JP6288640B2 - Eddy current flaw detection probe, eddy current flaw detection apparatus, and eddy current flaw detection method - Google Patents

Description

  The present invention relates to an eddy current testing probe, an eddy current testing device, and an eddy current testing method.

An eddy current flaw detection method is known as a method for nondestructively inspecting defects such as flaws and thinning in pipes. Several techniques have been proposed in connection with this eddy current flaw detection method.
For example, Patent Document 1 includes a non-contact and non-magnetic distance sensor that transmits and receives light to an eddy current flaw detection coil, and a signal obtained from the distance sensor is simultaneously measured with an eddy current flaw detection signal, resulting in lift-off. It is described that the eddy current flaw detection signal is corrected and separated from the eddy current flaw detection signal due to flaws and material changes. Further, in Patent Document 1, when there are a plurality of distance sensors provided in the eddy current flaw detection coil, the coil inclination 7 can be calculated by calculating a signal obtained by each distance sensor, and a highly accurate eddy current flaw detection signal is obtained. Correction is possible.

JP 2006-138784 A

In the conventional eddy current flaw detection, when a local defect and a wide-area defect are mixed in a flaw detection target, it is difficult to accurately measure the depth of both defects. In particular, when a local defect and a wide-area defect in which the depth of the defect gradually changes are mixed in the inspection target, it is difficult to accurately measure the depth of both defects.
For example, in the differential method, a difference between signals in two adjacent coils is obtained. By taking the signal difference, the differential method can cancel the influence of temperature or the like and measure the local defect depth with high accuracy. On the other hand, when the differential method is applied to a wide-range defect in which the depth of the defect changes gradually, the difference between the signals of the two coils becomes small, and it is difficult to measure the depth of the defect with high accuracy.

  The present invention can measure the depth of both defects more accurately even when a local defect and a wide-range defect in which the depth of the defect gradually changes are mixed in the test object. An eddy current testing probe, an eddy current testing device, and an eddy current testing method are provided.

In the eddy current flaw detection probe according to the first aspect of the present invention, a probe main body in which a plurality of cross coils obtained by combining a plurality of coils wound around different axes intersecting each other and a plurality of the plurality of cross coils constituting each cross coil are configured. differential mode respectively supply and current supply unit capable of supplying a current to the coil, by the previous SL current supply unit switches the connection to the coil, the current in each of said plurality of coils constituting each cross coil And a switch for switching between an absolute mode in which current flows only in one of the plurality of coils constituting each cross, and when a defect is detected in any of the plurality of cross coils in the differential mode, Switch to the absolute mode by switching the connection relation of the switch And flaw detection method switching unit that comprises a.

In the eddy current flaw detector according to the second aspect of the present invention, a probe main body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other, and the plurality of cross coils constituting each cross coil differential mode respectively supply and current supply unit capable of supplying a current to the coil, by the previous SL current supply unit switches the connection to the coil, the current in each of said plurality of coils constituting each cross coil A switch for switching the absolute mode in which current flows only through one coil per cross coil, a detection unit for detecting the impedance of the coil in each cross coil, and the plurality of crosses in the differential mode. One of the coils is missing based on the impedance. There comprising when it is detected, and a flaw detection method switching unit to switch to the absolute mode by switching the connection relationship of the switch.

A storage unit for storing a plurality of depth acquisition information indicating the relationship between the magnitude of the impedance detected by the detection unit and the depth of a defect in the flaw detection target, and the adjacent one of the plurality of cross coils in the absolute mode. Depth for selecting depth acquisition information for a wide area defect when a defect is detected in a predetermined number or more of cross coils, otherwise selecting depth acquisition information for a local defect An acquisition information selection unit; and a depth acquisition unit that obtains the depth of a defect in the flaw detection target from the detection result of the detection unit using the depth acquisition information selected by the depth acquisition information selection unit. You may make it comprise.
One of the plurality of cross coils in the absolute mode, a storage unit for storing a plurality of depth acquisition information indicating the relationship between the magnitude of the impedance detected by the detection unit and the depth of the defect in the flaw detection target If a defect is detected in the adjacent cross coil and the adjacent cross coil, and the signal amplitude in the adjacent cross coil is 50% or more of the signal amplitude in the central cross coil, the depth acquisition for a wide area defect is obtained. A depth acquisition information selection unit that selects information, otherwise selects depth acquisition information for local defects, and the depth acquisition information selected by the depth acquisition information selection unit. And a depth acquisition unit that obtains the depth of the defect in the flaw detection target from the detection result of the detection unit.

In the eddy current flaw detection method according to the third aspect of the present invention, a probe main body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other, and the plurality of cross coils constituting each cross coil, differential mode respectively supply and current supply unit capable of supplying a current to the coil, by the previous SL current supply unit switches the connection to the coil, the current in each of said plurality of coils constituting each cross coil An eddy current flaw detector comprising: a switch that switches between an absolute mode in which current flows only through one of the plurality of coils that constitute each cross; and a detection unit that detects the impedance of the coil in each cross coil a eddy current testing method using a plurality of Kurosukoi in the differential mode In either, if a defect is detected on the basis of the impedance, it has a flaw detection method switching step of switching to the absolute mode by switch the connection relationship of the switch.

In the eddy current flaw detection method according to the fourth aspect of the present invention, a probe main body in which a plurality of cross coils obtained by combining a plurality of coils wound around different axes intersecting with each other and the plurality of cross coils constituting each cross coil are configured. differential mode respectively supply and current supply unit capable of supplying a current to the coil, by the previous SL current supply unit switches the connection to the coil, the current in each of said plurality of coils constituting each cross coil An eddy current flaw comprising: a sswitch that switches between an absolute mode in which current flows only through one of the plurality of coils constituting each cross; and a detection unit that detects the impedance of the coil in each cross coil a eddy current testing method using the apparatus, in the absolute mode, the plurality of Kurosukoi If a defect in a given or more cross adjacent coils is detected among said the size of the impedance detecting unit detects, probe shows a relationship between the depth of the defect in wound subject, a plurality of depth obtaining information A depth acquisition information selection step of selecting depth acquisition information for a wide-area defect, and selecting depth acquisition information for a local defect in the other cases, and the depth acquisition information A depth acquisition step of obtaining the depth of the defect in the flaw detection target from the detection result of the detection unit using the depth acquisition information selected in the selection step.

  According to the eddy current flaw detection probe, the eddy current flaw detection apparatus, and the eddy current flaw detection method described above, even when a local defect and a wide-area defect in which the depth of the defect gently changes are mixed in the flaw detection target, The depth of the defect can be measured with higher accuracy.

It is a schematic block diagram which shows the function structure of the eddy current flaw detector in one Embodiment of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the cross coil in a probe main body. It is explanatory drawing which shows the 1st example of the connection state of a cross coil and an electric current supply part. It is explanatory drawing which shows the example of the local defect in the cross section of piping. It is explanatory drawing which shows the example of the local defect in the longitudinal cross-section of piping. It is explanatory drawing which shows the example of the wide defect in the cross section of piping. It is explanatory drawing which shows the example of the wide area defect in the longitudinal cross-section of piping. It is explanatory drawing which shows the example of the detected value by the differential system in a wide area defect. It is explanatory drawing which shows the 2nd example of the connection state of a cross coil and an electric current supply part. It is explanatory drawing which shows the example of the information for depth acquisition in an absolute mode which a memory | storage part memorize | stores. It is a flowchart which shows the process sequence which an eddy current flaw detector performs an eddy current flaw. It is a flowchart which shows the procedure of the process which an eddy current flaw detector performs for every sampling in differential mode. It is a flowchart which shows the procedure of the process which an eddy current flaw detector performs for every sampling in absolute mode.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.
FIG. 1 is a schematic block diagram showing a functional configuration of an eddy current flaw detector according to an embodiment of the present invention. In FIG. 1, an eddy current flaw detector 1 includes an eddy current flaw probe 100 and an eddy current flaw detector main body 200. The eddy current flaw detection probe 100 includes a probe main body 110 in which a plurality of cross coils 111 are arranged, a switch 120, and a current supply unit 130. Each of the cross coils 111 includes a peripheral coil 112 and a shaft coil 113. The eddy current flaw detector main body 200 includes a display unit 210, an operation input unit 220, a storage unit 280, and a control unit 290. The control unit 290 includes a detection unit 291, a flaw detection method switching unit 292, a depth acquisition information selection unit 293, and a depth acquisition unit 294.

The eddy current flaw detection apparatus 1 detects flaws and thinning of a flaw detection target by eddy current flaw detection. Hereinafter, scratches and thinning are collectively referred to as “defects”.
In the present embodiment, the case where the eddy current flaw detector 1 is used for detecting a defect inside the cylindrical pipe will be described as an example, but the application range of the eddy current flaw detector 1 is not limited thereto. The eddy current flaw detector 1 can be used for various flaw detection objects that can carry out eddy current flaw detection.

The eddy current flaw detection probe 100 generates a magnetic field using the cross coil 111, and detects an eddy current generated in the flaw detection target by the magnetic field based on a change in the impedance of the coil in the cross coil 111.
The cross coil 111 is configured by combining a plurality of coils (a circumferential coil 112 and a shaft coil 113) wound around different axes intersecting each other.

The circumferential coil 112 is disposed so that the circumferential direction of the coil matches the circumferential direction of the pipe. Therefore, the circumferential coil 112 is arranged so that the axial direction of the coil is aligned with the longitudinal direction (axial direction) of the pipe.
The axial coil 113 is arranged so that the circumferential direction of the coil is aligned with the longitudinal direction of the pipe. Therefore, in the axial coil 113, the axial direction of the coil is orthogonal to the longitudinal direction of the pipe.

FIG. 2 is an explanatory view showing an arrangement example of the cross coils 111 in the probe main body 110. The figure shows an arrangement example when the probe main body 110 inserted into the pipe 900 to be inspected (flaw detection target) is viewed from the axial direction of the pipe 900.
In the figure, a cross coil 111 is annularly arranged on the probe main body 110 corresponding to the cylindrical shape of the pipe 900. Each of the cross coils 111 includes a peripheral coil 112 and a shaft coil 113.

