JP3180853B2 - Receiving unit in remote field eddy current type flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving unit in a remote field eddy current type flaw detector for inspecting a corrosion state of a buried pipe such as a city gas supply pipe.

[0002]

2. Description of the Related Art There is a remote field eddy current type flaw detector as one of flaw detectors for inspecting the state of corrosion of buried piping and detecting joints and the like.

In this flaw detection device, 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 is traveled in a buried pipe by a traveling device capable of measuring a distance, and transmitted. In addition to detecting a target such as corrosion thinning or a defect such as a through hole or a joint or the like based on a change in the propagation time of the electromagnetic wave from the coil to the receiving coil, and measuring the position of the target or the like based on the traveling distance of the flaw detection sensor. Things. At this time, the change in the propagation time appears as a phase difference between the reception signal and the transmission signal, and the phase difference is detected using a lock-in amplifier or the like.

In such an apparatus, a single transmitting coil is used, but a receiving coil does not hinder the flow of gas in the pipe, and can detect a local defect on the inner wall of the pipe with as high a resolution as possible. In order to achieve this, a plurality are arranged in a ring.

[0005] Since the transmitting coil may be separated from the tube wall in the principle of the remote field eddy current type flaw detector, the outer diameter of the transmitting unit is set to improve the insertion property in the curved tube portion.
It is configured to be about 75% of the inner diameter of the tube.

However, the receiving coils arranged annularly in the receiving unit cannot obtain sufficient sensitivity unless they are brought as close as possible to the tube wall. Therefore, the receiving coils are attached to the inner wall of the buried pipe in a radial direction so as to be pressed against and tightly attached to the inner wall. The contact piece has a biased elasticity. That is, in this configuration, the contact piece comes into close contact with the inner wall of the buried pipe by its own elastic force as described above, thereby bringing the receiving coil close to the inner wall,
An obstacle such as a protrusion on the inner wall of the buried pipe or a difficult-to-pass portion such as a curved pipe portion can pass through by being deformed in the centripetal direction.

[0007]

As described above, in the structure of the receiving unit which can be brought into close contact with the tube wall by using only the elasticity of the contact piece itself or can be passed by elastic deformation at a place where insertion is difficult, If the elastic force to the wall is increased and the adhesion to the tube wall is improved, the mobility at obstacles, particularly at the curved pipe portion, becomes worse.If the elastic force is reduced to improve the mobility, There is a problem that the adhesion is deteriorated.
An object of the present invention is to solve such a problem.

[0008]

In order to solve the above-mentioned problems, according to the present invention, in a buried pipe, a flaw detection sensor in which a transmitting unit provided with a transmitting coil and a receiving unit provided with a receiving coil are connected at a predetermined distance is provided. In the remote field eddy current type flaw detection device that detects the target location by traveling to the receiving unit, the receiving unit elastically attaches a large number of contact pieces that are long in the moving direction on the outer circumference of the body connected to the transmitting unit etc. We propose a receiving unit in a remote field eddy current type flaw detector that is supported movably inward and outward by a support rod that can be extended and retracted, and has a receiving coil installed on each contact piece.

The present invention also proposes that in the receiving unit having the above-mentioned structure, the receiving coil is installed with the winding axis directed in the radial direction of the body.

Further, in the present invention, in the receiving unit having the above structure, the support rod which can be elastically extended and contracted is used as an operating rod of a pneumatic cylinder device, and an air communication space for distributing air to each pneumatic cylinder device is provided as a body. We propose to configure

In the present invention, it is proposed that the support rods of the adjacent contact pieces are arranged in a staggered manner in the receiving unit having the above configuration.

Further, in the present invention, it is proposed that the contact piece is made of a synthetic resin such as a polyacetal resin and the both ends are curved inward in the receiving unit having the above structure.

[0013]

When the receiving unit is moved into the buried pipe, the support rod is driven in the extending direction. Then, a large number of contact pieces move in the radial direction and elastically press against the inner wall of the buried pipe,
Since the receiving coil provided on this contact piece is close to the inner wall,
A sufficient receiving sensitivity can be obtained.

In such a state, if the receiving unit reaches an obstacle such as a protrusion while moving the straight pipe portion of the buried pipe,
The contact piece moves in the centripetal direction while elastically shortening the support rod by the obstacle, so that the receiving unit can move through the obstacle.

