Thickness detection device, thickness detection method, and thickness monitoring method

Abstract

To provide a thickness detection device capable of detecting a portion where the thickness becomes thin regardless of a position where the thickness of a measurement target becomes thin.SOLUTION: A torus-like magnetic flux is generated in a state where a first magnet 14 and a second magnet 16 are brought into contact with a measurement target 8. The resulting magnetic leakage flux Φ is detected by a hall element 18, enabling detection of the thickness of the measurement target 8. Since the torus-like magnetic flux is generated, the magnetic leakage flux Φ can be detected regardless of a portion where the thickness becomes thin, thereby enabling detection of the portion where the thickness becomes thin.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a wall thickness detection device that detects the wall thickness of a measurement object, and a wall thickness detection method and a wall thickness monitoring method using the wall thickness detection device. [Background technology]

[0002] Metallic parts are generally used in various parts such as pipes in factories and bridges, and may become thinner than they were initially due to aging caused by various reasons. Thinning of metal parts may cause sudden trouble. For example, thinning of steel materials such as pipes in factory equipment may cause the factory to stop operating, resulting in lost opportunities. For this reason, it is essential to grasp or predict the thickness of metallic parts in advance in order to use the metallic parts stably.

[0003] Various non-destructive inspection methods are known as methods for detecting wall thickness, among which a leakage magnetic flux inspection method using magnetism is known. For example, in Patent Document 1, a magnetic field is generated near the object to be measured by a predetermined magnetization means, and leakage magnetic flux generated due to corrosion or the like is detected by a magnetic sensor such as a Hall element to detect the wall thickness. In Patent Document 2, the object to be measured is magnetized by a permanent magnet, and the leakage magnetic flux is detected by a magnetic sensor using the magnetoresistance effect to detect the wall thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6296851 [Patent Document 2] JP 2018-128450 A Summary of the Invention [Problem to be solved by the invention]

[0005] The exciter (magnetizer) proposed in the above Patent Documents 1 and 2 is formed in a U-shape as a whole, and a unidirectional magnetic field is applied to the object to be measured by using this exciter. However, when the above exciter is used to detect the wall thickness of a wide area, it is necessary to install multiple exciters. For example, when the object to be measured is a cylindrical pipe, it is possible to arrange U-shaped exciters at equal angular intervals along the circumferential direction of the object to be measured, and further arrange them in parallel at predetermined intervals in the longitudinal direction of the pipe. However, depending on the arrangement pattern of the exciters, the change in leakage magnetic flux density when the wall thinning occurs becomes non-uniform. In relation to this, depending on the relative position between the exciter and the part where the wall thinning occurs, the leakage magnetic flux density may not exceed the threshold value of the magnetic sensor, and the wall thinning may not be detected.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a wall thickness detection device that can detect areas where the wall thickness is thin, regardless of the relative position of the wall thickness detection device with respect to the object to be measured, and a wall thickness detection method and wall thickness monitoring method using the wall thickness detection device. [Means for solving the problem]

[0007] According to one aspect of the present invention, a thickness detection method for detecting the thickness of a measurement object includes forming a torus-shaped magnetic circuit that includes a part of the measurement object in its path and generates magnetic flux in a poloidal direction, and arranging a plurality of magnetic detection elements in the toroidal direction on the measurement object inside a poloidal cross section cut by a plane passing through the center line of the torus within the magnetic circuit, and detecting magnetic flux leaking from the measurement object using the magnetic detection elements.

[0008] According to this method of detecting thickness, a torus-shaped magnetic flux is generated by including a part of the object to be measured in its path, and the magnetic flux leaking from the object to be measured when the thickness of the object to be measured is reduced is detected by the magnetic detection element, so that the part of the object to be measured where the thickness is reduced can be detected. Since the magnetic flux is generated in a torus shape and distributed substantially uniformly, the leaked magnetic flux can be detected regardless of the part where the thickness is reduced, and the part where the thickness is reduced can be detected. In this specification, "detecting the thickness" may mean measuring the value of the thickness, or may mean detecting the change in thickness over time or the distribution of the thickness.

[0009] In the above-described thickness detection method, preferably, a plurality of the torus-shaped magnetic circuits are formed along a surface of the object to be measured, and a plurality of the magnetic detection elements are arranged in a toroidal direction for each of the torus-shaped magnetic circuits.

[0010] According to this method of detecting thickness, by forming a plurality of magnetic circuits along the surface of the object to be measured, it is possible to detect areas of the object to be measured where the thickness is thin over a wide range.

[0011] In addition, a thickness detection device according to one embodiment of the present invention is characterized in that it comprises a magnetic field generating source configured so that one of a pair of magnetic poles surrounds the outer edge of the other magnetic pole, and a plurality of magnetic detection elements arranged between the one magnetic pole and the other magnetic pole.

[0012] According to this configuration, a magnetic flux is generated with one magnetic pole and the other magnetic pole in contact with the object to be measured, and the leakage magnetic flux generated at this time is detected by the magnetic detection element, thereby making it possible to detect the portion of the object to be measured where the thickness has become thin. Furthermore, with the above configuration, the magnetic flux is generated uniformly, so that it is possible to detect the leakage magnetic flux regardless of the relative position between the thickness detection device and the portion where the thickness has become thin, and it is possible to preferably detect the portion where the thickness has become thin.

[0013] In the above-mentioned thickness detection device, preferably, the device comprises a first magnet constituting the other magnetic pole, a second magnet constituting the one magnetic pole and arranged to surround the outer edge of the first magnet and having a magnetic pole orientation opposite to that of the first magnet, a yoke connecting the first magnet and the second magnet, and a plurality of the magnetic detection elements arranged between the first magnet and the second magnet.

[0014] This type of wall thickness detector can generate a torus-shaped magnetic flux by a first magnet and a second magnet arranged to surround the outer edge of the first magnet. Also, by connecting the first magnet and the second magnet to a yoke, a strong magnetic field can be generated by the yoke without using a magnet with a complex shape.

[0015] In the above-mentioned thickness detection device, preferably, the yoke is formed in an umbrella shape, the first magnet is composed of a rod-shaped permanent magnet, the second magnet is composed of an annular permanent magnet, one end of the first magnet in the longitudinal direction is connected to the center of the yoke, and one end of the second magnet is connected to the peripheral portion of the yoke.

[0016] According to this configuration, by using permanent magnets as the first magnet and the second magnet to generate a torus-shaped magnetic flux, power consumption can be reduced compared to using electromagnets. Also, the device can be configured with permanent magnets of relatively simple shapes, such as rod-shaped magnets and ring-shaped magnets. Furthermore, by forming the second magnet into a ring shape, a uniform magnetic flux can be generated.

[0017] In the above thickness detection device, preferably, the second magnet has a peripheral portion formed in a hexagonal shape.

[0018] According to this configuration, since the second magnet is formed in a hexagonal shape, multiple thickness detection devices can be arranged closely together around the object to be measured, making it possible to detect all areas of the object to be measured where the thickness is thin.

[0019] In addition, the thickness detection device is preferably configured to generate a torus-shaped magnetic flux including the object to be measured in a path thereof while the first magnet and the second magnet are in contact with the object to be measured, and to detect portions of the object to be measured where the thickness is thin by detecting the magnetic flux leaking from the object to be measured with the magnetic detection element.

[0020] According to this configuration, the wall thickness detector can be easily attached to the object to be measured so that the object to be measured becomes part of the torus-shaped magnetic flux.

[0021] Moreover, a method for monitoring thickness according to one aspect of the present invention monitors the thickness of a measurement object constituting a specific facility by using the above-described method for detecting thickness while the specific facility is in operation.

[0022] According to this method, by using the above-mentioned thickness detection method, the thickness of the object to be measured can be monitored while the equipment is in operation.

[0023] In addition, a method for monitoring wall thickness according to one aspect of the present invention includes disposing the above-mentioned wall thickness detection device on a surface of a measurement object that constitutes part of a specified facility, and monitoring the wall thickness of the measurement object while the facility is operating.

[0024] According to this method, the thickness of the object to be measured can be monitored by using the above-mentioned thickness detection device while the equipment is in operation.

[0025] In the above-mentioned method for monitoring wall thickness, preferably, a plurality of the wall thickness detection devices are arranged in a line on the surface of the object to be measured, and the wall thickness of the object to be measured is monitored.

[0026] According to this method, by arranging thickness detection devices in a line on the surface of the object to be measured, it is possible to monitor the thickness over a wide range of the object to be measured.

[0027] In the above-mentioned wall thickness monitoring method, preferably, the object to be measured is a pipe of the facility, and the wall thickness detection device is disposed on a surface of a bent portion of the pipe.

[0028] According to this method, the wall thickness detector can be disposed on the surface of the bent portion of the pipe where the wall thickness is likely to decrease, so that the wall thickness detector can be used efficiently.

[0029] Preferably, the magnetic detection element is a Hall element or a Wiegand element, which makes it possible to preferably detect magnetic flux leaking from the object to be measured when the wall thickness is reduced. Effect of the Invention

[0030] As described above, it is possible to provide a wall thickness detection device, a wall thickness detection method, and a wall thickness monitoring method that can detect a portion where the wall thickness is thin, regardless of the relative position between the wall thickness detection device and the portion where the wall thickness of the object to be measured is thin. [Brief description of the drawings]

[0031] [Figure 1] 1 is a perspective view showing an external appearance of a wall thickness detection device according to one embodiment of the present invention; [Diagram 2] This is a cutaway model of the wall thickness detection device in FIG. [Diagram 3] FIG. 13 is an image diagram showing a state in which a torus-shaped magnetic flux is generated. [Figure 4] FIG. 1 shows the wall thickness detector as viewed from the center line direction. [Diagram 5] 2 is a cross-sectional view of the thickness detection device of FIG. 1 cut at a position including a Hall element in the toroidal direction. [Figure 6] 6 is a diagram showing a state in which thinning occurs in the measurement object in FIG. 5. FIG. [Figure 7] 1 is a diagram conceptually illustrating the state of a wall thickness detection device when a wall thickness reduction occurs in an object to be measured due to corrosion or the like. FIG. [Figure 8] 1 is a diagram for simply explaining a system configuration for detecting the thickness of a measurement object, the system configuration including a thickness detection device. FIG. [Figure 9] FIG. 9 is a circuit diagram corresponding to the system configuration of FIG. [Figure 10] 4 is a flowchart for explaining a wall thickness detection method. [Figure 11] FIG. 1 is a diagram showing an L-shaped pipe constituting a part of a plant facility to which a wall thickness monitoring method is applied. [Figure 12] 12 is a view seen from the direction of arrow G in FIG. [Figure 13] FIG. 1 is a diagram showing the configuration of a wall thickness monitoring system configured by distributing a plurality of wall thickness detection devices in a predetermined area of ​​an L-shaped pipe. [Figure 14] FIG. 11 is a perspective view of another embodiment of the wall thickness detecting device, the peripheral portion of which is formed in a hexagonal shape. [Figure 15] 15 is a diagram showing a state in which the thickness detection devices shown in FIG. 14 are laid out over a predetermined portion of a measurement object. FIG. [Figure 16] FIG. 11 is a cross-sectional view of a wall thickness detector in which a plurality of Wiegand elements are used instead of a plurality of Hall elements used in the wall thickness detector. [Figure 17] FIG. 1 is a diagram illustrating the properties of a Wiegand element. [Figure 18] FIG. 13 is a diagram showing an example of a circuit for processing the output of a Wiegand element when a Wiegand element is used. [Figure 19] 10 is a flowchart for explaining a method for detecting a wall thickness when a Wiegand element is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, a wall thickness detection device 10, which is one embodiment of the present invention, and a wall thickness detection method and a wall thickness monitoring method using the wall thickness detection device 10 will be described with reference to the drawings. Note that the scope of the invention is not limited to the disclosed embodiment. Also, components with the same reference numerals in each drawing are the same components, and their description will be omitted as appropriate.

[0033] [Structure of wall thickness detection device] Fig. 1 is a perspective view showing the outer shape of a wall thickness detector 10 according to an embodiment of the present invention. The wall thickness detector 10 includes a yoke 12, a first magnet 14 (hereinafter, first magnet 14), and a second magnet 16 (hereinafter, second magnet 16). Although omitted in Fig. 1, the wall thickness detector 10 also includes a plurality of Hall elements 18 (see Fig. 4, etc.), which will be described later.

[0034] The yoke 12 is formed with an umbrella-shaped exterior with a solid interior, and connects between the first magnet 14 and the second magnet 16. The yoke 12 is formed in a circular shape when viewed from a direction along a center line CL passing through the center of the yoke 12. The yoke 12 is preferably made of a soft magnetic material such as, for example, electromagnetic soft iron (pure iron), electromagnetic steel sheet, electromagnetic stainless steel, SMC (soft magnetic composite material), or the like.

[0035] The first magnet 14 is made of a cylindrical (rod-shaped) permanent magnet. One end of the first magnet 14 in the longitudinal direction is connected to the center of the yoke 12.

[0036] The second magnet 16 is composed of a cylindrical (annular) permanent magnet. One end of the second magnet 16 in a direction parallel to the center line CL (hereinafter, the center line direction) is connected to the circular peripheral edge of the yoke 12. The outer shape of the second magnet 16 seen from the center line direction is the same as the peripheral edge of the yoke 12. The second magnet 16 is arranged so as to surround the outer edge of the first magnet 14. Therefore, the first magnet 14 is arranged on the inner circumference of the second magnet 16 formed in a cylindrical shape. In relation to this, an annular space S is formed between the first magnet 14 and the second magnet 16. The yoke 12 is arranged so as to block one end of the annular space S formed between the first magnet 14 and the second magnet 16 in the center line direction.

[0037] When the second magnet 16 is connected to the yoke 12, the direction of the magnetic poles along the center line CL is opposite to that of the first magnet 14. That is, the first magnet 14 and the second magnet 16 are connected to the yoke 12 with their poles facing different directions. In relation to this, the first magnet 14 and the second magnet 16 also have poles different from each other at the ends opposite the yoke 12 in the center line direction. Note that the first magnet 14 corresponds to the other magnetic pole of the pair of magnetic poles in the claims, and the second magnet 16 corresponds to one magnetic pole of the pair of magnetic poles in the claims.

[0038] 2 is a cut model of the wall thickness detector 10 of FIG. 1. As shown in FIG. 2, the wall thickness detector 10 is attached to the object 8 to be measured so that the opening of the annular space S formed between the first magnet 14 and the second magnet 16 is blocked by the object 8. That is, the wall thickness detector 10 is attached to the object 8 to be measured in a state where the end faces of the first magnet 14 and the second magnet 16 located on the opposite side to the yoke 12 in the center line direction are in contact with the object 8. At this time, magnetic flux is generated in the yoke 12, the first magnet 14, and the second magnet 16 in the direction indicated by the arrows. Magnetic flux is also generated in the object 8 to be measured in the direction indicated by the arrows.

[0039] Specifically, a torus-shaped magnetic flux is generated as indicated by the arrow in Fig. 3, including the first magnet 14, the second magnet 16, the yoke 12, and the object to be measured 8 in the path. Specifically, the magnetic flux in the direction along the circumferential surface of the torus (poloidal direction) indicated by the arrow in Fig. 3 is generated uniformly in the rotation direction (toroidal direction) based on the center line CL of the torus. In this way, a torus-shaped magnetic circuit 17 is formed in which magnetic flux is generated in the poloidal direction, including the yoke 12, the first magnet 14, the second magnet 16, and a part of the object to be measured 8 in the path. In addition, the yoke 12, the first magnet 14, and the second magnet 16 form a magnetic field generating source 15 that generates a torus-shaped magnetic flux.

[0040] Fig. 4 is a view of the wall thickness detector 10 of Fig. 1 as viewed from the center line direction. As shown in Fig. 4, a plurality of Hall elements 18 are arranged in an annular space S formed between the first magnet 14 and the second magnet 16. In this embodiment, eight Hall elements 18 are arranged at equal angular intervals in the toroidal direction. Each Hall element 18 is arranged at or near the middle of the first magnet 14 and the second magnet 16 in the radial direction centered on the center line CL.

[0041] When a current flows through the Hall element 18 and the current and magnetic flux intersect, a voltage (Hall voltage) is generated in a direction perpendicular to the direction of the current and the direction of the magnetic flux due to the Hall effect, and this voltage is amplified to output a Hall voltage proportional to the magnetic flux density of the magnetic flux. In this embodiment, the Hall element 18 is used as the magnetic detection element, but anything other than the Hall element 18 that can detect magnetism may be used. For example, a magnetoresistance element, a TMR element, a GMR element, a Wiegand element, etc. may be used.

[0042] 5 is a simplified cross-section (poloidal cross-section) of the thickness detector 10 cut at a position including the Hall element 18 in the toroidal direction (rotation direction around the center line CL). That is, it corresponds to a poloidal cross-section of the thickness detector 10 cut at a plane passing through the center line CL. When the thickness detector 10 is viewed in the poloidal cross-section, the yoke 12, the first magnet 14, and the second magnet 16 form a substantially U-shape, and the ends of the first magnet 14 and the second magnet 16 abut against the object 8 to be measured, forming the closed-loop magnetic circuit 17. The magnetic circuit 17 is a closed-loop circuit in which magnetism circulates through the yoke 12, the first magnet 14, the second magnet 16, and a part of the object 8 to be measured.

[0043] 5, the Hall elements 18 are disposed in the closed-loop magnetic circuit 17 on the measurement object 8 located inside the poloidal cross section. Each Hall element 18 is electrically connected to a controller 20. The controller 20 supplies power to the Hall elements 18 to activate the Hall elements 18.

[0044] 6 shows a state in which the thickness of the measurement object 8 in FIG. 5 has been reduced due to corrosion, erosion, or the like caused by aging. When the thickness of the measurement object 8 is reduced, leakage magnetic flux Φ is generated, and the above-mentioned Hall voltage is generated due to the Hall effect. Therefore, the reduction in thickness can be detected by detecting this Hall voltage with the Hall element 18. In other words, the Hall element 18 functions as a sensor that detects the leakage magnetic flux Φ leaking from the measurement object 8. The detected Hall voltage is output to the controller 20 and processed as measurement data.

[0045] After supplying power to each Hall element 18, the controller 20 measures the output voltage output from each Hall element 18, and transmits the measured output voltage as measurement data to a management device 30 (described later). In this embodiment, the measurement data is transmitted to the management device 30, and the management device 30 estimates the portion where the wall thickness is thin based on the measurement data, and determines the occurrence of wall thinning.

[0046] 7 is a conceptual diagram showing the state of the wall thickness detector 10 when the wall thickness of the object 8 to be measured is reduced below the allowable value (threshold value) due to corrosion or the like. When the wall thickness detector 10 overlaps with the portion of the object 8 where the wall thickness is reduced (thinned portion) shown in FIG. 7, leakage magnetic flux Φ passes through the Hall elements 18 located within the area surrounded by the dashed line. In FIG. 7, the arrows shown on each Hall element 18 indicate the leakage magnetic flux Φ passing through each Hall element 18. In FIG. 7, the strength of the leakage magnetic flux Φ is represented by the thickness of the arrow, and the thicker the arrow, the stronger the leakage magnetic flux Φ.

[0047] In FIG. 7, the leakage magnetic flux Φ passing through the Hall element 18 located at the center among the three Hall elements 18 overlapping the thinned portion is strong, and the leakage magnetic flux Φ passing through the Hall elements 18 located on both sides is weaker than that of the center. Based on the difference in the magnitude of the leakage magnetic flux Φ detected by these three Hall elements 18, the part where the thickness of the measurement object 8 is thin can be estimated. In general, the thinner the part, the stronger the leakage magnetic flux Φ is, and the higher the output voltage (Hall voltage) output from the Hall element 18 is. Therefore, in FIG. 7, it can be estimated that the thickness of the measurement object 8 located near the Hall element 18 located at the center among the three Hall elements 18 is thinner than the thickness near the Hall elements 18 located on both sides. It can also be estimated that the thickness of the measurement object 8 starts to decrease near the Hall elements 18 located on both sides among the three Hall elements 18. Furthermore, in this embodiment, since a torus-shaped magnetic flux is generated, regardless of the relative positions of the wall thickness detection device 10 and the thinning portion of the object to be measured 8, leakage magnetic flux Φ is generated when a thinning portion is formed, and by detecting this leakage magnetic flux Φ, the thickness of the thinning portion can be detected without any leakage.

[0048] [Wall thickness detection method] Next, a method for detecting thickness using the thickness detector 10 will be described. Fig. 8 is a diagram for simply explaining a system configuration for detecting a portion of a measurement target 8 where the thickness is thin, the system configuration including the thickness detector 10, and Fig. 9 is a circuit diagram corresponding to the system configuration of Fig. 8. As shown in Figs. 8 and 9, a leakage magnetic flux detection circuit 24 (hereinafter, detection circuit 24) for detecting leakage magnetic flux Φ is configured including eight Hall elements 18, a controller 20, and a power source 22. In Figs. 8 and 9, each Hall element 18 is assigned a different reference numeral 18-1 to 18-8.

[0049] The controller 20 is connected to a power source 22 and is supplied with power from the power source 22. Furthermore, power is supplied to each of the Hall elements (18-1 to 18-8) from the power source 22 via the controller 20. In the detection circuit 24, when leakage magnetic flux Φ passes through at least one of the Hall elements (18-1 to 18-8), an output voltage (Vout_1 to Vout_8) according to the magnitude of the leakage magnetic flux Φ is output from the corresponding Hall element 18 to the controller 20. When the controller 20 measures the output voltages (Vout_1 to Vout_8) of the Hall elements (18-1 to 18-8), it wirelessly transmits the measurement data (voltage data) to the management device 30 via the first wireless device 26 and the second wireless device 28.

[0050] The management device 30 estimates the location of the thin wall based on the transmitted measurement data (voltage data). Specifically, it estimates the presence or absence of thin wall and its location based on the result of comparing the voltage indicated by the voltage data with a management value (threshold value). The management device 30 sequentially compares the voltage output from each Hall element 18 with the management value, and if the voltage exceeds the management value, it determines that thin wall has occurred at the location of the Hall element 18 that output the voltage, and if not, it determines that thin wall has not occurred.

[0051] Furthermore, when the management device 30 determines that thinning has occurred, the management device 30 displays information on the Hall element 18 that outputs a voltage indicating that thinning has occurred on a display device (not shown) as information on the location where thinning has occurred. For example, a computer having a server function is used as the management device 30. Alternatively, the management device 30 may be a computer (PC), tablet, smartphone, or the like used as a personal terminal.

[0052] A method for detecting a portion of the object 8 where the thickness is thin and determining the occurrence of thinning using the thickness detector 10 will be described with reference to the flow chart of FIG.

[0053] First, the thickness detector 10 is placed on the surface of the part of the object 8 to be measured, the thickness of which is to be grasped (step ST1). Next, after waiting for a predetermined time, power is supplied from the power source 22 to each Hall element 18 (step ST2). Next, the output voltage output from each Hall element 18 is measured (ST3). When the measurement of the output voltage of each Hall element 18 is completed, the measurement data (voltage data) is transmitted to the management device 30 (step ST4). Next, the management device 30 judges the presence or absence of thinning and its location based on the transmitted measurement data (step ST5). In the above flowchart, step ST1 corresponds to the process performed by the operator, steps ST2 to ST4 correspond to the process performed by the controller 20, and step ST5 corresponds to the process performed by the management device 30. Note that the estimation of the thickness and the judgment of thinning based on the measurement data may be performed by the controller 20, not by the management device 30. Although the thickness detection direction described above uses one thickness detection device 10, multiple thickness detection devices 10 can be arranged along the surface of the measurement object 8 to expand the measurement range. In this case, multiple magnetic circuits 17 that generate a torus-shaped magnetic flux on the surface of the measurement object 8 are formed, and multiple detection circuits 24 each including multiple Hall elements 18 are formed for each magnetic circuit 17.

[0054] [Thickness monitoring method] Next, a wall thickness monitoring method for monitoring changes in wall thickness of a pipe constituting a plant facility, for example, using the wall thickness inspection method using the wall thickness detection device 10 will be described. FIG. 11 shows an L-shaped pipe 102 constituting a part of a plant facility 100 to which the wall thickness monitoring method is applied. During operation of the plant facility 100, a predetermined fluid flows inside the L-shaped pipe 102, which is a part of the pipe. Since the L-shaped pipe 102 has a bent portion 104 bent at a substantially right angle, the direction of the flow of the fluid is changed inside the L-shaped pipe 102. In relation to this, the wall thickness is likely to become thin inside the bent portion 104 shown in FIG. 11 of the L-shaped pipe 102 because the fluid collides therewith. The wall thickness detection device 10 is disposed on the surface of the bent portion 104 of the L-shaped pipe 102, which is likely to become thin among such pipes. The L-shaped pipe 102 corresponds to the measurement object 8 described above.

[0055] FIG. 12 is a view of FIG. 11 as seen from the direction of arrow G. As shown in FIG. 12, seven wall thickness detectors 10 (wall thickness detectors 10-1 to 10-7 in FIG. 11) are arranged in a region corresponding to the bent portion 104 of the L-shaped pipe 102. In this case, it is preferable to arrange the wall thickness detectors 10 in a manner that minimizes the gaps formed between adjacent wall thickness detectors 10. This makes it possible to eliminate any region where a reduction in wall thickness is not detected. Although seven wall thickness detectors 10 are arranged in a region in FIG. 12, the number of wall thickness detectors 10 can be appropriately changed depending on the size and shape of the L-shaped pipe 102.

[0056] With a plurality of wall thickness detectors 10 arranged around the bent portion 104 of the L-shaped pipe 102, the wall thickness of the L-shaped pipe 102 can be detected using the wall thickness detection method described above during operation of the plant facility 100, thereby making it possible to monitor changes over time in the wall thickness of the L-shaped pipe 102. In this case, once one end of the wall thickness detector 10 is attached to the L-shaped pipe 102, the wall thickness detector 10 is maintained attached to the L-shaped pipe 102 until, for example, a reduction in the wall thickness of the L-shaped pipe 102 is detected.

[0057] 13 is a diagram showing the configuration of a wall thickness monitoring system 150 including a plurality of wall thickness detectors 10. The wall thickness monitoring system 150 includes n wall thickness detectors 10-1 to 10-n arranged, for example, at a bent portion 104 of an L-shaped pipe 102, a communication network NW connecting each of the wall thickness detectors (10-1 to 10-n) and a management device 30, and the management device 30.

[0058] In such a wall thickness monitoring system 150, when the output voltage of each Hall element 18 output from each wall thickness detector (10-1 to 10-n) is measured, the measurement value is transmitted as measurement data to the management device 30. An identification number is assigned to each wall thickness detector (10-1 to 10-n) in advance, and measurement data including the identification number is transmitted. Each wall thickness detector (10-1 to 10-n) and the management device 30 are connected via a communication network NW, so that data can be transmitted and received even if each wall thickness detector (10-1 to 10-n) and the management device 30 are located relatively far apart.

[0059] When the management device 30 receives the measurement data from the wall thickness detection device 10, the management device 30 stores the measurement data in a storage device and determines the presence or absence of wall thinning and its location based on the measurement data. When the management device 30 determines that wall thinning has occurred, the management device 30 may be configured to issue a warning to prompt replacement or repair of the L-shaped pipe 102.

[0060] In addition, each wall thickness detection device (10-1 to 10-n) attached to the L-shaped pipe 102 constantly monitors the change in wall thickness over time while the plant equipment 100 is in operation, but in order to reduce power consumption, the wall thickness may be detected at a predetermined time interval.

[0061] As described above, a torus-shaped magnetic flux is generated including a part of the object 8 to be measured in its path, and the leakage magnetic flux Φ leaking from the object 8 to be measured when the thickness of the object 8 to be measured is reduced is detected by the Hall element 18, which is a magnetic detection element, thereby making it possible to detect the portion where the thickness of the object 8 to be measured is reduced. Furthermore, the magnetic circuit 17 generates magnetic flux in a torus shape, which makes the magnetic flux uniform, and it is possible to detect the leakage magnetic flux Φ leaking from the object 8 to be measured regardless of the relative position between the thickness detection device 10 and the portion where the thickness is reduced, so that the portion where the thickness is reduced can be suitably detected.

[0062] In this embodiment, a torus-shaped magnetic flux can be generated by the first magnet 14 and the second magnet 16 arranged to surround the outer edge of the first magnet 14. Furthermore, by connecting the first magnet 14 and the second magnet 16 with the yoke 12, a strong magnetic field can be generated by the yoke 12 without using a magnet with a complex shape.

[0063] In addition, in this embodiment, when generating a torus-shaped magnetic flux, power consumption can be reduced by using permanent magnets as the first magnet 14 and the second magnet 16. Also, the device can be configured with permanent magnets of relatively simple shapes, such as rod-shaped magnets and ring-shaped magnets. Furthermore, by forming the second magnet 16 in a ring shape, a uniform magnetic flux can be generated at any position in the toroidal direction.

[0064] In addition, in this embodiment, by using the above-mentioned wall thickness detection method while the plant facility 100 is in operation, it is possible to constantly monitor the change over time in the wall thickness of the L-shaped pipe 102. In particular, by disposing the wall thickness detection device 10 on the surface of the L-shaped pipe 102, which is the part of the pipe where thinning is most likely to occur, the wall thickness detection device 10 can be used efficiently. In addition, by spreading the wall thickness detection devices 10 all over the place to reduce the gaps formed between adjacent wall thickness detection devices 10, it is possible to detect any part where the wall thickness is thinning without fail.

[0065] [Variations] FIG. 14 is a perspective view of a thickness detector 200 having a hexagonal peripheral edge (outer edge) in another embodiment of the thickness detector 10. The thickness detector 200 includes an umbrella-shaped yoke 202 having a hexagonal peripheral edge, a prism-shaped first magnet 204 (hereinafter, the first magnet 204) having a hexagonal peripheral edge, and an annular second magnet 206 (hereinafter, the second magnet 206) having a hexagonal peripheral edge. The hexagonal shapes of the yoke 202, the first magnet 204, and the second magnet 206 are all formed to be similar to each other, and preferably are formed to be regular hexagonal. Although omitted in FIG. 14, six Hall elements 18 (see FIG. 15) corresponding to the shapes of the peripheral edges are arranged in a circumferential direction between the first magnet 204 and the second magnet 206.

[0066] One end of the first magnet 204 in the longitudinal direction is connected to the center of the yoke 202. The second magnet 206 is connected to the hexagonal peripheral portion of the yoke 202. Both the first magnet 204 and the second magnet 206 are made of permanent magnets. As in the thickness detector 200, the outer shape of the second magnet 206 is formed in a hexagonal shape, so that when a plurality of thickness detectors 200 are laid out in a predetermined area, the gap between adjacent thickness detectors 200 can be eliminated compared to the thickness detector 10 having a circular outer shape. In addition, the periphery of the yoke 202 is also formed in a hexagonal shape, so that the yokes 202 of the adjacent thickness detectors 200 are prevented from interfering with each other. Furthermore, the periphery of the first magnet 204 is also formed in a hexagonal shape, so that a uniformly distributed torus-shaped magnetic flux can be generated.

[0067] 15 shows seven wall thickness detectors (200-1 to 200-7) arranged in a predetermined area of ​​the measurement object 8 (e.g., L-shaped pipe 102). The outer shape of each wall thickness detector (200-1 to 200-7) is formed in a hexagon, so that the wall thickness detectors (200-1 to 200-7) are arranged closely together with no gaps. As a result, the wall thickness detectors 200 are arranged efficiently, and the areas of the measurement object 8 where the wall thickness is thin can be detected without missing any.

[0068] 16 is a cross-sectional view (poloidal cross-sectional view) of a wall thickness detector 210 in which a plurality of Wiegand elements 212 are used instead of the plurality of Hall elements 18 used in the wall thickness detector 10, cut in the circumferential direction (colloidal direction) at the position where the Wiegand elements 212 are arranged. In the wall thickness detector 210, eight Wiegand elements 212 are arranged in the circumferential direction. The wall thickness detector 210 is the same as the wall thickness detector 10 described above except for the Wiegand elements 212, so the same reference numerals are used and the description thereof is omitted. In this embodiment, a magnetic circuit 17 is formed that generates a torus-shaped magnetic flux including the yoke 12, the first magnet 14, the second magnet 16, and a part of the measurement object 8.

[0069] The Wiegand element 212 is an example of an energy harvesting element, and is configured by winding a conductor around a Wiegand wire. Specifically, the Wiegand element 212 is a so-called cored coil that includes a core member 214 that serves as an axis and a coil 216 in which a long conductor is wound around the core member 214.

[0070] The core member 214 is a cylindrical (rod-shaped, wire-shaped) member (Wiegand wire) made of iron-cobalt-vanadium alloy (FeCoV) processed to have a hard magnetic outer shell and a soft magnetic inner shell. In such a Wiegand element 212, as shown in FIG. 17, when the external magnetic field (applied magnetic field) H is increased from 0 and the external magnetic field H becomes a predetermined external magnetic field +H, a so-called large Barkhausen jump occurs. At this time, the magnetization M penetrating the coil 216 increases like a jump, so that an induced electromotive force occurs between the terminals of the coil 216. Therefore, the generation of the external magnetic field +H can be detected by detecting the induced electromotive force generated in the Wiegand element 212 with the controller 20. In addition, the Wiegand element 212 does not generate a large Barkhausen jump in the process of increasing the external magnetic field H to the external magnetic field +H0 after generating the large Barkhausen jump and then returning it to 0. On the other hand, when the Wiegand element 212 further reduces the external magnetic field H from 0 and the external magnetic field H reaches a predetermined external magnetic field -H, a large Barkhausen jump occurs again. After the Wiegand element 212 generates the large Barkhausen jump, the Wiegand element 212 does not generate a large Barkhausen jump in the process of reducing the external magnetic field H to the external magnetic field -H0 and then returning it to 0. The Wiegand element 212 has such magnetic hysteresis characteristics.

[0071] This Wiegand element 212 is arranged so that when the magnetic flux formed by the magnetic circuit 17 leaks due to thinning of the object to be measured 8, the leakage magnetic flux Φ is applied in a desired detection direction as an external magnetic field H. For example, when detecting the leakage magnetic flux Φ due to thinning in a detection direction substantially parallel to the surface of the object to be measured 8, the Wiegand element 212 is arranged so that the longitudinal direction of the core member 214 (the axial direction of the coil 216) is substantially parallel to the surface of the object to be measured 8.

[0072] Since the Wiegand element 212 has the above-mentioned characteristics, it is designed so that the predetermined external magnetic field +H (or external magnetic field −H) coincides with the magnitude of the leakage magnetic flux Φ that occurs during thinning.

[0073] 18 shows an example of a processing circuit 218 that processes the output of the Wiegand element 212 when the Wiegand element 212 is used, and in this embodiment, a notification unit is provided that notifies the outside in response to detection of leakage magnetic flux Φ by the Wiegand element 212. Although only one Wiegand element 212 is shown in the processing circuit 218 of FIG. 18, the processing circuit 218 is actually configured to include a plurality of Wiegand elements 212. The notification unit notifies the outside of the detection by the energy generated by the Wiegand element 212. The notification unit operates by the electromotive force generated in the Wiegand element 212 by the leakage magnetic flux Φ generated during thinning.

[0074] As shown in FIG. 18, the notification unit includes a full-wave rectifier circuit RH, a capacitor C, first to fourth resistor elements R1 to R4, a buzzer BU (notification mechanism), first and second transistor elements Tr1 and Tr2, and a battery BT. The full-wave rectifier circuit RH is connected to both terminals of the coil 216 of the Wiegand element 212, and full-wave rectifies the output of the Wiegand element 212. The capacitor C is connected between the output terminals of the full-wave rectifier circuit RH, and smoothes the output of the full-wave rectifier circuit RH. The first resistor element R1 is connected in parallel to the capacitor C. The second resistor element R2 has one terminal connected to the connection point between the capacitor C and the first resistor element R1, and the other terminal connected to the base terminal of the second NPN transistor element Tr2. The emitter terminal of the second transistor element Tr2 is connected to the buzzer BU and is grounded via the buzzer BU.

[0075] The negative terminal of the battery BT is grounded, and the positive terminal is connected to the emitter terminal of a PNP-type first transistor element Tr1 via a fourth resistor element R4. The base terminal of the first transistor element Tr1 is connected to the emitter terminal of the first transistor element Tr1 via a third resistor element R3, and is also connected to the collector terminal of the first transistor element Tr1. The collector terminal of the first transistor element Tr1 is connected to a connection point between the second resistor element R2 and the base terminal of the second transistor element Tr2. The first transistor element Tr1, the second transistor element Tr2, and the third resistor element R3 constitute a so-called latch circuit RC.

[0076] In the notification section of the processing circuit 218 configured as above, the electrical signal (pulse potential signal) output from the Wiegand element 212 is rectified by the full-wave rectifier circuit RH, smoothed by the capacitor C, and input to the base terminal of the second transistor element Tr2 via the second resistor element R2, turning on the second transistor element Tr2. When the second transistor element Tr2 is turned on, the first transistor element Tr1 is turned on, the latch circuit RC is latched on, power is supplied from the battery BT to the buzzer BU via the latch circuit RC, and the buzzer sounds.

[0077] FIG. 19 is a flowchart for explaining a method for detecting thickness when a Wiegand element 212 is used instead of the Hall element 18.

[0078] First, the thickness detector 10 is placed on the surface of the portion of the object 8 whose thickness is to be grasped (step ST11). Next, after the Wiegand elements 212 are put into an operation standby state (step ST12), it is determined whether an electric signal (pulse potential signal) has been received from each Wiegand element 212 (step ST13). The operation of step ST13 is repeatedly executed until an electric signal is received. When the electric signal is received, a latch circuit RC mounted on the notification mechanism (buzzer BU, etc.) of each Wiegand element 212 is turned ON, and the notification mechanism starts to operate (step ST14). Next, the Wiegand element 212 that has operated is identified based on the acquired electric signal, and the position where the thinning has occurred is determined (ST15).

[0079] As described above, even when the Wiegand element 212 is used instead of the Hall element 18, the reduction in thickness of the object to be measured 8 can be detected by the controller 20 detecting the induced electromotive force generated in the Wiegand element 212 by the leakage magnetic flux Φ associated with the reduction in thickness of the object to be measured 8.

[0080] In the above embodiment, the second magnets 16, 206 are formed so as to surround the first magnets 14, 204, but the second magnets 16, 206 are not necessarily limited to a form in which they surround the entire circumferential area. That is, the second magnets 16, 206 may be divided into a plurality of areas in the circumferential direction, and gaps may be formed between adjacent areas. In this case, the plurality of magnetic circuits 17 are formed so as to be aligned in the toroidal direction, but even in this case, it is sufficient that the magnetic circuits generate a torus-shaped magnetic flux as a whole.

[0081] In addition, in the above embodiment, the yoke 12 and the first magnet 14 are formed so as to be solid in the center, but the yoke 12 and the first magnet 14 may also be formed so as to be hollow in the center, with a space formed therein.

[0082] In the above embodiment, the first magnets 14, 204 and the second magnets 16, 206 are made of permanent magnets, but may be made of electromagnets. Also, the first magnets 14, 204 and the second magnets 16, 206 may be made of a magnetic body connected to a magnet.

[0083] In the above embodiment, the second magnet 16 constituting the wall thickness detector 10 may be composed of a plurality of magnets formed in an arc shape. Alternatively, the second magnet 16 may be formed in an annular shape as a whole by arranging a plurality of bar magnets in an annular shape.

[0084] In the above embodiment, the second magnet 206 of the wall thickness detector 200 may be configured with six magnets corresponding to each side. For example, the magnets corresponding to each side may be configured with multiple bar magnets arranged adjacent to each other with no gaps between them. Alternatively, the second magnet 206 may be divided into six regions on each side, and the magnets in each region may be configured with one or more magnets.

[0085] In the above embodiment, the magnetic field generating source 15 is composed of three components, the yoke 12, the first magnet 14, and the second magnet 16. However, as long as one of a pair of magnetic poles is configured to surround the other magnetic pole, various configurations are possible. For example, the magnetic field generating source 15 may be composed of a single magnet having the same shape as the combination of the above three components, or may be composed of two components, the first magnet and the yoke. In the latter case, the yoke has a shape that also includes the second magnet.

[0086] In the above embodiment, the wall thickness detector 10, 200 includes eight or six Hall elements 18, but the number of Hall elements 18 is not limited to eight or six and may be changed as appropriate, for example, to four. Similarly, the number of Wiegand elements 212 included in the wall thickness detector 210 may be changed as appropriate.

[0087] In the above embodiment, the bent portion 104 of the L-shaped pipe 102 is exemplified as a portion where the wall thickness is likely to become thin, but the portion where the wall thickness is likely to become thin is not necessarily limited to this. For example, a pipe that changes into a bellows shape is also likely to become thin. In other words, the present invention is not limited to the L-shaped pipe 102, and can be used as appropriate for any portion where there is a risk of wall thinning.

[0088] In the above embodiment, the wall thickness detection device 10 can be removed each time the wall thickness of the measurement object 8 and the L-shaped pipe 102 is inspected, and used in another location, and can be used as a mobile inspection device. The wall thickness detection device 10 and the wall thickness detection method using the same can be used not only to detect thinning, but also to inspect the distribution of wall thickness. For example, the device can be used to inspect the distribution of wall thickness caused by manufacturing variations.

[0089] In the above embodiment, the yoke 12 of the wall thickness detector 10 has a circular periphery, and the yoke 202 of the wall thickness detector 200 has a hexagonal periphery, but the shape of the periphery of the yoke is not necessarily limited to this. For example, the periphery of the yoke may be triangular, rectangular, or other polygonal, or may be elliptical. That is, the yoke may be formed as a whole in an umbrella shape, and may be freely changed as long as it can generate a torus-shaped magnetic flux. Similarly, the shape (outer shape) of the periphery of the second magnet may be freely changed within a range in which a torus-shaped magnetic flux can be generated.

[0090] In the above embodiment, the management device 30 judges that a wall-thickness reduction has occurred when the voltage output from each Hall element 18 exceeds a predetermined management value, but the judgment of wall-thickness reduction is not limited to this. For example, the management device 30 may store the voltage output from each Hall element 18 immediately after the installation of the wall-thickness detection device 10, 200 as an initial voltage, and estimate the part where the wall-thickness is thin based on the result of comparing the output voltage with the initial voltage. In this case, it is judged that the wall-thickness is thin when the output voltage is higher than the initial voltage. Also, for example, each output voltage (Vout_1 to Vout_8) output from each Hall element 18 of the same wall-thickness detection device 10 may be compared, and the part where the wall-thickness is thin may be estimated from the result. In this case, it is judged that the wall-thickness is thin at the position corresponding to the Hall element 18 with the larger output voltage. Also, for example, the above-mentioned methods may be combined.

[0091] In addition, the management device 30 may store in advance the correspondence between the voltage output from each Hall element 18 and the thickness of the object to be measured 8, and use this correspondence to estimate the thickness at the position corresponding to each Hall element 18 from the output voltage of each Hall element 18 to estimate the distribution of thickness, or may detect the occurrence of thinning based on the result of comparing the estimated thickness with a management value.

[0092] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments with reference to the drawings in the above description, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0093] 8: Measurement object 10: Wall thickness detector 12: York 14: First magnet (other magnetic pole) 15: Magnetic field source 16: Second magnet (one pole) 17: Magnetic circuit 18: Hall element (magnetic detection element) 100: Plant equipment (equipment) 102: L-shaped piping (piping) 200: Wall thickness detector 202: York 204: First magnet (other magnetic pole) 206: Second magnet (one pole) 210: Wall thickness detector 212: Wiegand element (magnetic detection element)

Claims

1. A method for detecting a thickness of an object to be measured, comprising the steps of: A torus-shaped magnetic circuit is formed, which includes a part of the object to be measured in its path and generates magnetic flux in a poloidal direction, and a plurality of magnetic detection elements are arranged in the toroidal direction on the object to be measured inside a poloidal cross section cut by a plane passing through the center line of the torus within the magnetic circuit, and the magnetic flux leaking from the object to be measured is detected by the magnetic detection elements. A method for detecting a thickness.

2. A plurality of the torus-shaped magnetic circuits are formed along the surface of the object to be measured, and a plurality of the magnetic detection elements are arranged in a toroidal direction for each of the torus-shaped magnetic circuits. The method for detecting a wall thickness according to claim 1 .

3. A magnetic field generating source configured such that one of a pair of magnetic poles surrounds an outer edge of the other magnetic pole; a plurality of magnetic detection elements disposed between the one magnetic pole and the other magnetic pole; A wall thickness detection device.

4. A first magnet constituting the other magnetic pole; a second magnet that constitutes the one magnetic pole, is disposed so as to surround the outer edge of the first magnet, and has a magnetic pole oriented in an opposite direction to that of the first magnet; a yoke connecting the first magnet and the second magnet; a plurality of the magnetic detection elements disposed between the first magnet and the second magnet; 4. The wall thickness detection device according to claim 3.

5. The yoke is formed in an umbrella shape, The first magnet is composed of a rod-shaped permanent magnet, the second magnet is an annular permanent magnet, One end of the first magnet in a longitudinal direction is connected to the center of the yoke, One end of the second magnet is connected to the periphery of the yoke.

5. The wall thickness detection device according to claim 4.

6. The second magnet has a hexagonal periphery.

6. The wall thickness detection device according to claim 5.

7. a torus-shaped magnetic flux is generated with the first magnet and the second magnet in contact with the object to be measured, the torus-shaped magnetic flux including the object to be measured in a path of the magnetic flux; The magnetic flux leaking from the object to be measured is detected by the magnetic detection element, thereby detecting a portion of the object to be measured where the thickness is thin.

7. The wall thickness detector according to claim 4, wherein the wall thickness detector is a device for detecting a wall thickness of a wall.

8. During operation of a given facility, the thickness of a measurement object constituting the given facility is monitored by using the thickness detection method according to claim 1 or 2. A method for monitoring thickness.

9. The thickness detector according to any one of claims 3 to 6 is disposed on a surface of a measurement object that constitutes a part of a predetermined facility, and the thickness of the measurement object is monitored during operation of the facility. A method for monitoring thickness.

10. 10. The method for monitoring thickness according to claim 9, further comprising arranging a plurality of said thickness detection devices in a line on the surface of said object to be measured, and monitoring the thickness of said object to be measured.

11. the measurement object is a piping of the facility, The wall thickness detector is disposed on the surface of the bent portion of the pipe.

10. The method of claim 9, wherein the thickness of the wall is monitored.

12. 4. The wall thickness detection device according to claim 3, wherein the magnetic detection element is a Hall element or a Wiegand element.

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