EP1519798B1 - Method and casting roller plant for the semi-endless or endless rolling by casting of a metal in particular a steel strip which may be transversely separated as required after solidification - Google Patents

Abstract

A method for semi-endless or endless rolling by casting a metal strand, especially a steel strand, which is cut to length as required after solidification, wherein the cut lengths of cast strand are fed into a roller hearth furnace for heating and homogenizing at rolling temperature and are then fed at rolling temperature into a rolling mill to be rolled out. The continuous casting is continued without interruption during the rolling operation, and a sufficient buffer time for a roll change is maintained in the rolling mill. For carrying out a roll change, the casting rate is reduced as a function of the feed rate of the rolling mill and/or the roll-changing time, and/or the buffer length of the roller hearth furnace, and/or the final rolled thickness after the strand has been cut to length.

Description

The invention relates to a method and a casting rolling mill for semi-endless or continuous rolling by casting a metal, in particular a Stahlfstrangs which is transversely divided if necessary after solidification, the Gießstrang part lengths are guided in a roller hearth furnace for heating and uniform to rolling temperature, and the part-length rolling temperature for rolling in a rolling mill are introduced, wherein the continuous casting is continued during the rolling operation without interruption.

Such a method is known from EP 0 264 459 B1. In this process, the Gießstrang partial lengths are stored in the tunnel furnace under cross-transport.
The Gießstrang part lengths are stored over a period corresponding to a multiple, eg four times, their casting time. Further, the method is practiced such that the rolling of each casting strand part length is carried out in a unit of time, which corresponds to only a fraction, eg one-fifth of its casting time, and to the effect that the rolling carried discontinuous and thereby the rolling process in each case over a tent area , which corresponds to the difference between a casting time and a rolling, is interrupted with a pause time. This method is strictly based on continuous casting and is not adapted to the rolling process.

European patent application EP 0 853 987 A2 discloses a system for producing a strip, a pre-strip or a slab. The disclosed there invention is based on the object to create a system, which enables high-quality production of the thinnest possible bands, with a very high operational flexibility is given. In particular, the continuous casting should be able to continue in the case of a fault at a downstream of the continuous mold deformation stage. To solve this problem, it is proposed to make the various shaping stages downstream of the mold activatable or deactivatable, wherein for the production of a very thin strip all deformation stages should be activated in total, wherein for the production of a strip with a slightly greater thickness, only the second and third deformation stage should be activated individually or in total and to disable all three deformation stages to produce an undeformed slab.

Furthermore, US Pat. No. 5,396,695 discloses a method and a device according to the preambles of claims 1 and 9, respectively, for controlling a period of time between the continuous casting of metal strands and their entry into a rolling stand. The invention disclosed there is based on the finding that it takes longer to cast a thicker slab than a thinner slab of the same length. It can therefore be controlled by adjusting or changing the cross section of the cast strand, the speed at which the cast strand emerges between pinch rollers, at the same casting rate. In particular, it is in this way, i. by increasing the cross-section of the cast strand, it is possible to gain time for a roll change at the same flow rate.

Starting from this prior art, the object of the invention is to provide an alternative method and an alternative device, in which it is also possible to set time, e.g. to win for a roll change within a rolling mill.

This object is achieved according to the method claimed in claim 1, characterized in that between rolling campaigns within a casting sequence after the cross-cutting the final rolling thickness and / or the drawing speed of the rolling mill is increased.

Thereby, the semi-endless rolling and the endless rolling are adjusted to the conditions of rolling, and a buffer time for the inevitable roll change is provided.

The larger rolling stock lengths resulting from the semi- or continuous rolling are taken into account in that several coils are produced from one multiple length.

The buffer time for the roll change can still be influenced by reducing the casting speed as a function of the drawing speed of the rolling train and / or the roll change time, including the calibration time and / or the buffer length of the roller hearth furnace and / or the final rolling thickness after the transverse cutting.

According to another feature, it is proposed that the buffer length of the roller hearth furnace is tuned to at least one roller level.

wobei bedeuten:

ΔV =

Gießgeschwindigkeitsreduzierung

V_w =

Einzugsgeschwindigkeit des Walzwerks

Δt =

Walzenwechselzeit und

L =

Länge des Tunnelofens.

In order to achieve the desired buffering time, it is further advantageous that the casting speed V _c , which corresponds to the drawing speed V _{w of} the rolling mill, is reduced to be equal or greater according to the following formula: $$\mathrm{\Delta }\mathrm{V}={\mathrm{V}}_{\mathrm{W}}-\frac{1}{\mathrm{\Delta }\mathrm{t}/\mathrm{L}+1/{\mathrm{V}}_{\mathrm{W}}}\mathrm{}\left(\mathrm{m}/\min \right).$$

where:

ΔV =

Gießgeschwindigkeitsreduzierung

V _w =

Feed speed of the rolling mill

Δt =

Roll change time and

L =

Length of the tunnel kiln.

