Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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"IMPROVEMENTS IN M~TAL POURING APPARATUS"
This invention relates to improvements in metal
pouring apparatu~, and more particularly to improve-
ments applicable to the control of pouring or teeming
of molten metal along a duct or spout rrom one vessel
to another.
More explicitly, the invention concerns a teeming
control apparatus by means of which certain operational
problems can be reduced or eliminated both at the
commencement, and in the course, of teeming.
Metals may be poured from one vessel to another
in several ways. One way, to which the present in-
vention is not directed, involves tilting the charging
vessel to pour the molten metal or melt over a top
lip and thus into the receiving vessel. The invention,
instead, is concerned with the through-wall teeming,
especially the bottom pour teeming technique.
In through-wall and bottom-pour teeming, the
melt exits the charging vessel via a pour opening
in the wall or bottom, and then traver~eA a duct,
spout or nozzle for discharge into the receiving
vessel. Teeming is initiated and controlled by a valve
arrangement. Two kinds of valve arrangement are well
known: they are the stopper rod and the gate valve
systems.
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In principle the ~topp~r rod system ls slmple
and effective. It can reliably initiate a teem and
- to a degree - can control the teering rate, espec-
ially when the stopper rod and pouring opening are
in good condition. However, they are subject to the
effects of wear, attack and erosion by the molten
metal and in part through these efrects proper and
accurate control of the teeming rate can be difficult
to accomplish. Accurate control is important especially
in continuous casting operations.
The gate valve system is better able to control
the teeming rate and, in an emergency, may enable
teeming to be shut off more quickly. Nevertheless,
practical problems can arise. Unlike the stopper rod
system, the gate valve system is operative at the
bottom or outer end of the pour opening, rather than
at its top or inner end. In the absence of 3teps to
prevent it, molten metal enters and fills the opening
before a teem is initiated. The static metal may well
freeze or become pasty there in the pour opening.
This can prevent clean "opening" or commencement of
a teem. To combat this problem, a refractory partic-
ulate filler may be charged into the pour opening
before the charging vessel is filled ~ith molten metal.
25 The filler i9 supposed to discharge ahead of the metal
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when the valve is first opened to commence a teem.
ThiQ unfortunately doe~ not always happen. The filler
may sinter or develop a hard crust blocking the pour
opening. Again, therefore, clean opening may not be
attained. Of course, the filler is only useable when
teeming is first initiated. If teeming is interrupted
for any reason, static metal could freeze in the pour
opening before teeming is re-commenced.
Another problem with the gate valve system is
the ingress of air into the stream of teeming metal.
This is particularly likely to happen when practising
submerged-pour teeming. In this technique, the duct,
spout or nozzle has its discharge end immersed in
the melt in the receiving vessel. An object of sub-
merged pouring is to prevent contamination of themelt by air and this object is obviously defeated
if air is drawn into the teeming system by the flowing
melt. Not uncommonly, air is sucked in via the juncture
between relatively movable valve plates of the gate
20 valve. A solution exists : the valve is surrounded
by an atmosphere of inert gas. This is expensive to
maintain. Moreover, inert gas instead of air can enter
the teeming system and, whilst it might not affect
the constitution of the metal, it could still produce
25 metal castings having porosity defects.
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The present invention inter alia aims to overcome
the foregoing problems. Thus, it aims to provide
teeming apparatus capable of controlling onset, rate
and termination of a teem, simply and effectively,
to facilitate clean opening of a teem, and to minimiqe
or eliminate the possibility of insufflation of air
or other gas into the melt stream.
Desirably, the invention is embodied in such
a form as will enable it to be installed in a variety
of charging vessels. Such vessels can include ladles,
degassing vessels and tundishes. Also, desirably,
the invention is applicable with a variety of such
vessels and other vessels includin2 moulds, partic-
ularly continuous casting moulds.
If employed for teeming molten metal into con-
tinuous casting moulds, the invention is desirably
capable of efficiently distributing the melt into
bloom and slab moulds.
