Steel sheet manufacturing method and steel sheet manufacturing device

Abstract

Provided is a steel sheet manufacturing method that can suppress the occurrence of rolling mill malfunctions caused by meandering. The present invention is a steel sheet manufacturing method that includes a rolling step in which a material to be rolled is rolled using a pair of work rollers disposed so as to mutually face one another. This steel sheet manufacturing method comprises: a leveling value acquisition step in which a leveling value corresponding to the distance between the work rollers is acquired; an information acquisition step in which form information on the material to be rolled and rolling information on the material to be rolled are acquired; a meandering quantity estimation step in which meandering quantities are estimated on the basis of the leveling value, the form information, and rolling conditions; and a leveling value setting step in which leveling values are set in accordance with the estimated meandering quantities. In the meandering quantity estimation step, a first meandering quantity and a second meandering quantity are estimated. In the leveling value setting step, a first leveling value is set that corresponds to the first meandering quantity and a second leveling value is set that corresponds to the second meandering quantity.

Description

Steel plate manufacturing method and steel plate manufacturing device

[0001] The present invention relates to a method and an apparatus for producing a steel plate by rolling a material to be rolled with work rolls.

[0002] A steel sheet is manufactured by rolling a material to be rolled in a rolling mill including a pair of rolls, for example. When the material to be rolled is rolled in the rolling mill, the material may be rolled in a state where the center position of the material in the width direction is misaligned with the center position of the roll, i.e., a state where so-called meandering occurs.

[0003] If a material being rolled is rolled while meandering, there is a risk that the steel plate will come into contact with the side guides installed on the rolling mill. There is also a risk that the tail end of the steel plate will be rolled in a bent state. These are factors that can cause problems requiring the replacement of rolling mill parts.

[0004] In hot rolling, a material to be rolled is heated in a heating furnace and then rough-rolled, followed by finish rolling. In finish rolling, a plurality of stands, each having a pair of rolls, are arranged, and the material to be rolled is rolled in each stand in turn, a process known as tandem rolling. In tandem rolling, meandering is likely to occur, and problems caused by meandering tend to occur.

[0005] One of the causes of meandering is the variation in the thickness of the steel sheet, i.e., thickness distribution. Conventionally, in order to suppress the occurrence of meandering, a method called leveling has been performed in which the left and right gap between the rolling rolls is adjusted to reduce the thickness distribution of the steel sheet. For example, Patent Document 1 discloses leveling using the difference in load between the left and right rolls and the difference in tension applied to the steel sheet in the width direction.

[0006] Furthermore, Patent Document 2 discloses adjusting the opening difference between the rolls so that the measured meandering amount of the steel sheet and the measured differential load of the rolls reach target values.

[0007] JP 2013-111592 A JP 2021-016888 A

[0008] However, the amount of bending at the tail end of a steel plate tends to be different from that at the steady state portion. Furthermore, it is not possible to measure tension at the tail end of a steel plate. Therefore, in Patent Document 1, even if the tail end side is adjusted using the value at the steady state portion, appropriate leveling cannot be performed, and there is still a risk of meandering occurring at the tail end of the steel plate. Furthermore, in Patent Document 1, leveling is performed when meandering has already occurred, which is problematic in that it is not possible to prevent the occurrence of meandering in advance.

[0009] In Patent Document 2, leveling is performed based on the amount of meandering of the steel sheet located before the rolling roll to be leveled and the differential load. Therefore, there is a high probability that the leveling will be performed after the steel sheet approaches the rolling roll to be leveled. Therefore, there is a risk that rolling will be performed with meandering still occurring at the leading edge of the steel sheet. Furthermore, Patent Document 2 has a problem in that leveling cannot be performed on a rolling mill located before the finish rolling.

[0010] The present invention has been made in consideration of the above problems, and aims to provide a method for manufacturing a steel sheet that can suppress the occurrence of rolling mill troubles caused by meandering.

[0011] In order to solve the above problems, the present invention has the following features.

[0012] [1] A method for manufacturing a steel plate, including a rolling step of rolling a material to be rolled with a pair of work rolls arranged opposite to each other, comprising: a leveling value acquisition step of acquiring a leveling value, which is the difference between the roll gap at one end side and the roll gap at the other end side in the axial direction of the pair of work rolls; an information acquisition step of acquiring shape information on the shape of the material to be rolled and rolling information on the rolling conditions of the material to be rolled; a meandering amount estimation step of estimating a meandering amount, which is the relative positional relationship between the center position in the width direction of the steel plate and the center positions in the width direction of the work rolls, based on the leveling value, the shape information and the rolling conditions; and a leveling value setting step of setting the leveling value according to the estimated meandering amount, wherein in the meandering amount estimation step, a first meandering amount which is the meandering amount of the front end of the steel plate and a second meandering amount which is the meandering amount of the tail end of the steel plate are estimated, a leveling value setting step of setting a first leveling value corresponding to the first meandering amount and a second leveling value corresponding to the second meandering amount, and a rolling step of rolling the steel plate at the first leveling value and the second leveling value set at the leveling value setting step according to a position of the steel plate. [2] A method for manufacturing a steel plate according to [1], wherein the leveling value setting step sets the second leveling value after a leading end of the rolled material has passed through the work rolls. [3] The method for manufacturing a steel plate according to [1] or [2], wherein in the rolling step, the rolled material is rolled sequentially in a rolling section in which a plurality of rolling stands each having a pair of work rolls are arranged in a conveying direction of the rolled material, and in the leveling value setting step, the leveling value is set for each of the rolling stands, and each leveling value is set so that the difference in thickness between both ends in the width direction of the rolled material in the rolling stand immediately preceding the rolling stand arranged at the most downstream position in the conveying direction is minimized.[4] A steel plate manufacturing apparatus having a pair of work rolls arranged opposite to each other and including a rolling unit that rolls a material to be rolled, the apparatus comprising: a leveling value acquisition unit that acquires a leveling value corresponding to the distance between the work rolls; an information acquisition unit that acquires shape information on the shape of the material to be rolled and rolling information on the rolling conditions of the material to be rolled; a meandering amount estimation unit that estimates a meandering amount that is the relative positional relationship between the center position in the width direction of the steel plate and the center positions in the width direction of the work rolls based on the leveling value, the shape information, and the rolling conditions; and a leveling value setting unit that sets the leveling value according to the estimated meandering amount, wherein the meandering amount estimation unit estimates a first meandering amount that is the meandering amount of the leading end of the steel plate and a second meandering amount that is the meandering amount of the tail end of the steel plate, and the leveling value setting unit sets a first leveling value corresponding to the first meandering amount and a second leveling value corresponding to the second meandering amount, A steel plate manufacturing apparatus, wherein the rolling unit rolls the steel plate using the first leveling value and the second leveling value set by the leveling value setting unit depending on the position of the steel plate. [5] The steel plate manufacturing apparatus according to [4], wherein the leveling value setting unit sets the second leveling value after the leading end of the rolled material has passed the work rolls. [6] The rolling unit has a plurality of rolling stands, each having the pair of work rolls, arranged in a conveying direction of the rolled material, and the leveling value setting unit sets the leveling value for each of the rolling stands, and sets each of the leveling values ​​so that a difference in thickness between both ends in the width direction of the rolled material in the rolling stand immediately preceding the rolling stand arranged furthest downstream in the conveying direction is minimized.

[0013] According to the steel sheet manufacturing method of the present invention, a first leveling value corresponding to a first meandering amount, which is the amount of meandering at the leading end of the steel sheet, and a second leveling value corresponding to a second meandering amount, which is the amount of meandering at the tail end of the steel sheet, are set, so that rolling can be performed with the amount of meandering suppressed. This makes it possible to suppress the occurrence of rolling mill troubles caused by meandering.

[0014] 1 is an explanatory diagram showing the configuration of a steel plate manufacturing apparatus; 2 is an explanatory diagram showing the configuration of a rolling stand; 3 is a functional block diagram of a rolling control section; 4 is a flow chart showing a subroutine of the leveling value setting step of FIG. 4; 5 is an explanatory diagram showing the concepts of camber amount and meandering amount; 6 is a graph showing the meandering amount of a comparative example in each rolling stand; 7 is a graph showing the meandering amount of an example in each rolling stand;

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a steel sheet manufacturing apparatus 100. In the steel sheet manufacturing apparatus 100 of FIG. 1, a slab SB as a material to be rolled is transported in a transport direction D1 to manufacture a steel sheet. Note that the material to be rolled is not limited to a slab SB, and for example, a billet, a bloom, or the like can also be used. In this embodiment, an example will be described in which a slab SB is used as the material to be rolled.

[0016] The steel plate manufacturing apparatus 100 has a heating furnace 10. In the heating furnace 10, the slab SB is heated to a predetermined temperature. The steel plate manufacturing apparatus 100 has a width reducing section 20. In the width reducing section 20, the slab SB is reduced in the width direction until it has a predetermined width.

[0017] The steel plate manufacturing apparatus 100 has a roughing rolling section 30 and a finish rolling section 40. The roughing rolling section 30 has a plurality of rolling stands 31, each having a pair of work rolls. In this embodiment, the rolling stands 31 are arranged along the conveyance direction D1. The number of rolling stands 31 is not particularly limited, but for example, five rolling stands 31 can be provided. The slab SB is rolled sequentially by the rolling stands 31 arranged along the conveyance direction D1.

[0018] The finishing rolling section 40 has a plurality of rolling stands 41, each having a pair of work rolls. In this embodiment, the rolling stands 41 are arranged along the conveying direction D1. The slab SB is rolled sequentially by the rolling stands 41 arranged along the conveying direction D1.

[0019] In the rough rolling section 30, the width-reduced slab SB is subjected to rough rolling until it reaches a predetermined thickness. In addition, in the finish rolling section 40, the rough-rolled slab SB is subjected to finish rolling until it reaches a predetermined thickness. The slab SB that has been finish-rolled in the finish rolling section 40 becomes a steel plate.

[0020] The steel plate manufacturing apparatus 100 has a run-out table 50 that cools the finish-rolled steel plate, and a coiler 60 that winds up the cooled steel plate. In the run-out table 50, the steel plate is cooled to a predetermined temperature by spraying cooling water. The finish rolling unit 40 is connected to a rolling control unit 70 that controls the rolling mode in the finish rolling unit 40.

[0021] Fig. 2 shows the configuration of the rolling stand 41. As shown in Fig. 2, the rolling stand 41 has a pair of work rolls 42a, 42b that are arranged to face each other.

[0022] The pair of work rolls 42a, 42b are supported by a pair of backup rolls 43a, 43b. The pair of work rolls 42a, 42b are spaced apart in the vertical direction.

[0023] The pair of backup rolls 43 a, 43 b support the pair of work rolls 42 a, 42 b from above and below, suppressing deflection of the work rolls 42 a, 42 b. The rolling stand 41 is not limited to the four-stage type shown in FIG. 2, but may be a six-stage type.

[0024] The rolling stand 41 is provided with a screw down device 44 that adjusts some of the rolling conditions. The screw down device 44 adjusts the spacing between the pair of work rolls 42a, 42b, i.e., the roll gap, so that the rolling load applied to the slab SB becomes a predetermined value. The screw down device 44 is provided so as to be able to adjust the roll gap between one end and the other end of the work rolls 42a, 42b in the axial direction. Hereinafter, the difference between the roll gap at one end of the pair of work rolls and the roll gap at the other end in the axial direction is also referred to as the leveling value.

[0025] Fig. 3 shows functional blocks of the rolling control unit 70. As shown in Fig. 3, the rolling control unit 70 has an input / output unit 71 connected to external devices, a storage unit 72 that stores various data, and a control unit 73 that controls the operation of the rolling control unit 70. The input / output unit 71, storage unit 72, and control unit 73 are connected to each other via a bus 74 so as to be able to communicate data with each other.

[0026] The input / output unit 71 is an interface that is provided to enable data communication with external devices. In this embodiment, the input / output unit 71 is connected to the finish rolling unit 40.

[0027] The storage unit 72 is a writable non-volatile memory such as an EPROM. The storage unit 72 is not particularly limited, but may be, for example, a storage device such as an HDD or SSD. The storage unit 72 stores morphology information related to the shape of the slab, rolling information related to the rolling conditions of the slab, and the like.

[0028] The morphology information includes dimensional values ​​including the thickness, length, and width of the slab, the thickness distribution in the width direction at the leading end (hereinafter also referred to as the wedge), the thickness distribution in the width direction at the tail end, deformation resistance, etc. Here, it is preferable to use values ​​before finish rolling as the morphology information. The wedge can be calculated, for example, as the difference between the thickness at one end in the width direction and the thickness at the other end, i.e., the difference in thickness at both ends in the width direction.

[0029] The rolling information includes the Young's modulus of the work rolls 42a, 42b, the crown of the work rolls 42a, 42b, the rolling speed of the rolling stand 41, the coefficient of friction, the tension between the rolling stands 41, the diameter of the work rolls 42a, 42b, the barrel length, the distance between the screws, the rigidity of the mill, the rigidity of the housing, the current leveling value setting, etc. The leveling value corresponds to the distance between the work rolls 42a, 42b.

[0030] The control unit 73 is a computer including a CPU. The control unit 73 controls the operation of the rolling control unit 70. The control unit 73 has a leveling value acquisition unit 75 that acquires a leveling value, an information acquisition unit 76 that acquires configuration information and rolling information, a meandering amount estimation unit 77 that estimates the meandering amount, and a leveling value setting unit 78 that sets the leveling value. The meandering amount is the relative positional relationship between the center position in the width direction of the steel plate and the center position in the width direction of the work roll.

[0031] The functions of the leveling value acquisition unit 75 , the information acquisition unit 76 , the meandering amount estimation unit 77 , and the leveling value setting unit 78 are realized by executing the programs stored in the storage unit 72 .

[0032] The leveling value acquisition unit 75 reads out the rolling information stored in the memory unit 72 and acquires the leveling values ​​of each rolling stand 41 in the finishing rolling unit 40 .

[0033] The information acquisition unit 76 reads out the morphological information stored in the storage unit 72 and acquires the morphological information.

[0034] The meandering amount estimation unit 77 estimates the meandering amount, which is the relative positional relationship between the center position of the steel plate in the width direction and the center position of the work roll in the width direction. The meandering amount estimated by the meandering amount estimation unit 77 is stored in the memory unit 72.

[0035] The leveling value setting unit 78 sets a leveling value in accordance with the meandering amount estimated by the meandering amount estimating unit 77. The leveling value set by the leveling value setting unit 78 is stored in the storage unit 72.

[0036] 4 shows a flow of the method for manufacturing a steel sheet. As shown in Fig. 4, the leveling value acquisition unit 75 reads out the leveling values ​​of each rolling stand 41 from the storage unit 72 and executes a leveling value acquisition step (step S101).

[0037] The information acquisition unit 76 reads out the shape information and rolling information stored in the storage unit 72 and executes an information acquisition step (step S102).

[0038] The meandering amount estimation unit 77 executes a meandering amount estimation step of estimating the meandering amount based on the leveling value, the configuration information, and the rolling conditions (step S103). In the meandering amount estimation step of step S103, the meandering amount estimation unit 77 estimates the meandering amount by using, for example, a nonlinear physical model. In the meandering amount estimation step of step S103, a first meandering amount which is the meandering amount of the leading end portion of the steel sheet and a second meandering amount which is the meandering amount of the tail end portion of the steel sheet are estimated.

[0039] The leveling value setting unit 78 sets a leveling value in accordance with the meandering amount estimated by the meandering amount estimating unit 77, and executes a leveling value setting step (step S104).

[0040] In the leveling value setting process of step S104, the leveling value setting unit 78 sets the leveling value so that the thickness distribution in the width direction, that is, the wedge, is minimized, for example.

[0041] Next, the slab is rolled using the leveling value set in the leveling value setting step of step S104, and the rolling step is carried out (step S105).

[0042] 5 shows a subroutine of the leveling value setting step of step S104. As shown in Fig. 5, the leveling value setting unit 78 determines whether the meandering amount estimated in the meandering amount estimation step of step S103 is equal to or greater than a threshold value (step S201).

[0043] If it is determined in step S201 that the amount of meandering is equal to or greater than the threshold, the leveling value setting unit 78 calculates a leveling value that provides an appropriate amount of meandering, and executes a leveling value calculation step (step S202).

[0044] In the leveling value calculation process of step S202, the leveling value setting unit 78 calculates a leveling value such that (1) the wedge of the slab is minimized and (2) the camber amount of the slab in each rolling stand 41 is acceptable.

[0045] Figure 6 shows the concepts of camber amount and meandering amount. In Figure 6, the direction from the leading edge of the slab SB to the trailing edge is shown as the x-direction, and the height direction of the slab SB is shown as the y-direction. The camber amount is the amount of lateral bending of the slab SB. In the figure, the camber amount is the relative displacement Δy from the steady-state position, which is represented by the midpoint of the slab SB in the x-direction, to the corresponding position in the y-direction at the leading edge or the trailing edge of the slab SB.

[0046] The camber amount is uniquely determined using the position of the leading or trailing end of the slab SB as a reference point. The reference point can be, for example, the very front or very rear end. The camber amount does not depend on the position in the x direction.

[0047] The meandering amount is the absolute displacement from the mill center position in the x direction in the figure. The meandering amount is expressed as ξ(x) with the position in the x direction as a variable. In other words, the meandering amount is a parameter that changes with time series for the slab SB moving in the x direction with the rolling speed.

[0048] The camber amount of the slab can be obtained, for example, by performing image processing on an image of the slab. The image used to determine the camber amount is preferably taken from the leading end to the trailing end of the slab. When determining the camber amount, shape data relating to the bending of the steel plate is obtained by performing image processing on the image.

[0049] Specifically, the edge of the steel plate is extracted by binarizing the image and detected. The amount of bending is then calculated based on the distance between the coordinate of the edge and a reference position. When calculating the amount of bending, data that serves as a reference for length in the image is used.

[0050] When determining the camber amount, it is preferable to use an image of the slab after rough rolling by the roughing mill 30 and before finish rolling by the finish rolling mill 40.

[0051] The leveling value setting unit 78 generates and executes a mathematical optimization model that minimizes the objective function, with the slab wedge as the objective function and the amount of meandering being within a predetermined target range as a constraint, to calculate the leveling value.

[0052] The wedge may be a wedge on the delivery side of the finishing rolling section 40 or a wedge change ratio. The target range of the meandering amount may be, for example, the excess width range of the side guide. Furthermore, the mathematical optimization model may be either quadratic programming or linear programming.

[0053] The leveling value setting unit 78 derives the change in the amount of outlet meandering (Δξ / ΔLev) by nonlinear physical model numerical analysis when the leveling value of each rolling stand 41 is slightly changed (ΔLev).

[0054] Next, the leveling value setting unit 78 derives linear approximation equations for the meandering amount and wedge on the delivery side that satisfy the following equations (1) and (2). In equation (1), ε is the meandering amount, A is the intercept when linear approximation is performed, and in equation (2), hd is the wedge, and B is the intercept when linear approximation is performed.

[0055]

[0056]

[0057] The leveling value setting unit 78 calculates hd(Lev) in the formula (2). ２ The leveling value (Lev') is calculated by quadratic programming so that the leveling value (Lev') is minimized and the amount of meandering on the exit side satisfies the target range as a constraint. The target range of the amount of meandering can be, for example, -20 mm≦ξ(Lev)≦20 mm.

[0058] The leveling value setting unit 78 determines a leveling value for each of the leading end and the trailing end of the slab. That is, the leveling value setting unit 78 determines a first leveling value corresponding to a first meandering amount and a second leveling value corresponding to a second meandering amount.

[0059] Here, when a constant leveling value is set from the leading edge to the trailing edge as in the conventional method, there is a risk that the camber amount at the trailing edge will increase if the leading edge and trailing edge camber amounts or their positive and negative values ​​(camber directions) are different. In this way, by determining a first leveling value corresponding to the first meandering amount and a second leveling value corresponding to the second meandering amount, that is, by determining leveling values ​​for each of the leading edge and the trailing edge, it is possible to reduce the meandering amount of the entire steel sheet.

[0060] The leveling value setting unit 78 sets the leveling value of the finish rolling unit 40 using the leveling value calculated in the leveling value calculation step of step S202, and executes the setting step (step S203).

[0061] In the leveling value setting step of step S203, the leveling value setting unit 78 sets a first leveling value corresponding to the first meandering amount, and sets a second leveling value corresponding to the second meandering amount.

[0062] The leveling value setting unit 78 sets the second leveling value, for example, after the leading edge of the slab has passed the work rolls. The leading edge of the slab can be set arbitrarily, for example, by dividing the slab into three parts in the longitudinal direction. Alternatively, the leading edge of the slab may be divided into two parts in the longitudinal direction, and one of these parts may be set as the leading edge.

[0063] In addition, the change from the first leveling value to the second leveling value can be made at any timing, and may be made after a predetermined time has elapsed after the slab reaches the rolling stand 41 located upstream in the conveying direction D1.

[0064] The leveling value setting unit 78 sets a leveling value for each rolling stand, and sets each leveling value so that the difference in thickness between both ends of the slab in the width direction at the rolling stand immediately preceding the rolling stand located at the most downstream position in the conveying direction D1 is minimized.

[0065] In this way, the meandering amount can be adjusted appropriately in each rolling stand, and the meandering amount in the final stand can be adjusted with high precision.

[0066] The leveling value setting unit 78 determines whether the leveling value (Lev') calculated in this manner is equal to or greater than a threshold value (step S204). If the leveling value is equal to or greater than the threshold value in the determination in step S204 (step S204: YES), the leveling value setting unit 78 repeats the leveling value calculation process in step S202 and the setting process in step S203 described above until the amount of meandering becomes less than the threshold value. That is, the leveling value setting unit 78 uses nonlinear physical model numerical analysis and a mathematical optimization method to find the optimal value of the leveling value.

[0067] The leveling value setting unit 78 ends the process when the amount of meandering is determined to be less than the threshold value in step S201 or step S204.

[0068] 4, the leveling value acquisition step in step S101 to the rolling step in step S105 may be repeated. For example, in the leveling value acquisition step in step S101, it is preferable to acquire the set value from the leveling value setting step in step S104 that was performed immediately before. In this way, the leveling values ​​can be set continuously, making it possible to more effectively suppress the occurrence of rolling mill troubles caused by meandering.

[0069] That is, by performing the above-mentioned process integrally for the entire length of the slab SB until the end of rolling, it becomes possible to calculate the meandering amount ξ, leveling value, and wedge for the entire length of the slab SB. Specifically, the meandering amount ξ can be calculated using the following equation.

[0070]

[0071] In the formula (3), t is the timing at which the previous leveling value was set, and Δt is the timing at which the leveling value is set.

[0072] Therefore, when a new leveling value is set, the leveling value is set with reference to the previously set leveling value, so that the amount of meandering can be obtained over the entire length of the slab SB.

[0073] The new leveling value can be set, for example, according to the position of the slab SB and the time elapsed since the previous leveling value was set. When the new leveling value is set according to the position of the slab SB, for example, the new leveling value can be set when the slab SB arrives at each rolling stand.

[0074] Furthermore, when the leveling value is set according to the time that has elapsed since the previous leveling value was set, for example, a new leveling value can be set when 0.01 seconds has elapsed since the previous leveling value was set.

[0075] The leveling value acquired in the leveling value acquisition process of step S101 is not limited to the leveling value set immediately before, but can be a leveling value set at any position and any time. In this way, it is possible to calculate the meandering amount, leveling value, meandering amount, and wedge at any position and any time in the full length direction of the slab SB.

[0076] In the above embodiment, an example in which the present invention is applied to a finish rolling section has been described, but the present invention is not limited to this and can also be applied to other rolling processes, for example, a rough rolling section.

[0077] The leveling values ​​of the rolling stands were changed to produce steel sheets, and the amount of meandering in each rolling stand was confirmed. Note that, in each rolling stand, the first leveling value and the second leveling value were set as described above, and rolling was carried out to produce steel sheets, which were used as examples.

[0078] In addition, a comparative example was prepared in which the leveling values ​​in each rolling stand were set so as to minimize the wedge, and rolling was carried out to produce a steel sheet. For the comparative example, the leveling value of the front end was set, and the leveling value of the tail end was set to the same value as the leveling value of the front end.

[0079] The steel sheets were produced with the upper and lower limits of the leveling value set to ±0.5 mm and the excess width of the side guide, i.e., the target meandering amount, set to 20 mm. Figure 7 shows the meandering amount for each rolling stand in the comparative example. Figure 8 shows the meandering amount for each rolling stand in the example. In Figures 7 and 8, F1 to F5 indicate positions in the conveying direction of the slab. That is, F1 is the rolling stand located most upstream in the conveying direction, and F5 is the rolling stand located most downstream in the conveying direction.

[0080] As shown in Fig. 7, in the comparative example, a meandering amount exceeding the target meandering amount was detected in almost all rolling stands. In addition, in the comparative example, since the leveling values ​​of the head end and tail end were set to be the same, a tendency for greater meandering to occur at the tail end than at the head end was also observed.

[0081] As shown in Fig. 8, in the example, the meandering amount was detected within the target meandering amount from stand F2 onwards. Therefore, by performing rolling by setting the above-mentioned first leveling value and second leveling value, it was possible to suppress the meandering amount at the head end and tail end.

[0082] 100 Steel plate manufacturing device 75 Leveling value acquisition unit 76 Information acquisition unit 77 Meandering amount estimation unit 78 Leveling value setting unit

Claims

1. A method for manufacturing a steel plate, including a rolling step of rolling a material to be rolled with a pair of work rolls arranged opposite to each other, comprising: a leveling value acquisition step of acquiring a leveling value, which is the difference between the roll gap at one end side and the roll gap at the other end side in the axial direction of the pair of work rolls; an information acquisition step of acquiring shape information on the shape of the material to be rolled and rolling information on the rolling conditions of the material to be rolled; a meandering amount estimation step of estimating a meandering amount, which is the relative positional relationship between the center position in the width direction of the steel plate and the center positions in the width direction of the work rolls, based on the leveling value, the shape information and the rolling conditions; and a leveling value setting step of setting the leveling value in accordance with the estimated meandering amount, wherein in the meandering amount estimation step, a first meandering amount, which is the meandering amount of the front end of the steel plate, and a second meandering amount, which is the meandering amount of the tail end of the steel plate, are estimated, a first leveling value corresponding to the first meandering amount and a second leveling value corresponding to the second meandering amount are set in the leveling value setting step, and a second leveling value corresponding to the second meandering amount are set in the rolling step, depending on the position of the steel plate, 2. A method for manufacturing a steel plate according to claim 1, wherein in the leveling value setting step, the second leveling value is set after the leading end of the rolled material has passed through the work rolls.

3. A method for manufacturing steel plate as described in claim 1 or 2, wherein in the rolling process, the rolled material is rolled sequentially in a rolling section in which a plurality of rolling stands each having a pair of work rolls are arranged in the conveying direction of the rolled material, and in the leveling value setting process, the leveling value is set for each of the rolling stands, and each leveling value is set so that the difference in thickness between both ends of the rolled material in the width direction in the rolling stand immediately preceding the rolling stand arranged furthest downstream in the conveying direction is minimized.

4. A steel plate manufacturing apparatus having a pair of work rolls arranged opposite to each other and including a rolling section for rolling a material to be rolled, comprising: a leveling value acquisition unit that acquires a leveling value corresponding to the distance between the work rolls; an information acquisition unit that acquires shape information relating to the shape of the material to be rolled and rolling information relating to the rolling conditions of the material to be rolled; a meandering amount estimation unit that estimates a meandering amount, which is the relative positional relationship between the center position in the width direction of the steel plate and the center positions in the width direction of the work rolls, based on the leveling value, the shape information and the rolling conditions; and a leveling value setting unit that sets the leveling value in accordance with the estimated meandering amount, wherein the meandering amount estimation unit estimates a first meandering amount which is the meandering amount of the leading end of the steel plate and a second meandering amount which is the meandering amount of the tail end of the steel plate, and the leveling value setting unit sets a first leveling value corresponding to the first meandering amount and a second leveling value corresponding to the second meandering amount, In the rolling section, rolling is performed using the first leveling value and the second leveling value set by the leveling value setting section depending on the position of the steel plate.

5. A steel plate manufacturing apparatus as set forth in claim 4, wherein the leveling value setting unit sets the second leveling value after the leading end of the rolled material has passed through the work rolls.

6. A steel plate manufacturing device as described in claim 4 or 5, wherein the rolling section has a plurality of rolling stands, each having a pair of work rolls, arranged in the conveying direction of the rolled material, and the leveling value setting section sets the leveling value for each of the rolling stands, and sets each of the leveling values ​​so that the difference in thickness between both ends in the width direction of the rolled material in the rolling stand immediately preceding the rolling stand arranged furthest downstream in the conveying direction is minimized.

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