Note: Descriptions are shown in the official language in which they were submitted.
20381~3
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Title
DISCHARGE APPARATUS FOR BINS
Background of the Invention
i. Technical Field
This invention relates to an apparatus for discharging
material cont~;neA in bins, and is particularly suitable for
metered discharge of the material. More specifically, the
invention is advantageously employed for handling
nonfree-flowing materials such as wood chips.
ii. Prior Art
Many processes and operations require the storage of
materials in bins or hoppers. If the material is
nonfree-flowing, apparatus must be provided to extract the
material from the bin or hopper. In the past, a number of
discharging devices have been used, including screw feeders,
chain conveyors, stokers, slat conveyors, and the like.
Integrating heretofore known discharge devices with a hopper
or bin complicates the overall construction and increases the
capital expense for installing storage facilities.
Most previously known discharge apparatus operate
substantially horizontally inside the bin or hopper, near the
bottom thereof. After the material is carried outside of the
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bin, it is deposited in a vertical outfeed chute. Often, the
floor or base of the bin or hopper is inclined opposite the
direction of material flow. When the process requires that
the flow or discharge of the material be controlled or
metered, a limited opening is often provided through which the
material is extruded. The material flow rate is controlled by
controlling the size of the opening through which the material
is extruded. The horizontal movement of the material, removal
along inclines from the bin, and extraction through metering
gates requires the expenditure of significant amounts of
energy. Energy requirements are even further increased if the
material being stored and extracted does not shear easily.
High shear forces frequently cause compaction of the material
near the metering points, which creates bridging across the
bin and results in efficient or nonoperation of the
discharging device. If the process in which it is used
requires continuous flow from the discharge device, valuable
production time is lost while any plugging or bridging is
cleared.
Summary of the Invention
It is, therefore, one of the principle objects of the
present invention to provide a discharge apparatus for bins
and hoppers which is uncomplicated in construction and
operation, thereby facilitating integration of the discharge
apparatus with a bin or hopper at mi n i m~ l expense.
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Another object of the present invention is to provide a
discharge apparatus for bins or hoppers which induces and
controls vertical, gravity enhanced flow of material from the
bin, thereby reducing the energy required for extracting the
material from the bin.
A further object of the present invention is to provide a
discharge apparatus for bins or hoppers which modulates the
flow of material from the bin, and which m;nim;zeS or prevents
compaction and bridging of the material above the discharger.
A still further object of the present invention is to
provide an apparatus for discharging nonfree-flowing material
from a bin or hopper which is particularly suitable for
discharging wood chip wafers, and which can be optimized in
structure for the material which will be discharged.
A still further object of the present invention is to
provide a discharge apparatus for bins or hoppers which
extends across the full width or length of the bin or hopper,
and which provides a metered flow of material from the bin or
hopper without the use of metering gates, or other restrictive
openings.
These and other objects are achieved in the present
invention by providing a bin or hopper having a bottom
discharge opening across its full length. A plurality of
rolls are provided near the bottom of the hopper, and are
arranged and configured with respect to the type of material
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being discharged such that, during rotation, the rolls sift
and dislodge material from the bin, allowing the material to
fall between and among the rolls and out of the bin or hopper.
When the rolls are not being rotated, the opening from the bin
is effectively closed by the rolls, thereby preventing
additional material from falling out of the bin.
The structure of the rolls, the arrangement of rolls, and
the number of rolls used may vary depending upon the material
to be stored in and discharged from the bin. For example,
smooth or ribbed rolls may be arranged in the discharge area
of the hopper, in two or more rows. Normally, lower rolls are
positioned in the open area defined by rolls in upper rows.
The rolls may have radially extending fins or plates which
intermesh with the fins or plates radially extending from
adjacent rolls. The rolls may be parallel to or perpendicular
to a longittl~; nA 1 extent of the bin opening. In some
applications, it may be particularly advantageous to dispose
the rolls angularly in the horizontal, or vertical planes with
respect to the discharge opening. In other variations, the
rolls are not cylindrical in shape, but may be conical.
Still, other variations include rolls formed from staggered
cylinders alternately arranged with staggered cylinders from
adjacent rolls, or other shapes in which adjacent rolls
compliment each other. For example, one roll may be
essentially concave in shape, with the adjacent roll being
convex.
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Additional objects and advantages of the present
invention will become apparent from the following detailed
description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional view of the discharge area
of a hopper employing a discharge apparatus embodying the
present invention.
Figure 2 is a cross-sectional view of the bin or hopper
shown in Figure 1 taken along line II - II of Figure 1.
Figure 3 is a view of 2 adjacent rolls of the discharge
apparatus shown in Figures 1 and 2.
Figure 4 is a view of a modified embodiment of a roll
pair for the discharge apparatus of the present invention.
Figure 5 is a view of another modified embodiment of a
roll pair for the present invention.
Figure 6 is a view of yet another modified embodiment of
a roll pair for the present invention.
Figure 7 is a cross-sectional view of a bin having a
discharge apparatus of the present invention utilizing a
single row of intermeshing rolls.
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Figure 8 is a cross-sectional view of the bin and
discharge apparatus shown in Figure 7, taken along line VIII -
VIII of Figure 7.
Figure 9 is a cross-sectional view of a smaller bin
utilizing an alternate arrangement of a single row of rolls
for the discharge apparatus.
Figure 10 is a cross-sectional view of yet another
embodiment of the discharge apparatus of the present invention
in a bin or hopper.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now more specifically to the drawings, and to
Figure 1 in particular, numeral 10 designates a bin or hopper
having disposed therein a discharge apparatus 12 embodying the
present invention. Apparatus 12 is provided for effecting a
continuous met~red discharge of a material 14 to a conveyor
16.
Bin 10 includes parallel vertical walls 18 and 20
defining 2 sides of the bin, and angularly converging walls 22
and 24 disposed between the vertical perpendicular walls.
Discharge apparatus 12 is disposed in the lower portion of the
bin or hopper 10, and separates the bin into a retention area
thereabove, generally indicated by numeral 26, and a discharge
area 28 therebelow. It will be understood by those familiar
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with the art that the size and shape of the bin or hopper 10
may vary. Above the angular walls 22 and 24, bin walls may
extend substantially vertically. The bin or hopper may
include angular portions on all walls, may include only
vertically oriented walls with no angular walls, the walls
defining right angles in the corners, may be round or oblong
in cross-section thereby defining no corners, or the like.
The present discharge apparatus can be adopted for use in any
shape bin or hopper, with similarly advantageous results.
Material sifted from the retention area 26 by discharge
apparatus 12 falls through discharge area 28 onto conveyor 16.
The conveyor shown in Figures 1 and 2 is a belt conveyor
having an endless, revolving receiving belt 30 guided by
turning rolls at either end, one of which is shown in Figure 2
and designated with numeral 32. Additionally, idler guide
rolls 34 are disposed within the loop defined by the belt 30.
It will be understood by those knowledgeable in the art that
other types of conveyors such as slat conveyors, augers, or
the like may be used berea.th the bin 10 for receiving and
transporting material therefrom. In some processes, it may ~e
advantageous to provide a loading chute beneath the bin, for
transferring material from the bin to trucks, railroad cars,
or the like, or, in other operations, it may be advantageous
to dispose sizing screens or other process apparatus beneath
the bin 10.
As shown in Figures 1 and 2, discharge apparatus 12
includes an upper row of rolls 40, 42, 44, and 46; and a.lower
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row of rolls including large outer rolls 48 and 50; and a pair
of smaller inner rolls 52 and 54. The lower rolls are
positioned to obstruct the flow of material along the paths
defined by the upper rolls. Thus, lower roll 48 is positioned
in the vertical material flow path generally indicated by
arrow 55 and defined by upper rolls 40 and 42, and lower roll
50 is positioned in the vertical material flow path generally
indicated by arrow 56 and defined by upper rolls 44 and 46.
The pair of small lower rolls 52 and 54 are cooperatively
disposed in the vertical material flow path generally
indicated by arrow 57 and defined by upper rolls 42 and 44. A
single, larger lower roll can be used in place of the pair of
smaller lower rolls 52 and 54. For some materials, it may be
advantageous to use a num~ber of different size rolls within
each row, either upper or lower. Hence, it is not essential,
and in some applications perhaps even undesirable for all of
the upper rolls to be equal in size. In some situations, it
may be advantageous to use more than two rows of rolls, and
additional rows can be provided beneath the lower row or above
the upper row shown in Figure 1.
Each of the rolls extend from one side wall of the bin to
the opposite side wall, and each is journalled in bearings 58
at either end. Floating bearings can be used advantageously
to support the rolls and prevent damage from passage of
oversize or hard material through the discharger.
In the embo~;ment shown in Figures 1 and 2, each of the
rolls is essentially smooth and cylindrical, and has dis~osed
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on the surface thereof a plurality of outwardly extending
knobs or cleats 60. The knobs or cleats 60 perform a raking
or sifting operation on the material, moving it from the
retained area and positioning it for passage through the space
between adjacent rolls.
The rolls can be disposed horizontally, or, as shown by
the phantom line 62 in Figure 2, the rolls may be inclined,
either front to back or vice versa. The rolls can be disposed
between any opposed wall surfaces in the bin or hopper. For
example, in a rectangularly shaped bin, shorter rolls can be
disposed between the opposed longer walls of the bin, or
longer rolls can be disposed between the opposed shorter
walls. In some applications, it may be advantageous to
position the rolls angularly with respect to the bin walls.
As shown in Figure 1 by the arrows on each of the rolls,
adjacent rolls rotate in opposite directions. This rotational
relationship is effective for grAn~ r and powdexous
materials; however, in some applications in which the flow
characteristics of the material are different, the rotational
pattern of the rolls may be different. While each of the
rolls may rotate at the same peripheral speed, it may be
advantageous to operate various rolls at different speeds.
The ease of flow, angle of repose, size, bulk density, and
other characteristics of the material stored in the bin will
affect the various alternate arrangements described herein.
In this regard, the rolls can each run at constant speeds or
at variable speeds.
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Figure 3 shows a pair of adjacent rolls 63 and 63a for
the discharge apparatus depicted in Figure 1 and 2. As shown,
the rolls may be adjacent, either in the horizontal or
vertical planes. While substantially cylindrical roll
surfaces are shown, it should be recognized that other shapes
can be used for the rolls. In Figure 4, oppositely directed,
generally frustoconically shaped rolls 64 and 64a are shown.
In Figure 5, interleaved staggered cylinders are shown on
adjacent rolls, with each roll including a central portion or
shaft 65 and larger cylindrical sections 66. Adjacent
sections 66 on a shaft 65 are spaced from each other to
accommodate interleaving of sections from adjacent shafts. In
Figure 6, a complimentary concave roll 67, and a convex roll
68 are shown. Each of the rolls is shown having knobs or
cleats 60 thereon. It should be recognized that the
arrangement pattern, proximity, shape, and length of the knobs
or cleats may vary, substantially depending on the
characteristics of the material being stored.
In Figures 7 through 10, a modified embodiment of the
rotating rolls is shown, in which each of the rolls includes a
plurality of radially extending projections or plates 70. The
plates 70 may extend continuously along the length of the
roll, or may be sporadically placed thereon, with plates of
adjacent rolls interleaving. The relatively long projections
or plates 70 are particularly suitable for applications in
which a single row of rolls is disposed along the bottom of
the bin. In Figures 7 and 8, four rolls 72, 74, 76, and 78
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are shown, with the projections or plates 70 extending the
length of each roll. Adjacent plates 70 on a single roll
define pocket areas 80 around the roll. As shown, each roll
includes 6 plates 70, defining 6 pockets on each roll. The
number of plates on each roll, and the number of pockets
defined thereby may vary. As shown in Figure 7, the rotor
pockets 80 of adjacent rolls interleave, such that a plate of
each adjacent roll will project partially into the pocket
defined by the other roll. In Figure 9, rolls 82 and 84 are
positioned such that only ,m; n; m~ 1 clearance is provided
between tips of the projections or plates 70, and the pockets
defined by the plates do not interleave. In Figure 10, rolls
90 and 92, at a slightly higher position, are shown disposed
with rolls 94 and 96, operating at a slightly higher position.
Again, the pockets 80 defined by the plates 70 of each roll
interleave with the pockets of adjacent rolls.
The rotational direction of the rolls of any of the
embodiments except the interleaved plate embodiments may be
the same or opposi~e. For discharging some types of material
subject to c~mp~cting, it is ad~lantageous to rotate all rolls
in the same direction, and periodically reverse the direction
of rotation to relieve pinching or wedging of material near
nonrotating surfaces, such as bin walls. The interleaved
plates or pockets must have adjacent rolls rotating in
opposite directions. As with the previous embodiments, the
rolls may be installed longitll~in~lly, perpendicularly, or
even angularly with respect to the longitudinal extent of the
hopper or bin. The axis of any of the rolls may be
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horizontal, or, as shown by phantom line 100 in Figure 8, the
rolls may be inclined, either front-to-back or back-to-front.
The rotational speed of the rotors in any of the
embodiments influences the discharge rate of material through
the apparatus. Where metering of material is required, the
interlaced rotors are most effective in controlling free-flow
and capturing regular, discrete volumes of material for
discharge. The interlaced pockets of rolls having long,
radially exte~ing plates 70 such as those shown in Figures 7
and 10 physically prevent the material from moving downwards
inside the hopper under action of gravity when the rolls are
not being turned. Thus, for granular, powdery or other
free-flowing materials, the interleaved pockets act as an
effective and accurate metering device.
As shown in Figure 2, an appropriate drive train 110 is
provided for rotating each of the rolls, with the drive train
110 being connected to a rotational drive so~rce 112. A
similar ~rive train 114 is shown in Figure 8 for rotating the
single row or rolls, also connected to a rotational drive
source 112. The type of drive train required, rotational
power source, and the like will be familiar to those versed in
the art, and will not be described in further detail herein.
In the use and operation of a discharge apparatus
embodying the present invention, material is loaded into the
bin or~hopper for storage, and falls, by gravity, to the
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bottom of the retention area 26. so long as the rolls of the
discharge apparatus are not rotated, the material will not
fall from the bin or hopper. The shape and arrangement of the
rolls, the type of knobs or projections used thereon, etc.,
are selected depending on the type and characteristics of
material being stored. The selection is such that the slope
of the path imposed by the rolls is less than the internal
angle of repose of the material, thereby inhibiting
gravitational flow from the hopper.
When it is desired to remove material from the bin or
hopper, the rotational drive source 12 is activated and the
drive train transfers power to each of the driven rolls of the
discharger. As the rolls are rotated, the material is
dislodged from the bottom of the retention area 26 and flows
between the rolls, through the discharge area 28, and into the
conveyor 16. The material is transported by the conveyor to
the desired location. When rotation of the rolls is stopped,
free-flow of material from the bin is obstructed by the rolls.
For interleaved pocket designs, essen~ially the entire bin
Gutlet is physically closed.
While particularly suitable for nonfree-flowing materials
such as wood chips, the present discharge apparatus will also
work well for granular or powder materials. Rotational speed
of the rolls influences the discharge rate of the apparatus,
and effective metering of the outflow of material from the bin
can be performed without causing compaction or bridging.
Essentially, all of the material freed from the retention area
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26 flows from the bin or hopper, and metering is effected by
the rate at which the rolls extract material from the
discharge area. With the apparatus covering a large area and
providing a bottom for the retention area in a substantially
unrestricted portion of the bin, bridging of the material
above the discharge apparatus is not a problem.
While several embodiments of a discharge apparatus
embodying the present invention have been shown and described
in detail herein, various changes may be made without
departing from the scope of the present invention, as defined
by the following claims.
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