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April 29, 1947.
E, N, GREENWELL
'
2,419,716
' MOLD ASSEMBLY FOR CENTRIFUGAL CASTING
Filed Sept. 13, 1945
525T EZTZVI Fr EE'ZZ WE //
f’atentecl Apr. 29, i947
UNITED STATES PATENT OFFICE
2,419,716
li/EOLD ASSEMBLY FOR CENTRIFUGAL
CASTING
Everett N. Greenwell, Valparaiso, Ind., assignor to
The Indiana Steel Products Company, Chicago,
111., a corporation of Indiana
Application September 13, 1945, Serial No. 615,988
I
14 Claims.
((31. 22-1135)
This invention relates to a mold assembly and I
more particularly to a mold assembly including
ceramic mold inserts of a refractory composition
2
of relatively high melting points.
produce castings of ?ne grain for physical
strength, and with such a design, the present
form of mold assembly may not be entirely suited.
On the other hand, the present type of mold as
In accordance with the principles of my inven
tion, preformed mold inserts are employed to pro
sembly gives better surface characteristics and
greatly facilitates the casting operation.
vide accurately dimensioned mold cavities. The
mold cavities found most satisfactory are those
It is therefore an important object of this in
vention to provide a mold assembly in which a
for the centrifugal casting of metals and alloys
plurality of preformed, accurately dimensioned
tightly in superimposed
relationship within sector-shaped members that
made of a refractory composition by a molding,
die pressing or other forming operation. The
mold inserts so formed may then be baked or
._ mold inserts are held
are maintained in the form of a ring, or annulus,
?red to develop a high temperature bonding prop
erty. These-mold inserts are arranged in asso
ciated relationship so as to form the mold cavities
within an outer cylindrical shell, thereby facili
tating the setting up and dismantling of the mold
assembly.
with separate gates leading thereinto.
In order to facilitate the assembling and dis
mantling of a mold assembly, I employ sector
shaped members for receiving and positioning the
mold inserts in superimposed relationship circum 20
ferentially of the pouring cavity of the mold as
assembling and dismantling.
sembly.
, It is a further important object of this inven
These sector-shaped members, which
It is a further important object of this inven
tion to provide a mold assembly for use with
highly refractory ceramic mold inserts, and in
which the insert carrier is segmented for ease of
tion to provide a mold assembly for use in ‘the
may also be formed of a refractory ceramic com
precision casting of high melting point metals
position, are arranged Within a tapered cylindri
cal shell to provide an annulus about the pouring 25 and alloys by the use of centrifugal force, which
mold assembly presents no metal surfaces for
cavity, and the individual mold inserts are
contact with the cast metal or alloy and therefore
insures better surface characteristics of the cast
stacked in the cylindrical cavity provided for the
purpose by the assembled sector-shaped members.
mgs.
By the use of such an arrangement, the cast
metal does not touch any metal‘ surfaces and, 30 It is a further important object of this inven
tion to provide a mold assembly for use in centrif
therefore, does not become unduly chilled during
ugal precision casting, in which the mold may be
the casting operation. The individual mold in
easily assembled and dismantled because of the
serts, when stacked one upon the other, provide
use of a segmented carrier for .the individual
individual gates into the ultimate mold cavities
molds inserts, the arrangement being such as to
of the inserts.
.
substantially eliminate any possibility of dam
After the articles have solidi?ed, they can be
removed without destruction of the sector
shaped members and without damage to the cast
aged castings.
Other and further important objects of'this
invention will be apparent from the disclosures in
ings themselves. Heretofore, when an integral
and the accompanying drawing,
carrier or holder for the mold inserts wasem 40 thespeci?cation
On'the drawings:
ployed, it took as much as twenty minutes or
Figure 1 is a top plan view, partly broken away,
more to knock out the castings from the mold
of the mold assembly embodying the principles
and a considerable portion of the castings were
damaged.
of my invention.
With the segmented carrier of the
present invention, however, the mold assembly
can be dismantled after casting in ?ve minutes
or less and at the same time the possibility of
damaged castings is practically eliminated.
45
7
Figure 2 is an enlarged sectional view taken
substantially along the line II-lI of Figure ,1,
with parts in elevation and parts broken away.
Figure 3 is a’perspective view of a sector-shaped
member of the carrier, or holder, for the indi~
Furthermore, the elimination of any metal sur
>
face for contact with the cast metal reduces the 50 vidual mold inserts. Y
As shown on the drawings: .
chilling of the castings and reduces, therefore, the
The reference numeral 10 indicates generally
likelihood of cold shuts or cracked castings being
a mold assembly embodying the'principles of my
produced, as was the case, when using metal parts
invention. Said mold assembly comprises , a
in the mold assembly that came into contact with
the cast metal. Oftentimes'it is necessary to 55 mounted,_cylindrical receptacle _l I having an open;
flanged, upper end l2 and aclosed bottom wall
2,419,716
l3. The receptacle H is adapted to be mounted
upon a centrifugal table l4 driven through a
shaft l5.
4
such as alumina, or the like, and suitable low and
high temperature bonding agents, is placed in a
master mold and pressed to the desired size, shape
and dimensions, including those with the recesses
therein to form the mold cavities MC. After being
molded to shape and dimensions, the “green"
trifugal table M by means of bolts H. The re
mold inserts are then dried, baked and ?red to
ceptacle H has bolted to its underside a ?anged
form refractory or ceramic mold inserts of the
ring [8, the ?anges ill of which are adapted to
type illustrated in Figures 1 and 2. The recesses,
be engaged by the clamping members 16. Bolts
such as the recesses forming the individual mold
20 secure the ring M3 to the undersurface of the 10 cavities MC, are in this way very accurately di
For mounting purposes, the table Id is provided
with clamping members it secured to the cen
bottom wall I3. An annular insulating gasket 2|
mensioned, allowance being made for the forming
may be inserted between the ring l8 and the bot
of the mold inserts for change of size during the
tom wall l3 to reduce the amount of heat con
?ring step for‘contraction of the cast metal arti
ducted from the mold assembly to the centrifugal
cle upon cooling, so that the ?nal cast article can
15 be kept within very close tolerances indeed.
table l4.
A graphite disk 22, or a disk of any other rela
After the ring 24, inner ring R and mold and
tively refractory and non-heat-conductive mate
?ller inserts 29 and 33 have been assembled within
rial, is positioned within the casing H against the
the casing H above the graphite disk 22, an as
bottom wall l3. An annular mold insert ‘fixture,
bestos or other heat insulating and highly re
or carrier, indicated generally by the reference 20 fractory gasket 36 is laid over the top of the
numeral 23 is then inserted into the casing H
assembled ring R, and the spacing ring 31 inserted
for positioning on top of the graphite disk 22.
into the top of the casing H to rest upon the
Said annular mold insert ?xture, or carrier 23
gasket 36. A clamping ring 38 is laid on top of
includes a ring 24 having an outer cylindrical
the spacing ring 31 and clamped down by means
25
surface for ?tting within the casing II and an
of J-shaped clamping ‘bolts 39 that pass through
inner tapered surface 25. The ring 24 may be of
the flanged upper portion l2of the casing H and
metal or other suitable material and may be cast
are held in place by means of nuts 40.
or formed integrally. Individual, sector-shaped,
The assembled mold provides a central pouring
refractory members 26 are arranged within said
cavity
P-C, into which the molten metal is poured
shell 24 to form together a ring R within the ring 30 during the ‘casting operation. The mold assem
213. Each of the individual, sector-shaped mem
bly P is set to rotating upon the centrifugal table
bers 28 (Figure 3) is formed of baked ceramic
[4 at a suitable speed, usually between 400 to 1700
material of highly refractory composition, al
R. P.
and molten ‘metal is poured into the
though for some purposes the members may be
mold assembly ‘through the pouring cavity P-C.
formed of metal or a metal alloy. As shown, each 35 Due to the high speed of revolution of the mold
sector-shaped member 26 has an outer frusto
assembly, the molten'metal is thrown outwardly
conical surface 21 that conforms to the taper of
and upwardly, so that the cross-section of the
the inner surface 25 of the ring 24. The purpose
surface of ‘the'imolten'metal, after the individual
of this tapered surface arrangement is to insure
mold cavities MC have ‘been ?lled, takes sub
that the sector-shapedlmembers 26 are locked 40 stantially the shape of the pouring cavity P-C
except that the surface becomes slightly tapered
into place upon insertion of a ring R within the
downwardly and inwardly. Due to the centrifu
ring 24. Each of the members 26 is further pro
vided with a segmental, right-cylindrical surface
gal force withiwhich’the molten metal is thrown
28 on either of its radial faces for cooperation 45 outwardly, metal enters each of the individual
cavities MC through the gate 34,‘to ?ll said in
with similar segmental-cylindrical surfaces to
dividual cavities ~and~the gate itself. Since the
form cylindrical cavities-C for the reception of a
mold ‘inserts are clamped tightly together by
plurality of superimposed mold-inserts 29.‘ The
means of the clamping ring ‘38 and spacing ring
inner surfaces 30 of the members 26 may be plane
31, together with the J-shaped bolts 39 and nuts
or rounded, but as shown are plane and are pro
vided with beveled edges 3-! ‘leading toward the 50 40, no metal‘oan force its ‘way in between :the
upper surfaces n32'and‘the under surfaces of the
cavities C.
>_
.
insert ?ller '33, except,rof course, at the'gates34.
Each'of the mold inserts 29 is preferably in the
The upper and lower surfaces‘ of the castingssare
form of a relatively short cylinder having a diam
thus smooth except for the portions of metal that
eter that enables it to besnugly received within
one of the cavities C. As illustrated in Figure 2, 55 ?ll the ‘gates ‘34.
i
.
After the casting ‘operation is'co‘mplete‘d'iand
each mold insert 29 is provided with a plane-upper
the‘cast metal -alloy"hashad ‘an opportunity to
annular edge 32 upon which rests a ?ller insert
solidify, the mold assembly is taken apart and
33. Said ?ller insert 33 is also formed of a re
fractory ceramic composition and is provided-with 60 the segmentalv annular ring ‘R dismantled. Iflthe
amount or molten. metal poured hasfbeen Iclosely
a cut away portion forming a gate 34 for entrance
gauged, ' there "will: be only‘, a thin; shell of metal
of the cast metal into the individual mold» cavity
over the inner ‘periphery ‘of the ‘segmental annu
MC of the adjacent mold insert 29 therebelow.
lar mold=insert carrying ring R, and this can‘be
As shown, each of the mold inserts>23 and the
?ller insert 33 is provided with an axially extend
readily‘ broken." away ‘at‘therestricted portions of
ing bore and a cylindrical rod 35 of graphite or 65 the metal in gates“; "Each‘stack of mold inserts
the like is inserted through the aligned bores
and ?ller inserts i's'then'freed by‘ removing {the
when the inserts are in superimposed vposition
sector-shaped Imemb'ers ‘26 ‘from between'isaid
within the cavities C. It will be understood, how
stacks,"and“eachz stack is’ then broken up to‘ free
ever, that the showing is merely illustrative of one
the individual cast: articles. The ‘portions’ of’ the
type of mold insert and that'other forms may 70 graphite; rod!‘ 35:1arie" either.’ forced: or drilled out
to leave J the, centralrop'enings‘ formed ‘thereby ‘in
be used with or without the graphite rod ‘35 to
form holes in the ?nal casting.
the. individual‘ castings,
,
.
In making the mold insertsiused in my ‘assem
‘The ‘moldiassem‘blmof' my invention thus makes
bly, a composition comprising a substantially dry
it possible-to casti various metals and alloys, in- l
mixture of a ?nely‘divided refractory material, 76
52,419,716
eluding highly refractory metals and alloys, in
relatively small shapes to close tolerances. While
it is not necessary to resort to centrifugal casting
to carry out the method of my invention, it is
advantageous to make use of centrifugal casting
in the case of high melting point metals and
alloys that are sluggish in their ?ow even at tem—
5. In a casting assembly, a casing; ariiig therein having a tapered inner wall, a plurality of in‘
dividual sector-shaped members forming together
i, an annular ring having a tapered wall conform-V
ing with the tapered wall of said ?rst ring and
having individual recesses spaced circumferen
tially thereof, a plurality of mold inserts mounted
peratures above their melting points. This is
in superimposed relationship within said recesses
particularly true of certain permanent magnet a1
and providing mold cavities and gates leading
loys, such as alloys of the “alnico” type contain 10 thereinto, and means for holding said mold in-_
ing aluminum, cobalt, nickel and sometimes small
serts and sector-shaped members in tight asso
proportions of other metals. Where a metal or
ciation.
alloy has a relatively low'melting point or is rela
6. In a mold assembly an annular member hav
tively ?uid at easily obtainable temperatures, the
ing recesses spaced about the inner periphery
casting may be carried out in a stationary mold, 15 thereof and openings into‘said recesses, a plu
or with the use of suction or pressure, as desired.
rality of mold inserts stacked one upon another‘
The form and arrangement of my mold assem
in each of said recesses, said molds forming to—
bly greatly facilitate the casting operation since
gether mold cavities and gates alined with said“.
it makes it easier to assemble and dismantle the
openings and leading into said cavities and means:
mold before and after casting, respectively, Fur
for holding said mold inserts in close contact with,
thermore, as already pointed out, there are cer 20 each other.
tain advantages in so arranging the mold assem
'7. In a mold assembly an annular member‘
bly that no metal come into contact with the
having recesses spaced about the inner periphery’
cast metal or metal alloy. This is a continuation
thereof and openings into said recesses, a pluin-part of my copending application Serial No.
25 rality of mold inserts stacked one upon‘ another‘
538,61e, ?led June 3, 1944, entitled “Mold Assem
in each of said recesses, said molds forming to
bly for Precision Casting.”
gether mold cavities and gates alined with said
It will, of course, be understood that various
openings and leading into said cavities, means
details of construction may be varied through a
for holding said mold inserts in close contact
wide range without departing from the principles
with each other and a casing for retaining said
of this invention and it is,_ therefore, not the 30 annular member during centrifugal casting of
purpose to limit the patent granted hereon other
molten material into said mold cavities.
wise than necessitated by the scope of the ap
8. In a casting assembly, a casing, a ?xture
pended claims,
mounted therein having a relatively deep recess
I claim as my invention:
with a restricted opening thereinto the full depth
1. A mold assembly comprising an open-ended 35 thereof, a plurality of mold inserts ?tted into said
shell of generally cylindrical shape, a plurality of
recess one adjacent another, said mold inserts
sector-shaped members within said shell and
forming together a plurality of mold cavities and
forming together a ring having a central pouring
gates alined with said restricted opening and lead
cavity and a plurality of circumferentially spaced
ing into said cavities, and means for holding said
40
smaller cavities, and a plurality of mold inserts
mold inserts tightly together,
arranged in superimposed relationship within said
9. In a casting assembly, a cylindrical casing
smaller cavities and forming together individual
open at the top and having a closed bottom wall,
mold cavities having gates leading thereinto from
a liner in the bottom thereof, an annular ?xture
said pouring cavity.
45 resting on said liner and provided with a plu
2. In a. mold assembly, an annular segmental
rality of recesses spaced about the inner periph
member providing circumierentially spaced re
ry thereof and having restricted radially ex
cesses, a plurality of mold inserts stacked one
tending full length openings, a plurality of mold
upon another in each of said recesses, said mold
inserts ?tted into said recesses, said mold inserts
inserts forming together mold cavities and gates
50 forming together a, plurality of mold cavities and
leading into said cavities, and a ring of generally
gates alined with said restricted openings and
cylindrical shape holding said segmental member
leading into said cavities, an annular member
and mold inserts in assembled relationship.
overlying said ?xture to close the upper ends of
3. In a mold assembly, an annular member
composed of a plurality of sector-shaped parts
providing circtunferentially spaced mold insert
receiving recesses, a plurality of mold inserts
said recesses and means for clamping said ?xture
55 between said annular member and said bottom
liner.
10. In a casting assembly, a cylindrical casing
open at the top and having a closed bottom wall,
cesses, said molds forming together mold cavities
a non-heat conductive liner in the bottom there
and gates aligned for leading into said mold cavi 60 of, an annular ?xture resting on said liner and
ties, and means for holding said mold inserts in
provided with a plurality of recesses spaced about
close contact with each other and for retaining
the inner periphery thereof and having restricted
said segmental annular member in association
radially extending full length openings, a plu
with said mold inserts for the centrifugal casting
rality of mold insert-s ?tted into said recesses,
of molten material into said mold cavities,
65 said mold inserts forming together a plurality of
ll. In a casting assembly, a casing, a ring there
mold cavities and gates alined with said restricted
in having a tapered inner wall, a plurality of
openings and leading into said cavities, an annu
individual sector-shaped members forming to
lar member overlying said ?xture to close the
gether an annular ring having a tapered wall con
upper ends of said recesses, means for clamping
forming with the tapered wall of said ?rst ring 70 said ?xture between said annular member and
and having individual recesses spaced circum~
said bottom liner and means for rotating said
ferentially thereof, and a plurality of mold in
casing about its axis to cause molten material
serts mounted in superimposed relationship
poured onto said bottom liner to be thrown cen
within said recesses and providing mold cavities
trifugally through said restricted openings and
and gates leading thereinto.
gates into said mold cavities.
stacked one upon another in each of said re»
8
ery thereofrparallel to the axis of saidmember
11. In a casting assembly, a cylindrical casing
open at the top, a non-‘heat conductive refractory,
liner for the bottom of said casing, an annular
?xture resting on said liner, saidf?xtu're having
a plurality ofrbor'es spaced about the inner periph-‘
andihaving openings in the inner periphery into
saidgrecess‘es, ‘a plurality of preformed mold in
seas‘. ‘arranged in contac?with one another in
. said i-ecess'es,5said"rnold inserts forming'tog’étlieri
' a' plurality of '"mold‘ cavities and gates‘. leading
erythereof and opening therethrough to provide
restricted full length entrances to said bores, a
plurality of ceramic mold inserts ?tted into said
bores one upon another, said mold inserts form
ing together a plurality of mold cavities‘with 10
gates alined with said restricted entrances and
means closing the upper ends of said bores but
providing an opening through which molten ma
terial can be poured onto said bottom liner to 'be
centrifugally thrown through said restricted en
trances and said gates into said mold‘ cavities;
said'iiiserts’ in tight contact with each other.
'14. Inacentrifugal mold assembly an‘annular
member having a closed outer periphery and 'de'-'
?ningbores having lateral openings through the
innenperipheryvinto theinterior of said member,
a plurality .of preformed mold inserts‘packed in
15
12. In a, casting assembly, a cylindrical casing
open at the top, a non-heat conductive refractory
said bores‘, said mold-inserts forming togethér‘la“
plurality of mold ‘cavities and gates alined'with
said‘lateral openings leading into said cavities;
means'hol'd'ing said inserts’ in tightly packed relae
tionsliipfandnieans for rotating said m'ol'dYas
liner for the bottom of said casing, an annular
?xture resting on said-liner, said ?xture having
a plurality of bores spaced about the inner periph
ery thereof and opening therethrough to provide
restricted full length entrances to said bores, a
thereinto ‘for receiving ?uid material introduced
through’ 'said openings, and means for holding
2.0 ,
semblyhbout', its axis to cause ?uid ‘material
poured into the interior thereof to be thrown
radially throughsaid? lateral openings andualin‘ed
gates‘ into‘saidimold cavities.
plurality of ceramic mold inserts ?tted into'said
’ "
"
'
EVERETT N. GREENWELIiQ
bores one upon another, said mold‘inserts forming
together a plurality of 'mold cavities with‘ gates
REFERENCES CITED
alined with said restricted entrances and ‘means
The‘ following references are of record in the
clamping said ?xture against said liner andiclosé
?le :ofthis patent:
ing the upper ends of 'said'bores but providing
an opening through which molten material .can 30,
UNITED STATES PATENTS
be poured onto said bottom liner to be centrifu-'
Number Name a
Date
gally thrown through said restricted entrances
and said gates into said mold cavities. '
'
13. In a mold assembly, an annular. member
having,r recesse'swspaced about’ the inner periph 3a ,
2,299i860 '
Stoo‘dy ___________ __ Oct. 27; 1942'
359,484
Whitley __________ -_ Mar, 15, 1887»
2,027,963
De Bats _________ __ Jan. 14,1936
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