JP2010230485A - Barkhausen noise test apparatus and barkhausen noise test method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Barkhausen noise test apparatus capable of detecting Barkhausen noise having a wide frequency band. <P>SOLUTION: The Barkhausen noise test apparatus includes: a detection head 1 having an exciting coil 2 for magnetizing an object under test 40 and a detection sensor 3 for detecting the Barkhausen noise emitted by the magnetized object under test 40; and an AC power supply 12 for supplying AC current which causes the exciting coil 2 to generate an AC magnetic field for above magnetization. A magnetic sensor employing no coil is used as the detection sensor 3 and detects surface fluxes of the object under test 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a Barkhausen noise inspection apparatus and Barkhausen noise inspection method for performing nondestructive inspection using Barkhausen noise.

  In the process of magnetizing a ferromagnetic metal material, Barkhausen noise occurs due to the discontinuity of domain wall movement pinned by non-magnetic materials and internal defects mixed in the metal material. Since the magnitude of this Barkhausen noise has a correlation with the hardness and residual stress of the metal material, it can be used for metal structure estimation by measuring the Barkhausen noise without destroying the test object made of the metal material. Can be obtained.

  As a non-destructive inspection apparatus using the Barkhausen noise, a Barkhausen noise inspection apparatus is known in which a measurer presses a detection head against an object to be inspected (for example, Patent Document 1). 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. In the Barkhausen noise inspection apparatus disclosed in Patent Document 1, the relationship between the magnitude of Barkhausen noise and the hardness of the material is measured in advance for each material of the inspection object, and the magnitude of Barkhausen noise detected. From the above, an abnormal point due to grinding burn on the surface of the inspection object is detected. Since the measurement depth at this time is determined by the frequency of Barkhausen noise to be detected, a detection mechanism capable of detecting Barkhausen noise in a wide frequency band under uniform conditions is required. In addition, the detection information on the inspection object in this case includes residual stress, hardness, load, etc. in addition to grinding burn (for example, Patent Documents 2 to 4).

Japanese Patent Laid-Open No. 02-262958 Japanese Patent No. 2955007 JP 2001-133441 A JP 2006-266686 A

  Although a method using a coil for detecting Barkhausen noise has been proposed (for example, Patent Document 2), the frequency band of Barkhausen noise detected by the resonance frequency of an inductor and a cable is limited. In this case, in order to increase the frequency band of the Barkhausen noise detected by increasing the resonance frequency, it is necessary to reduce the inductance of the detection coil, but this reduces the S / N of the detection signal.

  Barkhausen noise changes due to the residual magnetism of the inspection object. When the object to be inspected is a mechanical part such as a bearing, a magnet chuck or the like is used in the polishing process of the manufacture, and thus magnetism may remain in the mechanical part. In this case, since the value of Barkhausen noise is affected by the residual magnetism of the machine part, the detection accuracy of grinding burn etc. is deteriorated.

An object of the present invention is to provide a Barkhausen noise inspection apparatus capable of detecting Barkhausen noise in a wide frequency band.
Another object of the present invention is to provide a Barkhausen noise inspection apparatus and a Barkhausen noise inspection method capable of accurately detecting Barkhausen noise without being affected by residual magnetism of an inspection object.

A first Barkhausen noise inspection apparatus according to the present invention includes an excitation coil that magnetizes an inspection object, a detection head that includes a detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and the excitation coil In the Barkhausen noise inspection apparatus provided with an AC power source for supplying an AC current for generating an AC magnetic field for magnetization, the detection sensor is a coil non-use type magnetic field sensor, and the surface of the inspection object It is characterized by detecting magnetic flux.
According to this configuration, since the coil non-use type magnetic field sensor is used as the detection sensor for detecting the Barkhausen noise generated by the magnetized inspection object, the influence of the frequency of the Barkhausen noise on the detection signal is small. Therefore, it is possible to detect Barkhausen noise in a wide frequency band from the strength of the surface magnetic flux of the inspection object detected by the magnetic field sensor.

