DE2143066C3 - Device for regulating the force 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 tandem 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 one endless rolling process can be.

In such a known device (US-PS 07 134), the setpoint 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 object is achieved by the characterizing features of the claim.

With the invention a device for controlling the tension in a rolling train is provided, wherein the measured change in strip thickness during the change in size due to the strip 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,

d. H. - ". The sum of these two values becomes the value One added, d. H.

I / i

/1

In the·

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

The value obtained in this way is then entered as the nominal value of the belt tension into the belt tension controller.

The force T transmitted in the belt cross-section (belt tension) is obtained by multiplying the tensile stress t by the belt thickness Λ and the belt width

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

I 7 '= 7

V hw

V hw J

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

Element !''.'"
hw

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

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

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

τ, =

With egg device according to the invention a Control of the belt tension while changing the dimensions of the belt thickness and belt width created in the transition section between the front and rear end of the tape. Through this scheme the tension becomes constant during the passage of this short section of bonded tape held because there is a risk that the tape breaks due to the changes in thickness and width. Such breakage of the strip not only hinders the continuous rolling from being carried out, but also causes it Cracks in the surface of the rollers, so that the rollers must be replaced and the Production must be interrupted 3. By regulating the tension of the belt, these malfunctions are avoided 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 shown having a plurality of roll stands, wherein the tensile stress in the rolling stock fell between the stand and the (+ l) th frame is maintained at a desired value. There are a (i) -ies stand 1, a (/ + l) -th stand 2, load cells 3 and 4 for each roll stand, adjusting devices 5 and 6 for each roll stand. Electric motors 7 and 8 for the employment of each roll stand, electric motors 9 and 10 to drive each roll 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 strip thickness change by the strip thickness reference value, memories 18, 19 and 20, a calculator 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 of two bands welded to one another, the bands have a different cross-section.

This happens because certain values are saved shortly before the input contacts open that certain ratio values are formed when the contacts are open, and that a dem The desired value of the strip tension corresponding to the value when the contact is open is calculated.

Since the device is only used to regulate the tension of the tape at welds of tapes with different Cross-section is used, aas opening of the contacts takes place shortly before the occurrence of such Welding point in the first two roll stands. As long as there is no welding point between the roll stands, the thickness and width of a strip can be considered constant. Accordingly, it is not necessary to open the contacts until the first connection point in the first roll stand.

Normally, the rolling is carried out at a speed of 1000 m / min or more, with during the control process the speed is reduced to about 150 m / min. Opening the Contacts is made when the person operating the roll stand has reached the weld ι discovered. This can be done either by sending an to your 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

in contact with a servo motor or similar from Manually or based on an automatic setting, whereupon the control process expires.

In detail, the device works as follows. That

ι ", the rolling force signal P detected by the load cell 3 is divided in the circuit 16 by the spring constant of the rolling stand M and added to the roll position signal S to be supplied to the memory 18. The value is stored in the memory 18 which is immediately

Ju is present before opening 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 S + P / M and the following (S + P / M) values are compared.

2Ί chen and the differences Ah between them fed to the circuit 17. The signal Ah / h is obtained at the output of the circuit 17. Ι / Λ / and Mh correspond to the amplification ratio when the circuits are viewed as amplifiers. M and the strip thickness Λ 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 input value is stored in the memory, which immediately before the

j-, opening the input contact 14 at the input of the Memory 19 is present. The arithmetic logic unit 21 is designed so that the function 1 - "i of the two

"1

Input signals w \ and w-2 are calculated wildly. The output signal of the arithmetic unit 21 is equal to zero when the input contact is closed and is equal to

1 -

1 ™

or __ if the input contact is open

is. Wi corresponds to the value of the bandwidth immediately 4> before the opening of the input contact 14 and w ₂ designates 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 ~> o, 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 circuit 17 and the arithmetic logic unit 21 are multiplied by means of the multiplier 22. ■ -, ■■> giving an output of the form

/ IZ ₁ Uv

^{7 (1} VT ⁺ w.

«Ι receives. If To is added to this output signal, you get:

I / i

InA

ν)

The value obtained corresponds to the target value of the belt tension during the control process. Of the 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 (/ '+ l) -th stand.

If the dimensions of the tape thickness and / or width or you run-out 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 force transmitted in the belt cross-section (belt tension) between two successive rolling stands of a tandem strip rolling mill, with the actual value of the strip tension is detected by a tape tension measuring device and compared with a nominal value, and either the Roll gap of the following roll stand or the rolling speed of the preceding roll stand is adjusted depending on the result of the comparison in such a way that the actual value corresponds to the setpoint is adjusted, characterized in that that for calculating the nominal value first memory (18, 19) for storing a from measured values of the pitch (S) and the rolling force (P) taking into account the spring constant of the rolling stand (M) derived strip thickness value (S + P / M) and a measured one Bandwidth value (w) and a second memory (20) for storing a measured band tension value (To) are provided, with the values pending shortly before the opening of the input contacts (13, 14, 15) arranged in front of the first and second memories being storable,
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) are provided, wherein the values stored in the first memories (18, 19) and the measured values when the contacts (13, 14) are open can be fed to the circuit (17) and the computing element (21), that a multiplier (22) which the sum of the output signals of the circuit (17) and the Arithmetic element (21) with the output signal of the second memory (20) when the contact (15) is open multiplied, provided and that an addition point for adding the output signal of the multiplier (22) with the Output signal of the second memory (20) is provided when the contact (15) is open.