IMPROVEMENTS IN THE PRODUCTION OF SOUND INGOTS AND CASTINGS OF STEEL AND OTHER METALS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1881

page_text: LETTERS PATENT to Alfred Longsdon, of New Broad Street, in the City of
London, for an Invention of "IMPROVEMENTS IN THE PRODUCTION OF SOUND
INGOTS AND CASTINGS OF STEEL AND OTHER METALS, AND IN APPARATUS
CONNECTED THEREWITH." A communication from abroad by Frederic Alfred
Krupp, of Essen. in the Empire of Germany
PROVISIONAL SPECIFICATION left by the said Alfred Longsdon at the
Office of the Commissioners of Patents on the 30th June 1881.
ALFRED LONGSDON, of New Broad Street, in the City of London. "IMPROVE-
MENTS IN THE PRODUCTION OF SOUND INGOTS AND CASTINGS OF STEEL AND
OTHER METALS, AND IN APPARATUS CONNECTED THEREWITH." (A communication
from abroad by Frederic Alfred Krupp, of Essen, in the Empire of Germany.)
According to this Invention the mould for the ingot or other casting is so
constructed that it, when closed, can withstand a very considerable internal
pressure. Immediately after the steel or other metal has been poured into the
mould, communication is made between the interior of the mould and a vessel
containing a liquid or solid substance of such a nature as to be in the gascous state
under ordinary atmospheric pressure and temperature; carbonic acid may be
employed for this purpose.
According to the temperature to which the vessel or the substance therein is
exposed, and according to the properties of the substance employed, a gas pressure
of any required strength may be thus obtained in the mould or on the surface of
the metal therein, and pressure is maintained in the mould until there is no further
tendency to the formation of hollow spaces or pores in the ingot or casting.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alfred Longsdon in the Great Seal Patent Office on the
30th December 1881.
'
ALFRED LONGSDON, of New Broad Street, in the City of London. " IMPROVE-
MENTS IN THE PRODUCTION OF SOUND INGOTS AND CASTINGS OF STEEL AND
OTHER METALS, AND IN APPARATUS CONNECTED THEREWITH." (A communication
from abroad by Frederic Alfred Krupp, of Essen, in the Empire of Germany.)
According to this Invention sound ingots and castings of steel and other metals,
such as iron and copper, and alloys, such as bronze, are produced by properly
applying the pressure of gas on the molten metal in moulds, which are constructed
so as when closed to be able to withstand a very considerable internal pressure,
and all in the manner hereinafter described.
After the steel or other metal has been poured into the mould the latter is
tightly closed, and immediate communication is then made between the space
above the molten metal in the interior of the mould and a vessel or reservoir
which contains a substance in liquid or solid form, such as carbonic acid, which
under ordinary pressure and temperature is in the gaseous state, and which can be
placed or maintained under great pressure as required.
According to the temperature to which the reservoir or the substance therein is
exposed, and according to the properties of the substance employed, a gas pressure
of any required strength may be thus applied to the molten metal in the mould.
As the applied pressure must be regulated within limits decided upon as desired,
the above mentioned reservoir is placed in a bath of water, oil, or other suitable
fluid, which by the admission of steam or water thereto can be heated or cooled as
required. At the ordinary temperature of the atmosphere, say at 60° F., the
pressure obtained by the liquefied carbonic acid is about 52 atmospheres, at 86°
about 74 atmospheres, and at 212° F. the pressure is found to rise to about 400
atmospheres, and at 400° F. even to 800 atmospheres. Where a satisfactory result
is found on examination of the ingot to have been obtained by the lower pressures,
it is obvious that the higher pressures should not be resorted to.
The amounts of the pressures depend upon and are influenced according to the
extent to which the reservoir is filled, and the temperatures when they are higher
than 30° C. or 80° F., termed the critical point.
For the purpose of enabling the pressure to be most advantageously applied, the
upper part of the molten metal is kept hot as long as possible, while the ingot is
gradually and evenly cooling and contracting by providing the upper part of the
mould with an interior lining of refractory material. An equivalent or additional
means for the same important object or end consists in pouring in a layer of molten
slag on to the surface of the molten metal immediately after it has been poured
into the mould, and before closing the mould and admitting the gas pressure into
same.
