JPS62222161A - Flaw detector by means of plane wave - Google Patents

Abstract

PURPOSE:To effect accurate flaw detection, by, in a two-dimensional co-ordinate system in which is composed of condition of detection of echoes from a flaw and echo-detecting time, expressing a magnitude of the echo by luminance or color. CONSTITUTION:An angle variable probe 5 operated by outputs from angle- frequency controlling apparatus 10 and pulsor 6 is brought into contact with a surface of a specimen 1 and supersonic waves are irradiated onto it, plane waves are created and the waves propagate through the specimen 1. Upon finding a flaw F in the specimen 1, the wave W is reflected by the flaw F and comes back to the probe 5. The reflected wave f of the wave W is detected by the probe 5 is transmitted to a display apparatus 9a as luminance or color signal via amplifier 7, wave detector 8. On the other hand, incident angle thetat from the apparatus 10 and signal of time t from the pulsor 6 via a time- sweeping signal generating circuit 11 are introduced into the display apparatus 9a. And, in a two-dimensional co-ordinate system consisting of the angle thetat and the time (t), as a magnitude of echo (f) is expressed by luminance or color, accurate flaw detection becomes available.

Description

[Detailed description of the invention] [Field of application in the field of transportation] This invention is directed to plate waves (waves propagating in a thin plate-shaped elastic body).
The present invention relates to a plate wave flaw detection device that non-destructively measures defects in thin plates using .

[Conventional technology]

FIG. 5 is a block diagram showing a conventional plate wave flaw detection device. In the figure, (1) is the material to be tested, (5) is the variable angle probe, (2), [3), (4) the piezoelectric element constituting the variable angle probe (5), the movable shoe, The fixed knee, (6) is a pulser for electrically driving the piezoelectric element (2) of the variable angle probe (5), and (7) is the piezoelectric element (detected by the piezoelectric element (2) and converted into electricity. An amplifier that amplifies the signal, (8) is an amplifier (
7) is a detector that detects the output signal of the detector (9) is a detector that detects the output signal of the detector (8).
), F is a defect in the material to be inspected 1.

θi is the incident angle of the plate wave W, and θt is the refraction angle.

Next, the operation will be explained. The variable angle probe (5) consists of a fixed shoe (4), a movable shoe (3) and a piezoelectric element (2), the piezoelectric element (2) is glued to the movable tube (3), and the fixed shoe (4) and is acoustically coupled (for example, by infiltrating the contact surface with oil) so that it can rotate once.

The valve (6) generates pulses at regular intervals, applies high voltage pulses to the piezoelectric element (2), and vibrates at the natural frequency of the piezoelectric element (2). This vibration is transmitted as an ultrasonic wave through the movable shoe (3) to the fixed shoe (4). The fixed shoe (4) and the material to be tested (1) are acoustically coupled by a film of water or oil, so ultrasonic waves enter the material to be tested (1) from the fixed shoe (4). go. At this time, since the material to be inspected (1) and the fixing shoe (4) are generally different from each other, the ultrasonic waves are refracted at the boundary thereof. As shown in the figure, the angle of incidence is θi, the angle of refraction is θt, and the fixed shoe (4)
Assuming that the sound speed inside is C+ and the sound speed inside i-crosspiece (1) is C1, there is an arrow relationship.

In general, there are various modes of elastic waves that propagate through a plate.
For example, there are longitudinal waves, transverse waves, surface waves, plate waves (symmetrical S mode), and plate waves (obliquely symmetrical A mode).
speed of continuous sine wave waves, longitudinal waves, transverse waves 1
The phase velocity does not change depending on the frequency, but it does change with the plate wave. ) varies depending on the board material, board thickness, ultrasonic frequency, etc. In order to generate the plate wave (4) of the mode in the above method, the value of equation (1) must be equal to the phase velocity (Cp) of the plate wave (5) of that mode, that is, C! It must be done so that (2) is satisfied.

Therefore, by adjusting the incident angle (θi) of the movable shade (3) of the variable angle probe (5), equation (2) is realized.

Then, a plate wave of a predetermined mode (
4) occurs and propagates. If there is a defect (g) in the material to be tested (1), part of the plate wave (4) will be reflected and return toward the variable angle probe (5). The movable shoe (3) adjusts the incident angle (θ1) by the reverse operation of this wave, and a plate wave (5) in a mode corresponding to VC is detected. (7) is used to amplify the amplification and detector (
After being detected by 8), it is displayed on a display (9). A signal synchronized with the time when the piezoelectric element (2) is driven by the pulser (6) is given to the indicator (9) as a time sweep trigger signal, and is displayed as shown in FIG. In the figure, (
tl is the leakage input signal of the drive signal to the amplifier (7) side, (
f) is the reflected signal due to the defect (F'). σ) is the reflected signal (fl) returned by the defect (F) after driving the piezoelectric element (2), and is reflected by the piezoelectric element (2). In the time until detection, A indicates the magnitude of the signal reflected by the defect (Fl). From this display, it can be seen that the plate wave (
4) Defects that reflect (the presence or absence of a ladle 1 position, that is, time (T),
You can learn about Inugisaku. Presence or absence of defect (F) is 1
Based on the presence or absence of the reflected signal (f), the position of the defect (F) (c) and the propagation speed of the plate wave (a) of the mode used are known in advance.

From that value and time (calculated from Tl), the width of the defect (F) can be estimated on the premise that it has a correlation with the reflected signal (flag A of fl).

By the way, the reflection customization of the plate et (g) differs depending on the position and shape of the defect (F) in the thickness direction, and the relationship between the darkness differs depending on the mode. Furthermore, when a plate wave (5) in a certain mode hits a defect (F), the reflected wave is not reflected in the same mode by all the esulki, but is dispersedly converted into various modes. These matters are described in the Japanese Nondestructive Inspection Association magazine “Nondestructive Inspection J VOI, 22. A4-pI) 20
6-208 (Imoto: “Itanami Flaw Detection and 205 Subcommittee”),
The same magazine PP214-220 (Standing: “Prospects of plate wave flaw detection”)
) is described in detail.

Considering the above, it is not possible to accurately determine the presence or absence of defects, evaluate the sharpness A) of defects (F), and the position in the thickness direction for plate waves (4) in a specific mode. Can not.

In addition, in the above explanation, the phase velocity (Cp) of the plate wave (E) in the test material (1) is known, and the refraction angle (θ) is adjusted so as to satisfy Equation (2). However, in reality, the phase velocity (Cp) in the test material (1) is not known accurately, so while observing the echo from the edge of the test material (1), its magnitude can be determined. It is necessary to adjust the refraction angle (9) so that it is the maximum, which requires a lot of effort.

[Problem that the invention seeks to solve]

Conventional plate wave flaw detection equipment is configured as shown on μ, so it can only detect echoes from defects in one mode, making accurate evaluation impossible.

Also, to solve this problem.

It is conceivable to collect performance data in some modes, but there is a problem that adjustment when changing modes is very cumbersome and lacks practicality. Also, in the method of adjusting the refraction angle, it was not possible to observe the conversion from one mode to another.

This invention was made to solve the above-mentioned problems, and involves sequentially generating and detecting plate waves in various modes, and measuring the position and intensity of the reflected echo of the defect in each mode. The purpose of the present invention is to obtain a plate wave flaw detection device that can visually detect defects by integrating them, and accurately evaluate defects.

[Means for Solving Problem C] The plate wave flaw detection device according to the present invention is performed by changing the condition for detecting the occurrence of plate waves to #A, and some of the conditions are as follows.

The temporal rectification of the detected signal is displayed on another axis, that is, on a two-dimensional coordinate system, and the intensity of the detected signal is displayed in correspondence with the brightness or color. In other words, the ultrasonic wave is displayed on a thin plate. In a device that measures the position and size of the defect by displaying the reflected wave from the defect in the thin plate on a display, a measurement condition setting device and a command from the measurement condition setting device A vapulsar that generates a pulse signal to generate a plate wave in the variable probe in the measurement condition setting device and triggers the time sweep signal generation circuit, the output of the time sweep signal generation circuit, and the measurement condition setting device. Is it activated by the output of an amplifier that receives the other outputs and the detection signal of the variable angle probe as input, and a detector that uses the output of this amplifier as input? It consists of a display device.

