JPH06281628A - Flaw detecting sensor of remote field eddy-current flaw detection device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of noise signals against defect signals in a remote field eddy current flaw detection device. CONSTITUTION:In a remote field eddy current flaw detection device which detects an objective point by running a flaw detecting sensor in which a transmission unit 1 with a transmission coil 3 and reception unit 4 (4a and 4b) with reception coils 6 are coupled with each other at a prescribed distance through a coil spring and a signal line and rope, etc., 18 are stretched inside the spring 7 in a pipe buried in the ground, the spring 7 is constituted of a nonmagnetic elastic material and, at the same time, the rope, etc., 18 are constituted of a nonmetallic material. Therefore, the occurrence of noise signals which are generated when electromagnetic waves propagated to the reception coil 6 from the transmission coil 3 pass through the coil 7 and noise signals which occur when a current is induced in a tensile member by external electromagnetic waves can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw detection sensor of a remote field eddy current flaw detection device for inspecting the corrosion state of underground pipes such as city gas supply pipes.

[0002]

2. Description of the Related Art A remote field eddy current flaw detector is one of the flaw detectors for inspecting the corrosion state of underground pipes and detecting joints.

This flaw detection apparatus has a flaw detection sensor constructed by connecting a common transmission unit having a transmission coil and an appropriate number of reception units having a reception coil with a predetermined distance, and connecting them through a coil spring. It is composed of a drive cable connected to the sensor, a drive mechanism for the drive cable, and a flaw detection device body that transmits and receives signals to and from the flaw detection sensor to process signals. Then, the flaw detection sensor is driven in the underground pipe by a distance-measuring drive mechanism, and changes in the propagation time of the electromagnetic wave from the transmitting coil to the receiving coil cause defects such as corrosion wall thinning and through holes, or target points such as joints. In addition to the detection, the position of the target point such as the defect is measured by the traveling distance of the flaw detection sensor. At this time, the change in the propagation time appears as a phase difference between the reception signal and the transmission signal, and this phase difference is detected by using a lock-in amplifier or the like.

The coil spring keeps the transmitting unit and the receiving unit at a predetermined distance and, because of its flexibility, enables the underground buried pipe to move smoothly in the curved pipe portion. In order to prevent permanent deformation and increase rigidity, a steel wire as a tension member is stretched over a predetermined distance inside the coil spring. For this reason, the transmission unit and the reception unit are configured to be hollow in the axial direction, and the signal wire and the steel wire as a tension member connected to each unit are penetrated through the hollow portion.

[0005]

The coil spring, including the one between the transmitting unit and the receiving unit, is made of ordinary spring steel, and is therefore a magnetic body, so that the electromagnetic wave from the transmitting coil to the receiving coil is absorbed. Some pass through the coil spring. For this reason, this becomes a noise signal, which is one of the causes of deteriorating the discriminability of the defect signal to be detected.

On the other hand, since the steel wire stretched as a tensile member has conductivity, a current is induced in this steel wire by an electromagnetic wave from the outside, and the magnetic field due to this induced current also becomes a noise signal for detection. This is one of the causes of deteriorating the discriminability of defective signals to be processed. Therefore, the present invention aims to eliminate such factors.

[0007]

In order to solve the above-mentioned problems, according to the present invention, a transmission unit provided with a transmission coil and a reception unit provided with a reception coil are connected via a coil spring at a predetermined distance. At the same time, in a remote field eddy current flaw detector that detects a target location by running a flaw detection sensor in which a signal wire and a tension member are stretched in the coil spring inside an embedded pipe, the flaw detection sensor uses a non-magnetic elastic body for the coil spring. Suggest to configure.

Further, the present invention, as the next means for solving the above-mentioned problems, connects a transmission unit provided with a transmission coil and a reception unit provided with a reception coil with a predetermined distance therebetween via a coil spring. , In a remote field eddy current flaw detection device that detects a target location by running a flaw detection sensor in which a signal wire and a tension member are stretched in a coil spring inside an embedded pipe, the flaw detection sensor has a tension member made of a non-metal body. I suggest that.

