Note: Descriptions are shown in the official language in which they were submitted.
.56~
The present invention relates to a method and apparatus
for treating tobacco, and more particularly to a method and
apparatus for converting particles or fragments oE tobacco into
a continuous tobacco stream, for example, into a stream which is
ready for trimming and conversion into a wrapped cigarette rod.
Still more particularly, the invention relates to improvements
in a method and apparatus for building a tobacco stream from a
plurality of different types of tobacco, particularly from
tobacco shreds and so-called short tobacco. The term "short
tobacco" is intended to embrace tobacco dust as well as
fragments which are removed from an unequalized tobacco stream
by a cutting action during conversion of such stream into a
trimmed stream or filler which is ready for wrapping into
cigarette paper, imitation cork or other suitable wrapping
material.
It is already known to build a tobacco stream from
freshly supplied tobacco shreds which are withdrawn from a
Eirst magazine and are mixed with short tobacco, i.e., with
tobacco which is removed from an unequalized stream by trimming
and is returned to the distributor of the stream forming machine,
e.g., oE a cigare-tte maker. It is also known to place the
magazine or accumulated short tobacco upstream of the magazine
for freshly supplied tobacco shreds and to employ a suitable
conveyor which is provided with spaced-apart entraining elements
in the form of vanes or blades capable of removing batches of
short tobacco from the upstream magazine and thereupon tobacco
shreds from the downstream magazine. Reference may be had to
commonly owned U S. Patent No. 4,185,644 granted January 29, 1980
to Heitmann et al. The conveyor of Heitmann et al. is an endless
elevator having an elongated upwardly moving stretch whose vanes
- 2 - ~
move first past the upstream magazine for short tobacco and
thereupon past the downstream magazine for fresh tobacco shreds.
A paddle wheel equalizes the accumulated tobacco batches, each
of which contains short tobacco as well as tobacco shreds, before
the batches are dumped into an upright duct for conversion into
a continuous stream which contains a surplus of tobacco. The
stream is then trimmed by removing the surplus therefrom whereby
the removed surplus constitutes or forms part of short tobacco.
A suitable conveyor system, e.g., a pneumatic conveyor or a
combination of pneumatic and mechanical conveyors, is utilized
to transport short tobacco from the trimming station to the
magazine which is adjacent to the upwardly moving reach of the
aforementioned endless elevator. As a rule, the magazine which
serves for storage of freshly supplied tobacco shreds also
contains some particles of stem ribs, birds' eyes and like
relatively hard and often bulky ragments of tobacco which should
be segregated from other particles prior to the trimming and
wrapping steps. To this end, the duct which receives batches of
tobacco Erom the vanes of the endless elevator is normally
ollowed by a classifying unit which segregates particles of ribs,
stem and the like from satisfactory particles before the
satisfactory particles are converted into a stream which is
advanced toward and past the trimming device or devices. The
quality of the distributor (i.e., of that part of a cigarette
making or an analogous machine which delivers tobacco particles
to the stream forming or stream building station) greatly affects
the quality of the ultimate product. Thus, a satisfactory
distributor must form a uniform or nearly uniform tobacco stream
with a minimum of short tobacco because the latter is inferior
to freshly supplied tobacco shreds and is reprocessed primarily
-- 3 --
because of the hi~h cost of tobacco, i.e., the manufacturers of
cigarettes strive to use up all or nearly all parts of tobacco
leaves including laminae as well as ribs, stem and relatively
small fragments (short tobacco) which necessarily develop in the
course of processing (especially trimming) in a cigarette making
machine. Furthermore, ~he quality of cigarettes is more
satisfactory if the percentage of short tobacco in each of a
long series of cigarettes is uniform, i.e., if the quantity of
short tobacco does not fluctuate extensively from cigarette to
cigarette or from cigarette pack to cigarette pack.
Commonly owned German Offenlegungsschrift No. 27 29 730
discloses a distributor wherein short to~acco which develops as
a result of trimming a continuous tobacco stream is reprocessed
without delay and without permitting such tobacco to mix with
freshly supplied tobacco shreds. ~oreover, such short tobacco is
prevented from accumulating into a large mass prior to
reintroduction into the stream building zone. It has been found
that such distributors are quite satisfactory in many respects
with th~ important exception that the quantity or percentage of
short tobacco is likely to vary from cigarette to cigarette or
from a relatively short Eirst series to the next-following series
of cigarettes.
One feature of the invention resides in the provision
of a method of forming a tobacco stream which contains
predetermined percentages of plural types of tobacco, especially
freshly supplied tobacco shreds and short tobacco. The method
comprises the steps of establishing and maintaining discrete
first and second sources of first and second tobacco types,
withdrawing from the first source (e.g., from the source which
contains short tobacco) a succession of discrete batches at least
-- 4 --
some of which contain a surplus of tobacco of the first type
(i.e., more than would be required to maintain the preselected
percentage of such tobacco in the stream), removing the surplus
from the respective batches so that~ upon completion of the
removing step, each of the batches at most contains a
predetermined maximum acceptable quantity of tobacco of the
first type, transporting successive batches (namely, those
batches which do not contain more than the predetermined quantity
of tobacco of the first type) past the second source, augmenting
successiv~ batches by adding to each batch tobacco of the second
type during transport oE successive batches past the second
source, and converting the augmented batches into the stream.
The removing step preferably includes segregating the
surplus from successive batches which contain a surplus of
tobacco of the first type by resorting to a combing action.
The augmenting step preferably includes adding a surplus
of tobacco of the second type to at least some of the batches,
and the method then prc~erably further compris~s the step of
equalizing the augmented batches prior to the converting step.
Such equalizing step includes segregating surplus tobacco of the
second type Erom the respective augmented batches so that each
batch which advances beyond the equalizing or segregating station
contains an accurately determined quantity of tobacco of the
first type as well as an accurately determined quantity of
tobacco of the second type. Such batches can be readily converted
into a stream wherein each unit length contains a preselected
percentage of tobacco of the first type as well as a preselected
percentage of tobacco of the second type.
The method preferably further includes the steps of
establishing an elongated path which extends past and beyond the
-- 5 --
z
first and second sources and advancing a plurality of equidistant
pockets (such pockets can be de~ined by an endless conveyor band
or belt and by vanes or blades which are attached to and extend
from the outer side of the endless belt or band) along the path.
The withdrawing step of forming the batches then includes at least
partially filling the pockets during advancement of the pockets
past the first source and the removing step includes expelling
tobacco of the first type from successive pockets in a portion
of the path which is disposed between the first and second sources.
The augmenting step then includes overfilling (all or certain)
successive pockets during advancement of pockets past the second
source, and the equilizing or segregating step may comprise
removing from successive pockets any tobacco of the second type
which extends from overfilled pockets. The path preferably slopes
upwardly in a direction from the first source toward, past and
beyond the second source.
It is further preferred to maintain the quantity of
tobacco in at least one of the sources at a substantially constant
value. This facilitates orderly removal of preselected quantities
~0 of tobacco from the respective source, i.e., the formation of
batches which necessitates a minimum of oqualizing or surplus-
removin~ action.
~ s mentioned above, at least the major part of at least
one source (preferably the first source) consists of tobacco
shorts or short tobacco. As further mentioned above, short
tobacco can be obtained (and is normally obtained) by trimming
the stream. The trimmed-off surplus is delivered to the first
source to form an accumulation of tobacco of the first type.
Each of the withdrawing and augmenting steps may include
combing the mass of tobacco in the respective source to
z
respectively remove batches from the first source and to add
tobacco of the second type to successive batches during transport
of such batches past the second source.
The novel features which are considered as characteristic
of the invention are set forth in particular in the appended claims.
The improved apparatus itself, however, both as to its construction
and its mode of operation, together with additional features and
advantages thereof, will be best understood upon perusal of the
following detailed description of certain specific embodiments
with reference to the accompanying drawing.
FIG. 1 is a somewhat schematic longitudinal vertical
sectional view of an apparatus which embodies the invention; and
FIG. 2 is an enlarged transverse sectional view of that
portion of the apparatus which is located within the broken-line
circle II shown in FIG. 1.
