EP2217394B1 - Method and device for producing a metal strip - Google Patents

Description

The invention relates to a method for producing a strip of metal, in particular of steel, wherein liquid metal is supplied from a pouring opening of a solidification line, wherein the cast metal solidifies along the solidification section, wherein liquid metal at a first location in the form of a horizontally the solidified metal leaves the conveying element at a second location spaced apart in the conveying direction, wherein in the conveying direction behind the second location means are provided, with which the tension in the band is maintained at a desired value, wherein the means or maintain a predetermined tension in the band behind the second location. Furthermore, the invention relates to an apparatus for producing a strip of metal.

With the method of horizontal strip casting, it is possible to cast melts of various steel grades close to the final dimensions in a range of less than 20 mm strip thickness. Systems of this type have already been described with which tapes can be produced. In particular, lightweight steels with a high proportion of C, Mn, Al and Si can be advantageously produced.

In the case of horizontal strip casting of steel, there is a direct connection of material in the liquid phase in the area of the melt application and the further processing steps of the solidified material via the cast strip. The cast strip is fed after solidification and leaving the casting machine on a transport path of further processing. The processing steps can be: straightening, rolling, cutting and unwinding (reeling, coiling).

This or similar components of an overall system can lead to tensile and mass flow fluctuations in the cast strip. Planting the disturbances in the direction of the liquid steel, it may lead to casting defects and negative effects of the cast strip, z. B. thickness variations, overflows, edge constrictions and belt or stall.

In particular, lightweight steels, which may have a very large solidification interval (i.e., temperature window from the onset of solidification from the melt to complete through solidification and zero-toughness temperatures dependent thereon), are additionally intolerant to pull variations even in the transport path.

A method of the type mentioned and a corresponding device are for example from the DE 196 36 699 A1 known. A similar solution shows the WO 2006/066551 A , A corresponding method and an associated device also disclose the contributions of K. Schwerdtfeger et al. "Further results from strip casting with the single-belt process" in ISIJ International 2000 (Iron and Steel Inst. Of Japan), Vol. 40, No. 8, 2000, pages 756 to 764 , and from K.-H. Spitzer et al. "Direct Strip Casting (DSC) - An Option for the Production of New Steel Grades" in Steel Research, Dusseldorf, Vol. 74, No. 11/12, Jan. 1, 2003, pages 724-731 ,

The invention has for its object to provide a method of the type mentioned above and a corresponding device such that it is possible to ensure even with disturbances of the type mentioned that the cast strip has a high quality.

The solution of this problem by the invention according to the method is characterized in that the means at the second location have a driver for the cast strip, that the means further comprise two spaced apart in the conveying direction further driver and that between the Driver at the second location and the forward in the conveying direction further driver extends a transport path, wherein in the transport path a first train level greater than zero is maintained in the band and wherein in the area between the two other drivers a second, higher train level is maintained in the band ,

The means can maintain a temporally constant tension in the band, in particular behind the second location.

In the solidification stretch, a tensile stress of almost zero can be maintained in the strip.

The proposed device for producing a strip of metal, in particular of steel, comprises a pouring opening, with the liquid metal can be fed to a solidification line, wherein the cast metal is transported on the solidification line in a conveying direction on which it solidifies, the solidification section is formed as a horizontally extending conveyor element, wherein the liquid metal can be abandoned at a first location of the solidification line, wherein the solidified metal can leave the conveyor element at a second spaced apart in the conveying direction, wherein in the conveying direction at or behind the second location Means are provided for maintaining a desired tension in the belt. According to the invention, the device is distinguished by the fact that the means at the second location have a driver for the cast strip, that the means furthermore have two further drivers spaced apart from one another in the conveying direction and that there are further drivers between the driver at the second location and the advancing in the conveying direction extends a transport path, wherein means are provided to maintain a first train level greater than zero in the band in the transport path and wherein means are provided to maintain a second, higher train level in the band between the two further drivers.

It is provided in particular that the means for maintaining a desired tension in the belt comprise two drivers, between which the belt can be conveyed in the form of a loop. In this case, a movable roller (in particular dancer roller or loop lifter) can be arranged between the two drivers for the deflection of the belt in the direction of its normal.

