Improvements in Producing Metal or other Castings
Year: 1892

page_text: Date of Application, 13th Apr., 1892
Complete Specification Left, 13th Feb., 1893-Accepted, 13th May. 1893
PROVISIONAL SPECIFICATION.
Improvements in Producing Metal or other Castings
We JOHN FREDERICK DUKE of 141 Great Suffolk Street, Southwark in the
County of London, Engineer, and FREDERICK REDMAN of 20 High Holborn in
the County of London, Manufacturer, do hereby declare the nature of this invention
to be as follows:-
This invention has reference primarily to the production of castings in bronze or
other metal and particularly of castings of a more or less intricate or complicated
nature and its object is to obtain these castings seamless, that is to say, without the
seams or lines which are unavoidably produced when the moulds are made in
sections.
According to our invention we take the pattern which is to be reproduced as a
casting and we coat it with india rubber, either pure or mixed with sulphur for
subsequent vulcanization. This coating or covering of indiarubber may be
advantageously obtained by dipping the pattern in the rubber while this is in a
semi-liquid or viscous state. When the rubber has set and either before or after
vulcanization (if it is to be vulcanized), we make a plaster cast of the pattern with
its rubber covering. We next open this plaster cast, remove the original pattern
with its rubber covering and reproduce the plaster in metal to form a mould box.
We then slit the rubber covering in the least conspicuous place and detach it from
the pattern. We then place this rubber covering in the mould box, the covering
forming a facing or lining to the mould and we pour into it a very fusible alloy
such for example as a bismuth alloy so as to form a casting of the same.
casting when set and the rubber has been removed, constitutes a seamless pattern
of the object to be reproduced. Next, this fusible casting or pattern is embedded
in kaolin or other suitable material tightly rammed or pressed in a flask or mould
box which is then warmed to melt the fusible alloy. This when melted is run out
by the gate or gates, and bronze or other metal or alloy is then poured in in the
usual manner to form the final casting which is thus produced without seam.
This
Our invention is also applicable to the production of seamless castings in plaster
of paris or like material. In this case we follow the process or method above
described up to the point where the rubber covering is placed in the mould box.
Then instead of pouring in a fusible alloy we pour in the plaster of paris, which
when set and the rubber has been removed constitutes a seamless finished casting.
Dated this 13th day of April 1892.
J. C. MEWBURN,
55 and 56, Chancery Lane, London, Chartered Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Producing Metal or other Castings.
We JOHN FREDERICK DUKE of 141 Great Suffolk Street, Southwark in the
County of London, Engineer, and FREDERICK REDMAN of 20 High Holborn in
the County of London Manufacturer, 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 has reference primarily to the production of castings in metal or
metallic alloy such for example as bronze and particularly of castings of a more
or less intricate or complicated nature, and its object is to obtain these castings

page_text: with a well finished even surface free from the seams which are unavoidably
produced when the moulds are made in sections.
According to our invention we take the object or pattern which is to be
reproduced as a casting and we coat or cover it with india rubber, either pure o
mixed with sulphur for subsequent vulcanization. This coating or covering o
india rubber may be advantageously obtained by dipping the pattern or object
once or oftener in the rubber while this is in a semi-liquid or viscous state, and
allowing the rubber to set. Then, either before or after vulcanization, we give the
rubber a backing to enable it to be used as a mould as hereinafter described after
it has been removed from the object or pattern which has been covered thereby
A convenient way of giving this rubber a backing is to make a plaster cast of the
pattern with its rubber covering; then to open this plaster cast, remove the
original pattern with its rubber covering and reproduce the plaster cast in metal to
form a mould box; next to slit or open the rubber covering in the least conspicuous
place which will allow it to be easily stripped off, and to detach it from the pattern;
then to place this rubber covering in the mould box, the covering forming a facing
or lining to the mould, or more correctly speaking the mould forms a backing to
the rubber.
Into the backed rubber mould or rubber faced mould we pour a fusible alloy
such for example as a bismuth alloy, or in some cases a wax, such as paraffin or
beeswax, so as to form a casting of the same. This casting when it has set and the
rubber has been removed, constitutes a seamless pattern of the object to be
reproduced. Next this fusible casting or pattern is embedded or packed in dry
kaolin alone or mixed with a suitable material. We find a mixture of kaolin and
bone ash or other like phosphate answers well in the proportions of about 90 parts
of kaolin to 10 parts of bone ash or phosphate. The kaolin is tightly rammed or
pressed in a flask or mould box which is then warmed to melt the fusible alloy or
wax. This when melted is run out by the gate or gates, and bronze or other alloy
or metal is then poured into the mould (which for some metals or alloys is heated)
to form the final casting which is thus produced without seam and of a well-finished
even surface. In cases where the casting is required to be hollow and a core has
therefore to be used in producing the same we make an india rubber bag having
the shape or configuration of the hollow and produced in a similar way to that
above described for producing the rubber mould and we fill it with sand or other
such substance to prevent it collapsing. We insert this india rubber internal mould
or core into the rubber mould before pouring in the fusible alloy, and when the
fusible casting has been produced between the outer india rubber mould and the
interual mould or core we empty out the sand and withdraw the india rubber bag.
Then when we embed or pack the fusible casting or pattern with the kaolin o
other substance we pack the inner mould or core as well as the outer mould.
Our invention is also applicable to the production of seamless castings in plaster
of paris, clay, wax or like materials. In this case we take the rubber mould and
instead of pouring in a fusible alloy we pour or press in the plaster of paris or other
material which, when it has set and the rubber has been removed, constitutes a
seamless finished casting. When a casting in wax has been thus produced it can
be employed as a pattern in the production of castings in metal or metallic alloy in
any known manner.
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. In the production of metal castings, the use of an india rubber mould, or of a
mould faced with india rubber, to obtain a seamless pattern in a fusible alloy, wax
or other suitable material, substantially as and for the purpose hereinbefore
described.
2. In the production of metal castings, the use of a pattern in a fusible alloy,
substanzially in the manner herembefore de-cibed.

page_text: 3. In the production of metal castings, the process which consists in first making
in a fusible alloy a pattern of the object to be reproduced, in then embedding this
pattern in dry kaolin or kaolin and bone ash or other phosphate well rammed round
the pattern, then melting and running out the fusible pattern, and lastly pouring
the metallic alloy or metal which is to form the final casting into the kaolin or
kaolin and phosphate, substantially as herein before described.
4. In the production of metal castings, the process which consists in coating or
covering the object to be reproduced with india rubber, then backing up the india
rubber so that (having been removed from the object) it will constitute a mould
which is the exact counterpart of the object, then taking a pattern or casting from
this mould in a fusible alloy, then embedding this pattern in kaolin or other suitable
material, then melting and running out the fusible alloy, and lastly pouring the
metallic alloy or metal which is to form the final casting into the kaolin or other
material, all substantially as hereinbefore described.
5. The production of well finished seamless castings in plaster of paris, clay or
wax, by the use of an india rubber mould or a mould faced with india rubber,
substantially as herein before described.
6. The manufacture of metal or other castings in the manner hereinbefore
described.
Dated this 13th day of February 1893.
J. C. MEWBURN,
55 and 56, Chancery Lane, London, Chartered Patent Agent.