JP2017138099A - Nondestructive inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of inspection or lateral resolution in a nondestructive inspection apparatus using an exciting coil and a plurality of magnetic sensors to detect a defect in piping.SOLUTION: A nondestructive inspection apparatus includes: a movable inspection part 12 that loads exciting coils 3-1, 3-2 and magnetic sensors a01, b01, and is disposed outside piping 2 to be inspected and moves in an axial direction of the piping to be inspected; and control means 10 for controlling a traveling speed of the movable inspection part, voltage applied to the exciting coils, and the magnetic sensors. The exciting coils are composed of a pair into which the piping to be inspected is inserted while the pair is disposed mutually separately in an axial direction. One or a plurality of magnetic sensors are disposed in a circumferential direction of the piping to be inspected between the exciting coils mutually separated in the axial direction, and are disposed in positions separated at least by predetermined distance in an axial direction. Reliability is improved by detecting the same place by different magnetic sensors with a time difference by movement of the movable inspection part 12, and lateral resolution is improved by performing detection simultaneously by using a plurality of magnetic sensors and performing correction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nondestructive inspection apparatus.

  Conventionally, as a method for inspecting a defect in a steel material, there are an eddy current flaw detection method and a magnetic flux leakage flaw detection method using magnetism. In the eddy current flaw detection method, an alternating magnetic field is applied to a measurement object, and a change in eddy current generated in the measurement object is observed. That is, when an alternating magnetic field is applied to the measurement target, the distribution of eddy current changes in the portion having a defect relative to the portion having no defect in the measurement target, so the magnetic field generated by the eddy current also changes. A defect inspection is performed by detecting a change in the eddy current by a magnetic sensor such as a search coil or a magnetoresistive element (MR). On the other hand, in the leakage magnetic flux flaw detection method, a DC or AC magnetic field is applied to an object to be measured, and a magnetic flux leaking from a defective portion is detected by a search coil or a magnetic sensor.

Patent Document 1 describes a nondestructive inspection apparatus using pulse magnetism.
Specifically, Patent Document 1 discloses a nondestructive inspection apparatus using pulse magnetism for nondestructive inspection of a defect in a pipe to be inspected, which is inserted through the pipe to be inspected and arranged at an arbitrary position with respect to the pipe to be inspected. A pair of possible excitation coils, a pulse power source that applies a pulse voltage to at least one of the pair of excitation coils, and an outer peripheral surface of the pipe to be inspected, disposed between the pair of excitation coils, A magnetic sensor that detects a magnetic field parallel to the central axis direction and a pulse magnetic field that is generated when at least one of a pair of excitation coils is driven by a pulse power source is detected by the magnetic sensor, and the pulse magnetic field detected by the magnetic sensor is detected. And a non-destructive inspection apparatus using pulse magnetism, characterized in that it comprises means for analyzing the response.
According to such a nondestructive inspection apparatus, a magnetic field in the direction of the central axis of the pipe to be inspected can be applied to a predetermined location of the pipe to be inspected by a pair of exciting coils inserted through the pipe to be inspected. Further, by providing a magnetic sensor arranged between the pair of exciting coils on the outer peripheral surface of the pipe to be inspected, a magnetic field parallel to the central axis direction of the pipe to be inspected can be detected. The magnetic field generated by the exciting coil travels through the pipe to be inspected to the magnetic sensor. In the middle, the magnetic field in the direction of the central axis of the pipe to be inspected leaks to the outside, but the magnetic field propagated by corrosion and defects differs. Here, when the excitation coil is driven by a pulse power source and the generated magnetic field is a pulsed magnetic field, the rising magnetic signal detected by the magnetic sensor is timed at the time of rising of the pulsed magnetic field and the time zone during which a constant magnetic field is applied thereafter. Attenuates with. By analyzing the peak value and attenuation characteristics of the detected pulse magnetic signal, it is possible to detect defects such as corrosion and cracks in the pipe with higher accuracy.

  Further, in paragraph 0046 of Patent Document 1, a plurality of magnetic sensors are arranged in the circumferential direction at a central portion equidistant from the pair of exciting coils, and the spatial resolution can be improved as the number of magnetic sensors increases. In addition, it is also described that surface data can be obtained and mapped by moving the inspection section equipped with the excitation coil and the magnetic sensor in a state where the inspection pipe is inserted and performing multipoint measurement.

JP 2014-044087 A

However, the above prior art has the following problems.
In the configuration in which the plurality of magnetic sensors described in Patent Document 1 are arranged in the circumferential direction, the plurality of magnetic sensors are arranged in the circumferential direction at a central portion equidistant from the pair of excitation coils. There is only one row of magnetic sensors.
By the way, the inspection object is piping arranged in a plant or the like, and inspection on site is required.
In that case, not only the magnetism caused by the natural environment of the inspection site due to geomagnetism or earthquakes, but also the magnetism generated from an artificial object such as an electromagnetic device becomes noise, and a weak pulse magnetic signal for inspection through the pipe is generated. It can be difficult to detect accurately.
In order to improve the reliability of the detection signal of the magnetic sensor in such a noise environment, it is conceivable to detect a pulse magnetic signal for inspection at the same point multiple times with the magnetic sensor. However, in the invention described in Patent Document 1, when an inspection unit equipped with an exciting coil and a magnetic sensor is moved in a state in which a pipe to be inspected is inserted to perform multipoint measurement, a stop time at the same point is required. Therefore, it takes a long time to move a certain distance in the axial direction of the pipe to be inspected, and the inspection time increases.
Further, in the invention described in Patent Document 1, as described in the same document, if the number of magnetic sensors arranged in the circumferential direction is increased, the spatial resolution is improved, but the magnetic sensors arranged in the circumferential direction are improved. Since the pitch determines the spatial resolution, the resolution cannot be further improved, and even if the gap between the magnetic sensors is zero, a resolution finer than the dimension of the magnetic sensor along the circumferential direction cannot be achieved. It becomes. On the other hand, it is possible to reduce the drive wiring and drive circuit of the magnetic sensor by opening a gap between the magnetic sensors.

  The present invention has been made in view of the problems in the prior art described above. In the nondestructive inspection apparatus that uses an exciting coil and a plurality of magnetic sensors to detect a defect in piping, the reliability of inspection or spatial resolution is improved. The challenge is to improve.

Invention of Claim 1 for solving the above subject is a nondestructive inspection device using magnetism which carries out a nondestructive inspection of the defect of piping to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils that are separated from each other in the axial direction, and a plurality of magnetic sensors are arranged at least at a predetermined distance in the axial direction. Consists of
The control means controls the non-destructive inspection so that a period of the voltage or an integral multiple of 2 or more thereof is equal to a time required for the movable inspection unit to move by the predetermined distance. Device.

  According to a second aspect of the present invention, one or two or more magnetic sensors are arranged in a section between a plurality of magnetic sensors arranged at a position separated by the predetermined distance, and the magnetic sensor is arranged in the section between the two. The nondestructive inspection apparatus according to claim 1, wherein another magnetic sensor is disposed at a position spaced apart from the first predetermined distance in the axial direction.

The invention according to claim 3 comprises analysis means for analyzing the signal detected by the magnetic sensor,
The analysis means uses the same position as a measurement point based on a set of signals detected by a plurality of magnetic sensors arranged at different positions arranged at different timings at a certain position on the pipe to be inspected. 3. The nondestructive inspection apparatus according to claim 1, wherein a signal resulting from the defect is analyzed.

  The invention according to claim 4 is characterized in that the analysis means detects the noise based on the assumption that the waveforms of the signals included in the set are similar if there is no noise. 3 is a nondestructive inspection apparatus.

The invention according to claim 5 is a non-destructive inspection apparatus using magnetism for non-destructive inspection of a defect of a pipe to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
The magnetic sensor comprises a plurality of circumferential rows arranged in the circumferential direction of the pipe to be inspected between the excitation coils separated from each other in the axial direction, and the circumferential rows are arranged in the circumferential direction. The non-destructive inspection apparatus is configured to include two or more rows, and each magnetic sensor belonging to the row is offset in the circumferential direction with respect to the magnetic sensors belonging to other adjacent rows.

The invention according to claim 6 is a nondestructive inspection device using magnetism for nondestructive inspection of a defect of a pipe to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
The magnetic sensor is composed of a plurality arranged in the circumferential direction and / or the axial direction of the pipe to be inspected between the exciting coils separated from each other in the axial direction.
The plurality of magnetic sensors include a magnetic sensor that detects a magnetic field in a direction parallel to a central axis of the pipe to be inspected, a magnetic sensor that detects a magnetic field in a direction having a twist angle with respect to the central axis, and / or the center. A non-destructive inspection apparatus including a magnetic sensor for detecting a magnetic field in a direction parallel to a straight line intersecting with an axis.

  The invention according to claim 7 is a magnetic sensor for detecting a magnetic field in a direction parallel to a central axis of the pipe to be inspected, a magnetic sensor for detecting a magnetic field in a direction having a twist angle with respect to the central axis, and / or the center. The nondestructive inspection apparatus according to claim 6, wherein magnetic sensors that detect a magnetic field in a direction parallel to a straight line intersecting the axis are alternately arranged in the circumferential direction or the axial direction. .

The invention according to claim 8 is a nondestructive inspection apparatus using magnetism for nondestructive inspection of a defect of a pipe to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils that are separated from each other in the axial direction, and a plurality of magnetic sensors are arranged at least at a predetermined distance in the axial direction. The nondestructive inspection apparatus is characterized in that the predetermined distance is movably supported so as to be changeable.

The invention according to claim 9 is a nondestructive inspection apparatus using magnetism for nondestructive inspection of a defect in a pipe to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils separated from each other in the axial direction, and arranged at least in the axial direction,
The control means is a non-destructive inspection apparatus that is used for detecting a magnetic field for detecting the defect by selecting from the magnetic sensors arranged in the axial direction.

  According to the invention according to any one of claims 1 to 4, different magnetic sensors are sequentially placed at the same position on the pipe to be inspected by moving the movable inspection portion on which the excitation coil and the magnetic sensor are mounted. The reliability of the inspection can be improved by arranging and performing the detection of the magnetic field, and analyzing based on a plurality of detection signals obtained for the same location.

  According to the invention of claim 5, in addition to the position where the magnetic sensor is arranged, the detection signal at the position where the magnetic sensor is not arranged can be interpolated based on the detection signal of the surrounding magnetic sensor, Spatial resolution can be improved.

  According to the present invention according to claim 6 or claim 7, the signal caused by the defect of the pipe to be inspected can be detected by a magnetic sensor that detects a magnetic field in a direction parallel to the central axis of the pipe to be inspected. Since the disturbance magnetic field is not limited to this direction, it is detected by a magnetic sensor that detects a magnetic field in a direction having a twist angle with respect to the central axis and / or a magnetic sensor that detects a magnetic field in a direction parallel to a straight line intersecting the central axis. It is possible to discriminate the disturbance magnetic field and improve the reliability of the inspection.

  According to the invention according to claim 8 of the present invention, the magnetic sensor is moved as in the invention according to any one of claims 1 to 4 by changing the arrangement interval of the magnetic sensors in the axial direction of the pipe to be inspected. In addition to being able to respond to changes in speed and spatial resolution, it is possible to detect a magnetic field by arranging a magnetic sensor at an arbitrary position between excitation coils.

  According to the invention according to claim 9 of the present invention, the magnetic sensor is selected from the magnetic sensors arranged in the axial direction of the pipe to be inspected and used for detecting a magnetic field for detecting a defect. As in the invention according to any one of the four, it is possible to change the interval between magnetic sensors to be used in response to the change of the moving speed, to change the spatial resolution, and between the exciting coils. The magnetic field can be detected by selecting a magnetic sensor at an arbitrary position.

It is the schematic which shows the basic composition of the nondestructive inspection apparatus which concerns on 1st Embodiment of this invention. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on the example of 1 structure of 2nd Embodiment of this invention. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on another structural example of 2nd Embodiment of this invention. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on another structural example of 2nd Embodiment of this invention. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on another structural example of 2nd Embodiment of this invention. (A) is a top view which shows sensor arrangement | positioning of the nondestructive inspection apparatus which concerns on the example of 1 structure of 3rd Embodiment of this invention. (B) is a top view which shows sensor arrangement | positioning of the nondestructive inspection apparatus which concerns on another example of 1 structure of 3rd Embodiment of this invention. The top view (a1) and arrow B figure (a2) which show the sensor arrangement | positioning of the nondestructive inspection apparatus which concerns on another one structural example of 3rd Embodiment of this invention, and 1 other of 3rd Embodiment of this invention It is a top view (b1) and arrow C figure (b2) which show sensor arrangement | positioning of the nondestructive inspection apparatus which concerns on a structural example. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on the example of 1 structure of 4th Embodiment of this invention. It is the schematic which shows the principal part of the nondestructive inspection apparatus which concerns on the other one structural example of 4th Embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

[First Embodiment]
First, the first embodiment will be described.
FIG. 1 is a schematic diagram showing a basic configuration of a nondestructive inspection apparatus 1 using pulse magnetism (hereinafter referred to as a pulse magnetic inspection apparatus 1) according to a first embodiment of the present invention.
The pulse magnetic inspection apparatus 1 is a nondestructive inspection apparatus that detects a defect in the heat insulation pipe 2 by applying a pulse magnetic field to the heat insulation pipe 2 and detecting a change in the pulse magnetic field flowing through the heat insulation pipe 2. Coils 3-1 and 3-2, annular magnetic sensor units 4 a and 4 b, a cylindrical self-propelled moving body 5, a driving circuit 6 for traveling, a circuit 7 for magnetic sensor, a pulse power supply 8, A power supply switching circuit 9 and a computer 10 functioning as control means and analysis means are provided.

The self-propelled moving body 5 includes excitation coils 3-1 and 3-2, magnetic sensor units 4 a and 4 b, a driving circuit 6 for driving, a circuit 7 for magnetic sensor, a pulse power supply 8, and a power supply switching circuit 9. And the computer 10 is mounted and the movable test | inspection part 12 is comprised. That is, the movable inspection unit 12 is disposed outside the heat insulating pipe 2 and moves in the axial direction of the heat insulating pipe 2. Hereinafter, the axial direction of the heat insulation pipe 2 is simply referred to as “axial direction”, and the circumferential direction of the heat insulation pipe 2 is simply referred to as “circumferential direction”.
Although not shown, in order to move the movable inspection unit 12, the self-propelled moving body 5 is in contact with the motor driven by the driving circuit 6 for traveling and the outer surface of the heat insulating pipe 2 to support the entire movable inspection unit 12. The vehicle includes a plurality of traveling wheels and the like, and is configured to travel along the heat insulating pipe 2 by rotationally driving all or an appropriate part of the traveling wheels by the rotational force of the motor.
In accordance with a control signal input from the computer 10 to the driving circuit 6 for traveling, the position and moving speed of the movable inspection unit 12 along the axial direction are controlled. As a result, the positions and moving speeds of the exciting coils 3-1 and 3-2 and the magnetic sensor with respect to the heat insulating pipe 2 are controlled.

  The exciting coils 3-1 and 3-2 are configured by pairs in which the heat insulating pipe 2 is inserted and are separated from each other in the axial direction, and are arbitrarily arranged with respect to the heat insulating pipe 2 as the movable inspection unit 12 moves. It can be arranged at the position.

Each of the magnetic sensor units 4a and 4b is configured in an annular shape, and the heat insulating pipe 2 is inserted therethrough.
In the magnetic sensor unit 4a, a plurality of magnetic sensors a (a01, a02,... A09...) Are arranged side by side in the circumferential direction. In addition, in order to specify each magnetic sensor on the magnetic sensor unit 4a, the symbols a01, a02,... Are used.
Similarly, in the magnetic sensor unit 4b, a plurality of magnetic sensors b (b01, b02,... B09...) Are arranged side by side in the circumferential direction. Similarly, the symbols b01, b02,... Are used to specify individual magnetic sensors on the magnetic sensor unit 4b, and when the individual sensors are not specified, they are referred to as “magnetic sensors b”.
The magnetic sensors a and b are disposed between the pair of exciting coils 3-1 and 3-2 on the outer peripheral surface of the heat insulating pipe 2, and detect a magnetic field in a direction parallel to the central axis of the heat insulating pipe 2.
The magnetic sensor units 4a and 4b are arranged at positions spaced apart from each other by a predetermined distance in the axial direction, so that the magnetic sensor a and the magnetic sensor b are arranged at positions separated by a predetermined distance PA in the axial direction.

  The heat insulation pipe 2 is a cylindrical inspection object to be inspected by the pulse magnetic inspection apparatus 1 according to the present embodiment, and has a steel pipe 2a having a thickness of 7.2 mm inside the heat insulation pipe 2. The periphery of the steel pipe 2a is covered with a heat insulating material 2b having a thickness of 50 mm, and the periphery of the heat insulating material 2b is covered with a molten zinc iron plate having a thickness of 0.3 mm as an outer cylinder 2c. The numerical value is an example.

  The movable inspection unit 12 inserts the heat insulation pipe 2 and applies a pulsed magnetic field via the exciting coils 3-1 and 3-2, and changes the magnetic field transmitted through the heat insulation pipe 2 with a magnetic sensor a composed of a magnetoresistive element. , B. Here, as magnetic sensors a and b, in addition to magnetoresistive elements (MR elements), magnetic signals from extremely low frequencies such as magneto-impedance elements, Hall elements, flux gates, superconducting quantum interference elements (SQUIDs) are measured. You can use a magnetic sensor that can.

  The magnetic sensor circuit 7 is a circuit for driving the magnetic sensors a and b and measuring a magnetic field. The magnetic sensors a and b are mounted, and the magnetic sensor circuit 7 is electrically connected to the magnetic sensors a and b through flexible wiring boards provided in the magnetic sensor units 4a and 4b.

  The pulse power supply 8 can apply a pulse voltage to at least one of the pair of exciting coils 3-1 and 3-2. The pulse power supply 8 can output a square wave and can be driven at a predetermined repetition rate and duty ratio. The pulse power supply 8 is electrically connected to the power supply switching circuit 9.

  The power supply switching circuit 9 can switch the current direction of one excitation coil and the other excitation coil of the pair of excitation coils to the same direction or the opposite direction, or to switch only one of the pair of excitation coils. Circuit. The power source switching circuit 9 can select the direction of the current flowing through the pair of exciting coils 3-1 and 3-2 and operating both or only one of them. Here, if the current directions of both exciting coils 3-1 and 3-2 are operated in the same manner, a pulse magnetic field in the same direction can be applied to the heat insulating pipe 2.

The computer 10 detects a pulse magnetic field generated when at least one of the pair of exciting coils 3-1 and 3-2 is driven by the pulse power supply 8 by the magnetic sensors a and b, and detects the magnetic sensors a and b. It functions as an analysis means for analyzing the response of the pulsed magnetic field.
The detection signal waveform data input to the computer 10 may be input to another computer 11 by wireless communication or movement of a data recording medium, and the pulse magnetic field response analysis may be performed by the computer 11. That is, the analysis means can be configured in the computer 11, and it is not always necessary to mount the analysis means on the movable inspection unit 12.
The computer 10 also functions as a control unit that controls the moving speed of the movable inspection unit 12, the voltage applied to the excitation coils 3-1, 3-2, and the magnetic sensors a, b.

