JPH0684955B2 - In-pipe inspection device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an in-pipe inspection device, and more particularly to an in-pipe inspection device having both an eddy current flaw detection means for detecting a defect existing in a cross section of a metal tube and an optical flaw detection means for visually observing an inner peripheral surface of the tube. Here, the “section of the pipe” has a meaning including the cross section at a certain position and the inner and outer peripheral surfaces in the vicinity thereof. In practice, the inner and outer peripheral surfaces are the main problem.

[Prior art]

In this type of in-pipe inspection device, conventionally, a pair of coils is arranged in the pipe to be inspected to form an eddy current over the entire circumference of the cross section of the pipe, and the eddy current is present in the cross section of the pipe by monitoring its impedance change. Eddy current flaw detection means for detecting defects, and guides the illumination light by a light guide and irradiates the inner peripheral surface of the tube from between the pair of coils via a rotating mirror,
A combination of optical flaw detection means for visually observing the inner peripheral surface of the tube to detect defects by monitoring the optical image of the inner peripheral surface of the tube obtained through a rotating mirror with an image guide has been proposed. . (Actual No. Sho 60-33313) In the above-mentioned in-pipe inspection device, the optical flaw detection means monitors the inner peripheral surface of the tube through the coils of the eddy current flaw detection means, so the spacing between the coils is large and the resolution is low. However, since the optical flaw detection means employs the rotating mirror, there is a problem that flaw detection work cannot be performed at high speed.
Even if the rotating mirror is replaced with a panoramic mirror to speed up the flaw detection work, the image is distorted and observed, such as circular defects on the inner peripheral surface of the tube appearing to be oval. When a defect is detected by generating an eddy current over the entire circumference of the cross section of the pipe, the position of the defect in the axial direction is known, but the position on the circumference is unknown, and even if there are multiple defects on the same circumference. It will be counted as one. Therefore, it has been proposed to use a sensor coil having an axis deviated from the central axis of the pipe to be inspected to detect the circumferential position of the defect. (Japanese Patent Laid-Open No. 60-157047) However, although the principle was disclosed, a device practically useful was not realized.

[Problems to be Solved by the Invention]

An object of the present invention is to maintain a high resolution of the eddy current flaw detection means, while simultaneously obtaining an optical image of a defect existing on the inner peripheral surface of the tube without distortion and over the entire circumference at the same time.
An object of the present invention is to provide an in-pipe inspection device capable of performing flaw detection work at high speed. Another object of the present invention is to be able to accurately know the circumferential position of the defect whose presence has been detected, following the axial position of the pipe, and to easily move in and out of the pipe. It is to provide an in-pipe inspection device that is practically easy to use.

[Means for Solving the Problems]

The in-pipe inspection apparatus of the present invention which achieves the above-mentioned object is essentially constituted by the following elements: A A cylindrical head member having an outer diameter close to the inner diameter of the pipe to be inspected, and coaxially wound on the cylindrical head member. A pair of circumferentially wound coils arranged at a slight distance and generating an eddy current over the entire circumference of the cross section of the tube to detect an existing defect, and at least the outer peripheral surface of the head member. A first eddy current flaw detection head provided with three running rollers which are in contact with the inner surface of the tube and rotate in the axial direction to assist the movement of the head member. B (i) A cylindrical guide head member having at least three outer peripheral surfaces. It is equipped with a traveling roller which is arranged in a circle and rotates in the axial direction in contact with the inner surface of the pipe to assist the movement of the guide head member, and the guide head member is connected to the annular portion centered on the rotary shaft of the rotary head and it. The rotating roller of the rotary head member is connected to the in-groove roller constrained by the guide groove via a spring and a base. When the rotary head is stationary, the in-groove roller is in the expanded portion and retracts the orbiting roller in the radial direction to be housed in the rotary head member, and when rotating, moves to the annular portion to advance the orbiting roller in the radial direction. A guide head configured to be pressed against the inner surface of the tube by means of a guide shaft, and (ii) a rotary head member supported by a common shaft with respect to the guide head and rotatably provided adjacent to the guide head, in contact with the inner surface of the tube. A rotating coil sensor, which is a locally wound coil, is installed so that it can move in and out in the radial direction of the pipe and generates an eddy current in a part of the circumference of the pipe cross section to detect existing defects. When the rotating head member rotates, the orbiting roller advances in the radial direction so as to come into contact with the inner surface of the pipe to orbit, and (iii) a motor case which is adjacent to the rotating head and does not rotate itself. A second eddy current flaw detection head consisting of a rotary drive unit with a built-in motor for rotating the rotary head inside, and a plurality of units that can guide the light from the C light source to irradiate the inner surface of the tube all around the circumference simultaneously. An optical flaw detection head having a plurality of image guides capable of simultaneously monitoring the inner surface of the tube with the light guide and at least the irradiation area of the light guide as the visual field through the light collecting member, and the optical flaw detection head It is located between the eddy current flaw detection head and the second eddy current flaw detection head.

