JP6160948B2 - Quenching depth measuring probe and quenching depth measuring method using the quenching depth measuring probe - Google Patents

Description

  The invention according to the present application relates to a quenching depth measurement probe used when non-destructively inspecting the quenching depth in a workpiece subjected to quenching processing, and a production line for a cylindrical workpiece having a quench hardened layer. The quenching depth measurement method performed using the quenching depth measurement probe in FIG.

  As a method for increasing the strength of a metal, there is a method in which a workpiece such as a steel material is heated using a high-frequency induction heating method and is hardened by quenching. The mechanical properties of the workpiece vary depending on the depth of the hardened hardened layer. Therefore, for the purpose of quality assurance of the workpiece, it may be necessary to measure the depth of the hardened and hardened layer after production.

  Conventionally, the depth of a hardened hardened layer applied to a workpiece is measured by actually cutting a randomly sampled workpiece and measuring the hardness in the depth direction on the cut surface using a surface hardness tester. I was going. In this inspection method involving cutting, it takes time to obtain the inspection result, and the sample work cannot be used as a product. Therefore, there is a problem that not all products can be inspected.

  Therefore, various methods for measuring the depth of the hardened hardened layer of the workpiece by nondestructive methods using ultrasonic waves and eddy currents have been studied. For example, Patent Document 1 relates to a quenching depth measurement method that measures the depth of a hardened hardened layer of a steel material in a nondestructive manner. The steel material is magnetized in a direction along the surface by a low-frequency alternating magnetic field generated by an exciting coil. Eddy current is generated, the induction magnetic field induced by the eddy current is detected by the detection coil, and the output voltage of the detection coil is compared with the correlation data of the known quench hardening layer depth and the output voltage, A method of calculating the depth of the hardened and hardened layer of the target steel material is adopted.

  In this Patent Document 1, as a practical probe capable of measuring the quenching depth only along the surface of a steel material, one of U-shaped yokes having a pair of parallel contact cores in contact with the steel material surface is provided. A configuration is disclosed in which an excitation coil is wound around a contact core, a detection coil is wound around the other contact core, and an external magnetic field detection means is disposed between the tips of the contact cores.

  The depth measurement of the hardened hardened layer by the eddy current method as disclosed in Patent Document 1 is performed by magnetizing a workpiece by a low-frequency AC magnetic field generated by an exciting coil and applying an eddy current to the magnetized workpiece. The induced magnetic field generated by the eddy current is detected by the detection coil. In this measurement, the low-frequency AC magnetic field generated by the exciting coil magnetizes not only the workpiece but also the yoke around which the exciting coil is wound, and an eddy current is also generated in the yoke itself. The yoke at this time is subjected to heating. However, as disclosed in Patent Document 1, when measuring the depth of the hardened layer on the outer surface of the workpiece, the measuring probe is exposed to the atmosphere. Therefore, the generated heat is dissipated into the atmosphere, and there is no problem due to heat generation.

Japanese Patent No. 2002-14081

  However, when the method for measuring the depth of the hardened hardened layer disclosed in Patent Document 1 is simply used for measuring the depth of the hardened hardened layer on the inner peripheral surface of the cylindrical workpiece, the measurement probe is blocked. It is necessary to perform measurement by placing it inside a cylindrical workpiece close to the environment. That is, when the measurement probe simply applying the technical idea of Patent Document 1 is placed inside the cylindrical workpiece and the measurement is performed, Joule heat generated in the yoke is likely to be trapped in the cylindrical workpiece. When the yoke heats abnormally due to the Joule heat, the exciting coil and the detection coil wound around the yoke are overheated, and the insulating resin film of these coils melts, causing a problem such as a short circuit.

  Moreover, the depth measurement of the hardening hardening layer by the eddy current method disclosed in Patent Document 1 is performed by measuring the output voltage of the detection coil of the induction magnetic field induced by the eddy current generated in the workpiece. However, as described above, when the yoke is abnormally heated by Joule heat, not only the yoke but also the detection coil and the workpiece rise in temperature. These yokes, detection coils, and workpieces increase in electromagnetic resistance as the temperature rises, and their electrical and magnetic characteristics change. For this reason, when measuring the depth of the hardened layer on the inner wall of the cylindrical workpiece, compared to the case of measuring the depth of the hardened layer on the outer surface of the workpiece, the depth of the actual hardened layer of the workpiece Accordingly, it is difficult to measure the output voltage according to the accuracy with high accuracy, and there is a problem that the reliability of the measurement accuracy is remarkably lowered.

  Therefore, even when measuring the depth of the hardened hardened layer on the inner wall surface of a cylindrical workpiece, the temperature rise of the yoke, coil, workpiece, etc. is suppressed, and a non-destructive method is used for safety and high accuracy. Development of an apparatus and method that can measure the depth of a hardened hardened layer is desired.

  As a result of diligent research, the inventors of the present invention can measure the depth of the hardened hardened layer on the inner wall surface of the cylindrical workpiece safely and with high accuracy by adopting the following quenching depth measurement probe. I thought of that.

The quenching depth measurement probe according to the present invention is arranged inside a cylindrical workpiece to measure the quenching depth of the inner wall surface of the cylindrical workpiece, and is divided into two or more. A first flat plate portion having an insulating layer constituting material interposed between the divided surfaces of each piece is arranged at one end of the columnar core portion, and insulation is performed between the divided surfaces of each piece divided into two or more pieces. a core of the second flat plate portion formed by interposed a layer components which arranged in parallel with the other end to the first flat plate portion of the columnar core, is wound around the outer periphery of the columnar core portion of the core, Measured by detecting an induction magnetic field of the excitation coil that magnetizes the cylindrical workpiece, a detection coil that is wound around the outer periphery of the columnar core portion of the core, and that detects an induction magnetic field generated by the magnetization. Cylindrical workpiece from output voltage and known electromagnetic property information on equivalent materials of the cylindrical workpiece A quenching depth specifying means for specifying the quenching depth of the steel, and the quenching depth specifying means is specific to a non-quenched material not subjected to quenching and a completely quenched material subjected to quenching. Determines the quenching depth of the cylindrical workpiece from known electromagnetic characteristics information including the estimated voltage value of the detection coil obtained using the initial magnetization curve and conductivity, which are standard physical property values, and the output voltage of the detection coil characterized in that it.

