Note: Descriptions are shown in the official language in which they were submitted.
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wo 02;24,379 A1 PCTlCH01100,573
STRIP-CASTING MACHINE FOR THE PRODUCTION OF A METAL STRIP
The invention pertains to a strip-casting machine for the
production of a metal strip with two adjacent casting rolls with
lateral surfaces of a certain width which form a casting gap
between them, the end surfaces of the rolls being provided with
side seals, the rolls being ratatably supported on a machine
stand and driven by at least one motor, where the metal melt is
supplied through at least one casting tube or the like to the
area between the casting rolls and the side seals, and is
protected by at least one gaseous medium.
In a strip-casting machine of the generic type in question
according tc the publication w0-A-97134,718, the horizontally
mounted casting rolls are supported in a machine frame, which
carries the rolls; a distribution vessel rests on the frame. To
seal off the surface of the metal bath, a plate is provided over
the bath, approximately parallel to its surface, which seals off
the two casting rolls. Underneath the casting rolls are separate
wall parts, which adjoin the machine frame, and a multipart box,
which is adjacent to the wall parts. The strip emerges from this
box. The disadvantage of this strip-casting machine is the
relatively complicated design used to seal off the metal bath
and/or the metal strip produced.
In another known twin-roll strip-casting machine according
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to the publication En-A-0 780 177, a box-like container is
provided to seal off the solidified metal strip emerging
underneath from the gap between the casting rolls. The walls of
this container extend all the way to the bottom parts of the
outer jackets of the casting rolls, where a seal is created by a
sealing element. This type of seal, however, is relatively
complicated in design and expensive to maintain and also entails
undesirable contact between the sealing element and the rotating
casting roll. When leaks occur, there is the danger that scale
can form on the metal strip, which lowers the quality of the
product.
Against this background, the present invention was based on
the task of creating a strip-casting machine of the generic type
indicated above, by means of which both the metal bath or the
produced metal strip and the casting rolls can be sealed off
satisfactorily from the ambient air and also so that the
operation and maintenance of the machine can be simplified.
The task is accomplished according to the invention in that
a preferably multipart housing encloses at least the lateral
surfaces and ends of the casting rolls and the side seals.
With this design of the strip-casting machine according to
the invention, it is easy to achieve an optimum seal for both the
metal bath present between the rolls and the metal strip emerging
underneath from between the casting rolls.
The casting rolls and the side seals, however, can
nevertheless be made accessible quickly and easily for the
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'. purpose of repair and maintenance, as a result of which the
output of the machine can be increased.
In a highly advantageous design, the housing for the metal
strip emerging underneath from the casting gap between the
casting rolls is adjoined by a longitudinal housing with a
chamber, where the chamber formed by the housing is connected by
an opening to the adjoining chamber of the longitudinal housing.
Exemplary embodiments of the invention and additional
advantages offered by it are explained in greater detail below on
the basis of the drawing:
-- Figure 1 shows a schematic longitudinal section through a
strip-casting machine according to the invention;
-- Figure 2 shows a cross section of a housing along the
axes of the casting rolls of a strip-casting machine according to
the invention;
-- Figure 3 shows a cross section through the housing
according to Figure 2; and
-- Figure 4 shows a schematic view of another variant of a
strip-casting machine.
Figure 1 shows a strip-casting machine 20 for the production
of a metal strip 15, especially a steel strip, which can be
produced in a continuous casting process. This strip-casting
machine 20 is mounted on a stage 12 and is supplied with metal
melt 16 from a distribution vessel 1$ installed above the
machine, as is known from conventional continuous casting
systems. It is advisable for the distribution vessel 18 to have
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-, a pouring opening 17; which can be closed by a stopper 19 or the
like, and a casting tube 13, extending to a point between the
casting rolls 22, 24, through which the melt can flow out.
The main components of this strip-casting machine 20 are the
two essentially parallel casting rolls 22, 24, the axes of which
are approximately horizontal. A side seal 25 is provided at each
end of the rolls, as a result of which an opening 26 is formed,
which is closed on all sides and which has the casting gap 15' at
the bottom. Each of the casting rolls 22, 24 is supported
rotatably at each end on a machine stand 32 and is driven by a
motor integrated into the stand.
According to the invention, the casting rolls 22, 24 are
surrounded by a closable housing 30, which has an opening 30' in
the top for the casting tube 13, which projects into the area
between the casting rolls 22, 24, and an opening 30" in the
bottom for the emerging metal strip 15. These openings 30', 30n
are sealed, and the chamber 33 inside the housing is filled with
a shielding gas, preferably an inert gas, during the casting
operation. In cases where two or more casting tubes are used, it
would be possible for several openings 30' to be provided in the
top. These openings could be round or slot-shaped, and there
does not necessarily have to be a casting tube in each one.
It is highly advantageous for this box-shaped housing 30 to
be a certain distance away from the sides and the top of the
casting rolls 22, 24 or from the machine stand 32, so that there
is no need for the sealing elements required in the case of the
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casting machine according to the previously cited publication EP-
A-0 780 177 to seal the metal melt off from the outside.
In the top, this housing 30 is provided with two horizontal
doors 35, which are designed so that they can be slid
horizontally from the closed position shown in Figure 1 into an
open position. For this purpose, they are guided laterally in
appropriate rails (not shown), and it is advantageous for them to
be lowered into the closed position shown so that the housing 30
can be sealed in the desired manner.
It would also be possible, however, to provide only one
door, which would in any case reduce the number of gaps to be
sealed. It would be advantageous for this one door to be
approximately equal in size to the two doors 35 shown and to be
provided with an appropriate opening 30' for the passage of melt.
In addition, the housing 30 is also provided with openings
39, which can be closed by doors 36. These openings make it
possible for the side seals 25 of the casting rolls 22, 24 to be
guided by manipulators 40, which are free to travel outside the
housing 30 and which are thus able to remove the side seals from
their operating positions shown and to take them out through
these openings 39 and return them to the housing 30 again. The
manipulator 40 in question has for this purpose a support arm 41
and a drive 42, which can adjust the height of the arm. The
manipulator can thus be moved from an operating position to a
retracted maintenance position and back again. In the operating
position of the manipulator 40, the unsealed opening 39 can be
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. sealed off by means of a separate shield enclosure 38. This
shield enclosure 38 surrounds the manipulator 40 and rests
tightly against the side of the housing 30. Cassettes 88 are
also indicated, which are used to bring the side seals up into
position and to carry them away.
Another advantage obtained within the scope of the invention
is that the cast metal strip 15 is guided underneath the housing
30 into an additional longitudinal housing 44, which forms a
chamber 45, in which a shielding gas is also present in order to
protect the metal strip 15 from contact with oxygen and
especially to prevent the formation of scale. In this chamber
44, several rollers 46 and compression rolls 47 are installed, so
that the metal strip 15 is guided through this longitudinal
housing 44 and through a sealed opening 48 in one end of the
housing. After it emerges from the housing 44, the metal strip,
which has cooled by this point, can be coiled up, for example, or
sent on for further processing.
In addition, the longitudinal housing 44 has a pit 49
underneath the opening 30" and thus underneath the casting gap
15'. A collecting tank 52 is provided in this pit in the plant
floor 51. This collecting tank 52 has the task of collecting any
liquid metal which might escape from between the casting rolls in
the event of a leak and thus of preventing any damage from
occurring. Above this tank 52 are also swinging guide flaps 54,
55, which form a pass-through opening in the position shown,
whereas in the pivoted position 54', 55' they form a guide path
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for the metal strip 15.
In the state of the casting operation illustrated in Figure
1, the top opening 30' in the housing 30 is sealed off by a
bellows 11 or the like, which connects the housing to the vessel
18. The sleeve-like bellows 11 surrounds the casting tube 13.
The casting tube could also be omitted and the melt simply
allowed to fall freely. The lower opening 30" in the housing,
through which the strip 15 passes, can be sealed off by a sealing
device in the form of a gas shield, for example, produced by
nozzles 34. In principle, however, this sealing device could
also be omitted, and the opening 30" thus could lead directly to
the chamber 45.
In addition, the housing 30 has a feed line (not shown) for
the injection of a shielding gas into the interior space 33.
Shielding gas can also be supplied to the distribution vessel 18,
which is provided with a cover. The gas introduced into the
housing 30 can be cooled and returned through a gas circuit.
Upon completion of the casting operation and before the housing
.is opened, the shielding gas can be pumped out and into a storage
tank, and the air in it can be filtered out if desired.
Figures 2 and 3 show the principle of a variant of a strip-
casting machine, which is designed basically in the same way as
the machine according to Figure 1. In this strip-casting
machine, a housing 60 is provided, which, according to the
invention, surrounds the casting rolls 22, 24. The multipart
housing 60 extends around both the lateral surfaces and the ends
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of the rolls and thus also encloses the side seals 62. The motor
stands 61 supporting the axles 64 of the casting rolls 22, 24,
however, are not enclosed. The housing 60 surrounds the axles at
both ends of the casting rolls and also the drive 66 of the seals
62. At the top, it is a certain distance away from the indicated
melt distribution vessel 18.
The multipart housing 60 is provided with a base 67 where it
meets the longitudinal housing 65; the base can be attached by
fastening elements 69 to the longitudinal housing.
Between the housing 60 and the longitudinal housing 65, an
opening 70 is present, which connects these two housings 60, 65
to each other. The longitudinal housing 65 is advantageously
sealed all the way around and has only one sealed outlet for the
cast metal strip 15.
Figure 4 shows a strip-casting machine according to the
invention, again with two casting rolls 22, 24, which are
contained in a housing 80. This housing 80 consists of double
side walls 81 and a cover 82, which is supported so that it can
be lifted off, as indicated by the cover 82', which has been
removed.
Within the scope of the invention, the housing 80 surrounds
the casting rolls 22, 24 and the side seals 83. In addition, the
housing has an opening 84 at the bottom, which communicates with
the chamber 85' of a longitudinal housing 85. The housing 80 is
positioned in a frame stand 88, which has wheels 87, which are
guided on rails 89.
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It is advantageous, furthermore, for both the housing 80 and
the longitudinal housing 85 to be water-cooled, so that their
temperature does not increase excessively during continuous
operation.
With this strip-casting machine according to Figure 4, a
design which is independent of format has been created, because
the housing can be made larger or smaller, depending on the
diameter of the casting rolls.
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