JPS6033048A - Scanning system for probe for flaw detection of hoop plate material - Google Patents

Abstract

PURPOSE:To reduce the acceleration applied to a mechanism part and eliminate play due to the acceleration, and perform flaw detection stably by putting plural probes and their holding member in circular motion and a material to be inspected in relative linear motion, and making a scan by their composite motion. CONSTITUTION:When a flaw of a hoop plate material is detected with an ultrasonic wave, the material 1 to be inspected is dipped in water while piercing a water tank 3, and when a rotating shaft 11 is rotated, a rotary ring 9 rotates to put respective probes 4a, 4d- mounted on the ring 9 in constant-speed circular motion. Simultaneously, when the material 1 to be inspected is moved continuously at a constant speed as shown by an arrow, the probes 4a, 4b- scan drawing cycloidal curves, which are as many as the proves and at equal pitch over the entire surface of the material 1 to be inspected. Consequently, a constant-speed scanning for flaw detection on the entire surface of the material 11 to be inspected is made without any discrimination between the center part and edge parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Applicability] The present invention relates to a probe scanning method in an apparatus for automatic ultrasonic flaw detection on the entire surface of a strip-shaped material such as a thin steel plate.

[Prior art]

When performing ultrasonic flaw detection on strip material, the method of flaw detection differs depending on the thickness of the material being tested. If it is relatively thick, for example 4 ten
If it is more than 4 tan, it is often detected by the one-probe reflection method, while if it is thin, for example, if it is less than 4 tan, it is often detected by the one-probe reflection transmission method. However, both flaw detection methods use the same probe scanning method. Therefore, in this specification, a case where flaw detection is performed by the -detection reflection transmission method will be explained as an example.

First, the -reflection transmission method will be explained with reference to FIGS. 1 and 2.

FIG. 1 is an explanatory diagram showing the principle of the one-probe reflection-transmission method. In the figure, a plate-shaped specimen 1 is immersed together with a reflecting plate 2 in a water tank 3. Although water is used here as the ultrasound medium, other liquids that propagate ultrasound can also be used.

The test material 1 and the reflecting plate 2 are held in a water tank 3 in a substantially parallel manner. Then, the probe 4 faces the test material 1 in the water tank 3.
immersed vertically.

When the ultrasonic pulse T is emitted from the probe 4 in this state,
Liquid surface reflection S01 of test material 1, delayed echo SOI due to repeated reflection between the front and back surfaces inside test material 1, surface reflection of reflector 2 81% again delayed due to repeated reflection between front and back surfaces inside test material 1 Reflected waves such as an echo f3o1 at each interface between the test material 1 and the reflection plate 2 are generated.

The A-scope waveforms of these reflected waves are shown in FIG. Here, if there is a defect in the ultrasonic flaw detection sound field of the test material 1, the ultrasonic propagation is blocked by this defect, and as a result, the echo level of the surface reflection S1 from the reflector plate 2 is reduced. -Using this, the probe reflection transmission method uses the gate F as shown in Figure 2.
The configuration is such that a defect detection signal is transmitted when the level of the S1 echo extracted at step C falls below a preset level L.

The above-mentioned cutting is the principle for flaw detection in the negative dimension, but when detecting flaws on the entire surface of a strip-shaped test material, it is necessary to scan the probe in the width direction of the plate.

Conventionally, there are two types of probe scanning methods of this type, such as those shown in FIGS. 3 and 4.

In these figures, the test material 1 penetrates the water tank 3,
Continuously transported in the direction of the arrow at a constant speed. The part of the water tank 3 that penetrates the test material 1 is
Rubber plates 3a, 3a' and 3 are provided on both the inlet and outlet sides.
b, 3b' K is performing water sealing. Also,
The water tank 3 includes a water supply pipe (not shown) for replenishing water and an overflow pipe 5 for maintaining the water level in order to prevent a drop in water level due to water leakage or the like. Multiple probes 4
m, 4b, . . . 4n are attached to the probe holding plate 6 in a row at equal intervals one by one in the width direction of the test material 1. This probe holding plate 6 has slide guides 7 on both ends thereof.
It is held slidably in the board width direction at a and 7b, and one end is connected to a reciprocating swing mechanism 8 that swings back and forth in the board width direction.

With the device configured in this manner, the probe holding plate 6 is oscillated in a forward and backward motion equal to the arrangement spacing of the probes 4a, 4b, . . . , 4n. , . . 4n scanning trajectories, for example, a plurality of sine wave trajectories as shown in FIG. 5 are obtained. Conventionally, flaw detection was performed using such a sine wave locus.

However, in such a conventional probe scanning method,
I have input like this: That is, normally, the purpose of detecting defects inherent in a strip is to detect defects that extend in the longitudinal direction of the strip during the rolling process, so as shown in FIG.
Compared to the minimum length of the defect to be detected, the wavelength of the probe scanning sinusoidal trajectory must be approximately equal to or shorter than this. For this reason, for example, the conveyance speed of the material to be inspected is set to 40
m/min, and the minimum length of the defect to be detected is 50 mm.
The probes 4m, 4b+...4n must be vibrated at 14 Hz with a full amplitude commensurate with the probe spacing. As a result, if the probe arrangement spacing is 5011II+1, an acceleration of about 10 G at maximum is always applied to each swinging mechanism. Therefore, there is a drawback that the mechanism part tends to become loose, and the mechanism and operation become unstable during flaw detection. In addition, since the medium in the water tank is vigorously stirred and shaken, air bubbles are drawn in, which disturbs the ultrasonic sound field and tends to make flaw detection impossible. .

Furthermore, in the conventional sine wave reciprocating scanning described above, as shown in FIG. Depending on the length of the scanning line, the length of the line intersecting the scanning line differs, which has the disadvantage that the flaw detection density is not uniform.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to reduce the acceleration applied to the mechanism by scanning a plurality of probes by combining circular motion and relative linear motion. This method eliminates rattling due to mechanical and operational stability, and does not stir or shake the medium in the water tank, thus eliminating air bubbles that disturb the ultrasonic sound field. It is possible to stably detect flaws without any
It is an object of the present invention to provide a probe scanning method for flaw detection of a strip material, which can evenly scan and detect the entire surface of a material to be inspected by keeping the pitch of the scanning locus constant.

[Structure of the invention]

The present invention involves ultrasonic flaw detection in which a part or all of a material to be inspected made of a strip-shaped material is immersed and held in a medium that propagates ultrasonic waves, and a probe is scanned over the entire surface of the material to be inspected. In a probe scanning method in a sonic flaw detection device, g) a means for arranging a plurality of probes at equal pitches on the same circumference and holding them on a surface parallel to the test material in the medium; (b) rotating means for circularly moving each of the probes along the circle/periphery; and (c) linearly moving the test material and means for holding the probe relative to each other. The present invention is characterized in that it is configured to include a means for drawing a group of scanning trajectories at an equal pitch over the entire surface of a material to be inspected.

According to such a configuration, each of the plurality of probes moves circularly on the same circumference and also moves relatively linearly in parallel with the test material, so that as a result of these movements, the surface of the test material is Draw a group of cycloid curve trajectories above. Each curve may have the same pitch no matter where it is located, but this pitch can be set as appropriate depending on the number of probes, the number of rotations of circular motion, the speed of relative motion, etc. It is possible to detect flaws with uniform and high density.

Further, 1. Since each probe only moves circularly at a constant speed, centrifugal acceleration is generated, but unlike conventional rocking, excessive acceleration is not generated.

Moreover, since it rotates in one direction, there is little stirring or shaking of the medium, there is no entrainment of air bubbles, and flaw detection can be performed without disturbing the ultrasonic sound field.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 is a plan view showing an embodiment of the probe scanning system of the present invention, and FIG. 8 is a sectional view thereof.

In the embodiment shown in these figures, a part of the strip-shaped test material 1 is immersed in a water tank 3 filled with water as a medium through the side wall of the water tank 3, and the immersed test material 1 is immersed. From above, a plurality of probes 4a, 4b.

...It is applied to a type of flaw detection device that performs flaw detection by emitting ultrasonic waves using 4n.

As in the conventional case, the water tank 3 constituting the flaw detection device includes rubber plates 3a, 3a' and 3b, 3b' for sealing water at the part that penetrates the test material, a water supply pipe (not shown), and an overflow. It is equipped with a tube 5.

Further, a reflecting plate 2 is immersed below the specimen 1 in the water tank 3, substantially parallel to the specimen 1. As will be described later, this reflecting plate 2 is formed in a shape that takes into consideration that the probe is disposed on the circumference and moves on the circumference. In this embodiment, it is formed in an annular shape.

As a means for holding the plurality of probes 4a, 4b, . A rotating ring 9 is provided. The probes 4m, 4b*...4n are mounted on the same circumference of the rotating ring 9 at equal pitches. The lower surface of the rotating ring 9 is immersed in the water in the water tank 3, and the upper surface is connected to a rotating shaft 11, which will be described later, via an arm 10. The rotary ring 9 is supported by the rotating shaft 11 and the arm 10 so as to be parallel to the specimen 1, and as a result, the probes 4m, 4b, ... 4n are aligned in a plane parallel to the specimen 1. held on top.

In addition, the part of the ring 9 that is immersed in water has a probe of 4 m,
4b, . . . 4n are attached and rotate in water, in order to reduce water agitation, it is necessary to design the shape to have as few protrusions as possible.

A driving head 12 shown in FIG. 9 is provided as a means for circularly moving each of the probes 4a, 4b, . . . 4n along the circumference where each of the probes is located. The drive head 12 is provided with a rotating shaft 11 passing through the drive head housing 16 in the vertical direction, and a signal transmission device 17 to the rotating ring 9 is provided within the housing 16. This housing 16 is attached to a flaw detector housing (not shown) or the like via the support member 1g.

The signal transmission device 17 is a means for transmitting and receiving signals to and from the rotating part, and is constructed by appropriately selecting from known means such as an electromagnetic transformer method, a capacitive coupling method, and a slip ring/brush method. In this embodiment, this signal transmission device 17
is the n number of probes 4a, 4 attached to the rotating ring 9.
In order to perform signal transmission and reception with four channels b, . . . , the structure is such that signals for n channels can be transmitted.

The rotating shaft 11 is supported by bearings 13a and 13b, and its lower end is connected to the arm 10, while a pulley 15 is fixed to its upper end, and is connected to a drive motor (not shown) via a belt 14. Concatenated. In addition, this rotating shaft 11
The signal transmission device 17 and each probe 4a, 4b, . . .
・It has a hollow shaft to pass the cable between it and 4n.

A rotating ring 9, which is a means for holding the probes 4a, 4b, . . . 4n, is configured to move linearly relative to the specimen 1. As a means for this purpose, this embodiment includes, for example, a device that winds up the test material 1 using a winding device (not shown) and transports it in the longitudinal direction. However, it is also possible to simply send the test material 1 without winding it up.

Next, the operation of the above embodiment will be explained with reference to FIGS. 7 to 11. Note that FIG. 10 is an explanatory diagram showing a scanning locus according to the scanning method of the present invention, and FIG. 11 is an explanatory diagram showing the relationship between the scanning locus and defects in the longitudinal direction of the inspected material.

In order to scan and detect flaws on a material to be inspected using the scanning method of this embodiment, first, water is supplied as a medium to the water tank 3 and the water level is set to a predetermined level. Note that the medium may be a medium other than human, such as machine oil.

Further, the test material 1 is penetrated through the side wall of the water tank 3 and immersed in the water tank 3.

Next, a signal for exciting the ultrasonic oscillation element is supplied to each probe 4a, 4b, . . . 4n via the signal transmission device 17. Furthermore, when the rotating shaft 11 is rotated at a constant angular velocity by a drive motor (not shown) via the belt 14 and the pulley 15, this causes the rotating ring 9 to move in the direction of the arrow in FIG. 7 via the arm lO. The probes 4a, 4b, . . . , 4n mounted on the circular ring 9 rotate at a constant speed along the circumference of each probe. At the same time, the test material 1 is continuously moved at a constant speed in the direction of the arrow in FIG. 7 by a transport means (not shown).

In this way, a group of scanning trajectories is formed on the entire surface of the specimen 1 by the combination of the constant speed linear motion of the specimen side 1 and the constant speed circular motion of each of the probes 4a, 4b, . . . 4n. Each probe 4a, 4b, . . . 4n performs flaw detection along this trajectory.

FIG. 10 shows the above scanning locus group. As shown in the figure,
The scanning trajectory of each of the probes 4m, 4b, . As a result, the entire surface of the material 1 to be inspected is uniformly scanned and tested, regardless of whether it is in the center or at the edges.

The pitch of the cycloidal curves, that is, the longitudinal distance between adjacent cycloidal curves, is approximately equal to or shorter than the minimum length of the longitudinally elongated defect inherent in the test material 1. Set it so that it looks like this. FIG. 11 shows this condition. This pitch is determined by the rotational speed of the probe and the conveyance speed of the test material.

For example, an example of pitch setting conditions when the minimum length of a defect to be detected is 50 tones is as follows.

Number of probes: 14 Rotating speed: 1 rotation per second Conveying speed: 40 m/min In the above explanation, for flaw detection of strip-shaped materials such as thin steel plates, -
Although the case where the probe-reflection transmission method is used has been described, if the material to be inspected has a certain thickness, it is possible to configure a flaw detection apparatus using the probe-reflection method without changing the configuration of the scanning method of the present invention.

In this case, it is only necessary to change the opening/closing timing settings of the flaw detection gate of the flaw detection device.

In addition, in the embodiments described above, it is assumed that the material to be inspected is conveyed continuously, but if the material to be inspected is relatively short, such as a cut plate of a certain length, the water tank may be moved for a longer time. Then, the entire test material is immersed in a drinking water tank, and the driving head side is moved at a constant speed in the longitudinal direction of the test material while rotating the ring, thereby separating the test material and the drive head. It is also possible to have a configuration in which a group of cycloidal curves is drawn by relatively moving in a straight line.

〔Effect of the invention〕

As explained above, the present invention moves a plurality of probes together with their holding members in a circular motion, moves a specimen to be tested in a relative straight line, and generates a scanning locus consisting of a group of cycloidal curves by combining the circular motions. This structure prevents the movement of the probe from causing excessive acceleration such as reciprocating rocking.
There is no wobbling in the mechanical part, and stable flaw detection can be performed both mechanically and operationally.

Moreover, since the probe moves in a continuous circular motion, there is little stirring or shaking of the medium even when it rotates at high speed, so there is no entrainment of air bubbles, the ultrasonic sound field is not disturbed, and it is stable. flaws can be detected. effective.

Further, according to the present invention, since the pitch of the scanning locus is the same at any position on the material to be inspected, the entire surface can be uniformly detected.

Furthermore, even if the probe is rotated at high speed, it is not affected by air bubbles, so it has the effect of enabling high-density flaw detection.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the principle of the single probe reflection transmission method, Figure 2 is an explanatory diagram showing the reflected wave spectrum in the above flaw detection method, and Figures 3 and 4 are planes showing the conventional probe scanning method. 5 is an explanatory diagram showing the scanning locus according to the conventional method, FIG. 6 is an explanatory diagram showing the relationship between the scanning locus and the minimum defect length in the conventional method, and FIGS.
The figures are a plan view and a sectional view showing an embodiment of the probe scanning method of the present invention, FIG. 9 is a sectional view showing a drive head for circularly moving the probe in the above embodiment, and FIG. 10 is a sectional view of the above embodiment. FIG. 11 is an explanatory diagram showing the relationship between the scanning trajectory and the minimum defect length in the above embodiment. 1...Test material 2...Reflector 3...Water tank 4m, 4b,...4n...Probe 9
...Rotating ring 10...Arm 11...Rotating shaft 12...Drive head 1G...Drive head housing 17...Signal transmission device Applicant Tokyo Co., Ltd. Keiki representative patent attorney Mishina Iwao Figure 1 Figure 2 - G Figure 3 - Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] Part or all of a material to be inspected made of a strip-like material is immersed and held in a medium that propagates ultrasonic waves, and a probe is scanned over the entire surface of the material to be inspected. In the probe scanning method of an ultrasonic flaw detection device, (a) a plurality of probes are arranged at equal pitches on the same circumference, and are placed on a surface parallel to the test material in the medium. (b) rotating means for circularly moving each of the probes along the circumference; and (c) a means for moving the sample to be inspected and the means for holding the probes in a relative straight line. 1. A probe scanning method for flaw detection of a strip material, characterized in that the probe is equipped with a means for moving the material and is configured to draw a group of scanning trajectories at an equal pitch over the entire surface of a material to be inspected.