JP5233909B2 - Eddy current type inspection apparatus and eddy current type inspection method - Google Patents

Description

  The present invention relates to an eddy current inspection apparatus and an eddy current inspection method, and more particularly to a technique for improving inspection accuracy in an eddy current inspection.

  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, measuring the cross-sectional strength with various hardness meters such as a Vickers hardness meter, and the quenching depth and hardness from the results. 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 which measures the hardening depth and hardness of steel materials using the eddy current type | mold test | inspection which is a nondestructive test | inspection is known (for example, refer patent document 1, patent document 2, and patent document 3).
In eddy current inspection, an alternating magnetic field is generated by bringing an exciting coil that has passed an alternating current close to the steel material, an alternating magnetic field is generated in the steel material, an eddy current is generated in the steel material, 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 for measuring the quenching depth and hardness of the steel material as well as a flaw detection test for detecting scratches such as cracks generated on the surface of the inspection object. It is also used in a foreign material discrimination test for detecting foreign matter contained in an inspection object.

  In the quenching depth / hardness measurement test, the electrical conductivity of the steel material varies between the base material and martensite generated in the hardened layer. Therefore, if steel material is measured using an eddy current sensor, the voltage (amplitude) detected by the detection coil changes as the quenching depth changes, and the voltage detected by the detection coil increases the depth of the hardened layer. Since it decreases monotonically, the quenching depth of steel can be calculated using these phenomena.

For example, according to the technique described in Patent Document 1, the quenching depth of the steel material is measured using a probe-type coil.
The quenching depth / hardness measurement test requires a higher detection accuracy because the ratio of the signal component to be detected relative to the noise component is small compared to other flaw detection tests and different material discrimination tests. However, since the probe type coil has a weak magnetic field and the distance from the steel material needs to be precisely controlled, it can be applied to the flaw detection test and the foreign material discrimination test, but it is adopted for the quenching depth / hardness measurement test. It was difficult.

Moreover, according to the technique of the said patent document 2, it is set as the structure which test | inspects the hardening depth of the axial part of a shaft component part using a penetration coil. The penetrating coil has a stronger magnetic field than the probe-type coil and does not require precise control of the distance from the steel material, so it is suitable for the quenching depth / hardness 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. As the filling rate decreases, the inspection accuracy of the eddy current inspection decreases exponentially. Therefore, according to the prior art, there is a problem that a difference in inspection accuracy occurs due to a change in outer diameter for each measurement site. It was.
Furthermore, since the steel material that is the object to be inspected needs to be inserted through the through coil, it has been limited to shaft object parts having a substantially constant outer diameter. In other words, it has been difficult to make a part whose outer diameter changes greatly, such as a crankshaft, as an inspection object.

Moreover, according to the technique of the said patent document 3, it forms the measurement part which penetrates the steel material which is a test object combining a some ring-shaped coil, and changes the mutual positional relationship of this ring-shaped coil. Therefore, the size of the measurement part is changed according to the outer diameter of the steel material, and the eddy current type inspection which is a flaw detection test is performed.
However, in the configuration in which the ring-shaped coils are combined, there is a problem in that the eddy current generated in the steel material is affected by the alternating magnetic field generated by the portion other than the vicinity of the measurement portion in the ring-shaped coil, and the inspection accuracy is lowered. Further, since the technique described in Patent Document 3 is intended for a flaw detection test, there is a possibility that the inspection accuracy may be insufficient when applied to the quenching depth / hardness measurement test.

JP 2009-47664 A JP 2009-31224 A JP 2000-162190 A

  Therefore, in view of the above situation, the present invention can inspect an induction-hardened component whose outer diameter changes greatly, because it can be inspected with high inspection accuracy regardless of the measurement site even for an inspection object whose outer diameter changes. Therefore, the present invention provides an eddy current inspection device and an eddy current inspection method that can be applied to a quenching depth / hardness measurement test.

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

That is, according to the first aspect of the present invention, a plurality of rod-shaped inspection means having an excitation coil and a detection coil disposed therein are provided, and all of the inspection means in a portion partitioned by combining the plurality of inspection means are provided. On the other hand, an alternating current is passed through the exciting coil in a state where the inspection object is inserted into the inner measurement part, thereby generating an alternating magnetic field in the measurement part, and the alternating magnetic field generates an eddy current in the inspection object. An eddy current type inspection apparatus for detecting an induced magnetic field induced by the eddy current by the detection coil, wherein the mutual positional relationship among the plurality of inspection means is changed according to the diameter of the inspection object By doing so, the size of the measurement unit is configured to be changeable, the detection coil is configured by arranging a plurality of detection coil blocks along the length direction of the inspection means, Among the serial inspection means, said detection coil block measurement unit and the adjacent portions detects the induced magnetic field by the detection coil block area which is not adjacent to the measurement portion is configured so as not to detect the induced magnetic field In the inspection means, the region for detecting the induced magnetic field is switched according to the size of the measurement unit .

  According to a second aspect of the present invention, three ring-shaped eddy current sensors are provided as the plurality of inspection means.

4. The excitation coil according to claim 3, wherein a plurality of excitation coil blocks are arranged along a length direction of the inspection means, and a portion of the inspection means that forms the measurement portion of the excitation coil. is configured to block flowing the alternating current, one of the inspection means, the exciting coil block portion adjacent to the measuring unit to flow the alternating current, the excitation coil block portion which is not adjacent to the measurement unit By being configured not to pass the alternating current, the region in which the alternating current is passed in the inspection means can be switched according to the size of the measurement unit .

  According to a fourth aspect of the present invention, an alternating current is passed through the exciting coil so that eddy currents in the same direction are generated in the inspection object.

  According to a fifth aspect of the present invention, in the inspection means for detecting the portion to be inspected with high accuracy of the inspection object, the frequency of the alternating current passed through the exciting coil is relatively set as compared with the inspection means for detecting the other portion. Set it low.

  According to a sixth aspect of the present invention, the inspection object is a steel material that has been induction-hardened, and measures the quenching depth and hardness of the inspection object.

According to a seventh aspect of the present invention, an inspection object is inserted into a measuring portion that is inside with respect to all the inspection means in a portion that is divided by combining a plurality of inspection means having an excitation coil and a detection coil disposed therein. In this state, an alternating current is passed through the exciting coil to generate an alternating magnetic field in the measurement unit, an eddy current is generated in the inspection object by the alternating magnetic field, and an induced magnetic field induced by the eddy current is converted into the induced magnetic field. An eddy current inspection method for detecting by a detection coil, wherein the size of the measurement unit is changed by changing the mutual positional relationship among the plurality of inspection means according to the diameter of the inspection object. together, the detection coil is constituted by disposing a plurality of detection coil block along the length of the inspection unit, among the inspection means, detecting the U-portion adjacent to the measuring unit Le block detects the induced magnetic field, by detecting coil block area which is not adjacent to the measurement unit does not detect the induced magnetic field, an area for detecting the induced magnetic field in said inspection means the magnitude of the measuring section It is switched accordingly .

9. The excitation coil according to claim 8, wherein the excitation coil is configured by arranging a plurality of excitation coil blocks along a length direction of the inspection means, and a portion of the inspection means that forms the measurement unit. block to flow the alternating current, one of the inspection means, the exciting coil block portion adjacent to the measuring unit to flow the alternating current, the excitation coil block portion which is not adjacent to the measuring unit of the alternating current By not flowing, the region in which the alternating current flows in the inspection means is switched according to the size of the measurement unit .

  According to a ninth aspect of the present invention, an alternating current is passed through the exciting coil so that an eddy current in the same direction is generated in the inspection object.

  According to a tenth aspect of the present invention, in the inspection means for detecting the portion to be inspected with high accuracy of the inspection object, the frequency of the alternating current flowing through the exciting coil is relatively set as compared with the inspection means for detecting the other portion. Set it low.

  In the eleventh aspect, the inspection object is a steel material induction-hardened, and measures the quenching depth and hardness of the inspection object.

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

  According to the present invention, even an inspection object whose outer diameter changes can be inspected with high inspection accuracy regardless of the measurement site. Can also be applied to the quenching depth / hardness measurement test.

Schematic which shows the structure of the eddy current type | formula inspection apparatus which concerns on 1st embodiment of this invention. (A) is a front view of the ring-shaped eddy current sensor which concerns on 1st embodiment of this invention, (b) is a front view of the state which similarly slid the ring-shaped eddy current sensor. (A) is a front view of a ring-shaped eddy current sensor when the inspection object has a large diameter, (b) is a front view of the ring-shaped eddy current sensor when the inspection object has a normal diameter, and (c) is an inspection object. The front view of a ring-shaped eddy current sensor in the case of a small diameter. The front view which showed the operating state of the detection coil in the ring-shaped eddy current sensor which concerns on 1st embodiment of this invention. (A) is a front view showing the operating state of the ring-shaped eddy current sensor when the inspection object has a large diameter, and (b) shows the operating state of the ring-shaped eddy current sensor when the inspection object has a normal diameter. Front view, (c) is a front view showing the operating state of the ring-shaped eddy current sensor when the inspection object has a small diameter. (A) is the figure which showed the relationship between the penetration depth of the magnetic flux in the case of measuring the quenching depth of a normal part, and the spread of an eddy current, (b) is the magnetic flux in the case of measuring the quenching depth of both ends with high accuracy. The figure which showed the relationship between the penetration depth of an iron and the spread of an eddy current, (c) is the figure which showed the relationship between the penetration depth of a magnetic flux and the spread of an eddy current when measuring the quenching depth of a center part with high precision . Schematic in the case of performing eddy current type | mold inspection about a crankshaft. The front view which showed the operating state of the exciting coil and the detection coil in the eddy current sensor which concerns on 2nd embodiment of this invention.

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.

