Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
TOBACCO CAKE SUBDIVIDING APPARATUS FOR USE IN CUT TOBACCO
EXPANDING SYSTEM
Technical Field
This invention relates to a subdividing apparatus used
in a cut tobacco expanding system to subdivide a tobacco
cake which is a consolidated mass of cut tobacco
impregnated with liquid carbon dioxide, into small pieces,
before the impregnated cut tobacco is subjected to flash
drying.
Background Art
As one of filling materials for a cigarette, expanded
cut tobacco is used. The expanded cut tobacco improves the
filling efficiency of the fillers for cigarettes. The
expanded cut tobacco is made by an expanding system, and
the expanding system includes an impregnation container.
Cut tobacco is fed into the impregnation container, and
impregnated with liquid carbon dioxide within the
impregnation container. Then, the impregnated cut tobacco
is taken out of the impregnation container and fed to a
flash dryer. The flash dryer rapidly dries the impregnated
cut tobacco, and by this drying, solid carbon dioxide
contained in the impregnated cut tobacco is vaporized, so
that carbon dioxide gas is emitted from the impregnated cut
tobacco. The emission of the carbon dioxide gas increases
the volume of the cut tobacco. Thus, the impregnated cut
tobacco is expanded.
When the impregnated cut tobacco is taken out of the
impregnation container, the impregnated cut tobacco is
mostly in the form of a large consolidated mass called a
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tobacco cake. Such tobacco cake cannot directly be
subjected to drying by the flash dryer.
Hence, a breaking apparatus for breaking a tobacco
cake is provided in the expanding system, and such breaking
apparatus is disclosed in U.S. Patent No. 4,307,735, for
example. The breaking apparatus of this U.S. Patent
comprises a plurality of rotary shafts arranged parallel
within a horizontal plane, and a large number of blades
attached to the rotary shafts. A tobacco cake is fed from
above the breaking apparatus toward the blades, and broken
by rotation of the blades.
The breaking device of this U.S. Patent, however,
breaks the tobacco cake into fine pieces, so that the
impregnated cut tobacco is badly smashed. Even if this
impregnated cut tobacco broken into fine pieces is then
subjected to drying and thereby made into expanded cut
tobacco, the resultant expanded cut tobacco is small in
particle size and therefore not suitable to be used as a
cigarette filling material.
In order to break a tobacco cake, use of a common
rotary-rake-type subdividing apparatus is thinkable. The
rotary-rake-type subdividing apparatus can, however, not
perfectly subdivide a tobacco cake into tobacco lumps equal
to or smaller than a desired size, so that lots of masses
larger in size than the tobacco lumps, namely large masses
called tobacco loaves and medium masses called tobacco
chunks are left. If the tobacco loaves and tobacco chunks
are directly fed to the flash dryer, the impregnated cut
tobacco in the form of the tobacco loaves and tobacco
chunks cannot be uniformly dried, which leads to lowering
of the quality of the resultant expanded cut tobacco.
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Disclosure of the Invention
The primary object of this invention is to provide a
tobacco cake subdividing apparatus capable of subdividing a
tobacco cake of impregnated cut tobacco obtained from an
impregnation container in an expanding system, in a good
manner, and reducing the breakage of the impregnated cut
tobacco.
In order to achieve this object, a tobacco cake
subdividing apparatus according to this invention comprises
a primary de-clumper arranged to receive a tobacco cake
from an impregnation container, subdivide the received
tobacco cake into tobacco loaves and deliver the tobacco
loaves; and a secondary de-clumper arranged to receive the
tobacco loaves from the primary de-clumper and subdivide
the received tobacco loaves, wherein the secondary de-
clumper includes paired rotary rakes horizontally separated
from each other, for subdividing the tobacco loaves into
tobacco chunks and delivering the tobacco chunks downward,
and a movable rake wall located below the paired rotary
rakes, the movable rake wall being moved from one side
where one of the rotary rakes is located to the other side
where the other of the rotary rakes is located while the
movable rake wall vertically overlaps the rotary rakes so
that the movable rake wall cooperates with the rotary rakes
to subdivide the tobacco chunks into tobacco lumps.
