Patent Description:
Especially in the last few years, the need to make small tubular elements for the above use has been growing, guaranteeing high productivity and very advanced automation.

Normally, the external wrappers for smoking articles have a substantially cylindrical or truncated cone shape and are made of non-toxic paper that is very thin and fragile, and is therefore very difficult to treat mechanically.

Apparatuses are known for the production of tubular elements, in particular straws, by winding, in a helicoidal manner, one or more strip-like elements of flexible material, preferably paper, partly overlapping each other, around a forming member, called a forming pin, which is substantially cylindrical in shape, see for example document <CIT>.

However, these known apparatuses have the disadvantage that they are excessively complex and produce tubular elements with peripheral walls that are too thick, and therefore suitable to make straws but not suitable to make smoking articles.

There is therefore a need to make an apparatus for automatically producing tubular elements to make both smoking articles and products for food use, which can overcome at least one of the disadvantages of the state of the art.

To do this it is necessary to solve the technical problem of automatically making tubular elements with a material that is very thin, fragile and difficult to process, such as paper, while still maintaining high productivity, in the order of over <NUM>,<NUM> pieces/hour.

In particular, one purpose of the present invention is to provide an apparatus and to perfect a method for automatically producing tubular elements which can be used for making smoking articles and/or products for food use.

Another purpose of the present invention is to provide an apparatus and to perfect a method for automatically producing tubular elements, especially of small sizes and very light, which are highly efficient, versatile and which allow to obtain high productivity.

Another purpose of the present invention is to provide an apparatus and to perfect a method for automatically producing modular elements which can be integrated into a more complex machine, also able to perform other work on the tubular elements, for example to package finished smoking articles.

In accordance with the above purposes, and to resolve the technical problem disclosed above in a new and original way, also achieving considerable advantages compared to the state of the prior art, an apparatus according to the present invention for automatically producing tubular elements to make smoking articles and/or products for food use comprises a feed unit for feeding, in sequence and one at a time, a plurality of sheets in a flat condition, and a forming unit disposed downstream of the feed unit and configured to form the tubular elements starting from the sheets.

In accordance with one aspect of the present invention, the forming unit comprises one or more forming devices, each of which in turn comprises both a forming pin rotatable around an axis of rotation thereof and having an external surface with a truncated cone or cylindrical shape, coaxial to said axis of rotation, and also holding means for temporarily holding one of the sheets against the external surface. Movement means are configured both to move the one or more forming devices along a work path, and also to make the forming pins rotate around the respective axis of rotation. Furthermore, contrast means are disposed in a certain fixed position along the work path to cooperate with each of the sheets in order to fold them in such a way that they are at least partly wound each one around a corresponding forming pin in order to form one of the tubular elements.

In accordance with one aspect of the present invention, the forming device is configured to take the sheet, which is held against the external surface of the forming pin by the holding means, against the contrast means while the respective forming pin is made to rotate, so as to cause the at least partial winding of the sheet on the external surface of the forming pin during the movement of the forming device along the work path.

In accordance with another aspect of the present invention, the holding means comprise a suction system configured to suction air through a plurality of suction holes present in the external surface of the forming pin so as to selectively hold one of the sheets against the external surface, keeping it adherent thereto.

In accordance with another aspect of the present invention, the holding means comprise, alternatively or in addition to the suction system, a jaw that can be selectively driven to hold one of the sheets against the external surface, keeping it adherent thereto.

In accordance with another aspect of the present invention, the contrast means comprise a first contrast and guide member and a second contrast and guide member, both fixed and disposed on opposite parts with respect to the work path. The first and second contrast and guide members define a hollow space between them, inside which the forming pin can slide, preferably with minimum clearance.

In accordance with another aspect of the present invention, the first contrast and guide member and the second contrast and guide member are disposed in succession along the work path.

