close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2112110

код для вставки
March 22, 1938.
0'. ‘F. MARVIN
2,112,110
APPARATUS FOR MAKING TUNGSTEN CARBIDE CASTINGS
Original Filed March 19, 1932
-
'
'
.E
jlql
AS’
a) //.o ,7
43'
45/.
‘N
V.
‘Q‘Oq
. [NVENTOR
Orr/7 ’ . $110}?
1/,
M
ATTO R N EV
2,112,110
Patented Mar. 22, 1938
UNITED STATES
PATENT OFFICE
2,112,110
APPARATUS FOR MAKING TUNGS'I'EN
CARBIDE OASTINGS
' Orrin F. Marvin, Los Angelcs, CaliL, assi'gnor to
Mills Alloys, Inc., Los Angeles, Calif., a corpora
tion of Delaware
Original application March 19, 1932, Serial No. .
599,938, now Patent No. 2,028,911 dated January
28, 1936. Divided and this application July 15,
1935, Serial No. 31,304
8 Claims. (Cl. 22-—65)
ing this heat for the desired period and prevent
This invention relates to a production of sharp
ing unequal or deleterious or partial cooling.
ly de?ned cast bodies from dif?cultly fusible met
Although I prefer to utilize tungsten carbide
als, such for example, as tungsten carbide and
without the addition of any other element, a
the like, and more particularly to an improve
small percentage of free carbon or of other ma.
5 ment over the co-pending application to Oscar L.
Mills for a. Tungsten carbide product and Process terial such as boron, silicon, cobalt, nickel or
of making same, Serial No. 455,732, ?led January chromium may be employed, but only to a spar
ing extent, because such admixtures tend to de
17, 1931.
stroy the copper parts of the mold. Such alloy
This application is a division of application Se
ing materials, which of course tend materially 10
10 rial No. 599,938, ?led in my name on March 19, to reduce the hardness of the product, are not
1932, now Patent No. 2,028,911, issued January
28, 1936 and entitled Apparatus and process for essential in my process, because I secure the de
sired structure due to my improved treatment
making tungsten carbide castings.
of the molten material.
'
In the above mentioned co—pending aplica
15 tion of Oscar L. Mills a process is described for
producing a cast article of manufacture from
molten tungsten carbide which is characterized
by a ?ne grained structure.
In this process, a
molten tungsten carbide mass is first produced
at a temperature above its melting point; as for
2 O example, by the aid of the inventions disclosed
in the prior patents to Oscar L. Mills, No. 1,718,
558, issued July 2, 1929 and No. 1,721,966, issued
July 23, 1929. This mass preferably has, by
weight, not less than 2 percent of carbon, ‘nor
more than 6 percent thereof.
When this material is thoroughly and com
pletely molten, as in a carbon crucible capable of
accommodating at least several pounds thereof,
it is poured into a mold of the desired con?gu
30
ration, and subjected to pressure for the pur
pose of securing a ?ne grain structure. ' This is
accomplished by the aid of centrifugal force;v
which is produced by providing a rotating mold
structure, which in rotating throws the molten
material against the walls thereof.
'40
I have found that a uniform and ?ne grained
product can be obtained by the use of a double
or combination mold structure, comprising es
sentially an inner graphite mold proper and an
outer mold or support of copper or silver, with
the application of pressure, as for example by
centrifugal force. This double mold allows the
casting to chill slowly enough in order to re
45 duce the possibility of producing internal strains.
The graphite shell comprising the mold proper is
made so that it retains the heat for a suf?cient
period to effect this result; and this heat reten
tion property must be enhanced by the aid of
further heat insulation, as by an air space, be
tween the copper and the graphite mold. ‘Fur
thermore, the insulation acts to keep the graphite
mold from transmitting heat from the cast alloy,
except at a desired retarded rate, thereby retain
55
My invention possesses many other advan
15
tages. and has other objects which may be made
more easily apparent from a consideration of
one embodiment of my invention.
For this pur- ,
pose I have shown one form in the drawing ac
companying and forming part of the present 20
speci?cation. I shall now proceed to describe
this form in detail, which illustrates the general
principles of my invention; but it is to be under
stood that this detailed description is not to be
taken in a. limiting sense, since the scope of my 25
invention is best de?ned by the appended claims.
