JP2006250873A - Ultrasonic flaw detecting method and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reducing multiple reflections between the surface of a phased array probe and the surface of a material to be tested. <P>SOLUTION: An apparatus for ultrasonic flaw detection is provided with a plurality of phased array probes 1-1 for surrounding an outer circumference of a columnar or cylindrical specimen m and forming an arc having the same radius, and detects flaws in the specimen m. In ultrasonic flaw detecting method, the phased array probes 1-1 are a plurality of oscillators 10-10 disposed in an arc, and offset to the specimen m so as to have an eccentric distance d between a bisector (a virtual line) for equally dividing a central angle of the arc, formed by the phased array probes 1-1 and the center of the specimen m on a plane (a virtual plane) for intersecting the axial direction with respect to the material to be tested. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic flaw detection method and an apparatus therefor.

When performing an ultrasonic flaw detection on a round bar (column) or a cylindrical material to be inspected (hereinafter referred to as a material to be inspected), a rotational scan of an old physical probe (or a probe is used for rapid flaw detection). As an alternative to the fixed rotation method, a series of vibrations are used using an array probe in which a plurality of transducers (elements) are arranged around the outer periphery of the test material. There has been proposed one that shifts several pieces and vibrates sequentially to emit ultrasonic waves toward each position on the outer periphery of the specimen (Patent Document 1).
Incidentally, in the array probe in which the elements are arranged in a ring shape as described above, it is necessary to replace the whole element due to a defect of some elements during maintenance. For this reason, the inventor of the present application has considered that a plurality of arc-shaped phased array probes in which a plurality of elements are arranged in an arc shape are used so as to surround the outer periphery of the test material. That is, a plurality of arc-shaped array probes are used to divide the circumference into blocks and perform flaw detection.
Others have also been proposed that perform flaw detection by dividing the circumference into blocks (Patent Documents 2 and 3).

JP 59-126952 A Japanese Utility Model Publication No. 3-11734 (Japanese Patent Laid-Open No. 59-63560) Japanese Examined Patent Publication No. 1-343906

On the other hand, if an ultrasonic beam rotating type flaw detector for pipes (cylinders) or pipettes (cylinders) is to be realized with the above-mentioned phased array probe (array probe), the pulse is used regardless of whether or not the blocks are divided. There was a problem that the repetition frequency did not increase.
This point will be described in detail with reference to FIG. 9 (conceptual diagram).
In the conventional flaw detection apparatus, as shown in FIG. 9 (A), a phased array probe having a test material having a circular cross section such as a pipe or a pillet and an arc-shaped cross section (a plurality of transducers 10 are arranged in an arc shape). 1 and the probe storage block J are arranged on a concentric circle (M indicates the center of the test material m), and the flaw detection for coupling between the test material m and the probe storage block J including the phased array probe 1 is performed. Filled with water w (in FIG. 9, hatching to be attached to the test material m is omitted in order to avoid complication of the drawing).
Specifically, this ultrasonic flaw detector is configured so that the center of the specimen m is placed on a bisector t1 that bisects the center angle φ of the arc exhibited by the phased array probe 1 with respect to the specimen m. Physical arrangement is taken so that M is located.

In the conventional ultrasonic flaw detector described above, as shown in FIG. 9B, the transmitting array element (vibrator 10... 10) of the array probe 1 is ultrasonically excited with a phase-controlled pulse to generate ultrasonic waves. Is sent to the test material m, and the flaw detection water w for coupling is passed. Some of the ultrasonic waves that have arrived at the test material m are incident on the surface of the test material m on the surface of the test material m, and others are reflected on the surface of the test material m. The incident ultrasonic wave propagates inside the test material m, and is reflected or refracted by a defect in the material (test material m) and an acoustic impedance mismatching surface (not shown). The reflected or refracted ultrasonic wave returns to the surface of the test material m again, and a part of the ultrasonic wave propagates to the flaw detection water w for coupling, and the ultrasonic wave is finally used for reception. Reach the array element. In the receiving array element, the ultrasonic wave is converted into an electric signal, amplified, phase-delayed, phase-synthesized, and sent to the evaluation circuit.
After a series of operations from sending to receiving is completed, the receiving array element for sending is shifted by an appropriate number of elements, and the same sending and receiving sequence as described above is repeated. This repetition period is called an ultrasonic repetition period, and this reciprocal is called an ultrasonic repetition frequency. This ultrasonic repetition period is mainly determined by the remaining time of a reverberant ultrasonic signal (also called a ghost echo).
The main components of the reverberant ultrasonic signal are multiple reflections between the phased array probe surface and the surface of the test material m in the flaw detection water for coupling, and the probe storage block surface and the surface of the test material m. Multiple reflections between them.
For this reason, it is necessary to wait for the multiple reflections of the ultrasonic waves by one arc-shaped array probe to attenuate until the defective echoes in question can be distinguished, and then fire the next ultrasonic wave. The length of the reverberation time described above hindered the speed of flaw detection (the next pulse could not be emitted quickly).
Here, for multiple reflections between the probe storage block surface and the surface of the test material, the surface of the probe storage block is made of a material having a high ultrasonic absorption effect, or a wedge processing is performed to perform irregular reflection. However, there has been no effective countermeasure for the multiple reflection between the surface of the phased array probe and the surface of the specimen.

The reverberant ultrasonic signal will be described based on measurement experiment data.
Using the experimental equipment shown in FIG. 10, reverberant ultrasonic data by multiple reflection was collected. In this experimental equipment, a probe unit 2 of a phased array probe 1 and a pipe-shaped test material m0 are fixed to a surface k1 of a rectangular stainless steel plate k. As shown in FIG. 9 (A) above, the phased array probe 1 (the arc presented by the phased array probe 1) is arranged on the surface of the plate k so as to be concentric with the test material m0 at a distance from the test material m0. Fixed.
And it experimented by immersing the said board k with the test material m in flaw detection water (water).
The phased array probe 1 has an arc radius of 52.5 mm and an arc center angle of 60 degrees, and is composed of 128 vibrators arranged at pitch intervals of 0.35 mm at the center. Of these, 32 vibrators vibrate simultaneously. After a series of 32 transducer groups vibrate to emit ultrasonic waves and perform flaw detection, the next 32 transducer groups vibrate and perform flaw detection after shifting several times. The results obtained from the transducer group having the strongest reflection echo are shown in FIGS. 11 (A), 12 (A), and 13 (A).
In the graph shown in each figure, the vertical axis represents the intensity of the reflected echo, and the horizontal axis represents the transverse wave propagation distance (mm) in the test material. The shear wave speed was 3230 m / sec. Since the arrival distance of the sound wave is converted from the arrival time, the distance indicated by the horizontal axis can be considered as time.
The data shown in FIG. 11 (A) shows that the specimen m0 is a pipe having a diameter of 34.0 mm and a wall thickness of 7.0 mm, a refraction angle of 24.6 degrees at the point of incidence of ultrasonic waves on the specimen m0, and a phased array. The sensitivity of probe 1 was obtained as 48.8 dB.
The data shown in FIG. 12 (A) shows that the test object m0 is a pipe having a diameter of 34.0 mm and a wall thickness of 7.0 mm, a refraction angle of 45.0 degrees at the incident point of ultrasonic waves on the test material m0, and a phased array. The sensitivity of probe 1 was obtained as 50.4 dB.
The data shown in FIG. 13 (A) shows that the test object m0 is a pipe having a diameter of 48.6 mm and a wall thickness of 3.7 mm, the refraction angle is 36.8 degrees at the incident point of the ultrasonic wave on the test material m0, and the phased array. The sensitivity of probe 1 was obtained as 51.2 dB. 11A and 13A, the echo height of the 0.1 mm notch flaw on the inner surface and the echo height of the 0.1 mm notch flaw on the outer surface are shown in FIG. The sensitivity was 4/5 (80%) on the vertical axis.
The peaks of the waveforms shown in FIGS. 11 to 13 indicate multiple reflections between the phased array probe surface and the test material surface, that is, reflection echoes between the phased array probe surface and the test material surface. Yes.

Assuming that the S / N ratio is 12 dB, the time (distance) until the peak of the multiple reflection echo decays to 1/5 (20%) or less of the vertical axis is shown in FIG. 11A. In addition, approximately 350 mm (horizontal axis) is required, and when the result shown in FIG. 12A is viewed, approximately 250 mm is required, and when the result illustrated in FIG. 13A is viewed, approximately 300 mm is required. In the case of 350 mm (L), which is the largest value, when converted to time, it is 218 μsec (T) (if the velocity of sound V = 3230 m / sec, T = 2 * L / V). This is the upper limit of the ultrasonic repetition period. In terms of the ultrasonic repetition frequency, it is about 4 KHz. In such a range, even if a defect echo is included, it is difficult to discriminate because it is hidden by the multiple reflection echo.
Therefore, as shown in the experimental results, in actual flaw detection, it is necessary to wait until the ultrasonic echo multiple reflection is attenuated until the defect echo can be discriminated, and then the next pulse is issued. The length of the reverberation time described above hinders the speed of flaw detection.

The inventor of the present application, after earnest research, makes the center of the test material coincide with the arc-shaped array center as in the past, and the reverberation time due to multiple reflections between the phased array probe surface and the test material surface ( It was discovered that the time until the amplitude was attenuated to such an extent that a defect could be detected is a factor that increases the time.
Therefore, the inventor of the present application does not make the center of the arc-shaped array probe coincide with the center of the test material, that is, decenters it, so that at least the multiplexing between the phased array probe surface and the test material surface is performed. It was found that reflection (amplitude) can be reduced and the reverberation time can be greatly reduced.

  In the above Patent Documents 2 and 3, the focus of the ultrasonic wave generated by each of the phased array probes surrounding the outer peripheral surface of the test material, which is a round bar, is used for the purpose of avoiding an undetected area. Some are decentered from the center (axis) of the sample. For example, Patent Document 3 describes that the focus F is displaced with respect to the center O of the test material in order to prevent the occurrence of an undetected area.

  However, in any of the methods shown in these documents, each phased array probe is physically arranged so as to be concentric with the test material, and only the focus of the probe is at the center of the test material. Therefore, the above-mentioned problem of multiple reflection is still not solved in Patent Documents 2 and 3 described above.

  Therefore, the inventor of the present application has solved the above problem by providing a method for reducing multiple reflections between the surface of the phased array probe and the surface of the test material.

The first invention of the present application is provided with a plurality of phased array probes 1... 1 each having an arc of the same radius so as to surround the outer peripheral surface of a columnar or cylindrical sample m, Each of the phased array probes 1... 1 provides an ultrasonic flaw detection method in which a plurality of transducers 10.
That is, each phased array probe 1... 1 is bisected to equally divide the central angle of the arc presented by the phased array probe 1 on a plane (virtual plane) intersecting the axial direction of the test object m. An offset is made with respect to the test material m so as to give an eccentric distance d between the virtual line) and the center of the test material m.
Here, the eccentricity refers to a deviation between a bisector (virtual line) that equally divides the central angle of the arc presented by the phased array probe 1 and the center of the material m to be examined. Accordingly, the eccentric distance is the length of a perpendicular line (imaginary line) drawn from the center of the test material m to the bisector (virtual line), and offset means that the bisector is on the bisector. This means that the phased array probe is shifted and arranged with respect to the test material so as not to pass through the center of the test material m.
In addition, said bisector is also a line | wire which equally divides the line segment which connects the both ends of the arc which the phased array probe 1 exhibits.

  In the second invention of the present application, in the first invention of the present application, the eccentric distance d is smaller than the radius of the test material m and is 1/20 to 1/5 of the radius of the arc exhibited by the phased array probe 1. An ultrasonic flaw detection method is provided.

  In the third invention of the present application, the ultrasonic flaw detection method according to the first or second invention of the present application, wherein the eccentric distances d of the phased array probes 1... 1 are all the same. I will provide a.

In the fourth invention of the present application, a plurality of phased array probes 1... 1 exhibiting arcs of the same radius are provided, and each of the phased array probes 1 is an ultrasonic wave in which a plurality of transducers 10. The following are provided for the flaw detector.
That is, each of the phased array probes 1 is arranged along the circumferential direction of the central axis with respect to the central axis (imaginary line) equal in distance from all the phased array probes 1. Each phased array probe 1 is offset with respect to the central axis so as to have an eccentric distance d between the bisector (imaginary line) that equally divides the central angle of the arc to be presented and the central axis. Features.

  According to a fifth invention of the present application, in the fourth invention, a cylindrical body capable of passing a columnar or cylindrical specimen inside and a specimen to be passed are concentric. Each of the above-described phased array probes 1... 1 is disposed on the inner peripheral surface of the cylindrical body at a different position in the axial direction of the cylindrical body. An acoustic flaw detection apparatus is provided.

In each invention of the present application, the multiple reflection (reverberation) between the surface of the phased array probe and the surface of the test material is attenuated easily and quickly by devising the arrangement of the physical phased array probe. That is, between the center of each phased array probe (the circle to which the arc represented) and the center of the material to be measured accurately, the arc exhibited by the phased array probe during the incidence of ultrasonic waves from the probe to the material to be tested. The reverberation time is set by setting an eccentric distance between the bisector that equally divides the center angle of the sample and the center of the specimen (so that the center of the specimen does not come on the bisector) Was shortened.
In the present invention, even when the flaw detection conditions (for example, longitudinal wave flaw detection, transverse wave flaw detection selection, refraction angle, depth of focus, etc.) in the test material are the same, the phased array introductory data (for example, The transmission pulse delay amount, the reception signal delay amount, the ultrasonic propagation distance from the probe to the ultrasonic incident point of the test material, etc. for each element are different. However, the curved parallelism between the general phased array probe surface and the test material surface (constant physical distance at each part of the probe surface and the test material surface) was reduced, and the multiple reflection was reduced. (Assumed to decay early).
For example, in the conventional method (the method of arranging the phased array probe concentrically with the specimen), the ultrasonic repetition frequency is limited to about 4 kHz (about 2 kHz is practical considering material deformation and eccentricity). By implementing this invention, the ultrasonic repetition frequency can be increased to about 8 kHz.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 to 8 show an embodiment of the present invention. FIG. 1 is a schematic overall longitudinal sectional view showing an embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view of a main part (first flaw detection part 100a) of the flaw detection apparatus shown in FIG. FIG. 3 is an explanatory diagram showing a state in which the apparatus shown in FIG. 2 is viewed from the front. FIG. 4 is a schematic longitudinal sectional view of a main part (second flaw detector 100b) of the flaw detector shown in FIG. FIG. 5 is an explanatory view showing a state in which the apparatus shown in FIG. 4 is viewed from the front. 6A is a front view of the probe unit 2 of the phased array probe 1 used in the apparatus shown in FIGS. 1 to 5, and FIG. 6B is a side view thereof. FIG. 7 shows a schematic front view of the ring 3 to which the probe unit 2 shown in FIG. 6 is attached. FIG. 8 is an explanatory diagram of the ring 3 shown in FIG. 3 and 5, the test material m is omitted.
For convenience of explanation, in the drawings, U is appropriately upward, S is downward, F is forward (advancing direction of the test material m), and B is backward.

As shown in FIG. 1, the ultrasonic flaw detector according to the present invention includes two flaw detectors (a first flaw detector 100a and a second flaw detector 100b).
This flaw detector detects flaws in a steel pipe (pipe) or billet to be a test material m, and in such a steel pipe manufacturing process or processing process, flaw detection is performed during the movement of the steel pipe. That is, the flaw detection device is arranged in the middle of the transfer path of the steel pipe that is transferred by the feeding device included in the steel pipe manufacturing / processing apparatus, and the flaw detection of the steel pipe is performed. The feeding device transports the test material m along the axial direction, and does not rotate the test material m. That is, the test material m is only moved linearly, and is not displaced in the circumferential direction. As shown in FIG. 1, the test material m is linearly fed from the rear B side toward the front F.
The transfer in the axial direction is a relative movement with respect to the flaw detection apparatus, and can also be implemented as a flaw detection apparatus (probe) that moves linearly along the axial direction of the material to be examined m.

Hereinafter, the configuration of each part of the flaw detector will be described in detail.
Each of the flaw detection parts 100a, 100b includes a plurality of probe units 2 ... 2 (FIGS. 6A and 6B), a plurality of rings 3 ... 3 (FIG. 7), and end rings 4 ... 4 (FIG. 1, 2 and 4), a plurality of bushes 5... 5, a ring support body 6, a bush holding body 50 (FIGS. 1 to 5), and a locking tool 7.
The first flaw detection part 100a (FIGS. 2 and 3) and the second flaw detection part 100b (FIGS. 4 and 5) differ in the number of rings 3 (as shown in FIG. 4, the second flaw detection part 100b is the first flaw detection part). The number of the single ring 3 is larger than that of the part 100a.) Further, only the direction of the rings 3 ... 3 with respect to the test material m is different, and the other configurations are the same. Therefore, hereinafter, the first flaw detection unit 100a will be described as a representative of both flaw detection units.

As the probe unit 2, an existing unit shown in FIGS. 6A and 6B can be adopted. As shown in FIG. 8, each probe unit 2 (hereinafter simply referred to as “unit 2” if necessary) includes a phased array probe 1 having a plurality of transducers 10... 1) is provided. In this embodiment, one probe 1 includes 128 transducers 10. The transducers 10... 10 transmit and receive ultrasonic waves and are electrically connected to a transmission circuit and a reception circuit (not shown). In FIGS. 1-6, 11 has shown the conducting wire which bears the connection with the said circuit. The transmission circuit is a circuit that applies a pulse voltage necessary for transmission (vibration) of ultrasonic waves to the vibrator 10 at a predetermined timing. The receiving circuit is a circuit that converts the ultrasonic wave (reflected wave) received by the transducer 10 into an electric signal and performs signal processing. Both the transmission circuit and the reception circuit can be implemented by employing a conventionally known circuit.
In this embodiment, each probe 1 vibrates 32 vibrators out of 128 in one flaw detection. Then, the vibrator to be vibrated is shifted by several, and the next 32 are vibrated. This sequence is repeated.
As shown in FIG. 6, the unit 2 is a plate-like body (cube), and the probe 1 is provided at the tip. That is, the tip of the unit 2 exhibits an arc.

As shown in FIG. 7, each ring 3 is a disk, ie, an annular body, having a hollow portion 30 penetrating the front and back.
The rings 3... 3 are overlapped so as to be concentric and are stopped by a locking tool 7 (FIGS. 1, 2, and 4). Thus, the rings 3 ... 3 form one cylindrical body (corresponding to the cylindrical body of claim 5 of the claims). In this embodiment, the locking tool 7 is a bolt provided with a nut (hereinafter referred to as a bolt 7).

Each of the rings 3 ... 3 is formed with a receiving portion 21 to which the probe unit 2 is attached.
The receiving portion 21 is a recess formed in the end surface of the ring 3. The receiving portion 21 is a concave portion having an internal shape and size corresponding to the shape and size of the unit 2, and exactly fits the receiving unit 2.
The unit 2 is fitted into the receiving portion 21 and the unit 2 is fixed to the ring 3 with a fixing tool such as a screw or a bolt. However, it is also possible to fix the unit 2 to each ring 3 by fixing the rings 3... 3 with the bolts 7 instead of fixing to the rings 3 using such a fixture. is there. The receiving part 21 communicates with the hollow part 30 of the ring 3, and the probe 1 of the unit 2 attached faces the hollow part 30 of the ring 3.
By forming one receiving portion 21 in one ring 3, one unit 2 can be provided for one ring 3. However, it is also possible to provide a plurality of receiving units 21 in one ring 3 and a plurality of units 2. For example, the present invention can be implemented by forming the receiving portions 21 on both sides of the disk-shaped ring 3.
In this embodiment, one unit 2 is provided in one ring 3 except for the support plate 62 of the next support 6.

As shown in FIG. 2 (FIG. 3), the ring support 6 includes a base 61 that is installed and fixed on the ground or floor, and a support plate 62 that is erected on the upper surface of the base 61. The support plate 62 is a plate-like body that extends vertically, and includes a through portion 63 that penetrates in the front-rear direction. The support plate 62 is overlaid on the rings 3... 3 and is bolted together with the bolts 7 together with the rings 3. At the time of bolting, the front and back of the support plate 62 are stopped between the rings 3.
In the above, the support plate 62 is overlapped with the rings 3... 3 and bolted so that the through-hole 63 of the support plate 62 corresponds to the hollow portion 30 of the rings 3. Specifically, the bolts 7... 7 pass through all the rings 3... 3, the support plate 62, the end rings 4 and 4, and the bush holders 50 and 50. The end rings 4 and 4 and the bush holders 50 and 50 are fixed together.
Thus, the rings 3... 3 (and the end rings 4, 4 and the bush holding bodies 50, 50) are held by the ring support 6 with their axial directions being horizontal.
In this embodiment, two probes 1 (units 2) are attached to the support plate 62 so as to face the inside of the penetration part 63. In other words, the receiving portion 21 of the (two) units 2 is also provided on the support body 62, and the unit 2 is attached to the receiving portion 21. Hereinafter, the penetrating portion 62 of the support plate 61 will be described as one of the hollow portions 30 in the same manner as the other rings 3.

As described above, when the bolts of the rings 3... 3 are bolted, the end rings 4 and 4 are fastened together with the bolts 7 on both end faces of the cylinder exhibited by the stacked rings 3. Each of the rings 3... 3 is sandwiched between the ring support 6 and the rings 4 and 4 at both ends (FIGS. 2 and 4).
As shown in FIGS. 1 and 2 (FIG. 4), the ring 3... 3 and the hollow portion 30 of the support plate 62, the end rings 4 and 4 and the center of each bush 5... 5 (hollow portions 40 and 50) A test material m is passed.

  As for the cross-sectional shape of the inner peripheral surface (hollow portion 30) of the rings 3 ... 3, the entire shape is not a perfect circle. However, as will be described later, on the inner peripheral surface, on the portion other than the arc exhibited by the probe 1 It has a part (FIG. 8) which becomes a perfect circle (in addition to the part where the unit 2 is provided). The rings 3... 3 are arranged so that the portion that becomes a perfect circle is concentric with the test material m. The same applies to the support plate 62.

Specifically, in this embodiment, the rings 3... 3 are all disks having the same outer diameter, and the thicknesses (the widths between the front and back end faces) are all the same (for the support plate 62, the unit Since two 2 can be attached, the thickness is larger than that of the rings 3.
The probe 1 faces the hollow portion 30 of the ring 3 from the inner peripheral surface of the ring 3, and the arc that the probe 1 exhibits belongs to a plane (virtual surface) orthogonal to the axial direction of the test object m, The unit 2 is attached to the ring 3.
Said receiving part 21 is a recessed part provided in the end surface of the ring 3 according to the outer diameter of such a unit 2. FIG.

Each of the bushes 5 ... 5 is an annular member, and is disposed on the opposite side of the rings 3 ... 3 with the end rings 4 ... 4 interposed therebetween, and is held by the bush holders 50, 50. In this embodiment, a total of six bushes 5... 5 are disposed in front of and behind the rings 3. However, the number of the bushes 5 is not limited to such a number and can be changed.
The cross-sectional shape of the hollow portion 40 of the end ring 4 and the inner peripheral surface (hollow portion 50) of the bush 5 is a circle. In the above, the end rings 4, 4 and the bushes 5, 5 are arranged and fixed so that the hollow portions 40, 50 are concentric with the specimen m. That is, the end rings 4 and 4 are attached to the rings 3 and 3 so that the hollow portion 40 is concentric with the test material m, and the bush holding bodies 50 and 50 are connected to the hollow portion 50 and the ring 3. The bushes 5... 5 are held so that 3 is concentric.
Each bush 5... 5 guides the material m to be sent. In this embodiment, the inner diameters of at least some of the bushes 5a, 5a (the diameter of the hollow portion 50) are smaller than the inner diameters of the other bushes 5 ... 5 (the diameter of the hollow portion 50). The inner peripheral surface corresponds to (belongs to) the outer periphery of the test material m, and the bushes 5 and 5a are used to center the test material m (which tends to be bent during transfer and cause runout) Positioning).
The support member according to claim 5 includes the rings 3... 3, end rings 4... 4, bushes 5... 5, bush holders 50. And the locking tools 7.

  As shown by dotted lines in FIG. 7, flaw detection water supply sections 32 are provided inside each ring 3. The water supply portions 32 and 32 are passages for introducing flaw detection water from the outside to the hollow portion 30. In FIG. 7, the positioning part 31 is omitted in order to avoid complication of the drawing. Moreover, in FIGS. 1-5 and FIG. 8, about the said water supply parts 32 and 32, it has abbreviate | omitted and drawn). The water supply units 32 and 32 supply flaw detection water during flaw detection. The flaw detection water supplied into the hollow portion 30 is discharged outside through the clearance between the bushes 5... 5 and the test material m. However, the water supply unit 32 may be provided not only on each ring 3 but only on a part of the rings 3 and the support 62. Further, the drainage can be carried out by forming a separate drainage passage in a part of the ring 3 or the support body 62 instead of relying exclusively on the clearance between the bushes 5... 5 and the test material m. It is.

The arrangement of the units 2 ... 2 will be described in detail.
First of all, all the units 2 ... 2 have the following relationship. That is, in the unit (2, 2) adjacent to each other in the axial direction of the test material m, the probes 1 exhibiting an arc are placed on a plane (virtual plane) orthogonal to the center line (virtual line) of the test material m. The center of the test material m is sequentially shifted by a predetermined angle in the same direction (for example, clockwise in a front view from the front side). This means that the arrangement between the probes 1... 1 finally satisfies such a standard). That is, as shown in FIG. 8, in the (virtual) plane that intersects the axial direction of the test material m, the individual probes 1 have different directions from each other around the center M of the test material m ( In FIG. 8, the test material m is not shown. In this embodiment, the central angle of the arc presented by the probe 1 is 60 degrees. And between the adjacent probes 1, it has a shift | offset | difference (deviation angle) of 25.7 degrees centering on the center M of the to-be-tested material m.
Regarding the above-described deviation angle, bisectors that bisect (angle θ) the central angle φ of the arc presented by each probe 1 are formed on a (virtual) plane that intersects the axial direction of the specimen m. Think of it as an angle.
In this way, the orientations of the probes 1... 1 are determined so as to be shifted by a predetermined angle (25.7 degrees in this embodiment).
In this way, by shifting the probes 1... 1 by a predetermined angle, the outer periphery of the test material is covered 360 degrees.

  Secondly, for each of the probes 1... 1 having different directions as described above, in the (virtual) plane orthogonal to the axial direction of the test object m, each of the probes 1. The line is arranged in a state with a predetermined interval (eccentric distance d) with respect to the center of the test material m.

Each of the probes 1... 1 is fixed to the flaw detection unit so that the probes 1... 1 take the first orientation and the second arrangement.
As long as each probe 1 satisfies the above orientation and arrangement, it is not particularly limited to adopting the above rings 3... 3, but to the rings 3. By attaching, the above orientation and arrangement can be easily realized.

Hereinafter, a method for installing the probes 1... 1 will be specifically described.
In this embodiment, the receiving portions 21... 21 of the rings 3... 3 are provided on the end face of the ring 3 at positions and orientations where the receiving unit 2 takes the following arrangement (and orientation).
When the arc of the probe 1 (presented) is arranged concentrically with the center of the specimen m, the bisector (virtual line) that bisects the central angle of the arc is that of the specimen m. It passes through the center (hereinafter, the bisector passing through the center of the specimen m is referred to as a center inclusion line t2). The bisector of the arc presented by the probe 1 is parallel to the center inclusion line t2, and is parallel to the center inclusion line t2 by a predetermined distance (eccentric distance d) (virtual line / necessary below) Accordingly, the unit 2 is arranged so as to be referred to as an offset line t1. If the unit 2 is fitted, the receiving portion 21 may be formed in the ring 3 so as to adopt the above arrangement.
The position of the receiving portion 21 is based on the position of the probe 1 that does not take the eccentric distance d (the probe 1 is concentric with the center M of the specimen m), that is, according to claim 4 of the claims. Along a straight line (hereinafter referred to as an arc end line t3) connecting arc ends p1 and p2 of the probe 1 at the position with reference to a central axis equal in distance from all the phased array probes (the arc end line) It is preferable that the unit 2 is arranged so that the probe 1 is positioned closer to one arc end (by an eccentric distance d) (on the extension line of t3) (even after the eccentric distance d is set). It is preferable that the unit 2 is arranged so that is located on the extension line of the arc end line t3). However, the arrangement is not limited to such an arrangement as long as the center M of the specimen m is not positioned on the center inclusion line t2. In other words, any bisector having an eccentric distance is acceptable, and the bisector is not limited to one that moves so that the arc end of the probe is positioned on the arc end line.
In this flaw detection apparatus, the center M (center axis) of the test object coincides with the center axis that equalizes the distance from all the phased array probes.

The magnitude of the eccentric distance d is set to 1/20 to 1/5 of the radius of the arc presented by the probe 1. In this embodiment, the radius of the arc presented by the probe 1 is 52.5 mm, and an eccentric distance of 5 mm is set.
When the center inclusion line t2 extends vertically (extends in the vertical direction) when the front end (front surface) of the test object m is viewed from the front, the eccentric distance d is set to the right of the center inclusion line t2. Alternatively, it may be set to the left side.
As described above, in one flaw detection apparatus, the size of the material to be inspected is not limited to such one size. That is, one flaw detection device can be used as long as it can pass through the flaw detection device and can secure a necessary water distance (distance between the surface of the probe 1 and the surface of the object m, that is, the width of flaw detection water interposed). The dimensions of the material m to be inspected are not unambiguous.
In this embodiment, the sample m is exemplified as having a diameter (outer diameter) of 50 mm. By setting the eccentric distance d, the water distance is not constant at each position (each transducer 10... 10) of the probe 1 (this realizes early attenuation of multiple reflection).

Assuming that the cross-sectional shape of the entire inner peripheral surface of the ring 3 (excluding the probe 1) is a perfect circle, the probe 1 is arranged so as to have an eccentric distance d as described above. On the orthogonal plane, a step is generated between the probe 1 (the arc end thereof) and the other part of the inner peripheral surface of the ring 3. Such a step is not preferable because it becomes a reflection source of ultrasonic waves.
For this reason, each part of the inner peripheral surface of the ring 3 is formed in a curve so that there is no step between the probe 1 and the other part of the inner peripheral surface of the ring 3.
For example, the cross-sectional shape of the inner peripheral surface of the ring 3 is preferably the shape shown in FIG. 8 (the test material m is omitted in FIG. 8). In this case, the center of the arc presented by the probe 1 is on the aforementioned offset line t1. Here, for convenience of explanation, a line t4 (hereinafter referred to as a parallel center line t4) parallel to the arc end line t3 connecting the arc ends p1 and p2 of the probe 1 and passing through the center M of the m of the test material. A circle centered on the center M of the test material m (as described above, in this embodiment, in order to ensure the necessary water distance, a circle with a radius of 52.5 mm for a test material having a diameter of 50 mm) and The intersecting points are defined as intersection points p3 and p4.

On the opposite side of the probe 1 across the parallel center line t4, the inner periphery of the ring 3 is formed so as to coincide with the circle (center M). In other words, the inner peripheral surface of the ring 3 on the side opposite to the probe 1 across the parallel center line t4 is an arc with the intersections 3 and p4 as arc ends and is formed to be a part of a perfect circle (described above) It is the part that becomes a perfect circle).
On the opposite side of the inner circumferential surface of the ring 3 from the arc, there is a concave curve with no step between the arc end p1 and the intersection point p4 and between the arc end p2 and the intersection point p3. ). Any concave curve can be implemented as long as it is curved without a step. Moreover, the range which becomes a perfect circle is not limited to the above. Moreover, it may not have a part that becomes a perfect circle.
Further, although the eccentric distance d is set as described above, a step is formed on the inner peripheral surface between the adjacent rings 3 and 3, but the ultrasonic wave does not spread in the thickness x direction of the probe 1 (FIG. 6B). (Although it actually spreads slightly, it does not widen to the extent that the level difference in the axial direction of the specimen m becomes a problem), so it can be ignored.

In this embodiment, the unit 2 is a ready-made product. In the ready-made product, the center angle φ of the arc exhibited by the probe 1 is not limited to 60 degrees as described above. However, it is necessary that the arc end line t3 and the parallel center line t4 do not coincide with each other. From such a point, the center angle φ needs to be smaller than 180 degrees.
More realistically, it is preferable that the arc end line t3 does not intersect the specimen m. In general, the center angle φ is preferably 120 degrees or less in consideration of the diameter and water distance (distance between the probe and the surface of the test material) of the target test material m.
In consideration of the size and number of transducers 10 of the probe 1 that can be used, the central angle is preferably 8 degrees or more and 100 degrees or less.
However, the center angle φ of the probe 1 is not limited to the above numerical range.

In this embodiment, as shown in FIGS. 3 and 5, at least each of the bolted rings 3... 3 is fixed in a state shifted by a predetermined angle with respect to the adjacent ring 3 in the circumferential direction R. . That is, the holes through which the bolts 7 provided in the individual rings 3 are respectively provided at the positions shifted from the predetermined angle and fixed through the bolts 7, so that the adjacent fed-array probes 1, 1 are The above deviation can be provided. In this embodiment, the deviation angle is 25.7 degrees as described above. However, such numerical values can be changed.
Moreover, as shown to FIG.2 and FIG.4, unevenness | corrugation is provided as the positioning part 31 in the end surface of each ring 3 ... 3, and the said shift | offset | difference is fitted by fitting the said positioning part 31 of adjacent rings 3 and 3 mutually. Can be determined accurately. In this embodiment, a pin is attached to the ring as the uneven convex portion.
By attaching the rings 3... 3 in a shifted manner in this way, the probes 1 (units 2) provided on the individual rings are arranged in a state where the predetermined angles are shifted.
1, 2, and 4, in order to avoid the complexity of the drawings, such a positional relationship in the circumferential direction between the rings 3... 3 is not drawn (supported by the support plate 62. The unit 2 is drawn except that it is arranged in the same direction except for a part of the unit 2, but in reality, the rings 3 ... 3 are arranged with the above-mentioned angles shifted, This is different from what I draw.

  For each of the rings 3... 3, the shape of the hollow portion 30 is the same, and the mounting position of the probe 1 is the same with respect to the hollow portion 30, but each has a difference in orientation in the circumferential direction of the test material M. , The positions of the holes through which the bolts 7...

  As described above, the units 2... 2 have different directions on the plane that intersects the axial direction of the test material m around the test material m according to the first standard. If the distance is not set), it is arranged in the same plane so that a part of the arc overlaps between the adjacent probes 1 and 1 (actually the eccentric distance is set, so the front F or When the probes 1... 1 are seen through from the rear B, the arcs of the probes 1... 1 do not overlap each other even if they intersect each other. Each unit 2 ... 2 is drawn ignoring the distance).

The operation of the probe 1 will be described.
Usually, not all the vibrators constituting one probe 1 are vibrated at the same time, but some vibrators are sequentially shifted by a predetermined number to vibrate. In this embodiment, 32 of the 128 vibrators are vibrated simultaneously. After a series of 32 vibrators vibrate to emit ultrasonic waves and perform flaw detection, a few shifts occur and 32 vibrators vibrate to perform flaw detection. Repeat this.
A specific description will be given assuming that the number of shifts is five.
When the vibrators 10... 10 arranged in an arc shape of one unit 2 (probe 1) are named as No. 1, No. 2, No. 127, No. 128 from the end, the first transmission voltage is received and 1 to 2. The 32nd vibrator 10... 10 emits an ultrasonic wave, then the 5th to 6th to 37th vibrators 10... 10 emit the ultrasonic wave, and the 5th shifted 11th to 42th vibrators 10. ... 10 generates ultrasonic waves. Such a shift is sequentially performed to detect each part of the specimen m.
By setting the eccentric distance, shortening the reverberation time of the ultrasonic wave (accelerating the attenuation of the echo) can accelerate the start of the operation of the next transducer group due to the shift described above.
That is, the time from the vibration of 32 vibrators to the vibration of the next 32 vibrators has been shortened by implementing the present invention.

For each of the probes 1... 1 (units 2... 2), the first, second,..., 15 are named from the rear B side toward the front F side along the axial direction of the test object m. The detected material m is subjected to flaw detection in order in the axial direction from the first probe 1a to the second probe 1b, the third probe 1c,... 1 to 15 probes 1... 1 (unit 2... 2) are used, of which the first to seventh probes are provided in the first flaw detection unit 100a, and the eighth to fifteen probes are provided in the second flaw detection unit 100b. Is).
The flaw detection is performed in order from the first probe (from back to front) between the units 2. However, in the above, after the operation of the 128th transducer of the first probe 1 is completed due to the shift of the transducer, the first probe operates instead of operating the 1-32 transducers of the second probe. After starting, the transducer of the second probe is operated before the last transducer of the first probe is operated. For other probes, the transducer of the subsequent probe is operated after the operation of the preceding probe is started and before the last transducer of the preceding probe is operated.
However, the probes 1... 1 (units 2... 2) are separated from each other by a considerable distance in the axial direction, and flaw detection is possible at the same time. Therefore, unlike the above, for example, at the timing when the transducers 1 to 32 of the first probe transmit ultrasonic waves, the transducers 1 to 32 of the other probes can simultaneously transmit ultrasonic waves. is there. At this time, the transmission vibrator number group of the first probe and the transmission vibrator number group of the other probes are not necessarily the same.

In this embodiment, the first flaw detection unit 100a includes seven units 2... 2 and the second flaw detection unit 100b includes eight units 2. However, the number of such units 2, that is, the number of probes 1 ... 1 can be changed. Accordingly, the number of rings 3... 3 can be changed. The angle shifted between the rings 3 and 3 (shift angle) is not limited to the above, and can be changed to an angle other than 25.7 degrees. For example, the deviation angle can be changed in accordance with the change in the center angle of the arc presented by the probe 1 or the number of units. In the above description, a prefabricated product having an arc center angle of 60 degrees is used as the probe 1, but the center angle of the probe is not limited to such an angle.
In the above description, the number of transducers 10... 10 included in one probe 1 is 128. However, the number is not limited to this number, and other numbers can be used. Further, the number of vibrators 10... 10 that vibrate simultaneously is not limited to the above-mentioned 32, and can be changed. Further, the number of vibrators that shift to the next vibration after the vibration is not limited to the above five but can be changed.

In this embodiment, the two flaw detection parts, ie, the first flaw detection part 100a and the second flaw detection part 100b, share the outer periphery 360 degrees of the test object m. However, the number of flaw detection parts is not limited to two, and can be one or three or more.
In the above description, the probes 1... 1 of the flaw detector cover all 360 degrees of the outer periphery of the test material. However, this is not the case. For example, the probes 1... 1 of the flaw detection apparatus can cover a range smaller than 360 degrees, and the range not covered can be implemented by performing flaw detection by a separate means. is there.
Further, the present invention can be carried out even if the probes 1... 1 are arranged beyond the above 360 degrees (overlapping).
In the above embodiment, the flaw detection water is supplied from the outside and discharged (running water). However, it can also be carried out by a submersion type, that is, the apparatus is submerged in water.
In said embodiment, the said flaw detection apparatus is arrange | positioned in the middle of the transfer path | route of the steel pipe (test material m) transferred by the feeder with which the manufacturing and processing apparatus of a steel pipe (test material m) is equipped, The steel pipe (test material m) was to be flaw-detected. In addition, the flaw detection apparatus may be provided with a feeding device. In that case, flaw detection of the steel pipe (test material m) can be performed separately from the manufacturing and processing steps.

With respect to the experimental equipment shown in FIG. 10 described above, a reverberant ultrasonic measurement experiment was performed with the eccentric distance set. Data obtained by the experiment is shown in FIGS. 11B, 11C, 12B, 13C, and 13C.
All were performed under the same conditions as those shown in FIGS. 11 (A), 12 (A), and 13 (A) except for the test material for which the eccentric distance was set.
That is, in the data shown in FIGS. 11B and 11C, the specimen m0 is a pipe having a diameter of 34.0 mm and a wall thickness of 7.0 mm, and the refraction angle of the ultrasonic incident point on the specimen m0 is 24. The sensitivity of the phased array probe 1 was 68.8 degrees and was obtained as 48.8 dB. The data shown in FIGS. 12B and 12C show that the specimen m0 is a pipe having a diameter of 34.0 mm and a thickness of 7.0 mm, and the refraction angle is 45.0 degrees at the incident point of the ultrasonic wave on the specimen m0. The sensitivity of the phased array probe 1 was obtained at 50.4 dB. The data shown in FIGS. 13B and 13C show that the specimen m0 is a pipe having a diameter of 48.6 mm and a wall thickness of 3.7 mm, and the refraction angle at the incident point of the ultrasonic wave on the specimen m0 is 36.8 degrees. The sensitivity of the phased array probe 1 is 51.2 dB.
In the above, with respect to the center inclusion line t2 (which extends vertically), the offset to either the left or right is + (positive), and the offset to either the left or right is-(negative) (data is The positive and negative are set in this way for the convenience of specifying the collected position). In FIGS. 11B and 12B, the eccentric distance d is +5 mm. In FIGS. 11C and 12C, the eccentric distance d is −5 mm. In FIG. 13B, the eccentric distance d is set to +4 mm. In FIG. 13C, the eccentric distance d is set to -4 mm.

11B and 11C, in both cases, the echo peak is attenuated within 150 mm on the horizontal axis and 1/5 or less (within 1 square) of the vertical axis (5 squares) (FIG. 11). (C) converges to 1/5 or less within 100 mm). The time (distance) required for the peak of the multi-reflection echo to decay to 1/5 or less of the vertical axis is significantly lower than the 350 mm required when no eccentric distance is provided (FIG. 11A). It can be seen.
Similarly, in FIGS. 12B and 12C, in both cases, the echo peak is attenuated within 150 mm on the horizontal axis and 1/5 or less (within 1 square) of the vertical axis (5 squares) ( In FIG. 12C, it converges to 1/5 or less within 100 mm). The time (distance) required for the peak of the multi-reflection echo to attenuate to 1/5 or less of the vertical axis is significantly lower than the 250 mm required when no eccentric distance is provided (FIG. 12A). It can be seen.
Similarly, when looking at FIGS. 13B and 13C, the echo peak is attenuated within 200 mm on the horizontal axis and within 1/5 of the vertical axis (5 squares) (within 1 square). (In FIG. 13C, it converges to 1/5 or less within 100 mm). The time (distance) required until the peak of the multi-reflection echo attenuates to 1/5 or less of the vertical axis is significantly lower than the 300 mm required when no eccentric distance is provided (FIG. 13A). It can be seen.
In the case of 200 mm (L), which is the longest time required for the echo peak to decay below the vertical axis 1/5, when converted to time, it becomes 124 μsec (T) (sound speed V = 3230 m / If it is set to sec, T = 2 * L / V.) This is the upper limit of the ultrasonic repetition period. In terms of the ultrasonic repetition frequency, it is about 8 KHz.
From these experimental results, it can be seen that the setting of the eccentric distance is extremely effective in reducing the multiple reflection echo.

It is a substantially whole longitudinal cross-sectional view which shows one embodiment of this invention. FIG. 2 is a schematic longitudinal sectional view of a main part (first flaw detection unit 100a) of the flaw detection apparatus shown in FIG. It is explanatory drawing which shows the state which looked at the apparatus shown in FIG. 2 from the front. It is a schematic longitudinal cross-sectional view of the principal part (2nd flaw detection part 100b) of the flaw detection apparatus shown in FIG. It is explanatory drawing which shows the state which looked at the apparatus shown in FIG. 4 from the front. (A) is the front view of the probe unit 2 of the phased array probe 1 used for the apparatus shown in FIGS. 1-5, (B) is the side view, (C) is the principal part explanatory drawing. . The schematic front view of the ring 3 which attaches the probe unit 2 shown in FIG. 6 is shown. It is explanatory drawing of the ring 3 shown in FIG. (A) And (B) is explanatory drawing which shows the flaw detection method using the conventional phased array probe 1. FIG. It is a front view of the experimental equipment which measures the reverberation echo of the conventional flaw detector according to the present invention. (A) is explanatory drawing which shows the conventional result obtained with the equipment shown in FIG. 10, (B) and (C) is explanatory drawing which shows the effect of this invention similarly obtained with the equipment shown in FIG. It is. (A) is explanatory drawing which shows the conventional result obtained with the equipment shown in FIG. 10, (B) and (C) is explanatory drawing which shows the effect of this invention similarly obtained with the equipment shown in FIG. It is. (A) is explanatory drawing which shows the conventional result obtained with the equipment shown in FIG. 10, (B) and (C) is explanatory drawing which shows the effect of this invention similarly obtained with the equipment shown in FIG. It is.

Explanation of symbols

1 Phased array probe 10 Oscillator d Eccentric distance m Test material

Claims (5)

A plurality of phased array probes each having an arc of the same radius are provided so as to surround the outer peripheral surface of a columnar or cylindrical specimen, and the specimen is inspected. In the ultrasonic flaw detection method in which a plurality of transducers are arranged in an arc shape,
Eccentric distance between the bisector that divides each phased array probe equally in the center angle of the arc that the phased array probe presents on the plane that intersects the axial direction of the test material, and the center of the test material The ultrasonic flaw detection method is characterized by offsetting the test material so that the   2. The ultrasonic flaw detection method according to claim 1, wherein the eccentric distance is smaller than the radius of the test material and is 1/20 to 1/5 of the radius of the arc exhibited by the phased array probe.   The ultrasonic flaw detection method according to claim 1, wherein the eccentric distances of the phased array probes are all the same. In the ultrasonic flaw detector comprising a plurality of phased array probes that exhibit an arc of the same radius, each of the phased array probes is a plurality of transducers arranged in an arc shape,
Each of the phased array probes is arranged along the circumferential direction of the central axis with respect to the central axis that is equal in distance from all the phased array probes.
Each phased array probe is offset with respect to the central axis so as to have an eccentric distance between the bisector that equally divides the central angle of the arc presented by each phased array probe and the central axis. Ultrasonic flaw detector. A cylindrical body capable of passing a columnar or cylindrical specimen inside and a support member that supports the cylindrical body so as to be concentric with the specimen to be passed,
5. The ultrasonic wave according to claim 4, wherein each of the phased array probes is disposed at a different position in the axial direction of the cylindrical body on the inner peripheral surface of the cylindrical body. Flaw detection equipment.

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