JP2009243959A - Ultrasonic probe and ultrasonic flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect existence of an internal defect in a deep spot inside a workpiece W with high accuracy, while reducing a noise echo. <P>SOLUTION: A vibrator 7 for transmitting and receiving an ultrasonic wave S is provided in a probe case 3, and a vibration surface of the vibrator 7 is constituted of assembly of propagation points k having an equal propagation time Tt of the ultrasonic wave S for arrival via the surface of the workpiece W after being radiated from a common focal point f inside the workpiece W. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe used for inspecting the presence or absence of an internal defect of an inspection object having a curved surface (for example, a round bar-shaped inspection object), and an internal defect of the inspection object having a curved surface. The present invention relates to an ultrasonic flaw detection method for inspecting the presence or absence of defects.

  For example, in the field of aero engines, round bar-shaped billets are used as a material for engine parts. Usually, before the billet is subjected to processing such as forging, the vibration surface has a spherical shape and ultrasonic waves are applied. An ultrasonic probe equipped with a transducer for transmitting and receiving is used to inspect for the presence of internal defects in a round bar-shaped billet that is an object to be inspected by a water immersion method.

  That is, as shown in FIG. 6, a round bar-shaped inspection object (billet) W is set in a predetermined position in the water tank T in a state of being immersed in the water L. Then, while moving the ultrasonic probe 101 along the axial direction of the inspection object W, the ultrasonic wave S transmitted from the transducer 103 in the ultrasonic probe 101 is incident on the inspection object W, and The ultrasonic wave S as a reflected wave is received by the vibrator 103. Thereby, the presence or absence of a reflected wave (reflection echo) due to the internal defect of the inspection object W, in other words, the presence or absence of the internal defect of the inspection object W can be inspected along the axial direction of the inspection object W. Here, the presence or absence of an internal defect of the inspection object W can be inspected over the circumferential direction of the inspection object W by rotating the inspection object W around the axis.

In addition, there exist some which are shown to patent document 1 and patent document 2 as a prior art relevant to this invention.
JP 2001-153847 A Japanese Patent Laid-Open No. 4-1666761

  By the way, the vibration surface of the transducer 103 in the conventional ultrasonic probe 101 has a spherical shape, and the surface of the inspection object W is curved, so that the inspection object with respect to the axial direction of the inspection object W is inspected. When the inclination angle φ of the longitudinal section of W is different, as shown in FIGS. 7A and 7B, the focal length of the ultrasonic wave S in the longitudinal section of the inspection object W is different. The transmitted ultrasonic wave S is not focused at one point inside the inspection object W, but is focused on a localized region. Therefore, when the internal defect of the inspection object W exists in a deep portion inside the inspection object W, the ultrasonic intensity of the reflected wave S due to the internal defect of the inspection object W becomes weak, and the internal defect of the inspection object W It becomes impossible to detect the reflected wave due to. Further, when the detection sensitivity of the ultrasonic wave S received by the transducer 103 is increased, noise echo increases, and the detection accuracy of the ultrasonic probe 101 deteriorates. That is, the conventional ultrasonic probe 101 has a problem that it is extremely difficult to accurately inspect for the presence or absence of an internal defect in a deep portion inside the inspection object W.

  Therefore, an object of the present invention is to provide an ultrasonic probe and an ultrasonic flaw detection method having a novel configuration that can solve the above-described problems.

  A first feature of the present invention is an ultrasonic probe used for inspecting the presence or absence of an internal defect of an inspection object having a curved surface, provided in the probe case and the probe case, A vibrator that transmits and receives ultrasonic waves, and a vibration surface (transmission / reception surface) of the vibrator is emitted from a common focal point inside the inspection object and reaches through the surface of the inspection object The gist is that the ultrasonic wave is composed of a set of propagation points having the same propagation time.

  According to the first feature, the ultrasonic wave transmitted from the vibrator is incident on the inspection object, and the ultrasonic wave as a reflected wave is received by the vibrator. Thereby, it is possible to inspect the presence or absence of a reflected wave (reflection echo) due to an internal defect of the inspection object, in other words, the presence or absence of an internal defect of the inspection object.

