ATBECHDEDKESFRGBGRITLILUNLSEMCPTIESILTLVFIROMKCYALTRBGCZEEHUPLSKBAHRIS..MTNORSMESMMAKHTNMD..........JBDM Ver 1.7.2 (20 November 2019) - 1100000/03636424EUROPEAN PATENT APPLICATIONA220200415EP19201700.220191007itenen20180000935420181011IT2020041520201620200415202016

B31C 5/00 20060101AFI20200206BHEP

A24C 5/46 20060101ALI20200206BHEP

B65H 45/22 20060101ALI20200206BHEP

deVERFAHREN UND VORRICHTUNG ZUM HERSTELLEN VON MEHRLAGIGEN HÜLSEN FÜR PRODUKTE DER TABAKINDUSTRIEenMETHOD AND MACHINE FOR MAKING MULTILAYER TUBES FOR TOBACCO INDUSTRY PRODUCTSfrPROCÉDÉ ET MACHINE DE PRODUCTION DE TUBES MULTICOUCHES POUR PRODUITS DE L'INDUSTRIE DU TABAC3G.D S.p.A.10095822461.G2475.EP2215Via Battindarno, 9140133 BolognaITGAMBERINI, Giulianoc/o G.D S.p.A. Via Battindarno 9140133 BOLOGNAITESPOSTI, Marcoc/o G.D S.p.A. Via Battindarno 9140133 BOLOGNAITBALDANZA, Nicolac/o G.D S.p.A. Via Battindarno 9140133 BOLOGNAITEUSEPI, Ivanc/o G.D S.p.A. Via Battindarno 9140133 BOLOGNAITFEDERICI, Luca-deceasedITBianciardi, Ezio101229088Bugnion S.p.A. Via di Corticella, 8740128 BolognaITALATBEBGCHCYCZDEDKEEESFIFRGBGRHRHUIEISITLILTLULVMCMKMTNLNOPLPTRORSSESISKSMTRBAMEKHMAMDTN

A machine for making multilayer tubes of the tobacco industry comprises: a first folding station (3, 4) configured to fold a first longitudinal strip (110) of the continuous web (100) onto a second longitudinal strip (120) of the web (100) to obtain a multilayer web; a forming station (5) for forming a continuous tube by continuously wrapping the multilayer web around a longitudinal axis; a cutting station for cutting the continuous tube into a succession of tubes (200); wherein the folding station (3, 4) has a first deflector edge (10) for deflecting the first longitudinal strip (110) and a second deflector edge (11) to deflect simultaneously the remaining longitudinal strip (120, 130) of the continuous web (100), the first and second deflector edges (10, 11) being angled to each other.

This invention relates to a method and a machine for making multilayer tubes of the tobacco industry.

Known in the tobacco industry is the need for tube-shaped elements of paper material, for example for use as components of traditional cigarettes (to make the filters, for example) or "HNB" (heat-not-burn) cigarettes. For increased strength, these tube-shaped elements are made with a multilayer structure.

Generally speaking, these multilayer tube-shaped elements are made by superposing and gluing two paper webs in such a way as to obtain, on one or both of the longitudinal edges, suitable joining zones intended to be spliced to each other to form a tube-like configuration.

Also, to obtain a shape that is as cylindrical as possible, the two webs are offset during superposing and gluing, so that, when the tube is formed, the splices between the corresponding end edges of the two layers are angularly spaced from each other about the axis of the tube itself.

These known production methods, however, have the disadvantage of not guaranteeing sufficient precision in the final shape of the tube, especially in terms of precise size and superposition of the two webs. In effect, if the two webs are of the wrong size or incorrectly positioned relative to each other, the final shape will likely be irregular, and the edges of the layers not properly juxtaposed, resulting in a poor connection in the splicing zones or in a tube with an incorrect diameter.

In this context, the basic technical purpose of this invention is to provide a method and a machine for making multilayer tubes of the tobacco industry to overcome the above mentioned disadvantages of the prior art.

More specifically, this invention has for an aim to provide a method and a machine for making multilayer tubes of the tobacco industry, capable of guaranteeing a high level of dimensional precision of the end product.

The technical purpose indicated and the aim specified are substantially achieved by a method and a machine for making multilayer tubes of the tobacco industry, comprising the technical features described in claims 1 and 15, respectively, and/or in one or more of the claims dependent thereon.

The invention is described below with reference to the accompanying drawings, which illustrate a non-limiting embodiment of it, in which:

Figure 1 shows a side view of a part of a machine according to this invention, for making tubes of the tobacco industry;
Figure 2 shows a side view of a portion of the machine of Figure 1;
Figure 3 shows a perspective view of the machine portion of Figure 2;
Figures 4 and 5 shows two components of the machine portion of Figures 2 and 3;
Figure 6 shows a detail of the machine portion of Figures 2 and 3, with some parts cut away in order to better illustrate others;
Figure 7 shows a transverse cross section of a multilayer tube that can be made by the machine and method according to this invention;
Figure 7A shows a detail from the cross section of Figure 7;
Figures 8 and 9 show two steps in the production of a multilayer web used to make the tube of Figure 7;
Figure 10 shows a detail of a sub-step of the method for making the tube of Figure 7;
Figure 11 shows a further component of the machine according to the invention.

With reference to the accompanying drawings, the numeral 1 denotes in its entirety a machine for making tubes of the tobacco industry according to this invention (only partly illustrated in the accompanying drawings).

The machine 1 comprises feed means 2 for feeding a continuous web 100 and configured to feed a continuous web 100 along a feed direction X parallel to the direction of extension of the web 100 and, along the feed path of the web 100, a first folding station 3, followed by another folding station 4. Each folding station 3, 4 is configured to fold a respective longitudinal strip of the web 100 onto a second longitudinal strip of the web 100 about a longitudinal fold line which is parallel to the feed direction X so as to obtain a multilayer web having at least two superposed layers.

Looking in more detail, the embodiment illustrated has two consecutive folding stations 3, 4 to fold respective longitudinal strips in such a way as to obtain a three-layer web. To obtain a two-layer web, however, only the first folding station 3 is necessary.

Downstream of the two folding stations 3, 4 there is also a forming station 5 for forming a continuous tube from the multilayer web. More in detail, the forming station 5 is configured for continuously wrapping the multilayer web itself around a longitudinal axis to form a continuous tube with a longitudinal splice.

Interposed between the folding stations 3, 4 and the forming station 5 there may be an uncoupling and/or tensioning station 6 operating to allow the continuous web 100 to move at different speeds upstream and downstream and/or to tension the web, for example with a "dandy roller" system.

Downstream of the forming station 5 there is a cutting station (not illustrated) operating on the continuous tube to make a succession of transverse cuts to obtain a succession of tubes 200 of the tobacco industry.

The term "tube of the tobacco industry" is used to denote a generic tubular element, made, for example, of paper, plastic or metal or combinations thereof, cylindrical in shape, internally hollow and open at both ends.

The tube may be used directly in the form thus made, in particular internally hollow, to define a segment of a cigarette (traditional, HNB or other type of cigarette) or it may be intended to contain filling material such as tobacco fibre, granules or other material suitable for heat-not-burn (HNB) technology. Generally, the length of the tube is less than the length of a standard cigarette because the tube is advantageously used to make a cigarette segment.

Figures 7-10 illustrate details of the structure of the tube 200 in transverse cross sections. In particular, Figure 7 shows the final configuration of the tube 200, where different layers can be seen (in the embodiment with the three-layer thickness), while figures 8 and 9 show the configurations after the first step of folding and after the second step of folding, respectively. The two steps of folding are carried out, respectively, on a first longitudinal strip 110 of the web 100, folded over onto a second longitudinal strip 120 of the web 100, and on a third longitudinal strip 130 of the web 100, folded over onto the second longitudinal strip 120 of the web 100 (or on the first longitudinal strip 110 after it has been folded). More specifically, the longitudinal strips 110, 130 subjected to folding are side strips of the web 100, folded flat against the middle strip 120 by folding about folding lines which are parallel to the direction of extension of the web 100 (perpendicular to the sheet in Figures 7-10).

