Method for evaluating plate shape quality of finished product in hot rolling leveling process

Abstract

The invention relates to the technical field of steel rolling, and particularly discloses a method for evaluating the plate shape quality of a finished product in a hot-rolling leveling process, which comprises the following steps: (1) dividing hot-rolled strip steel into a head section, a middle section and a tail section; (2) establishing a model according to different specifications (thickness and width intervals) of strip steel, and setting ranges of flattening rolling force and roll bending force; (3) calculating the ratio u (model) of the flattening rolling force / the roll bending force in the model so as to obtain the ratio range f of the flattening rolling force / the roll bending force in the model; (4) after the strip steel passes through the temper mill, according to the temper rolling force and the roll bending force of the temper mill on each section of the strip steel in the actual temper process, the actual ratio u (actual) of the temper rolling force to the roll bending force is calculated; (5) the average rolling force / roll bending force u (average) of the head section, the middle section and the tail section of the strip steel is calculated, u (average) is compared with the ratio range f of the model, if u (average) is within the range f, it is judged that the strip steel is qualified, and otherwise, it is judged that the strip steel is repaired; and (6) repeating the step (4).

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling, in particular to a method for evaluating the quality of finished plate shape in a hot rolling leveling process. Background Art

[0002] Hot rolled strip, especially thin gauge high strength steel, usually adopts leveling process to eliminate or improve the strip shape defects, so that the finished product shape quality meets customer requirements. However, a certain grade of hot rolled online quenched high strength steel with a thickness of 3.5-4mm is concentrated in the same Kaiping line, with a total production of 1031t, of which 224t are downgraded, and the yield rate is only 78.3%, mainly due to edge waves. According to the feedback from the Kaiping line, the unwinding effect of the coils returned to the hot rolling leveling process for repair is good. Due to the limitations of objective factors on site and the high standard shape requirements of customers, the direct contact and non-contact shape measurement equipment that has been maturely applied in the production site cannot meet the requirements of online real-time shape measurement of finished products in the hot rolling leveling process. For this reason, we propose a method to evaluate the shape quality of finished products in the hot rolling leveling process. Summary of the invention

[0003] The purpose of the present invention is to provide a method for evaluating the plate shape quality of the finished product of the hot rolling flattening process, so as to solve the problem raised in the above background technology that due to the limitations of objective factors on site and the high standard plate shape requirements of customers, the direct contact and non-contact plate shape measurement equipment that have been maturely applied in industrial applications on production sites cannot meet the requirements of online real-time plate shape measurement of the finished products of the hot rolling flattening process.

[0004] To achieve the above object, the present invention provides the following technical solution: A method for evaluating the quality of the finished plate shape in a hot rolling flattening process, comprising the following steps:

[0005] (1) Divide the hot-rolled strip into three sections: head, middle and tail;

[0006] (2) According to different strip specifications (thickness and width ranges), a model is established and the ranges of temper rolling force and bending roll force are set;

[0007] (3) calculating the ratio △u(modulus) of the temper rolling force / bending roll force in the model, thereby obtaining the ratio range f of the temper rolling force / bending roll force in the model;

[0008] (4) After the strip passes through the leveler, the actual ratio △u (real) of the leveler rolling force / bending roll force is calculated based on the leveler rolling force and bending roll force of each section of the strip during the actual leveling process;

[0009] (5) Calculate the average rolling force / bending roll force △u (average) of the head, middle and tail sections of the strip, and compare △u (average) with the ratio range f of the model. If △u (average) is within the range f, it is judged to be qualified, otherwise it is judged to be repaired;

[0010] (6) Repeat step (4).

[0011] Among them, the flat rolling force / flat bending roll force is negatively correlated with the yield rate. An important factor in flattening and improving the edge waves of incoming materials is the roll deflection. The greater the rolling force, the greater the deflection. At this time, a greater bending roll force is needed to eliminate the edge waves.

[0012] Among them, the bending roll force of the leveling machine is ±600KN, and the simplified calculation formula can be expressed as: F=a0+a1D+a2f+a3f / D+a4fD, where F represents the bending roll force, f represents the rolling force per unit area, D represents the strip width, and a0 to a4 are coefficients.

