JP2008170408A - Method and device for inspecting nonmetallic inclusion in component of rolling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inspecting a nonmetallic inclusion in a component of a rolling apparatus, capable of precisely inspecting the presence of the nonmetallic inclusion in a surface layer of the component of the rolling apparatus that shortens the life of the rolling apparatus, and to provide a device therefor. <P>SOLUTION: The device for inspecting the presence of the nonmetallic inclusion in the surface layer of the component of the rolling apparatus comprises: an electromagnetic induction sensor 12 having an excitation coil 121 for providing an alternating magnetic field on the surface layer of the component of the rolling apparatus and an induction coil 122 for detecting the magnetic flux density of the alternating magnetic field provided on the surface layer of the component of the rolling apparatus; an inductance change detecting circuit 13 as an induced electromotive force detecting unit for detecting the magnitude of the induced electromotive force generated in induction coil 122; and a comparison and discrimination circuit 14 for comparing the magnitude of the induced electromotive force detected in this inductance change detecting circuit 13 with a threshold to judge the presence of the nonmetallic inclusion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling device component of a rolling device (such as a bearing ring or rolling element of a rolling bearing, a guide rail or slider or rolling element of a linear guide bearing device, a screw shaft or nut of a ball screw, or a rolling element). The present invention relates to a technique for inspecting whether or not there are non-metallic inclusions that shorten the life of a rolling device.

The bearing ring of the rolling bearing has a raceway surface on which the rolling elements roll. When the size of non-metallic inclusions existing on the surface layer of the raceway ring including this raceway surface is 500 μm or more, this is the starting point. Defects such as cracks occur in the bearing ring, resulting in shortening the life of the rolling bearing. Therefore, as a technique for inspecting whether or not non-metallic inclusions that shorten the life of a rolling bearing are present in the surface layer portion of the bearing ring, a technique for inspecting the presence or absence of non-metallic inclusions by ultrasonic flaw detection is known. (For example, see Patent Document 1 and Patent Document 2)
However, in the technique described in Patent Document 1 and Patent Document 2, for example, when the frequency of the ultrasonic wave is less than 2 MHz and the size of the nonmetallic inclusions existing on the surface layer of the raceway is 100 μm or less, the nonmetallic inclusions are used. It becomes difficult to accurately detect an object. In addition, when the frequency of the ultrasonic wave exceeds 30 MHz, the ultrasonic wave is attenuated inside the raceway ring, so that the surface layer portion from the raceway surface to a depth corresponding to 2% of the diameter of the rolling element can be accurately detected. There was a problem that it became difficult. It is also practical to deal with cases where non-metallic inclusions or defects exist at a depth deeper than the depth corresponding to 2% of the rolling element diameter from the raceway surface where the shear stress at the time of rolling contact is maximum. Is important to.

  Moreover, the rolling bearing used as a bearing which supports rolling rolls, such as a tandem rolling mill, is used in the environment where a lot of cooling water scatters. For this reason, if a part of the cooling water sprayed on the work enters the inside of the rolling bearing and enters the lubricant, the durability of the rolling bearing is greatly reduced. For example, it has been reported that when 6% of water is mixed in the lubricant, the rolling fatigue life of the bearing is reduced from a fraction of 1 to about 1/20 compared to the case where no water is mixed ( Non-patent document 1). Therefore, as a measure to prevent liquids such as cooling water from entering the inside of the rolling bearing, a contact rubber seal is attached to the chock (bearing box) in which the rolling bearing is accommodated, and the inside of the chock is sealed in a liquid-tight manner. A technique for reducing the moisture concentration in the lubricant from 40% to less than 10% (for example, see Non-Patent Document 2) has been proposed. Although it can be reduced, it has been found that the use time until the occurrence of peeling, that is, a reduction in bearing life, has not been improved much (for example, see Patent Document 5).

  FIG. 6 is a diagram for explaining the mechanism for reducing the bearing life. As shown in FIG. 6A, the elastic deformation Δh in the depth direction due to the radial load received from the rolling element T causes the raceway of the fixed side ring. When generated on the surface K, a shear stress f is generated at the contact portion between the rolling element T and the raceway surface K. Then, as shown in FIG. 6B, when the nonmetallic inclusion W is present in the surface layer portion of the raceway surface K, the nonmetallic inclusion is caused by the shear stress f generated at the contact portion between the rolling element T and the raceway surface K. When a gap S is generated around W and a large amount of moisture is contained in the lubricant on the raceway surface K at this time, the moisture in the lubricant enters the gap S, so that the metal substrate is corroded and dissolved. As a result, stress corrosion cracking and peeling easily occur on the raceway surface K.

