JPH11248851A - Method and apparatus for detecting concealed metallic wire material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus whereby even an unskilled worker can easily detect a position of a concealed metallic wire material such as a reinforcing iron rod, an electric wire in a wall body, etc. SOLUTION: An a.c. magnetic field generated from a concealed metallic wire material is detected by a magnetic sensor(MI sensor) utilizing a magneto- impedance effect. A detecting apparatus 1 is provided with an MI sensor 10 and a vibrating device 20 such as a speaker or the like for vibrating the MI sensor 10. When the metallic wire material does not generate an a.c. magnetic field, an a.c. current is fed to the metallic wire material, e.g., electric wire, thereby generating the a.c. magnetic field, or the MI sensor is relatively vibrated to the metallic wire material, e.g., reinforcing iron rod, thereby turning the magnetic field generated from the reinforcing iron rod to be an a.c. If a plurality of MI sensors are arranged in parallel to each other, a position and a depth of the concealed metallic wire material can also be measured on the basis of a plurality of signals output from the MI sensors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a magnetic sensor (hereinafter referred to as MI sensor) utilizing a magneto-impedance effect, and is used in a wall (mortar, concrete), under a floor, under a metal panel, and insulated. Presence and position of metal linear materials such as iron, iron alloy, nickel, nickel alloy, cobalt, cobalt alloy, magnets, etc., concealed in the board or its back or in the ground, for example, electric wires, reinforcing bars, iron pipes, etc. And a method and apparatus for easily detecting the depth.

[0002]

2. Description of the Related Art Walls, pillars, ceilings and the like used for concrete structures such as buildings and bridges, and wooden structures such as houses.
When renovating floors, in order to prevent breakage of reinforcing bars, cutting of pipes and electric wires, non-destructive positions of internal reinforcing bars, metal pipes, and electric wires from surfaces such as walls, columns, ceilings, and floors It is necessary to accurately detect it. Therefore, conventionally,
By using a metal detector using a coil or a magnetic detector using a Hall element, an electromagnetic wave reflected from an embedded metal or a magnetic field from a reinforcing bar is detected to determine the presence and position of the metal.

[0003]

The metal detector used conventionally can detect the presence or absence of metal in concrete, but in recent years the wall may be covered with a metal panel or the like. It has become difficult to non-destructively detect steel bars, pipes, and electric wires. In addition, a magnetic detector using a Hall element can easily detect a magnetic substance that generates a strong magnetic field, but it is difficult to detect a normal reinforcing bar or the like due to other magnetic fields such as geomagnetism. There was a problem that only those who can use it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to use a small and high-sensitivity magnetic sensor to conceal rebars, electric wires, and the like in a wall. It is intended to detect the position of the metal wire that is being made, and to facilitate subsequent work such as renovation work, especially for metal wires that are easily concealed even by unskilled workers at the construction site. An object of the present invention is to provide a method for detecting a metal wire and a metal wire detecting device which is small and can be used easily.

[0005]

In order to achieve the above object, according to a basic aspect of the present invention, an AC magnetic field generated from a metal linear material concealed by a wall or the like is applied to an MI magnetic field.
There is provided a method for detecting a concealed metal linear material, wherein the detection is performed by a sensor, that is, a magnetic sensor utilizing a magneto-impedance effect. If an AC magnetic field is not generated from the concealed metal linear material itself, the AC magnetic field is forcibly generated and detected. In one embodiment, when the concealed metal wire is an electric wire, for example, an alternating current is passed through the metal wire (electric wire), and an AC magnetic field generated from the metal wire is detected by an MI sensor. To detect. In another aspect, the magnetic field generated from the metal linear material is converted into an alternating current by relatively vibrating the MI sensor with respect to the concealed metal linear material, and the alternating magnetic field is detected by the MI sensor. I do. In any of the above aspects, by arranging a plurality of MI sensors in parallel, based on a plurality of signals output from these MI sensors, not only the position of the concealed metal linear material but also the depth is measured. can do.

