JP2021032756A - Ultrasonic flaw detector and method, and in-furnace structure preservation method - Google Patents

Abstract

To provide an ultrasonic flaw detection technology with which, when reflecting an ultrasonic wave and having it reach a defect, it is possible to obtain highly reliable test results even when the reflection surface is uneven.SOLUTION: An ultrasonic flaw detector 10 comprises: a transmit/receive unit 11 for transmitting and receiving an ultrasonic wave U to and from each of a plurality of ultrasonic elements 31 arrayed in an array probe 30; a database 12 for holding the shape information 45 of an inspection object 40 a second face 42 of which is formed on a non-continuous plane; a computation unit 16 for computing a propagation time T on the basis of the shape information 45 till the ultrasonic wave U reaches a focus F after being reflected on the second face 42; a calculation unit 17 for calculating a difference between the propagation time T of the ultrasonic element 31 selected for a reference point C and the propagation time T of the other ultrasonic elements 31, as a delay time Δt; and a synthesizing unit 18 for adjusting the timing of transmission and/or reception of the ultrasonic wave U on the basis of the delay time Δt and synthesizing a plurality of echo waveforms 35 received by each ultrasonic element 31.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to an ultrasonic flaw detection technique by a phased array method and a method for maintaining a structure inside a furnace.

Ultrasonic flaw detection test is a technology that can confirm the soundness of the surface and inside of structural materials in a non-destructive manner, and is an indispensable inspection technology in various fields. The phased array type ultrasonic flaw detection test uses a compact array probe in which a plurality of piezoelectric elements for transmitting and receiving ultrasonic waves are arranged. In this phased array method, ultrasonic waves are transmitted from a plurality of piezoelectric elements by shifting the timing (delay time). As a result, ultrasonic waves can be incident in an arbitrary direction and converged at an arbitrary position without moving the array probe.

Further, in the phased array method, ultrasonic waves can be scanned as opposed to the monocular method in which the propagation route of ultrasonic waves is fixed, and a wide range of flaw detection tests can be performed with the probe fixed. As described above, the phased array method can be applied to an inspection target having a complicated shape by controlling the incident beam, and is widely adopted because of its expandability in various points.

Recently, large-scale power plants such as nuclear power and thermal power and social infrastructure equipment are aging. For this reason, the parts to be inspected by ultrasonic flaw detection and the types of defects to be detected are diversified as compared with the conventional ones. Until now, the parts to be inspected were designed for inspection and exposed like welding, so it was easy to access during the ultrasonic flaw detection test.

On the other hand, in a part where an ultrasonic flaw detection test is not expected, a normal ultrasonic flaw detection test may not be applicable even though the risk has become apparent over time. Examples of such a portion include a case where the shape of the position to be inspected is complicated due to integral forging or the like.

As a conventional technique for ultrasonic flaw detection test of such a part, ultrasonic waves are applied to the inner surface of the pipe for defects of the inner pipe seat joined by fillet welding of the pipe where there is no path for ultrasonic waves to reach from the surface. A method called one-skip, in which the light is reflected and then reached, has been proposed.

Japanese Unexamined Patent Publication No. 2010-25676

However, the proposed one-skip method described above is based on the premise that the shape of the reflecting surface to be skipped is a continuous plane. If this skip surface is not flat, ultrasonic waves are reflected or scattered in unexpected directions, so that the reliability of the flaw detection test cannot be maintained.

The embodiment of the present invention has been made in consideration of such circumstances, and when the ultrasonic wave is reflected to reach a defect, a highly reliable test result can be obtained even if the reflecting surface is not a continuous plane. The purpose is to provide ultrasonic flaw detection technology.

In the ultrasonic flaw detector according to the embodiment, an ultrasonic transmission / reception unit for transmitting and receiving ultrasonic waves to each of a plurality of ultrasonic elements arranged in an array probe, a first surface on the incident side of the ultrasonic waves, and a back side thereof. A database that holds shape information of an object to be inspected in which at least the second surface is formed in a discontinuous plane, and the ultrasonic waves transmitted from the ultrasonic element reflect the second surface. A propagation time calculation unit that calculates the propagation time until reaching the focal point in the vicinity of the first surface based on the shape information, and the propagation time of the ultrasonic element selected as a reference point from a plurality of pieces. The delay time calculation unit that calculates the difference between the propagation time of the ultrasonic element and the propagation time as the delay time, and the timing of at least one of the transmission and the reception of the ultrasonic wave are adjusted based on the delay time, respectively. A waveform synthesizing unit for synthesizing a plurality of echo waveforms received by the ultrasonic element of the above.

According to an embodiment of the present invention, there is provided an ultrasonic flaw detection technique that can obtain highly reliable test results even if the reflecting surface is not a continuous plane when reflecting ultrasonic waves to reach defects.

The block diagram of the ultrasonic flaw detector according to the embodiment of this invention. Explanatory drawing of ultrasonic wave transmitted from a group of elements. (A) (B) Explanatory drawing of setting example of ultrasonic element in element group. The explanatory view of the linear scanning system of the ultrasonic flaw detector which concerns on 1st Embodiment. The explanatory view of the linear scanning system of the ultrasonic flaw detector which concerns on 2nd Embodiment. The explanatory view of the sector scanning method of the ultrasonic flaw detection apparatus which concerns on 3rd Embodiment. (A) (B) (C) (D) Explanatory drawing of ultrasonic wave propagation path and composite waveform. (A) (B) (C) Explanatory drawing of the delay time calculation unit for calculating the delay time. Explanatory drawing which synthesizes an echo waveform using the transmission side delay time and the reception side delay time. The figure which shows the flaw detection image displayed in the drawing part. A graph showing the composite waveform displayed in the drawing section. (A) Front view of the jet pump, (B) Partial enlarged view. Enlarged cross-sectional view of the mating portion of the jet pump transition piece and the jet pump beam.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the ultrasonic flaw detector 10 according to the first embodiment includes an ultrasonic transmission / reception unit 11 for transmitting and receiving ultrasonic waves U to each of a plurality of ultrasonic elements 31 arranged on the array probe 30. A database 12 that holds shape information 45 of an object to be inspected 40 in which at least the second surface 42 of the first surface 41 on the incident side of the ultrasonic wave U and the second surface 42 on the back side thereof is formed in a discontinuous plane, and Propagation time calculation unit 16 that calculates the propagation time T until the ultrasonic wave U transmitted from the ultrasonic element 31 reflects the second surface 42 and reaches the focal point F near the first surface 41 based on the shape information 45. And the delay time calculation unit 17 that calculates the difference between the propagation time T of the ultrasonic element 31 selected as the reference point C from among the plurality of ultrasonic elements 31 and the propagation time T of the other ultrasonic elements 31 as the delay time Δt, and the delay. It includes a waveform synthesizing unit 18 that adjusts at least one timing of transmission and reception of ultrasonic waves U based on the time Δt and synthesizes a plurality of echo waveforms 35 received by each ultrasonic element 31.

The propagation time calculation unit 16 first calculates the propagation path of the ultrasonic wave U, reflecting the shape information 45 of the object 40 to be inspected having the first surface 41 and the second surface 42. As shown in FIG. 1, the ultrasonic wave U transmitted from a certain ultrasonic element 31 is incident at an incident angle α at an incident point I on the first surface 41a and propagates in the direction of a refraction angle β according to Snell's law. .. The intersection of the half straight line extending from the incident point I in the direction of the refraction angle β and the second surface 42 is the reflection point R. The ultrasonic wave U incident on the reflection point R has a component that is totally reflected due to the relationship between the angle of the tangent line of the reflection point R and the refraction angle β, and the totally reflected ultrasonic wave is the focal point F in the vicinity of the first surface 41b. Is reached at an arrival angle of γ. Although the reaching angle γ is represented by the angle formed by the normal line of the first surface 41b, it can be represented by using an arbitrary reference line such as the angle formed by the normal line of the first surface 41a.

Then, by dividing the distance of the propagation path of the obtained ultrasonic wave U by the sound velocity of the subject 40 to be inspected, the propagation time T until the ultrasonic wave U reaches the focal point F from the ultrasonic element 31 can be obtained. In this way, the propagation time T of the ultrasonic wave U from each of the ultrasonic elements 31 constituting the probe 30 to the focal point F can be obtained. The propagation path of the ultrasonic wave U transmitted from the ultrasonic element 31 and the propagation time T thereof can be obtained by setting the incident angle α, or can be obtained by setting the focal point F.

The delay time calculation unit 17 selects a part of the ultrasonic elements 31 arranged in the array probe 30 as the element group E, and further selects the ultrasonic element 31 to be the reference point C from the element group E. Then, the difference between the propagation time T of the ultrasonic element 31 at the reference point C and the propagation time T of the other ultrasonic element 31 is calculated as the delay time Δt. Then, the timing is adjusted by the delay time Δt, and the voltage signal is input from the transmission unit 11a to each ultrasonic element 31 constituting the element group E. Then, as shown in FIG. 2, the ultrasonic waves U transmitted from the respective ultrasonic elements 31 constituting the element group E enter the first surface 41, reflect the second surface 42, and all focus on the focal point F. It is converged.

FIG. 3 is an explanatory diagram of a setting example of the ultrasonic element 31 in the element group E. The element group E is defined by selecting one or more ultrasonic elements 31 located on both sides or one of the set reference points C, and including the ultrasonic element 31 at the reference point C. As shown in FIG. 3A, the element group E may be selected as a range of a certain mass, or may be selected as a sparse element group E as shown in FIG. 3B.

The maximum value of the element group E can be taken up to the total number of the ultrasonic elements 31 constituting the array probe 30. Further, in selecting the ultrasonic element 31 constituting the element group E to be scanned, it is also possible to select the ultrasonic element 31 located at convenient coordinates when the focal point F and the reaching angle γ are slightly changed. Further, the ultrasonic wave U propagating the object to be inspected 40 can be calculated as a wave in another mode beyond the reflection point R. For example, the incident point I to the reflection point R may be a longitudinal wave, and the reflection point R to the focal point F may be a mode-converted transverse wave.

(First Embodiment)
FIG. 4 is an explanatory diagram of a linear scanning method of the ultrasonic flaw detector 10 according to the first embodiment. The scanning unit 20 (FIG. 1) in the first embodiment selects a part of the ultrasonic elements 31 arranged in the array probe 30 as the element group E (E _{1 to} E ₅ ), and selects the selected element group E. By linear scanning, the focal points F (F _{1 to} F ₅ ) are scanned along the first surface 41b.

In the ultrasonic flaw detector 10 of the first embodiment, the ultrasonic _{wave U (U 1 to} U ₅ ) transmitted from the ultrasonic element 31 selected as _{the reference point C (C 1 to} C ₅ ) is targeted for inspection 40. The delay time Δt is calculated so that the incident angle α at the time of incident becomes constant. In the first embodiment, the _{ultrasonic element 31 serving as the reference point C (C 1 to} C ₄ ) and the incident angle α are set as initial conditions, and then the focal point F is determined based on the shape information 45.

(Second Embodiment)
FIG. 5 is an explanatory diagram of a linear scanning method of the ultrasonic flaw detector 10 according to the second embodiment. The scanning unit 20 (FIG. 1) in the second embodiment selects a part of the ultrasonic elements 31 arranged in the array probe 30 as the element group E (E _{1 to} E ₄ ), and selects the selected element group E. By scanning, the focal points F (F _{2 to} F ₄ ) are linearly scanned along the first surface 41b.

In the ultrasonic flaw detector 10 of the second embodiment, the arrival angle γ when the ultrasonic wave U transmitted from the ultrasonic element 31 selected as the reference point C and reflected on the second surface 42 reaches the focal point F is constant. The delay time Δt is calculated so as to be.

When linear scanning is performed along the first surface 41b, it is required that two or more propagation paths of the ultrasonic waves U are formed in parallel so that the arrival angle γ is constant. The term "parallel" as used herein is defined as having an error within ± 5 °, preferably within ± 2 °, with respect to the assumed arrival angle γ. In the second embodiment, after setting the focal point F and the reaching angle γ as initial conditions, the ultrasonic element 31 to be the _{reference point C (C 1 to} C _{4) is determined based on the shape information 45.}

(Third Embodiment)
FIG. 6 is an explanatory diagram of a sector scanning method of the ultrasonic flaw detector 10 according to the third embodiment. In the third embodiment, the propagation time T of the ultrasonic wave U transmitted from the ultrasonic element 31 selected as the reference point C is calculated so as to be scanned, and the focal point F (F _{2 to} F ₄ ) is the first surface. The sector is scanned along 41b.

The explanation will be continued by returning to FIG. The array probe 30 (hereinafter, simply referred to as “probe 30”) damps ultrasonic waves with an ultrasonic element 31 such as a piezoelectric element manufactured by Ceramics, which generates ultrasonic waves by a piezoelectric effect such as a composite material, a polymer film, or the like. It is composed of a damping material and a front plate attached to the ultrasonic oscillation surface. In each embodiment, the probe 30 is disclosed as a linear array probe in which piezoelectric elements are arranged one-dimensionally.

However, the probe 30 to be applied includes a 1.5-dimensional array probe in which the piezoelectric elements are divided into non-uniform sizes in the depth direction of the linear array probe, a matrix array probe in which the piezoelectric elements are two-dimensionally arranged, and a ring. Ring array probe in which the shape piezoelectric elements are arranged concentrically, split type ring array probe in which the piezoelectric element of the ring array probe is divided in the circumferential direction, non-uniform array probe in which the piezoelectric elements are unevenly arranged, circumference of an arc Examples thereof include an arcuate array probe in which an element is arranged at a directional position, a spherical array probe in which an element is arranged on a spherical surface, and the like.

Further, the ultrasonic array probe of other shapes can be used without being limited to these. Further, a plurality of these ultrasonic array probes can be combined regardless of the type and applied to tandem flaw detection. In addition, the above-mentioned ultrasonic array probes include those that can be used in air or in water by caulking or packing.

When installing the probe 30, a wedge (not shown) may be used to incident the ultrasonic wave U on the object to be inspected 40 at a highly directional angle. For this wedge, an isotropic material that can propagate ultrasonic waves and whose acoustic impedance is known is used. Specific examples include acrylic, polyimide, gel, and other polymers, and whether the acoustic impedance is close to or the same material as the front plate of the probe 30, or whether the acoustic impedance is close to the object to be inspected 40. Alternatively, the same material is used.

Further, the wedge may adopt a composite material in which the acoustic impedance is changed stepwise or gradually, and other materials can be applied without being limited to the above-mentioned materials. Further, a damping material may be arranged inside or outside the wedge so that the multiple reflection waves in the wedge do not affect the flaw detection result, a mountain-shaped wave-eliminating shape may be provided, or a multiple reflection reduction mechanism may be provided. In this embodiment, the description of the wedge is omitted when the ultrasonic wave is incident on the object 40 to be inspected from the probe 30.

The probe 30 and the wedge, the wedge and the object to be inspected 40, or the probe 30 and the object to be inspected 40 are acoustically coupled by an acoustic contact medium 47. The acoustic contact medium 47 is a medium capable of propagating ultrasonic waves, such as water, glycerin, machine oil, castor oil, acrylic, polystyrene, and gel, and other media can be applied without limitation. Further, in the description of the present embodiment, the description of the acoustic contact medium 47 may be omitted when the ultrasonic waves are incident on the object 40 to be inspected from the probe 30.

The ultrasonic transmission / reception unit 11 is composed of a transmission unit 11a and a reception unit 11b. The transmission unit 11a inputs a voltage signal having an arbitrary waveform to the connected ultrasonic element 31. Examples of the input voltage waveform include a sine wave, a sawtooth wave, a square wave, a spike pulse, and the like, and may be a bipolar having both positive and negative pole values, or a unipolar with either positive or negative swing. Further, an offset may be added to either positive or negative. Further, the voltage waveform can be increased or decreased in application time and repetitive wave number such as single pulse, burst or continuous wave.

The drawing unit 19 generates a flaw detection image 37 of the inspection target 40 based on the composite waveform M obtained by synthesizing a plurality of echo waveforms 35. The drawing unit 19 may be any one that can display digital data, and may be a PC monitor, a television, a projector, or the like, and may be one such as a cathode ray tube that is once converted into an analog signal and then displayed. Further, the drawing unit 19 may have a user interface function of generating an alarm by sound or light emission according to a set condition or inputting an operation as a touch panel.

The control unit (not shown) that controls the various functional units described above is a device having a function of performing general-purpose calculation and data communication as represented by a PC, and is a device other than the probe 30 in the above-described configuration. It has a configuration in which things are included or each functional part is interconnected with a communication cable.

The first surface 41 on one side of the object to be inspected 40 has a first surface 41a to which the probe 30 can be brought into contact and a first surface 41b to which the probe 30 cannot be brought into contact due to the presence of an obstacle 48. doing. The second surface 42 on the back side of the object to be inspected 40 is a second surface 42a on the back side of the probe contact surface (first surface 41a) and an extension surface of the probe back surface (second surface 42a). Connects the second surface 42b on the back side of the contact surface (first surface 41b) of the obstacle 48, the probe back surface (second surface 42a), and the obstacle back surface (second surface 42b). It has a connecting surface 42c and a connecting surface 42c.

When the defect 46 is present in the vicinity of the obstacle contact surface (first surface 41b), the object 40 to be inspected having such a structure can directly propagate the ultrasonic wave U to the defect 46. Can not. That is, for this defect 46, the ultrasonic wave U incident on the probe contact surface (first surface 41a) is reflected on the second surface 42 (any of 42a, 42b, 42c) on the back side. It can only be propagated indirectly.

The form of the first surface 41b includes not only the case where the obstacle 48 is arranged on the upper surface thereof but also the case where the probe 30 cannot be brought into contact with the probe 30 due to the structural circumstances of the probe 30 and its peripheral mechanism. The second surfaces 42a and 42b are surfaces that can be represented by a function of a degree of quadratic or lower, such as a plane or a curved surface, respectively. The connection surface (second surface 42c) connecting these second surfaces 42a and 42b is not limited to the one represented by a quadratic function, but its start and end form a boundary with the second surfaces 42a and 42b, respectively. doing.

The propagation path of the ultrasonic wave U and the composite waveform M will be described with reference to FIGS. 7 (A), (B), (C), and (D). In the following illustrations, the ultrasonic wave U does not reflect the back surface of the object to be inspected 40 and is simply described in the case where it directly reaches the focal point F. However, the ultrasonic wave U is the object to be inspected 40. The same explanation holds for the case of reflecting the back surface. When transmitting ultrasonic waves, ultrasonic waves U are transmitted from one ultrasonic element 31 in the probe 30, and when receiving ultrasonic waves U, one or more ultrasonic elements 31 receive ultrasonic waves U, respectively. As shown in FIGS. 7A, 7B, and 7C, such a sequence is performed once or more while changing the ultrasonic element i (i = 1, 2, 3, ..., N) that transmits ultrasonic waves. repeat.

As a result, the ultrasonic waveform U (i, j) (echo waveform 35) transmitted by the ultrasonic element i (i = 1 to N) and received by the ultrasonic element j (j = 1 to N) is obtained. .. More specifically, for transmission and reception of ultrasonic waves U, one ultrasonic element 31 transmits ultrasonic waves U, and a plurality of ultrasonic elements 31 receive ultrasonic waves U, and each ultrasonic element 31 is in an independent state. The ultrasonic waveform U (i, j) is retained. When the probe 30 composed of N ultrasonic elements 31 is used, the ultrasonic waveform of a maximum N × N pattern is recorded by changing the transmitting element.

Here, it is also possible to have a plurality of elements used for transmission while maintaining the function of holding the waveform in an independent state for each ultrasonic element 31 for reception. In this case, the delay time Δt can be adjusted to make the ultrasonic waves plane, focus, and diffuse. The ultrasonic wave U incident on the object to be inspected 40 is reflected and scattered by the surface of the object to be inspected 40 and the defects 46 represented by cracks and inclusions existing inside or on the surface of the object to be inspected, and the reflection thereof. The generated ultrasonic waves are received by the ultrasonic element of the probe 30.

The calculation of the delay time Δt in the delay time calculation unit 17 will be described based on FIGS. 8A, 8B, and 8C. Here, the ultrasonic element 31 constituting the element group E is represented by the center coordinates e (e1 to e7). The ultrasonic element 31 at the e1 position, which has the longest propagation time T, is set at the reference point C.

The delay time Δt is calculated from the positional relationship between the center coordinates e and the focal point F of each ultrasonic element 31. Here, the focal point F is the coordinates obtained from the center coordinates e (e1 to e7) of each ultrasonic element 31 of the element group E that generates the composite waveform M to a certain depth through the path of the incident angle and the refraction angle. is there. By dividing the linear distance from the center coordinates e (e1 to e7) of each ultrasonic element 31 to the focal point F by the speed of sound of the object to be inspected, until the ultrasonic waves emitted from each ultrasonic element 31 reach the focal point F. Propagation time T is obtained respectively.

As shown in FIGS. 8B and 8C, the propagation time T of all the ultrasonic elements 31 is subtracted by the longest propagation time T, and the positive and negative inverted ones are given to each ultrasonic element 31. The delay time is Δt. When the acoustic contact medium 47 is provided between the probe 30 and the object to be inspected 40, the point at which ultrasonic waves are incident on the object to be inspected 40 from each ultrasonic element 31 is calculated using Snell's law, and the acoustic contact medium 47 is provided. And the sound wave velocity of the subject 40 to be inspected are used to calculate the propagation time T required for each propagation, and then the delay time Δt is calculated.

The delay time Δt is calculated on both the transmission and reception paths. The surface shape of the inspection target used at this time is not limited to a general flat surface or an inclined flat surface, and even if there is a curvature or uneven portion, geometric calculation can be performed in consideration of the curvature or uneven portion. This is possible by reflecting the angle information (tangential angle) of the point on the surface on which the ultrasonic wave U is incident when calculating the incident point using Snell's law.

The waveform synthesizing unit 18 assigns the delay time Δt obtained by the delay time calculation unit 17 to the center coordinates e (e1 to e7) of each of the ultrasonic elements 31 constituting the element group E, and the respective ultrasonic elements 31 The signal of the obtained echo waveform 35 is shifted in the time axis direction by the delay time Δt, and the signals of the shifted elements at the same time are combined to obtain the composite waveform M.

FIG. 9 shows a case where the transmitting side delay time required to focus the transmitted ultrasonic waves and the receiving side delay time required to focus the received ultrasonic waves are added together to obtain the delay time. ing. Although the method of forming an arbitrary synthetic waveform M offline after obtaining the most basic ultrasonic waveform U (i, j) is shown here, ultrasonic excitation and ultrasonic waves reflecting the delay time are shown online. The same processing as that of a normal phased array or aperture synthesis method for ultrasonic synthesis may be performed.

FIG. 10 is a diagram showing a flaw detection image 37 displayed on the drawing unit 19 (FIG. 1). FIG. 11 is a graph showing the composite waveform M displayed on the drawing unit 19. The drawing unit 19 can draw the waveform intensity of the composite waveform M from the reference point C to a part or all of the line connecting the incident point I, the reflection point R, and the focal point F to obtain the flaw detection image 37. As shown in FIG. 11, the composite waveform M is roughly classified into a path from the central element C to the incident point I, a path from the incident point I to the reflection point R, and a path from the reflection point R to the focal point F.

As shown in FIG. 10, the flaw detection image 37 is obtained by dividing the range to be drawn by a grid and plotting the intensity of the composite waveform M corresponding to the propagation time to each grid. At this time, it is not necessary to draw the propagation paths of all the composite waveforms M, and the values may be limited to some values near the focal point F, for example. For example, an aperture synthesis image can be obtained by taking a plurality of focal points F and plotting only the intensity of the composite waveform M obtained at each focal point F.

FIG. 12A is a front view of the jet pump 50, and FIG. 12B is a partially enlarged view thereof. Further, FIG. 13 is an enlarged cross-sectional view of a fitting portion between the transition piece 51 of the jet pump 50 and the jet pump beam 52.

The jet pump 50 is installed in the reactor pressure vessel of a nuclear power plant. An example will be described in which the jet pump beam 52 of the jet pump 50 is set as the object to be inspected 40 (FIG. 1) and the defect 46 existing in the fitting portion is detected. For example, when the operation of the plant is stopped and the upper part of the reactor pressure vessel is open, such as in a periodic inspection, the probe 30 can be incident on the first surface 41a of the jet pump beam 52 by using the access device. Install in position. The second surface 42 that forms the focal point F of the reflected wave of the ultrasonic wave U in the vicinity (for example, within 10 mm) is the surface on which the transition piece 51 and the jet pump beam 52 are fitted.

In this embodiment, it is assumed that the inside of the reactor pressure vessel is filled with water, and the acoustic contact medium is water or pure water. Therefore, by arranging the probe 30 at a position away from the first surface 41a of the jet pump beam 52, it is possible to detect the fitting surface of the transition piece 51 and the jet pump beam 52. The flaw detection test is not limited to the fitting surface between the transition piece 51 and the jet pump beam 52 illustrated, and the flaw detection test can be performed with other internal structures in the furnace as the object to be inspected 40. Internal structure maintenance becomes possible.

The embodiment of the present invention can be applied to an ultrasonic flaw detection method generally called a phased array ultrasonic flaw detection test. Among them, the linear scan method in which the ultrasonic wave element to be driven is electronically scanned while forming the ultrasonic wave U in a certain direction, and the angle at which the ultrasonic wave U is formed while fixing or electronically manipulating the ultrasonic wave element to be driven are fan-shaped. Suitable for those that can be visualized using ultrasonic waves, such as the sector scan method that changes to, the Total Focusing Method (TFM) that comprehensively focuses on an arbitrary coordinate area and focuses the beam, and the so-called aperture synthesis method. Applies to.

According to the ultrasonic flaw detector of at least one embodiment described above, by retaining the shape information of the object to be inspected, when the ultrasonic waves are reflected to reach the defect, even if the reflecting surface is not a continuous plane, It is possible to obtain highly reliable test results.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

10 ... Ultrasonic flaw detector, 11 ... Ultrasonic transmission / reception unit, 11b ... Receiver unit, 11a ... Transmission unit, 16 ... Propagation time calculation unit, 17 ... Delay time calculation unit, 18 ... Waveform synthesis unit, 19 ... Drawing unit, 20 ... scanning unit, 30 ... array probe (probe), 31 ... ultrasonic element, 35 ... echo waveform, 37 ... flaw detection image, 40 ... subject to be inspected, 41 (41a, 41b) ... first surface, 42 (42a, 42b) ) ... Second surface, 42c ... Connection surface, 45 ... Shape information, 46 ... Defects, 47 ... Acoustic contact medium, 48 ... Obstacles, 50 ... Jet pump, 51 ... Transition piece, 52 ... Jet pump beam, T ... Propagation Time, Δt ... Delay time, F ... Focus, α ... Incident angle, β ... Refraction angle, γ ... Reach angle, U ... Ultrasonic wave.

Claims (7)

An ultrasonic transmitter / receiver that transmits and receives ultrasonic waves to each of a plurality of ultrasonic elements arranged in an array probe.
A database that holds shape information of the object to be inspected, in which at least the second surface of the first surface on the incident side of the ultrasonic wave and the second surface on the back side thereof is formed by a discontinuous plane.
A propagation time calculation unit that calculates the propagation time until the ultrasonic wave transmitted from the ultrasonic element reflects the second surface and reaches the focal point in the vicinity of the first surface based on the shape information.
A delay time calculation unit that calculates the difference between the propagation time of the ultrasonic element selected as a reference point from a plurality of reference points and the propagation time of the other ultrasonic element as a delay time.
An ultrasonic wave including a waveform synthesizer that adjusts at least one timing of the transmission and reception of the ultrasonic wave based on the delay time and synthesizes a plurality of echo waveforms received by each of the ultrasonic elements. Flaw detector. In the ultrasonic flaw detector according to claim 1,
A supersonic unit including a scanning unit that linearly scans the focus along the first surface by selecting a part of the ultrasonic elements arranged in the array probe as an element group and scanning the selected element group. Ultrasonic flaw detector. In the ultrasonic flaw detector according to claim 2,
Ultrasonic flaw detection in which the delay time is calculated so that the arrival angle when the ultrasonic wave transmitted from the ultrasonic wave element selected as the reference point and reflected from the second surface reaches the focal point is constant. apparatus. In the ultrasonic flaw detector according to claim 1,
An ultrasonic flaw detection unit including a scanning unit that calculates to scan the propagation time of the ultrasonic wave transmitted from the ultrasonic wave element selected as the reference point and causes the focal point to scan a sector along the first surface. apparatus. The ultrasonic flaw detector according to any one of claims 1 to 4.
An ultrasonic flaw detection device including a drawing unit that generates a flaw detection image of an object to be inspected based on a composite waveform obtained by synthesizing a plurality of the echo waveforms. A step of transmitting and receiving ultrasonic waves to each of a plurality of ultrasonic elements arranged in an array probe, and
A step of holding in a database the shape information of an object to be inspected in which at least the second surface of the first surface on the incident side of the ultrasonic wave and the second surface on the back side thereof is formed by a discontinuous plane.
A step of calculating the propagation time until the ultrasonic wave transmitted from the ultrasonic element reflects the second surface and reaches the focal point in the vicinity of the first surface based on the shape information.
A step of calculating the difference between the propagation time of the ultrasonic element selected as a reference point from a plurality of reference points and the propagation time of the other ultrasonic element as a delay time, and
An ultrasonic flaw detection method including a step of adjusting at least one timing of the transmission and reception of the ultrasonic wave based on the delay time and synthesizing a plurality of echo waveforms received by each of the ultrasonic elements. .. A method for maintaining a structure in a furnace, which uses the ultrasonic flaw detector according to any one of claims 1 to 5 to detect defects existing in the vicinity of the contact surface of a jet pump beam fitted to a transition piece.

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