JPS63140717A - Method for controlling shape in cold rolling - Google Patents

Abstract

PURPOSE:To improve a shape at the tip part of a succeeding plate at the time when the kind of steel is changed by finding the set value of a bender pressure by a specific equation from a deviation value in the work roll benders at a work side and driving side of a final stand and a wedge amt. prior to rolling. CONSTITUTION:In the cold rolling mill enabling to set a bender pressure independently at a work side and driving side respectively, the respective set value of a bender pressure at a work side and driving side is calculated with the equation Pw=PB+1/2Pd, PD=PB+1/2Pd, PdPB{mXPd<-1>+nXf(td)}, Pd<-1>=Pw<-1>-PD<-1>, td=tw-tD from the deviation of the result value of the work roll benders at the work side and driving side of the final stand and the wedge amt. of the plate thickness prior to the rolling of a stock to be rolled [whereas, Pw, PD: bender pressures set value at work side and driving side, Pw, PD: bender pressures set value at work side and driving side, PB: the mean of set values, Pd; Difference in set values, Pd<-1>; Difference in the results values of the bender pressure of the preceding material, pw<-1>, PD<-1>; the result value of the bender pressure of the preceding material, td; the wedge amt. of the plate thickness prior to rolling, tw, td; the plate edge thickness prior to rolling and (m), (n); constant]. This set value is preset at the changing time of the steel kind and dimension of the stock to be rolled.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a shape control method in cold rolling, and relates to a cold rolling machine that automatically controls a work roll bending device that can be operated independently on the work side and drive side. This invention relates to a method of converting a hot-rolled steel strip after pickling into a flat cold-rolled steel strip using the detection output from a shape detector.

[Conventional technology]

A four-fold or six-fold rolling mill is generally used to cold-roll a cold-rolled steel strip, and this rolling mill is equipped with various shape control actuators in order to obtain a product with high flatness.

It is said that the final stand has a large influence on determining the shape of the final product, so a shape detector is usually installed on the exit side of the final stand, and the output of this detector is fed back to the shape actuator of the final stand to shape the final product. is under control. Further, changes in the steel type of the material to be rolled and presetting of changes in dimensions are carried out by calculating set values based on material information and rolling conditions.

By the way, when performing shape control on the rolling mill, the rolling balance between the working side and the driving side is disrupted, and one of the plate edges gradually begins to elongate, so in order to correct this, Control is often performed to create a difference between the bender pressures on the work side and the drive side (Japanese Patent Laid-Open No. 56-59525).

One of the major challenges in shape control technology is how to reset the bender pressure at the next change in steel type or dimension when there is a difference between the bender pressures on the work side and the drive side due to feedback control. It becomes. Generally, a method is adopted in which an average bender pressure setting value for the working side and the driving side is calculated by calculating based on material information and rolling conditions, and this is set as the bender pressure for the working side and the driving side.

(Problem to be solved by the invention) According to this method, the difference in bender pressure between the working side and the driving side is forcibly reduced at the setting change point at the joint between the leading plate and the trailing plate, as shown in Figure 1. The bender pressure changes rapidly because it is corrected to the same value. If this change is too rapid, troubles such as the plate being squeezed during rolling operation occur, causing great damage to the product and the rolling rolls. Even if no further trouble occurs, if feedback control is applied as it is, the difference in bender pressure will recover again, and it is not necessarily the appropriate setting to have the same value on the work side and drive side, and it is not a desirable setting method. This was also a problem.

It is an aim of the present invention to solve the above problems.

[Means for solving problems]

In other words, from the work roll bender pressure deviation value on the work side and drive side of the final stand and the pre-rolling thickness wedge of the material to be rolled, the bender pressure settings on the work side and drive side are calculated using the following formula. The value is preset at the point where the steel type or dimension of the rolled material changes.

PW = PB + − Pd ・−−−−−(1
) pO=pB −−Pd ・・・・・・(2
)Pd = FB (mXP,, 1 +nXf (t
d))・・・・・・ (3) td = tw −to −=
(5) PH=g (km, tfo, B, rf,
M) ...... (6) However, Pw: Work side bender pressure setting value 2 ports: Drive side bender pressure setting value PB: Average bender pressure setting value Pd: Difference between work side and drive side bender pressure settings Pd″″1:
Difference between actual bender pressure values on the working side and driving side for the preceding rolled material p w -1: Actual bender pressure value on the working side for the preceding rolled material P□-t, actual bender pressure value on the driving side for the preceding rolled material td: Before rolling plate Thickness wedge amount tw: Work side plate edge thickness before rolling to: Drive side plate edge thickness before rolling km: Deformation resistance value of rolled material t +o: Plate thickness at the entrance to the final stand B: Plate width rf: Final stand rolling car M: Final stand Index m indicating the rolling throughput from roll change: Rolling mill unbalance influence coefficient n: Rolled material unbalance influence coefficient.

(Operation) In equation (3), the function f(td) is generally a linear function and is given as follows.

f (td)=atd+b ”” (7)a,
b: Constant Also, the plate thickness measurement position for pw-1 and pd-1 is not at the true edge of the plate, but at a portion slightly closer to the center from the edge of the plate. This value is input to the calculator using the value determined from the output value of a plate thickness profile meter installed in the hot rolling or pickling process.

km, tfo, and rf in equation (6) are for determining the rolling load Pf at the final stand, and as shown in equation (8) below, klTl is originally a function specific to the material, and Pf=km (tfo, rf ) ・==−(
8).

M relates to the amount of thermal crown, and a prediction formula for the amount of thermal crown is applied.

By this method, when the bender differential pressure exceeds a certain allowable amount, steel melting is performed at the reduction position on the work side and drive side.

(Function) The difference in bender pressure between the working side and the driving side during rolling is due to the following:
As shown in FIG. 2, the difference in bender pressure is restored again by feedback control after the setting change, so it is presumed that this is due to an unbalance inherent in the rolling mill between the work side and the drive side.

Initial unbalance factors include unbalance inherent in the rolling mill and unbalance related to roll grinding. Moreover, as an unbalance that occurs over time, thermal unbalance due to the presence of a spindle on the drive side can be considered.

On the other hand, as an unbalance element of the material to be rolled, a difference in thickness (wedge) at the edge of the material plate before rolling can be considered.

The present invention calculates and sets the bender pressure settings on the work side and the drive side in consideration of the unbalance factors of both the rolling mill and the rolled material, thereby rationally improving the unbalance.

(Example) Fig. 1 shows an example in which the bender pressure on the drive side and the work side is set by adopting the setting method of the present invention. The difference in bender pressure is reflected in the settings of the trailing plate, and the settings are changed while maintaining the bender differential pressure Pd, eliminating sudden changes in bender pressure.
Moreover, the phenomenon that the bender differential pressure recovers due to feedback control is eliminated.

〔Effect of the invention〕

Since sudden changes in the bender differential pressure are eliminated, problems with squeezing during rolling are reduced.

Furthermore, since the unbalance elements on the work side and the drive side unique to the rolling mill are inherited, the bender pressure can be set more appropriately, and the shape of the leading end of the trailing plate is improved.

[Brief explanation of the drawing]

Fig. 1 is a chart showing an example in which bender pressures are determined and set independently for the work side and drive side according to the present invention, and Fig. 2 shows settings when the bender pressure settings for the work side and drive side are averaged and set. 7 is a chart showing how the bender pressure difference recovers due to a sudden bender pressure change at a change point and feedback control.

Claims (1)

[Claims] 1. Using a cold rolling mill having a work roll bending device that can be operated independently on the work side and the drive side, the deviation between the actual work roll bending pressure values on the work side and the drive side of the final stand and the From the pre-rolling thickness wedge of the material to be rolled, calculate the bender pressure setting values for each of the work side and drive side using the calculation formula below, and preset the setting values at the point where the steel type or dimension of the material to be rolled is changed. A shape control method in cold rolling characterized by the following. P_W=P_B+1/2P_d...(1) P_D=P_B-1/2P_d...(2) P_d=P_B{m×P_d^-^1+n×f(t_d
)｝...(3) Pd^-^d=P_W^-^1-P_D^-^1...
...(4) t_d=t_W-t_D...(5) However, P_W: Working side bender pressure setting value P_D: Drive side bender pressure setting value P_B: Average value of bender pressure setting value P_d: Working side bender pressure setting value Difference between set values of bender pressure on the working side and drive side P_d^-^1: Difference between actual bender pressure values on the working side and driving side of the preceding rolled material P_W^-^1: Actual value of bender pressure on the working side of the preceding rolled material P_D^- ^1: Actual value of bender pressure on the drive side of the preceding rolled material t_d: Plate thickness wedge amount before rolling t_W: Work side plate edge thickness before rolling t_D: Drive side plate edge thickness before rolling m, n: Constant