In addition, the structure of the cross coil 111 is not restricted to the structure which combined the two coils (circumferential coil 112 and axial coil 113) shown to the figure. The cross coil 111 may be configured by combining three or more coils wound around different axes intersecting each other.
In this embodiment, the case where the magnetic field generating coil and the impedance measuring coil are the same will be described as an example. However, in the peripheral coil 112 and the axial coil 113, the magnetic field generating coil and the impedance measuring coil are used. And may be provided separately.

The current supply unit 130 can supply an alternating current to each of the plurality of coils constituting each cross coil 111. More specifically, the current supply unit 130 is connected to either the circumferential coil 112 or the shaft coil 113, or both the circumferential coil 112 and the shaft coil 113, depending on the state of the switch 120. AC current can be supplied.
Note that the power source used by the current supply unit 130 may be located outside the eddy current flaw detector 1 or may be located inside the eddy current flaw detector 1. For example, the current supply unit 130 may include a transformer circuit that receives power supplied from an external power source such as a commercial power source and transforms the voltage into a flaw detection voltage. Alternatively, the current supply unit 130 may include a battery that outputs DC power and a DC / AC conversion circuit that converts the DC power into AC power.

The switch 120 switches the connection between the current supply unit 130 and the coil so that the current is supplied to at least one of the plurality of coils (the peripheral coil 112 and the shaft coil 113) constituting each cross coil 111.
FIG. 3 is an explanatory diagram illustrating a first example of a connection state between the cross coil 111 and the current supply unit 130. In the drawing, one cross coil 111, a current supply unit 130, and a switch among the switches 120 that switch a connection state between the cross coil 111 and the current supply unit 130 are illustrated.
As shown in FIG. 3, each of the peripheral coil 112 and the shaft coil 113 and the current supply unit 130 are wired via the switch 120. With this wiring, the current supply unit 130 can supply an alternating current to each of the plurality of coils (the peripheral coil 112 and the shaft coil 113) constituting each cross coil 111 according to the state of the switch 120.

In the example of FIG. 3, both the switch between the circumferential coil 112 and the current supply unit 130 and the switch between the shaft coil 113 and the current supply unit 130 are in a connected state (ON). In this state, the current supply unit 130 supplies current to both the peripheral coil 112 and the shaft coil 113. Thereby, the eddy current flaw detector 1 performs flaw detection by the differential method.
Hereinafter, the mode in which the eddy current flaw detection apparatus 1 performs flaw detection by the differential method is referred to as “differential mode”.

In the differential method, the difference between the impedance in the peripheral coil 112 and the impedance in the shaft coil 113 is taken. By taking the difference, the influence of temperature or the like (for example, the influence of the change in the resistance value of the coil conductor due to the temperature change) can be canceled, and the depth of the defect can be obtained with higher accuracy.
On the other hand, when the differential method is applied to a wide-range defect in which the depth of the defect changes gently, the difference between the signals of the two coils becomes small, and it is difficult to measure the depth of the defect with high accuracy. This point will be described with reference to FIGS.

FIG. 4 is an explanatory diagram showing an example of local defects in the cross section of the pipe 900. In the drawing, a cross section of the pipe 900 (a cross section perpendicular to the axial direction of the pipe 900) is shown, and a region A11 is a local defect. The local defect referred to here is a defect having a relatively small area or width.
FIG. 5 is an explanatory diagram showing an example of local defects in the longitudinal section of the pipe 900. In the figure, a vertical cross section of the pipe 900 (a cross section parallel to the axial direction of the pipe 900) is shown, and the region A12 is a local defect.

FIG. 6 is an explanatory diagram showing an example of a wide-area defect in the cross section of the pipe 900. In the figure, a cross section of the pipe 900 is shown, and the region A21 is a wide-area defect. The wide-area defect referred to here is a defect having a relatively large area or width.
FIG. 7 is an explanatory diagram showing an example of a wide-area defect in the longitudinal section of the pipe 900. In the figure, a longitudinal section of the pipe 900 is shown, and the region A22 is a wide-area defect.

FIG. 8 is an explanatory diagram showing an example of detection values in the differential method for a wide-area defect. In the figure, a longitudinal section of the pipe 900 is shown, and the region A31 is a wide-area defect. In particular, the depth of the defect in the region A31 changes gently.
In addition, the graph in the figure shows an example of signal amplitude detection values at each position when flaw detection is performed by the differential method while moving the cross coil (for example, the cross coil 111) in the axial direction of the pipe 900. Yes. In this case, for example, the difference between the voltage across the circumferential coil 112 and the voltage across the shaft coil 113 is used as the signal amplitude. The difference between the impedance in the peripheral coil 112 and the impedance in the axial coil 113 is shown by the signal amplitude.

At the end of the defect shown in FIG. 8 (end of the region A31), the change in the depth of the defect (differentiation of the depth of the defect) is relatively large. As described above, in a portion where the change in the depth of the defect is relatively large, the difference between the impedance in the peripheral coil 112 and the impedance in the shaft coil 113 tends to be large, and the signal amplitude tends to be large.
On the other hand, in the defect itself shown in FIG. 8, the depth of the defect changes gently. That is, the change in defect depth is relatively small. As described above, in a portion where the change in the depth of the defect is relatively small, the difference between the impedance in the peripheral coil 112 and the impedance in the shaft coil 113 is small, and the signal amplitude is small. It becomes difficult to measure the depth of the defect with high accuracy, for example, the signal amplitude becomes small and it is easily affected by noise.

