DE2143066B2 - Device for regulating the force transmitted in the strip cross-section in a tandem strip rolling mill - Google Patents

Description

The invention relates to a device for regulating the force transmitted in the strip cross section between two successive rolling stands of a Tandeni strip rolling mill according to the generic term of claim 1.

In the case of large tandem mills for cold rolling, the development has recently been going on, larger and larger to use longer tapes and to weld the tapes fed to the rollers beforehand, so that the Tapes are fed endlessly. In these conditions it has become necessary to do a quick one Control of the tension of the strip between the rolling stands of such a tandem train for cold rolling perform, so that products of various shapes are made in an endless rolling process can be.

In such a known device (US-PS 07 i 34), the setpoint value of the control device is fixed specified, which means that it is not possible, in the continuous rolling of steel strip, in particular, if the end of a band with the beginning of a band that is different in width and height to the continuous rollers welded, the same tension in the following band as in the previous one Adjust band.

It is therefore the object of the present invention to develop a device of the type mentioned at the beginning so that that when rolling two strips welded together in the following strip the same cross-sectional tension as maintained in the previous volume.

This *: task is identified by the Features of claim 1 solved

With the invention a device for controlling the tension in a rolling train is provided, wherein the measured change in tape thickness during the size change through the tape thickness before the size change is divided, d. H. - = ■ -, and the measured

The change in width during the size change is divided by the width of the width before the change in size,

i.e.

I iv

the sum of these two values becomes the value

One added, d. H.

Ift

Iw

and the value so obtained is multiplied by the value of the tape tension before the size change, i.e. H.

I / ι
⁺ H ⁺

VV )

The value obtained in this way is ultimately used as the setpoint of the Belt tension entered into the belt tension controller.

The force 7 "(belt tension) transmitted in the belt cross-section is obtained by multiplying the tensile stress f by the belt thickness h and the belt width

T = / χ h

If the change in force is denoted by AT and the change in strip thickness and width is denoted by Ah and Aw Ίο, the following equations are obtained:

7+ IT =

I +

I / i

"Y

IV )

Here, in equations (2) and (3), the

element

l / i I iv

not taken into account as this wen is negligible is small.

The force transmitted in the belt cross-section before the change in dimensions is denoted by V » and the desired value of this force after the change

the dimensions with Ti, then results from the equation (3):

The device according to the invention is used to regulate the belt tension during the change the dimensions of the tape thickness and tape width in the transition section between the front and rear end of the tape created. By this scheme, the tensile stress during the passage of this short section of the connected tape kept constant because there is a risk that the tape breaks due to the changes in thickness and width. Such a break in the ligament not only hampers the Carrying out the endless rolling, but also causes cracks in the surface of the rolls, so that a Replacement of the rollers is required and production must be interrupted. Through the By regulating the tension in the belt, these operating faults are prevented.

An embodiment of the invention is shown in the drawing and will be described in more detail below described.

The drawing shows a circuit diagram of the control device.

In the drawing, a tandem mill is represented by nehreren roll stands, wherein the tensile stress in the rolling stock between the (YJ-th frame and the (/ + l) th frame is maintained at a desired value. There are a (i) -ies stand 1 , a (ι + i) -th stand 2, load cells 3 and 4 for each roll stand, adjusting devices 5 and 6 for each rolling stand, electric motors 7 and 8 for adjusting each rolling stand, electric motors 9 and 10 for driving each rolling stand, a width measuring device 11 , a strip tension measuring device 12, input contacts 13, 14 and 15 in the form of electrical relays which are open during the control process, a circuit 16 for dividing the output signal of the load cell by the spring constant of the roll stand, a circuit 17 for dividing the change in strip thickness by the strip thickness reference value, Memory 18, 19 and 20, a computing element 21, a multiplier 22 and a controller 23 are provided.

With such a device, the tape tension should only be regulated in the event that the Connection between two bands welded together, the bands have a different cross-section.

This happens because certain values are saved shortly before the input contacts open are that certain ratio values are formed when the contacts are open, and rla3 a dem Target value of the belt tension corresponding to Who! is calculated when the contact is open.

Since the device is only used to regulate the tension of the tape at welds of tapes with different Cross-section is used, the opening of the contacts takes place shortly before the occurrence of such Welding point in the first of two roll stands. As long as there is no weld between the roll stands is located, the thickness and width of a band; ils konsiani can be viewed. Accordingly is a It is not necessary to open the contacts until the first connection point enters the first roll stand.

