EP2400863B1

EP2400863B1 - A unit for feeding a flow of tobacco particles in a cigarette maker

Info

Publication number: EP2400863B1
Application number: EP09799411.5A
Authority: EP
Inventors: Fausto Mengoli; Umberto Zanetti
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 2009-02-26
Filing date: 2009-12-17
Publication date: 2014-04-30
Anticipated expiration: 2029-12-17
Also published as: EP2400863A1; CN102333460B; JP5580343B2; JP2012518426A; CN102333460A; ITBO20090110A1; IT1398602B1; WO2010097661A1

Description

Technical Field

The present invention relates to a unit for feeding a flow of tobacco particles in a cigarette maker.

Background Art

A cigarette maker of the prior art is disclosed in EP 1859693 A1 .
Cigarette makers typically comprise a hopper containing a mass of shredded tobacco.
The tobacco is transferred by a carding unit from the hopper to the top inlet end of a descending duct or chute, then taken up at the bottom end of the duct by pneumatic and/or mechanical transfer means, such as will direct a continuous flow of tobacco particles into an ascending duct or chimney delimited by two vertical side walls disposed substantially parallel one with another.
In single track cigarette makers, the top end of the ascending chimney is enclosed by an aspirating conveyor belt fashioned from an air-permeable fabric and running in a direction substantially transverse to the direction of the flow of tobacco rising through the chimney.
The shredded tobacco particles, entrained in a rising air current generated at the base of the ascending chimney, are forced up through the selfsame chimney and attracted ultimately by the aspirating belt, on which they collect gradually to form a continuous layer or stream.
Beyond the ascending chimney, the stream of tobacco is enveloped in a strip of paper material and shaped into a continuous cigarette rod that will be divided up subsequently into single cigarette sticks by rotating cutter means.
In the case of a twin track cigarette maker, the top end of the chimney presents a separator element of ogival section placed so as to split the flow of tobacco particles into two parts, which are formed gradually into respective streams on two aspirating conveyor belts.
In like manner to the single track type of machine mentioned above, the streams are fashioned into respective continuous cigarette rods and divided up by common cutter means into single cigarette sticks.
Accordingly, the flow of tobacco particles is fed through the machine by a unit composed of the descending duct and the ascending chimney, connected one to another by the aforementioned transfer means.
The flow of tobacco particles is not always perfectly uniform on entering the ascending chimney, by reason of the non-homogeneous distribution of tobacco particles having dissimilar physical properties (weight and size).
In single track machines, this can lead to the formation of a stream presenting non-uniform depth and weight, whilst in twin track machines, to which reference is made specifically hereinafter, the depth and weight of the two streams can be different one from the other.
As a result of this drawback, it becomes impossible to produce cigarette rods homogeneously, and by extension, impossible to produce cigarettes matching the close tolerances specified by manufacturers.
It has been found, especially at the high operating speeds of modem cigarette makers (more than twenty thousand cigarettes per minute), that the non-uniform distribution of tobacco particles is attributable to the progressive decrease in velocity of the air rising through the ascending chimney.
In effect, the velocity of the air flow in the bottom part of the chimney is sufficient to entrain and guide the flow of tobacco, whereas in the top part, the velocity decreases due to the fact, in particular, that the cross section of the chimney widens when nearing the aspirating belts.
This drawback, which impacts above all on the smaller tobacco particles, invested with less kinetic energy, cannot be overcome simply by increasing the initial velocity of the air flow, accomplishable for example by increasing the suction force of the aspirating conveyor belts.
In effect, the velocity of the updraught cannot be increased beyond certain limits, otherwise the stream of tobacco would be compacted excessively and damagingly against the belt, and the particles crushed.

Disclosure of the Invention

The object of the present invention is to provide a unit for feeding a continuous flow of tobacco particles, such as will be unaffected by the drawbacks described above.
The stated object is realized according to the present invention in a unit for feeding a continuous flow of tobacco particles, of which the features are recited in one or more of the claims appended.

Brief Description of the Drawings

The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:

figure 1 shows a portion of a cigarette maker comprising the unit according to the invention, illustrated schematically and in section, and with parts cut away in the interests of clarity;
figure 2 shows the machine of figure 1, illustrated schematically in a front elevation;
figure 3 shows an enlarged detail of figure 1;
figure 4 shows an enlarged detail of figure 3;
figure 5 shows a detail of figure 1, illustrated in a second possible embodiment, however not forming part of the claimed invention.
figure 6 shows a detail of figure 1, illustrated in a third possible embodiment, however not forming part of the claimed invention.

Detailed description of the preferred embodiments of the invention

With reference to figures 1 and 2, numeral 1 denotes a machine, in its entirety, consisting in a twin track cigarette maker.
More exactly, the machine 1 comprises a first portion 2 functioning as a feed unit, by which a mass of shredded tobacco held in a storage hopper 3 is drawn off and conveyed as a continuous flow 4 of tobacco particles, and a second portion or unit 5 of conventional embodiment by which the flow 4 of tobacco particles is formed into two continuous streams 6 and 7.
Referring to figure 3, the machine 1 also comprises a garniture unit, schematized as a block denoted 8, by which the two streams 6 and 7 of tobacco are fashioned into two continuous cigarette rods 9.
The continuous rods 9 are divided up by rotating cutter means, schematized as a block denoted 10, into single cigarette sticks 11.
The feed unit 2 conveying the continuous flow 4 of tobacco particles comprises a descending duct or chute 12, of which the top end is connected to the hopper 3 by way of a carding unit 13 equipped with a carding roller 14 rotatable about a horizontal axis 14a normal to the viewing plane of figure 1.
The feed unit 2 further comprises an ascending duct or chimney 15 aligned on a substantially vertical longitudinal axis denoted 15a, of which the bottom inlet end 16 is connected with the outlet end 17 of the descending duct 12 by way of transfer means 18 that consist in a transfer unit 19 conveying the flow 4 of tobacco particles.
The axis of the descending duct, denoted 12a, is inclined from the vertical in such a way as to create an acute angle of predetermined width with the axis 15a of the ascending chimney 15, which is substantially vertical.
The transfer unit 19 consists in a pair of spiked rollers denoted 20 and 21 disposed with axes parallel to the axis 14a of the carding roller 14, revolving substantially tangential one to another and turning anticlockwise as viewed in figure 1.
The one roller 20 functions as a conveyor, by which tobacco dropping from the carding unit 13 is taken up at the outlet end 17 of the descending duct 12, whilst the other roller 21 functions as an impeller by which the tobacco is projected upwards directly into the ascending chimney 15.
The ascending duct 15 is delimited by two side walls 22 and 23, and enclosed at a top outlet end by a pair of mutually parallel aspirating conveyor belts 24 and 25 on which the aforementioned streams 6 and 7 of tobacco are gathered and conveyed.
The two aspirating conveyor belts 24 and 25, which form part of the second unit 5, are set in motion in a direction perpendicular to the viewing plane of figure 1, hence also to the axis 15a of the chimney 15, and fashioned preferably from an air-permeable textile material.
The unit 5 further comprises a separator element 26 of conventional type, interposed between the belts 24 and 25 and directed toward the inside of the ascending chimney 15, presenting an ogival profile and consisting in a bar of which the axis extends parallel to the two belts 24 and 25.
The side walls 22 and 23 rise from the base toward the top convergently, through a distance covering a first lower portion 27 of the chimney 15, and thereafter divergently through a distance covering a second upper portion 28, in such a way as to create a restriction 29 coinciding with an intermediate portion.
The machine 1 further comprises pneumatic means 30 located at the inlet 16 of the chimney 15, by which a flow of air is directed upward and toward the belts 24 and 25.
Also forming part of the machine are pneumatic blending means 31 associated with the lower portion of the chimney 15, consisting in ducts 32 connected to a source 33 of compressed air and communicating with the inside of the chimney 15 by way of openings 34 in the walls 22 and 23, in such a way as to invest the flow 4 of tobacco particles in a direction substantially transverse to the axis 15a of the chimney.
The machine also comprises pneumatic accelerator means 35 connected to a part of the chimney coinciding with or immediately beyond the restriction 29 (relative to the feed direction of the flow 4), consisting in ducts 36 connected also to the source of compressed air 33 and communicating with the inside of the chimney 15 via a plurality of holes 37 with inclined axes passing through the side walls 22 and 23.
Thus, the flow of air generated by the pneumatic accelerator means 35 will present a component oriented toward the aspirating belts 24 and 25, in such a way as to combine with the restriction 29 in counteracting the deceleration of the flow 4 of tobacco particles caused by the gradual widening in section of the chimney 15.
In practice, this enables the flow 4 of tobacco particles rising through the chimney 15 to retain its homogeneous composition, that is to say presenting a uniform distribution of particles having different physical properties, through to the formation of the two streams 6 and 7 on the aspirating belts 24 and 25.
Numeral 38 denotes openings located in both side walls 22 and 23 of the chimney 15, near to the top end, connecting with ducts 39 through which the air entraining the flow 4 of tobacco particles is ultimately released.
The unit 40 for feeding a flow 4 of tobacco particles illustrated in figure 5, not forming part of the claimed invention, differs from the unit 2 described previously inasmuch as the descending duct 12 is substantially vertical and the transfer means 18 consist in a transfer unit 41, similar to the unit 19 described previously, positioned at the outlet end 17 of the duct 12, plus a looped belt conveyor 42 presenting a top branch 43 suspended between two pulleys 44 and connecting the transfer unit 41 with the inlet end 16 of the ascending chimney 15.
The transfer unit 41 comprises two spiked rollers operating in combination one with another, by which the tobacco is transferred from the duct 12 to the top branch 43 of the belt conveyor 42, whereupon the flow 4 of tobacco particles is transported by the selfsame conveyor toward the inlet end 16 of the ascending chimney 15.
Finally, the unit 47 for feeding a flow 4 of tobacco particles as illustrated in figure 6, not forming part of the claimed invention, differs from the unit 2 of figure 1 in that the descending duct 12 is connected to the inlet end 16 of the ascending chimney 15 by way of an arcuate wall 48 functioning as a guide for the flow 4 of tobacco particles.
In this embodiment, the transfer means 18 are provided by the arcuate guide wall 48, operating in conjunction with pneumatic means 49 that consist in a source of compressed air 50 producing a current directed through openings 51 located in the arcuate wall 48, by which the flow of tobacco particles is conveyed along the selfsame wall.
It will be appreciated that a twin track cigarette maker, rather than being equipped with a single ascending chimney 15 presenting a separator element 26 at the top end, might be equipped with two ascending chimneys substantially parallel one with another and feeding tobacco to respective aspirating conveyor belts individually.
In this instance the arcuate wall 48 will be divided into two branches, each feeding the flow 4 of tobacco particles to a respective chimney.

Claims

A unit for feeding a flow of tobacco particles in a cigarette maker, comprising, at least, an ascending chimney (15) enclosed uppermost by at least one aspirating conveyor belt (25) on which the flow (4) of tobacco particles is formed into a stream (6), a descending duct (12) along which tobacco particles are amassed and conveyed, and transfer means (18) interposed between the descending, duct (12) and the ascending chimney (15), the ascending chimney (15) being delimited laterally by two side walls (22, 23) creating a restriction (29) at an intermediate position, the selfsame chimney being divided by the restriction (29) into a lower portion (27) and an upper portion (28), characterized in that the feed unit (2) comprises pneumatic blending means (31) associated with the lower portion (27) of the ascending chimney (15) and acting on the flow (4) of tobacco particles; said transfer means (18) comprise a transfer unit (19) equipped with rollers, by which the descending duct (12) is connected directly to the ascending chimney (15); said transfer unit (19) comprising a conveyor roller (20) by which tobacco is taken up from the descending duct (12), and an impeller roller (21) operating in conjunction with the conveyor roller (20), by which the flow (4) of tobacco particles is projected directly along the ascending chimney (15).
A feed unit as in claim 1, characterised in that said pneumatic blending means (31) are associated with the lower portion of the chimney (15) and consists in ducts (32) connected to a source (33) of compressed air and communicating with the inside of the chimney (15) by way of openings (34) in the side walls (22, 23) in such a way as to invest the flow (4) of tobacco particles in a direction substantially transverse to the axis (15a) of the chimney.
A feed unit as in claim 1 or 2, comprising pneumatic accelerator means (35) associated with the upper portion (28) of the ascending chimney (15), positioned near to or coinciding with the restriction (29) and acting on the flow of tobacco particles.
A feed unit as in claim 2 and 3, characterised in that said pneumatic accelerator means (35) are connected to a part of the chimney (15) coinciding with or immediately beyond the restriction (29); said pneumatic accelerator means (35) consisting in ducts (36) connected to the source of compressed air (33) and communicating with the inside of the chimney (15) via a plurality of holes (37) with inclined axes passing through the side walls (22, 23); the flow of air generated by said pneumatic accelerator means (35) presenting a component oriented toward said aspirating belt (25), in such a way as to combine with the restriction (29) in counteracting the deceleration of the flow (4) of tobacco particles caused by the gradual widening in section of the chimney (15).
A feed unit as in any one of the preceding claims, wherein the cigarette maker (1) is a single track machine.
A feed unit as in any one of the preceding claims, wherein the cigarette maker (1) is a twin track machine.