Note: Descriptions are shown in the official language in which they were submitted.
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DISK SCREEN FOR SEPARATING SOLID MATERIALS
DESCRIPTION
Field of application
The present invention regards a disk screen for separating solid materials,
according to the
preamble of the main independent claim.
The present disk screen is intended to be employed, in a per se conventional
manner, for
separating solid materials of various type, such as: solid urban waste, inert
fluvial material,
products of the organic fractions of the separate waste collection, compost
(for the refining
thereof), recycled wood, biomass, inert material, demolition material, land
drainage material
and dump material, glass, plastic, scrap metal and still other materials.
The disk screen according to the invention is therefore inserted in the
industrial field of
treating solid residues and is advantageously intended to be installed
downstream of plants for
crushing and grinding the same residues.
State of the art
Hereinbelow, the term "residues" refers - in an undifferentiated manner and
for the sake of
brevity - to any one solid material which requires being separated into its
components based
on size or mass.
Known on the market are numerous different apparatuses intended to be employed
for
separating solid residues in multiple fields of application, as well as
employing different
structural and functioning principles. Among such apparatuses, there are for
example the
following: mesh screens, screw screens, disk screens, ballistic separators,
drum screens, fluid
bed separators, electrostatic separators, magnetic separators and still other
apparatuses.
The present invention regards a screen of disk type, for example described in
the patent US
4972959.
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More in detail, the disk screens usually comprise a support structure, which
carries, rotatably
mounted thereon, numerous equidistant shafts in succession, parallel to each
other and rotating
in a same rotation direction. A group of disks is axially fixed on each shaft,
such disks
separated from each other by a distance less than the thickness of the single
disks, in order to
allow interposing the disks mounted on the contiguous shafts such that each
disk of any one
shaft is interposed between two disks of the adjacent front and rear shafts.
In the present field of the art, one thing that marks the characteristics of
the disk screen is the
screening surface. The latter is defined as the area of the openings delimited
between the disks
and the rotating shafts and is therefore indicative of the size of the
residues that are separated
1 0 by the screen, falling by gravity below the surface of the screening
surface.
A screen is known from the model DE 29711724 in which the disks mounted on the
rotating
shafts are maintained spaced from each other by spacer rollers directly fit on
the disks, so as to
rotate together therewith.
The disk screens of the above-described type have in practice proven that they
do not lack
1 5 drawbacks.
The main drawback lies in the fact that the presence of filiform elements
between the residues
to be screened, such as the presence of cables, strips, rags, plastic bags and
similar materials,
jeopardizes the correct operation of the screen. Such filiform elements in
fact tend to be
twisted around the disks and shafts of the screen and to obstruct the spaces
between the disks,
20 modifying the screen area and in the end compromising the screening
operations.
Consequently, repeated maintenance operations are frequently necessary for
these screens, for
cleaning operations, with consequent undesired stops of production.
In order to overcome such drawbacks, a disk screen is known from the patent EP
1106264 on
behalf of the same Applicant that is provided with idle sleeves interposed
between the disks,
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such sleeves having the function of preventing or at least limiting the
obstruction of the screen
area.
More in detail, each sleeve is axially mounted on the shaft between two disks
with clearance
adapted to allow it to freely idly rotate on the shaft or on a tubular body
provided externally
with respect to the shaft.
In operation, possible filiform elements that twist externally with respect to
the idle sleeves,
until they affect the disks mounted on the adjacent shafts, would not
compromise the
functioning of the screen nor would they cause stoppage since each sleeve,
being idle with
respect to the shaft on which it is mounted, would be driven in rotation
without constraining
1 0 the rotation of the shafts.
Also known, from the patent application WO -A- 2011045656 on behalf of the
same
Applicant, is a screen of the above-described type, in which a stabilizing
mass is arranged
within the idle sleeves in order to prevent or at least limit, during screen
operation, the sleeves
from being driven in rotation by the filiform elements, facilitating the
twisting of the latter.
The disk screens with idle sleeves of the above-described known type have in
practice the
drawback of allowing small-size material (such as sand, dust etc.) to be
inserted in the
clearance existing between the idle sleeves and the disks fit on the shafts,
so as to create a
mechanical connection between the rotating shafts and the sleeves themselves,
coming to
drive in rotation the sleeves to the detriment of their anti-twisting action.
Presentation of the invention
In this situation, the problem underlying the present invention is therefore
that of eliminating
the problems of the abovementioned prior art, by providing a disk screen for
separating solid
materials which is entirely reliable in operation over time.
Another object of the present invention is to provide a disk screen for
separating solid
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materials which prevents repeating maintenance operations due to the twisting
of filiform
elements.
Another object of the present invention is to provide a disk screen for
separating solid
materials which is capable of maintaining the idle rotation of provided
sleeves mounted on
rotating shafts.
Another object of the present invention is to provide a disk screen for
separating solid
materials which is simple and inexpensive to attain and entirely reliable in
operation.
Another object of the present invention is to provide a disk screen for
separating solid
materials which can be employed in a versatile manner in different application
areas.
Brief description of the drawings
The technical characteristics of the finding, according to the aforesaid
objects, can be clearly
seen in the contents of the below-reported claims and the advantages thereof
will be clearer in
the following detailed description, made with reference to the enclosed
drawings, which
represent a merely exemplifying and non-limiting embodiment of the invention,
in which:
- figure 1 shows a perspective image of the disk screen for separating solid
materials,
according to the present invention;
- figure 2 shows an enlarged detail of the screen of figure 1 in plan view,
relative to several
rotating shafts with a plurality of disks mounted thereon;
- figure 3 shows the detail of figure 2 in a side view;
- figure 4 shows a section view carried out along the lines IV - IV of figure
2;
- figure 5 shows an enlarged detail of the screen of figure 1 relative to a
disk with a sleeve
associated therewith, in perspective view;
- figure 6 shows an enlarged detail of the screen of figure 1 relative to a
disk with a spacer
associated therewith together with a rotating shaft portion, with the sleeve
of figure 5 depicted
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in exploded view.
Detailed description of a preferred embodiment
With reference to the enclosed drawings, reference number 1 indicates a disk
screen for
separating solid materials, subject of the present invention.
The screen 1 according to the invention is adapted to be employed for
separating solid
materials of various type, such as: solid urban waste, inert fluvial material,
products of the
organic fractions of the separate waste collection, compost (for the refining
thereof), recycled
wood, biomass, inert material, demolition material, land drainage material and
dump material,
glass, plastic, scrap metal and still other materials.
The disk screen 1 as schematically represented in the enclosed figures
comprises a support
structure 2, intended to abut against the ground, and on which a plurality of
rotating shafts 3 -
parallel to and spaced from each other - are rotatably mounted, as in
particular can be
appreciated in the image of figure 2 which represents a plan view of the
screen.
The rotating shafts 3 have longitudinal extension axes, indicated with Y,
which define a
preferably horizontal position, as illustrated in the drawings, but which can
also assume a tilt
without departing from the protective scope of the present patent.
Driving means 4 are provided that are adapted to carry the shafts 3 in
rotation, in the rotation
direction indicated by the arrow and marked with the reference R.
The shafts 3 all rotate in the same rotation direction R in order to move the
residues between
an inlet port and an outlet port in a per se entirely conventional manner, for
this reason not
described in more detail.
In accordance with a preferred embodiment of the invention illustrated in
figures 2 and 3, the
driving means 4 comprise an electric motor 4a and motion transmission means 5
mechanically
connected to the electric motor 4a. Such transmission means 5 in turn comprise
a chain 6
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wound as a closed loop and engaging with a pinion 7 fixed to the shaft of the
motor 4a and to
gear wheels 70 fit on each rotating shaft 2.
The screen 1 also comprises a plurality of disks 8, which are axially mounted
in succession
along the rotating shafts 3 in order to receive the rotation motion therefrom.
More in detail, on each rotating shaft 3, a group of disks 8 is mounted which,
for example, in
accordance with the enclosed figure 2, can be formed by nine and ten disks on
adjacent shafts
in succession.
The disks 8 of each group of disks are mounted spaced from each other along
the extension of
the longitudinal axis Y of the rotating shaft 3.
The screen 1 is also provided with a plurality of sleeves 10, each of which
comprising a
tubular body 11 mounted externally idle on a respective rotating shaft 3
between two disks 8
in succession.
The disks 8 are instead otherwise mechanically rotatably coupled to the
rotating shaft 3 in
order to receive the rotation motion thereof
For such purpose, the rotating shaft 3 for example has a male shaped profile
30, defined by the
form of its external surface and in particular by its cross section, and the
disk 8 has a female
shaped profile 80 joined to the aforesaid male shaped profile 30, and in
particular defined by a
through hole adapted to receive the aforesaid male shaped profile 30.
More in detail, the male shaped profile 30 has a polygonal (e.g. hexagonal)
cross section, and
the disks 8 have a female shaped profile 80 defined by a through hole 80 with
corresponding
polygonal shape traversed, to size, by the rotating shaft 3 which, due to the
aforesaid form
engagement, is thus susceptible to rotate the group of disks 8.
Preferably, each disk 8 has the shape of a hexagonal polygonal prism having
six flat faces 8C
that facilitate the advancement of the residues to be screened during the
rotation of the shafts
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2. In other embodiments of the present invention, the disks 8 can also have
external profiles of
different shape, advantageously adapted for facilitating the advancement of
the residues
between the inlet port and the outlet port.
Functionally, when the screen 1 is operating, the motor 4a - by means of the
chain 6 wound as
a ring on the pinion 7 of the motor shaft and on the gear wheels 70 of the
rotating shafts 3 -
rotates the rotating shafts 3 in the same direction, indicated with R, and the
hexagonal profile
with flat surface 8c of the disks 8 impacts with the residues, facilitating
the advancement
thereof via thrust along the screening plane in the advancement direction
indicated with A in
figure 1.
During such advancement of the residues, those with size smaller than the
openings defined
between the disks 8 and the sleeves 10 fall via gravity below the screening
plane, obtaining the
selection of the materials as a function of their size.
During screening, the presence of the sleeves 10 prevents, or at least limits,
the winding of
filiform residues around the rotating shafts 3. Indeed, the sleeves 10 do not
follow the rotating
shafts 3 during their rotation and are not integrally moved with the residues.
Each disk 8 is provided with two lateral faces 8A and 8B orthogonal to the
longitudinal axis Y
of the respective rotating shafts 3.
Such faces 8A and 8B are preferably substantially parallel and oriented in
opposite directions.
In accordance with the idea underlying the present invention, the lateral
faces 8A and 8B of
the disks 8 have a central depression 12 of circular form and each sleeve 10
in turn comprises
two annular shoulders 13 fixed to the ends of the tubular body 11, such
shoulders radially
extended with respect to the tubular body 11 itself, and inserted,
substantially to size, within
the central depressions 12 of the faces 8A and 8B of the disks 8.
Advantageously, the annular shoulders 13 of each sleeve 10 are fixed to the
ends of the tubular
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body 11 by means of fixing means, such as welding or screw means.
While the disks 8 rotate, moved by the rotating shaft 3, the sleeves 10 with
their annular
shoulders 13 remain mainly stopped, given that they are idly mounted on the
rotating shafts 3.
The provided object of the invention - to insert the annular shoulders 13
within the central
depressions 12 - allows obtaining the necessary clearance between the two
moving parts at a
position in which it is improbable that there will be an insertion of
undesired material that
would lead to connecting the sleeve 10 to the disk 8 and to the shaft 3, i.e.
bringing in rotation
also the sleeve 10, as if it were not idly mounted.
Otherwise, in the screens of the known type, the clearance between sleeve and
disks is
obtained on the tubular body, i.e. on the bottom of the space enclosed between
the disks, and
involves the undesired penetration of material with the consequent formation
of a mechanical
drive constraint between sleeves and disks that leads to the twisting of the
filiform material.
As can be observed in the enclosed figures 4, 5 and 6, the depressions 12 are
situated on a
lying plane that is more retreated and within the disk 8 than the plane
defined by the remaining
annular portions 9 of the lateral faces 8A, 8B, to which the depressions 12
are connected by
means of a sunken edge 120. Such edge 120 peripherally delimits the
depressions 12, is
therefore extended with an axial component within the thickness of the disk 8,
and faces, with
a minimum clearance, the circumferential profile 113 of the annular shoulders
13.
Consequently, the lateral areas of the annular shoulders 13, i.e. the most
external faces
directed towards the opposite shoulder 13 of the same sleeve 10, are embedded
within the
central depressions 12, i.e. they are slightly recessed in the disk 8 by a
thickness S illustrated
in figure 4.
In addition, advantageously, the annular shoulders 13 of each sleeve 10 are
radially extended
for a section 23 towards the longitudinal axis Y of the shaft 3 and are each
provided with a
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through hole 130 traversed by the same rotating shaft 3.
In accordance with a preferred embodiment of the present invention, the
annular shoulders 13
of each sleeve 10 are obtained with shaped metal plates, centrally provided
with the through
hole 130 for traversing the shaft 3.
The screen 1 also comprises preferably a plurality of spacer tubular bodies
14, each of which
is externally mounted on the rotating shaft 3 and is interposed and in
abutment between the
lateral faces 8A and 8B of two disks 8 in succession. Therefore, the disks 8
are inserted in
succession on the rotating shaft 8, alternating them with the spacer tubular
bodies 14 which,
being pressed between the contiguous disks, rotate together therewith.
In addition, externally with respect to each spacer tubular body 14, a
corresponding sleeve 10
is externally mounted with clearance.
Therefore, the longitudinal length D of each spacer tubular body 14 defines
the distance
between each pair of disks 8 and is slightly greater than the longitudinal
length d of each
sleeve 10, in order to ensure the axial clearance of such sleeve between the
pair of disks 8,
between which it is comprised.
In such a manner, each sleeve 10 can be rotatably moved in a free manner
around the
corresponding spacer tubular body 14 on which it is mounted.
In order to allow an entirely idle rotation of the sleeves 10 on the spacer
tubular bodies 14, a
radial clearance G is provided therebetween, illustrated as an example in
figure 4.
The finding thus conceived therefore attains the pre-established objects. Of
course, it can also
assume, in the practical attainment thereof, shapes and configurations that
are different from
that illustrated above, without departing from the present protective scope.
In addition, all details can be substituted with technically equivalent
elements, and the size,
shapes and materials used can be of any type in accordance with requirements.
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