JPH0312533A - Method for estimating remaining life of bearing - Google Patents

Abstract

PURPOSE:To obtain an accurate estimation result by calculating a vibration acceleration increase rate by the rest life estimating method for the bearing in consideration of an event of 'respiration area'. CONSTITUTION:A vibration acceleration sensor 10 is fixed to a circuit for estimation and a voltage signal which is proportional to its vibration acceleration intensity is obtained, amplified by a preamplifier 12, and sent out to a repeater, so that a microcomputer 16 performs arithmetic control eventually. When the current found vibration acceleration increase rate decreases below the last rate by more than a specific rate, it is considered that the life of the bearing enters the 'respiration area' and the subsequent calculation of the rest life is interrupted; when the maximum increase rate for the past is obtained, it is considered that the life exists from the 'recipiration area' and a curve is approximated based upon the values obtained by shifting the current increase rate and a specific number of increase rates before the life enters the 'area' by the period DELTAt of the 'area' ahead, thereby restarting the calculation of the rest life. Consequently, the accurate estimation result is obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for estimating the remaining life of a bearing built into a three-rotating device, and more specifically, the present invention relates to a method for estimating the remaining life of a bearing incorporated in a three-rotating device, and more specifically, the present invention relates to a method for estimating the remaining life of a bearing built into a three-rotating device, and more specifically, Related to a method for estimating the remaining life of a bearing for calculating its life [Prior art] Various attempts have been made to predict the failure of a bearing based on the change over time in the vibration acceleration intensity of a rotating device that incorporates the bearing. The technique described in Publication No. 59-81531 can be mentioned.

This involves fixing a piezoelectric element-type vibration acceleration sensor to each rotating device, time-sharing the signal output from the sensor using a scanning device, and sending it to a frequency analyzer. Detects the vibration acceleration intensity within the range. If the average value of the vibration acceleration intensity within the range is 6 times or more than the preset initial value, it is determined that the area has entered the "abnormal region" and the bearing is stopped before it is destroyed. This is a warning to replace it. According to this, it is certainly possible to predict bearing failure, but it is not possible to predict the remaining life of the bearing, such as "how many hours left until failure occurs," making it difficult to plan the operation and maintenance of equipment. could not. Therefore, based on the above-mentioned destructive predictive maintenance method.

A method for estimating the remaining life of a bearing is being attempted, which calculates how many hours it will take for the bearing to fail.

To do this, first, the vibration acceleration intensity detected at regular intervals by the above method is divided by the initial value, and the quotient is determined as the "current vibration acceleration increase magnification".

Next, this increase magnification and the previous 19i11! ! A point in time when a measured value 6 times or more of the initial value (hereinafter referred to as "abnormal threshold") is obtained by curve approximation based on the increase rate at a fixed point (i.e., the increase rate at 20 points in total) tx is intended to calculate how many hours after the current measurement time for each measurement time. According to this, the data on which the calculation is based is updated one by one each time the measurement time point advances one by one, so that the remaining life of the bearing, which changes from moment to moment, can be calculated more accurately.

[Problem to be solved by the invention]

The above remaining life estimation method draws a curve based on a certain number of data (7JO multiplication factor), and the abnormal threshold (
Since this method calculates the time required to reach an increase factor of 6 or higher, accurate estimation cannot be made unless the increase factor at each measurement point constantly increases over time. . However, the increase rate does not generally increase from the initial stage to destruction, but as shown in Figure 5, the so-called ``breathing zone'' where the increase rate once decreases is repeatedly inserted. It shows a tendency to grow while looking at something and reach its final destruction.
Therefore, if you do not calculate the time required to reach the abnormal threshold value simply based on the increase rate at each fixed measurement time point as in the conventional method, the increase rate in the above-mentioned "respiratory range" can also be calculated as it is by 1 of the data. As a result, the prediction accuracy becomes extremely low, and in some cases, it becomes impossible to calculate.

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional methods.

The object of the present invention is to provide a method that makes it possible to accurately estimate the remaining life of a bearing while targeting the vibration acceleration increase factor that grows while inserting the "breathing region".

[Means to solve problems]

In order to achieve the above object, the present invention calculates the current vibration acceleration increase magnification by dividing the vibration acceleration intensity at each measurement point at arbitrary intervals detected from a rotating device incorporating a bearing by a predetermined initial value. Calculate.

The time required to obtain a vibration acceleration increase factor of a predetermined value or higher by approximating a curve based on the current vibration acceleration increase factor and the vibration acceleration increase factor obtained at a predetermined number of previous points in the past at each measurement point. In the method of estimating the remaining life of a bearing, which is calculated for each bearing, if the current vibration acceleration increase rate decreases by more than a predetermined ratio with respect to the previous vibration acceleration increase rate, it is considered to have entered the "breathing range". The calculation of the remaining life after that point will be discontinued, and once the highest ever vibration acceleration increase rate is obtained, it will be assumed that the "breathing range" has been exited, and the vibration acceleration increase rate at that point and The calculation of the remaining life of the bearing is restarted by approximating the curve based on the vibration acceleration increase factor at a predetermined number of points before entering the "breathing region" and shifting it to a point in time △t minutes after the "breathing region". It was configured as follows.

[Effect]

With the above configuration, when estimating the remaining life of the bearing, the increase magnification obtained in the "breathing region" can be divided by tJl, and accurate estimation results can be obtained.

〔Example〕

Examples of the present invention will be described below.

As shown in FIG. 1, the method for estimating the remaining life of a bearing according to the present invention is as follows: First, a piezoelectric element-type vibration acceleration sensor IO serving as a vibration acceleration detection end is fixed to a rotating device (not shown) containing a bearing, and the vibration It starts by comparing the acceleration to the horizontal. That is, if there are scratches on the balls (or rollers) of the bearing or the inner or outer rings that contact them, periodic vibrations occur as the shaft rotates. Since the sensor outputs a voltage signal proportional to the vibration acceleration intensity, by monitoring the signal, it is possible to ascertain the presence or absence of scratches and the extent of the scratches. The vibration acceleration sensor is fixed vertically to the bearing part of the one-rotation device with a screw or adhesive. Note that since the sensor itself is well known, further explanation will be omitted.

The voltage signal is amplified by the preamplifier 12 and then sent to the repeater 14. A plurality of imaging acceleration detection terminals are connected to the repeater, and the built-in scanning (time division) function allows switching to each imaging acceleration detection terminal sequentially, so 4I in one repeater! The device can process up to 32 vibration acceleration detection points. Naka Naka 2; has a built-in vibration accelerometer.

In a vibration accelerometer, the input voltage signal is first converted to an absolute scale of G (-9.8m/SJ, which is the unit of vibration acceleration.Next, the frequency band to be analyzed by the filter built into the vibration accelerometer is The range of is determined.

That is, the vibration accelerometer has five bypass filters that determine the lower limit of the analysis range and five low-pass filters that determine the upper limit.
The internal organs of each type are familiar. The size of each filter is as follows.

(low pass 50k lI z 20kHz
10 k If z 1 k If z 500
k If z filter) (Bypass 1 k It z 500 II z
10il z 5 Hz I It z filter) The measurement range of vibration acceleration is determined by combining one type of each of the various sizes of the above-mentioned low-pass filter and bypass filter. The combination of filters is commanded and controlled by a microcomputer 16 for the arithmetic control jTJ. The vibration acceleration is decomposed into a high frequency component (1 kllZ to 50 kttz) and a low frequency component (I Hz to 1 kHz) by the filter. In addition to bearing imaging, the low-frequency component contains abnormal vibrations of the machine (for example, vibrations caused by backlash, imbalance, etc. between two machines), and is therefore used for diagnosing abnormal vibrations of the machine as described later. On the other hand, high-frequency components including an ultrasonic range of 16 klIz or higher, which is less affected by abnormal vibrations of a single machine, are used for predictive diagnosis of bearing failure. The low-frequency components are sent as they are to the next-stage frequency analyzer 18, but the high-frequency components are half-wave rectified and then subjected to envelope processing that connects the peak values, and are converted into demodulated waves before being sent to the frequency analyzer 1.
Sent on 8th.

