U.S. patent application number 12/671204 was filed with the patent office on 2010-11-18 for method and apparatus for forming tobacco rods.
Invention is credited to Andrew Jonathan Bray, Karl Kaljura.
Application Number | 20100288292 12/671204 |
Document ID | / |
Family ID | 38529107 |
Filed Date | 2010-11-18 |
United States Patent
Application |
20100288292 |
Kind Code |
A1 |
Kaljura; Karl ; et
al. |
November 18, 2010 |
Method and Apparatus for Forming Tobacco Rods
Abstract
A method of forming tobacco rods comprises providing an endless
bead of tobacco, creating regularly spaced apart gaps (14) with no
tobacco along the length of the bead, wrapping the bead in an
endless length of paper wrapper (16), and cutting through the paper
wrapper where it overlays the gaps in order to divide the wrapped
bead into individual tobacco rods. The gaps may be created using an
ecreteur with trimmer discs configured to trim away the full width
of the tobacco rod (10), or by using a rotating screw thread
extending into the tobacco.
Inventors: |
Kaljura; Karl; (London,
GB) ; Bray; Andrew Jonathan; (London, GB) |
Correspondence
Address: |
CHADBOURNE & PARKE LLP
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
38529107 |
Appl. No.: |
12/671204 |
Filed: |
July 25, 2008 |
PCT Filed: |
July 25, 2008 |
PCT NO: |
PCT/EP08/59812 |
371 Date: |
June 25, 2010 |
Current U.S.
Class: |
131/70 |
Current CPC
Class: |
A24C 5/54 20130101; A24C
5/1814 20130101 |
Class at
Publication: |
131/70 |
International
Class: |
A24C 5/00 20060101
A24C005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2007 |
GB |
0714972.7 |
Claims
1. A method of forming tobacco rods suitable for the manufacture of
tobacco products with at least one closed end, the method
comprising: providing an endless bead of tobacco; creating
tobacco-less gaps in the bead, the gaps regularly spaced apart
along the bead; wrapping the bead in an endless length of paper
wrapper; and dividing the wrapped bead into tobacco rods by cutting
through the paper wrapper where it overlays the gaps.
2. The method according to claim 1, wherein: each gap has a length
equal to twice a length of paper wrapper required for subsequent
folding over the tobacco; and dividing the wrapped bead comprises
cutting through the paper wrapper at the longitudinal mid-point of
each gap.
3. The method according to claim 2, wherein the gaps are spaced
apart by a distance equal to twice a length of tobacco intended for
smoking articles to be made from the tobacco rods.
4. The method according to claim 3, further comprising dividing the
tobacco rods longitudinally in half by cutting through at the
longitudinal mid-point of each tobacco rod.
5. The method according to claim 2, in which the gaps are spaced
apart by a distance equal to a length of tobacco intended for
smoking articles to be made from the tobacco rods.
6. The method according to claim 1, wherein: each gap has a length
equal to a length of paper wrapper required for subsequent folding
over the tobacco; the gaps are spaced apart by a distance equal to
a length of tobacco intended for smoking articles to be made from
the tobacco rods; and dividing the wrapped bead comprises cutting
through the paper wrapper substantially flush with one end of each
gap.
7. The method according to claim 1, wherein creating the
tobacco-less gaps in the bead comprises removing tobacco from the
bead.
8. The method according to claim 7, wherein removing the tobacco
from the bead comprises trimming away the full width of the tobacco
in the bead over the length of each gap using an ecreteur.
9. The method according to claim 1, wherein creating the
tobacco-less gaps in the bead comprises dividing the bead into
longitudinal portions of tobacco and moving the portions apart.
10. The method according to claim 9, wherein dividing the bead and
moving the portions of tobacco apart comprises: bringing a screw
thread which is rotating about an axis parallel to the length of
the bead into contact with the bead while the bead is traveling
longitudinally, the screw thread having a thread with a thickness
which increases with distance along the screw thread.
11. The method according to claim 10, wherein the screw thread has
a thread which commences from a point at the leading end of the
screw thread, the thread having a radius that increases with
distance along the screw thread from a point over at least part of
the length of the screw thread.
12. The method according to claim 10, in which the screw thread has
a thread which commences from a leading edge arranged substantially
along a radius of the thread, the thread having a substantially
constant radius.
13. The method according to claim 9, wherein dividing the bead and
moving the portions of tobacco apart comprises: moving at least one
rotating disc into and out of the bead, the disc rotating about an
axis parallel to the bead and having a thickness that increases
from the edge to the centre of the disc.
14. An apparatus for forming tobacco rods suitable for manufacture
of tobacco products with at least one closed end, the apparatus
comprising: a conveying device for supporting and conveying an
endless bead of tobacco; a tobacco spacing device operable to
create regularly spaced apart tobacco-less gaps in the bead; a
garniture and a paper wrapper supply arranged to receive the bead
after the creation of the gaps and wrap the bead in an endless
length of the paper wrapper; and a cutter operable to divide the
wrapped bead into tobacco rods by cutting through the paper wrapper
where it overlays the gaps.
15. The apparatus according to claim 14, wherein the tobacco
spacing device creates the gaps by removing tobacco from the
bead.
16. The apparatus according to claim 15, wherein the tobacco
spacing device comprises an ecreteur having at least one trimmer
disc with a circumference height profile configured to trim away
the full width of tobacco in the bead over the length of each
gap.
17. The apparatus according to claim 14, wherein the tobacco
spacing device creates the gaps by dividing the bead into
longitudinal portions of tobacco and moving the portions apart.
18. The apparatus according to claim 17, wherein the tobacco
spacing device comprises a screw thread rotatable about an axis
parallel to the length of the bead such that a thread of the screw
thread passes through the bead as it is carried by the conveying
device, the thread with a thickness which increases with distance
along the screw thread.
19. The apparatus according to claim 18, wherein the screw thread
has a thread which commences from a point at the leading end of the
screw thread, the thread having a radius that increases with
distance along the screw thread from the point over at least part
of the length of the screw thread.
20. The apparatus according to claim 18, wherein the screw thread
has a thread which commences from a leading edge arranged
substantially along a radius of the thread, the thread having a
substantially constant radius.
21. The apparatus according to claim 17, wherein the tobacco
spacing device comprises at least one disc rotatable about an axis
parallel to the bead and movable into and out of the bead while
rotating, the disc having a thickness that increases from the edge
to the centre of the disc.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method and apparatus for
forming tobacco rods, where the tobacco rods are suitable for the
manufacture of smoking articles with closed ends.
[0002] Manufactured smoking articles such as cigarettes
conventionally comprise a tobacco rod having a wrapping of
cigarette paper, and a filter attached to the tobacco rod by a
tipping paper, although plain cigarettes, lacking a filter, are
also available. In either case, the end of the cigarette which is
intended to be lit is often open, so that the tobacco inside the
cigarette paper is exposed. This allows leakage or spillage of
tobacco from the cigarette, and also allows contaminants and
foreign bodies to enter the tobacco.
[0003] To address this, it has been previously proposed to close
one or both ends of a cigarette by folding or otherwise
manipulating a portion of the cigarette paper that extends beyond
the tobacco rod. For this, it is necessary to arrange for a tobacco
rod of a length shorter than the surrounding wrapper. It is usual
in cigarette manufacturing for an endless length or bead of tobacco
to be wrapped in an endless length of cigarette paper, with the
result being cut through at intervals to form individual rods. This
necessarily produces rods in which the tobacco and the paper are of
equal length. Hence, alternative techniques are needed to produce
tobacco rods with a paper overhang that can be folded to close the
end(s) of the cigarette.
[0004] For example, United Kingdom patent applications GB 0622687.2
and GB0703785.6 filed on 14 Nov. 2006 and 27 Feb. 2007, both
entitled "Smoking article with closed end and methods and apparatus
for manufacture thereof` describe adhering an additional portion of
foldable paper around the end of a tobacco rod to create an
overhanging part for folding over to form a closed end. Older
examples include U.S. Pat. No. 1,164,118, which describes a
cigarette-making machine that forms a tube from an individual
cigarette paper, closes one end of the tube, partially fills the
tube with tobacco, and then closes the other end. U.S. Pat. No.
501,498 describes a machine that wraps an individual cigarette
paper around an individual length of tobacco, compresses the
tobacco from both ends to make paper overhangs for folding, and
then closes each end by folding. These older approaches are not
well-suited to modem cigarette manufacturing techniques,
however.
[0005] Another technique is to produce a completed conventional
smoking article that has a longer than usual length of tobacco rod.
The filter end of the smoking article is placed vertically on a
vibrating surface, or tapped down. This settles the tobacco further
down into the enclosing wrapper, leaving a free end of the wrapper
than can be folded over for a closed end. This is potentially
disadvantageous, however. Tobacco typically comprises a mixture of
various smokable materials, and these tend to settle at different
depths after vibration or tapping, giving a non-uniform composition
to the tobacco rod.
SUMMARY OF THE INVENTION
[0006] Accordingly, a first aspect of the present invention is
directed to a method of forming tobacco rods, comprising: providing
an endless bead of tobacco; creating tobacco-less gaps in the bead,
the gaps regularly spaced apart along the bead; wrapping the bead
in an endless length of paper wrapper; and dividing the wrapped
bead into tobacco rods by cutting through the paper wrapper where
it overlays the gaps.
[0007] This results in tobacco rods that have an overhanging
portion of paper at one or both ends (depending on the position of
the cuts) that can be folded inwards over the tobacco to close the
end(s) of the completed smoking article. The method includes the
conventional steps for making tobacco rods, plus an extra stage of
creating the gaps in the tobacco bead. The extra stage can be
readily incorporated into standard production, so existing
production lines and methods can be easily adapted to implement the
present invention. Moreover, creation of the gaps can be performed
rapidly and simply with non-complex equipment and without
interruption of the travel of the tobacco through the production
process, so production times can be as fast, or nearly as fast, as
the production of conventional tobacco rods.
[0008] In some embodiments, the method is implemented such that
each gap has a length equal to twice a length of paper wrapper
required for subsequent folding over the tobacco, and dividing the
wrapped bead comprises cutting through the paper wrapper at the
longitudinal mid-point of each gap. If the gaps are spaced apart by
a distance equal to twice a length of tobacco intended for smoking
articles to be made from the tobacco rods, double-length tobacco
rods can be formed. Each double length rod comprises two single
length rods joined back-to-back, with the overhanging paper for
each at the ends of the double-length rod. The method may then
further comprise dividing the tobacco rods longitudinally in half
by cutting through at the longitudinal mid-point of each tobacco
rod, to produce single length rods each comprising one length of
tobacco and a paper overhang at one end. These can be used to
produce a filter-tipped cigarette with a closed tobacco end.
[0009] Alternatively, the gaps may be spaced apart by a distance
equal to a length of tobacco intended for smoking articles to be
made from the tobacco rods. Thus, the tobacco between the gaps is
the length required for a single smoking article, which produces
tobacco rods with overhanging paper at both ends, from which a
filterless cigarette with two closed ends can be made.
[0010] As an alternative for producing single length rods with
overhanging paper at one end only, each gap may have a length equal
to a length of paper wrapper required for subsequent folding over
the tobacco, the gaps may be spaced apart by a distance equal to a
length of tobacco intended for smoking articles to be made from the
tobacco rods, and dividing the wrapped bead may comprise cutting
through the paper wrapper substantially flush with one end of each
gap.
[0011] Creating the tobacco-less gaps in the bead may comprise
removing tobacco from the bead. Any technique suitable for this may
be employed. For example, removing tobacco from the bead may
comprise trimming away the full width of tobacco in the bead over
the length of each gap using an ecreteur. Ecreteurs are well-known
for trimming tobacco from beads to achieve a uniform thickness of
tobacco. Hence, no complex modification to a production line is
needed to implement this embodiment. An additional ecreteur may be
added for creating gaps in the bead, or more simply, an existing
ecreteur may be modified or replaced to create the gaps in addition
to regular tobacco trimming.
[0012] Alternatively, creating the tobacco-less gaps in the bead
may comprise dividing the bead into longitudinal portions of
tobacco and moving the portions apart. Again, any suitable
technique may be used for this. For example, dividing the bead and
moving the portions of tobacco apart may comprise bringing a screw
thread which is rotating about an axis parallel to the length of
the bead into contact with the bead while the bead is travelling
longitudinally, the screw thread having a thread with a thickness
which increases with distance along the screw thread. Use of a
screw thread does not interfere with the forward travel of the
tobacco bead along a production line, because a screw which is
stationary except for its rotation will move the tobacco
longitudinally, like water pulled up by an Archimedes screw. The
screw thread may be configured in various ways. For example, the
screw thread may have a thread which commences from a point at the
leading end of the screw thread, the thread having a radius that
increases with distance along the screw thread from the point over
at least part of the length of the screw thread. Or, the screw
thread may have a thread which commences from a leading edge
arranged substantially along a radius of the thread, the thread
having a substantially constant radius.
[0013] In a further example, dividing the bead and moving the
portions of tobacco apart may comprise moving at least one rotating
disc into and out of the bead, the disc rotating about an axis
parallel to the bead and having a thickness that increases from the
edge to the centre of the disc. This technique may be found more
complex to implement than a screw thread as regards processing of a
moving tobacco bead. However, rotating discs configured in this way
are advantageous in that a single disc or assembly of discs can be
used to create gaps of different length.
[0014] A second aspect of the present invention is directed to
apparatus for forming tobacco rods, comprising: a conveying device
for supporting and conveying an endless bead of tobacco; a tobacco
spacing device operable to create regularly spaced apart
tobacco-less gaps in the bead; a garniture and a paper wrapper
supply arranged to receive the bead after creation of the gaps and
wrap the bead in an endless length of paper wrapper; and a cutter
operable to divide the wrapped bead into tobacco rods by cutting
through the paper wrapper where it overlays the gaps.
[0015] The tobacco spacing device may create the gaps by removing
tobacco from the bead. For example the device may be an ecreteur
having at least one trimmer disc with a circumference height
profile configured to trim away the full width of tobacco in the
bead over the length of each gap.
[0016] Alternatively, the tobacco spacing device may create the
gaps by dividing the bead into longitudinal portions of tobacco and
moving the portions apart. Such a device may comprise a screw
thread rotatable about an axis parallel to the length of the bead
such that the thread of the screw thread passes through the bead as
it is carried by the conveying device, the thread with a thickness
which increases with distance along the screw thread. The screw
thread may have a thread which commences from a point at the
leading end of the screw thread, the thread having a radius that
increases with distance along the screw thread from the point over
at least part of the length of the screw thread. Alternatively, the
screw thread may have a thread which commences from a leading edge
arranged substantially along a radius of the thread, the thread
having a substantially constant radius. In other embodiments, the
tobacco spacing device may comprise at least one disc rotatable
about an axis parallel to the bead and movable into and out of the
bead while rotating, the disc having a thickness that increases
from the edge to the centre of the disc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] For a better understanding of the invention and to show how
the same may be carried into effect reference is now made by way of
example to the accompanying drawings in which:
[0018] FIG. 1 shows a longitudinal cross-section through a length
of continuous wrapped tobacco bead according to a first embodiment
of the invention;
[0019] FIG. 2 shows a longitudinal cross-section through a length
of continuous wrapped tobacco bead according to a second
embodiment;
[0020] FIG. 3 shows a longitudinal cross-section through a length
of continuous wrapped tobacco bead according to a third
embodiment;
[0021] FIG. 4 shows a plan view of a conventional ecreteur trimming
device;
[0022] FIG. 5 shows a plan view of an ecreteur trimming device
according to an embodiment of the invention;
[0023] FIG. 6 shows a side view of a trimmer disc of the ecreteur
of FIG. 5;
[0024] FIG. 7 shows a perspective view of a tobacco spacing device
according to an embodiment of the invention;
[0025] FIG. 8 shows a perspective view of a tobacco spacing device
according to an other embodiment; and
[0026] FIG. 9 shows a perspective view of a tobacco spacing device
according to a further embodiment.
DETAILED DESCRIPTION
[0027] The present invention provides a method for forming tobacco
rods suitable for making smoking articles such as cigarettes in
which the tobacco at the end of the rod in the completed smoking
article is covered by folding an overhanging portion of the
wrapping paper inwardly over the tobacco. To achieve this, it is
necessary to provide a tobacco rod (or smoking article) in which
the cigarette paper wrapped around the tobacco extends beyond the
tobacco by an amount sufficient to cover the tobacco when the paper
is folded. The present invention proposes that this be achieved at
an early stage in the conventional cigarette manufacturing process,
during the formation of the tobacco bead and subsequent wrapping of
the bead in cigarette paper.
[0028] Conventionally, loose tobacco is taken from a hopper and
arranged in a thin continuous or endless bead having a width or
thickness substantially the same as the desired width of tobacco in
the completed smoking article. The bead is fed into a garniture
which engages the paper cigarette wrapper around the bead and
secures the wrapper in place with a continuous line of adhesive
running along the length of the paper and bead. The wrapper is also
endless, being supplied to the garniture from a roll having a width
equal to the circumference of the smoking article plus sufficient
extra paper for forming the overlapped stuck seam. This produces a
continuous tobacco rod comprising tobacco wrapped in cigarette
paper. The continuous rod is then cut into single or double length
individual rods for subsequent assembly with filter units.
[0029] According to the invention, before the tobacco bead is
wrapped in the cigarette paper, a plurality of gaps or spaces are
created in the tobacco bead, the gaps being evenly spaced along the
length of the bead. The bead is then fed into a garniture for
wrapping in endless paper in the conventional manner. Thus, a
continuous tobacco rod in which the tobacco filling is divided into
portions by tobacco-less gaps or voids is created. This continuous
rod is then separated into individual rods by cutting through the
paper at positions corresponding with the underlying gaps.
Individual tobacco rods having paper that overhangs at one or both
ends are thereby created, using a manufacturing method and
apparatus that are entirely conventional, requiring only the
addition of a stage for producing the gaps in the tobacco bead.
[0030] The length of the gaps determines the length of the
overhanging paper. Since the overhanging paper is intended for
folding over to cover the exposed tobacco at the end of the rod,
the length of the gaps should be chosen accordingly. Similarly, the
length of the tobacco portions between the gaps should be chosen
with reference to the desired length of tobacco in the completed
smoking articles.
[0031] The desired arrangement of tobacco and overhanging paper can
be achieved in various ways.
[0032] FIG. 1 shows a longitudinal cross-sectional view of a first
embodiment of a continuous tobacco rod before cutting into
individual rods. As described above, the continuous rod 10
comprises tobacco arranged in portions 12 with gaps or voids 14
between the tobacco portions. The tobacco 12 and gaps 14 are
surrounded by a tubular paper wrapper 16, so that the rod is
cylindrical. In this example, each portion of tobacco 12 has a
length t equal to the desired length of tobacco in the completed
smoking article. Each gap 14 has a length g equal to the desired
overhang of paper extending past the end of the tobacco. By cutting
the continuous rod 10 at one end of every gap 14 (the same end for
each gap), flush with the boundary between the gap 14 and the
tobacco 12, the continuous rod 10 is divided into individual rods
18, each comprising an individual length of tobacco 20 inside a
paper wrapper 22 that extends at one end to form an overhanging
foldable portion 24. The arrows c indicate the position of each
cut. The foldable overhang can be used to close one end of the
tobacco rod, while the other end of the tobacco rod is joined to a
filter unit using a tipping paper, to produce a filter tipped
smoking article.
[0033] FIG. 2 shows a second embodiment of a continuous tobacco rod
10. As before, each tobacco portion 12 has a length t equal to the
desired length of tobacco in the completed smoking article. The
gaps 14, however, have a length g equal to twice the desired length
of paper overhang. The continuous rod is cut at positions c that
are aligned with the longitudinal mid-point of each gap. These
cutting locations produce individual rods 18, each comprising an
individual length of tobacco 20 wrapped in a paper wrapper 22 that
has an overhanging portion 24 at both ends of the rod 18. This
arrangement can be used to close both ends of the tobacco rod 18 to
provide a non-filter tipped smoking article.
[0034] FIG. 3 shows a third embodiment of a continuous tobacco rod
10. In this example, the tobacco portions 12 each have a length t
that is twice the length of the intended amount of tobacco in the
finished smoking article. Similarly, the gaps 14 each have a length
g that is twice the length of the desired paper overhang. As in the
embodiment of FIG. 2, the continuous rod 10 is cut at the midpoint
of each gap, thereby dividing the paper 16 corresponding to the
gaps 12 into two parts. These cuts alone, shown as c1, give
double-length tobacco rods, each comprising a length of tobacco
sufficient for two smoking articles plus a paper overhang at each
end. To produce individual, single-length tobacco rods 18,
additional cuts c2 are made at the midpoint of each tobacco portion
12. This produces tobacco rods 18 each comprising an individual
length of tobacco 20 with a paper wrapper 22 having an overhanging
portion 24 at one end only. Thus, tobacco rods the same as those
produced via the embodiment of FIG. 1 can be made by a method that
requires only half as many voids to be made in the tobacco bead.
The cuts c1 through the gaps 14 may all be made first, followed by
cutting the double-length tobacco rods in half with the cuts c2.
Alternatively, the cuts c1 and c2 may be made alternately in
sequence along the continuous rod 10, to divide off each tobacco
rod individually.
[0035] As described above, to fabricate tobacco rods according to
the invention, conventional apparatus may be used to form a tobacco
bead and pass the bead into a garniture for wrapping in cigarette
paper. The bead travels forward along its length during this
process, and after wrapping continues to travel over or past a
cutting blade or other cutting device that cuts the continuous rod
into the individual rod lengths. Before wrapping, the tobacco is
retained in the bead shape by a suction or vacuum belt.
[0036] Two approaches to formation of the gaps in the bead may be
considered. In one approach, sections of tobacco are removed from
the continuous bead. The removed sections extend through the full
width of the bead, thereby creating a discontinuous bead formed
from portions of tobacco spaced by gaps. An alternative approach
comprises parting the tobacco bead at regular intervals and pushing
the tobacco apart on either side of the partings. A tobacco spacing
device may be employed for the removal or parting of the tobacco;
this may take various forms as discussed further below.
[0037] One technique according to the first approach of removing
tobacco sections from the bead uses an ecreteur, or trimming
device, as a tobacco spacing device which removes the tobacco.
Ecreteurs are commonly used for shaping tobacco beads. When a
tobacco bead is initially formed from tobacco taken from a hopper,
the bead will be ragged and of varying width or thickness. One or
more ecreteurs can be used to trim off excess tobacco to produce a
bead of the desired size. The bead width may be constant, or may
not be constant so as to provide different tobacco densities along
the length of a smoking article.
[0038] FIG. 4 shows a plan view of a conventional ecreteur as used
to trim a tobacco bead. A pair of trimmer discs or blades 30, 32
are arranged to rotate in the same horizontal plane, with their
edges adjacent. The two discs 30, 32 rotate in different
directions, as shown in the Figure, so that in a trimming region,
where the discs 30, 32 are adjacent, the edges of the discs 30, 32
are travelling in the same direction. A bead of tobacco 34, carried
for example on a suction belt, passes over the trimming region so
that the underside of the bead 34 is brought into contact with the
rotating edges of the discs 30, 32. The bead 34 travels along its
length in a straight line along a horizontal path equidistant from
the centres of the two discs 30, 32, and in a direction opposite to
the direction of travel of the edges of the discs 30, 32 in the
trimming region as shown by the arrow in the Figure. As the tobacco
bead 34 meets the rotating edges of the trimming discs 30, 32, any
tobacco hanging below the plane of the discs is trimmed or sheared
off from the bead 34 by the discs 30, 32, so that the bead 34 has a
uniform thickness when it exits the trimming region. A wheel 36 is
positioned under the discs 30, 32 in the trimming region, with its
axis of rotation in the horizontal plane. The wheel 36 is arranged
so that it lies in a vertical plane that is at an angle to the
vertical plane occupied by the tobacco bead 34. Its vertical
position is chosen such that the upper edge of the wheel is very
closely adjacent to the trimmer discs 30, 32. As the tobacco bead
34 travels over the discs 30, 32 and is trimmed, the wheel 26
rotates and carries away the tobacco that is removed from the bead
34. The removed tobacco is returned to the hopper for re-use in the
tobacco bead.
[0039] In the example of FIG. 4, the trimmer discs 30, 32 are flat
around their whole circumferences. This configuration trims the
tobacco bead to a constant uniform thickness. Alternatively, the
trimmer discs 30, 32 may have portions at their circumferences
which are higher or lower than other portions of the circumference.
If the discs are synchronised in rotation speed and angular
position so that the different height portions coincide at the
trimming region, the tobacco bead can be trimmed to have a
non-uniform thickness along its length. The rotation of the discs
will give a repeating pattern of thickness, which can be selected
so that the individual parts of the bead intended for individual
cigarettes each have the same pattern of thickness, for example to
provide a higher density of tobacco at the end of each
cigarette.
[0040] Further details of ecreteurs, including their use in
trimming tobacco beads to non-uniform thicknesses, are given in
United Kingdom patent application GB0624771.2 filed on 12 Dec.
2006, entitled "A smoking article and a method and apparatus for
the manufacture of smoking articles".
[0041] According to embodiments of the present invention, it is
proposed to use an ecreteur to remove tobacco from the tobacco bead
to create the required gaps. Portions of the circumference of the
trimmer discs of the ecreteur are configured to have a height above
the remainder of the circumference sufficient to trim away the full
thickness of the bead.
[0042] FIG. 5 shows a plan view of an ecreteur configured according
to this embodiment. Each trimmer disc 30, 32 has its circumference
region shaped so that portions 40 which are raised above the
surface of the disc alternate with portions 38 which lie in the
plane of the disc. The discs have substantially the same thickness
around their circumferences, so the raised portions 40 are
deformations in the surface of the disc, rather than thickened
parts. Thus, the trimming edge provided by the rim of the disc is
maintained around the full circumference, but at differing
heights.
[0043] In this example shown, the trimmer discs 30, 32 are
configured to create four gaps in the tobacco bead per rotation.
Thus, each disc 30, 32 has four raised portions 40, spaced equally
apart around its rim. The length of each raised portion 40 in the
circumferential direction corresponds to the desired length g of
each gap, as discussed with reference to FIGS. 1, 2 and 3. Between
the raised portions 40 are the flat portions 38, each of which has
a circumferential length t corresponding to the desired length of
the tobacco portions between the gaps, also as discussed with
reference to FIGS. 1, 2 and 3.
[0044] FIG. 6 shows a side view of the trimmer disc 32, as seen
along the arrow vi in FIG. 5. This illustrates the varying height
profile of the circumference of the disc 32 to define the raised
portions 40 and the flat portions 38 which are in the plane of the
disc. The raised portions 40 have a height h above the plane of the
disc which is large enough to reach up through the full thickness
of the bead and completely remove all tobacco from the bead over
the length g. If the bead has been previously trimmed by another
ecreteur to achieve a uniform thickness, the flat portions 38 may
be arranged at a height that passes below or level with the
underside of the tobacco bead, so that no trimming occurs outside
of the raised portions 40. Alternatively, the usual ecreteur
trimming function can be provided by the flat portions 38, so that
the height of these portions relative to the bead is selected to
trim the bead to a uniform thickness between the gaps. Further, the
flat portions may be replaced by portions having a varying height
profile, to produce tobacco with a varying thickness over the
length of each individual smoking article, as mentioned above.
[0045] Alternative arrangements may be used to create the gaps in
the tobacco bead by the complete removal of sections of tobacco
from the bead. For example, a spacing device that removes sections
of tobacco by suction could be employed, or a spacing device that
punches sideways through the bead to push out sections of
tobacco.
[0046] An alternative approach to removing sections of tobacco is
to part the tobacco bead at intervals and push the tobacco aside,
along the length of the bead.
[0047] A tobacco spacing device suitable for this is a rotating
screw thread. The screw thread is mounted with its axis of rotation
parallel to the length of the tobacco bead, and positioned such
that its thread extends radially into the tobacco bead. The pitch
of the screw thread is chosen to match the length of the individual
tobacco portions. The beginning of the thread cuts into the moving
tobacco bead with each rotation of the screw, to divide each
portion from the bead. The bead then continues to travel along its
forward path as the screw rotates, but divided into individual
portions with one portion between each pitch of the thread. The
thread itself therefore fills the gaps between the tobacco
portions. Hence, by configuring the thread to have a thickness (in
the direction along the length of the screw thread and the tobacco
bead) that increases with distance along the screw, the tobacco
portions are gradually pushed further apart as they move through
the screw thread, to create gaps of the required length. Thus, the
final thickness of the thread determines the length of the
gaps.
[0048] A single turn of screw thread may be sufficient to divide
and part the tobacco bead adequately, but a more gradual effect may
be preferred, in which case the screw thread may comprise more than
one turn.
[0049] FIG. 7 shows a simplified perspective view of a first
example of a rotatable screw thread suitable for this purpose. The
screw thread 50 is mounted for rotation about a horizontal axis
parallel to the path of the tobacco bead 52, just to the side of
the tobacco bead 52. The tobacco bead 52 is travelling to the right
as illustrated, and the screw thread 50 is rotated clockwise as
seen from the downstream end (with respect to the direction of
travel of the tobacco bead 52) In this example, the front end of
the screw thread 52 is configured as a point 54, with the radius of
the thread gradually increasing along the first half of the length
of the screw. This is similar to a conventional fastening screw,
where the point is used to drive the screw into a surface. In the
present case, the point and increasing radius is instead used to
gradually introduce the thread into the adjacent tobacco bead 52,
thus parting the tobacco. The radius may increase over the whole
length of the screw, or over a first part of the length only.
[0050] The screw thread 50 is fixed except for its rotation, while
the tobacco bead 52 moves forwards through the screw. The speed of
rotation of the screw thread 50 must be properly matched to the
forward linear speed of the tobacco bead 52. Each rotation of the
screw thread 50 introduces a new parting in the tobacco bead 52,
and the continued rotation carries the individual portions of
tobacco 58 through the screw. The entire length of the thread
passes through each parting to create the required gaps 60 in the
tobacco bead. The thread has a thickness 56 that increases with
distance along the screw thread. This gradually pushes the
individual portions of tobacco further apart, until they are spaced
by the appropriate distance. Thus, the final thickness of the
thread is g, the required length of the gaps 60. The tobacco bead
52, continuous on entering the screw thread, is delivered at the
other end divided into individual portions to tobacco 58 whose
length t is determined by the pitch of the screw thread 50, and
spaced apart by regular gaps 60 whose length g is determined by the
thread thickness.
[0051] FIG. 8 shows an alternative embodiment of a rotatable screw
thread 50. The screw thread 50 is positioned adjacent to the
travelling tobacco bead 52 as in FIG. 7, and is again configured so
that the pitch determines the length of the tobacco portions 59 and
the thickness 56 of the thread increases with distance along the
screw to produce gaps 60 of length g in the bead. However, this
screw thread has a thread of a constant radius (constant thread
depth), and does not begin from a point at the front end. Instead,
the screw thread has a leading edge 62 in the form of a blade
arranged radially across the thread. This edge or blade 62 slices
through the tobacco bead 52 as the screw thread 50 rotates, to part
the tobacco. The thickness of the thread then increases from the
thin edge 62 to force the tobacco apart as it moves along the
screw, thereby creating a gap. Each rotation of the screw thread 50
slices through the bead 52 at a new place, owing to the forward
travel of the tobacco bead. Thus, the continuous bead 52 is divided
into portions of tobacco 58 spaced apart by gaps 60, as
required.
[0052] As shown in FIGS. 7 and 8, the tobacco bead 52 is
unsupported. In reality, the bead will be travelling on a suction
belt or other conveying device which would obstruct the screw
thread 50 if the bead 52 was positioned with respect to the screw
thread as shown in FIG. 7 or 8. Therefore, the screw thread should
be spaced from the tobacco bead such that the tobacco passes
through at the outer edge of the thread, so that it can be
supported on its conveying device.
[0053] Other spacing devices for parting the tobacco bead may also
be employed. For example, one or more discs may be mounted in a row
on an axel, for rotation. The edge of each disc forms a blade edge,
and each disc has a thickness that increases from the edge towards
the centre of the disc, to a thickness at least as great as the
desired length of the gaps to be made in the tobacco bead. The
spacing of the discs along the axel corresponds to the desired
length of the individual tobacco portions after formation of the
gaps. The axel is arranged parallel to the tobacco bead. As the
discs rotate, the assembly of discs and axel is moved gradually
closer to the bead so that the disc edges cut into the bead at
spaced apart intervals, to part the tobacco. Further movement of
the assembly pushes the discs further through the bead, and the
increasing thickness of the disc forces the tobacco further apart,
until the desired gap length is achieved. The discs are then
withdrawn.
[0054] FIG. 9 shows a cross-sectional view through a disc assembly,
in the process of creating gaps in a tobacco bead 52. The assembly
comprises an axel 70 arranged parallel to the tobacco bead 52, the
axel carrying five rotatable discs 72. As indicated by the arrows,
the assembly is configured for rotation of the discs 72 about the
axel 70, and for translation of the discs 72 and the axel 70
towards and away from the tobacco bead 52. The discs 72 cut into
the continuous bead 52 to divide it into individual portions of the
tobacco of length t determined by the spacing of the discs. The
thickness of the discs g determines the length of the gaps in the
bead 52 left when the assembly is withdrawn.
[0055] The tobacco bead needs to be kept stationary during this
process for gap formation, however. Alternatively, the disc
assembly can be moved sideways at the same speed as the tobacco
bead, but it will then need to be returned to its start position
for formation of the next set of gaps. Either arrangement is slow
compared to the screw thread example described above, which does
not interfere with the normal forward travel of the tobacco bead.
However, an advantage of the disc assembly is that a single
assembly can be used to create gaps of different sizes, by
alteration of the distance by which the discs are pushed into the
tobacco bead.
[0056] The term "tobacco" as used herein should be understood to
include tobacco per se, and also tobacco materials and derivatives
and other smokable material, alone or in combination. Examples
include, but are not limited to stem, lamina and tobacco dust.
"Tobacco" therefore refers to the smokable material to be included
in a cigarette or smoking article.
[0057] Similarly, the terms "smoking article" and "cigarette" are
to be understood as including cigarettes, cigarillos, slim
cigarettes, cigars and any other smoking article that comprises a
length of smokable material with a paper or similar wrapper, with
or without a filter unit.
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