JPH03253518A - Sealing method for atmosphere treatment of band-shaped material - Google Patents

Abstract

PURPOSE:To prevent the leakage of an atmosphere gas and to prevent the generation of contact flaws on a steel sheet by providing purging chambers of the atmosphere pressure lower than the atmosphere of a bright annealing furnace for steel sheets and higher than the outdoor air pressure in the steel sheet inlet and outlet parts of the annealing furnace and pressing the steel sheet with the relatively small pressure of felt, etc., thereby sealing the atmosphere. CONSTITUTION:Plural stages of atmosphere sealing devices consisting of elastic bodies 3, such as felt, and pressing metals 4 are provided in the inlet and outlet sides of the annealing furnace for the steel sheet 2 and the felt 3 consisting of the elastic bodies is lightly pressed to the steel sheet 2 at the time of continuously passing the steel sheet 2 through the inside of the annealing furnace 1 in which the reducing gaseous atmosphere of gaseous Ax, etc., is maintained and executing bright annealing. The purging chambers 5 are provided between the annealing furnace 1 and the atm. side and gas, such as N2, is supplied from nozzles 6 to the purging chambers 5 to maintain the atmosphere pressures higher in the order of the atm. side, the purging chambers 5 and the annealing furnace. The contamination of the gaseous Ax in the furnace with the N2 is obviated and the generation of the flaws on the surface of the steel sheet is prevented by lightly pressing the steel sheet 2 with the felt 3.

Description

[Detailed Description of the Invention] [Industrial Utilization] The present invention provides a sealing method in atmosphere treatment of a strip material;
For example, it relates to a sole method in bright annealing of strips.

[Prior Art] As an atmospheric treatment for a strip-shaped material, for example, in continuous bright annealing of a strip, a sealing device is provided at the entrance and exit to prevent the atmospheric gas in the furnace from leaking. In this case, if the pressing force of the annealing furnace sealing device against the strip is increased in order to prevent the leakage of atmospheric residue, excessive tension is applied to the strip during annealing, causing the strip to warp. Due to this, creases may occur in the vertical direction. For this reason, is it necessary to reduce the contact resistance applied to the strip by lowering the pressing force of the sealing device against the strip (hereinafter referred to as low contact resistance strip threading)? In this case, the furnace atmosphere from the sealing device Due to the problem of increased gas leakage, the furnace atmosphere gas, for example, AX scum (82
25%, 8275%), safety issues also arise.

FIG. 2 is a schematic diagram showing an example of a conventional sealing device in a furnace for continuously bright annealing a strip material 2 running continuously in six directions of arrows. The sealing device prevents the leakage of the furnace atmosphere gas by sandwiching the band-shaped material 2 between the pressing hardware 4 and the felt member 3A. In this case, by increasing the pressing force of the felt member 3A, the adhesiveness between the felt member 3A and the strip material 2 can be increased, and leakage of the furnace atmosphere residue can be prevented. However, in order to perform low contact resistance threading, is it necessary to reduce the pressing force of the felt member 3A? In this case, the adhesion between the felt member 3A and the strip material 2 will deteriorate, making it impossible to prevent the leakage of the furnace atmosphere gas. Enough is enough.

Normally, the pressure inside the continuous bright annealing furnace is set higher than the outside pressure, so expensive furnace gas (inert scum, reducing gas, etc.) leaks out of the furnace through the sealing device, and the excess gas is replaced with new one. It is necessary to replenish the water, which leads to an increase in costs.

JP-A-61-153237 as a sealing device for the entrance and exit of the furnace
According to No. 3, a roll sealing device consisting of pairs of rollers 8 and 8 is provided in multiple stages at the entrance and exit of a furnace 1 as shown in FIG. It is being This method requires that the static pressure in the intermediate section 9 be equal to or higher than that in the furnace. Therefore, in consideration of the intrusion of purge scum from the intermediate section 9 into the furnace, the composition of the purge scum must be the same as that of the furnace atmosphere gas, which requires additional expensive furnace atmosphere gas. . Furthermore, if the pressure in the intermediate section 9 is set higher than the furnace internal pressure, expensive furnace atmosphere scum is likely to leak from the sealing device. Furthermore, in order to reduce the contact resistance, it is necessary to reduce the pressing force of the roller 8 against the strip-shaped material 2 or to rotate the roller 8 in accordance with the feeding speed of the strip-shaped material 2. However, if the pressing force is reduced, the amount of leakage of the furnace atmosphere gas will increase, and on the other hand, it is technically difficult to synchronize the rotation of the roller 8 with the feed rate of the metal strip 2 with high precision, and the It is difficult to simultaneously prevent leakage of internal atmosphere gas.

[Problems to be Solved by the Invention] The present invention aims to run the strip material with low contact resistance and reduce the expensive pressure from the sealing device in order to prevent the occurrence of folding defects in the strip material during atmospheric treatment of the strip material. The purpose is to prevent leakage of atmospheric gas in the furnace, and it is possible to simultaneously achieve low contact resistance and reduce the amount of atmospheric gas leaking from the atmosphere processing chamber, which were previously incompatible.

[Means and effects for solving the problems] The present invention provides an elastic body that communicates with the inlet and/or outlet of the atmosphere treatment chamber of the strip-shaped material and lightly contacts or approaches both surfaces of the strip-shaped material. The atmosphere of the strip-shaped material is arranged in multiple stages at appropriate intervals along the traveling direction of the material, and the pressure between each of the elastic bodies in the multiple stages is set to be lower than the pressure of the atmosphere treatment chamber and higher than atmospheric pressure. This is a sealing method in processing.

The atmosphere treatment chamber in the present invention is a chamber for carrying out a reforming treatment of a strip material using an atmosphere gas that has a pressure higher than the pressure inside the room or the outside air and has a composition different from that of the outside air, such as ammonia. This is a continuous bright annealing furnace for stainless steel sheets that uses a decomposed gas atmosphere.

The present invention will be explained below with reference to FIG. Reference numeral 1 shown in FIG. 1 is an atmosphere treatment chamber (for example, a continuous bright annealing furnace), in which a band-shaped material (for example, a strip) 2 is continuously passed in the direction of arrow A or arrow B and annealed. Atmosphere treatment chamber 1
Elastic bodies (for example, felt members) 3 that come into light contact with or approach both surfaces of the strip material 2 are provided at appropriate intervals along the direction of movement of the strip material 2 (two stages in the figure) at the exit or outlet of the strip material 2. , the upper elastic body 3 is in close contact with the atmosphere treatment chamber 1. When the elastic body 3 comes into contact with the strip material,
It is desirable that the frictional resistance is small and that it does not cause scratches on the strip material.

Lightly contacting or coming close to each other means that the elastic body 3 and the strip material 2
The elastic body 3 and the strip-shaped material 2 come into complete surface contact from the gap between the two or from the open state within a range where the differential pressure between the processing chamber pressure and the outside air pressure can be secured, and the elastic body 3 is further subjected to elastic deformation. It refers to the state of being.

Hereinafter, this state will be abbreviated as light contact.

Reference numeral 4 denotes a metal fitting for pressing the elastic body 3 against the band-shaped material 2. The elastic body 3 and the pressing hardware 4 are not limited to this example, and may be made by wrapping a cylindrical felt around the circumferential surface of an idling roller. A purge chamber 5 is provided between adjacent elastic bodies 3.3 in close contact with the elastic bodies 3.3,
Reference numeral 6 denotes a pair of nozzles installed in the purge chamber 5 for ejecting purge gas. For example, N2 gas is supplied to the purge chamber 5 through a nozzle 6 as a gas having a higher mass density than the furnace atmosphere gas.
More squirts and filling. The pressure within the purge chamber 5 located between the elastic bodies 3 and 3 of each part is set to be lower than the pressure within the atmosphere processing chamber 1 and higher than the outside air. As a result, the pressure in each part is set to be lower in the order of atmosphere processing chamber 1, purge chamber 5, and outside air. If the pressure in the purge chamber 5 is made higher than the pressure in the atmosphere treatment chamber 1, purge gas will mix into the atmosphere treatment chamber 1 from the purge chamber 5, and the atmosphere in the atmosphere treatment chamber 1 will be contaminated. Further, if the pressure in the atmosphere processing chamber 1 and the pressure in the purge chamber 5 are made the same, macroscopic gas flow can be prevented, but the atmosphere in the atmosphere processing chamber 1 will be contaminated due to diffusion.

Atmospheric gas in the atmosphere treatment chamber 1 flows into the purge chamber 5 through the gap 7 between the elastic body 3 and the strip-shaped material 2, but the pressure difference between the atmosphere treatment chamber 1 and the purge chamber 5 Because it is set to be smaller than the differential pressure with the outside air,
As detailed below, from the atmosphere treatment chamber 1 to the purge chamber 5
The amount of atmospheric gas leaking through the atmosphere to the outside air is smaller than the amount of atmospheric gas leaking directly from the atmosphere processing chamber 1 to the outside air.

The reason why the amount of leakage of atmospheric gas is reduced by the present invention will be explained below.

First, in FIG. 2, directly from the atmosphere treatment chamber 1 to the outside air,
When atmospheric gas is released, the pressure inside the atmospheric processing chamber is Pl, the atmospheric gas density is ρ1, the leakage flow rate is QAI, the gap area is SAl, and the outside air pressure is P. shall be. Here, the pressure inside the atmosphere treatment chamber is the differential pressure (gauge pressure) with the outside pressure.
. Let be 0. In this case, the relationship between the processing chamber pressure P1 and the leakage flow rate QAI is expressed by the following equation (1).

p, = c, -ρ1・QAI”/SAI
...(1) Here, C3 is a constant.

In Figure 1, when atmospheric gas leaks from the atmospheric processing chamber 1 to the outside air through the purge chamber 5, the pressure inside the atmospheric processing chamber is Pl, the atmospheric gas density is ρ1, the gas flow rate leaking from the atmospheric processing chamber to the purge chamber is QA, gap area is SA, purge gas flow rate is Qc, purge scum density is ρ3, purge chamber pressure is P2, purge chamber gas density is ρ2, gas flow rate leaking from purge chamber 5 to outside air is Qe, gap area is 5
8, then similarly to equation (1), equation (2) and equation (3)
).

p, -p2=c2・ρ1・QA2/5A2−...(2
)p2=c,・ρ2・Qa'/Sa2
...(3) Here, C2 and C3 are constants.

Also, according to the law of conservation of mass, QA・ρ++Qc・ρ3=Q8・ρ2 ・−
The relationship (4) holds true.

When the pressing force of the elastic body 3.3 changes, the area of the gap 7 also changes, so here, the comparison will be made under the condition that the pressing force is the same. The length of the gap 7 in Figure 2 is LA.

Assuming the lengths of the gap 7.7 in Figure 1 as LB and Lc, LA = 180LC-(5) L, =Lc
... (6), the surface pressure at each contact portion will be equal, and each gap area will also be equal.

Under these conditions, a comparison with the conventional method will be made. From equations (1) and (2), QAI' QA '= (p+/c+ +P2/C2
) ・C4...(7) Here, C4=SA/ρ1-(a) SA:SA1
...(9) p, > p2
...(10) No. (7)
In the equation, the right-hand side is clearly positive, so QAI” >
QA' ”...(11) Here, QAI>Ol QA>O...(12) Therefore, QAI>QA...
(13) That is, when the pressure inside the purge chamber 5 is set lower than the pressure inside the atmosphere treatment chamber 1 and higher than the outside pressure in FIG. 1, the leakage flow rate QA of gas from the atmosphere treatment chamber to the purge chamber is: In FIG. 2, the leakage flow rate QAI from the atmosphere treatment chamber to the outside air is smaller than the leakage flow rate QAI from the atmosphere treatment chamber to the outside air when the pressure inside the atmosphere treatment chamber 1 is set higher than the outside pressure.

The gas that finally leaks from the purge chamber 5 to the outside air through the gap 7 between the elastic body 3 and the strip material 2 is either a mixture of a small amount of atmospheric gas and a purge gas, or a gas that is released into the atmosphere as a purge gas. By using a gas having a higher density than the gas, the amount of gas leaking from the purge chamber 5 to the outside air can be further reduced.

In other words, in general, when a fluid moves due to differential pressure, p=c・ρ・(Q/A )2...(14)
Therefore, if the differential pressure and flow path area are the same, the flow rate will be lower depending on the higher density.

In addition, in the present invention, when threading a sheet with low contact resistance, pressing is performed by applying the pressing force of the metal fittings 4.4 to the limit that does not cause creases on the strip material, and at the same time applying the pressing force of the metal fittings 4.4 to the extent that does not cause creases on the strip material. To minimize the leakage of expensive or dangerous atmospheric gas by adjusting the pressure of the purge chamber 5 and setting it as high as possible without affecting the atmosphere in the processing chamber. It is possible.

The purge gas may be any gas that is highly safe, or preferably one that is cheaper than the gas in the atmosphere treatment chamber and has a higher density. As is clear from equation (14), the higher the density ρ3 of the purge gas, the higher the gas density ρ in the purge chamber 5.
2 also increases, so if the differential pressure and gap area are the same, the leakage flow rate QB will be reduced.

In the present invention, the interrelationship between pressing force, contact resistance, purge chamber pressure P2, leakage gas flow rate QA, and Qe is determined in advance through experiments, etc., and the leakage flow rate QA to the purge chamber is adjusted using P2. I can do it. In other words, the purge chamber pressure is set based on the amount of atmospheric gas leaking from the atmosphere treatment chamber to the outside air and the formula (3) and C3 determined through preliminary experiments, and the minimum pressure necessary to secure the atmosphere inside the atmosphere treatment chamber is set. It is possible to adjust the leakage amount to

In addition, although the above explanation explained the example of the inlet and the outlet of an atmosphere processing chamber, the present invention may be applied to both the inlet and the outlet. Further, although the explanation has been given using the example of two stages of contact between the elastic bodies, low contact resistance and a reduction in the amount of atmospheric gas leakage can be achieved using the same logic when using three or more stages. However, the pressure in the purge chamber must be set so that it gradually decreases from the atmosphere treatment chamber to the outside air.

[Example] As an example of the present invention, a stainless steel strip having a thickness of 50 μm and a width of 370 mm was brightly annealed using the apparatus shown in FIG. 1 at the entrance of an atmosphere treatment chamber. The atmosphere in the furnace was a reducing atmosphere (8275%, N225%), and the pressure in the furnace was a cage pressure of 25 mm in water column. N2 scum was used as the scum for purging.

The tension applied to the strip with this device is 100g7mm2
Adjust the force when pressing the felt member so that it is as follows.
The contact resistance of the felt member was set to 200 g, and the pressure in the purge chamber 5 was set to a gauge pressure of 20 mm water column. Comparing the above strip with the conventional apparatus shown in FIG. 2 under the same furnace pressure, tension applied to the strip, and contact resistance of the felt member as in the present invention example, the present invention example has the same conditions as the furnace atmospheric gas. The amount of leakage to the outside air was reduced by about 40% compared to the comparative example, and no creases occurred in the strip. In addition, in the example of the present invention, by setting the pressure in the purge chamber as described above, it is possible to reduce the amount of leakage of gas in the furnace, and reduce the amount of leakage of atmosphere scum in the furnace during low contact resistance sheet passing. Safety was ensured by reducing the concentration of 02 near the sealing device by reducing the amount.

[Effects of the Invention] By using the sealing method of the present invention, it is possible to efficiently control the leakage of atmospheric gas even when the seal is opened and used to prevent the occurrence of creases in the strip material.
It is possible to reduce gas costs by preventing bending of the strip material due to low contact resistance and by reducing the amount of atmospheric debris leaking. In addition, for example, when the atmospheric gas has a danger of explosion, such as Ax gas, by diluting the Ax gas with purge gas, the concentration of the atmospheric gas leaking into the outside air is reduced, increasing safety. It is also possible to ensure that

Therefore, by using the sealing method of the present invention, it is possible to save the consumption of atmospheric gas without affecting the atmosphere in the atmosphere treatment chamber, not only during normal sheet passing but also during low contact resistance sheet passing. .

Furthermore, in the sealing method of the present invention, by installing a purge gas nozzle facing the strip-shaped material on the entrance side of the atmosphere treatment chamber, an effect of cleaning the surface of the strip-shaped material like an air shower can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention, and FIG.
3 and 3 are diagrams showing an example of a conventional apparatus for atmospheric treatment of a strip-shaped material. DESCRIPTION OF SYMBOLS 1... Atmosphere treatment chamber, 2... Strip material, 3... Elastic body, 3A... Felt member, 4... Hardware for pressing, 5... Purge chamber, 6... Nozzle , 7... Gap between light contact parts, 8... Roller, 9... Intermediate part, A, B-
...The direction of movement of the strip material.

Claims (1)

[Claims] 1. A plurality of elastic bodies that communicate with the inlet and/or outlet of the atmosphere treatment chamber of the strip-shaped material and lightly contact or approach both sides of the strip-shaped material are arranged in multiple stages at appropriate intervals along the traveling direction of the strip-shaped material. A sealing method for atmospheric treatment of a strip-shaped material, characterized in that the pressure between each of the plurality of stages of elastic bodies is set lower than the pressure of the atmosphere treatment chamber and higher than atmospheric pressure.