Figures 7-10 also show a specific embodiment where the longitudinal strips 110, 130 are folded on the same side: that is to say, the second longitudinal strip 130 is folded over onto the first longitudinal strip 110, which had, in its turn, been previously folded over onto the middle longitudinal strip 120 of the web 100. In the context of this invention, however, the two longitudinal side strips 110, 130 might equally be folded on opposite sides, without departing from the inventive concept.

The details of Figures 7A and 10 are embodiment details showing the splicing zone where opposite lateral edges of the multilayer web are joined and the related recessed zone 140 (Figure 10) is made to accommodate a protruding splicing edge 160 (Figure 7A).

More specifically, the recessed zone 140 is obtained by retracting the corresponding edge of the first longitudinal strip 110 in such a way that the folding operations create a longitudinal cavity 150 (Figure 9) that can be compressed to form the recessed zone 140.

On the opposite lateral edge, the protruding splicing edge 160 is obtained by suitably adjusting the folding of the third longitudinal strip 130, specifically by laterally offsetting its respective fold line in such a way as to obtain a portion which extends beyond the width of the portion of web 100 that has already been folded (Figure 9)..

It is evident that both the recessed zone 140 and the protruding splicing edge 160 can be modified as a function of the operating parameters of the folding stations 3, 4, specifically the widths of the longitudinal strips 110, 120, 130 by suitably varying the position of the longitudinal fold lines.

Described in detail below are the means and procedures used for folding the longitudinal strips 110, 130 (or just one of them in the case of a two-layer tube). In particular, the following detailed description applies to the first folding station 3, since the second folding station 4 can advantageously be made in the same way.

The first folding station 3 has a first deflector edge 10 disposed and/or configured to deflect the first longitudinal strip 110 of the web 100, and a second deflector edge 11 disposed and/or configured to deflect the second longitudinal strip 120 of the web 100, and, more specifically, the remaining part of the web 100. The deflector edges 10, 11 are shown more clearly in Figures 4-6.

Advantageously, the deflector edges 10, 11 are angled to each other.

Looking in more detail, the second deflector edge 11 is straight and perpendicular to the feed direction X of the web 100, whilst the first deflector edge 10, which is also straight, is inclined to the second deflector edge 11 at an acute angle (α), preferably included between 40° and 85°,
and still more preferably, between 60° and 80°.

In a preferred embodiment and as illustrated in Figures 4-6, the deflector edges 10, 11 are peripheral edges of the same deflector element 12 which is preferably plate-shaped. More specifically, the deflector element 12 is plate-shaped at least at the parts of it defining the peripheral edges used for folding. This gives the deflector element 12 a flat shape suitable for folding the web.

The deflector element 12 is associated with a respective gluing device 20 operating on the first strip 110 and/or on the second strip 120 of the web 100 just upstream of folding the first strip 110 and preferably downstream of the second deflector edge 11 to deliver an adhesive substance suitable for holding the first strip 110 on the second strip 120 after folding.

In a variant embodiment not illustrated, the web 100 is pre-gummed on specific zones of its surface and the gluing device 20 is replaced by hot-melt or high-pressure adhesive activating means. The activating means may be disposed upstream of the folding zone (in the case of hot-melt glue) or downstream of the folding zone (in the case of high-pressure activated glue) to activate the adhesive present in the overlapping zone between the first and the second strip 110, 120 of the web 100.

Advantageously the first folding station 3 also comprises an auxiliary guide member 30 located downstream of the first deflector edge 10 to receive and guide the first longitudinal strip 110 of the web 100 as it leaves the first deflector edge 10 and to guide the first strip 110 while it is being folded. The auxiliary guide member 30 is configured to slidably receive the first longitudinal strip 110 of the web 100 as it leaves the first deflector edge 10 and to guide the first longitudinal strip 110 while it is being folded completely onto the second longitudinal strip 120.

Preferably, the auxiliary guide member 30 is planar and still more preferably, plate-shaped.

As shown in detail in Figure 6, the auxiliary guide member 30 and the first deflector edge 10 are disposed in such a way as to come into contact with respective opposite surfaces of the continuous web 100.

Further, the auxiliary guide member 30 has a guiding edge 31 which is preferably straight and inclined relative to the feed direction X of the web 100 in such a way as to progressively fold the first longitudinal strip 110 onto the second longitudinal strip 120 of the web 100. The guiding edge 31 is preferably disposed at an angle β of between 5° and 50° to the feed direction X. In the embodiment illustrated, the angle β is approximately 10°.

With reference to the accompanying drawings, the guide member 30 also has an end edge 32, disposed downstream of the guiding edge 31 and parallel to the feed direction X, at a position such as to substantially coincide with the free longitudinal edge of the first longitudinal strip 110 at the folded position.

In a preferred embodiment and as illustrated in the accompanying drawings, the deflector element 12 defines a positioning plane of the web 100 entering the folding station 3, whilst the auxiliary guide member 30 defines a positioning plane of the continuous web 100 leaving the folding station 3 (Figures 2, 3 and 6).

In an embodiment not illustrated, there is provided, upstream of the folding stations 3, 4, a creasing or scoring station which makes one or more crease lines or lines of weakness intended to coincide with fold lines at a folding station 3, 4. The creasing station may comprise, for example, a pair of opposed rollers, at least one of which is provided with a pair of discs or ridges which are axially spaced from each other to make corresponding parallel lines of weakness on the initial web.

Figure 11 shows a further component of the machine 1 according to the invention, specifically a stabilizing element 70 configured to stabilize the folds on the multilayer web after all the steps of folding have been carried out. More in detail, the stabilizing element 70 is disposed downstream of the second folding station 4 (or more generally speaking, downstream of the last folding station) and is shaped in such a way as to present one or more deviating edges 71, 72 transverse to the feed direction of the multilayer web. The deviating edges 71, 72 have the function of applying a flattening action on the folded edges of the multilayer web (labelled M in Figure 11) while the web undergoes a local change in its positioning plane at each deviating edge 71, 72. The multilayer web leaving the stabilizing element 70 thus has stable, well-defined folds which have lost any possible curvature that might negatively affect the shape stability of the multilayer web.

According to an advantageous aspect of the invention, for one or both of the folding stations 3, 4, at least one position detector 40 is provided downstream and/or upstream of the folding station 3, 4 to detect a transverse position of the multilayer web 100. In the embodiment illustrated, there is a single position detector 40 upstream of the first folding station 3 (only schematically illustrated in Figure 1); there may, however, be a plurality of position detectors 40 distributed along the feed line of the web.

The machine 1 also comprises a processing unit (not illustrated), connected to the position detector 40 and to the folding station 3, 4, and configured to vary one or more operating parameters of the folding station 3, 4, preferably the width and/or transverse position of the first and/or the third longitudinal strip 110, 130 relative to the second longitudinal strip 120 as a function of the transverse position detected. That way, it is possible to maintain a high precision tolerance and to compensate for any constructional imprecisions, and to vary the dimensions of the recessed zone 140 and of the protruding splicing edge 160 to modify the properties of the longitudinal splice of the continuous tube.

According to a further advantageous aspect of the invention, a device (not illustrated) is used to detect at least one diameter value of the continuous tube and/or of at least one tube 200 obtained by cutting the continuous tube. In this situation, the processing unit is also connected to the position detector to vary one or more operating parameters of at least one folding station 3, 4, preferably the width and/or transverse position of the first and/or the third longitudinal strip 110, 130 relative to the second longitudinal strip 120 as a function of the diameter value detected. This allows using feedback to operate on the folding stations 3, 4 to compensate for possible excessive deviations of the real diameter from a reference diameter.

The machine 1 may further comprise a centring device 50, located preferably upstream of the folding stations 3, 4 for setting a transverse position at least of the continuous web 100 entering the first folding station 3. Preferably, the processing unit is configured to operate also on the centring device 50 to vary, through the centring device 50, the transverse position of the entire continuous web 50 upstream of the folding stations 3, 4 as a function of the transverse position detected by the detecting device 40.

There may also be provided an adhesive presence and/or properties detector (not illustrated) - for example, a capacitive sensor - for detecting the presence and/or properties of the adhesive substance, interposed between the first and the second longitudinal strip 110, 120 and/or between the second and the third longitudinal strip 120, 130 of the continuous web 100.