  In the present invention, the magnetic field sensor includes, for example, a Hall sensor, an MR sensor (a sensor using a magnetoresistive effect element), a GMR sensor (a sensor using a giant magnetoresistive effect element), and an MI sensor (a sensor using a magnetoimpedance effect). )

  In the present invention, output signal processing means for extracting Barkhausen noise of a specific frequency from the detection signal of the magnetic field sensor using a bandpass filter may be provided. In the case of this configuration, Barkhausen noise having a frequency optimum for the required detection depth can be detected.

  In the present invention, the output signal processing means may include cut-off frequency changing means for variably setting a cut-off frequency of the bandpass filter. In the case of this configuration, it is possible to detect Barkhausen noise in a wide range of frequencies by variably setting the cutoff frequency of the bandpass filter by the cutoff frequency changing means.

  In the present invention, the AC power supply may include AC current frequency changing means for variably setting the frequency of the AC current supplied to the exciting coil. In this configuration, by changing the frequency of the AC magnetic field that excites the inspection object in accordance with the required detection depth, it is possible to effectively detect Barkhausen noise having a frequency optimum for the detection depth. it can.

In this invention, the pre-magnetization detection magnetic field sensor for detecting the surface magnetic flux of the inspection object before magnetization by the excitation coil, and the bulk detected by the detection sensor based on the surface magnetic flux detected by the pre-magnetization detection magnetic field sensor. Correction means for correcting the Hausen noise may be provided.
In the case of this configuration, when the surface magnetic flux of the inspection object before being magnetized by the exciting coil is detected by the pre-magnetization inspection magnetic field sensor, this can be detected when the inspection object has residual magnetism. . Thereafter, the Barkhausen noise detected by the magnetic field sensor from the magnetized inspection object is corrected by the correcting means based on the detection signal from the pre-magnetization inspection magnetic field sensor. In some cases, the residual magnetism can be prevented from affecting the detection value of Barkhausen noise, and Barkhausen noise can be detected with high accuracy.

  In the present invention, the pre-magnetization detection magnetic field sensor may be capable of detecting a DC magnetic field. In the case of this configuration, it is possible to effectively detect residual magnetism.

  In the present invention, the pre-magnetization detection magnetic field sensor is, for example, any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor.

  In the present invention, the Barkhausen noise detection magnetic field sensor and the pre-magnetization detection magnetic field sensor are shared by one magnetic field sensor, and the output of the one magnetic field sensor is used as a processing circuit for the Barkhausen noise detection signal and the correction unit. A switching circuit for switching to and inputting may be provided. In the case of this configuration, one magnetic field sensor can be shared for Barkhausen noise detection and detection of surface magnetic flux before magnetization, so that the apparatus can be configured compactly.

  In the present invention, the Barkhausen noise inspection apparatus may be provided with grinding burn detection means for detecting grinding burn of a metal product from the Barkhausen noise detected by the detection sensor.

  In the present invention, the Barkhausen noise inspection apparatus may be provided with a residual stress measuring means for detecting the residual stress of the rolling device or rolling device parts from the Barkhausen noise detected by the detection sensor. .

A second Barkhausen noise inspection apparatus according to the present invention includes an excitation coil for magnetizing an inspection object, a detection head having a detection coil for detecting Barkhausen noise generated by the magnetized inspection object, and the excitation coil In a Barkhausen noise inspection apparatus provided with an AC power supply for supplying an AC current for generating an AC magnetic field for magnetization, a magnetic field sensor for detecting a surface magnetic flux of the inspection object before magnetization by the excitation coil, Correction means for correcting the Barkhausen noise detected by the detection coil based on the surface magnetic flux detected by the magnetic field sensor is provided.
According to this configuration, the surface magnetic flux of the inspection object before being magnetized by the exciting coil is detected by the pre-magnetization inspection magnetic field sensor, and the Barkhausen noise detected by the detection coil from the magnetized inspection object is detected for the pre-magnetization inspection. By correcting by the correction means based on the detection signal from the magnetic field sensor, it is possible to eliminate the influence of the residual magnetism of the inspection object on the detection value of the Barkhausen noise, and to detect the Barkhausen noise accurately. Can do.

