rough rolling cross rolling process solves the problem of low width control precision when the steel grade is switched or the specification is switched in the hot continuous rolling rough rolling process. Meanwhile, the width spread model adjustment factor at different temperature changes is given, the free spread and dog bone recovery correction factors when the strength of the steel grade and the specification change are quantified, and the rough rolling edger opening setting value meeting the production and quality requirements is reasonably calculated. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The flow chart of the width control method for the hot continuous rolling rough rolling cross rolling process of the application; DETAILED DESCRIPTION

[0016] As shown in the drawings, the width control method for the hot continuous rolling rough rolling cross rolling process of the application comprises: Figure 1

[0017] Step 1: Determine the casting blank parameters, product parameters, roller parameters and process parameters.

[0018] The casting blank parameters include: blank steel grade, chemical composition, blank thickness, blank width and blank length.

[0019] The product parameters include: rough rolling target width, rough rolling target thickness and rough rolling target temperature.

[0020] The roller parameters include: work roll diameter, edger diameter, edger wear amount and edger thermal expansion amount.

[0021] The process parameters include: steel plate inlet speed, steel plate outlet speed and steel plate opening temperature entering the rough rolling mill train.

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

[0023] ​In the embodiment, the billet thickness is 210 mm, the billet width is 1250 mm, and the billet length is 9000 mm. The rough rolling target thickness is 30 mm, the rough rolling target width is 1200 mm, and the rough rolling target temperature is 1050℃. The R1 and R2 work roll diameters are 1200 mm, the edger roll diameter is 1150 mm, the edger roll wear is 0 mm, and the edger roll thermal expansion is 0.1 mm. The steel plate inlet speed and outlet speed are both 2 mm / s, and the steel plate opening temperature entering the rough rolling mill is 1180℃.

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

[0025] In the embodiment, the total preheating time is 2.2-2.5 h, the soaking time is 1.4-1.7 h, and the total furnace time is 3.6-4.2 h.

[0026] Step 3: calculate the reduction of each pass of the rough rolling double stand, and calculate the rolling temperature of each pass according to the reduction, specifically as follows:

[0027] Step 3.1: the rough rolling process adopts a double stand 3+3 pass rolling model, the reduction of each pass of the rough rolling double stand is calculated, and the calculation formula is as follows:

[0028] Δh i = h i-1 × ε i

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

[0030] Step 3.2: calculate the outlet thickness of each pass of the rough rolling, and the calculation formula is as follows:

[0031] h i = h i-1 - Δh i

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

[0033] Step 3.3: calculate the rolling temperature of each pass, and the calculation formula is as follows:

[0034]

[0035] In the formula, T i is the rolling temperature of the i-th pass, and T i-1is the rolling temperature of the i-1th pass, unit ℃; t i is the rolling time of the steel plate of the i th pass, unit s.

[0036] Pass 1 2 3 4 5 6 Entry thickness (mm) 210 160 122.9 89.1 68 45 Exit thickness (mm) 160 122.9 89.1 68 45 30 Reduction (mm) 50 37.1 33.8 21.1 23 15 Relative reduction (%) 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 width free spread of each pass according to the reduction and rolling temperature, and obtain the total free spread and the width value after spreading, which is specifically as follows:

[0038] Step 4.1: Calculate the width free spread of each pass and the width value, and 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 is the width free spread of the i th pass, unit mm; W i is the width of the steel plate of the i th pass, unit mm; W i-1 is the width of the steel plate of the i-1th pass, unit mm; ψ i is the width spread model adjustment factor at different temperature changes; Coff spread_0 is the free spread coefficient of the last steel plate, and the value range is 0.8-1.2; α is the width-thickness ratio sensitive coefficient of the free spread process; β is the contact arc length sensitive coefficient; γ is the roller diameter sensitive; b0, b1, b2, b3 are the first fitting coefficients, b0 The value range is -1.8-1.5, b1 The value range is 0.3-0.4, b2 The value range is 0.01-0.02, b3 The value range is 0.01-0.02; R is the radius of the flat roller of the rolling mill, unit mm.

[0043] Step 4.2: Calculate the total free spread and the width value after spreading, and the calculation formula is as follows:

[0044]

[0045] W sprd = W slb + ΔB sprd

[0046] In the formula, ΔB sprd is the total free spread, unit mm; W slbis the blank width, unit: mm; W sprd is the spread width value, unit: mm.

[0047] Step 5: According to the spread width value, the target width of the product and the free spread amount, the total width reduction amount of the rough rolling mill group, the width reduction amount of each pass and the steel plate width after width reduction are calculated, which is specifically:

[0048] Step 5.1: The total width reduction amount of the rough rolling mill group is calculated, and the calculation formula is as follows:

[0049] ΔB decre = W sprd - W prod

[0050] In the formula, ΔB decre is the total width reduction amount of the rough rolling mill group, unit: mm; W prod is the target width of the product, unit: mm.

[0051] Step 5.2: The width reduction amount of each pass is calculated, and the calculation formula is as follows:

[0052] ΔB decre_i = ΔB decre × Dist i

[0053] In the formula, ΔB decre_i is the width reduction amount of the i-th pass, unit: mm; Dist i is the width reduction amount distribution proportion coefficient of each stand roll rolling pass, and the value range is 0.2-0.3.

[0054] Step 5.3: The steel plate width after width reduction is calculated, and the calculation formula is as follows:

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

[0056] In which, W i (1) is the steel plate width after width reduction of the i-th pass, unit: mm.

[0057] Step 6: According to the steel grade, width, dog bone recovery spread coefficient and free spread coefficient of the last rolling steel plate, the free spread coefficient and dog bone recovery spread coefficient of the current steel plate during cross rolling are determined, which is specifically:

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

[0059]

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

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

[0062]

[0063] wherein Coff recov_0 is the dog-bone recovery coefficient of the previous steel sheet.