Usually, the rolling is carried out at a speed of 1000 m / min or more, wherein during the control processi; the speed is reduced to about 150 m / min. The contacts are opened when the The person operating the roll stand discovered the welding point. This can be done either by contacting your company Roll stand arranged length measuring device are displayed or simultaneously with reducing the Speed from 1000 m / min to 150 m / min happen. It is also possible to open the

ic contacts with a servo motor or the like by hand or due to an automatic setting perform, whereupon the control process runs.

In detail, the apparatus operates as follows The detected by the load cell 3 rolling force signal P is divided in the circuit 16 by the spring constant of the mill stand M and added to the memory 18 to be supplied to roll position signal S. In the memory 18, the value is stored which is present immediately before the opening of the input contact 13 at the input of the memory. When the input contact 13 at the input of the memory 18 is opened, the immediately preceding value of 5 + P / M and the following (S + P / M} values are compared.

> -i chen and the differences Ah between them fed to the circuit 17. The signal A h / h is obtained at the output of the circuit 17. 1 / Af and Mh correspond to the amplification ratio when the circuits are viewed as amplifiers. M and the tape thickness h

to must be entered manually at the beginning.

The bandwidth signal detected by the width measuring device 11 is sent to the memory 19 and the Computing element 21 is supplied. The L initial value is stored in the memory, which was immediately before the

r> opening of the input contact 14 at the input of the memory 19 is present. The arithmetic unit 21 is designed so that the function 1 - ^ of the two

Input signals w \ and w _{2 is} calculated. That

4 (i output signal of the arithmetic logic unit 21 is equal to zero when the input contact is closed and is 1 - - '? Or ^H when the input contact is open

W ₁ »'

is. wi corresponds to the value of the bandwidth immediately before the opening of the input contact 14 and w ₂ denotes the value of the bandwidth currently detected during the control process. The signal detected by the tape tension knife 12 is fed to the memory 20. The input value w, which is present at its input immediately before the input contact 15 is opened, is stored in the memory 20. The output signal of the memory 20 and the output signal of the sound circuit 17 and the arithmetic logic unit 21 are multiplied by means of the multiplier 22, v, whereby an output signal of the form

/ ο

/ I / i lu \
I, + I

wi receives. If 7o is added to this output signal, you get:

Vi,

lh

The value obtained corresponds to the target value of the band / ugs during the control process Difference / between the setpoint and the actual value

of the strip tension is entered into the controller 23 as a control deviation and the control signal from the controller is passed on to the drive motor for the (i) -le roll stand or the electric motor for the adjustment mechanism of the (/ + 1) -th stand.

If the dimensions of the tape thickness and / or width or the outlet thickness of the tape during the Rolling are changed, the tension of the belt by means of the device can even during the Be kept constant during the transition period. This prevents the tape from tearing and makes it more suitable Guaranteed workflow when changing dimensions.

1 sheet of drawings

Claims (1)

Claim: Device for regulating the transmitted in Bantlquerschnitt force (tape tension) between two ϊ successive roll stands of a tandem strip mill, wherein the actual value of the strip tension detected by a strip tensiometer and is compared with a setpoint value, and wherein either the nip of the next roll stand or w rolling speed of the preceding roll stand is adjusted depending on the result of the comparison in such a way that the actual value is adjusted to the nominal value, characterized in that, for calculating the nominal value, first memory (18, 19) for storing one of the measured values of the adjustment (S) and the rolling force (P) taking into account the spring constant of the roll stand (M) derived strip thickness value (S + P / M) and a measured strip width value (w) as well as a second memory (20) for storing a measured strip tension value (7 " ₀ ) are provided, in each case placed just before opening in front of the first and second store r> pending values can be saved to the input contacts (13,14,15),
that a circuit (17) for calculating the change in the strip thickness value (Ah) based on a predetermined strip thickness (h) and a computing element (21) for calculating the change in the strip width value (A w) based on the strip width (w ) is provided, whereby the values stored in the first memories (18, 19) and the values measured when the contacts (13, 14) are open can be fed to the circuit (17) and the arithmetic element (21), that a multiplier (22) which multiplies the sum of the outputs of the circuit (17) and the arithmetic device (21) with the output signal of the w second memory (20) at more open contact (15), is provided, and that an addition point for adding the output signal of the multiplier (22) with the Output signal of the second memory (20) at i "> open contact (15) is provided.