An embodiment is further that a combination of an adaptation of the casting speed and the final rolling thickness is used to optimize the production capacity.

It is also advantageous if the Endwalzdicke is increased by a maximum of a factor of 2.5.

Another buffering time can be achieved by maximizing the final rolling thickness by a factor of 2 and lowering the casting speed to a minimum of 30%.

The method can be applied according to a practical example such that after the cross-cutting the casting speed is reduced and / or the feed speed of the rolling train and / or the final roll thickness are increased, after the completion of rolling the worn rolls of the rolling train are changed and after the roll change the Casting speed is increased to the feed speed of the rolling mill.

The above object of the invention is further achieved by the subject-matter claimed in claim 9.

The strand guide can also be designed so that multiple lengths can be inserted at a single height level from the outlet of the continuous casting machine through the roller conveyor of the roller hearth furnace into the rolling mill.

In the drawings, embodiments of the invention are shown, which are explained below procedural and device technology closer.

Fig. 1

die Gießwalzanlage mit einem Rollenherdofen und einer Rollenebene in Seitenansicht,

Fig. 2A

eine Seiten-Teilansicht mit einem Gießstrang, wobei die Gießgeschwindigkeit gleich oder kleiner der Walzgeschwindigkeit ist,

Fig. 2B

dieselbe Ansicht bei auf Walzgeschwindigkeit erhöhter Transportgeschwindigkeit einer Gießstrang-Teillänge,

Fig. 3A

das Endlos-Gießen und -Walzen bei gleicher Gieß- und Walzgeschwindigkeit und mit zwei Haspelanlagen,

Fig. 3B

das Endlos-Gießen und -Walzen mit den zwei Haspelanlagen,

Fig. 4A

die Situation beim Walzenwechsel und reduzierter Gießgeschwindigkeit,

Fig.4B

die Situation nach beendetem Walzenwechsel und gesteigerter Gießgeschwindigkeit und

Fig. 5

die Gießwalzanlage in der Seitenansicht wie Fig. 1 für eine alternative Ausführungsform.

Show it:

Fig. 1

the cast rolling mill with a roller hearth furnace and a roller level in side view,

Fig. 2A

a partial side view with a cast strand, wherein the casting speed is equal to or less than the rolling speed,

Fig. 2B

the same view when the transport speed of a cast strand partial length is increased at rolling speed,

Fig. 3A

Continuous casting and rolling at the same casting and rolling speed and with two coiler units,

Fig. 3B

the endless casting and rolling with the two coiler lines,

Fig. 4A

the situation during roll change and reduced casting speed,

4B

the situation after completion of roll change and increased casting speed and

Fig. 5

the casting rolling mill in the side view as Fig. 1 for an alternative embodiment.

In Figure 1, a casting rolling mill is shown in side view, consisting of a continuous casting machine 1, in which a cast strand 1a is produced, a roller hearth furnace 2 and a rolling mill 3 with the associated ancillary equipment.

In the continuous casting machine 1, a distributor vessel 4 is fed from a ladle (not shown) to which a continuous casting mold 5, a support roll stand 6 with a bending unit 7 and a straightening machine 8 are arranged downstream. At the output 9 is a cross-cutting device 10 and behind this (as an alternative in Fig. 5) a pivotable roller conveyor 11 for the input 12a of the roller hearth furnace 2 is arranged. At its output 12b are again a pivotable roller conveyor 13 and a cross-cutting device 14. The basic embodiment in Fig. 1 operates without the pivotable roller conveyors 11, 13th

The rolling train 3 begins after the cross-cutting device 14 with a descaling device 15. Then follows the rolling mill 3 with about five to seven rolling stands. Behind the rolling stands, a cooling section 17 and this following two coiler 18 are provided after a separator 16.

The method is used for semi-continuous rolling or continuous rolling by casting of liquid metal, in particular of liquid steel, to form a cast strand 1 a, which after solidification in the cross-cutting device 10 in Gießstrang part lengths 20 is transported in the roller hearth furnace 2. The respective Gießstrang part length 20 is heated in the roller hearth furnace 2, evened out in temperature and brought to rolling temperature for rolling in the rolling mill 3. During this time, the continuous casting continues without interruption.

In the event that the rollers 3a are worn, the casting speed V _{c is} lowered for a roll change such that between the end of rolling a previous multiple length 21 and the piercing of a new part length 20 or multiple length 21 in the rolling train 3 sufficient buffer time for the roll change is available. From the multiple length 21 more coils 22 can be wound.

The casting speed V _c , for example, depending on the feed speed
V _{w of} the rolling train 3 and / or the respective roller change time including a calibration time and / or the buffer length 23 of the roller hearth furnace 2 and / or the final rolling thickness reduced after the cutting. The buffer length 23 of the roller hearth furnace 2 can be matched to at least one roller plane 24 (see Fig. 1).

In FIG. 2A, the casting speed V _{c is set} equal to or less than the drawing speed V _w in the rolling mill 3. As shown in FIG. Once the roller hearth furnace 2 is charged, the speed V _c can be raised again to the pull-in speed V _w , as shown in FIG. 2B.

In Fig. 3A, the endless rolling is shown. The casting strand 1a is guided and rolled at a casting speed V _c equal to the drawing speed V _w in the first rolling stand, then cooled, wound and cut in the separating device 16. After a transverse division in the transverse dividing device 10, the cast strand 1a can, as shown in Fig. 3B, with reduced casting speed V _{c are} cast and the separated Gießstrang part length 20 is rolled at the pull speed V _w and wound.

wobei bedeuten:

ΔV =

Gießgeschwindigkeitsreduzierung (m / min)

V_w =

Einzugsgeschwindigkeit des Walzwerks (m / min)

Δt =

Walzenwechselzeit (min)

L =

Länge des Tunnelofens (m).

The casting speed V _c is reduced equal to or greater than the following formula: $$\mathrm{\Delta }\mathrm{V}={\mathrm{V}}_{\mathrm{W}}-\frac{1}{\mathrm{\Delta }\mathrm{t}/\mathrm{L}+1/{\mathrm{V}}_{\mathrm{W}}}\mathrm{}\left(\mathrm{m}/\min \right)$$

where:

ΔV =

Casting speed reduction (m / min)

V _w =

Feed speed of the rolling mill (m / min)

Δt =

Roll change time (min)

L =

Length of tunnel kiln (m).

At a take-in speed V _w = 10 m / min, a roll change time Δt = 10 min and a roller hearth furnace length L = 200 m, the casting speed V _c must be reduced by at least 3.33 m / min. $$\mathrm{Gießgeschwindigkeitsreduzierung}\mathrm{}\mathrm{\Delta }\mathrm{V}=10-\frac{1}{10/200+1/10}=10-\frac{1}{3/20}=10\mathrm{}\mathrm{m}-6.67\mathrm{}\mathrm{m}=3.33\mathrm{}\mathrm{m}/\min$$

The roll change is shown in Fig. 4A. The casting speed V _c is 6.67 m / min according to the above calculation and is accordingly lower than the pull-in speed V _w . After the roll change, Fig. 4B, the casting speed V _{c is increased} again to the pull-in speed V _w .

Between the rolling campaigns within a casting sequence, the final rolling thickness and / or the drawing speed V _{w of} the rolling train 3 can be increased after the transverse cutting.

However, it is also possible to use a combination of an adaptation of the casting speed V _c and the final rolling thickness to optimize the production output. The final rolling thickness can be increased by a maximum of 2.5 times. Another option is to maximize the finish roll thickness by a factor of 2 and lower the casting speed to a minimum of 30%.

In another embodiment, it is provided that after the cross-casting, the casting speed V _{c is} reduced, and / or the drawing speed V _{w of} the rolling mill 3 and / or the final roll thickness are increased, after the completion of rolling the worn rolls 3a of the rolling mill 3 are changed and after the roll change, the casting speed V _{c is increased} to the drawing speed V _{w of} the rolling train 3.

The casting and rolling mill for semi-endless or continuous rolling a cast metal or steel strand, which is divisible as cast strand 1a in the solidified state if necessary in Gießstrang part 20 and the Gießstrang part lengths 20 are kept warm in a roller hearth furnace 2 and heated to rolling temperature and homogenized and subsequently introduced into a rolling mill 3 presupposes that continuous casting takes place on the continuous casting machine 1. For this purpose, between the continuous casting machine 1 and the rolling train 3 of the roller hearth furnace 2 with at least one roller plane 24, at the input 12a and / or output 12b, a cross-dividing device 14, below a descaling device 15 are provided on it first rolling mill follows and behind the rolling mill 3, the separator 16, cooling section 17 and coiler 18 are arranged.

The inlet and outlet side roller conveyors 11, 13 have bending and / or straightening units 7, 8, which can be set or set up on the respective roller plane 24. Thus, the pivotable roller conveyors 11, 13 are provided at the entrance 12a and at the exit 12b of the roller hearth furnace 2 with at least two roller levels 24, each with a bending and / or straightening unit 7, 8 (see Fig. 5).

According to the alternative construction in FIG. 5, multiple lengths 21 on a plurality of roller planes 24 from the outlet 9 of the continuous casting machine 1 through the pivotable roller conveyor 11 of the roller hearth furnace 2 can be performed via the pivotable roller conveyor 13 into the rolling train 3.