  In the quenching depth measurement probe according to the present invention, each piece of the first and second flat plate portions has a central angle of 360 ° / n (n is 2 or more) with the plane center of each flat plate portion as a center point. It is preferable to divide by (integer).

  In the quenching depth measurement probe according to the present invention, it is preferable that each flat plate portion has a plane center of each flat plate portion arranged on an extension line of a central axis of the columnar core portion.

  In the quenching depth measurement probe according to the present invention, the columnar core portion is centered on the center in the radial cross section of the cylindrical workpiece at a position corresponding to the dividing surface of the first and second flat plate portions. The central angle is divided into n pieces having a central angle of 360 ° / n (n is an integer of 2 or more), and an insulating layer constituting material is interposed between the divided surfaces of the pieces. More preferred.

  In the quenching depth measurement probe according to the present invention, it is preferable that the detection coil is positioned inside the excitation coil and is wound around an outer peripheral surface of the columnar core portion.

  In the quenching depth measurement probe according to the present invention, the insulating layer constituent material preferably has a thickness of 3.0 mm or less.

  In the quenching depth measurement probe according to the present invention, the insulating layer constituting material is an epoxy resin, a polyimide resin, an aramid resin, a benzotriazole resin, a polyphenylene oxide resin, or a skeletal agent in which a skeletal material is included in these resins. More preferably, it is composed of any one of the contained resins.

  The quenching depth measurement probe according to the present invention is a quenching depth measurement probe for measuring a quenching depth of the cylindrical workpiece having a tapered shape on an inner wall surface, and a columnar core portion constituting the core. In a cross section including the center axis of each flat plate portion and the center of each flat plate portion, an imaginary line connecting the outer edge of the first flat plate portion and the outer edge of the second flat plate portion arranges the core inside the cylindrical workpiece. In the state, it is more preferable that the cylindrical workpiece is formed so as to be substantially parallel to the tapered shape of the inner wall surface of the cylindrical workpiece.

  The quenching depth measurement method in the present invention is a method performed in a production line of a cylindrical workpiece having a quench hardened layer, and the inner wall surface is heated using a high-frequency induction heating method to perform quenching. The above-mentioned quenching depth measurement probe is placed in the inside of the cylindrical workpiece, and the cylindrical workpiece is magnetized by the excitation coil of the quenching depth measurement probe, and the induced magnetic field generated by the magnetization is generated. Is detected by the detection coil, and the depth of the hardened and hardened layer of the cylindrical workpiece is specified based on the output voltage detected by the detection coil, and then the quenching depth measurement probe is connected to the inside of the cylindrical workpiece. It is characterized by evacuating from.

  According to the quenching depth measurement probe according to the present application, the first and second flat plate portions constituting the core are divided into two or more pieces, and the insulating layer constituting material between the divided surfaces of each piece. With this configuration, the eddy current generated in the core itself is remarkably suppressed, and the heat generation of the core itself can be mitigated. Thus, by reducing the eddy current generated in the core itself, the repulsive magnetic field generated in the direction opposite to the magnetic field direction by the exciting coil can be reduced, and the disturbance of the voltage waveform detected by the detection coil is suppressed. it can. As a result, the accuracy of the output voltage detected by the detection coil can be increased, and the depth of the hardened and hardened layer can be accurately measured.

  Furthermore, according to the present invention, since the heat generation of the core itself can be mitigated, even if the measurement probe is placed inside the cylindrical workpiece and the measurement is performed, the temperature rise of the core, the detection coil, and the workpiece It is possible to effectively suppress the fluctuation of electrical and magnetic characteristics, and to measure the depth of the hardened hardened layer based on the output voltage of the detection coil with high accuracy. Become.

  Further, according to the quenching depth measuring method of the present invention, the above-described quenching depth measuring probe is placed inside the cylindrical workpiece which is heated and hardened by using the high frequency induction heating method. , The cylindrical workpiece is magnetized by the excitation coil of the quenching depth measurement probe, the induction magnetic field generated by the magnetization is detected by the detection coil, and based on the output voltage detected by the detection coil After specifying the depth of the hardened hardening layer of the cylindrical workpiece, by retracting the quenching depth measurement probe from the inside of the cylindrical workpiece, in the production line of the cylindrical workpiece with the hardened hardening layer, It becomes possible to inspect the entire amount of the cylindrical workpiece quickly and easily. Therefore, it is possible to improve the reliability of the quality of the cylindrical workpiece as a product.

It is a schematic diagram of a quenching depth measurement probe as an embodiment according to the present invention. It is a schematic sectional drawing which shows the state which has arrange | positioned the quenching depth measurement probe of FIG. 1 inside the cylindrical workpiece | work used as a measuring object. It is a graph which contrasts the analytical value used for quenching depth measurement, and the experimental value which measured the test material for verification. It is a relative magnetic permeability distribution by simulation when the inner wall surface of the taper hub bearing to be measured is magnetized using the quenching depth measurement probe of the example. It is magnetic flux density distribution by simulation when the inner wall surface of the taper hub bearing used as a measuring object is magnetized using the probe for quenching depth measurement of an Example. It is the current density distribution on the core surface by simulation when energizing the exciting coil. It is a Joule loss density distribution around the core surface by simulation when energizing the exciting coil.

  First, a quenching depth measurement probe according to the present invention will be described in detail, and then a quenching depth measurement method in a production line using the quenching depth measurement probe will be described in detail. The quenching depth measuring probe according to the present application is arranged inside a cylindrical workpiece to measure the quenching depth of the inner wall surface of the cylindrical workpiece in a nondestructive manner. The quenching depth measurement probe according to the present application includes a first flat plate portion at one end of the columnar core portion, a second flat plate portion at the other end of the columnar core portion, and the first and second It comprises a core in which flat plate portions are arranged in parallel to each other, a detection coil for detecting an induced magnetic field, and an excitation coil for magnetizing a cylindrical workpiece, wound around the outer periphery of the columnar core portion of the core. And as for the probe for quenching depth measurement which concerns on this application, the 1st and 2nd flat plate part divides | segments into two or more pieces, and through the insulating layer constituent material between the division surfaces of the said each piece It is configured.

  A preferred embodiment of a quenching depth measurement probe according to the present invention will be described below with reference to FIGS. 1 is a schematic diagram of a quenching depth measurement probe 1 as an embodiment according to the present invention. FIG. 2 is a diagram illustrating the placement of the quenching depth measurement probe 1 of FIG. 1 inside a cylindrical workpiece 2 to be measured. The schematic sectional drawing which shows the state which carried out is shown.

  The quenching depth measurement probe 1 according to the present invention is heated using a high-frequency induction heating method and subjected to a quenching process, thereby measuring a cylindrical workpiece 2 having a hardened hardened layer formed on at least the inner wall surface 21. As an object, the depth of the hardened and hardened layer on the inner wall surface 21 of the cylindrical workpiece 2 is measured to inspect whether the depth of the hardened and hardened layer is a desired depth.

  In this embodiment, as shown in FIG. 2, a tapered hub bearing having a tapered shape on the inner wall surface 21 is used as an example of the cylindrical workpiece 2. Specifically, the tapered hub bearing in the present embodiment has a cylindrical shape with a substantially circular cross section, and has a tapered shape in which the inner wall surface 21 tapers at a predetermined ratio from one end side to the other end side. Has been. The tapered hub bearing shown in FIG. 2 is formed such that the opening dimension (inner diameter) S1 on one end side is larger than the opening dimension (inner diameter) S2 on the other end side.

  In addition, the cylindrical workpiece 2 in the present invention is not limited to the above-described tapered hub bearing, and may be a cylindrical cylinder having substantially the same opening dimension (inner diameter) at one end side and the other end side. . The tapered hub bearing described above has a substantially circular cross section, but is not limited to this, and the cross section may be any shape such as an ellipse or a polygon. That is, the workpiece to be measured using the quenching depth measurement probe according to the present invention may have any shape as long as it has a cylindrical shape.

  Here, the configuration of the quenching depth measurement probe 1 according to the present embodiment will be described. The quenching depth measurement probe 1 includes a columnar core portion 11, a core 10 including first and second flat plate portions 12 and 13, a detection coil 3 wound around the columnar core portion 11, and excitation. The coil 4 is provided.

  The core 10 includes a columnar core portion 11, a first flat plate portion 12 disposed at one end 11 </ b> A of the columnar core portion 11, and a second flat plate portion 13 disposed at the other end 11 </ b> B of the columnar core portion 11. Composed. It is preferable that the said 1st flat plate part 12 and the 2nd flat plate part 13 are provided in the columnar core part 11 so that it may become mutually parallel. In the first flat plate portion 12 and the second flat plate portion 13, it is preferable that the plane centers 12 </ b> C and 13 </ b> C of the flat plate portions 12 and 13 are arranged on an extension line of the central axis 11 </ b> C of the columnar core portion 11.

  The columnar core portion 11 and the flat plate portions 12 and 13 may be integrally formed, or may be separately formed and integrally formed by fixing the respective portions. The core 10 composed of the columnar core portion 11 and the flat plate portions 12 and 13 is preferably composed of any material such as permalloy, electromagnetic steel plate, soft ferrite, permender, pure iron, carbon steel, or other soft magnetic material. . These materials such as permalloy, magnetic steel sheet, soft ferrite, permender, pure iron, carbon steel and other soft magnetic materials can provide the detection coil 3 and the excitation coil 4 in that a saturation magnetic flux density can be obtained in a low magnetic field. Suitable as a material to wind.

  An excitation coil 4 and a detection coil 3 are wound around the outer periphery of the columnar core 11 constituting the core 10 described above. The exciting coil 4 generates a magnetic field when an alternating current is applied, and magnetizes the inner wall surface 21 of the cylindrical workpiece 2 in which the quenching depth measurement probe 1 is disposed. The detection coil 3 detects an induced magnetic field induced by an eddy current generated on the inner wall surface 21 of the cylindrical workpiece 2 magnetized by the excitation coil 4.

  The detection coil 3 and the excitation coil 4 are arranged concentrically or coaxially. Specifically, the detection coil 3 is wound around the outer peripheral surface of the columnar core portion 11 such that the winding direction is substantially perpendicular to the axial direction of the central axis 11C of the columnar core portion 11. Then, on the outer peripheral surface of the wound detection coil 3, the exciting coil 4 is arranged such that the winding direction is substantially perpendicular to the axial direction of the central axis 11 </ b> C of the columnar core portion 11, similarly to the detection coil 3. Is wound. As in the present embodiment, the detection coil 3 is preferably located on the inner side of the excitation coil 4 and disposed on the outer peripheral surface of the columnar core portion 11.

  In the present invention, the first and second flat plate portions 12 and 13 are divided into two or more pieces 12A,... 13A, and an insulating layer is formed between the divided surfaces of the pieces 12A and 13A. It is characterized by being formed in a flat plate shape via the constituent material 14.

  The above-mentioned insulating layer constituting material 14 is composed of any of an epoxy resin, a polyimide resin, an aramid resin, a benzotriazole resin, a polyphenylene oxide resin, or a skeleton agent-containing resin obtained by adding a skeleton material to these resins. Is preferred. Here, a glass fiber, a glass nonwoven fabric, a resin fiber, a resin nonwoven fabric, etc. are employable as a frame | skeleton agent. By adopting these resins, each piece 12A, 13A can be reliably insulated from adjacent pieces. Moreover, these resin which comprises the insulating layer structural material 14 can enable adhesion | attachment of the division surfaces of an adjacent piece by heat welding. In particular, when a skeleton agent-containing resin containing a skeleton agent such as glass is employed, the strength at the joint portion can be improved.

  However, the insulating layer constituting material 14 preferably has a thickness of 3.0 mm or less. When the thickness of the insulating layer constituting material 14 exceeds 3.0 mm, soft magnetic materials such as permalloy, electromagnetic steel plate, soft ferrite, permender, pure iron, carbon steel for the entire first and second flat plate portions 12 and 13 This is because the ratio of the area occupied by the magnet is reduced and the magnetization efficiency of the cylindrical workpiece 2 by the exciting coil 4 is lowered.

  If the number of pieces constituting each of the flat plate portions 12 and 13 is two or more, it is possible to suppress eddy currents generated in the core targeted by the present invention. As the number of pieces to be configured increases, the eddy current generated in each piece decreases, and the eddy current generated in the entire core 10 can be suppressed.

  Moreover, it is preferable that each piece 12A, 13A cut | disconnects and cuts each flat plate part in the axial direction of the central axis 11C of the columnar core part 11. FIG. Note that the cut (divided) surfaces of the pieces 12A and 13A may be flat or curved. In this way, each piece 12A, 13A is configured by cutting in the axial direction of the central axis 11C of the columnar core 11, so that it can be divided along the direction of the magnetic flux generated by the exciting coil 4, and eddy currents can be divided. The suppression effect can be further improved.

  Furthermore, the arrangement of the pieces 12 </ b> A of the first flat plate portion 12 and the arrangement of the pieces 13 </ b> A of the second flat plate portion 13 are preferably mirror-symmetric with respect to the columnar core portion 11. Each insulating layer constituting material 14 portion of the first flat plate portion 12 and each insulating layer constituting material 14 portion of the second flat plate portion 13 appear in positions that are mirror-symmetric with respect to the columnar core portion 11. It is possible to suppress the eddy current generated in the core 10 while avoiding a decrease in the magnetization efficiency of the cylindrical workpiece 2 due to the exciting coil 4.

  And the external shape of the said 1st and 2nd flat plate parts 12 and 13 is the state with which each piece 12A or 13A and the insulating layer structural material 14 were combined, and the cross-sectional shape of the cylindrical workpiece 2 used as a measuring object. It is preferable that it is formed in a substantially similar shape.

  In the present embodiment, the cylindrical workpiece 2 to be measured has a substantially circular cross section. Therefore, each of the flat plate portions 12 and 13 has a central angle of 360 ° / n (n is an integer equal to or greater than 2) with the flat plate portions of the disk shape as the center point. It is preferable to divide into a plurality of fan-shaped pieces 12A,... 13A, and to have a substantially circular cross section through the insulating layer constituting material 14 between the divided surfaces of the pieces 12A, 13A. In FIG. 1, each flat plate portion is divided into four fan-shaped pieces so that the central angle is 90 ° (n = 4) with the plane center of the flat plate portion as a center point, and the divided surfaces of each piece are separated from each other. Insulating layer constituting material 14 is interposed between them to form a flat plate.

  In this way, by configuring the flat plate portion having a substantially circular cross section through the insulating layer constituting material 14 with the substantially identical fan-shaped pieces 12A or 13A, compared with the case of forming the flat plate portion from one flat plate, The eddy current generated in the piece 12A or 13A can be reduced on average. Therefore, the eddy current generated in the entire core 10 can be effectively suppressed.

  The first and second flat plate portions 12 and 13 are arranged inside the cylindrical workpiece 2, and the outer edges 12 </ b> E and 13 </ b> E of the flat plate portions 12 and 13 are the inner wall surfaces 21 of the cylindrical workpiece 2. And a dimension that can be arranged with a predetermined distance L apart. Here, the separation distance L between the outer edges 12E and 13E of the flat plate portions 12 and 13 and the inner wall surface 21 of the cylindrical workpiece 2 is a distance that can sufficiently magnetize the cylindrical workpiece 2 by the excitation coil 4. It is sufficient if a certain distance can be maintained.

  In the present embodiment, the inner wall surface 21 of the cylindrical workpiece 2 to be measured is tapered at a predetermined ratio so that the inner diameter S1 on one end side is larger than the inner diameter S2 on the other end side. Therefore, as shown in FIG. 2, the first and second flat plate portions 12 and 13 of the present embodiment include the center axis 11 </ b> C of the columnar core portion 11 and the plane centers 12 </ b> C and 13 </ b> C of the flat plate portions 12 and 13. In a state in which the virtual line X connecting the outer edge 12E of the first flat plate portion 12 and the outer edge 13E of the second flat plate portion 13 is disposed inside the cylindrical workpiece 2, The two inner wall surfaces 21 are formed so as to be substantially parallel with a predetermined distance L apart from the tapered shape.

  Therefore, in the quenching depth measurement probe 1 according to the present embodiment, even if the inner wall surface 21 of the cylindrical workpiece 2 to be measured is tapered at a predetermined ratio, the first flat plate portion 12 is used. It is possible to maintain a certain distance L between the outer edge 12E of the second flat plate portion 13 and the outer edge 13E of the second flat plate portion 13 and the inner wall surface 21 of the cylindrical workpiece 2. Therefore, it is possible to improve the measurement accuracy even for a workpiece in which a taper having a complicated shape is formed.

  In the above-described embodiment, the core 10 divides only the flat plate portions 12 and 13 into two or more pieces 12A, 13A, and between the divided surfaces of the pieces 12A and 13A. Although the structure which interposed the insulating layer structural material 14 is demonstrated, it is not limited to this. That is, in the above-described embodiment, the columnar core portion 11 constituting the core 10 is configured by a single member, but the columnar core portion 11 is also a cross section in the radial direction of the cylindrical workpiece 2 (columnar core portion). 11 is divided into n pieces 11A... Having a center angle of 360 ° / n (n is an integer of 2 or more). You may comprise integrally between the divided surfaces via the insulating-layer constituent material 14. The columnar core 11 is preferably divided into the pieces 11A at positions corresponding to the dividing surfaces of the pieces 12A and 13A of the first and second flat plate portions 12 and 13 described above. The division surface of each piece 11A of the columnar core portion 11 corresponds to the division surface of each piece 12A, 13A of the first and second flat plate portions 12, 13 in the axial direction of the central axis 11C of the columnar core portion 11. Accordingly, it is possible to suppress the eddy current generated in the core 10 while avoiding a decrease in the magnetization efficiency of the cylindrical workpiece 2 due to the exciting coil 4.

  Next, a quenching depth measurement method using the quenching depth measurement probe according to the present invention will be described. The quenching depth measurement method according to the present invention is a method performed in a production line for a cylindrical workpiece having a quench hardened layer. First, the quenching depth measurement probe 1 according to the present embodiment enters the cylindrical workpiece that has been heated and hardened on the inner wall surface in the production line using a high frequency induction heating method. Let them be placed. Specifically, the cylindrical workpiece 2 that has been quenched and disposed at a desired position is conveyed to a quenching depth measurement step by a conveying means provided in the production line, and the inside of the cylindrical workpiece 2 is Then, the quenching depth measuring probe 1 held by holding means (not shown) is inserted.

  In the present embodiment, as described above, the cylindrical workpiece 2 to be measured is tapered on the inner wall surface 21 at a predetermined ratio so that the inner diameter S1 on one end side is larger than the inner diameter S2 on the other end side. Since the tapered hub bearing is used, the quenching depth measurement probe 1 is inserted into the cylindrical workpiece 2 from the second flat plate portion 13 side whose outer dimension is smaller (smaller diameter) than the first flat plate portion 12. And place it at the position to be measured. At this time, the wiring of the detection coil 3 and the excitation coil 4 wound around the columnar core portion 11 of the core 10 has a larger outer dimension than the second flat plate portion 13 (large diameter) of the first flat plate portion 12. It is assumed that the wiring lead-out notch (opening) 12F formed at the end portion is drawn to the outside.

  The outer edges 12E and 13E of the first and second flat plate portions 12 and 13 are in contact with the inner wall surface 21 of the cylindrical workpiece 2 in a state where the quenching depth measurement probe 1 is installed inside the cylindrical workpiece 2. Are spaced apart by a distance L. In this state, a predetermined alternating current is applied to the exciting coil 4 to generate a magnetic field, and the inner wall surface 21 of the cylindrical workpiece 2 is magnetized. Thereby, an eddy current is generated on the inner wall surface 21 (surface) of the cylindrical workpiece 2. An induced electromotive force is generated by the eddy current generated on the inner wall surface 21 of the cylindrical workpiece 2, and the induced electromotive force acts on the detection coil 3.

  The detection coil 3 detects an induced magnetic field generated on the inner wall surface 21 of the cylindrical workpiece 2 magnetized by the excitation coil 4 and measures it as an output voltage of the detection coil 3. A voltmeter (not shown) is connected to the detection coil 3, and the output voltage of the detection coil 3 is measured.

  In this embodiment, the quenching depth measurement probe 1 specifies the depth of the hardened hardened layer on the inner wall surface 21 of the cylindrical workpiece 2 based on the measurement result of the output voltage of the detection coil 3. A depth specifying means is provided. The quenching depth specifying means is constituted by a general-purpose microcomputer, and includes a detected output voltage of the detection coil 3 and an estimated output voltage value included in known workpiece material information (electromagnetic characteristic information). Based on this, the depth of the hardened hardening layer is specified.

  Thereafter, the quenching depth measurement probe 1 held by a holding means (not shown) is retracted from the inside of the cylindrical workpiece. Thereby, in the production line of the cylindrical work provided with the hardened hardening layer, it becomes possible to inspect the entire amount of the depth of the hardened hardened layer of the tubular work 2 quickly and easily.

  Hereinafter, a method for obtaining an estimated output voltage value using known workpiece material information (electromagnetic characteristic information) will be described. In the present embodiment, for the same material as the material constituting the workpiece to be measured, the workpiece is obtained from the known electromagnetic property values of the non-quenched material that is not subjected to quenching and the fully quenched material that is subjected to quenching. The correlation between the quenching depth and the electromagnetic characteristic value of the material is analyzed and used as electromagnetic characteristic information. As the “known electromagnetic characteristic value” here, for example, a value disclosed in a document such as “Metal Handbook” edited by the Japan Institute of Metals is used as a physical property value specific to the material equivalent to the cylindrical workpiece 2. it can. That is, the known electromagnetic property value is a standard physical property value (conductivity σ, conductivity) of a non-hardened material (raw material) and a completely hardened material in a material equivalent to the material constituting the cylindrical workpiece 2 that is a measurement object. This is an estimated value of the output voltage that is expected to be detected by the detection coil 3 according to the quenching depth by an analysis method described later based on the permeability μ, the initial magnetization curve, and the like.

The following formulas (1) to (3) are used to derive the depth of the quench hardened layer. First, the magnetic flux density B (T) can be expressed by the following equation (1). The values of permeability μ and conductivity σ are different between the quenching material and the non-quenching material (raw material). Therefore, when the same applied magnetic field H as that of the workpiece is applied, the magnitude of the magnetic flux density B shown in Expression (1) differs depending on the difference between the completely quenched material and the non-quenched material (raw material).
B = μH (1)
In Equation (1), μ is the magnetic permeability, and H is the applied magnetic field (A / m).

Further, the eddy current Je (A / m ² ) can be expressed by the following formula (2). Although an eddy current is generated in an alternating magnetic field, the conductivity σ differs between a completely quenched material and a non-quenched material (raw material), and therefore, the value of the eddy current Je shown in Equation (2) is different between the two. And if the value of eddy current Je differs, magnetic flux density B will also change.
Je = −jσωφ (2)
In equation (2), j is the current density (A / m ² ), σ is the conductivity (S / m), ω is the angular frequency (ω = 2πf), and φ is the magnetic flux (Wb).

Next, the output voltage V (V) can be expressed by the following equation (3).
V = −N · dφ / dt (3)
In Equation (3), N is the number of coil turns, and t is time (s). The magnetic flux density B of the cylindrical workpiece 2 can be obtained from the equations (1) and (2). The output voltage V is obtained by using the magnetic flux density B obtained from the equations (1) and (2) and the equation (3).

  When a steel material is heated using a high frequency induction heating method and subjected to a quenching process, the magnetic permeability μ decreases. Moreover, when the quenching depth with respect to the cylindrical workpiece 2 is increased, the magnetic permeability μ of the entire inner wall surface 21 of the cylindrical workpiece 2 is decreased. If the change amount of the magnetic permeability μ with respect to the change amount of the quenching depth is linear, it can be calculated by an equivalent magnetization circuit, but is nonlinear. Therefore, numerical analysis using the Finite Element Method (FEM) is performed based on the permeability μ, conductivity σ, and initial magnetization curve of completely hardened material and non-hardened material (raw material). The output voltage V calculated for each quenching depth of the inner wall surface 21 of the cylindrical workpiece 2 was obtained, and this was used as the estimated power value expected to be detected by the detection coil 3.

  The quenching depth of the inner wall surface 21 of the cylindrical workpiece 2 included in the known electromagnetic characteristic information obtained as described above, and the output voltage of the inner wall surface 21 of the cylindrical workpiece 2 actually measured by the detection coil 3 are obtained. By comparison, the quenching depth of the cylindrical workpiece 2 can be specified.

  Note that the reliability of the estimated power value expected to be detected by the detection coil 3 obtained by performing numerical analysis by the finite element method (FEM) can be confirmed from the verification results shown below. The verification is performed by measuring the electromagnetic characteristic value according to the quenching depth using the test material and comparing it with the analysis value obtained by the numerical analysis described above.

  First, a method for measuring the electromagnetic property value of the test material will be described. Investigate the electromagnetic characteristics of non-quenched material (raw material) and fully-quenched material of the same material in advance, obtain the magnetization curves of non-quenched material (raw material) and fully-quenched material, and find the difference in electromagnetic property value To evaluate. A specific example of a method for acquiring known electromagnetic characteristic information will be given. First, prepare two cylindrical test materials that are the same material as the cylindrical workpiece to be measured. One is a non-quenched material (raw material) that is not hardened, and the other is hardened on the inner wall surface. Process to a fully quenched material. Then, the electromagnetic characteristics of these test materials are measured.

  For example, the conductivity σ was measured by connecting each test material to a Kelvin bridge circuit and measuring the magnetized test material. For the magnetic permeability μ, electromagnets were arranged at both ends of a long test material, and the magnetic flux density B and the applied magnetic field H of the test material magnetized by the electromagnet were measured. The magnetic flux density B was measured with a coil wound around the middle part of the test material. The applied magnetic field H was measured by placing a Hall element for measuring the applied magnetic field in the vicinity of the coil for measuring the magnetic flux density. From the measurement result of the magnetic permeability μ, initial magnetization curves of a completely quenched material and a non-quenched material (raw material) were obtained. A plurality of steel materials having different quenching depths were prepared, and the output voltage attenuation rate η and initial magnetization curve were obtained as electromagnetic characteristic values by the same method as described above.

  The relationship between the attenuation rate η of the output voltage and the quenching average depth of the test material obtained by the above method is shown in the graph of FIG. The attenuation rate η of the output voltage is expressed as a percentage of how much the output voltage is attenuated based on the output voltage obtained with the non-quenched material (raw material). FIG. 3 also shows the relationship between the analytical output voltage attenuation factor η obtained by the finite element method and the quenching depth. As shown in the graph of FIG. 3, the experimental value obtained by actually measuring the test material and the analytical value obtained by using the above-described analytical method were approximately approximated. Therefore, it can be said that the analysis method used in the above-described quenching depth measurement method can obtain highly reliable results.

  In the above-described production line, when the depth of the hardened hardened layer on the inner wall surface of the cylindrical workpiece 2 is measured using the quenching depth measurement probe 1 according to the present invention, the desired shape of the cylindrical workpiece 2 is determined. However, the present invention is not limited to this, and the cylindrical work is held by the holding means. The cylindrical workpiece 2 may be brought close to the quenching depth measurement probe 1 provided at a predetermined position by the holding means, and the quenching depth of the inner wall surface of the cylindrical workpiece 2 may be measured. .

  The quenching depth measurement probe 1 or the cylindrical workpiece 2 may be scanned in the axial direction of the cylindrical workpiece, and the quenching depth may be measured at a plurality of locations. In this case, the inner wall surface of the cylindrical workpiece 2 can be graphed by measuring the quenching depth at a plurality of locations, and the pattern of the quench hardened layer can be grasped.

  The quenching depth measurement probe according to the present invention is not limited to the configuration shown in FIG. 1, and the first and second flat plate portions are arranged at both ends of the columnar core portion, and the detection coil is provided at the columnar core portion. And the exciting coil, and at least the first and second flat plate portions may be configured such that a plurality of pieces and an insulating layer constituting material are interposed between the pieces.

  Next, examples and comparative examples using the quenching depth measurement probe according to the present invention will be described.

  The probe for quenching depth measurement of the embodiment measures the depth of the hardened hardened layer on the inner wall surface of the tapered hub bearing that is heated on the inner wall surface using a high frequency induction heating method. It is. The tapered hub bearing to be measured has an inner wall having a substantially circular cross section, and has an inner diameter S1 on one end side larger than an inner diameter S2 on the other end side. Therefore, in the quenching depth measurement probe of this example, the first and second flat plate portions are disk-shaped, and the outer diameter of the first flat plate portion is larger than the outer diameter of the second flat plate portion. Is formed. Each flat plate section has a virtual line connecting the outer edge of each flat plate section in the cross section including the center axis of the columnar core section and the plane center of each flat plate section. In this state, the taper hub bearing is formed so as to be substantially parallel to the tapered shape of the inner wall surface at a distance of 1.0 mm.

  In the quenching depth measurement probe of this embodiment, the core composed of the columnar core portion and the first and second flat plate portions are integrally formed of permalloy. The core is divided into four pieces while the first flat plate portion, the columnar core portion and the second flat plate portion are integrally formed, and each piece is insulated between the respective divided surfaces. They were assembled again by thermal welding with a layer constituent material interposed. Each piece was divided along the central axis of the columnar core portion so that the center angle was 90 ° with the plane center of each flat plate portion as the center point.