[Action]

Needless to say, the first eddy current flaw detection head generates an eddy current over the entire circumference of the tube cross section by the circumferentially wound coil, and detects the presence of the defect by the change in impedance caused by the defect. At this time, the head is prevented from being shaken in the axial direction and rotated in the circumferential direction with the help of the traveling roller, and stable measurement can be performed. By placing the two coils at a small distance, high resolution can be obtained and the axial position of the defect can be precisely determined. The detected defect is then monitored by the optical flaw detection head, and the condition existing on the inner peripheral surface of the pipe can be visually confirmed. By using a plurality of light guides and a plurality of image sensors, the field of view is bright and the entire circumference can be viewed at one time, so that optical flaw detection can be performed at high speed. The second eddy current flaw detection head, of course, determines the circumferential position of the defect whose axial position has been detected. The guide head prevents axial deflection and rotation in the circumferential direction of the second eddy current flaw detection head and moves it, and also enables stable measurement. By placing two locally wound coils close together, detection with high resolution can be performed here as well. The rotating head rotates only when it reaches the axial position where the existence of defects is recognized by the first eddy current flaw detection head when necessary, and does not rotate other than that. Can be shortened. The rotary head can be smoothly rotated by the revolving roller, and the locally wound coil can rotate close to the inner peripheral surface of the tube, so that the sensitivity can be kept high.

