JP7327291B2 - Baffle plate, turbulence suppressor, and method for producing galvanized steel sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a baffle plate for a gas wiping device, a turbulence suppressing device, and a method for manufacturing a plated steel sheet by adjusting the coating weight using the gas wiping device provided with the baffle plate.

In a continuous hot-dip galvanized steel sheet production line as shown in FIG. 1, a steel sheet S that has passed through a continuous annealing furnace in a reducing atmosphere is immersed in a galvanizing bath 2 from a snout 1 . A steel plate S is pulled up in a galvanizing bath 2 along sink rolls 3 and in-bath support rolls 4 (the arrows in FIG. 1 indicate the direction in which the steel plate S advances), and a pair of wiping wiping blades that sandwich the steel plate S are arranged. The gas jetted from the nozzle 5 adjusts the plating thickness to a predetermined thickness. In the method using the wiping nozzle 5, as shown in FIG. 2, the wiping gas 6 is discharged from the wiping nozzle 5 and sprayed onto the surface of the steel sheet S, whereby molten zinc adheres to the surface of the steel sheet S and is pulled up. 7 is wiped to control the required adhesion amount.

In the case of such a method for adjusting the amount of zinc deposited, turbulent flow is generated by the collision of opposing gases jetted from a set of wiping nozzles outside the edge of the steel sheet. This turbulent flow reduces the wiping force at the edge of the steel sheet, resulting in the occurrence of a defect called edge overcoat, in which the amount of zinc adhered to the edge of the steel sheet is greater than that of other areas of the steel sheet. be. From the viewpoint of appearance and shape, the edge overcoat leads to a decrease in yield.

As a method of preventing edge overcoating, there is a method of arranging a baffle plate between a set of wiping nozzles arranged to sandwich the steel plate to avoid gas collision. The effect of the baffle plate is shown in FIGS. 3 and 4. FIG. Without the baffle plate, as shown in FIG. 3A, the opposing wiping gas 6 collides outside the edge of the steel plate S, generating turbulent flow. Due to the influence of this turbulent flow, the collision pressure at the edge of the steel sheet S decreases (FIG. 3(b)), and as a result, the amount of zinc adhered becomes excessive. On the other hand, as shown in FIG. 4A, by providing the baffle plate 8 outside the edge portion of the steel plate S so as to be flush with the steel plate S, it is possible to suppress the turbulence of the airflow (see FIG. 4 (b)). As a result, there is no change in collision pressure, and the amount of zinc deposited can be made uniform.

When the coating thickness is adjusted to a predetermined range by the gas jetted from the wiping nozzle, molten zinc scatters around the steel sheet due to the gas. Therefore, when the baffle plate is brought close to the edge of the steel plate for a long time in order to prevent edge overcoating, there are cases where scattered zinc adheres to the baffle plate and sticks as it is. When the adhering zinc grows large, it causes disturbance of the air flow, resulting in edge overcoat.

Therefore, in Patent Document 1, by changing a part of the material of the baffle plate to Si ₃ N ₄ , the metal adhesion of the molten metal to the baffle plate is greatly reduced, and a method of preventing zinc from sticking is shown. ing.

In Patent Document 2, a movable carriage equipped with a baffle plate that rectifies the gas flow at the edge of the steel strip, the position of which is controlled to follow the edge, and a carriage storage stand for storing the movable carriage when not in operation. , and a rail on which a movable carriage moves (claim 1, etc.).

JP 2012-140693 A JP-A-10-251820

The method disclosed in Patent Document 1 has a certain effect in preventing occurrence of edge overcoat due to zinc adhesion to the baffle plate. However, Si ₃ N ₄ is a ceramic and has an extremely high risk of breakage due to physical impact such as contact with steel plates, wiping nozzles, and maintenance jigs. In addition, when replacing the Si ₃ N ₄ baffle plate when it is damaged, it is necessary to remove the connection plate and the bolt, which makes rapid replacement during operation difficult.

In the method shown in Patent Document 2, during operation, position control is performed so that the movable cart moves on the rail and follows the edge of the steel strip, and during non-operation, the movable cart is moved to the storage stand, and the baffle plate is installed. of the moving device (paragraphs 0011 and 0022 of Patent Document 2).

Here, during operation, steel sheets with different thicknesses are connected and charged into a continuous hot-dip galvanized steel sheet production line. Since the baffle plate can only be replaced from time to time, it is not possible to use a baffle plate with a thickness corresponding to the plate thickness during operation. Moreover, in Patent Documents 1 and 2, even if a problem occurs in the baffle plate during operation, the baffle plate cannot be replaced immediately.

SUMMARY OF THE INVENTION An object of the present invention is to provide a turbulence suppression device capable of exchanging baffle plates even during operation, and a method for manufacturing a plated steel sheet.

The present invention provides means for solving the above problems, and the gist thereof is as follows.

[1] A baffle plate for a gas wiping device that adjusts the amount of plating on the surface of a steel sheet by blowing gas onto the surface of the steel sheet that is lifted out of the plating bath after being immersed in the plating bath,
A baffle plate, wherein the baffle plate is connected to a bracket, and a part of the bracket is detachably attached to the bath equipment.
[2] A method for producing a plated steel sheet, wherein the gas wiping device having the baffle plate according to [1] is used to adjust the coating weight on the surface of the steel sheet to produce the plated steel sheet.
[3] A turbulence suppressing device provided in a gas wiping device that adjusts the amount of plating deposited on a steel plate by injecting wiping gas from gas wiping nozzles arranged oppositely,
a baffle plate;
an attachment/detachment mechanism for switching between a mounting position where the baffle plate is arranged between the gas wiping nozzles arranged opposite to each other and a separated position where the baffle plate is separated from between the gas wiping nozzles;
A turbulence suppressor, comprising:
[4] The attachment/detachment mechanism includes:
A first member having a cylindrical shape, and a second member housed inside the first member and having a cylindrical shape or a rod shape,
A baffle plate is attached to one of the first member and the second member, and the other is fixed to the bath apparatus,
The mounting position is set in a state where the second member is accommodated inside the first member,
The turbulence suppressing device according to [3], wherein the separated position is set in a state in which the second member is pulled out from the first member.
[5] The baffle plate is attached to the second member, a slit is formed in the first member, and the baffle plate attached to the second member is separated from the first member through the slit. The turbulence suppressing device according to [4], characterized by protruding.
[6] The engaging portion between the first member and the second member has a slope inclined from the line edge toward the line center, and the slope is 5 to 30° with respect to the galvanizing liquid surface. The turbulence suppressing device according to [4] or [5], characterized by having an angle (θ1).
[7] The turbulence suppression device according to any one of [3] to [6], wherein the baffle plate has a thickness of −0.5 mm to +0.1 mm with respect to the thickness of the steel plate. .
[8] According to the thickness of the steel plate, the control device according to [7] is characterized by having a control device that switches to a baffle plate having a thickness of −0.5 mm to +0.1 mm with respect to the thickness of the steel plate. Turbulence suppressor.
[9] A method for producing a plated steel sheet, characterized by switching to a baffle plate having a thickness of −0.5 mm to +0.1 mm with respect to the thickness of the steel sheet according to the thickness of the steel sheet.
[10] A method for producing a plated steel sheet, using the turbulence suppressing device according to any one of [1] to [8].

ADVANTAGE OF THE INVENTION In this invention, the manufacturing method of the plated steel plate which manufactures the turbulence suppression apparatus which can replace|exchange a baffle plate also during operation, and a plated steel plate can be provided.

FIG. 1 is a schematic diagram showing a continuous hot-dip galvanized steel sheet production line. FIG. 2 is a schematic diagram showing how the steel sheet is pulled up from the galvanizing bath. FIG. 3(a) is a schematic diagram showing the state of the gas discharged from the wiping nozzle and the steel plate when there is no baffle plate, and FIG. It is a schematic diagram which shows the state of gas. FIG. 4(a) is a schematic diagram showing the state of the gas discharged from the wiping nozzle and the steel plate when a baffle plate is provided, and FIG. 4(b) is a wiping nozzle and baffle plate in the gas wiping device. 2 is a schematic diagram showing the arrangement of , and the state of gas discharged from a wiping nozzle. FIG. FIG. 5 is a schematic diagram showing a conventional baffle plate. FIG. 6 is a schematic diagram showing a baffle plate according to one embodiment of the invention. FIG. 7 is a cross-sectional view showing the relationship between a baffle plate, an inner tubular portion to which it is fixed, and an outer tubular portion to which the inner tubular portion is attached, according to an embodiment of the present invention. FIG. 8 is a schematic diagram showing the flow of wiping gas when using a baffle plate having a thickness different from that of the steel plate. FIG. 9 is a diagram showing the coating weight of the steel plate before and after changing the thickness of the baffle plate.

[Embodiment 1]
The present invention is a turbulence suppressing device provided in a gas wiping device that adjusts the amount of plating deposited on a steel sheet by injecting wiping gas from gas wiping nozzles arranged opposite to each other. This turbulence suppressing device suppresses the turbulence of the wiping gas and the airflow containing the wiping gas, which is generated at the ends of the steel plate in the width direction where the steel plate is not interposed between the gas wiping nozzles arranged opposite to each other. .

The turbulence suppressing device includes a baffle plate, and an attachment/detachment mechanism (described later) that switches between a mounting position in which the baffle plate is arranged between the gas wiping nozzles arranged opposite to each other, and a separated position in which the baffle plate is separated from between the gas wiping nozzles. have The "separated position" is a position where the baffle plate is moved to a replaceable position.

FIG. 6 is a schematic diagram showing a baffle plate according to one embodiment of the invention. As shown in FIG. 6, the baffle plate 11 of the present invention is connected to a bracket 12 (detachment mechanism). A part of the bracket 12 is detachably attached to the equipment 13 on the bath. Here, the equipment 13 on the bath indicates the equipment installed on the hot-dip galvanizing bath, and specifically includes a wiping nozzle (equipment for gas wiping), a support roll (equipment for providing a steel plate pass line, ), an electromagnetic support (equipment for suppressing vibration of the steel plate), and the like.

As shown in FIGS. 7A to 7C, the bracket (attachment/detachment mechanism) 12 has an outer cylinder portion 15 as a first member and an inner cylinder portion 16 as a second member. 7A is a cross-sectional view of the outer cylinder portion 15, FIG. 7B is a cross-sectional view of the inner cylinder portion 16, and FIG. It is sectional drawing which mounted|worn. The outer cylindrical portion 15 is fixed to the bath apparatus. The position of the outer cylinder part 15 in the plate width direction can be adjusted by sliding a part of the bath equipment 13 to which the outer cylinder part 15 is attached in the plate width direction. As shown in FIG. 7( c ), the inner tubular portion 16 is housed inside the outer tubular portion 15 . As shown in FIG. 7B, the baffle plate 11 is fixed below the inner cylindrical portion 16 with bolts. At the mounting position, the baffle plate 11 protrudes outside the outer cylinder portion 15 through a slit formed in the outer cylinder portion 15 and machined in the axial direction of the outer cylinder (see FIGS. 7A and 7C). do.

The bracket (attachment/detachment mechanism) 12 sets the baffle plate to the mounting position by inserting the inner cylinder part 16 into the outer cylinder part 15 , and sets it to the separated position by pulling the inner cylinder part 16 out of the outer cylinder part 15 . In this example, the separated position is a position where the inner tubular portion 16 is pulled out from the outer tubular portion 15 and the baffle plate 11 can be replaced. Since the inner cylindrical portion 16 and the outer cylindrical portion 15 can be accurately processed in the plate thickness direction in units of 0.1 mm before being installed in the manufacturing line, the positions thereof are adjusted in the plate thickness direction in units of 0.1 mm. , can be installed in the production line. Here, since the baffle plate 11 is attached to the outer cylinder portion 15 after being fixed to the inner cylinder portion 16, the inner cylinder portion 16, which has been processed and adjusted with high accuracy, is also adjusted in position with high accuracy. By immediately mounting the baffle plate 11 on the outer cylindrical portion 15, the baffle plate 11 can be immediately installed on the production line in a state of being adjusted in position with high accuracy.

The baffle plate 11 of the present invention may be fixed to the bracket 12, and the fixing method is not particularly limited.

For example, the baffle plate 11 may be fixed to either the first member or the second member of the bracket 12, as shown in FIG. Moreover, if the bath equipment 13 and part of the bracket 12 (in FIG. 6, the inner cylindrical portion 16) are detachably mounted, the mounting method is not particularly limited. For example, as shown in FIG. 6 , a cylindrical outer cylinder 15 is provided at the bottom of the bath equipment 13 , and the outer cylinder 15 is fitted and fixed to the bath equipment 13 . The inner tubular portion 16 is provided so as to be removable from the outer tubular portion 15 . That is, by fitting the inner cylindrical portion 16 of the bracket 12 into the outer cylindrical portion 15 fixed to the bath equipment 13 , a portion of the bracket 12 is detachably attached to the bath equipment 13 .

