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DESCRIPTION JP2001289625
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic sensor for measuring the thickness, flaws and the like of a specific layer of a sample by
ultrasonic waves, and in particular, an acoustic lens is defined by a coupling liquid in contact with
an ultrasonic transducer. In addition, the present invention relates to a contact type ultrasonic
sensor with a delay material provided with a delay material that contacts the specimen to receive
an ultrasonic wave incident on the specimen and a reflected wave from the specimen.
[0002]
2. Description of the Related Art Ultrasonic waves differ in propagation velocity (sound velocity)
depending on the density of a propagating medium, and have the property of being reflected at
the boundary between media of different densities. Therefore, if there is an air layer between the
test piece and the ultrasonic transducer, the ultrasonic wave is reflected at the boundary between
the air layer and the test piece and the ultrasonic wave can not be made to enter inside the test
piece. Conventionally, a contact-type ultrasonic sensor with a delay material has been known that
is equipped with a delay material that contacts the specimen to receive the ultrasonic wave
incident on the specimen and the reflected wave from the specimen. In a sound wave sensor, a
coupling liquid is usually filled between the delay material and the ultrasonic transducer, and a
concave surface is formed on the end surface of the delay material facing the ultrasonic
transducer, and the concave surface is ultrasonic vibration with that An acoustic lens is defined
by the coupling liquid in contact with the child, and the acoustic lens focuses the ultrasonic wave
generated from the ultrasonic transducer at a predetermined focal point.
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[0003]
However, since the focal point of the ultrasonic wave is set in the delay material in the
conventional ordinary contact ultrasonic sensor with delay material, diffuse reflection of the
ultrasonic wave is generated in the delay material, and thus the delayed reflected wave is
detected. There is a problem that it can not be used for a thin specimen because the dead time is
set so as not to be used. Therefore, the applicant of the present invention solves the abovementioned problems by setting the height of the delay material so that the focal point of the
ultrasonic wave is located outside the delay material, that is, in the test body in JP-A-8-247751.
Disclosed a contact type ultrasonic sensor with delay material.
[0004]
By the way, when the inventor of the present invention studied the above-mentioned
conventional contact ultrasonic sensor with delay material, in the contact ultrasonic sensor with
delay material, the delay material on the propagation path of the ultrasonic wave is obtained. In
addition to the boundary between the sensor and the specimen, there is also a boundary between
the delay material and the coupling fluid inside the sensor, so reflected waves at those
boundaries are also detected, so the signal / noise (S / N) ratio It turned out that there is a
disadvantage of being bad. And this is, for example, the boundary between the remelt
reinforcement layer (layer obtained by densifying the crystal grains by remelting) formed on the
surface of the cast parts such as the cylinder head of the engine and the ordinary crystal grain
part at the back thereof When it detects the scattered wave from the boundary inside the test
body as a reflected wave, it is particularly problematic because it is weaker than the reflected
wave from the bottom of the test body that was conventionally detected, and it detects if the
sensor output is not amplified more On the other hand, when the amplification degree is
increased, the noise is also increased and the detection of the scattered wave is disturbed.
Therefore, as a result of further researches by the inventor of the present invention, it is possible
to clearly detect even weak scattered waves by improving the setting of the rotating body shape
of the acoustic lens and the setting of the heights of the delay material and the coupling liquid. I
thought about the point.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the abovementioned point, and the contact type ultrasonic sensor with delay material of the present
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invention according to claim 1 is an ultrasonic wave. A delay material comprising a delay
material for forming an acoustic lens with a coupling liquid in contact with a transducer and for
contacting with a test object to cause incidence of an ultrasonic wave to the test product and
reception of a reflected wave from the test product In the attached contact type ultrasonic
sensor, a return position where an ultrasonic wave generated from a predetermined generation
position on the vibration surface of the ultrasonic transducer is reflected at a predetermined
focal position in the test body, and a center point of the vibration surface The rotating body of
the acoustic lens has a shape in which the value obtained by calculating the distance between the
generation position and the symmetrical position while moving the predetermined generation
position from the center point of the vibration surface to the outer peripheral end is minimum.