Furthermore, it may alternatively be provided that the driver is designed in the form of an S-roller set. A roll of the S-roll set may be slidable in the horizontal direction.

Furthermore, it can be provided that at least one driver is formed by the rolls of a roll stand.

The driver may comprise two cooperating rollers between which the strip leaving the solidification section is located.

The solidification section can be designed as a conveyor belt and the driver can be designed as a roller which presses the belt leaving the solidification section onto a deflection roller of the conveyor belt.

At least one further processing machine may be arranged behind the means for maintaining a desired mass flow. This is, for example, a straightening machine, a rolling mill, a pair of scissors or a reel.

The invention provides facilities and control concepts that largely prevent the negative repercussions from further processing on the cast strip by adjusting and maintaining constant draft and mass flow ratios. This keeps the quality of the cast strip at a high level.

The proposed devices and control concepts to avoid repercussions can consist of two components, namely a strip tension control in combination with a mass flow control.

On the one hand, it can therefore be ensured that a largely constant strip tension is set in the region of the transport path, the mass flow being constant. The strip tension is preferably greater or almost zero on the transport route.

If a strip tension of greater than zero is set in the transport path, the device for strip tension control ensures that the tension in the area of the casting machine (ie on the solidification section) is practically zero. This is necessary because the cast strip can absorb less and less tensile force with increasing temperature and the allowable train becomes zero in the area of liquid purchasing.

In the drawings, embodiments of the invention are shown.

Fig. 1

schematisch eine Vorrichtung zum Herstellen eines Bandes aus Metall mit einer Anzahl Weiterbehandlungsmaschinen,

Fig. 2

eine zu Fig. 1 analoge Ansicht, wobei Mittel zur Aufrechterhaltung eines gewünschten Massenstroms bzw. eines gewünschten Bandzuges in einem hinteren Bereich detaillierter dargestellt sind,

Fig. 3

eine zu Fig. 2 alternative Ausgestaltung der Vorrichtung,

Fig. 4

eine weitere zu Fig. 2 alternative Ausgestaltung der Vorrichtung,

Fig. 5

eine zu Fig. 1 analoge Ansicht, wobei Mittel zur Aufrechterhaltung eines gewünschten Massenstroms bzw. eines gewünschten Bandzuges in einem vorderen Bereich detaillierter dargestellt sind,

Fig. 6

eine zu Fig. 5 alternative Ausgestaltung der Vorrichtung,

Fig. 7

eine weitere Ausgestaltung der Vorrichtung mit Angabe der zu regelnden Größen,

Fig. 8a

den Verlauf der Zugspannung im Band über der Zeit ohne Einsatz des erfindungsgemäßen Vorschlags und

Fig. 8b

den Verlauf der Zugspannung im Band über der Zeit bei Einsatz des erfindungsgemäßen Vorschlags.

Show it:

Fig. 1

1 schematically shows an apparatus for producing a strip of metal with a number of further processing machines,

Fig. 2

one too Fig. 1 similar view, wherein means for maintaining a desired mass flow or a desired strip tension in a rear area are shown in more detail,

Fig. 3

one too Fig. 2 alternative embodiment of the device,

Fig. 4

another one too Fig. 2 alternative embodiment of the device,

Fig. 5

one too Fig. 1 similar view, wherein means for maintaining a desired mass flow or a desired strip tension in a front area are shown in more detail,

Fig. 6

one too Fig. 5 alternative embodiment of the device,

Fig. 7

a further embodiment of the device with indication of the variables to be controlled,

Fig. 8a

the course of the tension in the band over time without the use of the proposal according to the invention and

Fig. 8b

the course of the tension in the band over time when using the proposal according to the invention.

In Fig. 1 is an apparatus for producing a strip 1 by a casting process to see. An essential component of the device is a solidification section 3, which is designed as a conveyor belt 18, by means of two deflection rollers 13 is held in the position shown, wherein the upper side of the conveyor belt 18 is moved in a conveying direction F. At a front in the conveying direction, first place 4 liquid metal from a task vessel 2 on the conveyor belt 18, that is applied to the solidification section 3. In the course of the promotion, the material solidifies and leaves at a second location 5, the conveyor belt 18. The cast strip 1 then passes through a transport path 10 to further processing machines 14, 15, 16, 17, in the present case, a straightening machine 14, a rolling mill 15, a pair of scissors 16 and a reel 17 include.