【Example】

In FIG. 1, 10 is a first eddy current flaw detection head,
A cylindrical head member 11 having an outer diameter slightly smaller than the diameter of the inner peripheral surface 2 of the tube 1 and having bottoms at both ends, and a pair of circumferentially wound head members 11 arranged at appropriate distances from each other. Winding coil
It consists of 12,13. 14 and 15 are running rollers, 1 to each other
Each of the rollers is composed of three sets of rollers arranged on the peripheral surfaces of both ends of the coil support 11 at an angle of 20 degrees, and rotates while contacting with the inner peripheral surface 2 of the pipe 1, and Helps to move in the pipe. 20 is an optical flaw detection head, which is the first eddy current flaw detection head 10
It has a tubular body 22 which penetrates the central part of and is connected to the signal cable 21 at one end. The signal cable 21 is connected to a control device (not shown) arranged outside the pipe 1. Reference numeral 23 is a transparent member such as glass disposed on the peripheral surface of the other end of the tubular body 22, and the peripheral surface faces the inner peripheral surface 2 of the tube 1 and functions as a light transmitting portion. However, the transparent member 23 is not essential. Reference numeral 24 denotes a prism base concentrically arranged in the tubular body 22, and is 8 in the circumferential direction at a position facing the inner peripheral surface of the transparent member 23.
The prism 25 is attached at an equal angle. Prism 25
Is a right-angled prism and is fixed on a fixing member 26 arranged on the outer peripheral surface of the prism base 24. The prism 25 can be replaced with a plane mirror. Reference numeral 27 denotes eight sets of image guides each formed by bundling a plurality of optical fibers, each of which is arranged at an equal angle on the outer peripheral surface of the prism base 24, one end of which is connected to the prism 25 via the objective lens 28. Facing each other. Objective lens 28
And the prism 25 functions as a light collecting member of the image guide 27. As described above, since there are eight objective lenses 28 and prisms 25, which are arranged at equal angles in the circumferential direction, the fields of view of the objective lenses 28 overlap in the circumferential direction little by little, and It is possible to monitor the entire circumference of the annular region of the surface 2 at the same time. Each of 29 is arranged between the outer peripheral surface of the cylindrical reinforcing member 30 arranged around the image guide 27 and the inner peripheral surface of the cylindrical body 22, and is constituted by binding a plurality of optical fibers. 8
A pair of light guides, which are arranged at equal angles to each other in the circumferential direction, one end of each of which is a reflector 31 and a transparent member.
Light from the light source is emitted toward the inner peripheral surface 2 of the tube 1 via the transparent member 23 or directly via the transparent member 23. The areas on the inner peripheral surface 2 irradiated by the adjacent light guides 29 are made to overlap little by little, and the inner peripheral surface 2 is irradiated by an annular area having a predetermined width in the axial direction of the tube 1. To be done. The irradiation area substantially coincides with the visual field area of the objective lens 28. 40 is a second eddy current flaw detection head, which is a cylindrical guide head having an outer diameter slightly smaller than the diameter of the inner peripheral surface 2 of the pipe 1.
41, a cylindrical rotary head 42 having a similar outer diameter and rotatably connected to the guide head 41, and having a locally wound coil, and the other end of the cylindrical body 22 of the optical flaw detection head 20. And a drive unit 43 formed of a bottomed cylindrical motor case 43 and a motor 71 connected to the rotary head 42 so as to drive the rotation of the rotary head 42. Reference numeral 44 denotes a traveling roller, which is composed of three sets of rollers arranged on the peripheral surface of the guide head 41 at an angle of 120 degrees, and travels while contacting the inner peripheral surface 2 of the pipe 1.
Helps move the second eddy current flaw detection head. Reference numeral 45 denotes a shaft, the rotation axis of which coincides with the axis of the guide head 41, and is rotatably supported by the guide head 41 via a bearing 46. Reference numeral 47 is a guide groove provided on the end surface 41a of the guide head 41 facing the rotary head 42, and has an annular portion 47a and an expansion portion having a terminating portion (not shown) continuously extending in radius. It consists of 47b. 48 is the end wall of the rotary head 42, and the shaft 45
