JPH02213764A - Defect inspecting device - Google Patents

Abstract

PURPOSE:To obtain a SQUID measuring system which operates stably in a sweeping magnetic field and can detect corrosion and cracks by feeding back the output signal of the SQUID to the pickup coil of the SQUID. CONSTITUTION:A cryostat 40 housing a superconducting coil as an excitation coil 20, an SQUID sensor 50, a pickup coil 51, and a magnetic body 60 for balancing is disposed in the upper part of a measuring body 1. A refrigerant 41, such as liquid He, is packed in the cryostat 40 and is kept at the working temp. of the SQUID element 50 and the superconducting excitation coil 20. The excitation coil 20 is controlled by an excitation controller 21 and impresses a cyclic magnetic field to the measuring body 1. The previously determined magnetic characteristics when there are no corrosion and cracks are previously stored in a data base 72 and the degrees of the cracks and corrosion of the measuring body 1 are decided from the comparison and computation of the data measured with an arithmetic device 70 and the data base 72.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an apparatus for inspecting corrosion, cracks, etc. of metal materials, and in particular, a 5Q device that can be tracked in a variable excitation magnetic field.
The present invention relates to a U4D sensor measuring device.

[Conventional technology]

In conventional devices, as described in Japanese Patent Laid-Open No. 60-12838, a -like uniform magnetic field is formed using a superconducting magnet, and biomagnetism is detected using a SQUID.

The superconducting magnet at this time was used in persistent current mode.

[Problem to be solved by the invention]

In the above conventional technology, a superconducting magnet is used in persistent current mode to obtain a uniform magnetic field, and no consideration is given to a method of inspecting using a SQUID while sweeping the magnetic field. There was a problem that SQUIDs did not work in swept magnetic fields due to drift and noise.

An object of the present invention is to provide an IUID measurement system that operates stably in a sweeping magnetic field and is suitable for detecting corrosion, cracks, etc.

[Means to solve the problem]

The above purpose is to feed back the output signal of the SQUID to the pickup coil of the SQUID in order to cancel the drift and noise of the SQUID caused by sweeping the magnetic field.
This is achieved by providing an automatic balancing mechanism.

[Effect]

Cycling the current of a superconducting magnet without a measuring object
SQUI that occurs when applying to IC and sweeping the magnetic field
D drift and noise are detected, this signal is fed back, and the drift magnetic field and noise magnetic field are canceled out and balanced automatically by controlling the position of the magnetic material and canceling coil provided in the pickup coil section of the SQUID. When this state is stored and the object to be measured is inspected, the position of the magnetic body and the cancellation coil are controlled using the information of the state in which there is no object to be measured, and information on the magnetic properties of only the object to be measured is obtained.

In this way, magnetic information of the object to be measured can be obtained while the magnetic field is sweeping, so that magnetic changes due to corrosion, cracks, etc. in the object to be measured can be detected with high sensitivity using the SQUID.

〔Example〕

Next, an embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example of a system configuration for implementing the present invention using a SQUID sensor. In the figure, reference numeral 1 denotes a measurement object such as equipment or piping used in thermal power plants, Ifi child power plants, chemical plants, and the like. 20 is an excitation coil for exciting the measurement object, and 21 is a magnetization controller for the excitation coil. 40 is a taliostat for maintaining the SQUID sensor at an operating temperature.

41 is a refrigerant. 50 is a SQUID element.

51 is a SQUID pickup coil. 52
is the head amplifier of the SQUID sensor, and 53 is the SQ
This is a UID sensor controller. 60 is a magnetic material for balancing the pickup coil 51.

61 is a drive device that controls the position of the balancing magnetic body, and 62 is a controller for the drive device 61. 70 is an arithmetic unit that performs signal processing and control of the magnetization controller 3, SQUID sensor controller 53, and drive device controller 62. 71 is an output device for displaying the results of the arithmetic device 7o, and 72 is a database of the arithmetic device 70. Furthermore, 80.

This is an observation device for observing the surface condition of the measurement object 1. As the observation device 80, an optical camera or the like can be used. 81 is a controller of the observation device 80.

A superconducting coil as an excitation coil 20 is placed above the measurement object 1,
SQUID sensor 50. A cryostat 40 containing a pickup coil 51 and a balancing magnetic body 60 is arranged. The inside of the cryostat 40 is filled with a coolant 41 such as liquid He, and maintained at the operating temperature of the SQUID element 50 and the superconducting excitation coil 20. The excitation coil 20 is controlled by an excitation controller 21 and applies a cyclic magnetic field to the measurement object l.

In order to eliminate magnetic drift and noise that occur in the pickup coil 51 when excited by the superconducting excitation coil 20, a balancing magnetic body 60 is placed near the pickup coil 51 and the position of the magnetic body 6° is controlled. Magnetic drift and noise occurring in the pickup coil 51 are canceled.

A detailed example of this will be explained using FIGS. 2 to 8.

FIG. 2 is an example of the balancing magnetic body 6o.

A donut-shaped balance magnetic body 60 is arranged above the pickup coil 51, and a shaft 850 for driving the magnetic body 6o up and down is attached to the magnetic body 6o. shaft 6
50 to move the balance magnetic body 60 up and down, SQ
The output of the UID sensor can be adjusted to zero.

By making the balance magnetic body 60 into a donut shape, the magnetic flux spreading above the pickup coil 51 can be narrowed down, so that a −-like magnetic field can be locally formed.

FIG. 6 shows the relationship between the position of the balancing magnetic body 60 and the output of the SQUID sensor. By changing the position of the balance magnetic body 60, the output of the 5QtOD sensor changes as shown by the solid line. Furthermore, when a current is applied to the superconducting excitation coil 20, the characteristic curve becomes like a broken line.

Conversely, when the polarity of the current flowing through the superconducting excitation coil 20 is changed, the characteristics become as shown by the dashed line. That is, even if the current of the superconducting excitation coil is changed cyclically, the SQU
The output of the ID sensor can always be maintained at zero. This state is shown in FIG. 7, which shows the relationship between the magnetic field of the superconducting excitation coil 20 and the position of the balancing magnetic body 60 when the output of the SQUID sensor is maintained at zero.

This state is stored in the database 72.

FIG. 8 shows an example of the results measured using the system of the present invention. SQ of the measured object when there is no corrosion or cracking shown by the solid line
Measurement results of UID output and magnetic field strength are obtained in advance in a database. This data can also be obtained from the B-H curve of the measuring object.

Next, the results of measuring a measurement object with cracks or corrosion are shown by broken lines and dashed-dot lines.

In the case of corrosion 5 For example, due to an increase in the magnetic properties or thinning of the corrosion product of the measurement object, the magnetic properties of the corrosion product exhibit the characteristics shown by the dashed line.The magnetic properties of the corrosion product are determined by the material of the measurement object. Data on ingredients and use environment are input into the database 72 in advance.

In the case of a crack, changes in magnetic permeability due to plastic deformation in the vicinity of the crack and disturbance of the magnetic field due to the crack occur, resulting in the characteristics shown by the broken line.

In this way, it is detected how the data of the measuring object changes with respect to the SQUID output and magnetic field strength data in the case where there is no corrosion or cracking shown by the solid line in FIG.

According to this embodiment, the magnetic signal for balance can be measured with high precision even in the cyclic magnetic field generated by the excitation coil.

FIG. 3 shows another embodiment of the balancing magnetic body 60.

The balance magnetic body 60 has a conical shape and is arranged with its apex facing toward the top of the pickup coil 51. By arranging the magnetic body 60 in this manner, the magnetic flux spreading above the pickup coil 51 can be narrowed down, so that a locally uniform magnetic field can be formed.

FIG. 4 shows another embodiment of the balance magnetic body 60.

The balance magnetic body 60 has a conical shape and is arranged with the bottom surface facing the top of the pickup coil 51. By arranging the magnetic body 60 in this manner, the magnetic flux distribution above the pickup coil 51 can be made uniform, so that a locally uniform magnetic field can be formed.

FIG. 5 shows an example in which there are a plurality of balancing magnetic bodies 60. A donut-shaped balance magnetic body 600 is placed on the top of the pickup coil 51, and a cylindrical magnetic body 601 is placed in the center of the donut-shaped balance magnetic body 600.
are arranged, and shafts 650 and 651 are attached to the magnetic bodies 600 and 601 to drive them up and down. The magnetic bodies 600 and 601 are moved up and down to obtain uniformity of the magnetic field.

According to this embodiment, the magnetic field of the pickup coil portion of the SQUID sensor can be adjusted uniformly, so even if the magnetic field of the excitation coil applied to the object to be measured is cyclically changed, stable measurement can be performed with the SQUID sensor.

Another embodiment is shown in FIG. 10. In this embodiment, SQU
A balance coil is arranged near the pickup coil 50 of the ID sensor, and the balance coil allows the SQ
Adjust the output of the UID sensor.

In the 10th IA, balance coils 620° and 621 are placed above and below the pickup coil 50 of the SQUID sensor.

By adjusting the current flowing through the balance coils 620 and 621, the magnetic field near the pickup coil 51 can be made uniform, so that the output of the SQUID sensor can be balanced.

Furthermore, when a current is applied to the superconducting excitation coil 20,
Alternatively, the current of the superconducting excitation coil 20 may be changed to cyclic
Even when changed to 620.621
By controlling the current of the SQUID sensor, the output of the SQUID sensor can always be maintained at zero. Excitation coil 2 in this state
0 current and the currents of the balance coils 620 and 621 are stored in the database 72.

Similarly, in this example, as shown in FIG. 8, the measurement results of the SQUID output and magnetic field strength of the object to be measured in the case where there is no corrosion or cracking, as shown by the solid line, are obtained in advance in the database, and to detect how the data of the measuring object is changing.

According to this embodiment, the balance coil can electrically balance even the cyclic magnetic field generated by the excitation coil, and magnetic signals can be measured with high precision.

Another embodiment is shown in FIG. 11. In this embodiment, SQU
A superconducting transformer is disposed between the pickup coil of the ID sensor and the SQUID element, and a balance coil is disposed coupled to the superconducting transformer, and the output of the SQUID sensor is adjusted by the balance coil.

In FIG. 11, the input coil 631 of the pickup coil 50 of the SQUID sensor, the output coil 632 to the SQUID element, and the balance coil 630 are coupled to form a superconducting transformer.

By adjusting the current flowing through the balance coil 630, it is possible to cancel the noise caused by the disturbance of the magnetic field near the pickup coil 51, so that the output of the SQUID sensor can be balanced.

Furthermore, when a current is applied to the superconducting excitation coil 20,
Alternatively, the current of the superconducting excitation coil 20 may be changed to cyclic
By controlling the current of the balancing coil 630, the output of the SQUID sensor can always be maintained at zero even when the current is changed to zero. The current of the exciting coil 20 and the current of the balance coil 630 in this state are stored in the database 72.

Similarly, in this example, as shown in FIG. 8, the measurement results of the SQUID output and magnetic field strength of the object to be measured in the case where there is no corrosion or cracking, as shown by the solid line, are obtained in advance in the database, and Detect whether the data of the object to be measured changes as follows.

According to this embodiment, electrical balance can be achieved by the balancing coil regardless of changes in the pickup coil of the SQUID, and magnetic signals can be measured with high precision.

FIG. 12 shows an example in which the system of the present invention is attached to a mobile robot or the like as a movable drive device.

The inspection device 2 of the present invention is attached to the tip of an articulated robot 3 and scans the surface of the object 1 to detect cracks, defects, shape changes, corrosion conditions, etc. 4 is a controller of the inspection apparatus 2 of the present invention, and 5 is a controller of the articulated robot 3.

FIG. 9 is a flowchart diagram of the present invention.

The operation will be explained below according to the flowchart.

5 tart: staρ1: Input and initialization of vA constant conditions.

Initialize the articulated robot 3 shown in FIG. 12, input the measurement range and starting position from the robot controller 5, and set the excitation current of the inspection device 2 to 81! l Enter measurement conditions such as constant sensitivity.

5top2: Move the sensor to the inspection position.

Inspection equipment! ! 2 to a measurement position, and the surface condition at the measurement position is recorded in the memory 72 using an observation device 80 shown in FIG.

atap3: Sweep the magnetic field of the excitation magnet.

The current of the superconducting excitation coil 20 is changed cyclically. At this time, in order to remove drift and noise occurring during the excitation process, data on position control and current control of the balance magnetic body 60, balance coils 620, 630, etc. is read out from the memory 72 and calibrated.

Memorize the SQUID sensor signal.

of the magnetic field of the excitation coil 20 at the measurement position. 5 step 4: SQUID sensor during sweep The signal is stored in memory 72.

5tap5: Next, move to the measurement position.

The inspection device 2 is operated by the articulated robot 3. Move to the next measurement position.

gtep6: Determine whether it is the final position.

yes; 5top 7 no: 5top 2 5top7: Map the SQUID sensor signal.

reading out the measured data from the memory 72 and performing mapping by imaging with the arithmetic unit 70;
This is displayed in the output bag [71].

5top8: Image analysis, patterning calculation device 70
The mapping data imaged with is patterned and damage is estimated.

5top9: Determine whether to re-measure or end based on abnormal value determination.

yes; 5top 2 no; end to end: 5tep 7 to 5tep of the flowchart in Figure 9
9 will be explained in detail using FIGS. 13 to 18.

The details of mapping of 5top 7 are described below.

FIG. 13 is an example of data determined at 11 m. S Q U I Dsign associated with excitation of superconducting excitation coil 20
al change, and the signal when there is no measuring object sample is always set to zero, and the S Q U I Dsigna for that
This shows the change in l. The data at this point is organized and mapped within an arbitrary range.

FIGS. 15 and 16 show mapping data in an arbitrary range. FIG. 15 shows the case where the excitation magnetic field is large, and FIG. 16 shows the case where there is no excitation. The state of the 0 surface is obtained from the data of the observation bag [80]. This observation device 80
Data and this inspection device i! The two magnetic data are combined and imaged by mapping.

The details of mapping for 1itep 8 are described below.

FIG. 14 shows the measured data in FIG. 13 further standardized by the signal in the case of no defects, and S Q U
It is classified into a plurality of patterns based on changes in IDsignal. This patterning is shown in Figures 15 and 1.
Applying it to Figure 6, compare each signal change part with each pattern,
Estimate damage.

FIG. 17 is an example of a display screen of the output device 71.

An overall view of the measuring object 1 is shown on the screen, and the results measured by the inspection device 2 are displayed in different colors. Displays the level of each color on the screen,
Level selection instruction marks 901 and 902 are displayed so that a specific level range can be arbitrarily selected, and the signal level is selected using the level selection instruction marks 901 and 902.

Furthermore, when viewing the results of only the local region 911, the region is selected using the local region designation mark and the line 910 indicating the range, and displayed in an arbitrary enlargement on the next screen. An example of this is shown in FIG. 18, which shows an abnormal defect state 920 in the 0 local area 911.

According to this embodiment, the measurement result is displayed as an image, and the damage to the object to be measured can be easily determined and measured with high accuracy by patterning the signal by image analysis.

(Effects of the Invention) According to the present invention, a SQUID sensor can operate stably even in a magnetic field swept by a mechanism such as a balancing magnetic body or a coil, and corrosion, cracks, etc. can be detected with high accuracy by patterning analysis of images. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram of an embodiment of the present invention, Figs. 2 to 5 are schematic diagrams for explaining the operation of embodiments of the magnetic material for balance of the present invention, and Fig. 6 is a system configuration diagram of an embodiment of the present invention. A characteristic diagram showing the relationship between the position of the magnetic body and the signal of the 5QtJID sensor, Figure 7 shows the slgunal of the SQUID sensor.
A characteristic diagram showing the relationship between the strength of the magnetic field of the superconducting excitation coil and the position of the balancing magnetic body when the FIG. 9 is an operation flowchart of the system according to the embodiment of the present invention. Fig. 10 is a device configuration diagram of an embodiment in which a balancing coil is arranged in the pickup coil part of the SQUID sensor, and Fig. 11 shows a superconducting transformer provided between the pick-up coil and the element part of the SQUID sensor, and this superconducting transformer. A device configuration diagram of an embodiment in which a balance coil is combined with the
FIG. 12 is a device configuration diagram showing an embodiment in which the inspection device of the present invention is attached to an articulated robot, FIG.
Figure 4 shows the SQ associated with the strength of the magnetic field of the superconducting excitation coil.
A characteristic diagram showing changes in the signal of the UID sensor,
FIGS. 15 and 16 are schematic diagrams showing the measurement results as images, and FIGS. 17 and 18 are schematic diagrams showing the screen state of the output device. 1... Measuring object, 2... Inspection device of the present invention, 3...
Articulated robot, 4... Controller of inspection equipment, 5
... Controller of articulated robot, 20 ... Excitation coil, 21 ... Magnetization controller, 40 ... Taliostat, 41 ... Refrigerant, 50 ... SQUID
Element, 51... SQUID pickup coil, 5
2...SQUID sensor head amplifier, 53...
SQUID sensor controller, 60... balance magnetic body, 61... balance magnetic body drive device, 6
2... Controller of drive device, 70... Arithmetic device, 71... Output device, 72... Database, 80
...Observation device, 81...*6 device controller,
600...doughnut-shaped balance magnetic material, 601.
...Cylindrical magnetic body, 620.621,630...Balance coil, 631...Input coil of pickup coil, 632...Output coil to SQUID element, 650,651...Shaft, 901 ,902...
・Level selection instruction mark, 910...Local area instruction mark and line indicating range, 911...Local area, 920・
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Claims (1)

[Scope of Claims] 1. In an inspection device that detects the degree of cracks, corrosion, etc. from magnetic changes occurring in a measuring object, an excitation device that applies a magnetic field to the measuring object, and thereby controlling the saturation magnetism of the measuring object. , a magnetic measurement device that detects magnetic properties such as residual magnetism, coercive force, Barkhausen noise, etc., a database of magnetic properties obtained in advance without cracks or corrosion, and a comparison calculation between the measured data and the database. A defect inspection device comprising: an arithmetic device that determines the degree of cracking or corrosion of the object to be measured. 2. A defect inspection device according to claim 1, characterized in that a superconducting excitation coil is used as an excitation device for applying a magnetic field to the object to be measured, and the superconducting excitation coil has a variable excitation function. 3. According to claim 1, the magnetic measuring device for detecting the magnetic properties of the object to be measured is provided with a function of automatically balancing in response to variable excitation of the excitation coil. Defect inspection equipment. 4. Claim 3, wherein a SQUID sensor is used as the magnetic measurement device for detecting the magnetic properties of the object to be measured, a magnetic body is arranged near a pickup coil for magnetic detection, and a position control mechanism is provided on the magnetic body. A defect inspection device characterized by being provided with. 5. A defect inspection device according to claim 4, characterized in that a plurality of the magnetic bodies are arranged and a position control mechanism is provided for each. 6. In claim 3, a SQUID sensor is used as the magnetic measurement device for detecting the magnetic properties of the object to be measured, and a balance coil is disposed near a pickup coil for magnetic detection, and the balance coil Tsute SQUI
A defect inspection device characterized by being provided with a D sensor output balance mechanism. 7. In claim 3, a SQUID sensor is used in the magnetic measurement device for detecting the magnetic properties of the object to be measured, and a superconducting transformer is disposed between the magnetic detection pickup coil and the SQUID element, and further, A defect inspection device characterized in that a balancing coil is disposed coupled to the superconducting transformer, and the balancing coil provides an output balancing mechanism for a SQUID sensor. 8. A defect inspection device according to claim 1, wherein the inspection device is attached to a movable drive device such as a mobile robot, thereby making it possible to inspect an actual machine. 9. Claim 1 is characterized in that the output device for displaying the results of the arithmetic device has a function of displaying the detection results of cracks and corrosion on a contour map or a bird's-eye view contour map. Inspection equipment for defects. 10. In claim 1, the output device for displaying the results of the arithmetic device displays the entire image of the measuring device, the measurement range and the measurement results are displayed in different colors, and the local area is indicated by an instruction mark. A defect inspection device characterized by having a function of being able to select a local area, displaying this local area as a separate image as an enlarged view, and displaying the detection results of cracks and corrosion as a perspective image or a bird's-eye view contour map.