JP2000275224A - Ultrasonic flaw detecting device and ultrasonic flow detecting method for thin metal member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply measure the depth of a flaw section existing on a thin metal at a low cost by utilizing the conventional ultrasonic flaw detection technique. SOLUTION: A pulse generator 5 generating a pulse voltage is connected to a plate wave probe 2, the pulse voltage generated by the pulse generator 5 is fed to the piezoelectric element 2a of the plate wave probe 2, then the piezoelectric element 2a is vibrated to generate pulse waves, i.e., ultrasonic waves. A flaw depth calculating means 6 is connected to a transversal wave angle beam probe 3, and the received transversal wave is converted into an electric signal by its piezoelectric element 3a and is fed to a flaw depth calculating means 6 from the transversal wave angle beam probe 3. The reception intensity of the received transversal wave (height of the received echo) is detected by the flaw depth calculating means 6 based on the electric signal fed from the transversal wave angle beam probe 3, and the depth of a flaw section (the length of a crack in the thickness direction of a steel sheet) is calculated from the reception intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detecting apparatus for a metal thin member for inspecting a defect existing in a thin member made of a thin metal plate such as stainless steel, and an ultrasonic flaw detecting method therefor.

[0002]

2. Description of the Related Art Conventionally, as a method of inspecting a defective portion existing on the surface of a thin metal member, a visual inspection and a penetrating flaw detection for detecting a defective portion into an image which can be easily seen with the naked eye utilizing a capillary phenomenon are known. The inspected member where the defect was found was usually discarded. However, even if a defective portion is found, if it is possible to determine whether or not the defective portion adversely affects the function of the object to be inspected, it is not necessary to abandon all products. In this case, as one method for determining whether or not the function of the inspection object is adversely affected, it is conceivable to measure the depth of the defective portion and compare the measured depth with a reference value. As a method for measuring the depth of the defect, an electric resistance method is widely used.

On the other hand, an ultrasonic flaw detection method is suitable for flaw detection of a defective portion of a thin metal member such as a metal thin plate (the thickness of which is several times or less the ultrasonic wavelength). In the ultrasonic flaw detection method, a so-called plate wave type flaw detection apparatus is used. In this case, the ultrasonic wave generated by the probe is obliquely incident on the plate to generate a plate wave, and the plate wave is reflected by the defective portion, and the plate wave is reflected and returned to perform flaw detection. . For example,
Japanese Patent Application Laid-Open No. 8-248008 discloses an ultrasonic flaw detector capable of detecting a minute defect having a diameter of about 0.1 mm. (Echo level) is also disclosed.

[0004]

In the measurement of the depth of a defective portion by the electric resistance method, it is difficult to theoretically obtain a depth judgment curve. Therefore, a test piece having an artificially formed defective portion is actually measured. As a result, a depth determination curve is obtained in advance. However, since measured values such as apparent resistivity are affected by the length and width of the defect, and the thickness and curvature of the member to be inspected, skill and labor are required to determine the depth determination curve and determine the depth. Is done. Further, it is difficult to secure measurement accuracy on the order of 0.1 mm, and it was virtually impossible to accurately measure the depth of a defective portion using an electric resistance method.

In the ultrasonic flaw detector disclosed in Japanese Patent Application Laid-Open No. 8-248008, although there is a suggestion regarding the volume of a defect, no suggestion is made regarding the depth of the defect. There has been no effective apparatus and method for measuring the depth of a defect in the ultrasonic testing technique.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and uses a conventional ultrasonic testing technique to easily and inexpensively measure the depth of a defect existing in a thin metal member. It is an object of the present invention to provide an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method capable of performing the above-mentioned operations.

[0007]

As a result of experimental research, the present inventors have found that a sheet wave is generated by ultrasonic waves on a thin metal member such as a thin metal plate (the thickness of which is several times or less the ultrasonic wavelength). A new finding is that the reception intensity of the transverse wave component of the plate wave reflected from the defective portion and the depth of the defective portion are substantially proportional to each other. The present invention has been made based on the relationship between the reception intensity of the shear wave component of the plate wave reflected from the newly found defect and the depth of the defect.

According to a first aspect of the present invention, there is provided a plate wave generating means for generating ultrasonic waves obliquely on a thin metal member and generating a plate wave on the thin metal member, and an ultrasonic wave reflected from a defective portion of the thin metal member. And a defect depth calculating means for calculating the depth of the defective portion based on the reception intensity of the shear wave received by the shear wave receiving means.

According to the ultrasonic inspection apparatus for a thin metal member according to the first aspect, the relationship between the reception intensity of the transverse wave component of the plate wave reflected from the newly found defect and the depth of the defect. Based on the above, it is possible to measure the depth of a defect existing in an inexpensive and simple metal thin member using an ultrasonic flaw detection technique conventionally used.

According to a second aspect of the present invention, in the first aspect of the present invention, the defect depth calculating means stores a correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion, which is obtained in advance. Means for calculating the depth of the defective portion from the reception intensity of the shear wave, based on the correlation characteristics stored in the storage means. In this case, since the storage means for storing the correlation characteristic between the received strength of the transverse wave and the depth of the defective portion, which has been obtained in advance, is stored in the storage means as soon as the received received strength is detected. It is possible to calculate the depth of the defective portion of the inspected member based on the previously obtained correlation characteristic between the received strength of the shear wave and the depth of the defective portion.

According to a third aspect of the present invention, there is provided a plate wave generating means for receiving a pulse voltage from the pulse generating means and obliquely applying ultrasonic waves to the thin metal member to generate a plate wave on the thin metal member. A probe, a shear wave oblique probe that receives only the shear wave of the ultrasonic wave reflected from the defective portion of the thin metal member, and a reception that detects the reception intensity of the shear wave received by the shear wave bevel probe Intensity detecting means, storing means for storing correlation characteristics between the received intensity of the shear wave and the depth of the defect determined in advance, and correlation between the received intensity of the shear wave detected by the received intensity detecting means and the storage means Defect depth calculating means for calculating the depth of the defective portion based on the characteristics.

According to the ultrasonic inspection apparatus for a thin metal member according to the third aspect, the depth of the defect existing in the thin metal member can be reduced by utilizing the conventionally used ultrasonic inspection technique. And it is possible to easily measure it, and has storage means for storing the correlation characteristic between the received intensity of the shear wave and the depth of the defect, which is obtained in advance. As soon as it is detected, the depth of the defective portion of the inspected member is determined based on the correlation characteristic between the previously obtained shear wave reception intensity stored in the storage means and the depth of the defective portion and the received shear wave reception intensity. Can be calculated.

According to a fourth aspect of the present invention, an ultrasonic wave is obliquely incident on a thin metal member having a defective portion to generate a plate wave, and a transverse wave of the ultrasonic wave reflected from the defective portion is received and received. It is characterized in that the receiving strength of the shear wave is detected, and the depth of the defective portion is calculated based on the detected receiving strength of the shear wave.

According to the ultrasonic inspection method for a thin metal member according to the fourth aspect, the relationship between the reception intensity of the transverse wave component of the plate wave reflected from the newly found defect and the depth of the defect. Based on the above, it is possible to measure the depth of a defect existing in an inexpensive and simple metal thin member using an ultrasonic flaw detection technique conventionally used.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, when calculating the depth of the defective portion based on the received intensity of the received transverse wave, the received intensity of the transverse wave determined in advance is used. The depth of the defective portion is calculated based on the correlation characteristic between the defect and the depth of the defective portion, and the reception intensity of the received shear wave. In this case, since the correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion is obtained in advance, when the reception intensity of the received shear wave is detected, the reception intensity of the previously obtained shear wave and the defective portion are immediately detected. It is possible to calculate the depth of the defect portion of the inspected member based on the correlation characteristic with the depth and the received strength of the received transverse wave.

