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JP2007114075

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DESCRIPTION JP2007114075
The present invention provides an ultrasonic probe capable of focusing an ultrasonic wave also
on a deep position of an inspection object having a concave surface. SOLUTION: An acoustic lens
103 having a radius of curvature of 1/2 to 2/3 of a radius of curvature of a concave surface of
an inspection object 102 is placed between an element 105 for ultrasonic wave generation and /
or reception and the inspection object 102. Recession of the ultrasonic wave by the concave
surface of the inspection object 102 is reduced by refraction of the ultrasonic wave in the
diffusion direction of the ultrasonic wave when propagating from the acoustic lens 103 to the
intermediate medium (contact medium). The ultrasonic waves are focused at a deep portion
(about several times the radius of curvature of the concave surface), and the echoes of the
ultrasonic waves from the defect 106 at the deep portion are received by the back propagation
path. [Selected figure] Figure 1
Ultrasonic probe of ultrasonic flaw detector
[0001]
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
target and an inspection surface to be inspected has a concave surface.
[0002]
An ultrasonic method (ultrasonic flaw detection method) has conventionally been generally used
as a nondestructive inspection method of a solid or the like that permits both longitudinal wave
03-05-2019
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and transverse wave propagation, such as metal.
Among them, the following inspection methods are conventionally known as inspection methods
for curved portions, in particular.
[0003]
For example, according to Non-Patent Document 1, which is one of the JIS standards for
ultrasonic flaw detection, "the probe is to be used with a shoe fitted to the shape of the flaw
detection surface. As described above, when the surface to be inspected is a curved surface, a
method using an acoustic wedge called a shoe is generally used.
[0004]
Further, in the case of a curved surface having a large radius of curvature of the surface to be
inspected, according to Non-Patent Document 2, "the radius of the flaw detection surface is 50
mm or more and less than 1500 mm, and the thickness to outer diameter ratio is 16% or less
Regarding the ultrasonic flaw detection test method for welds of joints, "does not perform curved
surface processing on the contact surface of the probe" and, regarding the influence of curvature,
there is a method to correct for changes in refraction angle and sensitivity changes. Have been
described.
[0005]
The above method is a description of an oblique flaw detection method using sound waves
propagating in an oblique direction.
Besides this, there is a nondestructive inspection method using an ultrasonic wave called a TOFD
method. The TOFD method is a method widely used to measure the depth of the end of a crack to
be inspected, and according to Patent Document 1 "Ultrasonic TOFD method probe and flaw
detection method", the object to be inspected is When the surface is a curved surface, there is a
description that "the contact surface of the probe holder in contact with the curved surface
portion of the object is formed in a shape along the curved surface portion of the object". The
radius of curvature and the radius of curvature of the contact surface of the probe have the same
value.
03-05-2019
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[0006]
As described above, in the conventional ultrasonic inspection apparatus, the curved surface of
the contact surface of the ultrasonic probe is matched as much as possible to the curved surface
shape of the surface to be inspected to emphasize the contact property of the curved surface, and
the curvature is large. In this case, the contact surface of the probe remains flat, and by filling a
couplant called couplant (water, machine oil, glycerin, etc.) between the probe and the inspection
object, the ultrasonic Methods to improve the propagation efficiency were common.
[0007]
JP, 2004-53462, A Appendix 2 of "Method of ultrasonic flaw detection of carbon steel and low
alloy steel forgings", JIS G 0587, "Method of ultrasonic flaw detection by oblique angle method of
forged steel articles" JIS Z 3060, "Steel welded portion Appendix 4 "Testing method for welded
joints in longitudinal joints" of Ultrasonic test method
[0008]
The above-described method is effective when the surface of the metal to be inspected is a
concave (or convex) surface having a gentle curvature or when the inspection area is relatively
limited to the vicinity of the surface.
However, if the surface is concave with a small radius of curvature and the area to be inspected is
deep (for example, about 1 to several times compared to the radius of curvature), the ultrasonic
wave deep area while maintaining sufficient strength It was not possible to propagate it.
[0009]
If the object to be inspected is a metal with a relatively high sound velocity and a large density,
when the ultrasonic wave is incident on the concave surface, the concave shape acts as an
acoustic lens, and the ultrasonic wave There is a region where the strength is weakened, that is, a
flaw detection limit region.
For this reason, ultrasonic flaw detection of the deep part of the metal whose surface is concave
03-05-2019
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shape has been considered difficult.
[0010]
An example is given and demonstrated using FIG.3 and FIG.4. FIG. 3 is a straight line showing the
result of analysis of ultrasonic wave propagation when an ultrasonic probe 302 generating a
vertical beam is brought close to an inspection object 304 whose surface is concave (curvature
radius of 20 mm) and brought close It is the figure shown by (sound ray). It is assumed that
water is filled as an intermediate medium 303 between the ultrasonic probe 302 and the
inspection object 304.
[0011]
From the results 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 test object 304, and the ultrasonic
wave is focused at the region 305 in the test object 304. The flaw detection limit area 301 in this
case is about 0.3 times the radius of curvature of the concave shape of the inspection object 304.
The longitudinal sound velocity of the inspection object 304 is 5900 m / s, and the longitudinal
sound velocity of water is 1500 m / s.
[0012]
Next, the situation shown in FIG. 4 is slightly improved. The difference between FIG. 3 and FIG. 4
is that an acoustic lens (also referred to as a shoe) made of synthetic resin is used as an
intermediate medium between the ultrasonic probe 302 and the inspection object 304. Here, the
longitudinal sound velocity of the synthetic resin is 2700 m / sec. The acoustic lens 402 is in
close contact with the curvature of the inspection object 304.
[0013]
In the case of FIG. 4, since the difference between the sound velocity of the inspection object
(metal) and the sound velocity of the intermediate medium (synthetic resin) is smaller than the
difference between the sound velocities of metal and water, the refraction at the surface to be
inspected becomes gentle. The ultrasonic wave is focused on the area 403, and it is understood
that the flaw detection limit area 401 is about 2 to 3 times as deep as that in the case where the
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intermediate medium is water.
[0014]
The range of this critical area depends on the radius of curvature of the surface to be inspected
and the sound velocity ratio of the object to be inspected (metal) to the intermediate medium, the
radius of curvature of the metal surface to be inspected is R, and the longitudinal acoustic
velocity of metal to V2 Assuming that the sound velocity 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 velocity ratio γ = V1 / V2.
In the case of γ (water / metal) = 1500/5900 = 0.254, with respect to the concave curvature
radius R, 0.34 × R is the flaw detection limit depth. Further, in the case of 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 of FIG. 3 and FIG.
[0015]
As described above, since the curvatures of the contact surface of the inspection object 304 and
the acoustic lens 402 of the ultrasonic probe are matched, ultrasonic flaw detection in a deep
region exceeding the flaw detection limit distance determined depending on the sound velocity
ratio of both There was a problem that it was difficult.
[0016]
Furthermore, if the contact surface of the ultrasonic probe is set to substantially the same value
as the curvature radius of the surface of the inspection object 304, there are many cases where
the shape of the inspection object varies due to machining and welding, In such a case, there is a
problem that adhesion with the inspection object can not be maintained, and the incidence
efficiency of ultrasonic waves to the inspection object is lowered.
[0017]
Therefore, the problem to be solved by the present invention is a concave surface to be
inspected, and even if the inspection region to be inspected is a region deeper than the curvature
radius of the concave surface, the ultrasonic waves are concentrated on the inspection region
Providing an ultrasound probe that can be transmitted.
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[0018]
The 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 surface
portion to be inspected, and an echo of the ultrasonic wave from the inspection object via the
acoustic lens. In an ultrasonic probe of an ultrasonic flaw detector including a receiving element,
a shape of a convex curved surface having a radius of curvature smaller than a radius of
curvature of the concave curved surface, the surface of the acoustic lens facing the concave
curved surface And the material of the acoustic lens is an ultrasonic wave in an intermediate
medium between the ultrasonic probe and the object to be inspected, and a longitudinal wave
speed of ultrasonic waves is slower than a longitudinal sound speed in the object to be inspected
The ultrasonic probe of the ultrasonic flaw detector according to the present invention is
characterized by being made of a material faster than the longitudinal sound velocity.
[0019]
Such an ultrasonic probe is used in connection with an ultrasonic flaw detector, and when an
electrical signal is given from the ultrasonic flaw detector to an element that transmits ultrasonic
waves, the element that transmits ultrasonic waves exceeds the electrical signal. The ultrasonic
waves are transmitted into the acoustic lens and converted into acoustic vibration, and the
ultrasonic waves are refracted when propagating from inside the acoustic lens to the
intermediate medium, and the ultrasonic waves propagate in the intermediate medium in the
diffusion direction and from the intermediate medium When ultrasonic waves enter into the
inspection object, the ultrasonic waves are refracted and propagate in the inspection object in the
focusing direction.
As described above, since the ultrasonic wave is diffused immediately before the ultrasonic wave
propagates to the object to be inspected, the ultrasonic wave is focused at a deeper position of
the object to be inspected as compared with the case where the ultrasonic wave does not once go
through the diffusion process.
If there is a reflection source of ultrasonic waves in the area where the ultrasonic waves are
focused, the ultrasonic waves are reflected by the reflection source and returned to the means for
receiving the echo of the ultrasonic waves as echo and received back to the electrical signal. It is
converted and input to the ultrasonic flaw detector, and inspection results such as the presence
or absence of the reflection source are obtained by the ultrasonic flaw detector.
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[0020]
It may be possible to add the requirements described below to such a basic configuration.
(1) Means for transmitting and receiving ultrasonic waves, Elements for generating and receiving
ultrasonic waves adopted as means for receiving, and a half to three minutes of the curvature
radius of the concave surface to be inspected by the acoustic lens A convex acoustic lens having
a radius of curvature in the range of 2.
(2) A transducer array comprising a plurality of transducers arranged in at least one direction as
an ultrasonic wave generating means and an ultrasonic wave receiving element adopted as
means for transmitting and receiving ultrasonic waves, 2 Have at least one array sensor. (3) The
acoustic lens has a shielding plate acoustically blocking an acoustic propagation region of the
transmitted ultrasonic wave and the received echo inside the acoustic lens. (4) As the acoustic
lens, use a medium having a longitudinal sound velocity of 2400 m / sec to 2900 m / sec.
[0021]
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 surface
portion to be inspected, and an echo of the ultrasonic wave from the inspection object via the
acoustic lens. And a receiving element, and the surface of the acoustic lens facing the concave
surface portion is the same as the projecting direction of the convex surface in an ultrasonic
probe of an ultrasonic flaw detector having the shape of a convex surface. It is an ultrasonic
probe of an ultrasonic flaw detector including an element for transmitting the ultrasonic wave
with a curvature projecting in a direction and an element for receiving the echo.
[0022]
Even in such an ultrasonic probe, it is used by being connected to an ultrasonic flaw detector,
and when an electric signal is applied from the ultrasonic flaw detector to an element that
transmits ultrasonic waves, the element that transmits ultrasonic waves is An electrical signal is
converted into ultrasonic vibration, and ultrasonic waves are transmitted in the diffusion
direction into the acoustic lens, and the ultrasonic waves propagate in the diffusion direction into
the acoustic lens, and then propagate in the focusing direction when propagating inside the
03-05-2019
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inspection object Therefore, the ultrasonic waves are focused at a deeper position of the object to
be inspected than when the ultrasonic waves do not undergo the diffusion process once.
If there is a reflection source of ultrasonic waves in the area where the ultrasonic waves are
focused, the ultrasonic waves are reflected by the reflection source and returned to the means for
receiving the echo of the ultrasonic waves as echo and received back to the electrical signal. It is
converted and input to the ultrasonic flaw detector, and inspection results such as the presence
or absence of the reflection source are obtained by the ultrasonic flaw detector.
[0023]
It may be possible to add the requirements described below to such other basic configurations.
(5) A convex acoustic lens having a radius of curvature along the radius of curvature of the
concave surface to be inspected, and a convex shape having a radius of curvature greater than
three times the radius of curvature of the concave surface to be inspected Providing an element
for ultrasonic wave generation and / or reception. (6) The ultrasonic probe according to (5)
comprises a transducer array composed of a plurality of transducers arranged in at least one
direction as an element for ultrasonic wave generation and / or reception. , Can have an array
sensor. (7) The ultrasonic probe according to (6) can be characterized in that the cross-sectional
shape of the plurality of transducers constituting the array sensor is trapezoidal.
[0024]
As described above, according to the present invention, even when the surface to be inspected is
a concave surface and the region to be inspected is deep (for example, about 1 to several times as
large as the radius of curvature) Can be propagated for focusing in a deep area, and ultrasonic
flaw detection can be enabled in the deep part of the concave surface.
[0025]
In the embodiment of the present invention, in the case of inspecting the presence or absence of
a flaw of an inspection object by using a concave metal material as an inspection object, the
material (medium) of the acoustic lens has a longitudinal acoustic velocity of about 2400 m / s to
2900 m / s. The intermediate material is made of synthetic resin such as acrylic, polystyrene,
polyimide, etc., and the metal to be inspected has a longitudinal sound velocity of about 5900 m
/ sec and a longitudinal sound velocity of water or glycerin of about 1500 m / sec. It
demonstrates below as what implements ultrasonic flaw detection via a medium.
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[0026]
An ultrasonic probe is used in connection with an ultrasonic flaw detector, and an element for
transmitting an ultrasonic wave when an electrical signal is given to the means for transmitting
an ultrasonic wave from the ultrasonic flaw detector, and a concave surface portion to be
inspected In the ultrasonic probe of an ultrasonic flaw detector including an acoustic lens for
propagating the ultrasonic wave and an element for receiving an echo of the ultrasonic wave
from the inspection object via the acoustic lens, the concave portion The surface of the acoustic
lens facing the curved surface has a shape of a convex curved surface having a radius of
curvature smaller than the curvature radius of the concave surface, and the material of the
acoustic lens has the longitudinal wave velocity of ultrasonic waves as the inspection object It is
made of a material that is slower than the longitudinal acoustic velocity of the inside and faster
than the longitudinal acoustic velocity of the ultrasonic wave in the intermediate medium
between the ultrasonic probe and the inspection object.
[0027]
When an element transmitting an ultrasonic wave receives an electrical signal from an ultrasonic
flaw detector, the element converts the electric signal into ultrasonic vibration, and an ultrasonic
wave is transmitted into the acoustic lens to transmit an ultrasonic wave from the acoustic lens
to the intermediate medium. Propagates in the diffusion direction, and then propagates in the
focusing direction when ultrasonic waves propagate from the intermediate medium into the
inspection object.
Therefore, since the ultrasonic wave is diffused immediately before the ultrasonic wave
propagates to the object to be inspected, the ultrasonic wave is focused at a deeper position of
the object to be inspected as compared with the case where the ultrasonic wave does not go
through the diffusion process once.
If there is a reflection source of ultrasonic waves in the area to which the ultrasonic waves are
focused, the ultrasonic waves are reflected by the reflection source and returned to the means for
receiving the echo of the ultrasonic waves as echo and received to receive the echoes. 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 of the ultrasonic flaw detector and the inspection result such as the
presence or absence of the reflection source It can be judged.
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[0028]
As described above, according to the embodiment of the present invention, it is possible to
provide an ultrasonic probe capable of focusing the ultrasonic wave at a deep position to be
inspected.
[0029]
By adding the aforementioned requirements (1) to (4) to such a basic configuration, the following
characteristic effects can be added for each added requirement.
That is, according to the ultrasonic probe adopting the above requirement (1), the ultrasonic
wave transmitted from the ultrasonic wave generation element propagates in the acoustic lens
before propagating to the inside of the metal.
As the medium of the acoustic lens, the material is used because the longitudinal sound velocity
is usually set faster than water (1500 m / s) and slower than metal (5900 m / s). For example, as
described in the requirement of (4), a medium having a velocity of about 2400 m / sec to 2900
m / sec as the longitudinal wave velocity propagating through the acoustic lens, for example, a
synthetic resin such as acrylic, polystyrene, polyimide, etc. An acoustic lens can be used.
[0030]
When ultrasonic waves propagating in the acoustic lens are incident from the acoustic lens to the
intermediate medium, that is, from the medium with high sound velocity to the slow medium, the
progress of the ultrasonic waves by the refraction phenomenon due to the convex shape of the
convex type acoustic lens surface The direction changes in the diffusion direction.
[0031]
Furthermore, when the ultrasonic wave is incident from the intermediate medium to the metal
material to be inspected, that is, from the medium having a low sound velocity to the fast
medium, the traveling direction of the ultrasonic wave is Change in the focusing direction.
[0032]
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At this time, in general, the focusing effect by the metal surface has a stronger influence by the
diffusion effect by the acoustic lens and the focusing effect by the metal surface.
In the ultrasound probe adopting the requirement of (1), the radius of curvature of the acoustic
lens is set to a value smaller than the radius of curvature of the metal surface (one half to two
thirds of the radius of curvature of the metal surface) By doing this, a stronger diffusion effect
can be obtained as compared with the conventional closely-contacted acoustic lens, and the
strong diffusion effect on the metal surface can be mitigated.
In addition, since a small radius of curvature is set as compared to a metal surface, it is possible
to press the probe against a curved surface even when the radius of curvature of the metal
surface has variations of about several millimeters to about 10 millimeters. , The efficiency of the
ultrasound to the inspection object is improved.
[0033]
The focusing effect of the acoustic lens will be described with reference to FIG. In FIG. 21, as
described above, in the case of an intermediate medium having the same radius of curvature as
the curvature to be inspected (radius 20 mm) (same as FIG. 4) and when the radius of curvature
is slightly small (radius 15 mm) As in FIGS. 3 and 4, the analysis of the ultrasonic wave
propagation was shown. By making the radius of curvature of the acoustic lens smaller than the
radius of curvature of the metal surface, the ultrasonic waves transmitted from the acoustic lens
to water are once diffused and then focused when incident on the metal, resulting in When the
radius of curvature of the acoustic lens is equal to the radius of curvature of the metal surface
(401 in the upper view of FIG. 21), it can be confirmed that the ultrasonic waves reach to a
deeper position 2101.
[0034]
In addition, according to the ultrasonic probe adopting the requirement (2) described above,
when there is variation in the metal surface, the optimum focusing corresponding to the radius of
curvature of the metal surface is made use of by utilizing the characteristics of the array sensor.
Ultrasonic waves can be formed.
[0035]
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11
Here, the array sensor is a sensor for ultrasonic wave generation and reception which is used for
a phased array type ultrasonic flaw detection method.
In addition, since the phased array method is also referred to as 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 wave generating elements consisting of piezoelectric elements
are arranged in an array. The electric signals that trigger the generation of ultrasonic waves are
delayed by a predetermined time and given to each element of the array sensor, and the
ultrasonic waves generated from the respective elements are superimposed to form a synthetic
wave. The conditions such as transmission angle and reception angle of ultrasonic waves to the
test object, transmission position and reception position, or position where the combined wave
interferes and strengthens each other, that is, focal position, etc. are changed at high speed by
electrical control. It is an ultrasonic flaw detection method that makes it possible to Here, the
timing of ultrasonic wave generation and / or reception given to each element will be hereinafter
referred to as a delay time pattern.
[0036]
By using the array sensor in this way, when the curvature radius of the object to be inspected
varies, as described in (1), to the contactability obtained by making the curvature radius of the
acoustic lens smaller than the curvature radius of the metal surface. In addition, by electronically
changing the delay time pattern given to each element constituting the array sensor, it is possible
to control the diverging effect corresponding to the curvature radius of the inspection object
having variation, and the effect of variation can be obtained. In response, it becomes possible to
transmit a diverging ultrasound beam which cancels out the strong focusing effect by the metal
surface.
[0037]
Moreover, according to the probe which adopted the requirement of (3), the noise which
generate | occur | produces because an ultrasonic wave carries out multiple reflection in an
acoustic lens can be suppressed.
[0038]
Due to the structure in which the ultrasonic wave generating element and the acoustic lens are in
03-05-2019
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contact, the multiple reflections of the ultrasonic wave remain like reverberation in the acoustic
lens due to the reflection by the boundary layer between the acoustic lens and the intermediate
medium, resulting in a strong noise signal Sex is a concern.
In order to avoid this noise, in addition to physically separating the element for ultrasonic wave
generation and the element for ultrasonic wave reception, a sound insulation board (the material
is, for example, cork or rubber sound insulation in the acoustic lens) By providing the reception
device, multiple reflection noise in the acoustic lens can be prevented from being mixed into the
element for reception.
