JP2609647B2 - Ultrasonic flaw detector - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial application field) The present invention relates to an ultrasonic flaw detection apparatus used for destructive inspection of a flaw detection target such as a turbine disk.

(Prior art) This type of ultrasonic flaw detector that has been already proposed is
It is configured as shown in FIG. 13 and FIG.

That is, in FIGS. 12 and 13, the turbine rotor serving as the flaw detection object W is mounted on a turbine shaft a. In other words, the turbine disk W ₁ is hub W ₂ and the web W ₃
And a keyway W ₄ formed in the hub W _2.
The key W ₅ is integrally fixed and the turbine shaft a.

Therefore, when inspection by the ultrasonic flaw detection by non-destructive inspection of the defect (a crack portion) W ₆ that occurs the keyway W ₄ as the target Sagukizutai W, ultrasonic outer peripheral surface of the hub portion W ₂ This is performed by placing the contactor b in contact.

That is, the by emitted from the ultrasound probe b ultrasonic beams B into the keyway W _4, the distal end portion and the reflected wave due to the shape of the keyway W ₄ of the defect W ₆ (reflection echo) above The signal is received by the receiving unit of the ultrasonic probe b.

Then, as shown in the graph of FIG. 13, the ultrasonic probe b is a defective portion W ₆ detects the echo level b _1, while the shape of the keyway W ₄ is shifted by beam path length difference Δl detecting the echo level b ₂ to the position. Also, the above echo level b ₁
The defect depth d is usually measured as d = Δl, based on the beam path difference Δl between the echo level ₂ and the echo level ₂ .

On the other hand, when an inspection by the ultrasonic flaw detection of the keyway W ₄ when the generated defect W ₆ located below the web W ₃ of the object to be Sagukizutai W, as shown in FIG. 14 and FIG. 15 Done.

That is, provided side by side above the web W ₃ for sending to the outer periphery of the hub portion W ₂ located on both sides (for transmission) angle probe c and the receiving probe d.

Next, than to transmit the ultrasound beam B at an angle β from the call origination angle probe c, the ultrasonic beam B is substantially about 45 ° incident angle γ on the front end of the defective portion W ₆ The probe refraction angle β is set as follows. Then, the reflection echo at the distal end of the defective portion W ₆ being received by the probe d probe for the reception. Furthermore, it inspected while moving the outer periphery of the hub portion W ₂ circumferentially to sync probe d probe for receiving the probe c probe for the originating.

In this way, by moving in the circumferential direction in synchronism with probe d probe for receiving the probe c probe for the originating, flaw detection throughout the keyway W _4.

The ultrasonic waveform data obtained by the ultrasonic beam B of the transmitting probe c and the receiving probe d is obtained by using a signal processing method having an algorithm called an ALOK method.
It is adapted to measure the defect W ₆ and its dimensions.

In particular, as shown in FIG. 14, by the key W ₅ which is fitted into the key groove W ₄ is pressed against the keyway W ₄ in the circumferential direction of the stress, the presence in the key W ₅ and keyway W ₄ Due to the influence of the scale, pseudo echoes may be detected from the key corners (key corners) c ₁ and c _2, and the “orientation” after signal processing of the ultrasonic waveform information detected in the state of the pseudo echoes result"
As shown in FIG. 15, the measurement result (also referred to as a measurement result) is located at a position corresponding to each of the key corners c ₁ and c ₂ as an indication. Further, even when there is no the defect W _6,
Each indication by pseudo echo as mentioned above
Since c ₁ and c ₂ are located, there is a possibility that even when no defect exists, it is erroneously detected as if there is a defective portion.

(Problems to be Solved by the Invention) As described above, the ultrasonic flaw detection means described above uses the flaw detection target W
When defect inspection keyway W ₄ in the turbine disc as there is a possibility of detecting the echo replica affected by keyway W ₄ and key W ₅ or scale, etc., it is determined that the defect portion by mistake the echo replica There are problems such as misidentification.

The present invention has been made in view of the above circumstances, and in an ultrasonic inspection apparatus for nondestructively inspecting an object to be inspected, each probe of a transmitting multi-ultrasonic probe and a receiving multi-ultrasonic probe are used. Each probe of the acoustic probe is transmitted and received at different refraction angles to distinguish a defective echo detected from a defective portion from a pseudo echo, or to remove a pseudo echo and to heighten a defective portion. It is an object of the present invention to provide an ultrasonic flaw detector which detects the size of a defective portion while detecting it with high accuracy.

[Configuration of the invention]

(Means for Solving the Problems and Their Functions) In order to achieve the above object, the present invention includes a pair of scanners that are arranged so as to be able to run in synchronization with the outer periphery of a flaw-detected body, The first transmitting probe and the second
A transmitting multi-ultrasonic probe including a transmitting probe of a first type is provided, and a first receiving probe and a second
A receiving multi-ultrasonic probe including a receiving probe is provided, wherein the first transmitting probe and the first receiving probe have a probe refraction angle of about 40 to 50 degrees with respect to each other. And the second transmitting probe and the second receiving probe have a probe refraction angle of about 65 to 75 degrees with respect to each other, and detect the pseudo echo. A central echo processing unit, an A / D converter, and a signal processor, which detect a defect echo without detecting the signal and obtain a signal obtained by transmission / reception of the transmission multi-ultrasonic probe and the reception multi-ultrasonic probe. And the signal processor is detected by the first transmitting probe and the first receiving probe and not detected by the second transmitting probe and the second receiving probe. The echo is characterized as a pseudo echo.

In the present invention having such a configuration, the pair of scanners are driven in synchronization with the outer periphery of the flaw-detected body, and the first transmitting probe of the transmitting multi-ultrasonic probe provided in one of the scanners is provided. An ultrasonic wave is transmitted from the probe, and the ultrasonic wave is received by the first receiving probe of the receiving multi-ultrasonic probe provided in the other scanner. Here, since the first transmitting probe and the first receiving probe have a probe refraction angle of about 40 to 50 degrees with respect to each other, a defect echo and a pseudo echo are generated by these probes. Are detected.

On the other hand, the transmission source of the ultrasonic wave is switched to the second transmission probe of the transmission multi-ultrasonic probe to transmit the ultrasonic wave, and this ultrasonic wave is used for the second reception of the multi-ultrasonic probe for reception. Receive with the probe. Here, since the second transmitting probe and the second receiving probe have a probe refraction angle of about 65 to 75 degrees with respect to each other, a pseudo echo is detected by these probes. A defect echo is detected without any problem.

The signals obtained by the transmission and reception of the transmitting and receiving multi-ultrasonic probes are sent to a central processing unit,
It is displayed on the display through the D converter and the signal processing device. Here, the signal processing device locates an echo detected by the first transmitting probe and the first receiving probe and not detected by the second transmitting probe and the second receiving probe as a pseudo echo. I do.

(Embodiment) An embodiment shown in the drawings, in which the present invention is applied to a defect inspection of a fitting surface between a turbine disk and a rotor shaft and a key groove, will be described below.

Note that, in the present invention, the same components as those in the specific example described above are denoted by the same reference numerals and described.

In Figure 1, reference numeral 1 is a pair of scanners mounted for travel so as to sandwich the web W ₃ on the outer circumference of the hub W ₂ of test object body W, the scanner 1 of this one is , A transmitting multi-ultrasonic probe 3 is provided. In addition, in this transmitting multi-ultrasonic probe 3, about 40
The first transmitting probe 3a for transmitting ultrasonic waves at an inclination angle of the probe refraction angle βi (γi) of about 50 to 50 degrees and the inclination angle of the probe refraction angle βi (γi) of about 65 to 75 degrees The second scanner 2 is provided with a second transmitting probe 3b, 3c for transmitting ultrasonic waves, and the other scanner 2 is provided with a receiving multi-ultrasonic probe 4. Furthermore, the probe multi-ultrasonic probe 4 has a probe refraction angle βi (γ) of about 40 to 50 degrees.
i) about the first receiving probe 4a for receiving ultrasonic waves at the inclination angle
Second receiving probes 4b and 4c for receiving ultrasonic waves at an inclination angle of the probe refraction angle βi (γi) of about 65 to 75 degrees are provided.

On the other hand, a scanner controller 5 is connected to both scanners 1 and 2 via respective lead wires 6a and 6b.
A central processing unit (CPU) 7 and a position detector 8 are connected to the scanner controller 5. or,
The transmitting multi-ultrasonic probe 3 and the receiving multi-ultrasonic probe 4 are provided with a multi-channel pulsar receiver group 9.
Are connected via lead wires 10a and 10b, and the central processing unit (CPU) 7 and the A / D converter 11 are connected to the multi-channel pulsar receiver group 9.
Further, the central processing unit 7 and the A / D converter 11 include:
A signal processor that incorporates, as software, an algorithm called the ALOK method using the ultrasonic waveform data converted into digital values and the probe position information detected by the position detector 8.
The signal processor 12 is connected to a display 13 for displaying the result of the signal processing.