Referring to the drawing:
Figure 1 is a diagrammatic side elevation of
an apparatus utilized in my invention;
Fig. 2 is a fragmentary plan view thereof;
Fig. 3 is a fragmentary detailed sectional view
of a mold used in practicing my processyand
Fig. 4 is a. section thereof taken substantially
along the plane 4—4 of Fig. 3.
A molten tungsten carbide mass is ?rst pro 35
duced as by the aid of the invention disclosed by
the prior Patents 1,719,558 issued July 2, 1929,
and 1,721,966 issued July 23, 1929, to Oscar L.
Mills.
This mass is heated to a. temperature
above its melting point, and has, by weight, not 40
less than 2 percent of carbon, nor more than 6
percent thereof in the preferred form. It can be
alloyed with other metals, but preferably there
should not be more than 2 percent by weight of
such materials or other impurities. Among such 45
alloying metals may be mentioned the iron group,
chromium, molybdenum, tantalum, boron, sili
con, thorium and titanium.
When the mixture is thoroughly and com
pletely molten, as in a carbon or graphite cruci
ble capable of accommodating at least several
pounds of the material, it is poured into a mold
of the desired con?guration, and subjected to
pressure for the purpose of securing a sharply
de?ned product with a ?ne grain structure. The
50
9,112,110
material is heated to a very high temperature;
somewhere in the neighborhood of 5000lto 6000
degrees Fahrenheit, in order to put it in the
plastic or fluid state.
,
I prefer to cast the molten material in a mold
that is capable of gradually and uniformly ab
sorbing and transferring the heat from the prod
uct. Combination molds having a refractory
mold proper made from graphite and an outer
10 surrounding copper or silver jacket or mold are
admirably suited for this purpose. Graphite
will not materially react with the molten mass
and due to its low heat conductivity gradually
absorbs and transfers heat away from the prod
15 uct and thus aids in producing the desired cast
ing without internal strains. The thickness of
the graphite mold is determined in accordance
with the mass of the casting. In general, the
larger the casting, the thicker this mold should
20 be.
While the material is still molten, it is sub
jected to pressure, as hereinabove set forth. A
convenient way of accomplishing this is by the
aid of centrifugal force. Thus the mold struc
25 ture can be so arranged that it can be rotated
to throw or urge the molten mass against it and
in the graphite mold proper to cast the desired
sharply de?ned product.
‘
I have indicated in the present instance a com
30 bination mold structure that is capable of cast
ing a product such as a hollow cylinder; how
ever, as will be hereinafter set forth, other
sharply de?ned products can be cast.
The combination mold structure I 0 comprises
35 an outer shell or mold formed of copper, silver
or the like, and an inner graphite mold proper I I.
The outer mold I0 consists of a pair of hol
lowed out members I2 and I3 which when super
imposed in abutting relationship, de?ne a space
40 in which the mold proper I I resides, and which
forms a sprue for the passage of molten metal to
the mold proper. There is a mold at each end
of the member Ill. The mold proper may be
con?ned in this space as by a pair of end mem
45 bers I4 formed of graphite, one at each end of
member ID. Each of these end members may
be provided with inwardly extending corruga~
tions or ribs I 5 which cooperate with one end of
the mold proper to de?ne air spaces I6’. A pair
50 of rigid L-shaped metallic end members or
brackets I6 and I1 abut against the graphite end
members It and overlie the ends of the members
I2 and I3. The rigid end members I6 and I‘! are
rigidly secured to the outer mold ID as by bolts I8
55 and I9 extending therethrough and into the
channel member I3 in order to prevent the
graphite end members I4 from becoming dis
placed or discharged during rotation of the mold.
This outer mold, as thus far described, is rigidly
60 secured to a heavy metallic support or base 20
as by bolts 2I and 22.
The top member I2 of the outer mold can be
made relatively immovable with respect to the
lower member I3 as by a pair of hooks 23. The
65 hooks 23 cooperate with lugs 24 formed on the
sides of the top member I2, and the legs thereof
extend downwardly through openings 25 in the
supporting member 20. A pair of interconnect
ing levers 26 are pivotally secured at one end
70 to the ends of the legs of the hooks 23.as at 21,
and are also pivotally secured at an inter
mediate point to a pair of depending lugs 28
formed integral with the base 20. It is apparent
that by a single downward movement of the
76 levers 26, the hooks 23 will be lifted upwardly out
of engagement with the lugs 24 and permit the
relative movement and separation -of the top
member I2.
.
The upper member I2 can have a large central
aperture 23 to permit the pouring of the molten
material into the closed outer mold, which is ro
tated about a vertical, central axis, in order to
throw the material under pressure into the mold
proper II. The pressure thus attained may be
of the order of 0 to 200 pounds per square inch,
although higher or lower values could be used.
10
The lower member l3 can have a large saucer~
like depression 30 in the top face thereof imme
diately below the aperture 23 in order to permit
the molten material poured in to accumulate 15
therein.
The mold proper II is adapted to be positioned
in the outer mold III in the space de?ned by
members I2 and I3, one at each end thereof,
although it is readily apparent that more than 20
one can be so positioned by simply changing the
inner contour of the outer mold.‘ The mold
proper is formed completely of graphite and is
shown in this instance as comprising a. hollow
tubular shell 3| having upstanding end portions 25
or ?anges 32 and 33 which abut against the inner
periphery of the members I2 and I3. The shell
3| is made of the right thickness to assure a
gradual but not too slow cooling of the molten
material. In order to prevent the sagging or 30
breaking of this shell in case it is made from thin
material, reinforcing wire strands 34 can be
wound therearound, and a graphite ring 35 is
inserted between the shell and the outer mold
intermediate the ends of the former. The air
space 3 I ' between the shell and outer mold serves
as a heat insulation and thus further aids in
preventing the quick chilling of the- molten mass.
Rear and forward graphite end members 36
and 31 respectively, are inserted in inner pe 40
ripheral recesses formed in the sleeve 3|, and a
graphite core 38 extends through these end mem
bers and serves to de?ne therewith and with the
inner periphery of the shell a space in which the
material is to be cast.
The end member 36 as 45
well as the ?ange 32 abut against the tips of the
ribs I5 and form with the members I4 the air
spaces I6’.
These spaces serve as heat insula
tion spaces to prevent the quick transmission of
heat from the mold proper to the copper por 60
tions I2, I3.
The forward end member 31 is provided with
gates or ports 39 through which the molten ma
terial is forced into the space de?ned by the mold
proper upon rotation. Both of the end members 65
may be provided if desired with central recesses
40 and 4| which provide a space for the forma
tion of bosses on the ends of the cylinder to be
cast.
It is apparent that the mold proper I I is in 60
serted in the outer mold I0 prior to the pouring
in of the molten material.
This can be accom
plished by removing member I2 in a manner
already outlined.
To provide the above mentioned rotation, I 65
show in this instance a shaft 42 joined to the
bottom of the base 20, that can be rotated by
any source of motion. For example, in Fig. 1,
I show shaft 42 supported in a bracket structure
43 on table 44, and an electric motor 45 con
veniently supported under the table, which drives
the shaft.
-
70
.
A product, such as a cylinder, formed in the
manner above described, is permitted to remain
in the mold proper for a. short interval of time 75
1’
‘
-
-
3
2,112,110
to permit the gradual and uniform cooling there
4. A mold for casting sharply de?ned castings
. of, Usually this interval is attained by the neces
from highly refractory di?lcultly fusible metallic
sary delay incident to the opening of the mold.
As hereinabove set forth, the arrangement of a.
combination mold in the manner and of ma
terials described, assures the gradual, but not too
slow, removal of heat from the product. When
the product has assumed a self-sustaining form,
it is placed in a space where it is still further
10 gradually cooled. This can be accomplished by
removing member II in the manner described.
A space for gradually cooling the product to
room temperature can be formed by a box 46 that
contains some powdered material that retains
15 heat long enough to insure slow cooling. For
example, a mass of silica ?our 41 can be used in
box 46. If desired, the sides and bottom of the
container can be provided with a layer of heat
insulating material. This slow cooling effectively
20 prevents internal strains.
.25
material, comprising an inner graphite mold
proper and an outer mold surrounding said mold
proper and in limited heat exchange relation
thereto, said outer mold comprising a pair of
members, means forming an opening in one of
said members for the introduction of the molten
material, said mold proper comprising a shell
having end members, means forming gates in 10
one of said end members for the entry of the
molten material into said mold, a rotatable sup
port for said outer mold, and means for rapidly
rotating said outer mold to urge the material un
der pressure into said mold proper.
5. A mold for casting sharply de?ned castings
from highly refractory di?‘icultly fusible metallic
material, comprising an inner graphiite mold
proper and an outer mold surrounding said mold
proper and spaced therefrom, said outer mold 20
By proper‘ choice of the relative dimensions of
the mold I I and the outer casing l2--l3, the rate
of cooling can be predetermined. Thus the air
comprising a pair of members, means forming an
opening ‘in one of said members for the introduc
tion of the molten material, said mold proper com
spaces I6’ and 3|’ can be made of proper size, as
well as the area of contact between the annular
prising a shell having end members, supports for
said shell, means forming gates in one of said end 25
members for the entry of the molten material
into said mold, a rotatable support for said outer
mold and means for rapidly rotating said outer
mold to urge the material under pressure into
said mold proper.
30
surface of ?anges 32, 35, 33 and the inner surface
of the structure l2--l3 can be made to ?t the re
quirements. In fact, those annular surfaces of
contact can be multiplied or reduced in accord
30 with these requirements.
I claim:
'
.
1. A mold for casting sharply de?ned castings
6. A mold for casting sharply de?ned castings
from highly refractory, diii‘lcultly fusible metallic
from highly refractory di?lcultly fusible metallic
material, comprising an inner graphite mold
material, comprising an inner graphite mold
35 proper and an outer mold surrounding said mold
proper and spaced therefrom, said outer mold
comprising a pair of hollow members, and means
proper, and an outer mold having an internal
forming an opening in one of said members for
the introduction of the molten material.
40
2. A mold for casting sharply de?ned castings
from highly refractory dif?cultly fusible metallic
material, comprising an inner graphite mold
proper and an outer mold surrounding said mold
proper and spaced therefrom, said outer mold
comprising a pair of members, means forming
an opening in one of said members for the intro
duction of the molten material, said mold proper
comprising a shell having end members, and
means forming gates in one of said end members
for the entry of the molten material into said
mold.
3. A mold for casting sharply de?ned castings
from highly refractory di?lcultly fusible metallic
material, comprising an inner graphite mold
proper and an outer mold surrounding said mold
Proper, said outer mold comprising a pair of
members, means forming an opening in one of
said members for the introduction of the molten
material, said mold proper comprising a shell
50 having end members, supports for said shell, and
means forming gates in one of said end members
for (the entry or the molten material into said
mol .
surface supporting said inner mold and project
ing beyond the mold to form a sprue for molten
material to be passed into the mold proper.
7. A mold for casting sharply de?ned castings
from highly refractory, dif?cultly fusible metallic
material, comprising an inner graphite mold 40
proper, an outer mold having an internal surface
supporting said inner mold and projecting be
yond the mold to form a sprue, a rotatable sup
port for the outer mold, means permitting intro- _
duction of molten material into said sprue while
said mold is being rotated, and means for rapidly
rotating the outer mold to urge said molten ma
terial along the sprue and into the mold proper
under pressure.
'
v8. In a device for casting a carbide of the
chromium group, a mold of carbon material, and
means forming an outer enclosure for the mold,
said mold and enclosure having a limited area of
contact with each other, said area being deter
mined to fix the rate of heat transfer from the 55
cast article through the enclosure, a rotatable
support for the outer enclosure, and means to
rotate the outer enclosure, said outer enclosure
having means to which pre-molten carbide is
adapted to be passed during rotation of the en
closure.
ORRIN F. MARVIN.
Документ
Категория
Без категории
Просмотров
0
Размер файла
571 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа