EP4214006A1

EP4214006A1 - Continuous casting machine and method for operating the continuous casting machine

Info

Publication number: EP4214006A1
Application number: EP21773306.2A
Authority: EP
Inventors: Franz Wimmer; Jeffrey Morton; Alfred Trauner
Original assignee: Primetals Technologies Austria GmbH
Current assignee: Primetals Technologies Austria GmbH
Priority date: 2020-09-18
Filing date: 2021-09-01
Publication date: 2023-07-26
Also published as: AT524482A1; WO2022058168A1; AT524482B1

Abstract

The invention relates to a continuous casting machine (10) for alternately casting a first hot strand (70) with a rectangular cross-section and a second hot strand (260) with a circular cross-section from a metal melt (65) and a method for operating the continuous casting machine (10), wherein the continuous casting machine has a strand guide (55) with at least one first driving stand (80) and a second driving stand (85) arranged downstream in the feeding direction (75) of the first hot strand (70), wherein the first driving stand (80) has a first roll pair (105) with a first roll (110) and a second roll (115) and the second driving stand (85) has a second roll pair (141) with a third roll (145) and a fourth roll (150), wherein the first roll (110) and the second roll (115) each have, on the circumferential side, a first running surface (195), which is in each case designed cylindrically in a first partial section (200), wherein the first roll (110) and the second roll (115) each have, in a second partial section (205) of the first running surface (195) adjacent to the first partial section, a first recess (215) formed circumferentially on the first running surface (195), wherein the third roll (145) and the fourth roll (150) each have a cylindrical second running surface (220), wherein the first partial section (200) is designed to guide the first hot strand (70) and the first recess (215) is designed to guide the second hot strand (260).

Description

description

Continuous casting plant and method for operating the continuous casting plant

The invention relates to a continuous casting plant according to patent claim 1 and a method for operating such a continuous casting plant according to patent claim 10 .

EP 3 135 402 A1 discloses a continuous casting installation for producing a rectangular hot strand.

It is the object of the invention to provide an improved continuous casting installation and an improved method for operating the continuous casting installation.

This object is achieved by means of a continuous casting plant according to patent claim 1 and a method for operating the continuous casting plant according to patent claim 10 . Advantageous embodiments are specified in the dependent claims.

It was recognized that an improved continuous casting plant for alternately casting a first hot strand with a rectangular and a second hot strand with an elliptical or circular cross section from a metallic melt can be provided by the continuous casting plant having a strand guide with at least one first driver stand and a second driver stand offset in the conveying direction of the first hot strand. The first driver frame has a first pair of rollers with a first roller and a second roller, and the second driver frame has a second pair of rollers with a third roller and a fourth roller. The first hot strand or the second hot strand can be guided through between the first pair of rollers and the second pair of rollers. The rollers are each rotatably mounted. The first roller and the second roller each have a first running surface on the circumference, each of which is cylindrical in a first section. The third roller and the fourth roller each have a cylindrical second running surface. The third and fourth The roller and the first section of the first roller and the second roller are each designed to guide the first hot strand with the rectangular profile. In a second section of the first running surface adjoining the first section in a direction inclined to the conveying direction, the first roller and the second roller each have a first indentation formed circumferentially on the first running surface. The first indentation of the first roller and the second roller are each designed to guide the second hot strand.

This configuration has the advantage that both the first hot strand with a rectangular cross-section and the second hot strand with a round cross-section can be produced by means of the continuous casting plant simply by changing the mold with an identical strand guide, without the strand guidance is to be adapted. Furthermore, it is ensured that the second hot strand has a particularly round profile on an outer peripheral side and flattening of the second hot strand is avoided.

As a result, high-precision pipe material can be produced particularly well from the second hot strand.

In a further embodiment, the first roller and/or the second roller has a third section, the third section adjoining the direction of the second section on a side of the second section remote from the first section. In the third section, the first roller and/or the second roller is configured in a cylindrical manner. This configuration has the advantage that with the third section, the first and/or second roller can guide the first hot strand on both sides, so that tilting of the first hot strand between the first roller and the second roller can be reliably avoided.

In a further embodiment, the first section has a first outside diameter and the third section has a further outside diameter which is essentially identical to the first outside diameter. This configuration has the advantage that the rectangular profile of the first hot strand is maintained and in particular no steps are rolled into the first hot strand.

In a further embodiment, the continuous casting plant can be operated in a first operating state and a second operating state. In the first operating state, a first mold with a rectangular mold cross-section is used in the continuous casting installation, and in the second operating state a second mold with a circular or elliptical mold cross-section is used. In the first operating state, the first mold is designed to cast the first hot strand with the rectangular cross section from the metallic melt and in the second operating state to cast the second hot strand with the circular or elliptical cross section from the metallic melt. This configuration has the advantage that the continuous casting plant is able to cast hot strands of different cross-sectional shapes solely by changing between the first mold and the second mold, without further conversions being necessary. As a result, the set-up times for producing the first hot strand with a rectangular cross section or for producing the second hot strand with a circular or elliptical cross section are particularly short. This ensures high capacity utilization of the continuous caster.

In a further embodiment, the first driver stand has a first measuring device, the first measuring device being designed to determine a first distance between the first roller and the second roller. This configuration has the advantage that, by determining the distance, a thickness of the first hot strand can be determined before the first hot strand is introduced to the driver stand. In particular, when carrying out a soft reduction of the first hot strand on the second driver stand, the second driver stand can be controlled particularly precisely on the basis of the first distance determined.

In a further embodiment, the continuous casting plant has at least one third driver stand, the third driver stand having a third pair of rollers, each with a rotatably mounted roller fifth role and a sixth role. The third driver stand is arranged downstream of the second driver stand in relation to the conveying direction of the first hot strand. The second driver framework is subordinate to the first driver framework. The fifth roller and the sixth roller each have a third running surface on the circumference, each of which is designed in a cylindrical manner in a fourth section. In each case in a fifth section of the third running surface, which adjoins the fourth section in the direction, a second indentation is formed circumferentially on the third running surface. The fourth section of the fifth roller and the sixth roller are each designed to rest against the first hot bar on both sides, with the second indentation of the fifth and sixth roller each being designed to guide the second hot bar. This design has the advantage that the rectangular first hot strand and the second hot strand can be guided with the third driver stand. As a result, both the first and the second hot strand can be supported particularly well over the entire length of the strand guide, so that buckling of the first or the second hot strand while passing through the strand guide is avoided.

In a further embodiment, the third driver stand has a second measuring device, the second measuring device being designed to determine a third distance between the fifth roller and the sixth roller. This configuration has the advantage that when the first hot strand is being produced, the second distance between the second pair of rollers can be regulated on the basis of the first distance and the third distance, for example in closed-loop control.

In a further embodiment, the first indentation is concave and has a curvature. The first indentation is configured to form an outer peripheral side of the second hot bar with an outward curvature. The curvature is preferably larger than the outer curvature. Preferably, the curvature is greater than the outer curvature by at least a factor of 1.2 to 1.6. mung . This configuration has the advantage that no edges or grooves are pressed into the outer peripheral side of the second hot strand when the second hot strand is being formed, in particular when it is being driven by the second section of the first and second roller.

In a further embodiment, the first driver stand has a first adjustment device, the first adjustment device being designed to move the first roller between a first position and a second position. In the first position, a first distance between the first roller and the second roller is smaller than in the second position of the first roller. It is particularly advantageous here if the first roller is in the first position for guiding the second hot bar and the first roller is held in the second position by the adjustment device for guiding the first hot bar. It is of particular advantage that the first roller and/or the second roller are driven, so that a pressing force that is to be supported by the first adjustment device when driving the second hot strand can be kept low.

In a method for operating the continuous casting plant, the first hot strand with the rectangular cross section is cast from the metallic melt. The casting of the first hot strand can also be referred to as the first operating state of the continuous caster. Alternatively, the second hot strand with an elliptical or circular cross-section is cast from the molten metal. The casting of the second hot strand can also be referred to as the second operating state of the continuous caster. When the first hot strand is guided through the strand guide, the first roller and the second roller rest on both sides of the first hot strand, each with the first section. When the first hot strand is guided through the strand guide, the third roller and the fourth roller are pressed against the first hot strand on both sides in order to reduce the thickness of the first hot strand. When the second hot strand is guided through the strand guide, the first roller and the second roller with the second section lie on both sides tig to the second hot leg and preferably hold the second hot leg. When the second hot strand is guided through the strand guide, the fourth roller supports the second hot strand. In this case, the third roller can be arranged at a distance from the second hot strand, so that flattening of the second hot strand is avoided. Part of the weight of the second hot strand is supported by the fourth roller. This configuration has the advantage that the width of the first hot strand can be driven by means of the second driver stand and its thickness can be reduced. In particular, the second driver stand with the third and fourth rolls is suitable for carrying out a soft reduction, ie when the first hot strand has an already solidified shell but the core is still liquid and the thickness of the hot strand is reduced.

In a further embodiment, when the first hot strand is guided through the strand guide by means of the first and the second roller, a thickness of the first hot strand on the first driver stand is determined. A second distance between the third roller and the fourth roller is determined as a function of the thickness determined on the first driver stand and a predefined target final thickness of the first hot strand at the end of the strand guide. Depending on the second distance determined, the third roller and the fourth roller are positioned relative to one another. This configuration has the advantage that additional measuring rollers in the strand guide can be dispensed with, so that the continuous casting installation is designed in a particularly simple and cost-effective manner.

In a further embodiment, when the first hot strand is guided through the strand guide, the sixth roller of the third driver stand supports the first hot strand with the fourth section and the fifth roller is arranged at a distance from the first hot strand. When the second hot strand is guided through the strand guide, the fifth and sixth rollers rest on both sides of the second hot strand, each with the fifth section. In particular, a deformation, in particular a flattening of the second hot strand, can be driven out/rolled out of the second hot strand by the third pair of rollers. In a further embodiment, when the first hot strand is being guided through the strand guide, the fifth roller and the sixth roller bear against the first hot strand, each with the fourth section. A final gauge of the first hot strand at the third driver stand is determined based on a third distance between the fifth roll and the sixth roll. The determined third distance is taken into account when determining the second distance, with the guidance of the second hot strand through the strand guide, the fifth roller and the sixth roller resting on both sides of the second hot strand with the fifth section and supporting the second hot strand. As a result, the second distance can be regulated to the desired final thickness in a closed loop.

The invention is explained in more detail below with reference to FIGS. Show :

1 shows a schematic representation of a continuous casting plant according to a first embodiment;

FIG. 2 shows a detail B, marked in FIG. 1, of the continuous casting plant shown in FIG. 1;

3 shows a detail of a sectional view along a sectional plane CC shown in FIG. 2 through the first driver frame;

4 shows a detail of a sectional view along an in

Sectional plane D-D shown in FIG. 2 through the second driver frame;

5 shows a detail of a sectional view along an in

Sectional plane E-E shown in FIG. 2 through the continuous casting plant shown in FIG. 2;

FIG. 6 shows a flowchart of a method for operating the continuous casting plant shown in FIGS. 1 to 5; 7 shows a sectional view along that shown in FIG

Sectional plane CC through the continuous casting plant shown in FIG. 1 in the second operating state;

8 shows a sectional view along the sectional plane D-D shown in FIG. 2 through the continuous casting plant shown in FIG. 1 in the second operating state; and

9 shows a sectional view along the sectional plane E-E shown in FIG. 2 through the continuous casting plant shown in FIG. 1 in the second operating state.

In the following FIGS. 1 to 6 and 7 to 9 reference is made to a coordinate system for easier orientation. The coordinate system has an x-axis (longitudinal direction), a y-axis (transverse direction) and a z-axis (height direction).

1 shows a schematic representation of a continuous casting installation 10 .

The continuous casting plant 10 has, for example, a ladle 15 with an outlet pipe 20 . Furthermore, the continuous casting plant 10 comprises a distribution basin 25 arranged below the ladle 15 with a pouring tube 30 running in the z-direction and a stopper 35 arranged in the distribution basin 25 . In addition, the continuous casting plant 10 has a first mold 40 and a second mold 45, with the first mold 40 being inserted into the continuous casting plant 10 below, adjoining the pouring tube 30, by way of example in FIG.

Sectioned along a sectional plane AA (which is designed as an xy plane, for example), the first mold 40 has a rectangular configuration in the sectional plane AA. For example, the first mold 40 has two narrow side plates which are arranged at least essentially parallel to one another and are hidden in FIG. 1 and each run in an xz plane. Furthermore, the first mold 40 has two oppositely arranged wide side plates 50 which are wider than the narrow side panels. The broad side plates 50 can each be arranged to run in a yz plane. The mold 40 , 45 is cooled in the assembled state, preferably water-cooled.

The second mold 45, which is not used in FIG. 1, differs from the first mold 40, so that the second mold 45 has a rounded cross section, in particular a circular cross section, in the sectional plane AA.

The continuous casting plant 10 also has a strand guide 55 . The strand guide 55 is arranged in FIG. 1 below a mold outlet 60 of the first mold 40 or the second mold 45, for example. The mold outlet 60 is arranged on a side of the mold 40 , 45 facing away from the pouring tube 30 .

The continuous casting plant 10 has a first operating state and at least one second operating state. In the first operating state, as shown in FIG. 1, the first mold 40 is inserted into the continuous casting plant 10. In the second operating state, the second mold 45 is inserted into the continuous casting installation 10 and the first mold 40 is dismantled. Thus, in the second operating state, the pouring pipe 30 opens out at the second mold 45 and in the first operating state, the pouring pipe 30 opens out at the first mold 40 .

In the first operating state, a molten metal 65 in the ladle 15 , preferably made of an iron material, in particular a steel material, for example X70, is poured into the distributor basin 25 via the outlet pipe 20 . In the first operating state, the molten metal 65 is introduced from the distributor basin 25 into the first mold 40 via the pouring tube 30, with a first mass flow of the molten metal 65 flowing into the first mold 40 being controlled with the aid of the plug 35. In the first mold 40, the metallic melt 65 cools on its contact surfaces with the first mold 40, in particular on the broad side plates 50 and on the narrow side plates, and solidifies in the process, so that the metallic melt 65 in the form of a first hot strand 70 with a rectangular Cross-section underside at the mold outlet 60 from the first mold 40 exits. At the mold outlet, a conveying direction 75 of the first hot strand 70 essentially runs in the z-direction. When it emerges from the mold outlet 60, the first hot strand 70 has a solidified first shell 100 a few centimeters thick, while a large part of its first cross section is still liquid on the inside.

In the conveying direction 75 of the first hot strand 70, the strand guide 55 is arranged downstream of the first mold 40 in the first operating state. The strand guide 55 has a large number of driver stands 80 , 85 , 90 for guiding and driving both the first hot strand 70 and the second hot strand 260 . In addition, the strand guide 55 can have one or more guide frames 91 .

The guide stand 91 is designed exclusively for holding and/or guiding the first hot strand 70 but not for driving the first hot strand 70 .

In FIG. 1, the continuous casting plant 10 is designed as a curved continuous casting plant. This means that, for example, the first hot strand 70 is guided out of the first mold 40 essentially in the direction of gravity or slightly inclined in the direction of gravity and the strand guide 55 bends the first hot strand 70 from the vertical to the horizontal in the first operating state.

In this case, in FIG. 1, for example, the strand guide 55 has a first driver stand 80, a second driver stand 85 or an arrangement of a plurality of second driver stands 85 and a third driver stand 90. The third driver framework 90 can also be dispensed with. The guide stand 91 is arranged downstream of the mold outlet 60 in relation to the conveying direction 75 of the first hot strand 70 .

The first driver stand 80 is arranged upstream of the other driver stands 85 , 90 in relation to the conveying direction 75 of the first hot strand 70 . The first driver stand 80 is arranged downstream of the guide stand 91 in relation to the conveying direction of the first hot strand 70 . The second driver stand 85 is arranged downstream of the first driver stand 80 in the conveying direction 75 . In the exemplary embodiment, the strand guide 55 has an arrangement of a plurality of second driver stands 85 arranged one after the other, which can be configured essentially identically to one another. In relation to the conveying direction 75 on the downstream side, the third driver stand 90 is arranged after the second driver stand 85 or the arrangement of the second driver stands 85 . In relation to the conveying direction, the arrangement of one or more second driver stands 85 is thus arranged between the first driver stand 80 on the side facing the mold 40, 45 and the third driver stand 90 on the side of the strand guide 55 facing away from the mold 40, 45.

Cooling nozzles 95 can be arranged between the driver frames 80 , 85 , 90 or integrated into the driver frames 80 , 85 , 90 . Cooling water is sprayed onto the first hot leg 70 with the aid of the cooling nozzles 95 in order to further cool the first hot leg 70 . As the distance between the first hot strand 70 and the mold outlet 60 increases, the first hot strand 70 hardens from the first shell 100 inwards towards the core of the first hot strand 70 . After passing through the strand guide 55, a shell thickness of the first shell 100 has increased compared to the first shell 100 at the mold outlet 60, preferably the first hot strand 70 at the end of the strand guide 55 has essentially solidified.

FIG. 2 shows a detail B, marked in FIG. 1, of the continuous casting installation 10 shown in FIG.

The first driver stand 80 has a first pair of rollers 105 . The first pair of rollers 105 has a first roller 110 and a second roller 115 . The first roller 110 can also be referred to as the first inner roller, for example, and is arranged on a side of the first driver frame 80 facing the mold 40 , 45 in relation to the mold 40 , 45 . The second roller 115 is, for example, opposite to a perpendicular relative to the conveying direction 75 of the first hot strand 70 in the strand guide 55 arranged to the first roller 110 . The second roller 115 can also be referred to as the first outer roller. In the first operating state, the first hot strand 70 is guided between the first roller 110 and the second roller 115 so that, for example, the first roller 110 is arranged on top and the second roller 115 is arranged on the underside of the first hot strand 70 .

Furthermore, the first driver stand 80 has a first adjusting device 120 . The first adjusting device 120 is designed to move the first roller 110 between a first position and a second position. A first distance ai between the first roller 110 and the second roller 115 is smaller in the first position than in the second position of the first roller 110 .

In the exemplary embodiment, the first roller 110 and the second roller 115 are each driven and rotatable about an associated first and second axis of rotation 125, 130, respectively. It is also possible for only the first roller 110 or the second roller 115 to be driven. In particular, it is conceivable that the first roller 110 is driven and the second roller 115 is not driven. As a result, the first driver framework 80 is of particularly simple design.

The first axis of rotation 125 of the first roller 110 is aligned parallel to the second axis of rotation 130 of the second roller 115 . The first axis of rotation 125 and second axis of rotation 130 are parallel to the y-axis and run in a direction perpendicular to the conveying direction 75 of the first hot strand 70 between the first roller 110 and the second roller 115 .

In addition, the first driver stand 80 can have a first measuring device 135, with the first measuring device 135 determining the first distance ai between the first roller 110 and the second roller 115. The first measuring device 135 can be connected to a control device (not shown in FIG. 2) of the continuous casting installation 10 and can provide the control device with the determined first distance ai. In the embodiment, for example, eight second driver stands 85 are arranged next to one another in relation to the conveying direction of the first hot strand 70 . The second driver frames 85 are designed essentially identically to one another, so that in the following only the explanation of a second driver frame 85 is discussed. What was explained for the second driver stand 85 also applies correspondingly to the other second driver stands 85 .

The second driver stand 85 has a second adjusting device 140 and a second pair of rollers 141 made up of a third roller 145 and a fourth roller 150 . The third roller 145 is rotatable about a third axis of rotation 155 and is driven. The third roller 145 is essentially arranged at a distance in the conveying direction 75 next to the first roller 110 of the first driver stand 80 . The third roller 145 can thus also be referred to as the second inner roller. The fourth roller 150 is rotatably mounted about a fourth axis of rotation 160 and can be driven in addition to or as an alternative to the third roller 145 . It is of particular advantage if the third and fourth roller 145 , 150 or the third roller 145 are driven. As a result, the second driver framework 85 is of particularly simple design.

The third and fourth axes of rotation 155, 160 run parallel to one another and parallel to the y-axis. The fourth roller 150 can also be referred to as the second outer roller. The fourth roller 150 is essentially arranged at a distance in the conveying direction 75 next to the second roller 115 of the first driver stand 80 .

In the embodiment, the third roller 145 is connected to the second adjustment device 140, the second adjustment device 140 being configured to adjust the third roller 145 between a third position and a fourth position, with a second position being in the third position Distance a2 between the third roller 145 and the fourth roller 150 is smaller or larger than in the fourth position of the third roller 145 . The third driver framework 90 is designed essentially identically to the first driver framework 80 . The third driver stand 90 has a third adjusting device 165 , a third pair of rollers 166 with a fifth roller 170 and a sixth roller 175 and preferably a second measuring device 190 . The second measuring device 190 can also be dispensed with.

The fifth roller 170 is arranged on a side of the third driver stand 90 facing the mold 40 , 45 and can also be referred to as the third inner roller. The fifth roller 170 can be driven and is mounted so that it can rotate about a fifth axis of rotation 180 . The sixth roller 175 is arranged opposite the fifth roller 170 perpendicularly with respect to the conveying direction of the first hot strand 70 between the fifth and sixth rollers 170 , 175 . The sixth roller 175 is arranged on a side facing away from the mold 40 , 45 and can also be referred to as the third outer roller. The sixth roller 175 is rotatably mounted and can be driven about a sixth axis of rotation 185 . The sixth roller 175 can be driven in addition to or as an alternative to the fifth roller 170 . Also, only the fifth roller 170 can be driven and the sixth roller 175 can be non-driven. The fifth and sixth axes of rotation 180 , 185 run parallel to one another and parallel to the y-axis .

The third adjustment device 165 is connected to the fifth roller 170 and is designed to adjust the fifth roller 170 between a fifth position and a sixth position. In the fifth position, a third distance as between the fifth roller 170 and the sixth roller 175 is smaller than in the sixth position of the fifth roller 170 .

FIG. 3 shows a detail of a sectional view through the first driver frame 80 along a sectional plane CC shown in FIG.

The first roller 110 and the second roller 115 of the first pair of rollers 105 are preferably configured identically to one another. The first roller 110 is explained below. What was explained for the first roller 110 also applies analogously to the second roll 115 . The directional information used in the context of the explanation of the first roller 110 with regard to an axial direction and a radial direction each relate to the assigned first axis of rotation 125 of the first roller 110 . Correspondingly, when the characteristics of the first roller 110 are transferred to the second roller 115, they are to be transferred to the second axis of rotation 130.

The first roller 110 and the second roller 115 each have a first running surface 195 on the circumference. The first running surface 195 is related to the respectively assigned first axis of rotation 125 or related to the second axis of rotation 130 in the case of the second roller 115.

The first running surface 195 has a first section 200 , a second section 205 and a third section 210 . The second section 205 directly adjoins the first section 200 in the axial direction with respect to the first axis of rotation 125 . The third section 210 directly adjoins the second section 205 on an axial side facing away from the first section 200 . In the first partial section 200 , the first running surface 195 is configured in a cylindrical manner surrounding the first axis of rotation 125 on the first roller 110 . In the first section 200, the first running surface 195 has a first outer diameter d ₁ .

In the second section 205 the first running surface 195 has a first indentation 215 . The first indentation 215 has a concave shape and is arc-shaped, in particular part-circular. The first indentation 215 extends completely over the second section 205 and connects the first section 200 to the third section 210 . The first indentation 215 preferably has a first curvature R ₁ . The first curvature R ₁ can be greater than half the first outer diameter di of the first section 200 . The first indentation 215 is formed circumferentially around the first axis of rotation 125 . The first indentation 215 extends radially inwards and has a minimum second outer diameter d ₂ . The third subsection 210 is formed in the same way as the first subsection 200 . In the third subsection 210, the first running surface 195 is configured in a cylindrical manner running around the first axis of rotation 125 and has a third outer diameter da.

It is of particular advantage if the first outside diameter di is identical to the third outside diameter d ₃ . In the assembled state of the first roller 110 and the second roller 115 in the first driver frame 80, the first and second rollers 110, 115 are positioned in the axial direction relative to the first and second axis of rotation 125, 130 such that the second section 205 of the first roller 110 and the second partial section 205 of the second roller 115 are arranged completely overlapping one another in the axial direction. An axial overlap means that when two components are projected in the radial direction into a plane in which the first axis of rotation 125 runs, the two components, for example the second section 205 of the first roller 110 and the second section 205 of the second roll 115, completely overlap and thus cover.

The sections 200, 205, 210 each have an associated axial width b 1, b2, b3. In the axial direction, based on the respective first or second axis of rotation 125, 130 at least the second section 205 has the same second axial width b2. A first axial width bi of the first section 200 and a third axial width bi of the first and/or the third section 200 , 210 of the first and/or the second roller 110 , 115 can also be identical.

The first roller 110 and the second roller 115 are arranged opposite one another in the z-direction. The first and second axes of rotation 125 , 130 are arranged in a plane perpendicular to the conveying direction 75 of the first hot strand 70 . In the embodiment, a first distance a ₁ is based on a minimum distance of the first section 200 of the first roller 110 from the first section 200 of the second roller 115 . FIG. 4 shows a detail of a sectional view through the second driver frame 85 along a sectional plane DD shown in FIG.

The third roller 145 and the fourth roller 150 of the second pair of rollers 141 are designed to be identical to one another in the embodiment, with the third roller 145 being explained below by way of example. The statements made for the third roller 145 also apply correspondingly to the fourth roller 150 , with axial and radial directional information being related to the fourth axis of rotation 160 in each case when transferring from the third roller 145 to the fourth roller 150 .

The third roller 145 has a second running surface 220 , the second running surface 220 being configured to run around the third axis of rotation 155 . The third running surface 225 is cylindrical in relation to the third axis of rotation 155 over its entire axial extent. The third running surface 225 has a fourth outer diameter d4, it being possible for the fourth outer diameter d ₄ to be different from the first to third outer diameters d ₁ , d ₂ , d ₃ . The third roller 145 and the fourth roller 150 are arranged at a second distance a2 from one another. In the embodiment, the second distance a2 is related to a distance between the second running surface 220 of the third roller 145 and the second running surface 220 of the fourth roller 150 . In the embodiment, the third axis of rotation 155 and the fourth axis of rotation 160 are arranged in a common plane, which is aligned perpendicular to the conveying direction 75 of the first hot strand 70 .

FIG. 5 shows a detail of a sectional view along a sectional plane E-E shown in FIG. 2 through the continuous casting plant 10 shown in FIG.

In the embodiment, the third driver framework 90 is configured identically to the first driver framework 80 . The third Driver frame 90 the third pair of rollers 166, wherein in the embodiment, for example, the fifth roller 170 can be identical to the first roller 110 and the sixth roller 175 can be identical to the second roller 115 .

In the embodiment, the fifth roller 170 has, for example, a third running surface 225 with a fourth to sixth section 230, 235, 240, with the fifth section 235 being arranged axially in relation to the fifth axis of rotation 180 between the fourth and sixth sections 230, 240 is . In the embodiment, the third running surface 225 has a second indentation 245 in the fifth section 235, which is formed circumferentially around the fifth axis of rotation 180 on the third running surface 225. The fourth and sixth partial section 230 , 240 can be formed in a cylindrical shape running around the fifth axis of rotation 180 . The fifth section 235 connects the fourth section 230 to the sixth section 240 . In the embodiment, the second indentation 245 is concave, in particular arc-shaped, in the sectional view and has a second curvature R ₂ . An axial fourth width b4 of the fifth section 235 can correspond to the second axial width b2 of the second section 205. The second curvature R ₂ can also be selected to be identical to the first curvature R ₁ . Preferably, the second curvature R ₂ is smaller than the first curvature R ₁ .

What was explained for the fifth roller 170 also applies correspondingly to the sixth roller 175 , although in this case directional information should refer to the sixth axis of rotation 185 instead of to the fifth axis of rotation 180 . A third distance a ₃ between the third pair of rollers 166 is related, for example, to a minimum distance of the third running surface 225 in the fourth section 230 of the fifth roller 170 to the fourth section 230 of the third running surface 225 of the sixth roller 175 .

FIG. 6 shows a flowchart of a method for operating the continuous casting plant 10 shown in FIGS. 1 to 5. In a first method step 305, the first mold 40 is installed in the continuous casting installation 10 below the pouring tube 30 (cf. FIG. 1).

In a second process step 310 (cf. FIG. 1) following the first process step 305, the distributor tank 25 is charged with the molten metal 65 and the plug 35 is opened so far that the molten metal 65 flows into the first mold 40, around the first to cast hot strand 70 . The first hot strand 70 solidifies on the first mold 40 . The first hot strand 70 leaves the first mold 40 via the mold outlet 60 . When leaving the mold outlet 60 of the first mold 40, the first hot strand can have a rectangular format with, for example, the dimensions of 20 cm x 30 cm up to and including 25 cm x 35 cm. The first hot strand 70 is guided along the conveying direction 75 into the strand guide 55 . The guide framework 91 holds the first hot strand 70 and prevents the first shell 100 from buckling. Furthermore, cooling water is sprayed onto the first hot strand 70 through the cooling nozzles 95 in order to promote solidification of the core arranged on the inside of the first shell 100 .

At least some of the rollers 110 , 115 , 145 , 150 , 170 , 175 are driven to convey the first hot strand 70 . As a result, the first hot strand 70 is transported through the strand guide 55 along the conveying direction 75 by the rollers 110 , 115 , 145 , 150 , 170 , 175 that are pressed on.

The first hot strand 70 is guided through the guide stand 91 to the first driver stand 80 (cf. FIG. 3). The first roller 110 rests on the first running surface 195 with the first section 200 and the third section 210 on a first side surface 250 of the first hot strip 70 . In the second section 205 the first running surface 195 is arranged at a distance from the first side surface 250 by the first indentation 215 .

The oppositely arranged second roller 115 of the first pair of rollers 105 is located in the first and third sections 200, 210 of the first running surface 195 on a second side surface 255 of the first hot strand 70 which is arranged opposite the first side surface 250 in the z-direction. The first side surface 250 and the second side surface 255 are each formed by the oppositely arranged broad side panels 50 .

In the embodiment, the first adjusting device 120 sets at least the first roller 110 to the second position. The first adjustment device 120 provides a first pressing force F _{P 1} with which the first roller 110 is pressed against the first side surface 215 of the first hot strand 70 . The second roller 115 provides a first counterforce F _G1 which acts against the first pressing force F _{P 1} . The first pressing force F _{P 1} is selected in such a way that an essentially linear contact of the first and third partial section 200, 210 on the respective side surface 250, 255 is ensured. The first pressing force F _{P 1} is also chosen such that deformation of the first shell 100 by the first pair of rollers 105 is essentially prevented. The first hot strand 70 is held and secured against slipping by means of the first pressing force F _{P 1} .

In a third step 315, which can be carried out parallel to the second step 310, the first measuring device 135 determines the first distance a ₁ between the first roller 110 and the second roller 115 and provides the determined first distance a ₁ to the control unit.

In a fourth method step 320, the first hot strand 70 is guided through the arrangement of second driver stands 85 (cf. FIG. 4). In the fourth method step 320, the second adjusting device 140 in each case places the third roller 145 in the fourth position, so that the predefined second distance a ₂ is set. If, as shown in FIGS. 1 and 2, several second driver stands 85 are provided, each of the second adjustment devices 140 sets the second distance a ₂ between the associated second pair of rollers 141 such that with increasing running length of the first Hot strand 70 by arranging second driver stands 85, the second distance a ₂ between the second pair of rollers 141 is reduced in each case compared to the second pair of rollers 141 arranged on the hot-rod upstream side.

The second adjusting device 140 provides a second pressing force F _P2 on the third roller 145 , the second pressing force F _P2 being significantly greater than the first pressing force F _{P 1} . For example, the first pressing force F _P1 can be from 30 kN up to and including 70 kN, in particular from 30 kN up to and including 50 kN, preferably 30 kN, while the second pressing force F _P2 can be, for example, from one finally 800 kN up to and including 1200 kN, in particular 1 . 000 kN. The first pressing force F _{P 1} can be kept low, particularly when the first and second rollers 110, 115 are driven, and for example be closer to the lower interval limit mentioned than to the upper interval limit. As a result, the first driver frame 80 is mechanically exposed to lower loads.

A thickness d of the first hot strand 75, with which the first hot strand 70 is fed to the respective second driver stand 85, is greater than the second distance a ₂ . The fourth roller 150 provides a second opposing force F _G2 directed against the second pressing force F _P2 . The thickness d of the first shell 100 on the second driver frame 85 is reduced by means of the second pressing force F _P2 and the second counterforce F _G2 . The thickness d of the first hot strand 70 is successively reduced across the arrangement of second driver stands 85 . In this case, a soft reduction is carried out, in which the core of the first hot strand 70 has not yet completely solidified and the thickness reduction can therefore take place particularly well before the first hot strand 70 is fed, for example, to a roughing train arranged downstream of the continuous casting plant 10 . Because the third and fourth rollers 145 , 150 are driven, the second pressing force _FP2 and the second counterforce _FG2 are reduced compared to an embodiment of the second driver frame 85 without a drive for the second pair of rollers 141 . However, it is pointed out that it is sufficient if only the third roller 145 or the fourth roller 150 of each second driver stand 85 is driven. In this case, in particular, only the third roller 145 can be driven and the fourth roller 150 can be dispensed with. A particularly simple and cost-effective strand guide 55 can thus be provided, particularly when carrying out the soft reduction.

In a fifth method step 325, the first hot strand 70 is guided through the third driver stand 90 (cf. FIG. 5). The fifth roller 170 is in the sixth position and is in contact with the fourth and sixth sections 230 , 240 against the first side surface 250 . Likewise, the third running surface 225 of the sixth roller 175 rests on the underside of the second side surface 255 of the soft-reduced first hot strand 70 with the fourth and sixth sections 230 , 240 .

In order to ensure that the third running surface 225 of each of the fifth and sixth rollers 170, 175 rests securely against the respectively associated side surface 250, 255 of the first hot strand 70, the third adjusting device 165 presses the fifth roller 170 with a third pressing force F _P3 in the sixth position pressed against the first side surface 250 of the first hot bar 70 . The third pressing force F _P3 is significantly smaller than the second pressing force F _P2 . The sixth roller 175 provides a third opposing force F _G3 TO the third pressing force F _P3 directed against the third pressing force F _P3 . For example, the third pressing force F _P3 can be from 30 kN up to and including 70 kN, in particular 50 kN. The third pressing force F _P3 is selected in such a way that the first shell 100 of the first hot strand 70 is essentially not deformed. The first hot strand 70 is held and secured against slipping by means of the third pressing force F _P3 .

The third distance as is smaller than the first distance a ₁ and corresponds to a final thickness d _E of the first hot strand 70 at the end of the strand guide 55 . The second measuring device 190 determines the third distance as and provides the information about the third distance as to the control unit. The control unit can If the determined first distance a ₁ and third distance a ₃ and a predefined desired end thickness of the first hot strand 70 were at the end of the strand guide 55, the second distance a ₂ of the second pair of rollers 141 would be determined and the second adjusting device 140 based on the determined second Control distance a ₂ so that the second pair of rollers 141 is arranged in the determined second distance a ₂ . In a closed loop, the control unit can regulate the strand guide 55 for the soft reduction in such a way that the final thickness d _E at the end of the strand guide 55 on the first hot strand 70 corresponds to the desired final thickness of the first hot strand 70 with particular precision.

In a sixth method step 330, the continuous casting of the first hot strand 70 is completed, so that the plug 35 closes the shroud 30. As a result, the first mold 40 runs empty and the first hot strand 70 is guided out of the continuous casting plant 10 by the strand guide 55 .

In a seventh method step 335 following the sixth method step 330 , the continuous casting installation 10 is switched from the first operating state to the second operating state and the first mold 40 is replaced by the second mold 45 .

FIG. 7 shows a sectional view along the section plane CC shown in FIG. 2 through the continuous casting plant 10 shown in FIG. 1 in the second operating state. FIG. 8 shows a sectional view along the section plane D-D shown in FIG. 2 through the continuous casting plant 10 shown in FIG. 1 in the second operating state. 9 shows a sectional view along the sectional plane E-E shown in FIG. 2 through the continuous casting plant 10 shown in FIG. 1 in the second operating state.

In an eighth method step 340 following the seventh method step 335 , the metallic melt 65 is conveyed from the ladle 15 into the distributor basin 25 . Furthermore, the stopper 35 is opened so that the metallic melt 65 is conducted into the second mold 45 via the pouring tube 30 . at the contact surface, the metallic melt 65 solidifies in the second mold 45 to form a second hot strand 260 and forms a second shell 265 which has an elliptical cross section, preferably a circular cross section. A maximum radial extension e of the second hot strand 2 60 is preferably smaller than the thickness d of the first hot strand 70 at the mold outlet 60 . Due to the smaller radial extent e of the second hot bar 260 , the second shell 265 can be designed to be significantly stiffer and more robust in relation to the second hot bar 260 than in the first hot bar 70 . This ensures that flattening of the second hot strand 260 is kept to a minimum by the guide stand 91 .

Furthermore, the first roller 110 is moved into the first position by the first adjusting device 120, so that compared to the previous method steps 305 to 330 the first roller 110 is arranged at a smaller first distance a ₁ from the second roller 115 than during the casting of the rectangular first hot billet 70 . The third roller 145 is moved into the third position by the second adjusting device 140, so that the second distance a ₂ is reduced or increased compared to the first to seventh method steps 305 to 335. The fifth roller 170 is moved into the fifth position by the third adjusting device 165, so that the third distance a ₃ is reduced compared to the first to sixth method steps 305 to 330.

In a ninth method step 345 (cf. FIG. 7), the first roller 110 is pressed by the first adjusting device 110 against the second hot strand 260 with a fourth pressing force F _P4 . The second roller 115 provides a fourth counterforce F _G4 directed against the fourth pressing force F _P4 , the fourth pressing force F _P4 being higher than the first pressing force F _P1 . For example, the fourth pressing force F _P4 can be 40 kN to 80 kN, in particular 50 kN. The first and third sections 200, 210 are spaced apart from the second hot bar 260, while the second hot bar 260 in the second section 205 rests against the first running surface 195 on the circumference. The first curvature R ₁ of the first indentation 215 is selected such that the first curvature R ₁ is greater by a factor of 1.2 to 1.6 than an outer curvature RA of the outer peripheral side 270 of the second hot strand 260 . The second hot leg 260 can, for example, have an outer curvature of 7 cm up to and including 13 cm, so that a diameter of the second hot leg 260 is from 14 cm up to and including 26 cm. By pressing the first pair of rollers 105 against the outer peripheral side 270 of the second hot strand 260, a flattening, resulting from the second hot strand 260 resting against the guide stand 91, can be formed out of the second hot strand 260 or be rolled out. As a result, the second hot strand 260 has a particularly small deviation from a desired cross-sectional shape. For example, the second hot strand 260 shown in FIG. 7 has a particularly small tolerance to a circular shape. The second hot strand 260 is also held and secured against slipping by means of the fourth pressing force F _P4 .

After passing through the first driver stand 85, the second hot strand 260 is guided through the second driver stand 85 (cf. FIG. 8). The fourth position of the third roller 145 is selected such that the second distance a ₂ is greater than a maximum radial extension e of the second hot strand 260 . The second hot strand 260 rests only with its mass on the fourth roller 150 and the third roller 145 is not pressed against the second hot strand 260, so that flattening of the top and/or bottom of the second hot strand 260 is prevented or kept to a minimum will . The third roller 145 exclusively prevents the second hot strand 260 from bulging upwards in that the second hot strand 260 strikes the top side of the second running surface 220 during buckling and is thus guided within the arrangement of the second driver stands 85 in the direction of the third driver stand 90 .

Because the second pair of rollers 141 is driven, a reliable transport of the second hot strand 260 within the strand guide 55 is ensured.

After passing through the second driver stands 85, the second hot strand 260 is guided through the third driver stand 90 (cf. FIG. 9). The fifth roller 170 is in the fifth position and is pressed against the outer peripheral side 270 of the second hot strip 260 in the fifth section 235 with a fifth pressing force F _P5 . The sixth roller 175 provides a fifth counterforce F _G5 in the opposite direction to the fifth pressing force F _P5 and rests with the fifth partial section 235 on the outer peripheral side 270 of the second hot strand 260 . The fifth pressing force F _P5 can be significantly greater than the third pressing force F _P3 . For example, the fifth pressing force F _P5 can be from 50 kN up to and including 100 kN, in particular 70 kN.

The third distance a ₃ can be slightly smaller than the first distance a ₁ . The third distance a ₃ can also be identical to the first distance a ₁ . The second indentation 245 of the fifth and sixth rollers 170, 175 can use the fifth pressing force F _P5 and the fifth counterforce F _G5 to flatten the second roller pair 141 from the second hot strand (for example by resting on the fourth roller 150). 260 are rolled, so that after passing through the third driver stand 90, the second hot rod 260 is particularly precise with respect to the geometric shape of the outer peripheral side 270. In particular, the outer peripheral side 270 has a particularly good round shape. The second hot strand 260 is also held and secured against slipping by means of the fifth pressing force F _P5 .

After passing through the strand guide 55, the second hot strand 260 can be used, for example, to produce high-precision tubes. For this purpose, either the hot second hot strand 260 can be fed directly to the forming machine or the second hot strand can be cut off into billets.

The configuration of the continuous casting plant 10 described above and the method for operating the continuous casting plant 10 has the advantage that both the rectangular first hot strand 70 for sheet metal production and billet material for tube production can be cast by means of the continuous casting installation 10 . In order to convert the continuous casting plant 10 between the two operating states, it is only necessary to switch between the first mold 40 for casting the rectangular first hot strand 70 and the second mold 45 instead of the first mold 40 . A further conversion, in particular of the strand guide 55, is not necessary.

Furthermore, the final thickness _dE of the first hot strand 70 after passing through the strand guide 55 can be determined particularly well by measuring after passing through the second driver stand 85 on the third driver stand 90 and the second adjusting device 140 can thereby be controlled by the control unit. This eliminates the need for additional measuring rollers.

Furthermore, the profiling of the first and second rollers 110, 115 of the first driver stand 80 and the fifth and sixth rollers 170, 175 of the third driver stand 90 can ensure centering of the second hot strand 260 as it passes through the strand guide 55. As a result, in addition to the improved dimensional accuracy of the cross section of the second hot strand 260, drifting of the second hot strand 260 in the strand guide 55 is avoided.

Alternatively, it would also be conceivable for the second measuring device 190 to be dispensed with and for the fifth roller 170 to be arranged in the sixth position at a distance from the first hot strand 70 in the first to sixth method steps 305 to 330 . As a result, when the first hot strand 70 is guided through the third driver stand 90, the first hot strand 70 rests on the sixth roller 175 only on the second side surface 255 in the fourth and sixth sections 230, 240 of the sixth roller 175, with the sixth roller 175 den first hot strand 70 is supported at the bottom. Due to the arrangement at a distance from the first hot strand 70 , the fifth roller 170 does not assume any further function. As a result, the strand guide 55 is of particularly simple design. reference character list

10 continuous caster

15 pan

20 outlet pipe

25 distribution tanks

30 pouring tube

35 plugs

40 first mold

45 second mold

50 broadside plate

55 strand guide

60 mold outlet

65 metallic melt

70 first hot leg

75 conveying direction

80 first driver scaffold

85 second driver framework

90 third driver scaffold

91 guide framework

95 cooling nozzle

100 first shell

105 first pair of rollers

110 first roll

115 second roll

120 first adjusting device

125 first axis of rotation

130 second axis of rotation

135 first measuring device

140 second adjusting device

141 second pair of rollers

145 third roll

150 fourth roll

155 third axis of rotation

160 fourth axis of rotation

165 third adjusting device

166 third pair of rollers

170 fifth roll 175 sixth roll

180 fifth axis of rotation

185 sixth axis of rotation

190 second measuring device

195 first tread

200 first section

205 second section

210 third section

215 first indentation

220 second tread

225 third tread

230 fourth section

235 fifth section

240 sixth section

245 second indentation

250 first face

255 second face

260 second hot leg

265 second shell

270 outer peripheral side

305 first process step

310 second process step

315 third process step

320 fourth process step

325 fifth process step

330 sixth process step

335 seventh method step

340 eighth process step

345 ninth method step a ₁ first distance a ₂ second distance a ₃ third distance d ₁ first outer diameter d ₂ second outer diameter d ₃ third outer diameter d4 fourth outer diameter R ₁ first curvature R ₂ second curvature b ₁ axial first width b ₂ axial second width b ₃ axial third width b ₁ axial fourth width d thickness d _E final thickness R _A outer curvature e maximum radial extent

F _P1 first pressing force F _P2 second pressing force F _P3 third pressing force F _P4 fourth pressing force F _{P 5} fifth pressing force F _G1 first opposing force F _G2 second opposing force F _G3 third opposing force F _G4 fourth opposing force F _G5 fifth opposing force

Claims

patent claims

1. Continuous casting plant (10) for alternately casting a first hot strand (70) with a rectangular cross section and a second hot strand (260) with an elliptical or circular cross section from a metallic melt (65),

- Having a strand guide (55) with at least one first driver stand (80) and one in the conveying direction (75) of the first hot strand (70) arranged offset second driver stand (85),

- wherein the first driver frame (80) has a first pair of rollers (105) with a first roller (110) and a second roller (115) and the second driver frame (85) has a second pair of rollers (141) with a third roller (145) and a fourth roller (150),

- the first hot strand (70) or the second hot strand (260) being able to be guided through between the first pair of rollers (105) and the second pair of rollers (141),

- the first roller (110) and the second roller (115) each having a first running surface (195) on the circumference, each of which is cylindrical in a first section (200),

- the third roller (145) and fourth roller (150) each having a cylindrical second running surface (220),

- wherein the first section (200) of the first and second roller (110, 115) and the third and fourth roller (145, 150) are each designed to guide the first hot strand (70),

- The first roller (110) and the second roller (115) each in a second section (205) of the first running surface (195) adjoining the first section (200) in a direction inclined to the conveying direction (75). have a first indentation (215) formed circumferentially on the first running surface (195),

- The first indentation (215) of the first and second roller (110, 115) being designed in each case for guiding the second hot strand (260).

2. continuous casting plant (10) according to claim 1,

- wherein the first roller (110) and/or second roller (115) has a third section (210),

- the third section (210) adjoining the direction of the second section (205) on a side of the second section (205) facing away from the first section (200),

- wherein in the third section (210) the first roller (110) and/or second roller (115) is designed in a cylindrical manner.

3. continuous casting plant (10) according to claim 2,

- wherein the first section (200) has a first outer diameter (d ₁ ) and the third section (210) has a further outer diameter (d ₃ ) which is essentially identical to the first outer diameter (d ₁ ).

4. Continuous casting plant (10) according to one of the preceding claims, wherein the continuous casting plant (10) can be operated in a first operating state and a second operating state, wherein in the first operating state a first mold (40) with a rectangular mold cross section and in the second operating state, a second mold (45) with a circular or elliptical mold cross-section is inserted into the continuous casting plant (10), with the first mold (40) being formed in the first operating state, the first hot strand (70 ) with the rectangular cross-section and to cast the second hot strand (260) with the circular or elliptical cross-section from the molten metal (65) in the second operating state.

5. Continuous casting plant (10) according to one of the preceding claims, wherein the first driver stand (80) has a first measuring device (135), - Wherein the first measuring device (135) is designed to determine a first distance (a ₁ ) of the first roller (110) to the second roller (115).

6. continuous casting plant (10) according to any one of the preceding claims che, - having at least a third driver stand (90), - wherein the third driver stand (90) a third pair of rollers (166) each with a rotatably mounted fifth roller (170) and a sixth roller (175), - the third driver stand (90) being arranged after the second driver stand (85) and the second driver stand (85) after the first driver stand (80) in relation to the conveying direction (75) of the first hot strand (70). is, - wherein the fifth roller (170) and the sixth roller (175) each have a third running surface (225) on the circumference, which is cylindrical in each case in a fourth section (230), - wherein in each case on the fourth section (230) in the direction subsequent fifth section (235) of the third running surface (225) the third running surface (225) has a peripheral on the third running surface (225) trained de second indentation (245), - wherein the vie The fourth section (230) of the fifth roller (170) and the sixth roller (175) are each designed to rest against the first hot strand (70) on both sides, - the second indentation (245) of the fifth and sixth roller (170, 175) is designed in each case to guide the second hot strand (260).

7. continuous casting plant (10) according to claim 6,

- wherein the third driver frame (90) has a second measuring device (190),

- Wherein the second measuring device (190) is designed to determine a third distance (as) of the fifth roller (170) to the sixth roller (175).

8. Continuous casting plant (10) according to one of the preceding claims che, - wherein the first indentation (215) is concave and has a curvature (R ₁ ), wherein the first indentation (215) is formed, an outer peripheral side (270) forming the second hot strand (260) with an outer curvature (R _A ), - wherein the curvature (Ri) is greater than the outer curvature (R _A ), - wherein the first curvature (R ₁ ) is preferably increased by at least a factor of 1, 2 to 1.6 greater than the outer curvature (R _A ).

9. Continuous casting plant (10) according to any one of the preceding claims che, - wherein the first driver stand (80) has a first adjustment device (120), - wherein the first adjustment device (120) is formed, the first roller (110) between a first position and a second position, - wherein in the first position a first distance (ai) between the first roller (110) and the second roller (115) is smaller than in the second position of the first roller (110 ).

10. Method for operating a continuous casting plant (10) according to one of the preceding claims, - wherein the first hot strand (70) with the rectangular cross-section is produced from the metallic melt (65) or the second hot strand (260 ) is cast with an elliptical or circular cross-section, - with the first hot strand (75) being guided through the strand guide (55), the first roller (110) and second roller (115) on both sides of the first hot strand (70), each with the first section (200) for guiding the first hot strand (55), - Wherein the guidance of the first hot strand (75) through the strand guide (55), the third roller (145) and fourth roller (150) are pressed on both sides of the first hot strand (70) to the first hot strand (70) in its thickness ( d) to reduce, - wherein when the second hot strand (260) is guided through the strand guide (55), the first roller (110) and the second roller (115) with the second section (205) rest on both sides of the second hot strand (260). and holding the second hot bar (260), - wherein when the second hot bar (260) is guided by the bar guide (55), the fourth roller (150) supports the second hot bar (260).

11. The method according to claim 10, - wherein when guiding the first hot strand (75) through the strand guide (55) by means of the first roller (110) and the second roller (115) a thickness (d) of the first hot strand (70) on the first driver stand (80) is determined, - a second distance (a ₂ ) between the third roller (145 ) and the fourth roller (150) is determined, - the third roller (145) and the fourth roller (150) being positioned relative to one another as a function of the determined second distance (a ₂ ).

12. The method according to claim 10 or 11 and claim 6, - wherein when the first hot strand (75) is guided through the strand guide (55), the sixth roller (175) of the third driver stand (90) cuts the first hot strand (70) with the fourth section (230) supports and the fifth roller (170) is arranged at a distance from the first hot strand (70), - wherein when the second hot strand (260) is guided through the strand guide (55), the fifth roller (170) and sixth Roller (175) bear on both sides of the second hot strand (260), each with the fifth section (235).

13. The method according to claim 10 or 11 and claim 6, - wherein when guiding the first hot strand (75) through the strand guide (55), the fifth roller (170) and sixth roller (175) on the first hot strand (70) each with the fourth section (230), - wherein a final thickness (d _E ) of the first hot strand (70) is determined on the basis of a third distance (a ₃ ) between the fifth roller (170) and the sixth roller (175), - wherein the determined third distance (a ₃ ) is taken into account when determining the second distance (a ₂ ), - with the guidance of the second hot strand (260) through the strand guide (55), the fifth roller (170) and sixth roller (175) on both sides of the second hot strand (260) with the fifth section (235) and support the second hot strand (260).