JP3580241B2 - Hot dip galvanized steel sheet manufacturing equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an apparatus for producing a hot-dip galvanized steel sheet in which a steel sheet is continuously immersed in hot-dip zinc in a hot-dip zinc bath and hot-dip galvanized.
[0002]
[Prior art]
Continuous hot-dip coating is a technique for continuously applying hot-dip metal plating to a steel sheet.Typically, the steel sheet is continuously pre-treated and kept at a high temperature in a predetermined heating pattern and then passed through a plating bath. Then, a method of cooling to normal temperature by a predetermined cooling pattern after controlling the amount of plating adhesion is adopted. FIG. 6 is a schematic sectional view of a hot-dip metal plating apparatus used in a production line of a general hot-dip metal-plated steel sheet. In this apparatus, a steel sheet S is drawn into a plating bath 22 made of a molten metal from a snout 27 kept in a non-oxidizing atmosphere, pulled up vertically through a sink roll 23 and a support roll 25, and excessively pulled by a gas wiper 24. Of molten metal is removed.
[0003]
In continuous hot-dip plating, an intermetallic compound of iron and plating components eluted from a steel sheet in a plating bath, so-called dross, is generated. Since dross contains an iron component, its density is generally higher than the density of the plating bath, and dross sediments in the plating bath.
[0004]
Since this dross is generated by the reaction between the plating component and the eluted iron, the particle size of the dross at the beginning of the generation is small, and there is no problem if it adheres to the steel sheet. If the dross becomes larger as it receives the time history and adheres to the steel sheet, it not only deteriorates the surface quality, but also impairs the smoothness of the surface during the processing of the steel sheet. It is a big problem.
[0005]
In continuous operation, such dross eventually settles at the bottom of the bath, so if the amount of deposited dross increases, the dross once settled again due to the flow of molten zinc induced by the passing of the steel sheet. And the presence of the re-emerged dross is the most undesirable in terms of product quality.
[0006]
To prevent the dross from being rolled up, Japanese Patent Application Laid-Open No. 5-171388 proposes a special bath which removes dross by circulating a plating bath in a hot-dip zinc bath through a filtration device (prior art). 1). Further, in Japanese Patent Application Laid-Open No. 4-154948, a pump is used for a hot-dip zinc bath and a precipitation bath connected to a plating bath through a shallow flow path. There has been proposed a method of preventing sedimentation and deposition of dross in a plating bath, and actively depositing and sedimenting generated dross in the sedimentation bath, and returning the plating bath from which dross can be separated to a bathtub by a pump (prior art). 2). Further, in Japanese Patent Application Laid-Open No. 7-207419, a static stabilizing tank and a suction pump are installed in a galvanizing bath, an inclined plate having an inclined upper surface is provided below the sink roll, and a suction pump is provided below the inclined plate. A method has been proposed in which the suction port of the nozzle is communicated with a static stabilization tank (prior art 3). Further, in JP-A-7-268578, as shown in FIG. 7, a settling tank 33 for settling and depositing dross is provided outside a plating tank 31 having a bottom having an arc-shaped curve. By the flow formed by running the steel sheet S, the molten zinc containing the dross in the plating tank 31 is guided to the sedimentation tank 33 from the flow path provided on the exit side of the plating tank 31, while the molten zinc in the precipitation tank 33 A method has been proposed in which molten zinc, which has been cleaned by sedimentation of the dross, is returned into the plating tank 31 from a communication hole 35 provided on the entrance side of the plating tank 31 (prior art 4).
[0007]
However, there are many problems with these techniques. Specifically, in the case of the filtration type as in the prior art 1, the size of the dross that can be removed by filtration changes over time and is not stable, and the dross removed by filtration is removed from the filtration device. However, there is a problem in that the filtration device must be stopped, and during that time, filtration cannot be performed. When a precipitation bath and a pump connected to the plating bath via a flow path are used as in the prior art 2, an apparatus for heating and maintaining the precipitation bath in addition to the conventional apparatus for heating and maintaining the plating bath. It is necessary to separately control the device, and it is difficult to use the pump in molten zinc for a long time due to the problem of corrosion resistance, and it takes time to maintain the pump. There's a problem.
