JP2010048624A - Low-frequency electromagnetic induction type defect measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion defect measuring apparatus which utilizes a low-frequency electromagnetic induction method, scanning inspection modules on the outer surface of a to-be-inspected object, and quantitatively and accurately measuring and evaluating corrosion defects, especially the magnitude and the depth of the corrosion defect. <P>SOLUTION: The corrosion defect measuring apparatus is provided with a running element 10 for scanning the outer surface of a structure H, and the running element 10 is provided with two running bodies 11, having wheels with magnet rings, and a support frame 20 for connecting the running bodies 11. A plurality of the inspection modules 1 for inspecting the defect in the structure, by using a low-frequency electromagnetic induction, are linked circularly to each other and are connected to the support frame 20. By making the running bodies 11 run in a state where they are attached to the outer surface of the structure H, defect in the structure H is measured by the inspection modules 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a low-frequency electromagnetic induction type defect measuring apparatus for measuring defects of a structure made of a magnetic material, in particular, corrosion defects of piping, by a low-frequency electromagnetic induction method.

  When detecting and evaluating defects in a structure made of a ferromagnetic material, it is often difficult to directly measure the inside of the structure, or even if possible, it takes a lot of labor and cost. Therefore, an ultrasonic flaw detection method is generally used as a method for detecting and evaluating defects inside the structure by measurement from the outer surface of the structure, and is present, for example, in the inside or the surface of steel. A defect is known in which a plurality of ultrasonic probes are juxtaposed to perform multi-channel ultrasonic flaw detection (Patent Document 1). However, the ultrasonic flaw detection method as shown in Patent Document 1 requires a ground treatment to remove foreign matter such as rust and dust on the surface to which the probe is applied, and in some cases, the coating film, and it takes a lot of trouble in measurement. There is a problem that it takes. In addition, a contact medium is necessary between the object to be measured and the measurement location is pinpointed (in Patent Document 1, this problem is addressed by arranging a plurality of ultrasonic probes in parallel. Etc.).

  On the other hand, a structure defect measurement technique using an electromagnetic induction method has been proposed (Patent Documents 2 and 3). In Patent Document 2, the inspection object is magnetized, the magnetic flux leaking from the internal defect portion of the inspection object to the surface is detected by the magnetic field detector, and the output signal of the magnetic field detector is expressed by the magnetization force received by the inspection object. Branch after compensation, one of them is differentiated to make a steep waveform, the other is integrated to remove low frequency noise components, and then the differentiated signal and the integrated signal are synthesized, and the synthesized signal waveform is The defect inspection is evaluated.

Further, in Patent Document 3, the structure is inspected for corrosion defects or the like by a low-frequency electromagnetic induction method, and is made of a ferromagnetic material in order to detect a corrosion thinning portion and calculate a remaining thickness. By scanning the outer surface of the object to be inspected, the detection data is collected by the magnetic flux detection coil, multiplied by the signal used as the phase detection processing reference, filtered, and the coordinates of the vector coordinates obtained from the coordinate conversion destination Conversion, that is, rotation of the coordinate axis is performed, a thinned portion is detected, the defect diameter is estimated, and the defect diameter is estimated from the attenuation method (tilt) between the channels.
Japanese Patent No. 3228132 Japanese Unexamined Patent Publication No. 07-072122 JP 2006-208312 A

  The methods disclosed in Patent Documents 2 and 3 do not need to remove foreign matter such as rust and dust on the surface to which the probe (inspection module) is applied, or the coating film, unlike the ultrasonic flaw detection method. It is excellent in that it can measure and evaluate the size and depth of corrosion defects.

  However, in particular, Patent Documents 2 and 3 disclose measurement flaw detection techniques using magnetic field leakage by electromagnetic induction, but these techniques have been applied to things such as piping installed in a plant. Problems arise. That is, when a plurality of inspection modules are arranged in a ring shape around the entire outer surface of the pipe and scanned in the axial direction of the pipe, the protrusions and connection portions provided on the outer surface of the pipe Cannot be inspected. For this reason, there is an inconvenience that it is necessary to inspect pipes for inspection.

  On the other hand, even if a plurality of inspection modules are arranged in a partial arc shape and a partial inspection is attempted, a technique for specifically attaching the inspection module to the outer periphery of the pipe and a technique for scanning are not established and embodied. It is in a situation that is not.

  The present invention has been made in view of the above circumstances, and by utilizing the low frequency electromagnetic induction method, the inspection module is scanned over the outer surface of the structure (inspection object), and the size of the corrosion defect, particularly the corrosion defect is determined. The object is to provide a corrosion defect measuring apparatus capable of measuring and evaluating the depth quantitatively and with high accuracy. In particular, a measuring device capable of inspecting the outer surface of an object to be inspected by scanning a plurality of inspection modules partially in an arc shape on the outer periphery of the object to be inspected and scanning the inspection module in the axial direction of the object to be inspected Is to provide.

  In order to achieve the above object, in claim 1 of the present invention, there is provided a low frequency electromagnetic induction type defect measuring apparatus for measuring defects of a structure made of a magnetic material, wherein the outer surface of the structure is A traveling body that scans, and the traveling body includes two traveling body main bodies having wheels with magnet wheels, and a support frame that connects the traveling body main bodies to each other. A plurality of inspection modules for inspecting defects are connected in a substantially arc shape and connected to the support frame.

  According to a second aspect of the present invention, in the low frequency electromagnetic induction type defect measuring apparatus according to the first aspect, the support frame is connected to the traveling body main body via an angle adjusting portion.

  A third aspect of the present invention is the low frequency electromagnetic induction type defect measuring apparatus according to the first or second aspect, wherein the inspection module is connected to the support frame by a spring member.

  According to a fourth aspect of the present invention, in the low-frequency electromagnetic induction type defect measuring apparatus according to any one of the first to third aspects, a motor is attached to each traveling body and is connected to a controller that controls each motor independently. It is characterized by.

A fifth aspect of the present invention relates to the low frequency electromagnetic induction type defect measuring device according to any one of the first to fourth aspects,
A structure made of a magnetic material is a cylindrical object to be inspected, the plurality of inspection modules are connected to each other in an arc shape corresponding to the outer diameter of the object to be inspected, and inspection modules at both ends are provided. It is connected to a support frame.

  According to the first aspect of the present invention, flaw detection can be performed with a small clearance even in a place where pipes which are structurally inspected objects are densely packed. There is no need to remove foreign matter such as rust and dust on the surface to which the inspection module is applied, or the coating, and rolled inclusions and laminations detected in parallel with the plate thickness can be ignored as noise. There is no fear of misidentification.

  According to the second aspect of the present invention, the traveling body can be reliably grounded in the vertical direction with respect to the outer surface of the structure, and can be stably traveled in this state, so that the defect can be accurately measured with a compact device. .

  According to the third aspect, since the inspection module is forced to come in contact with the outer surface, the structure can be reliably inspected for defects.

  According to the fourth aspect, since flaw detection can be performed by remote operation, installation of a scaffold or the like can be minimized. The traveling body can be reliably traveled on the outer surface of the inspection object with high accuracy, and the speed and direction of the traveling body can be easily controlled.

  According to the fifth aspect of the present invention, flaw detection can be performed with a small clearance even in a place where pipes which are structurally inspected objects are densely packed. Further, since the arc shape of the inspection module can be adjusted according to the outer diameter of the cylindrical tube, the adjustment is easy.

(Embodiment 1)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of an inspection module. In FIG. 1, an inspection module 1 for measuring an internal defect K of an inspection object H includes a magnet body 2 having a substantially U-shaped cross section having a magnetic path for magnetizing the inspection object H, and a leakage magnetic flux leaking from the magnet body 2. Is provided, and a detection coil 4 is provided in the magnetic shield 3. Reference numeral 5 denotes a magnetizing coil for magnetizing the magnet 2. As shown in FIG. 2, two rollers 6 are provided on the front and rear sides of the magnet 2.

  Four detection coils 4 are provided, and two channels are provided to output two as a set. Sixteen inspection modules 1 are provided side by side, and the number of inspection modules 1 is 32 by 16 × 2 channels.

  As shown in FIGS. 2 to 3, the inspection module 1 is arranged in a substantially arc shape by connecting 16 inspection modules 1 with a connecting member 7. As shown in FIG. 3, by preparing a connecting member 7 that matches the size (diameter) of the inspection object H and connecting the inspection module 1, as shown in FIGS. 3A and 3B. In addition, a plurality of inspection modules 1 can be arranged in a predetermined arc state in accordance with the diameter of the inspection object H. In this embodiment, the connecting member 7 is replaced and the arcuate diameter formed by the plurality of inspection modules 1 is changed, but by providing a plurality of holes in the connecting member or by providing a long hole, etc. The diameter may be changed without replacing the connecting member, or the diameter may be changed by other means.

  Based on FIGS. 4-6, a detailed structure is demonstrated further. A scanning body 10 supports the inspection module 1. The scanning body 10 includes two traveling main bodies 11 that scan in the axial direction of the inspection object H and an arcuate support frame 20 that connects the traveling main bodies 11. The traveling body 11 includes a frame body 12 having a substantially U-shaped cross section. A wheel 13 having magnet wheels 14 on both sides is rotatably supported in the frame body 12. Since both the magnet wheels 14 are strongly attracted to the outer surface of the inspection object H, the wheel 13 is accurately grounded perpendicularly to the inspection object H. In particular, since both the traveling main bodies are connected to the support frame 20 by the angle adjusting unit 30 described in detail later, it is possible to reliably stand upright.

  A motor 15 is attached to the outside of the frame body 12. A reduction mechanism 16 is connected to the motor 15, a pulley 17 is connected to the reduction mechanism 16, a pulley 19 is connected to the wheel 13, and a timing belt is stretched between the pulley 17 and the pulley 19. The rotational force of the motor 15 is transmitted to the wheel 13 through the speed reduction mechanism 16, the pulley 17, the timing belt 18, and the pulley 19.

  The support frame 20 is formed of a rectangular frame so as to surround the inspection module 1 and is formed in an arc shape matching the diameter of the inspection object H. The short side 20 a of the support frame 20 is connected to the traveling main body 11 via the angle adjustment unit 30. The inspection module 1 on both sides is connected to the inner side surface of the short side 20a via the spring member 21, and the entire inspection module 1 is in contact with the outer surface of the inspection object H so as to pull the inspection module 1 on both sides to both sides. It is supposed to be strong in the direction to do. It should be noted that pulleys may be provided at several locations in the middle of the long sides 20b and 20b for guiding the long sides 20b and 20b in contact with the surface of the inspection object H. The spring member 21 is provided so as to pull the inspection modules 1 on both sides outward. However, the spring member 21 is not limited to the outer inspection module 1 and may be provided so as to pull other inspection modules 1. Moreover, it is good also as a connection member instead of a spring member. In addition, several types of support frames 20 are prepared according to the diameter of the non-inspection object H, and those corresponding to the diameter of the inspection object H are connected to the traveling body 11. The arcuate diameter of the support frame 20 may be changed by other methods. Further, the support frame 20 is more compact when formed in an arc shape, but it is only necessary that both the traveling main bodies 11 can stand vertically on the outer surface of the object to be inspected, and may have other shapes.

  The detailed structure of the angle adjusting unit 30 will be described with reference to FIGS. The angle adjustment unit 30 is configured as follows. An attachment member 33 is attached to a bracket 31 fixed to the frame 12 by a rotary shaft 32 so that the angle can be adjusted. The attachment member 33 is fixed to the short side 20 a of the support frame 20. A screw member 36 is provided through a long hole-like through hole 35 opened in an attachment piece 34 attached to the attachment member 33. The attachment piece 34 is sandwiched between a nut 41 and a washer 42 that are screwed into a male screw of the screw member 36. The tip of the screw member 36 is welded to the shaft member 37. The shaft member 37 is rotatably disposed in the bracket 31. When the nut 41 is loosened with a tool (not shown) and both nuts 41 are rotated in the direction of the arrow, the state shown in FIG. 7 is changed to the state shown in FIG. 8, and the angle between the bracket 31 and the mounting member 33 is changed. The angle of the bracket 31 and the attachment member 33 is changed by the angle adjustment unit 30, so that the traveling main body 11 has a degree of freedom of angle adjustment with respect to the support frame 20. On the other hand, the traveling body 11 can be surely set up vertically (radial direction) with respect to the inspection object H. In addition, since the shaft member 37 is rotatable and the through hole 35 of the attachment piece portion 34 is opened in a long hole shape, even when the angle between the bracket 31 and the attachment member 33 is changed, it is ensured. Positioned and held. In addition, the angle adjustment part 30 is not restricted to this structure, Another structure may be sufficient.

  FIG. 10 shows a connection state between one scanning body 10 and the controller 40. Although not shown, the other scanning body 10 is also connected to the controller 40. The controller 40 can control the movement of both scanning bodies 10. The motors 15 of the two scanning bodies 10 are connected to the controller 40 by wires 39, respectively. By operating an operation unit (not shown) provided in the controller 40, both the scanning bodies 10 can be controlled independently of each other, that is, switching between pre-rotation and post-rotation and speed change can be performed. It is possible to easily change the direction of both scanning bodies 10 or correct the direction. Although connected to the controller 40 by the wiring 39, it may be wireless.

  Further, in actual work, when the inspection module 1 and the scanning body 11 are erected on the lower side of the inspection object H and run, the damage is prevented when the inspection module 1 falls off the inspection object H and falls. In addition, mats are laid.

  Processing of data measured by the inspection module 1 will be described. When the outer surface of the inspection object H is scanned, as shown in FIG. 12, the PHASE (phase value) output and the amplitude value (AMP) output indicated by the Log function are output to each inspection module (in this embodiment, 16 inspections). Output for each module). FIG. 11 shows an image displayed by editing the measured output three-dimensionally. In FIG. 11, the defect portion is seen protruding like a mountain in the 3D image.

  In FIG. 12, each horizontal line indicates the running state of 16 detection modules 1. First, a peak value is obtained from a shaken state by PHASE (phase value). In this FIG. 12, it is 12.64. Next, how many channels of the PHASE are shaken is obtained by an amplitude value (AMP) indicated by a Log function. Judgment is given that the peak value is more than half of the peak value. In this FIG. 12, since it is determined as a channel that has shaken more than half (6.32) of the peak value, there are nine.

  The obtained PHASE value and the number of shakes (9) are applied to the calibration curve shown in FIG. 13 to evaluate defects. Since PHASE is 12.64 and the number of shakes is nine, in FIG. That is, it is on the curve of 60% thinning. Therefore, this defect is evaluated as 60% thinning. That is, it is determined that a defect having a depth of 60% exists.

  In addition, if the number of shakes is 10, it is evaluated as 55% thinning because it is between 60% thinning and 45% thinning and is slightly closer to 60% thinning. In this way, each defect is evaluated and all defects are evaluated. In addition, each curve of FIG. 13 shows the calibration curve calculated | required by measuring with this defect measuring device what the magnitude | size and depth of the defect were understood beforehand.

  Since the corrosion defect signal is judged from the two output data of the PHASE output and the amplitude value (AMP) output indicated by the Log function, the welding trace and the lift-off signal (indicating the case where the sensor of the detection module is separated from the outer surface of the object to be detected) Signal) and the like can be clearly distinguished. It is two output data of the PHASE output and the amplitude value (AMP) output indicated by the Log function. For example, if the amplitude value (AMP) output indicated by the Log function is significantly larger than the fluctuation of the PHASE output, welding is performed. If the amplitude value (AMP) output indicated by the Log function is negative, the amplitude indicated by the PHASE output and the Log function, such as a lift-off signal, is the trace. The combination of the two output data of the value (AMP) output, except for the combination pattern of the output in the case of the corrosion defect, is judged as noise so that the corrosion defect and noise can be clearly distinguished. It has become. In this way, in the present invention, the defect depth can be read by normalizing with the spread of the defect in order to obtain the depth information from the PHASE output signal proportional to the defect volume.

  In addition, according to the present invention, flaw detection can be performed with a small clearance even in a place where pipes which are structurally inspected objects are densely packed. Further, since flaw detection can be performed by remote control, installation of a scaffold can be minimized. It is not necessary to remove foreign matter such as rust and dust on the surface to which the inspection module is applied or the coating film. Rolled inclusions and laminations detected in parallel with the plate thickness can be ignored as noise, so there is no possibility of misidentifying it as a serious defect.

  Although the case where the internal defect of the magnetic material is measured has been described in the above embodiment, it is needless to say that the present invention can be applied to defect flaws generated on the surface and the inner surface of the magnetic material. It can also be applied to pipes that measure defects such as corrosion, especially when it is applied to pipe defects that are difficult to remove and require extensive work, such as pipes that are installed on a large scale such as a plant. preferable. As piping, it is suitable for measuring corrosion defects such as large-diameter pipes, spiral welded pipes, horizontal pipes, and vertical pipes.

The principle figure of the low frequency electromagnetic induction method concerning Embodiment 1 of this invention is shown. It is a perspective view which shows the outline at the time of connecting the inspection module concerning Embodiment 1 continuously. FIG. 3A is a cross-sectional view for explaining that the inspection module according to the first embodiment is attached in a substantially arc shape according to the outer diameter of the object to be inspected, and FIG. 3A is a large diameter and FIG. 3B is a small diameter. Indicates. It is sectional drawing which shows the state which has arrange | positioned the test | inspection module and traveling body of the defect measuring device concerning Embodiment 1 on the lower outer surface of large diameter piping. The top view of the defect measuring apparatus of FIG. 5 is shown. The partial enlarged view of the traveling body of FIG. 5 is shown. FIG. 6 is a partial diagram illustrating an operation state of an angle adjustment unit according to the first embodiment. FIG. 8 is a partial diagram illustrating an operation state different from FIG. 7. FIG. 9 is a partially enlarged view of FIG. 8. It is explanatory drawing explaining the state which operates a traveling body with a controller. An image obtained by editing the measured data in 3D is shown. The display screen of the measured data is shown. It is a calibration curve which shows the relationship between a phase value and the number touched.

Explanation of symbols

H Inspected object K Defect 1 Inspection module 6 Roller 7 Connecting member 10 Scanning body 11 Traveling body 13 Wheel 14 Magnet wheel 15 Motor 20 Support frame 21 Spring member 30 Angle adjusting unit 39 Wiring 40 Controller

Claims (5)

A low frequency electromagnetic induction type defect measuring device for measuring defects in a structure made of a magnetic material,
A traveling body that scans the outer surface of the structure,
The traveling body comprises two traveling body main bodies having wheels with magnet wheels, and a support frame for connecting the traveling body main bodies,
A low frequency electromagnetic induction type defect measuring apparatus, wherein a plurality of inspection modules for inspecting a defect of a structure by low frequency electromagnetic induction are connected in a substantially arc shape and connected to the support frame. . In the low frequency electromagnetic induction type defect measuring device according to claim 1,
A low-frequency electromagnetic induction type defect measuring apparatus, wherein the support frame is connected to the traveling body main body via an angle adjusting unit. In the low frequency electromagnetic induction type defect measuring apparatus according to claim 1 or 2,
The inspection module is connected to the support frame by a spring member, and a low frequency electromagnetic induction type defect measuring apparatus. The low frequency electromagnetic induction type defect measuring device according to any one of claims 1 to 3,
A low-frequency electromagnetic induction type defect measuring apparatus, wherein a motor is attached to each traveling body and connected to a controller that controls each motor independently. In the low frequency electromagnetic induction type defect measuring device according to any one of claims 1 to 4,
A structure made of a magnetic material is a cylindrical object to be inspected, the plurality of inspection modules are connected to each other in an arc shape corresponding to the outer diameter of the object to be inspected, and inspection modules at both ends are provided. A low-frequency electromagnetic induction type defect measuring device characterized in that it is connected to a support frame.

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