  Here, the vibration surface of the vibrator is constituted by a set of propagation points that are radiated from a common focal point inside the inspection object and reach the ultrasonic wave through the surface of the inspection object. Therefore, the focal lengths of the ultrasonic waves are equal in any longitudinal cross section having different inclination angles with respect to the axial direction of the inspection object, in other words, the ultrasonic waves transmitted from the vibrator are converted into the inspection object. It will be converged to one point inside. Thereby, even if the detection sensitivity of the ultrasonic wave received by the vibrator is not set high, sufficiently ensure the ultrasonic intensity of the reflected wave due to the internal defect in the deep part inside the inspection object. Can do.

  According to a second aspect of the present invention, an ultrasonic probe including a transducer for transmitting and receiving ultrasonic waves is used, and the ultrasonic wave transmitted from the transducer is incident on an inspected object having a curved surface. In the ultrasonic flaw detection method for inspecting the presence / absence of an internal defect in the inspection object by receiving ultrasonic waves as reflected waves by the vibrator, the vibration surface (transmission / reception surface) of the vibrator is the surface of the inspection object. The gist of the invention is that it consists of a set of propagation points that are radiated from a common focal point inside and reach the surface of the object to be inspected until the ultrasonic wave has the same propagation time.

  According to a second feature, the vibration surface of the vibrator is radiated from a common focal point inside the inspection object and propagates through the surface of the inspection object until the ultrasonic wave has the same propagation time. Therefore, the ultrasonic focal lengths are equal in any vertical cross section having different inclination angles with respect to the axial direction of the inspection object, in other words, the ultrasonic waves transmitted from the vibrator are inspected. It will converge to one point inside the object. Thereby, even if the detection sensitivity of the ultrasonic wave received by the vibrator is not set high, sufficiently ensure the ultrasonic intensity of the reflected wave due to the internal defect in the deep part inside the inspection object. Can do.

  According to the present invention, even if the detection sensitivity of the ultrasonic wave received by the vibrator is not set high, the ultrasonic wave intensity of the reflected wave due to the internal defect existing deep in the inspection object is sufficiently increased. Since it can be ensured, it is possible to inspect with high accuracy the presence or absence of an internal defect located deep inside the inspection object while reducing noise echo.

  An embodiment of the present invention will be described with reference to FIGS.

  Here, FIG. 1 (a) is a diagram for explaining the vibration surface of the transducer in the ultrasonic probe according to the embodiment of the present invention, and FIG. 1 (b) is an arrow view part IB in FIG. 1 (a). FIG. 2 is a cross-sectional view of the ultrasonic probe according to the embodiment of the present invention, FIG. 3A is a plan view of the transducer in the ultrasonic probe according to the embodiment of the present invention, 3 (b) is a view seen from the arrow IIIB in FIG. 3 (a), FIG. 3 (c) is a view seen from the arrow IIIC in FIG. 3 (a), and FIG. The figure which shows the state which immersed the to-be-inspected object in the water in a water tank, FIG.4 (b) is a figure along IVB-IVB in Fig.4 (a).

  As shown in FIG. 2, the ultrasonic probe 1 according to the embodiment of the present invention is used for inspecting the presence or absence of an internal defect of a round bar-shaped (radius R) billet W that is an inspection object having a curved surface. It is used. And the specific structure of the ultrasound probe 1 which concerns on embodiment of this invention is as follows. The billet W, which is an object to be inspected with a curved surface, is made of a Ti alloy.

  The ultrasonic probe 1 according to the embodiment of the present invention includes a case 3, and the case has an opening 5 on the distal end side. Further, an elliptical (longer diameter D1, shorter diameter D2) piezoelectric vibrator 7 for transmitting and receiving the ultrasonic wave S is provided on the opening 5 side in the case. The vibration surface of the piezoelectric vibration element 7 is as follows. A concave surface is formed so that the ultrasonic wave S can be focused. The piezoelectric vibrator 7 is made of a composite material.

  A connector 9 that can be connected to an ultrasonic flaw detector (not shown) via a cable (not shown) is provided on the base end surface of the case 3. The connector 9 is connected to the piezoelectric vibrator 7 with a pair of lead wires. 11 is electrically connected.