Shape is And it is characterized in that it is a constant.
[0006]
In general, in an ultrasonic transducer, if the generation position and the return position of the
ultrasonic wave are point-symmetrical with respect to the center of the vibrating surface, it is
said that the reflected wave can be most efficiently detected. In the sound wave sensor, the radius
of the spherical surface of the acoustic lens is set so that the ultrasonic wave generated from one
outer peripheral end of the vibrating surface is reflected at the focal position in the test body and
returned to the opposite outer peripheral end. In the setting, it was not possible to efficiently
detect the reflected wave on the entire vibration surface.
On the other hand, according to the ultrasonic sensor of the present invention described above,
the shape of the rotating body of the acoustic lens is set to a shape that minimizes the error of
symmetry between the generation position and the return position of the ultrasonic wave as the
entire vibration surface of the ultrasonic transducer Therefore, the reflected wave from the focal
position can be detected most efficiently on the vibration plane.
[0007]
Therefore, according to this ultrasonic sensor, the scattered wave from the boundary near the
focal position in the test body can be clearly detected without increasing the amplification degree
of the sensor output so much that the boundary in the test body is S It is possible to perform
highly accurate detection with a good / N ratio.
[0008]
In the contact ultrasonic sensor with delay material according to the second aspect of the present
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invention, the acoustic lens is defined by the coupling liquid in contact with the ultrasonic
transducer, and the ultrasonic wave to the sample is brought into contact with the sample. In a
contact type ultrasonic sensor with a delay material provided with a delay material for
performing incidence of incident light and reception of a reflected wave from the sample, the
delay material and the sample of an ultrasonic wave generated from the ultrasonic transducer
Between the plurality of longitudinal wave reflections resulting sequentially from the boundary
between the delay material and the coupling fluid and / or simultaneously with the longitudinal
wave reflections of the ultrasonic waves, As the shear wave reflected wave from the boundary
between the delay material and the sample ends, the longitudinal wave reflected wave one before
or at the same time as the longitudinal wave reflected wave one before or after the fall of the
transverse wave reflected wave In the meantime, the super sound The height of the acoustic lens
and the height of the delay material are set to a dimension at which the longitudinal wave
reflected wave from the boundary of the depth within a predetermined measurement range from
the surface of the specimen returns. It is
[0009]
In such an ultrasonic sensor, the ultrasonic wave generated from the ultrasonic transducer is
transmitted from the boundary between the delay material and the specimen, one time before the
end of the reflected wave whose propagation speed is slower than that of the longitudinal wave.
Or between the longitudinal wave reflections from the boundary between the delay material and
the test piece and the boundary between the delay material and the coupling liquid, of the same
and the immediately preceding one, Since the heights of the acoustic lens and the delay material
are set so that the longitudinal waves reflected from the boundary of the depth within the
predetermined measurement range from the surface of the test object result from ultrasonic
waves, from the surface of the test object Longitudinal wave reflection waves from the boundary
of depth within the predetermined measurement range are sequentially reflected longitudinal
waves from the boundary between the delay material and the specimen and the boundary
between the delay material and the coupling liquid. Also, the reflected wave from the boundary
between the delay material and the specimen It is detected without overlapping as well.
[0010]
Therefore, according to this ultrasonic sensor, even weak scattered waves from the boundary of
the depth within the predetermined measurement range from the surface of the specimen can be
clearly detected, and highly accurate detection with good S / N ratio Can.