Further, according to the present invention, there is provided an apparatus for detecting a concealed metal linear material, comprising: the MI sensor described above; and a vibration device for vibrating the MI sensor. Provided. In a preferred embodiment that can measure the position and depth of the concealed metal linear material,
A plurality of the MI sensors are provided. Various linear actuators can be used as the vibration device. For example, in one embodiment, the vibration device includes a speaker and a non-magnetic coupling member that transmits vibration of a speaker cone of the speaker to the MI sensor. In the aspect, the rotary drive includes a rotary drive, and a link mechanism that converts the rotary motion of the rotary drive into a reciprocating motion and transmits the reciprocating motion to the MI sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for detecting a metal linear material according to the present invention uses 1 m as a means for detecting a concealed metal linear material.
It uses an MI sensor capable of detecting an AC magnetic field of Oe or less, and detects, for example, an AC magnetic field generated from an electric wire passing through a wall, and specifies the presence / absence and position (depth) of the electric wire. It is. By vibrating this sensor, a minute magnetic field emitted from a magnetic material such as a reinforcing bar in the wall is detected, and the presence or absence and position of the reinforcing bar in the wall are detected.

The MI sensor used in the present invention is based on a sensor principle in which a high-frequency current is applied to a magnetic wire or a magnetic thin film to cause a skin effect, thereby changing the impedance of the element by an external magnetic field. That is,
When a high-frequency small current is applied to a thin high-permeability magnetic material such as a Co-based amorphous wire, an amorphous ribbon, or an amorphous thin film, not only the inductance but also the electric resistance is simultaneously changed by the external magnetic field Hex due to the skin effect. The change in impedance due to this Hex (referred to as the magneto-impedance (MI) effect) changes the amplitude of the voltage between both ends of the thin high-permeability magnetic material sensitively, thereby forming a high-sensitivity magnetic sensor. This MI sensor does not require a head excitation coil and a detection coil required for a flux gate (FG) sensor, which is a conventional high-sensitivity magnetic sensor, and is easy to perform high-speed excitation with a small current compared to the FG sensor. Since the magnetic field coefficient is very small, there is an advantage that the decrease in the magnetic field detection sensitivity is small.
In addition, a conventional small sensor element, a magnetic resistance (MR)
The difference is that the device uses high-frequency current while the device uses direct current. In the AC (high-frequency) circuit technology, the resonance circuit can increase the magnetic field detection sensitivity of the MI element by several times. The MI sensor circuit uses a Colpitts oscillation circuit, and a high frequency inductance / capacitance resonance circuit can increase a voltage change of the MI head due to an external magnetic field with a sensitivity several times higher than the MI effect. Therefore,
A small, lightweight, high-sensitivity, low power consumption sensor circuit can be configured. Since the technology of the MI sensor itself is known, a detailed description thereof will be omitted.

As described above, since the MI sensor can detect only an AC magnetic field, even if the wall covering the metal linear material is covered with a metal such as copper or aluminum, the effect is not affected. , And is not affected by geomagnetism or other magnetism, and can identify the position of electric wires passing through the wall,
Further, by vibrating this sensor, the magnetic field emitted from a reinforcing bar, an iron pipe or the like can be converted into an alternating current, and only the magnetic field can be detected. In addition, in the metal wire detecting device using the MI sensor, since the device can be downsized, the device can be easily carried and used on a construction site.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be specifically described. FIG. 1 shows a basic configuration of a metal wire detecting device 1 of the present invention. As shown in FIG. 1, power is supplied to the MI sensor 10 and the vibration device 20 via a sensor signal processing circuit 11 and a vibration control circuit 21 by a power source 30 including a battery and a DC converter, respectively. For example, an alternating magnetic field generated from an electric wire through which an alternating current is passed is detected by the MI sensor 10 and sent to an output device 12 such as an LED or a buzzer through a sensor signal processing circuit 11, and visually and / or audibly. The position of can be confirmed. The vibration device 20 is connected so that the vibration can be transmitted to the MI sensor 10. For example, in the case of detecting a leakage magnetic field from a reinforcing bar or the like,
By operating the vibration device 20 whose vibration amplitude and frequency are controlled by the vibration control circuit 21, the MI sensor 1
0 and the distance between the object and the MI sensor 10
Can detect the AC component of the magnetic field. The on / off state of the vibration device is switched by a switch according to the test object. That is, when detecting an AC magnetic field generated from an electric wire, the vibration device 20 is turned off, and when detecting a leakage magnetic field from a reinforcing bar or the like, the vibration device 20 is turned on. As described above, the mode in which the power supply 11 is composed of a battery and a DC converter is suitably used in the case of a portable device, but the sensor signal processing circuit 11 and the vibration control circuit 21 are switched from an AC power supply through a power supply circuit. Can also be supplied with power.

2 and 3 show an embodiment of the metal wire detecting apparatus according to the present invention. FIG. 2 is a partially cutaway side view and FIG. 3 is a front view. A support plate 41 is attached to a substantially central portion of the housing 40 of the apparatus 1a, and a non-magnetic arm 43 such as an acrylic resin is slidably disposed in a central hole 42 of the support plate 41. I have. An MI sensor 10a and a sensor signal processing circuit 11a are attached to a front end of the arm 43, and a rear end is connected to a speaker cone (not shown) of a speaker 20a as a sensor vibration device. Accordingly, when the speaker 20a is operated, the vibration of the speaker cone is caused by the arm 4
3, the MI sensor 10a can be oscillated at a predetermined amplitude (preferably about 5 to 8 mm) and frequency (preferably about 10 Hz). Also, the MI sensor 10 on the lid 44 of the housing 40
A sensor center mark 45 is provided at a position matching with a.

A circuit housing box 46 for housing the vibration control circuit 21a is mounted on the rear bottom surface of the housing 40. A grip 47 is provided on the bottom surface of the circuit storage box 46, and the transformer 22 and the power supply circuit 23 are provided on the rear end surface.
A circuit storage box 48 for storing the. One end of another substantially L-shaped grip 49 is fixed to the upper surface of the rear end of the housing 40, and the other end is fixed to the upper rear side of the circuit housing box 48.
An output device (meter) 12a and a measurement on / off switch 50 are attached to the upper part of the device. Reference numeral 24 denotes a fuse mounting portion, 25 denotes a cord connected to a power supply circuit, 26
Is a vibration on / off switch, and 27 is an outlet.
The alternating current supplied from the power supply is processed by the power supply circuit 23, and the current of +7 V is converted to the sensor signal processing circuit 11a.
, And a current of ± 15 V is supplied to the vibration control circuit 21a, but the electrical wiring is omitted for convenience of illustration.

In using the above device, first, the outlet 27 is inserted into a power plug (not shown), the measurement on / off switch 50 is turned on, and then, for example, the sensor center mark 45 is brought close to or in contact with the wall. Then, the device is moved along the wall, and the work of detecting metal wires such as electric wires and reinforcing bars is started. When an object that generates an AC magnetic field, such as an electric wire, is detected, the detection can be performed only by bringing the sensor center mark 45 (sensor unit) close to the test object while the vibration on / off switch 26 is turned off. On the other hand, when detecting a magnetic object such as a reinforcing bar, the detection operation is performed while the vibration on / off switch 26 is turned on and the speaker 20 is operated to vibrate the MI sensor 10a. One of the features of the device for detecting a metal linear material such as a reinforcing bar or an electric wire in a wall of the present invention is that two types of test objects (for example, (Electric wires under load and rebar with magnetism).

FIG. 4 shows another embodiment of the metal wire detecting device according to the present invention. A housing 6 extending horizontally from the lower front end of an output display box 61 of the device 1b.
On the upper surface of the base plate 62, a guide rail 63 is fixed, in which a plurality of guide pins 64 are provided at predetermined intervals in two rows on the left and right so as to project at a predetermined interval between each row. The slider 65 is located at the center of the lower surface in the longitudinal direction,
It has a guide member 66 disposed between the two rows of guide pins 64 on the left and right, and is slidably disposed on the guide rail 63. The MI sensor 10b and the sensor signal processing circuit 11b are attached to the tip of the slider 65, and the rear end of the guide member 66 is connected to a link 67.
Is pivotally attached to the tip of the
The rear end of the link 67 is pivotally attached via a pin 69 to a peripheral portion of a rotating disk 70 fixed to a rotating shaft 72 of a motor 71 housed in a grip 73. Reference numeral 74 denotes a power switch. Note that an external power supply may be used as the power supply, or a battery and a DC converter may be housed in the grip 73. In addition, as a material of the guide rail 63, the guide pin 64, the slider 65, the guide member 66, the link 67, and the like, a non-magnetic material is preferable. In addition, electric wiring is omitted for convenience of illustration.

In this apparatus, a motor 71 is driven to rotate a rotary plate 70 fixed to a rotary shaft 72, so that the rotary motion is converted into a linear motion by a link 67, and a slider 65 and a Sensor 10b and sensor signal processing circuit 1 attached to
1b is vibrated. Thereby, the magnetic field emitted from the reinforcing bar or the like in the wall body can be converted into an alternating current and detected. When detecting an AC magnetic field generated from an electric wire in which an AC current is flowing, the vibration ON / OFF switch (not shown) is kept in an OFF state as in the apparatus shown in FIGS. use.