In the frequency analyzer 18, only the vibration acceleration intensity of a specific frequency is extracted from the high frequency components and monitored. This specific frequency is a frequency corresponding to each of the balls (rollers), inner ring, and outer ring that constitute the above-mentioned bearing. That is, the bearing is composed of an outer ring fixed to a bearing box, balls (rollers), an inner ring fixed to a rotating shaft, and a cage. If any of the parts that make up this bearing are damaged, the rotation of the shaft causes the inner ring, balls, and outer ring to repeatedly collide, so even small scratches gradually grow and lead to destruction. Therefore, for each part that makes up this bearing,
By determining the mechanical collision frequency using the following formula, which is a function of the rotational speed and rotational diameter of the shaft, and monitoring the increasing tendency of the vibration acceleration intensity at this frequency, it is possible to predict the fracture location and degree of fracture. It can be done.

Outer ring monitoring frequency: ZXfc re = fr/2 ・(1-d/D ・coscr)
Inner ring monitoring frequency: ZX fi ri = fr - (c Ball (roller) monitoring frequency: fh fb - fr/2 ・D/d (1-dIl/D"co
sα) d: Diameter of ball (roller) (ms) D: Diameter of Binochi circle (ms) α: Contact angle of ball (roller) (deg) Z: Number of balls (roller) (pieces) fr: Rotation of shaft Frequency (H2) rc: Rotation period of cage (Hz) ri: Rotation frequency of shaft and cage (H2) rb: Rotation frequency of ball (roller) (Hz) The components of each frequency found above are 1 is converted into a digital signal via the CP/IB interface of the frequency analyzer 18, and the vibration acceleration intensity is determined. In addition, instead of monitoring the specific frequency of each component of the bearing as described above, it is also possible to predict the failure of the entire bearing by using the digitalized average value of the frequencies included in the high-frequency components. It is possible. Further, in parallel with monitoring each constituent part of the bearing, prediction of failure of the entire bearing may be performed.

Next, extract the vibration acceleration intensity obtained as described above at each arbitrary time, divide it by a predetermined initial value, and measure the current vibration acceleration increase magnification (hereinafter simply referred to as "increase magnification"). do. If this increase rate is 5 or more, we will assume that it has entered the caution range and prepare replacement parts, and if it is 6 or more, it can be destroyed at any time. Assuming that it has entered an abnormal zone, we will replace the damaged part before actual destruction occurs. This makes it possible to avoid damage caused by sudden destruction. Note that the initial value refers to the vibration acceleration intensity of each predetermined frequency at the time of introducing a rotating device or replacing a bearing (that is, when the bearing is in an undamaged state). or,
It was determined based on past experimental rules that an increase rate of 6 or more would cause the situation to enter the abnormal region.

As described above, the predictive maintenance method according to the present application is based on the increase factor that indicates how many times the vibration frequency specific to the component parts of the bearing has increased from the initial value that was "normal". This method is based on the relative criteria method that determines the occurrence of damage and identifies the location where the failure occurred.

Since the relative criterion method requires frequency analysis results of bearings under normal conditions, it cannot be applied to rotating equipment for which there is no frequency analysis data under normal conditions. Therefore, for such rotating equipment, until the next intersection +6 when the initial value is obtained, +5
Diagnosis is made using the absolute criteria method defined in the 0 standard. The table below shows the condition diagnostic thresholds of the ISO standard absolute criteria method.

