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JPH09166584

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH09166584
[0001]
The present invention relates to detection of flaws on the surface and inside of a conductive
material, detection of residual stress, measurement of material properties (elastic coefficient,
damping coefficient), damage inside the material due to load, heat, etc. The present invention
relates to an electromagnetic ultrasonic transducer for detecting
[0002]
2. Description of the Related Art FIG. 13 is a diagram showing the configuration of a conventional
serpentine coil type electromagnetic ultrasonic transducer of this type. As illustrated, the
meandering coil type electromagnetic ultrasonic transducer arranges the meandering coil 101 on
the flat plate-like steel plate 100 which is the object to be measured, and arranges the permanent
magnet 102 forming the static magnetic field (biasing magnetic field) on the top Configuration.
[0003]
When high frequency current is supplied to the meandering coil 101 in the meandering coil type
electromagnetic ultrasonic transducer having the above configuration, high frequency currents in
opposite directions alternately flow immediately below the parallel portion of the meandering
coil 101. As a result, Lorentz forces are generated in opposite directions to each other, and
ultrasonic waves 104 are generated in the steel plate 100 in the direction perpendicular to the
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parallel line. The ultrasonic wave 104 is reflected at the surface or inside of the steel plate 100 at
an end face such as a flaw, a defect, a grain boundary, or a change in structure, and when this
reflected wave reaches the vicinity of the surface, a force is generated. A current is generated by
the action, and the current is used to measure scratches, defects, grain boundaries, and structural
changes of the surface and the inside of the steel plate 100 by the meandering coil 101.
[0004]
SUMMARY OF THE INVENTION The meandering coil type electromagnetic ultrasonic transducer
of the above-described conventional configuration is used for transmission that generates
electromagnetic ultrasonic waves, and the other has detection function and is used for reception
as well as one coil. . Therefore, there is a problem that the S / N ratio is low and the gain can not
be large. In addition, since there was no example in which the meandering coil 101 was disposed
on a cylindrical object to be measured, it was not possible to measure flaws, defects, grain
boundaries, and structural changes of the surface and the inside of the cylindrical object.
[0005]
The present invention has been made in view of the above-mentioned point, and it is an object of
the present invention to provide a meandering type electromagnetic ultrasonic transducer which
can achieve high performance with high S / N ratio and large gain, stable quality, precision and
miniaturization. To aim.
[0006]
SUMMARY OF THE INVENTION In order to solve the above problems, the invention according to
claim 1 is a meandering coil type electromagnetic ultrasonic transducer comprising a magnet for
generating a static magnetic field and a meandering coil for generating an alternating magnetic
field. Are provided separately for transmission for generating electromagnetic ultrasonic waves
and for reception having a detection function.
[0007]
The invention according to claim 2 is a meandering coil type electromagnetic ultrasonic
transducer comprising a magnet for generating a static magnetic field and a meandering coil for
generating an alternating magnetic field, wherein the meandering coil is formed of a conductive
material on both sides of an insulating sheet. It is characterized in that it is a serpentine sheet coil
disposed so as to face each other with the insulating sheet interposed therebetween.
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[0008]
In the invention according to claim 3, in the invention according to claim 2, one of the
meandering coils disposed on both sides of the insulating sheet is for transmitting
electromagnetic ultrasonic waves, and the other has a detection function. For signal reception,
independent of each other, one end of the serpentine coil is passed through the other side
through the through hole and connected to the external lead wire, and the other end is connected
so as to share the ground. It is characterized by having done.
[0009]
In the invention according to claim 4, in the invention according to claim 2 or 3, the magnet for
producing the static magnetic field is a solenoid coil, and the meandering sheet coil is provided
on the surface of a cylindrical object to be measured. And the hollow portion of the object to be
measured are connected by the core material of the magnetic body.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
2 and 3 are diagrams for explaining the measurement principle of the meandering coil type
electromagnetic ultrasonic transducer, and FIG. 2 shows the schematic configuration of the
transducer, and FIG. 3 shows the surface behavior of the object under measurement just below
the coil.
As shown in FIG. 2, the electromagnetic ultrasonic transducer comprises a solenoid coil 2 for
producing a static magnetic field and a meandering coil 3 for producing an alternating magnetic
field, and directs a DC current 24 from a DC power supply 22 to the solenoid coil 2 producing a
static magnetic field. Thus, the object to be measured 5 is magnetized by the static magnetic field
4 and then the high frequency current 6 is supplied from the controller 23 to the meandering
coil 3 disposed perpendicular to the magnetic field, as shown in FIG. Immediately under the
parallel portion 7, an alternating magnetic field 8 generated by the high frequency current 6 is
generated perpendicular to the static magnetic field 4, and a combined magnetic field 10 is
generated at an angle 9 direction with respect to the static magnetic field 4.
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[0011]
The direction of the resultant magnetic field 10 is symmetrical with respect to the direction of
the static magnetic field 4 immediately below the adjacent coil 11.
Therefore, shear deformation occurs in the minute portion 12 of the object 5 due to the
magnetism effect.
By changing the direction of the alternating magnetic field 8, an ultrasonic wave (axisymmetric
SH wave) 15 is generated in the direction of the arrow 14.
The ultrasonic wave 15 travels in the direction of the arrow 14 and is reflected by the end
surface of the surface or the inside of the object 5 such as a flaw, a defect, a grain boundary, or a
change in the structure. The interaction between the force 18 and the static magnetic field 4
produces a current 19. This current is detected by the meandering coil 3, amplified by the
preamplifier 20, further amplified by the main amplifier 21, and sent to the controller 23 for
analysis, so that flaws, defects and grain boundaries on the surface and the inside of the object to
be measured 5. Measure tissue changes etc.
[0012]
FIG. 1 is a view showing a schematic configuration of a meandering sheet coil used for the
meandering coil type electromagnetic ultrasonic transducer of the present invention, wherein
FIG. 1 (a) is a plan view, and FIG. 1 (b) is an AA of FIG. FIG. As shown in the drawing, the
meandering sheet coil 30 is formed into a shape suitable for an object to be measured while
hand-rolling three enameled wires so as to be adjacent to each other and solidifying them with
the resin 31.
[0013]
One middle 3a of the meandering coil 3 is used for transmission which generates an ultrasonic
wave by electromagnetic action, and two 2b on both sides have detection action and are used for
reception. By separately providing for transmission and reception as described above, the S / N
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ratio can be increased, and the gain can be increased.
[0014]
FIG. 4 is a view showing another schematic configuration of a meandering sheet coil used for the
meandering coil type electromagnetic ultrasonic transducer of the present invention, wherein
FIG. 4 (a) is a plan view and FIG. 4 (b) is an A--. It is A sectional drawing. In this meandering sheet
coil 40, meandering coil 42 and meandering coil 43 made of conductive material formed on both
sides of insulating sheet 41 made of heat resistant resin (for example, polyimide type) using
etching or printing technology are insulating sheets It has a structure in which the insulating
sheets 44 and 44 are bonded to each other with a heat-resistant and insulating adhesive between
the surface of the meandering coil 42 and the surface of the meandering coil 43 with the
interposing members 41 interposed therebetween.
[0015]
One of the meandering coil 42 and the meandering coil 43 is for transmitting ultrasonic waves
by electromagnetic action, and the other is for receiving having a detecting action. Although it is
not determined which is on the top, since the electromagnetic ultrasonic transducer has better
reception characteristics than transmission, the transmission surface is usually located on the
side of the material to be measured.
[0016]
Next, a method of manufacturing the serpentine sheet coil configured as described above will be
described based on FIG. First, as shown in (1) of FIG. 5, a copper foil having a thickness of about
18 to 70 μm is formed on a heat-resistant insulating sheet (for example, a polyimide resin sheet)
44 having a thickness of about 25 μm. Prepare 45 bonded with an adhesive.
[0017]
Next, as shown in (2) of FIG. 5, the copper foil 45 is etched to form a serpentine shape, and a
pattern of serpentine coils 42 and 43 (see FIG. 4) is formed. Of course, the pattern may be
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formed using a circuit printing technique.
[0018]
Next, as shown in (3) of FIG. 5, a heat-resistant adhesive 46 is applied to the surface on the
pattern formation side of the insulating sheet 44 on which the patterns of the meandering coils
42 and 43 are formed. The adhesive 46 not only adheres to an insulating sheet described later,
but also serves as an insulating material between adjacent patterns (lines) of the meandering
coils 42 and 43.
[0019]
Next, as shown in (4) of FIG. 5, the heat-resistant insulating sheet 41 is adhered to the upper
surfaces of the meandering coils 42 and 43.
[0020]
Next, as shown in (5) of FIG. 5, the adhesive 47 is applied to the upper surface of the insulating
sheet 41.
[0021]
Next, as shown in FIG. 5 (6), the insulating sheet 44 formed in FIG. 5 (5) is the insulating sheet
44 on which the pattern of the meandering coil 42 or 43 formed in (2) is formed. The serpentine
sheet coil 40 is completed by adhering to the adhesive material 47 of FIG.
In addition, one end (for example, 42a, 43a) of the meandering coils 42 and 43 communicates
with the other surface through the insulating sheet 44 through the through hole 49 and is
connected to the external lead wire, and the other end (for example 42b, 43b) ) Are connected
through the through hole 49 so that the ground portion is common (see FIG. 4).
[0022]
The example of the dimension which manufactured the meandering sheet coil of the structure
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shown in FIG. 4 based on the said manufacturing method is as follows.
The external dimensions of the insulating sheet 41 are length L = 44.5 mm, width W = 25 mm,
thickness H = 0.025 mm, meandering coils 42 and 43 have width L1 = 0.11 mm, pitch interval
W1 = 0.9 mm, The thickness H1 is 0.025 mm, and the meandering frequency is 48. The
resistance value of the meandering coils 42, 43 was 12 Ω, and the inductance was 1 μH, and a
meandering sheet coil 40 of a transducer having sufficient sensitivity for performance was
obtained.
[0023]
By adopting the configuration as shown in FIG. 4 for the serpentine sheet coil of the serpentine
coil electromagnetic ultrasonic transducer, the following excellent operational effects can be
obtained.
[0024]
First, the insulating sheet 41 is a heat-resistant insulating sheet of, for example, a polyimide type
having a size of several tens of microns, and meandering coils 42 or 43 serving as receiving coils
sandwiching the insulating sheet 41 and meandering serving as receiving coils. Since the coils 43
or 42 are disposed opposite to each other, the reflected waves of the transmitted wave can be
caught at the same position, and one of the middle lines among the three lines is used as the
transmitting coil as in the prior art. Using a book as a receiving coil, it is possible to perform
measurement with higher accuracy than in the case of averaging received signals.
[0025]
Second, since the coil pitch distance W1 of the meandering coils 42 and 43 is created with great
accuracy as compared with the conventional hand-wound, it is possible to receive a stable
ultrasonic wave.
[0026]
Thirdly, by using the insulating adhesive 46 for bonding the insulating sheet 41, insulation
between the coils of the meandering coils 42 and 43 becomes possible, and it becomes possible
to withstand a voltage of around 1000 V at the time of measurement. .
[0027]
Fourth, by placing the coil on both sides compared to the conventional hand-rolled coated copper
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wire such as enameled wire, quality equalization, miniaturization, refinement, shortening of
production time, and ideal Higher functionality (improved S / N ratio) by parallel coils is possible.
[0028]
Fifth, by flattening (sheeting) the meander sheet coil 40, it is rich in elasticity and there is no
unevenness between the coils of the non-measurement object.
[0029]
6 to 12 are views showing the configuration of a meandering coil type electromagnetic ultrasonic
transducer of the present invention using the meandering sheet coil of the above configuration.
In the meandering coil type electromagnetic ultrasonic transducer shown in FIG. 6, the hollow
portion of the solenoid coil 2 and the hollow portion of the cylindrical test object 5 for
generating a static magnetic field by placing the meander sheet coil 40 around the cylindrical
test object. A magnetic circuit is formed through the core material 24 made of a magnetic
material.
As a result, a static magnetic field is generated in the axial direction of the object 5 to generate
an ultrasonic wave (axisymmetric SH wave).
Further, the ground portions E of the meandering coil (receiving coil) on the upper surface of the
meandering sheet coil 40 and the meandering coil (transmitting coil) on the lower surface are
connected to each other.
In FIG. 6, the parts assigned the same reference numerals as in FIG. 1 indicate parts that perform
the same function.
The same applies to FIGS. 7 to 12.
[0030]
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In the meandering coil type electromagnetic ultrasonic transducer having the configuration
shown in FIG. 7, the core member 24 for magnetically coupling the solenoid coil 2 and the object
to be measured 5 is formed in a U shape, and its both ends are cylindrical (ring shape) It is
formed in.
The cylindrical portion 24a can be divided up and down at the central portion (solid line A
portion). When mounting the device under test 5, remove the lower portion and insert the device
under test 5 into the recess in the upper portion. Then, the lower part is coupled to the upper
part by means not shown. When the diameter of both ends of the cylindrical object to be
measured 5 is larger than the inner diameter of the hollow portion of the cylindrical portion 24a
by configuring the cylindrical portion 24a in this manner, the object 5 can not be passed through
the hollow portion However, the object to be measured 5 can be easily attached to the cylindrical
portion 24a. A serpentine sheet coil 40 is placed on the outer periphery of the cylindrical object
5 to generate a static magnetic field in the longitudinal direction of the object 5 to generate an
ultrasonic wave (axisymmetric SH wave).
[0031]
In the meandering coil type electromagnetic ultrasonic transducer having the configuration
shown in FIG. 8, a cylindrical object to be measured 5 is passed through the hollow portion of the
solenoid coil 2 for producing a static magnetic field, and the meandering sheet coil 40 is placed
on the outer periphery of the object 5 to be measured. A static magnetic field is generated in the
longitudinal direction of the object 5 to generate an ultrasonic wave (axisymmetric SH wave).
[0032]
In the meandering type electromagnetic ultrasonic transducer having the configuration shown in
FIG. 9, a static magnetic field is generated in the axial direction of the object to be measured of
permanent magnets (or electromagnets) 25 for generating a static magnetic field of the plate-like
object 5 to be measured. The two serpentine sheet coils 40, 40 are disposed at a predetermined
distance therebetween.
The serpentine sheet coils 40, 40 are conventionally used one for transmission, but both may be
used for transmission and reception. In this case, ultrasonic waves are simultaneously generated
from both sides and simultaneously received by both sides, so that a higher S / N ratio can be
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obtained. In the figure, an ultrasonic (surface SH wave) signal is sent from the transmitting
meander sheet coil 40 on the left side to the receiving meander sheet coil 40 on the right side.
[0033]
The meandering type electromagnetic ultrasonic transducer having the configuration shown in
FIG. 10 has a meandering coil and the other of the lower surface of one meandering sheet coil 40
(in the figure, the meandering sheet coil 40 on the left side) of the meandering electromagnetic
ultrasonic transducer shown in FIG. Voltage is applied from the controller 23 to the meandering
coil on the lower surface of the meandering sheet coil 40 (in the figure, the meandering sheet
coil 40 on the right side) and ultrasonic waves are simultaneously transmitted from the both
meandering sheet coils 40 and 40. In such a configuration, the sensitivity is further improved.
10, the ground portion E of the meandering coil (receiving coil) on the upper surface of the
meandering sheet coil 40 and the meandering coil (transmitting coil) on the lower surface are
connected to each other as in the case of FIG. It is. Moreover, although illustration is abbreviate |
omitted, the same may be said of the case of FIG. 7, FIG. Also in the case of FIG. 11 and FIG. 12,
the same applies to the case of using the both meandering coils of the upper and lower surfaces.
[0034]
The meandering coil type electromagnetic ultrasonic transducer having the configuration shown
in FIGS. 11 and 12 comprises a permanent magnet (or electromagnet) 25 for generating a static
magnetic field in the thickness direction on a plate-like object 5 to be measured; Two serpentine
sheet coils 40 are disposed between the permanent magnet (or electromagnet) 25 at a
predetermined interval. One of the serpentine sheet coils 40, 40 is for transmission and the other
is for reception. The wiring between the serpentine sheet coils 40 and the controller, and the
main amplifier and preamplifier is substantially the same as that shown in FIGS. 9 and 10, so the
illustration thereof is omitted. In FIG. 11 and FIG. 12, an ultrasonic (SO wave) signal is sent from
the transmission meandering sheet coil 40 on the right side to the reception meander sheet coil
40 on the left side. In FIGS. 10 and 11, (a) shows the front arrangement relation of the
permanent magnet (or electromagnet) 25 and the meander sheet coil, and (b) shows the plane
arrangement relation.
[0035]
In the configuration example of the meandering coil type electromagnetic ultrasonic transducer
having the configuration shown in FIG. 6 to FIG. 12, FIG. 11 shows that the excitation force for
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generating ultrasonic waves is due to Lorentz force, and the others are due to magnetostriction.
[0036]
As described above, according to the present invention, the following excellent effects can be
obtained.
(1) Since the serpentine coil is provided separately for transmission for generating
electromagnetic ultrasonic waves and for reception having a detection function, the S / N ratio is
high and the gain can be taken large.
[0037]
(2) A serpentine coil made of a conductive material is disposed on both sides of the insulating
sheet so that the both serpentine coils are opposed to each other with the insulating sheet
interposed therebetween to make the serpentine sheet coil rich in elasticity. Because it is an
electromagnetic ultrasonic transducer that has a serpentine coil and a serpentine coil for
reception, it can not be manufactured by hand, and its performance can be improved, its stability,
uniformity of quality, miniaturization, refinement, shortening of manufacturing time, and ideal
Parallel coil enables high functionalization (improvement of S / N ratio).
[0038]
Brief description of the drawings
[0039]
1 is a diagram showing a schematic configuration of a serpentine sheet coil used for the
serpentine coil type electromagnetic ultrasonic transducer of the present invention, the same
figure (a) is a plan view, the same figure (b) is a cross section AA of the same figure (a) FIG.
[0040]
2 is a diagram for explaining the measurement principle of the serpentine coil type
electromagnetic ultrasonic transducer.
[0041]
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3 is a diagram for explaining the measurement principle of the serpentine coil type
electromagnetic ultrasonic transducer.
[0042]
4 is a diagram showing a schematic configuration of a serpentine sheet coil used for the
serpentine coil type electromagnetic ultrasonic transducer of the present invention, the same
figure (a) is a plan view, the same figure (b) is a cross section AA of the same figure (a) FIG.
[0043]
5 is a diagram for explaining a method of manufacturing a serpentine sheet coil of the serpentine
coil type electromagnetic ultrasonic transducer of the present invention.
[0044]
6 is a diagram showing an example of a schematic configuration of the serpentine coil type
electromagnetic ultrasonic transducer of the present invention.
[0045]
7 is a diagram showing a schematic configuration example of a serpentine coil type
electromagnetic ultrasonic transducer of the present invention.
[0046]
<Figure 8> It is the figure which shows the outline configuration example of the meander coil
type electromagnetic ultrasonic transducer of this invention.
[0047]
<Figure 9> It is the figure which shows the outline constitution example of the meander coil type
electromagnetic ultrasonic transducer of this invention.
[0048]
10 is a diagram showing an example of a schematic configuration of a serpentine coil type
electromagnetic ultrasonic transducer of the present invention.
[0049]
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<Figure 11> It is the figure which shows the outline constitution example of the meander coil
type electromagnetic ultrasonic transducer of this invention.
[0050]
12 is a diagram showing a schematic configuration example of the serpentine coil type
electromagnetic ultrasonic transducer of the present invention.
[0051]
13 is a diagram showing a schematic configuration of a conventional serpentine coil type
electromagnetic ultrasonic transducer.
[0052]
Explanation of sign
[0053]
Reference Signs List 2 solenoid coil 3 meandering coil 5 measured object 20 preamp 21 main
amplifier 22 DC power supply 23 controller 24 core material 30 meandering sheet coil 40
meandering sheet coil 41 insulating sheet 42 meandering coil 43 meandering coil 44 insulating
sheet 45 copper foil 46 Adhesive 47 Adhesive
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