KR20030071890A - Installation for producing a hot-rolled strip - Google Patents

Abstract

The present invention relates to an apparatus for producing hot roll strips from a melt in accordance with two roll casting methods. It is an object of the present invention to increase the melt throughput in a tundish and substantially reduce the casting time of a batch, beyond the performance of a single strand casting apparatus operating according to two roll casting methods with minimal investment and operating costs. To this end, the present invention provides a casting ladle 1 having a molten outlet 5 is provided with a tundish 6 for receiving molten metal from the casting ladle. One tundish 6 has at least two bottom outlets 8 which transfer the melt to two twin-roll casting apparatuses 10a and 10b. Each casting nip 13 is provided with one or more bottom outlets 8a, 8b of the tundish 6. The two casting nips 13a, 13b are arranged 15 ° to 180 ° with respect to the longitudinal axis and offset parallel to each other.

Description

Facility for manufacturing hot rolled strips {INSTALLATION FOR PRODUCING A HOT-ROLLED STRIP}

In accordance with the twin-roll casting process, this type of plant for producing thin, near-net hot strips, preferably steel strips, is placed in a horizontal plane with two driven opposed rotating casting rolls arranged at a distance from each other. It includes a rotational axis. The rolls form a casting nip and the lateral boundary of the casting nip is formed by the side plate pressed into the casting roll at the end side. Side plates that can be pressed vertically on the casting roll side surface are also known for this purpose. Two casting rolls and side plates form a molten space through which the molten metal is introduced through the impregnated casting nozzle. At the two cooled side surfaces of the casting rolls, the melt forms a strand shell that solidifies and joins to form a casting strip in the narrowest gap between the casting rolls. The metal strip, which is discharged vertically downward and then converted to the horizontal plane, is subjected to further processing in the downstream processing apparatus and wound up with a metal coil.

Plants using the twin-roll casting process described above are already known from AT-B 406 938. Twin-roll casting plants arranged in parallel to each other are supplied with molten metal independently, and each twin-roll casting plant is assigned a separate ladle turntable and a separate tundish. The produced metal strip is wound into coils and the coils from the two casting plants are conveyed to additional rolling plants, where the coils are further processed. This plant configuration doubles the manufacturing capacity.

In the vertical twin-roll casting process, the strip casting speed is limited to 15 to 150 m / min for 1.5 to 5 mm strip thickness by heat dissipation, limited to time and short passage distance on the casting roll surface. Thus, the production capacity achievable in this type of plant is limited between about 0.5 and 1.5 t / min and with meter strip width. This corresponds to a maximum manufacturing capacity of 100 t / h for a stantard one-stranded plant for casting widths up to 1300 mm.

In the case of casting ladles with a capacity of at least 150 tons of molten metal, as is often used, this requires more than two hours of casting time and therefore undesirably alters casting conditions during casting time.

In some continuous casting plants, casting per casting ladle using multi-strand casting fixtures, especially in casting plants for producing small metal strands, such as billet continuous casting plants and boom casting plants. Minimizing time is quite normal. In this case, the permanent mold and the downstream strand-guided means are arranged very close together. The molten metal is supplied to a separate permanent mold by a common casting ladle and passes through a plurality of casting openings via a common tundish. Plants of this type are already known from DE-A 19 08 648 where a large number of billet strands with very small cross sections can be produced by a tubular mold arranged in a semicircular shape. According to this configuration of the permanent mold, the individual cast strands are removed at equal angular intervals in the beam shape. In this small cross section, the problem of arranging two permanent molds into strip cross sections and high length / width ratios in a limited tundish size to cast the strands does not arise.

There are several known examples of two strand strip casting plants (EP-B 347 662, JP-A 62-187505), whose permanent molds are supplied to the melt by tundish. However, these permanent molds do not work according to the vertical twin-roll casting process, but are equipped with track molds or conventional plate molds and may suitably have a central wide area for impregnated casting nozzles. In view of the side roll bearings, the side plates that can be placed on the end side of the casting rolls together with the hydraulic actuation mechanism and the drive for the casting rolls, the twin-roll casting plant required for the twin-roll casting process is more axial than the permanent molds of other designs. This requires a lot more space. Given these design conditions and the desired high production width, the casting rolls cannot be brought together close together in the axial direction such that a common tundish for a twin-roll casting plant can be arranged on the roll in a conventional manner. There are imposed restrictions on the dimensions of the tundish, taking into account the need for uniform heating and desired melt guidance and adjustment in the tundish prior to starting operation. A tundish with a length of 10 m or more results in a very high metal content and a very large wet refractory lining surface area compared to the total output of the two twin-roll casting units, thus increasing the consumption of refractory material and reducing the production rate, Almost technically invisible.

The present invention relates to a plant for producing hot strips from metal melt according to a twin-roll casting process using two twin-roll casting devices.

1 is a longitudinal sectional view of a plant performing two roll casting processes according to the prior art,

2a is a plan view of a plant according to the invention with two product lines arranged at an angle of 90 °,

2b is a diagram defining angles a and beta in a device according to the invention,

3a is a plan view of a plant according to the invention with two product lines arranged at an angle of 180 °,

FIG. 3B schematically shows a plan view of a variant of the apparatus shown in FIG. 3A.

Therefore, it is an object of the present invention to significantly increase melt productivity in tundish beyond the capacity limitations of one-stand casting, operating along the twin-roll casting process, avoiding these defects and difficulties and following the twin-roll casting process. It is possible to provide a casting plant which can simultaneously and greatly reduce batch casting times. Another object of the invention is to ensure that the state for the metal melt melts without further heating, in particular with respect to the invariability of the casting temperature over the casting time, and the size of the tundish, in particular the distance between the bottom outlets To keep it small. It is yet another object of the present invention to obtain a plant configuration in which the maximum number of plant parts is used with multiple product lines.

According to the invention, this object is assigned to a casting ladle with a melt outlet for the tundish for receiving the molten metal from the casting ladle, in which one twin dish two twin-roll casting devices (twin) This is achieved through the fact that there are at least two bottom outlets for transferring the melt to the -roll casting device. In addition, each casting nip is assigned to one or more of the bottom outlets of the tundish, and the two casting nips are 15 ° to 180 °, preferably 45 ° to 120 ° with respect to each other with respect to the longitudinal range. , In particular at an angle α of 60 ° to 120 °. It is an advantageous arrangement if the two casting nips are arranged at an angle α of approximately 90 ° with respect to each other with respect to the longitudinal range.

Each twin-roll casting device forms a product line downstream of which the strip processing apparatus is arranged, and the product lines to which metal melts are supplied from a common tundish are 15 ° to 180 °, preferably 45 ° to each other. When arranged at an angle α of 120 °, in particular 60 ° to 120 °, an advantageous plant design is achieved. The angular position of the two product lines with respect to each other allows these product lines to be closer together in the area of the actual twin-roll casting device, and minimizes the distance between the central feed positions for the metal melt, thereby reducing the Shorten the length. It is a preferred plant arrangement if the product lines to which the metal melt is fed by a common tundish are arranged at an angle β of approximately 90 ° with respect to each other.

Strip-switching devices in product lines if the angle α forming the position of the casting nips of the two twin-roll casting apparatuses with respect to each other is the same as the angle β forming the position of the two product lines with respect to each other This avoids the need to arrange strip-diverting devices.

If the common service area for at least one, preferably two, subsequent applications is arranged in a smaller angular area between two adjacent twin-roll casting devices and strip processing devices arranged downstream thereof, according to the invention Another advantage of arrays is:

Cast-rolling shops,

Casting roll changeover station,

Roll change station

Roll grinding mills,

Plant operating stand,

Product logistics

Cost savings during operation and during maintenance and synergies from reduced investment costs also occur in the case of other plant components. In some areas, redundant facilities in logistic sectors and maintenance are avoided, plant monitoring is simplified, and the work required to be performed by the operating staff is facilitated.

If the two casting nips are arranged offset and parallel to each other with respect to their longitudinal range, the length of the tundish is likewise compared to the arrangement of two twin-roll casting apparatuses positioned next to each other with the casting nips. There is an arrangement of two twin-roll casting apparatuses which reduce or minimize. It is preferable that the product lines to which the molten metal is supplied by the common tundish are arranged to be led away from each other.

The arrangement of the casting nip and / or product line according to the invention, in particular having an angular position of the product line with respect to each other of 45 ° to 120 °, provided that at least one roll stand is arranged downstream of each twin-roll casting device It has proved to be particularly advantageous. On the drive side, the rolling stand needs space for the drive unit of the roll and on the actuation side it needs space for the roll change device. The preferred angular position of the product line relative to each other allows the roll grinding mill to be arranged in the spatially enclosed area of the production hall between the roll replacement station, the associated bearing arrangement and, if appropriate, the two roll stands. do.

If the casting ladles are supported in the bearing device, these bearing devices are formed by the ladles, which are rotatable with two or more receivers for the casting ladles and capable of rotating about a vertical axis, in the casting position, An effective casting ladle arrangement is achieved if the melt exit from the casting ladle is arranged approximately centered over the tundish, preferably in the region of the projecting limb of the T-shaped tundish. The tundish may be trough-like and in this way can be believed to be equivalent to a T-shaped tundish.

The melt does not interfere with strand cell formation on the casting roll surface if the bottom exit in the tundish comprises an impregnating casting nozzle that projects into the center of the free melt receiving space between the two interactive casting rolls of the twin-roll casting equipment. Transfer from tundish to twin-roll casting plant.

For the reasons already mentioned, the bottom exits in the tundish are spaced 8.5 m apart.

The invention is described in more detail below on the basis of a plurality of exemplary embodiments schematically illustrated in the drawings.

As is conventionally used according to the prior art, a longitudinal cross-sectional view of a complete plant for producing steel strips from a steel melt using the twin-roll casting process already described in the introduction is shown schematically in FIG. Only the most important components of the plant are shown. The casting ladle 1 filled with the steel melt is transferred from the melting workshop to the casting plant using a physical metallurgical conveyor or a hole crane (not shown) and then rotated about a vertical axis 3. It is inserted into the receiver 2 of 4). From the casting ladle 1 moved to the casting position, the steel melt flows through the melt outlet 5 to the tundish 6 and from the tundish 6 the bottom outlet 8 formed by the impregnated casting nozzle 7. Flow through the twin-roll casting apparatus (10). The twin-roll casting device 10 is formed by two casting rolls 11, 12 that are supported, driven and opposed to rotate in a bearing in a bearing frame (not shown). With the side plates arranged at the end faces (not shown in FIG. 1), the casting rolls 11, 12 arranged at an adjustable distance to each other allow for casting nip 13 and a molten metal in a limited longitudinal range. A strand cell is formed here, which forms a space 14 and solidifies at the casting roll surface, which is pressed into the casting nip 13 by rotation of the casting rolls 11, 12, thereby casting the cast metal strip 15. ). The metal strip 15 is then discharged from the casting nip 13 and converted to a horizontal plane, which is conveyed to the rolling stand 18 by a pair of pinch rolls 16, 17, where the metal strip 15 is in tension. maintain. As the manufacturing process continues, the metal strip 15 is cooled as it passes through the cooling device 19, divided transversely according to the coil weight required by the scissors 20 and wound around the coil in the coiler 21. All. Other devices such as looping pit to compensate for different speeds between each manufacturing device, trimming scissors to handle the edges of the metal strip, evacuation chamber to prevent the formation of scale on the metal strip, etc. Are generally integrated into such plants.

An embodiment of an apparatus having two product lines 23, 24 is shown in FIG. 2A, where each of the two product lines 23, 24 performs a vertical twin-roll casting process 10a of the type described above. , 10b). The two product lines 23, 24 are arranged at an angle β, ie 90 ° with respect to each other. The casting nips 13a, 13b of the twin-roll casting apparatus 10a, 10b having the casting rolls 11a, 12a and 11b, 12b are arranged so as to be offset by an angle α, that is, 90 ° with respect to each other, and two twins The roll casting devices 10a, 10b extend obliquely and are covered by a tundish 6 to which molten metal is supplied. To this end, the bottom outlets 8a and 8b are precisely positioned on the casting nips 13a and 13b of the twin-roll casting apparatuses 10a and 10b, respectively, to provide a symmetrical inflow of the melt into the molten metal receiving space 14 (FIG. 1). To ensure. A ladle turntable 4 is used to move the casting ladle 1 to a casting position on the tundish 6, where the metal melt is brought into the projecting limb 25 of the T-shaped tundish 6. Flow.

Similar stream processing devices are arranged in two product lines 23, 24, each of which only has a rolling stand 18a, 18b and nose that reduce the thickness of the metal strip, improve microstructure, and smooth the surface. Only the curlers 21a, 21b are shown schematically in FIG. 2A. In addition to the rolling stands 18a and 18b, the area for the roll replacement stations 30a and 30b and, if appropriate, the common bearing of the roll set and the additional area for the roll grinding mill (not described in more detail) are two adjacent product lines 23 and 24. Is provided in the hole area between. The same strip processing devices are arranged closely together and the possibility of combining these devices results in a preferred operating state for operation and maintenance staff with short transfer paths and conventional logistics. For example, for casting roll replacement stations and casting roll workshops, plant control stands and product warehouses, a synergistic effect is produced.

In figure 2b the casting nips 13a, 13b of the two casting roll devices are shown at an angle α of 60 °. The angle β between the two product lines 23, 24 is also 60 ° so that the casting nips 13a, 13b are always positioned perpendicular to the orientation of the product lines 23, 24. Different angle positions α and β are possible, but strip switching devices are required which are arranged at the beginning of the product lines 23, 24.

FIG. 3a shows another possible embodiment of the arrangement of two product lines 23, 24 in which in each case one twin roll casting device 10a, 10b is combined to carry out a twin roll casting process. 23 and 24 are arranged at an angle of 180 degrees, ie parallel, and offset with respect to each other. In this case, the ladle turntable 4 and the tundish 6, in which the two product lines 23, 24 start oriented in opposite directions, are located in the center of the plant in this case, so that the casting strip is in the opposite direction. Pass through the line.

FIG. 3b shows a variant of the plant arrangement shown in FIG. 3a, in which the product lines 23, 24 and thus also the casting nips 13a, 13b and the casting roll device are laterally offset parallel to one another. Is placed.

The invention is not limited to the described embodiments. Individual plant parts can be used in various modified forms. It is within the scope of protection of the present invention to provide other floor mounted bearing arrangements for casting ladles, such as for example displacement ladle carriages instead of ladle turntables. Casting cranes with hanging casting ladles are also used to replace ladle turntables. Depending on the angular position of the product lines relative to each other, it is possible to modify the shape of the tundish, so that the tundish may be designed as a substantially rectangular trough member or V-shaped tundish. A variation on the shape of the tundish of this characteristic is also protected by the scope of protection of the T-shaped tundish. Multiple stand rolling devices can also be used in separate product lines to achieve higher reduction rates.

Claims (12)

Twin-roll casting process using two twin-roll casting apparatuses 10a, 10b formed by two casting rolls 11a, 12a; 11b, 12b respectively forming casting nips 13a, 13b, respectively. In a plant for producing hot strips from a melt according to A casting ladle 1 having a molten outlet 5 is provided with a tundish 6 for receiving molten metal from the casting ladle, wherein one tundish 6 draws the molten metal into two twin-roll casting devices. Two or more bottom outlets (8) for conveying to (10), each of the casting nips (13) being provided with one or more bottom outlets (8a, 8b) of the tundish (6); The casting nips 13a, 13b are characterized in that they are arranged at an angle α of 15 ° to 180 °, preferably 45 ° to 120 °, in particular 60 ° to 120 °, with respect to the longitudinal axis of each other, Plant for manufacturing hot strips. The method of claim 1, The two casting nips 13a and 13b have an angle of approximately 90 ° with respect to the longitudinal axis of each other. characterized in that arranged in (α), Plant for manufacturing hot strips. The method according to claim 1 or 2, Product lines 23 and 24 fed from a common tundish 6 are arranged at an angle β of 15 ° to 180 °, preferably 45 ° to 120 °, in particular 60 ° to 120 ° with respect to each other. Characterized in that Plant for manufacturing hot strips. The method of claim 3, wherein It is characterized in that the product lines 23 and 24 which are supplied with molten metal from the common tundish 6 are arranged at an angle of approximately 90 ° with respect to each other, Plant for manufacturing hot strips. The method according to claim 3 or 4, The angle α defining the position of the casting nips 13a and 13b with respect to each other is equal to the angle β defining the position of the product lines 23 and 24 with respect to each other, Plant for manufacturing hot strips. The method according to any one of claims 1 to 5, Two adjacent twin-roll castings have a common service area for one or more, preferably two or more, applications such as casting roll shops, casting roll change stations, roll change stations, roll grinding mills, plant operating stands, product warehouses Characterized in that it is arranged in said angled area between the devices 10a, 10b and the strip processing apparatus (product line) arranged downstream, Plant for manufacturing hot strips. Twin-roll casting process using two twin-roll casting apparatuses 10a, 10b formed by two casting rolls 11a, 12a; 11b, 12b respectively forming casting nips 13a, 13b, respectively. In a plant for producing hot strips from a melt according to A casting ladle 1 having a molten outlet 5 is provided with a tundish 6 for receiving molten metal from the casting ladle, wherein one tundish 6 draws the molten metal into two twin-roll casting devices. Two or more bottom outlets 8a, 8b for feeding to 10a, 10b, each of the casting nips 13a, 13b having one or more bottom outlets 8a, 8b of the tundish 6; It is provided, characterized in that the two casting nips (13a, 13b) are arranged parallel to each other in the longitudinal axis and in the form of an offset, Plant for manufacturing hot strips. The method of claim 7, wherein Characterized in that the product lines (23, 24) receiving molten metal from a common tundish are arranged spaced apart from each other, Plant for manufacturing hot strips. The method according to any one of claims 1 to 8, Characterized in that one or more rolling stands 18a, 18b are arranged downstream of each twin-roll casting device 10a, 10b, Plant for manufacturing hot strips. The method according to any one of claims 1 to 9, The casting ladle is supported in a bearing device, the bearing device being formed by a ladle turntable 4 having two or more receivers 2 for the casting ladle and capable of rotating about a vertical axis and in the casting position. Characterized in that the molten outlet of the casting ladle is arranged at approximately the center above the tundish 6, preferably at the center inside the region of the protruding rim 25 of the T-shaped tundish 6, Plant for manufacturing hot strips. The method according to any one of claims 1 to 10, Bottom outlets 8a, 8b of the tundish 6 are free molten metal receiving spaces between the two interactive casting rolls 11a, 12a, 11b, 12b of the twin-roll casting apparatus 10a, 10b. It characterized in that it comprises an immersion type casting nozzle (6) protruding to the center of 14), Plant for manufacturing hot strips. The method according to any one of claims 1 to 11, The bottom outlets 8a, 8b of the tundish 6 are characterized in that they are spaced apart from each other by 8.5 m or less, Plant for manufacturing hot strips.