JPS6154167B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an abnormality diagnosis device for rotating equipment that detects mechanical abnormalities in rotating equipment such as blowers, rolling mills, etc., such as unbalance of rotors, misalignment of rotating shafts, bends, flatness, and flaws in bearings. It is. Conventionally, this type of abnormality diagnosis involves detecting the mechanical vibration of rotating equipment and measuring its overall amplitude.
Two methods have been adopted: one is to read the vibration signal with a vibration meter and estimate the presence or absence of an abnormality based on its size, and the other is to perform a full-scale spectrum analysis of the vibration signal using a frequency spectrum analyzer and determine the presence or absence of an abnormality based on the analysis results. has been done. However, with the former method, only the total amplitude can be detected, so even if the total amplitude increases significantly, it is difficult to determine whether or not this is due to an increase in vibration due to an abnormality in the rotating equipment. Even if it was possible to determine that the increase in vibration was due to an abnormality in the rotating equipment, there was a fundamental problem in that it was impossible to determine at all what type of abnormality it was. In this regard, the latter method does not have the above-mentioned difficulties, but commonly used frequency spectrum analyzers are generally complicated to handle, have large dimensions, and are difficult to carry into sites where rotating equipment is installed. It is difficult to This problem can be resolved by bringing a data recorder to the site, recording the vibration data, then taking the recorded vibration data back and reproducing it, and analyzing the spectrum using the frequency spectrum analyzer mentioned above. , it takes a long time to obtain results, and it is difficult to accurately diagnose the presence or absence of an abnormality or the cause of an abnormality from a raw frequency spectrum. The process required skill and was impractical. The present invention has been made in view of this problem, and has been developed by secondary processing the vibration frequency spectrum so that it can be directly diagnosed on-site and the cause of the abnormality can be easily determined. The basic objective is to provide a practical and convenient abnormality diagnosis device for rotating equipment that can output the following information. Therefore, in the present invention, the vibration signal of the rotating equipment is passed through a predetermined band filter to remove unnecessary low-frequency signals and high-frequency signals, and then digitally converted, and this digital signal is subjected to digital calculation frequency spectrum analysis. Analyze the spectrum with a calculator. This spectrum analysis result is created by comparing the normal spectrum analysis result of the rotating equipment to be diagnosed with a reference frequency spectrum stored in memory in advance to create a difference spectrum, and the amplitude of this difference spectrum is determined by the reference frequency spectrum. Only when a predetermined reference value is exceeded, for example, the top 10 sets are selected from this difference spectrum, and the amplitudes of these 10 sets are arranged in order of magnitude and output. In addition,
This reference value is determined empirically from vibration analysis data of many rotating machines and is set to a constant value determined by the reference frequency spectrum of a normal rotating machine. These 10 sets of amplitudes are compared with the difference spectrum obtained by the next spectrum analysis and the average amplitude obtained as a result of the arithmetic mean of each amplitude of the previous difference spectrum, and each average amplitude is compared with the difference spectrum obtained by the next spectrum analysis. If the amplitude is equal to or greater than the amplitude, it is assumed that there is an abnormality cause corresponding to the frequency, and the top 10 sets of the frequency spectrum analysis value and the difference spectrum from the reference frequency spectrum are printed out and the abnormality of the rotating equipment to be diagnosed is determined. This is to warn you. Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments. In the drawings, 1 is an electrodynamic or piezoelectric type vibration detection device that is attached to a rotating device to be diagnosed for abnormality and extracts the vibration of the rotating device as an electrical signal, and 2 is an output signal of the vibration detection device 1. 3 is a high-frequency cutoff filter that cuts out high-frequency components unnecessary for abnormality diagnosis among the amplified vibration signals; 4 cuts off low-frequency components unnecessary for abnormality diagnosis; Together with the high-frequency cut-off filter 3, a low-frequency cut-off filter forms a band filter that passes only frequency components useful for abnormality diagnosis. 5 is an A/D converter that converts analog signals into digital signals for subsequent digital processing. 6 is a digital calculation type frequency spectrum analysis calculator for analyzing the frequency spectrum of the vibration signal converted into a digital signal; 7 is a reference frequency spectrum storage memory in which the frequency spectrum of the rotating equipment during normal operation is stored in advance; 8 is an arithmetic mean calculator that calculates the arithmetic mean of the frequency spectra calculated by the digital frequency spectrum analysis calculator 6 for the first time, second time, and so on (however, in the case of the first time, ), 9 is the frequency spectrum of the vibration of the rotating equipment calculated by the above-mentioned digital arithmetic frequency spectrum analysis calculator 6 and inputted via the arithmetic mean calculator 8, and the above-mentioned reference frequency. The amplitudes of the two are compared by matching each frequency with the reference frequency spectrum stored in the spectrum storage memory 7, and the amplitudes of the former are A(k ₁ ) and A.
(k ₂ ),...A(k _p ) is the latter reference amplitude As(k ₁ ),
A comparator that outputs this as a difference spectrum when it is larger than As(k ₂ ),..., As(k _p ) and exceeds a predetermined limit value for the reference amplitude; 10 is input from comparator 9. Amplitude difference signals ΔA(k ₁ ), ΔA(k ₂ ), ΔA(k ₃ ), ..., for each frequency k
a magnitude ranking determiner that compares the magnitude of ΔA(k _p ), ranks the top n sets, for example, 10 sets of difference signals among these difference signals in descending order of magnitude, and sequentially outputs the difference signals related to the determination; 11 is an abnormality determination circuit that determines the presence or absence of an abnormality from the output of the magnitude order determiner 10 and the output of the comparator 9, and displays the determination result as a signal;
Reference numeral 12 denotes a control circuit of a device that controls each operation timing of each circuit 6 to 11 after the A/D converter 5. As shown in Table 1, there are a wide variety of abnormalities in rotating equipment, and the frequencies generated by each abnormality range over a wide range. area cutoff filter 3
It is preferable that the cutoff band of the low frequency cutoff filter 4 be 2 to 5 KHz, and the cutoff band of the low frequency cutoff filter 4 be 0.1 to 10Hz. Note that these filters 3 and 4 may be replaced with filters of appropriate bands depending on the target model.

