JPS6385441A - In-tube inspection probe - Google Patents

Abstract

PURPOSE:To detect the position and extent of a defect with high accuracy by providing coils of two eddy current flaw detecting means for detecting defects present in mutually adjacent sections of a tube and detects present in a circumferential direction along the inner circumferential surface of the tube. CONSTITUTION:A couple of coils 12 and 13 of a 1st eddy current flaw detecting means 10 are arranged in the space containing the mutually adjacent sections of the tube 1. Then an eddy current is generated over the entire circumferences of the sections and defects present in the sections are detected from variation in impedance. Further, a couple of coils 68 and 69 of a 2nd eddy current flaw detecting means 40 are arranged at an interval while directed in the prolongation direction of the tube 1 and movable in the circumferential directions along the internal circumferential surface of the tube 1. Then, an eddy current is formed locally in the sections of the tube 1 and the defect present at the local part is detected from variation in impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the invention "Field of industrial application" The present invention relates to an in-pipe inspection probe, and in particular to a first eddy current flaw detection means for detecting the presence or absence of defects in the cross section of a pipe. The present invention relates to an in-pipe inspection probe comprising: and a second eddy current flaw detection means for detecting where in the circumferential direction a defect exists in a cross section of the pipe.

[Prior Art] Conventionally, this type of pipe inspection probe has a method in which a pair of coils are arranged in a space including mutually adjacent cross sections of the pipe, and an eddy current is formed around the entire circumference of the pipe cross section, and its impedance changes. It has been proposed to include an eddy current flaw detection means for detecting the presence or absence of defects in the cross section of the tube by monitoring.

[Problems to be solved] However, with conventional pipe inspection probes, (i) although it is possible to detect the presence of a defect in the cross section of the pipe, it is difficult to determine where in the circumferential direction the defect exists and the extent of the defect; There were drawbacks that could not be detected in detail, and therefore the tube had to be extracted and examined directly in order to provide detailed information about the results.

Therefore, the present invention provides a first eddy current flaw detection means for detecting whether or not a defect exists in the cross section of a pipe, and a first eddy current flaw detection means for detecting at which position in the circumferential direction the defect exists in the cross section of the pipe. The present invention aims to provide an in-pipe inspection probe that is equipped with the eddy current flaw detection means (2), which can detect defects in the cross section of the pipe in detail without conducting sampling inspections, and can perform flaw detection at high speed and with high precision. be.

(2) Structure of the Invention [Means for Solving Problems] To achieve this, the present invention provides: ``(a) eddy currents are formed in spaces that include mutually adjacent cross sections of the tube, and that form eddy currents over the entire circumference of the cross sections. and (b) a first eddy current flaw detection means including a pair of coils for detecting defects present in the cross section by a change in impedance; The tube is movable in the circumferential direction along the inner circumferential surface of the tube, and includes another pair of coils that form an eddy current locally in the cross section of the tube and detect defects existing in the localized area by changing impedance. The problems of the prior art are solved by the "intra-pipe inspection probe" characterized in that it is equipped with a second eddy current flaw detection means.

[Function] The pipe inspection probe of the present invention detects defects existing in the cross section of the pipe while maintaining high resolution using the coils of the first eddy current flaw detection means arranged in the spaces including mutually adjacent cross sections of the pipe. In addition, the coils of the second eddy current flaw detection means, which are arranged spaced apart from each other in the direction of extension of the pipe and are movable in the circumferential direction along the inner circumferential surface of the pipe, detect local parts of the cross section of the pipe. Detects defects existing in the image while maintaining high resolution.

[Example] Next, the intraductal inspection probe of the present invention will be specifically described with reference to Examples.

FIG. 1 is a partial sectional view showing one embodiment of the present invention.

FIG. 2 is another partial sectional view.

First, the configuration of the pipe inspection probe of the present invention will be explained.

