JP2007114075A - Ultrasonic probe for ultrasonic flaw detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic probe capable of converging ultrasonic waves, even to a deep location of an inspection object having surface that is a concave face. <P>SOLUTION: An acoustic lens 103, having a curvature radius of 1/2 to 2/3 of curvature radius of the concave face of the inspection object 102, is interposed between an ultrasonic wave generating or/and receiving element 105 and the inspection object 102, the convergence effect of the ultrasonic waves due to the concave face of the inspection object 102 is reduced by the refraction in the diffusion direction of the ultrasonic waves, when the ultrasonic waves propagate from the acoustic lens 103 to an intermediate medium (contact medium), and the ultrasonic waves are thereby converged, from the concave face to a deep part (about several times of the curvature radius of the concave face) and receive echoes of the ultrasonic waves from a defect 106 located in its deep part, by a reverse propagation route. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe of an ultrasonic flaw detector, and more particularly to an ultrasonic flaw detection technique in the case where a metal is an inspection object and the inspection surface of the inspection object is a concave curved surface.

  As a solid nondestructive inspection method that allows propagation of both longitudinal and transverse waves such as metal, an ultrasonic method (ultrasonic flaw detection method) has been generally used. Among these, the following inspection methods are conventionally known as methods for inspecting curved surfaces.

  For example, according to Non-Patent Document 1, which is one of JIS standards relating to ultrasonic flaw detection, “the probe shall be used with a shoe fitted to the shape of the flaw detection surface”. When the surface to be inspected is a curved surface, a method using an acoustic wedge material called a shoe is generally used.

  Further, in the case of a curved surface having a large curvature radius on the surface to be inspected, according to Non-Patent Document 2, “the length of the flaw detection surface is 50 mm or more and less than 1500 mm and the wall thickness to outer diameter ratio is 16% or less. Regarding the ultrasonic inspection test method for welded parts of joints, it says that “the curved surface of the contact surface of the probe is not processed.” With regard to the influence of curvature, there is a method to correct for changes in refraction angle and sensitivity. Are listed.

  The above-described method is a description relating to an oblique flaw detection method using a sound wave propagating in an oblique direction. In addition, there is a nondestructive inspection method using ultrasonic waves called TOFD method. The TOFD method is a widely used technique for measuring the depth of the end of the crack to be inspected. According to Patent Document 1 “Ultrasonic TOFD probe and flaw detection method”, When the surface is a curved surface, there is a description that “the contact surface of the probe holder that contacts the curved surface portion of the subject is formed in a shape along the curved surface portion of the subject”. The radius of curvature and the radius of curvature of the contact surface of the probe are the same value.

  As described above, in the conventional ultrasonic inspection apparatus, the curved surface shape of the surface to be inspected is matched as much as possible with the curved surface of the contact surface of the ultrasonic probe, and the method of placing importance on the contact property of the curved surface and the curvature is large. In some cases, the contact surface of the probe remains flat, and a contact medium called water (machine water, machine oil, glycerin, etc.) is filled between the probe and the object to be inspected. A technique for improving propagation efficiency has been common.

JP 2004-53462 A JIS G 0587 “Ultrasonic flaw detection method for carbon steel and low alloy steel forgings” Annex 2 “Ultrasonic flaw detection method for forging steel products by oblique angle method” Appendix 4 of JIS Z 3060 "Ultrasonic flaw detection test method for steel welds" "Flaw detection method for welds of long joints"

  The above-described method is effective when the surface of the metal to be inspected is a concave surface (or convex surface) with a gentle curvature or when the inspection region is relatively limited to the vicinity of the surface. However, when the surface is a concave surface with a small radius of curvature and the region to be inspected is deep (for example, about 1 to several times as large as the radius of curvature), the ultrasonic wave is deepened while maintaining sufficient strength. Could not be propagated.

  When the object to be inspected is a material with relatively high speed of sound and high density, such as metal, when the ultrasonic wave is incident on the concave surface, the concave shape acts as an acoustic lens, and the ultrasonic wave exceeds the depth of the ultrasonic wave. There is a region where the strength is weakened, that is, a flaw detection limit region. For this reason, it has been difficult to perform ultrasonic flaw detection in a deep part of a metal having a concave surface.

  An example will be described with reference to FIGS. FIG. 3 shows the result of analyzing the propagation of ultrasonic waves when the ultrasonic probe 302 that generates a vertical beam is brought close to the inspection object 304 whose surface is concave (the radius of curvature is 20 mm) and the flaw is analyzed. It is the figure shown by (sound ray). It is assumed that the space between the ultrasonic probe 302 and the inspection object 304 is filled with water as the intermediate medium 303.

From the result of FIG. 3, it can be seen that the ultrasonic wave transmitted straight from the ultrasonic probe 302 is refracted by the concave shape of the inspection object 304 and the ultrasonic wave is focused in the region 305 in the inspection object 304. In this case, the flaw detection limit region 301 is about 0.3 times the radius of curvature of the concave shape of the inspection object 304. The longitudinal wave sound velocity of the inspection object 304 was 5900 m / second, and the longitudinal wave sound velocity of water was 1500 m / second.

  Next, this situation is somewhat improved in the case shown in FIG. The difference between FIG. 3 and FIG. 4 is that an acoustic lens (also referred to as a shoe) made of a synthetic resin is used as an intermediate medium between the ultrasonic probe 302 and the inspection object 304. Here, the longitudinal wave sound velocity of the synthetic resin was set to 2700 m / sec. It is assumed that the acoustic lens 402 is in close contact with the curvature of the inspection object 304.

  In the case of FIG. 4, since the difference between the sound speed of the object to be inspected (metal) and the sound speed of the intermediate medium (synthetic resin) is smaller than the difference between the sound speed of metal and water, the refraction on the surface of the object to be inspected becomes gradual. It can be seen that the ultrasonic waves are focused on the region 403, and the flaw detection limit region 401 is about 2 to 3 times deeper than the case where the intermediate medium is water.

  The range of the limit region depends on the radius of curvature of the surface to be inspected and the sound velocity ratio of the object to be inspected (metal) and the intermediate medium. The radius of curvature of the surface of the metal to be inspected is R and the sound velocity of the longitudinal wave of the metal is V2. When the sound speed of the intermediate medium is V1, the depth of the flaw detection limit distance can be approximately evaluated as R × γ / 1−γ using the sound speed ratio γ = V1 / V2. When γ (water / metal) = 1500/5900 = 0.254, for the concave curvature radius R, 0.34 × R is the flaw detection limit depth. Further, when γ (synthetic resin / metal) = 2700/5900 = 0.458, the depth of the flaw detection limit distance is 0.84 × R, which is in good agreement with the tendency of the analysis results in FIGS.

  As described above, since the curvatures of the contact surfaces of the inspection object 304 and the acoustic lens 402 of the ultrasonic probe are matched, ultrasonic flaw detection is performed in a deep region exceeding the flaw detection limit distance determined depending on the sound speed ratio between the two. There was a problem that it was difficult.

  Furthermore, if the contact surface of the ultrasonic probe is set to a value substantially equal to the radius of curvature of the surface of the inspection object 304, there are many variations in the shape of the inspection object due to machining or welding, In such a case, there is a problem in that the adhesion with the inspection object cannot be maintained, and the incidence efficiency of ultrasonic waves on the inspection object decreases.

  Therefore, the problem to be solved by the present invention is a concave curved surface to be inspected, and even if the inspection region to be inspected is a region deeper than the radius of curvature of the concave curved surface, the ultrasonic wave is concentrated on the inspection region. It is an object to provide an ultrasonic probe that can be propagated.

  The basic configuration of the present invention includes an element that transmits ultrasonic waves, an acoustic lens that propagates the ultrasonic waves to the concave curved surface portion to be inspected, and an echo of the ultrasonic waves from the inspection object via the acoustic lens. In the ultrasonic probe of an ultrasonic flaw detector provided with a receiving element, the surface of the acoustic lens facing the concave curved surface portion has a shape of a convex curved surface having a curvature radius smaller than the curvature radius of the concave curved surface portion. And the acoustic lens is made of ultrasonic waves in an intermediate medium between the ultrasonic probe and the inspection object, and the longitudinal wave sound speed of the ultrasonic wave is slower than the longitudinal wave sound speed in the inspection object. This is an ultrasonic probe of an ultrasonic flaw detector characterized by being made of a material faster than the longitudinal wave sound velocity.

  Such an ultrasonic probe is used by being connected to an ultrasonic flaw detector. When an electric signal is applied from an ultrasonic flaw detector to an element that transmits ultrasonic waves, the element that transmits ultrasonic waves transmits an electric signal. Converted into sonic vibration, ultrasonic waves are transmitted into the acoustic lens, the ultrasonic waves are refracted when propagating from the acoustic lens to the intermediate medium, and the ultrasonic waves propagate in the intermediate medium in the diffusion direction. When an ultrasonic wave enters the inspection object, the ultrasonic wave is refracted and propagates through the inspection object in the focusing direction. In this manner, since the ultrasonic wave is once diffused immediately before the ultrasonic wave propagates to the inspection object, the ultrasonic wave is focused at a deeper position of the inspection object than when the ultrasonic wave does not go through the diffusion process. When there is an ultrasonic reflection source in the region where the ultrasonic waves are focused, the ultrasonic wave is reflected by the reflection source and returned to the means for receiving the ultrasonic echo as an echo, and is received as an electrical signal. It is converted and input to the ultrasonic flaw detector, and inspection results such as the presence or absence of a reflection source are obtained with the ultrasonic flaw detector.

The following requirements may be added to such a basic configuration. That is,
(1) One to two thirds of the curvature radius of the concave curved surface to be inspected by the ultrasonic lens and the ultrasonic wave generation and reception elements adopted as the means for transmitting and receiving the ultrasonic wave A convex acoustic lens having a radius of curvature in the range.
(2) An ultrasonic wave generation and reception element employed as a means for transmitting and receiving ultrasonic waves is composed of a vibrator array composed of a plurality of vibrators arranged in at least one direction. Have at least one array sensor.
(3) A shielding plate that acoustically blocks an acoustic propagation region between the transmitted ultrasonic wave and the received echo is provided inside the acoustic lens.
(4) A medium having a longitudinal wave velocity of 2400 m / sec to 2900 m / sec is used as the acoustic lens.

  Another basic configuration of the present invention includes an element for transmitting an ultrasonic wave, an acoustic lens for propagating the ultrasonic wave to a concave curved surface part to be inspected, and an echo of the ultrasonic wave from the inspection object via the acoustic lens. In the ultrasonic probe of the ultrasonic flaw detector, the surface of the acoustic lens facing the concave curved surface portion has the shape of a convex curved surface, the same as the protruding direction of the convex curved surface. An ultrasonic probe of an ultrasonic flaw detector in which an element for transmitting the ultrasonic wave with a curvature protruding in a direction and an element for receiving the echo are arranged.

  Even in such an ultrasonic probe, when an electrical signal is applied from an ultrasonic flaw detector to an element that transmits ultrasonic waves, the element that transmits ultrasonic waves is used. The electrical signal is converted into ultrasonic vibration, and the ultrasonic wave is transmitted into the acoustic lens in the diffusion direction. The ultrasonic wave propagates in the acoustic lens in the diffusion direction, and then propagates in the focusing direction when propagating through the inspection object. Therefore, compared with the case where the ultrasonic wave does not go through the diffusion process, the ultrasonic wave is focused at a deeper position of the inspection object. When there is an ultrasonic reflection source in the region where the ultrasonic waves are focused, the ultrasonic wave is reflected by the reflection source and returned to the means for receiving the ultrasonic echo as an echo, and is received as an electrical signal. It is converted and input to the ultrasonic flaw detector, and inspection results such as the presence or absence of a reflection source are obtained with the ultrasonic flaw detector.

The requirement described below may be added to such other basic configuration. That is,
(5) A convex acoustic lens having a radius of curvature along the radius of curvature of the concave curved surface to be inspected, and a convex ultrasonic wave having a radius of curvature larger than three times the radius of curvature of the concave curved surface to be inspected Provide generating and / or receiving elements.
(6) The ultrasonic probe according to (5) includes a transducer array composed of a plurality of transducers arranged in at least one direction as an element for generating and / or receiving ultrasound. Can have an array sensor.
(7) The ultrasonic probe according to (6) may be characterized in that the cross-sectional shape of a plurality of transducers constituting the array sensor is a trapezoid.

  As described above, according to the present invention, even when the surface to be inspected is a concave curved surface and the region to be inspected is deep (for example, about 1 to several times the radius of curvature), ultrasonic waves Can be propagated so as to be focused in a deep region, and ultrasonic flaw detection can be performed in a deep portion of a concave curved surface.

  In the embodiment of the present invention, in the case of inspecting the presence or absence of scratches to be inspected using a concave metal material, the acoustic lens material (medium) has a longitudinal wave sound velocity of about 2400 m / sec to 2900 m / sec. It is made of a synthetic resin such as acrylic, polystyrene, polyimide, etc., and the metal to be inspected has a longitudinal wave sound velocity of about 5900 m / second, and a middle wave whose longitudinal wave sound velocity of water or glycerin is about 1500 m / second. In the following, it is assumed that ultrasonic flaw detection is performed through a medium.

  The ultrasonic probe is used by being connected to an ultrasonic flaw detector. When an electric signal is applied from the ultrasonic flaw detector to a means for transmitting ultrasonic waves, an element for transmitting ultrasonic waves and a concave curved surface portion to be inspected are used. In the ultrasonic probe of an ultrasonic flaw detector, comprising: an acoustic lens for propagating the ultrasonic wave to the element; and an element for receiving the ultrasonic echo from the inspection object via the acoustic lens. The surface of the acoustic lens that faces the curved surface portion has a convex curved surface shape with a radius of curvature smaller than the radius of curvature of the concave curved surface portion, and the acoustic lens is made of ultrasonic longitudinal wave sound velocity as the inspection object. It is made of a material that is slower than the longitudinal longitudinal sound velocity and faster than the longitudinal acoustic velocity of the ultrasonic wave in the intermediate medium between the ultrasonic probe and the inspection object.

  When an element that transmits ultrasonic waves receives an electrical signal from an ultrasonic flaw detector, the element converts the electrical signal into ultrasonic vibrations, and the ultrasonic waves are transmitted into the acoustic lens. Propagates in the diffusion direction, and then propagates in the focusing direction when ultrasonic waves propagate from the intermediate medium into the object to be examined. Therefore, since the ultrasonic wave is once diffused immediately before the ultrasonic wave propagates to the inspection object, the ultrasonic wave is focused at a deeper position of the inspection object as compared with the case where the ultrasonic wave does not go through the diffusion process once. When there is an ultrasonic reflection source in the region where the ultrasonic waves are focused, the ultrasonic wave is reflected by the reflection source and returned to the means for receiving the ultrasonic echo as an echo, and is received. The echo received by the means is converted into an electrical signal and input to the ultrasonic flaw detector, and the received waveform including the waveform reflected by the reflection source is displayed on the display device of the ultrasonic flaw detector, and the presence or absence of the reflection source is inspected. Can be judged.

  As described above, the embodiment of the present invention can provide an ultrasonic probe capable of setting the ultrasonic focusing position to a deep position to be inspected.

By adding the above-described requirements (1) to (4) to such a basic configuration, the following characteristic operational effects are added for each added requirement. That is,
According to the ultrasonic probe adopting the requirement (1) described above, the ultrasonic wave transmitted from the ultrasonic wave generating element propagates through the acoustic lens before propagating into the metal. As the acoustic lens medium, the longitudinal wave sound velocity is normally set to be faster than water (1500 m / sec) and slower than metal (5900 m / sec), so that a material is used. For example, as described in the requirement (4), the longitudinal wave sound velocity propagating through the acoustic lens is a medium having a speed of about 2400 m / sec to 2900 m / sec, such as a synthetic resin such as acrylic, polystyrene, polyimide, or the like. An acoustic lens can be used.

  The ultrasonic wave propagating in the acoustic lens propagates from the acoustic lens to the intermediate medium, that is, when the ultrasonic wave enters the slow medium from the medium with a high speed of sound, due to the refraction phenomenon due to the convex shape of the surface of the convex acoustic lens. The direction changes to the diffusion direction.

  Furthermore, when ultrasonic waves are incident on the metal material to be inspected from the intermediate medium, that is, from the medium having a low sound speed to the medium having a high speed, the ultrasonic wave travels in the direction of the ultrasonic wave due to the refraction phenomenon of the sound wave due to the convex shape of the metal surface. It changes in the focusing direction.

  At this time, in general, the focusing effect by the metal surface has a stronger influence on the diffusion effect by the acoustic lens and the focusing effect by the metal surface. In the ultrasonic probe adopting the requirement (1), the radius of curvature of the acoustic lens is set to a value smaller than the radius of curvature of the metal surface (1/2 to 2/3 of the radius of curvature of the metal surface). As a result, a stronger diffusing effect can be obtained as compared with a conventional close-contact acoustic lens, and the strong diffusing effect on the metal surface can be mitigated. In addition, since the radius of curvature is set smaller than that of the metal surface, the probe can be pressed against the curved surface even when the radius of curvature of the metal surface varies from several millimeters to 10 millimeters. The entrance / exit efficiency with respect to the ultrasonic inspection object is improved.

  The focusing effect by the acoustic lens will be described with reference to FIG. In FIG. 21, as already described, in the case of an intermediate medium having the same curvature radius as the curvature to be inspected (radius of 20 mm) (same as in FIG. 4), the curvature radius is slightly small (set to a radius of 15 mm). As with FIGS. 3 and 4, the propagation of ultrasonic waves was shown by analysis. By making the curvature radius of the acoustic lens smaller than the curvature radius of the metal surface, the ultrasonic wave transmitted from the acoustic lens to the water once diffuses and then converges when incident on the metal. When the radius of curvature of the acoustic lens is equal to the radius of curvature of the metal surface (401 in the upper diagram of FIG. 21), it can be confirmed that the ultrasonic wave has reached a position 2101 deeper.

  Further, according to the ultrasonic probe adopting the requirement (2) described above, when there is a variation in the metal surface, the optimum focusing corresponding to the radius of curvature of the metal surface is made by utilizing the characteristics of the array sensor. Ultrasound can be formed.

  Here, the array sensor is a sensor for generating and receiving ultrasonic waves used in a phased array type ultrasonic flaw detection method. The phased array method is also called an electronic scanning method or an electronic scanning method. For example, an ultrasonic probe (array sensor or array probe) in which a plurality of ultrasonic generating elements made of piezoelectric elements are arranged in an array. Is applied to each element of the array sensor with a predetermined time delay, and the ultrasonic waves generated from each element are superimposed to form a composite wave. Conditions such as the transmission angle and reception angle of ultrasonic waves to the inspection object, the transmission position and reception position, or the position where the combined wave interferes and strengthens each other, that is, the focal position, are changed at high speed by electrical control. It is an ultrasonic flaw detection method that can be used. Here, the timing of ultrasonic wave generation and / or reception given to each element is hereinafter referred to as a delay time pattern.

  By using the array sensor in this way, when the curvature radius of the inspection object varies, as described in (1), the contact property obtained by making the curvature radius of the acoustic lens smaller than the curvature radius of the metal surface can be obtained. In addition, by electronically changing the delay time pattern applied to each element that constitutes the array sensor, the divergence effect can be controlled in accordance with the radius of curvature of the inspection object having a variation, which is influenced by the variation. Accordingly, it is possible to transmit a divergent ultrasonic beam in which the strong focusing effect by the metal surface is canceled.

  Moreover, according to the probe which employ | adopted the requirement of (3), the noise which generate | occur | produces when an ultrasonic wave carries out multiple reflection within an acoustic lens can be suppressed.

  Since the ultrasonic generator and acoustic lens are in contact with each other, reflection from the boundary layer between the acoustic lens and the intermediate medium causes multiple reflections of ultrasonic waves to remain in the acoustic lens as reverberation, resulting in a strong noise signal. There is concern about sex. In order to avoid this noise, in addition to physically separating the element for generating ultrasonic waves and the element for receiving ultrasonic waves, a sound insulating plate (the material is, for example, cork or rubber sound insulating) ), It is possible to avoid the multiple reflection noise in the acoustic lens from being mixed into the receiving element.

  In an ultrasonic probe according to another embodiment of the present invention, an element that transmits ultrasonic waves, an acoustic lens that propagates the ultrasonic waves to the concave curved surface portion of the inspection object, and an echo of the ultrasonic waves from the inspection object In the ultrasonic probe of the ultrasonic flaw detector, wherein the surface of the acoustic lens facing the concave curved surface portion has a convex curved surface shape. An element that transmits the ultrasonic wave with a curvature protruding in the same direction as the protruding direction of the curved surface and an element that receives the echo are disposed.

  Even in such an ultrasonic probe, when an electrical signal is applied from an ultrasonic flaw detector to an element that transmits ultrasonic waves, the element that transmits ultrasonic waves is used. The electrical signal is converted into ultrasonic vibration, and the ultrasonic wave is transmitted into the acoustic lens in the diffusion direction. The ultrasonic wave propagates in the acoustic lens in the diffusion direction, and then propagates in the focusing direction when propagating through the inspection object. Therefore, compared with the case where the ultrasonic wave does not go through the diffusion process, the ultrasonic wave is focused at a deeper position of the inspection object. When there is an ultrasonic reflection source in the region where the ultrasonic waves are focused, the ultrasonic wave is reflected by the reflection source and returned to the means for receiving the ultrasonic echo as an echo, and is received as an electrical signal. It is converted and input to the ultrasonic flaw detector, and inspection results such as the presence or absence of a reflection source are obtained with the ultrasonic flaw detector. Here, as a medium of the acoustic lens, a material whose longitudinal wave sound speed is set to be faster than that of water (1500 m / sec) and slower than that of a metal to be inspected (5900 m / sec) is used.

  It is also possible to add the above requirements (5), (6) and (7) to such other basic configurations.

  The ultrasonic wave propagating in the acoustic lens propagates from the acoustic lens to the intermediate medium, that is, when the ultrasonic wave enters the slow medium from the medium with a high speed of sound, due to the refraction phenomenon due to the convex shape of the surface of the convex acoustic lens. The direction changes to the diffusion direction.

