Note: Descriptions are shown in the official language in which they were submitted.
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Description
Twin-drum Continuous Casting Apparatus and Method
Technical Field
This invention relates to a twin-drum continuous
casting apparatus and method for continuously casting a
metal sheet.
Background Art
FIG. 17 is a perspective view of a general drum
continuous casting apparatus.
According to this apparatus, molten metal 3 is
supplied to a pouring basin formed by a pair of cooling drums
1, 1, rotating in opposite directions (directions of arrows
in the drawing), and side gates 2, 2, and is brought into
contact with the surfaces of the cooling drums 1, 1 to form
a solidified shell, casting a thin strip cast piece (metal
sheet) 4.
FIG. 18 is an enlarged sectional view taken on line
D-D of FIG. 17, showing a sliding portion of the side gate
in sliding contact with end portions of the cooling drums
at a kissing point at which the surfaces of the pair of
cooling drums become closest to each other.
End surfaces la, la of the pair of cooling drums
1, 1 move in sliding contact with a ceramic plate 5 mounted
on the side gate 2, and edge portions lb, lb of the surfaces
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of the pair of cooling drums 1, 1 seal up the molten metal
3, thereby preventing the molten metal 3 from leaking to
the outside of the pouring basin. At this time, the end
surfaces la, la of the pair of cooling drums 1, 1 have to
be free from relative displacement in the axial direction
(the drum axis direction) with respect to each other, and
have to contact the ceramic plate 5 on planes.
The conventional internal structures of the
above-described cooling drum 1 are shown in FIGS. 19 to 21.
Each of the cooling drums 1 has a structure in which
an outer drum sleeve 10 of a copper ( Cu ) alloy is supported,
from inside, by a drum body (core member) 11 of steel ( SUS )
in order to increase the rigidity of the cooling drum 1.
Hollow shaft portions ila are integrally assembled to
opposite end portions of the drum body 11. Arrows in FIGS.
19 to 21 indicate the flow of cooling water.
The cooling drum shown in FIG. 19 was proposed by
the present applicant in Japanese Patent Application No.
1986-66897. It is composed of the drum body 11, the drum
sleeve 10 detachably fitted on an outer peripheral portion
of the drum body 11, a pair of wedge rings 12A, 12B inserted
in joining end portions of the drum sleeve 10 and the drum
body 11 to fix the drum sleeve 10 and the drum body 11, and
hold-down rings 13 fastened to opposite end surfaces of the
drum body 11 to hold down one of the wedge rings, 12B.
FIG. 20 also shows a structure in which the drum
sleeve 10 is supported by the drum body 11 located inwardly,
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and bonding end portions of the drum sleeve 10 and the drum
body 11 are joined together by fillet welding 14.
FIG. 21 also shows a structure in which the drum
sleeve 10 is supported by the drum body 11 located inwardly,
and entire contact surfaces of the drum sleeve 10 and the
drum body 11 are joined together by shrink fit 15.
In the cooling drum shown in FIG. 19, however, the
axial elongation of the drum sleeve 10 due to thermal
deformation (heat load) during casting cannot be restrained
merely by the frictional force of the wedge rings 12A, 12B
to prevent slippage. As a result, the drum sleeve elongates
in the axial direction, and there is no guarantee that its
elongation is axially symmetrical with respect to the drum
center. Accordingly, a displacement in the axial direction
occurs between the end portions of the pair of cooling drums
1, 1, posing the problem that sealing of molten metal between
the cooling drums and the side gates 2 is insufficient.
In the cooling drum shown in FIG. 20, the sites of
the fillet welding 14 restraining the elongation of the drum
sleeve 10 are low in durability, and once either weld zone
is destroyed, the drum sleeve 10 does not elongate axially
symmetrically with respect to the center. Accordingly, a
displacement in the axial direction occurs between the end
portions of the pair of cooling drums 1, 1, posing the
problem that sealing of molten metal between the cooling
drums and the side gates 2 is insufficient.
In the cooling drum shown in FIG. 21, the entire
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surface of the joining portions of the drum sleeve 10 and
the drum body 11 can be clamped. However, even if clamping
can be performed most tightly within an elastic deformation
of the drum sleeve 10, the elongation force of the drum
sleeve 10 during casting is stronger than the frictional
force of the joining surfaces, so that slippage occurs at
the fitting surfaces. Moreover, there is no guarantee that
the drum sleeve 10 elongates axially symmetrically with
respect to the center. Accordingly, a displacement in the
axial direction occurs between the end portions of the pair
of cooling drums 1, 1, posing the problem that sealing of
molten metal between the cooling drums and the side gates
2 is insufficient.
Furthermore, a clamping force may be increased
during the shrink fit or the clamping to increase sliding
resistance, thereby preventing slippage at the fitting
surfaces. In this case, there is a risk that the drum sleeve
made of the copper alloy will be torn into pieces. To
prevent this risk, it was necessary to increase the
thickness of the drum sleeve 10 made of the copper alloy.
Thus, it was difficult to introduce forging during
the manufacturing process for the drum sleeve 10 made of
the copper alloy, and great variations arose in quality.
As a result, the surface layer of the drum sleeve 10 made
of the copper alloy was rapidly damaged under heat load
during casting, presenting the problem that the drum sleeve
10 made of the copper alloy had a short life.
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Conventionally, temperature control of the drum
body 11 was not performed, so that a drum crown (concave
crown) greatly changed under heat load during casting.
Thus, there was a problem that a cast piece having an
appropriate convex crown (cast piece crown) was not
producible.
The object of the present invention is to provide
a twin-drum continuous casting apparatus and method which
have means for preventing various adverse influences due
to differences in thermal expansion of constituent members,
thereby increasing the reliability of the apparatus, and
improving the quality of casting.
Disclosure of the Invention
To attain the above object, the invention claims
a twin-drum continuous casting apparatus for casting a
metal sheet by supplying molten metal to a pouring basin
formed by a pair of cooling drums rotating in opposite
directions, and side gates, to cool the molten metal by
contact with surfaces of the cooling drums, thereby forming
a solidified shell, wherein
the cooling drum is formed from a drum body having
shaft portions at opposite end portions, and a drum sleeve
fitted on an outer peripheral portion of the drum body, and
means is provided for preventing various adverse
influences due to differences in thermal expansion of
constituent members of the drum body during casting.
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According to this feature, various adverse
influences due to differences in thermal expansion of
constituent members are prevented, thereby increasing the
reliability of the apparatus, and improving the quality of
casting.
The drum body is formed from, and divided into, a
pair of shaft members having the shaft portions provided
integrally therewith and being joined to end portions of
the drum sleeve, and a core member located between the shaft
members and shrink fitted to an inner peripheral surface
of the drum sleeve without contacting the shaft members.
According to this feature, the end portions of the
pair of cooling drums can be prevented from axial
displacement, and leakage of molten metal can be prevented.
In shrink fit between the drum sleeve and the core
member supporting the drum sleeve from inside, a tightening
margin at an intermediate portion in a drum axis direction
is greater than a tightening margin at the end portion.
According to this feature, the intermediate portion
is higher in contact pressure resistance than the end
portion, and thus does not slip. On the other hand, the
opposite end portions slightly slide, with respect to the
intermediate portion of the drum sleeve and the core member,
during each rotation of the drum. A great movement of the
core member as a whole does not occur.
The wall thickness of the intermediate portion in
the drum axis direction of the core member supporting the
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drum sleeve from inside is larger than the wall thickness
of the end portion.
According to this feature, the intermediate portion
is higher in contact pressure resistance than the end
portion, and thus does not slip. On the other hand, the
opposite end portions slightly slide, with respect to the
intermediate portion of the drum sleeve and the core member,
during each rotation of the drum. A great movement of the
core member as a whole does not occur.
The end portions of the drum sleeve and the shaft
members are fastened together by bolts.
According to this feature, the tightening margin
of the fitting surfaces can be decreased. Thus, the
attachment and detacxunent of the shaft member are easy.
Many hot water channels, each extending in a drum
axis direction along joining surfaces of the drum body and
the drum sleeve, are formed at least within the drum body
at predetermined intervals in a circumferential direction.
According to this feature, a difference in thermal
expansion between the core member and the drum sleeve
reaching a high temperature during casting is decreased.
Thus, a shearing force acting on the shrink fit joining
surface between the drum sleeve and the core member becomes
lower than the frictional force, bringing about no
displacement. As a result, there is no axial displacement
between the end portions of the pair of cooling drums, and
molten metal leakage can be prevented.
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Supply and discharge of hot water into and from the
hot water channels are performed via hot water jackets
formed along an inner surface of the drum body in order to
heat the inner surface of the drum body.
According to this feature, hot water passes on the
inner surface of the drum body and through the interior of
the drum body. Thus, the entire drum body is heated.
Cooling water, which has flowed through a cooling
water hole of the drum sleeve and turned into hot water upon
heat exchange, is supplied to the hot water channels.
According to this feature, the supply of hot water
from the outside of the cooling drum is not required. Thus,
a hot water supply piping into the cooling drum, and so on
are unnecessary, and the structure is simplified, lowering
the cost for the cooling drum.
Hot water is supplied to the hot water channels
before start of casting to preheat the drum.
According to this feature, displacement between the
end portions of the pair of cooling drums during casting
is rendered inexistent, and the time required for a
preparatory operation for initiating casting is markedly
shortened.
The drum body is made of SUS, the drum sleeve is
made of a Cu alloy, and the SUS drum body is composed of
a plurality of ring-shaped core members arranged dividedly
at intervals in an axial direction.
According to this feature, inside the Cu alloy drum
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sleeve, the portions where the SUS core members fitted to
the drum sleeve and supporting it are present, and the
portions where the SUS core members do not exist are
alternately formed. The Cu alloy drum sleeve can freely
change in the axial direction in the portions where the SUS
core members are not present. In the portions where the
SUS core members are present, the axial length of the fitting
portion between the Cu alloy drum sleeve and the SUS core
members is divided into short lengths, so that relative
slide does not occur in the fitting portion. As a result,
a tightening force can be decreased in fitting the Cu alloy
drum sleeve and the SUS core members, and the Cu alloy drum
sleeve can be formed with a small thickness. Thus, the
cooling drum lightweight and having a long useful life is
obtained.
The Cu alloy drum sleeve is composed of a 60 to 100
mm thick sheet.
According to this feature, compared with the
conventional Cu alloy drum sleeve of this type, which has
a large wall thickness of 120 to 150 mm, the thickness can
be markedly decreased, and weight reduction and
prolongation of the useful life are achieved for the Cu alloy
drum sleeve.
Of the plural core members provided dividedly, the
core members located at opposite end portions of the drum
body have axial end surfaces to which drum shafts are fixed,
and have circumferential surfaces, which are fitted to the
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Cu alloy drum sleeve, formed so as to be wider than
circumferential surfaces of the core members at an
intermediate portion of the drum body, and the core members
arranged in the intermediate portion each have a convex
small-width portion on a circumferential surface thereof,
the convex small-width portion being fitted to the Cu alloy
drum sleeve.
According to this feature, the core members at the
opposite end portions can withstand a greater load. The
core members in the intermediate portion increase in the
proportion of the free zone relative to the elongation of
the Cu alloy drum sleeve, and the anti-slip effect at the
fitting surface is higher. Thus, a preferred cooling drum
with a long useful life is obtained which can find sufficient
use as a long-bodied, heavy-weight casting drum.
Outer layer water channels are provided in the drum
sleeve, inner layer water channels are provided in the drum
body, cooling water is supplied to the outer layer water
channels and the inner layer water channels, a measuring
device is provided for measuring a temperature of cooling
water discharged from the inner layer water channels, and
a control device is provided for controlling a temperature
of cooling water supplied to the inner layer water channels
in accordance with the cooling water temperature from the
measuring device.
According to this feature, the temperature of
cooling water supplied to the inner layer water channels
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is controlled in accordance with the temperature of cooling
water discharged from the inner layer water channels. Thus,
crown control of the metal sheet in response to thermal
expansion of the cooling drum can be performed with
satisfactory response.
Outer layer water channels are provided in the drum
sleeve, inner layer water channels are provided in the drum
body, cooling water is supplied to the outer layer water
channels and the inner layer water channels, a measuring
device is provided for measuring a profile in a plate width
direction of the metal sheet delivered from the cooling
drums, and a control device is provided for controlling a
temperature of cooling water supplied to the inner layer
water channels in accordance with the profile from the
measuring device.
According to this feature, the temperature of
cooling water supplied to the inner layer water channels
is controlled in accordance with the crown of the metal sheet
delivered fxom the cooling drums. Thus, crown control of
the metal sheet responsive to thermal expansion of the
cooling drum can be performed with high accuracy.
Outer layer water channels are provided in the drum
sleeve, inner layer water channels are provided in the drum
body, cooling water is supplied to the outer layer water
channels and the inner layer water channels, measuring
devices are provided for measuring a temperature of cooling
water discharged from the inner layer water channels, and
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a profile in a plate width direction of the metal sheet
delivered from the cooling drums, and a control device is
provided for controlling a temperature of cooling water
supplied to the inner layer water channels in accordance
with the cooling water temperature and the profile from the
measuring devices.
According to this feature, the temperature of
cooling water supplied to the inner layer water channels
is controlled in accordance with the crown of the metal sheet
delivered from the cooling drums and the temperature of
cooling water discharged from the inner layer water
channels. Thus, crown control of the metal sheet
responsive to thermal expansion of the cooling drum can be
performed with satisfactory response and high accuracy.
In a twin-drum continuous casting apparatus for
casting a metal sheet by supplying molten metal to a pouring
basin formed by a pair of cooling drums rotating in opposite
directions, and side gates, to cool the molten metal by
contact with surfaces of the cooling drums, thereby forming
a solidified shell, a twin-drum continuous casting method
comprising:
forming the cooling drum from a drum body having
shaft portions at opposite end portions, and a drum sleeve
fitted on an outer peripheral portion of the drum body, and
implementing means for preventing various adverse
influences due to differences in thermal expansion of
constituent members of the drum body during casting, said
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means being such that
many hot water channels, each extending in a drum
axis direction along joining surfaces of the drum body and
the drum sleeve, are formed at least within the drum body
at predetermined intervals in a circumferential direction,
and
supply and discharge of hot water into and from the
hot water channels are performed via hot water jackets
formed along an inner surface of the drum body in order to
heat the inner surface of the drum body.
According to this feature, a difference in thermal
expansion between the core member and the drum sleeve
reaching a high temperature during casting is decreased.
Thus, a shearing force acting on the shrink fit joining
surface between the drum sleeve and the core member becomes
lower than the frictional force, bringing about no
displacement. As a result, there is no axial displacement
between the end portions of the pair of cooling drums, and
molten metal leakage can be prevented. Furthermore, hot
water passes on the inner surface of the drum body and
through the interior of the drum body. Thus, the entire
drum body is heated.
A twin-drum continuous casting method comprising:
providing outer layer water channels in a portion
of each of cooling drums along a circumferential surface
of the cooling drum;
providing inner layer water channels inwardly of
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the outer layer water channels; and
casting a metal sheet while supplying cooling water
to the outer layer water channels and the inner layer water
channels, and further comprising:
measuring a temperature of cooling water discharged
from the inner layer water channels; and
controlling a temperature of cooling water supplied
to the inner layer water channels in accordance with the
measured temperature, thereby controlling crown of the
metal sheet.
According to this feature, the temperature of
cooling water supplied to the inner layer water channels
is controlled in accordance with the crown of the metal sheet
delivered from the cooling drums. Thus, crown control of
the metal sheet responsive to thermal expansion of the
cooling drum can be performed with high accuracy.
A twin-drum continuous casting method comprising:
providing outer layer water channels in a portion
of each of cooling drums along a circumferential surface
of the cooling drum;
providing inner layer water channels inwardly of
the outer layer water channels; and
casting a metal sheet while supplying cooling water
to the outer layer water channels and the inner layer water
channels, and further comprising:
measuring a profile in a plate width direction of
the metal sheet delivered from the cooling drums; and
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controlling a temperature of cooling water supplied
to the inner layer water channels in accordance with the
measured profile, thereby controlling crown of the metal
sheet.
According to this feature, the temperature of
cooling water supplied to the inner layer water channels
is controlled in accordance with the crown of the metal sheet
delivered from the cooling drums. Thus, crown control of
the metal sheet responsive to thermal expansion of the
cooling drum can be performed with high accuracy.
A twin-drum continuous casting method comprising:
providing outer layer water channels in a portion
of each of cooling drums along a circumferential surface
of the cooling drum;
providing inner layer water channels inwardly of
the outer layer water channels; and
casting a metal sheet while supplying cooling water
to the outer layer water channels and the inner layer water
channels, and further comprising:
measuring a temperature of cooling water discharged
from the inner layer water channels, and a profile in a plate
width direction of the metal sheet delivered from the
cooling drums; and
controlling a temperature of cooling water supplied
to the inner layer water channels in accordance with the
temperature of cooling water and the profile, thereby
controlling crown of the metal sheet.
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According to this feature, the temperature of
cooling water supplied to the inner layer water channels
is controlled in accordance with the crown of the metal sheet
delivered from the cooling drums and the temperature of
cooling water discharged from the inner layer water
channels. Thus, crown control of the metal sheet
responsive to thermal expansion of the cooling drum can be
performed with satisfactory response and high accuracy.
Brief Description of the Drawings
FIG. 1 is a sectional view of an internal structure
of a cooling drum showing a first embodiment of the present
invention.
FIG. 2 is an explanation drawing of a surface
pressure distribution at fitting surfaces of an end portion
of the cooling drum.
FIG. 3 is a sectional view of an internal structure
of a cooling drum showing a second embodiment of the present
invention.
. FIG. 4 is a sectional view of an end structure of
a cooling drum showing a third embodiment of the present
invention.
FIG. 5 is a sectional view of an end structure of
a cooling drum showing a fourth embodiment of the present
invention.
FIG. 6 is a sectional view of an end structure of
a cooling drum showing a fifth embodiment of the present
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invention.
FIG. 7 is a sectional view of an internal structure
of a cooling drum showing a sixth embodiment of the present
invention.
FIG. 8 is a sectional view taken on line A-A of FIG.
7.
FIG. 9 is a schematic configuration drawing of a
cold water line and a hot water line for the cooling drums.
FIG. 10 is a sectional view of an internal structure
of a cooling drum showing a seventh embodiment of the present
invention.
FIG. 11 is a sectional view taken on line B-B of
FIG. 10.
FIG. 12 is a sectional view of an internal structure
of a cooling drum showing an eighth embodiment of the present
invention.
FIGS. 13(a) and 13(b) show a cooling drum according
to a ninth embodiment of the present invention, FIG. 13(a)
being a longitudinal sectional view of the cooling drum,
and FIG. 13 (b) being an enlarged view of a portion C in FIG.
13(a).
FIG. 14 is a sectional view of an internal structure
of a cooling drum showing a tenth embodiment of the present
invention.
FIG. 15 is a vertical sectional view of the cooling
drum shown in FIG. 14.
FIG. 16 is a schematic configuration drawing of a
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crown adjusting device for the cooling drum.
FIG. 17 is a perspective view of a general drum
continuous casting apparatus.
FIG. 18 is an enlarged sectional view taken on line
D-D of FIG. 17, showing a sliding portion of a side gate
in sliding contact with end portions of the cooling drums
at a kissing point at which the surfaces of the pair of
cooling drums are closest to each other.
FIG. 19 is a sectional view of an internal structure
of a cooling drum as a conventional example.
FIG. 20 is a sectional view of an end structure of
a cooling drum as a different conventional example.
FIG. 21 is a sectional view of an end structure of
a cooling drum as a different conventional example.
Best Mode for Carrying Out the Invention
The twin-drum continuous casting apparatus
according to the present invention will now be described
in detail by embodiments with reference to the drawings.
[First Embodiment]
FIG. 1 is a sectional view of an internal structure
of a cooling drum showing a first embodiment of the present
invention. FIG. 2 is an explanation drawing of a surface
pressure distribution at fitting surfaces of an end portion
of the cooling drum.
As shown in FIG. 1, a cooling drum 1 includes a drum
body 11 having hollow shaft portions lla at opposite end
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portions, and a drum sleeve 10 fitted on an outer peripheral
portion of the drum body 11. The drum body 11 is formed
from, and divided into, a pair of shaf t members 11A having
the hollow shaft portions lla formed integrally therewith
and being joined to end portions of the drum sleeve 10, and
a core member 11B located between the shaft members 11A and
shrink fitted to an inner peripheral surface of the drum
sleeve 10 without contacting the shaft members 11A.
The drum sleeve 10 uses a material (e.g., a copper
alloy) provided with high strength by solution heat
treatment, followed by cold forging and aging treatment,
and is joined to the core member 11B by shrink fit 15. At
this time, tightening margin (by impartment of a crown) of
the shrink fit joining surfaces at the intermediate portion
in the axial direction of the drum is set at about 1.2 times
the tightening margin of the end portion.
Joining of the pair of shaft members 11A and the
drum sleeve 10 is performed by shrink fit , and the tightening
margin of the joining surface is somewhat smaller than that
in the shrink fit between the core member 11B and the drum
sleeve 10. A rigid material(e.g.,stainless steel) is used
for the shaft member 11A and the core member 11B.
Cooling water is flowed in through the hollow shaft
portion lla of one of the shaft members 11A, and discharged
through the hollow shaft portion lla of the other shaft
member 11A. In the interior of the cooling drum 1, cooling
water moves along two-route cooling water systems.
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In one of the routes, cooling water flowing in
through the hollow shaft portion lla of one of the shaft
members 11A is passed through a cooling water hole 17a inside
the one shaft member 11A, and guided into a cooling water
hole 18b within the drum sleeve 10. In the cooling water
hole 18b, cooling water takes away heat accumulated in the
drum sleeve 10. Then, the cooling water is passed through
a cooling water hole 17d within the other shaft member 11A
and a cooling water jacket 19b, and discharged to the outside
of the cooling drum through the hollow shaft portion lla
of the other shaft member 11A.
In the other route, cooling water is guided into
a cooling water hole 18a within the drum sleeve 10 through
a cooling water hole 17b inside the other shaft member 11A.
In the cooling water hole 18a, cooling water takes away heat
accumulated in the drum sleeve 10. Then, cooling water
passes through a cooling water hole 17c within the one shaft
member 11A and a cooling water jacket 19a, further passes
through a cooling water piping 20, and arrives at the cooling
water jacket 19b of the other shaft member 11A. From there,
cooling water is discharged to the outside of the cooling
drum through the hollow shaft portion lla of the other shaft
member 11A.
There are the two-route cooling water systems
arranged in the circumferential direction of the cooling
drum 1, with the two routes located alternately
circumferentially. Thus, cooling water flowing in the
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cooling water holes 18a, 18b within the drum sleeve 10 forms
counter flows.
According to the cooling drum 1 of the thus
constituted twin-drum continuous casting apparatus, the
drum sleeve 10 and the core member 11B are joined together
by the shrink fit 15. Thus, shear stress acting on the drum
sleeve 10 and the core member 11B during casting increases
because of a difference in thermal expansion, thereby
causing slippage of the joining surfaces. In the present
structure, however, the core member 11B and the pair of shaft
members 11A are separate members, and are out of contact
with each other. Moreover, the length of the fitting
surface of the shaft member 11A is short. Thus, a contact
pressure pattern, p, as shown in FIG. 2 appears during
casting. As a result, the inner fitting surface (the
surface facing the intermediate portion in the axial
direction of the drum) of the shaft member 11A slips, while
the outer fitting surface thereof does not slip.
Consequently, relative displacement in the axial direction
of the drum end surfaces with respect to bearings of the
pair of cooling drums 1 is inexistent.
Furthermore, the tightening margin of the joining
surfaces in the intermediate portion in the drum axis
direction of the drum sleeve 10 and the core member 11B is
set to be about 1.2 times the tightening margin of the end
portion. Hence, the intermediate portion is higher in
contact pressure resistance than the end portion, and thus
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does not slip. On the other hand, the opposite end portions
slightly slide, with respect to the intermediate portion
of the drum sleeve 10 and the core member 11B, during each
rotation of the drum. Hence, a great movement of the core
member 11B as a whole does not occur.
[Second Embodiment]
FIG. 3 is a sectional view of an internal structure
of a cooling drum showing a second embodiment of the present
invention.
This is an embodiment in which the wall thickness
of the intermediate portion in the drum axis direction of
the core member 11B, where a tightening margin for shrink
fit is to be increased, is made larger than the wall
thickness of the end portion to maintain a high contact
pressure resistance. This embodiment shows the same
effects as does the First Embodiment.
[Third Embodiment]
FIG. 4 is a sectional view of an end structure of
a cooling drum showing a third embodiment of the present
invention.
This is an embodiment in which the method for joining
of the drum sleeve 10 and the shaft member 11A is changed
from shrink fit to tightening by a bolt 21. According to
this embodiment, the tightening margin at the fitting
surfaces can be decreased. Thus, the advantage that the
attachment and detachment of the shaft member 11A are easy
is obtained, in addition to the same effects as in the First
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Embodiment.
[Fourth Embodiment]
FIG. 5 is a sectional view of an end structure of
a cooling drum showing a fourth embodiment of the present
invention.
This is an embodiment in which joining of the drum
sleeve 10 and the shaft member 11A is performed by welding
22= According to this embodiment, the advantage that a
joining operation is performed easily and promptly is
obtained, in addition to the same effects as in the First
Embodiment.
[Fifth Embodiment]
FIG. 6 is a sectional view of an end structure of
a cooling drum showing a fifth embodiment of the present
invention.
This is an embodiment in which the drum sleeve 10
is supported by a steel ring 23 bonded to the shaft member
11A by a bolt 21. According to this embodiment, the
advantage that there is the degree of freedom in the
selection of a material for the shaft member 11A is obtained,
in addition to the same effects as in the First Embodiment.
[Sixth Embodiment]
FIG. 7 is a sectional view of an internal structure
of a cooling drum showing a sixth embodiment of the present
invention. FIG. 8 is a sectional view taken on line A-
A of FIG. 7. FIG. 9 is a schematic configuration drawing
of a cold water line and a hot water line.
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As shown in FIGS. 7 and 8, the present embodiment
does not supply hot water from the outside of the cooling
drum during casting, but utilizes cooling water which has
become hot water after heat exchange. There are two routes
for cooling water guided into the cooling drum.
In one of the routes, cooling water of about 25
C, which has flowed in through a hollow shaft portion lla
of one of shaft members 11A, enters a cooling water jacket
20a. From there, cooling water is guided into a cooling
water hole 22b within a drum sleeve 10 through a cooling
water hole 21a formed in a core member 11B, the cooling water
hole 21a located beside the one shaft member 11A. In the
cooling water hole 22b, cooling water takes away heat
accumulated in the drum sleeve 10, warming to about 43
C. Then, cooling water passes through a hot water channel
30b extending within the core member 11B in the drum axis
direction along joining surfaces between the core member
11B and the drum sleeve 10, and arrives at a space inward
of the core member 11B past a cooling water hole 21b formed
in the core member 11B , the cooling water hole 21b located
beside the one shaft member 11A. From there, cooling water
is discharged to the outside of the cooling drum through
the hollow shaft portion lla of the other shaft member 11A.
In the other route, cooling water passes through
a cooling water piping 23 from the cooling water jacket 20a,
and enters another cooling water jacket 20b formed beside
the other shaft member 11A. From there, cooling water is
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guided into a cooling water hole 22a within the drum sleeve
through a cooling water hole 21c formed in the core member
11B, the cooling water hole 21c located beside the other
shaft member 11A. In the cooling water hole 22a, cooling
water takes away heat accumulated in the drum sleeve 10,
warming to about 43 C. Then, the warmed water passes
through a hot water channel 30a extending within the core
member 11B in the drum axis direction along joining surfaces
between the core member 11B and the drum sleeve 10, and
arrives at the space inward of the core member 11B past a
cooling water hole 21d formed in the core member 11B, the
cooling water hole 21d located beside the other shaft member
11A. From there, the warmed water is discharged to the
outside of the cooling drum through the hollow shaft portion
lla of the other shaft member 11A.
According to this route, the internal space of the
core member 11B is filled with cooling water of about 43
C which has finished heat exchange. The above two types
of routes for cooling water are arranged alternately in the
circumferential direction of the cooling drum 1. Thus,
cooling water flowing through the cooling water holes 22a,
22b within the drum sleeve 10, and cooling water after heat
exchange which flows through the hot water channels 30a,
30b within the core member 11B form counter flows (see FIG.
8). Other features are the same as in the conventional
example shown in FIG. 18.
According to the present embodiment, as described
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above, hot water for heating the core member 11B is cooling
water which has warmed up within the drum sleeve 10. Thus,
cooling water warming up in the drum sleeve 10 becomes about
43 C, and is capable of heating the core member 11B
sufficiently.
Because of this advantage, a difference in thermal
expansion between the core member 11B and the drum sleeve
reaching a high temperature during casting is decreased.
Thus, a shearing force acting on the shrink fit joining
surfaces between the drum sleeve 10 and the core member 11B
becomes lower than the frictional force, bringing about no
displacement. As a result, there is no relative
displacement at the end portions of the drum sleeves 10 of
the pair of cooling drums 1, and a poor seal between the
ends of the cooling drums and the side gate 2 can be
prevented.
Furthermore, the present embodiment does not
require the supply of hot water from the outside of the
cooling drum 1. Thus, a hot water supply piping into the
cooling drum 1, and so on are unnecessary, and the structure
is simplified, lowering the cost for the cooling drum 1.
In the present embodiment, as shown in FIG. 9, hot
water is supplied to and circulated through the
aforementioned two types of cooling water routes before
initiation of casting, thereby preheating the drum.
That is, a hot water line for supplying and
circulating hot water by switching (closing) shut-off
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valves 39a to 39d before start of casting is provided in
addition to a cold water line for supplying cooling water
to the above-mentioned two types of cooling water routes
during casting, the hot water line comprising a pit 31, a
pump 32, a steam supply source 33, a valve 34, check valves
35, 37, and a valve 38, and the cold water line comprising
a pit 24, a pump 25, and valves 26 and 27.
The temperature of the hot water is controlled by
detecting the temperature and pressure of hot water
downstream from the check valve 35, and controlling the
amount of steam feed from the steam supply source 33 by means
of a controller 36 (or an operator) on the basis of the
detected values of the temperature and pressure.
In the above-described manner, the drum is
preheated in order to decrease the difference in
temperature between the core member 11B and the drum sleeve
during casting as quickly as possible. By so doing, the
aforementioned displacement during casting is rendered
inexistent, and the time required for a preparatory
operation for initiating casting is markedly shortened.
[Seventh Embodiment]
FIG. 10 is a sectional view of an internal structure
of a cooling drum showing a seventh embodiment of the present
invention. FIG. 11 is a sectional view taken on line B-B
of FIG. 10.
This embodiment is an embodiment in which the
aforementioned two types of cooling water routes are the
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same as those in FIGS. 20 and 21 showing the earlier
technologies, but many hot water channels 40, each
extending in the drum axis direction along joining surfaces
of the core member 11B and the drum sleeve 10, are formed
within the core member 11B at predetermined intervals in
the circumferential direction.
The supply and discharge of hot water into and from
the hot water channel 40 are performed via a pair of hot
water jackets 41a, 41b arranged side by side on the inner
surface of the core member 11B, a supply piping 43a and a
return piping 43b piercing through a pair of hollow shaft
portions lla of the cooling drum 1, and a plurality of supply
pipes 42a and return pipes 42b disposed in the radial
direction of the drum so as to connect the hot water jackets
41a, 41b to the supply piping 43a and the return piping 43b.
Thus, hot water for heating the core member 11B is
guided into the cooling drum through the supply piping 43a
installed within the hollow shaft portion 11a of the other
shaft member 11A concentrically with the hollow shaft
portion lla. Hot water, guided to nearly the center of the
cooling drum 1 by the supply piping 43a, passes through the
plurality of supply pipes 42a extending radially of the drum.
Then, the hot water is guided to the hot water jacket 41a
installed on the inner surface of the core member 11B to
heat the inner surface of the core member 11B . The hot water
passes through the hot water holes 40 within the core member
11B to heat the joining surface of the core member 11B joined
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to the drum sleeve 10. Then, the hot water is guided to
the hot water jacket 41b to heat the inner surface of the
core member 11B, and is passed through the plurality of
return pipes 42b. Then, the hot water is guided into the
return piping 43b installed within the hollow shaft portion
lla of the one shaft member 11A concentrically with the
hollow shaft portion lla, and is discharged to the outside
of the cooling drum.
According to the so constituted cooling drum 1 of
the drum continuous casting machine, hot water of about 43
C passes on the inner surface of the core member 11B and
through the interior of the core member 11B. Thus, the
entire core member 11B is heated to decrease a difference
in thermal expansion between the core member 11B and the
drum sleeve 10 reaching a high temperature during casting.
Hence, a shearing force acting on the shrink fit joining
surfaces of the drum sleeve 10 and the core member 11B
becomes lower than the frictional force, thus bringing
about no displacement. As a result, there is no relative
displacement between the end portions of the drum sleeves
of the pair of cooling drums 1, and a poor seal between
the ends of the cooling drums and the side gate 2 can be
prevented.
In the present embodiment, like the Sixth
Embodiment, the drums are preheated. In this case, however,
hot water is not passed through the aforementioned two types
of cooling water routes, but is passed only through the hot
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water channels 40, unlike the Sixth Embodiment.
[Eighth Embodiment]
FIG. 12 is a sectional view of an internal structure
of a cooling drum showing an eighth embodiment of the present
invention.
In the present embodiment, the numeral 50 denotes
a cooling drum. The cooling drum 50 includes a drum sleeve
51 of a Cu alloy, and a plurality of ring-shaped cores 52
of SUS arranged dividedly at intervals in the axial
direction inwardly of the drum sleeve 51 of the Cu alloy
and fitted on the inner surface of the Cu alloy drum sleeve
51 by shrink fit. Of them, the SUS cores 53 located at
opposite end portions have axial end surfaces to which drum
shafts 54 are bonded by bolts 55.
The Cu alloy drum sleeve 51 fitted with the
ring-shaped SUS cores 52, 53 has a wall thickness of about
80 mm out of consideration for the fact that the temperature
of molten steel handled by the twin-drum continuous casting
apparatus is about 1,350 to 1, 450 C. This plate thickness
can be selected from the range of 60 to 100 mm.
The plurality of ring-shaped SUS cores 52 provided
dividedly can be selected in suitable numbers according to
the length of the drum body of the cooling drum 50 produced.
The axial length of the interval portion, at which the SUS
core 52 is not fitted to the Cu alloy drum sleeve 51, is
larger than the length of the width portion of each
ring-shaped core 52 fitted on the inner surface of the Cu
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alloy drum sleeve 51.
In the cooling drum 50 of the present embodiment
constituted in the above manner, when the Cu alloy drum
sleeve 51 elongates axially under heat load during a casting
operation, the interval between the adjacent ring-shaped
SUS cores 52 freely changes, so that slippage of the Cu alloy
drum sleeve 51 relative to each SUS core 52 is dissolved.
At the sites where the inner surface of the Cu alloy
drum sleeve 51 and the circumferential surfaces of the
ring-shaped SUS cores 52 are fitted together, the width
(axial length) of the fitting portion is so small that
relative slippage of the Cu alloy drum sleeve 51 within the
width of the fitting portion does not occur.
Thus, there is no need to apply a strong clamping
force to the fitting portion out of concern for relative
slippage between the Cu alloy drum sleeve 51 and the SUS
core 52 in the fitting portion. Nor is it necessary to
increase the thickness of the Cu alloy drum sleeve 51 for
fear of breakage by the clamping force. The Cu alloy drum
sleeve 51 can be thinned.
According to the findings obtained by the inventors
as a result of trial and error, the Cu alloy drum sleeve
51 effectively has a plate thickness of 60 to 100 mm, and
particularly preferably has a wall thickness of about 80
mm, in connection with the relationship of the thickness
to the temperature of molten steel and other operating
conditions, if the temperature of the molten steel handled
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by the twin-drum continuous casting apparatus relevant to
the present embodiment is 1350 to 1450 C.
As described above, the Cu alloy drum sleeve 51 in
the present embodiment, compared with a large plate
thickness of 120 to 150 mm, generally about 140 mm, in the
aforementioned conventional apparatus, has a plate
thickness which can be decreased to about a half of the above
value. Moreover, forging can be effected markedly during
the manufacturing process for the Cu alloy drum sleeve 51.
Thus, the Cu alloy drum sleeve 51 of stabilized quality is
obtained, and can achieve a longer service life than in the
earlier technologies.
Also, the Cu alloy drum sleeve 51 has a small plate
thickness, and thus the material cost of the Cu alloy is
low. Further, the operating time for the fitting step is
shortened, facilitating the fitting operation.
The present embodiment, therefore, gives the
effects that a high durability (long life), thin-walled,
lightweight cooling drum 50 free from slippage at the
fitting surface can be provided inexpensively, and the
productivity of the twin-drum continuous casting apparatus
can be increased.
[Ninth Embodiment]
FIGS. 13 (a) and 13 (b) show a cooling drum according
to a ninth embodiment of the present invention, FIG. 13(a)
being a longitudinal sectional side view of the cooling drum,
and FIG. 13(b) being an enlarged view of a portion C in FIG.
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13(a)
To avoid a verbose explanation, the sites of the
same constitution as in the aforementioned Eighth
Embodiment are indicated by the same numerals in the
drawings, duplicate explanations are omitted if possible,
and the points characteristic of the present embodiment are
emphatically described.
The present embodiment is preferred for use as a
cooling drum with a long body and a heavy weight. The
cooling drum includes a plurality of ring-shaped cores 52
of SUS arranged dividedly at intervals in the axial
direction. Of them, the SUS cores 53 located at opposite
end portions in order to have drum shafts 54 connected
thereto are slightly thicker in plate thickness than the
other SUS cores 52 arranged in the intermediate portion.
The SUS cores 53 are formed in a ring shape having a slightly
wide circumferential surface 53a fitted on the inner
surface of an end portion of a drum sleeve 51 of a Cu alloy.
The other ring-shaped SUS cores 52 arranged in the
intermediate portion have a convex small-width portion 58
on a circumferential surface 52a thereof. The convex
small-width portions 58 allow the ring-shaped cores to be
fitted to the Cu alloy drum sleeve 51 at spaced apart
positions in the axial direction.
In the cooling drum with the long body and heavy
weight, a heavier load is imposed on the ring-shaped SUS
cores 53 provided in a divided manner and arranged at the
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opposite end portions to which the drum shafts 54 are
connected.
In the present embodiment, therefore, the
circumferential surface 53a of each of the ring-shaped SUS
cores 53 provided in a divided manner at the opposite end
portions is made slightly thicker and wider than the
circumferential surface 52a of each of the other SUS cores
52 arranged in the intermediate portion. These
circumferential surfaces 53a are fitted to the Cu alloy drum
sleeve 51 to take charge of the necessary strength.
The SUS cores 52 arranged dividedly in the axial
direction in the intermediate portion have the convex
small-width portion 58 on the circumferential surface 52a,
and is fitted to the Cu alloy drum sleeve 51 at the body
convex small-width portion 58. Thus, there is an increase
in the proportion of the free zone relative to the elongation
of the Cu alloy drum sleeve 51, and the anti-slip effect
at the fitting surfaces is higher and more reliable, so that
the safety of the long-bodied cooling drum can be promoted.
(Tenth Embodiment]
FIG. 14 is a sectional view of an internal structure
of a cooling drum showing a tenth embodiment of the present
invention. FIG. 15 is a vertical sectional view of the
cooling drum shown in FIG. 14. FIG. 16 is a schematic
configuration druwing of a crown adjusting device for the
cooling drum.
As shown in FIG. 14, a cooling drum 104 has a
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structure in which a drum sleeve 105 of copper or copper
alloy located outwardly is supported from inside by a drum
body 106 of steel, such as stainless steel, to increase the
rigidity of the cooling drum 104. A circumferential
surface 104a of the drum is provided with a drum crown
(concave crown) which gives a desired cast piece crown
during casting. The drum body 106 is dividedly formed from
a pair of shaft members 108a, 108b having hollow shaft
portions 107a, 107b integrally molded therewith, and a core
member 110 located between these shaft members, coupled to
the shaft members by bolts 109, and mounted on the inner
peripheral surface of the drum sleeve 105 by shrink fit.
In the drum sleeve 105, many outer layer water channels 112a,
112b extending in the drum axis direction are provided at
predetermined intervals in the circumferential direction
of the cooling drum (see FIG. 15). Cooling water passing
through the outer layer water channels 112a, 112b moves
along the following two cooling water routes.
In one of the routes, cooling water flowing in from
one of the hollow shaft portions, 107a, is guided into the
outer layer water channel 112a provided in the drum sleeve
105 through a water passage llla formed in the core member
110 beside one of the shaft members 108a. In the outer layer
water channel 112a, cooling water takes away heat
accumulated in the drum sleeve 105. Then, cooling water
passes through a water passage 113a formed in the core member
110 beside the other shaft member 108b, and a cooling water
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jacket 114a, and is discharged to the outside of the cooling
drum through the hollow shaft portion 107b of the other shaft
member 108b.
In the other route, cooling water flowing in from
the one hollow shaft portion 107a is guided into the outer
layer water channel 112b provided in the drum sleeve 105
through a water passage lllb formed in the core member 110
beside the other shaft member 108b. In the outer layer
water channel 112b, cooling water takes away heat
accumulated in the drum sleeve 105. Then, cooling water
passes through a water passage 113b formed in the core member
110 beside the one shaft member 108a, and a cooling water
jacket 114b, and further arrives at the cooling water jacket
114a beside the other shaft member 108b past a cooling water
piping 115. From there, cooling water passes through the
hollow shaft portion 107b of the other shaft member 108b,
and is discharged to the outside of the cooling drum.
Inside the core member 110, many inner layer
water channels 116, extending in the drum axis
direction along the surface of joining between the core
member 110 and the drum sleeve 105, are provided at
predetermined intervals in the circumferential
direction of the cooling drum 1 (see FIG. 15). Cooling
water to pass through the inner layer water channels
116 is flowed through a supply pipe 119a from a supply
piping 118a, and guided into a cooling water jacket
117b to cool the inner surface of the core member 110.
Then, cooling water is guided to the inner surface
water channels 116, where
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it takes away heat accumulated in the core member 110. Then,
cooling water is guided to a cooling water jacket 117a to cool
the inner surface of the core member 110. Then, it is passed
through a return pipe 119b and a return piping 118b, and
discharged to the outside of the cooling drum.
As shown in FIG. 15, the outer layer water channels
112a, 112b and the inner layer water channels 116 are
provided side by side in a circle in the circumferential
direction of the cooling drum 104. The outer layer water
channels 112a and 112b are arranged alternately to form
flows of cooling water into counter flows, thereby
achieving a uniform temperature in the axial direction of
the cooling drum.
According to the thus constituted cooling drum, the
inner peripheral surface and outer peripheral surface of
the core member 110 are directly cooled with cooling water
passing through the inner layer water channels 116 and the
cooling water jackets 117a, 117b. Thus, the crown of the
cooling drum can be fully controlled. As a result, cast
pieces (metal sheets) having an appropriate crown can be
produced stably for a long period of time.
FIG. 16 is a view showing the outline of a device
for performing crown control of a cast piece with the use
of the cooling drum shown in FIGS. 14 and 15. In the drawing,
circulation paths 120a, 120b for cooling water passing
through the inner layer water channels 116 and the outer
layer water channels 112a, 112b shown in FIG. 14 are
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connected to the shaft members 108a, 108b of the cooling
drum 104. Water temperature adjusting devices 121a, 121b
using a cooler and an electric heater are connected to the
circulation paths 120a,.120b.
Water temperature gauges 122a, 122c are provided
on the entrance side of the water temperature adjusting
devices 121a, 121b, while water temperature gauges 122b,
122d are provided on the exit side of the water temperature
adjusting devices 121a, 121b. Temperature signals on the
temperature of cooling water measured with the water
temperature gauges 122a to 122d are taken into water
temperature control devices 124a, 124b. A thickness meter
123 for measuring the profile in the plate width direction
of a cast piece is provided below the cooling drum 104, and
thickness signals on the thickness of the cast piece
measured with the thickness meter 123 are taken into the
water temperature control device 124a.
Next, the method of controlling the crown of a cast
piece complying with claim 13 of the present application,
which uses the present apparatus, is described with
reference to FIGS. 14 to 16. Before start of casting, the
exit side water temperature of the inner layer water channel
116 and the temperature of the core member 110 are nearly
the same to achieve an equilibrium condition. When casting
is started, molten steel is deprived of heat by the
water-cooled drum sleeve 105 to form a shell. The heat that
has migrated from the molten steel to the drum sleeve 105
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CA 02587148 2007-05-11
is not transferred 100% to cooling water flowing through
the outer layer water channels 112a, 112b and discharged
to the outside of the drum, but remains in a certain
proportion in the drum sleeve 105 and further goes to the
core member 110. As a result, the temperature of the core
member 110 gradually rises with the progress of casting,
whereupon the exist-side water temperature of the inner
layer water channel 116 rises. If this state continues,
the entrance-side and exit-side water temperatures of the
inner layer water channel 116 rise. Consequently, the core
member 110 increases in temperature and thermally deforms,
changing the drum crown, leading to a change in the crown
of the cast piece.
To prevent the change in the cast piece crown, there
is need to keep the temperature of the core member 110 nearly
constant. Since the temperature of the core member 110 is
approximated by the exit-side water temperature of the
inner layer water channel 116, control is performed to keep
the exit-side water temperature constant. That is, the
water temperature control device 124a shown in FIG. 16 takes
in the amounts detected by the water temperature gauges 122a,
122b, and instructs the water temperature adjusting device
121a on the exit-side target water temperature of the inner
layer water channel 116 based on the detected values,
thereby controlling the exit-side water temperature of the
inner layer water channel 116 to become the target water
temperature.
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On the other hand, the drum sleeve 105 has the role
of forming a constant thickness of shell, and thus the
fluctuation of its temperature is not preferred. Also, the
drum sleeve 105 is made of a highlyheat conductive material,
and is close to the heat receiving surface. Thus, its
thermal expansion is completed in a short time after start
of casting, and changes thereafter are small. Hence,
cooling water supplied to the outer layer water channels
112a, 112b is preferably not temperature-controlled, but
is controlled in such a manner as to maintain a constant
temperature during casting.
That is, control of cooling water fed to the outer
layer water channels 112a, 112b is performed by comparing
the water temperatures, measured with the water temperature
gauges 122c, 122d, with the water temperature, for
obtaining a solidified shell of a predetermined thickness,
by the water temperature control device 124b, and
controlling the water temperature adjusting device 121b
based on signals corresponding to the differences found by
comparison and the water temperature difference between the
water temperature gauges 122c and 122d, thereby keeping the
temperature of the drum sleeve 105 constant during casting.
According to the control method recited in claim 13, the
response of the drum crown to control is excellent, because
the water temperature of the inner layer water channel,
greatly affecting the drum crown, is taken into the control
system. However, the cast piece crown, the object of
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control, is not taken into the control system, and thus the
control accuracy is one step short of satisfaction.
The control method for the cast piece crown
complying with claim 14 of the present invention is as
follows: The water temperature control device 124a shown
in FIG. 16 computes the cast piece crown from signals on
the profile in the plate width direction of the cast piece
measured with the thickness meter 123, and compares the
computed crown with the preset target crown. If the
computed crown is smaller than the target crown, the water
temperature control device 124a outputs a signal for
lowering the temperature of cooling water. If the computed
crown is larger than the target crown, the water temperature
control device 124a outputs a signal for raising the
temperature of cooling water. The water temperature
adjusting device 121a is controlled in accordance with such
signals.
Subsequently, the water temperature control device
124a accepts signals from the thickness meter 123, makes
comparisons with the target crown, and when the computed
crown reaches the target crown, stops control of the water
temperature adjusting device 121a. On the other hand,
control of cooling water fed to the outer layer water
channels 112a, 112b is the same as in claim 13. According
to the control method recited in claim 14, the cast piece
crown, the object of control, is taken into the control
system, so that the control accuracy is improved over the
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method of claim 13. However, the water temperature of the
inner layer water channel, which greatly affects the drum
crown, is not taken into the control system. Thus, a time
delay is liable to occur between the change in the water
temperature and the change in the cast piece crown, making
the response to control one step short of satisfaction.
In the foregoing descriptions, the cooling drum
comprising the drum sleeve of a steel alloy fitted around
the core member of stainless steel is taken as an example
of the cooling drum 104. However, the cooling drum 104 may
be one having the outer layer water channels along the
circumferential surface of the drum, and the inner layer
water channels inwardly of the outer layer water channels,
and the structure of and the raw material for the drum are
not restricted to those of FIG. 14.
[Experimental Examples]
The cast pieces produced by Examples of the present
invention and Comparative Examples were examined for the
proportion in which the crown resides in the range of the
target value t 5 Rm.
In the Comparative Examples, the cooling drums
shown in FIGS. 20 and 21 were used, and the temperature of
cooling water supplied to the cooling water channels
provided in the drum sleeve 10 was controlled in accordance
with the crown of the cast pieces delivered from the cooling
drums.
Example 1 of the present invention is an example
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following claim 13, in which the cooling drum 104 shown in
FIG. 14 was used, and the temperature of cooling water
supplied to the inner layer water channels 116 was
controlled in accordance with the temperature of cooling
water discharged from the inner layer water channels.
Example 2 of the present invention is an example
following claim 14, in which the cooling drum 104 shown in
FIG. 14 was used, and the temperature of cooling water
supplied to the inner layer water channels 116 was
controlled in accordance with the profile in the plate width
direction of the thin strip cast piece delivered from the
cooling drums.
Example 3 of the present invention is an example
following claim 15, in which the cooling drum 104 shown in
FIG. 14 was used, and the temperature of cooling water
supplied to the inner layer water channels 116 was
controlled in accordance with the temperature of cooling
water discharged from the inner layer water channels,
whereafter the temperature of cooling water supplied to the
inner layer water channels 116 was controlled in accordance
with the profile in the plate width direction of the thin
strip cast piece delivered from the cooling drums.
As a result, the proportion of the cast piece crown
being in the range of the target value 5 m was 50% in
the Comparative Examples, 87% in Example 1 of the present
invention, 95% in Example 2 of the present invention, and
100% in Example 3 of the present invention.
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Needless to say, the present invention is not
limited to the aforementioned Embodiments, and various
changes and modifications may be made without departing
from the gist of the present invention.
Industrial Applicability
As described above, the twin-drum continuous
casting apparatus and method according to the present
invention have means for preventing various adverse
influences due to differences in thermal expansion of
constituent members during casting using cooling drums,
thereby increasing the reliability of the apparatus, and
improving the quality of casting.
44
