EP3016762B1 - Cast-rolling installation and method for producing metallic rolled stock - Google Patents

Description

The invention relates to a casting and rolling system and a method for producing rolled metal from carbon steel.

Such casting plants and methods are basically known in the prior art; see e.g. B. the publications DE 196 81 466 , EP 1 112 128 , DE 693 16 703 , EP 1 833 623 and EP 1 940 566 .

Specifically, the European patent specification reveals EP 1 833 623 B1 a casting and rolling plant for the production of slabs with a mold, a strand guide downstream of the mold for deflecting the cast casting strand from the vertical to the horizontal, a heating furnace, a descaling device, a roughing stand, a Steckel rolling mill, a pair of scissors, a cooling device and a reel. After passing through the heating furnace, the casting strand or the slabs first go through the roughing stand before they enter the Steckel rolling mill. All of the system components mentioned lie in one line.

The European patent specification EP 1 940 566 B1 discloses a thin slab caster with a tandem roller. A thickness reduction for the casting strand is already provided in the strand guide; a so-called Liquid Core Reduction LCR area. The radius for deflecting the casting strand into the horizontal is less than 2 m, the casting thickness is 25 - 32 mm and the casting speed is 6 to 16 m / sec.

The German publication DE 196 81 466 T1 discloses a casting and rolling plant for the production of metallic rolling stock, comprising a casting line with a mold for the vertical casting of a casting strand and with a strand guide, which has a carpet for deflecting the casting strand from the vertical into the horizontal, a straightening device, a pair of scissors for distributing the casting strand in slabs and an outfeed roller conveyor. Parallel to the casting line, the casting and rolling system comprises a rolling line with an infeed roller table and a Steckel rolling mill for rolling the slabs of rolling stock, a cooling device downstream of the Steckel rolling mill and a winding device downstream of the cooling device. A transverse displacement device is arranged between the casting line and the rolling line for transversely transporting the slabs from the exit roller conveyor of the strand guide to the inlet roller conveyor of the rolling line. An oven is provided for heating the slabs during cross transport.

Such a casting and rolling line is also from the European patent application EP 2 399 683 A1 known.

The European patent application EP 0 625 383 A1 also discloses a casting and rolling line with a casting line and a rolling line. The casting line comprises a mold, a strand guide downstream of the mold for deflecting the casting strand from the vertical to the horizontal. The rolling line is offset parallel to the casting line. The casting line and the rolling line are coupled to one another via a transverse displacement device via a furnace with a transverse displacement device. In the outlet of the furnace there is a Steckel mill in the rolling line.

Finally, the European patent application discloses EP 2 441 538 a casting line with a strand guiding device, in which a so-called "soft reduction" section is formed for squeezing the casting strand in the area shortly before it solidifies.

The invention has for its object a casting and rolling system and a method for producing rolled metal according to the type described in the last paragraph to further develop in such a way that the heat losses when the slabs are transported from the casting line into the rolling line are further reduced.

This object is achieved by the casting and rolling plant claimed in claim 1.

The claimed design of the furnace has the advantage that the slabs are secured against undesired cooling not only during their transverse transport, but also on the outlet roller table of the strand guide and on the inlet roller table of the Steckel rolling mill, because the furnace also extends over these areas. By arranging the openings of the furnace for the entry of the slabs in the casting line and the analogous arrangement of the opening for the outlet of the slabs in the rolling line in the rolling direction, the widths of the openings or of the doors in these openings can be substantially the same as the width of the Slabs to be restricted. This is particularly advantageous with regard to the energy losses or the energy balance of the furnace in comparison with the construction of furnace doors in the prior art, where the furnace doors extend over the entire length of a slab because the slab is moved transversely into the furnace.

Both of the claimed measures thus serve to reduce the temperature losses of the slab and to increase the efficiency of the furnace.

The roller carpet of the strand guide is formed from a plurality of segments which are arranged one behind the other in the casting direction. In a first segment downstream of the mold, three to seven pairs of rollers are initially arranged vertically one above the other to form a vertical guide area for the casting strand. This vertical guide area is followed by five to eleven further pairs of rollers within the first segment in the casting direction, which are arranged in an arc shape to form a bending area for bending the casting strand from the vertical into a casting radius between 3.5 to 6.5 m. After the bending area, which is still assigned to the first segment, two to four further arc segments follow for further guiding the casting strand.

The claimed casting and rolling plant is used to produce rolled steel in the form of flat steel with an annual production of less than 700,000 tons of carbon steel per year. The system is characterized by a compact system layout and z. B. due to the lack of a roughing stand and the high efficiency of the furnace due to low investment and production costs. It is therefore particularly suitable for (new) steel producers in regions without previous flat steel production. It is used to cast slabs with widths between 700 and 1,700 mm.

According to a first exemplary embodiment of the invention, it is provided that the heating gas is conducted in the furnace in a flow direction which runs counter to the direction of movement of the slabs in the furnace. This countercurrent principle also leads to a significant increase in the efficiency of the furnace, because the slabs are better kept warm in this way.

According to a further preferred embodiment, the furnace has a further opening, which either serves as an outlet for slabs which are not to be introduced into the rolling line or functions as an inlet for slabs which are not to be supplied to the rolling line via the casting line. For this purpose, the run-out roller conveyor of the strand guide is extended beyond the transverse displacement area of the furnace through said further opening to outside the furnace in the casting line.

The above object is further achieved by a method for producing rolled metal material according to claim 13. The advantages of this solution correspond to the advantages mentioned above with reference to the claimed casting and rolling system.

The casting and rolling system is planned for casting speeds between 1 and 3.5 m / min.

After leaving the furnace, the slabs run directly into the rolling stand of the Steckel rolling mill, where they are reduced in thickness in a first pass and are subsequently downstream of the rolling stand on a Steckel located there, i.e. H. a winding furnace of the Steckel rolling mill located there. In order to increase production efficiency, the slab is not first wound up in a winding furnace located upstream of the roll stand of the Steckel rolling mill and temporarily stored before it enters the roll stand of the Steckel rolling mill.

Further advantageous refinements of the claimed casting and rolling system and the claimed method are the subject of the dependent claims.

Figur 1

die beanspruchte Gießwalzanlage in einem Längsschnitt;

Figur 2

den Ofen mit zugehörigem Einlaufrollgang und zugehörigem Auslaufrollgang in einer Draufsicht; und

Figur 3

die wesentlichen Komponenten der Gießlinie der beanspruchten Gießwalzanlage

zeigt.The invention is accompanied by three figures

Figure 1

the claimed casting and rolling plant in a longitudinal section;

Figure 2

the oven with associated infeed roller table and associated outfeed roller table in a plan view; and

Figure 3

the main components of the casting line of the claimed casting and rolling system

shows.

The invention is described in detail below with reference to the figures mentioned in the form of exemplary embodiments. In all figures, the same technical elements are denoted by the same reference symbols.

Explanation of terms used:

The term "rolling direction" corresponds to the term "casting direction"; both terms mean the same direction. However, the rolling direction is offset parallel to the casting direction.

The terms "Steckel" and "winding furnace" are synonymous.

The length of the furnace means the length in the casting or rolling direction. The width of the furnace means the extent of the furnace transverse to the casting or rolling direction.

The exit roller table of the strand guide is basically equivalent to the entry roller table of the furnace. Both run in the casting direction. An extension of the exit roller table of the strand guide, which extends through the furnace and outside the furnace, also extends in the casting direction.

The outlet roller table of the furnace extends in the rolling direction and is basically equivalent to the inlet roller table of the Steckel rolling mill.

Figure 1 shows the claimed casting and rolling plant in a side view. The casting and rolling system 100 comprises a casting line and a rolling line, which are connected to one another via a transverse displacement device 130. The casting line comprises a casting platform 105, a mold 110, a strand guide 120, a pair of scissors 127 and an outlet roller table of the strand guide 128. All the components of the casting line are arranged one behind the other in the casting direction in the order mentioned.

The casting platform typically includes a turret or ladle cart for handling the ladles for sequence casting. Concealed casting with ceramic components is provided between the pan and the distributor (shadow pipe) or between the distributor and the mold (dip pipe). The distributor is typically covered with covering powder and the mold with casting powder.

The mold 110 can either be formed from four parts, two broad sides and two narrow sides or as a frame mold. It preferably has an integrated level measurement which works, for example, radiometrically or with eddy current. Advantageously, the mold, especially if it has two narrow sides, has a narrow side adjustment for setting the format, preferably during the casting operation. The mold is positioned vertically below the casting platform. It can be designed with or without a funnel on the upper mold head. When designed as a funnel mold, the crowning is 10 to 60 mm at the upper mold head. The exit of the mold is preferably parallel, but in the case of a funnel mold it can also have a residual crowning of <10 mm. The mold walls or mold plates are preferably made of copper or a copper alloy with or without full or partial wear-reducing coating. The alternative to using a funnel mold is to use a plane-parallel mold. The mold is equipped with an eccentric or hydraulic oscillation drive for oscillation strokes up to 360 strokes per minute and amplitudes ≤ ± 5 mm. The mold is water-cooled with water volumes of 1,000 to 3,000 l / min / meter casting width.

The strand guide 120 essentially consists of a roller carpet with divided or undivided rollers with diameters <250 mm. The rollers can be designed as axle rollers or as journal rollers, preferably with internal cooling. Bearing cooling is primarily intended for central bearings.

The rolls of the roll carpet are preferably grouped into segments 121, 122, 123, 124, as shown in FIG Figure 2 is shown. The segments typically each consist of an upper frame and a lower frame, on each of which a plurality of rollers is rotatably mounted. The casting strand is, as in Figure 2 shown, performed between the opposite roles of a segment. The upper frame and the lower frame with the respective rollers rotatably mounted thereon are relative with the aid of hydraulic cylinders 129 adjustable to one another. This hydraulic segment adjustment is carried out as a black / white circuit on spacers or position-controlled with monitoring of the occurring forces with regard to a minimum and maximum permissible force value.

In a first segment 121, which immediately follows the mold 110 in the casting direction R, as in FIG Figure 2 shown, initially arranged three to seven pairs of rollers vertically one above the other. In this way, the vertical orientation of the casting strand predetermined by the mold is initially extended a little. Within the first segment 121, the said rolls are followed by a bending area which extends over 5 to 11 further pairs of rolls and continuously bends the casting strand into a casting radius between 3.5 and 6.5 m. In Figure 2 this bending area can be recognized by the horizontal lines that extend to the right from the pairs of rollers; these lines represent the change in the bending radius, which results successively on the individual roller pairs of the bending area. Said upstream connection of three to seven pairs of rollers in a vertical arrangement in front of the bending area has the advantage that forces occurring in the bending area are not transmitted into the mold 110, but are absorbed by the said roller pairs in a vertical arrangement.

The first segment 121 is followed by two to four further base segments 122, 123, 124 in the casting direction. The supported length of the casting machine is less than 12 m. No significant reduction in the thickness of the casting strand by means of Liquid Core Reduction LCR is provided within the strand guide. Changes in the thickness of the casting strand result only from the usual taper settings in parts or over the entire roller carpet in the casting direction, that is to say on the basis of the usual wedge settings of the segments in the casting direction to compensate for naturally occurring shrinkage of the casting strand in the casting direction due to its cooling. In addition, thickness reduction can only occur through the use of soft reduction. Softreduction means the active squeezing of the upper and lower strand shells in the area prior to solidification of the casting strand in order to, for. B. Avoid segregations.

Regulated secondary cooling is preferably provided within the strand guide 120, in the region of the segments, for cooling the strand after it has left the mold. The cooling is typically carried out via spray plans or preferably via a process model. In the transition area from the circular arc guide to the horizontal, the strand guide 120 has a straightening device 126, which consists of individually controllable and at least partially driven roller pairs. The controllable pairs of rollers preferably have position and force monitoring. The straightening device 126 can be designed as a three or four pair of rollers or alternatively in a segmented construction. The casting thickness of the casting strand at the exit of the straightening device 126 is between 90 mm and 120 mm. The overall height of the system is between 5 and 8 m.

As in Figure 1 shown, the strand guide 120 is followed by a pair of scissors 127 for dividing the casting strand into slabs of a predetermined length. The width of the slabs is between 700 and 1,700 mm for the stressed casting and rolling system.

An outfeed roller conveyor 128 is arranged downstream of the strand guide in the casting direction.

The slabs are transported from the casting line just described with the aid of a furnace 150, for example a lifting hearth furnace, into a rolling line which is offset parallel to the casting line. In this respect, the scissors 127 and the furnace 125 with a transverse displacement device 130 contained therein serve for the final coupling of the casting and rolling process.

The rolling line comprises an outlet roller table of the furnace 150, which is equivalent to an inlet roller table 140 in a Steckel rolling mill 160. A descaling device 158 is preferably arranged in the rolling line between the furnace 150 and the Steckel rolling mill 160. The Steckel rolling mill 160 comprises upstream and downstream a Steckel, ie a winding furnace for temporarily storing the rolling stock between the individual passes. A predetermined odd number of stitches are made to reduce the thickness of the slabs to a desired final thickness. The resulting rolling stock in the form of flat steel is cooled in a cooling device 170 after passing through the Steckel rolling mill 160 before it is either deposited as a plate or, as in FIG Figure 1 shown, is wound up into a bundle with the aid of a winding device 180.

The following will refer to Figure 3 the furnace according to the invention described in detail.

As in Figure 3 It can be seen that the furnace 150 according to the invention not only includes the actual area of the transverse sliding device 130, which serves to transversely transport the slabs from the casting line into the rolling line, but also the upstream run-out roller table 128 of the strand guide 120 and the downstream run-in roller table 140 of the rolling line into the Steckel rolling mill 160. That part of the run-out roller table 128 of the strand guide 120 which is covered by the furnace 150, also called the inlet region of the furnace, is heated and exposed to the furnace atmosphere, and the region of the transverse displacement device 130 (called the lifting hearth region). That from a heater, in Figure 3 Not shown, provided heating gas for the interior of the furnace is led into the interior of the furnace via an inlet in the elevator range. From there it flows against the direction of transport of the slabs to an outlet, which is preferably arranged at the beginning of the furnace inlet area transversely from the inlet for the slabs into the furnace, as shown in FIG Figure 3 is shown. In this way, a countercurrent principle is established between Slab run and heating gas, which is advantageous for the heat transfer to the slabs.

The length X2 of the transverse displacement device 130 in the casting direction, i.e. H. correspondingly the length of the part of the infeed roller table 140 for the Steckel rolling mill 160 enclosed by the furnace is between 15 and 35 m corresponding to the maximum length of the slabs. The length of the entry zone into the oven, i.e. H. that part of the run-out roller table 128 of the strand guide 120 enclosed by the furnace is in relation to the length X2, the ratio X1 / X2 being <1.5, preferably approximately 1. The width Y1 of the furnace 150 transverse to the casting direction is also in relation to the length X2 of the furnace 150. The ratio Y1 to X2 is preferably 0.2 to 0.8, preferably approximately 0.5.

The information given for the length X2 and the ratios X1 to X2 and Y1 to X2 are selected so that a roll change can be carried out without interrupting the casting sequence.

According to the invention, the furnace 150 is constructed such that, as in FIG Figure 3 shown, the slab in the casting direction can run into the front of the furnace from the front via the outlet roller conveyor 128 with its narrow side first. The slabs are also brought out at the end, ie with their narrow side first backwards via the roller table 140 in the direction of the Steckel rolling mill. The exit roller table 128 of the strand guide 120 can be extended through the furnace 150 and beyond in the form of an outlet / insertion roller table 190 for the slabs, as shown in FIG Figure 3 is shown. In this case, a further door must be provided in the furnace wall in the transition to said extension / withdrawal roller table 190. Due to the fact that the slabs enter the furnace on the front and not on the transverse side, all of the furnace doors at the outlets and inlets for the slabs can essentially be adjusted to the max. Slab width can be limited. In particular, no doors or openings have to be provided in the furnace which allow the slabs to be introduced and carried out transversely to the casting line.

