A method for improving the stiffness of a four-high rolling mill

Abstract

The present invention relates to the technical field of four-high rolling mills, and particularly relates to a method for improving the stiffness of a four-high rolling mill, comprising the following steps: S1, stiffness measurement; S2, stiffness analysis; S3, roll assembly; S4, housing measurement; S5, gap management; S6, cycle management. The present invention can accurately diagnose and lock abnormal components causing stiffness deterioration in a complex rolling mill system, realizing accurate tracing of the causes of stiffness deterioration of the rolling mill; by replacing or repairing key control elements of the abnormal components, the present invention quickly restores and improves the stiffness of the rolling mill, ensuring the stability of rolling and the product accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of four-high rolling mills, and particularly relates to a method for improving the stiffness of a four-high rolling mill. Background Art

[0002] The core equipment of plate production lines such as medium plate production lines, Steckel rolling production lines, and hot strip rolling production lines is the four-high rolling mill. The steel billet is rolled and deformed by the rolls of the four-high rolling mill and extended into a finished steel plate with the required thickness, structure, and performance. During the rolling process, the huge rolling force acts on the rolling mill body and the roll system in the opposite direction, causing springback. The index that affects the springback of the rolling mill is stiffness. The design comprehensive stiffness of modern four-high plate rolling mills is generally between 600 - 950 t / mm, and the maximum rolling force is between 7000 - 9000 t. For the comprehensive stiffness of the rolling mill, the higher the comprehensive stiffness, the smaller the springback of the rolls during the rolling process, and the easier it is to control the thickness. The smaller the deviation of the sub-stiffness between the operator side and the drive side of the rolling mill, the smaller the springback deviation on both sides, and the smaller the thickness deviation in the transverse direction of the steel plate. Stable and high-precision rolling has very strict requirements not only for the comprehensive stiffness of the rolling mill but also for the sub-stiffness of the operator side and the drive side. The change of stiffness will directly affect the calculation of the model and ultimately affect the dimensional accuracy of the product. In severe cases, it will cause unstable rolling, resulting in defective products and accidents.

[0003] The components that affect the stiffness of the rolling mill include: backup roll assembly, work roll assembly, mechanical screwdown device, hydraulic HGC, housing and connecting beam, etc. Wear, increased clearance, deviation of the spatial position and the force application point inside and outside each component will affect the comprehensive stiffness, resulting in a larger deviation of the stiffness between the drive side and the operator side, affecting the control of the product dimensional accuracy, the production of limit specifications, and the operability. These adverse changes are difficult to trace, becoming a difficult problem in the stiffness management of the rolling mill. Summary of the Invention

[0004] Aiming at the technical problem that the stiffness of the four-high rolling mill is difficult to manage, the present invention provides a method for improving the stiffness of the four-high rolling mill, which can effectively improve the stiffness of the four-high rolling mill and keep the stiffness of the rolling mill at a better level.

[0005] The present invention provides a method for improving the stiffness of a four-high rolling mill, including the following steps:

[0006] S1. Stiffness measurement: After replacing the backup roll or work roll of the four-high rolling mill, perform a press calibration, and use the calibration data to fit the curves of the comprehensive stiffness, the stiffness of the operator side and the drive side at different rolling forces respectively;

[0007] S2. Stiffness analysis: According to the comprehensive stiffness fitting curve, evaluate the comprehensive state of the rolling mill and the roll system; according to the deviation of the stiffness fitting curves of the operator side and the drive side, determine the abnormal unit of the rolling mill or the roll system;

[0008] S3. Roll Assembly: Based on the identified abnormal unit of the rolling mill or roll train, check item by item according to the control elements of backup roll assembly and work roll assembly to determine the abnormal parts or components.

[0009] S4. Housing Measurement: Use laser tracking measurement technology to measure the spatial position of the mating slide plates of the work rolls and backup rolls on the housing and the screw-down system, and correct the deviation according to the measurement.