[0008]
Furthermore, in the prior art 3, in addition to the problem associated with using the same pump as in the prior art 2, the only dross that can be collected in the static stabilization tank is the dross that has settled below the sink rolls. When the speed is increased or the width of the steel strip is increased, there is a high risk that dross that has been wound up without settling stably in the plating tank will adhere to the steel strip surface and cause surface defects. There's a problem.
[0009]
Furthermore, in the prior art 4, although a filtering device and a pump were not used, the molten zinc in the plating tank 31 was not sufficiently stirred, and there was a difference in the inflow plate temperature and the aluminum concentration in the plating bath on the front and back of the steel plate S. There is a problem that dross generated on the sink roll side of the steel sheet S is difficult to be discharged out of the plating tank 31 and the quality improvement effect is limited. Furthermore, it is impossible to completely prevent the dross from being hoisted even if a member for interrupting the flow is simply provided between the sink roll and the settled dross as in this technique.
[0010]
In any case, in these conventional techniques, the dross existing on the front and back of the steel sheet cannot be appropriately separated without using a driving device such as a pump, so that the ability to reduce the dross is limited. It is difficult to drastically reduce dross.
[0011]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and it is possible to appropriately separate dross from molten zinc without using a filtering device or a pump, etc., the ability to separate dross is extremely high, and quality defects are extremely high. An object of the present invention is to provide an apparatus for manufacturing a hot-dip galvanized steel sheet that can manufacture a small amount of high-quality hot-dip galvanized steel sheet.
[0012]
[Means for Solving the Problems]
The present inventors investigated the flow of hot-dip galvanizing in a hot-dip galvanizing tank (plating pot) used for normal operations, the mechanism of dross generation, and the behavior of dross in the plating pot. As a result, the following was confirmed.
[0013]
That is, as shown in FIGS. 1A, 1B and 1C, the driving force of the flow of the molten zinc in the plating pot is as follows.
1. (A) Associated flow of molten zinc generated by a strip running in a plating pot indicated by symbol A in FIG.
2. (B) a discharge flow in which the accompanying flow having no place to go at the contact portion of the strip and the sink roll as indicated by the symbol B in the sink roll body length direction.
3. (C) Flow by electromagnetic force in an induction heating device for keeping or heating molten zinc indicated by symbol C in FIG.
4. (A) This is a flow due to natural convection due to uneven temperature of molten zinc generated near an ingot inlet for supplying solid phase zinc indicated by symbol D, of which the flows of symbols A, B and C are particularly important. That is.
[0014]
The reason why the dross is intensively deposited from the lower portion near the sink roll to the end of the plating pot is that the dross is wound up again by the flow of the symbol A shown in FIG. It was found from the data of the water model test that the dross was rolled up or blown up at the bottom, and the flow of the symbol C caused the calmed dross to roll up.
[0015]
In addition, when the strip enters the plating pot, a reaction occurs in which iron powder adhering to the strip and iron eluted by reacting the strip with molten zinc generate an intermetallic compound with zinc. This intermetallic compound is fine dross, and this fine dross flows along with the running of the strip, once reaches the bottom of the hot-dip galvanizing pot, and mixes with the low-temperature plating bath at the bottom, and , Due to the solubility of iron in molten zinc.
[0016]
Furthermore, according to the analysis so far, the size of the dross in question is 100 μm or more when converted into a sphere, and when the density of the dross of about 100 μm is analyzed, the density of the dross in the molten zinc bath at 460 ° C. 6860kg / m³Met. From this, it was found that, when converted into a spherical shape, the dross that caused a problem settle at a speed of about 1 m per hour if a stationary state is formed.
[0017]
From the above, in order to properly perform dross separation from hot-dip zinc, and to produce high-quality hot-dip galvanized steel sheet with extremely few quality defects, a small container for accommodating sink rolls is provided. The molten zinc is vigorously agitated in the plating area to discharge dross with a large particle size, which is problematic, and the dross once flowing out of the small container is settled and separated as much as possible outside the plating section, and only the supernatant bath is returned to the plating section. In addition, it has been found that it is effective to provide a mechanism for controlling the flow of molten zinc discharged from the small container and to promote the separation of dross outside the plating section. Also, particularly at the time of high-speed sheet passing, the above-mentioned symbol A sometimes descends after reaching the plating pot bath wall to wind up the deposited dross, but guides the molten zinc flow discharged from the small container downward. In addition, it has been found that by controlling the molten zinc flow so that dross does not roll up at the bottom of the plating pot, dross rolling up can be prevented even during high-speed sheet passing.
[0018]
The present invention has been made based on the above findings, and the first invention is a method of continuously immersing a steel sheet to be plated in hot-dip zinc to form a plating layer by adhering hot-dip zinc to the surface thereof. An apparatus for manufacturing a galvanized steel sheet,
A molten zinc container for storing the molten zinc,
Sink roll is provided so as to be immersed in the molten zinc in the molten zinc container, around which the steel plate to be plated is wound,
A small container provided to accommodate the sink roll, the upper part of which is opened,
A rectifying mechanism that controls the flow of molten zinc from within the small container and promotes the separation of dross from the molten zinc;And
The rectifying mechanism has a first rectifying plate that extends from the inside of the small container to the bottom of the molten zinc container and extends from the inside of the small container to the bottom of the molten zinc container.A manufacturing apparatus for a hot-dip galvanized steel sheet is provided.
[0019]
The second invention is based on the first invention,The rectifying mechanism further includes a second rectifying plate provided at a bottom portion of the molten zinc container and configured to reduce a flow rate of the molten zinc flowing through the bottom portion of the molten zinc container.An apparatus for producing a hot-dip galvanized steel sheet is provided.
[0021]
No.3The invention is the first inventionOr the second inventionIn the first aspect, the rectifying mechanism is provided at a side portion and / or a rear portion of the gap between the molten zinc container and the small container in the passing plate direction, and reduces a flow rate of the molten zinc flowing vertically through the portion. 3. An apparatus for manufacturing a hot-dip galvanized steel sheet, further comprising: a third rectifying plate.
[0022]
No.4The invention is a second inventionOr the third invention, The second rectifying plate and / or the third rectifying plate reduces the flow of molten zinc to 2 cm / min or less, and provides a manufacturing apparatus for a galvanized steel sheet.
[0023]
No.5The invention is based on the first invention4In any one of the inventions, in the small container, the upper end of the rear part in the passing direction is 200 mm or less from the bath surface of the molten zinc, and the upper end of the front part in the passing direction is 200 mm or more and 500 mm from the bath surface of the molten zinc. A manufacturing apparatus for a hot-dip galvanized steel sheet, characterized in that the depth of the hot-dip galvanized steel sheet is 200 mm or more and 800 mm or less from the bath surface of the hot-dip zinc.
[0024]
No.6The invention is based on the first invention5In any one of the inventions, the small container is separated from the sink roll, the member supporting the sink roll, and the steel plate to be plated in a range of 100 mm or more and 500 mm or less, producing a hot-dip galvanized steel sheet. Provide equipment.
[0025]
No.7The invention is based on the first invention6In any one of the inventions, there is provided an apparatus for manufacturing a hot-dip galvanized steel sheet, wherein an inner surface of the small container has a curved surface at a corner.
[0026]
ADVANTAGE OF THE INVENTION According to this invention, the small container provided so that a sink roll may be accommodated, and the upper part was opened, and the rectification which controls the flow of molten zinc from this small container, and promotes the separation of dross from molten zinc. A mechanism is provided, so that dross that causes a problem is eliminated while vigorously stirring the plating part, dross outside the plating part is separated as much as possible, and dross that causes a problem is not returned to the plating part. Can be. Then, as the rectifying mechanism, as in the first invention, the rectifying mechanism is formed so as to extend forward of the upper end of the small container in the passing plate direction and form a molten zinc flow that guides dross from inside the small container to the bottom of the molten zinc container. By having one current plate, dross generated in the small container can be quickly separated from the molten zinc. Therefore, surface defects due to dross are reduced, and a very high quality hot-dip galvanized steel sheet can be manufactured.
[0027]
Further, according to the second invention, in the first invention, the rectifying mechanism is provided at the bottom of the molten zinc container, and further includes a second rectifying plate configured to reduce the flow of the molten zinc flowing through the bottom of the molten zinc container. The dross deposited on the bottom of the molten zinc container can be prevented from being rolled up. In addition,3According to the invention, the rectifying mechanism is provided at a side portion or / and a rear portion of the gap between the molten zinc container and the small container in the passing plate direction, and controls the molten zinc flow flowing through the portion in the vertical direction. With the third current plate that decelerates, dross is prevented from flowing upward from the bottom of the molten zinc container and entering the small container.
[0028]
From the first invention to the second3With any of the current plates of the invention, the molten zinc flow can be properly controlled to promote dross separation, but in particular,Like the second inventionBy providing the first current plate and the second current plate, dross can be quickly guided to the bottom of the molten zinc container and separated, and the bottom of the molten zinc container on which dross is deposited is provided. Since the flow of molten zinc flowing through the steel sheet can be reduced, the dross winding can be extremely effectively prevented even during high-speed sheet passing where the accompanying flow of the steel sheet increases. In addition, this combination3By combining the third straightening vane of the invention, the danger of dross winding during high-speed passing can be further reduced.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 2 is a top view showing an example of the apparatus for manufacturing a hot-dip galvanized steel sheet according to the embodiment of the present invention, FIG. 3 is a sectional view taken along the line AA in FIG. 2, and FIG. 4 is a line BB in FIG. FIG. 5 is a cross-sectional arrow view of FIG. 2.
This apparatus for manufacturing a hot-dip galvanized steel sheet has a plating pot 10 for storing hot-dip zinc 2, and an induction heater 6 for heating and keeping the hot-dip zinc on both sides of the hot-dip zinc pot 10. Have been. Further, a small pot 8 as a small container is provided in the plating pot 10 so as to be immersed in the molten zinc. Above the small pot 8, a snout 7 whose inside is kept in a non-oxidizing atmosphere is arranged so that the end is immersed in the molten zinc in the small pot 8. The steel sheet S is continuously supplied into the molten zinc. Below the bath surface in the small pot 8, a sink roll 3 for turning the traveling direction of the steel sheet S upward and a pair of support rolls 5 for supporting the movement of the steel sheet S are supported by the jig 4, respectively. , So as to be immersed in the molten zinc in the small pot 8. In the vicinity of the bath surface of the molten zinc 2 at the end of the plating pot 10, a zinc ingot 9 for replenishing the molten zinc is immersed.
[0030]
The small pot 8 has a shape which is bent at a predetermined curvature so as to be along the passing direction of the steel plate S, a bottom plate 8a provided so as to cover the sink roll 3 and the support roll 5, and both sides of the bottom plate 8a. Each side plate 8b is provided with a side plate 8b provided so as to cover an end of the sink roll 3, and an upper portion of the small pot 8 is opened. A first rectifying plate 11 that forms a flow of molten zinc that guides dross in the small pot 8 to the bottom of the plating pot 10 extends in front of the bottom plate 8a in the sheet passing direction. The small pot 8 is provided so as to be entirely immersed in the molten zinc. However, the upper end of the bottom plate 8a at the rear in the passing direction is provided higher than the upper end of the bottom plate 8a at the front in the passing direction. The upper end is provided so as to be higher than the upper end of the sink roll 3 and lower than the upper and lower ends of the bottom plate 8a in the front and rear directions in the passing direction. Further, since the corners of the inner surface of the small pot 8 are curved as shown in FIG. 4, the molten metal in the small pot 8 is sufficiently stirred without stagnation at the corners.
[0031]
A plurality of second rectifying plates 12 are provided on the bottom surface of the bottom plate 8a of the small pot 8 and on the bottom surface of the plating pot 10, respectively. In this apparatus for manufacturing a hot-dip galvanized steel sheet, hot zinc flows through the bottom of the hot pot 10 as shown by the white arrow in FIG. 3. The flow of molten zinc through the bottom of 10 is slowed down.
[0032]
In addition, a plurality of third rectifying plates 13 are provided on the outer wall of the small pot 8 and the inner wall of the plating pot 10 at the side portion and the rear portion in the passing direction. By providing the third current plate 13 in this way, the vertical flow of the molten zinc is reduced at the side portion and the rear portion in the passing direction of the gap between the small pot 8 and the plating pot 10.
[0033]
An opening 8c is provided at a position corresponding to the bottom of the small pot 8 of the bottom plate 8a, and a cylindrical foot 20 having a hollow portion 20a communicating with the opening 8c is provided. Is supported. Since the hollow portion 20a of the foot portion 20 communicates with the opening 8c of the bottom plate 8a, when the small pot 8 is submerged in the molten zinc 2, the molten zinc 2 flows into the small pot 8 through the foot portion 20. Work can be done easily. When the small pot 8 is pulled up from the molten zinc 2, the work is simple because the molten zinc 2 in the small pot 8 is discharged through the inside of the foot 20. When the small pot 8 is submerged in the molten zinc 2, the bottom of the foot 20 is grounded to the bottom of the plating pot 10, so that the molten zinc 2 inside and outside the small pot 8 is hollow in the foot 20 during operation. There is no mixing through the part 20a.
[0034]
In the apparatus for manufacturing a hot-dip galvanized steel sheet configured as described above, the steel sheet S is continuously immersed from the snout 7 into the hot-dip zinc 2 stored in the plating pot 10. Then, after the steel sheet S is turned upward by the sink roll 3, the steel sheet S is passed above the plating pot 10 through the space between the support rolls 5, and excess molten zinc is removed by a gas wiper (not shown). A system-plated steel sheet is obtained.
[0035]
At this time, when the steel sheet S is passed through, a sink flow of the sink roll 3 and the steel sheet S is generated. Since the tail flow is formed inside the small pot 8, the bottom of the plating pot 10 is affected by the tail flow. Is prevented from being directly received. Since the side of the sink roll 3 is covered with the side wall 8b of the small pot 8, the flow of the molten zinc flowing in the body length direction of the sink roll 3 from the contact portion between the steel sheet S and the sink roll 3 is this. It collides with the side wall 8b, and is divided into a downward flow and an upward flow flowing toward the bottom of the small pot 8. Due to this descending flow, the molten zinc in the small pot 8 is vigorously stirred, so that dross does not accumulate on the bottom of the small pot 8. On the other hand, the ascending flow does not become a driving force for winding up the dross deposited on the bottom of the plating pot 10, and is mixed with the molten zinc flowing into the small pot 8 to make the temperature uniform and the molten zinc uniform. It is used effectively to promote the conversion. In this way, the molten zinc in the small pot 8 is vigorously stirred, and the molten zinc containing dross is discharged from the small pot 8 by the accompanying flow.
[0036]
The molten zinc flow discharged from the small pot 8 is guided to the first straightening plate 11 extending from the upper portion of the small pot 8 in the passing direction at the upper end thereof, reaches the wall surface of the plating pot 10 and then toward the bottom. The dross in the small pot 8 is quickly guided to the bottom of the plating pot 10 by this flow, and the dross in question is settled and separated there. At this time, in addition to the fact that the vicinity of the sink roll 3 where the entrained flow is formed and the bottom of the plating pot 10 are cut off by the small pot 8, the molten zinc flow flowing through the bottom of the plating pot 10 is the second flow. Since the speed is reduced by the current plate 12, the molten zinc is almost in a stationary state at the bottom of the plating pot 10, whereby the dross is settled and separated with an extremely high separation ability due to the density difference from the molten zinc. 10 is deposited at the bottom. Further, it is possible to prevent the dross once deposited from being rolled up. This effect is particularly effective at the time of high-speed sheet passing where the accompanying flow of the steel sheet increases.