The first eddy current flaw detection means of the pipe inspection probe of the present invention includes a cylindrical casing 11 having an outer diameter slightly smaller than the diameter of the inner circumferential surface 2 of the pipe 1, and a central periphery of the casing 11. It includes a pair of coils 12, 13 which are wound circumferentially around the surface and are appropriately spaced from each other. A coil cover may be placed on the circumferential surface of the coil 12, 13 if desired. 1
Reference numeral 4 denotes first guide rollers, which are composed of three sets of rollers arranged against the circumferential surface of one end of the casing 11 at a distance of 120 degrees from each other. tube l
It is said that it can be rotated in the direction of extension. Reference numeral 15 denotes second guide rollers, which are composed of three sets of rollers arranged 120 degrees apart from each other on the circumferential surface of the other end of the body 11, and are in contact with the inner circumferential surface 2 of the tube 1. while rotating in the direction of extension of the tube l. Reference numeral 16 denotes a connecting cylinder, which penetrates the center of the housing 11 from one end to the other. (not shown).

赳 is the second eddy current flaw detection means of the pipe inspection probe of the present invention, which includes a cylindrical first housing small portion 41 having an outer diameter slightly smaller than the diameter of the inner circumferential surface 2 of the pipe l; a cylindrical second casing small part 42 having an outer diameter slightly smaller than the diameter of the inner peripheral surface 2 and rotatably connected to the first casing small part 41;
A cylindrical third small casing that is detachably connected to the other end of the connecting cylinder 16 of the eddy current flaw detection method and connected to the second small casing 42 so as to allow its rotation. 43.

Guide rollers 44 are composed of three sets of rollers arranged 120 degrees apart from each other on the circumferential surface of the first housing small part 41, and are in contact with the inner circumferential surface 2 of the tube 1. tube l
It is said that it can be rotated in the direction of extension. 45 is the rotation axis,
The central axis is made to coincide with the central axis of the first small housing part 41, and is rotatably supported by the first small housing part 41 via a bear link 46. Reference numeral 47 denotes a guide groove bored in the end surface 41a of the first small housing part 41 facing the second small housing part 4Z, which is continuous with the annular part 47a, gradually expands in radius, and has a terminal end. (not shown).

Reference numeral 48 denotes an end wall of the second housing small portion 42, in which a hole 49 into which the rotating shaft 45 is inserted and loosely fitted (may be fixed) is bored in the center, and a hole 49 in the outer peripheral portion is formed. A through hole 50 extending in the radial direction is bored. 51 is a support frame 52
It is a guide roller pivotally supported by the support frame 52 and is housed in the second housing small part 42 .
When the second housing small part 42 is rotated, it projects outward from the hole 53 in the circumferential surface of the second housing small part 42 and comes into contact with the inner circumferential surface 2 of the tube l. 5
4 is a base movable in the directions of arrows A and B in the guide space 56 formed between the end wall 48 and the intermediate wall 55;
It is connected to the support frame 52 via 7. 58 is rod 5
The support frame 52 is attached to the coil arranged around the tube l.
The guide roller 51 is pressed in two directions on the inner peripheral surface of the pipe 1.
As a result, the guide roller 51 rotates the inner circumferential surface 2 of the tube 1 in the circumferential direction. 5
A guide roller 9 is fixed to the base 54 and has a through hole 50.
The rod 60 is disposed at the free end of the rod 60 and is loosely fitted into the guide groove 47 of the first small housing section 41 . Reference numeral 61 denotes the other end wall of the second housing small portion 42, and an encoder disk 62 is fixed thereto. 63 is the center hole 6 of the end wall 61
1a and the fixed shaft inserted through the center hole 62a of the encoder disc 62 is supported by the center hole 61a via a bearing 64, and the second housing small part 42 can rotate around it. has been done. Reference numeral 65 denotes a fixing ring disposed within the second housing small portion 42 and fixed to one end of the fixing shaft 63. 66 is the second housing small part 42
The movable ring disposed inside is fixed to the end wall 61 or peripheral wall 67 of the second housing small portion 42, and its inner peripheral surface is in contact with the outer peripheral surface of the fixed link 65. .

The fixed ring 65 and the movable link 66 constitute a set of slip rings. 68 and 69 are arranged close to each other on the outer circumferential surface of the second housing small part 42, and are arranged in the extending direction of the tube 1, and are connected to the fixed link 65 via the movable link 66. It is connected to the. A coil cover may be placed on the circumferential surface of the coils 68, 69 if desired. A gear 70 is fixed to the encoder disk 62.

Reference numeral 71 denotes a motor, which is housed in the third housing small portion 43 and passes through the output shaft 72 or the end wall 73 thereof.

The other end of the fixed shaft 63 is inserted into the center hole of the end wall 73 and supported. A gear 74 is attached to the free end of the output shaft 72 of the dryer 71 and is meshed with the gear 70. Reference numeral 75 denotes an optical sensor disposed on the outer periphery of the end wall 73, which detects passage through a plurality of holes 62b formed at equal angles on the outer periphery of the encoder disc 62, and detects the passage of the second housing small. The rotational position of the section 42 and, in turn, the rotational position of the coils 68 and 69 are detected.

Reference numeral 76 denotes a connecting member protruding from the other end wall 77 of the third decoration small portion 43, which can be attached to and detached from the other end of the connecting cylinder 16 by rotating the screw member 78. connected.

Electric wires (not shown) connected to the fixed link 65 for communicating the coils 68, 69 to a control device located outside the tube 1 pass through a through hole (not shown) in the fixed shaft 63 and then An electric wire (not shown) that supplies power to the dryer 71 from a control device outside the tube 1 and an electric wire (not shown) that connects the optical sensor 75 to the control device outside the tube 1 are connected to the connecting member 76. The signal cable 17 is guided through a through hole (not shown) into the connecting cylinder 16 of the eddy current deep damage means rule.
9 coils for eddy current testing means 12.1.3
is led to the outside of the tube 1 along with electrical wires (not shown) for communicating with a control device outside the tube 1.

Furthermore, the operation of the intraductal inspection probe of the present invention will be explained.

The in-pipe inspection probe of the present invention is inserted into the pipe l in the direction of arrow C with the eddy current flaw detection means at the top, with the guide roller 51 of the eddy current deep flaw means stored in the small housing part 42. . The in-pipe inspection probe of the present invention is inserted deep into the pipe 1 via the signal cable 17. After being inserted into the pipe 1 to a desired position, the pipe inspection probe of the present invention begins to be moved in the direction indicated by the arrow along the inner circumferential surface 2 of the pipe 1 by winding up the signal cable 17 little by little.

When the pipe inspection probe of the present invention starts to move in the direction of the arrow in the pipe 1, a current of a desired frequency is applied to the coil 12. As a result, eddy currents are formed all around the cross section of the tube l. Therefore, in the eddy current flaw detection method, the tube 1 is
It begins to be monitored whether the eddy currents in the cross section are disturbed by the defect. The pipe interior inspection probe of the present invention is moved in the direction of the arrow, and if there is a defect in the cross section of the pipe 1, its presence is first detected by the eddy current flaw detection means.

For some time (that is, if the eddy current flaw detection method is used, the coil 12.
13 and the coils 68, 69 of the eddy current deep wound means), the intraductal inspection probe of the present invention is stopped.

When the pipe inspection probe of the present invention is stopped, the pipe 1
Electric power is supplied to the motor 7I via the signal cable 17 from an external control device. When the motor 71 is started,
The encoder disk 62 and, in turn, the small housing portion 42 are connected to the small housing portion 4], 4 via the gear 74 and gear 70 of the output shaft 72.
3, the rotation is started. Along with this, the guide roller 59 begins to be guided within the guide groove 47 of the small housing section 41. In other words, the guide roller 59 begins to be guided from the end of the expanded portion 47b of the guide groove 47 toward the annular portion 47a. The rod 60 fixed to the guide roller 59 is moved inward within the through hole 50, and as a result, the base 54 begins to be moved in the direction of arrow A in the guide space. The guide roller 59 is connected to the guide groove 4
The guide roller 51 is in contact with the inner circumferential surface 2 of the tube 1 by the time it moves from the expanded portion 47b of No. 7 to the annular portion 47a.

By the time the guide roller 51 comes into contact with the inner circumferential surface 2 of the pipe 1, a desired frequency (generally eddy current flaw detection device) is applied to the coil fi8. A current of a frequency different from the frequency of the current applied to the coils 12 and 13 (for example, a high frequency) begins to flow, and eddy currents are formed locally in the cross section of the tube l, and the impedance of the coils 68 and 69 changes. It begins to be monitored whether the eddy currents are disturbed by defects or not.

The housing subsection 42 is subsequently rotated relative to the housing subsection 41, 43 and microscopic monitoring is again carried out via eddy currents for defects whose presence has been detected by the eddy current detection means. The rotational position of the small housing portion 42 is detected by the optical sensor 75 and the hole 62b of the encoder disc 62, and the position of the defect is confirmed. The small housing part 42 is
It is rotated at least once relative to the housing subsection 41,43.

