JP2012018071A - Inspection device for pipe internal surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device, allowing an internal surface flaw of a small diameter pipe to be steadily detected with a pressing means that presses an inserting probe at an appropriate pressure against the internal surface of the test object pipe through a non-fluid contact medium.SOLUTION: An inspection device 1 for pipe internal surface detects an internal surface flaw K of a test object pipe W using ultrasonic waves. The pipe W has an inner diameter allowing capillary phenomenon to occur in a hole. The device comprises an inserting probe 2 that is capable of being inserted into the hole of the pipe W and has a transmitting and receiving surface 2a for transmitting and receiving the ultrasonic waves to and from the internal surface of the pipe W, a non-fluid contact medium 3 that is disposed between the inserting probe 2 and the internal surface of the pipe W, and pressing means 4 that presses the inserting probe 2 against the internal surface of the pipe W, so that the ultrasonic waves can be transmitted through the non-fluid contact medium 3.

Description

  The present invention relates to a pipe inner surface inspection device for nondestructively detecting defects existing on the inner surface of a pipe material such as a seamless steel pipe to be inspected.

It is important that pipe materials such as seamless steel pipes with no seams have not only scratches and cracks on the inner surface, but also defects on the metal structure (hereinafter simply referred to as “defects”). Unlike the surface, the inner surface tends to be difficult to inspect.
The conventional method for inspecting the inner surface of pipe material is to detect defects on the inner surface by propagating ultrasonic waves from the outer surface in the thickness direction of the pipe material, or to insert an interpolated eddy current flaw probe into the hole of the pipe material. In general, a technique of inserting into a wire and detecting flaws using eddy current has been applied.

Patent Document 1 proposes an apparatus for detecting eddy current at high speed while inserting an eddy current inspection probe into a hole of a straight pipe material.
However, the eddy current flaw detection using the interpolated probe disclosed in Patent Document 1 has a problem that the flaw detection performance is not sufficient, such as a crack that occurs on the inner surface can be easily detected, but a defect such as a closed surface is difficult to detect. It was.

For such a problem, there is a surface ultrasonic flaw detection method as a technique for detecting a closed defect whose surface side is closed with high accuracy. This excites an ultrasonic mode called surface ultrasonic wave that selectively propagates on the surface of the object, and the ultrasonic probe receives the reflection of the surface ultrasonic wave from the defect again and inspects for the presence of the defect. is there.
For example, in Patent Document 2, as an example of a surface ultrasonic flaw detection apparatus using surface ultrasonic waves, ultrasonic flaw detection is performed by exciting surface ultrasonic waves along the circumferential direction on the outer surface of a cylindrical or columnar inspection object. An apparatus is disclosed.

  The surface ultrasonic flaw detector described in Patent Document 2 requires a contact medium such as water between the flaw detection probe and the material to be inspected in order to introduce ultrasonic waves into the material to be inspected. Such a contact medium adheres to portions other than between the flaw detection probe and the material to be inspected. As described above, if the contact medium adheres to a portion other than the defect on the outer surface of the inspection object, the surface ultrasonic wave is reflected from the portion even though there is no defect, which may cause a false detection. The potential is great.

  Therefore, the technique in Patent Document 2 solves this problem by blowing off excess contact medium with an air flow.

JP 2004-251839 A JP 2000-214138 A

However, the technique described in Patent Document 2 is a technique that can be applied to the outer surface of the material to be inspected, and is difficult to apply as it is to the inner surface of the pipe material.
This is because, in order to discharge and remove excess contact medium (water or the like) in the hole of the pipe material, it is often extremely difficult to blow an appropriate air flow into the hole and blow off the contact medium.
Furthermore, in the inspection of the inner surface of a small-diameter pipe material, if excess water or the like is present, water is stretched in the circumferential direction in the hole due to the capillary phenomenon, which causes false detection of defects. A liquid contact medium cannot be applied to detect defects on the inner surface.

  In view of the above-described problems, an object of the present invention is to provide a pipe inner surface inspection apparatus that realizes surface ultrasonic flaw detection on the inner surface of a pipe material having a small inner diameter.

In order to achieve the above object, the present invention employs the following technical means.
The pipe inner surface inspection apparatus according to the present invention is a pipe inner surface inspection apparatus that detects defects on the inner surface of a pipe material to be inspected using ultrasonic waves, and the pipe material causes a capillary phenomenon in a hole. An insertion probe that has an inner diameter that can be inserted into the hole of the pipe material and that has a transmission / reception surface that transmits and receives ultrasonic waves to and from the inner surface of the pipe material, and the insertion probe and the pipe A non-fluid contact medium disposed between the inner surface of the material and a pressing means for pressing the insertion probe against the inner surface of the pipe material so that ultrasonic waves can propagate through the non-fluid contact medium. It is characterized by having.

By using a non-fluid contact medium (dry coupling sheet) such as rubber instead of the liquid contact medium, ultrasonic waves can be transmitted and received, and the surplus contact medium is not an inner surface defect. Therefore, it is possible to detect defects on the inner surface of a pipe material having an inner diameter that can cause capillary action in the hole.
The dry coupling sheet is a sheet of rubber or the like having a predetermined thickness.

As a means for pressing the dry coupling sheet, it is preferable that an urging means provided between the surface opposite to the transmitting / receiving surface of the insertion probe and the inner surface of the pipe member is provided.
The pressing means includes an airbag member disposed between a surface opposite to the transmitting / receiving surface of the insertion probe and an inner surface of the pipe member, and an air capable of supplying gas to the interior of the airbag member. You may have a supply means.

Further, it is preferable that the pressing means includes a magnetic adhesion means provided on the insertion probe and capable of being attracted to the inner surface of the pipe member facing the transmission / reception surface of the insertion probe.
By these pressing means, the insertion probe can be pressed against the inner surface of the pipe material with an appropriate pressure, and the ultrasonic wave introduction efficiency between the insertion probe and the pipe material is kept high.
The ultrasonic waves are preferably surface ultrasonic waves.

  Further, the inner diameter of the pipe material may be 20 mm or less.

  According to the present invention, the pipe material has a small diameter by having a pressing means for pressing the insertion probe against the pipe material so that the ultrasonic wave can propagate to the inner surface of the pipe material through the non-fluid contact medium. However, stable inner surface flaw detection is possible.

1 is an overall configuration diagram of a pipe inner surface inspection apparatus according to the present invention. It is the cross-sectional view and longitudinal cross-sectional view which show the pipe inner surface inspection apparatus of 1st Embodiment. It is a figure which shows the ultrasonic waveform of an ultrasonic flaw detection. It is the cross-sectional view and longitudinal cross-sectional view which show the press means of 2nd Embodiment. It is the cross-sectional view and longitudinal cross-sectional view which show the press means of 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
1 to 3 show a pipe inner surface inspection apparatus 1 according to a first embodiment of the present invention.
The pipe inner surface inspection apparatus 1 detects a defect K on the inner surface of a pipe material W (test tube material) to be inspected using ultrasonic waves, and can be inserted into a hole of the pipe material W. The ultrasonic wave can propagate through the insertion probe 2, the non-fluid contact medium 3 disposed between the insertion probe 2 and the inner surface of the pipe material W, and the non-fluid contact medium 3. In this way, it has pressing means 4 for pressing the insertion probe 2 against the inner surface of the pipe material W.

As shown in FIG. 1, the pipe inner surface inspection apparatus 1 includes a holding bar 11 having an insertion probe 2 attached to one end 11a, and the holding bar 11 moving in and out of the pipe material W in the tube axis L direction. A moving mechanism 12 that rotates around the tube axis L of W and a monitor 13 that displays an ultrasonic waveform detected by the insertion probe 2 are provided.
The pipe material W is a metal pipe material such as a seamless steel pipe, and the inner diameter of the pipe material W is formed to a small diameter of 20 mm or less.

When a liquid contact medium (water, glycerin, etc.) leaks from the insertion probe 2 into the hole of such a small diameter pipe material W, a capillary phenomenon occurs in the hole, and the circumferential direction of the inner surface of the pipe material W The detection of the defect K on the inner surface is hindered by water or the like.
Therefore, in the present invention, the above-described non-fluid contact medium 3 (dry coupling sheet) is used in place of the fluid liquid medium such as water or glycerin used in the detection of the defect K by normal surface ultrasonic waves. Is used.

Strictly speaking, whether the capillary phenomenon occurs depends on the surface tension and density of the liquid put into the hole of the pipe material W and the wettability of the inner surface of the pipe material W in addition to the inner diameter of the pipe material W.
[Interpolation probe 2]
The insertion probe 2 is a cylindrical body having a cross-sectional shape that can be inserted into a hole of the pipe material W, and transmits and receives surface ultrasonic waves (Rayleigh waves) to and from the inner surface of the pipe material W.

As shown in FIG. 2 (a), the insertion probe 2 has a piezoelectric element 14 and a side that abuts on the pipe material W in the insertion probe 2 (hereinafter referred to as "transmission / reception surface 2a" side). ) And a dry coupling sheet 3 disposed between the transmission member 15 and the inner surface of the pipe material W.
The transmission / reception surface 2a is formed to be curved along the inner surface of the pipe material W.

The piezoelectric element 14 is configured by sandwiching a piezoelectric body exhibiting a piezoelectric effect between electrodes. The piezoelectric element 14 can be vibrated at a predetermined frequency by applying a signal voltage to the electrode, and at the same time converts external vibration into voltage. The piezoelectric element 14 is connected to a control unit (not shown) outside the pipe material W and the monitor 13 via a cord 14a.
The transmission member 15 is a wedge-shaped, that is, a columnar member having a substantially right-angled triangular section, and is opposed to the vibration direction of the piezoelectric element 14 on one side surface (a surface corresponding to the hypotenuse of the right-angled triangle) and A piezoelectric contact portion 15 a that is in contact with 14 is formed. On the other side surface (the surface corresponding to the bottom of the right triangle) that is the transmission member 15, a sheet contact portion 15 b that contacts and transmits vibration from the piezoelectric element 14 to the dry coupling sheet 3 is formed. .

Therefore, the transmission member 15 performs vibration transmission between the piezoelectric element 14 and the dry coupling sheet 3.
[Dry coupling sheet 3, pressing means 4]
The dry coupling sheet 3 is made of a material such as rubber, and the sheet thickness is about 0.1 mm. When appropriate pressing is performed on the dry coupling sheet 3, the dry coupling sheet 3 is crushed between the insertion probe 2 and the pipe material W, and the vibration of the piezoelectric element 14 is transmitted to the pipe material W side. It is possible to introduce Rayleigh waves on the inner surface.

At this time, if the insertion probe 2 is pressed against the pipe material W and the contact pressure against the dry coupling sheet 3 is not appropriate, the efficiency of transmitting the vibration of the piezoelectric element 14 to the pipe material W is reduced. A pressing means 4 is required to keep the contact pressure pressed against the inner surface of W properly.
As shown in FIGS. 2A and 2B, as the pressing means 4, the side opposite to the transmitting / receiving surface 2 a of the insertion probe 2 (the back surface 2 b side of the insertion probe 2) and the inner surface of the pipe material W are used. The urging means 5 (pressing spring) is disposed between the pipe member W (strictly speaking, the inner surface opposite to the side on which the insertion probe 2 is pressed).

The push spring 5 is a coiled torsion spring, and one end 5 a is fixed to the back surface 2 b of the insertion probe 2, and the other end 5 b is in contact with the inner surface of the pipe material W to support the push spring 5. A support 16 is provided.
The spring support portion 16 is a plate member that is curved along the inner surface of the pipe material W. The spring support portion 16 is fitted to the inner peripheral surface of the pipe material W to support the other end 5b of the push spring 5, and the push spring 5 is appropriate. It supports that the insertion probe 2 is pressed against the inner peripheral surface of the pipe material W by pressure.

With this configuration, even when the inner diameter of the pipe material W is too small and a finger or the like is inserted into the hole and the insertion probe 2 cannot be pressed, it can be pressed with an appropriate pressure.
Further, the inner surface side surface of the pipe material W of the spring support portion 16 is subjected to Teflon (registered trademark) processing or the like, and the spring support portion 16 supports the other end 5b of the push spring 5 while supporting the pipe 5 It can slide with respect to the inner surface of the material W.
[Holding bar 11, moving mechanism 12, etc.]
The holding bar 11 is a bar inserted from one opening of the pipe material W, and the insertion probe 2 is attached to one end 11 a of the holding bar 11.

The mounting position of the holding bar 11 with respect to the insertion probe 2 is such that when the transmission / reception surface 2a of the insertion probe 2 is pressed against the inner surface of the pipe material W, the rod axis L ′ of the holding bar 11 is the pipe of the pipe material W. It is set so as to substantially coincide with the axis L.
The moving mechanism 12 is provided on the other end 11b side of the holding bar 11 exposed from the pipe material W, and an exit / retreat drive unit 17 that moves the holding bar 11 in and out of the pipe material W in the tube axis L direction. And a rotation drive unit 18 that rotates around the tube axis L of the pipe material W.

  The exit / retreat drive unit 17 includes a pair of rolls 17a and 17b that sandwich the holding bar 11 and a drive unit (not shown) that rotationally drives the rolls 17a and 17b. The shafts of both the rolls 17a and 17b are arranged substantially parallel to the radial direction of the pipe material W, and the retracting drive unit 17 is inserted into the hole of the pipe material W by the rotation of the rolls 17a and 17b. Or the insertion probe 2 can be withdrawn and retracted along the tube axis L within the hole of the pipe material W.

Similarly, the rotational drive unit 18 includes a pair of rolls 18a and 18b that sandwich the holding bar 11 and a drive unit (not shown) that rotationally drives the rolls 18a and 18b. It differs from the retracting drive unit 17 in that it is arranged substantially parallel to the tube axis L of the pipe material W.
Therefore, the rotation drive unit 18 rotates the rolls 18a and 18b so that the insertion probe 2 rotates around the tube axis L in the hole of the pipe material W while keeping the transmission / reception surface 2a along the inner surface of the pipe material W. Can be rotated.

The monitor 13 is a display that displays (A scope display) the ultrasonic wave transmitted from the insertion probe 2 to the pipe material W and the waveform of the ultrasonic wave propagated from the pipe material W to the insertion probe 2 side.
The horizontal axis when displaying the waveform indicates time (propagation distance), and the vertical axis indicates the echo intensity transmitted / received by the piezoelectric element 14. Pulses transmitted from the piezoelectric element 14 by the monitor 13 and defects are displayed. The time T until the light returns after being reflected by K can be read from the horizontal axis.
[Detection result of pipe inner surface inspection apparatus 1]
FIG. 3 shows a result of detecting a slit-like defect K having a depth of 50 μm applied to the inner surface of the pipe material W having an inner diameter of 8 mm, for example, by the pipe inner surface inspection apparatus 1 according to the first embodiment.

On the rightmost side of FIG. 3, the transmission pulse P1 accompanying the transmission of the Rayleigh wave from the interpolation probe 2 rises (that is, is observed), and on the right side (left and right center in FIG. 3) of the transmission pulse P1 is a defect K. The defect echo (defect pulse) P2 reflected by is observed.
Further, on the right side (leftmost side in FIG. 3) of the defect pulse P2, the transmission pulse P1 is transmitted along the inner surface of the pipe material W (see “surface ultrasonic wave propagation path” in FIG. 2), A circular pulse P3 that has been made one round and received again by the interpolation probe 2 is observed.

By reading the scale on the horizontal axis from the transmission pulse P1 to the defect pulse P2, the time T (unit: seconds) until the transmission pulse P1 is reflected by the defect K and returned.
By applying the second speed of the Rayleigh wave to 1/2 of this time T, the distance of the defect K from the transmission / reception surface 2a of the insertion probe 2 (specifically, the distance along the circumferential direction on the inner surface of the pipe material W) is increased. Obviously, considering the position of the insertion probe 2 in the pipe material W from the moving mechanism 12, the position of the defect K on the inner surface of the pipe material W can be specified.
[Flaw detection range of pipe inner surface inspection apparatus 1]
The range in which the position of the defect K can be specified will be described below.

The defect pulse P2 requires a round-trip time to be observed by the interpolation probe 2, whereas the position at which the circular pulse P3 is observed is the position of the propagation time for one round.
Therefore, the defect K at a position that is exactly 180 ° opposite to the portion of the inner surface of the pipe material W that is in contact with the insertion probe 2 is overlapped with the circulation pulse P3 by the defect pulse P2 reflected by the defect K. Not suitable for.

For this reason, the flaw detection range by Rayleigh waves is preferably less than half of the inner circumference of the pipe material W, preferably about 1/3 to 1/4 of the circumference.
Therefore, it is preferable to repeat the flaw detection by changing the circumferential position of the insertion probe 2 several times by the rotation drive unit 18 of the moving mechanism 12.
Further, the width in which the position of the defect K can be specified in the direction of the pipe axis L of the pipe material W is the width of the front and rear of the dry coupling sheet 3 that can receive the transmitted transmission pulse P1 and the reflected defect pulse P2 (tube axis). Length in the L direction).

Therefore, after detecting a defect at a predetermined position (for example, an opening edge of the pipe material W) in the pipe axis L direction of the pipe material W, the insertion probe 2 is moved to the tube axis by the retracting / driving unit 17 of the moving mechanism 12. The flaw detection may be repeated while shifting little by little along the L direction (from the opening edge of the pipe material W toward the back).
In the case of flaw detection (surface defect detection) using Rayleigh waves with pipe materials W such as seamless steel pipes as inspection targets, the circular pulse P3 can be observed even in a normal portion, so that Rayleigh waves are normally applied to the inner surface of the pipe material W. You can always check if it has been introduced.

In addition, noise scattering components due to the unevenness of the inner surface of the pipe material W are observed between the pulses P1 to P3. When the unevenness of the inner surface is sufficiently small, such a high S / N is realized. it can.
[Second Embodiment]
FIG. 4 shows the pressing means 4 of the pipe inner surface inspection apparatus 1 according to the second embodiment.

The second embodiment is characterized in that an air bag is used as the pressing means 4 instead of the pressing spring 5 used in the first embodiment.
Specifically, in the pipe inner surface inspection apparatus 1, an air bag member 6 is provided between the insertion probe 2 and the inner surface of the pipe material W, and an air supply means capable of supplying gas into the air bag member 6. 7 is also provided.

The airbag member 6 is a balloon body that can be expanded and contracted by supplying gas therein, and is disposed between the back surface 2 b of the insertion probe 2 and the inner surface of the pipe material W.
The air supply means 7 is an intake / exhaust pump that sucks air into the air bag member 6 and exhausts air from the air bag member 6 via an air tube 7 a communicating with the air bag member 6.
Therefore, by inflating the airbag member 6, the insertion probe 2 can be pressed against the inner surface of the pipe material W in the same manner as the pressing spring 5 of the first embodiment.

Further, since the amount of gas sent into the airbag member 6 can be adjusted by the air supply means 7, the force with which the airbag member 6 presses the insertion probe 2 against the inner peripheral surface of the pipe material W is appropriately adjusted. It is also possible to do.
Further, when the flaw detection range of the insertion probe 2 is shifted, after the gas in the airbag member 6 is once discharged by the air supply means 7 and the insertion probe 2 is moved back and forth and rotated by the moving mechanism 12. Then, the gas in the airbag member 6 is sucked again.

Other configurations of the second embodiment are the same as those of the first embodiment.
[Third Embodiment]
FIG. 5 shows the pressing means 4 of the pipe inner surface inspection apparatus 1 according to the third embodiment.
The feature of the third embodiment is that the pressing means 4 is attracted to the inner surface of the pipe material W (the inner surface of the pipe material W on the side where the insertion probe 2 is pressed) facing the transmission / reception surface 2a of the insertion probe 2. This is the point that the magnetizing means 8 is provided in the insertion probe 2.

This magnetic attachment means 8 is used when the pipe material W is a magnetic body, and is provided via support members 19 before and after the insertion probe 2 (in the direction of the pipe axis L of the pipe material W). A pair of electromagnets 8.
Since the electromagnet 8 is proportional to the current flowing through the attracting force on the inner surface of the pipe material W, it can be pressed to keep Rayleigh wave introduction efficiency high by flowing an appropriate current.

As a result, the electromagnet 8 is driven only when a pressing force is required, such as when transmitting / receiving Rayleigh waves from the insertion probe 2, thereby pushing the insertion probe 2 against the inner surface of the pipe material W with an appropriate pressure. I can hit it.
Other configurations of the third embodiment are the same as those of the first embodiment.
The present invention is not limited to the embodiment described above. Each configuration of the pipe inner surface inspection apparatus 1 or the like, or the overall structure, shape, dimensions, and the like can be appropriately changed in accordance with the spirit of the present invention.

The insertion probe 2 is a substantially cylindrical body, but may be a substantially ellipsoid or the like if it can be inserted into the hole of the pipe material W and has the transmission / reception surface 2a along the inner surface.
The dry coupling sheet 3 that is a non-fluid contact medium is not limited to rubber, but may be a high-molecular polymer having elasticity such as soft plastic as long as it can transmit ultrasonic waves.

The thickness of the dry coupling sheet 3 is not limited to 0.1 mm, but may be approximately 0.1 to 0.5 mm as long as ultrasonic waves can be propagated.
The urging means 5 is not limited to a push spring, but may be a leaf spring, a bamboo spring, or the like.

DESCRIPTION OF SYMBOLS 1 Pipe inner surface inspection apparatus 2 Interpolation probe 2a Transmission / reception surface of an interpolation probe 3 Non-fluid contact medium (dry coupling sheet)
4 Pressing means 5 Energizing means 6 Air bag member 7 Air supply means 8 Magnetic adhesion means W Pipe material K Defect on inner surface of pipe material

Claims (6)

A pipe inner surface inspection device for detecting defects on the inner surface of a pipe material to be inspected using ultrasonic waves,
The pipe material is formed with an inner diameter capable of causing capillary action in the hole,
An insertion probe that can be inserted into the hole of the pipe material and includes a transmission / reception surface that transmits and receives ultrasonic waves to and from the inner surface of the pipe material;
A non-fluid contact medium disposed between the insertion probe and the inner surface of the pipe material;
A pressing means for pressing the insertion probe against the inner surface of the pipe material so that the ultrasonic wave can propagate through the non-fluid contact medium;
A pipe inner surface inspection device characterized by comprising:   2. The pipe according to claim 1, wherein the pressing unit includes an urging unit disposed between a surface of the insertion probe opposite to the transmission / reception surface and an inner surface of the pipe member. Inner surface inspection device.   The pressing means includes an airbag member disposed between a surface opposite to the transmission / reception surface of the insertion probe and an inner surface of the pipe member, and an air supply means capable of supplying gas into the airbag member. The pipe inner surface inspection device according to claim 1, wherein:   The said pressing means has the magnetic attachment means which can be adsorb | sucked to the inner surface of the pipe material which is provided in the said insertion probe and opposes the transmission / reception surface of an insertion probe. The pipe inner surface inspection apparatus according to 1.   The pipe inner surface inspection apparatus according to claim 1, wherein the ultrasonic waves are surface ultrasonic waves.   The pipe inner surface inspection apparatus according to claim 1, wherein an inner diameter of the pipe material is 20 mm or less.

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