DE10249704A1 - Process and casting rolling plant for semi-endless rolling or continuous rolling by casting a metal, in particular a steel strand, which is cross-divided after solidification if necessary - Google Patents

Abstract

A method and a casting and rolling plant for semi or endless rolling by casting a metal, in particular a steel strand (1a), which is cross-divided after solidification, if necessary, the partial casting lengths (20) in a roller hearth furnace (2) for heating and leveling Rolling temperature are performed, and the partial lengths (20) for rolling into a rolling mill (3) are introduced, the continuous casting being continued without interruption during the rolling operation, can be exerted in a closer adaptation between continuous casting and rolling, by changing the casting speed for a roll change ( V¶c¶) is lowered in such a way that a sufficient buffer time for a roll change is maintained between the end of the rolling of a previous multiple length (21) and the piercing of a new partial length (20) or multiple length (21) in the rolling mill.

Description

The invention relates to a method and a casting mill for semi-continuous rolling or continuous rolling by casting one Metal, especially a steel strand, after solidification if necessary, the part of the casting strand is divided into a roller hearth furnace for heating and equalizing to rolling temperature guided and the partial lengths with rolling temperature to be rolled into a rolling mill, being the continuous casting while of the rolling operation is continued without interruption.

Such a method is known from the EP 0 264 459 B1 known. In this process, the partial lengths of the casting strand are stored in the tunnel furnace with transverse transport.

The casting strand partial lengths are over one Period saved that is a multiple, e.g. four times, their casting time equivalent. The process is also carried out in such a way that the rolling of each individual part of the casting strand performed in a unit of time which is only a fraction, e.g. corresponds to a fifth of its casting time, and in that the rolling is carried out discontinuously and the rolling process over a period that is the difference between a casting time and corresponds to a rolling, is interrupted with a pause. This process strictly depends on the continuous casting and is not matched to the rolling process.

The invention is based on the object the semi-endless rolling and the endless rolling more on the conditions during rolling to coordinate the rolling process with the continuous casting process adapt.

The object is achieved according to the invention solved, that for a roll change the casting speed is lowered such that between the end of the rolling of the previous one Multiple length and piercing a new partial or multiple length in the rolling mill sufficient buffer time for a roll change is observed. This makes semi-continuous rolling and adapted the continuous rolling to the conditions of the rolling and it becomes a buffer time for created the inevitable roller change.

By semi or endless rolling resulting larger lengths of rolled stock thereby taken into account that from a multiple length multiple coils are generated.

The buffer time for the roll change can still be be influenced by the fact that the casting speed is dependent the feed speed of the rolling mill and / or the roll change time including the calibration time and / or the buffer length of the roller hearth furnace and / or the final roll thickness after cross-cutting is reduced.

According to another characteristic, it is proposed that the buffer length the roller hearth furnace is matched to at least one roller level.

bedeuten:
ΔV = Gießgeschwindigkeitsreduzierung
V_w = Einzugsgeschwindigkeit des Walzwerks
Δt = Walzenwechselzeit und
L = Länge des Tunnelofens.In order to achieve the desired buffer time, it is also advantageous that the casting speed V _c , which corresponds to the feed speed V _{w of} the rolling mill, is reduced to the same or greater according to the following formula:

mean:
ΔV = casting speed reduction
V _w = feed speed of the rolling mill
Δt = roll change time and
L = length of the tunnel kiln.

This can save even more time be achieved between rolling campaigns within a casting sequence after cross cutting the final roll thickness and / or the feed speed of the rolling mill increased becomes.

There is also an embodiment in that a combination of adjusting the casting speed and the final roll thickness to optimize production performance becomes.

It is also an advantage if the Final roll thickness is increased by a maximum of 2.5 times.

Another buffer time can be achieved in that the final roll thickness by a maximum of Factor 2 is increased and the casting speed is reduced to a minimum of 30%.

The process can be done according to a practical Example can be applied in such a way that after cross-cutting the casting speed is reduced and / or the feed speed of the rolling mill and / or the final rolling thickness increases the worn rollers of the rolling mill are changed after the rolling has ended and after the roll change, the casting speed to the feed speed the rolling mill is increased.

The one required to carry out the procedure continuous casting and rolling for semi-continuous rolling or continuous rolling of a cast metal or steel strand, the in the solidified state can be divided into partial lengths of the casting strand if required and the casting strand partial lengths in a roller hearth oven can be kept warm and heated to rolling temperature and comparable and insertable into a rolling mill the sequential arrangement of the continuous casting machine, a cross-section device, a roller hearth furnace, further auxiliary devices, a rolling mill and at the end of a reel.

The casting and rolling system can then the method described above operated between the continuous casting machine and the rolling mill a roller hearth furnace with at least one roller level, at the entrance and / or output a cross-section device, hereinafter a descaling device are provided, followed by the rolling mill and one behind the rolling mill Separator, a cooling section and reel systems are arranged.

There is an embodiment in that at least two roller levels swivel roller tracks at the entrance and exit of the roller hearth furnace, each with a bending and / or straightening unit are arranged. The extrudate can be guided precisely into the respective role level.

The strand guide can also do this be trained that multiple lengths at a single height level from the exit of the continuous caster can be inserted into the rolling mill through the roller conveyor of the roller hearth furnace.

Exemplary embodiments are shown in the drawing presented the invention, the following process and device technology are explained in more detail.

Show it:

1 the casting and rolling plant with a roller hearth furnace and a roller level in side view,

2A a partial side view with a casting strand, wherein the casting speed is equal to or less than the rolling speed,

2 B the same view with the transport speed of a casting strand part length increased to the rolling speed,

3A continuous casting and rolling at the same casting and rolling speed and with two coiler systems,

3B continuous casting and rolling with the two coiler lines,

4A the situation when changing rolls and reduced casting speed,

4B the situation after the roll change and increased casting speed and

5 the casting and rolling machine in side view like 1 for an alternative embodiment.

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

In the continuous casting machine 1 becomes a tundish from a ladle (not shown) 4 fed, which a continuous casting mold 5 , a support roller stand 6 with a bending unit 7 and a straightener 8th are subordinate. At the exit 9 is a cross dividing device 10 and behind this (as an alternative in 5 ) a swiveling roller conveyor 11 for the entrance 12a the roller hearth furnace 2 ordered on. At the exit 12b there is again a swiveling roller conveyor 13 and a cross dividing device 14 , The basic embodiment in 1 works without the swiveling roller conveyors 11 . 13 ,

The rolling mill 3 starts after the cross dividing device 14 with a descaling device 15 , This is followed by the rolling mill 3 with about five to seven roll stands. Behind the rolling stands are a separator 16 a cooling section 17 and following this two reelers 18 intended.

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

In the event that the rollers 3a are worn out, the casting speed V _{c is} lowered for a roll change in such a way that between the end of rolling a previous multiple length 21 and piercing a new part length 20 or multiple lengths 21 in the rolling mill 3 there is sufficient buffer time for changing the rollers. From the multiple length 21 can have multiple coils 22 be wrapped.

The casting speed V _c is, for example, dependent on the feed speed V _{w of} the rolling mill 3 and / or the respective roll change time including a calibration time and / or the buffer length 23 the roller hearth furnace 2 and / or the final roll thickness after cross-cutting is reduced. The buffer length 23 the roller hearth furnace 2 can at least at a role level 24 be coordinated (cf. 1 ).

In 2A the casting speed V _c becomes equal to or less than the drawing speed V _w into the rolling mill 3 set. Once the roller hearth furnace 2 is loaded, the speed V _c can be raised again to the feed speed V _w , as in 2 B is shown.

In 3A continuous rolling is shown. The casting strand 1a is guided and rolled at the casting speed V _c , which is equal to the drawing speed V _w into the first roll stand, then cooled, wound and in the separating device 16 cut. After a cross division in the cross dividing device 10 can the casting strand 1a , as in 3B is shown, are poured at a reduced casting speed V _c and the separated part of the casting strand 20 is rolled and wound at feed speed V _w .

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 according to the following formula:

where mean:
ΔV = casting speed reduction (m / min)
V _w = feed speed of the rolling mill (m / min)
Δt = roll change time (min)
L = length of the tunnel furnace (m).

With a feed speed V _w = 10 m / min, a roll change time Δt = 10 min and a roller hearth length L = 200 m, the casting speed V _c must be reduced by at least 3.33 m / min.

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

Between the rolling campaigns within a casting sequence, the final rolling thickness and / or the feed speed V _{w of} the rolling mill can be used after the cross-cutting 3 increase.

However, a combination of an adjustment of the casting speed V _c and the final rolling thickness can also be used to optimize the production performance. The final roll thickness can be increased by a maximum of 2.5 times. Another option is that the final roll thickness is increased by a maximum of a factor of 2 and the casting speed is reduced to a minimum of 30%.

In a further exemplary embodiment it is provided that the casting speed V _{c is} reduced after the cross-cutting and / or the drawing-in speed V _{w of} the rolling mill 3 and / or the final roll thickness can be increased after the rolling is finished, the worn rolls 3a the rolling mill 3 be changed and after the roll change, the casting speed V _c to the feed speed V _{w of} the rolling mill 3 is increased.

The casting and rolling system for semi-continuous rolling or continuous rolling of a cast metal or steel strand, which is used as a casting strand 1a in the solidified state, if necessary, in partial lengths 20 is divisible and the casting strand partial lengths 20 in a roller hearth furnace 2 kept warm and heated to rolling temperature and evened out and then into a rolling mill 3 be introduced requires that on the continuous casting machine 1 is continuously poured. To do this is between the continuous casting machine 1 and the rolling mill 3 the roller hearth furnace 2 with at least one role level 24 , at its entrance 12a and or output 12b a cross dividing device 14 , hereinafter a descaling device 15 are provided, followed by the first rolling stand and behind the rolling mill 3 the separator 16 , Cooling section 17 and reelers 18 are arranged.

The roller conveyors on the inlet and outlet side 11 . 13 have bending and / or straightening units 7 . 8th on the respective role level 24 can be aligned or set up. So are the swiveling roller conveyors 11 . 13 at the entrance 12a and at the exit 12b the roller hearth furnace 2 with at least two role levels 24 , each with a bending and / or straightening unit 7 . 8th provided (cf. 5 ).

According to the alternative construction in 5 can be multiple lengths 21 on several role levels 24 from the exit 9 the continuous casting machine 1 thanks to the swiveling roller conveyor 11 the roller hearth furnace 2 via the swiveling roller conveyor 13 to the rolling mill 3 be performed.

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 (13)

Process for semi-continuous rolling or continuous rolling by casting a metal, in particular a steel strand ( 1a ), which is cross-divided after solidification if necessary, the casting strand partial lengths ( 20 ) in a roller hearth furnace ( 2 ) for heating and evening to the rolling temperature, and the partial lengths ( 20 ) with rolling temperature for rolling into a rolling mill ( 3 ) are introduced, the continuous casting being continued without interruption during the rolling operation, characterized in that for a roll change the casting speed (V _c ) is reduced in such a way that between the end of the rolling a previous multiple length ( 21 ) and the piercing of a new part length ( 20 ) or multiple lengths ( 21 ) there is sufficient buffer time in the rolling mill for a roll change. A method according to claim 1, characterized in that from a multiple length ( 21 ) several coils ( 22 ) be generated. Method according to one of claims 1 or 2, characterized in that the casting speed (V _c ) as a function of the feed speed (V _w ) of the rolling train ( 3 ) and / or the roll change time including the calibration time and the buffer length of the roller hearth furnace ( 2 ) and / or the final roll thickness after the cross-cutting is reduced. A method according to claim 1, characterized in that the buffer length ( 23 ) of the roller hearth furnace ( 2 ) at least on a role level ( 24 ) is coordinated. Method according to one of claims 1 to 4, characterized in that the casting speed (V _c ) is reduced equal to or greater according to the following formula:

with ΔV = casting speed reduction V _w = feed speed of the rolling mill Δt = roll change time L = length of the tunnel furnace. Method according to one of claims 1 to 5, characterized in that between rolling campaigns within a casting sequence after cross-cutting, the final roll thickness and / or the feed speed (V _w ) of the rolling mill is increased. A method according to claim 6, characterized in that a combination of an adjustment of the casting speed (V _c ) and the final rolling thickness is used to optimize the production output. Method according to one of claims 6 or 7, characterized in that that the final rolling thickness is increased by a maximum of 2.5 times. Method according to one of claims 6 or 7, characterized in that the final rolling thickness is increased by a maximum of a factor of 2 and the casting speed (V _c ) is reduced to a minimum of 30%. Method according to one of claims 1 to 9, characterized in that after the cross-cutting, the casting speed (V _c ) is reduced and / or the drawing-in speed (V _w ) of the rolling train ( 3 ) and / or the final roll thickness can be increased, after the rolling has ended, the worn rolls ( 3a ) of the rolling mill ( 3 ) and after the roll has been changed, the casting speed (V _c ) to the feed speed (V _w ) of the rolling mill ( 3 ) is increased. Casting-rolling plant for semi-continuous rolling or continuous rolling of a cast metal or steel strand ( 1a ), which in the solidified state can be cast in partial lengths if required ( 20 ) can be split and the casting strand partial lengths ( 20 ) in a roller hearth furnace ( 2 ) can be kept warm and heated up to the rolling temperature and is comparable and placed in a rolling mill ( 3 ) are insertable and the continuous casting machine ( 1 ) continuously pouring, characterized in that between the continuous casting machine ( 1 ) and the rolling mill ( 3 ) a roller hearth furnace ( 2 ) with at least one role level ( 24 ), at the entrance ( 12a ) and / or output ( 12b ) a cross dividing device ( 14 ), hereinafter a descaling device ( 15 ), the rolling mill ( 3 ) follows and behind the rolling mill ( 3 ) a separator ( 16 ), a cooling section ( 17 ) and reel systems ( 18 ) are arranged. Casting-rolling plant according to claim 11, characterized in that with at least two roller levels ( 24 ) swiveling roller conveyors ( 11 ) at the entrance ( 12a ) and exit ( 12b ) of the roller hearth furnace ( 2 ), each with a bending and / or straightening unit. Casting-rolling plant according to one of claims 11 or 12, characterized in that multiple lengths ( 21 ) at a single height level from the exit ( 9 ) of the continuous casting machine ( 1 ) through the roller conveyor ( 11 ) of the roller hearth furnace ( 2 ) into the rolling mill ( 3a ) can be introduced.