According to the present i mention, there is
provided metal teeming apparatus comprising a duct
or spout having entry and outlet ends respectively
formed with a valvs seat and with at least one exit
opening, and a valve member in the duct and reciproc-
ally movable lengthwise thereof, the valve member
having an enlargement at one end to coact with the
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valve seat for blocking or openin~ the duct entry
end when the valve member is moved to and Pro, and
a configuration at its other end for controlling flow
through the exit opening when the enlargement i~ dis-
engaged from the seat.
To avoid the risk of air ingress, the duct orspout is an elongate, unitary member devoid of any
~oints between its end~.
Except for the teeming of lo~er melting point
metals, the duct or spout and the ~alve member will
usually both be made of, or coated with, refractory
material resistant to wear and attack by molten metal.
The materials will be selected according to the metal
to be teemed and its temperature, as vill be under~tood
by the addressee. For teeming ferrou~ melts aluminous
material is suitable, for instance in pressed and
fired state.
In one embodiment of the invention, t h e d u c t
ha~ a convergently tapered outlet end leading to the
exit opening and the valve member ha~ a tapered con-
figuration at its said other end for coactin~ with
the tapered outlet end to control flow. Preferably, the
.~ coacting valve member and outlet end provide for pass-
age of melt from the duct when the ~alve member has
lts enlargecent enBaBed ~ith the val~e seat, ~n use
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for draining melt from the duct, t h e valve member
and outlet end can define an annulan drainage clear-
ance. In other words, the arrangesent can be such
that the exit opening is not completely cloqed when
the enlargement is brought into bl~cking engagement
with the valve seat.
In another embodiment of the invention the
duct outlet end has at least one exit opening in
the wall of the duct for discharging uelt in a lateral
direction. Allied with this, the ~alve member is,
for example, configured with a second enlargement,
at its said other end, the second enlargement being
a close fit in the duct outlet end and being cooper-
ative with the or each exit opening to control flow
therethrough during a control movement of the valve
member. Alternatively, the valve mer~er is configured
with a second enlargement which is a close fit in
the dùct outlet end, and a lateral pro~ection extends
from the second enlargement into the or each exit
opening ror controlling flow theretbrough. In either
case, the or each exit opening can be a longitudinally-
extending slot and melt flow therethrough can be
controlled by movements of the valve ~ember lengthwise
of the duot.
For simplicity in manufacture and in actuation
Or the valve member, flow control is ~ained by length-
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wise movement~ of the duct. However, the outlet end
of the valve member could be confi~ured - e.g. by
the provision of a rece~s or channel - so as to con-
trol flow through the or each exit op~ning in re~ponse
to rotary movements of the valve member.
Embodiments of the invention ~ill now be de-
scribed by way of example only with reference to
the accompanying drawings, in which:
Fig. 1 is a longitudinal sectional view through
teeming control apparatus forming a first embodiment
of the invention;
Fig. 2 is a fragmentary perspective view of
an outlet end of the first embodiment;
Figs. 3 and 4 are, respectively, a fragmentary
longitudinal sectional view and a perspective view
of the outlet end of a second embodiment of the in-
vention;
Fig. 5 is a longitudinal sectional view of
the outlet end of a third embodiment of the invention;
and
Fig. 6 is a longitudinal sectional view of
`, an alternative inlet or entry end which can be employed
` In any of the embodiments.
Referring to Figs. l and 2 of the drawings,
metal teeming apparatus 10 according to the invention
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is shown fitted to a metal pouring vessel 11. The
ves~el can be a tundish, ladle, degassing veQ~el
or other melt-containing vessel used in the metall-
urgical industry. Ves~el 11 is shown with a through-
wall, bottom-pour opening 12 in which the apparatus
i~ mounted. The said apparatu~ is suitably in-
stalled, leak-tightly to the bottou wall 14, e.g.
by cementing into place in a refractory lining of
the vessel 11.
