JP3097253B2 - Ultrasonic flaw detector for band-shaped plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector for a strip-shaped plate, and more particularly to a continuous flow flaw detector suitable for use in online ultrasonic flaw detection of a continuously passed steel strip. The present invention relates to an improvement in an ultrasonic flaw detector for a strip-shaped plate which performs flaw detection by irradiating ultrasonic waves in a thickness direction of the strip-shaped plate to be formed.

[0002]

2. Description of the Related Art As a method of transmitting and receiving ultrasonic waves in the thickness direction of a steel strip continuously passed, as shown in FIG.
Water 14 is sprayed toward the lower surface of the steel strip 10 to form a water column extending from the nozzle 12 to the lower surface of the steel strip 10, and an ultrasonic probe 16 arranged upward in the nozzle 12 transmits ultrasonic waves into the water column. A method is known in which a beam 18 is incident and an ultrasonic wave is transmitted to the steel strip 10.

According to the ultrasonic flaw detector using such a water column, ultrasonic waves can be efficiently transmitted and received to and from a continuously running steel strip.

[0004]

However, when flaw detection is performed by scanning the ultrasonic probe and the water column in the width direction of the plate, if the scanning speed is high, the shape of the water column is disturbed by air resistance or the like. In some cases, ultrasonic waves cannot be transmitted and received accurately. Therefore, there is a problem that the scanning speed is limited and high-speed scanning cannot be performed.

On the other hand, when flaw detection is performed on an individual plate instead of a strip, the plate is immersed in a water tank, and ultrasonic waves are incident downward from an ultrasonic probe disposed above the plate. .

When this water immersion method is applied to ultrasonic inspection of a steel strip running online, as shown in FIG.
An ultrasonic probe 1 in which a part of the pass line of the steel strip 10 is bent downward by the deflector roll 22 and immersed in the water 14 in the water tank 20, and disposed downward near the water surface of the water tank 20.
It is conceivable that the ultrasonic beam 18 enters from FIG.

However, in this method, it is necessary to change the pass line of the current line, and it is not easy to install the existing line. Further, when the pass line is changed, tension is applied to the deflector roll 22, so that a small-diameter roll cannot be used. Is large, and high-precision measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to suppress the variation of the ultrasonic measurement portion without changing the current line.
An object of the present invention is to provide an ultrasonic flaw detector for a strip-shaped plate capable of performing on-line measurement with high accuracy while performing high-speed scanning.

[0009]

SUMMARY OF THE INVENTION The present invention is to prevent liquid leakage in an ultrasonic flaw detection apparatus for a strip-shaped plate which performs ultrasonic detection in a thickness direction of a strip-shaped sheet continuously passed therethrough to perform flaw detection. The pinch rolls for upper and lower seals are provided on the entrance side and the exit side, respectively, for holding the band-like plate while holding the pass line substantially horizontal while the band-like plate is continuously in the liquid. A liquid tank to be immersed, an ultrasonic probe at least a tip of which is immersed in the liquid in the liquid tank, and ultrasonic waves incident in the thickness direction of the band-shaped plate immersed in the same liquid; The object is achieved by providing a means for scanning the acoustic probe in the width direction of the band-shaped plate.

[0010]

According to the present invention, the entrance side and the exit side of the belt-like plate are two
It is pinched by a pinch roll for sealing to prevent liquid leakage from the liquid tank. Therefore, the belt-shaped plate can be continuously immersed in the liquid in the liquid tank without changing the pass line of the current line.

Therefore, at least the tip of the ultrasonic probe is
By immersing in the liquid in the liquid tank, ultrasonic waves can be transmitted and received efficiently.

Further, the ultrasonic probe can scan at a high speed in the width direction of the band-shaped plate.

Further, since there is no need to change the pass line of the current line, installation on the existing line is easy. Furthermore, since the pass line is substantially horizontal, no tension is applied to the sealing pinch rolls on the entrance side and the exit side, and a small-diameter roll can be used. It is possible to suppress the fluctuation of the pass line in a part.

In particular, when a liquid corresponding to the amount of liquid leaking from the vicinity of the pinch roll is constantly injected into the liquid tank and the liquid in the liquid tank is held, the sealing performance around the pinch roll is improved. Is not very expensive and economical.

When an ultrasonic reflecting plate is provided on the bottom surface of the liquid tank, the ultrasonic wave passing through the band plate is re-incident on the band plate, and the intensity of the multiple reflected wave can be increased.

[0016]

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

In the first embodiment of the present invention, as shown in FIG.
Seal each with two upper and lower sealing pinch rolls,
With respect to the lower part and the end face of the sealing pinch roll 32,
A water tank 30 having a gap of about 0.5 mm is installed.

By constantly injecting into the water tank 30 an amount of water that exceeds the amount of water leaking from the gap between the water tank 30 and the pinch roll 32 for sealing, the water level 30A in the water tank 30 is maintained.
Hold.

As shown in FIG. 2, an ultrasonic reflecting plate 34 is disposed on the bottom of the water tank 30, and the ultrasonic beam 18 having passed through the steel strip 10 is re-incident on the steel strip 10 to produce a multiple reflected wave. It is designed to increase strength.

The ultrasonic probe 16 is placed above the water tank 30.
Is disposed such that the downwardly directed tip is immersed in the water in the water tank 30.

As shown in FIG. 3, the ultrasonic probe 16 is scanned by the scanning mechanism 36 over the entire measurement range in the plate width direction in consideration of the meandering of the steel strip 10.

The principle of flaw detection by the ultrasonic probe 16 is described, for example, in Japanese Patent Application Laid-Open No. 1-22, already proposed by the applicant.
Using 9962, the crystal grain orientation distribution of a silicon steel sheet can be measured.

In this case, the difference in crystal orientation can be determined by measuring the intensity difference between the multiple reflected waves.

Next, a second embodiment of the present invention will be described in detail.

The second embodiment is similar to the first embodiment, except that the ultrasonic probe 1 is scanned over the entire width of the steel strip 10.
In addition to 6, an ultrasonic probe 17 for scanning the edge portion of the steel strip 10 at high speed in a small scanning range is added.

The ultrasonic probe 17 for the edge is scanned, for example, as shown in FIG.

In this embodiment, since the edge of the steel strip 10 where the possibility that an abnormal portion exists in the steel strip 10 is high can be scanned at a high speed, the flaw detection of the abnormal portion can be performed with higher accuracy. it can.

In each of the embodiments, the ultrasonic waves are made to pass through the water. However, the type of liquid through which the ultrasonic waves pass is not limited to this. For example, other trace components may be added to water. Or other liquids can be used.

In each of the above embodiments, the crystal orientation of the steel sheet was measured. However, the object to be measured is not limited to this. However, the present invention is applicable.

[0030]

As described above, according to the present invention, the liquid tank can be installed without changing the pass line of the band-shaped plate, and the ultrasonic flaw detector can be easily installed on the existing line.

Since the pass line is substantially horizontal, a small-diameter roll can be used as a pinch roll for sealing.
Since the distance between the pinch rolls can be shortened, it is possible to suppress the fluctuation of the pass line in the ultrasonic measurement portion. That is, at the time of online measurement, in order to ensure measurement accuracy, it is necessary to prevent a decrease in sensitivity, and for that purpose, it is necessary to suppress the fluctuation of the pass line and the inclination of the band-shaped plate. This can be satisfied.

Further, since there is no influence of the disturbance of the water column due to the scanning unlike the water column method, high-speed scanning is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a measurement system according to the first embodiment.

FIG. 3 is a plan view showing a scanning pattern of the ultrasonic probe according to the first embodiment.

FIG. 4 is a perspective view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a plan view showing a scanning pattern of the ultrasonic probe for edge measurement according to the second embodiment.

FIG. 6 is a cross-sectional view showing a configuration of a conventional water column type ultrasonic testing device.

FIG. 7 is a cross-sectional view illustrating an example in which a water tank is installed by bending a pass line of a band-shaped plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Steel strip, 14 ... Water, 16, 17 ... Ultrasonic probe, 18 ... Ultrasonic beam, 30 ... Water tank, 30A ... Water level, 32 ... Pinch roll for sealing, 34 ... Ultrasonic reflecting plate, 36, 37 ... scanning mechanism.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (3)

(57) [Claims] An ultrasonic flaw detector for detecting flaws by irradiating ultrasonic waves in the thickness direction of the strips that are continuously passed through the belt-like plate while holding the band-like plate while preventing liquid leakage. A liquid tank provided with upper and lower sealing pinch rolls on an inlet side and an outlet side, respectively, for keeping the pass line substantially horizontal; a liquid tank for continuously immersing the band-like plate in a liquid; Are immersed in the liquid in the liquid tank, and an ultrasonic probe that irradiates ultrasonic waves in the thickness direction of the band-shaped plate immersed in the same liquid; and A means for scanning in the width direction of the plate; 2. The method according to claim 1, wherein a liquid corresponding to the amount of liquid leaking from around the pinch roll is constantly injected into the liquid tank,
An ultrasonic flaw detector for a strip-shaped plate, wherein the liquid level in the liquid tank is maintained. 3. An ultrasonic flaw detector for a strip-shaped plate according to claim 1, wherein an ultrasonic reflection plate is provided on a bottom surface of said liquid tank.