LIST OF REFERENCE NUMBERS

1

continuous casting

1a

cast strand

2

Roller hearth furnace

3

rolling train

3a

roller

4

distribution vessel

5

continuous casting

6

Supporting roll framework

7

bending unit

8th

straightener

9

output

10

Transverse separating device

11

roller conveyor

12a

entrance

12b

output

13

swiveling roller conveyor

14

Transverse separating device

15

descaling

16

separator

17

cooling section

18

coiler

19

20

Cast strand length

21

Multiple length

22

coil

23

buffer length

24

role level

Claims (10)

1. A method for the semi-endless or endless rolling by casting of a metal, in particular a steel strip (1a), which is transversely separated as required after solidification, the casting strip partial lengths (20) are fed into a roller hearth furnace (2) for heating and equilibration at rolling temperature, and the partial lengths (20) are introduced at rolling temperature into a roll train (3) for rolling out, wherein the continuous casting is continued without interruption during the rolling operation and wherein between the end of the rolling of a preceding multiple length (21) and the insertion of a new partial length (20) or multiple length (21) in the rolling mill, a sufficient buffer time is maintained for a change of rollers, by reducing the casting speed (V_c) depending on the infeed speed (V_w) of the roll train (3) and/or the roller exchange time including the calibration time and the buffer time (23) of the roller hearth furnace (2) and/or the end roll thickness after transverse separation,
   characterised in
   that the end roll thickness and/or the infeed speed (V_w) of the rolling mill is increased to maintain a sufficient buffer time for exchange of rollers between two rolling campaigns within a casting sequence after transverse separation.
2. The method according to claim 1,
   characterised in
   that a plurality of coils (22) are produced from a multiple length (21).
3. The method according to claim 1,
   characterised in
   that the buffer length (23) of the roller hearth furnace (2) is at least matched to one roller plane (24).
4. The method according to any one of claims 1 to 3,
   characterised in
   that the casting speed (V_c) is reduced by the same amount or greater than that given by the following formula: $$\mathrm{\Delta }\mathrm{V}={\mathrm{V}}_{\mathrm{W}}-\frac{1}{\mathrm{\Delta }\mathrm{t}/\mathrm{L}+1/{\mathrm{V}}_{\mathrm{W}}}\mathrm{\hspace{0.17em}}\left(\mathrm{m}/\min \right)$$

   

   where

   ΔV = reduction in casting speed

   V_w = infeed speed of rolling mill

   Δt = roller exchange time

   L = length of tunnel furnace.
5. The method according to any one of claims 1 to 4,
   characterised in
   that a combination of matching the casting speed (V_c) and the end roll thickness is used to optimise the production capacity.
6. The method according to any one of claims 1 to 5,
   characterised in
   that the end roll thickness is increased at most by a factor of 2.5.
7. The method according to any one of claims 1 to 6,
   characterised in
   that the end roll thickness is increased at most by a factor of 2 and the casting speed (V_c) is reduced to a minimum of 30%.
8. The method according to any one of claims 1 to 7,
   characterised in
   that after the transverse separation, the casting speed (V_c) is reduced and/or the infeed speed (V_w) of the roll trains (3) and/or the end roll thickness are increased, after the end of rolling the worn rollers (3a) of the roll train (3) are changed and after the rollers have been changed, the casting speed (V_c) is increased to the infeed speed (V_w) of the roll train (3).
9. A casting roller plant for the semi-endless or endless rolling of a cast metal or steel strand (1a), which may be transversely separated into casting strip partial lengths (20) in the solidified state and said casting strip partial lengths (20) can be kept warm and equilibrated in a roller hearth furnace (2) and heated to rolling temperature and introduced into a roll train (3) and the continuous casting machine (1) casts continuously, wherein between the continuous casting machine (1) and the roll train (3) there is provided a roller hearth furnace (2) which is designed with a buffer length (23) and which has at least one roller plane, having a transverse separating device (14) located at the input and/or output thereof and wherein the roller hearth furnace (2) is followed by the roll train (3),
   characterised in
   that a descaling device (15) is provided following the transverse separating device (14) and that a separating device (16), a cooling section (17) and reel stations (18) are disposed after the roll train (3); and
   that in at least two roller planes (24) pivoting roller tracks (11) are provided at the entrance (12a) and exit (12b) of the roller hearth furnace (2) each comprising a bending and/or straightening unit.
10. The casting roller plant according to claim 9,
    characterised in
    that multiple lengths (21) can be introduced at a single height level from the exit (9) of the continuous casting machine (1) through the roller track (11) of the roller hearth furnace (2) right into the rolling mill (3a).

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