  In the present invention, the magnetic field sensor may be capable of detecting a DC magnetic field. In the case of this configuration, it is possible to effectively detect residual magnetism.

  In the present invention, the magnetic field sensor is, for example, any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor.

  In the present invention, the Barkhausen noise inspection device may be used for detecting information on a rolling device or rolling device parts. The detection head may detect Barkhausen noise by slidingly contacting the surface of the rolling device or rolling device component.

  In the present invention, the information is, for example, any one of grinding burn, residual stress, and defect of the surface of the rolling device or rolling device component.

A Barkhausen noise inspection method according to the present invention includes a magnetization process in which an inspection object is magnetized by an alternating magnetic field, and a detection process in which Barkhausen noise generated by the inspection object in the magnetization process is detected. Before the magnetization process, a pre-magnetization detection process for detecting the surface magnetic flux of the inspection object, and a correction process for correcting the Barkhausen noise detected in the detection process based on the surface magnetic flux detected in the pre-magnetization detection process It is characterized by having.
According to this Barkhausen noise inspection method, since the Barkhausen noise detected in the detection process is corrected based on the surface magnetic flux detected in the pre-magnetization detection process, the Barkhausen noise is accurately detected without being affected by the residual magnetism of the inspection object. Noise can be detected.

A first Barkhausen noise inspection apparatus according to the present invention includes an excitation coil that magnetizes an inspection object, a detection head that includes a detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and the excitation coil In the Barkhausen noise inspection apparatus provided with an AC power source for supplying an AC current for generating an AC magnetic field for magnetization, the detection sensor is a coil non-use type magnetic field sensor, and the surface of the inspection object Since the magnetic flux is detected, Barkhausen noise in a wide frequency band can be detected.
A first Barkhause noise inspection apparatus according to the present invention includes an excitation coil for magnetizing an inspection object, a detection head having a detection coil for detecting Barkhausen noise generated by the magnetized inspection object, and the excitation coil In a Barkhausen noise inspection apparatus provided with an AC power supply for supplying an AC current for generating an AC magnetic field for magnetization, a magnetic field sensor for detecting a surface magnetic flux of the inspection object before magnetization by the excitation coil, Since the correction means for correcting the Barkhausen noise detected by the detection coil is provided based on the surface magnetic flux detected by the magnetic field sensor, the Barkhausen noise can be accurately detected without being affected by the residual magnetism of the inspection object. Can do.
A Barkhausen noise inspection method according to the present invention includes a magnetization process in which an inspection object is magnetized by an alternating magnetic field, and a detection process for detecting Barkhausen noise generated by the inspection object in the magnetization process. In the method, prior to the magnetization process, a pre-magnetization detection process for detecting the surface magnetic flux of the inspection object, and a correction for correcting the Barkhausen noise detected in the detection process based on the surface magnetic flux detected in the pre-magnetization detection process Therefore, Barkhausen noise can be accurately detected without being affected by the residual magnetism of the inspection object.

1 is a schematic configuration diagram of a Barkhausen noise inspection apparatus according to an embodiment of the present invention. It is a schematic block diagram of the Barkhausen noise inspection apparatus concerning other embodiment of this invention. It is a schematic block diagram of the Barkhausen noise inspection apparatus concerning further another embodiment of this invention. It is a schematic block diagram of the Barkhausen noise inspection apparatus concerning further another embodiment of this invention. It is a schematic block diagram of the detection head in the Barkhausen noise inspection apparatus. It is explanatory drawing which shows one usage example of the Barkhausen noise inspection apparatus.

  A first embodiment of the present invention will be described with reference to FIG. This Barkhausen noise inspection apparatus is an apparatus that performs nondestructive inspection using Barkhausen noise, and includes a detection head 1 including an excitation coil 2 and a magnetic field sensor 3, and a controller 10. At the time of inspection, the detection head 1 is pressed against the surface of the inspection object 40.

  The exciting coil 2 in the detection head 1 is a coil for magnetizing the inspection object 40, and is wound around the iron core 4 serving as a magnetic core. The iron core 4 is made of a magnetic oxide such as ferrite or a laminated silicon steel plate. The magnetization sensor 3 is a coil non-use type sensor for detecting Barkhausen noise generated by the magnetized inspection object 40, and specifically detects the surface magnetic flux of the inspection object 40. As the magnetic field sensor 3, any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor is used. In a state where the detection head 1 is pressed against the surface of the inspection object 40, the iron core 4 serving as the magnetic core of the exciting coil 2 and the magnetic field sensor 3 are pressed against the surface of the inspection object 40. In addition to the excitation coil 2 and the magnetic field sensor 3, the detection head 1 is provided with a magnetic flux detection sensor 5 that detects a magnetic flux that excites the inspection object 40. Here, a magnetic field sensor is used as the magnetic flux detection sensor 5.

  The controller 10 includes a current control unit 11 including an AC power supply 12 that supplies an excitation AC current to the excitation coil 2, and an output signal processing unit 15 that is a means for processing an output signal of the magnetic field sensor 3. The current control unit 11 controls the alternating current of the alternating current power supply 12 based on the strength of the magnetic flux detected by the magnetic flux detection sensor 5 to maintain a constant magnetic flux for exciting the inspection object 40, and an alternating current power supply And AC current frequency changing means 14 for variably setting the frequency of the AC current supplied from 12 to the exciting coil 2.

  The output signal processing unit 15 includes a Barkhausen noise detection circuit 16 and property detection means 17. The Barkhausen noise detection circuit 16 is a circuit that extracts Barkhausen noise from the detection signal of the magnetic field sensor 3. The sensor circuit 18 includes an amplifier that amplifies the detection signal of the magnetic field sensor 3 and the sensor circuit 18. A band-pass filter 19 that extracts Barkhausen noise of a specific frequency from the detection signal, and a cut-off frequency changing unit 20 that variably sets the cut-off frequency of the band-pass filter 19 are provided. The bandpass filter 19 calculates a Barkhausen noise value to be actually used from the effective value, maximum value or average value of amplitude, amplitude of envelope, and the like of the extracted Barkhausen noise signal. 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 property detection means 17 is a means for detecting the property for detection of the inspection object 40 from the Barkhausen noise extracted by the Barkhausen noise detection circuit 16. The property for detection may be a property that can be detected from Barkhausen noise, but here it is grinding burn and residual stress. The grinding burn and residual stress are detected by the grinding burn detection means 21 and the residual stress measurement means 22 constituting the property detection means 17, respectively.

  Next, the operation of the Barkhausen noise inspection apparatus will be described. When the detection head 1 is pressed against the inspection object 40, the iron core 4 and the magnetic field sensor 3 that are the magnetic cores of the excitation coil 2 come into contact with the inspection object 40, and the iron core 4 and the inspection object 40 constitute a magnetic closed circuit. The The exciting coil 2 is supplied with an alternating current from the alternating current power source 12 to generate an alternating magnetic field, whereby the inspection object 40 is magnetized. The magnetic field sensor 3 detects the surface magnetic flux of the magnetized inspection object 40. The Barkhausen noise detection circuit 16 of the output signal processing unit 15 to which the detection signal of the magnetic field sensor 3 is input extracts Barkhausen noise of a predetermined frequency from the detection signal. Further, the property detection means 17 detects grinding burn and residual stress in the inspection object 40 from the extracted Barkhausen noise.

  According to the Barkhausen noise inspection apparatus having this configuration, the coil non-use type magnetic field sensor 3 is used as the detection sensor for detecting the Barkhausen noise generated by the magnetized inspection object 40, and therefore, a detection signal based on the frequency of the Barkhausen noise. There is little influence on. Therefore, it is possible to detect Barkhausen noise in a wide frequency band from the strength of the surface magnetic flux of the inspection object 40 detected by the magnetic field sensor 3.

