JP2003247025A - Production line used for both cold-rolled steel sheet and galvanized steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production line used for both a cold-rolled steel sheet and a galvanized steel sheet with which cleanings of turn-down rolls for changing the direction of the steel sheet to a galvanizing apparatus during producing the cold-rolled steel sheet and the galvanizing apparatus can be performed by surely performing sealing without stopping the line and in this way, the sticking of zinc to the surface of the steel sheet can be prevented. <P>SOLUTION: In the production line used for producing the cold-rolled steel sheet and the galvanized steel sheet by changing over the cold-rolled steel sheet, that is provided with a bypass furnace passing through the steel sheet without passing through the galvanizing apparatus and the galvanized steel sheet, a partition plate for timely shutting down the galvanizing sheet passing course, is disposed so as to be freely inserted/retreated, in the furnace body just before the turn-down roll for introducing the steel sheet toward the galvanizing apparatus, and an auxiliary sealing means is disposed at the front side of the inserting part of this partition plate. Further, this line is constituted by arranging an expandable device at the tip end part of the furnace body in either one at the front side or the rear side of the inserting part of this partition plate, so that the expandable device is forcibly brought into contact with the other furnace body through this partition plate when the partition plate is inserted, and the expandable device is forcibly brought into direct contact with the other furnace body when the partition plate is retreated. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling apparatus provided with a bypass furnace for directly passing a processing material from a heat treatment furnace to a heat treatment furnace without passing through a hot-dip galvanizing apparatus. This is related to a production line for both cold-rolled steel sheets and hot-dip galvanized steel sheets that are manufactured by switching between steel sheets and hot-dip galvanized steel sheets. It is. 2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No. Sho 58-7 discloses a technique which is used for various purposes by switching a threading path, for example, a technique in which heat treatment of a cold-rolled steel sheet and hot-dip galvanizing are used in combination.
No. 1366 discloses a heating zone, a soaking zone, a primary cooling zone, an overaging zone having a control cooling function, a hot-dip galvanizing means, an intermediate cooling means, a secondary cooling zone, a temper rolling means, and a chemical treatment means. A combined production line for cold-rolled steel sheet and hot-dip galvanized steel sheet, which is arranged in series and further has a bypass means leading from the overaging zone to the secondary cooling zone, is described. FIG. 5 shows an example of a conventional production line for cold rolled steel sheets and hot-dip galvanized steel sheets. In FIG. 5, when used as a cold rolled steel sheet production line, a heating zone 2 employing an indirect heating method using a radiant tube is used.
In the first step, the steel strip 1 as a treatment material is heated to a temperature higher than the recrystallization temperature, and then is soaked in the soaking zone 3 while maintaining the temperature at a predetermined temperature. It is cooled and then over-aged by holding it at 450-300 ° C. for 1-3 minutes in the primary over-age zone 5 equipped with an electric heater,
Then, it is sent directly to the secondary overaging zone 6, further cooled to approximately 300 ° C. in the secondary cooling zone 7, and then cooled to near normal temperature by the water-cooled final cooling device 8. On the other hand, when the steel strip 1 is used as a hot-dip galvanizing production line, the bypass furnace 23 is separated from the lead-out section 26 and the introduction section 27 and is evacuated to a position outside the threading line. Smooth tropical zone 3, primary cooling zone 4, primary overaging zone 5 are passed sequentially, followed by snout 10
And then adjusted to a predetermined plating thickness by a wiping nozzle 18 and, if necessary, through an alloying device 19 and then an intermediate cooling device 2.
