A method and system for determining the shape of pinch rolls

Abstract

The present invention relates to a method and a system for determining the roll shape of pinch rolls. In the method, first, the contact width and length between the pinch rolls and the strip steel are obtained; then, the contact area between the pinch rolls and the strip steel is obtained based on the width and length; then, the frictional force of the pinch rolls is obtained based on the contact area; finally, the tension of the strip steel is obtained based on the frictional force, and the roll shape of the pinch rolls is obtained based on the tension. The roll shape of the pinch rolls determined by the method of the present invention can ensure a high transmission efficiency of the strip steel during the process of passing through the pinch rolls. At the same time, a reasonable roll shape curve of the roll is beneficial to maintaining uniform stress on each part of the roll and avoiding excessive local wear.

Description

Technical Field

[0001] The present invention belongs to the technical field of strip rolling, and particularly relates to a method and system for determining the roll profile of pinch rolls. Background Art

[0002] Before the final stage of hot-rolled strip rolling and before feeding into the coiler, it needs to pass through pinch rolls. The pinch rolls have two functions: to keep the strip shape flat after rolling in the finishing rolling process. It needs to be pre-bent to facilitate feeding into the coiler for coiling. On the other hand, it is necessary to provide a certain tension to the strip after finishing rolling to keep the strip in a compressed state.

[0003] However, during the process of the strip passing through the pinch rolls, in order to provide a certain tension to ensure that the strip can enter the coiler in a compressed state, it is often necessary to increase the pressure between the pinch rolls and the strip. Since the pinch rolls are mostly flat rolls and the strip has a convexity in the middle, the middle wears more than the edges, and the wear of the pinch roll surface is uneven. When rolling thin materials at the end of the pinch roll, due to the small roll gap and large middle wear, sometimes there is no longer a pressing effect on the strip, resulting in serious tail deviation and increased wear of the pinch rolls; at the same time, under the long-term contact between the pinch rolls and the strip, the roll profile of the pinch rolls changes, causing the convexity of the strip to change and affecting the flatness of the strip shape of the strip.

[0004] Frequent replacement of pinch rolls reduces the service life and mid-term stable working period of pinch rolls, limits the increase in the output of thin gauges in the hot rolling process, and is not conducive to giving full play to the production capacity of the production line. Currently, the pinch roll profile models include setting a certain convexity for the upper and lower rolls and increasing the edge chamfer; setting a sixth-degree curve in the middle part of the roll body of the pinch roll and using a quadratic trinomial modification curve and other methods to set the pinch roll profile. However, in order to obtain a suitable roll gap model according to the actual on-site production situation, the number of tests is large and the consumption is high, and there is a lack of theoretical methods for research. Summary of the Invention

[0005] In order to overcome the above problems existing in the prior art, the present invention provides a method and system for determining the roll profile of pinch rolls to solve the above problems existing in the prior art.

[0006] A method for determining the roll profile of a pinch roll includes:

[0007] S1. Obtain the contact width and length between the pinch roll and the strip;

[0008] S2. Obtain the contact area between the pinch roll and the strip according to the width and length;

[0009] S3. Obtain the frictional force of the pinch roll according to the contact area;

[0010] S4. Obtain the tension of the strip according to the frictional force, and determine the roll profile of the pinch roll according to the tension.

[0011] For the aspects and any possible implementation described above, a further implementation is provided. The contact width in S1 is obtained by using a sextic curve to establish a finite element model. The contact length between the upper pinch roll and the strip steel is: L 上 = [arccos(H 1 / R) - β]R;

[0012] The contact length between the lower pinch roll and the strip steel is: L 下 = [arccos(H 2 / r) + β]r.

[0013] Where H 1 is the distance value from the center of the upper pinch roll to the upper surface of the strip steel, H 2 is the distance value from the center of the lower pinch roll to the lower surface of the strip steel, R is the radius of the upper pinch roll, r is the radius of the lower pinch roll, and β is the angle between the lower pinch roll and the coiler in the relative horizontal direction.