  The measurement depth of Barkhausen noise is determined by the frequency band of Barkhausen noise. That is, the higher the Barkhausen noise frequency band, the smaller the measured depth of Barkhausen noise. In this embodiment, since the Barkhausen noise detection circuit 16 of the output signal processing unit 15 uses the bandpass filter 19 to extract Barkhausen noise of a specific frequency from the detection signal of the magnetic field sensor 3, In the band pass filter 19, by setting a cutoff frequency corresponding to the required measurement depth in the inspection object 40, it is possible to detect Barkhausen noise having the required depth.

  In this embodiment, since the cutoff frequency changing means 20 for variably setting the cutoff frequency of the bandpass filter 19 is provided, the cutoff frequency of the bandpass filter 19 is variably set by the cutoff frequency changing means 20. By doing so, it is possible to detect Barkhausen noise of a wide range of frequencies.

  In this embodiment, the AC power supply 12 in the current control unit 11 is provided with AC current frequency changing means 14 for variably setting the frequency of the AC current supplied to the exciting coil 2, so that the required measurement depth can be obtained. Accordingly, by changing the frequency of the alternating magnetic field that excites the inspection object 40, it is possible to effectively detect Barkhausen noise having a frequency that is optimal for the measurement depth.

  FIG. 2 shows another embodiment of the present invention. In the Barkhausen noise inspection apparatus, in the embodiment of FIG. 1, a pre-magnetization detection magnetic field sensor 3A for detecting the surface magnetic flux of the inspection object 40 before magnetization by the exciting coil 2 is added to the detection head 1, and the controller 10 The output signal processing unit 15 is provided with correction means 24 for correcting the Barkhausen noise extracted by the Barkhausen noise detection circuit 16 based on the surface magnetic flux detected by the pre-magnetization detection magnetic field sensor 3A. The pre-magnetization detection magnetic field sensor 3A is a sensor capable of measuring a DC magnetic field, and any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor is used. The detection signal of the pre-magnetization detection magnetic field sensor 3A is processed by a sensor circuit 23 including an amplifier and the like, and then input to the correction means 24. Other configurations are the same as those in the embodiment of FIG.

In this embodiment, the surface magnetic flux of the inspection object 40 before being magnetized by the exciting coil 2 is detected by the pre-magnetization inspection magnetic field sensor 3 </ b> A, so that it is detected when the inspection object 40 has residual magnetism. can do. Here, since a sensor capable of measuring a DC magnetic field is used as the pre-magnetization inspection magnetic field sensor 3A, the residual magnetism can be detected effectively.
Thereafter, the Barkhausen noise detected by the magnetic field sensor 3 from the magnetized inspection object 40 is corrected by the correcting means 24 based on the detection signal from the pre-magnetization inspection magnetic field sensor 3A. If there is, it is possible to eliminate the influence of the residual magnetism on the detection value of Barkhausen noise, and it is possible to improve the detection accuracy of the grinding burn of the inspection object 40 and the residual stress.

  FIG. 3 shows still another embodiment of the present invention. In the Barkhausen noise inspection apparatus, in the embodiment of FIG. 2, the magnetic field sensor 3A for pre-magnetization detection is omitted, and the magnetic field sensor 3 for detecting Barkhausen noise is shared for pre-magnetization detection. The output signal processing unit 15 is provided with a switching circuit 25 that inputs the detection signal before the magnetization from the sensor circuit 23 to the correction means 24 and switches to the Barkhausen noise detection circuit 16 when Barkhausen noise is detected. Other configurations are the same as those in the embodiment of FIG.

  Thus, in this embodiment, since one magnetic field sensor 3 is shared for Barkhausen noise detection and pre-magnetization detection, the apparatus can be configured compactly.

