MELT FEEDING FOR STRIP CASTING SYSTEMS

Abstract

A strip casting system for aluminium and/or aluminium alloys comprising a casting furnace and a revolving chill mould having a casting gap. The revolving chill mould is designed as a roll pair, roller pair, caterpillar pair or belt pair. The strip casting system has an active means for transporting metal melt from the casting furnace to the casting gap and a casting region arranged in front of the casting gap. The casting region is delimited on one side by the revolving chill mould. A melt pool is formed in the casting region, from which metal melt flows or is drawn into the casting gap. The casting furnace is connected to the casting region by a pipe system with means for feeding the metal melt into the casting region, which can feed the metal melt to the casting region below the surface of the melt pool formed in the casting region.

Claims

1. A strip casting system for aluminium and/or aluminium alloys comprising at least one casting furnace and at least one revolving chill mould having a casting gap, wherein the at least one revolving chill mould is designed as a roll pair, roller pair, caterpillar pair or belt pair, wherein the strip casting system has at least one active means for transporting aluminium or aluminium alloy melt from the casting furnace to the casting gap, wherein the strip casting system has a casting region arranged in front of the casting gap, wherein the casting region is delimited on at least one side by the revolving chill mould and the casting region is designed in such manner that an aluminium or aluminium alloy melt pool is formed in the casting region, from which aluminium or aluminium alloy melt flows or is drawn into the casting gap, wherein the casting furnace is connected to the casting region by a pipe system, wherein the strip casting system comprises means for feeding the aluminium or aluminium alloy melt into the casting region, which can feed the aluminium or aluminium alloy melt to the casting region below the surface of the aluminium or aluminium alloy melt pool formed in the casting region.

2. The strip casting system according to claim 1, wherein the at least one active means for transporting metal melt comprises a means for pressurising and/or a means for pumping the metal melt.

3. The strip casting system according to claim 1, wherein the at least one active means for transporting aluminium or aluminium alloy melt comprises a pressure furnace, in particular a low-pressure furnace.

4. The strip casting system according to claim 1, wherein the casting furnace is configured as a low-pressure furnace.

5. The strip casting system according to claim 1, wherein the strip casting system is a vertical strip casting system.

6. The strip casting system according to claim 1, wherein the strip casting system has means for regulating the volume flow of the aluminium or aluminium alloy melt to the casting gap and/or the height of the melt level in the casting gap.

7. The strip casting system according to claim 1, wherein the casting region has at least one side dam, wherein the at least one side dam has at least one feed opening for aluminium or aluminium alloy melt.

8. The strip casting system according to claim 1, wherein the casting region has at least two, preferably three, feed openings for aluminium or aluminium alloy melt.

9. A method for feeding an aluminium or aluminium alloy melt to the casting gap in a strip casting system for aluminium and/or aluminium alloys comprising at least one casting furnace and at least one revolving chill mould designed as a roll pair, roller pair, caterpillar pair or belt pair with a casting gap, in particular carried out with a strip casting system according to claim 1, wherein the aluminium or aluminium alloy melt is actively transported into a casting region arranged in front of the casting gap, wherein the casting region is delimited on at least one side by the revolving chill mould and the casting region is designed in such manner that an aluminium or aluminium alloy melt pool is formed in the casting region, from which aluminium or aluminium alloy melt flows or is drawn into the casting gap, wherein the aluminium or aluminium alloy melt is actively fed to the casting region below the surface of the aluminium or aluminium alloy melt pool formed in the casting region.

10. The method according to claim 9, wherein the at least one casting furnace is pressurised to transport the aluminium or aluminium alloy melt.

11. The method according to claim 9, wherein the aluminium or aluminium alloy melt is transported at least in sections against the direction of gravity (G).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Further configurations and advantages of the invention can be drawn from the following detailed description of a number of exemplary embodiments of the present invention, in particular in combination with the drawings, in which:

[0051] FIG. 1 shows a schematic sectional view of an exemplary embodiment of a vertical strip casting system according to the invention,

[0052] FIG. 2 shows a perspective representation of the casting region of the exemplary embodiment from FIG. 1,

[0053] FIG. 3 shows a schematic sectional view of a further exemplary embodiment of a horizontal strip casting system not according to the invention,

[0054] FIG. 4 shows a schematic sectional view of a further exemplary embodiment of a horizontal strip casting system according to the invention and

[0055] FIG. 5 shows a schematic representation of a further exemplary embodiment of a horizontal strip casting system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0056] FIG. 1 shows a strip casting system 1 comprising a revolving chill mould 2 with a casting gap 21, with the revolving chill mould 2 being formed by two rolls 22, 23, and a casting furnace 3, with the strip casting system 1 having an active means 4 for transporting metal melt 5 from the casting furnace 3 to the casting gap 21. The strip casting system 1 here is a vertical strip casting system 1. In this example, the active means 4 for transporting metal melt 5 comprises a means 4 for pressurising the metal melt 5 so that the same can be actively transported by the active means 4 from the casting furnace 3 to the casting gap 21. In this example, the casting furnace 3 is configured as an active means 4, in particular as a low-pressure furnace 4. The exemplary strip casting system 1 has a casting region 6 arranged in front of the casting gap 21, which is configured as a casting gusset 6 and is arranged above the casting gap 21. The casting furnace 3, 4 is connected to the casting gusset 6 by a pipe system 42, 43, which comprises heatable ceramic pipes 42, 43. Furthermore, the casting gusset 6 has two side dams 62, with a side dam 62 having a feed opening 46 for the metal melt 5. The feed opening 46 is provided here as a means 46 for feeding the metal melt 5 into the casting gusset 6, via which the metal melt 5 can be fed to the casting region 6 below the surface of the melt pool 52 formed in the casting region. The exemplary strip casting system 1 thus comprises means 46 for feeding the metal melt 5 to the casting region 6, which can feed the metal melt 5 to the casting region 6 below the surface of a melt pool 52 formed in the casting region 6. In this case, the metal melt 5 is, for example, an aluminium melt 5.

[0057] If the surface of the melt pool 53 is pressurised in the low-pressure furnace 3, 4, for example via an air or gas supply 32, for example with 0.1 to 1.0 bar, preferably 0.5 and 0.6 bar, the metal melt 5 can be transported via the riser pipe 43 and the heated pipe 41 to the casting region 6 against the direction of gravity G. This enables particularly calm and gentle melt guidance to the melt pool 52 without the surface of the melt pool 52 being penetrated or disturbed by movements of the surface or turbulence of the metal melt. Since the metal melt 5 is transported against gravity, the exemplary strip casting system 1 is configured very safely, since the metal melt 5 falls back into the low-pressure furnace 3, 4 in the event of a system failure, in particular through the riser pipe 43. In addition, an easy regulation of the volume flow of the metal melt to the casting gap is enabled. For this purpose, the exemplary strip casting system 1 has means for regulating the volume flow of the metal melt 5 in the casting gap 21 and/or the height of the melt level in the casting gap 21 in the form of a control loop. For this purpose, the control loop draws on measured values from a fill level sensor 61, which measures the fill level or level of the melt pool 52 in the casting region 6, and also on a pressure sensor 31, which measures the pressure in the low-pressure furnace 3, 4. If, for example, a lowering of the fill level of the melt pool 52 is detected by means of the fill level sensor 61, the pressure in the low-pressure furnace 3, 4 can, for example, be increased in a controlled manner in order to bring the fill level back to an optimal fill level. In contrast to the gravity-based conventional feeding system, the exemplary strip casting system 1 can thus be actively and precisely regulated with fast response times.

[0058] FIG. 2 shows, in a perspective view, the casting region 6 of the exemplary vertical strip casting system 1 from FIG. 1. The revolving chill mould 2 of the exemplary strip casting system 1 is thereby formed by two rolls 22, 23. The casting region 6 is designed here as a casting gusset 6 and is formed by the rolls 22, 23 of the revolving chill mould 2 and two side dams 62. In this case, a side dam 62 has a feed opening 46 via which a metal melt 5 can be fed to the casting region 6 below the surface of a melt pool 52 formed in the casting region. Compared to conventional methods, which work with an immersion pipe from a tundish located above the melt, the tundish can be dispensed with, in which oxide formation and the described negative effects, such as uncontrolled oxide entry into the melt, occur.

[0059] FIG. 3 shows a strip casting system 1 not according to the invention comprising a revolving chill mould 2 with a casting gap 21, with the revolving chill mould 2 being formed by two (dam block) chains 25, 26 and a casting furnace 3, with the strip casting system 1 having an active means 4 for transporting metal melt 5 from the casting furnace 3 to the casting gap 21. Here, the strip casting system 1 is a horizontal or tilted strip casting system 1. In this example, the active means 4 for transporting metal melt 5 comprises a means 4 for pumping the metal melt 5 in the form of an electromagnetic metal pump 4, so that the metal melt 5 can be transported from the casting furnace 3 from below into the distributor nozzle 63. The casting region 6 is, for example, formed by the closed distributor nozzle 63.

[0060] FIG. 4 shows a further strip casting system 1 according to the invention comprising a casting furnace 3 and a revolving chill mould 2 with a casting gap 21, with the revolving chill mould 2 being formed by two rolls 22, 23, with the strip casting system 1 having an active means 4 for transporting metal melt 5 from the casting furnace 3 to the casting gap 21. Here, the strip casting system 1 is a horizontal or tilted strip casting system 1. The metal melt 5 is actively transported via the metal pump 4 from below through the feed opening 46 into the casting region 6. A melt pool 52 is formed here in the casting region 6.

[0061] FIG. 5 shows an exemplary strip casting system, with the casting region 6 having at least three feed openings 46 for metal melt. Two feed openings 46 are arranged in the width direction substantially at opposite ends of the casting region 6. A third feed opening 46 is arranged centrally between the two other feed openings 46. The metal melt 5 is actively transported from the casting furnace 3 via the metal pump 4 from below through the feed opening 46 into the casting region 6. As shown in FIG. 6, the feeding from the furnace can be branched via the pipe 41 into a plurality of strands and fed through a plurality of pipes perpendicular thereto via a plurality of feed openings 46 to the casting region 6, in particular a casting gusset and/or a distributor nozzle against the direction of gravity G. Thus, for example, melt can be fed into the distribution system at a plurality of points simultaneously at the same temperature and speed and thus it can be achieved that a homogeneous isothermal melt flows over the entire width in the outlet into the casting gap 21.

[0062] The described exemplary embodiments of the strip casting system 1 each enable the uniform feeding of aluminium melt 5 into casting regions 6 or to casting gaps 21, so that the cast rolling processes can be stabilised, productivity improved and material defects avoided. This can, for example, be achieved by the metal melt 5 being fed under the surface of a melt pool 52 to the casting roll gap 21 such that the surface of the existing melt pool 52 is not penetrated or disturbed by bath movement. This avoids oxygen contact of the inflowing metal melt 5 and thus reduces the total amount of oxides formed. Furthermore, for example, there is an intact, calm oxide layer 54 on the surface of the melt pool 52, which is not mixed into the melt and which protects the melt pool 52 from further oxidation. This prevents non-metallic inclusions in the strip produced.

[0063] This means that the strip casting system 1 can be operated at the optimum speed without the risk of local melt penetrations. The strip quality can be kept consistent over the entire width. Uneven solidification over the width of the casting gap and thus, for example, local penetrations of melt through the casting gap can thus be avoided. This can also prevent surface flaws, cracks in the strip or casting breaks.

[0064] Furthermore, a melt introduced from below or laterally can be distributed in individual strands over the casting width, i.e. the width of the casting gap, so that a homogeneous inflow to the casting gap can be achieved at a uniform temperature and/or uniform speed. This can improve the uniformity of product properties over the strip width and further increase the productivity of the system by reducing the risk of local melt penetrations.

[0065] The described exemplary embodiments may also be advantageous for reasons of occupational safety. If problems occur in the molten area of the system, the transport system can be switched off and the residual melt in the system falls immediately back into the furnace with gravity G through the riser pipe 42. There is no further flow of the melt into the casting region.

[0066] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0067] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0068] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.