  As described above, in the case of a wide-area defect in which the depth of the defect changes gradually, it is difficult to measure the depth of the defect with high accuracy by the differential method. Therefore, in the eddy current flaw detector 1, flaw detection using both the peripheral coil 112 and the shaft coil 113 (differential method), and flaw detection using only one of the peripheral coil 112 or the shaft coil 113 (absolute method) Can be switched.

FIG. 9 is an explanatory diagram illustrating a second example of a connection state between the cross coil 111 and the current supply unit 130. As in FIG. 3, FIG. 9 shows one of the cross coils 111, the current supply unit 130, and a switch that switches the connection state between the cross coil 111 and the current supply unit 130 among the switches 120. Has been.
In the example of FIG. 9, the switch between the shaft coil 113 and the current supply unit 130 is in a connected state, whereas the switch between the peripheral coil 112 and the current supply unit 130 is in a disconnected state (OFF). It has become. In this state, the current supply unit 130 supplies current to the shaft coil 113 but does not supply current to the peripheral coil 112. Thereby, the eddy current flaw detector 1 performs flaw detection by the absolute method.

  As described above, in the differential method, the depth of the defect is obtained from the signal amplitude indicating the difference between the impedance in the peripheral coil 112 and the impedance in the axial coil 113. In contrast, in the absolute method, only one of the peripheral coil 112 and the shaft coil 113 is used to determine the depth of the defect from the signal amplitude indicating the impedance in the coil.

In the absolute method, since the signal amplitude corresponding to the distance (lift-off) between the coil and the flaw detection target can be obtained, the depth of the defect can be measured even when the depth of the defect changes gently.
Hereinafter, the mode in which the eddy current flaw detection apparatus 1 performs flaw detection by the differential method is referred to as “differential mode”.

Returning to FIG. 1, the eddy current flaw detector main body 200 switches between the differential mode and the absolute mode, and obtains the depth of the defect in the flaw detection target based on the signal amplitude in the eddy current flaw detection probe 100.
The eddy current flaw detector main body 200 is realized by an information processing device such as a personal computer (PC).

  Note that all or part of the functions of the eddy current flaw detector main body 200 may be performed by a person (user) in place of the eddy current flaw detector main body 200. For example, the user may switch between the differential mode and the absolute mode by switching the state of the switch 120 with reference to the signal amplitude in the eddy current flaw detection probe 100. The user may convert the signal amplitude in the eddy current flaw detection probe 100 into the depth of the defect.

The display unit 210 has a display screen such as a liquid crystal panel, and displays various types of information. In particular, the display unit 210 displays the depth of the defect in the flaw detection target obtained by the depth acquisition unit 294 based on the signal amplitude in the eddy current flaw detection probe 100.
The operation input unit 220 includes an input device such as a push button and receives a user operation. In particular, the operation input unit 220 receives a user operation instructing the start or end of flaw detection.

The storage unit 280 is realized by a storage device included in the eddy current flaw detector main body 200 and stores various types of information. In particular, the storage unit 280 stores a plurality of depth acquisition information in the absolute mode in advance. Furthermore, the storage unit 280 stores in advance depth acquisition information in the differential mode.
Each of the depth acquisition information stored in the storage unit 280 is information (calibration curve) indicating the relationship between the magnitude of the impedance detected by the detection unit 291 and the depth of the defect in the flaw detection target. This depth acquisition information is used by the depth acquisition unit 294 to obtain the depth of the defect in the inspection object based on the signal amplitude detected by the eddy current inspection probe 100.

  FIG. 10 is an explanatory diagram illustrating an example of depth acquisition information stored in the storage unit 280 in the absolute mode. The horizontal axis of the graph in FIG. The vertical axis represents the signal amplitude in the eddy current flaw detection probe 100. In the example of FIG. 10, the signal amplitude of the voltage across the coil is used as an example of the signal amplitude indicating the impedance of the coil.

  A line L11 indicates depth acquisition information for a wide area defect. A line L12 indicates depth acquisition information for local defects. In the absolute mode, the depth acquisition information selection unit 293 selects one of the plurality of depth acquisition information. Then, the depth acquisition unit 294 applies the signal amplitude in the eddy current flaw detection probe 100 to the depth acquisition information selected by the depth acquisition information selection unit 293 to determine the depth of the defect.

  Here, the present inventor has empirically learned that the ratio of the magnitude of the signal amplitude to the depth of the defect tends to be larger when the area of the defect is large than when the area of the defect is small. Yes. Therefore, the storage unit 280 is set with depth acquisition information for wide-area defects and depth acquisition information for local defects.

  The reason why the ratio of the amplitude of the signal to the depth of the defect tends to be larger when the area of the defect is larger than when the area of the defect is small is that not only the depth of the defect but also the area of the defect. It can be considered that the magnitude of the signal amplitude is affected. For example, in the case of a local defect, the eddy current detection target range is also applied to a healthy part (a part having no defect), so that the eddy current detection target range is substantially only a defective part. In comparison, it is conceivable that the signal amplitude becomes small.

