U.S. patent application number 17/628463 was filed with the patent office on 2022-08-18 for casting equipment and casting method.
This patent application is currently assigned to POSCO. The applicant listed for this patent is POSCO. Invention is credited to Hyun Jin CHOI, Sang Woo HAN, Jin Ho LEE, Seung Jae LEE, In Beom PARK.
Application Number | 20220258227 17/628463 |
Document ID | / |
Family ID | 1000006363543 |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220258227 |
Kind Code |
A1 |
HAN; Sang Woo ; et
al. |
August 18, 2022 |
CASTING EQUIPMENT AND CASTING METHOD
Abstract
The present disclosure relates to a casting apparatus and a
casting method. The casting method includes injecting a molten
material into a mold by using a nozzle, forming a static magnetic
field applied region and a non-static magnetic field applied region
in a width direction of the mold and controlling a flow of the
molten material in a longitudinal direction of the mold, and
drawing a cast slab. Through this, as the flow of the molten
material accommodated in a container is locally controlled,
cleanliness of the molten material may be secured, and a quality of
a product may be improved.
Inventors: |
HAN; Sang Woo; (Pohang-si,
Gyeongsangbuk-Do, KR) ; PARK; In Beom; (Gwangyang-Si,
Jeollanam-Do, KR) ; CHOI; Hyun Jin; (Pohang-si,
Gyeongsangbuk-Do, KR) ; LEE; Seung Jae;
(Gwangyang-Si, Jeollanam-Do, KR) ; LEE; Jin Ho;
(Pohang-si, Gyeongsangbuk-Do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
POSCO |
Pohang-si, Gyeongsangbuk-Do |
|
KR |
|
|
Assignee: |
POSCO
Pohang-si, Gyeongsangbuk-Do
KR
|
Family ID: |
1000006363543 |
Appl. No.: |
17/628463 |
Filed: |
July 1, 2020 |
PCT Filed: |
July 1, 2020 |
PCT NO: |
PCT/KR2020/008597 |
371 Date: |
January 19, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 11/166 20130101;
B22D 11/115 20130101 |
International
Class: |
B22D 11/115 20060101
B22D011/115; B22D 11/16 20060101 B22D011/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2019 |
KR |
10-2019-0175835 |
Claims
1. A casting apparatus for casting a cast slab, comprising: a mold
configured to provide an inner space for accommodating a molten
material; a nozzle disposed above the mold to supply the molten
material into the mold; a static magnetic field generation unit
disposed on an outside in a width direction of the mold so that
magnetic fields at both edges in the width direction of the mold
are controlled in different directions; and a control unit
configured to control an operation of the static magnetic field
generation unit.
2. The casting apparatus of claim 1, wherein the mold comprises one
pair of long side plates spaced apart from each other and one pair
of short side plates configured to connect both sides of each of
the one pair of long side plates, and the static magnetic field
generation unit comprises: a plurality of static magnetic field
generators disposed in a width direction of the long side plate
below the nozzle so as to be spaced apart from a central portion in
the width direction of the mold; and a first current supplier
configured to supply a direct current to the plurality of static
magnetic field generators so as to form a magnetic field passing in
a thickness direction of the mold at both sides of the nozzle in
the width direction of the mold.
3. The casting apparatus of claim 2, wherein each of the plurality
of static magnetic field generators comprises: a core extending
along a portion of the width direction of the long side plate and
spaced apart from another core; and a coil wound around an outside
of the core.
4. The casting apparatus of claim 3, wherein the plurality of
static magnetic field generators comprise: a first static magnetic
field generator; a second static magnetic field generator disposed
at one side of the first static magnetic field generator while
being spaced apart therefrom so that the nozzle is disposed
therebetween; a third static magnetic field generator disposed to
face the second static magnetic field generator; and a fourth
static magnetic field generator disposed at one side of the third
static magnetic field generator while being spaced apart therefrom
so that the nozzle is disposed therebetween and disposed to face
the first static magnetic field generator, and the first current
supplier supplies a direct current to the first static magnetic
field generator, the second static magnetic field generator, the
third static magnetic field generator, and the fourth static
magnetic field generator so as to form opposite polarities in
directions facing each other in the thickness direction of the mold
and opposite polarities in the width direction of the mold.
5. The casting apparatus of claim 4, wherein the first static
magnetic field generator and the second static magnetic field
generator are spaced by a first distance from each other, and the
third static magnetic field generator and the fourth static
magnetic field generator are spaced by a second distance from each
other, wherein the first distance is the same as the second
distance.
6. The casting apparatus of claim 5, wherein when the cast slab has
an entire width of 100, each of the first distance and the second
distance is in a range from 4 to 36.
7. The casting apparatus of claim 6, wherein at least one of the
first static magnetic field generator, the second static magnetic
field generator, the third static magnetic field generator, and the
fourth static magnetic field generator is movable along the width
direction of the mold.
8. The casting apparatus of claim 7, further comprising: a first
connection core configured to connect the first static magnetic
field generator and the second static magnetic field generator; and
a second connection core configured to connect the third static
magnetic field generator and the fourth static magnetic field
generator.
9. The casting apparatus of claim 8, wherein the static magnetic
field generation unit forms a magnetic field that rotates in a
circumferential direction of the mold.
10. The casting apparatus of claim 1, further comprising a dynamic
magnetic field generation unit disposed above the static magnetic
field generation unit to form a dynamic magnetic field for
controlling a flow of the molten material, wherein the control unit
controls an operation of the dynamic magnetic field generation unit
so as to adjust at least one of an intensity and a direction of the
dynamic magnetic field.
11-12. (canceled)
13. A casting method comprising: injecting a molten material into a
mold by using a nozzle; forming a static magnetic field applied
region and a non-static magnetic field applied region in a width
direction of the mold and controlling a flow of the molten material
in a longitudinal direction of the mold; and drawing a cast
slab.
14. The casting method of claim 13, further comprising, before the
injecting of the molten material, arranging the nozzle at a central
portion in the width direction of the mold, wherein the controlling
of the flow of the molten material comprises forming the non-static
magnetic field applied region at a central portion in the width
direction of the mold and forming the static magnetic field applied
region at both sides of the non-static magnetic field applied
region.
15. The casting method of claim 14, wherein the controlling of the
flow of the molten material comprises forming the static magnetic
field applied region and the non-static magnetic field applied
region below the nozzle.
16. The casting method of claim 15, wherein the controlling of the
flow of the molten material comprises forming a magnetic field
along a thickness direction of the mold, and the forming of the
static magnetic field applied region comprises forming a static
magnetic field so that magnetic fields at both sides of the nozzle
have opposite directions.
17. The casting method of claim 16, wherein the controlling of the
flow of the molten material comprises forming the non-static
magnetic field applied region at a portion of the central portion
in the width direction of the mold, at which the nozzle is
disposed.
18. The casting method of claim 17, wherein the controlling of the
flow of the molten material comprises controlling a range of the
static magnetic field applied region so that the non-static
magnetic field applied region has a magnetic field of 0 Gauss to
100 Gauss.
19. The casting method of claim 18, wherein the controlling of the
flow of the molten material comprises adjusting a distance between
the static magnetic field applied regions according to a width of
the cast slab.
20. The casting method of claim 19, wherein the controlling of the
flow of the molten material comprises forming the static magnetic
field applied region at both edges in the width direction of the
mold to reduce a flow velocity of a downflow of the molten material
and forming the non-static magnetic field applied region between
the static magnetic field applied regions to form an upflow of the
molten material.
21. The casting method of claim 20, wherein the controlling of the
flow of the molten material further comprises forming a dynamic
magnetic field applied region and a non-dynamic magnetic field
applied region to control the flow of the molten material in the
width direction of the mold.
22. The casting method of claim 21, wherein the controlling of the
flow of the molten material in the width direction of the mold
comprises forming a dynamic magnetic field applied region and a
non-dynamic magnetic field applied region between a molten surface
of the molten material and a lower end of the nozzle.
23-24. (canceled)
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a casting apparatus and a
casting method, and more particularly, to a casting apparatus and a
casting method, which are capable of controlling a flow of a molten
material to secure a cleanliness of the molten material, thereby
improving a quality of a product.
BACKGROUND ART
[0002] In general, a continuous casting process may produce various
shaped cast slabs such as a slab, a bloom, a billet, and a beam
blank by injecting molten steel into a mold having a predetermined
inner shape and continuously drawing a semi-solidified cast slab
downward from the mold. The cast slab produced as described above
has a surface quality and an inner quality, which are affected by
various factors. Particularly, the surface quality of the cast slab
is highly affected by a flow of the molten steel in the mold.
[0003] When a molten material is injected into a mold by using a
submerged entry nozzle in the continuous casting process, the
molten material discharged from a discharge hole of the submerged
entry nozzle forms a jet stream to flow in a width direction of the
mold. The molten material flowing in the width direction of the
mold collides an inner surface of the mold, e.g., an inner surface
of a short side plate, so that a portion of the molten material
forms an upflow, and a portion thereof forms a downflow. The upflow
moves to a central portion of the mold around a molten surface of
the molten material, e.g., a portion at which the submerged entry
nozzle is installed. The molten material moving toward the central
portion of the mold collides with the molten material moving in an
opposite direction and the submerged entry nozzle to form a vortex
at the molten surface around the submerged entry nozzle, thereby
causing instability of the flow of the molten surface. Here, the
instability of the flow of the molten surface becomes worse as a
flow velocity of the upflow increases and causes a different kind
of material such as mold slag or mold flux disposed at an upper
portion of the molten surface of the molten material to be mixed
into the molten material.
[0004] Also, the downflow flows downward along an edge of the mold
to form a secondary upflow moving upward at the central portion of
the mold. Here, as the inclusions contained in the molten steel
moves along a casting direction with the downflow and floats with
the secondary upflow, the inclusions may flow into the mold slag or
the mold flux and be removed together. However, when the movement
distance of the inclusion is changed according to a flow velocity
of the downflow, and the downflow has a fast flow velocity, the
inclusion is permeated to a solidified cell and causes a surface
defect of the produced cast slab.
[0005] To resolve the above-described limitation, a method of
controlling the flow of the molten steel in the mold by installing
a magnetic field generator in the mold is used. By using this
method, the mold flux is restricted from flowing into the molten
steel by controlling the upflow around the molten surface of the
molten steel, and the movement distance of the inclusion is
controlled by controlling the downflow below the submerged entry
nozzle to restrict the surface defect of the cast slab from being
generated. However, in the process of controlling the downflow,
formation of the secondary upflow generated by the downflow is also
restricted. Accordingly, the inclusion moving in the casting
direction with the downflow is remained in the molten steel instead
of floating properly to cause degradation in quality of the cast
slab. [0006] (Related art document 1) KR10-1176816 B [0007]
(Related art document 2) JP4411945 B
DISCLOSURE OF THE INVENTION
Technical Problem
[0008] The present disclosure provides a casting apparatus capable
of controlling a flow of a molten material and a casting
method.
[0009] The present disclosure also provides a casting apparatus
capable of smoothly removing an inclusion contained in a molten
material and restricting a different kind of material from being
mixed into the molten material to improve a quality of a product
and a casting method.
Technical Solution
[0010] In accordance with an exemplary embodiment, a casting
apparatus for casting a cast slab includes: a mold configured to
provide an inner space for accommodating a molten material; a
nozzle disposed above the mold to supply the molten material into
the mold; a static magnetic field generation unit disposed on an
outside in a width direction of the mold so that magnetic fields at
both edges in the width direction of the mold are controlled in
different directions; and a control unit configured to control an
operation of the static magnetic field generation unit.
[0011] The mold may include one pair of long side plates spaced
apart from each other and one pair of short side plates configured
to connect both sides of each of the one pair of long side plates,
and the static magnetic field generation unit may include: a
plurality of static magnetic field generators disposed in a width
direction of the long side plate below the nozzle so as to be
spaced apart from a central portion in the width direction of the
mold; and a first current supplier configured to supply a direct
current to the plurality of static magnetic field generators so as
to form a magnetic field passing in a thickness direction of the
mold at both sides of the nozzle in the width direction of the
mold.
[0012] Each of the plurality of static magnetic field generators
may include: a core extending along a portion of the width
direction of the long side plate and spaced apart from another
core; and a coil wound around an outside of the core.
[0013] The plurality of static magnetic field generators may
include: a first static magnetic field generator; a second static
magnetic field generator disposed at one side of the first static
magnetic field generator while being spaced apart therefrom so that
the nozzle is disposed therebetween; a third static magnetic field
generator disposed to face the second static magnetic field
generator; and a fourth static magnetic field generator disposed at
one side of the third static magnetic field generator while being
spaced apart therefrom so that the nozzle is disposed therebetween
and disposed to face the first static magnetic field generator, and
the first current supplier may supply a direct current to the first
static magnetic field generator, the second static magnetic field
generator, the third static magnetic field generator, and the
fourth static magnetic field generator so as to form opposite
polarities in directions facing each other in the thickness
direction of the mold and opposite polarities in the width
direction of the mold.
[0014] The first static magnetic field generator and the second
static magnetic field generator may be spaced by a first distance
from each other, and the third static magnetic field generator and
the fourth static magnetic field generator may be spaced by a
second distance from each other. Here, the first distance may be
the same as the second distance.
[0015] When the cast slab has an entire width of 100, each of the
first distance and the second distance may be in a range from 4 to
36.
[0016] At least one of the first static magnetic field generator,
the second static magnetic field generator, the third static
magnetic field generator, and the fourth static magnetic field
generator may be movable along the width direction of the mold.
[0017] The casting apparatus may further include: a first
connection core configured to connect the first static magnetic
field generator and the second static magnetic field generator; and
a second connection core configured to connect the third static
magnetic field generator and the fourth static magnetic field
generator.
[0018] The static magnetic field generation unit may form a
magnetic field that rotates in a circumferential direction of the
mold.
[0019] The casting apparatus may further include a dynamic magnetic
field generation unit disposed above the static magnetic field
generation unit to form a dynamic magnetic field for controlling a
flow of the molten material, and the control unit may control an
operation of the dynamic magnetic field generation unit so as to
adjust at least one of an intensity and a direction of the dynamic
magnetic field.
[0020] The dynamic magnetic field generation unit may include a
plurality of dynamic magnetic field generators configured to form a
dynamic magnetic field at both sides of the nozzle in the width
direction of the mold.
[0021] The dynamic magnetic field generation unit may be disposed
in parallel to the static magnetic field generation unit and
control the flow of the molten material in a direction different
from the static magnetic field generation unit.
[0022] In accordance with another exemplary embodiment, a casting
method includes: injecting a molten material into a mold by using a
nozzle; forming a static magnetic field applied region and a
non-static magnetic field applied region in a width direction of
the mold and controlling a flow of the molten material in a
longitudinal direction of the mold; and drawing a cast slab.
[0023] The casting method may further include, before the injecting
of the molten material, arranging the nozzle at a central portion
in the width direction of the mold, and the controlling of the flow
of the molten material may include forming the non-static magnetic
field applied region at a central portion in the width direction of
the mold and forming the static magnetic field applied region at
both sides of the non-static magnetic field applied region.
[0024] The controlling of the flow of the molten material may
include forming the static magnetic field applied region and the
non-static magnetic field applied region below the nozzle.
[0025] The controlling of the flow of the molten material may
include forming a magnetic field along a thickness direction of the
mold, and the forming of the static magnetic field applied region
may include forming a static magnetic field so that magnetic fields
at both sides of the nozzle have opposite directions.
[0026] The controlling of the flow of the molten material may
include forming the non-static magnetic field applied region at a
portion of the central portion in the width direction of the mold,
at which the nozzle is disposed.
[0027] The controlling of the flow of the molten material may
include controlling a range of the static magnetic field applied
region so that the non-static magnetic field applied region has a
magnetic field of 0 Gauss to 100 Gauss.
[0028] The controlling of the flow of the molten material may
include adjusting a distance between the static magnetic field
applied regions according to a width of the cast slab.
[0029] The controlling of the flow of the molten material may
include forming the static magnetic field applied region at both
edges in the width direction of the mold to reduce a flow velocity
of a downflow of the molten material and forming the non-static
magnetic field applied region between the static magnetic field
applied regions to form an upflow of the molten material.
[0030] The controlling of the flow of the molten material may
further include forming a dynamic magnetic field applied region and
a non-dynamic magnetic field applied region to control the flow of
the molten material in the width direction of the mold.
[0031] The controlling of the flow of the molten material in the
width direction of the mold may include forming a dynamic magnetic
field applied region and a non-dynamic magnetic field applied
region between a molten surface of the molten material and a lower
end of the nozzle.
[0032] The forming of the dynamic magnetic field applied region may
include forming a dynamic magnetic field in the width direction of
the mold at both sides of the nozzle in the width direction of the
mold.
[0033] The forming of the dynamic magnetic field applied region may
include adjusting at least one of an intensity and a direction of
the dynamic magnetic field.
Advantageous Effects
[0034] In accordance with the exemplary embodiment, the flow of the
molten material in the container may be locally controlled. That
is, the flow of the molten material in the longitudinal direction
of the mold may be selectively controlled by selectively applying
the static magnetic field in the width direction of the mold. Thus,
the inclusion contained in the molten material may have the reduced
downward movement distance along the molten material and
simultaneously easily float upward to restrict the quality
degradation of the product caused by the inclusion. Also, as the
dynamic magnetic field is formed in the width direction of the
mold, the flow of the molten material around the molten surface of
the molten material may be controlled to restrict the different
kind of material such as the mold flux or the mold slag from being
mixed with the molten material. Through this, the cleanliness of
the molten material may be secured, and the quality of the product
manufactured by using the molten material may be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a perspective view illustrating a casting
apparatus in accordance with an exemplary embodiment.
[0036] FIG. 2 is a cross-sectional view illustrating the casting
apparatus taken along line A-A' of FIG. 1.
[0037] FIG. 3 is a view for explaining a principle of controlling a
flow of a molten material by using a static magnetic field
generator.
[0038] FIG. 4 is a cross-sectional view illustrating a casting
apparatus in accordance with a modified example.
[0039] FIG. 5 is a view illustrating a state of controlling a flow
of a molten material by a casting method in accordance with an
exemplary embodiment.
[0040] FIG. 6 is a view illustrating a flow analysis result of a
secondary upflow in a mold according to whether a non-static
magnetic field applied region is formed in a width direction of the
mold.
[0041] FIG. 7 is a cross-sectional view illustrating the casting
apparatus taken along line B-B' of FIG. 1.
[0042] FIG. 8 is a view illustrating an example of controlling a
flow of a molten material by using a dynamic magnetic field
generator.
MODE FOR CARRYING OUT THE INVENTION
[0043] Hereinafter, specific embodiments will be described in more
detail with reference to the accompanying drawings. The present
invention may, however, be embodied in different forms and should
not be construed as limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the scope of the
present invention to those skilled in the art. In every possible
case, like reference numerals are used for referring to the same or
similar elements in the description and drawings. In the figures,
the dimensions of layers and regions are exaggerated for clarity of
illustration. Like reference numerals in the drawings denote like
elements, and thus their description will be omitted.
[0044] FIG. 1 is a perspective view illustrating a casting
apparatus in accordance with an exemplary embodiment, and FIG. 2 is
a cross-sectional view taken along line A-A' of FIG. 1.
[0045] Referring to FIGS. 1 and 2, the casting apparatus in
accordance with an exemplary embodiment may include: a mold 100
providing a space for accommodating a molten material therein; a
nozzle 130 having at least a portion inserted into the mold 100 to
supply the molten material to the mold 100; a static magnetic field
generation unit 200 provided on an outside in a width direction of
the mold 100 to control a direction of a magnetic field in
different directions at both edges in the width direction of the
mold 100; and a control unit 400 capable of controlling an
operation of the static magnetic field generation unit 200.
[0046] The mold 100 may include a plurality of plates 110 and 120
for providing a space for accommodating a molten material, e.g.,
molten steel, therein. Here, the plurality of plates 110 and 120
may include long side plates 110 and short side plates 120.
[0047] The long side plates 110, e.g., a first long side plate 111
and a second long side plate 113, may be spaced apart from each
other to face each other, and the short side plates 120, e.g., a
first short side plate 121 and a second short side plate 123, may
contact both sides of each of the first long side plate 111 and the
second long side plate 113 to form a space for accommodating a
molten material therein. Here, upper and lower portions of the mold
100 may be opened, and the long side plates 110 and the short side
plates 120 may closely contact each other to prevent the molten
material from being leaked through a contact portion thereof.
[0048] Here, a length in a horizontal direction of each of the long
side plates 110 is referred to as a width the of long side plate
110, and a direction of the width is referred to as a width
direction of the long side plate 110. Here, the width direction of
the long side plate 110 may represent a width direction of the mold
100. Here, a length in a vertical direction of the long side plate
110 is referred to as a length the of long side plate 110, and a
direction of the length is referred to as a longitudinal direction
of the long side plate 110. Here, the longitudinal direction of the
long side plate 110 may represent a longitudinal direction of the
mold 100 or a drawing direction of a cast slab. Also, a length in a
horizontal direction of each of the short side plates 120 is
referred to as a width the of short side plate 120, and a direction
of the width is referred to as a width direction of the short side
plate 120. Here, the width direction of the short side plate 120
may represent a width direction of the mold 100.
[0049] As a flow path (not shown) through which a cooling medium
moves is formed in each of the long side plate 110 and the short
side plate 120, the molten material injection to the mold may be
cooled by the cooling medium moving along the flow path. Thus, the
molten material may be solidified from a portion contacting an
inner surface of the mold 100 to be cast into a solidified cell or
a cast slab, and drawn to a lower portion of the mold 100.
[0050] The nozzle 130 may be disposed at an upper portion of the
mold 100 to inject the molten material into the mold 100. The
nozzle 130 may have at least a portion, e.g., a lower portion,
inserted into the mold 100 to inject the molten material
accommodated in a tundish (not shown) disposed above the mold 100
into the mold 100. The nozzle 130 may include a nozzle body 132
having an inner empty part through which the molten material moves
and a discharge hole 134 through which the molten material moves
from the inner hole part to the outside, i.e., the mold 100. Here,
the nozzle body 132 may have an opened upper portion and a closed
lower end, and the inner empty part (not shown) may be defined in
the nozzle body 132 to form a path through which the molten
material moves. Also, at least two discharge holes 134, e.g., two
or four discharge holes, may be defined in a lower side surface of
the nozzle body 132 to discharge the molten material into the mold
100. Here, the discharge hole 134 may be formed in the lower side
surface of the nozzle body 132, which faces the short side plate
120, to discharge the molten material in the width direction of the
mold 100.
[0051] The static magnetic field generation unit 200 may be
disposed at an outside in the width direction of the mold 100 and
apply a magnetic field, e.g., a static magnetic field, to the
molten material. Here, the static magnetic field generation unit
200 may be disposed below a lower end of the nozzle 130 to control
a flow of a downflow of the molten material discharged from the
discharge hole 134. Also, the static magnetic field generation unit
200 may be formed at each of both edges in the width direction of
the mold 100, in which the downflow is formed, to form a static
magnetic field applied region. The static magnetic field generation
unit 200 may apply a static magnetic field in the width direction
of the mold 100 to reduce a flow velocity of the downflow of the
molten material, which is formed at the edge in the width direction
of the mold 100. Here, the static magnetic field may be formed by
using a direct current power in a magnetic field generator and
reduce a flow velocity of fluid by restricting an overall movement
or flow of fluid in a magnetic field region. When the static
magnetic field is applied by the static magnetic field generation
unit 200, a movement of the downflow may be restricted by the
static magnetic field to reduce the flow velocity of the downflow.
Thus, as a movement distance of an inclusion in a downward
direction is reduced, a penetration depth of the inclusion in the
molten material may decrease.
[0052] Even in the related art, a method of controlling the
downflow by installing the static magnetic field generation unit in
the mold is used. In this case, since the static magnetic field
generation unit is installed in the mold to apply the static
magnetic field along the entire width direction of the mold, the
flow velocity of the downflow may be reduced. However, as the flow
of the molten material is restricted by the magnetic field formed
along the entire width direction of the mold, a secondary upflow
may be also reduced to allow the inclusion contained in the molten
material to float upward.
[0053] Thus, in accordance with an exemplary embodiment, as a
static magnetic field applied region and a non-static magnetic
field applied region are selectively formed along the width
direction of the mold 100 by using the static magnetic field
generation unit 200, the flow velocity of the downflow may be
reduced by using the static magnetic field in the static magnetic
field applied region, and the secondary upflow may be formed by
minimizing an effect of the static magnetic field in the non-static
magnetic field applied region.
