Continuous heat treatment equipment and method for steel strip

Abstract

To easily switch between a case where a steel strip is continuously heated and cooled for plating treatment and a case where the steel strip is continuously heated and cooled for overaging treatment, without wasting a path of an overaging zone for moving an annealed steel strip or increasing running costs, in a continuous heat treatment facility for a steel strip which continuously heats and cools the steel strip for treatment. [Solution] In a continuous heat treatment equipment for steel strips, which continuously heats and cools the steel strips W, a switching area 10 is provided that can be switched between a heating area 11 for heat-treating the steel strips and an overaging area 12 for overaging the heated and cooled steel strips.

Description

[Technical field]

[0001] The present invention is a continuous heat treatment equipment for steel strips that continuously heats and cools the steel strips. And continuous heat treatment method In particular, the present invention is characterized in that it is possible to easily switch between a case where a steel strip is continuously heated and cooled for plating treatment, and a case where 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 an example of a continuous heat treatment facility for a steel strip in which the steel strip is continuously heated and cooled, there has been disclosed a facility as disclosed in Patent Document 1 in which 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 galvanized, thereby hot-alloying the galvanized strip.

[0003] On the other hand, when the above-mentioned 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 overaging zone, a plating zone, and a final cooling zone in this order, which has a route switching mechanism that switches between a traveling route in which the steel sheet transported from the overaging 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 overaging zone is traveled to the final cooling zone without being immersed in the molten metal.

[0005] In addition, in Patent Document 3, 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 in a continuous heat treatment facility. Between the primary overaging zone and the secondary overaging zone, a galvanizing pot for hot-dip galvanizing a steel strip, a coating weight regulator, an alloying device, and a cooling device are sequentially provided, and further, a path for passing the galvanized 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. The apparatus also includes a bypass that allows the strip to pass directly from the aging zone to the secondary overaging zone, the alloying device intersection and the bypass intersection, each of which has a guide path for the steel strip inside, and are mounted adjacent to each other on a movable carriage, the movable carriage is disposed 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 to freely switch the path of the steel strip, so that the production of continuous hot-dip galvanized steel strip and the production of continuous heat-treated steel strip can be switched between each other.

[0006] Here, in the methods shown in Patent Documents 2 and 3, even when an annealed steel strip is plated, 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 overage the annealed steel strip, and the path of the overaging zone through which the annealed steel strip is moved is wasted. In addition, if the annealed steel strip is guided to the overaging zone for overaging, the temperature of the overaged steel strip will be lower than the temperature at which the plating process is performed, and it will be necessary to heat the overaged steel strip to a temperature suitable for the plating process, resulting in problems such as high running costs. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2016-180137 A [Patent Document 2] JP 2008-024981 A [Patent Document 3] JP 2002-155318 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0009] The present invention is a continuous heat treatment equipment for steel strips that continuously heats and cools the steel strips. and continuous heat treatment method The present invention aims to solve the above-mentioned problems in the field.

[0010] The present invention is a continuous heat treatment equipment for steel strips that continuously heats and cools the steel strips. And continuous heat treatment method The object of the present invention is to easily switch 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 along which the annealed steel strip moves and 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 strip according to the present invention is provided with a switching region that can switch between a heating region for heat-treating the steel strip and an overaging region for overaging the heated and cooled steel strip in the continuous heat treatment equipment for steel strip that continuously heats and cools the steel strip. 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, a first introduction seal section for introducing the steel strip into the heating / cooling zone is provided, and a second introduction seal section for introducing the steel strip into the switching zone is 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 strip 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, making it possible to easily switch between zones according to the purpose of processing 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 by 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. On the other hand, when the switching region is used as an overaging region for overaging the heated and cooled steel strip, the steel strip which has been heated and cooled to about 400°C is further slowly cooled to perform the overaging treatment, for example, the temperature in the furnace 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 according to the present invention, like 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, a first introduction seal section for introducing the steel strip into the heating / cooling zone is provided, and a second introduction seal section for introducing the steel strip into the switching zone is provided; 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. 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 portion, 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 guided to the cooling region and cooled, and the cooled steel strip can be discharged through a discharge path without being guided to 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 entry seal section, the switching zone can be used as a heating zone, and the steel strip introduced through the second entry 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 area is used as the heating area, and after the steel strip is heat-treated, the steel strip is guided to the cooling area to be cooled, and the cooled steel strip is guided to a plating treatment facility to perform plating on the steel strip. In this way, when the steel strip after the heat treatment is guided to the cooling area to be cooled and plated, the temperature to which the steel strip after the heat treatment is cooled is set to the plating treatment temperature, for example, about 460°C, and it becomes possible to prevent the steel strip from being excessively cooled in the cooling area. Effect of the Invention

[0019] Continuous heat treatment equipment for steel strips according to the present invention And continuous heat treatment method In the above-mentioned method, a switching region is provided that allows switching between a heating region for heat-treating a steel strip and an overaging region for overaging a steel strip that has been heated and cooled. By switching between this switching region for heat-treating a steel strip and an overaging region for overaging a steel strip that has been heated and cooled, it has become possible to easily switch between the heating region for heat-treating a steel strip and the overaging region for overaging a steel strip that has 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 continuously heating and cooling the steel strip for plating treatment and continuously heating and cooling the steel strip and performing overaging treatment on the heated and cooled steel strip, without wasting the path of the overaging zone along which the annealed steel strip is moved as in the conventional method and without high running costs. [Brief description of the drawings]

[0021] [Figure 1] This is a schematic explanatory diagram showing an example of a continuous heat treatment equipment and continuous heat treatment method for steel strip according to an embodiment of the present invention, in which a 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 and cooled steel strip, and shows a configuration in which the switching zone is used as an overaging zone, the steel strip heated and 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. [Diagram 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 for heat-treating the steel strip and an overaging area for overaging the heated and cooled steel strip in the above-mentioned embodiment of the continuous heat treatment equipment and continuous heat treatment method for steel strip, and shows a configuration in which the above-mentioned 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 introduced into a plating treatment equipment to perform plating treatment on the steel strip. BEST MODE FOR CARRYING OUT THEINVENTION

[0022] The following describes a continuous heat treatment equipment for steel strips according to an embodiment of the present invention. And continuous heat treatment method The present invention will be described in detail 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 embodiment, and can be modified as appropriate within the scope of the present invention.

[0023] The 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 for heat-treating a steel strip W and an overaging region 12 for overaging the heated and cooled steel strip W.

[0024] Further, a heating / cooling region 20 for heating / 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 / cooling zone 20, a pair of introduction rollers S1a is 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 / cooling zone 20 while preventing outside air from entering the furnace through this pair of introduction rollers S1a.

[0026] Within the heating / cooling region 20, the steel strip W is successively moved through a heating zone 21 for heating the steel strip W, which is disposed 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 is provided in the second introduction seal section S2, which 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 led from the switching area 10 is provided at a position 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 led from the cooling area 30, and a discharge path 50 for discharging the steel strip W led from the cooling area 30 without leading 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 region 20 through the first introduction seal section S1 as shown in Figure 1, the switching region 10 is used as an overaging region 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), and in this overaging region 12, 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), gas cooler (not shown), 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 to the cooling region 30 and cooled, and the cooled steel strip W is discharged through the discharge path 50 without being introduced to 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 in 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 its temperature becomes 150° C. or less.

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

[0038] In this manner, when the steel strip W is treated as shown in FIG. 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 zone 20 upstream of the switching zone 10 in the feed direction of the steel strip W is not used, and the steel strip W can be introduced into the switching zone 10 through the second introduction seal section S2.

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

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

[0042] Here, when the steel strip W is thus heated to about 800° C. in the heating region 11, a heating device (not shown) for heating the inside of 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), or the like may be provided in the heating region 11 (switching region 10) to control the temperature in the overaging region 12. In this case, the temperature in the heating region 11 is set to be higher than the temperature of the overaging region 12 where the above-mentioned overaging 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 to the cooling area 30 and cooled, and the cooled steel strip W is introduced to 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 equipment 40, the steel strip W is cooled to a temperature for plating, 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 heating / cooling area 20 upstream of the heating area 11 (switching area 10) in the feed direction of the steel strip W is not used, and the steel strip W is introduced into the heating area 11 through the second introduction seal section S2, 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, since the steel strip W does not pass through the first introduction seal section S1, the pair of introduction rollers S1a are in 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 processing equipment 40, it is only necessary to cool the steel strip W to about 460°C, the temperature at which the steel strip W is to be plated, thereby reducing the time and cost required to cool the steel strip W and enabling efficient plating processing.

[0051] In addition, 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 previous 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 23: Cooling Zone 30: Cooling area 40: Plating equipment 41: Plating solution 42:Plated bathtub 50:Excretion route 51: Plated route (snout) 52: Lid S1: First entry seal S1a: Introduction roller S2: Second entry seal S2a: Introduction roller W: steel strip

Claims

1. A continuous heat treatment equipment for steel strip which processes the steel strip by continuously heating and cooling the steel strip, comprising: a switching area which can be switched between a heating area for heating the steel strip and an overaging area for overaging the heated and cooled steel strip; a heating / cooling area for heating and cooling the steel strip is provided upstream of the switching area so as to be continuous with the switching area; a first introduction seal section for introducing the steel strip into the heating / cooling area and a second introduction seal section for introducing the steel strip into the switching area; a cooling area for cooling the steel strip introduced from the switching area is provided downstream of the switching area; a plating treatment equipment which plated the steel strip introduced from the cooling area; and a discharge path for discharging the steel strip introduced from the cooling area without introducing it to the plating treatment equipment.

2. A method for continuous heat treatment of steel strip, characterized in that, using the continuous heat treatment equipment for steel strip described in claim 1, 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.

3. 3. The method for continuous heat treatment of steel strip according to claim 2, characterized in that the steel strip that has been overaged in the overaging region is introduced into the cooling region and cooled, and the cooled steel strip is discharged through a discharge path without being introduced into a plating treatment facility.

4. A method for continuous heat treatment of steel strip, characterized in that, using the continuous heat treatment equipment for steel strip described in claim 1, 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.

5. 5. A method for continuous heat treatment of steel strip according to claim 4, characterized in that the steel strip heated in the heating zone 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.

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