EP3504013B1 - Method for producing a metal strip in a cast-rolling installation - Google Patents

Description

• eine Gießmaschine zum Gießen einer Bramme,
• einen in Förderrichtung des metallischen Bandes der Gießmaschine folgender erster Ofen oder/und eine erste Rollgangsdämmstrecke,
• eine erste Schere, die zwischen der Gießmaschine und dem ersten Ofen oder/und der ersten Rollgangsdämmstrecke angeordnet ist,
• eine Vorstraße mit einer Anzahl Walzgerüste,
• einen in Förderrichtung des metallischen Bandes der Vorstraße folgender zweiten Ofen oder/und eine zweite Rollgangsdämmstrecke,
• eine zweite Schere, die zwischen der Vorstraße und dem zweiten Ofen oder/und der zweiten Rollgangsdämmstrecke angeordnet ist,
• eine Fertigstraße mit einer Anzahl Walzgerüste,
• eine Kühlstrecke,
• mindestens zwei Haspel oder einen Wendehaspel und
• eine dritte Schere, die zwischen der Kühlstrecke und der Haspelanlage angeordnet ist.

The invention relates to a method for producing a metallic strip in a casting and rolling plant, the casting and rolling plant comprising:

• a casting machine for casting a slab,
• a first furnace and / or a first roller table insulation section following in the conveying direction of the metallic strip of the casting machine,
• a first pair of scissors, which is arranged between the casting machine and the first furnace and / or the first roller table insulation section,
• a roughing train with a number of roll stands,
• a second furnace following the roughing train in the conveying direction of the metallic strip and / or a second roller table insulation section,
• a second shear, which is arranged between the roughing train and the second furnace and / or the second roller table insulation section,
• a finishing train with a number of rolling stands,
• a cooling section,
• at least two reels or a turning reel and
• a third pair of scissors, which is arranged between the cooling section and the reel system.

The requirements for the flexible operation of thin slab casting and rolling plants (CSP plants) are constantly increasing. The aim is that different operating conditions can be set. Adaptation, for example, to the rolled finished strip thickness or to the casting speed is also desirable for reasons of quality and energy consumption.

Thin-slab casting and rolling plants for rolling individual strips or for endless rolling have already been mentioned in the prior art. For example, the DE 195 18 144 C2 , on the DE 196 13 718 C1 , on the EP 0 870 553 B1 , on the WO 2007/073841 A1 , on the WO 2009/012963 A1 and on the EP 2 569 104 B1 pointed out. Further solutions, some of which also use different operating modes, are available from the US 2011/272116 A1 and from the WO 00/10741 A1 famous. The preamble of claim 1 is based on US 2011/272116 A1 .

However, the previously known solutions sometimes have disadvantages in terms of flexibility.

The invention is therefore based on the object of further developing a method of the type mentioned above in such a way that an increased degree of flexibility is possible; in particular, it should be possible to react flexibly to different operating conditions. The proposed system concept and the mode of operation should therefore be characterized by a high degree of flexibility.

This object is achieved by the method according to claim 1.

At least one slab is preferably placed in the first furnace and / or in the first roller table insulation section. At least one slab or pre-strip is also preferably placed in the second furnace and / or in the second roller table insulation section.

The above-mentioned operating modes a), b), c) and / or d) can be selected depending on the final thickness of the strip. It is also possible that the operating modes a), b), c) and / or d) are selected depending on the start-up process of the casting and rolling plant. It is also possible for the operating modes a), b), c) and / or d) to be selected as a function of a roll change taking place in the roughing train and / or in the finishing train.

First one of the mentioned operating modes is selected and production is then carried out with this mode; accordingly, only one of the mentioned possibilities a), b), c) or d) is realized at a given time. However, it is also possible to switch between the various operating modes mentioned one after the other.

The mean slab temperature at the outlet of the first furnace is preferably at least 1,000 ° C, particularly preferably at least 1,100 ° C.

The mean pre-strip temperature at the outlet of the second furnace is preferably at least 1,100 ° C., particularly preferably at least 1,150 ° C.

mit h_V als der Vorbanddicke und h_F als der Fertigbanddicke. Speziell in diesem Falle ist bevorzugt vorgesehen, dass die mittlere Vorbandtemperatur am Auslauf des zweiten Ofens mindestens 1.150 °C beträgt, wobei das Produkt aus Dicke des Bandes (h_B) und Geschwindigkeit des Bandes (v_B) mindestens 350 mm m/min beträgt, vorzugsweise mindestens 500 mm m/min.A further development stipulates that the degree of deformation of the strip in the finishing train is: $$\mathrm{\epsilon }=\left({\mathrm{H}}_{\mathrm{V}}-{\mathrm{H}}_{\mathrm{F.}}\right)/{\mathrm{H}}_{\mathrm{V}}\times 100\ge 96\%$$

with h _V as the pre-strip thickness and h _F as the finished strip thickness. Especially in this case, it is preferred that the average pre-strip temperature at the outlet of the second furnace is at least 1,150 ° C, the product of the thickness of the strip (h _B ) and the speed of the strip (v _B ) being at least 350 mm m / min, preferably at least 500 mm m / min.

It is preferably provided that, in the procedure described, there is no inductive heating of the slab and / or the pre-strip.

The temperature in the last active stand of the finishing train is preferably above the γ-α phase transition, in particular above 820 ° C.

An exemplary embodiment of the invention is shown in the drawing. The single figure shows schematically the side view of a 1-strand casting and rolling plant for the production of a strip.

The proposed thin slab casting and rolling plant concept consists of the following main components, which can be seen from the figure:
The casting and rolling plant 2 for producing the strip 1 initially has a casting machine 3. A first furnace 4 is arranged downstream of the casting machine 3 in the conveying direction F of the material; the first furnace 4 is followed in the conveying direction F by a roughing train 5 which has a number of roll stands R1 and R2. Behind the roughing train 5 follows a second furnace 6, which in turn is followed by a finishing train 7 with several roll stands F1, F2, F3, F4, F5, F6. A cooling section 8 is arranged behind the finishing train 7, followed by a reel 9.

A first pair of scissors S1 is arranged between the casting machine 3 and the first furnace 4. A second pair of shears S2 is located behind the roughing train 5 and in front of the second furnace 6. Finally, a third pair of shears S3 is located just in front of the reel 9.

There is space for at least one single slab in the first furnace 4 and / or in the first roller table insulation section; the at least one single slab is also provided in the area between the first shears S1 and the first roll stand R1 of the roughing train 5 fits. The roughing train 5 preferably consists of 1 to 4 stands, with two stands being particularly preferably provided.

The second furnace 6 and / or the second roller table insulation section behind the roughing train 5 is designed so that there is space for at least one single sliver in its horizontal position or extent or at least one sliver in the area between the second shears S2 and the first roll stand F1 the finishing mill 7 fits. The finishing train 7 usually consists of 1 to 7 stands, preferably 4 to 6 stands are provided.

The first shears S1 are slab shears for cutting the slabs leaving the casting machine 3. The second shear S2 is a sliver shear for cutting the sliver behind the roughing train 5 and is preferably arranged in front of the second furnace 6. Finally, the third shears S3 are band shears for cutting the bands in front of the reel 9.

Accordingly, the three scissors S1, S2 and S3 are provided in order to be able to implement the different operating modes mentioned above.

In the casting and rolling plant 1, there is preferably no rapid heating (for example in the form of induction heating), which is advantageous when using less expensive gas and from an energetic point of view.

Instead of the first furnace 4 and / or the second furnace 6 (for example and preferably in the form of a roller hearth furnace), roller table insulation sections can alternatively be provided in which there is space for at least one single slab or a single pre-strip; In this case, induction heating can also optionally be arranged behind said roller table insulation sections. An arrangement of furnace parts and roller table insulation sections in any order and combination in front of and / or behind the roughing train is also possible.

The length of the first oven (4) or the first roller table insulation section or an arrangement of first oven parts (4) and roller table insulation sections in any order and combination behind the first scissors (S1) is preferably shorter than the length of the second oven (6) or the second Roller table insulation section or an arrangement of second furnace parts (6) and roller table insulation sections in any order and combination behind the second scissors (S2).

A single slab or a single pre-strip is so long that a coil with a typically produced ring weight can be rolled or produced from it.

The casting and rolling plant (CSP plant) can be operated very flexibly thanks to the optimized operation of the main components mentioned. Various operating modes can be used in the roughing train, in the finishing train or in the entire system:
According to method mode a) mentioned above, endless rolling in roughing train 5 and endless rolling in finishing train 7 are initially possible, ie in this case the casting machine 3 and the roughing and finishing train 5, 7 are connected to one another. It is rolled with the casting machine mass flow and the strips on the reel 9 are separated with the third scissors S3.

According to method mode b) mentioned above, continuous rolling in roughing train 5 with casting machine mass flow and single strip rolling (batch operation) in finishing train 7 is also possible. Here, the individual pre-strips are cut on the second shear S2. The mass flow in the finishing train 7 is higher during rolling than in the roughing train 5 or connected casting machine 3. This results in a combination of the advantages of continuous rolling in the relevant first stands with relatively high degrees of deformation as well as better pre-strip geometry at the top and bottom with the advantages of the batch rolling in the finishing train 7 and the higher final rolling temperatures that can be achieved therewith.

According to the above-mentioned method mode c), single strip rolling (batch operation) in roughing train 5 and single strip rolling (batch operation) in finishing train 7 are also possible. Here, the individual slabs are separated on the first shear S1. The roughing train 5 and the finishing train 7 are both operated with a higher mass flow than the casting machine 3 during the rolling process. The temperature control can be influenced as desired by an individual selection of the speed of the rolling trains.

According to the above-mentioned method mode d), a further operation is finally possible: If the first furnace 4 and the second furnace 6 or the distances between the first shears S1 and the roll stand R1 of the roughing train 5 and / or the second shears S2 and roll stand F1 are the Finishing train 7 dimensioned so long that it can accommodate more than one slab (for example 2 or 3 slabs), then a semi-endless strip rolling from the first furnace 4 and / or the second furnace 6 or the corresponding plant sections is possible. The semi-endless slabs are then first separated on the first shear S1 or semi-endless pre-strips on the second shear S2 and a final division into individual strips with the third shear S3 in front of the coiler 9.

The various operating modes can be selected and set depending on the final thickness or when the system is started up (at the start of casting) or before a roll change or for temperature reasons. A warm-up of the rolling mills can, for. B. be done in batch mode on roughing and finishing mills. Then you can first switch to endless mode in the roughing train. For strips that are becoming thinner (preferably with thicknesses of less than or equal to 1.2 mm), continuous strip rolling is recommended for the roughing and finishing train. If a roll change is only planned in the finishing train, the batch mode is switched to for the finishing train.

In order to gain the change time for the work roll change in the finishing train, rolling is advantageously carried out at increased strip speed and / or temperature speed-up in the finishing train and / or the casting speed as well Rolling speed in the roughing train reduced. In order to compensate for different slab and / or pre-strip temperatures over the strip length during batch rolling and to generate as constant as possible finished strip temperatures downstream of the finishing train, the roughing train and / or the finishing train are operated with temperature speed-up or, alternatively, the amount of water in at least one intermediate stand is cooled changed accordingly.

An extension of the flexibility is thus possible with the proposed system.

The proposed casting and rolling plant (CSP plant) is characterized by various advantageous technical facilities and operating conditions:
There is an optimal arrangement of a slab cleaning (or descaling) at the outlet of the casting machine 3 (less than 2 m) behind the last strand roll. Alternatively, the slab is cleaned (descaled) between the last two pairs of strand rolls.

A roller table insulation between the casting machine 3 or slab cleaning up to the entrance of the first furnace 4 is advantageous. The insulation can be swiveled in in the area of the first scissors S1. This minimizes energy and temperature losses in this transport area.

The use of compact, single-row descaling bars with a minimized specific amount of descaling water V _spec with the following condition is preferred:
V _spec in m ³ / h / m <600 xv, preferably V _spec in m ³ / h / m <450 xv
with v as the transport speed of the rolled or cast product in the area of the scale washer in m / s ("x" is the multiplication symbol).

The active number of finishing stands n is preferably adapted to the finished strip thickness h _F. The following approximation equation is used for this: $$\mathrm{n}\ge 5\times {{\mathrm{H}}_{\mathrm{F.}}}^{-0.6}$$

This means that in the case of thicker final strip thicknesses, 1, 2 or 3 stands are opened starting with the last finishing stands in order to obtain the correct final rolling temperature for the finished strip. In order to produce a good strip quality here, strip cooling is preferably started within the finishing train behind the last active stand. Pyrometers between the last finishing stands monitor the setting of the correct final rolling temperature and are used for control purposes.

The respective first furnace 4 and / or second furnace 6 or corresponding roller table areas with insulation can be divided into different areas (in the longitudinal direction) so that slabs or slab parts and / and pre-strips or pre-strip parts can be conveyed out. This allows z. B. Buffer times created, the cold strand simply disposed of or the elimination of malfunctions simplified. In addition, flame cutting machines can be provided in front of and / or behind the furnace parts.

The mean slab temperature (definition: averaged over the thickness in the middle) at the outlet of the first furnace 4 is 1,000 ° C, preferably 1,100 ° C.

The mean pre-strip temperature at the exit from the second furnace 6 is 1,100 ° C, preferably 1,150 ° C.

(mit h_V = Vorbanddicke, h_F = Fertigbanddicke) in der Fertigstraße kombiniert mit einer hohen Vorbandtemperatur von ≥ 1.150°C (am Austritt aus dem zweiten Ofen 6) und einem hohen Massenfluss in m/min mm von h_B x v_B ≥ 350 m/min mm (vorzugsweise h_B x v_B ≥ 500 m/min mm) oder allgemein mit der Bedingung abhängig von der Gerüstanzahl $$2.316\times {\mathrm{h}}_{\mathrm{B}}\times {\mathrm{v}}_{\mathrm{B}}\times {\mathrm{e}}^{\left(-0.167\times \mathrm{n}\right)}\ge 480\mathrm{m}/\min \mathrm{mm}$$

(mit n = Gerüstanzahl, h_B = Brammendicke mm, v_B = Brammengeschwindigkeit m/min) kann auch in der Regel beim Endloswalzen auf eine induktive Nachheizung innerhalb der Fertigstraße verzichtet und die Anlage vorteilhaft betrieben werden, so dass die Umformung im letzten aktiven Fertiggerüst oberhalb der γ-α-Phasenumwandlung (z.B. 820°C) stattfindet. Optional ist eine induktive Erwärmung innerhalb der Fertigstraße zwischen den Fertiggerüsten für den Betriebsmode Endloswalzen oder Semi-Endloswalzen zur Einstellung höherer Endwalztemperaturen (z.B. ≥850°C) oder/und gezielter Beeinflussung der mechanischen Fertigbandeigenschaften oder/und bei niedrigen Gießgeschwindigkeiten angedacht.Through a high forming (total finishing line forming) $$\mathrm{\epsilon }=\left({\mathrm{H}}_{\mathrm{V}}-{\mathrm{H}}_{\mathrm{F.}}\right)/{\mathrm{H}}_{\mathrm{V}}\times 100\ge 96\%$$

(with h _V = pre-strip thickness, h _F = finished strip thickness) in the finishing train combined with a high pre-strip temperature of ≥ 1,150 ° C (at the exit from the second furnace 6) and a high mass flow in m / min mm of h _B xv _B ≥ 350 m / min mm (preferably h _W xv _W ≥ 500 m / min mm) or generally with the condition depending on the number of stands $$\mathrm{2,316}\times {\mathrm{H}}_{\mathrm{B.}}\times {\mathrm{v}}_{\mathrm{B.}}\times {\mathrm{e}}^{\left(-0.167\times \mathrm{n}\right)}\ge 480\mathrm{m}/\min \mathrm{mm}$$

(with n = number of stands, h _B = slab thickness mm, v _B = slab speed m / min), inductive reheating within the finishing train can usually be dispensed with during continuous rolling and the system can be operated advantageously so that the forming takes place in the last active finishing stand takes place above the γ-α phase transition (e.g. 820 ° C). Optionally, inductive heating within the finishing train between the finishing stands for the continuous rolling or semi-endless rolling operating mode to set higher final rolling temperatures (e.g. ≥850 ° C) and / or targeted influencing of the mechanical finished strip properties and / or at low casting speeds is being considered.

High forming in the finishing train (see definition above) with effective roll gap lubrication, preferably on all stands (optionally except for the last active finishing stand) that achieve a rolling force reduction of> 10% per stand due to lubrication, is also advantageous.

The transition from continuous rolling to batch rolling can be made by cutting on the first scissors S1 without a transition wedge. The first shear S1 cuts and the finish rolling of the endless slab takes place without changing the setup in the rolling stands R1 / R2 of the roughing train 5. By either reducing the casting speed and / or accelerating the continuous slab rolling, a gap is drawn that allows the rolling stand R1 and / or pierce the roll stand R2 with the new set-up for the subsequent slab.

List of reference symbols:

1

tape

2

Casting and rolling plant

3

Casting machine

4th

first oven

5

Roughing mill

6th

second oven

7th

Finishing mill

8th

Cooling section

9

Reel or reel system

S1

first scissors

S2

second pair of scissors

S3

third scissors

R1, R2

Roll stand of the roughing train

F1, F2

Roll stand of the finishing train

F3, F4

Roll stand of the finishing train

F5, F6

Roll stand of the finishing train

F.

Conveying direction

Claims (11)

1. Method of producing a metallic strip (1) in a casting and rolling plant (2), wherein the casting and rolling plant (2) comprises:

   - a casting machine (3) for casting a slab,

   - a first furnace (4) and/or a first roller path insulating section following the casting machine (3) in the conveying direction (F) of the metallic strip,

   - first shears (S1) arranged between the casting machine (3) and the first furnace (4) and/or the first roller path insulating section,

   - a roughing train (5) with a plurality of roll stands (R1, R2),

   - a second furnace (6) and/or a second roller path insulating section following the roughing train (5) in the conveying direction (F) of the metallic strip,

   - second shears (S2) arranged between the roughing train and the second furnace (6) and/or the second roller path insulating section,

   - a finishing train (7) with a plurality of roll stands (F1, F2, F3, F4, F5, F6),

   - a cooling path (8),

   - at least two coilers (9) or a reversing coiler and

   - third shears (S3) arranged between the cooling path (8) and the coiler installation (9),

   wherein one of the following operating modes is selected for production of the strip (1):

   a) endless rolling in which the casting machine (3), the roughing train (5) and the finishing train (7) are operatively connected with one another and rolling of the material is carried out with casting machine mass flow, wherein the finished strips are separated at the coiler installation (9) by means of the third shears (S3);

   b) endless rolling in the roughing train (5), in which the casting machine (3) and the roughing train (5) are operatively connected with one another and rolling of the material is carried out with casting machine mass flow, as well as individual strip rolling (batch operation) in the finishing train (7), wherein the pre-strips rolled in the roughing train (5) are separated by means of the second shears (S2) for individual strip rolling in the finishing train (7);

   c) individual strip rolling (batch operation) in the roughing train (5) and individual strip rolling (batch operation) in the finishing train (7), wherein the slabs produced in the casting machine (3) are separated by means of the first shears (S1) for individual strip rolling in the roughing train (5) and in the finishing train (7);

   d) semi-endless rolling in the roughing train (5) and/or semi-endless rolling in the finishing train (7), wherein the slabs produced in the casting machine (3) are separated by means of the first shears (S1) for semi-endless rolling in the roughing train (5) and/or wherein the pre-strips rolled in the roughing train (5) are separated by means of the second shears (S2) for semi-endless rolling in the finishing train (7), wherein the finished strips are separated at the coiler installation (9) by means of the third shears (S3),

   characterised in that
   rolling in the finishing train (7) is carried out with a plurality of roll stands, which takes place in accordance with the equation: $$2.316\times {\mathrm{h}}_{\mathrm{B}}\times {\mathrm{v}}_{\mathrm{B}}\times {\mathrm{e}}^{\left(-0.167\times \mathrm{n}\right)}\ge 480\mathrm{m}/\min \mathrm{mm}$$

   

   wherein

   n: number of stands in the finishing train (7)

   h_B: thickness of the slab in mm

   v_B: slab speed in m/min.
2. Method according to claim 1, characterised in that at least one slab is placed in the first furnace (4) or in the first roller path insulating section or an arrangement of first furnace parts (4) and roller path insulating sections in desired sequence and combination.
3. Method according to claim 1 or 2, characterised in that at least one slab or pre-strip is placed in the second furnace (6) or in the second roller path insulating section or an arrangement of second furnace paths (6) and roller path insulating sections in desired sequence and combination.
4. Method according to any one of claims 1 to 3, characterised in that the mean slab temperature at the outlet of the first furnace (4) is at least 1,000° C, preferably at least 1,100° C.
5. Method according to any one of claims 1 to 4, characterised in that the mean pre-strip temperature at the outlet of the second furnace (6) is at least 1,100° C, preferably at least 1,150° C.
6. Method according to any one of claims 1 to 5, characterised in that the degree of deformation of the strip (1) in the finishing train (7) is: $$\mathrm{\epsilon }=\left({\mathrm{h}}_{\mathrm{V}}-{\mathrm{h}}_{\mathrm{F}}\right)/{\mathrm{h}}_{\mathrm{V}}\times 100\ge 96\%$$

   

   with h_V as the pre-strip thickness and h_F as the finished strip thickness.
7. Method according to claim 6, characterised in that the mean pre-strip temperature at the outlet of the second furnace (6) is at least 1,150° C, wherein the product of the thickness of the strip (h_B) and speed of the strip (v_B) is at least 350 mm m/min, preferably at least 500 mm m/min.
8. Method according to any one of claims 1 to 7, characterised in that inductive heating of the slab and/or of the pre-strip is not undertaken.
9. Method according to any one of claims 1 to 8, characterised in that the temperature in the last active stand of the finishing train (7) lies above the γ-α phase conversion, in particular above 820° C.
10. Method according to any one of claims 1 to 7, characterised in that inductive heating is carried within the finishing train between the finishing stands for the operating mode of endless rolling or semi-endless rolling for the setting of higher final rolling temperatures ≥ 850° C and/or selective influencing of the mechanical finished strip properties and/or at low casting speeds.
11. Method according to any one of claims 1 to 10, characterised in that the length of the first furnace (4) or the first roller path insulating section or an arrangement of first furnace parts (4) and roller path insulating sections in any sequence and combination behind the first shears (S1) is preferably shorter than the length of the second furnace (6) or the second roller path insulating section or an arrangement of second furnace parts (6) and roller path insulating sections in any sequence and combination behind the second shears (S2).

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