[0064] Step 7: Calculate the free spread amount and dog-bone recovery amount after the flat-rolling after the width reduction according to the width reduction amount of each pass, specifically:

[0065] Step 7.1: Calculate the free spread amount after the flat-rolling after the width reduction;

[0066]

[0067] wherein W i-1 (1) is the width of the steel sheet after the width reduction of the i-1 pass, in mm; a' is the free spread process width-thickness ratio sensitivity coefficient after the width reduction; b' is the contact arc length sensitivity coefficient after the width reduction; g' is the roll diameter sensitivity coefficient after the width reduction.

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

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

[0070]

[0071] wherein R Eis the roll radius of the edger stand, mm; ω is the reduction ratio sensitive coefficient; ξ is the roll diameter sensitive coefficient of the edger stand; λ is the reduction amount sensitive coefficient; ζ is the width change sensitive coefficient; a0, a1, a2, a3, and a4 are the second fitting coefficients, the value range of a0 is -1.95 to -1.76; the value range of a1 is 0.05 to 0.07; the value range of a2 is 0.3 to 0.55; the value range of a3 is 1.1 to 0.87; and the value range of a4 is 6.5 to 8.5.

[0072] Step 8: according to the sum of the dog bone recovery amount and the free spread amount after the flat roll rolling of each pass, the new reduction amount of each pass and the set value of the steel plate width after reduction of each pass, specifically as follows:

[0073] Step 8.1: the total free spread amount and the dog bone recovery value of each pass are calculated, and the calculation formula is as follows:

[0074]

[0075] Step 8.2: the new reduction amount of each pass is calculated according to the following formula:

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

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

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

[0079] Wherein, W i (2) is the set value of the steel plate width after reduction of the i-th pass.

[0080] Step 9: according to the set value of the steel plate width of each pass, the edger roll opening control value of the rolling width control process of each pass is calculated, specifically as follows:

[0081] The edger roll opening control value of the rolling width control process of each pass is calculated according to the following formula:

[0082]

[0083] In the formula, E i is the edger roll opening control value of the i-th pass, unit: mm; F iis the rolling force of the i-th pass, kN; M i is the stiffness of the i-th pass, kN / mm.

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

[0085] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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 in each pass of the roughing mill double stand, and calculate the rolling temperature of each pass based on the reduction. 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. 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 to 2.5h, the time in the soaking section is 1.4h to 1.7h, and the total time in the furnace is 3.6h to 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 3 specifically involves: 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: Δh i =h i-1 ×ε i 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; Step 3.2: Calculate the exit thickness of each pass in the roughing mill. The calculation formula is as follows: h i =h i-1 -Δh i In the formula, h i 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, T i T is the rolling temperature of the i-th pass. i-1 t 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.

5. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 4, characterized in that, Step 4 specifically involves: Step 4.1: Calculate the free width extension and width value for each track. The calculation formula is as follows: ψ i =1.0+(800.0-T i )×0.00148 W i =W i-1 +ΔB i In the formula, ΔB i W is the width free expansion amount of the i-th pass; i W is the width of the steel plate in the i-th pass. 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 mill's flat roll work roll, in mm. Step 4.2: Calculate the total free width and the width after expansion. The calculation formula is as follows: W sprd =W slb +ΔB sprd In the formula, ΔB sprd This is the total free stretch, in mm; W slb This refers to the width of the billet, in mm; W sprd This is the width value after widening, in mm.

6. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 5, 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: ΔB decre =W sprd -W prod 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; Step 5.2: Calculate the width reduction for each pass, using the following formula: ΔB decre_i =ΔB decre ×Dist i 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. Step 5.3: Calculate the width of the reduced steel plate. The calculation formula is as follows: W i (1) =W i-1 +ΔB i -ΔB decre_i Among them, W i (1) It is the width of the steel plate after the width reduction, in mm.

7. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 5, 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: 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 width of the steel plate during cross-rolling, in mm. spread_0 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: Among them, Coff recov_0 The dog bone recovery coefficient of the previous steel plate.

8. The width control method for the hot continuous rolling roughing and cross rolling process according to claim 6, 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, 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 expansion process after width reduction. β′ is the contact arc length sensitivity coefficient after the reduction; γ′ 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; ΔBD i =e (ω×ξ×λ×ζ) ×ΔB decre_i ×Coff recov In the formula, R E ω is the radius of the vertical roll of the rolling mill, in mm; ω is the width reduction ratio sensitivity coefficient. ξ is the sensitivity coefficient for the diameter of the vertical roll; λ is the sensitivity coefficient for width reduction; ζ is the sensitivity coefficient for width change. a0, a1, a2, a3, and a4 are the second fitting coefficients. The value range of a0 is -1.95 to -1.76; the value range of a1 is 0.05 to 0.07; the value range of a2 is 0.3 to 0.55; the value range of a3 is 1.1 to 0.87; and the value range of a4 is 6.5 to 8.

5.

9. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 8, 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: ΔB′ decre_i =(ΔB decre -ΔB′ sprd )×Dist i Step 8.3: Calculate the set value of the steel plate width for each pass after the width reduction according to the following formula: W i (2) =W i-1 (1) +ΔB i -ΔB′ decre_i 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.

10. The width control method for the hot continuous rolling roughing and cross-rolling process according to claim 9, 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, E i This is the vertical roll opening control value for the i-th pass, in mm; F i It is the vertical roll rolling force of the i-th pass, in kN; M i It is the stiffness of the vertical roller in the i-th pass, in kN / mm.

Images