JPH06114422A - Method for controlling rolling in hot strip finishing mill - Google Patents

Abstract

PURPOSE:To make a plate profile on the outlet side of a final stand hit to a target value with high accuracy without generating a shape defect on a strip. CONSTITUTION:In a hot strip finishing mill wherein a 1st stand F1-a 7th stand F7 are juxtaposed, downstream stands F5-F7 are brought in feedforward control based on a measured result by a plate profile meter 20A equipped between the 4th stand F4 and the 5th stand F5. Further, each stand on the upstream side is made into feedback control so that an actual plate profile by the plate profile meter 20A is matched with a target sheet profile.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling rolling in a hot strip finishing mill, and more particularly to a hot strip finishing mill capable of accurately hitting a strip plate profile on the 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 rolling mill, control is performed to adjust the plate thickness as well as the plate thickness distribution in the width direction (plate profile) and the flatness of the plate.

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

Therefore, normally, a plate profile meter for actually measuring the plate profile is installed on the exit side of the final stand of the finishing rolling mill, and the plate of the product rolled by the final stand is used by using the measurement result of the plate profile meter. By controlling the profile and learning the plate profile control model, the control deviation for the next rolled material is reduced.

In the above plate profile control, for example, a control model equation represented by the following equation (1) can be used. In the case of a tandem rolling mill having N stands, each stand corresponds to the equation (1). By setting up the equations for the above and making a total of N equations in parallel, the plate profile on the delivery side of the final stand can be obtained.

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

In the above equation (1), C _ri is the plate profile on the i-th rolling stand exit side counted from the upstream side, C _ri
rmi is the so-called mechanical crown of the same stand, C
_ri-1 is the i-1th, that is, the plate profile on the exit side of the front stand, α _i is the transfer rate of the mechanical crown,
β _i is the 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 amount of mechanical change in the widthwise distribution of the roll gap caused by roll deflection due to rolling load, roll thermal expansion, or roll wear. _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). Be done.

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

In the above equation (2), the crown C _mpi due to roll deflection is based on the load distribution in the width direction (i) deflection of work roll and backup roll (including change due to crown controller output), and (ii) It is given by the function f ₁ expressed by the following equation (3), taking into consideration the initial crown of the roll. However, in this calculation formula, P is the rolling load, b is the material width, and x is the output of the crown controller.

C _mpi = f ₁ (P, b, x) (3)

Further, the crown (heat crown) C _mRhi due to the thermal expansion of the roll is mathematically expressed by a method such as a first-order response delay approximation for the change of the roll crown accompanying the progress of rolling and cooling after rolling, and each time constant and proportional It can be determined by regressing constants and the like from experimental data.

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

Also, the crown C _mRwi due to the roll wear is
Is expressed by the following equation (4) including the function f ₂ . However,
Cf is the wear coefficient, L is the rolling length, and D is the roll diameter.

C _mRwi = C f · f ₂ (P, L, b, D) (4)

In the above equation (4), Cf is determined by regression of the rolling result, but since the degree of roll wear changes depending on the material characteristics and the surface condition of the roll, this estimates the crown C _mRwi due to roll wear. It becomes the cause of the error.

In the 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)

Where h is the outgoing plate thickness, Ld is the contact arc length,
Kch is a regression coefficient that changes depending on the plate width, contact arc length, deformation resistance, etc., and ξ is a shape change coefficient given by a function f ₄ represented 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). In addition, H is the entrance side plate thickness.

Β _i = f ₅ (Kch, Ld, ξ, h, H) (7)

The transfer rate α _i of the above equation (5) and the above (7)
Since the genetic coefficient β _i of the equation uses the regression coefficient Kch and the shape change coefficient ξ, which is also recursively obtained, as variables, α _i and β _i are respectively determined recursively based on the experimental results. .

The following is a specific example of a conventional general strip profile control method using the above formula (1) in the case of a hot strip finishing rolling mill having a total of seven stands including a first stand F1 to a seventh stand F7. As described below.

First, assuming a pass (passing) schedule for performing finish rolling, the rolling load for each stand is predicted and calculated, and the exit side plate thickness of the finish rolling mill, that is, the exit side plate thickness of the seventh stand h ₇ And the target plate crown C of the 7th stand
_r7 ^Aim Final target ratio crown R _c7 ^Aim (= C
_r7 ^Aim / h ₇ ) and using this, the target crown C _ri of each stand from the above pass schedule
Determine ^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.

After that, actual strip rolling is performed, the outgoing side plate crown C _r7 of the final stand F7 is measured by a strip profile meter installed on the outgoing side of the stand, and the actual ratio outgoing side crown C _r7 to the actual ratio crown R are measured. _c7 (= C _r7 / h
₇ ) Ask.

[0028] Then, assume each stand outlet side of the ratio crown was equal to the actual ratio crown R _c7 seventh stand F7 delivery side, from the rolling load results and performance ratio crown R _c7 in each stand, each stand The error S _i from the equation (1) is calculated. That is, the _output side plate crown C _ri of the i-th stand is obtained as R _c7 × h _i , and the error S _i that establishes the following expression (8) is obtained. The mechanical crown C _rmi is calculated using the actual rolling load.

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

Regarding each stand as described above (8)
After obtaining the formula, learning is performed to use the formula (8) for setting the crown of the next material. Further, by using the error S _i , an appropriate mechanical crown C _mri for matching the output side plate crown of each stand with the target value is obtained, and the crown controller output for each stand is changed so as to match with the mechanical crown. , Feedback control is performed.

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

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

Therefore, in order to prevent the shape of the stand from being disturbed, a method of controlling from the stand on the more upstream side is disclosed in JP-A-60-127013 and JP-A-63-1990.
99, JP-A-1-266909. Generally, in hot rolling, the plate thickness is small and the crown control capability is small in the latter stage stand, so control before the middle stage of the finishing mill is effective. Therefore, in this respect, the method disclosed in each of these publications is an effective control method because the upstream stand is controlled in depth.

Further, JP-A-62-168608 and JP-A-2
-37908 also discloses a method of installing and controlling a plate profile meter on the inlet side of a tandem rolling mill.

Further, in Japanese Patent Laid-Open No. 59-39410, the plate profile is measured by the front stand, and the plate profile is controlled by the front stand based on the measured value.
A method is disclosed in which the shape is roughly controlled by the 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, in the method disclosed in the above-mentioned JP-A-60-127013, etc.,
Since the transfer time between the stands is long, the control system has a long dead time, and there is a problem that only the control with bad response can be performed.

Further, in the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 62-168608, the metal flow in the strip width direction is large in the front stand during hot rolling, and the variation of the strip profile on the inlet side of the tandem rolling mill is large. Since the influence is small, there is a problem that there is almost no plate profile control effect.

Further, in the method disclosed in the above-mentioned JP-A-59-39410, the plate profile is controlled by feedback control in the front stand after the front end passes through the front stand, so that the plate profile of the front end is controlled. There is a problem that it has no effect on control.

The present invention has been made to solve the above-mentioned conventional problems, and the plate profile on the delivery side of the final stand, including the tip, can be set to a target value with high accuracy without causing a defective shape of the strip. An object of the present invention is to provide a rolling control method in a hot strip finishing rolling mill having high responsiveness, which can be accurately targeted.

[0040]

DISCLOSURE OF THE INVENTION The present invention provides a rolling control method in a hot strip finishing mill in which a plurality of rolling stands are connected in series, and a strip profile meter installed between the stands is used to pass between the stands. By measuring the strip profile of, the rolling stand on the downstream side between the strip profile meter installation stands is controlled based on the measured strip profile, and by matching the strip profile on the exit side of the final stand with the target value, the above problems can be solved. It has been achieved.

The present invention also relates to a rolling control method in a hot strip finishing rolling mill, wherein a deviation between an actually measured plate profile obtained between the stands for installing the plate profile meter and a target plate profile obtained in advance between the stands. And by controlling the rolling stand on the downstream side based on the deviation, the above-mentioned object is achieved in the same manner.

In the rolling control method of the hot strip finishing mill, the present invention predicts the plate profile on the delivery side of the final stand based on the measured plate profile obtained between the stands for installing the plate profile meter, and predicts the prediction. By controlling the rolling stand on the downstream side so as to reduce the error between the strip profile and the target strip profile on the exit side of the final stand, the above-mentioned object is similarly achieved.

The present invention further provides, in the rolling control method for a hot strip finishing rolling mill, a deviation between an actually measured plate profile obtained between the stands for installing the plate profile meter and a target plate profile obtained in advance between the stands. Then, the rolling stand on the upstream side of the space between the stands is controlled so as to reduce the deviation, and the above problem is similarly achieved.

[0044]

First, the 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 plate profile meter installed at this position.

As described above, in the latter stage of the hot strip finishing rolling 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 plate shape, it is necessary to perform rolling with the ratio crown of the plate kept constant.

As a result of various studies on the rolling phenomenon, the present inventor has found that if there is a certain thickness of plate, even if residual stress distributed in the width direction due to deviation from a state where the ratio crown is constant occurs It was 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 that does not disturb the plate shape which is the basis of the above findings. The limit becomes larger when the plate thickness is 2 mm or more, 4
It can be seen that when it exceeds mm, it is gradually saturated.

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

Although FIG. 1 shows the experimental results, the reason why the ratio crown changing limit is saturated when the plate thickness exceeds 4 mm as described above is estimated as follows. In the thick plate region, buckling due to internal stress is unlikely to occur even if the ratio crown is changed, but conversely, it is considered that the presence of 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 widthwise central portion and tension acts on the widthwise end portion. As a result, the rolling load increases in the widthwise central portion, and conversely, the rolling load decreases in the edge portion. Since this tendency is stronger as the plate thickness is larger, the widthwise distribution of the rolling load is changed as a result even if the ratio crown is changed, which is considered to limit the change margin of the ratio crown.

Naturally, there is also a limit on the crown changeable amount of the crown control device. This is also considered to be a factor that limits the amount of change in the ratio crown on the thicker side.

Further, the genetic coefficient β of the equation (1) shown in FIG.
From one example of the relationship between i and the plate thickness, β _i is small when the plate thickness is large, but since the disturbance due to subsequent rolling increases, the plate profile changes during rolling to the exit side of the final stand, and as a result, the final Since the plate profile controllability of the product is reduced, even if the plate profile at a stage where the plate thickness is too large is actually measured, 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. A space between stands of 4 mm or less is particularly preferable.

In the present invention, the plate profile of the strip passing between the stands is measured by a plate profile meter installed between the stands rather than on the exit side of the final stand, and the plate profile meter is measured based on the measured plate profile. Since the rolling stand on the downstream side between the installation stands is feedforward-controlled, it is possible to match the plate profile on the exit side of the final stand with the target value by appropriately selecting the above-mentioned plate profile meter between the installation stands. it can. This feedforward control can be performed by operating a profile control device (roll bender or roll intersection angle adjusting device) of the rolling stand.

In the present invention, the rolling stand on the downstream side is controlled on the basis of a deviation between a measured strip profile obtained between the strip profile meter installation stands and a target strip profile obtained in advance between the stands. In this case, the actual ratio crown can be obtained from the measurement result, and the ratio crown can be changed 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 allowable range for the rolling stands on the downstream side between the profile meter installation stands, the strip profile on the exit side of the final stand hits the target value without disturbing the strip shape. It becomes possible. The change amount of the plate crown given to the downstream stand at that time can be obtained as follows.

For example, the plate crowd on the exit side of the fourth stand F4
The measured plate crown C _r4Same stand F4
Target plate crown C on the output side_r4 ^AimDeviation ΔC_r4The fifth
Explaining the case of correcting with the stand F5,
5 Stand F5 Plate crown change amount on exit side ΔC_r5Is the next
It can be obtained by the equation (9).

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

When the plate crown is changed and controlled only by the fifth stand F5 as described above and the shape is disturbed, the fifth stand F5 and the sixth stand F6 or the fifth stand F5 is used.
The plate crown change amount may be shared by each of the plurality of seventh stands F5 to F7 for control. Further, the control can be performed only by the sixth stand F6 and only the seventh stand F7.

In the present 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 plate profile on the output side of the final stand. When controlling the rolling stand on the downstream side between the stands for installing the strip profile meter so as to reduce the error between the strip profile meter and the strip profile meter, the strip profile on the delivery side of the final stand can be hit to the target value.

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

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

Similarly, the case of measuring the plate crown on the exit side of the fourth stand F4 will be described.
In order to predict and calculate the plate crown on the 7th stand F7 output side from the measured plate crown C _r4 on the 4th output side, the above (1) to (7) are used.
Use a formula.

In order that the predicted plate crown C _r7 on the outlet side of the seventh stand F7 becomes the target plate crown C _r7 ^Aim on the outlet side of the same stand, for example, the plate crown on the outlet side of the fifth stand F5 is expressed by the following equation (10). Change only the amount of change ΔC _r5 obtained in.

ΔC _r5 = (1 / β ₆ β ₇ ) ΔC _r7 (10) where; ΔC _r7 = C _r7 −C _r7 ^Aim

When the shape is disturbed by controlling only the fifth stand F5 as described above, when the downstream stand is changed by using the deviation between the measured plate crown of the fourth stand F4 and the target plate crown. Similarly to the above, a plurality of stands may share and control.

Here, the difference between the control method based on the equation (9) and the control method based on the equation (10) will be described.

The method according to the equation (9) is performed by the fourth stand F4.
This is a method of eliminating the error (deviation) ΔC _r4 = C _r4 −C _r4 ^Aim detected on the output side, which is caused by the fifth stand F5 and thereafter. When controlling the plate profile of the strip tip, since there is no actual data after the fifth stand F5 (because the strip is not caught), the seventh stand F7
This method is taken because it does not make sense to predict the plate crown up to.

On the other hand, the method according to the equation (10) predicts the plate crown C _r7 on the outlet side of the seventh stand based on the measured plate crown C _r4 on the outlet side of the fourth stand. In this prediction, unlike the prediction at the time of setting calculation, the actual value during rolling is used to predict C _r7 . That is, in the method of the formula (9),
In contrast to the control that only cancels the disturbance that occurs up to the fourth stand F4, the method according to equation (10) predicts C _r7 using the actual rolling results, and thus the influence of the disturbance that occurs after the fifth stand F5. Will also be considered.

Further, in the present invention, the deviation between 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 is calculated, and the deviation is reduced so as to reduce the deviation. When controlling the rolling stand on the upstream side between the stands, it is possible to perform the feedforward control on the stand on the downstream side between the stands for installing the plate profile meter and the feedback control on the stand on the upstream side.

This feedback control measures the strip profile of the strip passing between the stands with the strip profile meter at the time of stripping, determines the target ratio crown from the target strip profile of the product, and uses the stand as the target ratio crown. 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, so that after that, by rolling under the condition that the ratio crown is constant, the product at the exit side of the finish rolling mill can be controlled. It is possible to accurately hit the plate profile of the above with the target value.

[0073]

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

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

The finish rolling mill used in this embodiment is
It 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.
Up to the seventh stand F7 is shown.

In the above continuous rolling mill, each stand has a plate profile meter 10, a load meter 12, and a plate thickness control device 1
4 and. In addition, about these, about the 4th stand F4-7th stand F7, although the above-mentioned code | symbol is attached | subjected to the subscripts of A-D, respectively, it is shown, but also omitted 1st stand F1-third stand F3 It has the same configuration.

The above-mentioned fourth stand F4 to seventh stand F7
The plate profile control arithmetic units 16 are connected to the plate profile control units 10A to 10D.
Therefore, 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.
Therefore, a control signal for controlling the plate thickness is input to each of these plate thickness control devices 14A to 14D.

Also, the fourth stand F4 and the fifth stand F5
Between the fourth stands, between the fifth stand F5 and the sixth stand F6, and the final seventh.
On the exit side of the stand F7, the first plate profile meter 2
0A, a second plate profile meter 20B, and a third plate profile meter 20C are provided respectively,
The actual plate profile measured by the 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 by 2 is similarly input to the plate profile control computing device 16.

Further, the sixth stand F6 and the seventh stand F7
Between the 6th stand which is between the 6th stand, and the exit side of the 7th stand F7, the 1st board thickness gauge 24A and the 2nd board thickness meter 24B are installed, respectively, and the measurement board measured by these board thickness gauges 24A, 24B. The thickness is input to the plate thickness control calculation device 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 for the case where the above (1) is used as the plate profile control formula.

In the present embodiment, the strip passing between the fourth stand F4 and the fifth stand F5 (between the fourth stands), that is, the strip rolled by the fourth stand F4 has a plate thickness of 4 mm or less and 2 mm. The pass schedule is set as described above.

In this 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.
When h ₄ and are measured, these measured values are input to the plate profile control arithmetic unit 16 and converted into a ratio crown R _c4 in the arithmetic unit 16. Fourth based on this measured value
The plate profile control device 10A before the fourth stand and the plate profile control devices of the first to third stands (not shown) are set so that the ratio crown on the exit side of the stand F4 matches the target ratio crown R _c4 ^Aim that is obtained in advance. The control change amount is output from the profile control arithmetic unit 16 to perform feedback control.

By the above feedback control, the fourth
After measuring the strip profile at the tip of the strip between the stands, the strip profile on the exit side of the fourth stand F4 can be made to match the target ratio crown on the exit side of the same stand F4. Therefore, thereafter, it becomes possible to proceed with the rolling by the downstream side stands F5 to F7 under the condition that the ratio crown is constant, and the product strip rolled by the seventh stand F7 can be processed by the target plate without disturbing the flatness. It is possible to hit the profile.

As described above, in the present embodiment, since the plate profile meter 12A is installed between the fourth stand F4 and the fifth stand F5, the plate crown C _r4 on the _delivery side of the fourth stand is _replaced by the conventional one. Since it is possible to obtain the actual value instead of the assumed value as described above, 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 provided 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 at 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 at the stand is calculated. Target ratio Crown R _c4 ^Aim
Of the roll due to the rolling load so that
By changing the crown control amount to correct _mp4 , it becomes possible to execute feedback control with high responsiveness.

In addition to performing 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 delivery 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 arithmetic unit 16, that is, the fifth stand F5, the sixth stand F6 and the seventh stand F4.
The amount of control change 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 plate profiles respectively arranged on the rolling stands F5 to F7 located downstream of the first plate 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 that the flatness is within the allowable range. It is necessary for the arithmetic unit 16 to impose restrictions by arithmetic operations.

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 a 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 caused by the deviation between the ratio crown R _c4 obtained from the actually measured plate profile (plate crown) C _r4 on the exit side of the fourth stand F4 and the target ratio crown R _c4 ^Aim on the exit side of the same stand. Downstream stand F
This is a method of controlling so as to cancel the plate crown error generated in 5 to F7. Downstream side stands F5 to F7 in this case
The change amount of the crown ratio for each can be obtained by the above equation (9).

The second 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),
Further, the ratio crown change amount for each of the stands F5 to F7 can be obtained by the above equation (10).

Rear stand with thin strip thickness
However, since the shape is likely to be disordered as described above, the i-th
Ratio Crown R_ciThe changeable amount of
Kick Therefore, the above ratio calculated by the following equation (11)
Rate crown changeable amount ΔR _ciWithin the restrictions determined by
It is important to consider whether to approach the target
Is important for

ΔR _ci = f ₆ (h, b, D) (11)

In the first method, the changeable amount of the ratio crown in the downstream stand cannot be taken into consideration, but in the second method, this can be taken into consideration. Therefore, the second method Is more advantageous than the first method.

Further, in this embodiment, even after the tip of the strip has passed 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
In order to clarify the effect of the control method using the actually measured plate profile by A, the result of actual plate profile control will be described.

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 meters are installed are changed so that the plate is 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.

[0101]

[Table 1]

[0102]

[Table 2]

FIG. 4 shows the error between the measured plate profile and the target value on the exit side of the final stand obtained when the plate profile control is carried out as the plate profile control accuracy (μm).
) Is a graph showing the correlation between this and the passing plate thickness (mm) between the stands where the plate profile meter is installed.

As is clear from FIG. 4, when the passing plate thickness 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 when the plate thickness is 2 mm or more is because the ratio crown change limit determined by the shape limit is rapidly increased as shown in FIG. If it exceeds, it will decrease as shown in FIG.
It is understood that, as shown in, the genetic coefficient β _i becomes smaller and the number of rolling times until reaching the final product increases.

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
Since the second plate profile meter 20B is installed between the fifth stands that are continuous between the fourth stands, when performing the above-described plate profile control based on the measured plate profile obtained by the first plate profile meter 20A. It is possible to control the fifth stand by using the measured plate crown C _r5 on the exit side of the fifth stand F5 obtained by the second plate profile meter 20B.

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.

In this embodiment, as described above, the first plate profile meter 20A measures the plate crown C _r4 on the _output side of the fourth stand F4, and the second plate profile meter 20B measures the _output side of the fifth stand F5. Plate crown C _r5 of
Further, the roll profile meter 22 _measures the roll profile C _mr5 of the work roll of the stand F5, and the load meter 12B measures the rolling load P ₅ of the stand F5.
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
By obtaining the mechanical crown transfer rate α _{i of} the equation and the genetic coefficient β _{i of the} equation (7) and changing the learning correction coefficient (regression coefficient K _ch , shape change coefficient ξ) in these calculation model equations, It is possible to improve the accuracy of the initial setting of the rolled material.

This will be described in more detail. As in the present embodiment, an arrangement in which plate profile meters 20A, 20B are installed between two stands sandwiching one rolling stand equipped with a roll profile meter is adopted. Of the target stand F _i (i = 4) exit side plate crown C _ri , the preceding stand stand exit side plate crown C _ri-1 , and the same target stand F _i required for the crown calculation by the equation (1). Since the sum (C _mRhi + C _mRwi ) of the crown due to the thermal expansion of the roll and the crown due to the roll wear can be measured, the only error factors are the transfer rate α _i and the genetic coefficient β _i . Therefore, these transcription rates α can be easily
It is possible to optimize _i and the genetic coefficient β _i . The transfer rate α _i and the genetic coefficient β _i change depending on the temperature distribution in the width direction of the material, the material characteristics, etc., and the change due to the difference in stand is small. Applying this to other stands does not cause any significant problems.

Further, in this embodiment, in the first plate profile meter 20A and the second plate profile meter 20B, the central plate thickness h ₄ on the exit side of the fourth stand F4 and the central plate plate on the exit side of the fifth stand F5 are used. While measuring the thickness h ₅ ,
Since the plate thickness gauge 24 can measure the central plate thickness h ₆ on the exit side of the sixth stand F6, these measured plate thicknesses are input to the plate thickness control computing device 18, and the computing device 1
In step 8, these measured values are compared with the preset target stand-to-stand target plate thickness, and the plate thickness control device 1
By changing the control amount for No. 4, it is possible to control the plate thickness with high accuracy.

Further, as described above, by installing the first profile meter 20A between the third and fourth stands counted from the downstream side, the strip thickness difference in the width direction of the strip passing through the measurement position can be measured. Can also be detected. Since the plate profile can be still corrected between the fourth stands, when 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 feed-forward 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 the final product of the strip S from meandering. By improving the meandering of the strip S in this way, it is possible to reduce the troubles of passing through such as narrowing down when the leading end and the rear end pass through.

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 above in detail, according to this embodiment, 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 above, by performing feedback control on the rolling stand on the upstream side of the installation position of the plate profile meter 20A, the strip passing between the stands can be matched with the target plate profile at that position, By performing feedforward control to the downstream stand, the plate profile meter 20
Even if there is a deviation between the measurement result of A and the target value, the product plate profile on the delivery side of the final stand can be matched to the target value. In fact, in the conventional method, the plate profile control accuracy error of 30 μm could be reduced to 10 μm or less.

Further, according to the above feedback control, as compared with the conventional case where the strip profile meter is installed at or near the exit side of the tandem rolling mill, the material required before the feedback control is applied The length can be greatly reduced. By the way, when converting from the 4th stand outlet side to the 7th stand outlet side to strip length,
For example, it will be about 20 m.

Further, according to the feedforward control described above, 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 significantly controlled as compared with the conventional predictive control. It is possible to improve accuracy.

Further, according to this embodiment, the plate profile between the stands, which was unknown in the past, was found, and the plate profile meter was installed on the rolling stand sandwiched between two continuous stands. Since the roll profile for 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 roll profile on the inlet and outlet sides of the rolling stand.

Therefore, it is possible to quantitatively and directly grasp the difference 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.

The present invention has been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above embodiment, the finish rolling mill has 7
Although the thing which consists of a stand was demonstrated, it is not limited to this.

Further, in the finish rolling mill consisting of the 7 stands, the first plate profile meter 20A has a passing plate thickness of 4 mm.
It was installed between the 4th stands of less than 2mm,
It is not limited to this.

Further, the installation positions and the numbers of the plate profile meter, the roll profile meter and the 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.

[0125]

As described above, according to the present invention, the plate profile on the delivery side of the final stand, including the tip portion, can be hit to the target value with high accuracy without causing a defective shape of the strip. It is possible to control the plate profile with high responsiveness.

[Brief description of 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 the genetic coefficient and the plate thickness.

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

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

[Explanation of symbols]

 10 ... Plate Profile Control Device 12 ... Load Meter 14 ... Plate Thickness Control Device 16 ... Plate Profile Control Calculation Device 18 ... Plate Thickness Control Calculation Device 20 ... Plate Profile Meter 22 ... Roll Profile Meter 24 ... Plate Thickness Meter 26 ... Flatness 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 (4)

[Claims] 1. A rolling control method in a hot strip finishing rolling mill comprising a plurality of rolling stands arranged in series, wherein a plate profile meter installed between the stands is used to measure a strip profile of a strip passing between the stands, A rolling control method in a hot strip finishing rolling mill, characterized in that the rolling stand on the downstream side between the stands for the sheet profile meter is controlled based on the measured sheet profile, and the sheet profile at the exit side of the final stand is made to match a target value. . 2. The deviation according to claim 1, between a measured plate profile obtained between the stands for installing the plate profile meter and a target plate profile obtained beforehand between the stands, and the downstream based on the deviation. A rolling control method in a hot strip finishing rolling mill, characterized in that a rolling stand on the side of the rolling mill is controlled. 3. The plate profile on the output side of the final stand is predicted based on the actually measured plate profiles obtained between the plate profile meter installation stands, and the predicted plate profile and the target plate on the output side of the final stand are predicted. A rolling control method in a hot strip finish rolling mill, characterized in that the rolling stand on the downstream side is controlled so as to reduce an error from a profile. 4. The deviation according to claim 1, wherein 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 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.