JP2020144083A - Eddy current flaw detection probe and piping facility - Google Patents

Abstract

To improve detection precision of defects on an inner surface of a rifle tube.SOLUTION: An eddy current flaw detection probe 10 includes: a cable 11; a slip ring 12 provided in the tip of the cable 11; and a probe body 20 provided rotatably around an axis O relative to the cable 11 via the slip ring 12. The probe body 20 includes: a head 21 having a cylindrical outer peripheral surface 23 extending with the axis O as a center, and a spiral groove 24 that is recessed from the cylindrical outer peripheral surface 23 and is twisted in a circumferential direction of the axis O as it goes toward the axis O; and a coil 30 wound around the head 21 so as to surround the axis O according to shapes of the cylindrical outer peripheral surface 23 and the spiral groove 24.SELECTED DRAWING: Figure 1

Description

The present invention relates to eddy current flaw detection probes and piping equipment.

An eddy current flaw detection method is known as a non-destructive inspection method for defects such as scratches and wall thinning in pipes and the like. In this method, a coil through which an alternating current is passed is brought close to the inner peripheral surface of the pipe, and a change in eddy current generated in the pipe due to an electromagnetic induction phenomenon is detected.

For example, Patent Document 1 discloses an eddy current flaw detection method and an eddy current flaw detection probe for a tube having ribs on the inner surface. A plurality of ribs of the pipe are formed so as to protrude from the inner peripheral surface of the pipe and extend in the extending direction of the pipe and at intervals in the circumferential direction of the pipe. In this eddy current flaw detection method, a tube defect is detected by moving an eddy current probe having a coil arranged between the ribs in the extending direction of the ribs.

Japanese Unexamined Patent Publication No. 2008-1578898

Here, for example, a rifle pipe is applied to the heat transfer pipe of the exhaust gas cooler of the integrated coal gasification combined cycle for the purpose of improving the heat transfer efficiency. A spiral rib is formed on the inner surface of this rifle tube for the purpose of generating a swirling flow. Even with such a rifle tube, it is required to be able to detect defects such as thinning of the inner surface with high accuracy.
What is the shape of the ribs on such a rifle tube? It is different from the shape of the rib of the tube which is the target of the eddy current flaw detection probe of Patent Document 1. Therefore, it is not possible to accurately detect defects in the rifle tube using the eddy current flaw detection probe.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an eddy current flaw detection probe and piping equipment capable of improving the detection accuracy of defects such as thinning of the inner surface of the rifle pipe. To do.

The present invention employs the following means in order to solve the above problems.
That is, the eddy current flaw detection probe according to one aspect of the present invention is provided rotatably about the cable with respect to the cable via the cable, the slip ring provided at the tip of the cable, and the slip ring. The probe main body includes a cylindrical outer peripheral surface extending about the axis, and a spiral groove that is recessed from the cylindrical outer peripheral surface and twists in the circumferential direction of the axis toward the axis. A head having the head, and a coil wound around the head so as to surround the axis according to the shape of the outer peripheral surface of the cylinder and the spiral groove.
Have.

Further, the piping equipment according to one aspect of the present invention includes the above eddy current flaw detection probe, the inner peripheral surface of the cylinder, and a spiral that protrudes from the inner peripheral surface of the cylinder and is twisted in the circumferential direction toward the axial direction. A rifle tube having ribs, the spiral rib having a shape corresponding to the spiral groove.

The eddy current flaw detection probe having the above configuration is inserted inside a rifle tube having a spiral rib corresponding to the spiral groove of the eddy current flaw detection probe. As a result, when the spiral rib of the rifle tube enters the spiral groove of the head, the head advances while rotating according to the shape of the spiral rib and the spiral groove as the cable is inserted.
Here, the inner surface shape of the rifle tube is a uniform shape in which only the posture changes toward the extending direction of the rifle tube. That is, if the rifle tube is advanced in the extending direction, a similar inner surface shape will appear while rotating. In this aspect, since the outer peripheral surface of the cylinder and the spiral groove are formed in the head, the outer surface shape of the head is a shape corresponding to the inner surface shape of the rifle tube. Therefore, as the head advances while rotating in the rifle tube, the correspondence between the outer surface of the head and the inner surface of the rifle tube is maintained. As a result, the size of the gap between the outer surface of the head and the inner surface of the rifle tube can be made small and constant.

In the above eddy current flaw detection probe, the probe main body further has a shaft portion integrally provided with the head and extends in the axial direction from the head, and has a cylindrical shape provided on the outer peripheral surface of the shaft portion. , It is preferable to further provide a stabilizer having elasticity in the radial direction.

By elastically contacting the outer surface of the stabilizer with the inner surface of the rifle tube, the shaft portion and the head integrated with the shaft portion can be aligned with the center of the rifle tube. As a result, the posture of the head can be properly maintained.

The eddy current flaw detection probe may further include a bearing provided between the shaft portion and the stabilizer so that the stabilizer can rotate about the axis with respect to the shaft portion.

With the above configuration, the stabilizer can freely rotate relative to the shaft portion according to the shape of the spiral rib of the rifle tube. As a result, the alignment of the shaft portion and the head by the stabilizer can be further improved.

According to the eddy current flaw detection probe and the piping equipment of the present invention, it is possible to improve the detection accuracy of defects such as wall thinning on the inner surface of the rifle pipe.

It is the vertical sectional view of the rifle pipe and the side view of the eddy current flaw detection probe in the piping equipment which concerns on embodiment of this invention. It is a vertical sectional view of the rifle pipe in the piping equipment which concerns on embodiment of this invention. It is a vertical cross-sectional view of the eddy current flaw detection probe in the piping equipment which concerns on embodiment of this invention. FIG. 1 is a sectional view taken along line IV-IV of FIG.

Hereinafter, the piping equipment 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the piping equipment 100 includes an eddy current flaw detecting target rifle pipe 1 and an eddy current flaw detecting probe 10 inserted into the eddy current flaw detecting pipe 1.

<Rifle tube>
As shown in FIG. 2, the rifle tube 1 has a tubular shape with a hollow inside. The rifle pipe 1 is used as a heat transfer pipe of an exhaust gas cooler for cooling exhaust gas in, for example, an integrated gasification combined cycle facility.

The inner surface 2 of the rifle tube 1 is formed by a cylindrical inner peripheral surface 3 and a spiral rib 4.
As shown in FIGS. 2 and 4, the inner peripheral surface of the cylinder 3 has a cylindrical surface shape centered on the axis O extending in the extending direction of the rifle tube 1. The inner peripheral surface 3 of the cylinder has a uniform inner diameter in the axis O direction.

The spiral rib 4 protrudes inward in the radial direction from the inner peripheral surface 3 of the cylinder. The spiral rib 4 has a spiral shape extending so as to be twisted to one side in the circumferential direction toward one side in the O-direction of the axis. The cross-sectional shape of the spiral rib 4 including the axis O has a convex shape in which the widthwise dimension of the spiral rib 4 decreases toward the inside in the radial direction of the rifle tube 1.

As shown in FIG. 4, the arbitrary cross-sectional shape of the inner surface 2 of the rifle tube 1 in the axis O direction is a shape in which the inner peripheral surface of the cylinder 3 and the spiral rib 4 are present. The inner peripheral surface 3 of the cylinder is a part of the circumferential direction and has an arc shape along a virtual circle centered on the axis O. The spiral rib 4 is the remaining region of the inner surface 2 of the rifle tube 1 in the circumferential direction, and has a curved shape located inside the radial direction of the virtual circle centered on the axis O.

The cross-sectional shape of the inner surface 2 of the rifle tube 1 has a uniform shape in which only the posture changes as the rifle tube 1 extends in the extending direction. That is, if the rifle tube 1 is advanced in the extending direction, the same cross-sectional shape will appear while rotating. A spiral groove 6 corresponding to the spiral rib 4 is formed on the outer peripheral surface 5 of the rifle tube 1.

<Eddy current flaw detection probe>
Next, the eddy current flaw detection probe 10 will be described.
As shown in FIGS. 1 and 3, the eddy current flaw detection probe 10 includes a cable 11, a slip ring 12, a probe body 20, a bearing 41, and a stabilizer 50.

<Cable>
The cable 11 is a flexible and elongated member. Inside the cable 11, wiring for power supply and wiring for signal are housed so as to extend in the extending direction of the cable 11.

<Slip ring>
The slip ring 12 is provided at the tip of the cable 11. The slip ring 12 has, for example, a fixed body fixed to the tip of the cable 11 and a rotating body rotatably provided around the axis O with respect to the stator on the side of the fixed body opposite to the cable 11. .. The slip ring 12 is configured such that power and signals are transmitted through the brush between the fixed body and the rotor.

<Probe body>
The probe main body 20 is integrally fixed to a rotating body located on the opposite side of the slip ring 12 from the cable 11. The probe body 20 is freely rotatable about the axis O with respect to the cable 11 via the slip ring 12.
The probe main body 20 has a head 21, a coil 30, a first shaft portion 31 as a shaft portion, and a second shaft portion 32.

≪Head≫
The head 21 has a substantially columnar shape extending about the axis O. The outer surface 22 of the head 21 facing outward in the radial direction has a cylindrical outer peripheral surface 23 and a spiral groove 24.
The outer peripheral surface of the cylinder 23 has a cylindrical surface shape centered on the axis O. The outer peripheral surface 23 of the cylinder has a uniform outer diameter in the axis O direction.

The spiral groove 24 is a groove formed so as to be recessed inward in the radial direction from the outer peripheral surface 23 of the cylinder. The spiral groove 24 has a spiral shape extending so as to be twisted to one side in the circumferential direction toward one side in the O direction of the axis. The cross-sectional shape of the spiral groove 24 including the axis O has a concave shape in which the dimension in the width direction decreases toward the inner side in the radial direction of the rifle tube 1.

Here, the outer diameter of the cylindrical outer peripheral surface 23 of the head 21 has a shape corresponding to the cylindrical inner peripheral surface 3 of the rifle tube 1. That is, the outer diameter of the cylindrical outer peripheral surface 23 of the head 21 is slightly smaller than the cylindrical inner peripheral surface 3 of the rifle tube 1. As a result, the portion where the cylindrical outer peripheral surface 23 in the axis O direction of the head 21 is formed can be inserted into the portion where the cylindrical inner peripheral surface 3 in the axis O direction of the rifle tube 1 is formed.

The spiral groove 24 of the head 21 has a shape corresponding to the spiral rib 4 of the rifle tube 1. That is, the pitch of the spiral groove 24 is the same as the pitch of the spiral rib 4, and the concave contour of the spiral groove 24 of the head 21 has a shape slightly larger than the convex contour of the spiral rib 4 of the rifle tube 1. I'm doing it. As a result, the spiral rib 4 can be fitted into the spiral groove 24 along the axis O direction.

As shown in FIG. 4, the cross-sectional shape orthogonal to the axis O on the outer surface 22 of the head 21 is a shape corresponding to the cross-sectional shape orthogonal to the axis O on the inner surface 2 of the rifle tube 1. When the head 21 of the rifle tube 1 is coaxially inserted into the rifle tube 1, the cylindrical outer peripheral surface 23 of the head 21 and the cylindrical inner peripheral surface 3 of the rifle tube 1 are located at the same circumferential position. A uniform and small amount of radial gap is formed between the cylindrical outer peripheral surface 23 of the head 21 and the cylindrical inner peripheral surface 3 of the rifle tube 1. The spiral groove 24 of the head 21 and the spiral rib 4 of the rifle tube 1 are located at the same circumferential position. A uniform and small amount of radial gap is formed between the spiral groove 24 of the head 21 and the spiral rib 4 of the rifle tube 1.

≪Coil≫
As shown in FIGS. 1, 3 and 4, the coil 30 has a ring shape wound around the outer peripheral surface of the head 21 so as to surround the axis O. In this embodiment, a pair of coils 30 are provided so as to be separated from each other in the axis O direction. The pair of coils 30 have the same configuration as each other. Each of these coils 30 has a function of both exciting and receiving. By outputting the difference between the detection signals of the pair of coils 30 as an output, it is possible to eliminate an error due to rattling of the posture of the probe main body 20 or the like.

As shown in FIG. 3, the coil 30 is fitted in a coil groove 25 formed so as to be recessed in the circumferential direction on the outer surface 22 of the head 21. The shape of the outer peripheral surface of the coil 30 is the same as the shape of the outer surface 22 of the head 21 at the position where the coil groove 25 is formed. Therefore, as shown in FIG. 4, the cross-sectional shape orthogonal to the axis O of the coil 30 is a shape corresponding to the inner surface 2 of the rifle tube 1. Therefore, when the head 21 is coaxially inserted into the rifle tube 1, the radial gap between the coil 30 and the inner surface 2 of the rifle tube 1 extends in the circumferential direction, similar to the relationship between the head 21 and the rifle tube 1. Uniform and small amount.

≪First axis part≫
The first shaft portion 31 has a columnar shape extending about the axis O. The outer diameter of the first shaft portion 31 is smaller than the outer diameter of the head 21. The first shaft portion 31 is provided coaxially and integrally with the head 21 on the rear end side of the head 21 on the cable 11 side. The rear end of the first shaft portion 31 forms the rear end of the probe main body 20, and is fixed to the slip ring 12.

≪Second axis part≫
The second shaft portion 32 has a columnar shape extending about the axis O. The outer diameter of the second shaft portion 32 is smaller than the outer diameter of the head 21. The second shaft portion 32 is coaxially and integrally fixed to the tip end side of the head 21. The tip of the first shaft portion 31 forms the tip of the probe main body 20.

≪Bearing≫
A pair of bearings 41 are provided so as to correspond to the first shaft portion 31 and the second shaft portion 32. The bearing 41 has a cylindrical shape that is fitted onto the outer surface 22 of each of the first shaft portion 31 and the second shaft portion 32. The bearing 41 is configured as a so-called rolling bearing 41 that rotates in the circumferential direction.

≪Stabilizer≫
The stabilizer 50 shown in FIGS. 1 and 3 has a role of aligning the probe main body 20. That is, the stabilizer 50 maintains the posture of the probe main body 20 coaxially with the rifle tube 1. The dimension of the stabilizer 50 in the axis O direction is larger than the pitch of the spiral groove 24 in the rifle tube 1.
A pair of stabilizers 50 are provided so as to correspond to the first shaft portion 31 and the second shaft portion 32. The stabilizer 50 is formed of a flexible material such as resin. The stabilizer 50 has a fixing portion 51 and an elastic portion 52.

≪Fixed part≫
The fixed portion 51 has a cylindrical shape that is coaxially fitted to the bearing 41 on the outer peripheral side of the first shaft portion 31 and the bearing 41 on the outer peripheral side of the second shaft portion 32, respectively. Since the fixing portion 51 is fixed to the bearing 41, the stabilizer 50 can freely rotate relative to the first shaft portion 31 and the second shaft portion 32 around the axis O.

≪Elastic part≫
The elastic portion 52 has a cylindrical shape arranged coaxially with the fixed portion 51 on the outer peripheral side of the fixed portion 51. The ends of the elastic portion 52 on both sides in the axis O direction extend inward in the radial direction and are connected to the ends on both sides of the fixed portion 51 in the axis O direction. The intermediate portion of the elastic portion 52 in the axial direction O direction has a shape that bulges outward in the radial direction. A space is formed between the elastic portion 52 and the fixed portion 51 along the axis O direction. The outer diameter of the elastic portion 52 is set to be larger than the inner diameter of the spiral groove 24 of the rifle tube 1.

As shown in FIG. 1, the elastic portion 52 is formed with a slit 54 that penetrates the elastic portion 52 in the radial direction and extends in the longitudinal direction in the axis O direction. A plurality of elastic portions 52 are formed in the entire circumferential direction of the elastic portion 52 at intervals in the circumferential direction. As a result, a leaf spring 53 that extends in the longitudinal direction along the axis O and exhibits elasticity in the radial direction is formed in the portion of the elastic portion 52 that is sandwiched between the slits 54 that are adjacent to each other in the circumferential direction.

<Action effect>
When inspecting the inner surface 2 of the rifle pipe 1 with the piping equipment 100 having the above configuration, the eddy current flaw detection probe 10 is inserted into the rifle pipe 1. At this time, when the spiral rib 4 of the rifle tube 1 enters the spiral groove 24 of the head 21, the probe body 20 is inserted into the rifle tube 1 from the rear end side via the cable 11. And, it advances while rotating according to the shape of the spiral groove 24.

Here, as described above, since the cylindrical outer peripheral surface 23 and the spiral groove 24 are formed on the head 21, the outer surface 22 shape of the head 21 is a shape corresponding to the inner surface shape of the rifle tube 1. Therefore, when the head 21 advances in the rifle tube 1, the head 21 rotates following the shape of the inner surface of the rifle tube 1, so that the outer surface 22 of the head 21 and the inner surface 2 of the rifle tube 1 correspond to each other. Is maintained. As a result, the size of the gap between the outer surface 22 of the head 21 and the inner surface 2 of the rifle tube 1 when the head 21 is advanced can be made small and constant.

Therefore, it is possible to improve the detectability of defects such as thinning of the inner surface 2 of the rifle tube 1 by the pair of coils 30. Further, by adjusting the insertion speed of the probe main body 20, that is, the feed amount in the axis O direction, smooth inspection can be performed.

Further, when the probe main body 20 is inserted into the rifle tube 1, the leaf spring 53 on the outer surface 22 of the stabilizer 50 elastically contacts the spiral rib 4 on the inner surface 2 of the rifle tube 1. In the present embodiment, the outer surface 22 of the stabilizer 50 abuts on the spiral rib 4 at least three points in the cross section including the axis O. As a result, the shaft portion and the head 21 integrated with the shaft portion can be aligned with the center of the rifle tube 1, and the coaxiality between the rifle tube 1 and the probe main body 20 can be ensured.
As a result, the posture of the head 21 can be maintained appropriately, so that it is possible to prevent the head 21 from being inadvertently tilted and affecting the defect detectability. Therefore, the gap between the outer surface 22 of the head 21 and the inner surface 2 of the rifle tube 1 can be more reliably made small and constant.

Further, in the present embodiment, the stabilizer 50 can rotate relative to the probe main body 20 via the bearing 41. Therefore, the stabilizer 50 can freely rotate relative to the probe body 20 according to the shape of the spiral rib 4 of the rifle tube 1. Thereby, the alignment property of the probe main body 20 by the stabilizer 50 can be further improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately modified without departing from the technical idea of the invention.

1 Rifle tube 2 Inner surface 3 Cylindrical inner peripheral surface 4 Spiral rib 5 Outer surface 6 Concave groove 10 Vortex current flaw detection probe 11 Cable 12 Slip ring 20 Probe body 21 Head 22 Outer surface 23 Cylindrical outer surface 24 Spiral groove 25 Coil groove 30 Coil 31 1st shaft 32 2nd shaft 41 Bearing 50 Stabilizer 51 Fixed part 52 Elastic part 53 Leaf spring 54 Slip 100 Piping equipment O Axis line

Claims (4)

With the cable
A slip ring provided at the end of the cable and
A probe body rotatably provided around the axis of the cable via the slip ring,
With
The probe body
A head having a cylindrical outer peripheral surface extending about the axis, and a spiral groove that is recessed from the cylindrical outer peripheral surface and twists in the circumferential direction of the axis as it goes toward the axis.
A coil wound around the head so as to surround the axis according to the shape of the outer peripheral surface of the cylinder and the spiral groove.
Eddy current flaw detection probe with. The probe body
Further having a shaft portion integrally provided with the head and extending from the head in the axial direction.
The eddy current flaw detection probe according to claim 1, further comprising a stabilizer having a cylindrical shape and having elasticity in the radial direction provided on the outer peripheral surface of the shaft portion. The eddy current flaw detection probe according to claim 2, further comprising a bearing provided between the shaft portion and the stabilizer so that the stabilizer can rotate about the axis with respect to the shaft portion. The eddy current flaw detection probe according to any one of claims 1 to 3,
A rifle tube having an inner peripheral surface of a cylinder and a spiral rib protruding from the inner peripheral surface of the cylinder and twisting in the circumferential direction toward the axial direction.
With
The spiral rib is a piping facility having a shape corresponding to the spiral groove.

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