JPS6021796Y2 - Device for measuring the location of vibration sources and their frequency of occurrence - Google Patents

Description

[Detailed description of the invention] This invention detects physical phenomena that propagate from the location of occurrence to the surroundings over time, such as sound waves, ultrasonic waves, and waves on the water surface, and measures the location of occurrence and the frequency of occurrence at each location. In particular, the present invention relates to a device for measuring the location and frequency of defects in materials using acoustic emission, which is a type of non-destructive testing of materials.

Recently, there are cases where the reliability of materials is strictly required, such as in space equipment and nuclear power generation equipment, and the acoustic emission method has attracted attention as a non-destructive method for inspecting the initial minute scratches that lead to material destruction. ing.

This is based on the phenomenon that ultrasonic waves are emitted from minute cracks inside the material during the process of increasing stress when a load is applied to the material, and these ultrasonic waves are detected at at least two points on the material surface to locate the sound source. The purpose is to detect the location of defects in the material by calculation.

Conventionally, computers have been used exclusively as data processing means to detect sound waves generated from this defect and calculate the sound source location.For example, if sound detectors are installed at A82 locations, one sound detection The frequency of occurrence for each sound source position was measured by calculating the position of the sound source by performing calculation processing, specifying the memory corresponding to this position in a program, and counting up the contents of that memory.

However, in this method, the sound source position is calculated according to a program, which requires time to execute the program, and has the drawback that detection errors may occur if acoustic emissions occur continuously, and the burden on the computer is large. Therefore, there is a drawback that the apparatus is large-scale and expensive.

This invention solves the above-mentioned drawbacks by directly and simply calculating the position of a sound source, etc., which was conventionally done by a computer, thereby eliminating detection errors and creating a compact and inexpensive measuring device. It provides:

Next, a case will be described in which this invention is applied to an inspection device for rod-shaped materials.

FIG. 1 is a circuit diagram of this embodiment.

A first sound wave detector 2A and a second sound wave detector 2B are attached to both ends of the material 1 to be inspected, where the signal is converted into an electrical signal and introduced into the time difference calculation circuit section 3.

The time difference calculation circuit section 3 is a circuit section that receives the signals from the sound wave detectors 2A and 2B and immediately issues an output signal representing the sound source position, and includes an arrival order determination circuit 4, an arrival time difference detection circuit 5, and an AND
It consists of a gate circuit 6.7 and a reversible counter 8 with preset.

The arrival order determining circuit is configured to output an output C when the input signal A arrives before the signal B, and conversely output an output C when the input signal B arrives before the signal A.

Further, the arrival time difference detection circuit 5 generates an output signal E having a time width corresponding to the arrival time difference Δt between the input A and the input B.

The AND gate circuit 6 is opened for a time Δt only when the signal C is issued, and introduces the clock signal CL into the up-count terminal of the counter 8.

The AND gate circuit 7 is opened for a time Δt only when a signal is issued, and introduces the clock signal CL into the down-count terminal of the counter 8.

The reversible counter 8 with preset is a counter that has a preset terminal PS and calculates the number of input pulse signals from the up-count terminal and adds it to the stored content, and calculates the number of input pulse signals from the down-count terminal and subtracts it from the stored content. In the embodiment, for simplicity of explanation, it has a storage capacity of 10 bits, so 2'' = 1.
024 states.

When the frequency f of the clock signal CL is constant, the distance can be immediately determined from the calculated value of the pulse once the sound velocity V in the material to be inspected is determined.

For example, f = IMHz, V = 2400yrL/
In the case of s, the period of the clock pulse is lμS, and the sound wave travels 2.4 degrees in one period.

By making the frequency f of this clock signal CL variable and adjusting it depending on the type of material, temperature, etc., it is possible to always maintain a constant relationship between the count value of the counter and the distance within the material.

The output lines F□ to F9 for each bit of the counter 8 are introduced into the central processing unit CPU as address designation lines.

Note that the output line F of the minimum bit LSB.

