JP4028990B2 - Combined production line for cold-rolled steel sheet and hot-dip galvanized steel sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cold-rolled steel sheet manufactured by switching between a cold-rolled steel sheet and a hot-dip galvanized steel sheet, which are provided with a bypass furnace for directly passing the processing material from the heat treatment furnace to the heat treatment furnace without passing through the hot dip galvanizing apparatus. The present invention relates to a combined production line for galvanized steel sheets, and particularly relates to a structure for sealing between a heat treatment furnace and a hot dip galvanizing apparatus when manufacturing cold-rolled steel sheets.
[0002]
[Prior art]
Conventionally, it is used for multiple purposes by switching the sheet passage route, for example, as a technique for using both heat treatment of cold-rolled steel sheet and hot dip galvanizing treatment, JP-A-58-71366 discloses heating zone, soaking zone, primary Cooling zone, overaging zone with controlled cooling function, hot dip galvanizing means, intermediate cooling means, secondary cooling zone, temper rolling means, chemical treatment means are arranged in series, and further from the overaging zone to secondary A combined production line for cold-rolled steel sheet and hot-dip galvanized steel sheet having bypass means leading to the cooling zone is described.
[0003]
FIG. 5 shows an example of a conventional production line for both cold-rolled steel sheets and hot-dip galvanized steel sheets. In this FIG. 5, when using as a cold-rolled steel sheet production line, the steel strip 1 which is a processing material is heated more than a recrystallization temperature in the heating zone 2 which employ | adopted the indirect heating system by a radiant tube, and then it reaches predetermined temperature. While being held, soaked in the soaking zone 3 and primary cooled to approximately 450 ° C. in the primary cooling zone 4 equipped with a gas jet cooler, then 1 to 450-300 ° C. in the primary overaging zone 5 equipped with an electric heater. It is over-aged by holding for ˜3 minutes, sent directly to the secondary overaging zone 6 via the bypass furnace 23, and further cooled to about 300 ° C. in the secondary cooling zone 7, and then water-cooled The final cooling device 8 cools to near normal temperature.
[0004]
On the other hand, when used as a hot dip galvanizing production line, the bypass furnace 23 is separated from the lead-out portion 26 and the introduction portion 27 and is retracted to a position outside the sheet passing line, and the steel strip 1 is heated to the heating zone 2, soaking zone 3 Necessary after passing through the primary cooling zone 4 and the primary overaging zone 5 in succession, subsequently introducing into the hot dip galvanizing pot 16 via the snout 10 and adjusting to a predetermined plating thickness by the wiping nozzle 18 After that, it is configured to be introduced into the intermediate cooling device 20, the secondary overaging zone 6, the secondary cooling device 7, and the final cooling device 8 through the alloying device 19. Reference numerals 21 and 22 are top rolls. In this way, by moving the bypass furnace 23 to the plate line position, or by retracting outside the plate line, the production of the cold-rolled steel sheet and the hot-dip galvanized steel sheet is switched by switching the plate-passing path of the steel strip. It is possible.
[0005]
[Problems to be solved by the invention]
In the conventional combined production line as described above, a damper type, a shutter type and a sandwich type sealing device 24 are installed between the snout side turn-down roll 9 and the snout 10, and during cold-rolled steel sheet production, This is closed, and the inside of the furnace is maintained at a positive pressure state by the in-furnace protective gas that is usually introduced into the furnace and made of a mixed gas of hydrogen and nitrogen. In the combined production line having such a configuration, when the cold-rolled steel sheet is manufactured, the steel strip 1 is passed through the bypass furnace 23, so that the hot dip galvanizing apparatus itself is stopped. However, since the turn-down roll 9 belongs to the inside of the furnace and is in a protective gas atmosphere in the furnace, maintenance and inspection work such as surface care and replacement of the turn-down roll 9 during the production of cold-rolled steel sheet. There was a problem that could not. Therefore, the surface of the turn-down roll 9 and the cleaning of the inner surface of the snout 10 can be performed only when the entire combined production line is stopped.
[0006]
In addition, the zinc vapor generated in the snout 10 whose tip is partially inserted into the hot dip galvanizing pot 16 diffuses and rises in the snout 10 and flows toward the inside of the furnace. There is a phenomenon that condensation adheres to places where the surface such as 9 is at a low temperature. When the zinc vapor condensate grows to some extent, it falls due to its own weight and adheres to the surface of the steel strip 1 and causes non-plating. Further, when the zinc vapor condenses and adheres to the roll surface, the condensate is transferred to the surface of the steel strip 1 and causes non-plating.
[0007]
The sealing device 24 installed on the snout 10 behind the turn-down roll 9 employs a damper type, a shutter type, a sandwiching type, or the like. When 24 is provided in the snout 10, there is a problem that zinc vapor generated from the hot dip galvanizing pot 16 is likely to condense in the vicinity of protrusions such as a sealing member in the sealing device. This is because the condensation of the zinc vapor flow in the snout 10 is promoted by the disturbance caused by such protrusions. In addition, when such a sealing device 24 is provided in the snout 10, there is a drawback that it becomes a great obstacle when cleaning the inner surface of the snout 10.
[0008]
Instead of providing the sealing device 24 in the snout 10, there is a method in which the tip portion of the snout 10 is once removed and a sealing end plate is attached. However, since a lot of time and labor is required for the attaching operation, the furnace can be surely and quickly completed. A means capable of sealing the inner protective gas has been desired. Therefore, in the present invention, it is possible to reliably seal without stopping the line, and to clean the turn-down roll and the hot dip galvanizing apparatus for changing the direction of the steel strip to the hot dip galvanizing apparatus during cold-rolled steel sheet production, This provides a combined line of cold-rolled steel sheet and hot-dip galvanized steel sheet that can prevent zinc from adhering to the steel sheet surface.
[0009]
[Means for Solving the Problems]
The gist of the invention is a cold-rolled steel sheet and a hot-dip galvanized steel sheet that are manufactured by switching between a cold-rolled steel sheet and a hot-dip galvanized steel sheet, provided with a bypass furnace that passes the steel strip without passing through a hot-dip galvanizing apparatus. In the combined production line, a partition plate for properly interrupting the plating passage route is installed in the furnace body immediately before the turn-down roll for introducing the steel strip toward the hot dip galvanizing apparatus, and the partition is installed. Auxiliary sealing means is installed in front of the plate insertion portion, and an expansion device is provided at the front end of one of the furnace bodies before and after the partition plate insertion portion, and when the partition plate is inserted, the expansion device and the other furnace body are interposed via the partition plate. This is a combined production line for cold-rolled steel sheets and hot-dip galvanized steel sheets, wherein the expansion device and the other furnace body are directly press-bonded when the partition plate is retracted.
[0010]
Hereinafter, the present invention will be specifically described with reference to examples.
【Example】
FIG. 1 is a view showing a state when a partition plate is inserted in a combined production line for cold-rolled steel sheets and hot-dip galvanized steel sheets according to the present invention, and FIG. 2 is a combination of cold-rolled steel sheets and hot-dip galvanized steel sheets according to the present invention. It is a figure which shows the state which carried out the press joining after the partition plate insertion in a production line, and FIG. 3 is a figure which shows the case where the hot dip galvanization in the combined production line of the cold rolled steel plate and hot dip galvanized steel plate which concerns on this invention is performed. It is. The cold-rolled steel sheet and hot-dip galvanized steel sheet combined production line according to the present invention is an example of a conventional cold-rolled steel sheet and hot-dip galvanized steel sheet combined production line as shown in FIG. By providing a bypass furnace 23 that passes a steel strip that is a processing material without passing through, it is a switch-type dual-purpose line that switches between a cold-rolled steel sheet and a hot-dip galvanized steel sheet. Since the line configuration is the same as that described in the prior art, the description is omitted here.
[0011]
FIG. 4 is a detailed view of the partition device according to the present invention. In the present invention, the partition device A is installed on the exit side of the primary overaging zone 5 and in the furnace body just before the turn-down roll 9. The partition plate 11 constituting the partition device A is suspended from the guide rail 15 by a trolley 14 and can be moved into a line from a retracted position outside the line in the illustrated state. The partition plate 11 is inserted in the furnace body part immediately before the turn-down roll 9. However, a gap is required in the furnace body in order to insert the partition plate 11. 11, a telescopic device 12 is installed at the front end of the partition plate front side furnace body 25 on the front side of the insertion portion, and a plurality of cylinders 13 are provided at the outer periphery of the front end of the telescopic device 12. Is designed to expand and contract.
[0012]
Further, on both surfaces of the partition plate 11, sealing materials 30 are respectively attached to a surface that contacts the expansion device 12 and a surface that contacts the partition plate rear side furnace body 28 on which the turn-down roll 9 is disposed. Furthermore, a heat insulating material is applied to the partition plate front side furnace body 25, that is, the surface side in contact with the primary overaging zone 5 side, and consideration is given to prevent thermal deformation of the partition plate 11.
[0013]
Next, the operation of the partition device A will be described.
When the line is switched to cold-rolled steel sheet production, the steel strip 1 is directly passed from the primary overaging zone 5 to the secondary overaging zone 6 via the bypass furnace 23 as shown in FIG. The broken line in the figure shows the hot dip galvanizing passage route. At this time, the hot dip galvanizing apparatus composed of the snout 10, the hot dip galvanizing pot 16, the wiping nozzle 18 and the like, and the turn-down roll 9 for introducing the steel strip 1 toward the hot dip galvanizing apparatus are stopped. It has become. At this time, the partition plate 11 suspended from the guide rail 15 of FIG. 4 is inserted and installed in the line, that is, immediately before the turn-down roll 9, and the primary overaging zone 5 and the hot dip galvanizing apparatus are sealed.
[0014]
In inserting the partition plate 11, first, in order to prevent the outside air from entering the primary overaging band 5, sealing is performed by the auxiliary seal device 29 installed immediately before the partition plate 11. The auxiliary sealing device 29 is, for example, a labyrinth seal, a roll seal, a gas curtain seal, or the like, and may be any seal as long as it is a sealing device that can pass the steel plate 1. In order to insert the partition plate 11, as shown in FIG. 1, the telescopic device 12 installed at the front end of the partition plate front side furnace body 25 is contracted by the cylinder 13, and is inserted into and removed from the portion where the partition plate 11 is inserted. To secure space for.
[0015]
When the partition plate 11 is installed in the line via the guide rail 15, as shown in FIG. 2, the expansion / contraction device 12 is extended by the cylinder 13, and the partition plate rear side furnace body 28 is sandwiched between the partition plate 11. Press join. With this partition plate 11, the primary overaging zone 5 and the hot dip galvanizing apparatus side are cut off, and both are completely sealed. That is, when manufacturing cold-rolled steel sheets, the partition plate 11 seals the in-furnace protective gas atmosphere on the primary overaging zone 5 side, and at the same time, zinc vapor from the hot dip galvanizing pot 16 enters the primary overaging zone 5 side. To prevent. On the other hand, it is possible to prevent the atmospheric gas composed of nitrogen and hydrogen in the primary overaging zone 5 from flowing out to the hot dip galvanizing apparatus side.
[0016]
In this way, the partition plate 11 is inserted and installed, and the turndown roll 9 and the snout 10 are opened to the atmosphere during the production of the cold-rolled steel sheet by completely sealing the primary overaging zone 5 side and the hot dip galvanizing device side. It becomes possible to perform cleaning. Moreover, in the partition device A of the present invention, since complete sealing is possible, there is no fear that atmosphere gas composed of nitrogen or hydrogen from the primary overaging zone 5 leaks to the hot dip galvanizing device side. Therefore, it becomes possible for an operator to enter and work in the furnace body where the turn-down roll 9 is installed.
[0017]
Next, switching to the hot dip galvanized steel sheet apparatus will be described.
When switching to hot-dip galvanized steel sheet production, it is necessary to retract the partition plate 11 out of the line. First, in order to prevent outside air from entering the primary overaging zone 5, sealing is performed by an auxiliary sealing device 29 installed immediately before the partition plate 11. Next, as shown in FIG. 1, the expansion device 12 is expanded and contracted by the cylinder 13 to create a gap in the furnace body. Then, the partition plate 11 is retracted out of the line along the guard rail 15. After that, as shown in FIG. 3, the expansion / contraction device 12 is extended by the cylinder 13, and the expansion / contraction device 12 is directly pressed and joined to the partition plate rear side furnace body 28. The steel strip 1 is heat-treated in the primary overaging zone 5 and then introduced into the hot dip galvanizing pot 16 from the snout 10 via the turn-down roll 9 and travels vertically upward through the sink roll 17 to the alloying device 19. Sent. At this time, the bypass furnace 23 used at the time of manufacturing the cold-rolled steel sheet is retracted outside the line so as not to disturb the traveling of the steel strip 1.
[0018]
In this embodiment, the case where the expansion / contraction device 12 is installed at the tip of the partition plate front side furnace body 25 has been described, but the expansion device 12 may be installed in the partition plate rear side furnace body 28, In the present embodiment, the case where a bypass furnace is provided between the primary overaging zone 5 and the secondary overaging zone 6 has been described, but the present invention is not limited to this. For example, the primary cooling zone and the overaging zone A bypass furnace may be provided between the two.
[0019]
【The invention's effect】
As described above, according to the present invention, by installing the partition plate so that it can be appropriately inserted immediately before the turn-down roll, a furnace for manufacturing a cold-rolled steel sheet and a hot-dip galvanizing apparatus after the turn-down roll, It is possible to completely block the gap, and the surface of the turn-down roll can be maintained or replaced using the cold-rolled steel sheet manufacturing time. Therefore, it is not necessary to stop the entire line for cleaning as in the prior art. In addition, since the barrier plate can completely shut off, the atmosphere gas consisting of nitrogen and hydrogen from the furnace does not leak to the turn-down roll side. For example, an operator enters the furnace body and cleans the turn-down roll. It is also possible to perform work.
[0020]
Moreover, since it is not necessary to provide a conventional snout seal device in the snout portion, the inner surface of the snout can be easily cleaned. Therefore, even if zinc vapor condenses on the inner surface of the snout or the turndown roll surface, it can be easily removed periodically, and the zinc vapor mass falls on the surface of the steel strip, resulting in quality defects such as non-plating. Can be prevented in advance. In addition, the partition plate can be easily moved in and out of the line by the guide rails, and the expansion device can be expanded and contracted to secure the space for inserting the partition plate, and the expansion and contraction device can be secured by the cylinder through the partition plate. Can be easily and reliably sealed against each other.
[Brief description of the drawings]
FIG. 1 is a view showing a state when a partition plate is inserted in a combined production line for cold-rolled steel sheet and hot-dip galvanized steel sheet according to the present invention.
FIG. 2 is a view showing a state in which a cold-rolled steel sheet and a hot-dip galvanized steel sheet according to the present invention are pressed and joined after inserting a partition plate in a combined production line.
FIG. 3 is a diagram showing a case where hot dip galvanization is performed in a combined production line for cold rolled steel sheets and hot dip galvanized steel sheets according to the present invention.
FIG. 4 is a detailed view of the partition device according to the present invention.
FIG. 5 is a diagram showing an example of a conventional production line for both cold-rolled steel sheets and hot-dip galvanized steel sheets.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel strip 2 Heating zone 3 Soaking zone 4 Primary cooling zone 5 Primary overaging zone 6 Secondary overaging zone 7 Secondary cooling zone 8 Final cooling device 9 Turndown roll 10 Snout 11 Partition plate 12 Telescopic device 13 Cylinder 14 Trolley 15 Guide rail 16 Hot dip galvanizing pot 17 Sink roll 18 Wiping nozzle 19 Alloying device 20 Intermediate cooling devices 21 and 22 Top roll 23 Bypass furnace 24 Snout seal device 25 Partition plate front side furnace body 26 Deriving portion 27 Introduction portion 28 Partition plate rear Side furnace body 29 Auxiliary sealing device 30 Sealing material A Partition device

Claims (1)

Hot-dip galvanization in the combined production line of cold-rolled steel sheet and hot-dip galvanized steel sheet, which is manufactured by switching between cold-rolled steel sheet and hot-dip galvanized steel sheet. In the furnace body immediately before the turn-down roll for introducing the steel strip toward the apparatus, a partition plate for appropriately interrupting the plating plate passage is installed so as to be freely inserted and retracted, and auxiliary seal means is provided in front of the partition plate insertion portion. In addition, an expansion / contraction device is provided at the front end of one of the furnace bodies before and after the partition plate insertion part. When inserting the partition plate, the expansion device and the other furnace body are pressed and joined via the partition plate, and the partition plate is retracted. Is a combined production line for cold-rolled steel sheets and hot-dip galvanized steel sheets, characterized in that the expansion device and the other furnace body are directly pressed and joined.

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