When the receiving unit reaches the bent portion of the buried pipe, all the support rods are driven in the shortening direction. By doing so, all the contact pieces move in the centripetal direction, and the outer diameter of the receiving unit as a whole becomes smaller than the inner diameter of the buried pipe, so that it can easily pass through even a curved pipe portion.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the appearance of a remote field eddy current type flaw detector to which the present invention is applied, and FIG. 2 is an enlarged view of a part of the flaw detection sensor 1 in FIG. Reference numeral 1 denotes a flaw detection sensor. The flaw detection sensor 1 is configured by connecting a transmission unit 2 provided with a transmission coil (not shown) and a reception unit 4 provided with a reception coil 3 with a coil spring 5 at a predetermined distance. Make up. A drive wheel 7 driven by a geared motor 6 is connected to the front of the transmission unit 2 of the flaw detection sensor 1 and a camera head 8 is provided at a tip end thereof. are doing. Code 9
Are connectors provided at both ends of the flaw detection sensor 1. The connectors are configured to supply power, communicate, and supply air, which will be described later, from a cable 10 via the connector 9. Connected to controller 12. Under the control of the personal computer 13, the controller 12 supplies power from a power supply (not shown), relays communication between the personal computer 13 and the flaw detection sensor 1 and the camera head 8, and supplies air from the compressor 14. Is performed.

As described above, the flaw detection sensor 1 is constituted by connecting the transmitting unit 2 and the receiving unit 4 at a predetermined distance by the coil spring 5, and a centering support 15 is provided at an intermediate portion. ing.

FIG. 3 is a longitudinal sectional view of a part of the receiving unit 4.
4 and 5 are a longitudinal sectional view and a transverse sectional view, respectively, of the body 16 constituting the receiving unit 4. FIG.
It is a perspective view of the contact piece 17 which comprises.

The body 16 is formed as a hollow body provided with a through-hole 17, and a cylindrical body 18 for passing a power supply or communication cable is mounted in the through-hole 17.
A gap is provided between the outer wall of the cylindrical body 18 and the inner wall of the through hole 17, and the gap forms an air communication space 19. The air communication space 19 is configured as a sealed space by a seal member 20 provided between the outer wall of the cylindrical body 18 and the inner wall of the through hole 17. An air supply hole 21 communicating with the air communication space 19 is formed on one side of the body 16.
4 is connected to the air supply pipe 22.

Driving holes 23 are formed in the body 16 radially. The inner ends of the driving holes 23 open in the through holes 17 and the outer ends of the driving holes 23 extend outside the body 16. It is open. These drive holes 23 are arranged in a zigzag pattern so that the ones adjacent to each other in the rotational direction are positioned at the top and bottom in FIG.

An operating rod 24 is fitted in the driving hole 23 so as to be movable inward and outward, and an O-ring 25 is
The operating rod 24 is moved outward by the air pressure of the air communication space 19 and is moved inward by the return spring 26. That is, the driving hole 23 and the operating rod 24 constitute a cylinder device.

A contact piece 27 which is long in the moving direction of the receiving unit 4 is fixed to the distal end of the operating rod 24. Therefore, the contact piece 27 is annularly disposed around the body 16. Each contact piece 27 is made of a material such as polyacetal resin, which is easily slipped between metals, and both ends are curved inward.

A circular recess 28 which is open outward is formed in the middle of the contact piece 27, and the receiving coil 3 is mounted in the circular recess 28, and the cover 29 prevents falling off. As described above, the winding axis of the receiving coil 3 is oriented in the radial direction of the body 16. The contact piece 27 has a circular recess 28.
A wiring path 34 is formed from the wiring to the one end side, and the wiring of the receiving coil 3 passes through the wiring path 34.

Reference numeral 30 denotes an end member fixed to one side of the body 16 with bolts 31. The end member 30 has a cylindrical structure on one end side and a cable passing therethrough. The connection coil spring 5 described above is mounted on the outside of the. On the other side of the container 16, a cylinder 18
The coupling coil spring 5 is attached to the outside of the end of the connection.

In the above configuration, when pressurized air is supplied from the air supply pipe 22 to the air communication space 19 through the air supply hole 21, the operating rod 24 moves outwardly against the bias of the return spring 26. Therefore, the contact piece 27 annularly disposed on the outer periphery of the body 16 is moved in the radial direction.

