JP2009192236A - Ultrasonic flaw detection method and ultrasonic flaw detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method and an ultrasonic flaw detector for accurately detecting flaw in an inspected part, including a joint part of a complex shape which extends along the joint part, as to two members mutually connected via the joint part. <P>SOLUTION: On a flaw detection surface 53, a transmitting probe 12a and a receiving probe 12b are juxtaposed/disposed, in a direction orthogonal or substantially orthogonal to the inspected part 55 extending along the joint part We. This method is such that ultrasonic waves are transmitted from the transmitting probe 12a toward the inspected part 55, while both the probes 12 are moved along the inspected part 55 on the detection surface 53, and that the ultrasonic waves which are diffracted or reflected by a flaw CL are received by the receiving probe 12b, when there is the flaw CL generated in the inspected part 55. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus that detect defects such as surface cracks, internal cracks, poor fusion, and poor penetration of an object to be inspected using ultrasonic waves. In particular, an ultrasonic flaw detection method and an ultrasonic method that are advantageous for detecting and quantifying defects in a junction having a complicated shape such as a junction between a thick pressure vessel and a nozzle or a manhole attached to the thick pressure vessel. The present invention relates to a sound flaw detection apparatus.

  Conventionally, a defect in an inspected part including a joint part of a first member and a second member joined to each other, for example, a welded part in two steel materials (first steel material and second steel material) joined by welding, and Various methods are known as ultrasonic flaw detection methods for detecting defects (surface cracks, internal cracks, poor fusion, poor penetration, etc.) in the periphery.

  For example, a TOFD (Time Of Flight Diffraction) method described in Patent Document 1 is known as an ultrasonic flaw detection method for a welded portion (inspected portion) of a straight simple shape in butt welding of a flat plate or the like. . In this TOFD method, as shown in FIGS. 11A to 11C, a pair of probes 103a is provided on the flaw detection surface (front surface) 102 of two flat steel materials 101a and 101b which are butt welded. 103b are arranged symmetrically across the welded portion WL. One of the pair of probes 103a and 103b is a transmission probe 103a that transmits ultrasonic waves to the flaw detection surface 102 and the inside of the steel material 101 (101a and 101b) by transmitting ultrasonic waves to the flaw detection surface 102. The other is a receiving probe 103b that receives the ultrasonic waves propagated from the flaw detection surface 102 of the steel material 101.

  In such a state, the transmitting probe 103a transmits ultrasonic waves toward the welded portion (inspected portion) WL, and the receiving probe 103b receives the ultrasonic waves while the two probes 103a are receiving the ultrasonic waves. , 103b moves (scans) on the surface (flaw detection surface) 102 of the steel material 101 along the welded portion WL with the interval kept constant (in the direction of arrow V in FIG. 11C).

  During the scanning, the receiving probe 103b is transmitted from the transmitting probe 103a and propagates along the flaw detection surface 102, and from the upper end CL1a of the defect CL1 generated in the welded portion WL. The diffracted wave (or scattered wave) 111, the diffracted wave (or scattered wave) 112 from the lower end CL1b of the defect CL1, and the bottom surface reflected wave 113 reflected by the bottom surface 104 of the steel material 101 are received (FIGS. 11A and 11). (See (b)). Thus, the propagation time differences TM1 to TM4 are obtained from the received waveform of the ultrasonic waves received by the receiving probe 103b (see FIG. 11B), and the propagation time differences TM1 to TM4 and the ultrasonic waves propagating in the steel material 101 are obtained. From the propagation speed, the thickness T of the steel material 101, the distance D between the probes 103a and 103b, and the like, the positions of the upper end CL1a and the lower end CL1b of the defect CL1 are obtained geometrically. The height h of the defect CL1 and the depth (defect depth) d of the defect CL1 from the flaw detection surface 102 are derived from the positions of the upper end CL1a and the lower end CL1b of the defect CL1 thus obtained.

  Such a TOFD method is a flaw detection method used for ultrasonic flaw detection with respect to a welded portion WL having a simple shape as described above. Therefore, both sides of the welded portion (inspected portion) are composed of curved surfaces or the like. For example, a nozzle weld WC that is a joint between a cylindrical nozzle 201b and a cylindrical shell 201a as shown in FIGS. 12 (a) and 12 (b). could not.

  Therefore, a CG-TOFD (Complex Geometry Time Of Flight Diffraction) method has been developed, which is an extension of the TOFD method in order to enable flaw detection of a welded portion (inspected portion) having a complicated shape such as the nozzle welded portion WC. . In this method, one probe (reception probe) 203b is arranged on the surface of the nozzle 201b, the other probe (transmission probe) 203a is arranged on the surface of the shell 201a, and the inside of the nozzle welded portion WC is set. The position of the defect CL2 (the positions of the upper end CL2a and the lower end CL2b) is analyzed by analyzing the received waveforms of the ultrasonic waves 210 to 213 that are diffracted by the upper end CL2a and the lower end CL2b of the defect CL2 and propagate to the reception probe 203b through different paths. Position) and size.

  However, in this CG-TOFD method, when the inner surface 204 side of the nozzle welded portion WC is overlaid, many reflected waves (interference signals) irregularly reflected by the overlaid welded portion 205 appear. When the interference signal is received by the reception probe 203b, there has been a problem that the S / N ratio is lowered.

