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Патент USA US2122825

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Patented July 5, 1938
ear: sari orrica ..
" rmxnieinr'rnr FOUNDRY SAND MoLns
Victor Stobie, Harrogate, England
Application January. 18, 1937, Serial No. 121,208
In Great Britain November 21,, 1935.
2 Glaims. (Cl. 22——193)
This invention relates to the making of sand
shapes in molding'boxes, for use in metal foun
dries. More particularly, the invention relates
to the projection of sand bonded with oil or
other usual adhesive, by pneumaticenergy into
the molding boxes, the sand being liberated at
of air are: the cost of. theextra compressedair;
and the blowing. away of sand from thelmold"
by the high. volume of air which accompanies
the sand on its exit fromthe pipe into the. mold;
ing box.
the sand exit of the sand conveying conduit into
free atmosphere before it enters the molding box.
It has. been proposed to project sand into
lol‘mo'lding'boxes by two principal means. One has
been to supply compressed. air to the surface of
supplied into a closed sand container containing,
molding‘ sand, and the sand is liberated through
an aperture into free atmosphere. The steep
sand in a closed sand container, and to clamp
or fasten the molding box to the bottom of the
sand container, which latter is provided with an
15 exit through which the sand travels immediately
higher velocity than by the described previous
from the sand container into' the molding box.
By that method, the molding box forms a closed,
or almost closed, receptacle continuous with the
machine, and when the sand and its contained
20 compressed air enter the molding box, the air
pressure in the molding box rises and becomes a
back-pressure acting against the entering sand.
Small openings are sometimes provided in the
molding box, but they are quickly sealed by the
25 incoming sand and, in any case, the very rapid
flow of sand and its contained air into the mold
ing box causes atonce a strong back-pressure
of air. This back-pressure becomes greatest in
deep recesses inside the molding box, and pre—
30 vents the sand being well compacted in those
parts of the mold. The sand velocity reduces
progressively with the ?lling of the molding box
because the back-pressure increases, so there is
absence of uniformity. A further disadvantage
35 of that system is that, as the point of exit of
the sand from the sand container is ?xed in
position relative to the inlet of the molding box
clamped to it, most of the sand has to change
its direction of travel within the molding box
40 several times before it can ?ll it.
This also acts
against the compactness of the sand shape, and
the sand may not ?ll the molding box.
The other principal previous pneumatic sys—.
tem of ?lling molding boxes with bonded sand
consists in blowing air from a jet at the end
of a pipe into a larger pipe whose opening at
one end is axially concentric with the jet, and
supplying sand between the jet and the larger
pipe so that air from the jet will carry the sand
50 forward into the larger pipe, from the other end
of which it ?ows into the molding box.
disadvantage of this system is that a much
larger volume of air is required vfor a given
amount of sand than by the other previous sys
55 tem. The inconveniences of this greater amount
By the present invention compressedpair is
pressure gradient thus ruling causes the sand in“
to travel to and through the exit at a much
system which utilizes a closed sand container.
The high momentum gained by the sand at the
exit is then utilized to project thesand ?rst
across open atmosphere, to liberate the air con
tained between the grains of the sand, ‘and then
into the molding box, where the balance of ki
netic energy in the sand expends itself on com
pacting the sand therein.
In order that the sand may be directly pro
jected into all parts of the molding box, the lat
ter may be moved into di?erent positions under
the out?owing column of sand. Alternatively,
a ?xed or ?exible pipe may be attached to the 25
sand exit of the sand container, and the sand
projected from the other end of that pipe
through free atmosphere into the molding box.
In the accompanying drawing, the ?gure illus
trates diagrammatically in elevation, partly sec 30
tional, a pneumatically energized sand shape
making machine which conforms to one embodi
ment of the present invention.
Referring to the drawing, there is provided a
container l for the sand 2. Overlying the sand 35
is the plunger 3 provided with holes 4, the
plunger being free to reciprocate and follow
along after the sand as the level of the sand
drops with use. The container l is provided
with an inlet 5 for compressed air from any ' 40
suitable source and an outlet 6 for the sand. At\
the bottom of the container l is a ?xed exten
sion 1 which is provided with. a conduit 8 con
nected with the sand outlet 6. In the modi?
cation disclosed. a ?exible hose or extension 9 45
is connected to the conduit 8 by a suitable cou
pling l0. Adjacent the ultimate sand outlet is
themolding box ll into which the sand is to
be projected consecutively at di?'erent places
or angles, 12 representing the spray of sand pro- "
jected through free atmosphere into the mold
ing box.v
My method of projecting sand through free
atmosphere into the molding box is not to be com
pared with sand blasting systems, nor the air 5s
jet method previously proposed for ?lling mold
ing boxes. The forward movement of the sand
by my method is due to the progressive expan
sion of the compressed air residing between the
grains of the sand, whereas all injector or
ejector systems operate by the sand being car
ried, as a passenger, on a moving stream of air
from a jet. The sand and the compressed air
between its grains do not occupy within the
10 present apparatus a greater volume than does
sand alone in open atmosphere. In ejector or
injector systems, the injected air is added to
the volume of the sand and its already contained
jector or ejector entails very much of the en
ergy in the compressed air being delivered to‘
the jet being lost and, therefore, large excess
of compressed air must be delivered to move the
sand forward.
I claim:
1. The method of projecting bonded sand into
a molding box consisting in subjecting sand in
a closed sand container toI air pressure so as
to ?ll the normal spaces between the sand grains
with compressed air, letting the sand travel on
a steep pressure gradient through an exit from
the sand container, through which exit the sand
is forced forward by the progressive expansion
of the compressed air contained between the 15
ratio of air to sand. Another reason is that sand grains, and passing the sand stream from
sand de?ects much of the air stream from the the end of the exit through open atmosphere
jet into directions not useful for the forward. into the molding box.
2. The method of making sand shapes in
movement of the sand, and therefore more air
molding boxes comprising subjecting bonded 20
20 is necessary to move the sand forward, and much
air; which is one reason why injector or ejector
methods applied to sand molding produce a high
of the wasted air is also carried forward by the
stream. Additionally, injectors and ejectors, other
than those used with steam condensation for ?ll
ing boilers with water, are known to be ine?i
25 cient unless the aspiration of the material to
be moved is effected in a cascaded succession of
jets, on the principle of such well known injec
tors as the Kortin-g and the Eynon-Evans. Such
said to air pressure so as to ?ll the normal
spaces between the sand grains with compressed
air, forcing the sand forward on a steep pres
sure gradient by the progressive expansion of
the compressed air contained between the sand 25
grains through an exit and passing the sand
stream from the end of the exit through open
atmosphere into the molding box.
a principle is, however‘, inoperable with sand,
30 and‘ the ine?iciency of the ordinary type of in
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