Note: Descriptions are shown in the official language in which they were submitted.
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Apparatus and method for forming tobacco portions
.
Description:
The invention relates to an apparatus for form-
ing portions of fibrous material, particularly cut
tobacco, by separating a preferably underweight rough
portion from a strand of the fibrous material and the
addition of an equalising portion de-termined by the
weighing of the rough portion, wherein a plurality of
balances, in particular two, are adapted to be fed al-
ternately with individual rough portions and the com-
plete portions can be carried away. The invention also
relates to a method which is applied in conjunction with
the apparatus according to the invention for the form-
ation of the tobacco portions.
For the packing of portions of cut tobacco the
most accurate possible metering is necessary. Because
of legal regulations, underweight portions are basically
impermissible. Overweight metering should also be
avoided as far as possible.
In one kno~n apparatus for metering cut
tobacco (German Application A 2,338,374) a continuous
strand of pressed tobacco conveyed in the downward
direction is first formed from the more or less dis-
ordered stock of cut tobacco. From this strand the indi-
vidual rough portions are separated by a suitable ~r$
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separating device, and fed alternately to one or the other
balance- The balances determine the difference be-
tween the respective rough portion and the ~desired3por-
tion. Fine tobacco is fed by a separate fine metering
device in accordance with the shortage, until the
desired portion is obtained. The latter is then
passed through a hopper to a discharge conveyor.
In this known apparatus the rough and adjusted
portions are guided and passed on in the region of the
balances by means of pivotable flaps, which guide the
portion in one direction or the other in accordance with
the relative position. The portions then slide through
the action of gravity downwards on the respective flaps.
Because of the time required for the pivoting movements,
the use of these flaps has been found disadvantageous in
practice.
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Taking as starting point the prior art
described, the object of the invention is to provide an apparatus
for portioning and metering in particular cut tobacco,
in which extremely accurate portions of desired amount
can be formed and transported in a very efficient manner.
In order to achieve this object, the apparatus
according to the invention is characterised in that the
rough portions separa-ted from the strand are each re-
ceived in a compartment of a rotatable intermediate con-
veyor and through the partial rotation of the latter
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can be fed to one or the other balance.
By means of this intermediate conveyor, which
is in the form of a star feeder having compartments
open towards the outside in the radial direction,
efficient transfer of the separated rough portions to
one or the other balance is possible, while the tobacco
portions are handled gently. The star feeder only makes
rotations along part of a circle in each case for
the purpose of conveying a rough portion and at the same
time moving a free compartment into the position for
receiving the next rough portion. The star feeder is
preferably formed with three compartments, each of which
occupies a circumferential region of about 120, so
that a rotation of the star feeder through 120 is
sufficient to bring a compartment open at the top into
the position for receiving a rough portion and to bring
the other two compartments into discharge positions
directed obliquely downwards or towards the side. The
balances, or their receiving members, are corresponding-
ly laterally offset and disposed beneath the intermedi-
ate conveyor, so that the portions are advanced solely
through the rotary movement of the star feeder.
According to a further proposal of the in-
vention, further respective star feeders are disposed
below and laterally offset relative to the intermediate
conveyor in the form of a star feeder, each of them
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serving as balance receiver members to receive the rough
portion fed by the intermediate conveyor and determining
the actual weight of the portion. Each of t~lese star
feeders serving as a baLance receiver member is connected
directly to a precision balance by means of a balance
arm, which in turn is connected to a balance beam of the
precision balance. After the rough portion has been
received in the balance receiver member, the weight is
accordingly determined immediately. In addition,
a difference portion is added directly to the rough
portion, u~til the tobacco portion reaches the desired
weight (desired portion). The latter is then passed
on to a discharge conveyor by the balance receiver member
in the form of a conveyor (star feeder).
The star feeders constitu-ting the balance
receiver members are of the same construction as the
star feeder used as intermediate conveyor, or of similar
construction. The relative positions of the three
star feeders in relation to one another are determined
by the geometrical rela-tionships, in such a manner that
in each case an upwardly directed compartment is used
to receive a tobacco portion and the downwardly directed
compartments are used to carry away a tobacco portion.
Each precision balance is connected to a fine
metering device, which preferably corresponds to the
fine metering device of German Application A 2,338,374.
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This (known) fine metering device is equipped with a
number of barbed rollers which feed an accurately
metered difference portion to the rough portion in the
region of the balance receiver member.
The mode of operation and the control of this
fine metering device are so designed that any defects
in the formation of the rough portion are also appropri-
ately taken into account. In order to obtain con-
tinuous maximum performance, the fine metering device
is so adjusted that the difference portion must be fed
to the rough portion within a predetermined short work-
ing cycle. If the rough portion has a weight below
the predetermined margin, the difference portion cannot
be fed during the working cycle. In this case the
feeding of the difference portion by the fine metering
device is continued until the desired portion is
-3 obtained. The respective balance receiver member is
not advanced on the completion of a working cycle, but
will be advanced only at the switching cycle next
occurring for the balance receiver member in question.
If on the other hand the rough portion fed
to the precision balance has a weight clearly below the
desired weight, or above the desired weight, this rough
portion is treated as a defective portion and is sep-
arately discharged by corresponding operation of the
balance receiver member.
Other features of the invention relate to the
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structural conformation of the star feeders and of a
substantially vertically disposed conveyor well for the
tobacco before the formation of the rough portion.
One exemplary embodiment of the apparatus
according to the invention will be explained more fully
below with the aid of the drawings, in which:
Figure 1 shows the apparatus in side view and
vertical section,
Figure 2 shows part of the apparatus similarly
to Figure 1, but to a larger scale,
Figure 3 shows a still further enlarged part
of the apparatus, with details essential to ~he invention,
in a similar view to Figures 1 and 2, and
Figure 4 is a horizontal section through a
vertical conveyor well in the apparatus.
The apparatus shown as a whole in Figure 1
3 corresponds in basic construction and in respect of its
essential cycle of functioning to the apparatus accord-
ing to German Application A 2,338,374. The main
parts of this apparatus are an upright conveyor well
10, a portion distributor device 11, (two) fine metering
devices 12 and 13, and a discharge conveyor 14 for
correctly metered tobacco portions (desired portions 15).
After being appropriately prepared by suitable
conveyor means (German Application A 2,338,374), the
cut tobacco is fed to the conveyor well 10. Inside the
latter a tobacco strand compressed in the direction of
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conveyance, that is to say downwardly, is formed. For
this purpose the conveyor well 10 is formed with a cross-
section decreasingin the direction of conveyance. This
decrease in cross-section is in turn i-tself achieved by
means of conveyor belts 17 and 18 which lie opposite
one another and whose conveyor faces 19 and 20 respect-
ively are guided to converge in the downward direction. The con-
veyor faces l9 and 20 bound the conveyor well 10 on sides opposite one
another. The other-two sides, offset thereto, of the conveyor well
10 are formed by fixed upright well walls 21 and 22. The
conveyor faces 19 and 20 extend between the welL walls 21
and 22, so that a conveyor well 10 of closed cross-sec-tion
and decreasing in width in the direction of conveyance
is formed. The conveyor faces 19 and 20 are held in
position by fixed, downwardly converging supporting walls
23 and 24, in such a manner that a certain compacting
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pressure is exerted by the conveyor faces 19 and 20 on
the tobacco strand 16.
The conveyor belts 17, 18 are guided over
mutually offset guide rollers 25, 26 at the bottom out-
let end of the conveyor well 10, so that the tobacco
strand 16 can pass freely out of the conveyor well 10.
At the bottom the conveyor well 10 is followed
by a fixed separating well 27. Inside the latter a
roughportion 28 of tobacco is separated from the
advancing tobacco strand 16. This separation is here
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effected with the aid of comb-like separator tools 29
and 30 , through the movement of the latter relative to
one another, preferably in accordance with the arrange-
ment according to German Application A 2,338,374.
The rough portion 28 is of such a size that as a rule it
is slightly below the weight of the desired portion 15.
If this weight is 50 g, the rough portion 28 is for
example metered in the range between 47 and 45 g.
The aforesaid rough portion 28 is received by
an in-termediate conveyor 31 and by the latter is trans-
ferred all;ernately to one of two balance receiver
members 32 and 33 for checking the weight conveyed.
After the rough portion 28 has been made up to the
desired weight, the desired portion 15 thus formed is
passed from the balance receiver member 32 or 33 to the
discharge conveyor 14.
The intermediate conveyor 31 is in the form
of a star feeder comprising three compartments 34, 35
and 36 spaced about 120 apart. These compartments
are open on the side lying outwards in the radial
direction. The compartments 34, 35, 36 are filled
in each case in an upwardly directed position (compart-
ment 34) and are emptied, through the dead weight of the
tobacco portion (rough portion 28), in the two altern-
ative positions inclined downwards or directed towards
the side. The compartments 34, 35, 36 are
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divided off from one another by radially directed par-
titions 37, 38, 39, which are spaced apart at angles of
120. These partitions meet at the centre or axis of
rotation of the star feeder, while at their radially
outer ends the partitions 37, 38, 39 form thickened
portions ~0 of substantially triangular cross-
section. These portions 40 form funnel-shaped
guide surfaces 41 for the compartments 34, 35, 36, in
such a manner that the tobacco portions are given a
de-termined direction of movement, mainly when leaving a
compartment 34, 35, 36. The radially inner base of
the compartments 34, 35, 36 is formed with a rounding
42.
The partitions 37, 38, 39 arranged in star
form and constructed in the manner described above
are disposed between side discs 50, which in the present
case are circular. These discs form at the same time
the side boundaries o~ the compartments 34, 35, 36.
In addition, the side discs serve to mount the shafts
and drives for the rotary movement of the star feeders.
The star feeder constructed in this form and
serving as intermediate conveyor 31 is rotatable
by 120 at a time in one direction or the other.
In the stationary position one compartment (compartment
34 in Figure 3) is always directed upwards to receive
a rough portion 28, while the other compartments 35
and 36 point obliquely downwards and sideways. These
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last-mentioned compartments are emptied in this
position.
The balance receiver members 32 and 33 are
in the present e~em~lary embodiment likewise in the
form of star feeders, and have the same constructional
features as the intermediate conveyor 31. The two
balance receiver members 32, 33 in the form of star
feeders are laterally offset and disposed beneath the
intermediate conveyor 31, in such a manner that a rough
portion 28 slipping out of the downwardly pointing com-
partments 35 and 36 passes into a top compartment 34
of one of the balance receiver rnembers 32,33. In these
star feeders also the tobacco portions, namely desired
portions 15 or any defective portions, are emptied out
of one of the downwardly or laterally directed compart-
ments 35,36. The balance receiver members 32,33 in
the form of star feeders are disposed in the direct
proximity of the intermediate conveyor 31, which is
likewise in the form of a star feeder.
The balance receiver members 32 and 33 are
each coupled to a respective precision balance 43, 44
for the determination of the actual weight. For this
purpose the star feeders constituting the balance
receiver members 32,33 are rotatably connected in the
region of their axes of rotation 45 to a respective
carrier arrn 46,47, which in turn is connected to a
balance beam 48,49 of the associated precisiorl balance
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43,44. The rough portion 28 introduced into an
upwardly pointing compartment 34 of the balance receiver
member 32,33 is thereby directly weighed.
Through the relative positions of the balance
receiver members 32,33, a difference portion can be
introduced in the respective upwardly pointing compart-
ment 34 simultaneously with and independently of the
rough portion 28 until the desired portion 15 has been
accurately achieved. For this purpose the respective
fine metering devices 12 and 13 are disposed above and
laterally offset relative to the balance receiver
members 32,33, each of these devices having a transfer
passage 51,52 leading into the region above the upwardly
directed compartment 34 of the balance receiver member
32,33. The difference portion determined in accord-
ance with the weight of the rough portion 28 is accord-
ingly likewise delivered into the respective upwardly
directed compartment 34. Because of the shape and
dimensions of the compartments 34, 35, 36 there are no
spatial bottlenecks.
