FIELD OF THE INVENTION
[1] This invention relates to the alignment of submerged entry nozzle (SEN), and more
particularly to alignment mechanism for centering a submerged entry nozzle which can
accurately measure and manage the centering position of SEN. Mechanism presented
hereby describes a SEN aligning apparatus which can be used to align SEN of any shape
and size accurately and precisely for smooth flow of molten metal from the tundish to the
mold. The present invention comprises of a laser based mechanism which helps align the
SEN quickly and precisely in order to minimise the occurrence of possible flow asymmetry
inside the mold during casting. Present invention is especially beneficial in continuous
casting settings with irregularly shaped SENs which are cylindrical near the tundish and
gradually elongate along one of the sides while simultaneously shortening on the other.
BACKGROUND OF THE INVENTION
[2] A continuous casting process typically involves transfer of molten metal from a ladle
1 to tundish 2 from which the metal is poured into the mold 3 through the SEN 4 which
is a kind of ceramic or composite tube installed between a reservoir of molten metal
(tundish) 2 and the mold 4. The molten metal flows through the SEN 4 into the mold 3
and then partially solidifies into the slab and is withdrawn by means of continuously
guided rollers while water spray system cools it as depicted in Figure 1.
[3] Misaligned SEN 4 while casting can lead to quality issues and potential breakouts,
especially in thin slab casters due to the small spaces between the SEN 4 and mold 3.
SEN 4 misalignment can cause the impingement of hot liquid metal with high momentum
against the solidifying shell which leads to large surface fluctuation as well as shell
thinning and possibly breakout. The misaligned SEN 4 will cause severe variation in
turbulence intensity at the meniscus. In the high turbulence regions which are created,
chances of slag or mold flux entrainment inside the mold will be high. These entrainments
in the steel can generate surface defects and surface cracks resulting in product rejection
and loss of manufacturing efficiency.

[4] Accurate alignment of SEN 4 plays a vital role in improving the quality of the casting
produced and preventing instances such as breakouts which lead to losses and potential
safety hazards. Accurate SEN 4 positioning helps to evenly distribute heat for uniform
shell growth, obtain steady flow conditions and also improve mold fluid flow behaviour.
Further, structure and positioning of SEN is very crucial in continuous casting process
because it optimizes the turbulence intensity and helps in achieving uniform solidification,
which is a key factor for producing cleaner and defect free product.
[5] The current practices generally involve use of mechanical methods such as thread-
weight alignment technique, scale or measuring tape based alignment system, etc. These
methods are manual with low accuracy and high chances of error. Further the
measurement is affected by atmospheric factors such as wind, etc. and distances are
measured through scale or measuring tape primarily by visual inspection. Such
measurements differ from person to person and lack consistency. Further there is no
provision for checking the accuracy of measurements during installation in the mold 3.
[6] Present mechanism solves this problem by carefully aligning the SEN 4 to the centre
of the tundish 2. It ensures that the SEN 4 is installed at the centre of the tundish hole 6
at an angle of 90 degrees to the base of the tundish 2. Further the mechanism to align
the SEN 4 at the exact centre of the mold 3 has also been proposed. The solution gives
accurate positioning of SEN 4 thereby ensuring smooth flow patterns maintaining the
quality of casting and avoiding casting related defects such as mold powder entrainment
and reverse flow circulations.
OBJECTS OF THE INVENTION
An object of the present invention is to evolve a mechanism for centering submerged
entry nozzle during continuous casting which ensures the centering and alignment of
submerged entry nozzle accurately in the tundish.

Another object of the invention is to evolve a mechanism for centering submerged entry
nozzle during continuous casting which control smooth flow of molten metal from the
tundish to the mold.
A further object of the invention is to evolve a mechanism for centering submerged entry
nozzle during continuous casting which helps to align the submerged entry nozzle (SEN)
quickly and precisely in order to minimize the occurrence of possible flow asymmetry
inside the mold during casting.
SUMMARY OF THE INVENTION
[7] The present mechanism is proposed using a two-step solution- first step involves
accurate alignment of SEN to the tundish which primarily takes place in the tundish
preparation area while the next step involves accurate positioning of the SEN to the centre
of the mold in the casting area.
[8]In the tundish preparation area, a laser based system can be used which is highly
accurate. A laser beam generation unit 20 can be mounted on top of the tundish 2
through an appropriate fixture such that the point laser beam 10 points directly downward
at an angle of 90 degrees to the floor of the tundish 2. Further the fixture needs to be
created in such a way that it ensures the point laser beam 10 is exactly at the centre of
the tundish hole 6 in which the SEN 4 is mounted. The accurate positioning of the SEN 4
can now be done in two different ways depending on the shape of the SEN 4. If the SEN
4 has an opening at the bottom concentric to the opening at the top then a laser
generation unit 20 which casts a point laser beam 10 can be mounted.
If the SEN 4 lacks an opening at the bottom then multiple optical illuminators 29 can be
used to project laser beams which serve to align the SEN 4 perpendicular to the base of
the tundish 2. These optical illuminators 29 can also serve as an additional aid for
alignment if the SEN 4 has an opening at the bottom concentric to the opening at the
top.

In the tundish operation area, a precise laser based system can be used which can
calculate the deviations of the SEN 4 from the center of the mold 3 and indicate these to
the operator for making the necessary corrections. A setup which uses laser based
distance measurement systems 31 for measuring the distances has been designed. The
system has also been integrated with software on the PC 34 to display graphical output
for monitoring the process.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 is a brief description of the continuous casting setup with a magnified view of
the top of the mold.
Figure 2 is a cross sectional view illustrating examples of correct and incorrect positioning
of SEN that is inserted into the mold
Figure 3 shows the results of fluid flow characteristics illustrated using water modelling
experimentation for correct and incorrect positioning of SEN that is inserted into the mold
Figure 4 is a block diagram illustrating a method of using an apparatus for centering a
submerged entry nozzle according to the present invention.
Figure 5 shows a configuration of a preferred embodiment in perspective view of the
apparatus for centering a submerged entry nozzle according to the present invention.
Figure 6a, 6b, 6c and 6d show different views of an apparatus used for aligning the
submerged entry nozzle according to the present invention.
Figure 7a and 7b shows another apparatus used for aligning the submerged entry nozzle
according to the present invention.
Figure 8 shows a configuration of a preferred embodiment in perspective view of the
apparatus for centering a submerged entry nozzle according to the present invention.

Figure 9 is a perspective view of a configuration of another preferred embodiment of the
apparatus used for centering a submerged entry nozzle according to the present
invention.
Figure 10 is a perspective view of a configuration of preferred embodiment of the
apparatus used for centering a submerged entry nozzle at the center of the mold in the
casting area according to the present invention.
Figure 11 is a block diagram illustrating a method of using an apparatus for centering a
submerged entry nozzle in the casting area according to the present invention.
DETAIL DESCRIPTION OF PREFFERED EMBODIMENT
[9] Figure 2 is a cross sectional view illustrating examples of correct and incorrect
positioning of SEN 4 that is inserted into the mold 3. Figure 2a, 2b & 2c are front views
of the mold 3 with Figure 2b showing the correct SEN 4 positioning while Figure 2a & 2c
show SEN 4 deviations to the left and right respectively.
Figure 2d, 2e and 2f are the top views of the mold 3 with Figure 2e showing the correct
SEN positioning while Figure 2d & 2f show SEN deviations to the back and front
respectively.
Figure 3 shows the results of water modelling experimentation illustrating the fluid flow
symmetry and asymmetry characteristics in relation to correct and incorrect positioning
of SEN that is inserted into the mold. Figure 3a shows the perfectly symmetric flow in
case of correctly aligned SEN 4 to the center of the mold 3 while Figure 3b & 3c shows
the asymmetric flow with SEN 4 deviated to the right and left respectively.
When the SEN 4 is accurately centered, a left-right symmetry flow pattern is formed
inside the mold 3 which ensures smooth quiescent meniscus and consistent initial
solidification, such that it is possible to manufacture a defect free slab.
The procedure for installing the SEN 4 in the desired position with correct orientation is
briefly described here after. Embodiment of an apparatus for accurately installing the SEN

4 into the tundish 2 is described in detail with the accompanying drawings. Figure 5 shows
a perspective view of an apparatus 9 mounted on the tundish 2 in the SEN 4 installation
area. The apparatus 9 has been constructed in a manner that it can be easily transported
from one place to another and is operational in high temperature, dusty environments.
Figure 5 shows a tundish 2 mounted on a tundish stand 5 with the apparatus9 installed
on it. The apparatus 9 consists of a mechanical assembly 7 for accurate alignment of a
laser beam projection unit 20 firmly mounted on the tundish hole6 by means of a
placement device8.
[10] Figure 6a & 6c show two different views of the mechanical assembly 7. The internal
details of views shown in Figure 6a & 6c are shown in Figure 6b & 6d. Referring to Figure
6(b), the mechanical assembly 7 for alignment of laser beam projection unit 20 includes
housing 17, a laser beam projection unit 20, a laser installation mount 16 and a protective
cover 15 to safeguard the laser beam projection unit 20. The housing 17 is typically an
enclosure or covering which safeguards the laser beam projection unit 20 and other
internal accessories from external damages. The bottom part of housing 17 is a disc
structure 21 with appropriate fixtures 19 to attach it firmly and accurately to the
placement device 8. Inside the housing 17 is a laser beam projection unit 20 mounted on
a laser installation mount 16 which serves to detach the laser beam projection unit 20 in
cases of repairs. The laser installation mount 16 also features dust protection system to
safeguard the laser beam projection unit 20 from dust and other particles which may
erode from the vessel surfaces. Additionally, in case of higher working temperatures a
water jacket may be installed inside the mount 16 to safeguard the lens. The switch 18
on top of the system helps control the power input to the laser beam projection unit 20.
The laser beam projection unit 20 may be powered with batteries or DC power supply as
per convenience.

[11] The placement device 8 as shown in Figure 7 consists of a tubular structure 22
preferably made of metal with a variable internal cross-section which gradually decreases
as we go downwards. The circular hole 23 at the bottom of the tubular structure 22 has
a very small diameter nearly equal to that of the error margin of the laser if it is very high
or to the suitable manufacturing limit which further ensures that point laser beam 10 will
always pass through the centre of the device.
[12] Referring to Figure 7, the placement device 8 is designed such that the outer
diameter of the tubular structure 22 is almost equal to that of the tundish hole 6 with
minimum clearance provided to avoid surface to surface contact. This ensures a tight fit
with the tundish hole 6. The top of tubular structure 22 is modified in the form of a hollow
cylinder 24 with a diameter greater than that of the tundish hole 6 such that it securely
gets fixed on top of the tundish hole 6 by the action of the gravity constraining the
movements of the tubular structure 22.
[13] Further the hollow cylinder 24 has appropriate fixtures 19 to lock it firmly to the
mechanical assembly 7; ensuring that its axis is coincident with that of the mechanical
assembly 7 so that the laser beam projection unit 20 projects the beam at right angles
to the base of the tundish 2.
When the laser beam projection unit 20 situated inside the mechanical assembly 7 is
switched on by the power switch 18 a point laser beam 10 points on the ground. This
point on the ground serves as a reference and accurately projects the centre of the
tundish hole 6 onto the ground with the point laser beam 10 showcasing the vertical axis
of the tundish hole 6.
[14] With reference to Figure 5, once the mechanism is firmly installed on the tundish
hole 6 and the laser beam projection unit 20 is switched on, a receiver system is installed
beneath the beam. The receiver system consists of a receiver unit 11, an

analog to digital conversion unit 12, a processing unit 13, and display readout 14 joined
together by means of optical cables. The receiver unit 11 is installed at the centre of a
large circular wooden board 28 with a metal sheet 26 at the bottom to protect the
structure against wear and tear. The structure and its use have been described briefly in
[22].
[15] The receiver unit 11 when placed beneath the point laser beam 10, it can sense its
position in terms of the coordinates on the receiving plane. Referring to Figure 4 the
receiver unit 11 is connected to an analog to digital converter unit 12 by means of
electrical cables which converts the analog input received from the receiver unit 11 to
digital form. The digital output is sent to a processing unit 13 by means of optical cables
which processes the input coordinates and calculates the deviation of the beam from the
centre of the laser beam receiver unit 11 in both x and y directions. The deviations as
input are sent to the display unit 14 which gives visible output to the operator.
[16] The operator then repositions the receiver unit 11 as required such that the deviation
is made null in both x and y directions by successive iterations. The display readout 14
may as well include direction pointers to point the directions along the axis in which the
receiver unit 11 must be moved to reduce the error value to zero. After the error values
have been made null, the apparatus can be removed from the tundish except the receiver
unit 11 which must not be disturbed from its position.
[17] For further process, an apparatus similar to the one mentioned above is constructed
with specific modifications as per the requirement of the process. Figure 8 shows a
tundish 2 mounted on the tundish stand 5 with SEN 4 inserted into the tundish hole6 to
the required depth. The SEN 4 is then locked into the tundish by means of split rings
which hold the SEN 4 preventing it from falling under the influence of gravity.

[18] The apparatus 9 is now installed on the SEN 4 as described further. The same
mechanical assembly 7 for accurate alignment of a laser beam projection unit 20 is used
for the process. The placement device 8 with a similar design is used for the process. The
placement device 8 is modified such that the outer diameter of the tubular structure 22
is almost equal to that of the SEN 4 internal diameter with minimum clearance provided
to avoid damage to the internal surface of the SEN 4. This ensures a tight fit with the
SEN 4. The top of the tubular structure 22 is in the form of a hollow cylinder 24 with the
same diameter as used above so that the placement device 8 gets firmly locked on to the
mechanical assembly 7.
[19] This tubular structure 22 is inserted from the top of the SEN 4 to go vertically inside
the SEN 4 such that the hollow cylinder 24 above gets placed on top of the SEN 4 with
the axis of the hollow cylinder 24 coincident with that of the SEN 4. This ensures that the
projected point laser beam 10 passes through the centre of the SEN 4. Now the
mechanical assembly 7 for accurate alignment of a laser beam projection unit 20 is fit
onto the hollow cylinder 24 by a suitable locking mechanism 19 similar to the one used
in the previous process. On switching on the laser beam projection unit 20 by means of
a power switch 18; the setup ensures that point laser beam 10 passes through the centre
of the top circular portion of the SEN 4. The point laser beam 10 now passes through the
centre of the SEN 4 and strikes the ground at some arbitrary position.
[20] SEN 4 is moved such that the laser beam strikes the receiver unit 11 and as described
in the previous step [15] the display unit 14 shows the distances the SEN 4 bottom should
be moved in the x and y directions to align point laser beam 10 to the centre of the
receiver unit 11. The operator takes the error values displayed on the display unit 14 and
does the necessary corrections in the SEN 4 orientation.

[21] The setup of the receiver system shown in Figure 4 used in the previous step [14]
& [21] has been described briefly hereafter. In reference to Figure 9 the receiver unit 11
is mounted at the centre of a wooden board 28. The thin metal covering 25 at the
periphery shields the mounted system from accidental damage. The base of the wooden
board 28 is protected from wear by thick metal sheet at the bottom 26.
As can be shown in the Figure 9 an arrangement (100) for centering submerged entry
nozzle (SEN) in tundish, two perpendicular diameters 27 are marked on the wooden board
28 such that they are clearly visible from a distance. These two markings serve as
reference for the positioning of the requisite alignment tools. The present embodiment
makes use of multiple optical illuminators positioned on the wooden board28. For
sufficiency, a setup consisting of two optical illuminators 29 has been described hereafter.
The two optical illuminators 29 are placed on the two marked diameters 27 of wooden
board 28 such that one illuminator 29 lies along each diameter 27.
[22] Optical illuminators 29 used in the present embodiment are visible light sources such
as commercially available laser generators and in particular multiple laser generators that
produce a planar, fan shaped beam of visible light 30 in two perpendicular directions. The
beam of light in the plane of the wooden board 28 has been called horizontal beam and
the one perpendicular to the plane of the wooden board 28 has been called the vertical
beam hereafter for the sake of clarity.
Optical illuminators 29 are positioned such that the central axis of the horizontal beams
from the optical illuminators 29 coincides with the marked diameters 27 of the wooden
board 28. The vertical beams are visible on any surface in the plane of the beam which
in our case constitutes the SEN 4 and a portion of the wooden board 28.

When the horizontal beams radiated from optical illuminators 29 are switched on, they
should intersect at the centre of the receiver unit 11 which guides the positioning of the
optical illuminators 29.
For aligning the SEN 4 to the tundish 2, the central line markings on the faces of the SEN
4 serve as reference. These central line markings provide an indication to the operator
about the present position of the SEN 4. Each optical illuminator 29 radiates a vertical
beam one along the front and the other along the side face of the SEN 4.
[23] The vertical beams on both the sides of the SEN 4 serve to indicate the accurate
position to which the central line markings of the SEN 4 must be aligned for correct
alignment of the SEN 4. The operator shifts the SEN 4 such that the central line markings
on both the faces of the SEN 4 are respectively aligned with the vertical beams projected
by the optical illuminators 29. The laser beam projection unit 20 housed within the
mechanical assembly 7 continuously projects the point laser beam 10 on the receiver
unit11.
As described earlier in [15], the receiver unit 11 sends these analog data to analog to
digital converter 12 which sends the digitised data to the processing unit 13. The
processing unit 13 does the necessary computations and sends the deviations of the SEN
4 in both the directions from the central point as input to the display unit 14 which gives
visible output to the operator.
When the operator correctly aligns the SEN 4 such that the central axis of the SEN 4 is
perfectly aligned at ninety degrees to the base of the tundish 2, the display unit 14 will
give the error value of zero in both the x and y axes indicating that the SEN 4 is perfectly
aligned to the tundish 2.

[24] After the SEN 4 has been attached to the tundish 2 with proper alignment, the SEN
4 needs to be aligned at the centre of the mold 3 to ensure correct alignment of the
system. An apparatus for aligning the SEN 4 precisely at the centre of the mold 3 has
been described hereafter.
While this invention is susceptible to embodiment in many different forms, this is shown
in the drawings and will be described herein in detail specific embodiments thereof with
the understanding that the present disclosure is to be considered as an exemplification
of the principles of the invention and is not to be limited to the specific embodiments
thereof.
[25] Figure 10 illustrates a system (200) showing an embodiment of an optical system
for centering the SEN 4 in the mold 3. As shown in the figure, a laser based system
comprising of two laser based distance measurement systems 31, central processing unit
32, display unit 33 and an integrated software 34 has been described which accurately
displays the distances and the direction SEN should be shifted to align it at the center of
the mold 3.
[26] Referring to Figure 10, the SEN 4 attached to the tundish 2 is immersed inside the
mold 3. The top surface of the mold is labelled 3a while the funnel is labelled 3b.
Two laser based distance measurement systems 31 are placed at a convenient distance
from the centre so that they can measure the distance of the SEN 4 from their positions
accurately to the required level of accuracy while ensuring that the laser based distance
measurement systems 31 to be at sufficient distance to not get damaged from the
radiated heat. These laser based distance measurement systems 31 are placed such that
the emitted beams are coincident with the centre line of the funnel 3b. This ensures
distance is always measured symmetrically and the reference position remains constant.

When the power is supplied to the laser based distance measurement systems 31 through
the power control unit two laser beams perpendicular to each other are emitted from the
laser based distance measurement systems 31 which hit the SEN 4 measuring the
distance of the SEN 4 from the laser based distance measurement systems 31 along the
respective directions.
[27] As shown in Figure 11, this data is transferred to the Central Processing unit 32
which processes the data and calculates the deviation of the SEN 4 from the center of
the mold 3. The central processing unit 32 processes the data received in reference to
the previously stored offsets, central axes, etc. which has been fed initially during the
system installation. The finally calculated deviations of the SEN 4 from the centre of the
mold 3 in both the x and y directions are displayed on the display unit 33. The display
unit 33 also indicates the direction the SEN 4 should be shifted along the x and y axis.
Referring to figure 11, the data from the Central Processing unit 32 passes to software
on the PC 34 which plots the current position of the SEN 4 with respect to the mold 3 on
x-y coordinate plane. This graphical output can be displayed in the control room ensuring
the complete monitoring of the process.
[28] Method for SEN Alignment
Tundish Preparation Area
• Projecting centre of tundish hole onto the ground
I. Placement device 8 is attached to the bottom of the mechanical assembly
II. The mechanical assembly with the placement device attached is installed onto
the tundish hole such that the top hollow part of the tubular structure is firmly
seated onto the tundish hole
III. Laser beam projection unit 20 is switched on to cast a beam of light
perpendicular to the tundish hole
IV. Receiver system is installed and receiver unit is place below the laser beam from
the laser beam projection unit
V. Receiver unit is moved such that the display unit shows null values along both
the axes

VI. Laser beam projection unit is switched off and mechanical assembly along with
the placement device is removed
• Installing the SEN with perfect alignment
• For SEN with central hole as depicted in Figure 8
I. SEN is temporarily placed inside the tundish hole
II. Mechanical assembly with placement device is installed on top of the SEN such
that top hollow part of the tubular structure is firmly seated onto the top of the
SEN
III. Laser beam projection unit is switched on and the readings on the display unit
are observed
IV. SEN orientation is corrected such that the display unit shows null values along
both the axes
• For SEN without central hole (and for additional reference)
I. SEN is temporarily placed inside the tundish hole
II. Optical illuminators installed on the wooden board are switched on to cast planar
beam of visible light
III. SEN is moved such central lines on the side faces of SEN coincide with the
projected beam of visible light along both the axes
Operation Area as depicted in Figure 10
I. Laser based distance measurement systems are installed along the perpendicular
sides of the mold
II. The distance measured along both the axes is used to calculate the final
deviations of the SEN from the centre position which is displayed on the display
unit
III. SEN position is corrected such that the display unit shows null values along both
the axes

WE CLAIM
The invention claimed is:
1. An arrangement (100) for centering submerged entry nozzle (SEN) in tundish, the
arrangement (100) comprising:
a submerged entry nozzle (4) being line marked with atleast two orientation lines at
adjacent faces of the submerged entry nozzle (4), the submerged entry nozzle (4)
being coupled with tundish (2);
a self-leveled board (28) marked with atleast two reference markings separated by
an angle, each reference markings being positioned with a laser generator (29, 29);
the laser generators (29) being configured to illuminate the orientation lines over the
SEN to be superimposed with hit and trial method; and
centering the SEN being achieved once the superimposing is done.
2. The arrangement (100) as claimed in claim 1, wherein the angle between orientation
lines is 90 deg.
3. The arrangement (100) as claimed in claim 1, wherein the submerged entry nozzle
(SEN) is comprised of an apparatus (9) at the top, the apparatus (9) is being
configured to fix SEN in tundish and carrying a point laser to align submerged entry
nozzle with self-leveled board (28).
4. The arrangement (100) as claimed in claim 3, wherein the apparatus (9) is comprised
of a mechanical assembly (7) and a placement means (8), the mechanical assembly
(7) is being configured to be fixed with tundish and the placement means (8) is
configured to be coupled with the mechanical assembly (7).

5. A system (200) for centering submerged entry nozzle (4) in caster mold (3), the system
(200) comprising:
a submerged entry nozzle (4) being line marked with atleast two orientation lines at
adjacent faces of the submerged entry nozzle (4), the submerged entry nozzle (4)
being coupled with tundish (2);
at least two laser distance measuring equipments (31, 31) configured to illuminate
the orientation lines to assess gap between SEN and mold at one face and adjacent
face;
the laser distance measurement equipments (31, 31) being coupled to a central
processing unit (32) of computer system to extract assessed value from the
equipments, the central processing unit (32) having a predetermined reference values
of gap and compared the assessed value with reference value, displaying the amount
of shift required.