JP2000288615A - Flatness control device during reverse rolling and control method therefor - Google Patents

Abstract

(57) [Problem] To provide a flatness control device at the time of reverse rolling and a control method thereof, which can accurately estimate the wear and heat crown of a rolling roll and reflect it in a plate crown prediction model. Kind Code: A1 A sheet crown measuring device for measuring a sheet crown of a rolled material at least once in a rolling pass, a roll profile measuring device for measuring a profile of a rolling roll, and measurement data and rolling result data. Model error calculating device 8 for estimating a roll profile prediction model error and a sheet crown prediction model error, based on these estimated values, a rolling mill for preventing flatness failure in rolling after the next pass A device provided with a device 9 for calculating a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for controlling a crown and flatness when a rolled material such as a thick plate is rolled by reverse rolling.

[0002]

2. Description of the Related Art Generally, in plate rolling, flatness defects are likely to occur in the second half pass in which the plate thickness is reduced. Therefore, a rolling process having a predetermined plate thickness or less is called a shape control pass, and flatness defects do not occur. Rolling is performed by setting such a rolling schedule. At this time, in order to control the occurrence of poor flatness, it is necessary to accurately form a sheet crown (thickness distribution in the width direction of the steel sheet).

However, there are various errors between the previously calculated rolling schedule and actual rolling, such as errors in the prediction model of the sheet crown, or prediction errors in the roll profile caused by heat crown or roll wear. Actually, the crown of the rolled material is not as expected, and this may cause poor flatness.

[0004] In particular, the roll profile is difficult to predict due to the combination of heat crown and wear.
Conventionally, a method of calculating a prediction error based on shape measurement information and controlling a work roll bending force (Japanese Patent Laid-Open No.
JP-A-32412, hereinafter referred to as first prior art), and a method of calculating a roll wear amount and determining a work roll bending force according to the amount (JP-A-3-13813, hereinafter referred to as second prior art). Etc.) are known.

[0005]

However, the above-mentioned prior art has the following problems.

In the second prior art, a model error of roll wear is learned based on a measured value of a sheet crown, but the influence of a heat crown (thermal expansion) is not considered.

Further, in the first prior art, an attempt is made to estimate a prediction error of a sheet crown and a roll profile on the basis of shape measurement information, but this has the following problems. That is, the shape measurement information can be used when the plate shape is disturbed, but cannot be used in a range where the shape is not disturbed. The shape disturbance is caused by a change in the sheet crown ratio represented by the equation (1) before and after the rolling pass.

Sheet crown ratio = Cri / Hi (1) Cri: Outgoing sheet crown at i-pass Hi: Outgoing sheet thickness at i-pass If the sheet crown ratio is constant before and after the rolling pass, the shape of the sheet is disturbed. However, when a plate having good flatness is obtained, but the plate crown ratio is not constant, an elongation difference Δγ occurs at each position in the width direction expressed by the equation (2), and the elongation difference Δγ Then, for example, the ear wave state (Δγ) shown in FIG.
>0; the end of the plate is extended from the center of the plate) or (b)
The flatness defect occurs as shown in the middle elongation state (Δγ <0; the center part of the plate is longer than the end of the plate). The steepness λ shown in FIG. 4C is used as an index representing the flatness. Assuming that the plate wave is a sine wave, the steepness λ is equal to the elongation difference Δ
It is expressed by equation (3) using γ.

Δγ = Cri / Hi−Cri−1 / Hi−1 (2) Cri−1: Crown on the exit side in the i−1 pass Hi−1: Thickness on the exit side in the i−1 pass λ = 2 / π√ (Δγ) (3) In the above-mentioned conventional technology, the flatness is measured in the middle of the rolling pass,
The main purpose is to estimate the error of the sheet crown model by estimating the sheet crown using the relation of the equation (2) and the like, and making this equal to the actually measured sheet crown.

However, it is generally known that there is a range in which the plate does not buckle even if the elongation difference Δγ occurs in the equation (2), and consequently the shape is not disordered. Therefore, there is a problem that when the shape is not disturbed, the error estimation of the sheet crown model cannot be performed.

On the other hand, the roll profile is directly measured,
Although it is conceivable that the measured roll profile is directly reflected in the sheet crown model, it takes several tens of seconds to measure the roll profile, and there has been a problem that the rolling efficiency is significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to accurately estimate the wear of a rolling roll and a heat crown, and to control the flatness at the time of reverse rolling which can be reflected in a sheet crown prediction model. It is an object to provide an apparatus and a control method thereof.