In particular, the first transmitting probe 3a and the first receiving probe 4a
Incident angle of the ultrasonic beam B, that is, the probe refraction angle βi
It has been confirmed that (γi) has the maximum sensitivity experimentally at 45 degrees, for example, and shows the echo level shown in the graph of FIG. 3, and the incident angle γi of the ultrasonic beam B
Is 45 degrees, a pseudo echo is clearly detected, but it is experimentally confirmed that no pseudo echo is detected under the damage condition in which the incident angle γi is 70 degrees.

Also, as is apparent from the graph of FIG. 3, the defect portion W ₆
The change in the level of the reflected echo from
At 60 ° it is constant at high echo levels, but the incident angle γ
It has been confirmed that when the incident angle suddenly decreases at i ≒ 60 degrees and exceeds the incident angle γi = 60 degrees, the reflected echo gradually increases, and the reflected echo is detected at a sufficient echo level near γi ≒ 70 °.

In this way, at the incident angle γi {70}, as shown in the graph of FIG. 5, defect flaw detection can be performed and a defect echo can be detected, but a pseudo echo is not detected.
A probe having a probe refraction angle βi of 70 ° can be used as a probe for discriminating between a pseudo echo and a defect echo.

Next, the originating multi ultrasonic feeler unit 3 and the reception multi ultrasonic feeler device 4, as shown in FIGS. 6 and 7, the hub W ₂ by the scanner 1 and 2 and When the outer peripheral surface is moved synchronously, as shown in FIG. ₆ , when there is a defect W6 in the inspected body W, as shown in FIG.
When no defect portion W ₆ in test object member W, the originating multi ultrasonic each call origination probe 3b of the feeler device 3, 3c and feeler for each reception of the reception multi ultrasonic feeler device 4 child 4b, the flaw detection by receiving this 4c to disseminate the ultrasonic beam B, e.g., when testing the entire keyway W _4, each call origination probe 3b, 3c
8 (a), 8 (b) and 8 (c), the relationship between the positions of the receiving probes 4b and 4c and the path of the ultrasonic beam B was obtained.

That is, Figure 8 (a), (b), (c), the results testing when there is a defect portion W ₆ being the keyway W _4, according to the probe 4c probe for receiving the originating for probe 3c In the case of damage, a false echo is detected in addition to the defect corner echo, the defect edge echo, and the shape echo. Also, in the case of flaw detection by the transmitting probe 3b and the receiving probe 4b for pseudo echo identification, a defect corner echo and a shape echo are detected, but a pseudo echo and a defect end echo are not detected. The final orientation result obtained by performing signal processing on these two pieces of flaw detection data using an algorithm called the ALOK method is used to determine the defect size d as shown in FIG. 8 (c).

On the other hand, as shown in FIG. 7, the defect portion W keyway W _{4 6}
The damage result in the case where there is no defect is detected by the transmitting probe 3c and the receiving probe 4c for measuring the defect size, and the pseudo echo is transmitted by the transmitting probe 3b and the receiving probe for identifying the pseudo echo. Child
Since no detection is performed by flaw detection using 4b, and only a shape echo is detected at this time, signal processing is performed by the signal processor 12 as described above, as shown in FIG. 8 (c). In addition, a “location result” can be obtained.

Thus, when a defect inspection in contact with or pressed against a state in keyway W ₄ in various conditions, the angle of incidence .gamma.i ≒ 70
損傷 If the second transmitting probe 3c and the second receiving probe 4b having the flaw detection conditions near each other are damaged, a defective echo is detected but a pseudo echo is not detected. Also, the incident angle γi {45} of the first transmitting probe 3a and the first receiving probe 4a for detecting the defect edge echo with high sensitivity, the second transmitting probe 3b and the second receiving probe By using the probe in combination with the probe 4b, it is possible to measure the defect size with high accuracy, so that an appropriate defect can be inspected.

Therefore, now, as shown in FIG. 1, a pair of scanner 1 and 2 was placed along the outer periphery of the hub W ₂ by transferring synchronously probe outgoing multi ultrasound one scanner 1 above by transmitting the ultrasonic beam B of the refractive angle of 45 ° from the first call origination probe 3a tactile device 3, the ultrasonic beams B detects the defect W _6, a defect echo other scanner 2 The signal is received by the first receiving probe 4a, and the multi-channel pulsar receiver group 9-A / D converter 11-signal processor 1
The information is displayed on the display 13 via 2.

