JP2011252787A - Hardening quality inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardening quality inspection device capable of easily and accurately inspect hardening quality of an inspection object by removing effects of residual magnetism in the inspection object and using non-destructive inspection.SOLUTION: The hardening quality inspection device is provided with electrodes 2, 2 for conduction to be brought into contact with the surface of an inspection object 1, a power supply 4, and a magnetic field detection means 5 that measures a magnetic field generated by a quality measurement current flowing through the inspection object 1. It is provided with a quality measurement means 18 that measures hardening quality of the inspection object 1 based on the magnetic field measured by the magnetic field detection means 5, and with a demagnetization means 7A that demagnetizes a residual magnetism in the inspection object 1 before quality measurement.

Description

  The present invention relates to a quenching quality inspection apparatus for inspecting quenching quality such as quenching hardness distribution and quenching depth in steel products.

  Quenching and tempering treatments are applied to rolling products such as bearings. Among these treatments, in the surface hardening treatment such as induction hardening treatment, carburizing treatment, carbonitriding treatment, etc., the surface hardened layer is inspected for quality assurance. In this inspection, an actual product is cut and the depth of the cured layer is measured by measuring the hardness in the depth direction from the product surface on the cut surface. If the product cannot be cut, heat-treat the test piece in the same furnace as the product, cut the test piece, measure the cured layer depth in the same way as above, and guarantee the cured layer depth of the product. Yes.

In this way, in the inspection of the depth of the hardened layer of the heat-treated rolling product, a destructive inspection for cutting the product is performed. In this case, the product is destroyed, which increases the material cost. is there. In addition, there is a problem that it takes time to cut the product and to measure the hardness in the depth direction using a hardness meter, which increases the number of steps.
If the product cannot be cut, it is guaranteed by the test piece as described above. However, since it is not an actual product inspection, there are problems such as poor guarantee accuracy.

  Therefore, in order to solve the above-described problems in the destructive inspection, a method for inspecting the hardened hardened layer in a nondestructive manner has been proposed. One example of the proposed non-destructive inspection is a potential difference method in which inspection is performed by utilizing a change in conductivity due to quenching. This method uses a probe that is in contact with an inspection object, and a direct current is passed through the inspection object to measure the potential difference between two probes that are in contact with the inspection object at a position different from the contact position of the probe. Thus, the quenching depth is obtained (for example, Patent Documents 1 and 2).

JP 2004-309355 A JP 2007-064817 A Japanese Patent Application No. 2009-134727

  In the non-destructive inspection method described above, since a direct current is applied to the inspection object, the hardness distribution in the depth direction cannot be measured although it is effective for measuring the quenching depth. In order to improve the quality assurance accuracy of quenching, it is necessary to detect not only the quenching depth but also the distribution of quenching hardness in the depth direction.

  In order to solve the above problem, as shown in FIG. 5, the applicant forms a detection head 28 integrally including a pair of energizing electrodes 22 and 22 and a magnetic field sensor 25 that measures a magnetic field, and the inspection object 21. The current-carrying electrodes 22, 22 are brought into contact with the surface of the current, and a current is passed from the power source through the current-carrying electrodes 22, 22 to the inspection object 21. A quenching quality inspection device for inspecting quenching depth and quenching hardness distribution by measuring was proposed (Patent Document 3). In this apparatus, since the depth at which the current flows can be controlled by changing the frequency of the current, the hardness distribution in the depth direction can be detected.

  By the way, in a polishing process in manufacturing a mechanical part such as a bearing, a magnet chuck or the like is used to hold the mechanical part, and thus magnetism may remain in the manufactured mechanical part. If the quenching hardened layer depth is inspected with the above-described quenching quality inspection apparatus using such mechanical parts having magnetism as inspection objects, there is a problem that the inspection accuracy deteriorates due to residual magnetism. In this case, if the magnetism remaining in the machine part is demagnetized in advance using a demagnetizer and then inspected by a quenching quality inspection device, the above-described problems can be solved. . However, in order to do so, it is necessary to prepare a demagnetizer separately from the quenching quality inspection apparatus, which causes a new problem that the quenching quality inspection process becomes complicated.

  An object of the present invention is to provide a quenching quality inspection apparatus that can easily and accurately inspect the quenching quality of an inspection object by non-destructive inspection without the influence of magnetism remaining on the inspection object. .

