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Patent 1130983 Summary

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(12) Patent: (11) CA 1130983
(21) Application Number: 333604
(54) English Title: METHOD AND APPARATUS FOR CONTINUOUSLY CASTING MOLTEN METAL
(54) French Title: METHODE ET INSTALLATION DE COULEE CONTINUE DU METAL
Status: Expired
Bibliographic Data
(52) Canadian Patent Classification (CPC):
  • 22/167
(51) International Patent Classification (IPC):
  • B22D 11/00 (2006.01)
  • B22D 11/18 (2006.01)
  • B22D 41/50 (2006.01)
(72) Inventors :
  • THOMSON, ROBERT (Canada)
(73) Owners :
  • HER MAJESTY IN RIGHT OF CANADA AS REPRESENTED BY THE MINISTER OF ENERGY, MINES AND RESOURCES (Not Available)
(71) Applicants :
(74) Agent: LEMON, F.W.
(74) Associate agent:
(45) Issued: 1982-09-07
(22) Filed Date: 1979-07-18
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data: None

Abstracts

English Abstract


TITLE
A METHOD AND APPARATUS FOR CONTINUOUSLY CASTING MOLTEN METAL
INVENTOR
ROBERT THOMSON
ABSTRACT
A method of continuously casting molten metal in
a reciprocable mould sealed to a vessel containing liquid
metal by means of an extendible container, wherein a tube
forming a passage from an orifice in the vessel to the mould
is sealed at one end to the vessel, and at the other end
dips into molten metal in an entry to the mould. A meniscus
of molten metal around the tube and in the mould is stabilized
by adjusting the pressure of inert gas fed into the extendible
container so that the rate of flow of metal from the vessel
to the mould is controlled directly by the rate of extraction
of the solidifying casting from the mould. The problems
related to controlling metal flow into the mould are substan-
tially reduced. This is of particular significance in continu-
ous casting steel, permitting the casting rate to be indepen-
dent of the size of the orifice in the vessel, and of the
ferrostatic head above it. Thus it is possible to use a
larger orifice in the vessel, alleviating the problem of
nozzle blockage, and to continuously cast aluminum killed
steels where deoxidation by and alloying of aluminum is
achieved in the vessel or during prior refining stages of
preparation of the molten metal.


Claims

Note: Claims are shown in the official language in which they were submitted.



CLAIMS:

1. In the method of continuously casting aluminum
killed steels and alloys, as molten metal, by pouring
the molten metal, by means of a static head of molten
metal in a vessel, from an outlet orifice in the vessel
into a reciprocable mould through an extendible chamber
shrouding the path of the pouring molten metal and sealing
the vessel to the mould, while inert gas is being fed into
the extendible chamber, and which includes:
a) causing the molten metal flowing through the
vessel outlet orifice to flow through a molten metal static
head containing tube of refractory material in the ex-
tendible chamber, the tube having one end sealed to a portion
of the vessel extending around the orifice and the other end
immersed in molten metal in an entry to the mould with a
meniscus of molten metal in the entry to the mould and around
the tube, and
b) supporting to a sufficient extent the static
head of molten metal in the vessel and the tube, by means
of the pressurized inert gas in the extendible chamber and
on the meniscus of molten metal, to maintain the tube filled
with molten metal flowing substantially at the same volumetric
rate as the casting rate in the mould, the improvement
comprising:
c) the outer orifice has a diameter greater than
31.7 mm, and
d) the casting rate is controlled substantially
by the volumetric rate of extraction of product from the
reciprocable mould.


