JPH0455006A - Control method for plate thickness and flatness in reverse rolling - Google Patents

Abstract

PURPOSE:To remarkably improve the accuracy for controlling plate thickness and flatness by deriving a coefficient for showing the influence exerted on plate thickness and a plate crown by a variation of a surface profile of a rolling roll, inputting the coefficient into a plate thickness prediction model expression and a plate crown prediction model expression, executing the plate thickness control, and also, executing the flatness control. CONSTITUTION:An arithmetic unit 20 calculates a roll center crown and a surface shape influence coefficient by using an expression from the previous pass or a rolling load inputted at the time of rolling a thick plate 10 in the previous time, and measured values of plate thickness and a plate crown. The calculated roll center crown, etc., are transferred to a host process computer 22, and the process computer 22 reflects a result of this calculation on a model expression of the expression, and executes a rolling reduction schedule calculation of the next pass and thereafter, or the thick plate 10 which is rolled in the next time. Accordingly, the thick plate 10 whose plate thickness accuracy and flatness are satisfactory can be rolled.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling plate thickness and flatness in reverse rolling such as thick plate rolling.

[Conventional technology]

In general, in plate rolling, elastic elongation of the rolling mill due to rolling reaction force, amount of roll wear during rolling, heat crown (
Amount of crown that occurs due to temperature increase due to heat of rolled material during rolling)
The reduction schedule is determined by considering the following. When determining the reduction schedule, for example,
139862 and 61-95709, a method is generally adopted in which the plate thickness and flatness are controlled at the same time by keeping the plate crown ratio change within a predetermined tolerance in each pass. Model formulas used to calculate the rolling reduction schedule include a plate thickness prediction model formula for predicting plate thickness and a plate crown prediction model formula for predicting plate crown. In these model formulas, the amount of crown at the center of the roll is used as the amount of crown at the center of the roll because heat crown and roll wear occur more frequently at the center of the roll axis. Further, the amount of roll wear and the amount of heat crown are generally determined using predicted values based on model formulas, and a prediction model is used that takes into account the shape of the rolled material up to the time of rolling, the history of rolling conditions, etc. Here, when the surface profile in the roll axis direction changes, the effect of that change on the plate thickness and plate crown is explained in the third section.
In this case, the entrance and exit side plate thicknesses are 30 mm as shown in Figures and Figure 4.
in, 24μl, plate width 4000μm, rolling pressure i to
n, and the surface profile shows the relationship between the roll crown, roll deformation, and plate crown for various cases such as the sinusoidal leap number.As is clear from these figures, even if the crown at the center of the roll is the same, , plate thickness and plate crown are changing significantly due to the development of surface profile. Therefore, it is difficult to accurately predict the plate thickness and plate crown based only on the amount of crown at the center of the roll.

[Problem to be solved by the invention]

However, the conventional model formula does not take into account the fact that changes in the surface profile affect the predicted plate thickness and plate crown amount. Since prediction errors in plate thickness and plate crown may occur, there is a problem in that conventional techniques cannot adequately control plate thickness and flatness. In addition, in the past, even if an attempt was made to reflect the surface profile in determining the reduction schedule, the accuracy of predicting the surface profile was low, and this decrease in prediction accuracy meant that the plate thickness and flatness could not be accurately reflected to accurately reflect the surface profile. This was a major factor hindering the realization of temperature control. On the other hand, a method that can be considered is to actually measure the surface profile online and reflect it in the model formula for the crown amount of the plate, but a sensor that can accurately measure the surface profile in the adverse environment near the hot rolling mill. The reality is that there is no surface profile, and the above problem cannot be solved by actually measuring the surface profile. The present invention was made to solve the above-mentioned conventional problems, and makes it possible to accurately predict the influence of the roll profile that changes during rolling on the plate thickness and plate crown, and improve the plate thickness and flatness. An object of the present invention is to provide a method for controlling plate thickness and flatness in reverse rolling, which can significantly improve control accuracy.

[Means to solve the problem]

When performing reverse rolling such as thick plate rolling, the present invention detects the plate thickness and plate crown of the rolled material before rolling or before passing, and uses the detected plate thickness and plate crown to change the surface profile of the rolling roll. Calculate the coefficients representing the influence of the influence on plate thickness and plate crown, incorporate the coefficients representing the determined effects into the plate thickness prediction model formula and plate crown prediction model formula, and perform plate thickness control according to the plate thickness prediction model formula. The above problem is solved by performing flatness control according to the plate crown prediction model formula.

[Effect]

As shown in Figures 3 and 4 above, the influence of the surface profile of the roll on the plate thickness and plate crown is determined by the difference in diameter between the roll center and the roll end (roll center crown).
In addition, the surface profile of the roll is a major factor. The roll surface profile is determined by the superposition of the roll's initial crown, roll wear profile, and heat crown, and therefore changes significantly over the course of rolling. From the above viewpoint, the inventor conducted various simulations regarding parameters representing the influence of changes in roll surface profile on plate thickness and plate crown. In this case, the evaluation parameter is defined as the surface shape influence coefficient ΔV of the ratio (A+/Ao) between the roll surface shape AO before the change and the roll surface shape A+ after the change, as shown in FIG. By incorporating this surface shape influence coefficient ΔVo into the plate thickness prediction model and the plate crown prediction model, it is possible to improve the plate thickness accuracy in rolling and the flatness control accuracy of the constant crown ratio method. The plate thickness prediction model formula incorporating the surface shape influence coefficient ΔvO as described above is shown in the following formula (1), and the plate crown prediction model formula is shown in the following formula (2). H=S+ 11(P, Pa) 10a+ ・8Cw+
a2ΔVO・・・・・・・・・(1) However, H: outlet plate thickness, S: set opening degree, f: deformation of mill due to load, P
: Rolling load, Po: Calibration load, ΔCW:
Amount of change in roll center crown, al, al: coefficient. cr = llh (P) + I;12 (
Cp) + b 1xcw+b2・Δ■0 ・・
・・・・・・・・・(2) However, C": Exit side plate crown, I
; Jl: Roll deformation due to load, g2: Influence equation of entrance plate crown, Cw: Roll center crown, bt, bz
: is a coefficient. The accuracy of the roll center crown change amount ΔCw, roll center crown Cm, and surface shape influence coefficient Δ■0 in the above model formulas (1) and (2) depends on the prediction accuracy of the heat crown and roll wear profile. ing. Therefore,
In order to improve the prediction accuracy of model formulas (1) and (2), the following formulas (3) to (5), which are a combination of formulas (1) and (2), are used to calculate rolling performance data, plate thickness, and plate crown measurement data. ), the amount of change in the center crown of the roll ΔCW
, roll center crown Cm, and surface shape influence coefficient ΔVO are calculated. That is, the rolling load for each rolling pass or each slab is Pi, the entrance plate crown is Cpi, the initial crown is CWO1 plate thickness, and the actual values of the plate crown are Ha and c.
If ra is the change amount ΔCw of the roll center crown
, roll center crown CW, and surface shape influence coefficient ΔVo are calculated using the following formulas (3) to (5) % formula % )] )] Into these formulas (3) to (5), enter each actual measured value such as rolling load Pi, etc. The determined roll center crown change amount ΔCW, roll center crown Cw, and surface shape influence coefficient ΔVo are calculated from (1) above.
By substituting the plate thickness prediction model formula and plate crown prediction model formula in Equation (2), the surface shape influence coefficient estimated from the most recent rolling data, that is, the parameter representing the roll profile, can be used as the plate thickness prediction model formula and plate crown prediction model formula. It can be incorporated into the crown prediction model formula. Therefore, the roll surface profile that affects plate thickness and plate crown can be reflected in the predictive model formula. The present invention has been made based on the above findings.According to the present invention, it is possible to accurately predict the influence of the roll surface profile that changes during rolling on the plate thickness and plate crown. Therefore, the accuracy of predicting the plate thickness and plate crown, as well as the control accuracy, can be greatly improved.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. This embodiment is a system for controlling the thickness and flatness of a thick plate by implementing the present invention when rolling a thick plate in a reverse rolling mill configured as shown in FIG. In FIG. 1, numeral 10 is a thick plate, and 12 is a work roll for rolling the thick plate. A backup roll 14 is provided above and below the work roll 12 for pinching the work roll from above and below. Further, this backup roll 14 is provided with a load cell 16 for detecting rolling load. Further, reference numeral 18 is a plate thickness and plate crown measuring device for measuring the plate thickness and plate crown of the thick plate 10, and is provided in the vicinity of the rolling mill. The rolling load detected by the load cell 16 and the plate thickness and plate crown detected by the plate thickness and plate crown measuring device 18 are input to the calculation device 20. The calculation device 20 calculates the roll center crown change amount ΔCm, the roll center crown Cw, and the surface shape influence coefficient Δvo based on the input plate thickness, plate crown, and rolling load. Further, reference numeral 22 stores a reduction schedule,
This is a process computer that controls the entire rolling process. The surface shape influence coefficient ΔVO, etc. determined by the arithmetic unit 20 are input into this rolling down schedule and reflected in the rolling down schedule. The effects of the embodiment will be explained below. The calculation device 20 uses the above formulas (3) to (5) from the rolling load P input when the thick plate 10 was rolled in the previous pass or the previous time, and the measured values of the plate thickness H and plate crown Cw. , roll center crown Cw, surface shape influence coefficient ΔVO
Calculate. The calculated roll center crown Cw, etc. is transferred to the higher-level process computer 22, and the process computer 22 reflects this calculation result in the model formulas of equations (1) and (2) above, and calculates the results for the next pass and subsequent passes. Alternatively, calculate the rolling reduction schedule for the next rolling thickness [10]. Therefore, in rolling reduction schedule calculation, it is possible to determine the rolling schedule by accurately evaluating the influence of changes in the roll surface profile on the plate thickness and plate crown, and to roll the thick plate 10 with good plate thickness accuracy and flatness. becomes possible. In addition, in the above example, the present invention was implemented when rolling a thick plate with a four-layer reverse rolling mill, but the rolling mill on which the present invention can be implemented is not limited to the one shown in the figure. However, the effects of the present invention can be similarly obtained with other rolling mills such as Type 61. [Effects of the Invention] As described above, according to the present invention, it is possible to accurately predict the effect of the roll surface profile that changes during rolling on the sheet thickness and sheet crown, and to reflect this in the rolling schedule. Therefore, the accuracy of plate thickness and flatness control can be greatly improved, so it is possible to prevent downgrading due to errors in predicting plate thickness, and it is also possible to reduce the load on the finishing process due to poor flatness. In addition, the roll chance of the rolling process, which has conventionally been limited from the viewpoint of flatness control, can be expanded or relaxed, and excellent effects such as simplification of material distribution can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram including a partial view showing the configuration of a plate thickness and flatness control system according to an embodiment of the present invention. FIG. 2 is a roll profile for explaining the present invention in detail. Figure 3 is a sectional view of main parts showing an example of changes in roll profile, W& diagram showing an example of the effect on plate thickness and plate crown when the roll profile changes, and Figure 4 is an example of another effect. FIG. 22...Process computer.

Claims (1)

[Claims] (1) When performing reverse rolling such as thick plate rolling, the plate thickness and plate crown of the rolled material are detected before rolling or before the pass, and the detected plate thickness and plate crown are used to detect changes in the surface profile of the rolling roll. Find the coefficients that represent the influence on plate thickness and plate crown, incorporate the calculated coefficients into the plate thickness prediction model formula and plate crown prediction model formula, and perform plate thickness control according to the plate thickness prediction model formula. A method for controlling plate thickness and flatness in reverse rolling, characterized in that the flatness is controlled in accordance with the plate crown prediction model formula.