Method for improving no-load roll gap shape adjusting capacity

Abstract

The invention relates to the field of strip steel production, in particular to a method for improving the no-load roll gap shape adjusting capacity, a roll gap curve distribution shape is simulated and calculated by adopting a distribution function value Cwax of a roll axial roll type and a distribution function value Cwrx of a roll radial roll type, and the no-load roll gap shape is obtained by adjusting roll bending force and changing a wear curve in the rolling process. And completing optimization of the online roller type curve distribution form. The method has the advantages that in the middle and later periods of production of a finishing mill group, limitation of roller replacement time, frequency and variety specifications is reduced, the conventional working rollers in the primary, secondary and multiple square roller shapes are adopted according to the arrangement forms of different rolling mills, and the working rollers are changed in a long-stroke axial periodic movement mode or an on-line cross change roller gap shape. Abrasion of the roller at different points is homogenized, meanwhile, a working roller bending system is matched, the roller shape curve and the roller gap shape change tend to be consistent, and equal-proportion convexity change is achieved so as to control the wave shape and the convexity of the strip steel.

Description

Technical Field

[0001] The invention relates to the field of strip steel production, and in particular to a method for improving the ability to adjust the shape of an unloaded roll gap. Background Art

[0002] In the production of hot-rolled strip steel, the process parameters in the rolling process are reasonably set, especially the reasonable proportional distribution of the pressing load of the finishing mill, including the proportional configuration of the rolling force and the roll gap, which is used to optimize the roll crown change curve and improve the meshing degree of the upper and lower roll gap shapes, thereby improving the control accuracy of the finished product crown and plate shape. Aiming at the main factors affecting the working roll bearing roll gap shape in the rolling process, such as temperature, rolling force, bending roll force, original roll shape of the working roll, worn roll shape of the working roll, original roll shape of the support roll, worn roll shape of the support roll, strip width, thickness, hardness, etc., multivariate means are used to combine and calculate the influencing factors affecting the roll gap shape. Based on the multivariate calculation results, the model coefficients are calculated online by the nonlinear regression method. However, in actual detection, it is found that the cross-sectional shape condition is still not optimistic, and there are still deficiencies in reaching the upper limit of the adjustment ability, as follows:

[0003] 1) The hot rolling finishing mill has serious and uneven roller wear, resulting in asymmetric or zigzag distribution of box holes, with large differences between local high and low points. In terms of the horizontal direction, the plate shape refers to the cross-sectional shape of the plate, that is, the thickness distribution curve in the width direction of the steel plate, including a series of concepts such as plate convexity and local high points. Among them, plate convexity is the most commonly used representative indicator of horizontal plate shape. Therefore, the unit is very sensitive to the repeated jumps and changes in width, which limits production efficiency and results in the inability to fully utilize the capacity of the finishing mill; realizing online prediction of the hot roller shape of the roller is one of the main difficulties in plate shape control.

[0004] 2) When the plate width is certain, the unit deformation difference between the center and the edge of the plate will lead to insufficient thinning ability of the edge of the plate and strip. In terms of longitudinal direction, it usually refers to the straightness, or warping, commonly known as wave shape, that is, the flatness along the length of the plate and strip, especially at the 1 / 3 to 1 / 4 distance from the center to the edge. It is particularly obvious, indicating that the shape of the roll gap changes after a period of rolling, and the control of the edge of the steel plate is weakened. In particular, the wear of the roll not only increases the roll consumption, but also changes the distribution of the roll type, affecting the precise control of the plate shape and plate convexity of the rolled piece, which will aggravate the edge thinning and poor plate shape of thin plate rolling, reduce the yield rate, and make it difficult to control the plate shape when rolling wide, thin, and hard special steels. In hot rolling production, as the rolling process proceeds, the strip becomes thinner and thinner, not only the size of the strip changes, but also the longitudinal extension deformation of the strip changes accordingly, that is, the strip shape changes. Summary of the invention

[0005] The object of the present invention is to provide a method for improving the regulating ability of the no-load roll gap shape, eliminating or reducing the influence of roll wear, rolling force fluctuations, and roll temperature changes on the control of edge waves and crown, improving the edge thinning control performance of the rolling mill, improving the overall, transverse, and longitudinal flatness quality of the hot-rolled strip steel, reducing the occurrence probability of quality accidents such as local high points and waves, and improving the production efficiency of the unit.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A method for improving the regulating ability of the no-load roll gap shape, using the distribution function value Cwax of the roll axial roll profile and the distribution function value Cwrx of the roll radial roll profile to describe the roll profile distribution condition of the roll during the rolling process, simulating and calculating the distribution shape of the roll gap curve, and completing the optimization of the online roll profile curve distribution form by adjusting the bending roll force and changing the wear curve during the rolling process, specifically including:

[0008] S1. Bending roll force coefficient calculation model;

[0009] S2. Strip crown model at the exit between stands;

[0010] S3. Strip flatness model at the exit between stands.

