JP2020034509A - Inspection device for magnetic material - Google Patents

Abstract

To provide an inspection device for magnetic material capable of inspecting the state of magnetic material (whether there is any scratch etc.) with a simple configuration.SOLUTION: An inspection device for magnetic material 100 (200) includes: a magnetic field application unit 1 that applies the magnetic field in advance and adjusts the magnetization direction of steel wire rope W; and a detection unit 2 that acquires a detection signal on the basis of changes of the magnetic field of the steel wire rope W after the magnetic field is applied by magnetic field application unit 1. The detection unit 2 is configured to acquire the difference (differential signal H) between the magnitudes of the respective detection signals generated in the two detection coils 22a and 22b included in the differential coil 22.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a magnetic body inspection apparatus, and more particularly, to a magnetic body inspection apparatus including a detection unit that acquires a detection signal based on a change in a magnetic field of a magnetic body.

  2. Description of the Related Art Conventionally, there has been known a magnetic body inspection apparatus including a detection unit that acquires a detection signal based on a magnetic field of a magnetic body (for example, see Patent Document 1).

  Patent Literature 1 includes a magnetic detection unit that moves along the longitudinal direction of a reinforcing bar (magnetic material) in concrete to which a magnetic field is applied in advance and detects a magnetic field of the reinforcing bar. ), A non-destructive inspection device (magnetic device inspection device) is disclosed. In the inspection apparatus for a magnetic body described in Patent Document 1, a permanent magnet in which an N pole and an S pole are arranged along the longitudinal direction of the reinforcing bar is used to magnetize the reinforcing bar in advance. In the magnetic body inspection apparatus disclosed in Patent Document 1, as a magnetic detection unit, an MI sensor that is a magnetic sensor using a magnetic impedance (MI: MAGNETO IMPEDANCE) effect of an amorphous magnetic wire, A fluxgate magnetic sensor, which is a magnetic sensor using the magnetization saturation of a magnetic permeability material, is used.

JP 2006-177747 A

  However, although the MI sensor and the fluxgate magnetic sensor can detect an external magnetic field with relatively high accuracy, the elements and electronic circuits constituting the sensor are relatively complicated. For this reason, in the magnetic body inspection device described in Patent Document 1, since the MI sensor and the fluxgate magnetic sensor are used as the magnetic detection unit, the device configuration of the inspection device is relatively complicated. A point is conceivable.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. One object of the present invention is to provide a magnetic material capable of inspecting the state of a magnetic body (whether or not there is a flaw or the like) with a simple configuration. It is to provide a body examination device.

  In order to achieve the above object, a magnetic body inspection apparatus according to one aspect of the present invention includes a magnetic field application unit that applies a magnetic field to a magnetic body to be inspected in advance to adjust the direction of magnetization of the magnetic body, And a detection unit that obtains a detection signal based on a change in the magnetic field of the magnetic body after the magnetic field is applied by the application unit. The detection unit is arranged along the longitudinal direction, and the detection unit includes a differential coil, and is configured to acquire a difference between magnitudes of respective detection signals generated by two coil portions included in the differential coil. ing.

  In the magnetic body inspection apparatus according to one aspect of the present invention, as described above, the detection unit acquires a difference between the magnitudes of the respective detection signals generated in the two coil portions included in the differential coil. As a result, different voltages (detection signals) are generated in the two coil portions based on the change in the magnetic field of the magnetic body. Therefore, by acquiring the difference between the magnitudes of the two detection signals, the local magnetic field of the magnetic body is obtained. Can be easily detected. As a result, the state of the magnetic material (presence or absence of a flaw or the like) that causes a local magnetic field change can be determined by a simple configuration using the two coil portions having a relatively simple structure included in the differential coil. Can be inspected. In addition, since the direction of magnetization of the magnetic body is adjusted in advance by the magnetic field applying unit, the state of the magnetic body (whether there is a flaw or the like) can be inspected while noise appearing in the detection signal is reduced. As a result, the presence / absence of a flaw or the like of the magnetic body can be easily determined as compared with the case where the direction of magnetization of the magnetic body is not adjusted. Can be inspected.

  In the magnetic body inspection apparatus according to the one aspect, preferably, the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body is such that the detection unit is relatively moved in the longitudinal direction of the magnetic body. Is set based on the amount of movement of the differential coil during the measurement cycle of the differential coil when detecting a change in the magnetic field of the magnetic material. Here, since the measurement cycle of the differential coil generally has a small value of, for example, about several ms, the amount of movement of the differential coil during the measurement cycle of the differential coil is also a small value. Become. Therefore, with the above configuration, the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body is reduced, so that a local change in the state of the magnetic body (whether there is a flaw or the like) can be ensured. Can be detected. Note that if the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body is smaller than the amount of movement of the differential coil during the measurement cycle of the differential coil, the detection unit is set to be magnetic. When a change in the magnetic field of the magnetic body is detected by relatively moving the magnetic body in the longitudinal direction, an undetected portion occurs in the magnetic body. Therefore, the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body is different from that in the case where the change in the magnetic field of the magnetic body is detected by relatively moving the detection unit in the longitudinal direction of the magnetic body. It is preferable to set a value that is substantially equal to or more than the moving amount of the differential coil during the measurement cycle of the moving coil and is relatively small.

  In this case, preferably, the difference between the magnitude of the detection signal obtained by the differential coil at the first position in the longitudinal direction of the magnetic body and the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body To calculate a difference value obtained by subtracting the magnitude of the detection signal acquired by the differential coil at the second position separated by a predetermined distance from the first position in the longitudinal direction of the magnetic body based on The apparatus further includes a signal processing unit that performs signal processing. According to this configuration, when the measured waveform is shown with the longitudinal position of the magnetic body as the horizontal axis and the difference (signal strength) of the magnitude of the detection signal acquired by the differential coil as the vertical axis, In the above, a portion where the signal intensity greatly changes with respect to a change in the position of the magnetic body in the longitudinal direction can be extracted as a large difference value. This makes it possible to easily extract a portion where the negatively convex portion and the positively convex portion of the signal intensity appearing in the measured waveform when the magnetic material has a flaw or the like are adjacent to each other. As a result, for example, even when the measurement waveform is not adjusted (including noise) due to the magnetization direction of the magnetic material being not sufficiently adjusted, the local state of the state of the magnetic material (whether or not there is a flaw or the like) is obtained. Such a change can be easily detected.

  In the configuration including the signal processing unit, preferably, the signal processing unit is configured to perform signal processing for setting a negative value of the difference value to zero. With this configuration, it is possible to extract, as the difference value, only a portion of the measurement waveform where the signal intensity increases with respect to a change in the position of the magnetic body in the longitudinal direction. Thus, for example, when taking a difference from a side having a convex portion on the positive side of the signal intensity to a side having a convex portion on the negative side in the measured waveform, for example, the difference between the convex portion on the negative side of the signal intensity and the positive side is obtained. Of the portions adjacent to the convex portion, it is possible to extract a portion where the signal intensity changes significantly from the top of the negatively convex portion to the top of the positively convex portion of the signal intensity. As a result, even when the measurement waveform is not aligned due to the magnetization direction of the magnetic body not being sufficiently adjusted, a local change in the state of the magnetic body (whether there is a flaw or the like) can be more easily detected. be able to.

  In the configuration including the signal processing unit, preferably, the signal processing unit is configured to perform the difference signal processing on a difference between the magnitudes of the detection signals on which the noise reduction processing has been performed. With this configuration, the difference signal processing can be performed after the influence of the disturbance of the measurement waveform due to the noise (noise) of the electronic circuit is reduced by the noise reduction processing. As a result, even if the noise of the electronic circuit is detected due to a decrease in the center-to-center distance between the two coil portions of the differential coil in the longitudinal direction of the magnetic body, the effect of the noise of the electronic circuit is reduced. Thus, in the measurement waveform, a portion where the signal intensity greatly changes with respect to a change in the position of the magnetic body in the longitudinal direction can be extracted as the difference value.