There is a hole 49 into which is inserted, and a through hole 50 extending in the radial direction is provided near the outer periphery. Reference numeral 51 denotes a revolving roller pivotally supported by a support frame 52, which is normally housed together with the support frame 52 in the rotary head 42, and when the rotary head 42 rotates, it is directed outward from a hole 53 on its peripheral surface. It projects and contacts the inner peripheral surface 2 of the tube 1. 54 is a guide space 56 formed between the end wall 48 and the intermediate wall 55.
Is a base that can move in the directions of arrows A and B, and is connected to the support frame 52 via a support rod 57. 58 is a support rod 57
Is a coil spring arranged around the circumference of the tube 1. The support frame 52 can be urged toward the inner peripheral surface 2 of the tube 1 to press the orbiting roller 51 against the inner peripheral surface 2 of the tube 1, and the orbiting roller pressed. The reference numeral 51 rotationally travels on the inner peripheral surface 2 of the pipe 1 in the circumferential direction. Reference numeral 59 is a groove roller, which is attached to the base 54 and is a through hole.
It is provided at the free end of a rod 60 passing through 50 and is constrained by a guide groove 47 of a guide head 41 to move. 61 is the other end wall of the rotary head 42, on which the encoder disk 62 is attached. 63 is the central hole 61a of the end wall 61
Further, the rotary shaft 42 is a fixed shaft that passes through the center hole 62a of the encoder disc 62 and is supported by the bearing 64 with respect to the center hole 61a, so that the rotary head 42 can rotate around it. A fixed ring 65 is arranged inside the rotary head 42 and is fixed to one end of the fixed shaft 63. Reference numeral 66 denotes a movable ring arranged in the rotary head 42, which is fixed to the end wall 61 or the peripheral wall 67, and the inner peripheral surface of which is a fixed ring.
It is in contact with the outer peripheral surface of 65. The fixed ring 65 and the movable ring 66 constitute one set of slip rings. 68 and 69 in FIG. 2 are coils arranged on the outer peripheral surface of the rotary head 42 in the direction of extension of the tube 1 and in close proximity to each other.
Connected to 65. A gear 70 is fixed to the encoder disc 62. A motor 71 is housed in the drive unit 43, and an output shaft 72 extends through the end wall 73. End wall 73
The other end of the fixed shaft 63 is inserted into and supported by the center hole of the. 74 is also a gear, and meshes with the gear 70 at the free end of the output shaft 72 of the motor 71. 75 is an optical sensor disposed on the outer peripheral portion of the end wall 73, detects the passage of a plurality of holes 62b opened at equal angles on the outer peripheral portion of the encoder disk 62, the rotational position of the rotary head 42, As a result, the rotational positions of the coils 68 and 69 are detected. Reference numeral 76 is a connecting member extending from the other end wall 77 of the motor case 43, and can be attached to and detached from the other end of the cylindrical body 22 of the optical flaw detection head 20 by rotating the screw member 78. To connect the coils 68, 69 to an external controller,
An electric wire (not shown) connected to the fixed ring 65 passes through a through hole in the fixed shaft 63 to supply electric power to the motor 71 and an electric wire for connecting the optical sensor 75 to the control device (both are shown in FIG. (Not shown) together with being guided into the tubular body 22 of the optical flaw detection head 20 through the through hole of the connecting member 76, then through the hollow tubular body 24 to reach the signal cable 21, and then the eddy current flaw detection head 10 Electric wire (not shown) for connecting the coils 12 and 13 to the controller, image guide
It is guided to the outside of the tube 1 together with 27 and the light guide 29. The operation of the in-pipe inspection device having the above-described configuration will be described. First, this device will be described with reference to the guide roller 51 of the eddy current flaw detection head 40.
In the state in which is stored in the rotary head 42, the guide head 41 is inserted into the tube 1 in the direction of arrow C in FIG. After being inserted into the pipe 1 to a predetermined position, the pipe inspection device moves in the direction of arrow D along the inner peripheral surface 2 of the pipe 1 by winding the signal cable 21 little by little. An eddy current is formed around the entire cross section of the tube 1 by causing an AC current to flow through the coils 12 and 13 of the eddy current flaw detection head 10 from a control device outside the tube 1 while moving. On the other hand, by applying light from the light source to the light guide 29 of the optical flaw detection head 20, the inner peripheral surface 2 of the tube 1 is irradiated over the entire circumference. At this time, the inner peripheral surface 2 of the tube 1 may be sequentially irradiated in the circumferential direction by sequentially applying light to the plurality of light guides 29. In this manner, the eddy current flaw detection head 10 monitors that the eddy current in the cross section of the tube 1 is disturbed by the defect due to the impedance change of the coils 12 and 13, and the optical flaw detection head 20 monitors the prism 25, the objective lens 28, and The image guide 27 allows visual inspection of defects on the inner peripheral surface of the tube 1. This visual monitoring may be performed simultaneously on the inner peripheral surface 2 of the tube 1 over the entire circumference thereof, or may be sequentially performed in the circumferential direction. Since the in-pipe inspection device moves in the direction of the arrow D, if there is a defect in the cross section of the pipe 1, its presence is first detected by the eddy current flaw detection head 10, and then for some time (between the coils 12, 13 and the transparent member 23). The shape and the like can be seen by the optical flaw detection head 20 after a time required for moving the distance). After some time (the time required to move the distance between the visual field area of the image guide 27 and the coils 68 and 69 of the second eddy current flaw detection head 40), the in-pipe inspection apparatus of the present invention is stopped. Then, the electric power is supplied from the control device to the motor 71 via the signal cable 21. When the motor 71 rotates, the encoder disc 62 and thus the rotary head 42 rotate via the gear 74 and the gear 70 of the output shaft 72 with respect to the guide head 41 and the motor cable 43. Along with that, the in-groove roller 59 moves in the guide groove 47 of the guide head 41 from the end portion of the expanded portion 47b toward the annular portion 47a. Then, the rod 60 fixed to the in-groove roller 59 moves in the through hole 50 toward the center, and the base 54 moves in the direction of arrow A. The orbiting roller 51 is in contact with the inner peripheral surface 2 of the tube 1 until the in-groove roller 59 returns from the annular portion 47a of the guide groove 47 to the expansion portion 47b. When the revolving roller 51 is in contact with the inner peripheral surface 2 of the tube 1, a desired frequency (generally, the first eddy current flaw detection head) is applied to the coils 68 and 69 via a slip ring having a fixed ring 65 and a movable ring 66. By passing an AC current of a frequency different from the frequency of the current applied to the coils 12 and 13 of the coil 10, for example, a higher frequency is preferable, an eddy current occurs in the local portion of the cross section of the tube 1 and the coils 68 and 69 Monitor whether the eddy currents are disturbed by defects due to impedance changes. The rotary head 42 continues to rotate with respect to the guide head 41 and the motor case 43, the presence of which is detected by the first eddy current flaw detection head 10, and in some cases, further optical flaw detection head.
The defects visually detected by 20 are again microscopically monitored by the eddy current. The rotation position of the rotary head 42 is determined by the optical sensor 75 and the hole 62b in the encoder disc 62.
The position of the defect on the circumference can be confirmed because it is detected by. The rotary head 42 makes at least one rotation with respect to the guide head 41 and the motor case 43. When the inspection work by the second eddy current inspection head 40 is completed,
Rotate the motor 71 in the reverse direction so that the rotary head 42 moves to the guide head 41.
By rotating in reverse with respect to the motor case 43, the in-groove roller 59 is moved from the annular portion 47a of the guide groove 47 to the expanded portion 47b.
The orbiting roller 51 moves toward the end of the rotary head 42.
Return to the guide space 56 of. After that, the eddy current flaw detector is moved again in the direction of arrow D, and the above-described operation is repeated.