(ISO Standard 2372-1984) The wooden table means that in general rotating equipment, if the vibration speed exceeds 4 am/s, some kind of deterioration is progressing. In the case of this embodiment, the effective value of the vibration acceleration is calculated from the vibration acceleration including vibrations in the ultrasonic range of 16 k lI z or more using the following formula.

Vrms = 9600G/(2/7πf) Here, V is the actual value of vibration velocity (mm/s), G is vibration acceleration expressed as a multiplier for gravitational acceleration, and r is frequency (II
z).

According to the method described above, predictive maintenance of bearings is possible, but it is not possible to predict how many hours it will take for the bearings to break down. Therefore, a method for estimating the remaining life of a bearing based on the above-mentioned destructive predictive maintenance method will be explained below.

In the bearing remaining life estimation method according to the present application, first, when the current increase magnification obtained as described above becomes 3 or more, the interval between the previous measurement points is shortened. For example, reduce the interval from once a day to once every 30 minutes. Then, the remaining life is estimated by approximating one curve using the current increase rate and the increase rate at 19 previous points in the past (that is, the increase rate at 5 total 20 points) as data. That is, the increasing tendency of the increase magnification is approximated by an exponential function, the constant of the exponential function is determined moment by moment using the least squares method, and the remaining time until the expected increase curve of the 1 magnification reaches a vibration acceleration 6 times the initial value is calculated backwards. It is. in particular,
Calculate the remaining life time using the following formula.

A・e−”=6 A: Tangent of the curve B: Around 1 of the curve t: Remaining life time A and B are learning coefficients and are calculated by the least squares method based on 1 total of 20 data. The remaining life time t is calculated for each measurement point by substituting the current increase magnification into e.Note 2
In this embodiment, a total of 20 pieces of data are used to improve the estimation accuracy, but at least 10 pieces of data are sufficient for estimating the remaining life time. In other words, when calculating using the least squares method, the data (time and vibration acceleration increase factor) are required to follow a normal distribution, but in practice, four or more data are required to verify that the data follows a normal distribution. data is required (central 111111 theorem), and the correlation coefficient is a parameter that determines the significance of the result calculated by the least squares method, but in this case, the population of "time and vibration acceleration increase factor" is There is a correlation (P≠0)
Since the least squares method is applied on the assumption that In order for this Z transformation to be effective, the number of data is required to be 10 or more.

Basically, the increase multiplier is 6 this time by the 1 calculation method of 1 or more.
The Hl constant of the remaining life is m until a measurement point where the above occurs
bt, but if a "breathing region" is encountered in which the current increase magnification decreases by a predetermined ratio or more with respect to the previous increase magnification, special processing is required. This is because in the "breathing region", the slope is opposite to that of the previous curve approximation, making it impossible to calculate the remaining life time. Although bearing failure appears to have stopped in this "breathing zone," it is actually steadily progressing. Therefore,
A method for identifying such a "breathing zone" and effectively treating it will be described below.

First, if the current increase rate is 5% or more lower than the previous increase rate, it is determined that the "breathing range" has been encountered. 5% of the judgment width is determined by trial j! ! As a result of the mistake,
This was derived by taking into account measurement errors, etc. "Respiratory area"
In , the measurement of the imaging acceleration intensity and the conversion of the measured value into an increase magnification are performed continuously at fixed intervals, but the calculation of the remaining life of the bearing is interrupted until the bearing exits the "breathing range". Ru. This is because accurate results cannot be obtained if the increase rate in the "respiratory zone" is used as the standard data for calculation. It is determined that the patient has moved out of the "breathing zone." and.

``When breaking out of the breathing zone J, the increase rate at time 19 immediately before entering the breathing zone is calculated as Δ(
Calculation of the remaining life time is continued by approximating the curve based on the data shifted to the spectrometer and the data at the time of leaving the "breathing zone" (20 data in total). As a result, it looks like a "breathing area"
It is possible to estimate the remaining life as accurately as if it were not available.

The remaining life estimation method described above will be specifically considered with reference to FIG. 2. First, before entering the "breathing zone", 1. The remaining life time at a point in time is determined by approximating a curve based on the increase rates of d2 and d3 to d21, and then calculating how many more years it will take to reach the "abnormal region" (an area 6 times the initial value) on the extension line of the curve. Calculate whether it is after the time. Next, move to time t8, and here again, the increase rate at the time of coughing is defined as the "current increase rate", and the increase rate d1 and the increase rate at the past 19 times (
The remaining life time is calculated based on d2 to d26). Next, the current increase rate (indicated by V in the figure) is the previous increase rate (
It is determined that the "respiratory range" has been entered when the temperature decreases by 5% or more compared to the temperature (indicated by d in the figure). Therefore, the measurement of the photographic acceleration intensity and the conversion of the measured value into an increase magnification are continued at regular intervals of m, but the calculation of the remaining life of the bearing is interrupted. Then, at time 1, ie, t3, when an increase rate (P+ in the figure) greater than the highest increase rate (dI in the figure) of the current name since the start of measurement is obtained, it is determined that the "respiratory zone" has been escaped. .

The remaining lifespan at time t3 is estimated based on the current increase rate P1 and the increase rate at time 19 immediately before entering the "breathing zone" (i.e.,
・The time required to reach the "abnormal region" by approximating the curve based on the data (d1 - d + q' in the figure) shifted forward by the period ΔL of the breathing region J (dl - d + q'), respectively. This is done by calculating. Furthermore, at the second measurement point, the remaining life is calculated by approximating the curve based on the current increase magnification P2 and the previous increase magnification P1, and the increase magnification of dl"~d,°.In this way, the remaining life is calculated. Primary “breathing area”
The remaining lifespan is calculated at each measurement point in time until the ``breathing zone'' is encountered, and if the ``breathing zone'' is re-entered, the ``breathing zone'' is processed again in the same manner as described above. Then, the above procedure is repeated until the increase factor becomes 6 or more (that is, until the abnormal range is reached), and the remaining life of the bearing at each measurement point is continued to be estimated.

The calculation results (remaining life of the bearing) for each measurement point may be displayed on the CRT 20 each time.

Needless to say, it may be printed by the printer 22. Further, various data are recorded on the floppy disk 24.

Next, a method for diagnosing abnormal vibration of one machine will be explained. Machines with rotating parts can generate abnormal vibrations not only due to bearing damage, but also due to backlash, misalignment, unbalance, etc. of the mount. This example is.

Using the function to accurately measure the shaft rotation speed, you can diagnose the cause of abnormal vibrations in a single machine by monitoring n-fold vibrations or 1/n-fold vibration frequency bands centered on the shaft rotation speed. . The causes of machine abnormalities that can be diagnosed and the monitoring frequencies are shown below.

(Cause of abnormality) (Monitoring frequency) Play of frame fr, 1/2 Xfr,
1/4 Xfr unbalance fr misalignment fr, 2xfr 3X
fr Shaft bending fr, 2x ("No blade (gear) missing tjINxfr Cr: Shaft rotation frequency (112) N: Number of blades (gear) To diagnose abnormal machine vibration, as mentioned above, it is separated using a vibration accelerometer. The low frequency component of the vibration acceleration signal (l llz =
1 kHz) is used.

Next, the effectiveness of the present application will be proved by showing the results of two types of experiments conducted by one of the inventors.

In this experiment, a roller type bearing (EC-NU204) was used.
It was used. The dimensions of the bearing are shown below.

Pinch circle diameter...D = 35.0mm Roller diameter...d = 5.510 - number of la...
...Contact angle between Z-10 shafts and rollers...α=30 degrees. Scratches having dimensions of less than one bearing were created using electric discharge precision machining with a machining accuracy of ±0.05 mm.

Length ・ ・ ・ ・ ・ ・ ・ ・ 2 , 75
+g+g depth・・・・・・・・・・・・0
, 5mm width・・・・・・・・・0.5m+g direction・
......The rotation axis and the parallel vibration acceleration detection end were screwed to a bearing box in a direction perpendicular to the rotation axis.

