JP4734522B2 - Electromagnetic ultrasonic probe - Google Patents

Description

  The present invention relates to an electromagnetic ultrasonic probe used for non-destructive inspection or thickness measurement of an object to be measured, and more specifically, a unit magnet constituting a magnet body of the electromagnetic ultrasonic probe is excited. The present invention relates to an electromagnetic ultrasonic probe formed from a coil.

  The electromagnetic ultrasonic probe can generate ultrasonic waves in a conductor by electromagnetic interaction, and is composed of a plurality of unit magnets made of permanent magnets and current lines. A fluid temperature measurement method and a metal sample inspection method using a conventional electromagnetic ultrasonic probe are disclosed in Japanese Patent Laid-Open No. 2001-74557 (Patent Document 1) and Japanese Patent Laid-Open No. 2001-74759 by some of the present inventors. (Patent Document 2). In Patent Document 2, the deterioration of the metal material is detected by using a change in the propagation characteristics of ultrasonic waves. When a metal material such as stainless steel is used for a long time, the material deteriorates, and the propagation characteristics of ultrasonic waves change in the region where such material deterioration occurs. Therefore, the presence or absence of material deterioration can be determined by scanning the metal sample using the ultrasonic beam generated from the electromagnetic ultrasonic probe and detecting the reflected beam.

  FIG. 22 is an explanatory diagram of a conventional electromagnetic ultrasonic probe in Patent Documents 1 and 2. The magnet body 102 includes a plurality of unit permanent magnets 106 that are combined while reversing the magnetic poles. When a high frequency current is passed through the current line 104, an eddy current 110 flows in the sample 108 to be measured. The eddy current 110 interacts with the magnetic line of force m of the unit permanent magnet 106, and a Lorentz force f acts. This Lorentz force F generates longitudinal ultrasonic waves having the same frequency as the high-frequency current in the metal in the object to be measured.

  FIG. 23 is an explanatory diagram of a transverse wave ultrasonic oscillation mechanism using a conventional electromagnetic ultrasonic probe. In order to generate the transverse wave ultrasonic wave, the arrangement of the current line 104 with respect to the unit permanent magnet 106 in FIG. 23 may be changed, and the electromagnetic ultrasonic probe that generates the transverse wave ultrasonic wave also includes a plurality of unit permanent magnets 106. The magnet body 102 and the current line 104 are arranged in series, and the current line 104 is wound around the magnet body 102. The unit permanent magnets 106 are all designed to have the same magnet thickness d and are arranged so that adjacent unit permanent magnets 106 are in close contact with each other and the magnetic poles are alternately reversed.

  When a high frequency current is passed through the current line 104 in the direction of the arrow, an eddy current 110 (inductive current) in the direction of the arrow flows through the surface layer portion of the measurement object 108 due to electromagnetic interaction. The eddy current 110 interacts with the magnetic field m (dotted arrow) formed by the unit permanent magnet 106, and thereby the Lorentz force f in the measurement object 108 acts. Since the Lorentz force 110 is generated in a direction perpendicular to the traveling direction of the ultrasonic wave 112, the transverse ultrasonic wave 112 is generated in the measurement target object 108.

Regardless of whether the wave is a transverse wave or a longitudinal wave, when the wavelength of the ultrasonic wave is λ, the thickness of the unit permanent magnet 104 is d, and the incident angle of the ultrasonic wave is θ, the path difference of each ultrasonic wave is δ. Then, the ultrasonic waves strengthen each other in a direction satisfying the relational expression of δ = λ / 2 (here, δ = dsin θ). When the thickness of the object to be measured 108 is sufficiently larger than the magnet thickness d, the reinforcing ultrasonic waves form a directional ultrasonic beam.
JP 2001-74557 A JP 2001-74759 A

  The intensity of the ultrasonic wave generated by the conventional electromagnetic ultrasonic probe shown in FIGS. 21 and 22 is the intensity of the magnetic field generated from the unit permanent magnet constituting the electromagnetic ultrasonic probe and the amount of current flowing through the current line. Depends on. In addition, when a permanent magnet is used, a size larger than a predetermined size is required to obtain a sufficiently strong magnetic field as an electromagnetic ultrasonic probe, and it is difficult to reduce the size of a conventional electromagnetic ultrasonic probe. Met.

  Furthermore, since the permanent magnet constituting the conventional electromagnetic ultrasonic probe is formed of a hard material, a special processing technique is required to cut or bend the permanent magnet. It has been difficult to easily process an ultrasonic probe into a desired shape. Therefore, the manufacturing cost is greatly increased by manufacturing an electromagnetic ultrasonic probe having a desired shape in accordance with the shape of the object to be measured and the installation space.

  Accordingly, an object of the present invention is to provide an electromagnetic ultrasonic probe that can generate high-intensity ultrasonic waves, can freely adjust the pulse width and pulse interval of ultrasonic waves, and can be easily processed into a desired shape. It is.

  The present invention has been made to solve the above problems, and the first embodiment of the present invention is a magnet body in which a plurality of unit magnets are arranged, and a current between the magnet body and the object to be measured. In the electromagnetic ultrasonic probe, the unit magnet is a unit electromagnet which has an electric wire through which an ultrasonic wave is transmitted to the object to be measured by electromagnetic force or receives an ultrasonic wave propagated in the object to be measured. A plurality of unit electromagnets are arranged so that the direction of the generated magnetic field is alternately reversed, and an electromagnet body is configured. The electromagnetic ultrasonic probe can freely adjust the strength of the magnetic field generated from the electromagnet body. It is a tentacle.

  A second aspect of the present invention is an electromagnetic ultrasonic probe in which a plurality of unit electromagnets are arranged in series to form an electromagnet body, and the plurality of electromagnet bodies are arranged in parallel.

  A third aspect of the present invention is an electromagnetic ultrasonic probe in which the unit electromagnet is a plate electromagnet formed by winding an exciting coil in a plate shape.

  A fourth aspect of the present invention is an electromagnetic ultrasonic probe in which the unit electromagnet is a concave electromagnet formed by bending both ends of a plate electromagnet obtained by winding an exciting coil in a plate shape in the same direction. is there.

  According to a fifth aspect of the present invention, the unit electromagnet includes a region where the exciting coil is wound around the core body in the same direction, and a region where the winding direction of the exciting coil adjacent to the region is opposite. Electromagnetic ultrasonic probe.

  A sixth aspect of the present invention is an electromagnetic ultrasonic probe in which the core is formed of an insulator, a magnetic body, or a nonmagnetic body.

  A seventh aspect of the present invention is an electromagnetic ultrasonic probe in which heat dissipation means is installed on the electromagnet body.

  According to an eighth aspect of the present invention, voltage applying means including at least an LC circuit including a coil and a capacitor is connected to the electromagnet body, and a pulse magnetic field having a desired time width and intensity is generated by the voltage applying means. Electromagnetic ultrasonic probe.

  A ninth aspect of the present invention is an electromagnetic ultrasonic probe in which the LC circuit is connected in series in a plurality of stages.

  In a tenth aspect of the present invention, when the ultrasonic oscillation point and the focal point of the surface of the object to be measured corresponding to the midpoint in the magnet width direction of the unit electromagnet are connected by a line segment, the wavelength of the ultrasonic wave is λ Then, in the electromagnetic ultrasonic probe, the unit electromagnets are arranged so that the ultrasonic waves that converge at the focal point are strengthened when the lengths of adjacent line segments are shifted by λ / 2.

  An eleventh aspect of the present invention is a fan-shaped unit electromagnet in which the unit electromagnets are formed in a fan shape. The magnet bodies are formed by sequentially arranging the fan-shaped unit electromagnets having different magnet lengths from a small magnet length to a large magnet length. Is an electromagnetic ultrasonic probe configured to have a fan shape.

  A twelfth aspect of the present invention is an ultrasonic measurement apparatus including the electromagnetic ultrasonic probe according to any one of the first to eleventh aspects as an ultrasonic transmitter and / or an ultrasonic receiver.

  According to the first aspect of the present invention, the electromagnetic ultrasonic probe that transmits and receives the ultrasonic wave propagating in the measurement object is formed from the unit electromagnet, and the direction of the generated magnetic field is alternately reversed. Since an electromagnet body is configured by arranging a plurality of unit electromagnets, a magnetic field having a desired strength is generated, and high strength is obtained by electromagnetic interaction between the magnetic field and an eddy current induced in a measurement object by a current line. The ultrasonic wave can be generated. Furthermore, the winding method of the exciting coil constituting the unit electromagnet can be designed freely, and the unit magnet composed of the exciting coil is flexible. Therefore, the electromagnetic ultrasonic probe according to the present invention has an installation position and a covered portion. The desired shape can be designed according to the shape of the measurement object. In addition, when the electromagnetic ultrasonic probe according to the present invention is reduced in size and weight, an ultrasonic wave having an intensity equal to or higher than that of a conventional electromagnetic ultrasonic probe is increased by increasing the applied voltage. Sound waves can be generated.

  According to the second aspect of the present invention, since the unit electromagnets are arranged in series to form an electromagnet body, the ultrasonic waves can be propagated as an ultrasonic beam while strengthening in a predetermined direction. . Furthermore, since the electromagnet bodies are arranged in parallel, the ultrasonic waves can be generated in a region having a desired size and shape. The unit electromagnet according to the present invention is formed of an exciting coil, and it is easy to set the exciting coil to a desired size. Even if a plurality of the unit electromagnets are arranged in series, a small and lightweight ultrasonic probe is provided. A tentacle can be formed. In addition, when the widths of the unit electromagnets arranged in series are the same, the direction in which the ultrasonic waves are strengthened is uniquely determined from the wavelength of the ultrasonic waves and the width of the unit electromagnets. The propagation direction can be set easily.

  According to the third aspect of the present invention, since the unit electromagnet is a plate electromagnet formed by winding an exciting coil in a plate shape, the electromagnetic ultrasonic probe can be thinned. This thinned electromagnetic ultrasonic probe can be stacked in a plurality of layers, and the intensity of ultrasonic waves can be increased. Further, since the exciting coil is flexible, deformation processing such as bending the plate electromagnet according to the installation position and the shape of the object to be measured can be easily performed.

  According to the fourth aspect of the present invention, the unit electromagnet is a concave electromagnet formed by bending both ends of a plate electromagnet obtained by winding an exciting coil in a plate shape in the same direction. The surface facing the object to be measured is composed of only the facing surface through which a current flows in the opposite direction of the exciting coil, and a uniform magnetic field can be applied to a wide range of the object to be measured. When the plate electromagnet is wound so as to have a major axis direction and formed into a track shape, the opposing surfaces of the unit magnets are bent by bending both ends of the plate electromagnet in the same direction. Thus, a current in the opposite direction is linearly applied to both sides thereof, and a uniform magnetic field can be applied to the object to be measured.

  According to the fifth aspect of the present invention, the unit electromagnet includes a region where the exciting coil is wound around the core body in the same direction, and a region where the winding direction of the exciting coil adjacent to the region is opposite. Therefore, a uniform magnetic field can be applied to the measurement object. Furthermore, if the shape of the core body is selected according to the surface shape of the object to be measured, ultrasonic waves can be generated with high efficiency. When the surface of the object to be measured is a flat surface, a rectangular core body When the exciting coil is wound around, an ultrasonic wave can be generated in the object to be measured with high efficiency.

According to the sixth aspect of the present invention, when the core is formed of an insulator or a non-magnetic material, only the magnetic field from the excitation coil contributes to the generation of the ultrasonic wave, and the desired ultrasonic wave is highly accurate. Can be generated. As the insulator material or non-magnetic material, a plastic material such as acrylic or kapton, or a glass material such as SiO ₂ can be used. Moreover, an insulating coating such as enamel resin, polyimide resin or rubber material can be coated on a nonmagnetic material and used as the core. When the core body is formed of a magnetic body, the magnetic body is magnetized by the magnetic field of the exciting coil, and the magnetic field by the electromagnet body is enhanced, so that the ultrasonic oscillation efficiency is improved and high-intensity ultrasonic waves are used. Can be generated.

  According to the seventh aspect of the present invention, since the heat radiating means is installed in the electromagnet body, the heat generated by the resistance of the exciting coil is released to the outside. Changes in the electrical characteristics of the exciting coil can be prevented, and highly accurate flaw detection by the electromagnetic ultrasonic probe according to the present invention can be realized. As the heat radiating means, a metal material such as copper having high thermal conductivity or various materials can be used.

  According to the eighth aspect of the present invention, since voltage applying means including at least an LC circuit composed of a coil and a capacitor is connected to the electromagnet body, a pulse is generated from a current when discharging the electric charge stored in the capacitor. A voltage can be generated. Therefore, pulsed ultrasonic waves can be generated by the electromagnetic interaction between the pulse magnetic field generated by this pulse voltage and the eddy current induced by the current line. In addition, an ultrasonic wave can be generated by generating a pulse magnetic field having a desired time width and intensity by the voltage applying means.

  According to the ninth aspect of the present invention, since the LC circuit is connected in series in a plurality of stages, a plurality of currents having different phases are superimposed, and a pulse voltage close to a rectangle can be output stably. A rectangular pulse ultrasonic wave can be generated. Therefore, it is possible to provide an electromagnetic ultrasonic probe that enables highly accurate flaw detection in an object to be measured.

  According to the tenth aspect of the present invention, when the ultrasonic oscillation point and the focal point of the surface of the object to be measured corresponding to the midpoint in the magnet width direction of the unit electromagnet are connected by a line segment, the wavelength of the ultrasonic wave Is set to λ, the unit electromagnets are arranged so that the ultrasonic waves that converge at the focal point when the lengths of adjacent line segments are shifted by about λ / 2 are generated, so that high-intensity focused ultrasonic waves are generated. Can be made. Since the unit electromagnet can wind the exciting coil in a desired shape, an electromagnetic ultrasonic probe that generates a convergent ultrasonic wave can be easily manufactured.

  According to an eleventh aspect of the present invention, the unit electromagnet is a fan-shaped unit electromagnet formed in a fan shape, and the fan-shaped unit electromagnets having different magnet lengths are sequentially arranged from a small magnet length to a large one. Since the magnet body is configured to have a fan shape, the ultrasonic wave can be converged to a predetermined position in the measurement object, and flaw detection scanning or the like can be performed with high efficiency. In the unit electromagnet, the unit magnet body is designed so that a predetermined position on a line extending in the direction in which the ultrasonic waves are strengthened from the middle point thereof coincides with a direction in which the ultrasonic waves are strengthened from a position other than the middle point. ing. Furthermore, high-intensity convergent ultrasonic waves can be generated by designing the width of each unit magnet so that the focal points of the ultrasonic waves coincide with each other.

  According to the twelfth aspect of the present invention, by providing the electromagnetic ultrasonic probe according to the present invention as an ultrasonic transmitter and / or an ultrasonic receiver, an ultrasonic measuring apparatus with high output and high sensitivity is provided. Can be provided. When the electromagnetic ultrasonic probe according to the present invention is used as an ultrasonic transmitter, the voltage applied to the excitation coil can be freely adjusted, and an ultrasonic wave that generates a high-intensity ultrasonic wave on a measurement object. An acoustic measurement device can be provided. Furthermore, if the electromagnetic ultrasonic probe according to the present invention is used as an ultrasonic receiver, a large eddy current is generated even with respect to weak ultrasonic vibration, so that an ultrasonic measurement apparatus capable of observing a weak ultrasonic signal. Can be provided.

  Hereinafter, embodiments of an electromagnetic ultrasonic probe according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an electromagnetic ultrasonic probe according to the present invention. The electromagnetic ultrasonic probe is composed of an electromagnet body 2 and a current line 4 arranged on the lower surface of the electromagnet body 2. The electromagnet body 2 has a plurality of unit electromagnets 6 arranged in series. The unit electromagnet 2 is formed of an exciting coil, and the unit magnets 6 are arranged so that the current directions 6a and 6b of the exciting coil are alternately reversed. Therefore, when a voltage is applied to the unit electromagnet 6, a current flows through the exciting coil, and a magnetic field M is generated in which the magnetic poles are alternately reversed by electromagnetic induction. The number of unit electromagnets 6 can be freely adjusted. In FIG. 1, three unit electromagnets 6 are arranged.

  When a high-frequency current is passed through the current line 4 in the arrow direction 4a, an eddy current 10 (inductive current) flows in the arrow direction 10a in the surface layer portion of the measurement object 8 due to electromagnetic interaction. This eddy current 10 interacts with a magnetic field M formed by the unit electromagnet 6 to generate a Lorentz force F in the measurement object 8. This Lorentz force F generates an ultrasonic wave 12 having the same frequency as the high-frequency current in the measurement object 14.

In the unit electromagnet 6, the ultrasonic wave 12 generated at the midpoint in the magnet width direction and the ultrasonic wave 12 generated between the adjacent unit electromagnets 6 are opposite to each other because the direction of the magnetic field M is reversed. Lorentz force F acts and the phase of the ultrasonic wave is shifted by π. Accordingly, when the traveling distance of each ultrasonic wave 12 becomes a path, and the wavelength of the ultrasonic wave propagating through these paths is λ, the difference between these paths (path difference) δ is shifted by λ / 2, and each ultrasonic wave 12 Strengthen each other. That is, when the unit electromagnet bodies 6 have the same width W, the direction in which the ultrasonic waves strengthen each other is a direction that satisfies the condition (W / 2) · sin θ = λ / 2, and θ = sin ⁻¹ (λ / The incident angle θ satisfies the relational expression W). Here, the wavelength λ has a relationship of λ = V / f (V is the speed of sound) with respect to the frequency f of the high-frequency current passed through the current line. Are equal.

  FIG. 2 is a schematic configuration diagram of the plate-like unit electromagnet 6 according to the present invention. A rectangular unit electromagnet 6 is formed by winding the exciting coil 6 c in a plate shape, and the exciting coil 6 c is configured to have a thickness T of the unit electromagnet 6. However, the thickness T of the unit electromagnet 6 is not limited to the wire diameter. The connection line 7 of the excitation coil 6c is connected to an external power source or another adjacent excitation coil. As shown in the figure, when the exciting coil 6c is bent at a right angle, the current flowing through the exciting coil 6c is linearly energized so that the current directions 6a and 6b in the unit magnet 6 are completely reversed. Is formed.

  FIG. 3 is a schematic configuration diagram of the plate-like electromagnet body 2 according to the present invention. (3A) is a schematic plan view of the plate-like electromagnet body, in which five unit electromagnets 6 having the same width W and length L are arranged in series to form the electromagnet body 2. The electromagnet part of the electromagnetic ultrasonic probe is configured in parallel in two rows. By arranging such electromagnet bodies in parallel, a uniform ultrasonic plane wave is generated, and flaw detection can be performed with high accuracy.

  (3B) shows a schematic cross-sectional view of the plate-like electromagnet body 2. As described above, the unit electromagnets 6 are arranged in series so that the current directions 6a and 6b are alternately reversed, and a magnetic field M that is alternately reversed in the width direction is generated by energizing the current. The thickness T of the unit electromagnet 6 is determined from the wire diameter of the exciting coil 6c and the number of turns in the thickness direction. The ultrasonic probe according to the present invention can generate a magnetic field having sufficient strength even when the number of turns in the thickness direction of the exciting coil 6c is 1, and the smaller the number of turns in the thickness direction, the smaller the number of turns in the thickness direction. The amount of heat generated by the resistance of the exciting coil 6c can be preferably released to the outside. The plate-like electromagnet body 2 can be used as a heat radiating means by attaching an insulating material having high thermal conductivity.

  FIG. 4 is a schematic configuration diagram of the electromagnet body 2 covered with the coating film 14. Since the object to be measured 8 is a conductor, the electromagnet body 2 needs to be covered with an insulating film. (4A) is a plan view of the electromagnet body 2 coated with the coating film 14. By covering the electromagnet body 2 with the coating film 14 from both sides, it is possible to prevent the supplied current from leaking to the object 8 to be measured. Further, the connecting wire 7 exposed to the outside of the coating film 14 is also covered with an insulating film. (4B) shows a cross-sectional view of (4A), and the coating film 14 is covered from both surfaces of the electromagnet body 2. The thickness of the coating film 14 can be appropriately selected according to the space in which the electromagnetic ultrasonic probe is disposed and the maximum current amount. In the above-described embodiment, the insulation method using the coating film 14 is shown. However, the insulation coating of the electromagnet body 2 according to the present invention is not limited to the coating film 14, and the exciting coil itself is surely secured. If it is insulated, various coating materials can be used. For example, it can be coated with a paint having insulating properties.

  FIG. 5 is a schematic configuration diagram of an electromagnet portion having a two-layer structure according to the present invention. The plate-like electromagnet body 2 has a thickness T that is about the wire diameter of the exciting coil 6c, and a layer structure can be formed from the plurality of electromagnet bodies 2 in order to generate a magnetic field having a desired strength. In the electromagnet portion composed of the two-layer electromagnet body 2, each of these electromagnet bodies is covered with the coating film 14, thereby preventing current from leaking to the other electromagnet body 2. Further, the distance d between the electromagnet bodies 2 can be determined as appropriate, and is preferably separated to such an extent that the mutual heat is not conducted. The number of coating films between the electromagnet bodies 2 may be one.

  FIG. 6 is a schematic view of a track-type unit electromagnet 6 according to the present invention. If the unit magnet 6 has anti-symmetric current directions 6a and 6b, the exciting coil 6c can be wound in a curved shape as shown in the figure. In such a case, it is preferable that the track-shaped electromagnet is formed so that the straight portions in which the current directions 6a and 6b flow in opposite directions have a sufficient length. By bending in the same direction, the unit magnets 6 can be efficiently arranged to form the electromagnet body 2, which will be described in detail below.

  FIG. 7 is a schematic view of a concave unit electromagnet according to the present invention. (7A) shows a schematic view of the unit electromagnet 6 wound in the track shape, and this unit electromagnet 6 is composed of curved portions 16 and 16 and a straight portion 18. (7B) is a schematic view of a concave unit electromagnet, in which the bending portions 16, 16 are bent in the same direction. The unit magnets 6 can be arranged efficiently to form the electromagnet body 2, and further, the effect of the magnetic field generated by the bending portions 16, 16 of the exciting coil 6 c is suppressed, and a uniform magnetic field is obtained by the object to be measured. Can be applied.

  FIG. 8 is a schematic view of an electromagnet portion composed of the concave unit electromagnet 6 according to the present invention. The electromagnet portions 2 and 2 formed by arranging the concave unit electromagnets 6 in series are arranged in parallel to form the electromagnet portion. As shown in the figure, the bending portions 16 of the concave unit electromagnets 6 are bent so that the unit electromagnets 6 can be arranged efficiently, and uniform ultrasonic waves are generated by the magnetic field generated by the electromagnet portions. be able to. Each electromagnet body 2, 2 can be covered with the coating film 14, and may be housed in a packing member 20 made of an insulating material and / or a nonmagnetic material.

FIG. 9 is a schematic view of an electromagnet body 2 in which an exciting coil is wound around a core body. The unit electromagnet 6 includes a pair of winding regions 24 in which an exciting coil 6c is wound around the core body 22 in the opposite direction. Accordingly, a magnetic field M is generated between the center of the unit electromagnet 6 and the unit magnet 6 adjacent thereto. However, when the exciting coil 6c is wound around the core body 22, if the winding regions 24 are formed in a pair or more, the unit magnet body 6 does not need to be a minimum unit, and as shown in the figure, The electromagnet body 2 is composed of an odd number of winding regions 24. The core body 22 is formed of an insulator or a nonmagnetic material, and only the magnetic field from the exciting coil 6c contributes to the generation of ultrasonic waves. As the insulator material and / or non-magnetic material, a plastic material such as acrylic or kapton, or a glass material such as SiO ₂ is used.

  FIG. 10 is a schematic cross-sectional view of the electromagnet body 2 according to the present invention. (10A) is a schematic cross-sectional view of a core body 22 having an insulating coating 22b. The core 22 is formed by coating a nonmagnetic material 22a with an insulating coating 22b such as enamel resin, polyimide resin, or rubber material. . (10B) is a schematic cross-sectional view of the electromagnet body 2 including the heat dissipation means 22c. Since the unit electromagnet 6 generates heat by resistance, a heat radiating means 22c for releasing this heat to the outside can be provided. The heat dissipating means 22c is made of a metal material such as copper having high thermal conductivity or various materials having high thermal conductivity.

  FIG. 11 is a schematic view of the electromagnet bodies 2 arranged in parallel. Similarly to the electromagnet portion 1 shown in FIGS. 3 and 8, two electromagnet bodies 2 each having an exciting coil wound around the core body 22 are arranged in parallel so that the current directions 6a are opposite to each other. Part 1 is configured. As shown in the figure, when the core body 22 is rectangular, the electromagnet body 2 is efficiently disposed, and uniform ultrasonic waves can be generated within a predetermined range.

FIG. 12 is a schematic diagram of a pulse forming circuit according to the present invention. This pulse generation circuit includes a coil 26, a capacitor 28, and a load resistor 31, and this load resistor corresponds to an excitation coil that constitutes an electromagnetic ultrasonic probe. The electric charge stored in the capacitor is added as the current I ₁ and the current I ₂ at the junction 30 to become the combined current I. At this time, the current I ₁ and the current I ₂ have a phase difference due to a path difference.

FIG. 13 is a measurement diagram showing temporal changes in current in the pulse forming circuit shown in FIG. Here, dashed-dotted line in the figure, the time variation of the current I ₁ in FIG. 12, dotted line time variation of the current I _2, the solid line indicates the time variation of the combined current I. As described above, a pulse current is formed in these combined currents I due to a phase difference between the currents I ₁ and I ₂ . Such a pulse current forms a pulse shape closer to a rectangle as the number of LC circuits connected in series in a plurality of stages is increased. By connecting such a pulse forming circuit to the electromagnet body 2, a suitable pulse ultrasonic wave can be generated.

  FIG. 14 is a schematic diagram of pulse forming circuits connected in series in a plurality of stages. Each unit composed of an LCR circuit includes a coil 26 having an inductance L of 1 μH, a capacitor 28 having a capacitance of 0.63 μF, and a resistor 32 having a resistance value of 0.03Ω, and only the last unit has a coil 26 having an inductance L of 3 μH. , A capacitor 28 having a capacitance of 0.63 μF and a resistor 32 having a resistance value of 0.1Ω. Further, an excitation coil section 35 is disposed in the pulse forming circuit, and the measurement result of the discharge voltage of the excitation coil section by the voltmeter 37 is shown in FIG.

  FIG. 15 is a measurement layout view of pulsed ultrasonic waves using the electromagnetic ultrasonic probe according to the present invention. The ultrasonic transmitter 34 is composed of an electromagnetic ultrasonic probe according to the present invention, and a pulse forming circuit shown in FIG. 14 is connected to an excitation coil constituting the electromagnetic ultrasonic probe. Furthermore, three types of electromagnetic ultrasonic probes formed from plate-shaped, concave-shaped and wound-type electromagnet bodies are prepared, and ultrasonic measurement is performed using each electromagnetic ultrasonic probe. Yes. In addition, 11 units of the unit are connected to the pulse forming circuit. The maximum value of the applied voltage is set to 1500 V, the discharge cycle is set to 1 Hz, the characteristic impedance of the exciting coil is set to 1.3Ω, and the time width of the pulse voltage applied to the exciting coil is designed to be 16 μs. The ultrasonic transmitter 34 and the ultrasonic receiver 36 are placed on the object 8 to be measured, and a conventional electromagnetic ultrasonic probe using a permanent magnet is used as the ultrasonic receiver. In this measurement, the distance Dp between the ultrasonic transmitter 34 and the ultrasonic receiver is set to about 300 mm.

  FIG. 16 is a waveform diagram of the discharge voltage (Discharge Voltage) of the exciting coil section 35 in FIG. The waveform of the discharge voltage shown in the figure is the result of measurement by the voltmeter 37 shown in FIG. 14, the solid line is the excitation coil that forms the plate unit electromagnet, the alternate long and short dash line is the excitation coil that forms the concave unit electromagnet, and the broken line is The discharge voltage from the exciting coil which forms a winding type unit electromagnet is shown. From these results, it can be seen that a suitable pulse voltage was applied to each excitation coil by the pulse forming circuit.

  FIG. 17 is a comparison diagram of received ultrasonic signals using the electromagnetic ultrasonic probe according to the present invention and the conventional electromagnetic ultrasonic probe. The two pulse waveform signals shown in the figure are generated by an electromagnetic ultrasonic probe using a permanent magnet (PPM structure EMAT) and an electromagnetic ultrasonic probe using an electromagnet (pulse magnetic field EMAT). The signal waveform which the received ultrasonic wave was received by the same receiver is shown. From the ultrasonic reception signal generated by the PPM structure EMAT, the ultrasonic reception signal generated by the pulse magnetic field EMAT has a high intensity and a clear pulse signal is obtained. Furthermore, in the case of the electromagnetic ultrasonic probe according to the present invention, it is possible to further increase the voltage applied to the exciting coil, and to obtain a clear reception signal with a stronger intensity.

  FIG. 18 is a waveform diagram of an ultrasonic signal intensity (Signal Intensity) with respect to a magnetomotive force for the exciting coil. Here, the magnetomotive force is defined by the number of turns of the exciting coil × current density. As shown in FIG. 15, the signal intensity is a signal obtained by measuring the ultrasonic wave transmitted by the electromagnetic ultrasonic probe according to the present invention by the ultrasonic receiver 36. The ultrasonic signal intensity by the electromagnetic ultrasonic probe according to the present invention increases as the magnetomotive force increases, and when it approaches 4000 AT, it exceeds the ultrasonic signal intensity by the conventional PPM structure EMAT, and at 4000 AT or higher, the conventional signal intensity is increased. An ultrasonic signal intensity greater than that of EMAT is obtained.

FIG. 19 is a schematic view of an asymmetric ultrasonic probe according to the present invention. This asymmetric electromagnetic ultrasonic probe is characterized by an asymmetric arrangement in which the magnet widths W ₀ ... W _{n of the} unit electromagnets 6 change from large to small in the width direction. The electromagnet body 2 is composed of unit electromagnets 6 in which adjacent magnetic poles are alternately reversed. Since the unit electromagnet 6 formed from the exciting coil can be adjusted in size freely, the asymmetric ultrasonic probe can be easily manufactured.

  FIG. 20 is an explanatory diagram of an asymmetric electromagnetic ultrasonic probe according to the present invention. The traveling distance of the ultrasonic wave emitted from the ultrasonic oscillation point 40a corresponding to the unit electromagnet 6 having the maximum width on the measurement object surface 8a is defined as a path 42a. A surface perpendicular to the path 42a is a wave surface 44a. Assuming that the wavelength of the ultrasonic waves 12 propagating through these paths 42a is λ, the ultrasonic waves strengthen each other at the wavefront 44a when the difference (path difference) δ between these paths 42a is shifted by λ / 2. Similarly, when the path difference δ is shifted by λ / 2 with respect to the path 42b connecting the ultrasonic oscillation points 40b and 40b corresponding to the unit magnet body 6 having the minimum width and the wavefront 44b, the wavefront 44b is Sound waves strengthen each other. As shown in the figure, these ultrasonic waves converge at a focal point 45 to form a convergent ultrasonic wave.

FIG. 21 is a plan view of the electromagnet body 2 having a sector structure. Unit electromagnet 6 of the electromagnet body 2 has a planar shape is formed in fan shape, are sequentially arranged from one length L _n is large to small. In the unit electromagnet 6, the electromagnet body 2 is designed so that the tip positions in the direction in which ultrasonic waves reinforce (broken arrows) coincide. The unit electromagnet 6 according to the present invention is flexible because it is formed from the exciting coil 6c, and the unit electromagnet 6 having a fan-shaped structure can be easily formed. Further, by the length L _n of the unit magnet 6 is to reduce the magnet width W large, is larger magnet width W of the length L _n is a unit smaller magnet body, even the intensity at the focus of the ultrasound beam Can be enhanced.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications and design changes are included in the technical scope without departing from the technical idea of the present invention. Absent.

  The electromagnetic ultrasonic probe according to the present invention can freely adjust the intensity, pulse width, and / or pulse period of the ultrasonic wave, so that it can be used as an ultrasonic transmitter of an ultrasonic measurement device or a flaw detection device. The accuracy of the measurement method and the metal sample inspection method can be significantly improved. By generating high-intensity and high-frequency ultrasonic waves in an object to be measured such as a metal material, minute material deterioration can be detected. Furthermore, the electromagnetic ultrasonic probe can be used as a highly sensitive ultrasonic receiver by freely adjusting the applied voltage. Therefore, by using the electromagnetic ultrasonic probe according to the present invention, non-destructive and / or non-contact material deterioration in a metal material or in a metal pipe in a nuclear power plant or a chemical plant that handles harmful chemicals. Can be measured with high accuracy.

1 is a schematic configuration diagram of an electromagnetic ultrasonic probe according to the present invention. 1 is a schematic configuration diagram of a plate-shaped unit electromagnet according to the present invention. It is a schematic block diagram of the plate-shaped electromagnet body which concerns on this invention. It is a schematic block diagram of the electromagnet body by which the coating film 14 was coat | covered. It is a schematic block diagram of the electromagnet part of the 2 layer structure which concerns on this invention. 1 is a schematic view of a track-type unit electromagnet according to the present invention. It is the schematic of the concave unit electromagnet which concerns on this invention. It is the schematic of the electromagnet part comprised from the concave unit electromagnet which concerns on this invention. It is the schematic of the electromagnet body by which the exciting coil was wound around the core body. It is a section schematic diagram of an electromagnet object concerning the present invention. It is the schematic of the electromagnet body 2 arranged in parallel. 1 is a schematic diagram of a pulse forming circuit according to the present invention. It is a measurement figure which shows the time change of the electric current in the pulse formation circuit shown in FIG. It is the schematic of the pulse formation circuit connected in multiple stages in series. It is a measurement arrangement | positioning figure of the pulsed ultrasonic wave using the electromagnetic ultrasonic probe which concerns on this invention. It is a wave form diagram of the discharge voltage (Discharge Voltage) of the exciting coil part in FIG. It is a comparison figure of the received ultrasonic signal using the electromagnetic ultrasonic probe concerning the present invention, and the conventional electromagnetic ultrasonic probe. It is a wave form diagram of ultrasonic signal intensity (Signal Intensity) to magnetomotive force (Magneticmotive force) to an exciting coil. 1 is a schematic view of an asymmetric ultrasonic probe according to the present invention. It is explanatory drawing of the asymmetrical electromagnetic ultrasonic probe which concerns on this invention. It is a top view of the electromagnet body which has a fan-shaped structure. It is explanatory drawing of the conventional electromagnetic ultrasonic probe. It is explanatory drawing of the transverse wave ultrasonic oscillation mechanism by the conventional electromagnetic ultrasonic probe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electromagnet part 2 Electromagnet body 4 Current line 4a Arrow 6 Unit magnet body 6a Current direction 6b Current direction 6c Excitation coil 7 Connection line 8 Object to be measured 10 Eddy current 12 Ultrasonic wave 14 Coating film 16 Bending part 18 Linear part 20 Packing member 22 Core 22a Insulating coating 22b Non-magnetic material 22c Heat radiation means 24 Winding region 26 Coil 28 Capacitor 30 Junction point 31 Load resistance 32 Resistance 33 Pulse forming circuit 34 Ultrasonic transmitter 35 Exciting coil section 36 Ultrasonic receiver 37 Ammeter 40a Ultrasonic transmission point 40b Ultrasonic transmission point 42a Path 42b Path 44a Wavefront 44b Wavefront 45 Focus 102 Magnet body 104 Coil (current line)
106 Unit permanent magnet 108 Sample 110 Eddy current Dp interval d Distance F Lorentz force f Lorentz force L Length M Magnetic field m Magnetic field T Thickness W Width θ Incident angle δ Path difference

Claims (12)

A magnet body in which a plurality of unit magnets are arranged and an electric wire through which a current flows between the magnet body and the object to be measured, and ultrasonic waves are transmitted into the object to be measured by electromagnetic force or the object to be measured In an electromagnetic ultrasonic probe for receiving ultrasonic waves propagating in an object, the unit magnets are formed of unit electromagnets, and a plurality of the unit electromagnets are arranged so that the directions of generated magnetic fields are alternately reversed. The unit electromagnet includes a region where the exciting coil is wound around the core body in the same direction and an exciting coil adjacent to this region. An electromagnetic ultrasonic probe comprising a region in which the winding direction is opposite . An electromagnetic ultrasonic probe that has a magnet body in which a plurality of unit magnets are arranged and an electric wire through which a current flows between the magnet body and the object to be measured and transmits ultrasonic waves into the object to be measured by electromagnetic force. In the touch panel, the unit magnet is formed of a unit electromagnet including only an excitation coil, and a plurality of the unit electromagnets are arranged so that the direction of the generated magnetic field is alternately reversed. A pulse forming circuit is connected, and a pulse voltage is applied to the electromagnet body by the pulse forming circuit, and at the same time, a high-frequency current is passed through the wire that generates an induced current in the object to be measured. An electromagnetic ultrasonic probe characterized by transmitting pulsed ultrasonic waves to the head. An electromagnetic ultrasonic probe that has a magnet body in which a plurality of unit magnets are arrayed and an electric wire through which a current flows between the magnet body and the object to be measured and receives ultrasonic waves propagating in the object to be measured. In the child, the unit magnet is formed of a unit electromagnet including only an exciting coil, and a plurality of the unit electromagnets are arranged so that the direction of the generated magnetic field is alternately reversed, and a pulse is applied to the electromagnet body. When the forming circuit is connected, a pulse voltage is applied to the electromagnet body by the pulse forming circuit, and the ultrasonic wave propagates in the magnetic field formed in the object to be measured by the electromagnet body, the energization is performed to the electric wire. An electromagnetic ultrasonic probe characterized by detecting an induced current. The unit electromagnet, the electromagnetic ultrasonic probe according to claim 2 or 3 wherein is an excitation coil plate-shaped electromagnet formed by winding a plate shape. The unit electromagnet, the electromagnetic ultrasonic probe according to both ends of the plate-shaped electromagnets wound the exciting coil into a plate shape to claim 2 or 3 is concave electromagnets formed by bending in the same direction. The electromagnetic ultrasonic probe according to claim 4 or 5 , wherein the plate electromagnet is covered with an insulating film . The pulse forming circuit viewed contains an LC circuit composed of at least a coil and a capacitor, electromagnetic greater according to any of claims 2-6 for generating a pulsed magnetic field having a desired time width and strength by the pulse forming circuit Sonic probe. The electromagnetic ultrasonic probe according to claim 7 , wherein the LC circuit is connected in a plurality of stages in series. The electromagnetic ultrasonic probe according to claim 1, wherein a plurality of the unit electromagnets are arranged in series to form an electromagnet body, and the plurality of electromagnet bodies are arranged in parallel. When the ultrasonic oscillation point and the focal point of the surface of the object to be measured corresponding to the midpoint in the magnet width direction of the unit electromagnet are connected by a line segment, the wavelength of the ultrasonic wave is λ, and the length of the adjacent line segment The electromagnetic ultrasonic probe according to any one of claims 1 to 9, wherein the unit electromagnets are arranged so that ultrasonic waves converged on a focal point are shifted by λ / 2 in increments. The unit electromagnet is a fan-shaped unit electromagnet formed in a fan shape, and is configured such that the magnet bodies are fan-shaped by sequentially arranging the fan-shaped unit electromagnets having different magnet lengths from the smallest magnet length to the largest one. The electromagnetic ultrasonic probe in any one of Claims 1-10. An ultrasonic measurement apparatus comprising the electromagnetic ultrasonic probe according to claim 1 as an ultrasonic transmitter and / or an ultrasonic receiver.

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