JP6848996B2 - Hot metal plating equipment and plating method - Google Patents

Description

The present invention relates to a molten metal plating apparatus and a plating method.

Conventionally, in the molten metal plating process, quality defects caused by foreign matter such as dross and oxides of molten metal adhering to the surface of the steel sheet in the snout have been a problem. Against this background, a technique for suppressing foreign matter from adhering to the surface of the steel sheet in the snout has been proposed. Specifically, Patent Document 1 discloses a method of moving foreign matter on the inner bath surface of the snout with a discharge type pump and discharging the foreign matter to the outside of the snout with a suction type pump. Further, in Patent Document 2, a trough having an inner wall surface of a snout under the bath surface as one side wall is provided so that the upper edge of the other side wall of the trough is located below the bath surface, and the trough is discharged from the inside of the trough to the outside of the snout. A method of providing a mechanism for performing a trough is disclosed.

Japanese Unexamined Patent Publication No. 2003-293107 Japanese Unexamined Patent Publication No. 5-279827

However, in the method described in Patent Document 1, foreign matter may flow in the accompanying flow of the steel strip and adhere to the steel plate before the foreign matter moves to the discharge type pump. Further, in the method described in Patent Document 2, since the accompanying flow distribution in the steel strip width direction is different, foreign matter may adhere to the steel sheet in the portion where the accompanying flow is superior to the discharging ability, and the discharging ability is increased. May lead to a violent flow in the snout and cause foreign matter to be rolled up from the molten metal bath.

The present invention has been made in view of the above problems, and an object of the present invention is a molten metal plating apparatus and plating capable of inexpensively removing foreign substances in a snout and suppressing foreign substances from adhering to the surface of a steel sheet. To provide a method.

The molten metal plating apparatus according to the present invention includes a molten metal pot that houses a plating bath that is a molten metal, and a snout that is partially immersed in the plating bath and continuously penetrates the steel sheet into the plating bath. A molten metal plating apparatus comprising the above, wherein the inside of the snout is plate-shaped so as to face at least one surface of the steel plate from the opening end on the plating bath side along the length direction of the snout. The weir is arranged, and the end portion in the length direction of the weir on the side opposite to the opening end side is arranged in the vicinity of the bath surface of the plating bath.

The molten metal plating apparatus according to the present invention is characterized in that, in the above invention, the suction pump for sucking the molten metal in the region defined by the inner wall surface of the snout and the weir is provided.

In the above-mentioned invention, the molten metal plating apparatus according to the present invention is the difference between the height position of the end portion of the weir in the length direction opposite to the opening end side and the height position of the bath surface of the plating bath. Is 50 mm or less.

In the molten metal plating apparatus according to the present invention, in the above invention, the height position of the end portion in the length direction of the weir on the side opposite to the opening end side is changed along the width direction of the weir. It is characterized by.

In the above-mentioned invention, the molten metal plating apparatus according to the present invention is the difference between the height position of the end portion in the length direction of the weir on the side opposite to the opening end side and the height position of the bath surface of the plating bath. Is H1, the width of the weir is W1, and the surface area of the molten metal in the snout is A1, and the dimensional parameters (H1 and W1) / A1 satisfy the conditions shown in the following mathematical formula (1). To do.

0.005 ≦ (H1 ・ W1) / A1 ≦ 0.10. (1)

The method for plating a molten metal according to the present invention is characterized by including a step of continuously plating the molten metal on the surface of a steel sheet using the molten metal plating apparatus according to the present invention.

According to the molten metal plating apparatus and plating method according to the present invention, foreign matter in the snout can be removed at low cost to prevent foreign matter from adhering to the surface of the steel sheet.

FIG. 1 is a schematic view showing an overall configuration of a molten metal plating apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view showing the configuration of the snout shown in FIG. FIG. 3 is a schematic view showing the configuration of a modified example of the snout shown in FIG. FIG. 4 is a schematic view showing the configuration of a modified example of the snout shown in FIG. FIG. 5 is a schematic view showing the configuration of a modified example of the snout shown in FIG. FIG. 6 is a schematic view showing the configuration of a modified example of the snout shown in FIG. FIG. 7 is a diagram showing the relationship between the value of (H1 and W1) / A1 in the snout shown in FIGS. 2 and 3 and the moving speed of the foreign matter in the steel plate direction.

Hereinafter, the configuration of the molten metal plating apparatus according to the embodiment of the present invention will be described with reference to the drawings.

〔overall structure〕
First, with reference to FIG. 1, the overall configuration of the molten metal plating apparatus according to the embodiment of the present invention will be described.

FIG. 1 is a schematic view showing an overall configuration of a molten metal plating apparatus according to an embodiment of the present invention. As shown in FIG. 1, the hot-dip metal plating apparatus according to the embodiment of the present invention is a hot-dip metal pot that houses a hot-dip metal plating bath M (in the case of hot-dip galvanizing, the temperature is about 440 to 480 ° C.). 1, a snout 2 in which a part of the steel plate S is immersed in the plating bath M and continuously penetrates the steel plate S into the plating bath M, and a sink roll 3 for changing the direction of the steel plate S invading the plating bath M. Is provided as the main component. In the present embodiment, the case of hot-dip galvanizing has been illustrated, but in the present invention, the type of molten metal is not particularly limited, and it can be applied to various hot-dip metal plating. For example, zinc, aluminum, tin, lead, alloy plating thereof and the like can be exemplified.