[0013] Among them, the ratio range f of the temper rolling force / bending roll force in the model is 8-12.

[0014] Among them, the model is the Bland-Ford model. Since the hot-rolled strip is divided into three sections: head, middle and tail, let P1 be the rolling pressure per unit width in the head section of the strip, P2 be the rolling pressure per unit width in the middle section of the strip, P3 be the rolling pressure per unit width in the tail section of the strip, P0 be the total rolling pressure per unit width, P0=P1+P2+P3, and the calculation of rolling pressure conforms to the Bland-Ford formula.

[0015] Among them, a0 to a4 are empirical coefficients or adjustment coefficients. These coefficients are used to reflect the influence of different factors on the bending roll force and help adjust the bending roll force to achieve the required plate shape quality. The values ​​of these coefficients are adjusted according to the actual situation on site. The specific process is as follows:

[0016] (1) Understand the relationship between bending roll force and parameters such as strip width D and unit area rolling force f through theoretical analysis;

[0017] (2) Using empirical data from similar rolling mills and process conditions, preliminarily set the coefficient values ​​of a0 to a4;

[0018] (3) Carry out a series of rolling tests with different parameter combinations on the rolling mill, and record the strip width D, the rolling force per unit area a, and the actual measured bending roll force F in each test;

[0019] (4) Use statistical methods and data analysis software (such as SPSS, Excel, etc.) to perform regression analysis on the test data to determine the optimal values ​​of a0 to a4;

[0020] (5) After determining the coefficient value, conduct a verification test to confirm whether the new coefficient value is accurate;

[0021] (6) Based on the verification test results, the coefficient value is further optimized to improve the prediction accuracy of the bending roll force and the plate shape quality;

[0022] (7) The optimized coefficient values ​​are saved in the control system of the rolling mill for application in actual production.

[0023] The goal of the regression analysis is to minimize the error between the predicted bending roll force and the actual bending roll force.

[0024] The present invention has at least the following beneficial effects:

[0025] According to the flattening rolling force and bending roll force of the flattening machine on each section of the strip during the actual flattening process, the actual ratio of the flattening rolling force / bending roll force △u (real) is calculated, and the calculated average rolling force / bending roll force △u (average) is compared with the ratio range f of the model. Since the flattening rolling force / flattening bending roll force is negatively correlated with the yield rate, the yield rate of the strip can be quickly judged by comparing △u (average) with the ratio range f of the established model. This is to control the yield rate of the plate when flattening a large number of strips, quickly evaluate the plate shape quality of the finished product in the hot rolling flattening process, and improve the plate production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a method for evaluating the quality of finished plate shape in a hot rolling skin-pass process;

[0027] Figure 2 A line graph showing the relationship between the yield rate and the temper rolling force / temper bending roll force of the present invention;

[0028] Figure 3 It is a line graph of the yield rate and the temper rolling force / bending roll force of the present invention; DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figures 1 to 3 The present invention provides a technical solution: a method for evaluating the quality of the finished plate shape in a hot rolling flattening process, comprising the following steps:

[0031] (1) Divide the hot-rolled strip into three sections: head, middle and tail;

[0032] (2) According to different strip specifications (thickness and width ranges), a model is established and the ranges of temper rolling force and bending roll force are set;

[0033] (3) calculating the ratio △u(modulus) of the temper rolling force / bending roll force in the model, thereby obtaining the ratio range f of the temper rolling force / bending roll force in the model;

[0034] (4) After the strip passes through the leveler, the actual ratio △u (real) of the leveler rolling force / bending roll force is calculated based on the leveler rolling force and bending roll force of each section of the strip during the actual leveling process;

[0035] (5) Calculate the average rolling force / bending roll force △u (average) of the head, middle and tail sections of the strip, and compare △u (average) with the ratio range f of the model. If △u (average) is within the range f, it is judged to be qualified, otherwise it is judged to be repaired;

[0036] (6) Repeat step (4).

[0037] The flat rolling force / flat bending roll force is negatively correlated with the yield rate. An important factor in flattening and improving the edge waves of incoming materials is the roll deflection. The greater the rolling force, the greater the deflection. At this time, a greater bending roll force is needed to eliminate the edge waves.

[0038] The bending roll force of the leveling machine is ±600KN, and the simplified calculation formula can be expressed as: F=a0+a1D+a2f+a3f / D+a4fD, where F represents the bending roll force, f represents the rolling force per unit area, D represents the strip width, and a0 to a4 are coefficients.

[0039] The ratio f of the temper rolling force / bending roll force in the model ranges from 8 to 12.

[0040] The model is the Bland-Ford model. Since the hot-rolled strip is divided into three sections: head, middle and tail, let P1 be the rolling pressure per unit width in the head section of the strip, P2 be the rolling pressure per unit width in the middle section of the strip, P3 be the rolling pressure per unit width in the tail section of the strip, and P0 be the total rolling pressure per unit width. P0 = P1 + P2 + P3. The calculation of rolling pressure conforms to the Bland-Ford formula, as follows:

[0041] Rolling pressure per unit width in the strip head area P1:

[0042] P1={(1-γ2h0) / 4}*√{(R / △h)*(K-σ0)2 / E};

[0043] Rolling pressure per unit width in the middle section of the strip P2:

[0044] P2=K*√(R*△h)*(1-σ0 / K)*fp(a, b, ε);

[0045] Rolling pressure per unit width in the tail section of the strip P2:

[0046] P3=2 / 3*(K-σ1)^(3 / 2)*√{R*h1*(1-γ2) / E};

[0047] a=μ√(R / h1);

[0048] b=(1-σ1 / K) / (1-σ0 / K), is the tension factor;

[0049] In the formula, h0 is the thickness of the first strip;

[0050] h1--the thickness of the tail strip;

[0051] △h--strip reduction;

[0052] Ε--strip reduction rate;

[0053] γ--Bossan coefficient of the strip;

[0054] E--elastic modulus of the strip;

[0055] K--Average deformation resistance of the strip;

[0056] σ0--after tension;

[0057] σ1--front tension;

[0058] μ--friction coefficient;

[0059] R--Elastic flattening radius of the roller.

[0060] a0 to a4 are empirical coefficients or adjustment coefficients. These coefficients are used to reflect the influence of different factors on the bending roll force and help adjust the bending roll force to achieve the required plate quality. The values ​​of these coefficients are adjusted according to the actual situation on site. The specific process is as follows:

[0061] (1) Understand the relationship between bending roll force and parameters such as strip width D and unit area rolling force f through theoretical analysis;

[0062] (2) Using empirical data from similar rolling mills and process conditions, preliminarily set the coefficient values ​​of a0 to a4;

[0063] (3) Carry out a series of rolling tests with different parameter combinations on the rolling mill, and record the strip width D, the rolling force per unit area a, and the actual measured bending roll force F in each test;

[0064] (4) Use statistical methods and data analysis software (such as SPSS, Excel, etc.) to perform regression analysis on the test data to determine the optimal values ​​of a0 to a4;

[0065] (5) After determining the coefficient value, conduct a verification test to confirm whether the new coefficient value is accurate;

[0066] (6) Based on the verification test results, the coefficient value is further optimized to improve the prediction accuracy of the bending roll force and the plate shape quality;

[0067] (7) The optimized coefficient values ​​are saved in the control system of the rolling mill for application in actual production.

[0068] The goal of the regression analysis is to minimize the error between the predicted and actual roll bending forces.

[0069] The present application calculates the actual ratio △u(real) of the flattening rolling force / bending roll force according to the flattening rolling force and bending roll force of the flattening machine on each section of the strip during the actual flattening process, and compares the calculated average rolling force / bending roll force △u(average) with the ratio range f of the model. Since the flattening rolling force / flattening bending roll force is negatively correlated with the yield rate, the yield rate of the strip can be quickly determined by comparing △u(average) with the ratio range f of the established model, so as to control the yield rate of the plate when flattening a large number of strips, quickly evaluate the plate shape quality of the finished product in the hot rolling flattening process, and improve the plate production efficiency.