  In the magnetic body inspection apparatus according to the one aspect, preferably, the magnetic body is made of a long material, and the two coil portions included in the differential coil are arranged side by side along the longitudinal direction of the long material. Are located. According to this configuration, since the two coil portions are arranged so as to be aligned with each other along the longitudinal direction of the long material, the local state of the state of the long material (magnetic material) (presence or absence of a flaw or the like) is obtained. The change can be detected along the longitudinal direction of the long material (magnetic material). As a result, it is possible to inspect the state (whether or not there is a flaw) of the long material (magnetic material) along the longitudinal direction of the long material, so that the detection unit is relatively moved along the longitudinal direction of the long material. By doing so, it is possible to easily inspect the entire long material (magnetic material) such as a wire rope.

  In the magnetic body inspection apparatus according to the above aspect, the magnetic field applying unit is preferably provided at a position separated from the detection unit in the longitudinal direction of the magnetic body so that the output magnetic field does not affect the detection by the detection unit. Have been. According to this structure, it is possible to suppress noise caused by the magnetic field output by the magnetic field application unit from being detected by the detection unit.

  In the magnetic body inspection apparatus according to the one aspect, preferably, the magnetic field applying unit is a first magnetic field applying unit disposed on one side in a longitudinal direction of the magnetic body with respect to the detecting unit; And a second magnetic field applying unit disposed on the other side of the second magnetic field. According to this structure, the first magnetic field applying unit and the second magnetic field applying unit are disposed on one side and the other side in the longitudinal direction of the magnetic body, respectively. In either case, the magnetization direction can be adjusted by applying a magnetic field to the magnetic body in advance.

  In the magnetic body inspection apparatus according to the above aspect, preferably, the magnetic field applying unit is disposed on one side and the other side of the magnetic body in the lateral direction of the magnetic body so as to face the magnetic body. Have been. According to this structure, the magnetic field applying portions are arranged on one side and the other side in the short direction orthogonal to the longitudinal direction of the magnetic body so as to face each other with the magnetic body interposed therebetween. Since the magnetic field applied to the magnetic body can be easily increased as compared with the case where the magnetic field applying section is arranged only on one side of the magnetic field, the direction of magnetization of the magnetic body can be adjusted efficiently.

  In this case, preferably, a magnetic field applying unit arranged on one side in the short direction of the magnetic body and a magnetic field applying unit arranged on the other side in the short direction of the magnetic body so as to face each other with the magnetic body interposed therebetween. Is arranged so that the N pole and the S pole of the magnetic field applying unit are on the same side in the longitudinal direction of the magnetic body. According to this structure, the same poles of the magnetic field applying portions arranged on one side and the other side in the short direction of the magnetic body so as to face each other with the magnetic body interposed therebetween are arranged on the same side in the longitudinal direction of the magnetic body. Therefore, the direction of the magnetic field applied to the magnetic body by the magnetic field applying unit arranged on one side in the short direction of the magnetic body and the magnetic field applying unit arranged on the other side in the short direction of the magnetic body Thereby, the direction of the magnetic field applied to the magnetic body can be made uniform. As a result, the magnetic field applied to the magnetic body can be more easily increased, so that the direction of magnetization of the magnetic body can be more efficiently arranged.

  In the magnetic body inspection apparatus according to the one aspect, preferably, the detection unit further includes an excitation coil for exciting a state of magnetization of the magnetic body, and the differential coil is generated by an excitation current flowing through the excitation coil. It is configured to acquire a detection signal based on a change in the magnetic field of the magnetic body whose magnetization state is excited by the magnetic field. With this configuration, the magnetization state of the magnetic body is excited by the excitation coil, and the magnetic field of the magnetic body can be changed over time. Therefore, the magnetic field of the magnetic body can be changed without relatively moving the magnetic body and the detection unit. Can be detected.

  According to the present invention, as described above, the state of the magnetic body (whether or not there is a flaw) can be inspected with a simple configuration.

FIG. 1 is a diagram for explaining an entire configuration of a mobile X-ray fluoroscopic apparatus including a magnetic body inspection apparatus according to first and second embodiments of the present invention. FIG. 1 is a block diagram showing an overall configuration of a magnetic body inspection apparatus according to first and second embodiments of the present invention. FIG. 5 is a diagram for explaining a magnetic field application unit according to the first and second embodiments of the present invention. FIG. 3 is a diagram for explaining a detection unit according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining excitation of magnetization of an excitation coil according to the first and second embodiments of the present invention. It is a figure showing a case where a steel wire rope has a crack etc. FIG. 2 is a block diagram illustrating an electronic circuit unit according to first and second embodiments of the present invention. It is a figure for explaining the direction of magnetization of the steel wire rope by a comparative example. 5 is a measurement waveform of a differential signal of a magnetic body according to the first embodiment of the present invention and a comparative example. It is a figure for explaining a detecting part by a 2nd embodiment of the present invention. FIG. 7 is a diagram for explaining signal processing of a differential signal according to a second embodiment of the present invention. It is a figure for explaining the magnetic field application part by the modification of a 1st and 2nd embodiment of the present invention. It is a figure for explaining a detecting part by a modification of a 1st and 2nd embodiment of the present invention. It is another figure for demonstrating the detection part by the modification of 1st and 2nd embodiment of this invention. FIG. 11 is yet another diagram illustrating a detection unit according to a modification of the first and second embodiments of the present invention. FIG. 9 is a diagram for explaining an X-ray imaging apparatus according to a modification of the first and second embodiments of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of the inspection apparatus 100 according to the first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, an example will be described in which the inspection device 100 is used to inspect a steel wire rope W built in a mobile X-ray imaging device (rounding car) 900. The inspection device 100 is an example of the “magnetic device inspection device” in the claims.

(Configuration of mobile X-ray imaging apparatus)
As shown in FIG. 1, the mobile X-ray imaging apparatus 900 includes an X-ray irradiator E1 configured to be movable in a vertical direction (X direction) with respect to a column P, and a portable X-ray detector E2. And is configured to be movable by wheels. The X-ray irradiator E1 irradiates the subject with X-rays. The X-ray detector E2 detects X-rays transmitted through the subject and receives an X-ray image. Further, the X-ray irradiator E1 and the X-ray detector E2 are each composed of, for example, an X tube and an FPD (flat panel detector). In the column P, a steel wire rope W for pulling and supporting the X-ray irradiation unit E1 and an inspection device 100 configured to be movable in the vertical direction (X direction) in which the steel wire rope W extends are built in. Have been. The steel wire rope W is an example of the “magnetic material” and the “long material” in the claims.

  The steel wire rope W is a magnetic material formed by knitting (for example, strand knitting) a magnetic element material having magnetism and made of a long material extending in the X direction. Although not shown, the steel wire rope W passes through a mechanism such as a pulley when moving the X-ray irradiator E1, and is subjected to stress due to the pulley or the like. For this reason, in order to prevent the steel wire rope W from being cut due to deterioration and from dropping the X-ray irradiator E1, the state of the steel wire rope W (whether there is a scratch or the like) is regularly monitored and the deteriorated steel wire W is monitored. It is necessary to replace the rope W at an early stage.

(Configuration of inspection device)
As shown in FIG. 2, the inspection device 100 includes a magnetic field application unit 1, a detection unit 2, and an electronic circuit unit 3. The magnetic field applying unit 1, the detecting unit 2, and the electronic circuit unit 3 are fixed to the frame F as the inspection unit U, and are moved in the longitudinal direction (X direction) of the steel wire rope W by a driving unit (not shown). It is configured to be possible. Note that directions perpendicular to each other in a plane perpendicular to the longitudinal direction (X direction) of the steel wire rope W are referred to as Y direction and Z direction.

  As shown in FIG. 3, in the first embodiment, the magnetic field applying unit 1 is configured to apply a magnetic field in advance to the steel wire rope W to be inspected and to adjust the direction of magnetization of the steel wire rope W. I have. Specifically, the magnetic field applying unit 1 is configured by a permanent magnet, and the N pole and the S pole of the magnetic field applying unit 1 are arranged so as to be along the longitudinal direction (X direction) of the steel wire rope W. That is, the magnetic field applying unit 1 is configured to apply a magnetic field to the steel wire rope W in a substantially X direction. In the drawings, the N pole and the S pole of the magnetic field applying unit 1 are shown with and without oblique lines, respectively.

  Further, in the first embodiment, the magnetic field application unit 1 is located at a position separated from the detection unit 2 in the longitudinal direction (X direction) of the steel wire rope W so that the output magnetic field does not affect the detection by the detection unit 2. It is provided in. Specifically, if the distance between the magnetic field application unit 1 and the detection unit 2 is too short, the magnetic field by the magnetic field application unit 1 may be detected by the detection unit 2. For this reason, the magnetic field applying unit 1 is provided at a position that is separated to such an extent that the influence on the detecting unit 2 does not matter.

  Further, in the first embodiment, the magnetic field applying unit 1 includes a magnetic field applying unit 11 disposed on one side (X1 side) in the longitudinal direction (X direction) of the steel wire rope W, and a longitudinal direction (X1) of the steel wire rope W. And a magnetic field applying unit 12 disposed on the other side (X2 side) in the (X direction). Therefore, when the inspection unit U is moved in the X1 direction to relatively move the steel wire rope W with the magnetic field application unit 1 and the detection unit 2 provided in the inspection unit U, the magnetic field application unit 11 causes the detection unit 2 to move. A magnetic field is applied to the portion to be inspected in advance, and the direction of magnetization is adjusted. In addition, when the inspection unit U is moved in the X2 direction to relatively move the magnetic field application unit 1 and the detection unit 2 provided in the inspection unit U and the steel wire rope W, the magnetic field application unit 12 detects the steel wire rope W. A magnetic field is applied to the portion to be inspected in advance, and the direction of magnetization is adjusted. The magnetic field applying unit 11 and the magnetic field applying unit 12 are examples of the “first magnetic field applying unit” and the “second magnetic field applying unit” in the claims, respectively.

  The magnetic field applying unit 11 has N and S poles arranged on the X1 side and the X2 side, respectively, and is configured to apply a magnetic field in a substantially X2 direction to the steel wire rope W. The magnetic field applying unit 12 has N and S poles arranged on the X2 side and the X1 side, respectively, and is configured to apply a magnetic field substantially in the X1 direction to the steel wire rope W. Therefore, before and after the inspection, the direction in which the steel wire rope W is magnetized by the magnetic field application unit 1 is reversed, so that the magnetization hardly remains on the steel wire rope W after the inspection.

  Further, in the first embodiment, the magnetic field applying unit 1 is positioned on one side of the steel wire rope W in the short direction (Y direction) with respect to the steel wire rope W so as to face the steel wire rope W therebetween. Y1 side) and the other side (Y2 side). Specifically, the magnetic field application unit 11 includes a magnetic field application unit 11a disposed on one side (Y1 side) in the short direction (Y direction) of the steel wire rope W, and a short direction (Y And a magnetic field applying unit 11b disposed on the other side (Y2 side) of the second direction (Y direction). The magnetic field applying unit 11a and the magnetic field applying unit 11b are arranged to face each other with the steel wire rope W interposed therebetween. The magnetic field applying unit 12 includes a magnetic field applying unit 12a disposed on one side (Y1 side) in the short direction (Y direction) of the steel wire rope W and a magnetic field applying unit 12 in the short direction (Y direction) of the steel wire rope W. And a magnetic field applying unit 12b disposed on the other side (Y2 side). The magnetic field applying unit 12a and the magnetic field applying unit 12b are arranged to face each other with the steel wire rope W interposed therebetween.

  In the first embodiment, the magnetic field applying portions 11a (12a) are arranged on one side (Y direction) in the short direction (Y direction) of the steel wire rope W so as to face each other across the steel wire rope W. And the magnetic field applying portion 11b (12b) arranged on the other side (Y2 direction) in the short direction of the steel wire rope W, the N pole and the S pole of the magnetic field applying portion 11 are in the longitudinal direction of the steel wire rope W. They are arranged on the same side (in the X direction). Specifically, the magnetic field applying unit 11a and the magnetic field applying unit 11b are configured such that one side (X1 side) and the other side (X2 side) in the longitudinal direction of the steel wire rope W become an N pole and an S pole, respectively. Are located. The magnetic field applying unit 12a and the magnetic field applying unit 12b are arranged such that one side and the other side in the longitudinal direction (X direction) of the steel wire rope W are an S pole and an N pole, respectively.

  The detection unit 2 includes an excitation coil 21 and a differential coil 22, as shown in FIG. The excitation coil 21 and the differential coil 22 are wound a plurality of times along the longitudinal direction about the direction in which the steel wire rope W, which is a magnetic material made of a long material, extends, as a central axis, and the extension X of the steel wire rope W extends. It is a coil including a conductive wire portion formed to be cylindrical along a direction (longitudinal direction). That is, cylindrical coils (the differential coil 22 and the excitation coil 21) are provided so as to surround the steel wire rope W.

  The excitation coil 21 is configured to excite the state of magnetization of the steel wire rope W. More specifically, the configuration is such that a magnetic field generated based on the excitation current is applied along the X direction inside the excitation coil 21 when the excitation current flows through the excitation coil 21. Thus, the excitation coil 21 excites the state of magnetization of the steel wire rope W. Specifically, as shown in FIG. 5 (A), the direction of magnetization is adjusted in advance by the magnetic field applying unit 1, and when no magnetic field is applied by the excitation coil 21, a portion without scratches or the like The directions of magnetization of the steel wire ropes W are substantially uniform. Here, as shown in FIG. 5 (B), when an alternating current (excitation current) having a constant magnitude and a constant frequency is applied to the excitation coil 21 from the outside, in the X direction in which the steel wire rope W extends. A magnetic field is applied so as to vibrate. Further, the direction of the magnetic field (solid line or dotted line) applied by the excitation coil 21 also changes according to the direction (solid line or dotted line) of the time-varying excitation current flowing through the excitation coil 21. Therefore, the direction of magnetization of the steel wire rope W is excited by the time-varying magnetic field, and the magnetic field emitted from the steel wire rope W also changes with time. As a result, the magnetic field by the same portion of the steel wire rope W changes with time without changing the relative position between the steel wire rope W and the differential coil 22, so that the differential coil 22 for detecting a change in the magnetic field (described later) Thereby, the state of the steel wire rope W can be inspected.

  As shown in FIG. 4, in the first embodiment, the detection unit 2 is configured to acquire a detection signal based on a change in the magnetic field of the steel wire rope W after the magnetic field is applied by the magnetic field application unit 1. ing. Specifically, the detection unit 2 is configured to acquire a difference between the magnitudes of the respective detection signals generated by the two detection coils 22a and 22b included in the differential coil 22. The two detection coils 22a and 22b included in the differential coil 22 are arranged so as to be aligned with each other along the longitudinal direction (X direction) of the steel wire rope W. The detection coils 22a and 22b are an example of a “coil part” in the claims.

  Specifically, the detection coils 22a and 22b each have a length L2 in the X direction, and are arranged so as to be arranged in the X direction and without being separated from each other. Each of the detection coils 22a and 22b is configured to detect a change in the magnetic field in the X direction and generate a voltage (detection signal). The detection unit 2 is configured to acquire the difference between the magnitude of the detection signal generated by the detection coil 22a and the magnitude of the detection signal generated by the detection coil 22b as a differential signal H (see FIG. 9). ing. In the inspection device 100, the center distance L3 in the X direction between the detection coil 22a and the detection coil 22b is substantially equal to the length L2.

  FIG. 6 shows an example of a damaged steel wire rope W. In FIG. 6, how the strands are woven is shown in a simplified manner. In the steel wire rope W of FIG. 6 (A), the wire at the surface is broken. Therefore, the magnetic field leaks from the portion where the wire break has occurred. In addition, the steel wire rope W of FIG. 6 (B) has a dent on the surface due to a thread or a dent. Further, in the steel wire rope W of FIG. 6 (C), a wire break occurs inside. Since the cross-sectional areas S1, S2, and S3 at the positions where there are scratches and the like are smaller than the cross-sectional areas S0 at the portions where there are no scratches and the like, the total magnetic flux of the steel wire rope W (magnetic permeability and The value obtained by multiplying by the area) becomes smaller in a portion having a flaw or the like. As described above, since the leakage of the magnetic field and the decrease of the total magnetic flux occur, the detected magnetic field changes in a portion having a flaw or the like.

  As a result, for example, the value of the detection voltage (detection signal) of the detection coil 22a located at a location having a flaw or the like is reduced as compared with the detection coil 22b. (Differential signal H (see FIG. 9)) increases. That is, the detection signal in a portion without a flaw or the like becomes substantially zero, and the detection signal in a portion with a flaw or the like has a value larger than zero. Therefore, in the differential coil, a clear signal (S / S The signal having a good N ratio is detected as the differential signal H (see FIG. 9). Thus, the electronic circuit unit 3 (described later) can detect the presence of a scratch or the like on the steel wire rope W based on the difference between the detection signals (the differential signal H (see FIG. 9)). Also, the larger the size of the flaw or the like (the amount of reduction in the cross-sectional area), the larger the value of the detection signal and the value of the differential signal H (see FIG. 9). At the time of determination (evaluation), if there is a flaw or the like that is larger than a certain degree, it is automatically determined that the differential signal H (see FIG. 9) has exceeded a predetermined first threshold Th1 or second threshold Th2 (described later). It is possible to do. It should be noted that the flaws and the like include a change in magnetic permeability due to rust and the like, and similarly appear as a detection signal.

  As shown in FIG. 7, the electronic circuit unit 3 is configured to determine a state of the steel wire rope W made of a long material based on a signal from the differential coil 22. Includes an AC power supply 31, an amplifier 32, an AD converter 33, a CPU 34, and a digital output interface 35. The AC power supply 31 supplies (outputs) an AC current to the excitation coil 21. The amplifier 32 amplifies the differential signal H (see FIG. 9) output from the differential coil 22 and outputs the signal to the AD converter 33. The AD converter 33 converts the analog differential signal H amplified by the amplifier 32 into a digital differential signal H (see FIG. 9). The CPU 34 performs a process of removing an AC component from the differential signal H (see FIG. 9) output from the AD converter 33, and outputs a signal (DC level) corresponding to a change in the absolute value of the differential signal H (see FIG. 9). Signal), and outputs an alarm signal when the differential signal H exceeds a predetermined threshold described later. The CPU 34 controls the intensity of the current output from the AC power supply 31. The CPU 34 has a function of determining the size of a flaw or the like. The digital output interface is connected to an external PC (not shown) or the like, and outputs digital data of the processed differential signal H (see FIG. 9) and an alarm signal. In addition, the external PC stores the magnitude of the input signal in a memory, displays a graph of the magnitude of the signal with the passage of time, and, via the CPU 34, detects the magnitude of the signal from the detection unit 2 (integrated frame). The moving speed of the steel wire rope W is controlled.

  Further, when the differential signal H (see FIG. 9) output from the differential coil 22 (the detecting unit 2) exceeds the first threshold Th1, the electronic circuit unit 3 outputs the differential signal H (see FIG. 9). Outputs a first threshold signal indicating that the threshold value has exceeded the first threshold value Th1 to the outside, and when the differential signal H (see FIG. 9) output by the detection unit 2 exceeds the second threshold value Th2, It is configured to output a second threshold signal indicating that the motion signal H (see FIG. 9) has exceeded the second threshold Th2 to the outside. This makes it possible to easily determine a portion where the state of the steel wire rope W (whether there is a flaw or the like) is non-uniform based on the threshold signal. In addition, the state of the steel wire rope W having a small scratch or the like that requires attention such as follow-up observation is determined based on the first threshold signal exceeding the relatively small first threshold Th1, and the relatively large second threshold Th2 is determined. The state of the steel wire rope W having a relatively large flaw or the like that needs to be replaced immediately or the like can be determined based on the second threshold signal that has been exceeded.

  In the first embodiment, the differential coil 22 acquires the detection signal based on a change in the magnetic field of the steel wire rope W whose magnetization state is excited by the magnetic field generated by the excitation current flowing through the excitation coil 21. Is configured. Here, in the inspection device 100, the differential coil 22 is arranged so that substantially all of the magnetic field generated by the excitation coil 21 can be detected (input). Specifically, the excitation coil 21 has a length L1 substantially twice as long as the length L2 in the X direction. The X1 side end and the X2 side end of the excitation coil 21 are arranged at positions substantially equal to the X1 side end and the detection coil 22b of the detection coil 22a in the X direction, respectively.

(Comparative example)
Here, the magnetization by the magnetic field applying unit 1 of the inspection device 100 is compared with the magnetic device inspection device 101 (not shown) according to the comparative example having the same configuration except that the magnetic field applying unit 1 is not provided. Will be described.

  In the magnetic body inspection apparatus 101 (not shown) according to the comparative example in which the magnetic field application unit 1 is not provided, the excitation coil 21 applies a magnetic field in the X direction. At this time, it is necessary to increase the magnetic field applied in the X direction by the excitation coil 21 so that the differential signal H (see FIG. 9) detected in a uniform portion free from scratches and the like becomes equal. Further, since the direction of magnetization is not adjusted (aligned) in advance, the magnetic field applied in the X direction by the excitation coil 21 needs to be large enough to align the direction of magnetization substantially in the X direction.

  Here, as shown in FIG. 8, before the magnetic field is applied, the magnetization direction of the inside of the steel wire rope W, which is a magnetic material, varies depending on the internal structure at the time of manufacture. In addition, the direction of these magnetizations also changes when an external force such as stress is applied through a mechanism such as a pulley. Therefore, even in a homogeneous portion having no scratches or the like, even if the magnetization direction is excited in the X direction by the excitation coil 21, the variation in the magnetization direction cannot be completely eliminated. Variations in size and direction cause noise in the differential signal H (see FIG. 9).

  On the other hand, when the magnitude and direction of the magnetization are adjusted (aligned) by applying a magnetic field in advance, the magnetic field of a portion of the steel wire rope W where there is no flaw is detected as having a substantially constant magnitude. For this reason, it is easy to distinguish the signal from the scratch.

  The graph of FIG. 9 is a measurement waveform showing a change in the magnetic field of the steel wire rope W in the comparative example and the first embodiment. The vertical axis of the measurement waveform corresponds to the magnitude of the differential signal H (see FIG. 9), and the horizontal axis of the measurement waveform corresponds to the detection position X (the position where the steel wire rope W is detected). Since the synchronous detection and rectification processing is performed by the CPU 34, the influence of the time change of the magnetic field applied by the excitation coil 21 is eliminated.

  In the magnetic material inspection apparatus 101 according to the comparative example in which the magnetic field applying unit 1 is not provided, as shown in the measurement waveform before the magnetic shunting in FIG. Is detected. Therefore, in the magnetic body inspection apparatus 101 according to the comparative example, it is difficult for a non-specialized person without experience or knowledge (for example, a pattern of appearance of a characteristic detection signal) to determine the presence or absence of a flaw or the like. . In particular, when a threshold value or the like is provided and the determination is made based only on the magnitude of the signal, this may cause an erroneous determination.

  On the other hand, in the inspection apparatus 100 according to the first embodiment in which the magnetic field applying unit 1 is provided, almost no noise (noise) in the electronic circuit is detected as shown in the measurement waveform after the magnetic shunt in FIG. Specifically, the magnitude of the noise is relatively small, the measured waveform has a good S / N ratio, and the differential signal H is clearly shown. Therefore, the noise can be reduced by the magnetic field applying unit 1 to the extent that erroneous determination does not occur even in the case of determination by a non-expert or a threshold. In the measurement waveform after the magnetic shunt in FIG. 9, the position of the damaged portion of the steel wire rope W is shifted from one side (detection coil 22a) of the differential coil to the other side (detection coil 22b). It can be seen that the positive / negative inversion of the differential signal H (see FIG. 9) is clearly shown.

(Effect of First Embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the detection unit 2 obtains a difference (differential signal H) between the magnitudes of the respective detection signals generated in the two detection coils 22a and 22b included in the differential coil 22. It is constituted so that. As a result, different voltages (detection signals) are generated in the two detection coils 22a and 22b based on the change in the magnetic field of the steel wire rope W, so that the difference between the two detection signals (differential signal H) is obtained. By doing so, local changes in the magnetic field of the steel wire rope W can be easily detected. As a result, using the two detection coils 22a and 22b having a relatively simple structure included in the differential coil 22, the state of the steel wire rope W that generates a local magnetic field change (whether there is no flaw or the like). ) Can be inspected with a simple configuration. In addition, since the direction of magnetization of the steel wire rope W is adjusted in advance by the magnetic field applying unit 1, it is possible to inspect the state of the steel wire rope W (whether there is a flaw or the like) in a state where noise appearing in the detection signal is reduced. it can. As a result, the presence / absence of a scratch or the like on the steel wire rope W can be easily determined as compared with the case where the direction of magnetization of the steel wire rope W is not adjusted. ) Can be accurately inspected.

  In the first embodiment, as described above, the steel wire rope W is made of a long material, and the two detection coils 22a and 22b included in the differential coil 22 are connected to the long direction of the long material (X direction). ). Thus, since the two detection coils 22a and 22b are arranged so as to be aligned with each other along the longitudinal direction of the steel wire rope W, local changes in the state of the steel wire rope W (whether there is a flaw or the like) can be reduced. It can be detected along the longitudinal direction of the steel wire rope W. As a result, the state of the steel wire rope W (whether there is a scratch or the like) can be inspected along the longitudinal direction of the steel wire rope W, so that the detection unit 2 is relatively moved along the longitudinal direction of the steel wire rope W. By doing so, the entire steel wire rope W can be easily inspected.

  Further, in the first embodiment, as described above, the magnetic field application unit 1 is moved from the detection unit 2 in the longitudinal direction (X direction) of the steel wire rope W so that the output magnetic field does not affect the detection by the detection unit 2. ). Thereby, it is possible to suppress the noise caused by the magnetic field output by the magnetic field application unit 1 from being detected by the detection unit 2.

  In the first embodiment, as described above, the magnetic field applying unit 1 applies the magnetic field applied to the detecting unit 2 on one side (X1 side) in the longitudinal direction (X direction) of the steel wire rope W. And a magnetic field applying unit 12 arranged on the other side (X2 side) in the longitudinal direction of the steel wire rope W. Accordingly, the magnetic field applying unit 11 and the magnetic field applying unit 12 are arranged on one side and the other side in the longitudinal direction of the steel wire rope W, respectively. In either case, the magnetization direction can be adjusted by applying a magnetic field to the steel wire rope W in advance.

  In the first embodiment, as described above, the magnetic field applying unit 1 is opposed to the steel wire rope W with respect to the steel wire rope W such that the magnetic field applying unit 1 is opposed to the steel wire rope W with the steel wire rope W interposed therebetween. ) On one side and the other side. Accordingly, the magnetic field applying unit 1 is disposed on one side and the other side in the short direction orthogonal to the longitudinal direction of the steel wire rope W so as to face each other with the steel wire rope W interposed therebetween. The magnetic field applied to the steel wire rope W can be easily increased as compared with the case where the magnetic field application unit 1 is arranged only on one side in the short direction, so that the magnetization direction of the steel wire rope W Can be efficiently arranged.

  Further, in the first embodiment, as described above, the magnetic field applied on one side (Y1 side) in the short direction (Y direction) of the steel wire rope W so as to oppose the steel wire rope W therebetween. The parts 11a and 12a and the magnetic field applying parts 11b and 12b arranged on the other side (Y2 side) in the short side direction of the steel wire rope W are connected to the steel wire rope W by the N pole and the S pole of the magnetic field applying part 11. Are arranged on the same side in the longitudinal direction (X direction). Thereby, the same poles of the magnetic field applying portions 1 arranged on one side and the other side in the short direction of the steel wire rope W so as to face each other with the steel wire rope W interposed therebetween have the same polarity in the longitudinal direction of the steel wire rope W. Side, the direction of the magnetic field applied to the steel wire rope W by the magnetic field applying units 11a and 12a arranged on one side in the short direction of the steel wire rope W and the short side of the steel wire rope W The direction of the magnetic field applied to the steel wire rope W can be made uniform by the magnetic field applying units 11b and 12b arranged on the other side in the hand direction. As a result, the magnetic field applied to the steel wire rope W can be more easily increased, so that the direction of magnetization of the steel wire rope W can be adjusted more efficiently.

  Further, in the first embodiment, as described above, the detection unit 2 includes the excitation coil 21 for exciting the state of magnetization of the steel wire rope W, and drives the differential coil 22 through the excitation current flowing through the excitation coil 21. The detection signal is obtained based on a change in the magnetic field of the steel wire rope W whose magnetization state is excited by the magnetic field generated by the above. Thereby, the magnetization state of the steel wire rope W is excited by the excitation coil, and the magnetic field of the steel wire rope W can be changed over time. Therefore, the steel wire rope W and the detecting unit 2 can be moved without relative movement. A change in the magnetic field of the wire rope W can be detected.

[Second embodiment]
Next, a configuration of the inspection apparatus 200 according to the second embodiment will be described with reference to FIGS. The inspection device 200 according to the second embodiment is configured such that the center-to-center distance in the X direction between two detection coils included in the differential coil is smaller than that of the inspection device 100 according to the first embodiment. The inspection apparatus 200 is an example of the “magnetic body inspection apparatus” in the claims.

  As shown in FIG. 3, the inspection device 200 includes a detection unit 202 and an electronic circuit unit 203.

  As shown in FIG. 10, in the second embodiment, the detection unit 202 is generated by two detection coils 222a and 222b included in the differential coil 222, as in the detection unit 2 of the inspection device 100 of the first embodiment. It is configured to acquire the difference (the differential signal H (see FIG. 11)) between the magnitudes of the respective detection signals. Note that the detection coils 222a and 222b are examples of the "coil portion" in the claims.

  The detection coils 222a and 222b each have a length L202 in the X direction and are arranged so as to be spaced apart by a length L4 in the X direction. The two detection coils 222a and 222b of the differential coil 222 have a length L203 between centers in the longitudinal direction (X direction) of the steel wire rope W. The center-to-center distance L203 is set to be smaller than the center-to-center distance L3 of the differential coil 22 of the first embodiment. In the differential coil 22 (222), it is possible to detect a more local change in the state of the steel wire rope W (whether there is a flaw or the like) as the center-to-center distance L3 (L203) becomes smaller. .

  Here, in the second embodiment, the center-to-center distance L203 is determined by detecting the change in the magnetic field of the steel wire rope W by relatively moving the detection unit 202 in the longitudinal direction (X direction) of the steel wire rope W. Are set based on the amount of movement of the differential coil 222 during the measurement cycle of the differential coil 222.

  Specifically, the inspection apparatus 200 is configured such that the measurement cycle of the differential coil 222 has a small value of about several ms. Further, the moving speed at which the detecting unit 202 is relatively moved in the longitudinal direction of the steel wire rope W is configured to be a value of about several m / s. That is, the moving amount of the differential coil 222 during the measurement cycle of the differential coil 222 has a small value. In the inspection device 200, the center-to-center distance L203 is set to a relatively small value based on the amount of movement of the differential coil 222 during the measurement cycle of the differential coil 222.