[0014] For the aspects and any possible implementation described above, a further implementation is provided. In S2: The contact area between the upper pinch roll and the strip steel is L 上 L 1 ;

[0015] The contact area between the lower pinch roll and the strip steel is L 下 L 2 ,

[0016] Where L 1 and L 2 are the contact widths between the upper pinch roll and the lower pinch roll and the strip steel respectively.

[0017] For the aspects and any possible implementation described above, a further implementation is provided. The frictional force of the upper pinch roll in S3 is:

[0018] F 1 = L 上 L 1 τ b

[0019] The frictional force of the lower pinch roll is: F 2 = L 下 L 2 τ b

[0020] Where τ b is the shear strength.

[0021] For the aspects and any possible implementation described above, a further implementation is provided, where the tension in S4 is the difference between the sum of the frictional forces of the upper and lower rolls of the pinch roll and the resistance.

[0022] For the aspects and any possible implementation described above, a further implementation is provided. Different tension values are obtained according to steps S1 - S4, and the corresponding pinch roll profile is determined according to the relationship between the tension value and the pinch roll profile.

[0023] For the aspects and any possible implementation described above, a further implementation is provided, where the maximum value of the tension is (N 1 +N 2 )μ-N 1 / R(f+μ 1 d 1 / 2)-N 2 / r(f+μ 1 d 2 / 2), where N 1 and N 2 are the clamping forces of the upper and lower rolls of the pinch roll on the strip steel respectively; μ is the sliding friction coefficient between the strip steel and the pinch roll; μ 1 is the friction coefficient at the bearings of the upper and lower rolls of the pinch roll; f is the rolling friction coefficient between the strip steel and the pinch roll, R is the radius of the upper roll of the pinch roll, r is the radius of the lower roll of the pinch roll, d 1 and d 2 are the diameters at the bearings of the upper and lower rolls of the pinch roll respectively.

[0024] For the aspects and any possible implementation described above, a further implementation is provided, where the maximum value of the tension satisfies that the strip steel does not slip when moving in the pinch roll.

[0025] The present invention also provides a system for determining the profile of a pinch roll, including: a processor and a memory for storing executable instructions, where the processor is configured to execute the executable instructions to perform the method for determining the profile of the pinch roll according to the present invention.

[0026] The present invention also provides a computer storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the method for determining the profile of the pinch roll according to the present invention.

[0027] Advantages of the present invention

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method for determining the shape of the pinch roll of the present invention first obtains the contact width and length between the pinch roll and the strip steel; then, obtains the contact area between the pinch roll and the strip steel according to the width and length; then, obtains the frictional force of the pinch roll according to the contact area; finally, obtains the tension of the strip steel according to the frictional force, and obtains the shape of the pinch roll according to the tension. The shape of the pinch roll determined by the method of the present invention can ensure that the strip steel maintains a high transmission efficiency during the process of passing through the pinch roll. At the same time, determining a reasonable roll shape according to the tension is beneficial to maintaining uniform stress on each part of the roll and avoiding excessive local wear. On the premise of taking into account the pinch efficiency and uniform wear, it can effectively improve the service life of the strip steel, reduce local wear, and ensure a certain transmission efficiency, providing higher production efficiency for the production and manufacturing of the strip steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the strip steel running in the pinch roll in the embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the determined pinch roll structure in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the following specific embodiments. Similar technologies and methods should be regarded as within the scope of protection of the present invention. To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0033] It should be clear that the embodiments described in the present invention are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0034] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0035] The method for determining the shape of the pinch roll of the present invention includes the following steps:

[0036] S1. Obtain the contact width and length between the pinch roll and the strip steel;

[0037] S2. Obtain the contact area between the pinch roll and the strip steel according to the width and length;

[0038] S3. Obtain the frictional force of the pinch roll according to the contact area;

[0039] S4. Obtain the tension of the strip steel according to the frictional force, and determine the roll profile of the pinch roll according to the tension.

[0040] Preferably, in the embodiment of the present invention, the contact width of the pinch roll in S1 is obtained by using a sixth-order curve to establish a finite element model of the pinch roll. After respectively establishing the finite element models of the upper roll, lower roll of the pinch roll and the strip steel, the whole process of the strip steel passing through the pinch roll is simulated through the finite element model. During this process, the contact width value when the strip steel passes through the pinch roll can be obtained, such as Figure 2 the L shown 1 , L 2 , where L 1 and L 2 are the widths of the upper roll and the lower roll of the pinch roll respectively. The contact length of the upper roll of the pinch roll is: L 上 =[arccos(H 1 / R)-β]R;

[0041] The contact length of the lower roll of the pinch roll is: L 下 =[arccos(H 2 / r)+β]r.

[0042] Among them, H 1 is the distance value from the center of the upper roll of the pinch roll to the upper plate surface of the strip steel, H 2 is the distance value from the center of the lower roll of the pinch roll to the lower plate surface of the strip steel, R is the radius of the upper roll of the pinch roll, r is the radius of the lower roll of the pinch roll, and β is the angle between the lower roll of the pinch roll and the coiler in the relative horizontal direction.

[0043] Preferably, in the embodiment of the present invention, in S2: the contact area between the upper roll of the pinch roll and the strip steel is L 上 L 1 ;

[0044] The contact area between the lower roll of the pinch roll and the strip steel is L 下 L 2 .

[0045] Preferably, in the embodiment of the present invention, in S3: the frictional force of the upper roll of the pinch roll is: F 1 =L 上 L 1 τ b ;

[0046] The frictional force of the lower roll of the pinch roll is: F 2 =L 下 L 2 Lτ b , where τ b is the shear strength.

[0047] Preferably, in the embodiment of the present invention, the tension in S4 is the difference between the sum of the friction forces of the upper roller and the lower roller of the pinch roller and the resistance.

[0048] Preferably, in an embodiment of the present invention, different tension values ​​are obtained according to steps S1 to S4, and the corresponding roller shape of the pinch roller is determined according to the relationship between the tension value and the roller shape of the pinch roller.

[0049] Preferably, the maximum value of the tension in the embodiment of the present invention is (N 1 +N 2 )μ-N 1 / R(f+μ 1 d 1 / 2)-N 2 / r(f+μ 1 d 2 / 2), where N 1 、N 2 are the clamping forces of the upper and lower pinch rollers on the strip; μ is the sliding friction coefficient between the strip and the pinch rollers; μ 1 is the friction coefficient at the bearings of the upper and lower rollers of the pinch roller; f is the rolling friction coefficient between the strip and the pinch roller, R is the radius of the upper roller of the pinch roller, r is the radius of the lower roller of the pinch roller, d 1 d 2 They are the diameters of the upper and lower roller bearings of the pinch roller respectively.

[0050] Preferably, in the embodiment of the present invention, the minimum value of the tension is such that the strip does not slip when moving in the pinch rollers.

[0051] The specific steps are as follows:

[0052] First, it is assumed that the roller shape of the pinch roller is a sextic curve model, so a finite element model simulation is established to simulate the scene of the strip passing through the pinch roller. Through actual analysis, the contact width value L between the pinch roller and the strip is directly obtained. 1、 L 2 ,like Figure 2 shown.

[0053] The following is a detailed description of the calculation method for obtaining the length value of the strip in contact with the pinch roller. The pinch roller shape calculation model is established using the characteristics of the pinching process, mainly the calculation model of the pinch roller contact area, and the relationship between the friction force and the contact area is obtained using the adhesion friction theory, and the actual tension size under a certain contact area is obtained:

[0054] When the strip is conveyed on the pinch roller, obtain the vertical distance H from the center of the pinch roller to the upper surface of the strip. 1 , the vertical distance H from the center of the lower roller of the pinch roller to the lower surface of the strip 2Let the strip tension be T and the clamping force of the pinch roll on the strip be N. 1 and N 2 The reaction force of the strip on the pinch roll is P 1 and P 2 They are equal in magnitude and opposite in direction. The resistance of the finishing mill is F H .