Further, according to the present invention, the transmission unit provided with the transmission coil and the reception unit provided with the reception coil are connected via a coil spring at a predetermined distance, and a signal line and a tension member are stretched in the coil spring. In a remote field eddy current flaw detection device that detects the target location by running the flaw detection sensor installed inside the buried pipe, the flaw detection sensor must have a coil spring made of a non-magnetic elastic body and a tensile member made of a non-metal body. To propose.

In the present invention, it is proposed that the nonmagnetic elastic body is a copper-based spring material such as beryllium copper or phosphor bronze.

Further, the present invention proposes that, in the above-mentioned constitution, the non-metal body is a fiber having high strength and high elastic modulus such as aramid fiber.

[0012]

When the coil spring is made of a non-magnetic material, electromagnetic waves from the transmitting coil to the receiving coil do not pass through the coil spring but efficiently pass through the pipe wall of the target underground pipe. As described above, it is possible to prevent the generation of a noise signal due to the electromagnetic wave passing through the coil spring.

When the tension member is made of a non-metallic material, an induction current due to an electromagnetic wave from the outside does not occur, and it is possible to prevent the generation of a noise signal due to this induction current.

[0014]

Embodiments of the present invention will now be described with reference to the accompanying drawings. In the figure, reference numeral 1 is a transmitting unit, and the transmitting unit 1 has a diameter smaller than that of a target underground buried pipe (not shown), and a transmitting coil is provided in a hollow vessel body 2 which is movable even in a curved pipe portion. 3 is provided, and the transmitter coil 3
The winding axis direction of corresponds to the axial direction of the underground buried pipe.

Reference numeral 4 is a receiving unit, and the receiving unit 4 (4a, 4b) is provided corresponding to each of the front side and the rear side of the transmitting unit 1. As in the hollow vessel 2, each receiving unit 4 has a plurality of receiving coils around the hollow vessel 5 that has a smaller diameter than the target underground buried tube and is movable even in a curved pipe section. 6 is provided, and the winding axis direction of each receiving coil 6 corresponds to the radial direction of the underground buried pipe.

Threaded portions 8 of the coil spring 7 are formed at both ends of the hollow portions of the hollow vessels 2 and 5, respectively.
After the coil springs 7 are screwed into each other and then hardened with silicone resin or the like, the hollow vessel bodies 2 and 5 are connected to the coil springs 7. Of course, the connection method is not limited to this. In this way, the receiving units 4a, 4 are separated by a predetermined distance by the coil springs 7 on both the front side and the rear side of the transmitting unit 1.
b is connected. The material of these coil springs 7 is beryllium copper. If the coil spring 7 is made of a non-magnetic elastic material as described above, another copper-based spring material such as phosphor bronze can be used.

A support 9 for holding the coil spring 7 at the center of the underground pipe is provided in the middle of the coil spring 7. This support body 9 has sliding members 11 fitted on both sides of a stopper cylinder 10 fixed to a coil spring 7, and is bent outward between these sliding members 11 so as to be entirely buried in the underground pipe. This is a configuration in which the leaf spring 12 configured to be larger than the inner diameter of is provided. The support 9 holds the coil spring 7 at the center by elastically pressing the leaf spring 12 against the inner wall of the underground pipe.

On the other hand, a tip guide body 13 is formed in front of the front receiving unit 4a, and a normal spring steel is used between the tip guide body 13 and the receiving unit 4a by the same connection method as described above. The constructed coil springs 14 are connected. The support 9 is also provided in the middle of the coil spring 14.

Also, one end of a coil spring 15 made of ordinary spring steel is connected to the rear side of the rear receiving unit 4b by the same connecting method as described above, and the other end of this coil spring 15 is connected. It is connected to a connection support body 17 for connection with the drive cable 16. The support 9 is also provided in the middle of the coil spring 15.

Between the connection support body 17 and the tip guide body 13,
A rope (or wire) 18 is stretched as a tension member, and the rope 18 and the like 18 are coil springs 7, 14, 1.
5 and the center of the hollow portion of the hollow container body 2, 5. The rope 18 and the like are made of high-strength and high-modulus fibers such as aramid fibers.

