JP3172613B2 - Meander control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling the operation of a rolling mill train in a tandem rolling operation of a metal sheet to ensure stable threadability of a rolled material during rolling.

[0002]

2. Description of the Related Art Tandem rolling of a metal plate is a process capable of mass-producing a high-precision thin metal sheet. Since tension can be applied to a rolled material between rolling mills constituting a tandem rolling mill row, it is very difficult. Stable rolling operation is possible. When tension is applied to the rolled material, for example, even if there is a certain deviation from the optimum value in the reduction leveling, it does not become the difference between the left and right elongation rates as it is, Since the difference between the left and right sides is suppressed, it is unlikely to be directly linked to a passing board accident. However, since the forward or backward tension cannot be applied to the leading end and the trailing end of the rolled material, the stabilizing effect due to the tension is reduced by half, and a passing-through accident is likely to occur. In particular, when passing through the rear end, a pass-through accident called a tail narrowing often occurs, and a rolling-down control called a meandering control or a tail narrowing control is conventionally performed.

[0003] In the following description, the working side and the driving side are often simply expressed by "left and right". “Left” means the working side, and “right” means the driving side.

It is considered that the tail-drawing is mainly caused by the meandering of the material caused by a difference in elongation between the left and right (work side and drive side) near the rear end of the rolled material. The conventional method of the meandering control is to execute the control of the left-right difference of the rolling reduction value of the rolling mill, that is, the leveling control from the time when the rear end of the material exits the immediately preceding rolling mill. As the detection end at this time, a detection signal of the off-center amount of the plate by the meandering sensor or the difference between the left and right rolling loads of the rolling mill is used.

[0005]

In the conventional method of the meandering control as described above, the control is substantially started from the time when the rear end of the rolled material exits from the immediately preceding rolling mill. The time is so short that it may not be enough to prevent the squeezing. If there is a deviation from the optimum value in the rolling leveling of the rolling mill, when the rear end of the rolled material exits the immediately preceding rolling mill, the backward tension that has been applied up to that point disappears, and the right-left difference in the tension is reduced. Since the compensation effect due to is lost, sudden meandering starts, and it is often too late to start the rolling leveling control after the symptom appears.

SUMMARY OF THE INVENTION It is an object of the present invention to more effectively prevent tail squeezing.

[0007]

According to the present invention, there is provided:
In general, instead of starting the control from the time when the rear end of the rolled material exits the immediately preceding rolling mill, in a steady rolling state before reaching the rear end of the rolled material, the rolling leveling of each rolling mill in the tandem rolling mill row is performed. And an optimal state in which the right-left tension difference becomes substantially zero. The biggest change caused by the trailing end of the rolled material leaving the immediately preceding rolling mill is, of course, the loss of back tension. Therefore, if sudden meandering starts at this time, it means that the rolling leveling of the rolling mill has deviated from the optimum value, and this has been compensated for by the left-right difference in the rear tension. From this, it is thought that keeping the right-left difference in tension between the rolling mills as close to zero as possible during the steady rolling state before reaching the rear end of the rolled material will be the decisive factor in preventing the buttocks drawing accident. . For this purpose, the operation of detecting or estimating the difference between the left and right tension applied to the rolled material between the rolling mills and making the difference close to zero may be performed. However, in the tandem rolling state, the rolling leveling operation of each rolling mill affects the rolling state in all rolling mills through the tension distribution between the rolling mills, so that even if there is only one lateral difference in tension. The rolling leveling correction must generally be made for all rolling mills.

Accordingly, in a first aspect of the present invention, in the steady rolling state by the tandem rolling mill train, the working side rolling load during rolling, and sampled substantially the same time the driving side pressure rolling load and roll peripheral speed, of Based on the data, estimate the left-right difference in tension between each rolling mill acting on the rolled material, with the goal of making the left-right difference in the tension zero,
The difference between the left and right set values of the rolling reduction of each rolling mill is controlled.

[0009] For example, the difference between the left and right sheet thicknesses on the i-th stand exit side of the tandem rolling mill row composed of N rolling mills, ie, the sheet wedge amount _hdfi, is the rolling _level difference _Sdfi , the lateral difference between the rolling load distributions, ie, the line load difference. p _dfi and the distance from the mill center at the center of the width of the rolled material sheet can be expressed by the following equation using the material off-center amount x _ci representing the working side as positive. _{h dfi = (b / a Bi} ) S dfi + D i p dfi + in _{E i x ci (i = 1~N} ) ··· (1) where, b is the rolled material strip width, a _Bi is up roll pressure fulcrum during distance, E _i is the influence coefficient or first type parallel rigid weight material off center on the plate wedge, D _i is the influence coefficient or second type parallel rigid line load difference p _dfi on the plate wedge amount h _dfi It is.

In general, the suffix df indicates a difference between left and right, and indicates a value obtained by subtracting a value on the drive side from a work side.