[0013]

According to a first aspect of the present invention, there is provided a system for performing reverse rolling of a steel sheet by a rolling mill, comprising: a strip crown on the delivery side of the rolling mill; Measuring means for measuring the roll profile, predictive calculating means for predicting and calculating the sheet crown and roll profile based on the sheet crown and roll profile measured by the measuring means, and predictive calculating value calculated by the predicting calculating means And a flatness control means for controlling the flatness of the steel plate on the rolling mill output side based on the flatness control device.

According to a second aspect of the present invention, there is provided a flatness control device for reverse rolling used when a rolled material is rolled by reverse rolling by a rolling mill, wherein the front and rear surfaces of the rolling mill are provided. A sheet crown measuring device for measuring a sheet crown of a rolled material at least once during a rolling pass at at least one position, a roll profile measuring device for measuring a profile of the rolling roll, the sheet crown measuring device, and the roll From the measurement data of the profile measuring device and the rolling performance data, a roll profile prediction model error, a plate crown prediction model error, and a model error calculation device for estimating the plate crown prediction model error, and based on these estimated values, , Rolling mill set values to prevent poor flatness in rolling after the next pass A device for computing a flatness control device during reverse rolling equipped with.

In order to achieve the above object, the invention according to claim 3 is characterized in that the model error calculating device calculates a predicted model error of a sheet crown model, the measured value from the roll profile measuring device, 3. The flatness control device during reverse rolling according to claim 2, wherein the flatness control device is used by switching between a roll profile calculation value.

According to a fourth aspect of the present invention, there is provided a system for performing reverse rolling of a steel plate by a rolling mill, wherein a roll crown of the rolling mill and a strip crown on an outlet side of the rolling mill are measured. A flatness control method for reverse rolling in which the plate crown and roll profile are predicted and calculated based on the measured plate crown and roll profile, and the flatness of the steel sheet on the rolling mill exit side is controlled based on the predicted calculation result. It is.

According to a fifth aspect of the present invention, there is provided a method for controlling flatness of a sheet crown at the time of reverse rolling, which is used when a rolled material is rolled by reverse rolling by a rolling mill. A first procedure of measuring the strip crown of the rolled material at least once in a rolling pass at at least one position on the rear surface, a second procedure of measuring a profile of a rolling roll between the materials or between the passes, and these measurements. Roll profile prediction error from the data and the rolling performance data, a third procedure for estimating the sheet crown prediction error, and, based on the estimated values, set the rolling mill settings so that the sheet crown and flatness in rolling after the next pass are as intended. It is a flatness control method at the time of reverse rolling provided with the fourth procedure to determine.

According to any one of the first to fifth aspects of the present invention, it is possible to accurately predict a roll profile that changes during rolling and accurately predict a sheet crown. As a result, the accuracy of the sheet crown and flatness control can be greatly improved, so that a sheet thickness defect due to a prediction error of the sheet crown can be prevented, and the flatness defect can be reduced.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. First, a schematic configuration will be described with reference to FIG. The plate flatness control device for reverse rolling used when the rolled material 2 is rolled by the rolling mill 1 by reverse rolling is generally constituted by the following device.

That is, at least one of the front surface and the rear surface of the rolling mill 1
A sheet crown meter 4 for measuring the thickness of the rolled material 2, a sheet crown measuring device 5 for changing the thickness measured by the sheet crown meter 4 to a sheet crown measurement value, and a roll for measuring the distance to the work roll 3 From the profile meter 6, a roll profile measuring device 7 for calculating a roll profile based on the distance measured by the roll profile meter 6, a roll profile measuring device 5 and a roll profile measuring device Error calculator 8 for estimating the prediction model error of the sheet crown, the sheet crown prediction model error, and the sheet crown prediction model error
And a rolling mill setting calculating device 9 for calculating a rolling mill setting value for preventing a flatness defect in rolling after the next pass based on these estimated values, and providing the calculated rolling mill setting value to a rolling mill setting device 10. Things.

Here, the details of the model error calculating device 8 and the rolling mill setting calculating device 9 will be described. The model error calculation device 8 has the following functional units (steps S1 to S4), and calculates the roll profile model correction amount and the sheet crown model correction amount of the work roll 3 at appropriate times.

In step 1 (hereinafter referred to as S1), the model error calculating device 8 calculates rolling results such as rolling load and plate length.
Then, a roll profile correction amount to be described later is input, and a roll profile calculation value is calculated by the following equations (5) and (7). In S2, the measured value and the calculated value of the roll profile are compared, and the correction amount of the roll profile model is calculated by using a method shown in Expression (10) described later.
In step S3, the sheet crown measurement value and the sheet crown calculation value are input, and the sheet crown model error correction amount is calculated by the following equation (8). In S4, the roll profile calculated value obtained in S1 or the roll profile measured value measured by the roll profile measuring device 7 is input through the switch 20, and the calculated crown value of the sheet is calculated by the following equation (4).

The switching between the roll profile calculation value and the roll profile measurement value by the switch 20 is based on the following reason. The model error calculating device 8 is for measuring the roll profile and accurately estimating the model error of the sheet crown, but it takes time to measure the roll profile. For this reason, the measurement of the roll profile is performed once for some of the rolled materials 2.

However, the measurement of the sheet crown and the calculation of the model error of the sheet crown are performed for each rolled material. At this time, when the roll profile is also measured, the result is used as the Cwi in the equation (4) for the sheet crown calculation, but is calculated by the equation (7) in the rolling without measuring the roll profile. The calculated value of the role profile
It is used for the calculation of the plate crown in S4.

The rolling mill setting calculation device 9 has the following functional means (S5 to S7), and the model error calculation device 8
And the roll profile model correction amount and the plate crown model correction amount are input from the above, and a rolling mill set value for preventing a flatness defect in rolling after the next pass is calculated.

In step S5, the sheet crown model correction amount obtained in step S3, rolling mill setting parameters to be described later, and a roll profile calculation value to be described later are input, and the following equation (6) or
The plate crown calculation value is calculated by equation (9).

In step S6, the roll profile model correction amount obtained in step S2 and the rolling mill setting parameters to be described later are input, and the roll profile calculation value is calculated by equation (7).
In step S7, the plate crown calculation value obtained in step S5 is input, and the above-described equations (1), (2), (3), and (4) described later are used.
The rolling mill setting parameters are calculated using an equation or the like.

With the above configuration, the following operation and effect can be obtained. During rolling, the sheet crown is measured at least once by the sheet crown meter 4 and the sheet crown measuring device 5, and the prediction error of the sheet crown is calculated by S2 of the model error calculation device 8, and the prediction error is calculated from the next pass. Reflect on rolling. However, the sheet crown prediction error includes the roll profile prediction error.

Therefore, by appropriately measuring the roll profile using the roll profile meter 6 and the roll profile measuring device 7, the roll crown prediction error can be calculated using the actually measured roll profile at the time of roll profile measurement. As a result, the influence of the roll profile prediction error can be excluded from the strip crown prediction error, and the strip crown prediction error can be accurately estimated.

Further, by calculating the roll profile prediction error using the roll profile actually measured at the time of the roll profile measurement, the roll profile and the sheet crown are calculated using the roll profile prediction error until the next roll profile measurement. It is possible to estimate the plate crown accurately by performing the prediction calculation of
A steel plate having a good plate crown and flatness can be manufactured.

In FIG. 1, a rolled material 2 is reverse-rolled in a rolling mill 1 in a plurality of passes. The rolling mill 1 is provided with a bender (not shown) for the work roll 3 as an actuator for changing the sheet crown. The plate crown of the rolled material 2 after each pass is expressed by equation (4).

Cri = f (Pi, Fbi) + β · Cwi (4) Cri: Outboard crown at i-pass Pi: Rolling load Fbi: Work roll bending force Cwi: Work roll profile β: Work roll profile Cwi Influence on Crown f (Pi, Fbi): Strip Crown due to Rolling Load Pi and Work Roll Bending Force Fbi On the other hand, the flatness of the rolled material 2 is expressed by the above-described equations (2) and (3). Therefore, in a certain rolling pass, the difference between the elongation percentage obtained by the equation (2) and the strip crown after the rolling pass may be set to a value within a range in which the shape is not disturbed with respect to the strip crown before the rolling pass.

By determining the work roll bending force for realizing the strip crown after the rolling pass determined in this way by using the equation (4), a strip having good flatness can be obtained.

In equation (4), f (P, Fbi) is a term mainly related to the mechanical deformation of the roll, and is represented by a mathematical model. Work roll profile Cwi is (5)
As in the formula, roll wear, heat crown (thermal expansion)
It is represented by

Cwi = Cw0-Cww + Cwh (5) Cw0: Work roll initial crown Cww: Wear Cwh: Heat crown Wear Cww and heat crown Cwh are each represented by a mathematical model. Here, when the equation (4) is rewritten to include the error of each model, the equation (6) is obtained.

Cri = f (Pi, Fbi) + δ1 + β · Cwi (6) δ1: Model error of mechanical deformation of roll Further, equation (5) becomes equation (7).

Cwi = Cw0− (Cww + δ2) + (Cwh + δ3) (5) δ2: Model error of roll wear δ3: Model error of roll heat crown Model errors δ1 to δ1 in equations (6) and (7) By accurately estimating δ3, it is possible to accurately estimate the sheet crown, and it is possible to obtain a rolled material having good flatness.

Here, the procedure for estimating the model errors δ1 to δ3 will be described.

In FIG. 1, a roll profile measuring device 7 measures the roll profile of the work roll 3 at appropriate times. The model error calculation device 8 executes step 1 (hereinafter S
1), a roll profile calculation value is calculated using rolling results such as a rolling load and a plate length. In S2, the measured value and the calculated value of the roll profile are compared to calculate a roll profile model error.

On the other hand, at least once during the rolling pass, the sheet crown measuring device 5 measures the sheet crown of the rolled material by the sheet crown meter 4. In step S4, the model error calculating device 8 applies the rolling results such as the rolling load and the work roll bending force to the equations (4) and (6) to calculate the crown value of the sheet.

At this time, if the roll profile is measured by the roll profile measuring device 7 immediately after the rolling pass, an actually measured value is used as the roll profile. If the roll profile measuring device 7 does not measure the roll profile, the roll profile model error calculated in S2 is applied to the equation (7) to estimate the roll profile in S1.

In step S3, the measured value of the crown and the calculated value of the crown are compared to calculate a crown error.

From the next pass onward, the rolling mill setting calculation unit 9 calculates the roll crown by the roll profile calculation S6 and the roll crown calculation S5 using the model prediction error obtained above, and first uses the result to obtain the roll crown. As described above, the work roll bending force is determined by equation (6) in order to achieve a plate crown with good flatness.

Then, by finally setting the rolling mill 1 by the rolling mill setting device 10, a target rolled material 2 can be obtained.

The plate crown model error in S3 can be obtained, for example, as in equation (8).

Δ1 = Cra−Crc (8) Crc: Plate Crown Calculated by Model Cra: Plate Crown Measured by Plate Crown Measuring Apparatus 5 At this time, the equation for estimating the plate crown calculated in step 5 is as follows: Becomes

Cr = Crc + δ1 (9) Needless to say, a method of sequentially identifying various parameters in the model formula using a plurality of measurement results can be adopted.

The method of calculating the roll profile model error in S2 is not unique, but if, for example, the roll profile can measure n points in the roll body length direction, the error between the two models of wear and heat crown is (10) )
It can be obtained as δ2, δ3 that minimizes the evaluation function J of the equation.

[0049] _{J = Σ j {Cwa j -} [Cw0 j - (Cww j + δ2) + (Cwh j + δ3)]} 2 ... (10) Cwa j: roll profile measured by a roll profile measuring apparatus 7 subscript j: Roll body length direction position (j = 1 to n) The frequency at which the roll profile is measured can be determined, for example, as follows.

FIG. 2 is an example showing how the calculated value and the actual value of the heat crown change depending on the number of rolls. As shown in this figure, the calculated value can be made closer to the actual value by measuring the roll profile and correcting the model error. The same is true for wear.

Accordingly, the model prediction error of the sheet crown becomes minimum when the error is corrected by the roll profile measurement, and thereafter the error tends to increase. For this reason, the tendency of the model prediction error of the sheet crown may be monitored, and the roll profile may be measured when a certain appropriate threshold is exceeded. FIG. 3 shows this state.

<Modification> In the present embodiment, work roll bending is used as a means for changing the sheet crown. However, when other means for changing the sheet crown, for example, a method of crossing a roll, is used. It goes without saying that the present invention is applicable.

[0053]

According to the present invention, it is possible to accurately predict a roll profile that changes during rolling and to accurately predict a sheet crown, thereby greatly improving the precision of sheet crown and flatness control. To improve
It is possible to provide a flatness control device and a control method thereof during reverse rolling, which can prevent a thickness defect due to a plate crown prediction error and can also reduce a flatness defect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an apparatus according to an embodiment of the present invention and a flow of an arithmetic unit.

FIG. 2 is a graph showing an example of a transition of a calculated value of a heat crown and a result.

FIG. 3 is a graph showing an example of transition of a plate crown model error.

FIG. 4 is a diagram showing an example of a rolled material having poor flatness.

[Explanation of symbols]

 1. Rolling machine 2. Rolled material 3. Work roll 4. Sheet crown meter 6. Roll profile meter. 7 Roll profile measuring device 8 Model error calculating device 9 Rolling machine setting calculating device 10 Rolling machine setting device 20 Switching device

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[Procedure amendment]

[Submission date] May 24, 2000 (2005.2.
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

According to a second aspect of the present invention, there is provided a flatness control device for reverse rolling used when a rolled material is rolled by reverse rolling by a rolling mill, wherein the front and rear surfaces of the rolling mill are provided. A sheet crown measuring device for measuring a sheet crown of a rolled material at least once during a rolling pass at at least one position, a roll profile measuring device for measuring a profile of the rolling roll, the sheet crown measuring device, and the roll A model error calculating device for estimating a roll profile prediction model error and a sheet crown prediction model error from the measurement data of the profile measuring device and the actual rolling data, and a rolling process for the rolling after the next pass based on these estimated values. A device for calculating a rolling mill set value for preventing poor flatness in the A flatness control device when reverse rolling.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

Cwi = Cw0− (Cww + δ2) + (Cwh + δ3) (7) δ2: Model error of roll wear δ3: Model error of roll heat crown Model errors δ1 to δ1 in equations (6) and (7) By accurately estimating δ3, it is possible to accurately estimate the sheet crown, and it is possible to obtain a rolled material having good flatness.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05B 13/04 B21B 37/00 116M (72) Inventor Toshitaka Tanaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Inventor Masato Uchio 1-2-2 Marunouchi, Chiyoda-ku, Tokyo F-term inside Nippon Kokan Co., Ltd. 4E024 AA02 AA03 DD01 EE02 5H004 GB03 HA06 HA20 HB06 HB07 JA22 JA30 JB08 JB09 JB30 KC08 KC24 KC28 KC35 KC43 KD62 LA11 LA18 9A001 KK32 KK54 KZ34

Claims (5)

[Claims] In a system for performing reverse rolling of a steel sheet by a rolling mill, a measuring means for measuring a sheet crown on an outlet side of the rolling mill and a roll profile of the rolling mill; and a sheet crown measured by the measuring means, Prediction calculating means for predicting and calculating the sheet crown and roll profile based on the roll profile; and flatness controlling means for controlling flatness of the steel sheet on the rolling mill exit side based on the predicted calculation value calculated by the prediction calculating means. A flatness control device at the time of reverse rolling, comprising: 2. A flatness control device for reverse rolling used when a rolled material is reversely rolled by a rolling mill, wherein at least one of a front surface and a rear surface of the rolling mill, a rolled material is passed through a rolling pass. A sheet crown measuring device that measures the sheet crown at least once; a roll profile measuring device that measures the profile of the rolling roll; and a measurement data and a rolling result data of the sheet crown measuring device and the roll profile measuring device. A model error calculating device for estimating a roll profile prediction model error, a sheet crown prediction model error, and a sheet crown prediction model error, and based on these estimated values, prevents poor flatness in rolling after the next pass. And a device for calculating a rolling mill set value for Flatness control device when Bath rolling. 3. The apparatus according to claim 2, wherein the model error calculating device switches and uses the measured value from the roll profile measuring device and the roll profile calculated value when calculating the prediction model error of the sheet crown model. 3. The flatness control device at the time of reverse rolling according to claim 2. 4. A system for performing reverse rolling of a steel sheet by a rolling mill, comprising: measuring a sheet crown on an outlet side of the rolling mill and a roll profile of the rolling mill; A flatness control method at the time of reverse rolling, wherein a flatness of a steel sheet on the exit side of the rolling mill is controlled based on a prediction calculation of a plate crown and a roll profile, and based on the prediction calculation result. 5. A method for controlling flatness of a sheet crown at the time of reverse rolling, which is used when a rolled material is rolled by a reverse rolling by a rolling mill, wherein at least one of a front surface and a rear surface of the rolling machine is rolled in a rolling pass. At least one sheet crown of material
A first procedure for measuring the number of times, a second procedure for measuring the profile of the rolling roll between the materials or between passes, and a third procedure for estimating a roll profile prediction error and a sheet crown prediction error from these measurement data and rolling performance data. A flatness control method for reverse rolling, comprising: a procedure; and a fourth procedure for determining a rolling mill setting for achieving a target sheet crown and flatness in rolling after the next pass based on the estimated value.