Continuous heat treatment facility and continuous heat treatment method for steel strip

Abstract

To provide a continuous heat treatment facility for a steel strip, which continuously heats, cools, and treats a steel strip, and in which a case where the steel strip is continuously heated, cooled, and plated and a case where the steel strip is continuously heated, cooled, and then over-aged are easily switched without wasting a path of an over-aging zone for moving the annealed steel strip and without increasing running cost.SOLUTION: In a continuous heat treatment facility for a steel strip for continuously heating, cooling and treating a steel strip W, a switching region 10 capable of switching between a heating region 11 for heating the steel strip and an over-aging region 12 for over-aging the heated and cooled steel strip is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a continuous heat treatment facility for steel strips that continuously heats and cools the steel strips. and continuous heat treatment method In particular, the present invention is characterized by the fact that it is possible to easily switch between a case in which a steel strip is continuously heated and cooled to be plated, and a case in which a steel strip is continuously heated and cooled and the heated and cooled steel strip is subjected to overaging treatment. [Background technology]

[0002] Conventionally, as a continuous heat treatment equipment for a steel strip in which the steel strip is continuously heated and cooled, for example, as shown in Patent Document 1, an annealing furnace is used in which a heating zone, a soaking zone, and a cooling zone are provided in that order, and a hot-dip galvanizing facility is provided adjacent to the cooling zone of the annealing furnace, and the steel strip annealed in the annealing furnace is subjected to a galvanizing treatment, thereby heating and alloying the galvanized strip.

[0003] On the other hand, when the annealed steel strip is to be used without plating, the steel strip annealed by heating and cooling as described above is usually subjected to overaging treatment.

[0004] Patent Document 2 discloses a surface-treated steel sheet manufacturing facility in which a steel sheet is manufactured by traveling through a heating zone, a soaking zone, a slow-cooling zone, a quenching zone, an over-aging zone, a galvanizing zone, and a final cooling zone in this order, and the facility is configured to have a route switching mechanism that switches between a traveling route in which the steel sheet transported from the over-aging zone is immersed in the molten metal and travels to the final cooling zone, and a traveling route in which the steel sheet transported from the over-aging zone is traveled to the final cooling zone without being immersed in the molten metal.

[0005] In addition, in Patent Document 3, a continuous heat treatment facility is provided 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 arranged in series in this order, and between the primary overaging zone and the secondary overaging zone, a coating pot for hot dip galvanizing the steel strip, a coating weight regulator, an alloying device, and a cooling device are sequentially provided, and further, a path for passing the coated steel strip to the final cooling zone is provided at the upper or lower part of the outer furnace shell of the secondary overaging zone and the secondary cooling zone, and the steel strip is passed through the primary overaging zone and the secondary overaging zone. A bypass that allows the strip to pass directly from the aging zone to the secondary overaging zone is provided at the intersection with the alloying device, and an alloying device intersection and a bypass intersection, each having a steel strip guide path inside, are placed adjacent to each other on a movable carriage, and the movable carriage is provided at the intersection of the alloying device and the bypass, and the movable carriage is moved to select either the alloying device intersection or the bypass intersection, allowing the steel strip path to be freely switched, so that the production of continuous hot-dip galvanized steel strip and the production of continuous heat-treated steel strip can be switched between.

[0006] In the methods disclosed in Patent Documents 2 and 3, even when plating is performed on an annealed steel strip, the annealed steel strip is guided to an overaging zone to be subjected to overaging treatment.

[0007] However, when plating an annealed steel strip, it is not necessarily necessary to over-age the annealed steel strip, and the path of the over-aging zone through which the annealed steel strip moves becomes wasted. In addition, if the annealed steel strip is guided into the over-aging zone for over-aging, the temperature of the over-aged steel strip becomes lower than the temperature at which the plating is performed, and it becomes necessary to heat the over-aged steel strip to a temperature suitable for the plating, which results in problems such as high running costs. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-180137 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-024981 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-155318 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0009] The present invention relates to a continuous heat treatment facility for steel strips that continuously heats and cools the steel strips. and continuous heat treatment methods The present invention aims to solve the above-mentioned problems in the prior art.

[0010] The present invention relates to a continuous heat treatment facility for steel strips that continuously heats and cools the steel strips. and continuous heat treatment method The present invention addresses the problem of easily switching between a case in which a steel strip is continuously heated and cooled for plating treatment and a case in which the steel strip is continuously heated and cooled and the heated and cooled steel strip is subjected to overaging treatment, without wasting the path of the overaging zone through which the annealed steel strip is moved or without increasing running costs. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the continuous heat treatment equipment for steel strips according to the present invention is a continuous heat treatment equipment for steel strips that continuously heats and cools the steel strips, and is provided with a switching region that can switch between a heating region for heat-treating the steel strips and an overaging region for overaging the heated and cooled steel strips. A heating / cooling zone for heating / cooling the steel strip is provided upstream of the switching zone so as to be continuous with the switching zone, and a first introduction seal section for introducing the steel strip into the heating / cooling zone and a second introduction seal section for introducing the steel strip into the switching zone are provided. Meanwhile, a cooling zone for cooling the steel strip introduced from the switching zone is provided downstream of the switching zone, and a plating treatment facility for plating the steel strip introduced from the cooling zone and a discharge path for discharging the steel strip introduced from the cooling zone without introducing it to the plating treatment facility are provided. I made it so that.

[0012] In the continuous heat treatment equipment for steel strips of the present invention, the switching zone can be switched between a heating zone for heat-treating the steel strip and an overaging zone for overaging the heated and cooled steel strip, thereby making it possible to easily switch between zones according to the purpose of treating the steel strip.

[0013] Here, when the switching region is used as a heating region for heat-treating the steel strip, the temperature in the heating region is set to a high temperature using various heating devices, for example, the maximum furnace temperature is set to about 950°C and the steel strip is heated to about 800°C, while when the switching region is used as an overaging region for overaging the heated and cooled steel strip, the steel strip that has been heated and cooled to about 400°C is further slowly cooled to perform the overaging treatment, for example, the furnace temperature is set to about 200°C and the steel strip is slowly cooled to about 300°C.

[0014] Also, In the continuous heat treatment equipment for steel strips of the present invention, like A heating / cooling zone for heating / cooling the steel strip is provided at a position upstream of the switching zone so as to be continuous with the switching zone, and a first introduction seal section for introducing the steel strip into the heating / cooling zone and a second introduction seal section for introducing the steel strip into the switching zone are provided, while a cooling zone for cooling the steel strip introduced from the switching zone are provided at a position downstream of the switching zone, and a plating treatment facility for plating the steel strip introduced from the cooling zone and a discharge path for discharging the steel strip introduced from the cooling zone without introducing it to the plating treatment facility are provided. did.

[0015] where: In the continuous heat treatment method for steel strips according to the present invention, the above-mentioned continuous heat treatment equipment is used. As described above, when a heating / cooling zone for heating and cooling the steel strip is provided upstream of the switching zone, the steel strip is introduced into the heating / cooling zone through the first introduction seal, and the steel strip is heated and cooled in the heating / cooling zone, the switching zone can be used as an overaging zone, and the steel strip heated and cooled in the heating / cooling zone can be overaged in the overaging zone.

[0016] The steel strip that has been overaged in the overaging region as described above can be introduced into the cooling region and cooled, and the cooled steel strip can be discharged through a discharge path without being introduced into a plating treatment facility.

[0017] Also, In the continuous heat treatment method for steel strips according to the present invention, the above-mentioned continuous heat treatment equipment is used.Even when a heating / cooling zone for heating / cooling the steel strip is provided upstream of the switching zone as described above, the steel strip can be introduced into the switching zone through the second introduction seal section, and the switching zone can be used as a heating zone, and the steel strip introduced through the second introduction seal section can be heat-treated in the heating zone. In this way, the steel strip can be quickly heat-treated by using the switching zone as a heating zone without using the heating / cooling zone. can.

[0018] Then, as described above, the switching zone is used as a heating zone, and after the steel strip is heat-treated, the steel strip is introduced into the cooling zone to be cooled, and the cooled steel strip is introduced into a plating treatment facility to perform plating treatment on the steel strip. In this way, when the steel strip after heat treatment is introduced into the cooling zone to be cooled and then plated, the temperature to which the steel strip after heat treatment is cooled can be set to the temperature for plating treatment, for example, about 460°C, thereby preventing the steel strip from being excessively cooled in the cooling zone. [Effects of the Invention]

[0019] Continuous heat treatment equipment for steel strips according to the present invention and continuous heat treatment method In the present invention, a switching region is provided that allows switching between a heating region for heat-treating steel strips and an overaging region for overaging steel strips that have been heated and cooled, as described above. By switching this switching region between a heating region for heat-treating steel strips and an overaging region for overaging steel strips that have been heated and cooled, it has become possible to easily switch between the heating region for heat-treating steel strips and the overaging region for overaging steel strips that have been heated and cooled, depending on the purpose of the steel strip treatment.

[0020] As a result, the continuous heat treatment equipment for steel strips according to the present invention and continuous heat treatment method In this method, it is possible to easily switch between a case in which the steel strip is continuously heated and cooled for plating treatment, and a case in which the steel strip is continuously heated and cooled and the heated and cooled steel strip is subjected to overaging treatment, without wasting the path of the overaging zone through which the annealed steel strip is moved as in the past, or without high running costs. [Brief explanation of the drawings]

[0021] [Figure 1] In the continuous heat treatment equipment and continuous heat treatment method for steel strips according to an embodiment of the present invention, an example is shown in which the steel strip is introduced from a first introduction seal into a heating / cooling zone located upstream of a switching zone that can be switched between a heating zone for heating the steel strip and an overaging zone for overaging the heated / cooled steel strip, and this is a schematic explanatory diagram showing a configuration in which the switching zone is used as the overaging zone, the steel strip that has been heated / cooled in the heating / cooling zone is overaged in the overaging zone, and then the steel strip is cooled in the cooling zone, and the cooled steel strip is discharged through a discharge path. [Figure 2] This is a schematic explanatory diagram showing an example of the steel strip being introduced from a second introduction seal section provided in a switching area that can be switched between a heating area where the steel strip is heated and an overaging area where the heated and cooled steel strip is overaged in the steel strip continuous heat treatment equipment and continuous heat treatment method according to the above-mentioned embodiment, and showing a configuration in which the switching area is used as a heating area, the steel strip is heat treated in the heating area, the heated steel strip is cooled in the cooling area, and the cooled steel strip is then introduced into a plating treatment equipment and the steel strip is plated. BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, the continuous heat treatment equipment for steel strips according to the embodiment of the present invention will be described. and continuous heat treatment method The following will specifically explain the above with reference to the accompanying drawings. The continuous heat treatment equipment for steel strips according to the present invention is not limited to the following embodiments, and can be appropriately modified and implemented within the scope of the invention.

[0023] Continuous heat treatment equipment for steel strips in this embodiment and continuous heat treatment method As shown in Figures 1 and 2, a switching region 10 is provided that can be switched between a heating region 11 in which the steel strip W is heated and an overaging region 12 in which the heated and cooled steel strip W is overaged.

[0024] Furthermore, a heating / cooling region 20 for heating and cooling the steel strip W is provided at a position upstream of the switching region 10 in the feeding direction of the steel strip W so as to be continuous with the switching region 10 .

[0025] Here, in the heating and cooling zone 20, a pair of introduction rollers S1a are provided in the first introduction seal section S1 through which the steel strip W is introduced, and the steel strip W is introduced into the heating and cooling zone 20 while preventing outside air from entering the furnace through this pair of introduction rollers S1a.

[0026] Within the heating and cooling region 20, the steel strip W is successively moved through a heating zone 21 for heating the steel strip W, which is provided downstream in the feed direction of the steel strip W, a soaking zone 22 for soaking the heated steel strip W, and a cooling zone 23 for cooling the soaked steel strip W, in that order.

[0027] In addition, in the switching area 10, a pair of introduction rollers S2a are provided in the second introduction seal section S2 that introduces the steel strip W into the switching area 10, and the steel strip W is introduced into the switching area 10 while preventing outside air from entering the furnace through this pair of introduction rollers S2a.

[0028] In addition, a cooling area 30 for cooling the steel strip W guided from the switching area 10 is provided downstream of the switching area 10 in the feed direction of the steel strip W, and a plating treatment equipment 40 for plating the steel strip W guided from the cooling area 30, and a discharge path 50 for discharging the steel strip W guided from the cooling area 30 without guiding it to the plating treatment equipment 40 are provided.

[0029] The plating equipment 40 is provided with a plating bath 42 containing a plating liquid 41 such as molten zinc.

[0030] Here, in the continuous heat treatment equipment for steel strips in this embodiment, when the steel strip W is introduced into the heating / cooling zone 20 through the first introduction seal section S1 as shown in Figure 1, the switching zone 10 is used as the overaging zone 12 in which the heated / cooled steel strip W is overaged.

[0031] The steel strip W introduced into the heating / cooling region 20 as described above is heated to approximately 800°C in the heating zone 21, and after the steel strip W is soaked in the soaking zone 22, the soaked steel strip W is cooled to approximately 400°C in the cooling zone 23.

[0032] Next, the steel strip W cooled in the cooling zone 23 is introduced into the overaging region 12 (switching region 10), where the steel strip W is further slowly cooled; for example, the furnace temperature is set to about 200°C, and the steel strip is slowly cooled to about 300°C, thereby performing the overaging treatment.

[0033] Here, when performing the above-mentioned overaging treatment on the steel strip W, for example, a heating device (not shown) that heats the overaging region 12 (switching region 10) can be controlled, and a fan (not shown), a gas cooler (not shown), a circulation duct (not shown), etc. can be provided in the overaging region 12 (switching region 10) to control the temperature within the overaging region 12.

[0034] The steel strip W that has been overaged in the overaging region 12 as described above is introduced into the cooling region 30 and cooled, and the cooled steel strip W is discharged through the discharge path 50 without being introduced into the plating treatment equipment 40.

[0035] At this time, the plating path (snout) 51 is immersed in the plating liquid 41 and sealed to prevent leakage of the atmosphere inside the furnace. If there is no plating liquid 41, a lid (not shown) may be attached to the bottom of the plating path 51.

[0036] Here, when the overaged steel strip W is cooled in the cooling region 30, the steel strip W is cooled so that the temperature of the steel strip W becomes 150°C or less.

[0037] At this time, the steel strip W does not pass through the second introduction seal section S2, so the pair of introduction rollers S2a come into close contact with each other and the atmosphere inside the furnace does not leak to the outside. A lid (not shown) may be attached to ensure sealing.

[0038] In this way, when the steel strip W is treated as shown in Figure 1, the steel strip W heated and cooled in the heating and cooling region 20 can be overaged in the overaging region 12.

[0039] Furthermore, in the continuous heat treatment equipment for steel strips in this embodiment, as shown in Figure 2, the heating / cooling area 20 upstream of the switching area 10 in the feed direction of the steel strip W is not used, and the steel strip W can be introduced into the switching area 10 through the second introduction seal section S2.

[0040] In this way, when the steel strip W is introduced into the switching area 10 through the second introduction seal section S2, the switching area 10 is used as a heating area 11 for heat-treating the steel strip W.

[0041] Then, the steel strip W introduced into the heating zone 11 through the second introduction seal section S2 as described above is heated to about 800°C in the heating zone 11 and soaked.

[0042] Here, when the steel strip W is thus heated to about 800° C. in the heating region 11, a heating device (not shown) that heats the heating region 11 (switching region 10) is controlled.

[0043] Depending on the circumstances, a fan (not shown), a gas cooler (not shown), a circulation duct (not shown), etc. may be provided in the heating region 11 (switching region 10) to control the temperature in the over-aging region 12. In this case, the temperature in the heating region 11 is set to be higher than the temperature in the over-aging region 12 where the above-mentioned over-aging treatment is performed.

[0044] Then, the steel strip W that has been heated and soaked in the heating area 11 as described above is introduced into the cooling area 30 to be cooled, and the cooled steel strip W is introduced into the plating treatment equipment 40 through the plating path (snout) 51.

[0045] Here, when the heated and soaked steel strip W is cooled in the cooling area 30 and introduced into the plating treatment equipment 40, the steel strip W is cooled to a temperature for plating treatment, for example, about 460°C.

[0046] The steel strip W thus cooled is then immersed and moved into a plating bath 42 containing a plating liquid 41 such as molten zinc, and the steel strip W is subjected to a plating process before being discharged.

[0047] At this time, the atmosphere inside the furnace is sealed by the plating liquid 41, and a lid 52 is attached to the exhaust path 50 to prevent the atmosphere inside the furnace from leaking.

[0048] Here, when the switching area 10 is used as the heating area 11 as described above, the steel strip W is introduced into the heating area 11 through the second introduction seal section S2 without using the heating / cooling area 20 upstream of the heating area 11 (switching area 10) in the feed direction of the steel strip W, so there is no need to guide the steel strip W into the heating / cooling area 20 and move it, and the path along which the steel strip W is moved can be shortened.

[0049] At this time, the steel strip W does not pass through the first introduction seal section S1, so the pair of introduction rollers S1a come into close contact with each other and the atmosphere inside the furnace does not leak to the outside. A lid (not shown) may be attached to ensure sealing.

[0050] Furthermore, when the steel strip W heated and soaked in the heating area 11 as described above is cooled in the cooling area 30 and then introduced into the plating treatment equipment 40, it is only necessary to cool the steel strip W to a plating treatment temperature of about 460°C, thereby reducing the time and cost required to cool the steel strip W and enabling efficient plating treatment.

[0051] Furthermore, by adding a heating / cooling zone 20 upstream of an existing continuous heat treatment facility that only has a heating zone 11, it is possible to modify the existing heating zone 11 into a switching zone 10 that can be switched between the heating zone 11 and the overaging zone 12, thereby improving the functionality of the equipment. [Explanation of symbols]

[0052] 10: Switching area 11: Heating area 12: Overaged area 20: Heating / cooling area 21: Heating zone 22:Solid temperature zone 23: Cooling zone 30: Cooling area 40: Plating equipment 41: Plating liquid 42: Plated bathtub 50:Excretion route 51: Plated Route (Snout) 52: Lid S1: First inlet seal S1a: Lead-in roller S2: Second inlet seal S2a: Lead-in roller W: Steel strip

Claims

1. This continuous heat treatment equipment for steel strips, which processes steel strips by continuously heating and cooling them, is characterized by having a switching area that can be switched between a heating area where the steel strips are heated and an overaging area where the heated and cooled steel strips are overaged.

2. 2. The continuous heat treatment equipment for steel strips according to claim 1, characterized in that a heating / cooling zone for heating and cooling the steel strip is provided upstream of the switching zone so as to be continuous with the switching zone, a first introduction seal section for introducing the steel strip into the heating / cooling zone, and a second introduction seal section for introducing the steel strip into the switching zone, a cooling zone for cooling the steel strip introduced from the switching zone is provided downstream of the switching zone, a plating treatment equipment for plating the steel strip introduced from the cooling zone, and a discharge path for discharging the steel strip introduced from the cooling zone without introducing it to the plating treatment equipment.

3. 3. A continuous heat treatment equipment for steel strips according to claim 2, characterized in that the steel strip is introduced into the heating / cooling zone through the first introduction seal section, and when the steel strip is heated and cooled in the heating / cooling zone, the switching zone is used as an overaging zone, and the steel strip heated and cooled in the heating / cooling zone is overaged in the overaging zone.

4. 4. The continuous heat treatment equipment for steel strips according to claim 3, wherein the steel strip that has been overaged in the overaging region is introduced into the cooling region to be cooled, and the cooled steel strip is discharged through a discharge path without being introduced into a plating treatment facility.

5. 3. A continuous heat treatment equipment for steel strips according to claim 2, characterized in that when the steel strip is introduced into the switching area through the second introduction seal section, the switching area is used as a heating area, and the steel strip introduced through the second introduction seal section is heat-treated in the heating area.

6. 6. The continuous heat treatment equipment for steel strips according to claim 5, wherein the steel strips that have been heat-treated in the heating zone are introduced into the cooling zone to be cooled, and the cooled steel strips are introduced into a plating treatment facility to perform plating treatment on the steel strips.

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