[0011] In S1, for the bending roll force coefficient calculation model, according to the main factors affecting the crown of the bearing roll gap, a multi-variable method is used to calculate the working condition combination. Based on the finite element calculation results, the model coefficients are obtained through the multi-variable non-linear regression method. The online calculation formula is as follows:

[0012]

[0013] In formula ①, Mcwax represents the working roll axial influence coefficient; Mcwrx represents the working roll radial influence coefficient; Mcbax represents the backup roll axial influence coefficient; Mcbrx represents the backup roll radial influence coefficient; MRf represents the rolling force influence coefficient; MEf represents the bending roll force influence coefficient; Rf represents the rolling force; Ef represents the bending roll force; Cwax represents the working roll axial roll profile distribution; Cwrx represents the working roll radial roll profile distribution; Cbax represents the backup roll axial roll profile distribution; Cbrx represents the backup roll radial roll profile distribution; Dw represents the working roll diameter; Db represents the backup roll diameter; W represents the strip width; Cr represents the initial roll shape of the working roll.

[0014] It also includes the inter-stand target crown and flatness control. The inter-stand target crown and flatness control means that the shape of the strip crown between stands changes following the change of the roll gap shape. The inter-stand target crown is the shape of the strip crown between adjacent stands, and the flatness is within 1 / 4 of the difference between the strip crown and the strip camber.

[0015] In S2, the strip crown model at the inter-stand outlet has the following calculation formula:

[0016]

[0017] In Formula ②, Chi represents the crown at the outlet of the i-th stand; MRf represents the rolling force influence coefficient; Rf represents the rolling force; MEf represents the work roll bending force influence coefficient; Ef represents the work roll bending force; Mcwax represents the work roll axial influence coefficient; Mcbax represents the backup roll axial influence coefficient; λw represents the strip width influence coefficient; Cwrli represents the original roll profile of the work roll; Cww represents the worn roll profile of the work roll; Cwh represents the thermally expanded roll profile of the work roll; Mcbax represents the backup roll axial influence coefficient; Mcbrx represents the backup roll radial influence coefficient; Cbr represents the original roll profile of the backup roll; Cbw represents the worn roll profile of the backup roll; Cbh represents the thermally expanded roll profile of the backup roll; ψ represents the flatness model coefficient; represents the mechanical crown of the bearing roll gap; hi represents the outlet thickness of the i-th stand; Hi represents the inlet thickness of the i-th stand; Ch(i-1) represents the crown at the outlet of the previous stand.

[0018] In S3, the strip flatness model at the inter-stand outlet has the following calculation formula:

[0019] ψi = λm * (ψi-1 + Chi-1 / hi-1 - Chi / hi) * § * ω * ￡ ③

[0020] In Formula ③, ψi represents the flatness model coefficient of the i-th stand; λm represents the strip width coefficient; Chi-1 represents the crown at the outlet of the previous stand of the i-th stand; hi-1 represents the outlet thickness of the previous stand of the i-th stand; Chi represents the crown at the outlet of the i-th stand: hi represents the outlet thickness of the i-th stand; § represents the strip shape change coefficient; ω represents the strip shape inheritance coefficient; ￡ represents the elongation coefficient.

[0021] The main factors affecting the crown of the bearing roll gap include rolling force, work roll bending force, comprehensive roll profile of the work roll, comprehensive roll profile of the backup roll, and strip width.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. According to the strip shape control strategy of hot-rolled strip steel, in the middle and late stages of the production of the finishing mill, due to severe and extremely uneven wear of the rolls, and at the same time to achieve the goal of increasing the rolling kilometers, reducing the roll changing time and frequency, and the limitations of product specifications, work rolls with conventional first-order, second-order, and multi-order roll profiles are used according to the layout forms of different rolling mills. By using the long-stroke axial periodic shifting of the work roll or the online cross-changing of the roll gap shape, the wear of the rolls at different points is homogenized. At the same time, in cooperation with the work roll bending system, the roll profile curve is kept consistent with the change trend of the roll gap shape, and an equal-proportion crown change is achieved to control the waviness and crown of the strip;

[0024] 2. In order to eliminate or improve and reduce the influence of rolling force, the fluctuation of roll gap, the wear of rolls, and the change of roll temperature on the shape and crown control, and to improve the shape adjustment control ability of the rolling mill, a method and technology for improving the shape adjustment ability of the no-load roll gap used in the finishing mill are developed to improve the shape quality of hot-rolled strip steel, enhance the control ability of edge thinning and local high points, reduce the occurrence probability of on-line quality accidents and potential quality accidents, and improve the operation efficiency.

