JP2015009261A - Method and device for detecting chattering of cold rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for detecting chattering of a cold rolling mill capable of detecting precisely occurrence of chattering in the cold rolling mill.SOLUTION: Vibration of a cold rolling mill is measured, and measured vibration is subjected to frequency analysis. Then, it is determined that chattering occurs when the acquired vibration intensity is stronger than an intensity threshold set beforehand, and at that time, each intensity threshold is set in each frequency band.

Description

  The present invention relates to a method and apparatus for detecting chattering caused by vibration of a cold rolling mill.

  Chattering that occurs when cold rolling a steel sheet is a vibration phenomenon of a cold rolling mill, and is known to occur at a plurality of frequencies (frequency) over a frequency (frequency) of about several tens to 600 Hz. (For example, refer nonpatent literature 1).

  In other words, the cause of chattering is the resonance between the natural vibration of the cold rolling mill and the vibration of the rotating system such as the rolling roll, the slip phenomenon between the rolling roll and the steel plate, the cold due to flaking of the roll chock, etc. The vibration of the rolling mill is considered, and it is said that it occurs at different frequencies depending on the cause of each occurrence.

  The larger the vibration intensity (amplitude or vibration acceleration) of chattering, the greater the influence on the plate thickness of the steel plate, thereby causing the plate thickness variation.

  As a method for directly detecting the occurrence of such chattering, a method of measuring the sheet thickness (sheet thickness fluctuation) of the steel sheet immediately after cold rolling and detecting it based on the measurement result can be considered. Therefore, it is difficult to detect the occurrence of chattering with a thickness gauge provided on the cold rolling mill exit side. Therefore, a method for indirectly detecting the occurrence of chattering must be taken.

  Therefore, as a method of indirectly detecting the occurrence of chattering, a method of measuring the vibration of the cold rolling mill is often used.

  For example, in Patent Document 1, a vibration sensor is installed on the upper part of the housing of the cold rolling mill, the vibration of the cold rolling mill is measured, the measured vibration waveform is frequency-converted (frequency analysis), A method of detecting the occurrence of chattering by comparison with an intensity threshold is performed.

  Incidentally, FIG. 1 shows a specific example of the detection method described in Patent Document 1. FIG. 1A shows the measured vibration waveform, and FIG. 1B shows the result of frequency analysis (here, Fast Fourier Transform FFT).

JP 2010-234422 A JP 2001-25812 A

Theory and practice of sheet rolling (revised version) Japan Iron and Steel Institute 2010

  However, the method described in Patent Document 1 has the following problems.

  That is, in the method described in Patent Document 1, as shown in FIG. 1, the occurrence of chattering is detected using one intensity threshold for the vibration intensity (generated intensity) obtained by frequency analysis. ing.

  On the other hand, when chattering actually occurs, it does not always occur when the vibration intensity (intensity threshold) is equal to or higher than a certain level. . For example, as shown in FIG. 2B, when the generation frequency is 124 Hz and the generation intensity is 0.036, chattering occurs, whereas as shown in FIG. Is 76 Hz and the generated intensity is 0.05, chattering does not occur.

  For example, FIG. 3 shows the vibration intensity after frequency analysis in the case of vibration due to chock flaking (occurrence of chattering), but it occurs in a lower frequency region than the vibration intensity due to chock flaking. The intensity of vibration due to the rotating system is higher. That is, chattering does not always show the highest intensity.

  Therefore, in the method of detecting the occurrence of chattering using one intensity threshold as in the method described in Patent Document 1, chattering is excessively detected (false detection), or conversely, the chattering to be detected is overlooked. There is a possibility.

  The present invention has been made in view of the above circumstances, and provides a cold rolling mill chattering detection method and apparatus capable of accurately detecting the occurrence of chattering in a cold rolling mill. It is the purpose.

  In order to solve the above problems, the present invention has the following features.

  [1] A method of detecting chattering of a cold rolling mill, measuring vibrations of the cold rolling mill, performing frequency analysis on the measured vibrations, and the obtained vibration intensity being greater than a preset strength threshold The chattering detection method for a cold rolling mill is characterized in that chattering is determined to occur and the intensity threshold is set for each frequency band.

  [2] The chattering detection method for a cold rolling mill according to [1], wherein the frequency band and the strength threshold can be changed according to a steel type, a width, and a plate thickness of a steel strip to be rolled.

  [3] The chattering detection method for a cold rolling mill according to [1] or [2], wherein when the vibration of the cold rolling mill is measured, the vertical vibration of the mill housing is measured. .

  [4] A device for detecting chattering of a cold rolling mill, a vibration measuring device for measuring the vibration of the cold rolling mill, a frequency analyzing device for frequency analysis of the measured vibration, and the obtained vibration intensity A chattering detection device for a cold rolling mill, comprising: an occurrence determination device that determines that chattering has occurred when greater than a preset strength threshold, wherein the strength threshold is set for each frequency band.

  [5] The chattering detection apparatus for a cold rolling mill according to [4], wherein the frequency band and the strength threshold value can be changed according to a steel type, a width, and a plate thickness of a steel band to be rolled.

  [6] The chattering detection device for a cold rolling mill according to [4] or [5], wherein the vibration measurement device measures vibration in a vertical direction of the mill housing.

  In the present invention, the occurrence of chattering in a cold rolling mill can be accurately detected.

It is a figure which shows a prior art (patent document 1). It is the figure which illustrated the relationship between a frequency analysis result and chattering generation | occurrence | production. It is a figure which shows the frequency analysis result at the time of chock flaking generation | occurrence | production. It is a figure which shows the frequency analysis result and intensity | strength threshold value in one Embodiment of this invention. It is a figure which shows the system configuration | structure in one Embodiment of this invention.

  In the present invention, the vibration of the cold rolling mill is measured, the measured vibration is subjected to frequency analysis, and it is determined that chattering has occurred when the obtained vibration intensity is greater than a preset intensity threshold. At that time, the intensity threshold is set for each frequency band.

  Hereinafter, an embodiment of the present invention will be described.

  In this case, the steel strip of the steel grade SPCEU material is rolled at an inlet side plate thickness of 3.5 mm, an outlet plate thickness of 0.75 mm, and a rolling speed of 1000 mpm by a four-stage cold rolling mill having a work roll diameter of 600 mm and a backup roll diameter of 1490 mm. did. At that time, a vibration meter was installed on the upper part of the mill housing, and the vertical vibration of the cold rolling mill was measured.

  FIG. 4 is a diagram illustrating a result of frequency analysis of a vibration waveform obtained by the vibrometer using a frequency analysis device, and a preset intensity threshold.

  As shown in FIG. 4, in this embodiment, the frequency region includes three frequency bands: a first frequency band (0 to 100 Hz), a second frequency band (100 to 250 Hz), and a third frequency band (250 to 750 Hz). Intensity thresholds are set for each frequency band.

  Here, when setting the intensity threshold value for each frequency band, as described above, in consideration of the fact that chattering is unlikely to occur even in the low frequency region even if the vibration intensity is high, the low frequency band (first frequency) The intensity threshold is set to be smaller in order from the band) toward the high frequency band (third frequency band).

  The frequency band and strength threshold can be set based on the past operation results and experimental results. The frequency band and strength threshold are changed according to the steel type and dimensions (width, thickness) of the steel strip to be rolled. It is preferable to be able to do so.

  FIG. 5 shows a system configuration when setting the frequency band and the strength threshold according to the steel type and dimensions of the steel band to be rolled.

  In the case of FIG. 5, the frequency band and the intensity threshold are set by O / C (online computer), and the measured values and the frequency analysis result of the vibration meter are collated through P / C (process computer). ing.

  Note that the frequency band and the intensity threshold may be set by P / C (process computer).

  As an example of the present invention, using a four-stage cold rolling mill with a work roll diameter of 600 mm and a backup roll diameter of 1490 mm, a steel strip of a steel grade SPCEU material has an inlet side thickness of 3.5 mm, an outgoing side thickness of 0.75 mm, and rolling. Rolling was performed at a speed of 1000 mpm, and chattering was detected.

  At that time, as an example of the present invention, chattering was detected based on the above-described embodiment of the present invention. On the other hand, as a comparative example, the occurrence of chattering was detected using the method described in Patent Document 1 described above.

  And the steel strip after rolling was rewound, it was investigated whether chattering actually generate | occur | produced, and it matched with each detection result.

  As a result, in the comparative example, it is determined that chattering has actually occurred but there is no evidence of chattering, or that chattering has actually occurred but chattering has not occurred. There were quite a few false positives.

  On the other hand, in the present invention example, there was no erroneous detection as described above, and the occurrence of chattering could be accurately detected.

Claims (6)

  A method for detecting chattering of a cold rolling mill, measuring vibrations of the cold rolling mill, performing frequency analysis of the measured vibrations, and chattering when the obtained vibration strength is greater than a preset strength threshold A method of detecting chattering of a cold rolling mill, wherein the intensity threshold is set for each frequency band.   The chattering detection method for a cold rolling mill according to claim 1, wherein the frequency band and the strength threshold value can be changed according to a steel type, a width, and a sheet thickness of a steel strip to be rolled.   3. The chattering detection method for a cold rolling mill according to claim 1, wherein when the vibration of the cold rolling mill is measured, the vertical vibration of the mill housing is measured.   A device for detecting chattering of a cold rolling mill, a vibration measuring device for measuring the vibration of the cold rolling mill, a frequency analyzing device for frequency analysis of the measured vibration, and the obtained vibration intensity are preset. A chattering detection device for a cold rolling mill, comprising: an occurrence determination device that determines that chattering has occurred when greater than an intensity threshold, and wherein the intensity threshold is set for each frequency band.   The chattering detection device for a cold rolling mill according to claim 4, wherein the frequency band and the strength threshold value can be changed according to a steel type, a width, and a plate thickness of a steel band to be rolled.   The chattering detection device for a cold rolling mill according to claim 4 or 5, wherein the vibration measuring device measures vibration in a vertical direction of the mill housing.

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