JP4070067B2 - Switchable continuous heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention continuously heats and soaks the steel strip, then performs primary cooling, and if necessary, performs over-aging treatment, then performs secondary cooling, and further heat treatment by final cooling. Further, the present invention relates to a switchable continuous heat treatment facility that can be used in the same facility as a continuous hot dip galvanization facility that performs hot dip galvanization after heat treating a steel strip.
[0002]
[Prior art]
Continuously heat treatment equipment for heat treatment of steel strip and steel strip treated by continuous heat treatment furnace are subsequently introduced into the hot dipping pot via snout, and hot dipping pot by means of plating adhesion amount controller such as gas wiping nozzle For example, Japanese Patent No. 2590152 discloses a method of switching and processing a continuous hot dip galvanizing facility for performing plating by adjusting the amount of plating attached to the steel strip pulled up from the steel plate. That is, in Japanese Patent No. 2590152, a continuous annealing furnace and a plating pot are provided on the outlet side thereof, and when performing the plating process, the steel strip heat-treated in the continuous annealing furnace is subsequently passed through the snout. When a steel strip that has been introduced into the zinc pot and is subjected only to heat treatment without plating, a new deflector roll is installed on the plating pot with the wiping nozzle and other parts of the plating device removed from the plating pot. A method is described in which the steel strip from the continuous annealing furnace is redirected by using the deflector roll, and the steel strip is produced without entering the plating pot.
[0003]
JP-A-58-71366 discloses a heating zone, a soaking zone, a primary cooling zone, an overaging zone having a controlled cooling function, a hot dipping means, an intermediate cooling means, and a secondary cooling zone in series. A combined production facility for cold-rolled steel sheet and hot-dip galvanized steel sheet, which has a bypass means arranged and directly connected from the overaging zone to the secondary cooling zone, is described.
[0004]
[Problems to be solved by the invention]
However, in the case where the steel strip that has been plated and the steel strip that has been subjected only to heat treatment are separately manufactured by the conventional method disclosed in Japanese Patent No. 2590152, the just before entering the plating pot during the manufacture of the plated steel strip The steel strip temperature is about 450 ° C to 470 ° C in the case of hot dip galvanizing, and the temperature on the continuous annealing furnace exit side during the manufacture of steel strips that only undergo heat treatment (for example, cold thin material products) is close to room temperature. Alternatively, since it is necessary to set the temperature to such a level that oxidation of the steel strip surface does not substantially become a problem, for example, 150 ° C. to 200 ° C. or less, it is necessary to make the temperature considerably lower than that when the plated steel strip is passed through. For this reason, it is necessary for the continuous annealing furnace to be equipped with a large-capacity cooling device corresponding to the treatment of the steel strip that performs only the heat treatment of the cold thin material or the like in front of the plating pot. This large-capacity cooling device is indispensable in the manufacture of steel strips that only perform heat treatment of cold thin materials, etc., but on the other hand, it is not necessary in the production of plated steel strips. Sometimes, it is necessary to prevent overcooling in this cooling device in order to ensure the steel strip temperature when the plating pot enters, and it is necessary to provide a heater for heat quantity compensation. As a result, not only the equipment cost is increased, but also the temperature control of the steel strip becomes difficult. The overaging zone is also equipped with a cooling function, but in this case as well, it is necessary to install an electric heater and a cooling device necessary to keep the steel strip at the overaging temperature, so the equipment cost is reduced. An increase was inevitable.
[0005]
Furthermore, the plated steel strip after plating in hot dip galvanization or after alloying after plating must be cooled to near room temperature, and usually mist cooling or air jet cooling is used, and then approximately 180 ° C. In the range from ˜150 ° C. to near normal temperature, it is necessary to provide a final cooling zone by immersion cooling such as water quench for the purpose of improving the cooling efficiency.
[0006]
When switching between continuous hot-dip galvanization equipment and continuous heat treatment equipment such as cold thin materials, and switching to operation, the final cooling equipment after plating in hot dip galvanization or after alloying treatment, and the cold thin material treatment process However, it is not only disadvantageous in terms of installation space but also uneconomical in terms of equipment cost.
[0007]
On the other hand, in the method disclosed in JP-A-58-71366, a heating zone, a soaking zone, a primary cooling zone, an overaging zone having a controlled cooling function, a hot dipping means, an intermediate cooling means, and a secondary cooling. The strips are sequentially arranged in series, and when the plated steel strip is processed, the galvanized steel strip is approximately 400 ° C. or less by an intermediate cooling means provided between the hot dip galvanizing means and the secondary cooling zone, preferably After cooling to 350 ° C. or lower, it is subsequently cooled to approximately 300 ° C. in the secondary cooling zone. At this time, in order to prevent the zinc in the plating layer from being picked up by the hearth roll in the furnace in the secondary cooling zone, the temperature of the plated steel strip in the intermediate cooling means is set to 400 ° C. as described above, preferably Although it has been shown that the temperature is 350 ° C. or lower, there still remains a problem that even in this conventional method, it is not possible to completely prevent zinc from being picked up on the surface of the hearth roll. In particular, in the case of alloying after hot dip galvanization, fine peeling of the alloy layer of iron and zinc occurs when bending is repeatedly performed by a hearth roll in an atmosphere of 300 ° C. to 350 ° C. in the secondary cooling zone. As a result of the pick-up caused by the occurrence of defects and defects such as scratches on the surface of the plating material, it is difficult to obtain a product satisfying strict surface quality requirements.
[0008]
In addition, when the steel strip after being plated in the hot dip galvanizing pot is subsequently alloyed, it is necessary to temporarily retract the bypass furnace to off-line and then install the alloying device in-line. Since a separate apparatus for moving the bypass furnace and an apparatus for moving the alloying apparatus in-line are required separately, there is a disadvantage that the moving apparatus becomes complicated and at the same time requires a lot of time for switching work. Furthermore, when disconnecting the bypass furnace from the overaging zone and the secondary cooling zone, or reattaching the bypass furnace, it is done by removing the bolt fastening at the flanges at both ends, but even after the bolts are removed, the overaging zone and Since the distance between the surfaces of the fixed flange on the secondary cooling zone side is unchanged, it is difficult to secure the necessary gap when moving the bypass furnace. Since it is essential to close the flange on the side of the belt and the secondary cooling zone with a blind cover and maintain the non-oxidizing gas atmosphere in the furnace, these series of operations required a great deal of time. The time required for this switching, that is, the productivity of the dual-use line is significantly reduced.
[0009]
The present invention solves such problems and enables the production of heat-treated steel sheets such as plated steel and cold thin material with excellent surface quality by avoiding the pick-up of zinc to the hearth roll, and switching of the bypass furnace The purpose of this is to make the equipment compact and to keep equipment costs to a minimum.
[0010]
[Means for Solving the Problems]
The present invention is a primary overaging of a continuous heat treatment facility in which a heating zone, a soaking zone, a primary cooling zone, a primary overaging zone, a secondary overaging zone, a secondary cooling zone, and a water quench type final cooling zone are sequentially arranged in series. A plating pot for hot galvanizing the steel strip, a plating adhesion amount adjusting device, an alloying device and a cooling device are sequentially provided between the strip and the secondary overaging zone, and the plated steel strip is further provided to the final cooling zone. A bypass for allowing a plate to pass through the upper and lower outer shells of the secondary overaging zone and the secondary cooling zone and allowing the steel strip to pass directly from the primary overaging zone to the secondary overaging zone is provided in the alloy. An alloying device crossing portion and a bypass crossing portion which are provided so as to intersect with the alloying device and each have a steel strip guide path inside are mounted on the moving carriage adjacent to each other, and the moving carriage is connected to the alloying device and the bypass. At the intersection of the two Select one of the apparatus cross section and the bypass cross-section without freely switch the path of the strip, so as to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip It is characterized by that.
[0011]
In addition, the present invention includes a primary cooling zone and an overaging zone of a continuous heat treatment facility in which a heating zone, a soaking zone, a primary cooling zone, an overaging zone, a secondary cooling zone, and a water quench type final cooling zone are sequentially arranged in series. In the meantime, a plating pot for performing hot dip galvanizing on the steel strip, a plating adhesion amount adjusting device, an alloying device and a cooling device are sequentially provided, and a path for passing the plated steel strip to the final cooling zone is further provided. is provided on a furnace殼外top or bottom of the aging zone and a secondary cooling zone, the bypass allowed to directly through plate steel strip from the primary cooling zone to overaging zone, provided so as to intersect with said alloying apparatus, the steel inside each An alloying device intersection having a belt guideway and a bypass intersection are placed adjacent to each other on a movable carriage, the movable carriage is provided at the intersection of the alloying device and the bypass, and the movable carriage is moved. Bypass intersection with alloying device intersection Select one of the parts without freely switch the path of the steel strip, characterized in that to be able to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip.
[0012]
Furthermore, the present invention provides an overaging zone and a secondary cooling zone of a continuous heat treatment facility in which a heating zone, a soaking zone, a primary cooling zone, an overaging zone, a secondary cooling zone, and a water quench type final cooling zone are sequentially arranged in series. Between, a plating pot for performing hot dip galvanizing on the steel strip, a plating adhesion amount adjusting device, an alloying device and a cooling device are sequentially provided, and a path through which the plated steel strip is passed to the final cooling zone, is provided on a furnace殼外top or bottom of the secondary cooling zone, the steel strip a bypass allowed to direct communication board to the secondary cooling zone from overaging zone, provided so as to intersect with said alloying apparatus, inside of the steel strip, respectively An alloying device intersection having a guide path and a bypass intersection are placed adjacent to each other on a moving carriage, the moving carriage is provided at an intersection between the alloying device and the bypass, and the moving carriage is moved to form an alloy. Between crossover and bypass crossing Or None selected and freely switch the path of the steel strip, characterized in that to be able to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip.
[0014]
The bypass is composed of an entry-side bypass portion, a bypass intersection portion, and an exit-side bypass portion, and an expansion tube is attached to the entry-side bypass portion and the exit-side bypass portion, It can be made connectable via a telescopic tube.
[0015]
Furthermore, a sealing device for sealing the furnace atmosphere can be provided on the entrance side of the snout for guiding the steel strip to the hot dipped pot, and the furnace atmosphere is shut off from the outside on the entry side and the exit side of the bypass respectively. A sealing device can be provided.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a sectional view showing an embodiment of the present invention. The continuous heat treatment furnace includes a heating zone 2, a soaking zone 3, a primary cooling zone 4, a primary overaging zone 5 for performing an overaging treatment, a secondary overaging zone 6, a secondary cooling zone 7, 1 quench tank 8 and No. 1 The final cooling zone is composed of two quench tanks 9. In this embodiment, the primary overaging zone 5 and the secondary overaging zone 6 perform exactly the same function of holding the primary cooled steel strip 1 for a certain period of time and performing overaging treatment. It is only divided into independent chambers (bands) due to structural problems, and it depends on the individual design whether it is divided into two chambers or one chamber according to the required overaging time To be determined.
[0017]
The steel strip 1 is passed through a heating zone 2, a soaking zone 3, a primary cooling zone 4 and a primary overaging zone 5 in this order. Thereafter, when passing a heat treatment material such as a cold thin material, the secondary overaging zone 6 and the secondary are passed through the bypass 35 constituted by the inlet side bypass portion 22, the switching device 23 and the outlet side bypass portion 24. Sent to the cooling zone 7 and then 1 quench tank 8 and No. 1 After the final cooling in the final cooling zone composed of two quench tanks 9, it is dried by a dryer 10 and sent to the next step.
[0018]
On the other hand, between the primary overaging zone 5 and the secondary overaging zone 6, a molten zinc plating pot 12, a plating adhesion amount adjuster 13, an alloying device 14, and a cooling device 15 are arranged in series in the vertical direction. ing.
[0019]
2 (a) and 2 (b) are cross-sectional views showing an example of a plate through which a steel strip is plated. At the time of manufacturing the hot dip galvanized steel strip, as shown in FIG. 2 (a), the steel strip 1 is passed through the heating zone 2, the soaking zone 3, the primary cooling zone 4 and the primary overaging zone 5 in this order, and then the primary excess It is introduced into a hot dip zinc plating pot 12 via a snout 11 connected to the aging zone 5, adjusted to a predetermined plating thickness by a plating adhesion amount adjuster 13, and if necessary in an alloying device 14. After the alloying treatment, the cooling device 15 is cooled to a predetermined temperature or lower, passes through the inlet-side top roll 16 and the outlet-side top roll 17, and is reduced to approximately 200 ° C. or lower by the air jet cooler type cooling device 18. To be cooled. At this time, the switching device 23 is switched and arranged so that the plated steel strip can be passed through in the vertical direction. The upper part of the secondary overaging zone 6 and the secondary cooling zone 7 outside the furnace shell is provided with a path 20 through which the plated steel strip 1 is passed to the quench tank 9 which is the final cooling zone. After the steel strip 1 is cooled by the jet cooler type cooling device 18, the direction is changed by the deflector roll 19, and after passing through the path 20, the steel strip 1 is sent to the quench tank 9 by the deflector roll 21 and finally cooled. .
[0020]
FIG.2 (b) shows another example of the passing plate of the steel strip plated. The plated steel strip 1 cooled by the air jet cooler type cooling device 18 is changed in direction by a deflector roll 19 disposed in the lower part outside the furnace shell before the secondary overaging zone 6, and the secondary overaging zone 6 After being transported along the path 20 provided in the lower part of the secondary cooling zone 7 outside the furnace shell, it is sent to the quench tank 9 via the quench tank 8 and finally cooled.
[0021]
In the present invention, the plating pot 12, the plating adhesion amount adjuster 13, the alloying device 14, and the cooling device 15 are arranged in the vertical direction, and the steel strip 1 passes through the entry-side top roll 16 and the exit-side top roll 17. The direction is changed downward, and the jet cooler 18 is cooled to 200 ° C. or lower. During this time, the steel strip 1 is in contact with only the entry-side top roll 16 and the exit-side top roll 17 and is repeatedly bent by the hearth roll in the furnace as in the prior art (Japanese Patent Laid-Open No. 58-71366). Therefore, there is no problem of picking up zinc to the hearth roll, and therefore there is no pressing scratch on the surface of the plated steel strip.
[0022]
FIGS. 3A and 3B are sectional views showing another embodiment of the continuous heat treatment furnace.
[0023]
In the configuration shown in FIGS. 1 and 2, a plating pot 12, a plating adhesion amount adjuster 13, an alloying device 14, and a cooling device 15 are arranged between the primary overaging zone 5 and the secondary overaging zone 6. As shown in FIG. 3A, a plating pot 12, a plating adhesion amount adjusting device 13, an alloying device 14, and cooling devices 15 and 18 may be arranged between the primary cooling zone 4 and the overaging zone 33. Further, as shown in FIG. 3B, a plating pot 12, a plating adhesion amount adjuster 13, an alloying device 14, and cooling devices 15 and 18 are arranged between the overaging zone 33 and the secondary cooling zone 7. May be.
[0024]
As shown in FIG. 3A, by providing a plating facility between the primary cooling zone 4 and the overaging zone 33, the steel strip 1 is introduced into the plating pot 12 following the primary cooling zone 4 when the plated steel strip is manufactured. Therefore, it is not necessary to pass the overaging band 5 as shown in FIG. Accordingly, the overaging zone 33 in FIG. 3 (a) is applied only to the manufacture of heat-treated steel strips such as cold thin materials, and the overaging zone 33 is suitable for the overaging treatment of the heat-treated steel strip. Therefore, in the embodiment shown in FIG. 1, the maximum temperature in the furnace must be designed to be 470 ° C. to 500 ° C. in consideration of the plated steel strip. Compared to this, the embodiment of FIG. 3A has an advantage that an overage zone can be provided at a low cost.
[0025]
Further, as shown in FIG. 3B, by providing a plating facility between the overaging zone 33 and the secondary cooling zone 7, the cooling temperature is not uniform in the width direction of the steel strip in the cooling process in the primary cooling zone 4. In this case, the steel strip 1 is passed through the overaging zone 33 while being kept at a constant temperature, so that the effect of uniforming the temperature unevenness in the width direction of the steel strip 1 can be expected. Thus, the temperature of the steel strip 1 penetrating the steel plate 12 can be made uniform, and there is an effect that the plating adhesion amount can be made uniform and the plating adhesion can be improved.
[0026]
FIG. 4 is a perspective view showing an example of a bypass switching structure according to the present invention. FIG. 4A shows a case where a plated steel plate is passed, and FIG. 4B shows a case where a heat treated steel strip is passed. The alloying device 14 and the bypass 35 are adjacent to each other with an alloying device crossing portion 25 for the plated steel plate passing plate and a bypass crossing portion 26 for the heat-treated steel strip passing plate having a guide path for the steel strip 1 inside. The moving carriage 27 is moved by a traversing device (not shown). In the bypass 35, the alloying device intersection 25 is moved to an in-line position when the plated steel strip is passed, and the bypass intersection 26 is located offline. Telescopic tubes 28 and 29 are attached to the respective distal ends of the inlet bypass portion 22 and the outlet bypass portion 24. When the alloying device intersection 25 and the bypass intersection 26 are switched, the expansion tubes 28, Reference numeral 29 is saved in a reduced size to secure a clearance required for the switching operation. The contraction of the telescopic tubes 28 and 29 is performed using an air cylinder or the like.
[0027]
FIG. 4B shows a state where the heat treatment steel strip is switched to the bypass, where the bypass intersection 26 stops at the inline position, and the alloying device intersection 25 escapes to the offline side. The telescopic pipes 28 and 29 are flange-joined to the bypass intersection 26 by expansion and contraction, respectively, and the inlet bypass section 22 and the outlet bypass section 24 are hermetically joined via the bypass intersection 26.
[0028]
FIG. 5 is a cross-sectional view showing an example in which a sealing device for shielding the furnace atmosphere is provided, and a sealing device 30 for shielding the furnace atmosphere is provided on the entrance side of the snout 11. Further, sealing devices 31 and 32 for shielding the atmosphere gas in the furnace are provided in the heat treatment steel plate passage route before and after the switching device 23, that is, in the inlet side bypass portion 22 and the outlet side bypass portion 24 of the bypass 35. By closing these sealing devices 31 and 32, even when the connection portion is released to the atmosphere when switching between the alloying device intersection 25 and the bypass intersection 26, the atmosphere is introduced into the inlet bypass portion 22 and the outlet bypass. It is possible to prevent the front and rear annealing furnaces from entering through the section 24.
[0029]
【effect】
The present invention can achieve the following effects.
[0030]
(1) Since there is no need to install a large capacity cooling facility that cools the steel strip to near room temperature or an overaging zone with a controlled cooling function at a location located in front of the plating pot, It becomes easy to control the pot penetration plate temperature.
[0031]
(2) Since the final cooling equipment can be used for both the heat-treated steel strip passing plate and the plated steel strip passing plate, it is not necessary to provide each separately, thereby reducing the equipment cost and reducing the installation space. Can be small.
[0032]
(3) Since the plated steel strip is led to the final cooling zone without passing through the furnace after plating, there is a problem of zinc trapping or picking up in the hearth roll in the secondary overaging zone, secondary cooling zone, etc. Is eliminated, and a plated steel strip and a heat-treated steel strip excellent in surface quality can be manufactured.
[0033]
(4) To adopt a switching device for switching the line by placing the alloying device intersection and the bypass intersection on the movable carriage of the present invention at the portion for switching the plated steel belt passage route and the heat-treated steel belt passage plate route. Thus, it is not necessary to move the entire long bypass as in the prior art, and the moving device itself can be made compact.
[0034]
(5) When switching the path, the alloying device intersection for plated steel strip passage and the bypass intersection for heat-treated steel plate passage are adjacent to each other and are loaded on the same moving carriage. Expansion and contraction pipes are fixed to the front and rear entrance bypass sections and the exit bypass section, and when the path is switched, the expansion and contraction pipes are structured to ensure a necessary and sufficient gap. It becomes possible to switch quickly, and time loss due to switching can be minimized.
[0035]
(6) While preventing the intrusion of air into each zone of the front and rear heat treatment furnaces by using a sealing device that shields the atmospheric gas in the furnace provided at the entrance side of the snout, the entrance bypass section and the exit bypass section Since the switching operation can be performed, the purge time for replacement with the furnace atmosphere can be saved, and the operation efficiency can be further improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of a steel plate that has been plated.
FIG. 3 is a sectional view showing another embodiment of a continuous heat treatment furnace.
FIG. 4 is a perspective view showing an example of a bypass switching structure according to the present invention.
FIG. 5 is a cross-sectional view showing an example in which a sealing device for shielding the furnace atmosphere is provided.
[Explanation of symbols]
1: Steel strip 2: Heating zone 3: Soaking zone 4: Primary cooling zone 5: Primary overaging zone 6: Secondary overaging zone 7: Secondary cooling zone 8: No. 1 quench tank 9: No. 1 2 Quench tank 10: Dryer 11: Snout 12: Plating pot 13: Plating adhesion amount controller 14: Alloying device 15: Cooling device 16: Inlet side top roll 17: Outlet side top roll 18: Air jet cooler type cooling device 19 : Deflector roll 20: Path 21: Deflector roll 22: Inlet bypass section 23: Switching device 24: Outlet bypass section 25: Alloying device intersection 26: Bypass intersection 27: Moving carriage 28: Telescopic tube 29: Telescopic tube 30: Sealing device 31: Incoming atmosphere blocking device 32: Outgoing atmosphere blocking device 33: Overage zone 35: Bypass

Claims (6)

Primary overaging zone and secondary zone of continuous heat treatment equipment in which heating zone, soaking zone, primary cooling zone, primary overaging zone, secondary overaging zone, secondary cooling zone and water quench type final cooling zone are arranged in series A path through which a plating pot for applying hot dip galvanizing to a steel strip, a plating adhesion amount adjusting device, an alloying device, and a cooling device are provided in order during the overaging zone, and the plated steel strip is passed to the final cooling zone. At the upper or lower portion of the secondary overage zone and the secondary cooling zone outside the furnace shell, and a bypass that allows the steel strip to pass directly from the primary overaging zone to the secondary overaging zone intersects the alloying device. And an alloying device crossing portion and a bypass crossing portion , each having a steel strip guide path inside , are placed adjacent to each other on the moving carriage, and the moving carriage is placed at the intersection of the alloying device and the bypass. And move the movable carriage to exchange the alloying device. None freely switch the path of the steel strip by selecting one of the parts and the bypass cross-section, that it has to be able to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip A switchable continuous heat treatment facility. Heating zone, soaking zone, primary cooling zone, overaging zone, secondary cooling zone and water quench type final cooling zone are arranged in series between the primary cooling zone and the overaging zone of the continuous heat treatment equipment. A plating pot for performing hot dip galvanization, a plating adhesion amount adjusting device, an alloying device, and a cooling device are sequentially provided, and a path through which the plated steel strip passes through to the final cooling zone is provided with the overaging zone and secondary cooling. A bypass that allows the steel strip to pass directly from the primary cooling zone to the overaging zone is provided across the alloying device, and each has a steel strip guide path inside. An alloying device intersection and a bypass intersection are placed adjacent to each other on a moving carriage, the moving carriage is provided at the intersection of the alloying device and the bypass, and the moving carriage is moved to move the alloying device intersection. And one of the bypass intersections -Option none freely switch the path of the steel strip, the switchable continuous heat treatment facility, characterized in that to be able to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip. Steel zone between the overaging zone and the secondary cooling zone of the continuous heat treatment equipment where heating zone, soaking zone, primary cooling zone, overaging zone, secondary cooling zone and water quench type final cooling zone are arranged in series A plating pot for performing hot dip galvanizing, a plating adhesion amount adjusting device, an alloying device, and a cooling device are sequentially provided, and a path for passing the plated steel strip to the final cooling zone is provided in the furnace of the secondary cooling zone. An alloy is provided in the upper or lower part of the outer wall, and a bypass that allows the steel strip to pass directly from the over-aged zone to the secondary cooling zone intersects with the alloying device, and has a steel strip guide path inside. An apparatus intersection and a bypass intersection are placed adjacent to each other on a movable carriage, the movable carriage is provided at an intersection between the alloying apparatus and the bypass, and the movable carriage is moved to bypass the alloying apparatus intersection and the bypass. steel strip by selecting one of the intersection None freely switched path, switching type continuous heat treatment facility, characterized in that to be able to perform switching to the production of continuous heat treatment steel strip and the production of continuous galvanizing steel strip.   The bypass is composed of an entry-side bypass portion, a bypass intersection portion, and an exit-side bypass portion, and an expansion tube is attached to the entry-side bypass portion and the exit-side bypass portion, and the bypass intersection portion is the expansion tube. The switchable continuous heat treatment facility according to any one of claims 1 to 3, wherein the switchable continuous heat treatment facility is capable of being connected via a switch.   The switching-type continuous heat treatment equipment according to any one of claims 1 to 3, wherein a sealing device for sealing the atmosphere in the furnace is provided on the entrance side of the snout for guiding the steel strip to the plating pot.   The switchable continuous heat treatment facility according to any one of claims 1 to 3, wherein a seal device for shutting off the atmosphere in the furnace from the outside is provided on the entry side and the exit side of the bypass.

Images