On the other hand, switching to the second transmission probe 3b, 3c of the transmission multi-ultrasonic probe 3, the second transmission probe 3b, 3c
, An ultrasonic beam B having a refraction angle of 70 ° is transmitted from the detector, the ultrasonic beam B detects a defect portion W ₆ , and the defect echo is received by the second receiving probes 4 b and 4 c of the other scanner 2. And multi-channel pulsar receiver group 9-A / D
The information is displayed on the display 13 via the converter 11 and the signal processor 12.
At this time, these displays are displayed as shown in FIGS. 8A, 8B, and 8C as described above.

Next, FIGS. 9 and 11 show another embodiment of the present invention, in which an array type probe is used instead of the transmitting multi ultrasonic probe 3 and the receiving multi ultrasonic probe 4. It is a child.

That is, in contact with the shoes 14 and 15 on the hub portion W _2,
In addition, these shoes 14, 1
Transmitting array probe with multiple transmitting transducers 16a in 5
16 and a receiving array probe 17 having a large number of receiving transducers 17a, each of the transducers 16a, 16b, 17
By setting the refraction angles of a and 17b to be 45 ° and 70 °, a highly accurate defect inspection can be performed.

In addition, each transducer 16a, 16b and 17a, 1
7b is but illustrates the circumferential direction of the hub portion W _2, within a range not changing the gist of the present invention, for example, is of course that it may be arranged in the axial direction.

On the other hand, the present invention can apply the damaged body W to two structures W ₇ and W ₈ as shown in FIG.
Even in such a flaw detection object W, the eleventh (a),
As shown in the graphs of (b) and (c), the defect can be detected.

〔The invention's effect〕

As described above, according to the present invention, about 40 to 50
A first transmitting probe and a first receiving probe having a probe refraction angle of about degree and detecting a defect echo and a pseudo echo, and a probe refraction angle of about 65 to 75 degrees with respect to each other. A second transmitting probe and a second receiving probe for detecting a defective echo without detecting a pseudo echo having a first transmitting probe and a first receiving probe The echo detected by the second transmitting probe and not detected by the second receiving probe is determined as a pseudo echo by the signal processing device, so that the detected echo is replaced with a defective echo and a pseudo echo. It is possible to identify the defect echo by distinguishing between them, so that not only can the defect size and the like be measured with high accuracy, but also that the false echo is erroneously recognized as the defect echo and the wrong judgment is not made, Extremely reliable measurement results can be obtained .

[Brief description of the drawings]

FIG. 1 is a diagram showing an ultrasonic flaw detector of the present invention, FIGS. 2 to 8 are diagrams for explaining the operation of the present invention, and FIGS.
FIGS. To 11 (a), (b) and (c) show other embodiments of the present invention, and FIGS. 12 to 15 show an already proposed ultrasonic flaw detector. It is each diagram. 1,2 ... Scanner, 3 ... Transmission multi-ultrasonic probe, 3a ... First transmission probe, 3b, 3c ... Second transmission probe, 4 ... Reception multi-ultrasonic probe Acoustic probe, 4a ... first receiving probe, 4b, 4c ... second receiving probe.

Claims (1)

(57) [Claims] A pair of scanners which are arranged so as to be able to run in synchronization with the outer periphery of a flaw-detected body comprising a structure having a structure for generating a pseudo echo ahead of a region to be inspected in a transmission direction of an ultrasonic wave; A transmitting multi-ultrasonic probe including a first transmitting probe and a second transmitting probe is provided on one of the scanners, and a first receiving probe and a second receiving probe are provided on the other of the scanners. A receiving multi-ultrasonic probe including a receiving probe, wherein the first transmitting probe and the first receiving probe have a probe refraction angle of 40 to 50 degrees with respect to each other; To detect a defective echo and a pseudo echo, and the second transmitting probe and the second receiving probe have a probe refraction angle of 65 to 75 degrees with each other and without detecting the pseudo echo. Detecting a defect echo and transmitting / receiving the multi-ultrasonic probe for transmission and the multi-ultrasonic probe for reception Thus obtained signal the central processing unit, A / D converter and displayed on the display unit through the signal processor, the signal processor is probe for the first outgoing probe and the first
The second transmitting probe detected by the receiving probe and the second transmitting probe
An ultrasonic flaw detector wherein echoes not detected by the receiving probe are located as pseudo echoes.