The method of inspecting the heat insulating pipe 2 using the pulse magnetic inspection apparatus 1 is based on the method described in Patent Document 1.
That is, the inspection method applied to the pulse magnetic inspection apparatus 1 is a method for nondestructive inspection of defects in the heat insulating pipe 2, and the heat insulating pipe 2 is inserted into the pair of exciting coils 3-1, 3-2 to thereby supply a pulse power source. 8, driving the pair of exciting coils 3-1 and 3-2 to apply a pulse magnetic field to the heat insulating pipe 2, and the heat insulating pipe 2 generated by the pair of exciting coils 3-1 and 3-2. Detecting a magnetic field parallel to the central axis direction of the magnetic sensors by the magnetic sensors a and b, and identifying a defect in the heat insulating pipe 2 by analyzing the pulse intensity and signal time attenuation in the output signals of the magnetic sensors a and b, Execute.

Furthermore, in this embodiment, the following method is implemented by the pulse magnetic inspection apparatus 1.
When performing the step of applying the pulsed magnetic field and the step of detecting the magnetic field by the magnetic sensors a and b, the movable inspection unit 12 is moved in the axial direction.
The control means configured in the computer 10 includes the period of the voltage applied to the excitation coils 3-1 and 3-2, which is the source of the pulse magnetic field, and the time required for the movable inspection unit 12 to move by a predetermined distance PA. Control to be equal to each other. Alternatively, the control is performed so that the integral multiple of 2 or more of the period of the voltage applied to the exciting coils 3-1 and 3-2 and the time required for the movable inspection unit 12 to move by the predetermined distance PA are equal.
Thereby, the magnetic sensor a and the magnetic sensor b can be sequentially arranged at the same position on the heat insulating pipe 2 to detect the magnetic field in synchronization with the input of the pulse magnetic field. The reliability of the inspection can be improved by analyzing based on a plurality of detection signals for the same location obtained in this way.
The detection of the magnetic field by the magnetic sensor a and the detection of the magnetic field by the magnetic sensor b at the same location are not simultaneously but before or after the time required for the movable inspection unit 12 to move by the predetermined distance PA.
On the other hand, the magnetic noise acts simultaneously on the magnetic sensor a and the magnetic sensor b. Further, the magnetic sensors a01, a02,... And the magnetic sensors b01, b02,.
If there is no noise, the detection signal waveform by the magnetic sensor a and the detection signal waveform by the magnetic sensor b are similar (including a similarity ratio of 1: 1) with the same location as the measurement point, so that noise can be detected. it can.
Therefore, by comparing the detection signal from the magnetic sensor a with the detection signal from the magnetic sensor b using the same location as a measurement point, noise can be detected and the reliability of the inspection can be improved.

  The movable inspection unit 12 may be stopped at the time of detection by the magnetic sensor, or may be detected by the magnetic sensor while moving. In the former case, the “time required to move by a predetermined distance PA” to be synchronized with the input of the pulse magnetic field includes a stop time for detection by the magnetic sensor.

  When priority is given to the detection accuracy of the magnetic field, it can be dealt with by reducing the moving speed of the movable inspection unit 12 by decreasing the predetermined distance PA. When priority is given to inspection efficiency, the movable inspection unit is increased by increasing the predetermined distance PA. This can be accommodated by increasing the moving speed of 12, and can be configured according to the purpose and application.

The configuration of the magnetic sensor unit that can be further added will be described.
For the magnetic sensor units 4a and 4b, the magnetic sensor units can be additionally installed with the predetermined distance PA as the arrangement pitch. In other words, the magnetic sensor units 4a, 4b, 4c,... (Not shown) are added with the predetermined distance PA as the arrangement pitch. As a result, the signal waveform to be compared for noise detection increases to 3 or more, and the inspection reliability can be further improved.
Further, one or more magnetic sensor units 104a, 204a, 304a,... (Not shown) are arranged in a section between the plurality of magnetic sensor units 4a, 4b arranged at a position separated by a predetermined distance PA. .., And another magnetic sensor unit 104b is separated from the magnetic sensor units 204a, 304a,... In the axial direction by the same predetermined distance PA in the axial direction. A configuration in which other magnetic sensor units 204b, 304b,. Then, the signals detected by the magnetic sensor units 4a, 4b, 4c,..., And the second set of signals detected by the plurality of magnetic sensors arranged at positions separated by the predetermined distance PA are detected. The signals detected by the magnetic sensor units 104a, 104b, 104c,..., The third set is detected by the magnetic sensor units 204a, 204b, 204c,. Analyzing can improve the reliability of the inspection and improve the axial resolution.

  In addition, the similarity ratio described above is “a similar shape between the detection signal waveform of the magnetic sensor a and the detection signal waveform of the magnetic sensor b with the same location as the measurement point if there is no noise”. It depends on the distance from the axial center of the exciting coils 3-1 and 3-2. This is because the signal intensity decreases with the peak at the same center and away from the same center. This distance may vary depending on the magnetic sensor unit. In that case, the analyzing means corrects and normalizes the signal according to the distance, and then compares the signals. In the case of only the magnetic sensors a and b having the same distance from the same center as shown in FIG. 1, there is no need for correction due to the difference in sensor arrangement. That is, in this case, the similarity ratio is 1: 1.