[0054] The static magnetic field generation unit 200 may form the
static magnetic fields at both sides in the width direction of the
mold 100 in different directions, e.g., opposite directions, in a
thickness direction of the mold 100. Thus, the static magnetic
field generation unit 200 may form the static magnetic field
applied region at both the edge in the width direction of the mold
100 and form a region in which an intensity of the magnetic field
formed in the static magnetic field applied region is offset, i.e.,
the non-static magnetic field applied region, at a central portion
in the width direction of the mold 100. Thus, since an inclusion
having a reduced penetration depth in the static magnetic field
applied region may easily float upward by the secondary upflow
formed in the non-static magnetic field applied region, a defect of
a surface of the cast slab caused by the including may be
restricted.
[0055] The static magnetic field generation unit 200 may reduce the
flow velocity of the downflow formed in the longitudinal direction
of the mold at both the edges in the width direction of the mold
100, in which the static magnetic field applied region is formed,
and increase the flow velocity of the secondary upflow formed in
the longitudinal direction of the mold or allow the secondary
upflow to be smoothly formed at the central portion in the width
direction of the mold 100, in which the non-static magnetic field
applied region is formed.
[0056] Here, the static magnetic field applied region, as a region
in which the static magnetic field or the magnetic field is formed
by the static magnetic field generation unit 200, may represent a
region in which the static magnetic field or the magnetic field
having an intensity capable of causing the flow of the molten
material is applied. Also, the non-static magnetic field applied
region may represent a region in which the static magnetic field or
the magnetic field having an intensity that is not affected to the
flow of the molten material is applied or a region in which the
static magnetic field or the magnetic field is not applied at all.
For example, the non-static magnetic field applied region may
represent a region in which the static magnetic field or the
magnetic field having an intensity of 0 Gauss to 100 Gauss is
applied.
[0057] Referring to FIG. 2, the static magnetic field generation
unit 200 may include a plurality of static magnetic field
generators 210, 220, 230, and 240 disposed in the width direction
of the long side plate 110 below the lower end of the nozzle 130
and a first direct current supplier 250 for supplying a direct
current to the plurality of static magnetic field generators 210,
220, 230, and 240.
[0058] The plurality of static magnetic field generators 210, 220,
230, and 240 may include a first static magnetic field generator
210, a second static magnetic field generator 220 spaced apart from
the first static magnetic field generator 210 so that the nozzle
130 is disposed between the first static magnetic field generator
210 and the second static magnetic field generator 220, a third
static magnetic field generator 230 disposed to face the second
static magnetic field generator 220, and a fourth static magnetic
field generator 240 spaced apart from the third static magnetic
field generator 230 so that the nozzle 130 is disposed between the
third static magnetic field generator 230 and the fourth static
magnetic field generator 240 and disposed to face the first static
magnetic field generator 210. The first static magnetic field
generator 210 and the second static magnetic field generator 220
may be spaced apart from each other on an outer surface of the
first long side plate 111, and the third static magnetic field
generator 230 and the fourth static magnetic field generator 240
may be spaced apart from each other on an outer surface of the
second long side plate 113. Here, a spaced distance D between the
first static magnetic field generator 210 and the second static
magnetic field generator 220, e.g., a first distance, may be the
same as a spaced distance D between the third static magnetic field
generator 230 and the fourth static magnetic field generator 240,
e.g., a second distance. This allows the non-static magnetic field
applied region to be formed at the central portion in the width
direction of the mold 100. Each of the first distance and the
second distance may be varied based on a width of the cast slab to
be cast. When an entire width of the cast slab is 100, each of the
first distance and the second distance may be adjusted in a range
from 4 to 36. Alternatively, when the entire width of the cast slab
is 100, each of the first distance and the second distance may be
adjusted in a range from 10 to 25 or in a range from 15 to 20.
Here, when each of the first distance and the second distance is
much less than the suggested range, a space for forming the
secondary upflow may be sufficiently secured. Since the secondary
upflow is almost not formed or formed in a relatively small region
although the secondary upflow is formed, the inclusion contained in
the molten material may not be sufficiently removed. On the other
hand, when each of the first distance and the second distance is
much greater than the suggested range, the downflow having a
reduced flow velocity may not sufficiently move from both the edges
in the width direction of the mold 100 to the central portion of
the mold 100, and accordingly the flow velocity of the secondary
upflow may be also reduced, so that the inclusion is difficult to
float upward.
[0059] Thus, as each of the first static magnetic field generator
210, the second static magnetic field generator 220, the third
static magnetic field generator 230, and the fourth static magnetic
field generator 240 is movable in the width of the mold 100, each
of the first distance and the second distance may be appropriately
adjusted based on the width of the cast slab to effectively
removing the inclusion contained in the molten material. Here, the
first distance and the second distance may be affected by a casting
speed. For example, when the width of the cast slab is 1100 mm or
less, and the casting speed is in a range from 0.7 m/min to 2.8
m/min, each of the first distance and the second distance may be
adjusted in a range from 50 mm to 250 mm. Also, when the width of
the cast slab is in a range from 1100 mm to 1500 mm, and the
casting speed is in a range from 0.7 m/min to 2.8 m/min, each of
the first distance and the second distance may be adjusted in a
range from 100 mm to 350 mm, and when the width of the cast slab is
in a range from 1500 mm to 1900 mm, and the casting speed is in a
range from 0.7 m/min to 2.8 m/min, each of the first distance and
the second distance may be adjusted in a range from 100 mm to 500
mm
[0060] Firstly, the first static magnetic field generator 210 may
be biased to one side of the first long side plate 111, and the
second static magnetic field generator 220 may be spaced apart from
the first static magnetic field generator 210 and biased to the
other side of the first long side plate 111. Here, the first static
magnetic field generator 210 may include a first core 212 and a
first coil 214 wound around an outside of the first core 212. The
second static magnetic field generator 220 may include a second
core 222 and a second coil 224 wound around an outside of the
second core 222. Here, one side of the mold 100 or one side of the
long side plate 110 may represent a direction in which the first
short plate 121 is disposed, and the other side of the mold 100 or
the other side of the long side plate 110 may represent a direction
in which the second short plate 123 is disposed.
[0061] The first core 212 and the second core 222 may be disposed
on an outside of the mold 100 and spaced apart from each other in
the width direction of the mold 100. Each of the first core 212 and
the second core 222 may have a plate shape extending in one
direction. For example, each of the first core 212 and the second
core 222 may have a plate shape in which a length in the width
direction of the mold 100 is greater than that in the thickness
direction of the mold 100. The first core 212 and the second core
222 may be arranged in a row on an outer surface of the first long
side plate 111 to each extend along a portion of the width
direction of the first long side plate 111. Here, the first core
212 and the second core 222 may be spaced apart from the central
portion in the width direction of the mold 100 in which the nozzle
130 is disposed so that the nozzle 130 is disposed
therebetween.
[0062] Also, the first coil 214 may be wound around the outside of
the first core 212 in a direction in which the first core 212
extends, e.g., the width direction of the mold 100. Also, the
second coil 224 may be wound around the outside of the second core
222 in a direction in which the second core 222 extends, e.g., a
horizontal direction in the width direction of the mold 100.
[0063] Also, the third static magnetic field generator 230 may be
biased to the other side of the second long side plate 113, and the
fourth static magnetic field generator 240 may be spaced apart from
the third static magnetic field generator 230 and biased to the one
side of the second long side plate 113. Here, the third static
magnetic field generator 230 may be disposed at a position facing
the second static magnetic field generator 220, e.g., disposed to
face the second static magnetic field generator 220, and the fourth
static magnetic field generator 240 may be disposed to face the
first static magnetic field generator 210. The third static
magnetic field generator 230 may include a third core 232 and a
third coil 234 wound around an outside of the third core 232. The
fourth static magnetic field generator 240 may include a fourth
core 242 and a fourth coil 244 wound around an outside of the
fourth core 242. The third core 232 and the fourth core 242 may be
disposed on an outside of the mold 100 and spaced apart from each
other in the width direction of the mold 100. The third core 232
and the fourth core 242 may be arranged in a row on an outer
surface of the second long side plate 113 to each extend along a
portion of a width direction of the second long side plate 113.
Here, the third core 232 and the fourth core 242 may be spaced
apart from the central portion in the width direction of the mold
100 in which the nozzle 130 is disposed so that the nozzle 130 is
disposed therebetween.
[0064] Also, the third coil 234 may be wound around the outside of
the third core 232 in the width direction of the mold 100 that is a
direction in which the third core 232 extends. Also, the fourth
coil 244 may be wound around the outside of the fourth core 222 in
the width direction of the mold 100 that is a direction in which
the fourth core 242 extends.
[0065] The first static magnetic field generator 210, the second
static magnetic field generator 220, the third static magnetic
field generator 230, and the fourth static magnetic field generator
240 may be electrically connected with the first direct current
supplier 250. The first direct current supplier 250 may supply a
direct current to the first static magnetic field generator 210,
the second static magnetic field generator 220, the third static
magnetic field generator 230, and the fourth static magnetic field
generator 240. The first direct current supplier 250 may supply the
direct current simultaneously or selectively to the first static
magnetic field generator 210, the second static magnetic field
generator 220, the third static magnetic field generator 230, and
the fourth static magnetic field generator 240 through control of
the control unit 400. The first direct current supplier 250 may
supply the direct current to each of the first static magnetic
field generator 210, the second static magnetic field generator
220, the third static magnetic field generator 230, and the fourth
static magnetic field generator 240 so that a magnetic field
direction is formed in the thickness direction of the mold 100.
Here, the first direct current supplier 250 may supply the direct
current so that the magnetic field directions are formed in
opposite directions at the central portion in the width direction
of the mold 100, e.g., at both the sides of the nozzle 130. That
is, the first direct current supplier 250 may supply the direct
current to the first static magnetic field generator 210, the
second static magnetic field generator 220, the third static
magnetic field generator 230, and the fourth static magnetic field
generator 240 so that the magnetic field direction is formed from
the first static magnetic field generator 210 to the fourth static
magnetic field generator 240 at the one side of the mold 100, and
the magnetic field direction is formed from the third static
magnetic field generator 230 to the second static magnetic field
generator 220 at the other side of the mold 100. Here, the control
unit 400 may control the first direct current supplier 250 to
adjust a current amount supplied to each of the first static
magnetic field generator 210, the second static magnetic field
generator 220, the third static magnetic field generator 230, and
the fourth static magnetic field generator 240 in order to adjust
an intensity or a strength of the magnetic field.
[0066] Here, the magnetic field direction formed at one side of the
nozzle 130 in the width direction of the mold 100, e.g., the one
side of the mold 100, is referred to as a first direction, and the
magnetic field direction formed at the other side of the nozzle 130
in the width direction of the mold 100, e.g., the other side of the
mold 100, is referred to as a second direction. For example, the
magnetic field direction formed between the first static magnetic
field generator 210 and the fourth static magnetic field generator
240 is referred to as the first direction, and the magnetic field
direction formed between the second static magnetic field generator
220 and the third static magnetic field generator 230 is referred
to as the second direction. Here, the first direction and the
second direction may be opposite to each other. Also, in each of
the first core 212, the second core 222, the third core 232, and
the fourth core 242, a direction facing the mold 100 is referred to
as one side, and a direction facing the outside of the mold 100 is
referred to as the other side. Thus, the first current supplier 250
may supply the direct current so that one side of the first core
212 and one side of the fourth core 242, which face each other,
have opposite polarities. Also, the first current supplier 250 may
supply the direct current so that one side of the second core 222
and one side of the third core 232, which face each other, have
opposite polarities. Here, the first current supplier 250 may
supply the direct current so that so that one side of the first
core 212 and one side of the second core 222 have opposite
polarities, and one side of the third core 232 and one side of the
fourth core 242 have opposite polarities.
[0067] For example, the first current supplier 250 may supply the
direct current so that each of one side of the first core 212 and
one side of the third core 232 has an N pole, and each of one side
of the second core 222 and one side of the fourth core 242 has a S
pole. In this case, when the first current supplier 250 supplies
the direct current to each of the static magnetic field generators
210, 220, 230, and 240, a static magnetic field may be formed in
each of the static magnetic field generators 210, 220, 230, and
240. The static magnetic field having a magnetic field direction
heading from the S pole to the N pole may be formed in each of the
static magnetic field generators 210, 220, 230, and 240. Here, the
static magnetic field generated in the first static magnetic field
generator 210 may have a magnetic field direction heading from the
other side of the first core 212 and one side of the first core
212, and the static magnetic field generated in the fourth static
magnetic field generator 240 may have a magnetic field direction
heading from one side of the fourth core 242 and the other side of
the fourth core 242. The magnetic field having a direction from the
first static magnetic field generator 210 to the fourth static
magnetic field generator 240, e.g., the first direction, may be
formed at one side of the mold 100. Also, the static magnetic field
generated in the third static magnetic field generator 230 may have
a magnetic field direction heading from the other side of the third
core 232 and one side of the third core 232, and the static
magnetic field generated in the second static magnetic field
generator 220 may have a magnetic field direction heading from one
side of the second core 222 and the other side of the second core
222. The magnetic field having a direction from the third static
magnetic field generator 230 to the second static magnetic field
generator 220, e.g., the second direction, may be formed at one
side of the mold 100. Here, although, herein, the first direction
heads from the first static magnetic field generator 210 to the
fourth static magnetic field generator 240, and the second
direction heads from the third static magnetic field generator 230
to the second static magnetic field generator 220, the first
direction and the second direction may be changed according to a
state of supplying the direct current from the first current
supplier 250 to each of the first static magnetic field generator
210, the second static magnetic field generator 220, the third
static magnetic field generator 230, and the fourth static magnetic
field generator 240. However, even in the case, the first direction
and the second direction may be opposite to each other.
[0068] FIG. 3 is a view for explaining a principle of controlling
the flow of the molten material by using the static magnetic field
generator.
[0069] Firstly, the molten material may be injected into the mold
100 by using the nozzle 130. Before the molten material is injected
into the mold 100, the nozzle 130 may be positioned at the central
portion in the width direction of the mold 100. Then, the cast slab
may be drawn while forming the static magnetic field applied region
and the non-static magnetic field applied region in the width
direction of the mold 100 and controlling the flow of the molten
material in the width direction of the mold 100. Here, the process
of forming the static magnetic field applied region and the
non-static magnetic field applied region in the width direction of
the mold 100 may be performed before the molten material is
injected into the mold 100, after the molten material is injected
into the mold 100, or simultaneously when molten material is
injected into the mold 100.
[0070] The flow of the molten material may be controlled as stated
below.
[0071] Referring to FIG. 3, when the direct current is supplied to
each of the first static magnetic field generator 210, the second
static magnetic field generator 220, the third static magnetic
field generator 230, and the fourth static magnetic field generator
240 through the first current supplier 250, each of the first
static magnetic field generator 210, the second static magnetic
field generator 220, the third static magnetic field generator 230,
and the fourth static magnetic field generator 240 may form the
magnetic field. Here, the first static magnetic field generator 210
and the third static magnetic field generator 230, which are
misaligned with respect to the nozzle 130, may have the same
polarity, and second static magnetic field generator 220 and the
fourth static magnetic field generator 240, which are misaligned
with respect to the nozzle 130, may also have the same polarity.
For example, one side of the first core 212 and one side of the
third core 232 may form the same polarity, e.g., the N pole, and
one side of the second core 222 and one side of the fourth core 242
may form the same polarity, e.g., the S pole. Also, the static
magnetic field formed in each of the static magnetic field
generators 210, 220, 230, and 240 has a magnetic field direction
heading from the S pole to the N pole according to the cores 212,
222, 232, and 242 thereof. Here, the magnetic field formed around
each of the cores 212, 222, 232, and 242 may have the magnetic
field direction heading from the S pole to the N pole, and the
magnetic field may be formed in the thickness direction of the mold
100 by the magnetic field direction of the magnetic field formed
around each of the cores 212, 222, 232, and 242. Also, the magnetic
field may have a magnetic field intensity that gradually decreases
in a direction away from each of the cores 212, 222, 232, and 242.
Thus, the magnetic field may be offset between the first static
magnetic field generator 210 and the fourth static magnetic field
generator 240, which face each other, to form a region in which the
magnetic field is not applied or the magnetic field intensity is
extremely weak. This is because the one side of the first core 212
and the one side of the fourth core 242 have opposite polarities.
Also, the region in which the magnetic field is not applied or the
magnetic field intensity is extremely weak may be also formed
between the second static magnetic field generator 220 and the
third static magnetic field generator 230, which face each other.
This is because the one side of the second core 222 and the one
side of the third core 232 have opposite polarities. Also, the
region in which the magnetic field is not applied or the magnetic
field intensity is extremely weak may be also formed between the
first static magnetic field generator 210 and the second static
magnetic field generator 220 and between the third static magnetic
field generator 230 and the fourth static magnetic field generator
240. Thus, the region in which the magnetic field is not applied or
the magnetic field intensity is extremely weak, i.e., the
non-static magnetic field applied region, may be formed between the
static magnetic fields generated from the first static magnetic
field generator 210, the second static magnetic field generator
220, the third static magnetic field generator 230, and the fourth
static magnetic field generator 240, e.g., the central portion in
the thickness direction of the mold 100 and the central portion in
the width direction of the mold 100. Here, a feature in which the
magnetic field is not applied or the magnetic field intensity is
extremely weak may represent a case of the magnetic field intensity
in a range from 0 Gauss to 100 Gauss.
[0072] As described above, as the first static magnetic field
generator 210, the second static magnetic field generator 220, the
third static magnetic field generator 230, and the fourth static
magnetic field generator 240 are installed on the outside of the
mold 100, the static magnetic field applied region may be formed in
the region in which each of the first static magnetic field
generator 210, the second static magnetic field generator 220, the
third static magnetic field generator 230, and the fourth static
magnetic field generator 240 is disposed, and the non-static
magnetic field applied region may be selectively formed between the
first static magnetic field generator 210, the second static
magnetic field generator 220, the third static magnetic field
generator 230, and the fourth static magnetic field generator 240.
Thus, the flow velocity of the downflow of the molten material may
be reduced by using the magnetic field in the static magnetic field
applied region, and the secondary upflow may be smoothly formed by
minimizing effects of the magnetic field in the non-static magnetic
field applied region. Here, a width of the non-static magnetic
field applied region may be adjusted according to a width of the
cast slab to be cast. As described above, the secondary upflow may
be smoothly formed by adjusting the width of the non-static
magnetic field applied region according to the width of the cast
slab.
[0073] As the example in which the first core 212 and the second
core 222, and the third core 232 and the fourth core 242 are spaced
apart from each other in the width direction of the mold 100
herein, the example of forming the non-static magnetic field
applied region and the static magnetic field applied region in the
width direction of the mold 100 is described. However, the
non-static magnetic field applied region and the static magnetic
field may be formed in the thickness direction of the mold 100.
[0074] FIG. 4 is a cross-sectional view illustrating a casting
apparatus in accordance with a modified example. The casting
apparatus in accordance with a modified example may have almost the
structure as the above-described casting apparatus in accordance
with an exemplary embodiment except that a first static magnetic
field generator 210 and a second static magnetic field generator
220 is connected by a first connection core 272, and a third static
magnetic field generator 230 and a fourth static magnetic field
generator 240 is connected by a second connection core 274.
[0075] The first connection core 272 may connect a first core 212
of the first static magnetic field generator 210 and a second core
222 of the second static magnetic field generator 220 in a width
direction of a mold 100. Here, the first connection core 272 may
connect the other side of the first core 212 and the other side of
the second core 222 and be spaced apart from an outer surface of a
first long side plate 111 of the mold 100. The second connection
core 274 may connect a third core 232 of the third static magnetic
field generator 230 and a fourth core 242 of the fourth static
magnetic field generator 240 in the width direction of the mold
100. Here, the second connection core 274 may connect the other
side of the third core 232 and the other side of the fourth core
242 and be spaced apart from an outer surface of a second long side
plate 113 of the mold 100.
[0076] As described above, when the first core 212 and the second
core 222 are connected by the first connection core 272, the third
core 232 and the fourth core 242 are connected by the second
connection core 274, and a direct current is supplied to the third
static magnetic field generator 230 and the fourth static magnetic
field generator 240, a static magnetic field may be formed in each
of the first static magnetic field generator 210, the second static
magnetic field generator 220, the third static magnetic field
generator 230, and the fourth static magnetic field generator 240.
In this case, the static magnetic field may be formed in the width
direction of the mold 100 at an outside of the mold 100, and the
static magnetic field may be formed along a thickness direction of
the mold 100. For example, a S pole may be formed at one side of
each of the first core 212 and the third core 232, and a N pole may
be formed at one side of each of the second core 222 and the fourth
core 242. In this case, the static magnetic field formed in each of
the static magnetic field generators 210, 220, 230, and 240 has a
magnetic field direction heading from the S pole to the N pole
according to each of the cores 212, 222, 232, and 242 thereof.
Here, the magnetic field formed around each of the cores 212, 222,
232, and 242 may have the magnetic field direction heading from the
S pole to the N pole, and the magnetic field may be formed in the
thickness direction of the mold 100 by the magnetic field direction
of the magnetic field formed around each of the cores 212, 222,
232, and 242. The magnetic field having a magnetic field direction
heading from the fourth static magnetic field generator 240 to the
first static magnetic field generator 210 and the magnetic field
having a magnetic field direction heading from the second static
magnetic field generator 220 to the third static magnetic field
generator 230 may be formed in the thickness direction of the mold
100. Also, the magnetic field may have a magnetic field intensity
that gradually decreases in a direction away from each of the cores
212, 222, 232, and 242. Thus, the magnetic field may be offset
between the first static magnetic field generator 210 and the
fourth static magnetic field generator 240, which face each other,
to form a region in which the magnetic field is not applied or the
magnetic field intensity is extremely weak. This is because the one
side of the first core 212 and the one side of the fourth core 242
have opposite polarities.
[0077] Also, the region in which the magnetic field is not applied
or extremely weak may be also formed between the second static
magnetic field generator 220 and the third static magnetic field
generator 230, which face each other. This is because the one side
of the second core 222 and the one side of the third core 232 have
opposite polarities. Also, the region in which the magnetic field
is not applied or the magnetic field intensity is extremely weak
may be also formed between the first static magnetic field
generator 210 and the second static magnetic field generator 220
and between the third static magnetic field generator 230 and the
fourth static magnetic field generator 240. Thus, the region in
which the magnetic field is not applied or the magnetic field
intensity is extremely weak, i.e., the non-static magnetic field
applied region, may be formed between the static magnetic fields
generated from the first static magnetic field generator 210, the
second static magnetic field generator 220, the third static
magnetic field generator 230, and the fourth static magnetic field
generator 240, e.g., the central portion in the thickness direction
of the mold 100 and the central portion in the width direction of
the mold 100.
[0078] In addition, the static magnetic field having the magnetic
field direction heading from the first static magnetic field
generator 210 to the second static magnetic field generator 220 may
be formed on the first connection core 272 connecting the first
core 212 and the second core 222, and the static magnetic field
having the magnetic field direction heading from the third static
magnetic field generator 220 to the fourth static magnetic field
generator 240 may be formed on the second connection core 274.
Here, the magnetic fields formed on the first connection core 272
and the second connection core 274 may have opposite magnetic field
directions.
[0079] Thus, the magnetic field direction may rotate along the
width direction and the thickness direction of the mold 100. Thus,
a region in which the magnetic field is not applied or the magnetic
field intensity is extremely weak in the width direction of the
mold 100 may be formed between the static magnetic fields formed at
both sides in the width direction of the mold 100. Also, a region
in which the magnetic field is not applied or the magnetic field
intensity is extremely weak in the thickness direction of the mold
100 may be formed between the static magnetic fields formed at both
sides in the thickness direction of the mold 100. Thus, the region
in which the magnetic field is not applied or the magnetic field
intensity is extremely weak, i.e., the non-static magnetic field
applied region, may be formed at a position at which a region
contacting the magnetic field formed in the thickness direction of
the mold 100 and a region contacting the magnetic field formed in
the width direction of the mold 100 cross each other, e.g., a
central portion of the mold 100.
[0080] FIG. 5 is a view illustrating a state of controlling a flow
of a molten material by a casting method in accordance with an
exemplary embodiment.
[0081] Here, (a) of FIG. 5 is a view illustrating a flow state of
the molten material in a mold 100 before a flow of each of a
downflow and a secondary upflow is controlled by using a static
magnetic field generation unit 200, (b) of FIG. 5 is a view
illustrating a flow state of the molten material when a static
magnetic field is applied along an entire width direction of the
mold 100, and (c) of FIG. 5 is a view illustrating a flow state of
the molten material when a static magnetic field applied region and
a non-static magnetic field applied region are formed along the
width direction of the mold 100 by using the static magnetic field
generation unit 200.
[0082] A discharge flow of a molten material M discharged through a
discharge hole 134 of a nozzle 130 may collide both inner surfaces
of the mold 100 in the width direction of the mold 100 and then
form an upflow and a downflow. In FIG. 5, a reference symbol MF may
represents a mold flux, and a reference symbol MS may represent a
mold slag obtained as the mold flux is melted.
[0083] Referring to (a) of FIG. 5, it may be known that when a flow
of the molten material is not controlled by using the static
magnetic field generation unit 200, a movement distance, i.e., a
penetration depth, of an inclusion is deep because the downflow has
a relatively fast flow velocity. In this case, since the flow of
the molten material is not controlled by using the static magnetic
field generation unit 200, the secondary upflow may be smoothly
formed. However, since the inclusion contained in the molten
material moves far along a longitudinal direction of the mold 100,
i.e., a drawing direction of a cast slab, by the downflow, the
inclusion may not sufficiently float by the secondary upflow, and
thus a large amount of inclusions are still remained.
[0084] Referring to (b) of FIG. 5, it may be known that when the
magnetic field is applied along the entire width direction of the
mold 100, a flow velocity of the downflow is reduced by the
magnetic field, and a downward movement distance of the inclusion
becomes short. Also, since the secondary upflow is not properly
formed as the formation of the secondary upflow is restricted by
the magnetic field, the including moving by the downflow in the
longitudinal direction of the mold 100, i.e., the drawing direction
of the cast slab, may not float upward and stay in the molten
material.
[0085] However, referring to (c) of FIG. 5, it may be known that
when the flow of the molten material is controlled by using the
static magnetic field generation unit 200, the flow velocity of the
downflow is reduced at both sides in the width direction of the
mold 100, and the downward movement distance of the inclusion
becomes short. Also, as the non-static magnetic field applied
region is formed at the central portion in the width direction of
the mold 100 that is the non-static magnetic field applied region,
the secondary upflow may be sufficiently formed, and the inclusion
contained in the molten material may smoothly float upward and be
removed.
[0086] FIG. 6 is a view illustrating a flow analysis result of the
secondary upflow in the mold according to whether the non-static
magnetic field applied region is formed in the width direction of
the mold. Here, (a) of FIG. 6 is a view illustrating a flow state
of the molten material when the static magnetic field is applied to
the entire width direction of the mold, and (b) of FIG. 6 is a view
illustrating a flow state of the molten material when the
non-static magnetic field applied region is formed at the central
portion in the width direction of the mold.
[0087] Referring to (a) of FIG. 6, it may be known that when the
static magnetic field is applied to the entire width direction of
the mold, the secondary upflow is almost not formed. However,
referring to (b) of FIG. 6, it may be known that when the
non-static magnetic field applied region is formed at the central
portion in the width direction of the mold, the secondary upflow is
smoothly formed at the central portion in the width direction of
the mold, to which the static magnetic field is not applied.
[0088] As described above, as the static magnetic field applied
region and the non-static magnetic field applied region are
selectively formed along the width direction of the mold, the flow
of the molten material in the mold may be locally controlled to
secure a clearness of the molten material. Also, the cast slab that
is cast by using the above-described molten material may have an
improved quality.
[0089] The casting apparatus in accordance with an exemplary
embodiment may include a dynamic magnetic field generation unit 300
disposed above the static magnetic field generation unit 200 at the
outside of the mold 100 in order to control the flow of the molten
material above the static magnetic field generation unit 200. Here,
the control unit 400 may control an operation of the dynamic
magnetic field generation unit 300 to adjust at least one of an
intensity and a direction of a dynamic magnetic field.
[0090] A portion of the molten material discharged from the nozzle
130 may form an upflow that collides with the short side plate 120
and then moves upward. Also, the upflow horizontally moves toward
the central portion in the width direction of the mold as a
movement direction of the upflow is changed around a molten surface
of the molten material. A flow of the molten material moving toward
the central portion in the width direction of the mold, e.g., a
horizontal directional flow, may collide with a flow of the molten
material moving from an opposite direction thereof to form a vortex
around the nozzle 130. Here, when the horizontal directional flow
has an extremely fast flow velocity, a different kind of material
such as the mold flux or the mold slag disposed on the molten
material may be mixed with the molten material. However, when the
horizontal directional flow has an extremely slow flow velocity,
the molten material in the mold 100 may have an ununiform
temperature. Thus, as the horizontal directional flow of the molten
material around the molten surface of the molten material is
controlled by using the dynamic magnetic field generation unit 300,
the different kind of material such as the mold flux or the mold
slag may be restricted from being mixed into the molten material,
and the temperature of the molten material in the mold 100 may be
uniformly controlled. The flow velocity of the horizontal
directional flow of the molten material may be affected by the flow
velocity of the molten material discharged through the discharge
hole 134 of the nozzle 130, i.e., the flow velocity of the
discharge flow. Thus, as the flow velocity of the discharge flow is
controlled by using the dynamic magnetic field generation unit 300,
the flow velocity of the horizontal directional flow of the molten
material formed around the molten surface of the molten material
may be controlled.
[0091] FIG. 7 is a cross-sectional view illustrating the casting
apparatus taken along line B-B' of FIG. 1.
[0092] The dynamic magnetic field generation unit 300 may be
disposed above the static magnetic field generation unit 200, e.g.,
disposed between the molten surface of the molten material and the
lower end of the nozzle 130, to control the flow of the molten
material in a direction different from the static magnetic field
generation unit 200. Referring to FIG. 7, the dynamic magnetic
field generation unit 300 may include a plurality of dynamic
magnetic field generators 310, 320, 330, and 340 spaced apart from
each other in the width direction of the long side plate and a
second current supplier 350 selectively supplying an alternating
current to the plurality of dynamic magnetic field generators. The
plurality of dynamic magnetic field generators 310, 320, 330, and
340 may include: a first dynamic magnetic field generator 310
disposed in parallel to the first static magnetic field generator
210 above the first static magnetic field generator 210; a second
dynamic magnetic field generator 320 spaced apart from the first
dynamic magnetic field generator 310 so that the nozzle 130 is
disposed therebetween and disposed in parallel to the second static
magnetic field generator 220 above the second static magnetic field
generator 220; a third dynamic magnetic field generator 330 facing
the second dynamic magnetic field generator 310 and disposed in
parallel to the third static magnetic field generator 230 above the
third static magnetic field generator 230; and a fourth dynamic
magnetic field generator 340 spaced apart from the third dynamic
magnetic field generator 330 so that the nozzle 130 is disposed
therebetween and disposed in parallel to the fourth static magnetic
field generator 240 above the fourth static magnetic field
generator 240. That is, the first dynamic magnetic field generator
310 and the second dynamic magnetic field generator 320 may be
disposed at the outside of the first long side plate 111 to form a
dynamic magnetic field applied region and a non-dynamic magnetic
field applied region in the width direction of the mold 100. Also,
the third dynamic magnetic field generator 330 and the fourth
dynamic magnetic field generator 340 may be disposed at the outside
of the second long side plate 113 to form a dynamic magnetic field
applied region and a non-dynamic magnetic field applied region in
the width direction of the mold 100. Each of the first dynamic
magnetic field generator 310, the second dynamic magnetic field
generator 320, the third dynamic magnetic field generator 330, and
the fourth dynamic magnetic field generator 340 may include a
plurality of cores and a coil wound around an outside of the core.
Each of the dynamic magnetic field generators 310, 320, 330, and
340 may include three, four, five, or more cores. Hereinafter, an
example in which each of the dynamic magnetic field generators 310,
320, 330, and 340 includes four cores will be described.
[0093] For example, the first dynamic magnetic field generator 310
may include a first core 312a, a second core 312b, a third core
312c, and a fourth core 312d, which are arranged in parallel in the
width direction of the mold 100, and a first coil 314a, a second
coil 314b, a third coil 314c, and a fourth coil 314d, which are
respectively wound around the cores 312a, 312b, 312c, and 312d.
Also, the second current supplier 350 may be electrically connected
with the first coil 314a, the second coil 314b, the third coil
314c, and the fourth coil 314d and selectively supply an
alternating current to each of the coils 314a, 314b, 314c, and
314d. In this case, the second current supplier 350 may apply a
cosine type current to each of the coils 314a, 314b, 314c, and 314d
so that each of the coils 314a, 314b, 314c, and 314d has the S pole
and the N pole at a phase difference of 0.degree., 90.degree.,
180.degree., and 270.degree. as shown in table 1 below.
TABLE-US-00001 TABLE 1 First coil Second coil Third coil Fourth
coil 0.degree. S -- N -- 90.degree. -- S -- N 180.degree. N -- S --
270.degree. -- N -- S
[0094] Referring to table 1, when an alternating current power
having a phase of 0.degree. is supplied to the first coil 314a and
the third coil 314c, the first coil 314a may have the S pole, and
the third coil 314c may have the N pole. Also, when an alternating
current power having a phase of 90.degree. is supplied to the
second coil 314b and the fourth coil 314d, the second coil 314b may
have the S pole, and the fourth coil 314d may have the N pole. When
an alternating current power having a phase of 180.degree. is
supplied to the first coil 314a and the third coil 314c, the first
coil 314a may have the N pole, and the third coil 314c may have the
S pole. Also, when an alternating current power having a phase of
270.degree. is supplied to the second coil 314b and the fourth coil
314d, the second coil 314b may have the N pole, and the fourth coil
314d may have the S pole. When the alternating current power is
supplied to each of the coils as described above, the polarity of
each of the coils is periodically changed according to the phase of
the supplied alternating current. Thus, a magnetic field, i.e., a
dynamic magnetic field, moving in a direction in which the coils
are arranged, i.e., the width direction of the mold 100, may be
formed in the first dynamic magnetic field generator 310.
[0095] The dynamic magnetic field may be formed in each of the
second dynamic magnetic field generator 320, the third dynamic
magnetic field generator 330, and the fourth dynamic magnetic field
generator 340 in the same methods as the first dynamic magnetic
field generator 310. Thus, the dynamic magnetic field applied
region and the non-dynamic magnetic field applied region may be
formed along the width direction of the mold 100. In FIG. 7,
reference symbols 322a to 322d and 324a to 324d represent the core
and coil of the second dynamic magnetic field generator 320,
reference symbols 332a to 332d and 334a to 334d represent the core
and coil of the third dynamic magnetic field generator 330, and
reference symbols 342a to 342d and 344a to 344d represent the core
and coil of the fourth dynamic magnetic field generator 340.
[0096] The second current supplier 350 may supply an alternating
current to the first dynamic magnetic field generator 310, the
second dynamic magnetic field generator 320, the third dynamic
magnetic field generator 330, and the fourth dynamic magnetic field
generator 340 so that the magnetic field direction is formed in the
width direction of the mold 100. Here, the second current supplier
350 may control the horizontal directional flow formed by the
upflow by controlling the flow of the discharge flow in the mold
100. To this end, the second current supplier 350 may supply the
alternating current to the first dynamic magnetic field generator
310, the second dynamic magnetic field generator 320, the third
dynamic magnetic field generator 330, and the fourth dynamic
magnetic field generator 340 so that the magnetic field direction
is formed in the horizontal direction similar to the movement
direction of the discharge flow, i.e., the width direction of the
mold 100. In this case, the second current supplier 350 may supply
the alternating current so that at least a portion of the dynamic
magnetic field generators 310, 320, 330, and 340 form the dynamic
magnetic fields in different directions. For example, the second
current supplier 350 may supply the alternating current in order to
form the dynamic magnetic field on the first dynamic magnetic field
generator 310 and the second dynamic magnetic field generator 320,
which are disposed on the outside of the first long side plate 111,
in the same direction, e.g., in the third direction, and form the
dynamic magnetic field on the third dynamic magnetic field
generator 330 and the fourth dynamic magnetic field generator 340,
which are disposed on the outside of the second long side plate
113, in the same direction, e.g., in the fourth direction. Here,
the third direction and the fourth direction may be opposite to
each other. Alternatively, the second current supplier 350 may
supply the alternating current in order to form the dynamic
magnetic field on the first dynamic magnetic field generator 310
and the fourth dynamic magnetic field generator 340, which face
each other, in the same direction, e.g., in the third direction,
and form the dynamic magnetic field on the second dynamic magnetic
field generator 320 and the third dynamic magnetic field generator
330, which face each other, in the same direction, e.g., in the
fourth direction. Here, the magnetic field direction formed by each
of the first dynamic magnetic field generator 310, the second
dynamic magnetic field generator 320, the third dynamic magnetic
field generator 330, and the fourth dynamic magnetic field
generator 340 may be changed according to the flow velocity of the
discharge flow discharged from the discharge hole 134 of the nozzle
130.
[0097] FIG. 8 is a view illustrating an example of controlling the
flow of the molten material by using the dynamic magnetic field
generator. As illustrated in (a) of FIG. 8, when the discharge flow
has an extremely fast flow velocity, a flow velocity of a
horizontal directional flow around the molten surface of the molten
material becomes fast. In this case, the second current supplier
350 may supply the alternating current to the first dynamic
magnetic field generator 310, the second dynamic magnetic field
generator 320, the third dynamic magnetic field generator 330, and
the fourth dynamic magnetic field generator 340 so that the dynamic
magnetic field is formed in a direction opposite to the movement
direction of the discharge flow. Here, the second current supplier
350 may supply the alternating current to the first dynamic
magnetic field generator 310, the second dynamic magnetic field
generator 320, the third dynamic magnetic field generator 330, and
the fourth dynamic magnetic field generator 340 so that the dynamic
magnetic field direction is formed from the edge to the central
portion of the mold 100. Thus, as the flow velocity of the
discharge flow formed by being discharged from the discharge hole
134 of the nozzle 130 is reduced, the molten surface of the molten
material may be stably controlled.
[0098] On the other hand, as illustrated in (b) of FIG. 8, when the
discharge flow has an extremely slow flow velocity, the flow
velocity of the horizontal directional flow around the molten
surface of the molten material becomes slow. In this case, the
second current supplier 350 may supply the alternating current to
the first dynamic magnetic field generator 310, the second dynamic
magnetic field generator 320, the third dynamic magnetic field
generator 330, and the fourth dynamic magnetic field generator 340
so that the dynamic magnetic field is formed in the same direction
as the movement direction of the discharge flow. Here, the second
current supplier 350 may supply the alternating current to the
first dynamic magnetic field generator 310, the second dynamic
magnetic field generator 320, the third dynamic magnetic field
generator 330, and the fourth dynamic magnetic field generator 340
so that the dynamic magnetic field direction is formed from the
central portion to the edge of the mold 100. Accordingly, the flow
velocity of the discharge flow formed by being discharged from the
discharge hole 134 of the nozzle 130 may be accelerated to smoothly
form the flow such as the downflow, the upflow, and the secondary
upflow. Thus, the temperature of the molten material in the mold
100 may be uniformly controlled.
[0099] Also, the second current supplier 350 may supply the
alternating current to the first dynamic magnetic field generator
310, the second dynamic magnetic field generator 320, the third
dynamic magnetic field generator 330, and the fourth dynamic
magnetic field generator 340 in order to form the dynamic magnetic
field rotating in a circumferential direction of the mold 100. In
case of forming the dynamic magnetic field in the circumferential
direction of the mold 100, when the temperature of the molten
material around the molten surface of the molten material is
ununiform or decreases, the temperature of the molten material
around the molten surface may be uniformly controlled by stirring
the molten material. Although the method of controlling the
horizontal directional flow and the discharge flow of the molten
material by controlling the magnetic field direction, i.e., the
dynamic magnetic field direction, is described herein, the flow of
the molten material may be controlled by changing at least one of
the magnetic field direction and the magnetic field intensity as
necessary. Here, the magnetic field intensity may be changed by
adjusting the current amount of the alternating current supplied to
each of the dynamic magnetic field generators 310, 320, 330, and
340.
[0100] As the horizontal directional flow and the discharge flow of
the molten material in the mold is controlled by using the dynamic
magnetic field generation unit 300 based on the above-described
method, the molten surface of the molten material may be
stabilized, and the different kind of material such as the mold
slag or the mold flux disposed on the molten surface of the molten
material may be restricted or prevented from being mixed into the
molten material.
[0101] Although the exemplary embodiments of the present invention
have been described, it is understood that the present invention
should not be limited to these exemplary embodiments but various
changes and modifications can be made by one ordinary skilled in
the art within the spirit and scope of the present invention as
hereinafter claimed. Hence, the real protective scope of the
present invention shall be determined by the technical scope of the
accompanying claims.
INDUSTRIAL APPLICABILITY
[0102] In accordance with an exemplary embodiment, as the flow of
the molten material is selectively controlled in the longitudinal
direction of the mold by selectively applying the static magnetic
field in the width direction of the mold, the different kind of
material such as the mold flux or the mold slag may be restricted
from being mixed with the molten material to manufacture a high
quality product. Through this, as the cleanliness of the molten
material is secured, a product manufactured by using the molten
material may have an improved quality.
* * * * *