A parameter optimization method for suppressing mill vibration based on negative damping effect

Abstract

The present invention belongs to the technical field of automatic production in the rolling process, and particularly relates to a parameter optimization method for suppressing mill vibration based on the negative damping effect. This method takes into account the effects of damping, dynamic stiffness, and torsional vibration generated after the change of relevant parameters, and establishes a single-stand flutter model based on vertical-torsional coupling. Considering running wear, power transmission loss, and different upper and lower surface friction coefficients resulting in speed differences between the upper and lower work rolls, a dynamic rolling process model for asynchronous rolling is established. The coupled single-stand flutter model is solved using the Runge-Kutta algorithm, and the vertical vibration displacement of the work roll is used as the basis for judging the stability of the mill. This method can more accurately predict the stability of the mill during the rolling process under the set rolling process parameters. It is of great significance for optimizing the process parameters of cold tandem rolling.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic production in the rolling process, and relates to a parameter optimization method for suppressing mill vibration based on the negative damping effect. Background Art

[0002] The vibration problem of tandem cold rolling mills severely restricts the improvement of product quality and production efficiency. When the mill vibrates, it will seriously affect the thickness accuracy and strip shape quality of the product, cause vibration patterns of light and dark on the strip surface, and affect the coating thickness and coating uniformity during subsequent coating. Establishing a more accurate physical model of mill vibration is not only beneficial to improving and optimizing rolling process parameters, but also conducive to combining the physical model with the data-driven model to promote the application of CPS (Cyber Physical Systems, Cyber-Physical System) in industrial intelligence.

[0003] Regarding the vibration problem in the tandem cold rolling process, researchers have carried out a lot of research work. By preprocessing various data collected during the tandem cold rolling process, selecting appropriate data-driven algorithms to establish a prediction model or an optimal objective function, realizing the prediction of mill vibration, and through the optimization of relevant rolling process parameters, improving the stability of the mill. Many scholars have proved that the vibration of the mill belongs to self-excited vibration, which is caused by the negative damping generated during the rolling process. The existing methods do not start from the physical model of the mill itself and the changes in the roll gap during the rolling process, do not consider the direct impact of the changes in various rolling parameters on the system stability during the vibration process, nor do they consider whether the relevant parameter changes in the deformation zone will generate a negative damping effect and whether it will affect the system stability. In addition, during the tandem cold rolling process, various situations such as threading and biting, dynamic gauge change, acceleration and deceleration, and roll change during stoppage will involve changes in the rolling speed, and operations such as steel biting, steel throwing, and passing through the weld will also involve sudden changes in strip thickness and roll gap. The rolling parameters fluctuate greatly, which is extremely likely to cause torsional vibration of the main drive system and vertical vibration of the mill. Therefore, establishing an accurate model and accurately analyzing the negative damping effect during the rolling process is of great significance for improving the stability of the mill and optimizing the process parameters of tandem cold rolling. Summary of the Invention

[0004] To solve the above technical problems, the purpose of the present invention is to provide a parameter optimization method for suppressing mill vibration based on the negative damping effect, which can more accurately predict the mill stability during the rolling process under the set rolling process parameters. It is of great significance for optimizing the process parameters of tandem cold rolling.

[0005] The present invention provides a parameter optimization method for suppressing mill vibration based on the negative damping effect, including:

[0006] Step 1: Collect the structural parameters of the rolling mill, the structural parameters of the main drive system, the strip parameters during the production process, and the rolling process parameters;

[0007] Step 2: Based on the collected parameters, establish the dynamic model of the vertical structure of the rolling mill, the dynamic model of the torsional structure of the main drive system, and the inter-stand tension model, and perform coupling to obtain the single-stand chatter model;

[0008] Step 3: Calculate the negative damping generated by the dynamic changes of the back tension, front tension, and contact arc length during the unsteady process, and then adjust the damping of the upper and lower work rolls;

[0009] Step 4: Calculate the dynamic stiffness generated by the dynamic change of the friction coefficient using the Roberts friction coefficient formula, and then adjust the stiffness of the upper and lower work rolls;

[0010] Step 5: Establish the dynamic rolling process model of asynchronous rolling, and calculate the dynamic rolling force and dynamic rolling torque during the unsteady process;

[0011] Step 6: Use the Runge-Kutta algorithm to solve the single-stand chatter model, and substitute the obtained vertical vibration displacement and velocity of the work roll, torsional vibration angle and angular velocity into Steps 3 - 6 for the solution of the next cycle;

[0012] Step 7: When the set cycle is reached, judge the stability of the rolling mill according to the vertical vibration displacement curve of the work roll. If the displacement curve converges, it indicates that the rolling mill is stable under the set rolling process parameters; if the displacement curve diverges, the rolling mill vibrates and is in an unstable state.

[0013] A parameter optimization method for suppressing rolling mill vibration based on the negative damping effect of the present invention can calculate the dynamic rolling force, dynamic rolling torque, and the changes in damping and stiffness generated by the changes in rolling process parameters during the unsteady process according to the existing rolling mill structural parameters, main drive system parameters, and rolling process parameters, accurately analyze the influence of negative damping and rolling process parameters on the stability of the rolling mill, and then realize the optimization of rolling parameters, avoid rolling mill vibration, make the cold tandem rolling process run stably and at high speed, and improve the surface quality of the strip. Description of the Drawings

[0014] Figure 1 is a flow chart of a parameter optimization method for suppressing rolling mill vibration based on the negative damping effect of the present invention;

[0015] Figure 2 is the vertical-torsional structure coupling model;

[0016] Figure 3 is a schematic diagram of the force on the micro-element in the asynchronous rolling deformation zone; (a), (b), and (c) are the force diagrams of the micro-elements in the back slip zone, cross-shear zone, and front slip zone respectively;

[0017] Figure 4 It is a curve graph of the work roll displacement response under different process parameters. Figure (a) is the curve graph of the work roll displacement response under different damping; Figure (b) is the curve graph of the work roll displacement response under different back tensions; Figure (c) is the curve graph of the work roll displacement response under different reduction ratios; Figure (d) is the curve graph of the work roll displacement response under different rolling speeds;

[0018] Figure 5 It is the critical rolling speed of the rolling mill under different process parameters. Specific implementation manners

[0019] In order to highlight the advantages of the present invention over other inventions, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0020] As Figure 1 shown, a parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect according to the present invention includes:

[0021] Step 1: Collect the rolling mill structure parameters, the main drive system structure parameters, the strip parameters during the production process, and the rolling process parameters.

[0022] The rolling mill structure parameters include: the mass of the work roll, the mass of the intermediate roll, the mass of the backup roll, the radius of the work roll, the radius of the intermediate roll, the radius of the backup roll, the mass of the housing, and the stiffness and damping of each part of the rolling mill.

[0023] The main drive system structure parameters include: the motor, the reducer, the gearbox, the coupling shaft, the moment of inertia of the work roll, and the stiffness of the motor, the reducer, the gearbox, and the coupling shaft.

[0024] The strip parameters include: the strip grade, the strip width, and the hot-rolled incoming thickness.

[0025] The rolling process parameters include: the strip inlet speed, the strip inlet thickness, the strip outlet thickness, the front tension between stands, the back tension between stands, and the rolling speed of each stand.

[0026] All the required data are obtained from the production site.

[0027] In this embodiment, the rolling mill structure parameters are shown in Table 1, the main drive system structure parameters are shown in Table 2, the strip parameters are shown in Table 3, and the rolling process parameters are shown in Table 4.

[0028] Table 1 Rolling mill structure parameters

[0029]

[0030] Table 2 Main drive structure parameters

[0031]

[0032] Table 3 Strip Steel Parameters

[0033]

[0034] Table 4 Rolling Process Parameters

[0035]

[0036] Step 2: As Figure 2 shown is the vertical-torsional structure coupling model. Based on Figure 2 and according to the collected parameters, establish the dynamic model of the vertical structure of the rolling mill, the dynamic model of the torsional structure of the main drive system, and the inter-stand tension model, and perform coupling to obtain the single-stand chatter model. Specifically:

[0037] Step 2.1: Establish the dynamic model of the vertical structure of the rolling mill. For a six-high cold rolling mill, in order to ensure that the simulation process is as close as possible to the actual rolling process and the result accuracy is higher, study the displacements of each roll and the interactions between the rolls, and establish an eight-degree-of-freedom mass-spring-damper simulation model. According to the dynamic equilibrium differential equations of each structural component, the relationship between the vertical dynamic rolling force change and the displacements of each component is written in matrix form as:

[0038]

[0039] where, ΔP is the dynamic rolling force, , , are the vertical vibration accelerations, velocities, and displacements of each component of the roll respectively, m vi , k vi , c vi are the mass, stiffness, and damping of each component of the roll respectively. When i takes values from 1 to 8, the corresponding components of the roll are the upper housing, upper backup roll, upper intermediate roll, upper work roll, lower work roll, lower intermediate roll, lower backup roll, and lower housing.