[0010] S5. Clearance Management: Evaluate the parallelism of the slide plates and the self-aligning surface of the screw-down.

[0011] S6. Period Management: Establish the correspondence between the real-time state of the physical object and the stiffness curve, set the measurement period for data measurement and tracking, form an analysis of the wear and deterioration trend, and accurately lock the abnormal unit.

[0012] Further, in step S1, when the maximum rolling force of the four-high rolling mill is 9000t, the calibration pressing force for calibration is above 5000t; when the maximum rolling force of the four-high rolling mill < 9000t, the calibration pressing force for calibration is greater than 60% of the maximum rolling force.

[0013] Further, in step S3, the control elements of backup roll assembly are, in sequence: locking of the taper sleeve, locking of the bearing housing, wear of the pressure pad, wear of the slide plate, wear of the seal, and fastening of the gland and end cover.

[0014] Further, in step S3, the control elements of work roll assembly are four-row tapered roller bearings, clearance of the thrust bearing, wear of the large-surface slide plate, wear of the bending roll self-aligning slider, wear of the shaft-end slide plate, deformation of the dowel pin, clearance and level of the small guard plate.

[0015] Further, in step S4, when measuring the spatial position of the mating slide plates of the work rolls and backup rolls on the housing, ensure that the centerlines of the roll train are coplanar and there is no intersection.

[0016] Further, in step S4, when measuring the screw-down system, ensure that the cylindrical pads of the screw-down system are not allowed to be unevenly worn, ground flat, or cracked, and there are no steps on the mating surface of the spherical pads of the screw-down.

[0017] Further, in step S5, when evaluating the parallelism of the slide plates, evaluate the spatial parallelism and reference deviation of the slide plates on the work roll outlet side and backup roll inlet side of the housing.

[0018] Further, in step S5, when evaluating the self-aligning surface of the screw-down, evaluate the abnormal self-aligning surface of the spherical pads of the screw-down and cylindrical pads of the backup roll, the influence on the load distribution of the oil film bearing under large rolling force, and the eccentric load on the four-row tapered roller bearings caused by the wear of the self-aligning blocks of the work rolls.

[0019] Further, in step S6, the real-time state of the physical object includes the real-time states of the backup rolls, work roll bearing housings, screw-down lead screw nuts, spherical pads, housing slide plates, roll train slide plates, self-aligning blocks, and housing clearances.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The present invention can accurately diagnose and lock abnormal components causing the deterioration of the rolling mill stiffness from a complex rolling mill system, realizing accurate tracing of the reasons for the deterioration of the rolling mill stiffness;

[0022] (2) By replacing or repairing the key control elements of the abnormal components, the present invention can quickly restore and improve the rolling mill stiffness, ensuring the stability of rolling and the product precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is the comprehensive stiffness fitting curve of Embodiment 1 of the specific implementation mode of the present invention.

[0025] Figure 2 It is the sub-stiffness fitting curve of Embodiment 1 of the specific implementation mode of the present invention.

[0026] Figure 3 It is the sub-stiffness fitting curve of Embodiment 2 of the specific implementation mode of the present invention.

[0027] Figure 4 It is the sub-stiffness fitting curve under another abnormal unit of Embodiment 2 of the specific implementation mode of the present invention. SPECIFIC IMPLEMENTATION MODE

[0028] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Embodiment 1

[0030] A method for improving the stiffness of a four-high rolling mill includes the following steps:

[0031] (1) Stiffness measurement

[0032] After replacing the backup roll or work roll of the four-high rolling mill, a long calibration (pressing calibration) is carried out. For a coil mill with a maximum rolling force of 9000t, the calibration pressing force needs to reach more than 5000t. After calibration, the calibrated data is exported and the stiffness curve fitting is carried out through setting formulas using EXCEL software to fit out the comprehensive stiffness curve and the sub-stiffness curve. The comprehensive stiffness curve is as shown in Figure 1 as shown. The sub-stiffness curve is as shown in Figure 2 as shown.