The apparatus 10 comprises an elongate duct
or spout 15 through which melt is discharged into
a receiving vessel or mould, not shown, when a valve
member 16 in the duct is in an open position, a~
shown. The duct 15 has a melt entry end with a flared
or rounded mouth forming a valve seat 18. To co-
operate with the seat 18, the valve member 16 has
an enlargement 20 at one end. The valve member 16
is reciprocally movable in the duct 15, in a length-
wise direction. ~hen moved in one direction, the
valve member closes on the valve seat 18 and blocks
the duct to entry of melt, and when moved in the
other direction to uncover the seat, it opens the
duct for teeming of melt from the vessel. For leak-
tight sealing of the valve seat 18, the coacting
enlargement 20 has suitably rounded shoulders 21.
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AQ Qhown, the valve member iq lowered and raised,
respectively, to close and open the duct to flow
of melt.
The duct 15 is a unitary member devoid of
joints along it~ length between itQ entry end and
its opposite bullet end 22. Joints are avoided to
eliminate the risk of insufflation of air during
teeming.
The duct 15 has at least one melt exit opening
at the outlet end 22. In the embodiment of Figs.
1 and 2, there are two such opening~ 24, diametric-
ally opposed. In this example, the openings 24 are
formed as a pair of slots. These slot~ extend axially
in the wall of the duct, upwardly from the extreme
end thereof.
The lower end of the valve menber 16 is con-
figured to cooperate with the opening-~ 24 to control
flow of melt from the duct after the valve member
iq lifted from engagement with the seat 18. To this
end, the valve member has a second enlargement 26
at its lower or downstream end. The second enlarge-
ment is a close but sliding fit in the outlet end
22 of the duct 15. If the valve nember ic raised
and lowered, shorter or longer lengths of the slot-
~haped openings 24 are exposed to flow from the
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duct 15.
It will be observed that the ~econd enlargement
26 has an inclined or arcuate shoulder 28. ItA down-
ward and outward inclination assist~ in deflecting
melt flowing down the duct in lateral directions
out of the exit openings 24.
The two enlargements 20, 26 of the valve member
16 are interconnected by a narrower stem portion
29. The stem portion 29 and duct 15 are dimensioned
having regard for the size of the exit openings
24 to afford free passage of melt, at a desired
maximum rate.
Since the apparatus 10 is arranged for melt
to discharge in diametrically opposed lateral di-
rections, it is well suited for feeding melt intoa continuous slab caster mould.
The apparatus 10 can have a different outlet
end configuration, as illustrated in Figs. 3 and
4. Again, the apparatus has a duct 10 with two
opposed exit openings 24 in the wall thereof, and
a valve member 16 with a second enlargement 26
closely fitting the inside of the duct 15. In this
case, the enlargement 26 is transversely slotted,
at 30, to receive a transverse element 31. The ele-
ment 31 projects laterally from the enlargement
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26 forming two lugs or ears 32 ~hich are close,sliding fits in the re~peetive slotted exit openings
24. Each lug 32 has a downwardly-inclined top surface
33 to a~sist in deflecting flowing melt in lateral
directions out of the exit openings. The latter
have top end surfaces 34 which are sinilarly inclined.
A~ with the previous embodiment, the embodiment
of Figs. 3 and 4 affords control of flow from the
apparatu 10 depending on the position of the valve
member 16 in the duct 15. In a lovermost position,
the valve member closes the duct to entry of melt
from the vessel. When the valve m~mber is raised,
disengaging it from the seat, flow of melt can immed-
iately commence. The flow rate from the exit opening~
24 again decreases with raising of the valve member
16, as the effective size of each opening is progress-
ively reduced by the rising lugs 32.
Once more, this embodiment is well quited -
for teeminB melt into the mould Or a continuous
slab caster.
In both the foregoing embodiments, a lowering
of the valve member 16 to engage the valve seat
18 blocks the inflow of melt into the duct 15. At
the same time, the exit opening~ 24 are fully opened,
thus allowing melt already in the duct to drain
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away into a receiving vesQel or mould.
Fig. 5 show~q the outlet end of another embodi-
ment of the invention. In this caqe, the outlet
end has a form quiting teeming into the mould of
a continuous bloom caster. In this embodiment, the
duct 15 has a ~ingle exit opening 36. Opening 36
is at the very end of the duct 15 rather than in
its 3ide wall. The outlet end portion of the duct
is convergingly tapered at 37. The val~e member
15 in this instance does not have a second enlarge-
ment. In this case, its stem 29 ha-~ a tapered end
portion 38 generally matching the taper of the duct
outlet end portion.
It will be appreciated that in this embodiment
the configuration of the valve member at its lower
end portion 38 is such as to control flow of melt
through the exit opening 36. Raising and lowering
movements of the valve member 16 respectively will
increase or decrease flow from the opening 36. The
discharge flow direction will, of course, be axial
in this embodiment.
The embodiment illustrated in Fig. 5 has the
valve member 16 and outlet end portion 37 90 con-
figured as to allow melt to drain from the duct
15 when the valve member is lowered to engage the
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valve seat 18. To this end, the valve member is
undersized relative to the adjacent ~all of the duct so
as to leave an annular drainage clearance 39
therebetween when the valve member 16 is engaged with
the seat.
In Fig. 6 is shown an alternative form of inlet
end which may be incorporated in any embodiment of the
invention. The valve member 16 has an enlargement 20
similar to that shown in Fig. 1, but the duct 15 has a
flared mouth or trumpet 40. The trumpet facilitates
installation of the duct 15 in a frustoconical well
element 42 in the refractory lining ~4 of the vessel
11. A similar form of installation can be adopted for
the Fig. 1 arrangement, as indicated at the right hand
side of this Figure. The enlargement 20 and trumpet
coact as before for blocking the duct to entry of melt
from the vessel 11.
The duct and valve member can be made of any
material able to withstand the temperature and effects
of the melt. For controlled teeming of ferrous metals,
they can be made e.g. of aluminous refractory, for
instance in pressed and fired form.
Movement of the valve member to open and close
tho duct to melt, and to control flo~ rate therefrom,
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can be controlled by any convenient drive means D.
Such drive means D could comprise mechanical,
electrical pneumatic or hydraulic actuators. The dr~ve
means would ordinarily be linked in any suitable way to
the upper end of the valve member 16. The linkage
would thus have to extend through the melt and must be
able to withstand it, therefore. Accordingly, the
linkage could include a control rod made of, or coated
with, a refractory material.
The drive means could, in principle, be connected
to the other end of the valve member, via the terminal
end of the duct 15. This would be satisfactory, for
example, if the apparatus were installed in a side wall
of the vessel, adjacent its base, and if the duct had
an exit opening disposed in the side ~all of the duct,
facing downwardly.
In each of the foregoing embodiments, control
movements of the valve member 16 for controlling flow
rate are lengthwi3e movements. As indicated
hereinbefore, rotary control movements would be a
posslbility if the outlet end configuration of the
apparatus were adapted in ways which Yill be apparent
to the addressee.
Beneficially, the said drive means is arranged to
displace the valve member 16 continuously during a teem
by imparting a reciprocal, vibratory or oscillatory
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motion to it. By havin~ relative motion between the
valve member 16 and the duct 15, accumulation or
accretion of any inclusions in the melt between the
duct and valve member ~ill be hindered. The motion
imparted to the valve member can be of small amplitude.
Of course, if more convenient, the continuous motion
imparted to the valve member can be derived from a
separate drive means (~').
It will be appreciated from the preceding
description that the disclosed embodiments provide no
route by which air - or any other gas - may be sucked
into the apparatus lO by the flowing melt. Further,
the possibility of melt residing in the duct 15 and
possibly blocking it has been avoided, and the need for
particulate fillers has been eliminated. Flow of melt
can be terminated rapidly in an emergency and good
control over the teeming flow rate is attainable.
Moreover, the apparatus of this invention is of a
desirably simple construction which will facilitate
manufacture, assembly and servicing.
The component parts, namely the duct and valve
member can be economically manufactured. This is
beneficial since their service lives will be limited
owing to the aggressive environment to which they
inevitably are exposed.
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Industrial Applicability
The invention is applicable to the controlled
teeming, or pouring, of high temperature liquids, in
particular molten metals such as stainless steels, from a
vessel to a receiver such as a mould. By means of the
invention the flow of molten metal can be initiated and
terminated, or varied as to the rate of flow. Controlled
pouring by means of this invention can facilitate casting
operations, for instance in the continuous casting
process.
