Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS AND APPARATUS FOR CASTING
ROUNDS, SLABS, AND THE LIKE
Technical Field
This invention relates to a process and apparatus
for casting rounds, slabs, and the like from high melting
point metals and is particularly concerned with the direct
easting of semi-finished steel products.
Backqround Art
The conventional way to manufacture "semi-finished"
steel products, such as rounds, slabs, blooms, and billets,
is to pour molten steel into an ingot and then roll the ingot
down into a roun~d, slab, bloom, or billet in a rolling mill.
The semi-finished products are then made into bars, tubes,
sheet, strip, or the like, which are called "finished prod-
uct~
It may require up to twenty-five or more passes
through various rolling mills to;transform an ingvt into a
semi-finished product. The reduetion in cross-sectional area
from an ingot to a semi-finished product is at least four to
one. A great deal of energy, as well as expensive capital
equipment, is thus requi~red to reduce the ingot to semi-
finished produet forms.
A more modern technique for making slabs and other
semi-finished products is the continuous casting process
whereby molten steel is poured into a tundish, from there ~-
into bottomle~s, cooled vertical molds, and then withdrawn by
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rolls or other mechanisms in a continuous length. Pieces are
cut off from this continuous length to give slabs, blooms, or
billets as desired, in accordance with the shape of the ver-
tical mold. Although deceptively simple in principle, this
technique has, in practice, many inherent difficulties. Con-
tinuous casting equipment is bulky and requires a large
amount of space for each installation. The capital invest-
ment is enormous, and the process is not suitable for low
volume production.
Although slabs and billets can be cast by the con-
tinuous casting process, the casting of rounds by continuous
casting has not proved satisfactory because rounds have the
least surface area per unit of volume and are difficult to
cool and otherwise handle in a satisfactory manner in a con-
tinuous casting process.
Another technique for making slabs, particularly
stainless steel slabs, is the bottom pressure pouring method
described in my U. S. Patent No. 3,196,503. According to
this technique, a ladle filled with molten steel is placed in
a pressure vessel which is sealed with a lid. ~ pouring tube
extends through the lid down to within approximately 4 to 6
inches (10 to 15 cm) from the bottom of the ladle. The top
part of the pouring tube is mechanically connected to the
filling end o the slab casting mold. Air pressure within
the vessel causes the molten steel to rise through the pour-
ing tube and enter the slab mold at the lower end, the mold
being at a slight tilt~ The equipment is expensive, and
there are problems with inclusions; since the top portion of
the slab to which inclusions normally rise is the first por-
tion to become cool.
It is well known that ferrous metals can be cast
directly into commercial products in sand molds. It has not,
however, generally been possible to cast them directly into
commercial products in a permanent mold because the molten
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ferrous metal welds to and/or erodes the sidew~lls of the mold
and, if there is any vertical drop, the forces of the falling
molten metal cam damage, or even knock out, the bottom of the mold.
Disclosure of Invention
An object of the present invention is to provide a
new and useful process for the direct casting of semi-finished
steel products and similar products of other high-melting-point
metals, particularly rounds and slabs.
Another object of the present invention is to provide an
efficient and inexpensive process and apparatus for the direct
casting of semi-finished products which have low levels of impuri-
ties and superior grain structure and surface characteristics.
In accordance with one aspect of the prese~t invention
there is provided a process of directly casting semi-finished
products of a high-melting-point metal with constant cross
sections in a permanent metal mold which has smooth sidewalls
which form a casting cavity with a cross section corresponding to
that of the products to be cast, comprising the steps of:
(a) disposing in the top portion of the casting cavity
20 a plunger about the circumference of which is a thin resilient ~:
metal band which extends above the top of the plunger and maintains
sliding and sealing contact with the sidewalls of the mold, the
metal band being attached to the plunger, a barrier to the molten
high-melting-point metal being on top of the plunger inside of
the metal band;
(b) providing a reservoir for the molten metal above
the plunger;
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(c) pouring molten metal of a high melting point into
the reservoir;
(d) as soon as the reservoir is substantially full,
causing the plunger to descend relative to the mold toward the
bottom of the cavity at a control rate of from 1/2 to 4 inhes per
second while keeping the reservoir supplied with molten metal,
thereby causing molten metal to enter and fill the space being
created in the cavity above the plunger as it descends;
(e) promptly after the plunger has completed its
descent, applying enough lifting force to the plunger relative to
the mold to break any adhesions with the sidewalls of the mold and
prevent hanger cracks while maintaining the reservoir in
communication with the casting;
(f) allowing the casting to cool and further solidify
enough to be handled; and
(g) stripping the cast product from the mold.
Accordiny to another aspect of the invention there is
provided an apparatus for directly casting semi-finished products
of a high-melting-point metal with constant cross sections which
comprises:
(a) a steel mold with smooth,~vertical sidewalls which
define a casting cavity having a constant cross section which
corresponds to the cross section of the product to be cast;
~b) a plunger adapted to be lowered and raised in the ~ .
casting cavity, the plunger having a cross section which is about
the same as but slightly smaller than that of the casting cavity; ~-
(c) a metal band attached to the plunger with a thin, -.
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resilient upstanding portion which extends substantially above
the top of the plunger and is held against the vertical sid~lalls
of the mold to make a sllding seal -therewith;
(d) means on the top of the plunger inside of and
below the top of the upstanding portion of the metal band for
acting as a barrier to the molten hiyh-melting-point metal and for
insulating the plunger from the molten metal so that a minimum
amount of heat is drawn from the molten metal by the plunger;
(e) a reservoir for molten high-melting-point metal on
the top of the mold over the casting cavity for supplying molten
metal to the space being created over the plunger;and
(f) means for lowering and raising the plunger
relative to the mold.
According to a further aspect of the invention there is
provided an apparatus for casting rounds directly from molten, high-
melting-point metal which comprises:
(a) a tubular steel cylinder with a smooth inside
cylindrical surface defining the casting cavity mounted vertically
on a supporting platen, the weight of the cylinder being at least
1-I~2 times the weight of the round to be cast;
(b) a cylindrical plunger adapted to be lowered and
raised in the casting cavity;
tc) a thin, resilient steel band with an upstanding
portion placed against the inside surface of the casting cavity
above the top of the plunger, the band being attached to the plunger,
the upstanding portion of the band extending at least 1-1/2 inches
above the top of the plunger;
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(d) a refractory layer on top of the plunger inside
the steel band;
(e) means for loweriny and raisiny the plunger; and
(f) a reservoir for molten metal on top of the tubular
steel cylinder~
The plunger is preferably lowered and raised by a
screw jack driven by an air motor.
r~he mo]ds for rounds are preferably made of inner and
outer steel sleeves which are separated by a layer of sand. The
molds for slabs and other flat products are preferably made of
side blocks and slotted steel and blocks which are reinforced with
strongbacks. The molds can be reused many times and can be adapted
to pour single rounds or slabs, or multiple rounds or slabs, or
the like, as desired.
The present invention thus provides a process and
apparatus for casting ferrous and other high melting point
metals directly into rounds, slabs, and other semi-finished
products in relatively inexpensive equipment with low production
costs and hi~h production rates, maximizes the yield from the
molten metal being poured, minimizes the losses, and produces
semi-finished products with improved surface quality and grain
structure.
Using the present invention, slabs may be made without
utilizing additional energy to reheat the steel or ingot
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such as is necessary to operate a rolling mill, thus conserv-
ing energy and saving substantial expense. The present in-
vention is especially adaptable to the production of cast
products in relatively small volumes, such as the production
of stainless steel products, where continuous casting could
not be employed because of the large output necessary and
lack of flexibility.
The present invention provides cast products of
excellent quality. The molten metal passes into a mold with
minimal contact with air, so that oxidation of the metal is
minimized. The quality of the surface of the product is
improved because the upward force from the plunger on the
casting minimizes the air gap between the casting and the
mold and reduces areas of adhesion. Splashes, buckles,
wrinkles, and cold shots are eliminated because the metal
does not drop any substantial distance. Inclusions rise to
the top of the cast product and are easily cropped off. The
flow of metal by gravity follows the natural convection pat-
terns of the system, in contrast to the flow patterns pro-
duced in bottom pressure casting, because in the present
invention the hot metal is fed into the top of the mold and
the hot metal rises to the top of the mold.
The process and apparatus of this invention may be
used to cast products from any of the ferrous metals includ-
ing stainless steel and from other high-melting-point ~etals,
such as ni~kel, c~ppel, and tltaniu~.
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Brief Description of Drawinqs
FIG. 1 is a side elevational view, in section, of a
mold for casting rounds using the process and apparat~s of
the invention;
EIG. 2 is an enlarged, side sectional view of the
plunger of FIG. l;
FIG. 3 is a top plan view, partially in section, of
the plunger and top of the mold, taken along line 3-3 of FIG.
FIG. 4 is a side sectional view similar to FIG. 1,
illustrating the casting process for rounds with the plunger
about halfway down;
FIG. 5 is a side sectional view similar to FIG. 4
showing the plunger all the way down and the mold cavity
filled with molten metal;
FIG. 6 is a side sectional view similar to FIGS. 4
and 5 showing the cast round and pouring cup lifted slightly
from the mold as the cast round cools;
FIG. 7 is a plan view of the shim band showing the
slits which facilitate wrapping it about the circumference of
the retaining plate.
FIG. 8 is an enlarged side sectional view of a mold
showing another embodiment of this invention for casting hol-
low rounds;
FIG. 9 is an end elevationaI view, with portions in
section, of a mold showing another embodiment of this inven-
tion for casting a single slab;
FIG. 10 is a top plan view of the single slab mold
of FIG. 9;
FIG. 11 is a side sectional view of the single slab
mold taken along line 11-11 of FIG. 9:
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FIG. 12 is an enlarged top plan view of a portion of
the pouring cup and plunger for the single slab mold of FIG.
9; `,
FIG. 13 is an enlarged side elevational view of a
portion of the pouring cup and plunger for the single slab
mold of FIG. 9, taken along line 13-13 of FIG. 12;
FIG. 14 is an end elevational view of a portion of
the pouring cup and plunger for the single slab mold of FIG.
9, taken along line 14-14 of FIG. 13;
FIG. 15 is a plan view of the screw jack motors and
air supply system for the plungers of the single slab mold of
FIG~ 9; and
FIG. 16 is a series of perspective views, illustrat-
ing some of the semi-finished products which may be poured in
accordance with this invention, namely, a round, a thick-
walled hollow round, a thin-walled hollow round, a bloom, a
slab, and a thin slab.
Modes for Carrylnq out the Invention
A preferred embodiment of an apparatus of the pres-
ent invention for casting rounds and an illustration of the
process of the present invention are shown in FIGS. 1 to 6.
Referring to FIG. 1, there is shown a permanent mold 20 com-
prising an inner tubular sleeve 21 and a concentric, spaced-
apart, outer tubular sleeve 22, both sleeves being circular
in cross-section, with sand 23 filling in the intermediate
space 24~ The inside wall 25 of the inner sleeve 21 defines
the sides of a casting cavity 26. A plunger 27 affixed to a
liftin~ screw 28 is lowered and elevated in the casting
cavity 26 by a screw jack 29 at the bottom of the apparatus.
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An air motor 31 drives the screw jack 29 and causes the lift-
ing screw 28 to lower and raise the plunger 27 at controlled
rates as required.
A pouring cup 33 is placed on top of the mold over
the inner sleeve 21 and a ladle 34 is provided above the cup
33 for releasing molten metal 35 into the pouring cup, as
shown in FIG. 4. At the beginning of a pour, the plunger 27
is in the top of the casting cavity 26, as shown in FIG. 1.
When the molten metal 35 is released into the pouring cup 33,
the plunger 27 is lowered at a controlled rate toward the
bottom of the mold so that at the end of its descent, as
shown in FIG. 5, the molten metal 35 fills the casting cavity
26. When the molten metal cools, there is formed a round or
other semi-finished product with a feed head 36 which is cut
off.
Referring now in more detail to the mold 20, the
outer sleeve 22 rests on a circular base plate 38 inside an
annular collar 39 to which the outer sleeve is welded. The
collar 39 in turn is secured by nuts 40 and tie-down studs 41
to the base plate 38, so that it can be disassembled if
desired. At the top of the mold is an annular top plate 42
to which the top of the outer sleeve 22 is welded. The top
plate 42 is provided with a center circular opening 43 with a
diameter slightly larger than the outer diameter of the inner
sleeve 21 and an upper circular countersunk groove or channel
44 into which fi~s an annular ring 45 (FIG. 2). ~he top
exterior of the inner sleeve 21 is welded to the inside of
the ring 45 so that the combination can be placed in the
opening 43 and suspended from the top plate 42 by engagement
of the ring 45 in the channel 44. The bottom of the inner
sleeve 21 is not restrained and can expand downwardly without
buckling or jamming as it absorbs heat from molten~metal.
Secured by bolts 47 to the bottom of the inner
sleeve 21 and inside the outer sleeve 22 is a round plate
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48. The round plate 48 has a layer of asbestos packing or
steel wool 49 between it and the sand 23 whi~h fills the
space 24 between the outside of the inner sleeve 21 and the
inside o~ the outer sleeve 22. There is clearance between
the outer circumference of the round plate 48 and the inside
surface of the outer sleeve 22. The asbestos packing 49 pre-
vents the sand 23 from running out and interfering with the
necessary downward expansion of the inner sleeve 21.
The surface of the inside wall 25 of the inner
sleeve 21 is preferably honed or otherwise made smooth and
regular. The inner sleeve 21 should be at least about 1-1/4
inches (3.2 cm) thick and is substantially thicker than the
outer sleeve 22 since it must maintain its strength and
integrity upon direct exposure to molten metal. At the same
time, the inner sleeve 21 shouId be as thin as possible to
avoid thermal gradient and hanger crack problems.
As noted, the space 24 between the inner sleeve 21
and outer sleev~ 22 is filled with sand 23, which is packed
into that space to support and strengthen the inner sleeve.
The space 24 may also be filled with other filler materials,
such as steel shot or grit, and the like. Preferably, the
filler is of varying size and is not a good conductor of heat.
The plunger 27 is shown in greater detail in FIGS. 2
and 3 and comprises a heavy steel swivel plate 50 which is
attached to the top of the lifting scr,ew 28 and is held in a
recess 51 in a heavy steel cylindrical block or piston 52 by
a ring 53 which is secured to the bottom of the piston by
bolts 54. Above the piston 52 is a circular retaining plate
56 which is bolted to the top of the piston with bolts 57. A
shim band 58 of steel about 0.015 inch (0.38 mm) thick such
as is used for shims extends circumferentially around and
axially above the top of the piston 52.
This shim band 58 is attached to the plunger piston
52 by means of nails 60 which extend through holes 61 in the
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retaining plate 56, through holes 62 drilled into the shim
band, and through holes 63 in the piston. The lower portion
58a of the shim band is provided with a multiplicity of slits
64 (FIG. 7) a~out 1 inch (2.5 cm) deep and about 1/2 inch
(1.3 cm) apart, and the lower portion is then annealed and
bent at a 90 angle to the other or upper portion 58b of
the shim band. The shim band 58 is disposed about the cir-
cumference of the retaining plate 56 and the plate is placed
on top of the piston 52 and bolted to the piston with bolts
57 which are tightened up at least finger-tight. This causes
the holes 61 in the plate 56 to line up with the holes 63 in
the piston 52. The nails 60 provide a positive means of
holding or retaining the shim band 58 on the piston 52 as the
piston descends.
The shim band 58 is positioned against the wall 25
of the inner sleeve 21 and smoothed out against it before the
holes 62 are drilled. The bolts 57 may be tightened up fur-
ther if~desired once the shim band 58 is so positioned.
The shim band 58 may be made of steel or other rela-
tively thin, flexible, resilient and strong metal which can
withstand the high temperatures involved in this process. A
suitable thickness for a steel shim band is about 0O015
inch. The thickness may range from as little as 0.005 inch
(0.13 mm) up to about 0.035 inch (0~89 mm).
Silica sand 65 mixed with a suitable core binder i5
then rammed into the space above the retaining plate 56 up to
within about l/8 inch (0.32 cm) of the top of the shim band
58 to form a refractory cap or cover 66 for the plunger 27.
The shape of the cover 66 is preferably concave as shown in
FIG. 2 so that~the sand is higher on the sides and lower in
the middle. A rammer having a diameter which is slightly
smaller than the diameter of the inner sleeve 21 and a curved
forward surface readily forms this shape. The top of the
shim band 58 should extend at least about l/8 inch (0.32 cm)
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above the top of the sand 65 so that the sand cannot rub off
against the inside wall 25 of the inner sleeve and cause dirt
and/or cracks in the casting. The sand 65 is then cured by a
carbon dioxide gas or "no bake~ system or otherwise to form a
hard refractory molded-in-place cap 66 on the piston plunger
27. After curing, any loose sand should be blown or brushed
off the cap 66 and the inside wall 25 of the inner sleeve.
The refractory core sand cap or cover 66 for the plunger 27
has to be made up in place as described for each cast. The
piston 52 and the retaining plate 56 can be used over again.
A new shim band 58 is preferably used for each cast.
There should be openings and clearances downwardly
from the refractory cover 66 so that any gases generated by
contact between the cover and the molten metal can escape
downwardly and are not forced upwardly through the molten
metal. The cover 65 is porous so that any gases blow down-
wardly through it, through nail holes 61 in plate 56, through
the clearance between plate 56 and piston 52, and through the
clearance between the inside wall 25 and piston 52 into the
inside of the mold.
The plunger 27 formed as described above makes a
sliding, molten-metalproof seal with the inside wall 25 of
the inner sleeve 21 and has the same cross-sectional shape as
the casting cavity 26 and product being cast. The term
"molten-metalproof seal" signifîes that molten metal does not
flow past the plunger or, if a small amount does flow past
the plunger, it is~ not enough to jam the plunger or in any
way damage the means for lowering and raising the plunger.
The lifting screw 28 and screw jack 29 are prefer-
ably a ball jack or screw jack such as shown in U. S. Patent
No. 3,323,777, and constitute the means for lowering and
raising the plunger 27. Preferably, there are ball bearings
in the worm gear in the housing 32 to provide what is called
a ball bearing screw jack. Also, there should be swivel
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means somewhere in the connection between the lifting screw
28 and the plunger 27 so that there is no tendency to rotate
the plunger when the screw jack is activated to lower or
raise the plunger. In the floor supporting the mold there
must be a bore hole 67 with a depth at least equal to the
travel of the plunger 27 in order to accommodate the lifting
screw 28 as it lowers the plunger downwardly into the mold.
The screw jack 29 is like either of the two screw jacks shown
in FIG. 15 and described hereinafter.
Mounted at the top of the mold 20 over the molding
cavity 26 is the pouring cup 33 (FIG. 1) which comprises a
cylindrical metal can 69 or section of steel pipe which is
filled with shaped, bonded refractory core sand 70. The sand
70 is rammed in place around a frusto-conical plug of suit-
able shape with the small end up and then cured. The sand 70
may have a silicate binder system which is cured with a car-
bon dioxide, a "no bake" system, or a system in which a
resinous binder is set by a catalyst and is cured with heat.
Sharp silica-~sand such as-used in foundries for cores may be
used for this purpose.
The pouring cup 33 directs molten metal into the
casting cavity 26 and forms reservoir or feed head 36 of
molten metal above the pIunger 27 as the plunger descends and
as the casting cools. In accordance with the known princi-
ples of the design of risers used in steel oastings, the
pouring cup 33 may be designed with the smallest cross sec-
tional area at the top and with the area increasing as the
cup extends downwardly, as shown. Pouring cups with the
greatest cross sectional area at the top may also be used.
The pouring cup 33 should be kept substantially full of
molten metal throughout the pour and should be substantially
full before the plunger 27 starts down. A probe or sensor 76
may be draped over the top of the pouring cup 33 so that when
molten metal reaches the tip of the sensor, it shorts out a
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circuit and causes the screw jack air motor 31 to start the
plunger 27 down.
At the beginning of a pour, the plunger 27 should be
as close to the top of the mold as possible and preferably
within less than 3 inches (7.6 cm) of the top of the mold 20
and as close to the bottom of the pouring cup 33 as is pos-
sible so as to minimize the distance through which the molten
metal falls.
The ladle 34 has a lining 78 of suitable refractory
material and is provided with a bottom opening 77 clo~ed by a
removable stopper 79. The ladle 34 can have a sllde gate in
place of the stopper 79 or the steel can be lip poured. When
the stopper 79 is lifted, the molten metal flows out through
a spout 80 beneath the bottom opening 77, as shown in FIG. 4.
The process of the present invention is illustrated
in FIGS. 1, 4, 5, and 6. In FIG~ l, the ladle 34 is above
the top of the mold with the stopper 79 closed to retain
molten metal in the ladle 34. The plunger 27 is at its
starting position at the top of the casting cavity 26~
-In FIG. 4, the~stopper 79 has been lifted and molten
metal 35, such as steel or stainless steel or nickel, is
being fed into the pouring cup 33 from the ladle 34 as the
plunger 27 descends. Molten metal 35 fills the casting
cavity 26 above the plunger 27 and substantially fills the
pouring cup 33. The ladle operator should try to pour molten
metal into the pouring,cup 33 at approximately the same rate
that it runs into the casting cavity 26 and maintain a good
supply of molten metal in the pouring cup.
The plunger 2~ is lowered at a rate of about 1/2 to
4 inches per second (1.3 cmjsec to 10.2 cm/sec) with a pre-
ferred rate for rounds of about l-l/2 to 2-1/2 inches per
second (3.8 to 6.35 cm/sec), depending upon the size of the
pouring cup 33 and the size~of the product and other factors
which will be~apparent to those skilled in the art. A
10-foot (3-meter) round can be cast in about 50 to 80 seconds.
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Long rounds, up to say 40 fee~ ~12 meters) long, may
be cast in accordance with this process, in which event it
may be desirable to vary the rata of ~escent o~ the plunger
in the course of the pouc.
In FIG. 5, the plunger 27 ha~ completed its descent,
forming a round casting 30. Anti-piping or insulating mater-
ial 83 is spread over the top of the metal 35 in the pouring
cup 33 to keep the metal in mol~en condition and to permit it
to feed downwardly into the casting under atmospheric pres-
sure as the casting cools. A suitable material is made by
Foseco, Inc., and is identified by the ~rademalk FERRUX,
which is a hot topping compound for iron and steel. If de-
sired or found necessary, an exothermic material may also be
used for this purpose.
In FIG. 6, the plunger has been raised to lift the
casting 30 and pouring cup 33 out of the mold 20 a short dis-
tance B which is at least about 3/4 inch (l.9 cm) and can be
up to 3 or 4 inches (7.6 to 10.2 cm). The plunger 27 is held
in this position as the casti~g cools and shrinks, and ma~ be
raised a second or third time to accommodate the shrinkage
and prevent the bottom of the pouring cup 33 f~om coming to
rest upon the top of the mold 20. It is important that a
lifting force be applied to the bottom of the casting as it
cools so as to maintain contact between the solidifying cast-
ing 30 and the inside wall 25 of the mold, break any areas of
adhesion between the mold wall and casting surface, and delay
the formation of an aic qap. The hydLostatic pressure forces
of the molten metal are thus taken up by the plunger and the
development of horizontal and vertical hanger cracks pre-
vented. The longer the period of time that the ~ides of the
solidifying casting can be held against the mold wall, the
cooler the casting will become, the finer its grain struc-
ture, and the better its surface.
The upwardly directed lifting force is accompli~hed
by reversing the plunger 27 for a short period until the
pouring cup 33 begins to lift off the top of the mold Z0.
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The plunger 27 is then stopped, the casting 30 is allowed to
shrink, and the pouring cup 33 may resettle onto the top of
the mold 20. The plunger 27 is again moved upwardly and the
upwardly directed force is reapplied until the pouring cup 33
again begins to lift from the top of the mold 20. This pro-
cedure may be repeated two or three or more times as needed
until the shrinkage of the casting 30 is completed. The
lifting or reversal step may be commenced immediately after
the plunger 27 reaches the bottom of the mold, and preferably
is begun within about a minute after the plunger reaches the
bottom of its cycle.
For the final step in the process, the riser or feed
head 36 formed in the pouring cup 33 is removed from the
round casting 30 by burning off or otherwise cropping at the
top of the casting, and the finished round is lifted from the
mold by appropriate lifting means such as tongs carried by a
crane and while simultaneously being pushed from the bottom
by the plunger 27. At this point, the cast product has sub-
stantially solidified and has cooled-and contracted away from
the inside wall 25 of the mold so that it can be stripped
from the mold.
In order to discourage or prevent welding of the
molten metai to the inner sleeve 21, a coating of zircon
oxide 55 or other suitable anti-weld agent may be applied to
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the top 37 of the inner sleeve 21 and to the inside wall 25
of the inner sleeve down to the plunger in its uppermost
position.
For steel molds, it is desirable to form and main-
tain an oxide coating on the inside wall 25 which acts as an
insulative layer between the molten metal 35 and the inner
sleeve 21. The oxide forms rapidly in the temperature range
of from about 1700 F to 2000 F (about 930 C to
1090 C) and for this reason, a sand with relatively good
insulative properties, such as silica sand 23, is used in the
space 24 between the inner sleeve 21 and outer sleeve 22 so
that the inner sleeve reaches the temperatures to form the
oxide. Within obvious design limits, the inner sleeve 21 is
also preferably made to be relatively thin from wall to wall
so as to reach the temperatures at which the insulative oxide
is formed quickly when exposed to the molten metal. An added
advantage of a thin inner sleeve is that a hotter sleeve ex-
pands more and thereby relieves pressures on the casting.
For an eight-inch (20.3 cm) round, the inner sleeve 21 should
be about l-l/2 inch (3.8 cm) thick.
In order to permit the inner sleeve 21 to reach the
temperatures at which the insulative oxide layer is formed on
its inside surface, the weight of the inner sleeve should
preferably be about l-l/4 to about l-l/2 times that of the
product being cast therein.
If desired, air can be blown through the silica sand
23 to cool it down should it reach temperatures above 2000 ?
F (1090C) and begin to lose its strength and structural
integrity. If it becomes desirable to increase the heat con- ;
ductivity of the material in the space 24 between the inner
and outer sleeves, steel grit or shot or similar material can
be mixed in with the sand.
The means for providing the controlled vertical
movement of the plunger 27 may be any suitable mechanical,
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pneumatic, or electrical means other than the screw jack
arrangement shown. ~ rod may be affixed to the plunger 27 at
the top and to a piston in a cylinder at the bottom and
powered pneumatically or by steam. A rack and pinion gear
arrangement may be used with pneumatic or electric motors.
Hydraulic systems are not favored because of fire hazards.
FIG. 8 illustrates an embodiment of this invention
for the manufacture of'hollow rounds. The permanent mold 20
is the same as that used in FIGS. 1-6. The plunger 100 is
similar to the plunger 27 of FIGS. 1-6 in that it has a
piston 101 and a shim band 102 which is filled with cured
core sand 103 to form a cover 104 for the plunger.
In order to make a hollow round, there is attached
to the plunger 100 a core 106 which is slightly greater in
length than the length of the round being cast plus the
height of a pouring cup 105. The core 106 is constrained and
guided above the pouring cup 105 by a jig 107. The core 106
comprises a hollow steel tube 108 filled with dry silica ~sand
109. The bottom of the core 106 is welded to a retaining
plate 110 of the plunger 100. The pIate 110 is in turn
bolted to the plunger piston 101 by means of four bolts 111
which are evenly distributed about the plate 110 in each
quadrant thereof. As will be apparent to those skilled in
the art, other means of attaching the core to the plunger may
be emp~oyed. .! :` , .
A ceramic sleeve 113 extends over the core 106 from
the jig 107 to protect the core from the impact of the molten
metal 35 and also to act as a guide for the core. Molten
metal 35 whi~ch is poured into a,refractory brick-lined pour-
ing'trough 114 runs into~and fills,the pouring cup 105. The
ceramic sleeve 113 is adjustable and of sufficient length to
protect the core 106 from the molten metal. The molten steel
35 may also,be,run,into the mold above the plunger 100 with a
side or bottom gate arrangement.
"` ~ 17~6~2
18
The means for positioning the jig 107 co~prises a
pair of lugs 117 and 11~ which are welded to the can 69 of
the pouring cup 105 and which support a vertical rod 119. A
horizontal member 120 is welded to the top of the rod 119 and
holds t~he jig 107 and ceramic sleeve 113 at one end over the
center of the casting cavity 26. A bolt 121 in the lug 118
holds the rod in an adjustable manner.
The plunger 100 is lowered at about the same rate as
that for rounds, or a little more rapidly because the metal
cools a little more rapidly. Depending upon sizes and con-
figurations, it may not be necessary to apply a reverse forg-
ing or liftiny force at the end of the descent of the plunger
100 in order to avoid hanger cracks and the like. The plun-
ger 100 may be used to strip the product from the mold after
the casting has substantially solidified and cooled enough to
shrink away from the inside wall 25 of the mold.
The core 106 should be considered to be expendable
and should not be reused. The core 106 can be stripped from
the casting after the casting has been stripped from the mold.
Other forms of cores may be used to cast hollow
rounds. A solid ceramic core, for example, may be used. A
rod-rein~orced and/or binder core may be used. The kind of
core will depend upon a number of practical factors which
will be apparent to those skilled in the art.
Using the same general arrangement, it is also con-
templated that a steel-reinforced copper round can be cast
which may then be roiled and possibly drawn into steel-
reinforced copper wire. A steel rod would be mounted on the
plunger in place of the core element 106 and copper poured
around it~ -As à further modification, a plurality of steel
rods could be mounted on the plunger, guided by a suitable
jig at the top, and a steel-reinforced copper round thereby
cast with a multiplicity of rein~orcements in it.
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19
In the same manner, other reinforced or combination
metal products may be cast of other high melting point met-
als. For example, the element 106 could be of larger diame-
ter and of steel and stainless steel poured around it to make
a clad round with stainless steel on the outside and a low
carbon steel core on the inside.
FIGS. 9-15 show another embodiment of the invention
for the production of slabs. Referring to FIG. 9, a mold 150
comprises two identical side blocks or side sections 151 and
152 which are supported in a parallel, vertical, upright
position on a stool or base plate 153 and positively main-
tained in that position by a multiplicity of hydraulic rams
154 which press against the outside surfaces of the side
blocks. The assembly is preferably placed in a concrete pit
155 and the hydraulic cylinder and piston mechanism or rams
154 are affixed to the sidewalls of that pit.
As shown in FIG. 10, the side blocks 151 and 152 are
separated and spaced apart by two pairs of identical vertical
end blocks 157, 158,`159, and 160. For one pour, the end
blocks 157 and 158 separate the side blocks 151 and 152 and,
together with a plunger 161, define one slab casting cavity
162. For the next pour,~the side block 151 is lifted over
the side block 152 and set down on the other side of it, as
shown by the side block 151' in broken lines in FIG. 10. In
that combination, the side blocks 152 and 151' are,separated
by the end blocks 159 and 160 and, together with a plunger
lS3, define a second slab casting cavity 164. A lifting
crane is attached to pad eyes 165 (FIG~ 12) on each side
block to lift and place it, as above described.
The purpose of~moving the side block 151 in this
manner is to alternately expose the faces of each block 151
and 152 to molten metal on sequential pours so that thermal
stresses are neutralized and are not built up from having
only one face of the side blocks exposed to the heat of the
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'. ~71~2
molten metal. The side blocks would warp and crack like
ingot molds if exposed to the extreme heat of the molten
metal on only one face.
The side blocks 151 and 152 are preferably made of
cast iron about 10 to 12 inches (25 to 30 cm) thick with
machined faces so as to be flat and smooth. Cast iron side
blocks are preferred for large slabs. For small slabs, bil-
lets, and blooms, slotted steell strongback reinforced side
blocks, such as shown in my U. S. Patent No. 3,948,311, may
be used.
Each of the end blocks 157-160 is identical and will
be described with reference to end block 157~ As best shown
in FIGS. 12 and 13, the end block 157 is made of a narrow
steel plate 168 about 4 inches (10 cm) thick with a plurality
of regularly spaced, horizontal slots 169 in the outer sur-
face thereof. An "I" beam strongback 170 is bolted onto the
outer or back surface of the plate 168 with a series of
Nelson studs 171 which are welded to the plate and extend
through holes 172 i~ the "I" beam. A plurality of cylindri-
cal rollers 173 are disposed horizontally in a U-shaped,
elongated channel member 174 above and below each stud 171 to
permit any necessary movement and adjustment when the molten
metal contacts the hot face of the plate 168 and causes it to
expand. The`slots 1'69 accommodate any`such expansion which
the ~I" beam strongback 170 resists. Each Nelson stud 171
has a nut 175 which'clamps t~e'channel member 174 against the
rollers 173. There'~is generous clearance in the holes 172 in
the "I" beam strongback through which the Nelson studs 171
extend in order to avoid any binding. Each end block is
assembled by horizontally placinq the plate 168 and the N I~
beam strongback 170, distributing the rollers 173, placing
the channel member 174 over the rollers, and bolting the unit
together by placing the nuts 175 on the ends of the studs
171. If desired, the rollers 173 can be held on axis pins or '
brackets in the channel member 174~
.
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1632
The end blocks 157-160 are attached to the edge of
the side block 152 which is not lifted, so as to be adjust-
able in and out and to provide slabs of varying widths.
Referring to FIG. 10, three brackets 177 are welded to each
end of the side block 152. The upper and lower brackets 177
are identical, and a horizontally extending plate 178 is
welded to each of these brackets. A housing 179 is mounted
on each end of the upper and lower brackets 177 adjacent to
one of the end blocks 157-160. Referring to FIG. 11, at
least two positioning screws 180 are attached to each end
block. Each positioning screw 180 passes through one of the
housings 179 in which there is a worm gear driven by a worm
gear drive shaft 181. One of the drive shafts 181 drives the
worm gears for both positioning screws 180 attached to each
end block. A handwheel 182 operates a second worm gear in
another housing 183 to rotat~: the worm gear drive shaft 181
and cause both positioning sc~ews 180 to move in and out the
end block to which they are affixed. There is thus a hand-
wheel 182 for each end block 157-160. The-handwheels 182
extend from housings 183 which are mounted in side-by-side
pairs on a plate 184 (FIG. 9), which is welded to the inter-
mediate bracket 177. Obv;iously, other means of positioning
and adjusting the end blocks may be employed.
Since the plungers 161 and 163 are identical, and
since only one plunger is used at a time, both plungers will
be described in detail with reference only to the plunger
161. With reference to FIG. 11, the plunger 161 for the
single slab mold comprises a block 187 affixed to and sup-
ported by two lifting screws 188 and 18g~ The block 187 cor-
responds to the piston 52 of the plunger 27 of FIG. 2. With
reference to FIGS. 12-14, a shim band 192 is L-shaped in
cross section and the lower leg is disposed in a peripherai,
horizontal slot 190 in the block 187. Holes 191 in the block
187 receive nails l94 which also go through holes 196 drilled
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1 ~71632
into the shim band 192 after the shim band has been suitably
positioned against the inside walls of the mold 150. Curable
core sand 193 is packed into the space above the block 150
within the shim band 192 and cured to form a flat, expendable
refractory cover 195 for the plunger 161.
The base plate 153 FIG. 11) is preferably provided
with holes 197 each large enough to accommodate one of the
lifting screws 188 or 189 but not the plunger 161, so that
the plunger always stays above the bottom edge of the side
blocks 157-160 and does not have to be realigned with them
for each pour.
In order to facilitate the manufacture of slabs of
different widths, the plunger block 187 is formed of a center
section 198 and two end sections 199, as shown in FIG. 11.
The si~e of the plunger 161 can be modified by removing one
or both of the end sections 199 from the center section 198.
As shown in FIG. 13, each of the end sections 199 is bolted
with a horizontal bolt 200 to the center section 198. Round
threaded-couplings 201 are bolted to the ends of the bottom
of the center section 198 and attached to the top of the
lifting screws 188 and 189 to affix the plunger 161 to the
lifting screws.
The arrangements to cover the top of the mold and
provide an integrated pouring cup are shown in FIGS. 11 14.
A pouring cup 203 comprises a can 204 inside of which is a
ceramic sleeve 208. The top of the casting cavity 162 is
covered with a layer 210 of core sand which is packed into a
thin metal trough 211 supported from below by the plunger 161
and is then cured. A ceramic sleeve 212 is placed on the
metal trough 211 prior to formation of the sand layer 210 and
is then surrounded with packed sand which is provided with a
binder as previously described.. A hole 213, of perhaps 1
inch (2.5 cm) in diameter, is made in the metal trough 211 so
that when molten metal is placed in the sleeve 212, it will
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23
quickly burn out the hole 213 and flow unrestrictedly into
the castir.g cavity 162 above the plunger 161. Obviously,
other arrangements to cover the top of the casting cavity and
provide a reservoir of molten metal over the cavity and
access to the cavity may be employed. For instance, metal
plates may be supported by the side blocks 151 and 152 and a
pouring cup placed between them.
Before a pour, the plunger 161 should be lowered
away from direct contact with the bottom of the metal trough
211 which supports the core sand layer 210 a distance of at
least 1/2 inch (1.3 cm). This provides space between the
refractory core-sand on the plunger 161 and the metal trough
211 through which moltPn metal can flow.
The plunger 161 is lowered and raised by a pair of
screw jacks 216 and 217 connected to the lifting screws 188
and 189, as shown in FIG. 11. An identical pair of screw
jacks 218 and 219 lower and raise the plunger 163 (FIG. 10).
There is thus one plunger and one pair of screw jacks for
each casting cavity sa that the same pair of screw jacks are
used for every other pour.
The controls for each of the screw jacks 216-219 are
identical and will be described with reference only to the
screw jacks 216 and 217. As shown in FIGo 15, an air motor
220 càuses a shaft 221 to rotate, which causes worms 222 and
223 mounted on opposite ends oP the shaft 221 to engage worm
gears 228 and 229 and elevate or lower the respective lifting
screws 183 and 189. The air motor 220 is reversible with a
variable speed. At one end of the shaft 221 is a top and
bottom limit switch 224 which is actuated by the shaft. The
limit switch 224 is electrically connected to a solenoid 225
which operates a ~our-way valve 226 and which is connected to
suitable electrical controls so that the valve 226 may be
operated to move the lifting screws 188 and 189 up and down.
A solenoid~operated brake 227 is mounted on the end of the
.
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24
quickly burn out the hole 213 and flow unrestrictedly into
the casting cavity 162 above the plunger 161. Obviously,
otber arrangements to cover the ~op of ~he casting cavity and
provide a reservoir of molten metal over the cavity and
access to the cavity may be employed. For instance, metal
plates may be supported by the side blocks 151 and 152 and a
pouring cup placed between them.
Before a pour, the plunger 161 should be lowered
away from direct contact with the bottom of the metal trough
211 which supports the core sand layer 210 a distance of at
least 1/2 inch (1.3 cm). This provides space between the
refractory corè-sand on the plunger 161 and the metal trough
211 through which molten metal can flow.
The plunger 161 is lowered and raised by a pair of
screw jacks 216 and 217 connected to the lifting screws 188
and 189, as shown in FIG. 11. An identical pair of screw
jacks 218 and 219 lower and raise the plunger 163 (FIG. 10).
There is thus one plunger and one pair of screw jacks for
each castin~ cavity so that the same pair of screw jacks are
used for every other pour.
The controls for each of the screw jacks 216-219 are
identical and will be described with reference only to the
screw jacks 216 and 217. As shown in FIG. 15, an air motor
220 causes a shaft 221 to rotate, which causes worms 222 and
223 mounted on opposite ends of the shaft 221 to engage worm
gears 228 and 229 and elevate or lower the respective lifting
screws 188 and 189~ The air motor 220 i5 reversible with a
variable speed. At one end of the shaft 221 is a top and
bottom limit switch 224 which is actuated by the shaft. The
limit switch 224 is electrically connected to a solenoid 225
which operates a four-way valve 226 and which is connected to
suitable electrical controls so that the valve 226 may be
operated to move the lifting screws 188 and 189 up and down.
A solenoid-operated brake 2~7 is mounted on the end of the
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t 171632
shaft 221 opposite the limit switch 224, and is electrically
connected to the limit switch and controlled thereby~ When
the limit switch 224 senses that the plunger 161 is at the
top or bottom limit of its travel, the switch automatically
operates the valve 226 and actuates the brake 227 to halt the
plunger.
One advantage of using an air motor as the source of
power for driving the screw jacks is ~hat when the plunger is
caused to lift at the end of its descent to apply a forging
force, the air motor will not stall and will provide substan-
tial lifting force at very slow or no revolutions of the worm
drive shaft 221.
A probe or sensor 230 (FIG. 9) is placed in the
pouring cup 203 and set so that when the pouring cup is sub-
stantially full of molten metal, it will start the plunger
downward.
The pit 155 in which the mold 150 is set is provided
with vertical plates 232 (FIG. 9) to which the rams 154 are
affixed; the plates extend above the ground level approxi-
mately one-third of the distance of the depth of the pit.
The above-ground portions of the plates 232 are buttressed by
vertical backing plates 233, which are set at right angles to
the pit plates 232 and mounted on horizontal mounting plates
234. The hydraulic fluid supply and controls for the rams
154 are placed out of and away rom the pit. The rams 154
press the assembly of side blocks 151 and 152 and end blocks
157-160 tightly together for each pour and are released when
the upwar~ forging force from the plunger 161 is discontinued.
As shown in FIG. 11, the screw jacks 216, 217, 218,
and 219 are mounted on a plate 236 in the bottom of the pit.
A pipelined bore hole 237 is provided in the ground immedi-
ately beneath the lifting screw of each screw jack to accom-
modate its respective lifting screw as the plungeF is lowered.
' 17163~
26
Slabs are cast in the apparatus of FIGS. 9-15 in ac-
cordance with the same process as that used for the rounds.
The plunger 161 is raised to the top of the casting cavity
162 and formed with the shim band 192 and the top cover 195,
as previously described, so as to have a sliding molten-
metalproof seal with the inside walls of the casting cavity
162. The pouring cup 203 or reservoir for the molten metal
is placed and/or ormed over the casting cavity 162. Molten
metal 35 is poured from the ladle 34 into the pouring cup
203, and when the pouring cup is substantially full, the
plunger 161 is caused to descend at a rate of about 1/2 to 4
inches per second (1.3 to 10 cm/sec) until it reaches the
bottom portion of the casting cavity, at which point it stops
descending and begins to push upward with at least a forging
force, and preferably a lifting force, on the solidifying
slab~ The slab is pushed upwardly, lifting the pouring cup
203 off the top of the mold 150. The upward movement of the
plunger 161 is then halted momentarily, and as the casting
shrinks the pouring cup 203 tends to settle back into place
on top of the mold 150. The upwardly directed lifting force
is then re-applied as before to keep the pouring cup 203 up
off the top of the mold 150 and to keep the cooling metal in
compression. Then, after another 10 to I5 minutes, the cast
slab cools and can be stripped or ejected from the mold by
releasing the pressure in the hydraulic rams 154 and raising
the plunger 161. The feed head formed in the pouring cup 203
may be burned off while the casting is in the mold, or the
casting may be lifted from the mold and cut off at a separate
location.
For the next pour, one side block (in the case of
the apparatus of FIGS. 9-15, the side block 151) is lifted
over the other side block ~the side block 152) and reassem-
bled to provide a second casting cavity I64 in which the hot
face exposed to the molten metal for ea~h side block 151 and
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27
152 is opposite from the one of the previous pour. The plun-
ger 163 is operated in the manner just described with respect
to plunger 161 in cavity 162.
FIG. 16 shows the various products and shapes which
may be manufactured in accordance with this invention. FIG.
16A shows a round 241 which may be made in the apparatus of
FIGS. 1-7v A round is cylindrical, 4 to 20 inches (10 to 50
cm) in diameter and 10 to 30 feet t3 to 9 meters) long. FIG.
16B shows a thick-walled hollow round 242 which may be made
in the apparatus of FIG. 8. FIG. 16C shows a thin-walled
hollow round 243 which may be made in the same apparatus.
FIG. 16D shows a billet or bloom which may be made in the
apparatus of FIGS. 9-15. A billet is usually square, in the
range of 2 by 2 inches (5 by 5 cm) up to 15 by 15 inches (38
by 3B cm), and at least 10 feet (3 meters) long. A bloom is
usually square, in the range of 6 by 6 inches (15 by 15 cm)
up to 12 by 12 inches (30 by 30 cm), and at least 10 feet (3
meters) long. Both billets and blooms can also be rectangu-
lar. FIG. 16E shows a slab 245 which may be made in the
apparatus of FIGS. 9-15. A slab is a relatively flat, oblong
rectangle with a width of from 24 to 80 inches (60 to 203 cm)
or more, a length of from 10 to 30 feet (3 to 9 meters), and
a thickness of from 2 to 10 inches (5 to 25 cm). A plate is
like a slab except that it is thinner~ FIG. 16F shows a
plate 246 which may be made in the apparatus of FIGS. 9-15.
FIG. 16G shows à headed round 239 whlch may be made in the
apparatus of FIGS. 1-7. The head 240 is provided for in the
pouring cup. In effect, a large pouring cup is provided with
a lower portion which is made to form the head 240 with the
remaining upper portion forming a feed head in the pouring
cup which is cut off. The present method of manufacturing
such products is ~o upset a round to form the head.
As will be apparent to those skilled in the art,
other semi-finished products may be made in accordance with
28
the process and appa~atus of the present invention. It is
believed that even irregula~ shapes such as "dogbones" can be
made in accordance with this invention.
A6 noted, the pou~ing cups, refractory covers fo~
the plunger, covering for the slab molds, and cores for the
hollow round are made from sand~binder mixtures such a~ are
used in foundries to make coLes. One such system is identi-
fied by the trademark CARSIL 700, which is a sodium silicate
binder/carbon dioxide gas system sold by the Foseco Found~y
Products Group in Cleveland, Ohio, U.S.A. Another system is
a "no bake" system in which a sodium silicate binder i8 set
up with a catalyst or chemical ha~den;ng agent, not carbon
dioxide gas, such as is sold by the Thiem Division of Koppecs
Company in Milwaukee, Wisconsin, U.S.A. under the name Thiem
Chem Bond 31. Other foundry core making systems may also be
used, preferably with inorganic binders such as fire clay,
Western bentonite, PoLtland cement, or iron oxide. Resinous
binders, such as phenolic resins, evolve a lot of ga~ and a~e
less desirable.
In systems which evolve water in the curing process,
it is advisable to "torch" the refractory cover and/or pour-
ing cup in order to drive off this water. This can be done
with a soldering or welding torch with care so as not to ha~m
the cured core sand.
It is contemplated that other forms of plungers and
which have a refractory cover and a shim band or the equiva-
lent and make a molten metal-proof sliding seal with the
sidewalls of the mold may be used in acco~dance with ~y
invention, as will be apparent to those skilled in the art.
Preformed ceramic di.scs or blocks may be substituted
for some of the sand, but should preferably be embedded in
sand 50 that there is a buffer layer of sand between the shim
band and the ceramic disc or block of at least about 1~2 inch
(1.27 cm). The reason for this is that most ce~amics have
high coe~ficients of expansion and may expand against the
shim band and bind or prevent the plunger from being lowered.
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~ 17163~
29
The forces acting on the shim band are substantial
and it must be well secured to the plunger. In place of the
FIG. 7 shim band, a suitable shim band may be made by welding
a row of Nelson studs to the band, which will serve to hold
it in place and avoid the necessity of slitting and bending
it. The studs are welded at right angles to one flat side of
the band in a row which extends ~he length of the band about
a one-third width distance in from one edge. In order to
assemble the shim band with the plunger piston or plunger
block, the shim band is disposed vertically, with the studs
extending horizontally from the lower portion of the shim
band and resting on the piston or block. A metal retaining
plate clamps and holds the studs onto the plunger piston or
block and in this way holds the shim band. The cured-in-
place refractory cover is over the retaining plate.
Bottom pouring ladles have been shown for filling
the molds with molten metal because they provide the minimum
exposure of the molten metal to the a~mosphere gases. In
some instances, lip pouring may prove to be preferable
because a greater volume of metal can be poured in a shorter
period of time.
~ s noted, a substantial lifting force should be
applied to the bottom of the casting very quickly after the
plunger has reached the limit of its descent or stroke so
that the tensile forces which build up in a casting as it
cools are greatly minimized or eliminated, and the casting
preferably is put in compression. When the casting is lifted
slightly out of the mold, it is clearly in compression under
its own weight pIus the weight of the pouring cup.
If the casting is not lifted out of the mold, the
lifting for~ce should be equivalent to at least half, and
preferably at least two-thirds, of the weight of the cast-
ing. Once th~ plunger stops its descent, the timlng for the
application of the upward lifting force may vary with the
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type of metal being cast, the type of product being cast, and
the tendency of the solidifying metal to adhere to the inside
walls of the mold. Likewise, the amounts of the lifting
force may vary with the same factors. For some products such
as hollow rounds or small slabs, the application of a lifting
force at the end of the pour may not be necessary. It is
believed, however, that the application of a lifting force at
the end of the pour universally improves the surface of the
casting and the grain structure of the casting.
The molds for making products in accordance with the
process o~ this invention are preferably made of steel or
cast iron. The molds may be made of other materials, how-
ever, such as copper or graphite. Copper molds must be
water-cooled and graphite is very expensive.
Even though steel and cast iron molds may be reused
many times, they are not indestructible. They are neverthe-
less characterized herein as "permanent molds" to distinguish
from molds which are destroyed with each pour or molds which
might last for a relatively limited number of pours~ such as
ingot molds.
The molds may be water-cooled, if desired, to speed
up the cycle. Even though it takes a little longer cycle,
however, air cooling is preferred because it does not involve
the mess and complications of water cooling. The molds of
FIGS. 1-8 can be air-cooled by blowing air through the sand.
For the round molds in particular, it is contemplat-
ed that the inside wall surface may be honed regularly in
order to keep it smooth and clean. The inside surfaces of
the slab molds may be cleaned by grinding or wire brushing
from time to time.
For the most part, it is contemplated that this
invention will be used for the manufacture of semi-finished
ferrous products, low carbon steels, and the various stain
less steels. It may be used in the manufacture of products
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of other high melting point metals such as nickel. More
generically, it is believed that ~his invention has applica-
tion ~n the casting of any product of uniform cross section
of any metal with a melting point of over 1000 C. This
would include, for example, copper products. It should be
understood, however, that a process which can cast ferrous
metal products can probably cast copper products because cop-
per is a lower melting, easier-to-handle metal. The reverse
rule does not apply, that is, a process which can cast copper
products probably cannot cast ferro~s metal products.
As is inherent in the nature of this process and
should be obvious from the foregoing description~ the prod-
ucts must have a constant cross-sectional shape or configura-
tion which corresponds to that of the mold and that of the
plunger. The length of the product may be varied at will by
the stroke of the plunger. If a short product is desired t
the descent of the plunger can be halted above the bottom of
the mold and the product length is thus determined by the
limit of the descent or stroke o~ the plunger. It is contem-
plated that relatively long rounds, blooms and billets may be
cast by my process, up to 40 feet (12 meters) or more in
length.
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