Therefore, as shown in FIGS. 13A to 13C, both the transmission probe 303a and the reception probe 303b are welded to the surface (flaw detection surface) 301 of the base portion (shell) 201a. A flaw detection method has been developed that is arranged along the part (inspected part) WC. In this method, the transmission probe 303a transmits ultrasonic waves toward the nozzle welded portion WC in the state of being arranged as described above. If a defect CL3 has occurred in the nozzle weld WC, the reception probe 303b receives an ultrasonic signal from the defect CL3, and analyzes the received ultrasonic wave from the defect CL3 to perform nozzle welding. The defect CL3 in the part WC is detected (see Patent Document 2). That is, the ultrasonic signal from the defect CL3 reaches the reception probe 303b directly without being reflected by the inner surface of the nozzle 201b, and the interference signal is analyzed by analyzing the reception waveform of the directly reached ultrasonic wave. Even if many appear, the defect CL3 can be accurately detected (analysis of the received waveform, etc.). In this ultrasonic flaw detection method, detection of a defect (crack) generated at the nozzle inner corner is mainly performed, but a case where it is applied to flaw detection of a welded portion is assumed.
JP 2002-62281 A JP 2004-258008 A

  However, in the ultrasonic flaw detection method performed in a state where the pair of probes 303a and 303b are arranged along the part to be inspected (nozzle welded part) WC on the common surface 301 as described above, the transmission probe is used. An ultrasonic wave is transmitted from 303a, and the ultrasonic wave signal from the defect CL3 is received by the receiving probe 303b (see FIG. 13C), so that the inspection object corresponding to the center position C between the two probes 303a and 303b. Defects can only be detected accurately within the portion WC. That is, when the flaw detection range (inspection range) in the inspected part WC is narrow and the defect CL3 extends in the direction along the inspected part WC, the length of the defect in the direction along the inspected part CW (hereinafter simply “ Also referred to as “defect length”.) There is a concern that L1 cannot be detected accurately.

  Therefore, in view of the above problems, the present invention accurately detects a defect in a part to be inspected including a joint part having a complicated shape and extending along the joint part in two members connected to each other through the joint part. It is an object of the present invention to provide an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus that can be performed.

  In order to solve the above problem, both the transmitting and receiving probes 303a and 303b are arranged on the flaw detection surface 301 along the inspection target WC as described above, and the flaw detection surface 301 is aligned along the inspection target WC. A flaw detection method in which scanning is performed while moving up is conceivable.

  However, even when both probes are arranged and moved while being scanned in this way, the inspected portions of both probes on the flaw detection surface due to the shape of the member to be inspected (inspection target member) If the movement along the line is restricted (the distance that can be moved is limited), it is not possible to perform the flaw detection on the entire part to be inspected.

  Specifically, for example, a wall member 405 orthogonal to the part to be inspected 402 and the flaw detection surface 401 is provided as in the inspection target member 400 shown in FIGS. 14A and 14B. In this case, the wall member 405 restricts the movement (scanning) of the probes 403a and 403b along the part to be inspected 402 while maintaining a mutual distance (relative position).

  In this case, when the two probes 403a and 403b are respectively positioned at both end positions movable in the scanning direction, the parts e1 and e2 of the inspected part corresponding to the intermediate positions of the two probes 403a and 403b, respectively. The distance L3 of the entire portion to be inspected 402 along the extending direction is longer than the distance L2 in the direction along which the portion to be inspected 402 extends (hereinafter also simply referred to as “flaw detection range length”) L2. . For this reason, it is not possible to perform flaw detection on the entire inspection target portion 402.

  Note that the ultrasonic wave transmitting portion of the transmitting probe 403a and the ultrasonic wave receiving portion of the receiving probe 403b need to move (scan) while in contact with the flaw detection surface 401. Even when the flaw detection surface 401 is interrupted at the position where the wall member 405 is provided without the wall member 405 being provided, the movement of the two probes 403a and 403b along the part to be inspected 402 is performed. The inspection is restricted and the entire inspection target 402 cannot be flawed.

  Further, as shown in FIG. 15, for example, when ultrasonic testing is performed by the above method in the inspection target member 500 in which a cylindrical nozzle 501b is joined to a cylindrical circumferential shell 501a, transmission and reception are performed. Since the two probes 503a and 503b are arranged at intervals along the moving direction (inspected part 502), the transmission probe for the part of the inspected part corresponding to the center between the two probes is used. The arrival position of the ultrasonic wave is not constant and changes under the influence of the curvature change of the surface of the shell 501a (flaw detection surface) along the scanning direction of both probes. In particular, when the change in curvature in the scanning direction of the surface 504 of the shell 501a is large, it may be difficult to analyze the received ultrasonic waves.

  Therefore, as a result of intensive studies by the present inventors, the above problems have been solved by creating an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus having the following configuration.

  In the ultrasonic flaw detection method according to the present invention, an ultrasonic wave is propagated in a portion to be inspected including a joint portion of the first member and the second member that are joined to each other, and the propagated ultrasonic wave is received to receive the ultrasonic wave. An ultrasonic flaw detection method for detecting a defect in an inspection unit, wherein a first specific surface in the first member and a second specific in a second member are connected via the joint so as to intersect each other. On the flaw detection surface formed by the surface, a transmission probe that transmits the ultrasonic waves to the flaw detection surface and a reception probe that receives the transmitted ultrasonic waves from the flaw detection surface are formed in the joint portion. The probes are arranged in a state orthogonal to or substantially perpendicular to the inspected part extending along the two, and maintaining the distance from the portion where the first and second specific surfaces intersect each other. The flaw detection along the part to be inspected When an ultrasonic wave is transmitted from the transmitting probe toward the inspected part while moving upward, and a defect has occurred in the inspected part, an ultrasonic wave diffracted or reflected by the defect is received in the receiving probe. It is characterized by receiving at the child.

  In addition, the ultrasonic flaw detection apparatus according to the present invention propagates ultrasonic waves into a part to be inspected including the joints of the first member and the second member joined together, and receives the propagated ultrasonic waves. An ultrasonic flaw detection apparatus for detecting a defect in the inspected part, wherein the first specific surface in the first member and the second in the second member are connected via the joint so as to intersect each other. On the flaw detection surface formed by a specific surface, a transmission probe for transmitting the ultrasonic waves to the flaw detection surface arranged side by side in a direction orthogonal or substantially orthogonal to the part to be inspected extending along the joint. Both probes while maintaining the distance from the probe, the receiving probe that receives the transmitted ultrasonic waves from the flaw detection surface, and the portion where the first and second specific surfaces intersect each other The child follows the inspected part. The transmitting probe transmits the ultrasonic wave toward the inspected part while moving on the flaw detection surface, and the defect diffracted or reflected by the defect when the defect has occurred in the inspected part. And a defect detection means for receiving a sound wave by the reception probe and detecting a defect in the inspected part from the received signal.

  According to these configurations, the probes of the transmission probe and the reception probe are arranged in a direction orthogonal or substantially orthogonal to the inspected portion extending along the joint portion, and the inspected portion And moves (scans) along the flaw detection surface. Therefore, in the extending direction of the inspected part, the flaw detection range lengths of the two probes are equal to or substantially equal to the entire inspected part, and the entire inspected part or substantially the entire flaw can be detected. Become.

  Further, as described above, since both probes move along the inspected part and detect defects in the inspected part, not only the presence or absence of defects in the inspected part is detected, but also the inspected object. The length of the defect along the portion (hereinafter, also simply referred to as “defect length”) can be detected.

  Furthermore, even if the flaw detection surface is a curved surface that curves along the movement (scanning) direction of both probes (the curvature changes), the portion of the part to be inspected that the ultrasonic wave reaches from the transmission probe The change in the arrival position of the ultrasonic wave with respect to is smaller than that in the conventional scanning with a pair of probes arranged at intervals along the scanning direction. Therefore, the defect detection from the received waveform received by the receiving probe is easier than in the case where the conventional inspection target part is spaced.

  In the ultrasonic flaw detection method according to the present invention, both the transmission probe and the reception probe may be arranged on the first specific surface or the second specific surface, and the transmission One of the probe and the reception probe may be disposed on the first specific surface and the other may be disposed on the second specific surface.

  In any of these arrangements, since both the probes (transmitting probe and receiving probe) are arranged in a direction orthogonal or substantially orthogonal to the inspected part, the inspected part extends as described above. In the direction, the length of the flaw detection range of both the probes is equal to or substantially equal to the length of the entire inspected portion, and the entire inspected portion or substantially the entire flaw can be detected. In addition, even if the flaw detection surface is a curved surface that is curved along the scanning direction, the change in the arrival position of the ultrasonic wave with respect to the site of the part to be inspected where the ultrasonic wave arrives from the transmission probe is similar to the conventional one. This is smaller than when scanning with a pair of probes arranged at intervals along the scanning direction, and defect detection is facilitated.

  Also, the ultrasonic flaw detection method according to the present invention propagates an ultrasonic wave into a portion to be inspected including a bonded portion of the first member and the second member bonded to each other, and receives the propagated ultrasonic wave. An ultrasonic flaw detection method for detecting defects in the inspected part, wherein the first specific surface in the first member and the second in the second member are connected via the joint so as to cross each other. On the flaw detection surface formed by a specific surface, the transmission probe that transmits the ultrasonic waves to the flaw detection surface and the reception probe that receives the transmitted ultrasonic waves from the flaw detection surface are joined to each other. The first arrangement is arranged in a direction orthogonal or substantially orthogonal to the part to be inspected extending along the part, and both the distances from the part where the first and second specific surfaces intersect each other are maintained. Place the probe on the inspected part The ultrasonic wave transmitted from the transmitting probe toward the inspected portion while moving on the flaw detection surface, and when a defect has occurred in the inspected portion, the ultrasonic wave diffracted or reflected by the defect Is received by the receiving probe to scan the portion to be inspected, and the relative position of both probes in the first arrangement is changed along the direction orthogonal or substantially orthogonal to the second position. An arrangement is provided, and the inspected portion is scanned in the second arrangement.

  According to such a configuration, in both the first arrangement and the second arrangement, since both the probes are arranged in a direction orthogonal or substantially orthogonal to the inspected part, as in the above, In the direction in which the portions extend, the flaw detection range lengths of the two probes and the length of the entire portion to be inspected are equal or substantially equal, and the entire portion to be inspected or substantially the entire flaw can be detected. In addition, even if the flaw detection surface is a curved surface that is curved along the scanning direction, the amount of change in the arrival position of the ultrasonic wave with respect to the site of the part to be inspected that the ultrasonic wave reaches from the transmission probe is small as described above. Therefore, the received waveform received by the receiving probe can be easily analyzed.

  Further, in the scan in the first arrangement and the scan in the second arrangement, in the same manner as described above, in order to detect the defect lengths for the common defects occurring in the inspected portion, the scan in one arrangement is used. However, it is possible to accurately detect the defect length.

  In the case of a configuration in which scanning is performed in the first arrangement and the second arrangement, the ultrasonic waves respectively received by the reception probe in the scanning in the first arrangement and the second arrangement are further provided. Based on each of the first position and the second position, the potential positions where the ultrasonic diffraction and reflected portions of the defect in the inspected part may exist are derived, respectively. It is preferable that the position where the ultrasonic wave is diffracted or reflected in the defect in the inspected part is derived based on the existence possibility position.

  According to such a configuration, it is possible to derive an accurate position of the predetermined portion of the defect in the inspected portion. As a result, it is possible to accurately detect the length of the defect (hereinafter also simply referred to as “defect height”) in the direction orthogonal to the extending direction of the inspected part based on the exact position of the defect. Become.

  Specifically, for example, the defect height is detected (derived) as follows. First, when a defect has occurred in the inspected part, when scanning is performed in the first arrangement, a predetermined defect is detected from the transmission probe based on the ultrasonic wave received by the reception probe. A first defect signal propagation distance, which is a propagation distance of an ultrasonic wave that reaches the reception probe through a part (the upper end or the lower end of the defect), is obtained. Then, the propagation distance of the ultrasonic wave reflected from a virtual point in the first member or the second member from the transmission probe to the reception probe is matched with the first defect signal propagation distance. Obtaining a spheroid formed by the locus of the virtual point when the transmitting probe transmits ultrasonic waves in various directions to the flaw detection surface, passing through the spheroid and both probes A first possibility position (first position) where there is a possibility that a predetermined part (the upper end or the lower end of the defect) of the defect in the inspected portion, which is an intersecting line with a surface orthogonal to the flaw detection surface. (Locus).

  Next, when scanning is performed in the second arrangement, the second existence possibility position (second locus) is obtained in the same manner as described above.

  Of the first locus and the second locus thus obtained, the same portion of the defect derived from the ultrasonic wave received by the receiving probe through the same portion (upper end or lower end) of the defect ( By using the first locus and the second locus at the upper end or the lower end and obtaining the intersection point, the exact position of the predetermined portion (the upper end or the lower end) of the defect in the inspected part is derived. . The defect height is derived from the positions of the upper end and the lower end of the defect thus derived in the inspected part.

  That is, the first locus and the second locus at the upper and lower ends of the defect are respectively obtained by the scanning by the first arrangement and the scanning by the second arrangement, and the defect within the inspected part is obtained from the intersection. The upper end position and the lower end position are obtained, and the upper end position and the lower end position of the defect in the inspected part are accurately detected. By using these highly accurate upper and lower end positions, it is possible to accurately derive the defect height.

  Further, in the case where the arrangement of both probes is changed between the first arrangement and the second arrangement, in the first arrangement, both the transmission probe and the reception probe are the first. Arranged on a specific surface or a second specific surface, and in the second arrangement, one of the transmitting probe and the receiving probe is arranged on the first specific surface and the other is A configuration arranged on the second specific surface is preferable. In the first arrangement, one of the transmission probe and the reception probe is arranged on a first specific surface and the other is arranged on a second specific surface, In the arrangement of 2, the configuration in which both the transmission probe and the reception probe are arranged on the first specific surface or the second specific surface is also preferable.

  In any of these configurations, when the intersection between the first and second loci at the upper end (or lower end) of the defect is obtained, the intersection angle between the first and second loci increases, so that the locus is more accurately detected. The position of the intersection of each other can be specified. Therefore, it is possible to detect the position of the upper end (or lower end) of the defect in the inspection target portion with higher accuracy, and to detect the height of the defect with higher accuracy.

  In the first arrangement, one of the transmission probe and the reception probe is arranged on a first specific surface and the other is arranged on a second specific surface, In the arrangement of 2, the transmitting probe or the receiving probe is arranged at a position moved from the position arranged in the first arrangement on the same plane along the orthogonal or substantially orthogonal direction. It may be.

  Even in such a configuration, similarly to the above, the first locus and the second locus at the upper end and the lower end of the defect are respectively obtained by the scanning by the first arrangement and the scanning by the second arrangement, and the defect of the defect is determined from the intersection point. The upper end position and the lower end position in the inspected part are obtained, and the upper end position and the lower end position of the defect in the inspected part are accurately detected.

  As described above, according to the present invention, in two members connected to each other through a joint, it is possible to accurately detect a defect in a part to be inspected that includes a joint having a complicated shape and extends along the joint. An ultrasonic flaw detection method and an ultrasonic flaw detection apparatus that can be provided can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  The ultrasonic flaw detection apparatus according to the present embodiment uses ultrasonic waves to detect defects (surface cracks, internal cracks, poor fusion, melting) in the inspected part including the joint part of two members (inspection target members) joined to each other. This is a device for detecting an indentation defect, etc.). In the present embodiment, the inspection target member is a cylindrical nozzle welded (joined) to a shell formed in the shape of a cylindrical peripheral surface, and the inspected portion includes a welded portion between the shell and the nozzle and the weld. It is a site | part which extends along a welding part including the periphery of a part (refer Fig.3 (a)).

  Specifically, as shown in FIG. 1, an ultrasonic flaw detector 10 according to this embodiment includes a pair of probes 12a and 12b that transmit and receive ultrasonic waves, and the pair of probes 12a. , 12b are connected to each other via a cable k, and an analysis computer 40 for analyzing the presence / absence of a defect based on inspection information obtained by the ultrasonic flaw detector 30 is provided. .

  The pair of probes 12a and 12b is composed of a transmission probe 12a and a reception probe 12b as shown in FIGS. 2 (a) and 2 (b). The transmission probe 12a is for transmitting ultrasonic waves, specifically, longitudinal waves of pulsed ultrasonic waves, to a flaw detection surface 53 described later from a transmission portion 14a provided at the tip. Further, the receiving probe 12b is transmitted from the flaw detection surface 53 by the receiving portion 14b provided at the tip, in detail, from the transmission probe 12a, and the surface of the inspection target member 50 (flaw detection surface 53) and the inside. It is for receiving the ultrasonic wave which has propagated.

  The transmitting probe 12a and the receiving probe 12b (hereinafter sometimes simply referred to as “both probes 12”) restrict the arrangement position on the flaw detection surface 53 depending on the shape of the flaw detection surface 53. In some cases, the ultrasonic waves can be transmitted or received within a range of 0 to 90 ° (from the normal direction to the parallel direction of the flaw detection surface) with respect to the flaw detection surface 53.

  Further, a shoe 20 is attached to the tips of both probes 12 so that the probe 12a or 12b can smoothly move on the flaw detection surface 53. The shoe 20 has an abutting surface 22 at the tip portion so as to come into surface contact with the flaw detection surface 53. The shoe 20 is detachable from the probe 12a (or 12b), and is exchanged in accordance with the shape of the flaw detection surface 53. In the present embodiment, a concave portion 26 into which the probe tip is inserted is formed on a surface 24 opposite to the contact surface 22 in contact with the flaw detection surface 53 (upper side in FIG. 2A). A female screw is threaded on the inner peripheral surface 26a of 26. This female screw is engaged with a male screw threaded on the outer peripheral surface 16 of the tips of the probes 12a and 12b.

  In the present embodiment, the transmission probe 12a and the reception probe 12b are independent of each other. However, the relative positions of the transmission probe 12a and the reception probe 12b are fixed and a high-accuracy flaw detection is performed. In order to perform the above, they may be coupled to each other by a coupling mechanism (not shown).

  The ultrasonic flaw detector 30 includes a display means (monitor) 32 composed of a CRT, an LCD, etc., and generates and transmits a signal for generating an ultrasonic wave to the transmission probe 12a and a reception probe. The ultrasonic reception signal (reception waveform) from 12b is received, and the flaw detection result is displayed on the display means 32 (see, for example, FIGS. 4A and 4B). The ultrasonic flaw detector 30 also includes flaw detection result storage means (not shown) for storing the received waveform.

  The analysis computer 40 includes display means 42 composed of a CRT, LCD or the like. The flaw detection result information is read from the flaw detection result storage means of the ultrasonic flaw detector 30 and the defect presence position described later is analyzed. The analysis computer 40 is provided with a CPU, RAM, ROM, HDD, FDD, CDR, keyboard, mouse, etc. (not shown) as in a general-purpose computer (so-called personal computer), and is provided on a hard disk (or ROM, RAM, etc.). , An analysis program for analyzing the OS and the position of the defect is stored in advance.