[0037]
The molten zinc from which dross has been separated at the bottom of the plating pot 10 is circulated by flowing a clean supernatant portion into the small pot 8 from the side and the rear of the plating bath in the direction of the plate passing. Used for the production of galvanized steel sheets. At this time, since the molten zinc flow flowing from the bottom of the plating pot 10 to the upper side of the plating bath is decelerated by the third straightening vane, dross having a problematic size is caused to flow from the bottom of the plating pot 10 to the upper side of the plating bath. Thus, mixing in the small pot 8 is prevented. As described above, the third rectifying plate 13 has a function of separating the inside of the small pot 8 as a plating unit for plating and the bottom of the plating pot 10 as a settling unit for settling and separating dross. This is particularly effective at the time of high-speed sheet passing where the accompanying flow of the steel sheet increases. The third current plate 13 may be provided separately on the rear side and on both sides in the passing direction.
[0038]
More specifically, the second current plate 12 preferably reduces the flow rate of the molten zinc to 2 cm / min or less. By making the flow rate of the molten zinc flow smaller than the dross sedimentation velocity, which is a problem, it is possible to more reliably prevent the occurrence of surface defects caused by the winding up of the dross deposited on the bottom of the plating pot 10. . Further, it is preferable that the third current plate 13 also reduces the flow rate of the molten zinc to 2 cm / min or less. By doing so, it is possible to more reliably prevent the occurrence of surface defects due to dross, which is a problem, entering the plating portion from the bottom of the plating pot 10.
[0039]
As described above, in the present embodiment, the rectifying mechanism includes the first rectifying plate 11, the second rectifying plate 12, and the third rectifying plate 13, which control the flow of the molten zinc. However, these current plates may be used alone or in any combination. Further, the shape of the current plate is not limited to the illustrated one, and may be any shape having the above-described function. Further, the straightening mechanism in the present invention may be any mechanism that controls the flow of molten zinc from inside the small pot 8 and promotes the separation of dross from the molten zinc, and is limited to one having such a straightening plate. Not something.
[0040]
In order to sufficiently stir the molten zinc in the small pot 8, it is desirable that the small pot 8 is separated from the sink roll 3, the jig 4 and the steel sheet S within a range of 100 mm or more and 500 mm or less. The reason why the length is set to 100 mm or more is that the small pot 8 must be installed before inserting the in-bath equipment such as the sink roll 3, so that a margin necessary for installation is secured, and the local temperature distribution This is to prevent the occurrence of a bias in the concentration distribution. The reason for setting the length to 500 mm or less is that it becomes difficult to form a strong flow for stirring the bottom of the small pot 8 above this distance.
[0041]
It is preferable that the rear end (snout 7 side) of the bottom plate 8a of the small pot 8 has an upper end higher than the snout 7 lower end and a depth of 200 mm or less from the molten zinc 2 bath surface. Further, it is preferable that the upper end of the front part in the passing direction of the bottom plate 8a has a depth of 200 mm or more and 500 mm or less from the bath surface of the molten zinc 2. If the upper end of the bottom plate 8a in the forward direction of the bottom plate 8a is less than 200 mm from the bath surface of the molten zinc 2, the molten zinc cannot be discharged and circulated from the small pot 8 smoothly, and if it exceeds 500 mm from the bath surface, The amount of molten zinc discharged from the small pot 8 becomes too large, and it is impossible to secure a sufficient time for the dross to settle out of the small pot 8. Further, the upper end of the side plate 8b of the small pot 8 preferably has a depth of 200 mm or more and 800 mm or less from the bath surface. If the upper end of the side plate 8b is less than 200 mm from the bath surface, circulation return cannot be sufficiently obtained, and if it exceeds 800 mm, the amount of molten zinc flowing into the small pot 8 becomes too large, and Not enough time to settle.
[0042]
Next, results of an experiment performed using the apparatus for manufacturing a hot-dip galvanized steel sheet according to the present invention will be described. Depth L of the upper end on the steel sheet entry side in FIG.₁= 100mm, depth L at the upper end of the steel sheet exit side₂= 300 mm, depth L at the upper end of the side wall 8b₃An experiment was conducted in which a small pot 8 having a size of = 700 mm was arranged, the first rectifying plate 11, the second rectifying plate 12, and the third rectifying plate 13 were provided as described above, and a plated steel sheet was manufactured. As a result, it was confirmed that a high-quality hot-dip galvanized steel sheet with extremely few quality defects could be manufactured even when the sheet passing speed of the steel sheet S was increased from 100 m / min to 150 m / min.
[0043]
【The invention's effect】
As described above, according to the present invention, in the molten zinc stored in the molten zinc container, a small container accommodating the sink roll and a rectifying mechanism that controls the flow of the molten zinc to promote the separation of the dross are provided. Since the provided dross is eliminated while vigorously stirring the plating part, dross outside the plating part is separated as much as possible, and the dross causing the problem can be prevented from returning to the plating part. High quality hot-dip galvanized steel sheet with very few quality defects can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the flow of molten zinc in a plating pot.
FIG. 2 is a top view showing an example of an apparatus for manufacturing a hot-dip galvanized steel sheet according to an embodiment of the present invention.
FIG. 3 is a view taken along the line AA in FIG. 2;
FIG. 4 is a view taken in the direction of arrows BB in FIG. 2;
FIG. 5 is a view taken in the direction of arrows CC in FIG. 2;
FIG. 6 is a schematic sectional view of a conventional general hot-dip metal plating apparatus.
FIG. 7 is a schematic sectional view of a hot-dip metal plating apparatus described in JP-A-7-268578.
[Explanation of symbols]
S; steel plate
2: molten zinc
3; sink roll
4: Jig
5; Support roll
6; induction heater
7; Snout
8; small pot (small container)
9; zinc ingot
10; Plating pot (hot-dip zinc container)
11; first current plate
12: second straightening vane
13: Third straightening plate
20; foot

Claims (7)

A manufacturing apparatus for a hot-dip galvanized steel sheet in which a steel sheet to be plated is continuously immersed in hot-dip zinc and a hot-dip zinc is adhered to the surface to form a coating layer,
A molten zinc container for storing the molten zinc,
Sink roll is provided so as to be immersed in the molten zinc in the molten zinc container, around which the steel plate to be plated is wound,
A small container provided to accommodate the sink roll, the upper part of which is opened,
A rectifying mechanism that controls the flow of molten zinc from within the small container and promotes the separation of dross from the molten zinc,
The rectifying mechanism may include a first rectifying plate that extends from the upper end of the small container to a front portion in the passing plate direction and that forms a molten zinc flow that guides dross from the inside of the small container to the bottom of the molten zinc container. A manufacturing device for hot-dip galvanized steel sheets. 2. The melting device according to claim 1, wherein the rectifying mechanism further includes a second rectifying plate provided at a bottom of the molten zinc container and configured to reduce a flow of the molten zinc flowing through the bottom of the molten zinc container. 3. Manufacturing equipment for galvanized steel sheets. The rectifying mechanism is provided at a side portion and / or a rear portion of the gap between the molten zinc container and the small container in the passing plate direction, and reduces a molten zinc flow flowing through the portion in a vertical direction. The apparatus for manufacturing a hot-dip galvanized steel sheet according to claim 1 or 2 , further comprising a current plate. The second rectifying plate or / and the third rectifying plate is manufactured of galvanized steel sheet according to claim 2 or claim 3, characterized in that to decelerate the molten zinc flow below 2 cm / min apparatus. In the small container, the upper end of the rear part in the passing direction has a depth of 200 mm or less from the bath surface of the molten zinc, and the upper end of the front part in the passing direction has a depth of 200 mm or more and 500 mm or less from the bath surface of the molten zinc. The hot-dip galvanized steel sheet according to any one of claims 1 to 4 , wherein the upper end of the side part in the sheet passing direction has a depth of 200 mm or more and 800 mm or less from the bath surface of the molten zinc. Manufacturing equipment. The small container according to any one of claims 1 to 5 , wherein the small container is separated from the member supporting the sink roll and the steel plate to be plated in a range of 100 mm or more and 500 mm or less. An apparatus for manufacturing a hot-dip galvanized steel sheet according to the above. The apparatus for manufacturing a hot-dip galvanized steel sheet according to any one of claims 1 to 6 , wherein an inner surface of the small container has a curved surface at a corner thereof.

Images