Note: Descriptions are shown in the official language in which they were submitted.
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Field of the Invention
This invention relates to the casting of molten metal and, more
particularly, to oscillating molds for the continuous casting of ferrous metals,
such as steel, into shaped 6illets of indefinite length.
Descriptlon of the Prior Art
The contlnuous casting of ferrous metal involves pouring molten metal
into the upper end of an open, flow-through, water-cooled mold that has an open-
ing of a desired cross-sectional shape. The portion of metal which is in contact
with the cold mold surface solidifies and forms the outer surface or shell of the
billet~ The metal thus discharges from the lower end of the mold as a billet
which is at least partially solidified, has the cross-sectional contour of the
mold, and has an indefinite length. The shell of the billet has a tendency to
adhere and cling to the mold; but cyclically reciprocating or oscillating the
mold at a predetermined rate and through a predetermined amplitude overcomes
this adhesion tendency so that the shell will not rupture as it leaves the mold
and release the molten metal that exists in the central core of the billet.
Haussner et al.'s U.S. Patent No. 3,040,397 discloses an arrangement
for reciprocating the mold mechanism at a desired rate and amplitude. Hydrau-
lic rams move the mold downwardly from a starting position and compression
springs move the mold upwardly to return it to the starting position. The
hydraulic rams are mounted below the mold supporting table and the springs are
mounted between the supporting table and the mold. The system has generally
worked well in practice. However, the structure of the oscillating mechanism
and its location with respect to the mold table has made maintenance and repair
of the oscillating mechanism difficult. The system also is cumbersome and has
required a considerable amount of space. Other systems that extend over two
operating levels and are even more cumbersome and difficult to maintain are fully
disclosed n U,S, Patent No. 3,2S8,815 to Reinfeld et al. and U.S. Patent No.
3,638,714 to ~ewhall et al " both assigned along with the Haussuer et al. patent
to the assignee of the present invention.
Brief Summary of the Invention
The present invention represents an improvement over the systems of
U,S. Patents Nos. 3,040,397, 3,258,815 and 3,638,714 in that it overcomes the
6pace and maintenance problems of such oscillating mechanism designs as those
described in the cited patents. In a preferred embodiment, this invention
provides a single unitary mold and oscillating unit in which the mold or the
oscillating unit or both can be quickly and readily installed on the operating
floor, and Just as quickly and readily removed in the event of operating diffi-
culties, In such a preferred unit, a common base is provided for a single com-
pression ~pring and the cylinder of a single hydraulic ram or, more particularly,
both the ram piston and the compression spring employed are within a common
cylinder. The mold rests within the ram piston so that it can readily be removed
from the piston for replacement or repair.
The foregoing and other objects, features and advantages of this
invention will become more apparent when taken in con~unction with the following
6peciflcation, the accompanying drawings and the appended claims.
Brief Description of the Drawings
Figure 1 is a generally schematic elevation of a continuous casting
machine and the preferred oscillating mold constructed in accordance with this
invention.
Figure 2 is an enlarged cross-section, in elevation, showing details
of the preferred oscillating mold of Figure 1.
Figure 3 is a sectional view of a portion of an alternative p~ston-
cylinder arrangement designed for utilizing hydraulic fluid in the lower chamber
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and a spring in the upper chamber of a mold oscillating assembly of this
invention~
Description of the`Preferred Em~odi~ent
Shown in Figure 1 and as described in the Haussner U.S. Patent No.
3,040,397, molten metal for the continuous casting operation flows from a tiltable
ladle (not shown) into a tundish 10 and then into the upper open end of a vertical
tubular mold 12 which has an outer ~ac~et 14 through which cooling water is cir-
culated, A mold reciprocating mechanism lowers and advances the mold 12 from a
starting position in the direction of travel of the billet 16 and raises or
retracts the mold 12 to its starting position. The advance or downward movement
of the mold mugt be at substantially the same speed as the casting rate in order
that no relative movement occurs between the constantly downwardly moving billet
16 and the mold 12 that could cau~e rupture of the billet's outer shell.
Not disclosed in the Haussner patent but, as shown in Figure 1, addi-
tional cooling of the billet may be provided by a spray box 18. Spray box 18
is simply an open-ended chamber or compartment, which may be generally rectangular
in shape, through which the billet 16 passes after it leaves mold 12 and which is
provided with spray heads 20 for spraying cooling water on the billet 16. Two
spray heads 20 are shown for the sake of clarity, although generally at least
four spray heads arranged at 90 to each other ere employed. As will be apparent,
cooling water is fed to the spray heads 20 through a spray conduit 22, which in
the unique arrangement of Figure 1, is connected by a swivel pipe ~oint 24 to a
supply conduit 26 connected to a source of cooling water (not shown).
Spray box 18 is supported in its operative position by a releasable
bracket 28. When necessary to ser~ice or replace the spray box 18 or, for any
reason to obtain access to the bottom of mold 12, during a cessation of the
casting operation, it will be apparent that releasing bracket 28 will permit
swiveling spray box 18 and spray conduit 22 to the desirable seryice position
shown in phantom In any event, during normal operation, spray box 18 assists
mold outer ~acket 14 In solidifying the molten metal into an at least partially
solidified billet capable of withstanding handling. Generally, pinch rolls
(not shown) frictionally engage the periphery of the solidified or partially
solldifled billet at some point after it emerges from the lower end of the mold
12 and controls the rate at which the billet ls withdrawn.
Haussner et al,'s U S. Patent No. 3,040,397 discloses the reciproca-
tion or oscillation of the mold by a hydraulic system for advancing the mold andspring means for retracting the mold and its control for selectively advancing
said mold at the same speed as said withdrawal rate by controlling the flow of
hydraulic fluid to and from the rams, for automatically reversing ~low of the
hydraulic fluid at the limits of movement of the mold, and for controlling the
acceleration of the mold advance movement.
The continuous casting system of Haussner et al. has generally worked
well in practice but the separate arrangement of the hydraulic advancing rams and
the retracting springs by which the mold is oscillated has created problems.
In accordance with the preferred embodiment of this invention there
is provided a novel compact integral unit for a continuous casting machine.
Referring now to Figure 2, the continuous metal casting apparatus of
thls inventlon involves a conventional water-cooled flow-through mold 12 having
an upper end 30 for receiving metal in a molten stage and a lower end 32 for
discharging the metal as a billet 16 that it at least partially solidified.
Two concentric and coaxial tubular members, inner tubular member 34 and outer
tubular member 36, are in a relatively axially-movable relationship and have
different diameters so as to provide an annular space 38 between them. Mold 12
is secured to and nestled in the inner tubular member 34 so that the billet 16
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travels in a generally axial direction with respect to the tubular members 34
and 36 and the mold 12. A closure 4Q closes the annular space 38 at the upper
end 42 of outer tubular member 36 but permits a sliding and engaging relationship
with the inner tu6ular member 34. An annular member 44 that is fixed to said
inner tubular member 34 and is slidably engaged with the outer tubular member 36
closes and divides the space 38 into spaces 46 and 48. The space 46 between the
members 34 and 36 is gealed for the application of a pressurized hydraulic fluid.
The flowing hydraulic fluid under pressure from inlet 50 into the space 46 causes
a relative movement of the tubular members in one direction and a spring 52 in
8pace 46 that engages with tubular member 34 and is stressed by such movement
will, upon release of the hydraulic pressure through outlet 54, return the
tubular member 34 to its original position. Mold 12 is thus oscillated to over-
come any tendency for the metal that is being cast to adhere to the mold.
Bottom end ring 56 is secured to outer member 36 by suitable means
such as welding 58. Ring 56 extends within and without member 36. The outside
portion has apertures 60 so that it can be secured to the operating floor 62 as
by bolts 64, The inside portion of ring 56 sets as a base for the circular com-
pression ring 52 which engages member 44, also. A cap ring 40 rests on member
36 and slidably engages member 34. A ring 66 is held to member 36 by suitable
means such as weld 68 and abutment 70. Cap ring 40 and ring 66 are secured
together by bolts 72.
The annular space 38 between members 34 and 36 constitutes the space
46 for hydraulic fluid which, through a port 50, flows into space 46, and acting
upon the annular member 44 renders member 44 effective as a ram or p~ston and
forces it downwardly, thereby compressing spring 52. As shown, the member 44
has mo~ed to its furthest position downwardly. Upon release of the pressure
fluid through outlet port 54, the compressed spring 52 moves member 44 upwardly.
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Thus, the inner member 34 is advanced from an initial position in the direction
of the travel of the billet 16 upon the influence of the pressure of the
hydraulic fluid and is then retracted by the action of spring 52 to the initial
position upon the release of this pressure. The control of the flow of hydraulic
fluid into and out from space 46 may, if desired, be through a single port as
shown in Figure 2 of U.S. Patent No. 3,040,397. Suitable sealing means such as
piston rings 74 prevent the loss of hydraulic fluid from the hydraulic space 46.
Tubular member 34 terminates at its upper end with an annular ring 76
that is attached to it by suitable means such as bolts 78. Resting on ring 76
and within inner tubular member 34 is a conventional continuous casting water-
cooled mold 12, ~t spaced locations on ring 76 are a series of fixed pins 80
that mate with cylindrical leveling screws 82 that are threaded into a plate 84
that is secured to mold 12 by conventional means such as welds 86. These level-
ing screws enable the mold to be leveled or made plumb. Wedges 88 received in a
slot in the upper portion of pins 80 lock the leveling screws 82 with respect to
pins 80 and secures plate 84 with respect to plate 76. Simple extraction of
these wedges makes ready removal and replacement of molds possible. Thus, a~
plate 76 oscillates upwardly and downwardly with inner tubular member 34, the
mold 12 moves with it. This oscillation or reciprocation is at a rate and
through a displacement length to prevent the adhesion of the metal to the mold.
Mold 12 may be conventional and have, for example, a metal molding
cross section of square shape. Such molds generally have a copper body which
$s encloset within a ~acket 14 to which water is supplied and withdrawn by way
of pipes suitably provided with allowance for oscillation of the mold. Such is
conventional construction.
The foregoing has described a novel unitary continuous casting unit
with a mold and osc~llating apparatus therefor. The unit will be situated on
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the operating floor (without any additional structure on the lower floors).
Thus the floor below the oscillating unit, where sprays are normally used to
further cool the billet after it leaves the mold, is free of mold oscillating
apparatus The entire unit is assembled as a complete design so that if there
be any breakdown, the entire unit can be disconnected and replaced in a short
time, The unit, belng compact, has an advantage in that it is light in weight
as compared to the heretofore known units and, thus, leads directly to cost
savings in the manufacture of the casting unit, as well as a reduction in the
over-all size of the steel structural support required therefor. Particularly
noteworthy is the large effective area of piston provided by the disclosed pre-
ferred embodiment, thus permitting lower hydraulic pressures, e.g., approximately
50 psi, to be employed for greater ease in operational control. Also noteworthy
is the unique spray box arrangement disclosed which, as aforesaid, enhances its
repair or replacement as well as access to the bottom of the casting mold, if
required.
While the foregoing has described a certain preferred embodlment of
the invention, it will be understood it may otherwise be embodied within the
scope of the following claims. For example, it is considered to be within the
skill of the art to appropriately provide for spring biasing in an upper chamber,
as illustrated in portion in Figure 3 and hydraulic biasing in a lower chamber
or even hydraulic biasing in both an upper and a lower chamber. Also, while the
preferred embodiment is considered to be the optimal arrangement, it could be
approached by providing a plurality of internally 6pring loaded piston-cylinder
assemblies, commonly mounted and circumscribing the mold and mold cooling ~acket,
with piston rods operatively connected in any desired manner, such as to annular
ring 76, to reciprocate the mold.
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