JPS58223059A - Ultrasonic flaw detector - Google Patents

Abstract

PURPOSE:To detect the size and shape of a defect at a high accuracy by the addition of a reflected wave signal corresponding to the sum of the distance to a microscopic area from transmission vibrators and the distance to the vibrators receiving reflected waves from the microscopic area. CONSTITUTION:Any vibrator 102-n is selected with a selection circuit 103 to apply a pulse thereto from a high voltage pulse generation circuit 106, an ultrasonic beam in an object 112 to be inspected is transmitted in a conical shape and reflected waves from a defect 116 received with other vibrators 102-1. A reflected wave signal is amplified sequentially with an amplification circuit 110 through a scanner 107 and memorized into a memory circuit 111. In a signal treatment circuit 113, the sum is determined between the distance to the microscropic area A set as desired from the vibrator 102-n and the distance to vibrators 102-n... from the microscopic area A and relfected wave signal within a gate period G corresponding thereto are extracted from a memory circuit 111 to be added. The microscopic area A is set sequentially for the entire flaw detection range and a similar signal processing is done to prepare an image signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic flaw detection device for piping, etc. of nuclear power generation equipment.

[Technical background of the invention and its problems]

Generally, piping and reactor pressure vessels of nuclear power generation equipment are subjected to ultrasonic flaw detection during manufacturing or periodic inspection to ensure reliability.

1 to 4 show conventional ultrasonic flaw detection equipment used in this type of ultrasonic flaw detection, and numeral 1 in the figures is an ultrasonic probe. The ultrasonic probe 1 is moved by the scanning mechanism 2 in mutually orthogonal X and Y directions and scanned along a predetermined constant strain path. As shown in FIG. 2, the ultrasonic probe 1 is configured to emit an ultrasonic beam obliquely into the object 3 to be inspected and to receive the reflected wave.

Therefore, when there is a defect 4 in the object to be inspected 3, the ultrasonic probe 1 has a reflected wave signal SI from the front surface of the object to be inspected 3 and a reflected wave signal S2 from the back surface as shown in FIG. The reflected wave signal S3 from the defect 4 is received, and the output of the ultrasonic probe 1 is sent to the signal processing circuit 6 via the flaw detector 5 (Fig. ). Therefore, the signal processing circuit 6 creates an image signal of the inside of the object to be inspected 3 based on the output of the ultrasonic probe 1 and displays the defect 4 on the display 11.
can be displayed as an image.

Note that 8 in the figure is a control circuit for controlling the scanning mechanism 2.

In the conventional ultrasonic flaw detection device configured as described above, as shown in FIG. The reflected wave signal from the defect 4 is received from the moment the ultrasonic beam scans until the trailing edge of the defect 4 leaves the other end of the defect 4. For this reason, the size of the defect 4 is magnified and detected as shown by the broken line 4' in FIG. 4, resulting in a problem that a high degree of detection accuracy cannot be obtained.

Also, if there are multiple horizontally adjacent defects,
There was also a risk that these defects would be detected as a single connected defect. Therefore, one possible way to solve this problem is to make the ultrasonic beam thinner, but there is a limit to how thin the ultrasonic beam can be made, so the above-mentioned device is used to improve the detection accuracy. naturally had its limits.

Therefore, in order to solve such problems, a signal processing method called an aperture synthesis method has been considered. This is the fifth
As shown in the figure, an ultrasonic beam that spreads in a conical or fan shape from the ultrasonic probe 1 toward the inside of the object to be inspected 12 is sent to the measurement point P.
+-Py and its reflected wave signal is received via the same probe 1. At this time, if there is a defect 13 in the object to be inspected 12, as shown in FIG. A wave signal SS is transmitted. The return position of the reflected wave signal S is the measurement point P1-P
? It changes depending on. Therefore, any minute area 14 is set inside the object 12 to be inspected, and the distance 17-1 from the measurement points P1-Pq to the minute area 14 is determined as shown in FIG.
q is calculated, and the distance tl to t? is calculated from among the reflected wave signals corresponding to the reflected waves received at the measurement points P1 to Py. By extracting the reflected wave signals corresponding to the reflected wave signals, adding these signals, and evaluating the size, it is determined whether the minute area 14 is the reflection source (i.e., the defect 13) of the reflected wave signal. can do. Then, by changing the position of the minute region 14, similar signal processing can be performed on the entire interior of the object to be inspected 12, and thereby the object to be inspected 1
2 cross-sectional images can be detected. The cross-sectional image of the object to be inspected 12 obtained in this way has a much better resolution than the cross-sectional image obtained by a conventional flaw detection method that does not use the aperture synthesis method. Therefore, the size of a horizontal defect can be detected with high precision, and a plurality of horizontally adjacent defects can also be detected separately.

However, such aperture synthesis method has the following problems. In other words, K for obtaining excellent resolution is the measurement point P L
It is better to widen the range of ``'-P'', that is, the aperture.

However, even if the aperture is wide, there is a defect 1 at the measurement point P L-P 7.
Detection is impossible unless three reflected waves from the same point are received redundantly. That is, it is necessary that the reflected waves from the same point of the defect 13 be diffused as shown in FIG. 8(4) or (B). However, the shape of defect 13 is as shown in Fig. 8 (C
) or ■), the reflected waves from both ends of the missing vinegar 3 are well diffused, but the parts other than both ends reflect specularly with respect to the incident direction of the ultrasonic beam, so the reflected waves are not diffused. Almost no reflected waves can be obtained. Therefore, Fig. 8(C)
, Q)) In the image of a linear defect, only two points at both ends appear as shown in FIG. 9, and there was a problem that it was impossible to distinguish it from a point defect.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to detect defects in the inspected body with high precision,
An object of the present invention is to provide an ultrasonic flaw detection device that can clearly distinguish between linear defects and point defects.

[Summary of the invention]

The ultrasonic flaw detection device according to the present invention places an ultrasonic probe on an object to be inspected, and uses one transducer arbitrarily selected from among a plurality of linearly arranged transducers to be inspected. An ultrasound beam that spreads into the body in a conical or fan shape is emitted, the reflected waves are received by each transducer, and the reflected wave signals sent out from each transducer are stored in a memory circuit, and the ultrasound beam is The storage circuit stores a reflected wave signal corresponding to the sum of the distance from the vibrator that transmitted the signal to a minute area arbitrarily set within the body to be inspected, and the distance from that minute area to each vibrator that received the reflected wave. It is configured to extract the images and add them to create an image signal.

Therefore, only the reflected wave signals when there is a defect in a minute area are added, and the size and shape of the defect/□ defect can be detected with high precision.

[Embodiments of the invention]

FIG. 10 shows a schematic configuration of an ultrasonic flaw detection device, and 101 in the figure is an array type ultrasonic probe. This probe 1
01 is a plurality of transducers 10L arranged in a straight line,
702. It is composed of... and each oscillator 1θ2−+ HI 02−2 .

. . . are each switching contact 104 of the selection circuit 103. .

104-ffi+... and is connected to the high voltage pulse generation circuit 106 via the selection contact 105. In addition, each transducer 10L+ + 102-tr... is connected to each switching contact 10L, , 10L, of the scanner 107.
, ... and connected to the amplifier circuit 110 via the selection contact 109, and each vibrator 102-+ + 102-*
+... are configured to sequentially amplify the reflected wave signals sent out and supply them to the storage circuit 11. A signal processing circuit 113 that creates an image signal inside the object to be inspected 112 is connected to the memory circuit 111, and an image display 114 that displays the state inside the object to be inspected 112 as an image is connected to this signal processing circuit 113. ing. In the figure, reference numeral 115 is a control circuit for controlling the selection circuit 103, the high voltage/4' pulse generation circuit 106, the bias/yana 107, and the memory circuit 11.

Next, the operation of this embodiment will be explained.

First, the selection circuit 103 selects an arbitrary oscillator i o :z-
n is selected and a high voltage pulse is applied to the transducer 1o2-n from the high-voltage pulse generation circuit 106. A sound beam is transmitted in a conical or fan-like manner. .

Now, there is a linear defect 116 in the object to be inspected 112, and the ultrasonic beam emitted from the sensor 102-n is directed to this defect 1.
16, and the reflected wave is transmitted to each other vibrator 102-1.
．． 102-2 1... is received by...

Note that since there is only one amplifier circuit 110, it emits ultrasound beams equal to the number of transducers. The reflected wave signal sent out from the vibrator is then sequentially sent to an amplifier circuit 11 via a scanner 107.
0 and stored in the storage circuit 111. At this time, the reflected wave signals sent out from the vibrators 102-* + 102-t +... include reflected waves corresponding to reflected waves a and b that are diffused from both ends of the linear defect 1160, as shown in FIG. It includes signals S, , Sb, and a reflected wave signal S8 corresponding to a reflected wave C that is specularly reflected at other parts. The signal processing circuit 113 processes the signal stored in the storage circuit 111 as follows. That is, an arbitrary minute area A is set in the object to be inspected 112 as shown in FIG. Vibrator 10
2-I Find the sum with the distance to H102-1+"', extract the reflected wave signal within the dart period G corresponding to this sum using the storage circuit 111, and add them. This dart period G is , from the time when the ultrasonic beam is emitted from the transducer 102-n, it is reflected in the minute area A, and the reflected wave is transmitted to each transducer 102-1+1172t,!...
・corresponds to the time up to the time when the wave was received at 1
, Therefore, if there is a defect 116 in this minute area A,
As shown in FIG. 11, a reflected wave signal S8 corresponding to the reflected wave from the defect 116 exists within the dirt period G. Since all of these reflected wave signals Sa... are added, the level of the added signal becomes high.

Since the ultrasound beam is still spread out in a conical or fan shape, the focal point is the transmission position (point) of the ultrasound beam and the reception position (point) of the reflected wave, as shown in Figure 11. If a reflection point exists on one ellipse, then the reflected wave signal at that time exists within the dirt period G. Therefore, if there are other defects or the back side of the object to be inspected 112 on the same ellipse, a reflected wave signal due to the reflected wave from them will exist within the dirt period G. Since they each have different elliptic constants (focal points and distances), they do not intersect at a single point except in the microscopic region A. Therefore, if there is no defect in the microscopic region A, the reflected wave signals from other parts f-) Even if it exists within period G, the level of the addition signal is low.

Therefore, by cutting the signal level obtained by adding the reflected wave signals within the dirt period G to a predetermined level, it is possible to remove the noise caused by the reflected waves in areas other than the minute area A. Then, by sequentially setting minute areas A for the entire flaw detection range within the inspection object 112 and performing the above signal processing for each minute area, the position of the defect existing within the flaw detection range,
1 capable of detecting the shape or the shape of the back surface of the object to be inspected 112 with high precision and creating an image signal thereof;
The image display 114 displays an image of the state inside the object to be inspected 112 based on the output of the signal processing circuit 113.

Note that in the above, one arbitrarily selected transducer 102-n emits an ultrasonic beam, and the reflected waves are transmitted to each transducer 102-n.
-, , 102-, , ... and perform predetermined signal processing on the reflected wave signals, but the reflected wave signals obtained by sequentially switching the transmitting transducers It is also possible to perform similar signal processing including the following.

In addition, by selecting multiple transducers for transmission and delaying the high-voltage pulses applied to each transducer by a small amount of time, the ultrasonic beams emitted from those transducers are focused, and then Alternatively, if the ultrasonic beam is diffused in a fan shape, the transmission energy of the ultrasonic beam can be increased.

〔Effect of the invention〕

As detailed above, the ultrasonic flaw detection device according to the present invention includes:
An ultrasonic probe is placed on the object to be inspected, and an ultrasonic beam that spreads in a conical or fan shape is emitted from one transducer arbitrarily selected from a plurality of transducers arranged in a straight line. , the reflected waves are received by each transducer, and the reflected wave signals sent out from each transducer are stored in a memory circuit. The storage circuit extracts a reflected wave signal corresponding to the sum of the distance to the minute area and the distance from the minute area to each vibrator that received the reflected wave, and adds them to create an image signal. This makes it possible to detect defects within the object to be inspected with high precision, and has excellent features such as being able to distinguish between linear defects and point defects, and clearly detecting multiple adjacent defects. You can get the same effect.

[Brief explanation of the drawing]

Figures 1 to 4 show conventional examples, where Figure 1 is a schematic configuration diagram, Figure 2 is a diagram showing the transmission direction of the ultrasonic beam,
Figure 3 is a waveform diagram of the reflected wave signal sent out from the ultrasonic probe, Figure 4 is a diagram showing defects and their detection status, and Figures 5 to 9 show the background technology using the aperture synthesis method. Fig. 5 shows the defect and its detection state, Fig. 6 shows the waveform of the reflected wave signal sent by the ultrasonic probe, and Fig. 7 shows the positional relationship between the defect and the measurement point. Figures 8 (4) to 8) are diagrams showing the relationship between the shape of the defect and the diffusion state of reflected waves.
The figure shows an image of a linear defect, Figures 10 and 11 show an embodiment of the present invention, Figure 10 is a schematic diagram, and Figure 11 is a diagram showing defects and their detection status. be. 101...Array type ultrasonic flaw detection device, 1θ2-1゜1
0L,..., 102-nme... Camera, 1
11... Memory circuit, 113... Signal processing circuit, 11
4... Image display device, 116... Linear defect. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Leap (A) (B) 3

Claims (1)

[Claims] An ultrasonic beam that spreads in a conical or fan shape is emitted from one randomly selected transducer out of multiple transducers arranged in a straight line, and the reflected waves are received by each transducer. An ultrasonic probe that transmits an ultrasonic beam, a storage circuit that stores reflected wave signals sent out from each transducer, and an α distance and a A signal processing circuit that extracts a reflected wave signal corresponding to the sum of the distances from the minute area to each vibrator that received the reflected wave from the storage circuit and adds them to create an image signal; An ultrasonic flaw detection device comprising: an image display device that displays an image of the internal state of a body to be inspected based on the output of a circuit.