■ Verification of bearing destruction detection function Experiment A total of 4 types of bearings: a bearing with scratches only on the roller, a bearing with scratches only on the inner ring, a bearing with scratches on the roller and inner ring 5. A normal bearing with no scratches at all. An experiment was conducted to repeatedly measure the vibration acceleration of these four types of bearings. 50 each with a measurement interval of 10 minutes
The vibration acceleration was measured during continuous operation.

Based on the vibration acceleration measurements of the four types of bearings mentioned above,
A statistical analysis of the bearing failure detection function was performed by performing a test for the difference in variance and mean value.

The results of the statistical analysis are shown below.

(Experiment number #l) Experimental conditions: No scratches on outer ring Inner ring scratches - none Roller scratches - none ! Comparison item (1) ・I area all pass Comparison item (2)・ ・High range all bass Comparison item (3) Outer ring scratches Comparison item (4) inner ring wound Comparison item (3) Outer ring scratches Comparison item (4)・ ・Inner ring wound Comparison 1 (5) ・Roller scratches Comparison item (5)・ roller scratches Comparison item (2)・ High range all pass Comparison item (2) High range all bass Comparison item (3)・ Outer ring scratches Comparison item (4)・ ・Inner ring wound Comparison item (5)・ roller scratches Comparison item (3)・ Outer ring scratches Comparison item (4) ・Inner ring wound Comparison item (5)・ ・Roller scratches For ex-husbands, this mark indicates a significance level of 1%.

The F distribution in the table is calculated by calculating the variance ratio of each population in order to test whether there is a difference in the unbiased variance (V) of the measurement results between the population without scratches and the population with scratches. This is the value taken. Focusing on the all-bass value of the high-frequency component (1KHz to 50KHz) used to detect the location of bearing failure, experiment number #4, which had scratches on both the roller and inner ring, had a smaller F distribution value; This is because the bearing is on the verge of destruction, and the i-dynamic acceleration fluctuates rapidly, and is not considered to be an experimental error. Therefore, the following formula was used to test the difference in mean values revealed by the current measurement results, determining that there was no difference in unbiased variance.

t = x a −Y m / (J”r 1 /
n A ” 1/n m) However, JV-= S a +S @ n A ”
n s-de: Average value S: Residual sum of squares n: Number of data A: Population without scratches B: Population with scratches In the table, look at the values of one distribution calculated by the above formula It can be seen that there is a significant difference between the all-bass measurement values of the low-frequency and high-frequency components of the bearing with scratches and the all-bass measurement value of the bearing without scratches, at least at a risk rate of 1%. This shows that by measuring the full bass of the low and high frequency components, it is possible to predict failure at the stage when the bearing is damaged.

Furthermore, when comparing the vibration acceleration increase magnification of the all-bass measurement values for the low-frequency and high-frequency components, the change is more pronounced for the high-frequency components. This is due to the large energy low-frequency component due to abnormal vibrations of the machine.

This shows that high-frequency components with attenuated energy due to abnormal machine vibrations are more sensitive in detecting failure predictions of bearing components.

Next, regarding the fracture detection accuracy of the 5 bearing components, experiment number #2. #3. #4 Both parts have scratches (roller,
It can be seen that there is a significant difference in the inner circle) with a risk rate of at least 1%. This shows that by monitoring the vibration acceleration in a frequency band specific to each component, it is possible to determine where the bearing is damaged and to predict the bearing's destruction due to the damage.

■Experiment for estimating the remaining life of a bearing Using the measured values of a normal bearing with no scratches as the initial value, an acceleration test for bearing destruction was conducted based on the relative criterion method. To do this, we wiped the grease from the bearing, which had scratches with the same dimensions as above on the roller and inner ring, and accelerated the destruction of the bearing by operating the bearing without lubricating oil. At measurement intervals of 30 minutes, continuous Vt11 rotation is performed until the increase magnification of vibration acceleration exceeds 6 times, and the increase magnification of vibration acceleration intensity in the frequency bands corresponding to the low-range all bass, high-range all bass, and outer ring, inner ring, and roller is determined. was measured.