  4 and 5 show still another embodiment of the present invention. In this embodiment, components having the same functions as those in the embodiment of FIGS. 1 to 3 are denoted by the same reference numerals as in FIGS. As shown in FIG. 4, the Barkhausen noise inspection apparatus includes a detection head 1 having an excitation coil 2, a detection coil 6, and a pre-magnetization detection magnetic field sensor 3 </ b> A, and an apparatus body 9. The detection coil 6 serves as a detection sensor that detects Barkhausen noise generated by the magnetized inspection object 40 in place of the magnetic field sensor 3 in the embodiment of FIGS. As shown in FIGS. 4 and 5, the detection head 1 includes an iron core 4 in which an excitation coil 2 is wound in a cylindrical housing 7, an iron core 8 in which a detection coil 6 is wound, and a pre-magnetization detection magnetic field sensor 3A. Is configured. The iron cores 4 and 8 are made of a magnetic oxide such as ferrite or a laminated silicon steel plate. The exciting coil 2 is wound around the iron core 4 via the winding frame 29, and the detection coil 6 is wound around the iron core 8 via the winding frame 30. The detection coil 6 may be an air core coil that does not have the iron core 8. The excitation coil 2 and the detection coil 6 are integrated in the housing 7 by molding materials 31 and 32.

  The apparatus main body 9 includes a controller 10 and a display unit 33. In addition to the AC power supply 12 and the Barkhausen noise detection circuit 16, the controller 10 includes a signal processing circuit 27 that processes the Barkhausen noise extracted by the detection circuit 16. The AC power supply 12 supplies an AC current to the exciting coil 2 as described above, but can change the amplitude, frequency, and waveform of the AC current, and a DC bias can be superimposed on the AC current. . The signal processing circuit 27 is a circuit that processes the Barkhausen noise extracted by the Barkhausen noise detection circuit 16 and measures the effective value, maximum value, average value, envelope amplitude, etc. of the Barkhausen noise signal. This is 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.

  Based on the detection signal of the pre-magnetization detection magnetic field sensor 3A, the signal processing circuit 27 corrects the Barkhausen noise extracted by the Barkhausen noise detection circuit 16, and checks the obtained Barkhausen noise value. And a property detection means 17 for detecting the property of the object 40. The signal processing circuit 27 calculates the Barkhausen noise value that is actually used from the maximum amplitude value, the effective value, the average value, the envelope amplitude, etc. of the Barkhausen noise extracted by the Barkhausen noise detection circuit 16. The detection signal of the pre-magnetization detection magnetic field sensor 3A is processed by a sensor circuit 23 having an amplifier or the like and input to the correction means 24. The property detection unit 17 includes a grinding burn detection unit 21 that detects grinding burn, a residual stress measurement unit 22 that detects residual stress, and a defect detection unit 26 that detects defects. These grinding burn detection means 21, residual stress measurement means 22, and defect detection means 26 determine that there is an abnormality such as grinding burn when the obtained Barkhausen noise value exceeds a predetermined threshold value. To do. The display unit 33 displays the Barkhausen noise value obtained by the signal processing circuit 27, the presence / absence of abnormality such as grinding burn, the measured value of residual stress, and the like. As a residual stress measurement method, the residual stress is obtained from a calibration curve obtained by measuring the stress and Barkhausen noise value in advance. The signal processing circuit 27 determines the residual stress by setting the calibration curve, for example, and applying the Barkhausen noise value to the calibration curve.

