JP2758490B2 - Shape control method in sheet rolling - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape control method in sheet rolling, and more particularly to a shape control method when a sheet temperature is distributed in a sheet width direction.

INDUSTRIAL APPLICABILITY The present invention is used for cold or warm rolling of metal strips of ordinary steel, stainless steel, electromagnetic steel, titanium, titanium alloy and the like.

[Related Art] A rolled plate or a metal strip is required to have a good plate shape without shape defects such as ear waves and middle elongation. Conventionally, shape control has been widely performed to obtain a good plate shape. In order to control the plate shape, a model formula indicating the relationship between the shape distribution in the plate width direction and the shape operation amount is obtained in advance. Then, the shape distribution in the sheet width direction is detected on the delivery side of the rolling mill, and a shape manipulation amount is obtained from the detected shape distribution and the model formula.
The shape operation end is controlled based on the obtained shape operation amount. As the shape operation end, a work roll bender, an intermediate roll bender, an intermediate roll shift device, a work roll shift device, a split backup roll pushing device, or the like is used.

By the way, since the heat dissipation of the rolled plate is not uniform in the plate width direction, the temperature distribution in the plate width direction becomes uneven.
If the temperature distribution in the sheet width direction is not uniform, the rolled sheet undergoes thermal deformation when cooled from the rolling temperature to room temperature. Therefore, the plate shape during rolling is different from the plate shape after cooling, and the target plate shape cannot be obtained even if shape control is performed. In particular, in the case of warm rolling in which the temperature of the rolled material is 50 to 500 ° C. on the entry side of the rolling mill, the defect of the plate shape becomes remarkable.

In order to solve such a problem, the present inventors have developed a shape control method in consideration of the non-uniformity of the temperature distribution (Japanese Patent Application No. 1-76719, entitled "Shape Control in Hot or Cold Rolling of Sheet"). Method "). In this shape control method, after the plate is cooled on the exit side of the rolling mill, the shape distribution in the plate width direction and the plate temperature distribution are detected. Then, based on the detected value, the amount of the cooling medium sprayed in the sheet width direction is adjusted, and the shape operation end of the rolling mill is controlled so as to have the target sheet shape.

[Problems to be Solved by the Invention] However, in the above-described conventional shape control method, the temperature distribution and shape distribution on the roll bite exit side and the detected temperature distribution and shape are adjusted by adjusting the amount of cooling medium sprayed in the plate width direction. The distribution pattern differs greatly. Therefore, it is difficult to control the shape with high precision, and a good plate shape cannot be obtained.

Accordingly, an object of the present invention is to provide a shape control method capable of controlling the shape with high accuracy in sheet rolling.

[Means for Solving the Problems] According to the shape control method of the present invention, a model formula indicating the relationship between the shape distribution in the plate width direction and the shape operation amount is obtained in advance. The temperature distribution and the shape distribution in the sheet width direction are detected on the delivery side of the rolling mill, and these are approximated by four or more equations relating to a variable x indicating the position in the sheet width direction. Estimate the shape distribution in the direction. Then, a shape operation amount is obtained from the estimated shape distribution and the model formula, and the shape operation end is controlled.

In order to obtain the temperature distribution and the shape distribution in the plate width direction, the plate temperature and the plate shape are detected at a plurality of measurement positions along the plate width direction. The plate shape is determined, for example, as a steepness. The number of measurement positions is about 5 to 30. Then, from the point of calculation operation, the temperature distribution and the shape distribution are represented by a polynomial using the measurement position as a variable. Variable coefficients are determined by multiple regression. The model formula indicating the relationship between the shape distribution in the plate width direction and the shape operation amount is obtained in advance by experiments. The model formula is composed of a collection of linear formulas representing the plate shape for each measurement position in the plate width direction and the shape operation amount as a variable. Then, in order to obtain a required shape operation amount, the linear equations are solved simultaneously. The coefficients of the variables in the model formula are obtained by multiple regression through experiments. Examples of the shape operation amount include a bending force applied to the work roll and the intermediate roll, a roll shift amount of the work roll and the intermediate roll, and a pushing amount of the divided backup roll. Which of these shape manipulated variables is controlled depends on the type of rolling mill, rolling conditions, and the like. The obtained model formula half is stored in the control arithmetic unit, and is used when calculating a required shape operation amount based on the detected temperature distribution and shape distribution in the plate width direction.

For detecting the temperature of the rolled sheet, a thermoelectric thermometer, a resistance thermometer, a heat radiation thermometer, or the like is used. For detection of plate shape,
A known shape detector such as a magnetostrictive type, an optical type, a bending type, and a split roll type is used.

The shape distribution in the sheet width direction at room temperature can be expressed as a polynomial by considering the linear expansion coefficient of the rolled sheet based on the detected temperature distribution and shape distribution in the sheet width direction. In the above polynomial, the measurement position is a variable, and the coefficient of the variable is obtained by multiple regression.

[Operation] In the shape control method of the present invention, the shape distribution in the sheet width direction at room temperature is estimated based on the temperature distribution and the shape distribution in the sheet width direction of the rolled sheet in a high temperature state, and the estimated shape distribution is set as a target. The shape operation amount is obtained from the deviation from the shape distribution and the model formula, and the shape operation end is controlled. That is, shape control is performed so that shape defects such as ear waves and middle elongation generated in a high temperature state are absorbed by thermal deformation during cooling. Therefore, a good plate shape free from shape defects can be obtained at room temperature.

[Embodiment] Fig. 1 shows an example of a plate rolling facility for implementing the shape control method of the present invention.

The rolling mill 11 is a 12-high cluster rolling mill and includes a work roll 12, an intermediate roll 13, a central backup roll 16, and a side backup 17. Intermediate roll 13
Is provided with two tapered portions 14, 15 as shown in FIG. The side backup roll 17 is composed of five divided rolls 18 as shown in FIG. The eccentricity, that is, the pushing amount of each of the divided rolls 18 can be adjusted by rotation, whereby the crown of the work roll 12 can be formed into a required shape.

As a shape operating end, an intermediate roll bender 21 and an intermediate roll shift device 22 for the intermediate roll 13 and a split backup roll pushing device for the side backup roll 17
23 are provided respectively.

Adjacent to the exit side of the cluster rolling mill 11, a temperature detection device
25 are located. As shown in FIG. 4, the temperature detecting device 25 has a plurality of chromel-almer thermocouples 27 attached to the outer peripheral surface of a hollow roll 26. The surface of the hollow roll 26 is coated with alumina so that the thermocouple 27 is exposed. Therefore, the thermocouple 27 is in contact with the rolled plate S, and the space between the hollow roll 26 and the thermocouple 27 and between the thermocouples 27 are insulated. A conductive hole (not shown) communicating with the inside of the roll is provided on the surface of the hollow roll 26, and the thermocouple 27 is drawn into the roll from the conductive hole. The thermocouple 27 is connected from the hollow roll 26 via a slip ring 28 to a control arithmetic unit 31 via a signal processing circuit 29 having a standard device (not shown). Control arithmetic unit 31
, The target shape is input from the shape setting device 32.

A shape detection device 35 is arranged adjacent to the output side of the temperature detection device 25. The shape detection device 35 is of a magnetostrictive type, and is connected to the control operation device 31.

In the rolling equipment configured as described above, the temperature detecting device 25 and the shape detecting device 35 continuously detect the temperature and the plate shape of the rolled sheet S at an appropriate sampling interval (for example, 0.5 sec). The detected temperature value t and the detected plate shape value c are output to the control arithmetic unit 31. The control arithmetic unit 31 calculates the required intermediate roll bending force, the intermediate roll shift amount, and the split backup roll pushing amount of the side backup roll based on the detected values of the plate temperature and the plate shape by the following model formula. The calculation results are input to the controller 37, respectively, and the intermediate roll bender 21,
The intermediate roll shift device 22 and the split backup roll pushing device 23 are controlled.

Here, an example of a method of obtaining the shape manipulation amount from the detected temperature distribution and shape distribution will be described. Hereinafter, the plate shape is indicated by steepness.

The steepness λ (x) is expressed by the following equation (1) using the measurement position x in the plate width direction as a variable.

λ (x) = a ₁ x ⁴ + a ₂ x ³ + a ₃ x ² + a ₄ x + a ₅ (1) where −1 ≦ x ≦ 1, x = −1: plate end position x of the drive side plate = 1: Plate end position of plate on the work side The coefficients a _{1 to} a _{5 in} the equation (1) are obtained by detecting the steepness in the plate width direction by a shape detection device and performing multiple regression. It is desirable that the expression representing the steepness λ (x) is of the fourth order or higher with respect to x in terms of accuracy.

Based on the above equation, a symmetric component equation λ _s (x) = a ₁ x ⁴ + a ₃ x ² + a ₅ asymmetric component equation λ _a (x) = a ₂ x ³ + a ₄ x …… (2) I do.

 Next, shape evaluation parameters are obtained.

Next, using these four parameters, a plate shape when there is a temperature difference in the plate width direction is obtained.

The plate temperature T (x) is expressed by the following equation (4) using the measurement position x in the plate width direction as a variable.

T (x) = b ₁ x ⁴ + b ₂ x ³ + b ₃ x ² + b ₄ x + b ₅ (4) where −1 ≦ x ≦ 1, x = −1: plate end position of the drive side plate x = 1: Plate end position of plate on the work side side The coefficients b _{1 to} b _{5 in} the equation (4) are obtained by detecting the temperature distribution in the plate width direction by the plate temperature detector and performing multiple regression. It is desirable that the expression representing the plate temperature T (x) is of the fourth order or higher for x from the viewpoint of accuracy.

The shape (steepness) distribution at normal temperature is estimated as follows.

First, a slit model (see FIG. 5) in the case where the temperature difference is not considered in the sheet width direction using Equation (1) is considered.

Each slit length l (x) at the time of no tension is given by the following equation from the equation (1).

l (x) = (1 ± λ 2 (x) · π 2/4) l.

However, +: λ (x) ≧ 0, −: λ (x) <0 Here, temperature correction is performed on each slit length when there is no temperature difference in the plate width direction. That is, l ′ (x) = l (x) {1−β (T (x) −T ₀ )} (5) β: coefficient of linear expansion, T ₀ : room temperature (T (x)> T ₀ ) From equation (5), if min (l ′ (x)) = l ′ _min ,
The distribution of the difference in elongation Δε _i is obtained from the following equation (6).

Δε _i (x) = (l ′ (x) −l ′ _min ) / l ′ _min (6) Therefore, when there is a temperature distribution (T (x)) and a steepness distribution (λ (x)) The steepness distribution λ ′ (x) when the plate is cooled to room temperature is represented by Expression (7).

Since the equation (7) is not a quartic equation like the equation (1), it is rewritten into the following quartic equation.

_{λ "(x) = c 1} x 4 + c 2 x 3 + c 3 x 2 + c 4 x + c 5 above coefficients c ₁ to c ₅ of formula is obtained by performing multiple regression using equation (7).

Further, similarly to the equation (2), λ _s ′ (x) = c ₁ x ⁴ + c ₃ x ² + c ₅ λ _a ′ (x) = c ₂ x ³ + c ₄ x Ask for.

 The calculation of the shape correction amount is as follows.

The shape target _{λ 2 ', λ 4',} λ 1 ', λ 3' with respect to ^{_{λ 2 *, λ 4 *,}} λ 1 *, correction amount and a lambda ₃ ^* becomes Equation (8).

Δλ ₁ = λ ₁ ′ −λ ₁ ^* Δλ ₂ = λ ₂ ′ −λ ₂ ^* Δλ ₃ = λ ₃ ′ −λ ₃ ^* Δλ ₄ = λ ₄ ′ −λ ₄ ^* (8) Therefore, Δλ ₁ . What is necessary is just to operate each shape operation end so that (DELTA) (lambda) ₄ becomes zero.

 The correction amount of each shape operation end is as follows.

Δλ _i = f _{i1 Δδ BUR1} + f _{i2 Δδ BUR2} + f _{i3 Δδ BUR3} + f _{i4 Δδ BUR4} + f _{i5 Δδ BUR5} + f _{i6 Δδ sws} + f _{i7 Δδ SDS} + f _i8 ΔF _ws + f _i9 ΔF _DS ... 4, f _ij = C _i1 W ² + C _i2 W + C _{i3 where} C _ij : constant _Δδ BUR1 to _{Δδ BUR5} : pushing change amount of the first to fifth divided backup roll bearings _{Δδ sws} , _{Δδ SDS} : intermediate between work side and drive side Roll shift change amount ΔF _ws , ΔF _DS : Intermediate roll bender change amount on work side and drive side The constant of equation (9) is determined by multiple regression using an experiment in advance.

From equation (10), there are nine independent variables and four dependent variables, so a solution can be obtained by selecting four independent variables and solving the equation. If the previously selected solution exceeds the maximum value of the shape operation amount, select a value to about 80% of the maximum value of the previously selected shape operation amount, and change four of the remaining five independent variables. A solution can be obtained by selecting and solving the equation.

Next, an experimental example of the above-described rolling equipment and shape control using a model formula will be described.

1) Roll configuration of rolling mill Work roll: diameter 50mm x body length 400mm Intermediate roll: diameter 75mm x body length 400mm Central backup roll: diameter 120mm x body length 400mm (6
Split) Side backup roll: 120mm diameter x 400mm body length
(5 divisions) 2) Shape control end Intermediate roll bender: max 5ton / Chock Intermediate roll shifter: ± 40mm adjustable, see Fig. 2 for taper size Side split backup roll: Roll eccentricity ± max 0.
5mm adjustable 3) Experimental conditions High-frequency heating device: Heats strip at the entry side of rolling mill Temperature measuring roll: Thermocouple type (See Fig. 4) Shape detector: Magnetostrictive shape detector Strip: Material SUS430 Sheet thickness: 1.0mm , plate width: 350 mm, coils (annealed material) rolling lubrication: 40 ° C. of mineral rolling lubricating oil, 10% emulsion rolling reduction: 30% front tension: 30 kgf · mm ^-2 rear tension: 25 kgf · mm ^-2 rolling speed: 100m min- ¹ inlet side plate temperature: 400 ° C (center) As a result of the experiment under the above conditions, the following became clear.

The temperature distribution was given in a parabolic pattern at 50 ° C, 80 ° C, and 100 ° C in the strip width direction (the strip temperature was high at the center), and the shape on the exit side of the rolling mill was controlled flat. As a result, in the case of the conventional method, the plate shape after cooling was steepness 1.0%, 1,3%, 1.5%. On the other hand, in the present invention, the plate shape after cooling is about 0.6 each.
%.

The present invention can be applied not only to the above-described 12-stage cluster rolling mill but also to all rolling mills having four or more shape operation ends including the shape operation ends of the work side and the drive side.

[Effects of the Invention] In the present invention, the shape distribution in the sheet width direction at room temperature is estimated based on the sheet temperature distribution and the sheet shape distribution in the sheet width direction detected on the exit side of the rolling mill, and the estimated shape distribution and the model formula Then, the shape operation amount is obtained from the above, and the shape operation end is controlled. Therefore, shape defects such as ear waves and middle elongation that have occurred in a high temperature state disappear by thermal deformation while cooling to room temperature. As a result, a good plate shape can be obtained, and the yield can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a plate rolling facility for implementing the shape control method of the present invention, FIG. 2 is a detailed view of an intermediate roll of the cluster rolling mill shown in FIG. 1, and FIG. Detail of side backup roll of machine, 4th
The figure is a detailed view of the temperature detecting device shown in FIG. 1, and FIG. 5 is an explanatory view of a slit model. 11 …… Cluster rolling mill, 12 …… Work roll, 13 ……
Intermediate roll, 16 Central backup roll, 17 Side backup roll, 21 Intermediate roll bender,
22: Intermediate roll shift device, 23: Split backup roll pushing device, 25: Temperature detection device, 26: Hollow roll, 27: Thermocouple, 31: Control operation device, 37: Controller.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-207909 (JP, A) JP-A-3-126207 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21B 37/28-37/44

Claims (1)

(57) [Claims] 1. A model formula indicating a relationship between a shape distribution in a sheet width direction and a shape manipulation amount is obtained in advance, and a shape distribution in a sheet width direction is detected at an outlet side of a rolling mill. In the shape control method of calculating the shape operation amount from the model formula and controlling the shape operation end based on the obtained shape operation amount, the temperature distribution in the sheet width direction on the exit side of the rolling mill together with the shape distribution in the sheet width direction. These are approximated by a fourth or higher-order equation relating to a variable x indicating the position in the sheet width direction, and the shape distribution in the sheet width direction at normal temperature is estimated based on the approximation formula. A shape control method in sheet rolling, wherein a shape manipulation amount is obtained from the following.