CA 02239165 1998-OS-28
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Title
REFUSE BAG OPENER
Field of Invention
This invention relates to apparatus for opening
bags containing refuse and such apparatus incorporating
means to control the feed of bagged refuse to the bag
opener and/or feed of the bagged refuse to a pair of
vertically spaced apart counter rotating cylinders.
Backaround of Invention
Residential and commercial establishments bag
their refuse and this bagged refuse is normally collected
by packer trucks at regular intervals. Recycling programs
have brought into use blue boxes, carts, etc. and
historically municipalities have provided the blue boxes
and carts. The pick-up in many municipalities of
recyclable waste is a separate pick-up service.
The use of bags for collecting recyclables has
many advantages one being it removes the cost from the
municipality because bags are generally purchased by the
user. Also bags have other benefits as pick-up is cheaper,
less time consuming and simpler. Paper waste is also
protected by the bags. From a collection point of view
drivers can simply throw the bagged waste into the truck
and move on to the next location where bags are located.
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Containers (blue boxes) and carts on the other hand have to
be taken to the truck, emptied, and then returned to the
curb.
Studies have indicated that recovery rates of
recyclable material improves when bags are used in place of
blue boxes and containers. From a community point of view
bagged waste is tidier because it avoids having loose pages
of paper and newspapers blown about the neighbourhood as
often occurs when using blue boxes and containers.
Bags can be made of plastics material or paper.
The recyclable materials generally consist of various
metals such as aluminum and steel cans, plastic containers,
and glass bottles or jar as well as fibre material such as
newspapers, box board and corrugated paper. The organic
waste collected typically includes kitchen organic waste
and/or leaf and yard waste. Municipal solid waste includes
garbage or material generally destined for landfill. The
above materials and combinations thereof are referred to as
refuse for the purpose of this description.
Bagged refuse is taken to a handling facility and
at that facility it is necessary to have a mechanical bag
opener that not only opens the bag but also empties the
bag. It is desirable to have the open bag remain as a
unitary piece so that it can be readily separated from the
contents of the bag. This type of waste handling also has
a safety feature in that the contents of the bag are
displayed before being handled manually. Often there are
hazardous items such as syringes and broken glass in the
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waste material and these are visible instead of being
hidden inside the bag.
A desired characteristic of a mechanical bag
opener is that it must handle a wide range of material some
of which may be loose and the majority of which will be in
the bags. It must handle bags that have been compacted by
the packer pick-up trucks and a bag opener must also remove
the contents from the bag without shredding the bag into
many pieces. The bag opening machine should be able to
accept common items found in the waste stream without
damaging the machine some of the items for example may be
lawn chairs, bicycles, frying pans, children's large toys,
etc.
Mechanised bag openers are known and by way of
example reference may be had to the following United States
Patents: 5,639,202 issued June 17, 1997 to F. Roycraft;
5,567,106 issued October 22, 1996 to B. Gassner; 5,551,825
issued September 3, 1996 to J. Montgomery; 5,484,247 issued
January 16, 1996 to B. Clark, et al; 5,484,238 issued
January 16, 1996 to J. Bielagus; 5,433,577 issued July 18,
1995 to F. Roycraft; 5,415,515 issued May 16, 1995 to
Bielagus et al; 5,368,431 issued November 29, 1994 to E.
Willey; Canadian Patent documents 2,167,997 published
August 3, 1996, Campbell; et al; 2,167,772 published August
2, 1996, Nadarajah and Canadian Patent 2,010,489 issued
January 10, 1995 and issued to First Brands Industries
Corporation.
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Of the foregoing references United States patents
5,484,247 and 5,368,431 are considered the most closely
related to applicant's apparatus. The bag breaker
disclosed in the '247 patent has an in-feed hopper located
directly above the bite portion of two counter rotating
shafts that are of heavy construction. Because of the feed
being vertically downward and directly into the bite,
jamming can readily occur and/or brute force power will be
required to force the bagged material between the counter
rotating rollers. There is no means of controlling the
rate of feed to the power driven counter rotating shafts.
Also since brute force is used there can occur considerable
damage and breakage making later segregating and sorting
difficult particularly when glass is contained in the
bagged refuse. Another disadvantage of this apparatus is
that when winding occurs of the bagged contents on the
shaft, as it will, the material will be difficult to remove
because it will be wound upon the shafts with a very high
torque. A still further disadvantage is the difficulty of
accepting or passing large foreign objects between the
counter rotating rolls.
The apparatus disclosed in the '431 patent
includes an expensive and complicated bag opening
apparatus. The bagged refuse is fed by way of a first feed
conveyor onto a second input conveyor which discharges into
the bite of counter rotating bag slicer and a first paddle
wheel assembly. At this station the bags are sliced
transverse to the direction of travel of the bagged
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material. From there the sliced bag and contents thereof
are fed to a second pair of counter rotating rollers, the
bottom one of which slices the bags longitudinally and the
upper one is a second paddle which propels the contents.
The transverse and longitudinal slicing obviously will cut
the bag into many pieces making later sorting difficult.
From the second slicing station the open bags, and contents
removed therefrom, move to a further handling station by a
discharge conveyor. The first and second paddle wheel
assemblies are mounted on arms that pivot and use rigid
paddle blades.
Summary of Invention
The refuse bag opener of the present invention
includes controlled feeding of bagged waste to a pair of
vertically spaced counter rotating cylinders. The
apparatus includes a housing in which there is located
first and second cylinders that are disposed horizontally
in substantially parallel relation relative to one another.
The cylinders are spaced from one another in vertical
relation with the first cylinder having a plurality of
flexible members mounted thereon and radiating outwardly
therefrom. The second cylinder has a plurality of cutting
knives mounted thereon and radiating outwardly therefrom
and is located at a lower elevation than the first shaft.
The housing has an infeed hopper with an inlet thereto
located at a higher elevation than the second cylinder and
offset therefrom horizontally in a direction upstream from
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the second cylinder. The hopper has a bottom wall inclined
downwardly in a direction from said inlet towards the
second cylinder for directing bagged refuse towards the
lowermost one of the two cylinders. This arrangement
allows gravity to assist in feeding the bagged material to
counter rotating cylinders and by feeding the bagged
material toward the lowermost shaft it allows the knife
cylinder to slice and feed the bagged refuse to the bite of
the two counter rotating cylinders.
In the preferred embodiment of the invention
material flow sensor means is provided to controllably feed
the bagged refuse being supplied to the counter rotating
cylinders so as to allow for a continuous uniform flow of
refuse through the unit and which uniform feed is important
to downstream processing and efficiency. Also in the
preferred embodiment the lowermost cylinder, with the
knives thereon, is a relatively large diameter drum. This
overcomes the problem of having the bags and other material
wind around a shaft as is the case of prior art devices.
In the event bags (or other material) should become wound
around the drum it can readily and easily be removed
because of the drum's large diameter and relatively low
torque.
Power means is provided for driving the counter
rotating cylinders and such power means is preferably
controlled by a programmable logic controller (PLC). In a
preferred embodiment of the invention an auxiliary, short-
center, wide-belt feed conveyor is used to regulate the
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flow of material to the bite between the counter rotating
cylinders. Also a material or bagged refuse flow sensing
means is provided to automatically activate and deactivate
a feed conveyor that feeds bagged refuse to the infeed
hopper thereby ensuring an even feed of material
facilitating the most efficient later downstream handling
of the goods through an even feed. The auxiliary conveyor
speed and/or on-off operation thereof also can be
controlled by the PLC to also control the flow of material.
List of Drawincts
The invention is illustrated by way of example in
the accompanying drawings wherein:
Figure 1 is an oblique, partial schematic, of a
portion of a material recovery facility incorporating a bag
opening device of the present invention;
Figure 2 is a diagrammatic, vertical sectional,
view of a simplified form of applicant's bag opener;
Figure 3 is similar to Figure 2 but in which the
lower end of the infeed hopper is defined by a short-
center, wide-belt conveyor; and
Figure 4 is a vertical diagrammatic sectional
view taken essentially along line IV-IV of Figure 3;
Detailed Description
Referring to the drawings there is illustrated in
Figure 1 a portion of material recovery facility
incorporating a mechanical bag opener 20. A conveyor 10
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delivers bags 11 (containing refuse material and loose
refuse pieces 12, see Figures 2 and 3) from a self-
unloading hopper 13 to an inlet end of hopper 24 of the bag
opener 20.
The bag opener 20 of the present invention is a
compact, simple apparatus that can readily be incorporated
into an existing material recovery facility with little or
no modification. The bag opener 20 is a portable
integrated unit that can easily be relocated to accommodate
changing operations.
The infrastructure of a recovery facility may be
variously designed to include unloading hoppers, sorting
conveyors, transfer conveyors, platforms and sorting
stations as specific applications dictate. As illustrated
in Figure 1 the infrastructure of the apparatus includes a
sorting platform 14 and a control station 15. At the open
output end of the bag opener 20 there is a discharge
conveyor 60 that delivers the slit open bag and contents
thereof to a sorting station or stations (not shown).
Platform 14 provides an area for manual
presorting prior to the refuse being delivered to the inlet
end of the hopper 24. This manual presorting may or may
not be necessary depending upon the nature of the refuse
being delivered to the recovery facility.
At the control station 15 there is a control unit
80 which includes a programmable logic controller in a
housing having a control panel. The control unit and/or
control panel may be located at any convenient location or
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mounted, as shown, on a side panel that forms part of the
housing of the bag opener. The programmable logic
controller controls the sequential start-up and shut down
of the equipment as well as monitoring and controlling the
operation to provide an even through flow of material. The
PLC also provides an immediate response to an overload
condition.
The control unit includes a power disconnect as
well as selections of either manual or automatic operation.
The control unit also provides for variable speed control.
An infinitely variable speed control of motor speeds allow
for changing product mix and production rate. A forward
and reverse selection enables an operator to reverse
direction of cylinder rotation in the event of a jam.
There is also an emergency stop for immediate shut down of
the entire system as well as an overload alarm to signal
the operator of an overload condition.
In Figure 1 there is illustrated a power unit 81
comprising a motor driven hydraulic pump system in which
the hydraulic pump automatically adjusts pump output to
match system demand.
A hydraulic manifold is provided in a casing unit
82 mounted on the housing of the apparatus and the entire
operation is controlled by the programmable logic
controller in the control unit 80 which has the control
panel thereon.
The simplest form of applicant's bag opener is
illustrated in Figure 2 and the preferred more complete
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embodiment is illustrated in Figure 3. Referring to these
Figures the hopper 24 is defined by a downwardly sloped
bottom wall 21, a front wall 22 and a pair of spaced apart
opposite sidewalls 23 (only one being illustrated in
Figures 2 and 3). The bottom wall 21 slopes downwardly in
a direction from an open top inlet to the hopper towards a
knife cylinder 40. Behind the hopper front wall 22, and
above the knife cylinder 40, there is located a metering
cylinder 30. It is preferable and intended that the amount
of material fed to the knife cylinder 40 be one bag deep
and this is controlled in various ways as will be discussed
more fully hereinafter.
The downwardly sloped bottom wall 21 of the
hopper directs the bagged material to the knife cylinder 40
and sliding or rolling of the bags downward could simply be
the result of gravity assisted by vibration of the machine
during operation but preferably a controlled feed means is
provided. Vibration could be induced by suitable means
such as a vibrator attached to for example the hopper
bottom wall 21. As seen in Figure 2, loose items may fall
through gap 50 located between knife cylinder 40 and the
end of hopper bottom wall 21, with the loose items dropping
onto chute 51, which for example may be pivotally mounted
as at 52 and controllably moved by an apparatus such as
hydraulically actuated piston 53 towards and away from
knife cylinder 40 in a direction as indicated by double
arrow 54. As a result, gap 50 can be adjustably varied to
accommodate sizes of expected loose items.
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In a preferred form, however, and as illustrated
in Figure 3, there is an infeed conveyor 28 in the hopper.
This conveyor is automatically controlled by suitably
located sensors to automatically start, stop and/or run at
a suitable speed so as to feed the desired amount of
material to the bite between the knife cylinder 40 and the
metering cylinder 30.
The infeed conveyor 28 having a pair of end
return rollers on pulleys 27 is a short-center, wide- belt
conveyor and manufacturers of such have recognized
significant problems in tracking. A short-center, wide-
belt conveyor refers to conveyors where the ratio of the
center-to-center distance of the rollers or pulleys, over
the width of the belt, is less than 5. In the present
apparatus this ratio is significantly less than 1. In
order to accomplish proper tracking of the belt 35, a guide
and tension roller 70 is used on the inside surface of the
lower return flight of the belt 35. This tension roller
can be adjustably positioned by any known suitable roller
mounting means.
As previously mentioned it is intended that the
amount of material on the infeed conveyor 28 be only one
bag deep and if the depth exceeds this the extra material
trips a sensing arm 25 which in turn actuates a switch or
sensor device 26. This sensor can be used to control
operation and/or speed of the conveyor 10 and/or infeed
conveyor 28. Control of the conveyors) speed and/or
on/off is automatically done by the control unit 80 as
CA 02239165 2003-04-23
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reqmred to cldvance the rLecn;~s;~aY"'_,~ rna,-E?rlal t:c> ITla1_ntain a
one bag deptrl i_n a c:onti_nuous feed t:~ t:k~ze kn:if_n:~ cylinder
40.
The feed :Load ~;erlSir~.g ax~ra 25 may simply be
pivota:zll.y rnount.eca a;; at. <;~>~,. ,~c~ t k~~t.:. n,c»ement of the lower
end of the arm :Eorwax~dly, ~~auser~ x:,y too much advancing
bagged refuse causer~ act~.a~.t:.i.;_>rr c~ t:rie ,~-ensor or switch 26
to send a signal. to t_~ue ~'Lc:' f:~ox_ tLvE° latter to initiate
proper corrective act ion. 'flee fet~c:l =~ oad sensing means may
be the above described mec:~hanic~a:~. arrarzgemerrt of an arm (or
finger) actuatin~,~ a switch ~~r i.t ma-xy ~;~e an Plect:ric and/or
electronic sensing means or v:~ombin,:~t:ic:an thereof .
The infeed conveyor 28 =.nay Have cleats 29 on the
outer surface of belt 35 to assist in moving the material
toward the knife cylindez~.
With reference t.o Figure 3 , as tl.~ze infeed
conveyor 28 in the izoppez: feeds ruat:era.al toward the knife
cylinder, loose Ttern 1.~ r,lay fall t kzz-:~mcrla a gap BOA located
between the coruvc~yor '.?« almi t.iuc ~:m:;..fc cy~linde~:~ 4C~ and onto
2Q a chute 51A. G<ap ScJA is ~lctjust=~u by mowing conveyor 28
towards and away from krv~i..f'e c:~y:l. irn.;~er G30 as indicated by
dual. head arrow 54A. C'c;rr~reyor ~~8 <:~arz be moved back and
forth using any :5uitabl.e meal-IS Sm:u:,tl :~;.> guide ~>lc:~ts 55 far
re t.urrl rollers o:r_~ plr:Lley ,e'-7 G~nci c::~::vl.;:in~_~ bolt 56 to hold
the conveyor i.n i.ts :;elect cc:1 ~:~c~:,a.ti.c.>IU. Uap ~O.A t=::IU:> can be
adjustably varied t:o a~::v::ornrnc:~dat:~::r~ "~:~ffezerzt sizes of
expected loose i.t~.erns~ . ThE~ a:lcl j v.5t:.r~u,z~?t:: in~~y be c:~oxxE::
manual ly
and/or_ automatically.
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The metering cylinder 30 consists of a tubular
shaft 31 which is mounted parallel to the head shaft 27 of
the infeed conveyor 28 at a position above the knife
cylinder 40. The metering cylinder is driven by drive
means 34 (Figure 4) in a clock wise direction. This drive
means may be an electric motor, or a hydraulic motor as is
the case in this disclosed embodiment. Attached to the
tubular shaft is a series of paddle type flexible members
32 which perform several functions.
One function is to exert force/pressure on the
bags to ensure the bags contact slitting knives 42 on the
knife cylinder 40.
Another function is to set the length of time a
bag is in contact with the knife cylinder 40. This means
the metering cylinder 30 is either holding material back
until the knives have slit the bag and spilled the contents
onto the discharge conveyor 60, or the metering cylinder is
acting to advance the material.
Another function of the flexible members 32 is to
allow foreign oversized items through the machine by
flexing up to allow the object to pass.
It is also possible, in the event of an overload
condition or jam, for the direction of rotation of the
metering cylinder to be automatically or manually reversed.
This may rearrange the orientation of the jamming item such
that it may pass through on further forward rotation,
otherwise the jamming item must be removed manually.
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The rate of rotation of the metering cylinder 30
in conjunction with the speed of the infeed conveyor 28
acts to regulate the rate of production and, because the
design arrangement allows a continuous uniform material
flow through the unit, the rate of production is very
uniform (even measured over short time intervals). This
uniform feed to downstream processing is critical to
achieve overall production efficiencies.
The rate of rotation of the metering cylinder 30,
as well as that of the knife cylinder 40 and the speed of
the infeed conveyor 28 can all be varied independently or
proportionally by either manual means or the electronic
means contained in control panel 80. This type of control
is easily understood by anyone skilled in basic machine
design and therefore further details of the same are not
further disclosed herein.
The knife cylinder 40 is normally rotated in a
counter clock wise direction at a rate which is variable
and faster than the metering cylinder 30.
The knife cylinder 40 is mounted parallel to the
metering cylinder 30 at a position therebelow and with its
axis of rotation parallel to that of the infeed conveyor
head shaft or roller 27.
The knife cylinder 40 comprises a shaft 43 (see
Figures 3 and 4) on which a series of thin circular plates
or discs 45 are attached concentric and perpendicular to
the shaft 43. Spacing rings 44, concentric with the shaft
43, are fitted between each circular plate. The spacing
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rings determine the distance between each circular plate
and also stop material from winding onto the shaft 43. The
spacing rings are of large diameter, relative to that of
shaft 43, and thus act to prevent material from winding on
the cylinder.
The width of the spacing rings 44 may be designed
to meet requirements depending on the expected size of bags
to be opened.
The circular plates or discs 45 can act
themselves as a rotary slitting knife or replaceable knife
sections 42 can be mounted on the periphery of the circular
plate 45. The circular plate 45, or the replaceable knife
sections 42, as the case may be, can utilize various knife
profile designs, depending on the expected contents of the
bags. The individual knives 42 would be suitably spaced
circumferentially around and longitudinally along the
cylinder 40.
As previously described, the knife cylinder rate
of rotation can be varied independently or proportionately
with the rate of rotation of the metering cylinder or the
speed of the hopper feed conveyor.
The knife cylinder 40 can also be operated in a
reverse or clockwise direction, the direction of rotation
can be set by manual control or by automatic operation.
Reversing the direction of rotation of the knife
cylinder may rearrange material which has caused a jam or
overload. When the knife cylinder is reset in the forward
(counter clockwise) direction, the jamming item may pass
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through. This forward, reverse, forward operation may be
controlled manually or automatically.
If this does not clear a jamming condition, then
the jamming item must be removed manually.
The relative spacing between the knife cylinder
40 and metering cylinder 30 can be designed to meet
conditions depending on the expected bag size and contents.
One or the other or both of bearing supports 31A and 43A
(Figure 4) of respective shafts 31 and 43 may be mounted on
track style sliders so that the mentioned relative spacing
may be adjusted manually and/or automatically.
By raising the metering drum significantly away
from the knife drum, foreign jamming objects can be passed
through the Bag Opener and again such raising may be manual
but preferably it is automatic.
Once a bag has passed between the metering
cylinder 30 and the knife cylinder 40, the bag will have
been slit sufficiently to allow the contents to spill out
onto the discharge conveyor 60 on which there may be loose
material deposited from the chute 51 or 51A.
The bag is typically left in one piece for
removal. Removing the bag from amongst the contents is
typically done manually by sorting personnel.
The foregoing described feed and control of feed
to the bite between the knife cylinder 40 and the metering
cylinder 30 provides a relatively even through flow of
material. This is despite the fact that the material
arrives having been compacted and in various states. The
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bagged refuse is generally collected in a compactor style
truck where the bags are packed into a closed container.
This packing along with the nature of the bagged material
causes the bags to nest together. The feed conveyor 10 is
controlled by the level of material in the hopper 24 by way
of the feed speed sensor 25. On/off operation of the
conveyor 10 and/or control of the speed thereof through
actuation of sensor or switch 26 and/or control of the
infeed conveyor 28 allows the clumps of bags to be
separated apart. The infeed conveyor 28 then presents to
the bag opener counter rotating drums separated bags which
are significantly easier for the metering cylinder 30 and
knife cylinder 40 to get hold of and perform the slicing
and emptying function.
The present equipment through extensive
development and testing has proven effective. The
hydraulic drive system provides for a wide range of speed
control and is easy to match input horsepower to required
horsepower. There is economical overload protection and it
is easy to add peripheral equipment drives. Electric motor
drives in some instances, however, may be preferred as it
simplifies design and reduces cost.
The equipment has been found suited to handling
foreign and oversized objects. Shaft winding of bags
and/or material that has been an issue with prior equipment
has been minimized. Glass breakage, considered a
significant issue in waste handling, is minimized by the
use of flexible members 32 on the metering cylinder 30.
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While a paddle arrangement is preferred with flexible web
like members extending parallel to the rotating shaft and
radiating outwardly therefrom it would be possible to use
separate and individual flexible members spaced
circumferentially and longitudinally along the shaft.
