JPH0718340A - Contactless type sealing device for atmosphere furnace - Google Patents

Abstract

PURPOSE:To provide the contactless type sealing device which assures high sealability while decreasing the amt. of the sealing gases to be supplied and charged and suppresses an atmosphere change according to leakage of the sealing gases. CONSTITUTION:A gaseous atmosphere A equal to an atmosphere A is supplied from a supplying device 18a to the sealing gases to be discharged from the atmosphere A side nozzles 16a of the sealing unit 14a on the atmosphere A side among the laminated sealing units and the gaseous atmosphere B equal to an atmosphere B is supplied from a supplying device 18b to the sealing gases discharged from the nozzles 16b on the atmosphere B side of the sealing unit 14c on the atmosphere B side. The gases are properly exhausted from the other nozzles to prevent the leakage between the atmospheres A and B and to substantially prevent the generation of an atmosphere change even in the event of leakage of the sealing gases to the respective atmosphere A, B sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various atmospheric furnaces such as a carburizing furnace for controlling the atmosphere such as the atmosphere gas composition, composition gas concentration, furnace temperature, etc. in the vicinity of a metal strip to be threaded. , A non-contact type of atmosphere furnace that divides these atmospheres and discharges a seal gas toward at least the metal strip to individually control each divided atmosphere and thereby seals the adjacent atmospheres The present invention relates to a sealing device.

[0002]

2. Description of the Related Art In the metal secondary processing industry such as the automobile industry, it is required for a metal plate to be processed to have both high workability and strength. Specifically, in the automobile industry, it is necessary to reduce the weight of the car body in order to pursue low fuel consumption due to the global environmental problems that have recently become a problem. A steel sheet with higher strength is required while maintaining.

As an evaluation index of such a metal plate, for example, ductility, deep drawability, aging property, strength, secondary work brittleness, bake hardenability, spot weldability and the like are considered. Therefore, when the deep drawability is evaluated with a Rank Ford value (hereinafter r value: metal plate width strain / plate thickness strain) with particular emphasis on the deep drawability, carbon in steel (hereinafter referred to as C) It is known that it is most advantageous to reduce the amount, and in addition, ductility (Elongation: El) and normal temperature delayed aging (Aging Index: generally lower is better). On the other hand, on the other hand, as the amount of C in the steel decreases, the other evaluation indices largely deteriorate. For example, tensile strength (Tens
ile Strength: TS) decreases, the grain boundary strength decreases, secondary processing brittleness deteriorates, and the amount of solid solution C decreases, and bake hardenability deteriorates. Further, when the C content in the steel is 50 ppm or less, the grain growth rate is accelerated by heating by welding, and the spot-weldability deteriorates due to coarsening of the heat-affected zone (HAZ).

Therefore, as shown in FIG. 1, a metal strip made of an ultra-low carbon steel is recrystallized by a continuous annealing treatment to obtain the above-mentioned ductility, deep drawing property and aging property. By the presence of solid solution C in the surface layer by the treatment, the tensile strength, secondary work embrittlement, BH property,
In order to improve the spot weldability, the present applicant has developed a continuous annealing carburizing equipment described in JP-A-4-88126 as shown in FIG.

According to this continuous annealing carburizing equipment, the heating zone 2
Alternatively, after performing a predetermined recrystallization annealing on the metal strip in the soaking zone 3, the steel plate temperature, atmosphere specifications, transfer speed (in-furnace time), and the first and second cooling zones 5, 6 are used in the carburizing zone 4. By carrying out an appropriate carburizing treatment in which the cooling conditions are controlled by, it is possible to continuously produce a metal strip having desired surface carburizing depth and concentration distribution while satisfying the material specifications of the metal strip. For this metal strip, a strip in which steel plates having various material specifications are connected in series by welding or the like is often used.

In the carburizing furnace applied to the carburizing zone, there are many vertical type continuous gas carburizing furnaces in which strips to be threaded move up and down a plurality of paths in order to reduce the required floor area. The strip S, which is passed through the vertical continuous gas carburizing furnace so as to be folded back and forth, has its passing direction changed via the hearth roll 10 as shown in FIG. Specifically, if the strip is wound around almost half of the outer circumference of the hearth roll, the direction can be changed by 180 °.

In this hearth roll, a chromium Cr alloy is used in order to improve the mechanical strength under the use condition at high temperature. The hearth roll containing the Cr compound is carburized as described above. It has become clear that when it is exposed to atmospheric gas, it is carburized and its useful life is shortened. Therefore, this hearth roll is divided into a roll chamber separate from the heat treatment chamber for carrying out the carburizing treatment, and an appropriate sealing device is interposed between the heat treatment chamber and the roll chamber near the strip passage. ， It is necessary to control the atmosphere in both rooms individually. Specifically, the carburizing atmosphere in the carburizing heat treatment chamber is controlled to be a weak carburizing atmosphere or a non-carburizing atmosphere in the roll chamber so as not to promote carburizing into the hearth roll. Therefore, this sealing device must prevent the carburizing atmosphere gas in the heat treatment chamber from entering the roll chamber for that purpose. On the other hand, if the weakly carburized atmosphere gas or the non-carburized atmosphere gas enters the heat treatment chamber, a distribution of concentration composition occurs in the carburized atmosphere gas in the heat treatment chamber, which may cause unevenness in the carburization amount or the carburization concentration distribution. , Leakage in this direction must also be prevented.

Among such sealing devices, a typical contact type sealing device is one in which a rotating roll such as a pinch roll is directly rotated in contact with the strip.
Such contact-type sealing devices have defects such as flaws on the strip plate surface and thermal deformation. In addition, it is difficult to obtain a sufficient sealing property. Therefore, a non-contact type seal device has been proposed, which discharges the seal gas to the strip plate surface and seals between the two divided atmospheres by the static pressure of the seal gas generated between the strip gas surface and the strip surface. There is one described in Japanese Patent Laid-Open No. 2-259025.

The non-contact type seal device described in this publication is provided with two chambers, to which the divided atmospheric gas is supplied, on each of the front and back surfaces of the metal strip to be passed, and the metal is provided in the vicinity of each atmosphere. Two nozzles facing each other across the band are arranged respectively, and the nozzles in the vicinity of each atmosphere are connected to the chamber to which the atmospheric gas in the vicinity is supplied, and the neighboring atmospheric gas is sealed from each chamber to the nozzle in the vicinity of the atmosphere. It is supplied as gas. According to this non-contact type seal device, the seal gas discharged from each nozzle creates a static pressure between the sealant and the metal band to seal the two atmospheres, and the seal gas near the atmosphere leaks from the seal device ( Even if there is a leak, the change in the atmosphere can be suppressed.

[0010]

However, in some cases, even the above-mentioned non-contact type seal device may not be able to obtain a sufficient sealability, and there is still room for improvement. That is, since the non-contact type sealing device does not have a discharge port for the sealing gas charged in the sealing portion, the gas mixed in the sealing portion leaks into any of the divided atmospheres. as a result,
The atmosphere gas in the vicinity of the seal portion cannot be prevented from being diluted by the gas mixed in the seal portion or increasing the concentration of the atmosphere gas.

In this non-contact type sealing device for simply sealing the atmosphere defined by only the flow energy of the sealing gas discharged, two nozzles facing each other with a metal band sandwiched in the vicinity of each atmosphere are provided. Therefore, in order to prevent leakage between the two atmospheres, it is necessary to set the gap between the discharge nozzles facing each plate surface to some extent (if they are too close, the seal gases collide with each other and disturb each other. Flow occurs, and the seal gas and the atmospheric gas flowing into the vicinity leak into the other atmosphere), and thus the seal gas discharged from the discharge nozzles with wide intervals causes static pressure between the seal gas and the plate surface. In order to do so, it is necessary to increase the discharge amount (supply input amount) of the seal gas, which is not only wasteful but also increases the flow rate, the seal gas amount leaking to the other atmosphere increases. Further, in order to improve the sealing property, it is necessary to dispose the discharge nozzle close to the surface of the metal strip plate. However, the plate surface of the threaded metal strip may fluctuate due to meandering or the like, and when such fluctuation occurs, the plate surface comes into contact with the discharge nozzle arranged in the vicinity of the plate surface, and the flaw is damaged. There is also a problem that occurs.

The present invention has been developed in view of these problems, and secures a high sealing property while reducing the supply amount of the seal gas, thereby separating the discharge nozzle from the plate surface of the metal strip. It is an object of the present invention to provide a non-contact type sealing device for an atmospheric furnace that can avoid the occurrence of flaws due to fluctuations.

[0013]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and as a result, have obtained the following findings and developed the present invention. That is, in order to generate a static pressure of the seal gas between the metal strip plate surface and the metal strip plate surface by the discharged seal gas, on the contrary to the above, two discharges relatively close to each other along each plate surface are provided. It is well known that the sealing gas is discharged from the nozzles, and in particular, the directions of the sealing gas discharged from both nozzles may be inwardly opposed to the plate surface. However, if the non-contact type sealing device is composed of only these two discharge nozzles, the sealing distance between the divided atmospheres may be too short and may induce mutual leakage. Therefore, a seal structure composed of the two discharge nozzles facing inward is provided in the vicinity of each of the two divided atmospheres, and the intervals thereof are appropriately set. As necessary, the vicinity of the plate surface, the side of the metal strip, and both seal structures are provided. By exhausting the seal gas and the gas in the vicinity from the gap, the flow of the gas in the seal part is optimized, and the high sealing performance is exhibited with a small amount of the seal gas supplied and supplied. It was found that it can be separated from the plate surface. At this time, if the atmosphere gas in the vicinity of the discharge nozzle closest to the atmosphere is used as the seal gas, the change in the atmosphere due to the leak of the seal gas can be suppressed.

Thus, the non-contact type sealing device for an atmospheric furnace of the present invention is an atmospheric furnace for controlling the atmosphere around the metal strip to be passed, and divides the atmosphere and separates the divided atmospheres individually. In a non-contact type seal device of an atmosphere furnace that discharges a seal gas toward at least the metal strip and seals between adjacent atmospheres in order to control the above, the seal gas is a component perpendicular to the plate surface of the metal strip. Or a seal unit provided with a plurality of nozzles facing the metal strip plate surface for discharging the seal gas or gas in the vicinity thereof, and discharge of the seal gas from the nozzles, In order to simultaneously discharge the sealing gas or the gas in the vicinity from the nozzles, a plurality of layers are stacked along the plate surface of the metal strip, and at least the divided atmospheres of the plurality of nozzles are arranged. Care upcoming nozzle, it is characterized in that it comprises a supply means for supplying the atmosphere gas supplied to the atmosphere in the vicinity of the seal gas.

[0015]

In the non-contact type sealing device of the atmosphere furnace of the present invention,
From a plurality of nozzles formed by stacking a plurality of seal units along the plate surface of the metal strip and arranged in parallel along the plate surface facing each plate surface of the seal unit. The seal gas is discharged or the seal gas or the gas in the vicinity thereof is exhausted, and, for example, two adjacent nozzles near each atmosphere are inwardly opposed to the plate surface, and the seal gas is discharged from these inward facing nozzles. Thus, the flow of gas accompanying the movement of the plate can be stopped (the direction of the flow can be changed). Therefore, the interval between the two inward facing nozzles can be set appropriately, and, for example, the nozzle at the center of the sealing device can be used. The sealability between the two atmospheres is improved by discharging the seal gas or the atmosphere gas flowing into the vicinity of the seal gas. Each atmosphere last nozzle, it is possible to suppress a change in the atmosphere to supply the atmosphere gas supplied to the atmosphere in the vicinity of the seal gas, which is defined also if the sealing gas leaks.

[0016]

EXAMPLE FIG. 2 shows an example of continuous annealing carburizing equipment for strips made of ultra-low carbon steel, which uses the non-contact type sealing device for an atmospheric furnace of the present invention. In the same figure, each ultra low carbon steel sheet including steel sheets with different desired specifications,
A series of strips is formed by an unillustrated inlet side equipment having a coil rewinding machine, a welding machine, a washing machine, etc. The strip S is formed from the inlet side equipment in a pre-heat zone 1, a heating zone 2, a soaking zone 3, and a carburizing zone 4. , The first cooling zone 5, the second cooling zone 6, the shearing machine, the winding machine, and the like, which are not shown, are passed through in this order.

The heating zone 2 is for heating the strip S, which is continuously fed from the inlet side equipment and preheated in the preheat zone 1, to a temperature higher than the recrystallization temperature. Specifically, the temperature in the furnace is 850. The temperature of the strip S is 700 ~ 9 at ~ 1000 ° C.
Heat the strip to 50 ° C. Inside the heating zone 2 and the soaking zone 3 near the strip passage which is stripped up and down through a hearth roll,
A large number of radiant tubes (not shown) are provided, and the temperature of the furnace (furnace temperature) is controlled by burning the fuel gas fed to the radiant tubes.

The carburizing zone 4 is a carburizing furnace in the carburizing zone 4 700-950 by a host computer (not shown).
The temperature in the furnace (furnace temperature) is controlled to be 700 ° C. or more, preferably the recrystallization temperature or less, and the strip passes through the carburizing furnace in 10 to 120 seconds. The plate passing speed is controlled as follows. By the way, the furnace temperature control is performed in order to keep the carburizing amount (carburizing reaction rate) constant in the strip passing direction to suppress variations in materials.

The details of the continuous gas carburizing furnace used for the carburizing zone 4 are shown in FIG. As shown in the figure, the strip S fed from the soaking zone 3 once rises in the furnace, further falls, rises again, and then falls again before being sent to the first cooling zone 5. . Therefore, the continuous gas carburizing furnace of this embodiment has four passes, which are referred to as a first pass to a fourth pass in the order in which they are passed. Strip S between each pass
Is changed by the hearth rolls 10, so that the two hearth rolls 10 above the carburizing furnace and the three hearth rolls 10 below the carburizing furnace are arranged so that their axes are orthogonal to the strip passing direction of the strip S. It is installed in.

These hearth rolls 10 are made of a chromium-Cr alloy in order to improve their strength and wear resistance at high temperatures, and to maintain their rollability and roll crown in a prescribed state. Moreover, for example, the vicinity of the bearing and the like is cooled, but this causes a problem that the service life is reduced, which is due to the following causes. For example, when the carburizing atmosphere gas reaches the vicinity of the hearth roll and is cooled, sooting proceeds, so that C adheres to the hearth roll and then C diffuses inside the hearth roll.
In such a case, the Cr and C are combined to precipitate Cr carbide, which destroys or expands the crystal grains of the heat-resistant alloy used in the hearth roll, while the solid solution Cr is dissolved.
As a result, the hearth roll is embrittled and oxidized, so that hole-like corrosion progresses. When the hearth roll is exposed to the carburizing atmosphere gas as described above, experiments by the present inventors have revealed that the hearth roll must be replaced within one year.

Therefore, in this embodiment, the hearth roll chamber 12
Is separated from the carburizing atmosphere by a non-contact sealing device 11 to prevent deterioration of the hearth roll 10, and the inside of the hearth roll chamber 12 is set to a weak carburizing state to such an extent that deterioration of the hearth roll 10 does not proceed. Thus, it has succeeded in preventing so-called decarburization in which C is diffused from the carburized surface layer portion while the strip S passes through the separated hearth roll chamber 12. When the strip S passes through the hearth roll chamber 12 for a very short time and decarburization from the steel plate surface layer portion during the time is not a problem,
The inside of the hearth roll chamber 12 may be a non-carburizing atmosphere.

The non-contact type sealing device 11 has, for example, three layers of sealing units 14a to 14c in which a sealing layer interposed between a hearth roll chamber 12 and a carburizing atmosphere chamber (heat treatment chamber) 13 is unitized. The weak carburizing atmosphere gas is discharged as a seal gas to the seal unit 14a on the hearth roll chamber 12 side, and the carburizing atmosphere gas is discharged as a seal gas to the seal unit 14c on the carburizing atmosphere chamber side. The seal unit 14b of FIG. 2 is evacuated, and the discharge direction and discharge flow rate of the seal gas from each nozzle are controlled to control the flow of each seal gas, that is, the static pressure forming direction.
4B, and the circulation flow generated by the plate laminar flow accompanying the strip passage is exhausted from the side discharge port 17 formed in the widthwise end face of the strip of each seal unit. . These specific constituent features are essential to the present invention, and will be described in detail later.

A large number of radiant tubes 15 are arranged in the vicinity of the strip S through which each pass is passed. The radiant tube 15 controls the temperature inside the carburizing furnace (mainly heating and soaking control) by burning the fuel gas fed inside, and radiant heat from the surface of the tube. The amount is controlled by the feed amount of the combustion gas similarly to the heating zone 2 and the soaking zone 3, which is also importantly managed by the host computer (not shown) according to the control logic. In an industrial continuous carburizing operation, in order to stably achieve desired metal strip specifications with a limited effective carburizing length (carburizing time), the carburizing atmosphere gas composition in the carburizing furnace, particularly in the heat treatment chamber, It is essential to make the atmosphere uniform, such as gas composition concentration and carburizing temperature.

The strip S delivered from this carburizing zone 4
Is fed to the first cooling zone 5. In the first cooling zone 5, the solid solution C is fixed only in an extremely thin area on the surface of the strip surface layer, so that the steel sheet after carburizing has a steel sheet temperature of 600 ° C. or less, preferably about 500 to 400 ° C. Up to 20 ° C / sec. Or faster. In order to achieve this cooling condition in the first cooling zone 5, the flow rate, flow velocity and cooling roll of the sprayed cooling gas blown from the cooling gas jet to the strip conveyed in the cooling zone by the host computer. The temperature, winding angle, etc. are controlled.

The strip S delivered from the first cooling zone 5 is then delivered to the second cooling zone 6. In the second cooling zone 6, gas cooling is performed up to a steel plate temperature of about 250 to 200 ° C. In this way, an extremely low carbon cold-rolled steel sheet for press forming can be finally obtained in which solid solution C exists only in the surface layer portion. Next, each component required for the above-mentioned non-contact type seal device will be described based on an experiment actually performed.

First, the non-contact type seal device of this embodiment is
It was developed to achieve the following purposes, as well as to enhance its sealing property. As described above, when the carburizing atmosphere gas in the heat treatment chamber leaks into the hearth roll chamber, damage to the hearth roll occurs or is accelerated. On the other hand, if the weak carburizing atmosphere gas or the non-carburizing atmosphere gas in the hearth roll chamber leaks into the heat treatment chamber, a concentration distribution occurs in the carburizing atmosphere, and the carburizing amount varies in the strip width direction or the strip passing direction. This phenomenon becomes more remarkable when the industrial continuous carburizing operation as described above is performed. Therefore, in this non-contact type sealing device, it is necessary to suppress the mutual leakage of atmospheric gas between the divided atmospheres as much as possible. At the same time, it is necessary to prevent the seal gas from leaking to each atmosphere side as much as possible, but it is also possible that the flow of the seal gas may be disturbed by fluctuations in the plate surface, which will be described later.In such a case, the seal gas leaks. Is hard to avoid. However, even if the seal gas leaks to each atmosphere side, at least the change in the atmosphere should be prevented. Further, the plate surface of the strip may fluctuate due to meandering or the like, and if the plate surface comes into contact with a seal gas discharge nozzle or an exhaust nozzle due to the fluctuation of the plate surface, a flaw may occur. Therefore, at least each nozzle needs to be separated from the strip plate surface as much as possible. Furthermore, in order to make the effective carburizing furnace length of the carburizing zone as long as possible, it is necessary to collect each seal length within a predetermined range. Of course, from the viewpoint of energy saving, it is preferable that the amount of the seal gas discharged, that is, the amount of the seal gas supplied is small.

Therefore, in this embodiment, as shown in FIG. 4, a plurality of nozzles 16a and 16b facing each plate surface are provided, and a lateral exhaust port 17 is provided laterally in the width direction of the strip S so that the seal unit 14a.about. 14c, one or more of the seal units 14a to 14c are laminated along the plate surface of the strip S, and discharge of the seal gas from the nozzles 16a and 16b and the seal gas generated by the nozzles 16a and 16b and The following parameters were changed so that the gas in the vicinity could be discharged at the same time, and the sealing property between the atmospheres in the chambers A and B shown in the figure was examined.

Specifically, each seal unit 14a-14
c, the strip S is sandwiched between the strip c and the strip S.
Slit-shaped nozzles 16a, 16b extending in the width direction of the
Are arranged side by side along the plate surface of the strip S. For convenience, A in each of the seal units 14a to 14c
The nozzle on the chamber side is referred to as nozzle 16a, and the nozzle on the chamber B side is referred to as nozzle 16b. In addition, these nozzles 16a, 1
6b is configured such that a properly selected seal gas can be input and discharged, or the seal gas and the gas in the vicinity can be sucked and exhausted. Furthermore, the seal gas discharge angles of the discharge nozzles can be changed in the directions in which the adjacent nozzles face each other in the unit. Also,
The side exhaust port 17 of each unit can switch between exhaust, shutoff, and discharge as required. Further, the atmosphere in the chamber A was made to be a hearth roll chamber and its atmosphere was made equal to that of air, and the chamber in the chamber B was made to be a heat treatment chamber, and a mixed gas of nitrogen N ₂ and helium He was introduced. In addition, the evaluation method of the sealability includes the flow state of each atmosphere gas, the oxygen O ₂ concentration in each chamber, the discharge flow rate of the seal gas (the smaller the better), and the exhaust flow rate from each chamber (the larger the better). The flow state of each atmosphere gas was evaluated by taking the strip passing plate into consideration.

Next, among the above parameters, the seal gas discharge / exhaust pattern for each nozzle will be described.
For example, when the seal unit has a three-layer laminated structure as shown in FIGS. 3 to 4, this seal gas discharge / exhaust pattern is discharged from the nozzles 16a and 16b facing each other across the strip S in FIG. Alternatively, either ₂ π ₆ = 64 ways, 16 ways in the case of two seal unit layers, and four ways in the case of one seal unit layer (single layer) can be considered. Further, whether or not exhaust is performed from the side exhaust port is also added to this. Regarding the discharge / exhaust state of the seal gas from each nozzle and the side exhaust port, refer to FIG. 4 as a legend.

Next, since the discharge angle of the seal gas can be an important parameter for the air flow generated in the seal device as described above, the seal gas discharge angle θ is arranged in parallel with each other as shown in FIG. The experiment was conducted by changing the nozzles 16a and 16b in the opposite direction. In addition, each ejection angle θ is
The strip surfaces are changed so as to face each other inward, and the set discharge angles of the nozzles 16a and 16b do not have to be the same.

Next, in accordance with the discharge angle of the seal gas, the seal gas discharge flow rate ratio of each nozzle can be an important parameter for the air flow generated in the seal device. This is because in each seal unit, for example, as shown in FIG. 6, the gas flow rate α of the nozzle 16a on the side where leakage is not desired.
And the gas flow rate β of the nozzle 16b that may leak. That is, it means α / β in the figure,
In the experiment, the nozzle discharge flow rate α on the side that you do not want to leak,
The nozzle discharge flow rate β on the side that may leak is changed under the condition of α ≧ β.

Next, an air atmosphere side as shown in FIG. 7 the composition of the sealing gas, i.e. ejecting air from the A chamber side of the nozzle 16a, N ₂ atmosphere side, namely B chamber side of the nozzle 16
b when N ₂ is discharged from all nozzles 16a, 1
A comparison is made when N ₂ is discharged from 6b. According to this experiment, by using the seal gas having the same composition as the atmosphere in the discharge nozzle on the sealing side, that is, the nozzle closest to the atmosphere, it is determined whether or not the atmosphere composition can be expected to be maintained even if a leak occurs. It

Next, as described above, as shown in FIG. 9, a circulating flow of the seal gas is generated laterally in the width direction of the strip S, and this circulating flow may induce a leak of the sealing gas or the atmospheric gas. There is. Therefore, the exhaust is performed from the side exhaust port 17 provided in each of the seal units 14a to 14c. The ratio of the exhaust amount from the side exhaust port to the exhaust amount from the exhaust nozzle is changed to change the amount of the seal gas. The leak reduction effect was tested.

From the above experimental results, in the seal gas discharge / exhaust pattern, the effect of good sealability was obtained in the following two patterns. Pattern 1: A room side and B room side seal unit 14
The seal gas is discharged from all the nozzles 16a and 16b of a and 14c, the exhaust is performed from all the nozzles 16a and 16b of the central seal unit 14b, and the seal unit 14a and 14c side of the A chamber side and the B chamber side is discharged. Exhaust from the exhaust port 17 only.

Pattern 2: Seal unit 14 on the room A side
Of a, the seal gas is discharged from the B chamber side nozzle 16b and exhausted from the A chamber side nozzle 16a, and the A chamber side nozzle 16a of the B chamber side seal unit 14c is discharged.
From the nozzle 16b on the chamber B side, exhausts the seal gas from all the nozzles 16a, 16b of the central seal unit 14b, and exhausts the side gas from the central seal unit 14b. Exhaust only from.

As described above, when the side exhaust was performed from the side exhaust port in the vicinity of the discharge nozzle, excellent sealing was exhibited. Further, FIG. 9 shows the result of investigation on the influence of the discharge angle of the seal gas on the sealing property. In this experiment, as shown in the figure, all the nozzles 16a and 16b of the seal units 14a and 14c on the chamber A side and the chamber B side are exhausted, and all the nozzles 1 of the seal unit 14b at the center are discharged.
The seal gas is discharged from 6a and 16b, and the discharge angle of the seal gas is θ = 90 ° (straight) shown in FIG.
And the case of θ = 45 °, the O ₂ concentration in each room was detected. N ₂ gas was used as the seal gas, the total amount of the seal gas was aNl / min, and the seal exhaust flow rate was changed. As is clear from the figure, when the seal exhaust gas flow rate is increased, the discharge angle of the seal gas is θ = 45 ° compared to the case of θ = 90 °, that is, the seal gas is discharged inward with respect to the plate surface of the metal strip. It can be seen that the sealing property is significantly improved by making it face-to-face and diagonal.

Next, FIG. 10 shows the result of investigation on the influence of the amount of the seal gas and the amount of the exhaust gas on the sealing property. In this experiment, as shown in the figure, all the nozzles 16a, 16b of the seal units 14a, 14c on the A chamber side and the B chamber side were exhausted, and the seal gas of all the nozzles 16a, 16b of the central seal unit 14b was sealed. The discharge was performed, and the discharge angle of the seal gas was set to θ = 45 °. Under this condition, the total amount of seal gas input is bNl / min
And the case of cNl / min (where c = 3.5b), the O ₂ concentration in each chamber was detected when the flow rate of the seal exhaust gas was changed. N ₂ gas was used as the seal gas. As is apparent from the figure, when the injection amount of the seal gas is increased, the sealing performance is improved by exhausting an amount corresponding to the increase. Also,
It was found that this seal gas discharge / exhaust pattern functions as a seal by satisfying the condition of exhaust amount ≧ seal gas input amount.

Next, FIG. 11 shows the result of investigation on the influence of the nozzle flow rate ratio on the sealing property. In this experiment, as shown in the figure, the seal units 14a on the A chamber side and the B chamber side,
The seal gas was discharged from all the nozzles 16a and 16b of 14c, the gas was discharged from all the nozzles 16a and 16b of the central seal unit 14b, and the discharge angle of the seal gas was set to θ = 60 °. . Under this condition, the total amount of the seal gas charged is d based on the knowledge of FIG.
In the case of Nl / min and total exhaust amount eNl / min (where d <e), the O ₂ concentration in each chamber was detected when the nozzle flow rate ratio was changed. In this case, each room side is shown in FIG.
In the seal unit 14a on the A-chamber side, the discharge flow rate of the nozzle 16a on the A-chamber side is α, and that on the B-chamber side is α. Let β be the discharge flow rate of the nozzle 16b, α be the discharge flow rate of the B chamber side nozzle 16b in the B chamber side seal unit 14c, and be β be the discharge flow rate of the A chamber side nozzle 16a. And As is clear from the figure, the nozzle flow rate ratio α / β is increased, that is, the seal gas discharge flow rate α of the nozzle on the partitioned chamber side is
It can be seen that the sealability is improved by increasing the flow rate β of the seal gas discharged from the adjacent nozzles relatively.

Next, FIG. 12 shows the result of investigation on the influence of the seal gas composition on the sealing property. In this experiment, as shown in FIG.
Air is discharged from the nozzle 16a on the chamber side, and the adjacent nozzle 1
N ₂ gas is discharged from 6b, and the seal unit 1 on the B chamber side
N ₂ gas is discharged from all nozzles 16a and 16b of 4c, and all nozzles 16 of the central seal unit 14b
Evacuation was performed from a and 16b, and the discharge angle of the seal gas was set to θ = 60 °. Under this condition, as in the case of FIG. 11, the total injection amount of the seal gas is fNl / min.
In the case of the total exhaust amount gNl / min (where f <g), the O ₂ concentration in each chamber when the nozzle flow rate ratio was changed was detected. Also in this case, assuming that each chamber side corresponds to the direction in which leakage is not desired in FIG. 6 and the central seal unit side corresponds to the direction in which leakage may occur, the A chamber side seal unit 14a corresponds to the A chamber side nozzle. The discharge flow rate of 16a is α, and the discharge flow rate of the nozzle 16b on the B chamber side is β.
In the chamber side seal unit 14c, the B chamber side nozzle 16b
Of the nozzle 16a on the chamber A side is β
And this α / β is the nozzle flow rate ratio. As is clear from the figure, a gas having the same composition as the atmosphere in the room is discharged from the partitioned nozzle on the chamber side, and the nozzle flow rate ratio α / β is increased, that is, the nozzle on the partitioned chamber side is sealed. It can be seen that the sealing performance is dramatically improved by increasing the gas discharge flow rate α relatively to the discharge flow rate β of the adjacent nozzle.

As described above, the sealing device is constructed by stacking two or more sealing units each having the discharge nozzle and the exhaust nozzle and provided with the side exhaust port, of which the side exhaust port near the discharge nozzle is located side by side. Higher sealing performance can be secured by exhausting air in one direction. Also, when discharging from the adjacent nozzles in each seal unit,
The angles of discharge of the seal gas are made to incline so as to face the strip plate surface inwardly, and the flow rate of the discharge of the divided atmosphere side is made relatively large so that the air flow of the seal gas is generated. By stopping the flow of gas flowing along the surface and disposing the exhaust nozzle at the tip of this gas flow, the sealing performance is improved. Further, if the total exhaust amount in the sealing device is not more than the total amount of the sealing gas input, this type of non-contact type sealing device does not function sufficiently. Further, by discharging the atmosphere gas as a seal gas from the nozzle closest to the atmosphere, it is possible to suppress the change in the atmosphere.

From these experimental results, one ideal structure of the non-contact type sealing device is shown in FIG. This non-contact type seal device is a three-layer seal unit 14a, 14b, 14c.
Of which the seal gas is discharged from all the nozzles 16a and 16b of the seal unit 14a on the atmosphere A side, and the side exhaust port 17 exhausts or shuts off as needed, and the atmosphere B side. Seal unit 14
The seal gas is discharged from all the nozzles 16a and 16b of c, and the side exhaust port 17 exhausts or shuts off as needed, and all the nozzles 16 of the central seal unit 14b
The air is exhausted from a and 16b, and the side exhaust port 17 is shut off or exhausted as needed. Then, as described in the present invention, the seal unit 14a on the atmosphere A side is
The discharge angles of the nozzles 16a and 16b on the respective plate surfaces are set to face each other inward, and the flow rate ratio α / β of both is set to 2 to 4, and the sealing unit 14 on the atmosphere B side is set.
The discharge angles of the nozzles 16a and 16b on the plate surface side of c are set to face each other inward, and the flow rate ratio α / β of both is set to 2 to 4. Then, the same atmosphere A gas as the atmosphere A is supplied as the seal gas from the atmosphere A gas supply source to the nozzle 16a on the atmosphere A side of the seal unit 14a on the atmosphere A side by the supply device 18a, and the nozzle 16b on the atmosphere B side is supplied. Atmosphere A or B or C different from them
Gas is supplied as a seal gas. On the other hand, to the nozzle 16b on the atmosphere B side of the seal unit 14c on the atmosphere B side, the same atmosphere B gas as the atmosphere B is supplied as a seal gas from the atmosphere B gas supply source by the supply device 18, and the nozzle 16a on the atmosphere A side is supplied. Atmosphere B or A or C gas different from them is supplied as a seal gas. This non-contact type seal device optimizes the gas flow in the seal part with a small amount of supply of the seal gas, and at the same time enhances the exhaust efficiency to suppress the leak between atmospheres and suppress the disturbance of each atmosphere due to the seal gas leak. be able to.

In the present embodiment, the detailed description has been made only on the case of continuously annealing and carburizing a strip made of extremely low carbon steel, but the non-contact type sealing device of the atmosphere furnace of the present invention is not limited to the carburizing furnace, and is not limited to the carburizing furnace. It goes without saying that it can be applied to a seal between compartments. Further, although the sealing device of the present invention has been described by taking the vertical furnace as an example, it can be applied to a horizontal furnace.

The nozzles facing inward do not necessarily have to be in the immediate vicinity of the divided atmosphere.
It should be close to each atmosphere, but in that case,
It is necessary to consider that the leak of the seal gas should be avoided as much as possible by exhausting from the nozzle closer to the atmosphere. Further, the composition of the discharge gas supplied with the atmosphere gas as a seal gas does not necessarily have to be a nozzle having the same composition as the divided atmosphere, and may be a composition in the vicinity of each atmosphere, in which case However, it is necessary to consider how to avoid leak of the seal gas as much as possible by exhausting air from the nozzle closer to the atmosphere.

[0044]

As described above, according to the non-contact type sealing device for an atmospheric furnace of the present invention, a plurality of nozzles arranged in parallel facing each plate surface of the metal strips of a plurality of laminated seal units are used. By discharging the seal gas or exhausting the seal gas or the gas in the vicinity thereof, an optimal gas flow is formed between the plate surface and the atmosphere with a relatively small amount of supply of the seal gas. In addition to improving the performance, the sealed gas discharge nozzles in the immediate vicinity of each divided atmosphere supply the atmospheric gas that is supplied to the nearby atmosphere as a seal gas. Can be suppressed. Therefore, in the non-contact type sealing device for an atmospheric furnace of the present invention capable of ensuring such a high sealing property, for example, by widening the distance between the plate surface of the metal strip to be threaded and the nozzle facing the plate, It is possible to prevent the occurrence of flaws due to the fluctuation of the surface.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory view of a heat treatment process performed in a continuous annealing carburizing facility.

FIG. 2 is a schematic configuration diagram showing an example of a continuous annealing carburizing equipment using a non-contact type sealing device for an atmospheric furnace of the present invention.

FIG. 3 shows a continuous gas carburizing furnace used in the continuous annealing carburizing equipment of FIG. 2, (a) is a vertical sectional front view,
(B) is a vertical cross-sectional side view.

FIG. 4 is a schematic configuration diagram showing an example of a non-contact type sealing device used in the carburizing furnace of FIG.

5 is an explanatory view of a discharge angle of a seal gas in the non-contact type seal device of FIG.

6 is an explanatory diagram of a flow rate of a seal gas from each nozzle in the non-contact type seal device of FIG.

FIG. 7 is an explanatory diagram of composition change of seal gas from each nozzle in the non-contact type seal device of FIG.

8 is an explanatory diagram of a circulation flow and lateral exhaust that are generated laterally in the strip width direction in the non-contact type sealing device of FIG.

9 is an explanatory diagram of a result of an experiment of sealing property performed by changing the discharge angle of the seal gas in the non-contact type sealing device of FIG.

FIG. 10 is an explanatory diagram of a result of an experiment on sealing property performed by changing the discharge flow rate (total input amount) of the seal gas and the exhaust flow rate in the non-contact type seal device of FIG.

FIG. 11 is an explanatory diagram of a result of an experiment of sealing property performed by changing the flow rate ratio of the seal gas discharge nozzle in the non-contact type seal device of FIG.

FIG. 12 is an explanatory diagram of a result of an experiment on the sealing property performed by changing the composition of the sealing gas and the flow rate ratio of the discharge nozzle in the non-contact type sealing device of FIG.

FIG. 13 is a detailed explanatory view of a seal gas discharge / exhaust structure of the non-contact seal device adopted in this embodiment.

[Explanation of symbols]

 1 is pre-tropical zone 2 is heating zone 3 is soaking zone 4 is carburizing zone 5 is first cooling zone 6 is second cooling zone 10 is hearth roll 11 is sealing device 12 is hearth roll chamber 13 is heat treatment chamber 14a to 14c is seal Unit 15 is a radiant tube 16a, 16b is a nozzle 17 is a side exhaust port 18a, 18b is a supply device S is a strip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Kuramoto, Inventor 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (no address) Inside the Mizushima Steel Works, Kawasaki Steel Co., Ltd. (72) Nobuaki Hanazono, Kawashima-dori, Kurashiki City, Okayama Prefecture 1 Chome (No house number) Kawasaki Steel Co., Ltd. Mizushima Steel Works

Claims (1)

[Claims] 1. An atmosphere furnace for controlling an atmosphere around a metal strip to be threaded, wherein at least the metal strip is sealed in order to divide the atmosphere and individually control each of the divided atmospheres. In a non-contact type seal device of an atmosphere furnace that discharges gas to seal between adjacent atmospheres, the seal gas is discharged in a direction having a component perpendicular to the plate surface of the metal strip, or the seal gas Or, in order to discharge the gas in the vicinity thereof, a seal unit provided with a plurality of nozzles facing the metal strip plate, discharge of the seal gas from the nozzle, and discharge of the seal gas from the nozzle or the gas in the vicinity As is performed at the same time, a plurality of layers are stacked along the plate surface of the metal strip, and among the plurality of nozzles, at least the nozzles closest to each atmosphere are supplied to the atmosphere in the vicinity. A non-contact type seal device for an atmosphere furnace, comprising a supply means for supplying an atmosphere gas as a seal gas.