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Патент USA US2405254

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> Aug. 6, 1946.
R. K. HOPKINS
. 2,405,254
MOLD CORE
Filed Marqh '2, 1943
13”?
12-06114“ _ "
INVENTOR ,
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BY Wk.
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ATTORNEY
Patented Aug. 6, 1946’
2,405,254
UNITED STATES PATENT OFFICE
2,405,254
MOLD CORE
’
Robert KHopkins, New York, N. Y., assignor to
The M. W. Kellogg Company,
New York, N. Y_.,
a corporation of Delaware
1
Application March 2, 1943, SerialyNo. 477,738
4 Claims. (01. 22_17c)
The present invention relates to molds, and
more particularly to cores for shaping the inte
rior of hollow castings.
In casting hollow objects the use of a metal
core is often desirable, particularly because of its
durability. However, shrinkage of the cast metal
makes removal of the core diiiicult, and will usu
ally produce su?icient strain in said core to per
manently deform it and render it unserviceable
for further use.
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2
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tively. The angle betwe n these inclined wedge
surfaces l1 and the coe?cient of friction between
the contacting surfaces of the wedges I2 and the
segments H are such that upon application of
radially inward pressure on the segments H re
sulting from shrink pressure the wedges l2 slip
radially inwardly along the inner surfaces [4 of
said segments. This radially inward sliding of
the wedges l2 causes collapsible approachment
10 of the segments H, and resultant reduction in the
One object of the present invention is to pro
vide a new and improved metal core which can
diameter of the core I 0.
-
The core sections I I and I2 are normally main
be easily removed from a casting, and which will
tained in expanded position shown in Fig. 2 by,
not be permanently upset or deformed by the
resilient means comprising radially extending coil
shrinkage pressure of the casting thereon.
15 springs 29, retained at their inner ends in respec
As a feature of the present invention, the core
tive recesses 2| of a block 22 which is set in the
is of sectional construction and is collapsible into
interior of the core l0, and which may be of metal
a smaller cross-section upon application of
as shown or of suitable refractory material. The
shrinkage pressure thereon.
outer
ends of these coil springs 20 bear against
As a further feature, the sections of the core 20
the bases it of the wedges [2 to urge these wedges
are automatically restored to expanded condition
radially outwardly. Three of these springs 28
when the shrinkage pressure is removed.
are arranged in the upper part of the core Hi and
As another feature, the different sections of the
three in the lower part.
core are hollowed to permit circulation of a cool
The internal hollow defined conjointly by the
ing liquid therethrough.
Various other objects, features and advantages
of the invention will be apparent from the fol
lowing particular description, and from an in
spection of the accompanying drawing, in which
core sections H and I2, has an equilateral hex
agonal cross-section, and the block 22 has a
smaller equilateral hexagonal cross-section sepa
rated from the walls of said hollow by an inter
Fig. 1 is a vertical section, somewhat diagram 30 vening border gap 23 affording the necessary
space for the collapse or contraction of the
matic, through a casting apparatus containing a
core It.
core which embodies one form of the present in
venticn;
To hold the core sections H and 12 in assem
bled position shown in Fig. 2, there is provided
Fig. 2 is a transverse section of the core taken
at one end of the core li! a core retaining head
on line 2—-2 of Fig. 1; and
Fig. 3 is a transverse section of another form 35 plate 25 shown in Fig. 1 having a circular or
hexagonal face groove 26. The upper ends of ~
of core embodying the present invention.
the
core sections l l and I2 have ?anges 21 ex
Referring to Figs. 1 and 2 of the drawing, the
tending in the plate groove 26 and abutting the
core Iii comprises a series of similar segments H,
outer peripheral wall of said groove in limiting
three being shown, separated by wedges 12.
These core sections I l and 42 are desirably made 40 expanded position of these core sections. The
of metal having high heat conductivity such as
groove 26 is wide enough to permit radially in
copper. Each of the core segments H has an
ward collapse of the core Ill.
outer circular conformation i3 and an inner
At its lower end, the core It seats on a retain
chordal surface it intersecting said circular con 45 ing base member 28 shown in the form of a mold
formation and slidably seating the wedges l2.
stool having a circular recess 30 for receiving the
The wedges [2 are approximately trapezoidal in
lower end of saidcore. The outer peripheral
cross-sectional outline with respective outer cir_
wall of the recess 39 by its engagement with the
cular conformation l5 forming continuations of
outer peripheries of the core sections II and I2,
the segment conformations l3 in expanded con
dition of the core shown in Fig. 2. Each wedge 50 limits radially outward movement of these sec:
tions to the position shown in Fig. 2, while per
l2 has a base it extending between the two
chordal surfaces M of respective ?anking seg
ments l l, and opposed inclined plane surfaces l7
slidably engaging said chordal surfaces respec
mitting limited radially inward collapsing move
ment of said sections under shrink pressure.
The metal core sections ill and l I are respece
55 tively'hollowed and provided with .end walls to
2,405,254
3
permit circulation of cooling liquid, such as water,
therethrough.
In Fig. 1 is shown the application of the core
ll! of Fig. 2 to a molding apparatus for produc
ing and shaping hollow ingots. This apparatus
comprises an outer tubular mold 35 desirably of
4
in the distributing head 61, and extends out
wardly through the base 56. The shaft 51 has
a central inlet duct 12 offset at its lower end for
communication with the recess 66 and an outlet
duct 13 offset at its lower end for communication
with the recess '18. At its upper end, the inlet
metal such as copper, and desirably provided with
duct 12 extends through the turntable 58 and
connects to the lower end of a pipe 15 passing
a jacket 36 to permit circulation of a cooling me
through the core block 22 and the upper core
dium such’as water through the hollow mold
retaining head plate 25. The upper end of this
10
walls. This tubular mold 35 is seated on the
pipe 15 is connected to a header 16 above the
stool 28 which also serves to seat the sectional *
core [0. The cooling liquid is distributed from
core 18 centrally in the interior of the mold. The a this header ‘I6 to the core sections H and I2 by
core l0 de?nes with the outer mold 35 an annu
respective pipes 11. Since the core sections H
lar mold chamber 38 of circular or any desired
and I2 are moved radially inwardly by the shrink
15 .
cross-sectional con?guration.
e '
pressure of the cooling cast metal in the mold
The deposition of molten metal in the mold
chamber 38 may be effected by any suitable man
ner, thus molten metal may be poured in the
chamber 38, the pipes 11 and 18 are desirably
made of suitable yieldable material to permit this
collapsing movement of the core sections.
conventional way from a ladle or other molten
The turntable 56 has an annular chamber 82
20
metal source or the metal may be produced di
‘communicating by ducts with the pipes 18 and
rectly in mold chamber 38. For instance, a series
also with theupper end of the outlet shaft duct
of circumferentially spaced consumable electrodes
13.
45 may extend into the mold chamber 38 and be
The distributing system described can also be
submerged in a blanket of ?oating flux 48 with
employed
to circulate cooling liquid through the
the lower ends of said electrodes spaced from the 25 stool 28 and the. outer mold 35. For that pur
deposited molten metal 4'1 by a gap. Current is
pose, the turntable 58 has a radial duct 85 con
discharged through the electrodes 45 and the
nected at its inner end to the turntable duct 12
metal 41 and across the intervening gap to pro
and at its outer end to one end of a pipe 86. The
gressively fuse the lower ends of said electrodes
other end of this pipe 86 leads into the upper
30
and produce the metal 41. Other ingredients to
inlet end of the mold 35. The lower discharge
impart to the metal 41 the desiredanalysis may
end of the mold 35 is connected to one end of
be delivered to the fusing zone of the mold cham
a pipe 81, the other end of which joins into the
ber 38. The electrodes 45 are fed and the current
outer end of a radial duct 88 in the turntable 50.
supply adjusted so as to maintain a current dis
The inner end of this radial duct 88 connects
charge across the gap of substantially constant - with the annular chamber 82 in the turntable 56.
characteristics.
Although one inlet pipe 86 and one discharge
,During the fusing operations described, the
pipe 81. are shown for the mold 35, it must be
mold is rotated slowly to distribute evenly the
understood that any number of these pipes may
metal 41 deposited in the mold chamber 38 and
be employed suitably distributed and arranged
to assure that the whole surface of the deposited 40 to obtain the most effective cooling of said mold.
metal is kept molten. This rotation of the mold
To circulate cooling liquid through the turn
may be effected in any suitable manner.
For
example, in the speci?c form shown, there is
provided a turntable 58 seating the mold stool 28
and carrying on its lower face a crown gear 5!.
Meshing with this crown gear 5! is a bevel gear
52 driven from any suitable source of power. This
turntable 50 is supported by means of thrust
bearings 53 on a bearing post 55 extending up
w wardly from a ?xed base 56. A shaft 51 depend- .
ing from and rigid with the turntable 59 is jour
nalled in the post 55.
The core block 22 may extend downwardly
through an opening in the mold stool 28 and
seat on the turntable 58 for rotation therewith.
The body of metal 41 is grounded or otherwise
connected to the current discharge circuit of the
electrodes 45. This electrical connection may be
effected, for example, by means of a conductor
ring or ?ange 68 rigid with and depending from
the turntable 50 and partially submerged in an
annular mercury well 6|. This mercury well 61
is ?xed to the post 55 and connected to a lead
62 in the circuit of the electrodes 45. The stool
28 and turntable 50 being of metal or other suit 65
able electrical conductive material, the body of
molten metal 41 will be connected to the current
discharge circuit of the electrodes 45.
The means for circulating a suitable cooling
medium, as for example water, through various
parts of the mold apparatus including the mold
core ID, desirably comprises an inlet pipe 65 lead
ing into the base 56 and connected to 'an ‘annular
table 58, said turntable has a hollow 90 with one
or more inlet connections 9i leading from the duct
85, and one or more outlet connections 92 joined
to pipe or pipes 81.
In the operation of‘the mold apparatus de
scribed, as the deposited metal 4'! solidi?es and
cools, the resultant shrinkage of said metal causes
compression of the core segments I l in a radially
inward direction. This shrinkage pressure causes
the’ core wedges 12 to slide radially inwardly
against the resisting action of the springs 28, so
that the core segments H are moved radially
inwardly and closer together. This collapse of
the core In permits it to be easily removed from
the cooled cast metal and to be reused for sub
sequent casting operations. When the core i8
is removed from the casting, the various sections
thereof will be restored to expanded condition
under the biasing action of the springs 28.
Although the core 10 of Fig. 2 has been shown
in Fig. 1 as applied to a speci?c mold apparatus,
it must be understood that as far as certain as
pects of the invention are concerned, this core
l8 maybe employed in connection with any other
suitable mold apparatus.
In Fig. 3 is shown another form of collapsible
mold core embodying the present invention. In
this form, four main core sections Ha are quad
rantly arranged and separated by wedge sections
12a. Each of these main core sections Ha has
an outer circular conformation 13a and a pair of
inner converging plane surfaces Ma On which
slide the wedges l2a. The core sections Ha and
75
let pipe 68 is connected to an annular recess ‘I8
recess 66 in a ?xed distributing head 61.
An out
2,405,254
5
6
I211 are hollowed to permit circulation of cooling
liquid therethrough, and are shaped to conjoint
ly de?ne a continuous outer cylindrical surface
in expanded position of said sections shown in
Fig. 3, and a central hollow of substantially square
cross-section. Extending in this core hollow is
a block 22a of substantially square cross-section
smaller in size than said hollow to de?ne with
arranged sections having outer circular surfaces
and inner plane substantially chordal surfaces,
and a wedge between each adjoining pair of seg
mental sections having inclined plane surfaces
seated on the inner chordal surfaces of said pair
of adjoining segmental sections and slidable
therealong to permit said sections to move radial
ly, the inclination of said wedge surfaces being
the inner walls of the core section a marginal
gap 23a affording the necessary space for the 10 such as to allow said wedges and said sections
to move radially inwardly out of molding position
collapsing movement of the core sections I la and
upon
application of compressive pressure by
I2a. ‘Springs 20a have one end retained in re
shrinking cast metal on said circular surfaces,
spective recesses 2| a of the core block 22a and
and means for yieldably resisting radially inward
the other end bearing against the bases of the
movement of said wedges.
wedges l2a to urge these wedges radially out
wardly. These springs 20a are provided at the
upper and lower sections of the core block 22a
to afford the necessary equilibrium. The recesses
Zla are desirably arranged with each pair of op
posed recesses in a different plane from the other
adjacent pair of opposed recesses, so that the
corners of the block 22a where these recesses
are disposed are not unduly weakened.
3. A collapsible mold core comprising three
similar substantially segmental circumferentially
arranged metal sections hollowed to permit cir
culation of a cooling medium therethrough, and
having outer circular surfaces and inner plane
substantially chordal surfaces, a metal wedge be
tween each adjoining pair of segmental sections
hollowed to permit circulation of a cooling me
dium therethrough, said wedge having inclined
The core of Fig. 3 can be arranged in a mold
as indicated in connection with the core [0 of
Fig. 1 to shape the hollow of a casting. As the
plane surfaces seated on the inner chordal sur
faces of said pair of adjoining segmental sections
and slidable therealong to permit said sections
core sections Ila are pressed radially inwardly
by the shrink pressure of the cooling casting, the
wedges l2a are forced radially inwardly to cause
to move radially, the inclination of said Wedge
surfaces being such as to cause said wedges to
move radially inwardly upon application of com
approachment of the main core sections lZa and
collapse of the core against the resisting action 30 pressive pressure on said circular surfaces, a block
in the interior space conjointly de?ned by said
of the springs 20a.
sections and said wedges, and springs between
As many changes can be made in the above
said block and said wedges urging said wedges ra
apparatus, and many apparently widely di?erent
embodiments of this invention can be made with
out departing from the scope of the claims, it is
intended that all matter contained in the above
description or shown in the accompanying draw
ing shall be interpreted as illustrative and not in
a limiting sense.
What is claimed is:
.
l. A mold core comprising a plurality of sec
tions having outer circular surfaces of the same
radius, wedges spacing said sections and automat
ically slidable radially inwardly upon the applica
tion of shrinkage pressure of the cast material on
the outer surfaces of said sections, a blockv in the
interior of said core, and spring means bearing
on said block and urging said wedges radially
outwardly.
2. A collapsible mold core comprising three
similar substantially segmental circumferentially
dially outwardly.
35
4. A collapsible mold core comprising four sim
ilar quadrantly arranged sections having outer
circular surfaces respectively, and each having a
pair of converging inner plane surfaces extend
ing away from its corresponding curved surface, a
wedge between each adjoining pair of sections
having inclined plane surfaces seated on the in
ner plane surfaces of said adjoining sections and
slidable therealong to permit said sections to
move radially, the inclination of said wedge sur
faces being such as to allow said wedges and said
sections to move radially inwardly out of molding
position upon application of compressive pressure
on said curved surfaces by shrinking cast metal,
and spring means urging said wedges radially out
wardly.
ROBERT K. HOPKINS.
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