JPH0775815A - Method for controlling meandering of sheet in tandem mill - Google Patents

Abstract

PURPOSE:To provide a method for controlling meandering of a sheet in a tandem mill by which the meandering of the sheet is suppressed-with high responsiveness. CONSTITUTION:The meandering of a material 10 to be rolled is suppressed by estimating the amount of meandering at a rolling stand 12 on the upsream side by using difference load between rolling loads on both sides in the axial direction of roll at the rolling stand 12 on the upstream side and adjusting the differential pressure between bender forces on both sides in the axial direction at the rolling stand 14 on the downstream side corresponding to the estimated amount.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for controlling the meandering of a plate in a tandem rolling mill including a plurality of rolling stands, and more particularly to a method for suppressing the meandering of the plate with high responsiveness.

[0002]

[Background Art] During continuous rolling of a metal sheet in a rolling mill, a difference in rolling reduction between the left and right of the rolled sheet occurs due to a partial hardness difference or leveling error of the rolled sheet, causing a meandering phenomenon in the rolled sheet. Is known to occur.

This meandering phenomenon not only deteriorates the product quality, but in some cases causes plate breakage or unrollability, which significantly impedes productivity. In addition, the meandering phenomenon of the rolled plate material, due to its characteristics, rapidly grows and causes great damage once it occurs, so that the meandering control requires extremely high responsiveness.

Therefore, as a method for controlling the meandering of a plate in a rolling mill, conventionally, as disclosed in Japanese Patent Laid-Open No. 56-11107, the difference between the rolling loads on both sides in the axial direction of the rolling mill is zero. A method of adjusting the bending force on both sides in the roll axial direction so as to achieve the above is proposed.

However, since the conventional meandering control method described in such publications only considers the meandering phenomenon in one rolling stand, the differential pressure adjustment of the bender force is controlled without time delay. However, there is a problem in that it is impossible to cope with the meandering generated in the rolling stand on the upstream side, and a sufficient meandering correction effect cannot be obtained.

Further, in Japanese Patent Laid-Open No. 4-300010, in a tandem rolling mill, a plate wedge change amount of a rolled plate material in an upstream rolling stand is obtained, and from the plate wedge change amount, meandering in a downstream rolling stand is performed. A feedforward type meandering control method is disclosed in which the leveling in a downstream rolling stand is corrected so as to estimate the generation direction and correct the meandering.

However, in the meandering control method disclosed in this publication, the plate wedge change amount of the rolled plate material cannot be directly measured, and the plate wedge change amount must be obtained based on the leveling operation amount. Although it is necessary to find the coefficient of influence on various types of meandering, there is a problem in that it is difficult to accurately calculate the value.

[0008]

The present invention has been made in view of the circumstances as described above, and the problem to be solved is to prevent the meandering of a rolled sheet material in a tandem rolling mill with high responsiveness. It is to provide a method that can be suppressed.

It is another object of the present invention to provide a method capable of performing meandering control with a simple device configuration by using a factor that can be easily measured as a control reference signal.

[0010]

In order to solve such a problem, the feature of the present invention resides in that, in continuous rolling of a plate material by a tandem rolling mill, the rolling load on both sides in the roll axial direction in an upstream rolling stand is increased. Using the differential load, the amount of meandering in the upstream rolling stand is estimated from the differential load, and according to the estimated amount of meandering, the differential pressure of the bending force on both sides in the roll axial direction in the downstream side rolling stand is adjusted to perform rolling. It is to eliminate the meandering of the plate material.

[0011]

EXAMPLES Examples of the present invention will now be described in detail with reference to the drawings in order to clarify the present invention more specifically.

FIG. 1 is a block diagram showing a concrete configuration example of a meandering control device for carrying out the meandering control method according to the present invention. In the figure, reference numeral 10 denotes a rolled plate material, which is fed from the left side to the right side in the figure. The rolling plate material 10 is rolled by an upstream rolling stand 12 and a downstream rolling stand 14. Operations are added one after another.

The rolling stands 12 and 14 are provided with a pair of work rolls 16 and 16 and a pair of backup rolls 18 and 18, respectively. Although not explicitly shown in the drawings, the rolling stands 12 and 14 are each provided with a known electric or hydraulic reduction device.

Further, a load detector 20 such as a load cell for detecting a rolling force on both sides in the axial direction of the roll is attached to the upstream rolling stand 12, and the work roll 1 is also mounted.
A rotation detector 22 for detecting the rotation speed of 6 is attached.

An upstream bender controller 24 and a downstream bender controller 26 are mounted on the upstream rolling stand 12 and the downstream rolling stand 14, respectively, and the bending forces on both sides in the roll axis direction are detected. It has become so. In addition, these vendor control devices 24, 26
As the bender device whose operation is controlled in step 1, any of well-known structures such as a work roll bending system and a backup roll bending system can be adopted.

Further, in such a meandering control device,
In the upstream rolling stand 12, the rolling load, the work roll rotation speed, and the bending force are input to the computing device 28 from the load detector 20, the rotation detector 22, and the upstream vendor control device 24, respectively, and the calculation is performed. In the device 28, the meandering amount generated by rolling of the upstream rolling stand 12 is estimated for each constant length based on these input signals. Further, from the estimated value of the meandering amount, the amount of change in the difference load between the rolling loads on both sides in the roll axial direction in the downstream rolling stand 14 is predicted, and by canceling the difference load, the meandering of the rolled plate material is eliminated. As described above, every time the portion of the rolled plate material corresponding to the estimated meandering amount at the upstream rolling stand 12 reaches just below the downstream rolling stand 14, the downstream rolling stand 14
The differential pressure operation amount of the bending force on both sides in the roll axial direction at
It is adapted to be fed forward to the downstream vendor control device 26.

More specifically, first, FIG. 2 shows a bender controller (2) showing the meandering phenomenon of the rolled sheet material 10 in the upstream rolling stand 12 or the downstream rolling stand 14.
4, 26) including the known block diagram. The meanings of the symbols shown in FIG. 2 are shown below.

K _H : Spring constant of housing / chock, etc. K _F : Spring constant between backup roll and work roll K _f : Work roll flat spring constant l _S : Distance between load points on both sides (roll shaft axial direction) l _R : Roll Barrel distance b: Strip width h: Strip thickness P: Rolling load ∂P / ∂h: Influence coefficient S: Laplace operator v ₁ : Inlet plate speed ζ: Constant determined by rolling conditions G (s): Vendor controller the transfer function [delta] _S: leveling error delta] H: inlet side Weddji amount y _CO: off-center amount y _C: meandering amount d: disturbance .delta.u _B: vendor differential operation amount [delta] P _B: difference load [delta] P resulting from a vendor differential pressure: difference load

Now, assuming that the differential load generated in the upstream rolling stand 12 is δP _i-1 , this δP _i-1 is
It is expressed by the following equation (1).

ΔP _i-1 = 1 / Y {P _i-1 / l _Si-1 · y _ci-1 + δP _Bi-1 + α · δ _Si-1 + β · δH _i-1 } (Equation 1) Where _i-1 : Subscripts representing the upstream rolling stand α, β, Y: Constants determined by the rolling mill and rolling conditions

Further, assuming that there is no initial leveling error, δ _Si-1 = 0, and the wedging side wedge amount: δH is sufficiently smaller than the differential load generated by meandering. The above (Equation 1) formula is the following (Equation 2)
It is expressed as a formula.

ΔP _i-1 = 1 / Y {P _i-1 / l _Si-1 · y _ci-1 + δP _Bi-1 } (Equation 2)

Therefore, the meandering amount: y _ci-1 generated in the upstream rolling stand 12 is estimated by the arithmetic unit 28 shown in FIG.

Y _ci-1 = l _Si-1 / P _i-1 (Y · δP _i-1 −δP _Bi-1 ) (Equation 3)

Next, the amount of change in the differential load δP _i in the downstream rolling stand 14 is predicted. Now, in the differential load in the downstream rolling stand 14, except for the output from the downstream bender controller 26, if the component affecting the differential load is the disturbance: d _i , the change amount of the differential load is (Number 4)
It is expressed as an equation.

ΔP _i = G _i (s) · δu _Bi + d _i (Equation 4) where _i is a subscript indicating a downstream rolling stand

The outside of the downstream rolling stand 14
Ran: d_iAs the leveling error: δ_siInfluence, entry side
Wedge amount: δH_iAnd meandering: y_ciCaused by
Difference load is considered, but leveling error: δ_si= 0
If so, the amount of wedge on the entry side: δH _iDifferential load generated by
Meandering: y_ciSufficiently small compared to the differential load generated by
Therefore, the difference load generated by the meandering is disturbed: d_iWhen
If you look at it d_iIs expressed as in the following (Equation 5).
Be done.

D _i = P _i / l _Si · y _ci ( _Equation 5) where y _{ci is} the meandering amount just below the downstream rolling stand (the meandering amount generated at the upstream rolling stand: y _ci-1 , Tracking value right under the rolling mill on the downstream side)

Therefore, in order to make the amount of change of the differential load: δP _i in the downstream rolling stand 14 to be zero, the operation amount of the differential pressure difference of the vendor: δu which cancels the disturbance: d _i expressed by the equation (5). _It is good to give _Bi . That is, now, if the response delay of the downstream vendor control device 26 is approximated as a first-order delay, the equation (4) is changed to the following equation (6).
expressed.

ΔP _i = {K _i / (T _i s + 1)} · δu _Bi + d _i (Equation 6) where K _i : Vendor controller gain T _i : Vendor controller time constant s: Laplace operator

Therefore, the bender differential pressure operation amount δu _Bi that cancels the disturbance: d _i that causes the differential load may be any that satisfies the following equation (7).

{K _i / (T _i s + 1)} · δu _Bi + d _i = 0 (Equation 7)

Therefore, according to the equations (5) and (7), in order to cancel the differential load (disturbance: d _i ) generated by the meandering generated by the upstream rolling stand 12, the downstream rolling stand 14 is canceled. Vendor differential pressure operation amount to be added in δu _Bi is expressed by the following equation (Equation 8).

Δu _Bi = −d _i / {K _i / (T _i s + 1)} = − m / K _i · y _ci −mT _i / K _i · ∂y _ci / ∂t (Equation 8) , M = P _i / l _Si ∂y _ci / ∂t: differential value of meandering amount just below the downstream rolling stand 14.

In the equation (8), ∂y _ci / ∂t
The calculation of (differentiation of the meandering amount tracking value) is specifically performed by using, for example, the following Stirling interpolation formula.

That is, when n is a positive odd number, and the m-th derivative of the n-th point is fn ^(m) (t), such fn ^(m)
(t) is expressed as in the following (Equation 9).

[0037]

[Equation 9]

Therefore, as shown in FIG. 3, the calculated values of the amount of meandering corresponding to the upstream side portion of the rolled plate 10 are, in order, Δy _C2 , Δy _C1 , Δy _C0 and Δy _C-1. , Δy
_{If it is C-2,} it can be expressed as the following equations, respectively. Δy _c (t + 2δ) = Δy _C2 Δy _c (t + δ) = Δy _C1 Δy _c (t) = Δy _C0 Δy _c (t−δ) = Δy _C-1 Δy _c (t-2δ) = Δy _C-2

Therefore, in the above equation (9), for example, if the five-point formula (n = 5) is used, then the ∂y _Ci / ∂t is
It is expressed as in the following (Equation 10).

[0040] _{∂y Ci / ∂t = 1 / δ} {- 1/12 · Δy C2 + 2/3 · Δy C1 - 2/3 · Δy C1 + 1/12 · Δy C2} ··· (Equation 10)

Therefore, the above equation (8) and equation (10)
By using the formula to give the operation amount of the vendor differential pressure in the downstream rolling stand 14, the downstream vendor control device 26
Response delay is compensated and the downstream rolling stand 1
The difference load change at 4 can be canceled and the meandering can be suppressed.

That is, in the above method, based on the estimated meandering amount in the upstream rolling stand 12,
When such a meandering location reaches the downstream rolling stand 14, the bender differential pressure in the downstream rolling stand 14 is manipulated to suppress the meandering of the rolled plate material 10. Therefore, the meandering with high responsiveness is achieved. Can be suppressed.

Moreover, in this method, since the differential load in the upstream rolling stand 12 is used as the reference signal for control, the reference signal can be easily detected by the load detector 20 such as a load cell. Therefore, the simplification of the device configuration can be advantageously achieved.

Incidentally, in order to confirm the effect of the plate meandering control method in the tandem rolling mill according to the present invention, a simulation was carried out by using the model as described above to investigate the meandering suppressing effect. The results are shown in FIG. 4 as (b) together with the comparative example (a) when the control is not performed. The simulation conditions are shown below.

K _H = 1000 tf / mm K _F = 1500 tf / mm K _f = 2000 tf / mm l _S = 3000 mm l _R = 2300 mm b = 1400 mm h = 8 mm P = 700 tf ∂P / ∂h = -200 tf / mm v ₁ = 50mm / min ζ = 1 K B = 1 T B = 100ms

From this simulation result, it is clear that the meandering control method according to the present invention can effectively suppress the meandering in the rolled sheet material.

The embodiments of the present invention have been described in detail above, but these are literal examples, and the present invention should not be construed as being limited to such specific examples.

For example, in the above-mentioned embodiment, the model provided with the two rolling stands 12 and 14 is shown as a concrete configuration example of the meandering control device for carrying out the meandering control method according to the present invention. It is needless to say that the present invention can be advantageously applied to the meandering control of a plate in a tandem rolling mill equipped with one or more rolling stands.

Further, in addition to the feedforward type meandering control according to the present invention, for each single rolling stand,
Conventionally known single feedback type meander control,
It is also possible to apply independently.

Although not listed one by one, the present invention
Based on the knowledge of those skilled in the art, it can be implemented in various modified, modified, and improved modes, and
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0051]

According to the method of the present invention, when the meandering occurrence site in the upstream rolling stand reaches the downstream rolling stand, the bender differential pressure in the downstream rolling stand is controlled so as to suppress the meandering. Therefore, the meandering can be suppressed with high responsiveness.

Moreover, in the method of the present invention, since the differential load in the upstream rolling stand, which can be easily detected by the load cell or the like, is used as the reference signal for the meandering control, simplification of the apparatus configuration is also advantageous. Can be aimed at.

[Brief description of drawings]

FIG. 1 is a block diagram showing a specific configuration example of a meandering control device for carrying out a meandering control method according to the present invention.

FIG. 2 is a block diagram showing a meandering phenomenon of a rolled plate material in a rolling stand.

FIG. 3 is an explanatory diagram for explaining a method of calculating a derivative of a meandering amount tracking value using a Stirling interpolation formula.

FIG. 4 is a graph showing a simulation result of the meandering control method according to the present invention together with a comparative example.

[Explanation of symbols]

 10 Rolled Plate Material 12 Upstream Rolling Stand 14 Downstream Rolling Stand 16 Work Roll 18 Backup Roll 24 Upstream Vendor Control Device 26 Downstream Vendor Control Device

Claims (1)

[Claims] 1. When continuously rolling a plate material by a tandem rolling mill, a differential load between rolling loads on both sides in the roll axial direction of an upstream rolling stand is used, and the amount of meandering in the upstream rolling stand is estimated from the differential load. According to the estimated amount of meandering, a meandering control method for a plate in a tandem rolling mill is characterized in that the meandering of the rolled plate material is eliminated by adjusting the differential pressure of the bending force on both sides in the roll axial direction in the downstream rolling stand. .