Improvements in or relating to Cores for Casting.
Year: 1897

page_text: Date of Application, 2nd Mar., 1897-Accepted, 17th Apr., 1897
CUMIDELE DI DUIFICATION.
Improvements in or relating to Cores for Casting.
I, MORDECAI HIATT FLETCHER, Dental Surgeon, of Eden Avenue Avon-
dale, Cincinnati, Ohio, United States of America, 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 cores for casting hollow articles such as water and gas-
mains, etc. in which a core-bar is employed as a basis on which is built up an
ultimate layer of "loam" presenting a surface against and around which the molten
metal is run, in the mold. In these cores it is necessary to provide for the shrinkage
of the casting in cooling, and also for the withdrawal of the core-bar-for new opera-
tions, after the casting has "set."
The practice almost universally pursued is, first, to wind upon the bar in adjacent
convolutions a rope or band of hay or straw; next to fill the interstices and cover
the general surface of the hay rope with a layer of plastic clay, which is then kiln-
dried; and lastly to surface with a layer of loam which is then also kiln-dried.
Cores thus made are open to objections which, it is the object of my invention to
remedy. Among these are the following ;-
First, the character of the hay or straw rope-layer requires the use of plastic clay,
which forced into the interstices and between the coils and often seats against the
bar itself. The clay-layer is intended to be hardened under heat, and produces an
"arch" of sufficient strength to sustain the pressure of the molten metal until it
"sets," as against the elasticity of the rope-layer, yet permit the shrinkage of the
casting and the withdrawal of the core-bar by the destruction of the rope-layer
under heat of the casting. These objects are frequently defeated by the seating and
hardening of the clay against the core-bar in places, producing enlargements or
corrugations, strains, breakages, or other imperfections in the casting, or binding
the core-bar, so as to make its removal extremely difficult and troublesome.
Secondly, the cost of the hay-rope and clay, and the time and expense of
manipulation in producing the core as described, and the removal of the core-bar
from the casting, added to the percentage of loss and injury to castings and core-
bars, besides delays and impediments in manufacture constitute considerable items
of expense to be avoided if possible.
My improvement consists, first, in an improved combustible foundation for the
Joam-layer wherein the use of the clay is entirely dispensed with and a com-
paratively inexpensive material substituted for the rope-layer; which improved:
layer is uniformly concentric with the bar, comparatively thin and non-elastic; also
destructible by heat, yet so slowly as to allow the setting of the casting and its
shrinkage without impediment or injury, and allows the free withdrawal of the
core-bar.
It consists also in a core complete, produced in the manner herein described. -
My invention is illustrated in the accompanying drawings, in which ;—
Figs. 1 and 2 are vertical and cross-sections, respectively, of a core made
according to my invention, shown in the flask ready for casting.
Figure 3 is an end-elevation ;
Figure 4 a top-plan view of an apparatus designed for producing the core
according to my invention.
Fig. 5 is a detail of the movable connection for rotating the core-bar, and.‹

page_text: Fig. 6 is a diagrammatic view, illustrating the operation of forming the com-
bustible layer on the core-bar.
In carrying out my invention I first prepare a quantity of combustible matter,
such as wood, leaves, stubble or other refuse or cheap material, in a finely com-
minuted state (such, for example, as "saw-dust,") and add thereto a fluid cementing
agent, (such, for example, as fluid "starch-paste") and mix same into a plastic con-
sistency. I find in practice that fifty pounds of water and one of common starch,
brought to a " boil
to hydrate the starch, is a good working proportion for common
wood saw-dust, and allows a sufficient quantity of water to saturate the wood, and
with it to form as before stated, a somewhat plastic mass, of the consistency of thin
mortar.
This material, thus prepared, is applied directly to the surface of the bar A,
which is usually a hollow metal tube with perforated wall; and, by compression to
drive out the excess of starch-liquid, is formed into a concentric layer a¹, of uniform
thickness.
This is rendered firm and rigid by drying out the moisture, causing the particles
to adhere to each other and the layer to the bar, and constitutes a foundation on
which is placed a concentric outer or finishing layer a³, of loam, which constitutes
the casting surface. (See Figures 1 and 2.)
There is thus interposed between the core-bar surface and the layer of loam
which is more or less friable under heat, a thin, perfectly uniform and rigid layer
of combustible material, unyielding to centripetal pressure, yet slowly destructible
by the heat of the casting whereby by the time the casting shrinks, a practically
empty space surrounds the core-bar beneath the outer loam-layer, admitting the
fullest shrinkage of the casting without strain, and also permitting the withdrawal
of the core-bar without impediment. These conditions also insure a true contour
for the casting, free from the swells or corrugations caused by the elasticity of a
rope-payer or its too rapid combustion, or by the rings of-clay formed between the
rope convolutions seated against the core-bar and hardened by heat.
To produce the combustible layer cheaply and expeditiously, I have devised and
employ the following described apparatus, shown in Figures 3 to 6 inclusive, upon
the drawings.
Upon a suitable framework or support B, are journalled two rolls 6' 6², spaced
apart sufficiently to receive between them the core-bar A which rests in socket
pieces S S adjustable toward or from the roll 62, to regulate the thickness
of the layer to be formed. Each of the socket-pieces S carries, upon a stud c,
projecting outwardly below the bar A, a movable bracket d, having a stud
projecting inwardly in the prolonged axis of the bar A; upon the latter stud is
centered a spur gear d', having a projecting hub d2 adapted to fit within the bar A,
with a feather d³, entering a corresponding end-slot of the bar A, to rotate the
same.
A corresponding spur gear e, on one of the projected journals of the roller b',
meshes with the gear d', to produce equal rotative speed, communicated from any
source of power, as for example, a crank c¹. At the opposite end of the bar A, the
arm d, carries a spur-gear f1, meshing with a corresponding gear upon the projected
journal of the roller 2 whereby the motion is transmitted equally to the roller 6*.
The arms d, are arranged as described, so as to be withdrawn at will, releasing the
intermeshing gears. When so withdrawn to the end of their supporting studs c,
they may be dropped down as indicated by dotted lines in Figure 5, to clear the
core-bar A, and permit its removal from, or replacing a new one in, the socket
pieces S.
Beneath the core-bar so mounted, is carried a web W, of "wire-cloth" or
equivalent structural fabric, one end of which is fastened to the roller b', and the
other to the frame B, being first carried over the roll 62, and suspending in a lower
bight, a weighted bar or roller b³, all as shown in Figures 4 and 6.
Above the roller b, is placed a feed shelf C, from which the material herein-
before described is fed to the web as it passes down between the roll 63, and the

page_text: core bar A, being distributed by hand in any convenient manner, as by an
elongated strip or "scraper" easily manipulated.
A trough, D, Fig. 6, is placed below the rolls to catch the liquid squeezed from
the material of the layer as it is formed and compressed upon the core-bar by the
action of the web W and the roll 2; and to assist this action and remove the
adhering starch-liquid from the exterior of the web W, a permanent scraper g,
arranged in connection with the trough, having a rubber "lip" bearing upward
against the web, at the lower side of the core-bar.
IS
The operation already indicated, may be summarised as follows: -The material
being suitably distributed, and placed to enter between the roll 2, and core-bar A,
at the upper diverging angle of surfaces, and upon the web W, the power is applied
to rotate the rolls in the directions indicated by arrows in Figure 6. The material
passing between the roll 62, and the core-bar A, is distributed and compressed upon
the core-bar and held in place by the web W, which passes beneath the core-bar,
moving with the same velocity. The excess of liquid squeezed out by the com-
pressive action of the rolls and the web, is caught in the trough below, and again
utilized.
The layer being thus applied, is fixed and hardened by removing the core-bar to
a drying oven; and when so dried, the loam layer is applied, dressed and dried in
the usual manner, completing the core.
The material used for the layer may be varied according to local conditions.
Comminuted leaves, twigs, shrubs, grasses, weeds, stubble, straw, bark of trees, etc.
may be employed, for the purpose, or any other woody or vegetable matter, capable,
when treated and applied as described, of producing a layer destructible by charring
or actual combustion, yet of sufficient firmness and rigidity to constitute a foundation
for the loam-layer; but the most satisfactory results have been obtained by the use
of "saw-dust." Quite a range of cements may be also employed; the essential
quality being that, having the proper cementing quality at the beginning, it shall
lose its cementing quality by the heat imparted through the intervening material
by the casting.
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. An improved core for casting hollow articles of metal, consisting of a metal
"core-bar"having applied thereto a concentric combustible layer of finely divided
woody matter or vegetable fibre held together by a cement that loses its cementing
quality when highly heated and upon this a second or finishing layer of loam or
other material to form the casting surface substantially as described.
2. A destructible foundation for the loam or equivalent surface of a core con-
sisting of comminuted woody fibre or similar material, moistened with starch paste
or similar cement, and applied. to and dried on a core-bar as an independent layer
substantially as described. -
3. An apparatus for applying a combustible layer to core-bars embodying two
opposite rolls provided with means for their rotation as desired an intervening
carriage for the core-bar, rotated correspondingly with the rolls, and a web of wire-
cloth or equivalent material carried by or upon the outer rolls and beneath the
core-bar substantially as described.
4. In an apparatus of the character indicated, in combination with the outer rolls
and their gears, the intervening socket-bearings for the core-bar, and the movable
arms carrying the gears, provided with means for engaging and rotating the core-
bar, substantially as described.
5. In an apparatus of the character indicated, the combination of the outer rolls
and intervening core-bar, the web attached at one end to the roll passing thence
beneath the core-bar and over the opposite roll to a fastening upon the frame, and
the rolling weight suspended in a lower bight of the web between the last roll and
the frame, substantially as described.

page_text: 6. The combination and arrangement of parts constituting the complete machine
substantially as and for the purpose described and illustrated in Figures 3, 4, 5
and 6 of the accompanying drawings.
BOULT & WADE,
Agents for the Applicant.