[0011]
On the other hand, in the contact ultrasonic sensor with delay material according to the third
aspect of the present invention, the acoustic lens is defined by the coupling liquid in contact with
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the ultrasonic transducer, and the ultrasonic wave to the specimen is contacted with the
specimen. In a contact type ultrasonic sensor with a delay material provided with a delay
material for performing incidence of incident light and reception of a reflected wave from the
sample, the delay material and the sample of an ultrasonic wave generated from the ultrasonic
transducer Between the plurality of longitudinal wave reflections resulting in successive
reductions from the boundary between the delay material and the boundary between the delay
material and the coupling liquid; A predetermined range of measurement of the ultrasonic wave
from the surface of the specimen between the longitudinal wave reflected wave and the
transverse wave reflected wave immediately before the transverse wave reflected wave comes
back as well as the transverse wave reflected wave from the boundary comes back From the
inner depth boundary It is characterized in that the wave reflected wave height and the height of
the delay member of the acoustic lens to the dimensions that result is set.
[0012]
In such an ultrasonic sensor, longitudinal waves resulting from the boundary between the delay
material and the specimen and the boundary between the delay material and the coupling liquid
sequentially occur in the ultrasonic wave generated from the ultrasonic transducer. A transverse
wave reflected wave from the boundary between the delay material and the specimen which
results in a reflection between waves, and whose longitudinal velocity is slower than that of the
longitudinal wave, and the longitudinal wave reflected before the one resulting from the
transverse wave reflected wave Since the heights of the acoustic lens and the delay material are
set so that the longitudinal wave reflected from the boundary of the depth within the
predetermined measurement range from the surface of the specimen is obtained between
Longitudinal wave reflection waves from the boundary of the depth within a predetermined
measurement range from the surface of the test specimen are successively reduced from the
boundary between the delay material and the test specimen and the boundary between the delay
material and the coupling liquid Or the boundary between the delay material and the specimen It
is detected without overlapping the even transverse the reflected wave.
[0013]
Therefore, according to this ultrasonic sensor, even weak scattered waves from the boundary of
the depth within the predetermined measurement range from the surface of the specimen can be
clearly detected, and highly accurate detection with good S / N ratio Can.
[0014]
In the contact-type ultrasonic sensor with delay material according to the fourth aspect of the
present invention, an acoustic lens is defined by a coupling liquid in contact with the ultrasonic
transducer, and an ultrasonic wave to the sample is brought into contact with the sample. And a
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holder for holding the ultrasonic transducer, the acoustic lens, and the delay material in a
contact-type ultrasonic sensor with a delay material including a delay material that performs
incidence of light and reception of a reflected wave from the specimen. And a holder rotation
mechanism for rotating the holder about a predetermined axis.
[0015]
In the contact type ultrasonic sensor with delay material, since the acoustic lens is defined by the
ultrasonic transducer and the delay material, in general, their central axes are mutually separated
by the placement error between the ultrasonic transducer and the delay material. The ultrasonic
waves are emitted in a direction that is not coincident, but at a slight angle, and thus at a slight
angle to the central axis of the delay material.
In view of this point, in the ultrasonic sensor according to the present invention, the holder
rotation mechanism rotates the holder holding the ultrasonic transducer, the acoustic lens and
the delay member around a predetermined axis.
[0016]
Therefore, according to the ultrasonic sensor of the present invention, by disposing the
ultrasonic sensor in the direction in which the rotation axis intersects the surface of the sample,
the point on the sample intersecting the rotation axis is annularly formed. It is possible to scan
with ultrasonic waves, which makes it possible to detect the change in depth of the boundary
within a certain range centered on the rotation axis.
[0017]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present
invention will be described in detail by way of examples with reference to the drawings.
Here, FIG. 1 is a block diagram showing one embodiment of the contact type ultrasonic sensor
with delay material of the present invention, and the ultrasonic sensor of this embodiment is a
disk-shaped ordinary ultrasonic transducer 1; Inverted frustoconical ordinary delay material 3 in
contact with the surface of the specimen 2 at the tip end surface (lower end surface in the
figure), and between the ultrasonic transducer 1 and the delay material 3 for their super The
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spacer 4 for setting the distance between the ultrasonic transducer 1 and the delay material 3
and the space between the ultrasonic transducer 1 and the delay material 3 are filled and in
contact with the ultrasonic transducer 1 and the delay material 3 And an acoustic lens 5 formed
of a coupling liquid, wherein the delay member 3 has a convex spherical surface with a radius of
curvature R of the acoustic lens 5 by the concave spherical rear end surface (upper surface in the
figure) 3a. It is composed.
[0018]
In the ultrasonic sensor of this embodiment, as indicated by an arrow A in FIG. 1, the ultrasonic
wave generated from, for example, point P1 of the vibrating surface 1a of the ultrasonic
transducer 1 is refracted by the acoustic lens 5 For example, a remelt reinforced layer of a cast
part and a normal crystal grain in the back thereof at a position of depth FP from the surface of
the specimen 2 through the delay material 3 and further from the surface of the specimen 2 into
the specimen 2 It is reflected as a scattered wave at the boundary such as a boundary with a part,
passes through the delay member 3 again, and is refracted by the acoustic lens 5 to be reduced
to, for example, a point P2 of the vibrating surface 1a and detected by the ultrasonic transducer
1.
[0019]
By the way, in the conventional contact ultrasonic sensor with delay material, the radius of
curvature R of the acoustic lens 5 reflects the ultrasonic wave generated from one outer
peripheral end of the vibrating surface 1a at the predetermined focal position set in the specimen
2 Then, it is set to return to the outer peripheral edge (point-symmetrical with respect to the
center point O of the vibration surface 1a) on the opposite side of the vibration surface 1a
(inversely speaking, the focal position is based on the outer peripheral edge of the vibration
surface 1a In such a setting, as shown in FIG. 1, when the ultrasonic wave generated at a position
inside the outer peripheral end of the vibrating surface 1a is reflected at the focal position, a
point relative to the center point O of the vibrating surface 1a Even if the radius of curvature R is
set so that the focal position is in the vicinity of the boundary to be measured, the reflected wave
can not be efficiently detected for the entire vibration surface 1a because the reflection does not
return to the symmetrical position.
[0020]
Therefore, in the ultrasonic sensor of the above embodiment, the curvature radius R of the
acoustic lens 5 is as described below for the symmetry between the generation position and the
return position of the ultrasonic wave as a whole of the vibration surface 1a of the ultrasonic
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transducer 1. The shape is set with the least error.
That is, in this embodiment, since the surface of the acoustic lens 5 on the specimen side is a
spherical surface having a radius of curvature R, as schematically shown in FIG. 2, the radius of
the ultrasonic transducer 1 with the y axis as the central axis r, the radius of a certain ultrasonic
wave generation point is r0, the y coordinate of the central point of the spherical surface of the
acoustic lens 5 is -R, and the incident angle of ultrasonic waves on the spherical surface of the
acoustic lens 5 is θ1, from the spherical surface The emission angle is θ2, the incident angle
into the test body is θ3, the height of the acoustic lens 5 is S, the height of the delay member 3
is H, and the depth of the focal position in the test object 2 is FP. Assuming that the acoustic
velocity in the acoustic lens 5 of the longitudinal wave of the acoustic wave is VLC, the acoustic
velocity in the delay member 3 is VLD, and the acoustic velocity in the sample 2 is VLM, and C is
a coefficient, the ultrasonic wave path is symmetrical with respect to the y axis In the case, the
following relational expression of [Equation 1] holds.
However, the equations (2) and (3) depend on Snell's law.
[0022]
In the above relation, the heights S, H, the velocity of sound VLC, VLD, VLM and the radius r are
basically constants.
Therefore, if the desired focal position depth FP is set, the radius r0 at which the symmetry is
established with respect to the curvature radius R is determined, and the coefficient C is
determined therefrom.