[0039]
In an ultrasonic probe according to another embodiment of the present invention, an element for
transmitting an ultrasonic wave, an acoustic lens for propagating the ultrasonic wave to a
concave surface portion to be inspected, and an echo of the ultrasonic wave from the inspection
object An ultrasonic probe of an ultrasonic flaw detection apparatus, comprising: an element for
receiving the acoustic lens via the acoustic lens, and a surface of the acoustic lens facing the
concave surface portion has a convex curved surface shape; An element that transmits the
ultrasonic wave and an element that receives the echo are disposed with a curvature that
protrudes in the same direction as the protruding direction of the curved surface.
[0040]
Even in such an ultrasonic probe, it is used by being connected to an ultrasonic flaw detector,
and when an electric signal is applied from the ultrasonic flaw detector to an element that
transmits ultrasonic waves, the element that transmits ultrasonic waves is An electrical signal is
converted into ultrasonic vibration, and ultrasonic waves are transmitted in the diffusion
direction into the acoustic lens, and the ultrasonic waves propagate in the diffusion direction into
the acoustic lens, and then propagate in the focusing direction when propagating inside the
inspection object Therefore, the ultrasonic waves are focused at a deeper position of the object to
be inspected than when the ultrasonic waves do not undergo the diffusion process once.
If there is a reflection source of ultrasonic waves in the area where the ultrasonic waves are
focused, the ultrasonic waves are reflected by the reflection source and returned to the means for
receiving the echo of the ultrasonic waves as echo and received back to the electrical signal. It is
converted and input to the ultrasonic flaw detector, and inspection results such as the presence
or absence of the reflection source are obtained by the ultrasonic flaw detector.
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Here, as the medium of the acoustic lens, a material whose longitudinal sound velocity is set to
be faster than water (1500 m / sec) and slower than the metal to be inspected (5900 m / sec) is
used.
[0041]
It is also possible to add the requirements of the above (5) (6) (7) to such other basic
configuration.
[0042]
When ultrasonic waves propagating in the acoustic lens are incident from the acoustic lens to the
intermediate medium, that is, from the medium with high sound velocity to the slow medium, the
progress of the ultrasonic waves by the refraction phenomenon due to the convex shape of the
convex type acoustic lens surface The direction changes in the diffusion direction.
[0043]
Furthermore, when the ultrasonic wave is incident from the intermediate medium to the metal
material to be inspected, that is, from the medium having a low sound velocity to the fast
medium, the traveling direction of the ultrasonic wave is Change in the focusing direction.
[0044]
At this time, in general, the focusing effect by the metal surface has a stronger influence by 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 equal to the curvature radius of the metal surface, and a sufficient
diffusion effect can not be obtained.
Therefore, by keeping the curvature of the convex surface (the radius of curvature greater than 3
times the radius of curvature of the metal surface to be inspected) on the element itself that
generates and / or receives ultrasonic waves, the adhesion state is maintained on the metal
surface The strong diffusion effect of ultrasonic waves can be obtained, and the strong focusing
03-05-2019
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effect on the metal surface can be mitigated.
[0045]
Further, according to the ultrasonic probe to which the requirement (6) described above is added,
the shape is determined according to the minimum value among the concave curvature radii of
the metal surface assumed within the range of the variation. When there is variation in the metal
surface, it is possible to form an optimal focused ultrasonic wave corresponding to the radius of
curvature of the metal surface to be inspected by utilizing the characteristics of the array sensor.
[0046]
In addition, according to the ultrasonic probe to which the requirement of (7) described above is
added, when forming an array sensor on a curved surface such as in an acoustic lens, the crosssectional shape of the element is trapezoidal. The shape followability of the element is improved.
[0047]
The improvement of the shape followability is very effective, for example, in the following cases.
When there are many types of curvature radius of the curved surface to be inspected, multiple
acoustic lenses with different curvature radius are prepared, and by using the array lens in close
contact with the acoustic lens, various curvature radii can be handled. It can be used as a curved
surface ultrasonic probe.
At this time, since the array sensor repeats adhesion and peeling to the surface having different
curvatures, a notch is provided on the surface (the side not in contact with the concave surface)
of the elements constituting the array sensor to follow the curved surface. It is possible to
construct an improved and reliable ultrasound probe.
[0048]
Hereinafter, the ultrasonic flaw detection method and apparatus according to the present
invention will be described in detail by the illustrated embodiments.
03-05-2019
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The inspection target is metal, and the inspection surface of the metal is a concave surface with a
radius of curvature of several tens to hundreds of millimeters, and it is assumed for inspection of
a base material and welds of several tens to hundreds of millimeters in thickness. There is.
[0049]
FIG. 1 shows a first embodiment of the present invention, as shown in the figure, in which an
ultrasonic probe 101 to which an ultrasonic wave is incident is pressed against an inspection
target 102 to be inspected to perform flaw detection. The defect to be inspected is, for example, a
crack 104 opened on the curved surface side or an inherent defect such as the defect 106. The
element 105 in the ultrasonic probe 101 is a transmitting element that generates an ultrasonic
wave by the applied electric signal and a receiving element that receives an ultrasonic wave and
generates an electric signal (both elements are identical. And the acoustic lens 103. An ultrasonic
flaw detector may be used so that the transmission element and the reception element are shared
by one element and switched between generation of an ultrasonic wave and reception of an
ultrasonic echo so that the ultrasonic flaw detector can be used. The feeler is equipped with one
element that is also used for transmission and reception.
[0050]
The application destination of the embodiment is ultrasonic inspection of a metal (for example,
stainless steel) having a concave surface and a weld thereof, and the curved surface of the
inspection object 102 is locally a part of a cylindrical surface or one of a spherical surface. It
shall be considered to be formed from a part. Further, although the crack 104 opened on the
curved surface side is shown in FIG. 1, the present invention can be applied to a crack not
necessarily opened on the curved surface.
[0051]
Between the inspection object 102 and the ultrasonic probe, a couplant (also called couplant)
such as water or glycerin is applied or filled as an intermediate medium to improve sound
propagation. .
[0052]
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As the acoustic lens 103, one having an intermediate characteristic between the inspection object
102 and the contact medium is used.
For example, synthetic resins such as acrylic, polystyrene, and polyimide are used. In these
materials, the propagation velocity of the longitudinal wave is from 2400 m / sec to 2900 m /
sec, and the sound velocity is intermediate between the inspection object 102 and the contact
medium.
[0053]
The optimum value of the radius of curvature of the acoustic lens depends on the radius of
curvature of the inspection object 102, the longitudinal wave velocity of the medium of the
acoustic lens, the longitudinal wave velocity of the intermediate medium, and the sound velocity
ratio of the longitudinal wave velocity of the inspection object 102. For example, when the sound
velocity of the acoustic lens is 2700 m / s, the sound velocity of the intermediate medium is
1500 m / s, and the sound velocity of the inspection object 102 is 5900 m / s, the optimal
curvature radius of the acoustic lens with respect to the curvature radius R is 0.6 × R. It can be
approximately evaluated. Here, the ratio of the radius of curvature R of the surface to be
inspected to the radius of curvature of the optimum acoustic lens will be referred to as an
optimum value factor.
[0054]
Here, "optimum" means a case where the focusing effect by the concave surface of the inspection
object 102 is satisfied by the diverging effect by the convex surface of the acoustic lens, and the
curvature radius of the acoustic lens is larger than the optimum value. In such a case, the
diffusion effect of the acoustic lens is weakened, so that the focusing effect on the surface of the
inspection object 102 is overcome, and a phenomenon occurs in which the focus is formed at a
shallow position compared to the desired depth.
[0055]
Conversely, if the radius of curvature of the acoustic lens is smaller than the optimum value, a
diverging sound field is formed inside the inspection object 102 because the diffusion effect by
the acoustic lens is superior to the focusing effect by the surface of the inspection object 102 It
will be.
03-05-2019
17
[0056]
FIG. 2 is a graph showing analysis results in the case where the sound velocity of the metal to be
inspected is 5500 m / s and 6000 m / s, with the sound velocity of the acoustic lens taken on the
horizontal axis and the optimum value factor taken on the vertical axis.
When the sound velocity of the acoustic lens is between 2400 m / s and 2900 m / s, the radius
of curvature of the surface to be inspected with respect to the typical longitudinal sound speed
(5500 to 6000 m / s) of metallic materials such as stainless steel The ratio of R to the radius of
curvature of the optimal acoustic lens is within the range of 1/2 to 2/3, and the radius of
curvature of the acoustic lens is in the vicinity of the above values. It is possible to confirm that
the focusing effect of the surface to be inspected and the diffusion effect by the acoustic lens
cancel each other out and ultrasonic waves are efficiently incident to the deep part of the object
to be inspected.
[0057]
Such a thing can also be obtained by using a normal piezoelectric element as the ultrasonic wave
generating and / or receiving element 105, and it is possible to focus the ultrasonic wave to a
deep part.
However, in order to improve the S / N ratio by reducing the multiple reflection echo in the
acoustic lens and to follow the change in the curvature radius of the object to be inspected, the
ultrasonic wave generating or / and receiving element 105 constituting the ultrasonic probe. As
shown in FIG. 5A and FIG. 5B, an array sensor may be used.
[0058]
In an ultrasonic probe 501 having an array sensor, a plurality of elements 502 constituting the
array sensor are arranged one-dimensionally or two-dimensionally.
[0059]
03-05-2019
18
The features of the array sensor will be described with reference to FIG.
The array sensor is composed of small pieces of piezoelectric elements capable of transmitting
and receiving ultrasonic waves, and a delay time is given to the timing at which each element
generates ultrasonic waves by control from an ultrasonic flaw detector, thereby By changing the
state of interference of the generated ultrasonic waves, various sound fields such as focusing,
collimation, and divergence can be formed.
[0060]
FIG. 6A shows an example of a pattern of delay time with respect to a diverging sound field and
an example of a sound field (a cross-sectional view including the normal direction of the sensor
surface of a 1 MHz array element of 2 MHz, 1 mm × 24 elements) ) Shows a flat example, and
FIG. 6C shows an example of calculation of divergence. By changing the pattern of the timing
(delay time) of ultrasonic wave generation from the element, it is understood that the sound field
is changing from focusing to divergence.
[0061]
For example, in the case of arranging the elements 502 one-dimensionally, the following two
combinations can be considered depending on the relationship with the orientation of the
acoustic lens. When 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, the
combination 2 corresponds to the element arrangement direction of the elements constituting
the array sensor and the acoustic lens 103. This is the case where the axial directions are
orthogonal as shown in FIG. 26B.
[0062]
In the case of 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 pattern of delay time given to each element. It will be affected only by the radius of
curvature.
[0063]
03-05-2019
19
For this reason, only one element is represented on the cross-sectional view (FIG. 5A)
perpendicular to the axial direction of the acoustic lens.
Therefore, in the case of explaining the effect of the acoustic lens, in the case of pattern 1, it can
be regarded as the same as the explanation in the case where the ultrasonic probe 101 is not an
array structure. The descriptions (FIGS. 1, 2 and 21A) of (sensors not having array structure) and
the description of the “combination 1” array sensor can be regarded as common.
[0064]
On the other hand, in the case of combination 2, the curvature of the acoustic lens is attached in
the direction of the array of elements of the array sensor, so the sound field by the array sensor
changes according to the pattern of delay time given to each element.
[0065]
A specific structure of the array sensor (arrangement of elements and acoustic lens) will be
described with reference to FIGS. 7 to 12.
FIGS. 7 and 8 correspond to the case of the above-mentioned “combination 2” array sensor, in
which the axial direction of the acoustic lens is orthogonal to the arrangement direction of the
elements.
[0066]
In FIG. 7, the array sensor group 701 and the array sensor group 702 are disposed on the left
and right with the sound insulation plate 703, and in FIG. 8 the array sensor group 801 and the
array sensor group 802 with the sound insulation plate 803 interposed. Are arranged at the top
and bottom. These types of array sensors are suitable, for example, for the inspection of a defect
704 that has entered horizontally with respect to the inspection object 102.
[0067]
03-05-2019
20
On the other hand, in the case of the array sensor shown in FIG. 9 and FIG. 10, this corresponds
to the case of the above-mentioned “combination 1” array sensor, where the axial direction of
the acoustic lens and the direction of element arrangement are parallel. In FIG. 9, the array
sensor group 901 and the array sensor group 902 are disposed on the left and right with the
sound insulation plate 903 interposed therebetween, and in FIG. 10, the array sensor group
1001 and the array sensor group 1002 are interposed between the sound insulation plate 1003.
Are arranged at the top and bottom. These types of sensors are suitable, for example, for the
inspection of the defect 904 entering in the vertical direction with respect to the inspection
object 102.
[0068]
In the case of a change in the radius of curvature of the inspection object, in the case of the array
sensor shown in FIGS. 7 and 8, the elements are arranged on the curved side of the acoustic lens,
so the delay as shown in FIG. By controlling the time, it is possible to electronically control the
degree of focusing or divergence of the ultrasonic wave transmitted inside the test object, so it is
easy to follow the radius of curvature of the test object.
[0069]
However, in the array sensor shown in FIG. 9 and FIG. 10, since the elements are not arranged on
the side where the curvature of the acoustic lens is present, it is difficult to cope with the
curvature change of the surface to be inspected.
[0070]
Then, the improvement plan of the array sensor shown in FIG.9 and FIG.10 is shown in FIG.11
and FIG.12.
The array sensor group 901 and the array sensor group 902 in FIG. 9 are further divided into
three rows 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 rows to form an array sensor group 1201 and an array sensor group
1202 (FIG. 12). By arranging the elements constituting the array sensor in a two-dimensional
03-05-2019
21
manner as described above, the elements are arranged even on the side provided with the
curvature of the acoustic lens. It is possible to form an optimal focusing or diverging sound field
corresponding to the change of the curvature radius of.
[0071]
In any array sensor, one group of two groups of array sensors is used for ultrasonic wave
generation (also referred to as transmission) and another group is used for ultrasonic wave
reception. If there is only one group of array sensor groups, then a plurality of selected elements
in the group may be used for receiving other selected elements for ultrasonic wave generation.
[0072]
The internal structure of an ultrasonic probe 501 having an array sensor will be briefly described
using FIGS. 19 and 20. FIG. Although FIG. 19 and FIG. 20 correspond to FIG. 7 and FIG. 8
described above, the same internal structure as in FIG. 9 and FIG. 10 except only the
arrangement of the acoustic lens and the sound insulation plate.
[0073]
The array sensor 501 includes an element 502 for transmission and reception, a backing layer
1902 for appropriately limiting the oscillation time of the element, a matching layer 1903 for
adjusting transmission and reception efficiency, and an acoustic lens 103. The other parts are
accommodated in a case 1901 except that the acoustic lens 103 is exposed to the outside. These
parts are integrally coupled by bonding or screws.
[0074]
When separate array sensor groups are used for transmission of ultrasonic waves and reception
of echoes, as in FIGS. 7 to 12, the acoustic lens is provided with a sound insulation plate for
blocking the propagation of sound (described later) In order to prevent acoustic crosstalk
between the transmitting and receiving array sensors, a sound insulating plate 2001 may be
provided inside the array sensor as shown in FIG.
03-05-2019
22
[0075]
Next, the focusing effect of the acoustic lens will be described with reference to FIGS. 21A to 21C.
FIG. 21A is an explanatory diagram of the case where the ultrasonic probe 101 is a conventional
sensor (sensor not having an array structure) and an array sensor of “combination 1”. 21B and
21C are explanatory diagrams of the case of the “combination 2” array sensor.
[0076]
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 20 mm) (same as FIG. 4) and the
curvature radius slightly smaller (radius 15 mm) As in FIGS. 3 and 4, the analysis of the
ultrasonic wave propagation was shown. By making the radius of curvature of the acoustic lens
smaller than the radius of curvature of the metal surface (FIG. 21A (B)), the ultrasonic wave
transmitted from the acoustic lens to water is once diffused and then focused when it is incident
on the metal As a result, it can be confirmed that a region where ultrasonic waves are focused
reaches a deeper position 2101 than in the case where the curvature radius of the acoustic lens
is equal to the curvature radius of the metal surface (position 401 in FIG. 21A).
[0077]
In FIG. 21B, in the case where the curvature to be inspected (radius 20 mm) and the curvature
radius of the acoustic lens are close (radius 18 mm), the object to be inspected when the sound
field formed by the array sensor 2105 is changed by 3 patterns It is the result of analyzing the
focal sound field in (metal).
[0078]
By changing the delay time given to each element constituting the array sensor, it can be
confirmed that the focal distance in the metal is changed.
For example, FIG. 21B (A) shows a result in the case where a focused sound field is formed by the
03-05-2019
23
array sensor, and FIG. 21B (C) shows a result in the case where a diverging sound field is formed
by the array sensor. As compared with the position 2103 of the focus depth of the focus of the
ultrasound in the metal in the flat (unfocused) sound field of FIG. 21B (B), the superposition in
the metal when the focus sound field is set (A) It can be seen that the position 2102 of the focus
depth of the focusing of the sound wave is shallow, and the position 2104 of the focus depth of
the ultrasound focus changes in the depth when the diverging sound field is set (C). .
[0079]
By using this effect, even when the curvature radius of the metal surface to be inspected is
dispersed, the focal depth in the inspection object can be made constant by changing the sound
field formed by the array sensor 2105. Can be controlled.
[0080]
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 radius 16, 20, 25 mm, The
analysis results are shown as constant values.
The case where the curvature of the metal surface is 20 mm and the sound field by the array
sensor is flat shown in FIG. 21C (A) is considered as a reference. When the radius of curvature of
the metal surface is 25 mm (FIG. 21C (B)), the focusing effect on the metal surface also decreases
because the radius of curvature increases. Therefore, in order to focus on a depth substantially
the same as the focal depth 2106 shown in FIG. 21C (A), it is necessary to set the acoustic field
formed by the array sensor 2105 as a focused acoustic field.
[0081]
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 becomes
smaller. Therefore, in order to focus on a depth substantially the same as the focal depth 2106
shown in FIG. 21C (A), it is necessary to make the sound field formed by the array sensor 2105 a
diverging sound field.
[0082]
03-05-2019
24
As described above, in the case of “combination 2” of the array sensor arrangement and the
acoustic lens described above, variation in the radius of curvature of the metal surface to be
inspected occurs by changing the sound field formed by the array sensor. Also, the focal depth
can be kept constant at a desired value.
[0083]
Next, using FIG. 22 and FIG. 23, the case where the ultrasonic probe as described in this
embodiment is used as an inspection device for reactor internals of a nuclear power plant will be
described below.
The inspection device mast 2210 is hung from the vertical movement mechanism 2203 on the
work carriage 2202 with a wire 2205 from the work carriage 2202 on the operation floor 2201
inside the reactor building of the nuclear power plant to the reactor water 2206 in the reactor
pressure vessel. Be taken down.
[0084]
The mast 2210 lowered into the reactor water 2206 passes through the upper grid 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 mounted on the mast 2210, and an inspection head
2303 including an ultrasonic probe 101 is attached to the tip of the articulated manipulator
2302.
[0085]
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 hose 2304 from the upper part of the
mast 2210, extended to the operation floor 2201 and connected to the controller 2207 .
[0086]
The base 2305 of the manipulator 2302 is a structure attached to the mast 2210 and capable of
vertical and rotational movement.
03-05-2019
25
The manipulator 2302 is composed of a plurality of bending joints 2306 and a rotation joint
2307. At the tip of the manipulator 2302, there is a hand unit 2308, which can grip an
inspection head 2303 comprising an ultrasonic probe 101, a probe pressing mechanism 2309,
and a probe scanning mechanism 2310.
[0087]
The ultrasonic probe 101 can be moved by the scanning mechanism 2310 while following the
curved surface of the CRD stub weld by the probe pressing mechanism 2309, and ultrasonic
inspection of the crack 104 of the weld can be performed. .
[0088]
Operations such as rotation of the mast 2210, control of the articulated manipulator 2302,
inspection head 2303 (probe scanning and pressing), etc. are controlled by the inspection device
controller 2207 on the operation floor 2201, and control signals are transmitted using the signal
cable 2208 It is transmitted.
The ultrasonic probe 101 built in the inspection head 2303 is controlled (and recorded) by the
ultrasonic flaw detector 2209, and transmission and reception signals are mutually transmitted
using a signal cable 2208.
[0089]
The same configuration can be applied to the second embodiment as to the configuration
example of the inspection apparatus described in FIGS. 22 and 23.
[0090]
FIG. 13 shows a second embodiment of the present invention. As shown in the figure, an
ultrasonic probe 1301 that makes ultrasonic waves incident is pressed against an inspection
target 102 having a curved surface to perform flaw detection.
03-05-2019
26
The defects to be inspected are the same as in the first embodiment, such as the crack 104
opened on the curved surface side and the defects 106 inherent to the object to be inspected.
[0091]
The ultrasound probe 1301 is composed of a transmitting or receiving element 1302 and an
acoustic lens 1303.
[0092]
Between the inspection object 102 and the ultrasonic probe 1301, a couplant (also called
couplant) such as water or glycerin is applied or filled as an intermediate medium to improve
sound propagation. Do.
[0093]
As the acoustic lens 103, one having an intermediate characteristic between the inspection object
102 and the contact medium is used.
For example, synthetic resins such as acrylic, polystyrene, and polyimide are used.
In these materials, the propagation velocity of the longitudinal wave is from 2400 m / sec to
2900 m / sec, and the sound velocity is intermediate between the inspection object 102 and the
contact medium.
[0094]
In the second embodiment, the radius of curvature of the acoustic lens may be along the radius
of curvature of the inspection object 102. In this case, as described in the first embodiment, the
radius of curvature of the acoustic lens becomes larger than the radius of curvature which is the
optimum value, so the diffusion effect by the acoustic lens is weakened and the focusing effect on
the surface of the inspection object 102 is Overcoming, a phenomenon occurs in which the focal
point is formed at a shallow position compared to the desired depth.
03-05-2019
27
[0095]
In order to avoid this phenomenon and efficiently propagate ultrasonic waves to a deep portion
to be inspected, the element 1302 for generating and / or receiving ultrasonic waves is provided
with a convex shape. By making the element 1302 convex, the diffusion effect by the acoustic
lens and the diffusion effect by the shape of the element are added, the focusing effect by the
concave surface of the inspection object 102 is offset, and the ultrasonic wave is transmitted to
the deep part of the inspection object 102 Will be able to
[0096]
The relationship between the curvature to be imparted to the acoustic lens and the curvature to
be imparted to the element will be described with reference to FIGS. 14 and 15. FIG. In FIGS. 14
and 15, the abscissa represents the ratio of the curvature radius of the acoustic lens (R shoe) to
the curvature radius of the inspection object (R steel), and the ordinate represents the curvature
radius of the element (R element) and the inspection object The ratio of radius of curvature (R
steel) is taken. FIG. 14 shows the case where the longitudinal acoustic velocity of the acoustic
lens is 2,400 m / sec, and FIG. 15 shows the case where it is 2,900 m / sec.
[0097]
The acoustic lens having a curvature radius larger than the curvature radius of the acoustic lens,
which improves the adhesion between the curved surface to be inspected and the ultrasonic
probe or is determined as the recommended optimum value in the first embodiment When
testing concave surfaces, the value of R sensor / R steel is between about 0.6 and 1.0 which
means perfect adhesion, which corresponds to the optimum value in the first embodiment. be
able to.
[0098]
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 object under inspection decreases in order
to form a diverging sound field inside the object under inspection, and the radius of curvature of
the acoustic lens is inspected Exceeding the radius of curvature of the object is physically
difficult from the contact point of view.
[0099]
03-05-2019
28
When the value of R sensor / R steel changes 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 is about 0.6 times the curvature of the object to be inspected, and the sensor has no
curvature (flat).
Evaluating the optimal value of the curvature of the element by analytically determining the
curvature of the element when the curvature of the acoustic lens is changed, given a constraint
that can be regarded as equivalent to the diverging sound field at this time. Can.
[0100]
For example, when the ratio of the curvature of the acoustic lens to the curvature radius of the
concave surface to be inspected is about 0.6, in both FIGS. 14 and 15, the ratio of the curvature
of the element to the curvature of the surface to be inspected diverges to + ∞. Know that This
corresponds to the fact that the element is flat. As the ratio of curvature of the acoustic lens
(horizontal axis of graph) is increased gradually from 1.0 to 0.6 from 0.6, the ratio of curvature
radius of element (vertical axis of graph) gradually increases from + 徐 々 にThe curvature radius
of the element is found to be about 3 to 4 times as large as the curvature radius of the concave
surface to be inspected when the ratio of the curvature of the acoustic lens becomes 1.0 and
matches the curvature radius of the object to be inspected. .
[0101]
From this analysis result, when the acoustic lens follows the radius of curvature, by setting the
radius of curvature larger than three times the radius of curvature of the concave surface to be
inspected as the radius of curvature of the element, efficient inside the object to be inspected It
turns out that it becomes possible to inject an ultrasonic wave to the deep part.
[0102]
In the case where there is a variation in the radius of curvature of the inspection object, the
variation in the radius of curvature of the element and the acoustic lens is determined based on
the smallest possible radius of curvature from the viewpoint of contactability to cope with the
03-05-2019
29
variation. Is possible.
[0103]
Also in the second embodiment, as in the first embodiment, the element constituting the array
sensor is one-dimensional or two-dimensional as the element 105 for ultrasonic wave generation
and / or reception constituting the ultrasonic probe. Can be placed.
[0104]
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.
The combination 1 is when the element array direction is parallel to the axial direction of the
acoustic lens, and the combination 2 is when the element array direction is orthogonal to the
axial direction of the acoustic lens.
[0105]
In the case of combination 1, since the direction of the elements constituting the array sensor is
the axial direction of the acoustic lens, the acoustic field by the array sensor has a curvature of
the acoustic lens regardless of the delay time pattern given to each element. It will be affected
only by the radius.
For this reason, only one element is represented on a cross-sectional view perpendicular to the
axial direction of the acoustic lens, and is displayed as shown in FIG.
For this reason, the description (Fig. 13, Fig. 14, Fig. 15) of a normal sensor (sensor not having
an array structure) and the description of the "combination 1" array sensor can be regarded as
common.
[0106]
03-05-2019
30
On the other hand, in the case of combination 2, the curvature of the acoustic lens is attached in
the direction of the array of elements of the array sensor, so the sound field by the array sensor
changes according to the pattern of delay time given to each element. For this reason, only one
element is represented on a cross-sectional view perpendicular to the axial direction of the
acoustic lens, and is displayed as shown in FIG.
[0107]
FIG. 16 shows an example in which the elements are one-dimensionally arranged in the 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 and / or reception element 105 constituting the
ultrasonic probe, as shown in FIG. By changing the timing (delay time) at which the light is
generated, it is possible to form various sound fields with different degrees of flat, focusing, and
divergence, and focusing or according to the change of the curvature radius of the concave
surface to be inspected The diverging sound field can be synthesized electronically.
[0108]
Further, in the ultrasonic probe according to the second embodiment, in order to cope with the
change of the curvature radius of the inspection object, an array sensor for the acoustic lens
(1603 or 1604) having a different curvature radius with respect to the acoustic lens 1303 By
making the element group 1605 forming the element in common, and using the array sensor in
contact with acoustic lenses having different curvatures, ultrasonic probes corresponding to a
large number of curvature radii can be obtained.
[0109]
Here, the structure of the element of the array sensor to be in contact with the acoustic lens
having a different curvature will be described with reference to FIGS. 17 and 18.
FIG. 17 shows the case where the elements are arrayed one-dimensionally, and FIG. 18 shows the
case where the elements are arrayed two-dimensionally. In any case, when the element is
brought into contact with a concave surface (1703 in FIG. 17), the difference in the curvature of
the element causes a difference in the amount of deflection, which may cause breakage or
03-05-2019
31
disconnection of the element. Ru.
[0110]
Therefore, regarding the elements (1701 in FIG. 17 and 1801 in FIG. 18) constituting the array
sensor to be in close contact with the concave surface, a notch is provided in each element to
make the cross-sectional shape trapezoidal. It is possible to improve the quality.
[0111]
A manufacturing procedure in the case of arranging elements one-dimensionally as shown in FIG.
17 will be described with reference to FIGS. 24 (A to C).
First, ultrasonic elements are placed at appropriate intervals, and synthetic resin is poured
around them to manufacture a sheet-like ultrasonic element for flexible array (FIG. 24A). Next,
the element is incised to have a one-dimensional arrangement (FIG. 24B) and completed (FIG.
24C).
[0112]
A manufacturing procedure in the case of arranging elements two-dimensionally as shown in FIG.
18 will be described with reference to FIGS. 25 (A to C). First, the ultrasonic element is placed in
a mold in which the final two-dimensionally arranged trapezoidal shape part is cut out (FIG. 25A).
Next, the synthetic resin is poured into the mold (FIG. 25B), removed from the mold and
completed (FIG. 25C).
[0113]
The ultrasonic probe according to the second embodiment is also controlled (and recorded) by
the ultrasonic flaw detector 2209 as in the first embodiment, and transmission and reception
signals are mutually transmitted using the signal cable 2208. It has become.
[0114]
The present invention is adopted in an ultrasonic probe used in connection with an ultrasonic
flaw detector to perform nondestructive inspection using ultrasonic waves.
03-05-2019
32
[0115]
It is a conceptual diagram in flaw detection operation of the ultrasonic probe concerning a 1st
example of the present invention.
It is a graph figure regarding the optimal value factor of the acoustic lens used for the example of
the present invention.
It is explanatory drawing showing the focusing effect of the ultrasonic wave by the concave
surface of the surface to be examined by a prior art example. It is another explanatory view
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 ultrasound probe by the Example of this invention, the concave curve to be
examined, and an acoustic lens. It is explanatory drawing which showed the other relationship
with the array element in the ultrasound probe by the Example of this invention, the concave
curve to be examined, and an acoustic lens. An example of each sound field according to the
relationship between the position of each element from the one end in the arrangement direction
of the array elements in the embodiment of the present invention (when 24 elements are arrayed
and adopted at 1 mm pitch) and the delay time of ultrasonic wave generation And the figure
which visualized and showed the propagation of the ultrasonic wave in each sound field. It is a
figure showing arrangement of an element of an array sensor which can be adopted as an
example of the present invention, and arrangement of an acoustic lens etc. FIG. 7 is a view
showing another arrangement of elements of an array sensor that can be adopted in the
embodiment of the present invention, and an arrangement of acoustic lenses and the like. It is the
figure which showed the arrangement | positioning of the further another arrangement |
positioning of the element of the array sensor which can be employ | adopted as the Example of
this invention, an acoustic lens etc. FIG. 6 is a diagram showing still another arrangement of
elements of an array sensor and an acoustic lens etc. which can be adopted in the embodiment of
the present invention. It is a figure showing arrangement of elements of an array sensor which
can be adopted in an embodiment of the present invention in both orthogonal directions and
arrangement of an acoustic lens and the like. FIG. 7 is a view showing another arrangement of
elements of the array sensor which can be employed in the embodiment of the present invention
and arrangement of an acoustic lens or the like in both orthogonal directions. It is a conceptual
diagram in flaw detection operation of the ultrasonic probe concerning a 2nd example of the
present invention. It is a figure explaining the relation of the curvature of the shoe of an
ultrasonic probe, and a sensor in a 2nd example of the present invention. It is a figure explaining
03-05-2019
33
the relationship between the shoe of an ultrasonic probe, and the curvature of a sensor in the
condition where the sound velocity of the acoustic lens in 2nd Example of this invention differs
from the case of FIG. It is an explanatory view explaining adjustment of a sound field of an
ultrasonic wave in a 2nd example of the present invention. It is explanatory drawing of the
element which has a trapezoid cross section which can be employ | adopted by 2nd Example of
this invention. It is explanatory drawing of the element which is a trapezoid in the cross section
of two orthogonal directions employable by the 2nd Example of this invention. It is sectional
drawing which shows an example of the internal structure of the ultrasound probe in the
Example of this invention. It is sectional drawing which shows another example of the internal
structure of the ultrasound probe in the Example of this invention. It is explanatory drawing
showing the change of the depth of the focusing position of the ultrasonic wave which changes
with the relationship of the curvature of the acoustic lens of an ultrasound probe, and the
curvature of the curved surface to be examined. It is explanatory drawing showing the change of
the depth of the focusing 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 focusing position of the
ultrasonic wave corresponding to the change of the curvature radius of the acoustic lens of an
ultrasonic probe. It is a longitudinal cross-sectional view of the reactor pressure vessel and its
periphery part which showed the condition which is performing the inspection operation | work
with the reactor in-vessel inspection apparatus using the ultrasonic probe of this invention. It is a
principal part enlarged view of FIG. FIG. 18 is an explanatory view showing the first half of the
manufacturing process of the ultrasonic element having a trapezoidal cross section which can be
adopted in the second embodiment of the present invention; It is explanatory drawing which
shows the condition of the middle stage in the manufacture process of the ultrasonic element
which can be employ | adopted by the 2nd Example in this invention of a trapezoid. It is
explanatory drawing which shows the last stage of the manufacture process of the ultrasonic
element which can be employ | adopted by 2nd Example in this invention of a trapezoid cross
section. It is explanatory drawing which shows the first half of the manufacture process of the
ultrasonic element which the cross section of the orthogonal 2 direction which can be employ |
adopted in the 2nd Example in this invention has a trapezoid. It is explanatory drawing which
shows the middle of the manufacture process of the ultrasonic element of the cross section of the
orthogonal 2 direction which can be employ | adopted in the 2nd Example in this invention of a
trapezoid. It is explanatory drawing which shows the last stage of the manufacture process of the
ultrasonic element of the orthogonal two-direction cross section which can be employ | adopted
in the 2nd Example in this invention of a trapezoid. The explanatory view showing the
combination of the arrangement of the array sensor and the acoustic lens in the present
invention shows an example in which the axial direction of the acoustic lens coincides with the
arrangement direction of the elements of the array sensor. The explanatory view showing the
combination of the arrangement of the array sensor and the acoustic lens in the present
03-05-2019
34
invention shows an example in which the axial direction of the acoustic lens is orthogonal to the
arrangement direction of the elements of the array sensor.
Explanation of sign
[0116]
101 ... ultrasonic probe, 102 ... inspection object, 103 ... acoustic lens, 104 ... crack, 105 ...
element for ultrasonic wave generation and / or reception, 106 ... defect.
03-05-2019
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