JP2798314B2 - Furnace sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floater type heat treatment furnace for continuously treating strips of metal or the like, in which a floater nozzle for carrying the strip while floating it on a hot air flow is used as a section in the furnace. Regarding improvement.

[0002]

2. Description of the Related Art In a heat treatment furnace of a continuous processing line for continuously processing a strip of metal or the like, a so-called hearth roller method using a conventional supporting roller is used as a means for conveying the strip without directly contacting the strip.
A support system called a floater system, in which a strip is conveyed while floating on a hot air flow while floating, has been adopted. In addition, the inside of the furnace is divided into a plurality of sections according to operating conditions such as atmospheric gas and temperature distribution, and the sealer installed at the position where the sections are divided is also moved up and down to avoid direct contact with the strip. An opposed seal floater is used.

[0003] In these floaters, a gas is ejected from an elongated slit-shaped nozzle corresponding to the strip width to generate a pressure between the strip and the strip according to Bernoulli's theorem. Since the magnitude of the pressure is inversely proportional to the distance between the nozzle and the strip, this distance is usually as small as 100 mm or less. For this reason, there is a defective shape part in the strip,
If there is a sudden change in tension or speed, the strip may come into contact with the nozzle and abrasion may occur at the contact portion.
Particularly, in a strip of a thin steel plate or the like, a phenomenon called “C warpage” in which the center in the width direction is convex is often seen. The cause of the C warpage is mainly a curl remaining when the strip reaches the heat treatment furnace. That is, the curl generated by the winding of the winding shaft or the bridle roll of the transport system appears as a C warp when the strip is rewound in the longitudinal direction. When the convex portion due to the C warp passes through the floater portion, a contact flaw is easily generated. To prevent this, Japanese Patent Application Laid-Open No. 60-218433
According to the publication, it is proposed to incorporate a roll that has a peripheral surface projecting toward the strip side from the tip of the gas nozzle and rotates at the same peripheral speed as the strip traveling speed, in the pressure chamber of the floater portion. FIG. 3 is a cross-sectional view thereof, wherein 1 is a strip, 5 is an upper floater, 7 is a lower floater, 11 is an upper roll, and 12 is a lower roll. With this configuration, contact between the strip and the floater can be prevented,
Since the rotating roll is installed in the pressure chamber, equipment such as a pressure seal around the drive shaft and a drive device is required, and maintenance is difficult.

Therefore, for the same purpose, a guide roller made of a material that does not cause a flaw even when the strip comes into contact is installed before and after the floater, that is, outside the pressure chamber. The guide roller rotates freely but does not drive. FIG. 4 is a cross-sectional view of an example of a seal floater provided with such a guide roller as viewed from a side surface of a continuous heat treatment furnace for strip. The strip 1 is conveyed from left to right in a heat treatment furnace composed of a furnace shell 2 and a heat insulating material 3, and undergoes necessary heat treatment during this time. In this figure, the left is A
Section, right side is section B, furnace temperature,
Since the atmosphere gas and the like are different in the two sections, a seal floater in which a floater having a slit-shaped nozzle for ejecting a gas body toward the strip is provided at the end of each section and arranged above and below the strip so as to face each other, The two seal floaters in both sections are in contact. 5 and 6 are upper floaters, 7 and 8 are lower floaters, and the upper and lower floaters 5 and 7 on the A section side receive the atmosphere gas of the A section, and the upper and lower floaters 6 and 8 on the B section side receive the atmosphere gas of the B section. The strip is blown out from each nozzle and floats and supports the strip, and at the same time, shuts off the atmosphere in the section. Upper floater 5,
Guide rollers 13 and 14 are provided before and after 6.

[0005]

By the way, this guide roller has a different effect in suppressing the C warp depending on the height at which the guide roller is installed. When the guide roller is installed lower than the lower surface of the upper floater, the effect of suppressing the C warp increases. At the same time, the guide rollers become severely worn and damaged, and the strips do not become flaws but leave a strong contact mark, resulting in a pattern that cannot be overlooked in terms of quality, so use it at almost the same level as the lower surface of the upper floater. As a result, the effect of suppressing the C warpage was insufficient.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a horizontal continuous heat treatment furnace for a strip divided into single or multiple sections, wherein a floater having a nozzle for jetting a gas body toward the strip is provided. A furnace in which seal floaters arranged vertically facing each other are arranged at the end of each section, and an atmosphere gas body of the section is jetted from each nozzle to float and support the strip and to shut off the atmosphere in the section by a gas flow. An inner sealing device for jetting an atmosphere gas of a section or a gas body having a common component to the front or rear surface of an upper floater or a lower floater from one direction toward at least a central portion in a width direction of the strip. An in-furnace sealing apparatus for a horizontal continuous heat treatment furnace, comprising a guide nozzle. .

[0007]

According to the present invention, a guide nozzle for holding down a C-warp is provided in front of and behind the upper seal floater instead of the conventional guide roller, and the furnace atmosphere gas or a gas having the same component as this is blown out. As a result, the C-warped portion can be pushed down in a non-contact manner, and can be installed at a height at which the effect of sufficiently suppressing the C-warpage is exhibited.

[0008]

FIG. 1 shows an embodiment of the present invention. This figure is
FIG. 4 is a cross-sectional view of the strip as viewed from the side of the continuous heat treatment furnace, showing only a sealing device portion. Strip 1 is transported from left to right in the furnace. In this figure, the left section is the A section, and the right section is the B section. Since the furnace temperature, atmospheric gas, etc. are different between the two sections, a slit-shaped nozzle for ejecting a gas toward the strip is provided at the end of each section. A seal floater is provided in which the floaters are arranged above and below the strip so as to face each other, and two seal floaters of both sections are in contact at a boundary portion. 5,
6 is an upper floater, 7 and 8 are lower floaters, and the upper and lower floaters 5 and 7 on the A section side are supplied with the atmosphere gas of the A section, and the upper and lower floaters 6 and 8 on the B section side are supplied with the atmosphere gas of the B section. At the same time, the strips are blown out from the respective nozzles to float and support the strip, and at the same time, the atmosphere in the section is shut off. Before and after the upper floater,
Guide nozzles 9 and 10 are provided in place of the guide rollers described above. The same gas as the upper seal 5 is used for the guide nozzle 9, and the same gas as the upper seal 6 is used for the guide nozzle 10.

FIG. 2 is a side view of the position of the guide nozzle in FIG. 1 as viewed from the traveling direction. Since the guide nozzle 10 is a slit-shaped nozzle that ejects a gas body toward at least the center portion in the width direction of the strip, the strip having the C-curvature shown by the broken line suppresses the convex portion downward by the ejected gas and the solid line. This indicates that the sheet can pass through the gap between the upper and lower floaters 6 and 8 without causing contact.

It is desirable that the mounting height of the guide nozzles 9 and 10 is equal to or slightly lower than that of the upper floaters 5 and 6. Therefore, in order to further prevent the strip from coming into contact with the guide nozzles 9 and 10, protection rollers may be provided before and after the guide nozzles 9 and 10. In addition, since the C warpage generally depends on the history of curling in the upstream process, it tends to occur in a convex or concave shape as a characteristic peculiar to a factory or a line. However, it goes without saying that the guide nozzle may be provided on the lower side in a line or the like which tends to be formed in a concave shape.

As is apparent from the above description, the in-furnace sealing apparatus of the present invention has a single-section furnace, each section of which is divided into a plurality of sections at both ends when the furnace is a single-section furnace. The object can be achieved by providing at both ends.

[0012]

According to the present invention, it has been possible to greatly reduce abrasion in a wide and thin strip in which C warpage is likely to occur. Looking at an example of a horizontal heat treatment furnace that processed a thin steel sheet with a width of 1000 to 1280 mm and a thickness of 0.35 mm, a scratch was generated in 16.2% after processing 148 coils conventionally, but for 66 coils after the implementation of the present invention, No scratches were observed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a furnace sealing device of the present invention as viewed from a side.

FIG. 2 is a side view of FIG. 1 as viewed from a traveling direction.

FIG. 3 is a side sectional view showing a conventional technique.

FIG. 4 is a side sectional view showing another conventional technique.

[Explanation of symbols]

 1 Strip 5, 6 Upper floater 7, 8 Lower floater 9, 10 Guide nozzle 13, 14 Guide roller

Claims (1)

(57) [Claims] 1. A horizontal continuous heat treatment furnace for a strip divided into a single section or a plurality of sections, in which a floater having a nozzle for jetting a gas body toward the strip is disposed above and below the strip so as to face each other. An in-furnace sealing device in which a floater is disposed at an end of each section, and an atmosphere gas body of the section is jetted from each nozzle to float and support the strip and to shut off an atmosphere in the section by a gas flow. A guide nozzle is provided on a front surface or a rear surface of the floater or the lower floater, the guide nozzle ejecting an atmosphere gas of the section or a gas having a component common to the section from one direction toward at least a widthwise central portion of the strip. In-furnace sealing device for horizontal type continuous heat treatment furnace.