  The insulating layer constituent material interposed between the split surfaces of each piece employs an epoxy resin containing glass as a skeleton material, and the insulating layer constituent material has a thickness of 1.5 mm when the core is completed. So intervened. The insulating layer constituent material was bonded with an epoxy adhesive. As described above, a quenching depth measurement probe as an example was obtained.

Comparative example

  The quenching depth measurement probe as a comparative example differs from the quenching depth measurement probe as the above-described example only in that the core is not divided into pieces. Since other configurations are the same, description thereof is omitted.

  Here, FIG. 4 shows a relative permeability distribution by simulation when the inner wall surface of the tapered hub bearing to be measured is magnetized using the quenching depth measurement probe of the embodiment. FIG. 5 shows a magnetic flux density distribution by simulation when the inner wall surface of the tapered hub bearing to be measured is magnetized using the quenching depth measurement probe of the embodiment. 4 and 5, the right side shows the inner wall surface of the tapered hub bearing on which the hardened hardened layer is formed, and the left side shows the inner wall surface of the tapered hub bearing (untreated) in a state where the quenching treatment is not performed. Show. These simulations show a state in which an alternating current of 2 A 80 Hz is applied to the exciting coil. From the simulation results of FIGS. 4 and 5, it can be seen that the magnetic flux density is highly distributed on the inner wall surface that is not subjected to the quenching process with a high relative permeability.

  Next, FIG.6 and FIG.7 shows the heat_generation | fever simulation result of the probe for quenching depth measurement of an Example and a comparative example. Here, the current density and Joule loss generated in the core when energizing the excitation coil of the quenching depth measurement probe of the example and the comparative example will be examined.

FIG. 6 shows a simulation of the current density distribution on the core surface when the exciting coil is energized. The simulation shows a state in which an alternating current of 2 A 80 Hz is applied to the exciting coil. In the comparative example in which the core is not divided into a plurality of pieces, that is, composed of a single member, the outer peripheral surface of the columnar core portion around which the excitation coil is wound or the flat plate portion is joined to the columnar core portion. In the portion, the current density was 6.0 × 10 ⁵ A / m ² or more. Then, the current density of the inner surface of the flat plate portion on the side where the flat plate portions face each other gradually decreases from the columnar core portion to the outer edge portion, and the current density of the outer edge portion is 2.5 × 10 ⁵ A / m ^2. It was about. On the other hand, in the embodiment in which the core is divided into four pieces, and the insulating layer constituting material is interposed between the pieces, the outer peripheral surface of the columnar core portion around which the excitation coil is wound, and the flat plate portion Even at the junction with the columnar core, the current density was about 4.5 × 10 ⁵ A / m ² . And, the current density of the inner surface of the flat plate portion on the side where the flat plate portions face each other decreases from the columnar core portion to the outer edge portion, and the current density of the outer edge portion is about 1.0 × 10 ⁵ A / m ² . It had dropped to.

  FIG. 7 shows a simulation of Joule loss density distribution around the core surface when the exciting coil is energized. The simulation was performed when a 2 A 80 Hz alternating current was applied to the exciting coil. Further, as shown in the upper diagram of FIG. 7, the Joule loss density was simulated in the direction from the surface of the columnar core portion constituting the core toward the central axis.

In the case of the comparative example in which the core is not divided into a plurality of pieces, that is, composed of a single member, the Joule loss density on the surface of the columnar core is 160 kW / m ³ or more, and from the surface of the columnar core About 110 kW / m ³ at a depth of about 0.1 mm, about 40 kW / m ³ at a depth of about 0.5 mm from the surface of the columnar core, and about 10 kW / m at a depth of about 0.7 mm from the surface of the columnar core. m ³ approximately, was substantially zero at a depth of 1.1mm from the surface of the columnar core portions. On the other hand, in an example in which the core is divided into four pieces and the insulating layer constituent material is interposed between the pieces, the Joule loss density on the surface of the columnar core is about 70 kW / m ³ , Even when only the surfaces are compared, the Joule loss density is significantly smaller than that of the comparative example. Further, in the example, at a depth of about 0.1 mm from the surface of the columnar core, the Joule loss density is further reduced to about 35 kW / m ^3, and at a depth of about 0.3 mm from the surface of the columnar core. It was about 10 kW / m ³ . At a depth of about 0.7 mm from the surface of the columnar core, the Joule loss density was substantially zero.

  From the simulation results of FIG. 6 and FIG. 7, the current density on the surface of the columnar core can be greatly reduced by dividing the core into a plurality of pieces and interposing an insulating layer constituent material between the pieces. It can be seen that Joule heat loss near the surface of the columnar core can be greatly reduced.

  That is, as can be seen from the simulation results described above, the core itself is divided into two or more pieces as in the embodiment, and the core is formed through the insulating layer constituent material between the divided surfaces of each piece. It becomes possible to remarkably relieve the heat generation. Therefore, even if the quenching depth measurement probe is positioned inside the cylindrical workpiece close to the closed environment as described above, the heat generated from the core is trapped inside the cylindrical workpiece, and the core Abnormal heat generation can be prevented. Therefore, the quenching depth measurement probe of the present invention can effectively avoid overheating of the excitation coil and the detection coil wound around the columnar core portion of the core, and the insulating resin film of these coils is eluted. In addition, the occurrence of defects such as a short circuit can be prevented.

  This is because the eddy current generated in each piece is reduced by dividing at least the first and second flat plate portions constituting the core into two or more pieces and insulating each piece with an insulating layer constituting material. This is considered to be because the eddy current generated in the entire core could be remarkably suppressed.

  Generally, when an alternating current is applied to an exciting coil, a counter magnetic field is generated in a direction opposite to the magnetic field direction due to the eddy current due to the eddy current. When the counter magnetic field increases, the disturbance of the voltage waveform detected by the detection coil increases. As described above, according to the present invention, the eddy current generated in the core can be remarkably suppressed, so that the repulsive magnetic field can be reduced, and the disturbance of the voltage waveform detected by the detection coil is suppressed. it can. As a result, the accuracy of the output voltage detected by the detection coil can be increased, and the depth of the hardened and hardened layer can be accurately measured.