[Snout composition]
Next, the configuration of the snout 2 shown in FIG. 1 will be described in detail with reference to FIG.

2 (a) and 2 (b) are a schematic view of a side surface and a schematic view of a plane showing the configuration of the snout 2 shown in FIG. 1, respectively. As shown in FIGS. 2A and 2B, the inner wall surface parallel to the width direction of the snout 2 is arranged substantially parallel to the width direction of the steel plate S, and the inside of the snout 2 is a plating bath of the snout 2. Plate-shaped weirs 2a and 2b are arranged so as to face the surface of the steel plate S along the length direction of the snout 2 from the opening end on the M side. Further, the widthwise ends of the weirs 2a and 2b are connected to the inner wall surface perpendicular to the width direction of the snout 2, and the lengthwise ends (weirs) of the weirs 2a and 2b opposite to the opening end side of the snout 2. The heights of 2a and 2b) are arranged near the bath surface of the plating bath M. According to such a configuration, the foreign matter D generated in the snout 2 can be held inside the weirs 2a and 2b (inside the space partitioned by the inner wall surface of the snout 2 and the weirs 2a and 2b), so that the foreign matter D can be held. Can be prevented from flowing out to the steel plate S side and adhering foreign matter D to the surface 5 of the steel plate S. Here, in FIG. 2A, the foreign matter D is shown by a large circle for easy visual understanding, but the actual foreign matter varies from a size that cannot be visually confirmed to a size that can be visually confirmed, and has various shapes. is there. The composition of the foreign matter differs depending on the type of the molten metal, but the present invention mainly aims to prevent foreign matter having a small specific gravity and easily floating on the surface of the molten metal from adhering to the steel sheet. For example, in the case of hot-dip galvanizing of the present embodiment, a small amount of aluminum is added, and an intermetallic compound called top dross, which is a combination of zinc and aluminum, is the main component. In this embodiment, two weirs are arranged, but the weir may be arranged only on the side where the foreign matter D easily flows out to the steel plate S side.

[Modification example]
Next, the configuration of the modified example of the snout 2 shown in FIG. 2 will be described with reference to FIGS. 3 to 5.

FIG. 3 is a schematic view showing the configuration of a modified example of the snout 2 shown in FIG. As shown in FIG. 3, this modified example includes suction pumps 11a and 11b for sucking molten metal inside the weirs 2a and 2b. According to such a configuration, the foreign matter D generated in the snout 2 can be continuously sucked and discharged to the outside, so that the foreign matter D can be further suppressed from adhering to the surface of the steel sheet S. In this modification, the difference (weir opening height) H1 between the heights of the weirs 2a and 2b and the height of the bath surface of the plating bath M is preferably 50 mm or less, and more preferably 30 mm or less. .. As a result, the foreign matter D generated in the snout 2 can be efficiently sucked into the weirs 2a and 2b by the suction pumps 11a and 11b. When the weir opening height H1 is 50 mm or more, when suction is performed by the suction pumps 11a and 11b, the molten metal located deeper than the molten metal near the bath surface of the plating bath M is sucked. It may be difficult to efficiently suck the foreign matter D floating on the bath surface of M. Although the suction pumps 11a and 11b are provided, the suction pumps 11a and 11b may be omitted.

FIG. 4 is a schematic view showing the configuration of a modified example of the snout 2 shown in FIG. As shown in FIG. 4, in this modification, the heights of the weirs 2a and 2b change along the width direction of the snout 2, specifically, become lower toward the center of the snout 2 in the width direction. According to such a configuration, the foreign matter D that tends to be generated at the center of the steel sheet S in the width direction can be more easily sucked, so that the foreign matter D can be further suppressed from adhering to the surface 5 of the steel sheet S. The weir opening height H1 in this case is an average value of the weir opening heights at the positions facing each other of the steel plate S. Although the suction pumps 11a and 11b are provided in this modification, the suction pumps 11a and 11b may be omitted.

5 (a) and 5 (b) are schematic views showing the configuration of a modified example of the snout 2 shown in FIG. As shown in FIGS. 5A and 5B, in this modification, the opening height H1 and width W1 of the weirs 2a and 2b and the surface area A1 of the plating bath M in the snout 2 are the following mathematical formulas (1). The conditions shown in are satisfied. According to such a configuration, the foreign matter D can be removed more efficiently and the foreign matter D can be more suppressed from adhering to the surface 5 of the steel sheet S. When the value of (H1 / W1) / A1 is larger than 0.10, the foreign matter D located deeper than the bath surface of the plating bath M is removed, so that the foreign matter floating on the bath surface M of the plating bath M is removed. The removal effect of D becomes small. On the other hand, when the value of (H1 · W1) / A1 is less than 0.005, the bath surface of the plating bath M is more likely to solidify, and the foreign matter D may not be effectively removed. Although the present modification does not include the suction pumps 11a and 11b, the suction pumps 11a and 11b may be arranged. Even if the suction pumps 11a and 11b are not arranged, if an appropriate dam is installed, foreign matter D can be suppressed from adhering to the surface of the steel plate S. However, by arranging the suction pumps 11a and 11b, the amount of foreign matter D is slightly near the steel plate S. Since the moving speed of the foreign matter D remaining in the steel plate S in the direction of the steel plate S can be reduced, it is possible to further suppress the foreign matter D from adhering to the surface of the steel plate S. The capacity of the suction pumps 11a and 11b may be selected according to the capacity inside the weir.

