Year: 1887

page_text: Date of Application, 26th Apr., 1887
Complete Left, 26th Jan., 1888
Complete Accepted, 23rd Mar., 1888
BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool Civil Engineer
do hereby declare the nature of this invention to be as follows:-
The essential feature of my Invention, is the cooling of the metal from the centre
to the outside, or the reverse of the present system-which latter and present system
has the defect, that as the sides of a mass of metal are the first to be cooled, and solidify,
consequently, the enclosed gases are prevented from escaping and thus tho metal is
more or loss porous.
1 will briefly describe my Invention in its application to projectiles and heavy
ordnance.
Previously to pouring the metal into the mould I place a cooling tube exactly in
the centre thereof and in such a position that the absorption of heat from the mass of
the metal is uniform.
The cooling tube is placed in another of slightly larger diameter, this latter tube
serves for the escape of the cooling fluid, which may be refrigerated air, oil steam
water vapour or water, and applied under pressure.
The cooling fluid is forced through the cooling tube during the period the metal
is being poured into the mould, or immediately after the mould is filled with
metal.
The result of the action is as follows-The metal gradually cools-and solidifies in
the centre around the cooling source, expelling, as each molecule closes upon another,
any occluded or enclosed gases-to the outside surfaces, which are the last to
solidify.
The cooling action is under perfect control, and the action is such, that the molecules
of the metal are brought into intimate contact with each other.
The size of the crystals is more uniforın and the metal is more dense, and is free
from internal strains.

page_text: I may form the mould of plumbago, fireclay silicious or other refractory material,
and place same before it is filled with metal, in a gas or other furnace raising the
temperature thereof and that of the mould to a steel melting heat before pouring into
the mould.
I afterwards cool the metal centrally in the manner, aforesaid, all the occluded or
enclosed gases being forced out of the sides of the projectiles.
I may harden or anneal the projectile in any well known manner.
I apply my Invention to Ingot moulds in a similar manner.
The outer cooling tube or that for the escape of the cooling fluid, I may make of
sheet steel, which may afterwards be drilled out of the metal.
In the application of my Invention for cylinders and for heavy ordnance,
I force the air into the centre of the core, the latter being provided with cooling
tubes or hollow central spaces for the delivery and escape of the cooling fluid.
The outside metal can be maintained at a steel melting heat, by the combustion of
gaseous fuel, in a special cavity combustion chamber, built around the mould, which
may be built up of fireclay or other equally refractory material.
If the guns are cast solid and then drilled turned or rimmered out afterwards, I use
the method described for projectiles.
To increase the rapidity of the exclusion of the enclosed gases, I may rapidly revolve
the mould during the cooling of the metal.
Dated this 25th day of April-1887.

page_text: Improved Method of Casting Steel and other Metals, Especially
Applicable for Casting Projectiles, Heavy Ordnance, and like
Materials.
I BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool Civil Engineer
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:
My Invention relates to an improved method of casting projectiles heavy ordnance
and like materials.
Before referring to the two sheets of drawings that accompany and are intended to
form part of this specification I wish it to be distinctly understood that I do not desire
to be confined to the exact details therein shewn as they may be considerably modified
without departing from the nature of our said Invention.
Referring to sheet 1 of drawings Figures 1 and 2 shew my invention applied to
the casting of projectiles. Figure 1 is a vertical section, figure 2 a
section.
plan in
The mould A is surrounded by a gas combustion flue B supplied with gaseous fuel
from the flue C.
Over the mould I place a cover D resting in a sand luted recess E-in the centre
thereof I place a cooling tubular arrangement, through which I pass a cooling media,
of a liquid vapour or gaseous character. The inner pipe G is the supply pipe; the
cooling media flows to the end thereof, and returns through the annular space between
the two pipes G & H. The supply of the cooling media is regulatable by the valve 1.
The cooling gases, when constituted of air which may be refrigerated I utilise to
support the combustion of the gaseous fuel and provide connecting flues J for this
purpose.
The cooling pipe H I close at one end and form it of the same quality of steel, that
the projectile is formed of.
This steel pipe H, I fix in a central orifice I by means of a screw thread, or I make
it taper ended, so that it can be easily removable. I provide distance pieces or radial
fins by which 1 retain the secondary tube H in position.
I fill up the hollow part left in projectile with a fine steel plug and cap thoroughly
screwed into projectile. Or if I do not desire the cooling pipe H to form part of the
projectile, I surround it with a woody fibre in the form of paper or wood so that this
becomes charred and the projectile can be stripped therefrom or may use siliceous or
other refractory material to form pipe H.
Figures 3, 4 and 5 represent respectively a vertical section and plans in section on
lines CD and E F.
The mould K of the gun or other type of heavy ordnance casting, is preferably
formed of specially arranged circular moulded refractory bricks L, joggled into each

page_text: other at the joints; this refractory mould I may internally line with ordinary
moulding sand, in which are formed the connecting metal runners as shewn in dotted
lines.
The highly refractory lining is kept in position by a series of radiating walls
constructed across the annular cavity M which is the gaseous fuel combustion
chamber.
The gaseous fuel enters into the annular space through the openings N from the gas
Blue O.
The air supply for supporting combustion of gaseous fuel ascends through
openings P which are connected to central cooling tube arrangement which said
cooling arrangement consist of an inner tube R, and an outer one S; the outer one
being preferably constructed of a fine quality of steel, so as to form the bore of the
gun; or the metal of the outer tube might be made sufficiently thick to allow of the
bore being drilled out and rifled.
The central or inner tube R is in the centre of the cooling media tube S. The
cooling gas after ascending or passing through the inner tube returns or descends
through the annular space between the inner and outer tubes and finally escapes
through the flue connections V to openings P where it supports combustion of the
gaseous fuel in the annular chamber M. The heat absorbed from the inside of the
casting assists in maintaining the outer shell of casting at a high temperature so
that the action of cooling and solidification proceeds from the centre and radially
outwards.
In order to maintain the outer tubo S exactly in a concentric position to inner tube R
I provide the inner tube with a series of projecting tins, as shewn in section at T
figures 4 and 5.
During the time the metal is being charged or run into the mould the cooling gas is
forced under high pressure produced by any well known mechanical method into
central cooling tube arrangement.
The supply of gaseous fuel is gradually reduced as soon as the temperature of inner
part of casting as fallen below a temperature of say 900° Fah. or to the temperature of
complete solidification.
The temperature of the cooling gas or media as it leaves the cooling tube arrange-
ment can be ascertained, and this will indicate the rate of progress of cooling, as soon
as the internal temperature of the gun has fallen below the degree mentioned. The
gaseous fuel supply is gradually decreased and the cooling air supply is increased, so
that the cooling of the outer side of casting is accelerated until it also falls to the
temperature of solidification.
The products of combustion escape into the annular flue W leading to Chimney X'.
The arrows indicate the direction of flow of the cooling media and of the products
of combustion.
Referring to sheet 2 of drawings figures 6. 7. 8 and 9 shew my Invention applied
to the casting of Steel Ingots.
Figure 6 is a vertical cross section and
Figure 7 is a vertical section in another direction.
Figure 8 is a plan in section and
Figure 9 is a plan of a rectangular section of moulds.
1 is the side of ingot mould which may be of any geometrical form in plan but I
prefer a circular shape.
In the centre thereof I place the cooling tubular arrangement consisting of two
concentric tubes a small one 2 leading the supply of cooling gas vapour or liquid into
centre of mould and a larger one 3 for leading away the cooling media.
The outer tube 1 may make of the same chemical constitution as the casting itself so
that it may form part thereof or if I do not desire that the outer tube should by
contraction form part of the ingot I encase it with plumbago silica or with wood
paper or with vegetable fibre that will by the heat of the metal be converted into
carbon, so as to allow tho ingot to be stripped when cool.
The cooling gases escape from Ingot by the fluo 4.

page_text: For large ingots I may maintain an elevated temperature around them in order that
the cooling from the centre may be made still more effective.
When use rectangular moulds I make the cooling arrangement of rectangular
shaped tubes corresponding to the shape of the moulds.
I may place the rectangular moulds closely side by side so as to maintain the
temperature of the sides of the moulds at a high degree and confine the cooling to the
centre.
In order to preserve the closed end of the outer cooling tube from the action of the
metal when falling from casting ladle I cover the upper end with a cap of fireclay 5
I do not fill the metal above the level of this cap.
My Invention will enable the molecules of the metal cast in a mould, to gradually
close one on each other from the centre outwards this action simultaneously effecting
the expulsion of the gases to the outside edges of mould.
My arrangement of casting will thus obviate the production of internal piping
cavities and internal stress and the metal when cold will bo sound and close
grained.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same may be performed I will proceed to declare my claims
but before doing so, I wish it to be distinctly understood that as far as relates to
ordnance, I disclaim the use of water for cooling the core in the casting of guns as this
is not new but what 1 do claim as novel is-
First. The arrangement for utilising the outer tube of a central tubular cooling
arrangement, to forin part of the gun, and the use of the cooling gases for supporting
the combustion of the gaseous fuel, and the general arrangement for effecting the
gradual cooling of a gun or other casting substantially as herein shewn and
described.
Second. The method of effecting the internal or central cooling of steel ingots
substantially as herein shewn and described.
Third. The method of effecting the internal cooling of steel projectiles, substantially
as herein shewn and described.
Fourth. The general method of casting steel ingots guns and projectiles substantially
as herein shewn and described.
Dated this 25th day of January 1888.