U.S. patent number 3,712,593 [Application Number 05/127,210] was granted by the patent office on 1973-01-23 for method of and device for continuous preparation of granular material, such as foundry sand.
Invention is credited to Franz Szatmari.
United States Patent |
3,712,593 |
Szatmari |
January 23, 1973 |
METHOD OF AND DEVICE FOR CONTINUOUS PREPARATION OF GRANULAR
MATERIAL, SUCH AS FOUNDRY SAND
Abstract
A method and device for mixing, loosening, aerating and cooling
granular material is disclosed where the material to be treated is
introduced into two axially arranged cylindrical containers spaced
at a small distance one from another to provide a discharging gap
therebetween. At least one of the containers is rotated by a
driving motor so that the contacting grain layers in the gap will
rub together and subsequently are discharged by centrifugal forces
from the gap.
Inventors: |
Szatmari; Franz (Schaffhausen,
CH) |
Family
ID: |
4285124 |
Appl.
No.: |
05/127,210 |
Filed: |
March 23, 1971 |
Foreign Application Priority Data
Current U.S.
Class: |
366/7 |
Current CPC
Class: |
B01F
5/223 (20130101); B01F 13/00 (20130101); B22C
5/0404 (20130101); B22C 5/02 (20130101); B22C
5/0409 (20130101) |
Current International
Class: |
B01F
13/00 (20060101); B01F 5/00 (20060101); B01F
5/22 (20060101); B22C 5/04 (20060101); B22C
5/02 (20060101); B22C 5/00 (20060101); B01f
007/16 () |
Field of
Search: |
;259/2,5,8,151,147,148,153,12,14,19,1,146 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jenkins; Robert W.
Claims
What Is Claimed Is:
1. A method of the preparation of granular material, especially of
the mixing, separating and cooling of foundry sand, comprising the
steps of providing two quantities of said granular material,
feeding one quantity against the other quantity to an area of their
mutual contact, producing a rotary movement of one quantity
relative to the other quantity to cause a friction there between in
said contact area, and discharging centrifugally a layer of said
granular material from said contact area.
2. A method according to claim 1 further comprising a step of
producing a vibratory movement in at least one of said quantities
in addition to said rotary movement.
3. A device for the preparation of granular material, especially
for the mixing, separating and cooling of foundry sand, comprising
in combination, two container means axially arranged at a closely
spaced relation one to another to provide a discharging gap there
between, the facing ends of said container means being provided
with openings respectively, to allow the flow of said granular
material into said gap, and drive means coupled to at least one of
said container means to produce a rotary movement of one container
means relative to the other one.
4. A device according to claim 3 further comprising means for
vibrating at least one of said containers.
5. A device according to claim 3 wherein one of said container
means is in the form of a vertically arranged tube, the other
container is disposed beneath said tube and has a dish-shaped
configuration.
6. A device according to claim 5 wherein said tubular container has
a frustoconical configuration.
7. A device according to claim 5 further comprising agitating and
mixing members disposed within said tubular container means.
8. A device according to claim 3 wherein both container means have
tubular form.
9. A device according to claim 8 wherein said tubular container
means are arranged at an angle one to another.
10. A device according to claim 3 further comprising a discharge
chamber surrounding said gap and directing the prepared granular
material upon its discharge from said gap to a storage
container.
11. A device for the preparation of granular material, especially
for the mixing, separating and cooling of foundry sand,
comprising in combination
two container means axially arranged at a closely spaced relation
one to another to provide a discharging gap there between, the
facing ends of said container means being provided with openings
respectively, to allow the flow of said granular material into said
gap, and
drive means coupled to at least one of said container means to
produce a rotary movement of one container means relative to the
other one, said container means having tubular form, and
conveyor means disposed in each of said container means for
conveying said granular material from opposite directions to said
discharging gap.
12. A device for the preparation of granular material, especially
for the mixing, separating and cooling of foundry sand, comprising
in combination, two container means axially arranged at a closely
spaced relation one to another to provide a discharging gap there
between, the facing ends of said container means being provided
with openings respectively, to allow the flow of said granular
material into said gap, and drive means coupled to at least one of
said container means to produce a rotary movement of one container
means relative to the other one,
a discharge chamber surrounding said gap and directing the prepared
granular material upon its discharge from said gap to a storage
container, and
blower means, an annular passage disposed on top of said discharge
chamber, and conduit means for directing air from said blower means
through said annular passage to aerate the jetted layer of said
granular material.
Description
BACKGROUND OF THE INVENTION:
The present invention relates generally to the treatment of
granular materials. More particularly, this invention relates to a
method of an a device for the preparation, such as mixing,
loosening, dispersing and cooling of granular materials, especially
of foundry sands.
Methods and devices already known in which a combined assembly of
mixing, loosening, and cooling devices is employed. Conventional
mixing devices are provided with a container for receiving the
material to be mixed, and with rotatary mixing members or agitators
arranged in the container. The loosening devices or the so called
aerators are provided with a sand centrifuge for loosening and
cooling the granular material. In order to expedite the cooling
action of the granular material to be mixed, blowers for directing
an air stream into the mixed material are frequently employed. The
air stream from the blower produces an increased temperature
exchange with the relatively hot molding granular material
delivered from a foundry plant.
The disadvantage of such prior art combination of separate
processing devices for the preparation of foundry sands is in the
necessity to employ separate feeding devices for connecting
respective partial processing devices one to another. As a
consequence, relatively considerable construction costs result and,
in addition, the entire combined assembly requires considerable
floor space.
It is, therefore, an object of this invention to avoid the
aforementioned disadvantages of prior art methods and devices for
the treatment of granular materials.
More particularly, an object of this invention is to provide a
method and device which simplifies the preparation process for
granular materials.
Another object of this invention is to provide a single compact
device for performing all stages of the preparation process.
Still another object of this invention is to provide a method and
device which substantially reduce operative and construction
costs.
SUMMARY OF THE INVENTION
According to this invention, the above objects are attained by
providing a method where two quantities of the granular material to
be treated are brought into contact in a planar area, at least one
of the quantities is rotated and/or vibrated to produce mutual
friction at the area of contact and subsequently to discharge by
centifugal forces the abraded grains from the contact area.
The device for carrying out the above described method comprises
feeding means for continuously delivering granular material to be
processed, into a pair of containers. The two containers are
oxially arranged and spaced one from the other about an adjustable
distance to create a discharging gap there between. The facing ends
of both containers are provided with openings through which the fed
material enters the discharging gap. At least one of the containers
is coupled with a driving motor which can be provided with
additional means to impart to the container a rotary or a compound
rotary and vibratory movement; due to the rotation, the contacting
surfaces of respective quantities of granular material in both
containers start rubbing together and by centrifugal force the
processed material is discharged from the gap.
BRIEF DESCRIPTION OF THE DRAWING
For a better understanding of this invention, together with further
objects and advantages thereof, reference is made to the following
detailed description of the accompanying drawing wherein:
FIG. 1 is a sectional, elevation view of an embodiment of the
device for preparation of granular material according to this
invention;
FIG. 2 is a sectional elevation view of another embodiment of the
device according to this invention;
FIG. 3 is a sectional elevation view of still another embodiment of
the device according to this invention;
FIG. 4 is a cut-away elevation view, partly in section of agitating
and mixing means of the device of this invention; and
FIG. 5 is a cut-away elevation view, partly in section, of another
modification of agitating and mixing means of FIG. 4.
DETAILED DESCRIPTION
In the embodiment of the device for preparing granular materials,
as illustrated in FIG. 1, a vertical container is affixed to a
stationary supporting frame 2. Above a top opening 3 of the
container 1, there is disposed a conveyor 4 for feeding granular
material 5 to be prepared, such as foundry sand, for example, into
the container 1. It is advantageous to make the container of a
frustoconical configuration as to allow the granular material to
pass downwardly with minimum friction. This can be done preferably
by slightly inclining the inside wall 13 of the container 1 and by
increasing the diameter of bottom opening 8. Agitating and mixing
members 7 are fixedly mounted on a vertical shaft of a driving
device 6. The shaft projects coaxially into the container 1 and is
rotated by a driving device 6 which, as it will be explained later
with reference to FIGS. 4 and 5, can also bring the agitating and
mixing members 7 into horizontal or vertical vibrations. The shape
arrangement of the agitating and mixing members 7 can be variously
modified according to required operative conditions. For example,
it is possible to make those members 7 in the form of horizontally
projecting rods, or rake-shaped projections or in the form of a
spiral conveyor. Opposite to the bottom opening 8 of the container
1 there is located at a certain small distance from the bottom rim
of the wall 13 a dish-shaped second container 10. The second
container 10 is firmly connected to a driving shaft 15 of a motor
14. The motor 14 is provided with laterally projecting swivel rods
which are movably supported for tilting the motor 14 about a
horizontal axis. In addition to a rotary movement, the driving
shaft 15 is thus adapted for importing a vibratory movements in
horizontal and vertical planes to the second container 10 as it is
indicated by dashed lines in FIG. 1. The top opening 9 of the
second container 10 faces the bottom opening 12 of the first
container 1, and respective side walls 11 and 13 are spaced one
from the other to form a circular discharging gap 12 between the
container 1 and the container 10. The clearance of the gap 12 is
adjustable by means of oblong vertical holes 34 in the wall of
discharging chamber 17 in which the bearings for the swivel rods of
motor 14 are fastened by bolts and nuts 16. The top of the
cylindrical discharging chamber 17 is provided with cover 19 having
an annular passage 21 adjacent to the periphery of the wall 13 of
the container 1. The annular passage 21 communicates through a
ring-shaped conduit 22 with an air blower 23. The discharging
chamber 17, conduit 22 and air-blower 23 are suspended on the
supporting frame 2. The bottom of the discharging chamber 17 open
into a storage bin (not shown).
In accordance with the method of this invention, the operation of
the device for the preparation of granular material is as
follows:
The material to be treated, for example foundry sand 5, is first
fed by conveyor 4 through the inlet top opening 3 of the first
container 1 and falls there through to the bottom of the second
container 10 where it piles up as high as to reach the interior of
the first container 1. As soon as the sand in container 1 reaches a
predetermined level, the mixing action is started by the actuation
of agitating and mixing members 7. Subsequently, the motor 14 is
switched on and the shaft 15 thereof which is connected a little
excentrically to the bottom of the second container 10 starts
rotating and the second container 10 is driven at a relatively high
speed.
Simultaneously, due to the excentricity of the mounting of the
shaft 15, the second container 10 vibrates in a horizontal plane.
Due to this compound motion, the granular mixture 5 is
centrifugally jetted out against the inside wall of the discharging
chamber 17. Simultaneously, the air blown through the annular
passage 21 in the direction of arrow 24 cools the jetted layer 33
of the sand mixture and disperses respective particles. The inside
wall of the discharging chamber 17 can be with advantage provided
with an elastic coating, such as of a plastic material.
Due to the dish-shaped configuration of the second container 10,
the accumulated granular material during the rotation of the
container 10 causes rubbing or friction in the area of the
discharging gap 12 between the bottom layer of the granular
material in the stationary first container 1 against the rotating
and top layer in the second container 10. In this frictional area
of the gap 12, the mixing action is most effective since due to the
direct friction of one granular layer against a plurality of grains
in the adjacent layer, the activating motion is attained in
addition to and irrespective of the motion of the agitating and
mixing members 7. As a result, the initially added binding material
and other additives are disintegrated and uniformly coat surfaces
of individual grains. In the course of the centrifugal discharge of
the relatively highly tempered granular mixture coming from the
foundry plant, there occurs a temperature exchange with the cool
air in the discharge chamber 17. To increase the cooling effect,
the blower 23 can be set into operation for blowing cool air
through the sand veil 33 jetted-out from the circular discharge gap
12, as shown by arrow 24.
In the preparation of granular substances such as, for instance,
molding and grain sands, ceramic masses and similar materials, the
homogenizing stage of the preparation process is of decisive
importance. In this stage the treated mixture which consist of
grains of different sizes, is not only homogenized but also very
frequently mixed with powdery, liquid or pesty binders and
additives whereby as it is required in molding sands, there must be
also provided in as short time as possible a uniform envelop of the
added binder around the grains. The binder is added very frequently
in minute quantities only. For this reason, the kneading and
frictional processes within the granular mixture itself are
essential since the energy introduced into the mixture is thereby
most effectively distributed and the resulting motion provides the
optimum homogenization of grains and coating of their surfaces.
If there are employed additives and binders which produce, due to
mere upper surface tension only or due to inherent adhesive forces,
a more or less strong cohesion in the prepared material so the
latter material may not be processed in a clotty condition but it
must be prepared for a further processing in as loose condition as
possible, i.e. uniformly separated into individual grains. These
requirements are fully met by the above described method of and
device for the preparation of granular mixtures of this
invention.
Further modifications of the invention are illustrated in FIGS. 2
and 3. With reference to FIG. 2, there is schematically shown an
embodiment in which two devices of FIG. 1 are operatively coupled
in a vertical arrangement so that the outlet of the upper device
communicates with the inlet of the lower device. In this manner,
the mixing, homogenizing and dispersing actions are repeated and
thus optimized.
In the device as illustrated in FIG. 3, the granular material 5 to
be processed is fed to the discharging gap 12 from two opposite
directions. One stream of the material to be processed is fed by
means of a conveyor, preferably a screw conveyor 26, into a first
cylindrical or tube-shaped container 24. Another stream of material
5 is fed from the opposite direction by means of a second screw
conveyor 27 into a second cylindrical or the tube shaped container
25. The two containers as well as the coaxially disposed screw
conveyors 26 and 27 may be arranged horizontally, spaced by a
small, adjustable distance one from the other, so that a vertical
discharging gap 12 will result. Instead of screw conveyors, it is
possible, of course, to apply other conveying means such as
plungers, membranes, pressure air and the like. By contrast to the
embodiment of FIG. 1, both cylindrical containers 24 and 25 are
supported for rotary and/or excentrically vibrating movements from
opposite directions, as indicated by arrows 28 and 29. The
amplitude of the range of vibrations of containers 24 and 25 is
indicated by dashed lines 30. By means of the resulting
counter-directed movements of the granular mixture in containers 24
and 25, the contacting grains in the gap 12 are subject to
centrifugal and frictional forces similarly as in the previous
embodiments.
The processed grains rub together and, at the same time are jetted
outwardly by centrifugal forces against the wall of discharging
chamber 17, where the discharged sand layer 33 is dispersed and
aerated in an analogous manner as it has been explained with
reference to FIG. 1. Cooling air delivered from a blower 23, is
conducted through vertical ring-shaped conduit 31 and passes
through an annular passage 21 into the interior of the discharging
chamber 17, as indicated by arrows 32. From the discharging chamber
17, the processed granular material falls into a storage bin (not
illustrated).
In a modification of the embodiment according to FIG. 3, the two
facing containers 24 and 25 can be arranged at a certain angle one
to another, instead axially, in this case, the intermediate
discharging gap 12 will have unequal clearance around its
periphery. The inclined position of the containers 24 and 25
enables that the two opposite streams of granular material 5 may be
conveyed to the area of the discharging gap by force of gravity
only which can also be applied for the creation of the frictional
or rubbing pressure. As it has been already mentioned, the
clearance of the gap 12 can be adjusted by axial displacement of
the containers 24 and 25.
FIG. 4 illustrates a modification of drive means 6 for rake-shaped
agitating and mixing members 7. The drive means 6 rotates the shaft
of members 7 over an excentricnot illustrated of any suitable
design so that those members 7 exercise in addition to their rotary
movement vibrations in horizontal plane, as indicated by dashed
lines.
FIG. 5 shows another variation of the drive means 6 for rod-shaped
agitating and mixing means 7, where the supporting shaft of members
7 performs, in addition to its rotary movement, vibrations in a
vertical plane, as indicated by dashed lines. The vertical
vibrations can be produced by a can shaft driven by drive means
6.
It is possible, of course, to design drive means in such a manner
as to perform, in addition to a rotary movement, vibrations both in
horizontal and in vertical planes. Further modification may also be
made in the spirit of the invention. It is possible, for example,
to avoid the application of auxilliary parts of the device such as
of the blower 23 for cooling the discharged material, or of the
agitating and mixing members 7 which, even if useful for cooling or
mixing process, may under certain operational circumstances occur
as unnecessary.
The device according to this invention is suitable for the
preparation of sands of heterogenous composition such as of the so
called "Cold Box" or "Hot Box" Sands as well as sands which contain
chemically hardening binders, especially synthetic resins, water
glas, cement and similar binders.
The invention may be embodied in various other constructions and
various changes may be made as come within the scope of the
accompanying claims.
* * * * *