Quenching device and continuous annealing apparatus, and quenching method, method for manufacturing steel sheet, and method for manufacturing plated steel sheet

Abstract

Provided is a quenching device and a continuous annealing apparatus, and a quenching method, a steel sheet manufacturing method, and a plated steel sheet manufacturing method, which can suppress warping of a metal sheet after quenching even when the metal sheet has already warped before quenching. The quenching device 1 includes a cooling device 10 that cools a metal sheet S using a cooling fluid to perform quenching; shape correction rollers 30 that are respectively provided on each of a surface side and a back side of the metal sheet S and press the metal sheet S before quenching in a thickness direction of the metal sheet S; and a press control device 40 that controls the pressing of the shape correction rollers 30 based on a shape of the metal sheet S before quenching.

Description

Technical Field

[0001] This invention relates to a quenching apparatus and a continuous annealing equipment for quenching metal plates while continuously passing them through the plate, as well as quenching methods, methods for manufacturing steel plates, and methods for manufacturing coated steel plates. Background Technology

[0002] In the manufacturing of metal sheets, such as steel sheets, continuous annealing equipment, which continuously passes the metal sheet through the furnace while annealing, produces the material by heating and then cooling the sheet, promoting phase transformation, and so on. In recent years, in the automotive industry, the demand for thin-walled high-tensile steel sheets (high-tensile steel) has been increasing, aiming to balance vehicle weight reduction and crash safety.

[0003] In the manufacture of high-tensile steel sheets, rapid cooling techniques become crucial. One of the fastest cooling methods is water quenching. In water quenching, the heated steel sheet is immersed in water while cooling water is sprayed onto the sheet through quenching nozzles positioned in the water, thus quenching the steel. However, during quenching, problems such as warping and wavy deformation can occur, resulting in shape defects in the steel sheet.

[0004] To prevent poor shape during quenching of steel plates, various methods have been proposed (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses a structure in which cooling water jet nozzles are arranged in multiple stages in the immersion water used to cool the heated strip, and the water collection seats for each nozzle are separately arranged relative to the direction of strip travel. This prevents lateral flow that occurs in conventional multi-stage slit nozzles and provides uniform cooling in the width direction of the plate.

[0005] In addition, Patent Document 2 discloses a method of installing tension rollers before and after the quenching section in order to suppress the wavy deformation of the metal plate generated during quenching in a continuous annealing furnace, which is a tension changing mechanism capable of changing the tension applied to the steel plate during the quenching process.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 59-153843

[0009] Patent Document 2: Japanese Patent Application Publication No. 2011-184773 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, in the method disclosed in Patent Document 1, if the metal plate is already warped before quenching, the shape correction effect is insufficient. Furthermore, in the method disclosed in Patent Document 2, the metal plate may break due to the large tension applied to it at high temperatures. Additionally, a large thermal bulge is generated on the tension roller in front of the quenching section that contacts the high-temperature metal plate, resulting in uneven contact between the tension roller and the metal plate in the width direction. This causes warping and defects on the metal plate, thus failing to improve the shape of the metal plate.

[0012] This invention was made to solve such a problem, and its purpose is to provide a quenching apparatus and a continuous annealing equipment that can suppress warping of the quenched metal plate even when warping already exists in the metal plate before quenching, as well as a quenching method, a method for manufacturing steel plates, and a method for manufacturing coated steel plates.

[0013] Methods for solving problems

[0014] [1] A quenching apparatus for cooling a metal plate, the quenching apparatus comprising: a cooling device for quenching the metal plate by cooling it with a cooling fluid; shape straightening rollers respectively disposed on the surface side and the back side of the metal plate for pressing the metal plate before quenching in the thickness direction of the metal plate; and a pressing control device for setting the pressing amount of the shape straightening rollers based on the shape of the metal plate before quenching.

[0015] [2] The quenching apparatus as described in [1], wherein the aforementioned pressing control device is controlled in the following manner: when the aforementioned metal plate before quenching is a warped shape protruding to the surface side, the aforementioned shape correction roller on the surface side of the aforementioned metal plate is pressed in; when the aforementioned metal plate before quenching is a warped shape protruding to the back side, the aforementioned shape correction roller on the back side of the aforementioned metal plate is pressed in.

[0016] [3] The quenching apparatus as described in [1] or [2] further comprises a shape measuring device for measuring the shape of the aforementioned metal plate before quenching.

[0017] [4] The quenching apparatus as described in [3], wherein the aforementioned shape measuring device has the function of measuring the warp amount of the aforementioned metal plate, and the aforementioned pressing control device controls the pressing by setting the measured warp amount of the aforementioned metal plate as the pressing amount and pressing the aforementioned shape correcting roller in.

[0018] [5] The quenching apparatus as described in any one of [1] to [4], wherein the distance between the central axes of the aforementioned shape-correcting rollers on the surface side and the back side is set to be more than 100 mm and less than 1000 mm, and the distance between the cooling start point of the aforementioned cooling apparatus and the aforementioned shape-correcting roller is less than 500 mm.

[0019] [6] A continuous annealing apparatus, wherein the outlet side of the heat exchanger is equipped with any of the quenching devices described in any one of [1] to [5].

[0020] [7] Quenching method, which is a quenching method that uses a cooling fluid to cool a metal plate for quenching, wherein the shape of the aforementioned metal plate before quenching is determined, and based on the determined shape of the aforementioned metal plate, the aforementioned metal plate is pressed in the thickness direction by shape correction rollers respectively provided on the surface side and the back side of the aforementioned metal plate.

[0021] [8] In the quenching method described in [7], when pressing the aforementioned metal plate in the thickness direction, if the aforementioned metal plate before quenching has a warped shape protruding to the surface side, the aforementioned shape correction roller on the surface side of the aforementioned metal plate is pressed in; if the aforementioned metal plate before quenching has a warped shape protruding to the back side, the aforementioned shape correction roller on the back side of the aforementioned metal plate is pressed in.

[0022] [9] In the quenching method described in [8], when the shape of the aforementioned metal plate is determined, the warping direction and warping amount of the aforementioned metal plate are determined, and when the aforementioned metal plate is pressed in, the warping amount of the aforementioned metal plate is used as the pressing amount to press in the aforementioned shape correction roller.

[0023]

[10] A method for manufacturing a steel plate, wherein the steel plate, which is the aforementioned metal plate, is quenched by any one of the quenching methods described in [7] to [9].

[0024]

[11] A method for manufacturing a coated steel sheet, wherein a cold-rolled steel sheet manufactured by the steel sheet manufacturing method described in

[10] is subjected to a coating treatment.

[0025]

[12] The method for manufacturing coated steel sheet as described in

[11] , wherein the aforementioned coating treatment is any one of hot galvanizing, electro-galvanizing and alloying hot galvanizing.

[0026] Invention Effects

[0027] According to the present invention, the metal sheet before quenching is pressed in the thickness direction according to the shape of the metal sheet. Therefore, when quenching is performed while the metal sheet is continuously passed through the sheet, warping of the quenched metal sheet can be suppressed even if the metal sheet before quenching is warped. Attached Figure Description

[0028] [ Figure 1 [Illustration] is a schematic diagram illustrating a quenching apparatus according to an embodiment of the present invention.

[0029] [ Figure 2 [Illustration] is a schematic diagram showing the shape-correcting roller pressing a metal sheet into the metal sheet.

[0030] [ Figure 3 [Illustration] is a schematic diagram showing the shape-correcting roller pressing a metal sheet into the metal sheet.

[0031] [ Figure 4 [Illustration] is a schematic diagram illustrating an example of the definition of the warping amount of a metal plate. Detailed Implementation

[0032] Embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a schematic diagram illustrating an example of a quenching apparatus according to an embodiment of the present invention. It should be noted that... Figure 1 The quenching apparatus 1 is an apparatus for quenching steel, for example, as a metal plate S, and is used as a cooling device on the outlet side of the heat exchanger of a continuous annealing equipment such as a continuous annealing furnace. Figure 1 The quenching apparatus 1 includes a cooling device 10 for cooling the metal plate S. The cooling device 10 uses a refrigerant CF to cool the metal plate and includes a cooling tank 11 for storing the refrigerant CF and multiple spray nozzles 12 disposed in the cooling tank 11 for spraying the refrigerant CF onto the surface and back of the metal plate S.

[0033] Water, used as a refrigerant CF, is stored in the cooling tank 11. For example, a metal plate S is immersed in the cooling tank 11 from its upper surface toward the through-plate direction. The refrigerant CF in the cooling tank 11 is maintained at a suitable quenching water temperature. For example, the water temperature in the cooling tank 11 is preferably greater than 0°C and less than 50°C, and particularly preferably more than 10°C and less than 40°C. A portion of the refrigerant CF in the cooling tank 11 is sent to an external cooling tower or other cooling equipment and cooled. The cooled refrigerant CF is then returned to the cooling tank 11, thereby preventing the water temperature in the cooling tank 11 from rising. It should be noted that a submerged roller 2 is provided in the cooling tank 11 to change the through-plate direction of the metal plate S. The through-plate direction refers to the conveying direction of the metal plate S.

[0034] Multiple nozzles 12 are arranged on both sides of the metal plate along the through-plate direction of the metal plate S. It should be noted that the nozzles 12 are preferably symmetrically arranged on the front and back sides of the metal plate S, and slit nozzles are preferred to obtain a more uniform cooling capacity in the width direction. Therefore, the metal plate S is cooled by the refrigerant CF from the cooling tank 11 and the refrigerant CF sprayed from the multiple nozzles 12.

[0035] like Figure 1 As shown, by using both the cooling tank 11 and multiple ejection nozzles 12 to cool the metal plate S, the boiling state of the surface of the metal plate S can be stabilized, and uniform shape control can be achieved. It should be noted that... Figure 1The example shown is of a cooling device 10 comprising a cooling tank 11 and multiple spray nozzles 12, but for example, the metal plate S may be cooled using only the cooling tank 11 without using the spray nozzles 12. Furthermore, the cooling device 10 may cool the metal plate S by spraying, water jet cooling from the nozzles only, or gas cooling. Additionally, a water quenching method using water as the refrigerant CF is shown, but oil cooling using oil as the refrigerant CF is also possible. Moreover, the fluid stored in the cooling tank 11 and sprayed from the spray nozzles 12 can be any cooling fluid, such as refrigerant CF. Figure 1 The example shows a case where multiple ejection nozzles 12 are arranged in a cooling tank 11, but the cooling method is not limited to this as long as it is a method that can cool the metal plate S within the desired temperature range.

[0036] Here, if the metal plate S already has warping before quenching, there is a possibility that warping may remain after quenching, and furthermore, quenching the warped metal plate S may worsen the warping. Therefore, it is desirable to suppress the occurrence of warping in the metal plate S before quenching, and it is desirable to correct the warping of the metal plate S before quenching through quenching. Therefore, in Figure 1 In the quenching apparatus 1, the metal plate S before quenching is pressed in according to its shape, and the shape of the metal plate S is corrected. Here, the "shape" of the metal plate S includes the "warping direction" and the "warping amount". Moreover, the "warping direction" is synonymous with the "protruding warped shape" in the metal plate S.

[0037] There are no particular limitations on the method for determining the shape of the metal plate S before quenching, as long as it allows for the determination of the warp direction and amount of warp. The shape of the metal plate S before quenching can also be calculated using a physical model that incorporates the annealing conditions and transport conditions of the metal plate S up to the point of imminent quenching, based on the shape measured at any position along the path of the plate before quenching. Alternatively, the shape of the metal plate S before quenching can be predicted using a machine learning model. Or, the shape can be measured using a shape measuring device just before quenching.

[0038] Alternatively, the shape of the subsequent material before quenching can be estimated based on the "warping direction" and "warping amount" measured in the shape determination of the quenched metal plate S (the prior material). Specifically, if the measured warping amount of the quenched metal plate S (the prior material) is greater than the average value of past manufacturing results (warping amount after quenching), it can be determined that it is affected by warping that existed before quenching, and the warping amount and warping direction of the metal plate S (the subsequent material) before quenching can be estimated. Furthermore, the estimated subsequent material can be adjusted based on the pressing direction and pressing amount of the shape-correcting roller.

[0039] Here, if the warpage of the metal plate S before quenching can be quantitatively determined, as described later, the pressing amount of the back-side pressing roller 30a and the surface-side pressing roller 30b can be determined based on this warpage. It should be noted that if the warpage of the metal plate S before quenching cannot be quantitatively determined, the pressing amount of the back-side pressing roller 30a and the surface-side pressing roller 30b can be determined based on data from past manufacturing practices, including the pressing amount of the back-side pressing roller 30a and the surface-side pressing roller 30b, and the corresponding warpage (flatter shape) of the quenched metal plate S. Furthermore, the warpage direction of the metal plate S before quenching tends to reflect the shape of the original plate entering the continuous annealing furnace; if the warpage shape of the original plate can be detected beforehand, the pressing direction and pressing amount of the shape-correcting rollers can be adjusted based on this information.

[0040] The following describes an implementation method for determining the shape of a metal plate S using a shape measuring device. Figure 1 The quenching apparatus 1 includes: a shape measuring device 20, which has the function of measuring the shape of a metal plate before quenching; a shape straightening roller 30; and a pressing control device 40, which controls the pressing of the shape straightening roller 30 based on the shape of the metal plate S measured by the shape measuring device 20. The shape measuring device 20 includes, for example, a shape measuring roller; specifically, a product called the BFI shape roller from VOLLMER Corporation can be used. Multiple piezoelectric sensors are provided on the shape measuring device 20 along the width direction, and the shape of the metal plate S can be measured by passing the metal plate S through the shape measuring device 20. As for the shape of the metal plate S, the shape measuring device 20 measures the warp direction of the metal plate S before quenching, preferably measuring the warp direction and the amount of warp. Figure 1 The example shown is of a shape measuring device 20 including a shape measuring roller, but it is not limited to this. For example, known techniques such as camera measurement and laser measurement can also be used to measure the shape of the metal plate S before quenching.

[0041] Figure 2 and Figure 3This is a schematic diagram illustrating the pressing of a shape-correcting roller 30 into a metal sheet S. The shape-correcting roller 30 includes a back-side pressing roller 30a that presses the metal sheet S from the back side, and a surface-side pressing roller 30b that presses the metal sheet S from the surface side. The back-side pressing roller 30a and the surface-side pressing roller 30b are arranged in an alternating pattern along the through-plate direction. The back-side pressing roller 30a and the surface-side pressing roller 30b are made of materials with excellent thermal conductivity and strength capable of withstanding the load when the metal sheet S is clamped. Examples of materials for the back-side pressing roller 30a and the surface-side pressing roller 30b include SUS304, SUS310, or ceramics as specified in Japanese Industrial Standard JIS G4304 "Hot-rolled Stainless Steel Sheet and Strip".

[0042] Figure 1 In the pressing process, the distance L between the center axes of the back-side pressing roller 30a and the front-side pressing roller 30b is preferably set so that they do not contact each other during pressing. For example, the distance L between the center axes is preferably between 100 mm and 1000 mm. If the distance between the center axes is less than 100 mm, the metal plate S may get stuck due to pressing and thus not be able to pass through. On the other hand, if the distance L between the center axes is greater than 1000 mm, there will be no constraint force, resulting in residual warping after quenching.

[0043] The center position of the surface-side pressing roller 30b, which is positioned relatively close to the cooling device 10, is preferably within 500 mm of the cooling start point SP. This is because if the shape correction position in the metal plate S is too far from the cooling start point SP, which is the martensitic phase transformation temperature, the effect of suppressing out-of-plane deformation during cooling is reduced. Furthermore, considering interference with the cooling equipment, it is preferable to be at least 50 mm away from the cooling start point. Moreover, the diameters of the back-side pressing roller 30a and the surface-side pressing roller 30b are not particularly limited, but from the perspective of maintenance and operating costs, the diameters are preferably 100 mm to 500 mm. When predicting the shape of the metal plate S, it is also preferable to predict the shape of the metal plate S at a position as close as possible to the cooling start point SP.

[0044] like Figure 2 and Figure 3 As shown, the back-side pressing roller 30a and the front-side pressing roller 30b are configured to be movable in the thickness direction of the metal plate S. The pressing direction and pressing amount of the back-side pressing roller 30a and the front-side pressing roller 30b are controlled by the pressing control device 40. Furthermore, in order to prevent roller defects from occurring on the metal plate S, it is preferable to rotate the back-side pressing roller 30a and the front-side pressing roller 30b in the circumferential direction by means of electric power.

[0045] Figure 1The pressing control device 40 controls the pressing amount of the back-side pressing roller 30a and the front-side pressing roller 30b onto the metal plate S according to the warping direction of the metal plate S. The pressing control device 40 controls the pressing amount by pressing the metal plate S with the front-side pressing roller (back-side pressing roller 30a or front-side pressing roller 30b) that will form a convex, warped shape. For example, as... Figure 2 As shown, when the metal plate S has a warped shape that bulges outwards, the pressing control device 40 presses the surface pressing roller 30b into the metal plate S. On the other hand, as... Figure 3 As shown, when the metal plate S has a warped shape that bulges out to the back side, the pressing control device 40 presses the back side pressing roller 30a into the metal plate S.

[0046] Figure 4 This is a schematic diagram illustrating the definition of the warpage amount d. The pressing control device 40 preferably controls the pressing amount of the back-side pressing roller 30a and the front-side pressing roller 30b based on the warpage amount d. When the warpage amount d is measured in the shape measuring device 20, the pressing control device 40 sets the warpage amount d of the metal plate S as the pressing amount Pd and presses the shape correcting roller 30 in (d = Pd). The pressing amounts of the back-side pressing roller 30a and the front-side pressing roller 30b are set based on the case where the metal plate S is passed through in a straight line (0 mm). Therefore, the larger the warpage amount d of the metal plate S, the larger the pressing amount. It should be noted that if the warpage of the metal plate S is not detected or estimated, it is preferable to retract the shape correcting roller 30 to a position where it does not contact the metal plate S.

[0047] Reference Figure 1 The quenching method and steel plate manufacturing method of the present invention will be described. First, the shape of the metal plate S before quenching, including its warp direction and warp amount d, is determined. Then, according to the warp direction of the metal plate S, the shape straightening roller 30 is pressed into the thickness direction of the metal plate S. Specifically, when the metal plate S has a warped shape that bulges towards the surface, such as... Figure 2 As shown, the surface-side pressing roller 30b is pressed into the metal plate S. When the metal plate S has a warped shape bulging towards the back side, as... Figure 3 As shown, the back-side pressing roller 30a presses the metal plate S. At this time, the pressing amount Pd is set to be the same as the warpage amount d. Then, the metal plate S is cooled by the cooling device 10 and quenched.

[0048] According to the above embodiment, the shape of the metal plate S before quenching is determined, and the shape-correcting roller 30 is pressed into the thickness direction of the metal plate S according to the shape of the metal plate S. Therefore, when the metal plate S is continuously passed through and quenched, even if the metal plate before quenching has warping, the warping of the metal plate after quenching can be suppressed.

[0049] In conventional metal sheet quenching, if the metal sheet already has warping before quenching, quenching further amplifies this warping. Since the warping already exists before quenching, the bending moment acting on the metal sheet during quenching acts in a direction that exacerbates the warping due to resistance in the direction that would restore the warping. Therefore, the warping direction of the metal sheet before quenching is the same as that after quenching, and the amount of warping becomes greater than before quenching.

[0050] In conventional quenching processes, since pre-quenching warpage is not considered, it is ideal for the steel plate to cool uniformly on both the surface and back sides for the desired shape. However, if warpage is known beforehand, countermeasures can be taken to correct it. Therefore, by knowing the warpage, after correcting the warpage using the shape-correcting roller 30, quenching is performed using the cooling device 10. Thus, even if the metal plate S has warpage before quenching, the warpage that worsens during cooling can be suppressed, ultimately preventing warpage of the quenched metal plate.

[0051] In particular, this invention can reduce the complex and uneven uneven shape that occurs when the martensitic phase transformation occurs during the rapid cooling of the metal plate S, resulting in volume expansion of the microstructure. Therefore, when the metal plate S is a high-strength steel plate (high-tensile steel), the deformation suppression effect is greater. Specifically, the quenching apparatus 1 is preferably applied to the quenching of the metal plate S when it is a high-strength steel plate. More specifically, it is preferably applied to the manufacture of steel plates with a tensile strength of 580 MPa or higher. There is no particular upper limit to the tensile strength, but as an example, it can be 2000 MPa or lower. The aforementioned high-strength steel plates (high-tensile steel) include high-strength cold-rolled steel plates, and molten galvanized steel plates (molten galvanized treated steel plates), electro-galvanized steel plates (electro-galvanized treated steel plates), alloyed molten galvanized steel plates (alloyed molten galvanized treated steel plates), etc., to which surface treatment (plating treatment) has been performed. Specific examples of the composition of high-strength steel plates include, by mass percent, C of 0.04% to 0.35%, Si of 0.01% to 2.50%, Mn of 0.80% to 3.70%, P of 0.001% to 0.090%, S of 0.0001% to 0.0050%, sol.Al of 0.005% to 0.065%, at least one of Cr, Mo, Nb, V, Ni, Cu, and Ti each of 0.5% or less as needed, further, B and Sb each of 0.01% or less as needed, with the balance being Fe and unavoidable impurities. It should be noted that the embodiments of the present invention are not limited to examples of quenching steel plates, but can be applied to the quenching of entire metal plates other than steel plates.

[0052] Example

[0053] Embodiments of the present invention will be described. Examples 1 to 14 of the present invention will be used... Figure 1 The quenching apparatus 1 manufactures a high-tensile cold-rolled steel sheet with a tensile strength of 1470 MPa, having a thickness of 1.0 mm and a width of 1000 mm, as metal sheet S. Furthermore, the composition of the high-tensile cold-rolled steel sheet with a tensile strength of 1470 MPa, by mass%, is: C 0.20%, Si 1.0%, Mn 2.3%, P 0.005%, and S 0.002%. Water is used as the refrigerant CF, and the water temperature is 30°C.

