U.S. patent application number 12/097952 was filed with the patent office on 2009-02-12 for casting roll moving apparatus of twin roll type continuous strip casting process.
This patent application is currently assigned to Posco Co., Ltd.. Invention is credited to Tae-Wook Kang, Sang-Hoon Kim, Cheol-Min Park, Du-Hyong Yoon.
Application Number | 20090038771 12/097952 |
Document ID | / |
Family ID | 37713808 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090038771 |
Kind Code |
A1 |
Park; Cheol-Min ; et
al. |
February 12, 2009 |
Casting Roll Moving Apparatus of Twin Roll Type Continuous Strip
Casting Process
Abstract
A casting roll moving apparatus for a twin roll type continuous
strip casting process is disclosed. The casting roll moving
apparatus 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 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. 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. 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.
Inventors: |
Park; Cheol-Min;
(Kyungsangbuk-do, KR) ; Yoon; Du-Hyong;
(Kyungsangbuk-do, KR) ; Kang; Tae-Wook;
(Kyungsangbuk-do, KR) ; Kim; Sang-Hoon;
(Kyungsangbuk-do, KR) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING, 436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Assignee: |
Posco Co., Ltd.
Pohang-shi
KR
|
Family ID: |
37713808 |
Appl. No.: |
12/097952 |
Filed: |
March 16, 2006 |
PCT Filed: |
March 16, 2006 |
PCT NO: |
PCT/KR2006/000972 |
371 Date: |
June 18, 2008 |
Current U.S.
Class: |
164/428 |
Current CPC
Class: |
B22D 11/0622 20130101;
B22D 11/0651 20130101 |
Class at
Publication: |
164/428 |
International
Class: |
B22D 45/00 20060101
B22D045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2005 |
KR |
10-2005-0130387 |
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).
Description
TECHNICAL FIELD
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] The rolling force due to friction generates the hunting of
the rolling force during a casting process.
[0010] This is generated in every casting process and causes uneven
rolling force.
[0011] Hence, the surface of the cast strip may deteriorate. That
is, a defect, in which uneven patterns are formed on the surface,
may occur.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] This method has been used in a hot rolling mill and in a
medium cast.
[0018] In the hot rolling mill, this method is appropriate, because
rolls must be moved as required and a slab is in a stationary
state.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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
[0023] Technical Tasks to be Solved by the Invention
[0024] 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.
[0025] Technical Solution
[0026] 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.
[0027] 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.
[0028] 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.
[0029] Advantageous Effects
[0030] 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
[0031] FIG. 1 is a schematic view showing a conventional twin roll
type continuous strip casting process;
[0032] FIG. 2 is views showing examples of defective arrangement of
rolls in the conventional art;
[0033] FIG. 3 is a view showing an example of a typical LM (linear
motion guide);
[0034] FIG. 4 is a schematic view of a casting roll moving
apparatus according to an embodiment of the present invention;
[0035] FIG. 5 is an illustrative view showing the operation of the
casting roll moving apparatus according to the present
invention;
[0036] FIG. 6 is a view showing an operating structure of the
casting roll moving apparatus according to the present
invention;
[0037] 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
[0038] 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
[0039] Hereinafter, the present invention will be described in
detail with reference to the attached drawings.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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
[0050] 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.
[0051] The results were shown in FIGS. 7 and 8.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
* * * * *