JPH0619291B2 - Vibration monitoring equipment for rotating machinery - Google Patents

Description

Description: “Industrial field of use” The present invention relates to a vibration monitoring device for monitoring vibration of a rotating machine and detecting its abnormality.

“Prior Art” Conventionally, in order to continuously monitor the vibration state of a rotating body, a vibration monitoring method of detecting an amplitude value and a vibration increase rate of a vibration and outputting an alarm signal and a trip signal (Japanese Patent Publication No. 53-258).
86), a method of determining the vibration status by taking in the vibration information from different positions of the vibration monitoring target and obtaining the phase difference between the vibrations (Japanese Patent Laid-Open No. 55-22124), and the power of the detection signal. There is known a method (for example, Japanese Patent Laid-Open No. 58-193425) in which when the occurrence of subharmonic vibration is identified by analyzing the spectrum, the detection signal is bispectral analyzed to monitor the vibration.

In the method of "Problems to be solved by the invention", only the vibration amplitude and its increase rate are monitored, and it is impossible to monitor rolling bearings that normally generate vibrations of several kilohertz, and it is possible to estimate the cause by the vibration value. Was also impossible.

The method of (1) determines whether the vibration of the monitored object is approaching the resonance point by phase measurement, and is not suitable for bearings and the like that often generate vibrations that do not depend on the resonance point.

In the method (1), since a Fourier transform analyzer is used as a power spectrum analyzer, at the same time, only a few signals can be input at the same time, and there is a problem in accuracy in vibration monitoring in real time.

An object of the present invention is to provide a vibration monitoring device having a simple structure and capable of performing multipoint monitoring in real time.

[Means for Solving Problems] In the vibration monitoring device of the present invention, an acceleration sensor is attached to a bearing portion of a rotating body, acceleration signals are detected by these acceleration sensors, and signal processing is applied to the detected acceleration signals. Then, the acceleration average value, the acceleration peak value, and the velocity average value are derived. Each of these is converted into a digital amount and is taken into the arithmetic unit by the timer circuit in a constant time unit. The crest factor is obtained by dividing the captured acceleration peak value by the acceleration average value.

An alarm signal is output using the crest factor, velocity average value, and acceleration average value thus obtained as monitoring items, and the cause of the abnormality is estimated by identifying the magnitude of each vibration value in a matrix. Is possible.

"Embodiment" FIG. 1 shows an embodiment of the present invention. Accelerometer 1 ₁
1 to 1 _n are, for example, piezoelectric type acceleration sensors, which are attached to a rolling bearing portion (not shown) of the rotating machine. The signals detected by the acceleration sensors 1 ₁ to 1 _n are converted into voltage signals by the preamplifiers 2 ₁ to 2 _n , and the frequency components from 3 to 10 Hz to 1 kHz are further converted by the band pass filters 3 _{1 to} 3 _n. Is selected and integrator 4
₁ to 4 _n , converted into velocity signals by integrators 4 ₁ to 4 _n , and further averaged by averaging circuits 5 _{1 to} 5 _n .

On the other hand, the outputs of the pre-stage amplifiers 2 ₁ to 2 _n are bandpass filters 6 _{1 to} 6 _n.
1 kHz or less is removed and supplied to the averaging circuits 7 _{1 to} 7 _n for averaging. In addition, band wave device 6 ₁
Each output of the to 6 _n peak values each of which is detected by the peak detection circuit 8 ₁ to 8 _n.

Each velocity average value obtained from the averaging circuits 5 _{1 to} 5 _n is converted into a digital signal by the AD converters 9 _{1 to} 9 _n , and the averaging circuit 7
Each acceleration average value obtained from _{1 to} 7 _n is the AD converter 10 _1.
Is converted into a digital signal in to 10 _n, the peak detection circuit 8 ₁
The acceleration peak value than to 8 _n digital converter 11 ₁ to 1
It is converted into a digital signal at 1 _n . The velocity average value, the acceleration average value, and the acceleration peak value obtained as described above are input by the timer circuit built in the calculator 12 every unit time (for example, 7 seconds or more). Further, the ratio and the crest factor (peak value / average value) are calculated from the acceleration average value and the acceleration peak value among the input values.

Next, the velocity average value, the acceleration average value, and the crest factor are compared with preset values, and if they exceed the preset values, an alarm is output to the alarm device 13 and the respective input values are velocity averaged. The magnitudes of the values, the average acceleration value, and the threshold value of the crest factor are identified in a matrix to estimate the cause of the abnormality, and output to the display device 14 and the kanji printer 15.

In estimating the cause of the abnormality, the total vibration such as unbalance and load fluctuation appears as a change in speed value of 1 kHz or less, and the abnormality of the rolling bearing appears as a change in acceleration value of 1 kHz or more. Identify the frequency band of occurrence. As shown in FIG. 2, when the ball 21 makes a rolling motion in the race between the outer ring 22 and the inner ring 23, considering the vibration acceleration waveform of that motion, if the motion is normal, the amplitude is small as shown in FIG. If there is vibration, if there is no oil, it becomes a waveform without shock vibration close to noise with large amplitude as shown in Fig. 4, and if there is a scratch 25, shock vibration due to scratches in the normal waveform as shown in Fig. 5 26 will be on board. Bearing abnormalities are diagnosed by observing the characteristics of this waveform as changes in the average acceleration value and the crest factor.

"0" or "1" is output according to whether the speed detected by the averaging circuit 5 is lower or higher than the reference value, and the averaging circuit 7
"0" or "1" is output depending on whether the acceleration average value detected by is lower or higher than the reference value, and a 2-bit binary signal is output depending on whether the crest factor is in the high region, the medium region, or the low region. The diagnostic result storage section is read out in accordance with the output of these 4 bits in total, and the read diagnostic result is output to the printer. For example, when "0" or "0" low region is output, "there is a possibility that minute scratches will occur on the bearing, so be careful of future changes and carry out precise diagnosis."

Such a diagnosis result is stored in advance in the storage unit for each combination of the 4-bit outputs based on past experience. Further, the respective reference values and area values can be modified according to the device and its installation location.

In the above description, the detected acceleration signal is separated by the bandpass filter 3.6 and supplied to the integrator 4, the averaging circuit 7, and the peak detection circuit 8. However, the integrator and averaging are performed without band separation in this way. It may be supplied to the circuit and the peak detection circuit.

"Experimental Example 1" A drive motor (55 kW, 1500 revolutions / minute, 400) for a cylindrical extrusion plate type continuous centrifuge (manufactured by Tsukishima Kikai) shown in FIG.
Attaching a sensor 1 (Piezoelectric accelerometer, charge sensitivity 10PC / g ± 20%, resonance frequency 40kHz or more) to V Toshiba Toshiba Electric) to detect vibration acceleration signal and amplify it with pre-amplifier 2 and Signal processing was performed by the processing circuit shown in (1) and output to the Kanji printer 15. The results are shown in FIG.

In FIG. 7, the velocity average value curve 31 and the crest factor curve 33 do not change significantly, but only the acceleration average value curve 32 rises in the portion near the end of the recording, and there is a characteristic that the bearing runs out of oil. Recognize.

"Experimental Example 2" The same process as in Experimental Example 1 was carried out by attaching the sensor 1 to the drive side bearing portion of the centrifugal machine (Sharpless Super Decanter (rotational speed 3250 rpm, output 22 kW, manufactured by Tomoe Kogyo)) shown in FIG. The circuit causes the kanji printer 15 to output the result, and the result is shown in Fig. 9. In Fig. 9, only the velocity average value curve 34 changes, and the acceleration average value curve 35 has a reference value of 20 mm / s.
It can be seen that the crest factor curve 36 is very stable at 4 or less, and vibrations such as unbalance that are peculiar to the overall vibration occur. Further, according to FIG. 9, it is clear that the crest factor curve 36 is much more stable than changes in the velocity average value curve 34 and the acceleration average value curve 35, and only shock vibrations such as bearing scratches appear. Has been proven.

"Effects of the Invention" As described above, according to the present invention, the following effects can be obtained.

1) As a continuous monitoring item using a threshold value, in addition to the conventional velocity average value and acceleration average value, the acceleration peak value and the crest factor are incorporated to improve the accuracy of identifying the vibration generated in the bearing and reduce the oil shortage. Early detection of scratches is possible.

2) Even if an abnormality can be detected early in 1), it is not possible to deal with the problem only by outputting an alarm or the like as in the past.

However, according to the present invention, the various vibration characteristics obtained in 1) can be classified more than ever before, and the combination of each characteristic and its quantitative value makes it possible to estimate the cause of the abnormality and automatically output an instruction for treatment.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a multi-point continuous monitoring apparatus for a rotary machine according to the present invention, FIG. 2 is a diagram showing a rolling bearing, and FIG. 3 is a diagram showing an acceleration signal raw waveform in a normal state of the rolling bearing. FIG. 4 is a diagram showing a raw waveform of an acceleration signal when an oil shortage occurs, FIG. 5 is a diagram showing a raw waveform of an acceleration signal when a flaw is generated, and FIG. 6 is a diagram showing a cylindrical extrusion plate type continuous centrifuge, FIG. 7 shows the vibration monitoring output, FIG. 8 shows the centrifugal machine, and FIG. 9 shows the vibration monitoring output.

Claims (1)

[Claims] 1. An acceleration sensor mounted on a bearing of a rotating machine for detecting acceleration, a first averaging circuit for averaging acceleration signals detected by the acceleration sensor to detect an average acceleration value, and the acceleration described above. A peak detection circuit for detecting a peak value of a signal, an integrator for integrating the acceleration signal to output a speed signal, and a second averaging circuit for averaging the speed signals from the integrator to detect a speed average value. And a timer circuit that takes in the acceleration average value, the acceleration peak value, and the velocity average value in a constant time unit, and obtains a crest factor by dividing the taken acceleration peak value by the acceleration average value, and obtains the crest factor. A factor, an arithmetic unit that outputs an alarm signal with the average speed value and the average acceleration value as monitoring items, and an alarm device driven by the alarm signal are provided. Vibration monitoring device for rotating machinery.