  The storage unit 280 may store three or more pieces of depth acquisition information in advance. For example, the storage unit 280 previously stores depth acquisition information for defects in an intermediate area in addition to depth acquisition information for wide-area defects and depth acquisition information for local defects. You may make it memorize. In this case, the depth acquisition information selection unit 293 determines the area of the defect in three stages of wide area / intermediate / local, and selects depth acquisition information according to the determination result.

The control unit 290 controls each unit of the eddy current flaw detector 1 and executes various functions. The control unit 290 is realized by, for example, a CPU (Central Processing Unit) included in the eddy current flaw detector main body 200 reading and executing a program from the storage unit 280.
The detection unit 291 detects the coil impedance in each cross coil. Specifically, in the differential mode, the detection unit 291 detects a signal amplitude indicating a difference between the impedance in the peripheral coil 112 and the impedance in the shaft coil 113. In the absolute mode, the detection unit 291 detects a signal amplitude indicating the impedance of either the circumferential coil 112 or the shaft coil 113 (which receives current supply).
As the signal amplitude indicating the impedance in the coil detected by the detection unit 291, for example, the signal amplitude of the voltage across the coil can be used.

The flaw detection method switching unit 292 performs switching from the differential mode to the absolute mode. More specifically, the flaw detection method switching unit 292 changes the connection relationship of the switch 120 when the detection result of the detection unit 291 in the differential mode satisfies a predetermined condition (hereinafter referred to as “flaw detection method switching condition”). Switch to absolute mode.
Here, the differential mode corresponds to an example of a state in which the current supply unit 130 supplies current to a plurality of coils per cross coil 111. The absolute mode corresponds to an example of a state in which the current supply unit 130 supplies current to one coil for each cross coil.

  Further, the flaw detection method switching unit 292 can use, for example, a condition as to whether or not a defect is detected in any of the cross coils 111 as the flaw detection method switching condition. That is, when a defect is detected in the flaw detection range in the differential mode, the flaw detection method switching unit 292 switches from the differential mode to the absolute mode by switching the state of the switch 120. Then, the eddy current flaw detection apparatus 1 performs flaw detection in the pipe 900 again in the absolute mode.

The depth acquisition information selection unit 293 selects one of the plurality of depth acquisition information stored in the storage unit 280 according to the detection result of the detection unit 291 in the absolute mode.
More specifically, the depth acquisition information selection unit 293 selects the depth acquisition information for a wide-area defect when the detection result suggests the existence of a wide-area defect, otherwise Selects depth acquisition information for local defects.

  For example, when a defect is detected in n (n is a positive integer greater than or equal to 2) cross coils 111, the depth acquisition information selection unit 293 selects depth acquisition information for a wide area defect. . On the other hand, if the number of cross coils 111 in which defects are detected is less than n, the depth acquisition information selection unit 293 selects local defect depth acquisition information.

Alternatively, the conditions used by the depth acquisition information selection unit 293 may depend on the defect detection position. For example, when a defect is detected in n (n is a positive integer of 2 or more) consecutive or adjacent cross coils 111 or more, the depth acquisition information selection unit 293 acquires the depth for a wide area defect. Select information for use. Further, for example, when n = 3, when a defect is detected in any one of the cross coils 111 and the adjacent cross coils 111, the depth acquisition information selection unit 293 displays depth acquisition information for a wide area defect. select. In other cases, the depth acquisition information selection unit 293 selects depth acquisition information for local defects.
As described above, the depth acquisition information selection unit 293 may use a condition that depends on the detection position of the defect to erroneously determine that the defect is a wide-area defect when there are a plurality of local defects. Can be reduced. This increases the possibility that appropriate depth acquisition information can be selected. In this respect, the accuracy of measuring the depth of the defect can be increased.

  Furthermore, the conditions used by the information acquisition unit for depth acquisition 293 may depend on the magnitude relationship between signal amplitudes in successive defects. For example, the depth acquisition information selection unit 293 detects a defect in one of the cross coils 111 and the adjacent cross coils 111 and the signal amplitude in the adjacent cross coils 111 is the signal amplitude in the central cross coil 111. If it is 50 percent (%) or more, the depth acquisition information for a wide area defect is selected. In other cases, the depth acquisition information selection unit 293 selects depth acquisition information for local defects.

  The depth acquisition unit 294 uses the depth acquisition information selected by the depth acquisition information selection unit 293 to determine the depth of the defect in the inspection target from the detection result of the detection unit 291 (signal amplitude in the eddy current inspection probe 100). I ask for it. More specifically, the depth acquisition unit 294 uses the depth acquisition information selected by the depth acquisition information selection unit 293 to convert the signal amplitude in the eddy current flaw detection probe 100 into a defect depth.