  Furthermore, when ultrasonic waves are incident on the metal material to be inspected from the intermediate medium, that is, from the medium having a low sound speed to the medium having a high speed, the ultrasonic wave travels in the direction of the ultrasonic wave due to the refraction phenomenon of the sound wave due to the convex shape of the metal surface. It changes in the focusing direction.

  At this time, in general, the focusing effect by the metal surface has a stronger influence on the diffusion effect by the acoustic lens and the focusing effect by the metal surface. In the ultrasonic probe to which the requirement (5) is added, the curvature radius of the acoustic lens is set to a value equivalent to the curvature radius of the metal surface, and a sufficient diffusion effect cannot be obtained. Therefore, by providing a convex curvature (a radius of curvature larger than three times the radius of curvature of the metal surface to be inspected) to the element that generates or / and receives ultrasonic waves, the state of adhesion to the metal surface is maintained. Further, a stronger diffusion effect of ultrasonic waves can be obtained, and a strong focusing effect on the metal surface can be mitigated.

  Moreover, according to the ultrasonic probe to which the requirement (6) described above is added, by determining the shape according to the minimum value of the concave curvature radii of the metal surface assumed within the range of variation. When there is a variation in the metal surface, the optimum focused ultrasonic wave corresponding to the radius of curvature of the metal surface to be inspected can be formed by utilizing the characteristics of the array sensor.

  Further, according to the ultrasonic probe to which the requirement (7) described above is added, when the array sensor is formed on a curved surface such as in an acoustic lens, the cross-sectional shape of the element is changed to a trapezoidal shape. The shape following property of the element is improved.

  The improvement in shape followability is very effective in the following cases, for example. When there are many kinds of curvature radii of the curved surface to be inspected, multiple acoustic lenses with different curvature radii are prepared, and the array sensor is used in close contact with the acoustic lens, thereby supporting various curvature radii. It can be used as an ultrasonic probe for curved surfaces. At this time, since the array sensor repeats adhesion and peeling to surfaces having different curvatures, a cut is provided on the surface of the element constituting the array sensor (the side that does not contact the concave surface) to provide followability to a curved surface. An improved and highly reliable ultrasonic probe can be configured.

  Hereinafter, an ultrasonic flaw detection method and apparatus according to the present invention will be described in detail with reference to embodiments shown in the drawings. In addition, assuming that the inspection object is a metal, the inspection surface of the metal is a concave curved surface with a radius of curvature of several tens to one hundred millimeters, and the inspection of the base material and welded part with a thickness of several tens to one hundred millimeters is assumed. Yes.

  FIG. 1 shows a first embodiment of the present invention. As shown in the figure, an ultrasonic probe 101 to which an ultrasonic wave is incident is pressed against an inspection object 102 that is the object of the inspection to detect flaws. The defect to be inspected is, for example, an inherent defect such as a crack 104 opened on the curved surface side or a defect 106. The element 105 in the ultrasonic probe 101 includes a transmitting element that generates an ultrasonic wave by an applied electric signal and a receiving element that generates an electric signal by receiving an ultrasonic wave (both elements are equivalent to 105). And an acoustic lens 103. The transmitting element and the receiving element may be used as a single element, and may be controlled by an ultrasonic flaw detector so as to switch between the generation of ultrasonic waves and the reception of ultrasonic echoes. The touch element is equipped with one element that is used for both transmission and reception.

The application destination of the embodiment is ultrasonic inspection of a metal (for example, stainless steel) having a concave curved surface and a welded portion thereof, and the curved surface of the inspection object 102 is locally a part of a cylindrical surface or a spherical surface. It can be considered that it is formed from parts. Further, FIG. 1 shows the crack 104 that opens to the curved surface side, but the present invention can be similarly applied to a crack that does not necessarily open to the curved surface portion.

  It is assumed that a contact medium such as water or glycerin (or also called coplant) is applied or filled between the inspection object 102 and the ultrasonic probe as an intermediate medium in order to improve acoustic propagation. .

  An acoustic lens 103 having an intermediate characteristic between the inspection object 102 and the contact medium is used. For example, a synthetic resin such as acrylic, polystyrene, or polyimide is used. These materials have a longitudinal wave propagation speed of 2400 m / sec to 2900 m / sec, which is an intermediate sound speed between the inspection object 102 and the contact medium.

The optimum value of the radius of curvature of the acoustic lens depends on the radius of curvature of the inspection object 102 and the sound wave ratio of the longitudinal wave sound velocity of the medium of the acoustic lens, the longitudinal wave sound velocity of the intermediate medium, and the longitudinal wave sound velocity of the inspection object 102. For example, when the sound speed of the acoustic lens is 2700 m / second, the sound speed of the intermediate medium is 1500 m / second, and the sound speed of the inspection object 102 is 5900 m / second, the optimal curvature radius of the acoustic lens with respect to the curvature radius R is
It can be approximately evaluated as 0.6 × R. Here, the ratio between the curvature radius R of the surface to be inspected and the optimal curvature radius of the acoustic lens is referred to as an optimum value factor.

  Here, “optimum” means that the focusing effect due to the concave surface of the inspection object 102 satisfies the condition that the divergence effect due to the convex surface of the acoustic lens cancels out, and the radius of curvature of the acoustic lens is larger than the optimal value. In this case, since the diffusion effect by the acoustic lens is weakened, the focusing effect on the surface of the inspection object 102 is overcome, and a phenomenon in which a focal point is formed at a position shallower than a desired depth occurs.

  On the contrary, when the radius of curvature of the acoustic lens is smaller than the optimum value, the diffusion effect by the acoustic lens is superior to the focusing effect by the surface of the inspection object 102, so that a divergent sound field is formed inside the inspection object 102. It will be.

  FIG. 2 is a graph showing the analysis results when the acoustic velocity of the acoustic lens is on the horizontal axis, the optimum value factor is on the vertical axis, and the acoustic velocity of the metal to be inspected is 5500 m / sec and 6000 m / sec. When the sound speed of the acoustic lens is between 2400 m / sec and 2900 m / sec, the curvature radius of the surface to be inspected with respect to a typical longitudinal wave sound velocity value (5500 to 6000 m / sec) of a metal material such as stainless steel. The optimal value factor for the ratio of R and the optimal radius of curvature of the acoustic lens is in the range of 1/2 to 2/3, and when the radius of curvature of the acoustic lens is in the vicinity of the above value, Thus, it can be confirmed that the focusing effect on the surface to be inspected and the diffusion effect by the acoustic lens cancel each other, and that the ultrasonic wave is efficiently incident to the deep part of the object to be inspected.

  Such a thing can be obtained even if a normal piezoelectric element is used as the ultrasonic wave generation / reception element 105, and the ultrasonic wave can be focused to a deep part. However, in order to improve the S / N ratio by reducing the multiple reflection echoes in the acoustic lens and to follow the change in the radius of curvature of the inspection object, the ultrasonic wave generation / reception element 105 constituting the ultrasonic probe is used. As an example, an array sensor as shown in FIGS. 5A and 5B may be used.

In the ultrasonic probe 501 having an array sensor, a plurality of elements 502 constituting the array sensor are arranged one-dimensionally or two-dimensionally.

  The features of the array sensor will be described with reference to FIG. The array sensor is composed of small pieces of piezoelectric elements that can transmit and receive ultrasonic waves, and by giving a delay time to the timing of generating ultrasonic waves in each element by control from an ultrasonic flaw detector, By changing the state of interference of the generated ultrasonic waves, various sound fields such as focusing, paralleling, and divergence can be formed.