In accordance with another aspect of the present invention, the feed unit comprises, disposed in sequence along a feed path upstream of the forming unit, a shaping device configured to obtain shapes from a strip which correspond to the sheets still joined together, first advance means configured to make the strip advance along the feed path, a cutting device configured to cut the strip and make, by separating them, the sheets, and second advance means configured to make each of the sheets individually advance in a flat condition toward the forming unit.

In accordance with another aspect of the present invention, the work path of the forming unit is closed in a loop, preferably circular in shape or having at least one rectilinear segment.

In accordance with another aspect of the present invention, the apparatus also comprises an extraction member configured to extract one tubular element at a time from the respective forming device.

In accordance with another aspect of the present invention, the apparatus also comprises, along the work path, gluing means configured to apply an adhesive material on each of the sheets, if this is not already present on them.

In accordance with another aspect of the present invention, the apparatus also comprises a drying station configured to dry the adhesive material after the tubular element has been formed.

The apparatus according to the present invention has the advantage of being extremely versatile and being able to achieve high productivity, in the order of more than <NUM>,<NUM> tubular elements/hour.

In accordance with another aspect of the present invention, a method is perfected for automatically producing tubular elements to make smoking articles and/or products for food use, comprising in sequence a feed step in which several sheets in a flat condition are fed, in sequence and one at a time, toward a forming unit configured to form the tubular elements starting from said sheets.

The method comprises, in sequence, a positioning step in which each of the sheets is positioned and temporarily held on an external surface of a forming pin of a forming device, the forming pin being rotatable around an axis of rotation thereof, and a movement step in which the forming device, together with the held sheet, is moved along a work path.

In accordance with one aspect of the present invention, the method also comprises a forming step in which the forming device takes the sheet first against contrast means which are disposed in a certain fixed position along the work path, while the forming pin, together with the held sheet, rotates around its axis of rotation so as to cause the folding of two flaps of the sheet, in such a way that the latter is at least partly wound on the external surface of the forming pin.

In accordance with one aspect of the present invention, the method also comprises a forming step in which the forming pin, together with the held sheet, while it rotates around its axis of rotation along the work path, takes a first zone of a first of the two flaps to overlap with a second zone of a second of the two flaps, at least one of said first and second zones being provided with, or on which there is disposed, an adhesive material.

In accordance with another aspect of the present invention, each of the sheets comprises an internal face configured to contact the external surface of the forming pin, a first lateral edge adjacent to which there is the first zone which has, or on which there is deposited, the adhesive material, and a second lateral edge adjacent to which there is, on an external face opposite the internal face, the second zone, which is configured to be contacted by the first zone through overlapping. This overlapping is created by means of the rotation of the forming pin around its own axis of rotation.

In accordance with another aspect of the present invention, the forming step comprises a first folding step in which the forming device with the held sheet is made to advance along the work path in such a way that one of the two flaps is taken against a first contrast and guide member of the contrast means in order to fold it against said external surface, and a subsequent second folding step in which the forming device is made to advance further along the work path in such a way that the other of the two flaps is taken against a second contrast and guide member of the contrast means in order to fold it against the external surface of the forming pin.

With reference to <FIG>, an apparatus <NUM> according to the present invention is configured to produce tubular elements <NUM> (<FIG>) in a completely automated manner, to make smoking articles and/or products for food use.

In accordance with possible embodiments of the present invention, the apparatus <NUM> (<FIG>) can be part of a more complex machine, not shown in the drawings, which can comprise other apparatuses or stations for working the tubular elements <NUM>.

Before describing the apparatus <NUM> in detail, in order to better understand the present invention, we will now describe a single tubular element <NUM>.

In relation to the sector for which it is intended, the tubular element <NUM> can be made with different materials, for example: a) to make smoking articles, the material can be very thin and light paper, such as cigarette papers; b) for the food sector, paper made sufficiently impermeable, or another already impermeable material, can be used.

Each tubular element <NUM> (<FIG>) is obtained from a corresponding sheet <NUM> (<FIG> and <FIG>), in a flat condition, which in turn is obtained, for example, from a strip <NUM> (<FIG>) which can be fed along a feed path PA in any known manner, for example by unwinding it from a reel not shown in the drawings.

The strip <NUM> can be of the type commonly on the market, already provided with a line, or zone, in which there is a very thin layer of adhesive material. This line is adjacent to one of the edges of the strip <NUM> and is present along the entire longitudinal development thereof.

Alternatively, the adhesive material, instead of being present on the strip <NUM>, can be applied directly on the sheets <NUM> during a step of forming the tubular elements <NUM>, as will be described in detail below.

We must clarify that the adhesive material can consist of any suitable material whatsoever, for example a vinyl glue, or natural gum Arabic, for example of the type that can be activated in the presence of water, or a glue of the type that is sensitive to pressure, also known to the people of skill in the art with the term "pressure-sensitive".

Each sheet <NUM> (<FIG>) is substantially small in size and has, for example, a base comprised between about <NUM> and about <NUM> and a height comprised between about <NUM> and about <NUM>, and it can have the shape of an isosceles trapezoid, or a rectangle, depending on whether a corresponding tubular element <NUM> with a truncated cone or cylindrical shape is to be obtained, respectively.

In particular, each sheet <NUM> (<FIG>) comprises: a first internal face <NUM>, which will then constitute the internal surface of the tubular element <NUM>; a second external face <NUM>, which will then constitute the external surface of the tubular element <NUM>; a first lateral edge <NUM> adjacent to which there is a first zone <NUM> which can have, or on which there can be deposited, the adhesive material; and a second lateral edge <NUM> adjacent to which there is a second zone <NUM> configured to overlap with the first zone <NUM>. Please note that the first zone <NUM> corresponds to the portion of the line of the strip <NUM> in which the adhesive material can be present, or not.

The apparatus <NUM> essentially comprises a feed unit <NUM> (<FIG>) for feeding a plurality of sheets <NUM> in sequence and one at a time, and a forming unit <NUM> (<FIG>) disposed downstream of the feed unit <NUM> and configured to form the tubular elements <NUM> starting from corresponding sheets <NUM> in a flat condition. Please note that in the embodiments described here, the sheets <NUM> have the shape of an isosceles trapezoid, whereby each tubular element <NUM> will have a truncated cone shape.

With reference to <FIG>, the feed unit <NUM> comprises, disposed in sequence and from bottom to top, along the feed path PA of the strip <NUM>, a shaping device <NUM>, a pair of dragging rollers <NUM>, a cutting device <NUM> and a transport member <NUM>. The drive of the shaping device <NUM>, the dragging rollers <NUM>, the cutting device <NUM> and the transport member <NUM> is performed by respective actuation elements, for example provided with electric motors, and/or or by other actuators of a known type and not shown in the drawings.

In the examples given here, the feed path PA develops in a substantially vertical direction. It is clear that, according to other possible embodiments, not shown in the drawings, the feed path PA could develop in a horizontal direction, or a direction inclined with respect to a horizontal plane, or one having a curvilinear development, or it could have other suitable shapes.

The shaping device <NUM> is disposed on the feed path PA so that the strip <NUM> substantially passes through it in a central zone thereof. For example, the shaping device <NUM> is provided with at least one cutting member <NUM> which is configured to perform a shaping of the strip <NUM> according to a specific geometry and produce a plurality of shapes S, each having the form of one sheet <NUM> and contiguous to each other, without a break in continuity, in correspondence with the respective larger and smaller bases, respectively, of the isosceles trapezoids thus formed. Please note that the operation of shaping the strip <NUM> also produces a plurality of waste portions, or scraps, which are advantageously suctioned by the same shaping device <NUM>, for example by means of suction means, of a known type and not shown in the drawings. Furthermore, the shaping device <NUM> is disposed in such a way that the portion of strip <NUM> which is cut and removed is the one on the opposite part with respect to the possible lateral zone on which the adhesive material is present or will later be applied.

As shown in <FIG>, the feed path PA along which the strip <NUM> is made to advance is inclined by an angle α with respect to a generic reference direction Y, for example vertical. The angle α is chosen so that the external edge of the strip <NUM> defines one of the two oblique sides of the isosceles trapezoids which will then define the corresponding sheets <NUM>, and it can be, for example, of approximately <NUM>°. Consequently, the inclination of the cut performed by the cutting device <NUM> has to be specular with respect to the angle α. Please also note that the angle α can be adjusted according to the specific operating requirements of the apparatus <NUM>.

The transport member <NUM> consists, for example, of a conveyor belt provided with a plurality of suction holes <NUM> which have the function of selectively holding each sheet <NUM> against the conveyor belt along an ascending rectilinear segment thereof. Therefore, the transport member <NUM> has the function of making the sheet <NUM> advance, detaching it from the strip <NUM> already shaped, after the cut has been performed, and of delivering, in a known manner, each sheet <NUM> to the forming unit <NUM> keeping it in a flat and substantially vertical position.

Please note that in order to achieve the immediate detachment of the sheet <NUM> from the strip <NUM>, after the cut has been performed, the transport member <NUM> has to have a speed of advance greater than the dragging speed imparted to the strip <NUM> by the dragging rollers <NUM> along the feed path PA.

The forming unit <NUM> (<FIG>) comprises a plurality of operating stations disposed in sequence along a work path PL, among which at least:.

In accordance with one aspect of the present invention, the work path PL of the forming unit <NUM> is closed in a loop and has, for example, a circular shape (<FIG>, <FIG> and <FIG>).

According to other embodiments of the present invention, such as the one shown in <FIG>, <FIG> and <FIG> for example, the work path PL, although advantageously closed in a loop, has at least one rectilinear segment.

As shown in <FIG>, <FIG> and <FIG>, the forming unit <NUM> comprises a disk-shaped rotating member <NUM> which defines, in correspondence with its periphery, the work path PL and which is rotatable around a main axis of rotation R1 of its own, for example vertical. The rotation of the rotating member <NUM> can occur, for example, with constant angular increments or pitches β. This allows to simultaneously perform, in correspondence with each station of the forming apparatus <NUM>, a different operation on the sheets <NUM>, or on the tubular elements <NUM>, consequently increasing the overall productivity of the apparatus <NUM>.

In the embodiment shown in <FIG> the angular pitch β is <NUM>°, but it can also be different, that is, larger or smaller, depending on the design and construction choices of the apparatus <NUM>. The rotation of the rotating member <NUM> is achieved by means of movement means <NUM> (<FIG>), which can be of any known type whatsoever and can comprise, for example, an electronically controlled stepper motor.

Please note that the orientation of the main axis of rotation R1, as well as the disposition of the forming unit <NUM>, is coordinated with the orientation of the feed path PA of the strip <NUM>. For example, according to embodiments not shown in the drawings, with a feed path PA that is substantially horizontal, or inclined with respect to a horizontal plane, the main axis of rotation R1 will also be concordant with such orientation.

The forming unit <NUM> comprises one or more forming devices <NUM>, which in the example given here are eight, which are mounted on the rotating member <NUM> with the same uniform angular intervals β (<FIG>) along the work path PL. Furthermore, each forming device <NUM> can rotate around an axis of rotation thereof, or secondary axis of rotation, R2, parallel to the main axis of rotation R1.

The movement means <NUM> are configured to also be able to make each forming device <NUM> selectively rotate around its axis of rotation R2, as will be described in detail below. For example, the movement means <NUM> can comprise an epicyclic gearing and/or an electric or mechanical cam mechanism, of a known type and not shown in the drawings, associated with each forming device <NUM>.

Each forming device <NUM> comprises both a forming pin <NUM> (<FIG>), coaxial to the secondary axis of rotation R2, internally hollow and having an external surface with a truncated cone or cylindrical shape, which reproduces the shape of the tubular element <NUM> (<FIG>) to be produced, and also holding means, described below and configured to temporarily and selectively hold a respective sheet <NUM> against the external surface of the forming pin <NUM> (figs. from <NUM> to <NUM>). As shown in <FIG>, in the event that the forming pin <NUM> has a truncated cone shape, its part with the largest diameter is disposed close to the rotating member <NUM>, that is, upward in the example given here.

In accordance with another aspect of the present invention, the holding means comprise, for each forming device <NUM>, a jaw <NUM> (<FIG>, <FIG> and from <NUM> to <NUM>), disposed outside the respective forming pin <NUM> and parallel to the secondary axis of rotation R2 thereof, the jaw <NUM> can be selectively driven to hold the sheet <NUM> against the external surface of the same forming pin <NUM>. The selective opening and closing of the jaw <NUM> is achieved, for example, by means of a dedicated actuator <NUM> (<FIG>), which can be associated with the forming pin <NUM> or with the rotating member <NUM>. In addition, or as an alternative, to the jaw <NUM>, the holding means comprise a suction system configured to suction air through a plurality of suction holes <NUM> present in the external surface of the forming pin <NUM>, so as to selectively hold one sheet <NUM> at a time against the external surface, keeping the sheet <NUM> adherent thereto.

Please note that each sheet <NUM> coming from the feed unit <NUM> and delivered to the corresponding forming device <NUM> is positioned asymmetrically with respect to the position of the jaw <NUM> (<FIG>, <FIG>), that is, with a first flap thereof, the one associated with the first lateral edge <NUM>, which protrudes further from the forming pin <NUM> compared to a second flap associated with the second lateral edge <NUM>.

The forming station <NUM> (<FIG>, <FIG>) comprises a first contrast and guide member <NUM> and a second contrast and guide member <NUM>, both mounted on a fixed structure of the apparatus <NUM>, not shown in the drawings, and disposed in a certain position with respect to the work path PL and on opposite parts with respect thereto. The two contrast and guide members <NUM> and <NUM> are configured to cooperate with the two lateral flaps of each sheet <NUM> to at least partly fold them around a corresponding forming pin <NUM> in order to then form one of the tubular elements <NUM>, as will be described in detail below.

In accordance with another aspect of the present invention, the first contrast and guide member <NUM> is disposed between the work path PL and the main axis of rotation R1 (<FIG>), and comprises a first head shoulder 35a (<FIG>) and an associated first guide surface 35b. The second contrast and guide member <NUM> is disposed outside the work path PL with respect to the main axis of rotation R1 (<FIG>), and comprises a second head shoulder 36a (<FIG>) and an associated second guide surface 36b. Seen from the front (<FIG>), the two guide surfaces 35b and 36b are parallel to the external surface of each forming pin <NUM>.

Some embodiments of the present invention can provide that the two guide surfaces 36a and 36b are positioned with respect to the work path PL in such a way as to define a hollow space <NUM> between them (e.g. <FIG>) with a substantially constant width, inside which each forming device <NUM> can slide with minimum clearance with respect to the corresponding forming pin <NUM>.

Furthermore, along the work path PL, the first head shoulder 35a (<FIG>) and the associated first guide surface 35b are disposed upstream of the second head shoulder 36a and the associated second guide surface 36b, that is, closer to the feed station <NUM> (<FIG>). In this way, by making each forming device <NUM> advance with the respective held sheet <NUM> along the work path PL (clockwise in <FIG> and <FIG>, and from left to right in <FIG> and <FIG>) first the second flap of the sheet <NUM>, that is, the least protruding one, is folded, which, meeting the first shoulder 35a, folds against the external surface of the forming pin <NUM>, substantially assuming the shape of a J, and then the first flap, that is, the most protruding one, is folded which, meeting the second shoulder 36a, also folds against the external surface. As will be described in detail below, the forming of the tubular element <NUM> is then completed by the rotation of the forming pin <NUM> around the respective secondary axis of rotation R2, while this advances along the work path PL.

With the two contrast and guide members <NUM> and <NUM> there are associated a first presser member <NUM> and a second presser member <NUM>, respectively, which are configured to exert a certain radial pressure on the sheet <NUM> with the passing of the forming pin <NUM> on which the latter is already at least partly wound.

The angular distance between the two presser members <NUM> and <NUM> (<FIG>) is exactly the same as an angular interval β, whereby when a forming device <NUM> is in correspondence with the first presser member <NUM>, another forming device <NUM> is in correspondence with the second presser member <NUM>.

In particular, the first presser member <NUM> (<FIG>) comprises a first presser roller <NUM> mounted freely rotatable at one end of a first lever <NUM>, which is pivoted on the fixed structure of the apparatus <NUM> and conditioned by a first spring <NUM> (<FIG>). The second presser member <NUM> comprises a second presser roller <NUM> mounted freely rotatable at one end of a second lever <NUM>, pivoted on the fixed structure of the apparatus <NUM> and conditioned by a second spring <NUM>.

The two presser rollers <NUM> and <NUM> are shaped and positioned in such a way as to contact, for their entire height, each sheet <NUM> (<FIG>) held against the external surface of a forming pin <NUM>, when the latter passes in front of the same presser rollers <NUM> and <NUM> moving along the work path PL. Furthermore, the first and second springs <NUM> and <NUM> (<FIG>) are calibrated so that the presser members <NUM> and <NUM> impart a slight pressure on each sheet <NUM> against the corresponding forming pin <NUM>.

In the example given here, the two presser rollers <NUM> and <NUM> have their axis of rotation inclined in such a way that their cylindrical surfaces adapt precisely to the truncated cone shape of the forming pin <NUM> (in <FIG>, only the first presser roller <NUM> can be seen, by way of example).

Alternatively, in accordance with other embodiments of the present invention not shown in the drawings, the presser rollers <NUM> and <NUM> may not be inclined, but have a peripheral surface mating with the shape of the forming pin <NUM>.

In accordance with another embodiment of the present invention, if a water-activated vinyl glue is present on the first zone <NUM> of the sheet <NUM>, advantageously the first presser roller <NUM> is made of a material which allows it to be kept humidified, in any known manner whatsoever. In this case, the first presser roller <NUM> is configured, in addition to exert a certain pressure on the sheet <NUM>, also to humidify the zone of contact therewith, which corresponds to the second zone <NUM> which will then go below the first zone <NUM>, so as to activate the vinyl glue during the operation of forming the tubular element <NUM>, as will be described in detail below.

In accordance with another embodiment of the present invention, shown in <FIG>, if no adhesive material is present on the first zone <NUM>, it is provided that the forming unit <NUM> also comprises a gluing unit <NUM>, disposed in the forming station <NUM>, in correspondence with the second contrast and guide member <NUM>, and configured to apply a certain quantity of adhesive material on each first zone <NUM> of a sheet <NUM>.

For example, the gluing unit <NUM> comprises: a glue-spreading roller <NUM> of the rotary type, impregnated with glue or other adhesive material, tangential to which there is disposed a fixed scraper <NUM>; an applicator member <NUM> of the rotary type provided with spreading radial blades <NUM>; and a movement mechanism <NUM>, which are driven by respective electric motors and/or actuators, of a known type and not shown in the drawings.

The movement mechanism <NUM> is disposed in front of the first presser roller <NUM> in a through aperture <NUM> created in the second contrast and guide member <NUM>, whereby the latter is divided into two portions 36c and 36d, the first of which, together with the first contrast and guide member <NUM>, forms the hollow space <NUM>.

In the example given here, the movement mechanism <NUM> comprises a lever <NUM> pivoted on a pin <NUM> which is mounted on the fixed structure of the apparatus <NUM>. The lever <NUM> comprises a contact plate <NUM> configured to contact the external face <NUM> of the first flap of each sheet <NUM> and provided with suction means, of a known type and not shown in the drawings, which are configured to temporarily hold such first flap of the sheet <NUM>, for example for a few milliseconds.

The lever <NUM> has a length such as to allow the first zone <NUM> to protrude therefrom, when the first flap of the sheet <NUM> is held by the suction means; this is necessary for a correct glue spreading operation to be performed by one of the radial blades <NUM> of the applicator member <NUM>.

Furthermore, the lever <NUM> is selectively and alternately mobile, commanded by an associated actuator of a known type and not shown in the drawings, between a first operating position, in which it is with the contact plate <NUM> aligned with the second guide surface 36b of the second contrast and guide member <NUM>, and a second operating position, in which, holding the first flap of the sheet <NUM>, it is rotated by a certain angle, for example of about <NUM>°, so that the first zone <NUM> of the sheet <NUM> is in correspondence with the spreading radial blades <NUM> of the applicator member <NUM>. For example, the adhesive material used in this case can be a natural vinyl glue or rubber of the pressure-sensitive type.

Therefore, the apparatus <NUM> has the advantage of being very versatile and of having high productivity, with a cycle time of about <NUM> seconds, thus producing about <NUM>,<NUM> tubular elements <NUM> per hour.

The apparatus <NUM> also comprises a central control unit of a known type and not shown in the drawings, which is configured to command and coordinate the drive of the feed unit <NUM> and of the forming unit <NUM>, as well as of the respective operating components.

The operation of the apparatus <NUM> described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

We must clarify that what has been described for a single sheet <NUM> is valid cyclically for each of the sheets <NUM> with which the tubular elements <NUM> are obtained.

In an initial preparation step, the central control unit is configured and prepared to control and coordinate the drive of the feed unit <NUM>, of the forming unit <NUM> and of their operating components.

In a feed step, the feed unit <NUM> feeds one sheet <NUM> at a time, obtained from the strip <NUM>, toward the forming unit <NUM> along a feed path PA.

The feed step comprises the following operating sub-steps:.

Please note that during the transport and delivery step, the rotating member <NUM> is temporarily stationary, for example for a few tens of milliseconds, and one of the forming devices <NUM> is in a receiving position with the corresponding jaw <NUM> in an open condition.

In a subsequent positioning step (<FIG>), the sheet <NUM> in a flat condition is disposed substantially vertical and tangential to the external surface of a forming pin <NUM> (<FIG>) of a corresponding forming device <NUM>. Then, in this position, the jaw <NUM> is closed, so as to hold the sheet <NUM> against the external surface of the forming pin <NUM>. In particular, as previously described, the sheet <NUM> is blocked by the jaw <NUM> in an asymmetrical position with respect to the forming pin <NUM>, with the first flap, associated with the first lateral edge <NUM>, protruding more than the second flap, associated with the second lateral edge <NUM>.

Subsequently, in a movement step, the movement means <NUM> make the forming device <NUM> advance along the work path PL until it reaches the first head shoulder 35a.

Then an actual forming step begins (shown schematically in figs. from <NUM> to <NUM>), in which each tubular element <NUM> is formed thanks to the combination of the advance of each forming pin <NUM> with the respective held sheet <NUM> along the work path PL and the rotation of the forming pin <NUM> with the respective held sheet <NUM> with respect to the respective secondary axis of rotation R2. During this forming step, the suction system also contributes, through the air suctioned through the suction holes <NUM> of the forming pin <NUM>, to hold the sheet <NUM> so as to keep it adherent to the external surface of the forming pin <NUM>, as the sheet <NUM> is gradually wound thereon.

In particular, the forming step comprises, in sequence, the following operating sub-steps:.

Once the forming step has been completed, in a subsequent drying step the forming device <NUM> in question is transported in correspondence with the drying station <NUM>, where the glue is completely dried.

Finally, in an extraction step, the forming device <NUM> in question is transported in correspondence with the extraction station <NUM>, where an extraction member <NUM> extracts the tubular element <NUM> from the forming pin <NUM>.

In the event that the first zone <NUM> is not already provided with the adhesive material, a gluing step is provided, in which the gluing unit <NUM> is driven to apply a layer of adhesive material on the first zone <NUM> of the sheet <NUM>. This gluing step occurs in conjunction with the first temporary stop sub-step, that is, when the forming device <NUM> is in correspondence with the first presser roller <NUM>.

For example, in this gluing step, the movement mechanism <NUM> lifts the first flap of the sheet <NUM> and takes it in correspondence with the applicator member <NUM>, which applies the adhesive material by means of one of the radial blades <NUM>.

Please note that, in this case, the first flap of the sheet <NUM> may not have already been folded by the first portion 36c, before the gluing operation. Furthermore, in this case, the first presser roller <NUM> does not perform any function of humidifying the second zone <NUM>.

It is clear that modifications and/or additions of parts may be made to the apparatus <NUM> and to the method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

For example, the sheets <NUM>, instead of being made from the strip <NUM>, could already be shaped in any known manner whatsoever, stacked in a sheet feeder and fed one at a time to the feed station <NUM>, in a manner coordinated with the movement of the forming devices <NUM> along the work path PL.

Furthermore, in accordance with other possible embodiments of the present invention, not shown in the drawings, particularly if the tubular element <NUM> is intended for the smoking articles sector, it can be provided that the forming pin <NUM> is conformed in such a way as to allow the insertion, inside its axial cavity, of a suitable filter, which will then be operatively associated with the tubular element <NUM>. The insertion of the filter in the axial cavity of the forming pin <NUM> can be provided upstream or downstream of the forming station <NUM>, in a specific filter insertion station.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of apparatuses for automatically producing tubular elements, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claim 1:
Apparatus (<NUM>) for automatically producing tubular elements (<NUM>) to make smoking articles and/or products for food use, comprising a feed unit (<NUM>) for feeding, in sequence and one at a time, a plurality of sheets (<NUM>) in a flat condition, and a forming unit (<NUM>) disposed downstream of said feed unit (<NUM>) and configured to form said tubular elements (<NUM>) starting from said sheets (<NUM>) in a flat condition, said forming unit (<NUM>) comprising one or more forming devices (<NUM>), each of which in turn comprises both a forming pin (<NUM>) rotatable around an axis of rotation (R2) thereof and having an external surface with a truncated cone or cylindrical shape, and also holding means (<NUM>, <NUM>) for temporarily holding one of said sheets (<NUM>) against said external surface; movement means (<NUM>) configured both to move said one or more forming devices (<NUM>) along a work path (PL), and also to make said forming pins (<NUM>) rotate around the respective axis of rotation (R2); and contrast means (<NUM>, <NUM>) disposed in a certain fixed position along said work path (PL) to cooperate with said sheets (<NUM>) in order to fold them in such a way that they are at least partly wound each one around a corresponding forming pin (<NUM>) in order to form one of said tubular elements (<NUM>), characterized in that said forming device (<NUM>) is configured to take said sheet (<NUM>), held by the holding means (<NUM>, <NUM>) against the external surface of the forming pin (<NUM>), against the contrast means (<NUM>, <NUM>) while the respective forming pin (<NUM>) is made to rotate, so as to cause the at least partial winding of the sheet (<NUM>) on the external surface of the forming pin (<NUM>) during the movement of the forming device (<NUM>) along the work path (PL).