Improvements in the Production of Composite Castings in Metal.
Year: 1890

page_text: Date of Application, 28th Aug., 1890
Complete Specification Left, 26th May, 1891-Accepted, 27th June, 1891
PROVISIONAL
SPECIFICATION.
Improvements in the Production of Composite Castings in Metal.
I, WILLIAM STEWART MALCOLM Assistant Foundry Manager, Carron Works,
Carron, in the County of Stirling do hereby declare the nature of this invention to
be as follows:-
In making heavy iron castings in which are partially embedded blocks of soft
iron to be used for example in the construction of the magnet frames of large
dynamo electric machines the retention in place of the soft iron blocks has
hitherto been mainly dependent on their supposed partial fusion with the cast
iron and on grooves and ridges formed on their surface and upon which the
mass of molten cast iron is supposed to shrink in cooling. In practice however
it is found that with blocks of considerable size no fusion actually takes place
and shrinkage of the cast iron upon the blocks occurs whilst they are expanded
by heat and is insufficient to rigidly grip them, the blocks being usually loose
and liable to rock or vibrate in the cast iron mass. The object of my invention
is to overcome this defect and ensure that in casting such composite masses the
cast iron will be caused to shrink on to the blocks so as in effect to form a
rigid piece when cooled. To that end I pour the molten metal in the usual
way into the mould into which the ends of the soft iron blocks project, and
after allowing the metal to set or partially solidify but previous to the time of
greatest shrinkage, I remove the casting and place it over a tank or vessel in
which water or other cooling fluid is caused to circulate in contact only with
the soft iron blocks whereby said blocks are prevented from unduly heating and
expanding, and the cast iron as it gradually cools shrinks on and rigidly embraces
the blocks. At the same time I take measures by keeping the cope on the
casting or otherwise to keep the cast iron as long hot as possible. Or in lieu
of removing the castings when set, I may form or place the mould previous to
casting over a trough or tank in which water or other cooling agent is caused
to circulate in contact with the blocks.
The invention is applicable for securing blocks or pieces of any metal in
castings of the same or other metal.
Dated this Twenty-seventh day of August. 1890.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in the Production of Composite Castings in Metal.
1, WILLIAM STEWART MALCOLM, Assistant Foundry Manager, Carron Works
Carron, in the County of Stirling, 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 :-
In making heavy iron castings in which are partially embedded blocks of soft
iron to be used for example in the construction of the magnet frames of large
dynamo electric machines the retention in place of the soft iron blocks has
hitherto been mainly dependent on their supposed partial fusion with the cast
iron and on grooves and ridges formed on their surface and upon which the mass
of molten cast iron is supposed to shrink on cooling.
In practise, however, it is found that with blocks of considerable size, no
fusion actually takes place, and shrinkage of the cast iron upon the blocks

page_text: occurs whilst they are expanded by heat and is insufficient to rigidly grip them,
the blocks being usually loose and liable to rock or vibrate in the cast iron
mass. The object of my invention is to overcome this defect and ensure that
in casting such composite masses the cast iron will be caused to shrink on to
the blocks so as in effect to form a rigid piece when cooled.
In carrying out the invention as represented in the accompanying drawings in
which Figures 1 and 2 are vertical sections at right angles to each other and
Figure 3 is a sectional plan illustrating the production of a composite casting of
part of the magnet frame of a dynamo electric machine, I form or place the
mould box A, containing the mould B for the cast iron portion of the frame
over a water trough or tank C, and I place the soft iron blocks D to rest on
end on the bottom plate F of the trough which is spaced to the proper pitch
whilst the other ends project through between plates A', forming a cover to the
trough and through the sand core E, into the space in the mould whereinto the
molten cast iron run. The tank is loosely packed with slag or cinders before
fitting the cover plates A', which rest on uprights G, into position and whilst
pouring the metal into the mould B, the tank forms a vent for the gases coming off
the core.
After pouring the metal and allowing it to partially solidify, water is
admitted and caused to flow through the tank C, around the blocks, whereby said
blocks are prevented from unduly heating and expanding, and the cast iron as it
gradually cools, shrinks on and rigidly embraces the blocks:
By this process the magnets or blocks can be most accurately cast in to the
required pitch. Instead of forming the mould or casting over the tank, I may pour
the molten metal in the usual way into a mould into which the ends of the soft iron
blocks project, and after allowing the metal to set or partially solidify, but previous
to the time of greatest shrinkage, I remove the casting and place it over a tank or
vessel in which water or other cooling fluid is caused to circulate in contact only
with the soft iron blocks.
The invention is applicable for securing blocks or pieces of any metal in castings
of the same or other metal.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture or production of composite castings in metal, substantially in
the improved manner hereinbefore described.
2. The production of magnet frames of dynamo electric machines and analogous
castings of composite metal by pouring molten cast iron into a mould into which soft
iron blocks project and subjecting these blocks to the cooling action of water or
other liquid substantially as described.
Dated this Twenty-fifth day of May 1891
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.