JP2000135506A - Method of rolling plate with reversible rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately correct plate crown and plate shape by measuring the plate crown before the i-th pass and plate crown after the i-th pass and flatness to collect rolling data, calculating the plate crown after the pass with a plate crown model, calculating roll profile so as to agree with the measured values, and also calculating in the same way for flatness. SOLUTION: From the measured value of the plate crown before and after the i-th pass, the flatness after the i-th pass is calculated with a flatness calculation model, and the difference of the flatness after the i-th pass from the measured value is calculated. At least in one pass of passes after the (i+1)-th pass and passes of the following plate, pass schedule setting calculation is made using the roll profile, and work roll bending force setting calculation to correct error of flatness is made. The rolling is done using the resulting pass schedule and work roll bending force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pass schedule calculation which satisfies a predetermined plate crown and a predetermined plate shape (hereinafter referred to simply as "plate shape") when a plate material is rolled to a predetermined thickness by a reversible rolling mill. And a rolling method using a work roll bending force setting calculation.

[0002]

2. Description of the Related Art When rolling a sheet material, it is necessary not only to achieve a target sheet thickness but also to obtain a target sheet crown and sheet shape. Roll control based on given rolling conditions to control the sheet crown and sheet shape,
The pass schedule must be calculated in consideration of the deformation resistance of the rolled material, the elastic deformation of the rolling mill including the rolls, and the roll profile (diameter distribution of the work roll in the axial direction). That is, a mathematical model for calculating the plate crown and the plate shape based on these rolling parameters is required.

With respect to the elastic deformation of a roll during rolling, a roll load, deformation resistance of a rolled material, elastic deformation of a rolling mill, Techniques for calculating from roll bending force and the like have been reported in literature (for example, “Theory and Practice of Sheet Rolling”, edited by The Iron and Steel Institute of Japan, 1984, pp. 89-101).

On the other hand, with respect to the roll profile, various attempts have been made to predict the plate crown and plate shape by predicting the work roll profile model, that is, the contribution of the roll wear and the contribution of the heat crown due to the heat up of the roll. I have.

For example, Japanese Patent Application Laid-Open No. 56-17161 discloses that a heat crown bulge width and its amount, and a wear width and its amount due to thermal expansion of a roll are calculated based on a rolling history, and the bulge width obtained by the calculation is calculated. And the wear width and the sheet width of the sheet to be rolled next are compared to determine the heat crown and the amount of wear acting on the sheet, the heat crown and the amount of wear are converted to equivalent sheet crowns, and the sheet after rolling is obtained. There is disclosed a technique for calculating a reduction amount such that a shape or a crown of a sheet becomes a desired state.

Japanese Patent Application Laid-Open No. 63-25858 discloses an actual measurement value of one or both of a sheet crown and a sheet shape of a preceding material after rolling, and using the rolling conditions of the preceding material, a sheet crown is obtained. Either or both of the sheet shape and the plate shape are obtained by calculation, and the difference between the actually measured value and the calculated value is caused by the roll profile estimation error.The roll profile estimation error is calculated, learned, and A technique used for setting calculation is disclosed.

Further, various attempts have been made on a rolling method for correcting an error of a mathematical model necessary for calculating a pass schedule for obtaining a desired sheet crown and sheet shape by using work roll bending (hereinafter referred to as WR bending). I have.

For example, Japanese Patent Application Laid-Open No. 3-32412 discloses that a flatness and a sheet crown are measured at least once during a rolling pass, and a rolling load prediction error, a roll profile and a roll profile are obtained from the measured data and the actual rolling data. A technique of estimating a prediction error of a sheet crown and a prediction model error of a sheet crown, determining a WR bending force for preventing a flatness defect after the next pass, and performing rolling is disclosed.

[0009]

SUMMARY OF THE INVENTION The above-mentioned JP-A-56-17
No. 161 discloses a rolling history, that is,
It is based on a method of estimating the history of the roll heat-up amount and the wear amount due to the past rolled material by a roll profile model formula. However, the heat crown changes every moment due to the roll cooling method, the change in the width of the sheet material, the change in the rolling pitch, and the like, and the roll wear also changes according to the temperature, rolling load, surface condition, and the like of the sheet material. Therefore, accurate formulation of the roll profile is extremely difficult.

[0010] In addition, the technique disclosed in this publication only calculates the roll profile unilaterally, and has no means for evaluating and correcting whether the calculated roll profile is appropriate. , It is difficult to accurately predict the plate crown and the plate shape.

The technique disclosed in Japanese Patent Application Laid-Open No. 63-25845 discloses that a difference between an actually measured value and a calculated value of one or both of a rolled crown and a strip shape is attributed to a roll profile. Is used to estimate the roll profile prediction error by going back several passes or tens of passes (rolling passes by multiple stands in a tandem type rolling mill). However, calculation errors in the backward calculation for each pass are accumulated. There is a problem that it is easy. In particular, the change of the heat crown changes every moment even during the same rolled material, and the method of obtaining the prediction error of the roll profile from the sheet crown error measured after multi-pass rolling cannot obtain sufficient accuracy. is there.

Further, in a reversible rolling mill for a thick plate,
When performing tentative rolling in the first few passes, the rolling width is 1
It is particularly difficult to model the heat crown because it changes greatly for each pass.

[0013] On the other hand, even if the roll profile, which is the above problem, can be accurately predicted, it is difficult to always maintain the flatness, which finally becomes a problem. The shape of the steel sheet is generated because the longitudinal elongation due to rolling is uneven at each position of the sheet width, and the distribution of this longitudinal elongation is represented by the distribution of thickness strain before and after the rolling pass, that is, It is known that there is a correlation with a change in the sheet crown ratio.

[0014]

(Equation 1)

Here, h _c is the plate thickness at the center position of the plate width,
h _e represents the thickness of a plate width edge, "1" second digit of the suffix "2" before each rolling pass, meaning after.

In general, a pass schedule calculation is performed so that the above-mentioned change in plate crown ratio Δγ becomes Δγ = 0 so as not to cause a shape defect.

However, a shape defect is expressed as a large shape defect of 1 to 2% at a steepness λ to be described later due to a slight Δγ, so that the WR profile shown above is accurately calculated, and the path schedule calculation is performed. Even if it is performed, shape failure occurs due to unpredictable factors such as the temperature distribution in the width direction of the steel sheet and the distribution of the friction coefficient.

The relationship between the shape of the steel sheet and the above-mentioned sheet crown ratio has been studied from various directions, and several relational expressions for connecting them have been proposed. According to these studies, the relationship between the sheet crown ratio change Δγ and the steepness λ can be changed variously according to various conditions such as sheet width, sheet thickness, reduction ratio, steel type, finishing temperature, and work roll diameter. This suggests that it is difficult to accurately determine the change in the sheet crown ratio from the measured flatness.

As a method for preventing this, Japanese Patent Laid-Open No.
The method disclosed in Japanese Patent No. 32412 discloses a procedure for obtaining a WR profile, a rolling load, and a prediction error of a sheet crown from the measured values of the flatness and the sheet crown. (Π / 2 · λ) ² is uniquely determined. However, as described above, Δγ and λ
Considering that the relationship varies with various factors,
This method generates a large error in the process of estimating the prediction error, and also calculates the prediction error of the WR profile and the sheet crown simultaneously from the simultaneous equations based on the steepness, the sheet crown, and the actual rolling data. Since the prediction error calculation includes the prediction error associated with the backward calculation of each path described above, the prediction error of the WR profile cannot be accurately obtained. Furthermore, since these relationships are solved by simultaneous equations, there is a problem that the prediction error of the plate crown cannot be obtained accurately, and the error of the mathematical model cannot be predicted accurately, and the flatness cannot be accurately calculated. It is difficult to fix well.

In view of these problems of the prior art, an object of the present invention is to calculate a roll profile that changes every moment with high accuracy and use it for pass schedule calculation.
An object of the present invention is to provide a means for accurately estimating an error of a flatness calculation model and accurately correcting a plate crown and a plate shape generated by a factor which is difficult to predict.

[0021]

SUMMARY OF THE INVENTION When rolling to a predetermined thickness by a reversible rolling mill, the present inventor has a pass schedule satisfying a predetermined plate crown and a predetermined plate shape (plate flat shape, hereinafter simply referred to as plate shape). As a result of conducting various experiments and studies on the rolling method using the calculation and the WR bending, the following findings were obtained.

(A) When a roll profile is obtained from the result of rolling the preceding material and this roll profile is used for calculating the pass schedule of the succeeding plate, the initial plate crown and plate shape can be secured in the first half pass of the succeeding plate. The error is large near the last pass. This is considered to be because the roll profile changes every moment during rolling, and the error of the roll profile calculation model near the final pass increases.

(B) When the width of the subsequent plate material largely changes, the plate crown and the plate shape are easily disturbed. This is considered because the error of the roll profile calculation model becomes large.

(C) The last two or three passes greatly affect the control of the plate crown and the plate shape. It is necessary to calculate the roll profile at this stage particularly accurately.

(D) The distribution of elastic deformation in the roll width direction is obtained from rolling data (rolling load, rolling position, roll speed, WR bending force, sheet temperature and material, sheet thickness before and after rolling, sheet width, etc.). . Therefore, the roll profile can be determined by actually measuring the sheet crown before and after a certain rolling pass, obtaining the roll surface displacement and the roll load distribution during rolling, and subtracting the elastic deformation of the roll during rolling. This calculation solves a multiple simultaneous equation, but a solution can be obtained by iterative calculation.

(E) Even if the roll profile is accurately determined by the above-described method and the pass schedule is calculated, the pass schedule is affected by factors that are difficult to predict, such as the temperature distribution in the plate and the friction coefficient distribution between the WR and the material. An error may occur in the calculation, and a desired plate crown and flatness may not be ensured.

(F) The difficult-to-predict error can be estimated from the difference between the measured flatness value and the calculated flatness value obtained by using the plate crown value actually measured or calculated by the flatness calculation model.

(G) A desired plate crown and flatness can be obtained by obtaining a WR bending force for correcting the estimated prediction error and adding it to the pass schedule calculation.

Based on the above findings, the gist of the present invention resides in the following (1) and (2). (1) In a method of rolling a sheet material using a reversible rolling mill, a sheet crown before an i-th pass, a sheet crown after an i-th pass, and flatness are actually measured, and rolling data of an i-th pass is collected. The sheet crown after the i-th pass is calculated by the sheet crown model using the measured value of the sheet crown before the pass and the rolling data of the i-th pass, and the calculated value of the sheet crown after the i-th pass is the sheet after the i-th pass. The roll profile is calculated so as to match the measured value of the crown, and the flatness after the i-th pass is calculated from the measured values of the sheet crown before the i-th pass and after the i-th pass using a flatness calculation model, and The measured flatness after the pass,
An error of the flatness calculation model is calculated from the flatness calculation value obtained by the flatness calculation model, and the error of the flatness calculation model is obtained in at least one of the (i + 1) th and subsequent passes and the subsequent plate material pass. A pass schedule setting calculation is performed using the obtained roll profile, a work roll bending force setting calculation for correcting an error of the flatness calculation model is performed, and the calculated pass schedule and the work roll bending force are used. A method for rolling a sheet material of a reversible rolling mill, characterized in that:

(2) In the method of rolling a sheet material using a reversible rolling mill, the sheet crown before the (i-1) th pass, the sheet crown after the ith pass, and the flatness are measured.
1) The rolling data of the pass and the i-th pass are collected, and
-1) The sheet crown after the i-th pass is calculated by a sheet crown model using the actually measured value of the sheet crown before the pass, the rolling data of the (i-1) th pass, and the rolling data of the i-th pass, and
The roll profile and the sheet crown before the i-th pass are calculated so that the calculated value of the sheet crown after the i-th pass matches the actually measured value of the sheet crown after the i-th pass. The flatness after the i-th pass is calculated by the flatness calculation model from the actually measured crown value after the i-th pass, and the measured flatness after the i-th pass and the flatness calculation value obtained by the flatness calculation model are calculated. The error of the flatness calculation model is calculated from
+1) In at least one of the passes after the pass and the pass of the subsequent sheet material, the pass schedule setting calculation is performed using the roll profile obtained above, and the error of the flatness calculation model is corrected. A method for rolling a sheet material of a reversible rolling mill, wherein a work roll bending force setting calculation is performed, and rolling is performed using the calculated pass schedule and work roll bending force.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where a thick steel plate is rolled by a single-stand reversible rolling mill will be described as an example.

FIG. 1 is a schematic view of a rolling mill for thick steel plates.
FIG. 1A is a side view, and FIG. 1B is a plan view. The sheet material 1 is supplied to the rolling mill 2 via the table roller 7 from the left side in the figure in the form of a slab or in the form of an intermediate material that has been subjected to tentering rolling in the preceding rolling mill. A front center thickness gauge 5-1 such as a radiation transmission type, a front edge thickness gauge 5-2 on the front side (upstream side) of the rolling mill, and a rear center thickness gauge 6-1 on the rear side (downstream side). A rear surface thickness gauge 6-2, and a laser type flatness meter 8 are further disposed on the rear surface side.

The front center thickness gauge 5-1 is fixed at the center of the plate width. The front edge thickness gauge 5-2 is movable in the width direction, and measures the thickness of the width end (edge) of the plate 1. The difference in thickness between the front center thickness gauge 5-1 and the front edge thickness gauge 5-2 represents a plate crown. Similarly, on the rear side of the rolling mill, the sheet thickness and the sheet crown are measured by the rear center thickness gauge 6-1 and the rear edge thickness gauge 6-2. Depending on the equipment, the front thickness gauges 5-1 and 5-2 may not be installed. The thickness gauges 5-1 and 5-2 and the thickness gauges 6-1 and 6-2 are collectively referred to as a front board crown meter 5 and a rear board crown meter 6, respectively.

The flatness meter 8 has a plurality of laser type distance meters arranged in the width direction, and calculates the flatness of the steel sheet by the steepness represented by the following equation based on the measured distance data. .

A steepness λ = A / p × 100 (%) where A is the average wave height in the longitudinal direction of the rolled material, and p is the average wave pitch in the longitudinal direction of the rolled material.

The method of implementing the present invention will be described below with reference to the flowchart shown in FIG. Whether the sheet crown meter is installed on both the front and back of the rolling mill (CASE
1) or installed on only one side (this is CA
SE2).

That is, if both are installed, the i-th
The sheet crown can be measured before the pass and after the i-th pass, and the roll profile can be obtained only from the rolling data of the i-th pass. When a sheet crown meter is installed on only one side (usually on the rear side of the rolling mill), the sheet crown actual value required for roll profile calculation is calculated before the (i-1) th pass and the i-th sheet.
Can only be obtained after the pass. Therefore, the rolling data of the (i-1) th and i-th passes is used for the calculation of the roll profile.

CASE 1: A case where a sheet crown meter is installed on both the front surface and the rear surface. In FIG. 2, each processing step (represented as S1 and S2) in FIG. 2 will be described.

S1: The processing flow is changed depending on whether the sheet crown meter is installed on both the front side and the rear side of the rolling mill or only on the rear side. This CASE
In the case of 1, since it is installed in both, the process proceeds to S4. Next, the rolling direction is confirmed. That is, when the sheet material is rolled from the front side to the rear side, the front side is determined to be the entrance side, and the rear side is determined to be the exit side. Conversely, when rolling is performed from the rear side to the front side, it is determined that the rear side is the entrance side and the front side is the exit side. now,
The example of the present invention will be described on the assumption that the i-th pass is rolled from the front side to the rear side.

S 4: The crown before the i-th pass is actually measured by the front-plate crown meter 5. S5: Collect i-th pass rolling data. S6: After completion of the i-th pass, the sheet crown is actually measured by the rear face sheet crown meter 6, and the flatness is actually measured by the rear face flatness meter 8.

S7: S7 to S19 are roll profile calculation processing. First, an initial value of the roll profile is assumed in S7. The initial value is arbitrary, but an initial crown value or a value calculated immediately before may be used. The initial value is assumed to be an ordinary calculation method when a roll profile is obtained by iterative calculation when the sheet crown model is described in the form of a multiple simultaneous equation.

S8: In the case of CASE1, the process proceeds to S10 because there is a crown meter on both the front side and the rear side.

S10: The i-th pass calculation mode is set, and calculation is performed only for the i-th pass. The calculation mode refers to the calculation steps from S11 to S16 as the (i-1) th.
A switch on the software for selecting whether to calculate using the rolling data of the pass or the rolling data of the i-th pass, and is also used in the flow control step of S17. That is, the switch on the software is also a means for describing CASE1 and CASE2 described later in the same flowchart.

S12 to S16: Calculation of convergence of the rolling load distribution and the sheet crown by the roll split model. When S16 ends, a calculated value of the plate crown is obtained as a convergence result. The outline of this calculation method will be described below.

[0045] The inventors have calculated the crown calculation model as
A commonly used division model was used. The division model is a method of dividing the roll barrel portion (roll width) into minute regions and calculating the roll deformation for each division section by numerical calculation, and is obtained from the measured rolling data based on the rolling theory. There is a detailed description in the above-mentioned document. The outline of the calculation method is as follows.

S11: Assume a rolling load P (x) in a unit section at a position x in the width direction. In the division model, the roll width was set to 40 divisions (one side width is symmetrical to 20 divisions). In the following equations, the numbers of the divided sections in the width direction x are represented by j or k.

S12: The displacement of the work roll axis is V
Let _WX (x) be a function of P (x), q (x), Δz and α (j, k),

[0048]

(Equation 2)

And can be calculated by the method described in the literature.

Here, x: position in the width direction of the roll (0 at the center of the roll), P (x): rolling load of the divided section between the plate material and the work roll (the total width corresponds to the measured rolling load value) ), Q (x): Load in the divided section between the work roll and the backup roll, which is obtained from the equilibrium condition of the vertical force and the matching condition of the displacement of the contact portion between the work roll and the backup roll. Δz: Division width, α (j, k): Influence coefficient of roll axis center displacement, jth due to bending and shearing when a unit load is applied to the center of the kth division This is the roll axis center displacement at the center of the divided section. Calculated from the theory of a two-point elastic beam.

S13: The surface displacement of the work roll is V
_WS (x), P (x), E, ν, Δz and l _d
In the form of

[0052]

(Equation 3)

Can also be calculated by the method described in the above-mentioned document. Here, E: Young's modulus of the work roll, [nu: Poisson's ratio of the work rolls, l _d: Contact arc length of the material and the work rolls, it is.

S14: The thickness distribution h (x) in the width direction is given by the following equation.

[0055]

(Equation 4)

Here, h (0) is the thickness at the center in the width direction on the roll-out side, and R _C (x) is the difference between the diameter of the roll crown at the center in the barrel direction and the diameter of the edge when no load is applied. R _C0 is given by, for example, a quadratic function of equation (4).

R _C (x) = (2R _C0 / B _L ² ) · x ² (4) where R _C (x): roll crown at width position x R _C0 : roll crown B _L at no load : Work roll barrel length.

S15: The load distribution P (x) is expressed by the following equation (5) using the exit side thickness distribution h (x) obtained by the equation (3) and the entrance crown. Can be calculated by the method described in the above literature.

[0059]

(Equation 5)

Here, H ₀ : the center plate thickness before the i-th pass (calculated from the measured value of the thickness gauge or rolling data), and C _B : the crown of the i-th front plate (from the measured value of the sheet crown or the rolling data). K _fm : average deformation resistance, W _RB : work roll bending force, B: strip width (measured rolling data).

The above equations (1) to (5) are repeatedly calculated until the load distribution P (x) converges, that is, until the determination in S16.

The thickness distribution h (x) on the roll-out side in the width direction is obtained from the above equation (3), and the outlet-side sheet crown _Ch2 is given by the following equation (6).

Ch ₂ = h _c2 −h _e2 (6) where h _c2 is the thickness of the outgoing plate at the center position in the width direction he _e2 is the thickness of the outgoing plate at the edge portion (point inside the fixed distance from the edge, book In the example of the invention, the edge is calculated at 150 mm.

[0064]

(Equation 6)

Here, the first digit of the subscript “1” is before rolling,
"2" means after rolling.

S16: The convergence of the calculation of the load distribution P (x) is confirmed (if the difference between the previous and current calculated values is within the allowable error range, the calculation ends and the process proceeds to S17).

S17: Since the calculation mode was previously set in the i-th pass, the calculation ends and the flow proceeds to S18. That is, a CASE with a sheet crown meter on the front and back of the rolling mill
In the case of 1, the process proceeds to S18 with only the calculation for one pass.

S18: The calculated value of the above-mentioned crown of the sheet is compared with the actually measured value of the sheet crown by the rear-side sheet crown meter 6. If the two do not match within the allowable error, the process returns to S19, and the roll profile temporarily set in S7 is corrected to
8, S10 and S11 to S17 are repeated.

If the calculated value of the sheet crown and the actually measured value match (converge) within an allowable error, the roll profile calculation is terminated, and the flow proceeds to S20.

S20: As a result of the repeated calculation up to S18,
A roll profile is required.

S21: Next, from the actually measured sheet crown values before and after the i-th pass, a sheet crown ratio change Δγ is calculated according to equation (7).

S22: Using the sheet crown ratio change Δγ obtained in S21, the i-th calculation model shown in the following (8) to (10) is used.
The steepness λ after the pass is calculated.

[0073]

(Equation 7)

Here, the coefficient a is called a shape conversion coefficient, and is a function of the sheet width, the sheet thickness, etc., and various expressions have been proposed so far. Here, the following formula adopted by the present inventors from detailed studies is exemplified.

[0075]

(Equation 8)

[0076]

(Equation 9)

Here, B: plate width, Δh: reduction amount before and after i-th rolling = h _c1 −h _c2 .

S23: As described above, an error occurs in the prediction of the steepness due to variations in the plate temperature distribution in the plate, the distribution of the friction coefficient between the WR and the material, and the like. A steepness prediction error Δλ is obtained from the steepness λ obtained in S22 and the actually measured steepness λ ′ measured after the i-th pass.

Δλ = λ′-λ (11) S24: From the steepness prediction error Δλ obtained in S23, the WR bending force for correcting this is determined as follows.

In equation (8), λ is substituted for the left side, and (9)
, (10) is used to inversely calculate Δγ. Δ obtained here
If γ is Δγ ′, the WR bending force may be determined so as to cancel Δγ ′.

Since the WR vendor operates specifically on the (i + 1) th and subsequent passes, it is assumed here that the prediction error Δγ ′ is taken over as it is for the (i + 1) th and subsequent passes. Is determined as follows.

First, Δγ is calculated for the control target path on which the WR vendor operates by using the above (1) to (7).
WR bending in this calculation uses an initial set value. Next, Δγ ″ (= Δγ + Δγ ′) is calculated by adding the above-described prediction error Δγ ′ to the obtained Δγ, and this Δγ ″ is calculated.
WR bending force W _RB that matches
The WR bending force W _RB for correcting the prediction error Δγ ′ is determined by repeatedly calculating from the equation (7).

CASE 2: Case where a sheet crown meter is installed only on the rear surface (usually in many cases).

In this case, after the sheet crown before rolling is measured by the rear sheet crown meter 6, the sheet crown is measured again by the rear sheet crown meter 6 after rolling through two passes.

The calculation procedure will be described with reference to the flowchart of FIG. S1: Since the sheet crown meter is only on the rear side, the process proceeds to S2. S2: The crown of the rear plate is measured by the rear plate crown meter 6, and the measured value is the (i-1) th pass front plate crown measured value.

S3: Rolling is performed, and (i-1) th pass rolling data is collected. S5: The roll is reversed, and the rolling is executed to collect the i-th rolling data. S6: The sheet crown is again measured by the rear-side sheet crown meter 6, and the measured value is used as the measured value of the i-th rear sheet crown. Further, the flatness is measured by a rear flatness meter 8.

S7: As in CASE1, assume an initial roll profile value. S8: In CASE2, there is no sheet crown meter 5 on the front surface, so the process proceeds to S9. S9: First, the (i-1) th pass is calculated, and then
The process returns from S17 to S11 via S10, and calculates the i-th pass. That is, calculation for two passes is performed. In the calculation of the (i-1) th pass, the (i-1) th rolling is performed using the measured value of the sheet crown before the (i-1) th pass and the (i-1) th pass rolling data.
The calculated value of the sheet crown after the pass, that is, the calculated value of the sheet crown before the i-th pass, is determined. This calculated value is regarded as the “actually measured value” of the sheet crown before the i-th pass, and the calculation of the next i-th pass is performed. Used for

The calculation steps after S11 are based on the above-mentioned CASE.
This is the same as “1. When the crown is installed on both the front surface and the rear surface”, the calculated value of the roll profile is determined at the stage of S20 after the convergence calculation is completed, and the flatness is determined at the stage of S24. A WR bending force for correcting the prediction error is required. However, in the calculation of the sheet crown ratio change Δγ in S21, since there is no sheet crown actual measurement value before and after the i-th pass rolling as in CASE1, S1
The calculated values of the crown of the sheet after the (i-1) th pass (that is, the calculated values of the crown of the sheet before the ith pass) and the ith of the
The plate crown ratio change of the i-th pass is obtained from the measured plate crown value obtained by actual measurement after the pass rolling.

When the (i-1) th pass is used as a dummy pass when the strip crown meter is installed only on the rear surface, the strip crown can be measured before and after the i-th pass. A similar calculation process may be performed.

[0090]

EXAMPLE A steel plate rolling mill having the specifications shown in Table 1 was used in the confirmation test of the present invention. Since the sheet crown meter is installed only on the rear surface of the rolling mill, the method of CASE 2 of the method of the present invention was applied.

[0091]

[Table 1]

The roll profile calculation model of the present invention is applied, and the path schedule calculation and WR using this value are performed.
Rolling using bending was performed.

The roll profile calculation pass is the last pass 2
Before the pass (this is referred to as (final-2) pass; the rolling direction is the forward direction). Before the (final-3) pass, the sheet material is actually measured by a rear face crown meter, and rolling data is collected in each of the (final-3) pass (reverse direction) and the (final-2) pass (forward direction), and the roll profile is obtained. Was calculated. Furthermore, after the rolling of the (final-2) pass, the flatness of the plate was measured by a rear flatness meter. A flatness prediction error was calculated from the difference between the actually measured flatness and the calculated flatness calculated from the change in the sheet crown ratio before and after the (final-2) pass obtained during the roll profile calculation. Using the work roll profile and the flatness prediction error obtained here, the pass schedule calculation and the WR bending force calculation of (final-1) and final pass were performed, and rolling was performed by setting these values.

FIG. 3 is a graph showing the transition of the plate shape (steepness) at the roll chance to which the present invention is applied.

As a comparative example, the W
R bending force calculation was performed and rolling was performed.

The roll profile was estimated from a roll wear + heat crown model formula conventionally incorporated in the pass schedule calculation of the rolling mill.

The calculation of flatness is described in JP-A-3-3241.
As disclosed in Japanese Unexamined Patent Publication No. 2 (1994), rolling data (rolling load, WR bending force, etc.), flatness, and sheet crown are actually measured during a rolling pass (here, the last -2 pass), and a roll is determined from the measured data. A profile prediction error, a sheet crown prediction error, and a rolling load prediction error were obtained, a WR bending force for correcting these errors was determined, and rolling in the final pass was performed. The prediction error was obtained using Δγ = (π / 2 · λ) ² as the relational expression between the flatness λ and the plate crown ratio change Δγ.

FIG. 4 is a graph showing the transition of the plate shape (steepness) at the roll chance of the comparative example.

A comparison between FIG. 3 and FIG. 4 shows that the rolling using the present invention had a good plate shape over the entire roll chance, whereas the rolling according to the comparative example had a bad plate shape and varied greatly. .

[0100]

According to the present invention, it is possible to accurately obtain a roll profile that changes every moment, and to accurately correct a prediction error caused by a plate temperature distribution in a plate which is difficult to predict. As a result, tremendous effects such as improvement in the quality of the plate crown, plate shape, and yield of the plate material can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a plate rolling mill, wherein FIG. 1 (a) is a side view and FIG. 1 (b) is a plan view.

FIG. 2 is a flowchart showing a calculation procedure of the present invention.

FIG. 3 is a graph showing a change in steepness of a sheet shape when the present invention is rolled.

FIG. 4 is a graph showing a change in steepness of a plate shape when rolling is performed by applying a conventional method.

[Explanation of symbols]

1: Plate material 2: Rolling mill 3: Work roll 4: Backup roll 5: Front plate crown meter (general term for front center / edge thickness gauge) 5-1: Front center thickness gauge 5-2: Front edge thickness gauge 6: Rear panel crown meter (general term for front center and edge thickness gauge) 6-1: Rear center thickness gauge 6-2: Rear edge thickness gauge 7: Table roller 8: Flatness meter

Claims (2)

[Claims] In a method of rolling a sheet material using a reversible rolling mill, a sheet crown before an i-th pass, a sheet crown after an i-th pass, and flatness are measured, and rolling data of an i-th pass is collected. The sheet crown after the i-th pass is calculated by a sheet crown model using the measured value of the sheet crown before the i-th pass and the rolling data of the i-th pass, and the calculated value of the sheet crown after the i-th pass is obtained after the i-th pass. The roll profile was calculated to match the measured value of the sheet crown of
The flatness after the i-th pass is calculated by the flatness calculation model from the actually measured value of the plate crown after the pass, and the measured flatness after the i-th pass and the flatness calculation obtained by the flatness calculation model And the error of the flatness calculation model is calculated from the values, and at least one of the paths after the (i + 1) th pass and the path of the subsequent sheet material is calculated.
In one pass, a pass schedule setting calculation is performed using the roll profile obtained above, and a work roll bending force setting calculation for correcting an error of the flatness calculation model is performed, and the calculated pass schedule is calculated. And a method of rolling a sheet material of a reversible rolling mill, wherein the rolling is performed using a work roll bending force. 2. A method for rolling a sheet material using a reversible rolling mill, wherein the sheet crown before the (i-1) th pass and the ith sheet crown are provided.
The crown and flatness after the pass were measured, and the (i-
1) The rolling data of the pass and the i-th pass are collected, and
-1) The sheet crown after the i-th pass is calculated by a sheet crown model using the actually measured value of the sheet crown before the pass, the rolling data of the (i-1) th pass, and the rolling data of the i-th pass, and
The roll profile and the sheet crown before the i-th pass are calculated so that the calculated value of the sheet crown after the i-th pass matches the actually measured value of the sheet crown after the i-th pass. The flatness after the i-th pass is calculated by the flatness calculation model from the actually measured crown value after the i-th pass, and the measured flatness after the i-th pass and the flatness calculation value obtained by the flatness calculation model are calculated. The error of the flatness calculation model is calculated from
+1) In at least one of the passes after the pass and the pass of the subsequent sheet material, the pass schedule setting calculation is performed using the roll profile obtained above, and the error of the flatness calculation model is corrected. A method for rolling a sheet material of a reversible rolling mill, wherein a work roll bending force setting calculation is performed, and rolling is performed using the calculated pass schedule and work roll bending force.