【The invention's effect】

As is clear from the above description, the in-pipe inspection device of the present invention has the following effects. Since the coil spacing of the eddy current flaw detection means is narrow and its resolution is high, it is possible to accurately know the axial position of the defect existing in the cross section of the pipe. The defects detected by the eddy current flaw detection can be visually observed at the same time over the entire circumference by the optical flaw detection, and the defect visual recognition work can be performed at high speed and efficiently. Those that generate a signal similar to a defect, such as a scale attached to the inner surface of the tube, can be optically distinguished from a true defect. The rotating film is attached to a rotating head equipped with a revolving roller, and the rotating head can rotate close to the inner surface of the pipe with the rotating shaft securely held by the front and rear eddy current flaw detection heads, so that the defect is circular. It is possible to detect in detail in which position in the circumferential direction and the degree of the defect, and even when there are multiple defects on the same circumference,
We can know their numbers and positions accurately. The circumferential roller advances in the radial direction only when the rotary head rotates and contacts the inner surface of the tube, and is retracted when it does not rotate, so there is no hindrance to the entrance and exit of the inspection device and the running inside the tube. .

[Brief description of drawings]

The drawings each show an embodiment of the present invention,
FIG. 1 is a sectional view of a portion, and FIG. 2 is a sectional view of another portion. 1 ...... Tube 2 ...... Inner surface 10 ...... First eddy current flaw detection head 12, 13 ...... Circular winding coil 14, 15 ...... Traveling roller 20 ...... Optical flaw detection head 21 ...... Signal cable 23 ...... Transparent member 25 …… Prism 27 …… Image guide 28 …… Objective lens 29 …… Optical guide 31 …… Reflector 40 …… Second eddy current flaw detection head 41 …… Guide head 42 …… Rotating head 43 …… Motor case 44… … Running roller 47 …… Guide groove 51 …… Orbiting roller 62 …… Encoder disk 68,69 …… Locally wound coil 71 …… Motor 75 …… Optical sensor

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukihiko Koshiba 2197-46 Shimonagaya-cho, Konan-ku, Yokohama-shi, Kanagawa (56) References JP-A-60-157047 (JP, A) JP-A-57-39344 (JP, A) JP 60-177314 (JP, A) Actually opened 60-33313 (JP, U) Actually opened 50-94980 (JP, U) Actually opened 59-64565 (JP, U)

Claims (3)

[Claims] 1. A cylindrical head member consisting essentially of the following elements: A. A cylindrical head member having an outer diameter close to the inner diameter of the tube to be inspected, coaxially wound thereon and arranged a short distance away. And a pair of circumferentially wound coils which generate an eddy current over the entire circumference of the pipe cross section and detect an existing defect, and at least three of them are arranged on the outer peripheral surface of the head member and contact the inner surface of the pipe. A first eddy current flaw detection head equipped with a traveling roller which rotates in the axial direction and assists the movement of the head member, B (i) A cylindrical guide head member, at least three of which are arranged on the outer peripheral surface thereof and contact the inner surface of the pipe. The guide head member is provided with a traveling roller that rotates in a direction to assist the movement of the guide head member, and the guide head member is connected to the annular portion having the center on the rotation axis of the rotary head and the radius gradually increases to reach the end point. Expansion The rotating roller of the rotary head member is connected to the in-groove roller constrained by the guide groove via a spring and a base, and the groove is provided when the rotary head is stationary. A structure in which the inner roller is in the expanded portion and retracts the orbiting roller in the radial direction to be housed in the rotary head member, and when rotating, moves to the annular portion and advances the orbiting roller in the radial direction to press the inner surface of the pipe. (Ii) A rotating head member, which is supported by a common shaft for the guide head and is rotatably provided adjacent to the guide head, has a rotating roller that is in contact with the inner surface of the pipe and travels in the circumferential direction. A rotating coil sensor, which is a locally wound coil that detects deficiencies that exist by generating eddy currents in a portion of the circumference of the pipe cross section, is installed so that it can rotate in and out when the rotating head member rotates. A rotary head in which the roller advances in the radial direction and makes contact with the inner surface of the tube to circulate, and (iii) The rotary head is rotationally driven inside the motor case that is adjacent to the rotary head and does not rotate itself. A second eddy current flaw detection head including a rotary drive unit having a built-in motor, a light guide capable of guiding light from the C light source to irradiate the inner surface of the tube simultaneously over the entire circumference, and at least a light collecting member. A plurality of image guides that can simultaneously monitor the inner surface of the tube over the entire circumference with the irradiation area of the light guide as the field of view are arranged at equal angles on the circumference of eight sets. First, an optical flaw detection head and an optical flaw detection head that consist of a set of an objective lens having an optical axis in the direction and a prism that directs the field of view of the objective lens toward the inner peripheral surface of the tube Eddy current testing head and the second pipe inspection device comprising is positioned between the eddy current head. 2. In the second eddy current flaw detection head, the rotary head and the drive unit are rotatably coupled by a slip ring composed of an outer movable ring fixed to the rotary ring and an inner stationary ring extending from the drive unit. The in-pipe inspection device according to claim 1, wherein the gear is provided on the output shaft of the motor and the gear is fixed to the outer movable ring so that the gear is driven to rotate. 3. In a second eddy current flaw detection head, an encoder disk having holes formed at equal angles on a circumference centered on the rotation axis of the rotary head is attached to a position facing the drive unit side. The pipe inspection apparatus according to claim 1, further comprising an optical sensor for detecting passage of the hole.