JP3415296B2 - Diagnosis method for bearing abnormalities - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AE in which a bearing is generated.
The present invention relates to a bearing abnormality diagnosis method for detecting (acoustic emission) and periodically diagnosing a bearing abnormality. 2. Description of the Related Art Conventionally, as an abnormality diagnosis method for a bearing of this kind, an AE generated by the bearing is detected and measured by an AE sensor, and AE signals from the AE sensor are totalized and subjected to periodic analysis. Some periodic analysis diagnosis is performed periodically. [0003] However, the low-speed rotating body
(100 rpm or less) generates a large amount of AE, or when noise occurs, a large amount of time is spent collecting the AE signals. Therefore, in this case, since the measurement start time of the next periodic diagnosis comes before the above aggregation is completed, there is a problem that the periodic diagnosis cannot be reliably performed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of diagnosing an abnormality of a bearing which can prevent a mistake in a periodic diagnosis. In order to achieve the above object, a method for diagnosing an abnormality of a bearing according to the present invention detects an AE generated by the bearing with an AE sensor and outputs the AE from the AE sensor.
In a bearing abnormality diagnosis method for periodically diagnosing a bearing abnormality at predetermined time intervals based on a signal, a step of setting the time interval of the periodic diagnosis, and an AE signal from an AE sensor in one periodic diagnosis. Setting the measurement time for measuring the AE signal, calculating the expected maximum number of AE signals occurring within the set measurement time, and calculating the total time required to total the maximum number of AE signals. A step of calculating, a step of determining whether or not an addition time obtained by adding the measurement time and the total time exceeds the time interval of the periodic diagnosis, and a step of determining whether the addition time exceeds the time interval of the periodic diagnosis. Outputting a warning indicating that the time interval of the periodic diagnosis is insufficient when it is determined that there is a time interval. According to the above-mentioned invention, A in one periodic diagnosis
The addition time, which is the sum of the measurement time for measuring the E signal and the total time required for totalizing the maximum number of AE signals expected to occur within the measurement time, exceeds the time interval of the periodic diagnosis. When it is determined that there is an alarm, an alarm indicating that the time interval of the periodic diagnosis is insufficient is output. Therefore, according to the present invention, it is possible to know before the periodic diagnosis that there is a high possibility that the preset time interval of the periodic diagnosis is insufficient. Therefore, if the time interval of the periodic diagnosis is extended when the alarm is received, the risk of the shortage of the time interval can be avoided beforehand. Therefore, according to the present invention, it is possible to avoid a mistake in setting the time interval of the periodic diagnosis of the bearing, and to perform the periodic diagnosis without fail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 2 shows a block diagram of an abnormality diagnosis apparatus for diagnosing a bearing abnormality by the bearing abnormality diagnosis method of the present invention. This abnormality diagnosis device includes an AE sensor 1, a preamplifier 2, a bandpass filter 3, a main amplifier 4, an envelope detection circuit 5, and a computer 6. A
The E sensor 1 detects an AE generated by the bearing and outputs an AE signal. This AE signal is amplified by the preamplifier 2,
Only a predetermined band component is passed by the band pass filter 3, further amplified by the main amplifier 4, and then subjected to envelope detection by the envelope detection circuit 5. This envelope detected AE signal is input to the computer 6. The computer 6 performs signal processing according to the flowchart shown in FIG. First, in step S1, a time interval T for periodically diagnosing a bearing is initially set. The number of averaging is set to n = N. Next, in step S2, it is determined whether or not to perform the periodic measurement. When it is determined that the periodic measurement is to be performed, the process proceeds to step S3, and when it is determined that the periodic measurement is not to be performed, the periodic diagnosis ends. In step S3, the type of the bearing to be diagnosed is selected, or the specifications of the bearing are input to the computer 7. Then, the process proceeds to a step S4, wherein a characteristic cycle of each part of the bearing is calculated. Among these characteristic periods, the largest characteristic period is the rolling element revolution period tc, and the smallest characteristic period is the period ti in which one rolling element passes through the inner ring. Next, proceeding to step S5, 3tc, which is three times the rolling element revolution period tc, is set as the measurement time ts in one periodic diagnosis. The reason that the measurement time ts is set to be three times the maximum characteristic period tc in step S5 is to ensure that at least two rolling element revolution periods tc can be measured within the measurement time ts. Next, proceeding to step S6, the measurement time ts is divided by 70% of the minimum characteristic period ti, and a value obtained by multiplying the divided value by 4 is calculated as a maximum expected A.
Let E be the number of occurrences Nmax. That is, Nmax = (measurement time t
s) ÷ (minimum characteristic period ti × 0.7) × 4. The above 70% is a value determined by the slip generated in the bearing, and the above 4 is a value when it is assumed that the inner ring and the outer ring have two flaws respectively. The above 70%
The value of 4 can be changed according to the accuracy of the bearing and the situation in which the bearing is used. Next, in step S7, the processing time Tp is calculated by the following equation using the predicted maximum number of AEs Nmax. Processing time Tp = ｛(1/2) × Nmax × (Nma
x-1)｝ × 90 μs The value in the curly brackets in the above formula indicates the number of combinations of the total calculation for Nmax AE signals, and the above 90 μsec indicates the time required for one total calculation. Therefore, for example, when Nmax = 1142, the processing time Tp = 1114 × (1142-1) ÷ 2 × 90 μsec = 5
8 seconds. Since the processing time of 90 μs depends on the performance of the computer 7, its value is changed depending on the difference in the operation unit of the computer 7. Next, the process proceeds to step S8, in which the measurement time ts and the processing time Tp are added, and the measurement processing time t
Calculate sp (tsp = ts + Tp). Next, in step S9, the maximum measurement processing time tmax is calculated by multiplying the measurement processing time tsp by the number of averagings n = N (tmax = N × tsp). Next, the process proceeds to step S10,
The time interval T of the periodic diagnosis initially set in step 1 is compared with the maximum measurement processing time tmax. When it is determined that the time interval T is longer than the maximum measurement processing time tmax, the process proceeds to step S13, T is the maximum measurement processing time t
When it is determined that it is not larger than max, step S11
Proceed to. In step S11, a warning display indicating that it is highly likely that the measurement of the AE signal and the aggregation of the measured AE signal cannot be completed within the time interval T of the periodic diagnosis is high. Next, the process proceeds to step S12, where it is determined whether or not to perform the periodic diagnosis. When it is determined that the periodic diagnosis is to be performed, the process proceeds to step S13. When it is determined that the periodic diagnosis is not to be performed, the process returns to step S2. In step S13, the AE signal is periodically measured. Next, the process proceeds to step S14, where the measured AE signals are totaled for each cycle. Next, the process proceeds to step S15,
The averaging count n is incremented by 1 (n = n +
1). Next, the process proceeds to step S16, where it is determined whether or not the number of averagings n has reached a predetermined number of times N.
When it is determined that the number has not reached, the process returns to step S13. In step S17, A for each cycle calculated N times
The number Mi of E signals is divided by the number of times N and averaged. Next, in step S18, the number (Mi / N) of the AE signals averaged by the averaging process is compared with a predetermined reference value, and the number (Mi / N) exceeding the reference value is obtained.
From the AE signal of N), a component in which an abnormality has occurred is detected. Then, the process proceeds to a step S19, and the detection result of the abnormal component is displayed. Next, the process proceeds to step S20, where
It is determined whether or not the periodic measurement is set at the time of the initial setting in step 1. If it is determined that the periodic measurement is set, the process proceeds to step S21, and the setting is made to perform the periodic measurement. If it is determined that the diagnosis has not been made, the diagnosis is terminated. In step S21, it is determined whether or not a forcible termination instruction has been issued by a key interrupt. If it is determined that a forcible termination instruction has been received, the process ends. If it is determined that there has been no forcible termination instruction, step S2 is performed.
Proceed to 2. In step S22, it is determined whether or not the next periodic measurement start time has come. When it is determined that the start time has come, the process returns to step S13, and when it is determined that it is not the start time, the process returns to step S21. As described above, according to this embodiment, the measurement time Ts set based on the minimum characteristic period ti of the bearing is set.
Is calculated, the processing time Tp required to count the AE signals of the maximum AE occurrence number Nmax is calculated, and the processing time Tmax is calculated.
A value tmax obtained by multiplying the sum of p and the measurement time Ts (Tp + Ts) = t by the number of averaging N is calculated. A warning indicating that there is a high possibility that the time interval is insufficient is displayed. Therefore, according to this embodiment, it is possible to know from the warning display in advance that the time interval T of the periodic diagnosis is likely to be insufficient before the periodic diagnosis. Therefore, when the warning display is received, if the time interval T of the periodic diagnosis is extended, the danger of the shortage of the time interval T can be avoided. Therefore, according to this embodiment, it is possible to avoid a mistake in setting the time interval of the periodic diagnosis of the bearing, and to perform the periodic diagnosis without fail. As is apparent from the above description, the method for diagnosing abnormality of a bearing according to the present invention provides a measurement time for measuring an AE signal in one periodic diagnosis, and a maximum number of AEs generated within the measurement time. When it is determined that the addition time, which is obtained by adding the total time required to total the signals, exceeds the time interval of the periodic diagnosis, an alarm indicating that the time interval of the periodic diagnosis is insufficient is output. Therefore, according to the present invention, it is possible to know before the periodic diagnosis that there is a high possibility that the preset time interval of the periodic diagnosis is insufficient. Therefore, if the time interval of the periodic diagnosis is extended when the alarm is received, the risk of the shortage of the time interval can be avoided beforehand. Therefore, according to the present invention, it is possible to avoid a mistake in setting the time interval of the periodic diagnosis of the bearing, and to perform the periodic diagnosis without fail.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing an embodiment of a bearing abnormality diagnosis method according to the present invention. FIG. 2 is a block diagram of an abnormality diagnosis device used in the embodiment. [Description of Signs] 1 AE sensor, 2 preamplifier, 3 bandpass filter, 4 main amplifier, 5 envelope detection circuit, 6 computer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-116526 (JP, A) JP-A-58-108419 (JP, A) JP-A-58-123440 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01M 13/04 G01M 19/00 G01N 29/14 G01H 17/00

Claims (1)

(57) Claims 1. An AE generated by a bearing is detected by an AE sensor, and based on an AE signal from the AE sensor, abnormality of the bearing is periodically determined at predetermined time intervals. In the method for diagnosing abnormality of a bearing to be diagnosed, a step of setting a time interval of the periodic diagnosis, a step of setting a measurement time for measuring an AE signal from the AE sensor, and an AE signal generated within the set measurement time Calculating the maximum number of predicted AE signals; calculating the total time required to total the maximum number of AE signals; and adding the measurement time and the total time to the periodic diagnosis. Determining whether or not the time interval exceeds the time interval of the periodic diagnosis. If it is determined that the addition time exceeds the time interval of the periodic diagnosis, an alarm indicating that the time interval of the periodic diagnosis is insufficient is issued. Abnormality diagnosis method of a bearing, characterized in that it comprises a step of.