A method for eliminating local warping of strip steel

Abstract

This application relates to the technical field of steel rolling technology and discloses a method for eliminating local warping of steel strips. The method comprises: obtaining the actual thickness value of the steel strip in real time; determining the range of the actual thickness value, and determining that the local actual thickness value range is within a preset threshold value as a warped thickness value; when the actual thickness value is a warped thickness value, setting the flattening force and front-to-back tension according to the steel grade and specifications of the steel strip; setting the bending roll force according to the steel grade and specifications of the steel strip and the warped thickness value; setting the rolling force according to the steel grade and specifications of the steel strip; and flattening the steel strip according to the flattening force, front-to-back tension, bending roll force, and rolling force. This method further improves the cross-sectional profile quality of the steel strip, prevents ribs from occurring during the subsequent cold rolling process, and reduces the scrap rate of this process.

Description

Technical Field

[0001] The present application relates to the technical field of steel rolling technology, and in particular, to a method for eliminating local warping of steel strips. Background Art

[0002] The rapid development of my country's automotive, home appliance, and other manufacturing industries has led to a sharp increase in demand for cold-rolled steel, including cold-rolled and galvanized steel. This has also led to higher requirements for dimensional accuracy, surface quality, and performance. To reduce cold-rolled steel plate shape fluctuations and improve cold-rolled yields, hot-rolled base stock with a well-defined cross-sectional profile is required. Edge warping of hot-rolled base stock, where the thickness of the strip increases, can cause edge ribs during cold rolling, directly impacting cold-rolled plate shape quality.

[0003] There are many factors that cause the edge thickness of the strip to warp in the hot rolling process, including a large amount of same-width strip rolled, large local wear of the working rolls, and thick strip edge thickness; the planned reverse-width production, the width of the next roll of strip is greater than the width of the previous roll of strip, resulting in low temperature of the working rolls corresponding to the edge during the production of the next roll of strip, resulting in a thick edge problem; in addition, there are also reasons such as uneven thermal expansion of the working rolls, uneven wear, and small convexity calculated by the model. Technical and management problems can be improved through on-site research, but problems such as same-width scheduling and reverse-width scheduling affected by orders cannot be fundamentally solved. Summary of the Invention

[0004] The purpose of this application is to provide a method for eliminating local warping of the strip, further improve the cross-sectional profile quality of the strip, prevent the problem of ribs in the cold rolling production process of the next step, and reduce the scrap rate of this step.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0006] According to one aspect of an embodiment of the present application, a method for eliminating local warping of a steel strip is provided, the method comprising: acquiring an actual thickness value of the steel strip in real time; determining an interval of the actual thickness value, and determining a warping thickness value if the interval of the local actual thickness value is within a preset threshold; setting a flattening force and front and rear tensions according to the steel grade and specification of the steel strip when the actual thickness value is a warping thickness value; setting a bending roll force according to the steel grade and specification of the steel strip and the warping thickness value; setting a rolling force according to the steel grade and specification of the steel strip; and flattening the steel strip according to the flattening force, the front and rear tensions, the bending roll force, and the rolling force.

[0007] In some embodiments, in the interval of determining the actual thickness value, the method includes: measuring the actual thickness value of the steel strip using an IMS meter.

[0008] In some embodiments, the warping thickness of the steel strip is the warping thickness of the edge of the steel strip.

[0009] In some embodiments, in determining the interval of the actual thickness value, the method further includes: when the entire interval of the actual thickness value is less than a preset threshold, the steel strip skips flattening processing and enters the next process.

[0010] In some embodiments, in determining the interval of the actual thickness value, the method further includes: when the interval of the actual thickness value is greater than a preset threshold, downgrading the steel strip.

[0011] In some embodiments, when the actual thickness value is the reverse warping thickness value, in setting the flattening force and front and rear tensions according to the steel grade specification of the strip, the method further includes: obtaining a standard thickness value, calculating the difference between the standard thickness value and the reverse warping thickness value; obtaining the yield strength of the steel grade according to the steel grade specification, and calculating the corresponding flattening force based on the difference and the yield strength.

[0012] In some embodiments, the flattening force is proportional to the yield strength of the steel type, and the flattening force ranges from 200 to 450 tons.

[0013] In some embodiments, the front-to-back tension is proportional to the yield strength of the steel type, and the front-to-back tension ranges from 10 to 30 tons.

[0014] In some embodiments, the bending roller setting adopts negative bending.

[0015] In some embodiments, the bending roll force is proportional to the yield strength of the steel type, and the setting value of the bending roll force is between 0 and -100%.