[0054] On the other hand, as Comparative Examples 1 to 6, the high-tensile cold-rolled steel sheet described above was manufactured using the quenching apparatus shown in Patent Document 1, with other conditions identical to those in the present invention. In any of the apparatuses, the diameter of the shape-correcting rollers was 100 mm. Then, for Examples 1 to 12 of the present invention and Comparative Examples 1 to 6, the relationship between the warpage of the metal sheet S before quenching and the warpage of the metal sheet S after quenching was measured. For Examples 13 and 14 of the present invention, the "warpage direction" and "warpage amount" of the metal sheet S before quenching were estimated without measuring them. It should be noted that the definition of warpage amount d is shown in Figure 4 Regarding Examples 1-12 of the present invention and Comparative Examples 1-6, warpage is determined to be suppressed as long as the warpage amount of the quenched metal plate S is less than or equal to the warpage amount before quenching. Furthermore, regarding Examples 13 and 14 of the present invention, warpage is determined to be suppressed as long as the warpage amount of the quenched metal plate S (in the subsequent material) is less than or equal to the warpage amount of the quenched metal plate S (in the preceding material). The warpage amounts of Examples 1-14 of the present invention and Comparative Examples 1-6 are shown in Table 1 below.

[0055] [Table 1]

[0056]

[0057] Note 1: "*" indicates an estimated value.

[0058] Note 2: "Underlined number" indicates the warpage of the material after quenching. The value after that is the warpage amount after the material has been quenched.

[0059] As shown in Table 1, in Examples 1 to 12 of the present invention, even when warping already existed in the metal plate S before quenching, warping of the metal plate S after quenching could be suppressed. It should be noted that, as in Example 10 of the present invention, when the distance between the central axes is greater than 1000 mm, although the warping of the metal plate S before quenching is corrected, warping remains in the quenched steel plate compared to cases with a distance of less than 1000 mm. Furthermore, as in Example 6 of the present invention, when the distance between the shape-correcting roller 30 (surface pressing roller 30b) and the cooling start point SP is greater than 500 mm, although the warping of the metal plate S before quenching is corrected, warping remains in the quenched steel plate compared to cases with a distance of less than 500 mm. On the other hand, in Comparative Examples 1 to 6, when warping already existed in the steel plate S before quenching, the warping of the quenched metal plate S increased.

[0060] In Examples 13 and 14 of this invention, the warpage direction and amount of the metal plate S (the prior material) after quenching are visually confirmed using a camera image, thereby estimating the shape of the metal plate S (the subsequent material) before quenching. Specifically, the amount of warpage of the metal plate S (the prior material) after quenching is measured by the following method: using images taken from the edge side (both ends in the width direction) of the metal plate S, the location where the warpage amount is maximized is detected by image analysis and aligned with an actual scale. Then, it is compared with the average value of past manufacturing results (warpage amount after quenching), and if the measured warpage amount is large, it is determined that the shape of the metal plate S before quenching is warped. Furthermore, if it is determined that "warpage exists", the amount of warpage before quenching is estimated based on the discrepancy between the average value of past manufacturing results (warpage amount after quenching) and the measured warpage amount. Therefore, it is preferable to collect actual manufacturing results in advance and to understand in advance the correlation between the average value of the actual manufacturing results (warpage after quenching) and the deviation between the measured warpage and the warpage before quenching. In addition, for estimating the warpage direction of metal plate S (the subsequent material), it is estimated based on the warpage direction of metal plate S (the preceding material) since the warpage direction of metal plate S before and after quenching is the same.

[0061] Then, by adjusting the pressing direction and pressing amount of the shape-correcting rollers 30 on the surface and back of the metal plate S (the subsequent material) based on the estimated "warping direction" and "warping amount" before quenching, it was confirmed that the warping amount after quenching could be improved in the subsequent material under the same conditions. It should be noted that in the same coil under the same manufacturing conditions, since the warping amount before quenching does not change significantly in the length direction, it was confirmed that by determining the presence, direction, and amount of warping shape before quenching while confirming the warping amount after quenching, and adjusting the pressing direction and pressing amount of the shape-correcting rollers 30 on the surface or back of the metal plate S, the warping amount after quenching can be improved.

[0062] In this invention example, although the premise is to reduce the amount of warping after quenching, depending on the equipment of the through-plate path, if the allowable range of warping on one side (surface or back side) of the metal plate S is narrow, it is also possible to adjust the warping direction, such as changing the warping direction to the other side (back side or surface).

[0063] Explanation of reference numerals in the attached figures

[0064] 1 Quenching device

[0065] 2 Submerged Rollers

[0066] 10. Cooling device

[0067] 11 Cooling tank

[0068] 12. Spray nozzle

[0069] 20 Shape measuring device

[0070] 30 Shape Correcting Rollers

[0071] 30a Backside Press Roller

[0072] 30b Side Press Roller

[0073] 40 Press-in control device

[0074] CF refrigerant

[0075] L Interaxial distance

[0076] Pd injection amount

[0077] S metal plate

[0078] SP Cooling Start Point

[0079] d Warpage

Claims

1. A quenching apparatus for cooling a metal plate, the quenching apparatus comprising: A cooling device that uses cooling fluid to cool the metal plate for quenching; Shape-correcting rollers, respectively disposed on the surface and back sides of the metal plate, press the metal plate into the sheet before quenching in the thickness direction; and The pressing control device estimates the shape of the subsequent metal sheet before quenching based on the average value of the warp amount of the metal sheet after quenching, which is a past manufacturing result, and the shape of the metal sheet after quenching, which is a prior material, and sets the pressing amount of the shape-correcting roller based on the estimated shape of the metal sheet.

2. The quenching apparatus as described in claim 1, wherein, The pressing control device is controlled in the following manner: when the metal plate before quenching has a warped shape that bulges towards the surface, the shape straightening roller on the surface side of the metal plate is pressed in; when the metal plate before quenching has a warped shape that bulges towards the back side, the shape straightening roller on the back side of the metal plate is pressed in.

3. The quenching apparatus as described in claim 1 or 2, further comprising a shape measuring device for measuring the shape of the metal plate before quenching.

4. The quenching apparatus as described in claim 3, wherein, The shape measuring device has the function of measuring the warpage of the metal plate.

5. The quenching apparatus according to any one of claims 1 to 4, wherein, The distance between the center axes of the shape-correcting rollers on the surface side and the back side is set to be more than 100 mm and less than 1000 mm, and the distance between the cooling start point of the cooling device and the shape-correcting roller is within 500 mm.

6. A continuous annealing apparatus comprising a heat exchanger, wherein a quenching device according to any one of claims 1 to 5 is provided on the outlet side of the heat exchanger.

7. Quenching method, which is a quenching method that uses a cooling fluid to cool the metal plate for quenching, wherein, The shape of the subsequent metal plate before quenching is estimated by the average value of the warpage after quenching of the metal plate as a past manufacturing result and the shape of the metal plate after quenching, which is the prior material. Based on the estimated shape of the metal plate, the metal plate is pressed in the thickness direction using shape correction rollers respectively provided on the surface side and the back side of the metal plate.

8. The quenching method as described in claim 7, wherein, When pressing the metal plate in the thickness direction, if the metal plate before quenching has a warped shape that bulges towards the surface, the shape straightening roller on the surface side of the metal plate is pressed in; if the metal plate before quenching has a warped shape that bulges towards the back side, the shape straightening roller on the back side of the metal plate is pressed in.

9. The quenching method as described in claim 8, wherein, When determining the shape of the metal plate, it is necessary to determine the warping direction and the amount of warping. When pressing in the metal plate, the shape-correcting roller is pressed in with the amount of warpage of the metal plate as the pressing amount.

10. Methods for manufacturing steel plates, wherein, The steel plate, which is the metal plate, is quenched by the quenching method according to any one of claims 7 to 9.

11. A method for manufacturing galvanized steel sheets, wherein, The cold-rolled steel sheet manufactured by the steel sheet manufacturing method of claim 10 is subjected to a coating treatment.

12. The method for manufacturing galvanized steel sheet as described in claim 11, wherein, The plating treatment is any one of molten zinc plating, electroplating zinc plating, and alloyed molten zinc plating.

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