JPH03257362A - Ultrasonic flaw detection apparatus - Google Patents

Abstract

PURPOSE:To detect a flaw with high reliability by reducing a flaw undetected region by calculating the distance up to the corner part of an oblique angle probe by utilizing the beam distance up to the bottom surface of a material to be inspected due to the ultrasonic beam of an oblique probe. CONSTITUTION:A beam distance operation circuit 11 uses the distance X up to the bottom surface of a material 1 to be inspected measured by the vertical probe 2a present at the almost same position as an oblique angle probe 2n and the distance S from the probes 2a, 2n to the side surface of the material 1 to be inspected is used to calculate the distance Y up to the corner part to which the beam from the oblique angle probe 2n goes. When the position of a bottom surface echo B moves to a position B' by some cause, since a flaw detection gate FG changes like FG' according to the moving quantity, the position of the flaw detection gate FG is controlled according to the fluctuation of the distance Y up to the corner part so as to follow a member 9 to prevent the generation of a flaw undetected region or the erroneous detection of the bottom surface echo.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an ultrasonic flaw detection device that uses ultrasonic waves to inspect the presence or absence of defects inside square billet steel materials transported in a steel production line. It is something.

[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 the inspected material. 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, Japanese Unexamined Patent Publication No. 58-61462 discloses an ultrasonic flaw detection method and apparatus for billets using a plurality of flaw detection contacts.

FIG. 4 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 the square billet (cross-sectional view) that is the material to be inspected, f2a)-(2dl is a group of ultrasonic probes arranged on one side of the square billet, (3al-(3dl is each ( 2a) - The transducer housed in each probe of (2d), (4a) - (4dl are each (3a)
-(This shows the beam spread (flaw detection range) within the rectangular billet (1) of the ultrasonic waves generated by each 3dl transducer.

Also, (5a)-(5dl, (6a)-(6
dl , (7a) - (7dl all represent probe groups placed on different faces of the square billet, and each of them has an ultrasonic beam similar to (4al - (4d)) (omitted in the figure) 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 5 shows an example of a flaw detection mechanism in a square billet conveyance line, with Figure 5 (a) being a front view and Figure 5 (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), flaw detection is carried out while repeating the operation of the probe holder making contact with the material at the tip and separating the material at the rear end.

In conventional automatic ultrasonic flaw detection equipment, one individual ultrasonic probe is arranged 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. 4. 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 1. is necessary. In addition, since vertical probes leave some undetected areas in corners of square billets, many devices are now equipped with angle probes for partially detecting corners. It's here.

Method 1: In normal ultrasonic automatic flaw detection equipment.

The bottom echo is used so that the position of the defect detection gate changes to keep the undetected area as small as possible as the thickness of the couplant (water gap) and the dimensions of the inspected material change. It usually has a tracking function for the defect detection gate position.

[Problems to be Solved by the Invention] In conventional automatic ultrasonic flaw detection equipment, in order to prevent the occurrence of undetected areas inside the square billet as much as possible, the ultrasonic beams generated by the vertical probes must be The interior will be inspected by expanding over a certain width, and the remaining corners will be covered with an angle probe. moreover,
It is necessary for the defect detection gate to always track the position of the bottom echo so that it reaches the very edge of the bottom surface.

On the other hand, in the case of an angle probe, the level of the bottom echo is so low that a satisfactory bottom position cannot be obtained, so the tracking function of the defect detection gate tends to become unstable. The problem to be solved by this invention is to stably perform the tracking function of the defect detection gate position in order to minimize the undetected area even in an angle probe.

[Means for Solving the Problems] In order to determine the distance from the position of the angle probe to a part of the corner toward which the beam is directed, the ultrasonic flaw detection device according to the present invention is arranged at approximately the same position. The thickness of the square billet was measured with a vertical transducer.

The known distance from the probe position to the side surface is used for calculations, and the position of the defect detection gate of the angle probe is tracked using the results.

In addition, in the case where the distance to the side surface toward which the beam of the above-mentioned angle probe is directed changes depending on the dimensions of the square billet, the present invention can be installed on the same probe tracking mechanism and separate from the above-mentioned side surface. First measure the thickness of the orthogonal billet with a vertical probe attached to the opposite surface, then subtract a constant value from that value to determine the distance to the side where the beam of the angle probe is facing. By knowing this, the position of the defect detection target 1- is tracked while performing the same calculation, and the occurrence of undetected areas is minimized.

[Operation] In this invention, the thickness of the square billet is measured with a vertical probe located at approximately the same position as the angle probe, and calculations are performed using that value and the distance from the probe to the side surface of the square billet. By doing this, find the distance from the angle probe to the part of the corner where the beam is heading.

By tracking and changing the position of the defect detection gate according to the distance, the occurrence of undetected areas in the bevel probe is reduced.

[Example 1] Figure 2 shows an example according to the present invention, in which (1) is the material to be inspected, (2n) is the ultrasonic vertical probe, and (2a) is the ultrasonic vertical probe. Ultrasonic angle probe, and an angle probe, (9) is a tracking mechanism that holds the above probe and places it on the surface of the square billet, (10) is a transmitting/receiving circuit connected to the electrode of each probe, (ill is A beam path calculation circuit that receives the received signal from the transmitter/receiver circuit and calculates the distance to the corner of the angle probe from the thickness of the square billet measured with the vertical probe and the distance to the side surface of the square billet of the probe. It is.

Further, L is a coaxial cable connecting the probe and the transmitting/receiving circuit, and R is a received signal.

Now, in the ultrasonic flaw detection device configured as above, the ultrasonic beam X emitted by the vertical probe (2n) hits the bottom of the square billet perpendicularly, so a stable reflected echo can be obtained. Since the probe beam y emitted by the probe (2a) is directed towards a part of the corner of the square billet, a stable bottom echo cannot be obtained. As a result, gate tracking, which causes the position of the defect detection gate to follow changes in the position of the bottom echo, becomes impossible, and the end position of the defect detection gate has a certain margin so that the bottom echo will not be detected at any time. It will be fixed and set in front of the bottom echo at a certain distance. Therefore, it is unavoidable that the undetected area near the bottom surface increases by the margin distance.

The ultrasonic flaw detection device according to the present invention shown in FIG. 1 has been developed to compensate for the above-mentioned drawbacks. Now, the distance S from the position of the angle probe (2a) to the end face of the square billet
As is clear from FIG. 1, when y is known, the beam path distance y to the bottom of the angle probe is expressed as follows.

y=f7177 (1) From the above equation, y can be calculated by knowing the beam path length X to the bottom of the vertical probe (2n).

FIG. 2 shows another embodiment of the ultrasonic flaw detection apparatus according to the present invention, in which the same parts as in FIG. 1 are marked with the same markings. Now, in Figure 2, the position of the angle probe is determined by the tracking mechanism (
9), and the distance S between the position of the bevel probe and the end face of the square billet changes depending on the dimensions of the square billet and does not take a constant value. In this case, taking advantage of the fact that the distance to the opposite end face is constant regardless of the size of the square billet, the probe is first housed in the same probe tracking mechanism.
Determine the beam path length 2 to the bottom of the vertical probe (5n) located on a different plane at a 90° angle. the result.

The distance tiiis to the end face of the angle probe (2a) is expressed by the following formula.

5=z−t... (2) Substituting the above equation (2) into equation (1), the angle probe (2a)
The beam path length y to a part of the corner of is determined by the following formula.

Y-! P=]7: 汀r...(3) As described above, the beam path calculation circuit (11) that receives the reception signal R via the transmitter/receiver circuit (lO) calculates the beam path to the bottom of the vertical probe. By finding , the distance from the angle probe position to the part of the corner where the beam is heading can be calculated using the fi1 formula in Figure 1 and the formula (3) in Figure 2. can.

FIG. 3 shows an example of the tracking operation of the end position of a defect detection gate using a general bottom echo, where SG is a surface echo detection gate and FG is a defect detection gate. Now, the position of bottom echo B is changed to B due to some reason.
When moving to the position ', the defect detection gate also changes from FG (solid line) to FG' (broken line) according to the amount of movement, in order to prevent undetected areas and false detection of bottom echoes as much as possible. controlled. In this invention, the position of the defect detection gate is made to follow the variation of the beam path length y to the corner of the angle probe which is the output of the beam path calculation circuit (11).

[Effects of the Invention] As described above, according to the present invention, the distance to a part of the corner of the angle probe can be calculated by using the beam path to the bottom surface of the ultrahigh wave beam of the vertical probe. By,
It is possible to stably track the position of the defect detection gate, and it is possible to provide a highly reliable device with a small number of undetected areas.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the ultrasonic flaw detection device according to the present invention, FIG. 2 is a diagram showing another embodiment of the ultrasonic flaw detection device according to the present invention, and FIG. 3 is a diagram showing the defect game tracking operation. FIG. 4 is a diagram showing an example of the conventional technique, and FIG. FIG. 3 is a diagram showing an example of a flaw detection mechanism in a square billet conveyance line. In the figure, (1) is the material to be inspected, (2) is the ultrasonic probe, (3) is the transducer, and (4) is the ultrasonic beam (5). (7) is an ultrasonic probe, (8) is a probe holder, (9) is a tracking mechanism, (101 is a transmitting/receiving circuit, and (11) is a beam path calculation circuit. Note that the same symbols in Figure 9 are the same. or a considerable portion thereof.

Claims (2)

[Claims] (1) A vertical probe that injects ultrasonic waves perpendicularly to the surface of the square billet, an oblique probe that injects ultrasonic waves obliquely to the surface, and a probe that is connected to each of the above probes. In an ultrasonic flaw detection device consisting of multiple transmitter/receiver circuits, the thickness of the square billet measured with a vertical probe placed at approximately the same position as the above-mentioned angle probe with respect to the cross section of the square billet, and the thickness of the square billet Equipped with a beam path calculation circuit that calculates the distance from the position of the angle probe to the side of the corner billet to which the beam is directed, to the corner of the billet to which the beam of the angle probe is directed. and the position of the defect detection gate of the bevel probe is tracked based on the distance from the bevel probe to the corner determined by the beam path calculation circuit. Sonic flaw detection equipment. (2) The distance from the position of the angle probe to the side surface toward which the beam of the angle probe is directed varies depending on the dimensions of the square billet, and the distance from the side surface to the side surface facing the beam of the angle probe varies depending on the dimensions of the square billet. If the distance to the side surface of The distance from the position of the angle probe to the side surface toward which the beam is directed is obtained by subtracting the constant distance from the thickness. The ultrasonic flaw detection device described in (1).