FIG. 1 shows a portion of a cigarette making machine
having a distributor 2 which includes a hopper 1 for a supply ~
of fresh tobacco. The hopper 1 intermittently receives supplies
of fresh tobacco by way oE a gate 3 which opens in response to
signals transmitted by the transducer oE a photocell 6. The
photocell 6 is installed in or on the housing H of the magazine 1
and its transducer generates a signal for opening of the gate 3
when the light beam issuing from the light source of the photocell
6 can reach the photosensitive surface of the transducer, i.e.,
when the photocell 6 is exposed. Such arrangement ensures that
the supply of fresh tobacco in the hopper 1 is at least
substantially constant. The photocell 6 can be said to constitute
a level monitoring device or detector which initiates intermittent
admission of fresh tobacco shreds but is likely to contain some
fragments of ribs, stem, birds' eyes and like undesirable
components which, as a rule, are segregated from the shreds
prior to the formation of a continuous tobacco stream.
The hopper 1 constitutes a main source of supply of
fresh tobacco from a magazine 9 which is mounted in the housing
H at a level below the hopper 1 and receives fresh tobacco from
the hopper 1 in response to rotation of a transfer conveyor 7
having a shaft 7a journalled in the housing H and radially
extending paddles or blades 7b which effect the transfer of
fresh tobacco into the magazine 9. The supply of fresh tobacco
in the magazine 9 is indicated by the reference character 8.
The motor (not shown) which drives the shaft 7a of the transfer
conveyor 7 is set in motion in response to signals generated by
the transducer of a second photocell 11 which is installed in or
on the housing H and monitors the level of the upper surface
of the supply 8. The photocell 11 ensures that the quantity of
fresh tobacco in the magazine 9 is at least substantially constant.
This contributes to the formation of a tobacco stream wherein the
percenta~e of resh tobacco is more likely to be maintained within
a desirable or optimum r~nge.
The distributor 2 Eurther comprises an elevator conveyor
13 lncluding an endless flexible clement in the form Oe a belt
or band 13a and several equidistant entraining elements in the
form oE comb-like vanes or blades 12 extending at an acute angle
to the outer side of the belt 13a and defining therewith a series
of equidistant pockets P. That reach (denoted by the character
13b) of the endless belt 13a which travels upwardly toward, past
and beyond the magazine 9 defines an elongated path a portion of
which is adjacent to the open side of the magazine 9 and a
preceding portion of which is adjacent to a further magazine 37
constituting a source of supply of a second type of tobacco,
Z
namely, short tobacco which is obtained in response to trimming
of the surplus off a continuous tobacco stream formed in the
leftmost portion of the apparatus shown in FIG. 1.
The blades 12 which move upwardly with the ascending
reach 13b of the belt 13a remove small portions or batches of
fresh tobacco from the magazine 9 (i.e., from the supply 8 in the
magazine 9) whenever the elevator 13 is in motion. Such batches
or portions are equalized by a rotating paddle wheel 14 or an
analogous equali%ing device which is preferably of the type
that does not cause any comminution of particles or fragments
which form the supply 8. The equalizing device or paddle wheel
14 ensures that each and every pocket P which advances upwardly
and beyond the magazine 9 does not contain more than a
predetermined maximum quantity of tobacco particles. Its
positioning is preferably such that it removes tobacco particles
which overflow or extend from the neighboring pockets P so that
the extent to which each pocket advancing toward the upper end
turn 13c of the elevator 13 is the same or ne~rly the same.
A pocket P which reaches the end turn 13c drops the
e~ualized quantity of tobacco into an upright duct 16 so that the
latter accumulates a sllpply or pile 17. The height of such pile
is monitored by one or more photoelectric detec-tors 18 which
generate signals serving to control the speed of the motor M
which drives the elevator 13. This ensures that the height of
the pile 17 is at least substantially constant or that such height
fluctuates within a relatively narrow range when the apparatus of
FIG. 1 is in actual use. The lower end portion or outlet 19 of
the duct 16 is located above the path of the carding on a rotary
drum-shaped removing conveyor 21 which is driven to rotate in a
clockwise direction, as viewed in FIG. 1, and to advance a layer
g _
of tobacco particles past an oscillating homogenizing bar 22 of
the type disclosed in commonly owned U.S. Patents Nos. 3,996,943
and 3,996,944 granted December 14, 1976 to Alfred Hinzmann. The
purpose of the homogenizing bar 22 is to ensure that the spaces
between the projections constituting the carding of the removing
conveyor 21 are uniformly filled with particles of tobacco.
Moreover, the bar 22 maintains the lower end portion of the pile
17 in the duct 16 in motion so that the material of the pile 17
is not likely to bridge in the region of transfer of tobacco into
the range of the carding on the removing conveyor 21. The latter
is driven by the motor 101 of a fan 102 in a manner as disclosed
in the aforementioned commonly owned U.S. Patent No. 4,185,644
granted January 29, 1980 to Heitmann et al.
The removing conveyor 21 cooperates with a rapidly
rotating picker roller 23 which expels the particles of tobacco
from the carding and causes such particles to descend onto the
upper reach oE an endless apron conveyor 24 which is driven to
move its upper reach in a direction to the left, as viewed in
FIG. 1. The upper reach o~ the conveyor 24 accumulates a uniform
carpet or sliver of tobacco particles and the leading edge or
leader of such carpet is propelled beyond the leEt-hand end turn
of the conveyor 24 into a classiEying unit 26 wherein the heavier
particles of tobacco are segregated from lighter particles. A
plenum chamber 27a of the classifying unit 26 discharges
streamlets or currents of compressed air downwardly through
a row of orifices 27 so that the currents of air form a curtain
which is traversed by the heavier particles (ribs, stem and birds'
eyes) whose inertia is relatively high. The lighter particles
including shreds and short tobacco are deflected into a hopper 29
and the heavier particles accumulate in a trough 28 to be
-- 10 --
evacuated, either continuously or at regular or irregular
intervals, by a feed screw or the like (not shown). The speed
of the conveyor 24 is selected in such a way that the classifying
unit 26 can effect a highly reliable segregation of heavier
particles from the more satisfactory particles (shreds) as well
as from short tobacco. The opening at the lower end of the hopper
29 receives a portion of a carded drum-shaped conveyor 31 which
transfers the lighter fraction of the material delivered by the
apron conveyor 24 into a tobacco channel 32 below the lower
reach of an elongated belt conveyor 33 which accumulates a
continuous tobacco stream ready to be trimmed and thus converted
into a tobacco filler. The filler is thereupon draped into a web
of cigarette paper or the like to form a continuous cigarette rod.
The rod is severed at regular intervals to yield a succession
or file of discrete plain cigarettes of unit length or multiple
unit length. The means for promoting upward movement of
particles of tobacco in the channel 32 (i.e., toward the underside
of the lower reach oE the conveyor 33) includes a plurality
o~ no~zles 34 which discharge compressed air in an upward direction,
as viewed in FIG. 1. The lowcr reach of the conveyor 33 (which
is Eoraminous) travels below the open underside oE a suction
chamker 33a which attracts the particles of tobacco to the
conveyor 33 so that the latter can build a continuous stream
consisting of tobacco shreds and short tobacco.
The manner in which the structure in the left-hand
portion of FIG. 1 forms a tobacco stream which is then trimmed
and wrapped is disclosed in the aforementioned commonly owned
U.S. Patent No. 4,185,644 to Heitmann et al. This patent also
discloses one mode of gathering short tobacco which is formed
in response to trimming of the stream at the underside of the
~5~2
conveyor 33 and of returning the thus accumulated short tobacco
to the distributor 2 for renewed introduction into the duct 16
and thence into the channel 32.
The magazines 37 and 9 (i.e., the sources of first and
second types of tobacco) are separated from each other by a sheet
metal panel 36 which constitutes the bottom wall of the magazine
9. The conveyor 38 in the lower right-hand portion of FIG. 1
forms part of the means for transporting short tobacco from the
trimming device below the lower reach of the conveyor 33 into
the magazine 37. The trimming device is shown in FIG. 5 of the
aforementioned patent to EIeitmann et al.
In accordance with a feature of the present invention
the housing H of the distributor 2 further contains a surplus
removing device 39 which is installed in the magazine 37 adjacent
to the path of the ascending reach 13b of the belt 13a and serves
to equalize the batches of short tobacco which are withdrawn by
successive pockets P while the pockets advance past the magazine
37 on their way toward the magazine 9. The surplus removing
device 39 performs a combing action .in tha-t it comprises a
plurality of blades or paddles 46 each o~ which resembles a comb
and serves to equalize the batch which is carried by the adjacent
comb-like vane 12 so that the quantity of short tobacco which a
pocket P is allowed to carry toward the magazine 9 is not in
excess of a predetermined value. The illustrated device 39 is a
paddle wheel which rotates its paddles 46 in a counterclockwise
direction, as viewed in FIG. 1, i.e., counter to the direction
of travel of the ascending reach 13b of the belt 13a. The
direction of rotation of the paddle wheel 39 is indicated by
the arrow 41, and the direction of travel of the ascending
reach 13b is indicated by the arrow 42. The polygonal shaft or
- 12 -
~ ~5~
core 44 of the paddle wheel 39 carries four comb-like blades
46 each of which is serrated (see particularly FIG. 2) and
the trapeziform spaces or gaps 47 between the teeth or prongs
46a of the blades 46 are wide and deep enough to allow, with
clearance, for the passage of narrow and slender triangular
prongs or projections 12a of the vanes 12 on the belt 13a. The
end portions of the shaft 44 are rotatable in antifriction bearings
48 and 49 which are installed in the frame members 51 and 52 of
the housing H. The shaft 44 is driven independently of the
elevator conveyor 13 by a discrete prime mover 56 (e.g., a
suitable electric motor) through the medium of a gear transmission
53, 54. The prongs 46a of the blades 46 on the shaft 44 are
preferably trapezoidal, and the depth of the spaces 47 between
the prongs 46a is such that the tips of the triangular projections
12a (which alternate with the trapezoidal prongs 46a) penetrate
approximately midway into the respective spaces 47 when the shaft
44 is rotated and the reach 13b of the belt or band 13a moves
upwardly, as viewed in FIG. 1.
If the operator wishes to change the quantity oE short
tobacco which is entrained by successive vanes 12 of the belt or
band 13a, the positions of the blades 46 with respect to the
shaft 44 are adjusted so that the triangular projections 12a
penetrate deeper or to a lesser extent into the spaces 47. This
can be achieved by shifting the blades 46 radially of the shaft
44. To this end, each blade 46 has two or more elongated slots
57 for screws, bolts or analogous fasteners 58 which extend into
tapped bores of the shaft 44 and can be loosened to allow for
rapid adjustment of the blades.
An important advantage of the improved distributor is
that the batches of short tobacco which are removed by successive
- 13 -
5~
vanes 12 during travel past the magazine 37 are equalized by the
removing device or paddle wheel 39 before the respective pockets
P reach the magazine 9, i.e., before the pockets P are filled
(preferably overfilled) with fresh tobacco of the supply 8.
Since the surplus of fresh tobacco is removed by the equalizing
device 14, the distributor 2 equalizes both types of tobacco so
that each augmented batch whieh reaches the upper end turn 13c
of the elevator 13 and is transferred (by gravity) into the duet
16 contains a predetermined quantity of short tobacco as well as
a predetermined quantity of fresh tobacco.
The surplus removing paddle wheel 39 ensures that the
pockets P cannot be unduly filled with short tobacco, i.e., that
each pocket P is capable of accepting a eertain quantity of fresh
tobaeco (of the second type) so that the augmented batches whieh
are clumped into the duet 16 invariably eontain desired quantities
of a plurality of different tobaeeo types.
The positions oE the blades 46 relative to the shaft 44
of the surplus removing paddle wheel 39 can be readily selected
in such a way that eaeh poeket P aceepts and retains a relatively
small quantity of short tobaeeo. ~oreover, the ~uantity of short
tobacco does not change from pocket to pocket but remains eonstant
as long as the operator desires, i.e., until and unless the
operator decides to change the positions o the blades 46 with
respect to the shaft 44. The selected adjustment of the blades
46 is preferably such that the quantity of tobacco which is stored
in the magazine 37 for short tobacco is at least substantially
constant, i.e., that the paddles 12 remove short tobacco at the
same rate at which such tobacco is formed by the trimming device
below the conveyor 33 and at which the conveyor 38 delivers short
tobacco into the magazine 37.
~ ~.5~i~2
The provision of cooperating projections or prongs 46a
and 12a on the blades 46 and vanes 12 further ensures that the
particles of short tobacco are uniformly distributed as
considered in the longitudinal direction of the pockets P ~i.e.,
at right angles to the plane of FIG. 1). Each prong 12a retains
a certain relatively small quantity of short tobacco, and the thus
obtained batch is then augmented and covered by fresh tobacco which
is withdrawn (by a combing action) from the magazine 9 while the
prongs 12a travel upwardly along the supply 8 of fresh tobacco.
The surplus removing paddle wheel 39 can be replaced
with other types of surplus removing means without departing from
the spirit of the invention. This paddle wheel need not deviate
from conventional paddle wheels which are used in many types of
distributors to remove the surplus of tobacco from the mass which
is withdrawn from a supply of fresh tobacco. However, in contrast
to paddle wheels which are used in conventional distributors, the
paddle wheel 39 equalizes short tobacco beEore such tobacco is
mixed with or augmented by Eresh tobacco (in the magazine 9).
This renders it possible to ensure that each augmented batch
of tobacco which advances beyond the equalizing pa~dle wheel 14
for Eresh tobacco contains a predetermined quantity of short
tobacco as well as a predetermined quantity of fresh tobacco.
At the very least, the quantity of short tobacco in the pockets P
does not exceed a preselected maximum value, and the quantity oE
fresh tobacco also does not exceed a preselected maximum value
because such quantity is limited by the paddle wheel 14.
Another important advantage of the illustrated paddle
wheel 39 for removal of the surplus of short tobacco is that it
enables the tips of the projections 12a to remove fresh tobacco
from the supply 8 by a combing action because such tips are
exposed as a result of rotation of the blades 46 relative to the
oncoming vanes 12 of the belt or band 13a. Furthermore, and as
already explained above, the illustrated paddle wheel 39 renders
it possible to effect uniform or nearly uniform distribution of
short and fresh tobacco along the full length of each poeket P.
This contributes to more satisfactory homogeneousness of tobacco
in the duct 16 and to a more satisfactory classifying action of
the uni-t 26.
In the illus-trated embodiment, the paddle wheel 39 is
loeated at a level below the bottom wall 36 of the magazine 9 so
that the removed surplus of short tobacco returns into the
magazine 37. However, it is equally within the purview of the
invention to aeeumulate short tobacco which is removed from the
poekets P by the blades 46 and to return the thus aeeumulated
short tobacco to the magazine 37 by resorting to a separate
eonveyor, not shown. The illustrated eonstruetion is preferred
beeause it i5 simpler and enhanees the eompaetness oE the
distributor 2.
Experiments with the improved distributor prove that
the equalization of batehes of short tobacco is highly satisfactory
and also that short tobaceo whieh is removecl by the projeetions
46a of the blades 46 is not subjected to a pronounced eomminuting
aetion, i.e., that the paddle wheel 39 does not aet as a trimming
device but rather solely or almost exelusively as a combing means
for removing particles without any comminution. The use of
projections in the form of slender triangles 12a on the vanes 12
eontributes to a reduetion of likelihood of comminution of short
tobaeco which has been withdrawn from the supply in the magazine
37 and travels past the rotating paddle wheel 39.
As a rule, the quantity of fresh tobacco which is
- 16 -
removed Erom the magazine 9 greatly exceeds the quantity of short
tobacco which is withdrawn from the magazine 37. In other words,
the percentage of fresh tobacco in the pile 17 which partially
fills the duct 16 is much greater than the percentage of short
tobacco.