  If the distance L203 between the centers is smaller than the amount of movement of the differential coil 222 during the measurement cycle of the differential coil 222, an undetected portion occurs in the steel wire rope W. Therefore, in the inspection device 200, the center-to-center distance L203 is substantially equal to or more than the moving amount (moving distance) of the differential coil 222 moving in the X direction during the measurement cycle of the differential coil 222, and is a relatively small value. Is set to

  For example, when the measurement cycle of the differential coil 222 is 1 ms, and the moving speed at which the differential coil 222 moves in the X direction relative to the steel wire rope W is 1 m / s, the measurement cycle of the differential coil 222 is The moving amount (moving distance) by which the differential coil 222 moves in the X direction during this time is 1 mm. In this case, the center-to-center distance L203 is set to a value larger than approximately 1 mm and relatively small (closer to 1 mm).

  As shown in FIG. 7, the electronic circuit unit 203 includes a CPU 234. Note that the CPU 234 is an example of a “signal processing unit” in the claims.

  Here, as the center-to-center distance L203 decreases, the number of turns of the detection coils 222a and 222b decreases. In this case, since the detection signals detected by the detection coils 222a and 222b are also relatively small, the differential signal H is relatively small. For this reason, in the differential coil 222, the magnitude of the noise (noise) of the electronic circuit is relatively large as compared with the measured waveform after the magnetic shunt shown in FIG. 9, as in the measured waveform shown in FIG. , S / N ratio is not good. Therefore, it is relatively difficult to determine a broken wire portion of the steel wire rope W, which causes an erroneous determination.

  Therefore, in the second embodiment, the CPU 234 determines whether the differential signal Ha obtained by the differential coil 222 at the position P1 in the longitudinal direction (X direction) of the steel wire rope W is equal to the position P2 in the longitudinal direction of the steel wire rope W. Is configured to perform a differential signal process of calculating a differential signal Hb obtained by subtracting the differential signal Ha obtained by the differential coil 222 from the differential signal Ha. The position P2 is set at a position separated by a predetermined distance dL from the position P1 in the longitudinal direction of the steel wire rope W based on the center-to-center distance L203. Further, the CPU 234 is configured to perform a difference signal process on a difference (differential signal H) in the magnitude of the detection signal on which the noise reduction process has been performed. The position P1 and the position P2 are examples of the “first position” and the “second position” in the claims, respectively. The differential signal Hb is an example of the “difference value” in the claims.

  Specifically, the CPU 234 responds to the difference in the magnitude of the detection signal (differential signal H) along the longitudinal direction of the steel wire rope W at each position in the longitudinal direction (X direction) of the steel wire rope W. A moving average process (low-pass filter process) is performed for each predetermined section dx. As a result, a measurement waveform with reduced noise is obtained, such as the measurement waveform shown in FIG. Then, the CPU 234 calculates a difference value between the differential signal Ha at the detection position X and the differential signal Ha at the detection position X at the position P2 in the measurement waveform shown in FIG. 11B. Then, the CPU 234 uses the calculated difference value as the differential signal Hb at the detection position X. The position P2 is a position where the detection position X is separated from the position P1 by a predetermined distance dL. The predetermined distance dL is set to, for example, about several times the center distance L203. In FIG. 11B, only one position P1 (and position P2) is shown, but the difference signal processing is performed over the entire measurement waveform (that is, the position P1 is located at the side of the measurement waveform. Each position of the axis). That is, by the differential signal processing, a portion where the differential signal Ha changes greatly in the measurement waveform shown in FIG. 11B is extracted as a large differential signal Hb.

  Further, in the second embodiment, the CPU 234 is configured to further perform signal processing for setting a negative value to zero in the calculated differential signal Hb in the differential signal processing. That is, by the signal processing for setting the negative value of the differential signal Hb to zero, only the portion where the differential signal Ha increases is extracted as the differential signal Hb. As a result, in the measurement waveform shown in FIG. 11B, of the portions where the negative-side convex portion and the positive-side convex portion of the differential signal Ha are adjacent to each other, the negative-side convex portion of the differential signal Ha is convex. The portion (part A) where the differential signal Ha changes greatly from the top of the portion to the top of the portion convex on the positive side is extracted as a large differential signal Hb in the measurement waveform shown in FIG. Is done.

  Other configurations of the second embodiment are the same as those of the first embodiment.

(Effect of Second Embodiment)
In the second embodiment, as described above, the detection unit 202 obtains the difference (the differential signal H) between the magnitudes of the respective detection signals generated in the two detection coils 222a and 222b included in the differential coil 222. It is constituted so that. As a result, different voltages (detection signals) are generated in the two detection coils 222a and 222b based on the change in the magnetic field of the steel wire rope W, so that the difference between the two detection signals (differential signal H) is obtained. By doing so, local changes in the magnetic field of the steel wire rope W can be easily detected. As a result, similarly to the first embodiment, a steel wire that generates a local magnetic field change by using two detection coils 222a and 222b having a relatively simple structure included in the differential coil 222 is used. The state of the rope W (whether there is a scratch or the like) can be inspected with a simple configuration.

  In the second embodiment, as described above, the center-to-center distance L203 of the two detection coils 222a and 222b of the differential coil 222 in the longitudinal direction (X direction) of the steel wire rope W is determined by setting the detection unit 202 to the steel wire rope W. Are set based on the amount of movement of the differential coil 222 during the measurement cycle of the differential coil 222 when detecting a change in the magnetic field of the steel wire rope W by relatively moving in the longitudinal direction. Accordingly, when the measurement cycle of the differential coil 222 is set to a small value of about several ms, the amount of movement of the differential coil 222 during the measurement cycle of the differential coil 222 also becomes a small value. Since the center-to-center distance L203 of the two detection coils 222a and 222b in the longitudinal direction of the steel wire rope W becomes small, it is possible to reliably detect a local change in the state (whether there is a flaw or the like) of the steel wire rope W. it can.

  Further, in the second embodiment, as described above, the inspection apparatus 100 determines the difference (difference) in the magnitude of the detection signal acquired by the differential coil 222 at the position P1 in the longitudinal direction (X direction) of the steel wire rope W. The differential signal Hb is calculated by subtracting the dynamic signal H) from a difference (differential signal H) in the magnitude of the detection signal acquired by the differential coil 222 at the position P2 in the longitudinal direction of the steel wire rope W. It includes a CPU 234 that performs difference signal processing. The position P2 is a predetermined distance dL from the position P1 in the longitudinal direction of the steel wire rope W based on the center-to-center distance L203 in the longitudinal direction of the steel wire rope W between the two detection coils 222a and 222b of the differential coil 222. It is far away. Accordingly, in the measurement waveform in which the longitudinal position of the steel wire rope W is shown on the horizontal axis and the difference in the magnitude of the detection signal (differential signal H) acquired by the differential coil 222 is shown on the vertical axis, the steel wire rope W A portion where the differential signal H greatly changes with respect to a change in the position of W in the longitudinal direction can be extracted as a large differential signal Hb. Thereby, when the steel wire rope W has a flaw or the like, a portion of the differential signal H appearing in the measurement waveform, in which the negatively convex portion and the positively convex portion are adjacent to each other, is easily extracted. be able to. As a result, even if the measurement waveform is not adjusted (including noise) due to the magnetization direction of the steel wire rope W being not sufficiently adjusted, the state of the steel wire rope W (whether or not there is a flaw) is determined. Local changes can be easily detected.

  In the second embodiment, as described above, the CPU 234 is configured to perform signal processing for setting the negative value of the differential signal Hb to zero. Thereby, when taking the difference from the side having the convex portion on the positive side of the differential signal H to the side having the convex portion on the negative side in the measurement waveform, the positive portion of the differential signal H is A portion where the differential signal H particularly greatly changes from the top of the negatively convex portion of the differential signal H to the top of the positively convex portion of the differential signal H among the portions where the convex portion is adjacent (part) A) can be extracted. As a result, even when the measurement waveform is not adjusted due to the magnetization direction of the steel wire rope W being not sufficiently adjusted, the local change of the state of the steel wire rope W (whether there is a flaw or the like) can be further improved. It can be easily detected.

  In the second embodiment, as described above, the CPU 234 is configured to perform the difference signal processing on the difference (the differential signal H) in the magnitude of the detection signal subjected to the noise reduction processing. Thus, the differential signal processing can be performed while reducing the influence of the disturbance of the measurement waveform caused by the noise (noise) of the electronic circuit. As a result, even when the noise of the electronic circuit is detected due to a reduction in the center-to-center distance L203 in the longitudinal direction of the steel wire rope W between the two detection coils 222a and 222b of the differential coil 222, even if the electronic circuit noise is detected. In a state where the influence of noise is reduced, a portion where the differential signal H greatly changes with respect to a change in the position of the steel wire rope W in the longitudinal direction can be extracted as the differential signal Hb in the measurement waveform.

  Other effects of the second embodiment are similar to those of the first embodiment.

[Modification]
It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and includes all equivalents (modifications) within the scope and meaning equivalent to the claims.

  For example, in the above-described first and second embodiments, an example has been described in which the magnetic material is a long material, but the present invention is not limited to this. In the present invention, the magnetic body may be, for example, a thin plate other than a long material, an iron ball (bearing), or the like. In addition, the present invention can be used for inspection of all magnetic materials having a uniform structure. Further, when the magnetic body is a thin plate or the like, it may be configured to detect a change in a magnetic field in a direction in which a surface of the thin plate or the like extends.

  Further, in the first and second embodiments, the example in which the magnetic material made of the long material is the steel wire rope W has been described, but the present invention is not limited to this. In the present invention, for example, the magnetic material made of a long material may be a thin plate, a square material, a cylindrical pipe, a wire, a chain, or the like.

  Further, in the first and second embodiments, an example has been described in which the magnetic field applying unit 1 is configured to be fixed to the frame F together with the detecting unit 2 as the inspection unit U, but the present invention is not limited to this. I can't. In the present invention, the relative position between the magnetic field application unit 1 and the detection unit 2 may be configured to be changeable. Specifically, after the magnetization direction of the steel wire rope W is adjusted by the magnetic field application unit 1, only the magnetic field application unit 1 may be moved to a position away from the steel wire rope W. Accordingly, when the detection unit 2 detects a change in the magnetic field of the steel wire rope W, the detection unit 2 can be easily separated so that the magnetic field of the magnetic field application unit 1 does not affect the detection unit 2.

  Further, in the first and second embodiments, the example in which the magnetic field applying unit 1 is configured by the permanent magnet has been described, but the present invention is not limited to this. In the present invention, the magnetic field applying unit may be constituted by an electromagnet (coil).

  In the first and second embodiments, when a magnetic field is applied to the steel wire rope W in advance, the configuration of the magnetic field application unit 1 may be configured as shown in FIG. Specifically, like the magnetic field applying unit 1A shown in FIG. 12A, the magnetic field applying unit 11 and the magnetic field applying unit 12A may be arranged such that the same pole is on the same side in the X direction. . Further, like the magnetic field applying unit 1B shown in FIG. 12B and the magnetic field applying unit 1D shown in FIG. 12D, the magnetic field applying unit is provided only on one side of the detecting unit 2 in the longitudinal direction of the steel wire rope W. It may be configured to be provided. Also, like the magnetic field applying unit 1C shown in FIG. 12C and the magnetic field applying unit 1D shown in FIG. 12D, the magnetic field applying unit is provided only on one side in the short direction of the steel wire rope W. You may comprise. Also, as shown in FIG. 12 (E), the magnetic field applying unit 1E (11E, 12E) and the magnetic field applying unit 1F (11F, 12F) shown in FIG. On one side and the other side in the hand direction, the north pole and the south pole may be arranged so as to be opposite sides in the X direction. The magnetic field applying units 11E and 11F are examples of the “first magnetic field applying unit” in the claims. The magnetic field applying units 12A, 12E, and 12F are examples of the “second magnetic field applying unit” in the claims.

  In the first and second embodiments, the configuration of the detection unit 2 that acquires a detection signal based on a change in the magnetic field of the steel wire rope W in a state where the magnetic field is applied by the magnetic field application unit 1 is shown in FIG. The configuration as shown may be adopted. Specifically, as shown in a detection unit 2A shown in FIG. 13A, the two detection coils 22Aa and 22Ab are separated from each other in the X direction, and one end (X1 side) of the detection coil 22Aa. The end of the other side (X2 side) of the detection coil 22Ab and the end of the other side (X1 side) of the excitation coil 21 are substantially equal to the end of the other side (X2 side) in the X direction. It may be constituted so that it may become. Further, as in a detection unit 2B shown in FIG. 13B, the two detection coils 22Ba and 22Bb are not separated from each other in the X direction, and one end (X1 side) of the detection coil 22Ba and the detection coil 22Bb. Of the excitation coil 21 is closer to the X2 side than the end of the excitation coil 21 (the X1 side) and is closer to the X1 side than the end of the other side (the X2 side). May be. Further, as in a detection unit 2C shown in FIG. 13C, an excitation coil 21C may be arranged between two detection coils 22Ca and 22Cb of the differential coil 22C. Further, as in the detection unit 2D illustrated in FIG. 13D and the detection unit 2E illustrated in FIG. 13E, the excitation coil may not be included. The detection coils 22Aa, 22Ab, 22Ba, 22Bb, 22Ca and 22Cb are examples of the "coil portion" in the claims.

  Further, in the first and second embodiments, the example in which the cylindrical coils (the differential coil 22 (222) and the excitation coil 21) are provided so as to surround the steel wire rope W has been described. Is not limited to this. In the present invention, as shown in FIG. 14, the detection coil 322 and the excitation coil may have a rectangular cylindrical shape. Further, as shown in FIG. 15, the detection coil 422 and the excitation coil are arranged at positions separated from the steel wire rope W so as not to surround the steel wire rope W but to detect a change in a magnetic field in a direction along the steel wire rope W. May be.

  Further, in the first and second embodiments, an example is described in which the inspection device 100 (200) is configured to be movable along the steel wire rope W, but the present invention is not limited to this. In the present invention, the inspection device may be configured not to move. In this case, the inspection device detects a change in the magnetic field of the steel wire rope W passing inside or near the fixed position.

  Further, in the first and second embodiments, the electronic circuit unit 3 (203) determines whether the differential signal H output from the differential coil (detection unit) is equal to the predetermined threshold value (the first threshold value Th1 and the second threshold value). Although an example has been described in which a signal is output to the outside when the threshold value Th2) is exceeded, the present invention is not limited to this. In the present invention, the electronic circuit unit counts the number N of times when the differential signal H exceeds the threshold Th, and when the counted number N exceeds the predetermined number M, the counted number N is increased to the predetermined number M. A signal indicating that the number M has been exceeded may be output to the outside. Thereby, the electronic circuit unit can count the number N of times exceeding the threshold Th and determine the deterioration state of the steel wire rope W based on the number of scratches or the like. Further, by comparing the number N of times exceeding the threshold value Th in the previous measurement with the number N of times exceeding the threshold value Th in the current measurement, the change over time of the state of the presence or absence of a scratch or the like on the steel wire rope W (for example, , Degradation progress speed) may be determined. Further, the number of the predetermined thresholds may be one or plural (for example, three) other than two.

  In the first and second embodiments, an example has been described in which the excitation current (alternating current) that changes over time flows through the excitation coil 21, but the present invention is not limited to this. In the present invention, a configuration may be such that a current (DC current) that does not change over time flows through the excitation coil 21. In this case, the detection unit 2 (202) is moved relative to the steel wire rope W at a constant speed that is substantially constant in the X direction, so that the steel wire rope W at the detection position of the detection unit 2 in the X direction is moved. It is possible to detect a change in the magnetic field.

  Further, in the second embodiment, an example has been described in which the CPU 234 is configured to perform the difference signal processing on the difference (the differential signal H) in the magnitude of the detection signal subjected to the noise reduction processing. However, the present invention is not limited to this. In the present invention, the CPU may be configured to perform the difference signal processing on the difference (the differential signal H) of the magnitude of the detection signal acquired by the detection unit without performing the noise reduction processing. .

