JP2002282919A - Learning calculation method for roll profile in plate rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a learning calculation method for roll profile which improves calculation accuracy to set up a plate crown and shape for thin gage rolling in a continuous hot rolling mill. SOLUTION: In a calculation method for an estimation error of the roll profile based on a difference between either plate crown or shape, or both of them calculated from rolling conditions or the actual rolling data of a preceding rolled piece, and either plate crown or shape, or both of them of the rolled piece measured after rolling, the influence of widthwise temperature distribution estimated by a rolling temperature model on the plate crown of the rolled piece is calculated, and the influenced amount and the roll profile estimation error are separated. The calculation of the roll profile estimation error enables achieving the target plate crown and shape after rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rolling control for achieving a target crown crown plate shape by computer control performed using a crown crown plate shape estimation model, and more particularly, to a measured crown crown plate shape and the estimation. The present invention relates to a method of correcting a roll profile used for learning calculation of a difference from a model as a roll profile and for use in setting calculation of a succeeding material.

[0002]

2. Description of the Related Art In order to achieve a target strip crown shape after rolling by computer control of a strip crown and a strip shape of a rolled material, first, when a rolling condition is given, a strip crown and a strip formed by the rolling are first obtained. A model that expresses the plate shape with practical accuracy, that is, a plate crown and a plate shape prediction model is required. This model is roughly classified as follows from physical phenomena in rolling. (A) Analysis model for elastic deformation of roll (b) Model for analyzing deformation characteristics of rolled material (c) Model for estimating roll profile

[0003] Of the above models, (a) and (b)
For example, JP-A-59-215205 discloses
It is disclosed in the report. In this method, representative of roll deformation
Parameter between the rolled material and the work roll
Plate crown realized when the load distribution in the width direction is uniform
The mechanical crown at the defined point
_MIs defined as Method calculated by rolling conditions
Cyanical plate crown C _MDepends on the mill type
However, for example, in a four-high rolling mill, sheet crown and sheet shape control are performed.
If you have only a work roll bender at the end,
It is known to be calculated as C_M= A_P・ P + A_F・ F + A_RC_R (1) Here, P is the rolling load, and F is the work roll bending.
Power, C_RIs the roll profile converted to the sheet crown definition point.
And A_P, A_F, A_RIs mill form, mill dimension
John as a function of rolling conditions such as strip width
Model coefficients.

[0004] The mechanical sheet crown _CM is an amount of deformation determined only by the deformation characteristics of the rolling mill, but the load distribution in the width direction in actual rolling is caused by the incoming side sheet crown, the metal flow in the width direction of the rolled material, and the like. since variously changes by the material deformation properties, the delivery side crown C _h, does not match the mechanical strip crown, it is generally expressed by the following equation. C _h = (1−η) C _M + η (1−r) C _H (2) where η is the crown ratio inheritance coefficient, r is the rolling reduction, C _H
Is an entrance side plate crown. Of the analysis models described above,
Regarding (a) and (b), a model for calculating the plate crown with practical accuracy is disclosed in the above-mentioned patent publication.

On the other hand, as for the roll profile estimation model, for example, although the thermal expansion calculation method itself has been almost established, the boundary conditions used in the calculation, that is, the region where the cooling water is applied to the work roll and the heat transfer coefficient thereof are described. In some cases, it is difficult to say that the roll profile has always been accurately estimated, in some cases, such as the condition relating to the heat input of the roll in the roll bite. A conventional technique for correcting the roll profile estimation error is also disclosed in Japanese Patent Application Laid-Open No. Sho 59-215205.

Here, in the above prior art, the calculation of the sheet crown and the sheet shape on the exit side of the final stand is performed using the above equations (1) and (2) based on the actual rolling performance of the rolled material.
The difference between the calculated plate crown and the plate crown and plate shape actually measured on the exit side of the final stand is calculated. At this time,
Since the rolling load and the work roll bender force, which are the rolling parameters of the formula (1), use the rolling results, it is assumed that most of the sheet crown difference is caused by a roll profile estimation error, and correction means is disclosed. ing.
More specifically, the difference between the plate crowns is expressed by the equation (2).
The mechanical crown error ΔC _M at each stand is calculated using the above. As described above, as all the roll profile estimation error of the mechanical strip crown error [Delta] C _M, using the influence coefficients A _R of the roll profile of the formula (1), it is calculated by the following equation. ΔC = ΔC _M / A _R (3) Here, ΔC is the correction amount of the roll profile at the sheet crown defining point (the position corresponding to the actual sheet crown) of the rolled material.

However, as described above, the mechanical plate crown of the formula (1) is a plate crown at the position of the plate crown defining point which is realized when the load distribution in the width direction between the rolled material and the work roll is uniform. It is a crown, meaning that this is achieved when the rolled material has a uniform temperature distribution in the width direction. In actual operation, the rolled material due to the presence of the plate width direction temperature distribution, the mechanical strip crown C _M calculated from equation (1), there is an error with respect to actual operation. That is, in the above-described conventional technology, a significant error is also caused in the roll profile correction amount calculated from the equation (3), which causes a sheet shape to be disturbed particularly in thin rolling, and causes a threading trouble. Was.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. In particular, the present invention maintains good calculation accuracy for setting a sheet crown and a sheet shape in thin rolling, and sets a target sheet crown and a target sheet crown after rolling. A roll profile learning calculation method for obtaining a plate shape is provided.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the gist of the present invention is to provide a hot finish rolling mill having a plurality of rolling stands and a target plate using a plate crown plate shape prediction model. In the setting calculation for obtaining the crown and the plate shape, one or both of the plate crown and the plate shape calculated from the rolling conditions or the rolling results of the preceding material, and the plate crown and the plate actually measured after the rolling of the rolled material In the method of calculating the roll profile estimation error from the difference between one or both of the shapes, in the hot finish rolling row in the rolling stand in each rolling stand to calculate the temperature distribution of the rolled material in the width direction, the rolling stand in each rolling stand The amount of influence of the temperature distribution in the width direction of the rolled sheet on the sheet crown is calculated, and the roll profile is added to the sheet crown sheet shape prediction model in consideration of the amount of influence. It is a roll profile learning calculation method in the plate rolling and calculates an estimation error.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors investigated the effect of the temperature distribution in the width direction of a rolled material strip on the shape of a thin rolled sheet, and determined that the temperature distribution between the stands at the entry side of the final stand in the row of rolled material hot rolling mills. FIG. 2 shows the results obtained by changing the cooling conditions in the coil and actually measuring the temperature distribution in the sheet width direction, the sheet crown and the sheet shape on the exit side of the final stand. It was found that when the finished plate thickness was small, the error itself of the measured plate crown value itself due to the difference in cooling conditions was small, but the influence on the plate shape was large. That is, it has been found that even if the rolling conditions including the roll profile of the final stand are the same, if the rolled material has a temperature distribution in the plate width direction, the plate shape changes significantly. From this, it is considered that all the factors of sheet crown plate shape fluctuation caused by the above-mentioned sheet width direction temperature distribution as the roll profile estimation error as in the prior art are factors of the sheet crown shape estimation error of the succeeding rolled material. I understand. Moreover, as can be seen from the mechanical plate crown calculation formula shown in the equation (1), the plate crown, that is, the influence term relating to the displacement, is a mechanical force (rolling load or bender force) or a direct transfer term (roll profile). ). In consideration of the above-mentioned temperature distribution in the sheet width direction, generally, as an influence item on the sheet crown, a distribution of the rolling load in the sheet width direction or a distribution of the deformation resistance in the sheet width direction can be considered. Further, for example, the relationship between the deformation resistance K _f and rolled material width direction distribution is known to be expressed by a function, such as simplified manner the following equation.

(Equation 1)

Therefore, the inventors have found that the distribution in the width direction of the deformation resistance due to the temperature distribution in the width direction of the rolled material, for example, is expressed by the following equation (1).
The influence on the mechanical plate crown type shown in the above was investigated. At this time, for example, by using a three-dimensional rigid-plastic finite element method, based on the rolling analysis results in which a temperature distribution, that is, a deformation resistance distribution is given in the sheet width direction, the inlet and outlet calculation sheet crowns and the above equations (1), (2) ), (4) using a deformation resistance distribution in the plate width direction is extracted effect on the mechanical strip crown C _M. As a result, deformation resistance difference in the strip plate central portion and the strip crown defining point position △ K _f and it was found that a strong correlation to the effect on the mechanical strip crown C _M, and in the formula (1) Shown mechanical plate crown C
It turns out that _M can be expressed as follows. _{C M = A P · P +} A F · F + A R C R + A Kf · △ K f (5) Here, A _kf is the influence coefficient of deformation resistance distribution has on the mechanical strip crown, it advance above △ K _f is the results of analysis of influence of the mechanical strip crown C _M, it suffices to model the like rolling factor.

At this time, T (z), that is, the temperature distribution in the width direction of the rolled material expressed by the equation (4) is obtained by, for example, calculating the boundary condition in the hot rolling process in a heat conduction equation corresponding to the rolled material. In addition, it can be calculated from the rolled material temperature model based on the difference calculation, the finite element method, or the simple calculation.

In the present invention, the mechanical plate crown formula of the formula (1) used in the prior art is changed to the formula (5),
The roll profile correction amount will be calculated. In the case of the present invention, it is possible to correct and learn the roll profile with high accuracy in consideration of the influence of the inevitable temperature distribution in the sheet width direction on the sheet crown shape. It can be performed with higher accuracy than the conventional technology. The specific method of the present invention will be described in detail in the following examples.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A procedure for calculating a work roll correction amount using a difference between an actually measured strip crown after rolling and an estimated strip crown calculated using a strip crown shape prediction model according to the present invention will be specifically described. At this time, the present invention will be specifically described in a case where the present invention is applied to a row of hot rolling mills. Now, it is assumed that the actually measured value of the finish plate crown at the exit of the final stand is C _N ^d and the calculated value is C _N. At this time, the plate crown calculation value is
At the end of rolling of the preceding rolled material, the results of rolling are collected, and the final stand exit side sheet crown is calculated based on the results of rolling. In this case, in the present invention, the temperature distribution in the sheet width direction of each finishing stand is calculated by using a rolled material temperature prediction model at the time of setting calculation, and is combined with the above-mentioned rolling results, using the equation (2) and the equation (5) according to the present invention. ) Is used to calculate the performance calculation plate crown at each stand from the upstream stand to the downstream based on the rolling performance, and calculate the final stand exit side plate crown C _N
Ask for. Here, in the present invention, the calculated value of the temperature distribution in the plate width direction of each stand is calculated at the time of setting calculation, but, for example, when there is a device for actually measuring the temperature distribution in the plate width direction on the exit side of the final stand, the measured value is The difference in the sheet width direction temperature distribution calculated at the time of the above setting calculation is detected, and the heat flow rate conditions relating to the rolled material surface of the rolled material temperature model are corrected so as to eliminate the difference, and at each of the recalculated finishing stands, May be used. According to the present invention, when calculating the actual strip crown, the equation (5) considering the influence of the temperature distribution in the strip width direction is applied, and the calculation C _N of the final stand exit side strip crown including the influence is applied. I will ask.

At this time, a sheet crown calculation error to be learned as a roll profile is given by the following equation. ΔC _N = C _N ^d −C _N (6) At this time, in the case of a tandem rolling mill, there are a plurality of roll profiles to be learned. The amount of mechanical plate crown correction of each stand of the finishing mill train is calculated using the method described above, and the roll profile learning calculation method according to the present invention using the corrected amount will be described.

In this case, if the condition that the plate shape on the exit side of the final stand is maintained as it is (change of the crown ratio is constant), the final stand entrance side plate crown correction amount can be obtained by the following equation. ΔC _N-1 / h _N-1 = ΔC _N / h _N (7) 1 stand to N-2 stand delivery side of the strip crown correction amount _{△ C 1, ... △ C N} -2 are given the effect on the interstand shape by the following equation from the condition of minimizing. ξ ₁ (△ C ₁ / h ₁ ) = ξ ₂ (△ C ₂ / h _2- △ C ₁ / h ₁ ) =... = ξ _N-1 (△ C _N-1 / h _N-1- △) C _N−2 / h _N−2 ) (8) Here, ξ is a shape change coefficient calculated from rolling conditions of each stand of the finishing mill.

If ΔCj / hj in equation (8) is Aj and the value of each term is X, equation (8) can be expressed by the following equation. _{ξ 1 A 1 = ξ 2 (} A 2 -A 1) = ......... = ξ N-1 (A N-1 -A N-2) = X (9) Furthermore, the identity shown in the following equation with respect to Aj It turns out that it holds. A ₁ + (A ₂ −A ₁ ) +... + (A _N−1 −A _N−2 ) = A _N−1 = △ C _N−1 / h _N−1 (10) By substituting equation (9) into the left side and rearranging by X in equation (9), the following equation is obtained. X = {C _N-1 / ｛h _N-1 (1 / ξ ₁ + 1 / ξ ₂ +... + 1 / ξ _N-1 )} (11)

By substituting equation (11) into equation (9), Aj is calculated, and from the definition of Aj, the sheet crown correction amount △ Cj of each stand of the finishing mill can be obtained. Here, the subscript j is 1 to N. From ΔCj, the mechanical plate crown correction amount of each stand of the finishing mill is calculated from the following equation by back calculation from equation (2). _{ΔC M j = (△ Cj-} ηj (1-rj) △ Cj-1) / (1-ηj) (12) At this time, as described above, the mechanical strip crown correction of each stand is calculated by the formula (12) the amount [Delta] C _M j is calculated based on the calculated strip crown C _N calculated using rolling results. From this, most of the correction amount is
The amount of correction of the roll profile, and the amount of correction of the roll profile of each stand △ Cj, is the influence coefficient A _R j of the roll profile of equation (5) on the mechanical plate crown.
Is calculated using the following equation. ΔCj = ΔC _M j / A _R j (13)

Here, it should be noted that ΔCj corresponds to the position of the sheet crown defining point of the preceding rolled material (the position corresponding to the actual sheet crown). At this time, if there is no change in the strip width of the rolled material, the roll profile correction amount itself obtained from Expression (13) can be used as a learning term. However, in actual operation, since the strip width changes frequently, It is necessary to extend the roll profile correction amount of the equation (13) obtained at the position of the sheet crown definition point in the roll axis direction and to learn. In general, this expansion method
A method of expressing the correction amount of the roll profile as an nth-order curve distribution is used, and this method is also adopted here, and the roll axis distribution △ C _WR j of the correction amount of the roll profile is determined by the following equation. ΔC _WR j = f _WR j · x ⁿ (14) where x is a coordinate with the origin at the center of the roll body length,
f _WR j can be given by the following equation, where b is the plate width of the preceding material and β is a point from the plate edge at the position of the plate crown defining point. f _WR j = △ C _WR ^b j / (b / 2−β) ⁿ (15)

That is, if f _WR j obtained by the equation (15) is stored as a learning term, universal learning can be performed even when the rolled sheet width changes according to the equation (14). Generally, the learning term f _WR j calculated from the equation (15) may include a disturbance of the latest preceding material, and the learning gain G _WR j may be reduced for the purpose of reducing this influence.
Multiplied by (0 <G <1), the method has been taken to continue to update the learning term f _WR j ^o so far as the following equation. f _WR j ^N = G _WR · f _WR j + f _WR ^jo (16)

The learning term f _WR j ^N obtained from equation (14)
Therefore, the roll profile of the succeeding rolled material at the sheet crown definition point position is calculated by using the equation (14), and the calculation of the setting of the sheet crown and the sheet shape of the subsequent rolled material may be performed using this value. Here, it is practical to tune n in Expression (14) and G in Expression (16) based on the analysis result of the rolling operation status and the like. Also here
Although the roll profile correction amount of the equation (13) obtained at the position of the sheet crown definition point has been described by adopting the nth order curve as a method of extending in the roll axis direction, it is not always necessary to stick to this function system. A trigonometric function or an exponential function may be employed. The equation (5) is also used in the calculation of the crown shape setting performed to obtain the target crown shape.
It is needless to say that if the control amount of the plate crown shape control end of each stand is determined by using a mechanical plate crown that can be calculated from the following formula, the plate crown shape estimation accuracy is improved.

In the roll profile learning calculation method of the prior art, the final stand exit side plate crown calculation value C _N is calculated by using the equation (1). That is, in the prior art,
As described in the section of [Prior Art], the calculated value C _N includes both the roll profile estimation value and the error that the temperature distribution in the width direction of the rolled material sheet exerts on the sheet crown. That is, in the case of the prior art, it means that the roll profile learning calculation is performed using all the estimation errors as the roll profile estimation errors. According to the present invention, when calculating the actual sheet crown, a model formula, Equation (5), which takes into account the influence of the temperature distribution in the sheet width direction on the sheet crown in advance, is applied. since calculates the plate crown calculated C _N, with respect to the roll profile learning calculation, it can be seen that calculated roll profile estimation error itself.

Further, with respect to the learning calculation methods for a plate shape, for example, the difference between the actual measurement plate shape as disclosed in JP 59-215205 and calculation plate shape, calculations for converting the mechanical strip crown correction amount [Delta] C _M Procedures are listed. At this time, the shape of the calculation plate on the exit side of the final stand also
It can be calculated from the calculation plate crown based on equations (2) and (5). The calculation procedure after obtaining the mechanical plate crown correction amount ΔC _M may be performed in exactly the same manner as the method shown in the above equation (13).

According to the present invention, the roll profile can be modified in consideration of the influence of the temperature distribution in the width direction of the sheet on the sheet crown shape as described above. Therefore, as shown in FIG. It can be seen that the setting accuracy is improved, and in particular, the plate shape estimation accuracy in thin rolling can be performed more accurately than in the related art. FIG.
Further, in a rolling schedule in which the sheet width is changed, in the related art, the setting accuracy of the sheet crown and the sheet shape is deteriorated, whereas in the present invention, it is greatly improved. In the prior art, the entire effect of the above-described temperature distribution in the sheet width direction on the mechanical sheet crown is taken as the roll profile correction amount. Therefore, the correction amount necessarily includes an error as described above. In the case of the same rolling schedule, the apparent correction is made in a form including the above-mentioned influence, but, for example, in the case of the strip width changing rolling schedule, as described above, the effect of the roll profile correction error up to the preceding rolled material is remarkable. It has also been found from comparison results with the present invention that, particularly, immediately after the width of the plate is changed, the plate crown shape setting accuracy deteriorates. In the case of the present invention, since the influence of the temperature distribution in the sheet width direction on the mechanical sheet crown is appropriately evaluated and extracted, and the roll profile correction amount is calculated, the accuracy is greatly improved as compared with the related art. You can see that it is.

[0025]

As described above, when the present invention is applied, compared with the prior art, in particular, the calculation accuracy of the crown crown plate shape setting in thin rolling can be improved, and the target plate on the final stand exit side can be obtained. A crown plate shape can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a comparison result between the present invention and a conventional technique.

FIG. 2 is a diagram for explaining the process of reaching the present invention.

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Claims (1)

[Claims] 1. A setting calculation for obtaining a target sheet crown and sheet shape using a sheet crown sheet shape predicting model in a hot finishing rolling mill row having a plurality of rolling stands, the rolling conditions or rolling results of the preceding material. In a method of calculating a roll profile estimation error from a difference between one or both of a sheet crown and a sheet shape calculated from and a difference between the sheet crown and one or both of a sheet crown and a sheet shape actually measured after rolling of the rolled material. Calculating the temperature distribution in the strip width direction of the rolled material at each rolling stand of the hot finish rolling row, calculating the amount of influence of the rolled material sheet width direction temperature distribution on the strip crown at each rolling stand, A roll profile study in sheet rolling, wherein an estimation error of a roll profile is calculated in consideration of the influence amount to a crown plate shape prediction model. Learning calculation method.