  Barkhausen noise detection using the Barkhausen noise inspection apparatus of this embodiment is performed according to the following procedure. When the detection head 1 is pressed against the inspection object 40, the iron core 4 that is the magnetic core of the excitation coil 2 and the pre-magnetization detection magnetic field sensor 3 A come into contact with the inspection object 40, and the iron core 4 and the inspection object 40 are magnetically closed. A circuit is constructed. The exciting coil 2 is supplied with an alternating current from the alternating current power source 12 to generate an alternating magnetic field, whereby the inspection object 40 is magnetized. Prior to the magnetization by the exciting coil 2, the surface magnetic flux of the inspection object 40 is detected by the pre-magnetization detection magnetic field sensor 3A. Thereby, when the inspection object 40 has residual magnetism, the residual magnetism can be detected. Thereafter, the surface coil of the magnetized inspection object 40 is detected by the detection coil 6 by the exciting coil 2. The detection signal of the detection coil 6 is input to the Barkhausen noise detection circuit 16 of the output signal processing unit 15 as in the case of the detection signal of the magnetic field sensor 3 in the embodiment of FIGS. Barkhausen noise is extracted and input to the signal processing circuit 27. The signal processing circuit 27 first calculates a Barkhausen noise value to be actually used from the extracted Barkhausen noise signal. Next, the Barkhausen noise value is corrected by the correcting means 24 based on the detection signal of the pre-magnetization detection magnetic field sensor 3A. The property detection means 17 of the signal processing circuit 27 detects grinding burn, residual stress, and defects based on the Barkhausen noise value corrected as described above. As a correction method, a correction table is created by measuring the relationship between residual magnetism and Barkhausen noise value, and correction is performed with reference to the correction table. That is, for example, an operator measures the relationship between the residual magnetism and the Barkhausen noise value, and creates a correction table. The created correction table is stored in a storage unit (not shown) provided in the output signal processing unit 15. The correction unit 24 reads the correction table stored in the storage unit, and collates the Barkhausen noise value with the correction table, thereby correcting the detection result such as grinding burn with high accuracy.

  In this way, the surface magnetic flux of the inspection object 40 before being magnetized by the excitation coil 2 is detected by the pre-magnetization inspection magnetic field sensor 3A, and the Barkhausen noise detected by the detection coil 6 from the magnetized inspection object 40 is By correcting by the correcting means 24 based on the detection signal from the pre-magnetization inspection magnetic field sensor 3A, it is possible to eliminate the influence of the residual magnetism of the inspection object 40 on the detected value of Barkhausen noise. The detection accuracy of grinding burn, residual stress, and defects of the object 40 can be increased.

FIG. 6 shows an example of a destructive inspection performed using the Barkhausen noise inspection apparatus. Here, grinding burn of the rolling surface 41a of the inner ring 41 of the bearing is detected. The detection head 1 of the Barkhausen noise inspection apparatus is supported by a movable support member 42 and is brought into contact with the rolling surface 41a of the bearing inner ring 41 in a vertical posture, and the surface of the rolling surface 41a is moved by the movement of the support member 42. Detect abnormal parts while sliding. The bearing inner ring 1 is fitted on the outer diameter surface of the rotating shaft 43. By rotating the rotating shaft 43, the detection head 1 is slid on the entire circumferential surface of the rolling surface 41a of the bearing inner ring 41 and ground. Burns can be inspected.
When the Barkhausen noise inspection device is used on the production line of the bearing inner ring 4 as described above, the grinding burn of the rolling contact surface 41a of the bearing inner ring 41 can be accurately inspected, and the quality assurance capability can be enhanced. .

  Although FIG. 6 shows an example in which the Barkhausen noise inspection device is used for inspection of grinding burn on the rolling surface 41a of the bearing inner ring 41, surface information to be detected may be residual stress or a defect. Further, the inspection object is not limited to the inner ring 41 that is a bearing component, and may be, for example, a device that detects surface information of the bearing itself. Further, the inspection object is not limited to the bearing, and may be another rolling device or rolling device component. In this case, the surface information of the rolling device or rolling device component can be detected with high accuracy. it can.

DESCRIPTION OF SYMBOLS 1 ... Detection head 2 ... Excitation coil 3 ... Magnetic field sensor 3A ... Pre-magnetization detection magnetic field sensor 6 ... Detection coil 12 ... AC power supply 14 ... AC current frequency change means 15 ... Output signal processing part 16 ... Barkhausen noise detection circuit 17 ... Property detecting means 19 ... band pass filter 20 ... cut-off frequency changing means 21 ... grinding burn detecting means 22 ... residual stress measuring means 24 ... correcting means 25 ... switching circuit 26 ... defect detecting means 40 ... inspection object

Claims (18)

An excitation coil that magnetizes the inspection object, a detection head having a detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and an alternating current that generates an alternating magnetic field for magnetization is supplied to the excitation coil In Barkhausen noise inspection equipment with AC power supply
The Barkhausen noise inspection apparatus, wherein the detection sensor is a coil non-use type magnetic field sensor and detects a surface magnetic flux of the inspection object.   2. The Barkhausen noise inspection apparatus according to claim 1, wherein the magnetic field sensor is any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor.   3. The Barkhausen noise inspection apparatus according to claim 1, further comprising output signal processing means for extracting Barkhausen noise of a specific frequency from a detection signal of the magnetic field sensor using a bandpass filter.   4. The Barkhausen noise inspection apparatus according to claim 3, wherein the output signal processing means includes cut-off frequency changing means for variably setting a cut-off frequency of the bandpass filter.   5. The Barkhausen noise inspection apparatus according to claim 1, wherein the AC power source includes AC current frequency changing means that variably sets a frequency of an AC current supplied to the exciting coil. 6.   6. The pre-magnetization detection magnetic field sensor for detecting a surface magnetic flux of the inspection object before magnetization by the exciting coil according to claim 1, and a surface detected by the pre-magnetization detection magnetic field sensor. A Barkhausen noise inspection apparatus provided with correction means for correcting Barkhausen noise detected by the detection sensor based on magnetic flux.   7. The Barkhausen noise inspection apparatus according to claim 6, wherein the pre-magnetization detection magnetic field sensor is capable of detecting a DC magnetic field.   8. The Barkhausen noise inspection apparatus according to claim 6, wherein the pre-magnetization detection magnetic field sensor is any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor.   9. The magnetic field sensor for Barkhausen noise detection and the magnetic field sensor for pre-magnetization detection are shared by one magnetic field sensor according to claim 6, and the output of the one magnetic field sensor is detected by Barkhausen noise. Barkhausen noise inspection apparatus provided with a switching circuit for switching between the signal processing circuit and the correction means for input.   10. The Barkhausen noise inspection apparatus according to claim 1, further comprising a grinding burn detection unit configured to detect grinding burn of a metal product from the Barkhausen noise detected by the detection sensor. 11.   10. The Barkhausen noise test according to claim 1, further comprising a residual stress measuring unit that detects a residual stress of a rolling device or a rolling device component from the Barkhausen noise detected by the detection sensor. apparatus. An excitation coil that magnetizes the inspection object, a detection head having a detection coil that detects Barkhausen noise generated by the magnetized inspection object, and an alternating current that generates an alternating magnetic field for magnetization is supplied to the excitation coil In Barkhausen noise inspection equipment with AC power supply
A magnetic field sensor for detecting the surface magnetic flux of the inspection object before magnetization by the excitation coil, and a correcting means for correcting the Barkhausen noise detected by the detection coil based on the surface magnetic flux detected by the magnetic field sensor are provided. Barkhausen noise inspection device characterized by that.   13. The Barkhausen noise inspection apparatus according to claim 12, wherein the magnetic field sensor is capable of detecting a DC magnetic field.   14. The Barkhausen noise inspection apparatus according to claim 12, wherein the magnetic field sensor is any one of a Hall sensor, an MR sensor, a GMR sensor, and an MI sensor.   15. The Barkhausen noise inspection device according to any one of claims 12 to 14, which is used for detecting information on a rolling device or rolling device parts.   16. The Barkhausen noise inspection apparatus according to claim 15, wherein the detection head detects Barkhausen noise by slidingly contacting a surface of a rolling device or a rolling device component.   The Barkhausen noise inspection device according to claim 15 or 16, wherein the information is any one of grinding burn, residual stress, and defect of a surface of a rolling device or a rolling device component. In a Barkhausen noise inspection method comprising a magnetization process for magnetizing an inspection object by an alternating magnetic field, and a detection process for detecting Barkhausen noise generated by the inspection object in the magnetization process,
Prior to the magnetization process, a pre-magnetization detection process for detecting the surface magnetic flux of the inspection object, and a correction process for correcting the Barkhausen noise detected in the detection process based on the surface magnetic flux detected in the pre-magnetization detection process. Barkhausen noise inspection method characterized by including.

Images