JPS6134883B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a strip shape control method for a six-layer rolling mill having intermediate rolls movable in the axial direction of the rolls. It is known that a six-layer rolling mill with intermediate rolls has excellent shape control performance. However, in order to take full advantage of this performance, the intermediate roll position and roll bending pressure must be set to appropriate values in the initial settings. However, it is not easy to set these two values to appropriate values at the same time, and until now, operators have been content with setting them based on their experience, and sometimes large shape defects have occurred due to incorrect settings. In view of these problems, the present invention provides an initial rolling setting method for a 6-layer rolling mill in which the intermediate roll position and roll bending pressure are set to optimal values, and a uniform shape in the width direction can be produced. be. The gist is that the strip shape elongation pattern in the strip width direction of the pre-rolled material is expressed by a quartic function at the end of rolling of the pre-rolled material using a 6-layer rolling mill with intermediate rolls movable in the roll axis direction. Using the shape detection parameters, the rolling actual values of the intermediate roll position and work roll bending pressure at that time, and the shape influence coefficient on the intermediate roll position and roll bending pressure obtained from the shape parameters and rolling actual values of the preceding rolled material. , the shape parameters are estimated when the intermediate roll position and roll bending pressure are changed from their actual values, and the correction amount of the intermediate roll position and roll bending pressure is calculated so that the shape parameter estimated value comes closest to the shape parameter target value. The optimum set values for the intermediate roll position and roll bending pressure of the preceding rolled material are determined, and these optimum set values are stored by dividing them into the relationships of steel type - plate width - plate thickness or rolling reduction. The initial setting values for the roll position and roll bending pressure are determined by searching the stored values under these rolling conditions, which is the initial setting method for the six-layer rolling mill. The present invention will be described in detail below with reference to the drawings. Figure 1 shows a 6-layer rolling mill, where 1 is the rolled material, 2 and 2' are work rolls, 3 and 3' are intermediate rolls that can be moved in the roll axis direction, and 4 and 4' are back-up rolls. It is. That is, the rolled material 1 is rolled by the upper and lower roll groups while its shape is corrected by the moving positions of the intermediate rolls 3, 3'. FIG. 2 illustrates the initial setting method of the present invention applied to the six-layer rolling mill of FIG. 1. 5 is an intermediate roll position detector, and a synchro electric machine is used. 6 is a work roll bending pressure detector. The work roll bending pressure detector 6 measures the bending pressure applied to both ends of the work roll 2. A shape detector 7 measures the strip shape elongation rate in the width direction of the rolled material 1 and sends it to the shape parameter converter 8. The shape parameter conversion device 8 converts the shape elongation rate signal in the strip width direction into a fourth-order polynomial y=λ ₀ +λ ₁
+λ ₂ x ² +λ ₃ x ³ +λ ₄ x ⁴ , and among the coefficients of the polynomial, the coefficients λ ₂ and λ ₄ representing components symmetric with respect to the plate center are linearly transformed to obtain the symmetric component shape parameter Λ ₂ , Λ ₄ and coefficients λ ₁ and λ ₃ representing asymmetric components are linearly transformed to obtain asymmetric component shape parameters Λ ₁ and Λ ₃ . The specific conversion formula for the shape parameters (Λ ₁ , Λ ₂ , Λ ₃ , Λ ₄ ) is as follows:

[Formula] is used. 9 is a device for calculating the shape influence coefficient of the intermediate roll position and roll bending pressure during rolling of the preceding rolled material. The shape influence coefficient represents the degree of influence that a unit change in intermediate roll position or roll bending pressure has on a change in shape parameter. The shape influence coefficients β ₁₁ and β ₁₂ of the bending pressure Q and the intermediate roll position δ with respect to the symmetrical component shape parameter Λ ₂ are as follows. β ₁₁ =∂Λ ₂ /∂Q, β ₁₂ =∂Λ ₂ /∂δ Further, the shape influence coefficients β ₂₁ and β ₂₂ of Q and δ with respect to the symmetrical component shape parameter Λ ₄ have the following meanings. β ₂₁ = ∂Λ ₄ / ∂Q, β ₂₂ = ∂Λ ₄ / ∂δ The shape influence coefficient during rolling of the preceding rolled material is determined by applying the approximate value of the coefficient given before the start of rolling to the roll bending during rolling. It can be determined by modifying the pressure, the amount of operation of the intermediate roll position, and the amount of shape change in response thereto. The specific method is β ₁₁ ,
This will be explained using β ₁₂ as an example. The estimated values of the shape influence coefficient at a certain rolling point are β ₁₁ (t) and β ₁₂ (t). If the shape parameter Δ ₂ changes by ΔΛ ₂ when the roll bending pressure and intermediate roll position are manipulated by ΔQ and Δδ, respectively, up to the next point in time, the shape influence coefficient is corrected using the following equation. β ₁₁ (t+1)=β ₁₁ (t)+k ₁ (t)・(ΔΛ ₂ −β ₁₁ (t)ΔQ−β ₁₂ (t)Δδ) β ₁₂ (t+1)=β ₁₂ (t)+k ₂ (t )・(ΔΛ ₂ − β ₁₁ (t) ΔQ−β ₁₂ (t) Δδ) k ₁ (t), k ₂ (t) are disturbances included in the actual measured value of Λ ₂ (for example, changes in the shape of the strip original plate or shape detection) This is a coefficient that is corrected as the rolling progresses, based on the statistical value of the amount of variation due to changes in the rolling conditions (variations in the output value of the rolling machine) and changes in the rolling conditions of the shape influence coefficient. Reference numeral 10 denotes an optimum setting value calculation device for rolling the pre-rolled material. The optimum setting value calculation device 10 calculates the shape parameter value of the previously rolled material, the roll bending pressure at that time, the actual value of the intermediate roll position, and the shape influence coefficient on the roll bending pressure and intermediate roll position of the previously rolled material calculated in step 9. Calculate the amount of correction of the roll bending pressure and intermediate roll position so that the shape parameter approaches the target value given by 11 from the actual value using Find the optimal setting value for the position. The optimum setting value is calculated as follows. Expected shape parameter values A ^s ₂ , Λ ^s ₄ when the intermediate roll position and roll bending pressure are changed Δδ, ΔQ from the actual rolling values δ゜, Q゜ of the preceding rolled material
can be calculated as Λ ^s ₂ = Λ ₂ ° + β ₁₁ ΔQ + β ₁₂ Δδ Λ ^s ₄ = Λ ₄ ° + β ₂₁ ΔQ + β ₂₂ Δδ, _where Λ 2 ° and Λ ₄ ° are the actual rolling shape parameter values of the previously rolled material. The closeness between the parameter value and shape parameter target values ₂ and ₄ is evaluated using the following equation. J = J (Λ ^s ₂ , Λ ^s ₄ , ₂ , ₄ ) The value of J is the most optimal Δδ and ΔQ within the allowable range of Δδ and ΔQ as the intermediate roll position and roll bending pressure set value correction amount. shall be. That is, the optimal setting values for both operating ends when rolling the pre-rolled material are as follows: δ=δ°+Δδ, Q=Q°+ΔQ. In the example, P ₁ ~ on the δ-Q plane in FIG.
Find the shape parameter value when changing the setting of δ and Q at the Pn position, J = ( ₂ - Λ ^s ₂ ) ² + ( ₂ Λ ^s ₄ ) ² + W・(Λ
^s ₄ Λ
^s ₂ ) However, W = 10.0 Λ ^s ₄ > Λ ^s ₂ { 0.0 Λ ^s ₄ ≦Λ ^s ₂ The closeness to the shape parameter target value is evaluated using the evaluation function, and at the point Pi where the evaluation value is the minimum, Let δ and Q be the optimal setting values. Reference numeral 11 denotes a device for instructing target values of shape parameters of the pre-rolled material. 12 stores the optimum setting values of the intermediate roll position and roll bending pressure in the rolling of the preceding rolled material obtained in 10 in the optimum setting value storage section divided by the rolling conditions of the relationship between steel type - plate width - plate thickness or rolling reduction. The initial setting of the intermediate roll position and roll bending pressure for the next rolling material is a device that searches the storage section based on the rolling conditions in that case to find the optimal setting values. In the example, in the rolling condition classification of the preceding rolled material
The optimal setting values δ and Q calculated in step 10 are changed to the optimal setting values δ ^* and Q ^* that were previously stored in that condition category.
Instead, instead of storing it as is, δ _N = α・δ + (1 − α) δ ^* Q _N = α・Q + (1 − α) Q ^* α is δ modified using the above formula, which is a constant given in advance. _N , Q _N is paid. FIG. 4 shows an example of the contents of the optimum setting value storage section. 13 is a roll bending device provided at both ends of the work roll, and 14 is an intermediate roll position shifting device. Both devices set the roll bending pressure and intermediate roll position to the optimum initial setting values determined in step 12. The present invention (1) eliminates the need to create model formulas that relate shape parameters and rolling conditions, and (2) stores optimal setting values for intermediate roll positions and roll bending pressures divided by appropriate rolling conditions. The system is characterized in that a section is automatically created using actual values, and initial settings are performed based on the stored contents. As described above, according to the present invention, the optimal initial setting values for the intermediate roll position and roll bending pressure of the 6-layer rolling mill are automatically calculated, and a strip having a good shape can be rolled immediately from the start of rolling. This greatly contributes to improving the efficiency of rolling operations and the quality of rolled products.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a six-layer rolling mill to which the present invention is applied. FIG. 2 is a block diagram showing an outline of an apparatus for carrying out the method for initializing the intermediate roll position and roll bending pressure of the present invention. Further, FIG. 3 is a contour map of shape evaluation values on the δ-Q plane, and FIG. 4 is an explanatory diagram showing the contents of the intermediate roll position and roll bending pressure optimum setting value storage unit. 1: Rolled material, 2, 2': Work roll (work roll), 3, 3': Intermediate roll, 4, 4': Backup roll (reinforcement roll), 5: Intermediate roll position detector, 6: Work roll Bending pressure detector, 7: Shape detector, 8: Shape parameter conversion device, 9: Previously rolled material shape influence coefficient calculation device, 1
0: Pre-rolled material optimum setting calculation device, 11: Pre-rolled material shape parameter target value indicating device, 12: Intermediate roll position, roll bending pressure optimum setting value storage unit writing/reading device, 13: Work roll bending device, 14 : intermediate roll position shift device,
P ₁ to Pn are set point change points, Pi is optimal set point.

Claims (1)

[Claims] 1. A shape detection parameter that indicates the strip shape elongation rate pattern in the plate width direction of the previously rolled material as a quartic function at the end of rolling of the previously rolled material in a six-layer rolling mill having intermediate rolls movable in the roll axis direction. , using the actual rolling values of the intermediate roll position and work roll bending pressure at that time, and the shape influence coefficients for the intermediate roll position and roll bending pressure obtained from the shape parameters and rolling actual values of the preceding rolled material. Then, the shape parameters are estimated when the roll bending pressure is changed from its actual value, and the intermediate roll position and the correction amount of the roll bending pressure are determined so that the shape parameter estimated value comes closest to the shape parameter target value, and the preliminary rolling is performed. The optimum setting values for the intermediate roll position and roll bending pressure of the material are determined, and these optimum setting values are stored in the relationship of steel type - plate width - plate thickness or rolling reduction, and the intermediate roll position and roll bending pressure of the next rolled material are determined. An initial rolling setting method for a six-layer rolling mill, characterized in that the initial setting value of bending pressure is determined by searching the stored value under the rolling conditions.