EP0968780A1 - Method for drawing a continuous casted strand - Google Patents

Abstract

A strand pulling-off method for a metal strand, particularly a steel strip, cast in a curved continuous casting plant, wherein the metal strand is initially vertically pulled from a casting mold, wherein a curved shape is then imparted on the metal strand in a curved entry driver driven with an entry torque, and wherein, after reaching a horizontal strand travel direction, the metal strand is finally straightened in a curved exit driver driven with an exit torque. An entry speed is assigned to the curved entry driver and an exit speed is assigned to the curved exit driver, the entry torque and the exit torque are determined, and the exit speed is adjusted in such a way that the entry torque as well as the exit torque have a positive value.

Description

The present invention relates to a strand withdrawal method for one in one Continuous casting machine, cast metal strand, in particular a steel strip, the metal strand is first drawn vertically from a casting mold, the metal strand is then driven with an input torque Arch input driver is stamped into an arch shape and the metal strand finally after reaching a horizontal strand running direction in one with one Output torque driven sheet output driver straightened becomes.

Such strand withdrawal processes are generally known. With them, the cast Metal strand by means of a driven sheet input driver, too Bending driver called, bent from the vertical into an arc shape. To The metal strand is then reached by means of a driven one Sheet output driver, also called directional driver, bent straight again, so that he the continuous caster in a horizontal direction leaves.

In the best case, the strand runs between the sheet input and sheet output drivers largely circular. Even slight differences in speed between the drivers, however, lead to the fact that the Metal strand is deflected from its ideal line. The metal strand then runs either tendon-shaped or sagging. The speed differences can therefore lead to malfunctions up to an interruption of the Run the foundry. Furthermore, in any case, the quality of the cast metal strand negatively influenced.

Stranggießen von Stahl - Einführung und Grundlagen" von Hans Schrewe, Verlag Stahleisen mbH, Düsseldorf 1987, Seiten 13 und 46 bis 50 ist ein Strangabzugsverfahren für einen in einer Bogenstranggießanlage gegossenen Metallstrang, insbesondere ein Stahlband, bekannt, wobei der Metallstrang zunächst aus einer Gießkokille senkrecht abgezogen wird, dem Metallstrang sodann in einem Bogeneingangstreiber eine Bogenform aufgeprägt wird, der Metallstrang sodann in einem Vielrollenantrieb geführt wird und der Metallstrang in mehreren Schriften gerade gerichtet wird, so daß er nach Erreichen einer waagrechten Stranglaufrichtung aus der Bogenstranggießanlage ausläuft. From the specialist book

Continuous Casting of Steel - Introduction and Fundamentals "by Hans Schrewe, Verlag Stahleisen mbH, Düsseldorf 1987, pages 13 and 46 to 50 discloses a continuous withdrawal method for a metal strand cast in an arc continuous casting installation, in particular a steel strip, the metal strand initially being vertical from a casting mold is withdrawn, the sheet of metal is then stamped into an arc shape in a sheet entry driver, the sheet of metal is then guided in a multi-roller drive and the sheet of metal is straightened in several writings, so that it runs out of the sheet-continuous casting machine after reaching a horizontal strand direction.

The object of the present invention is a strand withdrawal method to provide, by means of which a deviation of the cast metal strand from its ideal line is avoided as far as possible.

The object is achieved in that the sheet input driver has an input and an output speed is predefined for the sheet exit driver, that the input and output torque are detected and that the Output speed is set so that both the input and the output torque also has a positive value.

The output speed is preferably reduced when the quotient from the output torque to the input torque exceeds a quotient setpoint, and vice versa the output speed increases when the quotient of output torque for the input torque falls below the quotient setpoint. Because this keeps the ideal line even better.

The quotient setpoint is preferably increased if after a decrease the output speed is the sum of the output torque and the input torque increases and conversely the quotient setpoint decreases if after a Increase the output speed the sum of output torque and The input torque increases. Because this ensures that the continuous sheet caster automatically an optimal strand course. At the same time, it uses minimal energy operated.

Figur 1

ein Blockschaltbild einer Bogenstranggießanlage und

Figur 2

ein Flußdiagramm zur Steuerung der Bogenstranggießanlage.

Further advantages and details emerge from the following description of an exemplary embodiment. Show in principle

Figure 1

a block diagram of a sheet caster and

Figure 2

a flow chart for controlling the continuous sheet caster.

According to FIG. 1, a continuous sheet caster has a casting mold 1, one below it arranged heat sink 2, a sheet input driver 3 and a sheet output driver 4 on. In the casting mold 1, liquid metal, e.g. Steel, too a metal strand 5, e.g. a supporting act, cast. The metal initially solidifies on the outside and with the core still liquid, it becomes vertical from the casting mold 1 subtracted. When passing through the heat sink 2, the metal strand 5 cooled so far that it solidified in its core.

After solidification, the metal strand 5 passes through the sheet input driver 3. The sheet input driver 3 has driven input rollers 6. The input rollers 6 are driven with an input torque F _e . The metal strand 5 is withdrawn from the casting mold 1 at a casting speed v _G by means of the input rollers 6. Furthermore, an arc shape is impressed on the metal strand 5 by means of a bending roller 6 ', ie it is bent off from the vertical.

After passing through the sheet entry driver 3, the metal strand 5 runs freely up to the sheet exit driver 4. After the metal strand 5 has entered the sheet exit driver 4, the metal strand 5 reaches a horizontal strand running direction x. The sheet exit driver 4 has driven exit rollers 7. The output rollers 7 are driven with an output torque F _a . The metal strand 5 is conveyed further by means of the output rollers 7. Furthermore, the metal strand 5 is straightened again by means of the exit rollers 6, ie it is bent back from the arch shape into the horizontal.

The drives for the sheet input driver 3 and the sheet output driver 4 can be of any type. Electric motors are mostly used. In the case of electric motors in particular, the moments F _e , F _a can be easily detected.

The sheet input driver 3 and the sheet output driver 4 are speed-controlled. You are therefore given an input and an output speed v _e , v _a . The input speed v _e is predetermined by the casting speed v _G. The output speed v _a, however, is available as a control parameter. Instead of the speeds v _e , v _a , the speeds of the rollers 6, 7 can of course also be regulated.

In order to regulate the output speed v _a , the input and output torque F _e , F _a are recorded according to FIG. If the input torque F _{e has} a negative value, the output speed v _{a is} reduced, since the metal strand 5 is then conveyed too quickly by the sheet output driver 4. Conversely, if the output torque F _{a has} a negative value, the output speed v _{a is} increased since the metal strand 5 is then conveyed too slowly by the sheet output driver 4. If both the input and the output torque F _e, F _{a have} a positive value, the delivery rate is distributed to both drivers 3, 4, which corresponds to the desired state. As a result, the output speed v _{a is set} such that both the input and the output torque F _e , F _{a have} a positive value.

In order to ensure that the delivery capacity is distributed as evenly as possible among both drivers 3, 4, a quotient setpoint n is defined. If the quotient from output torque F _a to input torque F _e exceeds the quotient setpoint n, the output speed v _{a is} reduced. Conversely, if the quotient from output torque F _a to input torque F _e falls below the quotient setpoint n, the output speed v _{a is} increased. The quotient setpoint n preferably has a value above one.

According to FIG. 2, increasing or decreasing the initial speed v _a is an iterative process. In each iteration, the sum S of the output torque F _a and the input torque F _{e is} formed and compared with the sum S 'of the output torque F _a ' and the input torque F _e 'of the previous iteration. If the sum S of output torque F _a and input torque F _{e of} the current iteration does not exceed the sum S 'of output torque F _a ' and input torque F _e 'of the previous iteration, the quotient setpoint n remains unchanged. If, on the other hand, the sum S of the output torque F _a and the input torque F _{e of} the current iteration exceeds the sum S 'of the output torque F _a ' and the input torque F _e 'of the previous iteration, this is an indication that the continuous sheet caster is not yet being optimally operated. In this case, the quotient setpoint n is increased if the initial speed v _a was previously reduced. Conversely, the quotient setpoint n is reduced if the output speed v _{a has} previously been increased.

By means of the strand withdrawal method according to the invention, an optimal operation of the continuous strand casting installation is automatically set independently of other parameters such as the strand temperature, the strand width and thickness, the casting speed v _G , the change in the roll diameter due to wear and the cast metal type and quality. This is particularly important for thin slab casting plants with which slabs with a thickness between 40 mm and 100 mm are cast. Because with thin slab casting plants the casting speed v _{G is} considerably higher than with conventional slab plants, so that critical plant states can be reached quickly without corrective regulation. In addition, the tendency to vibrate the metal strand 5 is suppressed or damped and the metal strand 5 is prevented from slipping by the strand withdrawal method according to the invention. The geometry of the metal strand 5 is also improved. Finally, the tendency of the metal strand 5 to run obliquely is reduced, which among other things leads to improved run-in behavior in the downstream units in the continuous sheet casting installation.

Reference list

1

Casting mold

2nd

Heatsink

3rd

Sheet input driver

4th

Sheet output driver

5

Metal strand

6

Entry roles

6 '

Bending roll

7

Initial roles

F _a , F _a ',

F _e , F _e '

Moments

n

Quotient setpoint

S, S '

to hum

v _a , v _e ,

v _G

Speeds

x

Strand running direction

Claims (3)

Extraction process for a metal strand (5) cast in an arc continuous casting installation, in particular a steel strip (5),
the metal strand (5) first being drawn off vertically from a casting mold (1),
wherein the metal strand (5) is then imprinted in a sheet input driver (3) driven with an input torque (F _e ) and
the metal strand (5) finally being straightened after reaching a horizontal strand running direction (x) in a sheet output driver (4) driven with an output torque (F _a ),
wherein the sheet input driver (3) is given an input (v _e ) and the sheet output driver (4) an output speed (v _a ),
the output torque (F _a ) is detected,
characterized,
that the input torque (F _e ) is also detected and that the output speed (v _a ) is set such that both the input (F _e ) and the output torque (F _a ) have a positive value. Strand withdrawal method according to claim 1,
characterized,
that the output speed (v _a ) is reduced when the quotient from output torque (F _a ) to input torque (F _e ) exceeds a quotient setpoint (n), and
that, conversely, the output speed (v _a ) is increased when the quotient from output torque (F _a ) to input torque (F _e ) falls below the quotient setpoint (n). Strand withdrawal method according to claim 2,
characterized,
that the quotient setpoint (n) is increased if, after the output speed (v _a ) has decreased _, the sum (S) of the output torque (F _a ) and the input torque (F _e ) increases and
conversely, that the quotient setpoint (n) is reduced if, after an increase in the output speed (v _a ), the sum (S) of the output torque (F _a ) and the input torque (F _e ) increases.

Images