Intermediate roller axial force prediction method suitable for pickling rolling unit

Abstract

The invention discloses a middle roller axial force prediction method suitable for an acid rolling unit, and the method comprises the following steps: S1, predicting the cross angle of a middle roller according to the state of rolling mill equipment; s2, according to the roll shifting working principle of the rolling mill, the inter-roll contact length between the middle roll and the working roll and the inter-roll contact length between the middle roll and the supporting roll after roll shifting are solved; s3, according to the stress condition between the rollers, the roller-to-roller pressure distribution between the middle roller and the working roller and the roller-to-roller pressure distribution between the middle roller and the supporting roller are solved; s4, pre-displacement solving is conducted according to the roller parameters, and a sliding area and a viscous area are divided; and S5, solving an axial force by using a pre-displacement principle. According to the method, the axial force of the middle roller is predicted and calculated through the friction theory according to the analysis of the axial intersection condition of the middle roller, the working roller and the supporting roller.

Description

Technical Field

[0001] The invention relates to cold rolling technology, and more specifically to an axial force prediction method for an intermediate roll of a pickling mill. Background Art

[0002] At present, China's automobile production and sales have accounted for nearly one-third of the global automobile market, becoming the most important market position for domestic and foreign auto companies. In order to meet the demand for automobile plates and users' requirements for lightweight and high-strength performance of the car body. The five-stand six-roller cold rolling mill of the pickling mill is the core equipment for automobile plates. The hot-rolled plate is rolled into a cold hard plate by the rolling mill after pickling. The quality indicators of the product such as thickness, plate shape and plate surface are all guaranteed by the performance of the rolling mill. The inner ring and retaining ring of the intermediate roller bearing on the pickling mill are excessively worn, resulting in bearing failure and causing the unit to shut down. In the on-site production process, while ensuring the performance of the strip, the number of unit shutdowns should be reduced and the unit production efficiency should be improved. After preliminary analysis, the axial force of the intermediate roller of the rolling mill is the direct factor causing bearing damage. The generation of axial force seriously affects the bearing installation accuracy. At the same time, a large parallelism error is generated between the intermediate roller and the arch axis direction.

[0003] During the operation of the unit, problems such as roller diameter wear, bearing seat slide wear, frame window lining surface wear, and installation accuracy affect the parallelism of the intermediate roller, causing the axis of the intermediate roller to intersect with the axis of the working roller and the support roller. Due to the non-parallelism of the axis, there is a crossing angle θ between the axis of the working roller and the axis of the intermediate roller, which makes the surface linear velocity direction of the contact area between the intermediate roller and the working roller inconsistent, causing a "spiral effect" and generating the axial force of the intermediate roller. As for the problem of axial force generation, the axial force can only be controlled but not fundamentally eliminated, which is determined by the characteristics of the rolling mill equipment. When the axial force of the intermediate roller is too large, it will not only cause the bearing to burn out and even cause a fire risk, but also have a great impact on the quality of the rolled product. The axial force of the intermediate roller is predicted, and a timely warning is issued when the axial force is too large, and the rolling mill state is adjusted to further reduce the axial force to avoid accidents.

[0004] At present, the calculation of the axial force of the roll is mainly suitable for the four-roll mill, and the axial force of the working roll is calculated and solved through finite element simulation or friction theory. The influence of the axial force of the intermediate roll of the six-roll mill in the pickling mill on the bearing and the bearing seat is ignored. Therefore, the development of a set of intermediate roll axial force prediction methods suitable for the pickling mill to realize the prediction of the axial force generated by the intermediate roll has become the focus of technical research. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for predicting the axial force of the intermediate roller suitable for the pickling rolling mill. According to the analysis of the axial intersection between the intermediate roller and the working roller and the support roller, the axial force of the intermediate roller is predicted and calculated through the friction theory.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for predicting the axial force of an intermediate roll of a pickling mill, comprising the following steps:

[0008] S1. Predict the cross angle of the intermediate roll according to the equipment status of the rolling mill;

[0009] S2. According to the working principle of roll shifting in the rolling mill, the contact length between the intermediate roll and the working roll, and between the intermediate roll and the backup roll after roll shifting is solved;

[0010] S3. According to the force between the rolls, solve the pressure distribution between the intermediate roll and the working roll, and between the intermediate roll and the support roll;

[0011] S4, solving the pre-displacement according to the roller parameters, and dividing the sliding area and the sticking area;

[0012] S5. Use the pre-displacement principle to solve the axial force.

[0013] Preferably, the step S1 specifically includes:

[0014] Get the maximum clearance S between the bearing seat and the arch on the transmission side of the rolling mill D , unit: mm; the maximum clearance S between the bearing seat and the arch on the working side of the rolling mill W , unit: mm; the axial length L of the arch window, unit: mm;

[0015] Calculate the angle θ between the center line of the intermediate roll and the center line of the mill arch:

[0016] Unit: °.

[0017] Preferably, the step S2 specifically includes the following steps:

[0018] S21. Obtain the roller body length L of the working roller W , unit: mm; the roller length of the intermediate roller is L M , unit: mm; roller body length L of the support roller B , unit: mm;

[0019] Among them, L B =L W , and greater than L M ;

[0020] Roller shifting amount δ, unit: mm;

[0021] Calculate when When the contact length between the working roll and the intermediate roll is L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm;

[0022] in,

[0023] S22, at that time, the contact length between the working roll and the intermediate roll is calculated as L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm;

[0024]

[0025] Preferably, the step S3 specifically includes the following steps:

[0026] S31. Obtain the inlet strip thickness H of the stand, in mm; the outlet strip thickness h of the stand, in mm; the front unit tension σ1 of the stand, in MPa; the rear unit tension σ0 of the stand, in MPa; the radius of the working roll, in mm; the Young's modulus E, in MPa; the Poisson's ratio ν; the plate width B, in mm; the friction coefficient μ between the roll and the strip; the pass average deformation resistance K of the stand m ; Calculate the absolute reduction Δh, unit: mm; Equivalent tension influence coefficient ξ; Elastic flattening radius R' of the working roll, unit: mm; Pass reduction rate r; External friction influence coefficient Q F ; Rolling pressure P, N; calculated as follows:

[0027]

[0028] S32, obtaining the working side bending roll force F of the intermediate roll RW , unit N; driving side bending roll force F of the intermediate roll RD , unit N; calculate the inter-roll pressure F between the working roll and the intermediate roll WM , unit N; the pressure between the support roll and the middle roll F BM , unit N; calculated as follows:

[0029]

[0030] S33, obtain the diameter D of the working roll W , unit: mm; get the diameter D of the middle roller M , unit: mm; get the diameter D of the support roller B , unit mm; calculate the contact pressure q per unit length between the working roll and the intermediate roll wm, unit N; contact pressure per unit length between the support roller and the intermediate roller q bm , unit N; contact area b between working roll and intermediate roll wm , unit: mm; contact area b between support roller and middle roller bm , unit: mm; calculation is as follows:

[0031]

[0032] S34, calculate the unit contact pressure N between the working roll and the intermediate roll WM (X), unit contact pressure between the support roller and the intermediate roller N BM (X); calculated as follows:

[0033]

[0034] Preferably, the step S4 specifically includes the following steps:

[0035] S41, obtain the radius r of the top of a single micro-convex body, in mm; the micro-convex body misalignment correction coefficient C; the roller curve parameters k1 and k2; the roller surface roughness parameter R max ; Friction coefficient f between rollers; Calculation of Ergofer comprehensive elastic coefficient θ when rollers are in contact with each other; Roller elasticity influence coefficient K v and the relative proximity ε of the two rough contacting objects; solve for the pre-displacement [δ] between the rollers:

[0036]

[0037] S42, when the relative displacement of the two roller bodies reaches the maximum tangential deformation of the surface micro-convex body, it begins to enter the sliding state; calculate the decomposition point b1 of the sliding zone and the sticking zone:

