Steel plate shape stabilization device and shape stabilization method

Abstract

The present invention provides a steel plate shape stabilization device and a shape stabilization method that can stabilize the shape of a steel plate in a continuous annealing facility, thereby suppressing meandering in the reheating zone. [Solution] The shape stabilization device 2 attached to the continuous annealing equipment 1 includes a post-cooling shape detection device 6 that detects the shape of the steel plate P at the exit side of the cooling zone 13, a processing device 61 that calculates post-cooling shape data relating to the post-cooling steel plate shape PSA based on the detection data of the post-cooling shape detection device 6, a post-cooling shape display device 62 that displays the post-cooling shape data, and a steel plate temperature adjustment device 4 that can adjust the post-cooling steel plate shape PSA by adjusting the temperatures of the front and back surfaces of the steel plate P in the cooling zone 13.

Description

Technical Field

[0001] The present invention relates to a shape stabilization device and a shape stabilization method attached to a continuous annealing facility for steel sheets.

Background Art

[0002] High-tensile steel sheets are manufactured using a continuous annealing facility including a heating zone, a cooling zone, and a re-heating zone. The continuous annealing facility continuously passes a steel sheet through the facility, heating it in the heating zone, rapidly cooling it in the cooling zone, and re-heating it to the over-aging temperature in the re-heating zone.

[0003] When the steel sheet is cooled in the cooling zone, shape defects such as warping and wavy deformation may occur in the steel sheet. Technologies for suppressing such shape defects during cooling of the steel sheet are disclosed in, for example, Patent Documents 1 to 3. In the technology disclosed in Patent Document 1, the flow rate of the cooling fluid ejected from the nozzles in the cooling zone is adjusted. In the technology disclosed in Patent Document 2, the amount of pushing-in of a leveling roll that pushes the steel sheet before cooling by the cooling zone in the thickness direction is adjusted. In the technology disclosed in Patent Document 3, the steel sheet being cooled in the cooling zone is restrained by a pair of restraint rolls.

[0004] However, the conventional technologies disclosed in Patent Documents 1 to 3 aim to make the shape of the steel sheet after cooling, which indicates the shape of the steel sheet on the outlet side of the cooling zone, into a flat shape, and do not consider the passing property of the steel sheet in the re-heating zone on the downstream side of the cooling zone. Therefore, in the conventional technology, there is a possibility that a shape that meanders in the re-heating zone is allowed for the shape of the steel sheet after cooling.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] The object of the present invention is to provide a steel plate shape stabilization device and a shape stabilization method that can stabilize the shape of a steel plate in a continuous annealing facility, thereby suppressing meandering in the reheating zone. [Means for solving the problem]

[0007] A steel plate shape stabilization device according to a first aspect of the present invention is an attachment to a continuous annealing apparatus that includes a heating zone for heating a steel plate, a cooling zone for cooling the steel plate heated in the heating zone, and a reheating zone for reheating the steel plate after cooling in the cooling zone, and is used to stabilize the shape of the steel plate. This shape stabilization device is installed between the cooling zone and the reheating zone and includes a post-cooling shape detection device for detecting the shape of the steel plate at the exit side of the cooling zone, a processing device for calculating post-cooling shape data relating to the post-cooling steel plate shape indicating the shape of the steel plate at the exit side of the cooling zone based on the detection data of the post-cooling shape detection device, a post-cooling shape display device for displaying the post-cooling shape data, and a steel plate temperature adjustment device capable of adjusting the post-cooling steel plate shape by adjusting the temperatures of the front and back surfaces of the steel plate in the cooling zone.

[0008] According to the first embodiment, the cooled steel plate shape, which indicates the shape of the steel plate at the exit side of the cooling zone of the continuous annealing equipment, can be confirmed based on the cooled steel plate shape data displayed on the cooled steel plate shape display device. This makes it possible to adjust the cooled steel plate shape in accordance with the temperature adjustment of the surface and back surfaces of the steel plate in the cooling zone by the steel plate temperature control device, while confirming whether the cooled steel plate shape is a shape that can suppress meandering in the reheating zone of the continuous annealing equipment. As a result, it is possible to stabilize the cooled steel plate shape at the exit side of the cooling zone into a shape that can suppress meandering in the reheating zone.

[0009] The steel plate shape stabilization device according to the second embodiment may further include a pre-cooling shape adjustment device that can adjust the shape of the steel plate before cooling by the cooling zone, as in the shape stabilization device according to the first embodiment.

[0010] According to the second embodiment, the pre-cooling shape adjustment device can adjust the pre-cooling steel plate shape, which indicates the shape of the steel plate at the entry side of the cooling zone that affects the post-cooling steel plate shape. In accordance with the adjustment of the pre-cooling steel plate shape by the pre-cooling shape adjustment device, it becomes possible to more reliably stabilize the post-cooling steel plate shape at the exit side of the cooling zone into a shape that can suppress meandering in the reheating zone.

[0011] A steel plate shape stabilization device according to a third embodiment may have, in the shape stabilization device according to the second embodiment, the pre-cooling shape adjustment device having at least one of the following rolls: a straightening roll installed on the entry side of the cooling zone and capable of adjusting the shape of the steel plate according to the amount of indentation applied to the steel plate in the thickness direction of the steel plate; and a guide roll that guides the steel plate that has passed through the straightening roll to the cooling zone, and capable of adjusting the shape of the steel plate that has passed through the straightening roll according to the gap between the roll surface and the pass line of the steel plate.

[0012] According to the third embodiment, at the entry side of the cooling zone, it is possible to adjust the shape of the steel sheet before cooling according to the amount of pressure the straightening rolls exert on the steel sheet. Furthermore, it is possible to adjust the shape of the steel sheet before cooling according to the gap between the guide rolls and the pass line of the steel sheet.

[0013] The steel plate shape stabilization device according to the fourth embodiment may have, in the shape stabilization device according to the first to third embodiments, a cooling zone having a surface-side injection nozzle for injecting a cooling fluid onto the surface of the steel plate and a back-side injection nozzle for injecting the cooling fluid onto the back surface of the steel plate. In this case, the steel plate temperature control device has at least one of the following devices: a flow rate adjustment device capable of adjusting the flow rate of the cooling fluid injected from each of the surface-side injection nozzle and the back-side injection nozzle, and a position adjustment device capable of adjusting the position of each of the surface-side injection nozzle and the back-side injection nozzle with respect to the pass line of the steel plate.

[0014] According to the fourth embodiment, in the cooling zone, the shape of the steel plate after cooling can be adjusted by adjusting the flow rate of the cooling fluid injected from the surface-side injection nozzles and the back-side injection nozzles using a flow rate adjustment device. Furthermore, the shape of the steel plate after cooling can be adjusted by adjusting the position of the surface-side injection nozzles and the back-side injection nozzles with respect to the pass line of the steel plate using a position adjustment device.

[0015] The steel plate shape stabilization device according to the fifth embodiment may further include a control device that controls at least one of the steel plate temperature adjustment device and the pre-cooling shape adjustment device based on the post-cooling shape data, in addition to the shape stabilization device according to the second embodiment.

[0016] According to the fifth aspect, the control device controls at least one of the steel sheet temperature adjustment device and the pre-cooling shape adjustment device based on post-cooling shape data relating to the shape of the steel sheet after cooling. As a result, the control device can automatically adjust the shape of the steel sheet after cooling, or the pre-cooling shape that affects the shape of the steel sheet after cooling, based on the post-cooling shape data. As a result, the control device can automatically stabilize the shape of the steel sheet after cooling at the exit of the cooling zone to a shape that can suppress meandering in the reheating zone.

[0017] The steel plate shape stabilization device according to the sixth embodiment may further include, in the shape stabilization device according to the fifth embodiment, a pre-cooling shape detection device installed on the entry side of the cooling zone and detecting the shape of the steel plate on the entry side of the cooling zone, and a pre-cooling shape display device that displays pre-cooling shape data relating to the shape of the steel plate on the entry side of the cooling zone based on the detection data of the pre-cooling shape detection device. In this case, the control device controls at least one of the steel plate temperature adjustment device and the pre-cooling shape adjustment device while referring to the pre-cooling shape data in addition to the post-cooling shape data.

[0018] According to the sixth embodiment, the pre-cooling steel plate shape at the entry side of the cooling zone can be confirmed based on the pre-cooling shape data displayed on the pre-cooling shape display device. The control device then controls at least one of the steel plate temperature control device and the pre-cooling shape adjustment device while referring to the pre-cooling shape data in addition to the post-cooling shape data relating to the post-cooling steel plate shape. As a result, the control device can automatically adjust the post-cooling steel plate shape, or the pre-cooling steel plate shape that affects the post-cooling steel plate shape, based on the post-cooling shape data and the pre-cooling shape data.

[0019] The steel plate shape stabilization device according to the seventh embodiment is a shape stabilization device according to the fifth or sixth embodiment, in which the control device controls at least one of the steel plate temperature control device and the pre-cooling shape adjustment device with the goal that the shape of the steel plate after cooling becomes a curved shape that protrudes to the surface side of the steel plate by a predetermined allowable amount of curvature.

[0020] According to the seventh embodiment, in the work rolls used to transport steel plates in the reheating zone, a bulge is formed in the center of the roll where the steel plate makes contact, due to thermal expansion resulting from the thermal crown phenomenon. In this case, if the shape of the steel plate as it passes through the reheating zone is asymmetrical with respect to the center line in the width direction, protruding to the back side, or flat, the steel plate will not be gripped by the bulge caused by the thermal expansion of the work rolls, causing it to meander. Therefore, the control device controls at least one of the steel plate temperature control device and the pre-cooling shape adjustment device with the goal that the shape of the steel plate after cooling at the exit side of the cooling zone will be a curved shape that protrudes to the surface side of the steel plate by a predetermined allowable amount of curvature. As a result, the shape of the steel plate as it passes through the reheating zone will be in line with the bulge caused by the thermal expansion of the work rolls in the reheating zone, making it possible to suppress the meandering of the steel plate in the reheating zone.

[0021] A method for stabilizing the shape of a steel sheet according to an eighth aspect of the present invention is a method for stabilizing the shape of a steel sheet in a continuous annealing apparatus that includes a heating zone for heating a steel sheet, a cooling zone for cooling the steel sheet heated in the heating zone, and a reheating zone for reheating the steel sheet after cooling in the cooling zone. This shape stabilization method includes: a post-cooling shape detection step for detecting the shape of the steel sheet at the exit side of the cooling zone between the cooling zone and the reheating zone; a post-cooling shape display step for displaying post-cooling shape data relating to the shape of the steel sheet at the exit side of the cooling zone based on the detection data in the post-cooling shape detection step; and a shape adjustment step for adjusting the post-cooling shape of the steel sheet based on the post-cooling shape data. In the shape adjustment step, the post-cooling shape of the steel sheet is adjusted by at least one of the following methods: a steel sheet temperature adjustment method for adjusting the temperatures of the front and back surfaces of the steel sheet in the cooling zone; and a pre-cooling shape adjustment method for adjusting the shape of the steel sheet before cooling by the cooling zone.

[0022] According to the eighth aspect, based on the post-cooling shape data displayed in the post-cooling shape display step, it is possible to confirm the shape of the steel sheet on the outlet side of the cooling zone of the continuous annealing facility, that is, the post-cooling steel sheet shape. Thereby, while confirming whether the post-cooling steel sheet shape is a shape capable of suppressing meandering in the reheating zone in the continuous annealing facility, in the shape adjustment step, it is possible to adjust the post-cooling steel sheet shape by at least one of the steel sheet temperature adjustment method and the pre-cooling shape adjustment method. As a result, it is possible to stabilize the post-cooling steel sheet shape on the outlet side of the cooling zone into a shape capable of suppressing meandering in the reheating zone.

[0023] The method for stabilizing the shape of a steel sheet according to the ninth aspect is the shape stabilization method of the eighth aspect, further including a pre-cooling shape detection step of detecting the shape of the steel sheet on the inlet side of the cooling zone, and a pre-cooling shape display step of displaying pre-cooling shape data regarding the shape of the steel sheet on the inlet side of the cooling zone based on the detection data in the pre-cooling shape detection step. In the shape adjustment step, while referring to the pre-cooling shape data in addition to the post-cooling shape data, the post-cooling steel sheet shape is adjusted by at least one of the steel sheet temperature adjustment method and the pre-cooling shape adjustment method.

[0024] According to the ninth aspect, based on the pre-cooling shape data displayed in the pre-cooling shape display step, it is possible to confirm the pre-cooling steel sheet shape on the inlet side of the cooling zone. In the shape adjustment step, while referring to the pre-cooling shape data regarding the pre-cooling steel sheet shape in addition to the post-cooling shape data regarding the post-cooling steel sheet shape, it is possible to adjust the post-cooling steel sheet shape or the pre-cooling steel sheet shape that affects the post-cooling steel sheet shape by at least one of the steel sheet temperature adjustment method and the pre-cooling shape adjustment method.

[0025] The method for stabilizing the shape of a steel sheet according to the tenth aspect is the shape stabilization method of the eighth or ninth aspect, wherein in the shape adjustment step, with the aim that the shape of the steel sheet after cooling is a warp shape protruding with a warp amount within a predetermined allowable range on the surface side of the steel sheet, the shape of the steel sheet after cooling may be adjusted by at least one of the steel sheet temperature adjustment method and the shape adjustment method before cooling.

[0026] According to the tenth aspect, in the shape adjustment step, by aiming that the shape of the steel sheet after cooling on the outlet side of the cooling zone is a warp shape protruding with a warp amount within a predetermined allowable range on the surface side of the steel sheet, it becomes possible to suppress the meandering of the steel sheet in the reheating zone.

Effects of the Invention

[0027] As described above, according to the present invention, it is possible to provide a shape stabilization device and a shape stabilization method for a steel sheet that can stabilize the shape of the steel sheet and suppress meandering in the reheating zone in a continuous annealing facility.

Brief Description of the Drawings

[0028] [Figure 1] FIG. 1 is a diagram schematically showing a continuous annealing facility to which a shape stabilization device for a steel sheet according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a diagram showing the configuration of a shape stabilization device for a steel sheet. [Figure 3] FIG. 3 is a diagram for explaining the target of the shape of the steel sheet after cooling showing the shape of the steel sheet on the outlet side of the secondary cooling zone of the continuous annealing facility. [Figure 4] FIG. 4 is a diagram for explaining the relationship between the shape of the steel sheet before cooling and the shape of the steel sheet after cooling with respect to the shape of the steel sheet. [Figure 5] FIG. 5 is a diagram for explaining the adjustment of the shape of the steel sheet by a shape adjustment device before cooling constituting the shape stabilization device. [Figure 6] FIG. 6 is a diagram for explaining the relationship between the cooling rate of the steel sheet in the secondary cooling zone of the continuous annealing facility and the shape of the steel sheet after cooling. [Figure 7]Figure 7 is a diagram illustrating the adjustment of the shape of a steel plate by a steel plate temperature control device that constitutes a shape stabilization device. [Figure 8] Figure 8 is a flowchart showing a method for stabilizing the shape of a steel plate. [Modes for carrying out the invention]

[0029] The steel plate shape stabilization device and shape stabilization method according to the present invention will be described below with reference to the drawings.

[0030] Figure 1 is a schematic diagram showing a continuous annealing apparatus 1 to which a shape stabilization device 2 of a steel sheet P according to an embodiment of the present invention is applied. The continuous annealing apparatus 1 applies various treatments such as heat treatment and cooling treatment to a steel sheet P that is passed through it continuously to produce a high-strength steel sheet called high-tensile strength steel. A high-strength steel sheet is, for example, a steel sheet containing a martensitic structure obtained by rapidly cooling an austenitic structure from a high temperature state.

[0031] The continuous annealing equipment 1 includes a heating zone 11, a soaking zone 12, a cooling zone 13, a reheating zone 14, an over-aging zone 15, and a final cooling zone 16, all arranged from the upstream to the downstream side in the direction of transport of the steel plate P.

[0032] The heating zone 11 heats the steel plate P, which is wrapped around the work roll 111 and transported, to a predetermined temperature range. The soaking zone 12 maintains the steel plate P, which is wrapped around the work roll 121 and transported after heating in the heating zone 11, at a constant temperature.

[0033] The cooling zone 13 rapidly cools the steel plate P, which is maintained at a constant temperature in the uniform zone 12. The cooling zone 13 includes a primary cooling zone 131 and a secondary cooling zone 132. The primary cooling zone 131 rapidly cools the steel plate P by injecting a cooling gas, which is a cooling fluid, onto the steel plate P. The secondary cooling zone 132 rapidly cools the steel plate P at a cooling rate of approximately 500°C / s to 1000°C / s by injecting cooling water, which is a cooling fluid, onto the steel plate P. The secondary cooling zone 132 has a surface-side injection nozzle 1321 that injects cooling water onto the surface of the steel plate P, and a back-side injection nozzle 1322 that injects cooling water onto the back surface of the steel plate P.

[0034] The reheating zone 14 reheats the steel plate P, which is wrapped around the work roll 141 and transported after cooling in the secondary cooling zone 132, to the overaging temperature. After cooling in the secondary cooling zone 132, the surface of the steel plate P that contacts the work roll 141 of the reheating zone 14 becomes the back surface of the steel plate P, and the surface opposite to the surface that contacts the work roll 141 becomes the front surface of the steel plate P. The overaging zone 15 maintains the steel plate P, which is wrapped around the work roll 151 and transported after reheating in the reheating zone 14, at the overaging temperature. The final cooling zone 16 cools the steel plate P, which is wrapped around the work roll 161 and transported, and which was maintained at the overaging temperature in the overaging zone 15, to a temperature at which it can be handled.

[0035] The steel sheet P that has passed through the final cooling zone 16 is sent to the skin pass rolling equipment 1A, recoiler equipment 1B, etc., located downstream of the continuous annealing equipment 1. The skin pass rolling equipment 1A rolls the steel sheet P sent from the continuous annealing equipment 1 to a predetermined thickness and corrects its shape. The recoiler equipment 1B winds the steel sheet P rolled in the skin pass rolling equipment 1A into a coil.

[0036] In the continuous annealing equipment 1, during the cooling of the steel plate P in the secondary cooling zone 132, a compressive stress in the width direction is formed in the steel plate P due to rapid thermal contraction at the start of cooling. This compressive stress is sufficiently smaller than the yield stress of approximately 180 MPa at 600°C if the cooling rate of the steel plate P in the secondary cooling zone 132 is approximately 1000°C / s. Therefore, the deformation of the steel plate P based on the compressive stress corresponding to the cooling in the secondary cooling zone 132 is considered to be elastic deformation. When the steel plate P buckles in each of the multiple buckling modes due to the compressive stress in the width direction, a buckling stress is applied to the steel plate P. The compressive stress in the width direction at the start of cooling in the secondary cooling zone 132 is sufficiently larger than the buckling stress in each buckling mode. Therefore, it is expected that at the start of cooling in the secondary cooling zone 132, the steel plate P deforms by buckling in various buckling modes due to the compressive stress in the width direction.

[0037] When manufacturing high-strength steel sheets containing a martensitic structure in continuous annealing equipment 1, a large amount of untransformed austenite structure exists at the start of cooling in the secondary cooling zone 132, and transformation from austenite to martensitic structure progresses during rapid cooling. In this case, in the secondary cooling zone 132, internal stress is released in the steel sheet P as the structure transforms. Therefore, the shape of the steel sheet P is maintained at the shape at the start of the transformation. That is, in the secondary cooling zone 132, the steel sheet P deforms due to buckling corresponding to the compressive stress in the width direction of the sheet at the start of cooling, and then the strain changes to plastic strain due to stress relaxation caused by the transformation from austenite to martensitic structure, and the deformation of the steel sheet P remains. Therefore, when the steel sheet P is cooled in the secondary cooling zone 132, shape defects such as warping and wavy deformation may occur in the steel sheet P.

[0038] If a shape defect occurs in the steel plate P in the secondary cooling zone 132, it is expected that the steel plate P being conveyed by the work roll 141 in the reheating zone 14 downstream of the secondary cooling zone 132 will meander. Therefore, it is necessary to stabilize the shape of the steel plate P in the continuous annealing equipment 1 so as to suppress meandering in the reheating zone 14.

[0039] Figure 2 shows the configuration of the shape stabilization device 2 for the steel sheet P. The shape stabilization device 2 is attached to the continuous annealing equipment 1 and stabilizes the shape of the steel sheet P as it passes through the continuous annealing equipment 1. Before explaining the configuration of the shape stabilization device 2, we will explain the target of the post-cooling steel sheet shape PSA, which shows the shape of the steel sheet P at the exit of the secondary cooling zone 132, with reference to Figure 3, in order to suppress meandering of the steel sheet P in the reheating zone 14.

[0040] When the steel plate P being conveyed by the work roll 141 meanders in the reheating zone 14, the CPC (Center Position Control) device connected to the work roll 141 attempts to return the steel plate P to the center of the work roll 141. Therefore, as the meandering of the steel plate P increases, the CPC control amount of the CPC device increases. This phenomenon can be used to evaluate the degree of meandering of the steel plate P based on the CPC control amount.

[0041] In the reheating zone 14, a bulge 1411 is formed in the center of the work roll 141 that contacts the steel plate P, due to thermal expansion resulting from the thermal crown phenomenon. In this case, if the cooled steel plate shape PSA at the exit side of the secondary cooling zone 132 is an asymmetrical shape with respect to the center line in the width direction, such as an S shape, a shape protruding to the back side, such as a C shape, or a flat shape, the steel plate P is less likely to be gripped by the bulge 1411 due to the thermal expansion of the work roll 141. As a result, the CPC control amount becomes large, and the steel plate P is more likely to meander. On the other hand, if the cooled steel plate shape PSA at the exit side of the secondary cooling zone 132 is a symmetrical M shape or C shape protruding to the front side, the steel plate P is more likely to be gripped by the bulge 1411 due to the thermal expansion of the work roll 141. As a result, the CPC control amount becomes small, and the steel plate P is less likely to meander.

[0042] In view of the above circumstances, the shape stabilization device 2 stabilizes the shape of the steel sheet P with the goal that the cooled steel sheet shape PSA at the exit side of the secondary cooling zone 132 will be a curved shape that protrudes toward the surface side of the steel sheet P with a predetermined allowable range TL for curvature AW. The allowable range TL for the amount of curvature AW toward the surface side of the steel sheet P is set, for example, to greater than 0 mm and less than or equal to 60 mm, taking into consideration the passability of the steel sheet P in the recoiler equipment 1B downstream of the continuous annealing equipment 1.

[0043] As shown in Figure 2, the shape stabilization device 2 comprises a pre-cooling shape adjustment device 3, a steel plate temperature adjustment device 4, a pre-cooling shape detection device 5, a pre-cooling shape display device 51, a post-cooling shape detection device 6, a processing device 61, and a post-cooling shape display device 62. The shape stabilization device 2 may also include a control device 7, which is composed of a processor capable of information processing.

[0044] The pre-cooling shape detection device 5 is installed on the inlet side of the secondary cooling zone 132 and detects the shape of the steel plate P on the inlet side of the secondary cooling zone 132. Specifically, the pre-cooling shape detection device 5 detects the warp shape in the thickness direction over the entire width direction of the steel plate P on the inlet side of the secondary cooling zone 132. The structure of the pre-cooling shape detection device 5 is not particularly limited as long as it is capable of detecting the warp shape of the steel plate P on the inlet side of the secondary cooling zone 132. For example, the pre-cooling shape detection device 5 is a camera that images the orientation of the steel plate P on the inlet side of the secondary cooling zone 132. In this case, the pre-cooling shape detection device 5 outputs an image of the steel plate P on the inlet side of the secondary cooling zone 132 as pre-cooling shape detection data D1.

[0045] The pre-cooling shape display device 51 displays pre-cooling shape data D11 relating to the shape of the steel plate P at the entrance of the secondary cooling zone 132, based on the pre-cooling shape detection data D1 output from the pre-cooling shape detection device 5. The pre-cooling shape data D11 displayed on the pre-cooling shape display device 51 can be confirmed, for example, by an operator who monitors the manufacturing status of the steel plate P in the continuous annealing equipment 1 and operates the shape stabilization device 2. If the shape stabilization device 2 is equipped with a control device 7, the pre-cooling shape data D11 may also be input to the control device 7. In the shape stabilization device 2, the operator or the control device 7 can confirm the shape of the steel plate P at the entrance of the secondary cooling zone 132 based on the pre-cooling shape data D11.

[0046] The post-cooling shape detection device 6 is installed between the secondary cooling zone 132 and the reheating zone 14 and detects the shape of the steel plate P at the exit side of the secondary cooling zone 132. Specifically, the post-cooling shape detection device 6 detects the warp shape in the thickness direction over the entire width direction of the steel plate P at the exit side of the secondary cooling zone 132. The structure of the post-cooling shape detection device 6 is not particularly limited as long as it is capable of detecting the warp shape of the steel plate P at the exit side of the secondary cooling zone 132. For example, the post-cooling shape detection device 6 can detect the warp shape of the steel plate P using the light section method. In this case, the post-cooling shape detection device 6 includes a laser oscillator that irradiates the steel plate P with a strip-shaped laser beam along the width direction of the steel plate P, and a camera having an image sensor that receives reflected light from the irradiated steel plate P and forms an image. The post-cooling shape detection device 6 may also employ a sensor that measures the profile of the steel plate P using laser light, or a sensor that measures the distance to the steel plate P using laser light. In this case, the post-cooling shape detection device 6 has a structure that includes multiple sensors arranged along the width direction of the steel plate P. The post-cooling shape detection device 6 outputs post-cooling shape detection data D2 that shows the detection result regarding the shape of the steel plate P at the exit side of the secondary cooling zone 132.

[0047] The processing unit 61 acquires the post-cooling shape detection data D2 output from the post-cooling shape detection device 6. Based on the post-cooling shape detection data D2, the processing unit 61 calculates post-cooling shape data D21 related to the post-cooling steel plate shape PSA, which indicates the curvature shape in the thickness direction over the entire width direction of the steel plate P at the exit side of the secondary cooling zone 132. The processing unit 61 outputs the calculated post-cooling shape data D21 to the post-cooling shape display device 62.

[0048] The post-cooling shape display device 62 displays the post-cooling shape data D21 output from the processing device 61 as data relating to the post-cooling steel sheet shape PSA, which indicates the shape of the steel sheet P at the exit side of the secondary cooling zone 132.

[0049] In the shape stabilization device 2, in response to the continuous passage of steel sheets P in the continuous annealing equipment 1, the following processes are repeatedly performed at a predetermined processing cycle: detection of post-cooling shape detection data D2 by the post-cooling shape detection device 6, calculation of post-cooling shape data D21 by the processing device 61, and display of post-cooling shape data D21 by the post-cooling shape display device 62. The predetermined processing cycle is set to a cycle of 30 seconds or less, and preferably to a cycle of 1 second or less. In this case, the post-cooling shape data D21 displayed on the post-cooling shape display device 62 is real-time data showing the post-cooling steel sheet shape PSA at the exit side of the secondary cooling zone 132, which changes moment by moment in response to the continuous passage of steel sheets P in the continuous annealing equipment 1. The post-cooling shape data D21 displayed on the post-cooling shape display device 62 can be confirmed, for example, by an operator. Furthermore, if the shape stabilization device 2 is equipped with a control device 7, the post-cooling shape data D21 may be input to the control device 7. In the shape stabilization device 2, the operator or control device 7 can check the cooled steel plate shape PSA, which indicates the shape of the steel plate P at the exit side of the secondary cooling zone 132, in real time based on the cooled shape data D21.

[0050] Figure 4 is a diagram illustrating the relationship between the pre-cooling steel plate shape PSB at the inlet side of the secondary cooling zone 132 and the post-cooling steel plate shape PSA at the outlet side of the secondary cooling zone 132, regarding the shape of the steel plate P. In Figure 4, the results of a simulation of the curvature shape according to the amount of curvature AW in the thickness direction over the entire width direction of the steel plate P are shown as the pre-cooling steel plate shape PSB and the post-cooling steel plate shape PSA. For the pre-cooling steel plate shape PSB and the post-cooling steel plate shape PSA, if the curvature shape protrudes on the surface side of the steel plate P, the amount of curvature AW will be a positive value greater than "0 (zero)", if the curvature shape protrudes on the back side of the steel plate P, the amount of curvature AW will be a negative value less than "0 (zero)", and if the shape is flat, the amount of curvature AW will be "0 (zero)".

[0051] As is clear from Figure 4, if the pre-cooling steel plate shape PSB is a curved shape that protrudes toward the surface side of the steel plate P, the post-cooling steel plate shape PSA will have a shape that protrudes toward the surface side in the same direction as the pre-cooling steel plate shape PSB, and the amount of curvature AW will be greater than that of the pre-cooling steel plate shape PSB. On the other hand, if the pre-cooling steel plate shape PSB is flat, the post-cooling steel plate shape PSA will have a shape that has a portion that protrudes toward the surface side of the steel plate P and a portion that protrudes toward the back side of the steel plate P. Considering the relationship between the pre-cooling steel plate shape PSB and the post-cooling steel plate shape PSA shown in Figure 4, it can be seen that the pre-cooling steel plate shape PSB affects the post-cooling steel plate shape PSA. Furthermore, as previously mentioned, considering that the post-cooling steel plate shape PSA is prone to meandering in the reheating zone 14 when it is a curved shape that protrudes toward the back side of the steel plate P, it is clear that the pre-cooling steel plate shape PSB should avoid being flat and aim to be a curved shape that protrudes toward the surface side of the steel plate P. The pre-cooling steel sheet shape PSB, which affects the post-cooling steel sheet shape PSA, becomes a curved shape that protrudes from the surface side of the steel sheet P. As a result, the post-cooling steel sheet shape PSA becomes a curved shape that protrudes from the surface side of the steel sheet P, which is the target shape described above, with a predetermined allowable range TL for the amount of curvature AW.

[0052] The pre-cooling shape adjustment device 3 can adjust the pre-cooling steel plate shape PSB, which indicates the shape of the steel plate P before cooling by the secondary cooling zone 132. Depending on the adjustment of the pre-cooling steel plate shape PSB by the pre-cooling shape adjustment device 3, it is possible to stabilize the post-cooling steel plate shape PSA into a shape that can suppress meandering in the reheating zone 14.

[0053] Figure 5 is a diagram illustrating the adjustment of the shape of the steel plate P by the pre-cooling shape adjustment device 3, which constitutes the shape stabilization device 2. The pre-cooling shape adjustment device 3 includes a first straightening roll 311, a second straightening roll 312, and a third straightening roll 313, which are multiple straightening rolls installed on the entry side of the secondary cooling zone 132, and a first guide roll 321 and a second guide roll 322, which are installed between each straightening roll and the secondary cooling zone 132, directly in front of the secondary cooling zone 132.

[0054] The first straightening roll 311, the second straightening roll 312, and the third straightening roll 313 are installed in a row from the upstream side toward the secondary cooling zone 132 to the downstream side toward the secondary cooling zone 132 at the entrance side of the secondary cooling zone 132. The first straightening roll 311 is a straightening roll that pushes the steel plate P in the thickness direction from the surface side of the steel plate P. The second straightening roll 312 is a straightening roll located downstream of the first straightening roll 311 that pushes the steel plate P in the thickness direction from the back side of the steel plate P. The third straightening roll 313 is a straightening roll located downstream of the second straightening roll 312 that pushes the steel plate P in the thickness direction from the surface side of the steel plate P.

[0055] The steel plate P, which was flat at the entry side of the first straightening roll 311, is pushed in from the surface side by the first straightening roll 311 and pushed in from the back side by the second straightening roll 312. As a result, at the exit side of the second straightening roll 312, the steel plate P is bent in the longitudinal direction perpendicular to the plate width direction. However, since the steel plate P is continuous in the longitudinal direction, the shape of the steel plate P bent in the longitudinal direction is not maintained, and at the exit side of the third straightening roll 313, it becomes curved in the plate width direction. In other words, the pre-cooling shape PSB of the steel plate P that has passed through the first straightening roll 311, the second straightening roll 312, and the third straightening roll 313 is a curved shape that protrudes towards the surface side along the entire width direction of the steel plate P.

[0056] As the amount of indentation of the first straightening roll 311 and the second straightening roll 312 is increased, the plastic deformation rate of the steel sheet P increases, and the amount of curvature AW of the steel sheet P increases. By adjusting the amount of indentation of the third straightening roll 313, the amount of curvature AW formed by the first straightening roll 311 and the second straightening roll 312 can be adjusted by bending the steel sheet P in the opposite direction. Utilizing this phenomenon, the first straightening roll 311, the second straightening roll 312, and the third straightening roll 313 can adjust the pre-cooled steel sheet shape PSB, which affects the post-cooled steel sheet shape PSA, with the goal of creating a curved shape that protrudes towards the surface of the steel sheet P, depending on the amount of indentation applied to the steel sheet P.

[0057] The first guide roll 321 and the second guide roll 322 are rolls that guide the steel plate P, which has passed through the first straightening roll 311, the second straightening roll 312, and the third straightening roll 313, to the secondary cooling zone 132. The first guide roll 321 is installed on the surface side of the steel plate P just before the secondary cooling zone 132. The second guide roll 322 is installed on the back side of the steel plate P just before the secondary cooling zone 132.

[0058] The first guide roll 321 and the second guide roll 322 can adjust the pre-cooling steel sheet shape PSB of the steel sheet P after it has passed through the first straightening roll 311, the second straightening roll 312, and the third straightening roll 313, according to the gap GP between the surface of each roll and the pass line PL of the steel sheet P. The first guide roll 321 and the second guide roll 322 can reduce the amount of warping AW of the steel sheet P as the gap GP with respect to the pass line PL narrows. Figure 5 illustrates the results of a simulation of the relationship between the gap GP of the first guide roll 321 and the second guide roll 322 and the post-cooling steel sheet shape PSA. From Figure 5, it can be seen that the amount of warping AW of the steel sheet P decreases as the gap GP narrows in the order of "100 mm", "30 mm", and "5 mm" compared to the state in which the first guide roll 321 and the second guide roll 322 are open. The first guide roll 321 and the second guide roll 322 can adjust the pre-cooled steel sheet shape PSB, which affects the post-cooled steel sheet shape PSA, with the goal of creating a curved shape that protrudes towards the surface side of the steel sheet P, depending on the gap GP with respect to the pass line PL.

[0059] Figure 6 is a diagram illustrating the relationship between the cooling rate of the steel sheet P in the secondary cooling zone 132 of the continuous annealing equipment 1 and the shape of the steel sheet PSA after cooling. Figure 6 illustrates the results of a simulation of the change in the amount of warpage AW of the steel sheet P when the cooling rate of the steel sheet P in the secondary cooling zone 132 is changed in the order of "681°C / s", "1006°C / s", and "1129°C / s". When the cooling rate is "681°C / s", the steel sheet P has a C-shaped warpage with one protrusion on the surface side. When the cooling rate is increased to "1006°C / s", the warpage changes to an M-shaped warpage with two protrusions on the surface side, and the amount of warpage AW increases. When the cooling rate is further increased to "1129°C / s", the warpage shape of the steel sheet P remains M-shaped, but the amount of warpage AW increases even further.

[0060] Considering the relationship between the cooling rate of the steel sheet P in the secondary cooling zone 132 and the shape PSA of the steel sheet after cooling, as shown in Figure 6, it can be seen that the cooling rate of the steel sheet P in the secondary cooling zone 132 affects the shape PSA of the steel sheet after cooling. The cooling rate of the steel sheet P in the secondary cooling zone 132 can be adjusted by adjusting the temperature of the surface and back surfaces of the steel sheet P in the secondary cooling zone 132. Furthermore, the cooling rate of the steel sheet P can also be adjusted by adjusting the temperature of the cooling water injected from the surface-side injection nozzle 1321 and the back-side injection nozzle 1322 in the secondary cooling zone 132.

[0061] Figure 7 is a diagram illustrating the adjustment of the shape of the steel plate P by the steel plate temperature control device 4, which constitutes the shape stabilization device 2. The steel plate temperature control device 4 can adjust the cooled steel plate shape PSA at the exit of the secondary cooling zone 132 by adjusting the temperature of the front and back surfaces of the steel plate P in the secondary cooling zone 132. The steel plate temperature control device 4 adjusts the cooled steel plate shape PSA with the goal of making the cooled steel plate shape PSA a curved shape that protrudes from the front surface of the steel plate P with a predetermined allowable curvature amount AW within TL.

[0062] The steel plate temperature control device 4 adjusts the temperature of the surface of the steel plate P in the secondary cooling zone 132 to be lower than the temperature of the back surface, thereby reducing the amount of warping AW toward the surface side as the thermal contraction of the surface of the steel plate P becomes greater than that of the back surface. Furthermore, the steel plate temperature control device 4 adjusts the temperature of the back surface of the steel plate P in the secondary cooling zone 132 to be lower than the temperature of the surface, thereby increasing the amount of warping AW toward the surface side as the thermal contraction of the back surface of the steel plate P becomes greater than that of the surface.

[0063] As described above, in the shape stabilization device 2, the operator or control device 7 can check the cooled steel sheet shape PSA at the exit of the secondary cooling zone 132 of the continuous annealing equipment 1 based on the cooled shape data D21 displayed in the cooled shape display device 62. This makes it possible to adjust the cooled steel sheet shape PSA in accordance with the temperature adjustment of the surface and back surfaces of the steel sheet P in the secondary cooling zone 132 by the steel sheet temperature adjustment device 4, while confirming whether the cooled steel sheet shape PSA is a shape that can suppress meandering in the reheating zone 14 in the continuous annealing equipment 1. As a result, it is possible to stabilize the cooled steel sheet shape PSA at the exit of the secondary cooling zone 132 to a shape that can suppress meandering in the reheating zone 14.

[0064] The steel plate temperature control device 4 has at least one of the flow rate adjustment device 41 and the position adjustment device 42. In this embodiment, the steel plate temperature control device 4 has both the flow rate adjustment device 41 and the position adjustment device 42.

[0065] The flow rate adjustment device 41 is connected to the pump 411 and can adjust the flow rate of the cooling water injected from the front-side injection nozzle 1321 and the back-side injection nozzle 1322, respectively. The flow rate of the cooling water injected from the front-side injection nozzle 1321 and the back-side injection nozzle 1322 can be measured using a pressure gauge 412 or a flow meter 413.

[0066] The flow rate adjustment device 41 can reduce the amount of warping AW toward the surface side of the steel plate P as the thermal contraction of the surface side becomes greater than that of the back side, by reducing the water pressure ratio WPR, which is the ratio of the water pressure of the back side injection nozzle 1322 to the water pressure of the front side injection nozzle 1321, that is, by adjusting the flow rate of the back side injection nozzle 1322 to be smaller than that of the front side injection nozzle 1321. Conversely, the flow rate adjustment device 41 can increase the amount of warping AW toward the surface side of the steel plate P as the thermal contraction of the back side becomes greater than that of the surface, by increasing the water pressure ratio WPR, that is, by adjusting the flow rate of the back side injection nozzle 1322 to be larger than that of the front side injection nozzle 1321.

[0067] Figure 7 illustrates the measured values ​​of the change in the amount of warpage AW in the cooled steel sheet shape PSA when the water pressure ratio WPR is changed in the order of "1.15", "1.39", "1.55", and "2.91". When the water pressure ratio WPR is "1.15", the steel sheet P has a warped shape with a protrusion on the back side. When the water pressure ratio WPR is "1.39", the flow rate of the back-side injection nozzle 1322 becomes larger than the flow rate of the front-side injection nozzle 1321, and the warped shape changes to one with a protrusion on the front side. As the water pressure ratio WPR increases in the order of "1.39", "1.55", and "2.91", the warped shape of the steel sheet P maintains the shape with a protrusion on the front side, while the amount of warpage AW increases. From the above, the flow rate adjustment device 41 can adjust the cooled steel sheet shape PSA by adjusting the flow rate of the cooling water injected from the front-side injection nozzle 1321 and the back-side injection nozzle 1322, respectively.

[0068] The position adjustment device 42 can adjust the position of the front-side injection nozzle 1321 and the back-side injection nozzle 1322 relative to the pass line PL of the steel plate P. By adjusting the position of the back-side injection nozzle 1322 to be further away from the front-side injection nozzle 1321 relative to the pass line PL of the steel plate P, the position adjustment device 42 can reduce the water pressure ratio WPR. This allows the position adjustment device 42 to reduce the amount of warping AW toward the front side as the thermal shrinkage of the front surface of the steel plate P becomes greater than that of the back surface. Conversely, by adjusting the position of the back-side injection nozzle 1322 to be closer to the front-side injection nozzle 1321 relative to the pass line PL of the steel plate P, the position adjustment device 42 can increase the water pressure ratio WPR. This allows the position adjustment device 42 to increase the amount of warping AW toward the front side as the thermal shrinkage of the back surface of the steel plate P becomes greater than that of the front surface. Based on the above, the position adjustment device 42 can adjust the shape PSA of the steel plate after cooling by adjusting the position of the surface-side injection nozzle 1321 and the back-side injection nozzle 1322 with respect to the pass line PL of the steel plate P.

[0069] If the shape stabilization device 2 includes a control device 7, the control device 7 controls at least one of the steel sheet temperature adjustment device 4 and the pre-cooling shape adjustment device 3 based on the post-cooling shape data D21 relating to the post-cooling steel sheet shape PSA displayed in the post-cooling shape display device 62. As a result, the control device 7 can automatically adjust the post-cooling steel sheet shape PSA, or the pre-cooling steel sheet shape PSB that affects the post-cooling steel sheet shape PSA, based on the post-cooling shape data D21. Consequently, the control device 7 can automatically stabilize the post-cooling steel sheet shape PSA at the exit side of the secondary cooling zone 132 to a shape that can suppress meandering in the reheating zone 14.

[0070] Furthermore, when the control device 7 controls at least one of the steel sheet temperature control device 4 and the pre-cooling shape adjustment device 3, it may refer to the pre-cooling shape data D11 related to the pre-cooling steel sheet shape PSB displayed on the pre-cooling shape display device 51. In other words, the control device 7 controls at least one of the steel sheet temperature control device 4 and the pre-cooling shape adjustment device 3 while referring to the pre-cooling shape data D11 in addition to the post-cooling shape data D21. As a result, the control device 7 can automatically adjust the post-cooling steel sheet shape PSA, or the pre-cooling steel sheet shape PSB that affects the post-cooling steel sheet shape PSA, based on the post-cooling shape data D21 and the pre-cooling shape data D11.

[0071] Furthermore, the control device 7 controls at least one of the steel sheet temperature control device 4 and the pre-cooling shape adjustment device 3 with the goal that the post-cooling steel sheet shape PSA at the exit side of the secondary cooling zone 132 will be a curved shape that protrudes on the surface side of the steel sheet P with a predetermined allowable curve amount AW of TL. As a result, the shape of the steel sheet P as it passes through the reheating zone 14 will be in line with the bulge 1411 caused by the thermal expansion of the work roll 141 in the reheating zone 14, thereby more reliably suppressing the meandering of the steel sheet P in the reheating zone 14.

[0072] Figure 8 is a flowchart illustrating a method for stabilizing the shape of a steel plate P. The method for stabilizing the shape of a steel plate P can be carried out using a shape stabilization device 2. The method for stabilizing the shape of a steel plate P is a method for stabilizing the shape of a steel plate P in a continuous annealing facility 1. The shape stabilization method includes a pre-cooling shape detection step S1, a pre-cooling shape display step S2, a post-cooling shape detection step S3, a post-cooling shape display step S4, and a shape adjustment step S5.

[0073] In the pre-cooling shape detection step S1, the pre-cooling shape detection device 5 detects the shape of the steel plate P at the entrance side of the secondary cooling zone 132 and outputs pre-cooling shape detection data D1 showing the detection result. In the pre-cooling shape display step S2, the pre-cooling shape display device 51 displays pre-cooling shape data D11 related to the pre-cooling steel plate shape PSB, which shows the shape of the steel plate P at the entrance side of the secondary cooling zone 132, based on the pre-cooling shape detection data D1.

[0074] In the post-cooling shape detection step S3, the post-cooling shape detection device 6 detects the shape of the steel plate P at the exit side of the secondary cooling zone 132 and outputs post-cooling shape detection data D2 showing the detection result. When the post-cooling shape detection device 6 outputs the post-cooling shape detection data D2, the processing device 61 calculates post-cooling shape data D21 related to the post-cooling steel plate shape PSA, which shows the shape of the steel plate P at the exit side of the secondary cooling zone 132, based on the post-cooling shape detection data D2. In the post-cooling shape display step S4, the post-cooling shape display device 62 displays the post-cooling shape data D21 calculated by the processing device 61 based on the post-cooling shape detection data D2.

[0075] The shape adjustment process S5 is performed by an operator or a control device 7. The following describes the case where an operator performs the shape adjustment process S5.

[0076] In the shape adjustment process S5, the operator adjusts the cooled steel sheet shape PSA based on the cooled shape data D21 displayed on the cooled shape display device 62. Specifically, the operator adjusts the cooled steel sheet shape PSA by at least one of the following methods: a steel sheet temperature adjustment method that adjusts the temperature of the front and back surfaces of the steel sheet P in the secondary cooling zone 132 by operating the steel sheet temperature adjustment device 4, and a pre-cooling shape adjustment method that adjusts the pre-cooled steel sheet shape PSB of the steel sheet P before cooling by the secondary cooling zone 132 by operating the pre-cooled shape adjustment device 3.

[0077] The operator can confirm the cooled steel sheet shape PSA at the exit of the secondary cooling zone 132 of the continuous annealing equipment 1 based on the cooled shape data D21 displayed on the cooled shape display device 62. This allows the operator to adjust the cooled steel sheet shape PSA in the shape adjustment process S5 using at least one of the steel sheet temperature adjustment method and the pre-cooling shape adjustment method, while confirming whether the cooled steel sheet shape PSA is a shape that can suppress meandering in the reheating zone 14 of the continuous annealing equipment 1. As a result, it becomes possible to stabilize the cooled steel sheet shape PSA at the exit of the secondary cooling zone 132 into a shape that can suppress meandering in the reheating zone 14.

[0078] In the shape adjustment process S5, the operator may adjust the post-cooled steel sheet shape PSA by at least one of the steel sheet temperature adjustment method and the pre-cooled shape adjustment method, while referring to the pre-cooled shape data D11 displayed on the pre-cooled shape display device 51 in addition to the post-cooled shape data D21. In this case, the operator can adjust the post-cooled steel sheet shape PSA or the pre-cooled steel sheet shape PSB that affects the post-cooled steel sheet shape PSA.

[0079] Furthermore, in the shape adjustment process S5, the operator may adjust the cooled steel sheet shape PSA by at least one of the steel sheet temperature adjustment method and the pre-cooling shape adjustment method, with the goal that the cooled steel sheet shape PSA will be a curved shape that protrudes from the surface side of the steel sheet P with a predetermined allowable range TL of curvature AW. In this case, by aiming that the cooled steel sheet shape PSA at the exit side of the secondary cooling zone 132 will be a curved shape that protrudes from the surface side of the steel sheet P with a predetermined allowable range TL of curvature AW, the operator can suppress meandering of the steel sheet P in the reheating zone 14.

[0080] If the continuous annealing equipment 1 continues to operate, the following steps will be repeated: pre-cooling shape detection step S1, pre-cooling shape display step S2, post-cooling shape detection step S3, post-cooling shape display step S4, and shape adjustment step S5. [Explanation of symbols]

[0081] 1. Continuous annealing equipment 11. Heating Zone 13 Cooling Zone 131 Primary Cooling Zone 132 Secondary Cooling Zone 1321 Surface-side spray nozzle 1322 Rear side spray nozzle 14 Reheating Zone 2 Shape stabilizing device 3 Shape adjustment device before cooling 311, 312, 313 Orthodontic Rolls 321,322 Guide Roll 4 Steel plate temperature adjustment device 41 Flow rate adjustment device 42 Position adjustment device 5. Pre-cooling shape detection device 51 Shape display device before cooling 6. Shape detection device after cooling 61 Processing Unit 62 Shape display device after cooling 7 Control device

Claims

1. A steel plate shape stabilization device attached to a continuous annealing apparatus, which includes a heating zone for heating a steel plate, a cooling zone for cooling the steel plate heated in the heating zone, and a reheating zone for reheating the steel plate after cooling in the cooling zone, for stabilizing the shape of the steel plate, A post-cooling shape detection device is installed between the cooling zone and the reheating zone and detects the shape of the steel plate at the exit side of the cooling zone. A processing device that calculates post-cooling shape data relating to the shape of the steel plate after cooling, which shows the shape of the steel plate at the exit side of the cooling zone, based on the detection data of the post-cooling shape detection device, A cooling shape display device that displays the cooling shape data, A steel plate shape stabilization device comprising a steel plate temperature adjustment device capable of adjusting the shape of the steel plate after cooling by adjusting the temperature of the front and back surfaces of the steel plate in the cooling zone.

2. The steel plate shape stabilization device according to claim 1, further comprising a pre-cooling shape adjustment device capable of adjusting the shape of the steel plate before cooling by the cooling zone.

3. The pre-cooling shape adjustment device is A straightening roll is installed on the entry side of the cooling zone and is capable of adjusting the shape of the steel plate according to the amount of pressure applied to push the steel plate in the thickness direction of the steel plate, The steel plate shape stabilization device according to claim 2, comprising at least one of the following rolls: a roll for guiding the steel plate that has passed through the straightening roll to the cooling zone, and a guide roll capable of adjusting the shape of the steel plate that has passed through the straightening roll according to the gap between the roll surface and the pass line of the steel plate.

4. The cooling zone has a surface-side injection nozzle for injecting cooling fluid onto the surface of the steel plate, and a back-side injection nozzle for injecting the cooling fluid onto the back surface of the steel plate. The steel plate temperature control device is A flow rate adjustment device capable of adjusting the flow rate of the cooling fluid injected from each of the surface-side injection nozzles and the back-side injection nozzles, The steel plate shape stabilization device according to claim 1, further comprising at least one of the following devices: a position adjustment device capable of adjusting the position of each of the surface-side injection nozzle and the back-side injection nozzle with respect to the pass line of the steel plate.

5. The steel plate shape stabilization device according to claim 2, further comprising a control device that controls at least one of the steel plate temperature adjustment device and the pre-cooling shape adjustment device based on the post-cooling shape data.

6. A pre-cooling shape detection device is installed on the entry side of the cooling zone and detects the shape of the steel plate on the entry side of the cooling zone. The system further includes a pre-cooling shape display device that displays pre-cooling shape data relating to the shape of the steel plate at the entrance side of the cooling zone based on the detection data of the pre-cooling shape detection device, The steel plate shape stabilization device according to claim 5, wherein the control device controls at least one of the steel plate temperature adjustment device and the pre-cooling shape adjustment device while referring to the pre-cooling shape data in addition to the post-cooling shape data.

7. The steel plate shape stabilization device according to claim 5 or 6, wherein the control device controls at least one of the steel plate temperature control device and the pre-cooling shape adjustment device with the goal that the shape of the steel plate after cooling will be a curved shape that protrudes to the surface side of the steel plate by a predetermined allowable amount of curvature.

8. A method for stabilizing the shape of a steel plate in a continuous annealing apparatus that includes a heating zone for heating a steel plate, a cooling zone for cooling the steel plate heated in the heating zone, and a reheating zone for reheating the steel plate after cooling in the cooling zone, wherein the shape of the steel plate is stabilized. Between the cooling zone and the reheating zone, a post-cooling shape detection step is performed to detect the shape of the steel plate at the exit side of the cooling zone, A post-cooling shape display step, which displays post-cooling shape data relating to the shape of the steel plate after cooling, showing the shape of the steel plate at the exit side of the cooling zone, based on the detection data in the post-cooling shape detection step, The process includes a shape adjustment step to adjust the shape of the cooled steel sheet based on the cooled shape data, A method for stabilizing the shape of a steel plate, wherein the shape adjustment step involves adjusting the shape of the steel plate after cooling by at least one of the following methods: a steel plate temperature adjustment method for adjusting the temperature of the front and back surfaces of the steel plate in the cooling zone, and a pre-cooling shape adjustment method for adjusting the shape of the steel plate before cooling by the cooling zone.

9. A pre-cooling shape detection step for detecting the shape of the steel plate at the entry side of the cooling zone, The process further includes a pre-cooling shape display step that displays pre-cooling shape data relating to the shape of the steel plate at the entry side of the cooling zone, based on the detection data from the pre-cooling shape detection step, The method for stabilizing the shape of a steel plate according to claim 8, wherein in the shape adjustment step, the shape of the steel plate after cooling is adjusted by at least one of the steel plate temperature adjustment method and the pre-cooling shape adjustment method, while referring to the pre-cooling shape data in addition to the post-cooling shape data.

10. The method for stabilizing the shape of a steel plate according to claim 8 or 9, wherein the shape adjustment step aims to adjust the shape of the cooled steel plate by at least one of the steel plate temperature adjustment method and the pre-cooling shape adjustment method, so that the shape of the cooled steel plate becomes a curved shape that protrudes to the surface side of the steel plate by a predetermined allowable amount of curvature.

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