  Instead of the hard disk, the analysis program may be stored in other external storage means such as a CD, LD, or memory card, and read into the RAM when executing the analysis.

  The ultrasonic flaw detection apparatus 10 according to the present embodiment has the above-described configuration. Next, a scanning method using both the probes 12 will be described with reference to FIGS. 3 (a) to 6 (b).

  The inspection target member 50 in the present embodiment includes a first member 51 and a second member 52 that are joined to each other. Specifically, a cylindrical nozzle (second member) 52 is welded (joined) to a cylindrical circumferential shell (first member) 51. A portion 55 to be inspected by the ultrasonic flaw detector 10 in the inspection target member 50 includes a welded portion We of the shell 51 and the nozzle 52 and the periphery of the welded portion We, and extends along the welded portion We. It is.

  First, a pair of probes 12 a and 12 b are arranged on the flaw detection surface 53 of the inspection target member 50. Here, the flaw detection surface 53 on which the probe 12a (or 12b) is arranged is the surface of the shell 51 (first specific surface of the first member 51) connected via the welded portion We so as to cross each other. ) And the surface of the nozzle 52 (second specific surface of the second member 52). In the present embodiment, a portion corresponding to the surface of the shell 51 in the flaw detection surface 53 may be referred to as a shell flaw detection surface 51a, and a portion corresponding to the surface of the nozzle 52 may be referred to as a nozzle flaw detection surface 52a.

  At this time, as shown in FIGS. 3A to 3C, the two probes (the transmitting probe and the receiving probe) 12a and 12b are covered along the welded portion We. They are arranged side by side in a direction orthogonal to the inspection unit 55. Both probes 12 are arranged on the shell flaw detection surface 51a. In the present embodiment, the two probes 12 are moved back and forth with respect to the inspected portion 55 on the surface of one member of the shell (first member) 51 and the nozzle (second member) 52 thus joined together. The arrangement arranged in a row is referred to as a first arrangement. In the present embodiment, the direction in which the two probes 12 are arranged is a direction orthogonal to the inspected portion 55, but is substantially orthogonal (preferably within 10 ° with respect to the orthogonal direction). It may be. In the first arrangement, the transmitting probe 12a is arranged on the front side with respect to the inspected part 55, and the receiving probe 12b is arranged on the rear side. The reception probe 12b may be disposed on the front side with respect to the unit 55, and the transmission probe 12a may be disposed on the rear side.

  After being arranged in this way, the two probes 12 follow the portion 55 to be inspected while maintaining the distance between the surface of the shell 51 and the surface of the nozzle 52, that is, the distance from the welded portion We. To move on the flaw detection surface 53 (shell flaw detection surface 51a). At this time, the transmission probe 12a moves while transmitting ultrasonic waves toward the inspected portion 55. On the other hand, the reception probe 12b is transmitted by the transmission probe 12a and propagates in the inspection target member 50, and when the defect CL is generated in the inspected portion 55, the reception probe 12b is diffracted or reflected by the defect CL. It moves while receiving the sound wave from the flaw detection surface 53.

  Thus, the two probes 12 arranged in the direction orthogonal to the inspected portion 55 accurately detect flaws in the inspected portion 55 near the intersection with the direction connecting the probes 12a and 12b. be able to. Therefore, the two probes 12 are arranged as described above, and the inspected portion 55 is scanned, so that the defects in the inspected portions 55 of the two probes 12 in the extending direction of the inspected portions 55 are accurately detected. The possible range (the flaw detection range length) and the entire length of the inspected portion 55 are equal or substantially equal, and the entire inspected portion 55 or substantially the entire flaw can be detected.

  Further, as described above, since the two probes 12 move along the inspected portion 55 and detect the defect CL in the inspected portion 55, only the presence / absence of the defect CL in the inspected portion 55 is detected. In addition, the length (defect length) L of the defect along the inspected portion 55 can also be detected (see FIG. 4B).

  Furthermore, even if the flaw detection surface 53 is a curved surface curved along the movement (scanning) direction of the two probes 12 as in the present embodiment, the ultrasonic wave from the transmission probe 12a reaches. The change of the arrival position of the ultrasonic wave with respect to the site of the inspection unit 55 is smaller than that in the conventional scanning with a pair of probes arranged at intervals along the scanning direction. In other words, the arrival position of the ultrasonic wave from the transmission probe 12a with respect to the portion of the inspected portion 55 is hardly affected by the curvature change of the flaw detection surface 53 along the scanning direction. Therefore, the defect detection from the received waveform received by the receiving probe is easier than in the case where the conventional inspection target part is spaced.

  The reception waveform (see FIG. 4A) obtained when the two probes 12 are scanned in the first arrangement in this way is transmitted to the ultrasonic flaw detector 30. The ultrasonic flaw detector 30 stores this received waveform in the flaw detection result storage means in association with the scanning distance on the flaw detection surface 53 of both probes 12. Further, flaw detection images (see FIG. 4B) derived corresponding to the defect upper end signal Sig1 and the defect lower end signal Sig2 appearing in the received waveform and the scanning distance are displayed on the display means 32 of the ultrasonic flaw detector 30. Is done.

  Here, the defect upper end signal Sig1 (or defect lower end signal Sig2) is transmitted from the transmission probe 12a, propagates through the inspection target member 50, and is diffracted or reflected by the defect upper end CLa (or defect lower end CLb). This refers to an ultrasonic reception signal (reception waveform) received by the reception probe 12b without being diffracted or reflected by other parts.

  When scanning in the first arrangement of both probes 12 is thus completed, the arrangement of both probes 12 is changed, and scanning is performed again with the changed arrangement.

  Specifically, the change in the arrangement of the two probes 12 is performed as shown in FIGS. 5 (a) to 5 (c). One probe (reception probe) in the first arrangement is used. The relative position of the probes 12a and 12b is changed along the orthogonal direction (the direction in which the probes 12 are arranged) while maintaining the position of the probe 12b on the flaw detection surface 53. In both the probes 12 after the change of the arrangement, the transmission probe 12a is arranged on the surface of the nozzle 52 (nozzle flaw detection surface 52a), and the reception probe 12b is on the surface of the shell 51 (shell flaw detection surface 51a). Has been placed.