[First embodiment]
The outline of the eddy current inspection apparatus according to the first embodiment of the present invention will be described with reference to FIG. In the present embodiment, the inspection object of the eddy current type inspection device 10 is a steel material W that has been induction-hardened, and the eddy current type inspection device 10 measures the quenching depth and hardness of the steel material W. A test shall be conducted. However, the eddy current type inspection apparatus according to the present invention is not applied only to the quenching depth / hardness measurement test. For example, a flaw detection test for detecting a crack such as a crack generated on the surface of the inspection object, or an inspection The present invention can also be used for a foreign material discrimination test for detecting foreign matter contained in an object.
In this specification, for the sake of convenience, the left side in FIG. 1 will be referred to as the front, the right side will be referred to as the rear, and the depth direction in FIG.
In FIG. 1, the steel material W to be inspected is described using a yoke shaft. However, the steel material W is a shaft material member such as a short shaft or a long shaft inboard, or a crankshaft or a camshaft as described later. Can also be an inspection object.

  The eddy current inspection apparatus 10 is configured to generate an eddy current in the steel material W, detect the eddy current, and output a value for evaluating the quenching depth and hardness of the steel material W. Further, an evaluation device 13 for evaluating the quenching depth and hardness of the steel material W based on the output value from the eddy current inspection device 10 is electrically connected to the eddy current inspection device 10.

  As shown in FIG. 1, the eddy current type inspection device 10 is electrically connected to three ring-shaped eddy current sensors 21, 22, 23, which are inspection means, and the ring-shaped eddy current sensors 21, 22, 23, respectively. And a jig 15 that holds the ring-shaped eddy current sensors 21, 22, and 23 so as to be movable in the vertical, horizontal, and longitudinal directions. The number of the ring-shaped eddy current sensors 21, 22, and 23 is not limited to three, and a plurality of ring-shaped eddy current sensors 21, 22, and 23 may be used.

As shown in FIGS. 2A and 2B, ring-shaped eddy current sensors 21, 22, and 23 are provided with ring-shaped excitation coils 41, 42, and 43, respectively. Further, as shown in FIG. 4, each of the ring-shaped eddy current sensors 21, 22, and 23 includes a plurality of detection coil blocks 31, 31, 31,..., 32, 32, and 32 along the circumferential direction. , 33, 33, 33 (hereinafter referred to as detection coil blocks 31, 32, 33) are arranged.
In other words, it can be said that the ring-shaped eddy current sensors 21, 22, and 23 are formed in a ring shape by connecting both ends of the rod-shaped member. Ring-shaped exciting coils 41, 42, 43 are disposed along the circumferential direction), and a plurality of detection coil blocks 31, 32, 33 are disposed along the length direction (circumferential direction). ing.
In the present embodiment, each of the ring-shaped eddy current sensors 21, 22, and 23 is provided with 16 detection coil blocks 31, 32, and 33. Coils such as solenoid coils, pancake coils, and planar coils are used for the detection coil blocks 31, 32, and 33.

  The sensor body 11 generates an alternating magnetic field by causing an alternating current to flow through the exciting coils 41, 42, and 43, and also receives detection signals of the induced magnetic fields detected by the detection coil blocks 31, 32, and 33, and detects these detection signals. A value based on the difference between is output. The sensor body 11 is configured to receive or block the detection signals from the detection coil blocks 31, 32, and 33 for each of the detection coil blocks 31, 32, and 33.

  The evaluation device 13 is a so-called electronic computer provided with storage means, calculation means, input means, output means, etc. (not shown), and is electrically connected to the sensor body 11. And while controlling the operation | movement of the eddy current type inspection apparatus 10 by instruct | indicating the sensor main body 11 by the evaluation apparatus 13, the output value from the sensor main body 11 is received, and it compares with the preset threshold value, and steel material W The quality of quenching depth and hardness is evaluated.

  The ring-shaped eddy current sensors 21, 22, and 23 generate an alternating magnetic field when an alternating current flows through the exciting coils 41, 42, and 43 as described above. For example, as shown by an arrow α in FIG. 2A, at the moment when a current flows in a direction opposite to the clockwise direction, a magnetic field is generated in the forward direction of the paper inside the ring-shaped eddy current sensor 21, A magnetic field is generated in the depth direction of the paper on the outside.

  Each of the ring-shaped eddy current sensors 21, 22, and 23 is configured to be able to change the mutual positional relationship by a slide mechanism provided in the jig 15. Specifically, as shown in FIG. 2B, the respective ring-shaped eddy current sensors 21, 22, and 23 are slid vertically and horizontally by shifting the phase by 120 degrees. Thereby, the measurement part R is formed in the overlapping part (part which becomes an inner side with respect to all the ring-shaped eddy current sensors 21, 22, and 23) of the ring-shaped eddy current sensors 21, 22, and 23. In addition, the direction in which each ring-shaped eddy current sensor 21, 22, 23 is slid is not limited to one direction, but can be slid to any place in the vertical and horizontal directions by the slide mechanism provided in the jig 15. And

And the eddy current type | mold inspection apparatus 10 which concerns on this embodiment is an inner side with respect to all the ring-shaped eddy current sensors 21,22,23 among the parts which combine and divide the ring-shaped eddy current sensors 21,22,23 as mentioned above. An alternating magnetic field is generated by passing an alternating current through the exciting coils 41, 42, and 43 in a state where the steel material W, which is an induction-hardened component, is inserted into the measuring section R as shown in FIGS. 1 and 2B. The eddy current is generated in the steel material W by the alternating magnetic field. The induction magnetic field induced by the eddy current is detected by the detection coil blocks 31, 32, and 33, and the quenching depth and hardness of the steel material W are measured. Each of the ring-shaped eddy current sensors 21, 22, and 23 is moved in the front-rear direction by the slide mechanism provided in the jig 15 in a state where the steel material W is inserted into the measuring portion R as shown in FIG. The quenching depth and hardness of W are measured.
The jig 15 is also provided with a function of supporting the steel material W inserted through the measuring portion R so that the ring-shaped eddy current sensors 21, 22, and 23 and the steel material W are substantially coaxial. ing.

  In the present embodiment, the ring-shaped eddy current sensors 21, 22, and 23, which are inspection means, are used. However, the inspection means is not limited to the ring shape, and is a curved or linear shape. The measuring portion R can be formed by other shapes such as a U shape and a V shape.

  Further, the ring-shaped eddy current sensors 21, 22, and 23 in the present embodiment are configured to cause an alternating current to flow through the exciting coils 41, 42, and 43 so that eddy currents in the same direction are generated in the steel material W. Yes. Specifically, as indicated by arrows α, β, and γ in FIG. 2B, currents flow in the same direction (counterclockwise in FIG. 2B) to the respective ring-shaped eddy current sensors 21, 22, and 23. As a result, an alternating magnetic field is generated in the same direction in the measurement part R, and an eddy current flows in the same direction in the steel material W at each moment. That is, a strong magnetic field is formed in the measurement unit R by aligning the direction of the current flowing through the ring-shaped eddy current sensors 21, 22, and 23.

  Furthermore, the ring-shaped eddy current sensors 21, 22, and 23 in the present embodiment use the slide mechanism provided in the jig 15 according to the diameter of the steel material W, and the positional relationship between the ring-shaped eddy current sensors 21, 22, and 23 is used. The size of the measurement part R can be changed by changing. Specifically, as shown in FIG. 3A, when inspecting a large-diameter steel material W1, the measurement portion R is formed larger by increasing the mutual overlap of the ring-shaped eddy current sensors 21, 22, and 23. It is. On the other hand, in the case of the steel material W2 having a normal diameter and the steel material W2 having a small diameter, as shown in FIGS. 3B and 3C, the mutual overlap of the ring-shaped eddy current sensors 21, 22, 23 is gradually reduced. By doing so, the measuring part R is made smaller.

  That is, by changing the size of the measurement part R in accordance with the outer diameter of the steel material W, the filling factor of the measurement site in the measurement part R according to the outer diameter of the steel material W (relative to the inner peripheral cross-sectional area of the measurement part R) The ratio of the cross-sectional area of the measurement site) can be changed. That is, even if the outer diameter of the steel material W is reduced, the measurement rate R is not reduced and the measurement accuracy is not deteriorated by forming the measurement portion R to be small accordingly. In other words, regardless of the outer diameter of the steel material W, the quenching depth and hardness can be accurately measured with high inspection accuracy.

  Further, as shown in FIG. 4, a plurality of the detection coil blocks 31, 32, and 33 are disposed along the inside of the ring-shaped eddy current sensors 21, 22, and 23 in the present embodiment. The detection coil blocks 31, 32, and 33 of the ring-shaped eddy current sensors 21, 22, and 23 forming the measurement unit R (shaded portions in FIG. 4) are configured to detect the induction magnetic field. ing.

  Specifically, detection signals from detection coil blocks 31a, 32a, and 33a (hereinafter referred to as invalid coil blocks 31a, 32a, and 33a) of the ring-shaped eddy current sensors 21, 22, and 23 that are not adjacent to the measurement unit R. Is not received by the sensor body 11, and only the detection signals from the detection coil blocks 31b, 32b, and 33b (hereinafter referred to as effective coil blocks 31b, 32b, and 33b) adjacent to the measurement unit R are received by the sensor body. 11 is received. That is, the sensor main body 11 is controlled such that the ineffective coil blocks 31a, 32a, and 33a do not detect the induction magnetic field, and the effective coil blocks 31b, 32b, and 33b detect the induction magnetic field.

  And when the magnitude | size of the said measurement part R is changed according to the outer diameter of the steel W as mentioned above, the invalid coil block 31a * 32a * 33a and the effective coil block 31b * 32b * 33b are made into the magnitude | size of the measurement part R. Switching is made accordingly. Specifically, as shown in FIG. 5 (a), when the measuring portion R is formed large in order to inspect the steel material W1 having a large diameter, the invalid coil block 31a. The sensor body 11 is controlled so as to increase the ratio of the effective coil blocks 31b, 32b, and 33b that receive the detection signal by the sensor body 11 with respect to 32a and 33a.・ Enclose with 32b and 33b. In FIG. 5A, the number of invalid coil blocks 31a, 32a, and 33a is ten, whereas the number of effective coil blocks 31b, 32b, and 33b is six.

  On the other hand, when the measurement part R is formed small in order to inspect the steel material W2 having a normal diameter and the steel material W3 having a small diameter, the size of the measurement part R is large as shown in FIGS. 5 (b) and 5 (c). Accordingly, the effective coil blocks 31b, 32b, and 33b are switched to the invalid coil blocks 31a, 32a, and 33a. In FIG. 5B, the number of invalid coil blocks 31a, 32a, and 33a is twelve, whereas the number of effective coil blocks 31b, 32b, and 33b is four. In FIG. 5 (c), the number of invalid coil blocks 31a, 32a, and 33a is 14, whereas the number of effective coil blocks 31b, 32b, and 33b is two.

  By configuring as described above, it is possible to prevent the induction magnetic field from being detected in portions other than the vicinity of the measurement portion R in the ring-shaped eddy current sensors 21, 22, and 23. That is, by detecting the induction magnetic field of only the measurement unit R necessary for the eddy current type inspection, it is possible to reduce the influence of disturbance or the like in the induction magnetic field to be detected, and to improve the inspection accuracy.

In addition, as described above, the ring-shaped eddy current sensors 21, 22, and 23 have a configuration in which a plurality of the detection coil blocks 31, 32, and 33 are disposed along the inside thereof, so that the shape of the steel material W can be changed. It becomes possible to control the detection of the induction magnetic field of the detection coil blocks 31, 32, and 33.
Specifically, for example, when the induction magnetic field to be detected is affected because a hole is opened in a part of the steel material W, the portions corresponding to the hole are ineffective coil blocks 31a, 32a, and 33a. As a result, the sensor body 11 can be configured not to receive the detection signal. Thereby, since it can prevent that a noise component appears in a detection result by the shape of steel materials W like the said hole, it becomes possible to improve inspection accuracy.
Similarly, the invalid coil blocks 31a, 32a and 33a and the effective coil blocks 31b, 32b and 33b can be switched in accordance with the quenching depth of the steel material W.

  Furthermore, in the eddy current type inspection, if the frequency of the alternating current that flows through the exciting coil (hereinafter referred to as the exciting frequency) is set high, the spread of the eddy current becomes wide but the penetration depth of the magnetic flux becomes shallow. Is set low, the spread of the eddy current is narrowed but the penetration depth of the magnetic flux is deep. For this reason, in the ring-shaped eddy current sensors 21, 22, and 23, the portions to be inspected with high accuracy in the steel material W are configured to set the excitation frequency of the excitation coils 41, 42, and 43 relatively low. .

Specifically, when measuring the quenching depth in the widest possible range on average, the excitation frequency is set low in the ring-shaped eddy current sensors 21, 22, and 23, and the entire magnetic flux as shown in FIG. It is measured by increasing the penetration depth. 6 (a) to 6 (c) show the relationship between the penetration depth of magnetic flux and the spread of eddy current when quenching depth is measured by ring-shaped eddy current sensors 21, 22, and 23 in order from the left. It is a figure.
On the other hand, when the quenching depth at both ends is measured with high accuracy, the excitation frequency of the ring-shaped eddy current sensors 21, 23 at both ends of the ring-shaped eddy current sensors 21, 22, 23 is set to Measurement is performed by setting the excitation frequency lower than the excitation frequency and increasing the penetration depth of the magnetic flux at both ends as shown in FIG. On the other hand, when the quenching depth at the center is measured with high accuracy, the excitation frequency of the ring-shaped eddy current sensor 22 at the center of the ring-shaped eddy current sensors 21, 22, 23 is set to the ring-shaped eddy current sensor 21. The measurement is performed by setting the excitation frequency lower than 23 and increasing the penetration depth of the magnetic flux at the center as shown in FIG.
By comprising as mentioned above, it becomes possible to measure the quenching depth according to the required inspection accuracy in the steel material W.

  In addition, since each ring-shaped eddy current sensor 21,22,23 can be slid to arbitrary places of the up-down, left-right direction, the ring-shaped eddy current sensors 21,22 in the measurement part R according to the shape and measurement conditions of a measurement location. -It is set as the structure which can change the positional relationship of 23. That is, it is possible to perform measurement by setting any one of the ring-shaped eddy current sensors 21, 22, and 23 close to the portion of the steel material W that is desired to be measured with the highest accuracy and setting the excitation frequency relatively low.

  Even when the eddy current inspection apparatus 10 according to the present invention is applied to a flaw detection test or a different material discrimination test, the excitation frequencies of the excitation coils 41, 42, and 43 are set relatively low in the ring-shaped eddy current sensors 21, 22, and 23. By doing so, it becomes possible to inspect deeper portions of the inspection object.

Next, a method for performing eddy current inspection on a crankshaft as a steel material W that is an inspection object using the eddy current inspection device 10 according to the present embodiment will be described with reference to FIG.
In the eddy current type inspection apparatus 10 according to the present embodiment, the size of the measuring unit R can be changed by changing the mutual positional relationship between the ring-shaped eddy current sensors 21, 22, and 23 according to the diameter of the steel material W. It is configured. For this reason, as shown in FIG. 7, the size of the measurement portion R is also obtained in a crankshaft configured by connecting a plurality of journal portions and a plurality of pin portions having a smaller diameter than the journal portions, respectively, by arm portions. It is possible to measure the quenching depth and hardness of the crankshaft by changing according to the diameter of the journal part or the pin part.

  That is, as shown in FIG. 7, when the eddy current type inspection is performed on the journal part and the pin part, the position of the ring-shaped eddy current sensors 21, 22, 23 is shifted to reduce the size of the measuring part R, and the arm part is formed. When passing, the ring-shaped eddy current sensors 21, 22, and 23 are aligned. As described above, by performing the eddy current inspection in the order of the measurement directions indicated by the arrows in FIG. 7, it is possible to inspect a component whose outer diameter changes greatly, such as a crankshaft.

Even in this case, the ineffective coil blocks 31a, 32a, 33a and the effective coil blocks 31b, 32b, 33b are switched according to the size of the measuring part R, so that the measurement in the ring-shaped eddy current sensors 21, 22, 23 is performed. The induction magnetic field can be prevented from being detected in portions other than the vicinity of the portion R. As a result, it is possible to reduce the influence of disturbance or the like in the induced magnetic field detected by the journal portion or the pin portion of the crankshaft, so that the inspection accuracy can be improved.
The same applies to the case where the present embodiment is applied to other parts such as a camshaft as the inspection object.

  As described above, the eddy current inspection method according to the present embodiment includes three ring-shaped eddy current sensors 21 in which the excitation coils 41, 42, 43 and the plurality of detection coil blocks 31, 32, 33 are disposed. In the state where the steel material W is inserted into the measurement part R which is inside with respect to all the ring-shaped eddy current sensors 21, 22, and 23 among the parts divided by combining 22 and 23, the excitation coils 41, 42 and 43 An alternating magnetic field is generated inside the measurement unit R by passing an alternating current. Then, an eddy current is generated in the steel material W by the AC magnetic field, and the induction magnetic field induced by the eddy current is detected by the detection coil blocks 31, 32, and 33. Furthermore, the size of the measurement part R is changed and the ring-shaped eddy current is changed by changing the mutual positional relationship in the three ring-shaped vortex flow sensors 21, 22, and 23 according to the diameter of the steel material W. The detection coil blocks 31, 32, and 33 of the sensor 21, 22, and 23 that form the measurement unit R detect the induced magnetic field.

  By configuring as described above, it is possible to prevent the induction magnetic field from being detected in portions other than the vicinity of the measurement portion R in the ring-shaped eddy current sensors 21, 22, and 23. That is, by detecting the induction magnetic field of only the measurement unit R necessary for the eddy current type inspection, it is possible to reduce the influence of disturbance or the like in the detected induction magnetic field, and to improve the inspection accuracy.

  Further, by flowing an alternating current through the exciting coils 41, 42, 43 so that an eddy current in the same direction is generated in the steel material W, the direction of the current flowing through the ring-shaped eddy current sensors 21, 22, 23 is aligned and measured. A strong magnetic field can be formed in the portion R.

  Further, in the ring-shaped eddy current sensors 21, 22, and 23 that detect a portion of the steel material W to be inspected with high accuracy, the excitation coils 41 and 42 are more than the ring-shaped eddy current sensors 21, 22, and 23 that detect other portions. -The frequency of the alternating current flowing through 43 is set relatively low. Thereby, the quenching depth can be measured according to the required inspection accuracy in the steel material W.

  As described above, the eddy current inspection method according to this embodiment can inspect even an inspection object whose outer diameter changes with high inspection accuracy regardless of the measurement site. Even in the case of inspecting a steel material W that is an induction-hardened component whose diameter changes greatly, it can be applied to a quenching depth / hardness measurement test.

[Second Embodiment]
Next, an eddy current inspection apparatus according to a second embodiment of the present invention will be described with reference to FIG. In the eddy current type inspection apparatus described in the present embodiment, the description of the parts common to the above-described embodiment is omitted.

  Also in this embodiment, as in the previous embodiment, the inspection object of the eddy current type inspection device is a steel material W that has been induction-hardened, and the eddy current type inspection device measures the quenching depth and hardness of the steel material W. A thickness / hardness measurement test shall be performed.

As shown in FIG. 8, the eddy current type inspection apparatus according to the present embodiment includes three U-shaped eddy current sensors 121, 122, and 123 that are inspection means. Each of the U-shaped eddy current sensors 121, 122, 123 includes a plurality of exciting coil blocks 141, 141, 141, 142, 142, 142,. 143, 143 (hereinafter referred to as excitation coil blocks 141, 142, 143) and a plurality of detection coil blocks 131, 131, 131, 132, 132, 132,. 133, 133... (Hereinafter referred to as detection coil blocks 131, 132, 133) are arranged.
That is, the U-shaped eddy current sensors 121, 122, and 123 are provided with a plurality of exciting coil blocks 141, 142, and 143 along the length direction, and a plurality of detection coil blocks along the length direction. It can be said that the rod-shaped member provided with 131, 132, 133 is formed in a U shape.
In this embodiment, the U-shaped eddy current sensors 121, 122, and 123 have nine exciting coil blocks 141, 142, and 143 on the inner peripheral side, and nine detection coil blocks 131, 132, and 123 on the outer peripheral side. 133 is disposed. Coils such as solenoid coils, pancake coils, and planar coils are used for the excitation coil blocks 141, 142, and 143 and the detection coil blocks 131, 132, and 133.

  A sensor body (not shown) causes an alternating current to flow through the excitation coil blocks 141, 142, and 143 to generate an alternating magnetic field, and receives a detection signal of the induction magnetic field detected by the detection coil blocks 131, 132, and 133, A value based on the difference between these detection signals is output. The sensor main body is configured to allow an alternating current to flow or to be cut off for each of the exciting coil blocks 141, 142, and 143. The sensor main body is configured to receive or block the detection signals from the detection coil blocks 131, 132, 133 for each of the detection coil blocks 131, 132, 133.

  And the eddy current type | mold inspection apparatus which concerns on this embodiment adds to all the U-shaped eddy current sensors 121 * 122 * 123 among the parts which divide and combine the curved part of U-shaped eddy current sensors 121 * 122 * 123 as mentioned above. On the other hand, in the state where the steel material W, which is an induction hardened part, is inserted as shown in FIG. An eddy current is generated in the steel material W by the alternating magnetic field. The induction magnetic field induced by the eddy current is detected by the detection coil blocks 131, 132, and 133, and the quenching depth and hardness of the steel material W are measured.

  Further, along the inside of the U-shaped eddy current sensor 121, 122, 123 in the present embodiment, as shown in FIG. 8, a plurality of the excitation coil blocks 141, 142, 143 and the detection coil blocks 131, 132, 133 are provided. It is arranged. The exciting coil blocks 141, 142, and 143 of the U-shaped eddy current sensors 121, 122, and 123 that form the measurement portion R (shaded portions in FIG. 8) pass an alternating current, The detection coil blocks 131, 132, and 133 of the portions forming the measurement portion R (shaded portions in FIG. 8) of the eddy current sensors 121, 122, and 123 are configured to detect the induced magnetic field.

Specifically, portions of the U-shaped eddy current sensors 121, 122, and 123 that are not adjacent to the measurement unit R have excitation coil blocks 141a, 142a, and 143a (hereinafter referred to as invalid excitation coil blocks 141a, 142a, and 143a). AC current from the sensor body is cut off, and the excitation coil blocks 141b, 142b, and 143b (hereinafter referred to as effective excitation coil blocks 141b, 142b, and 143b) adjacent to the measurement unit R are supplied with AC current from the sensor body. It flows.
The detection signals from the detection coil blocks 131a, 132a, and 133a (hereinafter referred to as invalid detection coil blocks 131a, 132a, and 133a) of the U-shaped eddy current sensors 121, 122, and 123 that are not adjacent to the measurement unit R are The sensor body receives only detection signals from the detection coil blocks 131b, 132b, and 133b (hereinafter referred to as effective detection coil blocks 131b, 132b, and 133b) adjacent to the measurement unit R without being received by the sensor body. To do. That is, only the effective excitation coil blocks 141b, 142b, and 143b pass an alternating current, and only the effective detection coil blocks 131b, 132b, and 133b detect the induction magnetic field.

  Moreover, when the magnitude | size of the measurement part R is changed according to the outer diameter of steel materials like the said embodiment, the invalid excitation coil block 141a * 142a * 143a and the effective excitation coil block 141b * 142b * 143b are measured. At the same time as switching according to the size of R, the invalid detection coil blocks 131a, 132a, and 133a and the valid detection coil blocks 131b, 132b, and 133b are switched according to the size of the measurement unit R.

  With the configuration as described above, it is possible to reduce the influence of disturbances or the like in the induced magnetic field to be detected by flowing an alternating current only through the measurement unit R necessary for the eddy current type inspection and detecting the induced magnetic field, and the inspection accuracy. It becomes possible to improve.

Further, as described above, the U-shaped eddy current sensors 121, 122, and 123 are configured such that a plurality of the excitation coil blocks 141, 142, and 143 and the detection coil blocks 131, 132, and 133 are disposed along the inside. Accordingly, it is possible to control the conduction of the alternating current to the exciting coil blocks 141, 142, and 143 and the detection of the induction magnetic field of the detection coil blocks 131, 132, and 133 in accordance with the shape of the steel material W and the like.
Specifically, for example, in the portion where the quenching depth is measured with high accuracy, the excitation frequency of the excitation coil blocks 141, 142, and 143 is set lower than the other portions and is measured. By comprising in this way, it becomes possible to measure the quenching depth according to the required inspection accuracy in the steel material W.

  As described above, the eddy current inspection method according to the present embodiment includes three U coil units 141, 142, and 143 and a plurality of detection coil blocks 31, 32, and 33 arranged therein. In the state where the steel material W is inserted into the measuring part R which is inside of all the U-shaped eddy current sensors 121, 122, 123 among the parts partitioned by combining the character-shaped eddy current sensors 121, 122, 123, the excitation coil An AC magnetic field is generated inside the measurement unit R by passing an AC current through the blocks 141, 142, and 143. Then, an eddy current is generated in the steel material W by the AC magnetic field, and the induction magnetic field induced by the eddy current is detected by the detection coil blocks 131, 132, and 133. Furthermore, according to the diameter of the said steel material W, while changing the magnitude | size of the said measurement part R by changing the mutual positional relationship in the said three U-shaped eddy current sensors 121 * 122 * 123, it is U-shaped. The excitation coil blocks 141, 142, and 143 that form the measurement unit R of the eddy current sensors 121, 122, and 123 pass an alternating current, and the measurement unit R of the U-shaped eddy current sensors 121, 122, and 123 The detection coil blocks 131, 132, and 133 in the portion that forms the line detect the induction magnetic field.

