JP2956934B2 - Rolling control method in hot strip finishing mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling rolling in a hot strip finishing mill, and more particularly, to a method in which a strip profile and a thickness in the width direction at the exit side of a final stand can be accurately hit a target value. The present invention relates to a rolling control method in a hot strip finishing mill.

[0002]

2. Description of the Related Art In a hot strip finishing mill, a control for adjusting a thickness distribution (plate profile) in a width direction and a flatness of a plate together with a plate thickness is performed.

[0003] In controlling the plate profile (plate crown), a crown control device installed in each rolling stand constituting the finishing mill is controlled so that the plate profile on the exit side of the final stand matches the target value. .

[0004] Therefore, usually, a plate profile meter for actually measuring the plate profile is installed on the exit side of the final stand of the finishing mill, and the result of measurement by the plate profile meter is used to obtain a plate of the product rolled at the final stand. The control deviation for the next rolled material is reduced by managing the profile and learning the model for controlling the plate profile.

In the above-mentioned plate profile control, for example, a control model formula represented by the following formula (1) can be used. In the case of a tandem rolling mill having N stands, each stand corresponds to formula (1). By formulating the following formulas and combining a total of N formulas, the plate profile on the exit side of the final stand can be obtained.

C _ri = α _i · C _rmi + β _i · C _ri-1 (1)

In the above formula (1), C _ri is a plate profile on the exit side of the ith rolling stand counted from the upstream side,
_rmi is the so-called mechanical crown of the stand, C
_ri-1 is the i _{-1st, that} is, the plate profile on the exit side of the former stand, α _i is the transfer rate of the mechanical crown,
β _i is a genetic coefficient for the plate profile of the preceding stand. Hereinafter, these will be described in order.

The mechanical crown C _rmi of the above formula (1)
Is the mechanical change in the widthwise distribution of roll spacing caused by roll deflection, roll thermal expansion or roll wear due to rolling load. _Assuming that the crown caused by the roll deflection due to the rolling load is C _mpi , the crown caused by the thermal expansion of the roll is C _mRhi, and the crown caused by the roll wear is C _mRwi , the mechanical crown C _rmi is expressed by the following equation (2). It is.

C _rmi = C _mpi + C _mRhi + C _mRwi (2)

In the above equation (2), the crown C _mpi caused by the roll deflection is determined based on the load distribution in the width direction, based on (i) the deflection of the work roll and the backup roll (including the change due to the output of the crown control device), and (ii). considering initial crown like rolls, it is given by the function f ₁ represented by the following equation (3). Here, in this equation, P is the rolling load, b is the material width, and x is the output of the crown control device.

C _mpi = f ₁ (P, b, x) (3)

The crown (heat crown) _CmRhi due to the thermal expansion of the roll is obtained by _formulating the change of the roll crown accompanying the progress of rolling and cooling after rolling by a method such as approximation of a first-order response, and calculating each time constant and proportionality. Constants and the like can be determined by regression from experimental data.

When the above-mentioned heat crown is determined, the surface condition of the roll changes as black scale is formed or falls off as the rolling progresses in, for example, a hot strip finishing mill, and the friction coefficient and the heat transfer coefficient are changed. When the heat input from the strip to the roll changes due to the change in the heat input, this causes a heat crown estimation error, but this change in the heat input cannot be measured.

Further, the crown C _mRwi caused by the roll wear is _used.
Is expressed by the following equation (4) including the function f ₂ . However,
Cf is the wear coefficient, L is the pressure extension, and D is the roll diameter.

C _mRwi = Cf · f ₂ (P, L, b, D) (4)

In the above equation (4), Cf is determined by regression of the rolling result. Since the degree of wear of the roll changes depending on the material characteristics and the surface condition of the roll, this estimates the crown _CmRwi due to the roll wear. Error factors.

In the above equation (1), the transfer rate α _i is given by a function f ₃ represented by the following equation (5).

Α _i = f ₃ (h, Ld, Kch, ξ) (5)

Here, h is the exit side plate thickness, Ld is the contact arc length,
Kch is the plate width, the contact arc length, the regression coefficient changes by deformation resistance, etc., xi] is the shape change factor given by the function f ₄ that is expressed by the following equation (6).

Ξ = f ₄ (D, h, b) (6)

The genetic coefficient β _i is given by a function f ₅ expressed by the following equation (7). H is the thickness of the entry side plate.

Β _i = f ₅ (Kch, Ld, ξ, h, H) (7)

The transfer rate α _i of the above formula (5) and the above (7)
Since the genetic coefficient β _i in the equation uses the regression coefficient Kch and the shape change coefficient 同 じ く similarly obtained regressively as variables, α _i and β _i are each determined recursively based on the experimental results. .

Hereinafter, a conventional general plate profile control method using the above-described formula (1) will be described with reference to a specific example of a hot strip finishing mill of seven stands including a first stand F1 to a seventh stand F7. It will be described as.

First, assuming a pass (threading) schedule for performing finish rolling, the rolling load on each stand is predicted and calculated, and the exit plate thickness of the finishing mill, ie, the exit plate thickness h ₇ of the seventh stand. And the target plate crown C of the seventh stand
_r7 ^Aim Final target ratio crown R _c7 ^Aim (= C
_r7 ^Aim / h ₇ ), and using this, the target crown C _ri on the exit side of each stand from the above pass schedule.
To determine the ^{_{Aim (= R c7 Aim × h}} i).

Next, based on the above equation (1), a target mechanical crown C _rmi ^Aim for achieving the target plate crown C _ri ^Aim for each stand is determined, and a crown control device for achieving the target mechanical crown is obtained. Determine the output of

[0027] Thereafter, the actual plate rolling, the plate crown C _r7 out of the final stand F7 measured by a plate profile meter is installed in the outlet side the stand, the actual delivery side crown C results from _r7 ratio crown R _c7 (= _Cr7 / h
₇ ) Ask for.

Next, assuming that the ratio crown on the exit side of each stand is equal to the actual ratio crown _Rc7 on the exit side of the seventh stand F7, the actual rolling load on each stand and the actual ratio crown _Rc7 are used to determine each stand. obtaining an error S _i from the equation (1) in the. That is, the _output side crown C _ri of the ith stand is _calculated as R _c7 × h _i , and the error S _i that satisfies the following equation (8) is determined. The mechanical crown _Crmi is calculated using the actual rolling load.

C _ri = α _i · C _rmi + β _i · C _ri-1 + S _i (8)

As described above, for each stand (8)
After obtaining the equation, learning for using the equation (8) for setting the crown of the next material is performed. Also, determine the appropriate mechanical crown C _mri for matching the side plate crown out of each stand using the error S _i to the target value, to change the crown control unit output for each stand to match the mechanical crown And perform feedback control.

As described above in detail with reference to an example, in the conventional hot strip finishing mill, the plate profile control device of each stand is controlled based on the measurement result by the plate profile meter installed on the exit side of the final stand. A way to control was taken.

As a technique substantially the same as that described above, for example, Japanese Patent Application Laid-Open No. Sho 60-223605 discloses that in order to simultaneously control a sheet crown and a sheet shape to desired values, one of a finishing stand and a final stand is used. A method is disclosed in which both a plate crown and a plate shape are rolled as desired by controlling a plate profile and a plate shape of a final stand using a plate profile control device of two stands of an upstream stand. However, in this method, the last stand and one more than the last stand
There was a risk that the shape between the stands upstream and downstream would be disturbed, which would hinder operation.

Therefore, in order to prevent the shape from being disturbed by the stand on the way, a method of controlling the stand from a more upstream stand is disclosed in Japanese Patent Application Laid-Open Nos. 60-127003 and 63-1990.
99, Japanese Patent Application Laid-Open No. 1-266909. In general, in the hot rolling, since the thickness of the plate is small and the crown control ability is small in the subsequent stand, control before the middle stage of the finishing mill is effective. Accordingly, in this regard, the methods disclosed in these publications are effective control methods since control is performed retroactively to the upstream stand.

Further, Japanese Patent Application Laid-Open Nos. 62-168608 and
No. 37908 discloses a method of installing and controlling a plate profile meter on the entrance side of a tandem rolling mill.

Further, Japanese Patent Laid-Open No. 59-39410 discloses that a plate profile is measured by a front stand, and the plate profile is controlled by a front stand based on the measured value.
A method is disclosed in which the shape is roughly controlled by a rear stand, the flatness is measured on the exit side of the final stand, and the flatness is precisely controlled by the rear stand based on the measured value.

[0036]

However, according to the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-127003,
Since the transfer time between the stands is long, the control system has a large dead time, and there is a problem that only control with poor response can be performed.

According to the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Sho 62-168608, in the hot rolling, the metal flow in the plate width direction is large in the former stand, and the variation of the plate profile on the entry side of the tandem rolling mill is reduced. Since the influence is small, there is a problem that there is almost no effect of controlling the plate profile.

Further, in the method disclosed in Japanese Patent Application Laid-Open No. Sho 59-39410, the plate profile is controlled by feedback control in the front stand after the front end passes through the front stand. There is a problem that control is not effective.

In addition, none of the methods disclosed in the above publications simultaneously control the thickness in the width direction.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to reduce the width-direction plate thickness of the final stand exit side together with the plate profile of the final stand exit side without causing a shape defect in the strip. An object of the present invention is to provide a rolling control method in a hot-strip finishing mill with high responsiveness, which can accurately hit a target value from a tip end.

[0041]

[0042]

The present invention SUMMARY OF THE INVENTION The rolling stand several are in rolling control method in hot strip finish rolling mill formed by continuously provided, passing between the stand plate profile meter installed between stands Before the strip tip passes through the final stand, the strip profile at the exit of the final stand is measured based on the deviation between the actual plate profile measured by the plate profile meter and the target plate profile at the same actual measurement position. Perform plate profile control on the rolling stand on the downstream side between the plate profile meter installation stand to reduce the error with the target value of,
Based on the deviation between the measured width direction thickness measured by the plate profile meter and the target width direction thickness at the same measurement position, an error between the target value of the width direction thickness on the exit side of the final stand is reduced. After the rolling position of the rolling stand on the downstream side is corrected, the strip profile at the exit side of the final stand is predicted based on the measured plate profile after the end of the strip has passed through the final stand, and the predicted plate profile and the final stand exit are estimated. The plate profile control is performed on the rolling stand on the downstream side between the plate profile meter installation stands so as to reduce the error with the target plate profile on the side, and based on the measured width direction thickness measured by the plate profile meter. Predict the width in the width direction at the exit side of the final stand, and calculate the estimated thickness in the width direction and the exit side of the final stand. By modifying the pressing position of the rolling stands of the downstream so as to reduce the error in the target width direction thickness Prefecture of definitive, is obtained by achieving a pre-Symbol challenges.

For convenience, here, for reference, in a rolling control method in a hot strip finishing mill in which a plurality of rolling stands are connected in series, a plate profile meter installed between the stands passes between the stands. The plate profile of the strip is measured, and based on the measured plate profile, the plate profile control is performed on the rolling stands on the upstream and downstream sides between the plate profile meter installation stands, and the measured width direction measured by the plate profile meter is performed. The above-mentioned problem is also solved by correcting the rolling positions of the rolling stands on the upstream and downstream sides between the stand for installing the same profile meter based on the sheet thickness.
Possible inventions (hereinafter referred to as reference inventions) will be introduced .
Can be.

First, a preferred installation position of a plate profile meter installed between stands in the present invention will be described. However, the present invention is not limited to the installation of the plate profile meter at this position.

As described above, in the subsequent stage of the hot strip finishing mill, it is extremely difficult to significantly change the plate profile because a plate shape defect occurs in the product.

In general, in order to perform rolling without disturbing the shape of the plate, it is necessary to perform the rolling while keeping the ratio crown of the plate constant.

As a result of various studies on the rolling phenomenon, the present inventors have found that if a certain thickness is present, even if residual stress distributed in the width direction occurs due to deviation from the state where the ratio crown is constant, the shape of the plate can be reduced. It has been found that rolling can be performed without causing turbulence.

FIG. 1 is a diagram specifically showing an example of the relationship between the sheet thickness and the ratio crown change limit without disturbing the plate shape, which is the basis of the above knowledge. The limit increases when the plate thickness is 2 mm or more.
It can be seen that the saturation gradually increases when the distance exceeds mm.

Here, the ratio crown change limit is defined as i-th
The ratio crown change rate ΔR _ci (= R) which is the difference between the ratio crown R _{ci -1 (} value obtained by dividing the crown by the thickness of the central portion) on the entrance side of the stand and the ratio crown R _ci on the exit side of the stand.
_ci-1 −R _ci ).

FIG. 1 shows the experimental results. The reason why the ratio crown change limit is saturated when the plate thickness exceeds 4 mm as described above is presumed as follows. In a region where the plate thickness is large, buckling due to internal stress is unlikely to occur even when the ratio crown is changed, but it is considered that the presence of the internal stress makes it difficult to change the ratio crown.

For example, when the ratio crown is changed in the direction in which the ratio crown decreases, compression acts on the center in the width direction and tension acts on the end in the width direction. As a result, the rolling load increases at the center in the width direction, and conversely, the rolling load decreases at the edge. Since this tendency becomes stronger as the sheet thickness increases, it is considered that an attempt to change the ratio crown results in a change in the distribution of the rolling load in the width direction, which limits the margin of change in the ratio crown.

Also, there is, of course, a limitation on the crown changeable amount of the crown control device. This is also considered to be a factor limiting the amount of change in the ratio crown on the thicker side.

Further, the genetic coefficient β in the equation (1) shown in FIG.
_From an example of the relationship between _i and the plate thickness, if the plate thickness is large, β _i is small, but since the disturbance due to subsequent rolling is large, the plate profile changes in rolling to the final stand exit side, and as a result, the final Because the ability to control the plate profile of the product is reduced, even if the plate profile is measured at a stage where the thickness is excessively large, the measured value cannot be effectively used for control.

Therefore, the stand between the stands where the plate profile meter is installed is preferably a stand where the plate thickness of the passing strip is 2 mm or more and the plate shape is not disturbed even if the ratio crown is changed to some extent, preferably 2 mm or more. It is particularly preferable that the distance between stands is 4 mm or less.

Here, based on the deviation between the measured plate profile obtained between the plate profile meter installation stands and the target plate profile at the same measured position, the error between the plate profile at the exit of the final stand and its target value is determined. The plate profile control is performed on the rolling stand on the downstream side between the plate profile meter installation stands so as to reduce the plate width, and based on the deviation between the measured width direction plate thickness and the target width direction plate thickness at the actual measurement position, the final Consider a case in which feed-forward control of a sheet profile and a sheet thickness in the width direction is performed, in which the rolling position of the rolling stand on the downstream side is similarly corrected so as to reduce an error between the sheet thickness in the stand side and the target value in the width direction. Between the plate profile meter installation stand, for example, the plate profile and the tip of the strip Even if deviation occurs between the respective target values in the direction thickness, the plate profile and the width direction thickness from said distal portion at the final stand delivery side can be hit in the product target value.

In the feed forward control of the plate profile, the downstream rolling stand is controlled based on the deviation between the measured plate profile and a previously determined target plate profile. The actual ratio crown is obtained, and the ratio crown can be changed, for example, within the allowable range shown in FIG. 1 according to the deviation between the actual ratio crown and the target ratio crown. By changing the ratio crown within the above-mentioned allowable range for the rolling stand, it is possible to hit the plate profile on the exit side of the final stand to the target value without causing the plate shape to be disturbed. The amount of change of the ratio crown given to the downstream stand at that time can be obtained as follows.

For example, the plate crown on the exit side of the fourth stand F4 is measured, and the measured plate crown _Cr4 and the same stand F4 are measured.
The deviation ΔC _r4 from the exit-side target plate crown C _r4 ^Aim is set to the fifth
The case where the correction is performed by the stand F5 will be described. The sheet crown change amount ΔC _r5 on the exit side of the fifth stand F5 can be obtained by the following equation (9).

ΔC _r5 = β ₅ ΔC _r4 (9) where ΔC _r4 = C _r4 −C _r4 ^Aim

If the shape is disturbed when the plate crown is changed and controlled only by the fifth stand F5, the fifth stand F5 and the sixth stand F6 or the fifth
It is also possible to control the plurality of stands from the seventh stand F5 to the seventh stand F7 by sharing the plate crown change amount.
Further, the control can be performed only by the sixth stand F6 and only by the seventh stand F7.

In the feedforward control of the width in the width direction, the rolling position of the downstream stand is corrected so as to reduce the error between the measured width in the width direction at the end of the final stand and the target width in the width direction. , The amount of reduction ΔS
Can be obtained using the following equation (10).

ΔS = (G / M) · (∂P / ∂H) · ΔH (10)

Where G is the control gain, M is the mill constant,
P is the rolling load, H is the entry side plate thickness, and ΔH is the entry side plate thickness deviation (actual measurement value−target value).

The correction amount obtained by the above equation (10) is a case where correction is performed in one stand immediately after the measurement. When the correction amount is large, the correction amount is shared among a plurality of stands in consideration of mass flow balance and shape. May be controlled.

However, in the above-described method for controlling the plate profile and the plate thickness in the width direction, there is an effect of only canceling the disturbance generated up to the fourth stand F4, but the disturbance generated after the fifth stand F5 is completely considered. Absent.

For convenience, a reference example will be described here.
After the end of the strip passes through the final stand, predict the plate profile at the final stand exit side based on the actually measured plate profile obtained by actually measuring with the plate profile meter between the plate profile meter installation stands, and predicting the same. In order to reduce the error between the plate profile and the target plate profile on the exit side of the final stand, the plate profile control is performed on the rolling stand on the downstream side between the stand where the plate profile meter is installed, and the sheet profile is measured by the plate profile meter. Predict the width in the width direction on the exit side of the final stand based on the actually measured width in the width direction, and reduce the error between the predicted width thickness and the target width in the final stand exit side. when correcting the pressing position of the rolling stands of the downstream
In the first stand, the sheet thickness in the width direction together with the sheet profile can be hit to the target value on the exit side of the final stand.

[0066] As in this reference example, rather than the final stand delivery side, causes the plate profile in the final stand outlet side based on the measured sheet profile of the leaf profile meter installed between the stand coincide with a target value, the plate If feedforward control is performed to match the width in the width direction on the exit side of the final stand to the target value based on the actual thickness in the width direction measured by the profile meter, appropriate selection should be made between the stands where the above-mentioned profile meters are installed. By this, without causing disturbance in the plate shape,
On the exit side of the final stand, the thickness in the width direction and the thickness in the width direction can be hit with the target value with high accuracy, and the control of the thickness and the thickness in the width direction can be controlled with high response.

In the feed forward control of the plate profile in this case, the equations (1) to (7) can be used to obtain the predicted plate profile on the exit side of the final stand based on the actually measured plate profile.

Further, in order to reduce the error between the obtained predicted plate profile and the target plate profile, the amount of change of the plate crown applied to the downstream rolling stand can be obtained as follows.

Similarly, the case of measuring the sheet crown on the exit side of the fourth stand F4 will be described.
In order to predict and calculate the plate crown on the exit side of the seventh stand F7 from the actually measured plate crown _Cr4 on the fourth exit side, the above-described (1) to (7)
Use the formula.

[0070] As a seventh stand F7 delivery side of the strip crown C _r7 predicted becomes the target strip crown C _r7 ^Aim of the stand delivery side, for example of the fifth stand F5 delivery side strip crown of the following formula (11) _Is changed by the change amount ΔC _r5 determined by

ΔC _r5 = (1 / β ₆ β ₇ ) ΔC _r7 (11) where ΔC _r7 = C _r7 −C _r7 ^Aim

In the case where the shape is disturbed by controlling only the fifth stand F5 as described above, when the downstream stand is changed using the deviation between the measured plate crown of the fourth stand F4 and the target plate crown. In the same manner as described above, control may be performed by assigning to a plurality of stands.

According to the first aspect of the present invention, before the leading end of the strip passes through the final stand, the final stand exit is determined based on the deviation between the measured plate profile measured by the plate profile meter and the target plate profile at the same measured position. The plate profile control is performed on the rolling stand on the downstream side between the plate profile meter installation stands so as to reduce the error with the target value of the plate profile on the side, and the measured thickness in the width direction measured by the plate profile meter. Based on the deviation from the target width direction plate thickness at the same measurement position, the rolling position of the downstream rolling stand is corrected so as to reduce the error with the target value of the width direction plate thickness at the final stand exit side, After the end of the strip passes through the final stand, the final stand is A plate profile control is performed on a rolling stand on the downstream side between the plate profile meter installation stands so as to predict a plate profile at the outlet side and reduce an error between the predicted plate profile and a target plate profile at the final stand outlet side. Then, the width direction thickness at the exit side of the final stand is predicted based on the measured width direction thickness measured by the plate profile meter, and an error between the predicted width direction thickness and the target width direction thickness at the final stand exit side. Since the rolling position of the downstream rolling stand is corrected so as to reduce the pressure, the feed forward control of the plate profile is performed based on the above-mentioned equation (9) before the leading end of the strip passes through the final stand. The method is performed, and after the end of the strip has passed through the final stand, based on the above equation (11). His method is carried out.

Here, the difference between the control method based on equation (9) and the control method based on equation (11) will be described.

The method according to the equation (9) uses the fourth stand F4
This is a method for eliminating an error that occurs after the fifth stand F5 due to an error (deviation) ΔC _r4 = C _r4 −C _r4 ^Aim detected on the exit side. At the time of controlling the plate profile at the leading end of the strip, since there is no actual data after the fifth stand F5 (because the strip is not engaged), the seventh stand F7 is not used.
This method is used because it is not meaningful to predict the sheet crown up to.

On the other hand, the method based on the equation (11) predicts the _strip crown C _r7 on the exit side of the seventh stand based on the actually measured _strip crown C _r4 on the exit side of the fourth stand. In this prediction, unlike the prediction at the time of setting calculation, _Cr7 is predicted using the actual value during rolling. That is, in the method according to the equation (9),
In contrast to the control that only cancels the disturbance that occurs up to the fourth stand F4, the method based on the equation (11) predicts _Cr7 using the actual rolling performance, and thus the influence of the disturbance that occurs after the fifth stand F5. Is also considered.

[0077] That is, in the above invention of claim 1, the deviation between the target strip crown that occurs between the plate profile meter position stand (hereinafter referred to also as between certain stand), and, both disturbances that occur after between specific stand The deviation from the target position crown on the exit side of the final stand caused by the above is predicted, and the stand on the downstream side between the specific stands is controlled so as to reduce the deviation from the target plate crown on the exit side of the final stand. .

The disturbance mentioned here includes rolling load, deformation resistance and the like. In the present invention, the disturbance after the specific stand is obtained from the actual rolling results after the end of the strip passes through the final stand. However, since there is no means for predicting the disturbance before the end of the strip passes through the final stand, even if the crown change amount of the stand on the downstream side between the specific stands is obtained by the equation (9), it is obtained by the equation (11) However, the crown change amounts are the same. Therefore, the invention of claim 2 employs a method of calculating the crown change amount by the equation (9) before the strip passes the final stand.

Further, in the feed-forward control of the width in the width direction in this case, the estimated width in the width direction on the exit side of the final stand is obtained based on the actually measured width in the width direction.

In order to reduce the error between the obtained predicted width direction thickness and the target width direction thickness, the rolling position correction amount given to the downstream rolling stand is, for example, the following (12) ) Can be expressed as

Now, the predicted thickness of the exit of the seventh stand F7 is
h _7, if the target thickness value of the same stand F7 delivery side and h ₇ ^Aim, the reduction correction amount [Delta] S ₅ of the fifth stand F5, can be expressed by the following equation (12). Note that Δh ₇ = h ₇
− H ₇ ^Aim .

ΔS ₅ = {(M ₅ + Q ₅ ) / M ₅ } · {(M ₆ + Q ₆ ) / (∂P ₆ / ∂H)} × ｛(M ₇ + Q ₇ ) / (∂P ₇ / ∂ _{H)} · Δ h 7 ...} (12)

In the reference invention, the plate profile control is performed on the rolling stands on the upstream and downstream sides between the stand for setting the plate profile meter based on the measured plate profile, and based on the measured thickness in the width direction. Similarly, when correcting the rolling position of the upstream and downstream rolling stands, the above-described feedback control and feedforward control of the plate profile and the width direction plate thickness are performed at the same time. Even if there is a deviation between the measured value and the target value in the plate profile and the width direction thickness, both of them can always hit the target value from the leading end of the strip on the exit side of the final stand.

More specifically, the feedback control will be described. The deviation between the actually measured plate profile obtained between the stands on which the plate profile meter is installed and the target plate profile obtained in advance between the stands is determined, and the deviation is reduced. In order to reduce the deviation between the measured width direction thickness and the target width direction thickness, rolling profile control is performed on the rolling stand on the upstream side of the stand between the stands. Since the position is corrected, feedback control is performed on the stand on the upstream side of the stand between the plate profile meter installation stands, so that the plate profile and the width direction plate thickness are both set to the target values between the plate profile meter installation stands. Can be matched.

In the feedback control of the plate profile, the plate profile meter measures the plate profile of the strip passing between stands at the time of passing, determines the target ratio crown from the target plate profile of the product, and determines the target ratio crown. In order to match the actual ratio crown obtained from the profile measurement results between the stands, for example, the control change amount is distributed to each stand at a fixed ratio to control the profile of the rolling stand upstream from the plate profile meter installation position. This can be performed by operating a device (a roll bender or a roll crossing angle adjusting device).

By performing this feedback control, for example, as a result of measuring the leading end of the strip with the above-mentioned plate profile meter, there is a case where a deviation exists between the actually measured plate profile and the target plate profile at that position. After that point, the strip can always be controlled to the target plate profile between the stands at the plate profile measurement position, and thereafter, by rolling at a constant ratio crown, the product on the exit side of the finishing mill can be obtained. Can accurately hit the plate profile with the target value.

The feedback control of the thickness in the width direction is performed as follows.
For example, based on the plate thickness at a specific position in the width direction actually measured by the plate profile meter, the upstream side to reduce the deviation between the plate thickness at the specific position in the width direction between the plate profile meter installation stands and its target value. This can be done by correcting the rolling position of the stand against the stand.

As a method of correcting the rolling position, for example, a method of sequentially integrating the difference between the measured value and the target value of the sheet thickness at the specific position in the width direction and adding the result to the target value of the AGC of the preceding stand (monitor method). Can be adopted.

[0089]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a schematic diagram showing a part of a hot strip finishing mill applied to a rolling control method according to an embodiment of the present invention.

The finishing mill used in the present embodiment is a continuous rolling mill consisting of a first stand F1 to a seventh stand F7, all of which are shown in FIG.
The fourth to seventh stands F7 are shown.

In the above continuous rolling mill, each stand is provided with a plate profile control device 10, a load cell 12, and a plate thickness control device 14. In addition, as for these, the fourth stand F4 to the seventh stand F7 are illustrated by adding the suffixes A to D to the above reference numerals, respectively, but the first stand F1 to the third stand F3 which are omitted are also shown. It has the same configuration.

The fourth stand F4 to the seventh stand F7
The plate profile control arithmetic device 16 is connected to the plate profile control devices 10A to 10D, and the arithmetic device 16
Thus, a control signal for controlling the plate profile is input to each of these plate profile control devices 10A to 10D.

A thickness control arithmetic unit 18 is connected to the thickness control units 14A to 14D.
Thus, a control signal for controlling the thickness is input to each of the thickness control devices 14A to 14D.

A fourth stand F4 and a fifth stand F5
Between the fourth stands, between the fifth stands F5 and the sixth stand F6, between the fifth stands, and the final seventh.
On the exit side of the stand F7, there is a first plate profile meter 2
0A, a second plate profile meter 20B, and a third plate profile meter 20C.
The actually measured plate profile measured by the third to third plate profile meters 20A to 20C is input to the plate profile control arithmetic unit 16. Also, the fifth
A roll profile meter 22 is installed on the work roll of the stand F5.
The measured roll profile measured in 2 is similarly input to the plate profile control arithmetic unit 16.

The sixth stand F6 and the seventh stand F7
The first thickness gauge 24A and the second thickness gauge 24B are respectively installed between the sixth stand and the exit side of the seventh stand F7, and the actual measurement plate measured by the thickness gauges 24A and 24B is provided. The thickness is input to the thickness control arithmetic unit 18.

Further, a flatness meter 26 is provided between each of the fourth, fifth and sixth stands so that the flatness of the strip passing between these stands can be measured. .

Next, the operation of the present embodiment will be described for the case where the above (1) is used as a plate profile control type.

In this embodiment, the fourth stand F4
The pass schedule is set so that the strip passing between the first and fifth stands F5 (between the fourth stands), that is, the strip rolled in the fourth stand F4 has a thickness of 4 mm or less and 2 mm or more.

In the present embodiment, the strip (rolled material) S rolled at the first to fourth stands F1 to F4 upstream of the fourth stand where the plate profile meter 20A is installed is the When the tip reaches the plate profile meter 20A, the plate profile at the tip is measured.

For the strip S that has reached the exit side of the fourth stand F4 with the first profile meter 20A between the fourth stands, the plate profile _Cr4 and the plate thickness at the center thereof are obtained.
After measuring h ₄ , these measured values are input to the plate profile control arithmetic unit 16, where they are converted into the ratio crown R _c4 . The fourth based on this measured value
The plate profile control devices 10A and 10A before the fourth stand and the plate profile control devices of the first to third stands (not shown) are arranged so that the ratio crown on the exit side of the stand F4 matches the target ratio crown _Rc4 ^Aim obtained in advance. The control change amount is output from the profile control calculation device 16 to perform feedback control.

By the above feedback control, the fourth
After measuring the plate profile at the tip of the strip between the stands, the plate profile on the exit side of the fourth stand F4 can be matched with the target ratio crown on the exit side of the stand F4. Therefore, thereafter, it is possible to advance the rolling by the downstream stands F5 to F7 under the condition of the fixed ratio crown, and the product strip rolled by the seventh stand F7 can be moved to the target plate without causing disorder of flatness. You can hit your profile.

As described above, in the present embodiment, the fourth
Since the plate profile meter 12A is provided between the stand F4 and the fifth stand F5, the plate crown _Cr4 on the exit side of the fourth stand can be obtained as an actual value instead of an assumed value as in the related art. Thus, the control accuracy of the plate profile can be greatly improved.

Further, since the thickness of the strip passing between the fourth stands on which the plate profile meter 20A is installed is set to 4 mm or less and 2 mm or more, the upstream stands F1 to F4 have the plate thickness. There is a high degree of freedom to change the crown without disturbing the shape. Therefore, the error S ₄ in the fourth stand F4 is directly calculated by the same method as described above using the equation (8), the error S ₄ is reduced, and the measured ratio crown R _c4 in the stand is calculated. Target ratio crown R _c4 ^Aim
The roll deflection C due to the rolling load is adjusted to match
By changing the crown control amount to correct _mp4 , it is possible to execute highly responsive feedback control.

In addition to performing the above-described feedback control, if there is a deviation between the ratio crown based on the actual measurement and the target value between the fourth stands, the final product plate profile and the target plate on the exit side of the seventh stand. In order to reduce the deviation from the profile, the stands on the downstream side of the fourth stand F4 from the plate profile control calculation device 16, that is, the fifth stand F5, the sixth stand F6, and the seventh stand
The control change amount is output to the load cells 12B, 12C, and 12D attached to the stand F7 to perform feedforward control.

That is, according to the deviation between the ratio crown and the target ratio crown based on the actual measurement of the strip leading end, the plate profiles respectively disposed on the rolling stands F5 to F7 located downstream of the first plate profile meter 20A. The required control amounts calculated by the plate profile control arithmetic unit 16 are also output to the control devices 10B to 10D in order to correct the plate profile at the tip of the strip. However, in these downstream rolling stands 10B to 10D, since the controllable amount of the plate profile is small as described above, the output to the plate profile control devices 10B to 10D is controlled so as to be within the allowable range of flatness. It is necessary to add a restriction by calculation in the calculation device 16.

However, in the present embodiment, the strip whose plate profile is measured by the plate profile meter 12A has a plate thickness of 4 mm or 2 mm or more. Since a relatively large allowable range of the flatness can be ensured, the plate profile control can be reliably performed without causing a plate shape (flatness) defect.

The following two methods are used to control the downstream stands F5 to F7 to bring the final ratio crown closer to the target value on the basis of the measured ratio crown _Rc4 on the exit side of the fourth stand. Can be mentioned.

The first method predicts a plate profile on the exit side of the final stand when the rolling is advanced to the final stand in accordance with a preset pass schedule based on the ratio crown R _c4 obtained from the measured plate profile. This is a method of controlling the downstream stands F5 to F7 to bring the predicted delivery plate profile closer to the target value. In this case, the predicted plate profile on the exit side of the final stand can be obtained by the above equations (1) to (7).
Further, the ratio crown change amount for each of the stands F5 to F7 can be obtained by the above equation (11).

The second method is that, before the leading end of the strip passes through the final seventh stand F7, the ratio crown _Rc4 obtained from the measured plate profile (plate crown) _{Cr4 at the} exit side of the fourth stand F4, The proportional integral control based on the deviation from the target ratio crown R _c4 ^Aim on the exit side is simply applied to the subsequent stands F5 to F7 to perform control.
After the end of the strip has added the seventh stand F7, the control is performed by the first method. In this case, the amount of change of the crown ratio with respect to each of the downstream stands F5 to F7 can be obtained by the above equation (9).

In the latter stand where the strip thickness becomes thinner, the shape is easily disturbed as described above, so that the changeable amount of the ratio crown _{Rci in} the _subsequent i-th stand is limited. Therefore, it is important to consider how to approach the target in the limit determined by the changeable amount ΔR _ci of the ratio crown determined by the following equation (13), in order to secure the passability.

ΔR _ci = f ₆ (h, b, D) (13)

In the control method based on the above equation (9), the changeable amount of the ratio crown in the downstream stand cannot be taken into account. However, in the method based on the above (11), this can be taken into account. Therefore, the control method based on the expression (11) is more advantageous than the control method based on the expression (9). Here, as described above, at the time of controlling the plate profile at the leading end of the strip, since there is no actual data after the fifth stand F5, it is meaningless to predict the plate crown up to the seventh stand F7 (9). A control method based on the expression (3) may be used.

In this embodiment, even after the leading end of the strip has passed between the fourth stands, the plate profile of the strip passing between the stands can be changed by continuing the measurement with the plate profile meter 20A. Even if there is a deviation between the measured plate profile and the target value due to changes due to thermal expansion or progress of wear, etc., it is possible to correct the deviation, so that the plate profile of the product always matches the target value. It becomes possible.

Next, the first plate profile meter 20
A description will be given of the result of actually performing the plate profile control in order to clarify the effect of the control method using the actually measured plate profile by A.

When rolling a sheet bar having a thickness of 30 mm in accordance with the pass schedules shown in Tables 1 and 2 below, the distance between the stands where the plate profile meters are installed is changed, and the plate is placed at a position where the thickness is different. In addition to measuring the profile, feedback control is performed for the stand on the upstream side of the plate profile meter installation position based on the measured plate profile. Plate profile control was performed, which performed forward control.

[0117]

[Table 1]

[0118]

[Table 2]

FIG. 4 shows the difference between the measured plate profile on the exit side of the final stand and the target value obtained when the above-mentioned plate profile control was performed and the plate profile control accuracy (μm
) And the correlation between this and the passing plate thickness (mm) between stands on which the plate profile meter is installed.

As is clear from FIG. 4, the control accuracy is improved when the passing plate thickness is 2 mm or more, and the control accuracy is reduced when the passing plate thickness exceeds 4 mm, and the control effect is finally lost.

The improvement of the control accuracy at a plate thickness of 2 mm or more is based on the fact that the ratio crown change limit determined by the shape limit rapidly increases as shown in FIG. It is shown in FIG.
It is understood that the genetic coefficient β _i decreases and the number of times of rolling until reaching the final product increases as shown in FIG.

From the above description, it is preferable that the position of the plate profile meter for measuring the plate profile used for the feedback control and the feedforward control be between stands where the thickness of the passing strip is 4 mm or less and 2 mm or more. It turns out there is.

In the present embodiment, the first plate profile meter 20A is provided between the fourth stands, and the second plate profile meter 20A is provided between the fifth stands continuous between the fourth stands.
Since the plate profile meter 20B is installed, the first
When performing the above-described plate profile control based on the actually measured plate profile obtained by the plate profile meter 20A, the fifth plate F5 using the actually measured plate crown _Cr5 on the exit side of the fifth stand F5 obtained by the second plate profile meter 20B is used. It is possible to control the stand.

Therefore, even in the fifth stand F5, it is possible to perform the plate profile control based on the actual measured value instead of the assumed value, so that the control accuracy can be further improved.

In this embodiment, as described above, the first
With measuring a fourth stand F4 delivery side of the strip crown C _r4 in the plate profile meter 20A, the fifth stand F5 delivery side by the second plate profile meter 20B strip crown C _r5,
Further, the roll profile C _MR5 work rolls of the same stand F5 roll profile meter 22, the rolling load P ₅ of the stand F5 were measured by further load meter 12B, the plate profile processing device these measured values 16
To enter.

[0126] In this arithmetic unit 16, determined by calculating the crown C _mp5 due to deflection rolls of the same stand F5 by the expression (6) from the rolling load P ₅ of the fifth stand F5, wherein it together with the measured value (1 ) Is applied to the model formula to obtain the above (5)
The mechanical crown transfer rate α _{i of} the equation and the genetic coefficient β _{i of the} equation (7) are obtained, and the learning correction coefficients (regression coefficient K _ch and shape change coefficient の 中) in these calculation model equations are changed to obtain the following. , The accuracy of the initial setting of the rolled material can be improved.

This will be described in more detail. As in the present embodiment, an arrangement is adopted in which plate profile meters 20A and 20B are provided between two stands sandwiching one rolling stand provided with a roll profile meter. By
Necessary stand F _i (i = 4) for the crown calculation by the above equation (1), the sheet crown C _ri on the exit side, the sheet crown C _ri-1 on the exit side of the preceding stand, and the roll of the object stand F _i . Since the sum (C _mRhi + C _mRwi ) of the crown due to thermal expansion and the crown due to roll wear can all be measured,
Consequently error component is only genetic factors beta _i and the transfer rate alpha _i. Therefore, the transfer rate α can be easily determined by a recursive method or the like.
_i and the genetic coefficient β _i can be optimized. Note that the transfer rate α _i and the genetic coefficient β _i vary depending on the temperature distribution in the width direction of the material, the material characteristics, and the like, and the change due to the difference between stands is small. Applying this to other stands does not cause any major problems.

In the present embodiment, in addition to the above-described plate profile control, the width-direction plate thickness control described below is also performed.

The thickness of the strip passing between the fourth stands at a specific position in the width direction is actually measured by the first plate profile meter 20A, and the measured thickness in the width direction and the predetermined target width direction between the stands are determined. If there is a deviation from the sheet thickness, feedback control of the width direction sheet thickness for correcting the rolling position with respect to the upstream side stand is performed to reduce the deviation. Here, the specific position in the width direction of the strip means a measurement position in the width direction corresponding to the sensor position of the plate profile meter 20A.

The feedback control of the thickness in the width direction is as follows.
For example, it can be performed by sequentially integrating the difference between the measured value of the sheet thickness at the specific position in the width direction and the target value, and correcting the rolling position in addition to the target value of the AGC of the preceding stand.

In this embodiment, the rolling positions of the downstream stands F5 to F7 are corrected on the basis of the thickness measured in the width direction by the first plate profile meter 20A, and the specific width direction positions on the exit side of the final stand F7. Feed-forward control is also performed to make the thickness of the steel sheet equal to the target value.

The first method of feed-forward control of the width-direction sheet thickness is to measure the width-direction sheet thickness, calculate the predicted width-direction sheet thickness at the exit side of the final stand F7 when the rolling is performed as it is, and calculate the predicted width-direction sheet thickness. In order to reduce the error between the width direction plate thickness and the stand F7 exit side and the target width direction plate thickness, the amount of correction of the rolling-down position is obtained by the above equation (12), and the amount of correction is similarly calculated by the plate thickness control devices 14B to 14D. Output to the

The second method of the feedforward control is based on the deviation between the measured value of the thickness in the width direction and the target value.
In order to reduce the error between the thickness in the width direction on the exit side of the final stand F7 and the target value, the amount of correction of the rolling-down position is obtained by the above equation (10), and the amount of correction is determined by the thickness control devices 14B to 14D of the downstream stand. This is a method of controlling by outputting to

In the present embodiment, the first plate profile meter 20A and the second plate profile meter 20B use the fourth plate profile meter 20A.
With measuring a central portion thickness h ₅ at the central portion thickness h ₄ and the fifth stand F5 exit side of the stand F4 outlet side, measuring a central portion thickness h ₆ of the sixth stand F6 delivery side by thickness gauge 24 The measured thicknesses are input to the thickness control arithmetic unit 18, and the arithmetic unit 18 compares the measured values with a preset target stand-to-stand thickness to reduce the deviation. By changing the control amount for the plate thickness control device 14 in such a manner, it is possible to control the central plate thickness with high accuracy.

Further, as described above, by installing the first profile meter 20A between the third fourth stand counted from the downstream side, the difference in the thickness of the strip passing through the measurement position in the width direction can be reduced. Can also be detected. Since the position between the fourth stands is a position where the plate profile can still be corrected, if there is a difference in plate thickness in the width direction, the fifth stand F5 and the sixth stand F6 located on the downstream side thereof.
By performing feedforward control on the seventh stand F7 so as to eliminate the deviation of the plate thickness occurring in the width direction, it is possible to prevent meandering from occurring in the final product of the strip S. By improving the meandering of the strip S in this manner, it is possible to reduce a passing trouble such as narrowing when the leading end and the trailing end pass.

Further, in this embodiment, since the flatness gauges 26 are provided between the stands, respectively, the shape of the strip S passing between the stands is measured by the flatness gauges 26, and the actual measurement plate is measured. By inputting the shape to the plate profile control arithmetic unit 16 and correcting the control correction amount from the detected values, it is possible to appropriately prevent the plate shape from being disturbed due to the plate profile overcontrol.

As described in detail above, according to the present embodiment,
Since the plate profile meter 20A is installed between the stands where the thickness of the strip passing therethrough is 4 mm or less and 2 mm or more, the upstream of the installation position of the plate profile meter 20A is determined based on the measurement result by the plate profile meter 20A. By performing feedback control on the rolling stands, the strip passing between the stands can be matched with the target plate profile at that position, and by performing feedforward control on the downstream stand, the plate profile meter is controlled. 20
Even if there is a deviation between the measurement result by A and the target value, the product plate profile on the exit side of the final stand can be hit to the target value. Actually, in the conventional method, the error of the plate profile control accuracy was 30 μm, but could be reduced to 10 μm or less.

Further, according to the above-mentioned feedback control, compared to the conventional case where a sheet profile meter is installed on the outlet side of the tandem rolling mill or in the vicinity thereof, the material required before the feedback control is applied is reduced. The length can be greatly reduced. By the way, when converting from the fourth stand exit side to the seventh stand exit side into the strip length,
For example, it is about 20 m.

Further, according to the feedforward control, since the plate profile control can be performed based on the actually measured value measured by the plate profile meter 20A, the control can be largely performed as compared with the conventional predictive control. Accuracy can be improved.

Further, according to the present embodiment, the plate profile between the stands, which was conventionally unknown, can be found, and the plate profile meter is installed on a rolling stand sandwiched between two consecutive stands. Since the roll profile for the rolling stand can be obtained as an actual measurement value by the roll profile meter, the plate profile on the entrance side and the exit side of the rolling stand and the state of the roll profile can be directly measured.

Therefore, the deviation of the mechanical crown transcription rate α _i and genetic coefficient β _{i from} the model formula can be quantitatively and directly grasped, so that the accuracy of the control model formula can be greatly improved. Thus, the initial setting accuracy for each control device at the time of rolling the next material can be greatly improved.

Further, according to the present embodiment, the width-direction thickness is controlled together with the thickness at the final stand exit side by performing feedback control and feed-forward control of the width-direction thickness based on the measured width-direction thickness. Can also hit the target value with high accuracy.

As described above, the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, in the above-described embodiment, the case where the finishing mill has seven stands has been described.

Further, in the finishing mill comprising the seven stands, the first plate profile meter 20A is passed through a plate having a thickness of 4 mm.
mm or less, it was installed between the 4th stand that was 2 mm or more,
It is not limited to this.

The installation positions and the numbers of the plate profile meter, the roll profile meter, and the flat thermometer are as follows.
The present invention is not limited to the embodiment described above, but can be arbitrarily changed, and is not limited to the case where the stands where the plate profile meters are installed are continuous.

Further, in the above embodiment, the case where the thickness gauge is installed between the sixth stand before the final seventh stand is shown, but a plate profile meter may be installed instead of the thickness gauge. . However, since the plate thickness is usually too thin between the stands, the degree of freedom in controlling the plate profile is extremely low. Therefore, it is advantageous from the economical point of view to install a thickness gauge as in the above embodiment between the final stands.

[0148]

As described above, according to the present invention, the thickness of the strip in the width direction and the thickness of the strip in the width direction together with the strip profile on the exit side of the final stand can be accurately set to the target value from the front end without causing a shape defect in the strip. Highly responsive rolling control can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the thickness of a plate passing between stands and the ratio crown change limit.

FIG. 2 is a diagram showing the relationship between genetic coefficient and plate thickness.

FIG. 3 is a schematic configuration diagram showing a part of an equipment arrangement of a hot strip finishing mill according to an embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a plate thickness at a stand-to-plate profile meter installation position and control accuracy.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Sheet profile control device 12 ... Load meter 14 ... Sheet thickness control device 16 ... Sheet profile control arithmetic device 18 ... Sheet thickness control arithmetic device 20 ... Sheet profile meter 22 ... Roll profile meter 24 ... Sheet thickness meter 26 ... Smoothness meter

──────────────────────────────────────────────────続 き Continuing from the front page (72) Nobuaki Nomura, Inventor No. 1, Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Hideyuki Nikaido 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba (56) References JP-A-59-197309 (JP, A) JP-A-5-111712 (JP, A) JP-B-54-8644 (JP, B2) (58) Fields investigated ( Int.Cl. ⁶ , DB name) B21B 37/28-37/44

Claims (1)

(57) [Claims] 1. A method for controlling rolling in a hot strip finishing mill in which a plurality of rolling stands are connected in series, wherein a plate profile of a strip passing between the stands is measured by a plate profile meter installed between the stands. Before the tip passes through the final stand, the error between the target plate profile at the exit of the final stand and the target value of the plate profile on the exit side of the final stand is reduced based on the deviation between the actual plate profile measured by the plate profile meter and the target plate profile at the actual measurement position. The plate profile control is performed on the rolling stand on the downstream side between the plate profile meter installation stands as described above, and the deviation between the measured width direction thickness measured by the plate profile meter and the target width direction thickness at the same measurement position. Based on the width of the plate thickness in the final stand exit side Correct the rolling position of the downstream rolling stand so as to reduce the error from the target value, and after the strip tip passes through the final stand, predict the plate profile at the exit of the final stand based on the measured plate profile. The plate profile control is performed on a rolling stand downstream from the plate profile meter installation stand so as to reduce an error between the predicted plate profile and the target plate profile on the final stand exit side. The width in the width direction on the exit side of the final stand is predicted based on the actually measured width in the width direction, and the downstream is set so as to reduce the error between the predicted width direction thickness and the target width direction thickness on the exit side of the final stand. The hot strip finishing mill is characterized in that the rolling position of the rolling stand on the side is corrected. Rolling control how.