The coil springs 7 and 15 and the hollow container bodies 2 and 5
Signal wires 19 (19a, 19b) connected to the transmitting coil 3 and the receiving coil 6 are inserted in the hollow portion of the above, and these are arranged around the rope 18 and the like.

[0022]

As described above, the present invention has the following effects. It is possible to prevent a noise signal from being generated due to the electromagnetic waves from the transmitting coil to the receiving coil passing through the coil spring. It is possible to prevent a noise signal from being generated due to an electric current being induced in the tensile member by an external electromagnetic wave.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing a flaw detection sensor portion of a remote field eddy current flaw detection apparatus to which the present invention is applied.

FIG. 2 is an enlarged view of a receiving unit portion of FIG.

3 is a cross-sectional view taken along the line AA of FIG. 2 (or FIG. 1).

FIG. 4 is a sectional view taken along line BB in FIG.

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

6 is a cross-sectional view taken along the line DD of FIG.

[Explanation of reference symbols] 1 transmitter unit 2 hollow container 3 transmitter coil 4 (4a, 4b) receiver unit 5 hollow container 6 receiver coil 7 coil spring 8 screwing portion 9 support body 10 stopper cylinder body 11 sliding member 12 plate Spring 13 Tip guide body 14 Coil spring 15 Coil spring 16 Drive cable 17 Connection support body 18 Rope etc. 19 (19a, 19b) Signal line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Suyama 1-15-8 Kataseyama, Fujisawa City, Kanagawa Prefecture (72) Inventor Satoshi Suzuki, 3303-345 Shiomidai, Isogo-ku, Yokohama City, Kanagawa Prefecture (72) Inventor Naoki Taoka Hyogo 1-11-2-610 Sakasedai, Takarazuka-shi, prefecture (72) Inventor Jun-ichi Ando 2-41, Torakeiyama-cho, Tajimi-shi, Gifu (72) Inventor Masayuki Ishikawa 16-13 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi (72) Inventor Kimio Nakajima 4-53-3 Kitahama, Chuo-ku, Osaka-shi, Osaka

Claims (8)

[Claims] 1. A flaw detection sensor in which a transmission unit provided with a transmission coil and a reception unit provided with a reception coil are connected via a coil spring at a predetermined distance, and a signal line and a tension member are stretched in the coil spring. In a remote field eddy current flaw detector for detecting a target location by running a pipe inside a buried pipe, a flaw detection sensor for the remote field eddy current flaw detector characterized in that a coil spring is made of a non-magnetic elastic body. 2. A flaw detection sensor in which a transmission unit provided with a transmission coil and a reception unit provided with a reception coil are connected via a coil spring at a predetermined distance, and a signal line and a tension member are stretched in the coil spring. In the remote field eddy current flaw detector, which detects the target location by running the inside of the buried pipe, the flaw detection sensor of the remote field eddy current flaw detector characterized in that the tension member is made of a non-metal body. 3. A flaw detection sensor in which a transmission unit provided with a transmission coil and a reception unit provided with a reception coil are connected at a predetermined distance via a coil spring, and a signal line and a tension member are stretched in the coil spring. In a remote field eddy current flaw detector for detecting a target location by running a pipe inside an embedded pipe, the remote field eddy current characterized in that the coil spring is made of a non-magnetic elastic body and the tension member is made of a non-metal body. Flaw detection sensor for flaw detection equipment 4. The flaw detection sensor for a remote field eddy current flaw detection device, wherein the non-magnetic elastic body according to claim 1 or 3 is a copper spring material. 5. The flaw detection sensor for a remote field eddy current flaw detection apparatus, wherein the copper-based spring material according to claim 4 is beryllium copper. 6. A flaw detection sensor for a remote field eddy current flaw detection device, wherein the copper-based spring material according to claim 4 is phosphor bronze. 7. A flaw detection sensor for a remote field eddy current flaw detection device, wherein the non-metal body according to claim 2 or 3 is composed of high-strength and high-modulus fibers 8. The flaw detection sensor for a remote field eddy current flaw detection device, wherein the high-strength, high-modulus fiber of claim 7 is an aramid fiber.