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Патент USA US3024517

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March 13, 1962
J. B. GERO
3,024,507
METHOD OF VACUUM CASTING
Filed July 30, 1959
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INVENTOR
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ATTORNEY
March 13, 1962
J. B. GERO
3,024,507'
METHOD OF VACUUM CASTING
Filed July-30, 1959
2 Sheets-Sheet 2
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INVENTOR
a.‘ 23/01”
.
BY
.
M-
ATTORNEY
I"
United States "atent O
3,024,501
Patented Mar.- 13, 1962
2
1
from each ladle or heat, a series of vacuum chambers
are necessary further complicating the problem.
It is an object of the invention to improve methods
John B. Gero, Magnolia, Mass, assignor to Gero Metal
and apparatus for vacuum casting and to devise means
lurgicai Corporation, Boston, Mass, a corporation of 5 for more effectively and quickly establishing and main
Delaware
taining a vacuum in order to produce quality steels with
Filed July 30, 1959, Ser. No. 830,983
desirable magna?ux and micro-cleanliness ratings and
3,024,507
METHQD 6F VACUUM CASTING
5 Claims. (Cl. 22-209)
better physical properties to permit production vacuum
pouring of multiple large or small ingots from one heat
This invention relates to methods and apparatus for
vacuum casting of molten metals and, especially, to vacu 10 or ladle; and to make possible the development of new
and unique alloys as a result of the removal of inclusion
um casting of heavy forging ingots and the mass produc
forming materials.
tion of rolling ingots wherein gaseous components of
Another object of the invention is to devise a new
harmful nature are in part removed from the molten
combination of sealing compound and casting apparatus
metal during the period that the molten metal is being
for vacuum casting whereby unusual sealing effects may
be accomplished and also whereby the evacuation of air
poured into an ingot mold or ladle.
The invention, in one preferred form is directed espe
cially to treatment of molten steel in that state which
to produce a vacuum may be carried out in a highly con
is commonly referred to as “unskilled.” This term is
employed to distinguish a molten steel in which certain
venient manner.
contrasted with a molten steel in which gases have been
materials may be introduced into a body of molten metal
as it is being poured under vacuum to the end that there
may be induced reactions tending to further reduce th
Still another object of the invention is to provide a
gases are present in a relatively uncombined state as 20 method of vacuum casting in which chemically reactive
caused to combine with a material such as aluminum to
provide a so-called “killed” metal. It should be under
stood that the invention is not, however, limited to this
25
or any other particular application.
occurrence of harmful gases.
‘ '
A further object of the invention is to devise a method
operation is a more recent development of vacuum cast
of vacuum casting in which the percentages of reactive
alloying elements used in forming desired alloys of steel
ing and is employed primarily for the removal of hydro
may be modi?ed or controlled while a vacuum is in effect
ber necessarily comprises a heavy housing structure usual
after disclosed presents several unique techniques for
dealing with the problems outlined and accomplishing
the foregoing objectives with respect to various types of
Degassing of large forging ingots during the pouring
to provide desirable results.
gen from killed steels in order to diminish the suscepti
Another object is to control the degree of vacuum
bility of a steel to form internal hair-line ?ssures com~ 30
exerted as well as to modify vacuum conditions by furn
monly referred to as ?akes during cooling cycles to room
ishing an atmosphere of predetermined chemical nature
temperature from the hot working temperature.
which may be conducted through a region of pourin
Degassing is conventionally carried out at the present
and then evacuated.
'
time by utilizing a special vacuum chamber in which is
The method and apparatus of the invention herein
mounted an ingot mold or a ladle. This vacuum cham 35
ly made up of a top section and one or more lower sec
tions which can be secured together in sealed relation
ship in order to make these sections airtight. For seal
ing purposes, having regard for the high temperature
vacuum casting. These techniques are, in‘ preferred em
40 bodiments of the ‘invention, based on the concept of
conditions which exist in pouring molten metal, it is
creating a vacuum by evacuating gases through a side~
After a vacuum has been created in the housing struc
ture, hot metal is transported to a pony ladle located on
molten metal on any conventional sealing means which
the top of the chamber housing. As the hot metal is
poured into the pony ladle, the heat of the metal will,
thermal shock and expansion of the mold.
wall portion of a molten metal containing pouring box
customary to employ heavy rubber sealing rings. These
from which molten metal is to be poured, and supporting
rings are located in suitable sealing ?ange portions which
such a box in airtight relationship for a limited period
extend around outer peripheral surfaces of the sections
in protectively spaced relationship to hot metal passing 45 directly on an ingot mold. Thus, it becomes possible
to eliminate a separate vacuum chamber which has here
into the ingot mold during a pouring operation, Water
tofore conventionally enclosed the ingot mold and several
cooling may be employed in some cases.
other novel techniques are‘rendered feasible.
In a conventional structure of this class, the top sec
In this connection, it will be appreciated that an im
tion of the vacuum chamber is provided with a pouring
aperture which is normally closed by a fusible diaphragm. 50 mediate obstacle to holding a box and mold member in
sealed relation is the high temperature effect of the
is capable of producing an airtight joint including the
I have discovered that a high vacuum seal may be
after a short interval, melt the diaphragm and the molten 55
produced and maintained for a short interval by a new
metal falls into the chamber. The vacuum within the
technique which may be conveniently referred to as
chamber operates to disperse the metal into molten drop
“Transient Thermal Sealing.” This technique may, I
lets and to remove gases such as hydrogen and limited
?nd, be accomplished by the use of special sealing means
amounts of oxygen and nitrogen.
It.is found that establishing a satisfactory vacuum 60 including a novel sealing compound which has the ability
to temporarily resist ?owing or decomposing from rela
with such a form of vacuum casting apparatus is a costly
and careful manipulation to maintain a satisfactorily high
tively intense heat conducted through the metal body
portions of the pouring box and mold during the time
in an operative position for the production of large forg
ing ingots or small rolling ingots and readily disengaged
matter comprising a mixture of three essential com
and complex procedure requiring expensive equipment
interval which corresponds to the short period in which
vacuum. The vacuum must be capable of being held in
the presence of very high temperatures, either for short 65 molten metal is passing from the pouring box to the
ingot mold.
or long periods, and the equipment should be of such
As an example of one sealing means which is suitable
construction that it may be simply and quickly spaced
when not in use.
Existing equipment does not meet
for this purpose, I may employ a new composition of
ponents—(I) a low molecular weight glycidyl polyether,
these requirements. It is also pointed out that, if it
(II) a condensation product of a low molecular weight
becomes necessary to vacuum pour more than one ingot
glycidyl polyether and ethylene glycol and ('III) a curing
3,024,507
3
4
agent composed of pyromellitic dianhydride mixed with
more apparent from the following description of preferred
the anhydride of a dicarboxylic acid. When these com
ponents are combined in the hereinafter described pro
portions a resinous mixture is obtained which upon ex
posure to heat at elevated temperatures resists melting and
cures to a solidi?ed adherent elastic body. In addition to
the above ingredients it may be desirable to include var
ious ?llers and a cure accelerating agent.
The composition of matter noted above is intended to
embodiments of the method and apparatus as shown in
the accompanying drawings, in which:
FIG. 1 is a side elevational view illustrating diagram
matically casting apparatus as employed in the inven
tion;
FIG. 2 is a detail plan view;
FIG. 3 is a vertical cross-sectional view of the vacuum
casting apparatus of the invention as it appears when re
be representative of sealing compound means which is 10 ceiving molten metal; and
FIG. 4 is a detail cross sectional view of a modi?ed
sufficiently ?uid to “wet” and adhere to metal surfaces of
sealing arrangement.
casting members; which is characterized by the ability to
Referring more in detail to these ?gures, numeral 2
cure when brought into contact with metal surfaces heated
to temperatures of from 250~500° F. to form a tough
elastic adhesive; and which in this cured state is capable
of resisting ?owing or melting in the presence of much
greater temperatures, i.e. 500—l000° F. for a limited
denotes an ingot mold 2 of the invention having an ingot
cavity 4 which tapers downwardly, as shown in FIG. 1.
This mold member is preferably seated on a heavy ?at
bottom stool 6.
At its upper side, the ingot mold is formed with a flat
seating surface 8 which extends around the ingot cavity
period of time corresponding approximately to an ingot
pouring interval.
In combining the sealing compound described with a 20 4 to provide a support for a removable pouring box mem
ber, generally indicated by the arrow 10.
molten metal containing box in airtight relationship with
In accordance with the invention, I have devised as
an ingot mold, in accordance with the invention, there
component parts of this pouring box 10 an upper metal
is, in effect, produced an exceedingly high vacuum sealed
containing section 10a and a lower conduits section 10b.
conduit through which molten metal may be conducted
from the basket to the ingot mold.
25 These box sections are separated by a transverse wall 100
through the center of which is formed a pouring aperture
By the expression “exceedingly high vacuum,” I refer
12 which is normally closed by a fusible closure cap 14
to micron guage readings of an outer magnitude of as
low as four (4) microns at the point where the vacuum
of aluminum or other suitable material.
The cap 14 is
secured by bolts as ‘16 and 18. In the presence of hot
pumping means “blanks off.” This micron reading is in
contrast to optimum micron readings possible with con 30 metal discharged from a transporting ladle 22, shown at
the upper side of FIG. 1, the closure member 14 becomes
ventional equipment of from 300-500 microns.
fused and will then allow the hot metal to ?ow through
I further ?nd that I may exert this exceedingly high
the aperture 12 and then through the conduit section 10b
vacuum at the conduit region in close proximity to the
to ?nally be received in the mold cavity 4.
stream of molten metal which is poured from the basket
The lower conduit section 1% also receives an an
and also in close proximity to the metal collecting in the 35
nular refractory “hot top” 19 which is necessary on all
ingot mold to produce unexpected results of great sig~
killed steels. The refractory 19 must be thoroughly
ni?cance. The high vacuum, when thus exerted, not only
heated and dried before placing on the vacuum mold. Of
disrupts and disperses the molten stream of metal in the
form of a spray of ?ne particles, but also causes this
importance to the success of the invention is the seal 20
metal, as it collects in the mold, to be vigorously agitated
between the hot top and mold. The best seal to prevent
the ?ow of steel between the mold and hot top is tamped
steel wool. Wet refractory cements give off water and
gas which makes trouble. Back pouring is the practice
and to ebullate in a particular manner wherein portions
of collected material continuously rise up around the
inner surfaces of the ingot mold and fall over into the
for open atmosphere pouring.
central portions of the mass.
I further construct the box 10 with means for evacuat'
I have further discovered that, by exerting a vacuum in
ing gases through the conduit section 10b, as indicated in
the manner described, I am enabled to greatly increase
FIG. 1. The evacuating means includes a passageway
the removal of harmful gases and to modify the per
formed through the sidewall portion of the conduit sec‘
centage of alloying additive which may be retained in the
steel. It is believed that the combined effect of removing
tion, as shown, and into which is tightly ?tted a tubular
gases as the stream is dispersed in the conduit region and 50 member 26. Attached at some convenient point to the
outer end of the tubular member 26 is a vacuum pump
also removing gases which are thrown up by the con
unit 29 of some conventional nature.
tinuous ebullience produced is the reason for this im
proved vacuumizing, although this is stated by way of
When the box 10 is arranged in the seated position
opinion only.
shown in FIG. 1 and the vacuum pump 29 is started, air
will be evacuated from the conduit section and the ingot
I have further discovered that I may introduce reacting
cavity and a vacuum will be created when the high vac
materials directly into the conduit region Where the
uum type seal of the invention is exerted between the
molten metal leaves the box and where some degassing
pouring box and the mold. The effectiveness of my seal
takes place. I ?nd that by bringing reactive materials in
is indicated by the degree of vacuum attained. Normally
a suitable dispersed state into the conduit region and
simultaneously dispersing the molten metal into minute 60 I ?nd an absolute pressure of forty microns is reached
droplets in the presence of these dispersed reactive mate
in about two minutes, and twenty microns in about four
minutes. Pressures below ten microns are consistently
rials, there may be carried out desirable chemical reac
tions in both the dispersed and collected material which
reached in ten minutes. The lowest pressure developed
reactions bene?cially use up small quantities of harmful
has been four microns. Speed of pump down is extremely
gases. Resultant reaction products are rapidly carried off 65 critical in pouring a series of molds. Time delays cause
through the vacuum equipment. I may also introduce
temperature losses in the molten metal and solidi?cation
alloying additives into the stream of molten metal as it
or skulls in the ladle or box.
Another important feature of the invention is the
is poured under vacuum, either during or after the use of
method of so-called transient thermal sealing in which
reactive materials.
A further novel feature of this step of adding a mate 70 the sealing compound earlier noted is applied at the junc
rial at the particular period indicated consists in the fact
that substantially all of an alloying additive may be thus
tion of the relatively hot seating surface 8 of mold 2.
As utilized in the invention the sealing compound is em
introduced and caused to serve its intended alloying pur
ployed in a substantially ?uid condition so that it may
poses without undesirable side reactions taking place.
be applied to the metal surfaces of the box and mold and
These and other novel features and objects will be 75 will wet and adhere to these surfaces and penetrate
3,024,507
O
the pouring box resting on the mold surface 8 and, in
the value of “n” decreasing as the quantity of epichloro
hydrin is increased.
Considering for purposes of illustration the most widely
ordinary working conditions, the mold and box under
usual foundry conditions will be at temperatures of from
employed dihydric phenol, bis (4-hydroxy phenyl) di
methyl methane (hereinafter termed Bisphenol A) the
200° F. to 500° F.
dinlycidyl ether has the formula:
slightly into the pores of the metal surfaces. It will be
understood that the sealing compound is applied with
In FIG. 1, I have indicated the sealing body applied in
one desirable form on the mold and box and denoted by
the numeral 30.
As is further shown in FIG. 3, the
sealing compound occurs as an irregular mass of mate
10
rial which ?lls in around the outer line of junction of the
mold and box in such a position that, while it effectively
seals this region, it is, nevertheless, protected by the thick
where n of Formula 1 is zero.
By employing a mole
ratio of epichlorohydrin to Bisphenol A of 10:1 the di
glycidyl ether is produced in a fairly pure state. As the
the mold itself.
mole ratio is decreased the proportion of higher molecular
I have also discovered that the use of a sealing com
weight polyethers increases. In general, mole ratios of
pound such, for example, as that indicated by the com
2:1 to 10:1 give average molecular weights of about
pound 30, may be very desirably carried out by utilizing
350 to 450. In practice it is found that though the size
specially formed surfaces at the portion of the mold
which supports the pouring box. For example, as illus 20 of the major portion of the polyether molecules may be
controlled, some small proportion of longer and shorter
trated in FIG. 4, I may form a mold body 2a with a
length molecules will be present. In addition side reac
recessed portion 21), constituting in effect an annular
tions may occur with some formation of intermediates,
groove extending all the way around the mold body 2a.
but the quantity of these side products does not notice
This groove is of a radial width substantially exceeding
ably in?uence the properties of the resin.
the thickness of a pouring box section 10g. In this groove
In preparing the sealing compound 30 I produce com
I locate a body of sealing compound 30a, which com
ponent I, the low molecular weight glycidyl ether by
pletely ?lls the groove so that the pouring box section
using as a dihydric phenol, bis (4-hydroxy phenyl) di~
10g is embedded in the sealing compound and substantial
methyl methane, having an average molecular weight of
portions of the body of sealing compound are present at
from 350 to 450. With other dihydric phenols this
both the inner surface 10f and the outer surface 10k. A
range will vary slightly. Referring to Formula 1 the
second heat resistant sealing body is employed at the base
average molecule of the ether will contain between 1
of the mold, as indicated by reference character 10m in
and 1.5 R's (aromatic radicals) and “n” will vary from
FIG. 3, and between the mold body and the ?at bottom
0 to. l. The epoxide equivalent (weight of resin in grams
stool 6.
containing 1 gram equivalent of epoxy) should be be
The purpose of this arrangement is to deal with and
tween about 175 and 225. Assuming the resin chains
compensate for, the abrupt thermal expansion and con
to be substantially linear with an epoxy group terminat
traction of the mold and box which takes place during
ing each end, then the epoxide equivalent is One-half the
the pouring of the molten metal. The sudden change in
average molecular weight. The viscosity of the poly
temperature may, I ?nd, produce a rapid stress amounting
ness of the box wall section as well as the thickness of
to a thermal shock which, in some cases, operates to 40 ether will vary from 5,000 to 20,000 c.p.s. as measured
break down and render useless sealing means which have
been tried in earlier efforts in the art to hold a seal. In
the arrangement of a seat of the invention, the compound
being of a compressible somewhat elastic nature, is com
with a Brook?eld LVT-SX viscometer with No. 5 spindle
at 6 rpm. at 25° C. Many commercially available
epoxy resins with suitable properties may be used.
Among these are “Bakelite ERL-2774” and “Bakelite
preserve a sealing effect on one side of the box even
Co., Div. of Devoe & Reynolds Co.; “Epon” is the trade
pressed at one side of the other of the box 10g with the 45 ERL-3794,” “Epi-Rez 510,” “Epon 820” and “Epon
828.” “Bakelite” is the trademark of Union Carbide
compound being squeezed between this member and an
Corp; “Epi-Rez” is the trademark of the Jones-Dabney
adjacent groove surface of the mold. This operates to
'
though the seal is broken on the other side when the ex 50 mark of the Shell Chemical Corp.
Component II is the reaction product of component I
pansion occurs. In thus combining both an inner and
with a glycol, for example, ethylene glycol. The ratio of
outer sealing means with the inner and outer surfaces of
epoxy to hydroxy can be varied from l/0.5 to 1/2 with
the pouring box, a desirable cooperative effect is present
little effect on the ?nished compound. The reaction may
by utilizing the refractory material 19 and the steel wool
backing 20 to shield the sealing compound to a limited
but desirable extent.
The sealing compound 30 is of the class of compounds
containing in general polyepoxide materials. Epoxy
be carried out by mixing the desired quantities of epoxy
and ethylene glycol and heating to 150° to 185° C. for
1 hour or until the mixture becomes homogeneous.
The product has a molecular weight of 385 to 485 and
is believed to consist primarily of the product resulting
resins are prepared by the reaction of a dihydric phenol
and epichlorohydrin in the presence of sufficient alkali 60 from the reaction of one epoxide ring with an hydroxyl
group of the glycol. Since component I can be consid
to maintain the reaction mixture substantially neutral.
ered to contain an average of two epoxy groups per
The predominant constituent of the reaction product
is represented by the formula:
molecule, it is quite certain that the primary condensation
(1) 0
O
OH
wherein R represents a divalent aromatic hydrocarbon
radical and “n” is an integer. By varying the ratio .of
epichlorohydrin to the dihydric phenol, compositions of
varying molecular weight (varying “n”) may be obtained,
product resulting from such controlled conditions may be
represented by the formula:
8
For convenience I shall refer to the condensation prod
uct as the 50% condensate of component I with a glycol.
Component II lends ?exibility to my resin composition,
but must be used in controlled amounts.
I have found
empirically that the ratio of component I to component
II may vary from
20 E
E 1'. o as
nent I and ethylene glycol in the previously described
ratios. It has the following properties:
Viscosity ______________________ _.
Speci?c gravity _________________ _.
Color ________________________ __
Epoxide equivalent _____________ _.
550 cps. at 25°C.
1.14.
2 (Gardner Scale).
385.
Hydrolyzable Cl _______________ _. 0.15%.
Twelve parts of component I was blended with 88 parts
with good results. When the quantity of component II 10 of component II and 43 parts of phthalic anhydride and
passed through a colloid mill to reduce the particle size
is more than 88 parts, the resin after curing is gel-like
of the phthalic anhydride to 0.025 mm. or less. Care
and weak. When the amount of component II is less
must be maintained to keep the temperature below about
than 80 parts, the composition cures to a brittle, easily
50° C. during passage through the mill. After cooling to
cracked material.
The third component (III) of my composition is a 15 room temperature 2.5 parts of pyromellitic dianhydride
was added together with 55 parts of micronized silica, 35
curing agent which acts to cross-link the epoxy com
parts of atomized aluminum, and 350 parts of short ?ber
pounds. The curing agent which I prefer to use is a mix
asbestos. The mixture was thoroughly blended while
ture of a primary curing agent, pyromellitic dianhydride,
maintaining the temperature of the mix below about 25°
and a secondary curing agent selected from the group of
organic acid anhydrides. The anhydride mixture is used 20 C. and 0.3 part of pyridine were added to the mixture to
act as a cure accelerator. The composition was applied
in stoichiometric quantities based on the amount of epoxy
to two steel rods about 2.5 cm. by 1.25 cm. by 30 cm.
and hydroxyl groups present in the resin mixture. A
and the steel rods were pressed together end to end.
slight excess, about 5%, is employed in the case of solid
These rods were heated to 205° C. for 15 minutes to cure
acid anhydrides to allow for uneven dispersion of the an
hydride powders in the resin.
