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Патент USA US3019287

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Jan. 30, 1962
A. LORENZ
3,019,275
APPARATUS FOR HEATING MOLTEN METALS IN A VACUUM CHAMBER
Filed Nov. 24, 1958
2 Sheets-Sheet 1
ELECTRICAL
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DIFFERENTIAL &
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MECHANICAL
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Jan. 30, 1962
A. LORENZ
3,019,275
APPARATUS FOR HEATING MOLTEN METALS IN A VACUUM CHAMBER
Filed Nov. 24, 1958
2 Sheets-Sheet 2
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FIG 2
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United States Patent '0
1
7
3,019,275
Patented Jan. 30, 1962
2
when read with reference to the accompanying drawings,
3,019,275
APPARATUS FOR HEATING MOLTEN METALS
IN A VACUUM CHAMBER
Albert Lorenz, Hanan (lVIain), Germany, assignor to
W. C. Heraeus G.m.b.H., Hanan (Main), Germany,
a corporation of Germany
_ Filed Nov. 24, 1958, Ser. No. 775,791
in which
FIGURE 1 shows diagrammatically and partly in sec
tion one preferred embodiment of the present invention;
while
FIGURE 2 shows a cross section taken along line
A--A of FIGURE 1.
Claims priority, application Germany Nov. 26, 1957
Referring to the drawings, the container or ladle 1
holds the molten metal 2 from which the gases occluded
10 therein are to be expelled by means of the gas-extrac
The present invention relates to a method and appara
tion apparatus 3 which is partly immersed from above
10 Claims.
(Cl. 13-31)
'
tus for heating metals, and especially steel, for the pur
pose of extracting the gases therefrom.
Prior to this invention the gases occluded in molten
into the metal bath.
This apparatus consists of an ex
traction chamber 5 which is continuously evacuated
through a pipe 4 leading to a pump and control valve
metals, especially steel, were extracted therefrom by pass 15 unit 4’. Chamber 5 has a pair of pipes 6 and 7 extend
ing the metals in a continuous flow through an evacuated
ing vertically downward therefrom and into the bath of
chamber. Numerous efforts were then made to improve
molten metal 2 at a considerable distance from each
such gas extraction by further heating the metals while
other. By injecting a gas through a pipe 8 into inlet
the extraction process was being carried out. This was
pipe 6, a continuous flow of metal will be started and
done by providing arc-heating or resistance heating means 20 maintained, rising from the bath in ladle 1 through pipe
within the closed evacuated chamber or by making a
6 into chamber 5, and then ?owing through this cham
part of such chamber in the form of a crucible and sur
ber toward the return pipe 7 and through the latter back
rounding such part with an induction coil. However,
into the bath in ladle 1. The gas bubbles then rising
these prior methods either do not operate safely and
in pipe 6 will take along the metal and convey it up
reliably or only very inefficiently since they do not heat 25 wardly into the actual extraction chamber 5. The gas
up the entire mass of the metal flowing through the evac
supply may be’ regulated by a suitable valve mechanism
uated chamber, but only a small part thereof, that is,
8’. A suitable hopper 9 or the like containing alloying
either only the surface of the metal or only a negligible
constituents is also connected to chamber 5 for supply
amount in comparison to the volume of the ?ow.
ing these materials to the ?ow of metal passing through
it is an object of the present invention to provide a 30 the chamber. Hopper 9 is likewise adapted to be sealed
new and surprisingly simple method of heating up the 7 hermetically toward the outside, and it is provided with
flow of molten metal within the evacuated chamber for
suitable means, as diagrammatically indicated at 10 in
the purpose of increasing the ei?ciency of the gas ex
FIGURE 1, for controlling the supply of these alloying
traction considerably over the methods hitherto employed.
constituents into chamber 5.
