JP2001066294A - Ultrasonic flaw detection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high-sensitivity flaw detection and at the same time eliminate the need for generating unneeded echoes by arranging a plurality of vibration elements at a wedge for oblique-angle flaw detection in an array and setting a vibration element opening width being determined by the width and interval of the elements with a specific expression. SOLUTION: Ultrasonic flaw detection is made, for example, by using an oblique- angle array probe 4 with (n) vibration elements 1 being arranged at a constant interval on the inclined surface of a wedge 2, and each element 1 is individually excited by (n) pulsers included in a group of pulsers 5. A vibration element opening width D in the inclination direction of the wedge is set so that an expression can be satisfied by setting the inclination angle of ultrasonic waves on the flaw detection surface of a specimen to α: a refractive angle to θ; a beam distance determined by an oblique angle flaw detection range or the target position of oblique angle flaw detection to L; wavelength in the nominal frequency of the vibration element of ultrasonic waves being propagated in the specimen to λn. Also, in the plurality of elements 1, the excitation timing and the synthesis timing of a reception signal are controlled for each element, thus performing control so that an ultrasonic sound field being formed in the specimen becomes a desired shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method and apparatus for transmitting and receiving ultrasonic waves by arranging a plurality of vibrating elements in an array to detect flaws on an object.

[0002]

2. Description of the Related Art Ultrasonic flaw detection is widely used as a means for non-destructively inspecting a material such as steel or a flaw existing inside a welded portion. The ultrasonic flaw detection method is a method in which an ultrasonic wave is incident from the surface of a subject and an ultrasonic wave reflected from an internal flaw is received to perform an inspection. Conventionally, in ultrasonic testing which has been widely performed, a probe suitable for a flaw detection purpose such as a vertical type or an oblique type is used.
Many are composed of two vibrators.

There is an ultrasonic flaw detection technique using an array-type probe in which a plurality of minute vibration elements are arranged and each of the vibration elements transmits and receives ultrasonic waves. In the ultrasonic flaw detection using this array probe, for example, as shown in JP-A-9-33500 and JP-A-9-292374, the transmission and reception timing of each array element is controlled,
The ultrasonic beam in the subject is focused on a predetermined position (focal position).

[0004]

In the case where the beam path of the ultrasonic wave is large, such as the flaw detection of a thick steel plate, or the ultrasonic flaw detection of a material having a large attenuation of the ultrasonic wave, using the conventionally widely used ultrasonic flaw detection method. When performing the method, there is a problem that the ultrasonic wave reflected from the flaw is weakened due to the spread of the ultrasonic beam and the attenuation of the ultrasonic wave in the material, and the flaw detection cannot be performed with a good SN ratio. For this reason, flaw detection is performed using an ultrasonic probe having a large transducer area. However, when transmission and reception are performed by a single transducer as in the conventional type, a transducer that can be driven due to applied voltage and the like is used. There was a limit to the size of
In the case of one vibrator, the sound field in the subject is directly controlled by the size (vibrator area) of the vibrator, and control of the sound field is impossible. On the other hand, when using an array type probe,
The above-mentioned JP-A-9-33500 and JP-A-9-292
As typified by Japanese Patent No. 374, for example, in the invention in which the transmission / reception timing of each array element is controlled to converge the ultrasonic beam, the aim is only to improve the detection accuracy at or near the focal position of the ultrasonic beam. It was.

In the case of the ultrasonic flaw detection method in which the beam path of the ultrasonic wave is large or the attenuation of the ultrasonic wave in the subject is large, it is generally better to increase the area of the vibrator or the opening width of the vibrator. However, since it is not clear how much the beam path required to cover the required flaw detection range should be increased, conventionally, trial and error has been repeated. Therefore, a rational standard for the transducer area and the transducer aperture width required for performing ultrasonic inspection in a desired beam path has been required. Further, even when the transducer area and the transducer aperture width are increased, it is also demanded to be able to control the spread of the ultrasonic beam in the subject so that flaws in the subject can be accurately detected. Was.

[0006]

According to an ultrasonic flaw detection method according to the first aspect of the present invention, an ultrasonic test is performed by refracting an ultrasonic wave from a flaw detection surface through a wedge for oblique flaw detection. In the ultrasonic flaw detection method, a plurality of vibrating elements are arranged in an array on the inclined surface of the wedge for oblique flaw detection, and a vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the wedge tilt direction. Is the incident angle of the ultrasonic wave on the inspection surface of the subject is α, the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, and the ultrasonic wave propagating in the subject is When the wavelength at the nominal frequency of the vibrating element is λ _n , the setting is made so as to satisfy the following expression (A).

[0007]

(Equation 5)

The ultrasonic flaw detection method according to a second aspect of the present invention is the ultrasonic flaw detection method according to the first aspect, wherein each of the plurality of vibration elements is excited for each of the plurality of vibration elements. The excitation timing is controlled, and when synthesizing the signals received by the plurality of vibrating elements, the synthesizing timing of the received signals for each of the plurality of vibrating elements is controlled to form in the subject. The ultrasonic field to be controlled is controlled to have a desired shape.

According to a third aspect of the present invention, there is provided an ultrasonic flaw detection method for detecting a flaw of an object by vertically irradiating an ultrasonic wave from the flaw detection surface of the object. The vibrating elements are arranged in an array, and the vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the vibrating element arrangement direction is determined by the flaw detection range of the subject or the flaw detection position of interest. Assuming that the depth from the flaw detection surface is d and the wavelength of the ultrasonic wave propagating in the subject at the nominal frequency of the vibration element is λ _n , the following equation (B) is satisfied.

[0010]

(Equation 6)

According to a fourth aspect of the present invention, in the ultrasonic flaw detection method according to the third aspect, when each of the plurality of vibrating elements is excited, each of the plurality of vibrating elements is provided. The excitation timing is controlled, and when synthesizing the signals received by the plurality of vibrating elements, the synthesizing timing of the received signals for each of the plurality of vibrating elements is controlled to form in the subject. The ultrasonic field to be controlled is controlled to have a desired shape.

An ultrasonic flaw detector according to a fifth aspect of the present invention is the ultrasonic flaw detector which flaw-detects an object by refracting an ultrasonic wave from a surface to be inspected through a wedge for oblique flaw detection. A plurality of vibrating elements are arranged in an array on the inclined surface of the oblique flaw detection wedge, and the vibrating element aperture width D determined by the sum of the widths and the intervals of the plurality of vibrating elements in the wedge tilt direction is the object flaw detection surface. Is the incident angle of the ultrasonic wave at α, the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, and the wavelength of the ultrasonic wave propagating in the subject at the nominal frequency of the vibrating element. Let λ _n be the angle beam probe configured to satisfy the following equation (A) and the timing of the excitation pulse supplied to each of the plurality of vibrating elements of the angle beam probe are individually controlled. A plurality of vibrations of the oblique probe The timing for combining a receive signal for each child individually controlled, the one in which the ultrasonic field is formed into a subject and a sound field control means for controlling to a desired shape.

[0013]

(Equation 7)

An ultrasonic flaw detector according to a sixth aspect of the present invention is an ultrasonic flaw detector for detecting an object by vertically irradiating an ultrasonic wave from the object flaw detection surface. The vibrating elements are arranged in an array, and the vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the vibrating element arrangement direction is determined by the flaw detection range of the subject or the flaw detection position of interest. Assuming that the depth from the flaw detection surface is d and the wavelength of the ultrasonic wave propagating in the subject at the nominal frequency of the vibrating element is λ _n , a vertical probe configured to satisfy the following equation (B): The timing of the excitation pulse supplied to each of the plurality of vibration elements of the vertical probe is individually controlled, and the timing of synthesizing the received signals of each of the plurality of vibration elements of the vertical probe is individually controlled. And formed within the subject Sound field control means for controlling the ultrasonic sound field to have a desired shape.

[0015]

(Equation 8)

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 shows an example in which an array probe for oblique flaw detection which is used for both transmission and reception is used. FIG. 1 is a configuration diagram of an ultrasonic flaw detector according to Embodiment 1 of the present invention. In FIG. 1, 1
Is a plurality of n vibrating elements, and here, each vibrating element has a strip shape. And the short side of this strip is wedge 2
Are arranged in an array at regular intervals on the inclined surface of the wedge 2.
Reference numeral 2 denotes a wedge, reference numeral 3 denotes a damper material, and reference numeral 4 denotes an oblique array probe including the above-described 1 to 3. Reference numeral 5 denotes a pulser group, which includes n pulsers that individually excite the plurality of n vibrating elements 1 included in the oblique array probe 4.

Reference numeral 6 denotes a transmission delay time controller, which individually controls each pulser from the controller 9 in response to a trigger pulse input from the data processor 10 so that the excitation timing of each pulser at the time of transmission can be controlled. Includes a plurality of n variable delay time elements for giving the specified delay time. Reference numeral 7 denotes a reception delay time controller, which controls the output of the n vibrating elements 1 at the time of reception so as to control the synthesis timing when synthesizing the received signals by the plurality of n vibrating elements at the time of reception. The control unit 9 includes a plurality of n delay time variable elements for giving n delay times individually specified for each vibration element to the received signal.

Reference numeral 8 denotes a receiver, which combines and inputs each output of the reception delay time controller 7, amplifies a signal in a predetermined band with a predetermined gain, and supplies a detected video signal to the data processing device 10. I do. Reference numeral 9 denotes a control device, which controls transmission and reception of ultrasonic waves to the pulsar group 5 and the receiver 8, and controls each of the n delay time variable elements and reception devices in the transmission delay time controller 6. Each of the n variable delay time elements in the delay time controller 7 is individually controlled so as to have a delay time as instructed by the personal computer 11. Reference numeral 10 denotes a data processing device that outputs a trigger pulse to the transmission delay time controller 6 and performs processing of flaw detection data based on an input signal from the receiver 8. Reference numeral 11 denotes a personal computer, which controls the control device 9 and the data processing device 10. 12 is an ultrasonic wave in the subject, and 13 is the subject.

FIG. 4 is an explanatory diagram of a virtual vibrator opening width during oblique flaw detection according to the present invention. In FIG. 4, a medium A is a wedge (a wedge angle is α), and a medium B is a subject.
Numeral 12 denotes an ultrasonic wave having a constant beam width in the medium B. The traveling direction of the ultrasonic wave is from the medium A in the opposite direction to the medium B to the medium B.
To the direction to. When the propagation speed of the ultrasonic wave is different between the medium A and the medium B, at the interface between the medium A and the medium B,
Refraction occurs according to Snell's law. Now, assuming that refraction does not occur at this boundary surface, the beam of the ultrasonic wave 12 that has traveled straight from the medium B to the medium A over the range from the point P 'to the point Q' of the boundary surface is shifted from the point P on the wedge inclined surface. The point Q range is reached. Now, assuming that a single vibrator is provided between the point P and the point Q on the wedge inclined surface, the distance between the point P and the point Q (namely, the vibrator aperture width) is D. When the ultrasonic wave from the vibrator is actually refracted from the medium A and enters the medium B, the incident angle is α (equal to the wedge angle α), and the refraction angle is θ.

Now, a perpendicular line is drawn from the point P so as to intersect at right angles with a straight line passing through the points Q to Q '.
The distance between the point P and the point R is D '. This D '
In FIG. 4, the actual transducer aperture width D is the beam width projected on a plane (wavefront) perpendicular to the ultrasonic wave propagation direction when the ultrasonic waves are considered to travel straight through the media A and B. In the present invention, this is referred to as a virtual vibrator aperture width. The virtual oscillator aperture width D 'is the wedge angle (that is, the incident angle of the medium A).
Let α be the refraction angle of the medium B and θ be the refraction angle of the medium B, with reference to the right triangle PQR in FIG. D ′ = Dcos (θ−α) (1) The above D ′ is obtained by using an oblique angle probe having an incident angle α, a refraction angle θ, and a transducer opening width D on a wedge inclined surface. Dcosθ / cos, which is the actual ultrasonic beam width in the medium B
Note that this is different from α.

Next, a reference formula for defining the vibrating element opening width in the present invention (the vibrating element opening width because a plurality of vibrating elements are used in the present invention, but the vibrator opening width in the case of a single vibrator). explain. At present, ultrasonic probes called a focusing type such as a line focusing and a point focusing are commercially available, and these probes are provided with a one-dimensional or two-dimensional curvature directly on a transducer, or with a transducer. The ultrasonic wave is focused by providing an acoustic lens on the acoustic radiating surface of. For general-focusing probe, the focusing effect is obtained is said to be within the near field limit distance of the probe, a circular vibrator, near field limit distance x ₀ is It is expressed by the following equation (2). x ₀ = D ² / 4λ = D ² f / 4C (2) where D, λ, f, and C are as follows. D: diameter of circular oscillator λ: wavelength of ultrasonic wave in propagation medium f: frequency of ultrasonic wave in propagation medium C: velocity of ultrasonic wave in propagation medium

Further, since the focusing effect is obtained, that is, the sound field can be controlled within the short-range sound field limit distance of the vibrator, the oblique flaw detection range or the oblique flaw detection target position Let L be the beam path determined by
Is given by the following equation (3). L ≦ x ₀ (3) In the present invention, the virtual vibration element opening width D ′ represented by the above equation (1) is used instead of the diameter D of the circular vibrator in the above equation (2). Think. When the expressions (1) to (3) are put together and arranged, a result as shown in the following expression (4) is obtained.

[0023]

(Equation 9)

However, L in equation (4) does not include the parameter of the transmission distance in the wedge, but if this parameter is, for example, k, equation (3) becomes the following equation (3 '). . L + k ≦ x ₀ (3 ′) Using the expression (3 ′), the expression (4) becomes the following expression (4 ′).

[0025]

(Equation 10)

Therefore, even if L is used instead of (L + k), the essential meaning of equation (4) does not change. In the case of the vertical flaw detection described in the second embodiment instead of the oblique flaw detection, θ = α = 0 may be set in Expression (4).

An ultrasonic flaw detection operation using the oblique probe 4 in which a plurality of n vibrating elements 1 are arranged in an array as shown in FIG. 1 will be described. First, the dimensions of the strip-shaped vibrator 1 in FIG. 1 are increased, or the number n of simultaneously driven elements is increased to increase the area of the entire probe. In this case, the illustrated vibrating element opening width D is as follows. According to the standards. In other words, the vibration element opening width D determined by the sum of the width of each of the plurality of n vibration elements in the wedge tilt direction (the width of the short side of the strip-shaped vibration element 1) and the interval is such that the wedge angle is α and the object 13 enters the subject 13. Assuming that the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, and the wavelength at the nominal frequency of the ultrasonic vibration element propagating in the subject is λ _n , Selection is made so as to satisfy the above equation (4).

When the aperture width D of the vibrating element is determined so as to satisfy the equation (4), and the oblique array probe 4 having the aperture width D is manufactured, the personal computer 11 starts the oblique array probe. When performing flaw detection using the probe 4, in order to improve the flaw detection sensitivity, detection resolution, and the like, an ultrasonic sound field formed in the subject 13 is focused so as to have a desired shape by focusing. Each delay time to be given to each of the delay time variable elements in the delay time controller 6 and the reception delay time controller 7 is calculated in advance, and the calculated delay time is given to the control device 9 as sound field control data. As a preferable focused sound field in the subject 13, the length and shortness of the beam path required to cover the oblique flaw detection range, the known flaw detection position (distance from the vibration element),
Depending on unknowns, there are cases where the ultrasonic beam is focused relatively slowly (the ultrasonic beam is not narrowed down too much), and cases where the ultrasonic beam is narrowed down considerably to reduce the beam diameter at the desired flaw detection position. An ultrasonic field having a desired shape is appropriately selected based on the above.

Based on sound field control data supplied in advance from the personal computer 11, the control device 9 provides n individual delay times to the input trigger pulse when transmitting ultrasonic waves. Are controlled according to the designated sound field control data. As a result, the respective excitation timings of the n vibrating elements 1 excited by the respective pulsars in the pulsar group 5 are controlled, and a desired transmission sound field is formed. Further, the control device 9
At the time of the ultrasonic wave reception, for each of the delay time variable elements in the reception delay time controller 7 for giving an individual delay time to each of the reception signals of the n vibrating elements 1 according to the designated sound field data. Control each delay time. The n delayed reception signals output from the reception delay time controller 7 are combined on the output side and supplied to the receiver 8. In this way, the synthesis timing of the received signals for each of the n vibrating elements is controlled, and a desired received sound field is formed.

[0030] In the receiver 8, with respect to the synthetic input signal, the equation (4) after amplification with a predetermined gain a signal of a predetermined frequency band having a center frequency wavelength lambda _n of the detection and data processing unit video signal Supply 10 The data processor 10 extracts flaw data from the input video signal,
Processing such as calculation of a flaw position and size is performed, and the processing result is notified to the personal computer 11. The personal computer 11 displays the notification information on a display (not shown) or outputs the notification information to a printer or a recorder.

As described above, in the first embodiment shown in FIG. 1, the element dimensions and the number of array elements of the plurality of n elements arranged in an array on the wedge inclined surface so as to satisfy the opening width of the element of the above formula (4) are satisfied. By increasing the diameter, it is possible to perform high-sensitivity flaw detection even when the path of the ultrasonic beam is large, such as flaw detection of a thick steel plate, or when flaw detection is performed on a material having a large attenuation of ultrasonic waves.
Note that the dimensions of the plurality of n vibrating elements may or may not be the same. Further, by controlling the pulse excitation timing of the plurality of n vibrating elements and the waveform synthesis timing of the received signal to control the spread of the ultrasonic beam in the subject, generation of unnecessary echoes due to the spread of the ultrasonic waves. Is suppressed, and a defective portion can be detected with high accuracy.

FIG. 2 is a diagram showing an example of an ultrasonic probe different from FIG. 1 according to the first embodiment of the present invention. FIG. 2 shows a square or rectangular vibrating element arranged in a matrix (two-dimensionally) in the row and column directions instead of the strip-shaped vibrating element 1 of FIG. In this matrix arrangement, it is easy to adjust both the vibration element opening width and the entire vibration element area (by adjusting D and W in the drawing). Further, in the ultrasonic probe of FIG. 1, the beam focusing is controlled only in the one-dimensional direction of the wedge tilt direction, but in the ultrasonic probe of FIG. 2, the beam focusing is controlled in the wedge tilt direction and the direction perpendicular thereto. Can be controlled in two-dimensional directions.

Embodiment 2 In Embodiment 2, an example is shown in which an array probe for vertical flaw detection which is used for both transmission and reception is used. FIG. 3 is a configuration diagram of an ultrasonic flaw detector according to Embodiment 2 of the present invention. FIG. 3 differs from FIG. 1 only in that a vertical array probe 4A is used instead of the oblique array probe 4 in FIG. 1, and the other configuration is the same as that in FIG.

In the case of the vertical flaw detection shown in FIG. 3, the beam path L determined by the oblique flaw detection range or the target position of the oblique flaw detection is determined by the depth from the flaw detection surface determined by the flaw detection range or the target flaw detection position. Since the incident angle α and the refraction angle θ of the ultrasonic wave are both 0, the vibrating element aperture width D determined by the sum of the widths and the intervals of the short sides of the rectangular vibrator 1 Assuming that the wavelength of the ultrasonic wave propagating through is λ, the selection may be made to satisfy the following equation (5).

[0035]

[Equation 11]

Other structures, operations and effects are the same as those in FIG. Also in the case of vertical flaw detection, beam control in two-dimensional directions can be performed using a matrix probe in which vibrating elements are two-dimensionally arranged.

Next, the results of the oblique flaw detection test performed by the ultrasonic flaw detector shown in FIG. 1 will be described. Here, as a test piece, a steel block having a thickness of 120 mm was placed at a depth of 100 m from the flaw detection surface.
The results of the oblique flaw detection test using a test piece in which a φ3 mm horizontal drill hole was machined at the position of m are shown. In this test, a transverse wave was introduced into the test piece using a wedge as in the case of ordinary angle beam testing, and a vibration element having a nominal frequency of 5 MHz was used. The wedge was made of polystyrene, and the wedge angle was 42.7 ° such that the refraction angle in the test piece was 70 °.

FIG. 5 shows that the opening width D of the vibration element is changed.
The above with and without the focus control of the ultrasonic sound field
It is a figure which shows the example of a measurement of the beam spread in a test piece side hole.
In this case, depending on the oblique flaw detection range or the target position for bevel flaw detection.
The determined beam path L is directed to the flaw position.
And L = 100 mm / cos 70 ° ≒ 292 mm,
Assuming that the shear wave velocity in the test piece is 3230 m / s, the nominal
Ultrasonic wavelength λ at wavenumber_n Is 0.65 mm. This
Their L = 292 mm, λ_n = 0.65mm, α = 4
2.7 °, minimum required calculated using θ = 70 °
Opening width D is D _min Then D_min Is based on equation (4)
Then, it is obtained as in the following equation (6). Also, the flaw detection range
When the entire test piece is used, L = 120 mm / cos 70
° ≒ 351 mm, D_min Is based on equation (4)
It is obtained as in equation (7).

[0039]

(Equation 12)

In FIG. 5, the horizontal axis represents the value D / D obtained by dividing the vibration element opening width D determined by the sum of the widths and intervals of the plurality of vibration elements in the wedge inclination direction by D _min in the above equation (6).
The D _{mi n,} and the vertical axis the echo peak of the transverse hole in each condition 0d
The beam width Wb-6 _dB of _-6 dB when B is
_The value Wb _{-6 dB} / D _min divided by _min is shown. The black circles in the figure indicate the case where the sound field control is performed, and the white circles indicate the case where the sound field control is not performed. According to FIG. 5, when D / D _min is 1 or less, that is, when the vibration element opening width D is smaller than D _min , Wb
_-6dB / _Dmin is large and the beam width is wide. In addition, there is no difference in beam width depending on the presence or absence of the sound field control, which indicates that the sound field control is not effective. On the other hand, when D / D _min is greater than 1, the beam width becomes narrower with sound field control, and the beam width becomes wider without sound field control. is there. Therefore, when performing sound field control,
It is necessary to set the vibration element opening width D so as to satisfy Expression (4).

Next, the test piece (on a steel block having a thickness of 120 mm, a φ3 mm
Of the vibrating element is set to D = 80 mm, which sufficiently satisfies the value of the above equation (6) or (7), and the refraction angle in the test piece is 7
0 °, the nominal frequency of the vibrating element is 5 MHz, and a transverse wave is incident. The wedge is made of polystyrene, and the wedge angle is 42.7 ° so that the refraction angle becomes 70 ° in the test piece. Table 1 shows the results of flaw detection when used.
Table 1 shows that, for (1) the case where the convergence control of the sound field is performed, (2) the case where the sound field is not controlled, and (3) the case where the transducer size is 10 mm × 10 mm which is conventionally widely used, the echo height peak is compared. The scanning distance in the front-back direction at which the echo height is -6 dB and the SN ratio when the peak echo height is 80% are shown.

[0042]

[Table 1]

It can be seen from Table 1 that the SN ratio is considerably improved by increasing the aperture width of the vibrating element and increasing the energy of incident ultrasonic waves by using an array probe as compared with the conventional method. Also, by controlling the sound field, the spread of the ultrasonic wave is suppressed, so that the generation of unnecessary echoes due to the spread of the ultrasonic wave is suppressed, and further, the echo peak position caused by the ultrasonic beam becoming too wide. A decrease in detection accuracy can be prevented, and accurate flaw detection can be realized.

[0044]

As described above, according to the present invention, there is provided an ultrasonic flaw detection method and apparatus for refracting ultrasonic waves from a flaw detection surface through a wedge for oblique flaw detection to detect a flaw in a subject. A plurality of vibrating elements are arranged in an array on the inclined surface of the oblique flaw detection wedge, and the vibrating element opening width D determined by the sum of the width and the interval of each of the plurality of vibrating elements in the wedge tilt direction is the object inspection flaw. The incident angle of the ultrasonic wave on the surface is α, the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, at the nominal frequency of the vibration element of the ultrasonic wave propagating in the subject Wavelength λ _n
Then, setting is made so as to satisfy the following equation (A).
Even in the case of oblique flaw detection where the beam path becomes large with a thick plate or the attenuation of ultrasonic waves in the subject becomes large, high-sensitivity flaw detection becomes possible with a good SN ratio.

[0045]

(Equation 13)

According to the present invention, in the oblique flaw detection, when exciting each of the plurality of vibration elements, the excitation timing is controlled for each of the plurality of vibration elements,
Further, when synthesizing the signals received by each of the plurality of vibrating elements, it controls the synthesizing timing of the received signals for each of the plurality of vibrating elements to generate an ultrasonic sound field formed in the subject. Since control is performed so as to obtain a desired shape, generation of unnecessary echoes due to the spread of ultrasonic waves is suppressed, and accurate detection of a defective portion becomes possible.

According to the present invention, in the ultrasonic flaw detection method and apparatus for detecting a flaw of an object by vertically irradiating an ultrasonic wave from the flaw detection surface of the object, a plurality of vibrating elements are arrayed on the flaw detection surface of the object. The vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the vibrating element arrangement direction is determined from the flaw detection range of the subject or the flaw detection surface determined by the flaw detection position of interest. Is defined as d and the wavelength of the ultrasonic wave propagating in the subject at the nominal frequency of the vibrating element as λ _n , the following formula (B) is satisfied. Also in a vertical flaw detection in a case or when the attenuation of the ultrasonic wave in the subject becomes large, a high sensitivity flaw detection becomes possible with a good SN ratio.

[0048]

[Equation 14]

According to the present invention, in the vertical flaw detection, when exciting each of the plurality of vibration elements, the excitation timing is controlled for each of the plurality of vibration elements,
Further, when synthesizing the signals received by each of the plurality of vibrating elements, it controls the synthesizing timing of the received signals for each of the plurality of vibrating elements to generate an ultrasonic sound field formed in the subject. Since control is performed so as to obtain a desired shape, generation of unnecessary echoes due to the spread of ultrasonic waves is suppressed, and accurate detection of a defective portion becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an example of an ultrasonic probe different from FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of an ultrasonic flaw detector according to Embodiment 2 of the present invention.

FIG. 4 is an explanatory diagram of a virtual vibrator opening width during oblique flaw detection according to the present invention.

FIG. 5 is a diagram showing an example of measuring the spread of an ultrasonic beam in a case where the aperture width of a vibrating element is changed and convergence control is performed on an ultrasonic sound field.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration element 2 Wedge 3 Damper material 4 Angled array probe 4A Vertical array probe 5 Pulser group 6 Transmission delay time controller 7 Reception delay time controller 8 Receiver 9 Control device 10 Data processing device 11 Personal computer

Claims (6)

[Claims] 1. An ultrasonic flaw detection method in which ultrasonic waves are refracted from a flaw detection surface of an object via a wedge for flaw detection to perform flaw detection on the object, wherein a plurality of vibrations are formed on an inclined surface of the wedge for the flaw detection. The elements are arranged in an array, and a vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the wedge tilt direction.
Is the incident angle of the ultrasonic wave on the inspection surface of the subject is α, the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, and the ultrasonic wave propagating in the subject is An ultrasonic flaw detection method characterized by setting the wavelength at a nominal frequency of a vibrating element to be λ _n so as to satisfy the following expression (A). (Equation 1) 2. When exciting each of the plurality of vibrating elements, controlling excitation timing of each of the plurality of vibrating elements, and synthesizing signals received by each of the plurality of vibrating elements. 2. The method according to claim 1, further comprising: controlling a synthesis timing of a received signal for each of the plurality of vibrating elements so as to control an ultrasonic sound field formed in the subject to have a desired shape. The described ultrasonic flaw detection method. 3. Ultrasonic waves are perpendicularly incident from a flaw detection surface of an object.
In the ultrasonic flaw detection method for flaw detection of a subject, a plurality of vibrating elements are arranged in an array on the flaw detection surface of the subject.
And a plurality of the vibrating elements in the vibrating element array direction.
The vibration element opening width D, which is determined by the sum of the width and the interval,
Determined by the flaw detection area of the specimen or the flaw detection position of interest
The ultrasonic wave propagating in the subject, where d is the depth from the inspection surface
Wavelength at the nominal frequency of the vibrating element _n Then
The setting is made so as to satisfy the following equation (B).
Ultrasonic flaw detection method. (Equation 2) 4. When exciting each of the plurality of vibrating elements, controlling the excitation timing of each of the plurality of vibrating elements, and synthesizing signals received by the plurality of vibrating elements, respectively. 4. The method according to claim 3, further comprising: controlling a synthesis timing of a received signal for each of the plurality of vibrating elements to control an ultrasonic sound field formed in the subject to have a desired shape. The described ultrasonic flaw detection method. 5. An ultrasonic flaw detector for detecting a subject by refracting ultrasonic waves from a flaw detection surface through a wedge for bevel flaw detection, wherein a plurality of vibrations are formed on an inclined surface of the wedge for bevel flaw detection. The elements are arranged in an array, and a vibrating element opening width D determined by the sum of the widths and intervals of the plurality of vibrating elements in the wedge tilt direction.
Is the incident angle of the ultrasonic wave on the inspection surface of the subject is α, the refraction angle is θ, the beam path determined by the oblique flaw detection range or the target position of the oblique flaw detection is L, and the ultrasonic wave propagating in the subject is Assuming that the wavelength at the nominal frequency of the vibrating element is λ _n , an oblique probe configured to satisfy the following expression (A), and an excitation pulse supplied to each of the plurality of vibrating elements of the oblique probe Individually controlling the timing of combining the received signals of the plurality of vibrating elements of the oblique probe, and controlling the ultrasonic sound field formed in the subject. An ultrasonic flaw detector comprising: a sound field control means for controlling a shape of the ultrasonic flaw. (Equation 3) 6. An ultrasonic wave is vertically incident on a flaw detection surface of an object.
An ultrasonic flaw detector that performs flaw detection of a subject by arranging a plurality of vibrating elements in an array on the flaw detection surface of the subject.
And a plurality of the vibrating elements in the vibrating element array direction.
The vibration element opening width D, which is determined by the sum of the width and the interval,
Determined by the flaw detection area of the specimen or the flaw detection position of interest
The ultrasonic wave propagating in the subject, where d is the depth from the inspection surface
Wavelength at the nominal frequency of the vibrating element _n Then
A vertical probe configured to satisfy the following expression (B); and an excitation pad supplied to each of a plurality of vibrating elements of the vertical probe.
The timing of the lus individually and the vertical probe
For synthesizing the received signals for each of the multiple vibrating elements
Are individually controlled, and an ultrasonic sound field formed in the subject
Sound field control means for controlling the sound to a desired shape.
An ultrasonic flaw detector characterized by the following. (Equation 4)