JPH01118767A - Ae sensor breakage detecting device - Google Patents

Abstract

PURPOSE:To detect the breakage of an acoustic emission sensor by comparing a mean value signal outputted by an averaging circuit with a reference value by a 1st comparator, comparing the output of a counter with a reference value by a 2nd comparator, and providing an OR circuit which ORs the outputs of the 1st and 2nd comparators and outputs a sensor breakage signal. CONSTITUTION:The mean value signal corresponding to the level of the back noise of an AE signal outputted by the AE (acoustic emission) sensor 1 is calculated by the mean value circuit 3. This mean value signal is compared by the 1st comparator with the reference value indicating a constant back noise and a continuance decision circuit 5 detects the state the time wherein the AE signal exceeds the reference time being shorter than a constant time. The number of times of generation at this time is counted 6 and this counted value is compared by the 2nd comparator 7 with the reference value to detect the generation of electric noises more than a constant quantity. Then the OR circuit ORs the outputs of the comparators 4 and 7 and outputs the breakage signal of the sensor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an AE sensor damage detection device for detecting damage to an AE sensor that detects acoustic emissions (hereinafter referred to as AE) in a rolling mill or the like.

<Prior Art> For example, an equipment diagnosis device for a rolling mill diagnoses a rolling mill by analyzing an AE multiplied signal from the rolling mill detected by an AE sensor. And this AE
The detection surface of the sensor is made of alumina plate and is easily damaged, so the AE sensor must be removed and inspected periodically.

<Problems to be Solved by the Invention> By the way, in a rolling mill, since the impact during rolling is large, the AE sensor may be suddenly damaged. in this case,
If the AE sensor is removed and inspected periodically as in the past, the equipment diagnostic device will continue diagnosing the rolling mill without noticing damage to the sensor, resulting in incorrect diagnosis of the rolling mill and causing serious damage. There are cases.

Therefore, this invention focuses on the phenomenon that when an AE sensor is damaged, the sensitivity is extremely reduced or electrical noise occurs frequently, and the present invention has developed an AE sensor that can immediately detect damage to the AE sensor.
The purpose is to provide a sensor damage detection device.

Means for Solving the Problems In order to achieve the above object, the AE sensor damage detection device of the present invention provides an AE sensor damage detection device for detecting acoustic emissions.
an averaging circuit for calculating an average value of the AE multiplied signal output from the AE sensor; a first comparing means for comparing the average value signal output from the averaging circuit with a reference value; a duration determination circuit that receives the signal and calculates the duration of the state in which the AE multiplied signal exceeds a predetermined reference value, and detects when the duration does not exceed a certain time and outputs a signal; A counter for counting the output of the duration determination circuit, a second comparison means for comparing the output of the counter with a reference value, and a logical sum of the output of the first comparison means and the output of the second comparison means. and an OR circuit that outputs a sensor damage signal.

Effect> If the alumina plate on the detection surface of the AE sensor is damaged, the AE sensor will emit frequent short-lived electrical noises due to the release of static electricity. Furthermore, if the AE sensor is damaged, the sensitivity will decrease and the amplitude of back noise will decrease.

An average value of back noise is calculated by an AE multiplied signal averaging circuit detected by the AE sensor. This average value signal representing the average value of the back noise is compared with two predetermined reference positions by the first comparison means, and when the average value of the back noise is smaller than the reference value, it is determined that the sensitivity of the AE sensor has decreased. Outputs a signal representing the On the other hand, A.E.
The signal is input to the double signal duration determination circuit, the duration of the AE double signal exceeding a predetermined reference value is calculated, and if this duration does not exceed a predetermined time period for identifying electrical noise, A pulse representing the occurrence of noise is output. A counter counts how many pulses are generated in a predetermined period of time, and a second comparing means compares the output of this counter with a reference value. That is, the second comparing means compares the number of occurrences of electrical noise input from the counter with a predetermined reference value, and if the number of occurrences of electrical noise is greater than the reference value, it indicates that electrical noise has occurred frequently. Outputs a signal representing .

The signal indicating that the level of back noise output from the first comparing means has decreased and the signal indicating that electrical noise has occurred frequently output from the second comparing means are input to an OR circuit, and the OR circuit outputs a signal indicating that the level of back noise has decreased. A sensor damage signal indicating that the sensor is damaged is output when either the back noise is decreasing or the electrical noise is occurring frequently.

In this way, damage to the AE sensor is reliably detected.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a block diagram of an AE sensor damage detection device added to an equipment diagnosis device 2 for a rolling mill. AE from a rolling mill or the like is detected by an AE sensor 1, and an AE multiplier signal output from the AE sensor 1 is input to an equipment diagnostic device 2.

The equipment diagnostic device 2 performs predetermined processing on the AE multiplied signal to diagnose the rolling mill. In addition, the AE from the AE sensor 1 is
The signal is input to the double signal averaging circuit 3. This averaging circuit 3 is composed of, for example, an integrating circuit or an effective value detection circuit, and outputs an average value signal representing an average value in some sense.

This average value signal represents the amplitude of the AE multiplied signal back noise. The average value signal outputted from the averaging circuit 3 is inputted to a first comparator 4 as a first comparing means, and is compared with a predetermined reference value in the first comparator 4 to determine the level of the average value signal. When becomes lower than the above reference value, a high level signal is output. On the other hand, the AE multiplied signal from the AE sensor 1 is input to the duration determination circuit 5. Although not shown, this duration determination circuit 5 is composed of an envelope detection circuit, a comparator, and an integration circuit. The AE multiplied signal envelope detection circuit detects the envelope, and the envelope detection signal is converted to a predetermined standard by the comparator. The duration in which the envelope detection signal exceeds the reference value is detected by an integrating circuit, and the signal representing the detected duration is compared with a reference signal representing a certain period of time by a comparator. , outputs a pulse to the counter 6 when the duration is shorter than the predetermined time. The counter 6 counts the pulses inputted within a predetermined time from the duration detection circuit 5, and outputs a signal representing the count value to a comparator 7 as a second comparing means.

This count value represents the frequency of occurrence of electrical noise. The count value output from the counter 6 is compared with a predetermined reference value by a second comparator 7 as a second comparing means, and if the count value is larger than the reference value, that is, the number of occurrences of electrical noise. is greater than a certain value, the second comparator 7 outputs a high level signal. The outputs of the first comparator 4 and the second comparator 7 are input to the OR circuit 8, and when the sensitivity of the AE sensor 1 decreases and the back noise level becomes lower than a certain value, or when the AE sensor 1 If noise occurs more than a certain number of times, AE
Outputs a high level sensor failure signal indicating failure of sensor l.

If the AE sensor 1 is damaged in this way, the level of back noise will drop more rapidly than the back noise that is normally detected. As a result, electrical noise occurs frequently, so damage to the AE sensor 1 is monitored by monitoring the number of electrical noises that occur.

Since damage to the AE sensor l is detected by the AE sensor damage detection device in this way, the equipment diagnosis device 2 detects damage to the AE sensor l.
In the above embodiment, the duration discrimination circuit 5 is composed of an envelope detection circuit, an integrating circuit, a comparator, etc., but this duration discrimination circuit is composed of an envelope detection circuit, a comparator, etc. The duration may be detected by a gate that opens and closes according to the output of this comparator and a counter that counts the clocks that have passed through this gate. Furthermore, although the above embodiments are configured using individual electric circuits, they may also be configured using microcomputer software.

<Effects of the Invention> As is clear from the above, the AE sensor damage detection device of the present invention calculates an average value signal corresponding to the level of the AE multiplied signal back noise output from the AE sensor using an averaging circuit, and The average value signal is compared with a reference value representing a constant back noise by the first comparison means to determine a decrease in the level of back noise, and if the duration of the AE multiplied signal exceeding the reference value is less than a certain time, A state in which electrical noise occurs more than a certain number of times is detected by detecting it by a duration discrimination circuit, counting the number of occurrences by a counter, and comparing this count value with a reference value by a second comparing means. and the first comparison means and the second
By ORing the output with the comparison means using an OR circuit, a sensor damage signal is output, so a drop in the level of back noise or frequent occurrence of electrical noise is detected and the AE is activated.
Damage to the sensor can be detected reliably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an AE sensor damage detection device according to the present invention. 1... AE sensor, 2... Equipment diagnosis device, 3...
...Averaging circuit, 4...First comparator, 5...
Duration determination circuit, 6... Counter, 7... Second comparator, 8... OR circuit.

Claims (1)

[Claims] (1) An AE sensor that detects acoustic emissions, an averaging circuit that calculates the average value of the AE signals output from the AE sensor, and an averaging circuit that compares the average value signal output from the averaging circuit with a reference value. 1 comparing means, receiving the AE signal, calculating the duration of the state in which the AE signal exceeds a predetermined reference value, and detecting the case where the duration does not exceed a predetermined time and outputting the signal; a duration determination circuit for outputting an output, a counter for counting the output of the duration determination circuit, a second comparison means for comparing the output of the counter with a reference value, and a second comparison means for comparing the output of the first comparison means with a second comparison means. An AE sensor damage detection device comprising: an OR circuit that performs a logical OR with the output of the AE sensor damage detection device and outputs a sensor damage signal.