Core component of the present invention are means 6, 7 for maintaining a desired mass flow of the solidification line 3 leaving belt 1 and / or a desired tension in the belt 1. Preferably, a part of the means 6 in the conveying direction F behind the transport path 10 and part of the means 7 before the transport section 10, but arranged behind the second location 5.

The means 6, 7 are suitable for ensuring that regardless of the process steps that take place in the further processing machines 14, 15, 16, 17, no feedback on the process of strip casting occurs. Rather, the means 6, 7 ensure that a constant mass flow of strip is always drawn off from the solidification section 3 and that the cast strip 1 is then held along the transport path 10 under a predetermined tensile stress.

How this can be done in detail results from the FIGS. 2 to 6 :
In Fig. 2 It can be seen that the means 6 arranged behind the transport path 10 have two drivers 8 and 9 which can be driven in a regulated manner, wherein a dancer roll or a loop lifter 11 is positioned between the drivers 8, 9. This can deflect the band 1 in the direction of the normal N, so that the band assumes a loop-like shape. Dependent on the rotational drive of the driver 8, 9 and the deflection of the dancer roll 11 can be taken to ensure that from the processing machines 14, 15, 16, 17 resulting irregularities are not transmitted to the tape before the means 6. Consequently, the casting process is stabilized and homogenized, so that the casting quality is correspondingly high.

According to this embodiment, the strip tension and mass flow control thus consists of a system of drivers 8, 9 and a movably mounted roller 11 (looper or dancer roll). This makes it possible to run the subsequent process steps at an adjustable Zugniveau in the band. In the region of the means 6 for decoupling the train is adjustable and can be adjusted constantly with the position control of the movably mounted roller 11. About a speed control of the driver 8, 9, the loop height is regulated and thus kept constant the mass flow.

The task of the driver 8 or 9 can optionally also be taken over by a rolling stand.

1. 1. Ist der Treiber 8 nicht angetrieben, fungiert er als Niederhalterrollenpaar. In diesem Falle stellt sich im Bereich der Transportstrecke 10 der gleiche Zug ein wie an der beweglichen Rolle 11 (Schlingenheber, Tänzerrolle).
2. 2. Läuft der Treiber 8 von einem Motor in Momentenregelung angetrieben, kann im Bereich der Transportstrecke 10 ein anderer Zug eingestellt werden, wobei eine nahezu konstante Differenz zwischen einlaufendem und auslaufendem Zug am Treiber besteht.
3. 3. Läuft der Treiber 8 mit Motor angetrieben in Drehzahlregelung, kann im Bereich der Transportstrecke 10 ein nahezu beliebiger anderer Zug im Band eingeregelt werden.

For the mode of operation several variants are possible:

1. 1. If the driver 8 is not driven, it acts as a hold-down roller pair. In this case, in the region of the transport path 10, the same train as at the movable roller 11 (looper, dancer roll).
2. 2. If the driver 8 is driven by a motor in torque control, another train can be set in the area of the transport path 10, with a nearly constant difference between incoming and outgoing train on the driver.
3. 3. If the driver 8 is driven by a motor in speed control, a virtually any other train in the belt can be adjusted in the region of the transport path 10.

One too Fig. 2 alternative embodiment of the invention is in Fig. 3 to see. Here is no dancer role between the two drivers 8 and 9 of the means 6. Rather, here by the drive of the driver 8, 9, the conveying of the belt 1 is controlled or regulated so that to compensate for nonuniformities in the mass flow, a sagging, loop-shaped section of the band 1 between the two drivers 8, 9 is used. The tensile and mass torque coupling is thus achieved here by a free loop of the belt with two speed-controlled drivers 8, 9. Unlike the related Fig. 2 The process runs here without adjustable tension level, the tension is very low in the entire range and results from the weight of the sagging sling. Mass flow fluctuations are compensated by a change in the loop height on the speed control of the driver 8, 9. The strip tension resulting from the weight of the loop can be picked up by the variable-speed driver 8. This can be set via the driver 8, an almost arbitrary train in the transport path. The function of the driver 9 can optionally be taken over again by a rolling stand.

In Fig. 4 is another alternative to see. Here, the tensile and mass torque coupling is achieved by an S-roller set 8 ', 8 "(optionally coupled with a dancer roller) .The lower roller 8" of the S-roller set 8', 8 "can be adjusted in the horizontal direction, which is represented by the With at least one of the speed-controlled S-rollers 8 ', 8 ", the belt tension can be regulated. If a dancer roll is additionally used, it ensures mass flow torque coupling.

In the FIGS. 5 and 6 the means 7 are shown in more detail, which are located in the conveying direction F before the transport path 10.

The funds 7 point in Fig. 5 a driver 12, which consists of two interacting roles. For train control in the band 1 behind the casting machine (pouring opening 2 together with solidification section 3) thus serves the pair of rollers of the driver 12. Can also be provided a plurality of driver pairs. This ensures that the strip tension in the area of the casting machine is practically zero, which is also necessary in the case of the liquid feed since the strip can not absorb any tensile stresses here. The two rollers of the driver 12 press with defined force on the cast strip to produce the frictional engagement. At least one of the driver rollers is speed-controlled.

Alternatively, it can be provided - and this is in Fig. 6 sketched - that the Zugaufnahme takes place via a mounted at the end of the casting machine top roller 12 which presses against one of the deflection rollers 13 of the conveyor belt 18. This is pressed with a force on the tape and the train introduced into the speed-controlled top roller 12 and the speed-controlled cast strip.

In Fig. 7 a further concrete embodiment of the invention is shown. Here is a speed and tension control according to the type of solution according to the above Figures 2 and 6 intended. There is a combination of tension control and mass torque coupling, wherein in the region of the means 6, two drivers 8 and 9 is provided with interposed dancer roller 11; In the region of the means 7, a driver roller 12 is provided, which presses on a deflection roller 13 of the conveyor belt 18. In this embodiment, the drivers are speed controlled, wherein the driver 9 via the loop control (by means of the dancer roller 11) keeps the mass flow constant. The positioning of the loop lifter (dancer roll 11) controls the strip tension constantly. The driver 8 is speed-controlled with superimposed tension control and ensures a constantly adjustable tension level in the area of the belt transport. The strip tension applied here is introduced via the resting and pressing top roller 12 into the engine torque of the upper roller.

While in the region of the solidification section 3 there is a strip tension of substantially zero, the strip tension in the region of the transport path 10 is significantly greater than zero. Behind the driver 8 may be an even higher train level.

While the driver roller 12 is speed controlled under specification of the speed, a speed default velvet tape default in the case of the driver 8 leads to a speed and Antriebsdrehmoment- and thus tension control. The tension control by means of the dancer roller 11 leads to a regulation of the pivoting angle of the arm on which the dancer roll sits and thus on the regulation of the operating force of the arm to a tension control. Driver 9 is speed-controlled with superimposed loop and thus mass flow control.

In Fig. 8 the comparison of the time course of the tension in the band 1 in the area of the belt transport after the casting machine can be seen, in Fig. 8a for a previously known solution, in Fig. 8b for an embodiment according to the invention.

The effect on the tension in the belt is due to the operation of a pair of scissors 16 (s. Fig. 1 ) as part of a further processing section. The scissors 16 performs a cut, which results in a deviation from the ideal constant band movement in the band transport. The scissors 16 pulls during the cut namely on the belt 1, so that without the inventive solution according to Fig. 8a high trains in the field of tape transport occur, which can propagate in the direction of the liquid phase and lead to the problems mentioned above.

Using the solution according to the invention can according to Fig. 8b the strip tension are kept almost constant at the same disturbance. Faults in the casting process can be largely avoided, they are in any case significantly lower than in Fig. 8a ,

LIST OF REFERENCE NUMBERS

1

tape

2

task vessel

3

solidification path

4

first place

5

second place

6, 7

Means for maintaining a desired mass flow and for tension control

8th

driver

8th'

Roll of the S-roll set

8th"

Roll of the S-roll set

9

driver

10

transport distance

11

movable role (dancer role)

12

driver

13

idler pulley

14

Further processing machine (straightening machine)

15

Further processing machine (rolling mill)

16

Further processing machine (scissors)

17

Further processing machine (reel)

18

conveyor belt

F

conveying direction

N

normal

Claims (17)

1. Method of producing a strip (1) of metal, particularly of steel, wherein liquid metal is fed from a pouring opening (2) to a hardening path (3), the cast metal solidifies along the hardening path (3), liquid metal is delivered at a first location (4) to the hardening path (3), which is constructed in the form of a horizontally extending conveyor element, the solidified metal leaves the conveyor element (3) at a second location (5) spaced in conveying direction (F), means (6, 7) by which the tension in the strip is kept to a desired value are provided behind the second location (5) in conveying direction (F) and the means (6, 7) maintain a predetermined tension in the strip (1) at or behind the second location (5),
   characterised in that
   the means (7) at the second location (5) comprise a driver (12) for the cast strip (1), the means (6) further comprise two further drivers (8, 9) spaced from one another in conveying direction (F) and a transport path (10) extends between the driver (12) at the second location (5) and the further driver (8) at the front in conveying direction (F), wherein a first tension level greater than zero is maintained in the strip (1) in the region of the transport path (10) and wherein a second, higher tension level is maintained in the strip (1) in the region between the two further drivers (8, 9).
2. Method according to claim 1, characterised in that the means (6, 7) maintain a tension, which is almost constant in terms of time, in the strip (1) at or behind the second location.
3. Method according to claim 1 or 2, characterised in that a tension of almost zero is maintained in the strip (1) in the hardening path (3).
4. Device for producing a strip (1) of metal, particularly from steel, wherein the device comprises a delivery vessel (2) by which liquid metal can be fed to a hardening path (3), wherein the cast metal is transported in a conveying direction (F) on the hardening path (3) on which it solidifies, the hardening path (3) is constructed as a conveyor element extending in horizontal direction, the liquid metal can be delivered at a first location (4) to the hardening path (3), the solidified metal can leave the conveyor element (3) at a second location (5) spaced in conveying direction (F), and means (6, 7) for maintaining tension in the strip (1) are present at or behind the second location (5) in conveying direction (F), particularly for carrying out the method according to any one of claims 1 to 3, characterised in that
   the means (7) at the second location (5) comprise a driver (12) for the cast strip (1), the means (6) further comprise two further drivers (8, 9) spaced from one another in conveying direction (F) and a transport path (10) extends between the driver (12) at the second location (5) and the further driver (8) at the front in conveying direction (F), wherein means are present in order to maintain a first tension level in the strip (1) greater than zero in the region of the transport path (10) and wherein means are present in order to maintain a second, higher tension level in the strip (1) in the region between the two further drivers (8, 9).
5. Device according to claim 4, characterised in that the means (6, 7) for maintaining a desired tension in the strip (1) comprise two drivers (8, 9) between which the strip (1) can be conveyed in the form of a loop.
6. Device according to claim 5, characterised in that a movable roller (11) for deflecting the strip in the direction of its normal (N) is arranged between the two drivers (8, 9).
7. Device according to claim 4, characterised in that the driver (8) is constructed in the form of an S-roller set (8', 8").
8. Device according to claim 7, characterised in that a roller (8") of the S-roller set (8', 8") is arranged to be displaceable in horizontal direction.
9. Device according to claim 4, characterised in that the at least one driver (8, 9) is formed by the rolls of a roll stand.
10. Device according to claim 4, characterised in that the driver (12) comprises two cooperating rollers between which the strip (1) leaving the hardening path (3) is arranged.
11. Device according to claim 4, characterised in that the hardening path (3) is constructed as a conveyor belt (18) and the driver (12) as a roller which presses the strip (1) leaving the hardening path (3) onto a deflecting roller (13) of the conveyor belt (18).
12. Device according to any one of claims 4 to 11, characterised in that at least one further processing machine (14, 15, 16, 17) is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).
13. Device according to claim 12, characterised in that at least one straightening machine (14) is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).
14. Device according to claim 12 or 13, characterised in that at least one rolling mill (15) is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).
15. Device according to claim 12, 13 or 14, characterised in that at least one shears (16) is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).
16. Device according to any one of claims 12 to 15, characterised in that at least one coiler (17) is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).
17. Device according to any one of claims 12 to 15, characterised in that at least one stacking installation for stacking strip sections is arranged behind the means (6, 7) for maintaining a desired tension in the strip (1).

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