A method for predicting rolling force during hot-rolled finished strip production

Abstract

The present invention discloses a method for predicting rolling force during the production process of hot-rolled finished plate and strip, and belongs to the field of rolling technology. In order to solve the problems of long rolling force prediction time and low prediction accuracy in the current hot-rolled finished rolling production process, the present invention determines the slab entrance thickness, exit thickness, entrance width and entrance temperature according to the process specification data of a certain pass of hot-rolled finished rolling; detects the roller speed, the slab entrance speed and exit speed, obtains the original radius of the roller and the friction factor between the roller and the slab; predicts the rolling force during the production process of hot-rolled finished plate and strip based on the minimization of the total power functional of the rolling deformation zone; and calculates the rolling force that meets the convergence conditions through iterative calculation based on the mutual coupling of the rolling force and the roller flattening radius. The present invention is safe and reliable, has accurate calculation, and can calculate the rolling force in the continuous rolling process online and in real time, while saving production investment costs and improving the control accuracy of product thickness.

Description

Technical Field

[0001] The invention belongs to the technical field of rolling, and in particular relates to a method for predicting rolling force in a production process of hot-rolled finished plate and strip. Background Art

[0002] Hot-rolled finished sheet and strip boasts excellent properties such as high strength, good toughness, easy formability, and excellent weldability, making it widely used in the manufacturing of ships, automobiles, machinery, bridges, and other industries. With economic development and social progress, the automotive, shipbuilding, and bridge manufacturing industries have rapidly expanded, leading to increasing market demand for hot-rolled finished sheet and strip, and a continuous increase in production. With this increase in production, downstream industries are also increasingly demanding hot-rolled finished sheet and strip, with dimensional accuracy and shape quality becoming key product specifications.

[0003] Rolling force is the most important equipment and process parameter for a rolling mill. The calculation accuracy of the rolling force model directly affects the accuracy of rolling schedule settings, plate thickness accuracy, and plate shape quality. The rolling force model is the foundation of rolling process control. In the increasingly competitive global steel mill environment, driven by the need for cost-effectiveness, flexibility, operational safety, and skilled labor, automatic control systems have become essential tools for large-scale manufacturing. Accurately predicting rolling force and torque is a key challenge in automated control of hot strip finishing mill lines.

[0004] Currently, research on rolling forces primarily relies on engineering methods and the finite element method. The engineering method uses approximate calculations and simplifies the mathematical model, leaving room for improvement in prediction accuracy. The finite element method is the best approach for studying complex deformations, but it is computationally intensive and time-consuming, and each calculation can only display results for a specific process. Therefore, a prediction method with shorter calculation times and higher accuracy is urgently needed in actual hot finishing production. Summary of the Invention

[0005] Aiming at the problem that the current hot rolling and finishing rolling production process has a long rolling force prediction time and low prediction accuracy, the present invention provides a rolling force prediction method in the hot rolling and finishing rolling plate and strip production process.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for predicting rolling force in a hot-rolled finished plate and strip production process comprises the following steps:

[0008] Step 1: Determine the slab inlet thickness 2h0, outlet thickness 2h1, inlet width 2b0 and inlet temperature T according to the hot rolling finishing process data of a certain pass;

[0009] Step 2: Detect roller speed v R, the slab inlet velocity v0 and outlet velocity v1, obtain the original radius R0 of the roller and the friction factor m between the roller and the slab;

[0010] Step 3: Predict the rolling force during the production of hot-rolled finished strips based on the minimization of the total power functional in the rolling deformation zone;

[0011] Step 3.1: Based on the velocity boundary conditions, volume invariance conditions and geometric equations of the strip rolling deformation zone, establish the velocity field and strain velocity field of the rolling deformation zone that meet the motion permission conditions;

[0012] Step 3.2: Use the velocity at the neutral plane of the rolling deformation zone, the neutral angle, and the geometric dimensions of the slab and the rolls to express the flow rate per second U;

[0013] Step 3.3: Calculate the deformation resistance of the hot-rolled finished slab based on the inlet temperature of the hot-rolled finished slab and the actual material and rolling procedure of the on-site rolling;

[0014] Step 3.4: Calculate the internal deformation power, friction power, and shear power of the hot-rolled slab deformation zone based on the velocity field, strain velocity field, and deformation resistance of the slab to obtain the total power functional;

[0015] Step 3.5: According to the total power functional corresponding to different neutral angles, the minimum value of the total power functional is obtained, and then the force arm coefficient χ is calculated. According to the relationship between the total power functional and the rolling force, the rolling force F is calculated. min ;

[0016] Step 4: Based on the coupling between the rolling force and the roller flattening radius, the rolling force that meets the convergence conditions is calculated through iterative calculation.

[0017] Furthermore, in step 3.1, the velocity field and strain velocity field of the rolling deformation zone that meet the motion permission conditions are established based on the velocity boundary conditions, volume invariance conditions and geometric equations of the strip rolling deformation zone, as follows:

[0018] The coordinate system is established with the midpoint of the cross section at the entrance of the slab deformation zone as the origin. x, y, and z represent the length, width, and thickness directions of the slab, respectively. The velocity field in the hot rolling and finishing deformation zone is:

[0019]

[0020]

[0021]

[0022] where v x 、v y 、v zare the velocity components in the length, width and thickness directions of the slab respectively; v0 is the slab inlet velocity, h x half of the slab thickness at any position in the rolling deformation zone; h' x h x The first derivative h' x =dh x / dx, h0 is the inlet half thickness;

[0023]

[0024]

[0025] Among them, R is the roller flattening radius, h1 is the outlet half thickness, l is the projection of the contact arc between the slab and the roller in the rolling direction, R0 is the original radius of the roll, α is the angle between the line connecting any point in the deformation zone and the center of the roll and the line connecting the centers of the rolls;

[0026] The strain velocity field in the hot rolling deformation zone is:

[0027]

[0028]

[0029]

[0030] in are the strain velocity components in the length, width and thickness directions of the slab, respectively.

[0031] Furthermore, in step 3.2, the flow rate per second U is expressed using the velocity at the neutral plane of the rolling deformation zone, the neutral angle, and the geometric dimensions of the slab and the rolls, as follows:

[0032] U=v0h0b0=v R cosα n b x (R+h1-Rcosα n )=v1h1b1

[0033] Among them, v0 is the slab inlet velocity, v1 is the slab outlet velocity, h0 is the inlet half thickness, h1 is the outlet half thickness, v R is the roller speed, α n is the neutral angle, b is half the width of the slab, and the width b is considered to be a constant during the rolling process, that is, b=b0=b1=b x , R is the roller flattening radius.

[0034] Furthermore, the step 3.3 calculates the deformation resistance of the hot-rolled finished slab according to the inlet temperature of the hot-rolled finished slab and the actual material and rolling procedure of the on-site rolling, as follows:

[0035]

[0036] σ s is the deformation resistance of the slab, σ0 is the reference deformation resistance, where a1, a2, a3, a4, a5, and a6 are parameters related to the actual rolled material, and strain strain rate v1 is the slab exit speed, h0 is the inlet half thickness, h1 is the outlet half thickness, l is the projection of the contact arc between the slab and the roller in the rolling direction, Kelvin temperature

[0037] Furthermore, in step 3.4, the internal deformation power, friction power, and shear power of the hot-rolled finished slab deformation zone are calculated based on the velocity field, strain velocity field, and deformation resistance of the slab to obtain the total power functional, which is specifically as follows:

[0038] Total power functional:

[0039] Internal deformation power

[0040] Friction power

[0041]

[0042] Shear power

[0043] where σ s is the deformation resistance of hot-rolled finished slab, U is the flow rate per second, ε=(h0-h1) / h0, m is the friction factor between the roller and the slab, b is half the slab width, k is the yield shear stress, R is the roller flattening radius, v R is the roll speed, θ is the angle between the line connecting the entrance contact point and the roll center and the line connecting the roll centers during rolling, α n is the neutral angle, g b and g f are the parameters of the backslip and frontslip zones, h mb and h mf are the average thickness of the backslip and frontslip zones, is the half thickness of the slab at the neutral angle.

[0044] Furthermore, the step 3.5 calculates the total power functional corresponding to different neutral angles to obtain the minimum value of the total power functional Φ min , then calculate the force arm coefficient χ, and calculate the rolling force F according to the relationship between the total power functional and the rolling force min , as follows:

[0045]

[0046] Where: α n is the neutral angle, Φ is the total power functional, is the internal deformation power of the plastic deformation zone of the cold-rolled slab, is the friction power in the plastic deformation zone of the cold-rolled slab, is the shear power in the plastic deformation zone of the cold-rolled slab;

[0047]

[0048]

[0049]

[0050] Where σ s is the deformation resistance of hot-rolled finished slab, ε=(h0-h1) / h0, h0 is the inlet half thickness, m is the friction factor between the roller and the slab, b is half the slab width, k is the yield shear stress, R is the roller flattening radius, v R is the roll speed, θ is the angle between the line connecting the entrance contact point and the roll center and the line connecting the roll centers during rolling, α n is the neutral angle, g b and g f are the parameters of the backslip and frontslip zones, h mb and h mf are the average thickness of the backslip and frontslip zones, is the half thickness of the slab at the neutral angle,

[0051] Lever coefficient χ:

[0052] in

[0053] Rolling force F min :

[0054] Where R0 is the original radius of the roller, R is the flattening radius of the roller, and Δh = h0-h1.

[0055] Furthermore, in step 4, the rolling force that meets the convergence condition is calculated through iterative calculation based on the mutual coupling between the rolling force and the roller flattening radius, as follows:

[0056] Iterative operation:

[0057] Convergence conditions:

[0058] Among them, R0 is the original radius of the roller, R is the flattening radius of the roller, F min is the rolling force, b is half of the slab width, Δh=h0-h1. i is the roller radius of the i-th iteration, R i-1 is the roller radius of the i-1th iteration.

[0059] Compared with the prior art, the present invention has the following advantages:

[0060] The present invention predicts the rolling force of hot-rolled finish steel strip, resulting in a real-time predicted rolling force that is closer to the actual value on site. By comprehensively considering various process parameters during the rolling process, the rolling force during the hot-rolled finish rolling process is accurately predicted, solving the problem of predicting the real-time rolling force during the hot-rolled finish rolling process under different production conditions. The present invention is safe, reliable, and accurate, enabling online, real-time calculation of the rolling force during continuous rolling, thereby reducing production investment costs while improving the control accuracy of product thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0062] Figure 1 This is a deformation diagram of the workpiece during the hot rolling and finishing rolling process in an embodiment of the present invention.

[0063] Figure 2 This is a schematic diagram of one quarter of the hot rolling and finishing deformation zone in an embodiment of the present invention.

[0064] Figure 3 Flowchart of the method for predicting rolling force of hot-rolled finish-rolled strip steel in an embodiment of the present invention. DETAILED DESCRIPTION

[0065] To help those skilled in the art better understand the technical solutions of the present invention, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The embodiments described herein are only a portion of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0066] The rolling force calculation process of hot-rolled finish-rolled slab is as follows: Figure 3 As shown, the following uses the hot-rolled Q235 steel plate with a width of 0.496m as an example to illustrate the process of calculating the rolling force using the method of the present invention. Table 1 shows the rolling data required for the calculation of each pass.

