JP2006349486A - Ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ultrasonic probe, capable of performing ultrasonic flaw detection over the range from the region directly under the recessed curved surface of an inspection target to a deep position in the recessed curved surface of the inspection target, without detection failures of flaws, when the internal ultrasonic flaw detection of the recessed curved surface is performed, by making ultrasonic beam enter the recessed curved surface of the inspection target, from the recessed curved surface of the inspection target. <P>SOLUTION: The ultrasonic probe 1 is constituted so as to allow the ultrasonic beam 10 to enter the inside of the recessed curved surface 20a of the inspection target 20, from the recessed curved surface 20a of the inspection target 20, to perform ultrasonic flaw detection of the inside of the recessed curved surface 20a, and is equipped with vibrator parts 2 and 4 for transmitting and receiving an ultrasonic wave, the delay material parts 3 and 5, provided in contact with the vibrator parts and a flaw detection shoe 7 having an inspection target contact protruded curved surface 7a for comprising a material, having the same ultrasonic propagation speed as the inspection target 20 and having a radius of curvature almost the same to that of the recessed curved surface 20a and brought into contact with the recessed curved surface 20a at the time of flaw detection and the delay material contact plane 7b, brought into contact with the planar undersurfaces of the delay material parts. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe used as a sensor when performing ultrasonic flaw detection inside a concave curved surface by causing an ultrasonic beam to enter the concave curved surface of the object to be inspected.

  In structures such as a crankshaft of a ship in which strength is important, the maximum defect size allowed in the strength design is defined, and it is necessary to confirm the presence or absence of defects and to confirm the size in the inspection. Ultrasonic flaw detection is widely used for inspection of defects inside the structure. In this ultrasonic flaw detection, an ultrasonic probe is brought into contact with the surface of the object to be inspected through a contact medium such as water, oil, glycerin, and an ultrasonic beam is incident on the inside of the object to be inspected from the surface of the object to be inspected. By observing a reflected wave (echo) from the defect, the presence and size of the defect is evaluated.

  In general, an ultrasonic probe used for ultrasonic flaw detection is a transducer unit that transmits and receives ultrasonic waves, and a delay material unit that is provided in contact with the transducer unit (a material made of acrylic resin is widely used). And). Depending on the shape of the delay material part, the delay material part may be used for an oblique angle probe in which ultrasonic waves are incident obliquely forward, for a surface wave probe that is transmitted along the surface of the object to be inspected, for a vertical probe that is incident in the vertical direction, etc. is there. In general, the delay material portion of the ultrasonic probe has a flat contact portion that contacts the object to be inspected during flaw detection. For this reason, when the ultrasonic probe is brought into contact with the concave curved surface of the object having a concave curved surface, a gap (air layer) is generated between the ultrasonic probe and the concave curved surface, and the ultrasonic wave is generated. There is a problem that it is reflected by the air layer and does not enter the object to be inspected.

  Accordingly, in order to solve the problem of the gap generated between the ultrasonic probe and the concave curved surface of the object to be inspected, Japanese Patent Laid-Open No. 11-337537 proposes an ultrasonic probe shown in FIG. (Prior Art 1). The ultrasonic probe 61 used in the surface wave method has an ultrasonic wave oscillated from an ultrasonic oscillator 64 and has a concave curved surface 62a (a radius of curvature of 250 to 750 mm) through a flaw detection shoe 63. ), The ultrasonic oscillator 64 is attached to the flaw detection shoe 63 so that the refraction angle thereof becomes 90 °, and the inspection object concave portion of the flaw detection shoe 63 is recessed. The shape of the surface in contact with the curved surface 62a is a convex curved surface, and the curvature radius of the convex curved surface is smaller than the curvature radius of the inspected object concave curved surface 62a.

  In addition, by submerging the object to be inspected or locally immersing the concave curved surface portion of the object to be inspected, the gap between the ultrasonic probe and the object to be inspected is filled with water as a contact medium. There is also known a method in which an ultrasonic wave is incident on an object to be inspected through water as a contact medium (prior art 2).

Further, in Japanese Patent Application Laid-Open No. 11-304774, as shown in FIG. 8, a flexible vibrator portion 72 and a flexible finger sac shape for attaching the vibrator portion 72 to the fingertip 90 are provided. An ultrasonic probe 71 composed of a fixed portion 73 has been proposed. According to this ultrasonic probe 71, the transducer portion 72 is deformed in accordance with the concave shape of the inspection object 80 so that no gap is generated between the inspection object 80 and the ultrasonic probe 71. (Prior Art 3).
JP 11-337537 A (2nd page, FIG. 1) JP-A-11-304774 (second page, FIG. 1)

  In the above-described conventional techniques 1 to 3, the problem that a gap (air layer) is generated between the concave curved surface of the object to be inspected and the ultrasonic probe and the ultrasonic wave is reflected by the air layer can be solved. it can.

  However, when performing an ultrasonic flaw detection inside the concave curved surface by making an ultrasonic beam incident on the concave curved surface of the object to be inspected, the radius of curvature of the concave curved surface of the object to be inspected is 250 in the prior art 1. In addition to the above-mentioned problem that a gap is generated between the concave curved surface and the ultrasonic probe when the diameter is considerably small (about 10 mm) compared to 750 mm or the like (when the curvature is large and steep). The inventors have found that there is a serious problem from the results of experiments and detailed studies.

  FIG. 5 is a diagram for explaining the problem of the present invention. In an ultrasonic probe having an acrylic resin delay member having a convex contact curved surface, an object to be inspected from the ultrasonic probe is shown. It is a figure which shows typically the mode of incidence | injection of the ultrasonic beam into the concave curved surface of a test body.

  In FIG. 5, 20 is a general carbon steel inspection object having a concave curved surface with a curvature radius of 12 mm as a fillet part, and 31 is an ultrasonic probe. The ultrasonic probe 31 is a two-vibrator vertical probe (two-divided vertical probe), and includes a transducer unit 32 and an acrylic resin delay material unit provided in contact with the transducer unit 32. 33. Further, the acrylic resin delay member 33 has a curvature radius substantially the same as that of the concave curved surface of the object to be inspected on the tip side thereof, and contacts the concave curved surface of the object to be inspected 20 at the time of flaw detection. 33a.

  Then, the test object contact convex curved surface 33a of the ultrasonic probe 31 is brought into contact with the concave curved surface of the test object 20 made of general carbon steel with a radius of curvature of 12 mm through a contact medium such as glycerin to form a concave curved surface. When ultrasonic inspection is performed inside, the inspection performance is extremely low compared to ultrasonic inspection using an ultrasonic probe having a flat surface shape with an ultrasonic probe having an inspection object contact plane. End up.

  The reason is that, as shown in FIG. 5, the ultrasonic beam is refracted at the interface between the ultrasonic probe 31 and the concave curved surface of the inspection object 20 (the curved interface having a small radius of curvature). The longitudinal wave sound speed in the object 20 to be inspected made of general carbon steel is about 5900 m / s, whereas the longitudinal wave sound speed in the acrylic resin delay member 33 made of acrylic resin is 2700 m / s. s. From Snell's law, for example, an ultrasonic beam incident from an oblique angle with an incident angle of 10 degrees is bent and propagated by about 12 degrees in the 22-degree direction, and an ultrasonic beam incident at an incident angle of 20 degrees is 47. Propagate by bending about 27 degrees in the 7 degree direction. The result schematically is an ultrasonic beam T in FIG. As shown in FIG. 5, for example, when the incident angle is 10 degrees, the ultrasonic beam T converges in the vicinity of 9.8 mm immediately below the concave curved surface of the object 20 to be inspected, but is widely dispersed in a portion deeper than that. Yes. For this reason, an ultrasonic beam having a sufficient sound pressure does not reach a defect at a deep position, so that it is difficult to perform flaw detection with a good S / N ratio, and defect detection leaks. This has been confirmed experimentally, and as an artificial defect, specimens each having a flat bottom hole with a diameter of 1 mm and a depth of 10 to 50 mm from the concave surface to a depth of 10 to 50 mm are manufactured at an ultrasonic probe. As a result of flaw detection by 31, it was possible to detect the artificial defect located at a depth of 10 mm from the concave curved surface, but no clear echo could be observed for the artificial defect located deeper than that.

  FIG. 6 is a diagram for explaining the problem of the present invention, and schematically shows an incident state of an ultrasonic beam from the ultrasonic probe into the concave curved surface of the object to be inspected by the local water immersion method. FIG.

  In FIG. 6, 20 is a general carbon steel inspection object having a concave curved surface with a curvature radius of 12 mm as a fillet portion, and 41 is an ultrasonic probe. The ultrasonic probe 41 is a dual transducer vertical probe (two-divided vertical probe), and includes a transducer section 42 and an acrylic resin delay material section provided in contact with the transducer section 42. 43. In addition, the acrylic resin delay member 43 has a flat surface 43a on the tip side. That is, the ultrasonic probe 41 has a general shape as an ultrasonic probe. Reference numeral 50 denotes a local water immersion in which the space between the concave curved surface of the inspection object 20 and the ultrasonic probe 41 is filled with water.

  The refraction of the ultrasonic beam at the interface also occurs in the ultrasonic flaw detection by the ultrasonic probe 41 in the local water immersion method as shown in FIG. The longitudinal wave sound velocity in water is 1480 m / s, and the refraction angle is larger than the longitudinal wave sound velocity (2700 m / s) in the acrylic resin delay member 33 in FIG. 5, as shown in FIG. In addition, for example, when the incident angle is 10 degrees, the ultrasonic beam T converges in the vicinity of 3.8 mm immediately below the concave curved surface of the inspection target 20, but the degree of divergence is intense.

  In this way, when performing ultrasonic flaw detection inside a concave curved surface by making an ultrasonic beam incident from the concave curved surface of the specimen to be inspected, the radius of curvature of the concave curved surface of the specimen to be inspected is as small as about 10 mm. In this case, the ultrasonic beam is refracted by Snell's law at the curved interface. In addition, when the flexible vibrator shown in FIG. 8 of the prior art 3 described above is adapted to the object to be inspected, the ultrasonic beam propagates and spreads in the normal direction of the surface of the object to be inspected in the same manner. End up. Furthermore, it cannot be said that the vibrator part itself changes according to the shape of the inspection object from the viewpoint of quantifying the defect size. In general, in ultrasonic flaw detection, an echo level from an artificial defect having a known dimension as a test piece is compared with an echo level from an actual defect, and the defect size is specified. The premise is that the ultrasonic transducer has invariable characteristics in transmission and reception and has reproducibility. However, in the prior art 3, the change in the shape of the vibrator portion according to the shape of the object to be inspected is inconvenient because it can be a major factor that impairs reproducibility.

  An object of the present invention is to perform ultrasonic flaw detection inside a concave curved surface by making an ultrasonic beam incident on the concave curved surface of the object to be inspected and to detect defects from a position immediately below the concave curved surface to a deep position inside the concave curved surface. An object of the present invention is to provide an ultrasonic probe capable of performing ultrasonic flaw detection.

  In order to solve the above problems, the present invention takes the following technical means.

  According to the first aspect of the present invention, in an ultrasonic probe that performs ultrasonic flaw detection inside a concave curved surface by causing an ultrasonic beam to enter the concave curved surface of the object to be inspected, vibration for transmitting and receiving ultrasonic waves. A sub-part, a delay member provided in contact with the transducer part, and a material having the same ultrasonic propagation velocity as the object to be inspected, having a curvature radius substantially the same as the concave curved surface, and flaw detection An ultrasonic wave comprising: a test object contact convex curved surface that is sometimes brought into contact with the concave curved surface; and a flaw detection shoe having a delay material contact plane that is in surface contact with the planar lower surface of the delay material portion. It is a probe.

  According to a second aspect of the present invention, in the ultrasonic probe according to the first aspect, the flaw detection shoe has a length from the delay material contact plane to the inspected object contact convex curved surface from the concave curved surface of the inspected object. It is characterized in that it is longer than the flaw detection area length.

  The ultrasonic probe of the present invention includes a transducer part, a delay member part, and a flaw detection shoe, and the flaw detection shoe is made of a material having the same ultrasonic propagation velocity as that of the inspection object, and the inspection object. The curved surface of the object to be inspected is brought into contact with the concave curved surface at the time of flaw detection, and the flat bottom surface of the delay member provided in contact with the vibrator portion is in surface contact. And a retarder contact plane.

  Therefore, the delay material contact plane of the flaw detection shoe is brought into surface contact with the flat bottom surface of the delay material portion, and the flaw detection shoe has a convex curved surface that is in contact with the test subject, so that there is a gap between the concave curved surface of the test subject. Since the flaw detection shoe is made of a material having the same ultrasonic propagation velocity as that of the object to be inspected, an ultrasonic beam according to Snell's law is formed at the interface between the flaw detection shoe and the concave curved surface of the object to be inspected. Can be prevented from occurring. As a result, the ultrasonic beam emitted from the delay material part advances straight without being refracted midway from the inside of the flaw detection shoe to the inside of the concave curved surface of the object to be inspected.

  Therefore, the ultrasonic probe of the present invention can ensure the same flaw detection performance as that of ultrasonic flaw detection on a flat surface by substantially flattening the concave curved surface of the inspection object with the flaw detection shoe. Ultrasonic flaw detection can be performed without detecting any defect from directly under the concave curved surface of the body to a deep position inside the concave curved surface. In addition, by making the length of the flaw detection shoe of the ultrasonic probe longer than the flaw detection area length from the concave surface of the object to be inspected, it is affected by multiple echoes at the interface between the flaw detection shoe and the object to be inspected. And echoes from defects can be observed.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a configuration diagram schematically showing an ultrasonic probe according to an embodiment of the present invention, FIG. 2 is a front view of the ultrasonic probe shown in FIG. 1, and FIG. 3 is an ultrasonic probe shown in FIG. It is a figure which shows typically the mode of incidence | injection of the ultrasonic beam from the child | child to the inside of the concave curved surface of the to-be-inspected object.

  In FIG. 1, 20 is a test object. In this embodiment, the inspection object 20 is a general carbon steel inspection object having a concave curved surface 20a having a curvature radius of 12 mm as a fillet portion. When a fillet portion is applied to a machine part (structure), the design stress at that portion is often large. Therefore, the allowable defect size at the fillet portion is also small, and ultrasonic flaw detection may be required as to whether there are cracks or inclusion defects. In this embodiment, the ultrasonic probe 1 is a dual transducer vertical probe (two-divided vertical probe) having a frequency of 10 MHz.

  1 and 2, reference numeral 2 denotes a transmission vibrator, and reference numeral 3 denotes a block-shaped transmission delay material made of acrylic resin that is in contact with the transmission vibrator 2. Reference numeral 4 denotes a reception vibrator, and reference numeral 5 denotes a block-shaped reception delay material made of acrylic resin that is provided in contact with the reception vibrator 4. 6 is an acoustic separator, and the transmission delay material 3 and the reception delay material 5 are separated from each other so that the transmission vibrator 2 and the transmission delay material 3 are separated from the reception vibrator 4 and the reception delay material 5. It is provided between them. The transmission transducer 2 and the reception transducer 4 constitute a transducer unit that transmits and receives ultrasonic waves. Further, the transmission delay material 3 and the reception delay material 5 constitute a delay material portion provided in contact with the vibrator portion. Note that a case for housing the vibrator portion and the delay member portion is not shown.

  7 is a flaw detection shoe. The flaw detection shoe 7 is made of a material having the same ultrasonic propagation velocity as that of the inspected object 20, has a curvature radius substantially the same as the concave curved surface 20a, and is inspected to be in contact with the concave curved surface 20a of the inspected object 20 during flaw detection. It has a contact convex curved surface 7a and a delay material contact plane 7b that is in surface contact with the planar lower surfaces of the transmission delay material 3 and the reception delay material 5, and the transmission delay material 3 and It is fixed to the lower surface of the receiving delay material 5. In this embodiment, the flaw detection shoe 7 is made of general carbon steel, which is the same material as the inspection object 20, and the inspection object contact convex curved surface 7a of the inspection flaw 7 is a concave curved surface 20a having a curvature radius of 12 mm. Accordingly, a convex curved surface having substantially the same radius of curvature as the concave curved surface 20a is formed. In this case, the radius of curvature of the inspected object contact convex curved surface 7a does not have to be exactly the same as the radius of curvature of the concave curved surface 20a of the inspected object 20, and satisfies an allowable range of about ± 10%. In the ultrasonic probe 1, it is preferable that the inspection object contact convex curved surface 7a of the flaw detection shoe 7 is brought into contact with the concave curved surface 20a of the inspection object 20 via a contact medium such as glycerin.

  According to the ultrasonic probe 1 configured as described above, the delay material contact plane 7b of the flaw detection shoe 7 is brought into surface contact with the planar lower surfaces of the transmission delay material 3 and the reception delay material 5, and the flaw detection shoe. Since the test object 7 has the convex contact surface 7a to be inspected, it is possible to eliminate a gap between the test object 20 and the concave curved surface 20a, and the flaw detection shoe 7 has the same ultrasonic wave propagation as the test object 20. By being made of a material having speed, it is possible to eliminate the occurrence of refraction of the ultrasonic beam by Snell's law at the interface between the flaw detection shoe 7 and the concave curved surface 20a of the inspection object 20. As a result, the ultrasonic beam 10 emitted from the transmission delay material 3 advances straight without being refracted midway from the inside of the flaw detection shoe 7 to the inside of the concave curved surface 20a of the object 20 as shown in FIG.

