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Патент USA US3078539

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Feb.'26, 1963
3,078,529
D. E. COOPER ET AL
MELTING CRUCIBLE AND COOLING MEANS THEREFOR
Filed April 24, 1959
4__
I_____I
. (46
INVENTORS’
Donald E. Cooper
Elmer D. Dilling
United States PatentO?lice
_,
3,078,529
Patented Feb. 26, 1963
1
2
3,078,529
jackets 2t) and 28, with such metal being transferred
through these jackets and through a heat exchanger ex
ternal of the crucible 10‘. Liquid metal from jackets 20
and 28 is transferred by electromagnetic pump 44-, which
MELTBNG CRUCIBLE AND COULING
MEANS THEREFOR
Donald E. Cooper and Elmer D. Dilling, Las Vegas,
Nev., assignors to Titanium Metals Corporation of
America, New York, N.Y., a corporation of Delaware
Filed Apr. 24, 1959, Ser. No. 808,811
is of conventional design and construction and is not here
described in detail, through pipe 46 which leads through
collar 22 as at 48. From the space between collar 22 and
the upper end of outer shell 18, liquid metal ?ows over
the top of shell 18 and around and down jacket 20 being
withdrawn through nipple 50. Flexible pipe 52 connects
This invention relates to a melting crucible, and more
particularly to a crucible and cooling means therefore for 10 nipple Sit to nipple 54 which leads the liquid metal into
jacket 28 from which it ?ows out through nipple 56 into
use in arc melting metals. Such crucibles are often re
?exible pipe 58. Pipe 60 connects pipe 58 to heat ex
ferred to as of the “cold mold” type.
changer 62 in which heat invthe liquid metal is abstracted
In cold mold arc melting furnaces, the crucible, or
conveniently by air forced by fan 64 passing over tubes
mold, itself is generally fabricated as a thin wall copper
66. Pipe 68 connects the heat exchanger to the intake
vessel surrounded by a jacket through which water is
of electromagnetic pump ‘44 which re-circulates the cooled
circulated as a cooling ?uid. An arc is maintained be
liquid metal back through the system. While the liquid
tween metal in the crucible and an electrode, which may
metal ?ow has been described above for purposes of
be consumable or non-consumable, and a solid ingotis
illustration, it will be apparent that the direction of liquid
for-med in the crucible by progressive solidi?cation of
metal ?ow through the system may be the reverse of that
molten transferred metal. Such apparatus is inherently
described with the same effects and advantages obtained.
dangerous because perforation of the crucible wall by the
Means are provided for attaching crucible 10/ to ap
are results in inflow of water onto hot and molten metal.
paratus for positioning and driving an electrode '70 and
v_A disastrous explosion can occur under such conditions.
which apparatus will be wholly or in part enclosed, the
In addition, Water cooled crucibles are di?icult to maintain
lower part of such enclosure represented in FIG. 1 by
at wall temperatures much above 100° C., the boiling point
shell '72 to which is attached extending ?ange 74. A
of water.
suitable gasket 76 is interposed between ?anges 74 and 14
It is therefore a principal object of this invention to
which are ?rmly tightened together by bolts 78‘ provided
provide an improved crucible and cooling means therefor
with insulating sleeves 80. Connection of one lead from
for use in arc melting furnaces of the cold mold type.
30 a power source to inner shell 12 may conveniently be
Another object of this invention is to provide a safe cruci
accomplished by terminal 82 which is tightened in elec
ble for use in arc melting furnaces of the cold mold type.
trical contact with ?ange 14 by one of bolts 78. The
A still further object of this invention is to provide an
electrode positioning and driving apparatus itself forms
improved crucible, for an arc melting furnace of the cold
mold type, having improved means for cooling and tem 35 no part of this invention and is referred to herein only
for ready understanding of the attachment of the crucible
perature control. These and other objects of this in
assembly thereto.
vention will be apparent from the following detailed de
The inner shell 12 may advantageously be of copper to
scription thereof and from the annexed drawings in which:
provide good heat transfer from its inner surface to the
FIG. 1 illustrates a general view of apparatus embody
ing features of this invention with the crucible shown in 4:0 liquid metal in jacket 29. The outer shell 18 is advan
tageously fabricated of steel. Due to temperature differ
a vertical sectional view.
ential, and different construction materials if employed,
FIG. 2 illustrates a sectional view of the apparatus of
the thermal expansion of inner shell 12 will be different
FIG. 1 taken along the line 2—2.
from that of outer shell 18. It is a unique feature and an
Referring to FIGS. 1 and 2, a crucible indicated gener
important advantage of the organization described that
ally at It} comprises an inner shell 12 having upper out
2 Claims. (Cl. 22-144)
wardly extending ?ange 14 and lower outwardly extending
differential expansion of these elements can occur without
?ange 16. Attached to one of these ?anges, for example,
the lower ?ange 16, as shown, is one end of outer shell 18
straining the construction which could result in serious
leaks of liquid metal. It is important that the top of outer
shell 18 be spaced apart from the under surface of flange
14 a distance greater than its longitudinal expansion in
which is spaced apart from inner shell 12, de?ning cooling
jacket 20. The top or other end, of shell 1-8 is not at
operation, thus providing clearance "for such expansion
tached to upper ?ange 14- but is spaced apart therefrom
and also providin0 a restricted passageway for liquid metal
as shown. _Depending from ?ange 14 and spaced apart
entering jacket 20. The liquid metal ?owing through
from and overlapping the top of outer shell 18, is collar
jacket 24} is thereby forced to ?ow close to the juncture of
22 which is?xedly attached as by welding to the outer
?ange l4- and the top of inner shell 12 to adequately cool
edge of ?exible, transversely a-rcuate ring 24, whose inner
this ordinarily critical area. Ring 24 is preferably fabri
edge is likewise ?xedly attached as by welding to shell
cated of relatively thin or ?exible metal and its trans
18 at a position spaced apart from its upper extremity.
versely arcuate design has the important effect of provid—
The lower end of crucible 10 is closed by provision of
ing ready ?exure across its width without strain on the
preferably detachable bottom 26 in which is provided a
cooling duct or jacket 28 in the area adjacent the interior 60 weldments by which it is attached to collar 22 and shell 18.
The liquid metal useful as a heat exchange medium is
of shell 12. Bottom 26 is attached to lower ?ange 16
preferably an alloy of sodium and potassium but may also
of inner shell 12 by provision of a slot pin and slot hinge
be lead, bismuth or other metal or alloy which is liquid
comprising horizontal pin 30, attached to arm 32, and
at the temperature of operation. An alloy of 54% sodium
which engages vertical slots 34 in spaced apart brackets
and 44% potassium is particularly ‘advantageous having
36 which extend from ?ange 16‘. Means for sealing the
a melting point of about 19° C. Sodium and potassium
bottom 26 to ?ange 16 are provided which comprise
particularly should not be exposed to air, and ignite read
gasket 38 interposed therebetween and maintained in
ily if leaks permit escape of metal to the atmosphere.
position by groove 40 in ?ange 16. Slots 34 provide for
Therefore the crucible of this invention provides for melt
vertical motion of bottom 25 so that when it is in closed
position it may be ?rmly tightened in place as by bolts 70 ing and discharge of an ingot without disconnecting or
breaking any cooling metal lines or joints.
42.
In operation, the crucible assembly of this invention is
Mean-s are provided for circulating liquid metal in
3,078,529
3
employed as part of arc melting apparatus which will in
clude mechanism for driving or positioning an electrode.
The electrode may be consumable or non-consumable.
maintained at high or low temperatures, than with Water,
Such mechanisms are well known in the art and will not
We claim:
1. In a crucible for use in are melting apparatus and
in which a liquid metal is employed as a ?uid coolant, the
herein be described in detail. Since the melting operation
will be carried out in an atmosphere of inert or other spe
cial gas, or under vacuum, the electrode driving mecha
nism will be enclosed, at least in part, in a suitable hous
ing, the bottom portion thereof, as previously described,
whose boiling point of 100° C. limits its useful applica
tions.
improvements which comprise; and inner shell having an
outwardly extending top ?ange and an outwardly extend
ing bottom ?ange, an outer shell surrounding said inner
shown as shell 72 and ?ange '74. The crucible it? is at 10 shell and having one of its ends ?xedly attached to one
tached to the driving mechanism and other auxiliary tappai
ratus by placing ?anges 74- and 14 in juxtaposition with
gasket 76 interposed therebetween, and bolts 78 are placed
of said ?anges, the other end of said outer shell being
spaced apart from the other of said ?anges by a distance
greater than the longitudinal thermal expansion of said
outer shell in operation to provide a passageway there
and tightened to provide a gas tight seal at the juncture ‘of
these furnace elements. The bottom 26 is set in closed 15 between, a collar ?xedly attached to said other ?ange and
position and sealed by tightening bolts 42.
The melting operation is then conducted according to
surrounding and overlapping the said other end of said
outer shell and spaced apart therefrom, a transversely
arcuate ?exible metallic ring ?xedly attached to said col
known methods. If the electrode '70 is consumable, the
lar and to said outer shell and means for circulating a
metal of which it is composed will be melted and trans
ferred to form an ingot in the crucible 10, the melting are 20 liquid metal coolant through the space between said inner
and outer shells, through the passageway between the said
being maintained by electric power connected by suitable
means (not shown) to electrode 78 and to the crucible and
other end of said outer shell and the said other ?ange and
metal therein through terminal 82 and ?ange 14 to inner
crucible wall 12. If the electrode is non~consumable, suit
able feed means will be provided to supply metal to be
through the space between said collar and said outer
shell.
melted to the arc zone, and a similar ingot obtained in the
crucible.
During melting the crucible is cooled by circulation of
liquid metal through the jacket 20‘ formed by inner shell
12 and outer shell 18 and through the jacket 28 in the cru
cible bottom. The liquid metal, preferably an alloy of
sodium and potassium, is circulated by electromagnetic
pump 44 through the crucible and also through heat ex
2. In a crucible for use in arc melting apparatus and
in which a liquid metal is employed as a fluid coolant,
the improvements which comprise; an inner shell having
an outwardly extending top ?ange and an outwardly ex
tending bottom ?ange, an outer shell surrounding said
inner shell and having one of its ends ?xedly attached to
one or" said ?anges, the other end of said outer shell being
spaced apart from the other of said ?anges by a distance
greater than the longitudinal thermal expansion of said
changer 62 so that its temperature at the supply point to
the crucible is as cool as desired. It will be ‘appreciated
outer shell in operation to provide a restricted passageway
that the speed of circulation of the liquid metal and the
and surrounding and overlapping the said other end of
said outer shell and spaced apart therefrom, a transversely
arcuate ?exible metallic ring ?xedly attached to said collar
amount ‘of heat abstracted therefrom by the heat ex
changer may be adjusted to maintain the proper crucible
therebetween, a collar ?xedly attached to said other flange
and to said outer shell and means for circulating a liquid
operating temperature, which may if desired be substan
tially higher than that normally maintained by water cir 40 metal coolant through the space between said inner and
outer shells, through the restricted passageway between
culation, but will be below any critical temperature im
posed by material employed in the fabrication of the cru
cible.
After melting is complete the ingot is preferably cooled
somewhat in place by simply continuing to circulate cool
ing liquid metal, and then the bolts 42 are loosened and
the said other end of said outer shell and the said other
?ange and through the space between said collar and said
outer shell.
References Cited in the ?le of ‘this patent
UNITED STATES PATENTS
the bottom 26 of the crucible is detached and swung down
on its hinge, and the ingot removed preferably down
wardly from crucible inner shell 12. After necessary
cleaning of the interior of crucible shell 12 the bottom 26
is swung up in place again and bolts 42 securely tight
ened and the crucible is ready for another cycle of melt
ing operation.
Employment of a liquid metal cooling medium, instead
‘of Water heretofore employed in crucibles for are melting, 55
provides a much safer apparatus. Occasionally the arc in
the crucible will Wander to, and perforate, the crucible
inner shell. If this occurs, when water is used as a cool
ing medium, entry of water into the crucible proper and
contact with molten metal therein can result in disastrous 60
explosion. The explosion hazard is eliminated when,
liquid metal is employed as a cooling medium as described
herein. In addition, better temperature control can be
1,112,937
1,936,280
1,988,425
2,357,780
2,392,267
2,665,318
Rowley _______________ __ Oct. 6,
Williams _____________ __ Nov. 21,
Summey _____________ __ Jan. 15,
Muller _______________ .. Sept. 5,
Salliover ______________ _- Jan. 1,
Herres ________________ __ Jan. 5,
1914
1933
1935
1944
1946
1954
2,761,002
2,762,097
Laird et al ____________ __ Aug. 28, 1956
Kruger ______________ __ Sept. 11, 1956
2,828,201
2,862,265
2,883,721
2,885,751
2,887,722
Findlay ______________ __ Mar. 25,
Vaughn et al ___________ __ Dec. 2,
Gorga et al. __________ __ Apr. 28,
Hornak et al __________ .. May 12,
Bauers ______________ __ May 26,
1958
1958
1959'
1959
1959
FOREIGN PATENTS
503,201
Great Britain _________ __ Mar. 31, 1939
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