[0067] Table 1 Rolling force calculation parameters

[0068]

[0069]

[0070] Taking the process parameters of the first pass as an example, the following are the detailed calculation steps:

[0071] Step 1: According to the hot rolling finishing process data for the first pass, the slab's inlet half-thickness h0 = 25.00 mm, outlet half-thickness h1 = 17.58 mm, width 2b = 0.496 m, inlet temperature T = 1040.94 ° C, and slab steel grade Q235 are determined;

[0072] Step 2: Detect roller speed v R =0.94m / s, obtain the roller radius R0 =331.50mm, and the friction factor between the slab and the roller m =0.6;

[0073] Step 3: Use the total power functional minimization in the rolling deformation zone to predict the rolling force during the hot-rolled finished strip production process;

[0074] The three-dimensional schematic diagram of one quarter of the hot rolling finishing deformation zone in this embodiment is as follows Figure 2 As shown, the x-axis, y-axis, and z-axis are the length, width, and thickness directions of the slab respectively, and the coordinate origin is selected at the midpoint of the cross section of the deformation zone at the entrance of the current pass. The original radius of the roller is R0, the flattening radius is R, the slab entrance width is 2b, the entrance thickness is 2h0, and the slab thickness after rolling is 2h1, v R is the roll speed, v0 is the slab entrance speed, α is the angle between the line connecting any point in the deformation zone and the center of the roll and the line connecting the centers of the rolls, θ is the angle between the line connecting the entrance contact point and the center of the roll and the line connecting the centers of the rolls during rolling, x is the horizontal distance from any point in the deformation zone to the origin of the entrance coordinates, and l is the horizontal projection length of the contact arc between the roll and the slab during rolling.

[0075] Step 3.1: Based on the velocity boundary conditions, volume invariance conditions and geometric equations of the strip rolling deformation zone, establish the velocity field and strain velocity field of the rolling deformation zone that meet the motion permission conditions;

[0076] The velocity field in the hot rolling deformation zone is:

[0077]

[0078]

[0079]

[0080] where v x 、v y 、v z are the components in the length, width and thickness directions of the slab, h x h' is half of the thickness of the slab at any position in the rolling deformation zone. x h x The first derivative h' x =dh x / dx, h0 is the entrance half thickness.

[0081]

[0082] The strain velocity field in the hot rolling deformation zone is:

[0083]

[0084]

[0085]

[0086] in are the strain velocity components in the opposite directions of the length, width and thickness of the slab, respectively;

[0087] Step 3.2: Use the velocity at the neutral plane of the rolling deformation zone, the neutral angle, and the geometric dimensions of the slab and the rolls to express the flow rate per second U as follows:

[0088] U=v0h0b=v R cosα n b(R+h1-R cosα n )=v1h1b

[0089] Where v R is the roller speed, α n is the neutral angle.

[0090] Step 3.3: According to the inlet temperature T of the hot-rolled finished slab and the actual rolling material and rolling procedure on site, the deformation resistance of the hot-rolled finished slab is obtained:

[0091]

[0092] Where σ s is the deformation resistance of the slab, strain strain rate Kelvin temperature

[0093] Substituting the first-pass rolling procedure data, we get:

[0094] strain:

[0095] Contact arc length:

[0096] Strain rate:

[0097] E and Substitute the deformation resistance model to obtain the deformation resistance during this rolling pass:

[0098]

[0099] Step 3.4: Calculate the internal deformation power, friction power, and shear power of the hot-rolled finished slab deformation zone based on the velocity field, strain velocity field, and deformation resistance of the slab to obtain the total power functional.

[0100] The total power functional Φ of hot-rolled slab is the sum of internal deformation power, friction power and shear power:

[0101]

[0102] Step 3.5: According to different neutral angles α n The corresponding total power functional, the minimum value of the total power functional Φ min , then calculate the force arm coefficient χ, and calculate the rolling force F according to the relationship between the total power functional and the rolling force min , as follows:

[0103]

[0104] Get α n =0.11

[0105] Lever coefficient χ:

[0106]

[0107] in

[0108] Rolling force F min :

[0109]

[0110] Step 4: According to the coupling between rolling force and roller flattening radius, the rolling force that meets the convergence conditions is calculated through iterative operation. The iterative process is as follows: Figure 3 shown.

[0111] Iterative operation:

[0112]

[0113] Convergence conditions:

[0114]

[0115] The rolling force F is obtained by iteration min =4832.50kN;

[0116] Similarly, the rolling force of each pass in this embodiment can be calculated. The comparison results of the rolling force of each pass are shown in Table 2.

[0117] Table 2 Comparison of rolling force values

[0118]

[0119] In summary, the calculation process of the present invention is complete. Based on field data, the rolling force calculated using the analytical solution of the present invention is compared with the rolling force calculated using the Hill formula and the actual measured rolling force values ​​on site, as shown in the table above. The error between the present invention and the actual measured values ​​is within 9%, indicating that the rolling force prediction of the present invention is closer to the actual measured values ​​on site.

[0120] Any matters not described in detail in this specification are prior art known to those skilled in the art. Although the above description of the present invention is based on specific embodiments to facilitate understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the specific embodiments. As long as various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, such modifications will be obvious to those skilled in the art, and all inventions and creations utilizing the concepts of the present invention are protected.

Claims

1. A method for predicting rolling force during the production of hot-rolled finished strip, characterized by: The following steps are involved: Step 1: Determine the slab inlet thickness according to the hot rolling finishing process data , export thickness , entrance width and inlet temperature ; Step 2: Check the roller speed , slab inlet speed and exit speed , get the original radius of the roller and the friction factor between the roll and the slab ; Step 3: Predict the rolling force during the production of hot-rolled finished strips based on the minimization of the total power functional in the rolling deformation zone; Step 3.1: Based on the velocity boundary conditions, volume invariance conditions and geometric equations of the strip rolling deformation zone, establish the velocity field and strain velocity field of the rolling deformation zone that meet the motion permission conditions; The step 3.1 establishes the velocity field and strain velocity field of the rolling deformation zone that meet the motion permission conditions based on the velocity boundary conditions, volume invariance conditions and geometric equations of the strip rolling deformation zone, as follows: The coordinate system is established with the midpoint of the cross section at the entrance of the slab deformation zone as the origin. x, y, and z represent the length, width, and thickness directions of the slab, respectively. The velocity field in the hot rolling and finishing deformation zone is: ； in, 、 、 are the velocity components in the length, width and thickness directions of the slab, respectively; is the slab inlet velocity, It is half of the thickness of the slab at any position in the rolling deformation zone; for The first derivative of , is the half thickness of the entrance; ； ； in, is the roller flattening radius, is the exit half thickness, l is the projection of the contact arc between the slab and the roller in the rolling direction, , is the original radius of the roller, It is the angle between the line connecting any point in the deformation zone and the center of the roll and the line connecting the centers of the rolls; The strain velocity field in the hot rolling deformation zone is: ； in 、 、 are the strain velocity components in the length, width and thickness directions of the slab, respectively; Step 3.2: Use the velocity at the neutral plane of the rolling deformation zone, the neutral angle, and the geometric dimensions of the slab and the roll to express the flow rate per second ; Step 3.3: Calculate the deformation resistance of the hot-rolled finished slab based on the inlet temperature of the hot-rolled finished slab and the actual material and rolling procedure of the on-site rolling; Step 3.4: Calculate the internal deformation power, friction power, and shear power of the hot-rolled slab deformation zone based on the velocity field, strain velocity field, and deformation resistance of the slab to obtain the total power functional; Step 3.5: Based on the total power functional corresponding to different neutral angles, obtain the minimum value of the total power functional and then calculate the force arm coefficient , , according to the relationship between the total power functional and the rolling force, the rolling force is calculated ; Step 4: Based on the coupling between the rolling force and the roller flattening radius, the rolling force that meets the convergence conditions is calculated through iterative calculation.

2. The method for predicting rolling force during the production of hot-rolled finished strip according to claim 1, characterized in that: The step 3.2 uses the speed at the neutral plane of the rolling deformation zone, the neutral angle and the geometric dimensions of the slab and the roll to express the flow rate per second. , as follows: ； in, is the slab inlet velocity, is the slab outlet speed, is the inlet half thickness, is the outlet half thickness, is the roller speed, is the neutral angle, b is half of the slab width, and the width b is considered to be a constant during the rolling process, that is, , is the roller flattening radius.

3. The method for predicting rolling force in the production process of hot-rolled finished strip according to claim 1, characterized in that: The step 3.3 calculates the deformation resistance of the hot-rolled finished slab according to the inlet temperature of the hot-rolled finished slab and the actual material and rolling procedure of the on-site rolling, as follows: ； is the deformation resistance of hot-rolled finished slab, is the reference deformation resistance, where 、 、 、 、 、 It is a parameter related to the actual rolled material, strain , strain rate , is the slab outlet speed, is the inlet half thickness, is the outlet half thickness, is the projection of the contact arc between the slab and the roller in the rolling direction, , Kelvin temperature .

4. The method for predicting rolling force in the production process of hot-rolled finished plate and strip according to claim 1, characterized in that: The step 3.4 calculates the internal deformation power, friction power and shear power of the hot-rolled finished slab deformation zone based on the velocity field, strain velocity field and deformation resistance of the slab to obtain the total power functional, which is as follows: Total power functional: ; Internal deformation power : ; Friction power : ； Shear power : ; in is the deformation resistance of hot-rolled finished slab, The unit is the flow rate per second, , is the friction factor between the roller and the slab, is half the width of the slab, is the yield shear stress, is the roller flattening radius, is the roller speed, It is the angle between the line connecting the entrance contact point and the center of the roll and the line connecting the centers of the rolls during rolling. is the neutral angle, and are the parameters of the backslip and frontslip zones, , , and are the average thickness of the backslip and frontslip zones, , , is the half thickness of the slab at the neutral angle.

5. The method for predicting rolling force in the production process of hot-rolled finished plate and strip according to claim 1, characterized in that: Step 3.5 calculates the total power functional corresponding to different neutral angles and obtains the minimum value of the total power functional , then calculate the moment arm coefficient , according to the relationship between the total power functional and the rolling force, the rolling force is calculated , as follows: ； in: is the neutral angle, is the total power functional, is the internal deformation power of the plastic deformation zone of the cold-rolled slab, is the friction power in the plastic deformation zone of the cold-rolled slab, is the shear power in the plastic deformation zone of the cold-rolled slab; ； ； ； Where, is the deformation resistance of hot-rolled finished slab, , , is the inlet half thickness, is the outlet half thickness, is the friction factor between the roller and the slab, is half the width of the slab, is the yield shear stress, is the roller flattening radius, is the roller speed, It is the angle between the line connecting the entrance contact point and the center of the roll and the line connecting the centers of the rolls during rolling. is the neutral angle, and are the parameters of the backslip and frontslip zones, , , and are the average thickness of the backslip and frontslip zones, , , is the half thickness of the slab at the neutral angle; Lever coefficient : ; in ; Rolling force : ; in is the original radius of the roller, is the roller flattening radius, .

6. The method for predicting rolling force in the production process of hot-rolled finished plate and strip according to claim 1, characterized in that: In step 4, the rolling force that meets the convergence condition is calculated through iterative calculation based on the coupling between the rolling force and the roller flattening radius, as follows: Iterative operation: ; Convergence conditions: ; in, is the original radius of the roller, is the roller flattening radius, is the rolling force, is half the width of the slab, ; is the roller radius of the i-th iteration, is the roller radius of the i-1th iteration.

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