  A damper 13 that suppresses excessive vibration of the piezoelectric vibrator 7 is provided on the back side of the piezoelectric vibrator 7 in the case 3. A protective layer 15 that protects the piezoelectric vibrator 7 is provided at the tip of the case 3 so as to close the opening 5 of the case 3, and the protective layer 15 is made of synthetic resin. .

  Then, the principal part of the ultrasonic probe 1 which concerns on embodiment of this invention is demonstrated.

  As shown in FIGS. 1A, 1B, 3A, 3B, 4C, and 4A, 4B, the vibration surface (transmission / reception surface) of the piezoelectric vibrator 7 is inspected. It is formed by a set of propagation points k that are radiated from a common focal point f inside the object W and reach through the surface of the object W to reach the ultrasonic wave S with the same propagation time.

Specifically, the longitudinal center of the inspection object W is on the same plane as an arbitrary vertical cross section (AA ′ cross section) having an inclination angle φ (0 ° ≦ φ ≦ 180 °) with respect to the axial direction of the inspection object W. Arbitrary propagation point where the propagation time Tt of the ultrasonic wave S from the intersection point a between the line and the surface of the inspection object W is radiated from the common focal point f and reaches through the surface of the inspection object W is equal If the coordinates of k are (X, Y), X and Y can be expressed by the following relational expressions (1) and (2). The propagation time Tt of the ultrasonic wave S can be expressed by the following relational expression (3).

  Here, in relational expression (1), relational expression (2), and relational expression (3), Vm: speed of sound inside object W, P: water distance, Vw: speed of sound in water, | fb |: common From the focal point f to the intersection b of the path of the arbitrary emitted ultrasonic wave S and the surface of the object W to be inspected, α: the angle between the normal n at the intersection b and the arbitrary emitted ultrasonic wave S (Incident angle of an arbitrary emitted ultrasonic wave S), γ: an angle formed by a normal line n at the intersection point b and a perpendicular g passing through the intersection point b, and | fb | and (α + γ) are respectively inclined angles φ Is a function of Tm is the propagation time of the ultrasonic wave S inside the inspection object W, and Tw is the propagation time of the ultrasonic wave S in the water L. In FIG. 1, i is a tangent line at the intersection point b, and β is a refraction angle of the emitted ultrasonic wave S at the intersection point b.

  When the propagation points k having the same propagation time Tt of the ultrasonic wave S emitted from the common focus f and reaching the same are gathered while changing | fb | and (α + γ), a two-dimensional trajectory is formed. The Furthermore, when the propagation points k having the same propagation time Tt of the ultrasonic wave S emitted from the common focal point f and reaching the same are gathered while changing the tilt angle φ, the vibration surface of the piezoelectric vibrator 7 is formed.

  Subsequently, an ultrasonic flaw detection method according to an embodiment of the present invention will be described including its operation.

  That is, as shown in FIGS. 4A and 4B, the round bar-shaped inspection object W is set in a predetermined position in the water tank T while being immersed in the water L. Then, by using the ultrasonic probe 1 including the piezoelectric vibrator 7 configured as described above, the piezoelectric probe 7 is moved while moving the ultrasonic probe 1 along the axial direction of the inspection object W. Then, the ultrasonic wave S transmitted toward the axis of the inspection object W is made incident on the inspection object W, and the ultrasonic wave S as a reflected wave is received by the piezoelectric vibrator 7. Thereby, the presence or absence of a reflected wave (reflection echo) due to the internal defect of the inspection object W, in other words, the presence or absence of the internal defect of the inspection object W can be inspected along the axial direction of the inspection object W. In addition, the presence or absence of an internal defect of the inspection object W can be inspected in the circumferential direction of the inspection object W by rotating the inspection object W around the axis.

  As described above, the vibration surface of the piezoelectric vibrator 7 propagates with the same propagation time Tt of the ultrasonic wave S until it is radiated from a common focal point inside the inspection object W and reaches through the surface of the inspection object W. Since it is composed of a set of points, the focal lengths F of the ultrasonic waves S are equal in any vertical cross section having different inclination angles φ with respect to the axial direction of the inspection object W, in other words, transmitted from the piezoelectric vibrator 7. The ultrasonic wave S thus focused is focused on one point inside the inspection object W. As a result, even if the detection sensitivity of the ultrasonic wave S received by the piezoelectric vibrator 7 is not set high, the ultrasonic wave intensity of the reflected wave S due to the internal defect existing deep inside the inspection object W is sufficiently increased. Can be secured.

  Therefore, according to the embodiment of the present invention, it is possible to inspect the presence or absence of an internal defect in a deep portion inside the inspection object W with high accuracy while reducing noise echo.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, In addition, it can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

  Embodiments will be described with reference to FIGS. 5 (a) and 5 (b).

  Here, Fig.5 (a) is a figure which shows the ultrasonic waveform of invention, FIG.5 (b) is a figure which shows the ultrasonic waveform of a comparative product.

  First, the ultrasonic probe 1 (see FIG. 2) according to the embodiment of the present invention is prototyped as an inventive product, and a commercially available ultrasonic probe is prepared as a comparative product. Also, a simulated inspected object having a curved surface (curvature radius of 100 mm) and embedded artificial internal defects (depth of 75 mm) is prepared. Then, the waveform of the ultrasonic wave received as a reflected wave by the piezoelectric vibrator according to the invention (the ultrasonic wave waveform of the invention), the waveform of the ultrasonic wave received as a reflected wave by the piezoelectric vibrator in the comparative product (the comparative product) (Ultrasonic waveform) is as shown in FIGS. 5 (a) and 5 (b).

  That is, it was confirmed that the inventive product can inspect the presence or absence of the artificial internal defect at a deep location inside the simulated inspection object while reducing the noise echo compared to the comparative product. In addition, when the presence or absence of an artificial internal defect (depth 75 mm) was inspected, the SN ratio of the invention (ratio of defect echo intensity to noise echo intensity) was 7.0, and the SN ratio of the comparative product was 1 .6. Furthermore, although the illustration of the ultrasonic waveform is omitted, when the presence or absence of an artificial internal defect (depth 100 mm) is inspected, the SN ratio of the invention product is 4.0 and the SN ratio of the comparison product is 1.0. is there.

FIG. 1A is a diagram for explaining a vibration surface of a transducer in an ultrasonic probe according to an embodiment of the present invention, and FIG. 1B is an enlarged view of an arrow IB in FIG. It is. It is sectional drawing of the ultrasonic probe which concerns on embodiment of this invention. 3A is a plan view of the transducer in the ultrasonic probe according to the embodiment of the present invention, FIG. 3B is a diagram viewed from the arrow IIIB in FIG. 3A, FIG. (C) is the figure seen from the arrow IIIC in FIG. 3 (a). FIG. 4A is a diagram showing a state in which the inspection object is immersed in water in the water tank, and FIG. 4B is a diagram along IVB-IVB in FIG. FIG. 5A is a diagram showing the ultrasonic waveform of the invention, and FIG. 5B is a diagram showing the ultrasonic waveform of the comparative product. It is a figure explaining the conventional ultrasonic probe. It is a figure explaining the subject of the conventional ultrasonic probe.

Explanation of symbols

S Ultrasonic wave W Inspected object (billet)
DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 3 Case 5 Opening 7 Piezoelectric vibrator 9 Connector 11 Lead wire 13 Damper 15 Protective layer

Claims (3)

In an ultrasonic probe used for inspecting the presence or absence of an internal defect of an object whose surface is curved,
A probe case,
A transducer provided in the probe case, for transmitting and receiving ultrasonic waves,
The vibration surface of the vibrator is constituted by a set of propagation points that are radiated from a common focal point inside the inspection object and reach the ultrasonic wave through the surface of the inspection object. An ultrasonic probe characterized by that. Using an ultrasonic probe equipped with a transducer for transmitting and receiving ultrasonic waves, the ultrasonic wave transmitted from the transducer is made incident on an inspected object having a curved surface, and the ultrasonic wave is reflected as a reflected wave by the transducer. In the ultrasonic flaw detection method for inspecting the presence or absence of an internal defect of the inspection object by receiving
The vibration surface of the vibrator is composed of a set of propagation points that are radiated from a common focal point inside the inspection object and reach the ultrasonic wave through the surface of the inspection object. An ultrasonic flaw detection method characterized by the above.   The ultrasonic inspection method according to claim 2, wherein the inspection object has a round bar shape.

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