JP2000283967A - Automatic ultrasonic flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the stop time of an inspection line by moving two angle probes to transmit/receive the ultrasonic wave diagonally in the direction opposite to each other in the horizontal direction opposite to each other, holding them together with a normal probe, and rotating them on an outer peripheral surface of an object. SOLUTION: When a worm 13 projected outward of a probe holder 19 is rotated, a worm wheel shaft 14 is also rotated, and nuts 17, 18 are brought close/away from the axis Y-Y' of an object 1 is line-symmetric manner by a right screw part 16a and a left screw part 16b at both ends. A slide plate having an angle probe 12 is mounted on the nuts 17, 18, respectively, and the deviation X1 is variable according to the rotation of the worm 13. By automatically controlling the rotation of the worm 13, the angle of incidence of the ultrasonic wave incident on the surface of the object 1 from the angle probe 12 is constant. When the size of the object is changed, it is sufficient to rotate the worm 13, and horizontally move the angle probe 12, thereby shortening the time for changing the condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an automatic ultrasonic flaw detector for online inspection of flaws existing in a billet, a bar or the like having a columnar cross section in a steel line. .

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing a probe and a probe holder in a conventional automatic ultrasonic flaw detector. In the drawing, 1 is a test material such as a round bar, 2 is a vertical probe that transmits and receives ultrasonic waves to and from the center of the test material 1, and 3 is a counter-clockwise supersonic diagonal to the surface of the test material 1. A first oblique probe for transmitting and receiving a sound wave, 4 is a second oblique probe for transmitting and receiving an ultrasonic wave obliquely to the surface of the test piece 1 in a clockwise direction, and 5 is a vertical probe 2 for the above. A spacer 6 for attaching the angled probes 3 and 4 is a probe holder for fixing the spacers 5 and 6 at a predetermined position, and a spacer 8 is filled inside the probe holder 7. Couplant consisting of water or the like;
Are located near the center of the specimen 1, 10 is located near the outer surface of the specimen 1, L1 is the vertical probe 2 and the specimen 1
L2 is the distance between the oblique probes 3 and 4 and the surface of the test material 1.

[0003] A conventional automatic ultrasonic flaw detector is configured as shown in FIG. 5. For example, when the outer diameter range of the test piece 1 is from φ18 to φ131, the outer diameter range is set to φ18.
Size range from φ34 to φ34, φ35 to φ7
The range up to 4 is classified as size 2 section, the range from φ75 to φ131 is classified as size 3 section, and the vertical probe 2 is set so as to secure a predetermined S / N within the size section.
And the conditions of the oblique probes 3 and 4 (frequency, transducer size, radius of curvature of the acoustic lens), the distance L1 between the vertical probe 2 and the surface of the test piece 1, and the oblique probes 3, The distance L2 between the sample No. 4 and the surface of the test material 1 is set. Further, in the case where the probe holders 7 having different outer diameters for the respective size sections are provided by the number of the size sections, and the outer diameter dimension of the test material 1 changes within the range of the one size section described above, By exchanging the spacers 5 and 6, the distance L1 between the vertical probe 2 and the surface of the test material 1 and the distance L2 between the oblique probe 2 and the surface of the test material 1 are always kept constant. use. That is, the fact that the distances L1 and L2 are constant within the size section as described above means that, in particular, the pattern of the multiple echoes generated when the ultrasonic wave reciprocates between the vertical probe 2 and the surface of the test material 1 many times. Is roughly determined for each segment,
The repetition frequency of the transmission can be easily determined, and the oblique probes 3 and 4 are set so that the ultrasonic waves can be transmitted and received at a constant angle with respect to the surface of the test material 1.

Next, the propagation of the ultrasonic wave will be described. The ultrasonic wave transmitted from the vertical probe 2 toward the center of the test material 1 passes through the couplant 8 filled in the probe holder 7. The beam reaches the flaw 9 near the center, is reflected again by the reverse route, is received by the vertical probe 2, and is transmitted from the oblique probe 3 via the couplant 8 to a predetermined position on the surface of the test piece 1. The ultrasonic wave transmitted obliquely propagates toward the outer surface of the test material 1 according to Snell's law, reaches the flaw 10 near the outer surface, is reflected again by the reverse path, and is reflected by the oblique probe 3. Is received.

[0005]

In the conventional automatic ultrasonic flaw detector, when the size of the test material 1 changes, the inspection line is changed to replace the probe holder 7 or the spacers 5 and 6. There is a problem that the operation must be stopped for about 30 minutes, and furthermore, a plurality of probe holders 7 and spacers 5 and 6 must be held for each size division, which raises a problem that the price of the apparatus increases. Was.

In addition, there is a problem that the vertical probe 2 is required at least as many as the number of the outer diameters of the test material 1 and the price of the apparatus is increased.

In addition, the oblique probes 3 and 4 are required at least as many as the number of the outer diameter sections of the test material 1, resulting in a problem that the cost of the apparatus is increased.

The present invention has been made in order to solve such a problem, and the outer diameter of the test material is from φ18 to φ18.
One probe holder and one type 1 in the range of 131
The objective is to reduce the downtime of the inspection line that occurs when the outer diameter of the specimen is changed, and to provide an inexpensive device that is composed of two vertical probes and one type of two oblique probes. And

[0009]

In the automatic ultrasonic flaw detector according to the present invention, the two oblique probes are kept at a constant vertical distance from the center of the material to be inspected. A worm wheel shaft provided with a right-hand thread portion and a left-hand thread portion for moving the center position of the tentacle in a direction opposite to each other in the horizontal direction with respect to the center of the test material, and a right-hand thread portion of the worm wheel shaft. A first nut to be joined;
A second nut coupled to the left thread portion;
A slide plate coupled to each nut of
Two angle beam probes fixed to the slide plate and transmitting and receiving ultrasonic waves obliquely in opposite directions, and the angle beam probe on a horizontal center line of the two angle beam probes and One vertical probe fixed and disposed at a position 180 ° opposite to the probe, the worm wheel shaft, the slide plate, two oblique probes and one vertical probe. And a holder that rotates on the outer peripheral surface of the test material while holding.

The vertical probe has a frequency of 7 MHz, a transducer size of 20 mm, and an acoustic lens (sound speed 2500 m / s).
The radius of curvature of s) is 80 mm.

The oblique probe has a frequency of 5 MHz, a transducer size of 28 mm, and an acoustic lens (sound speed 2500 m /
The radius of curvature of s) is 47.5 mm.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a sectional view showing an automatic ultrasonic flaw detector according to Embodiment 1 of the present invention. In the figure, 1 to 10 are the same as the conventional device,
11 is a vertical probe according to the present invention, 12 is an oblique probe according to the present invention, 13 is a worm, 14 is a worm wheel shaft, 15 is a slide plate, 16a is a right-hand thread, 16b is a left-hand thread, and 17 is a left-hand thread. A first nut, 18 is a second nut, 19 is a probe holder, XX 'is a horizontal center line passing through the center of the test material 1, and YY' is a center line of the test material 1. A vertical center line, Y1 is the distance from the center of the test piece 1 to the surface of the vertical probe 11, Y2 is the distance from the center of the test piece 1 to the surface of the bevel probe 12, and X1 is the bevel probe. Child 12
Is the amount of eccentricity between the center of the sample and the center line YY ′ of the test sample 1.

In the automatic ultrasonic flaw detector configured as described above, the vertical probe 11 is connected to the vertical center line Y-
Since it is fixed on Y ′, even if the outer diameter of the test material 1 changes from φ18 to φ131, the ultrasonic wave can always be transmitted and received toward the center of the test material 1. On the other hand, in the oblique probe 12, even if the outer diameter of the test piece 1 changes from φ18 to φ131, the outer diameter It is necessary to change the amount of eccentricity X1 between the center of the oblique probe 12 and the vertical center line YY 'of the test material 1 according to the change.

Next, a method of changing the eccentric amount X1 of the oblique probe 12 will be described. When the worm 13 protruding outside the probe holder 9 is rotated, the rotational force is transmitted to the worm wheel shaft 14 and the worm wheel shaft 14 rotates. At this time, the worm wheel shaft 14
By attaching a right thread 16a to the right end and a left thread 16b to the left, the first nut 17 and the second nut 18 receiving the rotational force of the right thread 16a and the left thread 16b are attached. The vertical center line Y-
They make line-symmetrical movements toward and away from Y '. The first nut 17 and the second nut 17
The slide plate 15 is attached to the nut 18 of
Further, the slide plate 15 is provided on each of the oblique probes 1
2, the two oblique probes 12 can operate to change the eccentric amount X1 in accordance with the rotation of the worm 13, and the outer diameter of the specimen 1 is φ1.
Even if it changes from 8 to φ131, the incident angle of the ultrasonic wave transmitted / received from each of the oblique probes 12 to the surface of the test material 1 can be controlled to be constant only by automatically controlling the rotation speed of the worm 13.

The distance Y1 from the horizontal center line XX 'of the test sample 1 to the vertical probe 11 and the angle probe 12
Is constant regardless of the outer diameter size of the test material 1. Therefore, in a device in which the probe holder 19 rotates around the test material 1, a stable rotation balance of the holder 19 is always obtained. Will be.

Embodiment 2 FIG. 2 is a sectional view of a vertical probe according to a second embodiment of the present invention. Table 1 shows eccentricity between the center of the vertical probe and the center of the test material when the outer diameter of the test material 1 is 18 mm. Table 2 shows the sensitivity change amount of the center flaw due to the eccentricity between the center of the vertical probe and the center of the test material when the test piece 1 is 131 mm. . In the figure, reference numeral 20 denotes a vibrator for transmitting and receiving ultrasonic waves;
Is an acoustic lens made of resin, 22 is a damper, A is an opening size of the vibrator 20, R is a radius of curvature of the acoustic lens 21, ΔX
Is the amount of eccentricity between the vertical center line YY ′ of the test sample 1 and the center of the vertical probe 11.

[0017]

[Table 1]

[0018]

[Table 2]

In the vertical probe 11 configured as described above, the front side of the transducer 20 for transmitting and receiving ultrasonic waves facing the test material 1 is made of plastic such as epoxy resin for the purpose of converging the ultrasonic waves. A vibrator 20 including an acoustic lens 21
A damper 2 for suppressing free vibration of the vibrator 20 is provided on the rear side of the
2 are provided. In the apparatus according to the present invention, the test material 1
Since the distance Y1 between the horizontal center XX ′ and the vertical probe 11 is constant, the horizontal distance L1 is long when the outer diameter of the test piece 1 is φ18, and when the outer diameter is φ131, The horizontal distance L1 becomes shorter. Therefore, the points of the design of the vertical probe 11 are to make the ultrasonic waves as narrow as possible inside the φ1 test material 1 and to reduce the eccentricity between the φ131 test material 1 and the vertical probe 11. It is necessary to balance sensitivity stability. That is, when the surface shape of the test material 1 is cylindrical or columnar, the surface of the test material 1 becomes a diffusion type acoustic lens ultrasonically due to the difference in sound speed from the couplant 8, so that, for example, In order to obtain an S / N ratio of 26 dB or more for an artificial defect consisting of a 1 mm side hole, it is necessary to converge the ultrasonic beam. However, extreme convergence may result in a large change in sensitivity to eccentricity between the test sample 1 and the vertical probe 11, so that it is necessary to find optimal conditions. Φ1 at optimum condition setting
In the outer diameter of the test material 1 of 8, the effect of the diffusion of the ultrasonic wave on the surface of the test material 1 is greater than the convergence of the ultrasonic wave by the acoustic lens 21. And the radius of curvature R of the acoustic lens 21 are, for example, −3
There are a wide range of options under conditions where the amount of change in sensitivity is smaller than dB. On the other hand, the outer diameter of the test piece 1 having the diameter of φ131 is directly affected by the acoustic lens 21 provided on the vertical probe 11, so that
In order to prevent the defect detection sensitivity from changing significantly (−3 dB) even in the state of eccentricity (about 2 mm) allowed in the actual line of the steelworks, as shown in Table 2, the aperture size A of the vibrator 20 is required.
Is 17.5 mm, the radius of curvature R of the acoustic lens 21 is
Is 80 mm or the opening size A of the vibrator 20 is 20 mm.
mm, the radius of curvature R of the acoustic lens 21 is 70 mm
And 80 mm. That is, in Tables 1 and 2, the condition under which the change in sensitivity is the least due to the combination of the aperture size A of the vibrator 20 and the radius of curvature R of the acoustic lens 21 is that the aperture size A of the vibrator 21 is 20 mm and the radius of curvature of the acoustic lens 21 The vertical probe 11 has a radius of 80 mm.
The acoustic velocity of the acoustic lens is 2500 m / s. Further, it is better to select a high frequency in order to narrow the pulse width of the surface echo generated on the surface of the test material 1. However, if the frequency is too high, a forest-like echo due to irregular reflection from the tissue of the test material 1 will be generated. 7 MHz is optimal for the frequency to generate.

Embodiment 3 FIG. 3 is a sectional view for explaining a third embodiment according to the present invention, and FIG.
FIG. 3 is an S / N contour diagram showing the ratio of a side hole defect echo due to a transverse wave to a bottom surface echo due to a longitudinal wave as a relative change amount, with the horizontal axis representing the radius of curvature R of the acoustic lens and the vertical axis representing the aperture dimension A of the vibrator. . In the figure, 30 is a transverse wave generated in the test material 1, 31 is a longitudinal wave passing through the approximate center of the test material 1, A is frequency = 5 MHz, vibrator aperture size A = 15 mm, acoustic lens curvature radius R = The S / N characteristic point at 50 mm and b are the conditions (frequency = 5 MHz) of the oblique probe 12 according to the present invention.
z, the transducer aperture dimension A = 28 mm, the acoustic lens curvature radius R = 47.5 mm).

In the oblique probe 12 configured as described above, when the outer diameter of the test piece 1 is the smallest, the sub-beam of the ultrasonic beam propagates near the center of the test piece 1 as a longitudinal wave 31. The longitudinal wave 31 is received as S / N
The level must be reduced as much as possible because it is the main cause of characteristic noise. On the other hand, since the longitudinal wave 31 decreases to a negligible level as the outer diameter of the test material 1 increases, the outer diameter range of the test material 1 is from φ18 to φ13.
In order to obtain the oblique probe 12 corresponding to one type, the ratio of the flaw echo due to the transverse wave 30 to the bottom echo due to the longitudinal wave 31 at the minimum diameter φ18 is set to a predetermined value (for example, 26 dB).
Above).

The ratio between the transverse wave 30 echo from the transverse hole 10 having a diameter of 1 mm and the longitudinal wave 31 echo passing near the center of the test material 1 is S / N.
4 is shown as an S / N contour diagram in FIG. 4, where the point A is a frequency of 5 MHz, the aperture size A of the vibrator 20 is 15 mm, and the radius of curvature R of the acoustic lens 21 is 50 m.
S / N point of the oblique probe 12 under the condition of m (=
16 dB), and under the above conditions, the desired S / N (26 dB)
B or more), the aperture size A of the vibrator 20 and the acoustic lens 21
As a result of calculating a condition that the S / N ratio satisfies 26 dB or more using the radius of curvature R as a parameter, an S / N ratio of 9 dB to 12 dB with respect to the S / N point a with the region B in the drawing as a reference.
N improvement range, and the vibrator 2
When an oblique probe was manufactured with the opening dimension A of 0 being 28 mm and the radius of curvature R of the acoustic lens 21 being 47.5 mm, the S / N was measured and an S / N of 30 dB was obtained. According to FIG. 4, when the aperture dimension A of the vibrator 20 is 25.5 mm or more, the radius of curvature R of the acoustic lens 21 can satisfy the S / N ratio of 26 dB or more in a combination of about 45 mm to about 49 mm.
In order to reduce the size of the bevel probe 12 in consideration of the manufacturing error, it is preferable that the opening dimension A of the vibrator 20 is 28 mm and the radius of curvature R of the acoustic lens 21 is 47.5 mm. still,
The sound speed of the acoustic lens is 2500 m / s.
Further, it is better to select a high frequency in order to narrow the pulse width of the surface echo generated on the surface of the test material 1. However, if the frequency is too high, a forest-like echo due to irregular reflection from the tissue of the test material 1 will be generated. 5 MHz is optimal for the frequency to generate.

[0023]

Since the present invention is configured as described above, it has the following effects.

A worm, a worm wheel shaft, a right-hand thread and a left-hand thread are provided on the probe holder, a slide plate is provided on the right-hand thread and the left-hand thread via a nut, and an oblique angle is provided on the slide plate. Because the probe is fixed, even when the size of the test material changes, it is only necessary to rotate the worm and move the oblique probe in the horizontal direction. The probe holder, vertical probe, and beveled probe also have an outer diameter of 18 to 1
In the range of 31, only one type can be used, so that a low-cost device can be realized.

The frequency of the vertical probe is 7 MHz, the aperture size of the vibrator is 20 mm, and the radius of curvature of the acoustic lens is 8
0 mm (when the sound speed of the lens is 2500 m / s)
The outer diameter range φ of the test material with one type of probe
A stable high S / N ratio can be provided from 18 to φ131.

The frequency of the oblique probe is 5 MHz, the opening size of the vibrator is 28 mm, and the radius of curvature of the acoustic lens is 4 mm.
Since it is 7.5 mm (when the sound speed of the lens is 2500 m / s), one type of probe can provide a stable high S / N ratio in the outer diameter range of φ18 to φ131 of the test material. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an automatic ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a vertical probe according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an oblique probe according to Embodiment 3 of the present invention.

FIG. 4 shows the S / S of the bevel probe according to the third embodiment of the present invention.
It is an N contour map.

FIG. 5 is a cross-sectional view showing a conventional automatic ultrasonic flaw detector.

[Explanation of symbols]

1 test material, 11 vertical probe, 12 bevel probe, 1
3 worm, 14 worm wheel shaft, 15 slide plate, 1
6a right screw part, 16b left screw part, 17 first net, 18 second nut,
19 probe holder, 20 transducer, 21 acoustic lens, 22 damper, 30 transverse wave, 31 longitudinal wave, b S / N area of oblique angle probe.

Claims (3)

[Claims] 1. A vertical probe for transmitting and receiving ultrasonic waves perpendicularly to a center of a cylindrical test material, and first and second ultrasonic sensors for transmitting and receiving ultrasonic waves to and from the test material obliquely in opposite directions to each other. In an automatic ultrasonic flaw detector which includes a bevel probe and inspects a flaw present inside a test material, the vertical distance between the first and second bevel probes from the center of the test material is determined. A right-hand thread part and a left-hand thread part are provided at each end for moving the center positions of the first and second bevel probes in a direction opposite to each other in a horizontal direction with respect to the center of the test material while keeping the center constant. A worm wheel shaft, a first nut coupled to the right threaded portion of the worm wheel shaft, a second nut coupled to the left threaded portion, and coupled to the first and second nuts, respectively. Slide plate and the slide plate fixed to the slide plate and tilted in opposite directions. First and second bevel probes for transmitting and receiving ultrasonic waves, and on the center line of the first and second bevel probes in the horizontal direction, and with respect to the bevel probe A vertical probe fixedly disposed at a position facing 180 °;
A holder for holding the worm wheel shaft, the slide plate, the first and second angled probes, and the vertical probe, the holder being configured to rotate on the outer peripheral surface of the test material. Automatic sound wave flaw detector. 2. The vertical probe has a specimen diameter of 18 mm.
The frequency is 7 MHz, the vibrator size is 20 mm, and the acoustic lens (sound speed is 2500 m / s) so that a predetermined S / N (S / N ≧ 26 dB in the φ1 side hole) can be secured under one kind of condition in a range of from 131 mm to 131 mm. 2. The automatic ultrasonic flaw detector according to claim 1, wherein the radius of curvature is 80 mm. 3. The bevel probe has a specimen diameter of 18 mm.
The frequency is 5 MHz, the vibrator size is 28 mm, and the acoustic lens (sound speed is 2500 m / s) so that a predetermined S / N (S / N ≧ 26 dB in the φ1 side hole) can be ensured under one type in a range of from 131 mm to 131 mm. 47.5mm radius of curvature
2. The automatic ultrasonic flaw detector according to claim 1, wherein: