JP2007527532A - Electromagnetic ultrasonic probe - Google Patents

Abstract

  The electromagnetic ultrasonic probe is arranged in such a way that it is directly adjacent to each other and parallel to the work surface (4) and has at least three permanent magnets (5, 6) having a substantially rectangular cross section. Comprising a body (1) with a magnetic system forming the inside. The center magnet (5) forms a vertically polarized wave with respect to the work surface (4), the side magnet (6) forms a horizontally polarized wave, and the center magnet (5) facing the work surface (4). A side magnet (6) faces a magnetic pole similar to the magnetic pole toward the central magnet (5). The concentrators (7) are placed away from each other and are in contact with the magnetic pole surface of the central magnet closest to the work surface. An inductance coil (8) is provided under the concentration device. The magnet is formed in a rectangular parallelepiped shape or an annular shape, and is incorporated in the form of a permanent magnet or an electromagnet, that is, a solenoid.

Description

  The present invention relates to inspection and measurement technology devices, and more particularly to an electromagnetic ultrasonic probe.

  An electromagnetic ultrasonic probe (EMAT) is known that includes a magnetic system formed of annular permanent magnets with alternating magnetic poles, at least three flat inductive coils, and three concentrators of ferromagnetic material. (See Russian Patent No. 2215939).

  However, existing probes have a high leakage flux, which causes a reduction in sensitivity. In this probe configuration, the majority of the magnetic flux flows through the air, overcoming the considerable resistance that prevents the required level of magnetic induction from being secured within the working zone.

  In addition, the main body, the cover, the base, two annular permanent magnets having magnetic poles that are directly adjacent to each other and disposed on the outer surface and the inner surface, and the inner magnetic pole that is installed on one of the end faces Also known is an EMAT consisting of a magnetic system formed by a single round permanent magnet facing by a similar magnetic pole. This EMAT also comprises an inductance coil and a cylindrical concentrator formed coaxially with a round permanent magnet made of a ferromagnetic material (see Russian application No. 2003072424).

  By creating a common inner pole within the working zone, the known EMAT increases magnetic induction, resulting in enhanced inspection sensitivity.

  However, this known EMAT has a narrow inspection zone limited to 10-12 mm. In order to continuously inspect the entire surface of the object to be inspected, a plurality of probes must be arranged in a plurality of rows on the periphery of the object. Cost will rise significantly.

  In addition, a main body having a work surface to be directed to a side surface to be inspected, a magnetic system disposed in the main body to form a permanent magnet magnetic field, a magnetic field concentrator interlocking with the magnetic system, and a flaw detection pulse are generated. Also known is an EMAT consisting of an inductance coil arranged to receive a reflected pulse. This EMAT has a magnetic system in the form of a magnetic core surrounded on all sides by a permanent magnet with a similar magnetic pole facing inward, except on the side facing the working surface. The magnetic cores are formed as a plurality of electrical steel plates and are separated by spacers having functions of electrical insulation and sound insulation on the axis of symmetry. The working portion of the magnetic core is formed as a trapezoid whose small base faces the working surface. This EMAT comprises two inductance coils, one for flaw detection and the other for receiving reflected pulses (see RF, U, 31305).

  This variant of EMAT is characterized by a high labor input in the production of the magnetic core, as it requires application to plate end face cutting, milling and cleaning operations, spacer manufacturing, painting and varnishing operations. Permanent magnets that surround the magnetic core on the periphery create sites of increased reluctance at the location of their seams, which causes the generation of substantial leakage flux.

In addition, this known EMAT has a narrow inspection zone, similar to the one described above, and rotates a group of EMAPs around the surface of the bar to be inspected when realizing continuous inspection of the object to be inspected. In order to use additional equipment.
Russian Patent No. 2215939 Russian application No. 2003120724 RF, U, 31305

  The object of the present invention is to achieve an electromagnetic ultrasonic probe that has small dimensions that can increase the efficiency and profitability of ultrasonic inspection of objects in use, and that is sensitive and can be characterized by a very wide inspection band There is to do.

  The object is to have a body with a working surface intended to be directed towards the object to be examined, a magnetic system for forming a permanent magnetic field within the body, and a magnetic field concentrator that cooperates with the magnetic system. In an electromagnetic ultrasonic probe comprising an inductance coil adapted to form a flaw detection pulse and receive a reflected pulse, according to the invention, the magnetic systems are directly parallel to each other in parallel to the work surface. Includes at least three permanent magnets with rectangular cross-sections disposed in adjacent bodies, the center magnet forms a vertical polarization with respect to the work surface, the side magnets form a horizontal polarization, and the center magnet is operated Each concentrating device is in contact with the surface of this magnetic pole with respect to the work surface, and each concentrating device is placed away from each other and is most In contact country, by the inductance coil is mounted below the concentrator, the purpose is achieved.

  The magnet can have a rectangular parallelepiped shape or an annulus.

  In the latter case, the magnet can be formed of an electromagnet-solenoid.

  In one embodiment, the magnet can be formed of segments fastened by a tie.

  To reduce leakage flux, it is beneficial to place a ferromagnetic plate on the surface of the magnetic system, the plate being on the opposite side of the surface to the working surface.

  In order to increase the sensitivity of the probe, the concentrator is preferably formed from carbonyl iron powder impregnated with a compound.

  In order to reduce the possibility of inducing eddy currents in the magnet material, it is beneficial to provide a spacer of conductive material between each surface of the facing magnet pair and the concentrator.

  In a preferred embodiment, the space between the concentrator and the inductance coil is filled with a compound to enhance the structure of the probe.

  The invention is further illustrated by the description of specific embodiments and the drawings.

  1 to 3 show an electromagnetic ultrasonic probe including a main body 1 having a base 2 and a cover 3, and the bottom surface of the base 2 is a working surface 4 of the probe. The magnetic system is constituted by at least three permanent magnets 5, 6, which in the embodiment have a substantially rectangular cross-section arranged in the body 1 in close proximity to and parallel to the work surface 4. Formed in the body 1. In the described embodiment of the probe, the permanent magnets 5, 6 have a rectangular parallelepiped shape. The central magnet 5 forms vertical polarization, each side magnet 6 forms horizontal polarization, and each side magnet 6 has a magnetic pole similar to the magnetic pole of the central magnet 5 facing the work surface 4 (in this case). Faces the central magnet 5 with the “S” pole). The magnetic field concentration device 7 is arranged at a predetermined distance from each other, contacts the work surface 4 with the nearest surface of the central magnet 5, and an inductance coil 8 is attached below the concentration device 7. The inductance coil 8 is used for forming a flaw detection pulse and receiving a reflected pulse from an inspection object. The concentration device 7 is made of, for example, carbonyl iron powder impregnated with a compound such as an epoxy resin.

  A plate 9 of ferromagnetic material is arranged on the surface of the magnetic system opposite to the surface facing the work surface 4. A ceramic plate 10 is disposed under the inductance coil 8 in the plane of the work surface 4. A space between the concentration device 7 and the inductance coil 8 is filled with the compound 11. A connector 12 is installed in the cover 3, and the cover 3 and the base 2 are fastened to the main body 1 using screws 13.

  In the EMAT embodiment shown in FIGS. 4-7, unlike the one described above, the magnetic system is made in the form of a segment having an annulus and in the example surrounded by a tie 16 of non-magnetic material. It is formed by three permanent magnets 14 and 15. The magnets 14, 15 can also be configured as a plurality of integrated parts. Both permanent annular magnets and electromagnet-solenoids can be used as magnets 14,15. The permanent annular magnets 14, 15 are arranged directly adjacent to each other in the cylindrical body 17, so that the central magnet 14 (FIG. 5) forms a radial (vertical in cross section) polarization and the side magnets 15 are In this example, each side magnet 15 has an N pole similar to the “N” pole of the central magnet 14 facing the work surface 18 having a cylindrical shape. Facing the central magnet. Ceramic rings 19 formed of segments 20 concentrically with the central magnet 14 are arranged at regular intervals along the circumference. The inductance coil 8 is glued to the segment 20 and the concentrating device 7 is glued to the inductance coil surface facing the magnets 14, 15. In this embodiment of the EMAT, the space between the inductance coil 8 and the concentration device 7 is filled with the compound 11 as described above. The ring 19 is held in the cylindrical body 17 by the intermediate sleeve 21 with the grooves 22 formed at regular intervals in a circle (FIG. 7). The groove 22 has an inner recess 23, and the segment 20 is bonded to the inner peripheral surface thereof.

  Since eddy currents in the material forming the annular magnets 14 and 15 affect the quality of the EMAT operation, in order to prevent this eddy current, a spacer 24 made of a conductive material such as foil is provided on the surface of these magnets. And the outer surface of the intermediate sleeve 21.

  The intermediate sleeve 21 provided with the ring 19 is fixed by flanges 25, 26, 27, 28 and 29 made of nonmagnetic material, which are fastened to the main body 17 with bolts 30 and 31 from the end face.

  In order to lay the lead wire 32 (FIG. 4) of the inductance coil 8, a laying groove 33 is provided in the intermediate sleeve 21 through the groove 22. Further, an electrical connector 34 is installed on the main body 17 in order to connect the probe to the power source.

  The EMAT embodiment shown in FIGS. 1-3 is most convenient for realizing ultrasonic quality inspection of flat objects such as steel plates, rolled metals and the like.

  In an actual embodiment of ultrasonic inspection, the probe is close to this object in such a way that its working surface 4 is directed to the surface of the object to be examined, and the magnetic field of the probe It is installed at a distance that can cover the entire area. Thus, the magnetic field is closed in the metal. The inductance coil 8 is excited with a flaw detection pulse of a predetermined frequency that induces ultrasonic fluctuations in the test object, and that fluctuation in the permanent magnetic field of the probe magnetic system is converted into an alternating magnetic field. The This alternating magnetic field induces an alternating current in the inductance coil 8, which is received in the form of an electrical signal by a receiver (not shown). The size and coordinates of the defect are determined by the ratio between the reflected pulse from the defect and the reference (flaw detection) pulse.

  The proposed configuration of the probe magnetic system is shown in FIG. 8 where maximum concentration of field lines is observed under the central magnet 5 in the working gap “C”. To achieve maximum guidance. In practice, the investigation shows that the entire magnetic flux created by the magnets 5, 6 is concentrated in the area where the inductance coil 8 is located, which achieves a high level of signal reflected from defects in ultrasonic inspection.

  Application of carbonyl iron powder to the concentrator 7 eliminates eddy currents therein that would distort the signal.

  By installing the ferromagnetic material plate 9 on the surfaces of the magnets 5 and 6, loss of magnetic flux due to leakage is reduced, and reception of a higher level signal is enabled.

  By installing a number of inductance coils 8 under the central magnet 5 over substantially the entire length, the probe inspection band can be basically extended.

  The second EMAT embodiment shown in FIGS. 4-7 is primarily for use in ultrasonic inspection of bars. This EMAT provides a multi-channel configuration in which the inductance coils 8 are arranged radially with respect to the inspection object 35, in particular, a bar member that can be passed through the openings in the annular magnets 14 and 15 during the inspection.

  As can be seen from FIG. 5, the radial arrangement of the inductance coil 8 on the inner surface of the permanent annular magnet or electromagnet-solenoid relative to the surface of the test object 35 achieves virtually 100% (continuous) inspection of the test object. Enable. In particular, in ultrasonic inspection of a bar having a diameter of 95 mm using the EMAT, the entire inspection area of 120 mm in a circle is achieved by the inductance coil 8 according to the present invention.

  For ultrasonic inspection of rods of other diameters, EMATs can be made with similar numbers but different numbers and sizes of inductance coils and magnets or electromagnet-solenoids.

  If it is necessary to achieve 100% including the reserve, another EMAT that is similar to the first but slightly different can be placed in the course of the examination object.

  This small EMAT embodiment provides a wide inspection area and can replace four or more single-channel four EMATs that cannot be aligned in one plane for manufacturing reasons. is there.

  This EMAT embodiment, similar to that described above, is because all the magnetic flux generated by the magnets 14, 15 is concentrated in the working gap “C” under the inductance coil 8 illustrated in FIGS. It is characterized by high sensitivity.

  Yet another advantage of this EMAT embodiment is that the tracking mechanism required to bring the EMAT closer to the surface of the bar to be inspected and to remove the EMAT upon completion of the inspection is an ultrasonic inspection in the bar inspection. It is not in the configuration of the device.

  The electromagnetic ultrasonic probe implemented by the present invention is mainly used in an apparatus for ultrasonic nondestructive quality inspection of materials and objects, particularly high-quality rolled metal, steel plate and bar.

1 is a top view of an electromagnetic ultrasonic probe according to the present invention of a first embodiment. FIG. 2 is a cross-sectional view of the same electromagnetic ultrasonic probe as in FIG. 1 taken along line II-II in FIG. 1 (the upper surface cover is conditionally removed). FIG. 3 is a cross-sectional view of the same electromagnetic ultrasonic probe as in FIG. 1 taken along line III-III in FIG. 1. It is a side view by the arrow A of FIG. 5 of the electromagnetic ultrasonic probe of this invention in 2nd Embodiment. FIG. 5 is a cross-sectional view of the same electromagnetic ultrasonic probe as in FIG. 4 taken along line V-V in FIG. 4. FIG. 6 is a cross-sectional view of the same electromagnetic ultrasonic probe as in FIG. 4 taken along line VI-VI in FIG. 5. FIG. 6 is an enlarged view of a portion “B” in FIG. 5. It is a figure which shows the distribution pattern of the magnetic field force line about EMAT embodiment shown by FIGS. FIG. 8 shows the distribution pattern of magnetic field lines for the EMAT embodiment shown in FIGS. 4-7, wherein the magnetic system is built on a permanent magnet. It is a figure which shows the distribution pattern of the same magnetic field force line as FIG. 9 at the time of comprising a magnetic system based on an electromagnet solenoid.

Claims (9)

  A main body (1) having a work surface directed toward the inspection object side, a magnetic system in the main body (1) for forming a permanent magnetic field, and a magnetic field concentration device (7) cooperating with the magnetic system; An electromagnetic ultrasonic probe comprising an inductance coil (8) adapted to form a flaw detection pulse and receive a reflected pulse, wherein the magnetic system is parallel to the work surface (4) and directly adjacent to each other Including at least three permanent magnets (5, 6) arranged in the body (1) and having a rectangular cross section, the central magnet (5) forming a vertical polarization with respect to the work surface (4), The side magnet (6) forms a horizontally polarized wave, and the side magnet (6) faces the center magnet (5) with the same magnetic pole as the pole facing the work surface (4) of the center magnet (5). And the concentration device (7) is installed away from each other, To have the closest, electro-magnetic acoustic transducer, characterized in that the inductance coil (8) is attached beneath the concentrator.   The electromagnetic ultrasonic probe according to claim 1, wherein the magnets (5, 6) have a rectangular parallelepiped shape.   2. The electromagnetic ultrasonic probe according to claim 1, wherein the magnets (5, 6) have an annular shape.   The electromagnetic ultrasonic probe according to claim 3, wherein the magnet is an electromagnet-solenoid.   The electromagnetic ultrasonic probe according to claim 3, wherein the magnets (14, 15) are formed of segments fastened by a binding tool (16).   6. Ferromagnetic plate (9) is placed on the surface of the magnetic system, the plate being on the opposite side of the surface towards the working surface (4). The electromagnetic ultrasonic probe according to item.   7. The electromagnetic ultrasonic probe according to claim 6, wherein the concentrating device (7) is formed from carbonyl iron powder impregnated with a compound.   Electromagnetic ultrasonic probe according to claim 7, characterized in that a spacer (24) of conductive material is placed between the surface of the facing magnets (14, 15) and the concentrator (7). Child.   9. The electromagnetic ultrasonic probe according to claim 8, wherein the space between the concentrating device (7) and the inductance coil (8) is filled with the compound (11).

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