JP2002071332A - Probe for measurement thickness of clad steel ply material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe for the measurement of the thickness of a clad steel ply material, with which the thickness of a multilayer piled ply material can be measured with satisfactory accuracy, by reducing the influence due to reflected echoes from a part between layers of the ply material. SOLUTION: A vibrator 2 for transmission and a vibrator 3 for reception are arranged on a wedge face 4, at an angle (i) at which the reflected echo is efficiently converted into transverse waves with on a flaw detection face 11. The interprobe distance L between the vibrator 2 and the vibrator 3 is set at a distance, which is smaller than interval L2 found geometrically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe for measuring the thickness of a clad steel laminate, which measures the thickness of the clad steel laminate.

[0002]

2. Description of the Related Art Clad steel is made of G0601 according to JIS.
As described in (1989), a base material such as a steel material is coated over the entire surface with a bonding material such as stainless steel or a nickel alloy, and a boundary surface thereof is metallographically bonded. Are better.

As a conventional measuring method for measuring the thickness of a clad steel clad material, as described in Japanese Patent Application Laid-Open No. 8-219750, a single vibrator for transmitting and receiving is provided. A single-type vertical-wave vertical flaw detector that transmits and receives longitudinal ultrasonic waves perpendicular to the flaw detection surface, and a transmission transducer and a reception vibrator are provided independently and provided on the flaw detection surface. Longitudinal wave vertical flaw detection methods, such as those using a two-piece longitudinal wave vertical flaw detector that transmits and receives longitudinal ultrasonic waves vertically, are known.

[0004] This is an ultrasonic flaw detection test of austenitic stainless steel used as a cladding material for clad steel, which is described in an ultrasonic flaw detection test of various products and welded structures issued by the Japan Non-Destructive Inspection Association (1989). In order to reduce the effects of forest-like echo noise and ultrasonic sound velocity anisotropy due to reflection from the columnar crystal structure, flaw detection using a longitudinal wave detector or a broadband type flaw detector is considered to be suitable. Yes,
This is because the vertical flaw detection method using a longitudinal wave flaw detector or the like has been performed based on the idea that the same applies to the measurement of the thickness of the clad steel clad material.

FIG. 6 is a block diagram showing a conventional clad steel laminated material thickness measuring apparatus using a two-piece longitudinal wave vertical probe by a longitudinal wave vertical flaw detection method.

The flaw detection surface 1 of the laminated material 9 coated on the base material 10
1, a probe 1 having a transmitting transducer 2 and a receiving transducer 3 disposed on a wedge 4 is disposed, and a flaw detector for controlling transmission and reception of ultrasonic waves to the respective transducers 2 and 3 2
2 are connected. The probe 1 includes a couplant supply device 28
The scanner 2 controlled by the scanner controller 24 while supplying ultrasonic couplant to the flaw detection surface 11 from the
3, scanning is performed, and ultrasonic data from the flaw detector 22 and position signal data from the scanner 23 are recorded by the data recording processing device 25 to obtain thickness measurement data. The result of the data recording processor 25 is displayed on the monitor 2
6 and printed out by the printer 27. Here, the surface angle of the wedge 4 on which the vibrators 2 and 3 are arranged is set to a small angle at which the longitudinal wave is hardly mode-converted into the transverse wave on the flaw detection surface 11.

Now, the transmitting transducer 2 in the probe 1
When a longitudinal wave is incident on the clad steel clad material 9 to be measured by the excitation signal 29 from the flaw detector 22 via the wedge 4, the longitudinal wave is generated at the boundary surface 1 between the base material 10 and the clad material 9.
The reflected light is received by the receiving vibrator 3 via the wedge 4, and a received signal 30 is output to the flaw detector 22. At this time, the wedge 4 on which the vibrators 2 and 3 are arranged as described above
Is set to a small angle at which the longitudinal wave is less likely to be mode-converted into the transverse wave on the flaw detection surface 11, so that the longitudinal wave can be efficiently incident on the bonding material 9. In the flaw detector 22, processes such as amplification and detection are performed based on the received signal 30, and output to the data recording processing device 25 as an output 33. At this time, the probe 1 can scan the flaw detection surface 11 in the required measurement range in the front, rear, left, and right directions by the scanner 23 controlled by the control signal 31 from the scanner controller 24. Further, a position signal 32 from a position detector such as an encoder built in the scanner 23 is input to the data recording processing device 25 together with an output signal 33 from the flaw detector 22 to perform a recording process, and the thickness of the material 9 in the measurement range is measured. The distribution is output as a measurement result to the monitor 26, the printer 27, or the like.

[0008]

However, the above-mentioned conventional clad steel laminated material thickness measuring device can easily measure the thickness of the laminated material 9 if the laminated material 9 has a simple single-layer structure. However, when the composite material 9 has a multilayer structure, the influence of the reflected echo from between the layers of the multilayer composite material becomes an obstacle, and the thickness cannot be measured accurately.

That is, as shown in FIG. 11, the A-scope display waveform of the clad steel laminated material thickness measuring apparatus using the conventional two-piece vertical wave vertical probe is shown by the reflection echo 17 from the boundary surface 12 as shown in FIG. A reflected echo 18 from between layers appears before.
In order to measure the thickness of the bonding material 9 by the automatic flaw detection, the flaw detection gate 19 is set as shown in the figure to evaluate the reflected ultrasonic signal, and the flaw detection gate 19 has the maximum reflection intensity existing in the flaw detection gate 19. The thickness of the bonding material 9 is determined from the propagation time of the reflected echo. Therefore, as shown in FIG. 7A, if the reflection intensity of the reflection echo 17 from the boundary surface 12 between the base material 10 and the composite material 9 is larger than the reflection echo 18 from the interlayer, a correct thickness measurement value is obtained. As shown in FIG. 7B, if the reflection intensity of the reflection echo 18 from between the layers is higher, an erroneous thickness measurement value is indicated. In particular, since the structure of the multi-layered composite material 9 is not uniform, the propagation characteristics of ultrasonic waves are also non-uniform, and the reflection intensity of the reflected echo 17 from the boundary surface between the base material 10 and the composite material 9 varies greatly depending on the portion. The reflected echo 18 from between the layers is
In many cases, the reflection echo 17 from the boundary surface of the bonding material 9 is larger than the reflection echo 17, and an erroneous thickness measurement result is shown in that portion.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the influence of reflection echoes between layers of a multi-layered laminated material and to accurately measure the thickness of the laminated material. Is to provide.

[0011]

According to the present invention, in order to achieve the above object, a wedge is arranged on a flaw detection surface of a laminated material coated on a base material, and a transmitting oscillator and a receiving oscillator are placed on the wedge. In the clad steel composite material thickness measuring probe for measuring the thickness of the composite material by receiving the ultrasonic waves from the transmitting transducer by the receiving transducer, the transmitting transducer And the receiving transducer are arranged at an angle for efficiently converting to a shear wave on the flaw detection surface, and the inter-probe distance between the transmitting transducer and the receiving transducer is geometrically changed. The distance is smaller than the calculated interval.

A probe for measuring the thickness of a clad steel laminated material according to the present invention has a transmitting oscillator and a receiving oscillator arranged at an angle for efficiently converting to a shear wave on a flaw detection surface, and a transmitting oscillator. The distance between the transducers between the transducer and the receiving transducer is made smaller than the geometrically determined distance, so that the effect of the reflected echo from the layers of the multi-layered assortment is reduced and the S / N ratio is improved. Since flaw detection can be performed, the thickness of the clad steel laminated material can be automatically measured with high accuracy.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a probe for measuring the thickness of a clad steel laminated material according to the present invention.

A base material 10 is provided with a bonding material 9 to be measured, and the probe 1 is arranged on a flaw detection surface 11 of the bonding material 9. In this probe 1, a transmitting vibrator 2 and a receiving vibrator 3 are disposed via a wedge 4 disposed on a flaw detection surface 11 of a bonding material 9, and a direct signal is applied between the two vibrators 2, 3. A sound insulating plate 5 for preventing propagation is provided.
The transmitting vibrator 2 and the receiving vibrator 3 are fixed on the wedge 4 at an angle i at which the flaw detection surface 11 efficiently converts them into transverse waves, as will be described in detail later. A transmitting connector 7 connected to the transmitting vibrator 2 via a damper member 6 for suppressing vibration so as to input an excitation signal from a flaw detector described later.
And a receiving vibrator 3 for outputting a received signal to the flaw detector.
Is connected to the receiving connector 8.

The flaw detector side, which is not shown in detail, has the same configuration as that of FIG. 6 described above, for example, and the transmitting transducer is brought into contact with the flaw detection surface 11 of the mating member 9 while the probe 1 is in contact therewith. The ultrasonic wave is transmitted from the base material 10 and the reflected echo from the boundary surface 12 of the combined village 9 with the base material 10 is received by the receiving vibrator 3. The thickness of the combined material 9 is reduced by arithmetic processing on the flaw detector. It is configured to calculate. The thickness of the composite material 9 is
From the received signal, it can be obtained by measuring the propagation time from when the ultrasonic wave enters the flaw detection surface 11 until it is reflected by the boundary surface 12 and returns to the flaw detection surface 11.

FIG. 2 shows a display waveform of the flaw detector, that is, an A-scope waveform, which has been subjected to signal processing based on a signal received from the probe 1.

For the transmission echo 15, a surface echo 16 from the flaw detection surface 11 of the composite material 9, a reflected echo 17 from the boundary surface 12, and a reflected echo 18 between layers of the composite material 9 are shown. The measurement of the propagation time is based on the flaw detector A
The inspection is performed by setting a flaw detection gate 19 on the scope and measuring the propagation time of the reflected echo 17 from the boundary surface 12 existing in the flaw detection gate 19 using a counter or the like. The thickness P of the composite material 9 can be obtained by the following equation (1) based on the propagation time 20 of the reflected echo 17 from the boundary surface 12.

D = (Tb−Tw) × Cs / 2 (1) where Tb is the propagation time 20 of the reflected echo 17 from the boundary surface 12, Tw is the propagation time 21 in the wedge 4, and Cs is This represents the shear wave velocity of the composite material 9.

Next, the transmitting oscillator 2 and the receiving oscillator 3
Will be described with reference to FIG. 3 which is an enlarged view of a main part.

The transmitting vibrator 2 and the receiving vibrator 3 are fixed on the wedge 4 at an angle i at which the transmitted / received wave is efficiently converted into a transverse wave on the flaw detection surface 11. Since the transverse wave is bent in the vertical direction, the transmitting oscillator 2 and the receiving oscillator 3 are arranged at positions separated by an inter-oscillator distance L shorter than the interval L2 geometrically obtained by the equation (2). ing.

L <L2 = 2 × (L1 × tani + d × tanθ) (2) where L1 is the distance between the vibrators 2 and 3 and the flaw detection surface 11, and d
Represents the thickness of the composite material 9 and θ represents the refraction angle in the composite material 9.

The ultrasonic wave transmitted from the transmitting transducer 2 is
It is a longitudinal wave that oscillates in the same direction as the propagation direction.
After propagating through the inside, when entering the composite material 9, the angle i
Thereby, it is converted into a transverse wave oscillating on the flaw detection surface 11 in a direction perpendicular to the propagation direction. The mode conversion of ultrasonic waves at the boundary between different materials, that is, the phenomenon of conversion from longitudinal waves to shear waves, is described in, for example, Ultrasonic Testing 2 (1989) issued by the Japan Non-Destructive Testing Association. Is acrylic and the test object is steel, the angle i is set in the range of about 27 to 57 degrees, so that it can be efficiently converted into a transverse wave. At this time, the refraction angle θ incident on the bonding material 9 can be expressed by the following equation (3).

Θ = sin ⁻¹ (Cs / Cw × sini) (3) where Cs is the transverse sound velocity of the composite material, and Cw is the longitudinal sound velocity of the wedge 4.

The incident wave 13 incident on the bonding material 9 at a refraction angle θ is bent along the growth direction of the columnar crystal structure, and eventually propagates in a direction perpendicular to the flaw detection surface 11. Therefore, the incident ultrasonic wave appears apparently in the bonding material 9.
It has the same characteristics as vertical inspection. This phenomenon is
Document 1 mentioned above as a waveguide effect of transverse waves due to columnar crystals
It is also described in The incident wave 13 reaches the boundary surface 12 with the base material 10 and is reflected to become a reflected wave 14. The reflected wave 14 propagates through the matching member 9 along a path symmetrical to that at the time of incidence, and is received by the receiving wave oscillator 3.

According to Document 1, attenuation of longitudinal ultrasonic waves is the least when incident in the direction of 45 degrees with respect to the growth direction of the columnar crystal, and is good when the directions are 0 and 90 degrees.
On the other hand, it is said that the transverse wave is less attenuated when propagating in parallel to the growth direction of the columnar crystal. From this,
If the thickness of the clad steel laminated material 9 is measured using the shear wave oblique probe, it is expected that the fluctuation of the intensity of the reflected wave is small and the measurement is performed with uniform flaw detection sensitivity.

FIG. 4 shows the relationship between the inter-probe distance L and the detected peak value when a pair of transducers are arranged opposite to each other using a clad steel laminated material test piece and ultrasonic waves are transmitted and received at a shear wave oblique angle. FIG. 9 is a characteristic diagram obtained experimentally.

