JPS605893B2 - Bearing abnormality monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing abnormality monitoring device, and an object of the present invention is to detect damage such as peeling in a bearing that rotates under load, and to effectively display and warn the extent of the damage. It is.

Rolling bearings, etc., may develop abnormalities such as peeling or seizure on the raceway surface due to abnormal usage conditions or fatigue life. It is generally known that impulse-like impact motions occur at specific cycles or randomly.

Since the degree of damage to the bearing is highly correlated to the acceleration component of the impulse shock vibration described above, various means for detecting this impulse shock vibration have conventionally been used as means for detecting damage to the bearing. are being taught. One way to do this is to convert the above-mentioned impulse shock vibration into an electrical signal using a vibration pickup, and detect an abnormality in the bearing by distinguishing the amplitude. In this case, the pulse width of the detection pulse is Since the area is very narrow, the peak level of the pulse signal must be maintained for a certain period of time in order to be displayed on a slow-operating analog meter such as an ammeter. However, the peak level of the shock vibration that occurs when the Fuji Uke is abnormal is not constant and constantly fluctuates, so in order to accurately display the peak amplitude of the pulse signal, it must be reset one after another. As a specific example of performing such an operation, one is already known in which the peak value of the signal that first enters within one cycle is held, reset at the end of that cycle, and this operation is repeated periodically. However, this example has the following problems. That is, in the above example, if it is assumed that the period of occurrence of impact vibration due to damage to the bearing coincides with the rotation period of the bearing, a sufficient effect can be achieved by matching the above-mentioned reset period with the rotation period.
As mentioned at the beginning, there are various occurrence cycles of shock vibrations caused by bearing damage, and some of them are random and do not have periodicity, so the reset cycle is determined by the occurrence of shock vibrations caused by bearing damage. It is clear that the operation of adjusting to the period is not only substantially difficult, but also that its effectiveness is halved if shock vibrations with different periods occur in combination. The present invention performs a peak sampling operation that constantly updates and stores the maximum amplitude of the input signal in the previous half cycle after converting impulse shock vibration caused by bearing damage into an electrical signal, and then performs a peak sampling operation that constantly updates and stores the maximum amplitude of the input signal in the previous half cycle. By inputting the input into a so-called peak sampling and hold circuit, which performs periodic repetition of two types of operations that maintain the maximum amplitude at a sufficiently long period relative to the rotation period of the bearing, the problems seen in the above example can be solved. An object of the present invention is to provide a bearing abnormality monitoring device that can eliminate the problem and accurately detect the degree of damage to a bearing.

To explain the embodiment, in Fig. 1, 1 is a vibration pickup fixed at an appropriate position such as the bearing box A.
If an abnormality such as peeling occurs in the test bearing B while it is rotating under an appropriate load, mechanical vibrations, including vibrations due to the bearing damage described above, are picked up and converted into electrical signals.

The output signal from the pickup 1 is amplified by the next amplifier 2 to an appropriate level that is easy to process, and then applied to a radio wave generator 3 set in an appropriate frequency range. The furnace wave device 3
As a result, the output signal obtained by removing the influence of vibrations caused by other mechanical elements from the signal caused by impulse shock vibration caused by abnormality in bearing B has a waveform as shown in Fig. As a result, the waveform shown in Fig. 2b is obtained.The output signal from the detector 4 is converted by the peak sampling and hold circuit 5 into the waveform shown in Fig. 2d. Activate it,
The degree of abnormality of the test bearing B is displayed.

To explain the function of the peak sampling and hold circuit 5 in detail, this circuit constantly updates the maximum amplitude of the input signal, performs a peak sampling operation to store it, and holds the peak value captured by that operation. The hold operation without a value detection operation is performed alternately at time intervals according to the timing of the rectangular wave from the rectangular wave generating circuit 7 with a cycle shown in FIG. This is what I did.

That is, in FIG. 2c, the peak sampling operation is performed at the "4" level, and the hold operation is performed at the "0" level. Although not shown in the drawings, an amplitude discrimination circuit may be provided downstream of the peak sampling and hold circuit 5 to which an appropriate zero-bell setting has been made in advance, and the output of the circuit may automatically issue a bearing abnormality alarm.

According to the present invention, by setting the time interval 3L of the above-mentioned peak sampling operation to be sufficiently long with respect to the rotation period of the bearing, most of the impact vibrations due to bearing damage having various occurrence periods are picked up and detected. This allows the degree of damage to the bearing to be accurately read from the indicator.

In addition, during the hold operation time interval: t2, no input signal is accepted, so even if a sudden disturbance signal is input during this period, the possibility of erroneously sensing vibration components due to disturbance elements is halved, and bearing damage is detected. In addition to improving the reliability of the indicator, the time it takes to hold the indicated value at the peak level, which displays the status numerically, is sufficiently long compared to the holding time of the known sequential reset peak hold method. This provides the advantage of being able to easily and stably determine pass/fail.

Also, since no vibrations are accepted during the above holding period, it is possible that abnormal vibrations of the bearing are not detected, but the period of vibration (pulse) that occurs when the bearing is damaged is
This is much shorter than the holding cycle, and occurs repeatedly at a fraction of the rotational cycle of the bearing.
There is no fear that it will not be detected.

[Brief explanation of drawings]

Figure 1 is a block diagram of the embodiment, Figure 2 is the block diagram of the first embodiment.
It is a figure which shows the output waveform in each part of a figure. 3...Obijo wave detector, 4...Full wave detector, 5...
...Peak sampling and hold circuit, 6.
...Indicator, 7...Square wave generator. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a device that converts the mechanical vibration generated from a rotating bearing under load into an electrical signal to detect abnormalities such as damage to the bearing and issue an alarm, a pulse signal corresponding to impact vibration caused by abnormality in the bearing is used. a bandpass filter that extracts the pulse signal, a full-wave detector that full-wave rectifies the pulse signal, a peak sampling operation in the first half cycle that constantly updates and stores the maximum amplitude of the input signal, and a peak sampling operation that stores the maximum amplitude due to this operation. A peak sampling and hold circuit that periodically repeats two types of operations: a hold operation in the second half of the cycle in which the peak value is held and no peak value detection operation is performed, and the periodic operation of this circuit is performed at a sufficiently long period relative to the rotation period of the bearing. and a rectangular wave generator that generates a timing signal to indicate and discriminate the output signal of the peak sampling and hold circuit to detect an abnormality in the rotating bearing and issue an alarm. Bearing abnormality monitoring device.