JP4332983B2 - Internal defect detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal defect detection apparatus suitable for continuously and accurately detecting internal defects such as non-metallic inclusions inside a band while conveying a band such as a steel band.
[0002]
[Prior art]
For the purpose of detecting internal defects such as inclusions in the entire width of the metal plate, the inspection of internal defects by ultrasonic waves is performed by, for example, a number of ultrasonic probes (detection units) along the width direction of the rolled metal plate to be inspected. ) Is fixedly arranged and inspected while transporting the rolled metal plate, and the above-mentioned many ultrasonic probes arranged in the width direction of the rolled metal plate are scanned substantially perpendicular to the transport direction of the rolled metal plate, A method of transferring a rolled metal plate is adopted.
[0003]
Examples of the flaw detection method include a pulse reflection method using a transmission / reception probe, a pulse reflection method using a split ultrasonic probe, and a transmission method performed by arranging ultrasonic probes vertically with a plate in between. Among them, in the pulse reflection method and transmission method using a transmission / reception probe, an ultrasonic probe capable of focusing an ultrasonic beam in a spot shape (spot focus) is used in order to improve defect detection capability. However, the area that can be inspected with one ultrasonic probe is extremely small, for example, φ1 mm, and there is a problem that a large number of ultrasonic probes are required.
[0004]
Further, the present inventors have disclosed Japanese Patent Application Laid-Open No. 7-253414 and Japanese Patent Application Laid-Open No. 7-253414 in order to solve the problem of the above-described spot focus beam type ultrasonic probe that requires a large number of probes to inspect the entire plate width. The flaw detection method and apparatus described in Kaihei 11-83815 are proposed.
This is because the detection unit of the ultrasonic flaw detector is arranged so that the line focus type transmission array probe and the line focus type reception array probe are opposed to each other with the test material to be transported in between (the direction of the array is the plate width direction of the test material) By receiving the reflected wave from the internal defect caused by the ultrasonic wave transmitted from the transmitting array probe by the receiving array probe arranged opposite to the transmitting array probe, the internal defect of the test material is detected on the front and back surfaces. The detection is performed without a dead zone immediately below (see FIG. 3).
[0005]
That is, a 0.5 round-trip transmitted wave T1 transmitted from the transmitting array probe and reciprocating 0.5 times through the test material and reaching the receiving array probe and 1.5 reciprocating the test material 1.5 and reaching the receiving array probe .5 The reflected waves F1 and F2 from the defect appearing between the two-way transmitted wave T2 are extracted by the gate circuit, and when the level is equal to or higher than the predetermined level, the internal defect is detected as the defect reflected wave (see FIG. 5). ).
[0006]
By the way, in the detection of internal defects using the ultrasonic flaw detection apparatus as described above, a water immersion method is considered in order to maintain good acoustic coupling between the ultrasonic probe and the test material, that is, to increase detection accuracy. It is done. As the prior art, there are a water column method disclosed in Japanese Patent Application Laid-Open No. 7-113795 and a water bath dipping method using a pinch roll for sealing disclosed in Japanese Patent Application Laid-Open No. 5-149929.
[0007]
[Problems to be solved by the invention]
However, the water column method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-113775 is arranged with a large number of ultrasonic probes fixedly arranged in the width direction of the rolled metal plate, while conveying the rolled metal plate in a direction substantially perpendicular to the probe arrangement direction, Multi-channel automatic ultrasonic inspection of rolled metal plates performed by periodically transmitting and receiving ultrasonic waves from each ultrasonic probe, or arranging a number of ultrasonic probes in the width direction of the rolled metal plate, approximately perpendicular to the probe arrangement direction Of the rolled metal plate carried out by periodically transmitting and receiving ultrasonic waves from each ultrasonic probe while conveying the rolled metal plate in the direction and scanning the ultrasonic probe in a direction substantially perpendicular to the conveying direction of the rolled metal plate. When applied to multi-channel automatic ultrasonic testing, there are the following problems (1) to (3).
[0008]
(1) Since there are a large number of probes, the number of nozzles for forming a water column is large, the number of parts is large, and the apparatus becomes complicated. For this reason, apparatus cost becomes high 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.
(2) It is conceivable to accommodate a plurality of probes in one nozzle. However, when the dimensions of the water column are increased, the force to which water is to diffuse exceeds the surface tension of the water column, so that a stable water column cannot be formed.
[0009]
{Circle around (3)} Regardless of the number of probes, the fluctuation of the height of the transport path of the rolled metal plate becomes remarkable due to the collision of water, and the detection accuracy is deteriorated accordingly. To avoid this, if the rolled metal plate is too far away from the nozzle, a stable water column cannot be formed.
Moreover, although the water bath immersion method using the pinch roll for sealing disclosed in JP-A-5-149929 has an advantage that flaw detection can be carried out without changing the height of the transport path of the rolled metal plate, It has been found that there are the following problems when it is applied to automatic ultrasonic flaw detection of a rolled metal plate that requires a high conveyance speed or high-sensitivity ultrasonic measurement.
[0010]
(1) Bubbles are easily caught in the water by the rotation of the upper seal roll that is partly exposed on the water surface. This causes bubbles to enter between the ultrasonic probe and the rolled metal plate, giving an indication of erroneous defects. Likely to happen. Moreover, the reflected wave from the internal defect in a rolled metal plate may be interrupted by bubbles, and the defect may not be detected.
(2) Also, in terms of equipment, there is a gap corresponding to the thickness of the rolled metal plate on the end in the longitudinal direction of the upper and lower pinch rolls for sealing (the portion through which the rolled metal plate does not pass). Since water flows out so much that it cannot be ignored, it is necessary to supply an appropriate amount of water into the aquarium.