  In the present embodiment, the transmitting probe (one) 12a in both probes 12 is thus arranged on the nozzle flaw detection surface 52a, and the receiving probe (the other) 12b is arranged on the shell flaw detection surface 51a. This arrangement is referred to as a second arrangement. In the second arrangement, the arrangement of the probes 12 may be interchanged as in the first arrangement. In other words, the reception probe 12b may be disposed on the nozzle flaw detection surface 52a, and the transmission probe 12a may be disposed on the shell flaw detection surface 51a.

  In this second arrangement, the inspected portion 55 is scanned in the same manner as in the first arrangement, and the obtained received waveform (see FIG. 6A) is transmitted to the ultrasonic flaw detector 30. Similarly to the above, the flaw detection image (see FIG. 6B) derived based on the defect upper end signal Sig1 and the defect lower end signal Sig2 appearing in the received waveform and the scanning distance or the like is displayed on the display means 32 of the ultrasonic flaw detector 30. Is displayed.

  As described above, the arrangement of the probes 12 is changed, and the received waveforms obtained by performing the scanning are analyzed by the ultrasonic flaw detector 30 and the analyzing calculator 40, whereby the inspected portion 55 The presence / absence of a defect CL and the position where the defect exists are detected. This analysis will be described below with reference to FIGS. 7 (a) to 8 as well.

  The ultrasonic flaw detector 30 determines whether or not a signal from the defect CL is included in the reception waveform obtained in the scan in the first arrangement from the reception probe 12b. When it is determined that the signal from the defect CL is included, the length of the defect CL along the inspected portion 55 based on the scanning distance and the time during which it is determined that the defect signal is included, That is, the defect length L is obtained.

  Specifically, both the probes 12 are scanned along the inspected portion 55, and the upper and lower ends of the defect are displayed on the flaw detection image (see FIGS. 4B and 6B). The left and right ends of the defect upper end CLa and the lower end CLb on the flaw detection image are arcuate, and the length of the straight line portion excluding the arcuate portion is the defect length L. Specifically, a parabolic cursor corresponding to the arrangement of the probes 12 and the time of the detected defect signal is displayed on the flaw detection image, and the curvature of the edge of the detected defect image and the curvature of the parabolic cursor are determined. A defect length L is derived by measuring the positions of the left and right ends using the coincident position as an end in the length direction of the defect.

  After the defect length L is derived, the defect CL in the inspected portion 55 is detected based on the ultrasonic waves respectively received by the reception probe 12b in the scans in the first and second arrangements. Potential positions where there is a possibility that a portion where the ultrasonic wave is diffracted or reflected are derived. Then, based on each possibility position in the first arrangement and the second arrangement, an accurate existence position in the inspected portion 55 of the portion where the ultrasonic wave is diffracted or reflected in the defect CL is derived. Using the existence position thus derived, the length of the defect CL in the direction orthogonal to the inspected part 55, that is, the defect height H is obtained.

  Specifically, for example, the existence position of the defect CL in the inspected portion 55 is derived as follows.

  First, based on the received waveform (ultrasonic wave) received by the receiving probe 12b, the propagation distance of ultrasonic waves (first defect propagation distance) from the transmitting probe 12a to the receiving probe 12b through a predetermined portion of the defect CL. ) Specifically, the ultrasonic wave that is diffracted or reflected from the transmitting probe 12a at the predetermined portion of the defect CL (in this embodiment, the upper end CLa or the lower end CLb of the defect CL) and reaches the receiving probe 12b. The defect signal propagation time t1 or t2 (see FIGS. 4A and 6A) is obtained, and the first defect propagation is determined from the defect signal propagation time t1 or t2 and the propagation speed of the ultrasonic wave in the inspection target member 50. Find the distance.

  Then, the ultrasonic wave diffracted from the transmission probe 12a to the reception probe 12b by being diffracted at the virtual point Vp (see FIG. 7A) in the inspection target member 50 (specifically, the inspected portion 55). A rotating ellipse composed of a locus of virtual points when the transmission probe 12a transmits ultrasonic waves in various directions to the flaw detection surface 53 in a state where the propagation distance (PS1 + PS2) coincides with the first defect signal propagation distance. Find a face.

  A first line that intersects the spheroid and a plane that passes through both the probes 12a and 12b and is orthogonal to the flaw detection surface 53 (the locus analysis plane (the paper surface in FIGS. 7A and 7B)). The locus Rc1 is obtained. The first locus Rc1 is configured by an elliptic curve, and there is a possibility that a predetermined portion of the defect CL in the inspected portion 55 (in this embodiment, the upper end CLa or the lower end CLb of the defect CL) may exist. The two first loci Rc1 corresponding to the defect upper end CLa and the lower end CLb are obtained.

  Similarly, the second existence possibility position, that is, the second locus Rc2 is obtained based on the received waveform obtained in the scanning with the second arrangement.

  Using the first locus Rc1 and the second locus Rc2 thus obtained, the intersection N1 between the first and second locus Rc1, Rc2 corresponding to the defect upper end CLa, and the defect lower end CLb. The intersection N2 between the first and second locus Rc1, Rc2 is obtained. By obtaining the upper end position and the lower end position of the defect CL in the inspected portion 55 from the intersections N1 and N2, the upper end position and the lower end position of the defect CL in the inspected portion 55 can be detected with high accuracy.

  Furthermore, the defect height H of the defect CL is accurately (accurately) obtained by using the positions of the accurate defect upper end CLa and lower end CLb in the inspected portion 55.

  Ultrasonic flaw detection was performed using the ultrasonic flaw detection method and the ultrasonic flaw detection apparatus 10 according to the above embodiment. As shown in FIG. 9, a specimen having a thickness of 200 mm simulating the nozzle weld was used as the specimen Ex. This test body is made of carbon steel, and the inner surface is formed by overlay welding of stainless steel. The thickness of the portion corresponding to the nozzle 52 in the above embodiment is 96 mm, and the portion corresponding to the shell 51 is The thickness is 200 mm. Artificial defects ACL1 to ACL3 are formed in a portion corresponding to the welded portion We in the embodiment.

  These artificial defects ACL1 to ACL3 are slit-like artificial defects that simulate cracks formed in the specimen Ex, and are provided on the outer surface, the inner surface, and the inner portion of the portion corresponding to the welded portion We in the above-described embodiment. It has been. In addition, overlay welding is performed on the inner surface portion of the specimen Ex.

  The size (dimensions) of the outer surface defect ACL1 and the inner surface defect ACL2 provided on the outer surface and the inner surface is 5 mm in height and 10 mm in length. The internal defect ACL3 provided inside has a height of 14 mm and a length of 14 mm. The height of the artificial defects ACL1 to ALC3 is the length in the defect height direction, and the length of the artificial defects ACL1 to ACL3 is the length in the defect length direction.

  The test body Ex is scanned in the first arrangement and in the second arrangement under a plurality of conditions in which the distance from each probe to the part (inspected part) corresponding to the welded part is changed. Each scan was performed. Further, the first and second loci were obtained from the scanning results in the first and second arrangements under these various conditions, and the defect height was derived from the intersection. The results are shown in Table 1.

  From this result, it can be confirmed that all defects have been detected.

  In the above results, the defect length and the defect height are both larger in the measured values than the actual sizes (actually measured values) of the artificial defects ACL1 to ACL3. In the measurement of defect dimensions, the fact that the measured value is larger than the actually measured value (actual dimension) is evaluated on the safety side in the industrial field.

  From the above, the usefulness of the defect detection ability and the dimension measurement ability of the nozzle weld in the ultrasonic flaw detection method and ultrasonic flaw detection apparatus could be confirmed.

  Note that the ultrasonic flaw detection method and the ultrasonic flaw detection apparatus 10 according to the present invention are not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention. .

  For example, in the above-described embodiment, when the defect CL is detected, the scan in the first arrangement and the scan in the second arrangement are sequentially performed, but after the scan in the second arrangement is performed. Even when scanning is performed in the first arrangement, it is possible to detect defects with the same accuracy.

  Further, as shown in FIGS. 10A and 10B, the first (or second) arrangement in the above-described embodiment (the position of the solid line in FIGS. 10A and 10B). After scanning, the transmitting probe 12a is covered on the flaw detection surface 51a (or 52a) of the same member in which both the probes 12a and 12b are arranged in the first (or second) arrangement. The 1a (or 2a) arrangement (the position of the two-dot chain line in FIGS. 10 (a) and 10 (b)) moved in the direction orthogonal (or substantially orthogonal) to the inspection unit 55 is used. You may make it scan by the arrangement of (or 2a).

  In this case, when obtaining the intersection N1 (or N2) of the first and first a (or second and second a) loci Rc1, Rc1a (or Rc2 and Rc2a) corresponding to the upper and lower ends of the defect, However, the height of the defect can be obtained from the distance between the intersections N1 and N2.

  In the above-described embodiment, the arrangement of the probes 12 is changed and scanning is performed in different arrangements. However, in the case where only the presence / absence of the defect CL and the defect length L are detected. If there is, it can be detected by scanning in one arrangement (for example, only the first arrangement or only the second arrangement).

  In the above-described embodiment, a member in which a cylindrical nozzle 52 is joined (welded) to a cylindrical circumferential shell 51 in a direction orthogonal to the surface of the shell 51 is used as the inspection target member 50. However, it need not be limited to this. For example, as shown in FIG. 16A and FIG. 16B, a member joined so that the axis of the nozzle 52 is offset in the axial direction and the circumferential direction of the shell 51 may be used. Further, as shown in FIGS. 16C and 16D, the surface may be a shell 51 having a spherical shape (curved surface), or the axis of the nozzle may be offset. Further, as shown in FIGS. 16 (e) to 16 (g), a member constituted by a so-called T joint, a corner joint, or a cross joint may be used.

  That is, according to the ultrasonic flaw detection method and the ultrasonic flaw detection apparatus according to the present invention, the welded portion We in the member described in FIGS. 16A to 16G and the welded portion including the welded portion We. It is possible to detect the presence / absence of a defect in the inspected part extending along We, the position where the defect exists, and the size of the defect.

1 is a schematic configuration diagram of an ultrasonic flaw detector according to an embodiment. In the ultrasonic flaw detector according to the embodiment, (a) is a side view of a probe including a shoe having a smooth contact surface, and (b) is a rear view of the shoe having a smooth contact surface. is there. In the ultrasonic flaw detection method according to the embodiment, (a) is a perspective view of a member to be inspected in which both probes are in the first arrangement, and (b) is an arrangement of both probes in FIG. 3 (a). It is a partial expanded sectional view in a position, and (c) is a top view of Drawing 3 (a). In the ultrasonic flaw detection method according to the embodiment, (a) shows a received waveform in the first arrangement, and (b) is a flaw detection image in the first arrangement. In the ultrasonic flaw detection method according to the embodiment, (a) is a perspective view of a member to be inspected in which both probes are in the second arrangement, and (b) is an arrangement of both probes in FIG. 5 (a). It is a partial expanded sectional view in a position, and (c) is a top view of Drawing 5 (a). In the ultrasonic flaw detection method according to the embodiment, (a) shows a received waveform in the second arrangement, and (b) is a flaw detection image in the second arrangement. In the ultrasonic flaw detection method according to the embodiment, (a) is an explanatory diagram of the analysis process of the defect location in the first arrangement performed by the analysis computer, and (b) is a second diagram performed by the analysis computer. It is explanatory drawing of the analysis process of the defect presence position in arrangement | positioning. It is explanatory drawing of the analysis process of the defect height which the calculator for analysis performs in the ultrasonic flaw detection method which concerns on the embodiment. It is a partial expanded sectional view which shows the position of the artificial defect in a test body. (A) in the ultrasonic flaw detection method which concerns on other embodiment is a partial expanded sectional view which shows arrangement | positioning of 1st and 1a, (b) is a partial expanded sectional view which shows arrangement | positioning of 2nd and 2a. (A) is explanatory drawing which shows the propagation path of an ultrasonic wave in the case of detecting the defect inside a welding part at the time of butt-welding two flat steel plates using a TOFD method, (b) is a received waveform. (C) is a figure which shows the scanning direction of both probes. (A) in the case of detecting a defect in a joint portion of a member to be inspected in which a cylindrical nozzle is joined to a cylindrical shell of a cylindrical surface by using the CG-TOFD method is an inspection subject in which both probes are arranged. It is a perspective view of a member, (b) is the elements on larger scale in the arrangement position of both probes. (A) is a perspective view of a member to be inspected in which a pair of probes are arranged in parallel along the part to be inspected, and (b) is a partially enlarged cross-sectional view at an intermediate position between the two probes. c) is a partially enlarged plan view of the arrangement positions of the two probes. (A) And (b) is a figure which shows an example of the test object member by which the movement of a probe is controlled. It is a figure which shows arrangement | positioning and the scanning direction of both the probes in the to-be-inspected member by which the cylindrical nozzle is joined to the cylindrical shell of the surrounding surface shape. (A) thru | or (g) is a figure which illustrates the to-be-inspected member which can be flaw-detected with the ultrasonic flaw detection method and ultrasonic flaw detection apparatus which concern on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic flaw detector 12 Both probes 12a Transmission probe 12b Reception probe 53 Test surface 55 Inspected part CL Defect