[0016] Compared with the prior art, the technical solution of the present application has the significant beneficial effect of eliminating the problem of warped strip edge thickness by using reasonable process parameters in the leveling process. By setting reasonable parameters such as rolling force, bending roll force, and front-to-back tension, and utilizing the thinning characteristics of the four-roller leveler, while using different bending roll types to achieve different thinning amounts at different locations on the strip, the warped strip edge thickness is eliminated, thereby improving the cross-sectional profile of the strip and eliminating localized convex spots. This improves the cross-sectional profile quality of the strip, prevents ribs from occurring during the subsequent cold rolling process, and reduces the scrap rate of this process.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0019] Figure 1 shows a flow chart according to an embodiment of the present application;

[0020] Figure 2 A profile comparison curve diagram of a steel strip before and after flattening according to an embodiment of the present application is shown.

[0021] The description of the accompanying figures is as follows: 1. Contour curve before flattening; 2. Contour curve after flattening. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0023] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0024] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0025] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0026] According to some embodiments, Figure 1As shown, the present application provides a method for eliminating local warping of a steel strip, the method comprising: step S101, acquiring the actual thickness value of the steel strip in real time; step S102, determining the interval of the actual thickness value, and determining it as a warping thickness value if the interval of the local actual thickness value is within a preset threshold; step S103, when the actual thickness value is a warping thickness value, setting the flattening force and front and rear tension according to the steel grade specification of the steel strip; step S104, setting the bending roll force according to the steel grade specification of the steel strip and the warping thickness value; step S105, setting the rolling force according to the steel grade specification of the steel strip; step S106, flattening the steel strip according to the flattening force, the front and rear tension, the bending roll force and the rolling force.

[0027] Based on the above embodiment, in step S101, after the hot rolling mill produces the strip, the actual thickness of the strip is obtained in real time. This method includes using an IMS instrument to measure the actual thickness of the strip, which simplifies system maintenance, development, and use. In other embodiments, the IMS instrument can also be replaced with other thickness measuring instruments.

[0028] Furthermore, in step S102, the actual thickness value interval is determined. If the local actual thickness value interval is within a preset threshold, it is determined to be a warped thickness value. The preset threshold is between a minimum value A and a maximum value B. The values ​​of A and B can be changed to one or both values ​​according to actual needs, and the difference between A and B can also be changed according to actual needs. Furthermore, when measuring the thickness of the steel strip, the thickness of the strip mostly maintains the standard thickness value, but a small part may have local protrusions. When the actual thickness value interval of the measured local protrusion is within the preset threshold, the local protrusion is the above-mentioned warping and needs to be leveled.

[0029] Furthermore, in step S103, if the actual thickness is measured and confirmed to be within a preset threshold, indicating a warped thickness, the flattening force and front-to-back tension are set on the production equipment according to the steel grade and specifications of the strip. These forces are adjusted to the appropriate flattening force and front-to-back tension. Different steel grades and specifications require different flattening forces and front-to-back tensions.

[0030] Furthermore, in step S104, a bending roll force is set based on the steel grade and the warpage thickness of the strip. In some embodiments, the bending roll setting uses negative bending. The setting principle is that the larger the warpage thickness, the greater the bending roll force.

[0031] Furthermore, in step S105, the rolling force is set according to the steel grade and specification of the strip steel, so that steels of different steel grades and specifications correspond to their appropriate rolling forces, thereby improving the rolling quality.

[0032] Furthermore, in step S106, the strip is flattened according to the set flattening force, the front and rear tensions, the bending roll force, and the rolling force. After the flattening is completed, the next step is entered.

[0033] In some embodiments, the warping thickness of the steel strip is the warping thickness of the edge of the steel strip.

[0034] Through the leveling process, the problem of warped strip edge thickness is eliminated by adopting appropriate process parameters during the leveling process. By setting appropriate parameters such as rolling force, bending force, and front and rear tension, and leveraging the thinning characteristics of the four-high skin-pass mill, and using different bending configurations to achieve different thinning amounts at different locations on the strip, this problem is eliminated, improving the strip's cross-sectional profile and eliminating localized bulges. This improves the strip's cross-sectional profile quality, prevents ribs during the subsequent cold rolling process, and reduces the scrap rate in this process.

[0035] According to some embodiments, in step S102, in the determination of the interval of the actual thickness value, the method further includes: when the entire interval of the actual thickness value is less than a preset threshold, the strip skips flattening processing and enters the next process.

[0036] Based on the above embodiment, when the interval of the actual thickness value of the entire strip measured in real time is less than the preset threshold value, it is a normal thickness value and does not require flattening processing.

[0037] According to some embodiments, in step S102, in determining the interval of the actual thickness value, the method further includes: when the interval of the actual thickness value is greater than a preset threshold, downgrading the steel strip.

[0038] Based on the above embodiment, when the range of the actual thickness values ​​of the whole or part of the strip measured in real time is greater than the preset threshold, the strip is downgraded and can be sold to customers who do not have requirements for the range of the actual thickness values ​​of the strip, but not sold to customers who have requirements for the range of the actual thickness values ​​of the strip.

[0039] According to some embodiments, in step S103, when the actual thickness value is a reverse warping thickness value, the flattening force and front and rear tensions are set according to the steel grade specification of the strip, and the method further includes: obtaining a standard thickness value, calculating the difference between the standard thickness value and the reverse warping thickness value; obtaining the yield strength of the steel grade according to the steel grade specification, and calculating the corresponding flattening force based on the difference and the yield strength.

[0040] Based on the above embodiment, the standard thickness value is a pre-set overall thickness value for the strip. The difference between the standard thickness value and the warped thickness value is calculated, and this difference represents the warp height. Different steel grades have different yield strengths. The yield strength of the steel grade being processed is determined based on actual processing conditions, and the required flattening force is calculated based on this difference and the yield strength.

[0041] Furthermore, the flattening force is proportional to the yield strength of the steel grade, and the flattening force ranges from 200 to 450 tons.

[0042] Furthermore, the front-to-back tension is proportional to the yield strength of the steel type, and the range of the front-to-back tension is between 10 and 30 tons.

[0043] Furthermore, the bending roll force is proportional to the yield strength of the steel grade, and the setting value of the bending roll force is between 0 and -100%.

[0044] In some embodiments, as Figure 2 As shown, the finishing mill of the 2250mm hot rolling production line consists of six stands. Taking one roll of home appliance outer plate as an example, the steel grade is SDX51D, the specification is 5.5*1532mm, and the average local warping thickness is 15.5um, which is within the preset threshold. Therefore, it is determined to enter the leveling process. The leveling process uses a leveling force of 250 tons, a tension of 29 tons, and a negative bending of -54%. The maximum local warping thickness measured before leveling is 21um. After leveling, the local high point is reduced to 4um, meeting the requirements of the next process. The cross-sectional profile comparison diagram of the strip is shown in the figure below. Figure 2 As shown, this figure selects the adjacent strip profiles before and after leveling, and shows the profile curve 1 before leveling and the profile curve 2 after leveling.

[0045] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed herein.

[0046] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for eliminating local warping of strip steel, characterized in that: The method comprises: After the hot rolling mill produces the strip, the actual thickness of the strip is obtained in real time; Determining the interval of the actual thickness value, and determining that the local actual thickness value interval is within a preset threshold value is a reverse warping thickness value; When the actual thickness value is the reverse warping thickness value, the flattening force and the front and rear tension are set according to the steel grade and specification of the strip; Setting the bending roll force according to the steel grade and specification of the strip and the warping thickness value; Setting the rolling force according to the steel grade and specifications of the strip; performing flattening processing on the steel strip according to the flattening force, the front and rear tensions, the bending roll force and the rolling force; When the actual thickness value is a reverse warping thickness value, in setting the leveling force and the front and rear tension according to the steel grade and specification of the steel strip, the method further includes: Obtaining a standard thickness value, and calculating a difference between the standard thickness value and the reverse warping thickness value; Obtaining the yield strength of the steel grade according to the steel grade specification, and calculating the corresponding leveling force according to the difference and the yield strength; The bending roller is set to adopt negative bending; In the interval of determining the actual thickness value, the method further includes: When the overall actual thickness value range is less than a preset threshold, the strip skips the flattening process and enters the next process; The front-to-back tension is proportional to the yield strength of the steel type, and the range of the front-to-back tension is between 10 and 30 tons.

2. The method according to claim 1, characterized in that In the real-time acquisition of the actual thickness value of the steel strip, the method includes: The actual thickness of the strip is measured using an IMS instrument.

3. The method according to claim 1, characterized in that The warping thickness of the steel strip is the warping thickness of the edge of the steel strip.

4. The method according to claim 1, wherein In the interval of determining the actual thickness value, the method further includes: When the interval of the actual thickness value is greater than a preset threshold, the steel strip is downgraded.

5. The method according to claim 1, wherein The leveling force is proportional to the yield strength of the steel grade, and the leveling force ranges from 200 to 450 tons.

6. The method according to claim 1, wherein The bending roll force is proportional to the yield strength of the steel grade, and the setting value of the bending roll force is between 0 and -100%.

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