Note: Descriptions are shown in the official language in which they were submitted.
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Method and Device for Casting and Solidifying Liquid Metal
and Fragmenting Said Metal
The present invention relates to a method and a device for casting and
solidifying liquid metal, in
particular ferro-alloys or non-ferrous metals, and for fragmenting said
metals.
There is a need for a rapid and flexible method, and a corresponding device,
for casting and
solidifying liquid metals, in particular ferro-alloys and non-ferrous metals,
and for their
systematic fragmentation, with the aim of producing pellet-type products with
definable
dimensions, with minimal losses and impurities, as well as with a reduced
outlay for energy and
lower costs.
In the prior art, once they have been tapped from the oven in the liquid
state, iron alloys or non-
ferrous metals are usually cast in sand beds, and after they have solidified
and cooled they are
routed to a fragmenter, in which they are broken up and then graded into
commercial grain sizes
and packed.
In a first known method (Method 1 ), undersize particles, the quantity of
which can amount to
25%, are returned to the oven and melted down. This Method 1 entails the
following short-
comings and disadvantages:
1. High energy, production, and maintenance costs with respect to the
fragmenter and the
screening machinery:
2. A low product yield because of a comparatively high proportion of undersize
particles;
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3. The large quantities of dust and noise is that are generated require a
correspondingly
large investment and significant resources for dust and noise control;
4. A considerable proportion of the impurities in the product is caused by the
sand used in
the casting bed.
5. Complicated logistics;
6. The high cost of the product caused by the additional smelting of the
screened,
undersized particles.
A further known method ( Method 2) makes provision such that liquid metal is
cast in bars by
using a casting wheel, so that it can subsequently be reduced to the required
grain size by
crushing and screening. This Method 2 entails the following shortcomings and
disadvantages:
1. The shortcomings and disadvantages set out in Points 1, 2, 3, 5, and 6
listed with respect
to Method 1 also apply to Method 2, albeit to a lesser extent;
2. The throughput achieved by a casting wheel is restricted and inflexible,
and this requires
a longer casting time and, because of this, a higher tapping temperature, and
these result
in additional energy and refractory costs, or short availability times for the
furnace;
3. High costs are caused by a ladle economy;
4. It is possible to affect the dimensions of pellets of the product only by
adjusting the
screening machinery; this cannot be done during the casting process.
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US 4, 316,496 and the corresponding DE-OS 30 28 247 describe device and a
method for
generating a ferrous feedstock that is subsequently used in a smelting
crucible or a smelting
furnace.
In cross section, the device has an elongate channel-shaped substrate that is
supported so as to be
S movable in the horizontal direction, and which continuously moves past a
casting station, there
being means provided on this to continuously pour molten ferrous metal onto
the substrate so as
to produce a solidified iron strip after it has cooled. Means are also
provided to divide the
solidified strip into segments, whose size makes them suitable for use as
ferrous feed stock. The
substrate should be of a thickness that is sufficient to extract heat from the
strip that has been
cast, so as to promote solidification of the strip.
The surface of the substrate is provided with a row of projections that are
spaced equidistantly
apart. It is also possible to provide a roller, the surface of which
incorporates depressions, and
which is arranged above the beam, downstream from the casting station. This
roller is installed
at a distance from the surface of the metal that is sufficient to keep the
roller in contact with the
strip that has been cast and to emboss depressions into this when the strip
solidifies.
In the method used to produce a ferrous feedstock that is subsequently routed
to a smelting
furnace, the continuously cast iron material is cast from a casting station
onto a channel shaped
substrate and is moved continuously past the casting station in order to form
a solidified metal
strip; the solidified strip is separated from the substrate and-in the
solidified state-is divided
into segments of a size that makes them suitable for the required feed stock.
Proceeding from the prior art described heretofore, it is the objective of the
present invention to
propose a method and a device that corrects the above cited shortcomings and
difficulties.
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This objective has been achieved with a method for producing metal pieces, in
particular from
ferro-alloys or non-ferrous metals, from the liquid phase as in Claim 1, by
using a strip casting
plant that produces an endless strip of predeterminable thickness, as well as
a fragmenter that
breaks the strip into pieces; a pattern of predetermined breaking points being
impressed in the
surface of the strip during casting and solidification, said pattern ensuring
the predetermined,
optimal size of the pieces of product when the strip is fragmented.
One configuration of the method according to the present invention provides
that the pattern of
the predetermined breaking points is produced, for example, by welding profile
elements onto an
embossing roller.
When this is done, it can be advantageous to exploit the fact that the pattern
of predetermined
breaking points is produced by elements that are of a material that has
physical characteristics
that differ from those of the material of the embossing roller, e.g., greater
thermal conductivity.
In addition, the method according to the present invention is characterized in
that the casting
speed (Vg) as well as the position and distance of the embossing roller with
the pattern that is to
be produced is controlled by a regulating system as a function of the
properties of the product
that is to be cast, its tapping temperature, and the desired thickness (d),
and the diameter (D) of
the roller with the embossing pattern, according to the formula set out in
Claim 4.
It is also an advantage that the embossing roller with the embossing pattern
be cooled.
It is advantageous that a method for controlling the production method used
for metal pieces, in
particular those of ferro-alloys or non-ferrous metals, from the liquid phase,
which includes the
use of a strip casting plant for producing an endless strip of a predetermined
thickness, as well as
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a fragmenter for breaking the strip into pieces of predetermined dimensions,
acquires the metal
temperature and casting speed through sensors, the data so acquired being
routed to a control
system, e.g., a computer, for further processing, as a result of which the
position, speed of
rotation, and the depth of penetration of the embossing rollers) is adjusted.
A device for manufacturing metal pieces from the liquid phase, in particular
from ferro-alloys or
non-ferrous metals, by the method according to the present invention, includes
a strip casting
plant for producing a metal strip of predetermined thickness, and a fragmenter
that breaks the
strip into pieces, in which, in the case, for example, of a single belt strip
casting plant, there are
additional rollers for embossing a pattern of predetermined breaking points
during the casting
and solidification of the strip.
Other versions of the device according to the present invention are set out in
the secondary
claims.
Details, features, and advantages of the present invention are set out in the
following description
of an exemplary embodiment that is shown in the drawings appended hereto.
These drawings
show the following:
Figure 1: A side view of the device according to the present invention;
Figure 2: A section of the embossing roller of the device as in Figure 1, in
cross section (2a)
and in plan view (2b);
Figure 3 A plan view of a pattern of embossing elements applied to the
embossing roller.
S
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The device shown in Figure 1, as viewed from the side, that produces metal
pieces 5 of defined
dimensions from a continuously cast strip 3 from a strip casting plant (not
shown herein) moves
the strip 3 on an endless conveyor belt 6, which is preferably of metal, to
the embossing station
7
This embossing station has an upper embossing roller 1 that has embossing
elements 2 ( Figure
2) welded onto it and this embosses a pattern of predetermined breaking points
4 into the metal
strip that is passing below it before said strip has solidified.
A backup roller 1' rotates beneath the embossing roller 1 of the conveyor belt
6 so as to generate
the roller counterpressure that is necessary in order to complete the
embossing process.
In Figure 2a, the enlarged cross section taken on the line I-I shows the
embossing elements 2 that
protrude from the surface of the embossing roller 1 at the section line. The
associated plan view
shown in Figure 2b indicates their position in the form of a rectangular
pattern on the surface of
the roller.
Figure 3 is a plan view of the embossing roller l, in which the predetermined
breaking points 4
can be seen at the lighter points. When the embossed strip passes through the
fragmenter the
strip will break into fragments 5 that are of predetermined dimensions.
6
