JPS5820683B2 - Renzokushikiatsuenkiniokeruchiyouriyokuseigiyohouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the tension of a rolled material in a continuous rolling mill.

Generally, when rolling strips, especially steel bars, wire rods, etc., with a continuous rolling mill, products with constant dimensions are manufactured by performing so-called tension control, which keeps the tension acting between each rolling mill constant or zero. .

For this tension control, there is a current memory system that keeps the drive motor current of each rolling mill at a constant value.
There is a rolling car torque method known from Japanese Patent Publication No. 49-37909, etc., and both methods detect changes in the tension acting on the strip as changes in the current or torque of the drive motor.

However, these conventional methods have various drawbacks and cannot provide good control.

In other words, as disclosed in Japanese Patent Publication No. 48-37904, for current memory and torque memory single-type systems, changes in current and torque values are simply caused by changes in tension, so thermal rundown, etc. This method could not be applied at all to cases where the rolling load changes due to changes in the rolled material itself.

Also, Special Publication No. 48-37904 and Special Publication No. 49-37
The rolling torque method proposed by No. 909 etc. assumes that rolling torque and rolling force are proportional;
From the rolling torque Go and the rolling force Pe before the strip bites into the first stand and bites into the i-th +1 stand, the proportionality constant (so-called torque arm) K of both is calculated as = Go/Po, and the memory is stored. After the i-th + 1st stand is engaged, the difference between the momentary rolling torque G and the target rolling torque G', which is obtained from the memorized torque arm and momentary rolling force P, that is, the amount ΔG expressed by the following, becomes the i-th , i+1 stand, and the speed of the i-th or i+1-th stand is controlled so that this ΔG becomes a constant value or zero.

However, when the relationship between rolling torque G and rolling force P is determined from actual rolling data, it is as shown in Figure 1. There is no proportional relationship between them, and when approximating with a straight line, there is a slope that does not pass through the origin. It is confirmed that it is a steep linear equation.

Therefore, as in the conventional method, the rolling torque G before the i + 1st stand engages.

and rolling force P. If we calculate the torque arm K as = Go/Po, in Fig. 1, the rolling force is 50 TO
When the torque changes to H, the actual tensionless rolling torque B is judged to be torque A, resulting in an error corresponding to AB, and according to the illustrated example, this amounts to as much as 20 times the total torque.

Therefore, Special Publication No. 48-37904 and Special Publication No. 49-3
Although the system of No. 7909 is improved over the single current memory system, the above-mentioned errors are large, and in the case of multiple stands, such errors accumulate, making it impossible to perform good tension control.

The present invention has been made in view of these drawbacks of the driven method, and its purpose is to provide a stable and good tension control method.

In other words, the conventional method described above uses absolute values of rolling torque, rolling force, etc., which results in large errors, and because it attempts to obtain the torque arm K online during rolling, it does not suit the actual situation.
However, the present invention departs from such a hypothetical method in the conventional method and instead of determining the torque arm online, it uses actual rolling data in advance. The relationship between rolling torque and rolling force as shown in Figure 1 obtained by analysis is expressed as the rate of change ΔG
The rolling torque G of the i stand before biting into the i+1th stand is calculated using the type ΔP in the range of rolling force that can be assumed, and stored for each rolling size and stand.

, rolling force P. and the i+1st stun. The tension torque is the error obtained from the calculation of the rolling torque G and the rolling force P at every moment of the i-stand after it has been bitten into the cylinder.

It is.

That is, compared to the torque memory one-type control so that G=Go, the change in rolling force P-P.

, the rolling force P of the rolling stand i of the rolling size.

Multiply by the rate of change in the vicinity (△G/△P)! The memory torque value is corrected by the combined amount, and the torque target value is calculated as the difference △G from the rolling torque G actually obtained from the detector.
The speed of the i-th or i+1-th stand is adjusted accordingly.

Here, the relationship between rolling torque and rolling force is memorized in the form of a rate of change, because if the rolling chances are different, the torque
This is because although the absolute value of the rolling force fluctuates, the rate of change does not fluctuate much. In this way, the present invention uses relative values to suppress errors.

More G.

Since a torque arm including an error such as /Po is not used, there is no error associated with calculation of the torque arm.

Here, the rate of change ΔG/ΔP may be a constant within a predetermined rolling force range in the case shown in FIG. 1, but generally the relationship between rolling torque and rolling force is non-linear.

However, since the extent of this is small, it is better to divide the rolling force range into three or four sections, store the rate of change ΔG/ΔP, and use an interpolation method.

Next, the method of the present invention will be explained using examples.

FIG. 2 shows how the method of the present invention can be applied to any consecutive
This is an example applied to one stand, and each rolling mill has a motor M (in the figure, Mi indicates the motor of the i stand, and Mi+1 indicates the motor of the i stand).

The motor M is controlled by a speed control device A, and the motor M is equipped with a speed transmitter V.
are linked.

L is a rolling force detector, and in the case of the figure, a load cell is used.

C is a computing device and a memory device, and S is a setting device for setting the rolling size.

R represents a rolling roll. When it is detected by the output of the rolling force detector Li that the strip T is caught in the i-th stand, the calculator 0 receives the rolling force P from the detector Li, the rolling power E from the speed control device Ai, and the speed. Rather than acquiring each signal from the transmitter Vi, it starts scanning at a constant cycle.

Next, when it is detected by the output of the rolling force detector L i + 1 that the strip is caught in the i+i-th stand, each scan value (rolling force P) of the minus cycle before is detected.

, rolling power Fo, motor speed V.

), save the rolling power formula of the motor and the motor speed V.

Calculate the rolling torque Go from which ratio.

At this time, it is a matter of course that the acceleration torque, slip torque, etc. are corrected (9).

Next, rolling force P.

and the rolling size set by the external setter S and the rolling force P at the rolling size at the i-th stand.

The computing unit C looks up the nearby change rate (ΔG/ΔP) from the memory.

In this way, after the i+1 stand is engaged, the rolling torque G and the rolling force P are scanned every control cycle, and the target torque σ is set to the memory value G before the i+1 stand engages.

Assuming that a correction is made for the change in rolling force, the error torque △G=
In order to correct the speed of the i-th or i-th stand according to the G-ge, the speed control device Ai or A i +
1, an output is output from the arithmetic unit C.

Here, the storage unit C1 may be stored in a computer, and the setting unit S for setting the rolling size may also be a higher-level computer.

As described above, according to the present invention, since rolling data obtained from actual rolling is used instead of using inaccurate assumptions, errors caused by mathematical formulas and models are small, and rolling data can be improved without using absolute value calculations. This is stored in the form of the rate of change in torque relative to rolling force, and this is multiplied by the variation in rolling force to focus on only the variation, so there are fewer errors associated with calculations, and stable and good tension control can be performed. .

[Brief explanation of the drawing]

Figure 1 is a chart showing the relationship between rolling torque and rolling force, Figure 2 is a chart showing the relationship between rolling torque and rolling force.
The figure is a configuration diagram showing an embodiment of the present invention. R...roll stand, M: electric motor, ■=speed transmitter, L...rolling force detector, A...speed control device, S.
... Setting device, C: Arithmetic device, D... Memory device, T: Strip material.

Claims (1)

[Claims] 1. In a tension control device for a continuous rolling mill that maintains the rolling torque of each stand constant during rolling, the rate of change of rolling torque with respect to rolling force for each rolling size and stand is controlled at a predetermined value. The rolling force range is stored in advance, and the torque target value is corrected by the product of the amount of change in the rolling force of the stand during rolling and the rate of change. A method for controlling tension in a continuous rolling mill, characterized by controlling tension in a continuous rolling mill.