The equation (1) purely represents the deformation characteristics on the rolling mill side, and the linear load difference p _dfi in the equation (1)
Is expressed as the following equation as the left-right difference of the rolling load equation mainly depending on the conditions of the rolling material side. p _dfi = p _dfi [k _dfi , _{hdf (i-1)} , _hdfi , _{σdf (i-1)} , _σdfi ] (i = 1 to N) (2) where k _dfi is The left-right difference in the deformation resistance of the rolled material, σ _dfi, is the left-right difference in the i-th stand exit side tension, and equation (2) is given as the difference between the working side and the drive side in the rolling load formula given by the rolling theory. The main factor that determines the tension difference σ _dfi is the left-right difference f _dfi of the advanced coefficient and the left-right difference f
a _Bdfi, they are given as a difference between right and left of the developed coefficients formula given in the rolling theory and backward coefficients formula are those dependent on by <br/> Una factors follows. f _dfi = f _dfi [k _dfi , _{hdf (i-1)} , _hdfi , σ _{df (i-1)} , σ _dfi ] (i = 1 to N) (3) f _bdfi = f _bdfi [ k _dfi , _{hdf (i-1)} , _hdfi , _{σdf (i-1)} , _σdfi ] (i = 1 to N) (4) Next, at the time of data sampling, a sufficiently steady rolling state is obtained. Assuming that this is realized, the following equation is obtained from the condition that no new tension fluctuation occurs between the stands. V _{R (i + 1)} f _{bdf (i + 1)} = V _Rifdfi (i = 1 to N−1) (5) where V _Ri is the roll peripheral speed of the i-th stand. In addition to equation (5), it is normal that there is no buckling of the material entering the tandem rolling mill or rotation as a whole in a plane, so the following equation also holds. f _bdf1 = 0 (6) From the steady rolling conditions, the following formula is obtained by taking into account the constant mass flow conditions before and after each rolling mill. _{h df (i-1) v} (i-1) + v df (i-1) h (i-1) = h dfi v i + v dfi h i (i = 1~N) where, V _i is the i It is the rolled material speed on the exit side of the stand,
h is the average sheet thickness of the rolled material. In deriving the above equation, a condition is used that h _df is smaller than h and v _df is a first-order minute quantity compared to v, and under this condition, h is a plate at the center of the plate width. It may be thick. The following equation is obtained by dividing both sides of the above equation by the roll peripheral speed V _Ri of the i-th stand. _{h df (i-1) f} bi + f bdfi h (i-1) = h dfi + f dfi h i (i = 1~N) ··· (7) In addition, there is a rolling load as data that can be measured during rolling However, this is detected by a rolling load measuring device, that is, a load cell, which is mounted at the position of the supporting roll pressing fulcrum on the working side and the driving side. Then, when the difference between the left and right values measured by the load cell of the i-th stand is P _dfi , this has the following relationship between the linear load difference p _dfi and the material off-center amount x _ci . P _dfi = ^[b 2 / (6a _{Bi)] p dfi + (2 / a Bi} ) P i x ci + (a Wi / a Bi) F dfi (i = 1~N) ··· (8) , where , F _dfi is the difference between left and right roll bending force, a _Wi
Is the distance between the fulcrums of the work rolls.
_{Since dfi} = 0, in this case, the third term on the right side of Expression (8) is unnecessary.

The present invention is based on the above formulas (1) to (8), in which the right and left difference of the tension between the stands is determined and the rolling down control is performed to make this difference zero. This is the basic idea. In this sense, the current rolling state must first be grasped.

Among the variables appearing in the above equation system, rolling mill dimensions a _Bi , a _Wi , strip width b, roll peripheral speed V _Ri , rolling load P _i , right and left difference P _{dfi of} rolling load, left and right of roll bending force The difference F _dfi , advanced coefficient f _i , backward coefficient f _{bi, and the} like are known quantities or quantities that can be measured or estimated by setting calculations or the like. The unknowns excluding these variables are listed as follows. _{S dfi (i = 1~N),} h dfi (i = 0~N), p dfi (i = 1~N), x ci (i = 1~N), f dfi (i = 1~N), f _bdfi (i = 1 to N), k _dfi (i = 1 to N), σ _dfi (i = 0 to N) (9) When all the above are unknown, there are 8N + 2 unknowns. Will be. In contrast, equations (1) to (8)
Since the number of equations is 7N, the number of unknowns is N + 2.
Unless it is reduced by the number of pieces, it is impossible to grasp the current state of the meandering of tandem rolling. Therefore, the above eight sets (8
At least N + 2 values of the (× N) unknowns need to be measured or estimated by another method, and various embodiments can be considered depending on the method of this selection. However, at least the roll peripheral speed, the rolling load, and the difference between the left and right sides of the rolling load need to be measured simultaneously at the same time.
For this reason, simultaneous point sampling of the rolling load and roll peripheral speed data on the working and driving sides during rolling is an essential requirement of the present invention.

As an example, of the eight sets (8 × N) of unknowns, the input side plate wedge h _dfO and the _output side plate wedge h _dfO
dfN is measured and the deformation resistance left and right difference k _dfi (i = 1
To N) will be described by estimating the temperature through measurement in the width direction of the sheet.

In the case of cold rolling, which is the subject of the second invention of the present application, in most cases, there is no left-right difference in deformation resistance, and k _dfi = 0 (i = 1 to N) may be used. . Therefore, in this case, if the measurement of the wedges on the entrance and exit sides of the tandem rolling mill row is performed, the remaining unknowns become 7N, and the values of all the unknowns are obtained by solving the equations (1) to (8). It becomes possible to grasp.
Since the right-left difference σ _dfi of the tension calculated in this way is not generally zero, a leveling operation basic amount ΔS _dfi for making the difference zero is next to be calculated. First, the leveling S recognized by solving equations (1) to (8)
The value of _dfi is set as S ¹ _dfi . The value of S ¹ _dfi should basically correspond to the current reduction set value, but as can be seen from equation (1), S _dfi is the current rolling condition, p _dfi = 0, This is an idealized leveling such that h _dfi = 0 under the condition of x _ci = 0. Generally, the actually measured rolling leveling value is the error of the zero point of the rolling reduction value and the housing of the rolling mill. -Since the amount differs by the left-right difference of the deformation of the rolling system, it is treated as an unknown here. Now, the goal is σ _dfi = 0 (i
= 0 to N), and this condition is expressed by Expression (1).
(8). By doing so, the number of unknowns is reduced by N + 1. On the other hand, among the current measurement values, the most affected by the change in σ _dfi is the left and right difference P _dfi of the rolling load and the exit plate wedge h _dfN . P _dfi and h _dfN may be newly added as unknowns to solve the equation systems of equations (1) to (8). _Assuming that the reduction leveling S _dfi thus _obtained is S ² _dfi , the basic leveling operation amount ΔS _dfi for realizing σ _dfi = 0 is calculated by the following equation. ΔS _dfi = S ² _dfi −S ¹ _dfi (i = 1 to N) (10) The ΔS _dfi calculated here is the left-right difference σ _{dfi in} tension.
At a stroke, and it goes without saying that in actual control, conventional control means such as multiplying the basic operation amount ΔS _dfi by a tuning factor is used. However, since this control uses the interdependency of each rolling mill in the steady rolling state, it is preferable that the cycle time is longer than the time for transferring the material from the first stand to the last stand of the tandem rolling mill.

Now, in the case of hot rolling which is the subject of the third invention of the present application, since the temperature distribution in the sheet width direction of the rolled material is not necessarily symmetrical, the left and right difference k _dfi of the deformation resistance is not necessarily zero. Not. Therefore, the temperature of the rolled material at the entrance and / or the exit side of the tandem rolling mill row is measured at two or more points in the strip width direction, and based on the data, the strip width of the rolled material at the time when the rolled material reaches each rolling mill is measured. The estimation calculation of the directional temperature distribution is performed, and the estimation calculation of the left-right difference k _dfi of the deformation resistance is performed. After that,
As in the case of the cold rolling described above, the right-left difference in tension between the rolling mills is made zero by measuring the left-right difference in rolling load, roll peripheral speed, and the amount of sheet wedge at the entrance and exit of the tandem rolling mill row. Leveling operation basic amount for the operation can be obtained.

In the above, it has been premised to calculate indirectly the right-left difference in tension during rolling.
The fifth invention uses means for directly detecting this. That is, this is an embodiment in which rolls for detecting the tension of the rolled material are arranged between each rolling mill in the tandem rolling mill row. For example, in the case of a hot tandem mill, load cells are provided on the left and right support portions of the looper roll. This enables direct detection of the tension difference. However, the looper load cell load difference R _dfi includes the influence of the material off-center in addition to the tension difference, and the following relational expression is established. R _dfi = _{^{[{b 2 / (6a Li)}} } σ dfi + (2 / a Li) σ i bΧ ci ] _{(sinθ i + sinθ i + 1} ) h i (i = 1~N-1) ··· ( 11) Here, R _dfi is the left-right difference of the load in the vertical direction corrected for the looper angle, a _Li is the distance between the fulcrum points of the looper roll, θ _i and θ _{i + 1} are the _{i- th} and _{i + 1-} th boundaries from the looper roll.
Angle rolled plate surface of the stand side forms with the horizontal plane, h _i is the i
Stand exit side plate thickness, Χ _ci is the material off-center amount at the looper position, and approximately, i-th and i + 1-th
Material off-center amount at stand x _ci , x _{c (i + 1)}
, Ie, the following equation. Χ _ci = β _i x _ci + (1−β _i ) x _{c (i + 1)} (12) For simplicity, in the following discussion, equation (11) is replaced with equation (1)
It is assumed that 2) is already substituted, and that Χ _ci and equation (12) are not counted as new variables and equations.

In the case of a cold tandem rolling mill, a tension roll is used instead of a looper roll, but the basic principle of tension detection is the same, and the equation (11) can be used in exactly the same manner. When the equation (11) is added to the equations (1) to (8), the number of equations becomes 8N−1, which means that there are three missing numbers for 8N + 2 unknowns.

In the case of cold rolling which is the object of the fourth invention of the present application, as described above, k _dfi = 0 (i = 1 to 1)
N), the number of unknowns is 7N + 2. Therefore, in the case of a cold tandem mill having three or more rolling mills, the number of unknowns is smaller than the number of equations, and a unique solution or a least square solution can be obtained. However, since the left-right difference of the load cell output of the tension roll greatly changes by _setting the right-left difference σ _{dfi of the} tension to zero, when σ _dfi = 0 (i = 0 to N), R _dfi along with the right-left difference of the rolling load is _set. Must be unknown, and the number of equations is insufficient. in this case,
When R _dfi (i = 1 to N−1) is included, the number of unknowns is 8
N. Therefore, since the number of equations is insufficient by one, the thickness of the tandem rolling mill row, which is thicker and easier to measure, is measured at two or more points in the width direction of the tandem rolling mill.
_What is _necessary is _just to use an actual measurement value for _dfO . In this case, the number of equations is larger than the number of unknowns in the first equation system for grasping the current situation, but a more accurate solution can be obtained by calculating the least squares solution using the extra equation system. Can be

In the case of a hot tandem rolling mill train equipped with a looper load cell, which is the subject of the fifth invention of the present application,
The number of equations is 8N-1 with respect to 8N + 2 unknowns, and there are three more unknowns. Therefore, the entrance and exit side plate thickness of the tandem rolling mill row is measured at two or more points in the plate width direction,
_Using the measured values for the entrance side plate wedge _hdfO and the exit side plate wedge _hdfN , the temperature of the rolled material on the entrance side and / or exit side of the tandem rolling mill row is measured at two or more points in the sheet width direction, and based on these data. At least one of the left and right deformation resistances in each rolling mill, for example, k _df1 or k _df1
Estimate _dfN . By doing so, the equation system can be solved, and the current state of the meandering phenomenon can be grasped. Next, since the value of k _dfi (i = 1 to N) is not considered to greatly change from the value already obtained,
This value is fixed, the right-left difference in tension σ _dfi (i = 0 to N) is set to zero, the left-right difference P _dfi (i = 1 to N) in the rolling load, and the left-right difference R _dfi (i = 1 to 1) in the looper load cell load. N-1)
_Is newly unknown and the system of equations (1) to (8) and (11) are simultaneously solved to obtain the leveling S _{dfi obtained.}
The leveling operation amount basic amount ΔS _dfi may be obtained from the amount of change in the value.

In the above description, each invention of the present application has been described with reference to typical examples. As a variation of these examples, a measured value or an estimated value is used for what was treated as an unknown in the above description. It goes without saying that the gist of the present invention does not change even if it is handled as a known amount. FIG. 1 shows the outline of the algorithm of the meandering control method of the present invention. The flow of the meandering control method of the present invention will be confirmed again according to FIG.

As the measured values, the difference between the right and left of the rolling load and the peripheral speed of the roll are indispensable data. It is treated as a known quantity by the estimated value, and the equation system at the time of steady rolling is solved, and the current value of the right-left difference in tension and the current value of the reduction level are obtained. Next, the left-right difference of the tension is set to a target value, that is, zero, the left-right difference of the rolling load is set as a new unknown, the equation system is solved again to obtain the target value of the reduction level, and the difference between the current reduction level value and the reduction leveling is calculated. The basic operation amount is calculated, and the value on which the tuning factor is loaded is used as the control output of the reduction leveling. By the way, in each of the above-mentioned inventions of the present application, the measurement of the left and right of the rolling load is an essential requirement, and therefore, the detection of the rolling load by the rolling load measuring device on the working side and the driving side and the difference between the left and right must be calculated. However, at this time, the accuracy of the rolling load measuring device of each rolling mill constituting the tandem rolling mill row is very important.

Therefore, in the sixth invention of the present application, the load cell is calibrated with high accuracy by using a hydraulic roll bending device from the viewpoint of examining the load acting between the upper and lower work rolls. Implement an invention. In the following, “sensitivity” refers to a proportional coefficient between current or voltage and load. FIG. 2 shows a side view of a typical plate rolling mill. The rolling mill in FIG. 2 is a four-high rolling mill, in which work rolls 8-1 and 8-2 are supported by reinforcing rolls 9-1 and 9-2, and an upper reinforcing roll 9-1 is a reinforcing roll balancing device. It is pressed against the rolling load measuring device 1 and the rolling device 12 by 6-1 and 6-2, and is configured to follow the movement of the rolling device. In addition, the increment work roll bending devices 2-1 and 2-2 and 3-1 and
3-2 also functions as a roll balance, and works rolls 8-1 and 8-2 via work roll chocks 10-1 and 10-2 to reinforce rolls 9-1 and 9-2.
Pressed against. FIG. 2 also shows, for reference, the dicing operation roll bending devices 4-1 and 4-2 and 5-1 and 5-2 for applying a force in the direction opposite to the roll balance. The calibration method of the rolling load measuring device of the present invention is based on the premise that a roll bending force in the direction of opening the upper and lower work roll gap is applied as a resultant force, and the decrease work roll bending device is not an essential requirement. The work roll bending device shown in FIG. 2 is a hydraulic type, and at least the rolling load measuring device 1 is used.
The side work roll bending devices 2-1 and 2-2 include:
Pressure measuring device 14 for hydraulic oil supplied to working cylinder
It is assumed that is equipped. In such a rolling mill, when the non-rolling operation is performed, the roll bending device 2-1 and the upper and lower operation roll gaps are opened as shown in FIG.
The work roll bending force is calculated from the actual value of the hydraulic pressure by the pressure measuring device 14, the effective cross-sectional area of the working cylinder, and the number of cylinders by applying a load of two or more levels by 2-2, and measured by the rolling load measuring device 1 The corresponding relationship with the applied load is obtained as data. With the roll gap open, the work roll body is unloaded,
The load applied by the work roll bending device is directly transmitted to the rolling load measuring device 1 except for the weight of the roll and the spindle. Therefore, the applied roll bending force and the value measured by the rolling load measuring device 1 should ideally coincide with each other except for the bias due to the weight of the roll, the spindle, and the like. Calibrating the zero point or both the zero point and the sensitivity is the basic concept of the rolling load measuring device calibration method which is a constituent feature of the sixth invention of the present application.

FIG. 3 shows an example of data obtained by the sixth invention of the present application using the No. 6 stand of the actual hot strip mill finishing mill. In FIG. 3, the data of the load and the unloading are all plotted with five levels of the roll bending force load. In the figure, there is data with a significant difference in the output of the rolling load measuring device for almost the same value of the roll bending force, but this is the difference between when the load is applied and when the load is unloaded. It is considered that the hysteresis caused by the phenomenon became apparent. As one of the prior arts, there is a method of adjusting the zero point of a rolling load measuring device by applying a constant roll balance force. When checking the zero point of the rolling load measuring device by this, as shown in FIG. There is a risk that the maximum value of the hysteresis becomes an error of the zero point as it is. On the other hand, as shown in FIG. 3, data for a plurality of load levels are collected, and the influence of such hysteresis is minimized by performing data processing of, for example, linearly approximating the data by the least squares method. Becomes possible. In general, the pressure sensor of the hydraulic circuit used for the pressure measuring device 14 is much smaller and less expensive than the rolling load measuring device 1, and the pressure sensor whose accuracy has been sufficiently checked is periodically replaced. Also, it is easy to introduce several sensors in the same hydraulic circuit and to check the accuracy with each other, and the accuracy control is very easy. Therefore, it is possible to control the accuracy of the rolling load measuring device which is very expensive and cannot be easily replaced by using this. This is a great profit in practical operation.

In FIG. 3, the least squares approximation of the data including the gradient of the straight line is performed for the purpose of calibrating both the zero point and the sensitivity of the rolling load measuring device. However, the purpose is to calibrate only the zero point. If so, a linear approximation with the gradient fixed at 1 as shown in FIG. 4 may be performed. For example, when both the zero point and the sensitivity are calibrated, the following equation is obtained by linear approximation of the data in FIG. P _W = 1.039F-59.6 (13) P _D = 1.022F-82.9 (14) Here, P _W and P _D are output values of the rolling load measuring devices on the working side and the driving side, respectively. F is the roll bending force, and the unit is both tonf. In the present invention, since the value of F is considered to be a sufficiently calibrated and accurate value, values obtained by evaluating the true load applied between the upper and lower work rolls on the working side and the driving side are Q _W and Q _D. Then, equation (13),
From (14), Q _W and Q _D can be obtained from the measured values P _W and P _D by the following equations.

Q _W = (P _W +59.6) /1.039 (15) Q _D = (P _D +82.9) /1.022 (16) The measurement or calculation was performed in this manner. Since the values of Q _W and Q _D during rolling include the roll bending force F, if it is desired to estimate the true load acting between the rolled material and the work roll, Q _W and Q _D Is subtracted from the measured value of the roll bending force F at each time. Further, instead of performing the operations as in the equations (15) and (16), substantially the same sensitivity and bias adjustment may be electrically performed.

If the purpose is only to calibrate the zero point, FIG.
The following relationship is obtained from the linear approximation in which the gradient is fixed to 1. P _W = F−55.1 (17) P _D = F−80.4 (18) Therefore, the true load Q including the roll bending force
_W and Q _D are obtained from the measured loads P _W and P _D by the following equations. Q _W = P _W +55.1 (19) Q _D = P _D +80.4 (20) In the above procedure, the weight of the roll and the spindle is not mentioned at all, but physically. Is between the roll bending force F and the value detected by the rolling load measuring device 1,
There should be a bias for the weight of the rolls and spindles, etc. However, since these values are constant unless the rolls are replaced, according to the original purpose of roll load detection that the load acting between the upper and lower work rolls has been detected, this bias is applied to the bias of the roll load detector itself. The idea is to absorb in minutes. Of course rolls and the load Q _W weight fraction accurately consider the roll bending force F and true to the spindle such, it is also possible to describe the relationship between Q _D, even in this case, the basic of the procedure is the same is there.

By performing the calibration of the rolling load measuring device with high precision as described above, the reliability of the measured value of the left-right difference of the rolling load during steady rolling becomes very high, and based on this measured value, The accuracy and stability of the meandering control of the first invention of the present application are improved.

[0029]

【Example】

In the rolling tandem cold strip mill consisting of (Example 1) 3 group or a rolling mill, rolling load left-right difference P _dfi during rolling, the same time data of the tension roll reaction force left-right difference R _dfi and roll peripheral speed V _i Collect. If these data are obtained, assuming k _dfi = 0 (i = 1 to N), the number of unknowns among the variables (formula (9)) is 7N + 2. In contrast, the number of equations is
1N, including 8N−1, by linearly approximating all the equation systems of equations (1) to (8) and (11),
The unknowns among the variables (the above equation (9)) can be accurately obtained by the least square method. When the value of the left-right difference σ _dfi of the tension obtained in this way exceeds the allowable value, the reduction of the _rolling reduction is performed. When _{calculating the rolling} leveling operation basic amount ΔS _dfi , as described above, σ _dfi
= 0 (i = 0 to N) to solve the equation system. At this time, P _dfi and R _dfi become new unknowns.

Therefore, the number of unknowns is 8N,
One more than the number of equations. At this time, the method of using the measured values of the entrance and exit side plate wedges is defined in the fifth invention of the present application, but this embodiment is an example in which the accuracy of the exit side plate thickness measuring device is not sufficient. . In other words, in order to quantitatively examine the meandering state of the sheet through the sheet thickness deviation, a very high sheet thickness detection accuracy is required, and in particular, the detecting device on the output side of the tandem rolling mill where the sheet thickness becomes thin satisfies this. It is not possible. Even in this case, since the entrance side plate thickness is relatively thick, the detection accuracy is usually at a sufficiently satisfactory level, and the detected value can be used as _hdfo . As a result, the number of unknowns becomes 8N-1, and all the solutions can be obtained by solving the above equation system. In addition, as one modification, the material off-center amount x _ci
Fix _xci to the solution for the current situation, since a little manipulation of the leveling does not change much. As a result, the number of unknowns can be further reduced, and the target leveling value S ² _dfi can be obtained as a least square solution.

The rolling leveling operation basic amount is calculated from the target value and the current value of the rolling leveling calculated in this way, and is multiplied by a tuning factor to obtain a control output. By passing such a control cycle several times, it is possible to make the difference in tension acting on the rolled material between the rolling mills close to zero, and it is possible to prevent meandering and squeezing of the rolled material. It is to be _noted that an embodiment in which tension rolls are provided on the entrance and exit sides of the tandem rolling mill to measure and use R _dfo and R _dfN is also conceivable. In this case, when σ _dfi = 0, R _dfo and R _dfN are also unknown. Therefore, the balance between the unknowns and the number of equations is the same as in the present embodiment.

As described above, if the measured value of _hdfo is obtained, it should be used for obtaining the current _rolling leveling S ¹ _dfi to improve the reliability of the data. In this case, the present embodiment can be applied to a tandem cold strip mill including two or more rolling mills. FIG. 5 shows the algorithm of the first embodiment.

[0033] (Example 2) in the rolling of the hot strip finishing mill consisting of 3 groups or more rolling mill, rolling load left-right difference P _dfi, looper roll same time data and the finishing of the reaction force left-right difference R _dfi and roll peripheral speed V _i The width distribution of the temperature of the material at the entrance and exit of the rolling mill is measured. Based on the measurement result of the temperature distribution in the width direction of the material, a temperature estimation calculation is performed for each rolling mill roll bite in the finishing mill, and the value of the deformation resistance left-right difference k _dfi = 0 (i = 1 to N) is estimated from this. I do.

At the time when the above data is obtained, the variables ((9)
In the equation, the number of unknowns is 7N + 2. On the other hand, the number of equations becomes 8N-1 including equation (11), and the equations (1) to (8) and (11) are all linearly approximated.
The unknown in (9) can be determined with high accuracy. When the value of the left-right difference σ _dfi of the tension obtained in this way exceeds the allowable value, the reduction of the _rolling reduction is performed. When _{calculating the rolling} leveling operation basic amount ΔS _dfi ,
As described above, the equation system is solved with σ _dfi = 0 (i = 0 to N). At this time, P _dfi and R _dfi are newly unknown.

Therefore, the number of unknowns is 8N, and
One more than the number of equations. At this time, the method of using the measured values of the entrance and exit side plate wedges is defined in the fifth invention of the present application. At this time, the exit side plate wedge can be used when the current solution is obtained, In order to obtain the target value of the draft leveling with the difference being zero, the exit side wedge generally changes due to the operation of the draft leveling, so it is irrational to fix the exit side wedge to the measured value.

Therefore, when determining the target value of the draft leveling, only the entry side plate wedge can be used. By using this, the number of equations and the number of unknowns match, and the above equation system can be solved. Makes it possible to find all solutions.

As another modification, since the material off-center amount x _ci does not change so much even if the leveling is slightly manipulated, the unknowns are further reduced by fixing x _ci to a solution relating to the current state. And the leveling target value S ² _dfi can be obtained as a least square solution.

The rolling leveling operation basic amount is calculated from the target value and the current value of the rolling leveling calculated in this way, and is multiplied by a tuning factor to obtain a control output. By passing such a control cycle several times, it is possible to make the difference in tension acting on the rolled material between the rolling mills close to zero, and it is possible to prevent meandering and squeezing of the rolled material.

An embodiment is also conceivable in which tension rolls are provided on the entrance and exit sides of the finishing mill to measure and use R _dfo and R _dfN . In this case as well, when σ _dfi = 0, R _dfo and R _dfN Must also be unknown, so the balance between the unknowns and the number of equations is the same as in the second embodiment.

As described above, if the measured value of _hdfo is obtained, it should be used for obtaining the current _rolling leveling S ¹ _dfi to improve the reliability of the data. In this case, the present embodiment can be applied to a tandem hot strip mill including two or more rolling mills. FIG. 6 shows an algorithm of the second embodiment.

(Embodiment 3) Using a four-high rolling mill as shown in FIG. 2, calibration of a rolling load measuring device using a work roll bending device is carried out every time work rolls are replaced. After calibrating the above rolling load measuring device, a kiss roll tightening test is performed, and the roll deformation is separated from the data on the relationship between the rolling reduction value and the rolling load measuring device, and the deformation characteristics of the housing and the rolling system are determined. The data is extracted and separately stored in the computer for setting calculation on the working side and the driving side. By calibrating the rolling load measuring device for each work roll change,
It is possible to accurately detect the load acting between the upper and lower work rolls with the rolling load measuring device regardless of the change in the weight of the work rolls and the like. In addition, a kiss roll tightening test is performed every time the reinforcing roll is replaced, and the deformation characteristics of the housing and the rolling system are extracted to detect changes in the deformation characteristics of the elastic contact surface between the reinforcing roll chock and the rolling screw or liner. It is possible to compensate.

FIG. 7 shows a roll bending force and a rolling load measurement in a hot strip mill finishing mill No. 7 stand (four-high rolling mill) in accordance with the calibration method of the rolling load measuring device of the sixth invention of the present application. This is data on the correspondence between devices. In FIG. 7, straight line approximation is performed with the gradient fixed at 1 only for the purpose of zero point adjustment of the rolling load measuring device. From these approximation lines, true loads Q _W and Q _D are calculated by the following equations. . Q _W = P _W +90.5 (21) Q _D = P _D +59.7 (22) On the other hand, FIG. 8 shows data collected by the same rolling mill six months later. From this, the following correction equation is obtained. Q _W = P _W +59.6 (23) Q _D = P _D +131.1 (24) Therefore, when the corrections of the equations (21) to (24) are not performed, the working side and the driving side are used. As for the rolling load difference of (5), there is a change of (90.5-59.7)-(59.6-131.1) = 102.3 tonf in six months. When such a change is left as it is and the difference between the left and right of the rolling load is calculated and used as the measured value of the present invention, a serious disturbance will be added to the control, and accurate zero adjustment of the rolling load is very important. You can see that there is.

[0043]

According to the rolling reduction method for a plate rolling mill of the present invention, the tension difference acting on the rolled material between the rolling mills in the tandem rolling mill row during the steady rolling can be made substantially zero. As a result, there is almost no accident at the time of passing the board, and it is possible to greatly improve the working rate and the yield.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an algorithm of a meandering control method according to the present invention.

FIG. 2 is a side view of a four-high rolling mill, which is a typical plate rolling mill.

Fig. 3 Actual hot strip mill finishing rolling mill No. 6 Stand with no load applied with roll bending force, plotted the corresponding relationship with the output of rolling load measuring device, and graphed the data by linear approximation by least square method is there.

FIG. 4 shows that the same data as in FIG.
3 is a graph approximated by a straight line.

FIG. 5 is a flowchart showing an algorithm according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing an algorithm according to a second embodiment of the present invention.

FIG. 7 is a graph showing the relationship between the output of a rolling load measuring device and a roll bending force applied when no load is applied to a hot strip mill finishing mill No. 7 stand which is the target of Example 2; FIG.

8 is a graph in which similar data is collected by the same rolling mill as in FIG. 7 half a year after the data collection in FIG. 7, and the data is approximated by a straight line having a slope of 1. FIG.

[Explanation of symbols]

1: Rolling load measuring device 2-1, 2-2, 3-1, 3-2: Increment work roll bending device 4-1, 4-2, 5-1, 5-2: Decrease work roll bending device 6-1, 6-2, 7-1, 7-2: Reinforcement roll balance device 8-1, 8-2: Work roll 9-1, 9-2: Reinforcement roll 10-1, 10-2: Work roll chock 11-1, 11-2: Reinforced roll chocks 12: Roll-down device 13: Housing 14: Work roll bending device Operating oil pressure measurement device

Claims (6)

(57) [Claims] 1. A continuous and tandem rolling operation of rolling a metal plate at the same time two or more rolling mill, working side rolling load during rolling, and sampled substantially the same time the driving side pressure rolling load and roll peripheral speed Based on these data, to estimate the left-right difference in tension between each rolling mill acting on the rolled material, with the goal of making the left-right difference in the tension zero,
A meandering control method comprising: obtaining a basic operation amount of a rolling set value left / right difference using an equation system in a steady state of tandem rolling; and controlling a left / right difference of a rolling set value of each rolling mill based on the calculated basic amount. 2. A continuous and tandem cold rolling operation of rolling a metal plate at the same time two or more rolling mill, working side rolling load during rolling, to substantially the same point in time the drive side pressure rolling load and roll peripheral speed Sampling, and further measuring the thickness of the tandem rolling mill row at the entry and exit sides at substantially the same time as the data collection time at two or more points in the sheet width direction, and based on these data, Estimating the left-right difference in tension between rolling mills, with the goal of reducing the left-right difference in tension to zero,
A meandering control method comprising: obtaining a basic operation amount of a rolling set value left / right difference using an equation system in a steady state of tandem rolling; and controlling a left / right difference of a rolling set value of each rolling mill based on the calculated basic amount. 3. A continuous and hot tandem rolling operation of rolling a metal plate at the same time two or more rolling mill, working side rolling load during rolling, to substantially the same point in time the drive side pressure rolling load and roll peripheral speed Sampling, and further, at substantially the same time as the data collection time, the sheet thickness at the entrance and exit of the tandem rolling mill row at two or more points in the sheet width direction, and the temperature of the rolled material at the entrance and / or exit side of the tandem rolling mill row Is measured at two or more points in the sheet width direction, and based on these data, the left-right difference in tension between the rolling mills acting on the rolled material is estimated, and the goal is to reduce the left-right difference in tension to zero. , Using the tandem rolling steady-state equation system to determine the basic amount of operation of the reduction set value left and right difference,
A meandering control method characterized by controlling a left-right difference of a rolling reduction value of each rolling mill based on this. 4. A continuous and tandem cold rolling operation of rolling a metal plate at the same time two or more rolling mill, rolling between the working side rolling load during rolling, drive side pressure rolling load, roll peripheral speed and the rolling mill The material tension was sampled at substantially the same point, and at the same time as the data collection time, the sheet thickness on the tandem rolling mill row entry side was measured at two or more points in the sheet width direction, and rolling was performed based on these data. Estimate the left-right difference of the tension between the rolling mills acting on the material, with the goal of reducing the left-right difference of the tension to zero, using the equation system in the steady state of tandem rolling, the reduction of the set value left-right difference A meandering control method comprising: obtaining a basic operation amount; and controlling a left-right difference of a rolling reduction value of each rolling mill based on the basic operation amount. 5. A continuous and hot tandem rolling operation of rolling a metal plate at the same time two or more rolling mill, rolling between the working side rolling load during rolling, drive side pressure rolling load, roll peripheral speed and the rolling mill The material tension is sampled at substantially the same point, and the sheet thickness at the tandem rolling mill row entry / exit side at substantially the same time as the data collection point is at least two points in the sheet width direction, and the tandem rolling mill row entry side and / or Alternatively, the temperature of the rolled material on the exit side is measured at two or more points in the sheet width direction, and based on these data, the left-right difference in tension between the rolling mills acting on the rolled material is estimated. With the goal of zero
A meandering control method comprising: obtaining a basic operation amount of a rolling set value left / right difference using an equation system in a steady state of tandem rolling; and controlling a left / right difference of a rolling set value of each rolling mill based on the calculated basic amount. 6. A rolling mill constituting a tandem rolling mill row,
It has a hydraulic work roll bending device, and a rolling load measuring device for measuring the load of the drafting device, and in each of the rolling mills, when the roll gap is open at the time of non-rolling, the upper and lower work roll gaps by the work roll bending device. Is applied from the hydraulic pressure detected by the pressure measuring device of the supply oil to the working cylinder of the work roll bending device, the effective sectional area of the working cylinder, and the number of working cylinders. The correspondence between the roll bending force and the output of the rolling load measuring device for measuring the supporting load of the reinforcing roll is analyzed, and the correlation between the two is analyzed separately for the working side and the driving side, and the rolling load measurement is performed. 2. The meandering control method according to claim 1, wherein the method is performed after calibrating the zero point or both the zero point and the sensitivity of the apparatus.