EP4164418A1

EP4164418A1 - Conveyor for rod-shaped articles and cigarette assembling unit comprising the conveyor

Info

Publication number: EP4164418A1
Application number: EP21731845.0A
Authority: EP
Inventors: Fausto Mengoli; Giuliano Gamberini
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 2020-06-12
Filing date: 2021-06-10
Publication date: 2023-04-19
Also published as: WO2021250605A1; IT202000014077A1

Abstract

A conveyor for rod-shaped articles comprises a conveying surface provided with a succession of seats (4) for holding respective groups of segments (200) and for transversely advancing the groups of segments (200), wherein each suction seat (4) has a middle portion (4a) for receiving a middle segment (210) and a pair of opposite side portions (4b) for receiving respective side segments (220), wherein the conveyor (1) also comprises a pair of side compacting means (6) operating on the side portions (4b) of the seats (4) to progressively compact the side segments (220) towards the middle segment (210) as the conveying surface advances, and a pair of spacing guides (5; 5'; 5'') disposed between the middle portion (4a) and the side portions (4b) of the seats (4) to define a limit stop in the axial positioning of the side segments (220) and to set a predetermined distance between the middle segment (210) and the side segments (220).

Description

DESCRIPTION

CONVEYOR FOR ROD-SHAPED ARTICLES AND CIGARETTE ASSEMBLING UNIT COMPRISING THE CONVEYOR

Technical field

This invention relates to a conveyor for rod-shaped articles and to a cigarette assembling unit comprising the conveyor.

In the context of this invention, the term “rod-shaped articles” is used to denote segments of substantially cylindrical shape, having a main axis of extension (and, more specifically, an axis of symmetry) having different properties and intended to be assembled by specific axial positioning relative to each other to obtain a final product, specifically a cigarette. Preferably, therefore, these rod-shaped articles comprise at least one filter segment and at least one tobacco segment.

Background art

Known in the prior art are cigarettes in which the filter and the tobacco segment have an empty space between them. The empty space is, for example, a ventilation chamber where the outer wrapping paper is provided with ventilation holes. A cigarette of this kind is described, for example, in document GB2260253 in the name of the Applicant.

One of the most common problems encountered when making cigarettes of this kind is being able to position the filter and the tobacco segment correctly relative to each other to ensure that the empty space (ventilation chamber) is of the predetermined size, so that the properties of the cigarette meet a required standard. It is therefore necessary for the production means and the corresponding production process to ensure levels of precision and repeatability sufficient to achieve the required standard of quality. Disclosure of the invention

In this context, the basic technical purpose of this invention is to provide a conveyor for rod-shaped articles and a cigarette assembling unit comprising the conveyor to overcome the above mentioned disadvantages of the prior art.

More specifically, this invention has for an aim to provide a conveyor for rod-shaped articles and a cigarette assembling unit comprising the conveyor which allow achieving high precision and process quality.

The technical purpose indicated and the aim specified are substantially achieved by a conveyor for rod-shaped articles and a cigarette assembling unit comprising the conveyor comprising the technical features described in claims 1 and 12, respectively, and/or in one or more of the appended claims.

According to the invention, the conveyor comprises a conveying surface provided with a succession of seats, preferably suction seats, for holding respective groups of segments and for transversely advancing the groups of articles, wherein each seat has a middle portion for receiving a middle segment and a pair of opposite side portions for receiving respective side segments, wherein the conveyor also comprises a pair of side compacting means operating on the side portions of the seats to progressively compact the side segments towards the middle segment as the conveying surface advances. According to the invention, the conveyor also comprises a pair of spacing guides disposed between the middle portion and the side portions of the seats to define a limit stop in the axial positioning of the side segments and to set a predetermined distance between the middle segment and the side segments.

The groups of segments may, in particular, comprise a pair of tobacco segments and a double filter segment interposed between them. Alternatively, they may comprise a pair of filter segments and a double tobacco segment interposed between them. As a further alternative, the segments may be more than three in number. Furthermore, each of the segments may be any one of: a filter segment, a tobacco segment, a cooling segment or a hollow segment.

It is specified that the term “tobacco segment” is used to denote a segment made of a material capable of releasing an aerosol; for example, the tobacco segment may comprise tobacco leaves, a crimped sheet of tobacco (for example, reconstituted tobacco), paper with a tobacco admixture, cotton, cannabis. More specifically, the tobacco segment may be of traditional type (where the tobacco is burnt) or of HNB type (where the tobacco is heated but not burnt). Preferably, the spacing guides extend along the feed direction, defined by the conveying surface, for a distance corresponding to a plurality of seats. In an embodiment, the conveying surface has a closed-loop shape and the spacing guides extend along the feed direction for a portion of the closed loop. In an embodiment, the conveyor is made in the form of a conveying drum. In this configuration, the spacing guides extend along the feed direction for an angular extent of between 45° and 135°, preferably between 70° and 110°, about the axis of rotation of the drum. In a variant embodiment, the spacing guides extend for the full angular extent of the drum. Each spacing guide has an inside lateral surface and an outside lateral surface directed, respectively, towards the middle portion and the respective side portion of the seats and each spacing guide comprises at least one fixed spacing guide securely anchorable to a fixed portion of a unit for assembling rod-shaped articles. In one particular embodiment, this fixed portion is a portion of the conveyor frame.

In an embodiment, each spacing guide comprises a plate-like element having a main position plane that is disposed perpendicularly to the longitudinal axis of the seats and/or to the axis of rotation of the conveying drum. Preferably, the fixed spacing guides have respective convergent entry portions made on the inside lateral surface so that the middle portion of the suction seats is progressively narrowed during feed, meaning that it converges in width along the feed direction. The outside lateral surfaces of the fixed spacing guides, on the other hand, may be planar for the full longitudinal extent of the spacing guides or for part of the longitudinal extent. In the second situation, the outside lateral surfaces also have respective entry portions which are inclined, in particular convergent, so that each outside lateral surface defines, in cooperation with the respective compacting means, a substantially constant length of the side portions of the seats at the entry portion, thus accompanying the second segments in the axial (adjustment) sliding movement along the seat.

In an embodiment, the outside lateral surface and the inside lateral surfaces are defined, for each spacing guide, by a single fixed spacing guide, preferably defined by the plate-like element. In a possible embodiment, the plate-like element has a constant thickness along its full length or a structure such that the inside lateral surface and the outside lateral surface have the same shape and are offset from each other.

In a different embodiment, each spacing guide also comprises a movable spacing guide disposed externally of and juxtaposed with the respective fixed spacing guide so that an inside surface of each fixed spacing guide and an outside surface of the respective movable spacing guide define the size of the spacing between the middle segment and the respective side segment. Preferably, the movable spacing guides are provided with synchronous motion relative to the conveying surface and are preferably fixed to the conveying surface. According to the invention, the spacing guides are disposed on a longitudinal stretch of the conveying surface which is externally uncovered, that is to say, which has no covering elements. In the embodiment with conveying drum, that means that the spacing guides are disposed on an angular sector of the conveying drum (more specifically, of a peripheral mantle of the conveying drum), where the seats are externally uncovered, hence without corresponding covering elements or surfaces. For this reason, the seats are suctions seats and are preferably provided with holes both in the middle portion and in the side portions.

In an embodiment, the middle portion and the side portions of each seat are defined by a single, uninterrupted seat subdivided by the spacing guides, where the spacing guides have a bottom edge disposed at a minimum distance such as to nevertheless allow end-to-end abutment between the middle and side segments (protruding from the conveying surface when they are inside the suction seats) and the inside and outside lateral surfaces of the spacing guides, respectively In an embodiment, the side compacting means are movable synchronously with the conveying surface and operate on the side portions of the seats with an axial movement to progressively compact the side segments towards the middle segment. Preferably, the compacting means are embodied in the form of rotary disks rotatable about axes which are inclined to the longitudinal axis and/or to the axis of rotation of the conveying drum so that a peripheral portion of the rotary discs moves towards and away progressively from the side portions of the suction seats.

In an embodiment, the conveyor also comprises adjustment means, preferably motor-driven, acting on the spacing guides (preferably the fixed ones) to vary a mutual distance between the spacing guides. Advantageously, the adjustment of the mutual distance between the spacing guides is such as to: adapt the conveyor as a function of a format to be processed, for example, as a function of the length of the middle segment and/or of the side segments and/or of the empty space between them; adapt the conveyor as a function of a dynamic correction signal obtained from an inspection device operating downstream of the conveyor. The invention also relates to a unit for assembling cigarettes of the type having an empty space between filter and tobacco segment, where the unit comprises:

- feed means, specifically a feed drum, for feeding groups of segments, where each group of segments comprises a double segment, specifically a filter segment, and two side segments, specifically tobacco segments, disposed coaxially with the double segment and axially spaced from the double segment; - a conveyor of the kind described in the foregoing, located downstream of the feed means to receive the groups of segments in such a way that the double segments are released in the middle portions of the seats and the side segments are released in the side portions of the seats;

- a rolling unit, located downstream of the conveyor and configured to receive the groups of segments from the conveyor and to join the segments of each group to each other by means of one or more connecting strips according to an axial spacing, defined by the conveyor, between the segments of each group.

In an embodiment, a specific applicator device is provided to release the connecting strips on the groups of segments, which are spaced apart by the spacing guides, at an angular sector of the conveyor.

In a different embodiment, a specific applicator device is provided to release the connecting strips on the groups of segments, which are spaced apart by the spacing guides, at an angular sector of a receiving conveyor located downstream of the aforesaid conveyor.

Preferably, the rolling unit comprises a rolling drum or conveyor and, at or downstream of the rolling drum or conveyor, an inspecting device for checking the spacing between the segments of each group of segments or of each cigarette. The inspection device is preferably an optical inspection device, specifically a camera.

In an embodiment, the inspection device is located adjacent to the rolling drum or conveyor to inspect the groups which are wrapped in the at least one connecting strip, where the groups define a cigarette of double length (hence having two empty spaces at the ends of the double length filter segment).

In a different embodiment, the inspection device is located adjacent to an inspection drum or conveyor located downstream of the rolling drum or conveyor to inspect the single cigarettes obtained by cutting in half the groups which are wrapped in the at least one connecting strip.

In another embodiment, the inspection device is located adjacent to the rolling drum or conveyor to inspect the groups before they are wrapped in the at least one connecting strip. More specifically, the inspection device is located at the rolling drum or conveyor to inspect the groups after one or more connecting strips have been applied on the groups but before the connecting strips are wrapped around the groups The invention also relates to a method for assembling cigarettes, specifically cigarettes having an empty space between filter and tobacco segment and preferably made using a conveyor and/or a unit of the type described in the foregoing, where the method comprises the following steps: - feeding a succession of groups of segments to a conveying surface provided with a succession of transverse seats, where each group of segments comprises one double segment, specifically a filter segment, and two side segments, specifically tobacco segments, disposed coaxially with the double segment and axially spaced from the double segment; - disposing the segments of each group at a predetermined mutual axial distance from each other which is, in particular, adjusted as a function of a current format (parameter) to be processed to define measured spaces between the segments;

- after the step of disposing the segments of each group at a predetermined axial distance, rolling the segments in one or more connecting strips in such a way as to obtain a single article, corresponding in particular to a double-length cigarette, where empty spaces of predetermined size are defined between the segments.

The step of disposing the segments of each group at a predetermined distance is carried out by transversely advancing the middle segment and each side segment on opposite sides of a respective spacing guide and progressively compacting at least the side segment towards the spacing guide in such a way that the spacing guide defines a limit stop for the axial positioning of the side segments and determines the predetermined mutual axial distance. Preferably, this step is also carried out by centring the middle segment in position by means of the inside surfaces of a pair of parallel spacing guides.

It is evident that the invention described above with reference to groups of segments comprising a double-length middle segment and two single length side segments (hence to make double-length cigarettes to be cut in half), is also applicable to groups of segments comprising only two single length segments, specifically one filter segment and one tobacco segment (thus directly making single-length cigarettes). In this configuration, a single spacing guide can be used, instead of two.

Brief description of the drawings Further features and advantages of the invention are more apparent in the indicative, hence non-limiting, description of a preferred but non-exclusive embodiment of a conveyor for rod-shaped articles and a cigarette assembling unit comprising the conveyor, as illustrated in the accompanying drawings, in which: - Figure 1 is a schematic representation of a cigarette assembling unit according to this invention;

- Figure 2 is a schematic view of a part of a conveyor for rod-shaped articles according to the invention, forming part of the unit of Figure 1 ;

- Figure 3 is a cross sectional view of the conveyor of Figure 2 through the section line A-A;

- Figures 4-6 show three different embodiments of a portion of the conveyor of Figure 2;

- Figures 4A-6A show enlarged details from Figures 4-6, respectively; Figure 7 shows a cigarette obtainable using the unit of Figure 1. Detailed description of preferred embodiments of the invention

Figure 1 shows a cigarette assembling unit 1 according to the invention. More specifically, the cigarettes are of the type shown in Figure 7, which illustrates a cigarette 100 having a filter segment 110 and a tobacco segment 120, connected to each other by a connecting strip 130 and axially spaced from each other to define an empty space 140 which is enclosed by the connecting strip 130.

The term “tobacco segment” 120 is used to denote a segment made from a material which is capable of releasing an aerosol. More specifically, the tobacco segment 120 comprises a filling material capable of releasing an aerosol and a wrapper (of tobacco or paper or other suitable material) wrapped around the filling material. The filling material may comprise tobacco leaves, a crimped sheet of tobacco (for example, reconstituted tobacco), paper with a tobacco admixture, cotton, cannabis. More specifically, the tobacco segment 120 may be of traditional type (where the tobacco is burnt) or of FINB type (where the tobacco is heated but not burnt).

Alternatively to the cigarette shown in Figure 7, the smoking article assembled according to the invention might comprise two or more assembled segments and such segments may be any one of: a filter segment, a tobacco segment, a cooling segment or a hollow segment.

The unit 1 comprises a feed drum 2 provided with peripheral suction seats for containing groups of articles, a conveying drum 3, located downstream of the feed drum 2, and a rolling drum 10, located downstream of the conveying drum 3. The number and arrangement of the drums in the unit 1 may vary according to requirements without thereby departing from the scope of the inventive concept of the invention. Further, the drums might be replaced with conveyors of a different kind (for example, conveyor belts) provided they have a conveying surface with transverse seats, preferably suction seats.

The feed drum 2 is configured to transport and feed a succession of groups 200 of articles (Figures 4-6) each made up of one middle segment 210, specifically a double filter segment, and two opposite side segments 220, specifically tobacco segments, aligned with each other and spaced apart by a quantity that is set by specific spacing means upstream (for example, a retractor drum, not illustrated). Alternatively, the middle segment 210 might be a double tobacco segment and the two side segments 220 might be filter segments.

The conveying drum 3 is provided with a succession of peripheral suction seats 4 disposed in parallel with the axis of rotation of the drum 3 and preferably made on a rotary peripheral mantle of the drum 3.

The conveying drum 3 is also equipped with a pair of spacing guides 5 running side by side along a circumferential direction of the conveying drum 3, in particular for an angular extent such that it covers a plurality of suction seats. The spacing guides 5 run parallel with each other along the feed direction defined by the conveying drum 3 and are disposed in such a way as to divide each suction seat 4 into a middle portion 4a and a pair of side portions 4b.

In the embodiment illustrated, each suction seat 4 is defined by a single curved recess extending axially, that is to say, in parallel with the axis of the drum 3, to cover an entire group 200 of segments. In this situation, the aforementioned middle portion 4a and side portions 4b of the suction seats are defined by the positioning of the spacing guides 5. However, in a different embodiment not illustrated, each suction seat 4 might be defined by an axial succession of three (or more) portions divided from each other by ridges or other dividing features.

Further, each portion 4a, 4b of the suction seats 4 is associated with suction holes for holding down a respective segment. More specifically, the spacing guides 5 are disposed in such a way that the middle segment 210 of each group 200 of segments is released into the middle portion 4a of a respective suction seat 4, while the side segments 220 are released into the side portions 4b of the seats.

Each spacing guide 5 is defined by an arcuate plate-like element, preferably having a position plane that is oriented perpendicularly to the axis of the conveying drum 3. Each spacing guide 5 also has an inside lateral surface 5a and an outside lateral surface 5b directed, respectively, towards the middle portion 4a and the respective side portion 4b of the respective suction seat 4.

The conveying drum 3 also comprises a pair of side compacting means 6 operating on the side portions 4b of the suction seats 4 to progressively compact the side segments 220 towards the middle segment 210 as the suction seats 4 advance. In the embodiment illustrated, the side compacting means 6 are embodied in the form of rotary disks rotatable about axes which are inclined to the axis of rotation of the conveying drum 3 and, more specifically, which converge upwardly towards one another so that a peripheral surface of the rotary discs moves towards and away progressively from the side portions 4b of the suction seats 4. In this configuration, the side compacting means 6 are movable synchronously with the suctions seats 4 along a stretch of the angular extent of the conveying drum 3 and operate on the side portions 4b of the suction seats 4 with an axial movement to progressively compact the side segments 220 towards the middle segment 210.

In a variant embodiment not illustrated, the side compacting means 6 may comprise movable pushers, specifically a pair of movable pushers, at each seat 4. The movable pushers are integral with the conveyor and movable by means of a cam.

In a further variant embodiment not illustrated, the side compacting means 6 may comprise blowing elements, specifically a pair of blowing elements, at each seat 4 of the conveyor.

In the embodiment of Figure 4, the spacing guides 5 are fixed and securely anchorable to a fixed frame portion 7. More specifically, the two fixed spacing guides 5 are separate from one another and anchorable individually to the fixed frame portion 7 by respective fixing portions 5c. In a variant embodiment not illustrated, the two fixed spacing guides 5 are applied to a common support which is in turn anchorable to the fixed frame portion 7. More generally speaking, the fixed spacing guides 5 may be anchored to a fixed portion of a unit for making smoking articles or of a machine comprising the conveyor. Further alternatively, the fixed spacing guides 5 may be anchored to a fixed portion of the conveying drum 3.

Also in the embodiment of Figure 4, the fixed spacing guides 5 have respective convergent entry portions 5d made on the inside lateral surface 5a so that the middle portion 4a of the suction seats 4 converges in width along the feed direction, that is to say, it has a progressively decreasing width which has the effect of centring the middle segment 210.

Optionally, again in the embodiment of Figure 4, the outside lateral surfaces 5b are planar for the full longitudinal extent of the fixed spacing guides 5.

The embodiment of Figure 5 differs from the embodiment of Figure 4 in that the outside lateral surfaces 5b of the fixed spacing guides 5 have respective entry portions 5e which are inclined, in particular convergent, so that each outside lateral surface 5b defines, in cooperation with the respective compacting means 6, a substantially constant length of the side portions 4b of the seats 4 at the entry portion 5e. In this configuration, therefore, each side segment 220 is pushed sideways towards the middle segment 210 by the side compacting means 6 and, at the same time, is accompanied, at the opposite end, by the outside lateral surface 5b of the respective fixed spacing guide 5 (defining a curved abutment) against which it comes into permanent abutment.

In the embodiment of Figure 5, too, the fixed spacing guides 5, may have convergent entry portions 5d made on the inside lateral surface 5a.

The embodiment of Figure 6 differs from the embodiment of Figure 4 in that each spacing guide 5 comprises a fixed spacing guide 5’ and a movable spacing guide 5” placed side by side in such a way that the inside surface of the fixed spacing guide 5’ directly faces the middle portion 4a of the suction seat 4 and the outside surface of the movable spacing guide 5” directly faces the side portion 4b of the suction seat 4. In this configuration, the inside surface of each fixed spacing guide 5’ and the outside surface of the respective movable spacing guide 5” define the size of the spacing between the middle segment 210 and the respective side segment 220.

The feed movement of the movable spacing guide 5” is preferably synchronous with the suction seats 4. In an embodiment, the movable spacing guide 5” moves as one with the suction seats 4, for example, by fixing the movable spacing guide 5” directly to the rotary mantle of the conveying drum 3.

In the embodiment of Figure 6, too, the fixed spacing guides 5’, may have convergent entry portions made on the inside lateral surface. In a further embodiment not illustrated, the spacing guides are movable (none of them are fixed). The feed movement of the movable spacing guide is preferably synchronous with the suction seats 4. In an embodiment, the movable spacing guides move as one with the suction seats 4, for example, by fixing them directly to the rotary mantle of the conveying drum 3.

In a variant, these movable spacing guides are in the form of coaxial discs, preferably integral with the conveying drum 3.

In a further variant, these movable spacing guides are protrusions of the seats 4; in other words, these movable spacing guides are an integral part of the conveying drum 3.

More specifically, the movable spacing guides have a twofold function: the first function is that of limit stops for the axial positioning of the side segments 220 (setting a predetermined distance between the middle segment 210 and the side segments 220); the second function is that of compacting (specifically by accompanying) the middle segment 210 and ensuring it is correctly positioned inside the seat 4. In a possible embodiment not illustrated, adjustment means are provided to act on the spacing guides (fixed and/or movable) to vary the mutual distance between them.

Adjusting the mutual distance between the spacing guides allows adapting the conveyor as a function of a format to be processed, for example, as a function of the length of the middle segment and/or of the side segments and/or of the empty space between them. Advantageously, it is extremely quick, easy and economical to perform format changeovers on this conveyor. Adjusting the mutual distance between the spacing guides also allows adapting the conveyor as a function of a dynamic correction signal obtained from an inspection device operating (continuously) downstream of the conveyor.

These adjustment means are preferably motor-driven, for example, using a linear or rotary actuator of the lead nut and screw type or, alternatively, they may be of a hand-operated type, for example, using an adjustment screw. In this embodiment, the fixed spacing guides are preferably mounted on the aforementioned common support which is in turn anchorable to the fixed frame portion 7. With reference to Figure 1 , the unit 1 also comprises an inspection device 11 , preferably optical, specifically a camera, facing the rolling drum 10 (or another drum or conveyor located upstream of the rolling drum 10) to check the properties of the cigarettes (whether single or double) obtained by rolling the groups 200 of segments and, when necessary, cutting into two single-length cigarettes, in particular to check that the filter and tobacco segments are correctly spaced apart.

In an embodiment, the aforesaid adjustment means acting on the spacing guides can be driven by feedback control based on the information obtained from the optical inspection device 11 and processed by a processing unit.

This invention achieves the preset aim by providing a conveyor and a unit capable of operating in a very precise and efficient manner to produce cigarettes having an empty space between the filter and the tobacco segment.

Claims

1. A conveyor for rod-shaped articles, comprising a conveying surface provided with a succession of seats (4), preferably suction seats, for holding respective groups of segments (200) and for transversely advancing the groups of segments (200), wherein each seat (4) has a middle portion (4a) for receiving a middle segment (210) and a pair of opposite side portions (4b) for receiving respective side segments (220), wherein the conveyor (1) also comprises a pair of side compacting means (6) operating on the side portions (4b) of the seats (4) to progressively compact the side segments (220) towards the middle segment (210) as the conveying surface advances, and a pair of spacing guides (5; 5’; 5”) disposed between the middle portion (4a) and the side portions (4b) of the seats (4) to define a limit stop in the axial positioning of the side segments (220) and to set a predetermined distance between the middle segment (210) and the side segments (220).

2. The conveyor according to claim 1 , wherein each of the spacing guides (5, 5’, 5”) has an inside lateral surface (5a) and an outside lateral surface (5b) directed, respectively, towards the middle portion (4a) and the respective side portion (4b) of the seats (4) and wherein the spacing guides (5, 5’, 5”) each comprise at least one fixed spacing guide (5, 5’) securely anchorable to a fixed portion of a unit for assembling rod-shaped articles.

3. The conveyor according to claim 2, wherein the fixed spacing guides (5, 5’) have respective convergent entry portions (5d) made on the inside lateral surface (5a) so that the middle portion (4a) of the seats (4) converges in width along the feed direction.

4. The conveyor according to claim 3, wherein the outside lateral surfaces (5b) are planar for the full length of the spacing guides (5, 5’, 5”).

5. The conveyor according to claim 3, wherein the outside lateral surfaces (5b) have respective entry portions (5e) which are inclined, in particular convergent, so that each outside lateral surface (5b) defines, in cooperation with the respective compacting means (6), a substantially constant length of the side portions (4b) of the seats (4) at the entry portion (5e).

6. The conveyor according to any one of claims 2 to 5, wherein the inside lateral surfaces (5a) and the outside lateral surfaces (5b) are defined, for each spacing guide (5, 5’, 5”), by a single fixed spacing guide (5, 5’) preferably defined by a plate-shaped element.

7. The conveyor according to any one of claims 2 to 5, wherein each of the spacing guides (5, 5’, 5”) also comprises a movable spacing guide (5”) disposed externally of and juxtaposed with the respective fixed spacing guide (5, 5’) so that an inside surface of each fixed spacing guide (5, 5’) and an outside surface of the respective movable spacing guide (5”) define the size of the spacing between the middle segment (210) and the respective side segment (220); the movable spacing guides (5”) being provided with synchronous motion relative to the conveying surface and being preferably fixed to the conveying surface.

8. The conveyor according to claim 1 , wherein the inside lateral surfaces (5a) and the outside lateral surfaces (5b) are defined, for each spacing guide (5, 5’, 5”), by a single movable spacing guide, are provided with synchronous motion relative to the conveying surface and are preferably fixed to the conveying surface.

9. The conveyor according to any one of the preceding claims, wherein the seats (4) have suction holes on each middle portion (4a) and each of the side portions (4b); preferably the middle portion (4a) and the side portions (4b) of each suction seat (4) being defined by a single, uninterrupted suction seat (4).

10. The conveyor according to any one of claims 2 to 7, wherein the conveying surface is defined by the peripheral mantle of a conveying drum (3) and wherein the fixed spacing guides (5, 5’) are located on the outside of the conveying drum (3) in an externally uncovered angular sector.

11. The conveyor according to any one of the preceding claims, wherein the side compacting means (6) are movable synchronously with the conveying surface and operate on the side portions (4b) of the seats (4) with an axial movement to progressively compact the side segments (220) towards the middle segment (210), the compacting means (6) being preferably embodied as rotary discs rotatable about inclines axes so that a peripheral surface of the rotary disc moves progressively towards and away from the side portions (4b) of the seats (4).

12. The conveyor according to any one of the preceding claims, comprising adjustment means, preferably motor-driven, acting on the spacing guides (5, 5’, 5”) to vary a mutual distance between the spacing guides (5, 5’, 5”).

13. A unit for assembling cigarettes (100) of the type having an empty space (140) between filter (110) and tobacco segment (120), wherein the unit comprises:

- feed means (2) for feeding groups of segments (200), each group of segments (200) comprising a double segment (210), specifically a filter segment, and two side segments (220), specifically tobacco segments, disposed coaxially with the double segment (210) and axially spaced from the double segment (210);

- a conveyor (3) according to any one of the preceding claims, located downstream of the feed means (2) to receive the groups of segments (200) in such a way that the double segments (210) are released in the middle portions (4a) of the seats (4) and the side segments (220) are released in the side portions (4b) of the seats (4);

- a rolling unit, located downstream of the conveyor (3) and configured to receive the groups of segments (200) from the conveyor (3) and to join the segments (210, 220) of each group (200) to each other by means of one or more connecting strips (130) according to an axial spacing, defined by the conveyor (3), between the segments (210, 220) of each group of segments (220).

14. The unit according to claim 13, wherein the rolling unit comprises a rolling drum (10) and, at or downstream of the rolling drum (10), an inspecting device (11), preferably optical, for checking the spacing between the segments (110, 120; 210, 220) of each group of segments (200) or of each cigarette (100).

15. The unit according to claim 13 or 14, wherein: the conveyor (3) comprises adjustment means, preferably motor-driven, acting on the spacing guides (5, 5’, 5”) to vary a mutual distance between the spacing guides (5, 5’, 5”); it comprises a processing unit which is connected to the inspecting device (11) and to the adjustment means to control the adjustment means based on the information obtained from the inspecting device (11).

16. A method for assembling cigarettes, specifically of the type having an empty space (140) between filter (110) and tobacco segment (120) and preferably implemented using a conveyor (3) according to any one of claims 1-12 and/or a unit (1) according to any one of claims 13-15, comprising the following steps:

- feeding a succession of groups of segments (200) to a conveying surface provided with a succession of transverse seats (4), where each group of segments (220) comprises at least one double segment (210), specifically a filter segment (210), and two side segments (220), specifically tobacco segments, disposed coaxially with the double segment (210) and axially spaced from the double segment (210);

- disposing the segments (210, 220) of each group of segments (200) at a predetermined mutual axial distance from each other which is, in particular, adjusted as a function of a current format to be processed;

- after the step of disposing the segments (210, 220) of each group of segments (200) at a predetermined axial distance, rolling the segments (210, 220) in one or more connecting strips (130) in such a way as to obtain a single article where empty spaces (140) of predetermined size are defined between the segments (210, 220); wherein the step of disposing the segments (210, 220) of each group of segments (200) at a predetermined distance is carried out by transversely advancing the middle segment (210) and each side segment (220) on opposite sides of a respective spacing guide (5, 5’, 5”) and progressively compacting the side segment (220) towards the spacing guide (5, 5’, 5”) in such a way that the spacing guide (5, 5’, 5”) defines a limit stop for the axial positioning of the side segments (220) and determines the predetermined mutual axial distance.