[0040] Step 2.2: Establish the dynamic model of the torsional structure of the main drive system, that is, use the lumped parameter method to establish the lumped mass model of the main drive system, and discretize and simplify each component of the rolling mill main drive system. Components with relatively large and concentrated mass, such as the motor rotor, gears, couplings, rolls, etc., are mass-concentrated and simplified into inertial elements without deformation. Components with small mass, dispersed mass distribution, and long dimensions, such as the shaft sections connecting the inertial elements, are simplified into massless elastic elements, and their mass is distributed to the concentrated mass blocks at both ends. It is simplified into a five-degree-of-freedom mass-elastic system, and the relationship between the angular motion of the roll and the change in the torque acting on it is:

[0041]

[0042] Where: ΔM is the dynamic torque; is the torsional vibration angular acceleration of the corresponding components of the main drive system, is the torsional vibration angle of each component of the main drive system; j tj , k tj , are the moment of inertia and rotational stiffness of the corresponding components of the main drive system respectively. When j takes values from 1 to 5, the corresponding components of the main drive system are the motor, reducer, gearbox, coupling shaft and work roll.

[0043] Step 2.3: Establish the inter-stand tension model:

[0044]

[0045] Where, Δσ B is the change in the back tension; Δσ F is the change in the front tension; E is the Young's modulus, with the unit of MPa; L i is the distance between the i-th stand and the (i + 1)-th stand; L i-1 is the distance between the (i - 1)-th stand and the i-th stand; v in,i+1 is the entry speed of the (i + 1)-th stand; v out,i is the exit speed of the i-th stand; v in,i is the entry speed of the i-th stand; v out,i-1 is the exit speed of the (i - 1)-th stand.

[0046] Step 2.4: Couple to obtain the expression of the single-stand flutter model as:

[0047]

[0048] Step 3: Calculate the negative damping effect generated by the dynamic changes of the back tension, front tension and contact arc length during the unsteady process, and then adjust the damping of the upper and lower work rolls, specifically:

[0049] Step 3.1: Calculate the negative damping effect generated by the back tension.

[0050] The back tension fluctuation is:

[0051]

[0052] Where, E is the Young's modulus, v rum is the speed of the upper work roll at steady state, with the unit of m / s 2 ; H m is the entry thickness at steady state, with the unit of mm; R u is the radius of the upper work roll, with the unit of mm; L is the distance between stands, with the unit of m; z, ω are vibration parameters; φu is the angular velocity of torsional vibration of the upper work roll, in rad / s; α u is the bite angle of the upper work roll.

[0053] Therefore, the magnitude of the negative damping effect generated by the back tension can be expressed as:

[0054]

[0055] Step 3.2: Calculate the negative damping effect generated by the front tension.

[0056] Considering the change in angular displacement caused by torsional vibration, the amount of front tension fluctuation generated at the outlet is:

[0057]

[0058] where v rlm is the speed of the upper work roll at steady state, in m / s 2 ; R l is the radius of the lower work roll, in mm; φ l is the angular velocity of torsional vibration of the lower work roll, in rad / s; α l is the bite angle of the lower work roll; h is the strip thickness at the outlet; h l is the thickness at the neutral point of the lower work roll.

[0059] Therefore, the magnitude of the negative damping effect generated by the front tension can be expressed as:

[0060]

[0061] Step 3.3: Calculate the negative damping effect generated by the dynamic change in the contact arc length.

[0062] The change in the contact arc length can be expressed as:

[0063]

[0064] Therefore, the magnitude of the negative damping effect generated by the front tension can be expressed as:

[0065]

[0066] where v out is the outlet speed.

[0067] Step 3.4: The adjusted damping of the upper work roll is:

[0068]

[0069] The adjusted damping of the lower work roll is:

[0070]

[0071] Among them, c v4 is the damping of the upper work roll before adjustment, and c v5 is the damping of the lower work roll before adjustment.

