JP2020012851A - Non-destructive inspection method - Google Patents

Abstract

To provide a non-destructive inspection device which enables easy analysis of an inspection target.SOLUTION: A non-destructive inspection device 100 disclosed herein comprises: three-axis magnetic sensors 11 and 12 for detecting three-axial magnetic components that are orthogonal to each other; and a signal analyzer 2 configured to combine the three-axial magnetic components detected by the three-axis magnetic sensors 11 and 12 into a single waveform to acquire magnetic information within inspection target concrete 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nondestructive inspection method.

  Conventionally, a non-destructive inspection method is known (for example, see Patent Document 1).

  Patent Literature 1 discloses a nondestructive inspection device including an excitation coil that magnetizes a reinforcing bar in concrete and a pickup coil that detects magnetism of the magnetized reinforcing bar. Further, the pickup coil constitutes a magnetic sensor for detecting magnetism in one axis direction.

JP 2005-292111 A

  However, in Patent Literature 1, since the rebar is magnetized and the magnetism of the magnetized rebar is detected, it is necessary to know the position of the rebar for magnetizing in advance. In addition, since a magnetic sensor that detects magnetism in one axial direction is used, the detected waveform (peak position) differs depending on the axial direction detected by the magnetic sensor with respect to the rebar. As a result, when the position of the reinforcing bar is not grasped in advance, there is a problem that it is difficult to analyze the inspection object easily because the skill is required to analyze the waveform.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a nondestructive inspection method capable of easily analyzing an inspection object. is there.

  In order to achieve the above object, a nondestructive inspection method according to one aspect of the present invention is characterized in that positions in the first direction are mutually different in a second direction intersecting a magnetic body extending in the first direction within the inspection object. A step of detecting three-axis magnetic components orthogonal to each other in each of the plurality of paths while moving on a plurality of paths on different inspection objects; and for each of the plurality of paths, detecting the detected three-axis magnetic components. Acquiring one synthesized waveform as magnetic information in the inspection object.

  In the nondestructive inspection method according to the above aspect, the step of detecting the three-axis magnetic component preferably includes the step of detecting the three-axis magnetic component by the three-axis magnetic sensor for inspection and the three-axis magnetic sensor for compensation. The step of acquiring the magnetic information in the inspection object includes the step of acquiring the magnetic information in the inspection object based on the detection results of the three-axis magnetic sensor for inspection and the three-axis magnetic sensor for compensation. With this configuration, it is possible to reduce the influence of geomagnetism and magnetic substances around the inspection object based on the detection results of the three-axis magnetic sensor for inspection and the three-axis magnetic sensor for compensation. The magnetism in the object can be accurately measured.

  In this case, preferably, the step of acquiring the magnetic information in the inspection object includes the step of synthesizing the three-axis magnetic components detected by the three-axis magnetic sensor for inspection into one waveform to obtain the result of the three-axis magnetic compensation. The method includes a step of combining magnetic components of the three axes detected by the sensor and compensating for the result of forming one waveform to obtain magnetic information in the inspection object. With this configuration, the detection result of the compensation triaxial magnetic sensor is subtracted from the detection result of the inspection triaxial magnetic sensor, thereby reducing noise due to geomagnetism and the influence of magnetic substances around the inspection target. can do. Thereby, inspection accuracy can be improved.

  In the non-destructive inspection method according to the one aspect, preferably, the step of acquiring magnetic information in the inspection target includes, in a state where a geomagnetic component is reduced from a detection result of the triaxial magnetic component, a triaxial magnetic component. The method includes a step of acquiring one synthesized waveform as magnetic information in the inspection object. With this configuration, the triaxial magnetic components detected in a state where the geomagnetic components are reduced are combined, so that the analysis of the magnetic body in the inspection object can be performed with high accuracy.

  In the nondestructive inspection method according to the one aspect, preferably, the step of acquiring magnetic information in the inspection target includes the step of acquiring magnetic information of a reinforcing bar in concrete. With this configuration, corrosion or breakage of the reinforcing steel in the concrete can be easily inspected.

  According to the present invention, the analysis of the inspection object can be easily performed as described above.

It is a block diagram showing the whole nondestructive inspection device composition by one embodiment of the present invention. FIG. 4 is a diagram for explaining signal processing of the nondestructive inspection device according to one embodiment of the present invention. It is a figure showing an example of an inspection route of a nondestructive inspection device by one embodiment of the present invention. It is a figure showing an example of a magnetic waveform of a nondestructive inspection device by one embodiment of the present invention.

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

(Configuration of non-destructive inspection equipment)
With reference to FIG. 1, an overall configuration of a nondestructive inspection apparatus 100 according to an embodiment of the present invention will be described.

  As shown in FIG. 1, the nondestructive inspection device 100 is configured to inspect corrosion, breakage, and the like of a reinforcing bar 5 in concrete 4. That is, the non-destructive inspection device 100 is configured to inspect the state of the internal reinforcing bar 5 without breaking the concrete 4. The non-destructive inspection device 100 includes a self-propelled robot 1, a signal analysis device 2, and a robot control device 3. The self-propelled robot 1 includes three-axis magnetic sensors 11 and 12, and amplifiers 13 and 14. Note that the signal analyzer 2 is an example of the “control unit” of the present invention. Further, the three-axis magnetic sensors 11 and 12 are examples of the “three-axis magnetic sensor for inspection” and the “three-axis magnetic sensor for compensation” of the present invention, respectively.

  The self-propelled robot 1 is configured to detect magnetism in the concrete 4 while moving on the surface 4a of the concrete 4. Specifically, the self-propelled robot 1 detects magnetism by the three-axis magnetic sensors 11 and 12 at each point while moving along a predetermined inspection route.

  The three-axis magnetic sensors 11 and 12 are configured to detect three-axis (x-axis, y-axis, and z-axis) magnetic components orthogonal to each other. The three-axis magnetic sensor 11 is arranged on the inspection target (concrete 4) side of the self-propelled robot 1. The triaxial magnetic sensor 11 mainly detects the magnetism of the reinforcing bar 5 in the concrete 4. The signals of the x-axis, y-axis, and z-axis magnetic information detected by the three-axis magnetic sensor 11 are amplified by the amplifier 13 and transmitted to the signal analyzer 2.

  The triaxial magnetic sensor 12 is disposed on the opposite side of the triaxial magnetic sensor 11 from the object to be inspected (the concrete 4). That is, the three-axis magnetic sensor 12 is arranged at a position farther from the inspection target than the three-axis magnetic sensor 11. The signals of the x-axis, y-axis, and z-axis magnetic information detected by the three-axis magnetic sensor 12 are amplified by the amplifier 14 and transmitted to the signal analyzer 2. Each of the triaxial magnetic sensors 11 and 12 includes a magnetic sensor of a flux gate type. The x-axis, y-axis, and z-axis of the three-axis magnetic sensors 11 and 12 are arranged so as to be substantially in the same direction.

  Here, in the present embodiment, the signal analyzer 2 synthesizes the three-axis (x-axis, y-axis, and z-axis) magnetic components detected by the three-axis magnetic sensors 11 and 12 into one waveform to be inspected. Is configured to acquire magnetic information in the concrete 4. Specifically, the signal analyzer 2 is configured to acquire magnetic information in the concrete 4 based on the detection results of the three-axis magnetic sensors 11 and 12.

  Further, the signal analyzer 2 combines the triaxial magnetic components into one waveform in a state where the geomagnetic components are reduced from the detection results of the triaxial magnetic sensors 11 and 12, and generates a single waveform. It is configured to obtain information. As for the magnetism of the terrestrial magnetism component, the terrestrial magnetism component is reduced from the detection result of the magnetism to be inspected using a band pass filter (BPF).

  In addition, the signal analysis device 2 combines the three-axis magnetic components detected by the three-axis magnetic sensor 11 into one waveform, and combines the three-axis magnetic components detected by the three-axis magnetic sensor 12 with the result. The magnetic information in the concrete 4 to be inspected is obtained by compensating for the result of one waveform.

  The robot control device 3 is configured to control the movement of the self-propelled robot 1. Specifically, the robot control device 3 is configured to move the self-propelled robot 1 along an inspection route based on a program.

(Explanation of signal processing)
The signal analysis of the magnetism detected by the three-axis magnetic sensors 11 and 12 will be described with reference to FIG.

  The magnetic signal Hxa in the x-axis direction detected by the three-axis magnetic sensor 11 has a geomagnetic component reduced by a BPF (Band Pass Filter) and becomes a magnetic signal Hx1. The magnetic signal Hya in the y-axis direction detected by the three-axis magnetic sensor 11 is reduced in geomagnetic component by the BPF to become a magnetic signal Hy1. The magnetic signal Hza in the z-axis direction detected by the three-axis magnetic sensor 11 is reduced in geomagnetic component by the BPF to become a magnetic signal Hz1.

  The magnetic signal Hxb in the x-axis direction detected by the three-axis magnetic sensor 12 has a geomagnetic component reduced by the BPF and becomes a magnetic signal Hx2. The magnetic signal Hyb in the y-axis direction detected by the three-axis magnetic sensor 12 is reduced in geomagnetic component by the BPF to become a magnetic signal Hy2. The magnetic signal Hzb in the z-axis direction detected by the three-axis magnetic sensor 12 is reduced in geomagnetic component by the BPF to become a magnetic signal Hz2.

The magnetic signals Hx1, Hy1, and Hz1 based on the detection result of the three-axis magnetic sensor 11 are combined by the equation (1) to become the magnetic signal H1. Further, the magnetic signals Hx2, Hy2, and Hz2 based on the detection result of the three-axis magnetic sensor 12 are combined into the magnetic signal H2 by Expression (2).

  In this case, the magnetic signal H1 includes a signal of the reinforcing bar 5 and noise. Further, the magnetic signal H2 includes a signal of the reinforcing bar 5 and noise. The noise is caused by a magnetic body or the like existing around the inspection object. For example, the noise is caused by a car traveling around the inspection object.

The obtained magnetic signal H1 and magnetic signal H2 are compensated as in equation (3). Thus, the magnetic signal H has reduced noise. That is, since the rebar 5 is located at a short distance from the triaxial magnetic sensors 11 and 12, signals of different levels are detected by the triaxial magnetic sensors 11 and 12. On the other hand, since the magnetic material that causes noise is far from the three-axis magnetic sensors 11 and 12, signals of substantially the same level are detected by the three-axis magnetic sensors 11 and 12. Therefore, noise is reduced by subtracting the magnetic signal H2 from the magnetic signal H1.

  The data of the obtained magnetic signal H is collected along the inspection location. That is, the distribution of the magnetic information detected along the inspection route is recorded for each location. For example, as shown in FIG. 3, the self-propelled robot 1 is moved along the inspection route. The magnetic signal H is recorded along Lines 1-4. In this case, as shown in FIG. 4, peaks of A, B, C, and D appear for Lines 1 to 4, respectively. Since the magnetic signal H is composed of three-axis magnetic components, a peak is detected at a position near the reinforcing bar 5. Peaks A of Lines 1 to 4 are signals based on the reinforcing bar 5a. Peaks B of Lines 1 to 4 are signals based on the reinforcing bar 5b. Peaks C of Lines 1 to 4 are signals based on the reinforcing bar 5c. Peaks D of Lines 1 to 4 are signals based on the reinforcing bar 5d.

  Here, the peak C of Line 3 is smaller than the peak C of Line 2 and the peak C of Line 4. That is, the peak C of Line 3 is smaller than the peaks C before and after. In this case, it is possible to easily determine that there is an abnormality such as breakage or corrosion at the peak C of Line 3 even by a non-expert.

(Effects of the embodiment)
In the present embodiment, the following effects can be obtained.

  In the present embodiment, as described above, the signal analyzer that combines the three-axis magnetic components detected by the three-axis magnetic sensors 11 and 12 into one waveform to acquire the magnetic information in the concrete 4 to be inspected. 2 is provided. As a result, the peak of the combined waveform of the three-axis magnetic components appears at the position closest to the reinforcing bar 5 in the concrete 4. Even if the position of the reinforcing bar 5 is not known in advance, the peak of the combined waveform is analyzed. By doing so, the analysis of the reinforcing bar 5 in the concrete 4 to be inspected can be easily performed. In addition, since it is not necessary to magnetize the reinforcing bar 5 in the concrete 4, it is possible to suppress an increase in the detection time for magnetizing the reinforcing bar 5.

  In the present embodiment, as described above, the signal analyzer 2 is configured to acquire the magnetic information in the concrete 4 based on the detection results of the three-axis magnetic sensor 11 and the three-axis magnetic sensor 12. Thus, the influence of the geomagnetism and the magnetic material around the concrete 4 to be inspected can be reduced based on the detection results of the three-axis magnetic sensors 11 and 12, so that the magnetism in the concrete 4 to be inspected can be reduced. It can be measured accurately.

  Further, in the present embodiment, as described above, the signal analysis device 2 combines the three-axis magnetic components detected by the three-axis magnetic sensor 11 to form a single waveform, and the three-axis magnetic sensor 12 detects the result. The three-axis magnetic components thus synthesized are combined into a single waveform, compensated by the result, and magnetic information in the concrete 4 to be inspected is acquired. Thus, by subtracting the detection result of the three-axis magnetic sensor 12 from the detection result of the three-axis magnetic sensor 11, it is possible to reduce the noise due to the influence of geomagnetism or a magnetic material around the inspection object. Thereby, inspection accuracy can be improved.

  In the present embodiment, as described above, the three-axis magnetic sensor 12 is arranged on the opposite side of the three-axis magnetic sensor 11 from the inspection object. Thereby, the magnetism in the concrete 4 to be inspected is detected at a strong level by the three-axis magnetic sensor 11, and the magnetism such as the terrestrial magnetism and the magnetic material around the concrete 4 to be inspected is detected by the three-axis magnetic sensors 11 and 12. Since detection can be performed at substantially the same level in both, the detection result of the three-axis magnetic sensor 12 is subtracted from the detection result of the three-axis magnetic sensor 11 to obtain geomagnetism and magnetic materials around the concrete 4 to be inspected. Can be easily reduced.

  Further, in the present embodiment, as described above, the signal analyzer 2 combines the three-axis magnetic components into one waveform while reducing the geomagnetic component from the detection results of the three-axis magnetic sensors 11 and 12. Then, magnetic information in the concrete 4 to be inspected is acquired. Thereby, the triaxial magnetic components detected in a state where the geomagnetic components are reduced are synthesized, so that the analysis of the reinforcing bar 5 in the concrete 4 to be inspected can be performed with high accuracy.

(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 embodiment, an example in which reinforced concrete is used as the inspection object has been described, but the present invention is not limited to this. In the present invention, other than reinforced concrete may be used as the inspection object.

  Further, in the above embodiment, an example of the nondestructive inspection device including two three-axis magnetic sensors has been described, but the present invention is not limited to this. The nondestructive inspection apparatus of the present invention may be provided with one three-axis magnetic sensor, or may be provided with three or more three-axis magnetic sensors.

  Further, in the above-described embodiment, an example of the configuration in which the three-axis magnetic sensor is moved by the self-propelled robot and the magnetism of each portion is measured has been described, but the present invention is not limited to this. In the present invention, the magnetism of each location may be measured by manually moving the three-axis magnetic sensor by the user, or the magnetism of each location may be measured by moving the inspection object with respect to the three-axis magnetic sensor. Is also good.

  Further, in the above-described embodiment, an example is shown in which the three-axis magnetic sensor for inspection and the three-axis direction to be measured by the three-axis magnetic sensor for compensation are arranged so that the directions are substantially the same as each other. The present invention is not limited to this. In the present invention, the three-axis magnetic sensor for inspection and the three-axis magnetic sensor for compensation may be arranged so that the directions of the three axes to be measured are different from each other.

  Further, in the above embodiment, the example in which the geomagnetic component is reduced using the band-pass filter has been described, but the present invention is not limited to this. In the present invention, the terrestrial magnetic component may be reduced using a device other than the band-pass filter. For example, the terrestrial magnetic component may be reduced by a filtering process other than a bandpass filter or a DC cut.

  Further, in the above-described embodiment, the example in which the three-axis magnetic sensor includes the flux gate type magnetic sensor has been described, but the present invention is not limited to this. In the present invention, the three-axis magnetic sensor may be constituted by a magnetic sensor other than the flux gate type.

2 signal analyzer (control unit)
4 concrete (object to be inspected)
5, 5a, 5b, 5c, 5d Rebar 11 Triaxial magnetic sensor (triaxial magnetic sensor for inspection)
12 Three-axis magnetic sensor (compensation three-axis magnetic sensor)
100 non-destructive inspection equipment

Claims (5)

While moving on a plurality of paths on the inspection object having different positions in the first direction in a second direction intersecting a magnetic body extending in the first direction within the inspection object, the plurality of paths are moved. Detecting a magnetic component of three axes orthogonal to each other in each of:
Acquiring a single waveform obtained by combining the detected three-axis magnetic components for each of the plurality of paths as magnetic information in the inspection object. The step of detecting the three-axis magnetic component includes a step of detecting a three-axis magnetic component by a three-axis magnetic sensor for inspection and a three-axis magnetic sensor for compensation,
The step of acquiring magnetic information in the inspection object includes a step of acquiring magnetic information in the inspection object based on the detection results of the three-axis magnetic sensor for inspection and the three-axis magnetic sensor for compensation. The nondestructive inspection method according to claim 1.   The step of obtaining the magnetic information in the inspection object includes the step of combining the three-axis magnetic components detected by the three-axis magnetic sensor for inspection into one waveform and detecting the result by the three-axis magnetic sensor for compensation. The non-destructive inspection method according to claim 2, further comprising a step of acquiring the magnetic information in the inspection object by compensating the obtained three-axis magnetic components into a single waveform and compensating for the result.   The step of acquiring the magnetic information in the inspection object includes, in a state in which the geomagnetic component is reduced from the detection result of the three-axis magnetic component, one waveform obtained by combining the three-axis magnetic components in the inspection object. The nondestructive inspection method according to any one of claims 1 to 3, further comprising a step of acquiring the information as magnetic information.   The non-destructive inspection method according to any one of claims 1 to 4, wherein the step of acquiring the magnetic information in the inspection target includes the step of acquiring magnetic information of a reinforcing bar in the concrete.

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