  In the second embodiment, an example is shown in which moving average processing is performed along the longitudinal direction of the steel wire rope W as noise reduction processing for the difference in the magnitude of the detection signal (differential signal H). However, the present invention is not limited to this. In the present invention, a configuration may be adopted in which noise reduction processing is performed on the difference between the magnitudes of the detection signals (differential signal H) by a method other than the moving average processing.

  Further, in the second embodiment, an example has been described in which the CPU 234 is configured to further perform signal processing for setting the negative value of the calculated differential signal Hb to zero in the differential signal processing. However, the present invention is not limited to this. In the present invention, the CPU may be configured not to perform the signal processing for setting the negative value of the calculated differential signal Hb to zero in the differential signal processing.

  Further, in the second embodiment, the CPU 234 is configured to determine the difference between the differential signal H acquired by the differential coil 222 at the position P1 in the longitudinal direction (X direction) of the steel wire rope W and the longitudinal position of the steel wire rope W. Although an example has been described in which the differential signal processing for calculating the differential signal Hb obtained by subtracting the differential signal H obtained by the differential coil 222 in P2 is performed, the present invention is not limited to this. In the present invention, the CPU may be configured not to perform the difference signal processing. In this case, as in the first embodiment, the state of the steel wire rope W (whether there is a flaw or the like) is inspected based on the difference (the differential signal H) in the magnitude of the detection signal acquired by the detection unit.

  Further, in the first and second embodiments, an example in which the inspection apparatus 100 (200) is used for a mobile X-ray imaging apparatus (a round-trip car) has been described, but the present invention is not limited to this. In the present invention, a stationary X-ray irradiator (X-ray imaging apparatus) 901 shown in FIG. 16A and a stand-type X-ray irradiator (X) shown in FIG. X-ray imaging device) 902 and a stand-type X-ray detection device (X-ray imaging device) 903 shown in FIG. Furthermore, the present invention is also applicable to devices and infrastructure using wires, for example, moving devices such as elevators and ropeways, and wire portions such as suspension bridges and piers. Further, the present invention can be applied not only to wires but also to any use for measuring damage to a magnetic body, such as electric poles, water and sewage pipes, gas pipes, and pipelines. The X-ray irradiator E11 in FIG. 16A and the X-ray irradiator E12 in FIG. 16B both include an X-ray tube or the like and irradiate X-rays. The line detector E23 is a part that detects X-rays including an FPD (flat panel detector) and the like. Further, the X-ray irradiator E11, the X-ray irradiator E12, and the X-ray detector E23 are each supported by being pulled by the steel wire rope W. 16A to 16C, the inspection apparatus 100 (200) is configured to be movable along the steel wire rope W.

  In the first and second embodiments, the scratches on the surface of the magnetic body (steel wire rope W) are mainly detected as the "scratch etc." of the magnetic body (steel wire rope W). If the wire rope is not complete, but the wire is broken, the change in thickness, corrosion (rust), cracks, and uneven magnetic permeability are also included in the detection target. The detection target is not limited to the surface of the magnetic material (steel wire rope W), but may be inside. In addition, if a magnetic field of the magnetic material (steel wire rope W) or a state that causes non-uniformity of the magnetic field is detected, it can be detected as a “state of the magnetic material”.

  In the claims, “change in magnetic field of a magnetic material” includes, in addition to a change in a magnetic field observed near a magnetic material to which a magnetic field is applied when an external magnetic field is applied, an external magnetic field. This also includes a change in the magnetic field caused by the magnetic substance itself when no voltage is applied.

1, 1A, 1B, 1C, 1D, 1E, 1F Magnetic field applying section 11 (11a, 11b), 11E, 11F Magnetic field applying section (first magnetic field applying section)
12 (12a, 12b), 12A, 12E, 12F Magnetic field applying section (second magnetic field applying section)
2, 203, 2A, 2B, 2C, 2D, 2E Detector 21, 21C Excitation coil 22, 222, 22A, 22B, 22C, 22D, 22E, 322, 422 Differential coil 22a, 22b, 222a, 222b, 22Aa, 22Ab, 22Ba, 22Bb, 22Ca, 22Cb Detection coil (coil part)
303 Electronic circuit unit 234 CPU (signal processing unit)
100, 200 inspection device (magnetic device inspection device)
H Differential signal (difference in detection signal magnitude)
Hb differential signal (difference value)
L203 Center-to-center distance (in the longitudinal direction of the magnetic body of the two coil portions) P1 position (first position)
P2 position (second position)
W steel wire rope (magnetic material, long material)
dL predetermined distance

Claims (11)

A magnetic field applying unit for applying a magnetic field in advance to a magnetic body to be inspected and adjusting the direction of magnetization of the magnetic body;
After a magnetic field is applied by the magnetic field application unit, a detection unit that acquires a detection signal based on a change in the magnetic field of the magnetic body,
The magnetic field applying unit is arranged so that the N pole and the S pole of the magnetic field applying unit are along the longitudinal direction of the magnetic body,
The magnetic body inspection apparatus, wherein the detection unit includes a differential coil, and is configured to acquire a difference between magnitudes of the respective detection signals generated by two coil portions included in the differential coil. .   The center-to-center distance between the two coil portions of the differential coil in the longitudinal direction of the magnetic body detects a change in the magnetic field of the magnetic body by relatively moving the detection unit in the longitudinal direction of the magnetic body. The magnetic body inspection apparatus according to claim 1, wherein the setting is performed based on an amount of movement of the differential coil during a measurement cycle of the differential coil.   A difference between the magnitude of the detection signal acquired by the differential coil at the first position in the longitudinal direction of the magnetic body and the distance between the centers of the two coil portions of the differential coil in the longitudinal direction of the magnetic body; A difference between a magnitude of the detection signal acquired by the differential coil at a second position separated by a predetermined distance from the first position in the longitudinal direction of the magnetic body based on the distance; The magnetic body inspection device according to claim 2, further comprising a signal processing unit that performs a difference signal process for calculating a value.   The magnetic signal inspection apparatus according to claim 3, wherein the signal processing unit is configured to perform signal processing for setting a negative value of the difference value to zero.   The inspection of a magnetic body according to claim 3, wherein the signal processing unit is configured to perform the difference signal processing on a difference in the magnitude of the detection signal on which the noise reduction processing has been performed. apparatus. The magnetic body is made of a long material,
The inspection of a magnetic body according to claim 1, wherein the two coil portions included in the differential coil are arranged so as to be arranged side by side along a longitudinal direction of the long material. apparatus.   7. The magnetic field application unit according to claim 1, wherein the output magnetic field does not affect detection by the detection unit, and is provided at a position separated from the detection unit in a longitudinal direction of the magnetic body. 8. The inspection device for a magnetic body according to claim 1.   The magnetic field applying unit includes a first magnetic field applying unit disposed on one side in the longitudinal direction of the magnetic body with respect to the detecting unit, and a second magnetic field applying unit disposed on the other side in the longitudinal direction of the magnetic body. The magnetic body inspection apparatus according to any one of claims 1 to 7, further comprising a unit.   9. The magnetic field applying unit according to claim 1, wherein the magnetic field applying unit is disposed on one side and the other side of the magnetic body in a lateral direction of the magnetic body so as to face each other across the magnetic body. The inspection device for a magnetic body according to claim 1.   The magnetic field applying unit disposed on one side in the short direction of the magnetic body, and the magnetic field applying unit disposed on the other side in the short direction of the magnetic body so as to face the magnetic body. The magnetic body inspection apparatus according to claim 9, wherein the N-pole and the S-pole of the magnetic field applying unit are arranged such that they are on the same side in the longitudinal direction of the magnetic body. The detection unit further includes an excitation coil for exciting the state of magnetization of the magnetic body,
The differential coil is configured to acquire the detection signal based on a change in a magnetic field of the magnetic body whose magnetization state is excited by a magnetic field generated by an excitation current flowing through the excitation coil. The inspection device for a magnetic body according to any one of claims 1 to 10.

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