[0072] Step 4: Use the Roberts friction coefficient formula to calculate the dynamic stiffness generated by the dynamic change of the friction coefficient, and then adjust the stiffness of the upper and lower work rolls. Specifically:

[0073] Step 4.1: During the vibration process, the change of the friction coefficient is related to the thickness of the oil film in the deformation zone, and it is approximately calculated by the Roberts friction coefficient formula:

[0074]

[0075] In the formula, f is the friction coefficient during the vibration process; G1 and G2 are constants; R is the radius of the work roll; v r is the rolling speed, and Δh is the reduction; substituting the parameters of the upper and lower work rolls respectively, the friction coefficient f u of the lower work roll and the friction coefficient f l of the upper work roll can be obtained.

[0076] Considering the influence of torsional vibration on the rotational speed of the work roll, the change in rolling force caused by the change in the friction coefficient of the lower work roll is:

[0077]

[0078] The influence of the change in the friction coefficient of the lower work roll on the system stiffness is expressed as:

[0079]

[0080] Among them, is the speed of the lower work roll at steady state, m / s 2 ; R l is the radius of the lower work roll, mm; φ l is the angular velocity of torsional vibration of the lower work roll, rad / s; Z is the vibration parameter; Δh m is the change value of the exit thickness at steady state.

[0081] Similarly, the influence of the change in the friction coefficient of the upper work roll on the system stiffness can be deduced:

[0082]

[0083] Among them, is the speed of the upper work roll at steady state, m / s 2 ; R u is the radius of the upper work roll, mm; φ u is the angular velocity of torsional vibration of the upper work roll, rad / s.

[0084] Step 4.2: The stiffness of the upper work roll after adjustment is:

[0085]

[0086] The stiffness of the lower work roll after adjustment is:

[0087]

[0088] where k v4 is the stiffness of the upper work roll before adjustment, and k v5 is the stiffness of the lower work roll before adjustment.

[0089] Step 5: As shown in the schematic diagram of the forces on the microelement in the asynchronous rolling deformation zone, Figures (a), (b), and (c) are the force diagrams of the microelements in the back slip zone, cross-shear zone, and forward slip zone respectively. Based on Figure 3 this, establish a dynamic rolling process model for asynchronous rolling, and calculate the dynamic rolling force and dynamic rolling torque in the unsteady process, specifically: Figure 3

[0090] Step 5.1: According to the force conditions of the microelement in the asynchronous rolling deformation zone, establish a dynamic rolling process model for asynchronous rolling:

[0091]

[0092] where P is the total rolling pressure, P B is the unit rolling pressure in the back slip zone, P F is the unit rolling pressure in the forward slip zone, P C is the unit rolling pressure in the cross-shear zone; x n1 and x n2 are the positions of the neutral point of the lower work roll and the neutral point of the upper work roll respectively, in mm; l is the length of the deformation zone, in mm.

[0093] In the back slip zone, the equilibrium equations in the horizontal and vertical directions can be obtained.

[0094]

[0095] In the formula, σ x is the stress at position x, in MPa; h x is the strip thickness at position x, in mm; p l , p u are the unit pressures on the lower and upper surfaces of the strip respectively; f l , f u are the friction coefficients between the work roll and the lower and upper surfaces of the strip respectively; α l , α u are... (the text seems incomplete here)They are the bite angles of the lower work roll and the upper work roll respectively.

[0096] The boundary conditions of the back slip zone are and , so the unit rolling pressure p of the back slip zone can be obtained B as:

[0097]

[0098]

[0099]

[0100] In the formula, K is the deformation resistance of the strip in the deformation zone, with the unit of MPa; σ B is the back tension, with the unit of MPa; H is the strip inlet thickness, with the unit of mm.

[0101] In the forward slip zone, the equilibrium equations in the horizontal and vertical directions can be obtained.

[0102]

[0103] The boundary conditions of the forward slip zone are and , so the unit rolling pressure p of the forward slip zone can be obtained F as:

[0104]

[0105]

[0106]

[0107] In the formula, σ F is the forward tension, with the unit of MPa; h is the strip outlet thickness, with the unit of mm.

