Method for accurately judging abnormal type of liquid level fluctuation of slab crystallizer

Abstract

The invention discloses a method for accurately judging the abnormal type of slab crystallizer liquid level fluctuation, and relates to the technical field of metallurgy. The method for accurately judging the abnormal type of the liquid level fluctuation of the slab crystallizer comprises the following specific operations: S1, in a slab casting process, when the fluctuation of the liquid level of the crystallizer is abnormal, selecting a data volume of about 0.5 hour in a data acquisition system of a continuous casting machine, and taking an abscissa as time; according to the method for accurately judging the abnormal type of the slab crystallizer liquid level fluctuation, the abnormal type of the crystallizer liquid level fluctuation in casting is accurately judged, corresponding treatment measures are taken in time, and the degradation loss of a high-quality steel casting blank and potential casting safety risks are greatly reduced; by processing and analyzing the real-time detection data of the liquid level of the crystallizer in casting, the abnormal type of the fluctuation of the liquid level of the crystallizer in casting can be accurately judged, post operators are guided to take corresponding treatment measures in time, and the quality degradation loss of high-quality steel and the casting safety risk can be remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for accurately judging the abnormal type of liquid level fluctuation in a slab crystallizer. Background Art

[0002] In slab continuous casting production, the fluctuation of the liquid level in the crystallizer directly affects the quality of the ingot and the safety of casting. When the fluctuation amplitude of the liquid level in the crystallizer exceeds 5mm, the possibility of the protective slag being involved increases, which can easily lead to inclusions on the surface of the ingot and affect the metallurgical properties of the slab. Studies have shown that reducing the fluctuation amplitude of the liquid level in the crystallizer is one of the effective measures to control metallurgical defects of the slab.

[0003] The factors that affect the liquid level fluctuation of the crystallizer are very complex, and they are related to the equipment status of the casting machine, process operation, flow accumulation, deviation flow, bulging, etc. If the liquid level of the crystallizer fluctuates too much, it will not only cause surface defects such as cracks and slag inclusions, but even cause slag rolling and steel leakage accidents in severe cases. Therefore, controlling the liquid level fluctuation of the crystallizer has always been the goal of continuous casting workers. In essence, there are two types of crystallizer liquid level fluctuations. One is that the crystallizer liquid level fluctuation changes the flux of molten steel in the crystallizer, such as bulging and flow accumulation; the other is that the crystallizer liquid level fluctuation does not change the flux of molten steel in the crystallizer, such as instantaneous flow, surface waves, etc. The formation mechanisms of these two types of liquid level fluctuations are completely different, and the corresponding treatment measures are also different. If the process data can be quickly and easily analyzed, the essential type of crystallizer liquid level fluctuation can be accurately identified, and then the crystallizer liquid level fluctuation can be quickly treated accordingly, which will significantly reduce the quality loss of the ingot and the casting risk, and create significant economic benefits.

[0004] The patent "A method for determining and grading the liquid level fluctuation of a slab crystallizer with high surface requirements" with application number CN202310027832.1 relates to a method for determining and grading the liquid level fluctuation of a slab crystallizer with high surface requirements, and belongs to the field of iron and steel metallurgy technology. The technical scheme of the present invention is: a corresponding model of liquid level fluctuation deviation and billet length is established through the continuous casting drawing speed and the crystallizer liquid level fluctuation measurement time; through the correspondence between the actual billet length and the billet drawing length model, the one-to-one correspondence between the liquid level fluctuation deviation data and the actual billet position is achieved, and the point and line connection between time and space in the production process is achieved; through the actual billet cutting length, the liquid level fluctuation deviation of each billet is statistically analyzed, and the liquid level fluctuation deviation of a single billet is determined and graded. The beneficial effect of the present invention is: the slag roll-type peeling defects of ultra-deep drawing steel plates with high surface requirements are controlled within the steel plant, so as to effectively prevent problematic billets from flowing into users and reduce users' quality complaints and quality objections.

[0005] After searching, the existing technology mainly matches the actual crystallizer liquid level fluctuation performance with the ingot, and classifies it according to the degree of liquid level fluctuation, but does not involve the judgment and timely treatment of the crystallizer liquid level fluctuation type. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the deficiencies in the prior art, the present invention provides a method for accurately determining the type of abnormal liquid level fluctuation in a slab crystallizer, thereby solving the problems existing in the prior art.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: a method for accurately judging the type of abnormal fluctuation of the liquid level of a slab crystallizer, the specific operation is as follows:

[0010] S1. During the slab casting process, when the crystallizer liquid level fluctuation is abnormal, about 0.5 hours of data is selected in the continuous casting machine data acquisition system, with the horizontal axis representing time and the vertical axis representing the crystallizer liquid level fluctuation value.

[0011] S2. Perform fast Fourier transformation on the selected data, that is, convert the signal value of the crystallizer liquid level fluctuation value from the time domain to the frequency domain, and set the output result to select a linear chart. At this time, the horizontal axis is frequency and the vertical axis is amplitude.

[0012] S3. When the calculation result graph is displayed as a "mountain" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is not changing the steel liquid flux in the crystallizer. When the calculation result graph is displayed as a "pointed" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is not changing the steel liquid flux in the crystallizer.

[0013] S4. For the abnormal crystallizer liquid level fluctuation whose essential type is not to change the molten steel flux in the crystallizer, timely treatment measures such as lowering the casting speed and reducing the amount of argon blowing on the stopper rod can be taken; for the abnormal crystallizer liquid level fluctuation whose essential type is to change the molten steel flux in the crystallizer, timely treatment measures such as feedforward control and increasing the amount of cooling water can be taken.

[0014] (III) Beneficial effects

[0015] The present invention provides a method for accurately judging the type of abnormal liquid level fluctuation in a slab crystallizer. It has the following beneficial effects:

[0016] The method for accurately judging the abnormal type of slab crystallizer liquid level fluctuation is to accurately judge the abnormal type of crystallizer liquid level fluctuation during casting, take corresponding disposal measures in time, and greatly reduce the degradation loss of high-quality steel ingots and potential casting safety risks. The present invention processes and analyzes the real-time detection data of the crystallizer liquid level during casting, can accurately judge the abnormal type of crystallizer liquid level fluctuation during casting, and guide the post operators to take corresponding disposal measures in time, which can significantly reduce the degradation loss of high-quality steel quality and the casting safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of crystallizer liquid level fluctuation data of Example 1 of the present invention;

[0018] Figure 2 This is a graphical diagram of the data after fast Fourier transformation in Example 1 of the present invention;

[0019] Figure 3 This is a schematic diagram of crystallizer liquid level fluctuation data in Example 2 of the present invention;

[0020] Figure 4 This is a graphical diagram of the data after fast Fourier transformation in Example 2 of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1-4 The present invention provides a technical solution: a method for accurately judging the type of abnormal fluctuation of the liquid level in a slab crystallizer, and the specific operation is as follows:

[0023] S1. During the slab casting process, when the crystallizer liquid level fluctuation is abnormal, about 0.5 hours of data is selected in the continuous casting machine data acquisition system, with the horizontal axis representing time and the vertical axis representing the crystallizer liquid level fluctuation value.

[0024] S2. Perform fast Fourier transformation on the selected data, that is, convert the signal value of the crystallizer liquid level fluctuation value from the time domain to the frequency domain, and set the output result to select a linear chart. At this time, the horizontal axis is frequency and the vertical axis is amplitude.

[0025] S3. When the calculation result graph is displayed as a "mountain" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is not changing the steel liquid flux in the crystallizer. When the calculation result graph is displayed as a "pointed" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is not changing the steel liquid flux in the crystallizer.

[0026] S4. For the abnormal crystallizer liquid level fluctuation whose essential type is not to change the molten steel flux in the crystallizer, timely treatment measures such as lowering the casting speed and reducing the amount of argon blowing on the stopper rod can be taken; for the abnormal crystallizer liquid level fluctuation whose essential type is to change the molten steel flux in the crystallizer, timely treatment measures such as feedforward control and increasing the amount of cooling water can be taken.

[0027] Embodiment 1:

[0028] During the casting process, the casting speed is 1.7m / min. When the mold liquid level fluctuation value exceeds ±5mm, an abnormality is observed. The data of about 0.5 hours is selected in the continuous casting machine data acquisition and analysis system. Figure 1 ; Perform fast Fourier transform on the above data, and the output result is displayed in the shape of a "mountain". Figure 2 ; It was judged that the type of molten steel flux in the crystallizer would not be changed. After reducing the casting speed to 1.5m / min, the crystallizer liquid level fluctuation value was reduced to ±4mm, and the ingot did not need to be downgraded, reducing the quality loss of the ingot.

[0029] Embodiment 2:

[0030] During the casting process, the casting speed is 1.5m / min, the cooling water volume is 1.2L / Kg, and when the crystallizer liquid level fluctuation value exceeds ±6mm, an abnormality is observed. The data of about 0.5 hours is selected in the continuous casting machine data acquisition and analysis system. Figure 3 ; Perform fast Fourier transform on the above data, and the output result is displayed as a "pointy" shape. Figure 4 ; It was judged that the type of molten steel flux in the crystallizer was changed. After the cooling water volume was increased to 1.3L / Kg, the crystallizer liquid level fluctuation value was reduced to ±4.5mm, and the ingot did not need to be downgraded, reducing the quality loss of the ingot.

[0031] To sum up, the method for accurately judging the abnormal type of slab crystallizer liquid level fluctuation is to accurately judge the abnormal type of crystallizer liquid level fluctuation during casting, take corresponding disposal measures in time, and greatly reduce the degradation loss of high-quality steel ingots and potential casting safety risks. The present invention processes and analyzes the real-time detection data of the crystallizer liquid level during casting, can accurately judge the abnormal type of crystallizer liquid level fluctuation during casting, and guide the post operators to take corresponding disposal measures in time, which can significantly reduce the quality degradation loss of high-quality steel and the casting safety risks.

[0032] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for accurately determining the type of abnormal fluctuation of the liquid level in a slab crystallizer, characterized in that: The specific operations are as follows: S1. During the slab casting process, when the crystallizer liquid level fluctuation is abnormal, about 0.5 hours of data is selected in the continuous casting machine data acquisition system, with the horizontal axis representing time and the vertical axis representing the crystallizer liquid level fluctuation value. S2. Perform fast Fourier transformation on the selected data, that is, convert the signal value of the crystallizer liquid level fluctuation value from the time domain to the frequency domain, and set the output result to select a linear chart. At this time, the horizontal axis is frequency and the vertical axis is amplitude. S3. When the calculation result graph is displayed as a "mountain" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is not changing the steel liquid flux in the crystallizer. When the calculation result graph is displayed as a "pointed" shape, it can be judged that the crystallizer liquid level fluctuation is abnormal and its essential type is changing the steel liquid flux in the crystallizer. S4. For the abnormal crystallizer liquid level fluctuation whose essential type is not to change the molten steel flux in the crystallizer, timely treatment measures such as lowering the casting speed and reducing the amount of argon blowing on the stopper rod can be taken; for the abnormal crystallizer liquid level fluctuation whose essential type is to change the molten steel flux in the crystallizer, timely treatment measures such as feedforward control and increasing the amount of cooling water can be taken.

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