JPH11236623A - Continuously reducing atmospheric annealing apparatus for metallic strip and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable continuous annealing in the reducing atmosphere to a metallic strip even in the case of being the thin strip thickness. SOLUTION: At the time of passing a thick gage strip through annealing apparatus shown in the figure (a), the atmospheric gas used for cooling of the metallic strip 21 in a cooling zone 24 after annealing, is circulated into a preheating zone 26 and the energy consumption is saved and the times needed to the heating-up and the cooling of the metallic strip 21 are shortened and the productivity is improved. At the time of passing the thin gage strip through the annealing apparatus shown in the figure (b), only the cooling of the metallic strip 21 in the cooling zone 24, is executed by circulating the atmospheric gas raising the temp. with a heater 23. The slow cooling, avoiding the rapid cooling the metallic strip 21, is executed to prevent the development of fold, etc. The atmospheric gases in a high temp. route 29 and a low temp. route 30 are circulated by connecting with an atmospheric gas circulating system 22, and the moisture is absorbed in a refining device and dispersed to the atmosphere. Even in the case of changing over to the thick gage strip after passing the thin gage strip, since the atmospheric gas supplied into the preheating zone 26 does not absorb the moisture, the defective coloring can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous reducing atmosphere annealing apparatus for a metal strip and a method for continuously annealing a metal strip in a reducing atmosphere at a stage of manufacturing a metal material.

[0002]

2. Description of the Related Art Conventionally, a metal strip such as iron that has been cold-rolled is generally subjected to an annealing treatment and then moved to the next step. When the metal band is made of stainless steel or the like and the metallic luster of the material surface is regarded as important, bright annealing, also abbreviated as BA, is performed. As prior art relating to continuous annealing of a metal strip such as stainless steel under a reducing atmosphere, the present applicant has disclosed Japanese Patent Application Laid-Open No. 61-250117 (Japanese Patent Publication No. 5-1377).
3) and Japanese Patent Application Laid-Open No. 62-290830.

FIG. 4 shows the structure of the vertical continuous annealing apparatus for metal strips shown in FIG. 1 of Japanese Patent Publication No. 5-14733. The metal strip 1 as a metal strip is supplied upward, the sheet passing direction is reversed by the top roll 2, and thereafter, it enters the annealing furnace 3 where it is heated and further cooled by the plurality of cooling devices 4. In the cooling device 4, the metal strip 1 is cooled by blowing a reducing atmosphere gas thereon, and the atmosphere gas heated by removing heat from the sprayed metal strip 1 is collected by the high-temperature blower 5 and supplied upward. Then, it is supplied to the preheating device 6 for the metal strip 1. The preheating device 6 converts the supplied atmospheric gas into the metal strip 1.
To preheat the metal strip 1 and cool the atmospheric gas. The atmospheric gas used for preheating is collected by the low-temperature blower 7 and returned to the cooling device 4 ′, which is arranged on the upstream side near the annealing furnace 3 among the plurality of cooling devices 4. As described above, the atmospheric gas is circulated and used between the cooling device 4 ′ and the preheating device 6, and is directly collected by the cooling device 4 on the downstream side, cooled by the cooler 8, and cooled by the blower 9. The circulation returned to 4 is also performed. The ambient gas returned from the low-temperature blower 7 to the cooling device 4 ′ is also cooled by the cooler 10. The metal strip 1 is supplied by being sealed by an inlet seal 12 provided at the entrance of the entrance chute 11 so as to prevent the surrounding air from entering, and after being cooled, the metal strip 1 is sealed by the outlet seal 13 so as not to allow the air to enter. It is taken out in the state.

In Japanese Patent Publication No. 5-14773, the cooling device 4 '
Atmosphere gas is circulated between the metal strip 1 and the preheating device 6 to preheat the metal strip 1 to reduce the heating energy and time required for annealing the metal strip 1 in the annealing furnace 3,
When the atmospheric gas is cooled when the metal strip 1 is preheated, an energy saving effect that the cooling amount required in the cooler 10 can be reduced can be obtained. Further, since the time required for heating and cooling is shortened, it is possible to increase the passing speed of the metal strip 1 to improve the production efficiency, and to reduce the height of the apparatus to reduce the equipment cost. Become.

[0005]

In a vertical continuous annealing apparatus for a metal strip as shown in FIG.
Although a desired effect can be obtained when a thick gauge is passed through a relatively thick gauge, when a thin gauge is passed through a relatively thin plate, the atmospheric gas cooled by the cooling device 4 ′ is blown to blow the thin gauge. Metal strip 1 is quenched,
There is a problem that wrinkles occur. For this reason, when the thin gauge material is passed, gentle cooling is performed by blowing an atmosphere gas heated by a heater or the like to prevent wrinkles.

When slow cooling is performed, the circulation system of the atmospheric gas to the preheating device 6 for preheating the metal strip 1 is closed. When the thick gauge material is passed next to the thin gauge material as the metal strip 1, the use of the ambient gas circulation system is restarted to use the preheating device 6 again. Atmosphere gas stays in the closed circulation system, and when preheating is resumed, the atmosphere gas stayed in the circulation system is sprayed on the surface of the metal strip 1. Atmosphere gas staying at one location gradually absorbs moisture, so when the staying atmosphere gas is sprayed on the metal strip 1, moisture adheres to the surface of the metal strip 1 and coloring occurs. A phenomenon called a temper color easily occurs. For this reason, when the metal strip 1 is switched from the thin gauge material to the thick gauge material, the yield decreases, or in order to avoid the decrease in the yield, the preheating is gradually started, and the threading cannot be performed during that time.
There is a problem that production efficiency must be reduced.

An object of the present invention is to provide a continuous reducing atmosphere annealing apparatus and method for a metal strip which does not cause coloring of the metal strip even when switching from a thin gauge material that does not perform preheating to a thick gauge material that performs preheating. It is to be.

[0008]

According to the present invention, there is provided a pre-tropical zone for blowing a reducing atmosphere gas to a preheating by blowing an reducing atmosphere gas to an entrance chute for passing a metal strip upward, and the top of the entrance chute is inverted. A continuous metal band having a heating zone for performing heating for annealing treatment on a metal band that is passed downward and passed through a plate, and a cooling zone for cooling by blowing a reducing atmosphere gas onto the annealed metal band. In the reducing atmosphere annealing device, the atmosphere gas formed between the cooling zone and the pre-tropical zone and used for cooling the metal zone from the cooling zone is recovered and supplied to the pre-tropical zone, and the pre-tropical zone is used for preheating the metal zone. A circulation path including a refining device that circulates the atmosphere gas and adsorbs moisture so that the used atmosphere gas is collected and supplied to the cooling zone, and the atmosphere gas used for cooling the metal band from the cooling zone. Collect and raise the temperature A temperature rising path for returning to the cooling zone, and a switching valve group for switching and using the circulation path and the temperature rising path according to the thickness of the metal band so that the temperature of the cooling zone is adapted to the thickness of the metal band. And a continuous reducing atmosphere annealing apparatus for a metal strip.

According to the present invention, the inlet chute is provided with a pre-tropical zone for preheating by blowing a reducing atmosphere gas onto the metal strip to be passed upward. For metal strips that are inverted at the top of the entry chute and passed down,
A heating zone for performing an annealing process and a cooling zone for cooling by blowing a reducing atmosphere gas to the annealed metal zone are provided.
A circulation path of atmospheric gas is formed between the cooling zone and the pre-tropical zone, and the atmospheric gas used for cooling the metal zone is collected from the cooling zone and supplied to the pre-tropical zone, and the pre-tropical zone is used for preheating the metal zone. The used atmosphere gas is recovered and supplied to a cooling zone. The heating path collects the atmospheric gas used for cooling the metal strip from the cooling zone, raises the temperature, and returns the gas to the cooling zone. The switching valve group switches between the circulation path and the heating path in accordance with the thickness of the metal strip, and sets the temperature of the cooling zone to a temperature suitable for the thickness of the metal strip. For example, when the thickness gauge is passed, the temperature rising path is stopped and the atmospheric gas is circulated between the pre-tropical zone and the cooling zone, so that pre-heating and cooling can be performed efficiently, and an energy saving effect can be obtained. At the time of thin gauge threading, stop preheating by pre-tropics,
Since the temperature of the atmosphere gas recovered from the cooling zone is raised by the heating path and returned to the cooling zone, the metal zone after annealing can be slowly cooled without being rapidly cooled, and wrinkles can be prevented. . Atmosphere gas in the circulation path, except for the cooling zone and the pre-tropical zone, is circulated to the refining device for adsorbing moisture provided in the atmosphere gas circulation system, and the adsorbed moisture is diffused into the atmosphere. Water absorption can be prevented. As described above, when the atmosphere gas circulating even when passing through the thin gauge is switched to the thick gauge passing, it is supplied to the pre-tropical zone and is sprayed on the surface of the metal strip to preheat, so that the surface of the metal strip is colored. It is possible to quickly switch from thin gauge passing to thick gauge passing.

Further, in the present invention, the circulation path connects the high-temperature side path from the cooling zone to the pre-tropical zone, the low-temperature side path from the pre-tropical zone to the cooling zone, and connects the high-temperature side path and the low-temperature side path. A switching path group forming a partial circulation system, wherein the switching valve group includes a preheating switching valve provided on a high-temperature side path and a low-temperature side path, and a connection switching valve provided near each inlet of the connection path. And characterized by the following.

According to the present invention, as the circulation path, the high-temperature side path from the cooling zone to the pre-tropical zone, the low-temperature side path from the pre-tropical zone to the cooling zone, and the high-temperature side path and the low-temperature side path are partially connected. And a connection path that forms a simple circulatory system. The switching valve group includes a switching valve for preheating provided in the cooling zone and the pre-tropical zone, and a switching valve for connection provided near each inlet of the connection path. Atmospheric gas is circulated between the cooling zone and the pre-tropical zone using the route. When the thin gauge is passed, the high-temperature side path and the low-temperature side path are connected to the connection pipe, and circulation of the atmospheric gas is performed in a state where the cooling zone and the pre-tropical zone are separated. When switching from the thin gauge material to the thick gauge material, the atmospheric gas in the high-temperature side path and the low-temperature side path is circulated to the refining device provided in the atmospheric gas circulation system for adsorbing moisture, and the adsorbed moisture is removed. Is switched in a state of being released to the atmosphere, so that it is possible to prevent a situation in which coloring occurs even when an atmospheric gas is sprayed on the surface of the metal strip in the pre-tropical zone.

Further, the present invention provides a method in which a metal strip is supplied while being passed upward in a reducing atmosphere, the passing direction is reversed at the top, and the metal strip which is passed downward is heated and annealed. In a continuous reducing atmosphere annealing method for a metal strip, in which a reducing atmosphere gas is blown to cool, a refining device that adsorbs moisture is provided between a portion in which a passing direction of the metal strip is directed upward and a portion directed downward. A circulation path for the reducing atmosphere gas is formed in advance, and when the metal strip is passed through a thick gauge,
Using the circulation path, collect the atmosphere gas that has cooled the annealed metal strip, spray it onto the metal strip that is passed upward and preheat it, and collect the atmosphere gas that has preheated the metal strip and turn it downward. Circulation is performed by spraying and cooling the annealed metal strip to be passed through, and when the metal strip is thin and thin gauge passing, the atmosphere gas that has cooled the annealed metal strip is collected and heated to increase the metal strip. A continuous reducing atmosphere annealing method for metal strips, characterized by circulating the atmosphere gas in the circulation path without spraying on the metal strip passing upward while circulating so as to spray the cooling of the metal strip. is there.

According to the present invention, the metal strip passed downward in the reducing atmosphere is heated and annealed, and when the reducing strip gas is blown and cooled to perform the annealing, the metal strip is heated. At the time of thick gauge gauge passing, utilizing the circulation path formed between the upward and downward portions of the metal strip passing direction,
Atmosphere gas, which has cooled the annealed metal strip, is blown upward to the metal strip that is passed upward to preheat, and the atmosphere gas used for preheating is blown down to the annealed metal strip that is passed downward to cool. Circulate as you do. The heat obtained by cooling the metal strip after annealing is used for preheating, and the metal strip after annealing is cooled using an atmosphere gas that is cooled from the metal strip side by preheating, so energy efficiency in preheating and cooling Can be increased. Preheating is stopped when thin gauges are passed, and the ambient gas used for cooling is circulated so as to raise the temperature and spray it onto the metal strip to cool it down. Can be prevented. Since the atmosphere gas in the circulation path is circulated in the circulation path, the atmosphere gas circulated in the circulation path is used for preheating when switching from thin gauge material passing to thick gauge material passing. . The atmosphere gas does not stay even when the thin gauge is passed, so that there is no absorption of moisture, and the coloring of the metal band can be prevented.

[0014]

FIG. 1 shows a schematic operating state of a continuous annealing apparatus 20 according to an embodiment of the present invention. FIG. 1A shows a state in which the metal strip 21 is thicker than a predetermined thickness when the gauge is passed, and FIG. 1B shows a state in which the metal strip is thinner when the gauge is passed. The metal band 21 is, for example, stainless steel or a high nickel iron alloy, and the thickness of the boundary between the thin gauge and the thick gauge is, for example, 0.2 to 0.3 mm. In order to keep such a metal strip 21 in a reducing atmosphere,
The atmosphere gas circulation system 22 is, for example, 75% to 100% hydrogen.
Atmosphere gas whose balance is nitrogen in% is circulated in the continuous annealing apparatus 20. The atmosphere gas circulation system 22 is provided with a refining device that adsorbs moisture in the atmosphere gas and emits it to the atmosphere. At the time of thin gauge sheet passing, the temperature of the atmosphere gas blown to cool the annealed metal band 21 is increased by the heater 23, and the temperature of the atmosphere gas is increased to increase the temperature of the atmosphere.
1 is slowly cooled. In the cooling zone 24, the metal band 21 is slowly cooled when passing through the thin gauge, and is rapidly cooled by blowing an atmosphere gas having a lowered temperature when passing through the thick gauge. Atmospheric gas blown to the cooling zone 24 is sucked by the high-temperature blower 25, and is supplied to the pre-
6. The supplied atmospheric gas is sprayed on the surface of the metal strip 21 in the pre-tropical zone 26, collected by the low-temperature blower 27, and returned to the cooling zone 24 via the cooler 28. In the cooler 28, the ambient gas is cooled, and
1, so that the metal strip 21 can be rapidly cooled. Thus, when passing through a thick gauge,
High-temperature path 2 from high-temperature blower 25 to pre-tropical zone 26
9 and a low-temperature side path 30 for guiding the atmospheric gas from the pre-tropical zone 26 to the cooling zone 24 via the cooler 28 to circulate the atmospheric gas.

The discharge side of the high-temperature blower 25 and the high-temperature side path 29
A first preheating switching valve 31 is provided between the two. A second preheating switching valve 32 is provided between the high-temperature side path 29 and the pre-tropical zone 26. A third preheating switching valve 33 is provided between the pre-tropical zone 26 and the low-temperature side path 30. A fourth preheating switching valve 34 is provided between the low-temperature path 30 and the cooling zone 24. First preheating switching valve 31 and high temperature blower 25
A gentle cooling path 35 is provided between the heater 23 and a portion connected to the discharge side. A first and second connection path 3 is provided between a connection portion between the first and second preheating switching valves 31 and 32 and the high-temperature side path 29 and the atmosphere gas circulation system 22.
6, 37 are provided respectively. Fourth preheating switching valve 3
4, a connection portion between the cooler 28 and the low-temperature side path 30,
A third connection path 38 is provided between the third connection path 38 and the atmosphere gas circulation system 22.
Is provided. Third preheating switching valve 33 and low-temperature blower 27
A fourth connection path 39 is provided between the connection portion with the low temperature side path 30 and the atmospheric gas circulation system 22.
A slow cooling switching valve 40 is provided between the discharge side of the high temperature side blower 25 and the heater 23. Between the connection between the first and second preheating switching valves 31 and 32 and the high-temperature side path 29 and the first and second connection paths 36 and 37, the first connection is provided near the inlet near the connection. And second connection switching valves 41, 42
Are respectively provided. A fourth connection switching valve 44 is provided between the connection portion between the third preheating switching valve 33 and the low temperature side blower 27 and the low temperature side path 30 and the fourth connection path 39. A third connection switching valve 43 is provided between the connection portion between the outlet side of the cooler 28 and the third preheating switching valve 33 and the third connection path 38. The third and fourth connection switching valves 43 and 44 are also provided near the inlet near the connection portion.

FIG. 1 (a) shows that when the metal strip 21 is a thick gauge, the first to fourth preheating switching valves 31 to 34 are opened, and the slow cooling switching valve 40 indicated by oblique lines and First to first
The state in which the fourth connection switching valves 41 to 44 are closed is shown. The metal strip 21 travels upward in the pre-tropics 26 and travels downward in the cooling zone 24. In the cooling zone 24, the atmosphere gas cooled by the cooler 28 is blown through a fourth preheating switching valve 34 in order to cool the annealed metal zone 21. Atmosphere gas used for cooling is a high-temperature blower 25
Is supplied from the first preheating switching valve 31 to the pre-tropical zone 26 via the high-temperature side path 29 and the second preheating switching valve 32, and preheats the metal strip 21. The atmosphere gas cooled by heat exchange with the metal strip 21 is sucked by the low-temperature blower 27 through the third preheating switching valve 33 and is cooled by the cooler 2.
After being further cooled at 8, it is supplied to the cooling zone 24 via the fourth preheating switching valve 34. At the time of passing through the thick gauge, the atmospheric gas is circulated and used through the cooling zone 24, the high temperature side path 29, the pre-tropical zone 26 and the low temperature side path 30 in this way.

When the thin gauge metal strip 21 shown in FIG. 1 (b) is passed, the first to fourth preheating switching valves 31 to 34 shown by oblique lines are closed, and the slow cooling switching valve 40 and the 1st to 4th
The connection switching valves 41 to 44 are opened. As a result, the cooling zone 24
Then, after the atmospheric gas used for cooling is sucked by the high-temperature blower 25, the switching valve 40 for gentle cooling and the heater 2
3 and is circulated through the slow cooling path 35 including the cooling water.
The high-temperature side path 29 and the low-temperature side path 30 include the first and second connection switching valves 41 and 42 and the first and second connection paths 3.
6, 37 and third and fourth connection switching valves 43, 4
4 and a circulation path is formed between the atmosphere gas circulation system 22 via the third and fourth connection paths 38 and 39, respectively, and the atmosphere gas is circulated to a refining device provided in the atmosphere gas circulation system 22, The adsorbed moisture is released to the atmosphere so that no stagnation occurs. Although the metal zone 21 is not preheated in the pre-tropics 26, the metal zone 21 is a thin gauge material, so that the temperature can be quickly raised to a predetermined temperature in the annealing furnace. After the annealing, in the cooling zone 24, the atmosphere gas heated by the heater 23 is blown to cool down, so that
Slow cooling can be performed to prevent wrinkles and the like. When the thickness of the metal strip 21 is switched to the thickness gauge material, the thickness of FIG.
In the state shown in (a), the preheating gas sprayed on the surface of the metal strip 21 in the pre-tropics 26 is provided in the atmosphere gas circulation system 22 even when the thin gauge is passed, and is circulated to the refining device that adsorbs moisture. Since the adsorbed moisture is radiated to the atmosphere, there is no absorption of moisture and coloring can be prevented.

FIG. 2 shows a simplified overall structure of the continuous annealing apparatus 20 of the present embodiment. In order to change the moving direction of the metal strip 21 supplied to the entrance chute 51 from upward to downward, the vertical furnace body 50 has a top roll 52 at the top.
Is provided. The top roll 52 is formed of a heat-resistant rubber material or the like so as not to damage the surface of the metal band 21. The metal strip 21 whose moving direction has been changed downward by the top roll 52 is heated to a predetermined annealing temperature in an annealing furnace 53 and cooled by cooling devices 54 and 54 ′. Cooling needs to be performed to a temperature at which the metal strip 21 is not burned by a downstream feed roll or the like following the continuous annealing apparatus 20.
The cooling zone 24 shown in FIG. 1 is provided in the cooling device 54 ′ on the upstream side, and the high-temperature blower 25 sucks the atmospheric gas from the atmospheric gas outlet 55 and supplies it to the preheating device 56 provided on the inlet chute 51. . The preheating device 56 includes the pre-tropical zone 26 shown in FIG. 1, and the atmospheric gas used for preheating is sucked from the atmospheric gas outlet 57 by the low-temperature blower 27,
It is supplied to a cooling device 54 '. The control of the passing speed of the metal strip 21 and each switching valve in the continuous annealing device 20 is performed by the control device 60. Inlet chute 51 provided in vertical furnace body 50, annealing furnace 53 and cooling device 5
An outlet seal 62 and an outlet seal 63 are provided on the outlet chute 61 provided with the vertical furnace body 5, 54, 54 ′, respectively.
The reducing atmosphere within 0 is maintained. Atmosphere gas is supplied from the atmosphere gas supply device 58 such that the pressure of the atmosphere gas in the vertical furnace body 50 becomes slightly higher than the atmospheric pressure, and the atmosphere is supplied from the inlet seal 62 and the outlet seal 63 to the vertical furnace body. 50 so as not to enter.

FIG. 3 shows a continuous annealing furnace 20 according to the embodiment of FIG.
The procedure of controlling each switching valve when performing continuous annealing of the metal strip 21 will be described with reference to FIG. In step a1, control for starting the annealing process by passing the metal strip 21 through the continuous annealing apparatus 20 in the stopped state is started. In step a2, the temperature of the annealing furnace 53 is raised to a predetermined temperature, the connection switching valves 41 to 44 are opened, and the gas is replaced to prepare a state in which the metal strip 21 can be passed. In step a3, it is determined whether or not the metal strip 21 to be passed is a thin gauge material. This determination may be made based on the thickness data of the metal band 21 sent as data from the system for managing the production process, or may be made by actually measuring the actual thickness of the metal band 21. When it is determined in step a3 that the material is a thin gauge material, in step a4, the first to fourth preheating switching valves 31 to 34 are closed, and the slow cooling switching valve 40 and the first to fourth connection valves are connected. The switching valves 41 to 44 are opened. When it is determined in step a3 that the material is not a thin gauge material, in step a5, the slow cooling switching valve 40 and the first to fourth connection switching valves 41 to 44 are closed, and the first to fourth preheating switching are performed. Open valves 31-34. When the processing for one main metal strip 21 is completed, in step a6, the continuous annealing
It is determined whether or not to continue the processing of the metal strip 21 by.
If it is determined to continue, the process returns to step a3.
At this time, if the processing has been performed by passing the thin gauge material until then, when switching to the thick gauge material, the atmosphere gas in the high temperature side path 29 and the low temperature side path 30 is circulated even when the thin gauge material is passed. Therefore, even if the material is switched to a thick gauge material and preheating is performed by the preheating device 56, there is no possibility that coloring or the like will occur on the surface of the metal band 21. When it is determined in step a6 that the processing of the metal strip 21 is not to be continued, each switching valve is set in the same state as in step a4, and the heater 23 is turned off. The connection switching valves 41 to 44 are opened, but control is performed to stop the processing by the continuous annealing device 20 without flowing the gas, and the procedure is stopped at step a7.

According to this embodiment, regardless of whether the metal strip 21 is a thick gauge material or a thin gauge material, the metal strip 21 is continuously processed by the same continuous annealing apparatus 20 and colored when preheating the thick gauge material. In addition, it is possible to prevent quality deterioration such as wrinkling when cooling the thin gauge material, and to efficiently perform production.

[0021]

As described above, according to the present invention, by switching by the switching valve group, for example, at the time of passing through a thick gauge, the atmospheric gas circulates between the cooling zone and the pre-tropical zone, and an energy saving effect can be obtained. it can. At the time of thin gauge passing, the atmosphere gas heated through the heating path is blown to the metal band in the cooling zone, and the cooling is performed slowly to prevent the generation of wrinkles. At this time, since the atmospheric gas in the circulation path is circulated to the refining device that adsorbs moisture and dissipates the adsorbed moisture to the atmosphere, it is switched from a thin gauge material to a thick gauge material, and Even if the atmosphere gas is sprayed on the surface of the metal strip by the pre-tropical zone, it is possible to prevent the surface of the metal strip from being colored, and it is possible to switch quickly and improve the production efficiency.

According to the present invention, a high-temperature side path and a low-temperature side path are provided between the cooling zone and the pre-tropical zone to form a circulation path. Effective utilization can be achieved. When the thin gauge is passed, the connection switching valve opens for the atmosphere gas in the high-temperature path and the low-temperature path and is connected to the connection path. It is possible to prevent the surface of the metal band from being colored even if the state is switched to the state at the time of passing.

Further, according to the present invention, at the time of passing through the thick gauge, an atmosphere gas is blown to the annealed metal band to cool the metal band, heat exchange with the metal band is performed to collect the atmosphere gas having an increased temperature, and the atmosphere gas before the annealing is recovered. Since the metal strip is preheated by spraying, it is possible to obtain an energy-saving effect, and at the same time, it is possible to shorten the temperature rise time and the cooling time of the metal strip and improve the productivity. At the time of passing through the thin gauge, the temperature of the atmosphere gas for cooling the annealed metal strip is raised, so that the metal strip is not rapidly cooled, so that generation of wrinkles and the like can be prevented. Since the atmosphere gas is circulated so as to be preheated after cooling when passing through the thick gauge, the atmosphere gas is circulated even when passing through the thin gauge, so that the moisture in the atmosphere gas can be removed by the refining device, When the preheating is restarted by switching from the thin gauge to the thick gauge, coloring of the metal band due to moisture can be prevented.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view showing a schematic configuration of a cooling zone 24 and a pre-tropical zone 26 of a continuous annealing apparatus 20 according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view schematically showing the entire configuration of a continuous annealing apparatus 20 including a cooling zone 24 and a pre-tropical zone 26 in FIG.

FIG. 3 is a flowchart showing an operation procedure of the continuous annealing apparatus 20 of the embodiment of FIG.

FIG. 4 is a vertical sectional view showing a schematic configuration of a conventional continuous annealing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Continuous annealing apparatus 21 Metal strip 22 Atmospheric gas circulation system 23 Heater 24 Cooling zone 25 High-temperature blower 26 Pre-tropical 27 Low-temperature blower 28 Cooler 29 High-temperature side path 30 Low-temperature side path 31-34 Preheating switching valve 40 Slow cooling switching valve 41 -44 Connection switching valve 50 Vertical furnace body 51 Inlet chute 52 Top roll 53 Annealing furnace 54, 54 'Cooling device 56 Preheating device 58 Atmospheric gas supply device 60 Control device

Claims (3)

[Claims] 1. An inlet chute for passing a metal strip upward is provided with a pre-tropical zone for blowing a reducing atmosphere gas to preheat the metal strip, and is inverted at the top of the inlet chute and passed downward. In a continuous reducing atmosphere annealing apparatus for a metal strip, the apparatus includes a heating zone for performing heating for annealing treatment on the metal strip, and a cooling zone for spraying a reducing atmosphere gas to the annealed metal strip to cool the metal strip. Atmosphere gas formed between the zone and the pre-tropical zone and used to cool the metal zone from the cooling zone is collected and supplied to the pre-tropical zone, and the atmospheric gas used to pre-heat the metal zone from the pre-tropical zone is collected. A circulation path equipped with a refining device that circulates atmospheric gas and adsorbs moisture so that it is supplied to the cooling zone, and recovers the atmospheric gas used to cool the metal zone from the cooling zone and raises the temperature. Temperature rise for returning to the cooling zone And a switching valve group that switches between the circulation path and the heating path according to the thickness of the metal band so that the temperature of the cooling zone adapts to the thickness of the metal band. Continuous reducing atmosphere annealing equipment for belts. 2. The high-temperature side route from the cooling zone to the pre-tropical zone, the low-temperature side route from the pre-tropical zone to the cooling zone, and a high-temperature side route and a low-temperature side route are partially connected. The switching valve group includes a preheating switching valve provided on the high-temperature side path and the low-temperature side path, and a connection switching valve provided near each inlet of the connection path. The continuous reducing atmosphere annealing apparatus for a metal strip according to claim 1, wherein: 3. In a reducing atmosphere, the metal strip is supplied while being passed upward, the sheet passing direction is reversed at the top, and the metal strip passed downward is heated and annealed to reduce In a continuous reducing atmosphere annealing method for a metal strip, which cools by blowing an atmosphere gas, a reducing atmosphere including a refining device that adsorbs moisture between a part where a passing direction of a metal strip is upward and a part where a downward direction is passed. A gas circulation path is formed, and when the metal strip is passed through a thick gauge, the circulation path is used to collect the atmosphere gas that has cooled the annealed metal strip, and to pass it through the metal strip passing upward. Spray and preheat,
Atmosphere gas that has preheated the metal strip is collected and circulated so that it is sprayed and cooled on the annealed metal strip that passes downward, and when the thin metal gauge is passed through the thin gauge, the annealed metal strip is cooled. Collect the ambient gas that has been collected, raise the temperature and circulate it to blow it to the cooling of the metal strip, and circulate the atmosphere gas in the circulation path without spraying the metal strip passing upward. Characteristic is a continuous reducing atmosphere annealing method for metal strips.