JPS60202355A - Eddy current flaw detection - Google Patents

Abstract

PURPOSE:To enhance the detection accuracy of the titled probe device, by providing a container made of a non-magnetic material having a cooling liquid received therein to the free end part of a probe main body in a liquid-tight state and forming the part opposed to the recessed groove formed to the end surface of the free end part of said container from a non-magnetic metal foil while securing the central part of said foil to an inner wall surface. CONSTITUTION:An eddy current flaw detection probe apparatus 12 is formed of a magnetic material and has a plurality of probe main bodies 14 protruded to the side of flat steel 10 and a yoke part 15 connecting the base end parts of said main bodies 14. The free end parts of the main bodies 14 are formed as magnetic pole parts, and exciting coils 16 and detection coils 18 are secured thereto in a wound state. U-shaped pierced recessed grooves 20 are respectively formed to the leading end parts of the main bodies 14 in a direction crossing mutually parallel side surfaces of the main bodies 14. The inner wall surfaces of the recessed grooves 20 function as flaw detection surfaces and opposed to each other so as to provide almost equal intervals to the surface to be inspected of the side edge part of the flat steel 10.

Description

[Detailed Description of the Invention] Technical Field This invention relates to an eddy current flaw detection probe device.
In particular, the present invention relates to a probe body in which a through-groove is formed into which a side edge of a longitudinal member to be inspected is fitted.

In conventional eddy current flaw detection, the flaw detection surface of the probe body is opposed to the surface to be inspected, and changes in the eddy current caused by the magnetic flux applied from the probe body to the inspected member are detected using a coil installed in the probe body. By detecting this, flaws existing on the inspected member are detected. For example, when detecting flaws on the convex side edge of a longitudinal inspected member, the flaw detection surface of the probe body is opposed to the side edge inspected surface, and the two are moved relative to each other in this state. Flaw detection is performed.

In this case, a through-groove is provided in the end face of the free end of the probe body so that the entire flaw detection surface of the probe body faces the entire surface to be inspected, and the side edge of the member to be inspected is fitted into the groove. By doing so, the gap between the inner wall surface of the concave groove as a flaw detection surface and the surface to be inspected becomes almost constant, and good detection sensitivity can be obtained, as disclosed in the patent application filed by the present applicant (Japanese Patent Application No.
10'380). When the coil wound around the probe body is wound along the opening edge of the groove mentioned above on the end face and side surface of the free end of the probe body, the coil is wound from the entire detection surface of the groove to the entire surface to be inspected. It has been made clear in the same application filed by the present applicant (Japanese Patent Application No. 58-28051) that magnetic flux is uniformly applied and high detection sensitivity can be obtained over the entire surface to be inspected. In such an eddy current flaw detection probe device,
Since the coil is wound around the free end end face and side surface of the probe body, the coil is firmly fixed to the surface of the probe body with an adhesive or the like.

However, it has been found that when the inspected member is a high-temperature member and hot flaw detection is performed, there is a problem in that the coil tends to peel off from the probe due to the influence of the heat. When a part of the coil separates from the probe, the separated part is vibrated by the vibrations applied to the probe, which becomes a source of noise and deteriorates detection accuracy, and its peeling can cause damage to the eddy current probe device. This will reduce the service life.
cause problems.

Purpose of the Invention The present invention aims to prevent the coil from peeling off from the probe in such an eddy current probe (IA probe device), thereby maintaining high detection accuracy of the probe and improving its service life. It is what was done.

Structure of the Invention In order to achieve this object, the present invention includes a box-shaped container made of a non-magnetic material containing a cooling liquid inside the free end of the probe, covering the free end. A portion of the container that is provided in a liquid-tight manner and that faces the groove formed on the end face of the free end is formed of a non-magnetic metal foil having a shape that follows the inner wall surface of the groove; It is characterized in that the central portion is fixed to the inner wall surface.

Effects of the Invention In such a flaw detection probe, the free end of the flaw detection probe is efficiently cooled by the cooling liquid inside the container. Therefore, even if the inspected member is a high-temperature member, expansion and contraction of the coil and the probe body are suppressed, thereby effectively suppressing separation of the coil from the probe body. This has the effect of maintaining high detection accuracy of the flaw detection probe and extending its service life. In addition, since the container is made of a non-magnetic material, and the part of the container that faces the free end of the probe is made of extremely thin metal foil, scratches can be detected by providing such a container. There is no change in performance.

Moreover, since the central portion of the metal foil is fixed to the inner wall surface of the groove, the rigidity required of the metal foil is reduced.
Thinner metal foils can be used and flaw detection sensitivity is maintained favorably.

Note that such a flaw detection probe has a feature that it can effectively prevent the generation of noise when the probe is exposed to water or the like. For example, when testing a component while rolling it, the probe is often exposed to spray from the rolling rolls, but the free end of the probe is covered by a box-shaped container. This prevents water splashes and the like from directly hitting the free end of the probe and the coil. When the free end of the probe and the coil are sprayed with water, etc., the detection characteristics change, which causes noise, but with the probe according to the present invention, the probe is not directly sprayed with water, etc. This prevents
The noise caused by this is prevented, and flaws can be detected with high sensitivity.

Embodiment Next, an embodiment of the present invention will be described in detail with reference to the drawings. .

FIG. 1 is a diagram showing the basic configuration of an eddy current flaw detection probe device 12, in which 10 is a longitudinal flat screen as a member to be inspected, which is made to run in the longitudinal direction via a hot rolling roller (not shown). It has become.

The eddy current flaw detection probe device 12 is made of a magnetic material, and includes a plurality of probe bodies 14 (three in this embodiment) protruding toward the flat steel 10 side, and a yoke portion 15 connecting the base ends of the probe bodies 14. have. The free end portion of the main body 14 is a magnetic pole portion, and an excitation coil 16 and a detection coil 18 are wound and fixed thereto. A U-shaped through recess 120 (see FIG. 2) is formed at the tip of each main body 14 in a direction intersecting the mutually parallel side surfaces 22 of the main body 14, and inside the recess groove 20, the flat steel 10 is inserted. The side edge portion 24 is adapted to be fitted. Concave groove 2
The inner wall surface of 0 is used as a flaw detection surface 26 and is opposed to the surface to be inspected of the side edge 24 of the flat steel 10 with a substantially equal gap therebetween. That is, flaw detection surface 2
The width W of the U-shaped groove 20 forming the groove 6 is set to the thickness T of the flat steel 10 plus twice the predetermined gap, and the depth of the U-shaped groove a20 is The radius D is set to be sufficiently larger than the radius of curvature R of the side edge 24, so that the side edge 24 can be deeply penetrated into the groove 20, and the entire surface of the flaw detection surface 26 is covered with the side edge 24 to be inspected. They are arranged to face each other at the predetermined distances from each other at approximately equal angles.

The excitation coil 16 is wound along the opening edge of a U-shaped groove 20 formed in the probe body 14, and is fixed to the probe body 14 with an adhesive in this state. That is, the coil 16 and the pair of mutually parallel side surfaces 2 of the main body 14
2, the U-shaped portion 28 is curved along the opening edge of the groove 20, and the U-shaped portion 28 is arranged along the opening edge of the concave a20 on the end face 30 and connects each end of the U-shaped portion 28. A pair of connecting portions 32 are separated from each other.

As shown in detail in FIGS. 3 and 4, each of the probe bodies 4 includes a container 34 made of a non-magnetic material that covers its free end and stores cooling water therein, and a container 34 that holds the same. A holder 36 is provided for the purpose. The holder 3G is liquid-tightly fixed to the probe body 14. On the back side of the holder 36, there is an inlet boat 38 for introducing cooling water.
and an outlet boat 40 for discharging cooling water, and cooling water passages 42, 44 communicating with the ports 1-38, 40 are provided therein.

The holder 3G also has a tip 14a of the probe body I4.
is fixed, while the holder 36 itself is detachably fixed to the proximal end portion 14b of the probe body 14 by a fixing means (not shown). That is, the holder 3G also constitutes a part of the magnetic circuit, and the container 3 fixed to the holder 36
4 and the tip 14a of the probe body 14 accommodated therein are easily convertible.

On the other hand, the container 34 has a box shape, and is liquid-tightly fixed to the holder 36 at its opening. The container 34 is the main body I4
It consists of a cylindrical part 4G that surrounds the outer periphery of the tip part 14a and a bottom part 48 that closes one opening of the cylindrical part 4G. The cylindrical part 4G is formed of a stainless steel plate with a thickness of approximately 2 mm, and forms a certain amount of space between it and the outer peripheral surface of the tip part 14a, and that space is connected to the cooling water passage of the holder 3G. 42,4
i to 4! l! The cooling water supplied from the inlet boat 38 is introduced into this space, or the cooling water introduced into the space is discharged to the outside. The bottom portion 48 is formed of stainless steel foil with a thickness of approximately Q, l*wa, and is disposed with a slight gap between it and the end surface of the free end portion of the main body 14. bottom 48
has a shape that follows the shape of the end face of its free end.

That is, the central portion thereof is bent into a U-shape along the inner wall surface of the U-shaped groove 20, and the U-shaped bent portion is curved into the groove of the main body 14. It is fixed to the wall with adhesive. Note that a large number of pores are formed in the adhesive layer 5° to allow the flow of cooling water.

These pores are naturally formed after the adhesive treatment, for example, when an epoxy resin is used as the adhesive. Of course, it is also possible to actively form pores using a pore-forming material or the like.

In the flaw detection probe 12 configured as described above, when an alternating current excitation current of several tens of kilohertz to several hundred kilohertz is applied to the excitation coil 16, the magnetic flux generated is transferred from the flaw detection surface 26 to the opposite flat surface. 6110. When such magnetic flux is applied to the flat steel 10,
Eddy currents are induced in the surface layer of the flat steel 10, and the magnetic flux generated by the eddy currents is detected by the detection coil 18. The magnetic flux generated by eddy current changes when there is a flaw in the surface layer of the flat steel, so by detecting this magnetic flux, the existence and size of the flaw can be detected. Moreover, in the flaw detection probe 12 described above, the magnetic pole portion is cut out in a U-shape, and the flaw detection surface 2 of the probe I2 is cut out.
6 is entirely opposed to the surface to be inspected with a constant gap therebetween, so that the flat steel side edge 24 can be inspected over a wide range. Furthermore, since the excitation coil 16° and the detection coil 18 are arranged along the surface of the flat steel side edge 24, magnetic flux is evenly applied to the flat steel surface, and magnetic flux generated by eddy currents is evenly detected. Therefore, scratches can be detected with high sensitivity.

By the way, in a flaw detection probe in which the coil is wound in this manner, as flaw detection is repeated, a portion of the coil 16 may come off from the surface of the probe 12, reducing measurement accuracy and shortening the service life. This causes problems. When the inspected member is at a high temperature, the flaw detection probe 12 is heated and expanded by the heat, and is also contracted when cooled. Moreover, the amount of thermal expansion between the probe body 14 and the coil 16 is large.

Because of the difference in the amount of contraction, if these are repeated, the adhesive bonding the coil 16 to the probe body 14 will be destroyed, and the coil 16 will be partially or completely peeled off. When the coil 16 is peeled off, the coil 16 vibrates and generates noise as described above, which reduces detection accuracy. Further, if the peeling progresses further, detection becomes impossible. In other words, the probe becomes unusable.

In contrast, in the eddy current flaw detection probe device 12 described above, the main body 14 is cooled by cooling water, so even if the inspected member is a high-temperature member, the temperature of the probe itself does not rise much. For this purpose, the probe body 14. The amount of thermal expansion or contraction of the coil 16 is small, so peeling of the coil 16 is suppressed, and detection accuracy is maintained at a high level forever, and its service life is also extended. Incidentally, the service life of conventional probe devices is 5
It has been confirmed that the time required for probe I2 is approximately 100 hours.

Moreover, in such an eddy current flaw detection probe device 12, °ζ,
The bottom part 48 of the container 34 is formed of a thin non-magnetic H metal foil, and the metal foil has a shape that follows the protruding end surface of the probe body 14, and there is a small gap between it and the 01;1 surface. Because these containers 34 are arranged facing each other with a gap between them,
By providing this, changes in the magnetic flux applied from the probe 12 to the flat steel 10 can be suppressed as much as possible. Therefore, the same detection sensitivity as when the cooling container 34 is not attached can be obtained.

In addition, in the probe 12, the protruding end of the main body 14 is covered with a container 34 and is cooled by the cooling water inside, but the free end is covered with the container 34. Based on this, a secondary effect arises that the detection accuracy is further increased. As mentioned above, there are many opportunities for the probe 12 to be exposed to water splashes from rolling rollers, etc., and when such water splashes on the probe 12, a phenomenon occurs that generates noise and reduces detection accuracy. Since the probe 12 is covered by the container 34, the probe 12 itself is not splashed with water. Of course, there is no risk of noise occurring due to such water dripping, and therefore the detection accuracy will not be reduced by the noise. Note that the above-mentioned circumstances are the same for the detection coil 18 as well.

Although the embodiments of the present invention have been described in detail above, the present invention can be implemented in other embodiments as well.

For example, as shown in FIG. 5, a groove 52 having a shape corresponding to the shape of the coil 16 is provided on the free end end surface 30 and side surface 22 of the probe body 14, and the inside of this groove 52 is provided as shown in FIG. It is also possible to apply the present invention to a probe body in which the coil 16 is fitted and fixed with adhesive. In this case, the coil 16 is connected to the groove 5.
Since the coil 16 is restrained by the bottom wall surface and side wall surface of the probe body 14, the coil 16 is further separated from the probe body 14
+t.

Further, the shape of the end surface of the protruding end portion of the probe can be made into an appropriate shape depending on the shape of the side edge portion of the inspection target portion. In this case, the shape of the bottom of the container that covers it is changed depending on the shape of its end surface. Furthermore, in the above embodiment, the center portion of the bottom is fixed to the end surface of the probe, but it is also possible to fix the entire bottom to the bottom of the probe, and in this case, the bottom can be fixed in spots. In other words, it is also possible to partially fix it.

Further, the container 34 may be made of non-magnetic material such as copper alloy or aluminum alloy, and in particular, the cylindrical portion 46 may be made of synthetic resin or porcelain. However, the bottom part 48 is required to be made of a thin material that does not affect detection sensitivity, has rigidity that can withstand a certain amount of water pressure and vibration, and has properties that allow it to be fixed liquid-tightly to the cylindrical part 46. , metal foil, especially a metal of the same type as the material of the cylindrical portion 46 is preferable. Here, the non-magnetic material refers to a material that does not affect the flaw detection performance, so long as it has a magnetic permeability of 10 or less. Further, metal foil refers to one having a thickness of 0.5 mm or less.

Furthermore, although cooling water is used in the embodiments described above, other fluids may be used, and although the bottom portion 48 of the container 34 is entirely made of a thin material, at least the portion facing the groove 20 It is sufficient if it is made of a thin material.

In addition, without departing from the spirit of the present invention, the present invention includes:
It is possible to implement the present invention with various modifications based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

Figure 1 shows the basic configuration of a flaw detection probe device, which is an embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing the magnetic pole part in FIG. 1 together with the excitation coil. FIGS. 3 and 4 are a perspective view and a sectional view of a main part, respectively, showing the free end of the probe shown in FIGS. 1 and 2 covered with a container. FIGS. 5 and 6 are perspective views of main parts of another probe to which the present invention is applied, respectively showing a state in which the coil is not fully wound and a state in which the coil is fully wound. 10: Flat steel (part to be inspected) 12: Eddy current flaw detection probe device 14; Probe body 16: Excitation coil 18: Detection coil 20: Through groove 24: Side edge 30: End face 34: Container 48: Bottom 50: Adhesive layer Applicant: Daido Steel Co., Ltd. Figure 1 Figure 3 @4 (fund) Average No. 5f3J ・

Claims (1)

[Scope of Claims] A probe body, a through-groove formed in the end face of the free end of the probe body for fitting the side edge of a longitudinal member to be inspected, and a penetrating groove formed along the opening edge of the groove. In the eddy current flaw detection probe device, the eddy current flaw detection probe device includes a coil wound in an annular shape and detects flaws existing on the side edge of the inspected member, the probe body having a box-like shape at the protruding end. A container made of a non-magnetic material that accommodates a cooling liquid inside is installed in a liquid-tight manner so as to cover the free end, and a portion of the container facing the groove formed in the end surface of the free end is provided. An eddy current flaw detection probe device comprising: a non-magnetic metal foil having a shape that follows the inner wall surface of the groove; and at least a central portion of the metal foil being fixed to the inner wall surface.