JPS61225647A - Ultrasonic flaw detection - Google Patents

Abstract

PURPOSE:To achieve a higher accuracy, by making the selection of a group of vibrators for operating an array type probe and the selection of the angle of deflection in an ultrasonic wave medium from the preset incident point of an ultrasonic wave into material to be inspected and a geometric positional relationship between the refraction angle of the ultrasonic wave at the point and the probe. CONSTITUTION:In an ultrasonic wave transmitter 10, (n) units of transmitters are selected by a trigger signal from a transmission delay setter 11 to send transmission pulses to corresponding ultrasonic vibrators 9 and ultrasonic waves are transmitted from the vibrators 9 in response thereto. On the other hand, the signals detected with the vibrators 9 are amplified 12 to be inputted into corresponding A/D converters 13. Then,a signal controller 15 selects a group of vibrators adapted to receive and transmit ultrasonic waves for a reception delay setter 14 and a setter 11 and applies a timing of outputting a trigger signal according to directions of transmitting and receiving ultrasonic beams and focal length as preset. The output of a converter 13 is memorized 16 to be inputted into a signal processor 17 and the direction of sweeping images for B scope display is determined from the angle of deflection at the preset time of transmitting and receiving ultrasonic waves to be displayed 18.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ultrasonic flaw detection method for detecting defects inside a test material such as a metal material or a non-metal material using an electronic sector scanning type ultrasonic flaw detection device. .

[Technical backbone of the invention and its problems] The inside of metallic or non-metallic materials? 113! As a method for this, an ultrasonic flaw detection device using ultrasonic waves has been commonly used. The ultrasonic flaw detection equipment used in such ultrasonic flaw detection methods uses an array type probe 1 consisting of a plurality of transducers for transmitting and receiving ultrasonic waves, as shown in Fig. 6. It is equipped with a transport structure that electronically controls ultrasonic wave transmission and reception timing. This type of flaw detection method is generally called the electronic scanning method, and as shown in Fig. 6(a), this electronic scanning method involves transmitting an ultrasonic beam 2 while sequentially switching a plurality of transducer groups for transmitting and receiving ultrasonic waves. A linear scanning method in which the specimen 3 is scanned in a straight line, and Fig. 6 (C
), the ultrasonic beam 2 is transmitted to the specimen 3 while sequentially changing the timing of ultrasonic wave transmission and reception by multiple transducer groups.
There is a sector scanning method that scans in a fan shape inside the . The defects 4 in the test material 3 are shown in Fig. 6 (b).
) and cathode ray tube (CRT) as shown in Figure 6(d).
) 5 is displayed as a defect image 6 on the B scope.

Although FIG. 6 shows a general direct contact method in which the array type probe 1 is brought into direct contact with the surface of the test material 3, other methods such as the water immersion method or the thin-coat flaw detection method may also be used. The present invention is also applied to a flaw detection method using an ultrasonic propagation medium between the mold probe 1 and the specimen 3.

On the other hand, in the above flaw detection method, as shown in Figure 7,
Ultrasonic beam r! The ultrasonic beam passing through the boundary 7 between media ■ and ■ with different speeds of sound is refracted at the boundary 7 according to Snell's law. At this time, the incident angle α and the refraction angle β of the ultrasonic beam 2 with respect to the normal to the boundary 7 are There is a relationship of 7 between the sound speed C1 of the medium and the sound SINμ)-C1 speed C2 of the medium □Nψ)-, and the incidence 5
This shows that there is no linear relationship between the angle α and the refraction angle β. Therefore, as shown in FIG.
When ultrasonic flaw detection is performed using the sector scanning method through the Is material 8 between the
As the deflection angle of the ultrasonic beam increases, the refraction at the boundary 7 increases, and the propagation path deviates from a straight line. Therefore, if an image display position signal is created simply by the deflection angle of the ultrasound beam and the ultrasound beam propagation time, as in the direct contact method, the actual ultrasound beam propagation path and the position on the image display will be 1 Because it does not correspond to one-to-one, errors occur in positioning defects, etc.? ! There was a problem that required rough image correction.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and is particularly useful when performing ultrasonic flaw detection using the sector electronic scanning method via a medium between an array type probe and a test material. Accurately detects information inside the specimen material without performing extensive image processing.
An object of the present invention is to provide an ultrasonic flaw detection method that allows the location of defects inside a material to be inspected to be determined with high precision.

[Standard type of the invention] In order to achieve the above object, the ultrasonic flaw detection method according to the present invention involves selecting an ultrasonic transducer for operating an array type probe and selecting an ultrasonic beam deflection angle within the ultrasonic IIL quality. and,
This is determined from the preset geometric positional relationship between the ultrasonic beam incidence point on the specimen, the refraction angle of the ultrasound beam, and the array type probe, and regardless of the deflection angle of the ultrasound beam, the It is characterized by performing sector electronic scanning with the ultrasonic beam incident point on the material as approximately one point.