  Therefore, according to the ultrasonic probe 1, by substantially flattening the concave curved surface 20a of the object 20 to be inspected by the flaw detection shoe 7, flaw detection performance similar to that of ultrasonic flaw detection on a flat surface can be ensured. In addition, ultrasonic flaw detection can be performed without any defect detection over a deep position inside the concave curved surface 20a from directly under the concave curved surface 20a of the object 20 to be inspected.

  FIG. 4 is a diagram schematically showing an echo by the ultrasonic probe shown in FIG.

  According to the ultrasonic probe 1, echoes from the defect 21 are observed as shown in FIG. 4 is a display called a so-called A scope, the horizontal axis represents time, that is, the ultrasonic wave propagation position (depth), and the vertical axis represents the ultrasonic echo level. In FIG. 4, an echo from the surface of the inspection object is observed. This is an echo caused by the reflection of the ultrasonic beam at the interface between the flaw detection shoe 7 and the inspection object 20, and this repeats multiple reflections. Appear at equally spaced positions.

  In this case, the position of the multiple echoes at the interface between the flaw detection shoe 7 and the inspection object 20 is set by making the length of the flaw detection shoe 7 appropriate to the area to be flaw detection in the inspection object 20. Can be controlled, and can be discriminated from defect echoes. It is preferable that the flaw detection shoe 7 has a length from the delay material contact flat surface 7b to the inspection object contact convex curved surface 7a that is equal to or greater than a flaw detection region length from the concave curved surface 20a of the inspection object 20. According to the ultrasonic probe 1, a flat bottom hole having a diameter of 0.5 mm of an artificial defect located at a depth of 10 to 50 mm from the concave curved surface 20a can be detected with high accuracy.

1 is a configuration diagram schematically showing an ultrasonic probe according to an embodiment of the present invention. FIG. FIG. 2 is a front view of the ultrasonic probe shown in FIG. 1. It is a figure which shows typically the mode of incidence | injection of the ultrasonic beam from the ultrasonic probe shown in FIG. 1 in the inside of the concave curved surface of the to-be-inspected object. It is a figure which shows typically the echo by the ultrasonic probe shown in FIG. It is a figure for explaining the subject of the present invention, Comprising: In the ultrasonic probe provided with the delay material part made from acrylic resin which has a to-be-inspected object contact convex curve, of the to-be-inspected object from this ultrasonic probe It is a figure which shows typically the mode of incidence | injection of the ultrasonic beam into a concave curved surface inside. It is a figure for demonstrating the subject of this invention, Comprising: It is a figure which shows typically the mode of incidence | injection of the ultrasonic beam from the ultrasonic probe in the concave curved surface of the to-be-inspected object by a local water immersion method. is there. It is a block diagram which shows the conventional ultrasonic probe. It is a block diagram which shows another conventional ultrasonic probe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe 2 ... Transmission vibrator 3 ... Transmission delay material (made of acrylic resin)
4 ... Receiving vibrator 5 ... Receiving delay material (made of acrylic resin)
6 ... Acoustic separator 7 ... Flaw detection shoe (general carbon steel)
7a: Convex curved surface of object to be inspected 7b: Contact surface of delay material 10 ... Ultrasonic beam 20 ... Object to be inspected (general carbon steel)
20a ... concave curved surface

Claims (2)

  In an ultrasonic probe for performing ultrasonic flaw detection inside a concave curved surface by causing an ultrasonic beam to enter the concave curved surface of the object to be inspected, a transducer unit for transmitting and receiving ultrasonic waves, and the transducer A delay member provided in contact with the part, and a material having the same ultrasonic propagation velocity as that of the object to be inspected, having a curvature radius substantially the same as the concave curved surface, and contacting the concave curved surface during flaw detection An ultrasonic probe comprising: a test object contact convex curved surface; and a flaw detection shoe having a delay material contact plane in surface contact with the planar lower surface of the delay material portion.   2. The super-flaw according to claim 1, wherein the flaw detection shoe has a length from the delay material contact plane to the inspected object contact convex curved surface that is equal to or greater than a flaw detection area length from the concave curved surface of the inspected object. Sonic probe.

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