The present invention relates to novel nozzles for continuous casting of steel with
inside spiral design. More particularly this invention pertains to novel nozzles
employed for continuous casting of molten steel in combination with or without
tundish nozzles used in between tundish and mould to cast steel in continuous casting
shop of steel units, which carry either continuous or discontinuous spiral designs
extending either full length or part length of the said nozzles of this invention.
Conventional nozzles normally used are known as sub-entry nozzle (SEN), immersion
nozzle (IN) or sub-entry shroud (SES). Bore configuration of such conventional
nozzles are usually of cylindrical, flat or tapered shape as adopted by most of the
present day steel makers, as may be seen from the diagrams shown in Fig. 1 (a, b, c, d,
e) of the accompanying drawings. The outlet design may either have a single port or
multiple port design through which molten steel flows to mould. Flow velocity of
molten steel through the polished, smooth bore of conventional nozzles often tends to
be slow or even non-uniform while flowing into the mould. Low velocity causes drop
in temperature in the meniscus, often causing meniscus freezing resulting in defects in
steel.
Usually the operator controls the flow of steel with considerable care either through
stopper or through tundish slide gate mechanism.
Casting powder is used in the mould for providing lubrication effect in the mould.
Mould powder also acts an inclusion absorption and insulation which prevents heat
loss. Lowering of temperature and uneven temperature distribution leads to partial
melting of mould powder creating problem in operation, such as freezing effect of
steel and increase of inclusion in steel which at times leads to "break out" due to
sticking of steel to refractory body or mould wall.
As mentioned hereinabove, nozzles are used for casting of steel from tundish to mould
in combination with or without tundish nozzle (TN), employed between tundish and
mould to cast steel in continuous casting shop of steel units. Rate of steel through
nozzles to mould has profound impact on steel quality, depending on a number of

parameters in the mould such as, for instance, intensity of turbulence, meniscus
velocity, temperature distribution, rate of melting of mould powder, etc.
Quality of steel depends on the variable factors above mentioned, the one exerting
most influence is proper maintenance of temperature distribution/temperature gradient
in the course of passage of molten steel through the nozzle onto the mould. Uneven
temperature distribution or lowering of temperature will not be able to melt the mould
powder to the desired extent, as a result of which unmelted mould powder will
adversely affect surface characteristics of cast steel, not to speak of lack of desirable
lubrication effect.
The present invention aims at overcoming the drawbacks of the conventional sub-
entry or immersion nozzle or sub-entry shroud nozzle and provide a novel type of
nozzle which are provided with spiral design(s) in the inside surface thereof.
The principal object of this invention is to provide a novel nozzle with inside spiral
design to ensure unhindered production of steel castings of excellent quality.
A further object of this invention is to provide a novel nozzle with bore configuration
of continuous or discontinuous spirals to allow a churning effect to be created in the
mould through which molten steel comes out of the product outlet having a single or
multiple port configurations.
A still further object of this invention is to provide a novel nozzle with inside spiral
design capable of creating optimum turbulence and ensuring uniform heat distribution
in the mould.
Another object of this invention is to provide a novel nozzle which ensures uniform
melting of casting powder in the mould and performs a full or partial function of
"electromagnetic stirring" (EMS) effect.
Yet another object of this invention is to provide a novel nozzle which ensures an
optimum temperature distribution in the mould thereby bringing about uniform
melting of mould powder in the mould to give a good lubrication effect to maintain a
smooth, unhindered flow of molten steel.

The foregoing objects are fulfilled by the present invention which relates to novel
nozzles for continuous casting of steel with inside spiral design, characterized in that
inside the said nozzle there is provided design of spiral grooves selected from single
spiral or multi spiral, which may have continuous grooves or discontinuous grooves as
shown in Fig. 2 (a, b, c, d) of the accompanying drawings, respectively.
The novel nozzles of this invention are made from alumina-zirconia-magnesia-spinel-
graphite/carbon composite material compacted in iso-static press, optimally
employing rubber mould and steel pin, followed by firing under a reducing
atmosphere to achieve the desired characteristics. This can also be made in a hydraulic
or mechanical press, by using steel mould in place of rubber mould.
Following firing, the products are brought to ambient, machined and then a coating of
anti-oxidizing and heat-resistant paint is applied on the surface as well as to the bore
wall to prevent carbon present in the constituent composite material from being
oxidized in the course of use, particularly in the extreme harsh conditions at molten
steel temperature.
The unique spiral designs are imparted inside the bore of the nozzle from bottom to
top, covering either the entire or part length of the product vertically, irrespective of
the length of the said nozzle.
The width of spiral grooves varies between 1 and 50 mm, optimally 10 to 20 mm,
depending on the bore diameter and depth of the grooves varies between 2 and 50
mm, preferably 5 to 10 mm, depending on the wall thickness of the said nozzle. Spiral
pitch is minimum of 30 mm, which may extend to the full length of the nozzle.
The bore wall of the aforesaid nozzle has a plurality of ports for ensuring rapid
outflow of molten steel and may also be provided with arrangement for argon
injection by means of a suitable device in order to maintain an inert atmosphere.
As mentioned hereinabove, the novel nozzles of this invention are made from
alumina-zirconia-magnesia-spinel-graphite/carbon composite material in a compacted
state. After firing in a reducing environment and machining, an anti-oxidizing paint is

applied both on the external surface as well as in the internal walls and spiral
structures made therein so that carbonaceous materials are not easily attacked in the
harsh surrounding of operation, while allowing molten steel to pass through for being
led into moulds. This enhances working life of the nozzles of the present invention. If
intended or considered necessary, provision for argon injection may be provided.
Spiral design grooves are made by a special technique inside the bore from one end to
another, either covering the entire length or a part thereof vertically, irrespective of the
length of the product. The inside spiral design resembles a snake crawling in the field.
When steel flows through the novel nozzle of this invention, a turbulence and
churning effect is created in the mould through which molten steel comes out of the
product outlet, which may have a single or multiple ports, configuration of which may
be round, oval, square, rectangular or any such geometrical shape. This creates an
optimum turbulence and brings about uniform heat distribution in the mould, which in
turn ensures uniform melting of casting/mould powder in the mould and brings about
a partial or full function of electromagnetic stirring (EMS) effect, simultaneously
producing a good lubrication effect on account of such uniform melting of casting
powder in a suiting to the temperature environment in the mould.
The invention will now be further amplified by means of the illustrative drawings
accompanying this specification wherein.
Fig 1 (a, b, c, d, e) : shows the front sectional views of a few normal nozzles at
present in use having cylindrical/flat bore;
Fig. 2 (a, b, c, d) shows front cross-sectional views of a few representative
nozzles with spiral designs, both continuous and partial or
discontinuous varieties, the latter usually covering the lower
Fig. 4 (a, b, c) region;
Fig. 4(d) shows a sectional view of the novel nozzle with continuous
spiral design along section A-A and also a view from B-B;
Fig. 5(a) represents 'velocity vector' for single port normal nozzle, which

shows the velocity to be 0.1 - 0.25m/sec. at the meniscus. This
is less than optimum velocity and may result in non-melting of
mould powder, thereby increasing inclusion in steel and
affecting product quality;
Fig. 5(b) depicts 'velocity vector' for nozzle with inside spiral design.
Velocity is found to be 0.2 - 0.5 m/s, which is optimum for
proper melting of mould powder. This substantially reduces
inclusion in steel, even if there is no EMS;
Fig. 6(a) shows temperature contour of single port conventional nozzle.
Temperature is shown to be around 600°C, which is not
sufficient for proper melting of mould powder and this is likely
to increase inclusion in steel; and
Fig. 6(b) exhibits temperature contour of nozzle with inside spiral design,
from which it may be observed that temperature at meniscus is
around 900°C. This helps to melt the mould powder properly
and substantially reduces inclusion in steel, even if there is no
EMS.
The results shown in Figs. 5 and 6 of the drawings have been generated by monitoring
mould conditions with the help of mathematical modeling using Ansys Fluent CFD
software. Both Figs. 5 and 6 establish that novel nozzles with spiral design inside, be
it continuous or discontinuous, are capable of establishing the efficacy of these
products which lead to production of good quality moulded products.
The exterior contours, particularly at the upper end thereof, may vary. Usually they
taper downward, having a fluted mouth with slight exterior protrusion of Tip', to
prevent spillage of molten metal.
Apart from the composite material, the nozzles of this invention may be fabricated
from alumina, aluminosilicates, slay, carbon, graphite, magnesia, magnesite (fused,
deadburnt or/and sintered), zirconia, zircon or composites of Al-Mag/Mag-Al spinel
by suitably combining any two or more of the aforesaid materials followed by after
treatment as narrated above.
Although the preferred embodiment of the present invention has been disclosed for
illustrative purposes, those skilled in the art will appreciate that various modifications,
additions and substitutions are possible, without deviating or departing from the scope
and spirit of the invention as recited in the claims appended hereafter.

We claim:
1. Novel nozzles for continuous casting of steel with inside spiral design,
characterized in that inside the said nozzle there is provided design of spiral
grooves selected from single spiral or multi spiral, which may have continuous
grooves or discontinuous grooves as shown in Figs. 2, 3 and 4 of the
accompanying drawings, respectively.
2. Novel nozzles as claimed in Claim 1, characterized in that these products are made
from alumina-zirconia-magnesia-spinel-graphite/carbon composite material
compacted in iso-static press, optimally employing rubber mould and steel pin,
followed by firing under a reducing atmosphere to achieve the desired
characteristics, alternatively, by employing hydraulic or/and mechanical press and
using steel moulds in lieu of rubber moulds.
3. Novel nozzles as claimed in Claims 1 and 2, characterized in that following firing
of the products these are brought to ambient and a coating of anti-oxidizing and
heat resistant paint is applied on the surface as well as to the bore wall to prevent
carbon in the constituent composite material from being oxidized in the course of
use, particularly in the extreme harsh conditions.
4. Novel nozzles as claimed in Claims 1 and 2, characterized in that spiral designs are
imparted inside the bore of the nozzle from one end to another, covering either the
entire or part length of the product vertically, irrespective of the length of the said
nozzle.
5. Novel nozzles as claimed in Claims 1 to 4, characterized in that width of spiral
grooves varies between 1 and 50 mm, optimally 10 to 20 mm, depending on the
bore diameter, and depth of the grooves varies between 2 and 50 mm, preferably 5
to 10 mm, depending on the wall thickness of the said nozzle and pitch of the
spiral is minimum 30 mm extending up to the full length of the nozzle.
6. Novel nozzles as claimed in Claims 1 to 5, characterized in that the bore wall of
said nozzle has a plurality of ports for ensuring rapid outflow of molten steel and
may also be provided with arrangement for argon injection by suitable device in
order to maintain an inert atmosphere.
7. Novel nozzles for continuous casting of steel with inside spiral design,
substantially as hereinbefore described, with particular reference to the
accompanying drawings.

ABSTRACT

Conventional nozzles used for allowing passage of molten steel through the
nozzles onto the mould suffered from frequent uneven temperature distribution or
lowering of temperature which resulted in uneven melting of mould powder or
melting of mould powder to the desired extent. This resulted in affecting surface
characteristics of cast steel, not to speak of lack of desirable lubrication effect.
The present invention aims at overcoming the drawbacks the conventional
nozzles and provides novel nozzles for continuous casting of steel with inside spiral
design, characterized in that inside the said nozzle there is provided design of spiral
grooves selected from single spiral or multi spiral, which may have continuous
grooves or discontinuous grooves as shown in Figs. 2, 3 and 4 of the accompanying
drawings, respectively.