The reason why is not installed in the CPU is to set the content of the counter to 172, as will be described later.

The central processing unit [PU has a built-in microprogram unit, non-volatile memory, etc., and the counter output line F□~
When an address line is designated once by F9, l is added to the stored numerical value that is the contents of that address.

A signal E is introduced into the CPU as a request signal for this 1 addition.

Other address lines F1o/F□6 of the CPU are used to specify the inspection area, for example, FIO"FIO" is 01000.
If it is 00, 51 pots from the 51st place of the CPU to the 1.023I place correspond to the inspection area.

Next, the operation of the embodiment will be explained with reference to the explanatory diagram of FIG.

Determine a position that divides the space between the detectors 2A and 2B evenly.

, G1...Glo.

If the maximum value is 10, then the time difference in which the sound waves reach the detector when each position becomes the sound source is proportional to the distance difference between the two ends, so that it becomes as shown in the figure a.

If the contents of counter 8 are preset to 10,
At a location closer to detector 2A than the center position, signal A arrives before signal B and the counter operates as an up counter, and at a location closer to detector B than the center position, signal A arrives before signal B.
arrives before signal A and the counter operates as a down counter, so the contents of the counter are as shown in the figure.

Actually the output F of the least bit LSB of the counter.

Since the arithmetic processing of (XI/2) is essentially performed by deleting , the signal specifying the CPU address becomes as shown in C in the figure.

This numerical value is nothing but the positional coordinates of the material to be inspected.

In this way, the input A is input to the time difference calculation circuit section 3.

Immediately upon arrival of B, the counter 8 changes to the content corresponding to the sound source position, and 1 is added to the memory content of the CPU related to that sound source device.

By outputting the memory contents of the CPU after a predetermined load test, it is possible to know the frequency of occurrence for each sound source position.

According to this invention, the reversible counter 8 counts the tough lock pulses CL through the gate circuit 6 or 7,
Since the counted digital values are transferred in parallel to the address lines of the memory, there is no substantial time delay, and vibration phenomena that occur frequently and irregularly can be accurately measured and recorded without any detection errors. Alternatively, the load can be stopped before destroying the object.

Furthermore, complicated arithmetic processing using a program as in the past is unnecessary, and the burden on the computer in terms of both software and hardware is reduced.

Therefore, in addition to inspecting metal materials for defects before they are used, for example, water pipes of equipment that require a high level of safety, such as nuclear reactors, are always equipped with this equipment, and if a defect occurs during operation, it can be checked. From an economical perspective, it is also possible to widely use it in devices for early detection.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of this invention. FIG. 2 is an explanatory diagram of the operation of this embodiment. 1... material to be inspected, 2... detector, 3
...... Time difference calculation circuit section, 4... Arrival order determination circuit 5... Arrival time difference detection circuit, 6, 7.
...-AN age circuit, 8...counter.

Claims (1)

[Scope of utility model registration request] first and second detectors for detecting vibration phenomena, means for following the arrival order of input signals to the detectors, means for measuring the arrival time difference of the input signals to the detectors, and a reversible device with a preset. a counter; a first gate means for introducing a clock signal into an up-count terminal of the reversible counter by a time difference of arrival at the second detector when an input signal arrives at the first detector first; a second gate means for introducing a clock signal corresponding to the arrival time difference to the first detector into the down-count terminal of the reversible counter when the input means arrives at the second detector first; A CPU (Central Processing Unit) comprising means for presetting a predetermined value, a memory for storing the contents of the reversible counter and its frequency, and an output of the means for measuring the arrival time difference as an addition request signal of the memory. and a circuit means for introducing each bit output of the reversible counter in parallel as an address in the memory, and when a vibration phenomenon occurs between the first and second detectors, the vibration phenomenon occurs at the occurrence position. A device for measuring the position of a vibration source and its frequency of occurrence, wherein the reversible counter counts a value corresponding to the coordinate, and the frequency of occurrence and the coordinate data of the position of vibration are stored in the memory.