JP2012211830A - Insertion type ultrasonic flaw detection sensor and ultrasonic flaw detection method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insertion type ultrasonic flaw detection sensor capable of obtaining high S/N when detecting flaws from the inside of a tube, and to provide an ultrasonic flaw detection method using the insertion type ultrasonic flaw detection sensor.SOLUTION: An insertion type ultrasonic flaw detection sensor 10 detects flaws from the inside of a tube 80. This sensor includes: an ultrasonic transducer 22 having a vibration surface 23 having a shape in which ultrasonic waves can be oscillated so as to form a line focus in a focal position; and a sensor body 24 which can be moved in the tube 80 along a tube axis. The sensor body 24 holds the ultrasonic transducer 22 so that the line focus is formed to be along the circumferential direction of the tube 80 on the inner peripheral surface 86 of the tube 80.

Description

  The present invention relates to an interpolated ultrasonic flaw detection sensor for detecting flaws, thinnings, and the like occurring in a pipe wall of a pipe from the inside of the pipe using ultrasonic waves, and an ultrasonic flaw detection method using the same.

  Conventionally, an interpolated ultrasonic flaw detection sensor (hereinafter simply referred to as “flaw detection”) that oscillates ultrasonic waves from the inside of a pipe toward the pipe wall and receives the ultrasonic waves returned from the pipe wall. A sensor described in Patent Document 1 is known as a “sensor”.

  As shown in FIG. 9, the flaw detection sensor includes an ultrasonic transducer 104 having a flat vibration surface 102 and is connected to a flaw detection device 106 by a cable 108.

  The flaw detection sensor 100 is inserted into a tube 110 that is an object to be inspected, oscillates the vibration surface 102 based on an oscillation signal from the flaw detection device 106, oscillates an ultrasonic wave, and the returned ultrasonic wave is subjected to ultrasonic vibration. The data is received by the child 102, converted into a received signal, and output. The flaw detection apparatus 106 receives the received signal from the flaw detection sensor 100 via the cable 108 and analyzes it. As a result, if a flaw (material flaw) such as thinning or blowhole occurs on the tube wall, this flaw is detected.

JP-A-6-94685

  However, when ultrasonic waves are oscillated by the ultrasonic transducer 104 of the flat vibration surface 102 as in the flaw detection sensor 100 described above, as shown in FIG. Since the sound wave diffuses, the ultrasonic wave (reflected echo) that is reflected and returned from the outer peripheral surface side of the tube 110 becomes small. Thus, when the reflected echo received by the ultrasonic transducer 104 becomes small, the ratio of the noise component increases, so the S / N becomes low and it becomes difficult to obtain the S / N necessary for flaw detection.

  On the other hand, a point focus type ultrasonic transducer that concentrates ultrasonic waves at one point (focal point) is known.

  Therefore, the flaw detection sensor including this point focus type ultrasonic transducer is usually used for flat plate flaw detection, but it can be considered to be used for flaw detection from the inside of the tube 110.

  However, as shown in FIG. 11, the ultrasonic wave oscillated by this point focus type ultrasonic transducer is generated by the ultrasonic wave traveling along the cross section perpendicular to the tube axis c. By converging in front, the reflected echo diffuses and the reflected echo received by the ultrasonic transducer 104A becomes smaller. The convergence of the ultrasonic waves before the outer peripheral surface 110a is caused by the curved inner peripheral surface 110b of the tube 110. Thus, even with the flaw detection sensor 100A using the point focus type ultrasonic transducer 104A, when flaw detection is performed from the inside of the tube 110, the S / N becomes low, and it becomes difficult to obtain the S / N necessary for flaw detection.

  In particular, when the length of the cable connecting the flaw detection sensor and the flaw detection device is increased in order to perform flaw detection on a long tube, the noise included in the received signal reaching the flaw detection device increases and the S / N decreases. Become prominent.

  Therefore, in view of the above problems, the present invention provides an interpolated ultrasonic flaw detection sensor that can obtain a high S / N when flaw detection is performed from the inside of a tube, and an ultrasonic flaw detection method using the same. And

  Accordingly, in order to solve the above-described problems, the present invention is an insertion type ultrasonic flaw detection sensor that performs flaw detection from the inside of a tube, and has a vibration surface that is capable of oscillating ultrasonic waves so that line focus is achieved at the focal position. And an ultrasonic transducer having a sensor body movable along the tube axis, and the sensor body is arranged such that the line focus is along the circumferential direction of the tube on the inner circumferential surface of the tube. And holding the ultrasonic transducer.

  Further, in order to solve the above-mentioned problems, the present invention is an ultrasonic flaw detection method for performing flaw detection from the inside of a tube, and is an interpolated ultrasonic flaw detection sensor that oscillates ultrasonic waves so as to form a line feature at a focal position. And oscillating the ultrasonic wave so that the line focus is along the circumferential direction of the tube on the inner peripheral surface of the tube.

  According to these inventions, the focal point of the ultrasonic wave oscillated by the interpolated ultrasonic flaw detection sensor becomes a line focal point along the circumferential direction of the tube on the inner peripheral surface of the tube, so that the axial direction of the tube The ultrasonic wave traveling along the longitudinal section converges on the outer peripheral surface of the tube (see FIG. 5A), and the ultrasonic wave traveling along the transverse section in the direction perpendicular to the axis of the tube converges on the outer circumferential surface ( Therefore, the ultrasonic transducer can receive a sufficient reflected echo. Thereby, according to the said insertion type | mold ultrasonic flaw detection sensor, high S / N is obtained.

  Specifically, the vibration surface is curved so as to be recessed on the opposite side of the ultrasonic oscillation direction in the longitudinal section of the tube along the tube axis, and the most recessed portion extends along the circumferential direction. Have a different shape.

  As described above, according to the present invention, it is possible to provide an insertion type ultrasonic flaw detection sensor that can obtain a high S / N when flaw detection is performed from the inside of a tube, and an ultrasonic flaw detection method using the same.

It is a schematic block diagram of the flaw detection apparatus which concerns on this embodiment. It is an enlarged view of the probe part of the flaw detection sensor of the said flaw detection apparatus. (A) is IIIA-IIIA sectional drawing of FIG. 2, (B) is IIIB-IIIB sectional drawing of FIG. FIG. 4 is a partially enlarged cross-sectional view of the probe portion at the IV-IV position in FIG. It is a figure for demonstrating propagation of the ultrasonic wave oscillated from the ultrasonic transducer | vibrator of the said flaw detection sensor. It is a figure which shows the intensity | strength of the reflective echo detected by the said flaw detection sensor. (A) is a figure which shows the intensity | strength of the reflective echo detected by the flaw detection sensor provided with the ultrasonic transducer | vibrator of a flat vibration surface, (B) is the flaw detection sensor provided with the point focus type | mold ultrasonic transducer | vibrator. It is a figure which shows the intensity | strength of the reflective echo detected by (1). It is a schematic diagram for demonstrating the vibration surface of the ultrasonic transducer | vibrator of other embodiment, Comprising: (A) is the figure seen from the pipe-axis direction, (B) is the figure seen from the direction orthogonal to a pipe axis. It is. It is a figure for demonstrating the conventional flaw detection sensor. It is a figure for demonstrating propagation of the ultrasonic wave oscillated from the ultrasonic transducer | vibrator of a flat vibration surface. It is a figure for demonstrating propagation of the ultrasonic wave oscillated from the point focus type ultrasonic transducer.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, based on FIG. 1, an outline of a flaw detection apparatus 1 including an interpolated ultrasonic flaw detection sensor (hereinafter also simply referred to as “flaw detection sensor”) 10 will be described, and then the flaw detection sensor 10 will be described.

  The flaw detection apparatus 1 includes an ultrasonic flaw detector 2, a flaw detection sensor 10, a flaw detection cable (hereinafter also simply referred to as “cable”) 3, and a feeding portion 4 for feeding the flaw detection sensor 10 into a pipe.

  The ultrasonic flaw detector 2 outputs an oscillation signal to the flaw detection sensor 10 and receives a reception signal from the flaw detection sensor 10, and analyzes the reception signal to detect a flaw (material flaw) of the inspection object. 5 and a recording unit 6 for recording a flaw detection result in the flaw detector main body 5. In the present embodiment, a PC is used as the recording unit 6.

  The cable 3 connects the flaw detection sensor 10 and the flaw detector main body 5, transmits an oscillation signal from the flaw detector main body 5 to the flaw detection sensor 10, and transmits a reception signal from the flaw detection sensor 10 to the flaw detector main body 5. The cable 3 of the present embodiment has a length longer than that of the pipe 80 that is the inspection object, for example, because the length is 90 m.

  The feeding section 4 includes a water pump 7 and a water jet nozzle section 8 that feeds water supplied from the water pump 7 into the pipe 80 that is an inspection object together with the flaw detection cable 3.

  Next, the flaw detection sensor 10 will be described.

  The flaw detection sensor 10 includes a probe unit 20, a pair of coil springs 12 and 12 disposed on both sides of the probe unit 20, a tip guide unit 14, and a plurality (four in this embodiment) of alignment units 30. And a plurality of cover members 50.

  As shown in FIGS. 2 to 4, the probe unit 20 includes a plurality of (eight in the present embodiment) ultrasonic transducers 22 and a sensor body 24 that holds the ultrasonic transducers 22. Prepare.

  The ultrasonic vibrator 22 has a vibration surface 23, and oscillates the vibration surface 23 based on the input oscillation signal, and at the same time when the ultrasonic wave is received by the vibration surface 23. The vibration of the vibration surface 23 is converted into a reception signal and output.

  The ultrasonic transducer 22 oscillates a 15 MHz ultrasonic wave, but is not limited to this frequency, as long as it can oscillate an ultrasonic wave of 5 MHz to 20 MHz.

  The vibration surface 23 has a shape capable of oscillating ultrasonic waves so as to be line focus (line focus) at the focus position. Specifically, the vibration surface 23 is recessed on the opposite side of the ultrasonic oscillation direction in the central longitudinal section along the axial direction of the substantially cylindrical sensor body 24, and the most recessed portion is orthogonal to the central longitudinal section. It is curved to extend in the direction (or along the circumferential direction of the sensor body 24). Specifically, the vibration surface 23 is curved in an arc shape in the central longitudinal section (see FIG. 4), and is linear in the transverse section of the sensor body 24 (see FIGS. 3A and 3B). ). That is, the vibration surface 23 has an arc shape with the same curvature in each cross section parallel to the central vertical cross section. The curved shape (curvature, etc.) along the central longitudinal section of the vibration surface 23 is such that the curvature of the inner peripheral surface 86 of the tube 80 that is the specimen object and the distance from the vibration surface 23 to the inner peripheral surface 86 of the tube 80. Determined by.

  The sensor body 24 is a substantially cylindrical member in which the ultrasonic transducer 22 is disposed, and a plurality of (eight in the present embodiment) holes 26 are provided on the peripheral surface. The sensor main body 24 holds the ultrasonic transducer 22 at a position corresponding to each hole 26 in the sensor main body 24. The sensor body 24 holds each ultrasonic transducer 22 so that the line focus of the ultrasonic wave oscillated from the vibration surface 23 is along the circumferential direction of the tube on the inner peripheral surface 86 of the tube 80. Specifically, the sensor body 24 holds the ultrasonic transducer 22 so that the direction in which the most depressed portion of the vibration surface 23 extends is along the circumferential direction of the sensor body 24. At this time, the ultrasonic transducer 22 may be mounted in the hole 26 of the sensor main body 24, and at a position corresponding to the hole 26 inside the sensor main body 24 (so that the vibration surface 23 is exposed to the outside). ) It may be attached. As a result, the ultrasonic wave oscillated from the vibration surface 23 of each ultrasonic transducer 22 is directed to the tube wall (tube 80) and the ultrasonic wave (reflected echo) returned from the tube wall is transmitted to each ultrasonic transducer 22. The vibration surface 23 is reached.

  The holes 26 are arranged at equal intervals in the circumferential direction at a plurality of axial positions of the sensor main body 24 (in this embodiment, two locations). Moreover, in the row | line | column of the said circumferential direction hole 26 adjacent in the axial direction of the sensor main body 24, the adjacent holes 26 and 26 have shifted | deviated to the circumferential direction. As a result, if the flaw detection sensor 10 is moved in the tube axis direction, the tube wall can be flawed over the entire circumference. The circumferential holes 26 may be arranged in a single row. Further, only one ultrasonic transducer 22 may be provided in the sensor body 24.

  The pair of coil springs 12 and 12 extend from the probe unit 20 to both sides, respectively. Specifically, each coil spring 12 is disposed so as to extend in the axial direction from both axial ends of the sensor body 24. The coil spring 12 has a spring constant such that the coil spring 12 does not bend or bend in the middle when the probe unit 20 is pushed through the coil spring 12 in the straight tube portion 82 (see FIG. 1) of the tube 80. .

  Inside the coil spring 12 on the base side (right side in FIG. 1) of the flaw detection sensor 10, electric wires (not shown) extending from the respective ultrasonic transducers 22 of the probe unit 20 are arranged. Are connected electrically to the cable 3. Thereby, transmission / reception of the signal between the flaw detector main body 5 and each ultrasonic transducer 22 becomes possible.

  The tip guide portion 14 is a spherical member. The tip guide portion 14 is provided at the leading position of the flaw detection sensor 10, and the tip guide portion 14 advances in the tube 80 while being in sliding contact with the pipe inner peripheral surface 86 at a curved portion 84 or the like of the tube 80. However, it becomes easy to advance along the bending of the tube 80 or the like.

  Each alignment unit 30 is for positioning the probe unit 20 at the center in the radial direction in the tube 80 when the flaw detection sensor 10 is inserted into the tube 80, and is a plate-shaped alignment unit main body 32. Is provided.

  The alignment part main body 32 is a plate-like member that extends in a direction orthogonal to the direction of the center line C of the coil spring 12 (see FIG. 2), and has a contact surface 32a at the tip thereof. Then, the alignment unit main body 32 causes the abutment surface 32a to abut against the inner peripheral surface 86 of the tube 80 when the flaw detection sensor 10 is inserted into the tube 80 (see FIG. 1). The probe unit 20 is positioned in the position. That is, when the flaw detection sensor 10 is located in the tube, the distance from the inner peripheral surface 86 of the tube 80 to the ultrasonic transducer 22 (vibration surface 23) of the probe unit 20 is maintained substantially constant. The alignment part main body 32 is formed of, for example, a resin such as nylon, polypropylene, or rubber.

  Each cover member 50 is a member for preventing the coil spring 12 from coming into contact with the pipe inner peripheral surface 86, and is a spherical member through which the coil spring 12 penetrates the central portion. The cover member 50 is formed of polytetrafluoroethylene, but is not limited thereto, and may be formed of a resin such as nylon or polypropylene.

  The cover member 50 is disposed over the entire region where the alignment portion 30 is not disposed in the direction of the center line C of the coil spring 12. That is, in the flaw detection sensor 10, the coil spring 12 is covered with the plurality of alignment portions 30 and the plurality of cover members 50.

  According to the flaw detection apparatus 1 including the flaw detection sensor 10 as described above, the tube 80 is flaw-detected as follows.

  The flaw detection sensor 10 is inserted from one end of the tube 80 which is an inspection object. The inspection object in the present embodiment is, for example, a pipe (for example, a steel pipe or a stainless steel pipe) 80 having a total length of 90 m, a pipe inner diameter of 28 mm, a curved portion with a radius of curvature of 57 mm, and seven curved portions (for example, a steel pipe or a stainless pipe). (See FIG. 1).

  Next, water is poured into the pipe 80 by the feeding section 4, and the flaw detection sensor 10 is pushed (moved) in the pipe 80 using the water pressure. At this time, the contact surface 32a of the alignment unit main body 32 contacts the inner peripheral surface 86 of the tube, whereby the probe 20 is supported at the radial center of the tube 80. In this state, the flaw detection sensor 10 is Move in the tube 80. As a result, the distance from the inner peripheral surface 86 of the tube 80 to the ultrasonic transducer 22 (specifically, the vibration surface 23) of the probe unit 20 is constant (or approximately) even if the flaw detection sensor 10 moves within the tube 80. Constant).

  As described above, the flaw detection sensor 10 moves in the tube 80 and the probe unit 20 transmits and receives ultrasonic waves, so that each part of the tube 80 is flawed. Specifically, based on the oscillation signal from the ultrasonic flaw detector 2 (specifically, the flaw detector main body 5), the vibration surface 23 of each ultrasonic transducer 22 of the probe unit 20 vibrates, so that the tube wall Oscillates ultrasonic waves toward

  The ultrasonic wave oscillated by the vibration of the vibration surface 23 is focused on the inner peripheral surface 86 of the tube 80 along the line focus along the circumferential direction of the tube 80. The ultrasonic wave traveling along the outer surface 87 of the tube 80 converges on the outer peripheral surface 87 (see FIG. 5A), and the ultrasonic wave traveling along the cross section in the direction orthogonal to the axis of the tube 80 converges on the outer peripheral surface 87. (See FIG. 5B). This is because the inner peripheral surface is curved. And each ultrasonic transducer | vibrator 22 receives the said ultrasonic wave reflected and returned by this outer peripheral surface 87, respectively. As a result, the reflected echo does not diffuse (see FIGS. 10 and 11) unlike the case of using a conventional ultrasonic vibrator having a flat vibration surface or a point focus type ultrasonic vibrator (see FIGS. 10 and 11). The transducer 22 can receive a sufficient reflected echo. As a result, according to the flaw detection sensor 10, high S / N can be obtained.

  Each ultrasonic transducer 22 that has received the reflected echo converts these into reception signals and outputs them to the ultrasonic flaw detector 2 (flaw detector main body 5). Then, the flaw detector main body 5 analyzes the received signal to detect cracks such as cracks and thinning on the tube wall of the tube 80, and outputs the result to the recording unit 6. The recording unit 6 records this and displays the detection result.

  According to the flaw detection sensor 10 of the above embodiment, a high S / N can be obtained during flaw detection. Therefore, even if the length of the tube 80 is large (for example, 100 m or more), that is, even if the cable 3 that connects the flaw detection sensor 10 and the ultrasonic flaw detector 2 is long, the S / N is high. It becomes possible to detect flaws with high accuracy. In particular, when the length of the cable 3 exceeds about 40 m, it is possible to obtain a high S / N ratio compared to a flaw detection sensor having an ultrasonic transducer having a flat vibration surface or a point focus type ultrasonic transducer. Becomes prominent. Further, when flaw detection is performed on the tube 80 having a large curvature on the inner peripheral surface with an inner diameter of 60 mm or less, compared to a flaw detection sensor having an ultrasonic transducer having a flat vibration surface or a point focus type ultrasonic transducer. The effect of obtaining a high S / N is remarkable.

  In order to confirm the effectiveness of the flaw detection sensor 10 according to the above embodiment, the flaw detection sensor 10 according to the above embodiment, a flaw detection sensor (flat type flaw detection sensor) including an ultrasonic transducer having a flat vibration surface, and a point focus type The flaw detection sensor (point focus type flaw detection sensor) provided with the ultrasonic transducer is used for flaw detection of the tube 80, and the surface echo height and outer peripheral surface 87 returned from the inner peripheral surface 86 of the tube 80 in the flaw detection result. We observed the bottom echo height returned from the bottom. The tube 80 used at this time has an inner diameter of 38 mm and a wall thickness of 6.5 mm, as in the above embodiment.

  The flaw detection results are shown in FIGS. FIG. 6 is a diagram showing the intensity of the reflected echo detected by the flaw detection sensor 10 of the above embodiment. FIG. 7A is a diagram showing the intensity of the reflected echo detected by the flat type flaw detection sensor. FIG. 7B is a diagram showing the intensity of the reflected echo detected by the point focus type flaw detection sensor.

  From these figures, according to the flaw detection sensor 10 of the above-described embodiment, the bottom surface echo height (reception intensity of the bottom surface echo) is about 3 as compared with the case where flaw detection is performed using a flat type flaw detection sensor or a point focus type flaw detection sensor. It can be seen that it is twice as high (about 10 dB). As a result, it is confirmed that by using the flaw detection sensor 10 of the above embodiment, flaw detection with a high S / N is possible as compared with the case where flaw detection is performed using a flat type flaw detection sensor or a point focus type flaw detection sensor. It was.

  In addition, the flaw detection sensor of the present invention and the ultrasonic flaw detection method using the same are not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention. .

  For example, in the above embodiment, the vibration surface 23 is a continuous smooth curved surface. However, as shown in FIGS. 8A and 8B, the vibration surface 230 has a longitudinal section in the tube axis direction. The shape which combined several planes may be sufficient. That is, the vibration surface may be a line focus (line focus) at which the oscillated ultrasonic wave is at the focal position.

  Moreover, in the flaw detection sensor 10 of the said embodiment, although the probe part 20 is one, multiple may be provided.

DESCRIPTION OF SYMBOLS 10 Interpolation type ultrasonic flaw detection sensor 20 Probe part 22 Ultrasonic vibrator 23 Vibration surface 24 Sensor main body 80 Pipe 86 Inner peripheral surface 87 Outer peripheral surface

Claims (3)

An interpolated ultrasonic flaw detection sensor that performs flaw detection from the inside of a tube,
An ultrasonic transducer having a vibrating surface with a shape capable of oscillating ultrasonic waves so as to be line focus at the focal position;
A sensor body movable along the tube axis in the tube,
The sensor main body is an insertion type ultrasonic flaw detection sensor that holds the ultrasonic transducer so that the line focus is along the circumferential direction of the tube on the inner peripheral surface of the tube.   The vibration surface has a shape that is curved so as to be recessed on the opposite side of the ultrasonic oscillation direction in the longitudinal section of the tube along the tube axis, and has a shape in which the most recessed portion extends along the circumferential direction. Insertion type ultrasonic flaw detection sensor. An ultrasonic flaw detection method that performs flaw detection from the inside of a tube,
The ultrasonic wave is oscillated so that the line focus is along the circumferential direction of the tube on the inner peripheral surface of the tube from the interpolated ultrasonic flaw detection sensor that oscillates the ultrasonic wave so as to be a line feature at the focal position. An ultrasonic flaw detection method comprising a process.

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