  The quenching quality inspection apparatus according to the present invention is a quenching quality inspection apparatus for inspecting quenching quality by passing a current through an inspection object and measuring a magnetic field generated by a current flowing through the inspection object, the inspection object An energizing electrode to be brought into contact with the surface of the object, a power source for applying a current for quality measurement to the inspection object via the energizing electrode, and a quality measuring current flowing through the inspection object by the power source are generated. Magnetic field detection means for measuring a magnetic field, quality measurement means for measuring the quenching quality of the inspection object, and magnetic field remaining on the inspection object before the quality measurement are demagnetized by the magnetic field measured by the magnetic field detection means. And a demagnetizing means.

According to this configuration, the pair of energization electrodes are brought into contact with the surface of the inspection object, and a current for quality measurement is applied from the power source through the energization electrodes. In this state, the magnetic field generated by the current flowing through the inspection object is measured by the magnetic field detection means. The quality measuring means measures the quenching quality of the inspection object by the magnetic field measured by the magnetic field detecting means. For example, a change in the magnetic path cross-sectional area of the magnetic field appears as a change in magnetic resistance, and quenching quality such as quenching hardness and quenching depth of the inspection object is obtained from the change in magnetic field based on the change in magnetoresistance.
The permeability and conductivity of the steel material change due to quenching. Generally, the higher the hardness of a steel material by quenching, the smaller the permeability and conductivity. For this reason, the current flowing through the inspection object varies depending on the quenching hardness and depth. Therefore, the change in the current is detected by measuring the change in the magnetic field caused by the change in the magnetic path cross-sectional area of the magnetic field generated by the current with the magnetic field detection means.

The depth at which current flows through the inspection object 1 varies depending on the frequency f, conductivity σ, and permeability μ due to the skin effect. Here, the depth δ through which the current flows is expressed by the following equation (1).
δ = √ (1 / πfσμ) (1)
From the above equation (1), the penetration depth at which current flows through the inspection object 1 varies depending on the frequency. For this reason, by changing the frequency, the measurement can be performed while changing the depth at which the current flows. For example, when a high frequency current is applied, the current can flow only on the surface of the inspection object, so that the quenching hardness of the surface of the inspection object can be known. As the frequency is gradually decreased from the high frequency side, the penetration depth of the current increases. Therefore, for example, the distribution of the quenching hardness in the depth direction can be estimated by measuring the magnetic field while decreasing the frequency from the high frequency side. Thus, the quenching quality of the inspection object can be accurately inspected by nondestructive inspection.
In particular, since the demagnetizing means is provided to demagnetize the magnetism remaining on the inspection object before quality measurement, the influence of the magnetism remaining on the inspection object is eliminated without providing a separate demagnetizer. The quenching quality of the inspection object can be easily and accurately inspected by nondestructive inspection.

  In the present invention, the demagnetization means may be a demagnetization current supply unit that is provided in the power source and applies a demagnetization current to the inspection object via the energization electrode before quality measurement. good. In the case of this configuration, since most of the configuration of the power source and the energization electrode can be shared as demagnetizing means, the configuration can be simplified.

  In the present invention, the demagnetizing current is preferably an alternating current whose amplitude gradually decreases, and the alternating current is preferably of a constant period.

In the present invention, the quality measuring current is preferably an alternating current having a constant amplitude and a varying frequency.
If the current for quality measurement applied from the power source to the inspection object is an alternating current with a constant amplitude and frequency, the quenching quality for inspection purposes can be determined according to the frequency, and various quality inspections can be performed. It can be carried out. The change in the frequency of the quality measurement current may be gradually changed or may be changed step by step.

  In the present invention, the magnetic field detecting means is preferably a magnetic field sensor capable of measuring a low frequency magnetic field. The lower the frequency of the alternating current applied to the inspection object, the more the alternating current flows in the deeper part of the inspection object. Therefore, in order to know the quenching hardness at a deeper position, the magnetic field sensor uses a low-frequency magnetic field. What can be measured is desirable.

  In the present invention, the magnetic field sensor may be any one of a Hall sensor, an MR sensor, a GMR sensor, a TMR sensor, an MI sensor, and a fluxgate sensor.

  In the present invention, the quality measuring means may measure at least one of the surface hardness, the quenching hardness distribution in the depth direction, and the quenching depth of the inspection object as the quenching quality.

  The quenching quality inspection apparatus according to the present invention is a quenching quality inspection apparatus for inspecting quenching quality by passing a current through an inspection object and measuring a magnetic field generated by a current flowing through the inspection object, the inspection object An energizing electrode to be brought into contact with the surface of the object, a power source for applying a current for quality measurement to the inspection object via the energizing electrode, and a quality measuring current flowing through the inspection object by the power source are generated. Magnetic field detection means for measuring a magnetic field, quality measurement means for measuring the quenching quality of the inspection object, and magnetic field remaining on the inspection object before the quality measurement are demagnetized by the magnetic field measured by the magnetic field detection means. Since the demagnetizing means is provided, the quenching quality of the inspection object can be easily and accurately inspected by nondestructive inspection without the influence of magnetism remaining on the inspection object.

It is explanatory drawing which shows the outline | summary of the quenching quality inspection apparatus concerning one Embodiment of this invention. It is a block diagram which shows the structure of the quenching quality inspection apparatus. It is a wave form diagram of the current for quality measurement which the power supply of the quenching quality inspection apparatus supplies. It is a wave form diagram of the current for demagnetization which the demagnetizing means of the quenching quality inspection apparatus supplies. It is a block diagram which shows the structure of a proposal example.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the principle of the quenching quality inspection apparatus of this embodiment will be described. In this quenching quality inspection apparatus, a current for quality measurement is applied to the inspection object 1, and the quenching quality is inspected by measuring the magnetic field 6 generated by the current 3 flowing through the inspection object 1. In the figure, the magnetic field 6 is indicated by a line indicating a magnetic flux, and the current 3 is indicated by a line indicating a flow path. The inspection object 1 is a steel product such as a part subjected to quenching treatment, such as a bearing or a bearing part. However, it is not limited to these steel products.

In this example, an alternating current is used as an energizing current for quality measurement. As shown in FIG. 1, the AC current for quality measurement is supplied, that is, applied from a power source 4 that is an AC power source via a pair of energizing electrodes 2 and 2 that are in contact with the inspection object 1. An alternating current is applied to the inspection object 1, and the magnetic field 6 generated by the current 3 flowing through the inspection object 1 is measured by the magnetic field sensor 5 that is a magnetic field detection means provided on the inspection object 1. The magnetic field sensor 5 is a sensor that detects the strength or magnitude and direction of the magnetic field, and outputs the voltage value, for example. The “magnetic field sensor” referred to in this specification includes a magnetic sensor.
The steel material to be inspected 1 changes its magnetic permeability and conductivity by quenching. Generally, the higher the hardness of a steel material by quenching, the smaller the permeability and conductivity. For this reason, the current flowing through the inspection object 1 varies depending on the quenching hardness and depth. Therefore, the change in current is detected by measuring the strength or magnitude of the magnetic field generated by the current with the magnetic field sensor 5.

The depth at which current flows through the inspection object 1 varies depending on the frequency f, conductivity σ, and permeability μ due to the skin effect. Here, the depth δ through which the current flows is expressed by the following equation (1).
δ = √ (1 / πfσμ) (1)
From the above equation (1), the penetration depth δ through which the current flows through the inspection object 1 varies with the frequency f. Therefore, by changing the frequency f, it is possible to perform measurement while changing the depth δ through which the current flows. For example, when a high frequency current is applied, the current can flow only on the surface of the inspection object, so that the quenching hardness of the surface of the inspection object can be known. From this viewpoint, in order to know the quenching hardness at a deeper position, it is desirable that the magnetic field sensor 5 can measure a low-frequency magnetic field. As the frequency is gradually decreased from the high frequency side, the current penetration depth δ increases. Therefore, for example, the distribution of the quenching hardness in the depth direction can be estimated by measuring the magnetic field while decreasing the frequency f from the high frequency side. Thus, the quenching quality of the inspection object 1 can be accurately inspected by nondestructive inspection. When changing the frequency f, it may be changed stepwise or continuously.

  FIG. 2 shows the configuration of the quenching quality inspection apparatus. This quenching quality inspection apparatus includes a probe 8 serving as a detection head and a measurement apparatus 9. The probe 8 includes a pair of energizing electrodes 2 and 2 that are brought into contact with the surface 1a of the inspection object 1 and a magnetic field sensor 5 that measures a magnetic field generated by a quality measurement current flowing through the inspection object 1 by the power source 4. It is one. That is, the magnetic field sensor 5 is mounted on the sensor substrate 11 and fixed to the sensor housing 13 with the molding material 12 or the like. The sensor housing 13 is preferably a non-magnetic material such as resin. In the illustrated example, the sensor housing 13 is formed in a block shape, and has a shape in which a peripheral wall protrudes from the outer periphery of the lower surface, and an inner portion of the peripheral wall becomes a recessed portion, and a sensor substrate is formed on the bottom surface of the recessed portion. 11 is arranged. The molding material 12 fills a gap between the sensor substrate 11 on which the magnetic field sensor 5 is mounted and the peripheral wall of the sensor housing 13.

  The sensor housing 13 is fixed with electrodes 14 and 15 which are wirings to the sensor substrate 11 and the pair of energizing electrodes 2 and 2. Each energizing electrode 2 is formed in a round bar shape, and at least one end of the energizing electrode 2 is arranged on the probe 8 from the top to the bottom so as to protrude from the end face of the sensor housing 13. The electrodes 14 and 15 and the energizing electrode 2 are inserted through through holes provided in the sensor housing 13. The pair of energization electrodes 2 and 2 are arranged in parallel at a predetermined distance, and the magnetic field sensor 5 is arranged between the energization electrodes 2 and 2. The other end of each energizing electrode 2 is electrically connected to an amplifier circuit 16 (described later) in the measuring device 9, and electrodes 14 and 15 fixed to the sensor substrate 11 are connected to a sensor signal processing circuit 17 (described later) in the measuring device 9. Is electrically connected.

In FIG. 2, the measuring device 9 has a power source 4 and quality measuring means 18. The power supply 4 includes a frequency variable oscillation circuit 19 and an amplification circuit 16 that amplifies an AC signal output from the oscillation circuit 19 and supplies, that is, applies a current to be supplied to the inspection object 1. The oscillation circuit 19 is electrically connected to the signal processing unit 20 of the quality measuring unit 18 and changes the frequency according to an instruction from the signal processing unit 20.
The quality measuring means 18 measures the quenching quality of the inspection object 1 by the magnetic field measured by the magnetic field sensor 5 while changing the frequency of the quality measuring alternating current output from the oscillation circuit 19. Here, the AC current for quality measurement has a waveform in which the amplitude is constant and the frequency is gradually changed as shown in FIG. The change in frequency may occur in stages. The quality measuring means 18 includes a sensor signal processing circuit 17 that performs preprocessing such as amplification, linearization, and filter processing on the signal of the magnetic field sensor 5, and the quenching depth and the like from the magnetic field sensor signal preprocessed by the sensor signal processing circuit 17. And a signal processing unit 20 for estimating the hardness distribution.

  The signal processing unit 20 is a means for estimating the surface hardness, the quenching hardness distribution in the depth direction, and the quenching depth (referred to as “quenching hardness etc.”) of the inspection object 1 as the quenching quality. The signal processing unit 20 uses the detected voltage value as a voltage value and a quality value (surface hardness, quenching hardness distribution in the depth direction, quenching depth) corresponding to the amount of change in magnetic resistance determined for each of these quality items. Etc.), the corresponding surface hardness, quenching hardness distribution in the depth direction, quenching depth, etc. are output as estimated values. However, it is also possible to measure at least one of the surface hardness, the quenching hardness distribution in the depth direction, and the quenching depth of the inspection object 1. The signal processing unit 20 includes a determination unit 20a and a frequency change command unit 20b. The determination unit 20a performs the above estimation and the next abnormality determination.

The determination unit 20a determines that the quality abnormality, that is, the quenching abnormality, when the quenching quality estimated as described above from the measurement value is lower than the set quality value. The determination unit 20a includes an electronic circuit that calculates a quenching hardness in the depth direction that is proportional to the signal processed by the sensor signal processing circuit 17, and an electronic circuit that performs abnormality determination. The electronic circuit for calculating the quenching hardness and the like of the determination unit 20a has a relationship setting means (not shown) in which the relationship between the detected voltage value and the quenching hardness in the depth direction is set by an arithmetic expression or a table. Then, a voltage value, which is a signal based on the intensity or magnitude and direction of the measured magnetic field, is compared with the relationship setting means to calculate the quenching hardness in the depth direction.
The set quality value is a threshold that is appropriately set by obtaining from various tests and is stored in, for example, a rewritable storage medium (not shown). As the abnormality determination, the determination unit 20a determines whether or not the quenching hardness of an arbitrary depth calculated in light of the relationship setting unit is below a set quality value at the same depth. When the calculated quenching hardness is lower than the set quality value, it is determined that the quality is abnormal.

  The frequency change command unit 20 b gives a command to continuously change the frequency of the AC signal to the oscillation circuit 19 of the AC power supply 4. In response to the command from the frequency change command unit 20b, the frequency of the AC signal output from the oscillation circuit 19 sequentially changes as shown in FIG. Here, the frequency change command unit 20b variably sets only the frequency of the AC signal of the oscillation circuit 19 serving as the quality measurement current. However, the amplitude may be variably set in addition to the frequency. Further, the frequency change command unit 20b has, for example, a plurality of types of rules such as change width, frequency, change repetition period, etc. for changing the frequency according to the type of the desired quenching quality, the type of the inspection object 1, and the like. It may be set and an arbitrary rule can be selected by appropriate input. As a specific example, the alternating current is changed between, for example, 10 Hz to 10 kHz while inspecting one inspection object.

  The frequency change command unit 20 b gives a command to change the frequency to the oscillation circuit 19 at the same location of the inspection object 1. As a result, the penetration depth at which current flows through the inspection object 1 changes. In this case, the determination unit 20a calculates the quenching hardness of each depth by illuminating the signal based on the measured magnetic field strength or magnitude and direction with the relation setting means. By repeating such frequency change, the determination unit 20a can estimate the distribution of the quenching hardness in the depth direction. Note that the determination unit 20a may temporarily store signals based on the strength or magnitude and direction of the magnetic field at a plurality of frequencies, and estimate the distribution of the quenching hardness in the depth direction.

  The measuring device 9 is provided with a demagnetizing current supply unit 7A for applying a demagnetizing current to the inspection object 1 before quality measurement. The demagnetizing current supply unit 7A is provided in the power source 4. The demagnetization current supplied from the demagnetization current supply unit 7A is applied to the inspection object 1 through the energization electrodes 2 and 2, and thereby the magnetism remaining on the inspection object 1 is measured before quality measurement. Demagnetized. That is, the demagnetizing current supply unit 7A and the energizing electrodes 2 and 2 constitute demagnetizing means for demagnetizing the magnetism remaining on the inspection object 1 before quality measurement.

The demagnetizing current supply unit 7 </ b> A in the power supply 4 includes a mode selection unit 10, an oscillation circuit 19, and an amplification circuit 16. The oscillation circuit 19 and the amplifier circuit 16 that constitute a part of the demagnetization current supply unit 7A are shared with the quality measurement current supply unit 7B. The mode selection unit 10 receives a selection command from an external switch or the like before quality measurement, and causes the oscillation circuit 19 to change its AC signal to a signal waveform whose amplitude gradually decreases at a constant frequency, for example, as shown in FIG. Control to be. That is, the demagnetizing current applied to the inspection object 1 from the demagnetizing current supply unit 7A via the energization electrodes 2 and 2 is an alternating current whose amplitude gradually decreases at a constant frequency. The change in the amplitude is changed from the amplitude at which the maximum current is applied as a demagnetizing current to zero while demagnetizing one inspection object, for example. When the selection command is not input to the mode selection unit 10 from the outside, only the quality measurement current supply unit 7B in the power source 4 operates, and the AC current for quality measurement in the waveform diagram as shown in FIG. It is applied to the inspection object 1 through the energization electrodes 2 and 2.
Further, before performing the measurement, a demagnetization may be performed by giving a command to change only the amplitude with a constant frequency from the frequency change command unit 20b to the demagnetization current supply unit 7A. In this case, the mode selection unit 10 can be omitted.

  Thus, in this quenching quality inspection apparatus, the current-carrying electrodes 2 and 2 are brought into contact with the surface of the inspection object 1, and a quality measurement current is supplied to the inspection object 1 from the power supply 4 via the current-carrying electrodes 2 and 2. The magnetic field generated by the current flowing through the inspection object 1 at this time is measured by the magnetic field sensor 5 as the magnetic field detection means, and the quenching quality of the inspection object 1 is measured by the quality measurement means 18 by the magnetic field measured by the magnetic field sensor 5. Therefore, the quenching quality of the inspection object 1 can be inspected with high accuracy by nondestructive inspection.

  In particular, a demagnetizing current supply unit 7A serving as a demagnetizing means is provided in the power source 4 of the measuring device 9 so as to demagnetize the magnetism remaining on the inspection object 1 before quality measurement. Without using a machine, the influence of magnetism remaining on the inspection object 1 can be eliminated, and the quenching quality of the inspection object 1 can be inspected easily and accurately by nondestructive inspection. Further, since it is not necessary to provide a demagnetizing coil in the probe 8 serving as the detection head, the structure of the probe 8 can be simplified and downsized.

  Further, in this embodiment, the current for demagnetization is an alternating current whose amplitude gradually decreases, and the period of the alternating current is a constant period, so that it is more effective to demagnetize the residual magnetism of the inspection object 1. Can be raised.

  In this embodiment, the quality measuring means 18 has a frequency change command unit 20b that changes the frequency output from the AC power supply in various ways, and measures the magnetic field at each frequency changed by the frequency change command unit 20b. In addition, since it has a function of measuring the quenching quality, it is easy to change the frequency suitable for obtaining the quenching quality to be inspected.

  In this embodiment, an alternating current whose frequency sequentially changes is used as the quality measurement current. However, it is also possible to use a single frequency alternating current that does not change the frequency. Further, a direct current may be used as the quality current. In this case, currents with different directions and magnitudes may be applied to the inspection object 1 to measure the strength or magnitude and direction of the magnetic field for each current with different directions and magnitudes. Also in this case, the quenching depth of the inspection object 1 can be measured in the same manner as in the above embodiment.

  The magnetic field sensor 5 used as the magnetic field detection means in the above embodiment includes a magnetic impedance element (MI sensor, MI: Magneto-Impedance), a magnetoresistive element (MR sensor, MR: Magnetoresistive), a giant magnetoresistive element (GMR sensor, GMR: Giant Magnetoresisitive), tunnel magnetoresistive element (TMR sensor, TMR: Tunnel Magnetoresisitive), Hall sensor, fluxgate sensor, etc. can be used. When measuring only an alternating magnetic field, a wound magnetic field sensor may be used.

DESCRIPTION OF SYMBOLS 1 ... Test object 2 ... Electrode 4 for energization ... Power supply 5 ... Magnetic field sensor (magnetic field detection means)
7A ... Current supply section for demagnetization (demagnetization means)
18 ... Quality measuring means 20b ... Frequency change command section

Claims (8)

A quenching quality inspection device that inspects the quenching quality by passing a current through the inspection object and measuring the magnetic field generated by the current flowing through the inspection object,
An energization electrode that is brought into contact with the surface of the inspection object, a power source that applies a current for quality measurement to the inspection object via the energization electrode, and a quality measurement current that flows through the inspection object by the power source Magnetic field detection means for measuring the magnetic field generated by the magnetic field, quality measurement means for measuring the quenching quality of the inspection object by the magnetic field measured by the magnetic field detection means, and magnetism remaining on the inspection object before the quality measurement A quenching quality inspection apparatus comprising a demagnetizing means for demagnetizing.   2. The quenching according to claim 1, wherein the demagnetizing means is a demagnetizing current supply unit that is provided in the power source and applies a demagnetizing current to the inspection object via the energization electrode before quality measurement. Quality inspection device.   3. The quenching quality inspection apparatus according to claim 2, wherein the demagnetizing current is an alternating current whose amplitude gradually decreases.   4. The quenching quality inspection apparatus according to claim 3, wherein the demagnetizing current is an alternating current having a constant period.   5. The quenching quality inspection apparatus according to claim 1, wherein the quality measurement current is an alternating current having a constant amplitude and a varying frequency.   6. The quenching quality inspection apparatus according to claim 1, wherein the magnetic field detection unit is a magnetic field sensor capable of measuring a low-frequency magnetic field.   The quenching quality inspection apparatus according to claim 6, wherein the magnetic field sensor is any one of a Hall sensor, an MR sensor, a GMR sensor, a TMR sensor, an MI sensor, and a fluxgate sensor.   The quality measuring means according to any one of claims 1 to 7, wherein the quality measuring means includes at least one of a surface hardness, a quenching hardness distribution in a depth direction, and a quenching depth of the inspection object as the quenching quality. Quenching quality inspection device to measure.

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