Method for eliminating thin strip fold in an annealing furnace

Abstract

The application relates to an annealing furnace in-batch thin strip fold mark eliminating method, which comprises the following steps: dividing an annealing furnace in-batch into processing sections; obtaining actual tension of a thin strip of each processing section; determining a fold mark defect occurrence area according to the actual tension of the thin strip; adjusting a running parameter of the thin strip in the fold mark defect occurrence area; and adjusting a running parameter of the thin strip in an adjacent area of the fold mark defect occurrence area. The annealing furnace in-batch thin strip fold mark eliminating method provided by the application is based on the current situation that it is difficult to install a tension adjusting device due to the large length of the annealing furnace and the high temperature in the furnace, correctly utilizes the influence of the slow cooling section furnace roller rotating speed, relieves the disadvantage of low tension in the middle part of the annealing furnace, and achieves the purpose of eliminating the fold mark defects in the furnace.

Description

Technical Field

[0001] This application relates to the field of cold rolling of silicon steel, and more particularly to a method for eliminating creases in thin strips inside an annealing furnace. Background Technology

[0002] High-grade non-oriented silicon steel needs to be annealed in a horizontal continuous annealing furnace after cold rolling. Due to the structural characteristics of the horizontal annealing furnace, crease defects often appear in ultra-thin strip steel (hereinafter referred to as thin strip) after annealing, especially in the later stage of the annealing furnace operation.

[0003] Creases prevent silicon steel laminations from fitting tightly, reducing their magnetic permeability and increasing energy consumption. Additionally, tiny gaps between the laminations can cause low-amplitude, high-frequency vibrations, generating noise. Therefore, improvements are needed. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this application provides a method for eliminating thin strip creases in an annealing furnace.

[0005] In a first aspect, this application provides a method for eliminating creases in a thin strip inside an annealing furnace, the method comprising the steps of:

[0006] Divide the annealing furnace into processing sections;

[0007] Obtain the actual tension of the thin strip in each of the processing segments;

[0008] The area where the crease defect occurs is determined based on the actual tension of the thin strip.

[0009] Adjust the operating parameters of the thin strip within the area where the crease defect occurs;

[0010] Adjust the operating parameters of the thin strip in the area adjacent to the area where the crease defect occurs.

[0011] Preferably, the step of dividing the annealing furnace into processing sections includes the following steps:

[0012] Obtain the furnace temperature of the annealing furnace;

[0013] The annealing furnace is divided into a preheating section, a heating section, a homogenizing section, a slow cooling section, and a cooling section according to the furnace temperature.

[0014] Preferably, the temperature of the preheating section is 150℃-250℃.

[0015] Preferably, the temperature of the heating section is 600℃-900℃.

[0016] Preferably, the temperature of the heat spreader is 850℃-1000℃.

[0017] Preferably, the temperature of the slow cooling section is 600℃-800℃.

[0018] Preferably, the expression for the actual tension of the thin strip is:

[0019] F = T - nf;

[0020] Where F represents the actual tension of the strip, T represents the tension inside the furnace, n represents the number of furnace rollers, and f represents the frictional force of a single furnace roller on the strip.

[0021] Preferably, the area where the crease defect occurs is a heat-equalizing zone, and the area adjacent to the area where the crease defect occurs is a slow-cooling zone.

[0022] Preferably, adjusting the operating parameters of the thin strip within the area where the crease defect occurs includes the following steps:

[0023] Increase the tension of the thin strip in the heat spreader section.

[0024] Preferably, adjusting the operating parameters of the thin strip in the region adjacent to the crease defect area includes the following steps:

[0025] Increase the running speed of the thin belt in the slow cooling section;

[0026] Increase the rotational speed of the furnace rollers in the slow cooling section.

[0027] The technical solutions provided in this application have the following advantages compared with the prior art:

[0028] This application provides a method for eliminating thin strip creases inside an annealing furnace. Based on the current situation where the annealing furnace has a large length span and the furnace temperature is high, making it difficult to install tension adjustment equipment, this method correctly utilizes the influence of the furnace roller speed in the slow cooling section, alleviates the disadvantage of low tension in the middle of the annealing furnace, and achieves the purpose of eliminating crease defects inside the furnace. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating a method for eliminating creases in a thin strip inside an annealing furnace, provided as an embodiment of this application;

[0032] Figure 2This is a schematic diagram illustrating the division of the internal processing sections of an annealing furnace in a method for eliminating thin strip creases inside an annealing furnace, as provided in an embodiment of this application.

