Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS AND APPARATUS FOR HIGH-SPEED
FILLING OF COMPOSITE CIGARETTE FILTERS
Background of the Invention
This invention relates to a process and apparatus for use in the
manufacturing of cigarette filters. More particularly, this invention relates
to a process
and an apparatus for high-speed filling of particulate matter in discrete
cavities defined
by adjacent individual filter plugs during the filter assembly operation.
In composite filters having cavities filled with particulate matter, the fill
percentage of the cavities is very important. This is because, as the
cigarette is placed
into the mouth, it lies in a substantially horizontal plane. Thus, gravity
draws the
particulate matter down away from the top of the cavity. This creates an
unprotected,
unfiltered bypass above the particulate matter that does not inhibit the flow
of smoke.
The affect that this bypass has on the filtering capacity of a filter is not
yet appreciated
but can possibly be disproportionately large compared to the linear proportion
of the
width of the bypass to the width of the filter element. In fact, fluid flow
principals dictate
that fluid prefers to flow along a path of least resistance, thus indicating
that the
filtering efficiency of the particulate matter may be greatly reduced by the
presence of
any such pass through portion.
Referring to U.S. Patent No 3,312,152 to Williamson, an apparatus is
described which attempts to fill the filter cavities. The Williamson apparatus
transfers
particulate material into discrete spaces between filter plugs. However, the
speed of
operation of the apparatus is limited due to inefficiency of relying on
gravity alone to fill
the rapidly passing cavities.
A prior art machine such as that described in U.S. Pat. No. 4,063,494
and 5,908,030, includes gravity-fed, wheel-shaped receiving magazines that
receive
filter segments laid out adjacent to one another in a spaced apart
relationship on a
paper carrier strip. The loaded strip is then brought into an assembly or
guide channel
and toward a filling area where the paper is formed on wheels into a receiving
trough.
As described in U.S. Pat. No. 4,015,514 to Nichols, a vacuum is applied across
adjacent filter segments in an effort to promote the filling of the cavity.
However,
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because both the spacing of the segments varies and the density of the
cellulose
acetate filters varies, it is impossible to fill the cavities with any
consistency. This
means that in order to ensure a minimum percentage of filling, the process
must be
set up to significantly overfill the cavities above this target level. The
industry has
compensated for this by not demanding a high fill percentage. In this manner,
the
process tolerates a very high variance provided that the target fill
percentage is
sufficiently high.
Further, despite the fact that the fill percentage demanded by industry is
low, it is desirable to completely fill the cavity with granules. As explained
above, this
1o is because it has been shown that a cavity that is not completely filled
allows smoke to
bypass the particulate filling, thus failing to permit the particulate to
remove the
undesirable compounds in the smoke.
Further, overfill of the cavity or the escape of the particulate from the
cavities may cause the particulate to adhere to the outer garniture or the
paper carrier
strip and thus become embedded near the surface of the final product, leaving
an
unsightly stain or mark.
What is needed is a process of completely filling filter cavities in a
commercially practicable manner. More specifically, what is needed is a
process and
an apparatus to rapidly fill active charcoal filter cavities at a rate
exceeding 200 m/min.
Summary of the Invention
A process of manufacturing composite filter stock is provided that
includes several steps:
a) depositing fibrous filter segments on a carrying strip in a spaced apart
relationship, thus defining cavities between adjacent filter segments;
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b) feeding the carrying strip with the deposited filter segments along a path
of
travel into an elongated support chamber with substantially surrounds the
circumference of the filter segment-retaining carrier strip and which leaves a
narrow fill opening opposite a particulate filling opening of a filling
assembly,
the narrow fill opening being elongated along the direction of motion of the
carrying strip;
c) concurrently applying a vacuum or suction adjacent the narrow opening, the
suction thus increasing a downward momentum of a gravity feed stream of
particulate matter and vacuuming away loose particulate matter;
d) concurrently filling the cavities with the particulate matter over a length
corresponding to a predetermined path of travel of the carrying strip; and
e) applying a sealing portion which encapsulates the filter segments and
particulate matter.
So, in a first step, a paper carrier strip or garniture feeds along a
conveyor. Along
one edge of the carrier strip, the paper is folded back against itself.
Fibrous filter segments
are then deposited on the carrying strip in spaced apart intervals. The
spacing defines
cavities between adjacent filter segments. The carrier strip with the
deposited filter
segments is fed along a path of travel into an elongated guide or support
chamber that
substantially surrounds the circumference of the paper-enveloped segments and
which
leaves a narrow fill opening opposite a particulate filling opening that is
elongated in the
direction of motion of the carrying strip. Suction or a vacuum is concurrently
applied
adjacent the narrow opening, the suction increasing a downward momentum of a
gravity
feed stream of particulate matter and concurrently vacuuming away loose
particulate
matter. The cavities are concurrently filled with the particulate matter over
a length
corresponding to a predetermined path of travel of the carrying strip. The
folded over edge
is then unfolded and adhered to seal the fill opening. Alternately, a sealing
strip seals the
opening, thus encapsulating the filter segments and particulate matter. The
filter stock is
then cut to length, the cutting being registered to create discrete composite
filter segments.
In another feature, filter cavities may be rapidly and completely filled with
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particulate matter such as charcoal.
In another feature, the density of activated charcoal is controlled through
the
introduction of an inactive filler material.
According to one aspect, the present invention relates to a process of
manufacturing composite filter stock comprising the steps of: depositing
fibrous
filter segments on a carrying strip in a spaced apart relationship, thus
defining
cavities between adjacent filter segments; feeding the carrying strip with the
deposited filter segments along a path of travel into an elongated support
chamber
which substantially surrounds the circumference of the filter segment-
retaining
carrier strip and which leaves a narrow fill opening opposite a particulate
filling
opening of a filling assembly applying a vacuum or suction, filling the
cavities and
applying a sealing portion which encapsulates the filter segments and
particulate;
wherein the particulate filling opening concurrently facing several cavities
is
elongated along the direction of motion of the carrying strip over a length
corresponding to a predetermined path of travel of the carrying strip; and
concurrently applying the vacuum or suction adjacent the narrow fill opening
the
suction thus increasing a downward momentum of a gravity feed stream of
particulate matter and vacuuming away loose particulate matter; concurrently
filling
the cavities with the particulate matter over a length corresponding to a
predetermined path of travel of the carrying strip.
Brief Description of the Drawings
FIG. I is a perspective view of a partially assembled filter segment of the
invention.
FIG. 2 is a schematic diagram of an apparatus capable of practicing the
invention.
FIG. 3a is a perspective view of a particulate matter filling assembly of the
invention.
FIG. 3b is a perspective, staggered cross-sectional view of the particulate
matter
filling assembly, taken substantially along plane A of FIG. 3a.
FIG. 3c is a front view of the cross-section of FIG. 3b.
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FIG. 3d is a front view of a cross-sectional view of the particulate matter
filling
assembly, taken along plane B of FIG. 3a.
FIG. 3e is a perspective, cross-sectional view of the assembly of FIG. 3a,
taken
along plane C, shown in FIG. 3d.
FIG. 4 is a flow chart of the process of the invention.
Detailed Description of the Preferred Embodiment
An apparatus 10 and a process 12 of manufacturing composite filter stock 14
having cavities 16 (best shown in FIG. 2) filled with particulate matter 20 is
provided. Referring now to FIG. 1, the cavity 20 is defined between two filter
plugs 22, such as are traditionally used in making cellulose acetate filters.
The
particulate matter 20 is preferably activated charcoal 24 but may be any other
suitable active or inactive component, including sepiolite, silica gel, and
nonactivated carbon. These particulate matter 20 can also include aromatic
particulate.
The apparatus 10 capable of carrying out the process 12 is substantially that
as
shown in U.S. Pat. No. 4,223,597,
4a
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wherein the process of filling, the filling part 12 of the `597 patent, and
the receiving
fixturing are improved.
Referring now to FIG. 2, the apparatus 10 is shown in more detail. The
apparatus
5 10 includes a garniture or tool body 26, a strip conveyor 30, a funnel 32, a
conveyor 34, a
hopper 36 containing solid material 20, a separator chamber 40, and a vacuum
power unit
42, connected together as described below with associated vacuum lines (e.g.,
44, 46) and
other connections.
In operation, a vacuum power unit 42 creates a vacuum in the separator chamber
40
by expelling air through exit port 92. The cyclone separator and filter 56
filters dust from
the air in which particulate material 20 is suspended, having been sucked
through the
vacuum lines 44 from the filling assembly 64. This vacuum action evacuates any
particulate that may be loose within the filling assembly 64, via evacuation
slits 60
disposed on either side of the opening 62 to the cavities 16. Particulate
material 20 in the
air falls to the bottom of the separation chamber 40 and finds its way into
the hopper 36,
through the sealed rotary air lock 52. The rotary air lock 52 allows the
separator chamber
40 and the hopper 36 to have substantially differing pressures in which the
hopper's
pressure is substantially ambient. A feed line 54 provides the hopper with
additional solid
material 20 as needed. The hopper 36 deposits particulate matter 20 on the
conveyor belt
34. The conveyor belt 34 conveys the solid material 20 from the hopper 36 to
an area
above the funnel 32 and then, into the funnel. 32. The funnel-shaped entry 33
of the funnel
32, having a wide opening gradually narrowing along the direction of flow
provokes
acceleration of the particulate matter 20.
The garniture 26 and strip conveyor 30 guide and position the strip 50 (shown
in
FIG. 3a) in the filling assembly 64. The funnel 32 directs solid material 20
into the cavities
16. The solid material 20 is gravity fed from the conveyer belt 34 with, to a
limited extent,
vacuum assistance (via evacuation slits 60).
Referring now to FIGs. 3a - 3e, the filling assembly 64 of the apparatus 10 is
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shown. For clarity, cross-sections A and B are taken transverse to the line of
motion and
cross-section C is taken along the line of motion of the filter assembly 14.
The filling assembly 64 includes a lower garniture 66 and an upper garniture
having
a left portion 70 and a right portion 72. A manifold 74 covers the garniture
26 and provides
a mounting for the funnel 32, which has two end caps 76 and 80. The manifold
74 defines
vacuum passageways including the evaluation slit 60, channels 82 and 84, and
exit ports 86
and 90. The exit ports 86 and 90 connect to vacuum lines 44. The vacuum helps
draw the
particles 20 into each cavity 16 while at the same time sucking away particles
that fall to
either side of the opening 62 and on the exposed portion of the filter segment
22.
Referring now to FIG. 4, the process 12 includes several steps. In a first
step 100, a
paper ribbon or carrier strip 50 feeds along the strip conveyor 30. Along one
edge 102 of
the carrier strip 50, the paper is folded back against itself, forming a fold
104. In a second
step 106, fibrous filter segments 22 are deposited on the carrying strip 50 in
spaced apart
intervals. The spacing between filter segments 22 defines cavities 16 between
adjacent
filter segments. In a third step 108, the carrier strip 50 together with the
deposited filter
segments 22 are fed along a path 110 of travel into the garniture 26 which
substantially
surrounds the circumference of the segments 22 and which leaves a narrow fill
opening 62,
generally between 2 and 3 mm in width, opposite a particulate filling opening
112. The
filling opening 112 is elongated along the direction of motion 110, indicated
by arrow Y in
FIG. 3e, of the carrying strip 50.
In a fourth step 114, suction or a vacuum is concurrently applied to the
evacuation
slits 60 on opposite sides adjacent the narrow opening 62, the suction, thus
increasing a
downward momentum of a gravity fed, vacuum-assisted stream of particulate
matter 20
and vacuuming away loose particulate matter 20 (also known as overflow
matter). This
also helps prevent particles 20 from becoming laminated between an overlap
area 116 (on
which the fold 104 will adhere) and the fold when the fold 104 is brought back
across the
narrow opening 62 to seal the opening. Such trapped particulate matter 20 is
considered a
product defect and is reason to reject a production run. In a fifth optional
step 118, the
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vacuumed away matter is then recycled, being repressurized as it passes
through the airlock
52 after which it is deposited in the hopper 36. Thus, such defects are to be
avoided.
In a sixth step 120, the cavities 16 are concurrently filled with the
particulate matter
20 over a predetermined length L (shown in FIG. 3e) corresponding to the path
110 of
travel of the carrying strip 50. In a seventh step 122, the folded-over edge
104 is then
unfolded and adhered to seal the fill opening 62. Alternately, a sealing strip
as described in
U.S. Pat. No. 4,225,597 seals the opening 62, thus encapsulating the filter
segments 22 and
particulate matter 20, creating a filter stock that exits the garniture 26. In
an eighth step
124, the filter stock is then cut to length, the cutting being registered so
as to cut through
the filter segments 22, thus creating discrete composite filter segments which
may be
assembled together with a paper and tobacco to form a cigarette.
Experimentation has shown that, using the process 12 and apparatus 10 of the
invention, the fill percentage remains directly proportional to the flow rate
of particulate
matter, up to a fill percentage of 95%. Thus, the process 12 permits the easy
and accurate
adjustment of the fill percentage to the demands of a customer.
In an alternate embodiment of the invention, the particulate matter 20 is made
up of
active matter (active charcoal 24) and inactive matter (e.g., an inert filler
25). The
granulate shape, whether for active or inactive particulate matter, is very
important as this
characteristic affects the speed at which it can be accelerated toward the
narrow opening of
the cavity. In this manner, the amount of charcoal 24 in the filter can be
varied and
optimized, based on experimentation. Further, the affect that the active
matter 24 has on
the taste and the filtering properties of the cigarette can be controlled as
well. Controlling
the amount of active charcoal 24 in this manner (by adding filler) is
necessary because it is
not possible to reduce the size of the cavity 16, due to the variation in
length of the opening
62 between filter elements 22 (i.e., the speed of the overall assembly
operation is such that
the filter elements 22 cannot be spaced apart on the carrier strip 50 very
accurately and thus
vary from an ideal relative position by as much as 0.5 inm in either
direction). Further,
active charcoal 24, the most widely used and available active filler, is only
available in a
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single state. The charcoal 24 cannot be ordered at an economical price in a
state that is
50% active, for example. Still further, the percentage of active vs. inactive
matter can be
precisely controlled by pre-mixing the active and inactive matter prior to
placing the
mixture in the particulate hopper 40 of the apparatus 10.
In an advantage of the invention, it is possible to fill 250 m/min. or five
times faster
than any competitive process that fully fills the cavity.
In another advantage of the invention, it is now possible, as a function of
the feed
rate and length of the elongated filling opening, to completely fill filter
cavities (up to
100% filled is possible).
Multiple variations and modifications are possible in the embodiments of the
invention described here. Although certain illustrative embodiments of the
invention have
been shown and described here, a wide range of modifications, changes, and
substitutions
is contemplated in the foregoing disclosure. In some instances, some features
of the present
invention may be employed without a corresponding use of the other features.
Accordingly, it is appropriate that the foregoing description be construed
broadly and
understood as being given by way of illustration and example only, the spirit
and scope of
the invention being limited only by the appended claims.