In the embodiment illustrated in the accompanying drawings, at least one guiding device 60 is preferably provided downstream of each folding station 3, 4 to adjust the transverse position of the web leaving the station 3, 4.

Further, in an embodiment not illustrated, one or more of the folding stations 3, 4 comprises cooling means to prevent the deflector element 12 and/or the auxiliary guide member 30 from overheating as a result of the web sliding on them.

In use, the continuous web 100 is fed along the feed direction X, parallel to the direction of extension of the web 100, and then the first longitudinal strip 110 of the web 100 is folded onto the second longitudinal strip 120 about a respective fold line which is parallel to the feed direction X so as to obtain a multilayer web having two superposed layers. Optionally, the third longitudinal strip 130 of the web 100 is then folded onto the second longitudinal strip 120 (onto which the first longitudinal strip 110 had been folded) about a second fold line which is parallel to the feed direction X so as to obtain a multilayer web having three layers.

Next, the continuous tube is formed by continuously wrapping the multilayer web around a longitudinal axis, in particular by juxtaposing and splicing opposite lateral edges of the multilayer web (for example by joining the recessed portion 140 to the protruding splicing edge 160).

The continuous tube is then cut transversely to obtain a succession of tubes 200 of the tobacco industry.

Each step of folding is accomplished by deflecting the first longitudinal strip 110 of the web 100 around the respective first deflector edge 10 and simultaneously deflecting the second longitudinal strip 120 or, as the case may be, the remaining longitudinal strip, of the web 100 around the second deflector edge 11.

Whilst the deflection of the first longitudinal strip 110 produces a twisting action, or "screwing" motion of its positioning plane such that the first strip 110 is overturned onto the second strip 120, the deflection of the remaining part or longitudinal strip of the web 100 only changes the inclination of its positioning plane, specifically about an axis (which is substantially defined by the second deflector edge 11) perpendicular to the feed direction X. This change in the inclination of the positioning plane defines a "pitching action" at the front of the web, that is to say, a folding action up or down with reference to the feed direction X of the web 100.

This change in the inclination of the positioning plane, in conjunction with the folding of the first longitudinal strip 110, has the effect of optimizing the superposing geometry of the longitudinal strips, compensating for the greater length of the path that the first longitudinal strip 110 would have to travel in its folding movement if the remaining part of the web 100 were not deflected.

Thanks to this feature, the invention improves the geometric fit between the layers of the multilayer web, increasing its production precision and regularity.

A method for making multilayer tubes of the tobacco industry, comprising the following steps: - feeding a continuous web (100) along a feed direction (X) parallel to the direction of extension of the web (100);

- folding a first longitudinal strip (110) of the web (100) onto a second longitudinal strip (120) of the web (100) about a fold line which is parallel to the feed direction (X) so as to obtain a multilayer web having at least two partly superposed layers;

- forming a continuous tube by continuously wrapping the multilayer web around a longitudinal axis;

- cutting the continuous tube to obtain a succession of tubes (200) of the tobacco industry; wherein the step of folding is accomplished by deflecting the first longitudinal strip (110) of the web (100) around a first deflector edge (10) and by deflecting a remaining longitudinal strip (120, 130) of the web (100) around a second deflector edge (11), the first and second deflector edges (10, 11) being angled to each other.

The method according to claim 1, wherein the second deflector edge (11) is substantially straight and perpendicular to the feed direction (X).

The method according to claim 1 or 2, wherein the first deflector edge (10) is straight and inclined to the second deflector edge (11) at an acute angle (α) preferably included between 40° and 85° and still more preferably between 60° and 80°.

The method according to one or more of the preceding claims, wherein the first and second deflector edges (10, 11) are peripheral, and preferably incident, edges of a single deflector element (12), the deflector element (12) being preferably shaped like a plate at least at the peripheral edges.

The method according to one or more of the preceding claims, wherein the step of folding is also accomplished by an auxiliary guide member (30) located downstream of the first deflector edge (10) and configured to slidably receive the first longitudinal strip (110) of the web (100) as it leaves the first deflector edge (10) and to progressively guide the first longitudinal strip (110) while it is being folded completely onto the second longitudinal strip (120).

The method according to claim 5 when it depends on claim 4, wherein the auxiliary guide member (30) is planar and preferably has a plate-like configuration.

The method according to claim 5 or 6, wherein the auxiliary guide member (30) and the first deflector edge (10) are disposed relative to the continuous web (100) in such a way as to come into contact with respective opposite surfaces of the continuous web (100), and wherein the auxiliary guide member (30) has a guiding edge (31) which is preferably straight and inclined relative to the feed direction (X) in such a way as to progressively fold the first longitudinal strip (110) onto the second longitudinal strip (120) of the web (100).

The method according to one or more of the preceding claims, comprising, between the step of folding the first longitudinal strip (110) onto the second longitudinal strip (120) and the step of forming a continuous tube, a further step of folding a third longitudinal strip (130) of the continuous web (100) onto the first or the second longitudinal strip (110, 120) of the continuous web (100) in such a way as to form a three-layer web, the further step of folding being accomplished by deflecting the third longitudinal strip (130) of the continuous web (100) around a respective first deflector edge (10) and by deflecting a remaining part of the continuous web (100), specifically the previously superposed first and/or second longitudinal strip (110, 120), around a respective second deflector edge (11), the first and second deflector edges (10, 11) being angled to each other.

The method according to one or more of the preceding claims, wherein the first and/or the third longitudinal strip (110, 130) of the continuous web (100) is a side strip of the continuous web (100) and wherein the second longitudinal strip (120) is a middle strip of the continuous web (100).

The method according to one or more of the preceding claims, further comprising a step of detecting a transverse position of the continuous web (100) after and/or before the step of folding, by means of at least one position detector (40), and a step of varying one or more parameters of the step of folding, preferably the width and/or transverse position of the first and/or the third longitudinal strip (110.130) relative to the second longitudinal strip (120), as a function of the transverse position detected.

The method according to one or more of the preceding claims, further comprising a step of measuring at least one diameter of the continuous tube and/or of at least one tube (200) of the tobacco industry obtained by cutting the continuous tube, and a step of varying one or more parameters of the step of folding, preferably the width and/or transverse position of the first and/or the third longitudinal strip (110.130) relative to the second longitudinal strip (120), as a function of the at least one diameter measured.

The method according to one or more of the preceding claims, further comprising at least one step of setting a transverse position of the continuous web (100) before the step of folding the first longitudinal strip (110) of the continuous web (100) by means of a centring device (50).

The method according to one or more of the preceding claims, further comprising at least one step of applying an adhesive substance between the first and the second longitudinal strip (110, 120) and/or between the second and the third longitudinal strip (120, 130), and/or a step of activating an adhesive substance previously applied on the continuous web (100).

The method according to claim 4 or 5, wherein the deflector element (12) defines a positioning plane of the continuous web (100) before the step of folding and/or wherein the auxiliary guide member (30) defines a positioning plane of the continuous web (100) after the step of folding.

A machine for making multilayer tubes of the tobacco industry, specifically for implementing the method according to one or more of the preceding claims, comprising: - feed means (2) for feeding a continuous web (100) and configured to feed a continuous web (100) along a feed direction (X) parallel to the direction of extension of the continuous web (100);

- at least one first folding station (3, 4) configured to fold a first longitudinal strip (110) of the web (100) onto a second longitudinal strip (120) of the web (100) about a fold line which is parallel to the feed direction (X) so as to obtain a multilayer web having at least two partly superposed layers;

- a forming station (5) for forming a continuous tube by continuously wrapping the multilayer web around a longitudinal axis;

- a cutting station for cutting the continuous tube to obtain a succession of tubes (200) of the tobacco industry; wherein the at least one folding station (3, 4) has a first deflector edge (10) disposed and/or configured to deflect the first longitudinal strip (110) of the continuous web (100), and a second deflector edge (11) disposed and/or configured to deflect a remaining longitudinal strip (120, 130) of the web (100), the first and second deflector edges (10, 11) being angled to each other.

The machine according to claim 15, wherein the second deflector edge (11) is straight and perpendicular to the feed direction (X).

The machine according to claim 15 or 16, wherein the first deflector edge (10) is straight and inclined to the second deflector edge (11) at an acute angle (α) preferably included between 40° and 85° and still more preferably between 60° and 80°.

The machine according to one or more of claims 15 to 17, wherein the first and second deflector edges (10, 11) are peripheral edges of a single deflector element (12), the deflector element (12) being preferably shaped like a plate.

The machine according to one or more of claims 15 to 18, wherein the at least one first folding station (3, 4) also comprises an auxiliary guide member (30) located downstream of the first deflector edge (10) and configured to slidably receive the first longitudinal strip (110) of the web (100) as it leaves the first deflector edge (10) and to progressively guide the first longitudinal strip (110) while it is being folded completely onto the second longitudinal strip (120).

The machine according to claim 19 when it depends on claim 18, wherein the auxiliary guide member (30) is planar and preferably has a plate-like configuration.

The machine according to claim 19 or 20, wherein the auxiliary guide member (30) and the first deflector edge (10) are disposed in such a way as to come into contact with respective opposite surfaces of the continuous web (100), and wherein the auxiliary guide member (30) has a guiding edge (31) which is preferably straight and inclined relative to the feed direction (X) in such a way as to progressively fold the first longitudinal strip (110) onto the second longitudinal strip (120) of the continuous web (100).

The machine according to one or more of claims 15 to 21, further comprising at least one position detector (40) downstream and/or upstream of the at least one first folding station (30) for detecting a transverse position of the continuous web (100), and a processing unit connected to the position detector (40) and to the folding station (3, 4) and configured to vary one or more operating parameters of the folding station (3, 4), preferably the width and/or transverse position of the first longitudinal strip (110) relative to the second longitudinal strip (120) of the continuous web (100), as a function of the transverse position detected.

The machine according to one or more of claims 15 to 22, further comprising a second folding station (4) located downstream of the first folding station (3) and configured to fold a third longitudinal strip (130) of the continuous web (100) onto the second longitudinal strip (120) of the continuous web (100) in such a way as to form a three-layer web and wherein the second folding station (4) has a respective first deflector edge (10) disposed and/or configured to deflect the third longitudinal strip (130) of the continuous web (100), and a respective second deflector edge (11) disposed and/or configured to deflect the second longitudinal strip (120) of the web, the first and second deflector edges (10, 11) of the second folding station (4) being angled to each other.

The machine according to one or more of claims 15 to 23, further comprising a device for measuring at least one diameter of the continuous tube and/or of at least one tube (200) of the tobacco industry obtained by cutting the continuous tube, and wherein the machine (1) further comprises a processing unit connected to the measuring device and to the at least one first folding station (3, 4) to vary one or more operating parameters of the folding station (3, 4), preferably the width and/or transverse position of the first and/or the third longitudinal strip (110, 130) relative to the second longitudinal strip (120) of the continuous web, as a function of the at least one diameter measured.

The machine according to one or more of claims 15 to 24, further comprising a centring device (50) located upstream of the at least one first folding station (3, 4) for setting a transverse position of the continuous web (100).

The machine according to one or more of claims 15 to 25, further comprising at least one gluing device (20) for applying an adhesive substance between the first and the second longitudinal strip (110, 120) and/or between the second and the third longitudinal strip (120, 130) of the continuous web, and/or a device for activating by heat or pressure an adhesive substance previously applied on the continuous web (100), the device for activating by heat or pressure being located downstream of the at least one first folding station (3, 4).

The machine according to claim 26, further comprising a detector, preferably a capacitive sensor, located downstream of the at least one first folding station (3, 4), for detecting the presence and/or properties of the adhesive substance, interposed between the first and the second longitudinal strip (110, 120) and/or between the second and the third longitudinal strip (120, 130) of the continuous web (100).

The machine according to one or more of claims 15 to 27, wherein the deflector element (12) defines a positioning plane of the continuous web (100) entering the folding station (3, 4) and/or wherein the auxiliary guide member (30) defines a positioning plane of the continuous web (100) leaving the folding station (3, 4).