[0038]

[0039] Preferably, the step S5 specifically includes:

[0040] Calculate the axial force F1 between the working roll and the intermediate roll, unit N; the axial force F2 between the support roll and the intermediate roll, unit N; add them together to solve the total axial force F of the intermediate roll, unit N; the calculation is as follows:

[0041]

[0042] The present invention provides a method for predicting the axial force of an intermediate roller applicable to a pickling mill group. The method can predict the axial force of the intermediate roller more accurately, realize monitoring of abnormal axial force of the intermediate roller, and ensure the normal state of the rolling mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of a flow chart of an embodiment of a method for predicting the axial force of an intermediate roller according to the present invention;

[0044] Figure 2 Schematic diagram of parameters of step S1 in the method for predicting the axial force of the intermediate roller of the present invention;

[0045] Figure 3 Schematic diagram of the axial force of the intermediate roller in the embodiment of the method for predicting the axial force of the intermediate roller of the present invention;

[0046] Figure 4 It is a schematic diagram of contact between the working roll, the intermediate roll and the support roll in the embodiment of the intermediate roll axial force prediction method of the present invention. DETAILED DESCRIPTION

[0047] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0048] The present invention also provides a method for predicting the axial force of an intermediate roll of a pickling mill, comprising the following steps:

[0049] S1. Predict the cross angle of the intermediate roll according to the equipment status of the rolling mill, including:

[0050] Get the maximum clearance S between the bearing seat and the arch on the transmission side of the rolling mill D , unit: mm; the maximum clearance S between the bearing seat and the arch on the working side of the rolling mill W , unit: mm; the axial length L of the arch window, unit: mm;

[0051] Calculate the angle θ between the center line of the intermediate roll and the center line of the mill arch:

[0052] Unit: °.

[0053] S2. According to the working principle of roll shifting of the rolling mill, the roll contact lengths between the intermediate roll and the working roll, and between the intermediate roll and the backup roll after roll shifting are solved, which specifically includes the following steps:

[0054] S21. Obtain the roller body length L of the working roller W , unit: mm; the roller length L of the intermediate roller M , unit: mm; roller body length L of the support roller B , unit: mm;

[0055] Among them, L B =L W , and greater than L M ;

[0056] Roller shifting amount δ, unit: mm;

[0057] Calculate when When the contact length between the working roll and the intermediate roll is L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm;

[0058] in,

[0059] S22, at that time, the contact length between the working roll and the intermediate roll is calculated as L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm;

[0060]

[0061] S3. According to the force conditions between the rolls, the pressure distribution between the intermediate roll and the working roll, and between the intermediate roll and the support roll is solved, which specifically includes the following steps:

[0062] S31. Obtain the inlet strip thickness H of the stand, in mm; the outlet strip thickness h of the stand, in mm; the front unit tension σ1 of the stand, in MPa; the rear unit tension σ0 of the stand, in MPa; the radius of the working roll, in mm; the Young's modulus E, in MPa; the Poisson's ratio ν; the plate width B, in mm; the friction coefficient μ between the roll and the strip; the pass average deformation resistance K of the stand m ; Calculate the absolute reduction Δh, unit: mm; Equivalent tension influence coefficient ξ; Elastic flattening radius R' of the working roll, unit: mm; Pass reduction rate r; External friction influence coefficient Q F ; Rolling pressure P, N; calculated as follows:

[0063]

[0064] S32, obtaining the working side bending roll force F of the intermediate roll RW , unit N; driving side bending roll force F of the intermediate roll RD , unit N; calculate the inter-roll pressure F between the working roll and the intermediate roll WM , unit N; the pressure between the support roll and the middle roll F BM , unit N; calculated as follows:

[0065]