0.005 ≦ (H1 ・ W1) / A1 ≦ 0.10. (1)

In this embodiment, the quality defect rate of the steel plate S due to the change in the opening height H1 and width W1 of the weirs 2a and 2b shown in FIGS. 5A and 5B and the surface area A1 of the plating bath M in the snout 2. The change in was evaluated. The evaluation results are shown in Table 1 below. As shown in Table 1, when the opening height H1 of the weirs 2a and 2b is 50 mm or less, the effect of removing the foreign matter D is large and the quality defect rate of the steel plate S is small. On the other hand, when the opening height H1 of the weirs 2a and 2b is 5 mm or less, the bath surface of the plating bath M solidifies, and the foreign matter D cannot be effectively removed. Then, it was confirmed that a sufficient quality defect rate can be secured by satisfying the condition shown in the above equation (1) for the dimensional parameters of the weirs 2a and 2b.

Further, FIG. 7 shows the results of investigating the relationship between various (H1 and W1) / A1 values and the moving speed of the foreign matter D in the steel plate S direction for each capacity of the suction pump. The moving speed of the foreign matter D in the steel plate S direction was actually measured from the image. Since the effect of the suction pump changes depending on the capacity inside the weir, the value B (h ^{-1 ) obtained by dividing the capacity of the suction pump (m 3} / h) by the capacity inside the weir is shown. When the value B (h ^-1 ) is 0 (h ^-1 ), it means that the suction pump is not installed.

As shown in FIG. 7, when the suction pump is installed, the moving speed of the foreign matter D in the steel plate S direction is lower than when the suction pump is not installed, and the probability that the foreign matter D adheres to the steel plate S is high. You can see that it is getting lower. However, the higher the capacity of the suction pump, the higher the effect, but the effect is saturated, so it is not necessary to use a suction pump with a higher capacity than necessary. In this example, a sufficient effect was obtained when the value B (h ^-1 ) was 55 (h ^{-1) or less.}

Although the embodiment to which the invention made by the present inventors has been applied has been described above, the present invention is not limited by the description and the drawings which form a part of the disclosure of the present invention according to the present embodiment. For example, in the present embodiment, the weirs 2a and 2b are arranged on both surface sides of the steel plate S as shown in FIGS. 2A and 2B, but the weirs are arranged only on one surface side of the steel plate. May be good. Further, as shown in FIGS. 6A and 6B, the ends of the weirs 2a and 2b in the width direction are not connected to the inner wall surface perpendicular to the width direction of the snout 2 so as to surround the four sides of the steel plate S. Weirs 2a, 2b, 2c, and 2d may be arranged in the weir. As described above, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

1 Molten metal pot 2 Snout 2a, 2b, 2c, 2d Weir 3 Sink roll 11a, 11b Suction pump D Foreign matter M Plating bath S Steel plate

Claims (5)

A molten metal plating apparatus comprising a molten metal pot for accommodating a plating bath which is a molten metal, and a snout in which a part of the pot is immersed in the plating bath and a steel plate is continuously penetrated into the plating bath. ,
Inside the snout, a plate-shaped weir is arranged so as to face at least one surface of the steel plate from the opening end on the plating bath side along the length direction of the snout.
The end of the weir on the side opposite to the end of the opening in the length direction is arranged at a height lower than the height of the bath surface of the plating bath.
The difference between the height position of the lengthwise end of the weir on the side opposite to the opening end side and the height position of the bath surface of the plating bath is H1, the width of the weir is W1, and melting in the snout. A molten metal plating apparatus characterized in that the surface area of the metal is A1 and the dimensional parameters (H1 and W1) / A1 satisfy the conditions shown in the following mathematical formula (1).
0.005 ≦ (H1 ・ W1) / A1 ≦ 0.10 . (1) The molten metal plating apparatus according to claim 1, further comprising a suction pump for sucking molten metal in a region partitioned by the inner wall surface of the snout and the weir. Claim 1 or 2 is characterized in that the difference between the height position of the lengthwise end of the weir on the side opposite to the opening end side and the height position of the bath surface of the plating bath is 50 mm or less. The molten metal plating apparatus according to. The molten metal according to claim 1 or 2, wherein the height position of the end portion in the length direction of the weir on the side opposite to the opening end side changes along the width direction of the weir. Plating equipment. A method for plating a molten metal, which comprises a step of continuously plating the molten metal on the surface of a steel sheet using the molten metal plating apparatus according to any one of claims 1 to 4.

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