[0055] As Figure 1 shown, α is the angle between the entry point and the exit point of the upper surface of the strip in the pinch roll, β is the angle between the lower roll of the pinch roll and the horizontal direction relative to the coiler, and γ is the angle between the entry point of the lower surface of the strip in the pinch roll and the vertical direction. In the figure, points A, B, and C are the centers of the upper roll, the lower roll of the pinch roll, and the coiler respectively; D, F, G, and H are the entry point, the exit point of the upper surface of the strip, and the entry point, the exit point of the lower surface of the strip respectively; E and I are the intersection of the perpendicular line from point A and the horizontal line of point F, and the intersection of the perpendicular line from point B and the horizontal line of point C. It is easy to know that cos(α + β) = H 1 / R, cosγ = H 2 / r, and ∠α and ∠(γ + β) are obtained. Calculations are carried out for the DF section and the GH section respectively.

[0056] The contact area between the upper roll and the strip is approximately L 上 L 1 The contact area between the lower roll and the strip is approximately L 下 L 2 .

[0057] In the theory of adhesive friction, the relationship between the contact area, tension, and friction force is

[0058] F = T + F p = Aτ b + F p

[0059] In the formula, F is the friction force, A is the contact area, T is the tension, which refers to the contact area between the upper roll or the lower roll and the strip in this embodiment, and τ b is the shear strength of the adhesive node, that is, two very close asperities form an adhesive node through atomic attraction. Because the pressure is extremely high when the strip passes through the roll and the instantaneous high temperature state is achieved during the friction process, it can be approximately considered that all points are adhesive nodes in this embodiment; Aτ b is the resistance generated by the adhesive effect; F p is the plowing force, which can be approximately ignored. Plowing refers to the phenomenon that the rough peaks of hard materials are embedded in soft materials and then push and squeeze the soft materials during sliding, causing plastic flow and plowing out a groove. In this embodiment, it is mainly sliding friction and almost no groove is generated by plowing, so it can be approximately ignored.

[0060] The friction force of the upper roll is: F1 = L 上 L 1 τ b

[0061] The frictional force of the lower roll is: F 2 = L 下 L 2 τ b

[0062] Analyze the forces acting on the strip steel. During the process of passing through the pinch rolls, the forces it receives include the sliding friction force given by the pinch rolls, the sliding friction force of the finishing rolls, and the rolling friction force of the conveyor belt. The rolling friction force is relatively small and can be ignored. Therefore, the final tension received by the strip steel is:

[0063] T = F 1 + F 2 − F H = L 上 L 1 τ b + L 下 L 2 τ b − F H

[0064] In the formula, F H represents the sliding friction force of the finishing rolls, which is obtained by measuring the parameters of the finishing process. The finally obtained tension value satisfies a certain range, and based on this, a reasonable pinch roll profile design is obtained. By repeating the steps of the present invention, inputting the parameter values of different six-degree curve roll profiles, and comparing whether the actual tension magnitude in multiple repeated experiments conforms to a certain range according to the finite element simulation of different pinch roll profiles, the pinch roll profile within the appropriate range is finally determined. The tension should satisfy being greater than the minimum requirement T 0 of the steel mill, and the strip steel does not slip during movement. Analyze the forces acting on the rolls. The rolls are subject to the sliding friction force between the strip steel and the rolls and the rolling friction force between the bearings and the rolls during operation.

[0065] The sliding friction force between the strip steel and the rolls is (N 1 + N 2 )μ, which has the effect of a thrust force.

[0066] The rolling friction force between the bearings and the rolls is calculated using the pressure and the rolling friction coefficient, and its value is N 1 / R(f + μ 1 d 1 / 2) + N 2 / r(f + μ 1 d 2 / 2), which has the effect of a resistance force.

[0067] It is determined based on the above comprehensive tension range. Therefore, the conditions satisfied by the tension T are as follows:

[0068] T 0 □T□(N 1 +N 2 )μ-N 1 / R(f+μ 1 d 1 / 2)-N 2 / r(f+μ 1 d 2 / 2), where N 1 、N 2 are the clamping forces of the upper and lower rolls of the pinch roll on the strip respectively; μ is the sliding friction coefficient between the strip and the pinch roll; μ 1 is the friction coefficient at the bearings of the upper and lower rolls of the pinch roll; f is the rolling friction coefficient between the strip and the pinch roll, R is the radius of the upper roll of the pinch roll, r is the radius of the lower roll of the pinch roll, and d 1 、d 2 are the diameters at the bearings of the upper and lower rolls of the pinch roll respectively.

[0069] By determining the magnitude of the tension value within the above range, a series of tension values can be obtained. Through the method provided by the present invention, the relationship between the tension value and the contact width obtained by finite element can be obtained; then, according to the relationship between the roll profile of the pinch roll and the contact width obtained by finite element simulation, the relationship between the tension value and the roll profile of the pinch roll can be finally obtained, a series of suitable roll profiles of the pinch roll can be obtained, and finally a series of suitable roll types of the pinch roll can be determined.

[0070] Example 1:

[0071] S1: Using a sixth-degree curve, a finite element model is established to obtain the width values of the contact between the pinch roll and the strip, which are the upper roll width value L 1 , and the lower roll width value L 2 ;

[0072] S2: According to the characteristics of the pinch process and coiling, a calculation model for the roll profile of the pinch roll is established, including:

[0073] S21: Obtain the geometric parameters of the pinch roll, including the radii of the upper and lower rolls of the pinch roll and the horizontal offset angle β of the center of the circle calculated according to the positions of the lower roll of the pinch roll and the coiler, and the diameters d 1 、d 2 at the bearings of the upper and lower pinch rolls. In this example, the radius of the upper roll R = 450 mm, the radius of the lower roll r = 250 mm, the horizontal offset angle of the center of the circle β = 13°, d 1 = 270 mm, d 2 = 150 mm.

[0074] S22: Obtain the on-site measured values during the pinch process of the pinch roll, including:

[0075] The distance value H from the center of the upper pinch roll to the upper surface of the strip 1 , the distance value H from the center of the lower pinch roll to the lower surface of the strip 2 , and the pressure N of the upper roll on the strip 1 、the pressure N of the lower roll on the strip 2 . In this embodiment, the strip thickness is calculated as h = 25 mm, H 1 = 430 mm, H 2 = 245 mm, N 1 = N 2 = 2.544 t

[0076] It can be obtained that:

[0077] L 上 = [arccos(H 1 / R) - β]R = 10.4 mm

[0078] L 下 = [arccos(H 2 / r) + β]r = 34 mm

[0079] S23: Using the adhesion friction theory to obtain the relationship between the frictional force and the contact area, the theoretical parameters that need to be obtained first include the shear strength τ of the adhesion nodes b , the sliding friction coefficient μ between the strip and the pinch roll, the friction coefficient μ at the bearings of the upper and lower pinch rolls 1 , and the rolling friction coefficient f between the strip and the pinch roll. In this embodiment, τ b = 178 MPa, μ is taken as 0.2 - 0.3, μ 1 is taken as 0.004, and f is taken as 0.2.

[0080] Combining the L 1 、L 2 values obtained in the finite element to get the tension T:

[0081] T = [arccos(H 1 / R) - β]RL 1 τ b + [arccos(H 2 / r) + β]RL 2 τ b - F H

[0082] where F H is obtained according to the tension in the finishing process.

[0083] The appropriate tension range is obtained by comparing through the following formula:

[0084] T 0□T□(N 1 +N 2 )μ-N 1 / R(f + μ 1 d 1 / 2)-N 2 / r(f + μ 1 d 2 / 2)

[0085] Wherein, T 0 is the minimum tension value required by the factory, and the tension values can be compared for different roll profiles.