  FIG. 6A shows an example of a delay time pattern and a sound field with respect to a diverging sound field (a cross-sectional view including a normal direction of a sensor surface of a one-dimensional array sensor of 2 MHz, 1 mm × 24 elements), and FIG. ) Is a flat, and FIG. 6C shows a calculation example of divergence. It can be seen that the sound field changes from focusing to divergence by changing the pattern of the timing (delay time) of ultrasonic generation from the element.

  For example, when the element 502 is arranged one-dimensionally, the following two combinations are conceivable depending on the relationship with the direction of the acoustic lens. In the combination 1, the element arrangement direction of the elements constituting the array sensor and the axial direction of the acoustic lens 103 are parallel as shown in FIG. 26A, and in the combination 2, the element arrangement direction of the elements constituting the array sensor and the acoustic lens 103 This is a case where the axial directions are orthogonal as shown in FIG. 26B.

  In the case of the combination 1, since the arrangement direction of the elements constituting the array sensor is the axial direction of the acoustic lens, the sound field by the array sensor is not related to the delay time pattern given to each element. It will be affected only by the radius of curvature.

  For this reason, only one element is represented on the cross-sectional view (FIG. 5A) perpendicular to the axial direction of the acoustic lens. For this reason, in the case of explaining the effect of the acoustic lens, in the case of the pattern 1, it can be regarded as the same as the explanation in the case where the ultrasonic probe 101 does not have an array structure. The description (FIGS. 1, 2 and 21A) of (sensors not having an array structure) and the description of the “combination 1” array sensor can be regarded as common.

  On the other hand, in the case of the combination 2, since the curvature of the acoustic lens is attached in the direction of the element arrangement of the array sensor, the sound field by the array sensor changes depending on the delay time pattern given to each element.

  A specific array sensor structure (arrangement of elements and acoustic lenses) will be described with reference to FIGS. 7 and 8 correspond to the case of the above-described “combination 2” array sensor, in which the axial direction of the acoustic lens and the arrangement direction of the elements are orthogonal to each other.

  In FIG. 7, the array sensor group 701 and the array sensor group 702 are arranged on the left and right with the sound insulation plate 703 interposed therebetween. FIG. 8 shows the array sensor group 801 and the array sensor group 802 with the sound insulation plate 803 interposed therebetween. Is arranged vertically. These types of array sensors are suitable, for example, for inspecting a defect 704 that enters the inspection object 102 in the horizontal direction.

  On the other hand, the array sensor shown in FIGS. 9 and 10 corresponds to the above-described “combination 1” array sensor, and is the case where the axial direction of the acoustic lens and the direction of the element arrangement are parallel. In FIG. 9, the array sensor group 901 and the array sensor group 902 are arranged on the left and right with the sound insulation plate 903 interposed therebetween, and FIG. 10 shows the array sensor group 1001 and the array sensor group 1002 with the sound insulation plate 1003 interposed therebetween. Is arranged vertically. These types of sensors are suitable, for example, for inspecting a defect 904 entering the vertical direction with respect to the inspection object 102.

  When there is a change in the radius of curvature of the inspection object, in the case of the array sensor shown in FIGS. 7 and 8, since the elements are arranged on the curvature side of the acoustic lens, the delay as shown in FIG. By controlling the time, it is possible to electronically control the degree of convergence or divergence of the ultrasonic wave transmitted to the inside of the inspection object, so that it is easy to follow the curvature radius of the inspection object.

  However, in the array sensor shown in FIGS. 9 and 10, since the elements are not arranged on the side where the curvature of the acoustic lens is present, it becomes difficult to cope with the curvature change of the inspection target surface.

  Therefore, an improvement plan of the array sensor shown in FIGS. 9 and 10 is shown in FIGS. The array sensor group 901 and the array sensor group 902 in FIG. 9 are further divided into three columns to form an array sensor group 1101 and an array sensor group 1102 (FIG. 11). Similarly, the array sensor group 1001 and the array sensor group 1002 shown in FIG. 10 are also divided into three columns to form an array sensor group 1201 and an array sensor group 1202 (FIG. 12). Since the elements constituting the array sensor are arranged two-dimensionally, the elements are arranged even on the side where the curvature of the acoustic lens is provided, so that the inspection object is controlled by electronic control of the delay time. It is possible to form an optimum focused or diverging sound field corresponding to a change in the radius of curvature of

  In any array sensor, one group of two array sensor groups is used for ultrasonic wave generation (also referred to as transmission) and the other group is used for ultrasonic wave reception. When there is only one array sensor group, a plurality of selected elements in the group may be used for reception in addition to a plurality of elements selected for ultrasonic generation.

  The internal structure of the ultrasonic probe 501 having an array sensor will be briefly described with reference to FIGS. 19 and 20. 19 and 20 correspond to FIGS. 7 and 8 described above, but only the arrangement of the acoustic lens and the sound insulating plate is different, and the same internal structure is used in FIGS. 9 and 10.

  The array sensor 501 includes an element 502 for transmission / reception, a backing layer 1902 for appropriately limiting the vibration time of the element, a matching layer 1903 for adjusting transmission / reception efficiency, and the acoustic lens 103. The other parts are housed in a case 1901 except that the acoustic lens 103 is exposed to the outside. These parts are integrally coupled by bonding or screws.

  When separate array sensor groups are used for transmission of ultrasonic waves and reception of echoes, in FIG. 7 to FIG. 12, the acoustic lens is provided with a sound insulating plate for preventing acoustic propagation (described later). In order to prevent acoustic crosstalk between the transmitting and receiving array sensor groups, a sound insulating plate 2001 may be provided inside the array sensor as shown in FIG.

Next, the focusing effect by the acoustic lens will be described with reference to FIGS. 21A to 21C. FIG. 21A is an explanatory diagram of a case where the ultrasonic probe 101 is a conventional sensor (a sensor not having an array structure) and an array sensor of “combination 1”. FIG. 21B and FIG.
It is explanatory drawing in the case of the array sensor of "combination 2".

  In FIG. 21A, as already described, in the case of an intermediate medium having the same curvature radius as the curvature to be inspected (radius of 20 mm) (same as in FIG. 4), the curvature radius is slightly small (set to a radius of 15 mm). As with FIGS. 3 and 4, the propagation of ultrasonic waves was shown by analysis. By making the curvature radius of the acoustic lens smaller than the curvature radius of the metal surface (FIG. 21A (B)), the ultrasonic wave transmitted from the acoustic lens to water is once diffused and then focused when entering the metal. As a result, it can be confirmed that the region where the ultrasonic waves are focused reaches a deeper position 2101 than when the radius of curvature of the acoustic lens is equal to the radius of curvature of the metal surface (position 401 in FIG. 21A).

FIG. 21B shows an inspection target when the sound field formed by the array sensor 2105 is changed in three patterns when the curvature to be inspected (radius 20 mm) and the curvature radius of the acoustic lens are close to each other (radius 18 mm). It is the result of analyzing the focal sound field in (metal).

  It can be confirmed that the focal length in the metal is changed by changing the delay time given to each element constituting the array sensor. For example, FIG. 21B (A) shows a result when a focused sound field is formed by an array sensor, and FIG. 21B (C) shows a result when a divergent sound field is formed by an array sensor. When the focused sound field is set compared to the position 2103 of the focal depth of the focus of the ultrasonic wave in the metal in the flat (unfocused) sound field of FIG. 21B (B), the super in the metal in (A). It can be seen that the position 2102 of the focal depth of the acoustic wave is shallower, and the focal position 2104 of the focal point of the ultrasonic wave when the divergent sound field is set is changed deeper. .