In the above embodiment, since a plurality of magnetic sensors are arranged in the circumferential direction, the inspection result can be generated as mapping data having the coordinate in the axial direction and the coordinate in the circumferential direction of the pipe to be inspected. it can.
In the case where no circumferential coordinate is required, one magnetic sensor may be provided for each magnetic sensor unit. For example, the present invention can be applied effectively when there is a possibility that a defect may occur only at a specific position (for example, apex position) in the circumferential direction of the pipe to be inspected. Further, mapping data can be generated by repeatedly scanning in the axial direction while shifting the position of the magnetic sensor in the circumferential direction.

[Second Embodiment]
Next, a second embodiment will be described. Except as described below, the present embodiment has the same configuration as that of the first embodiment.
As shown in FIG. 2A, magnetic sensors a01, a02a03,... Are arranged on the magnetic sensor unit 4a. FIG. 2B shows a schematic diagram illustrating this in a plan view.
As shown in FIG. 2B, the magnetic sensors a01, a03, a05,... Constitute a circumferential row, and the magnetic sensors a02, a04, a06,. Configure. Two or more circumferential rows of the magnetic sensor are formed. The circumferential arrangement pitch PB is constant regardless of the row.
In the case of two rows, as shown in FIG. 2 (b), the row composed of magnetic sensors a02, a04, a06,... Is different from the row composed of magnetic sensors a01, a03, a05,. The installation position is offset in the circumferential direction by a half of the arrangement pitch PB.
In the case of three rows, as shown in FIG. 2 (c), the row of magnetic sensors a02, a05, a08,... Is different from the row of magnetic sensors a01, a04, a07,. The installation positions are offset in the circumferential direction by one third of the arrangement pitch PB, and the magnetic sensors a03, a06, a09,. The arrangement positions of the rows constituted by are offset in the circumferential direction by one third of the arrangement pitch PB.
Similarly, if there are four columns, one-fourth of the arrangement pitch PB is sequentially offset between adjacent columns, and if five columns, one-fifth of the arrangement pitch PB is sequentially offset between adjacent columns.・ Offset so.

Elements indicated by circles in FIG. 2B are virtual magnetic sensors c01, c02, c03,. Although the virtual magnetic sensor c01 is not actually provided with a magnetic sensor, the virtual magnetic sensor c01 can interpolate based on detection signals from the surrounding magnetic sensors a01, a02, and a03 to obtain a detection signal from the virtual magnetic sensor c01. The same applies to the virtual magnetic sensors c02, c03, c04,... Shown in FIG. 2B and the virtual magnetic sensors c01, c02, c03,.
Accordingly, the spatial resolution can be improved more than the arrangement pitch of the actually arranged magnetic sensors.
The above is a case where a magnetic field is simultaneously detected by the magnetic sensor on the magnetic sensor unit 4a.
When the method of detecting the same position with a time difference as in the first embodiment is also implemented, a magnetic sensor having a plurality of circumferential rows as in the magnetic sensor unit 4a as shown in FIG. The unit 4b is arranged in the axial direction, and detection is performed with a time difference between the magnetic sensor unit 4a and the magnetic sensor unit 4b at the same position with respect to the heat insulating pipe 2.

  Furthermore, as shown in FIGS. 4 and 5, it is also possible to implement a configuration in which the gap between the magnetic sensors is widened. 4 shows a modification in which the gap between the magnetic sensors is widened with respect to the form shown in FIGS. 2A and 2B, and FIG. 5 shows the gap between the magnetic sensors in the form shown in FIG. The deformation | transformation form expanded and arranged is shown. 4 shows a form in which there is no overlapping portion in the circumferential direction between the row of magnetic sensors a01, a03,... And the row of magnetic sensors a02, a04,. The case where there are overlapping parts in the circumferential direction is shown. In either case, as shown in FIGS. 4B and 5B, detection signals from the virtual magnetic sensors c01, c02, c03,... Can be calculated, and the spatial resolution can be improved.

[Third Embodiment]
Next, a third embodiment will be described. Except as described below, the present embodiment has the same configuration as that of the first embodiment.
In the present embodiment, as shown in FIG. 6, as magnetic sensors arranged on the magnetic sensor unit 4a, magnetic sensors a01, a02,... For detecting a magnetic field in a direction parallel to the central axis of the pipe to be inspected. In addition, magnetic sensors a01m, a02m,... That detect a magnetic field in a direction having a twist angle (90 degrees in the drawing) with respect to the central axis are included. The detection axes of the magnetic sensors a01m, a02m,... Are arranged to be twisted with respect to the central axis of the pipe to be inspected, and the twist angle is preferably 90 degrees as shown. The “direction parallel to the central axis of the pipe to be inspected” has the same meaning as the “axial direction” already used. Arrow A indicates the axial direction.
In the configuration shown in FIG. 6A, magnetic sensors having different detection directions such as a magnetic sensor a01, a magnetic sensor a01m, a magnetic sensor a02, a magnetic sensor a02m,... Are alternately arranged along the circumferential direction. Is done.
In the configuration shown in FIG. 6B, the circumferential rows of the magnetic sensors a01, a02,... And the circumferential rows of the magnetic sensors a01m, a02m,. Arranged at different positions.

As another example of the present embodiment, as shown in FIG. 7, magnetic sensors a01, a02, which detect magnetic fields in directions parallel to the central axis of the pipe to be inspected, as magnetic sensors arranged on the magnetic sensor unit 4a. .. In addition to magnetic sensors a01n, a02n,... That detect a magnetic field in a direction parallel to a straight line that intersects the central axis (at 90 degrees in the drawing). It is preferable that a straight line obtained by extending the detection axes of the magnetic sensors a01n, a02n,... Intersects the central axis of the pipe to be inspected, and the crossing angle is 90 degrees as shown.
In the configuration shown in FIGS. 7A1 and 7A2, magnetic sensors having different detection directions such as a magnetic sensor a01, a magnetic sensor a01n, a magnetic sensor a02, a magnetic sensor a02n,. Alternatingly arranged.
In the configuration shown in FIGS. 7 (b1) and (b2), there are circumferential rows of magnetic sensors a01, a02,... And circumferential rows of magnetic sensors a01n, a02n,. Arranged at different positions in the axial direction.

  Further, in addition to the magnetic sensors a01, a02,... Detecting the magnetic field in the direction parallel to the central axis of the pipe to be inspected, the magnetic sensors a01m, a02m, detecting the magnetic field in the direction having a twist angle with respect to the central axis. .. And a configuration including magnetic sensors a01n, a02n,... For detecting a magnetic field in a direction parallel to a straight line intersecting the central axis.

  One or a plurality of such magnetic sensor units 4a are arranged in the axial direction. Note that it is arbitrary to increase the total number of columns by increasing the number of columns on one magnetic sensor unit, or to increase the total number of columns by increasing the number of magnetic sensor units. By increasing the number of columns, the first embodiment and the second embodiment can be implemented simultaneously.

A signal caused by a defect in the steel pipe 2a that is the pipe to be inspected can be detected by magnetic sensors a01, a02,... That mainly detect a magnetic field in a direction parallel to the central axis of the pipe to be inspected. Since the disturbance magnetic field is not limited to this direction, it can also be detected by the magnetic sensors a01m, a02m,... Or the magnetic sensors a01n, a02n,. The disturbance magnetic field may be affected by external noise, abnormalities of the outer cylinder 2c, joints, and the like.
The detection signals of the magnetic sensors a01, a02,..., The magnetic sensors a01m, a02m,. .., The detection signals of the magnetic sensors a01m, a02m,... And the detection signals of the magnetic sensors a01n, a02n,.
Therefore, by analyzing the detection signals of these magnetic sensors by the analyzing means, it is possible to discriminate the signal caused by the defect of the steel pipe 2a that is the pipe to be inspected from the disturbance magnetic field and improve the reliability of the inspection.
6 and FIG. 7, the arrangement density of the magnetic sensors a01m, a02m,... And the magnetic sensors a01n, a02n,. Equal to the density. However, among the magnetic sensors a01, a02,..., The magnetic sensors a01m, a02m,... And the magnetic sensors a01n, a02n,. If the signal due to the magnetic field can be detected sufficiently, the magnetic sensor that detects the magnetic field in the other direction should be thinned out appropriately and placed at a lower density than the magnetic sensor that detects the magnetic field in the specific direction. It is also possible to implement.

[Fourth Embodiment]
Next, a fourth embodiment will be described. Except as described below, the present embodiment has the same configuration as that of the first embodiment.
In this embodiment, as shown in FIG. 8, the magnetic sensor units 4a and 4b are movably supported so that the predetermined distance PA can be changed.
The movable inspection unit 12 is provided with a linear actuator 13, and the magnetic sensor units 4 a and 4 b are movably supported on the movable inspection unit 12 by the linear actuator 13. The linear actuator 13 operates based on a control command from the computer 10, and the computer 10 controls the positions of the magnetic sensor units 4a and 4b.
Thus, the magnetic sensors a and b can be arranged at arbitrary positions with respect to the exciting coils 3-1 and 3-2 to detect the magnetic field. For example, the distance between the magnetic sensor a and the magnetic sensor b can be changed, the predetermined distance PA in the first embodiment can be changed, or the spatial resolution in the second embodiment can be changed.
Depending on the purpose, the linear actuator 13 may be one-to-one so that the individual magnetic sensor units 4a and 4b are moved independently, or the axial center between the exciting coils 3-1 and 3-2. It is possible to implement one that is symmetrically interlocked with the center, one in which the linear actuator 13 is provided in only one of the magnetic sensor units 4a and 4b, and the like.

Such a change can also be achieved by using a magnetic field for detecting a defect selected by the control means from magnetic sensors arranged in the axial direction as shown in FIG. However, the configuration shown in FIG. 8 depends on the axial position control resolution, whereas the configuration shown in FIG. 9 depends on the axial arrangement pitch.
As a magnetic sensor to be used in FIG. 9, a sensor mounted on the magnetic sensor units 4a, 4b, 4c, 4d, 4e, 4f is selected, a sensor mounted on the magnetic sensor units 4a, 4c, 4e is selected, In addition, select the one mounted on the magnetic sensor units 4b, 4d, 4f as another set), select the one mounted on the magnetic sensor units 4c, 4d, or select the one mounted on the magnetic sensor units 4b, 4e. For example, the predetermined distance PA in the first embodiment can be changed, or the spatial resolution in the second embodiment can be changed.

1 Nondestructive inspection equipment (pulse magnetic inspection equipment)
DESCRIPTION OF SYMBOLS 2 Heat insulation piping 2a Steel pipe 2b Heat insulation material 2c Outer cylinder 3-1 Excitation coil 3-2 Excitation coil 4a, 4b, 4c, ... Magnetic sensor unit 5 Self-propelled moving body 6 Driving drive circuit 7 Magnetic sensor circuit 8 Pulse power supply 9 Power supply switching circuit 10 Computer 11 Computer 12 Movable inspection unit 13 Linear actuators a01, a02, ... Magnetic sensors a01m, a02m, ... Magnetic sensors a01n, a02n, ... Magnetic sensors b01, b02, ...・ Magnetic sensor

Claims (9)

A non-destructive inspection device using magnetism for non-destructive inspection of defects in piping to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils that are separated from each other in the axial direction, and a plurality of magnetic sensors are arranged at least at a predetermined distance in the axial direction. Consists of
The control means controls the non-destructive inspection so that a period of the voltage or an integral multiple of 2 or more thereof is equal to a time required for the movable inspection unit to move by the predetermined distance. apparatus.   One or two or more magnetic sensors are arranged in a section between a plurality of magnetic sensors arranged at positions separated by the predetermined distance, and the same predetermined distance in the axial direction from the magnetic sensor arranged in the section between the magnetic sensors. The nondestructive inspection apparatus according to claim 1, wherein another magnetic sensor is disposed at a position spaced apart from each other. Comprising an analyzing means for analyzing a signal detected by the magnetic sensor;
The analysis means uses the same position as a measurement point based on a set of signals detected by a plurality of magnetic sensors arranged at different positions arranged at different timings at a certain position on the pipe to be inspected. The nondestructive inspection apparatus according to claim 1, wherein a signal resulting from the defect is analyzed.   The non-destructive inspection apparatus according to claim 3, wherein the analysis unit detects the noise based on the assumption that the waveforms of the signals included in the set are similar if there is no noise. . A non-destructive inspection device using magnetism for non-destructive inspection of defects in piping to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
The magnetic sensor comprises a plurality of circumferential rows arranged in the circumferential direction of the pipe to be inspected between the excitation coils separated from each other in the axial direction, and the circumferential rows are arranged in the circumferential direction. A non-destructive inspection apparatus comprising two or more rows, wherein each magnetic sensor belonging to the row is offset in the circumferential direction with respect to a magnetic sensor belonging to another adjacent row. A non-destructive inspection device using magnetism for non-destructive inspection of defects in piping to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
The magnetic sensor is composed of a plurality arranged in the circumferential direction and / or the axial direction of the pipe to be inspected between the exciting coils separated from each other in the axial direction.
The plurality of magnetic sensors include a magnetic sensor that detects a magnetic field in a direction parallel to a central axis of the pipe to be inspected, a magnetic sensor that detects a magnetic field in a direction having a twist angle with respect to the central axis, and / or the center. A non-destructive inspection apparatus characterized by including a magnetic sensor for detecting a magnetic field in a direction parallel to a straight line intersecting with an axis.   A magnetic sensor for detecting a magnetic field in a direction parallel to the central axis of the pipe to be inspected, a magnetic sensor for detecting a magnetic field in a direction having a twist angle with respect to the central axis, and / or a direction parallel to a straight line intersecting the central axis The nondestructive inspection apparatus according to claim 6, wherein magnetic sensors for detecting the magnetic field are alternately arranged in the circumferential direction or the axial direction. A non-destructive inspection device using magnetism for non-destructive inspection of defects in piping to be inspected,
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils that are separated from each other in the axial direction, and a plurality of magnetic sensors are arranged at least at a predetermined distance in the axial direction. A non-destructive inspection apparatus characterized in that the predetermined distance is movably supported. A non-destructive inspection device using magnetism for non-destructive inspection of defects in piping
A movable inspection unit that is equipped with an excitation coil and a magnetic sensor and is arranged outside the inspection pipe and moves in the axial direction of the inspection pipe;
A moving speed of the movable inspection unit, a voltage applied to the excitation coil and a control means for controlling the magnetic sensor,
The exciting coil is constituted by a pair in which the pipe to be inspected is inserted and arranged apart from each other in the axial direction,
One or a plurality of the magnetic sensors are arranged in the circumferential direction of the pipe to be inspected between the excitation coils separated from each other in the axial direction, and arranged at least in the axial direction,
The non-destructive inspection apparatus, wherein the control means is selected from magnetic sensors arranged in the axial direction and used to detect a magnetic field for detecting the defect.

Images