As can be seen from the figure, the distance L between the probes is
The shorter the distance, the better the detectability. The result is
This is consistent with the principle of ultrasonic transmission and reception due to the waveguide effect of the transverse wave by the columnar crystal. Therefore, the inter-probe distance L between the transmitting transducer 2 and the receiving transducer 3 in FIG. 3 described above is preferably set to be smaller than the geometrically obtained distance L2. In practice, a part of the ultrasonic beam transmitted and received by the transmitting transducer 2 and the receiving transducer 3 is not restricted by the sound insulating plate 5 arranged between the transmitting transducer 2 and the receiving transducer 3 so that the approach limit is not reached. In this case, the distance L between the probes is 10 mm to 25 mm.

FIG. 5 shows the case where a conventional dual element vertical wave vertical probe is used as a probe for measuring the thickness of clad steel clad material, and the dual element type shear wave oblique angle probe shown in FIG. FIG. 9 is a characteristic diagram obtained by comparing and measuring the intensity ratio between a boundary echo and a reflected echo from between layers when a stylus is used.

FIG. 3 shows a comparison of the echo intensity at a portion where the boundary echo is normally detected, and is different from the conventional two-element vertical-wave vertical probe in the two-element transducer shown in FIG. It can be seen that the shear wave oblique angle probe has a larger margin for lowering the level of the boundary surface echo. Accordingly, by using the two-transducer type shear wave oblique probe, as shown in FIG. 6B, the reflected echo 18 between the layers has a higher reflection intensity than the reflected echo 17 from the boundary surface 12. It is possible to reduce the number of places, and to detect the reflection echo 17 from the boundary surface 12 between the base material 10 and the composite material 9 to accurately measure the thickness of the composite material.

[0031]

As described above, the probe for measuring the thickness of clad steel clad material according to the present invention has an angle i at which the transmitting oscillator and the receiving oscillator are efficiently converted into a transverse wave on the flaw detection surface. And the distance L between the transducers between the transmitting transducer and the receiving transducer is smaller than the geometrically determined distance L2. Since the flaw detection can be performed with a good S / N ratio by reducing the thickness, it is possible to automatically and accurately measure the thickness of the clad steel composite material.

[Brief description of the drawings]

FIG. 1 is a front view showing a probe for measuring the thickness of a clad steel composite material according to an embodiment of the present invention.

FIG. 2 is a waveform diagram obtained by using the probe for measuring a thickness of a clad steel composite material shown in FIG. 1;

FIG. 3 is an enlarged view of a main part showing the principle of the probe for measuring the thickness of a clad steel composite material shown in FIG. 1;

FIG. 4 is a characteristic diagram showing a relationship between a distance between a transmitting and receiving probe and a detected peak value by the probe for measuring a thickness of a clad steel composite material shown in FIG. 1;

FIG. 5 is a characteristic diagram showing a comparison between intensity ratios of boundary echoes and reflection echoes between layers.

FIG. 6 is a block diagram of a conventional clad steel laminated material thickness measuring apparatus using a clad steel laminated material thickness measuring probe.

FIG. 7 is a waveform chart obtained by using the probe for measuring a thickness of a clad steel composite material shown in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Probe 2 Transmitting transducer 3 Receiving transducer 4 Wedge 5 Sound insulation board 9 Laminated material 10 Base material 11 Flaw detection surface 12 Boundary surface L Distance between probes i Angle

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[Procedure amendment]

[Submission date] October 23, 2000 (2000.10.
23)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007] Now, a transmission transducer 2 or we in the probe 1, the incident longitudinal waves in clad steel alignment member 9 is measured by the excitation signal 29 from the wound 22 probe via a wedge 4, This longitudinal wave is generated at the interface 12 between the base material 10 and the composite material 9.
And is received by the receiving transducer 3 via the wedge 4, and outputs a reception signal 30 to the flaw detector 22. At this time, as described above, the surface angle of the wedge 4 on which the oscillators 2 and 3 are arranged is set to a small angle at which the longitudinal wave is hardly mode-converted into the transverse wave on the flaw detection surface 11, so that the longitudinal wave can be efficiently combined. It can be incident on the material 9. In the flaw detector 22, processes such as amplification and detection are performed based on the received signal 30, and output to the data recording processing device 25 as an output 33. At this time, the probe 1 can scan the flaw detection surface 11 in the required measurement range in the front, rear, left, and right directions by the scanner 23 controlled by the control signal 31 from the scanner controller 24. Further, a position signal 32 from a position detector such as an encoder built in the scanner 23 is input to the data recording processing device 25 together with an output signal 33 from the flaw detector 22 to perform a recording process, and the thickness of the material 9 in the measurement range is measured. The distribution is output as a measurement result to the monitor 26, the printer 27, or the like.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

That is, as shown in FIG. 7 , an A-scope display waveform of a clad steel laminated material thickness measuring apparatus using a conventional two-piece vertical wave vertical probe has a reflection echo 17 from a boundary surface 12 as shown in FIG. A reflected echo 18 from between layers appears before. In order to measure the thickness of the laminated material 9 by measurement by automatic flaw detection,
The flaw detection gate 19 is set as shown to evaluate the reflected ultrasonic signal, and the bonding material 9 is determined from the propagation time of the reflected echo having the maximum reflection intensity existing in the flaw detection gate 19.
Seeking thickness. Therefore, as shown in FIG. 7A, the reflected echo 1 from the boundary surface 12 between the base material 10 and the composite material 9
7 is a correct thickness measurement value if the reflection intensity is higher than the reflection echo 18 from the interlayer, but if the reflection intensity of the reflection echo 18 from the interlayer is higher as shown in FIG. Will show the measured values. In particular, since the structure of the multi-layered composite material 9 is not uniform, the propagation characteristics of ultrasonic waves are also non-uniform, and the reflection intensity of the reflected echo 17 from the boundary surface between the base material 10 and the composite material 9 varies greatly depending on the portion. However, the reflected echo 18 between the layers is often larger than the reflected echo 17 from the boundary surface between the base material 10 and the composite material 9, and this portion shows an erroneous thickness measurement result. Would.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

The incident wave 13 incident on the bonding material 9 at a refraction angle θ is bent along the growth direction of the columnar crystal structure, and eventually propagates in a direction perpendicular to the flaw detection surface 11. Therefore, the incident ultrasonic wave appears apparently in the bonding material 9.
It has the same characteristics as vertical inspection. This phenomenon is
Document 1 mentioned above as a waveguide effect of transverse waves due to columnar crystals
It is also described in The incident wave 13 is received by the interface 12 to reach reflected in next reflected waves 14, Doko 3 oscillation for receiving propagated combined material 9 by incident upon symmetrical path with the base material 10.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

FIG. 3 shows a comparison of the echo intensity at a portion where the boundary echo is normally detected, and is different from the conventional two-element vertical-wave vertical probe in the two-element transducer shown in FIG. It can be seen that the shear wave oblique angle probe has a larger margin for lowering the level of the boundary surface echo. Thus, by using a dual element type shear angle probe, towards the return echo 18 from the interlayer, as shown in FIG. 7 (b), larger reflection intensity than the reflective echo 17 from the interface 12 It is possible to reduce the number of places, and to detect the reflection echo 17 from the boundary surface 12 between the base material 10 and the composite material 9 to accurately measure the thickness of the composite material.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Kato 3-2-1 Sachicho, Hitachi-shi, Ibaraki Hitachi Engineering Co., Ltd. (72) Inventor Yasuhiro Mabuchi 3-1-1 Sachicho, Hitachi-shi, Ibaraki 1 Nuclear Power Division, Hitachi, Ltd. (72) Inventor Saburo Yamazaki 3-2-1 Kochicho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Engineering Co., Ltd. (reference) 2F068 AA28 BB01 BB14 BB23 CC15 DD10 FF12 FF15 FF16 FF25 HH02 KK14 LL24 QQ01 2G047 AA07 AB05 AB07 BB02 BC18 CB02 CB06 DA01 EA10 GB03

Claims (2)

[Claims] 1. A wedge is arranged on a flaw detection surface of a laminated material coated on a base material, a transmitting oscillator and a receiving oscillator are arranged on the wedge, and ultrasonic waves from the transmitting oscillator are transmitted by the transmitting oscillator. In a clad steel bonding material thickness measuring probe that receives by a receiving vibrator and measures the thickness of the bonding material, the transmitting vibrator and the receiving vibrator are efficiently subjected to a transverse wave on the flaw detection surface. While setting and arranging at the angle to be converted,
A probe for measuring the thickness of a clad steel laminated material, wherein a distance between the transducers for transmission and the transducer for reception is smaller than a geometrically obtained interval. 2. A sound insulating plate is provided between the transmitting vibrator and the receiving vibrator, and a distance between probes between the transmitting vibrator and the receiving vibrator is determined by the sound insulating plate. 2. The probe according to claim 1, wherein the distance is larger than an unobstructed approach limit and smaller than a geometrically obtained interval.