JPS59212512A - Watching for plain bearing - Google Patents

Abstract

PURPOSE:To early detect the damage of a bearing by comparing the effective value which is obtained by envelope processing the acoustic emission detected by a sound detection element and the effective value of the component in a prescribed frequency range. CONSTITUTION:The AE signal supplied from an acoustic emission (AE) sensor 3 installed in a plain bearing 1 is amplified by a preamplifier 4 and a main amplifier 5 and then envelope-processed by an envelope-processing circuit 6 and sent into an effective value detecting circuit 7a to detect an effective value S0. Further, this signal is sent into an effective-value detecting circuit 7b through a band-pass filter 8, and the effective value SF in a prescribed frequency range is detected. The both effective values S0 and SF are sent into an arithmetic circuit 9, and the ratio is obtained and displayed on a display apparatus 10. The advance state of the bearing is watched by surveying this ratio.

Description

[Detailed description of the invention] The present invention relates to a method for monitoring plain bearings.

Sliding bearings are common bearings used in rotating parts of various machines, but f) Although through the NJ oil film, +i
Since the nt receiving metal and the journal come into direct surface contact, damage is likely to occur. Various methods such as temperature method, pressure method, vibration method, DC resistance method, etc. have been used in the past to monitor the condition of the bearing.

The temperature method measures the temperature of the bearing metal, and when an abnormality occurs in the bearing metal, the frictional resistance between the bearing metal and the journal increases, so the temperature of the bearing metal increases. It was used. However, with this method, by the time the temperature rise of the lll1lI receiving metal is measured, damage to the +ll+ receiving metal has already progressed to a considerable extent, and early detection is not possible.

The pressure method is a method of measuring the pressure of a single oil film between the bearing metal and the journal, and is intended to detect any abnormalities in the bearing based on changes in this pressure, but the pressure of the oil film changes depending on the load, etc. However, it is not easy to measure the pressure of Ushidako's glaze! There is point iI.

The vibration method takes advantage of the fact that when damage occurs to a bearing, the journal no longer rotates smoothly and vibrations are generated, but like the temperature method, by the time vibration occurs, the damage has already progressed to a considerable extent. Therefore, early detection is still impossible.

In addition, the DC resistance method applies a DC current between the bearing metal and the journal and measures the resistance value, but it requires complete insulation between the bearing metal and the journal, which makes it impractical. Therefore, it has been difficult to detect damage to sliding bearings early and to monitor and judge its progress, and by the time an abnormality is discovered, it is already too late to cause a serious failure or accident. I had come to see it.

The present invention was made in view of these circumstances, and
Acoustic emissions of the sliding bearing are detected by an acoustic detection element, this detection signal is subjected to envelope processing by an envelope processing circuit, and the effective value of the envelope processed signal and a predetermined value extracted from the envelope processed signal are calculated. The present invention is characterized in that the ratio between the frequency band component and the effective value is determined, and the state of the sliding bearing is determined based on the magnitude of this ratio. Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a block diagram showing an example of an apparatus used to carry out the method of the present invention. In the figure, reference numeral 1 denotes a beveled bearing, in which a cylindrical bearing metal 1a is fitted and fixed in a cylindrical opening, and a journal 2, which is a rotating member, is fitted into this bearing metal 1a. When this journal 2 rotates and slides within the bearing metal 2, acoustic emissions (hereinafter referred to as A) are emitted.
An elastic wave called E (abbreviated as E) is generated. If there is no damage to the bearing metal 1a, the AE will be low, but the bearing metal 1a
If damage occurs, AE will be placed rapidly.

By measuring this AE, it becomes possible to judge whether deformation or failure of the solid has actually occurred and is progressing.

3 in the figure is an AE sensor, which is used to detect the elastic waves generated by the AE phenomenon described above, and uses an appropriate acoustic detection element such as a PZT (lead zirconate/lead titanate) ceramic piezoelectric element. .

After the AE multiplied signal detected by the AE sensor 3 is amplified by the preamplifier 4 and main amplifier 5, it is subjected to envelope processing in the envelope processing (detection) circuit 6 as shown in FIG. Figure 2 (a) shows the main amplifier 5 which amplifies the signal by AE times.
, that is, the waveform of the spacing signal sent to the envelope processing circuit 6, and (b) is the output waveform 1 after envelope processing by the envelope processing circuit 6. The signal after the envelope processing is applied to the effective value detection circuit 7a, and the effective value S of the entire AE signal after the envelope processing is obtained. is detected, while the bandpass filter 8
It is also given to

Bandpass filter 8 is 600 kHz to 900 kHz
The frequency band of
This is because it was concluded that an AE multiplied signal in the range of 00 kHz to 900 kHz is generated.

The signal that has passed through the bandpass filter 8 is given to the effective value detection circuit 7b, and 600 of the AE multiplied signal after envelope processing is applied to the effective value detection circuit 7b.
The effective value etc. of the band from kHz to 900 kHz is detected.

In this way, the effective value So of all AE signals after envelope processing detected by both effective value detection circuits 7a and 7b, respectively.
The effective value SF in the frequency band of 600 kHz to 900 kHz is given to the arithmetic circuit 9, and the ratio M=S,
/S.

is calculated and displayed on an appropriate display device 10.

Next, an example of actual monitoring and measurement when the method of the present invention is implemented with the above configuration will be described.

The table below shows the S0. The values of SF and M are tabulated.

Further, FIG. 3 is a graph in which the M value in the above table is shown as a black circle, and the σ1j determination result by the conventional vibration method, which was measured at the same time for comparison, is shown as a white circle.

As is clear from the table and FIG. 3, as the degree of damage to the sliding bearing increases, the value of M also increases, making it possible to quantitatively judge the degree of damage. In addition, with the conventional vibration method, the measured value is approximately constant and early detection of damage is impossible, whereas with the method of the present invention, the above-mentioned device is installed on the sliding bearing, and the AE of the sliding bearing is By measuring this, it is possible to detect the occurrence of damage at an early stage.

As detailed above, the present invention detects the acoustic emission of a sliding bearing using an acoustic element, and the ratio of the effective value of this detection signal after envelope processing to the effective value of a component in a predetermined frequency band after envelope processing. Yoshizube! Since the condition of the bearing is determined, if the sliding bearing is monitored using the method of the present invention, it will be possible to detect abnormalities at an early stage, and it will also be possible to quantitatively evaluate the degree of damage. The present invention has excellent effects on monitoring the condition of sliding bearings.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an apparatus for implementing the method of the present invention, and FIG. 2 is a graph showing the input waveform and output waveform of the envelope processing circuit. ! FIG. 3 is a graph showing the results of measuring damage to sliding bearings according to the method of the present invention and the conventional method. 1... Sliding bearing 3... Acoustic detection element 6... Envelope processing circuit 7a, 7b... Effective value detection circuit 8...
・Band pass filter 9... Performance 8 circuit patent applicant Sumitomo Kintoki Kogyo Co., Ltd. Representative Patent Attorney Yokio Kono No. 1 Fig. 2 Fig. 3

Claims (1)

[Claims] 】, Acoustic emission of the vesi bearing is detected by the acoustic detection element, this detection signal is envelope-processed by the envelope processing circuit, and the effective value of the envelope-processed signal is calculated.
A method for observing a sliding bearing, characterized in that the ratio between the effective value and the component of a predetermined frequency band extracted from an envelope-processed signal is determined, and the state of the sliding tilt bearing is determined based on the magnitude of this ratio.