According to a sixth aspect of the present invention, in the invention according to the fifth aspect, the correlation characteristic between the receiving intensity of the shear wave and the depth of the defective portion is determined by a slit-shaped defective portion having a predetermined depth in the thin metal member. The ultrasonic wave is obliquely incident on the thin metal member on which the slit-shaped defect is formed to generate a plate wave, and only the ultrasonic transverse wave reflected from the defect is received, and the received transverse wave is received. It is characterized in that the intensity is detected, the predetermined depth of the slit-shaped defect portion is changed, the reception intensity of the shear wave is repeatedly detected, and the reception intensity is determined from the reception intensity of each slit-shaped defect portion having a different depth. In this case, it is possible to appropriately obtain the correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion in advance.

[0017]

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

FIGS. 1 to 5 show a first embodiment of an ultrasonic flaw detector according to the present invention. In the first embodiment, FIGS. 1 and 2 schematically show the entire configuration. A plate wave probe 2 and a shear wave oblique angle probe 3 are placed on a stainless steel plate 1 having a thickness of 2 mm, which is a member to be inspected. The steel plate 1 has a crack 4 opened as a defect 4 on the surface of the steel plate 1. In this case, the presence of the defective portion 4 is confirmed in advance by another inspection method such as a visual inspection, and the position of the defective portion 4 is also specified.

The plate wave probe 2 has a piezoelectric element 2a, and is configured so that ultrasonic waves generated by the piezoelectric element 2a are obliquely incident on the steel plate 1 and generate a plate wave on the steel plate 1. I have.
The shear wave oblique probe 3 has a piezoelectric element 3a, and is configured to selectively receive only the shear wave component of the plate wave reflected by the defective portion 4. For example, frequency 5 MHz, refraction angle 6
0 °. That is, the shear wave oblique angle probe 3 includes:
The angle is set so that the piezoelectric element 3a can receive a transverse wave having an appropriate refraction angle. The plate wave probe 2 and the shear wave oblique probe 3 are such that a plate wave emitted from the plate wave probe 2 is reflected at the defect portion 4 and a plate wave reflected at the defect portion 4 is a shear wave oblique angle. The probe 3 is arranged at a predetermined angle with respect to the defective portion 4 so that the probe 3 can receive the signal. When mounting the plate wave probe 2 and the shear wave oblique probe 3 on the steel plate 1, oil, water, glycerin, etc. are applied on the steel plate 1 and the probes 2, 3 and the steel plate 1 are applied. Ultrasonic waves are easily passed between the two. FIG. 2 shows only the shear wave oblique probe 3 side.

A pulse generator 5 for generating a pulse voltage is connected to the plate wave probe 2. By sending the pulse voltage generated by the pulse generator 5 to the piezoelectric element 2a of the plate wave probe 2, the piezoelectric element 2a vibrates, and the plate wave probe 2 generates a pulse wave, that is, an ultrasonic wave. become. The shear wave oblique angle probe 3 is connected to a defect depth calculating means 6. The received shear wave is converted into an electric signal by the piezoelectric element 3 a and sent from the shear wave oblique probe 3 to the defect depth calculating means 6. The defect depth calculating means 6 detects the reception intensity of the received shear wave (the height of the received echo) based on the electric signal sent from the shear wave oblique probe 3, and detects the depth of the defect portion 4 from the received intensity. The thickness (the length of the crack in the thickness direction of the steel sheet) is calculated.
The monitor 7 is connected to the defect depth calculating means 6. The monitor 7 displays the calculated depth of the defective portion 4 and the waveform of the received shear wave, as shown in FIG. Here, the depth of the defective portion 4 represents the ratio of the depth of the defective portion 4 to the thickness of the steel sheet 1 in percentage (% t).

Next, a method of calculating the depth of the defective portion 4 will be described. The defect depth calculation means 6 has a storage means 8, and the storage means 8 stores the reception intensity of the received transverse wave (the height of the received echo) and the depth of the defect as shown in FIG. Correlation characteristics are stored. Therefore, by detecting the reception intensity of the received shear wave based on the electric signal sent from the shear wave oblique probe 3, and comparing the detected reception intensity of the shear wave with the correlation characteristic stored in the storage means 8, The depth of the defect 4 can be calculated. Here, the reception intensity of the shear wave (height of the received echo) is the pulse height of the received shear wave (echo height) with respect to the pulse height of the pulse wave (ultrasonic wave) generated by the plate wave probe 2. Is expressed as a percentage (%).

The correlation characteristic between the reception intensity of the received transverse wave and the depth of the defect as shown in FIG. 4 is obtained as follows. As shown in FIG. 5, a test slit 12 (test defect portion) having a predetermined depth is formed artificially (experimentally) as a defect portion in a test steel plate (test metal thin-walled member) 11, and FIGS. The reception intensity of the shear wave is measured by the ultrasonic flaw detector shown in FIG. The depth of the test slit 12 is changed, the measurement is repeated a plurality of times, and a correlation characteristic between the reception intensity of the received shear wave and the test slit 12, that is, the depth of the test defect portion is obtained from the measurement result. Since this characteristic is affected by the thickness and the material of the object to be inspected, it is most preferable to form a test slit 12 in a test steel plate 11 having the same thickness and material as the member to be inspected, and to perform measurement. In FIG. 5, only the shear wave oblique probe 3 side is shown.

Since the depth of the defective portion 4 which has been difficult to measure up to now can be measured using the conventional ultrasonic flaw detection technique, an inexpensive and simple ultrasonic flaw detector can be used. And an ultrasonic flaw detection method can be provided. In addition, since the storage means 8 for storing the correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion, which has been obtained in advance, is stored in the storage means 8 as soon as the received reception intensity is detected. The depth of the defective portion 4 can be calculated based on the correlation characteristic between the received strength of the shear wave and the depth of the defective portion, which is obtained in advance. Therefore,
The depth of the defective portion 4 can be quickly measured.

Further, the depth of the test slit 12 artificially formed in the test steel plate 11 is changed, and the measurement is repeated a plurality of times. From the measurement result, the correlation characteristic between the reception intensity of the received shear wave and the depth of the defect is obtained. Is obtained, the correlation characteristic can be appropriately set, and the accuracy of measuring the depth of the defective portion 4 can be improved.

In the first embodiment, the depth of the defective portion 4 existing in the steel plate 1 is measured. However, this ultrasonic flaw detector can detect the defective portion of a thin metal member having a curved portion such as a bellows. The depth is possible, and is particularly suitable for measuring the depth of a defect existing in a curved portion such as a bellows.

FIGS. 6 and 7 show a second embodiment of the ultrasonic flaw detector according to the present invention. FIG. 6 is a perspective view of the integrated ultrasonic probe according to the second embodiment. FIG. 7 is a partial cross-sectional view of the integrated ultrasonic probe according to the second embodiment.

The ultrasonic flaw detector shown in FIGS. 1 and 2 is provided with the plate wave probe 2 and the shear wave oblique probe 3 separately, but the ultrasonic wave flaw detector shown in FIGS. The flaw detector has an integrated ultrasonic probe 21 configured by integrally incorporating a plate wave probe and a shear wave oblique probe into one case 22. The plate wave probe section 23 and the shear wave oblique probe section 24 are separated by an acoustic division surface 25 made of a sound absorbing material such as cork. The plate wave probe unit 23 is provided with a piezoelectric element 23a, and the plate wave probe unit 23 obliquely enters ultrasonic waves generated by the piezoelectric element 23a into a member to be inspected such as a steel plate. The plate member is configured to generate a plate wave. The shear wave oblique probe unit 24 is provided with a piezoelectric element 24a, and the shear wave oblique probe unit 24 is configured to selectively receive only the shear wave component of the plate wave reflected at the defect. I have. That is, the piezoelectric element 24a
The angle is set and arranged so that a transverse wave having an appropriate refraction angle can be received. The two piezoelectric elements 23a and 24a are configured such that the plate wave emitted by the plate wave probe unit 23 is reflected by the defect unit 4, and the plate wave reflected by the defect unit 4 is converted by the shear wave oblique probe unit 2
4 so as to be able to receive the signal at a predetermined angle with respect to the defective portion 4. Further, both piezoelectric elements 23a, 2
4a is connected to the electrodes 23b and 24b, respectively. The electrode 23b is connected to a pulse generator (not shown), and the electrode 24b is connected to a defect depth calculating means (not shown).

In the second embodiment, the ultrasonic flaw detector uses a plate wave probe and a shear wave oblique probe in one case 22.
The ultrasonic flaw detector is mounted on a member to be inspected such as a steel plate having a defective portion, and a pulse is generated with respect to the electrodes 23b and 24b. Since the measurement can be started only by connecting the detector 5 and the defect depth calculating means 6, the operability is excellent and the number of steps for the flaw detection inspection can be reduced. Also, the piezoelectric element 2
If the arrangement structure of 3a and 24a is configured so that it can be appropriately selected and arranged depending on the thickness of a steel plate (member to be inspected) or the like,
While flaw detection can be performed on steel plates of various types and thicknesses, the accuracy of the inspection itself can be improved.

FIG. 8 shows a third embodiment of the ultrasonic flaw detector according to the present invention.
An embodiment will be described. The ultrasonic inspection apparatus according to the third embodiment includes an insertion-type ultrasonic probe 33 for measuring the depth of a defect 32 existing on the inner peripheral surface of a pipe-shaped thin metal member 31.
FIG. 8 is a partial cross-sectional view of the interpolation type ultrasonic probe 33. The defect portion 32 extends in the circumferential direction of the inner peripheral surface of the pipe-shaped thin metal member 31.

The plate wave probe 3 is placed in the cylindrical probe body 34.
5 and a shear wave oblique probe 36 are provided. The plate wave probe 35 and the shear wave oblique probe 36 are arranged in the longitudinal direction of the probe main body 34, and the shear wave oblique probe 36 is connected to the plate wave probe 3.
5 is located forward when viewed in the ultrasonic wave incident direction. This is because the plate wave (transverse wave) reflected at the defective portion 32 is attenuated, so that the shear wave oblique probe 36 is brought closer to the defective portion 32 so as to appropriately receive the reflected plate wave (transverse wave). It is. The plate wave probe 35 and the shear wave oblique probe 36 have a piezoelectric element (not shown) as in the first embodiment. A soft rubber cover 37 is provided on the outer periphery of the portion of the probe body 34 where the plate wave probe 35 and the shear wave oblique probe 36 are provided. Further, the probe main body 3 provided with the plate wave probe 35 and the shear wave oblique angle probe 36 is provided.
4 and the inside of the pipe-shaped thin metal member 31 are filled with an acoustic coupling liquid.

The depth of the defective portion 32 is the same as that described in the first and second embodiments, and a detailed description thereof will be omitted, but only the transverse wave component of the plate wave reflected by the defective portion 32 will be described. It is measured by selectively receiving the shear wave oblique probe 36 and calculating the depth of the defective portion 32 based on the received strength of the received shear wave. Thereby, the defective portion 3 extending in the circumferential direction of the inner peripheral surface of the pipe-shaped thin metal member 31 is present.
2 can be measured. Further, the insertion type ultrasonic probe 3 is gradually increased from the end of the pipe-shaped thin metal member 31.
By inserting 3 and scanning the inner peripheral surface of the thin metal member 31 in the longitudinal direction, the position of the defective portion 32 can be detected at the same time.

It should be noted that the plate wave probe 3
5 and the shear wave oblique probe 36 are disposed along the circumferential direction of the probe main body 34 so as to extend on the inner peripheral surface of the pipe-shaped thin metal member 31 in the longitudinal direction of the thin metal member 31. It is also possible to detect the depth and position of the existing defect.

FIG. 9 shows a fourth embodiment of the ultrasonic flaw detector according to the present invention.
An embodiment will be described. The ultrasonic inspection apparatus according to the fourth embodiment includes an extrapolation type ultrasonic probe 43 for measuring the depth of a defect 42 existing on the outer peripheral surface of a pipe-shaped thin metal member 41.
FIG. 9 is a partial cross-sectional view of the extrapolation type ultrasonic probe 43. The defective portion 42 extends on the outer peripheral surface of the pipe-shaped thin metal member 41 in the longitudinal direction of the thin metal member 41.

The plate wave probe 4 is placed in the cylindrical probe body 44.
5 and a shear wave oblique probe 46 are provided. The plate wave probe 45 and the shear wave oblique probe 46 are arranged in the circumferential direction of the probe main body 44, and the shear wave oblique probe 46 is moved from the plate wave probe 45 in the ultrasonic wave incident direction. It is arranged so that it looks forward. This takes into account the attenuation due to reflection as in the third embodiment. The depth of the defective portion 42 is the same as that of the first to third embodiments, and detailed description is omitted. However, only the shear wave component of the plate wave reflected by the defective portion 42 is selectively applied to the shear wave. The measurement is performed by calculating the depth of the defective portion 42 based on the received intensity of the received transverse wave received by the angular probe 46. Thereby, it is possible to measure the depth of the defective portion 42 which extends on the outer peripheral surface of the pipe-shaped thin metal member 41 in the longitudinal direction of the thin metal member 41.
In addition, if the extrapolation type ultrasonic probe 44 is inserted into the pipe-shaped thin metal member 41 and then rotated to scan the outer peripheral surface of the thin metal member 41, the position of the defective portion 42 can be detected at the same time. It is.

By providing a plate wave probe 45 and a shear wave oblique probe 46 in the probe body 44 along the longitudinal direction of the probe body 44, a pipe-shaped metal thin wall is formed. It is also possible to detect the depth and position of a defective portion extending in the circumferential direction of the outer peripheral surface of the member 41.

[0036]

As described in detail above, claim 1 is as follows.
According to the invention described in (1), the depth of the defect portion, which has been difficult to measure, can be measured using the conventionally used ultrasonic flaw detection technique. Can be provided.

According to the second aspect of the present invention, since the storage means for storing the correlation characteristic between the reception intensity of the shear wave and the depth of the defect previously determined, the reception intensity of the shear wave is detected. Then, the depth of the defective portion can be quickly calculated based on the correlation characteristic between the reception intensity of the transverse wave and the depth of the defective portion, which is stored in advance in the storage means, and the depth of the defective portion can be quickly calculated. Can be provided.

According to the third aspect of the present invention, it is possible to measure the depth of a defective portion, which has been difficult to measure until now, using a conventional ultrasonic testing technique.
Since there is a storage means for storing the correlation characteristic between the received strength of the shear wave and the depth of the defective portion, which has been obtained in advance, when the received strength of the shear wave is detected, it is obtained in advance and immediately stored in the storage means. It is possible to calculate the depth of a defective portion based on the correlation characteristic between the shear wave receiving intensity and the depth of the defective portion. An ultrasonic flaw detector can be provided.

According to the fourth aspect of the present invention, it is possible to measure the depth of a defective portion, which has been difficult to measure until now, using a conventional ultrasonic flaw detection technique. In addition, it is possible to provide a simple ultrasonic inspection method for a thin metal member.

According to the fifth aspect of the present invention, since the correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion is obtained in advance, immediately after the reception intensity of the shear wave is detected, the previously calculated shear wave of the shear wave is detected. It is possible to calculate the depth of a defect based on the correlation characteristic between the reception intensity and the depth of the defect, and to provide an ultrasonic flaw detection method for a thin metal member that can quickly measure the depth of the defect. Becomes

According to the sixth aspect of the present invention, it is possible to appropriately obtain the correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion in advance, thereby improving the accuracy of measuring the depth of the defective portion. It is possible to provide an ultrasonic flaw detection method for a thin metal member which can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention.

FIG. 2 is a configuration diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention.

FIG. 3 is an explanatory diagram illustrating a display screen of a monitor in the first embodiment of the ultrasonic flaw detector according to the present invention.

FIG. 4 is a table illustrating the relationship between the reception intensity (echo height) of a received transverse wave and the depth of a defect.

FIG. 5 is a schematic view showing a first embodiment of an ultrasonic flaw detector according to the present invention.

FIG. 6 is a perspective view of an integrated ultrasonic probe according to a second embodiment of the ultrasonic inspection device according to the present invention.

FIG. 7 is a partial cross-sectional view of an integrated ultrasonic probe, showing a second embodiment of the ultrasonic inspection device according to the present invention.

FIG. 8 is a partial cross-sectional view of an interpolation type ultrasonic probe showing a third embodiment of the ultrasonic inspection device according to the present invention.

FIG. 9 is a partial cross-sectional view of an extrapolation type ultrasonic probe showing a fourth embodiment of the ultrasonic inspection device according to the present invention.

[Explanation of symbols]

1, 11: steel plate, 2, 35, 45: plate wave probe, 3, 3
6, 46 ... shear wave oblique probe, 2a, 3a, 23a, 24
a ... piezoelectric element, 4, 32, 42 ... defect part, 5 ... pulse generator, 6 ... defect depth calculation means, 12 ... slit, 21 ...
Integral ultrasonic probe, 31, 41: thin metal member in the form of a pipe, 33: internal ultrasonic probe, 43: external ultrasonic probe.

Claims (6)

[Claims] 1. A plate wave generating means for obliquely entering an ultrasonic wave into a thin metal member to generate a plate wave in the thin metal member, and receiving a transverse wave of the ultrasonic wave reflected from a defective portion of the thin metal member. An ultrasonic flaw detector for a thin metal member, comprising: a shear wave receiving means; and a defect depth calculating means for calculating a depth of a defective portion based on a reception intensity of the shear wave received by the shear wave receiving means. 2. The defect depth calculation means includes a storage means for storing a correlation characteristic between a reception strength of a transverse wave and a depth of a defect, which is obtained in advance, and the defect depth calculation means stores the correlation characteristic stored in the storage means. 2. The ultrasonic inspection apparatus for a thin metal member according to claim 1, wherein the apparatus is configured to calculate the depth of the defective portion from the reception intensity of the shear wave based on the correlation characteristic. 3. 3. A pulse wave generating means, a plate wave probe receiving a pulse voltage from the pulse generating means, obliquely incident ultrasonic waves on the thin metal member, and generating a plate wave on the thin metal member, A shear wave oblique probe that receives only the shear wave of the ultrasonic wave reflected from the defective portion of the thin metal member, and a reception intensity detection unit that detects the reception intensity of the shear wave received by the shear wave oblique probe Storage means for storing a correlation characteristic between the reception intensity of the shear wave and the depth of the defective portion determined in advance; and the reception intensity of the shear wave detected by the reception intensity detection means and the correlation stored in the storage means. And a defect depth calculating means for calculating the depth of the defective portion based on the characteristic. 4. An ultrasonic wave is obliquely incident on a thin metal member having a defective portion to generate a plate wave, a transverse wave of the ultrasonic wave reflected from the defective portion is received, and a reception intensity of the received transverse wave is reduced. An ultrasonic flaw detection method for a thin metal member, comprising: detecting a depth of the defective portion based on the detected reception intensity of the transverse wave. 5. When calculating the depth of the defective portion, the defect is calculated based on a correlation characteristic between a previously obtained shear wave reception intensity and the depth of the defective portion and the received shear wave reception intensity. The ultrasonic inspection method for a thin metal member according to claim 4, wherein a depth of the portion is calculated. 6. The correlation characteristic between the reception intensity of the shear wave and the depth of a defect portion is obtained by forming a slit-like test defect portion in a test metal thin member, and forming a slit-like test defect portion on the test metal thin member on which the test defect portion is formed. Obliquely incident ultrasonic waves to generate a plate wave, receive only the transverse wave of the ultrasonic wave reflected from the test defect portion, detect the received intensity of the received transverse wave, and change the depth of the test defect portion To repeat the detection of the reception intensity of the shear wave,
The ultrasonic inspection method for a thin metal member according to claim 5, wherein the reception intensity is obtained for each of the test defect portions having different depths.