[0070] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0071] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the quality of finished plate shape in a hot rolling flattening process, characterized in that: The following steps are involved: (1) Divide the hot-rolled strip into three sections: head, middle and tail; (2) According to different strip specifications (thickness and width ranges), a model is established and the ranges of temper rolling force and bending roll force are set; (3) calculating the ratio △u(modulus) of the temper rolling force / bending roll force in the model, thereby obtaining the ratio range f of the temper rolling force / bending roll force in the model; (4) After the strip passes through the leveler, the actual ratio △u (real) of the leveler rolling force / bending roll force is calculated based on the leveler rolling force and bending roll force of each section of the strip during the actual leveling process; (5) Calculate the average rolling force / bending roll force △u (average) of the head, middle and tail sections of the strip, and compare △u (average) with the ratio range f of the model. If △u (average) is within the range f, it is judged to be qualified, otherwise it is judged to be repaired; (6) Repeat step (4).

2. The method for evaluating the quality of the finished plate shape in the hot rolling skin-pass process according to claim 1, characterized in that: The flat rolling force / flat bending roll force is negatively correlated with the yield rate. An important factor in flattening and improving the edge waves of incoming materials is the roll deflection. The greater the rolling force, the greater the deflection. At this time, a greater bending roll force is needed to eliminate the edge waves.

3. The method for evaluating the quality of the finished plate shape in the hot rolling and leveling process according to claim 1, characterized in that: The bending roll force of the leveling machine is ±600KN, and the simplified calculation formula can be expressed as: F=a0+a1D+a2f+a3f / D+a4fD, where F represents the bending roll force, f represents the rolling force per unit area, D represents the strip width, and a0 to a4 are coefficients.

4. The method for evaluating the quality of the finished plate shape in the hot rolling skin-pass process according to claim 1, characterized in that: The ratio f of the temper rolling force / bending roll force in the model ranges from 8 to 12.

5. The method for evaluating the quality of the finished plate shape in the hot rolling skin-pass process according to claim 1, characterized in that: The model is a Bland-Ford model. Since the hot-rolled strip is divided into three sections: head, middle and tail, P1 is the rolling pressure per unit width in the head section of the strip, P2 is the rolling pressure per unit width in the middle section of the strip, P3 is the rolling pressure per unit width in the tail section of the strip, P0 is the total rolling pressure per unit width, P0=P1+P2+P3, and the calculation of rolling pressure conforms to the Bland-Ford formula.

6. The method for evaluating the quality of the finished plate shape in the hot rolling skin-pass process according to claim 3, characterized in that: The a0 to a4 are empirical coefficients or adjustment coefficients. These coefficients are used to reflect the influence of different factors on the bending roll force and help adjust the bending roll force to achieve the required plate shape quality. The values ​​of these coefficients are adjusted according to the actual situation on site. The specific process is as follows: (1) Understand the relationship between bending roll force and parameters such as strip width D and unit area rolling force f through theoretical analysis; (2) Using empirical data from similar rolling mills and process conditions, preliminarily set the coefficient values ​​of a0 to a4; (3) Carry out a series of rolling tests with different parameter combinations on the rolling mill, and record the strip width D, the rolling force per unit area a, and the actual measured bending roll force F in each test; (4) Use statistical methods and data analysis software (such as SPSS, Excel, etc.) to perform regression analysis on the test data to determine the optimal values ​​of a0 to a4; (5) After determining the coefficient value, conduct a verification test to confirm whether the new coefficient value is accurate; (6) Based on the verification test results, the coefficient value is further optimized to improve the prediction accuracy of the bending roll force and the plate shape quality; (7) The optimized coefficient values ​​are saved in the control system of the rolling mill for application in actual production.

7. The method for evaluating the quality of the finished plate shape in the hot rolling skin-pass process according to claim 6, characterized in that: The goal of the regression analysis is to minimize the error between the predicted roll bending force and the actual roll bending force.

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