[0033] Figure 3 A schematic diagram of the stress on the strip inside the annealing furnace in a method for eliminating creases in thin strips provided in this application embodiment;

[0034] Figure 4 A schematic diagram of the action of furnace rollers on the strip in an annealing furnace according to an embodiment of this application;

[0035] Figure 5 A schematic diagram of a double-cone furnace roller in a method for eliminating thin strip creases inside an annealing furnace, provided in an embodiment of this application;

[0036] Figure 6 This is a schematic diagram of the conical roller effect in a method for eliminating thin strip creases in an annealing furnace, as provided in an embodiment of this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Figure 1 This is a schematic flowchart illustrating a method for eliminating creases in a thin strip inside an annealing furnace, as provided in an embodiment of this application.

[0039] This application provides a method for eliminating creases in thin strips inside an annealing furnace, the method comprising the following steps:

[0040] S1: Divide the annealing furnace into processing sections;

[0041] In this embodiment of the application, the step of dividing the annealing furnace into processing sections includes:

[0042] Obtain the furnace temperature of the annealing furnace;

[0043] The annealing furnace is divided into a preheating section, a heating section, a homogenizing section, a slow cooling section, and a cooling section according to the furnace temperature.

[0044] Specifically, such as Figure 2 The temperature inside the annealing furnace is detected by temperature detection equipment, and the furnace is divided into preheating section, heating section, soaking section, slow cooling section and cooling section according to the temperature.

[0045] In this embodiment of the application, the temperature of the preheating section is 150℃-250℃.

[0046] In this embodiment of the application, the temperature of the heating section is 600℃-900℃.

[0047] In this embodiment of the application, the temperature of the heat exchange zone is 850℃-1000℃.

[0048] In this embodiment of the application, the temperature of the slow cooling section is 600℃-800℃.

[0049] S2: Obtain the actual tension of the thin strip in each of the processing segments;

[0050] Specifically, the crease defects inside the furnace mainly exhibit shapes such as "semi-U-shaped" and "oblique line," which are traces left by the folding of the thin strip inside the furnace. The folding is caused by the thin strip being crushed when it passes over the furnace roller after bending. Therefore, bending inside the furnace is the direct cause of the crease defects. Analysis shows that bending is the result of the combined effect of the following three factors: (1) high temperature makes the thin strip more prone to deformation; (2) slow oxidation causes the ends of the furnace rollers to taper, such as... Figure 5 As shown, the taper generates torque on the thin strip (tapered roller effect), as... Figure 6 As shown; (3) The thin strip is subjected to less tension, and the thin strip is more prone to warping when the tension is smaller. The edge of the thin strip is located in the taper area of ​​the furnace roll. Under the action of the tapered roll effect, it moves laterally inward, while the thin strip in the middle is not subjected to lateral force, which will hinder the edge from moving laterally inward. The two are in opposition, and thus a circular arc-shaped warping in the shape of the furnace roll profile is formed on the furnace roll, leaving a "semi-U" shaped crease. When it is less severe, it is in the shape of a "slanted line", such as Figure 4 As shown.

[0051] Due to the requirements of the silicon steel annealing process, the furnace temperature and the shape of the furnace rolls cannot be arbitrarily changed, so the only way to eliminate creases is to increase the tension inside the furnace. However, directly increasing the set value T of the furnace tension will cause the thin strip inside the furnace to be narrowed and deformed, resulting in internal structural distortion and deterioration of the silicon steel properties. Therefore, it is necessary to find the source of the crease defect and specifically increase the tension in a local area inside the furnace.

[0052] Step S1 reveals that the soaking zone has the highest temperature, making the thin strip most prone to deformation in this area. Simultaneously, the soaking zone is located in the middle of the annealing furnace, and the number of furnace rollers (n) between this zone and the tension rollers is the largest. The furnace rollers exert a positive frictional force on the thin strip. Let f be the frictional force of a single furnace roller on the thin strip, and T be the tension within the furnace. Then, the expression for the actual tension of the thin strip in a certain area of ​​the furnace is:

[0053] F = T - nf;

[0054] Where F represents the actual tension of the strip, T represents the tension inside the furnace, n represents the number of furnace rollers, and f represents the frictional force of a single furnace roller on the strip.