25 the composition. The rods were then raised to 315° C.,
allowed to cool to room temperature and heated again
Anhydrides of dicarboxylic acids are well known in the
to 345° C. The resin bond remained strong with no
art as curing agents and include phtalic anhydride, maleic
cracks or thermal decomposition noticeable.
anhydride, succinic anhydride, dodecenylsuccinic anhy
As a further test of the ability of the composition of
dride, and hexahydrophthalic anhydride.
Depending upon the particular anhydride curing agent 30 Example I to withstand high temperatures, a sample of
the composition which had been cured at 205° C. for
used, the proportions of primary and secondary curing
15 minutes was placed in contact with a surface at 315°
agents in component III may be varied within certain well
C. for a period of eight hours. There was no evidence of
de?ned limits. I have found that 2 to 15 parts of pyro
serious charring or decomposition, and the sample re
mellitic dianhydride and 42 to 17 parts of secondary an
hydride for every 100 parts of resin give satisfactory seal 35 tained its normal compressibility.
ing materials for high temperature uses.
The manner in which component III is added to the
Example II
Component I was prepared in the manner described in
epoxy compositions will depend upon the particular an
US. Patent No. 2,682,515, column 6 under the heading
hydrides in component III. Phthalic anhydride must
ordinarily be passed with the resin through a colloidal 40 “Polyether A.”
Component H was prepared by adding 46.5 grams of
mill to get a good dispersion. Maleic anhydride, on the
ethylene glycol to 180 grams of component I. The re
other hand, is sut?ciently ?ne to be mixed in by hand.
action mixture was maintained at 150° C. for 1 hour.
When it is desired to shorten the curing time, various
Upon cooling there resulted a clear, low viscosity mono
well-known cure accelerators may be added to the com
position. Among these are alphamethylbenzyl dimethyl 45 functional-epoxy ?exibilizer.
amine, n-butyl amine, pyridine and N-methyl pyridine.
These are used in catalytic amounts, from 0.5 to 3% of
the weight of the resins in the composition.
Sixteen parts of component I was mixed with 84 parts
of component II and blended well at 25° C. To the mix
was added 13.8 parts of pyromellitic dianhydride, 19.4
parts of maleic anhydride, 75 parts of micronized silica,
In addition to the above basic ingredients it is advan
tageous to add various ?llers to the composition to add 50 25 parts of atomized iron, and 150 parts of short ?ber
asbestos. After mixing well a homogeneous blend of
body, adjust viscosity, increase thermal conductivity and
milk-like consistency was produced. To this was added
hence achieve more even cure and lower the coe?icient
0.4 part of N-methyl pyridine to act as a cure accelerator.
of the thermal expansion. Among the ?llers which can
The composition was spread on steel rods and baked
be used are atomized aluminum, iron, copper, aluminum
oxide, silica powder, mica, and asbestos. Fibrous ma 55 for 20 minutes at 175° C. After carrying out the heat
ing and cooling steps of Example I, the ‘bond was found
terials such as ?ne asbestos tend to bind the resin to
to retain its strength.
gether and counteract differences in thermal expansion
Though in the foregoing examples component II was
between the resin and the bonded metal. The quantity
in each case a condensate of component I and ethylene
of ?ller may be varied from a few percent to three or
four times the weight of the resin. The compounding 60 glycol, this need not be the case. Component II of Exam
ple I could have been substituted for component II of
manipulations are well-known to those skilled in the art.
Example II and vice versa. It is only necessary that
The following examples illustrate the preparation of
component II be approximately a 50% condensate of a
the compositions of my invention.
glycol and a glycidyl polyether epoxy resin having a mo
Example I
65 lecular weight between about 350 and 450, an epoxide
A commercial epoxy resin, “Epi-Rez 510" with the fol
lowing properties was employed as component I:
Viscosity ______________________ _. 12,000 cps. at 25° C
Speci?c gravity ________________ __ 1.15.
Color ________________________ __ 3 (Gardner Scale).
Epoxide equivalent _____________ __ 185.
equivalent of 175-225, between 1 and 1.5 aromatic radi
cals per polyether chain and a viscosity between 5,000 and
20,000 cps.
‘Also, though I have shown component I to be made
70 from Bisphenol A and epichlorohydrin for purposes of
illustration, other dihydric phenols are suitable. These
include resorcinol; 1, l-bis (4-hydroxphenyl) ethane; 1,
l-bis (4-hydroxyphenyl) propane; l, 1~bis (4-hydroxy
phenyl) butane; 2, 2-bis (4-hydroxyphenyl) butane and l,
Component II is also a commercial epoxy resin, “Epi
Rez 507” which is the condensation product of compo 75 l-bis (4-hydroxyphenyl) 2-methyl propane.
Hydrolyzable Cl _______________ __ 0.1%.
‘3,024,507
9
10
In operation, the mold and basket are assembled as
shown and air is evacuated from the mold cavity and con
duce alloying additions into the molten metal as it passes
through the conduit section into the ingot mold. As
shown in FIG. 2, I may provide for this purpose a second
tubular member 36 having a feed inlet suitably closed
when not in use and through which additives may be
passed. This tubular member is connected into the con
duit section to provide a suitable vacuum. This vacuum
is maintained in effect and hot metal M of the unkilled
class referred to above is poured into the metal containing
section 10a from the ladle 22. The heat of this molten
duit section wall and may also include at its outer end a
metal melts the closure member 14 and the molten metal
viewing piece 39. This viewing piece 39 enables an op
starts to ?ow through the passageway 12. As the hot
erator to observe conditions at the point where the metal
metal enters the degassing chamber 20, it is instantly sub
jected to disruptive forces produced by the vacuum de 10 is subjected to vacuum and dispersed and also permits a
limited view of portions of the mold cavity.
scribed and the stream of entering metal is separated
It is pointed out that, by means of this arrangement,
into a multiplicity of small metal droplets.
reactive materials which produce oxides or sulphides may
In this dispersed droplet state, gases such as hydrogen,
have their reaction products removed by vacuum. By in~
nitrogen and oxygen, in the form of carbon monoxide,
are drawn off by the vacuum forces. At the same time, 15 troducing material in the manner noted, there is an op
portunity for the additives to combine with materials in
the molten metal, as it collects in the ingot mold, is caused
the molten metal producing objectionable gases which are
to continuously ebbulate and, in the course of this agita
carried off in the vacuum stream. One chemically reac~
tion, a further additional and important removal of
tive material which I may add consists of “misch-metal”
gases takes place and especially there may be removed
small quantities of carbon monoxide. The percent of 20 which acts to combine with sulphur in deoxidizing metal.
Other materials which may be added for the purpose of
gases in the metal may, I ?nd, be desirably reduced in
alloying include titanium, vanadium, chromium and the
both of these ways, i.e., from the dispersed material and
like. It will be observed that, in thus introducing an
the collected material, and a highly signi?cant reduction
alloying additive such as noted, there is found an op
in carbon content may occur when the initial carbon con
tent is low. This removal of carbon monoxide serves 25 portunity to ?rst remove undesirable substances present
both as a deoxidation treatment for high carbon steels
in the molten metal as it is poured and then the alloy
and as a decarburization treatment and deoxidation treat
ment for very low carbon content steels.
ing additive may be dropped into the mass at a time when
it can be most effectively employed.
From the above disclosure, it will be evident that I have
discovered a new and desirable method of degassing
In accordance with a further important feature of the
invention, I provide for further removal of gases for a
which may also be carried out in conjunction with adding
short period after the actual pouring operation has termi
nated. I accomplish this novel step by introducing into
reactive materials as well as alloying additives. By means
of these procedures, it is possible to produce better alloys
the basket 10 special closure means for sealing the pour
ing aperture 12 from the upper side thereof at a point just
of known type, as well as some new alloys.
before the last portion of molten metal leaves the basket 35
so that the vacuum is either maintained or renewed and a
It is pointed out that, by means of this vacuum sealing
means described, it becomes possible to carry a highly
simpli?ed and efficient vacuum casting operation with
saving in cost of handling, time consumed and equipment
used. The two principal components are readily assem
type now exceedingly difficult to produce by conventional 40 bled and just as readily separated from one another when
secondary degassing takes place.
I ?nd that, by means of this secondary or extended
vacuumizing, I may produce a very low carbon steel of a
desired.
It is pointed out that, with the vacuum effect
furnace practice. For example, I may provide for a car
bon content as low as .05 and lower, as will be evident
exerted through the basket, there is eliminated the need
from an inspection of the following table.
of a special housing to form a vacuum chamber and, yet,
a high efficiency may be realized.
Vacuum
Material
Convention-
Casting by
al Casting
thetlnven
ion
While I have disclosed preferred embodiments of the
invention, it will be understood that various modi?ca
tions may be practiced within the scope of the appended
claims.
This application is a continuation, in part, of my co
pending application, Serial No. 656,228, ?led May 1, 1957
now abandoned.
Unkilled 10% 0. Steel __________________ __
Having thus described my invention, what I claim is:
1. In a method of vacuum casting the steps which
Unkilled 20% 0. Steel __________________ __ I
.
C
Killed 12% Cr. Steel ____________________ __ 066% Nz_-__
13% 0.
039% N2
.()l2% AL." 01% Al
30% C .... __
% C.
Killed Cr-Ni-Mo Steel __________________ _- 027% N2____ 027% N2.
042% Al. ___ .037% Al.
include positioning an uncured plastic ?owable sealing
material between the surface of a cast iron casting mold
and the surface of a vacuum chamber having an upper
sealable opening supported on the mold, subjecting the
sealing material to heat conducted through the casting
mold to provide a cured solid, elastic vacuum tight seal
60 ing mass extending around the line of junction of the
casting mold and chamber conforming to the surfaces
thereof, sealing said vacuum chamber and evacuating
air from the chamber to provide a high vacuum, ?owing
molten metal through said upper sealable opening and
through the evacuated chamber into the casting mold
while simultaneously maintaining the sealing mass in seal
ing relationship between said surfaces for a period at
accomplished. This usually requires about twenty min
least as long as the ?owing interval, and subjecting said
utes after all of the metal has passed into the mold. This
sealing mass to heat of increasing intensity which is
also allows su?icient time for the solution of any alloy
additions. At this point, the heat ?ow reaches an inten 70 transmitted from the molten metal through the casting
mold to said sealing mass, said sealing relationship of
sity causing the compound to decompose and become
said mass between said surfaces thereafter being destroyed.
charred or volatilized.
The period during which a required amount of metal
suitable for ?lling the ingot mold will flow is of limited
duration. In this short time interval, the heat which ?ows
toward the sealing compound 30 does not reach a maxi
mum intensity until the desired vacuumizing has been
In addition to removal of gases by connecting a vacu
2. A method as claimed in claim 1, wherein said
mold is provided with a continuous well extending around
to realize other advantages. For example, I may intro 75 said line of junction for receiving said surface of said
um member into the conduit section, I am also enabled
3,024,507
11
12
vacuum chamber, with said sealing material being posi
tioned in said well against said surfaces.
References Cited in the ?le of this patent
UNITED STATES PATENTS
3. A method according to claim 1 in which the heat
resistant sealing mass includes a low molecular weight
glycidyl polyether, a condensation product of a low mo 5
lecular weight glycidyl polyether and ethylene glycol and
a curing agent.
4. A method according to claim 1 in which the heat
resistant sealing mass includes a low molecular weight
glycidyl polyether, a condensation product of a low mo 10
lecular weight glycidyl polyether and ethylene glycol and
a curing agent composed of pyrometllitic dianhydride
mixed with the anhydride of a dicarboxylic acid selected
from the group consisting of phthalic anhydride, maleic
anhydride, succinic anhydride, dodecenylsuccinic anhy
drided, and hexahydrophthalic anhydride.
5. A method ‘according to claim 1 wherein the de
struction of said sealing relationship is caused by thermal
decomposition of said sealing mass.
2,140,607
Thompson ____________ __ Dec. 20, 1938
2,187,594
2,197,259
2,734,241
2,851,375
2,885,751
Wean ________________ __ Jan. 16, 1940
Nead ________________ __ Apr. 16, 1940
Samuel ______________ __ Sept. 9, 1958
Hornak ______________ .. May 12, 1959
339,721
866,231
Great Britain _________ __ Dec. 18, 1930
Germany _____________ __ Feb. 9, 1953
797,973
Great Britain __________ __ July 9, 1958
Southern ____________ __ Feb. 14, 1956
FOREIGN PATENTS
OTHER REFERENCES
Epoxy Resins their Application and Technology by
Henry Lee Kriss Nelville (1057), pages 260~270 relied
upon.
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