JP2000230925A - Internal defect detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal defect detecting apparatus capable of detecting an internal defect present in a continuously fed strip-like material continuously and highly accurately with a simple apparatus constitution. SOLUTION: The internal defect detecting apparatus continuously inspects an internal defect of a continuously fed steel strip 1 with its ultrasonic detector. The apparatus is equipped with a liquid tank 4 housing water 6, feed rolls 7-10 guiding the steel strip 1 to pass the same through the water 6, and the ultrasonic flaw detector inspecting the portion of the steel strip 1 immersed in the water 6 in a non-contact state by the detection part 20 arranged in the water 6 according to a pulse reflecting method in transmission type arrangement. The feed rolls 8, 9 coming into contact with the water 6 among the feed rollers 7-10 are wholly immersed in the water 6. Further, a liquid receiver 16 receiving the water falling from the portion of the steel strip 1 issued from the water 6 to prevent the collision thereof with the water 6 in the liquid tank 4 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal part suitable for continuously and accurately detecting internal defects such as non-metallic inclusions inside a strip while conveying the strip such as a steel strip. The present invention relates to a defect detection device.

[0002]

2. Description of the Related Art Inspection of internal defects by ultrasonic waves for the purpose of detecting internal defects such as inclusions over the entire width of a metal plate requires, for example, a large number of ultra-fine defects along the width direction of a rolled metal plate to be inspected. A method in which an ultrasonic probe (detection unit) is fixedly arranged and inspected while transferring a rolled metal plate, or the above-described multiple ultrasonic probes arranged in the width direction of the rolled metal plate are arranged at a right angle to the transfer direction of the rolled metal plate. A method is employed in which a rolled metal plate is transported while scanning is performed.

As the flaw detection method, a pulse reflection method using a dual-purpose probe, a pulse reflection method using a split-type ultrasonic probe, and a transmission method using an ultrasonic probe arranged vertically above and below a plate are conceivable. Among them, in the pulse reflection method and the transmission method using the dual-purpose probe, an ultrasonic probe capable of focusing an ultrasonic beam in a spot shape (spot focus) is used in order to enhance defect detection capability. However, the area that can be inspected by one ultrasonic probe is extremely small, for example, φ1 mm, and there is a problem that an extremely large number of ultrasonic probes are required.

The inventors of the present invention have also proposed a method of solving the above-mentioned problem of the spot focus beam type ultrasonic probe which requires a large number of probes for inspecting the entire board width, as disclosed in Japanese Patent Application Laid-Open No. 7-253414. No. and JP-A-11-8
No. 3815 proposes a flaw detection method and apparatus.
This is because the detection unit of the ultrasonic flaw detector is arranged such that the line-focus type transmission array probe and the line-focus type reception array probe are opposed to each other across the material to be transferred (the direction of the array is the width direction of the material to be measured). ), The reflected wave from the internal defect caused by the ultrasonic wave transmitted from the transmitting array probe is received by the receiving array probe which is arranged opposite to the transmitting array probe, so that the internal defect of the test object can be detected on the front and back surfaces. It is detected without a dead zone immediately below (see FIG. 3).

That is, a 0.5 round trip transmitted wave T1 transmitted from the transmitting array probe and arriving at the receiving array probe by 0.5 reciprocations and the reciprocating 1.5 rounds of the test material to the receiving array probe. The reflected waves F1 and F2 from the defect appearing between the arriving 1.5 round-trip transmitted wave T2 are extracted by the gate circuit, and if the reflected waves are equal to or higher than a predetermined level, it is determined that the defect reflected wave exists and the internal defect is detected ( (See FIG. 7).

In the detection of internal defects using the above-described ultrasonic flaw detector, the water immersion method is used to maintain good acoustic coupling between the ultrasonic probe and the steel plate, that is, to increase the detection accuracy. Conceivable. As the prior art, a water column method disclosed in Japanese Patent Application Laid-Open No. 7-113795 and a water bath immersion method using a pinch roll for sealing disclosed in Japanese Patent Application Laid-Open No. 149929/1993 are exemplified.

[0007]

However, the water column method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. HEI 7-113799 is based on a method in which a number of ultrasonic probes are fixedly arranged in the width direction of a rolled metal plate, and a direction substantially perpendicular to the probe arrangement direction. While transporting the rolled metal plate, multi-channel automatic ultrasonic flaw detection of the rolled metal plate performed by periodically transmitting and receiving ultrasonic waves from each ultrasonic probe,
Alternatively, a number of ultrasonic probes are arranged in the width direction of the rolled metal plate, the rolled metal plate is transported in a direction substantially perpendicular to the probe arrangement direction, and the ultrasonic probe is scanned in a direction substantially perpendicular to the transport direction of the rolled metal plate. Meanwhile, in order to apply to the multi-channel automatic ultrasonic flaw detection of a rolled metal plate performed by periodically transmitting and receiving ultrasonic waves from each ultrasonic probe,
There is a problem as follows.

Since there are a large number of probes, the number of nozzles for forming a water column is large, and the number of parts is large, and the apparatus becomes complicated. For this reason, the equipment cost increases and maintenance becomes troublesome. Further, since the number of nozzles is large, the probability of occurrence of malfunctioning nozzles increases, and the reliability of the apparatus tends to decrease. It is conceivable that a plurality of probes are accommodated in one nozzle. However, when the size of the water column is increased, the force for water diffusion exceeds the surface tension of the water column, and a stable water column cannot be formed.

[0009] Irrespective of the number of probes, the collision of water causes a significant change in the height of the transport path of the rolled metal sheet, which leads to a deterioration in detection accuracy. If the rolled metal sheet is too far away from the nozzle to avoid this, a stable water column cannot be formed. Further, the water bath immersion method using a pinch roll for sealing disclosed in JP-A-5-149929 has the advantage that flaw detection can be carried out without changing the height of the transport path of the rolled metal plate, but the plate can be inspected. When applied to automatic ultrasonic testing of rolled metal sheets that require a high transport speed or high-sensitivity ultrasonic measurement,
The following problems were found.

[0010] The rotation of the upper seal roll, which is partially exposed on the surface of the water, makes it easy for air bubbles to be entrained, thereby causing air bubbles to enter between the ultrasonic probe and the rolled metal plate, causing an error indication. Cheap. Further, the reflected wave from the internal defect in the rolled metal plate may be blocked by air bubbles, and the defect may not be detected. In addition, in terms of equipment, a gap corresponding to the thickness of the rolled metal plate is formed at the longitudinal end sides of the upper and lower sealing pinch rolls (portion through which the rolled metal plate does not pass), and from this portion there is a gap that cannot be ignored. Since water flows out, it is necessary to supply an appropriate amount of water into the tank.

This amount varies depending on the thickness of the rolled metal sheet and the transport speed, and is substantially directly proportional to the thickness of the rolled metal sheet.
The conveying speed is exponentially proportional. Therefore, unless the water supply amount is changed according to the plate thickness and the transport speed,
Since problems such as running out of water from the water tank and overflow of water from the water tank occur, it is necessary to control the water level using a level control device. Also, at this time, if there is a bubble in the supplied water, a problem due to the same bubble as described above occurs,
When the transport speed of the rolled metal sheet is high, a large amount of water needs to be supplied, and a large-scale deaeration facility needs to be provided in the water supply facility.

FIG. 7 of JP-A-5-149929
(Conventional example) shows a method in which the transport path of a rolled metal sheet is changed by a deflector roll, and the rolled metal sheet is immersed in water in a water tank. A large amount of water (an amount that is approximately exponentially proportional to the speed at which the rolled metal sheet is conveyed) falls on the water surface, and the water that adheres to the rolled metal sheet and is taken out of the water surface There is a drawback that bubbles are generated in the water therein, which are caught in the water flow in the water tank and diffused throughout the water tank, thereby causing the same bubble problem as described above. Also, it is assumed that the larger the distance between the deflector roll in the water tank and the water surface, the smaller the possibility of entrainment of air bubbles by the roll, but the specific numerical values are not clear in the past, and especially high-speed conveyance is assumed. If the safety side is designed in such a way, there is also a problem that the water tank becomes deep and the equipment becomes large in size.

The present invention has been made in view of the above-described problems. Even if the conveying speed of a band or the like is increased, internal defects existing in the continuously conveyed band or the like are eliminated. ,
It is an object of the present invention to provide an internal defect detection device that can be detected continuously and with high accuracy with a simple device configuration. Although this device detects internal defects, even surface defects such as slivers, scabs, scale flaws, and gouges are detected if they are due to or contain internal defects. Become.

[0014]

In order to solve the above problems,
The present invention suppresses the entrapment of bubbles during continuous flaw detection in a liquid so as to prevent the occurrence of an erroneous defect indication and the omission of defect detection due to bubbles in order to increase the detection accuracy of the ultrasonic flaw detector. Things. That is, the invention described in claim 1 is an internal defect detection device for continuously inspecting an internal defect of a belt-shaped body that is continuously conveyed by an ultrasonic flaw detection apparatus, wherein a liquid tank containing a liquid is provided. One or more transport rolls for guiding the band and passing through the liquid; and a non-contact inspection of the band immersed in the liquid by a detection unit disposed in the liquid. And a carrier roll that touches the liquid out of the one or more carrier rolls is completely immersed in the liquid and drops from a band-shaped body portion located above the liquid level of the liquid. A shielding means for preventing the liquid from colliding with the liquid in the liquid tank.

The above-mentioned shielding means may be constituted, for example, by a liquid receiver which receives the liquid dropped from the band-shaped body located above the liquid surface and prevents the liquid from colliding with the liquid in the liquid tank. . According to the present invention, the liquid that has fallen toward the liquid in the liquid tank from the band portion above the liquid surface, such as the liquid attached to the band that has come out of the liquid, is shielded by the shielding means such as the liquid receiver. Since direct collision with the liquid is avoided, the generation of bubbles in the liquid in the liquid tank is reduced.

Here, by using the method and apparatus proposed in JP-A-7-253414 and JP-A-11-83815 as an ultrasonic flaw detection method and apparatus, a band-shaped body is compared with a conventional pulse reflection type flaw detection. The dead zone on the front and back surfaces can be reduced. Next, an invention according to claim 2 is an internal defect detection device for continuously inspecting an internal defect of a belt-shaped body that is continuously conveyed by an ultrasonic flaw detector, wherein a liquid tank containing a liquid is provided. And one or more transport rolls for guiding the band and passing through the liquid, and inspecting the band immersed in the liquid in a non-contact manner by a detection unit arranged in the liquid. An ultrasonic flaw detector, wherein the transport roll, which is in contact with the liquid, of the one or more transport rolls is completely immersed in the liquid and the direction of movement of the belt-shaped body from the liquid inside the liquid to the liquid level above An internal defect detection device is provided, wherein the device is guided by the transport roll so that the device is inclined with respect to the vertical direction.

The liquid falling from the strip above the liquid surface is
In general, in consideration of the fact that the strip falls along the strip, the strip that moves upward from the liquid level is tilted from the vertical state, so that the strip upper surface and the liquid removal means (if installed) on the upper face side As a result, the impact force when the falling liquid collides with the liquid surface is reduced as compared with the related art, at least the amount of bubbles generated by the falling liquid on the upper surface side is reduced.

Here, the inclination of the strip is preferably 10 degrees or more with respect to the vertical direction. In addition, it is preferable that the water falling from the liquid removing means on the upper surface of the belt is inclined so as not to directly fall on the liquid surface (so that the water falling from the liquid removing means falls on the upper surface of the belt on the liquid surface). That is, the appropriate inclination angle changes depending on the position and size of the liquid removing unit.

Next, an invention according to a third aspect is an internal defect detection apparatus for continuously inspecting an internal defect of a continuously conveyed band by an ultrasonic flaw detector, wherein the liquid is contained therein. A liquid tank, one or two or more transport rolls that guide the band and pass through the liquid, and a non-contact band portion immersed in the liquid at a detection unit disposed in the liquid. An ultrasonic flaw detector to be inspected in the above, wherein a transport roll that touches the liquid among the one or more transport rolls is completely immersed in the liquid, and the upper end of the fully immersed transport roll and the liquid It is an object of the present invention to provide an internal defect detection device characterized in that a vertical distance from a surface is 5 mm or more.

The further the transport roll in the liquid is separated from the water surface,
Bubble entrainment by the transport roll is reduced. Investigating from this perspective, it is necessary to set the transport rolls deeper in the liquid than necessary by restricting the distance between the transport roll in the fully immersed state and the liquid surface to the minimum necessary distance. And the liquid tank does not become unnecessarily large.

According to a fourth aspect of the present invention, there is provided a method as set forth in any one of the first to third aspects, wherein the liquid adhering to the belt-shaped body portion which has moved upward from the liquid level in the liquid. The liquid removing means for removing the liquid is provided close to the liquid surface. According to the present invention, even if some or all of the removed liquid may fall by removing the liquid attached to the band at a position close to the liquid surface, the drop start height of the liquid is reduced. Approaches liquid level. As a result,
Even if the liquid drops on the liquid surface, the impact force is reduced, and the generation of bubbles is reduced.

Next, the invention according to claim 5 is different from the structure according to any one of claims 1 to 4 in that the entry of the band-like body into the liquid is perpendicular or substantially perpendicular to the liquid level. It is guided by a transport roll so as to be vertical. Here, “perpendicular or substantially perpendicular to the liquid surface” means an angle of about 90 ° ± 15 ° with respect to the liquid surface.

According to the present invention, the angle at which the liquid enters the liquid is perpendicular or substantially perpendicular to the liquid surface, thereby reducing the entrapment of air bubbles when the strip is immersed in the liquid. Note that 9
Up to about 0 ° ± 45 °, there is relatively little bubble entrainment, but the equipment may be large. Next, according to the invention described in claim 6, the configuration according to any one of claims 1 to 5 is provided with a shape correcting means for correcting the shape of the band-like body flat upstream of the liquid tank. It is characterized by the following.

According to the present invention, the belt-like body is warped or stretched,
Even if belly elongation or the like has occurred, the internal defect can be detected with higher accuracy by correcting the shape of the belt-like body to be flat before inspecting with the ultrasonic flaw detector. Further, the flattening of the belt-like body improves the effect of liquid removal by the liquid removing means, and thus improves the effect of suppressing the generation of bubbles.

Next, according to a seventh aspect of the present invention, there is provided a structure according to any one of the first to sixth aspects, wherein a tension in the moving direction is applied to the belt-like body passing through the liquid. It is characterized by including an application means, for example, a bridle roll. ADVANTAGE OF THE INVENTION According to this invention, the tension | tensile_strength is provided in a movement direction and an inspection by an ultrasonic flaw detector is performed in the state where a strip | belt-shaped body is flatter. Further, the flattening of the belt-like body further improves the effect of liquid removal by the liquid removing means, so that the effect of suppressing the generation of bubbles is further improved.

Next, the invention according to claim 8 is the same as the structure according to any one of claims 1 to 7, except that the conveying speed of the belt-like body in the liquid tank is reduced to 1000 m / min or less. It is characterized by doing. According to the present invention, the conveyance speed of the belt-like body passing through the liquid is adjusted to a range in which generation of bubbles is small, so that interference by the bubbles at the time of flaw detection by the ultrasonic flaw detection device is suppressed.

Here, the conveying speed of the belt-like body is 1000 m /
In order to reduce the flow rate to less than or equal to, for example, when a transport means for transporting the strip is provided in the equipment of the flaw detector, the transport speed by the transport means may be adjusted to 1000 m / min or less.
When the flaw detector is used by incorporating it into a line such as an pickling line or a rolling line, the conveyance speed of the band in the line is adjusted by the conveyance device of the band to transfer the band in the liquid tank. The speed may be adjusted to 1000 m / min or less.

The lower limit of the transport speed is not particularly limited because the generation of air bubbles is smaller as the transport speed of the belt-like body is lower. However, if the transport speed is too slow, the time required for flaw detection becomes longer and the efficiency of flaw detection deteriorates. Next, according to a ninth aspect of the present invention, in the configuration according to any one of the first to eighth aspects, the detection unit of the ultrasonic flaw detection apparatus is configured such that the transmitting probe and the receiving probe are transferred. Oppositely placed across the inspection material,
A band-shaped ultrasonic beam focused in one direction is transmitted from the transmission probe, and a reflected wave from an internal defect generated by the ultrasonic beam is received by a reception probe, thereby detecting an internal defect of the test material. A probe pair, wherein a plurality of the probe pairs are arranged along the width direction of the strip.

According to the present invention, by using the above-described detection section (hereinafter also referred to as an ultrasonic line sensor) having a large width that can be inspected by one detection section, the entire width of the band can be detected by a small number of detection sections. The detection can be performed by a unit (probe), and the number of device parts can be reduced. In addition, as said detection part,
Examples described in the above-mentioned JP-A-7-253414 can be exemplified.

Next, a tenth aspect of the present invention is characterized in that, in the configuration according to any one of the first to ninth aspects, the strip is a metal strip.

[0031]

Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the equipment configuration of the internal defect detection device according to the present embodiment, in which a steel strip 1 as a band is arranged from the left side (upper process side) to the right side (lower process side) in FIG. It is conveyed toward.

First, the structure will be described. As shown in FIG. 1, an upstream bridle roll 2, a tension leveler 3, a liquid tank 4, and a downstream bridle roll 5 are arranged from the upstream side to the downstream side. I have. The liquid tank 4 contains liquid water 6. On the upstream side of the liquid tank 4, as shown in FIG. 2, a first transport roll 7 is disposed, and the first transport roll 7 and the second transport roll 8 that is completely immersed in the water 6 form a steel strip. One transport path is changed vertically downward and guided into the water 6 in the liquid tank 4. The steel strip 1 immersed in the water 6 is completely immersed in the water 6 and the second and third transport rolls 8, 9.
, The transport direction is bent in the horizontal direction, and then the third
The transport direction is bent in the vertical direction by the transport roll 9 and the fourth transport roll 10 located above the water surface 6a, and the fluid exits the water 6, that is, the liquid tank 4. Subsequently, the steel strip 1 is transported by the fourth transport roll 10 to the downstream bridle roll 5.
You will be guided to the side.

The distance H between the second and third transport rolls 8 and 9 and the water surface 6a is set to 5 mm or more. Distance H between second and third transport rolls 8 and 9 and water surface 6a
Are separated by 5 mm or more, for example, even if the steel strip 1 is conveyed at 400 m / min, the influence of air bubbles can be greatly reduced. The transport rolls 8 and 9 in the liquid rotate while rubbing a layer of liquid having a thickness corresponding to the rotation speed on the roll surface. When the upper ends of the transport rolls 8 and 9 are above the water surface 6a, the transport rolls 8 and 9 are in water. Once the liquid adhering to the roll surface
Bubbles are generated by ascending to a position higher than the water surface 6a and dropping onto the water surface 6a from there. This causes bubbles to be entrained by the transport roll. Therefore, the layer of liquid dragged by the rotating roll surface forms the water surface 6.
By preventing the carrier from rising to a position higher than a, it is possible to prevent air bubbles from being entrained by the transport roll.
The layer thickness of the liquid dragged by the rotating roll surface changes depending on the roll diameter and the rotation speed of the roll. The larger the roll diameter or the higher the rotation speed, the larger the liquid layer thickness becomes. In the diameter range (φ300 mm to 1500 mm), it was confirmed that the layer thickness can be suppressed to 5 mm or less by controlling the belt-like body conveyance speed to 1000 m / min or less. Therefore, the distance between the upper end of the transport roll and the water surface 6a may be 5 mm or more. Accordingly, it is possible to prevent the liquid tank 4 from becoming unnecessarily deep and the equipment from being enlarged.

If it is not necessary to reduce the size of the equipment, it is of course possible to increase the distance between the upper end of the transport roll and the water surface 6a to, for example, 50 mm. Here, the first and fourth transport rolls 7 and 10 are each composed of two rolls. This is because the height of the transport path of the steel strip 1 is increased once, and And it is not necessarily required.

A probe 20 of the ultrasonic flaw detector, which is a detection unit of the ultrasonic flaw detector, is arranged between the second transport roll 8 and the third transport roll 9. The probe 20 of the ultrasonic flaw detector is shown in FIG.
Transmitter 20a, each consisting of a one-dimensional array probe
And the receiving portion 20b are arranged to face each other across the steel strip 1 in the thickness direction of the steel strip 1. In FIG. 3, reference numeral 11 denotes a line focus beam, and reference numeral 12 denotes a reception beam.

As shown in FIG. 4, a plurality of probes 20 of the ultrasonic flaw detector having the above-described configuration are arranged and arranged along the width direction of the steel strip 1, and the transmitting section 20a and the receiving section 2 are arranged.
0b is supported by the U-shaped frame 13. here,
The reason why the transmitting units 20a and the receiving units 20b are arranged in a zigzag pattern is to enable inspection of the entire width of the steel strip 1 in the width direction while avoiding spatial interference between adjacent sensors. Note that the receiving unit 20b may be arranged on the upper side, and the transmitting unit 20a may be arranged on the lower side. Also, the transmitting unit and the receiving unit are interchanged (for example, the upper side is arranged in the width direction as transmitting unit-receiving unit-transmitting unit..., The lower side is receiving unit-transmitting unit-receiving unit...).
May be arranged).

Each sensor 20 is connected to the flaw detector main body 14. In the flaw detector main body 14, the transmission section 20a transmits the steel strip 1 by 0.5 reciprocation in the thickness direction, and the reception section 20a.
b, a reflected wave F1 from a defect appearing between a 0.5 round-trip transmitted wave T1 arriving at the receiving portion 20b and a 1.5 round-trip transmitted wave T2 arriving at the receiving section 20b after 1.5 round trips of the steel strip 1 in the thickness direction. And F2 are extracted by a gate circuit, and if the level is equal to or higher than a predetermined level, it is detected as an internal defect. The detected internal defect information is supplied to, for example, an upper process or a lower process.

A ringer roll 15 constituting a liquid removing means is disposed between the third transport roll 9 and the fourth transport roll 10 at a position near the water surface 6a. The ringer roll 15 removes the liquid from the steel strip 1 by squeezing the liquid on the surface of the steel strip 1. Further, a liquid receiver 16 constituting a shielding means is disposed between the ringer roll 15 and the water surface 6a. The liquid receiver 16 is a member for receiving the liquid that is directly transmitted from the steel strip 1 through the steel strip 1 or from the linger roll 15 that is the above-described liquid removing means. The liquid receiver 16 may be higher than the water surface 6a, or may be in contact with the water 6 in the liquid tank 4. Further, the water 6 received by the liquid receiver 16 may be gently returned to the water 6 in the liquid tank 4 by, for example, leaving it to overflow, or may be discharged from the liquid receiver 16.

Further, in FIG. 2, a container-like liquid receiver 16 is shown, but the present invention is not limited to this. The liquid receiver may be a flat plate member such as a shielding plate, or a member such as a filter that allows only the liquid to pass therethrough. The liquid receiver is preferably close to the steel strip (10 mm or less). However, when the ratio of the liquid that drops along the liquid removing means is high, it is sufficient that the liquid receiver is located at a position where the liquid can be received. You do not need to be close to the belt. It is also possible to employ a method in which a material (rubber or the like) that does not easily damage the steel strip is provided in the liquid receiver, and this material portion is brought into contact with the steel strip.

The shielding means is not limited to the liquid receiver 16. For example, instead of the liquid receiver 16 or together with the liquid receiver 16, a vacuum suction nozzle is disposed near the surface of the steel strip, and a shielding means, such as suction-eliminating the liquid falling down the steel strip 1, is also effective. Further, the transport speed of the steel strip 1, particularly the transport speed in the liquid tank 4, is adjusted to be 1000 m / min or less. Here, the conveying speed of the steel strip 1 is determined by changing the rotation speed of a motor (not shown) for driving the upstream bridle roll 2, the downstream bridle roll 5, and the conveying rolls 7 to 10 for applying tension to a conventionally known inverter. It can be realized by controlling using such as. Also,
By providing a drive motor only to the bridle rolls 2 and 5 and not providing a drive motor to the transport rolls 7 to 10, the rotation speed of the drive motors of the bridle rolls 2 and 5 is controlled using a conventionally known inverter or the like. Steel strip 1 in liquid tank 4
Can be controlled to 1000 m / min or less.

When the bridle rolls 2 and 5 are not provided, the conveying speed of the steel strip 1 in the continuous upstream process is adjusted so that the conveying speed of the steel strip 1 in the liquid tank 4 is 1000 m / sec.
Minutes so that it does not exceed
10 is provided with a drive motor, and the rotational speed of each of the transport rolls 7 to 10 is adjusted using a conventionally known inverter or the like so that the transport speed of the steel strip 1 in the liquid tank 4 becomes a predetermined speed within 1000 m / min. Should be controlled.

In the internal defect detecting device having the above-described structure, the steel strip 1 is applied with a tensile force of 1000 m / m while being subjected to tensile tension in the direction along the transport direction, that is, in the longitudinal direction, by the upstream bridle roll 2 and the downstream bridle roll 5.
Before being conveyed at a predetermined speed within minutes, and conveyed to the liquid tank 4, it is continuously flattened by the tension leveler 3.
Subsequently, the steel strip 1 enters the water 6 by being guided by the first and second transport rolls 7 and 8 so as to be perpendicular to the water surface 6a and enter the water 6. The generation of bubbles due to air entrainment during immersion is minimized.

Further, the second and third transport rolls 8 and 9
Thus, the steel strip 1 is continuously inspected for internal defects by the ultrasonic flaw detector comprising the probe 20 and the flaw detector main body 14 while moving horizontally in the water 6. Subsequently, the steel strip 1
It moves vertically upward by the third and fourth transport rolls 9 and 10 and exits from the water surface 6a. At this time, the water 6 adhering to the steel strip 1
Is squeezed by the ringer roll 15 near the water surface 6a and surely falls from the height at which the ringer roll 15 is installed.
Can be received at As a result, the dropped liquid is prevented from directly colliding with the water surface 6a, and the generation of bubbles due to the liquid falling from the steel strip 1 above the water surface 6a is prevented.

Here, since the falling liquid is received by the liquid receiver 16, the ringer roll 15 is not necessarily required. However, in order to prevent the water 6 from being transported to the downstream process together with the steel strip 1, Reducing the falling height has the effect of reducing the jump of the liquid that has collided with the liquid receiver 16. In the internal defect detection device of the present embodiment, the entire width of the steel strip 1 in the width direction is inspected while eliminating a dead zone and ensuring a predetermined detection accuracy by using an ultrasonic line sensor as a detection unit of the ultrasonic inspection device. As a target, the number of detection units (sensors) can be reduced.

In addition, the generation of bubbles when the steel strip 1 enters the water 6 and moves upward from the water surface 6a is minimized, and erroneous detection due to bubbles and detection omission due to interference with bubbles are prevented. The detection accuracy is improved. In addition, since the transport rolls 8 and 9 that are in contact with water are all submerged in the water 6,
Entrainment of bubbles due to rotation of the transport rolls 8 and 9 can be prevented.

The liquid removing means is installed at a position close to the water surface 6a as described above. Although specific preferred conditions are affected by the transport speed, the physical properties of the liquid, and the like, it is preferable to set them apart from the water surface within a range of 30 mm to 600 mm. Further, since the steel strip 1 is straightened before the inspection and the inspection is performed in a state where tension is applied, the steel strip 1 becomes flatter and the internal defect of the steel strip 1 is detected with higher accuracy. . Further, the flattening of the steel strip 1 improves the effect of removing the liquid by the ringer roll 15, so that the effect of suppressing the generation of bubbles is improved.

Here, in the above embodiment, the case where the ringer roll 15 is provided as the liquid removing means and the liquid is removed by squeezing the liquid is described. However, other known liquid removing means, for example, a wiper or the like is adopted. It does not matter. When the shape of the belt-like body is flat from the beginning, the tension leveler 3 and the bridle rolls 2 and 5 are not necessarily required, but it is effective to apply tension with a bridle roll or the like to prevent meandering. . Note that the shape correcting means is not limited to the tension leveler, and for example, a temper rolling mill, a roller leveler, or the like may be used. In addition, other known means other than the bridle roll may be used as long as it is a tension applying means. The use of bridle rolls is not limited to the four-roll type shown. For example, a two-roll or three-roll bridle may be used.

Although the water 6 is exemplified as the liquid in the liquid tank 4, the liquid 6 may be selected according to the properties of the target strip.
Other liquids may be used as the liquid therein. Further, in the above-described embodiment, an example is described in which the number of the transport rolls 8 and 9 that are completely immersed in the water 6 is two. However, only one transport roll that is fully immersed in the water 6 may be used. . That is, in the above embodiment, the inspection is performed on the portion of the steel strip 1 which is horizontally transported in the water 6. The inspection may be performed by arranging the probe 20 of the apparatus. However, measuring at a position away from the water surface 6a can reduce the adverse effects of bubbles. Of course, three or more transport rolls for guiding the steel strip 1 in the water 6 may be provided.

Next, a second embodiment will be described with reference to the drawings. It should be noted that the same devices and the like as those in the above-described embodiment are denoted by the same reference numerals and described, and the details are omitted. The basic configuration of this embodiment is the same as that of the first embodiment,
As shown in FIG. 5, the relative position of the third transport roll 9 and the fourth transport roll 10 is changed, and the transport path of the steel strip 1 coming out of the water surface 6a is set to a predetermined direction from the vertical direction (perpendicular to the water surface 6a). It is tilted by the angle θ. The liquid receiver 16 is disposed only on the lower surface side of the steel strip 1.

When the conveying path of the steel strip 1 coming out of the water surface 6a is tilted, the water 6 adhering to the upper surface of the steel strip 1 falls obliquely along the steel strip 1 to reduce the collision force with the water surface 6a. Become
Bubble generation is reduced. Therefore, the liquid receiver 16 on one side
Can be omitted, thereby having the same operation and effect as in the first embodiment. Here, in this embodiment, since the ringer roll 15 as the liquid removing means is provided near the water surface 6a, the generation of bubbles due to the water 6 falling from this point is also reduced.

In all the above embodiments, the steel strip is described as an example of the strip, but the strip is not limited to the steel strip, and a strip made of another metal, for example, It may be a strip made of aluminum, copper, or the like. Further, a belt-like body made of a plastic or the like other than metal may be used. Further, the internal defect detection device of the present embodiment may be used in a single line facility for flaw detection, or may be incorporated as a part of a series of processes for continuously treating a strip, such as an acid washing process. May be used.

[0052]

EXAMPLE An experiment was conducted based on the first embodiment. FIG. 6 shows the result. In this embodiment, as the liquid removing means, a rubber for draining (installed at a position of 30 to 300 mm from the water surface) is used instead of the ringer roll 15, and the steel strip 1 is a hot-rolled steel sheet formed as an endless belt. And transported.

Then, flaw detection was performed using the ultrasonic line sensor 20 in the following four configurations, and the bubble interference area ratio at that time was determined. The bubble interference area ratio indicates the ratio of “the cross-sectional area of the ultrasonic beam that is affected by bubbles” to “the total cross-sectional area of the ultrasonic beam”. (1) The case where the transport roll 9 in the water is not completely immersed (see the symbol A in FIG. 6).

(2) When the transport roll in water is fully immersed with the distance between the water surface 6a and the upper end of the roll being 5 mm (reference B in FIG. 6).
reference). (3) The case where the transport roll in the water is completely immersed, and the shielding plate is disposed on the water surface 6a as the liquid receiver 16 (see reference numeral C in FIG. 6). The shielding plate is a mere flat plate, and does not sufficiently shield the splash of the dropped water.

(4) A case where the container as the liquid receiver 16 is provided by fully submerging the underwater transport roll (see reference numeral D in FIG. 6). The water 6 received by the container is set so as to be discharged to the outside of the liquid tank 4, and the bounce of dropped water is sufficiently shielded. Here, as shown in FIG.
A reflected wave similar to the internal defect is generated in the bubble on the upper surface or the lower surface of the substrate, and is recognized as an internal defect when the amplitude of the reflected wave from the bubble is large. It has also been separately confirmed that if the bubble interference area ratio is within 0.05%, the ultrasonic wave propagation is hardly hindered by the bubbles, and a stable flaw detection with a sensitivity variation within 1 dB is possible. Note that the sensitivity slightly fluctuates and the sensitivity is slightly low (for example, 3 dB).
) May be sufficient if the bubble interference area ratio is within 0.1%. On the other hand, in order to further stabilize the sensitivity, the bubble interference area ratio is preferably within 0.02%.

As can be seen from FIG. 6, if the third transport roll 9 is not fully immersed, the entrapment of air bubbles is large and the steel sheet speed (steel sheet transport speed) is required for stable defect detection.
Is required to be 200 m / min or less, whereas when the third transport roll 9 is completely immersed or a shielding plate for receiving the water 6 is provided, the steel sheet speed can be increased to 300 m / min. . Furthermore, when a container for receiving water 6 is provided, it can be seen that stable defect detection can be performed even when the steel sheet speed is set to 400 m / min or more.

When the steel plate speed was set to 900 m / min for each of the cases denoted by reference characters B to D in FIG. 6, the bubble interference areas were as follows: B: 0.6%, C: 0.5%,
D: 0.042%. That is, when the invention of the first embodiment is adopted, the steel strip 1 is set to 400 m / min or more to 1000 m / min.
While conveying at high speed up to about m / min.
Even if is incorporated in a line that conveys at a high speed of about 400 m / min to about 1000 m / min, it is possible to stably detect defects by using the internal defect detection device according to the present invention. I understand.

In the case of using a hot-rolled steel sheet whose flatness was corrected by a tension leveler in advance, the bubble interference area ratio was reduced by about 20% in any of the above cases. For example, the steel sheet before straightening has a bubble interference area ratio of 0.01
%, The steel sheet after the correction was reduced to about 0.008%. Further, when the steel strip was tilted at an inclination angle of 20 ° from the vertical in the case of the symbol C in FIG. 6, the bubble interference area ratio was reduced by about 20%.

Further, when the depth of the fully submerged roll was changed from 5 mm to 50 mm at B in FIG. 6, the bubble interference area ratio was reduced by about 10%. By the way, for a low steel sheet speed of less than 200 m / min, the first
When the invention of the embodiment is adopted, the bubble interference area ratio is greatly reduced to 0.005% or less. In this case,
Fluctuations in the height of the defect reflected wave due to the interference of the bubbles can be completely ignored, and the accuracy of estimating the size of the defect from the height of the reflected reflected wave can be significantly improved, and the type of the defect can be more accurately determined.
It is significant to adopt the invention of the first embodiment when performing defect detection at a low steel sheet speed of less than 00 m / min.

[0060]

As described above, when the internal defect detecting device of the present invention is employed, the adverse effect of air bubbles when inspecting a continuously conveyed band or the like is greatly reduced, and Even if the transport speed of the body or the like is high, there is an effect that stable internal defects can be detected.

In spite of the above effects, since the apparatus configuration is simple, the number of parts is small and the apparatus does not become large, the apparatus cost can be kept low, and maintenance is easy. Become. That is, when the invention described in claim 1 is adopted, the above-described effect can be obtained with a simple configuration in which the transport roll that touches the liquid is completely immersed in the liquid and a shielding means such as a liquid receiver is provided.

Further, when the invention described in claim 2 is adopted, the above-mentioned effect can be obtained with a simple configuration in which the transport roll that comes into contact with the liquid is completely immersed in the liquid, and the transport path of the belt-like body coming out of the liquid is inclined. be able to. In addition, when the invention described in claim 3 is adopted, the above-described effect can be obtained with a simple configuration in which the transport roll that touches the liquid is completely immersed in the liquid and the depth thereof is regulated.

Further, when the invention described in claim 4 is adopted, there is the effect that the liquid removing means is provided close to the liquid surface and the generation of bubbles can be further reduced. Further, when the invention described in claim 5 is adopted, there is an effect that the generation of bubbles can be further reduced with a simple configuration in which the direction of entry of the band into the liquid is regulated.

Further, when the invention described in claim 6 is adopted, the provision of the shape correcting means has the effect of improving the detection accuracy of the flaw detector and reducing the generation of bubbles.
In addition, when the invention described in claim 7 is adopted, by forming a bridle roll, the band-shaped body becomes more flat, and the detection accuracy in the flaw detector is further improved, and
There is also an effect that generation of bubbles can be further reduced.

Further, when the invention described in claim 8 is adopted, the belt-shaped body is conveyed within the range of the conveyance speed in which the generation of bubbles is small, so that the interference of the bubbles with the defect detection in the flaw detector can be suppressed, and the detection accuracy can be improved. The effect is improved. Claim 9
When the invention described in (1) is adopted, the entire width of the belt-shaped body can be detected by a small number of detection units (probes), and the number of components of the flaw detector can be reduced.

Further, as in the tenth aspect, the internal defect detection device of the present invention is suitable for continuous detection of internal defects in a metal band.

[Brief description of the drawings]

FIG. 1 is a diagram showing a facility configuration of an internal defect detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration around a liquid tank according to the first embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a configuration of a probe of an ultrasonic flaw detector which is a detection unit according to the embodiment of the present invention.

FIG. 4 is a diagram showing an arrangement of probes of the ultrasonic flaw detector according to the embodiment of the present invention.

FIG. 5 is a diagram showing a configuration around a liquid tank according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a steel sheet speed and a bubble interference area ratio.

7A and 7B are diagrams showing a transmitted wave and a reflected wave of a transmission type ultrasonic sensor (ultrasonic line sensor) according to an embodiment of the present invention, and FIG. 7A shows a transmitted wave and a reflected wave from a defect. It is a figure which shows the reflected wave from a bubble.

[Explanation of symbols]

 Reference Signs List 1 steel strip 2, 5 bridle roll 3 tension leveler (shape correcting means) 4 liquid tank 6 water (liquid) 6a water surface 7 first transport roll 8 second transport roll 9 third transport roll 10 fourth transport roll Reference Signs List 15 Ringer roll (liquid removing means) 16 Liquid receiver (shielding means) 20 Ultrasonic probe (detecting part) 20a transmitting part 20b receiving part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Iri 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Chiba Works, Ltd. (72) Inventor Masato Shimizu 2-2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo No. 3 Inside Kawasaki Steel Corporation (72) Inventor Hidenori Miyake 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Chiba Works, Kawasaki Steel Corporation (72) Inventor Norio Tomura 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Address Kawasaki Steel Corporation Chiba Works (72) Inventor Toshihiro Sasaki 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works, (72) Inventor Takaaki Kobashi 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Address Kawasaki Steel Corporation Chiba Works

Claims (10)

[Claims] 1. An internal defect detection device for continuously inspecting an internal defect of a continuously conveyed band by an ultrasonic flaw detector, wherein a liquid tank containing a liquid and a guide for the band are provided. And one or more transport rolls that pass through the liquid, and an ultrasonic flaw detector that non-contactly inspects a band portion immersed in the liquid by a detection unit disposed in the liquid. The transport roll that touches the liquid out of the one or more transport rolls is completely immersed in the liquid, and the liquid that has dropped from the band-shaped body located above the liquid level of the liquid is in the liquid tank. An internal defect detection device provided with shielding means for preventing collision with the liquid. 2. An internal defect detection device for continuously inspecting an internal defect of a continuously conveyed band by an ultrasonic flaw detector, wherein a liquid tank containing a liquid and the band are guided. And one or more transport rolls that pass through the liquid, and an ultrasonic flaw detector that non-contactly inspects a band portion immersed in the liquid by a detection unit disposed in the liquid. The transport roll that touches the liquid among the one or more transport rolls is completely immersed in the liquid, and the direction of movement of the belt-like body from the liquid upward in the liquid level is inclined with respect to the vertical direction. Thus, the internal defect detection device is guided by the transport roll. 3. An internal defect detection device for continuously inspecting an internal defect of a continuously conveyed band by an ultrasonic flaw detector, comprising: a liquid tank containing a liquid; and a guide for guiding the band. And one or more transport rolls that pass through the liquid, and an ultrasonic flaw detector that non-contactly inspects a band portion immersed in the liquid by a detection unit disposed in the liquid. The transport roll that touches the liquid among the one or more transport rolls is fully immersed in the liquid, and the vertical distance between the upper end of the fully immersed transport roll and the liquid surface is 5 mm.
An internal defect detection device characterized by having a diameter of at least mm. 4. A liquid removing means for removing liquid adhering to a belt-like body portion which has moved from a liquid above a liquid surface is provided close to the liquid surface. The internal defect detection device according to any one of the above. 5. The apparatus according to claim 1, wherein said belt-like body is guided by a transport roll so as to be perpendicular or substantially perpendicular to the liquid surface. Internal defect detection device described in 1. 6. The apparatus according to claim 1, further comprising a shape correcting means for correcting the shape of the belt-like body to be flat upstream of the liquid tank.
An internal defect detection device according to claim 5. 7. The internal defect detecting device according to claim 1, further comprising a tension applying means for applying a tensile force in a moving direction to the band passing through the liquid. . 8. The transport speed of the band in the liquid tank is set to 1
The internal defect detection device according to any one of claims 1 to 7, wherein the internal defect detection speed is set to 000 m / min or less. 9. A detection unit of the ultrasonic flaw detection apparatus, wherein a transmission probe and a reception probe are arranged to face each other with a test material to be transferred therebetween, and a band-shaped ultrasonic beam focused in one direction from the transmission probe is formed. A probe pair for transmitting and receiving a reflected wave from an internal defect caused by the ultrasonic beam by a receiving probe, thereby detecting an internal defect of the test material. 9. The internal defect detection device according to claim 1, wherein a plurality of the internal defect detection devices are arranged along the direction. 10. The internal defect detection device according to claim 1, wherein the band is a metal band.