JP3664151B2 - Sheet width control method, cold rolled metal sheet manufacturing method, and cold rolling apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention performs control related to the plate width of the rolled plate, and in particular, a plate that suppresses fluctuations in the plate width of the rolled plate by performing the required control according to the rolling speed. The present invention relates to a width control method, a cold-rolled metal plate manufacturing method, and a cold rolling apparatus.
[0002]
[Prior art]
Recently, various control methods related to plate thickness accuracy and flat shape have been applied to cold rolling in order to cope with improvements in quality accuracy, productivity and yield required for steel plates. In particular, the control for the change in the plate width is particularly important because it is closely related to the yield. It has been found that the change in the sheet width due to rolling is affected by the change in rolling conditions. For example, when continuously rolling while welding the coil, the coil front and rear ends are rolled at a low speed, and the coil plate Since the intermediate portion in the length direction is rolled at a high speed to improve productivity, the rolling conditions change at a low speed and at a high speed, and a fluctuation in the plate width occurs in the plate length direction after rolling.
[0003]
Regarding the sheet width control method for cold rolling, JP-A-10-296312 discloses a control method for adjusting the sheet width to a target value by controlling the bending shape of the work roll of each stand of the tandem rolling mill. Yes. This control method is based on the premise that there is a proportional relationship between the change in sheet crown ratio and the change in sheet width before and after rolling, and the change in sheet crown ratio is kept constant with respect to fluctuations in rolling load accompanying changes in rolling speed. The amount of bending of the work roll to be maintained is calculated, and the work roll is adjusted to match the calculated amount of bending.
[0004]
In this way, by adjusting the work roll, the sheet width changed from T1 to T2 before and after the change point X of the rolling speed in the rolled steel sheet W (rolled sheet) shown in FIG. As in the steel plate W after rolling shown in FIG. 8 (b), the plate width is maintained at T1 even before and after the change point X of the rolling speed, and the fluctuation of the plate width in the plate length direction is suppressed. Yes. In addition, as shown in FIGS. 9 (a) and 9 (b), the change in the plate width in the proportional relationship which is a precondition for control is the plate width T10 of the steel plate W before rolling before and after rolling by a rolling mill, and after rolling. This means a difference from the plate width T11 of the steel plate W.
[0005]
The change in the plate crown ratio (hereinafter referred to as the plate crown ratio change) is the difference between the plate center amount and the plate crown amount in the width direction of the rolled plate. In the sheet crown ratio indicating the sheet thickness ratio, it means the difference between before and after rolling. Specifically, the plate crown before rolling amount Cri, the thickness of the plate center in the width direction of the rolled plate before rolling is H, the plate crown after rolling amount Is the plate thickness ratio Δγ, and the plate thickness at the central portion in the width direction of the rolled plate after rolling is h, the plate crown ratio change Δγ can be obtained by the following equation.
Δγ = Cro / h−Cri / H (1)
[0006]
[Problems to be solved by the invention]
As a result of continuing diligent research on sheet width control related to cold rolling, the present applicant has found it difficult to suppress fluctuations in sheet width in the sheet length direction when the rolling speed is changed in the conventional control method described above. I found out that there was a case. That is, even if the rolling speed changes, the change in the plate crown ratio and the change in the plate width maintain the proportional relationship, but the applicant has clarified that the slope of the straight line indicating the proportional relationship changes, and the plate crown for each straight line changes. Depending on the numerical value of the ratio change, we faced the problem that when the rolling speed was changed, it was not possible to cope with the suppression of sheet width fluctuation.
[0007]
As shown in FIG. 10, a straight line L10 indicates a proportional relationship between a change in the plate crown ratio and a change in the plate width when the rolling speed is V10. A straight line L11 having a slope different from that of the straight line L10 is obtained when the rolling speed is V11. The proportional relationship is shown. In the straight line L10, the plate width change when the plate crown ratio change is Δγ10 is ΔW10, but in the straight line L11, the plate width change when the plate crown ratio change is Δγ10 is ΔW11. Therefore, when the rolling speed is changed from V10 to V11, if the control of maintaining the plate crown ratio change to Δγ10 is performed by the conventional control method, the plate width change changes from ΔW10 to ΔW11 to the shrinking side, and the rolling speed is changed. There is a problem that the change in the plate width cannot be made constant before and after the change, and the plate width after rolling in the plate length direction varies.
[0008]
Depending on the rolling conditions, fluctuations in the sheet width may be suppressed by performing control to keep the sheet crown ratio change constant when the rolling speed changes. For example, at the point where the straight line L10 and the straight line L11 intersect, if the rolling speed is changed from V10 to V11, even if control is performed to maintain the plate crown ratio change to Δγ11, the plate width change is maintained at ΔW12. There is no change in the sheet width after rolling in the length direction.
[0009]
As described above, in the conventional control method, the case where the sheet width change cannot be made constant depending on the rolling conditions occurs, the friction coefficient change in the lubrication state between the work roll and the rolled sheet with the change in the rolling speed, and Only two points in total, the rolling load change accompanying the change in deformation resistance, which is the hardness change due to the strain rate change of the material to be rolled, are considered, and based on these changes, control is performed in a direction that suppresses the change in the plate crown ratio. It is mentioned.
[0010]
However, in reality, the metal flow also changes in the width direction due to the change in the friction coefficient, which needs to be taken into consideration. Furthermore, the conventional control method uses the plate crown amount, which is the difference in plate thickness between the plate center and the plate end, as an index indicating the change in the plate thickness distribution in the width direction, but the plate crown amount does not change. Even in this case, the plate thickness distribution in the width direction may change and the plate width may change. In such a case, it is considered that the conventional control method cannot cope with this.
[0011]
The phenomenon that the state of the proportional relationship between the change in the sheet crown ratio and the change in the sheet width due to the change in the rolling speed is listed as the following two factors of the rolling phenomenon.
[0012]
The first point is that the lubrication state between the work roll and the plate to be rolled changes according to the rolling speed, and the friction coefficient increases as the rolling speed becomes lower, thereby increasing the frictional stress in the width direction. The plate width is less likely to change.
[0013]
The second point is as follows. That is, in the low-speed rolling, the rolling load increases with an increase in the friction coefficient as compared with the high-speed rolling, while the deformation resistance decreases, the rolling load decreases and two contradictory phenomena occur at the same time. The influence of the increase in the friction coefficient is larger, and the rolling load increases as the rolling speed becomes lower as shown in FIG. When the thickness distribution in the width direction is examined according to the rolling speed that changes the rolling load in this way, even if the plate crown ratio change is kept constant at the plate crown evaluation position in the vicinity of the plate end in the width direction, the speed is low. During rolling, the plate thickness at the central portion side from the plate crown evaluation position is thicker than at high speed rolling, and the plate thickness is relatively thin at the end portion side.
[0014]
As shown in FIG. 12, the details are surrounded by the plate shape during low-speed rolling (shown by a broken line in the figure) and the plate shape during high-speed rolling (shown by a solid line in the figure) from the plate crown evaluation position to the center side. The relationship between the area S1 and the area S2 surrounded by the plate shape at each speed on the end side from the plate crown evaluation position is S1 <S2, and the end of the plate shape during the low speed rolling is the plate during the high speed rolling. Projecting from the end, the plate width increases, which is the second factor.
[0015]
The present invention has been made in view of such circumstances, and changes in sheet width after rolling in response to changes in metal flow in the width direction and changes in thickness distribution over the entire width due to changes in rolling speed. An object of the present invention is to provide a sheet width control method, a cold-rolled metal sheet manufacturing method, and a cold rolling apparatus that can suppress the above.
[0016]
[Means for Solving the Problems]
The sheet width control method according to the first invention relates to the roll gap of the stand in relation to the sheet crown ratio of the rolled sheet. distribution In the sheet width control method for controlling the sheet width of the sheet to be rolled by adjusting the step of storing the relationship between the sheet width change before and after rolling of the sheet to be rolled and the sheet crown ratio change according to the rolling speed; Based on the stored relationship, a step of calculating a plate crown ratio change that makes the plate width change the same according to the rolling speed, and the roll gap based on the calculated plate crown ratio change distribution Adjusting the step.
[0017]
The cold rolled metal sheet manufacturing method according to the second aspect of the present invention relates to the roll gap in relation to the sheet crown ratio of the rolled sheet. distribution Adjust section In the cold rolled metal sheet manufacturing method for cold-rolling the rolled sheet with the stand, the step of storing the relationship between the sheet width change before and after rolling of the rolled sheet and the change in sheet crown ratio according to the rolling speed, and Based on the stored relationship, a step of calculating a plate crown ratio change that makes the plate width change the same according to the rolling speed, and the roll gap based on the calculated plate crown ratio change distribution Adjusting the step.
[0018]
The cold rolling apparatus according to the third aspect of the present invention relates to the roll gap of the stand in relation to the plate crown ratio of the rolled sheet. distribution In the cold rolling apparatus for controlling the sheet width to cold-roll the rolled sheet, the relationship between the sheet width change before and after the rolling of the rolled sheet and the change in the sheet crown ratio depends on the rolling speed. Based on the relationship stored in the storage means, a storage means for storing, a calculation means for calculating a plate crown ratio change that makes the change in the plate width the same in accordance with the rolling speed, and a plate crown ratio calculated by the calculation means Roll gap based on change distribution And means for adjusting.
[0019]
In the cold rolling apparatus according to the fourth invention, the relationship is
ΔW = a (V) · Δγ + b (V) (2)
(However, ΔW is a change in sheet width, V is a rolling speed, a (V) is a first function corresponding to the rolling speed, Δγ is a change in sheet crown ratio, and b (V) is a second function corresponding to the rolling speed.)
It is characterized by being.
[0020]
In the cold rolling apparatus according to the fifth invention, the first function a (V) is
a (V) = c · (V−V0) ² + D (when V <V0) (3)
a (V) = d (when V ≧ V0) (4)
And
The second function b (V) is
b (V) = e · (V−V0) ² + F (when V <V0) (5)
b (V) = f (when V ≧ V0) (6)
(However, V0 is the boundary rolling speed with respect to the relationship between the plate width change and the plate crown ratio change, and c, d, e, and f are coefficients corresponding to the type and rolling dimensions of the plate to be rolled).
It is characterized by being.
[0021]
In the first invention, the second invention, and the third invention, by controlling based on the premise that the proportional relationship with the change in the plate width relative to the change in the plate crown ratio varies according to the rolling speed, the change in the plate width Can be maintained within a certain range. Specifically, various values of the plate crown ratio change that keeps the plate width change constant according to various rolling speeds are calculated, and the roll gap of the work roll is adjusted to correspond to the calculated plate crown ratio change. distribution The sheet width change can be made constant by adjusting, and as a result, the fluctuation of the sheet width in the sheet length direction after rolling can be suppressed.
[0022]
In other words, the amount of plate crown that is the basis for the change in the plate crown ratio is affected by the roll gap distribution of the work rolls, so the roll gap distribution By adjusting to a value corresponding to the change in the plate crown ratio according to the rolling speed, the change in the plate width can be suppressed. The roll gap of work rolls distribution There are various control methods for adjusting the angle, for example, it can be dealt with by controlling the correction amount of the bending force of the work roll.
[0023]
In addition, when the rolled plate is rolled by sequentially passing through a plurality of stands, the roll gap of the work roll of each stand distribution By adjusting as described above, fluctuations in the plate width can be suppressed, but the roll gap distribution The adjustment is not necessarily the same for all stands. For example, in the stand located on the upstream side and the stand located on the downstream side in the passing order of the rolled plate according to the type of rolled plate, the dimension to be rolled, the rolling conditions, etc., the roll gap distribution It is also possible to give a weight to the adjustment and provide a difference at each stand.
[0024]
Furthermore, it is not necessary to perform control according to the present invention for all of the plurality of stands. For example, the final stand on the downstream side is different from the control method according to the present invention in order to maintain the rolled product shape well. A method for controlling the shape of the work roll bending to be performed may be applied.
[0025]
In the fourth invention, in order to suppress the fluctuation of the sheet width by making the sheet width change constant before and after the change of the rolling speed, the sheet crown ratio change and the sheet width change are performed based on the above-described formula (2). By defining, it is possible to reliably calculate the plate crown ratio change that makes the plate width change constant according to the rolling speed. In addition, the roll gap of the work roll is set so that it matches the calculated crown crown ratio change. distribution By adjusting, the change in plate width can be made constant, and fluctuations in the plate width can be suppressed.
[0026]
In order to calculate the change in the sheet crown ratio after the change in the rolling speed based on the formula (2), first, an expression is provided in which the numerical value of the speed before the change in the rolling speed is substituted into the formula (2), and the rolling is performed. An equation in which the numerical value of the velocity after the change in velocity is substituted into equation (2) is provided, and the plate width variation is the same condition in these two equations, so that the simultaneous equations can be established.
[0027]
In addition, the plate crown ratio change Δγ and the roll gap of the work roll distribution It is known that the relationship with the control amount ΔF related to the adjustment is based on the following mathematical formula.
ΔF = (Δγ−k · ΔP) / g (7)
However, ΔP is a change in rolling load before and after the change in rolling speed, and g and k are determined by the actual rolling mill test results or FEM analysis results for each rolling condition such as the type of rolled sheet and rolling dimensions, respectively. This is the required coefficient.
[0028]
Therefore, the control amount ΔF can be obtained by substituting the numerical value of the plate crown ratio change obtained by the simultaneous equations according to the equation (2) into the equation (7), and the work roll of the work roll can be obtained based on the obtained control amount ΔF. Roll gap distribution By adjusting, the change in sheet width can be made constant even when the rolling speed changes variously.
[0029]
In addition, when rolling in order with each stand by a tandem rolling device having a plurality of stands, the roll gap of the i-th stand from the upstream side distribution The plate crown ratio before and after rolling by the whole tandem rolling apparatus is obtained in advance by obtaining the plate crown ratio change Δγi before and after rolling at the i-th stand with respect to the control amount ΔFi related to the adjustment of The change Δγ can be calculated by the following formula.
Δγ = Σ (Δγi) (8)
[0030]
Therefore, the following mathematical formulas can be derived from the mathematical formulas (7) and (8).
Σ (gi · ΔFi) = Δγ−Σ (ki · ΔPi) (9)
By substituting for this formula (9) the change in the sheet crown ratio after the change in the rolling speed and the change in the rolling load that accompanies the change in the rolling speed determined by the simultaneous equations described above, the roll gap in each stand distribution The control amount ΔFi related to can be calculated. Gi and ki are coefficients of the i-th stand from the upstream side.
[0031]
In addition, since there are a plurality of combinations of ΔFi, there is provided a constraint condition that the value weighted to gi · ΔFi at each stand is uniform, or a constraint condition that the value weighted to Δγi at each stand is uniform. ΔFi can be obtained.
[0032]
In the fifth invention, the numerical formulas (3) to (6) are substituted for the mathematical formula (2) in accordance with the rolling conditions such as the type of the rolled sheet and the rolling dimensions, so that the rolling conditions are met. Changes in the plate crown ratio can be obtained.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1: has shown the whole block diagram of the tandem rolling apparatus 10 which is a cold rolling apparatus which concerns on embodiment of this invention. The tandem rolling device 10 has a total of five stands 11 to 15 arranged in tandem at intervals. Each stand 11-15 is provided with a pair of work rolls 11c, 11d-15c, 15d between a pair of backup rolls 11a, 11b-15a, 15b, respectively, and these pair of work rolls 11c, 11d-15c, Cold rolling is performed by passing a steel plate W of a metal plate as a rolled plate during 15d.
[0034]
The rolling speed of each stand 11-15 and the distribution of the gaps (roll gaps) between the work rolls 11c, 11d-15c, 15d are controlled by outputting control signals from the control device 16 through signal lines 25a-25e. Moreover, the value of the rolling load of each stand 11-15 is input into the control apparatus 16 through the input lines 26a-26e. Furthermore, the control device 16 is connected to the input unit 17 and the plate speedometer 18, and is detected by the plate speed, the plate width, the steel type, and the like of the steel plate W set by the input unit 17. The input of actual rolling speed values is accepted.
[0035]
FIG. 2 shows an internal configuration of the control device 16. The control device 16 includes a CPU 20 and a memory 21 therein, stand connection portions 22 a to 22 e serving as connection interfaces with the respective stands 11 to 15, and an input unit 17. And a speed input unit 24 for inputting the rolling speed value detected by the plate speedometer 18.
[0036]
In addition, the stand connection parts 22a-22e are the roll gaps calculated | required by CPU20 so that it may mention later. distribution To adjust each work roll 11c, 11d-15c, 15d distribution A control signal for correcting the work roll bend force is output as a control amount related to the adjustment of the work rolls, and inputs of rolling load values of the work rolls 11c, 11d to 15c, and 15d are received.
[0037]
The memory 21 is a storage means, and the relational expression of the plate width change and the plate crown ratio change before and after rolling of the steel sheet W with the rolling speed as a variable, the plate crown ratio change and the bends of the work rolls 11c, 11d to 15c, 15d. Various mathematical expressions such as relational expressions related to the force correction amount are stored. In addition to the mathematical formula, the memory 21 stores the plate thickness, the plate width, and the steel type of the steel plate W set by the input unit 17, the rolling speed value detected and input by the plate speedometer 18, and the like. Yes.
[0038]
The relational expression of the plate width change before and after rolling of the steel plate W and the plate crown ratio change stored in the memory 21 is as follows:
ΔW = a (V) · Δγ + b (V) (2)
(However, ΔW is a change in sheet width, V is a rolling speed, a (V) is a first function corresponding to the rolling speed, Δγ is a change in sheet crown ratio, and b (V) is a second function corresponding to the rolling speed.)
It is. The plate crown ratio change Δγ is calculated by the following formula (1), and this formula (1) is also stored in the memory 21.
Δγ = Cro / h−Cri / H (1)
(However, Cro / h is the sheet crown ratio after rolling, Cri / H is the sheet crown ratio before rolling)
The rolling speed V in each numerical formula corresponds to the rolling speed value detected by the plate speedometer 18 and input to the control device 16.
[0039]
Furthermore, in the present embodiment, the first function a (V) and the second function b (V) are expressed by the following formulas according to the rolling speed V based on the experimental results for actual rolling and the numerical calculation results by the finite element method or the like. (3) (4) (5) (6) is set, and each set mathematical formula is stored in the memory 21.
a (V) = c · (V−V0) ² + D (when V <V0) (3)
a (V) = d (when V ≧ V0) (4)
b (V) = e · (V−V0) ² + F (when V <V0) (5)
b (V) = f (when V ≧ V0) (6)
[0040]
Note that V0 is a boundary rolling speed at which the relationship between the plate width change and the plate crown ratio change does not depend on the rolling speed. Specifically, in the graph showing the relationship between the rolling speed and the rolling load in FIG. This means the boundary speed at which the rolling load is constant without changing. The boundary rolling speed V0 is automatically calculated by the control device 16 in accordance with the type of rolled sheet, rolling dimensions, rolling conditions, and the like, and is usually a numerical value of about 300 to 500 (m / min).
[0041]
Moreover, c, d, e, and f in the mathematical formulas (3), (4), (5), and (6) are coefficients, and each rolling condition such as the plate thickness, plate width, and steel type of the steel plate W input from the input unit 17 is used. It is a numerical value required for. The units of the coefficients c and e are (min ² / M), and the units of the coefficients d and f are (m).
[0042]
Furthermore, the relational expression between the plate crown ratio change Δγ and the work roll bend force correction amount stored in the memory 21 is:
ΔF = (Δγ−k · ΔP) / g (7)
Where ΔF is the work roll bend force correction amount (work roll roll gap distribution ), ΔP is a change in rolling load before and after the change of the rolling speed, and g and k are for each rolling condition such as the plate thickness, plate width, and steel type of the steel plate W input from the input unit 17. This is the required coefficient. The units of the coefficients g and k are (1 / kN).
[0043]
Further, since the cold rolling apparatus of the present embodiment is the tandem rolling apparatus 10, the plate crown ratio change Δγi before and after rolling at the i-th stand from the upstream side passing through the steel sheet W and the rolling before and after rolling by the tandem rolling apparatus 10. The following formula (8) showing the relationship with the plate crown ratio change Δγ and the formula (9) relating to the bending force correction amount ΔFi of the work roll in each of the stands 11 to 15 are also stored in the memory 21.
[0044]
Δγ = Σ (Δγi) (8)
Σ (gi · ΔFi) = Δγ−Σ (ki · ΔPi) (9)
In Equation (8), Σ (Δγi) is the total of the crown ratio changes in all the stands 11 to 15 of the tandem rolling mill 10, and gi and ki in Equation (9) are input from the input unit 17. It is a coefficient calculated | required for every rolling conditions, such as board thickness of the steel plate W, board width, and steel type.
[0045]
On the other hand, the CPU 20 performs overall control of the control device 16 and calculates the boundary rolling speed V0, the coefficients c, d, e, f, etc., while calculating the sheet crown ratio change and the roll gap. distribution It functions as a means for adjusting. The calculation means of the CPU 20 is based on the mathematical expressions (1) to (9) stored in the memory 21 and makes the plate width change of the steel plate W the same before and after the change of the rolling speed according to the change of the rolling speed. The ratio change is calculated.
[0046]
As specific calculation contents, when the rolling speed is changed from V1 to V2, the calculation means derives the following two expressions by Expression 2.
ΔW1 = a (V1) · Δγ1 + b (V1) (10)
ΔW2 = a (V2) · Δγ2 + b (V2) (11)
However, ΔW1 and Δγ1 are plate width change and plate crown ratio change at the rolling speed V1, and ΔW2 and Δγ2 are plate width change and plate crown ratio change at the rolling speed V2.
[0047]
In order to make the sheet width change the same when the rolling speed is changed from V1 to V2, the relationship of ΔW1 = ΔW2 is established, and therefore the plate crown ratio at the rolling speed V2 from Equations (10) and (11). The change Δγ2 is calculated by the following formula (12).
Δγ2 = {a (V1) · Δγ1 + b (V1) −b (V2)} / a (V2) (12)
By appropriately substituting any one of the formulas (3), (4), (5), and (6) in accordance with the magnitude relationship between the rolling speeds V1 and V2 and the boundary rolling speed V0, the rolling speed is A change in the plate crown ratio that makes the change in the plate width the same before and after the change is calculated.
[0048]
The process of calculating the plate crown ratio Δγ2 corresponding to the rolling speed V2 using the above-described equation (12) will be described below with reference to the graph of FIG. The straight line L1 indicates the proportional relationship between the change in the plate crown ratio and the change in the plate width when the rolling speed is V1, and the straight line L2 indicates the proportional relationship between the change in the plate crown ratio and the change in the plate width when the rolling speed is V2. In the straight line L1, the plate width change is ΔW1 when the plate crown ratio change is Δγ1, and in the straight line L2, Δγ2 corresponding to ΔW2 in which the plate width change is equal to ΔW1 is obtained by Expression (12). Therefore, even if the rolling speed changes to V2, if the plate crown ratio change is Δγ2 on the straight line L2, the plate width change becomes ΔW2 (= ΔW1), and the change in the plate width can be made the same before and after the change of the rolling speed. The fluctuation of the plate width in the plate length direction after rolling can be suppressed.
[0049]
Further, the CPU 20 determines the roll gap of each work roll 11c, 11d-15c, 15d from the change in the plate crown ratio obtained as described above. distribution In order to obtain the correction amount ΔF of the work roll bend force as means for actually adjusting the work roll bending force, the calculated change in the plate crown ratio and the rolling input from each stand are added to the equation (7) stored in the memory 21. A change ΔP of the rolling load when the speed is changed from V1 to V2 is substituted.
[0050]
Further, when the CPU 20 obtains the bending force correction amount ΔFi for each stand in the tandem rolling mill 10, the formula (9) is applied. In this case, since there are a plurality of combinations of ΔFi in Expression (9), the CPU 20 can perform an operation for weighting gi · ΔFi of each of the stands 11 to 15 based on the contents set by the input unit 17. I have to.
[0051]
Next, a series of sheet width control methods and cold-rolled metal sheet manufacturing methods performed by the tandem rolling apparatus 10 described above will be described with reference to the flowchart of FIG.
In order to simplify the description, the process of the flowchart in FIG. 4 is targeted at one stand among a plurality of stands.
[0052]
First, the above-described mathematical expressions (1) to (9) are stored in the memory 21 of the control device 16 (S1). Next, various numerical values and coefficients related to the plate thickness, plate width, steel type and the like of the steel plate W to be rolled by the input unit 17 are input to the control device 16 (S2). After such a preparation stage, the tandem rolling device 10 starts rolling the steel sheet W under the required rolling conditions (S3).
[0053]
After the start of rolling, the control device 16 next determines whether or not the rolling speed has been changed (S4). When the control device 16 does not change the rolling speed, it waits for the next processing until the rolling speed is changed and enters a loop state. Further, when the control device 16 changes the rolling speed, the CPU 20 calculates the change in the plate crown ratio that makes the change in the plate width the same as before the change according to the changed rolling speed, using Equations (2) and (3). (S5).
[0054]
Further, the CPU 20 calculates a correction amount of the work roll bend force based on the calculated change in the plate crown ratio (S6), and a roll gap corresponding to the calculated correction amount of the work roll bend force. distribution Then, the work roll is adjusted to perform rolling (S7). After rolling in such a state, the control device 16 determines whether or not to end the rolling (S8). When the rolling is not finished, the control device returns to the step (S4) as to whether or not the rolling speed has been changed, and thereafter the same processing as described above is performed. Moreover, when ending rolling, it ends as it is.
[0055]
Thus, the cold-rolled sheet manufactured by the tandem rolling apparatus 10 by the sheet width control method and the cold-rolled metal sheet manufacturing method according to the present invention is a rate at which the sheet width varies in the sheet length direction compared to the conventional one. The finish is improved with improved plate width accuracy.
[0056]
Next, in order to confirm the fluctuation | variation of the board width of the rolled steel plate with the board width control method and cold-rolled metal plate manufacturing method which concern on this invention, verification by the following examples was performed.
In the present example, a tandem rolling apparatus 30 in which the four-stage rolling stands shown in FIG. The steel plate W rolled by the tandem rolling device 30 has a plate thickness before rolling of 4.5 (mm), and is an ordinary steel having a uniform plate width of 1200 (mm) that reaches the full length by performing edge trimming before rolling. Was used. This ordinary steel was cold-rolled to a thickness of 1.0 (mm) by a tandem rolling device 30 to produce a cold-rolled steel sheet. As the rolling oil, an emulsion-type mineral oil-based rolling oil was used.
[0057]
The tandem rolling device 30 uses the fifth stand to control the work roll bend force without the control device 36 controlling the correction amount of the work roll bend force only in the fifth downstream side of the tandem rolling device 10 shown in FIG. In order to satisfactorily finish the shape, the bend force of the work roll is controlled independently, and the configuration of the other input unit 37, plate speedometer 38 and the like is the same.
[0058]
The roll diameters of the work rolls 31c, 31d to 35c, 35d of the first stand 31 to the fifth stand 35 of the tandem rolling device 30 are 400 (mm), and the roll diameters of the backup rolls 31a, 31b to 35a, 35b are 1400 (mm). The roll body lengths of the work rolls 31c, 31d to 35c, 35d and the backup rolls 31a, 31b to 35a, 35b were set to 1800 (mm). In addition, the rolling reduction of the first stand 31 to the fourth stand 34 is set to 30%, the rolling reduction of the fifth stand 35 is set to 5%, the rolling speed at the high speed part is 800 (m / min), and the rolling speed at the low speed part is set. The rolling speed was set to 100 (m / min).
[0059]
Further, in the formulas (3) and (5) stored in the memory of the control device 36 of the tandem rolling device 30, in this embodiment, the boundary rolling speed V0 is set to 500 (m / min) from the results of actual rolling experiments and numerical calculations. ), The coefficient c is -3.9 × 10 ^-7 (Min ² / M), the coefficient d is 1.85 × 10 ^-3 (M), coefficient e is 6.9 × 10 ^-9 (Min ² / M), the coefficient f is -1.4 × 10 ^-3 (M).
[0060]
Further, in calculating the work roll bend force correction amount ΔFi of the work rolls 31c, 31d to 34c, 34d, in this embodiment, different weights wi are attached to the first stand 31 to the fourth stand, respectively. Thus, the occurrence of problems due to deterioration of the plate shape on the downstream side where the plate thickness is reduced is prevented. The weight w1 of the first stand 31 was 0.6, the weight w2 of the second stand 32 was 0.8, the weight w3 of the third stand 33 was 1.0, and the weight w4 of the fourth stand 34 was 2.0.
[0061]
In addition, the gi · ΔFi of the mathematical formula (9) is obtained by subtracting g1 of the first stand from −5.67 × 10 from the result of numerical calculation performed in advance before the actual rolling. ^-Five (1 / kN), g2 of the second stand is −4.92 × 10 ^-Five (1 / kN), g3 of the third stand is −4.55 × 10 ^-Five (1 / kN), g4 of the fourth stand is −4.18 × 10 ^-Five (1 / kN).
[0062]
Therefore, in this embodiment, the following formula (13) is established by setting the values obtained by multiplying the weights w1 to w4 by gi · ΔFi to be uniform from the first stand 31 to the fourth stand 34.
w1 · g1 · ΔF1 = w2 · g2 · ΔF2 = w3 · g3 · ΔF3 = w4 · g4 · ΔF4 (13)
By calculating the simultaneous linear equations of the equation (13) and the above equation (9) by the CPU of the control device 36, the correction amount ΔFi of the work roll bend force for each stand is obtained, and the correction amount thus obtained is calculated. The roll gap of the work rolls 31c, 31d to 34c, 34d with ΔFi distribution The rolling was carried out by adjusting the.
[0063]
In such rolling, the sheet speed on the exit side of the tandem rolling device 30 when the rolling speed is accelerated from 100 (m / min) to 800 (m / min) and then decelerated to 100 (m / min). The measured values of the work roll bend force of each stand from the first stand 31 to the fourth stand 34, and the width of the outgoing steel plate after rolling by the tandem rolling device 30 are measured with an optical plate width meter. It is shown in FIG.
[0064]
Further, as a comparative example with respect to the above-described embodiment, the same steel plate as described above is used with a rolling speed of 100 (m / m) using a 5-stand tandem rolling device according to the conventional sheet width control method and cold-rolled metal sheet manufacturing method. min) to a rolling speed of 800 (m / min), and then reduced to 100 (m / min) for rolling. FIG. 7 shows measured values of the plate speed on the exit side of the tandem rolling apparatus in the rolling of this comparative example, the work roll bend force of each stand from the first stand to the fourth stand, and the plate width of the steel plate after rolling. ing.
[0065]
The plate width of the steel plate according to the present embodiment is adjusted by appropriately correcting the work roll bend force of each of the stands 31 to 34 even when the exit side plate speed of the tandem rolling device is accelerated and decelerated from FIG. gap distribution By appropriately adjusting the thickness, the fluctuation of the plate width was kept within a range of about ± 0.3 mm from beginning to end, and the fluctuation of the plate width could be suppressed.
[0066]
On the other hand, the measured value of the sheet width of the steel sheet according to the comparative example changes in the direction in which the sheet width shrinks because the correction of the bending force of the work roll is not appropriate when the sheet speed on the exit side of the tandem rolling device is accelerated from FIG. Also, when the plate speed was reduced, the work roll bend force was not corrected, so the plate width changed.
[0067]
The reason why the variation in the plate width is different is that the change in the work roll bend force from the first stand to the fourth stand is different between this embodiment and the comparative example because the control method is different. Can be mentioned. In particular, in both the first stand to the third stand, the form of transition of the work roll bend force when the speed changes and the numerical value of the work roll bend force when the plate speed is 800 m / min are greatly different. I can read.
[0068]
From the examples and comparative examples described above, the material to be rolled is rolled by a cold rolling apparatus to which the sheet width control method and the cold-rolled metal sheet manufacturing method according to the present invention are applied. It was found that fluctuations in the plate width in the plate length direction can be suppressed. In addition, the sheet width control method, the cold-rolled metal sheet manufacturing method, and the cold rolling apparatus according to the present invention, in addition to the tandem rolling apparatus having a work roll bending apparatus capable of correcting the work roll bend force, The present invention can be applied to an apparatus that can change the distribution of the roll gap, such as a roll cloth rolling apparatus and a roll shift rolling apparatus.
[0069]
【The invention's effect】
As described in detail above, in the first invention, the second invention, and the third invention, the calculation for obtaining the change in the plate crown ratio that makes the change in the plate width constant according to the rolling speed is performed, and the calculation result is Based on roll gap distribution By adjusting the above, even if the rolling speed changes, fluctuations in the sheet width after rolling can be suppressed.
[0070]
In the fourth invention, in order to suppress the fluctuation of the sheet width before and after the change of the rolling speed, by defining the sheet crown ratio change and the sheet width change based on the mathematical formula, the sheet width change according to the rolling speed. It is possible to reliably calculate a constant plate crown ratio change.
In the fifth invention, the calculation corresponding to the required rolling conditions is performed by applying mathematical formulas according to the rolling conditions such as the type of rolled sheet and the rolling dimensions to the mathematical formulas of the fourth invention. Can do.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a tandem rolling apparatus according to an embodiment of the present invention.
FIG. 2 is an internal configuration diagram of a control device in the tandem rolling apparatus of the embodiment.
FIG. 3 is a graph showing a control state of a change in plate crown ratio and a change in plate width when the rolling speed is changed.
FIG. 4 is a flowchart showing a series of processes related to suppression of fluctuations in plate width.
FIG. 5 is an overall configuration diagram of a tandem rolling apparatus according to an embodiment.
FIG. 6 is a graph showing a state of plate speed, work roll bend force from the first stand to the fourth stand, and plate width variation in the example.
FIG. 7 is a graph showing a plate speed, a work roll bend force from the first stand to the fourth stand, and a state of plate width variation in a comparative example.
FIG. 8A is a plan view of a rolled steel sheet with a varying sheet width, and FIG. 8B is a plan view of the rolled steel sheet with a non-varied sheet width.
9A is a front view showing a rolled state of a steel plate by a rolling mill, and FIG. 9B is a plan view showing a change in the plate width before and after rolling by the rolling mill.
FIG. 10 is a graph showing problems in a conventional control method.
FIG. 11 is a graph showing the relationship between rolling speed and rolling load.
FIG. 12 is a schematic view showing the plate shape in the cross-sectional direction during low-speed rolling and high-speed rolling.
[Explanation of symbols]
10 Tandem rolling equipment
11-15 The 1st stand-the 5th stand
11c, 11d-15c, 15d Work roll
16 Control device
20 CPU
21 memory
W steel plate

Claims (5)

In the plate width control method for controlling the plate width of the rolled plate by adjusting the roll gap distribution of the stand in relation to the plate crown ratio of the rolled plate,
Storing the relationship between the plate width change before and after rolling the plate to be rolled and the plate crown ratio change according to the rolling speed;
Based on the stored relationship, calculating a plate crown ratio change that makes the plate width change the same according to the rolling speed;
Adjusting the roll gap distribution on the basis of the calculated change in the plate crown ratio. In stand Adjust the roll gap distribution in relation to the strip crown ratio of the rolled sheet, the cold-rolled metal sheet manufacturing method for cold rolling a rolled plate,
Storing the relationship between the plate width change before and after rolling the plate to be rolled and the plate crown ratio change according to the rolling speed;
Based on the stored relationship, calculating a plate crown ratio change that makes the plate width change the same according to the rolling speed;
Adjusting the roll gap distribution based on the calculated plate crown ratio change. By adjusting the roll gap distribution of the stand in relation to the plate crown ratio of the plate to be rolled, in the cold rolling apparatus for cold rolling the plate to be rolled by controlling the plate width,
Storage means for storing the relationship between the change in the plate width before and after rolling the plate to be rolled and the change in the plate crown ratio according to the rolling speed;
Based on the relationship stored by the storage means, calculating means for calculating a plate crown ratio change that makes the plate width change the same according to the rolling speed;
And a means for adjusting the roll gap distribution based on a change in the plate crown ratio calculated by the calculating means. The relationship is
ΔW = a (V) · Δγ + b (V)
(However, ΔW is a change in sheet width, V is a rolling speed, a (V) is a first function corresponding to the rolling speed, Δγ is a change in sheet crown ratio, and b (V) is a second function corresponding to the rolling speed.)
The cold rolling apparatus according to claim 3. The first function a (V) is
a (V) = c · (V−V0) ² + d (when V <V0)
a (V) = d (when V ≧ V0)
And
The second function b (V) is
b (V) = e · (V−V0) ² + f (when V <V0)
b (V) = f (when V ≧ V0)
(However, V0 is the boundary rolling speed with respect to the relationship between the plate width change and the plate crown ratio change, and c, d, e, and f are coefficients corresponding to the type and rolling dimensions of the plate to be rolled).
The cold rolling apparatus according to claim 4.

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