JPS6282350A - Ultrasonic flaw detecting device - Google Patents

Abstract

PURPOSE:To grasp accurately the quantity of creep damage without being affected by variation in plate thickness due to corrosion, etc., by detecting an acoustic wave which is scattered and reflected by an extremely fine defect in a material as a noise and grasping the progress state of a creep. CONSTITUTION:When an ultrasonic wave signal (n) is inputted to the material 1 to be inspected, a part of the signal (n) is scattered and reflected by its internal extremely fine defect 14 and the remainder is reflected by the bottom surface 15 to pass through a probe 2 and sent to a gate circuit 4 through an ultrasonic wave transmitter receiver 3. The circuit 4 extracts a signal (g) received in a gate interval (t) among respective signals, i.e. a noise component and sends it to an A/D converter 8. A computing element 9 analyzes the frequency of the noise waveform digitized by the converter 8. The digital waveform which is sampled at the same timing when the object material 1 is in a sound state and in various creep damage states and frequency-analyzed is stored as a sample in a memory device 10, and a comparator 12 displays a sample similar to a selected and detected waveform and the detected waveform on a monitor 13 as an image; and the degree of the similarity is observed to grasp the quantity of creep damage numerically.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an apparatus for non-destructively inspecting material defects in various industrial plant equipment and structures using ultrasonic waves, particularly for detecting creep inside metal materials. This invention relates to an ultrasonic flaw detection device that can accurately detect damage.

"Conventional technology" In order to improve the safety, reliability, and economic efficiency of various industrial plants, non-destructive inspection of the equipment and structures that make up the plants in operation plays an important role in predicting their remaining life. Conventional ultrasonic flaw detection equipment, as shown in Figures 3 to 5, injects ultrasonic waves C from a probe a in the thickness direction of the material to be inspected, and reflects them from the bottom surface d of the material to be inspected. echo e,
The time difference 9 and amplitude difference in which f, (e is the first echo, f is the second echo) appear are measured using the measuring device i, and the same inspection is performed on the new material before plant operation. Using the time difference and amplitude difference data 9' and h' obtained in They were monitoring the progress of the creep and checking the safety of equipment. Note that in FIG. 4, the symbol j indicates an electrical signal of an incident transmission wave.

[Problems to be Solved by the Invention] However, according to the above-mentioned measurement method, as shown in Fig. 5, if corrosion or pitting occurs on the bottom surface d of the strained material to be tested and the plate thickness becomes uneven, the effect will be appears strongly in the echoes e and f, making it difficult to measure changes in sound speed and attenuation rate, that is, to estimate the amount of creep damage.

[Means for Solving the Problems] The present invention was made to solve the above-mentioned problems, and its purpose is to provide an ultrasonic transmitter/receiver that transmits and receives ultrasonic waves through a probe. , a gate circuit that extracts some of the electrical signals sent from the ultrasonic transceiver, an A/D converter that converts the electrical signals sent from the gate circuit into digital signals, and the A/D converter that converts the electrical signals sent from the gate circuit into digital signals. an arithmetic unit that frequency-analyzes the digital signal sent from the /D converter; a memory unit that records digital waveforms corresponding to various creep regions; and a digital waveform sent from the arithmetic unit and the memory unit. Equipped with a comparator that compares the digital waveforms extracted from the
This is accomplished by using an ultrasonic flaw detector that sets the ghoul spacing of the gate circuit prior to the time when the first echo reflected from the material to be inspected is received.

[Function] Sound waves scattered and reflected by minute defects inside the material are detected as noise, and the progress of creep is determined from the relationship with the amount of creep damage, so there is no possibility of the material being adversely affected by material corrosion, uneven thickness, etc. There is no.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure and FIG. 2 show one embodiment of the present invention, and in the figure,
1 is a material to be inspected, 2 is a probe, 3 is an ultrasonic transceiver, and 4 is an electric signal of an amplified reflected wave sent from the ultrasonic transceiver 3 at a predetermined timing and for a predetermined elapsed time, i.e. When the first echo electric signal @m (see Figure 2) appears, the noise sampling gate circuit 8 has a gate interval between time 6, which precedes time 5 by t+at, and time 7, which precedes by At. This is an A/D converter that converts the electric signal extracted by the gate circuit 4 into a digital signal.The number of 4 non-pulling points is set to 2048 in order to digitize the noise waveform, which is a group of many signals with small amplitude, with good viscosity. I try to get as much as possible. 9 analyzes the frequency of the digitized waveform and sends the results to a memory 10 and a comparator 12
A calculator 13 takes out the already stored digital waveform from the memory 10 and sends it to the comparator 12. A monitor 13 displays the comparison result as an image on a CRT screen.

Next, the operation of this device will be explained. When an ultrasonic signal n is incident on the inspected material 1 in which an internal microdefect 14 (hair crack or cavity, etc.) exists, this signal @n
A part of it is scattered and reflected by the internal micro defects 14, and the rest is reflected by the bottom surface 15 of the food to be tested, and these are reflected by the probe 2.
The signal is converted into an electrical signal and sent to the ultrasonic transceiver 3. As shown in FIG. 2, the ultrasonic transmitter/receiver 3 converts the scattered and reflected sound wave p into an electrical signal q observed as noise, and the sound wave r reflected at the bottom surface 15 into an electrical signal q observed as an echo. The signals m and s are each amplified and sent to the gate circuit 4.

The gate circuit 4 extracts only the iM number q, that is, the noise component, which is received during the gate interval t, from among the received signals @q, m, and s, and sends it to the A/D converter 8. A/D converter 8
has a sampling interval of 0.1 in order to accurately digitize a noise signal consisting of a group of small waveforms with small amplitudes.
2048 points are digitized at ~ins, and the digitized noise waveform is sent to the computing unit 9, which analyzes the frequency of the received noise.

On the other hand, the material to be inspected 1 is stored in the storage device 10 in a healthy state (new!
1) and digital waveforms taken at the same timing and subjected to frequency analysis during various creep damage states are stored as samples, and the comparator 12 compares these samples with the detected waveforms one by one for detection. A sample that approximates the waveform is selected, this sample and the detected waveform are displayed as images on the monitor 13, and the inspection i observes the degree of similarity of the waveforms to quantitatively grasp the amount of creep damage on the inspected material 1. Note that the comparator 12 is provided with an alarm device (not shown), which issues an alarm when the detected waveform deviates from the waveform defined by the "threshold".

It should be noted that the present invention is not limited only to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of Explanation] As described above, the present invention exhibits the following excellent effects.

(+) Since sound waves scattered and reflected by minute defects inside the material are detected as noise, the amount of creep damage can be accurately determined without being affected by changes in plate thickness due to corrosion, etc.

(ii) For the same reason as in item (1), this device can be widely applied to the inspection of thick-walled materials.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a block diagram of this device, FIG. 2 is an explanatory diagram showing the principle of measurement by this device, and FIGS. 3 to 5 are conventional FIG. 2 is an explanatory diagram of the measurement principle of the device. In the figure, 1 is the material to be inspected, 2 is the probe, 3 is the ultrasonic transceiver, 4 is the gate circuit, 8 is the A/D converter, 9 is the arithmetic unit, 1
0 indicates a memory, and 12 indicates a comparator.

Claims (1)

[Claims] 1) An ultrasonic transceiver that transmits and receives ultrasonic waves via a probe, a gate circuit that extracts some of the electrical signals from the electrical signals sent from the ultrasonic transceiver, and from the gate circuit. An A/D converter that converts the sent electrical signal into a digital signal, an arithmetic unit that frequency-analyzes the digital signal sent from the A/D converter, and digital waveforms corresponding to various creep amounts are stored. A comparator that compares the digital waveform sent from the arithmetic unit and the digital waveform taken out from the memory, and the gate interval of the gate circuit is determined by the first echo reflected from the material to be inspected. An ultrasonic flaw detection device characterized in that the setting is made in advance of the time when the item is received.