[Embodiment of the Invention] An embodiment of the present invention will be described in detail below based on the drawings.

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

The array type probe 1 is made up of n ultrasonic transducers 9 arranged in parallel. These ultrasonic transducers 9 are each coupled to n ultrasonic transmitters 10 that generate transmission pulses, and these ultrasonic transmitters 10 are activated by a transmission pulse generation trigger signal from a transmission delay setting device 11. All or several transmitters are selected to send transmission pulses to their corresponding ultrasonic transducers 9, and in response to this, the ultrasonic transducers 9 are configured to transmit ultrasonic waves. .

On the other hand, the ultrasonic transducer 9 has reversibility and can also generate electrical signals in response to pressure changes. In this way, since the ultrasonic transducers 9 also have a transmitter function, the received signals detected by each ultrasonic transducer 9 are amplified by the corresponding n ultrasonic receivers 12. After that, the corresponding n A/D! The signal is input to the converter 13.

This A/D converter 13 converts the received ultrasonic signal into digital data at high speed, and can faithfully convert the received waveform into a digital signal. Further, a trigger signal for starting digital conversion of the received signal is supplied to the A/D converter 13 from a reception delay setter 14, respectively. All or some of the n A/D converters 13 that receive this trigger signal convert the ultrasonic reception waveform into a digital signal waveform in synchronization with the input time of the trigger signal.

The signal controller 15 selects a transducer group involved in ultrasonic reception and a transducer group involved in transmission for the reception delay setting device 14 and the transmission delay setting device 11, and transmits a preset ultrasonic beam. and provides timing for outputting a trigger signal according to the reception direction and focal length.

Further, the outputs of each A/D converter 13 are waveform-added and stored in an addition memory 16. That is, the A/D converter 13
The digital waveform of the ultrasonic reception signal once held is digitally added to the reception signal of each ultrasonic wave and the transducer 9 at the same time when the digital signal waveform was converted, and then stored. These operations are controlled by a signal controller 15.

The added received waveform in the processing memory 16 is sent to the signal processor 17.
is input.

The signal processor 17 determines the direction of the image sweep on the B scope display based on the preset deflection angle of the ultrasound main beam during ultrasound transmission and reception, and
It is output to the scope display 18. Further, the signal processor 17 applies brightness modulation to the image signal according to the magnitude of the received waveform.

This brightness modulation signal is obtained by attaching a signal discrimination level set by the signal processor 17 to the waveform obtained by detecting the fraudulently received waveform from the addition memory 16, and then adding a signal discrimination level set in the signal processor 17 to the waveform, and converting the signal according to the size of the waveform exceeding this signal discrimination level. It is produced within the processor 17.

In this manner, the ultrasonic detection apparatus shown in FIG. 1 repeatedly performs the above-described operations each time the ultrasonic transducer for transmission and reception is selected or changed, and the main beam direction is changed.

Next, the operation of the ultrasonic probe shown in FIG. 1 will be explained. That is, the ultrasonic flaw detection method according to this embodiment will be explained with reference to FIGS. 2 and 5.

As shown in FIG. 2, a case will be explained in which sector electronic scanning is performed via the medium 8 so that the ultrasonic emission surface of the array type probe 1 and the surface of the specimen 3 are parallel to each other at a distance of fi. do. That is, when a group of - ultrasonic transducers adjacent to an arbitrary ultrasonic transducer 9 (1) in the array probe 1 emits ultrasound at an ultrasound beam deflection angle θ, the center of the ultrasound beam The axis 2 is located at the boundary 7 between the ultrasonic medium 8 and the test material 3.
It is refracted at the point and propagates through the test material 3 at a refraction angle β.

At this time, the center A of one operating ultrasonic transducer group of the array type probe 1, the ultrasonic beam incident point B on the specimen 3, and the reference point of the array type probe 1 (in this case, the ultrasonic transducer group Sound wave vibrator 9 (
The relationship between i) and 0 is expressed by the following formula (1), where C is the point where the normal to the surface of the specimen 3 passing through the incident point B intersects with the radiation surface of the array probe 1. , (2), (3).

0A=(i-"dimension"=0°+0A01.(1) OA-
Jls ・tan a -12
) α=sln-' (5inl/), +
＋、.

However, Ll: Distance between test material and probe Ct: Sound speed of IIA sound medium C2: Sound speed of test material d: Transducer array interval Here, the test material surface and the ultrasonic radiation surface of the probe are parallel Since the ultrasonic beam deflection angle θ in the ultrasonic medium 8 and the ultrasonic beam incident angle α on the test material 3 take the same value, the The relationship between the refraction angle β of the ultrasound beam 2, the ultrasound beam deflection angle θ, and the range J of the ultrasound transducer group operating at that time is expressed by the above equation (11, (
2) and (3) can be rearranged and expressed as the following equation (4).

...(Kagashi) However, []: Takes an integer value and is the number of the vibrator.

l: Number of transducers that operate simultaneously By giving the distance from the reference point, 0C, as a constant value, the deflection angle within the operating transducer group and the ultrasonic medium 8 necessary to obtain the ultrasonic beam passing through the incident point B at the refraction angle β. θ is determined by calculating according to equation (4).

As a result, the signal controller 15 generates transmission pulses for the transmission delay setter 11 and the reception delay setter 14 so as to perform the above-mentioned 'aIll' and select the transducer group 9 to be activated, prior to transmission and reception of ultrasonic waves. A transmission delay setting device controls the output of the signal and the output of the trigger signal for starting the digital conversion of the received signal, and also sets the timing of ultrasonic transmission and reception of each transducer group that operates so that a predetermined ultrasonic beam deflection angle θ is achieved. 11 and reception delay setter 14, the transmission pulse generation trigger controls the signal output timing, and the reception signal digital conversion start trigger controls the signal output timing. In this way, by sequentially changing the refraction angle β of the ultrasonic beam to the test material 3 and repeating the above operation, the incident point B of the ultrasonic beam 2 to the test material 3 can be set as shown in FIG. Fixed-point sector electronic scanning is performed.

In receiving the ultrasonic waves, if the timing of transmitting and receiving the ultrasonic waves at approximately the center point A of the operating ultrasonic transducer group shown in FIG. The digital waveform addition received signal includes an ultrasonic beam path valve in the ultrasonic medium 948 between the point Δ and the ultrasonic beam incident point 8, and the beam path length is determined by the ultrasonic beam deflection angle θ. As a result, signal processing for creating an image sweep signal in image display becomes complicated.

Therefore, the signal controller 15 instructs the received signal setter 14 to set the trigger for starting the digital conversion of the received signals from each of the operating transducer groups, which is necessary to set the above-mentioned ultrasonic beam deflection angle θ. A bias is added to the reception delay time so that the output timing is delayed by the time tab required for round-trip propagation over the AB distance.

The bias tab of this reception delay time is the distance between the array type probe surface and the surface of the test material 1! and the ultrasonic beam deflection angle θ are expressed by the following equation (5).

However, θ−α Therefore, the calculation of the above equation is performed in the signal controller 15 along with the calculation of the above equation 4) every time the ultrasonic beam incident point B and the deflection angle θ are set or changed, and the signal is sent to the reception delay setting device 14. By setting the reception delay time, the received signal waveform digitally added in the waveform addition memory 16 becomes only the ultrasonic received signal in the specimen 3 starting from the ultrasonic beam incident point B.

In other words, an operation equivalent to sector electronic scanning using the direct contact method centered on the incident point B of the ultrasonic beam 11 is performed.

Here, when the signal processor 17 generates an image sweep signal to the B scope display 18 corresponding to the input of the received signal waveform from the addition memory 16, it generates the image sweep signal in the same way as the image sweep signal in the direct contact method. According to the following formula (6)i7), B
The X-axis and Y-axis signals to the scope display 18 are converted to the ultrasonic beam refraction angle β to the specimen 3 and the time axis T of the received signal (ultrasonic beam incident point B (equivalent to the beam path from).

X-T-sinβ...(aY
-T-cosβ (7) Therefore, the signal processor 17 sends out the image sweep signals X and Y to the B scope display 18 in synchronization with the output of the waveform addition memory, and at the same time, with the signal strength of the addition waveform, B scope display 1
It is also possible to display a B-scope image corresponding to sector scanning of the ultrasonic beam into the specimen 3 by modulating the brightness of the image sweep signal to the specimen 8.

In the embodiment described above, the case where the ultrasonic emission surface of the array type probe 1 and the surface of the specimen 3 are kept parallel to each other at a distance of 11 and sector electronic scanning is performed via the ultrasonic medium 8 is explained. However, as shown in Fig. 4, the array type probe 1
When the angle between the ultrasonic radiation surface of , the geometrical positional relationship between the reference point O of the array type probe 1 and the ultrasonic beam incidence point B on the specimen 3 was clarified, and the above-mentioned equations (a) and (5) were slightly modified. It can be applied by simply doing so.

That is, when the angle between the ultrasonic emission surface of the array type probe 1 and the surface of the test material 3 shown in FIG. The relationship between the refraction angle β, the ultrasonic beam deflection angle θ in the ultrasonic beam quality 8, and the range J of the ultrasonic transducer group that operates at that time is determined by modifying equation 4 as shown in equation (8) below. It can be obtained with

...(8) However, [ ] takes an integer value and is the transducer NO. m is the number of transducers that operate simultaneously. Also, the bias tab of the reception delay time when receiving ultrasonic waves is calculated by converting the above formula (5) to the following: It can be transformed as shown in formula (■).

・・・■ However, θ−α−ψ Also, regarding the surface shape of the flaw detection surface having the curvature shown in Fig. 5, the straight line connecting the center of curvature P and the point of incidence of the ultrasonic beam on the specimen material B should be connected to the point of incidence B. If considered as a normal line, the relationship W1 between the tangent 1i17' perpendicular to it and the array type probe 1 is the same as shown in Fig. 4, and therefore, equation (8)
And formula (2) can be applied as is and is included in the present invention.

In the above explanation, the received ultrasonic signal waveform is subjected to high-speed analog-to-digital conversion and waveform addition is performed in digital quantities.
(Charge Coupled Device)
It goes without saying that the same effect can be achieved by performing waveform addition using an analog circuit using a delay line or the like.

Furthermore, according to the present invention, the array type probe (1) reference point 0
It can also be used for sector scanning in the direct contact method, which is a flaw detection method in which the distance JL1 between the surface and the surface of the test material 3 is set to 0. It can also be used by switching, and it can also be used in conjunction with the electron focusing method. The same effect can be obtained even if

[Effects of the Invention] As described above in detail based on the embodiments, according to the present invention, sector electronic scanning is performed via an ultrasonic medium between an array type probe and the surface of a test material. Even in cases where the ultrasonic beam passes through the boundary between the ultrasonic medium and the test material, an array-type probe is used so that the point of incidence of the ultrasonic beam on the test material remains approximately constant regardless of the refraction angle. The selection of the group of transducers operated by the transducer and the deflection angle of the ultrasonic beam in the ultrasonic medium are corrected according to the angle of refraction toward the specimen, eliminating the need for special image processing. (The point of incidence of the ultrasonic beam on the specimen is a constant point regardless of the deflection angle of the ultrasonic beam, so the geometry of the reference point of the array probe and the ultrasonic reflection source is Academic rank W11
It is possible to provide an ultrasonic flaw detection method that can be easily known by the Il staff and can quickly and accurately evaluate the properties of defects that have an ultrasonic anti-tI of 4m.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of an apparatus for carrying out ultrasonic flaw detection according to the present invention, and Figs. 2 to 5 are for explaining the operation of the embodiment, and Fig. 2 is an array type An explanatory diagram when performing sector electronic scanning through a medium so that the ultrasonic emission surface of the probe and the surface of the specimen are parallel. Figure 3 shows the point of incidence of the ultrasonic beam on the specimen. Figures 4 and 5 are explanatory diagrams for performing sector electronic scanning with fixed point .
Figures 6 to 8 are for explaining the sector electronic scanning in the case of the conventional ultrasonic flaw detection method.
The figure shows a general direct contact method in which an array type probe is brought into direct contact with the surface of the material being tested. Figure 8 is a diagram to explain the state of the ultrasonic beam passing through the boundary of FIG. 2... Ultrasonic beam, 3... Test material, 8... Ultrasonic medium, 9... Ultrasonic vibrator, 11... Signal controller, 18... B scope indicator, O...Array type probe reference point, B...Ultrasonic beam incidence point, Jll...
Distance between array type probe and test material, α...Incidence angle, β...
...Refraction angle, θ... Ultrasonic medium deflection angle, φ... Probe tilt angle. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 3 Figure 7 Figure 8 Figure 6 (a) (C) (b) (d)

Claims (2)

[Claims] (1) Electronically controls the timing of ultrasonic wave transmission and reception by each vibrator of an array type probe placed on the surface of the specimen via an ultrasonic medium, and scans the inside of the specimen in a fan shape. In an ultrasonic flaw detection method in which a B-scope image is displayed to detect defects inside the test material, the point of incidence of the ultrasonic beam on the test material is approximately constant regardless of the ultrasonic beam deflection direction. In this way, the selection of the transducer group that the array type probe operates on and the selection of the deflection angle in the ultrasonic medium are performed for each ultrasonic beam refraction angle toward the desired specimen material. An ultrasonic flaw detection method characterized in that the flaw detection is determined based on the geometrical positional relationship with the point of incidence of the ultrasonic waves on the material to be inspected. (2) The timing of receiving the ultrasonic waves should be selected so that the ultrasonic waves are only transmitted for the time necessary for reciprocal propagation between the approximate center of the operating ultrasonic transducer group and the distance between the ultrasonic beam incident point on the specimen material. Select the reception timing of each ultrasonic transducer by biasing the reception delay time required for intra-medium ultrasonic beam deflection, and select the point of incidence on the specimen as the base point of image sweep in the B scope display. An ultrasonic flaw detection method according to claim (1), characterized in that: