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DESCRIPTION JPH1082769

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DESCRIPTION JPH1082769
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
probe used in an ultrasonic flaw detector.
[0002]
2. Description of the Related Art The prior art is shown in FIGS. FIG. 3 is a cross-sectional view
showing a flaw detection situation for the attachment welding portion 21 of the conventional
small-diameter nozzle 1.
[0003]
FIG. 4 is a cross-sectional view showing the propagation condition of the ultrasonic beam at the
time of flaw detection, targeting the attachment welding portion 21 of the conventional smalldiameter nozzle 1. As a nondestructive inspection method for the pressure vessel 20 and the like,
there is a method using ultrasonic waves.
[0004]
In principle, it consists of an ultrasonic flaw detector, a probe, etc., and the ultrasonic wave
generated by the probe is made to enter the inspection material such as a pressure vessel and
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propagate it, and the reflection signal is detected. It is intended to detect the presence of a crack
or the like inside the test material flaw detector.
[0005]
At this time, the probe has a role of transmitting and receiving ultrasonic waves.
FIG. 3 shows the shape of the attachment weld portion 21 of the small diameter nozzle 1
installed in the pressure vessel 20 and the appearance of flaw detection.
[0006]
The target area of inspection is the weld and its surroundings. The flaw detection is performed
using a flaw detection device including a probe guide operation device (not shown), a flaw
detector (not shown), the probe 4 and the like.
[0007]
In FIG. 3, the probe 4 is inserted into the inside of the nozzle 1 which is a material to be
inspected to try to detect the portion. The ultrasonic waves transmitted from the probe 4
propagate to the test material through the propagation medium.
[0008]
In addition, when there is a defect such as a crack inside the material to be inspected, the
ultrasonic wave is reflected by the defect, and the ultrasonic wave propagates in the reverse path,
is received by the probe, and is connected to the ultrasonic flaw detector The defect detection
signal is detected as a defect signal on the flaw detection signal waveform signal.
[0009]
At this time, if a probe having a planar transducer generally used is used, the ultrasonic wave is
refracted and the ultrasonic wave is focused near the surface under the influence of the
curvature of the surface of the test material. I will.
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[0010]
FIG. 4 (a) shows such an aspect, and the focusing position 22 of the ultrasonic wave is
determined by the sound speed and shape of the component, and the ultrasonic wave diffuses in
the distance from the focusing position.
Due to the diffusion of the ultrasonic waves, the density of the ultrasonic waves is reduced in the
flaw detection area, and the reflection signal from the defect is also reduced, leading to a
decrease in detection performance.
[0011]
In order to prevent the influence of the curvature of the surface of the material to be inspected
and to make the ultrasonic wave properly incident on the flaw detection area in the depth
direction, as shown in an example of FIG. An acoustic lens is attached and used for the purpose of
diffusing ultrasonic waves on the front surface of a probe having a wave-like transducer.
[0012]
However, even in this case, the focusing position of the ultrasonic wave is determined by the
speed of sound and shape of the component, that is, the speed of sound of the ultrasonic wave
propagation medium, the speed of sound and curvature of the acoustic lens material, and the
speed of sound and curvature of the test material In the same manner as described above, the
curvature condition of the convex transducer in which the ultrasonic wave is focused in the flaw
detection area or the sound velocity and curvature condition of the acoustic lens are set in
advance and used.
[0013]
These conditions are conditions for focusing to a certain depth position in the test material, and
in order to flawlessly scan the entire area in the depth direction flaw detection region, a plurality
of probes with different focusing regions are required. And, according to the focusing area of the
ultrasonic wave, it uses properly and performs flaw detection.
[0014]
As a method of propagating ultrasonic waves generated by the probe 4 to the test material, a
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water immersion method in which water is filled as a propagation medium in an ultrasonic wave
propagation path between the probe and the test material and a flaw is detected. There is a direct
contact method in which a flaw is detected by bringing the tip into contact with the test material
directly.
[0015]
For these methods, dedicated probes are used. In particular, in the direct contact method, a shoe
having a shape that matches the surface curvature of the test material made of an acrylic resin
material or the like as a propagation medium is fronted. The probe set in the above is used in
combination with the above-mentioned convex transducer and an acoustic lens for diffusing
ultrasonic waves.
[0016]
However, the above conventional probe has the following problems.
(1) Since the focusing position of ultrasonic waves is constant and the focusing area available for
flaw detection is limited, only a part of the inspection area in the depth direction around the weld
can be flawed .
(2) In order to flawlessly inspect the inspection range in the depth direction, a plurality of probes
with different focusing positions are required.
(3) In addition, convex transducers require advanced manufacturing techniques and become
expensive as compared with planar transducers.
An object of the present invention is to provide a probe that can solve these problems.
[0017]
[Means for Solving the Problems] (First Means) In a variable focusing probe according to the
present invention, in a probe used for an ultrasonic flaw detector, (A) a flat transducer is used.
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And (B) an acoustic lens (5) disposed on the side of the inspection material of the probe 4 for
performing convergence and diffusion of ultrasonic waves, and (C) movement adjustment of the
acoustic lens It consisted of mechanism (6, 7), (D) probe holder (3), and (E) casing (10), and kept
the distance between the (F) probe (4) and the test material constant It is characterized in that
the movement of the acoustic lens (5) can be adjusted in the state.
(Second Means) In the variable focusing probe according to the present invention, in the probe
used for the ultrasonic flaw detector according to the second means, the casing (10) is attached
to the surface of the test material. It is characterized by having the same curvature shape.
[0018]
Therefore, it works as follows.
Since the variable focusing probe according to the present invention is configured as described
above, (1) at the time of flaw detection, the acoustic lens 5 can be moved by operating the
position adjustment screw 7, and the inside of the test material is The position at which the
ultrasonic waves are focused can be adjusted to an arbitrary position. (2) In addition, since the
position of the acoustic lens 5 can be moved and adjusted while keeping the distance between
the probe 4 and the inspection material constant, the defect signal position on the flaw detection
waveform does not change and is maintained at a constant position. Will be
[0019]
DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of
the present invention is shown in FIGS. FIG. 1 is a cross-sectional view of a variable focusing
probe according to a first embodiment of the present invention.
[0020]
FIG. 2 is a cross-sectional view showing the appearance of an ultrasonic beam of the variable
focusing probe according to the first embodiment of the present invention. FIG. 1 shows an
example of a state in which the variable focusing probe according to the present invention is
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installed on the inner surface of the small diameter nozzle 1 to be inspected, and the variable
focusing probe main body 2 is a probe A holder 3 and a probe 4 are attached, and an acoustic
lens 5 having a variable distance to the front surface of the probe is installed on the front surface
of the probe 4 and a variable focusing type probe main body 2 is a spring It is positioned by 6
and adjusting screw 7.
[0021]
The acoustic lens 5 is structured such that its position can be moved by the operation of the
adjusting screw 7. FIG. 2 shows the aspect of propagation of an ultrasonic beam by installing the
present invention in a small diameter nozzle to be inspected, and FIG. 2 (a) shows the distance
between the front surface of the probe and the acoustic lens 5 The adjustment screw 7 is
adjusted to adjust the focus 9 of the ultrasonic beam 8 to a short distance in the inspection
object. FIG. 2 (b) similarly shows a state in which the focus of the ultrasonic beam is adjusted to a
long distance in the inspection object.
[0022]
Since the present invention is configured as described above, the following effects can be
obtained. (1) According to the present invention, when a probe is inserted inside a nozzle such as
a small diameter nozzle and the like in order to detect a flaw in the vicinity of a weld, a position
where ultrasonic waves suitable for flaw detection are focused It can be easily adjusted to any
position. Therefore, it can contribute to the improvement of defect detection performance. (2) In
addition, since the position of the acoustic lens can be moved and adjusted while keeping the
distance between the probe and the inspection material constant, the defect signal position on
the flaw detection waveform can be kept constant without changing. Become. (3) Therefore, it is
not necessary to possess a plurality of probes or to replace probes according to a flaw detection
area, and efficient flaw detection can be realized.
[0023]
Brief description of the drawings
[0024]
1 is a cross-sectional view of a variable focusing probe according to a first embodiment of the
present invention.
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[0025]
2 is a cross-sectional view showing the appearance of the ultrasonic beam of the variable
focusing probe according to the first embodiment of the present invention.
[0026]
3 is a cross-sectional view showing a flaw detection situation for a conventional small diameter
nozzle attachment weld portion.
[0027]
4 is a cross-sectional view showing the propagation state of the ultrasonic beam at the time of
flaw detection for the conventional small-diameter nozzle attachment weld portion.
[0028]
Explanation of sign
[0029]
DESCRIPTION OF SYMBOLS 1 small diameter nozzle 2 variable focusing type probe main body 3
probe holder 4 probe 5 acoustic lens 6 spring 7 adjustment screw 8 ultrasonic beam 9 focus 10
casing 20 pressure vessel 21 ... Mounting weld 22 ... Focused position
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