JP7667438B2 - Wiping nozzle clogging prevention device and wiping nozzle clogging prevention method - Google Patents

Description

The present invention relates to a wiping nozzle clogging prevention device that prevents clogging of a wiping nozzle that adjusts the coating weight of a steel sheet in hot-dip metal coating equipment, and a method for preventing clogging of the wiping nozzle.

For example, hot-dip galvanized steel sheets in which the surface of a steel sheet is subjected to hot-dip galvanization, and galvannealed steel sheets in which the same is alloyed, have excellent corrosion resistance and are therefore widely used in a variety of applications, such as home appliances, building materials, civil engineering, machinery, automobiles, furniture, and containers.
Such hot-dip galvanized steel sheets are manufactured, for example, by hot-dip galvanizing equipment including a hot-dip galvanizing bath and a wiping nozzle that sprays a wiping gas onto the steel sheet that has passed through the hot-dip galvanizing bath to adjust the coating weight. The wiping nozzle is configured to spray the wiping gas onto the entire width of the steel sheet.

Here, in the case where the above-mentioned wiping nozzle becomes clogged in part of the width direction, the wiping gas is not sprayed uniformly in the width direction, and the coating weight varies in part of the width direction of the steel sheet, which may result in streaky appearance defects in the hot-dip galvanized steel sheet.
Clogging of the wiping nozzle occurs when zinc adhering to the steel sheet is scattered by the wiping gas, and is more likely to occur when the discharge pressure of the wiping gas is high. For this reason, clogging tends to occur more frequently when the coating weight on the steel sheet is low or when the steel sheet travels at a high speed.

Furthermore, at the widthwise ends of the steel sheet, the wiping gases from the wiping nozzles arranged opposite each other collide with each other, causing the gas flow to become turbulent, which causes zinc to scatter and easily causes the wiping nozzles to become clogged.
Therefore, Patent Document 1 proposes a method of preventing zinc from scattering at the width direction ends of a traveling steel sheet by injecting a purge gas.

Furthermore, in the above-mentioned hot-dip galvanizing equipment, a preceding steel sheet and a following steel sheet are welded together so that a plurality of steel sheets pass through the hot-dip galvanizing bath in succession. Here, when the preceding steel sheet and the following steel sheet have different widths, a step occurs in the welded portion in the width direction, and zinc adhering to the step may scatter and cause clogging of the wiping nozzle.
Therefore, Patent Document 2 proposes a method of spraying high-pressure gas diagonally downward toward the widthwise end of a traveling steel plate to remove zinc that has adhered to the steps and suppress clogging of the wiping nozzle.

Japanese Patent Application Publication No. 07-331404 JP 2015-004115 A

When welding a preceding steel sheet and a following steel sheet, a punch hole may be formed in the welded portion or in the vicinity of the welded portion in order to identify the running position of the welded portion.
Recently, there has been a demand for further improvement in surface quality in the above-mentioned hot-dip galvanized steel sheets and the like, and it is necessary to further suppress the occurrence of poor appearance due to clogging of the wiping nozzle.
Therefore, the visual inspection of hot-dip galvanized steel sheets was conducted under stricter standards than before, and it was found that visual defects occurred at the width positions where punch holes were formed when the welds passed through. It was also found that this visual defect was likely to occur on one side of the steel sheet.

The above-mentioned punched holes are formed by punching from one side of the steel sheet, and a "burr" may be formed on the other side of the steel sheet during punching. When the punched holes pass through a hot-dip metal coating bath, excess molten metal tends to adhere to the burr of the punched holes. For this reason, clogging of the wiping nozzle occurs on the side where the burr is formed, which may cause the above-mentioned poor appearance.
Therefore, in order to further improve the surface quality of the above-mentioned hot-dip galvanized steel sheet and the like, it is necessary to suppress clogging of the wiping nozzle caused by punch holes.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a wiping nozzle clogging prevention device and a wiping nozzle clogging prevention method that can prevent clogging of the wiping nozzle by removing excess molten metal adhering to the punch hole even when the punch hole formed at or near the welded part passes between the wiping nozzles, thereby suppressing the occurrence of poor appearance due to clogging of the wiping nozzle and producing high-quality hot-dip metal-plated steel sheet.

In order to solve the above problems, the present invention provides a wiping nozzle clogging prevention device for preventing clogging in a hot-dip metal coating facility in which a plurality of steel sheets, each formed by welding a preceding steel sheet and a following steel sheet, are successively passed through a hot-dip metal coating bath, and a wiping gas is sprayed from wiping nozzles respectively disposed on one side and the other side of the steel sheets toward the steel sheets that have passed through the hot-dip metal coating bath to adjust the coating weight of the steel sheets. The wiping nozzle clogging prevention device prevents clogging of the wiping nozzle, and the wiping nozzle is provided with a punch hole at or near the weld between the preceding steel sheet and the following steel sheet, and the weld between the preceding steel sheet and the following steel sheet is removed from the hot-dip metal coating bath. The method comprises: a removal gas injection means for injecting a removal gas to remove molten zinc adhering to a punch hole, toward the position where the steel sheet passes between the wiping nozzles; and a control unit for instructing the removal gas injection means to inject removal gas from the molten metal plating bath toward the punch hole passing between the wiping nozzles, based on position information of the punch hole obtained by utilizing the punch hole formed at the welded portion or in the vicinity of the welded portion between the preceding steel sheet and the following steel sheet, and the removal gas injection means is disposed at least on the side of the steel sheet where the burr portion of the punch hole is formed .

According to the wiping nozzle clogging prevention device of this configuration, the control unit is configured to instruct the removal gas injection means to inject removal gas from the molten metal plating bath toward the punch hole passing between the wiping nozzles based on the position information of the punch hole obtained by using the punch hole formed at or near the welded portion between the preceding steel sheet and the following steel sheet. Therefore, when the punch hole passes between the wiping nozzles, the molten metal adhering to the punch hole can be removed by the removal gas, and clogging of the wiping nozzle can be prevented. This makes it possible to suppress the occurrence of poor appearance due to clogging of the wiping nozzle.

In the wiping nozzle clogging prevention device of the present invention, the removal gas ejection means is preferably disposed at a position farther away from the surface of the molten metal plating bath than the wiping nozzle.
In this case, it becomes possible to position the wiping nozzle close to the bath surface of the molten metal plating bath, and even if the molten metal plating bath contains elements that are easily oxidized, it becomes possible to accurately adjust the coating weight by the wiping nozzle before the molten metal adhering to the steel sheet oxidizes.

Furthermore, the wiping-nozzle clogging prevention device of the present invention may be configured so that the ejection angle of the removal gas is adjustable.
In this case, the molten metal adhering to the punched holes can be blown off in a desired direction, and clogging of the wiping nozzle can be reliably prevented.

The method for preventing clogging of a wiping nozzle of the present invention is a method for preventing clogging of a wiping nozzle in a hot-dip metal coating facility in which a plurality of steel sheets, each formed by welding a preceding steel sheet and a following steel sheet, are continuously supplied to a hot-dip metal coating bath, and a wiping gas is sprayed from wiping nozzles respectively arranged on one side and the other side of the steel sheet toward the steel sheet that has passed through the hot-dip metal coating bath to adjust the coating adhesion weight of the steel sheet, characterized in that a punch hole is formed at or near the welded portion between the preceding steel sheet and the following steel sheet, and when the punch hole passes from the hot-dip metal coating bath between the wiping nozzles, a removal gas is sprayed toward the punch hole by a removal gas spraying means arranged at least on the side of the steel sheet on which the burr portion of the punch hole is formed, to remove molten metal adhering to the punch hole.

According to this method for preventing clogging of the wiping nozzle, a punch hole is formed at or near the welded portion between the preceding steel sheet and the following steel sheet, and when the punch hole passes between the wiping nozzle and the molten metal plating bath, a removal gas is sprayed toward the punch hole to remove the molten metal adhering to the punch hole, thereby making it possible to prevent clogging of the wiping nozzle. This makes it possible to suppress the occurrence of poor appearance due to clogging of the wiping nozzle.

As described above, according to the present invention, it is possible to provide a wiping nozzle clogging prevention device and a wiping nozzle clogging prevention method that can prevent clogging of the wiping nozzle by removing molten metal adhering to the punch hole even when the punch hole formed at or near the weld passes between the wiping nozzles, suppress the occurrence of appearance defects caused by clogging of the wiping nozzle, and produce high-quality hot-dip metal-plated steel sheet.

FIG. 1 is a schematic explanatory diagram showing a hot-dip metal plating facility. FIG. 4 is an enlarged explanatory view of the periphery of a wiping nozzle. 1 is a schematic explanatory diagram of a wiping nozzle clogging prevention device according to an embodiment of the present invention; 1 is a schematic explanatory diagram of a wiping nozzle clogging prevention device according to an embodiment of the present invention; FIG. 11 is a schematic explanatory diagram of a wiping nozzle clogging prevention device according to another embodiment of the present invention. 1 is a graph showing the results of an example.

Below, a wiping nozzle clogging prevention device and a wiping nozzle clogging prevention method according to one embodiment of the present invention will be described with reference to the attached drawings. Note that the present invention is not limited to the following embodiment.

First, the hot-dip metal plating equipment 10 equipped with a wiping nozzle clogging prevention device according to this embodiment will be described. The hot-dip metal plating equipment 10 in this embodiment is a hot-dip galvanizing equipment that forms a hot-dip galvanizing layer or a Zn-Al alloy plating layer on the surface of a steel sheet S.

FIG. 1 shows a hot-dip metal coating facility 10 equipped with a wiping nozzle clogging prevention device according to this embodiment.
This hot-dip metal coating equipment 10 includes a coating tank 11 in which molten zinc M constituting a coating bath is stored, a sink roll 12 immersed in this coating tank 11, a first support roll 13 and a second support roll 14 for guiding a steel sheet S traveling in the coating bath, and a steel sheet supplying device 15 for continuously introducing the steel sheet S into the coating bath. The steel sheet supplying device 15 includes a cooling section 16 for cooling the steel strip S that has passed through an annealing furnace (not shown).

The hot dip metal coating equipment 10 of this embodiment is provided with a wiping nozzle 18 that sprays wiping gas toward the steel sheet S that has passed through the coating bath to adjust the coating weight of the steel sheet S.
1, the wiping nozzles 18 are disposed on one surface side and the other surface side of the steel sheet S so as to sandwich the traveling steel sheet S in the thickness direction. Moreover, the wiping nozzles 18 are configured so as to be able to spray wiping gas over the entire width of the steel sheet S.

Here, the hot dip metal coating equipment 10 of this embodiment is configured such that a plurality of steel sheets S are passed through the coating bath in succession by welding the preceding steel sheet S1 and the following steel sheet S2 together.
As shown in FIG. 4, a punch hole H is formed in a welded portion 30 between a preceding steel sheet S1 and a following steel sheet S2 or in the vicinity of the welded portion 30 in order to identify the traveling position of the welded portion 30.
Here, it is preferable that the punch hole H is formed within an area of a distance L (0 mm≦L≦500 mm) from the welded portion 30 in the traveling direction F of the steel sheet S. Furthermore, when the punch hole H is formed in the welded portion 30, there is a risk of a decrease in the joining strength, so it is preferable to form the punch hole H at a position 10 mm or more away from the welded portion 30 in the traveling direction F of the steel sheet S.

As shown in FIG. 2, the punch hole H is formed by punching from one surface of the steel sheet S, and a burr portion P is formed on the other surface of the steel sheet S.
Here, the thickness of the steel plate S is within a range of 0.2 mm to 3.2 mm, the diameter of the punch hole H is within a range of 5 mm to 20 mm, and the protruding height of the burr portion P is 1 mm or less.
2, when punched hole H passes through the plating bath, excess molten zinc Z adheres to punched hole H, and the excess molten zinc Z tends to accumulate particularly in burr portion P. In this way, when punched hole H with excess molten zinc Z adhered thereto passes between wiping nozzles 18, the molten zinc Z is scattered by the wiping gas, causing clogging of wiping nozzles 18.

Therefore, in the hot-dip metal plating equipment 10 of this embodiment, as shown in FIG. 3, a wiping-nozzle clogging prevention device 20 of this embodiment is provided.
This wiping nozzle clogging prevention device 20 comprises a weld tracking information acquisition unit 21 that acquires tracking information of the weld 30 using a punch hole H formed at or near the weld 30 between a leading steel sheet S1 and a trailing steel sheet S2, a removal gas injection means 22 that injects a removal gas toward the position where the steel sheet passes between the wiping nozzles 18, and a control unit 23 that gives an instruction to the removal gas injection means 22 to inject removal gas toward the punch hole H when the punch hole H passes from the plating bath between the wiping nozzles 18 based on the position information of the punch hole H from the weld tracking information acquisition unit 21.

The welding part tracking information acquisition unit 21 can be configured, for example, to arrange a light emitting unit and a light receiving unit on either side of the traveling steel plate S in the traveling path of the steel plate S, and when a punch hole H passes, the light receiving unit receives a light signal from the light emitting unit to grasp the traveling position of the punch hole H and to determine the subsequent traveling position of the punch hole H from the traveling speed of the steel plate S.

Here, the removal gas injection means 22 needs to be arranged at least on the side of the steel sheet S on which the burr portion P of the punch hole H is formed, but the removal gas injection means 22 may be arranged on both sides of the steel sheet S.
Moreover, the removal gas jetting means 22 is preferably disposed at a position farther away from the bath surface of the coating bath than the wiping nozzle 18. In this embodiment, as shown in Fig. 3, the steel sheet S that has passed through the coating bath is pulled out vertically upward, and the removal gas jetting means 22 is disposed above the wiping nozzle 18.
Furthermore, it is preferable that the removal gas jetting means 22 is configured so that the jetting angle θ of the removal gas is adjustable.

Here, in this embodiment, as shown in Figure 3, the removal gas injection means 22 is configured to inject the removal gas diagonally downward, and it is preferable that the injection angle θ of the removal gas (the angle θ with the steel plate S pulled vertically upward) is within the range of 45° or more and 80° or less.
The jet angle θ may be appropriately set so that the removal gas can be jetted toward the punch hole H immediately before the welded portion 30 passes between the wiping nozzles 18 .

In addition, it is preferable that the horizontal distance L1 of the tip position of the removal gas injection means 22 from the steel sheet S pulled vertically upward is 100 mm or more, and the vertical distance L2 from the injection port of the wiping nozzle 18 is 120 mm or more.

Furthermore, in this embodiment, in order to accurately remove the molten zinc Z adhering to the punch hole H, it is preferable that the discharge pressure of the removal gas jetted from the removal gas jetting means 22 is 0.1 MPa or more, and the flow rate of the removal gas jetted from the removal gas jetting means 22 is 230 ^Nm3 /min or more.
On the other hand, there is no particular upper limit on the discharge pressure and flow rate of the removal gas, but in order to suppress interference with the wiping gas, it is preferable to set the discharge pressure of the removal gas to 0.5 MPa or less and the flow rate of the removal gas to 700 Nm ³ /min or less.
The lower limit of the discharge pressure of the removal gas is more preferably 0.18 MPa or more, and the upper limit of the discharge pressure of the removal gas is more preferably 0.30 MPa or less. The lower limit of the flow rate of the removal gas is more preferably ³⁵⁰ Nm3/min or more, and the upper limit of the flow rate of the removal gas is more preferably 450 ^Nm3 /min or less.

In addition, since there is a risk that the traveling steel sheet S will move in the width direction and the widthwise positions of the punched holes H will fluctuate, it is preferable that the injection width W of the removal gas from the removal gas injection means 22 be 200 mm or more.
In this embodiment, as shown in Fig. 4, the wiping nozzle 18 is arranged to be wider than the width of the steel sheet S, and the nozzle of the removal gas jetting means 22 is arranged in the center in the width direction of the steel sheet S. The nozzle width (jet width of the removal gas) W of the removal gas jetting means 22 is set to 200 mm or more. There is no particular limit to the number of nozzles of the removal gas jetting means 22, and it is sufficient that the configuration can ensure the jet width W.

According to the wiping nozzle clogging prevention device 20 and the wiping nozzle clogging prevention method of this embodiment configured as described above, when the punch hole H passes between the wiping nozzle 18 and the plating bath, a removal gas is sprayed toward the punch hole H based on information from the welding part tracking information acquisition unit 21, and the molten zinc Z adhering to the punch hole H is removed, so that clogging of the wiping nozzle 18 can be prevented. This makes it possible to suppress the occurrence of poor appearance due to clogging of the wiping nozzle 18.

In addition, in this embodiment, the removal gas injection means 22 is disposed at a position farther away from the bath surface of the plating bath than the wiping nozzle 18. In this embodiment, the steel sheet S that has passed through the plating bath is pulled vertically upward. When the removal gas injection means 22 is disposed above the wiping nozzle 18, the wiping nozzle 18 can be positioned close to the bath surface of the plating bath. Even if the plating bath contains elements that are easily oxidized, the amount of plating adhesion can be precisely adjusted by the wiping nozzle 18 before the molten metal adhering to the steel sheet S oxidizes.

Furthermore, in this embodiment, if the removal gas injection means 22 is configured to be able to change the injection angle θ of the removal gas, the injection angle θ can be set so that the removal gas can be injected toward the punch hole H just before the welded portion 30 passes between the wiping nozzles 18. This makes it possible to remove the molten metal adhering to the punch hole H before the punch hole H passes between the wiping nozzles 18, and to prevent clogging of the wiping nozzles 18.

In addition, in this embodiment, the injection angle θ of the removal gas (the angle θ with the steel plate S pulled vertically upward) is set within the range of 45° or more and 80° or less, making it possible to accurately remove the molten metal adhering to the punch hole H.
Furthermore, in this embodiment, the tip position of the removal gas injection means 22 is set at a horizontal distance L1 of 100 mm or more from the steel plate S pulled vertically upward, and at a vertical distance L2 of 120 mm or more from the nozzle of the wiping nozzle 18, thereby suppressing interference with other components.

In addition, in this embodiment, when the discharge pressure of the removal gas is set within the range of 0.1 MPa or more and 0.5 MPa or less, and the flow rate of the removal gas sprayed from the removal gas spraying means 22 is set within the range of 230 Nm ³ /min or more and 700 Nm ³ /min or less, it is possible to stably remove the molten metal adhering to the punch hole H before the punch hole H passes between the wiping nozzles 18.

The above describes in detail the wiping nozzle clogging prevention device and the wiping nozzle clogging prevention method according to the embodiment of the present invention. However, the present invention is not limited to this and can be modified as appropriate without departing from the technical concept of the invention.
For example, in this embodiment, the removal gas injection means 22 is described as being arranged at a position farther away from the bath surface of the plating bath than the wiping nozzle 18, but this is not limited to this, and the removal gas injection means 22 may be arranged between the wiping nozzle 18 and the bath surface of the plating bath, as shown in Figure 5.

The results of experiments carried out to confirm the effects of the present invention will be described below.
A hot-dip galvanized layer was formed on the surface of the steel sheet S using the hot-dip galvanizing equipment equipped with the wiping nozzle clogging prevention device described above.
In the comparative example, the wiping nozzle clogging prevention device described above was not used.
In the present invention, a wiping nozzle clogging prevention device was used to spray a removal gas toward the punched hole when the punched hole passed between the wiping nozzles from the plating bath, thereby removing the molten metal adhering to the punched hole.

In the comparative example and the present invention example, approximately 10,000 tons of steel sheet was plated, and the amount and rate of appearance defects caused by clogging caused by punch holes were evaluated. Regarding clogging caused by punch holes, appearance defects that occurred at the welded part of the steel sheet or in the center of the width direction near the welded part were evaluated as "appearance defects due to clogging caused by punch holes." The evaluation results are shown in Figure 6.

In the examples of the present invention in which the wiping nozzle clogging prevention device was used, it was confirmed that the occurrence and rate of appearance defects caused by clogging due to punch holes was significantly reduced compared to the comparative example in which the wiping nozzle clogging prevention device was not used.

From the above, it has been confirmed that the present invention can provide a wiping nozzle clogging prevention device and a wiping nozzle clogging prevention method that can prevent clogging of the wiping nozzle even when a punch hole formed at or near a weld passes between the wiping nozzles, suppress the occurrence of appearance defects, and produce high-quality hot-dip metal-plated steel sheet.

10: Hot-dip metal plating equipment 18: Wiping nozzle 20: Wiping nozzle clogging prevention device 22: Removal gas injection means 23: Control unit

Claims (4)

A hot-dip metal coating facility in which a plurality of steel sheets, each formed by welding a preceding steel sheet and a following steel sheet, are successively passed through a hot-dip metal coating bath, and a wiping gas is sprayed from wiping nozzles disposed on one side and the other side of the steel sheets toward the steel sheets that have passed through the hot-dip metal coating bath to adjust a coating weight of the steel sheets, comprising: a wiping nozzle clogging prevention device that prevents clogging of the wiping nozzles,
A punch hole is formed in a welded portion or in the vicinity of the welded portion between the preceding steel sheet and the following steel sheet,
a removal gas jetting means for jetting a removal gas for removing molten zinc adhering to the punched holes toward a position where the steel sheet passes from the molten metal coating bath to between the wiping nozzles;
a control unit that issues a command to the removal gas jetting means to jet a removal gas from the molten metal coating bath toward the punch hole passing between the wiping nozzles, based on position information of the punch hole obtained by utilizing the punch hole formed at or near the welded portion between the preceding steel sheet and the following steel sheet;
Equipped with
2. A wiping nozzle clogging prevention device, comprising: a removal gas injection means disposed on at least the surface of the steel plate on which the burrs of the punched holes are formed . The wiping nozzle clogging prevention device according to claim 1, characterized in that the removal gas injection means is disposed at a position farther away from the bath surface of the molten metal plating bath than the wiping nozzle. The wiping nozzle clogging prevention device according to claim 1 or 2, characterized in that the removal gas injection means is configured to be capable of adjusting the injection angle of the removal gas. A method for preventing clogging of a wiping nozzle in a hot-dip metal coating facility in which a plurality of steel sheets, each formed by welding a preceding steel sheet and a following steel sheet, are continuously supplied to a hot-dip metal coating bath, and a wiping gas is sprayed from wiping nozzles arranged on one side and the other side of the steel sheet toward the steel sheet that has passed through the hot-dip metal coating bath to adjust a coating weight of the steel sheet, the method comprising:
A method for preventing clogging of a wiping nozzle, characterized in that a punch hole is formed at or near the welded portion between the preceding steel sheet and the following steel sheet, and when the punch hole passes from the molten metal plating bath between the wiping nozzles, a removal gas is sprayed toward the punch hole by a removal gas spraying means arranged at least on the side of the steel sheet on which the burr portion of the punch hole is formed , thereby removing molten metal adhering to the punch hole.

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