Another equivalent or additional method of effecting the like object (but one
less advantageous) may be used, and consists in making use of a thick cover of a
refractory material, which is a bad conductor of heat. This cover is dropped on
to the top of the molten metal or slag.
The pressure is maintained on the metal in the mould until there is no further
tendency to the formation of hollow spaces or pores in the ingot or casting.
It has been in some cases proposed to use linings of refractory material, which
practically surround the molten metal in the mould, but the action of such material
at the lower part would be disadvantageous and defeat the object of this Invention,
which is to provide for the pressure being applied properly; and to enable this to

page_text: be done the molten metal is kept as hot as possible at the upper part of the ingot
or mould, while the lower part is cooled or allowed to grow cool.
Figure 1 of the accompanying Drawings is an elevation in part section of a
mould and a gas reservoir constructed for the purpose of this Invention, and
arranged for the mould to be charged with the molten metal from above.
Figure 2 is an elevation in part section of a mould and a gas reservoir, where
the mould is charged from below.
Figure 3 is an end elevation of part of Figure 2, that is, of the conduit for
conveying the molten metal into the mould.
Figure 4 is a vertical section through mould to be charged from above.
Figures 5 and 6 are sectional views illustrating two forms of mould covers.
Figures 7 and 8 are sectional views showing two other forms of mould covers
and modes of forming joint with the mould.
Figures 9 and 10 are sectional views showing other forms of mould covers and
modes of forming joint with the mould.
Figure 11 is a sectional view of a modified form of mould.
Referring to Figure 1, A is a very strong metallic reservoir or flask made, say,
of wrought iron welded and containing the carbonic acid or other substance which
is to supply the required very high gas pressure to the molten metal in the mould.
The flask A is placed in a bath P of water, oil, or other suitable fluid.
M is a pipe
for conveying steam into the fluid for the purpose of heating it, and N a pipe for
conveying water into the fluid for the purpose of moderating the heat of the fluid.
By means of the valves m and n on these pipes M and N respectively, the regulation
of the heat of the fluid in the bath P is effected as required, and thereby again the
heat and pressure of the substance contained in the flask A. C is a valve for closing
or opening the flask A as required. By means of valves and pipes the flask A may
of course be put in communication with any desired number of moulds.
D is the mould here shown of a form suitable for casting ingots, but it may be
made of any desired form to suit the casting required to be produced. A pipe B
forms communication between the flask A and the upper part of the mould; the
valve C serves to regulate the admission of the carbonic acid gas or other substance
from the flask A to the mould D. The latter may, as here shown, be formed with
a refractory lining I which forms a bad conductor of heat for the purpose (as
already stated in the preamble to this Specification) of keeping the upper part of
the metal in a molten state as long as possible so as to allow it to cool and contract
evenly and slowly. The line x, x, indicates the level to which the metal should be
charged into the mould.
W is a loose cover of refractory material which is dropped on to the surface
of the molten metal or slag for the purpose of keeping the part hot as long as
possible while the ingot cools down.
D¹, D¹, are wrought irou hoops shrunk on the outside of the mould to strengthen
it. E is a strong cover. F, F, are bolts whereby it is secured to the mould D,
and ff, are cotters passed through them. K. is a turned ring of steel or copper of
the section shown, and serving to make a gas tight joint for high pressure; it acts
on the same principle as the so called cup leathers in hydraulic presses, inasmuch
as the gas pressure in the mould tends to force the two lips of the ring K apart,
and therefore one lip against the bottom of the turned or faced part of the cover,
and the other lip in the other direction, that is, against the bottom of the recess in
which the ring K is placed. The higher the pressure the tighter the ring will
make joint.
The joint between the mould D and its cover E may be made with plumbago,
or with asbestos, mill-board, or in other suitable well known manner for high
heat and high pressure instead of with the ring K shown here.
L is a pressure gauge. V is a disc of refractory material placed in the bottom of
the mould to protect this part against the direct melting or cracking influence of
the stream of molten metal.
The mode of casting with this apparatus is as follows:-When the cover E has

page_text: been removed (for which purpose it is provided with eyebolts e to lift it by) or
turned to one side after all the bolts F except one have been removed, the molten
metal is poured in. When it has reached to about the level x, x, a layer of molten
slag is poured in on the top of it for the reason stated. The lid W is then dropped
on to the top of the slag and the joint ring K is then placed into its recess, and the
cover E quickly put on and fastened down securely and tightly; the cock C is
then opened admitting gas pressure on to the top of the slag and molten metal in
the mould, and this gas pressure is maintained until the ingot has cooled down to a
dull red heat, whereupon the valve C is closed and the cover E then removed so
that the ingot may be taken out. If the bottom of the mould were not protected
by the disc V, the hot stream of metal impinging directly on it would melt this
part and form a recess therein, or crack it. The gas pressure is indicated by the
gauge L, and can, as stated, be conveniently regulated to any required extent by
means of the steam valve m and water valve n.
In Figures 2 and 3 is illustrated the mode of casting from below. The metal is
run into the mould from the conduit G. G¹ is a nut formed in a cross head, which
by means of two rods is so connected to the bed plate S that it can be swung out
of the way of the conduit inlet funnel when the inetal is to be poured in by the
said inlet funnel; G2 is a screw working in the nut G¹, and furnished with a
crutch handle, so that the screw can be forced down upon the cone plug T to close
the inlet funnel securely against the high internal gas pressure. Other suitable
means may be used for this purpose, some of which will be described further on
with reference to moulds to be charged from the top.
U is a valve or cap to allow the air to escape during casting, but which is closed
before admitting the carbonic acid gas.
The joint between the mould and the bottom may be secured by asbestos, mill-
board, or other suitable material, or by an expanding metallic ring.
Figure 4 shows a mould with a cover E which is fastened down before pouring
the metal in, and it is therefore provided with an inlet funnel through the cover
similar to that shown at the conduit G, Figures 2 and 3, that is, with a cone plug T
wbich can be similarly fastened down in its seat by means of screw and nut as
described. To charge this mould, take the cone plug out, open the air valve U,
run the metal in, then the slag on the top of it, put in the plug, close the cap or
valve U again, and let the gas pressure in as before. In Figure 5 the cover inlet
funnel is closed by means of a screw cap G*.
Figure 6 shows a cover inlet funnel with a cap G* provided with projections g
which take under lugs on the neck in such manner that the cap G* by a partial
turn is locked or unlocked as required in a similar manner to a bayonet joint.
Figures 7, 8, and 9, show two kinds of cover joints, rings K, viz., in Figure 7 a
copper or other ring which, originally of a round section, is forced into a square
cornered groove formed in the cover and on the top of the mould, and in Figures S
and 9 a double flanged steel or copper ring, such as shown at Figure 1, but placed
differently, the mode of action however being the same as described with reference
to Figure 1.
Figure 10 shows on one side one form of cover joint, in which an angle shaped
thin metallic ring is used for making a joint, and on the other side another form
of cover in which the joint is made by means of a T shaped thin metallic ring, the
internal pressure in both cases, as above described, tending to force the thin edges
of the rings against the mould and its cover.
Figure 11 shows a mould closed at the top, except in one place, where it has a
hole suitable for pouring in the molten metal and then the molten slag; the hole
is then closed by means of a small cover E and cottered bolts F, a metallic joint
ring K having first been placed in the recess formed for it.
And having thus described and ascertained the nature of this Invention, and the
modes in which the same may be carried into effect, I declare that I claim,-
First. The method of producing sound or non-porous metallic ingots or castings
by pouring the molten metal or alloy into a mould, such as is herein described, and

page_text: admitting high gas pressure into the mould when closed and maintaining it therein,
until there is no more tendency to the formation of pores, substantially as set
forth and shown in the annexed Drawings.
Second. The method of producing sound or non-porous metallic ingots by pouring
the molten metal or alloy into the mould, closing the mould and admitting high
gas pressure into the mould, combined with the use of means such as are herein-
before mentioned for keeping the metal hot at the upper part of the mould, the
pressure being maintained until there is no more tendency to the formation of
pores, substantially as set forth.
Third. The use of a mould, such as D, constructed to withstand and retain very
high fluid pressure and heat in combination with a reservoir, such as A, constructed
to withstand a very high fluid pressure, and placed in a bath containing liquid, the
temperature of which can be regulated as required, all substantially as described
with reference to the accompanying Drawings and for the purpose set forth.
In witness whereof, I, the said Alfred Longsdon, have hereunto set my hand
and seal, this Twenty seventh day of December, in the year of our Lord One
thousand eight hundred and eighty one.
ALFRED LONGSDON. (L.S.)