JPH0362482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tension control method for a tandem rolling mill.

[Conventional technology]

Conventionally, tension control of a rolled material in a rolling line has been constant tension control in which the roll speed and roll gap of a rolling mill are controlled so that the tension of the rolled material is equal to a set tension.

[Problem to be solved by the invention]

Therefore, in the rolled material controlled to a constant tension Ti, the hardness decreases in the part, that is, the skid mark part (the part where the temperature decreases during hot rolling → the crystal grains become coarse → the rolling load during cold rolling → When the plate thickness becomes thinner during cold rolling) is bitten by the rolls, the deformation resistance of the skid mark portion is small, so the rolling load changes from Pi shown in Figure 2a to Pir (<
Pi), and the deflection curve of the roll changes with this sudden change in rolling load, which causes the elongation rate of the rolled material to change in the width direction. There were problems in that accidents such as material getting caught in the rolls were likely to occur, and the rolling operation of the rolling mill became unstable, reducing productivity.

The present invention was made in order to solve the above problem, and analyzes the comprehensive processing external force that causes the rolled material to deform in the presence of tension, in other words, the deformation behavior of the rolled material in the presence of tension, By adding the tension during rolling as an external rolling force equivalent to the rolling load that contributes as an external force that deforms the rolled material, even if the rolling load suddenly changes, it can be recovered immediately and the rolling operation of the rolling mill can be continued. The purpose of the present invention is to provide a method for controlling the tension of a rolled material that can be stabilized.

[Means to solve the problem]

In order to achieve the above object, the present invention calculates the sum of the rolling load applied to the rolled material and the conversion value of the tension to the rolling load as an equivalent rolling external force in a cold tandem steel plate rolling line using a plurality of rolling mills. However, when the equivalent rolling external force fluctuates with respect to the standard equivalent rolling external force, the equivalent rolling external force fluctuation is calculated and the tension of the rolled material between the stands is controlled in response to this equivalent rolling external force fluctuation. .

[Effect]

In the present invention, the external force applied to the rolled material is converted into a load, and the total sum is calculated as the equivalent rolling external force, and when this fluctuates with respect to a preset reference equivalent rolling external force, a part of the fluctuation is applied to the tension control system. will be compensated for.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Figure 1, 1 and 1 are the work rolls of stand i-1, 2 and 2 are the back-up rolls, and 3
and 4 are roll gap control devices and load cells, respectively; 5 and 6 are roll speed control devices and tension detectors each including a roll drive motor; 7, 7
1 is a work roll of the i-th stand, 8 and 8 are backup rolls, 9 and 10 are a roll gap control device and a load cell, respectively, and 11 and 12 are a roll speed control device including a roll drive motor and a tension detector, respectively.

A tension detector (backward tension detector) 6 detects the tension (backward tension) T _i-1 of the rolled material S behind the i-th stand and outputs this as a signal. A tension detector (front tension detector) 12 detects the tension (front tension) T _i of the rolled material S ahead of the i-th stand and outputs this as a signal. The load cell 10 detects and outputs the rolling load P _i of the i-th stand.

20 is an input device, which includes a rear tension detector 6;
The output of the front tension detector 12 is read at a certain sampling time interval t, converted into a signal suitable for calculation, and input to the calculation processing device 40. 30 is an input device which inputs the output of the load cell 10 at the above-mentioned time interval t.
The signal is read in, converted into a signal suitable for calculation, and input to the calculation processing unit 40.

The arithmetic processing unit 40 calculates the front tension T _i and the rear tension
Based on T _i-1 and rolling load P _i , the equivalent rolling external force F _i that the rolled material S passing through the i-th stand receives every time t, F _i = P _i + P _ti …(1) However, P _ti = Load conversion value of tension = α _i-1・T _i-1 + α _i・T _i …(2) α _i-1 , α _i : Calculate the load conversion coefficient. Regarding the load conversion value of this tension,
It can be determined using known rolling theory. For example, the influence of tension on rolling load is calculated using Karuman's formula (``Theory and Practice of Sheet Rolling'', edited by the Iron and Steel Institute of Japan, published September 1, 1980, p. 17), which is often used in cold rolling. do.

Karuman's formula is shown below.

d(hq)/dx=2p・(+μ+tanφ) However, h: Plate thickness q: Horizontal stress x: Coordinate in rolling direction p: Vertical stress μ: Friction coefficient φ: As shown in Figure 4, this Karuman Analysis using formulas uses fixed rolling conditions such as plate thickness, rolling reduction, deformation resistance, friction coefficient, roll diameter, longitudinal tension, etc. as initial conditions, initial rolling load, advance rate (neutral point position), etc. The following assumptions are given, and the rolling load and advancement rate are determined by repeatedly performing convergence calculations so that the horizontal forces on the rolled material are balanced.

To calculate the load conversion coefficient α _i , change the front tension value T _i by ΔT _i , use the above convergence calculation to find the rolling loads P _i and ΔP _i in each case, and calculate the ratio of the rate of change as the load conversion coefficient. Let α _i . The same applies to rear tension. For example, when the base plate thickness is 2.5 mm and the third stand (i = 3), the plate thickness is 0.923 mm from 1.278 mm.
When rolling from mm to 27.8%, for example, α _i = 10.3, α _i-1 = 15.8.