In this way, the temperature and energy losses of the furnace can be significantly reduced.

All roller conveyors in the furnace 150 can be designed with rollers mounted on one or two sides, with or without roller cooling.

Reference symbol list

100

Casting mill

105

Casting platform

110

Mold

120

Strand guide

121

first segment

122

second segment

123

third segment

124

fourth segment

125

Roller carpet

126

Straightening device

127

scissors

128

Exit roller table of the strand guide

129

Hydraulic cylinder

130

Cross slide device

140

Infeed roller table in the Steckel mill in the rolling line

150

oven

156

Opening in the oven

158

Descaling device

160

Steckel rolling mill

162

Winding furnace

164

Winding furnace

170

Cooling device

180

Take-up device

190

Extension / insertion roller table for slabs

210

Casting strand

R

Pouring direction

X1

Length of the furnace in the casting direction

X2

Length of the transverse displacement area in the casting direction

Y1

Width of the cross-shift area

Claims (18)

1. Casting-and-rolling plant (100) for producing metallic rolled material, comprising:

   a casting line with a mould (110) for vertical casting of a cast strip (210) and with a strip guide (120), which comprises a roller carpet (125) for deflecting the cast strip from the vertical into the horizontal, a straightening device (126), shears (127) for dividing the cast strip into slabs and an outlet roller path (128),

   a rolling line, which is arranged parallel and offset with respect to the casting line, with an inlet roller path (140) and with a Steckel rolling mill (160) for rolling the slabs to form the rolled material;

   a transverse displacing device (130) for transverse transport of the slabs from the outlet roller path (128) of the strip guide to the inlet roller path (140) of the rolling line; and

   a furnace (150) for heating the slabs during the transverse transport, wherein the furnace (150) encloses the complete transverse displacing device (130), at least a part of the outlet roller path (128) of the strip guide and at least a part of the inlet roller path (140) of the rolling line and wherein the inlet of the furnace for the slabs is arranged in the casting line and the outlet of the furnace for the slabs is arranged in the rolling line,

   characterised in that

   the roller carpet (125) of the strip guide is formed from a plurality of segments arranged in succession in casting direction (R); wherein in a first segment (121) directly following the mould (110) initially three to seven roller pairs are arranged vertically one above the other for forming a vertical guide region for the cast strip and subsequently a further five to eleven roller pairs are arranged in curved format within the first segment for forming a bending region for bending the cast strip from the vertical at a casting radius of between 3.5 to 6.5 metres; and wherein two to four curved segments (122, 123, 124) for guidance of the cast strip at the casting radius between 3.5 and 6.5 metres are arranged downstream of the first segment; and

   the thickness of the cast strip (120) at the end of the strip guide is between 90 millimetres and 120 millimetres.
2. Casting-and-rolling plant (100) according to claim 1, characterised in that the furnace (150) comprises a heating device for providing hot gas for the interior of the furnace, an inlet for the feed of the hot gas into the interior of the furnace against the transport direction of the slab, wherein the inlet is preferably arranged at an end of a transverse displacement region of the furnace, and an outlet for discharge of the hot gas from the furnace, wherein the outlet is preferably arranged at the start of the outlet roller path of the strip guide to one side of the inlet for the slabs into the furnace.
3. Casting-and-rolling plant (100) according to one of the preceding claims, characterised in that the length (X2) of the part, which is surrounded by the furnace, of the inlet roller path (140) for the Steckel rolling mill is between 15 metres and 35 metres.
4. Casting-and-rolling plant (100) according to claim 3, characterised in that the ratio of the length (X1) of the part, which is surrounded by the furnace, of the outlet roller path of the strip guide to the length (X2) of the transverse displacement region is less than 1.5, preferably approximately 1.
5. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised in that the ratio of width (Y1) of the furnace to the length of the transverse displacement region (X2) lies between 0.2 and 0.8, preferably at approximately 0.5.
6. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised in that the furnace (150) has a further opening (156), which either serves as an outlet for slabs which are not to be introduced into the rolling line or functions as an inlet for slabs which are not to be fed by way of the casting line to the rolling line, and the outlet roller path (1128) of the strip guide is extended in the casting line beyond the transverse displacement region out through the further opening (156) to outside the furnace.
7. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised in that the furnace (150) is formed as walking open-hearth furnace.
8. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised in that the wide side walls of the mould (110) are formed to extend parallelly at the outlet of the mould.
9. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised in that the strip guide (120) has a soft reduction region ahead of the region of hardening-through of the cast strip.
10. Casting-and-rolling plant (100) according to any one of the preceding claims, characterised by a cooling device (170), which is downstream of the Steckel rolling mill (160) in casting direction (R), for cooling the rolled material and, for example, a coiling device (180), which is downstream of the cooling device in casting direction, for coiling the cooled rolled material.
11. Casting-and-rolling plant according to any one of the preceding claims, characterised in that the supported length of the casting-and-rolling plant as measured from the casting meniscus to the start of the outlet of the strip guide is less than or equal to 12 metres.
12. Casting-and-rolling plant according to any one of the preceding claims, characterised in that the constructional height of the casting-and-rolling plant is between 5 and 8 metres.
13. Method of producing metallic rolled material, comprising the following steps:
    in a casting line:

    vertical casting of a cast strip (210);

    deflecting the cast strip from the vertical into the horizontal; and

    dividing the cast strip into slabs;

    transversely transporting the slabs from the casting line to a rolling line arranged to be parallelly offset, wherein the slabs are heated or at least kept warm in a furnace; and

    in the rolling line:

    rolling and reducing the thickness of the slabs in a Steckel rolling mill to form rolled material;

    characterised in that

    the deflection of the casting strip from the vertical into the horizontal takes place in a strip guide (12) with a roller carpet (125), wherein

    the roller carpet (125) of the strip guide is formed from a plurality of segments arranged in succession in casting direction (R); wherein in a first segment (121) directly following the mould (110) initially three to seven roller pairs are arranged vertically one above the other for forming a vertical guide region for the cast strip and subsequently a further five to eleven roller pairs are arranged in curved format within the first segment for forming a bending region for bending the cast strip from the vertical at a casting radius of between 3.5 to 6.5 metres; and wherein two to four curved segments (122, 123, 124) for guidance of the cast strip at the casting radius between 3.5 and 6.5 metres are arranged downstream of the first segment and wherein the thickness of the casting strip (210) at the end of the strip guide lies between 90 millimetres and 120 millimetres;

    the rolling and thickness reduction of the slabs to form rolled material is carried out in a Steckel rolling mill; and

    the slabs at the end in casting direction enter the furnace and rearwardly at the end in rolling direction exit the furnace.
14. Method according to claim 13, characterised in that the casting speed is between 1 and 3.5 metres per minute.
15. Method according to claim 13 or 14, characterised in that the slabs in the interior of the furnace (150) directly after entry thereof into the furnace, during their transverse transport and preferably also during their subsequent transport in rolling direction are acted on by a hot gas which flows against the respective transport direction of the slabs.
16. Method according to any one of claims 13 to 15, characterised in that the slabs after leaving the furnace directly enter the roll stand of the Steckel rolling mill, are reduced in thickness there in a first pass and subsequently are wound up on the Steckel, which is downstream of the roll stand, of the Steckel rolling mill.
17. Method according to claim 16, characterised in that the slabs are rolled in the Steckel rolling mill to their predetermined final thickness by at least three passes before they are cooled as rolled material in the form of flat steel and, for example, coiled.
18. Method according to any one of claims 13 to 17, characterised in that the material from which the cast strip, slabs and rolled material are produced is carbon steel.

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