JPH0685930B2 - Plate thickness control method in rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) Regarding the sheet thickness control in a rolling mill, in this specification, in the sheet thickness control of a rolling mill using a gauge meter type, an error caused by a roll profile change is determined from a roll profile. By reducing with the correction factor determined,
We propose the results of the development research on the improvement of the delivery side plate thickness accuracy.

The gauge thickness control in the rolling mill is generally performed by the following equation (1).

H = S + f ₁ (P) −f ₁ (P ₀ ) + f ₂ (P, D _W , D _B , H ₁ , W) −f ₃ (P ₀ , D _W , D _B ) −ΔCr ……… (1 ) H: Thickness of exit side S: Roll opening f ₁ : Housing characteristic formula f ₂ : Roll deformation formula for rolling f ₃ : Roll deformation formula for kiss roll P: Rolling load D _W : Work roll diameter D _B : Backup roll diameter H ₁ : Input side plate thickness W: Plate width P ₀ : Zero adjustment load ΔCr: Increment of work roll crown from zero adjustment (conventional technology) Roll wear during rolling, influence of roll profile that changes due to heat crown Is only reflected in the term of ΔCr at the end of the right side of the formula (1) as a conventional increment of crown amount, or is only considered as a function of the center Cr, and the shape in the roll cylinder length direction is not reflected. .

In other words, if the Cr content was the same in each of the different roll profiles, the effect was treated equivalently regardless of the roll profile.However, according to the simulation, even if the Cr content is the same, the roll deflection and flatness are different. And the Cr content is treated equivalently regardless of the roll flow rate, which deteriorates the delivery side plate thickness accuracy.

(Problems to be solved by the invention) In the conventional gauge meter system, accuracy is good immediately after roll change, that is, when the roll profile is not largely changed, but as described above, as the number of rolling increases, There is a drawback that the profile is changed and the delivery side plate thickness accuracy is deteriorated. Therefore, in the present invention, by applying an appropriate correction according to the roll profile to the gauge meter type, the error of the gauge meter type caused by the roll profile change is caused. It is an object of the present invention to provide a plate thickness control method capable of advantageously reducing

(Means for Solving Problems) The present invention is for controlling the plate thickness in a rolling mill, and includes a term of roll opening, a term of housing characteristic equation, a term of roll deformation equation during rolling and kiss roll, and Using the gauge meter formula that is related to the correction term of the work roll crown increment from the time of zero adjustment, determine the rolling position from the rolling conditions, and set the rolling mill to this rolling position to perform rolling. Measure the roll profile that changes in the middle with a roll profile detector or predict it with a roll profile prediction formula such as a roll wear formula. Incorporate a parameter representing the influence of this roll profile over time into the term of the roll deformation formula. It features a combination of calculating and adjusting the reduction position based on a gauge meter formula that takes into account the influence of the roll profile. A thickness control method in that the rolling mill.

Now, the gauge meter type of the flat roll of the 4-high rolling mill is
It can be expressed as the following equation (2).

H = S + f ₁ (P) −f ₁ (P ₀ ) + {f ₂₁ (P, D _W , D _B , H ₁ , W)
+ F ₂₂ (P, D _W , D _B , H ₁ , W) + f ₂₃ (P, D _W , D _B , H ₁ , W)}-{f ₃₁ (P ₀ , D _W , D _B ) + f ₃₂ ( P ₀ , D _W , D _B ) ＋ f ₃₃ (P ₀ , D _W , D _B )}-ΔCr ……… (2) f ₂₁ : Deflection formula of backup roll during rolling f ₂₂ : Work roll during rolling Flat type of backup roll f ₂₃ : Flat type of work roll and rolled material during rolling f ₃₁ : Deflection type of backup roll during kiss roll f ₃₂ : Flat type of work roll and backup roll during kiss roll f ₃₃ : Flat type between work rolls during kiss roll However, the roll is not flat due to the effects of initial crown, roll wear, and heat crown. Therefore, the effect of the roll profile is also taken into consideration to improve the accuracy of the gauge meter formula, and the structure of the formula is as shown in formula (3).

H = S + f ₁ (P) −f ₁ (P ₀ ) + {f ₂₁ (P, D _W , D _B , H ₁ , W, α ₂₁ ) + f ₂₂ (P, D _W , D _B , H ₁ , W , α ₂₂ ) + f ₂₃ (P, D _W , D _B , H ₁ , W, α ₂₃ )}-{f ₃₁ (P ₀ , D _W , D _B , α ₃₁ ) + f ₃₂ (P ₀ , D _W , D _B , α ₃₂ )} + f ₃₃ (P ₀ , D _W , D _B , α ₃₃ )}-ΔCr ……… (3) α ₂₁ : Parameter that represents the influence of the roll profile on the roll deflection during rolling. α ₂₂ : Parameter indicating the effect of roll profile on the flatness of WR and BUR during rolling α ₂₃ : Parameter indicating the effect of roll profile on the flatness of WR and rolled material α ₃₁ : Roll during kiss roll Parameter showing the influence of roll profile on the deflection of the roll α ₃₂ : Parameter showing the influence of roll profile on the flattening of WR and BUR during kiss roll α ₃₃ : Roll profile for flattening between WR during kiss roll The parameters α _{21 to} α ₂₃ representing the influence of the feel are values determined by the roll profile during rolling, and α _{31 to} α ₃₃ are values determined by the roll profile during kiss rolling.

In the equation (3), f ₁ , f ₂₁ , f ₂₂ , f ₃₁ , f ₃₂ , and f ₃₃ are simulations or experimentally derived functions.

Now, as shown in FIG. 1, the rolling position 6 is calculated by using the gauge meter formula 5 of the formula (3) that incorporates the predicted rolling load 1, the entrance side plate thickness 2, the roll profile 3 and the exit side plate thickness 4 as rolling data. The rolling position 8 of the rolling mill 7 is set and rolling is performed.

When rolling is completed, actual rolling load 9 and actual reduction position 8
Then, the roll profile 10 is taken in as the data obtained by actually measuring or predicting the changing roll profile 10 by the measurement formula, and the gauge thickness of the output side 11 by the gauge meter formula 5 of the formula (3).
Is calculated and used as the information on the entrance side plate thickness of the next pass.

Here, as shown in FIG. 2, the parameter representing the influence of the roll profile 10 over time is a function of the deformation amounts x ₁ , x ₂ ... xi from the reference flat roll at the respective dividing point positions of the roll. .

The roll profile may be directly detected by a roll profile detection device or may be calculated by a roll friction type heat crown type.

(Operation) FIGS. 3 to 6 exemplify various different roll profiles, but any of them can be applied to the present invention. In these cases, regardless of each roll profile, the effect of roll profile, which changes due to roll wear and heat crown, was treated as equivalent if the amount of roll crown Cr was equal, but as a result of examination by simulation on this point According to the results, even if the Cr content is the same, the roll deflection and flattening are shown in Figs. 7 (a), (b),
The difference as shown in (c) is generated, which is a cause of deteriorating the accuracy of the delivery side plate thickness. On the other hand, improvement of the delivery side plate thickness accuracy can be achieved only by the measures according to the present invention.

(Example) For comparison, when rolling was performed using a gauge meter type without considering the roll profile, one roll chance (plate width 5000 to 2000 mm, 412 pieces, 4350 tons)
It was 10σ = 130 μm. The accuracy of 100 rolls after the start of rolling was 1σ = 107 μm, and the accuracy of the last 100 rolls was 1σ = 168 μm, and the precision deteriorated as rolling proceeded.

However, when the rolling according to the present invention is performed, the accuracy of the gauge of 1 roll chance (plate width 5000 to 2000 mm, 430 pieces, 4620 ton) is 1σ = 87 μm, and the accuracy of 100 pieces after the start is 1σ = 83 μm and the last 100 pieces. The accuracy was almost unchanged at 1σ = 89 μm.

(Effect of the Invention) In the conventional gauge meter type, even if the accuracy is high at the start of rolling, if the roll profile changes due to the effects of roll wear, heat crown, etc., the delivery side plate thickness accuracy has deteriorated.

However, in the present invention, since the roll profile change is taken into consideration, the precision deterioration due to the roll profile change does not occur, and a good plate thickness precision can always be obtained.

[Brief description of drawings]

FIG. 1 is a flow chart of a plate thickness control method according to the present invention, FIG. 2 is an explanatory diagram of a roll profile change amount, FIGS. 3 to 6 are various roll profile diagrams, and FIG. 7 is a roll profile. 6 is a chart showing the difference in roll deflection, the difference in flatness between WR and BUR, and the flatness between WR rolled materials.

Claims (1)

[Claims] 1. A roll opening term, a housing characteristic equation term, a roll deformation equation term during rolling and a kiss roll, and a work roll crown from the time of zero adjustment when controlling the plate thickness in a rolling mill. Using the gauge meter formula that is related to the increment correction term, determine the rolling position from the rolling conditions.When setting the rolling mill to this rolling position and rolling, the roll profile that changes during rolling is calculated. Measured with a detector or predicted by a roll profile prediction formula such as a roll wear formula.The effect of the roll profile was taken into consideration by incorporating the parameter showing the influence of this roll profile over time into the term of the roll deformation formula. A strip thickness control method in a rolling mill characterized by a combination of calculating and adjusting the reduction position based on a gauge meter type .