Therefore, in the buried pipe 33, a large number of contact pieces 27 arranged in an annular shape are elastically pressed against the inner wall of the buried pipe 33 by air pressure, and a receiving coil provided at an intermediate portion of the contact piece 27 is provided. Since 3 is close to the inner wall, sufficient receiving sensitivity can be obtained. Further, since the receiving coil 3 has a winding axis oriented in the radial direction of the body 16, the cylindrical body 18
The influence of the magnetic field generated by the current flowing through the power supply and communication cables passing in the axial direction of the body 16 in the inside is avoided.

Since the large number of contact pieces 27 are elastically pressed against the inner wall of the buried pipe 33 by air pressure, when the receiving unit 4 is moving along the straight pipe of the buried pipe 33 in such a state. When the contact piece 27 reaches an obstacle such as a protrusion, the contact piece 27 moves in the centripetal direction while elastically shortening the operation rod 24 by the obstacle, so that the receiving unit 4 can move through the obstacle. Each of the contact pieces 27 is made of a material such as polyacetal resin which is easily slipped between metals, and both ends are bent inward. As a result, it is possible to prevent the passage in the buried pipe 33 from being deteriorated.

When the receiving unit 4 reaches the bent portion of the buried pipe 33, when the supply of the pressurized air through the air supply pipe 22 is stopped, all the operating rods 24 are returned to the return springs 26.
Of the receiving unit 4 is moved in the centripetal direction, and the outer diameter of the receiving unit 4 as a whole is smaller than the inner diameter of the buried pipe 33. Will be able to pass through.

[0029]

As described above, in the present invention, the receiving coil can be elastically brought close to the inner wall of the buried pipe in the flaw detection to obtain a sufficient receiving sensitivity, and at the same time an obstacle, especially a curved pipe portion can be obtained. There is an effect that mobility is good.

[Brief description of the drawings]

FIG. 1 is an external explanatory view of a remote field eddy current type flaw detector to which the present invention is applied.

FIG. 2 is an enlarged view of a flaw detection sensor part of FIG.

FIG. 3 is a longitudinal sectional view of a receiving unit of the present invention.

FIG. 4 is a longitudinal sectional view of a container constituting the receiving unit of the present invention.

FIG. 5 is a transverse sectional view of a body constituting the receiving unit of the present invention.

FIG. 6 is a perspective view of a contact piece constituting the receiving unit of the present invention.

FIG. 7 is a longitudinal sectional view showing the operation of the receiving unit of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 flaw detection sensor 2 transmitting unit 3 receiving coil 4 receiving unit 5 coil spring 6 motor with gear 7 drive car 8 camera head 9 connector 10 cable 11 cable drum 12 controller 13 personal computer 14 compressor 15 support 16 body 17 contact piece 18 tube Body 19 Air communication space 20 Sealing material 21 Air supply hole 22 Air supply pipe 23 Drive hole 24 Operating rod 25 O-ring 26 Return spring 27 Contact piece 28 Circular recess 29 Cover 30 End member 31 Bolt 32 Cylindrical member 33 Buried tube 34 Wiring path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 27/72-27/90 G01N 29/00-29/28

Claims (6)

(57) [Claims] 1. A remote field eddy current type flaw detection device for detecting a target location by running 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 through a buried pipe. In the receiving unit, the outer periphery of the body connected with the transmitting unit, etc.,
A remote field eddy current flaw detection device characterized in that a large number of contact pieces that are long in the moving direction are movably supported inward and outward by a support rod that can be elastically driven to expand and contract, and a receiving coil is installed on each contact piece. Receiving unit in 2. A receiving unit in a remote field eddy current type flaw detector according to claim 1, wherein the receiving coil is installed with the winding axis directed in the radial direction of the body. 3. The receiving unit according to claim 1, wherein the support rod is an operating rod of a pneumatic cylinder device, and an air communication space for distributing driving air to each pneumatic cylinder device is formed in a body. Unit in remote field eddy current type flaw detector 4. A receiving unit in a remote field eddy current type flaw detector according to claim 1, wherein the support bars of adjacent contact pieces are arranged in a staggered manner. 5. A receiving unit in a remote field eddy current type flaw detector according to claim 1, wherein the contact piece is made of a synthetic resin and both ends are curved inward. 6. A receiving unit in a remote field eddy current type flaw detector according to claim 5, wherein the synthetic resin is a polyacetal resin.