Baffle plate, turbulence suppression device, and method for manufacturing plated steel sheet

Abstract

To provide a baffle plate that is exchangeable without stopping operation, and a method of manufacturing a plated sheet steel that manufactures a plated sheet steel by adjusting a plating coating weight using a gas wiping device having the baffle plate.SOLUTION: A baffle plate is provided for a gas wiping device that adjusts a plating coating weight on a surface of a sheet steel by immersing the sheet steel in a plating bath and then blowing gas to the surface of the sheet steel being pulled out of the plating bath. A thickness of the baffle plate is -0.5 mm to +0.1 mm relative to a thickness of the sheet steel. The baffle plate is connected to a bracket and a part of the bracket is detachably attached to a bath apparatus.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a baffle plate for a gas wiping device, a turbulence suppression device, and a method for producing a plated steel sheet by adjusting the coating weight using a gas wiping device equipped with this baffle plate. [Background technology]

[0002] 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 zinc plating bath 2 from a snout 1. The steel sheet S is pulled up through the zinc plating bath 2 along a sink roll 3 and a submerged support roll 4 (the arrow in Fig. 1 indicates the direction of travel of the steel sheet S), and the predetermined plating thickness is adjusted by gas ejected from a pair of wiping nozzles 5 arranged on either side of the steel sheet S. In a method using the wiping nozzle 5, as shown in Fig. 2, a wiping gas 6 is ejected from the wiping nozzle 5 and sprayed onto the surface of the steel sheet S to wipe the molten zinc 7 adhering to the surface of the steel sheet S and being pulled up, thereby controlling the amount of adhesion to the required amount.

[0003] In this method of adjusting the amount of zinc coating, turbulence occurs on the outside of the edge of the steel sheet due to the collision of opposing gases ejected from a pair of wiping nozzles. The wiping force of the edge of the steel sheet decreases due to the influence of this turbulence, and as a result, a defect called edge overcoat occurs in which the amount of zinc coating on the edge of the steel sheet is greater than that on the other parts of the steel sheet. From the viewpoint of appearance and shape, edge overcoat leads to a decrease in yield.

[0004] One method to prevent edge overcoating is to place a baffle plate between a pair of wiping nozzles arranged on either side of the steel sheet to prevent gas collision. The effect of the baffle plate is shown in Figures 3 and 4. Without a baffle plate, as shown in Figure 3(a), the opposing wiping gases 6 collide on the outside of the edge of the steel sheet S, generating turbulence. This turbulence reduces the collision pressure on the edge of the steel sheet S (Figure 3(b)), resulting in an excessive amount of zinc deposition. On the other hand, as shown in Figure 4(a), by placing a baffle plate 8 on the outside of the edge of the steel sheet S so that it is flush with the steel sheet S, it is possible to suppress the turbulence of the airflow (Figure 4(b)). As a result, there is no change in the collision pressure, and the amount of zinc deposition can be made uniform.

[0005] When adjusting the plating thickness to a specified range using gas ejected from a wiping nozzle, molten zinc is scattered around the steel sheet by the gas. For this reason, if a baffle plate is brought close to the edge of the steel sheet for a long time to prevent edge overcoating, the scattered zinc may adhere to the baffle plate and become fixed there. If the fixed zinc grows large, it can cause disturbances in the air flow, resulting in edge overcoating.

[0006] Therefore, Patent Document 1 discloses a method in which the material of the baffle plate is partially changed to Si3N4, thereby significantly reducing the metal adhesion of the molten metal to the baffle plate and preventing zinc from sticking.

[0007] Patent document 2 discloses a molten metal plating wiping device (e.g., claim 1) that is equipped with a baffle plate that straightens the gas flow at the edge of a steel strip, a movable carriage whose position is controlled to follow the edge, a carriage storage stand for storing the movable carriage when not in operation, and rails along which the movable carriage moves. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2012-140693 A [Patent Document 2] Japanese Patent Application Publication No. 10-251820 Summary of the Invention [Problem to be solved by the invention]

[0009] The method shown in Patent Document 1 has a certain effect in preventing edge overcoat caused by zinc adhesion to the baffle plate. However, Si3N4 is a ceramic, and there is an extremely high risk of it being damaged by physical impact such as contact with a steel plate, a wiping nozzle, or a maintenance tool. In addition, when replacing a Si3N4 baffle plate after it is damaged, it is necessary to remove the connecting plate and bolts, making it difficult to quickly replace it during operation.

[0010] In the method shown in Patent Document 2, during operation, the mobile cart moves on a rail and is position-controlled to follow the edge of the steel strip, and during non-operational times, the mobile cart is moved to a storage stand and the baffle plate moving device is replaced (Patent Document 2, specification, paragraphs 0011 and 0022).

[0011] Here, during operation, steel sheets of different thicknesses are charged in a connected state into a continuous hot-dip galvanized steel sheet production line, but in both the methods of Patent Document 1 and Patent Document 2, the baffle plate can only be replaced during non-operation, so a baffle plate of a thickness corresponding to the sheet thickness cannot be used during operation. Moreover, in Patent Documents 1 and 2, even if a defect occurs in the baffle plate during operation, the baffle plate cannot be replaced immediately.

[0012] An object of the present invention is to provide a turbulence suppression device that allows replacement of a baffle plate even during operation, and a method for producing a plated steel sheet. [Means for solving the problem]

[0013] The present invention provides a means for solving the above problems, and the gist of the invention is as follows. [1] A baffle plate for a gas wiping device that adjusts the coating weight of a steel sheet surface by blowing gas onto the surface of the steel sheet that is immersed in the coating bath and then pulled out of the coating bath, A baffle plate, characterized in that the baffle plate is connected to a bracket, and a portion of the bracket is removably attached to a bath equipment. [2] A method for producing plated steel sheet, comprising using a gas wiping device equipped with the baffle plate described in [1] to adjust the coating weight on the steel sheet surface to produce a plated steel sheet. [3] A turbulence suppression device provided in a gas wiping device that adjusts the coating weight of a steel sheet by spraying a wiping gas from gas wiping nozzles arranged opposite to the gas wiping nozzle, A baffle plate; a mounting mechanism for switching the baffle plate between a mounting position in which the baffle plate is disposed between the gas wiping nozzles arranged opposite to each other and a separated position in which the baffle plate is separated from the gas wiping nozzles; A turbulence suppression device comprising: [4] The attachment / detachment mechanism includes: The device includes a first member having a cylindrical shape, and a second member having a cylindrical or rod shape and housed inside the first member, A baffle plate is attached to one of the first member and the second member, and the other is fixed to the bath device; The second member is accommodated inside the first member in the mounting position, The turbulence suppression device according to [3], characterized in that the second member is pulled out from the first member to set the separated position. [5] A turbulence suppression device as described in [4], characterized in that 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. [6] A turbulence suppression device as described in [4] or [5], characterized in that the engagement portion between the first member and the second member has a slope that slopes from the line edge toward the line center, and the slope has an angle (θ1) of 5 to 30° with respect to the zinc plating liquid surface. [7] The turbulence suppression device according to any one of [3] to [6], wherein the thickness of the baffle plate is -0.5 mm to +0.1 mm relative to the thickness of the steel plate. [8] The turbulence suppression device according to [7], further comprising a control device for switching between baffle plates having a thickness of -0.5 mm to +0.1 mm relative to the thickness of the steel plate depending on the thickness of the steel plate. [9] A method for manufacturing a plated steel sheet, comprising: switching to a baffle plate having a thickness of -0.5 mm to +0.1 mm relative to the thickness of the steel sheet depending on the thickness of the steel sheet.

[10] A method for producing a plated steel sheet, characterized by using a turbulence suppression device described in any one of [3] to [8]. Effect of the Invention

[0014] The present invention can provide a turbulence suppression device that allows replacement of a baffle plate even during operation, and a method for producing a plated steel sheet. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing a continuous hot-dip galvanized steel sheet production line. [Diagram 2] FIG. 2 is a schematic diagram showing how a steel sheet is pulled up from a zinc plating bath. [Diagram 3] 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. 3(b) is a schematic diagram showing the state of the gas discharged from the wiping nozzle in a gas wiping device. [Figure 4]Figure 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 Figure 4(b) is a schematic diagram showing the arrangement of the wiping nozzle and baffle plate in a gas wiping device and the state of the gas discharged from the wiping nozzle. [Diagram 5] FIG. 5 is a schematic diagram showing a conventional baffle plate. [Figure 6] FIG. 6 is a schematic diagram showing a baffle plate according to one embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing the relationship between the baffle plate according to one embodiment of the present invention, the inner cylindrical part to which it is fixed, and the outer cylindrical part to which the inner cylindrical part is attached. [Figure 8] FIG. 8 is a schematic diagram showing the flow of wiping gas when a baffle plate having a thickness different from the thickness of the steel plate is used. [Figure 9] FIG. 9 is a diagram showing the coating weight of the steel sheet before and after changing the thickness of the baffle plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Embodiment 1] The present invention relates to a turbulence suppression device provided in a gas wiping device that adjusts the coating weight of a steel sheet by spraying a wiping gas from gas wiping nozzles arranged opposite to the nozzles. This turbulence suppression device suppresses turbulence of the wiping gas and airflow containing the wiping gas that occurs at the end of the steel sheet in the width direction where the steel sheet is not interposed between the gas wiping nozzles arranged opposite to the nozzles.

[0017] The turbulence suppression device has a baffle plate and a detachment mechanism (described later) that switches the baffle plate between an attached position where the baffle plate is disposed between the gas wiping nozzles arranged opposite to each other and a remote position where the baffle plate is separated from the gas wiping nozzles. The "remote position" is a position where the baffle plate is moved to a position where it can be replaced.

[0018] Fig. 6 is a schematic diagram showing a baffle plate according to one embodiment of the present invention. As shown in Fig. 6, a baffle plate 11 of the present invention is connected to a bracket 12 (attaching / detaching mechanism). A part of the bracket 12 is detachably attached to above-bath equipment 13. Here, above-bath equipment 13 refers to equipment installed above the hot-dip galvanizing bath, and specifically can be a wiping nozzle (equipment for gas wiping), a support roll (equipment for creating a pass line for the steel sheet), an electromagnetic support (equipment for suppressing vibration of the steel sheet), etc.

[0019] As shown in Figs. 7(a) to (c), the bracket (attaching / detaching mechanism) 12 has an outer cylinder 15 as a first member and an inner cylinder 16 as a second member. Fig. 7(a) is a cross-sectional view of the outer cylinder 15, Fig. 7(b) is a cross-sectional view of the inner cylinder 16, and Fig. 7(c) is a cross-sectional view of the inner cylinder 16 attached to the outer cylinder 15. The outer cylinder 15 is fixed to the bathing device. The position of the outer cylinder 15 in the plate width direction can be adjusted by sliding a part of the bathing device 13 to which the outer cylinder 15 is attached in the plate width direction. As shown in Fig. 7(c), the inner cylinder 16 is accommodated inside the outer cylinder 15. As shown in Fig. 7(b), a baffle plate 11 is fixed to the lower part of the inner cylinder 16 by a bolt. In the mounted position, the baffle plate 11 protrudes outward from the outer tubular portion 15 through slits (see FIGS. 7(a) and (c)) machined in the axial direction of the outer tubular portion 15.

[0020] The bracket (attaching / detaching mechanism) 12 sets the baffle plate to the attached position by inserting the inner cylinder part 16 into the outer cylinder part 15, and sets the baffle plate to the separated position by pulling out the inner cylinder part 16 from the outer cylinder part 15. In this example, the separated position is a position where the inner cylinder part 16 is pulled out from the outer cylinder part 15 and the baffle plate 11 can be replaced. Since the inner cylinder part 16 and the outer cylinder part 15 can be precisely machined in units of 0.1 mm in the plate thickness direction before being installed on the manufacturing line, the position can be adjusted in units of 0.1 mm in the plate thickness direction and installed on the manufacturing line. Here, the baffle plate 11 is attached to the outer cylinder part 15 after being fixed to the inner cylinder part 16. Therefore, the inner cylinder part 16, which has been machined and adjusted in position with high precision, is immediately attached to the outer cylinder part 15, which has also been adjusted in position with high precision, and the baffle plate 11 can also be immediately installed on the manufacturing line in a state where its position has been adjusted with high precision.

[0021] The baffle plate 11 of the present invention only needs to be fixed to the bracket 12, and the fixing method is not particularly limited.

[0022] For example, as shown in FIG. 6, the baffle plate 11 may be fixed to either the first member or the second member of the bracket 12. Also, as long as the above-bath equipment 13 and a part of the bracket 12 (the inner cylinder part 16 in FIG. 6) are attached in a detachable manner, there is no particular limitation on the method of attachment. For example, as shown in FIG. 6, a cylindrical outer cylinder part 15 is provided at the bottom of the above-bath equipment 13, and the outer cylinder part 15 is fitted and fixed to the above-bath equipment 13. The inner cylinder part 16 is provided so as to be removable from the outer cylinder part 15. That is, the inner cylinder part 16 of the bracket 12 is fitted into the outer cylinder part 15 fixed to the above-bath equipment 13, so that a part of the bracket 12 is attached in a detachable manner from the above-bath equipment 13.

[0023] As described above, the conventional baffle plate is fixed directly to the above-bath equipment with bolts, which makes it impossible or time-consuming to replace the baffle plate during operation. However, in the present invention, as shown in Fig. 6, the baffle plate 11 is fixed to the bracket 12, and a part of the bracket 12 to which the baffle plate 11 is fixed is installed so as to be detachable from the above-bath equipment 13. Therefore, even during operation, the baffle plate can be instantly replaced with a new one by detaching a part of the bracket from the above-bath equipment.

[0024] Here, in order to prevent edge overcoat, it is appropriate to have the thickness of the baffle plate equal to the thickness of the steel plate. However, in the past, since thermal deformation of the baffle plate caused by the surrounding atmosphere or non-adhered zinc is inevitable, the thickness of the baffle plate must be made less likely to deform, about 3 to 4 mm or more, and when the thickness of the steel plate is thin, such as 2 mm, there was a problem that a certain degree of edge overcoat caused by the difference in thickness between the baffle plate and the steel plate must be tolerated. In addition, as disclosed in Patent Document 1 or 2, the conventional baffle plate could only be replaced during non-operation.

[0025] In contrast, 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 bath equipment 13. Therefore, even during operation, the baffle plate can be replaced in about 5 to 10 seconds by detaching a part of the bracket from the bath equipment. For example, the baffle plate 11 and the inner cylinder 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 thickness of the steel plate is 2 mm, a baffle plate 11 of 2 mm and an inner cylinder 16 with a baffle plate 11 of 2 mm attached thereto are prepared, and if the thickness of the steel plate is 4 mm, a baffle plate 11 of 4 mm and an inner cylinder 16 with a baffle plate 11 of 4 mm attached thereto are prepared. Then, by attaching the inner cylinder 16 with the baffle plate 11 of each thickness attached to the outer cylinder 15 according to the plate thickness, the baffle plate 11 of the thickness according to the plate thickness can be immediately attached.

[0026] The present invention has a cylindrical first member (corresponding to outer cylindrical portion 15) and a cylindrical or rod-shaped second member (corresponding to inner cylindrical portion 16) housed inside the first member, and a baffle plate is attached to either the first member or the second member.By inserting or removing the second member into or from the first member, the baffle plate can be instantly switched between an attached position (solid line) in which it is arranged between opposing gas wiping nozzles, and a separated position (dotted line) separated from between the gas wiping nozzles.

[0027] In this way, according to the present invention, the baffle plate can be immediately replaced with a new one, so that even if zinc adheres to the baffle plate or the plate thickness is changed during operation, it is possible to immediately eliminate the occurrence of edge overcoating during operation, and there is no need to stop operation.

[0028] Furthermore, in the attachment / detachment mechanism, by configuring the first member to be cylindrical and the second member to be housed in the first member, exposure of the sliding portions of both members to the plating bath can be reduced, and alloying with zinc at the sliding portions can be prevented.

[0029] In the above, an example in which the baffle plate is fixed to the second member has been described, but the baffle plate may be fixed to the first member, which is the outer cylinder portion, and the second member may be fixed to the bath equipment.

[0030] The first member and the second member may have any shape. Specifically, the first member may be a square tube or a cylindrical tube, as long as it is cylindrical. The second member may be a solid rod shape as well as a cylindrical or square tube. The second member may have any shape as long as it can be accommodated in the first member.

[0031] 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, in order to prevent zinc adhesion and deformation due to heat. Specific examples of the stainless steel include SUS316 and SUS316L. In order to prevent deformation, it is preferable to use SUS316L that has been annealed to remove residual stress.

[0032] In addition, alloying with zinc can be prevented by applying a boron nitride-based spray to the surfaces of baffle plates and brackets.

[0033] In addition, in consideration of durability and ease of handling, the thickness of the baffle plate is preferably 2 to 6 mm.

[0034] Furthermore, the cylindrical outer tube portion 15 provided at the bottom of the above-bath equipment 13 for inserting and removing a part of the bracket 12 is preferably angled at 5 to 30° (θ1 in FIG. 6) with respect to the liquid surface of the zinc plating bath 2. More specifically, the engagement portion between the inner tube portion 16 and the outer tube 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 liquid surface of the zinc plating.

[0035] By providing a predetermined angle (θ1), when the inner cylinder 16 of the bracket 12 is inserted into the outer cylinder 15 of the above-bath equipment 13, the bracket 12 can be fixed in the plate width direction by its own weight. In addition, the diameter of the outer cylinder 15 of the above-bath equipment 13 is preferably 10 to 50 mm, taking into account the weight of the bracket 12.

[0036] In order to facilitate insertion and removal of inner cylinder portion 16 of bracket 12, it is preferable to provide an angle (θ2) of 5 to 30° at the handle portion of knob 17 of bracket 12.

[0037] 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 attaching the part of the bracket detachably to the bath equipment. Therefore, even if zinc is stuck to the baffle plate or the steel sheet and the baffle plate come into contact with each other and are deformed or damaged, it is possible to immediately eliminate the occurrence of edge overcoat, and it is possible to manufacture hot-dip galvanized steel sheets without stopping operations. Furthermore, the present invention can be applied to the manufacture of various plated steel sheets in order to address the issue of suppressing the occurrence of edge overcoat, and is not limited to the manufacture of the above-mentioned hot-dip galvanized steel sheets.

[0038] In the present invention, the above-mentioned attachment / detachment mechanism makes it possible to sequentially and precisely align the thickness of the baffle plate to the thickness of the steel plate being manufactured, thereby eliminating edge overcoat caused by the difference in thickness between the two.

[0039] [Embodiment 2] In the first embodiment, a pair of baffle plates is used, which is provided at both ends of the steel sheet in the width direction. However, when only one pair of baffle plates is used, a difference in thickness of several mm may occur between the steel sheet thickness and the baffle plate thickness depending on the size of the steel sheet to be manufactured. When such a difference in thickness occurs, turbulence occurs near the edge of the steel sheet, as shown in FIG. 8, which is one of the causes of deterioration of the edge overcoat.

[0040] In embodiment 2, a turbulence suppression device equipped with the attachment / detachment mechanism of embodiment 1 is used, and the edge overcoat is improved by using baffle plates with a thickness close to that of the steel plate depending on the thickness of the steel plate.

[0041] Regarding the material of the baffle plate, it is preferable to use SUS316L or ceramic, which is resistant to thermal deformation, so that it does not deform due to heat even if the thickness is reduced. In the case of SUS316L, it is effective to remove residual stress by additionally performing annealing treatment to prevent deformation. Conventionally, the thickness of the baffle plate has been about 3 mm to 4 mm as described above, taking deformation into consideration. However, when the baffle plate is thicker than the steel plate thickness, the baffle plate hides the steel plate, so that 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 by visual inspection. To address this issue, in the present embodiment 2, the thickness of the baffle plate is -0.5 mm to +0.1 mm relative to the thickness of the steel plate.

[0042] In the second embodiment, by using the attachment / detachment mechanism of the first embodiment, the effect of being able to replace the baffle plate immediately is utilized, and further, by making the thickness of the baffle plate closer to that of the steel plate, it is possible to suppress the generation of turbulence at the edge of the steel plate more accurately than ever before. Also, by making the thickness of the baffle plate the same as that of the plate, it becomes easier to align and check the position of the pass line of the steel plate and the baffle plate, and the workability when installing the baffle plate is improved.

[0043] The replacement of the baffle plate according to the plate thickness may be performed manually, but a controller for replacing the baffle plate may be provided to automatically replace the baffle plate by a computer. This controller may be provided inside or outside the turbulence control device.

[0044] The second embodiment can be implemented as a method for manufacturing a plated steel sheet using a baffle plate having a thickness of −0.5 mm to +0.1 mm relative to the sheet thickness of the steel sheet.

[0045] [Example 1] The baffle plate according to the first embodiment of the present invention (invention example) and a conventional baffle plate (comparison example) were each used and applied to the production of hot-dip galvanized steel sheets. In the invention example, when zinc adhered to the baffle plate, it was possible to replace it with a new baffle plate without stopping operations. This made it possible to prevent edge overcoating. On the other hand, when the conventional baffle plate (comparison example) was used, edge overcoating occurred, and operations had to be stopped and the baffle plate replaced with a new one. This resulted in a decrease in production efficiency.

[0046] [Example 2] An actual test was carried out using the second embodiment in a continuous hot-dip galvanized steel sheet manufacturing line.

[0047] In the comparative example of the present application, a 4 mm thick baffle plate was used during operation with a 2 mm thick material. In this situation, the thickness of the baffle plate was thicker than the steel plate, so when the pass line of the steel plate was checked from the side, it was hidden by the baffle plate, making it difficult to check visually. Therefore, not only were the thicknesses of the steel plate and the baffle plate not uniform, but it was also very difficult to align the position of the baffle plate in the steel plate thickness direction with the center of the pass line of the steel plate.

[0048] Due to the misalignment of the steel plate and the baffle plate, turbulence occurred at the edge of the steel plate, resulting in a greater amount of zinc deposition at the edge of the steel plate than at the center of the steel plate, resulting in a so-called edge overcoat condition.

[0049] Next, as an example of the present invention, the baffle plate was replaced with one of a thickness of 2 mm during operation of a 2 mm thick material. The pass line of the steel plate was no longer hidden by the baffle plate, and when replacing the baffle plate, it became possible to accurately align the pass line of the steel plate with the baffle plate in the thickness direction of the steel plate. In addition, by using a baffle plate with a thickness close to the thickness of the steel plate, it was possible to prevent turbulence from occurring at the edge of the steel plate, and thus to prevent excessive zinc deposition at the edge of the steel plate.

[0050] Plate thickness 2mm and target zinc coating weight 144g / m 2 Figure 9 shows the amount of zinc deposited on the edge and center of the steel sheet when a 2 mm thick baffle plate and a 4 mm thick baffle plate were used. It can be seen that when a 2 mm thick baffle plate, which has the same thickness as the steel sheet corresponding to the conditions of this invention, was used for a 2 mm thick material, the amount of zinc deposited on the edge of the steel sheet was closer to the target value than when a 4 mm thick baffle plate was used.

[0051] The present invention can be embodied as a method for producing a plated steel sheet, in which the above-mentioned turbulence suppression device is used to produce a plated steel sheet. [Explanation of symbols]

[0052] 1. Snout 2. Zinc plating bath 3. Sink Roll 4. Bath support roll 5 Wiping nozzle 6 Wiping Gas 7 Molten Zinc 8 Baffle Plate 9 Bath equipment 10 Volts 11 Baffle plate 12 Bracket 13 Bath equipment 14 Volts 15 External cylinder 16 Inner cylinder 17 Handle θ1, θ2 angle S Steel Plate

Claims

1. A baffle plate for a gas wiping device that adjusts the coating weight of a steel sheet surface by blowing gas onto the surface of the steel sheet that is immersed in a coating bath and then pulled out of the coating bath, The thickness of the baffle plate is -0.5 mm to +0.1 mm relative to the thickness of the steel plate, the baffle plate is connected to a bracket, and a portion of the bracket is removably attached to an above-bath equipment.

2. A method for producing a plated steel sheet, comprising the steps of: producing a plated steel sheet by adjusting a coating weight on a surface of the steel sheet using a gas wiping device equipped with the baffle plate according to claim 1.

3. A turbulence suppression device provided in a gas wiping device that adjusts a coating weight of a steel sheet by injecting a wiping gas from gas wiping nozzles arranged opposite to the gas wiping nozzle, A baffle plate according to claim 1; a mounting mechanism for switching the baffle plate between a mounting position in which the baffle plate is disposed between the gas wiping nozzles arranged opposite to each other and a separated position in which the baffle plate is separated from the gas wiping nozzles; A turbulence suppression device comprising:

4. The attachment / detachment mechanism includes: A first member having a cylindrical shape, and a second member having a cylindrical shape or a rod shape housed inside the first member, A baffle plate is attached to one of the first member and the second member, and the other is fixed to the bath device; The second member is accommodated inside the first member in the mounting position, 4. The turbulence suppression device according to claim 3, wherein the separated position is set in a state in which the second member is pulled out from the first member.

5. The turbulence suppression device according to claim 4, characterized in that 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.

6. A method for producing a plated steel sheet, comprising using the turbulence suppression device according to any one of claims 3 to 5.

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