JP2011257223A - Hardening quality inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardening quality inspection device which is capable of accurately inspecting hardening quality of an object to be inspected, by nondestructive inspection.SOLUTION: The hardening quality inspection device includes: current-carrying electrodes 2 and 2 to be brought into contact with a surface of an object 1 to be inspected; a power source 4; magnetic field detection means 5 for measuring a magnetic field generated by a current flowing in the object 1 to be inspected; quality measuring means 18 for measuring hardening quality of the object 1 to be inspected, by the magnetic field measured by the magnetic field detection means 5; and disturbance magnetic field removal means 7 for preventing the influence of a magnetic field generated by a current flowing outside the object to be inspected, on measurement of the magnetic field detection means 5.

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. 8, the applicant of the present invention applies a current to the inspection object 21 and measures the magnetic field generated by the current flowing through the inspection object 21 to thereby reduce the quenching depth and the hardness. A quenching quality inspection device for inspecting distribution and the like has been 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. However, in this apparatus, the energization electrodes 22 and 22 for energizing the current and the magnetic field sensor 25 for measuring the magnetic field are integrated to form the detection head 28, and the current is energized from the upper side to the lower side in the detection head 28. Thus, since the energizing electrodes 22 and 22 are arranged, there is a problem that the detection accuracy deteriorates due to the influence of the current flowing through the energizing electrodes 22 and 22 by the magnetic field that is the measurement target of the magnetic field sensor 25. .

  An object of the present invention is to provide a quenching quality inspection apparatus capable of accurately inspecting the quenching quality of an inspection object by nondestructive inspection.

  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 A current-carrying electrode brought into contact with the surface of the object, a power source for applying a current to the inspection object via the current-carrying electrode, and a magnetic field detection means for measuring a magnetic field generated by a current flowing through the inspection object by the power source And the quality measuring means for measuring the quenching quality of the inspection object by the magnetic field measured by the magnetic field detection means, and the magnetic field generated by the current flowing outside the inspection object affects the measurement of the magnetic field detection means. Disturbing magnetic field removing means for preventing application is provided.

According to this configuration, the pair of energization electrodes are brought into contact with the surface of the inspection object, and a current 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, a disturbance magnetic field removing means is provided to prevent the disturbance magnetic field generated by the current flowing outside the inspection object from affecting the measurement of the magnetic field detection means. The quality of quenching can be inspected with higher accuracy.

  In this invention, the disturbance magnetic field removing means may be a magnetic shield applied to the energizing electrode. The magnetic shield in this case may be one in which the energizing electrode is covered with a shielding material made of a ferromagnetic material. According to the magnetic shield, the influence of the disturbance magnetic field can be easily and effectively removed. The shield material may be a soft magnetic metal or a soft magnetic oxide. If it is soft magnetic, the influence of the disturbance magnetic field can be more effectively removed. The shape of the shield material may be a bead shape. The “bead shape” as used herein refers to a shape with a through hole, which may be cylindrical or ball-shaped. If it is a bead shape, it can be easily attached to the energizing electrode by passing the energizing electrode therethrough.

  In this invention, the energizing electrode and the magnetic field detecting means are integrated to form a detection head, and the disturbance magnetic field removing means directs the flow of current flowing through the energizing electrode from the side surface of the detection head to the inside. It is good as a thing. The above-mentioned "as one body" means as one assembly part that is fixed to each other.

  In the present invention, the energizing electrode is L-shaped, and the disturbance magnetic field removing means includes the energizing electrode, one end of which is located on a side surface of the detection head and the other end of the inspection target 1 of the detection head. It may be an electrode positioning means arranged so as to be positioned on the opposing surfaces.

  In the present invention, the material of all electrodes including the energization electrode in the detection head may be a non-magnetic material. Thus, if the material of all the electrodes in the detection head is a non-magnetic material, it is possible to further prevent the disturbance magnetic field from affecting the measurement of the magnetic field detection means.

  In the present invention, the current applied from the power source to the inspection object may be a direct current or an alternating current. A direct current and an alternating current may be switched and applied.

  When the current applied from the power source to the object to be inspected is an alternating current, the quality measuring means has a frequency change command unit that variously changes the frequency of the alternating current output from the power source, and the frequency change command unit It is good also as what has a function which measures the magnetic field in each frequency changed by (1), and measures quenching quality. In the case of this configuration, it is easy to change the frequency suitable for obtaining the quenching quality to be inspected.

  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 through the deeper part of the inspection object 1, so in order to know the quenching hardness at a deeper position, the magnetic field sensor is a low-frequency magnetic field. It is desirable to be able to measure

  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 this invention, the quality measuring means may inspect 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 A current-carrying electrode brought into contact with the surface of the object, a power source for applying a current to the inspection object via the current-carrying electrode, and a magnetic field detection means for measuring a magnetic field generated by a current flowing through the inspection object by the power source And the quality measuring means for measuring the quenching quality of the inspection object by the magnetic field measured by the magnetic field detection means, and the magnetic field generated by the current flowing outside the inspection object affects the measurement of the magnetic field detection means. Since it is provided with a disturbance magnetic field removing means for preventing the magnetic field from being applied, the quenching quality of the inspection object can be inspected with high accuracy by nondestructive inspection.

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. (A) is an expanded sectional view of the probe in the quenching quality inspection apparatus, and (B) is a perspective view of a shield material used for the magnetic shield of the energization electrode in the probe. It is an expanded sectional view showing other examples of composition of the probe. It is an expanded sectional view showing other examples of composition of the probe. It is an expanded sectional view showing other examples of composition of the probe. It is a block diagram which shows the structure of the hardening quality inspection apparatus concerning other embodiment of this invention. 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, the quenching quality is inspected by passing a current through the inspection object 1 and 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 the energizing current. As shown in FIG. 1, an alternating current is supplied from, or applied to, a power source 4 that is an alternating current power source via a pair of energizing electrodes 2 and 2 that are brought into 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 is a combination of 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 the magnetic field generated by the current flowing through the inspection object 1 by the power source 4. It is. 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 mold material 12 is mounted with the magnetic field sensor 5 and fills a gap between the sensor substrate 11 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 energizing electrodes 2 and 2 are arranged in parallel with a predetermined distance apart, and the magnetic field sensor 5 is arranged between the energizing 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.

  A magnetic shield 7 is applied to the pair of energizing electrodes 2 and 2. The magnetic shield 7 serves as disturbance magnetic field removing means for preventing the magnetic field generated by the current flowing outside the inspection object 1 from affecting the measurement of the magnetic field sensor 5. That is, in this case, the current flowing outside the inspection object 1 is the current flowing through the energization electrodes 2 and 2 so that the magnetic field generated by this current does not affect the measurement of the magnetic field sensor 5. A magnetic seal 7 is applied to the energizing electrodes 2 and 2. Here, the magnetic shield 7 is configured by covering a portion of the energizing electrodes 2 and 2 close to the magnetic field sensor 5 with a shielding material 10 made of a ferromagnetic material, as shown in an enlarged view in FIG. . The shape of the shield material 10 is, for example, a bead shape as shown in FIG. The shape of the shield material 10 may be a bead shape, and may be a cylindrical shape as illustrated or a ball shape. As the shielding material 10 in this case, a soft magnetic metal, a soft magnetic oxide, or the like can be used. As the soft magnetic metal, silicon steel, permalloy, amorphous alloy or the like can be used, and as the soft magnetic oxide, soft magnetic ferrite or the like can be used.

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 and amplitude 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 alternating current by the oscillation circuit 19. 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 variably set the frequency and amplitude 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 and amplitude of the AC signal output from the oscillation circuit 19 are variably set. In the frequency change command unit 20b, for example, a plurality of types of rules such as change width, frequency, change repetition period, etc. for changing the frequency are set in accordance with the type of the desired quenching quality, the type of the inspection object 1, and the like. Any rule may be selected by appropriate input.

  After the determination unit 20a calculates the quenching hardness of an arbitrary depth as described above, the frequency change command unit 20b 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, a quenching hardness having a depth different from the arbitrary depth is calculated in light of the signal based on the measured strength or magnitude and direction of the magnetic field and the relationship 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 signals based on the strength or magnitude and direction of the magnetic field at a plurality of frequencies may be temporarily stored, and the distribution of the quenching hardness in the depth direction may be estimated.

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 current is applied from the power source 4 to the inspection object 1 through the current-carrying electrodes 2 and 2, At this time, the magnetic field generated by the current flowing through the inspection object 1 is measured by the magnetic field sensor 5 which is a magnetic field detection means, and the quenching quality of the inspection object 1 is measured by the quality measurement means 18 based on the magnetic field measured by the magnetic field sensor 5. Since it did in this way, the quenching quality of the test object 1 can be test | inspected with a sufficient precision by nondestructive inspection.
In particular, by applying a magnetic shield 7 as a disturbance magnetic field removing means to the energizing electrodes 2 and 2, the disturbance magnetic field generated by the current flowing outside the inspection object 1, that is, the current flowing through the energizing electrodes 2 and 2 is removed. Then, since the disturbance magnetic field is prevented from affecting the measurement of the magnetic field sensor 5, the quenching quality of the inspection object 1 can be inspected with higher accuracy by nondestructive inspection.

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

FIG. 4 shows another configuration example of the probe 8 in the embodiment shown in FIGS. In this configuration example, the magnetic shield 7 is applied to all portions of the energization electrodes 2 and 2 in the probe 8 as a disturbance magnetic field removing means. Specifically, the magnetic shield 7 is applied to all parts in the sensor housing 13 of the probe 8, and only portions of the energizing electrodes 2 and 2 that protrude from the sensor housing 13 are exposed from the magnetic shield 7. Other configurations are the same as those in the example of FIG.
As described above, when the magnetic shield 7 is applied to all portions of the energization electrodes 2 and 2 in the probe 8, the influence of the disturbance magnetic field generated by the energization electrodes 2 and 2 on the measurement of the magnetic field sensor 5 is more reliably performed. Since it can remove, the quenching quality of the test object 1 can be test | inspected more accurately.

FIG. 5 shows still another configuration example of the probe 8 in the embodiment shown in FIGS. In this configuration example, as a disturbance magnetic field removing means, a magnetic shield 7 is applied to a portion of the probe 8 adjacent to the magnetic field sensor 5 of the energizing electrodes 2 and 2 and the sensor substrate 11 on which the magnetic field sensor 5 is mounted. A magnetic shield 7A is also provided on the surface opposite to the sensor mounting surface. In this case, the shield material 10 made of the same material as the magnetic shield 7 of the energization electrodes 2 and 2 is also used for the magnetic shield 7A. Other configurations are the same as those in FIG.
As described above, when the magnetic shield 7A is applied not only to the energizing electrodes 2 and 2 but also to the sensor substrate 11, the influence of the disturbance magnetic field generated by the energizing electrodes 2 and 2 on the measurement of the magnetic field sensor 5 is further ensured. Therefore, the quenching quality of the inspection object 1 can be inspected with higher accuracy.

FIG. 6 shows still another configuration example of the probe 8 in the embodiment shown in FIGS. In this configuration example, the energizing electrodes 2 and 2 are L-shaped. The disturbance magnetic field removing means functions to position the energizing electrodes 2 and 2 so that one end thereof is positioned on the side surface of the probe 8 and the other end is positioned on the surface of the probe 8 facing the inspection object 1. Positioning means 13a is responsible. Specifically, the electrode positioning means 13a in this case is a part of the sensor housing 13 that fixes the energization electrodes 2 and 2. That is, the disturbance magnetic field removing means in this case causes the current flowing through the energizing electrodes 2, 2 to flow inward from the side surface of the probe 8, which is the detection head, so that the current flowing through the energizing electrodes 2, 2 is The disturbance magnetic field to be generated is prevented from affecting the measurement of the magnetic field sensor 5. In this case, from the viewpoint of more reliably preventing the influence of the disturbance magnetic field on the measurement of the magnetic field sensor 5, the materials of all the electrodes such as the energizing electrodes 2, 2 and the electrodes 14, 15 in the probe 8 serving as the detection head are A non-magnetic material is desirable. Other configurations are the same as those in FIG.
As described above, even when the direction of the current flowing through the energizing electrodes 2 and 2 is directed from the side surface of the probe 8 to the inside, the disturbance magnetic field generated by the energizing electrodes 2 and 2 is measured by the magnetic field sensor 5. Therefore, the quenching quality of the inspection object 1 can be inspected with high accuracy.

FIG. 7 is a block diagram showing a configuration of a quenching quality inspection apparatus according to another embodiment of the present invention. In the following description, portions corresponding to the matters described in the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and redundant descriptions are omitted. In the example of FIG. 7, the measuring device 9A includes a DC power supply 4A. The signal processing unit 20A includes a determination unit 20a and a power supply control unit 20c. That is, the power supply control unit 20 c switches at least the direction and the magnitude of the current applied between the energization electrodes 2 and 2. The direction and magnitude of the current may be switched every predetermined time. The predetermined time may be an arbitrarily determined time. The quality measuring means 18 may process the signal of the magnetic field sensor 5 every time this current is switched. In this configuration, the quenching depth of the inspection object 1 can be measured.
Note that it is also possible to energize a test object with a single frequency current that does not change the frequency f through a pair of energization electrodes using an AC power source.
When a direct current is applied to the inspection object 1 using the DC power supply 4A, currents having different directions and magnitudes are applied to the inspection object 1 to increase the magnetic field strength for each current having a different direction and magnitude. The thickness or size and direction may be measured. 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 each of the above embodiments includes a magnetic impedance element (MI sensor, MI: Magneto-Impedance), a magnetoresistive element (MR sensor, MR: Magnetoresistive), and a giant magnetoresistive element (GMR sensor). , GMR: Giant Magnetoresistive), TMR sensor (TMR: Tunnel Magnetoresistive), 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 for energization 4, 4A ... Power supply 5 ... Magnetic field sensor (magnetic field detection means)
7. Magnetic shield (disturbance magnetic field removal means)
8 ... Probe (detection head)
DESCRIPTION OF SYMBOLS 10 ... Shield material 13 ... Sensor housing 13a ... Electrode positioning means 18 ... Quality measuring means 20b ... Frequency change command part

Claims (15)

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,
A current-carrying electrode that is brought into contact with the surface of the inspection object, a power source that applies a current to the inspection object via the current-carrying electrode, and a magnetic field that is generated by a current that flows through the inspection object is measured by the power source. The magnetic field detection means, the quality measurement means for measuring the quenching quality of the inspection object by the magnetic field measured by the magnetic field detection means, and the magnetic field generated by the current flowing outside the inspection object is measured by the magnetic field detection means. A quenching quality inspection device comprising disturbance magnetic field removing means for preventing the magnetic field from being affected.   2. The quenching quality inspection apparatus according to claim 1, wherein the disturbance magnetic field removing means is a magnetic shield applied to the energizing electrode.   3. The quenching quality inspection apparatus according to claim 2, wherein the magnetic shield is obtained by coating the energization electrode with a shielding material made of a ferromagnetic material.   The quenching quality inspection apparatus according to claim 3, wherein the shield material is a soft magnetic metal.   The quenching quality inspection apparatus according to claim 3, wherein the shield material is a soft magnetic oxide.   The quenching quality inspection apparatus according to any one of claims 3 to 5, wherein the sealing material has a bead shape.   2. The detection head according to claim 1, wherein the current-carrying electrode and the magnetic field detection unit are integrated to form a detection head, and the disturbance magnetic field removal unit directs a current flow through the current-carrying electrode from a side surface of the detection head to the inside. Quenching quality inspection equipment that can be changed.   8. The energizing electrode according to claim 7, wherein the energizing electrode is L-shaped, and the disturbance magnetic field removing means includes the energizing electrode, one end of which is located on a side surface of the detection head and the other end of the inspection target portion of the detection head. A quenching quality inspection device which is an electrode positioning means arranged so as to be positioned on the opposing surfaces.   9. The quenching quality inspection apparatus according to claim 7, wherein all electrodes including the energization electrode in the detection head are made of a non-magnetic material.   The quenching quality inspection apparatus according to any one of claims 1 to 9, wherein a current applied from the power source to the inspection object is a direct current.   The quenching quality inspection apparatus according to claim 1, wherein a current applied from the power source to the inspection object is an alternating current.   In Claim 11, the quality measuring means has a frequency change command section that variously changes the frequency of the alternating current output from the power source, and measures the magnetic field at each frequency changed by the frequency change command section, A quench quality inspection device having a function of measuring quench quality.   13. 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 13, 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 measurement means according to any one of claims 1 to 14, wherein the quenching quality is at least one of a surface hardness, a quenching hardness distribution in a depth direction, and a quenching depth of the inspection object. Quenching quality inspection equipment to inspect.

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