JPS60357A - Measuring device of acoustic emission - Google Patents

Abstract

PURPOSE:To eliminate noise precisely and to measure acoustic emission (AE) correctly by preparing two AE detecting systems having equal characteristics, and only when noise is detected by one AE detecting system, stopping an output from another AE detecting system. CONSTITUTION:The AE detecting sensors 9, 10 have almost the same characteristics, the AE detecting sensor 9 in an AE detecting part 4 is fitted to a bearing box 2 so as to detect AE from a test bearing 3 and the AE detecting sensor 10 in a noise detecting part 12 is arranged on a position close to the AE detecting sensor 9 and prevented from the transmission of the AE from the test bearing 3. The switching of a gate circuit 13 is controlled by a discriminator 16 in the noise detecting part 12, and at the detection of noise, the gate circuit 13 is opened and the output of the AE detection part 4 is stopped. Thus, the noise can be removed precisely and correct AE measurement can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION AE (Acoustic Emission) is a type of sound generated by the destruction of a material, and the occurrence of this AE is detected to detect and test material destruction.

In conventional materials inspection equipment that uses AE detection, a ΔF detection sensor (transducer) is installed at a position that has a propagation relationship with the object to be measured, and the AE detection sensor detects the object to be measured. It detects the AE from the sensor, converts it into an electrical signal, and outputs it.

However, such A [in the measurement, during the measurement of 8E,
Because noise, which is environmental noise similar to the properties of 8E, enters from outside the measurement system and is measured, information that is trying to be measured is often buried in the noise, especially in factories. When measuring △ in places with a lot of electrical or mechanical noise, such as C), this tendency is noticeable, and accurate △ measurements are difficult.

Therefore, conventional techniques for removing this noise include the filter method that distinguishes the A signal from the noise based on the frequency, the position location method that distinguishes the ΔlE signal from the noise based on the signal generation position, or the time difference Spatial filter methods have been developed to distinguish between AE signals and noise based on their shapes and shapes, but it is difficult to distinguish and remove just the noise, the equipment for discrimination is complicated, or special This method is effective only for objects to be measured that have a structure, and has not always been satisfactory.

The present invention was made in view of the above circumstances, and provides an AE measurement device that can reliably remove noise, has a simple structure, is easy to implement, and particularly enables accurate AE measurements. The purpose is to provide

In order to achieve this purpose, the AE measurement device of the present invention includes two AE detection systems having the same characteristics, and connects the AE detection sensor of one of the two AE detection systems to the object to be measured. The AE detection sensor of the other AE detection system is arranged at a position near the AE detection sensor of the one AE detection system and where AE does not propagate from the object to be measured. The present invention is characterized in that the output of the one E detection system is stopped only when noise is detected in the other AE detection system.

The details of the present invention will be described below with reference to an embodiment in which the invention is applied to an AE measuring device for detecting abnormalities in rolling bearings.

In FIG.
It is something that is covered when trying to measure.

The AE measurement device 1 includes a ΔE detection section 4, a noise removal device 5, and an output device 6.

The AE detection section 4 includes an AE detection sensor 9 (AE converter), a preamplifier 7, a filter main amplifier 8, and a discriminator 11.

The noise removal device 5 includes a noise detection section 12 and a gate circuit 13.
It is equipped with

The noise detection unit 12 includes an E-detector 4/10 (ΔF-converter), a preamplifier 14, a filter main amplifier 15, and a discriminator 16.

It is assumed that the AE detection sensor 9 and the AE detection sensor 0 have almost the same characteristics. The preamplifier 7 and the preamplifier 14 each amplify the output of the AE detection sensor +19.10, and are assumed to have approximately the same characteristics.

The filter main amplifier 8 and the filter main amplifier 15 each filter and amplify the output of the preamplifier 7.14, and have almost the same characteristics. Further, the discriminator 11 and the discriminator 1G are each a filter main amplifier ε
3.15 is used to discriminate ΔF from the output using a threshold value, and they have almost the same characteristics. And, the AE detection section 4
and the noise detection unit 12 have almost the same characteristics as A[
Detection system J: Urchin 4f11 is formed.