The fine metering devices 12, 13 in the
present exemplary embodiment are constructed substan-
tially like the apparatus according to German
Application A 2,338,374. Fine tobacco 53 is accord-
ingly fed by means of a belt 54 directed obliquely down-
wards and taken over by a first barbed roller 55. The
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latter cooperates with a second barbed roller 56 for
the purpose of forming as uniform as possible a layer
57 of tobacco on the first barbed roller 55. A
barbed wheel 58 which then follows lifts the layer 57
of tobacco off the barbed roller 56 and delivers it onto
a chute 59 directed obliquely downwards, that is to say
towards the balance receiver member 32,33. The chute
59 is in turn provided with a downwardly pointing
bent-over arm 60 serving as additional guide means.
The beginning and the end of the fine metering process
are determined by a closure flap 61, which lies against
the arm 60 when the fine metering process is inter-
rupted (shown in solid lines).
The size of the difference portion fed to the
balance receiver member 32, 33 is governed on the one
hand by the duration of the opening of the closure flep
61 and on the other hand by the controllable duration
of the operation of the barbed rollers 55, 56~58.
In detail, the procedure comprises adjusting
the balance receiver members 32, 33 to a determined
switching cycle. Simultaneously with the feeding of
the rough portion 28 into the compartment 34 of a balance
receiver member 32, 33, a residual portion 62163, if
one is left over from the preceding metering cycle, is
fed into the same compartment 34. If as a result the
desired weight (desired portion 15) is achieved, the
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fine metering device 12, 13 does not after all come into
action. The respective balance receiver member 32, 33
is on the contrary moved on one step in the cycle.
If, on the other hand, the desired weight is not achieved
with the aid of the residual portion 62,63, the fine
metering device 12,13 is operated, with the closure flap
61 open, through the driving of -the barbed rollers 55,
56, 58, in such a manner that an additional difference
portion is introduced into the respective compartment 34
by way of the chute 59. When the desired weight is
reached, the closure flap 61 is moved into the closed
position and at the same time the barbed rollers 55, 56,
58 are halted. However, a certain residual portion 62,
63 is still formed, and is added in the manner described
to the next rough portion 28.
Below the balance receiver members 32, 33,
which are in the form of star feeders, outlet funnels
63, 64 and 65 are disposed in the present exemplary
embodiment. The central outlet funnel 64 in the
present case is formed at the top with a funnel opening
66 widened towards both sides. This opening is of
such a size and so disposed that the mutually facing
compartments 35 and 36, pointing downwards and towards
the side, of the balance receiver members 32 and 33
empty into the outlet funnel 64. The latter
serves to receive desired portions 15. The discharge
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conveyor 14, constructed as a -trough conveyor, is
advanced (cyclically) in such a manner that after
each weighing and metering cycle a conveyor container
67 is situated under the outlet funnel 64. The bal-
ance receiver members 32 and 33 are accordingly turned
in opposite directions when a correct desired portion 15
has been formed and is to be fed to the discharge con-
veyor 14. The (central) outlet funne] 64 is provided
exclusively for this purpose.
The respective outer outlet funnels 63 and 65
are exclusively associated with the one and the other of
the balance receiver members 32, 33. These outlet
funnels 63 and 65 are so shaped that any defective por-
tions are carried away to the side, and in any case
cannot pass into the discharge conveyor 14. The outlet
funnels 63 and 65 are accordingly intended for overweight
defective portions and for defective portions which are
below the permissible margin.
The metering device constructed in the manner
described above, particularly for tobacco portions, is
above all characterised by extreme precision together
with gentle handling and high eff`iciency. Determining
factors in this regard are the star feeders serving as
intermediate conveyors 31, on the onehand, and the bal-
ance receiver members 32, 33, on the other hand, ensur-
ing great efficiency through the rotary movement.
