EP0625387B1 - Strip casting machine for metals - Google Patents

Abstract

The strip casting machine has a casting nozzle (10), displaceable in the direction of flow (F) of the molten metal and adjustable perpendicular thereto, for feeding molten metal into the adjustable rolling nip (30) between rotating moulds (26, 28). The casting nozzle (10) consists of an upper and a lower nozzle element (14, 16) or, in the case of a vertical strip casting machine, of a left-hand and a right-hand nozzle element, articulated on a melt distribution trough and of two side limiters which form a slot-shaped outlet opening (20) for the molten metal. One or both of the nozzle elements (14, 16) is adjustable, at least in the region of the outlet opening (20). During the operation of the strip casting machine, the casting nozzle (10) is, for start-up, advanced with its outlet opening (20) into a starting position (S) and then pulled back into a working position (W), the outlet opening (20) being expanded, adapting to the rotating moulds (26, 28) in the process. <IMAGE>

Description

The invention relates to a strip casting installation for metals, especially for aluminum and aluminum alloys, with a slidable in the direction of flow of the liquid metal and vertically adjustable pouring nozzle for feeding of liquid metal in the adjustable roll gap between rotating molds, the pouring nozzle consisting of two nozzle elements articulated to a melt distribution trough and two side delimiters, which are slit-shaped Form the outlet opening for the liquid metal. At The casting nozzle has horizontal or inclined belt casting systems an upper and a lower, in vertical strip casting systems a left and a right nozzle element. Further concerns the invention is a method for operating the strip caster.

Here and in the following are in particular horizontal belt casting machines described. However, it can also slant after above, e.g. 15 °, or poured obliquely down and the invention be used. Likewise, the invention for vertical band casting would be used, it would just have to some terminology changes that are obvious to the expert on which here and in the following the Clarity is mostly omitted.

Known belt casting systems have a first variant two casting rolls arranged one above the other (e.g. Lauener Rollcaster), according to a second variant two on top of each other continuous casting belts (e.g. Hazelett) or caterpillars (e.g. Lauener Block Caster), which from a machine frame be held or arranged in a housing are. The following are all types of those forming the casting gap Chill molds, according to the preferred embodiment of the invention, referred to as casting rolls. Analogous However, there are always continuous casting belts or caterpillars recorded by strip casting devices.

In the area of the roll or casting gap is in the working position a nozzle between the two casting rolls, which is usually fixed on the machine frame. A pouring trough fed by a gutter system, from a specialist Called melt distribution trough, conducts liquid metal into the nozzle, the flowing metal solidifies between the casting rollers and emerges as a partially rolled strip. This pouring nozzle can be turned on and off together with its nozzle holder be expanded, but accessibility is, in particular severely hampered by machine frame or housing.

Today, tapes are made down to the strip casting process a thickness of about 2 mm, in particular 3 to 7 mm, cast, something very high about the nozzle itself and its positioning Demands.

The nozzle must not only prevent erosion or dissolution in aggressive, Resist liquid metal, it must not have high thermal conductivity, because otherwise the liquid Metal could solidify in the nozzle and has to roughen it Resist foundry.

From US, A 2752649, for example, has long been a more suitable one Material known for a pouring nozzle. This must be so be positioned exactly so that on the one hand there is an unwanted Parts do not damage the roller surfaces, but on the other hand, not so between the nozzle and the casting roller large gaps are formed that the liquid Do not put metal between the nozzle and the surface of the casting roller can penetrate. For casting aluminum, for example is a distance of the nozzle to the casting roll of 0.2 mm considered optimal, penetration above 0.5 mm can hardly be prevented by molten metal.

From the the next state of the art EP, A1 0443204 is a horizontally displaceable and Height-adjustable pouring nozzle for feeding liquid Known metal in a roll gap, in which the metal feed not interrupted while positioning a nozzle must become. This allows the pouring nozzle to be replaced without downtime.

EP, A1 0137238 describes a casting system for continuous Strip casting of metals, especially a nozzle arrangement with an extruded nozzle holder and one fireproof, pre-cast nozzle. The nozzle holder is as one Extruded and shows all essential details and Tolerances. This nozzle holder and an additional fastening wedge consist of an extruded aluminum alloy. The pouring nozzle is attached to the holder with screws attached and for example with a fastening wedge clamped. This will remove and replace the Nozzle done in minimal time.

JP, A 01224144 has a slow and steady Flow of molten steel to the object, hence a Cast strand of good quality can be made. The molten metal introduced from a distribution trough directed into the interior of the fixed nozzle element. After Decreasing the flow rate occurs the melted Metal out of the nozzle gap 11. A movable nozzle element can with an actuator towards the fixed nozzle element or be moved away from it. That can the nozzle opening between the nozzle elements and thus the Flow rate of the molten steel set will. With this vertical continuous casting process Cast bars of good quality are made.

The inventors set themselves the task of a strip caster for metals of the type mentioned and a Process for their operation to create a pouring nozzle allow with always optimal positioning.

Calculations using computer models and tests have shown that productivity can be increased if the Distance of the nozzle from the roll gap is increased. This distance However, it must not be too big when starting up the strip caster because this would otherwise be due to premature solidification is overloaded or for the application of larger forces must be dimensioned. With most systems, the pouring nozzle is not or only under difficult, complex Restrict conditions during operation. A horizontally displaceable remedy, for example and height-adjustable pouring nozzle according to the mentioned EP, A1 0443 204. Each time the nozzle is withdrawn from the optimum In known systems, a gap arises through which after the surface tension has been exceeded Metal can flow.

The object is achieved according to the invention in relation to the strip caster solved by one or both of the nozzle elements adjustable at least in the area of the outlet opening is. Special and further training embodiments the strip caster are subject to dependent device claims.

Adjustable nozzle elements cause a retreat the gap between the nozzle lip and the roller is constant held and no metal can flow back.

The two side delimiters of the pouring nozzle are known per se Way designed so that the outlet opening the nozzle can expand when retracting without metal between flow out of a nozzle element and a side limiter can.

• Eines der beiden Düsenelemente ist starr an den Schmelzeverteilungstrog angelenkt, das andere kann parallel verschoben werden.
• Beide Düsenelemente können am Schmelzeverteilungstrog parallel verschoben werden.
• Ein Düsenelement ist starr am Schmelzeverteilungstrog angelenkt, das andere hat eine gelenkige Verbindung.
• Beide Düsenelemente haben eine gelenkige Verbindung zum Schmelzeverteilungstrog.
• Beide Düsenelemente sind starr am Schmelzeverteilungstrog angelenkt und haben in Richtung der Austrittsöffnung ein parallel zu ihr verlaufendes Gelenk.
• Beide Düsenelemente sind starr am Schmelzeverteilungstrog angelenkt, ein Düsenelement hat in Richtung der Austrittsöffnung ein zu ihr parallel verlaufendes Gelenk.

For example, the following variants result for the adjustment of the outlet opening:

• One of the two nozzle elements is rigidly articulated to the melt distribution trough, the other can be moved in parallel.
• Both nozzle elements can be moved in parallel on the melt distribution trough.
• One nozzle element is rigidly articulated on the melt distribution trough, the other has an articulated connection.
• Both nozzle elements have an articulated connection to the melt distribution trough.
• Both nozzle elements are rigidly articulated on the melt distribution trough and have a joint running parallel to them in the direction of the outlet opening.
• Both nozzle elements are rigidly articulated on the melt distribution trough, one nozzle element has a joint running parallel to it in the direction of the outlet opening.

Of course, with all variants with an adjustable The upper or lower nozzle element, left or right for vertical strip caster, be meant. There are some other possible combinations, for example, one that can be moved in parallel Nozzle element with a joint in the direction of the outlet opening. These combinations are caused by technical problems and considerations of economy are limited, whichever is the simplest and most solid variant best is.

A joint located directly on the melt distribution trough is preferably a hinge pivotable about an axis. A joint on a nozzle element is expediently one by one Axis swiveling hinge, a foil hinge, at Casting aluminum, especially spring steel, a molded one elastic block, especially from the same Fiber material such as the nozzle element, or a tensile fabric.

The nozzle elements can be built in a conventional manner viewed from the side essentially in the form of a Pen. At least one nozzle element is more suitable Site severed to form a joint and articulated with the remnant rigidly hinged to the melt distribution trough connected.

The invention can also be used to design to simplify the pouring nozzles. A plate-shaped Piece is rigidly connected to the melt distribution trough and has an articulated connection in the direction of the outlet opening to a much thinner plate, which in Cross-section long rectangular, but corresponding to rombus or can even be almost triangular.

As already mentioned, the very small distance is about 0.2 up to 0.5 mm of a nozzle lip to the corresponding roller constant to keep that neither scrap marks on the casting rolls still flowing through metal between the pouring nozzle and Casting roller can occur.

According to a variant of the invention are in the area of the nozzle lips Sliding inserts made of a self-lubricating material, in particular made of graphite or hexagonal boron nitride, built into the nozzle elements. This allows the nozzle elements regularly in exposed areas or across the entire width spread out without any Grinding marks arise. For more information, see the DE, A1 2131435. The sliding insert can also extend over the entire width of the nozzle.

Regarding the method of operating a strip caster The object is achieved in that the Pouring nozzle for starting with the outlet opening in a Starting position advanced and then into a working position is withdrawn, the outlet opening under Adaptation to the rotating mold is expanded.

When the pouring nozzle is withdrawn, the existing, albeit slight metallostatic pressure towards an expansion of the outlet opening. Preferably becomes horizontal or sloping during the retreat Pouring nozzle the metallostatic pressure increases, in particular by increasing the level in the melt distribution trough. In order to ensures that the moving part of the nozzle elements spread or shifted in parallel until the original distance from the casting rolls restored is.

The pivoting movement or the parallel displacement at least a nozzle element can also with the help or at least under Use mechanical force. Of the Drive can be by spring force, by a counterweight, by pneumatically, hydraulically or electrically generated force respectively.

The use of the casting nozzles according to the invention can, as at the beginning indicated, in all types of strip casting systems, for example Roll casting systems, casting systems with endless revolving Belts or caterpillar tracks are made.

Not only aluminum and Aluminum alloys, but also other metals like zinc, Lead, copper, iron and their alloys, including steel, are cast will.

The cast metal band always has a level line-free Surface, so no transverse channels.

For the manufacture of the nozzle elements are preferred Ceramic fibers used, which are impregnated with a slip, dried and burned. This creates a relatively brittle molded body which is fireproof, resists the liquid metal chemically and physically and has low thermal conductivity.

• Fig. 1. einen Längsschnitt durch eine zwischen rotierende Giesswalzen eingefahrene Giessdüse mit einem verstellbaren Düsenelement,
• Fig. 2 eine Variante von Fig. 1 mit zwei verstellbaren Düsenelementen,
• Fig. 3 einen Längsschnitt durch einen Schmelzeverteilungstrog mit angelenkter Giessdüse,
• Fig. 4 einen teilweisen Längsschnitt durch eine Giessdüse mit einem eingeformten Gelenk,
• Fig. 5 einen teilweisen Längsschnitt durch eine Giessdüse mit einem Gewebescharnier,
• Fig. 6 einen Längsschnitt durch den Bereich einer Düsenlippe mit selbstschmierender Einlage,
• Fig. 7 ein oberes Düsenelement mit Folienscharnier und einer Feder, und
• Fig. 8 ein oberes Düsenelement mit Folienscharnier und einem Gegengewicht.

The invention is explained in more detail with reference to exemplary embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically:

• 1 shows a longitudinal section through a pouring nozzle retracted between rotating casting rolls with an adjustable nozzle element,
• 2 shows a variant of FIG. 1 with two adjustable nozzle elements,
• 3 shows a longitudinal section through a melt distribution trough with a hinged pouring nozzle,
• 4 shows a partial longitudinal section through a pouring nozzle with a molded-in joint,
• 5 shows a partial longitudinal section through a pouring nozzle with a fabric hinge,
• 6 shows a longitudinal section through the area of a nozzle lip with a self-lubricating insert,
• Fig. 7 is an upper nozzle element with a film hinge and a spring, and
• Fig. 8 shows an upper nozzle element with a film hinge and a counterweight.

The pouring nozzle 10 shown in FIG. 1, which is articulated to a melt distribution trough 12 (not shown) (FIG. 3), comprises an upper and a lower nozzle element 14, 16. The upper nozzle element 14 has an adjustable mouthpiece 18 and is parallel to one another Outlet opening 20 of the pouring nozzle 10 pivotable axis A _{2 of} a hinge 22 pivotable.

When starting, the pouring nozzle 10 is with the outlet opening 20 advanced to the starting position S shown in broken lines. The distance of the nozzle lips 24 from the top and the lower casting roll 26, 28 is in the range from 0.2 to 0.3 mm. The distance d of the nozzle opening 20 from the roll gap 30, the smallest distance between the casting rollers 26, 28 on the connecting plane E of which are outside the drawing sheet Axes, is in the range of 20 to 50 mm.

Immediately after starting, the pouring nozzle 10 is around the Distance a from about 30 to 70 mm in the working position W der Exit opening 20 withdrawn. When withdrawing, the Pouring nozzle 10, also program-controlled, to the depth t lowered, taking into account the not shown Roller radius and the distances a, d is calculated so that the distance of the nozzle lip 24 of the lower nozzle element 16 from the lower nozzle roll 28 unchanged at about 0.2 to 0.5 mm remains.

The mouthpiece 18 of the upper nozzle element is included in the following Figures set means shown in detail so that the same distance of the nozzle lip 24 from the top Nozzle element 16 is retained.

The pouring nozzle 10 thus adapts automatically when moving back to the roller and leaves relatively large adjustment options to. The distance d is set as small as it allows the construction of the nozzle, the distance a is so large that the machine is not overloaded or dimensioned larger have to be.

In FIG. 2, a variant of FIG. 1, the lower nozzle element 16 also has a mouthpiece 18 which can be pivoted via a hinge 22 with an axis A _2. When the pouring nozzle 10 is retracted from the starting position S into the working position W by the distance a the height of which is not adjusted, the lowering t of FIG. 1 is omitted. Both mouthpieces 18 are adjusted by means of pivoting about the axes A _2, which will be described in detail later, in such a way that the distance between the nozzle lips 24 and the casting rolls 26, 28 remains unchanged at approximately 0.2 to 0.3 mm.

3 shows a mobile pouring trough 32 according to EP, A1 0443204, which has a melt distribution trough 12 with a detachably articulated pouring nozzle 10 with respect to the direction of flow F of the molten metal 35, in the present case an aluminum alloy. The upper nozzle element 14 is articulated via a hinge 22 with an axis A ₁ , the lower nozzle element 16 rigidly to the melt distribution trough 12. Both nozzle elements 14, 16 are supported by a pivotable or rigid nozzle holder 34, 36, which can be removed with the pouring nozzle 10, a lowerable slide 38 closing the melt distribution trough 12.

The melt distribution trough 12 is through a partition 40 separated from the mobile launder 32 with an opening 42. This opening 42 is connected by means of a flap 44 a terminal, truncated cone-shaped pin 46 is program-controlled lockable. The pivoting movement of the flap 44 is indicated by an arrow 48. The metal level 50 in Melt distribution trough 12 is due to the immersion depth of the Pin 46 adjustable in the opening 40, but it lies in any case below the metal level 52 in the mobile Watering channel 32.

Both the mobile trough 32 and the melt distribution trough 28 are with a refractory insulation layer 54 lined. At 56 is a drain for the liquid Metal 35 indicated.

For the height adjustment, the feed and the retraction of the Casting nozzle 10 is expressly referred to EP, A1 0443204 (US 5176198), in particular reference to FIG. 5 and its description, which for understanding the horizontally movable and height-adjustable pouring nozzle 10 integrating Is part of.

The metal level 52 of the mobile launder 32 and the metal level 50 of the melt distribution trough 12 are, for the sake of simplicity not shown floats or non-contact working sensors checked and adjusted. Both methods are known per se. The generated signals are proportional to the height of the swimmer or the distance between sensor and metal surface. These signals are refurbished and become a processor or computer transmitted where the actuation of actuators is triggered which is the metal supply according to the measured Control metal levels 50, 52. Such an actuator is for example the flap 44. When the pouring nozzle is withdrawn 10, the metallostatic pressure can be increased by increasing the Metal levels 50 increased and the outlet opening 20 enlarged without any additional aids.

4 shows a variant of an upper nozzle element 14 shown with an adjustable mouthpiece 18. The nozzle elements 14, 16 consist for example of impregnated with slip Ceramic fibers, which are dried and burned and so all chemical and physical requirements to the pouring nozzle. In the upper nozzle element 14 are the ceramic fibers across the entire width of the pouring nozzle not over a length l of, for example, 20 to 30 mm Slip has been soaked. So they stay while burning flexible and does not become brittle like the rest of the Nozzle element 14. This molded-in elastic block allows an adjustment of the outlet opening 20 by pivoting the mouthpiece 18 of the upper nozzle element 14.

Thanks to the high surface tension of the molten Metal 35 can also do this in the area of the elastic block 58 do not penetrate the ceramic fibers.

5 shows an upper and a lower nozzle element 14, 16 and the corresponding mouthpieces forming the nozzle opening 20 18, which has an internal tissue or Foil hinge 60 are connected. A fabric hinge is flexible in terms of bending, but leaves no elongation in the longitudinal direction too. It consists of temperature and tensile fibers that cannot be oxidized, for example made of fiberfrax. Especially when casting of aluminum or aluminum alloys can also be a Foil hinge made of a metal, for example spring steel, be used. A fabric or foil hinge 60 can be arranged inside or outside.

It is also shown that a nozzle is not in accordance with the invention only from conventional nozzle shapes with one or two cut off Mouthpieces, but also from simple molded parts can consist, for example, of a thicker and a thinner plate of rectangular cross-section. The embodiment 5 shows in the direction of the outlet opening 20 bevelled nozzle elements 14, 16 and over the Full length linear tapered mouthpieces 18.

6 shows the area of the nozzle lip of an upper nozzle element 14. In the area of the nozzle lip 24 are regular Distances across the entire width of the upper nozzle element several inserts 62 made of a self-lubricating material, in the present case, graphite. These deposits 62 are about 0.2 to 0.3 mm from the nozzle lip and can thus make any contact of the Avoid nozzle 10 with a casting roller 26, 28 (Fig. 1, 2).

Of course, inserts 62 can also be placed in mouthpieces 18 and can be inserted into a lower casting element 16.

7, 8 show means for adjusting the mouthpieces 18 an upper nozzle element 14. Of course can also the lower nozzle element 16 a correspondingly adjustable Have mouthpiece 18, but this is usually the case here not necessary because the weight of the mouthpiece 18 automatically swings down. In all cases can, as already mentioned above, the metallostatic Pressure instead of mechanical means or these complete.

7 is with a fabric or foil hinge 60 connecting upper nozzle element 14 and mouthpiece 18 each Angle piece 64, 66 attached, overall - according to the Width of the pouring nozzle 10 - at least two. The flow direction F of the molten metal lying one behind the other Brackets 64, 66 are connected to one another via a spring 68. This is slightly tensioned in the approach position S (Fig. 1, 2), when moving the pouring nozzle 10 back into the working position W becomes the mouthpiece 18 corresponding to the casting roll 26 raised.

In the embodiment according to FIG. 8, only the mouthpiece is left 18 an elbow 66. There is one in the direction of flow F of the molten metal threaded rod 70 attached, which is slidable by turning Counterweight 72 carries, the function of the spring 68 according Fig. 7 corresponds.

According to other variants, not shown, are about with the elbow 66 articulated cylinder and others Rods adjustable forces, which of the above mentioned pneumatic, hydraulic and electromotive Means can be generated programmatically and one define exact path.

All figures are drawn for horizontal strip casting, however, they are also suitable for oblique strip casting up or down, Fig. 3 and 8 only for small deviations from the horizontal. 1, 2 and 4 to 7 um Vertical band casting is also shown rotated 90 °.

Claims (10)

1. Strip casting plant for metals, in particular for aluminium and aluminium alloys, with a casting nozzle (10) displaceable in direction of flow (F) of the liquid metal (35) and adjustable perpendicular to this, to supply liquid metal (35) to the adjustable roller gap (30) between rotating dies (26, 28), where the casting nozzle (10) consists of two nozzle elements (14, 16) attached to a melt distribution trough (12) and two side limiters which form a slot-like outlet opening (20) for the liquid metal (35),
   characterised in that
   one or both of the nozzle elements (14, 16) is adjustable at least in the area of the outlet opening (20).
2. Strip casting plant according to Claim 1, characterised in that at least one nozzle element (14, 16) of the casting nozzle (10), preferably supported by a nozzle holder (34), is mounted on melt distribution trough (12) to displace parallel to and/or swivel about an axis (A₁).
3. Strip casting plant according to Claim 1 or 2, characterised in that at least one nozzle element (14, 16) has an axis (A₂) parallel to the outlet opening (20) for swivelling of a mouthpiece (18).
4. Strip casting plant according to Claim 2 or 3, characterised in that on the melt distribution trough (12) is arranged a hinge (22) mounted to swivel about an axis (A₁) and/or on a nozzle element (14, 16) is arranged a hinge (22) mounted to swivel about an axis (A₂), a textile or strip hinge (60) or an inserted elastic block (58).
5. Strip casting plant according to one of Claims 1 to 4, characterised in that a nozzle element (14, 16) comprises a thicker plate rigidly mounted on the melt distribution trough (12) and a thinner mouthpiece plate (18) articulately connected, where both plates are essentially rectangular in cross section or bevelled.
6. Strip casting plant according to one of Claims 1 to 5, characterised in that in the area of nozzle lips (24), sliding inserts (62) of a self-lubricating material preferably graphite or hexagonal boron nitride, are integrated into nozzle elements (14, 16) or mouthpiece (18).
7. Strip casting plant according to one of Claims 1 to 6, characterised in that a tension spring (68) or for a horizontal strip casting plant a counterweight (72) is mounted on the rotatable mouthpiece (18) of a nozzle element (14, 16), where applicable via at least one angle piece (64, 66).
8. Strip casting plant according to one of Claims 1 to 6, characterised in that an adjustment device with servo control, preferably a spindle or linear guide with servomotor or piston rod with a pneumatic or hydraulic cylinder, acts on the swivelable mouthpiece (18) of a nozzle element (14, 16), where applicable via an angle piece (66).
9. Process for the operation of a strip casting plant according to one of Claims 1 to 8,
   characterised in that
   casting nozzle (10) is advanced at the start with the outlet opening (20) in the start position (S) and then withdrawn to work position (W), where the outlet opening (20) is expanded according to the rotating dies (26, 28).
10. Process according to Claim 9, characterised in that during withdrawal of an approximately horizontal casting nozzle (10), the metallostatic pressure is increased preferably by raising the level of the metal (50) in the melt distribution trough (12).

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