JP2010091493A - Barkhausen noise inspection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Barkhausen noise inspection system which prevents a surface of an object to be inspected from being damaged, even in the case a detecting head is slid on the surface of the object to be inspected. <P>SOLUTION: The detecting head 1 of the Barkhausen noise inspection system includes: an exciting coil 2 for magnetizing the object to be inspected 20; and a detecting coil 3 for detecting Barkhausen noise emitted by the magnetized object to be inspected 20, wherein at least portions of cores 4, 5 of the exciting coil 2 and the detecting coil 3, which contact with the object to be inspected 20, are applied with coatings 6, 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Barkhausen noise inspection apparatus that performs nondestructive inspection using Barkhausen noise.

Various Barkhausen noise inspection apparatuses using Barkhausen noise have been proposed as inspection apparatuses that perform nondestructive inspections such as grinding burn, residual stress, hardness, and load (for example, Patent Documents 1 to 3).
Japanese Patent Laid-Open No. 02-262958 JP 2001-133441 A JP 2006-266686 A

  In these Barkhausen noise inspection apparatuses, in order to detect Barkhausen noise with high sensitivity, the detection head is pressed against an inspection object. The detection head includes an excitation coil that magnetizes the inspection object and a detection coil that detects Barkhausen noise generated by the magnetized inspection object. The yoke of these coils is made of a ferromagnetic material such as ferrite or steel. It has been produced.

  When such a Barkhausen noise inspection apparatus is used for nondestructive inspection of the entire peripheral surface of a steel part such as a bearing, it is necessary to slide the detection head on the peripheral surface of the steel part. However, when the detection head is pressed against the peripheral surface of the steel part that is the object to be inspected, the excitation coil and the yoke of the detection coil are pressed against the steel part. There is a possibility.

  An object of the present invention is to provide a Barkhausen noise inspection apparatus that does not damage the surface of the inspection object even if the detection head slides on the surface of the inspection object.

A Barkhausen noise inspection apparatus according to the present invention includes a detection head having an excitation coil for magnetizing an inspection object and a detection coil for detecting Barkhausen noise generated by the magnetized inspection object. In the above, a coating is applied to at least a portion of the magnetic core of the excitation coil and the detection coil that is in contact with the inspection object.
According to this configuration, since at least a portion of the magnetic core of the excitation coil and the detection coil that is in contact with the inspection object is coated, the surface of the inspection object is scratched even if the detection head is slid on the surface of the inspection object. It can prevent sticking.

  In the present invention, the coating material may be, for example, an epoxy resin or a silicon elastic material. In this configuration, since the coating material is soft, it is possible to more effectively prevent the surface of the inspection object from being scratched.

In the present invention, the coating material may be magnetic.
If the material of the coating applied to the magnetic core of the exciting coil has magnetism, the magnetic resistance between the inspection object and the exciting coil magnetic core is reduced, so that the current required for magnetization of the inspection object is reduced. Also, in the case of the coating applied to the magnetic core of the detection coil, if the material is magnetic, the magnetic resistance between the object to be inspected and the detection coil magnetic core is reduced, so the detection sensitivity of Barkhausen noise is high. Become.
In this case, the coating material may be a nonmagnetic base material mixed with magnetic powder. Thereby, it is possible to achieve both the effect of preventing scratches and the effect of reducing magnetic resistance.

In the present invention, the Barkhausen noise inspection apparatus may be used for detecting information on the surface of the rolling device or the surface of the rolling device component. A rolling device refers to a device having rolling elements such as a rolling bearing, a ball screw, and a constant velocity joint, and the rolling device component is a component of the rolling device, such as a component having a rolling surface such as a bearing race. Say.
In this case, the surface information may be detected by bringing the detection head into sliding contact with the surface of the rolling device or the surface of the rolling device component. Further, the surface information to be detected may be, for example, surface grinding burn, residual stress, or a defect.

  A Barkhausen noise inspection apparatus according to the present invention includes a detection head having an excitation coil for magnetizing an inspection object and a detection coil for detecting Barkhausen noise generated by the magnetized inspection object. In this case, since at least a portion of the magnetic core of the excitation coil and the detection coil that contacts the inspection object is coated, the surface of the inspection object can be damaged even if the detection head is slid on the surface of the inspection object. Can be prevented.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic diagram of the Barkhausen noise inspection apparatus of this embodiment. This Barkhausen noise inspection apparatus includes a detection head 1 including an excitation coil 2 and a detection coil 3, and a signal processing unit 14 that performs signal processing on the detected Barkhausen noise to obtain surface information of the inspection object 20. At the time of inspection, the detection head 1 is pressed against the surface of the inspection object 20.

  The excitation coil 2 in the detection head 1 is a coil for magnetizing the inspection object 20 and is wound around a yoke 4 that serves as a magnetic core. The detection coil 2 in the detection head 1 is a coil for detecting Barkhausen noise generated by the magnetized inspection object 20, and is wound around a yoke 5 serving as a magnetic core. The yoke 4 of the exciting coil 2 is formed in a U-shape, and its front end surface is opposed to the inspection object 20. The yoke 5 of the detecting coil 2 is directly in the center of the leg pieces on both sides of the exciting coil 2. Is provided. The yokes 4 and 5 are made of a magnetic oxide such as ferrite or a laminated silicon steel plate. In a state where the detection head 1 is pressed against the surface of the inspection object 20, the yokes 4, 5 are pressed against the surface of the inspection object 20.

  An alternating current that generates an alternating magnetic field for magnetization is supplied from the power supply 15 of the signal processing unit 14 to the excitation coil 2. The detection coil 3 is connected to the Barkhausen noise detection circuit 16 of the signal processing unit 14. The Barkhausen noise detection circuit 16 is a circuit that extracts Barkhausen noise from the detection signal of the detection coil 3, and includes an amplifier circuit that amplifies the detection signal, a filter circuit that extracts Barkhausen noise from the amplified detection signal, and the like. Consists of.

  As shown in the front sectional view and the side sectional view in FIGS. 2 (A) and 2 (B), a coating 6 is applied to a portion of the yoke 4 around which the exciting coil 2 is wound that contacts the inspection object 20. In this case, the coating 6 may be applied to the entire surface of the yoke 4. Further, as shown in the front sectional view and the side view in FIGS. 3A and 3B, a coating 7 is also applied to a portion of the yoke 5 around which the detection coil 3 is wound that is in contact with the inspection object 20. . Also in this case, the coating 7 may be applied to the entire surface of the yoke 5. When the yokes 4 and 5 are made of steel or the like, the coatings 6 and 7 also serve as a rust preventive coating.

  The material of each of the coatings 6 and 7 is softer than the metal material used as the material of the inspection object 20 such as epoxy resin or silicon elastic material (fluorine rubber material), and scratches the metal material. The one without is used.

  Moreover, it is desirable that the material of each coating 6, 7 has magnetism. If the material of the coating 6 is magnetic, the magnetic resistance between the inspection object 20 and the yoke 4 becomes small, so that the current required for magnetization of the inspection object 20 becomes small. Also, in the case of the coating 7, if the material is magnetic, the magnetic resistance between the inspection object 20 and the yoke 5 becomes small, so that the detection sensitivity of Barkhausen noise increases. In order to give the coatings 6 and 7 magnetism, a material obtained by mixing magnetic powder into a nonmagnetic base material such as an epoxy resin or a silicon elastic material may be used as the material.

  FIG. 4 shows a more specific configuration example of the Barkhausen noise inspection apparatus. The detection head 1 is configured by installing a yoke 4 around which an excitation coil 2 is wound and a yoke 5 around which a detection coil 3 is wound in a cylindrical housing 8. The exciting coil 2 is wound around the yoke 4 via the winding frame 9, and the detection coil 3 is wound around the yoke 5 via the winding frame 10. The excitation coil 2 and the detection coil 3 are integrated in the housing 8 by molding materials 11 and 12.

  The Barkhausen noise inspection apparatus includes the detection head 1 and the apparatus main body 13. The apparatus body 13 includes the signal processing unit 14 and the display unit 18. In addition to the power supply 15 and the Barkhausen noise detection circuit 16, the signal processing unit 14 includes a signal processing circuit 17 that processes the Barkhausen noise extracted by the detection circuit 16. The power source 15 supplies an alternating current to the exciting coil 2 as described above, but the amplitude, frequency, and waveform of the alternating current can be changed, and a direct current bias current can be superimposed on the alternating current. . The signal processing circuit 17 is a circuit that performs signal processing on the Barkhausen noise extracted by the Barkhausen noise detection circuit 16 in the preceding stage. The effective value, the maximum or average value of the amplitude of the Barkhausen noise signal, the amplitude of the envelope, etc. Is measured and used as the Barkhausen noise value. The Barkhausen noise value may be a value obtained by measuring the value of Barkhausen noise for several cycles of the alternating magnetic field and obtaining an average value thereof. The signal processing circuit 17 determines that there is an abnormality (such as grinding burn) on the surface of the inspection object 20 when the measured Barkhausen noise value exceeds a predetermined threshold value. The display unit 18 displays the Barkhausen noise value measured by the signal processing unit 14 and the presence / absence of an abnormality.

  According to this Barkhausen noise inspection apparatus, since the coatings 7 and 8 are applied to at least the portions of the yokes 4 and 5 that are the magnetic cores of the excitation coil 2 and the detection coil 3 that are in contact with the inspection object 20, the surface of the inspection object 20. Even if the detection head 1 is slid, the surface of the inspection object 20 is not damaged.

As in the embodiment, when an epoxy resin or silicon elastic material softer than the metal material used as the material of the inspection object 20 is used as the material of the coatings 7 and 8, the inspection object due to the sliding of the detection head 1 is used. Scratches on the surface of the object 20 can be more reliably prevented.
In addition, when the material of the coatings 7 and 8 is a non-magnetic base material such as an epoxy resin or a silicon elastic material mixed with magnetic powder, both the scratch prevention effect and the magnetic resistance reduction effect are achieved. Can be made.

FIG. 5 shows an example of a nondestructive inspection performed using the Barkhausen noise inspection apparatus. Here, it is used as a device for detecting the quality of a bearing, which is a kind of rolling device, and specifically detects grinding burn of the rolling surface 21a of the inner ring 21 of the bearing. The detection head 1 of the Barkhausen noise inspection apparatus is supported by a movable support member 22, and detects an abnormal part while sliding on the surface of the rolling surface 21 a of the bearing inner ring 21 by the movement of the support member 22. The bearing inner ring 21 is fitted on the outer diameter surface of the rotating shaft 23. By rotating the rotating shaft 23, the detection head 1 is slid on the entire circumferential surface of the rolling surface 21a of the bearing inner ring 21 and ground. Burns can be inspected.
When the Barkhausen noise inspection apparatus is used on-line in this way, it is possible to inspect all abnormalities such as grinding burn of the rolling surface 21a of the bearing inner ring 21 and improve the quality assurance capability.

  Although FIG. 5 shows an example in which the Barkhausen noise inspection device is used for inspection of grinding burn on the rolling surface 21a of the bearing inner ring 21, surface information to be detected may be residual stress or a defect. Further, the inspection object is not limited to the inner ring 21 that is a bearing component, and may be, for example, one that detects surface information of the bearing itself. Further, the inspection object is not limited to the bearing but may be another rolling device or rolling device part. In this case, the surface information of the rolling device or rolling device component is not damaged. Can be detected.

1 is a schematic configuration diagram of a Barkhausen noise inspection apparatus according to an embodiment of the present invention. (A) is front sectional drawing of the excitation part in the Barkhausen noise inspection apparatus, (B) is the side sectional drawing. (A) is front sectional drawing of the detection part in the Barkhausen noise test | inspection apparatus, (B) is the side view. It is a specific block diagram of the Barkhausen noise inspection apparatus. It is explanatory drawing which shows one usage example of the Barkhausen noise inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Detection head 2 ... Excitation coil 3 ... Detection coil 4 ... Yoke (excitation coil magnetic core)
5 ... Yoke (magnetic core of detection coil)
6, 7 ... Coating 20 ... Inspection object 21 ... Bearing inner ring (Rolling device parts)

Claims (8)

In a Barkhausen noise inspection apparatus including a detection head having an excitation coil for magnetizing an inspection object and a detection coil for detecting Barkhausen noise generated by the magnetized inspection object,
A Barkhausen noise inspection apparatus, wherein a coating is applied to at least a portion of the magnetic core of the excitation coil and the detection coil that is in contact with the inspection object.   The Barkhausen noise inspection apparatus according to claim 1, wherein the coating material is an epoxy resin.   The Barkhausen noise inspection apparatus according to claim 1, wherein the coating material is a silicon-based elastic material.   4. The Barkhausen noise inspection apparatus according to claim 1, wherein the coating material is magnetic.   5. The Barkhausen noise inspection apparatus according to claim 4, wherein the coating material is a non-magnetic base material mixed with magnetic powder.   6. The Barkhausen noise inspection apparatus according to claim 1, wherein the Barkhausen noise inspection apparatus is used for detecting information on a surface of a rolling device or a surface of a rolling device component.   8. The Barkhausen noise inspection apparatus according to claim 6, wherein the detection information is detected by bringing the detection head into sliding contact with a surface of the rolling device or a surface of a rolling device component.   8. The Barkhausen noise inspection apparatus according to claim 6 or 7, wherein the surface information to be detected is surface grinding burn, residual stress, or a defect.

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