[0025] 3. The roll not only has the control ability of initial crown and multiple crowns, but also has the control ability of higher-order crowns. From the aspect of changing the influence of the cross-sectional shape change trend of the steel plate, the no-load roll gap adjustment technology of the roll has the ability to change the roll gap distribution shape by changing the roll profile curve to control the crown shape and eliminate complex wave shapes such as two-side waves, middle waves, and local high points.

[0026] 4. Similar to the traditional technology, by changing different working modes of the work roll, the roll gap crown can be significantly changed. At the same time, by setting grinding functions such as different arbitrary plotting curves before the work roll is put into operation, the original roll profile shape is changed, thereby affecting the no-load roll gap shape.

[0027] 5. After a large number of computational simulations and analyzing the coverage of different curves on the load-bearing roll gap adjustment ability and adjustment area, the shape adjustment ability of the no-load roll gap is effectively improved after determining the load-bearing roll gap shape. Description of the Drawings

[0028] Figure 1 It is an equivalent representation of the comprehensive roll profile of the work roll. Detailed Embodiment

[0029] The present invention will be described in detail below with reference to the accompanying drawings of the specification. However, it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0030] The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The methods used in the following embodiments are all conventional methods unless otherwise specified.

[0031] Embodiment 1

[0032] See Figure 1, A method for improving the ability to adjust the shape of the no-load roll gap. The distribution function value Cwax of the axial roll profile of the roll and the distribution function value Cwrx of the radial roll profile of the roll are used to describe the overall roll profile distribution of the roll during the rolling process, simulate the distribution shape of the full-profile roll gap curve, and achieve the organic combination of the two by intervening and adjusting the bending roll force and changing the wear curve during the rolling process, so as to optimize the online roll profile curve distribution form and improve the ability of the unit to adjust the roll gap shape; the distribution function value Cwax of the axial roll profile of the roll and the distribution function value Cwrx of the radial roll profile of the roll include the required mill load, bending roll force, mechanical equipment, roll thermal expansion, roll wear, and the equivalent parabolic roll profile composed of the original roll profile of the roll, as well as the shape curves composed of the mill transverse stiffness coefficient, elongation coefficient, flatness change coefficient, etc. for comprehensive calculation.

[0033] The axial roll profile curve and the radial roll profile curve of the roll are comprehensively calculated using the equivalent parabolic roll profile composed of the mill load, bending roll force, mechanical equipment, roll thermal expansion, roll wear, and the original roll profile of the roll required for actual crown calculation, as well as the shape curves composed of the mill transverse stiffness coefficient, elongation coefficient, flatness change coefficient, etc.; specifically including:

[0034] S1. Bending roll force coefficient calculation model;

[0035] According to the main factors affecting the crown of the bearing roll gap, the working conditions are calculated using the finite element method. Based on the finite element calculation results, the model coefficients are obtained through the multiple nonlinear regression method. The main factors include rolling force, bending roll force, the comprehensive roll shape of the work roll, the comprehensive roll shape of the backup roll, and strip width; the online calculation formula is as follows:

[0036]

[0037] Mcwax: Axial influence coefficient of the work roll Mcwrx: Radial influence coefficient of the work roll Mcbax: Axial influence coefficient of the backup roll Mcbrx: Radial influence coefficient of the backup roll MRf: Rolling force influence coefficient MEf: Bending roll force influence coefficient Rf: Rolling force Ef: Bending roll force Cwax: Axial roll profile distribution of the work roll Cwrx: Radial roll profile distribution of the work roll Cbax:: Axial roll profile distribution of the backup roll Cbrx: Radial roll profile distribution of the backup roll Dw: Diameter of the work roll Db: Diameter of the backup roll λw: Strip width influence coefficient Cwr: Initial roll shape of the work roll Cbr: Original roll shape of the backup roll.

[0038] S2. The mechanism and control idea of the target crown and flatness calculation model between stands are as follows: Good cross-sectional shape accuracy mainly depends on the roll thermal expansion curve, roll wear model, calculation accuracy of strip crown proportionality, external influence factors, and the improvement of the adaptive function. To ensure the smoothness of the cross-sectional shape curve and the flatness of the surface, the combination setting of the mechanical movement amount and bending roll force of the equipment is carried out. Among them, the calculation of the fitting degree of the axial curve and radial curve of the roll profile is the basis, and the roll gap adjustment ability of each stand is the key. Only when the axial curve and radial curve of the roll profile control wear accurately and the proportional crown distribution of the strip is reasonable can a good flatness be obtained. Keeping the proportional crown constant within the allowable crown control range and correcting the roll gap shape according to the target flatness, improving the fitting degree of the axial curve and radial curve of the roll profile is the key to this link. Only when the roll gap shape is reasonably distributed can the target crown and flatness between stands be good.

[0039] S3. The strip crown model at the stand exit, the calculation formula is as follows:

[0040]

[0041] In formula ②, Chi is the crown at the exit of the i-th stand; MRf is the rolling force influence coefficient, Rf is the rolling force; MEf is the bending roll force influence coefficient, Ef is the bending roll force; Mcwax is the working roll axial influence coefficient; Mcbax is the backup roll axial influence coefficient; λw is the strip width influence coefficient; Cwrli is the original roll profile of the working roll; Cww is the worn roll profile of the working roll; Cwh is the thermally expanded roll profile of the working roll; Mcbax is the backup roll axial influence coefficient; Mcbrx is the backup roll radial influence coefficient; Cbr is the original roll profile of the backup roll; Cbw is the worn roll profile of the backup roll; Cbh is the thermally expanded roll profile of the backup roll; ψ is the flatness model coefficient; is the mechanical crown of the bearing roll gap; hi is the exit thickness of the i-th stand; Hi is the entrance thickness of the i-th stand; Ch(i - 1) is the crown at the exit of the previous stand.

[0042] S4. The strip flatness model at the stand exit, the calculation formula is as follows:

[0043] ψi = λm * (ψi - 1 + Chi - 1 / hi - 1 - Chi / hi) * § * ω * ￡ ③

[0044] In the formula, ψi is the flatness model coefficient of the i-th stand; λm is the strip width coefficient; Chi - 1 is the crown at the exit of the previous stand of the i-th stand; hi - 1 is the exit thickness of the previous stand of the i-th stand; Chi is the crown at the exit of the i-th stand: hi is the exit thickness of the i-th stand; § is the flatness change coefficient; ω is the flatness heredity coefficient; ￡ is the elongation coefficient.

[0045] According to the shape control strategy of hot-rolled strip steel, in the middle and late stages of the production of the finishing mill, due to severe and extremely uneven roll wear, and at the same time to achieve increased rolling kilometers, reduced roll change time and frequency, and variety and specification limitations, work rolls with conventional first-order, second-order, and multi-order roll profiles are used according to the layout forms of different rolling mills. By using the long-stroke axial periodic shifting of the work roll or the online cross-changing of the roll gap shape, the wear of the roll at different points is homogenized. At the same time, in cooperation with the work roll bending system, the roll profile curve is kept consistent with the change trend of the roll gap shape, and an equal-proportion convexity change is achieved to control the waviness and convexity of the strip steel.

[0046] In order to eliminate or improve and reduce the influence of the fluctuations of rolling force, roll gap, roll wear, and roll temperature change on shape and convexity control, and to improve the shape adjustment control ability of the rolling mill, a method for improving the shape adjustment ability of the no-load roll gap used in the finishing mill is developed to improve the shape quality of hot-rolled strip steel, enhance the control ability of edge thinning and local high points, reduce the occurrence probability of online quality accidents and potential quality accidents, and improve the operation efficiency.

[0047] From the aspect of the influence on changing the change trend of the cross-sectional shape of the steel plate, the roll no-load roll gap adjustment technology has the ability to control the convexity shape and eliminate complex waviness such as double-edge waves, middle waves, and local high points by changing the roll profile curve to change the roll gap distribution shape.

[0048] Similar to traditional technologies, by changing different working modes of the work roll, the roll gap convexity can be significantly changed. At the same time, by setting grinding functions such as different arbitrary point curves before the work roll is put into use, the original roll profile shape is changed, thereby affecting the no-load roll gap shape.

[0049] After a large number of computational simulations and analyzing the coverage of different curves on the load-bearing roll gap adjustment ability and adjustment area, the shape adjustment ability of the no-load roll gap is effectively improved after determining the load-bearing roll gap shape.

Claims

1. A method for improving the regulating ability of the no-load roll gap, characterized in that, The distribution function values Cwax of the axial roll profile and Cwrx of the radial roll profile of the roll are used to describe the roll profile distribution condition of the roll during the rolling process, simulate and calculate the distribution shape of the roll gap curve, and complete the optimization of the online roll profile curve distribution form by adjusting the bending roll force and changing the wear curve during the rolling process, specifically including: S1. Bending roll force coefficient calculation model; S2. Strip crown model at the exit between stands; S3. Strip flatness model at the exit between stands.

2. A method for improving the ability to adjust the shape of the no-load roll gap according to claim 1, characterized in that, In S1, for the bending roll force coefficient calculation model, according to the main factors affecting the crown of the bearing roll gap, multiple means are used to calculate the working condition combination, and based on the finite element calculation results, the model coefficients are obtained through the multiple nonlinear regression method. The online calculation formula is as follows: In Formula ①, Mcwax represents the axial influence coefficient of the work roll; Mcwrx represents the radial influence coefficient of the work roll; Mcbax represents the axial influence coefficient of the backup roll; Mcbrx represents the radial influence coefficient of the backup roll; MRf represents the rolling force influence coefficient; MEf represents the bending roll force influence coefficient; Rf represents the rolling force; Ef represents the bending roll force; Cwax represents the axial roll profile distribution of the work roll; Cwrx represents the radial roll profile distribution of the work roll; Cbax represents the axial roll profile distribution of the backup roll; Cbrx represents the radial roll profile distribution of the backup roll; Dw represents the diameter of the work roll; Db represents the diameter of the backup roll; W represents the strip width; Cr represents the initial roll shape of the work roll.

3. A method for improving the ability to adjust the shape of the no-load roll gap according to claim 1, characterized in that, It also includes the control of the target crown and flatness between stands. The control of the target crown and flatness between stands means that the shape of the strip crown between stands changes following the change of the roll gap shape. The target crown between stands is the shape of the strip crown between adjacent stands, and the flatness is within 1 / 4 of the difference between the strip crown and the strip camber.

4. A method for improving the ability to adjust the shape of the no-load roll gap according to claim 1, characterized in that, In S2, for the strip crown model at the exit between stands, the calculation formula is as follows: In Formula ②, Chi represents the crown at the outlet of the i-th stand; MRf represents the rolling force influence coefficient; Rf represents the rolling force; MEf represents the bending force influence coefficient; Ef represents the bending force; Mcwax represents the work roll axial influence coefficient; Mcbax represents the backup roll axial influence coefficient; λw represents the strip width influence coefficient; Cwrli represents the original work roll profile; Cww represents the worn work roll profile; Cwh represents the thermally expanded work roll profile; Mcbax represents the backup roll axial influence coefficient; Mcbrx represents the backup roll radial influence coefficient; Cbr represents the original backup roll profile; Cbw represents the worn backup roll profile; Cbh represents the thermally expanded backup roll profile; ψ represents the flatness model coefficient. represents the mechanical crown of the bearing roll gap; hi represents the outlet thickness of the i-th stand; Hi represents the inlet thickness of the i-th stand; Ch(i-1) represents the crown at the outlet of the previous stand.

5. A method for improving the ability to adjust the shape of the no-load roll gap according to claim 1, characterized in that, In S3, for the strip flatness model at the exit between stands, the calculation formula is as follows: ψi = λm * (ψi - 1 + Chi - 1 / hi - 1 - Chi / hi) * § * ω * ￡ ③ In Formula ③, ψi represents the flatness model coefficient of the i-th stand; λm represents the strip width coefficient; Chi - 1 represents the crown at the exit of the previous stand of the i-th stand; hi - 1 represents the thickness at the exit of the previous stand of the i-th stand; Chi represents the crown at the exit of the i-th stand: hi represents the thickness at the exit of the i-th stand; § represents the strip shape change coefficient; ω represents the strip shape inheritance coefficient; ￡ represents the elongation coefficient.

6. A method for improving the ability to adjust the shape of the no-load roll gap according to claim 2, characterized in that, The main factors affecting the crown of the bearing roll gap include rolling force, bending roll force, comprehensive roll shape of the work roll, comprehensive roll shape of the backup roll, and strip width.

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