JPH07218477A - Searching device - Google Patents

Abstract

PURPOSE:To provide a searching device capable of searching thickness, buried foreign matter or an internal flaw for to a substance attenuating ultrasonic waves or a substance absorbing an electromagnetic wave. CONSTITUTION:When pulse voltage is applied to an exciting coil 16 from a power supply 12, a super-magnetostriction material 15 expands and contracts. This expansion and contraction is transmitted to a vibration piece 20 by a connection rod 21 and the vibration piece 20 is supported at its peripheral part by a damper 26 to be vibrated only in a specific direction. This vibration is absorbed by a damper 24 to be immediately attenuated. Since a sound-insulating cylinder 25 is in close contact with an object 101 to be searched by a wt. 13, the vibration wave generated by the vibration of the vibration piece 20 is transmitted to the object 101 to be searched without being leaked to the outside. A detection sensor 29 detects a transmitted vibration wave and a reflected vibration wave to output a detection signal. An operational processing part 14 calculates the thickness of the object 101 to be searched, the distance up to burried foreign matter 102 and the distance up to an internal flaw 103 on the basis of the detection signal of the detection sensor 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exploration device, and more particularly to a porous material such as earth and sand, concrete, refractory material and soft ceramics, a non-homogeneous non-metallic material, a viscoelastic material such as rubber and soft plastic, And fats, fresh concrete,
The present invention relates to an exploration device for exploring the thickness of highly viscous materials such as asphalt and the foreign substances buried inside these materials.

[0002]

2. Description of the Related Art The thickness of metallic materials and hard ceramics, the presence or absence of internal defects, the depth of liquids such as water and oil, and the presence of foreign substances (eg, fish schools in the sea) that are suspended or buried therein are investigated. An exploration device is described, for example, in "Ultrasonic Measurement", Noboru Niwa, March 1982, Shokoido, pages 65-93.

In this type of exploration device, the velocity of an acoustic vibration wave propagating in an object is uniquely determined by the density and elastic modulus of the object, and the acoustic vibration wave has at least one of density and elastic modulus. The principle is that a part of the object is reflected by the boundary surface of two different objects.

More specifically, in this type of exploration device, a pulse-like acoustic vibration wave having an extremely short width is transmitted from the transmitter closely attached to the surface of the object (liquid surface) toward the inside of the object. At the same time, time measurement is started. The transmitted acoustic vibration wave propagates inside the object at a unique propagation velocity that is uniquely determined by the density and elastic modulus of the object, and is eventually reflected by the end surface (bottom surface) of the object. If a defect or foreign matter is present inside the object, the defect or foreign matter is also reflected. The exploration device stops the time measurement when the acoustic vibration wave reflected by the end face etc. is received by the receiver, and the elapsed time from transmitting the acoustic vibration wave to receiving the reflected acoustic vibration wave. To get Then, the exploration apparatus obtains the thickness (depth) of the object or the distance to the defect and the foreign matter based on the progress result and the propagation velocity of the acoustic vibration wave.

Usually, as the acoustic vibration waves used in this type of exploration device, ultrasonic waves in the audible range (20 kHz) or higher (usually 100 kHz or higher and several MHz) are used. This is because the acoustic vibration wave has a characteristic that the directivity becomes stronger as the frequency thereof becomes higher, and the oscillation of the pulsed vibration wave having a narrow time width becomes easier. That is, by using the acoustic vibration wave having a high frequency, it is possible to accurately perform a search in a specific direction, and to detect a minute defect or a foreign substance (improve the resolution).

Further, as a conventional exploration device, an underground structure,
Alternatively, there is a so-called underground search radar that searches for buried objects in the soil. An exploration device of this type is, for example, V
The fact that the electromagnetic wave pulse in the HF band is reflected at the boundary surface having different electrical properties (dielectric constant) is used.

[0007]

On the other hand, it is necessary to accurately grasp the positions of pipes buried in earth and sand, concrete, etc. when rebuilding a building, subway construction, road construction, etc. It is considered to be extremely important.

However, ultrasonic waves are greatly attenuated by porous bodies, inhomogeneous substances, highly viscous substances and the like. Specifically, the propagation distance of ultrasonic waves to these substances is extremely short, and almost no propagation is possible with ultrasonic waves of 100 kHz or higher. That is, in conventional exploration equipment using ultrasonic waves, soil or concrete, refractory materials, and porous or heterogeneous materials such as soft ceramics, rubbers, viscoelastic materials such as soft plastics, and oils and fats, ready-mixed concrete, etc. However, there is a problem that it is not possible to perform exploration with respect to non-metallic materials such as high viscosity and slurry-like fluid.

Further, since the conventional ground-penetrating radar detects the boundary reflection due to the difference in permittivity, it cannot be applied to a conductive substance such as a brick containing carbon. is there. Furthermore, this type of ground-penetrating radar has a problem that it is very expensive. Therefore, in reality, no exploration device has been obtained that can be used in building construction, subway construction, road construction, etc.

The present invention provides a relatively simple and inexpensive probing device capable of probing the thickness, internal defects, and embedded foreign matter of an object having a large attenuation effect on ultrasonic waves. The purpose is to provide.

Another object of the present invention is to provide an inexpensive probing device having a relatively simple structure, which is capable of probing the thickness, internal defects and embedded foreign matter of a conductive object. And

[0012]

According to the present invention, a vibrating element driven by a giant magnetostrictive vibrating device in which the rising and falling characteristics of an exciting coil are highly responsive, and the vibrating direction and / or the direction perpendicular to the vibrating direction. A passive damper or an active damper acting on, a circuit attached to an exciting coil for detecting the transmission signal of the vibrating element or a transmission sensor, and a received signal reflected from the bottom surface of the non-metallic material and / or its internal defect or an embedded foreign matter. Exciting coil auxiliary circuit or receiving sensor to detect, time difference detection circuit to detect the time difference by comparing the waveforms of the transmitted signal and the received signal, and the vibration wave propagation of the non-metallic material preset or measured with the time difference A non-metal material thickness, an internal defect, and a distance calculation circuit for calculating the thickness of the non-metal material, an internal defect, and a distance to a buried foreign matter. Locator fine buried foreign matter can be obtained.

Further, according to the present invention, the thickness of the medium containing substantially no transmission of ultrasonic waves and the conductive substance,
In the exploration method for exploring the embedded foreign matter in the medium, and the internal defect of the medium, a vibration wave is generated using the vibration of the giant magnetostrictive element, and the vibration wave is transmitted toward the inside of the medium, A probe method is provided which receives a reflected wave to probe the thickness of the medium, the foreign matter embedded in the medium, and the internal defect of the medium.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. The exploration apparatus according to the present embodiment generates a vibration wave and receives a reflected vibration wave of the giant magnetostrictive vibration device 11, a power source 12 that drives the giant magnetostrictive vibration device, and a giant magnetostrictive vibration device 1 as an object to be searched.
An arithmetic processing unit 1 which performs a predetermined arithmetic operation based on the output of the giant pyramid 13 for bringing the 1 into close contact and the giant magnetostrictive vibration device 11.
4 and.

The giant magnetostrictive vibration device 11 is a Te-Fe-
It has a round bar-shaped giant magnetostrictive material 15 made of an intermetallic compound such as Dy (terbium-iron-dysprodium), around which an exciting coil 16 connected to a power supply 12 is wound. .

The giant magnetostrictive material 15 is 1500 to 2000 ppm.
Magnetostrictive property, compressive strength of 700MPs, 14000-250
It has an energy density of 00 J / m _{3 and} an electromechanical coupling coefficient of 75%. Further, the giant magnetostrictive material 15 has a preload effect that the magnetostriction rate increases when a magnetic field is applied while preload is applied in advance. It should be noted that the giant magnetostrictive material 15 also exhibits an inverse magnetostrictive effect (villari effect) in which magnetic characteristics are changed by applying mechanical strain, similarly to a general ferromagnetic material. Further, from the eddy current characteristics, the upper limit frequency f _c during continuous driving is f _c = 2ρ
_e / μ _s D ² , (ρ _e : electrical resistivity, μ _s : magnetic permeability,
D: diameter), and is about 1.7 kHz (1 kHz in practical use) for a giant magnetostrictive material with D = 6 mm. In addition,
In the case of pulse driving, up to several kHz is possible.

The exciting coil 16 is accommodated in a thin cylindrical yoke 17 made of a ferromagnetic material. At the upper and lower ends of the outer periphery of the yoke 17, screws are respectively cut, and a ferromagnetic base body 18 and a front lid 19 are screwed together. Here, the yoke 17, the base body 18, and the front lid 19 are
A magnetic closed circuit for the magnetomotive force of the exciting coil 16 is configured.

Inside the front lid 19, a part of a connecting rod 21 connecting the giant magnetostrictive material 15 and the vibrating piece 20 and a compression spring arranged between the flange 22 of the connecting rod 21 and the front lid 19. And 23 are accommodated. The compression spring 23 is for applying a preload to the giant magnetostrictive material 15 via the coupling rod 21 to improve the magnetostriction rate of the giant magnetostrictive material 15, and the compressive force thereof is the yoke 17
It can be adjusted by the screwing amount of the front lid 19 and the front lid 19. Further, a damper 24 made of rubber or synthetic resin having an appropriate vibration damping characteristic is disposed between the front lid 19 and the vibrating piece 20.

The base 18 is fixed to the upper end of the sound absorbing and sound insulating cylinder 25, and the vibrating piece 20 is supported by a cylindrical surface friction damper 26 near the lower end of the sound absorbing and sound insulating cylinder 25. The illustrated sound-absorbing sound-insulating cylinder 25 has a three-layer structure in which a sound-absorbing material 27 such as glass wool sheet, rubber, or plastic is sandwiched between an outer cylinder made of a high-density sound-insulating material and an inner cylinder.

A wave receiving sensor 29 is fixed to a notch on the lower surface side of the vibrating piece 20 via a damper 28. As the wave reception sensor 29, for example, a piezoelectric acoustic pickup can be used. Further, a thin pad 30 made of porous paper, cloth, woven metal cloth or the like is bonded to the lower surface of the vibrating piece 20 and the lower end surface of the sound absorbing and sound insulating cylinder 25.

The power supply 12 basically has a time width of 0.1 ms.
The following single pulsed current is generated. Details of the power source 12 will be described later.

The weight cone 13 serves to bring the giant magnetostrictive vibration device 11 into close contact with the object 101 to be searched by its weight. This heavy cone 13 is not always necessary,
The giant magnetostrictive vibration device 11 may be fixed to the object 101 to be searched by using another tension fixture.

The arithmetic processing unit 14 includes a sequence control circuit 3
1, a transmission / reception signal switching circuit 32, a preamplifier 33, a time difference detection circuit 34, a vibration wave propagation velocity setting device 35, a distance calculation circuit 36, and an oscilloscope 37.

Hereinafter, using the exploration apparatus of this embodiment, objects to be explored (for example, porous heterogeneous materials such as concrete, bricks, refractory materials and soft ceramics, viscoelastic bodies such as rubber and soft plastics) Thickness 101, Object 10
1 foreign matter inside (for example, rebar in concrete) 10
2 and a method of searching for defects (voids) 103 inside the object to be searched will be described.

First, the giant magnetostrictive vibration device 11 is placed on the object 101 to be searched. Giant magnetostrictive vibration device 11
Is pressed against the surface of the object to be searched 101 by the weight of the heavy cone 13, and the thin pad 30 is brought into close contact with the object to be searched 101. As a result, there is no gap between the giant magnetostrictive vibration device 11 and the search target object 101, and the vibration wave generated inside the giant magnetostrictive vibration device 11 is detected.
Can be efficiently propagated toward. Note that, in order to bring the giant magnetostrictive vibration device 11 into close contact with the object 101 to be searched, a layer of oil, water, or the like may be interposed instead of the thin pad 30.

Next, a drive current from the power source 12 is applied to the giant magnetostrictive vibration device 11 that is brought into close contact with the surface of the object 101 to be searched. The power supply 12 has a time width of 0.1 ms as described above.
The following single pulse current is generated as a drive current and supplied to the exciting coil 16.

The exciting coil 16 generates a pulsed magnetic field in response to the pulsed current supplied from the power source 12.
The giant magnetostrictive material 15 normally expands at a magnetostriction rate of 0.1% or more when a magnetic field is applied, and returns to its original state when the magnetic field disappears. That is,
The giant magnetostrictive material 15 expands and contracts by the pulsed magnetic field. For the purpose of improving the linearity of the magnetostrictive characteristic of the giant magnetostrictive material 15,
It is preferable to add a bias current to the pulsed current generated by the power supply 12. The magnitude of this bias current is set to about ½ of the pulse current amplitude so that the operation width of the giant magnetostrictive material 15 changes by about ½. The same effect can be obtained by applying a magnetic field to the giant magnetostrictive material 15 using a permanent magnet instead of the bias current.

When the giant magnetostrictive material 15 expands and contracts, the giant magnetostrictive material 15
The connecting rod 21 connected to oscillates in the vertical direction in the figure. As a result, the vibrating piece 20 vibrates. Since the vibrating piece 20 is supported by the damper 26 on the periphery (the direction vertical to the vertical direction in the drawing), it vibrates only in the vertical direction in the drawing and suppresses the vibration in the vertical direction. Further, the vertical vibration is also absorbed by the damper 24, and is rapidly attenuated after the magnetic field disappears. In order to damp the continuous vibration of the vibrating piece 20 as quickly as possible, it is desirable that the vibrating piece 20 be as light as possible. In this way, a pulsed oscillating wave having a very short duration of 0.2 to 0.5 ms with a small delay with respect to the exciting pulse current can be obtained. The frequency of this vibration wave is about 2 to 5 kHz.

The vibration wave generated by the vibration of the vibrating piece 20 is transmitted toward the inside of the object 101 to be searched. The propagation speed depends on the object 101 to be searched. Exploration target 1
The vibration wave sent to 01 propagates inside the object 101 to be searched, and is reflected by the foreign matter 102 inside the object 101 to be searched, the defect 103 inside the object 101 to be searched, and the bottom surface 104 of the object 101 to be searched. It

The wave receiving sensor 29 is provided with the vibration wave (transmitted signal) generated by the vibration of the vibrating element 20 and the object 101 to be searched.
Foreign matter 102 inside, defect 10 inside the object 101 to be searched
3 and the reflected vibration wave (received signal) reflected by the bottom surface 104 of the object 101 to be searched, and outputs a detection signal to the transmission / received signal switching circuit 32.

The transmission / reception signal switching circuit 32 is controlled by the sequence control circuit 31 and switches between the transmission operation and the reception operation. In other words, the sequence control circuit 31 switches the transmission / reception signal switching circuit 32 to the transmission operation when the vibration wave is transmitted from the giant magnetostrictive vibration device 11 for a predetermined time (a short time of 0.1 ms or less). Therefore, after the elapse of time (when the transmitted oscillation wave can be detected), the operation is switched to the reception operation. As a result, the detection signal from the wave receiving sensor 29 is divided into a signal based on the wave transmission signal and a signal based on the wave reception signal.

The detection signal output from the transmission / reception signal switching circuit 32 is amplified by the preamplifier 33 and input to the time difference detection circuit 34 and the oscilloscope 37. here,
When there is a large difference in the signal level between the detection signal based on the transmission signal and the detection signal based on the reception signal, the preamplifier 33 amplifies the transmission signal and the reception signal with different amplification factors. A switching circuit or the like may be provided so as to perform this.

The time difference detection circuit 34 detects the time difference from when the vibration wave is transmitted to when the reflected vibration wave is received, based on the detection signal from the transmission / reception signal switching circuit 32.
The time difference signal is output to the distance calculation circuit 36. The distance calculation circuit 36 determines the thickness of the object to be searched 101 and the distance to the foreign matter 102 based on the propagation speed of the vibration wave preset in the vibration wave propagation speed setting unit 35 and the time difference signal from the time difference detection circuit 34. , And the distance to the defect 103 are calculated. Further, the oscilloscope 37 displays the detection signal from the transmission / reception signal switching circuit 32 on the CRT screen so that the time difference between transmission and reception can be visually perceived.

Thus, in the exploration apparatus of this embodiment,
The thickness of the object 101 to be searched, the distance from the surface to the foreign substance 102, and the distance from the surface to the defect 103 can be obtained. Further, using the exploration device of this embodiment,
In order to specify the positions of the foreign matter 102 and the defect 103 three-dimensionally, the measurement can be performed at at least three places and the results can be calculated. If it is known in advance that the pipe is buried along a certain direction like a buried pipe, the position of the pipe in one cross section may be obtained. Therefore, in such a case, the two-dimensional position of the pipe can be obtained by measuring at two points. When using a plurality of surveying devices at three or two locations, it is desirable to shift the transmission timings of the plurality of surveying devices in a time division manner in order to prevent interference or the like.

The exploration apparatus of this embodiment has a magnetostriction rate of 0.1% or more and a large energy density (25 × 10 ³ J / m ³ ; 20 times or more that of a piezoelectric element) as described above. By using a magnetostrictive material to generate a vibration wave of a large vibration energy at a low frequency as compared with the case of using a PZT (piezoelectric element), various types of non-exposure which cannot be performed by an ultrasonic probe are used. It is possible to search for metallic materials.

Next, the power supply 12 will be described in detail. In the above embodiment, the power supply 12 was described as merely generating a pulsed current, but the current flowing through the exciting coil 16 is delayed in rising and falling due to the influence of self-inductance and the like. This delay blunts the waveform of the vibration wave generated by the giant magnetostrictive vibration device 11 and reduces the resolution in the search. Therefore, the excitation coil 1
The drive current must be generated by the power supply 12 so that the current flowing in 6 becomes a rectangular wave.

As shown in FIG. 2, the power source 12 usually has a constant voltage source 41 connected in series to the exciting coil 16, a transistor 42, and a freewheel diode 43 connected in parallel to the exciting coil 16. ing. This power supply 1
In FIG. 2, when the transistor 42 is turned on and off, the rectangular wave pulse voltage from the constant voltage source 41 is applied to the exciting coil 16. At this time, the current flowing through the exciting coil 16 is delayed in rising and falling, and does not become a rectangular wave current as shown in FIG.

To make the rising of the current flowing through the exciting coil 16 steep, a so-called two-stage power supply method may be used.
That is, as shown in FIG.
Voltage VH higher than the steady voltage is applied to the excitation coil 1
6 After the flowing current reaches a predetermined value, the steady voltage VL may be applied. At this time, the current flowing through the exciting coil 16 has a sharp rise as shown in FIG.

Further, in order to improve the fall of the current flowing through the exciting coil 16, the freewheel diode 43 is removed from the circuit of FIG. 2 so that the energy stored in the exciting coil 16 is consumed by the transistor 42. You can do this. In this case, an induced voltage control method using a freewheel diode and a constant voltage diode is adopted so that the counter electromotive force generated in the exciting coil 16 does not exceed the collector-emitter withstand voltage V _CEO of the transistor 42. Just do it.

FIG. 5 shows a circuit of the power supply 12 which employs the two-stage power supply method and the induced voltage control method. In FIG. 5, when the transistors 51 and 52 are turned on,
The voltage VH from the high voltage power supply 53 is applied to the exciting coil 16 via the transistor 54 and the resistor 55. Next, when the transistor 51 is turned off while the transistor 52 is turned on, the transistor 54 is turned off.
The voltage VL of the steady voltage source 57 is applied to the exciting coil 16 via the diode 56 and the resistor 55. After that, when the transistor 52 is turned off, the energy stored in the exciting coil 16 is consumed by the transistor 52. At this time, since the counter electromotive voltage generated in the collector of the transistor 52 is clamped by the freewheel diode 58 and the constant voltage diode 59, it does not exceed the collector-emitter withstand voltage V _CEO of the transistor 52.

The power supply circuit shown in FIG. 2 can obtain a coil drive current having a time width of at most 0.5 ms, but the power supply circuit shown in FIG. 5 can obtain a rectangular drive pulse current of 0.1 ms or less. . Therefore, the resolution of the exploration apparatus using the power supply circuit of FIG. 5 is much higher than that when the power supply circuit of FIG. 2 is used.

In the above embodiment, the vibrating piece 20 is used to transmit the vibration wave. However, as described above, it is desirable that the vibrating piece 20 be light in weight.
When the surface of 1 is firm, the vibrating piece 20 may be omitted and the coupling rod 21 may directly strike the object to be probed to transmit the vibration wave. However, in this case, the wave receiving sensor 29 is housed in a separate container together with the damper 28, is arranged adjacent to the giant magnetostrictive device 11, and the damper 24
Must act between the front lid 19 and the object 101 to be probed, and the damper 26 must act on the side surface of the connecting rod 21.

Next, a second embodiment will be described with reference to FIG. Here, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the exploration apparatus of this embodiment, the giant magnetostrictive material 15 is directly connected to the vibrating piece 20 without the coupling rod 21. Further, the compression springs 23 that apply pressure to the giant magnetostrictive material 15 are evenly arranged around the yoke 17 (for example, three pieces form an angle of 120 °), and are connected to the base body 18 and the vibrating piece 20. ing. Further, the exploration apparatus of this embodiment has a current detector (not shown) that detects a current accompanying the wave transmission and wave reception flowing in the exciting coil 16, instead of the wave reception sensor 29. The current detector may detect a current flowing through a detection coil provided in addition to the exciting coil 16. Further, there is a delay time difference between the time from the current flowing in the exciting coil 16 to the transmission of the vibration wave and the time from the reception of the reflected vibration wave to the current flow in the coil. Therefore, a time difference adjusting circuit (not shown) is provided in the transmitting / receiving signal switching circuit 32.
Built into. In addition, in the exploration device according to the present embodiment, the tip of the sound absorbing and sound insulating cylinder 25 is tapered so that it cannot be easily inserted into earth or sand.

In the exploration apparatus of this embodiment, one end is fixed to the lower end of the inner cylinder of the sound absorbing and sound insulating cylinder 25 and the other end is the vibrating piece 2.
A plurality of support pieces 61 fixed to 0 and supporting the vibrating piece 20.
have. The support pieces 61 are evenly arranged around the vibrating piece 20 as shown in FIG. Also, the support piece 6
A strain sensor 62 for detecting the strain of the support piece 61 is provided on each of the upper surface and the lower surface of 1.

Furthermore, the exploration device of this embodiment is provided with the vibrating element 2
It has a brake ring 63 for stopping the vibration of 0 and a cover 64 for preventing invasion of earth and sand. The brake ring 63 has two ring members as shown in FIG. 7 (b). The end of each ring member is pressed against a piezoelectric element 72 attached to a holding seat 71 fixed to the sound absorbing and sound insulating cylinder 25. Piezoelectric element 72
Is controlled by a vibration suppression control circuit (not shown) connected to the power supply 12 and the strain sensor 62.

Next, the operation of the exploration apparatus of this embodiment will be described. The exploration apparatus of this embodiment is effective for exploring the thickness of earth and sand and the embedded foreign matter therein. Also in the exploration apparatus of this embodiment, similarly to the first embodiment, the vibrating reed 20 vibrates in accordance with the drive current supplied from the power source 12, and the vibration wave is transmitted toward the inside of the exploration target. . Here, assuming that the drive current supplied from the power source 12 to the exciting coil 16 is the drive current i _d as shown in FIG. 8A and the brake ring 63 is not present, the vibration displacement S _{v of the} vibrating piece 20 is assumed. Becomes as shown by the broken line in FIG.
That is, the vibrating piece 20 performs continuous vibration. Since such continuous vibration makes it difficult to receive the reflected vibration wave, it must be rapidly attenuated. Therefore, in the exploration device of this embodiment, the vibration of the vibrating piece 20 is converted into the strain of the support piece 61, and the strain is detected by the strain sensor 62. The output of the strain sensor 62 is input to the vibration suppression control circuit. When the drive current output from the power supply 12 rises once and then falls below a predetermined value i _o , the vibration suppression control circuit applies a voltage to the piezoelectric element 72 for a predetermined time (for example, a short time of 0.1 ms or less). To supply. The magnitude of this voltage is proportional to the detection signal from the strain sensor 62. Note that the vibration suppression control circuit may control the piezoelectric element 72 only in response to a change in the drive current without using the strain sensor.

The piezoelectric element 72 is extended by energization from the vibration suppression control circuit and presses the brake ring 63 against the vibrating piece 20. As a result, the vibration of the vibrating piece 20 is attenuated, and its vibration displacement S _v is (0.
Pulse-like mechanical vibration with a time width of 2 ms or less).

The vibration wave generated by the vibration of the vibrating piece 20 is reflected by the bottom surface of the object to be searched, foreign matter in the object to be searched, internal defects of the object to be searched, and vibrates the vibrating piece 20. Due to this vibration, a current flows through the exciting coil 16 due to an inverse magnetostriction (villari) effect.

The current detector detects the current flowing through the exciting coil 16 and outputs it to the transmission / reception signal switching circuit 32. The transmission / reception signal switching circuit 32 adjusts the delay time difference of the input detection signal. After that, similarly to the first embodiment,
The thickness of the object to be searched, the distance to the foreign matter in the object to be searched, and the distance to the internal defect of the object to be searched are obtained.

Next, a third embodiment of the present invention will be described with reference to FIG. Also in this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the exploration device according to this embodiment, the vibrating piece 20 has two upper and lower
It is divided into sheets, and a plastic film 91 such as a polyimide film is sandwiched between them. The outer peripheral portion of the plastic film 91 is fixed to the inner cylinder of the sound-absorbing sound-insulating cylinder 25 by using a pressing fitting 92. In addition, the connecting rod 21
Has a flat tip and is in contact with the vibrating piece 20 without being fixed. Further, between the front lid 19 and the vibrating piece 20, a first piezoelectric element 93 for detecting the vibration of the vibrating piece and a second piezoelectric element 94 for damping the vibration of the vibrating piece 20 are provided. . The first piezoelectric element 93 and the second piezoelectric element 94 are
As shown in FIG. 10, they are alternately arranged at a predetermined angle.

The exploration apparatus of this embodiment is used for exploring the depth of a highly viscous fluid in which ultrasonic waves are greatly attenuated and buried foreign matter therein. In particular, it is effective for an electroconductive highly viscous fluid that absorbs electromagnetic waves and a highly viscous fluid that contains electroconductive fine powder.

When a pulsed driving current (time width 0.1 ms or less) is applied to the exciting coil 16 from the power source 12, the connecting rod 21 collides with the vibrating piece 20 and the vibrating piece 20 vibrates.
The vibration of the vibrating piece 20 is detected by the first piezoelectric element 93. The detection output of the first piezoelectric element 93 is output to the arithmetic processing unit 14 and the servo amplifier (not shown). The servo amplifier amplifies the detection output of the first piezoelectric element 93 with a predetermined amplification factor and outputs it to the second piezoelectric element 94. The second piezoelectric element 94 operates as an active damper that attenuates the vibration of the vibrating piece 20 by the output of the servo amplifier. If the output of the servo amplifier is finished in a short time of 0.1 ms or less, the vibration wave can be made into a pulsed vibration wave having a time width of 0.2 ms or less, as in the second embodiment. . After that, the first piezoelectric element 93 operates as a wave receiving sensor, and based on the output of the first piezoelectric element 93, the thickness of the object to be searched and the like are searched, as in the first and second embodiments. .

In each of the above-mentioned first to third embodiments, the case where the pulse current is applied to the exciting coil 16 to transmit the pulsed vibration wave has been described.
The width of the pulse current is increased to about 4 to 5 ms to perform stepwise driving, and the received signal of the reflected wave is detected while the coil current (displacement of the vibrating element 20) maintains a substantially constant value after rising. You may Specifically, at the time of transmission, the transmission timing can be detected by differentiating the stepped waveform, and the reception signal can be detected by separating the received signal that arrives thereafter with a filter or the like. In the structure driven by the step-like waveform as described above, a damper for attenuating the transmitted wave becomes unnecessary.

[0054]

According to the present invention, a vibrating element is vibrated by using a giant magnetostrictive material, so that a low-frequency, high-energy vibrating wave can be obtained, and a porous material that cannot be probed by ultrasonic waves. It is possible to search for objects, inhomogeneous materials, highly viscous materials, and conductive materials that cannot be searched by radar.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a general power supply.

FIG. 3 is a graph showing a current flowing through the exciting coil of FIG.

FIG. 4 is a diagram for explaining a two-stage power supply method,
(A) is a graph which shows the voltage applied to an exciting coil, (b) is a graph which shows the current which flows into an exciting coil.

FIG. 5 is a circuit diagram of a power supply adopting a two-stage power supply method and an induced voltage control method.

FIG. 6 is a cross-sectional view of a giant magnetostrictive vibration device used in the exploration apparatus according to the second embodiment of the present invention.

7A is a sectional view taken along the line AA of FIG. 6, and FIG.
FIG. 6 is a sectional view taken along line BB of

8A and 8B are diagrams for explaining the operation of the giant magnetostrictive vibration device of FIG. 6, wherein FIG. 8A is a graph showing a current input to an exciting coil, and FIG. 8B is a graph showing a displacement of a resonator element. is there.

FIG. 9 is a partial sectional view of a giant magnetostrictive vibration device used in a third embodiment of the present invention.

10 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

 11 Giant Magnetostrictive Vibration Device 12 Power Supply 13 Frustum 14 Processing Unit 15 Giant Magnetostrictive Material 16 Excitation Coil 17 Yoke 18 Base 19 Front Lid 20 Vibrating Element 21 Coupling Rod 22 Tsuba 23 Compression Spring 24 Damper 25 Sound Absorbing Sound Insulation Tube 26 Cylindrical Surface Friction Damper 27 Sound absorbing material 28 Damper 29 Wave sensor 30 Thin wall pad 31 Sequence control circuit 32 Transmit / receive signal switching circuit 33 Preamplifier 34 Time difference detection circuit 35 Vibration wave propagation speed setting device 36 Distance calculation circuit 37 Oscilloscope 101 Exploration object 102 Foreign matter 103 Defect 104 Bottom 41 Constant Voltage Source 42 Transistor 43 Freewheel Diode 51, 52 Transistor 53 High Voltage Power Supply 54 Transistor 55 Resistor 56 Diode 57 Regular Voltage Source 58 Freewheel Diode 59 Constant Voltage Diode 1 support piece 62 strain sensor 63 brake ring 64 cover 71 holding seat 72 piezoelectric element 91 of plastic film 92 pressure foot 93 first piezoelectric element 94 the second piezoelectric element

Claims (5)

[Claims] 1. A vibrating element driven by a giant magnetostrictive vibrating device in which the rising and falling characteristics of an exciting coil are highly responsive, and a passive damper or an active damper that acts in a vibrating direction and / or a direction perpendicular to the vibrating direction. Excitation coil auxiliary circuit or wave sensor for detecting the wave transmission signal of the vibrating element, and excitation coil auxiliary circuit or wave sensor for detecting the wave reception signal reflected from the bottom surface of the non-metallic material and / or its internal defect or buried foreign matter And a time difference detection circuit for detecting the time difference by comparing the waveforms of the transmitted signal and the received signal, and the thickness of the non-metal material from the time difference and the vibration wave propagation velocity of the non-metal material which is preset or measured. An inspection device for a thickness of a non-metal material, an internal defect, and a buried foreign matter, comprising: a distance calculation circuit that calculates a distance to a defect and a buried foreign matter. 2. An internal defect of a non-metallic material and a buried foreign matter, which are sequentially measured by a device of claim 1 from a plurality of different places, or simultaneously measured by using two or more sets of devices of claim 1. 2. An apparatus for investigating internal defects of non-metallic materials and buried foreign matter, comprising a position calculation circuit for synthesizing the respective distances to calculate a two-dimensional or three-dimensional position of the internal defect or buried foreign matter. 3. A voltage higher than usual is applied to the exciting coil at the moment when the current rises, and when the current reaches a target value, the current rising response is improved by switching to the normal voltage, and the exciting coil voltage is cut off. At the moment when the current drops, the low-voltage diode is connected in series with the freewheel diode on the power supply side of the transistor drive circuit to improve the current falling response, thereby performing pulse excitation for a short time on the giant magnetostrictive oscillator. An exploration device for a thickness of a non-metallic material and / or a foreign matter buried therein. 4. A vibrating wave is generated by using a vibration of a giant magnetostrictive element in a probing method for probing a thickness of a medium in which ultrasonic waves cannot be substantially propagated, a buried foreign substance in the medium, and an internal defect of the medium. Then, the vibration wave is transmitted toward the inside of the medium, the reflected wave is received, and the thickness of the medium, the foreign matter embedded in the medium, and the internal defect of the medium are searched. Characteristic exploration method. 5. An exploration method for exploring the thickness of a medium containing a conductive substance, the embedded foreign matter in the medium, and the internal defect of the medium, wherein a vibration wave is generated using vibration of a giant magnetostrictive element, The oscillatory wave is transmitted toward the inside of the medium, and the reflected wave is received to search for the thickness of the medium, the embedded foreign matter in the medium, and the internal defect of the medium. Exploration method.