Pouring device for dual-roll type continuous casting machines

Melt flows down through downspouts into a basin defined by a pair of cooling rolls and side dams. Melt is decreased in flow rate to be supplied uniformly through a slit nozzle in a widthwise direction of the cooling rolls so that a solidified shell formed over the cooling rolls can be prevented from being melted again.

BACKGROUND OF THE INVENTION 
The present invention relates to a pouring device for a dual-roll type 
continuous casting machine for direct formation of melt into a strip of 
sheet metal. 
Well known in the art are continuous casting machines in which melt such as 
molten steel is poured into a water-cooled mold to form a casting which is 
pressed by a plurality of rollers and drawn into slabs, billets or the 
like. The slabs or billets thus cast are cut into a predetermined length 
and then transferred through a heating furnace to a rolling mill. As an 
improvement in the structure of such continuous casting machines for 
producing slabs, billets or the like, a so-called dual-roll type 
continuous casting machine capable of forming melt directly into a strip 
of sheet metal has been devised and demonstrated. 
As shown in FIGS. 1 and 2, a dual-roll type continuous casting machine 
comprises a pair of cooling rolls 1 disposed horizontally and 
substantially in parallel with each other in a spaced-apart relationship. 
Side dams 2 are disposed at widthwise ends of the rolls 1. A tundish 4 for 
pouring melt 3 is disposed above the cooling rolls 1 and a core 5 extends 
downwardly from the bottom of the tundish 4. A pouring passage 6 for 
pouring melt 3 is defined through the tundish 4 and the core 5. The pair 
of cooling rolls 1 and the side dams 2 at the widthwise ends thereof 
define a basin 7 into which the bottom of the core 5 is immersed. The 
pouring passage 6 is positioned to open substantially toward a middle 
point between the axes of the rolls 1. Melt 3 is charged from the tundish 
4 through the pouring passage 6 to form a basin 7 where melt 3 is cooled 
by the pair of cooling rolls 1 to form a solidified shell 8, whereby a 
casting 9 in the form of sheet metal is continuously cast by rotation of 
the cooling rolls 1 in the directions indicated by the arrows. 
When melt 3 is poured from the tundish 4 through the core 5 into the basin 
7 in the dual-roll type continuous casting machine described above with 
reference to FIG. 1, the pressure or flow rate of melt 3 is so high that 
contact of melt 3 with the solidified shell 8 which is being formed by the 
cooling rolls 1 tends to result in re-melting of the solidified shell 8. 
Such re-melting of the solidified shell 8 will cause variations in 
thickness, cracking or bulging of the casting 9. It follows therefore that 
in order to prevent the re-melting of the solidified shell 8, the pressure 
or flow rate of melt flowing down out of the pouring hole 6 of the core 5 
must be decreased and a countermeasure for avoiding direct contact of melt 
3 being poured with the solidified shell 8 must be devised. 
In view of the above, a primary object of the present invention is to 
provide a pouring device for a dual-roll type continuous casting machine 
in which a manifold for temporarily receiving melt from the tundish is 
disposed within the core so that the pressure or flow rate of melt flowing 
down out of the core is decreased and direct contact of melt with the 
solidified shell is avoided. 
The above and other objects, features and advantages of the present 
invention will become more apparent from the following description of 
preferred embodiments thereof taken in conjunction with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The same references numerals are used to designate similar parts throughout 
FIGS. 1, 2, 3 and 4. 
Referring now to FIGS. 3 and 4, a first embodiment of the present invention 
will be described. A pair of cooling rolls 1 are disposed horizontally and 
substantially in parallel with each other and are spaced apart from each 
other in the radial direction thereof. Side dams 2 are disposed at the 
widthwise ends of the cooling rolls 1 so that the pair of cooling rolls 1 
and the side dams 2 at the widthwise ends thereof define a basin 7. A 
tundish 4 for pouring melt 3 is disposed above the cooling rolls 1 and a 
core 10 extends downwardly from the bottom of the tundish 4 such that the 
lower end of the core 10 is submerged into the basin 7 and both sides of 
the core 10 extending in the widthwise direction of the cooling rolls 1 
are made into contact with the side dams 2. In the core 10, intermediate 
and side pouring passages 12 and 13 in communication with respective melt 
charging holes or downspouts 11 of the tundish 4 are defined in the 
widthwise direction of the cooling rolls 1. The pouring passages 12 and 13 
substantially vertically extend downwardly along a plane in the middle 
between the axes of the rolls 1, i.e., the plane passing the midpoint of a 
line interconnecting the axes of the rolls 1 at right angles to the line. 
A manifold 14 is defined within the core 10 and is communicated with the 
lower end of the intermediate pouring passage 12 and further with 
discharge passages 15 of the core 10. The discharge passages 15 in the 
form of slits extend in the widthwise direction of the cooling rolls 1 and 
slit nozzles 17 are opened toward a point 16 (higher than a position where 
the solidified shell 8 is started to be formed) at which the cooling rolls 
and melt contact with each other under the condition that the core 10 is 
kept submerged into the basin 7. No manifold is provided for the side 
pouring passages 13 since melt must flow there under higher pressure or at 
higher flow rate so as to melt the solidified shell 8 especially grown at 
the side dams 2 for prevention of the solidified shell 8 from growing at 
the triple points defined by the cooling rolls 1, the side dams 2 and melt 
3 and for prevention of resulting damages along the widthwise sides of the 
casing 9 during rotation of the cooling rolls 1. 
Next the mode of operation will be described. When melt 3 in the tundish 4 
is charged through the downspouts 11, it flows through the intermediate 
pouring passage 12, the manifold 14 and the discharge passages 15 as well 
as through the side pouring passages 13 so that the basin 7 is defined by 
the cooling rolls 1 and the side dams 2 disposed at the widthwise ends 
thereof. Melt 3 flowing down through the intermediate pouring passage 12 
is temporarily stored in the manifold 14 in communication with the lower 
end of the intermediate pouring passage 12. While the melt 3 is decreased 
in flow rate it melt 3 flows through the slit nozzles 17 toward the point 
16 of contact between the cooling rolls 1 and melt 3. It follows therefore 
that melt at higher pressure or flow rate is prevented from directly 
acting on the solidified shell 8 formed by the cooling rolls 1 below the 
core 10. Furthermore, the direction of flow of melt is toward the point 16 
of contact of the cooling roll 1 with melt 3 so that the solidified shell 
8 can be prevented from being melted again. As a result, even during 
supply of melt 3 to the basin 7, the basin 7 can be maintained in the 
stable state and a high-quality casting 9 uniform in thickness and free 
from cracks and bulging can be continuously formed. 
Referring next to FIGS. 5 and 6, a second embodiment of the present 
invention will be described. A pair of cooling rolls 1 are disposed in 
parallel with each other in a spaced-apart relationship and side dams 2 
are made into contact with both end faces of the cooling rolls 1, whereby 
a basin 7 for receiving melt 3 therein from a tundish 4 is defined. A core 
which is supportedly inserted into the basin 7 is vertically divided into 
two sections 19 and 21 along a plane in the middle between the axes of the 
cooling rolls. Opposing surfaces of the core sections 19 and 21 define a 
slit nozzle 18. One 19 of the two core sections is held stationary as a 
stationary core and is formed with a manifold 20 with a widthwise 
extending step for decreasing the flow rate of melt 3 flowing down through 
a downspout 11 extending downwardly from the tundish 4 to charge melt 3 
into the basin 7. The manifold 20 is communicated with the slit nozzle 18 
and has a widthwise distance larger than that of the latter; that is, the 
distance between the inner wall above the step of the stationary core 
section 19 and the opposing inner wall surface of the other core section 
21 is selected longer than the distance between the inner opposing 
surfaces of the core sections 19 and 21 below the step of the core section 
19 which together define the slit nozzle 18. 
The other core section 21 is so supported as to move toward or away from 
the stationary core section 19 so as to adjust the distance between the 
core sections 19 and 21. The movable core section 21 is connected to and 
is driven by an actuator 22 disposed outwardly of the core section 21. 
Melt 3 flowing down through the downspout 11 from the tundish 4 is 
temporarily received in the manifold 20 which is defined by the step on 
the stationary core section 19 so that the flow rate of melt 3 is 
decreased and the impact of melt is reduced. Thereafter melt 3 flows from 
the manifold 20 into the slit nozzle 18. The actuator 22 is adapted to be 
energized to move the movable core section 21 toward or away from the 
stationary core section 19, thereby adjusting the width of the slit nozzle 
18 and consequently controlling the flow rate of melt 3 flowing through 
the nozzle 18. 
According to the second embodiment with the abovedescribed construction, 
the flow rate of melt flowing downwardly is decreased in the manifold and 
melt 3 is poured uniformly in the widthwise direction through the slit 
nozzle 18. As a result, any local delay in growth of the solidified shell 
8 formed around the outer cylindrical surfaces of the cooling rolls 1 and 
melting of the existing solidified shell 8 can be prevented. 
Furthermore, depending upon casting conditions, the actuator 22 is 
energized to adjust the width of the slit nozzle 18 in the manner 
described above to thereby control the quantity of melt to be poured. 
FIG. 7 shows a first modification of the core portions described above with 
reference to FIG. 6. The movable core section 21 is further sectioned 
along the width of the rolls 1 into three sub-sections which are connected 
to and driven by three independent actuators 22 independently of each 
other. 
According to the first modification, the width of the slit nozzle 18 may be 
varied along the width of the rolls 1 to adjust the flow rates of melt 
especially at widthwise ends (that is, zones adjacent to the side dams), 
whereby the triple-point problem can be solved. The movable core section 
21 has been described as being further sectioned into three sub-sections, 
but is is apparent that the movable core section 21 may be sectioned into 
four or more sub-sections. It has been described that the manifold 20 is 
formed in one of the two core sections 19 and 21; but as shown in FIG. 8, 
both of the core sections 19 and 21 may be stepped to form a manifold 20 
for each of the core sections 19 and 21. Furthermore, a recess or recesses 
for storing melt therein may be formed on the step. Furthermore, other 
modifications may be of course effected within the true spirit and scope 
of the present invention. 
As described above, with the pouring device for a dualroll type continuous 
casting machine in accordance with the present invention, the flow rate of 
melt charged into the basin can be decreased and then melt is supplied in 
the form of a slit. Therefore, melt can be poured out slowly and uniformly 
in the widthwise direction so that the poured melt will not adversely 
affect the existing solidified shell. As a result, a high-quality casting 
in the form of sheet can be formed in a stabilized manner; the yield can 
be increased; and serious troubles can be avoided so that a high degree of 
productivity of a dual-roll type contious casting machine can be ensured.