Improvements in Casting Metals.
Year: 1891

page_text: Date of Application, 6th Apr., 1891
Complete Specification Left, 6th Feb., 1892-Accepted, 12th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in Casting Metals.
We WILLIAM SOWERBY of 39, Hereford Road Acton, Middlesex Civil
Engineer, and EDWARD CASPER of 20 Bucklersbury in the City of London
Gentleman, do hereby declare the nature of the invention to be as follows:-
This invention relates to improvements in the casting of metals whereby the
formation of air bubbles and similar defects in castings of all may be prevented,
and the action of oxigen and the imperfections arising therefrom during the cooling
of the metal cast may be avoided and the required degree of homogeneity and
consolidation of the casting is assured.
The mould for the casting is to be constructed as follows:
The outer frame or casing is to be of a shape and size suitable to the casting to
be made, and to be of wrought or cast iron or other air tight materials, securely
hooped or bound if necessary, according to the weight and pressure of the molten
metal it has to contain.
This casing of the mould is to be perforated so as to admit of pipes of suitable
material and dimensions to be placed all round or at an inclination of about 45°
(degrees) downwards towards the inside, the said pipes being of the required
length to correspond with the orifices in the linings of the said casing hereafter
described.
The casing to be lined with fire bricks fire clay or other suitable refractory
material then with a sufficient thickness of moulding sand which is to be coated
with coal dust charcoal or blacklead.
The pipes inserted in the casing are for the purpose of establishing a free passage
for air and gases from the interior to the exterior of the mould.
These pipes or apertures are to be filled with suitable material such steatite
or refractory bricks broken small and carefully screened, and well rammed in.
or they may be filled with asbestos or other uninflamable porous substances, so that
any air or gases escaping from the molten metal may be subjected to the air pump
or other apparatus for withdrawing the same.
The usual moulding pit may be constructed round the mould if necessary.
When the mould is completed then a cover or jacket of either wrought or
cast iron or other suitable metal or material, is to be let down over it by means of
a crane or other mechanical arrangements, so as to completely enclose it, the
bottom being made air tight.
We make in this cover an opening for connecting an exhaust passage referred to
hereafter and for two pipes one of which communicates with an air pump which
being put in motion before the casting, as well as during the time occupied by the
pouring in of the metal and until such metal is partially cooled, keeps the mould
and its casing as nearly as possible free from air.
The pipe is advantageously placed in the upper part of the cover, because the
pouring into the mould of the metal in a molten state expands any air remaining
therein, which therefore rises so that the action of the air pump in withdrawing it
will become more prompt and complete.
The top of the cover is to have an aperture to receive a channel of suitable
material which is to be connected with a hopper furnished with a valve. The
hopper will receive the molten metal, and so soon as it is filled the valve above
referred to is to be opened so that the quantity of metal required may then run
continuously into the mould.
The admission of the metal into the mould may be effected from the sides or
bottom of the mould, but we find it advantageous to pour it into the ton.

page_text: When the filling of the metal into the mould is finished, and the ebullition, if
any, will have ceased-the pumping out of the air is to cease also:-and then cold
dry air is to be admitted into the mould.
For this purpose, the other of the two pipes last mentioned, communicates at one
end with a cooling chamber, and at the other end with the lower part of the
mould.
The refrigerated air to be allowed to pass from the refrigerating chamber into
the mould is obtained in the ordinary manner the same pump which acted as an
exhauster in the first part of the process is now acting as a compressor. The
refrigerated air so admitted escapes from the mould into the open air through an
exhaust passage connected with the upper part of the mould. This cooling process
to be continued until the operation is quite finished and the casting is fit for
removal.
T
1
1001
WILLIAM SOWERBY.
EDWARD CASPER.
COMPLETE SPECIFICATION.
Improvements in Casting Metals.
We WILLIAM SOWERBY of 39 Hereford Road, Acton in the County of
Middlesex, Civil Engineer and EDWARD CASPER of 20 Bucklersbury in the City
of London, Gentleman do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to improvements in the casting of metals whereby the
formation of air and gas bubbles and similar defects in castings of all kinds may be
prevented and the action of oxygen and the imperfections arising therefrom during
the cooling of the metal cast may be avoided and the required homogeneity and
consolidation of castings may be assured.
In carrying our invention into practice we place our mould which is constructed
in the peculiar manner hereinafter described and make our castings within an air
tight pit or chamber suitably connected with air exhausting and compressing
pumps. This enables us to obtain the following advantages.
:―
First We are able to exhaust the mould of air and gases and run the metal
into it so that the casting will be uninjured by the presence of air and gas bubbles
and.
SecondlyWe are enabled to pass into the mould after the casting has taken
place a supply of refrigerated air which will hasten the cooling of the metal and
improve its quality.
Our process is more fully hereinafter described by reference to the accom-
panying drawings which being intended chiefly for purposes of illustration show
merely a simple form of apparatus for carrying out our invention which however is
not confined to such simple form.
Figure 1 is a vertical section of a pit with a mould, therein and the several
fittings required for carrying out our invention.
Figure 2.is a plan of the upper side of Figure 1.
Figure 3 is a vertical section, of the cover as hereinafter described.
Figure 4 is a section of the wall of the mould.
In all the figures the same part is indicated by like reference letters.
The outer frame or casing A of the mould may be of any convenient shape. It
may be of wrought or cast iron or other suitable material securely hooped or
bound if necessary according to the weight or pressure of the molten metal it has
to contain. It should be rather larger than the piece, intended to be cast so as to
allow for the play of the cold air as hereinafter described.
In building the casing of the mould conical templates may be used to form

page_text: perforations or apertures B in the casing all round at an inclination of 75 degrees
or more or less downwards towards the inside, the said conical templates being of
the required length to produce the apertures B through the said casing and the
lining and coating hereinafter described. These templates are removed when the
casing is completed. Any other suitable mode of making similar apertures may be
employed.
The casing may be lined with fire bricks which may be perforated horizontally
and vertically in which case corresponding perforations must be made in the
casing A. No perforations are shown in the accompanying drawings. These
perforations are made in the bricks and casing in order to facilitate the access of
the cold air to the mould and metal. The bricks therefore should be laid so that
the horizontal perforations correspond. We believe these perforated bricks form the
best kind of lining but fire clay or other suitable refractory material can be used
in any of the methods adopted by moulders. Then moulding sand S is to be used
which is to be coated or washed over with coal dust charcoal or black lead as shown
at D. There should be a sufficient thickness of moulding sand to prevent the
metal from flowing through the apertures B as far as the lining C and when there
is a sufficient thickness the suitable porous material hereinafter mentioned need
not be very tightly rammed in the apertures B but may be put in and left
comparatively loose.
The apertures B should be filled with suitable porous, materials such as steatite
or refractory bricks broken small and carefully screened, or with asbestos or other
uninflammable porous substances. These apertures B are so constructed in order
that any air or gases within the mould may be withdrawn by the means hereinafter
described through these apertures whilst the metal within the mould will be unable
to pass through them and also that the cold air may be passed through them as
hereinafter described. The "suitable porous materials are employed to impede
the flow of the metal and so must be rammed in tightly or not according to the
thickness of the sand C and the nature of the metal.
"
When the mould H is completed it is to be placed in a moulding pit or chamber
similar to G in the accompanying drawings built with air tight walls in any known
manner, the moulding pit or chamber is to be covered in by means of an iron or
other suitable cover K. This cover fits in an air tight manner on to the moulding
pit which is thus made into an air tight compartment. This cover K. is to extend
over the mouth of the mould H and is to have the openings and valves hereinafter
mentioned.
In the moulding pit G are openings for two pipes E and L which are perforated
with holes within the air tight moulding pit in order that a communication may be
thus established between the mould and the air pumping and refrigerating
apparatus connected with the said pipes as hereinafter described. The pipe E
advantageously placed in the upper part of the chamber G communicates with an
air pump which being put in motion before the casting as well as during the time
occupied by the pouring in of the metal and until any ebullition in the metal has
ceased keeps the mould and its casing as well as the moulding pit as nearly as
possible free from air. The pipe L is by means of suitable pipes and taps to be
connected with a refrigerating chamber containing a supply of cold air.
On the portion of the cover K that is over the mould is set a cover M of cast
iron or other suitable material extending over the mould H including the casing A.
In the cover M are holes as shown at O (Figure 2) and corresponding holes are
formed in these holes and corresponding holes are intended in conjunction with
the slides F hereinafter described to act as valves for the admission of the molten
metal into the mould.
This cover M which may be bolted or fastened down in any ordinary manner
to K has a mouth so shaped as to receive the crucible or hopper N which is made
of any suitable refractory substance. The cover M which is of considerable
thickness has formed in it the passage J through which the slides F can be run sc
as to open and close the valves O such slides being worked by the levers R or in

page_text: any other well known way. Such slides and valves must be so constructed and
adjusted that in operating them as little air as possible can get into the mould
from outside the pit and allowance must be made for heat expansion in working
:them.
The crucible or hopper N is to be covered with a dome in which there is an
air outlet pipo Z communicating with the air pump. In cases where several
castings are to be made at the same time the cover M must be large enough to
cover all the moulds and the slides F may advantageously be equal in number to
the valves to be worked so that if desired they may be worked in succession and
not simultaneously. Any known device for effecting a communication between the
crucible or hopper N and the interior of the mould which can be opened and closed
at will may be used instead of the said slides and valves care being taken to admit
no air in working. In the crucible or hopper N may be an indicator T consisting
of a flat piece of light refractory material with a rod set in at right angles to it
working through a hole in the top of the crucible or hopper N. The rod must be
so fitted to the hole as to let in as little air as possible but also to work easily.
The indicator T is set in the crucible or hopper N so that when the metal reaches
the desired level the indicator will be raised and the rod forced up so as to draw
attention to the fact that the slides are to be operated.
Any similar device for
indicating the level of the molten metal may be employed.
Into the crucible or hopper N the molten metal is to be conveyed by the conduit
or pipe X controlled by the screw down valve or sliding door Y. As soon as the
hopper or crucible N is partially filled the valves O are to be gradually opened and
left open until the required quantity of metal has been run into the mould or
moulds which has or have been previously exhausted of air as hercinbefore
:described.
Before the metal is conveyed to the crucible or hopper N the latter may be
exhausted of air through the air pump communicating at Z the exhaustion con-
tinuing until the exhaustion of the moulding pit by way of the pipe E ceases; one
air pump being conveniently used for both purposes so that any air or gases
brought by and in the molten metal may be drawn off.
The foregoing arrangement with the indicator T, air outlet pipe Z and the use
of the valves O we believe to be the best method of working our invention when
making castings from a crucible. When however the casting is to be done direct
from the furnace the indicator T and the outlet pipe Z may be dispensed with.
The conduit pipe X made of suitable refractory substance is in that case a closed
tubular conduit connected with both hopper or crucible N and the furnace in an air
tight manner and a similar screw down valve or sliding door to Y is placed at the
juncture of the conduit pipe X and the furnace. Previous to casting the valves O
are opened and the air is exhausted by way of the pipe E from the inould H the
hopper or crucible N and conduit pipe Z. Then the screw down valve or sliding
door being opened at the furnace end of the conduit pipe X the metal will be
permitted to flow from the furnace direct into the mould.
When the necessary quantity of metal has been run into the mould and the
ebullition if any has ceased then the pumping or exhaustion of the air and gases is
to cease and the screw down valve or sliding door controlling the conduit pipe X
being closed cold dry air is to be freely admitted as quickly as possible into the
.mould from the refrigerating chamber through the pipe L. The refrigerated air
so admitted can be allowed to escape by suitable valves such as shown at V. The
refrigerated air being obtained in the usual manner, the same air pump which
exhausted the air from the mould H and from the hopper or crucible 'N can serve
for compressing the air to be refrigerated.
Whenever it is proposed to make a casting for guns, shafts, cylinders, or for any
purpose where it is desirable that the casting should be hollow, a core is to be
inserted of a suitable shape and size and in such a manner as may be best adapted
to give the casting the required form and figure. P represents the core for a simple
hollow cylinder.

page_text: Our process is equally applicable to small castings or ingots and when several
of these are to be made at one time the moulds are to be arranged in such a manner
in an air tight moulding pit as described of a suitable form and size that air may
be withdrawn and the process of moulding casting and refrigerating may be
conducted in a similar manner as for one large casting. The moulds for small
castings may be arranged in suitably perforated boxes and may rest on a raised
open frame or table in the moulding pit so that the under as well as the upper
sides of the moulds may be acted upon by the exhaust air pump and also by the
refrigerated air when admitted into the moulding pit.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:-
1. A new mould for castings constructed and arranged as hereinbefore described
so that it may be exhausted and the metal may be moulded and cooled as and for
the purposes and in the manner hereinbefore described.
2. A new kind of apparatus for casting metals consisting of the combination of
the improved mould and the hopper or crucible constructed and operating as and
for the purposes hereinbefore described.
3. In apparatus for casting metals the combination of the mould the hopper or
crucible and the air-tight moulding pit constructed and operating as and for the
purposes herein before described.
4. In apparatus for casting metals the combination of the mould, the hopper or
crucible, the air-tight moulding pit and air exhausting apparatus constructed and
arranged as and for the purposes herein before described.
5. In apparatus for casting metals the combination of the mould, the hopper or
crucible, the air-tight moulding pit and refrigerating apparatus as and for the
purposes herein before described.
6. In apparatus for casting metals the combination of the mould, the hopper or
crucible, the air-tight moulding pit, the refrigerating apparatus and air exhausting
apparatus as and for the purposes herein before described.
7. In casting metals the new method of cooling the metal after it is cast in the
manner and for the purposes hereinbefore described.
8. In casting metals the use in combination of the two methods exhausting the
air and cooling the metal in the manner and for the purposes hereinbefore
described.
Dated this 6th day of February 1892.
AYRTON & THOMAS,
Agents for the Applicants.