JP2000121610A - Coat peeling part detector using ppm electromagnetic ultrasonic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating peeling part detector capable of detecting a peeling position of a resin coat applied on a steel pipe by use of a PPM(Periodic Permanent Magnet) electromagnetic ultrasonic transducer. SOLUTION: SH wave (transversal wave polarized in the direction parallel to the boundary surface) transmitted from a transmitting spiral coil 4a of a PPM electromagnetic ultrasonic transducer 2 is transmitted through a peeling part 1B caused in a coating 1A to be received by a receiving spiral coil 4b. In this case, the attenuation of SH wave in the coating 1A is smaller in the case where the peeling part 1B is caused than the case where there is no peeling part 1B so that at the time of receiving, the sound pressure becomes high. When SH wave is transmitted toward the circumferential direction of a tube body l and measured while the PPM electromagnetic ultrasonic transducer 2 is moved along the pipe axis, the position where the peeling part 1B is caused can be specified according to the relation to the pipe axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a peeling portion of a coating using a PPM electromagnetic ultrasonic transducer for detecting a peeling portion generated in a coating applied to a surface of a metal body.

[0002]

2. Description of the Related Art Generally, an electromagnetic ultrasonic flaw detector is used to detect a defect in a metal. The principle of operation of this electromagnetic ultrasonic flaw detector is that a magnet and a coil are placed on the metal surface, and an electric current flows through the coil, and the interaction between the eddy current and the magnetic field induced in the metal causes the Lorentz force to be generated by the sound source. As a result, ultrasonic waves can be generated in the metal. Reception of ultrasonic waves utilizes the opposite phenomenon. The electromagnetic ultrasonic flaw detector operating on such a principle can detect flaws in a non-contact manner with respect to a flaw-detected object, and is therefore used for a high-temperature material, a rough-surfaced one, a coated one and the like. Further, even when flaw detection is performed while moving the ultrasonic transducer with respect to the flaw detection target, wear does not occur, and supply of water or the like as a coupling agent is not required.

[0003]

In particular, a resin portion coated on the outer surface of a metal body is referred to as a coating, and a device for detecting a peeling state of the coating as it is in a buried state has been developed. Was not. Therefore, the applicants have proposed that PP
I decided to consider using an M (Periodic Permanent Magnet) electromagnetic ultrasonic transducer. This is achieved by disposing a magnet unit having a specific arrangement of magnets and a spiral coil on the lower surface of the magnet unit, and
An apparatus for generating a wave (a transverse wave polarized in a direction parallel to the boundary surface) and calculating the stress from the propagation speed of the SH wave is disclosed in, for example, US Pat. No. 4,522,071. In this PPM electromagnetic ultrasonic transducer, the magnet unit described above includes a plurality of permanent magnets such that S and N poles are alternately arranged in the vertical direction of the transducer perpendicular to the propagation direction of the generated SH wave. A pair of alternating magnetic field forming magnet rows provided side by side in the row are provided, and the pair of alternating magnetic field forming magnet rows are arranged so that the right and left transducers are orthogonal to both the SH wave propagation direction and the transducer vertical direction. 2 in the direction (transducer width direction)
They are arranged in rows. Also, in the left-right direction, the polarities of the magnets at the corresponding positions are reversed. Further, one axis of the spiral coil described above is positioned vertically corresponding to the intermediate position of the alternating magnetic field forming magnet row arranged in two rows. An object of the present invention is to use a PPM electromagnetic ultrasonic transducer capable of not only detecting the presence / absence of peeling of a coating covering but also evaluating a peeling state such as a peeling position using a PPM electromagnetic ultrasonic transducer. It is another object of the present invention to provide an apparatus for detecting a coating-coated peeling portion.

[0004]

[Means for Solving the Problems] [Structure 1] A characteristic structure according to the first invention is a PPM electromagnetic apparatus that excites and transmits ultrasonic waves into a metal body provided with a coating on the surface and receives the returned ultrasonic waves. An ultrasonic transducer and a peeling evaluation unit that evaluates the peeling state of the coating device based on the sound pressure of the received ultrasonic wave are provided. The operational effects are as follows. [Effect] In this configuration, an alternating magnetic field is generated by permanent magnets arranged so that S poles and N poles are alternately arranged.
Because PM electromagnetic ultrasonic transducer is adopted,
By appropriately selecting the length of two adjacent permanent magnets and the alternating current flowing through the coil, it is possible to efficiently send out an ultrasonic wave having a wavelength suitable for detecting a target peeled portion. This makes it possible to use an ultrasonic wave having a wavelength that propagates well in the metal body provided with the coating and has a wavelength that responds favorably to the peeling state of the target peeling section. The transmitted ultrasonic wave after passing through the peeling part area or the reflected ultrasonic wave that is transmitted and reflected by the peeling part area is returned ultrasonic wave in the reference state such as the absence of the peeling part. On the other hand, it can be expected that satisfactory peeled part information that the sound pressure becomes higher is inherent.

[Structure 2] The characteristic structure of the second invention is as follows.
In the characteristic configuration according to the first invention, the metal body provided with the coating device is a tubular body, and the PPM electromagnetic ultrasonic transducer transmits ultrasonic waves in a circumferential direction of the tubular body and transmits a supersonic wave having passed around the tubular body. It is to receive a sound wave, and its operation and effect are as follows. [Effects] In particular, if the object to be inspected is a tubular body, if it is configured to transmit ultrasonic waves from the PPM electromagnetic ultrasonic transducer in the circumferential direction of the tubular body and receive transmitted ultrasonic waves circling the tubular body, The transmission method can be performed with only one PPM electromagnetic ultrasonic transducer. Since the electromagnetic ultrasonic waves are transmitted and received without contact, the transmission method can be performed with high accuracy, and is a particularly recommended detection method. Also, the compact structure of the PPM electromagnetic ultrasonic transducer allows for the detection of delaminations from the inner circumference of small tubes.

[Structure 3] The characteristic structure according to the third invention is as follows.
In the characteristic configuration according to the first invention, the peeling evaluation unit includes:
If the sound pressure of the received ultrasonic wave is higher than the sound pressure of the ultrasonic wave in the reference state where the separation portion does not exist, it is determined that the separation portion exists, and the operation and effect are as follows. [Effects] Actually, as described later, in a tubular body provided with a coating on the surface of a metal tube as the object of the present application, a peeled portion exists compared to a case where no peeled portion exists. I understood that the sound pressure of the received ultrasonic wave was higher when I did. It is considered that such a difference in sound pressure is caused by the suppression of the movement attenuation of the ultrasonic wave due to the presence of the peeled portion. Therefore, it is possible to evaluate the presence / absence, position, and degree of peeling of the peeled part by the structure of the peeling evaluation part.

[0007] The characteristic structure of the fourth invention is the first invention to the first invention.
In a characteristic configuration according to a third aspect of the present invention, the PPM electromagnetic ultrasonic transducer includes a pair of alternating magnetic field forming magnet rows each including a plurality of permanent magnets whose polarities are inverted in the vertical direction alternately in each row; A magnet unit having a configuration in which the magnetic field forming magnet rows are arranged in two rows on the left and right sides with a phase different from each other by 180 degrees; The transmission spiral coil and the reception spiral coil are provided separately at a lower position of the magnet unit via a separation membrane to constitute a transmission / reception PPM electromagnetic ultrasonic transducer. The operation and effect are as follows. [Effects] In the transducer of this configuration,
Since the transmission spiral coil and the reception spiral coil are separated and independent, so-called transmission and reception can be performed using separate coils. As a result, even if transmission is performed with a large signal, this is not possible. The noise on the received signal can be avoided. Therefore, it is possible to effectively transmit an ultrasonic wave having a relatively large sound pressure level and to receive a transmitted wave caused by the ultrasonic wave by the receiving spiral coil alone, thereby reducing noise and having a relatively high sound pressure level. High information can be obtained. Therefore, the field of application of the inspection apparatus of the present application is expanded, and reliable inspection can be easily performed.

[0008]

FIG. 1 is a side view of an in-pipe traveling cart 10 equipped with a coating-coated-peeling detection device using a PPM electromagnetic ultrasonic transducer according to the present invention. A state in which the vehicle travels in the axial direction in the iron pipe 1 is shown. A front wheel 12 is provided in a front region of the vehicle body 11 extending in the axial direction, and a rear wheel 1 is provided in a rear region.
3 are arranged. A front wheel drive mechanism 14 is provided to drive the front wheels 12.
Is a front wheel traveling motor 14a and the front wheel traveling motor 14
and a transmission mechanism 14b for transmitting the power from the front wheel 12a to the front wheels 12. Similarly, a gear-type rear wheel drive mechanism 15 is provided to drive the rear wheel 13, and the rear wheel drive mechanism 15 uses a rear wheel drive motor 15a and power from the rear wheel drive motor 15a. It is constituted by a gear-type transmission mechanism 15b for transmitting to the rear wheel 13.