  Further, as described above, the present invention can alleviate the heat generation of the core itself. Therefore, even if the measurement probe is placed inside the cylindrical workpiece and the measurement is performed, the core, the detection coil, and the workpiece The temperature rise can be effectively suppressed and fluctuations in electrical and magnetic characteristics can be minimized, so that the depth of the hardened layer can be measured with high accuracy based on the output voltage of the detection coil. It becomes possible.

  In addition, the quenching depth measurement method performed in the manufacturing line of the cylindrical workpiece | work provided with the quenching hardened layer mentioned above is not limited to the above-mentioned method, For quenching depth measurement inside a cylindrical workpiece. After the probe is placed and magnetized, the cylindrical workpiece is magnetized, the depth of the hardened hardened layer of the cylindrical workpiece is specified based on the output voltage detected by the detection coil, and then the quenching depth measurement probe Any method may be used as long as it is a method capable of retracting from the inside of the cylindrical workpiece.

  The quenching depth measurement probe according to the present invention suppresses the temperature rise of the yoke, coil, workpiece, etc., even when measuring the depth of the hardened hardened layer on the inner wall surface of the cylindrical workpiece. The depth of the hardened and hardened layer can be measured safely and with high accuracy by the method using destruction. Moreover, the quenching depth measurement probe according to the present invention is suitable for performing a full inspection on the depth of the hardened hardened layer in the manufacturing process.

DESCRIPTION OF SYMBOLS 1 Hardening depth measurement probe 2 Workpiece 3 Detection coil 4 Excitation coil 10 Core 11 Columnar core part 11A, 11B End part 11C Center axis 12, 13 1st, 2nd flat plate part 12A, 13A Piece 12C, 13C Plane center 12E, 13E Outer edge 14 Insulating layer constituent material 21 Inner wall surface S1, S2 Opening dimension (inner diameter) of cylindrical workpiece
L Distance between the inner wall surface of the cylindrical workpiece and the end of the flat plate part X Virtual line

Claims (9)

A quenching depth measurement probe for measuring the quenching depth of the inner wall surface of the cylindrical workpiece disposed inside the cylindrical workpiece,
Dividing each piece divided into two or more pieces by arranging a first flat plate portion with an insulating layer constituting material interposed between the divided surfaces of each piece divided into two or more pieces at one end of the columnar core portion A core in which a second flat plate portion formed by interposing an insulating layer constituent material between the surfaces is arranged in parallel to the first flat plate portion at the other end of the columnar core portion;
Is wound on the outer periphery of the columnar core portion of the core, an excitation coil magnetizing the cylindrical workpiece,
A detection coil that is wound around the outer periphery of the columnar core of the core and detects an induced magnetic field generated by the magnetization;
A quenching depth specifying means for specifying the quenching depth of the cylindrical workpiece from the output voltage measured by detecting the induction magnetic field of the detection coil and known electromagnetic property information on the equivalent material to the cylindrical workpiece; Prepared,
The quenching depth specifying means is a detection obtained by using an initial magnetization curve and conductivity, which are standard physical property values unique to a non-quenched material that is not quenched and a completely quenched material that is quenched. A quenching depth measurement probe characterized by identifying a quenching depth of the cylindrical workpiece from known electromagnetic characteristic information including an estimated voltage value of a coil and an output voltage of a detection coil .   Each piece of said 1st and 2nd flat plate part is what divided | segmented the center angle | corner centering on the plane center of each flat plate part by 360 degrees / n (n is an integer greater than or equal to 2). The probe for quenching depth measurement as described.   The quenching depth measurement probe according to claim 1 or 2, wherein each flat plate portion has a plane center of each flat plate portion arranged on an extension line of a central axis of the columnar core portion.   The columnar core portion has a central angle of 360 ° / n (n is a center point) at the center in the radial cross section of the cylindrical workpiece at a position corresponding to the dividing surface of the first and second flat plate portions. The probe for quenching depth measurement according to claim 2 or 3, wherein the probe is divided into n pieces (an integer of 2 or more) and an insulating layer constituting material is provided between the divided surfaces of the pieces. .   The probe for quenching depth measurement according to any one of claims 1 to 4, wherein the detection coil is positioned inside the excitation coil and wound around an outer peripheral surface of the columnar core portion.   The probe for quenching depth measurement according to any one of claims 1 to 5, wherein the insulating layer constituting material has a thickness of 3.0 mm or less.   The insulating layer constituting material is constituted by any one of an epoxy resin, a polyimide resin, an aramid resin, a benzotriazole resin, a polyphenylene oxide resin, or a skeleton agent-containing resin obtained by adding a skeleton material to these resins. The probe for quenching depth measurement according to claim 6. A quenching depth measurement probe for measuring a quenching depth of the cylindrical workpiece having a tapered shape on an inner wall surface,
In a cross section including the central axis of the columnar core portion constituting the core and the center of each flat plate portion, an imaginary line connecting the outer edge of the first flat plate portion and the outer edge of the second flat plate portion is the core. The quenching depth according to any one of claims 1 to 7, wherein the quenching depth is formed so as to be substantially parallel to a tapered shape of an inner wall surface of the cylindrical workpiece in a state of being disposed inside the cylindrical workpiece. Probe for measurement. A quenching depth measurement method performed in a production line of a cylindrical workpiece having a quench hardened layer,
The quenching depth measurement probe according to any one of claims 1 to 8 is caused to enter the inside of a cylindrical workpiece that has been heated and hardened with respect to the inner wall surface using a high-frequency induction heating method. Place and
The cylindrical workpiece is magnetized by the excitation coil of the quenching depth measurement probe,
After detecting the induction magnetic field generated by magnetization with a detection coil and specifying the depth of the hardened and hardened layer of the cylindrical workpiece based on the output voltage detected with the detection coil,
A quenching depth measurement method performed in a production line for a cylindrical workpiece having a quench hardened layer, wherein the quenching depth measurement probe is retracted from the inside of the cylindrical workpiece.