[Operation] In this invention, when the angle/frequency I' control device and the variable angle probe operated by human power from the pulser are brought into direct contact with the material to be examined and ultrasonic waves are incident, plate waves are generated. The plate waves move through the material being tested. If there is a defect in the shell of the material to be inspected, a portion of this plate wave will be reflected and return to the variable angle probe again. Sent to this board. -The 10,000-meter display receives the angle/frequency PJII control device main device radiation angle (θt) signal, and the time (1) signal from the pulser via the time sweep signal generation circuit, and these six signals are displayed. For example, the luminance or color of a spotlight and t-θ are displayed as coordinates (orthogonal coordinates) on a device (a cathode ray tube).

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, (1) is the material to be tested, (5) is the variable angle probe installed on the surface of the material to be tested (1), and αO is the incident angle 01 of this variable angle probe (5) that is sequentially changed. At the same time, there is a means for primary changing the detection conditions Yll, which will be described later, that is, a measurement condition setting device!
It is tCL5. (6) C The pulser is driven by the variable angle probe (5) to generate a plate wave hv according to the command from the angle/frequency controller αO, and (7) is the defect detected by the variable angle probe (5). (F+ reflected signal (fl Y #! width amplifier, (8) is a detector that detects the output signal of amplifier (7), αD is a pulser (6) that drives variable angle probe (5) Time sweep signal generation circuit that generates a sawtooth wave in accordance with the timing, (9a) &j angular frequency control device αO
The coordinates of the first axis (horizontal axis) are determined by the output voltage corresponding to the incident angle θi, and the coordinates of the second axis (vertical axis) are determined by the output signal of the time sweep signal generation circuit α℃. In particular, the output signal of the detector (8) is used as a luminance modulation display. FIG. 2 is a display example diagram showing an example of the pattern σ) of the display (93). In the figure, a Yanagi-shaku lッ variable angle probe (
5) Wandering material (1) when ultrasonic waves enter the material to be tested (1)
The refraction angle θt at the side (see Fig. 5) ranges from 0'' to 91f.

First, the angle/frequency controller α (hK) controls the variable angle probe (5) and sets θt=Q. Next, the angle/frequency controller αO issues a command to the pulser (6). This generates a pulse, which causes the variable angle probe (5) to generate a plate wave W in the material to be tested (1). A trigger signal is given to the circuit α, and a voltage signal 1 proportional to time is generated from the time sweep signal generation circuit αD, and is given to the display (9a), and a bright spot appears on the display (9a). moves along the vertical axis as indicated by A in the figure.The brightness of the bright spot is determined by the generated plate wave propagating through the material to be inspected (1), reflected by the defect (n), and changing the brightness at a variable angle. Detected by the probe (5),
The signal is amplified by an amplifier (7) and detected by a detector (8), and then modulated. Therefore, if the echo from the defect iFl is large, the display will be bright (displayed), and if the echo is small, the display will be dark (displayed).

When this time sweep is completed, the angle/frequency controller αd is changed to θ
Set tY1° and perform 7 similar operations. When the time sweep at θ1=1° is completed, θt is changed, and the same operation is carried out. This operation is repeated in sequence until θt=9[]', and then θt = Q state is returned, and the above operation is repeated. As a result, for example, the specimen material (1
) is a steel plate with a thickness of 2.3 mm (spa) and there is a hole-shaped defect that penetrates the top and bottom, fst in Figure 2.

An image like fs1+fkl is obtained. These are the reproductions of the same defect fFl among the reflected echoes when the plate waves of S mode, SI mode °, and A1 mode are applied to the defect (8).Each mode is about 2f, sf, sf, respectively. de1
The conditions for occurrence and detection are in place, but in reality, it is not a point at J5 in the diagram, but spreads out before and after it.

From this display result, it can be seen that the plate wave W of each mode has the same defect (F
'l can be seen how it is reflected.

FIG. 6 shows another defect (F) of the display device (9a) according to the present invention.
It is a display example figure showing +. In the figure fS! l fs1
1f/J is an image in the same plate wave (b) mode as in Figure 2, but this figure is one of the examples where the defect does not pass through the upper and lower directions, and the image of fs is clearly visible. This shows that depending on the position of the thickness of the defect CF+, it is difficult to obtain fs, and the value of fA varies depending on the position. Therefore, if these images are obtained in accordance with the defect, Defects can be classified by looking at 'Y'.

FIG. 4 is a block diagram showing another embodiment of the fourth ['a+-z,:σ) invention]; In the figure, (11, (5a) to (to)
and seedlings.

fFl, ridge) shows the same or equivalent part as the example in Fig. 1, but it is separated into a variable angle probe (5a) and a variable angle detection probe (5b), and the generation is only one. The mode was selected, and the detection was carried out by sequentially changing the refraction angle (θt) (Fig. (The classification and evaluation of j will become more accurate.

Further, in the above embodiment, a mechanical variable angle probe (5a)
, Change the conditions for plate wave generation and plate wave detection in (5h) Y;
L 5 VCgl However, an array type probe in which minute ultrasonic elements are arranged may also be used.

By doing so, there are advantages such as rapid changes in conditions and the ability to independently change conditions for generation and detection using one probe, and the effect of the present invention can be greater than t.

Further, although the coordinate system and the orthogonal coordinate system are shown, the effects of the present invention will not be hindered in any way even if a different coordinate system is used. For example, by using a polar coordinate system and determining the angular direction, the aforementioned θt, or θ1IK-, the physical correspondence with the variable angle probe (5) can be established.

Furthermore, in the above, O is used as a variable for plate wave generation and detection conditions.
Instead of tχ, the phase velocity (Cp) and Y may be used (or, if an array type probe (5) is used, the phase difference (or time difference) between the elements may be used).

Furthermore, in the above embodiment, the magnitude of the echo, that is, the reflected wave (f
It is also possible to change the brightness of the display by pressing l, 4, or 1.

Furthermore, in the above embodiment, one of the coordinate axes was shown to be swept over time, but for each mode, the group velocity (distance) is determined from the actual plate wave propagation velocity and time. You can also sweep it.

In addition, in the above embodiment, the conditions for generating plate waves are changed at every 1° angle, but it may be determined as many times as necessary, or may be determined selectively, not just at regular intervals. Needless to say.

〔Effect of the invention〕

As described above, according to the present invention, the conditions for detecting the occurrence or detection of plate waves are sequentially changed to obtain echoes from defects.
The two-dimensional coordinate system consists of the detection condition (Ol) and the echo detection time [tl], and the size of the echo is determined by brightness or color, so it is possible to classify defects and ensure accurate flaw detection. If you can get something that is possible, it will be effective.

[Brief explanation of drawings]

FIG. 1 shows a plate wave flaw detector It? according to an embodiment of the present invention.
The block diagram shown in FIG. 2 is a display example diagram according to the present invention,
FIG. 3 is a diagram showing another display example according to the present invention, and FIG. 4 1 is a block diagram showing another embodiment of the present invention. Fig. 5 is a block diagram showing a conventional plate wave flaw detection device;
The figure shows an example of a conventional display.
1 is an explanatory diagram showing seven dongs of a plate wave in a broad sense. In the figure, (1) is the material to be tested, (5) is the variable probe, (
6) (Yuparsa, (7) is an amplifier, (8) is a detector, (
9a) and (9b) are display devices, αO is an angle/frequency control device, ■ is a time sweep signal generation circuit, and a mechanical measurement condition setting device. In each figure, the same reference numerals indicate the same or corresponding parts Z.

Claims (4)

[Claims] (1) In a device that measures the position and size of the defect by introducing ultrasonic waves into a thin plate and displaying reflected waves from defects in the thin plate on a display, the measurement condition setting device and the measurement A pulser that generates a pulse signal according to a command from the condition setting device to generate a plate wave in the variable probe in the measurement condition setting device and triggers the time sweep signal generation circuit, and the output of the time sweep signal generation circuit. and an amplifier that receives the other outputs of the measurement condition setting device and the detection signal of the variable angle probe as inputs, and a display that operates based on the output of a wave detector that receives the output of this amplifier as input. A plate wave flaw detection device characterized by being configured as follows. (2) The plate wave flaw detection apparatus according to claim 1, wherein the variable probe uses generation and detection of ultrasonic waves in combination, or has an independent configuration. (3) The plate wave flaw detection apparatus according to claim 1, wherein the display device is capable of displaying the position and size of the defect using orthogonal coordinates or polar coordinates. (4) The plate wave flaw detection apparatus according to claim 1, wherein the variable probe is a mechanical variable probe or an array type probe.