[0108] In the cross-shear zone, the static mechanical equation can be expressed as:

[0109]

[0110] The boundary conditions on the side of the cross-shear zone close to the back slip zone are and , and the boundary conditions on the side close to the forward slip zone are and , which can be solved according to the principle of volume constancy. And substituting into the equilibrium differential equation of the cross-shear zone, the unit rolling pressure p of the cross-shear zone can be obtained C as:

[0111]

[0112]

[0113]

[0114] Where: h1 is the thickness at the neutral point of the lower work roll, h2 is the thickness at the neutral point of the upper work roll, with the unit of mm. The total rolling pressure can be obtained by integrating the unit rolling pressure along the contact arc length of the deformation zone. The position of the neutral point can be obtained based on the principle of constant volume and h1, h2.

[0115] Step 5.2: Calculate the dynamic rolling force ΔP in the unsteady process according to the following formula:

[0116]

[0117] where ΔH is the change in the entrance thickness, Δh is the change in the exit thickness, and is solved according to the change value y4 - y5 of the roll gap caused by vibration and the change speed ; y4 is the vertical vibration displacement of the upper work roll, y5 is the vertical vibration displacement of the lower work roll; is the vertical vibration speed of the upper work roll, is the vertical vibration speed of the lower work roll.

[0118] Step 5.3: Calculate the dynamic rolling torque ΔM in the unsteady process according to the following formula:

[0119]

[0120] where K vt1 represents the coupling stiffness generated by the interaction between the vertical structure and the torsional structure.

[0121]

[0122] where is the stiffness of the adjusted upper work roll, is the stiffness of the adjusted lower work roll, k t4 is the rotational stiffness of the coupling shaft.

[0123] Step 6: Use the Runge - Kutta algorithm to solve the single - stand flutter model, and substitute the obtained vertical vibration displacement and speed of the work roll, torsional vibration angle and angular velocity into Steps 3 - 6 for the solution of the next cycle;

[0124] Step 7: When the set cycle is reached, judge the stability of the rolling mill according to the vertical vibration displacement curve of the work roll. If the displacement curve converges, it indicates that the rolling mill is stable under the set rolling process parameters; if the displacement curve diverges, the rolling mill vibrates and is in an unstable state.

[0125] The stability analysis of the rolling mill under different process parameters is as follows Figure 4 as shown. In Figure (a), when the system damping is positive, i.e., c>0, the displacement of the work roll is in a convergent state; when the system damping is negative, i.e., c<0, it causes the displacement of the work roll to be in a divergent state, the rolling mill is unstable, and self-excited vibration will occur. In Figure (b), the increase in the back tension makes the displacement curve of the work roll change from divergent to convergent, and the stability of the system is improved, but too much back tension is changed. In Figure (c), the increase in the reduction rate causes the displacement curve of the work roll to change from convergent to divergent, and the stability of the rolling mill decreases. In Figure (d), the increase in the rolling speed also causes the displacement curve of the work roll to change from convergent to divergent, indicating that the higher the rolling speed, the more unstable the rolling mill becomes.

[0126] According to the convergence and divergence degree of the curve of the vertical vibration displacement of the work roll, Figure 5 the variation law of the critical rolling speed under different reduction rates and friction coefficients is given. The larger the critical rolling speed, the higher the stability of the rolling mill. When the rolling process parameters are below the plane shown in Figure 5 the rolling mill is in a stable state. Therefore, according to the variation law of the critical rolling speed, the optimal combination of reduction rate and friction coefficient can be found to optimize the rolling parameters. At the same time, the method of the present invention can judge whether the formulated rolling schedule is reasonable through simulation calculation before production, so as to reduce the test cost, and can also avoid problems such as production accidents and equipment damage.

[0127] The above are only the preferred embodiments of the present invention and are not intended to limit the idea of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect, characterized in that, Including: Step 1: Collect the structural parameters of the rolling mill, the structural parameters of the main drive system, the strip parameters during the production process, and the rolling process parameters; Step 2: According to the collected parameters, establish the dynamic model of the vertical structure of the rolling mill, the dynamic model of the torsional structure of the main drive system, and the inter-stand tension model, and perform coupling to obtain the single-stand chatter model; Step 3: Calculate the negative damping effect generated by the dynamic changes of the back tension, front tension, and contact arc length during the unsteady process, and then adjust the damping of the upper and lower work rolls; Step 4: Calculate the dynamic stiffness generated by the dynamic change of the friction coefficient using the Roberts friction coefficient formula, and then adjust the stiffness of the upper and lower work rolls; Step 5: Establish the dynamic rolling process model of asynchronous rolling, and calculate the dynamic rolling force and dynamic rolling torque during the unsteady process; Step 6: Adopt the Runge-Kutta algorithm to solve the single-stand chatter model, and substitute the obtained vertical vibration displacement and velocity of the work roll, and the torsional vibration angle and angular velocity into Steps 3 - 6 for the solution of the next cycle; Step 7: When the set cycle is reached, judge the stability of the rolling mill according to the vertical vibration displacement curve of the work roll. If the displacement curve converges, it indicates that the rolling mill is stable under the set rolling process parameters; if the displacement curve diverges, the rolling mill vibrates and is in an unstable state.