Next, the standard equivalent rolling external force F _i0 and the equivalent rolling external force
Calculate the deviation from F _i , that is, the rolling external force fluctuation ΔF _i ΔF _i = F _i0 − F _i (3), and if the rolling external force fluctuation ΔF _i exceeds a predetermined range K, the rolling external force fluctuation ΔF _i Of these, the tension portion to be compensated by the tension control system is ΔP _ti , ΔP _ti = β・(ΔF _i /F _i )・P _ti (4) β=control gain is calculated and sent to the rear tension command calculator 50 .
The rear tension command calculator 50 calculates and presets the rear tension share ΔT _i-1 from the tension share ΔP _ti , ΔT _i-1 = (T _i /T _ti )·ΔP _ti (5). The rear tension controller 6 uses the deviation from the tension command value T' _i-1 (T' _i-1 −ΔT _i-1 )...(6) as the new rear tension command value.
Enter 0.

Based on this new rear tension command value, the rear tension controller 60 sets the roll speed command value N _i of the i-th stand and the roll speed command value of the i-1 stand.
N _i-1 and the roll gap command value G' _i of the i-th stand are calculated and input to the corresponding control device.

As is generally well known, if the rear tension change amount of the i-th stand is ΔT _i-1 , ΔT _i-1 = A _i・ΔN _i +B _i・ΔN _i-1 +C _i・ΔG _{i -1} However, A _i , B _i , C _i : Influence coefficient ΔN _i : Amount of change in i-stand roll speed ΔN _i-1 : Amount of change in i-1 stand roll speed ΔG _i : Amount of change in roll gap of i-stand A relationship is established. From this, it is understood that tension control is possible in this example.

In this configuration, now the rear tension command calculator 5
It is assumed that tension command values T' _i-1 and T' _i are set in the forward tension command calculator 0 and a front tension command calculator (not shown), respectively. While the rolled material S is being rolled with the rolling load P _i , the equivalent rolling external force F _i is constant and equal to the standard equivalent rolling external force F _i0 , so the equivalent rolling external force variation ΔF _i =
0, the tension of the rolled material S is maintained at the above tension command value. The skid mark part of the rolled material S is caught between the work rolls 7, 7 and the rolling load is applied.
As described above, when P _i changes to P _ir , the equivalent rolling external force F _i changes to F _ir as shown in FIG.

F _ir = P _ir + P _i …(7) ΔF _i = P _i −P _ir …(8) Therefore, the equivalent rolling external force variation ΔF _i becomes a finite value, and the tension distribution ΔP _ti and rear tension distribution ΔT _i-1
is calculated as shown in the above equations (4) and (5), and the rear tension command calculator 50 gives the tension command value shown in equation (6) to the rear tension controller 50.

As a result, the roll speed control device 11 of the i-th stand performs feedback control on the rotational speed of the work roll drive motor so as to eliminate the deviation between the new roll speed command value N' _i and the speed feedback amount N _fi . i-1 stand roll speed control device 5
The same applies to the roll gap control device 9.

As a result, the equivalent tension load between stand i and stand i-1 of rolled material S is reduced by ΔP _ti , so the rolling load applied to rolled material S is P _ir + ΔP _ti (9), increases compared to traditional methods.

Therefore, the rolling load that has suddenly decreased as shown in FIG. 2b is immediately restored as shown in FIG. 3b, and squeezing into the rolls is prevented.

When the skid mark part passes through the i-th stand and the rolling load recovers to P _i , the equivalent rolling external force variation ΔF _i = 0, so the rear and front tension command values become T' _i-1 and T' _i , respectively. return.

〔Effect of the invention〕

As explained above, the present invention converts the external force that the rolled material receives into a load, calculates the sum as the equivalent rolling external force, and when this fluctuates with respect to a preset reference equivalent rolling external force, a portion of the variation is calculated. By having the tension control system compensate for this, if the rolling load suddenly decreases, the tension applied to the rolled material can be automatically weakened and the rolling load can be restored, preventing rolls from biting into skid marks. Even in such cases, accidents such as roll squeezing can be prevented, and the rolling operation of the rolling mill can be made more stable than in the past.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of external forces applied to the rolled material,
FIG. 4 is a diagram for explaining a method of converting tension into load in the above embodiment. 3, 9... Roll gap control device, 5, 11... Roll speed control device, 6, 12... Tension detector, 7... Work roll, 8... Backup roll, 10... Load cell, 20, 30... Input device, 40... Arithmetic processing device, 50... Rear tension command calculator, 60... Rear tension controller.

Claims (1)

[Claims] 1. In a cold tandem steel plate rolling line using multiple rolling mills, the sum of the rolling load applied to the rolled material and the conversion value of tension to rolling load is calculated as the equivalent rolling external force, and the equivalent rolling external force is the standard equivalent rolling force. A method for controlling the tension of a rolled material, comprising: calculating an equivalent rolling external force variation when the external force fluctuates, and controlling the tension of the rolled material between stands in response to the equivalent rolling external force variation.