[0055] S3: Determine the area where the crease defect occurs based on the actual tension of the thin strip;

[0056] Specifically, by comprehensively comparing the actual tension of the thin strip in each processing section, the actual tension of the thin strip in the heat soaking section is the smallest. Therefore, the area where the crease defect occurs is the heat soaking section, and the area adjacent to the area where the crease defect occurs is the slow cooling section.

[0057] S4: Adjust the operating parameters of the thin strip within the area where the crease defect occurs;

[0058] In this embodiment of the application, adjusting the operating parameters of the thin strip within the area where the crease defect occurs includes the following steps:

[0059] Increase the tension of the thin strip in the heat spreader section.

[0060] Specifically, increasing the tension of the thin strip in the heat-soaking section can eliminate crease defects.

[0061] S5: Adjust the operating parameters of the thin strip in the area adjacent to the area where the crease defect occurs.

[0062] In this embodiment of the application, adjusting the operating parameters of the thin strip in the region adjacent to the crease defect area includes the following steps:

[0063] Increase the running speed of the thin belt in the slow cooling section;

[0064] Increase the rotational speed of the furnace rollers in the slow cooling section.

[0065] Specifically, increasing the running speed of the thin strip in the slow cooling section can provide traction force for the thin strip in the heat soaking section, thereby increasing the tension in the heat soaking section; since the thin strip begins to cool down in the slow cooling section, its hardness and toughness gradually increase, so appropriately increasing the speed of the furnace rollers in the slow cooling section will not scratch the surface of the thin strip.

[0066] In some examples, the rotational speed of the first to third furnace rolls in the slow cooling section is increased by 8%, the rotational speed of the fourth to sixth furnace rolls is increased by 10%, and the rotational speed of the seventh to tenth furnace rolls is increased by 11%. By gradually increasing the rotational speed of the furnace rolls in the slow cooling section, the crease defect can be effectively eliminated.

[0067] This application provides a method for eliminating thin strip creases inside an annealing furnace. Based on the current situation where the annealing furnace has a large length span and the furnace temperature is high, making it difficult to install tension adjustment equipment, this method correctly utilizes the influence of the furnace roller speed in the slow cooling section, alleviates the disadvantage of low tension in the middle of the annealing furnace, and achieves the purpose of eliminating crease defects inside the furnace.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for eliminating creases in thin strips inside an annealing furnace, characterized in that, The method includes the following steps: Divide the annealing furnace into processing sections; Obtain the actual tension of the thin strip in each of the processing segments; The area where the crease defect occurs is determined based on the actual tension of the thin strip. Adjust the operating parameters of the thin strip within the area where the crease defect occurs; Adjust the operating parameters of the thin strip in the area adjacent to the crease defect area; The process of dividing the annealing furnace into processing sections includes the following steps: Obtain the furnace temperature of the annealing furnace; The annealing furnace is divided into a preheating section, a heating section, a soaking section, a slow cooling section, and a cooling section according to the furnace temperature. The temperature of the preheating section is 150℃-250℃; The temperature of the heating section is 600℃-900℃; The temperature of the heat spreader is 850℃-1000℃; The temperature of the slow cooling section is 600℃-800℃; The expression for the actual tension of the thin strip is: F = T - nf; Where F represents the actual tension of the strip, T represents the tension inside the furnace, n represents the number of furnace rollers, and f represents the frictional force of a single furnace roller on the strip; The area where the crease defect occurs is a heat-equalizing zone, and the area adjacent to the area where the crease defect occurs is a slow-cooling zone; The adjustment of the thin strip operating parameters within the area where the crease defect occurs includes the following steps: Increase the tension of the thin strip in the heat spreader section; The steps of adjusting the thin strip operating parameters in the area adjacent to the crease defect area include: Increase the running speed of the thin belt in the slow cooling section; Increase the rotational speed of the furnace rollers in the slow cooling section.

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