2. The parameter optimization method for suppressing rolling mill vibration based on negative damping effect according to Claim 1, characterized in that: The structural parameters of the rolling mill include: the mass of the work roll, the mass of the intermediate roll, the mass of the backup roll, the radius of the work roll, the radius of the intermediate roll, the radius of the backup roll, the mass of the stand, the stiffness and damping of each part of the rolling mill; The structural parameters of the main drive system include: the moment of inertia of the motor, reducer, gearbox, coupling shaft, and work roll, and the stiffness of the motor, reducer, gearbox, and coupling shaft; The strip parameters include: the strip grade, strip width, and hot-rolled incoming thickness; The rolling process parameters include: the strip inlet speed, strip inlet thickness, strip outlet thickness, front tension between stands, back tension between stands, and rolling speed of each stand.

3. The parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect according to claim 1, characterized in that, The specific content of Step 2 is as follows: Step 2.1: Establish the dynamic model of the vertical structure of the rolling mill, that is, an eight-degree-of-freedom mass-spring-damping simulation model. According to the dynamic equilibrium differential equations of each structural component, the relationship between the vertical dynamic rolling force change and the displacements of each component is written in matrix form as: where ΔP is the dynamic rolling force, y i are the vertical vibration acceleration, velocity and displacement of each component of the roll, respectively, in m vi , k vi , c vi are the mass, stiffness and damping of each component of the roll, respectively. When i ranges from 1 to 8, the corresponding components of the roll are the upper housing, upper backup roll, upper intermediate roll, upper work roll, lower work roll, lower intermediate roll, lower backup roll and lower housing; Step 2.2: Establish the dynamic model of the torsional structure of the main drive system, that is, use the lumped parameter method to establish the lumped mass model of the main drive system. Discretize and simplify each component of the rolling mill main drive system into a five-degree-of-freedom mass-elastic system. The relationship between the angular motion of the roll and the change of the torque acting on it is: Where: ΔM is the dynamic torque; is the torsional vibration angular acceleration of the corresponding components of the main drive system, and θ j is the torsional vibration angle of each component of the main drive system; j tj , k tj are the moment of inertia and rotational stiffness of the corresponding components of the main drive system respectively. When j takes values from 1 to 5, the corresponding components of the main drive system are the motor, reducer, gearbox, coupling shaft and work roll; Step 2.3: Establish the inter-stand tension model: where, Δσ B is the change in back tension; Δσ F is the change in front tension; E is Young's modulus, with the unit of MPa; L i is the distance between the i-th stand and the (i + 1)-th stand; L i-1 is the distance between the (i - 1)-th stand and the i-th stand; v in,i+1 is the inlet speed of the (i + 1)-th stand; v out,i is the outlet speed of the i-th stand; v in,i is the inlet speed of the i-th stand; v out,i-1 is the outlet speed of the (i - 1)-th stand.

4. The parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect according to claim 1, characterized in that, The specific content of Step 3 is as follows: Step 3.1: The magnitude of the negative damping effect generated by the back tension is: Among them, P is the total rolling pressure, σ B is the back tension, E is the Young's modulus, v rum is the speed of the upper work roll at steady state, m / s 2 ; H m is the entrance thickness at steady state, mm; R u is the radius of the upper work roll, mm; L is the distance between stands, m; ω is the vibration parameter; is the angular velocity of torsional vibration of the upper work roll, rad / s; α u is the bite angle of the upper work roll; Step 3.2: The magnitude of the negative damping effect generated by the front tension is: where, σ F is the front tension, v rlm is the speed of the lower work roll at steady state, m / s 2 ; R l is the radius of the lower work roll, mm; is the angular velocity of torsional vibration of the lower work roll, rad / s; α l is the biting angle of the lower work roll; h is the strip thickness at the outlet; h l is the thickness at the neutral point of the lower work roll; Step 3.3: The magnitude of the negative damping effect generated by the dynamic change of the contact arc length is: Among them, v out is the outlet velocity; The adjusted damping of the upper work roll is: The adjusted damping of the lower work roll is: Among them, c v4 is the upper work roll damping before adjustment, and c v5 is the lower work roll damping before adjustment.

5. The parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect according to claim 1, characterized in that, The specific content of Step 4 is as follows: Step 4.1: During the vibration process, the change in the friction coefficient is related to the thickness of the oil film in the deformation zone, and it is approximately calculated using the Roberts friction coefficient formula: where f is the friction coefficient during the vibration process; G1 and G2 are constants; R is the radius of the work roll; v r is the rolling speed, and Δh is the reduction; substituting the parameters of the upper and lower work rolls respectively gives the friction coefficient f u of the lower work roll and the friction coefficient f l ; Considering the influence of torsional vibration on the working roll speed, the change in the rolling force caused by the change in the friction coefficient of the lower working roll is: The influence of the change in the friction coefficient of the lower working roll on the system stiffness is expressed as: Among them, v rlm is the speed of the lower work roll at steady state, m / s 2 ; R l is the radius of the lower work roll, mm; is the angular velocity of torsional vibration of the lower work roll, rad / s; Z is the vibration parameter; Δh m is the change value of the exit thickness at steady state; Similarly, the influence of the change in the friction coefficient of the upper working roll on the system stiffness is deduced: where v rum is the speed of the upper work roll at steady state, m / s 2 ; R u is the radius of the upper work roll, mm; is the angular velocity of torsional vibration of the upper work roll, rad / s; Step 4.2: The adjusted stiffness of the upper working roll is: The adjusted stiffness of the lower working roll is: where k v4 is the stiffness of the upper work roll before adjustment, and k v5 is the stiffness of the lower work roll before adjustment.

6. The parameter optimization method for suppressing the vibration of a rolling mill based on the negative damping effect according to claim 1, wherein The specific content of the said Step 5 is: Step 5.1: According to the force condition of the micro-element in the asynchronous rolling deformation zone, establish a dynamic rolling process model for asynchronous rolling: Among them, P is the total rolling pressure, P B is the unit rolling pressure in the back slip zone, P F is the unit rolling pressure in the forward slip zone, P C is the unit rolling pressure in the cross-shearing zone; x n1 and x n2 are the positions at the neutral points of the lower work roll and the upper work roll respectively, with the unit of mm; l is the length of the deformation zone, with the unit of mm; where K is the deformation resistance of the strip in the deformation zone, with the unit of MPa; σ B is the back tension, with the unit of MPa; H is the strip inlet thickness, with the unit of mm; h x is the strip thickness at position x, with the unit of mm; f l and f u are the friction coefficients between the work roll and the lower surface and the upper surface of the strip respectively; α l and α u are the bite angles of the lower work roll and the upper work roll respectively; where σ F is the front tension, in MPa; h is the strip thickness at the outlet, in mm; In the formula: h1 is the thickness at the neutral point of the lower working roll, with the unit of mm; Step 5.2: Calculate the dynamic rolling force ΔP in the non-steady state process according to the following formula: Among them, ΔH is the change in the inlet thickness, and Δh is the change in the outlet thickness. It is solved according to the roll gap change value y4 - y5 caused by vibration and the change speed ; y4 is the vertical vibration displacement of the upper work roll, and y5 is the vertical vibration displacement of the lower work roll; is the vertical vibration speed of the upper work roll, is the vertical vibration speed of the lower work roll; Step 5.3: Calculate the dynamic rolling torque ΔM in the non-steady state process according to the following formula: ΔM = K vt1 y4 Among them, K vt1 represents the coupling stiffness generated by the interaction between the vertical structure and the torsional structure.

7. The parameter optimization method for suppressing mill vibration based on the negative damping effect according to claim 6, characterized in that: Among them, k' v4 is the stiffness of the adjusted upper work roll, k' v5 is the stiffness of the adjusted lower work roll, and k t4 is the rotational stiffness of the coupling shaft.

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