The front wheel drive mechanism 14 is rotatable about the axis Y in the vertical direction of the bogie together with the front wheels 12, and a front wheel steering mechanism 16 is provided for this purpose. Similarly, rear wheel 1
3 is also rotatable around the axis Y in the vertical direction of the bogie by the rear wheel steering mechanism 17. The front and rear wheel steering mechanisms 16 and 17
Each is composed of steering motors 16a and 17a and gear transmission mechanisms 16b and 17b including a worm gear. The front wheel 12 includes an axle 12a and a pair of steel wheels 12b attached to both ends of the axle.
Is constituted by a magnet, the wheel body 12b is magnetically attracted to the inner peripheral surface of the iron pipe or the steel pipe. The rear wheel 13 also includes an axle 13a, which is a magnet, and a steel wheel 13b. This allows
The in-pipe traveling cart 10 can also make a round in the inclined pipe or in the pipe in the circumferential direction. In addition, the traveling truck 1
In order to detect various data related to driving,
For example, a front wheel steering angle sensor 18a, a rear wheel steering angle sensor 18b, and a traveling speed sensor 18 for detecting a driving speed
c, a sensor group 18 such as a rolling sensor 18d for detecting a posture in the direction of gravity is provided.

A bracket 19 is suspended from the center of the vehicle body 11, and a PPM is attached to the lower end of the bracket 19.
An electromagnetic ultrasonic transducer 2 is mounted.
As shown schematically in FIG. 2, the PPM electromagnetic ultrasonic transducer 2 includes a magnet unit 3 and a pair of a transmitting spiral coil 4a and a receiving spiral coil 4b arranged on the lower surface of the magnet unit 3. Spiral coil 4 and these spiral coils 4a, 4b
It comprises a separation membrane 4c made of polyamide provided therebetween and a shoe 5 for supporting these spiral coils 4. The magnet unit 3 is a permanent magnet 3a with the S pole facing up.
And an alternating magnetic field forming magnet row 40 in which permanent magnets 3a having N poles facing up are arranged alternately in two rows in the left-right direction, and the permanent magnets 3a are arranged in the row direction of the permanent magnets 3a. An alternating magnetic field whose direction of the magnetic flux is reversed at a pitch is generated. Spacers 3b are interposed between the permanent magnets 3a.

In the case of this configuration, the major axis Z of the spiral coils 4 a and 4 b formed in an elliptical shape is a pair of alternating magnetic field forming magnet rows 40 forming the magnet unit 3.
It is arranged at a position corresponding to the intermediate shaft Ca in the middle between the left and right in the vertical direction. Here, the transmission spiral coil 4a generates an eddy current in the metal body of the tube 1 for generating a Lorentz force substantially parallel to the tube 1 having the coating 1A as the surface of the detection object. Wound and arranged. Thereby, in the positional relationship of FIG. 1, a horizontally polarized transverse wave, that is, an SH wave, is excited in the tubular body 1. Conversely, when the SH wave returns below the PPM electromagnetic ultrasonic transducer 2, an eddy current is generated, and the eddy current generates a current in the receiving spiral coil 4b.

FIG. 2 is a block diagram of an electronic system of a detection apparatus using the PPM electromagnetic ultrasonic transducer according to the present invention. The terminal microcomputer 100 constituting the core of the electronic system receives a signal from a sensor group 18 composed of various sensors provided on the in-pipe traveling carriage 10, and receives a traveling motor 14 a for driving the front wheels 12 and the rear wheels 13. 1
An operation signal is output to the driver 5a via the driver 101, and an operation signal is output to the steering motors 16a and 17a for steering the front wheel 12 and the rear wheel 13 via the driver 102. Similarly to the above, the terminal microcomputer 100
In order to operate the PM electromagnetic ultrasonic transducer 2,
An operation signal is sent to the high-frequency transmitter 32 via the driver 31, and the drive signal generated by the high-frequency transmitter 32 is amplified by the amplifier 33 and then supplied directly to the transmission spiral coil 4 a of the PPM electromagnetic ultrasonic transducer 2. Then, the SH wave is excited in the tube. Since the SH wave returning through a predetermined propagation path generates a current in the spiral coil 4b for reception of the PPM electromagnetic ultrasonic transducer 2, this current is supplied to the amplifier 35 and the band pass filter (BPF) 3.
6. The terminal microcomputer 100 via the A / D converter 37
To be detected.

In order to achieve the above-mentioned functions, the terminal microcomputer 100 is basically provided with two main functions created by a program, that is, the in-pipe traveling vehicle is moved in the longitudinal direction of the vehicle body 11 or the vehicle body 11. A traveling control unit 6 for traveling in the transverse direction and a peeling evaluation unit 7 for specifying the position of the peeling portion based on a signal detected by the PPM electromagnetic ultrasonic transducer 2 are provided. As shown in FIG. 3, the peeling evaluation unit 7 includes a sound pressure determining unit 71 that determines the amplitude of the detection signal input from the A / D converter 37, that is, the sound pressure level of the SH wave, and the sound pressure determining unit. An LUT (look-up table) 72 which tabulates the relationship between the sound pressure level determined at 71 and the size of the peeled portion using the object, in this case, the position of the coating 1A of the tube 1 and the ultrasonic attenuation rate as parameters. And a peeling part position determining means 73 for determining the depth and position of the peeling part 1B from the sound pressure level determined by the sound pressure determining means 71 while referring to the LUT 72. In this embodiment, since the detection method based on the transmission method is adopted, the SH wave sent out from the transmission spiral coil 4a in the circumferential direction of the tube 1 is circulated in a state where scattering is unlikely to occur due to the presence of the separation portion 1B. It propagates in the direction and is detected by the receiving spiral coil 4b. The detected sound pressure level of the SH wave is higher than the sound pressure level in the case where there is no separation by the amount of attenuation when passing through the coating 1A. In this case, the attenuation rate of the ultrasonic wave between the metal tube and the coating is larger in the coating than in the case of the material.
On the other hand, if the metal pipe alone has a thinning defect, the sound pressure level is reduced. That is, the phenomena that occur are reversed.
Of course, it is also possible to adopt a reflection method, in which case only the sound pressure level of the SH wave (so-called stripping section echo) capturing the stripping section 1B may be considered, but the attenuation due to the distance to the stripping section 1B. In consideration of the above, it is convenient to use a linear or, if necessary, non-linear amplifier for defect evaluation.

Next, an SH wave (0... 0) propagating in the circumferential direction using the above-described PPM electromagnetic ultrasonic transducer 2 is applied to the peeling portion 1 B artificially provided on the coating 1 A of the tubular body 1.
52MH _Z) detected by the experimental results by a transmission method using the Figure 4
Is shown in FIG. 4 shows a test piece (gas pipe: S) provided with a peeling portion 1B over a length of 20 cm from a position 20 cm in the axial direction from the reference point to a position approximately 40 cm from the starting point.
10 is a graph showing a signal level (sound pressure level: volt) obtained when the PPM electromagnetic ultrasonic transducer 2 is moved in the axial direction from a reference point with respect to the GP200A).
From this graph, it can be understood that the position and size of the peeling portion 1B and the increase in the detection signal level (because the transmission method is employed) show an extremely strong correlation. Therefore,
By collecting a large number of such experimental data and tabulating or formulating the relationship between the position of the peeling part 1B and the rise of the detection signal level for each material having various sound wave characteristics, the presence / absence of the peeling part, the position, and the peeling It is possible to evaluate to the extent.

In the above-described embodiment, since the transmission method using the SH wave propagating in the circumferential direction with respect to the tube body 1 is employed, the transmitting / receiving PPM electromagnetic ultrasonic transducer also serves as the magnet unit 3. However, when a transmission method using an SH wave propagating in the axial direction with respect to the tube 1 or a transmission method for a plate material is adopted, a transmitting PPM electromagnetic ultrasonic transducer and a receiving PPM electromagnetic ultrasonic transducer are used. Is required. The layout of the two transducers is appropriately selected according to the detection target, as is well known in the conventional ultrasonic transmission method.

[Other Embodiments] In the above embodiment, the case where a pair of spiral coils 4a and 4b are used for transmission and reception has been described.
A case where a single spiral coil (elliptical coil) 4 is provided in the transducer and used for both transmission and reception will be described. This example is shown in FIG. In this example, the PPM electromagnetic ultrasonic transducer 2 is
As schematically shown in FIG. 2, a magnet unit 3 having the same configuration as in FIG. 2, a spiral coil 4 disposed on the lower surface of the magnet unit 3, and a And a shoe 5. The spiral coil 4 plays a role of generating an eddy current in the metal tube for generating a Lorentz force substantially parallel to the metal tube of the tube 1 as the surface of the detection object. Thereby, a horizontally polarized transverse wave in the metal tube, that is, an SH wave is excited, and the SH wave propagates also in the coating device 1A.
When the SH wave returns below the PPM electromagnetic ultrasonic transducer 2, an eddy current is generated, and the eddy current generates a current in the spiral coil 4. Therefore, this current can be detected. FIG. 5 also shows the electronic system of the PPM electromagnetic ultrasonic transducer according to this example.
Is shown in correspondence with. The terminal microcomputer 100 sends an operation signal to a high-frequency transmitter 32 via a driver 31 to operate the PPM electromagnetic ultrasonic transducer 2, and after a drive signal generated by the high-frequency transmitter 32 is amplified by an 34 to the spiral coil 4 of the PPM electromagnetic ultrasonic transducer 2;
The SH wave is excited in the tube. The SH wave returned via a predetermined propagation path is detected by the spiral coil 4 of the PPM electromagnetic ultrasonic transducer 2, and this detection signal is amplified by an amplifier 35, a band pass filter (BPF) 36, and further A / D converted. It is sent to the terminal microcomputer 100 via the device 37. Therefore, the only difference between this configuration and the configuration in FIG. 2 is the presence or absence of the diplexer. The information obtained is
In the same manner as described above, it is sent to the peeling evaluation section 7 and the peeling evaluation can be performed.

[Brief description of the drawings]

FIG. 1 is a side view of an in-pipe traveling cart equipped with a coating / shedding peeling portion detecting device using a PPM electromagnetic ultrasonic transducer according to the present invention.

FIG. 2 is a block diagram of a coating and peeling portion detecting apparatus using a PPM electromagnetic ultrasonic transducer according to the present invention;

FIG. 3 is a block diagram of a peeling evaluation unit.

FIG. 4 is a graph showing experimental results.

FIG. 5 is a diagram showing another configuration example of the PPM electromagnetic ultrasonic transducer according to the present invention.

[Explanation of symbols]

 2 PPM electromagnetic ultrasonic transducer 71 Sound pressure determining means 73 Defect size determining means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshimichi Kitaoka 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture F-term in Osaka Gas Co., Ltd. (reference) 2G047 AA06 AB05 AB07 BC03 CA02 CB04 GA19 GC01 GC04 GG09 GG17 GG36 GJ02

Claims (4)

[Claims] 1. A PP that excites and transmits ultrasonic waves to a metal body provided with a coating on the surface and receives the returned ultrasonic waves.
An MEP ultrasonic transducer, and a peeling part detecting apparatus using a PPM electromagnetic ultrasonic transducer, comprising: a peeling evaluation unit for evaluating a peeling state of the coating based on the sound pressure of the received ultrasonic wave. . 2. The metal body provided with the coating device is a tube, and the PPM electromagnetic ultrasonic transducer transmits ultrasonic waves in the circumferential direction of the tube and receives transmitted ultrasonic waves circling the tube. 2. The PPM of claim 1, wherein
A coating / peeling-off part detecting device using an electromagnetic ultrasonic transducer. 3. The peeling evaluation section determines that a peeling section exists when the sound pressure of the received ultrasonic wave is higher than the sound pressure of the ultrasonic wave in the reference state where the peeling section does not exist. A coating and peeling portion detecting apparatus using the PPM electromagnetic ultrasonic transducer according to the above item. 4. A pair of alternating magnetic field forming magnet rows each comprising a plurality of permanent magnets whose polarities are inverted in the vertical direction alternately in each row, wherein the PPM electromagnetic ultrasonic transducer is provided with: A magnet unit having a configuration in which the magnet rows are arranged in two rows on the left and right sides with a phase different in polarity by 180 degrees from each other; A credit spiral coil and a receiving spiral coil are separately and separately provided at a lower position of the magnet unit via a separation membrane, and a transmitting / receiving PPM is provided.
An electromagnetic ultrasonic transducer is configured.
3. A coating-covered peeling-off section detecting apparatus using the PPM electromagnetic ultrasonic transducer according to any one of 3.