JPH09168809A - Rolling control method for hot strip finishing mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To match the sheet profile on the outlet side of the final stand with the target value with high accuracy without generating defect in shape of a strip. SOLUTION: In a hot strip finishing mill which is composed by providing a 1st stand F4 to the 7th stand successively, based on the measured sheet profile with a sheet profile meter 20A provided between the 4th stand F4 and the 5th stand F5, the sheet profile on the outlet side of the final stand F7 is estimated and the stands F5-F7 on the downstream side are controlled by feedforward so as to reduce an error between the estimated sheet profile and the target sheet profile on the outlet side of the final stand F7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling control method in a hot strip finishing rolling mill, and more particularly to a hot strip finishing rolling mill capable of accurately hitting a strip plate profile on a delivery side of a final stand to a target value. The present invention relates to a rolling control method.

[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. Now, the crown caused by the deflection of the roll by rolling load C _mpi, the crown due to thermal expansion of the roll C _MRhi, a crown with a roll wear putting a 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).

[0026] Then, the (1) based on the equation, along with determining the target mechanical crown C _rmi ^Aim to achieve the target strip crown C _ri ^{Ai m} for each stand, crown control to achieve the target mechanical crown Determine the output of the device.

[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. Generally, 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.

The present invention has been made in order to solve the above-mentioned conventional problems, and the plate profile on the exit side of the final stand including the tip portion can be accurately set to the target value 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 hit the target.

[0040]

According to a first aspect of the present invention, in a rolling control method in a hot strip finishing mill in which a plurality of rolling stands are arranged in series, a strip profile meter installed between the stands is used to connect the stands. To actually measure the plate profile of the passing strip, predict the plate profile on the final stand exit side based on the measured plate profile, and reduce the error between the predicted plate profile and the target plate profile on the final stand exit side, The above problem is solved by controlling the rolling stand on the downstream side of the plate profile meter installation stand.

Further, in the invention of claim 2, in a rolling control method in a hot strip finishing rolling mill in which a plurality of rolling stands are connected in series, a strip profile meter installed between the stands is used to measure strips passing between the stands. The plate profile is actually measured, and before the strip tip passes through the final stand, the deviation between the measured plate profile obtained between the plate profile meter-installed stands and the target plate profile obtained in advance between the stands is obtained, The rolling stand on the downstream side is controlled based on the deviation, and after the strip tip passes the final stand, the strip profile on the exit side of the final stand is predicted based on the measured strip profile, and the predicted strip profile and the final strip profile are predicted. Reduce the error from the target plate profile on the stand-out side Sea urchin, by controlling the rolling stands downstream from between the plate profile meter position stand is obtained by solving the above problems as well.

The invention according to claim 3 is the rolling control method in the hot strip finishing mill according to claim 2,
A deviation between a measured plate profile obtained between the plate profile meter installation stands and a target plate profile obtained in advance between the stands is obtained, and a rolling stand upstream from the stand is arranged so as to reduce the deviation. The above problem is similarly solved by controlling.

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

As described above, in the latter stage of the hot strip finishing mill, it is extremely difficult to significantly change the plate profile because it causes defective plate shape in the product.

Generally, 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 phenomena, the present inventor has found that if there is a certain thickness of the sheet, even if residual stress distributed in the width direction occurs due to departure from the state in which the ratio crown is constant, the sheet shape 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 plate thickness and the ratio crown change limit without disturbing the plate shape, which is the basis of the above findings. The limit increases when the plate thickness is 2 mm or more.
It can be seen that the saturation gradually increases when it exceeds mm.

Here, the ratio crown change limit is the i-th limit.
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 estimated 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 becomes smaller, 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.

There is also 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 of the above 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 the disturbance due to subsequent rolling increases, so that the plate profile changes during 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, as a space between the stands for installing the plate profile meter, it is preferable that the plate shape is not disturbed even if the ratio crown is changed to some extent, and the thickness of the passing strip is 2 mm or more, preferably 2 mm or more. A space between stands of 4 mm or less is particularly preferable.

Here, in the case where the rolling stand on the downstream side is controlled based on the deviation between the actually-measured strip profile obtained between the strip profile meter installation stands and the target strip profile obtained in advance between the stands. Considering this, the actual ratio crown can be obtained from the measurement results, and the ratio crown can be changed within the allowable range shown in FIG. 1, for example, according to the deviation between the actual ratio crown and the target ratio crown. By changing the ratio crown within the above allowable range for the rolling stands on the downstream side between the installation stands, the plate profile on the exit side of the final stand can be hit to the target value without causing the plate shape to be disturbed. Is possible. The change amount of the plate crown applied to the downstream stand at that time can be obtained as follows.

For example, the plate claw on the exit side of the fourth stand F4
The actual measurement plate crown C _r4And the same stand F4
Outgoing target plate crown C_r4 ^AimDeviation ΔC from_r4The fifth
A description will be given of a case where the correction is performed on the stand F5.
Amount of change in sheet crown ΔC on the exit side of F5 stand F5_r5Is the following
It can be obtained by equation (9).

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

If the shape is disturbed by changing and controlling the plate crown only with the fifth stand F5 as described above, the fifth stand F5 and the sixth stand F6 or the fifth stand F5 may be used.
It is also possible to share and control the plate crown change amount by each of the plurality of stands of the seventh stands F5 to F7.
Further, the control can be performed only by the sixth stand F6 and only by the seventh stand F7.

However, in this method, the fourth
Although there is an effect of canceling the disturbance generated up to the stand F4, no consideration is given to the disturbance generated after the fifth stand F5.

According to the first aspect of the invention, the plate profile on the output side of the final stand is predicted based on the measured plate profile obtained between the plate profile meter installation stands, and the predicted plate profile and the target on the output side of the final stand. Since the rolling stand on the downstream side of the stand for installing the plate profile meter is controlled so as to reduce the error from the plate profile, the plate profile on the exit side of the final stand can be hit to the target value.

Thus, according to the first aspect of the invention,
The strip profile passing between the stands is measured by a strip profile meter installed between the stands instead of the exit side of the final stand, and rolling is performed on the downstream side of the strip profile meter installation stand based on the measured strip profile. Since the feed-forward control of the stand is performed, the plate profile on the exit side of the final stand can be made to match the target value by appropriately selecting the plate profile meter between the installed stands. The feedforward control can be performed by operating a profile control device (roll bender or roll crossing angle adjusting device) of the rolling stand.

At this time, the equations (1) to (7) are used to obtain the predicted plate profile on the exit side of the final stand based on the actually measured plate profile.

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 (1) to (7)
Use the formula.

[0064] 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, the fifth stand F5 delivery side of the strip crown the following equation (10) _Is changed by the change amount ΔC _r5 determined by

ΔC _r5 = (1 / β ₆ β ₇ ) ΔC _r7 (10) 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 second aspect of the present invention, before the strip tip passes through the final stand, the actually measured plate profiles obtained between the plate profile meter installation stands and the target plate obtained in advance between the stands. The deviation from the profile is obtained, the rolling stand on the downstream side is controlled based on the deviation, and after the strip tip passes the final stand, the strip profile on the exit side of the final stand is predicted based on the measured strip profile. In order to reduce the error between the predicted strip profile and the target strip profile on the exit side of the final stand, the rolling stands on the downstream side between the strip profile meter installation stands are controlled so that the strip tip is set to the final stand. Before passing, the control method based on the above equation (9) is performed to After the flop tip has passed the final stand, it is possible to perform a control method based on the expression (10).

Here, the difference between the control method based on the above equation (9) and the control method based on the above equation (10) 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 according to the equation (10) predicts the _strip crown _Cr7 on the exit side of the seventh stand based on the actually measured _strip crown _Cr4 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 Expression (10) predicts _Cr7 using the rolling results, and thus the influence of the disturbance that occurs after the fifth stand F5. Is also considered.

That is, in any one of the first and second aspects of the invention, the deviation from the target plate crown generated between the plate profile meter installation stands (hereinafter, also referred to as a specific stand), and between the specific stands and thereafter. In order to reduce the deviation from the target plate crown on the exit side of the final stand due to both of the disturbances that occur at the exit side of the final stand and to reduce the deviation from the target plate crown on the exit side of the final stand, Control the side stand.

The disturbance referred to here includes rolling load, deformation resistance, etc., but in the present invention, the disturbance after a specific stand can be obtained from the rolling record after the strip tip has passed the final stand. it can. However, before the strip tip passes the final stand, since there is no means for predicting the disturbance, the crown change amount of the stand on the downstream side between the specific stands is
The crown change amount is the same whether it is obtained by the equation (9) or the equation (10). Therefore, in the invention of claim 2, before the strip passes the final stand, a method of obtaining the crown change amount by the expression (9) is adopted.

According to the invention of claim 3, in the rolling control method of claim 2, the actually measured plate profile obtained between the stands for installing the plate profile meter and the target plate profile obtained in advance between the stands. When controlling the rolling stand on the upstream side between the stands so as to reduce the deviation, in addition to the feedforward control for the stand on the downstream side of the stand between the plate profile meter installations described above, Feedback control can be performed on the stand.

In this feedback control, the strip profile passing through the stands is measured by the strip profile meter at the time of strip running, and the target ratio crown is determined from the target strip profile of the product. By operating the profile control device (roll bender or roll crossing angle adjustment device) of the rolling stand on the upstream side of the plate profile meter installation position so that the actual ratio crowns obtained from the profile measurement results between You can

By performing this feedback control, for example, when there is a deviation between the measured plate profile and the target plate profile at that position, as a result of measuring the tip of the strip with the plate profile meter. However, after that point, it becomes possible to control the strip to the target strip profile at any time between the stands at the strip profile measurement position. It is possible to accurately hit the plate profile of the above with the target value.

[0076]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

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

The finish rolling mill used in the present embodiment is a continuous rolling mill consisting of a total of seven stands of the first stand F1 to the seventh stand F7, and in FIG.
4 to the seventh stand F7 are shown.

In the above continuous rolling mill, each stand is equipped with a plate profile control device 10, a load meter 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 above-mentioned fourth stand F4 to 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 plate thickness control calculation device 18 is connected to the plate thickness control devices 14A to 14D.
Thus, a control signal for controlling the thickness is input to each of the thickness control devices 14A to 14D.

Also, the fourth stand F4 and the 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.

Also, 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 installed between each of the fourth, fifth and sixth stands so that the flatness of the strip passing between the stands can be measured. .

Next, the operation of this embodiment will be described in the case where the above (1) is used as the plate profile control formula.

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

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

With respect to the strip S which has reached the exit side of the fourth stand F4 by the first profile meter 20A between the fourth stands, the plate profile C _r4 and the plate thickness of the central portion thereof are set.
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 installed between the stand F4 and the fifth stand F5, the plate crown C _r4 on the _delivery side of the fourth stand can be obtained as the actual value instead of the assumed value as in the conventional case. It is possible to significantly improve the control accuracy of the plate profile.

Further, since the thickness of the strip passing between the fourth stands in which the plate profile meter 20A is installed is set to be 4 mm or less and 2 mm or more, the plates are not used in the upstream stands F1 to F4. 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 the above feedback control, when there is a deviation between the measured ratio crown 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 are determined. 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 arithmetic unit 16, that is, the fifth stand F5, the sixth stand F6 and the seventh stand F4.
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 based on the actual measurement of the strip leading end and the target ratio crown, the strip profiles respectively provided on the rolling stands F5 to F7 located downstream of the first strip profile meter 20A. The necessary control amounts calculated by the plate profile control calculation device 16 are output to the control devices 10B to 10D so as 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 for measuring the plate profile with the plate profile meter 12A has a plate thickness of 4 mm, 2 mm or more, so that the ratio crown change limit illustrated in FIG. Since it is possible to secure a relatively large allowable range of the flatness, it is possible to reliably perform the plate profile control without causing a plate shape (flatness) defect.

The following two methods are available for controlling the downstream side stands F5 to F7 to bring the final ratio crown close to the target value based on the above-mentioned measured ratio crown R _c4 on the exit side of the fourth stand. Can be mentioned.

The first method is to predict the strip profile on the delivery side of the final stand when rolling is advanced to the final stand according to a preset pass schedule based on the ratio crown R _c4 obtained from the measured strip profile. A method of controlling the downstream stands F5 to F7 in order to bring the predicted output board profile close 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).
The amount of change in the ratio crown for each of the stands F5 to F7 can be obtained by the above equation (10).

In the second method, before the strip tip passes through the seventh stand F7, the ratio crown R _c4 obtained from the actually measured plate profile (plate crown) C _r4 on the fourth stand F4 outlet side and the same stand outlet side. At the downstream stand F due to the deviation from the target ratio crown R _c4 ^Aim at
This is a method of controlling so as to cancel the plate crown error generated in 5 to F7, and controlling by the above-mentioned first method after the strip tip has passed the seventh stand F7. In this case, the amount of change in the crown ratio for each of the downstream stands F5 to F7 before the strip tip passes through the seven stands F7 can be obtained by the above equation (9).

Rear stand with thin strip thickness
As described above, since the shape is easily disturbed as described above, the i-th
Ratio R_ciThe changeable amount of
I can. Therefore, the above ratio determined by the following equation (11)
Changeable amount of rate crown ΔR _ciWithin the limits determined by
Considering whether or not to approach the target will secure the passability
Is important in

ΔR _ci = f ₆ (h, b, D) (11)

The control method based on the above equation (9) cannot consider the changeable amount of the ratio crown in the downstream stand, but the method based on the above (10) can take this into consideration. Therefore, the control method based on the equation (10) is more advantageous than the control method based on the equation (9). Here, as described above, when controlling the strip profile of the strip front end, it is meaningless to predict the strip crown up to the seventh stand F7 because there is no actual data after the fifth stand F5 (9 ) A control method based on the equation may be used.

Further, in this embodiment, even after the tip of the strip passes between the fourth stands, the plate profile meter 20A continues the measurement, so that the strip plate profile passing between the stands is rolled. Even if there is a deviation between the actual measurement plate profile and the target value that changes due to thermal expansion or progress of wear, the deviation can be corrected, so that the product plate profile can always match the target value. It will be 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 plate thickness of 30 mm in accordance with the pass schedules shown in the following Tables 1 and 2, the stands between which the plate profile meter is installed are changed so that the plate bars are placed at different positions. In addition to measuring the profile, feedback control is performed on the stand upstream from the plate profile meter installation position based on the measured plate profile, and the stand downstream from the plate profile meter installation position is fed under a constant ratio crown condition. The plate profile was controlled by performing the forward control.

[0104]

[Table 1]

[0105]

[Table 2]

FIG. 4 shows the error between the measured plate profile and the target value at the exit side of the final stand obtained when the plate profile control is carried out as 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, when the thickness of the passing plate is 2 mm or more, the control accuracy is improved, and when it exceeds 4 mm, the control accuracy is lowered, and finally the control effect is lost.

The improvement of the control accuracy at the plate thickness of 2 mm or more is due to the rapid increase of the ratio crown change limit determined by the shape limit as shown in FIG. If it exceeds, it will decrease as 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, the installation position of the plate profile meter for measuring the plate profile used for the feedback control and the feedforward control is preferably between the stands where the plate thickness of the passing strip is 4 mm or less and 2 mm or more. I know there is.

In this embodiment, the first plate profile meter 20A is installed between the fourth stands, and the second plate is installed between the fifth stands which are continuous between the fourth stands.
Since the plate profile meter 20B is installed,
When performing the above-described plate profile control based on the actually measured plate profile obtained by the plate profile meter 20A, the measured plate crown C _r5 on the exit side of the fifth stand F5 obtained by the second plate profile meter 20B is used to perform the fifth plate profile control. It becomes possible to control the stand.

Therefore, even in the fifth stand F5, the plate profile control can be performed based on the actually measured value instead of the assumed value, so that the control accuracy can be further improved.

Further, in this embodiment, as described above, the first
While measuring the plate crown C _r4 on the exit side of the fourth stand F4 with the plate profile meter 20A, the plate crown C _r5 on the exit side of the fifth stand F5 is measured with the second plate profile meter 20B.
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.

In the arithmetic unit 16, the crown C _mp5 due to the roll deflection of the stand F5 is calculated from the rolling load P ₅ of the fifth stand F5 by the equation (6), and this is calculated together with the actual measurement value in the above (1). ) Is applied to the model equation of
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, the plate profile meters 20A and 20B are arranged between two stands sandwiching one rolling stand equipped with a roll profile meter. Due to
The plate crown C _ri of the target stand F _i (i = 4) on the _delivery side, the plate crown C _{ri-1 on} the _delivery stage of the preceding stand, and the rolls of the target stand F _i , which are necessary for the crown calculation by the equation (1), Since the sum of the crown due to thermal expansion and the crown due to roll wear (C _mRhi + C _mRwi ) can be measured,
As a result, the only error factors are the transfer rate α _i and the genetic coefficient β _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.

Further, in the present embodiment, the first plate profile meter 20A and the second plate profile meter 20B have a fourth profile.
Measure the central plate thickness h ₄ on the outlet side of the stand F4 and the central plate thickness h ₅ on the outlet side of the fifth stand F5, and measure the central plate thickness h ₆ on the outlet side of the sixth stand F6 with a plate thickness gauge 24. It is possible to input the measured thicknesses to the plate thickness control computing device 18, and the computing device 18 compares these measured values with the preset stand-to-stand target plate thickness and reduces the deviation. By changing the control amount for the plate thickness control device 14 as described above, the plate thickness can be controlled with high accuracy.

As described above, by installing the first profile meter 20A between the third and fourth stands 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 meters 26 are arranged between the stands, the flatness meter 26 measures the plate shape of the strip S passing between the stands, and the measured plate By inputting the shape to the plate profile control arithmetic unit 16 and correcting the control correction amount from these 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 this embodiment,
Since the plate profile meter 20A is installed between the stands where the plate thickness of the passing strip is 4 mm or less and 2 mm or more, based on the measurement result by the plate profile meter 20A, the plate profile meter 20A on the upstream side is installed. 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 strip profile meter can be obtained. 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 feedback control, compared with the conventional case where the plate profile meter is installed on the exit side of the tandem rolling mill or in the vicinity thereof, the material required before the feedback control is applied. 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, the plate profile control can be performed based on the actual measurement value measured by the plate profile meter 20A, so that the control is greatly controlled as compared with the conventional predictive control. It is possible to improve accuracy.

Further, according to the present embodiment, the plate profile between the stands, which has been unknown in the past, is found, and the plate profile meter is installed on the rolling stand sandwiched between two continuous stands. Since the roll profile of the rolling stand can be obtained as an actual measurement value by the roll profile meter, it becomes possible to directly measure the conditions of the strip profile and the roll profile on the inlet side and the outlet side of the rolling stand.

Therefore, it is possible to quantitatively and directly grasp the deviation between the transfer rate α _i of the mechanical crown and the genetic coefficient β _i with respect to the model formula, so that the accuracy of the control model formula can be greatly improved. Therefore, it is possible to significantly improve the initial setting accuracy for each control device when rolling the next material.

Although the present invention has been specifically described above, the present invention is not limited to the one shown in the above embodiment, and various modifications can be made without departing from the scope of the invention.

For example, in the above-described embodiment, the finish rolling mill has seven stands, but the present invention is not limited to this.

Further, in the finish rolling mill consisting of the above-mentioned 7 stands, the first plate profile meter 20A has a passing plate 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.

Further, the installation positions and the numbers of the plate profile meter, roll profile meter and flatness meter are not limited to those shown in the above-mentioned embodiment, but can be arbitrarily changed, and the plate profile meter can be installed. It is not limited to the case where the stands are also continuous.

Further, in the above-mentioned embodiment, the case where the plate thickness gauge is installed between the sixth stands before the final seventh stand is shown, but a plate profile meter may be installed instead of this plate 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 economically advantageous to install the plate thickness gauge between the final stands as in the above embodiment.

[0128]

As described above, according to the present invention, the plate profile on the exit side of the final stand, including the leading end, can be hit with the target value with high accuracy without causing a strip shape defect. And highly responsive plate profile 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 finish rolling 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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideyuki Yuzawa, Inventor 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Chiba Works, Kawasaki Steel (72) Nobuaki Nomura 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Works Co., Ltd. Chiba Steel Works (72) Inventor Hideyuki Nikaido 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Works Chiba Works

Claims (3)

[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.
The plate profile on the exit side of the final stand is predicted based on the measured plate profile, and the plate profile meter is installed between the stands on the downstream side so as to reduce the error between the predicted plate profile and the target plate profile on the exit side of the final stand. Control method for a hot strip finish rolling mill, comprising controlling the rolling stand of the above. 2. A rolling control method in a hot strip finishing rolling mill comprising a plurality of rolling stands connected in series, wherein a plate profile meter installed between stands measures the plate profile of a strip passing between the stands, and strips are measured. Before the tip passes the final stand, the deviation between the measured plate profile obtained between the plate profile meter installation stands and the target plate profile obtained in advance between the stands is calculated, and the downstream is calculated based on the deviation. After the strip front has passed through the final stand by controlling the rolling stand on the side, the plate profile on the exit side of the final stand is predicted based on the measured plate profile, and the predicted plate profile and the target plate profile on the exit side of the final stand are predicted. To reduce the error between Rolling control method in hot strip finishing mill and controlling the rolling stand downstream of the inter Irumeta installation stand. 3. The deviation according to claim 2, wherein a deviation between a measured plate profile obtained between the stands for installing the plate profile meter and a target plate profile obtained in advance between the stands is calculated, and the deviation is reduced. A rolling control method in a hot strip finishing rolling mill, comprising controlling a rolling stand upstream of the stand.