Next, the operation of the eddy current flaw detector 1 will be described with reference to FIG.
FIG. 11 is a flowchart showing a processing procedure in which the eddy current flaw detector 1 performs eddy current flaw detection. In the process shown in FIG. 10, the eddy current flaw detector 1 performs flaw detection in the differential mode (step S101).
More specifically, the flaw detection method switching unit 292 connects both the switch between the peripheral coil 112 and the current supply unit 130 and the switch between the shaft coil 113 and the current supply unit 130 in the switch 120. State. As a result, the flaw detection method switching unit 292 sets the mode of the eddy current flaw detection apparatus 1 to the differential mode.
Then, the eddy current flaw detection probe 100 moves in the flaw detection range in the pipe 900, and the eddy current flaw detection apparatus 1 performs the process of FIG. 12 for each sampling.

FIG. 12 is a flowchart showing a procedure of processing performed by the eddy current flaw detector 1 for each sampling in the differential mode. In the process of FIG. 9, the detection unit 291 detects the signal amplitude in the eddy current flaw detection probe 100 (step S201).
Next, the depth acquisition unit 294 acquires the depth of the defect based on the signal amplitude detected by the detection unit 291 in step S101 (step S202).
More specifically, in the differential mode, the depth acquisition information selection unit 293 selects the depth acquisition information for the differential mode. Then, the depth acquisition unit 294 converts the signal amplitude detected by the detection unit 291 into a defect depth using the differential mode depth acquisition information selected by the depth acquisition information selection unit 293.
Then, the display unit 210 displays the defect depth acquired by the depth acquisition unit 294 in step S202 (step S203).
Thereafter, the process of FIG.

The eddy current flaw detection probe 100 moves through the entire flaw detection range in the pipe 900, and the eddy current flaw detection device 1 performs the processing of FIG. 12 for each sampling, so that the eddy current flaw detection device 1 performs differential mode for each position in the flaw detection range. Perform flaw detection at
In order to detect the entire flaw detection range, the eddy current flaw detection probe 100 may move in the pipe 900 in a self-propelled manner, or the eddy current flaw detection probe 100 may be moved manually.

Note that the depth acquisition unit 294 may acquire the defect depth in step S202 in a plurality of times. For example, the detection unit 291 may detect the signal amplitude in step S201 at each sampling timing, and the storage unit 280 may store the detection result. Then, after the detection of the signal amplitude is completed for the entire flaw detection range, the depth acquisition unit 294 may acquire the depth of the defect in step S202.
When the user executes the function of the depth acquisition unit 294, the display unit 210 displays the signal amplitude detected by the detection unit 291. Then, the user converts the signal amplitude displayed on the display unit 210 into a defect depth using a predetermined calibration curve.

Returning to FIG. 11, after step S101, the flaw detection method switching unit 292 satisfies the flaw detection method switching condition for the depth of the defect acquired by the depth acquisition unit 294 in step S101 (step S202 in FIG. 12). It is determined whether or not there is (step S102).
For example, as described above, when a defect is detected within the flaw detection range, the flaw detection method switching unit 292 determines that the flaw detection method switching condition is satisfied. Here, in the determination of the presence / absence of a defect, a determination condition of whether or not the depth of the defect is equal to or greater than a predetermined threshold can be used. For example, if the depth of the defect is greater than or equal to a predetermined threshold at any position in the flaw detection range, the flaw detection method switching unit 292 determines that the flaw detection method switching condition is satisfied.
When the user switches the mode, the presence / absence of a user operation instructing the flaw detection in the absolute mode is used as the flaw detection method switching condition in step S102.

If it is determined in step S102 that the flaw detection method switching condition is not satisfied (step S102: NO), the processing in FIG. 11 is terminated.
On the other hand, when it is determined in step S102 that the flaw detection method switching condition is satisfied (step S102: YES), the eddy current flaw detector 1 performs flaw detection in the absolute mode (step S103).

More specifically, the flaw detection method switching unit 292 is one of a switch between the peripheral coil 112 and the current supply unit 130 and a switch between the shaft coil 113 and the current supply unit 130 in the switch 120. Is connected and the other is disconnected. As a result, the flaw detection method switching unit 292 switches the mode of the eddy current flaw detection apparatus 1 from the differential mode to the absolute mode.
Then, the eddy current flaw detection probe 100 moves in the flaw detection range in the pipe 900, and the eddy current flaw detection apparatus 1 performs the process of FIG. 13 for each sampling.

FIG. 13 is a flowchart showing a procedure of processing performed by the eddy current flaw detector 1 for each sampling in the absolute mode. In the process of FIG. 9, the detection unit 291 detects the signal amplitude in the eddy current flaw detection probe 100 (step S301).
Next, the depth acquisition information selection unit 293 selects a condition for selecting wide area defect acquisition information (hereinafter, “wide area condition”) for the signal amplitude detected by the detection unit 291 in step S111. Is determined) (step S302).

  As described above, as the wide area condition, for example, a condition of whether or not a defect is detected in n or more cross coils 111 is used. Or you may make it use the condition of whether the defect was detected in the n or more continuous cross coils 111 as a wide area condition. Alternatively, as a wide-area condition, whether or not a defect is detected in one of the cross coils 111 and the adjacent cross coils 111 and the signal amplitude in the adjacent cross coils 111 is 50% or more of the signal amplitude in the central cross coil 111. The condition may be used.

In step S302, when it is determined that the wide area condition is satisfied (step S302: YES), the depth acquisition information selection unit 293 includes the wide area information among the depth acquisition information stored in the storage unit 280. The depth acquisition information for the correct defect is selected (step S311).
Then, the depth acquisition unit 294 acquires the depth of the defect based on the signal amplitude detected by the detection unit 291 in step S301 (step S331). More specifically, the depth acquisition unit 294 uses the wide-area depth acquisition information selected by the depth acquisition information selection unit 293 to determine the signal amplitude detected by the detection unit 291 as a defect. Convert to depth.
And the display part 210 displays the depth of the defect which the depth acquisition part 294 acquired by step S331 (step S332).
Thereafter, the process of FIG. 13 is terminated.

On the other hand, when it is determined in step S302 that the wide area condition is not satisfied (step S302: NO), the depth acquisition information selection unit 293 includes the depth acquisition information stored in the storage unit 280. Local depth acquisition information is selected (step S321).
Thereafter, the process proceeds to operation S331.

The eddy current flaw detection probe 100 moves over the entire flaw detection range in the pipe 900, and the eddy current flaw detection device 1 performs the processing of FIG. 13 for each sampling, so that the eddy current flaw detection device 1 performs an absolute mode for each position in the flaw detection range. Perform flaw detection at
As in the case of the differential mode, the eddy current flaw detection probe 100 may be moved in the pipe 900 in a self-propelled manner, or the eddy current flaw detection probe 100 may be moved manually.

  The depth acquisition unit 294 may acquire the defect depth in step S331 in a plurality of times. For example, the detection unit 291 may detect the signal amplitude in step S301 at each sampling timing, and the storage unit 280 may store the detection result. Then, after the detection of the signal amplitude is completed for the entire flaw detection range, the depth acquisition information selection unit 293 performs the determination in step S302 on each signal amplitude detection result for each sampling timing to obtain the depth acquisition information. May be selected. Then, the depth acquisition unit 294 may acquire the defect depth in step S311 using the depth acquisition information selected by the depth acquisition information selection unit 293.

  When the user executes the function of the depth acquisition unit 294, the display unit 210 displays the signal amplitude detected by the detection unit 291. Then, based on the signal amplitude displayed on the display unit 210, the user selects either the depth acquisition information for a wide area defect or the depth acquisition information for a local defect, and selects The signal amplitude is converted into the depth of the defect using the obtained depth acquisition information.

When flaw detection is performed using the peripheral coil 112, it is easy to detect a defect that is long in the axial direction of the pipe 900 (direction parallel to the axis of the pipe 900). On the other hand, when flaw detection is performed using the shaft coil 113, it is easy to detect a defect that is long in the circumferential direction of the pipe 900 (direction perpendicular to the axis of the pipe 900).
In the piping, generally, axial defects are likely to occur. By making the eddy current flaw detector 1 use the peripheral coil 112 in the absolute mode, it becomes easy to detect such an axial defect.
Returning to FIG. 11, after step S103, the process of FIG. 11 is terminated.

As described above, a plurality of cross coils are arranged in the probe main body 110, and each cross coil is configured by combining the peripheral coil 112 and the axial coil 113 wound around different axes intersecting each other. Yes.
The switch 120 is connected to the current supply unit 130 and the peripheral coil 112 so that current is supplied to at least one of the peripheral coil 112 and the axial coil 113 constituting each cross coil 111, The connection between the supply unit 130 and the shaft coil 113 is switched.

Thus, the user can perform both differential eddy current testing and absolute eddy current testing using a single eddy current testing probe 100. In particular, for a defect such as a local defect that has a relatively rapid change in the depth of the defect, the influence of noise such as a temperature change can be reduced by performing eddy current flaw detection using a differential method. Further, for a defect having a wide range and having a relatively slow change in the depth of the defect, the depth of the defect can be obtained by performing eddy current flaw detection using an absolute method.
As described above, when the eddy current flaw detection probe 100 switches between the differential method and the absolute method, a local defect and a wide-area defect in which the depth of the defect gently changes are mixed in the flaw detection target. However, the depth of both defects can be obtained more accurately.

In addition, the flaw detection method switching unit 292 determines the connection relationship of the switch 120 when the detection result of the detection unit 291 in the differential mode satisfies the flaw detection method switching condition. It switches so that an electric current may be supplied to either one of the axial coils 113.
As a result, the eddy current flaw detector 1 automatically switches to the absolute mode according to the detection result of the detection unit 291 in the differential mode, such as switching to the absolute mode when a defect is detected in the differential mode. Switching can be performed.

The storage unit 280 stores a plurality of pieces of depth acquisition information indicating the relationship between the magnitude of the impedance (the magnitude of the signal amplitude) detected by the detection unit 291 and the depth of the defect in the flaw detection target. Then, the depth acquisition information selection unit 293 selects one of the depth acquisition information stored in the storage unit 280 according to the detection result of the detection unit 291 in the absolute mode. Then, the depth acquisition unit 294 obtains the depth of the defect in the flaw detection target from the detection result of the detection unit 291 using the depth acquisition information selected by the depth acquisition information selection unit 293.
Thereby, the depth acquisition unit 294 can obtain the depth of the defect using the depth acquisition information corresponding to the size of the defect. In this respect, the eddy current flaw detector 1 can obtain the depths of both defects more accurately even when local defects and wide-area defects are mixed in the flaw detection target.