Claims (9)

Ultrasonic flaw detection in which an ultrasonic wave is propagated in a portion to be inspected including a joint portion of the first member and the second member joined to each other, and a defect in the portion to be inspected is detected by receiving the propagated ultrasonic wave A method,
On the flaw detection surface formed by the first specific surface of the first member and the second specific surface of the second member connected via the joint so as to cross each other, the flaw detection surface A direction in which the transmitting probe for transmitting the ultrasonic wave and the receiving probe for receiving the transmitted ultrasonic wave from the flaw detection surface are orthogonal or substantially orthogonal to the part to be inspected extending along the joint. Placed side by side,
The probes are moved toward the inspected portion while moving both probes along the inspected portion along the inspected portion while maintaining the distance from the portion where the first and second specific surfaces intersect each other. And transmitting ultrasonic waves from the transmitting probe and receiving a ultrasonic wave diffracted or reflected by the defect with the receiving probe when a defect has occurred in the inspected portion. Flaw detection method. The ultrasonic flaw detection method according to claim 1,
The ultrasonic flaw detection method, wherein both the transmission probe and the reception probe are arranged on the first specific surface or the second specific surface. The ultrasonic flaw detection method according to claim 1,
One of the transmitting probe and the receiving probe is disposed on the first specific surface, and the other is disposed on the second specific surface, and the ultrasonic flaw detection method is characterized in that . Ultrasonic flaw detection in which an ultrasonic wave is propagated in a portion to be inspected including a joint portion of the first member and the second member joined to each other, and a defect in the portion to be inspected is detected by receiving the propagated ultrasonic wave A method,
On the flaw detection surface formed by the first specific surface of the first member and the second specific surface of the second member connected via the joint so as to cross each other, the flaw detection surface A direction in which the transmitting probe for transmitting the ultrasonic wave and the receiving probe for receiving the transmitted ultrasonic wave from the flaw detection surface are orthogonal or substantially orthogonal to the part to be inspected extending along the joint. To the first arrangement,
The probes are moved toward the inspected portion while moving both probes along the inspected portion along the inspected portion while maintaining the distance from the portion where the first and second specific surfaces intersect each other. And transmitting the ultrasonic wave from the transmission probe and receiving the ultrasonic wave diffracted or reflected by the defect when the defect is generated in the inspection target part. Scan,
The relative position of both probes in the first arrangement is changed along the direction orthogonal or substantially orthogonal to the second arrangement,
An ultrasonic flaw detection method comprising scanning the part to be inspected in the second arrangement. The ultrasonic flaw detection method according to claim 4,
There may be a portion where the ultrasonic wave is diffracted or reflected in the defect in the inspected part based on the ultrasonic waves respectively received by the receiving probe in the scanning in the first arrangement and the second arrangement. Each potential position of existence is derived,
The superposition characterized in that the existence position in the inspected part of the ultrasonic diffraction or reflection part in the defect is derived based on the existence possibility positions in the first arrangement and the second arrangement. Sonic flaw detection method. The ultrasonic flaw detection method according to claim 4 or 5,
In the first arrangement, both the transmitting probe and the receiving probe are arranged on the first specific surface or the second specific surface,
In the second arrangement, one of the transmission probe and the reception probe is arranged on a first specific surface, and the other is arranged on a second specific surface. Ultrasonic flaw detection method. The ultrasonic flaw detection method according to claim 4 or 5,
In the first arrangement, one of the transmission probe and the reception probe is arranged on a first specific surface and the other is arranged on a second specific surface,
In the second arrangement, the transmission probe and the reception probe are both arranged on the first specific surface or the second specific surface. The ultrasonic flaw detection method according to claim 4 or 5,
In the first arrangement, one of the transmission probe and the reception probe is arranged on a first specific surface and the other is arranged on a second specific surface,
In the second arrangement, the transmitting probe or the receiving probe is arranged at a position moved on the same plane from the position arranged in the first arrangement along the orthogonal or substantially orthogonal direction. An ultrasonic flaw detection method characterized by: Ultrasonic flaw detection in which an ultrasonic wave is propagated in a portion to be inspected including a joint portion of the first member and the second member joined to each other, and a defect in the portion to be inspected is detected by receiving the propagated ultrasonic wave A device,
On the flaw detection surface formed by the first specific surface of the first member and the second specific surface of the second member connected via the joint so as to cross each other, along the joint A transmitting probe for transmitting the ultrasonic waves to the flaw detection surface arranged in a direction orthogonal to or substantially orthogonal to the part to be inspected extending, and receiving the transmitted ultrasonic waves from the flaw detection surface A receiving probe;
Both probes move toward the inspected portion while moving on the flaw detection surface along the inspected portion in a state where the distances from the portions where the first and second specific surfaces intersect each other are maintained. The transmitting probe transmits the ultrasonic wave, and when a defect occurs in the inspection target portion, the ultrasonic wave diffracted or reflected by the defect is received by the receiving probe, and the received signal is An ultrasonic flaw detector comprising: defect detection means for detecting a defect in the inspected part.

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