[0066] S33, obtain the diameter D of the working roll W , unit: mm; get the diameter D of the middle roller M , unit: mm; get the diameter D of the support roller B , unit mm; calculate the contact pressure q per unit length between the working roll and the intermediate roll wm, unit N; contact pressure per unit length between the support roller and the intermediate roller q bm , unit N; contact area b between working roll and intermediate roll wm , unit: mm; contact area b between support roller and middle roller bm , unit: mm; calculation is as follows:

[0067]

[0068] S34, calculate the unit contact pressure N between the working roll and the intermediate roll WM (X), unit contact pressure between the support roller and the intermediate roller N BM (X); calculated as follows:

[0069]

[0070] S4, performing pre-displacement solution according to roller parameters and dividing the sliding area and the sticking area, specifically including the following steps:

[0071] S41, obtain the radius r of the top of a single micro-convex body, in mm; the micro-convex body misalignment correction coefficient C; the roller curve parameters k1 and k2; the roller surface roughness parameter R max ; Friction coefficient f between rollers; Calculation of Ergofer comprehensive elastic coefficient θ when rollers are in contact with each other; Roller elasticity influence coefficient K v and the relative proximity ε of the two rough contacting objects; solve for the pre-displacement [δ] between the rollers:

[0072]

[0073] S42, when the relative displacement of the two roller bodies reaches the maximum tangential deformation of the surface micro-convex body, it begins to enter the sliding state; calculate the decomposition point b1 of the sliding zone and the sticking zone:

[0074]

[0075] S5. Use the pre-displacement principle to solve the axial force, including:

[0076] Calculate the axial force F1 between the working roll and the intermediate roll, unit N; the axial force F2 between the support roll and the intermediate roll, unit N; add them together to solve the total axial force F of the intermediate roll, unit N; the calculation is as follows:

[0077]

[0078] The present invention is applicable to the prediction method of the axial force of the intermediate roller of the acid rolling unit. According to the analysis of the axial crossing of the intermediate roller, the working roller and the supporting roller, the axial force of the intermediate roller is predicted and calculated by the friction theory. First, by analyzing the crossing of the intermediate roller, the crossing angle of the intermediate roller axis is solved; secondly, the contact length and pressure between the intermediate roller and the working roller, and between the intermediate roller and the supporting roller are solved; then, the pre-displacement between the rollers is solved by the friction theory, and the sliding area and the sticking area are divided; finally, the axial force between the intermediate roller and the working roller, and between the intermediate roller and the supporting roller is solved respectively by the pre-displacement principle, and the total axial force of the intermediate roller is obtained by adding and solving.

[0079] Example 1

[0080] Taking the acid rolling mill of a domestic steel plant as an example, the method for predicting the axial force of the intermediate roller of the acid rolling mill applicable to the present invention is described in detail.

[0081] Combination Figure 1 As shown, the method for predicting the axial force of the intermediate roller in this embodiment 1 includes the following steps:

[0082] S1. Obtain the maximum clearance S between the bearing seat 1 and the arch 2 on the transmission side of the six-high rolling mill D 0.65mm; the maximum clearance S between the bearing seat 3 and the arch 4 on the working side (operating side) of the six-high rolling mill W is 0.47 mm; the axial length L of the windows of arches 2 and 4 is 4000 mm; the angle θ between the axis of the intermediate roller 5 and the center line of the windows of arches 2 and 4 is calculated to be 0.016°.

[0083]

[0084] S2. Obtain the roller body length L of the working roller W =1850mm, the roller length of the middle roller L M =1835mm, support roller body length L B =1850mm; roller shifting amount δ = 200mm, such as Figure 4 Calculate the contact length L between the working roll and the intermediate roll WM =1642.5mm; contact length L between support roller and intermediate roller BM =1642.5mm;

[0085]

[0086] S3. According to the force between the rolls, solve the pressure distribution between the intermediate roll and the working roll, and between the intermediate roll and the support roll;

[0087] S31, the strip inlet thickness H of the rack is 2.2mm; the strip outlet thickness h is 1.6mm; the front unit tension σ1 of the rack is 30MPa; the rear unit tension σ0 of the rack is 108MPa; the radius R of the working roll W 450mm; Young's modulus E is 210000MPa; Poisson's ratio ν is 0.3; plate width B is 968mm; friction coefficient μ between roll and strip is 0.05; average deformation resistance K per pass of the stand m is 546MPa; the absolute reduction Δh is 0.6mm; the equivalent tension influence coefficient ξ is 84.6; the elastic flattening radius R' of the working roll is 271mm; the pass reduction rate r is 0.27; the external friction influence coefficient Q F is 1.05; the final calculated rolling pressure P is 6360072N.

[0088]

[0089] S32, obtaining the bending roll force F of the working side of the intermediate roll RW 500000N; the bending force F of the intermediate roller on the transmission side RD is 500000N; calculate the inter-roll pressure F between the working roll and the intermediate roll WM The interroll pressure F between the support roller and the middle roller is 6360072N. BM is 6360072N;

[0090]

[0091] S33, obtain the diameter D of the working roll W 430mm; the diameter of the middle roller D M 510mm; the diameter of the support roller D B is 1300mm; the contact pressure per unit length of the working roll and the intermediate roll q can be calculated wm is 3872N; the contact pressure per unit length between the support roller and the intermediate roller is q bm is 4482N; the contact area b between the working roll and the intermediate roll wm 2.34mm; contact area b between support roller and middle roller bm 3.1mm;

[0092]

[0093] S34. Based on the above acquired data, the unit contact pressure N between the working roll and the intermediate roll is solved. WM (x) Unit contact pressure with the backup roll and the intermediate roll N BM The expression of (x), Unit: mm;

[0094]

[0095] S4, solving the pre-displacement according to the roller parameters, and dividing the sliding area and the sticking area;

[0096] S41, the radius r of the top of a single micro-convex body is 0.008mm; the micro-convex body misalignment correction coefficient C is 0.98; the roller curve parameters k1 and k2 are 0.6 and 2 respectively; the roller surface roughness parameter R max is 0.0094; the friction coefficient between the rollers f is 0.08; the Ergofer comprehensive elastic coefficient θ and the roller elastic influence coefficient K are calculated when the rollers are in contact with each other. v As well as the relative proximity ε of the two rough contact objects, the final solution is that the pre-displacement [δ] between the rollers is 0.0019.

[0097]

[0098] S42, when the relative displacement of the two roller bodies reaches the maximum tangential deformation of the surface micro-convex body, the rollers begin to enter the sliding state. The decomposition point b1 of the sliding zone and the sticking zone is calculated to be 0.12.

[0099]

[0100] S5. Calculate the axial force F1 between the working roll and the intermediate roll, which is 25189N; the axial force F2 between the support roll and the intermediate roll, which is 225696N; add and solve the total axial force F of the intermediate roll, which is 477288N. Figure 3 shown.

[0101]

[0102] Example 2

[0103] Taking the acid rolling mill of a domestic steel plant as an example, the method for predicting the axial force of the intermediate roller of the acid rolling mill applicable to the present invention is described in detail.

[0104] Combination Figure 1 As shown, the method for predicting the axial force of the intermediate roller in this embodiment 2 includes the following steps:

[0105] S1. Obtain the maximum clearance S between the bearing seat 1 and the arch 2 on the transmission side of the six-high rolling mill D 0.52mm; the maximum clearance S between the bearing seat 3 and the arch 4 on the working side (operating side) of the six-high rolling mill W is 0.45 mm; the axial length L of the windows of the arches 2 and 4 is 4000 mm; the angle θ between the axis of the intermediate roller 5 and the center line of the windows of the arches 2 and 4 is calculated to be 0.014°.

[0106]

[0107] S2. Obtain the roller body length L of the working roller W =1850mm, the roller length of the middle roller L M =1835mm, support roller body length L B =1850mm; roller shifting amount δ = 100mm, such as Figure 4 Calculate the contact length L between the working roll and the intermediate roll WM =1642.5mm; contact length L between support roller and intermediate roller BM =1742.5mm;

[0108]

[0109] S3. According to the force between the rolls, solve the pressure distribution between the intermediate roll and the working roll, and between the intermediate roll and the support roll;

[0110] S31, the strip inlet thickness H of the rack is 2mm; the strip outlet thickness h is 1.5mm; the front unit tension σ1 of the rack is 35MPa; the rear unit tension σ0 of the rack is 98MPa; the radius R of the working roll W 450mm; Young's modulus E is 210000MPa; Poisson's ratio ν is 0.3; plate width B is 1200mm; friction coefficient μ between roll and strip is 0.05; average deformation resistance K per pass of the stand m is 546MPa; the absolute reduction Δh is 0.5mm; the equivalent tension influence coefficient ξ is 84.6; the elastic flattening radius R' of the working roll is 271mm; the pass reduction rate r is 0.25; the external friction influence coefficient Q F is 1.05; the final calculated rolling pressure P is 7284232N.

[0111]

[0112] S32, obtaining the bending roll force F of the working side of the intermediate roll RW 300000N; the bending force F of the intermediate roller on the transmission side RD is 300000N; calculate the inter-roll pressure F between the working roll and the intermediate roll WM The pressure between the support roller and the middle roller is 7284232N. BM is 7884232N;

[0113]

[0114] S33, obtain the diameter D of the working roll W 430mm; the diameter of the middle roller D M 510mm; the diameter of the support roller D Bis 1300mm; the contact pressure per unit length of the working roll and the intermediate roll q can be calculated wm is 3872N; the contact pressure per unit length between the support roller and the intermediate roller is q bm is 4482N; the contact area b between the working roll and the intermediate roll wm 2.34mm; contact area b between support roller and middle roller bm 3.1mm;

[0115]

[0116] S34. Based on the above acquired data, the unit contact pressure N between the working roll and the intermediate roll is solved. WM (x) Unit contact pressure with the backup roll and the intermediate roll N BM The expression of (x), Unit: mm;

[0117]

[0118] S4, solving the pre-displacement according to the roller parameters, and dividing the sliding area and the sticking area;

[0119] S41, the radius r of the top of a single micro-convex body is 0.008mm; the micro-convex body misalignment correction coefficient C is 0.98; the roller curve parameters k1 and k2 are 0.6 and 2 respectively; the roller surface roughness parameter R max is 0.0094; the friction coefficient between the rollers f is 0.08; the Ergofer comprehensive elastic coefficient θ and the roller elastic influence coefficient K are calculated when the rollers are in contact with each other. v As well as the relative proximity ε of the two rough contact objects, the final solution is that the pre-displacement [δ] between the rollers is 0.0018.

[0120]

[0121] S42, when the relative displacement of the two roller bodies reaches the maximum tangential deformation of the surface micro-convex body, the rollers begin to enter the sliding state. The decomposition point b1 of the sliding zone and the sticking zone is calculated to be 0.13.

[0122]

[0123] S5. Calculate the axial force F1 between the working roll and the intermediate roll as 262009N; the axial force F2 between the support roll and the intermediate roll as 234885N; add and solve the total axial force F of the intermediate roll as 496895N. Figure 3 shown.

[0124]

[0125] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for predicting the axial force of the intermediate roll of a pickling mill, characterized in that: The following steps are involved: S1. Predict the cross angle of the intermediate roll according to the equipment status of the rolling mill; S2. According to the working principle of roll shifting in the rolling mill, the contact length between the intermediate roll and the working roll, and between the intermediate roll and the backup roll after roll shifting is solved; S3. According to the force between the rolls, solve the pressure distribution between the intermediate roll and the working roll, and between the intermediate roll and the support roll; S4, solving the pre-displacement according to the roller parameters, and dividing the sliding area and the sticking area; S5. Use the pre-displacement principle to solve the axial force.

2. The method for predicting the axial force of the intermediate roll of the pickling mill according to claim 1 is characterized in that: The step S1 specifically includes: Get the maximum clearance S between the bearing seat and the arch on the transmission side of the rolling mill D , unit: mm; the maximum clearance S between the bearing seat and the arch on the working side of the rolling mill W , unit: mm; the axial length L of the arch window, unit: mm; Calculate the angle θ between the center line of the intermediate roll and the center line of the mill arch: Unit: °.

3. The method for predicting the axial force of the intermediate rolls of the pickling mill according to claim 1 is characterized in that: The step S2 specifically includes the following steps: S21. Obtain the roller body length L of the working roller W , unit: mm; the roller length L of the intermediate roller M , unit: mm; roller length L of the support roller B , unit: mm; Among them, L B =L W , and greater than L M ; Roller shifting amount δ, unit: mm; Calculate when When the contact length between the working roll and the intermediate roll is L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm; in, S22, at that time, the contact length between the working roll and the intermediate roll is calculated as L WM , unit: mm; the contact length between the support roller and the middle roller is L BM , unit: mm; 4. The method for predicting the axial force of the intermediate rolls of the pickling mill according to claim 1 is characterized in that: The step S3 specifically comprises the following steps: S31. Obtain the inlet strip thickness H of the stand, in mm; the outlet strip thickness h of the stand, in mm; the front unit tension σ1 of the stand, in MPa; the rear unit tension σ0 of the stand, in MPa; the radius of the working roll, in mm; the Young's modulus E, in MPa; the Poisson's ratio ν; the plate width B, in mm; the friction coefficient μ between the roll and the strip; the pass average deformation resistance K of the stand m ; Calculate the absolute reduction Δh, unit: mm; Equivalent tension influence coefficient ξ; Elastic flattening radius R' of the working roll, unit: mm; Pass reduction rate r; External friction influence coefficient Q F ; Rolling pressure P, N; calculated as follows: S32, obtaining the working side bending roll force F of the intermediate roll RW , unit N; driving side bending roll force F of the intermediate roll RD , unit N; calculate the inter-roll pressure F between the working roll and the intermediate roll WM , unit N; the roller pressure between the support roller and the middle roller F BM , unit N; calculated as follows: S33, obtain the diameter D of the working roll W , unit: mm; get the diameter D of the middle roller M , unit: mm; get the diameter D of the support roller B , unit mm; calculate the contact pressure q per unit length between the working roll and the intermediate roll wm , unit N; contact pressure per unit length between the support roller and the intermediate roller q bm , unit N; contact area b between working roll and intermediate roll wm , unit: mm; contact area b between support roller and middle roller bm , unit: mm; calculation is as follows: S34, calculate the unit contact pressure N between the working roll and the intermediate roll WM (X), unit contact pressure between the support roller and the intermediate roller N BM (X); calculated as follows:

5. The method for predicting the axial force of the intermediate rolls of the pickling mill according to claim 1 is characterized in that: The step S4 specifically comprises the following steps: S41, obtain the radius r of the top of a single micro-convex body, in mm; the micro-convex body misalignment correction coefficient C; the roller curve parameters k1 and k2; the roller surface roughness parameter R max ; Friction coefficient f between rollers; Calculation of Ergofer comprehensive elastic coefficient θ when rollers are in contact with each other; Roller elasticity influence coefficient K v and the relative proximity ε of the two rough contacting objects; solve for the pre-displacement [δ] between the rollers: S42, when the relative displacement of the two roller bodies reaches the maximum tangential deformation of the surface micro-convex body, it begins to enter the sliding state; calculate the decomposition point b1 of the sliding zone and the sticking zone:

6. The method for predicting the axial force of the intermediate rolls of the pickling mill according to claim 1, characterized in that: The step S5 specifically includes: Calculate the axial force F1 between the working roll and the intermediate roll, unit N; the axial force F2 between the support roll and the intermediate roll, unit N; add them together to solve the total axial force F of the intermediate roll, unit N; the calculation is as follows:

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