In the above-described subdividing apparatus, the
tobacco cake is first roughly subdivided into tobacco
loaves by the primary de-clumper, and then the resultant
tobacco loaves are further subdivided by the secondary de-
clumper in two stages. Specifically, the primary and
secondary de-clumper subdivide the tobacco loaves into
tobacco chunks by the paired rotary rakes, and then further
subdivide the tobacco chunks into tobacco lumps by
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cooperation between the paired rotary rakes and the movable
rake wall. Since the tobacco cake is subdivided into the
tobacco lumps in a plurality of stages, the subdividing
power required in each stage is small, so that the breakage
of the impregnated cut tobacco is reduced to a great degree.
The movable rake wall overlaps the paired rotary rakes
in the manner such that the movable rake wall engages with
the rotary rakes. Thus, the movable rake and the paired
rotary rakes cooperate to subdivide the tobacco chunks. In
this case, desirably, the secondary de-clumper further
comprises a lap adjustment device for adjusting overlap
between the rotary rakes and the movable rake wall. The
secondary de-clumper can further comprise a speed
adjustment device for adjusting a rotational speed of the
rotary rakes and a moving speed of the movable rake wall.
By adjusting the overlap, the lap adjustment device
reduces the breakage of the impregnated cut tobacco and
adjusts the size of the tobacco lumps obtained by
subdividing the tobacco chunks.
The speed adjustment device reduces the breakage of
the impregnated cut tobacco and adjusts the subdividing
performance of the secondary de-clumper.
Specifically, each of the rotary rakes can include a
rotatable roller and a plurality of rake rows provided on
the cylindrical surface of the roller. In this case, the
rake rows are disposed in a circumferential direction of
the roller with spaces between, and each of the rake rows
has a large number of rake pins arranged along the axial
direction of the roller with spaces between.
Desirably, between the paired rotary rakes, there is a
positional relation such that the rake pins are at equal
positions or in phase with respect to the axial direction
of the roller, while the rake rows are at different
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rotational phase with respect to the circumferential
direction of the roller. Thus, at any rotational angle of
the rotary rakes, the rake pins in at least one rake row
cover the space between the rollers and prevent the tobacco
loaves from just passing through between the rollers.
In one aspect, the movable rake wall is located below
the paired rotary rakes and middle between the paired
rotary rakes, and includes a rotary shaft extending
parallel to the rotary rakes, and a large number of rake
discs mounted on the rotary shaft. The rake discs are
disposed in the axial direction of the rotary shaft with
spaces between, in the manner such that each rake disc is
located between the rake pins of each rotary rake. In this
case, the rake discs overlap the rake pins of the rotary
rakes.
In another aspect, the movable rake wall is located
below the paired rotary rakes, and includes a conveyer
extending across the rotary rakes, and a plurality of rake
rows provided on the conveyer. The rake rows are disposed
in a width direction of the conveyer, and each of the rake
rows has a large number of rake pins disposed in the
direction of traveling of the conveyer with spaces between.
As the conveyer travels, each rake row passes between the
rake pins of each rotary rake. In this case, the rake pins
on the conveyer overlap the rake pins of the rotary rakes.
Brief Description of the Drawings
[FIG. 1] A diagram schematically showing a cut tobacco
expanding system.
[FIG. 2] A plan view showing a secondary de-clumper in
an embodiment.
[FIG. 3] A perspective view showing part of the
secondary de-clumper in FIG. 2.
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[FIG. 4] A diagram showing a power transmission system
for the secondary de-clumper in FIG. 2.
[FIG. 5] A diagram schematically showing an adjustment
device for adjusting the level, or height of a drum rake in
FIG. 2.
[FIG. 6] A graph showing relation between the
rotational speed of the secondary de-clumper and the
proportion of tobacco lumps remaining.
[FIG. 7] A graph showing relation between the
rotational speed of the secondary de-clumper and the
average particle size of impregnated cut tobacco.
[FIG. 8] A graph showing relation between the distance
between rotary rakes and a drum rake and the average
particle size of impregnated cut tobacco.
[FIG. 9] A diagram schematically showing a secondary
de-clumper in a modified example.
Best Mode of Carrying out the Invention
A tobacco expanding system in FIG. 1 includes an
impregnation container 2. The impregnation container 2
receives cut tobacco and impregnates the received cut
tobacco with liquid carbon dioxide. Then, the impregnated
cut tobacco is taken out of the impregnation container 2,
passed through a subdividing apparatus 4, and then fed to a
flash dryer.
In this embodiment, the subdividing apparatus 4
includes a primary de-dumper 6, a storage container 8 and
a secondary de-clumper 10. More specifically, as clear
from FIG. 1, the primary de-clumper 6 includes a grid 12.
The grid 12 extends horizontally and has a plurality of
parallel bars 12a. Immediately above the grid 12, a
plurality of rotary rakes 14 are disposed in the
longitudinal direction of the grid 12 with specified spaces
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between. Each rotary rake 14 has a rotatable roller 14a
and two rows of rake pins 14b projecting from the
cylindrical surface of the roller 14a. The two rows of
rake pins 14b are separated in a diametrical direction of
the roller 14b, and the individual rake pins 14b have an
end bent along the direction of rotation of the roller 14a.
The impregnated cut tobacco taken out of the
impregnation container 2 in the form of a tobacco cake is
fed to the primary de-clumper 6 from above the primary de-
clumper 6. The primary de-clumper 6 subdivides the tobacco
cake into a large number of tobacco loaves by cooperation
between the rotary rakes 14 and the grid 12, and feeds the
resultant tobacco loaves to the storage container 8. The
size of the tobacco loaves is determined primarily by the
pitch between the rake pins 14b and the distance between
the parallel bars 12a of the grid 12.
The storage container 8 temporarily stores the tobacco
loaves, and then the tobacco loaves are fed from the
storage container 8 to the secondary de-clumper 10.
When the tobacco cake passes through the primary de-
clumper 6, the primary de-clumper 6 causes some impregnated
cut tobacco particles to separate from the tobacco cake and
tobacco loaves. As a matter of course, those separated
impregnated cut tobacco particles are also fed to the
storage container 8 with the tobacco loaves.
Next, referring to FIGS. 2 to 5, the secondary de-
clumper 10 will be described.
As shown in FIG. 2, the secondary de-clumper 10 has a
housing 16. The housing 16 has an open top and bottom,
respectively. Within the housing 16, a pair of rotary
rakes 18 is disposed. The rotary rakes 18 are horizontally
separated from each other.
Like the above-described rotary rakes 14, each rotary
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rake 18 includes a roller 20. The roller 20 includes a
roller shaft, and is rotatably fitted to the housing 16 at
the opposite ends of the roller shaft. The roller 20 has
four rake rows 22 on the cylindrical surface thereof, and
the rake rows are disposed in the circumferential direction
of the roller 20 at regular intervals. Each rake row 22
has a large number of rake pins 24 projecting from the
cylindrical surface of the roller 20. The rake pines 24
are disposed along the axial direction of the roller 20
with the same pitch P and in phase. That is, the rake pins
24 in the four rake rows are at equal positions in the
axial direction of the roller 20.
As clear from FIG. 2, the rake pins 24 of the paired
rotary rakes 18 are in phase in the axial direction of the
roller 20. Hence, the paired rotary rakes 18 have four
rake pins 24 each, in one vertical plane.
As clear from FIG. 3, the paired rotary rakes 18 are
rotated about their respective axes with a phase difference
of 45°. Thus, when the paired rotary rakes 18 are rotated
in the opposite directions at the same speed, the rake rows
22 of one of the paired rotary rakes 18 and the rake rows
22 of the other pass through between the rollers 20 of the
rotary rakes 18, alternately. Thus, when the paired rotary
rakes 18 are viewed from above, the space between the
rollers 20, 20 is always covered with any of the rake rows
22 of the paired rotary rakes 18.
Specifically, each rake pin 24 has a length somewhat
shorter than half the distance between the rollers 20 and a
diameter of about 9 mm. The pitch P between the rake pins
24 is determined depending on the size of an inlet of the
flash dryer, and desirably, smaller than the pitch between
the above-mentioned rake pins 14b. In the present
embodiment, the pitch P between the rake pins 24 is equal
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to or less than 100 mm.
Below the paired rotary rakes 18, a drum rake 26
forming a movable rake wall is disposed. The drum rake 26
includes a rotary shaft 28, and the rotary shaft 28 is
located between the rollers 20. The rotary shaft 28
extends parallel to the rollers 20 and is rotatably fitted
to the housing 16 at the opposite ends thereof.
On the rotary shaft 28, a large number of rake discs
30 are mounted. The rake discs 30 are disposed along the
axial direction of the rotary shaft 28 at regular intervals,
in the manner such that each rake disc 30 is located
between the rake pines 24. Hence, the pitch between the
rake discs 30 is equal to the pitch P between the rake pins
24, and the distance between the rake disc 30 and the
adjacent rake pin 24 in the axial direction of the rotary
shaft 28 is P/2.
In the present embodiment, the rotary shaft 28 has a
diameter almost equal to the diameter of the roller 20, and
the rake disc has an outside diameter almost equal to the
outside diameter of the rotary rake 18.
The paired rotary rakes 18 and the drum rake 26 are
rotated by a common electric motor 32. FIG 4 shows a power
transmission path from the electric motor 32 to the rakes
18 and 26.
The roller shaft of each roller 20 has an end
projecting from the housing 16, and as shown in FIG. 4,
sprockets 34, 36 are mounted on the respective projecting
ends of the roller shafts. Also the rotary shaft 28 has an
end projecting from the housing 16, and a sprocket 38 is
mounted on this end.
The sprocket 36 arranged on the electric-motor 32
side in FIG. 4 has a double structure comprising two
sprocket members 36a, 36b. The sprocket member 36a and an
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output sprocket 40 of the electric motor 40 are connected
by an endless drive chain 42.
Further, a tension sprocket 44 is rotatably fitted to
the housing 16. The tension sprocket 44 is located on the
electric-motor 32 side. An endless linking chain 46 is
arranged to pass around the tension sprocket 44, the
sprocket member 36b, the sprocket 34 and the sprocket 38.
Hence, when the electric motor 32 is driven, drive power is
first transmitted by the drive chain 42 to one of the
rollers 20, or in other words, the electric-motor-32-side
rotary rake 18, so that this rotary rake 18 is rotated
counterclockwise in FIG. 4 as indicated by an arrow.
The traveling of the drive chain 42 rotates the
sprocket member 36b, which causes the linking chain 46 to
travel. Consequently, also the other rotary rake 18 and
the drum rake 30 are rotated, in a manner linked with the
electric-motor-side rotary rake 18. Here, the other rotary
rake 18 and the drum rake 30 are rotated clockwise in FIG.
4 as indicated by arrows. It is to be noted that in FIG. 4,
each rotary rake 18 is represented as the orbit described
by the end of the rake pin 24 in rotation.
As shown in FIG. 2, the electric motor 32 is
electrically connected to an inverter-type speed adjustment
device 48. The speed adjustment device 48 can adjust the
rotational speed of the electric motor 32, and therefore,
the rotational speed of the paired rotary rakes 18 and the
drum rake 26.
Further, the drum rake 26 is fitted to the housing 16
using a level adjustment device. The level adjustment
device can adjust the level, or height of the drum rake 26
relative to the paired rotary rakes 18, or in other words,
the vertical distance D between the drum rake 26 and the
paired rotary rakes 18.
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More specifically, as shown in FIG. 5, the level
adjustment device 49 includes a pair of slots 50 formed in
the housing 16. The slots 50 extend vertically. The
rotary shaft 28 of the drum rake 26 has opposite ends
extending through both slots 50, respectively. Support
plates 52 are fitted to the rotary shaft 28 at the opposite
ends thereof, using a bearing. Each support plate 52 is
fixed to the housing 16 by four fitting bolts 54 and nuts
(not shown) disposed at the four corners of the support
plate.
For the fitting bolts 54, a large number of through-
holes 56 are formed in the housing 16. The through-holes
56 are arranged vertically with specified spaces between,
on both sides of the slot 50. Hence, the level, or height
of the drum rake 26, namely the distance D can be adjusted
by selecting the through-holes 56 into which the fitting
bolts 54 should be inserted.
By adjusting the distance D, the overlap of the rake
disc 30 relative to the rake pin 24 can be varied within
the range of the length of the rake pin 24. In the present
embodiment, the distance D is adjusted within the range of
85 mm (corresponding to the maximum overlap) to 155 mm
(corresponding to the minimum overlap).
It is to be noted that also the tension sprocket 44
is fitted to the housing 16 in a vertically movable manner,
and that the level, or height of the tension sprocket 44
can be adjusted in a similar manner to the drum rake 26.
Hence, even when the distance D is adjusted, the tension
sprocket 44 can impart a desired tension to the linking
chain 46.
When tobacco loaves are fed from the storage
container 8 to the secondary de-clumper 10, the tobacco
loaves are subdivided into tobacco chunks smaller in size
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than the tobacco loaves by rotation of the paired rotary
rakes 18, or in other words, the rake pins 24 of the paired
rotary rakes 18, and the resultant tobacco chunks are fed
onto the drum rake 26.
The diameter of the rake pins 24 is about 9 mm, which
is enough to withstand the load required for subdividing
the tobacco loaves, but small. Hence, when the tobacco
loaves are subdivided by the rake pins 24, the breakage of
the impregnated cut tobacco is reduced.
Then, when the tobacco chunks pass through the drum
rake 26, the rake discs 30 cooperate with the rotary rakes
18 to subdivide the tobacco chunks that have passed through
between the rotary rakes 18, further into tobacco lumps of
a desired size smaller than the size of the tobacco chunks.
Consequently, from the secondary de-clumper 10, the
tobacco lumps are delivered with some impregnated cut
tobacco particles. The impregnated cut tobacco particles
include not only those separated when the tobacco cake was
subdivided but also those separated when the tobacco loaves
and tobacco chucks were subdivided.
The tobacco lumps and impregnated cut tobacco
particles delivered from the secondary de-clumper 10 are
then fed to the above-mentioned flash dryer, and rapidly
dried and thereby expanded within the flash dryer.
FIG. 6 shows the result of experiment, where examples
El to E4 of the secondary de-clumper 10, which were
different in the distance PJ2 between the rake pin 24 and
the rake disc 30 and the distance D, were used changing the
rotational speed of the rotary rakes 18 and the drum rake
26, and the proportion of the tobacco lumps remaining in
the impregnated cut tobacco delivered from the secondary
de-clumper 2 and the average particle size of the
impregnated cut tobacco delivered from the secondary de-
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clumper 2 were measured.
The distance P/2 and the distance D in examples E1 to
E4 are as shown in table 1 below.
Table 1
Pl2 (mm) D (mm)
Example E1 25 85
Example E2 25 135
Example E3 40 85
Example E4 40 135
The proportion of the remaining tobacco lumps is
expressed as a percentage relative to the amount of the
tobacco loaves fed from the primary de-clumper 6, which is
considered as 100. As clear from FIG. 6, in examples El to
E4, the proportion of the remaining tobacco lumps was
reduced to about 400 or lower.
As clear from FIG. 7, considering that the initial
average particle size of cut tobacco before impregnation
was 2.41 mm, in the impregnated cut tobacco obtained by
examples El to E4 of the secondary de-clumper 10, the
average particle size was only reduced to 80 to 93 0 of the
initial average particle size.
A broken line in FIG. 7 represents the average
particle size (1.66 mm) of impregnated cut tobacco obtained
by a comparative example of the secondary de-clumper. The
comparative example of the secondary de-clumper includes a
rotor and a spiral row of rake pins provided on the
cylindrical surface of the rotor. In addition, according
to the comparative example of the secondary de-clumper, the
proportion of the remaining tobacco lumps was about 800 or
higher, and the average particle size of the impregnated
cut tobacco was reduced to about 70 0 of the initial
average particle size.
Thus, in the subdividing apparatuses 4 having
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examples E1 to E4 as a second de-clumper 10, the tobacco
cake is subdivided into small pieces in a good manner,
which allows the impregnated cut tobacco to be thereafter
dried uniformly. Further, since the breakage of the
impregnated cut tobacco is reduced, high-quality expanded
cut tobacco can be produced.
As clear from FIGS. 6 and 7, in any of examples E1 to
E4 of the secondary de-clumper 10, as the rotational speed
of the secondary de-clumper 10 increases, the amount of the
remaining tobacco lumps decreases and the average particle
size of the impregnated cut tobacco decreases.
Thus, from the result of measurement in FIG. 7, the
relation between the rotational speed of the secondary de-
clumper and the average particle size of the impregnated
cut tobacco as shown in FIG. 8 is drawn. FIG. 8 shows that
under a fixed rotational speed of the secondary de-clumper,
as the distance D between the rotary rakes 18 and the drum
rake 26 increases, the rate of reduction of the average
particle size of the impregnated cut tobacco decreases.
Hence, by adjusting the distance D, or in other words, the
overlap between the rake disc 30 and the rake pin 24, the
average particle size of the impregnated cut tobacco can be
controlled to be within a desired range.
More specifically, the breakage of the impregnated
cut tobacco is thought to be reduced for the following
reason: As the distance D increases, the overlap decreases,
so that the proportion of the tobacco chunks passing
through the drum rake 26 without being broken by the rotary
rakes 18 and the drum rake 26 increases.
Thus, the degree to which the tobacco chunks are
subdivided, or in other words, the average particle size of
the impregnated cut tobacco can be easily maintained at a
desired level, in a manner depending on the distance D,
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namely the distance between the rotary rakes 18 and the
drum rake 26.
The present invention is not limited to the above-
described embodiment but can be modified in various ways.
The rotary rakes 18 and the drum rake 26 of the
secondary de-clumper 10 can be rotated by separate electric
motors, independently.
Further, as shown in FIG. 9, the secondary de-clumper
can use a conveyer-type movable rake wall in place of the
drum rake 26. In this case, the movable rake wall includes
a conveyer 58 located below the paired rotary rakes 18, and
a plurality of rake rows 60 provided on the conveyer 58.
The rake rows 60 are disposed in the width direction of the
conveyer 58 with spaces between, and each rake row has a
large number of rake pins 62 arranged in the direction of
traveling of the conveyor 58 with spaces between.
As the conveyer 58 travels, each rake row 60 passes
between the rake pins 24 of each rotary rake 18. Like the
above-described drum rake 26, the level, or height and the
traveling speed of the conveyer 58 can be adjusted.
In the case of this conveyer-type movable rake wall,
as the conveyer 58 travels, each rake row 60 passes between
the rake pins 24 of each rotary rake 18, where the rake
rows 60 and the rake pin rows 22 cooperate to subdivide the
tobacco chunks.