  With the configuration as described above, it is possible to reduce the influence of disturbances or the like in the induced magnetic field to be detected by flowing an alternating current only through the measurement unit R necessary for the eddy current type inspection and detecting the induced magnetic field, and the inspection accuracy. It becomes possible to improve.

DESCRIPTION OF SYMBOLS 11 Sensor main body 21 Ring-shaped eddy current sensor 22 Ring-shaped eddy current sensor 23 Ring-shaped eddy current sensor 31 Detection coil block 32 Detection coil block 33 Detection coil block 41 Excitation coil 42 Excitation coil 43 Excitation coil

Claims (11)

A plurality of rod-shaped inspection means having an excitation coil and a detection coil disposed therein,
The measurement unit is configured by passing an alternating current through the excitation coil in a state in which an inspection object is inserted into a measurement unit that is inside with respect to all of the inspection units among the sections that are divided by combining the plurality of inspection units. An eddy current type inspection device that generates an alternating magnetic field, generates an eddy current in the inspection object by the alternating magnetic field, and detects an induced magnetic field induced by the eddy current by the detection coil,
According to the diameter of the inspection object, by changing the mutual positional relationship in the plurality of inspection means, the size of the measurement unit can be changed,
The detection coil is configured by arranging a plurality of detection coil blocks along the length direction of the inspection means,
Among the inspection means, said detection coil block measurement unit and the adjacent portions detects the induced magnetic field by the detection coil block area which is not adjacent to the measurement portion is configured so as not to detect the induced magnetic field The region for detecting the induction magnetic field in the inspection unit is switched according to the size of the measurement unit.
An eddy current inspection device characterized by the above. As the plurality of inspection means, three ring eddy current sensors are provided.
The eddy current type inspection apparatus according to claim 1, wherein: The excitation coil is configured by arranging a plurality of excitation coil blocks along the length direction of the inspection means,
The excitation coil block of the part that forms the measurement part of the inspection means is configured to flow the alternating current ,
Among the inspecting means, the excitation coil block measurement unit and the adjacent portion is the flow of the alternating current, by the excitation coil block area which is not adjacent to the measurement portion is configured so as not to flow the alternating current The region in which the alternating current flows in the inspection unit is switched according to the size of the measurement unit.
The eddy current type inspection apparatus according to claim 1, wherein: An alternating current is passed through the exciting coil so that eddy currents in the same direction are generated in the inspection object.
The eddy current type inspection apparatus according to any one of claims 1 to 3, wherein In the inspection means for detecting the part to be inspected with high accuracy of the inspection object, the frequency of the alternating current flowing through the exciting coil is set relatively lower than the inspection means for detecting the other part.
The eddy current type inspection apparatus according to any one of claims 1 to 4, wherein The inspection object is a steel material induction-hardened,
Measure the quenching depth and hardness in the inspection object,
The eddy current type inspection apparatus according to any one of claims 1 to 5, wherein In the state where the inspection object is inserted into the measuring part that is on the inner side with respect to all the inspection means among the parts that are divided by combining a plurality of inspection means in which the excitation coil and the detection coil are arranged, the excitation An AC magnetic field is generated in the measurement unit by flowing an AC current through the coil, an eddy current is generated in the inspection object by the AC magnetic field, and an induction magnetic field induced by the eddy current is detected by the detection coil; An eddy current inspection method,
According to the diameter of the inspection object, by changing the mutual positional relationship in the plurality of inspection means, to change the size of the measurement unit,
The detection coil is configured by arranging a plurality of detection coil blocks along the length direction of the inspection means,
Among the inspecting means, by detection coil block portion adjacent to the measuring unit detects the induced magnetic field, the detection coil block portion which is not adjacent to the measurement unit does not detect the induced magnetic field, in the examination means Switch the region for detecting the induced magnetic field according to the size of the measurement unit,
An eddy current inspection method characterized by the above. The excitation coil is configured by arranging a plurality of excitation coil blocks along the length direction of the inspection means,
Exciting coil block of the part forming the measurement portion is flow to the alternating current of said inspection means,
Among the inspecting means, by the exciting coil block portion adjacent to the measuring unit to flow the alternating current, the excitation coil block portion which is not adjacent to the measuring portion does not flow the alternating current, in said inspection means Switching the region in which the alternating current flows according to the size of the measurement unit,
The eddy current inspection method according to claim 7, wherein: An alternating current is passed through the exciting coil so that eddy currents in the same direction are generated in the inspection object.
The eddy current inspection method according to claim 7 or claim 8, wherein In the inspection means for detecting the part to be inspected with high accuracy of the inspection object, the frequency of the alternating current flowing through the exciting coil is set relatively lower than the inspection means for detecting the other part.
The eddy current inspection method according to any one of claims 7 to 9, wherein The inspection object is a steel material induction-hardened,
Measure the quenching depth and hardness in the inspection object,
The eddy current inspection method according to any one of claims 7 to 10, wherein

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