CASTING ROLL MOVING APPARATUS OF TWIN ROLL TYPE
CONTINUOUS STRIP CASTING PROCESS
Technical Field
The present invention relates, in general, to casting roll moving
apparatuses for twin roll type continuous strip casting machines which have
structures such that casting rolls can smoothly move with reduced friction, and
in which, if opposite ends of the casting roll become misaligned, they are
automatically realigned and, more particularly, to a casting roll moving
apparatus for a twin roll type continuous strip casting process which supports
casting rolls using hydraulic pressure and reduces friction through the formation
of fluid films during a casting process, so that, if opposite ends of the casting
rolls become misaligned by the application of uneven rolling force to the casting
rolls, or if the gap between the casting rolls becomes uneven due to longitudinal
outside force or due to skull entering between the casting rolls, the casting rolls
are automatically realigned, that is, are returned to the original positions thereof.
Background Art
As well known to those skilled in the art, an S/C (strip casting) process
is a process of producing a cast strip 3 by supplying a steel melt 2 between two
rolls 1, which are rotating.
In a twin roll type strip casting machine of the S/C process, edge dams
are coupled to opposite ends of the casting rolls such that steel melt is prevented
from leaking, thus forming a steel melt pool for supplying steel melt between the
casting rolls.
The steel melt is solidified while passing through the steel melt pool and
is produced into a cast strip after passing through a roll nip.
In the steel melt pool, solidifying shells meet each other and are
depressed at high temperature, thus being produced into a cast strip having a
plate shape. The point at which the solidifying shells meet each other is called
a solidification completion point, and the next section is called a thermal
deformation section.

The thermal deformation section has the same role as a hot rolling line.
Furthermore, a rolling force is generated by roll separation force when passing
the thermal deformation section.
As well, to maintain the thickness of a cast strip constant, the two rolls
are continuously moved such that the distance between the two rolls is
maintained.
Here, the generated rolling force is divided into pressure due to
solidification and rolling force due to friction at a lower position resulting from
movement of the rolls.
The rolling force due to friction generates the hunting of the rolling force
during a casting process.
This is generated in every casting process and causes uneven rolling
force.
Hence, the surface of the cast strip may deteriorate. That is, a defect, in
which uneven patterns are formed on the surface, may occur.
Furthermore, FIG. 2 shows the case in which the opposite ends of the
rolls are undesirably misaligned or a gap between the rolls is made uneven by
longitudinal outside force or by an uneven increase in the distance between the
rolls due to skulls that enter between the rolls.
These directly affect the quality of strip edges, thus the casting process
becomes unstable, for example, the recovery rate is reduced or a defective
winding phenomenon is caused. In addition, the casting process may be
interrupted.
These problems occur because the opposite ends of the rolls, which have
been misaligned, cannot be rapidly returned to the original states thereof by the
friction of a moving apparatus, which is provided under the rolls, and because
the conventional art has no means for rapidly returning the rolls to the original
states thereof during the casting process.
Conventional techniques for solving the above problems are classified
into two kinds of techniques. The first conventional technique is related to a
strip casting (S/C) process, and the second conventional technique is related to a
hydrostatic bearing.
A slide guide technique is one strip casting related technique. A slide
guide slides on a wear plate using grease applied to the wear plate.
This method has been used in a hot rolling mill and in a medium cast.

In the hot rolling mill, this method is appropriate, because rolls must be
moved as required and a slab is in a stationary state.
However, in the S/C process, because steel melt in a liquid phase is
treated and roll edges must be reliably sealed, it is inappropriate to use this
method.
Meanwhile, there is an LM guide (linear motion guide). As shown in
FIG. 3, the LM guide includes a rail 6 and a carriage 5. A sliding bearing is
installed in the LM guide. The LM guide is widely used in an automation
system.
However, in the case that it is used for a long time, durability thereof is
reduced by heat generated by friction. Furthermore, there is a problem in that
it is difficult to realign the opposite ends of the LM guide when the LM guide is
misaligned by outside force.
In the conventional technique related to the hydrostatic bearing, there is
the case in which the hydrostatic bearing is used in an LM guide. However,
because this incorporates a rail and carriage, a problem in which the LM guide
twists cannot be solved.
Disclosure of the Invention
Technical tasks to be solved by the invention
Accordingly, the present invention has been made keeping in mind the
above problems occurring in the prior art, and an object of the present invention is
to provide a casting roll moving apparatus of a twin roll type continuous strip
casting process which is operated by hydraulic pressure and forms fluid films to
reduce friction, and in which, if overload is applied to rolls, the rolls are
automatically realigned, thus solving problems of misalignment of the opposite
ends of the rolls and of unstable rolling force and unstable roll gap during a
casting process.
Technical Solution
In order to accomplish the above object, the present invention provides a
casting roll moving apparatus which can be used with a twin roll type strip casting
machine that produces a strip through a method in which, while high-temperature
steel melt is supplied between twin rolls which rotate in opposite direction, a large

amount of heat is dissipated through the rolls by contact between the steel melt
and the rolls, so that the steel melt is rapidly solidified.
The present invention provides a casting roll moving apparatus of a twin
roll type continuous strip casting process, including: a bearing housing supporting
a casting roll shaft; a saddle coupled to the lower end of the bearing housing, with
a sliding protrusion vertically protruding from a lower surface of the saddle; a mill
frame having therein a receiving space so that the sliding protrusion of the saddle
is movably inserted in the receiving space, pads provided on respective opposite
sidewalls of the receiving space of the mill frame such that the pads are parallel to
respective opposite side surfaces of the sliding protrusion of the saddle, and a shoe
provided on the bottom of the receiving space such that the shoe is parallel to the
lower surface of the sliding protrusion; and a hydraulic pressure supplying means
for supplying fluid to opposite sidewalls and the bottom of the receiving space of
the mill frame. The fluid supplying means includes a fluid storage tank storing
the fluid, and a fluid distribution pipe line distributing the fluid from the fluid
storage tank to the receiving space.
Furthermore, in the present invention, each of the shoe and the pads has a
nozzle to discharge the fluid to the sliding protrusion. The shoe and the pads
comprise two or more shoes and pads such that hydraulic pressure is evenly
applied to the overall opposite side surfaces and the overall lower surface of the
sliding protrusion. Hydraulic pressures, which are substantially equal to each
other, are applied between the pads and the sliding protrusion of the saddle. The
casting roll moving apparatus further includes a fluid discharge pipe provided in
the bottom of the receiving space of the mill frame to discharge the fluid, supplied
from the hydraulic pressure supplying means, outside the receiving space. The
fluid discharge pipe is connected to a circulation pipe so that the fluid is returned
to the fluid storage tank. The fluid distribution pipe line includes a shock
absorber 22 and a fluid distributor 23.
Advantageous Effects
As described above, in the casting roll moving apparatus of the present
invention, opposite ends of the casting rolls are automatically aligned, so that the
recovery rate of the apparatus is increased, and a stable casting process is
ensured. Furthermore, because friction of the apparatus is markedly reduced,
by which even rolling force is ensured, the gap between the rolls is maintained

constant. Thus, the thickness of a cast strip becomes even, and a problem of an
uneven surface pattern is solved.
Brief Description of Drawings
FIG. 1 is a schematic view showing a conventional twin roll type
continuous strip casting process;
FIG. 2 is views showing examples of defective arrangement of rolls in
the conventional art;
FIG. 3 is a view showing an example of a typical LM (linear motion
guide);
FIG. 4 is a schematic view of a casting roll moving apparatus according to
an embodiment of the present invention;
FIG. 5 is an illustrative view showing the operation of the casting roll
moving apparatus according to the present invention;
FIG. 6 is a view showing an operating structure of the casting roll moving
apparatus according to the present invention;
FIG. 7 is graphs comparing the results of rolling force tests between the
moving apparatus of the present invention and the conventional moving
apparatus; and
FIG. 8 is pictures comparing the edges of cast strips using the moving
apparatus of the present invention and using the conventional moving apparatus.
Best Mode for Carrying Out the Invention
Hereinafter, the present invention will be described in detail with
reference to the attached drawings.
FIG. 4 is a schematic view of a casting roll moving apparatus according to
an embodiment of the present invention. FIG. 5 is an illustrative view showing
the operation of the casting roll moving apparatus of the present invention.
Referring to the drawings, in the casting roll moving apparatus of the
present invention, bearing housings 11 surround and support a roll shaft 1-1,
which is integrated with a casting roll 1. Furthermore, each bearing housing 11
is coupled to each mill frame 13 through a saddle 12. A sliding protrusion 12-1
protrudes downwards from a central portion of the lower surface of each saddle

12. Furthermore, the saddle 12 is coupled to the lower surface of the bearing
housing 11 using bolts or the like.
Each mill frame 13 has in an upper surface thereof a receiving space 16,
in which the sliding protrusion 12-1 is movably inserted. Pads 15 are attached to
the opposite sidewalls of the receiving space 16 such that the sliding protrusion
12-1 and the pads 15 maintain constant distance therebetween and are parallel to
each other. A shoe 14 is provided on the bottom of the receiving space 16 such
that it is parallel to and maintains a constant distance from the lower surface of the
sliding protrusion 12-1. A nozzle 17 for discharging fluid to the sliding
protrusion 12-1 is installed in each of the shoes 14 and the pads 15. It is
preferable that two or more nozzles 17 be provided at positions corresponding to
the sliding protrusion 12-1 to evenly apply pressure to the sidewalls and the lower
surface of the sliding protrusion 12-1.
A fluid storage tank 18 and a fluid distribution pipe line 20 for supplying
fluid into the receiving space 16 of the mill frame 13 and a circulation pipe 21 for
returning used fluid from the receiving space 16 to the fluid storage tank 18 are
provided outside the mill frame 13.
The fluid distribution pipe line 20 is coupled to the shoe 14 and the pads
15 of the receiving space 16, and the fluid circulation pipe 21 is connected to a
fluid discharge pipe 19, which is provided in the bottom of the receiving space 16.
In the present invention, having the above-mentioned construction, during
a casting process, fluid is continuously supplied at a constant pressure to the shoe
14 and the pads 15 of the receiving space 16 through the fluid distribution 20.
The supplied fluid is discharged to the opposite sidewalls and the lower surface of
the sliding protrusion 12-1 of the saddle at the same pressure through the nozzles
17, thus forming fluid films thereon.
Therefore, the sliding protrusion 12-1 maintains the initial position thereof
because fluid is discharged to the opposite sidewalls of the sliding protrusion 12-1
at even pressure. Thereby, the casting roll 1 can also maintain the original
position thereof, thus making a normal casting operation possible.
As shown in FIGS. 5(a), during the casting process, when the roll is
moved in one direction by outside force applied to the roll, a difference in
hydraulic pressure occurs between the opposite sidewalls of the sliding protrusion.
That is, hydraulic pressure is increased at the side at which the gap is reduced, so

that the roll is automatically returned to the original position thereof while the
uneven hydraulic pressure state is changed to an even hydraulic pressure state.
As shown in FIGS. 5(b), even when the opposite ends of the roll are
moved in different directions because uneven outside force is applied to the roll,
hydraulic pressure is increased at the side at which the gap is reduced, thus the roll
is automatically returned to the original position thereof.
As such, in the present invention, fluid films are formed both between the
sliding protrusion and the pads and between the sliding protrusion and the shoe by
hydraulic pressure discharged from the shoe and the pads, thus the saddle can
smoothly move with reduced friction. Furthermore, the saddle can be
automatically returned to the original position thereof by hydraulic pressure,
which is evenly discharged.
(Example)
The hunting values of rolling forces, cast strip edges and wound
conditions between a coil manufactured using the apparatus of the present
invention and a coil manufactured using the conventional apparatus were
compared.
The results were shown in FIGS. 7 and 8.
As shown in FIG. 7, it is appreciated that the data loading value of the
rolling force of the apparatus of the present invention is markedly improved
compared to that of the conventional apparatus.
In detail, the hunting value of the rolling force, which was +-3 ton, is
reduced to +-0.5 ton. Thereby, stability of the roll gap is realized, so that
variation in the thickness of the cast strip is reduced.
That is, in the conventional art, variation in the thickness of the cast strip
in the longitudinal direction ranges from 70 to 100 microns, but, in the present
invention, it is reduced to 20 to 30 microns. This is very important in the art,
because the variation in thickness of the cast strip affects a subsequent rolling
process.
Furthermore, as shown in FIG. 8, the cast strip edge and the winding
condition of the present invention were also found to be superior to those of the
conventional art. It is assumed that this was achieved because the arrangement
of opposite ends of the casting rolls was satisfactory thanks to the maintenance of
stiffness by preloading. As a result, the recovery rate of the cast strip edge is
markedly enhanced.

Claims:
1. A casting roll moving apparatus for a twin roll type continuous strip
casting process, comprising:
a bearing housing (11) supporting a casting roll shaft (1-1);
a saddle (12) coupled to a lower end of the bearing housing (11), with a
sliding protrusion (12-1) vertically protruding from a lower surface of the saddle
(12);
a mill frame (13) having therein a receiving space (16), so that the sliding
protrusion (12-1) of the saddle (12) is movably inserted in the receiving space
(16); and
hydraulic pressure supplying means for supplying fluid to opposite
sidewalls and a bottom of the receiving space (16) of the mill frame (13).
2. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 1, wherein the saddle (12) is coupled to the
bearing housing (11) using a bolt.
3. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 1, further comprising:
pads (15) provided on respective opposite sidewalls of the receiving space
(16) of the mill frame such that the pads (15) are parallel to respective opposite
side surfaces of the sliding protrusion (12-1) of the saddle; and
a shoe (14) provided on the bottom of the receiving space (16) such that
the shoe (14) is parallel to a lower surface of the sliding protrusion (12-1).
4. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 3, wherein each of the shoe (14) and the pads
(15) has a nozzle (17) to discharge the fluid to the sliding protrusion (12-1).
5. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 3, wherein the shoe (14) and the pads (15)
comprise two or more shoes (14) and pads (15) such that hydraulic pressure is
evenly applied to all of both of the opposite side surfaces and the entire lower
surface of the sliding protrusion (12-1).

6. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 3, wherein hydraulic pressures, which are
substantially equal to each other, are applied between the pads (15) and the sliding
protrusion (12-1) of the saddle.
7. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 1, wherein the fluid supplying means
comprises a fluid storage tank (18) storing the fluid, and a fluid distribution pipe
line (20) distributing the fluid from the fluid storage tank (18) to the receiving
space (16).
8. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 1, further comprising:
a fluid discharge pipe (19) provided in the bottom of the receiving space
(16) of the mill frame to discharge the fluid, supplied from the hydraulic pressure
supplying means, outside the receiving space (16).
9. The casting roll moving apparatus for the twin roll type continuous strip
casting process according to claim 8, wherein the fluid discharge pipe (19) is
connected to a circulation pipe (21) so that the fluid is restored into the fluid
storage tank (18).
10. The casting roll moving apparatus for the twin roll type continuous
strip casting process according to claim 7, wherein the fluid distribution pipe line
(20) comprises a shock absorber (22) and a fluid distributor (23).

A casting roll moving apparatus for a twin roll type continuous strip casting process is disclosed. The casting roll
moving apparatus of the present invention is used with a twin roll type strip casting machine that produces a strip through a method
in which, while high-temperature steel melt is supplied between twin rolls (1) which rotate in opposite direction, a large amount of
heat is dissipated through the rolls by contact between the steel melt and the rolls, so that the steel melt is rapidly solidified. In the
present invention, opposite ends of the rolls are automatically aligned, so that the recovery rate of the apparatus is increased, and a
stable casting process is ensured. Furthermore, because friction of the apparatus is markedly reduced so that an even rolling force is
ensured, a gap between the rolls is maintained constant. Thus, the thickness of a cast strip is maintained constant, and the problem
of the occurrence of an uneven surface pattern is solved.