  By utilizing this effect, even when there is a variation in the radius of curvature of the metal surface to be inspected, the focal depth in the inspection object can be kept constant by changing the sound field formed by the array sensor 2105. Can be controlled.

  As an example, in FIG. 21C, when the curvature radius of the acoustic lens is fixed at a close value (radius 15 mm) and the curvature to be inspected is changed to radii 16, 20, and 25 mm, the focal sound field in the metal is almost the same. The result of the analysis is a constant value. Let us consider the case shown in FIG. 21C (A) where the metal field has a curvature of 20 mm and the sound field by the array sensor is flat. When the radius of curvature of the metal surface is 25 mm (FIG. 21C (B)), the focusing effect on the metal surface is reduced because the radius of curvature is increased. Therefore, in order to focus at a depth substantially the same as the focal depth 2106 shown in FIG. 21C (A), the sound field formed by the array sensor 2105 needs to be a focused sound field.

  Conversely, when the radius of curvature of the metal surface is 16 mm (FIG. 21C (C)), the focusing effect on the metal surface becomes stronger because the radius of curvature is reduced. Therefore, in order to focus at substantially the same depth as the focal depth 2106 shown in FIG. 21C (A), the sound field formed by the array sensor 2105 needs to be a divergent sound field.

  As described above, in the case of “combination 2” of the array sensor arrangement and the acoustic lens described above, when the sound field formed by the array sensor is changed, the curvature radius of the metal surface to be inspected varies. In this case, the depth of focus can be kept constant at a desired value.

  Next, with reference to FIGS. 22 and 23, the case where the ultrasonic probe described in the present embodiment is used as an inspecting device for a reactor internal structure of a nuclear power plant will be described below. The inspection apparatus mast 2210 is suspended from the work carriage 2202 on the operation floor 2201 in the reactor building of the nuclear power plant by the wire 2205 from the vertical movement mechanism 2203 on the work carriage 2202 to the reactor water 2206 in the reactor pressure vessel. Be taken down.

  The mast 2210 lowered in the reactor water 2206 passes through the upper lattice plate 2220 and the core support plate 2221 in the reactor pressure vessel and is seated on the CRD housing 2301. An articulated manipulator 2302 is installed on the mast 2210, and an inspection head 2303 including the ultrasonic probe 101 is attached to the tip of the articulated manipulator 2302.

  The signal cable, power cable, and high water pressure cable of the ultrasonic probe 101 and the manipulator 2302 are bundled together as a cable and a hose 2304 from the upper part of the mast 2210, extended to the operation floor 2201, and connected to the controller 2207. .

A base 2305 of the manipulator 2302 is attached to the mast 2210 and has a structure capable of vertical and rotational movement. The manipulator 2302 includes a plurality of bending indirects 2306 and rotating indirects 2307. A hand unit 2308 is provided at the tip of the manipulator 2302, and an inspection head 2303 including the ultrasonic probe 101, a probe pressing mechanism 2309, and a probe scanning mechanism 2310 can be gripped.

  The ultrasonic probe 101 can be moved by the scanning mechanism 2310 while following the curved surface of the CRD stub welded portion by the probe pressing mechanism 2309 and can perform ultrasonic inspection of the crack 104 of the welded portion. .

Rotation of mast 2210, control of articulated manipulator 2302, inspection head 2303
Operations such as (probe scanning and pressing) are controlled by an inspection apparatus controller 2207 on the operation floor 2201, and a control signal is transmitted using a signal cable 2208. The ultrasonic probe 101 built in the inspection head 2303 is controlled (and recorded) by an ultrasonic flaw detector 2209, and transmission / reception signals are transmitted to each other using a signal cable 2208.

  The configuration example of the inspection apparatus illustrated in FIGS. 22 and 23 can be applied to the same configuration in the second embodiment.

  FIG. 13 shows a second embodiment of the present invention, and as shown in the figure, an ultrasonic probe 1301 for applying ultrasonic waves is pressed against an inspection target 102 having a curved surface to detect flaws. The defects to be inspected are the same as in the first embodiment, such as the crack 104 opened on the curved surface side, the defect 106 inherent in the inspection object, and the like.

  The ultrasonic probe 1301 includes a transmitting or receiving element 1302 and an acoustic lens 1303.

  Between the inspection object 102 and the ultrasonic probe 1301, a contact medium (also called water or glycerin) such as water or glycerin is applied or filled as an intermediate medium in order to improve sound propagation. To do.

  An acoustic lens 103 having an intermediate characteristic between the inspection object 102 and the contact medium is used. For example, a synthetic resin such as acrylic, polystyrene, or polyimide is used. These materials have a longitudinal wave propagation speed of 2400 m / sec to 2900 m / sec, which is an intermediate sound speed between the inspection object 102 and the contact medium.

  In the second embodiment, it is assumed that the curvature radius of the acoustic lens may be along the curvature radius of the inspection object 102. In this case, as described in the first embodiment, since the radius of curvature of the acoustic lens is larger than the curvature radius that is the optimum value, the diffusion effect by the acoustic lens is weakened, and the focusing effect on the surface of the inspection object 102 is reduced. A phenomenon occurs in which the focal point is formed at a position shallower than the desired depth.

  In order to avoid this phenomenon and to efficiently propagate the ultrasonic wave to a deep part to be inspected, the ultrasonic wave generation / reception element 1302 is provided with a convex shape. By making the element 1302 convex, the diffusion effect due to the acoustic lens and the diffusion effect due to the shape of the element are added, canceling the focusing effect due to the concave surface of the inspection object 102, and transmitting ultrasonic waves to the deep part of the inspection object 102 Will be able to.

  The relationship between the curvature to be applied to the acoustic lens and the curvature to be applied to the element will be described with reference to FIGS. 14 and 15, the horizontal axis represents the ratio of the curvature radius of the acoustic lens (R shoe) and the curvature radius of the inspection object (R steel), and the vertical axis represents the curvature radius of the element (R element) and the inspection object. The ratio of the radius of curvature (R steel) is taken. FIG. 14 shows a case where the longitudinal sound velocity of the acoustic lens is 2400 m / second, and FIG. 15 shows a case where it is 2900 m / second.

  An acoustic lens having a radius of curvature larger than the radius of curvature of the acoustic lens determined as the optimum value recommended in the first embodiment is improved or the adhesion between the curved surface to be inspected and the ultrasonic probe is improved. When the flaw detection is used, the value of the R sensor / R steel ranges from about 0.6 corresponding to the optimum value in the first embodiment to 1.0 which means complete adhesion. be able to.

  An acoustic lens with a radius of curvature smaller than the optimum value should be avoided because the intensity of the ultrasonic wave inside the test object is reduced in order to form a divergent sound field inside the test object. It is physically difficult to exceed the radius of curvature of the object from the viewpoint of contact.

  When the value of the R sensor / R steel varies between 0.6 and 1.0, the curvature of the element is determined based on the following idea. That is, the recommended value in the first embodiment corresponds to the case where the acoustic lens has a curvature of about 0.6 times the curvature of the inspection object and the sensor has no curvature (flat). To evaluate the optimum value of the curvature of the element by analytically obtaining the curvature of the element when the curvature of the acoustic lens is changed by giving a constraint condition that can be regarded as equivalent to the diverging sound field at this time Can do.

  For example, when the ratio between the curvature of the acoustic lens and the radius of curvature of the concave surface to be inspected is about 0.6, the ratio of the curvature of the element and the curvature of the inspection target surface diverges to + ∞ in both FIGS. You can see that This corresponds to the fact that the element is flat. As the ratio of the curvature of the acoustic lens (the horizontal axis of the graph) is gradually increased from 0.6 toward 1.0, the ratio of the curvature radius of the element (the vertical axis of the graph) gradually increases from + ∞. When the ratio of the curvature of the acoustic lens becomes 1.0 and coincides with the curvature radius of the inspection object, the curvature radius of the element is about 3 to 4 times the curvature radius of the concave surface of the inspection object. .

  From this analysis result, when the acoustic lens follows the radius of curvature, the curvature radius of the element is set to a radius of curvature larger than three times the radius of curvature of the concave surface to be inspected. It can be seen that the ultrasonic wave can be incident to a deep part.

  If there is a variation in the radius of curvature of the inspection object, from the point of view of contactability, taking the smallest possible radius of curvature as a reference, the curvature radius of the element and the acoustic lens should be determined to deal with the variation. Is possible.

  Also in the second embodiment, as in the first embodiment, the elements constituting the array sensor are one-dimensional or two-dimensional as the ultrasonic generation / reception elements 105 constituting the ultrasonic probe. Can be arranged.

  Here, also in the second embodiment, as described in the first embodiment, the following two combinations can be considered regarding the arrangement of the array sensor and the arrangement of the acoustic lens. Combination 1 is when the element arrangement direction and the axial direction of the acoustic lens are parallel, and combination 2 is when the element arrangement direction and the axial direction of the acoustic lens are orthogonal.

  In the case of the combination 1, since the direction of the elements constituting the array sensor is the axial direction of the acoustic lens, the sound field generated by the array sensor has the curvature of the acoustic lens regardless of the delay time pattern applied to each element. It will be affected only by the radius. For this reason, on the cross-sectional view perpendicular to the axial direction of the acoustic lens, only one element is represented and displayed as shown in FIG. For this reason, the description (FIGS. 13, 14, and 15) of the normal sensor (sensor not having the array structure) and the description of the array sensor of “combination 1” can be regarded as common.

  On the other hand, in the case of the combination 2, since the curvature of the acoustic lens is attached in the direction of the element arrangement of the array sensor, the sound field by the array sensor changes depending on the delay time pattern given to each element. For this reason, on the cross-sectional view perpendicular to the axial direction of the acoustic lens, only one element is represented and displayed as shown in FIG.

  FIG. 16 shows an example in which elements are arranged one-dimensionally in a direction orthogonal to the axial direction of the acoustic lens. When the array sensor 1602 shown in FIG. 16 is used as the ultrasonic wave generation / reception element 105 constituting the ultrasonic probe, as shown in FIG. By changing the timing (delay time) that occurs, various sound fields with varying degrees of flatness, convergence, and divergence can be formed, focusing or changing according to the change in the radius of curvature of the concave surface to be inspected. The diverging sound field can be synthesized electronically.

Further, in the ultrasonic probe according to the second embodiment, in order to cope with the change in the radius of curvature of the inspection object, the acoustic sensor 1303 is compared with the acoustic lens (1603 or 1604) having a different radius of curvature. By using the element group 1605 forming the common and using the acoustic sensor having a different curvature in contact with the array sensor, an ultrasonic probe corresponding to a large number of curvature radii can be obtained.

  Here, the structure of the element of the array sensor brought into contact with the acoustic lens having a different curvature will be described with reference to FIGS. FIG. 17 shows a case where elements are arranged one-dimensionally, and FIG. 18 shows a case where elements are arranged two-dimensionally. In any case, there is a concern that when the element is brought into contact with the concave surface (1703 in FIG. 17), a difference in the amount of deflection occurs due to the difference in curvature between the top and bottom of the element, which may cause destruction or disconnection of the element. The

  Therefore, with respect to the elements constituting the array sensor (1701 in FIG. 17 and 1801 in FIG. 18) that are in close contact with the concave surface, each element is cut so that the cross-sectional shape becomes a trapezoidal shape. Can be improved.

  A manufacturing procedure in the case where the elements are arranged one-dimensionally as shown in FIG. 17 will be described with reference to FIG. 24 (A to C). First, ultrasonic elements are installed at appropriate intervals, and synthetic resin is poured into the periphery of the ultrasonic elements to produce a sheet-like ultrasonic element for a flexible array (FIG. 24A). Next, the element is cut so as to have a one-dimensional arrangement (FIG. 24B) and completed (FIG. 24C).

  A manufacturing procedure in the case of arranging the elements two-dimensionally as shown in FIG. 18 will be described with reference to FIGS. 25 (A to C). First, an ultrasonic element is arranged in a mold that is cut through a final two-dimensionally arranged trapezoidal shape portion (FIG. 25A). Next, a synthetic resin is poured into the mold (FIG. 25B) and removed from the mold to complete (FIG. 25C).

  The ultrasonic probe of the second embodiment is also controlled (and recorded) by the ultrasonic flaw detector 2209 as in the first embodiment, and the transmission / reception signals are transmitted to each other using the signal cable 2208. It has become.

  The present invention is employed in an ultrasonic probe that is used by being connected to an ultrasonic flaw detector in order to perform nondestructive inspection using ultrasonic waves.

It is a conceptual diagram in the time of a flaw detection operation | work of the ultrasonic probe which concerns on 1st Example of this invention. It is a graph regarding the optimal value factor of the acoustic lens used for the Example of this invention. It is explanatory drawing showing the focusing effect of the ultrasonic wave by the concave surface of the test object surface by a prior art example. It is another explanatory drawing showing the focusing effect of the ultrasonic wave by the concave surface of the inspection object surface. It is explanatory drawing which showed the relationship between the array element in the ultrasonic probe by the Example of this invention, the concave curved surface of test object, and an acoustic lens. It is explanatory drawing which showed the other relationship between the array element in the ultrasonic probe by the Example of this invention, the concave curved surface of test object, and an acoustic lens. Example of each sound field according to the relationship between the position of each element from one end in the arrangement direction of the array element in the embodiment of the present invention (when 24 elements are arranged at 1 mm pitch) and the delay time of ultrasonic generation It is the figure which visualized and showed the propagation of the ultrasonic wave in each sound field. It is the figure which showed the arrangement | sequence of the element of an array sensor employable in the Example of this invention, and arrangement | positioning with an acoustic lens. It is the figure which showed arrangement | positioning with the other arrangement | sequence of the element of the array sensor employable in the Example of this invention, and an acoustic lens. It is the figure which showed arrangement | positioning with other arrangement | sequence of an element of the array sensor employable in the Example of this invention, and an acoustic lens. It is the figure which showed further arrangement | positioning with the arrangement | sequence of the element of the array sensor employable in the Example of this invention, and an acoustic lens. It is the figure which showed the arrangement | positioning in the orthogonal | vertical both directions of the element of the array sensor employable for the Example of this invention, and arrangement | positioning with an acoustic lens. It is the figure which showed arrangement | positioning with the other arrangement | sequence in the orthogonal | vertical both directions of the element of the array sensor employable in the Example of this invention, and an acoustic lens. It is a conceptual diagram in the time of a flaw detection operation | work of the ultrasonic probe which concerns on 2nd Example of this invention. It is a figure explaining the relationship between the shoe of an ultrasonic probe and the curvature of a sensor in the 2nd example of the present invention. It is a figure explaining the relationship between the curvature of the shoe of an ultrasonic probe, and a sensor in the situation where the speed of sound of the acoustic lens in 2nd Example of this invention differs from the case of FIG. It is explanatory drawing explaining adjustment of the sound field of the ultrasonic wave in the 2nd Example of this invention. It is explanatory drawing of the element which has a trapezoid cross section employable with the 2nd Example of this invention. It is explanatory drawing of the element whose cross section of two orthogonal directions which can be employ | adopted by the 2nd Example of this invention is trapezoid. It is sectional drawing which shows an example of the internal structure of the ultrasonic probe in the Example of this invention. It is sectional drawing which shows another example of the internal structure of the ultrasonic probe in the Example of this invention. It is explanatory drawing showing the change of the depth of the focus position of an ultrasonic wave which changes with the relationship between the curvature of the acoustic lens of an ultrasonic probe, and the curvature of the curved surface to be examined. It is explanatory drawing showing the change of the depth of the focal position of the ultrasonic wave corresponding to each sound field of the ultrasonic wave in the acoustic lens of an ultrasonic probe. It is explanatory drawing showing the change of the depth of the focal position of an ultrasonic wave corresponding to the change of the curvature radius of the acoustic lens of an ultrasonic probe. It is the longitudinal cross-sectional view of the reactor pressure vessel and the peripheral part which showed the condition which is performing the test | inspection operation | work with the in-reactor inspection apparatus using the ultrasonic probe of this invention. It is a principal part enlarged view of FIG. It is explanatory drawing which shows the first half in the manufacturing process of the trapezoidal ultrasonic element which can be employ | adopted by the 2nd Example in this invention. It is explanatory drawing which shows the condition of the middle stage in the manufacturing process of the trapezoidal ultrasonic element which can be employ | adopted by the 2nd Example in this invention. It is explanatory drawing which shows the last stage of the manufacture process of the ultrasonic element whose cross section is employable in the 2nd Example in this invention. It is explanatory drawing which shows the first half of the manufacturing process of the orthogonal | vertical two-way cross section trapezoidal ultrasonic element which can be employ | adopted with the 2nd Example in this invention. It is explanatory drawing which shows the middle stage of the manufacture process of the orthogonal | vertical two-way cross section which can be employ | adopted with the 2nd Example in this invention, and a trapezoidal ultrasonic element. It is explanatory drawing which shows the final stage of the manufacturing process of the orthogonal | vertical two-way cross section which can be employ | adopted with the 2nd Example in this invention, and a trapezoid. It is explanatory drawing which shows the combination of arrangement | positioning of the array sensor and acoustic lens in this invention, and shows the example in which the axial direction of an acoustic lens corresponds with the arrangement direction of the element of an array sensor. It is explanatory drawing which shows the combination of arrangement | positioning of the array sensor and acoustic lens in this invention, and shows the example in which the axial direction of an acoustic lens is orthogonal to the arrangement direction of the element of an array sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Ultrasonic probe, 102 ... Inspection object, 103 ... Acoustic lens, 104 ... Crack, 105 ... Element for ultrasonic generation or / and reception, 106 ... Defect.

Claims (16)

An element for transmitting ultrasonic waves, an acoustic lens for propagating the ultrasonic waves to the concave curved surface portion to be inspected, and an element for receiving echoes of the ultrasonic waves from the inspection object via the acoustic lens In the ultrasonic probe of the ultrasonic flaw detector,
The surface of the acoustic lens facing the concave curved surface portion has a shape of a convex curved surface having a radius of curvature smaller than the radius of curvature of the concave curved surface portion,
The material of the acoustic lens is that the ultrasonic longitudinal wave velocity is slower than the longitudinal wave velocity in the inspection object, and the ultrasonic longitudinal wave velocity in the intermediate medium between the ultrasonic probe and the inspection object. An ultrasonic probe of an ultrasonic flaw detector characterized by being composed of an earlier material.   2. The ultrasonic flaw detection according to claim 1, wherein the shape of the convex curved surface is a convex curved surface having a curvature radius in a range of one-half to two-thirds of the curvature radius of the concave curved surface portion. The ultrasound probe of the device.   The ultrasonic probe of the ultrasonic flaw detector according to claim 1 or 2, wherein the element that transmits the ultrasonic wave and the element that receives the echo are array sensors.   4. The ultrasonic flaw detection apparatus according to claim 3, wherein the array sensor includes a transmitter and a receiver, and an array direction of elements of the array sensors for transmission / reception is directed to an axial direction of the acoustic lens. The ultrasound probe of the device.   4. The array sensor according to claim 3, wherein the array sensor includes a transmitter and a receiver, and an array direction of elements of the array sensors for transmission / reception is directed in a direction orthogonal to an axial direction of the acoustic lens. An ultrasonic probe for an ultrasonic flaw detector.   6. The element of each of the array sensors for transmission / reception according to claim 3, wherein the elements of each array sensor for transmission / reception are arranged in both directions of an axial direction of the acoustic lens and another direction orthogonal to the axial direction. An ultrasonic probe for an ultrasonic flaw detector.   The shielding plate according to any one of claims 1 to 6, wherein the acoustic lens is disposed inside the acoustic lens so as to separate a propagation path between the transmitted ultrasonic wave and the received echo. An ultrasonic probe of an ultrasonic flaw detector characterized by comprising: An element that transmits ultrasonic waves, an acoustic lens that propagates the ultrasonic waves to the concave curved surface portion of the inspection object, and an element that receives the ultrasonic echoes from the inspection object via the acoustic lens, In the ultrasonic probe of the ultrasonic flaw detector, the surface of the acoustic lens facing the concave curved surface portion has a convex curved shape,
An ultrasonic probe of an ultrasonic flaw detector, in which an element that transmits the ultrasonic wave and a element that receives the echo are provided with a curvature that protrudes in the same direction as the protruding direction of the convex curved surface.   9. The ultrasonic probe according to claim 8, wherein the curvature radius of the convex curved surface of the acoustic lens and the curvature radius of the concave curved surface portion to be inspected have the same curvature radius.   The ultrasonic probe of an ultrasonic flaw detector according to claim 8 or 9, wherein an element for transmitting the ultrasonic wave with a curvature larger than three times the radius of curvature of the concave curved surface portion to be inspected is arranged.   The ultrasonic probe of an ultrasonic flaw detector according to claim 10, wherein the element that transmits the ultrasonic wave and the element that receives the echo are array sensors.   12. The ultrasonic probe of an ultrasonic flaw detector according to claim 11, wherein the direction of the array of elements of the array sensor is oriented in the axial direction of the acoustic lens.   12. The ultrasonic probe of an ultrasonic flaw detector according to claim 11, wherein the direction of the array of elements of the array sensor is directed to another direction orthogonal to the axial direction of the acoustic lens.   12. The ultrasonic flaw detector according to claim 11, wherein the array sensor elements are arrayed in both directions of an axial direction of the acoustic lens and another direction orthogonal to the axial direction. Ultrasonic probe.   15. The cross-sectional shape of the element according to claim 11, wherein the cross-sectional shape of the element is a trapezoid in which a side is short and a side opposite to the central side of the radius of curvature of the acoustic lens is long. The ultrasonic probe of the ultrasonic flaw detector characterized by the above. The ultrasonic wave according to claim 15, wherein the shape of another cross section orthogonal to the cross section is a trapezoid in which a side is short and a side opposite to the central side of the radius of curvature of the acoustic lens is long. Ultrasonic probe for flaw detector.

Images