[0033] (2) Stiffness analysis

[0034] Figure 1 This is also the comprehensive stiffness fitting curve made for the new equipment. This rolling mill is designed with a stiffness of 900t / mm, and the measured maximum stiffness reaches 930t / mm. Figure 1 In Figure 2 the stiffness curve slowly rises with the increase of the pressing force, gradually reaches the maximum value and remains basically stable, and the state is relatively ideal; in

[0035] the sub-stiffness curve is divided into the operating side (OS) stiffness curve and the drive side (DS) stiffness curve. When the total pressing force is 5000t (2500t on one side), the operating side kinks downwards, and the stiffness value deviates from that of the drive side. This deviation is abnormal, and the bearing housing on the operating side, EGC, etc. are identified as possible abnormal units.

[0036] (3) Roll assembly

[0037] Roll assembly includes backup roll assembly and work roll assembly. Among them, the contribution of the backup roll assembly to stiffness is greater than that of the work roll assembly. For different roll assemblies, key influencing factor inspection elements are formulated. In the case of locking the abnormal bearing housing, check and measure item by item according to the preset inspection elements to find the abnormal parts or components.

[0038] The key control elements of the backup roll assembly are: cone bushing locking, bearing housing locking, pressure pad wear, slide plate wear, seal wear, cover end cover fastening;

[0039] The key control elements of the work roll assembly are: four-row tapered roller bearings, thrust bearing clearance, large surface slide plate wear, bending roll self-aligning slider wear, shaft end slide plate wear, stud deformation, small guard plate clearance and level.

[0040] (4) Housing measurement

[0041] The gap measurement of the arch adopts laser tracking measurement technology to measure the spatial position of the arch working roll and support roll matching the slide plane to ensure that the center lines of the roll system are coplanar and there is no intersection. The existence of crossed rolls will generate axial force during steel rolling, which will be manifested as the roll system bending under force during calibration. The cylindrical pad of the press-down system is not allowed to be worn, flattened, or cracked, and the mating surface of the press-down spherical pad is not allowed to have steps.

[0042] (5) Gap management

[0043] The gap management technology mainly manages the parallelism of the slide plate and the pressing self-positioning surface.

[0044] The parallelism of the slide plate mainly evaluates the spatial parallelism and reference deviation of the arch slide plate on the working roll outlet side and the support roll inlet side.

[0045] The pressing down self-positioning surface mainly manages the abnormal self-positioning surface of the pressing down spherical pad and the supporting roller cylindrical pad, which affects the load distribution of the oil film bearing under large rolling force and the wear of the working roll self-positioning block, causing the unbalanced load of the four-row tapered bearing.

[0046] (6) Cycle Management

[0047] The comparative difference method is used to analyze stiffness, which requires a large number of different combinations of stiffness curves and the real-time status of each physical unit. The cycle management technology is to establish the corresponding relationship between the real-time status of the physical object and the stiffness curve, including support rollers, work roller bearing seats, screw nuts, spherical pads, arch slides, roller slides, self-positioning blocks, arch gaps, etc. By setting a reasonable measurement cycle to implement data measurement and tracking, a wear degradation trend analysis is formed. The richer the data, the easier it is to find the causal relationship between these periodic measurement data and stiffness differences, and accurately lock the abnormal units.

[0048] Example 2

[0049] Different from Example 1, in step (1) of Example 1, the actual calibration will produce various stiffness curves, such as Figure 3 , Figure 4 To identify the abnormal components in the abnormal unit, the stiffness analysis comparison difference method is adopted. It is necessary to record and track the status of each unit, and lock the abnormal unit through a large number of test curve analogies.

[0050] The method for improving the rigidity of the four-roller rolling mill of the present invention organically combines six technologies, namely rigidity measurement, rigidity analysis, roll assembly, arch measurement, gap management and cycle management, none of which can be missing. Rigidity measurement technology is the premise, rigidity analysis technology is the judgment standard, cycle management technology is the method, and roll assembly technology, arch measurement technology and gap management technology are the means.

[0051] The present invention can accurately diagnose and lock the abnormal components that cause the deterioration of the rolling mill stiffness from a complex rolling mill system, and realize accurate tracing of the causes of the deterioration of the rolling mill stiffness;

[0052] By replacing or repairing the key control elements of the abnormal components, the present invention quickly restores and improves the stiffness of the rolling mill, ensuring the stability of rolling and the product accuracy.

[0053] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A method for improving the stiffness of a four-high rolling mill, characterized in that, It includes the following steps: S1. Stiffness measurement: After replacing the backup roll or work roll of the four-high rolling mill, carry out the nip calibration, and use the calibration data to fit the curves of the comprehensive stiffness, the stiffness on the operator side and the drive side at different rolling forces respectively; S2. Stiffness analysis: Evaluate the comprehensive state of the rolling mill and the roll system according to the comprehensive stiffness fitting curve; Determine the abnormal units of the rolling mill or the roll system according to the deviation of the stiffness fitting curves on the operator side and the drive side; S3. Roll assembly: According to the determined abnormal units of the rolling mill or the roll system, check item by item according to the control elements of the backup roll assembly and the control elements of the work roll assembly to determine the abnormal parts or components; S4. Housing measurement: Adopt the laser tracking measurement technology to measure the spatial position of the mating slide plate plane of the work roll and the backup roll of the housing and the screw-down system, and correct the deviation according to the measurement; S5. Clearance management: Evaluate the parallelism of the slide plate and the self-leveling of the screw-down; S6. Period management: Establish the correspondence between the real-time state of the physical object and the stiffness curve, set the measurement period to carry out data measurement and tracking, form the wear and deterioration trend analysis, and accurately lock the abnormal units.

2. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S1, when the maximum rolling force of the four-high rolling mill is 9000t, the calibration nip force for nip calibration is above 5000t; When the maximum rolling force of the four-high rolling mill < 9000t, the calibration nip force for nip calibration is greater than 60% of the maximum rolling force.

3. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S3, the control elements of the backup roll assembly are in turn: locking of the taper sleeve, locking of the bearing housing, wear of the pressure pad, wear of the slide plate, wear of the seal, fastening of the through cover and end cover.

4. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S3, the control elements of the work roll assembly are the clearance of the four-row tapered roller bearing and the thrust bearing, wear of the large surface slide plate, wear of the bending roll self-aligning slider, wear of the shaft end slide plate, deformation of the dowel pin, clearance and level of the small guard plate.

5. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S4, measure the spatial position of the mating slide plate plane of the work roll and the backup roll of the housing to ensure that the centerlines of the roll system are coplanar and there is no intersection.

6. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S4, measure the screw-down system to ensure that the cylindrical pad of the screw-down system is not allowed to be unevenly worn, ground flat or cracked, and there are no steps on the mating surface of the screw-down spherical pad.

7. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S5, the parallelism of the slide plate evaluates the spatial parallelism and reference deviation of the slide plates of the work roll outlet side and the backup roll inlet side of the housing.

8. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S5, the self-leveling of the screw-down evaluates the self-leveling abnormality of the screw-down spherical pad and the cylindrical pad of the backup roll, the influence on the load distribution of the oil film bearing under large rolling forces, and the eccentric load on the four-row tapered roller bearing caused by the wear of the self-aligning block of the work roll.

9. The method for improving the stiffness of a four-high rolling mill according to claim 1, characterized in that, In step S6, the real-time state of the physical object includes the real-time states of the backup roll, the bearing housing of the work roll, the screw and nut of the screw-down, the spherical pad, the slide plate of the housing, the slide plate of the roll system, the self-aligning block, and the clearance of the housing.

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