When the flaw detection work using the eddy current flaw detection method is completed, the motor 7
1 is reversely rotated, the housing small part 42 is reversely rotated with respect to the housing small part 41, 43, and the guide roller 59 is rotated from the annular part 47a of the guide groove 47 toward the terminal end of the expanded part 47b. The guide roller 51 is moved and housed in the guide space 56 of the small housing section 42.

Thereafter, the eddy current flaw detection probe of the present invention starts moving in the direction of the arrow again, and the above-described operation is repeated.

(3) Effects of the invention As is clear from the above, the pipe inspection glove of the present invention has the following effects:
(a) A pair of coils each disposed in a space containing mutually adjacent cross sections of the tube, forming an eddy current around the entire circumference of the cross section, and detecting defects present in the cross section by a change in impedance; (b) a first eddy current flaw detection means arranged at a distance from each other in the direction of extension of the pipe and movable in the circumferential direction along the inner circumferential surface of the pipe; and a second eddy current flaw detection means comprising another pair of coils that form an eddy current locally and detect defects existing locally by changes in impedance. It has the effect of speeding up the flaw detection work by first detecting whether or not a defect exists in the cross section of the pipe, and (ii) detecting whether there is a defect in the cross section of the pipe or where in the circumferential direction it exists. In addition, the degree of the defect can be detected in detail, which has the effect of increasing the accuracy of flaw detection work, and (iii) it can supply currents of different frequencies to two pairs of coils, and in turn, it can supply currents of different frequencies to each pair of coils. On the other hand, it has the effect of improving the accuracy of defect detection without individually supplying two or more types of currents with different frequencies.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing one embodiment of the present invention, and FIG. 2 is a partial sectional view of the same area.

Claims (6)

[Claims] (1) (a) A pair of coils, each of which is disposed in a space containing mutually adjacent cross sections of the tube, forms an eddy current around the entire circumference of the cross section, and detects defects existing in the cross section by changes in impedance. (b) arranged spaced apart from each other in the direction of extension of the pipe and movable in the circumferential direction along the inner circumferential surface of the pipe; and a second eddy current flaw detection means comprising another pair of coils that form an eddy current locally in the cross section of the tube and detect defects existing in the locally based on a change in impedance. Characteristic pipe inspection probe. (2) In-pipe inspection according to claim (1), wherein the first eddy current flaw detection means includes a first guide roller that comes into contact with the inner circumferential surface of the pipe. probe. (3) Claims (1) to (2) characterized in that the second eddy current flaw detection means includes a second guide roller that comes into contact with the inner peripheral surface of the pipe. ) The in-pipe inspection probe described in any one of the above items. (4) The second eddy current flaw detection means rotates a small part of the casing on which another pair of coils are arranged on the circumferential surface and is rotatable along the inner peripheral surface of the tube, and the small part of the casing. another gear fixed to the small housing part and meshed with the gear of the output shaft of the motor; and a movable ring fixed to the small housing part and another pair of coils. Claims (1) to (3) include a slip ring for supplying current to the
) The in-pipe inspection probe described in any one of the above items. (5) The second eddy current flaw detection means includes a guide groove including an annular part having a center on the rotation axis of the small casing part and an expanded part continuous with the annular part and having a gradually expanded radius, and the guide groove. a third guide roller that is inserted into the housing and moves along the expanded portion and the annular portion as the small housing portion rotates; and a base that is connected to the third guide roller; Said third
When the third guide roller is inserted into the expanded portion, the third guide roller is housed in the small housing portion, and when the third guide roller is inserted into the annular portion, the third guide roller protrudes from the small housing portion, and the third guide roller is inserted into the annular portion. a fourth mounted on the base that abuts the inner circumferential surface;
An in-duct inspection probe according to claim (4), characterized in that it includes a guide roller. (6) The second eddy current flaw detection means is an encoder circle that is fixed to a small part of the casing and has holes drilled at equal angles on a circumference centered on the rotation axis of the small part of the casing. Claim (4) or Claim 1, characterized in that it includes a plate and an optical sensor that is disposed at a position facing the hole and detects passage through the hole. The in-duct inspection probe described in (5).