WO2016046678A1

WO2016046678A1 - Unit and method for recovering tobacco from rejected products in machines for making smokers' articles

Info

Publication number: WO2016046678A1
Application number: PCT/IB2015/056833
Authority: WO
Inventors: Fausto Mengoli; Massimo Sartoni
Original assignee: G.D S.P.A.
Priority date: 2014-09-26
Filing date: 2015-09-07
Publication date: 2016-03-31
Also published as: EP3197302A1; PL3197302T3; EP3197302B1

Abstract

A unit for recovering tobacco from rejected products in machines for making smokers' articles, in particular cigarettes (S), comprises conveyor means (2) configured to move a sequence of smokers' articles (S) along a feed direction (B) transversal to their axes (A) between a pickup position and a disposal position, at least one tobacco recovery channel (7), at least one reject collector (3) and a cutting unit (12) operatively interposed between the pickup position and the disposal position and configured to separate the main portion (S1 ) from the filter (F) of each smokers' article (S). The unit also comprises pneumatic means (6) associated with the tobacco recovery channel (7), operatively located along the conveyor means (2) and configured to generate a negative pressure or an overpressure at at least one smokers' article (S) along the conveyor means (2) in order to extract the tobacco (T) from the main portion (S1).

Description

DESCRIPTION

UNIT AND METHOD FOR RECOVERING TOBACCO FROM REJECTED PRODUCTS IN MACHINES FOR MAKING SMOKERS' ARTICLES

Technical field

This invention relates to a unit and a method for recovering tobacco from rejected products in machines for making smokers' articles and to a machine for making smoker's articles and comprising the unit.

Hereinafter in this description, reference is made, by way of example only and without losing in generality, to smokers' articles such as cigarettes.

Background art

During the production of cigarettes, the total number of cigarettes made inevitably includes defective cigarettes among the cigarettes which meet accepted standards of quality. In light of this, cigarette making machines are equipped with numerous checking devices by which each cigarette is tested for conformity to specifications. In effect, it is necessary, for example, to check that every cigarette made contains the right quantity of tobacco, that there is enough tobacco at the end opposite the filter to make that end sufficiently compact to prevent the tobacco from falling out, that the paper wrapped around the tobacco is correctly glued and is not torn or stained, and so on.

Cigarettes found to be defective are rejected at specific expulsion stations, thus becoming reject products, and are collected, usually in specific containers, and then transferred to specific machines especially designed to recover the tobacco from them.

In these machines, the defective cigarettes are crushed or the paper is cut lengthways by a blade, and the different cigarette parts (filter, paper and tobacco) are separated. The filters and paper are scrapped, whereas the tobacco is recovered and then re-used in cigarette making machines. There are numerous examples of machines of the above mentioned type for recovering tobacco from defective cigarettes and publications EP2289356A1 , EP0990395A1 and US5000196A, for example, describe three different types.

The machines concerned are usually relatively complex and expensive. Also, their use has major negative aspects in terms of wasted time and energy in that the defective cigarettes must be collected, transferred to the machine which crushes them and separates out the different materials they are made of, and the tobacco recovered must be stored and then taken to the cigarette making machine which re-uses it.

Moreover, crushing the cigarettes or cutting the paper with a blade inevitably deteriorates the quality of the tobacco recovered, which is broken up into very short fibres containing a large amount of dust and which is therefore not very suitable for making good quality cigarettes. Another prior art machine is disclosed in document EP2730182, which describes a tobacco recovery unit in which cutting means first cut off the filter from the body of the cigarette and blowing means then extract the tobacco from the tubular wrap of the cigarette.

Disadvantageously, the solution described in EP2730182 has numerous drawbacks, connected mainly with the high level of tobacco loss and the difficulty of combining the continuous movement of the conveyor with the efficiency of emptying the cigarette.

Disclosure of the invention

This invention therefore has for an aim to provide a unit and a method for recovering tobacco from rejected products in machines for making smokers' articles to overcome the disadvantages described above with reference to the prior art.

More specifically, the aim of this invention is to provide a unit for recovering tobacco from rejected products and capable of maximizing the degree of material recovery.

Another aim of the invention is to provide a unit for recovering tobacco from rejected products and which operates in-process and at high speeds. These aims are achieved by a unit for recovering tobacco from rejected products in machines for making smokers' articles, having the features described in one or more of the appended claims and, more specifically, comprising conveyor means configured to move a sequence of smokers' articles along a direction transversal to their axes of extension between a pickup position and a disposal position, at least one tobacco recovery channel and at least one reject collector for the scrap materials (paper and filters).

According to the invention, the unit comprises a cutting unit operatively interposed between the pickup position and the disposal position and configured to separate the main portion from the filter of each smokers' article and pneumatic means operatively located along the conveyor means and configured to generate a negative pressure or an overpressure at at least one smokers' article along the conveyor means in order to extract the tobacco from the main portion, where the pneumatic means are associated with the tobacco recovery channel.

Advantageously, thanks to the unit of this invention, it is possible to recover the tobacco without subjecting the tobacco to any mechanical or crushing action, while the reject materials (paper and filters) are separated and disposed of in specific, dedicated containers (or collectors). Brief description of the drawings

Further features and advantages of the invention are more apparent from the following exemplary and therefore non-limiting description of a preferred and hence non-exclusive embodiment of a unit and a method for recovering tobacco from rejected products in machines for making smokers' articles, as illustrated in the accompanying drawings, in which:

- Figure 1 shows a side view of a machine for making smokers' articles comprising a unit for recovering tobacco from rejected products according to this invention;

- Figure 2 shows a schematic view of a first embodiment of a unit for recovering tobacco from rejected products according to this invention;

- Figure 2a shows a side view of a detail from Figure 2.

- Figure 3 shows a schematic view of a second embodiment of a unit for recovering tobacco from rejected products according to this invention; - Figure 4 shows a schematic view of a third embodiment of a unit for recovering tobacco from rejected products according to this invention;

- Figure 5 shows a schematic view of a fourth embodiment of a unit for recovering tobacco from rejected products according to this invention;

- Figure 6 shows a side view of a further preferred embodiment of a machine for making smokers' articles comprising a unit for recovering tobacco from rejected products according to this invention;

- Figure 7 shows a schematic view of the tobacco recovery unit of the machine of Figure 6;

- Figure 7a shows a schematic view of a detail from Figure 7 in two different operating conditions.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 1 denotes a unit for recovering tobacco from rejected products in machines for making smokers' articles, in particular cigarettes "S" according to this invention. Hereinafter, reference is made, by way of example only and hence without losing in generality, to smokers' articles such as cigarettes "S", in particular filter-tipped cigarettes.

As this description continues, therefore, reference will be made to "cigarette" or "smokers' article" without distinction and in the most general sense of the term.

Each cigarette "S" (or smokers' article) extends along its main axis "A" of extension and comprises at least a main portion "S1 " and a filter "F" positioned in series along the axis "A".

The main portion "S1 " is basically a paper wrapper containing a predetermined quantity of tobacco.

The recovery unit 1 according to the invention is associated with a machine 100 for making smokers' articles, in particular a filter tip attachment machine, that is to say, a machine configured to combine (in essentially known manner) a filter "F" with the corresponding main portion "S1 " of each cigarette "S".

The machine 100 thus comprises at least one combining station (not illustrated), where each filter "F" is combined with the respective main portion "S1 " and then transported by one or more movement rollers 101 towards an outfeed section 102 of the machine 100.

The roller 101 is preferably provided on its periphery with a plurality of flutes, typically suction flutes, which hold the cigarettes "S" in position.

The one or more rollers 101 are designed to transport the smokers' articles "S" towards an outfeed conveyor 105 located at an end section of the machine 100.

Preferably, along the outfeed path, the machine is also provided with inspection means 103 for checking the quality of each cigarette "S".

For example, the inspection means 103 are configured to check the degree of ventilation of each cigarette "S" or that the end opposite the filter tip contains the right quantity tobacco or that the paper wrapped around the tobacco is correctly glued and is not torn or soiled.

Operatively downstream of the inspection means 103, the machine comprises at least one selector element 104 configured to pick out the defective smokers' articles and to divert them away from the path defined by the one or more rollers 101 .

Preferably, the selector element 104 is configured to distinguish between defective smokers' articles of a first type, which are recoverable, and defective smokers' articles of a second type, which are difficult to recover. Defective smokers' articles of the first type are preferably substantially complete cigarettes with ventilation or insufficient tobacco defects.

Defective smokers' articles of the second type, on the other hand, are smokers' articles at an intermediate processing stage, damaged, for example, by malfunctions or jams, such that their components (paper wrapper, filter, tobacco) are difficult to distinguish.

In light of this, with reference in particular to Figure 6, the selector element 104 comprises detecting and rejecting means 106 configured to reject the defective smokers' articles of the second type and convey them to a release or dumping zone 107. Preferably, the release or dumping zone 107 comprises a conveyor 107a or chute designed to direct such rejects into specific containers without returning them to the production process.

More specifically, the selector element 104 is operatively interposed between the inspection means 103 and the conveyor 105.

Preferably, therefore, the unit 1 for recovering tobacco from rejected products according to this invention is operatively located downstream of the selector element 104.

The unit 1 comprises conveyor means 2 configured to move a sequence of smokers' articles "S" along a direction transversal to their axes "A" of extension between a pickup position and a disposal position. More specifically, the pickup position is preferably located in proximity to the selector element 104 of the machine 100, while the disposal position is located at at least one specific reject collector 3..

It should be noted that in this text, the term "reject" is used to denote those parts of the cigarette "S" (or of the smokers' articles) which are not recovered or returned to the production process, such as, for example, the filters "F" and the paper wrappers "P" of the main portions "S1 ".

Preferably, the conveyor means 2 comprise at least one conveyor belt 4 provided with a plurality of transversal grooves 4a arranged in sequence and each defining a housing for a respective smokers' article or cigarette "S".

In the embodiment illustrated, the conveyor means 2 comprise two facing conveyor belts 4, opposite to each other in such a way as to define a section for the passage of the smokers' articles, delimited both above and below the cigarette "S".

Thus, the conveyor belts 4 move at the same speed and synchronously so that each transversal groove 4a of one belt faces and is superposed on a corresponding transversal groove 4a on the other belt 4.

Preferably, the unit 1 comprises at least one accumulation unit 16 (or hopper 16a) located just downstream of the selector element 104 and configured to define a buffer zone for the cigarettes "S" to be rejected. It is thus advantageously possible to keep the operating speed of the unit 1 independent of that of the machine 100 to allow for peak workloads (when production of rejected products is at its highest).

The conveyor means 2 preferably also comprise at least one retaining device 5 for retaining at least one of the cigarettes "S".

The retaining device 5 is configured to prevent (or limit) the sliding of the cigarette "S" along its axis "A".

In the preferred embodiment, the retaining device 5 is a suction unit (not illustrated in detail) associated with each transversal groove 4a of at least one of the conveyor belts 4. Alternatively, the retaining device 5 might be a pusher which moves towards and away from the filter "F" of the cigarette (see Figure 7a).

Alternatively, the retaining device 5 might be embodied by the conveyor belts 4 themselves, spaced from each other by a gap which is smaller than the maximum transversal dimension (i.e. diameter) of the cigarette "S".

In other words, in this embodiment, the cigarettes "S" are held in position by compression, preferably applied at the filter "F".

Preferably, the unit 1 also comprises pneumatic means 6 operatively located along the conveyor means 2 and configured to generate a negative pressure or an overpressure at at least one smokers' article "S" along the conveyor means 2 in order to extract the tobacco T from the main portion "ST.

Thus, the pneumatic means 6 are located along the conveyor means 2, laterally thereof, in such a way as to face a free end of the cigarette "S". Preferably, the conveyor belts 4 are a little larger in width than a cigarette "S" in order to minimize the distance which the tobacco must travel after it has been blown or sucked out by the pneumatic means, thereby limiting tobacco loss.

More preferably, the width of the conveyor is substantially equal to the length of the cigarette to be broken down/recovered.

In the preferred embodiment, the pneumatic means 6 are located laterally of the conveyor means 2 so that, at least at an operating position thereof, they face the end of the cigarette "S" provided with the filter "F".

Thus, in the preferred embodiment, the pneumatic means 6 comprise a blowing device 6a configured to generate an overpressure inside the cigarette "S" to facilitate removal of the tobacco.

In this embodiment, the unit 1 also comprises a tobacco recovery channel 7 located on the side opposite to the conveyors 2 relative to the pneumatic means 6.

In other words, in the embodiment illustrated, the pneumatic means 6 and the recovery channel 7 are located on opposite sides of the conveyor means, with reference to the feed direction of the conveyors.

Alternatively (or in addition to), in some embodiments not illustrated, the pneumatic means 6 comprise a suction unit juxtaposed with the conveyor means 2 so that, at least at an operating position thereof, they face the free end of the main portion "ST of the cigarette "S".

It should be noted that in this embodiment, the recovery channel 7 is located on the same side of the pneumatic means 6 as the conveyor means 2.

Whatever the case, in both of the embodiments described above, the pneumatic means 6 are associated with the tobacco recovery channel 7. The recovery channel 7 is configured to transport the tobacco recovered by the recovery unit 1 to a feed station (not illustrated) where the tobacco, not processed in any way and therefore suitable for making another cigarette "S" is fed back into the machine 100.

Thus, the recovery channel 7 is preferably in fluid communication with, or otherwise connected to, the hopper (not illustrated) of the machine 100. Advantageously, the tobacco is thus recovered in-process, maximizing recovery efficiency and minimizing operator involvement.

It should be noted that the retaining device 5 described above is particularly useful and effective when used in combination with the pneumatic means 6 because it allows maximizing the blowing and/or sucking action without affecting the position of the cigarette "S".

Thus, the retaining device 5 is operatively located precisely at least at the pneumatic means 6 so as to keep the cigarette "S" in place during the blowing or sucking action of the pneumatic means 6.

Preferably, however, the retaining device 5 operates along the whole of the conveyor belt 4. As regards the pneumatic means 6, these preferably comprise at least one blowing nozzle 8 located laterally of the conveyor 2 and having at least one operating position where it faces the filter "F" of a cigarette "S" in order to generate an overpressure inside the cigarette "S" itself so as to allow tobacco to be extracted from the main portion "S1 ".

It should be noted that in some embodiments (Figure 4) the nozzle might face a mouth of the main portion "S1 " of the smokers' article "S", where the mouth corresponds to the end opposite the free end, which in use is connected to the filter "F".

Thus, in the operating position, the nozzle 8 is substantially coaxial with a flute 4a of the conveyor belt in order to optimize the blowing action.

Preferably, the nozzle 8 is movable at least partly in synchrony with the conveyor means 2 to act on the cigarette "S" along at least one stretch of predetermined length (not on a point) in order to better empty the main portion "ST.

In other words, during the forward motion of the conveyor belt 4, and thus of the flutes 4a, the nozzle 8 is movable in the same direction as the belt 4 from an attached position, where it at least partly faces a respective flute to start blowing, to a detached position by way of an intermediate position of maximum efficiency where the nozzle 8 is fully coaxial with the flute 4a (and thus with the cigarette "S").

To increase the productivity of the unit 1 to make it compatible with the high production capacities of machines which make smokers' articles, the pneumatic means 6 comprise preferably at least one rotatable drum 9 equipped with a plurality of blowing nozzles 8, angularly spaced from each other, each having at least one operating position where it (laterally) faces the conveyor means 2.

Advantageously, the rotational motion of the drum 9 makes the movement of the nozzles 8 less critical in structural terms (reciprocating motion would certainly place more stress on the structure on account of speed). In the preferred embodiments (Figures 2, 3, 4), the pneumatic means 6 comprise a plurality of rotatable drums 9 mounted in sequence along the conveyor means 2 (that is, along the feed direction "B") in order to generate an overpressure at a corresponding plurality of cigarettes "S". Advantageously, the unit can thus operate simultaneously on a plurality of cigarettes "S" either individually or in different runs whereby a cigarette partly emptied by one nozzle is "finished" by the next nozzle.

In light of this, the recovery unit 1 comprises a control unit (not illustrated) configured to synergically combine the movement of the conveyor belt 2 with that of the drums 9 depending on the operating mode preferred by the operator.

More specifically, the unit has at least two operating modes.

In the first operating mode, shown in Figure 2, the conveyor belt 4 moves forward in such a way that each flute 4a faces at least one nozzle 8 of each drum 9.

That way, the nozzle 8 of the first drum 9 (or of the first drums 9) starts the emptying-out action on the main portion "S1", whilst the nozzles 8 after that complete it.

Advantageously, this allows keeping the conveyor means 2 running at high speed without the need for excessively powerful pneumatic means.

Alternatively, in the second operating mode, with reference to Figures 3 and 4, the cigarettes "S" on the conveyor belt can be divided into first

(10a), second (10b) and third smokers' articles (10c) arranged in alternating sequence.

At the same time, the plurality of rotatable drums 9 in turn comprise a first

9a, a second 9b and a third drum 9c which are spaced from each other.

The control unit is configured to drive the conveyor means 2 and the drum

9 in such a way that:

- the first drum 9a, at the predetermined operating position, can be coupled to the first smokers' articles 10a; - the second drum 9b, at the predetermined operating position, can be coupled to the second smokers' articles 10b;

- the third drum 9c, at the predetermined operating position, can be coupled to the third smokers' articles 10c;

Advantageously, thanks to this control logic, using relatively high power pneumatic means 6 maximizes the productivity of the unit 1 .

It should also be noted that the example given can be generalized to a different number of drums 9.

Thus, if there are four drums (a first 9a, a second 9b, a third 9c and a fourth 9d, as shown in Figures 3 and 4) the smokers' articles would be divided into a sequence of fours, with first 10a, second 10b, third 10c and fourth smokers' articles 10d.

Consequently, the control logic described here can be summed up by the equation:

N_t = N_g

where:

N_t is the number of drums;

N_g is the number of groups which the sequence of smokers' articles can be divided into.

It should also be noted that the number of groups corresponds to the distance travelled by the conveyor means 2 between one activation and the next of two nozzles 8 on the same drum 9.

Figure 5, on the other hand, shows a further embodiment of the unit 1 , where there is only one rotatable drum 9 which comprises at least one straight stretch 1 1 a of predetermined length, where each nozzle 8 is movable in parallel with the conveyor means 2 and faces a respective cigarette "S".

In other words, the drum 9 has a plurality of nozzles 8 movable along an annular path having two curved stretches 1 1 b and at least one straight stretch 1 1 a facing (and parallel to) the conveyor belt 2. Advantageously, therefore, the pneumatic means 6, and more specifically, the nozzles 8, can remain active on a single cigarette "S" for a stretch of considerable length, thus maximizing their effect.

Alternatively, if there are less constraints regarding reduced production speed compared to the machines which make the smokers' articles, the conveyor 2 might be moved intermittently in order to maximize the time the nozzles remain active.

It should be noted that, preferably and with reference to Figure 7a, the drum 9 is movable towards and away from the conveyor 2 transversely to the feed direction "B".

Advantageously, that way, the control unit can drive the drum 9, and hence the nozzle 8, towards the cigarette "S", preferably into contact with the filter "F", in order to maximize the blowing effect.

According to a further aspect of the invention, the unit 1 comprises a cutting unit 12 operatively interposed between the pickup position and the disposal position and configured to separate the main portion "S1 " from the filter "F" of each smokers' article "S".

Preferably, the cutting unit 12 comprises at least one blade 13 oriented along the feed direction "B" of the conveyor means 2.

The blade 13 is configured to be positioned between the filter "F" and the main portion "S1 " in such a way as to separate them.

Preferably, the blade 13 has at least one active position in which it protrudes above the conveyor means 2.

More specifically, the conveyor belt 4 has at least one slot 14 or longitudinal slit which divides it into a first part 4b and a second part (or half-part) 4c, both extending along the feed direction "B".

More specifically, the first part 4b is designed to house the main portions

"S1 " of the cigarettes "S" and the second part 4c is designed to house the filters "F" of the cigarettes "S".

The blade 13c is located at the slot 14 or slit and at least partly protrudes above the conveyor belt 4.

Advantageously, that way, the cutting action on the cigarettes "S" is precise and easy.

It should be noted that depending on the embodiment, the cutting unit 12 may be positioned operatively upstream or downstream of the pneumatic means 6.

Preferably, however, the cutting unit 12 is operatively located downstream of the pneumatic means 6.

Advantageously, it is thus possible for the pneumatic means to act directly on the filter "F" to blow the tobacco out of the main portion "S1 " and the cutting unit does not risk damaging the tobacco to be recovered.

Moreover, the presence of the filter "F" guarantees the radial grip of the tobacco wrapper, thus preventing tobacco loss and optimizing tobacco recovery. Operatively downstream of the cutting unit 13, there is, lastly, a rejects 3 - preferably at least two collectors, a first collector 15a designed to collect the filters "F" and a second collector 15b designed to collect the paper wrappers of the main portions "S1 ".

This invention also has for an object a method for recovering tobacco from defective cigarettes "S". Preferably but not exclusively, the method is implemented through use of a tobacco recovery unit 1 according to this invention.

The method comprises a step of feeding a sequence of smokers' articles (in particular, cigarettes "S") along a direction transversal to their axes "A" between a pickup position and a disposal position.

As they are being fed, the smokers' articles are cut in such a way that the main portion "S1 " is separated from the filter "F".

Before or after cutting, the tobacco inside the main portion "S1 " is blown or sucked out in such a way as to empty the paper wrapper.

Preferably, this step comprises blowing through the filter.

The tobacco extracted from the main portion is recovered, whilst the filter and the paper wrapper are disposed of (separately from each other).

The invention achieves the above mentioned aims and brings important advantages.

In effect, the use of a recovery unit capable of extracting the tobacco at high speed without fragmenting it, combined with a cutting unit which can divide the reject materials, makes for an efficient recovery and effective scrap disposal system.

In effect, the presence of a cutting unit which is independent of tobacco extraction allows the cigarette materials to be separated precisely without, however, any unwanted effects (i.e. fragmentation) on the tobacco fibres which can thus be returned to the process immediately without being damaged.

Moreover, the use of a movable nozzle (or a plurality of movable nozzles) allows maximizing productivity by speeding up the recovery process.

Claims

1 . A unit for recovering tobacco (T) from rejected products in machines for making smokers' articles, in particular cigarettes (S), each extending along its main axis (A) of extension and comprising at least a main portion (S1 ) and a filter (F) positioned in series along the axis (A); the tobacco (T) recovery unit comprising:

- conveyor means (2) configured to move a sequence of smokers' articles (S) along a feed direction (B) transversal to the axis (A) between a pickup position and a disposal position;

- at least one tobacco recovery channel (7);

- at least one reject collector (3);

characterized in that it comprises a cutting unit (12) operatively interposed between the pickup position and the disposal position and configured to separate the main portion (S1 ) from the filter (F) of each smokers' article (S) and pneumatic means (6) operatively located along the conveyor means (2) and configured to generate a negative pressure or an overpressure at at least one smokers' article (S) along the conveyor means (2) in order to extract the tobacco (T) from the main portion (S1 ); the pneumatic means (6) being associated with the tobacco recovery channel (7).

2. The tobacco recovery unit according to claim 1 , characterized in that the conveyor means (2) comprise at least one conveyor belt (4) provided with a plurality of transversal grooves (4a) arranged in sequence and each defining a housing for a respective smokers' article (S).

3. The tobacco recovery unit according to claim 1 or 2, characterized in that the conveyor means (2) comprise at least one retaining device (5) for holding down at least one smokers' article (S) and operatively located at least at the pneumatic means (6) in order to hold the smokers' article (S) in place during the suction or blowing action of the pneumatic means (6).

4. The tobacco recovery unit according to any one of the preceding claims, characterized in that the cutting unit (12) comprises at least one blade (13) oriented along the feed direction (B) of the conveyor means (2) and having at least one operating position where it protrudes above the conveyor means (2).

5. The tobacco recovery unit according to claim 4, characterized in that the conveyor means (2) comprise at least one conveyor belt (4) having a slot (14) or slit which divides the conveyor belt (4) into a first part (4b) for housing the main portion (S1 ) of the smokers' articles (S), and a second part (4c) for housing the filter (F) of the smokers' articles (S); the blade (14) being located at the slot (14) or slit and at least partly protruding above the conveyor belt (4).

6. The tobacco recovery unit according to any one of the preceding claims, characterized in that the pneumatic means (6) comprise at least one blow nozzle (8) located laterally of the conveyor means (2) and having at least one operating position where it faces the filter (F) or the mouth of the main portion (S1 ) of a smokers' article (S) to produce an overpressure inside the smokers' article (S) such as to blow the tobacco (T) out of the main portion (S1 ).

7. The tobacco recovery unit according to claim 6, characterized in that the at least one nozzle (8) is movable at least partly in synchrony with the conveyor means (2) to act on the smokers' article (S) along at least one stretch of predetermined length so as to better empty out the main portion (S1 ).

8. The tobacco recovery unit according to claim 6 or 7, characterized in that the pneumatic means (6) comprise at least one rotatable drum (9) equipped with a plurality of nozzles (8) spaced at equal angular intervals and each having a respective operating position where it laterally faces the conveyor means (2).

9. The tobacco recovery unit according to claim 8, characterized in that the pneumatic means (6) comprise a plurality of rotatable drums (9) arranged in sequence along the conveyor means (2) in order to produce the overpressure at a corresponding plurality of smokers' articles (S).

10. The tobacco recovery unit according to claim 9, characterized in that the sequence of smokers' articles (S) comprises first (10a), second (10b) and third smokers' articles (10c) in alternating sequence; the plurality of rotatable drums (9) in turn comprising a first (9a), a second (9b) and a third drum (9c) spaced from each other in such a way that:

- the first drum (9a), at the predetermined operating position, can be coupled to the first smokers' articles (10a);

- the second drum (9b), at the predetermined operating position, can be coupled to the second smokers' articles (10b);

- the third drum (9c), at the predetermined operating position, can be coupled to the third smokers' articles (10c).

1 1 . The tobacco recovery unit according to claim 8, characterized in that the rotatable drum (9) comprises at least one straight stretch (1 1 a) of predetermined length, where each nozzle (8) is movable in parallel with the conveyor means (2) and faces a respective smokers' article (S).

12. A machine for making smokers' articles, in particular cigarettes, each extending along its main axis (A) of extension and comprising at least a main portion (S1 ) and a filter (F) positioned in series along the axis (A); the machine comprising:

- means for making a sequence of smokers' articles (S);

- inspection means (103) for checking the quality of each smokers' article;

- at least one outfeed conveyor (105) configured to move the smokers' articles (S) feeding out of the machine (100);

- at least one selector element (104) configured to pick out the defective smokers' articles (S); characterized in that it comprises a tobacco recovery unit (1 ) according to any one of the preceding claims.

13. The machine according to claim 12, characterized in that the selector element (104) is configured to distinguish between defective smokers' articles of a first type, which are recoverable, and defective smokers' articles of a second type, which are not recoverable.

14. The machine according to claim 13, characterized in that the selector element (104) comprises detecting and rejecting means (105) configured to reject the defective smokers' articles of the second type and convey them to a release or dumping zone (106).

15. The machine according to claim 14, characterized in that the release or dumping zone (106) comprises a conveyor (107) or chute designed to direct the defective smokers' articles of the second type into specific containers without returning them to the production process.

16. The machine according to any one of claims 12 to 15, characterized in that it comprises a hopper for collecting the tobacco (T) and operatively located upstream of the means for making a sequence of smokers' articles (S); the recovery channel (7) being in fluid communication with, or in any case connected to, the hopper in order to allow the tobacco to be recovered in-process.

17. A method for recovering tobacco from rejected products in machines for making smokers' articles, in particular cigarettes (S), each extending along its main axis (A) of extension and comprising at least a main portion (S1 ) and a filter (F) positioned in series along the axis (A); the method comprising the following steps:

- feeding a sequence of smokers' articles (S) along a direction transversal to the axis (A) between a pickup position and a disposal position;

- separating the main portion (S1 ) from the filter (F) of each smokers' article (S); - sucking or blowing the tobacco (T) out of the main portion (S1 ) of each smokers' article (S) in order to empty it;

- recovering the tobacco (T) extracted from the main portion (S1 ) of the smokers' article (S);

- disposing of the filter (F) and of the paper wrapper of the main portion (S1 ).