  As a technique for preventing the adverse effects of non-metallic inclusions existing on the surface layer of the race ring including the raceway surface, the surface layer portion of the race ring including the raceway surface (the depth corresponding to 2% of the rolling element diameter from the raceway surface). There is known a technique for inspecting whether or not non-metallic inclusions having a size exceeding 500 μm exist in the surface layer part) by ultrasonic flaw detection (see, for example, Patent Documents 2-4). In addition, when water, which is a problem this time, is mixed, whether or not there is an oxide-based nonmetallic inclusion having a diameter exceeding 100 μm exists between the fixed-side raceway surface and the metal substrate by ultrasonic flaw detection. A technique for inspecting and preventing stress corrosion cracking due to water intrusion and thereby shortening the life of the bearing has been proposed (see Patent Document 5).

  However, in order to achieve a more stable and long life of the rolling bearing, it is necessary to ensure that there are no non-metallic inclusions of 100 μm or more, which are said to be ground scratches often seen in steel materials for bearings as a practical problem. Become. In order to guarantee that this level of non-metallic inclusions does not exist, it is necessary to use a high frequency of 30 MHz or higher corresponding to 1/2 of the ultrasonic wavelength, and when using the ultrasonic flaw detection method, There is a demerit such as significant attenuation. For this reason, stable detection of defects such as inclusions is limited only to the material (orbital surface) surface, and the detection sensitivity is greatly affected by the surface roughness. Further, among the nondestructive flaw detection methods, the ultrasonic flaw detection method and the radiation flaw detection method also have a practical problem that the apparatus and inspection are expensive.

A roller used for a bearing that receives a very large load, such as a steel rolling bearing, has a defect that exceeds a square root length of 0.2 mm within a range from the surface to a depth corresponding to 2% of the average roller diameter Da. In the presence of metal inclusions, peeling due to rolling fatigue is likely to occur. In addition, if there are defects exceeding the maximum length of 0.5 mm (non-metallic inclusions, etc.) within the entire cross-sectional area of the roller, cracks will occur in the roller due to repeated bending, tensile, and compressive stresses. It becomes easy to do.
Japanese Patent No. 0363984 JP 2000-130447 A JP 2004-77206 A JP 2003-139143 A JP 2000-110841 A Shinzaburo Furumura, Shinichi Shirota, Kiyoshi Hirakawa: “Rolling fatigue from surface and internal origins”, NSK Bearing Journal, NO. 636, pp. 1-10, 1977 K. YAMAMOTO, M .; YAMAZAKI, M .; AKIYAMA, K.A. FURUMURA: "Introducing of Sealed Bearings for Work Roll Necks in Rolling Mills", Processeds of the JSL International Tribology Conference, pp. 609-614, July 8-10, 1985, Tokyo, Japan

  The present invention has been made paying attention to the above-mentioned problems, and its purpose is to determine whether or not non-metallic inclusions that shorten the life of the rolling device are present in the surface layer portion of the rolling device component. An object of the present invention is to provide a non-metallic inclusion inspection method and a non-metallic inclusion inspection apparatus for rolling device parts that can be inspected with high accuracy. Another object of the present invention is to provide a method of manufacturing a rolling bearing capable of obtaining a rolling bearing in which internal defects such as non-metallic inclusions do not exist in the rolling element.

  In order to achieve the above object, the non-metallic inclusions inspection method for rolling device parts according to the first aspect of the present invention is such that the non-metallic inclusions that cause a shortened life of the rolling device are the surface layer of the rolling device parts. A method of inspecting whether or not the rolling device part is present in an AC magnetic field generated by an AC voltage applied to an excitation coil and the amplitude of an electromotive force generated in the induction coil by electromagnetic induction And measuring the amount of change of at least one of the phase and the presence or absence of the non-metallic inclusions.

The method for inspecting non-metallic inclusions in rolling device parts according to claim 2 is the method for inspecting non-metallic inclusions in rolling device parts according to claim 1, wherein the predetermined area of the raceway surface × the raceway surface. The non-metallic inclusions existing in a predetermined volume defined by a predetermined depth from the above are controlled to a predetermined dimension or less.
A non-metallic inclusion inspection method for rolling device parts according to a third aspect of the invention is the method for inspecting non-metallic inclusions of a rolling device part according to the second aspect, wherein the predetermined depth is an average diameter of the rolling elements. 2%, the predetermined dimension is the maximum length of the non-metallic inclusion, there is no defect with a square root length exceeding 200 μm, and the length is 500 μm.

According to a fourth aspect of the present invention, there is provided a non-metallic inclusion inspection method for rolling device parts according to the second aspect, wherein the predetermined depth is the rolling element average diameter. 2%, the predetermined dimension is an average diameter of non-metallic inclusions, there is no defect having a square root length exceeding 200 μm, and the average diameter is 100 μm.
The non-metallic inclusions inspection method for rolling device parts according to the invention described in claim 5 is the non-metallic inclusions inspection method for rolling device parts according to claim 2, wherein the predetermined depth is the rolling element average diameter. 2%, the predetermined dimension is an average diameter of non-metallic inclusions, there is no defect with a square root length exceeding 200 μm, and the average diameter is 50 μm.

The non-metallic inclusions inspection method for rolling device parts according to the invention described in claim 6 is the non-metallic inclusions inspection method for rolling device parts according to any one of claims 1 to 5, wherein The component is a fixed-side race.
The non-metallic inclusions inspection method for rolling device parts according to the invention of claim 7 is the rolling device parts inspection method for non-metallic inclusions of rolling device parts according to any one of claims 1 to 6. The electromagnetic induction inspection is carried out over a range from the surface of the roller to a depth corresponding to ¼ of the diameter of the rolling device component and a range of the entire cross section of the rolling device component.

  The non-metallic inclusions inspection apparatus for rolling device parts according to the invention of claim 8 inspects whether or not non-metallic inclusions that cause a shortened life of the rolling apparatus are present in the surface layer portion of the rolling device parts. An excitation coil for applying an alternating magnetic field to the surface layer portion of the rolling device component, and a magnetic flux density of the alternating magnetic field applied to the surface layer portion of the rolling device component from the excitation coil An electromagnetic induction sensor having an induction coil is provided.

A non-metallic inclusion inspection apparatus for a rolling device part according to a ninth aspect of the invention is the non-metallic inclusion inspection apparatus for a rolling device part according to the eighth aspect, wherein the rolling device part and the electromagnetic induction sensor At least one of them can rotate, linearly move, or swing.
A non-metallic inclusion inspection apparatus for rolling device parts according to claim 10 is the non-metallic inclusion inspection apparatus for rolling device parts according to claim 8 or 9, wherein the output of the electromagnetic induction sensor is subjected to data processing. And a determination unit that compares the data processed by the data processing unit with a threshold value and determines the presence or absence of non-metallic inclusions.

The non-metallic inclusions inspection device for rolling device parts according to the invention of claim 11 is the non-metallic inclusions inspection device for rolling device parts according to claim 10, wherein the display means displays the determination result of the determination unit. And at least one of storage means for storing the output of the electromagnetic induction sensor.
A non-metallic inclusion inspection apparatus for rolling device parts according to claim 12 is the non-metallic inclusion inspection apparatus for rolling device parts according to any one of claims 8 to 11, wherein the electromagnetic induction sensor. However, the electromagnetic induction inspection is performed on a range from the surface of the rolling device component to a depth corresponding to ¼ of the diameter of the rolling device component and a range of the entire cross section of the rolling device component. .

  A method for manufacturing a rolling bearing according to a thirteenth aspect of the present invention is a method for manufacturing a rolling bearing having a plurality of rolling elements between an outer ring and an inner ring, and has an average diameter of 2 from the surface of the rolling element. A rolling bearing is manufactured in which no defect having a square root length exceeding 200 μm exists in the range of% depth, and no defect having a maximum length exceeding 500 μm exists in the entire cross-sectional area of the rolling element. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, it can test | inspect accurately whether the nonmetallic inclusion which shortens the lifetime of a rolling device exists in the surface layer part of rolling device components.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a non-metallic inclusion inspection apparatus according to the first embodiment of the present invention. The non-metallic inclusion inspection apparatus shown in FIG. 1 includes an exciting coil 121 that applies an alternating magnetic field to the surface layer portion of the rolling device component 18 that is the object to be inspected, and the surface layer of the rolling device component 18 from the exciting coil 121. And an induction coil 122 for detecting the magnetic flux density of the alternating magnetic field applied to the unit, and both the coils 121 and 122 constitute the electromagnetic induction sensor 12.

  Further, the non-metallic inclusion inspection apparatus shown in FIG. 1 has an inductance change detection circuit (data processing) that detects an inductance change of the induction coil 122 (amplitude change amount or phase change amount of the induced electromotive force generated in the induction coil 122). 13) and a comparison / determination circuit 14 as a determination unit for comparing the inductance change detected by the inductance change detection circuit 13 with a preset threshold value to determine the presence or absence of non-metallic inclusions. The comparison and determination circuit 14 is configured to display non-metallic inclusions when the amplitude change amount or phase change amount of the induced electromotive force generated in the induction coil 122 is larger than the threshold value. The maximum length of the non-metallic inclusion existing in the surface layer portion of the rolling device component 18 is determined to be 500. It is adapted to determined to be equal to or greater than m. The non-metallic inclusion inspection apparatus shown in FIG. 1 includes a recording device 16 that records the determination result of the comparison determination circuit 14 on a recording medium such as recording paper, and a storage device 17 that stores the output of the electromagnetic induction sensor 12. I have. An alternating current is supplied from the alternating current power supply 11 to the exciting coil 121 of the electromagnetic induction sensor 12.

FIG. 2 is a diagram showing a schematic configuration of the electromagnetic induction sensor 12. As shown in the figure, the induction coil 122 of the electromagnetic induction sensor 12 is coaxial with the excitation coil 121 by bringing a part of the induction coil 122 into contact with the excitation coil 121. It is wound around.
When inspecting whether or not non-metallic inclusions having a maximum length exceeding 500 μm are present in the surface layer portion of a rolling device part such as a bearing ring, using the non-metallic inclusion inspection apparatus shown in FIG. First, as shown in FIG. 3, the electromagnetic induction sensor 12 is brought close to the surface of the rolling device component 18. In this state, when an alternating current is supplied to the excitation coil 121 of the electromagnetic induction sensor 12 and the alternating magnetic field 19 is applied to the surface layer portion of the rolling device component 18, an induced electromotive force is generated in the induction coil 122 of the electromagnetic induction sensor 12. To do. At this time, the induced electromotive force generated in the induction coil 122 of the electromagnetic induction sensor 12 changes in accordance with the magnetic flux density of the AC magnetic field 19 applied to the surface layer portion of the rolling device component 18, and the magnetic flux density of the AC magnetic field 19 is switched. It changes according to the size of the non-metallic inclusion existing in the surface layer portion of the moving device part 18.

  Therefore, the induced electromotive force generated in the induction coil 122 of the electromagnetic induction sensor 12 is supplied to the inductance change detection circuit 13, and the amplitude change amount or phase change amount of the induced electromotive force detected by the inductance change detection circuit 13 is set in advance. By comparing with the above threshold value, it is possible to accurately inspect whether or not non-metallic inclusions exist in the surface layer portion (region from the raceway surface to the depth of the rolling element diameter of 2%) of the rolling device component 18, and further, It is possible to accurately inspect whether or not the maximum length of the non-metallic inclusion existing in the surface layer portion of the moving device part 18 is 500 μm or more.

  In the first embodiment of the present invention described above, the display device 15 that displays the determination result of the comparison determination circuit 14, the recording device 16 that records the determination result of the comparison determination circuit 14 on a recording medium such as recording paper, and the electromagnetic Although what has the memory | storage device 17 which memorize | stores the output of the induction sensor 12 was illustrated, this invention is not limited to this. For example, it may include at least one of the display device 15, the recording device 16, and the storage device 17.

FIG. 4 is a view showing a non-metallic inclusion inspection apparatus according to the second embodiment of the present invention. The non-metallic inclusion inspection apparatus shown in FIG. 4 has a non-metallic inclusion exceeding an average diameter of 100 μm. It is used when inspecting whether or not it exists in the surface layer portion (region from the raceway surface to the depth of the rolling element average diameter of 2%) including the outer ring.
The non-metallic inclusion inspection apparatus according to the second embodiment includes a turntable 21 for mounting an outer ring 20 of a rolling bearing, an electromagnetic induction sensor 12 disposed above the turntable 21, and the electromagnetic induction sensor. A sensor swing mechanism 22 that swings 12 around the Z axis (arrow θ _Z direction in the figure), and a sensor lift that drives the electromagnetic induction sensor 12 up and down in the Z axis direction in the figure via the sensor swing mechanism 22. A mechanism 23 and a sensor positioning mechanism 24 for positioning the sensor 12 by moving the electromagnetic induction sensor 12 in the X-axis direction and the Y-axis direction in the drawing are provided. The turntable 21 is illustrated by a positioning mechanism 25 for positioning the outer ring 20. It is movable in the middle X-axis direction.

The electromagnetic induction sensor 12 detects an excitation coil 121 (see FIG. 2) for applying an AC magnetic field to the surface layer portion of the outer ring 20 and a magnetic flux density of the AC magnetic field applied from the excitation coil 121 to the surface layer portion of the outer ring 20. The induction coil 122 is configured.
When inspecting whether or not non-metallic inclusions having an average diameter of more than 100 μm are present in the surface layer portion of the outer ring 20 including the raceway surface using the non-metallic inclusion inspection apparatus shown in FIG. Is placed on the turntable 21. Next, after driving the sensor swing mechanism 22, the sensor elevating mechanism 23, the sensor positioning mechanism 24, and the positioning mechanism 25 to bring the electromagnetic induction sensor 12 close to the raceway surface of the outer ring 20, the excitation coil 121 of the electromagnetic induction sensor 12 is applied. When an alternating current is supplied and an alternating magnetic field is applied to the surface layer portion of the outer ring 20, an induced electromotive force is generated in the induction coil 122 of the electromagnetic induction sensor 12. At this time, the magnitude of the induced electromotive force generated in the induction coil 122 changes according to the magnetic flux density of the AC magnetic field applied to the surface layer portion of the outer ring 20, and the magnetic flux density of the AC magnetic field exists in the surface layer portion of the outer ring 20. It varies depending on the size of non-metallic inclusions.

  Therefore, by comparing the magnitude of the induced electromotive force generated in the induction coil 122 of the electromagnetic induction sensor 12 with a preset threshold value, the surface layer portion of the outer ring 20 (from the raceway surface to the depth of the rolling element average diameter of 2%). The non-metallic inclusions can be accurately inspected in the region), and further, it can be accurately inspected whether the average diameter of the non-metallic inclusions existing in the surface layer portion of the outer ring 20 exceeds 100 μm.

FIG. 5 is a view showing a non-metallic inclusion inspection apparatus according to a third embodiment of the present invention. The non-metallic inclusion inspection apparatus shown in FIG. It is used when inspecting whether or not it exists in the surface layer portion (region from the raceway surface to the depth of the rolling element average diameter of 2%) including the inner ring.
The non-metallic inclusion inspection apparatus according to the third embodiment includes a turntable 21 for placing an inner ring 26 of a rolling bearing, an electromagnetic induction sensor 12 disposed above the turntable 21, and the electromagnetic induction sensor. The sensor oscillating mechanism 22 that can oscillate 12 around the Z axis (arrow θ _Z direction in the figure), and the electromagnetic induction sensor 12 is driven up and down in the Z axis direction in the figure via the sensor oscillating mechanism 22. The sensor elevating mechanism 23 and a sensor positioning mechanism 24 for positioning the sensor 12 by moving the electromagnetic induction sensor 12 in the X-axis direction and the Y-axis direction in the figure are configured. The electromagnetic induction sensor 12 is a surface layer of the inner ring 26. And an induction coil for detecting the magnetic flux density of the AC magnetic field applied to the surface layer portion of the inner ring 26 by the excitation coil 121. And a 22..

  When inspecting whether or not non-metallic inclusions having an average diameter of more than 50 μm are present on the surface layer portion of the inner ring 26 including the raceway surface using the non-metallic inclusion inspection apparatus shown in FIG. Is placed on the turntable 21. Next, the sensor swing mechanism 22 (in this embodiment, the turntable 21 is rotated and the sensor swing mechanism 22 is fixed), the sensor lifting mechanism 23 and the sensor positioning mechanism 24 are driven to move the electromagnetic induction sensor 12 to the inner ring 26. When an alternating current is applied to the excitation coil 121 of the electromagnetic induction sensor 12 and an alternating magnetic field is applied to the surface layer portion of the inner ring 26 after approaching the raceway surface, an induced electromotive force is generated in the induction coil 122 of the electromagnetic induction sensor 12. At this time, the magnitude of the induced electromotive force generated in the induction coil 122 changes according to the magnetic flux density of the AC magnetic field applied to the surface layer portion of the inner ring 26, and the magnetic flux density of the AC magnetic field exists in the surface layer portion of the inner ring 26. It varies depending on the size of non-metallic inclusions.

  Therefore, by comparing the magnitude of the induced electromotive force generated in the induction coil 122 of the electromagnetic induction sensor 12 with a preset threshold value, the surface layer portion of the inner ring 26 (from the raceway surface to the depth of the rolling element average diameter of 2%). It is possible to inspect whether or not non-metallic inclusions are present in the region), and it is possible to accurately inspect whether or not the average diameter of non-metallic inclusions existing in the surface layer portion of the inner ring 26 exceeds 50 μm.

FIG. 7 is a diagram showing a schematic configuration of a non-metallic inclusion inspection apparatus according to the fourth embodiment of the present invention. The non-metallic inclusion inspection apparatus shown in FIG. 7 includes an electromagnetic induction sensor 12 and an electromagnetic induction unit 31. A computer unit 32, a liquid crystal display (LCD) 33, a sensor positioning device 34, a roller rotating device 35, and a positioning control device 36.
In the electromagnetic induction sensor 12, an excitation coil 121 and a detection induction coil 122 are integrated, and the configuration is such that the leakage magnetic flux is reduced as much as possible and the mutual inductance is increased. For this reason, unlike a general eddy current flaw detection, the magnetic flux reaches not only the surface defect but also the interior below the surface, so that the inductance of the induction coil 122 changes due to the magnetic flux change due to the internal defect.

The electromagnetic induction unit 31 includes an excitation oscillation circuit 311 that supplies an alternating current to the excitation coil 121 of the electromagnetic induction sensor 12. Further, the electromagnetic induction unit 31 is configured to detect a change in inductance of the induction coil 122 by the detection circuit 312, amplify the detection result by the amplification circuit 313, and send it to the computer unit 32.
The computer unit 32 includes an AD converter 321, a CPU 322, a timer pulse unit 323, a PIO 324, an LCD driver 325, a memory (not shown), and the like. The signal amplified by the amplifier circuit 313 is converted into a digital signal by the AD converter 321. And is converted into data together with position information of the sensor positioning device 34.

If calibration is performed using the cylindrical roller 37 into which an artificial defect has been introduced or a sample in which an internal defect has been found by ultrasonic inspection, the size of the defect can also be known by electromagnetic induction inspection.
Ultrasonic inspection requires underwater ultrasonic waves, and thus costs up to the cost of the rust preventive, whereas the electromagnetic induction type does not require such costs.
Regarding the inspection speed, the speed of sound and electromagnetic speed are not comparable, but in reality, inspection of a certain volume or more is required, and scanning of the sensor and the subject is required. Absent. However, in general, the ultrasonic inspection is a pulse echo method, and the spot diameter in the steel of the high-frequency focusing probe that can detect inclusions in the steel that are small enough to affect the life of the high-pressure rolling surface depends on the defect to be detected. Therefore, it is necessary to reduce the scanning pitch to about the size of the defect, so that a scanning pitch of about the size of the defect is required, and the inspection time becomes more burdensome as the subject volume and the subject area are larger.

Ultrasonic inspection requires the return of ultrasonic echoes and is a pinpoint method, whereas the electromagnetic induction inspection method is a method that captures magnetic flux disturbance as a change in inductance, so it is bulky. Therefore, there is a high possibility that a large scanning pitch can be obtained, and it can be predicted that the inspection time will be considerably faster.
The high-frequency circuit required for ultrasonic waves requires a lower frequency for electromagnetic induction (ultrasonic waves are around 50 MHz, whereas for electromagnetic induction, the frequency is 1 KHz to 1 MHz. Caused by the difference).

  In electromagnetic induction inspection, the depth to be inspected and the size of detectable inclusions can be determined by the excitation voltage and frequency, and it is possible to inspect while changing the sensitivity to depth by switching between multiple frequencies and voltages. In addition, the inspection can be performed at a certain frequency and amplitude suitable for the subject, and the sensitivity to the depth can be changed by computer processing (software). Also, the sensitivity to depth can be changed by changing the sensor coil, but in this example, the sensor is not replaced because the speed is important.

  In this example, it is divided into a range from the rolling device component surface to a position deeper than the position where the maximum shear stress is generated (a 1/4 depth position of the rolling device component diameter D) and a range of the entire cross section of the rolling device component. When performing the electromagnetic induction inspection, the inspection up to D / 4 and the inspection of the entire cross section are selectively used mainly due to the difference in frequency. That is, up to D / 4 close to the vicinity of the surface, excitation induction is performed at a relatively high frequency, and inspection is performed so as to detect relatively small defects.

In the entire cross-section inspection, an inspection is performed to detect a relatively large defect in which the magnetic flux is not easily attenuated to the center of the rolling device part at a relatively low frequency.
The roller rotating device 35 for cylindrical rollers shown in FIG. 7 is driven by a servo motor capable of controlling the rotation speed and position. The roller rotating device 35 rotates a cylindrical roller 37 as an object, and at the same time, a sensor positioning device 34. Therefore, the entire raceway surface of the cylindrical roller 37 can be scanned by moving the electromagnetic induction sensor 12 in the axial direction of the cylindrical roller 37.

As an object to be calibrated, a cylindrical roller 37 having an artificial defect 38 as shown in FIG. 8 is used.
In the electromagnetic induction inspection, an internal defect generated in a subject is detected by a disturbance of magnetic flux by a detection side coil (induction coil). Since the magnetic flux disturbance is relative, it is necessary to compare normal and defective products using the same type of rollers.

In the sample shown in FIG. 8A, an artificial defect is formed by machining a hole having a diameter of 0.2 mm from the end face of the roller at a certain depth by electric discharge machining in a portion close to the surface. Further, the sample shown in FIG. 8B is a sample in which a hole having a diameter of 0.5 mm is processed from the end face near the center to a certain depth by electric discharge machining to form an artificial defect.
In this example, the electromagnetic induction inspection of the calibration sample in which the artificial defect is formed is performed before the electromagnetic induction inspection of the subject. Specifically, while adjusting the oscillation frequency, oscillation voltage, gain of the detection amplifier, etc., record the detected waveform or voltage indicating magnetic flux disturbance as well as the relative position of the electromagnetic induction sensor and the subject to detect defects near the surface. And search for an oscillation frequency and threshold value suitable for defects near the center.

In addition, if possible, if non-destructive inspection such as ultrasonic inspection and X-ray CT inspection is allowed to contain defects, and using natural defects whose dimensions and positions are specified, calibration accuracy can be improved. Defect dimensions can also be measured.
The electromagnetic induction inspection detects a magnetic flux disturbance, but can detect a very small defect compared to the magnitude of the magnetic flux. This is a significant difference from ultrasonic inspection, and even small defects can be detected with a rough scanning pitch, and high-speed inspection can be performed. Further, unlike the general eddy current inspection, the electromagnetic induction inspection method used in this example is a type of inspection device and probe coil that transmits magnetic flux inside the metal, so that even internal defects can be detected.

If the diameter of the roller is a certain size or less, it is possible to inspect only the entire cross section in detecting defects in the vicinity of the surface and in the entire cross section.
Moreover, although it takes time, two inspections may be performed by preparing sensor coils for the entire cross-section inspection and the surface vicinity inspection.
FIG. 9 is a diagram showing a schematic configuration of a non-metallic inclusion inspection apparatus according to the fifth embodiment of the present invention. The non-metallic inclusion inspection apparatus shown in FIG. 9 includes an electromagnetic induction sensor 12 and an electromagnetic induction unit 31. , A sensor positioning device 34, a roller rotating device 35, a positioning control device 36, a controller 40, and a digital signal processing unit 41.

  The controller 40 outputs a control signal for controlling the scanning pitch and speed of the sensor probe scanning device and the roller rotating device 35 to the positioning control device 36. The controller 40 outputs a signal for setting the gain of the amplifier to the electromagnetic induction unit 31 and also outputs a signal for setting the scanning position and the determination condition (threshold) to the digital signal processing unit 41.

The digital signal processing unit 41 includes an AD converter 411 and a determination circuit 412. However, if the determination circuit 412 includes a CPU and software, the digital signal processing unit 41 is configured by a hardware digital circuit. May be.
In the fifth embodiment shown in FIG. 9, the detection sensitivity and threshold value for the defect size in the vicinity of the surface and the entire cross section for the heat-treated polished finished roller having a predetermined roller diameter are obtained by the same method as in the fourth embodiment. In this case, setting values of various setting signals supplied from the controller 40 to the electromagnetic induction unit 31 and the digital signal processing unit 41 can be obtained.

  When the diameter of the cylindrical roller 37 is 20 mm, if there is a defect of 0.1 mm or more within a depth of 5 mm from the surface of the cylindrical roller 37, a defect (NG) is determined and 0.3 mm over the entire cross section of the cylindrical roller 37. If the defect is set when the above defects exist, there is no defect having a square root length exceeding 0.2 mm within the range of 2% depth of the average diameter Da of the rolling element, and the rolling element It is possible to obtain a rolling bearing in which it is ensured that there is no defect having a maximum length exceeding 0.5 mm within the entire cross-sectional area.

During the operation of the inspection apparatus shown in FIGS. 7 and 9, it is preferable to periodically perform calibration to confirm that the same output can be obtained with a sample having an artificial defect.
FIG. 10 is a diagram showing a schematic configuration of a non-metallic inclusion inspection apparatus according to the sixth embodiment of the present invention. As shown in FIG. 10, the non-metallic inclusion inspection apparatus according to the sixth embodiment , Electromagnetic induction sensor 12, pulleys 51 a and 51 b, pulley driving belt 52, motor 53, control amplifier 54, control device 55, linear guide device 56, controller 57 and rotary encoder 58.

A bearing ring 50 as a subject is placed on the peripheral surface portions of the pulleys 51a and 51b. These pulleys 51a and 51b are rotationally driven by a pulley driving belt 52. When the pulleys 51a and 51b rotate, the bearing ring 50 also rotates in synchronization therewith.
A motor 53 that travels and drives the pulley driving belt 52 is controlled by a control device 55 via a control amplifier 54, and a linear guide device 56 that moves the electromagnetic induction sensor 12 in the axial direction of the bearing ring 50 via a servo motor (not shown). Is controlled by the controller 57.

The rotational position detection signal output from the rotary encoder 58 that detects the rotational position of the bearing ring 50 is supplied to the controller 57.
When the controller 57 detects that the bearing ring 50 has made one rotation based on the rotational position detection signal from the rotary encoder 58, the controller 57 controls the servo motor based on a command from the control device 55, and the electromagnetic induction sensor 12 is connected to the shaft of the bearing ring 50. Move a certain dimension in the direction. Thereby, flaw detection of the entire bearing ring is performed by the electromagnetic induction sensor 12.

  Therefore, in the sixth embodiment, as in the first to fifth embodiments described above, it is possible to accurately inspect whether minute defects such as non-metallic inclusions are present in the bearing ring. it can.

It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows schematic structure of an electromagnetic induction sensor. It is a figure which shows the alternating current magnetic field provided to the surface layer part of rolling device components from the exciting coil of an electromagnetic induction sensor. It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the mechanism in which a bearing life falls. It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 4th Embodiment of this invention. It is a figure which shows an example of the sample for a calibration which has an artificial defect. It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 5th Embodiment of this invention. It is a figure which shows schematic structure of the nonmetallic inclusion inspection apparatus which concerns on the 6th Embodiment of this invention.

Explanation of symbols

11 AC Power Supply 12 Electromagnetic Induction Sensor 121 Excitation Coil 122 Induction Coil 13 Inductance Detection Circuit (Data Processing Unit)
14 Comparison determination circuit (determination unit)
DESCRIPTION OF SYMBOLS 15 Display apparatus 16 Recording apparatus 17 Memory | storage device 21 Turntable 22 Sensor swing mechanism 23 Sensor raising / lowering mechanism 24 Sensor positioning mechanism 31 Electromagnetic induction unit 311 Excitation oscillation circuit 312 Detection circuit 313 Amplification circuit 32 Computer unit 321 AD converter 322 CPU
323 Timer pulse unit 324 PIO
325 LCD driver 33 Liquid crystal display device 34 Sensor positioning device 35 Roller rotation device 36 Positioning control device 37 Cylindrical roller 38 Artificial defect 40 Controller 41 Digital signal processing unit 411 AD converter 412 Determination circuit 51a, 51b Pulley 52 Pulley driving belt 53 Motor 54 Control Amplifier 55 Control Device 56 Linear Guide Device 57 Controller 58 Rotary Encoder

Claims (13)

  A method for inspecting whether or not non-metallic inclusions that cause a shortened life of a rolling device are present in a surface layer portion of the rolling device component, wherein the rolling device component is applied by an alternating voltage applied to an exciting coil. A rolling device component, characterized by being placed in an alternating magnetic field generated and measuring the amount of change of at least one of the amplitude and phase of an electromotive force generated by electromagnetic induction to inspect for the presence of the non-metallic inclusions Non-metallic inclusion inspection method.   2. The non-metallic inclusion inspection method for rolling device parts according to claim 1, wherein the non-metallic inclusion is present in a predetermined volume defined by a predetermined area of the raceway surface × a predetermined depth from the raceway surface. Is controlled to be equal to or less than a predetermined dimension. A non-metallic inclusion inspection method for rolling device parts.   3. The method for inspecting non-metallic inclusions in a rolling device part according to claim 2, wherein the predetermined depth is 2% of an average diameter of the rolling elements, and there is no defect having a square root length exceeding 200 μm. A method for inspecting non-metallic inclusions in a rolling device part, characterized in that the dimension is the maximum length of non-metallic inclusions and the length is 500 μm.   3. The method for inspecting non-metallic inclusions in a rolling device part according to claim 2, wherein the predetermined depth is 2% of an average diameter of the rolling elements, and there is no defect having a square root length exceeding 200 μm. A method for inspecting non-metallic inclusions in a rolling device part, characterized in that the dimension is an average diameter of non-metallic inclusions and the average diameter is 100 μm.   3. The method for inspecting non-metallic inclusions in a rolling device part according to claim 2, wherein the predetermined depth is 2% of an average diameter of the rolling elements, and there is no defect having a square root length exceeding 200 μm. A method for inspecting non-metallic inclusions in a rolling device part, wherein the dimension is an average diameter of non-metallic inclusions, and the average diameter is 50 μm.   The non-metallic inclusion inspection method for a rolling device part according to any one of claims 1 to 5, wherein the rolling device part is a fixed-side raceway ring. Inclusion inspection method.   In the non-metallic inclusions inspection method for a rolling device part according to any one of claims 1 to 6, a range from the surface of the rolling device part to a depth corresponding to ¼ of the diameter of the rolling device part; A method for inspecting non-metallic inclusions in a rolling device part, comprising performing an electromagnetic induction inspection over a range of the entire cross section of the rolling device part.   An apparatus for inspecting whether or not non-metallic inclusions that cause a shortened life of a rolling device are present in the surface layer portion of the rolling device component, and for applying an alternating magnetic field to the surface layer portion of the rolling device component A rolling device comprising an electromagnetic induction sensor having a coil and an induction coil for detecting a magnetic flux density of an alternating magnetic field applied to a surface layer portion of the rolling device component from the exciting coil Non-metallic inclusion inspection system for parts.   9. The non-metallic inclusion inspection apparatus for a rolling device part according to claim 8, wherein at least one of the rolling device part and the electromagnetic induction sensor is rotatable, linearly movable, and swingable.   A data processing unit that performs data processing on the output of the electromagnetic induction sensor, and a determination unit that compares the data processed by the data processing unit with a threshold value to determine the presence or absence of non-metallic inclusions. The non-metallic inclusion inspection apparatus for rolling device parts according to claim 8 or 9.   The non-metallic inclusion inspection of rolling device parts according to claim 10, further comprising at least one of display means for displaying the determination result of the determination section and storage means for storing the output of the electromagnetic induction sensor. apparatus.   The electromagnetic induction sensor performs an electromagnetic induction inspection on a range from the surface of the rolling device component to a depth corresponding to ¼ of the diameter of the rolling device component and a range of the entire cross section of the rolling device component. The non-metallic inclusion inspection apparatus for rolling device parts according to any one of claims 8 to 11.   A method for manufacturing a rolling bearing having a plurality of rolling elements between an outer ring and an inner ring, wherein the defect has a square root length exceeding 200 μm within a range of 2% depth of the average diameter of the rolling elements from the surface of the rolling element. And a rolling bearing in which it is ensured that there is no defect having a maximum length exceeding 500 μm in the entire cross-sectional area of the rolling element.

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