Hereinafter, some examples in which the effects of the present invention have been specifically confirmed will be described below. Example 1 Between the metal wire detecting device 1a shown in FIGS. 2 and 3 whose schematic configuration and device dimensions are shown in FIG.
As shown in FIG. 6, a shield 80 made of a wooden or concrete plate having a different thickness is placed, and an alternating current (100
(V, 50 Hz) was detected. The electric wire 90 has a power of 25 to 1,14.
Electricity was supplied up to 0W. In this embodiment, the electric wire 90 to be detected is connected to a heater or the like, and a load is applied to pass electricity. FIG. 7 shows the relationship between the distance between the MI sensor and the electric wire and the output of the MI sensor with respect to the electric power flowing through the electric wire.
Shown in In addition, as shown in Table 1 below, electric wires were similarly detected using shields 80 of various materials and plate thicknesses. The evaluation results are also shown in Table 1.

[Table 1]

As is apparent from the results shown in FIG.
Even when a load of about W is applied, a magnetic field of 1 mOe or more sufficient for output to an LED or a buzzer can be detected at a position about 10 mm away. In addition, when electricity of 400 W or more is supplied to the electric wire, a magnetic field of 6 mOe or more is detected even at a distance of about 100 mm, and is output to an LED, a buzzer, or the like, and the presence or absence and position of the electric wire can be determined. Also, as shown in Table 1, when a shield made of an iron plate or a magnetic powder (ferrite) is arranged between the electric wire and the MI sensor, the wire cannot be detected, but the material of the shield is In the case of wood, concrete, stone, aluminum, and copper, a magnetic field of 1 mOe or more is detected, and electric wires can be detected without problems on walls, ceilings, and floors where ordinary construction is performed. Also,
In actual construction, since the electric wire is often housed in a protective iron pipe, it is possible to detect the electric wire by using the method of detecting a reinforcing bar shown in the following second embodiment.

Example 2 An apparatus as shown in FIGS. 2, 3, and 5 was used to vibrate an MI sensor, detect a change in a magnetic field, and detect a reinforcing bar. The MI sensor 10a and the sensor signal processing circuit 11 are controlled by the vibration device (speaker) 20a.
a was vibrated in the front-back direction at a frequency of about 10 Hz and an amplitude of 8 mm. Even though the magnetic field emitted from the rebar is constant, the distance from the rebar changes because the MI sensor vibrates, and the magnetic field changes.
The MI sensor senses the change, converts it into an electric signal in the sensor signal processing circuit 11a, sends this signal to the output device 12a, and detects the presence or absence and position of the reinforcing bar. As a detection target, an iron rod having a diameter of 7 mm or 5 mm and an iron pipe having a diameter of 10 mm or 12 mm were used. FIG. 8 shows the result.
When the change in the magnetic field generated from the iron bar or the iron pipe when the distance between the iron bar or the iron pipe and the MI sensor was changed was examined, as shown in FIG. 8, if the distance was at least about 50 mm, It was confirmed that a magnetic field of 1 mOe or more could be detected, and the presence or absence and position of a reinforcing bar under the ceiling, wall, or floor could be detected.

Embodiment 3 By the method as in Embodiments 1 and 2, the presence / absence and position of the rebar can be detected, but it is also necessary to know the depth from the wall surface. Therefore, as shown in FIG. 9, two MI sensors 10a (1) and 10a (2) are used, one of them is placed at the position where the magnetic field is strongest, and the two MI sensors 10a (1) at that time are used. From the strength of each magnetic field detected by 10a (2), the depth of the position of the reinforcing bar 91 from the surface of the wall 81 was obtained. In the method, first, as shown in FIG. 10, the reinforcing bar 91 and the detection device 1c are arranged. At this time, the metal wire detector is arranged so that the MI sensor 10a (1) displays the strongest magnetic field, and the depth of the reinforcing bar 91 is determined from the difference in the signals of the MI sensors 10a (1) and 10a (2) at that time. Digitally. At this time, the magnetic fields read by the MI sensors 10a (1) and 10a (2) are H ₁ and H ₂ , the distance between the MI sensors 10a (1) and 10a (2) is X ₃ , and the MI sensor 10a (1)
The distance to the rebar 91 When X ₁ from the distance between the MI sensor 10a (2) and the reinforcing bar 91 X ₂ becomes, X ₁ <
In X _2, detecting the magnetic field of the MI sensor 10a (2) is weakened. Since the magnetic field detected by the MI sensors 10a (1) and 10a (2) is only the component in the vibration direction, each of X ₁ , X ₂ , X
₃ and the magnetic fields H ₁ and H ₂ have the following relationship. Since X ₃ is a constant, if H ₁ and H ₂ are known, the depth X _{1 of the} reinforcing bar can be obtained. ^{_{X 2 2 = X 1 2 +}} X 3 2 H 1 X 1 3 = H 2 X 2 3

The MI sensor 1 uses a reinforcing bar having a diameter of 7 mm.
Table 2 below shows the results of measurement by the above-mentioned method with the distance between 0a (1) and 10a (2) set to 50 mm.

[Table 2] As shown in Table 2, the rebar placed at a predetermined depth could know the depth within an error range of about 10% if it was a depth of up to about 100 mm. Note that three or more MI sensors can be used to reduce the measurement error.

[0021]

As described above, the method and apparatus of the present invention for detecting a metal wire concealed by a wall, a floor, a ceiling, a panel, etc., such as a reinforcing bar and an electric wire in a wall, are provided. Not only can it easily detect the presence or absence and position of electric wires in ceilings and floors, but also can detect with high sensitivity the presence, location, and depth of reinforcing bars in concrete surrounded by metal panels such as aluminum. It also has the advantage of being very compact and easy to use on site.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of an apparatus for detecting a concealed metal wire according to the present invention.

FIG. 2 is a schematic partial cross-sectional side view of one embodiment of the metal wire detecting device of the present invention.

FIG. 3 is a front view of the device shown in FIG. 2;

FIG. 4 is a schematic perspective view of another embodiment of the metal wire detecting device of the present invention.

FIG. 5 is a schematic configuration diagram illustrating a dimensional relationship of the metal wire rod detecting device used in the first embodiment.

FIG. 6 is a partial schematic cross-sectional view showing an arrangement relationship between a test object and an MI sensor of the metal wire detecting device in the first embodiment.

FIG. 7 is a graph showing the relationship between the distance between the electric wire and the MI sensor measured in Example 1 and the detected magnetic field.

FIG. 8 is a graph showing a relationship between a distance between an iron bar or an iron pipe and an MI sensor measured in Example 2 and a detected magnetic field.

FIG. 9 is a schematic configuration diagram of a metal wire detecting device used in a third embodiment.

FIG. 10 is a partial schematic cross-sectional view showing an arrangement relationship between a test object and an MI sensor of a metal wire rod detecting device according to a third embodiment.

[Explanation of symbols]

1, 1a, 1b, 1c Metal wire detection device 10, 10a, 10b, 10a (1), 10a (2)
MI sensor 11, 11a, 11b, 11a (1), 11a (2)
Sensor signal processing circuit 12, 12a Output device (meter) 20 Vibration device 20a Speaker 21, 21a Vibration control circuit 22 Transformer 23 Power supply circuit 26 Vibration on / off switch 30 Power supply 40, 60 Housing 43 Arm 45 Sensor center mark 47, 49 , 73 Grip 50 Measurement on / off switch 63 Guide rail 65 Slider 67 Link 70 Turntable 71 Motor 80, 81 Shield (wall) 90 Electric wire 91 Iron rod or iron pipe

Claims (8)

[Claims] 1. A method for detecting a concealed metal wire, comprising detecting an AC magnetic field generated from the concealed metal wire by a magnetic sensor utilizing a magneto-impedance effect. . 2. An concealed metal wire, wherein an AC current is passed through the metal wire, and an AC magnetic field generated from the metal wire is detected by a magnetic sensor utilizing a magneto-impedance effect. Method of detecting metal linear material. 3. A magnetic field generated from the metal linear material is converted into an alternating current by vibrating a magnetic sensor utilizing a magneto-impedance effect relative to the concealed metal linear material, and the alternating magnetic field is reduced. A method for detecting a concealed metal linear material, wherein the method is performed by the magnetic sensor. 4. A method comprising: arranging a plurality of magnetic sensors in parallel, and measuring a position and a depth of the concealed metal linear material based on a plurality of signals output from the magnetic sensors. The method according to claim 1, wherein the method comprises: 5. An apparatus for detecting a concealed metal linear material, comprising: a magnetic sensor using a magneto-impedance effect; and a vibrating device for vibrating the magnetic sensor. 6. The apparatus according to claim 5, comprising a plurality of said magnetic sensors. 7. The device according to claim 5, wherein the vibration device includes a speaker and a non-magnetic coupling member that transmits vibration of a speaker cone of the speaker to the magnetic sensor. 8. The vibration device according to claim 5, wherein the vibrating device includes a rotary driving device, and a link mechanism that converts a rotary motion of the rotary driving device into a reciprocating motion and transmits the reciprocating motion to the magnetic sensor.
An apparatus according to claim 1.