IMPROVEMENTS IN METAL MOULDS FOR CASTING STEEL WHEELS
Year: 1885

page_text: I JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention for "IMPROVEMENTS IN
METAL MOULDS FOR CASTING STEEL WHEELS" which Invention has been com-
municated to me from abroad by William Sellers of the City and County of
Philadelphia in the State of Pennsylvania United States of America and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement that is to say :-
The improvements according to this Invention are adapted to the casting of all
forms of wheels in which the rim is connected with the hub by arms or by a
plate or web that is narrower than the rim but as perhaps their most important
application, I will describe them with reference to the manufacture of wheels for
railways. It is well known that the requirements of railway service demand a
wheel with solid bub, arms and rim, or with a continuous web or plate connecting
the hub with the rim and such wheels have heretofore been made almost exclusively
of cast iron with a chilled tread; the higher speeds and heavier traffic of the
present railway system exact requirements beyond the capabilities of cast iron, and
to meet these requirements, solid cast steel wheels have been made similar in form
to the cast iron wheel, but in all cases these steel wheels have been cast in moulds
formed of fire clay or other refractory material that could be brought to a pasty
condition and shaped upon a pattern and then baked, not only to dry them but
also to impart sufficient rigidity to the mould to retain the fluid metal in the proper
shape until, by cooling, this shape becomes fixed. The thickness and backing for
the mould must be such that the pressure from the shrinkage of the cooling inetal
would crush the mould before it would distort the wheel, but it must be sufficiently
stiff to retain the metal in the proper shape until so far cooled as to be permanent.
The material of these moulds is too porous to admit of pouring the molten metal
directly upon the surface, so that it is requisite to wash the interior with plumbago
or other refractory material to impart a sinooth surface to the mould so as to
produce a similar surface upon the casting, and as the carthy material of which the
imould is composed, as well as the wash upon its surface would give off steam and
gas when the molten metal came in contact with it, ample provision had to be
Price Y

page_text: made for the escape of these as well as of the air contained wivum
for every casting, this mould must be renewed, so that the operation is not only
expensive but tedious and consequently it has been found impossible to make such
wheels at a price that would compete with steel tired wheels having built
up centres
of other material. In the developement of the art of steel castings, it has been
found that this metal with a proper chemical composition can be cast perfectly
solid, having a density, ultimate strength and ductility almost identical with those
of a steel forging, and that these characteristics can be more certainly attained
when the casting is made in a metal mould. As the shrinkage of cast steel is
more than double that of cast iron, and as the fluid or semi-fluid steel has very
little tenacity, a slight resistance from the mould would result in a rupture of the
casting. It is the object of this present Invention to obtain a metal mould which
can be separated to permit a shrinkage of the cast metal and which, when separated,
will evenly support the casting, and to this end the invention consists. In a metal
mould provided with a rim, a supporting frame by which a hub portion of the
mould is supported, and a movable relieving annulus between the rim and the hub
portion; and it further consists in a metal mould provided with a rim and sup-
porting frames, which maintain the hub portion of the mould at the proper distance
from each other, and provided further with a movable annulus which determines
the position of its hub portion radially; and it further consists in a metal mould
provided with supporting frames, a rim interposed between said supporting frames,
an upper movable annulus, and a lower movable annulus, and devices for moving
the upper and the lower annulus towards and from each other simultaneously; and
it further consists in a metal mould provided with an upper and a lower movable
annulus and devices through which one annulus is made to counterbalance the
other; and it further consists in a metal mould provided with a space or spaces
within the rim portion of the mould and above the true rim of the wheel to be
cast therein, which space receives the cast metal to supply the shrinkage in the
rin of the casting as it cools. It is to be understood that by a solid hub I mean
a hub not split or divided radially or otherwise as I contemplate either casting
the hub solid and boring it or casting it with a central core and then
boring it.
In order that the said improvement may be more fully understood, I will now
describe the construction of the mould and the manner of operating the same,
reference being had to the accompanying drawings which form a part of this
Specification, and in which Figure 1 is the plan of a Railway car wheel having a
solid hub and a continuous straight web or plate connecting the hub with the tread.
Figure 2 is a sectional elevation of the mould frame and mould in which such
wheel is cast, and showing also a section of the finished wheel in position therein.
Figure 3 is a plan of the mould frame and mould. Figure 4 is a sectional elevation
of the same, showing the matrix in which the metal is cast. Figure 5 is a side
elevation of the mould frame and mould and Figure 6 is a plan of the lower half
of the frame and a portion of the mould which is supported and operated thereon, &
part of this mould being broken away to show more clearly the mode of supporting
and operating it from the mould fraine. In Figure 2 the mould is shown opened
so as to relieve the casting from resistance during shrinkage after the metal is
poured, and the wheel is shown as it is after being bored, turned and finished
ready for placing upon its axle, to illustrate the clearance required for shrinkage.
In figure 4 the mould is shown closed ready to receive the molten metal, the space
within the rim of the mould beyond that required to contain the finished wheel
indicates the amount of surplus metal provided as a sinking head for supplying the
shrinkage in the rim of the wheel, so that after this sinking head is cut off the
remainder of this rim will be solid. A sinking head is necessary at this place
because the plate between the rim and the hub is so thin that it would chill solid
before the rim had solidified, this chilling between the rim and the hub, would cut
off any supply of metal from the sinking head at the hub, and, unless a supply
from some other source is provided, the rin, when cold, would be hollow, because
'

page_text: it solidifies first upon the exterior which defines the size and the shrinkage in
cooling must be supplied from the fluid metal in the interior until this is exhausted;
such a cavity would of itself weaken the rim, from the absence of metal, but the
metal immediately surrounding the cavity would be weakened, owing to its
irregular form and the absence of pressure in cooling; the certainty that such &
cavity existed would detract from the value of the wheel, but the uncertainty as
to its extent would depreciate the market value still more.
The mould proper is composed of five principal parts, the rim A Figures 2,
4 and 5 which is supported by the lower frame B and in turn supports the upper
frame C so that this rim is interposed between the upper and lower frames, they
are all retained in position laterally by the small flanges aa on the rim A and they
are clamped together vertically by the four binged straps D D D D which are
attached respectively to the lower frame B by pin joints. These straps swing over
projections cast upon the upper frame so that as the straps are pushed on these
projections, the upper and lower frame and the rim A are wedged together; theso
projections also serve as handles by which the mould can be stripped to remove the
wheel after it is cast. The upper frame C is provided with vertical bars or webs
by which the inner rim E is attached to the outer one, and this rim E is of such
diameter as to admit the upper hub portion of the mould F and allow free play
laterally for the same, the portion F is supported vertically only, from the rim E,
by means of the ring plate bb and the bolts & d. The lower hub portion of the
mould G is supported upon the top of a similar rim H in the lower frame and so
as to have free play laterally. The flanges at the upper and lower ends of the hub
portions G and F are circular and bevelled to admit the annular portions J and K
of the mould which, when closed fill up the space between the hub and the rim of
the mould, the upper annulus of the mould J is supported from the upper frame C
at four points by the straps c c c c which extend over cams fortned in the shafts L L
in the frame C as shown by dotted lines in figures 2 and 4 the bottoms of the
openings in which these cams work are at such a distance below the centres of the
shafts that the circular and outer portion of the cams will press on these bottoms
when the annulus J is resting upon the rin A so as to force the annulus against
the rim, and when the shafts are turned so that the straps c c c c ure resting upon
the circular portion of the cams, the annulus J will be raised as shown in Figure 2.
The straps c c c c and the blocks with projecting arins M M upon which they are
supported are securely attached to the annulus J by the bolts e e e e the said
arms M from these blocks projecting through slots in the rim of the frame C for the
purpose hereinafter explained. In order that the shafts L L may be rotated simul-
taneously and conveniently, a crank arm fis keyed upon the end of one, and a
hand lever upon the other and these two are connected by the link g. The lower
annulus K of the mould is supported from the lower frame B at four points by the
levers N N the fulcra of which are pins fixed in the frame, one end of each lever
operates in a groove or slot in a projection cast for the purpose on the under side
of the annulus, and the outer end of each lever is provided with a swinging strut
which fits under the projecting arms from the blocks M M so that the weight of
the lower annulus K, through the intervention of the levers N N serves as a
counter-balanco to the upper annulus J and the two will open and close simul-
taneously as the opening and closing devices, (in this instance the shafts L L and
their cams) are rotated back and forth. The annular portions J and K of the mould
are provided with projecting flanges h h overhanging the hub and rim of the mould
respectively which flanges act as squaring pieces to insure the accurate final closing
of the mould. It is evident that when a wheel is to be cast with the plate which
connects the hub with the rim, entirely on one side of the rim, the hub portion of
the mould on that side may be a part of the frame and the mould would require
only one relieving annulus. These improvements are equally applicable in such
cases, the only modification requisite being that the single annulus must then be
counterbalanced if any counterbalancing is required by a weight substituted for
the omitted annulus. In the centre of the lower hub portion G of the mould a

page_text: block of metal O (figure 4) is provided of suitable thickness to carry off the heat
from the cast metal so rapidly that the metal will chill before it has time to soften
or to penetrate the side of the hub. The vertical position of this block in the mould
determines the length of the lower hub of the wheel casting: The upper bub
- portion of the mould is made of sufficient depth to contain the length of hub
required on the wheel casting and a suitable length in addition for a sinking head.
The process of casting a wheel with the above described mould is as follows:-The
frame is to be placed substantially level, with the block O supported at the proper
height. The upper and lower frames must be clamped upon the rim of the mould
by the four hinged straps E D, and the four swinging struts on the end of the
levers N N must be placed in position under the projecting arms from the
_blocks M M, the annular portions of the mould must then be closed against
the rim and hub portions, by rotating the cam shafts in the upper frame
which will adjust the hub portions of the mould radially, that is to say :-
a position concentric with the rim. The mould and frame thus closed and
clamped is mederately heated before the cast is made with a view to avoid a too
sudden heating from the molten metal, and when arranged as described the metal
is poured in rapidly at the hub, until the mould is full. The fit between the
annular portion of the mould and the rim will ordinarily not be so close as to
prevent the escape of the air above the plate of the wheel, but to insure this escape
with ense, a few small grooves should be filed across these surfaces. After the cast
has been made, the mould is allowed to stand about one and a half minutes, or
until a skin of the casting has set, when the lever handle must be moved so as to
open the annular portions of the mould and allow the necessary room for shrinkage
of the wheel. When these portions of the mould have been removed the metal in
the casting will still be so supported by the lower hub and by the bottom flange
on the rim that the weight of the casting can not distort it. The length of time
during which the annular portions of the mould inust remain closed after the cast
has been made, will vary somewhat with the proportions of the wheel it is only
requisite to keep these portions of the mould closed until a skin is formed strong
enough to prevent the fluid metal in the interior of the casting from bursting it
when they are opened, and it is requisite that they should be opened before they
can present any appreciable resistance to the shrinkage of the metal.
the metal has solidified sufficiently to permit the removal of the casting without
distorting. it, the swinging clamps and struts are thrown off, and the upper rim
with the portions of the mould attached to it are lifted off and the casting can be
lifted out of its place by the hub. The mould may then be reclosed as before and the
operation may be repeated as often as required. After the wheel has been removed
from the mould it preferred to pass it directly to the annealing furnace, and after
it is annealed the sinking heads of the hub and rim are cut off and the wheel is
bored and turned.
As soon as
I have shown and described the rim of the mould, the supporting frame, and
the hub portions, as separate and distinct from each other, because, when so con-
structed, a variety of sizes of both rims and hub portions may be used in the same
supporting frames, the several parts will then be free to expand with the heat of
the casting without one being restrained by the other, and those parts directly
exposed to the molten metal can be replaced when injured, with the least expense,
but it is evident that in many cases, the hub portion and the supporting frame for
each half of the mould may be in one piece, the supporting frame in this case being
simply arms projecting from the hub portion, to perinit free expansion as the mould
becomes heated, their outer ends bevelled to receive and center the rim as shown
in the drawing of the outer edge of the supporting frame; in euch case, the inner
circumference of the annulus and the corresponding part of the hub portion must
be cylindrical in place of conical as the annulus can only be then placed in position
when the mould is open. The cylindrical joint between the annulus and the hub
. portion may be quite free without affording any outlet for the fluid metal because
it chills so rapidly that escape through a narrow aperture is impossible. It is also

page_text: evident that with such sizes or proportions of wheels that would not impart suffi-
cient heat to the mould to make its expansion a serious element of destruction, the
rim, hub portion and supporting frame for each half of the mould may be in one
piece, or the whole rim and the supporting frame and hub portion for one half of
the mould may be in one piece, and the supporting frame and the hub portion for
the other half in another piece, in either of such cases, both the inner and the
outer circumference of the annulus must be cylindrical, so that I do not limit
my invention to a metal mould composed of the several separate and distinct pieces
shown in the Drawings..
I am aware that steel castings have been made in metal moulds and that portions
of such moulds have been made removable to permit the shrinkage of the metal
without obstruction, but in all such cases the removable piece could be taken com-
pletely away from the mould, leaving the mould as a whole, connected and self
supporting; but in casting a wheel in which the rim is connected with the hub
by arms or by a plate or web that is narrower than the rim, to which my improve-
ments are adapted, it is requisite to remove an annular portion of the mould between
the rim and the hub to permit unobstructed'shrinkage of the casting, and this must
necessarily cut off the rim from the hub portion. With a mould having its central
part entirely separated from and unsupported by the outer portions provision must
be made for maintaining the several parts in proper relation to each other, so that,
when closed, the matrix shall be perfect and continuous to prevent the escape of
the fluid metal when poured into it, and this I accomplish by the mould frame
in which the devices for opening and closing the annular portions are placed, as
herein before described, and whether this mould frame is in one piece with the hub
portion or with the rim and the hub portions, or in separate pieces as shown and
described, the annular movable portions must of necessity remain within the mould
or its supporting frame. In all moulds heretofore employed for relieving strains in
castings, portions of the upper half alone have been removable and the cast metal
has been supported over its whole under surface by the nould after the removal of
the relieving portions: no mould has heretofore been employed in which any
portion of the under or lower side of the cast metal could be left entirely without
support immediately after casting; no mould has heretofore been employed in
which any portion of both the upper and lower halves were removable so as to
leave the cast metal unsupported on both sides, when the relieving portions of
the mould have withdrawn their support before the cast metal has contracted
appreciably, no mould has heretofore been employed in which a movable relieving
portion of it must of necessity remain within the mould or its supporting frame,
and no mould has heretofore been employed in which two or more relieving
portions counterbalance each other; all of these features are necessary to success-
fully cast such wheels as I propose to make and all of these features are prominent
in my mould and these characteristics clearly distinguish it from all other relieving
and supporting moulds.
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
First In a metal mould for casting steel wheels, a rim, a supporting frame by
which a hub portion of the mould is supported and a movable relieving annulus
between the rim and the hub portion, substantially as and for the purposes herein-
before set forth.
Second: In a metal mould for casting steel wheels, a rim and supporting frames
which maintain the hub portions of the mould at the proper distance from each
other, in combination with a movable annulus which determines the position of its
bub portion radially substantially as herein before described.
Third-In a metal mould for casting steel wheels, an upper movable annulus
and a lower movable annulus between the rim and the hub portions of the mould
substantially as and for the purposes set forth.

page_text: Fourth In a metal mould for casting steel wheels, an upper and a lower
movable annulus in combination with devices through which one annulus is made
to counterbalance the other substantially as herein before described.
Fifth A metal mould for casting steel wheels the said mould being provided
with space for a sinking head within the rim portion of the mould and above the
true rim of the finished wheel, substantially as herein before described.
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.