As described above, the conventional baffle plate is fixed directly to the equipment on the bath with bolts, so there is the problem that it is impossible or takes a long time to replace the baffle plate during operation. However, in the present invention, as shown in FIG. Therefore, even during operation, the baffle plate can be immediately replaced with a new baffle plate by detaching a part of the bracket from the bath equipment.

Here, in order to prevent edge overcoating, it is suitable to equip the thickness of the baffle plate with the thickness of the steel plate. However, conventionally, since thermal deformation of the baffle plate due to the ambient atmosphere and unattached zinc is unavoidable, the thickness of the baffle plate must be about 3 to 4 mm or more, which is difficult to deform. When the thickness is as thin as 2 mm, there is a problem that a certain amount of edge overcoat due to the difference in plate thickness between the baffle plate and the steel plate must be allowed. In addition, as disclosed in Patent Documents 1 and 2, conventional baffle plates could only be replaced during non-operation.

On the other hand, in the present invention, as shown in FIG. 6, the baffle plate 11 is connected to the bracket 12, and a part of the bracket 12 is detachably attached to the equipment 13 on the bath. In particular, the baffle plate can be replaced in about 5 to 10 seconds by detaching a part of the bracket from the equipment on the bath. For example, the baffle plate 11 and the inner cylindrical portion 16 are prepared for each thickness of the steel plate so that the thickness center of the baffle plate and the thickness center of the steel plate are aligned. Specifically, if the steel plate thickness is 2 mm, the 2 mm baffle plate 11 and the inner cylindrical portion 16 having the 2 mm baffle plate 11 are prepared, and if the steel plate thickness is 4 mm, the 4 mm baffle plate 11 is prepared. , an inner cylindrical portion 16 having a baffle plate 11 of 4 mm is prepared. By mounting the inner cylindrical portion 16 having the baffle plates 11 having the respective thicknesses on the outer cylindrical portion 15 according to the plate thickness, it is possible to immediately mount the baffle plates 11 having the thickness corresponding to the plate thickness. can.

In the present invention, a first member having a cylindrical shape (corresponding to the outer cylindrical portion 15) and a second member (corresponding to the inner cylindrical portion 16) having a cylindrical shape or a rod shape and housed inside the first member are provided. Then, the baffle plate is attached to either one of the first member and the second member, and the second member is inserted and removed from the first member, so that the baffle plate is arranged between the gas wiping nozzles arranged oppositely. It is possible to immediately switch between the installed position (solid line) and the spaced position (dotted line) away from between the gas wiping nozzles.

Thus, according to the present invention, since it is possible to immediately replace the baffle plate with a new one, even if zinc adheres to the baffle plate or if the plate thickness changes during operation, It is possible to eliminate edge overcoating immediately, without the need to shut down operations.

Further, in the attachment/detachment mechanism, by configuring the first member to have a cylindrical shape and the second member to be accommodated in the first member, it is possible to reduce the exposure of the sliding portions of both to the plating bath. can be prevented from being alloyed with

Although an example in which the baffle plate is fixed to the second member has been described above, the baffle plate may be fixed to the first member, which is the outer cylindrical portion, and the second member may be fixed to the bath equipment. .

Arbitrary shapes can be used for the shapes of the first member and the second member. Specifically, the first member may be a square tube or a cylinder as long as it has a tubular shape. The second member may have not only a tubular shape such as a cylinder or a rectangular tube, but also a solid bar shape. The second member may have any shape as long as it can be accommodated in the first member.

The material of the baffle plate and bracket is preferably stainless steel, preferably stainless steel containing chromium, nickel and molybdenum, which has low reactivity with zinc and is resistant to thermal deformation, because it prevents zinc from sticking and deformation due to heat. Specific examples of the stainless include SUS316 and SUS316L. Further, in order to prevent deformation, it is desirable to use SUS316L, which has been annealed to remove residual stress.

In addition, alloying with zinc can be prevented by applying a boron nitride-based spray to the surface of the baffle plate and bracket.

Also, considering durability and handling, the thickness of the baffle plate is desirably 2 to 6 mm.

In addition, the cylindrical outer cylinder 15 provided at the bottom of the bath equipment 13 for inserting and removing part of the bracket 12 has an angle of 5 to 30° with respect to the liquid surface of the zinc plating bath 2 (see FIG. 6). of θ ₁ ) is preferably provided. More specifically, the engaging portion between the inner cylinder portion 16 and the outer cylinder portion 15 has a slope that slopes from the line edge toward the line center. The slope has an angle (θ1) of 5 to 30° with respect to the galvanizing liquid surface.

By providing the predetermined angle (θ ₁ ), when the inner cylindrical portion 16 of the bracket 12 is inserted into the outer cylindrical portion 15 of the bath equipment 13, the weight of the bracket 12 allows the bracket 12 to be fixed in the plate width direction. can. The diameter of the outer cylindrical portion 15 of the bath equipment 13 is preferably 10 to 50 mm in consideration of the weight of the bracket 12.

Also, in order to facilitate insertion and removal of the inner cylindrical portion 16 of the bracket 12, it is preferable to provide an angle (θ ₂ ) of 5 to 30° to the handle portion of the handle 17 of the bracket 12. FIG.

As described above, according to the present invention, the baffle plate can be quickly replaced by fixing the baffle plate to a part of the bracket and detachably attaching this part of the bracket to the equipment on the bath. Therefore, even if zinc adheres to the baffle plate, or if the steel plate and the baffle plate come into contact with each other and become deformed or damaged, it is possible to immediately eliminate the occurrence of edge overcoating, and hot-dip galvanizing can be performed without stopping operations. It is possible to manufacture steel sheets. Moreover, the present invention can be applied to the production of various galvanized steel sheets in order to solve the problem of suppressing the generation of edge overcoat, and is not limited to the production of the above hot-dip galvanized steel sheets.

In the present invention, the attachment/detachment mechanism described above enables the thickness of the baffle plate to be adjusted to the thickness of the steel plate to be manufactured sequentially and with high accuracy. I can.

[Embodiment 2]
In Embodiment 1, a set of two baffle plates provided at both ends in the width direction of the steel plate is used. However, if only one set of baffle plates is used, a thickness difference of several millimeters may occur between the thickness of the steel plate and the thickness of the baffle plate, depending on the size of the steel plate to be manufactured. When such a difference in thickness occurs, as shown in FIG. 8, turbulent flow occurs near the edge of the steel sheet, which contributes to deterioration of the edge overcoat.

In Embodiment 2, the turbulence suppression device having the attachment/detachment mechanism of Embodiment 1 is used, and edge overcoat is improved by selectively using baffle plates having a thickness close to the thickness of the steel plate according to the thickness of the steel plate. plan.

As for the material of the baffle plate, it is desirable to use SUS316L or ceramic, which is resistant to thermal deformation, so that it does not deform due to heat even when the thickness is reduced. For SUS316L, it is effective to additionally perform annealing treatment to remove residual stress in order to prevent deformation. Conventionally, the thickness of the baffle plate has been about 3 mm to 4 mm in consideration of deformation, as described above. Since the steel plate is hidden, if the steel plate and the baffle plate are visually aligned, it is difficult to align the center of the steel plate in the thickness direction with the center of the baffle plate in the thickness direction. To address this problem, in the second embodiment, the thickness of the baffle plate is -0.5 mm to +0.1 mm with respect to the thickness of the steel plate.

In the second embodiment, by using the attachment/detachment mechanism of the first embodiment, the effect that the baffle plate can be replaced immediately can be used. It is possible to suppress the occurrence of turbulence in the part with higher accuracy than before. In addition, by aligning the thickness of the baffle plate with the plate thickness, it becomes easy to align and confirm the alignment of the pass line of the steel plate and the baffle plate, and the workability when attaching the baffle plate is also improved.

The baffle plate may be exchanged manually according to the plate thickness, but a control device for exchanging the baffle plate may be provided so that the exchange can be automatically performed by a computer. This controller may be provided inside or outside the turbulence control device.

Embodiment 2 can be implemented as a method of manufacturing a plated steel sheet using a baffle plate having a thickness of −0.5 mm to +0.1 mm with respect to the thickness of the steel sheet.

