JP3052050B2 - Meandering coil type electromagnetic ultrasonic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of scratches on the surface and inside of a conductive material, detection of residual stress, measurement of material properties (elastic coefficient, damping coefficient), damage and deterioration of the inside of a 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 view showing the structure of a conventional meandering coil type electromagnetic ultrasonic transducer of this type. As shown in the figure, a meandering coil type electromagnetic ultrasonic transducer has a meandering coil 1 on a flat steel plate 100 as an object to be measured.
01, and a permanent magnet 102 that forms a static magnetic field (bias magnetic field) is disposed on the upper part of the magnetic field.

When a high-frequency current is applied to the meandering coil 101 through the meandering coil type electromagnetic ultrasonic transducer having the above-described structure, a high-frequency current flows in a reverse direction immediately below the parallel portion of the meandering coil 101. As a result, Lorentz forces are generated in opposite directions, and ultrasonic waves 104 are generated in the steel sheet 100 in a direction perpendicular to the parallel lines. The ultrasonic waves 104 are reflected on the surface of the steel plate 100 or on the end face of a scratch, a defect, a crystal grain boundary, a structural change, or the like on the inside of the steel plate 100. When the reflected wave reaches near the surface,
A force is generated and an electric current is generated by the interaction between the force and the static magnetic field.
The surface and the inside are measured for flaws, defects, crystal grain boundaries, structural changes and the like.

[0004]

In the meandering coil type electromagnetic ultrasonic transducer of the above-mentioned conventional configuration, one coil is used for transmission for generating electromagnetic ultrasonic waves, and the other is used for reception having a sensing action. . For this reason, there is a problem that the S / N ratio is low and the gain cannot be increased.
In addition, there is no example in which the meandering coil 101 is disposed on the cylindrical object to be measured, and the surface or inside of the cylindrical object to be measured has scratches, defects,
Crystal grain boundaries, structural changes, etc. could not be measured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a meandering electromagnetic ultrasonic transducer which has a high S / N ratio and a large gain, improves performance, stabilizes quality, and achieves precision and miniaturization. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention relates to a meandering coil type electromagnetic ultrasonic transducer having a magnet for creating a static magnetic field and a meandering coil for creating an alternating magnetic field. Is an insulation sheet
Meandering coils made of a conductive material on both sides of the
The two snakes
One of the row coils is used for transmitting electromagnetic ultrasonic waves.
And the other is used for reception with a detection action,
And one end of the meandering coil is a through-hole.
Through the other surface to connect with the external lead wire,
The ends are connected so that the ground part is common, and both meandering
Coils are covered with insulating material and have high elasticity
It is characterized by having a meandering sheet coil .

[0007]

[0008]

[0009]

[0010]

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. FIG. 2 shows a schematic configuration of the transducer, and FIG. 3 shows the behavior of the surface of the measured object immediately below the coil. As shown in FIG. 2, the electromagnetic ultrasonic transducer includes a solenoid coil 2 for generating a static magnetic field and a meandering coil 3 for generating an alternating magnetic field, and a DC current 24 flows from a DC power supply 22 to the solenoid coil 2 for generating a static magnetic field. As a result, the object 5
Is magnetized by a static magnetic field 4, and then a high-frequency current 6 is passed from the controller 23 to the meandering coil 3 arranged perpendicularly to the magnetic field, as shown in FIG.
Immediately below the parallel portion 7, an alternating magnetic field 8 due to the high-frequency current 6 is generated perpendicular to the static magnetic field 4, and a composite magnetic field 10 is generated at an angle 9 with respect to the static magnetic field 4.

In the area 11 immediately below the adjacent coil, the combined magnetic field 1
The direction of 0 is symmetric with respect to the direction of the static magnetic field 4. Therefore, shear deformation occurs in the minute portion 12 of the DUT 5 due to the magnetostriction effect. When the direction of the alternating magnetic field 8 changes, 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 arrow 14 and is reflected on the end surface of the surface or the inside of the object 5 such as a flaw, defect, crystal grain boundary, or structural change, and proceeds to arrow 17 to reach the vicinity of the surface. The resulting 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.
Scratches, defects, crystal grain boundaries, structural changes, etc. on the surface and inside of the object 5 are measured.

FIG. 1 is a diagram showing a schematic configuration of a meandering sheet coil used in the meandering coil type electromagnetic ultrasonic transducer of the present invention, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is that of FIG. It is AA sectional drawing. As shown in the figure, the meandering sheet coil 30 is formed by winding three enameled wires by hand so as to be adjacent to each other and solidifying the enameled wire with a resin 31 to form a shape suitable for an object to be measured.

The middle one 3a of the meandering coil 3 is used for transmission for generating ultrasonic waves by electromagnetic action, and the two coils 3b on both sides are used for reception having a detection action. By providing transmission and reception separately in this way, the S / N ratio is increased and the gain can be increased.

FIGS. 4A and 4B show another schematic configuration example of the meandering sheet coil used in the meandering coil type electromagnetic ultrasonic transducer of the present invention. FIG. 4A is a plan view, and FIG. It is AA sectional drawing of a). Serpentine sheet coil 4
Reference numeral 0 denotes a meandering coil 42 and a meandering coil 43 made of a conductive material formed on both surfaces of an insulating sheet 41 made of a heat-resistant resin (for example, polyimide) by using an etching or printing technique, as is apparent from the figure. interposed an insulating sheet 41 disposed so as to face coincide with each other, the bonding the insulating sheet 44, 44 further with an adhesive surface on the and insulation of a heat-resistant surface and serpentine coil 43 of the serpentine coil 42 Structure.

Either the meandering coil 42 or the meandering coil 43 is used for transmitting ultrasonic waves by electromagnetic action, and the other is used for receiving which has a detecting action. Although it is not determined which one comes to the upper surface, since the electromagnetic ultrasonic transducer has better reception characteristics than the transmission, the transmission surface is usually located on the measured material side in many cases.

Next, a method of manufacturing the meandering sheet coil having the above configuration will be described with reference to FIG. First, as shown in FIG. 5A, 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 and cut to a predetermined external dimension. 45 is prepared by bonding with an adhesive.

Next, as shown in FIG.
5 is formed into a meandering shape by etching, and the meandering coil 4 is formed.
2, 43 (see FIG. 4) patterns are formed. The pattern may be formed by using a circuit printing technique.

Next, as shown in FIG. 5C, the insulating sheet 4 on which the patterns of the meandering coils 42 and 43 are formed.
A heat-resistant adhesive 46 is applied to the surface on the pattern formation side of No. 4. The adhesive 46 not only bonds an insulating sheet described later, but also plays a role as an insulating material between adjacent patterns (lines) of the meandering coils 42 and 43.

Next, as shown in FIG. 5D, a heat-resistant insulating sheet 41 is bonded to the upper surfaces of the meandering coils 42 and 43.

Next, as shown in FIG. 5 (5), an adhesive 47 is applied to the upper surface of the insulating sheet 41.

Next, as shown in FIG. 5 (6), an insulating sheet 44 on which the pattern of the meandering coils 42 or 43 formed in (2) of FIG. 5 is formed is formed in (5) of FIG. The meandering sheet coil 40 is completed by bonding to the adhesive 47 of the insulating sheet 41 thus completed. Note that one end (for example, 42a, 43a) of each of the meandering coils 42 and 43 is
9, through the insulating sheet 44 to the other surface, connected to the external lead wire, and the other end (for example, 42b, 43
b) is connected through a through hole 49 so that the ground portion is common (see FIG. 4).

The dimensions of the meandering sheet coil having the configuration shown in FIG. 4 based on the above manufacturing method are as follows. The outer dimensions of the insulating sheet 41 are length L = 44.5 m.
m, 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, thickness H1 = 0.025 mm, and meander frequency 48. . The meandering coils 42 and 43 had a resistance value of 12Ω and an inductance of 1 μH, and a meandering sheet coil 40 of a transducer having sufficient sensitivity in performance was obtained.

By adopting the configuration shown in FIG. 4 for the meandering sheet coil of the meandering coil electromagnetic ultrasonic transducer, the following excellent operational effects can be obtained.

First, the insulating sheet 41 is, for example, a polyimide-based heat-resistant insulating sheet having a size of about several tens of microns, and has a meandering coil 42 or 43 serving as a receiving coil with the insulating sheet 41 interposed therebetween. Meandering coil 43
Or 42 are arranged facing each other, so that the reflected wave of the transmitted wave can be caught at the same position. As in the conventional case, the middle one of the three lines is used as the transmission coil and the two on both sides are used as the transmission coil. More accurate measurement is possible than when a reception coil is used and reception signals are averaged.

Second, since the coil pitch interval W1 of the meandering coils 42 and 43 is significantly higher than that of the conventional manual winding, stable reception of ultrasonic waves becomes possible.

Third, by using the insulating adhesive 46 for bonding the insulating sheet 41, insulation between the meandering coils 42 and 43 is also possible.
It is possible to withstand the voltage before and after.

Fourth, by arranging coils on both sides compared to a conventional copper wire such as an enameled wire which is manually wound, uniform quality, miniaturization and precision, shortening of manufacturing time, and High functionality (improvement of S / N ratio) can be achieved by an ideal parallel coil.

Fifth, by making the meandering sheet coil 40 flat (sheet), it is rich in elasticity, and there is no unevenness between coils of the non-measurement object.

FIGS. 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 having the above structure. The meandering coil type electromagnetic ultrasonic transducer shown in FIG.
Numeral 0 is set on the outer periphery of the cylindrical object to be measured, and a magnetic circuit is formed between the hollow portion of the solenoid coil 2 for creating a static magnetic field and the hollow portion of the cylindrical object to be measured 5 through a core material 24 made of a magnetic material. As a result, a static magnetic field is generated in the axial direction of the device under test 5, and an ultrasonic wave (axially symmetric SH wave) is generated. In addition, the grounding 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, FIG.
The parts denoted by the same reference numerals indicate parts having the same action. The same applies to FIGS. 7 to 12.

The meandering coil type electromagnetic ultrasonic transducer shown in FIG. 7 has a solenoid coil 2 and an object 5 to be measured.
Are formed in a U-shape and both ends thereof are formed in a cylindrical shape (ring shape). The tubular portion 24a can be vertically divided at a central portion (solid line A portion). When the DUT 5 is mounted, the lower portion is removed, and the DUT 5 is inserted into the upper concave portion. Thereafter, the lower portion is connected to the upper portion by means not shown. By configuring the cylindrical portion 24a in this way, the diameter of both ends of the cylindrical DUT 5 is larger than the inner diameter of the hollow portion of the cylindrical portion 24a, and the DUT 5 cannot be passed through the hollow portion. However, the DUT 5 can be easily mounted on the cylindrical portion 24a.
The meandering 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 ultrasonic waves (axially symmetric SH waves).

In the meandering coil type electromagnetic ultrasonic transducer shown in FIG. 8, a cylindrical object 5 is passed through a hollow portion of a solenoid coil 2 for generating a static magnetic field.
A meandering sheet coil 40 is placed on the outer circumference of the object 5 to generate a static magnetic field in the longitudinal direction of the DUT 5 and generate ultrasonic waves (axially symmetric SH waves).

In the meandering electromagnetic ultrasonic transducer having the configuration shown in FIG. 9, a permanent magnet (or electromagnet) 25 for generating a static magnetic field of the plate-like object 5 is applied with a static magnetic field in the axial direction of the object. The two meandering sheet coils 40, 40 are arranged at a predetermined interval between them so as to generate them. One of the meandering sheet coils 40, 40 can be used for transmitting as usual, but both can be used for transmitting and receiving. In this case, since the ultrasonic waves are simultaneously generated from both, and are received at the same time, a higher S / N ratio can be obtained. In the figure, an ultrasonic wave (surface SH wave) signal is transmitted from the meandering sheet coil 40 for transmission on the left side to the meandering sheet coil 40 for reception on the right side.

The meandering type electromagnetic ultrasonic transducer having the structure shown in FIG. 10 is a meandering coil on the lower surface of one of the meandering sheet coils 40 (left side meandering sheet coil 40 in the figure) of the meandering type electromagnetic ultrasonic transducer shown in FIG. The controller 23 applies a voltage to the meandering coil on the lower surface of the other meandering sheet coil 40 (the right-hand meandering sheet coil 40 in the figure), and simultaneously transmits ultrasonic waves from the two meandering sheet coils 40 and 40, and the upper surface The signal is received by a meandering coil. With this configuration, the sensitivity is further improved. In FIG. 10,
The grounding portion E of the meandering coil (receiving coil) on the upper surface of the meandering sheet coil 40 and the grounding portion E of the meandering coil (transmitting coil) on the lower surface are connected to each other as in the case of FIG. Although not shown, the same applies to the cases of FIGS. The same applies to the case of FIG. 11 and FIG. 12 when both meandering coils on the upper and lower surfaces are used.

The meandering coil type electromagnetic ultrasonic transducer having the structure shown in FIGS. 11 and 12 is composed of a permanent magnet (or electromagnet) 25 for generating a static magnetic field in the thickness direction on a plate-like measuring object 5. DUT 5 and permanent magnet (or electromagnet) 2
5, two meandering sheet coils 40, 40 are arranged at predetermined intervals. Meandering sheet coils 40, 40
One of them is for transmission and the other is for reception. The wiring between the meandering sheet coils 40 and the controller, the main amplifier, and the preamplifier is substantially the same as that shown in FIGS. 9 and 10, so that the illustration thereof is omitted. 11 and 12, an ultrasonic wave (SO wave) signal is transmitted from the meandering sheet coil 40 for transmission on the right side to the meandering sheet coil 40 for reception on the left side. 10 and 11, (a) shows a front arrangement relationship between the permanent magnet (or electromagnet) 25 and the meandering sheet coil, and (b) shows a planar arrangement relationship.

In the configuration example of the meandering coil type electromagnetic ultrasonic transducer having the configuration shown in FIGS.
Is caused by the Lorentz force as the vibrating force for generating the ultrasonic wave, and the other is caused by the magnetostrictive force.

[0036]

According to <br/> invention described gun claim as described above, according to the present invention, excellent effects as described below can be obtained. (1) Arrange on both sides of the insulating sheet so that they face each other.
Transmits one of the placed meandering coils to generate electromagnetic ultrasonic waves
Since the other is used for reception having a detecting action ,
/ N ratio is high and gain can be increased.

[0037] (2) and serpentine sheet coil rich arrangement the resilient so that meander-shaped coil of electrically conductive material on both surfaces of the insulating sheet by interposing the insulating sheet is both serpentine coils facing coincide with each other , One end of the meandering coil
Through the other surface through the through hole
And connect the other end so that the grounding part is common.
The two meandering coils are each covered with insulating material.
Since the formation, improved performance, stability, uniform quality, reduction in size, reduction of production time, and (improvement of the S / N ratio) ideal higher performance by parallel coils becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a meandering sheet coil used for a meandering coil type electromagnetic ultrasonic transducer of the present invention;
FIG. 1A is a plan view, and FIG. 1B is an A-A view of FIG.
It is sectional drawing.

FIG. 2 is a diagram for explaining a measurement principle of a meandering coil type electromagnetic ultrasonic transducer.

FIG. 3 is a diagram for explaining the measurement principle of the meandering coil type electromagnetic ultrasonic transducer.

FIG. 4 is a diagram showing a schematic configuration of a meandering sheet coil used in the meandering coil type electromagnetic ultrasonic transducer of the present invention;
FIG. 1A is a plan view, and FIG. 1B is an A-A view of FIG.
It is sectional drawing.

FIG. 5 is a view for explaining a method of manufacturing a meandering sheet coil of the meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 6 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 7 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 8 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 9 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 10 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 11 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 12 is a diagram showing a schematic configuration example of a meandering coil type electromagnetic ultrasonic transducer of the present invention.

FIG. 13 is a diagram showing a schematic configuration of a conventional meandering coil type electromagnetic ultrasonic transducer.

[Explanation of symbols]

 2 solenoid coil 3 meandering coil 5 DUT 20 preamplifier 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-105960 (JP, A) JP-A-63-302360 (JP, A) Full-fledged Sho-63-111662 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01N 29/00-29/28 H04R 13/00

Claims (2)

(57) [Claims] 1. A meandering coil type electromagnetic ultrasonic transducer comprising a magnet for creating a static magnetic field and a meandering coil for creating an alternating magnetic field, wherein the meandering coil is made of a conductive material on both sides of an insulating sheet.
Meandering coils facing each other with the insulating sheet interposed therebetween.
And one of the two meandering coils is
For transmission to generate magneto-ultrasonic waves, the other has a sensing function
For independent reception, the meandering coil
Through one end of the
And the other end to the common ground.
So that the two meandering coils are connected
Elastic meandering sheet coil covered with edge material
Serpentine coil type electromagnetic acoustic transducer, characterized in that the. 2. A magnet for producing said static magnetic field, comprising a solenoid coil.
The meandering sheet coil and the entire circumference of the cylindrical DUT.
Arranged so as to cover the body, the hollow part of the solenoid coil
And that the hollow part of the DUT is connected with a magnetic core material
The meandering coil type electromagnetic ultrasonic transducer according to claim 1, wherein: