JP5668511B2 - Eddy current measuring sensor and eddy current measuring method - Google Patents

Description

  The present invention relates to a sensor for eddy current measurement and a eddy current measurement method, and more particularly to a technique for improving measurement accuracy by eddy current measurement.

  For example, mechanical parts such as automobile and motorcycle engine parts and undercarriage parts are made of steel (hereinafter referred to as steel) that has been subjected to induction hardening of metal (conductor) and induction-hardened. Yes. In the induction hardening of the steel material, the effective hardened layer depth and the total hardened layer depth are standardized with respect to the hardened layer depth (hereinafter referred to as a hardened depth) of surface hardening and its hardness. For this reason, in order to guarantee the quality of steel materials, it is necessary to measure and evaluate the quenching depth and hardness.

Conventionally, the quenching depth and hardness of the steel material are obtained by partially cutting the steel material sampled as a sample and measuring the cross-sectional strength with various hardness meters such as a Vickers hardness meter. Was evaluated.
However, this destructive inspection method discards the steel material used as a sample, leading to an increase in material costs. In addition, since the time required for the inspection becomes long, and in-line inspection is impossible, there is a possibility that a defect that occurs on a single occasion cannot be found and carried out to the next process.

Then, the technique of measuring the quenching depth and hardness of steel materials using the eddy current type | mold inspection which is a nondestructive inspection is known (for example, refer patent document 1 to patent document 3).
In the eddy current inspection, an alternating magnetic field is caused to approach the steel material to generate an alternating magnetic field, the eddy current is generated in the steel material by the alternating magnetic field, and an induced magnetic field induced by the eddy current is detected. It is detected by a coil. In other words, the eddy current type inspection can quantitatively measure the quenching depth and hardness of the steel material in a short time and through the 100% inspection without discarding the steel material.
The eddy current inspection includes a quenching depth / hardness measurement test (hereinafter referred to as a quenching depth measurement test) for measuring the quenching depth and hardness of the steel material, and cracks generated on the surface of the inspection object. It is also used for a flaw detection test for detecting a flaw such as a foreign material, a foreign material discrimination test for detecting a foreign substance contained in an inspection object, and the like.

  The steel material has a difference in magnetic permeability between the base material and martensite generated in the hardened layer. Therefore, when a steel material is measured using an eddy current sensor, the voltage (amplitude) detected by the detection coil changes as the quenching depth changes. Further, the voltage detected by the detection coil monotonously decreases as the hardened layer depth increases. In the quenching depth measurement test, the quenching depth of steel can be calculated using these phenomena.

For example, according to the technique described in Patent Document 1, the penetration depth is used to inspect the quenching depth of the shaft portion of the shaft object component. The penetration coil has a stronger magnetic field than a probe-type coil (hereinafter simply referred to as a “probe-type coil”) in which the probe is composed of a coil whose axial direction is perpendicular to the steel material and the quenching depth is obtained. Since it is not necessary to precisely control the distance to the steel material, it is suitable for the quenching depth measurement test.
However, since the diameter of the inner circumference that is the measurement part of the penetration coil is constant, the filling ratio of the measurement site to the penetration coil (ratio of the cross-sectional area at the measurement site of the steel material to the inner circumference cross-sectional area of the penetration coil) is It varies depending on the outer diameter at the measurement site. Since the inspection accuracy of the eddy current type inspection decreases exponentially when the filling rate becomes low, according to the conventional technique, there is a problem that a difference in inspection accuracy occurs due to a change in the outer diameter of the steel material for each measurement site. was there.
Moreover, since it is necessary to insert the steel material which is a test object through a penetration coil, it was limited to the shaft object component in which an outer diameter is substantially constant. In other words, it has been difficult to make a part whose outer diameter changes greatly, such as a crankshaft, as an inspection object.

In addition, according to the technique described in another example of Patent Document 2, the quenching depth of the steel material is measured using a probe-type coil.
About the said quenching depth measurement test, since the ratio of the signal component to detect with respect to a noise component is small compared with another flaw detection test and a different material discrimination test, higher detection accuracy is calculated | required. In the probe type coil, it is necessary to generate a strong magnetic field by increasing the coil diameter in order to ensure detection accuracy. However, when measuring the quenching depth of a concave portion (for example, a fillet portion formed between an arm of a crankshaft and a pin portion or a journal portion) as shown in FIG. Therefore, the lift-off, which is the distance between the probe type coil and the measurement site, is increased. As the lift-off increases, the measurement accuracy decreases, so it is difficult to use a probe-type coil at the measurement site as described above.

Further, according to the technique described in Patent Document 3, the so-called potentiometric method is used to measure the quenching depth of the steel material.
The potential difference method uses the fact that there is a correlation between the quenching depth of the object to be measured and the electrical resistivity. The probe is brought into contact with any two points in the steel, and the quenching depth of the steel is determined from the potential difference between the two points. This is a technique for calculating the thickness.
However, according to the present technology, since the probe is in contact with the steel material, the influence of the surface properties of the steel material and the wear of the probe is increased. In addition, since the resistivity of steel materials changes due to temperature changes, there is a problem that it is difficult to measure in an environment with temperature changes.

JP 2009-133694 A JP 2007-40865 A JP 2009-47664 A

  In view of the above, the present invention can perform a quenching depth measurement test with high detection accuracy even when inspecting an induction-hardened component whose outer diameter changes greatly or has a recess. In addition, the present invention provides a sensor for eddy current measurement and a eddy current measurement method that can improve the measurement accuracy by eliminating the influence of lift-off in measuring the quenching depth.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, in claim 1, an excitation unit for applying a predetermined AC excitation signal to a measurement site formed along an intersecting line where two surfaces intersect in a measurement target component, and the applied AC excitation A sensor for eddy current measurement, comprising: a detection unit for detecting a detection signal generated in the measurement site by a signal; and a calculation unit for calculating the detection signal as an eddy current measurement value, wherein the excitation unit Is a coil wound around a straight line that intersects with one of the two virtual planes and does not intersect with the intersection of the two virtual planes. Is formed so that the outer shape thereof is substantially the same as the shape of the measurement site, and the excitation unit is close to the measurement site in a posture facing the measurement site. In the placed state, An AC voltage as an AC excitation signal is generated, and a magnetic field is generated in the measurement site, an eddy current is generated by the magnetic field, an induced voltage generated by the eddy current is detected by the detection unit as a detection signal, A calculation part calculates the said detection signal as an eddy current measurement value, and measures the hardening depth in measurement object components based on this eddy current measurement value.

  According to a second aspect of the present invention, the exciting portion is covered with a case in which a portion not facing the measurement site is a magnetic material.

According to a third aspect of the present invention, there is provided an excitation unit for applying a predetermined AC excitation signal to a measurement site formed along an intersection line where two surfaces intersect in a measurement target component, and the applied AC excitation signal. A detection unit for detecting a detection signal generated in the measurement site; and a calculation unit for calculating the detection signal as an eddy current measurement value, and the excitation unit is formed by extending the two surfaces. A coil wound around a straight line that does not intersect the intersection line of the two virtual surfaces and intersects one of the two virtual surfaces is wound along the intersection line in a part thereof, An eddy current measurement method using an eddy current sensor formed so that an outer shape thereof is substantially the same as a shape of a measurement part, wherein the detection part measures the excitation part in a posture facing the measurement part. In a state of being placed close to the part An AC voltage is applied to the coil as an AC excitation signal, a magnetic field is generated in the measurement site, an eddy current is generated by the magnetic field, and an induced voltage generated by the eddy current is detected as a detection signal by the detection unit, The calculation unit calculates the detection signal as an eddy current measurement value, and measures the quenching depth in the measurement target component based on the eddy current measurement value.

  According to a fourth aspect of the present invention, the exciting portion is covered with a case where a portion not facing the measurement site is a magnetic material.

  As effects of the present invention, the following effects can be obtained.

  According to the present invention, it is possible to perform a quenching depth measurement test with high detection accuracy even when inspecting induction-quenched parts whose outer diameter greatly changes or has concave portions, It is possible to improve measurement accuracy by eliminating the effect of lift-off when measuring the height.

The figure which shows the relationship of the layer state of the depth direction of a hardening member, hardness, and magnetic permeability. The schematic diagram which shows the apparatus structure for performing the eddy current measurement which concerns on this embodiment. The figure which shows the relationship between the alternating current excitation signal and detection signal in eddy current measurement. The figure which showed the crankshaft which is an example of the measuring object of the sensor for eddy current measurement. (A) to (c) is a diagram showing a schematic shape of a coil and a positional relationship between a journal portion and an arm of the crankshaft and the coil. (A) is the front view which showed the exciting coil in the sensor for eddy current measurement which concerns on 1st embodiment, (b) is the sectional view on the AA line in (a). (A) is the front view which showed the sensor for eddy current measurement which concerns on 1st embodiment, (b) is the sectional view on the AA line in (a). (A) is the front view which showed the state which is performing the eddy current measurement with the sensor for eddy current measurement which concerns on 1st embodiment, (b) is the sectional view on the AA line in (a). (A) is the front view which showed the state which is performing the eddy current measurement with the sensor for eddy current measurement which concerns on 2nd embodiment, (b) is the sectional view on the AA line in (a). Sectional drawing which showed the state which is performing the eddy current measurement of the shaft member with the sensor for eddy current measurement which concerns on 2nd embodiment. The figure which showed the eddy current measurement value detected with the sensor for eddy current measurement which concerns on a prior art.

Next, embodiments of the invention will be described.
It should be noted that the technical scope of the present invention is not limited to the following examples, but broadly covers the entire scope of the technical idea that the present invention truly intends, as will be apparent from the matters described in the present specification and drawings. It extends.

  The present invention intends to expand the application range of eddy current measurement by devising the arrangement and connection method of the excitation coil, which is an excitation part, and the detection coil, which is a detection part, of the sensor for eddy current measurement. is there. Embodiments of the present invention will be described below. In the embodiment of the present invention, the eddy current measurement by the eddy current sensor is mainly used for the inspection of the quenching quality (quenching depth and quenching hardness) of the quenched part by induction hardening or the like. This will be described as an example. That is, by performing eddy current measurement using a sensor for eddy current measurement, the quenching quality of the quenched part that is the measurement target part is inspected.

  FIG. 1 shows the relationship between the layer state, hardness, and magnetic permeability in the depth (distance from the surface) direction of a quenched member that is a hardened steel material (such as S45C). As shown in FIG. 1, in the quenched member, as a schematic structure of the hardened member, from the surface side, a hardened layer 1 that is a portion subjected to quenching and a mother layer 2 that is a portion of the base material are , Formed through the boundary layer 3. Referring to the hardness change curve 4, the cured layer 1 and the mother layer 2 have different hardnesses, and the hardness of the cured layer 1 is larger than that of the mother layer 2. In the boundary layer 3, the hardness gradually decreases from the hardened layer 1 side to the mother layer 2 side. As a specific example of the hardness, Vickers hardness (Hv) is shown, and the hardened layer 1 has a hardness of about Hv = 600 to 700, and the mother layer 2 has a hardness of about Hv = 300.

  On the other hand, referring to the permeability change curve 5, the change in the magnetic permeability with respect to the distance from the surface of the quenched member is substantially inversely proportional to the change in the hardness with respect to the distance from the surface of the quenched member. In other words, the magnetic permeability of the hardened layer 1 is smaller than that of the mother layer 2 and the boundary layer 3 gradually increases from the hardened layer 1 side to the mother layer 2 side. In the eddy current measurement according to the present embodiment, the relationship between the hardness and the permeability with respect to the distance from the surface in such a quenched member is used.

  An outline (measurement principle) of a device configuration for performing eddy current measurement according to the present embodiment will be described with reference to FIG. As shown in FIG. 2, in the eddy current measurement, an eddy current measurement having an excitation coil 7 as an excitation part and a detection coil 8 as a detection part with respect to a measurement part 6a of a workpiece (magnetic body) 6 as a measurement target component. Sensor 9 is set at a predetermined position. In such a configuration, when a current is supplied to the exciting coil 7, a magnetic field is generated around the exciting coil 7. Then, an eddy current is generated in the vicinity of the surface of the measurement site 6a of the workpiece 6 that is a magnetic body by electromagnetic induction (see arrow C1 in FIG. 2). As the eddy current is generated on the surface of the measurement site 6a, the magnetic flux penetrates the detection coil 8, and an induced voltage is generated in the detection coil 8. Then, the induced voltage is measured by the detection coil 8.

  Both ends (both terminals) of the exciting coil 7 are connected to the AC power source 10. The AC power supply 10 applies a predetermined AC excitation signal (excitation AC voltage signal) V <b> 1 to the excitation coil 7. Both ends (both terminals) of the detection coil 8 are connected to the measuring device 11. The measuring device 11 includes the magnitude of the detection signal (voltage signal for the induced voltage) V2 obtained from the detection coil 8 when the AC excitation signal V1 from the AC power supply 10 is applied to the excitation coil 7, and the detection signal V2. A phase difference (phase delay) Φ (see FIG. 3) with respect to the AC excitation signal V1 is detected. Here, in order to detect the phase difference Φ, the AC excitation signal V1 (waveform) is given to the measurement device 11 as the amplified phase detection.

  The detection signal V2 detected by the detection coil 8 reflects the magnetic permeability of the measurement site 6a (workpiece 6). That is, when the permeability of the measurement site 6a increases, the magnetic flux accompanying the generation of the eddy current as described above increases and the detection signal V2 increases. Conversely, when the permeability of the measurement site 6a is reduced, the magnetic flux accompanying the generation of eddy current is reduced and the detection signal V2 is reduced. In order to quantify (numerize) the detection signal V2 based on this eddy current, as shown in FIG. 3, the amplitude value Y, which is the magnitude of the detection signal V2, and the position of the detection signal V2 relative to the AC excitation signal V1. The value X (= Y cos Φ), which is a value resulting from the phase difference Φ, is focused and the following knowledge is obtained.

  First, the amplitude value Y of the detection signal V2 may have a correlation with the hardened surface hardness (hardness of the hardened portion). That is, as can be seen from a comparison between the hardness change curve 4 and the permeability change curve 5 in FIG. 1, there is a relationship that the permeability is high when the quenching surface hardness is low. When the magnetic permeability is high, the magnetic flux generated when the AC excitation signal V1 is applied to the excitation coil 7 increases, and the eddy current induced on the surface of the measurement site 6a also increases. Along with this, the amplitude value Y of the detection signal V2 detected by the detection coil 8 also increases. Therefore, conversely, from the amplitude value Y of the detection signal V2 detected by the detection coil 8, the magnetic flux penetrating the measurement site 6a where the eddy current is generated, that is, the magnetic permeability, is derived. Thereby, the quenching surface hardness can be understood from the relationship between the hardness change curve 4 and the permeability change curve 5 shown in FIG.

  Next, the value X resulting from the phase difference Φ of the detection signal V2 with respect to the AC excitation signal V1 may have a correlation with the quenching depth (depth of the quench-hardened layer). That is, when the quenching depth becomes deep, that is, the hardened layer 1 hardened in the quenching member increases, the low permeability range increases in the depth direction, and the AC excitation signal V1 is increased. The phase delay of the detection signal V2 will increase. Thereby, the depth of the quenching depth can be determined from the magnitude of the value X caused by the phase difference Φ.

  In the eddy current measurement for inspecting the quenching quality of the hardened part by the measurement principle as described above, the eddy current measurement sensor having the excitation coil and the detection coil is used as described above. Hereinafter, the configuration of the eddy current measuring sensor will be described as an embodiment of the present invention.

[First embodiment]
First, a crankshaft CS that is an example of a measurement target of the eddy current measurement sensor according to the first embodiment will be described with reference to FIG. Note that the measurement target of the eddy current measurement sensor according to the present embodiment is not limited to the crankshaft CS, and other steel materials as described later can be measured.

  As shown in FIG. 4, the crankshaft CS is used for an in-line four-cylinder engine, and is a steel material formed integrally by forging. Then, five journal portions J arranged along the axis of the crankshaft CS, an arm A continuously provided adjacent to the journal portion J, and a pair of arms A arranged opposite to each other And four pin portions P respectively installed between them. Further, fillet is provided between the journal portion J and the arm A and between the pin portion P and the arm A (circumferential portion that is a boundary between the journal portion J and the pin portion P and the arm A). A fillet portion F, which is a portion, is formed. In the present embodiment, the quenching depth is measured by eddy current measurement for the fillet portion F formed between the journal portion J and the arm A (see FIG. 8B).

  Next, the schematic shape of the coil C used in the excitation part of the sensor for eddy current measurement according to the present embodiment and the positional relationship between the journal part J and arm A and the coil C are shown in FIG. This will be described using c).

  As shown in FIG. 5, the coil C is formed in a substantially rectangular shape. Then, one side of the tip side of the coil C (the side facing the fillet portion F in FIG. 5B) is inwardly arcuate so as to form an angle of about 45 degrees with respect to the plane on which the other three sides are located. Is formed to protrude. Specifically, one side of the coil C on the tip side is formed in an arc shape having a curvature that substantially matches the outer shape of the journal portion J. That is, as shown in FIGS. 5A and 5B, when the coil C is disposed opposite the fillet portion F at an angle of about 45 degrees with respect to the arm A, one side of the tip side is the fillet portion F. It is formed so as to follow.

  As an assembly of the coils C formed as described above, the exciting coil 51 in the eddy current measuring sensor according to the present embodiment is formed. Then, as shown in FIGS. 6A and 6B, an exciting part 51 a is formed on the tip side of the exciting coil 51. Specifically, by winding the conducting wire in such a shape that the coils C are arranged in the vertical direction and the horizontal direction, the surface on the horizontal direction side of the exciting portion 51a which is the tip portion of the exciting coil 51 is flat, The side surface is formed into a curved surface.

  When eddy current measurement is performed on the fillet portion F of the crankshaft CS using the eddy current measurement sensor according to the present embodiment, the exciting coil 51 is disposed to face the fillet portion F at an angle of about 45 degrees with respect to the arm A. . In other words, the excitation coil 51 is wound around an axis centering in a direction of 45 degrees with respect to the arm A that does not intersect with the fillet portion F that is a measurement site. In this state, the excitation portion 51a is In a part of the exciting coil 51, the horizontal side surface of the exciting part 51 a is formed so as to face the arm A, and the lower side face is opposed to the journal part J. That is, when the exciting part 51a is arranged so that the exciting coil 51 is opposed to the fillet part F, the outer shape of the exciting part 51a is substantially the same as the shape of the fillet part F (the lateral side surface of the exciting part 51a). And the lower side surface is formed so as to be parallel to the arm A and the journal portion J (see FIGS. 8A and 8B).

  In the eddy current measurement sensor, the excitation coil 51 is wound around the axis centered in the circumferential direction of the journal portion J that is parallel to the arm A among the directions not intersecting the fillet portion F that is the measurement site. It can be set as the structure rotated. Even in this case, the exciting part 51a can be formed so that the outer shape of the exciting part 51a is substantially the same as the shape of the fillet part F when the exciting coil 51 is arranged facing the fillet part F. is there. In other words, if the axial direction of the exciting coil 51 is not a direction that intersects the fillet portion F, a eddy current measuring sensor can be configured.

As shown in FIG. 7A, the eddy current measurement sensor according to the present embodiment includes not only the excitation coil 51 but also a detection coil 61 and a calculation unit 41 which are detection units.
As described above, a predetermined alternating current excitation signal (see the alternating current excitation signal V1) is applied to the exciting coil 51 in a state of being disposed facing the fillet portion F of the crankshaft CS that is a measurement target component. The detection coil 61 detects a detection signal (see the detection signal V2) due to an eddy current generated in the measurement target component by the excitation unit to which the AC excitation signal is applied. Moreover, the calculating part 41 is electrically connected with the detection coil 61 mentioned later, and calculates a detection signal as an eddy current measurement value.

Both ends (both terminals) of the exciting coil 51 are connected to an AC power source (not shown). That is, the excitation coil 51 applies a predetermined AC excitation signal to the measurement target component.
The detection coil 61 includes a plurality of detection coils 61a disposed on the horizontal side surface of the excitation unit 51a, and a plurality of detection coils 61b disposed on the lower side surface of the excitation unit 51a.
In the present embodiment, a thin film planar coil is used as the detection coil 61, but other coils such as a pancake coil can also be used.
Both ends (both terminals) of each detection coil 61 are connected to a measurement device (not shown) included in the calculation unit 41. That is, the detection coil 61 detects a detection signal due to eddy current from the measurement target component to which the AC excitation signal is applied.

  When the quenching depth of the measurement target component is measured using the eddy current measurement sensor configured as described above, the detection coil 61 faces the fillet portion F as shown in FIGS. In a state in which the excitation coil 51 is disposed close to the measurement target component in a posture (the posture in which the detection coil 61a faces the fillet portion F on the arm A side and the detection coil 61b faces the fillet portion F on the journal portion J side). Then, a voltage is applied to the exciting coil 51 by an AC power source.

  At the moment when a current flows through the exciting coil 51, a rotating magnetic field is generated around the exciting portion 51a and the fillet portion F in accordance with the right-handed screw law as shown in FIG. In addition, electromagnetic induction is caused by this rotating magnetic field, and eddy current is generated in the fillet portion F, which is a magnetic body, by electromagnetic induction. Further, as the eddy current is generated on the surface of the fillet portion F, the magnetic flux is passed through the detection coil 61 and an induced voltage is generated in the detection coil 61. Then, the detection coil 61 measures the induced voltage as a detection signal. And the calculating part 41 calculates a detection signal as an eddy current measurement value, and measures the quenching depth in the fillet part F based on this eddy current measurement value.

  Further, by rotating the eddy current measurement sensor in the circumferential direction of the journal portion J in a state where the sensor for eddy current is brought close to the fillet portion F, the circular fillet portion F can be measured as a whole. That is, it becomes possible to detect an unquenched portion generated in the circumferential direction.

  According to the eddy current measurement sensor according to the present embodiment, as described above, the eddy current measurement sensor is brought close to the fillet portion F to measure the eddy current, so that the outer diameter changes greatly or has a recess. Even when an induction-hardened part is inspected, a quenching depth measurement test can be performed with high detection accuracy. That is, as shown in FIGS. 8A and 8B, the excitation part 51a of the eddy current measurement sensor is formed along the shape of the fillet part F, so that the eddy current measurement sensor and the fillet part F to be measured are measured. Therefore, it is possible to reduce the lift-off, which is the distance between the two, and it is possible to prevent a decrease in measurement accuracy.

  In addition, since the sensor for measuring eddy currents is not brought into contact with the measurement target, it is not affected by the surface properties of the steel material or the wear of the probe, and it is possible to prevent the measurement accuracy from being deteriorated due to temperature change. .

  As described above, according to the eddy current measurement sensor according to the present embodiment, the quenching depth can be obtained with a high detection accuracy even when inspecting an induction-quenched part whose outer diameter changes greatly or has a recess. A measurement test can be performed, and the measurement accuracy can be improved by eliminating the influence of lift-off in measuring the quenching depth.

[Second Embodiment]
Next, an eddy current measurement sensor according to a second embodiment of the present invention will be described with reference to FIGS. In addition, about the eddy current measurement sensor demonstrated in this embodiment, detailed description shall be abbreviate | omitted regarding the part which is common in previous embodiment.

  In the sensor for eddy current measurement according to the present embodiment, a portion of the exciting portion 51a that does not face the fillet portion F (portion where the detection coil 61 is not disposed) is covered with a case 52 that is a magnetic body. Specifically, as shown in FIGS. 9A and 9B, a magnet formed in a plate cylinder shape on the surface of the excitation portion 51a that does not face the fillet portion F (arm A and journal portion J) to be measured. It is constructed by covering the body case 52.

  In the present embodiment, the rotating magnetic field generated around the excitation unit 51a during eddy current measurement is transmitted through the case 52 by the configuration as described above, so that the excitation unit 51a is opposed to the first embodiment. It is possible to concentrate the magnetic flux on the fillet portion F to be performed. That is, even if the AC voltage applied to the exciting coil 51 is the same, the eddy current generated in the fillet portion F can be increased, so that the quenching depth measurement test can be performed with higher detection accuracy. .

  Since the case 52 may be a magnetic material, iron or the like can be used. However, from the viewpoint of concentrating the magnetic flux as described above, the case 52 is made of a ferromagnetic material such as ferrite, silicon steel plate or pearlite. It is desirable to form.

  The sensor for eddy current measurement according to the present embodiment (or the first embodiment) can measure a steel material other than the crankshaft. Specifically, for example, as shown in FIG. 10, eddy current measurement can be performed on a shaft member S whose outer diameter changes greatly due to unevenness on the surface. Even in this case, the excitation part 51a of the eddy current measuring sensor can be formed along the shape of the shaft member S, and the eddy current measurement can be performed by bringing the eddy current measuring sensor close to the recess of the shaft member S. As a result, the lift-off, which is the distance between the eddy current measurement sensor and the measurement target, can be reduced, so that it is possible to prevent a decrease in measurement accuracy.

41 Calculation Unit 51 Excitation Coil 51a Excitation Unit 61 Detection Coil

Claims (4)

An excitation unit for applying a predetermined AC excitation signal to a measurement site formed along an intersecting line where two surfaces intersect in a measurement target component, and generated in the measurement site by the applied AC excitation signal An eddy current measurement sensor comprising: a detection unit for detecting a detection signal; and a calculation unit for calculating the detection signal as an eddy current measurement value,
The excitation unit does not intersect the intersection line of two virtual surfaces extending the two surfaces, and a coil wound around a straight line intersecting one of the two virtual surfaces is a part thereof. By being wound along the intersecting line, the outer shape is formed to be substantially the same as the shape of the measurement site,
In the state where the detection unit faces the measurement site and the excitation unit is disposed close to the measurement site, an AC voltage is applied to the coil as an AC excitation signal to generate a magnetic field in the measurement site, and the magnetic field Eddy current is generated by the above, and the detection unit detects the induced voltage generated by the eddy current as a detection signal,
The calculation unit calculates the detection signal as an eddy current measurement value, and measures the quenching depth in the measurement target component based on the eddy current measurement value.
A sensor for measuring eddy currents. The excitation part is covered with a case where the part that does not face the measurement site is a magnetic body,
The eddy current sensor according to claim 1, wherein An excitation unit for applying a predetermined AC excitation signal to a measurement site formed along an intersecting line where two surfaces intersect in a measurement target component, and generated in the measurement site by the applied AC excitation signal A detection unit for detecting a detection signal; and a calculation unit for calculating the detection signal as an eddy current measurement value, wherein the excitation unit is an intersection of two virtual surfaces obtained by extending the two surfaces A coil wound around a straight line that intersects one of the two imaginary planes as a center is wound along the intersecting line, so that the outer shape is measured. An eddy current measurement method using an eddy current sensor formed to be substantially the same as the shape of
In the state where the detection unit faces the measurement site and the excitation unit is disposed close to the measurement site, an AC voltage is applied to the coil as an AC excitation signal to generate a magnetic field in the measurement site, and the magnetic field The eddy current is generated by the eddy current, the induced voltage generated by the eddy current is detected by the detection unit as a detection signal, the calculation unit calculates the detection signal as the eddy current measurement value, and the measurement target is based on the eddy current measurement value. Measure the quenching depth of parts
A method for measuring eddy currents. The excitation part is covered with a case where the part that does not face the measurement site is a magnetic body,
The eddy current measuring method according to claim 3, wherein:

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