【table】

[Table] As shown above, by removing unnecessary vibration components on the high-frequency side and low-frequency side, it is possible to prevent vibration noise caused by other causes from entering, and also to use digital calculation type frequency spectrum analysis. During frequency spectrum analysis in the calculator 6, it is possible to prevent the occurrence of aliasing due to sampling of the data to be operated upon digital Fourier transform, so that large errors are not mixed into the analyzed values. The digital arithmetic frequency spectrum analysis calculator 6 uses a digital arithmetic circuit composed of LSI elements to perform FFT (Fast Fourier
A known method for performing (Transform) calculation can be used. The comparator 9 calculates the frequency calculated by the digital frequency spectrum analysis calculator 6.
Amplitude A(k ₁ ) for each k ₁ , k ₂ ..., k _i ..., k _p, ...,
A(k _i ),..., A(k _p ) and the reference amplitude A _s
(k ₁ ), ..., _As (ki), ..., _As (k _p ) difference amplitude ΔA (k ₁ ) (=A (k ₁ ) - _As (k ₁ )), ..., ΔA
(k _i )(=A(k _i )−A _S (k _i )),...,ΔA(k
_p ) (=A(k _p )−A _s (k _p )), and calculate the ratio r(k i ) of the difference amplitude ΔA(k _i ) and the reference amplitude A _s (k _{i )} .
(=ΔA(k _i )/A _s (k _i ) is larger than a predetermined limit value α(k _i ). This limit value α(k _i ) is By setting the limit value α(k i ) for each frequency k _i , accurate judgment may be made for each abnormality cause, but in some cases it may be set uniformly.This limit value α(k _i ) may be set appropriately depending on the type of rotating equipment, detection accuracy, cause of abnormality, etc. For example, α(k _i ) can be set in the range of 2 to 10. performs the following processing: (i) Prints out the amplitudes of, for example, 10 sets of difference spectra arranged in descending order by the magnitude order determiner 10. In this case, the printed contents include the frequency and its amplitude. The magnitude reference determiner 10 determines that if there is at least one amplitude of the difference spectrum that exceeds the reference range, the abnormality determination circuit 11 prints it out. (ii) Also, the magnitude reference determiner 10 When the amplitude of the difference spectrum exceeding the reference range is not detected at all, the abnormality determination circuit 11 prints out a message indicating that there is no abnormality, that is, it is normal. (iii) In the case of (i) above, The abnormality determination circuit 11 outputs a command signal to the control circuit 12, designates a frequency corresponding to the amplitude of the printed difference spectrum, and instructs the next reading calculation.According to this command signal, the digital calculation formula The frequency spectrum analysis calculator 6 continues the vibration of the rotating equipment and performs spectrum analysis, and the arithmetic mean calculator 8 calculates, for the specified frequency,
After calculating the arithmetic average of the previous amplitude and the current amplitude, the arithmetic averaged vibration and the corresponding amplitude of the reference frequency spectrum are compared in the comparator 9, and the amplitude difference is determined by the magnitude ranking determiner 10. , compare it with the previous corresponding amplitude difference. When the current amplitude difference is equal to or greater than the previous amplitude difference, the abnormality determination circuit 11 determines that the amplitude abnormality is not a coincidence, and prints out the presence of an amplitude abnormality at the frequency. On the other hand, when the current amplitude difference is smaller than the previous amplitude difference, the arithmetic averaging operation is performed at least once.
If the decreasing trend continues for more than 10 times, it is assumed that a sudden vibration component unrelated to any abnormality in the rotating equipment was accidentally detected at the time of the first vibration detection, and the diagnosis target is determined to have no abnormality. and print out the judgment details. If the abnormality determination circuit 11 determines that there is an abnormality, the calculated difference spectrum and the absolute value of the frequency spectrum are also printed out, so from the printed frequencies, for example, according to Table 1, The cause of the abnormality can be quickly determined. As is clear from the above description, the present invention uses a vibration detection device to extract vibrations of rotating equipment as electrical signals, and uses a band filter to remove low-frequency and high-frequency vibration components that are unnecessary for abnormality determination. The A/D converted signal is then subjected to spectrum analysis using a digital frequency spectrum analysis calculator, and the analysis results are compared with the reference frequency spectrum of the rotating equipment during normal operation using a comparator. If the difference spectrum of the frequency spectrum that can be considered as , that is, the frequency spectrum obtained by analyzing the normal reference frequency spectrum, exceeds a predetermined limit value, output the difference vibration and input it to the magnitude standard judger. Then, the top n groups are selected and input to the abnormality judgment circuit, and the abnormality judgment circuit calculates the arithmetic average of the next and subsequent amplitudes for frequencies that can be considered abnormal, and calculates the arithmetic averaged amplitude and the reference amplitude. The present invention provides an abnormality diagnosing device for a rotating equipment, which compares the difference amplitude between the two and the previous difference amplitude, and determines whether or not the estimated abnormality has occurred. Therefore, according to the present invention, it is possible to extract the signal components necessary for diagnosing abnormalities in rotating equipment, and moreover, it is possible to reliably and accurately detect the frequency at which the abnormality occurs. Not only that, but also the cause of the abnormality can be ascertained, and since this device is small enough to be brought into the field, it is possible to immediately diagnose the presence or absence of an abnormality on-site, and it is also easy to use by experienced technicians. It is possible to provide a practical abnormality diagnosis device for rotating equipment that allows the user to at least engage in diagnostic work. Further, according to the present invention, even if there is a difference amplitude exceeding a limit value in one calculation of the difference spectrum, it is not immediately determined to be an abnormality, but the abnormality is determined to exist from the next time onwards by considering the frequency spectrum from the next time onward. Since it is possible to determine that there is an abnormality only when
Single or sudden disturbance data can be reliably excluded, and the reliability of abnormality determination can be greatly improved.

[Brief explanation of the drawing]

The drawing is a block circuit diagram of an abnormality diagnosis device according to an embodiment of the present invention. 1...Vibration detection device, 3...High frequency cutoff filter, 4...Low frequency cutoff filter, 5...A/
D converter, 6... Digital calculation type frequency spectrum analysis calculator, 7... Reference frequency spectrum storage memory 8... Arithmetic mean calculator, 9... Comparator,
10... Size order determiner, 11... Abnormality determination circuit.

Claims (1)

[Scope of Claims] 1. Vibration detection means for detecting vibrations of rotating equipment as electrical signals; Among the electrical signals output from the vibration detection means, only signals in a passband set corresponding to the reference vibration of the rotating equipment are detected. A band pass filter, an analog-to-digital converter that converts the electrical signal passed through the band filter into a digital signal, a digital frequency spectrum analysis calculator that calculates a frequency spectrum from the digital signal, and a normal state of the rotating equipment. a reference frequency spectrum storage memory in which a frequency spectrum is stored in advance; a means for creating a difference spectrum between the calculated frequency spectrum and the reference frequency spectrum; and a means for creating a difference spectrum between the calculated frequency spectrum and the reference frequency spectrum; Comparing means for comparing with a preset limit value and sequentially outputting amplitudes greater than the limit value; and determining the magnitude of the amplitudes output by the above comparing means, and determining the top n groups (where n is a positive integer). and a magnitude order discriminating means that outputs the amplitudes in descending order of magnitude, and a magnitude order discriminating means that outputs the amplitudes of n sets of amplitudes only when a significant difference spectrum occurs. an arithmetic mean calculation means that reads the analysis results and calculates the arithmetic mean with the next frequency spectrum; An abnormality diagnosing device for a rotating equipment, comprising an abnormality determining means for comparing the average amplitude value obtained by the first amplitude value and determining that an abnormality exists for the frequency when the average amplitude value is equal to or greater than the initial amplitude value.