Here, when the radius ra of the ultrasonic wave generation point is changed from the above r0,
since the acoustic lens 5 is a spherical surface, the reflected wave reflected at the boundary of
the depth FP is its ultrasonic wave on the vibrating surface 1a with respect to the y axis It does
not return to the point of symmetry with the point of origin, but is offset from that point of
symmetry.
The position shift amount is obtained while changing the position of the ultrasonic wave
generation point from ra = 0 to ra = r, and an integral value (integrated value) of the position
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shift amount is obtained. As a result, the radius r0 at which the symmetry is established is
examined while changing it, and the radius r0 at which the symmetry is established when the
integral value becomes minimum, that is, when the positional displacement amount is smallest
for the entire vibrating surface 1a is determined. The optimum value of the coefficient C is
determined from r0.
[0023]
The optimum value of this coefficient C varies depending on the depth FP of the focal position,
but in the range of the normal measurement depth with an ultrasonic sensor, it is 0.65 ≦ C ≦
0.85, and it is obtained by calculating back from the range of the value of C The radius of
curvature R of the acoustic lens is the sound velocity VLC = 1516 m / sec in the acoustic lens 5
(coupling liquid), the sound velocity VLD = 2330 m / sec in the delay member 3 (synthetic resin),
and the specimen 2 (remelt of aluminum alloy casting In the case where the sound velocity VLM
in the reinforcing layer is 6544 m / sec, the result is as shown in FIGS.
Here, FIGS. 3 to 5 show cases in which the depth FP of the focal position is adjusted to the
maximum depth of the measurable range, and FIGS. 6 and 7 show the depth of 1/2 of the
measurable range. This is the case where the depth of focus position FP is matched.
[0024]
FIG. 8 exemplifies the relationship between the change of the integrated value of the positional
displacement amount when the radius r0 at which the symmetry is established is changed and
the intensity of the first reflected wave of the ultrasonic wave, as shown in the figure. The
reflected wave intensity is maximum when the integrated value is minimum.
Further, FIGS. 9A and 9B show the reflected wave WS from the surface of the test object detected
by the conventional ultrasonic sensor and the ultrasonic sensor of the above embodiment and the
scattered wave WB from the boundary in the test body. As shown in the figure, the scattered
wave WB is clearly detected in the ultrasonic sensor of the above embodiment.
[0025]
Therefore, according to the ultrasonic sensor of this embodiment in which the curvature radius R
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of the spherical surface of the acoustic lens 5 is set as described above, the reflected wave from
the focal position can be most efficiently detected by the vibrating surface 1a. Since the scattered
wave from the boundary 2a near the focal position in the specimen 2 can be clearly detected
without increasing the amplification of the sensor output so much, the depth of the boundary 2a
in the specimen 2 It is possible to perform highly accurate detection with a good S / N ratio.
[0026]
Although the acoustic lens 5 has a spherical surface in the above embodiment, the integration
value of the positional deviation from the symmetry point is also minimized in the same manner
when the acoustic lens 5 has an ellipsoid of revolution. By obtaining the case, it is possible to
obtain shape parameters such as the major axis and the minor axis of the spheroid surface that
can most efficiently detect the reflected wave from the focal position on the vibrating surface.
[0027]
FIG. 10 is an explanatory view schematically showing the propagation state of ultrasonic waves
in the ultrasonic sensor of the above embodiment, and the surface of the acoustic lens 5 is drawn
flat for convenience of explanation.
Further, in the ultrasonic wave path, a solid line indicates a longitudinal wave, and a broken line
indicates a transverse wave.
As illustrated, when an ultrasonic wave generated at, for example, point P1 on the vibration
surface 1a of the ultrasonic transducer 1 is reflected at a point R1 on the boundary between the
acoustic lens 5 and the delay member 3, it vibrates as a longitudinal wave reflected wave LW1.
After returning to the point P2 on the surface 1a, the longitudinal wave reflected wave LW1 is
repeatedly reflected on both surfaces of the acoustic lens 5, that is, the points on the vibrating
surface 1a and the points R2 and R3 on the delay member 3 to longitudinal wave reflection. The
waves LW2 and LW3 sequentially return to points P3 and P4 on the vibrating surface 1a.
When the ultrasonic wave is reflected at a point R4 on the boundary between the delay member
3 and the surface of the test sample 2, it falls back to the point P2 as a longitudinal wave
reflected wave LW4, and the necessary measurement depth range D in the test sample 2 is
further reduced. When the light is reflected at a point R5 on the boundary 2a located at the end
of the wave, the wave returns to a point P2 after the longitudinal wave reflected wave LW4 as a
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longitudinal wave reflected wave LW5.
Furthermore, when the ultrasonic wave is reflected at a point R4 on the boundary between the
delay member 3 and the surface of the sample 2, the incident angle is large and thus it becomes
a transverse wave reflected wave TW, and the transverse wave reflected wave TW is also the
vibrating surface 1a. Return to upper point P2.
[0028]
By the way, in the conventional contact-type ultrasonic sensor with delay material, since the
timing of the return of the longitudinal wave reflected waves LW1 to LW5 and the transverse
wave reflected wave TW is not adjusted, it corresponds to the depth of the boundary 2a to be
detected. Then, other reflected waves are also returned near the timing when the longitudinal
wave reflected wave LW5 from the boundary 2a is returned, and the longitudinal wave reflected
wave LW5 to be detected is difficult to distinguish from other reflected waves, and other
reflections It was difficult to detect the longitudinal wave reflected wave LW5 clearly because it
overlapped with the wave.
[0029]
Therefore, in the ultrasonic sensor of this embodiment, the above problem is solved by setting
the height S of the acoustic lens 5 and the height H of the delay member 3 by any of the
following two methods. .
First, as shown in FIG. 11, in the first method, among the longitudinal wave reflected waves
(longitudinal wave repeated reflected waves) which are repeatedly reflected in the acoustic lens
5, the N + 1 longitudinal wave reflected wave, that is, in the illustrated example After or
simultaneously with the third longitudinal wave reflected wave LW 3, the transverse wave
reflected wave TW is returned, and the above N + 1 longitudinal wave repetitive reflection which
is the preceding or simultaneous longitudinal wave reflected wave of the transverse wave
reflected wave TW The time between the return of the wave LW3 and the return of the
longitudinal wave LW4 from the surface of the specimen 2 before that is the measurement area
SA for measuring the desired measurement depth range, and the measurement area The
longitudinal wave reflected wave LW5 from the boundary 2a located in the necessary
measurement depth range D in the specimen 2 in SA is to be returned.
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[0030]
As described above, in order to set the measurement area SA in relation to the required
measurement depth range D, the height S of the acoustic lens 5 and the height H of the delay
member 3 are obtained from the following equation . Here, the acoustic velocity of the
longitudinal ultrasonic wave in the acoustic lens 5 is VLC, the acoustic velocity of the longitudinal
ultrasonic wave in the delay member 3 is VLD, the acoustic velocity of the shear wave ultrasonic
wave in the delay member 3 is VSD, and the longitudinal direction in the specimen 2 The sound
velocity of the wave ultrasonic wave is VLM, and as shown in FIG. 11, the time difference A
between the longitudinal wave reflected wave LW4 from the surface of the specimen 2 and the
longitudinal wave repetitively reflected wave is repeated so that they do not overlap It is
determined in consideration of the attenuation time of the reflected wave.
[0032]
If N = 1, S will be too large, and if N = 4 or more, H will be too large, so N is preferably 2 or 3 and
N = 2 as in the example of FIG. It is most appropriate to do. FIG. 12 shows the relationship
between the required measurement depth range D and the height dimensions H and S obtained
by the above method.
[0033]
13 (a) and 13 (b) show the surface of the test specimen with the longitudinal wave repetitively
reflected waves RW1 (first), RW2 (second)... Detected by the conventional ultrasonic sensor and
the ultrasonic sensor of the above embodiment. 14 shows the longitudinal wave reflected wave
LW from and the transverse wave reflected wave TW from the surface of the specimen, and FIGS.
14 (a) and (b) show the FIGS. 13 (a) and (b) by enlarging the time axis. As shown in the figure, in
the conventional ultrasonic sensor, considerable noise is intruded into the measurement area SA,
but in the ultrasonic sensor of the above embodiment, almost no noise is present in the
measurement area SA.
[0034]
The second method is, as shown in FIG. 15, the (N + 1) th longitudinal wave reflection wave
among the longitudinal wave reflection waves (longitudinal wave repetition reflection wave)
repeating reflection in the acoustic lens 5, that is, the third in the illustrated example. So that the
transverse wave reflected wave TW is returned immediately before the longitudinal wave
reflected wave LW3, the transverse wave reflected wave TW from the surface of the specimen 2
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which is the preceding longitudinal wave reflected wave The time between the arrival of the
wave LW 4 and the arrival of the desired measurement depth range is taken as a measurement
area SA, and within the measurement area SA, the boundary 2a located within the required
measurement depth range D in the specimen 2 The longitudinal wave reflected wave LW5 from
the above is to be returned.
[0035]
As described above, in order to set the measurement area SA in relation to the required
measurement depth range D, the height S of the acoustic lens 5 and the height H of the delay
material 3 are obtained from the following equation 3 .
Here, the velocity of sound VLC, VLD, VSD, VLM are the same as in the previous method.
[0037]
Also in this case, if N = 1, then S becomes too large, and if N = 4 or more, H becomes too large, so
N is preferably 2 or 3 and N is as shown in the example of FIG. It is most appropriate to set it as =
2.
[0038]
Even when the height S of the acoustic lens 5 and the height H of the delay member 3 are
determined by the second method, the measurement area SA is measured by the ultrasonic
sensor of the above embodiment as in the first method. Noise can be eliminated.
[0039]
FIGS. 16 (a) and 16 (b) are explanatory views schematically showing an application example of
the contact type ultrasonic sensor with delay material of the above embodiment, where the
ultrasonic sensor of the above embodiment is an ultrasonic vibration. A motor-driven holder
comprising a holder 6 for holding the element 1, the acoustic lens 5 and the delay member 3 and
rotating the holder 6 about a predetermined axis TA substantially coinciding with the central axis
of the delay member 3 A pivot mechanism 7 is provided.
[0040]
In the contact type ultrasonic sensor with delay material of the above embodiment, since the
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acoustic lens 5 is formed by the ultrasonic transducer 1 and the delay material 3, the
arrangement error between the ultrasonic transducer 1 and the delay material 3 As a result, their
central axes do not coincide with each other and have a slight angle, and therefore, as shown in
FIG. 16A, the central axis of the delay member 3 and thus the rotational axis TA is slightly
inclined. A sound beam SB is emitted.
[0041]
Therefore, according to the ultrasonic sensor of the above application example, as shown in FIG.
16 (b), the ultrasonic sensor is disposed in a direction in which the rotation axis TA is
substantially orthogonal to the surface of the specimen 2 and the holder rotation mechanism By
rotating the holder 6 at 7, the ultrasonic beam SB can be scanned annularly around the point on
the specimen 2 intersecting the rotation axis TA, whereby the rotation axis TA is centered It is
possible to detect the change in depth of the boundary 2a within a certain range and hence the
minimum thickness of, for example, a remelt reinforcing layer within that range.
[0042]
As mentioned above, although it demonstrated based on the example of illustration, this
invention is not limited to the above-mentioned example, For example, the material etc. of a test
body or a delay material can also be changed as needed, Moreover, The purpose of use can be
used not only for detecting boundaries but also for flaw detection and the like.
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