[Example 1]
A baffle plate according to Embodiment 1 of the present invention (invention example) and a conventional baffle plate (comparative example) were used, respectively, and applied to manufacture of a hot-dip galvanized steel sheet. In the present invention example, when zinc adhered to the baffle plate, it was possible to replace the baffle plate with a new one without stopping the operation. Therefore, it was possible to prevent the occurrence of edge overcoat. On the other hand, when the conventional baffle plate (comparative example) was used, edge overcoating occurred, and the operation was stopped and replaced with a new baffle plate. As a result, the production efficiency was lowered.

[Example 2]
An actual machine test to which Embodiment 2 was applied was conducted in a continuous hot-dip galvanized steel sheet production line.

In the comparative example of the present application, a baffle plate with a thickness of 4 mm was used while a material with a thickness of 2 mm was in operation. In this situation, since the baffle plate is thicker than the steel plate, the pass line of the steel plate is hidden by the baffle plate when the position in the plate thickness direction is confirmed from the side, making it difficult to visually confirm. Therefore, not only are the thicknesses of the steel plate and the baffle plate not uniform, but it is also very difficult to align the position of the baffle plate in the thickness direction of the steel plate with the center of the pass line of the steel plate.

A turbulent flow occurred at the edge of the steel plate due to the misalignment of the steel plate and the baffle plate. As a result, the edge portion of the steel plate had a larger amount of zinc adhered than the center portion of the steel plate, resulting in a so-called edge overcoat state.

Next, as an example of the present invention, the baffle plate was replaced with one having a thickness of 2 mm while the material having a thickness of 2 mm was in operation. The pass line of the steel plate is no longer hidden by the baffle plate, and when the baffle plate is replaced, the pass line of the steel plate and the position of the baffle plate in the thickness direction of the steel plate can be accurately aligned. In addition, by using a baffle plate with a thickness close to the thickness of the steel plate, turbulence at the steel plate edge can be prevented, thereby preventing excessive zinc deposition at the steel plate edge.

Fig. 9 shows the amount of zinc deposited on the steel plate edge and steel plate center when using a 2 mm thick baffle plate and a 4 mm thick baffle plate when using a plate with a thickness of 2 mm and a target zinc coating amount of 144 g/m ² . When using a 2 mm baffle plate, which is about the same thickness as the steel plate corresponding to the conditions of the present invention, for a plate with a thickness of 2 mm, the amount of zinc adhered to the edge of the steel plate is greater than when using a 4 mm thick baffle plate. is close to the target value.

In addition, the present invention can be implemented with a method for manufacturing a plated steel sheet using the turbulence suppressing device described above.

Reference Signs List 1 snout 2 galvanizing bath 3 sink roll 4 in-bath support roll 5 wiping nozzle 6 wiping gas 7 molten zinc 8 baffle plate 9 bath equipment 10 bolt 11 baffle plate 12 bracket 13 bath equipment 14 bolt 15 outer cylinder 16 inner cylinder Part 17 Handle θ ₁ , θ ₂ angle S Steel plate

Claims (4)

A turbulence suppressing device provided in a gas wiping device that adjusts the amount of coating adhered to a steel plate by injecting wiping gas from gas wiping nozzles arranged oppositely,
a baffle plate;
an attachment/detachment mechanism for switching between a mounting position where the baffle plate is arranged between the gas wiping nozzles arranged opposite to each other and a separated position where the baffle plate is separated from between the gas wiping nozzles;
has
The attachment/detachment mechanism includes:
A first member having a cylindrical shape, and a second member housed inside the first member and having a cylindrical shape or a rod shape,
A baffle plate is attached to one of the first member and the second member, and the other is fixed to the bath apparatus,
The mounting position is set in a state in which the second member is accommodated inside the first member,
The separated position is set in a state in which the second member is pulled out from the first member;
The engaging portion between the first member and the second member has a slope that is inclined from the line edge toward the line center, and the slope is at an angle of 5 to 30° (θ1 ), a turbulence suppressing device characterized by having The baffle plate is attached to the second member, a slit is formed in the first member, and the baffle plate attached to the second member protrudes from the first member through the slit. The turbulence suppressing device according to claim 1, characterized by: 3. The turbulence suppression device according to claim 1 , wherein the baffle plate has a thickness of −0.5 mm to +0.1 mm with respect to the thickness of the steel plate. 4. The turbulence suppression according to claim 3 , further comprising a control device that switches to a baffle plate having a thickness of -0.5 mm to +0.1 mm with respect to the thickness of the steel plate according to the thickness of the steel plate. Device.

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