[0011]
This amount varies depending on the thickness and conveying speed of the rolled metal plate, and is approximately directly proportional to the thickness of the rolled metal plate and exponentially proportional to the conveying speed. Therefore, if the supply amount of water is not changed according to the plate thickness and the conveyance speed, problems such as water disappearing from the water tank and water overflowing from the water tank will occur. Therefore, the water level is controlled using the level control device. There is a need. At this time, if there are bubbles in the water to be supplied, the problem due to the bubbles similar to the above (1) occurs. However, when the transport speed of the rolled metal plate is high, a large amount of water needs to be supplied. There has been a problem that a large-scale deaeration facility has to be installed in the facility, and the incidental facility becomes larger.
[0012]
In addition, although FIG. 5 (conventional example) of Unexamined-Japanese-Patent No. 5-149929 shows the method of changing the conveyance path | route of a rolled metal plate with a deflector roll, and immersing a rolled metal plate in the water in a water tank, When the rolled metal plate moves vertically and upwards from the water, a large amount of water adhering to the rolled metal plate and taken out above the water surface is approximately exponentially proportional to the conveying speed of the rolled metal plate. Amount) Bubbles are generated when falling on the water surface, and the bubbles are taken into the water in the water tank. Moreover, air is also involved when the rolled metal plate enters the water, and bubbles are generated. The bubbles taken into these waters are caught in the water flow in the water tank and diffused throughout the water tank, and a part of them moves to the ultrasonic probe side. is there.
[0013]
In addition, it is assumed that the greater the distance between the deflecting roll in the water tank and the water surface, the smaller the possibility of bubble entrainment by the roll. When the safety side is designed, the water tank becomes deep, and there is a problem that an increase in size of the facility is inevitable.
The present invention has been made paying attention to the above-described problems, and even if the transport speed of the belt or the like is increased, the internal defects existing in the belt or the like that is continuously transported can be simplified. It is an object of the present invention to provide an internal defect detection device that can detect continuously and with high accuracy in the device configuration.
[0014]
This device detects internal defects, but even surface defects such as sliver, baldness, scale wrinkles, gouges, etc., are those that are caused by internal defects or contain internal defects. Become.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention mainly prevents the introduction of bubbles to the detection unit position of the flaw detection device, increases the detection accuracy by the ultrasonic flaw detection device, generates an erroneous defect instruction due to the bubbles, and the defect. This prevents the detection omission from occurring.
That is, the invention described in claim 1 is an internal defect detection device that continuously inspects internal defects of a belt-like body that is continuously conveyed with an ultrasonic flaw detector,
A liquid tank in which liquid is stored, one or more transport rolls that guide the band and pass through the liquid, and a band that is immersed in the liquid by a detection unit disposed in the liquid An ultrasonic flaw detector for inspecting a part in a non-contact manner,
Shielding object having a gap through which the bubbles taken in the liquid are prevented from moving to the detection unit side and can pass through the band-like body with respect to at least one of the entrance side and the exit side of the strip form body to the detection unit. And at least the surface of the shield is made of a porous material.
[0016]
There is a possibility that bubbles are generated in the vicinity of the transport roll in contact with the liquid, at a position where the band-like body enters the liquid, and at a position where the band-like body exits the liquid, and the bubbles are taken into the liquid. In particular, the higher the conveying speed of the belt-like body, the more easily bubbles are generated.
On the other hand, according to the present invention, the movement of the bubble to the position of the detection unit of the ultrasonic flaw detector is blocked by the shielding object, and noise of the ultrasonic flaw detection signal due to the bubble is reduced.
[0017]
In addition, there is a possibility that a liquid flow is generated by the movement of the belt-like body in the liquid or the rotation of the transport roll, and the bubbles in the liquid move to the position of the detection unit.
Further, if the surface of the shield is made of a non-porous material such as a steel plate, a fast liquid flow is generated in a gap portion through which the belt-like body passes, and bubbles may be introduced from the gap into the detection unit. . On the other hand, in the present invention, at least the surface of the shielding object is made of a porous material such as a sponge, so that bubbles are trapped on the surface of the shielding object and the bubbles are introduced from the gap to the detection unit side. Is greatly reduced.
[0018]
Here, by using the method and apparatus proposed in Japanese Patent Laid-Open Nos. 7-253414 and 11-83815 as the ultrasonic flaw detection method and apparatus, the front and back surfaces of the band-shaped body can be compared with the conventional pulse reflection type flaw detection. The dead zone is reduced.
Next, the invention described in claim 2 is an internal defect detection device for continuously inspecting an internal defect of a belt-like body continuously conveyed by an ultrasonic flaw detector,
A liquid tank in which liquid is stored, one or more transport rolls that guide the band and pass through the liquid, and a band that is immersed in the liquid by a detection unit disposed in the liquid An ultrasonic flaw detector for inspecting a part in a non-contact manner,
Of the one or two or more transport rolls, the transport roll that touches the liquid is completely immersed in the liquid, and passes through the belt between the transport roll fully immersed in the liquid and the detection unit. A shielding object having a possible gap is provided, and at least the surface of the shielding object is made of a porous material.
[0019]
According to the present invention, entrainment of the transport roll in contact with the liquid reduces the entrainment of bubbles in the liquid due to the rotation of the transport roll.
In addition, there are many air bubbles taken into the liquid in the vicinity of the transport roll that comes into contact with the liquid. However, the air bubbles are prevented from moving to the detection unit position of the ultrasonic flaw detector by the shielding material. Noise of ultrasonic flaw detection signals is reduced.
[0020]
Next, the invention described in claim 3 provides a shielding object having a gap through which the belt-like body can pass between the completely submerged transport roll and the liquid surface, with respect to the configuration described in claim 2. At least the surface of the shield is made of a porous material.
According to the present invention, when the strip enters the liquid or exits from the liquid, the bubbles taken in the liquid are prevented from moving to the transport roll side by the shielding object. As a result, the bubbles moving from the transport roll position to the detection unit side are reduced, and the bubbles introduced to the detection unit position are further reduced. As a result, noise of the ultrasonic flaw detection signal due to bubbles is further reduced.
[0021]
Next, in the invention described in claim 4, with respect to the configuration described in claim 2 or claim 3, the vertical distance between the upper end of the transport roller in the fully immersed state and the liquid surface is 5 mm or more. It is characterized by.
As the transport roll in the liquid is separated from the water surface, the entrainment of bubbles by the transport roll is reduced.
[0022]
By investigating from this viewpoint, it is necessary to set the transport roll deeper in the liquid than necessary by regulating the distance between the transport roll and the liquid level in the fully immersed state to the minimum necessary distance. The liquid tank does not become larger than necessary.
Next, in the invention described in claim 5, in the configuration described in any one of claims 1 to 4, the liquid dropped from the band-shaped body portion located above the liquid surface of the liquid is in the liquid tank. A shielding means for preventing the liquid from colliding with the liquid is provided.
[0023]
The shielding means may be composed of, for example, a liquid receiver that receives the liquid dropped from the strip-like body portion 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 dropped from the band-like body portion above the liquid surface toward the liquid in the liquid tank, such as the liquid adhering to the belt-like body that has come out of the liquid, is removed by the shielding means such as the liquid receiver. Therefore, the occurrence of bubbles on the liquid surface in the liquid tank is reduced.
[0024]
Next, in the invention described in claim 6, the moving direction from the inside of the liquid to the upper surface of the belt in the configuration described in any of claims 1 to 5 is inclined with respect to the vertical direction. Thus, it guides with the said conveyance roll, It is characterized by the above-mentioned.
In view of the fact that the liquid falling from the band-like body portion above the liquid level generally falls along the belt-like body, the belt-like body moving upward from the liquid surface to the liquid surface is tilted from the vertical state, thereby As a result, the impact force when the liquid falling from the liquid removal means on the upper surface side (when installed) collides with the liquid surface is alleviated as compared with the prior art, so that at least the amount of bubbles generated by the falling liquid on the upper surface side is reduced. .
[0025]
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 side of the belt-like body is inclined so that it does not fall directly on the liquid surface (so that the water falling from the liquid removing means falls on the upper surface of the belt-like body on the liquid surface). That is, the appropriate inclination angle varies depending on the position and size of the liquid removing means.
[0026]
Next, the invention described in claim 7 removes the liquid adhering to the band-shaped body portion moved from the liquid to the upper surface of the liquid in the configuration described in any one of claims 1 to 6. The liquid removing means is provided close to the liquid surface.
According to the present invention, even if a part or all of the removed liquid is dropped by removing the liquid adhering to the belt at a position close to the liquid surface, the drop start height of the liquid is Approach the liquid level. As a result, even if the liquid falls on the liquid surface, the impact force is reduced, and the generation of bubbles is reduced.
[0027]
Next, according to an eighth aspect of the present invention, in contrast to the configuration according to any of the first to seventh aspects, the entry of the band into the liquid is perpendicular or substantially perpendicular to the liquid surface. Thus, it is guided by a transport roll.
Here, “perpendicular or substantially perpendicular to the liquid level” means an angle of about 90 ° ± 15 ° with respect to the liquid level.
[0028]
According to the present invention, the entrapment of bubbles when the strip is immersed in the liquid is reduced by setting the angle when entering the liquid to be perpendicular or substantially perpendicular to the liquid surface. Even if tilted to about 90 ° ± 45 °, there is relatively little bubble entrainment, but there is a possibility that the equipment will be larger.
Next, the invention described in claim 9 is provided with a shape correcting means for correcting the shape of the belt-like body to the upstream of the liquid tank in the configuration described in any one of claims 1 to 8. It is characterized by this.
[0029]
According to the present invention, even if warpage, ear extension, abdominal extension, etc. occur in the band-like body, the internal defect is more accurately corrected by correcting the shape of the band-like body flatly before inspecting with the ultrasonic flaw detector. Can be detected.
Further, since the strip-like body is flattened, the effect of removing liquid by the liquid removing means is improved, so that the effect of suppressing the generation of bubbles is improved.
[0030]
Next, a tenth aspect of the present invention is the tension applying means for applying a tensile tension in the moving direction to the band-shaped body passing through the liquid with respect to the configuration described in any of the first to ninth aspects. It is characterized by providing.
According to the present invention, the tensile tension is applied in the moving direction, and the inspection by the ultrasonic flaw detector is performed in a state where the belt-like body is flatter. Furthermore, since the band-like body becomes flatter, the effect of removing the liquid by the liquid removing means is further improved, so that the effect of suppressing bubble generation is further improved.
[0031]
Next, in the invention described in claim 11, in contrast to the configuration described in any one of claims 1 to 10, the belt-like body conveyance speed in the liquid tank is set to 1000 m / min or less. It is a feature.
According to the present invention, since the transport speed of the band-shaped body passing through the liquid is adjusted to a range in which the generation of bubbles is small, the interference by the bubbles during the flaw detection by the ultrasonic flaw detector is suppressed.
[0032]
Here, in order to set the transport speed of the belt-like body to 1000 m / min or less, for example, when the transport means for transporting the strip-like body is provided in the equipment of the flaw detection apparatus, the transport speed by the transport means is 1000 m / min or less. Adjust it. In addition, when the flaw detector is used by being incorporated in a line such as a pickling line or a rolling line, the transport speed of the belt-shaped body in the line is adjusted to transport the belt-shaped body in the liquid tank. What is necessary is just to adjust a speed to 1000 m / min or less.
[0033]
The lower the transport speed, the lower the lower limit value of the transport speed because the lower the transport speed of the belt-like body is, the lower the transport speed is. However, if it is too slow, the time required for flaw detection becomes long and the flaw detection efficiency deteriorates.
Next, according to a twelfth aspect of the present invention, in the configuration described in any one of the first to eleventh aspects, the detection unit of the ultrasonic flaw detector transfers a transmission probe and a reception probe. By placing a specimen-like material facing each other, transmitting a band-shaped ultrasonic beam focused in one direction from the transmission probe, and receiving a reflected wave from an internal defect caused by the ultrasonic beam by a reception probe A probe pair for detecting an internal defect of the test material, wherein a plurality of probe pairs are arranged along the width direction of the belt-like body.
[0034]
According to the present invention, by using the above-described detection unit (hereinafter also referred to as an ultrasonic line sensor) having a large width that can be inspected by one detection unit, the entire width of the band-shaped body is reduced by a small number of detection units (probes). ) Can be detected, and the number of device parts can be reduced.
Examples of the detection unit include those described in JP-A-7-253414.
[0035]
Next, the invention described in claim 13 is characterized in that, in the configuration described in any one of claims 1 to 11, the band-shaped body is a metal band.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an equipment configuration of an internal defect detection device according to the present embodiment, and a steel strip 1 that is a band-like body is moved from the left side (upper process side) to the right side (lower process side) in FIG. It is conveyed toward.
[0037]
First, the configuration 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 toward the downstream side.
The liquid tank 4 contains water 6 that is a liquid. As shown in FIG. 2, a first transport roll 7 is disposed on the upstream side of the liquid tank 4, and the steel strip is formed by the first transport roll 8 and the second transport roll 8 that is completely immersed in the water 6. 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 bent in the horizontal direction in the horizontal direction by the second and third transport rolls 8 and 9 fully immersed in the water 6, and then the third transport roll 9 and The fourth transport roll 10 positioned above the water surface 6a is bent in the transport direction in the vertical direction and exits from the water tank 4, that is, the liquid tank 4. Subsequently, the steel strip 1 is guided to the downstream bridle roll 5 side by the fourth transport roll 10.
[0038]
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. By separating the distance H between the second and third transport rolls 8 and 9 and the water surface 6a by 5 mm or more, for example, even if the steel strip 1 is transported at 400 m / min, the influence of air bubbles is greatly reduced. Can do.
Here, the transport rolls 8 and 9 in the liquid rotate while rubbing a layer of the liquid according to the rotation speed on the roll surface, and when the upper ends of the transport rolls 8 and 9 are above the water surface 6a. When the liquid adhering to the roll surface in water rises to a position higher than the water surface 6a and falls onto the water surface 6a from here, bubbles are generated. This causes air bubbles to be caught by the transport rolls 8 and 9. Therefore, by preventing the liquid layer dragged by the surface of the rotating roll from reaching a position higher than the water surface 6a, entrainment of bubbles by the transport rolls 8 and 9 can be prevented. The layer thickness of the liquid dragged by the rotating roll surface varies depending on the roll diameter and the rotation speed of the rolls 8 and 9, and the larger the roll diameter or the higher the rotation speed, the larger the liquid layer thickness. In the range of the diameters of the typical rolls 8 and 9 (φ300 mm to 1500 mm), it was confirmed that the layer thickness could be suppressed to 5 mm or less by setting the conveying speed of the steel strip 1 to 1000 m / min or less. Therefore, the distance between the upper ends of the transport rolls 8 and 9 and the water surface 6a may be 5 mm or more. Thereby, it can prevent that the liquid tank 4 becomes deeper than needed and an installation enlarges.
[0039]
If it is not necessary to reduce the size of the equipment, it is naturally possible to increase the distance between the upper ends of the transport rolls 8 and 9 and the water surface 6a, for example, 50 mm.
Here, although the 1st and 4th conveyance rolls 7 and 10 are each comprised by two rolls, this is once after raising the height of the conveyance path of the steel strip 1 in the liquid tank 4. It is not necessary to have two.
[0040]
Further, a probe 20 of an ultrasonic flaw detector, which is a detection unit of the ultrasonic flaw detector, is disposed between the second transport roll 8 and the third transport roll 9. As shown in FIG. 3, which is a conceptual diagram, the probe 20 of the ultrasonic flaw detector includes a transmitting unit 20 a and a receiving unit 20 b each made of a one-dimensional array type probe. It is arranged oppositely in the direction. In FIG. 3, reference numeral 11 denotes a line focus beam, and reference numeral 12 denotes a reception beam.
[0041]
As shown in FIG. 4, a plurality of the probes 20 of the ultrasonic flaw detector having the above-described configuration are arranged along the width direction of the steel strip 1, and the arranged transmitting unit 20 a and receiving unit 20 b are U-shaped. The frame 13 is supported. Here, the reason why the transmitting units 20a and the receiving units 20b are arranged in a staggered manner is to enable inspection of the entire width of the steel strip 1 while avoiding space interference between adjacent sensors. is there. The receiving unit 20b may be disposed on the upper side, and the transmitting unit 20a may be disposed on the lower side. Also, the transmitter and receiver are misplaced (for example, the upper side is aligned with the transmitter-receiver-transmitter ... in the width direction, and the lower side is aligned with the receiver-transmitter-receiver ...). May be.
[0042]
Each sensor 20 is connected to the flaw detector main body 14. In the flaw detector main body 14, the 0.5 reciprocating transmitted wave T1 and the steel strip 1 which are transmitted from the transmitting unit 20a and reach the receiving unit 20b by 0.5 reciprocating the steel strip 1 in the plate thickness direction are 1 in the plate thickness direction. .5 The reflected waves F1 and F2 from the defect appearing between the 1.5 round-trip transmitted wave T2 that reciprocates and arrives at the receiving unit 20b are extracted by the gate circuit, and detected as an internal defect when it is above a predetermined level. To do. The detected internal defect information is supplied to, for example, the upper process and the lower process (see FIG. 5).
[0043]
As shown in FIG. 2, shielding plates 30 and 31 made of a porous material are interposed between the transport rolls 8 and 9 in the liquid and the probe 20, respectively. The liquid tank is divided between the transport rolls 8 and 9 and the probe 20. Further, shielding plates 32 and 33 extending in the lateral direction are inserted between the transport rolls 8 and 9 and the liquid level 6a close to the transport rolls 8 and 9, so that the transport rolls 8 and 9 and the liquid level 6a Is also defined by the shielding plates 32 and 33. Thus, in this embodiment, the shielding plates 30 to 33 are disposed in a substantially L shape in a side view so as to surround the transport rolls 8 and 9. However, the shielding plates 30 to 33 are provided with gaps 30a, 31a, 32a and 33a through which the steel strip 1 can pass.
[0044]
In addition, although the said shielding plates 30 and 31 are shielding plates arrange | positioned at the entrance side and exit side of the steel strip 1 with respect to the probe 20, like FIG. 6, the upper end part of the said shielding plates 30 and 31 is water surface. You may abbreviate | omit the shielding plates 32 and 33 extended to the upper direction and extended in the said horizontal direction. In addition, as shown in FIG. 7, when the number of transport rolls 34 submerged is one, for example, the entrance side shield 36 is not arranged between the transport roll 34 and the probe 20 as shown in FIG. 7. Reference numeral 35 denotes a shield interposed between the transport roll 34 and the probe 20. Moreover, the code | symbols 35a and 36a are the clearance gaps for the passage of the steel strip 1 formed in each shield 35 and 36, respectively.
[0045]
Moreover, although it is the example which comprised the shielding object by the flat-shaped shielding plates 30-33 in the said description, a shielding object does not need to be flat plate shape. In short, the shape of the shielding object is not limited as long as it can be shielded.
Moreover, sponge etc. can be illustrated as a porous material which forms the shielding plates 30-33. However, it is preferable that the rigidity and thickness are such that the liquid flow does not oscillate. That is, synthetic fibers and iron nets are suitable. Moreover, the whole shielding object does not need to be porous, and at least the surface may be a porous material.
[0046]
Further, between the third transport roll 9 and the fourth transport roll 10, a ringer roll 15 that constitutes a liquid removing unit is disposed at a position close to the water surface 6a. The ringer roll 15 removes 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 falling directly from the steel strip 1 through the steel strip 1 or from the ringer roll 15 which is the liquid removing means described above. The liquid receiver 16 may be above the water surface 6 a or may be in contact with the water 6 in the liquid tank 4. Further, the water 6 received in the liquid receiver 16 may be gently returned to the water 6 in the liquid tank 4 by means such as leaving it to overflow to the surroundings, or may be discharged from the liquid receiver 16.
[0047]
Moreover, in FIG. 2, although the container-like thing is illustrated as the liquid receptacle 16, it 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 liquid to pass therethrough. The liquid receiver 16 is preferably close to the steel strip 1 (10 mm or less), but when the ratio of the liquid falling through the liquid removing means is high, it may be in a position where it can be received, It does not necessarily need to be close to the steel strip 1. In addition, the material (rubber etc.) which is hard to damage to the steel strip 1 is equipped in the liquid receiver 16, and the method of making this steel part contact the steel strip 1 may be taken.
[0048]
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 in the vicinity of the surface of the steel strip 1, and shielding means such as sucking and removing the liquid falling through the steel strip 1 is also effective. .
Moreover, it has adjusted so that the conveyance speed of the said steel strip 1, especially the conveyance speed in the liquid tank 4 may be 1000 m / min or less. Here, the conveying speed of the steel strip 1 is the same as that of a conventionally known inverter, which is the rotational speed of an upstream bridle roll 2, a downstream bridle roll 5, and a motor (not shown) that drives the conveying rolls 7 to 10 for applying tension. It is realizable by controlling using etc. Further, a drive motor is provided only for the bridle rolls 2 and 5, and no drive motor is provided for the transport rolls 7 to 10, and the rotational speed of the drive motor for the bridle rolls 2 and 5 is controlled using a conventionally known inverter or the like. Thus, it is possible to control the conveying speed of the steel strip 1 in the liquid tank 4 to 1000 m / min or less.
[0049]
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 does not exceed 1000 m / min. Or a drive motor is provided for each of the transport rolls 7 to 10, and each rotational speed of the transport rolls 7 to 10 is transported of the steel strip 1 in the liquid tank 4 using a conventionally known inverter or the like. What is necessary is just to control so that a speed may become predetermined speed within 1000 m / min.
[0050]
In the internal defect detection apparatus configured as described above, the steel strip 1 is within 1000 m / min while tensile tension is applied in the direction along the conveying direction, that is, the longitudinal direction, by the upstream bridle roll 2 and the downstream bridle roll 5. Before being transported at a predetermined speed and transported to the liquid tank 4, it is continuously flattened by the tension leveler 3. Subsequently, the steel strip 1 is guided by the first and second transport rolls 7 and 8 so as to be perpendicular to the water surface 6 a and enter the water 6, whereby the steel strip 1 enters the water 6. Bubble generation due to air entrainment during immersion is minimized. Further, by completely immersing the first and second transport rolls 7 and 8 in the liquid, entrainment of bubbles due to rotation of the transport rolls 7 and 8 is also reduced.
[0051]
Further, the second and third transport rolls 8 and 9 allow the steel strip 1 to continuously detect internal defects in the ultrasonic flaw detector comprising the probe 20 and the flaw detector main body 14 while moving horizontally in the water 6. Inspection is performed.
At this time, even when bubbles are taken into the water 6 when the steel strip 1 enters the water 6, the bubbles are prevented from being captured by the shielding plate 32 and moving toward the transport roll 8. Similarly, even when air bubbles are taken into the water 6 when the steel strip 1 comes out of the water 6, the air bubbles are prevented from being captured by the shielding plate 33 and moving toward the transport roll 9. Furthermore, a water flow is generated by the movement of the steel strip 1 or the first and second transport rolls 7 and 8, and the bubbles existing in the vicinity of the first and second transport rolls 7 and 8 move to the probe 20 side. Although there is a possibility, introduction of bubbles to the probe 20 side is prevented by being blocked by the shielding plates 30 and 31 and being supplemented by the surfaces of the porous shielding plates 30 and 31.
[0052]
Subsequently, the steel strip 1 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 in the vicinity of the water surface 6 a and surely falls from the installation height of the ringer roll 15 and is received by the liquid receiver 16. This prevents the dropped liquid from directly colliding with the water surface 6a and prevents bubbles from being generated by the liquid falling from the steel strip 1 above the water surface 6a.
[0053]
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, the drop height of the liquid By lowering the value, it is possible to reduce the splashing of the liquid colliding with the liquid receiver 16.
In the internal defect detection device of the present embodiment, the entire width of the steel strip 1 is inspected while ensuring a predetermined detection accuracy by eliminating the dead zone by using an ultrasonic line sensor as a detection unit of the ultrasonic flaw detection device. The number of detection units (sensors) may be small as a target.
[0054]
Further, when the steel strip 1 enters the water 6 and moves upward from the water surface 6a, the generation of bubbles is minimized, and the bubbles taken into the water 6 are captured and transported by the shielding plates 32 and 33. The movement to the roll 8.9 side is prevented, and erroneous detection due to air bubbles and detection omission due to air bubble interference are prevented, thereby improving detection accuracy. Further, the generated bubbles are prevented from moving from the position of the transport roll 8.9 to the probe 20 side by the shielding plates 30 and 31, and the detection accuracy is further improved.
[0055]
Further, since the transport rolls 8 and 9 that are in contact with the water 6 are all immersed in the water 6, it is possible to prevent entrainment of bubbles due to the rotation of the transport rolls 8 and 9.
The liquid removing means is installed at a position close to the water surface 6a as described above. Specific preferred conditions are influenced by the conveyance speed, the physical properties of the liquid, and the like, but it is preferable to install them at a distance within a range of 30 mm to 600 mm from the water surface.
[0056]
Furthermore, since the steel strip 1 is corrected and inspected in a state where tension is applied before the inspection, the steel strip 1 becomes flatter and detection of internal defects in the steel strip 1 is performed with higher accuracy. . Further, since the steel strip 1 becomes flatter, the effect of removing liquid by the Ringer roll 15 is improved, and 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 such as a wiper may be employed. Absent.
[0057]
Further, when the shape of the steel strip 1 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 by a bridle roll or the like to prevent meandering. is there. The shape correcting means is not limited to the tension leveler 3, and for example, a temper rolling mill, a roller leveler, or the like may be used. In addition, other known means of the bridle roll may be used as long as it is a tensile tension applying means. Even when a bridle roll is used, it is not limited to the illustrated four-roll type. For example, a 2-roll or 3-roll bridle may be used.
[0058]
Moreover, although the water 6 is illustrated as a liquid in the liquid tank 4, you may use another liquid as a liquid in the liquid tank 4 according to the property of the strip | belt-shaped body made into object.
Moreover, although the said embodiment demonstrated to the example the case where the conveyance rolls 8 and 9 of a fully immersed state are two in the water 6, only one conveyance roll of the fully immersed state in the water 6 may be sufficient. . That is, in the said embodiment, although it inspect | inspects in the part of the steel strip 1 conveyed horizontally in the water 6, if it is in the water 6, the ultrasonic flaw detection will be carried out to the part where the conveyance path of the steel strip 1 is not horizontal. An inspection may be performed by placing the probe 20 of the apparatus (see FIG. 7). However, the adverse effect of bubbles can be reduced by measuring at a position away from the water surface 6a. Of course, three or more transport rolls for guiding the steel strip 1 in the water 6 may be provided.
[0059]
Moreover, in the said embodiment, although the shielding plates 30 and 31 are provided in both the entrance side and exit side of the steel strip 1 with respect to the probe 20, only one shielding plate 30 and 31 may be sufficient. However, it is more effective to provide the shielding plates 30 and 31 on both sides. Further, the shielding plates 32 and 33 are not always necessary.
Next, a second embodiment will be described with reference to the drawings. In addition, the apparatus similar to the said embodiment attaches | subjects and demonstrates the same code | symbol, The detail is abbreviate | omitted.
[0060]
The basic configuration of this embodiment is the same as that of the first embodiment. However, as shown in FIG. 8, the relative position of the third transport roll 9 and the fourth transport roll 10 is changed to change the water surface 6a. The conveyance path of the steel strip 1 coming out of the vehicle is inclined by a predetermined angle θ from the vertical direction (perpendicular to the water surface 6a). Further, the liquid receiver 16 is arranged only on the lower surface side of the steel strip 1.
[0061]
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, thereby reducing the collision force with the water surface 6a and causing bubbles. Occurrence is reduced. Therefore, the liquid receiver 16 on one side can be omitted, and this has the same operation and effect as the first embodiment.
Other configurations, operations, and effects are the same as those in the first embodiment.
[0062]
Here, in this embodiment, since the ringer roll 15 as a liquid removing means is provided in the vicinity of the water surface 6a, the generation of bubbles due to the falling water 6 is also reduced from this point.
In all the above-described embodiments, the steel strip 1 is described as an example of the strip. However, the strip is not limited to the steel strip 1, but a strip made of another metal, for example, aluminum. It may be a belt-like body made of copper or copper. Further, it may be a belt-like body made of plastic other than metal.
[0063]
In addition, the internal defect detection device of the present embodiment may be used in a single line facility for flaw detection, or is incorporated as a part of a series of processes for continuously processing the belt-like body such as a pickling process. May be used.
[0064]
【Example】
An experiment was conducted based on the first embodiment. However, this is an example in the case where the shielding plates 30 to 33 are not provided. FIG. 9 shows the result.
In this embodiment, a draining rubber (installed at a position 30 to 300 mm from the surface of the water) is used in place of the ringer roll 15 as the liquid removing means, and the steel strip 1 is an endless belt. It is the one that is conveyed by circulating.
[0065]
Then, flaw detection was performed using the ultrasonic line sensor 20 with the following four configurations, and the bubble interference area ratio was determined. The bubble interference area ratio represents the ratio of “the cross-sectional area of the ultrasonic beam subjected to bubble interference” to “the total cross-sectional area of the ultrasonic beam”.
(1) When the underwater transport roll 9 is not completely submerged (see symbol A in FIG. 9).
[0066]
(2) The case where the underwater transport roll is completely submerged with a distance of 5 mm from the water surface 6a to the upper end of the roll (see B in FIG. 9).
(3) A case where the underwater transport roll is completely immersed and a shielding plate is disposed on the water surface 6a as the liquid receiver 16 (see C in FIG. 9). In addition, a shielding board is a mere flat plate, and does not fully shield until the dripped water bounces.
[0067]
(4) When the underwater transport roll is completely immersed and a container as the liquid receiver 16 is provided (see reference sign D in FIG. 9). The water 6 received in the container is set so as to be discharged out of the liquid tank 4 and sufficiently shields the splash of the dropped water.
Here, as shown in FIG. 5, the erroneous detection due to the bubble is caused by a bubble on the upper surface or the lower surface of the steel strip 1 and a reflected wave similar to the internal defect is generated, and the internal defect is detected when the amplitude of the reflected wave from the bubble is large. It is recognized as It has also been confirmed separately that if the bubble interference area ratio is within 0.05%, there is almost no hindrance to ultrasonic wave propagation due to bubbles, and stable flaw detection is possible with sensitivity fluctuations within 1 dB. If the sensitivity may vary slightly and the sensitivity may be slightly low (for example, within 3 dB), the bubble interference area ratio may be within 0.1%. On the other hand, in order to further stabilize the sensitivity, the bubble interference area ratio is preferably within 0.02%.
[0068]
As can be seen from FIG. 9 above, if the third transport roll 9 is not completely submerged, entrainment of bubbles is large, and for stable defect detection, the steel plate speed (steel plate transport speed) is 200 m / min or less. On the other hand, when the third conveying roll 9 is completely immersed or a shielding plate for receiving the water 6 is provided, the steel plate speed can be increased up to 300 m / min. Furthermore, when the container which receives the water 6 is provided, it turns out that the stable defect detection can be performed even if the steel plate speed is 400 m / min or more.
[0069]
In addition, for each case indicated by reference signs B to D in FIG. 9, when the steel plate speed was 900 m / min, the bubble interference areas were B: 0.6%, C: 0.5%, and D: 0.042, respectively. %Met.
That is, when the invention of the first embodiment is adopted, the steel strip 1 is conveyed at a high speed of about 400 m / min to about 1000 m / min, or the steel strip 1 is conveyed at a high speed of about 400 m / min to about 1000 m / min. It can be seen that even when incorporated in a line to be transported, defect detection can be performed stably by using the internal defect detection apparatus according to the present invention.
[0070]
In addition, when a hot-rolled steel sheet whose flatness was corrected with a tension leveler in advance was used, the bubble interference area ratio was reduced by about 20% in any of the above cases. For example, in the case of the steel plate before straightening with a bubble interference area ratio of 0.01%, the steel plate after straightening was reduced to about 0.008%.
Further, in the case of reference C in FIG. 9, when the steel strip was tilted by an inclination angle of 20 ° from the vertical, the bubble interference area ratio was reduced by about 20%.
[0071]
Furthermore, when the depth of the fully immersed roll was changed from 5 mm to 50 mm in the symbol B in FIG. 9, the bubble interference area ratio was reduced by about 10%.
By the way, when the invention of the first embodiment is adopted for a low steel plate speed of less than 200 m / min, the bubble interference area ratio is greatly reduced to 0.005% or less. In this case, the fluctuation of the defect reflection wave height due to the bubble interference can be completely ignored, and the accuracy of estimating the defect size from the defect reflection wave height is greatly improved, and the defect type discrimination is highly accurate. In the case where defect detection is performed at a low steel plate speed of less than 200 m / min, it is meaningful to adopt the invention of the first embodiment.
[0072]
In particular, in the present invention, since the shielding objects 30 to 33 are provided in addition to the configuration of the above embodiment, noise due to bubbles is further reduced, and the defect detection accuracy is further improved.
[0073]
【The invention's effect】
As described above, when the internal defect detection device of the present invention is adopted, the bad influence of bubbles is greatly reduced when inspecting the continuously transported strip or the like, and the transport speed of the strip or the like is reduced. Even if it is fast, there is an effect that stable internal defects can be detected.
[0074]
In spite of these effects, since the apparatus configuration is simple, the number of parts is small, the apparatus is not enlarged, the apparatus cost is kept low, and maintenance is easy.
That is, when the invention according to claim 1 is adopted, even when bubbles are taken into the liquid when the band-like body is immersed in the liquid or when the belt-like body comes out of the liquid, and by rotation of the transport roll in contact with the liquid, The shielding object prevents the bubbles from moving to the position of the detection unit of the ultrasonic flaw detector, and has an effect of preventing a reduction in detection sensitivity due to the bubbles.
[0075]
In addition, when the invention according to claim 2 is adopted, the conveyance roll that touches the liquid is completely submerged in the liquid, so that entrainment of bubbles due to rotation of the conveyance roll is reduced, and bubbles in the vicinity of the conveyance roll are detected. This has the effect of preventing movement to the part side and preventing a decrease in detection sensitivity due to bubbles.
At this time, when the invention according to claim 3 is adopted, even if the bubble is taken into the liquid when the strip is immersed in the liquid or when the strip is discharged from the liquid, the bubble is supplemented by the shielding object, and the transport roll By preventing the movement to the side, it is possible to further prevent a decrease in detection sensitivity due to bubbles.
[0076]
Further, when the invention according to claim 4 is adopted, it is possible to more reliably reduce the entrainment of bubbles in the liquid by the transport roll with a simple configuration in which the depth of the transport roll to be completely immersed in the liquid is regulated. Can be obtained.
Further, when the invention according to claim 5 is adopted, it is possible to obtain an effect that the bubbles taken into the liquid are reduced by the strip-like body coming out of the liquid with a simple configuration of providing a shielding means such as a liquid receiver.
[0077]
In addition, when the invention according to claim 6 is adopted, by adopting a simple configuration in which the transport path of the belt-like body that comes out of the liquid is inclined, bubbles taken into the liquid are reduced when the belt-like body comes out of the liquid. An effect can be obtained.
Further, when the invention according to claim 7 is adopted, there is an effect that the bubbles taken into the liquid can be further reduced with a simple configuration in which the liquid removing means is provided close to the liquid surface.
[0078]
In addition, when the invention according to claim 8 is adopted, there is an effect that the bubbles taken into the liquid can be further reduced with a simple configuration in which the direction in which the belt-like body enters the liquid is regulated.
In addition, when the invention according to claim 9 is adopted, by providing the shape correcting means, there is an effect that detection accuracy in the flaw detection apparatus is improved and bubbles taken into the liquid can be reduced.
[0079]
Further, when the invention according to claim 10 is adopted, by providing the tension applying means, the band-like body becomes flatter, the detection accuracy in the flaw detection apparatus is further improved, and the generation of bubbles can be further reduced. There is also an effect.
Further, when the invention according to claim 11 is adopted, the band-shaped body is transported within a transport speed range in which the generation of bubbles is small. As a result, it is possible to suppress the bubbles from interfering with the defect detection in the flaw detection apparatus, and to improve the detection accuracy. There is.
[0080]
Further, when the invention according to claim 12 is adopted, the entire width of the belt-like body can be detected by a small number of detection units (probes), and the number of components of the flaw detection apparatus can be reduced.
As in the invention according to claim 13, the internal defect detection device of the present invention is suitable for continuous flaw detection of internal defects in a metal strip.
[Brief description of the drawings]
FIG. 1 is a diagram showing an equipment configuration of an internal defect detection apparatus 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 as a detection unit according to an embodiment of the present invention.
FIG. 4 is a diagram showing an array of probes of the ultrasonic flaw detector according to the embodiment of the present invention.
FIG. 5 is a diagram showing transmitted waves and reflected waves of an ultrasonic sensor (ultrasonic line sensor) of a transmission type arrangement according to an embodiment of the present invention, and (a) shows transmitted waves and reflected waves from a defect. It is a figure which shows, (b) is a figure which shows the reflected wave from a bubble.
FIG. 6 is a diagram showing another installation example of a shielding plate.
FIG. 7 is a layout example of a shielding plate in the case where there is only one all-in-one transport roll.
FIG. 8 is a diagram showing a configuration around a liquid tank according to a second embodiment of the present invention.
FIG. 9 is a diagram showing the relationship between the steel plate speed and the bubble interference area ratio.
[Explanation of symbols]
1 Steel strip
2,5 Bridle roll
3 Tension leveler (shape correction 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
15 Ringer roll (liquid removing means)
16 Liquid receiver (shielding means)
20 Ultrasonic probe (detector)
20a Transmitter
20b receiver
30 Shield plate (shield)
30a clearance
31 Shield plate (shield)
31a clearance
32 Shield plate (shield)
32a clearance
33 Shield plate (shield) 30a Clearance
33a clearance
34 Transport roll
35 Shield
35a clearance
36 Shield
36a clearance

Claims (13)

An internal defect detection device that continuously inspects internal defects of a belt-like body that is continuously conveyed with an ultrasonic flaw detector,
A liquid tank in which liquid is stored, one or more transport rolls that guide the band and pass through the liquid, and a band that is immersed in the liquid by a detection unit disposed in the liquid An ultrasonic flaw detector for inspecting a part in a non-contact manner,
Shielding object having a gap through which the bubbles taken in the liquid are prevented from moving to the detection unit side and can pass through the band-like body with respect to at least one of the entrance side and the exit side of the strip form body to the detection unit. An internal defect detection device characterized in that at least the surface of the shield is made of a porous material. An internal defect detection device that continuously inspects internal defects of a belt-like body that is continuously conveyed with an ultrasonic flaw detector,
A liquid tank in which liquid is stored, one or more transport rolls that guide the band and pass through the liquid, and a band that is immersed in the liquid by a detection unit disposed in the liquid An ultrasonic flaw detector for inspecting a part in a non-contact manner,
Of the one or two or more transport rolls, the transport roll that touches the liquid is completely immersed in the liquid, and passes through the belt between the transport roll fully immersed in the liquid and the detection unit. An internal defect detection apparatus, characterized in that a shielding object having a possible gap is provided, and at least a surface of the shielding object is made of a porous material. 3. A shielding object having a gap through which a belt-like body can pass is provided between the completely submerged transport roll and the liquid surface, and at least the surface of the shielding object is made of a porous material. The internal defect detection device described in 1. The internal defect detection device according to claim 2 or 3, wherein a distance in the vertical direction between the upper end of the transport roller in the fully immersed state and the liquid surface is 5 mm or more. 5. A shielding means is provided for preventing the liquid dropped from the strip-like body portion located above the liquid surface from colliding with the liquid in the liquid tank. The internal defect detection device described. The internal defect according to any one of claims 1 to 5, wherein the internal defect is guided by the transporting roll so that a moving direction from the liquid to the liquid surface in the belt is inclined with respect to a vertical direction. Detection device. The liquid removing means for removing the liquid adhering to the band-shaped body portion that has moved from the liquid to the upper surface of the liquid is provided close to the liquid surface. Internal defect detection device. The internal defect according to any one of claims 1 to 7, wherein the intrusion of the strip into the liquid is guided by a transport roll so as to be perpendicular or substantially perpendicular to the liquid surface. Detection device. The internal defect detection device according to any one of claims 1 to 8, wherein shape correction means for correcting the shape of the belt-like body to be flat is provided upstream of the liquid tank. The internal defect detection device according to any one of claims 1 to 9, further comprising a tension applying unit that applies a tensile tension in a moving direction to the belt-like body passing through the liquid. The internal defect detection apparatus according to any one of claims 1 to 10, wherein a conveying speed of the belt-like body in the liquid tank is set to 1000 m / min or less. The detection unit of the ultrasonic flaw detection apparatus is disposed so as to face the sample to be transported between the transmission probe and the reception probe, and transmits a band-shaped ultrasonic beam focused in one direction from the transmission probe. A probe pair for detecting an internal defect of a specimen by receiving a reflected wave from an internal defect caused by a sound beam by a receiving probe, and a plurality of the probe pairs are arranged along the width direction of the belt-shaped body. The internal defect detection device according to claim 1, wherein the internal defect detection device is arranged in pieces. The internal defect detection device according to any one of claims 1 to 12, wherein the strip is a metal strip.

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