JPH03257363A - Ultrasonic flaw detection apparatus - Google Patents

Abstract

PURPOSE:To detect various disorders and to enhance the reliability of each function by converging the ultrasonic beams of a plurality of vibrators to enhance sensitivity and using a reduced number of the vibrators less than the number of ones used at the time of flaw detection to perform the transmission and reception of an ultrasonic wave. CONSTITUTION:At the time of flaw detection, when vibrators 3a - 3c are selected by a transmission and reception selecting circuit 11 to be simultaneously driven, this state becomes same to such a state that a vibrator having an area three times equiva lently is driven and a narrow beam ultrasonic wave 4A is generated. When adjacent vibrators are selected like 3b - 3d' 3c - 3e by the circuit 11 and successively shifted at every definite time interval, the flaw detection of a material 1 to be inspected can be uniformly performed with high sensitivity by narrow beam ultrasonic waves 4A - 4D generated from respective vibrator groups. Next, when a reduced number of vibrators less than the number of ones used at the time of flaw detection, for example, only the vibrators 3b' 3e are driven at a time separate from flaw detection, ultrasonic beams 4b' 4e become wide in beam directional angle and, therefore, a stable surface reflected echo or bottom surface reflected echo is obtained. Therefore, the check of an acoustic coupling state or the tracking of a flaw detection gate position becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic flaw detection device that uses ultrasonic waves to inspect the presence or absence of defects inside steel materials in a steel production line.

[Prior art] In the ultrasonic flaw detection method, an ultrasonic sensor generally called a probe emits ultrasonic waves, and the ultrasonic waves are transmitted through an acoustic propagation medium (called a couplant) such as water to a material to be inspected. The presence or absence of defects is detected by receiving reflected echoes from defects in the material to be inspected, and various devices are used depending on the shape and size of the material to be inspected9. For example, JP-A-58-61462 discloses an ultrasonic flaw detection method and apparatus for billets using a plurality of probes.

FIG. 5 shows, as an example of the prior art, the arrangement of ultrasonic probes of an automatic ultrasonic flaw detection device for square billets and the concept of ultrasonic beams in the cross section of square billets.

In the figure, (1) is a square billet (cross-sectional view) that is the material to be inspected, and (2a) to (2d) are a group of ultrasonic probes arranged on one side of the square billet. ) are the transducers housed in each of the probes (2a) to (2d), and (4a) to (4dl are (3a), respectively)
~(3dl) Each transducer indicates the beam spread (flaw detection range) within the square billet (1) of the ultrasonic waves generated by each vibrator. Also, (5a) ~(5dl)
, (6a) ~(6dl.

(7a) to (7d) are all arranged on different sides of the square billet and represent probe groups, and (4a) to (7d) are respectively arranged on different sides of the square billet.
An ultrasonic beam (omitted in the figure) similar to (4d) is generated. In the automatic ultrasonic flaw detection device for square billets, flaw detection is performed over the entire length from the leading edge to the trailing edge by transporting the square billet in a direction perpendicular to the plane of the drawing.

Figure 6 shows an example of a flaw detection mechanism in a square billet conveyance line, with Figure 6 (a) being a front view and Figure 6 (b) being a front view.
) is a side view. In fig.

The ultrasonic probe is stored in an upper probe holder (8a) and a lower probe holder (8b), and when a square billet, which is the material to be inspected, is conveyed, the upper tracking mechanism (9a) and the lower tracking mechanism By activating (9b),
The probe holder (8al (8bl) contacts the material at the tip and releases the material at the rear end, which is repeated for flaw detection.

In conventional automatic ultrasonic flaw detection equipment, two individual ultrasonic probes are placed side by side on each side of a square billet in order to inspect the presence or absence of internal defects in the square billet, as shown in Fig. 5. The number of probes that can be lined up is naturally limited by the planar dimensions of the billet and the width of the probes, and the number of probes per surface is usually about four. In that case, in order to prevent the occurrence of undetected areas inside the square billet as much as possible, the ultrasonic beam of each probe must spread out over a certain width, as is clear from Figure 2. is necessary.

Method 7: In normal ultrasonic automatic flaw detection equipment.

In order to check whether the ultrasonic beam emitted from the ultrasonic probe is properly entering the material to be inspected via the couplant, the ultrasonic waves reflected from the surface or bottom of the material to be inspected are used. Judgment is made based on the echo height level of the echo. Equipped with a function to check the operation of the device and the state of acoustic coupling.

A surface echo or a bottom echo is often used as the target echo. In addition, as the thickness of the couplant (water gap) and the dimensions of the inspected material change, the position of the defect detection gate changes accordingly so that the undetected area becomes as small as possible. It usually has a tracking function for the defect detection gate position using backplane echo.

In conventional automatic ultrasonic flaw detection equipment, the ultrasonic beams generated by the ultrasonic probe are each spread out over a certain width in order to minimize the occurrence of undetected areas inside the steel material. It is necessary to be present. However, this results in a decrease in sensitivity, and the problem is that the degree of decrease increases as the distance from the probe increases, especially when inspecting materials that have high attenuation of ultrasonic waves. , Small defects could not be detected because the S-/N (signal-to-noise ratio) could not be ensured. In order to deal with such problems,9 for example, as disclosed in Japanese Patent Publication No. 63-44195 (Linear electronic scanning method for ultrasonic probe), a plurality of transducers arranged in a plane are arranged adjacent to each other. By electronically scanning and transmitting and receiving ultrasound while sequentially shifting N transducers as a unit, the beam is focused equivalently to the S/
Methods to suppress N have also been adopted.

[Problem to be solved by the invention] In conventional ultrasonic flaw detection equipment, in order to improve sensitivity and S/N, multiple transducers arranged in a plane are simultaneously driven, thereby preventing the ultrasonic beam from spreading. If the directivity angle is made small, the level of the single surface echo and bottom echo tends to fluctuate and become unstable due to the effects of irregularities on the surface of the steel material and variations in the gap between the ultrasonic probe and the material to be inspected. The problem to be solved by this invention is to stably perform the function of checking the operation of the device, checking the acoustic coupling state, and tracking the position of the defect detection gate while improving the flaw detection sensitivity.

[Means for Solving the Problems] The ultrasonic flaw detection device according to the present invention has a plurality of transducers and corresponding electrodes arranged and built into one ultrasonic probe, and some of them have predetermined By simultaneously applying voltage to a set number of adjacent electrodes, the ultrasonic beam is narrowed down by operating it as one equivalently large transducer, improving sensitivity and S/N. Ultrasonic waves are transmitted and received at a different time from the time of flaw detection using fewer or one suitable transducer than during flaw detection to obtain more stable surface echoes and bottom echoes, which can be used to check the operation of the equipment and The bonding state is checked and the defect detection gate position is tracked.

[Operations] In this invention, in an ultrasonic flaw detection device that simultaneously applies a voltage to a plurality of adjacent electrodes to operate as an equivalently large vibrator, the ultrasonic beam is narrowed and the sensitivity is improved. When checking the operation of the equipment, checking the acoustic coupling state, and racking to defect detection gate position 1 using bottom echo or surface echo, it is necessary to use a smaller number of appropriate sensors at a different time than during flaw detection. By using a transducer to transmit and receive ultrasonic waves, fluctuations in the echo level are suppressed as much as possible.

This allows for more stable operation.

[Example] Fig. 1 shows an example according to the present invention, in which (1) is a material to be inspected, (2) is an ultrasonic probe, and (3al to (3f) are The transducers housed in the ultrasonic probe (2), (4A) to (4D) are the ultrasonic beams generated by each transducer group, and (10a) to (lof) are the transducers (3a) to (4D), respectively. The transmitter/receiver circuit connected to the electrode (3f), (Ill) simultaneously drives the transmission of any plurality of circuits in the transmitter/receiver circuit (10) at an arbitrary timing, and also receives reception from the driven vibrator. This is a transmission/reception selection circuit that combines and extracts only signals.

Further, L indicates a coaxial cable connecting the probe and the transmitter/receiver circuit, T indicates a transmission command signal, and R indicates a reception signal.

Now, in the ultrasonic flaw detection apparatus configured as described above, at time 2 t1, the transmitter/receiver selection circuit fill is switched to the transmitter/receiver circuit (l
oa) to (tOC), and select transducers (3a) to (3c
) and receiving the reflected ultrasound at the same time, it is equivalent to driving a transducer with three times the area, and a narrow beam ultrasound (4A) is generated.
By generating this, it becomes possible to perform flaw detection with higher sensitivity than when only -1 transducers are driven.

Next, at time t2, the vibrator (3b) ~
Ultrasonic beam (4B) is generated by simultaneously driving (3d).
occurs, and in the same way, at time t3, the oscillator (3c) ~
(3e) and the ultrasonic beam (4G) is transmitted at time t4.
The ultrasonic beam (
4D) occurs. In this way, by sequentially shifting certain adjacent transducers at regular time intervals, the ultrasonic waves generated from the transducer group move one after another while maintaining a narrow beam, and the inspected material +11 can be inspected with high sensitivity. It becomes possible to perform flaw detection without bias.

In Fig. 1, there are three vibrators driven simultaneously.
Although the ultrasonic beam is shown for the case of 4 or 5 ultrasonic beams, it is clear that the same effect can be obtained even if the number is different, such as 4 or 5.

On the other hand, in the ultrasonic flaw detection device configured as described above, the directivity angle of the ultrasonic waves is small and the beam is sharp, so the defect detection ability is high. It is susceptible to changes in the gap between the inspected material and the ultrasonic probe, and tends to become unstable. - Numerically speaking, automatic ultrasonic flaw detection equipment monitors the height of reflected echoes from the surface and bottom surface in order to check whether the ultrasonic beam emitted from the transducer is reliably transmitted to the inspected material. There is a function to check the acoustic coupling state to confirm that it is normal, and to minimize the undetected area, the position and range of the defect detection gate is moved as close as possible to the surface and bottom while monitoring the position of reflected echoes on the surface and bottom. It is common to have a gate tracking function.

Therefore, in this invention, an ultrasonic beam with a wide directivity angle is generated by applying voltage to a smaller number of suitable transducers than during flaw detection at a time different from the flaw detection time, and stable surface reflection echoes are generated. This system is designed to check the acoustic coupling state and track the position of the defect detection gate by obtaining the bottom surface reflection echo.

FIG. 2 shows an example of the state of the ultrasonic beam at that time, and the configuration is the same as that in FIG. 1.

In the figure, (4b) is the ultrasonic beam when only the transducer (3b) is driven, and (4e) is the ultrasonic beam when the transducer (3b) is driven.
It shows the ultrasonic beam when only 3e) is driven. As shown in the figure, the directivity angle of the ultrasonic beam is wider than in the case of FIG. 1, and stable echoes reflected from the surface and reflected echoes from the bottom surface can be obtained. Furthermore, it goes without saying that similar effects are obtained when other vibrators are driven.

FIG. 3 shows, in chronological order, the operation of transmitting and receiving echoes of the ultrasonic flaw detection apparatus of FIGS. 1 and 2 according to the present invention. In the figure, TI-T5 is the transmitted echo of the ultrasonic probe, and Sl-S5 is the surface echo reflected from the boundary between the ultrasonic probe and the material to be inspected.B1-85 is the echo reflected from the bottom surface of the material to be inspected. On the bottom surface (11) (12) is Co. Here, time tl, t2. t3. At t4, as shown in FIG. 1, each of the three vibrator groups is sequentially driven while shifting, and each (4Al).

Flaw detection is performed using the ultrasonic beams (4Bl, (4C), and (4D).Next, at time t5 of 9, one transducer (second
In the figure, (3b) or (3el) is driven independently, and the ultrasonic beam at that time ((4b) or (4e) in Figure 2 is
)) The acoustic coupling state is checked and the defect detection gate position is tracked by stable surface echoes and bottom echoes.

FIG. 4 shows an example of the tracking operation of the end position of the defect detection gate using the bottom echo at that time, where SG is the surface echo detection gate and FG is the defect detection gate. If the position of the bottom echo B5 moves to the B5' position due to some reason, the defect detection gate will change from FG (solid line) to FG' (dashed line) according to the amount of movement, causing the occurrence of undetected areas and Control is performed to prevent false detection of bottom echoes as much as possible.

On the other hand, when multiple transducers are driven at the same time as in the ultrasonic flaw detection device according to the present invention, even if one of the transducers is malfunctioning due to some reason such as a cable break, it is not a phenomenon. In many cases, the sensitivity is only slightly reduced and is not noticed. Therefore, it is important to check for such defects in advance and notify the operator.In this invention, a voltage is applied to each vibrator individually at an appropriate time other than the time of flaw detection, and the By checking the sensitivity using surface echoes, it is possible to detect defects such as wire breaks.

[Effects of the Invention] As described above, according to the present invention, a focused ultrasonic beam can be incident on a steel material while sequentially shifting its position.
It will be possible to inspect steel materials with high performance.

Further, in the explanation so far, only the case where a vertical probe is used has been described, but the same effect can be obtained with an oblique probe that makes the ultrasonic wave obliquely enter the steel material.

Furthermore, by driving - or a smaller number of transducers than during flaw detection at a different time from flaw detection, stable surface echoes and bottom echoes can be collected, making it possible to check the acoustic coupling state using these echoes. This has the effect of improving the reliability of various functions such as tracking of defect detection gate positions and monitoring of equipment malfunctions.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an embodiment according to the present invention and an ultrasonic beam during flaw detection, and Fig. 2 is a diagram showing the configuration of an embodiment according to the present invention and the ultrasonic beam during flaw detection. FIG. 3 is a diagram for explaining an ultrasonic beam during tracking. FIG. 3 is a diagram showing in chronological order the operation of transmitting and receiving echoes of the ultrasonic flaw detector shown in FIGS. 1 and 2 according to the present invention, and FIG.
Figure 5 shows an example of defective gate tracking operation.
The figure shows the arrangement of ultrasonic probes and the ultrasonic beam in cross section in an automatic ultrasonic flaw detection system for square billets as an example of conventional technology, and Figure 6 shows an example of a flaw detection mechanism in a conveyance line for square billets. It is. In the figure, (1) is the material to be inspected, (2) is the ultrasonic probe, (3) is the transducer, (4) is the ultrasonic beam, and (5) to (
7) is an ultrasonic probe, (8) is a probe holder (9) is a tracking mechanism, (101 is a transmission/reception circuit, and fil) is a transmission/reception selection circuit. Note that the same reference numerals in FIG. 1 indicate the same or corresponding parts.

Claims (3)

[Claims] (1) An ultrasonic probe that includes a plurality of transducers and a plurality of electrodes corresponding to each transducer, a plurality of transmitting/receiving circuits connected to each of the electrodes, and an inside of the transmitting/receiving circuit. The transducer is equipped with a transmission/reception selection circuit for simultaneously operating the transmitting parts of any plurality of circuits at any timing to drive the vibrator, and for synthesizing and extracting only the received signals from the driven vibrators. , by simultaneously applying voltage to a plurality of electrodes adjacent to each other in a predetermined part of the ultrasound probe, the ultrasound beams generated from the plurality of transducers are equivalently focused; In an ultrasonic flaw detection device that inspects steel materials by injecting an ultrasonic beam into the steel material, a smaller number of mutually adjacent transducers or one sheet is detected at a time different from the time of flaw detection. An ultrasonic flaw detection device characterized in that the acoustic coupling state between an ultrasonic probe and a steel material is checked by driving a transducer and using echoes reflected from the surface or bottom of the steel material at that time. (2) A means for detecting the echo generation position of the reflected echo from the surface or bottom of the steel material when a smaller number of adjacent vibrators or a single vibrator than in the flaw detection described above is driven; 2. The ultrasonic flaw detection apparatus according to claim 1, wherein the position of the defect detection gate set in the steel material is controlled to follow the position of the defect detection gate set in the steel material. (3) At a time different from the above-mentioned flaw detection time, only one transducer is driven, and the operation of each transducer and the transducer are measured using the reflected echo from the surface of the ultrasonic probe at that time. 2. The ultrasonic flaw detection device according to claim 1, wherein the ultrasonic flaw detection device checks the operation of a circuit connected to the ultrasonic flaw detection device.