A further object of the invention consists in‘the pro 35
The gas extracting apparatus as such is enclosed by a
vision of a new apparatus for heating up the flow of
molten metal while passing through the evacuated ex
traction chamber by inducing electric currents within
metallic covering 11 which is adapted to take up the out
' side pressure acting upon the apparatus, and it is provided
at the inside with a lining of refractory material. Cov
ering 11 also extends around the intake and return pipes
manner.
f
40 6 and 7 to a point closely above the surface of-the bath
Instead of merely heating up a small portion of the
of molten metal 2 in ladle 1. Thus, the pipe portions
?ow of molten metal within the evacuated extraction
extending into the bath of metal only consist of refrac
chamber, the present invention provides for a thorough
tory material and are carried by the metal covering 11.
heating of the entire volume of the ?ow, of metal. For
Interposed between the inlet and return pipes 6 and
this purpose, the present invention utilizes a gas ex 45 7 is a practically closed iron transformer core 12 which
tracting apparatus of the type in which the molten metal
also carries a primary coil 13 which is supplied with an
is withdrawn from a containerholding the metal. along
alternating current of a standard line frequency. By
one path, then passed through an evacuated extraction
means of this transformer core 12 a very strong alternat
chamber, and ?nally returned to the container along a
ing current will be induced in the molten metal flowing
second path which is spaced from the ?rst path. Ac-v 50 from the bath 2 in ladle 1 through inlet pipe 6, chamber
cording to the invention, electric heating currents are then
5, and return pipe 7 back into bath 2. The path of the
produced by induction within the entire amount of molten
current in the metal bath 2 is indicated in FIGURE 1
metal of such circulation. This is attained by the pros
by the dotted line 14. Since the cross-sectional area of
vision of a transformer, the secondary circuit of which
the bath itself is very large, the resistance incurred by
is formed by the ?ow of molten metal and the closed 55 the current passing therethrough is very small. As the
core of which passes between the two mentioned paths
metal covering 11 of the apparatus does not extend en
of the flow of metal and carries a primary induction
tirely to the surface of the metal bath 2, there is no dan
coil which is energized by an alternating ‘current of a
ger of a short circuit of the induced current due to such
standard frequency. As soon‘as the molten metal ?ows
covering. Within the extraction chamber 5, however,
over from the first or intake path into the second‘ or 60 the molten metal flows from inlet pipe 6 to return pipe 7,
return path, the secondary circuit of the transformer will
and during such passage it strongly sprays and spatters.
be closed and itthereby reacts upon the current ?owing
The cross-sectional area of the molten metal which is
through, the primary coil. The beginning of this reac~
present at this passage at all times is therefore relatively
tion may be utilized for indicating the beginning of the
small, with the result that the electric resistance and the
continuous gas-extraction process, and the strength of 65 heating effect produced within the metal in the chamber
this reaction upon the primary current produced by a
itself is very high.
stronger or weaker flow of molten metal may also be
The heat is therefore generated primarily within the
utilized for effecting and controlling the gas~extraction
upper part of the heated path 2»—6—5--7—2 of the
process.
molten metal. This, however, is the place where only a
These and further objects, features, and advantages 70 small amount of the molten metal is separated from the
of the present invention will become more apparant from
great mass of the bath 2 and Where it is therefore to be
the following detailed description thereof, particularly
expected more than at any other place that the molten
such ?ow of molten metal in a new and highly improved
‘ 3,019,215
4
suspending said vacuum chamber above said container
metal will cool off or may even solidify. On the other
molten metal passing through the apparatus always has
and for raising and lowering the same relative to said
container and for immersing‘: the free ends of said con
duits into said molten metal, means for evacuating said
chamber and the unimmersed parts of said conduits above
the surface of said molten metal Within said container,
means for conveying the molten metal through said inlet
conduit into said vacuum chamber, and means for in
ducing a strong electric current in the entire volume of
ammeter 15. This serves as a clear indication of the fact
induction means comprise a transformer having a sub
be about 100 kw. or more may, however, to a certain
secondary circuit of said transformer.
hand, this is also the point Where relatively cold alloy
ing constituents may be added from the hopper 9 by
its feed control device 10‘. It is therefore necessary that
the heat required for melting or dissolving these additions
will also be supplied at this point.
The most important requirement for carrying out the
method according to the invention is the fact that the
to form a closed electric circuit. Obviously the circula 10 molten metal circulating through said conduits and said
vacuum chamber for increasing the temperature thereof.
tion of the molten metal by means of an added gas as
2. An apparatus as de?ned in claim 1, further compris
previously described may also be attained by different
ing means for adding other materials under a vacuum to
means, for example, by centrifugal conveying means of
the molten metal within said vacuum chamber for alloy
the type described in the inventor’s previous United States
ing said molten metal with said added materials by the
Letters Patent No. 2,893,860, or the like.
heat of said metal.
The method according to the present invention has,
3. An apparatus as de?ned in claim 1, wherein said
however, certain other very important advantages. As
evacuating means are constructed and arranged to oper
already stated, the uninterrupted circulation of the molten
ate continuously to withdraw the gases liberated from said
metal forms the secondary circuit of a transformer. This
molten metal within said vacuum chamber.
secondary circuit is closed after the apparatus has been
4. An apparatus as de?ned in claim 1, wherein said
evacuated and the conveying gas has been introduced
conveying means comprise means for injecting a gas into
through pipe 8 and at the very moment when the molten
said inlet conduit adapted to take along the molten metal
metal ?ows over from pipe 6 to pipe 7. After the electric
through said inlet conduit into said vacuum chamber.
current has been switched on to operate the transformer
5. An apparatus as de?ned in claim 1, wherein said
12, 13, this moment may be easily determined by an
stantially closed iron core and a primary induction coil
that the continuous gas extraction process has been
mounted
on said iron core and adapted to be connected
started. The ammeter will also indicate any interfer
to a source of alternating current, said molten metal
ences in the normal operation of the apparatus, for ex
ample, an interruption in the continuous ?ow of metal, 30 circulating in a continuous ?ow from said container
through said inlet conduit, said vacuum chamber and
and the like.
said outlet conduit back to said container serving as a
The strength of the alternating line current which may
6. An apparatus as de?ned in claim 5, wherein said
substantially closed iron core of said transformer extends
35
flow of metal through vacuum chamber 5. The amper
between said two conduits, and means for indicating the
age indicated by ammeter 15 may therefore indicate the
reaction upon the induction current within said primary
volume and velocity of the ?ow and it may also be used
coil for determining the beginning of a continuous process
extent also furnish an indication of the volume of the
for controlling the ?ow, for example, by an adjustment
of the position and elevation of the gas extracting appa
of extracting gases from said molten metal within said
positioning device indicated generally at 16, by an adjust
prising means whereby said reaction upon the primary
induction current is utilized for controlling the operation
vacuum chamber.
ratus relative to the bath of molten metal 2 vertical 40
7. An apparatus as de?ned in claim 6, further com
ment of the amount of conveying gas supplied through
pipe 8, or by an adjustment of the output of the evacuat
ing pump and control valve unit 4’ which is connected
to pipe 4, or by similar means.
of the gas extraction process.
8. An apparatus as de?ned in claim 6, wherein said
control means comprise means for adjusting the elevation
of said vacuum chamber relative to the surface of the
Such adjustments may
also be produced automatically by suitable means known
in the art which operate in response to the indication of
ammeter 15 and the changes in the strength of the pri
mary current.
From the above description, it will be clearly apparent
molten metal within said container.
9. An apparatus as de?ned in claim 6, wherein said
50 control means comprise means for adjusting the opera
tion and output of said evacuating means.
10. An apparatus as de?ned in claim 6, wherein said
that the new method of expelling the gases occluded in
a molten metal, and particularly in steel, is very simple
and highly ef?cient, and requires only a very simple and
relatively inexpensive apparatus.
conveying means comprise means for injecting a gas
into said inlet conduit constructed and arranged to take
55
along the molten metal through said inlet conduit into
Although my invention has been illustrated and de
said, vacuum chamber, said control means comprising
scribed with reference to the preferred embodiments
means for controlling the amount of gas injected into
thereof, I wish to have it understood that it is in no Way
said inlet conduit by said injecting means.
limited to the details of such embodiments, but is capa
ble of numerous modi?cations within the scope of the 60
References Cited in the file of this patent
appended claims.
Having thus fully disclosed my invention, What I claim
UNITED STATES PATENTS
1s:
1. An apparatus for heating up molten metals com
prising a container for holding a molten metal, a vacuum
chamber having an inlet conduit and an outlet conduit
thereon and extending downwardly therefrom, means for
761,920
2,587,793
Schneider _____________ __ June 7, 1904
Waldron _____________ __ Mar. 4, 1952
2,848,317
2,859,262
Coupette et al. _______ __ Aug. 19, 1958
Harders et al. ________ __, Nov. 4, 1958
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