FIG. 3 shows a graph of the change over time in the vibration acceleration increase factor in the frequency band corresponding to the damage on the inner ring. From this figure,
The vibration acceleration increase factor until the bearing is destroyed is -
Instead of a continuous curve like this, the "breathing region" is repeated discontinuously, and the increase rate is accelerated (this can be observed).

Next, Figure 4 shows the results of estimating the remaining life of the bearing at each measurement point based on the vibration acceleration increase factor in the frequency band corresponding to the damage on the inner ring. Compared to the ``actual remaining life time'', which is calculated by drawing a straight line with the previous 130 hours as a --like destructive process, the predicted value is a little smaller, but from a safe perspective, the prediction is safe. Also, no problems were found in processing in the "breathing area".

It can be seen that the remaining life time can be sufficiently predicted.

The estimation of the remaining life of the bearing described above is calculated by the control microcomputer 16. The control microcomputer 16 also manages the above-mentioned periodic monitoring time, commands to select the vibration accelerometer filter, stores initial values for envelope processing, stores data on each part that makes up the bearing, and the shaft rotation speed. It has the role of automatically detecting, calculating the imaging frequency of each part that makes up the bearing, diagnosing abnormal vibrations of the machine, and controlling the screen display and printing of measurement, metering, and judgment results. The microcomputer 16 is connected to the repeater 14 by an I10 box 26.
and directly connected to the frequency analyzer to implement the above control.

[Effects] As configured as above, according to the method for estimating the remaining life of a bearing according to the present invention, the vibration acceleration increase factor in the "breathing region", which is the source of the error in estimating the remaining life of a bearing, is used as reference data for calculation. Instead, the measured value before entering the "breathing zone" is used as calculation data by shifting it by the period ΔL of the "breathing zone", so it is the same as if the "breathing zone" does not exist. It becomes possible to calculate the remaining life as a positive value at each measurement point.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a mechanical device for carrying out the bearing remaining life estimation method according to the present application. Figure 2 is an enlarged graph of the "breathing area" part, Figure 3 is a graph showing changes over time in the vibration acceleration increase factor in the frequency band corresponding to the inner ring scratches, and Figure 4 is the frequency band corresponding to the inner ring scratches. FIG. 5 is a graph showing the results of estimating the remaining life of the bearing based on the vibration acceleration increase factor. FIG. 5 is a graph showing the change over time in the vibration acceleration increase factor.

Claims (2)

[Claims] (1) Calculate the current vibration acceleration increase magnification by dividing the vibration acceleration intensity at each measurement point at arbitrary intervals detected from a rotating device containing a bearing by a predetermined initial value, and calculate the current vibration acceleration increase magnification. Then, by approximating a curve based on the vibration acceleration increase magnification obtained at a predetermined number of previous points in the past, the time until a vibration acceleration increase magnification equal to or higher than a predetermined value is obtained is calculated for each measurement point. In a method for estimating the remaining life of bearings. If the current vibration acceleration increase rate decreases by a predetermined ratio or more with respect to the previous vibration acceleration increase rate, it is assumed that the vibration acceleration has entered the "breathing range" and calculation of the remaining life from that point on is interrupted, At the point when the highest ever vibration acceleration increase ratio is obtained, it is assumed that the "breathing range" has been reached. The bearing is calculated by approximating a curve based on the vibration acceleration increase magnification in A method for estimating the remaining life of a bearing, characterized by restarting calculation of the remaining life of the bearing. (2) The method for estimating the remaining life of a bearing according to claim 1, characterized in that when the current measurement value decreases by 5% or more from the previous measurement value, it is considered to have entered the "breathing range". .