A program for realizing all or part of the functions of the eddy current flaw detector main body 200 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. The processing of each unit may be performed as necessary. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Eddy current flaw detection apparatus 100 Eddy current flaw detection probe 110 Probe main body 111 Cross coil 112 Circumferential coil 113 Axis coil 120 Switch 130 Current supply part 200 Eddy current flaw detection apparatus main body 210 Display part 220 Operation input part 280 Storage part 290 Control part 291 Detection part 292 flaw detection method switching unit 293 depth acquisition information selection unit 294 depth acquisition unit

Claims (6)

A probe body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other,
A current supply unit capable of supplying a current to each of the plurality of coils constituting each cross coil;
By switching the connection between the coil and the front SL current supply section, and the differential mode for supplying a current to each of the plurality of coils constituting each cross coil, the one of the plurality of coils constituting each cross A switch for switching between the absolute mode for flowing current only to the coil ,
When a defect is detected in any of the plurality of cross coils in the differential mode, a flaw detection method switching unit that switches to the absolute mode by switching the connection relationship of the switch;
An eddy current flaw detection probe comprising: A probe body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other,
A current supply unit capable of supplying a current to each of the plurality of coils constituting each cross coil;
Before SL by switching the connection between the coil and the current supply unit, each of the differential mode for supplying a current to each of the plurality of coils constituting the cross coil, one coil per one cross coils for each of the cross coil A switch for switching between the absolute mode for flowing current only to
A detection unit for detecting the impedance of the coil in each cross coil;
In any of the plurality of cross coils in the differential mode, when a defect is detected based on the impedance, a flaw detection method switching unit that switches to the absolute mode by switching the connection relationship of the switch;
An eddy current flaw detector comprising: A storage unit for storing a plurality of depth acquisition information indicating a relationship between the magnitude of the impedance detected by the detection unit and the depth of a defect in a flaw detection target;
In the absolute mode, when a defect is detected in a predetermined number of adjacent cross coils among the plurality of cross coils, the depth acquisition information for a wide area defect is selected. A depth acquisition information selection section for selecting depth acquisition information for various defects ;
Using the depth acquisition information selected by the depth acquisition information selection unit, a depth acquisition unit for obtaining the depth of the defect in the flaw detection target from the detection result of the detection unit;
The eddy current flaw detector according to claim 2 comprising:   A storage unit for storing a plurality of depth acquisition information indicating a relationship between the magnitude of the impedance detected by the detection unit and the depth of a defect in a flaw detection target;
  In the absolute mode, a defect is detected in any one of the plurality of cross coils and the adjacent cross coils, and the signal amplitude in the adjacent cross coils is 50% or more of the signal amplitude in the central cross coil. A depth acquisition information selection unit that selects depth acquisition information for a wide-area defect, and otherwise selects depth acquisition information for a local defect;
  Using the depth acquisition information selected by the depth acquisition information selection unit, a depth acquisition unit for obtaining the depth of the defect in the flaw detection target from the detection result of the detection unit;
  The eddy current flaw detector according to claim 2 comprising: A probe body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other,
A current supply unit capable of supplying a current to each of the plurality of coils constituting each cross coil;
By switching the connection between the coil and the front SL current supply section, and the differential mode for supplying a current to each of the plurality of coils constituting each cross coil, the one of the plurality of coils constituting each cross A switch for switching between the absolute mode for flowing current only to the coil ,
A detection unit for detecting the impedance of the coil in each cross coil;
An eddy current flaw detection method using an eddy current flaw detection apparatus comprising:
In any of the plurality of cross coils in the differential mode, if a defect is detected on the basis of the impedance, vortex having a flaw detection method switching step of switching to the absolute mode by switch the connection relationship of the switch Current flaw detection method. A probe body in which a plurality of cross coils, each of which is a combination of a plurality of coils wound around different axes intersecting each other,
A current supply unit capable of supplying a current to each of the plurality of coils constituting each cross coil;
By switching the connection between the coil and the front SL current supply section, and the differential mode for supplying a current to each of the plurality of coils constituting each cross coil, the one of the plurality of coils constituting each cross A switch for switching between the absolute mode for flowing current only to the coil ,
A detection unit for detecting the impedance of the coil in each cross coil;
An eddy current flaw detection method using an eddy current flaw detection apparatus comprising:
In the absolute mode, when a defect is detected in a predetermined number of adjacent cross coils among the plurality of cross coils, the relationship between the magnitude of the impedance detected by the detection unit and the depth of the defect in the flaw detection target is determined. shown, wide-area select depth obtaining information for defect, other local depth acquired information to select the depth obtaining information for defect case of a plurality of depth obtaining information A selection step;
Using the depth acquisition information selected in the depth acquisition information selection step, a depth acquisition step for obtaining the depth of the defect in the flaw detection target from the detection result of the detection unit;
An eddy current flaw detection method.

Images