0, secondary overage zone 6, secondary cooling device 7, final cooling device 8
It is configured to be introduced to Note that reference numeral 21,
22 is a top roll. In this way, by moving the bypass furnace 23 to the sheeting line position, or by evacuating it outside the sheeting line, the sheeting path of the steel strip is switched to manufacture cold-rolled steel sheets and hot-dip galvanized steel sheets. Making it possible. [0005] In the conventional dual-purpose production line as described above, between the snout-side turndown roll 9 and the snout 10, a sealing device such as a damper type, a shutter type and a sandwich type is provided. 24, which is closed during the production of the cold-rolled steel sheet, and the inside of the furnace is maintained at a positive pressure by a protection gas introduced into the furnace, usually comprising a mixed gas of hydrogen and nitrogen. ing. In the combined production line having such a configuration, the steel strip 1 is passed through the bypass furnace 23 during production of the cold-rolled steel sheet, so that the hot-dip galvanizing apparatus itself is in a stopped state. However, since the turndown 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 maintenance and replacement of the turndown roll 9 during production of the cold rolled steel sheet. There was a problem that can not be. Therefore, the turndown roll 9
Can be performed only when the entire combined production line is stopped. [0006] Zinc vapor generated in the snout 10 having a tip partially inserted into the hot-dip galvanizing pot 16 diffuses inside the snout 10 and rises, and flows toward the inside of the furnace, thereby causing the inside wall of the snout 10 and the like to pass through. There is a phenomenon that the surface of the turndown roll 9 or the like is condensed and adhered to a portion where the temperature is low. When the condensed lump of zinc vapor grows to some extent, it falls under its own weight and adheres to the surface of the steel strip 1 or the like, causing non-plating. Further, when zinc vapor is condensed and adhered to the roll surface, the condensed lump was transferred to the surface of the steel strip 1 to cause non-plating. The seal device 24 installed on the snout 10 behind the turndown roll 9 is of a damper type.
Although a shutter type and a sandwich type are used, any type of such a sealing device 2 is used.
4 is provided on the snout 10, the hot-dip galvanized pot 1
There is a problem that the zinc vapor generated from No. 6 tends to be condensed near protrusions such as a seal member in the seal device. This is because the condensation of the flow of the zinc vapor in the snout 10 is promoted by the turbulence caused by such projections.
In addition, if such a sealing device 24 is provided in the snout 10, there is a drawback that it is very difficult to clean the inner surface of the snout 10. [0008] Instead of providing the snout 10 with the sealing device 24, there is also a method of once removing the tip portion of the snout 10 and attaching a sealing head plate. Means that can reliably seal the protective gas in the furnace have been desired. Therefore, in the present invention, the line is reliably sealed without stopping, and it is possible to clean the turn-down roll and the hot-dip galvanizing apparatus for turning the direction of the steel strip to the hot-dip galvanizing apparatus during the production of the cold-rolled steel sheet, This provides a line for both cold-rolled steel sheets and hot-dip galvanized steel sheets that can prevent zinc from adhering to the steel sheet surface. The gist of the present invention is to provide a by-pass furnace for passing a steel strip without passing through a hot-dip galvanizing apparatus, so that a cold-rolled steel sheet and a hot-dip galvanized steel sheet can be separated. In a combined production line for cold-rolled steel sheets and hot-dip galvanized steel sheets that are switched and manufactured, the furnace body immediately before the turn-down roll that introduces the steel strip toward the hot-dip galvanizing equipment is used to appropriately block the plating passage route. A partition plate is installed so as to be able to be inserted and retracted, auxiliary sealing means is installed in front of the partition plate insertion portion, and further, a telescopic device is provided at one end of the furnace body before or after the partition plate insertion portion. A cold-rolled steel sheet and hot-dip galvanizing, wherein the expansion device and the other furnace body are pressure-bonded via the partition plate, and when the partition plate is retracted, the expansion device and the other furnace body are directly bonded to each other. Combined production of steel sheets Line. Hereinafter, the present invention will be described specifically with reference to examples. FIG. 1 is a view showing a state in which a partition plate is inserted in a production line for both a cold-rolled steel sheet and a hot-dip galvanized steel sheet according to the present invention, and FIG. It is a figure which shows the state which carried out the pressure joining after the partition plate insertion in the combined production line of a galvanized steel sheet, and FIG. 3 performs the hot-dip galvanizing in the combined production line of the cold-rolled steel sheet and the galvanized steel sheet which concerns on this invention. It is a figure showing a case. Incidentally, as shown in FIG. 5, which is an example of a conventional production line for cold rolled steel sheets and hot dip galvanized steel sheets, a hot dip galvanizing apparatus is used as a cold rolled steel sheet and hot dip galvanized steel sheet production line. By providing a bypass furnace 23 for passing a steel strip as a processing material without passing through, a switchable dual-purpose line that switches between cold-rolled steel sheets and hot-dip galvanized steel sheets and manufactures them. The line configuration is the same as that described in the related art, and the description is omitted here. FIG. 4 is a detailed view of the partitioning device according to the present invention. In the present invention, the partitioning device A is installed on the exit side of the primary overaging zone 5 and in the furnace immediately before the turndown roll 9. The partition plate 11 constituting the partitioning device A is suspended from the guide rail 15 by the trolley 14, and can be moved into the line from the retracted position outside the line in the state shown in the drawing. The partition plate 11 is inserted into the furnace body immediately before the turn-down roll 9, but a gap is required in the furnace body to insert the partition plate 11, and in the present invention, the partition plate is inserted. A telescopic device 12 is installed at the front end of a partition plate front side furnace body 25 on the front side of the insertion part 11, and a plurality of cylinders 13 are provided on the outer peripheral portion of the front end of the telescopic device 12. To expand and contract. On both sides of the partition plate 11, a telescopic device 12 is provided.
The seal member 30 is attached to each of the surface that comes into contact with the partition plate and the surface that comes into contact with the rear-side furnace body 28 on which the turndown roll 9 is disposed. Further, a heat insulating material is provided on the front side of the partition plate furnace body 25, that is, on the surface side in contact with the primary overaging zone 5 side, so that thermal deformation of the partition plate 11 is prevented. Next, the operation of the partitioning device A will be described. When the line is switched to cold rolled steel sheet production, as shown in FIG. 1, the steel strip 1 is passed directly from the primary overaging zone 5 to the secondary overaging zone 6 via the bypass furnace 23. The broken line in the drawing indicates the hot-dip galvanized sheet passing path. At this time, the hot-dip galvanizing apparatus including 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 in a stopped state. Has become. At this time, the partition plate 1 suspended on the guide rail 15 of FIG.
Reference numeral 1 is inserted and installed in the line, that is, immediately before the turndown roll 9, and seals the primary overaging zone 5 and the hot-dip galvanizing apparatus. When the partition plate 11 is inserted, first, in order to prevent outside air from entering the primary overage zone 5,
Sealing is performed by the auxiliary sealing device 29 installed immediately before the partition plate 11. The auxiliary seal 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 the seal device 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 end of the front furnace body 25 of the partition plate is moved to the cylinder 13.
As a result, a space for taking in and out of the portion where the partition plate 11 is inserted is secured. When the partition plate 11 is installed in the line via the guide rail 15, as shown in FIG.
2 is extended by the cylinder 13 and sandwiches the partition plate 11 so as to be press-joined to the furnace body 28 on the rear side of the partition plate. 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, at the time of manufacturing the cold-rolled steel sheet, the protective gas atmosphere in the furnace on the side of the primary overaging zone 5 is sealed by the partition plate 11, 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 atmosphere gas composed of nitrogen and hydrogen in the primary overaging zone 5 from flowing out to the galvanizing apparatus side. By inserting the partition plate 11 in this way and completely sealing the primary overaging zone 5 side and the hot dip galvanizing apparatus side, the turndown roll 9 and the snout 10 can be removed during the production of the cold rolled steel sheet. It is possible to open to the atmosphere and perform cleaning. Further, in the partitioning device A of the present invention, since complete sealing is possible, there is no fear that the atmospheric gas composed of nitrogen and hydrogen from the primary overaging zone 5 leaks to the galvanizing apparatus side. Therefore, it is also possible for an operator to enter the furnace body where the turndown roll 9 is installed and work. Next, switching to a hot-dip galvanized steel sheet apparatus will be described. When switching to hot-dip galvanized steel sheet manufacturing, it is necessary to retract the partition plate 11 out of the line.
First, in order to prevent outside air from entering the primary overage zone 5, the auxiliary sealing device 2 installed immediately before the partition plate 11 is used.
9. Sealing is performed. Next, as shown in FIG. 1, the expansion and contraction device 12 is expanded and contracted by the cylinder 13 to form a gap in the furnace body. Then, the partition plate 11 is retracted out of the line along the guard rail 15. Thereafter, as shown in FIG. 3, the telescopic device 12 is extended by the cylinder 13 and the telescopic device 1 is extended.
2 is directly pressed and joined to the rear wall 28 of the partition plate. Steel strip 1
Is heat-treated in the primary overageing zone 5 and then from the snout 10 via the turndown roll 9 to the hot-dip galvanizing pot 16
And travels vertically upward via the sink roll 17 and is sent to the alloying device 19. 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 hinder the traveling of the steel strip 1. In this embodiment, the extension device 12 is used.
Is described at the front end of the partition plate front-side furnace body 25.
In this embodiment, the primary overage zone 5
Although the case where a bypass furnace is provided between the secondary cooling zone and the secondary overaging zone 6 has been described, the invention is not limited to this. For example, a bypass furnace may be provided between the primary cooling zone and the overaging zone. is there. As described above, according to the present invention, the partition plate can be appropriately inserted immediately before the turn-down roll, so that the furnace for manufacturing the cold-rolled steel plate and the turn-down furnace can be used. It is possible to completely shut off the hot-dip galvanizing device after the roll, and to perform the maintenance or replacement of the surface of the turndown roll using the time of manufacturing the cold-rolled steel sheet. Therefore, it is not necessary to stop the entire line for cleaning as in the related art. In addition, since the partition plate can completely shut off the gas, the atmosphere gas consisting of nitrogen and hydrogen from the furnace does not leak to the turndown roll side.For example, a worker enters the furnace body to clean the turndown roll. It is also possible to do work. Further, since it is not necessary to provide a conventional snout sealing 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 surface of the turndown roll, it can be easily removed periodically, and the zinc vapor lumps fall on the steel strip surface, causing quality defects such as non-plating. Can be prevented from occurring. In addition, the partition plate can be easily moved in and out of the line by the guide rail, and by expanding and contracting the telescopic device, a space for inserting the partition plate can be secured. Can be easily and reliably sealed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a state in which a partition plate is inserted in a production line for both a cold-rolled steel sheet and a hot-dip galvanized steel sheet according to the present invention. FIG. 2 is a view showing a state where a cold rolled steel sheet and a hot-dip galvanized steel sheet according to the present invention are joined by pressure after insertion of a partition plate in a production line. FIG. 3 is a view showing a case where hot-dip galvanizing is performed in a production line for both cold-rolled steel sheets and hot-dip galvanized steel sheets according to the present invention. FIG. 4 is a detailed view of a partition device according to the present invention. FIG. 5 is a diagram showing an example of a conventional production line for cold rolled steel sheets and hot-dip galvanized steel sheets. [Description of Signs] 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 device 21, 22 Top roll 23 Bypass furnace 24 Snout seal device 25 Partition plate front side furnace body 26 Outgoing part 27 Introduction Part 28 partition plate rear side furnace body 29 auxiliary sealing device 30 sealing material A partitioning device

Claims (1)

Claims: 1. A cold-rolled steel sheet and a hot-dip galvanized steel sheet which are provided with a bypass furnace for passing a steel strip without passing through a hot-dip galvanizing apparatus, and which are manufactured by switching between a cold-rolled steel sheet and a hot-dip galvanized steel sheet. In the combined production line for plated steel sheets, a partition plate for appropriately blocking the plating passage route is installed in the furnace immediately before the turndown roll that introduces the steel strip toward the hot-dip galvanizing device, and is removably installed. Auxiliary sealing means is installed in front of the partition plate insertion portion, and an expansion device is provided at one of the front and rear ends of the furnace body at the front or rear of the partition plate insertion portion. When the partition plate is inserted, the expansion device and the other furnace are connected via the partition plate. A production line for cold rolled steel sheets and hot-dip galvanized steel sheets, wherein the expansion and contraction device and the other furnace body are directly pressed and joined when the partition plate is retracted.