JP2010243174A - Barkhausen noise inspecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Barkhausen noise inspecting device for performing accurate inspection without being affected by displacement of a noise detection sensor for detecting Barkhausen noise or an inspecting object. <P>SOLUTION: The Barkhausen noise inspection device includes an exciting coil 2 for magnetizing the inspecting object 30, the noise detection sensor 3 for detecting the Barkhausen noise issued by the magnetized inspecting object 30, and a power source 12 for supplying alternating current for generating an alternating-current magnetic field for magnetization in the exciting coil 2. The gap between the noise detection sensor 3 and the inspecting object 30 is adjusted to a fixed value by a gap-adjusting means 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a Barkhausen noise inspection apparatus that performs 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. In this case, if the inspection object is a mass-produced product, it is necessary to measure the detection head in a non-contact manner with respect to the inspection object so that problems such as wear do not occur in the 100% inspection.

Japanese Patent Laid-Open No. 02-262958

  However, as described above, when the inspection head is inspected against the inspection object in a non-contact state, if the gap between the inspection object and the detection head changes, the magnitude of Barkhausen noise also changes. Causes detection.

  An object of the present invention is to provide a noise detection sensor for detecting Barkhausen noise and a Barkhausen noise inspection apparatus capable of performing high-accuracy inspection without being affected by the displacement of an inspection object.

The Barkhausen noise inspection apparatus according to the present invention includes an excitation coil that magnetizes an inspection object, a noise detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and an alternating magnetic field for magnetization in the excitation coil. In a Barkhausen noise inspection apparatus provided with a power source for supplying an alternating current that generates a gap, a gap adjusting means for adjusting a gap between the noise detection sensor and the inspection object to a constant value is provided. .
According to this configuration, the Barkhausen noise can be detected by the noise detection sensor in a state where the gap between the noise detection sensor and the inspection object is maintained at a constant value by the gap adjusting means. Therefore, the inspection conditions are made uniform, and it is possible to eliminate the influence of the displacement of the inspection object and the noise detection sensor on the detected Barkhausen noise, thereby improving the detection accuracy. In addition, since the noise detection sensor is not in contact with the inspection object, the problem of wear does not occur, and the entire inspection can be efficiently performed during the production process of the inspection object.

  In the present invention, the gap adjusting means includes a gap sensor that detects a gap between the noise detection sensor and the inspection object, a position adjustment mechanism that adjusts a relative position between the inspection object and the detection coil, A position control device that controls the position adjustment mechanism so that the output of the gap sensor is constant may be provided. Thus, by controlling with the output of a gap sensor, the gap between a noise detection sensor and the said test object can be accurately maintained at a constant value.

In this invention, the gap adjusting means includes a position adjusting mechanism that adjusts a relative position between the inspection object and the detection coil, and a position control device that controls the position adjusting mechanism using an output of the noise detection sensor as a feedback signal; It is good also as what has.
The output of the noise detection sensor is a signal including leakage magnetic flux and Barkhausen noise on the surface of the inspection object, but the magnitude of Barkhausen noise in the output is very small compared to the leakage magnetic flux. Therefore, the output can be regarded as a detected value of leakage magnetic flux by the noise detection sensor. In addition, since the magnitude of the leakage magnetic flux detected by the noise detection sensor is a value reflecting the gap between the noise detection sensor and the inspection object, the output of the noise detection sensor should be input as a feedback signal to the position control device. Is equivalent to the case where the detection signal of the gap sensor is input as a feedback signal. As a result, high-precision inspection can be performed without being affected by the displacement of the noise detection sensor or the inspection object. Further, since the gap sensor can be omitted, the apparatus can be configured at low cost.

  In this invention, the excitation coil and the noise detection sensor are integrally provided in one detection head, and the gap adjusting means adjusts a gap between the noise detection sensor and the inspection object, and at the same time, the excitation The gap between the coil and the inspection object may be adjusted. In the case of this configuration, it is effective in keeping the magnetic flux exciting the inspection object constant, the inspection conditions are made more uniform, and the detection accuracy can be further improved.

  In the present invention, the excitation coil and the noise detection sensor may be provided separately from each other, and the gap adjusting unit may adjust only the gap between the noise detection sensor and the inspection object.

  In the present invention, the noise detection sensor may be a detection coil or a magnetic sensor.

In the present invention, the Barkhausen noise inspection apparatus may include grinding burn detection means for detecting grinding burn of the inspection object from the Barkhausen noise detected by the noise detection sensor.
In the present invention, the Barkhausen noise inspection apparatus may include a residual stress detection unit that detects residual stress on the surface of the inspection object from the Barkhausen noise detected by the noise detection sensor.

  In this invention, the inspection object may be a rolling device or a rolling device part. For example, the signal processing means may detect detection of residual stress on the surface of the rolling device or rolling device component or grinding burn. The rolling device is a device in which rolling elements such as balls and rollers are interposed between components, and includes a rolling bearing, a ball screw, a ball joint, and the like. The rolling device component is a component that constitutes the rolling device, such as a component having a raceway surface with which the rolling element contacts or a rolling element.

  The Barkhausen noise inspection apparatus according to the present invention includes an excitation coil that magnetizes an inspection object, a noise detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and an alternating magnetic field for magnetization in the excitation coil. In a Barkhausen noise inspection apparatus comprising a power supply for supplying an alternating current that generates a noise, since a gap adjusting means for adjusting a gap between the noise detection sensor and the inspection object to a constant value is provided, Barkhausen noise is detected. High-precision inspection is possible without being affected by the displacement of the noise detection sensor or 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 explanatory drawing which shows one usage example of the Barkhausen noise inspection apparatus.

  An 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 an excitation coil 2, a detection coil 3, a controller 10, and a gap adjusting means 20. The excitation coil 2 and the detection coil 3 are integrally provided in one detection head 1. The detection head 1 is configured such that components such as the coils 2 and 3 are accommodated in a case (not shown) made of resin or the like.

  The exciting coil 2 is a coil for magnetizing the inspection object 30 and is wound around an iron core 4 serving as a magnetic core. The detection coil 3 is a coil serving as a noise detection sensor for detecting Barkhausen noise generated by the magnetized inspection object 30 and is wound around an iron core 5 serving as a magnetic core. Specifically, the detection coil 3 detects the surface magnetic flux of the inspection object 30. Each of the iron cores 4 and 5 is made of a magnetic oxide such as ferrite or a laminated silicon steel plate. At the time of inspection, the detection head 1 is brought into a non-contact state with respect to the inspection object 30 from the viewpoint of wear or the like.

  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 processes an output signal of the detection coil 3. In addition to the AC power supply 12, the current control unit 11 controls the AC current of the AC power supply 12 based on the strength of the magnetic flux detected by the detection coil 3 to keep the magnetic flux exciting the inspection object 30 constant. A control device 13 is included.

  The output signal processing unit 15 includes a sensor circuit 16 including an amplifier that amplifies the detection signal of the detection coil 3, and Barkhausen noise extraction for extracting Barkhausen noise of a specific frequency from the detection signal processed by the sensor circuit 16. And a filter 17. The next stage of the output signal processing unit 15 is provided with property detection means 41 for detecting the property of the detection object 30 for detection from the extracted Barkhausen noise. The property for detection purpose is, for example, grinding burn or residual stress generated on the surface of the inspection object 30 at the time of grinding or cutting, and a grinding burn detection unit 42 or a residual stress detection unit 43 is provided as the property detection unit 41. It is done. These grinding burn detection means 42 and residual stress detection means 43 detect the magnitude of Barkhausen noise or the like extracted by the output signal processing unit 15 with the set value to detect the presence or absence of grinding burn, and exceed a predetermined value. It is possible to determine the presence or absence of residual stress, or to measure the depth and range of grinding burn and the magnitude of residual stress.

  The gap adjusting means 20 is a means for adjusting the gap between the detection coil 3 and the inspection object 30 to a constant value during inspection. The gap adjusting means 20 includes a gap sensor 21 that detects a gap between the detection coil 3 and the inspection object 30, a position adjustment mechanism 22 that adjusts a relative position between the detection coil 3 and the inspection object 30, and the gap sensor. The position control device 23 controls the position adjusting mechanism 22 so that the output of 21 is constant.

  The position adjusting mechanism 22 is, for example, a mechanism that supports the detection head 1 and moves it up and down, such as a motor (not shown) that is a lifting drive source and a ball screw that converts the rotation of the motor into a lifting operation of the detection head 1. With a rotation / linear motion conversion mechanism.

  As the gap sensor 21, a capacitance sensor, an eddy current sensor, a reluctance detection type sensor, or the like is used. In this case, the gap between the detection coil 3 and the inspection object 30 is a gap between one end of the iron core 5 around which the detection coil 3 is wound and the surface of the inspection object 30 facing this. The gap sensor 21 is provided integrally with the detection head 1 together with the excitation coil 2 and the detection coil 3. The iron core 4 of the exciting coil 2 is U-shaped, and a detection surface in which both ends of the iron core 4 and one end of the iron core 5 of the detection coil 3 are flat surfaces facing the surface of the inspection object 30 in the detection head 1. The iron cores 4 and 5 of the excitation coil 2 and the detection head 3 are disposed in the detection head 1 so as to be located on the same plane as the first and second detection coils. Thereby, when the gap between the detection coil 3 and the inspection object 30 is adjusted to a constant value, the gap between the excitation coil 2 and the inspection object 30 is also adjusted to the same value. The gap sensor 21 is also arranged in the detection head 1 so as to be flush with the detection surface of the detection head 1.

  Next, the operation of the Barkhausen noise inspection apparatus will be described. The detection head 1 is disposed via the position adjustment mechanism 22 of the gap adjustment means 20 so that the detection surface thereof faces the surface of the inspection object 30. In this arrangement state, the gap sensor 21 detects a gap between the detection coil 3 and the inspection object 30. The position control device 23 receives the output of the gap sensor 21 as a feedback signal, and controls the position adjusting mechanism 22 so that the output becomes constant. Thereby, the gap between the detection coil 3 and the inspection object 30 is kept at a constant value. As described above, both ends of the iron core 4 of the exciting coil 2 are flush with the detection surface of the detection head 2, and one end of the iron core 5 of the detection coil 3 is flush with the detection surface of the detection head 2. Since the gap between the detection coil 3 and the inspection object 30 is maintained at a constant value, the gap between the excitation coil 2 and the inspection object 30 is also maintained at a constant value at the same time. It is.

  On the other hand, a magnetic closed circuit is formed between the iron core 3 of the exciting coil 2 and the inspection object 30 through the gap. 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 30 is magnetized. The detection coil 3 detects the surface magnetic flux of the magnetized inspection object 30. The output signal processing unit 15 to which the detection signal of the detection coil 3 is input extracts Barkhausen noise having a predetermined frequency from the detection signal. Further, the property detection means 41 (not shown) in the next stage detects the grinding burn and residual stress in the detection object 30 by the detection burn detection means 42 and the residual stress detection means 43 from the extracted Barkhausen noise.

  According to the Barkhausen noise inspection apparatus having this configuration, Barkhausen noise is extracted from the detection signal of the detection coil 3 in a state where the gap between the detection coil 3 and the inspection object 30 is maintained at a constant value by the gap adjusting unit 20. As a result, the inspection conditions are made uniform, the influence of the displacement of the inspection object 30 and the detection coil 3 on the extracted Barkhausen noise can be eliminated, and the detection accuracy can be improved.

  In this embodiment, the gap adjusting means 20 adjusts the gap between the detection coil 3 and the inspection object 30 and at the same time adjusts the gap between the excitation coil 2 and the inspection object 30. The inspection is performed with the gap between the inspection object 30 and the inspection object 30 maintained at a constant value, which is effective in keeping the magnetic flux that excites the inspection object 30 constant. The accuracy can be further improved.

  FIG. 2 shows another embodiment of the present invention. In the embodiment shown in FIG. 1, this Barkhausen noise inspection apparatus omits the dedicated gap sensor 21 and feeds back the output of the sensor circuit 16 in the output signal processing unit 15 to the position control device 23 in the gap adjusting means 20. It is used as a signal. That is, the sensor circuit 16 is also used as a gap detection unit. The output before being input to the Barkhausen noise extraction filter 17 in the output signal processing unit 15 is a signal including leakage magnetic flux on the surface of the inspection object 30 and Barkhausen noise. In this case, since the magnitude of the Barkhausen noise in the output is very small as compared with the leakage magnetic flux, the output can be regarded as a detection value of the leakage magnetic flux by the detection coil 3. Further, since the magnitude of the leakage magnetic flux detected by the detection coil 3 is a value reflecting the gap between the detection coil 3 and the inspection object 30, the output of the sensor circuit 16 is sent to the position controller 23 as a feedback signal. The input is equivalent to the case where the detection signal of the gap sensor 21 in the embodiment of FIG. 1 is input as a feedback signal.

  Thus, as in the case of the embodiment of FIG. 1, the detection is performed in a state where the gap between the detection coil 3 and the inspection object 30 and the gap between the excitation coil 2 and the inspection object 30 are kept constant. Since the Barkhausen noise can be extracted from the detection signal of the coil 3, the inspection conditions can be made uniform, and the extracted Barkhausen noise can be prevented from being affected by the displacement of the inspection object 30 and the detection coil 3, Detection accuracy can be improved. Moreover, since the gap sensor 21 can be omitted, the apparatus can be configured at low cost. Other effects are the same as those of the embodiment of FIG. In addition, although the same embodiment and each embodiment after FIG. 3 are provided with the property detection means 41 of FIG. 1, the illustration is abbreviate | omitted.

  FIG. 3 shows still another embodiment of the present invention. In this Barkhausen noise inspection apparatus, in the embodiment shown in FIG. 2, a magnetic sensor 6 is used as a noise detection sensor instead of the detection coil 3 wound around the iron core 5. As the magnetic sensor 6, for example, a Hall sensor, MR sensor, GMR sensor, MI sensor, or the like is used. In this case, the magnetic sensor 6 is disposed in the detection head 1 so that its detection surface is flush with the detection surface of the detection head 1. Other configurations and operational effects are the same as those of the embodiment of FIG.

  FIG. 4 shows still another embodiment of the present invention. In this Barkhausen noise inspection apparatus, in the embodiment shown in FIG. 2, the detection head 1 is omitted and the excitation coil 2 and the detection coil 3 are provided separately. The inspection object 30 is disposed at a position sandwiched between both end portions 4 a and 4 a of the U-shaped iron core 4 that is the magnetic core of the exciting coil 2. Thereby, the whole inspection object 30 is magnetized by the alternating magnetic field generated by the exciting coil 2. The gap adjusting means 20 adjusts only the gap between the detection coil 3 and the inspection object 30. That is, the detection coil 3 is disposed to face the inspection object 30 via the position adjustment mechanism 22 of the gap adjustment means 20. Other configurations and operational effects are the same as those of the embodiment of FIG.

FIG. 5 shows an example of a nondestructive inspection performed using the Barkhausen noise inspection apparatus shown in FIGS. Here, grinding burn of the rolling surface 31a of the inner ring 31 of the bearing is detected. The detection head 1 of the Barkhausen noise inspection apparatus is supported by the head support portion 32 of the position adjustment mechanism 22 in the gap adjustment means 20 and is disposed to face the rolling surface 31a of the bearing inner ring 31 in a vertical posture. An abnormal location is detected while moving along the surface of the rolling surface 31a by the movement. The bearing inner ring 31 is fitted on the outer diameter surface of the rotating shaft 33, and the detecting head 1 is moved along the entire circumferential surface of the rolling surface 31 a of the bearing inner ring 31 by rotating the rotating shaft 33. Grinding burn can be inspected.
If the Barkhausen noise inspection device is used in this way on the production line for rolling device parts such as the bearing inner ring 31, etc., it is possible to accurately inspect all grinding burns of the rolling surface 31a of the bearing inner ring 31 for quality assurance. Ability can be increased.

  Although FIG. 5 shows an example in which the Barkhausen noise inspection device is used for inspection of grinding burn on the rolling surface 31a of the bearing inner ring 31, surface information to be detected may be residual stress or a defect. Further, the inspection object is not limited to the inner ring 31 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, 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 ... Detection coil (noise detection sensor)
6. Magnetic sensor (noise detection sensor)
DESCRIPTION OF SYMBOLS 12 ... AC power supply 20 ... Gap adjustment means 21 ... Gap sensor 22 ... Position adjustment mechanism 23 ... Control apparatus 30 ... Inspection object 31 ... Bearing inner ring

Claims (10)

An excitation coil that magnetizes the inspection object, a noise detection sensor that detects Barkhausen noise generated by the magnetized inspection object, and a power source that supplies an alternating current that generates an alternating magnetic field for magnetization in the excitation coil In Barkhausen noise inspection equipment with
A Barkhausen noise inspection apparatus provided with gap adjustment means for adjusting a gap between the noise detection sensor and the inspection object to a constant value.   The gap adjusting means according to claim 1, wherein the gap adjusting means detects a gap between the noise detection sensor and the inspection object, a position adjustment mechanism that adjusts a relative position between the inspection object and the detection coil, A Kuhausen noise inspection apparatus comprising: a position control device that controls the position adjustment mechanism so that an output of the gap sensor is constant. 2. The position adjustment device according to claim 1, wherein the gap adjustment means controls a position adjustment mechanism that adjusts a relative position between the inspection object and the detection coil, and controls the position adjustment mechanism using an output of the noise detection sensor as a feedback signal. Barkhausen noise inspection device.
  4. The excitation coil and the noise detection sensor according to claim 1, wherein the excitation coil and the noise detection sensor are integrally provided in one detection head, and the gap adjustment unit includes the noise detection sensor and the inspection object. Barkhausen noise inspection apparatus that adjusts the gap between the exciting coil and the inspection object at the same time as adjusting the gap between the excitation coil and the inspection object.   4. The excitation coil and the noise detection sensor according to claim 1, wherein the excitation coil and the noise detection sensor are provided separately from each other, and the gap adjusting unit is configured to provide only a gap between the noise detection sensor and the inspection object. Barkhausen noise inspection system for adjusting   The Barkhausen noise inspection apparatus according to any one of claims 1 to 5, wherein the noise detection sensor is a detection coil.   The Barkhausen noise inspection apparatus according to any one of claims 1 to 5, wherein the noise detection sensor is a magnetic sensor.   8. The Barkhausen noise inspection apparatus according to claim 1, further comprising a grinding burn detection unit configured to detect grinding burn of the inspection object from the Barkhausen noise detected by the noise detection sensor. 9.   9. The Barkhausen noise inspection apparatus according to claim 1, further comprising a residual stress detection unit that detects residual stress on the surface of the inspection object from Barkhausen noise detected by the noise detection sensor. .   10. The Barkhausen noise inspection device according to claim 1, wherein the inspection object is a rolling device or a rolling device part.

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