2. In the combination of apparatus for continuous
casting aluminum killed steels and alloys, as molten metal,
comprising, a vessel for the molten metal, the vessel having



CLAIMS CONT.
an outlet orifice for molten metal to flow therethrough
from the vessel under a static head, a reciprocable mould
for receiving the molten metal when it is flowing through
the outlet orifice, an extendible chamber shrouding the
path for the flowing molten metal and sealed to the vessel
and the mould, and means for feeding pressurized inert gas
into the chamber, and wherein there is provided:
a) a molten metal static head containing tube of
refractory material in the extendible chamber, the tube
having one end sealed to a portion of the vessel extending
around the orifice, for receiving the molten metal when it
is flowing therethrough, and the other end positioned for
immersion in molten metal in an entry to the mould with a
meniscus of molten metal therearound in the entry to the
mould, and
b) means for adjusting the pressure of the inert
gas, feed to the extendible chamber for, in operation, sup-
porting a static head of molten metal in the vessel by the
pressure of the inert gas on the meniscus of molten metal,
whereby, in operation,
c) the tube is maintained filled with molten metal
flowing therein substantially at the same volumetric rate
as the casting rate in the mould, the improvement comprising,
d) the orifice has a diameter greater than 31.7 mm,
whereby
e) the casting rate may be controlled substantially
by the volumetric rate of extraction of product from the
reciprocable mould.

16

Description

Note: Descriptions are shown in the official language in which they were submitted.




This invention relates to a method and apparatus
for continuously casting me-tal.
It has already been proposed in Unlted States
Pa-tents Nos. 3,~02,757, dated Sep-tember 24, 1968, :t.M.D.
Halliday, and 3,840,062, dated October 8, 197~, M. P. Kenney,
to provide a flexible chamber joined at one end to a tundish
and at the other end to a mould capable of being reciprocated.
During casting, molten metal flows freely from an orifice in
the tundish, down a central por-tion of the chamber bore and
into the mould, while an inert gas blanket at atmospheric
pressure or about 1.5 psi is circulated around the molten
metal and in the chamber to exclude and remove oxycJen and ;'
gases containing oxygen and thus inhibit oxide formation
except as is incidental to the cooling and freezing of the
metal in the mould itselE. In similar disclosures, by
Schrage - U.S. Patent No. 3,563,299 dated Feb. 16, 1971
Pollard - U.S. Patent No. 4,023,61~ dated May 17, 1975
Kashuba - U.S. Patent No. 3,833,050 dated Sept. 3, 1974
and ~yman - U.S. Patent No. 3,572,422 dated March 23, 1971
contained and purging gases at slightly above atmospheric
pressure are introduced on and around the free-falling pouring
stream of metal to minimize re-oxidation of the metal.
Whi~e these proposals may overcome the problems
of oxidation of the pouring stream, a problem still exists
in that the orifice in the tundish has to be suf~
ciently small in the cross-section to control the
rate of volumetric flow of liquid metal into the
mould to match the rate of casting from the mould, and
this small size range of orifice, for example between

9.5 mm and 25.4 mm diameter J makes the orifice highly

susceptible to partial or complete blocking by aluminous
deposits from the metal, necessitating frequent shut-
downs, or, the elimination of those elements inducing

. ~ ~

~3~g~3~

blocking (Al, Ti, Zr, etc.) from the pre-treatment procedures
used to refine the li~uid metal.
It would be desirable to provide a me-thod of
continuously casting molten metal wherein the rate of
volumetric flo~ of the liquid metal into the mould is not
.controlled by the cross-sectional area of. the orifice in
the tundish because this would allow an orifice of greater
cross-section to be used and thus alleviate the problem
associated with partial blocking of the orifice.
According to the present invention there is
provided in the method of continuously casting aluminum killed
steels and alloys, as molten metal,by causing the molten metal
to flow, by means of a static head of molten metal in a vessel,
rom an outlet orifice in the vessel into a reciprocable
mould through an extendible chamber shrouding the path o~ the
pouring molten me-tal and sealing the vessel to the mould,
while inert gas is being fed into the extendible chamber~ and
which includes,
a) causing the molten me-tal flowing through the
~0 vessel outlet orifice to flow through a tube of refractory
material in the extendible chamber, the tube having one end
sealed to a portion of the vessel extending around the orifice
and the other end immersed in molten metal in an entry to the
mould with a meniscus of molten metal in the entry to the
mould and around the tube, and
b) supporting a static head of molten metal in
the vessel and the tube, by means of the pressure of
pressurized inert gas in the e~tendible chamber and on the
meniscus of molten metal, to maintain the tube filled with
molten metal flowing substantially at the same volumetric
rate as the casting rate in the mould, the improvement

comprising,
c) the outlet orifice has a diameter greater


2 -

~13~ 3
than 31.7 mm, and
d~ the casting rate ls controlled substantially
by the volume-tric rate of extraction o~ product from:the
reciprocable mould.




~




~ ~ .
.. .



Further according to the present inven-tion
there is provided in the combination o~ apparatus for
continuously casting aluminum killed steels an~ alloys, as
molten metal comprising,a vessel for the molten metal, the
vessel having an outlet orifice for molten metal to flow
therethrough from the vessel under a static head, a recip-
rocable mould for receiving the molten metal when it is
flowing through the outlet orifice, an extendible chamber
shrouding the path for the flowing molten metal and sealed to
the vessel and the mould, and means for feeding pressurized
inert gas into the chamber, and wherein there is provided,
a) a molten m~tal static head containing tube of
refractory material in the extendible chamber, the tube
having one end sealed to a portion of the vessel extending
around the orifi.ce, for receiving the molten metal when it
is flowing therethrough, and the other end positioned or
immersion in molten metal in an en.try to the mould with a
meniscus of molten metal therearound in the entry to the
mould, and
2r) b) means for adjusting the pressure of the inert
gas feed to the extendible chamber for, in operation, support-
ing a static head of molten metal in the vessel by the
pressure of the inert gas on the meniscus of molten metal,
whereby, in operation
c) the tube is maintained filled with molten
metal flowing therein substantially at the same volumetric
rate as the casting ratP in the mould, the improvement
comprising,
d) the orifice has a diameter greater than
31~7 mm, whereby
e) the casting rate may be controlled substantially
by the volumetric rate of extraction of product from the
reciprocable mould~

A ~ 3

113~ 3

In the accompanying drawings whlch illustrate
prior art and, by way of example, embodiments of the present
invention:
Figure 1 is a diagrammatic, sectional side view
of portions of conventional apparatus for continuously


/


' /




- 3A -
~`'. .

9~33

casting molten metal, and
Figure 2 is a diagrammatic, sectional side view
of portions of an apparatus according -to the present inven-
tion for continuously casting molten metal.
In Figure l there is shown an apparatus for contin-
uously casting molten metal comprising a vessel l for molten
metal 2, the vessel having an outlet orifice 4 for molten
metal 6 to flow therethrough from the vessel 1 under a
static head, a reciprocable r cooled mould 8 of known type
for receiving the molten meta~ 6 when it is 10wing through
the outlet orifice 4, an extendible chamber 10 shrouding
the path for the flowing molten metal 6 and sealed to the
vessel 1 and the mould 8, and means 12 and 13 for feeding
pressurized inert gas to thè chamber lO.
In operation, molten metal ~lows from the vessel l
through the outlet orifice 4, as a xee-falling stream of
molten metal 6, into the mould 8 where it is continuously
cast into a rod and pulled therefrom by a conventional extrac~
tion device ~not shown). Pressurized inert gas, e.~. nitro-
gen, at slightly above atmospheric pressure, is fed into the
chamber lO to blanket the stream o molten metal 6 from atmos-
pheric oxygen and minimize re-oxidation oE the molten metal 6.
The free-falling stream of molten metal 6 exits
from the vessel 1 through an orifice 4, the cross-sectional
area of which is governed by the rate of flow of metal
therethrough having to match the rate at which metal is
cast in the mould 8. This results in the cross-sectional
area of the orifice 4 being small enough to be subject to
blocking by oxides being deposited therein.
3n Referring now to Figure 2, similar parts to those
shown in Figure l are designated by the same reference

numerals and the previous description is relied upon to
describe them.

:~3~9~3

In this embodiment the outlet orifice 4 has a

oriEice diameter greater than 31.7 mm and is located
above a sliding ceramic plate 14 which is a gate of a type of
gate valve known in the art as a slide gate 16. The
function of the slide gate 16 is to close off and open the
path from the orifice 4 to the mould 8. A molten metal
head containing tube 18 of refractory material is in the
extendible chamber 10. The tube 18 has one end 20 sealed to
a portion of the vessel 1 extending around the orifice 4

via the slide gate 16, for receiving molten metal 6 when it
is flowing through the orifice 4, and has t~e other end 22
positioned for immersion in molten metal 24 in an entry 26
to the mould 8 with a meniscus 28 of molten metal therearound
in the entry 26 to the mould 8.
The extendible chamber 10 comprises a 1exible
bellows sealed to the vessel 1 and to the mould 8 by gaskets
30 and 32 respectively. The means 12 for feeding pressurized
inert gas into the chamber 10 is provided with a solenoid
valve 34. An inert gas outlet 36 is provided for the chamber

10 and the outlet 36 has a solenoid:valve 38. The tube 18
is preferably made of a refractory material of high thermal
shock resistance such as fused silica or graphitized alumina
marketed by Vesuvius Crucible Company o Pittsburg, U. S. A.
The end 22 of the tube 18 preferably extends into the molten
metal 24 to a depth in the range 25 mm to 50 mm.
The level of the meniscus 28 may be detected ~y one
of several known detection means, e.g. by using a y-ray
source 40 and detector 42 external to the mould 8, or by thermo-

couples 44 embedded in the mould 8, and such level detection

means,are usbd to automatically control, via solenoid valves
34 and 38 the absolute gas pressure in the extendible chamber
10, by admittîng inert gas through valve 34 from a pressurized
inert gas source (not shown) when the level of the meniscus 28

~13 ~`
-- 5 --

- ~IL13~33

rises too high, and by opening valve 38 to release inert gas
from the extendible chamber 10 to a low pressure chamber
(not shown) or to atmosphere when the level of the meniscus
28 is detected as being below a desired level, In this
manner the ferrostatic head 'h' cf molten metal 6 in the
vessel 1 and the tube 18 may be continually and automatically
more or less balanced by the pressure of enclosed gas acting
on the meniscus 28.
In practice the controlled pressure of the inert
gas in the extendible chamber 10 is subjected to disturbance
by the heating effe'ct on the inert gas of molten metal 6
passing through the tube 18, and by the compression/expansion
effect occasioned by the reciprocating action of the recipro-
cable mould. In this embodiment these disturbances are
corrected or by incorporating in the pressure control
system a sensitive pressure transducer 46, from which a time
derivative signal is obtained dt and used to actuate
valves 34 or 38 in anticipation of pressure fluctuations of
the înert gas from the inert gas pressure determined by the
meniscus level detection means. In this manner any cyclic
variation in pressure of the inert gas from the mean pressure,
or the drift of pressure away from the mean pressure, are
both adequately negated. In a likewise manner, the above
mentioned pressure control system automatically adjusts the
absolute pressure of gas at the meniscus to compensate for
changes in Dh" occurring as the level of the molten metal 2
in the vessel 1 changes during the course of casting, i.e.
decreases during casting, or increases b~ additional molten
metal being supplied to vessel 1~
The tube 18 is maintained filled with molten metal
flowing therein subst:antially at the same volumetric rate as

the casting rate from the mould 8, and such flow is controlled

~13~83

sole].y by the volumetric rate of extraction of product from
the mould 8.
The reciprocable mould 8 is a known -type of mould
which may be reciprocated in relation to the casting during
opera-tion.
The extendible chamber 10 comprises a cylindrical
section 48, a bellows section 50 and a disc-shaped end wall
5~, with sealed flanges.
In the embodiment in Figure 2 the bore of the tube
18 is shown of constant cross-section, but in other embodiments
of this invention the tube 18 may be any suitable shape that
is appropriate to the size and shape of the product being cast.
Thus the present inven-tion is not restricted to us.Lng tubes
18 having bores of constant cross~section but includes tubes
18 having for example, a funnel shape bore wh.ich rnay be
round or rectilinear in cross-section.
In operation, molten metal, e.g. molten steel r
is continuously cast by introducing the molten metal 2, by
means of the static head "h1' of molten metal, from the outlet
orifice 4 in the vessel 1 into the reciprocable mould 8
through tube 18 in the extendible chamber 10, shroudin~
the path of molten metal 6 and sealiny the vessel 1 to the mou].d
8, while inert gas, e.g. nitrogenr is being fed by ~he feed
pipe 12 into the extendible chamber 10 at a suitable pressure
for the inert gas pressure "P" on the meniscus 28 to maintain
tne tube 18 filled with molten metal 6 flowing substantially
at the same volumetric rate as the casting rate in the mould 8.
In order to maintain the meniscus 28 of molten metal
in the entry portion of the mould 8 and around the end of
the tube 18 as the mould 8 reciprocates about a mean position
the fluctuations in pressure in the extendible chamber 10

~L3~3

induced by such reciprocation of the mould 8 may be compensated
for by actua-ting the solenoid valves 34 and 38 in response
to movements of the reciprocable mould 8~ A different
means of maintaining a predetermined gas pressure in the
extendible chamber 10 comprises incorporating in the wall of
the extendible chamber 10 a different bellows design to
that shown in Figure 2 and designated 50. The different
bellows having the characteristic that the volume enclosed
by the bellows is at all times substantially constant
irrespective of the degree of compression or expansion of
the bellows within the limits set by the reciprocation of
the mould 8. This substantially constant volume ~haracter-
istic may be achieved by constructing triangulated segments
of the bellows wall oE an elastic heat resistant material/ as,
for example, certain high temperature polymeric materials.
Through these, and possibly other means known in the art,
the variations in pressure in the chamber, due to the piston-
like movemenk of the mould 8, may be substantially reduced
to produce an acceptably small oscillation of the level of
the meniscus 28. In practice, such permissible ~ariations
in the level of the meniscus 28 will be in the range of
~0.125 to ~0.25 ins. (~3 m.m. to ~ 6 m.m.).
When molten steel is being cast, the pressure P psi
in terms of "h'l ins. may be expressed as
P = 14.7 ~ 0.27 h
with P controlled to ~0.1 psi.
In existing continuous casting machine designs for
steel casting, to which machines embodiments of the present
invention may be added with a minimum of disturbance of
existing equipment and practices, the distance "h", ma~ be
of the order of 25 to 50 ins. (63.5 to 127 cm~. Thus the

incorporation of the proposed improved method wou:Ld require
absolute enclosure pressures in the range 20 to 28 psi

~13~ 33

approxîmately.
By the present invention, it is possible to cast
from the vessel 1, grades of steels and alloys which are
aluminum killed or deoxidized at some previous stage of
metal preparation, and it is no longer necessary to add
aluminum directly into the mould 8. The reason why mol-ten
aluminum killed steels can be cast by~the present invention
in this manner is because a much larger orifice 4 can be
used, i.e. a size of orifice 4 can be used which will not be
susceptible to blocking by deposition of aluminous inclu-
sions on its walls. By way of example of this, it is well
known in the art that an aluminum treated steel in the
vessel 1 having a residual aluminum level of O.Q4 wt. per
cent will cause blocking of the orifice 4 unless the diameter
of the latter is greater than around 1~ ins. (31.7 mm).
The free flowing delivery rate of steel, flowing under gravit~,

is so great through an orifice of this size that prior
to the present invention only very large slabs could be
cast of aluminum bearing steels. By contrast, the
smaller nozzle orifices of 0.625 (41.3 mm) in diameter

used prior to the invention to control liquid metal 1OW
in casting smaller billets in the size range 4 x 4 in.
(10.2 x 10.2 cm) to 6 x 6 in. (15.2 x 15.2 cm) would
block the orifice 4 quickly if aluminum treated steel was
used in the vessel 1. Since with the present invention,
neither the size of the orifice 4 nor the pressure of
the gas in the extendible chamber 10 controls molten metal
flow, it is possible to use a larger orifice 4 than could




_ g _




: '

~13~33

previously be used so that the accwmulation of aluminous
oxides in the orifice 4 is tolerable, and cannot
attain such a severity as to completely block the larger
orifice 4. Partial blocking of the orifice 4, which pre-
viously catastrophically reduced the rate of flow of mol~en
metal from the vessel 1 through the orifice 4 to the mould
8, is no longer of any consequence since the flow of
li~uld metal through a part1ally blocked larger oriflce 4
is adequate for small to medium billet sizes and is controlled
solely by the rate of removal of the semi-solid casting
from the mould 8.
Thus the main advantacJes of the present invention
can be sùmmarized as ~ollows:
1.) An orifice of larger diameter that previousl~
and not susceptible to blockage of the orifice 4 can be
used to cast the smallest sizes of billets of commercial
interest from fully deoxidized steels and steel alloys -
contained, in vessel 1, for example, from steels which have
been pre-alloyed with ~uantities of Al, Ti, Zr, B, N. etc.
2.) The casting rate is a separate controllable
parameter in the process, and is no longer, as with prior
process, dependent on the size of the orifice 4. In the
prior art the rate of flow of metal through the orifice 4
directly determined the casting rate of product leaving the
mould 8. With the present invention, the operator-chosen
casting rate of product determines the rate of flow of
liquid metal through the orifice 4.



-- 10 -- !

3~33

3.) Using an inert gas in the extendible
chamber 10 at ~ 25 psi prevents any ingress of atmospheric
oxygell and therefore eliminates o~idation of the metal
between the vessel 1 and the mould 8.
4.~ The pressure exerted on the meniscus 28 by
the inert gas above it in the extendible chamber 10 will be
advantageous in improving the heat transfer between the outer
surface of the solidifying casting and the wall of the mould
8. This advantage arises because the natural tendency of the
hot solidified shell of the casting to contract and shrink
away from the wall of the mould 8 will be resisted by the
increased hydrostatic forces of the molten metal acting on
the wall of the mould 8 from the li~uid metal inkerior, and
tending to bulge the solidifyiny shell outward toward the
wall o the mould 8. As is well appreciated in the art,
any decrease in the air-gap between the wall of the mould 8
and the surface of the molten metal being cast such as
that obtained by the present invention by pressurization of
the liquid core of the casting, will increase the rate of
heat transfer between the molten metal being cast and the
mould 8, producing greater solidification rates in the casting.
Thus by producing greater solidification rates, the present
invention will permit significantly advantageous lncreases
in casting rate of all products, whether aluminum treated
or not.
Another advantage of the present invention relates
to the problem in the art of providing efficient lubrication
of the wall of the mould 8 to prevent the newly formed,
moving casting skin sticking to and tearing on the wall of
the mould 8. Thj.s undesirable phenomenon of mould-casting

9~3

interEacial fric-tion is kept under control in the art by
continuously introducing an oil film Gn the wall of the mould
8 above the meniscus 28 of molten me-tal. In the prior art,
capillary forces and gravity have caused the oil film to
spread downwards past the meniscal line into the area of
mould-cas-ting contact. In the present invention this spreading
of the lubricant downwards is considerably and advantayeously
enhanced by the effect of the pressurized inert gas above
the meniscus 28, forcing oil down the wall of the mould 8
into the lower reaches of the wall of the mould 8, which are,
of coursel at atmospheric pressure only.
In addition to improving operational aspects of
continuous casting aluminum deoxidized steels by improving
castin~ rate and decreasing mould-billet friction~ the present
invention has the additional advantage o widely incxeasing
the acceptable range of casting temperature of metal which
can be used, since the rate of casting is now an ind~pendent
~ariable. This may be explained by the following generalized
description of the prior art and the possibilities inherent
in the present invention. In the prior art, the optimum
casting rate (Vo) is associated and determined by the heat
transfer characteristics of the mould 8, (Ho)/ and the
optimum metal superheat (To). The diameter of the oriice 4
that is used is precisely that which will supply the liquid
metal at a volumetric flow rate (Vo) at superheat ~To). Let
the diameter of the orifice 4 be (Do). All of these parameters,
in the prior art, are inter-dependent, and a variation of one
of them outside narrow limits will cause failure of the
process~ For example if the superheat ~To~ falls to ~T)~
(To > T,~ the fluidity of the steel through the orifice 4
having a diameter tDo) is reduced and ~Vo) decreases to

(V1)O In one ex~reme~ with ~T <<To), for example, for steel
(To - T > 100 C) the thermal losses at -the orifice 4 may



- 12 _

3L~ 9i~33

may cause complete closure of the orifice 4 and a cessation
of pouring and cas-ting. ~-t the other extreme, if the
superheat (To) is greater than optimum, (T > To), the
rate of flow through the orifice 4 having a diameter (Do)
will be slightly increased, but more importantly the
dwell time of metal in the heat exchange zone of the mould 8,
now operating at (Ho~ or slightly higher, will not be long
enough to dissipate the extra superheat, and less solidi-
fication will occur, so that an inadequately thickenecl ingot
1~ shell is formed which will rupture at the exit of the
mould 8 and a break-out of molten metal will occur. This
cannot be avoided by reducing (Vo) since.(Vo) is conditioned
solely by (Do). Thus in practice~ excursions of liquid
metal superheat from (To) can lead to proc~ss f~ilure with
the prior art.
Witk the present invention, a wide range of
values of (To), (Do) and (Ho), and (Vo) can be usefully
combined to greatly reduce system stoppages. (V~ can be
varied independently of (Do), so that for example if the
superheat of the molten metal is higher than what was
optimum by known process, then (V) can be unilaterally
reduced to afford the metal sufficient dwell time in the
mould 8 to form a safe, solidified shell at the exit of the
mould 8 which will not rupture. If the superheat (To) is
less than optimum, then no longer does a small orifice 4
cause flow stoppage, because, with the present invention,
the orifice diameter (Do) can be made many times greater in
magnitude than the cross-sectional area of the orifices 4 of
the prior art~
In summary then, a useful advantage of the present
invention is -to permit the successful continuous cas-ting of

bodies of liquid metal having a wider range of casting



temperatures than could be used hitherto. Furthermore, with
the prior art only small variations in orifice diameter r
(Do), are permissible because a reduction in ~Do) due to
nozzle blockage, or increase in (Do) by nozzle erosion, will
both directly affect the casting rate and interfere with
the con-tinuity of the casting process. With the present
invention, the orifice size ~Do) is of minor or negligible
significance to the operation of the process.

~.




- ~ 1~ '--

Representative Drawing

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Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date 1982-09-07
(22) Filed 1979-07-18
(45) Issued 1982-09-07
Expired 1999-09-07

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1979-07-18
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
HER MAJESTY IN RIGHT OF CANADA AS REPRESENTED BY THE MINISTER OF ENERGY, MINES AND RESOURCES
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Drawings 1994-02-22 2 129
Claims 1994-02-22 2 85
Abstract 1994-02-22 1 40
Cover Page 1994-02-22 1 18
Description 1994-02-22 16 670