[0086] Therefore, the pinch roll profile designed in this embodiment fits the roll profile curve with a sixth-order curve. As Figure 2 shown, the specific parameters are used to obtain reasonable roll profile curve parameter values through finite element simulation, and thus the pinch roll profile design can be completed. Among them, the mark 1 represents the sixth-order curve roll type of the roll.

[0087] Preferably, the embodiment of the present invention also provides a system for determining the pinch roll profile, including: a processor and a memory for storing executable instructions, wherein the processor is configured to execute the executable instructions to perform the method for determining the pinch roll profile of the present invention.

[0088] Preferably, the embodiment of the present invention also provides a computer storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the method for determining the pinch roll profile of the present invention.

[0089] The above description shows and describes several preferred embodiments of the present invention. However, as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for determining the shape of pinch rolls, characterized in that, comprising: S1. Obtain the contact width and contact length between the pinch rolls and the strip steel. Among them, the contact width L between the upper pinch roll and the strip steel 1 and the contact width L between the lower pinch roll and the strip steel 2 are obtained by using a sixth-degree curve to establish a finite element model of the pinch roll profile; the contact length of the upper roll of the pinch roll is: L 上 = [arccos(H 1 / R) - β]R; The contact length of the lower roll of the pinch roll is: L 下 = [arccos(H 2 / r) + β]r, Among them, H 1 is the distance value from the center of the upper roll of the pinch roll to the upper surface of the strip steel, and H 2 is the distance value from the center of the lower roll of the pinch roll to the lower surface of the strip steel. β is the angle between the line connecting the center of the lower roll of the pinch roll and the center of the coiler and the horizontal direction; S2. Obtain the contact area between the pinch roll and the strip steel based on the contact width and contact length, and the contact area between the upper roll of the pinch roll and the strip steel is L 上 L 1 ; The contact area between the lower pinch roll and the strip steel is L 下 L 2 ; S3. Obtain the frictional force of the pinch roll according to the contact area, where the frictional force of the upper roll of the pinch roll is: F 1 = L 上 L 1 τ b ; the frictional force of the lower roll of the pinch roll is: F 2 = L 下 L 2 τ b τ b is the shear strength; S4. Obtain the tension of the strip steel according to the frictional force: T = F 1 + F 2 - F H = L 上 L 1 τ b + L 下 L 2 τ b - F H , F H represents the sliding frictional force of the finishing rolls, and the condition satisfied by the tension T is: T 0 ≤T≤(N 1 +N 2 )μ - N 1 / R(f + μ 1 d 1 / 2) - N 2 / r(f + μ 1 d 2 / 2), where T 0 is the minimum required tension of the steel mill, N 1 , N 2 are the clamping forces of the upper and lower rolls of the pinch roll on the strip respectively; μ is the sliding friction coefficient between the strip and the pinch roll; μ 1 is the friction coefficient at the bearings of the upper and lower rolls of the pinch roll; f is the rolling friction coefficient between the strip and the pinch roll, R is the radius of the upper roll of the pinch roll, r is the radius of the lower roll of the pinch roll, d 1 , d 2 are the diameters at the bearings of the upper and lower rolls of the pinch roll respectively; Determine the magnitude of the tension value within the above range, that is, obtain a series of tension values. From the relationship between the tension value and the contact width obtained by the finite element method, and then according to the relationship between the shape of the pinch roll and the contact width obtained by finite element simulation, finally obtain the relationship between the tension value and the shape of the pinch roll, that is, finally determine a series of shapes of the pinch rolls.

2. The method for determining the shape of the pinch roll according to claim 1, characterized in that, the maximum value of the tension satisfies that the strip steel does not slip when moving in the pinch roll.

3. A system for determining the shape of the pinch roll, characterized in that, comprising: a processor and a memory for storing executable instructions, wherein the processor is configured to execute the executable instructions to perform the method for determining the shape of the pinch roll according to any one of claims 1-2.

4. A computer storage medium, characterized in that, a computer program is stored on the storage medium, and the computer program is executed by a processor to implement the method for determining the shape of the pinch roll according to any one of claims 1-2.

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