The AE detection sensor 9 of the AE detection section 4 is attached to the bearing box 2 and arranged so as to be able to detect AE from the test bearing 3. The Δ[detection lens 1 and 10 of the noise detector 12 are arranged in the vicinity of the ΔE detection resistor 9 and at a position where AE is not propagated from the test bearing 3.

The AE detector 4 connects to the output device [iI6] via the gate circuit 13.
Connect to. The output device @6 includes, for example, a counter 18, a recorder 21, a waveform storage device 22, an oscilloscope 23, and the like. The discriminator 11 of the AE detector 4 is connected to the counter 18 via the gate circuit 13, and also connected to the filter main amplifier 8.
I is connected to the waveform storage device 22 via the gate circuit 13. Then, circuits 1 to 13 are closed (discriminator 11 when present), and C filter main amplifier 8 is connected to counter 1.
ε3, output to waveform storage device 22, but goo 1 - circuit 1
Poetry 3 is developed is blocked from such output I.

The opening/closing of the circuits 1 to 13 is performed by the discriminator 1 of the noise detection unit 12.
G is controlled by J, and when the noise detection section 12 detects noise (the circuits 1 to 13 are opened).

As shown in FIG. 2, the gate circuit 13 includes a j7s1-I gate 24, a gate/time setting circuit 25, a delay circuit 26,
Pulse game 1-27 to 4111 bookmark, goo 1
~The time and the delay time can be appropriately selected as needed. The operation timing of the goo 1-circuit 13 is as shown in FIG.

Next, the operation of this measuring device N configured as shown in FIG.

Figure 4 shows a test device consisting of an output device ÷ 4 and a counter 18.
a, 18b, 18c 1 recorder 218121b, 2
1c connected as shown in the figure was used.

Looking at the AE analog signal, when the noise removal device is not operating, as shown in Figure 5a, the noise contained in the output (b) of the noise detection section is output from the AEE output section after passing through the noise removal device. It is also included in the output (a). However, when the noise removal device is operating, as shown in Figure 5, the output from the AEE output section (A) after passing through the noise removal device is the same as before (B), while the output from the noise detection section (B) is the same as before. The noise part is cut out and only the AE is left.

Next, regarding the AE pulse signal, FIG. 6 shows the situation of the AE pulse signal when the noise removal device is operating. As shown in the output (b) of the recorder 210 in FIG. 6, although the noise removal device detects noise, the output of the recorder 218 from the AEE output section after passing through the noise removal device ( In a), the noise part is reduced and only AE is left.

As is clear from the above description, the present invention provides an AEE determination device that can reliably remove noise, has a simple structure, is easy to implement, and enables particularly accurate AE measurements. be able to.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of an AEE measuring device according to an embodiment of the present invention, Fig. 2 is a block diagram showing circuits from 1 to 1, and Fig. 3 is a timing diagram showing the operation timing of the AE measuring device. , FIG. 4 is a block diagram showing the configuration of the AEE constant device used in the test, FIG. 755 is a graph showing the analog output of the AE, and FIG. 6 is a graph showing the pulse output of the AE. 1... AE measurement device @ 4... AEE output section 5...
Noise removal device 9.10...AE test detection Shin 1 no 1
2. Noise detection section 13. Gate circuit 7.14.
...Preamplifier 8,15...Filter main amplifier 1
1.16...Discriminator 41F iI! iQ 耶,,,F: No. Y beak former ma length

Claims (1)

[Claims] Two AE detection systems with the same characteristics are provided, and the AE detection sensor of one of the two AE detection systems is disposed at a position where ΔF propagates from the object to be measured, and the A
The AE detection sensor of the E detection system is connected to the A of the one AE detection system.
It is arranged near the E detection sensor at a position where AE does not propagate from the object to be measured, and the output of the one AE detection system is stopped only when noise is detected in the other AE detection system. An AE measurement device characterized by the following configuration: