Apparatus and method for automatically forming filters for smoking articles

Abstract

Apparatus (10) for automatically forming filters (100) for smoking articles starting from flat sheets (101) fed by a hopper (16) and each comprising a fan-fold part (102), formed in a first forming unit (11), and a flat part (103). The first forming unit (11) comprises at least one holding member (22) configured to hold one flat sheet (101) at a time leaving a free portion (104) on which the fan-fold part (102) is to be created freely protruding from the holding member (22), and a pair of shaping members (25, 26) having respective reciprocally offset shaping protrusions (30, 31) progressively converging to engage opposite faces of said free portion (104) in such a way as to progressively form and bring closer to each other consecutive folds with gradually greater shaping depths.

Description

[0001] APPARATUS AND METHOD FOR AUTOMATICALLY FORMING FILTERS FOR SMOKING ARTICLES

[0002] FIELD OF THE INVENTION The present invention concerns an apparatus and method for automatically forming filters for smoking articles intended to then be filled with smokable products, such as tobacco or suchlike.

[0003] BACKGROUND OF THE INVENTION

[0004] There is increasing demand to produce smoking articles comprising an external tubular casing with an elongated shape, such as cylindrical or truncated conical, which is provided at one end with a filter made of paper, or paperboard, suitably shaped and folded.

[0005] To produce this filter, apparatuses are known which fold and then roll a suitably sized flat sheet of paper, or paperboard, on itself, so that it can then be inserted into the external casing.

[0006] An apparatus is known in which the filter is made by spiraling a sheet of paperboard in two different steps, where at first one or more rotary grippers are used and then a moving plane mechanism is used. This apparatus, however, has the disadvantage of not being very versatile because, to complete the formation of the filter, the rotary grippers have to be removed, thus causing operational slowdowns.

[0007] Also known from document US 2023 / 0108165 Al is an apparatus in which a hopper contains the singularized flat sheets, and a positioning member positions them, one at a time, in a corresponding fixed pocket of a conveyor, along which the filter is then formed. In this apparatus, the flat sheet is shaped and folded in two or more shaping and folding steps, in each of which corresponding V-shaped incisions are made to form a zig-zag or fan-shaped part, around which the remaining flat, or extended, part of the flat sheet is then wrapped.

[0008] This apparatus, however, has the disadvantage of being complex and providing several shaping and folding steps, in dedicated successive stations, to create the fan-shaped part, consequently increasing the overall dimensions of the machine and production times.

[0009] Another known solution is described by US 3,818,809 A, in which male and female shaping members cooperate to shape the folds that have previously been created on the continuous paper strip by embossing rollers.

[0010] There is therefore the need to perfect an apparatus for automatically forming a filter that 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 providing an apparatus that allows to form filters for smoking articles in a simple manner, optimizing the number of operating steps to form the fan-shaped part and, therefore, reducing operating and production times.

[0011] In particular, one purpose of the present invention is to provide an apparatus and perfect a method for automatically forming filters for smoking articles that are highly efficient, versatile and that allow to achieve high productivity.

[0012] Another purpose of the present invention is to provide an apparatus and perfect a method for automatically forming filters for smoking articles that can be integrated into a more complex machine, capable of also performing other processes, for example forming external casings and / or packaging finished smoking articles.

[0013] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages. SUMMARY OF THE INVENTION

[0014] The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0015] 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 forming filters for smoking articles starting from flat sheets comprises a first forming unit configured to create a fan-fold part on a portion of each of the flat sheets, leaving a contiguous flat part unfolded. In accordance with one aspect of the present invention, the first forming unit comprises at least one holding member configured to hold one flat sheet at a time in correspondence with the flat part, leaving a free portion on which the fan-fold part is to be created freely protruding from the holding member. In accordance with one aspect of the present invention, the first forming unit comprises a pair of shaping members having shaping protrusions converging in such a way that the distance between adjacent shaping protrusions of each shaping member progressively reduces starting from a respective start shaping end to a respective finish shaping end.

[0016] The shaping protrusions of a first shaping member of the pair of shaping members are disposed offset with respect to the shaping protrusions of a second shaping member of the pair of shaping members. Moreover, the pair of shaping members, by means of the shaping protrusions, is configured to engage from opposite faces the free portion of the flat sheet held by the holding member, in such a way as to progressively form and bring closer to each other consecutive folds with gradually greater shaping depths, thus creating the fan-fold part on the free portion of the flat sheet.

[0017] In particular, one or more of the shaping protrusions have a profile with a height increasing from the respective start shaping end to the respective finish shaping end.

[0018] In accordance with another aspect of the present invention, the pair of shaping members consists of a pair of counter-rotating rollers having a respective arc shaping zone provided with the shaping protrusions. In particular, the shaping protrusions of the first shaping member are configured to be progressively inserted between the shaping protrusions of the second shaping member, and vice versa, creating folds on the free portion.

[0019] In accordance with another aspect of the present invention, the apparatus also comprises an abutment member configured to lock the position of the flat sheet with respect to the pair of shaping members by moving from a retracted position, in which it is distanced from the sheet, to an advanced position, in which it contacts the at least one holding member with the sheet positioned therebetween, during the creation of the fan-fold part.

[0020] In accordance with another aspect of the present invention, the first forming unit further comprises a first rotary device rotatable around a first main axis of rotation to move the at least one holding member along a first processing path, which runs across at least one removal station, one shaping station and one transfer station.

[0021] In accordance with another aspect of the present invention, the at least one holding member comprises one or more gripping elements configured to pick up the flat sheet from a feeding unit by contacting it on one face and leaving the opposing face free.

[0022] Doing so achieves the advantage of extracting the flat sheets directly with the holding members, without using other mechanical means that slow down operating and production times.

[0023] In accordance with another aspect of the present invention, the apparatus further comprises a collapsing device disposed downstream of the pair of shaping members and mobile between a rest position, in which it is distanced from the fan- fold part of a corresponding sheet held by the at least one holding member, and a collapsing position, in which, by means of an abutment wall, it engages and collapses the fan-fold part against a bumping wall of a bumping plate present there, so as to collapse the fan- fold part in order to stabilize the shape of the fan- fold part.

[0024] The collapsing device is also provided with a slanted surface configured and sized to slide above the bumping plate when the abutment wall is taken against the bumping wall with the fan- fold part of the sheet therebetween, in order to correctly collapse the fan-fold part.

[0025] Furthermore, a bumping plate for the flat sheet is disposed in front of the collapsing device and is provided with an abutment seating having a shape that negatively traces that of the collapsing part so as to allow the insertion of the abutment wall with minimum play and the temporary housing of the fan-fold part ready to be collapsed.

[0026] The abutment seating is provided with a bumping wall that provides an end-of- travel for the abutment wall and a rear abutment for the fan-fold part when it is collapsed by the latter.

[0027] In accordance with another aspect of the present invention, in the transfer zone there is a pusher disposed transversely with respect to the collapsing device, in order to engage the fan-fold part, which is collapsed and held by the collapsing device, in particular between the abutment wall and the bumping wall, and push the sheet with the collapsed fan-fold part toward a transfer arm configured to evacuate the sheet pushed by the pusher.

[0028] The transfer arm is configured to stably hold the flat sheet and to alternately assume a receiving position and a transfer position in which it transfers the flat sheet with the collapsed fan-fold part away from the first forming unit.

[0029] In accordance with another aspect of the present invention, the apparatus comprises a second forming unit having at least one forming mandrel provided with holding members configured to hold at least the fan-fold part and to rotate around an axis of rotation thereof, and at least one housing element disposed coaxially to the axis of rotation of the forming mandrel and provided with a hollow cylindrical body into which the holding member can be inserted, the hollow cylindrical body is provided with a lateral slit parallel to the axis of rotation and configured to allow the passage of the flat part which is rolled around the holding members when the forming mandrel rotates, so as to form the filter.

[0030] In accordance with another aspect of the present invention, the second forming unit is provided with movement means configured to move the at least one forming mandrel both around its own axis of rotation and also along a second processing path which comprises at least a forming zone and a zone for transferring the filter. The movement means comprise a second rotary device rotatable around a second main axis of rotation and on which the at least one housing element is mounted coaxially to a corresponding through hole of the rotating device, and inside which the at least one forming mandrel is positioned.

[0031] The present invention also concerns a method for automatically forming filters for smoking articles, by means of an apparatus comprising a first forming unit which performs a first forming step to form the filters starting from flat sheets in order to create a fan-fold part on a portion of each of the flat sheets, leaving a contiguous flat part unfolded.

[0032] In accordance with another aspect of the present invention, a holding member of the first forming unit holds one flat sheet at a time leaving a free portion on which the fan-fold part is to be created freely protruding from the holding member, and brings it toward a pair of shaping members of the first forming unit.

[0033] The shaping members have respective converging shaping protrusions, as defined above. The first shaping step comprises engaging, by means of the respective converging shaping protrusions, from opposite faces, the free portion of the flat sheet held by the holding member, in such a way as to progressively form and bring closer to each other consecutive folds with gradually greater shaping depths, thus creating the fan-fold part on the free portion of the flat sheet.

[0034] The shaping protrusions are reciprocally offset, curvilinear and progressively converging so that the transverse distance between each one of them is progressively reduced from respective start shaping ends to respective finish shaping ends.

[0035] In accordance with another aspect of the present invention, in the shaping step, the shaping protrusions of the first shaping member insist on one face of the free portion and are progressively inserted between the shaping protrusions of the second shaping member, which insist on the other face of the free portion, thus creating the folds.

[0036] In accordance with another aspect of the present invention, the method comprises an extraction step in which the at least one holding member, by means of respective one or more gripping elements, extracts the sheet directly from a feeding unit and holds the flat part by contacting it only on one face and leaving the opposing face free.

[0037] In accordance with another aspect of the present invention, the method comprises a collapsing step, subsequent to the shaping step, in which the sheet held by the at least one holding member is taken into a transfer station of the first forming unit with the respective fan-fold part facing toward, and aligned with, a collapsing device which, by passing from a rest position to a collapsing position, translates toward a bumping plate, and by means of an abutment wall it collapses the fan- fold part against a bumping wall of the bumping plate to stabilize the fanfold part.

[0038] In addition, during the passage from the rest position to the collapsing position, a slanted surface connected to the abutment wall slides above the bumping plate, in order to correctly perform the collapsing.

[0039] In accordance with another aspect of the present invention, the method also comprises a transfer step in which, in correspondence with the transfer zone, a pusher translates in a direction perpendicular to the collapsing device to engage the fan-fold part, collapsed and held by the collapsing device, in particular between the abutment wall and the bumping wall, and push the flat sheet with the collapsed fan-fold part toward a transfer arm, detaching the flat sheet from the at least one holding member, wherein the transfer arm stably holds the flat sheet and transfers it toward the second forming unit, passing from a receiving position to a transfer position.

[0040] In accordance with another aspect of the present invention, the method also comprises a second forming step in which, downstream of the shaping step, a respective flat sheet with the fan-fold part is received by at least one forming mandrel of a second forming unit, which holds the fan-fold part by means of holding members and cooperates with a housing element which is disposed coaxially thereto in order to form the filter, the housing element being provided with a hollow cylindrical body into which the holding member can be inserted and with a lateral slit which allows the passage of the flat part, and in which the forming mandrel rotates around an axis of rotation thereof and, by cooperating with the hollow cylindrical body, rolls the flat part around the holding members and the fan-fold part, so as to form the filter.

[0041] In accordance with another aspect of the present invention, the pair of shaping members consists of a pair of rollers which have a respective arc shaping zone provided with the shaping protrusions and which, in the shaping step, rotate in opposite directions in order to create the fan-fold part.

[0042] In accordance with some embodiments, there is provided a unit for collapsing a fan-fold part adjacent to a flat part of a sheet intended to form a filter for smoking articles, the collapsing unit comprising a collapsing device, a bumping plate and a corresponding holding member for holding the sheet, wherein the collapsing device is in accordance with the embodiments described here.

[0043] In accordance with some embodiments, there is provided an apparatus for automatically forming filters for smoking articles starting from flat sheets, comprising a shaping station in which shaping elements are present, configured to shape a free portion of the flat sheets in order to create a fan-fold part, and a station for transferring the sheets with the fan-fold part. In addition, the apparatus comprises a collapsing unit in accordance with the embodiments described here and a pusher configured to engage the fan-fold part, collapsed and held by the collapsing device, and push the sheet with the collapsed fan-fold part configured to evacuate the sheet pushed by the pusher.

[0044] DESCRIPTION OF THE DRAWINGS

[0045] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

[0046] - fig. 1 is a schematic and simplified front view of an apparatus according to the present invention for automatically forming filters for smoking articles; - fig. 2 is a schematic and simplified top view of the apparatus of fig. 1 ;

[0047] - fig. 3 is a detailed top view of a flat sheet with which to obtain a corresponding filter;

[0048] - figs, from 4 to 6 are perspective views of an operating sequence for extracting a flat sheet with which the filter is obtained; - figs, from 7 to 9 are perspective views of an operating sequence for shaping the flat sheet of fig. 3 using the shaping elements;

[0049] - figs, from 10 to 15 are detailed top views of the operating sequence for shaping the flat sheet of fig. 3 using the shaping elements;

[0050] - figs, from 10a to 15a are schematic lateral views of the operating sequence for shaping the flat sheet of fig. 3;

[0051] - figs, from 16 to 19 are perspective views of an operating sequence for transferring the flat sheet shown in fig. 3;

[0052] - figs, from 20 to 23 are partly sectioned lateral views of the operating sequence for transferring the flat sheet shown in fig. 3; - fig. 24 is an enlarged, perspective and exploded view of a detail of a second forming unit of the apparatus of fig. 1 ;

[0053] - figs. 25 and 26 are perspective views of an initial and final step of forming the filter starting from the already processed flat sheet;

[0054] - fig. 27 is a schematic front view of the second unit for forming the filter, in which a forming operating sequence is shown, the initial and final steps of which are those visible in figs. 25 and 26.

[0055] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0056] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION With reference to fig. 1, an apparatus 10 according to the present invention is suitable and usable to automatically form filters 100 for smoking articles, such as cigarettes or suchlike.

[0057] According to possible embodiments, the apparatus 10 can be part of a more complex machine, not shown in the drawings, which can comprise other apparatuses for processing the same filters 100 and / or the smoking articles’ external casings.

[0058] Before describing the apparatus 10 in detail, in order to better understand the present invention, a filter 100 is now described.

[0059] The filter 100 is obtained starting from a flat sheet 101, possibly shaped (fig. 3), made with paper having a thickness of a few tenths of a millimeter and suitably folded so as to comprise a fan-fold, or zig-zag, part 102 and a contiguous flat part 103 to be rolled around the folded part 102 (figs. 15a and from 23 to 25) to obtain the final shape of the filter 100.

[0060] The term “fan shaped” or “zig-zag” is understood as a part having a profile characterized by a succession of folds defined by a succession of ridges and grooves forming “Vs” connected to each other at the diverging ends along corresponding folding lines 105. The folding lines 105 can be pre-etched on a part of the flat sheet 101.

[0061] The term “flat sheet” is understood as an extended sheet cut to format so as to have the expected sizes and shapes. According to preferred embodiments, the flat sheet 101 can have the shape of a circular crown arc (fig. 3).

[0062] The apparatus 10 (figs. 1 and 2) comprises at least a first forming unit 11 configured to create the fan-fold part 102 on each flat sheet 101, leaving the contiguous flat part 103 unchanged. The apparatus 10 also comprises a second forming unit 12 disposed downstream of the first forming unit 11 and configured to complete the forming of the filter 100 by rolling the flat part 103 around the folded part 102.

[0063] The first forming unit 11 and the second forming unit 12 are mounted on a fixed support structure 13.

[0064] The first forming unit 11 comprises a plurality of operating zones, or stations, disposed in sequence along a first processing path PL1, including at least the following zones, schematically indicated with dashed lines in fig. 1 : - a removal station 15, in which the flat sheets 101 are fed and made available so as to be intercepted along the first processing path PL1 ;

[0065] - a shaping station 17, in which a portion of the flat sheets 101 is suitably shaped to create the folded part 102;

[0066] - a transfer or evacuation station 19, in which the folded part 102 of the sheet 101 is collapsed, and in which the sheet 101 is transferred toward the second forming unit 12.

[0067] The apparatus 10 comprises a feeding unit, or hopper, 16 (figs. 1 and from 4 to 6) inside which the flat sheets 101 are disposed stacked and in contact with each other. The first processing path PL1 is closed in a loop and forms a circumference having a first radius. It is understood that in other embodiments, not shown in the drawings, the first processing path PL1 can be rectilinear, or have at least one rectilinear segment.

[0068] The first forming unit 11 comprises a first disc-shaped rotary device 20 which is disposed parallel to the support structure 13 and which lies on a first processing plane PW1 (fig. 2). The first rotary device 20 is rotatable around a first main axis of rotation XI and, in correspondence with its periphery, it defines the first processing path PL1.

[0069] The first main axis of rotation XI is perpendicular to the support structure 13, and the first processing plane P W 1 is perpendicular to the first main axis of rotation XI . According to other embodiments, the first main axis of rotation XI is horizontal and perpendicular to the support structure 13, and the first processing plane PW1 is perpendicular to the first main axis of rotation XI.

[0070] The rotation of the first rotary device 20 occurs, for example, counterclockwise, with constant angular increments, or pitches a; this allows to perform several operations simultaneously on the flat sheets 101, consequently increasing the overall productivity of the apparatus 10. Specifically, the rotation of the first rotary device 20 is obtained by means of first drive members 21 (fig. 2) comprising, for example, one or more electronically controlled stepper motors.

[0071] In the embodiment shown in fig. 1, the angular pitch a is 90°, but it can also be different, that is, larger or smaller, depending on the choices in the design and construction of the apparatus 10. The first forming unit 11 comprises one or more holding members 22 (figs. 1, 2 and from 4 to 6) configured to cooperate with one flat sheet 101 at a time, extracting it directly from the feeding hopper 16 and holding it stably on a face, or side, along the first processing path PL1.

[0072] Preferably, the holding members 22 are disposed on the first rotary device 20 in certain radial positions and angularly offset according to the same angular intervals a.

[0073] The holding members 22 are able to cooperate with the flat part 103 of the flat sheet 101, leaving a free portion 104 protruding, to be subjected to shaping and subsequent collapsing to create the fan-fold part 102. According to possible preferred embodiments, the holding members 22 are able to rotate around an axis of rotation thereof during the rotation of the first rotary device 20, so as to correctly orient the flat sheet 101 both during transport along the first processing path PL1, and also in correspondence with the shaping 17 and transfer 19 stations. The holding members 22 are provided with one or more gripping elements 23 facing toward the exterior of the first rotary device 20 and able to hold the flat sheet 101 in correspondence with the respective flat part 103, contacting it on only one side and keeping it positioned on a positioning plane PZ. The positioning plane PZ is defined by the disposition of the gripping elements 23 and is transverse with respect to the processing plane PW 1.

[0074] Specifically, the gripping elements 23 are able to hold the flat part 103 by contacting it on one face and leaving the opposing face free.

[0075] According to possible embodiments, the gripping elements 23 are able to hold the flat sheet 101 by suction. According to other possible embodiments, the gripping elements 23 can comprise, or consist of, suckers or suchlike.

[0076] In correspondence with the shaping station 17, the first forming unit 11 comprises one or more rotary shaping elements 24 configured to perform, advantageously with a single movement, a shaping on the free portion 104, thus defining the fan-shaped profile.

[0077] The shaping elements 24 (figs. 1, 2 and from 7 to 15) comprise a pair of shaping members 25, 26, respectively a first shaping member 25 and a second shaping member 26. The shaping members 25, 26 are parallel to the first rotary device 20 and disposed on opposite sides with respect to a lying plane PG on which the flat sheet 101 lies when it is in correspondence with the shaping station 17. We must clarify that the lying plane PG is preferably perpendicular to the first processing plane PW1 and tangent to both the shaping members 25, 26 of the pair in correspondence with the shaping station 17. Furthermore, the lying plane PG and the positioning plane PZ coincide when the holding member 22 is in correspondence with the shaping station 17, with the flat sheet 101 ready to be shaped.

[0078] The shaping members 25, 26 are mounted on a support element 27 and driven by respective second drive members 28 (fig. 2).

[0079] Furthermore, the shaping members 25, 26 are provided with shaping protrusions, or ridges, 30, 31 having respective start shaping 30a, 31a and finish shaping 30b, 31b ends.

[0080] According to possible preferred embodiments, shown in the attached drawings, the shaping members 25, 26 consist of a pair of counter-rotating rollers shaped so as to each have a circular crown arc shaping zone 29, on which the shaping protrusions 30, 31 are created.

[0081] In particular, in the specific case of the shaping members 25, 26, these are able to rotate in opposite directions around respective secondary axes of rotation X3, X4 parallel to each other, in order to progressively pass from a stop condition Cl to a shaping condition C2 (figs, from 7 to 15), and vice versa, as will be described in detail below. The secondary axes of rotation X3, X4 are parallel to the first main axis of rotation XI .

[0082] The shaping protrusions 30, 31 of the shaping members 25, 26 are reciprocally offset; specifically, the shaping protrusions 30 of a first shaping member 25 of the pair of shaping members 25, 26 are disposed offset with respect to the shaping protrusions 31 of a second shaping member 26 of the pair of shaping members 25, 26. In particular, during the passage from the stop condition Cl to the shaping condition C2 (figs, from 7 to 15), the shaping protrusions 30 of the first shaping member 25 are able to be progressively inserted between the shaping protrusions 31 of the second shaping member 26, and vice versa, contacting from opposite sides the free portion 104 of the flat sheet 101 which lies on the lying plane PG, and thus defining a succession of V-shaped folds able to form the folded part 102 (figs, from 10a to 15a).

[0083] According to possible embodiments, the shaping protrusions 30, 31 (figs, from 7 to 15) are curvilinear and progressively converging.

[0084] The shaping protrusions 30, 31 (figs, from 7 to 15) are respectively converging in such a way that the transverse distance between adjacent shaping protrusions

[0085] 30, 31 of each shaping member 25, 26 progressively reduces starting from the start shaping ends 30a, 31a to the finish shaping ends 30b, 31b. According to some embodiments, the shaping protrusions 30, 31 have varying radii of curvature.

[0086] Furthermore, one or more of the shaping protrusions 30, 31 are created in such a way that the profile has a height that increases from the start shaping ends 30a, 3 la to the finish shaping ends 30b, 31b.

[0087] Advantageously, the progressive convergence and the progressive increase in height of the shaping protrusions 30, 31 allows to perform a shaping capable of both compensating for the curvature of the free portion 104, so that the folding lines 105 of the folded part 102 are substantially parallel to each other, and also of progressively forming the V-shaped folds in height, taking into account that the convergence causes the V-shaped folds to move progressively closer to each other.

[0088] Therefore, the shaping members 25, 26, by means of the shaping protrusions 30,

[0089] 31, are able to engage the free portion 104 from opposite faces, or parts, and in a progressive manner with gradually greater convergences and shaping depths so that, during the passage from the stop condition Cl to the shaping condition C2, corresponding V-shaped folds are progressively formed and brought closer to each other, thus creating, at least temporarily, the folded part 102.

[0090] In this case, the shaping protrusions 30 (figs, from 10 to 15) of the first shaping member 25 are defined by a first external protrusion 32a, disposed on the opposite side with respect to the holding member 22, a first internal protrusion 32b, facing the holding member 22, and at least one intermediate protrusion 32c interposed between the first external 32a and internal 32b protrusion. The first external protrusion 32a has a substantially constant height, while the internal 32b and intermediate 32c protrusion have a profile with an increasing height, as indicated above. The first external protrusion 32a has a greater length than the internal 32b and intermediate 32c protrusion; while the first internal protrusion 32b has a greater length than the intermediate protrusion 32c.

[0091] The shaping protrusions 31 of the second shaping member 26 are defined by at least a second external protrusion 33a, disposed on the opposite side with respect to the holding member 22, and an internal protrusion 33b facing the holding member 22. The second external 33a and internal 33b protrusion have a profile with a substantially constant height and a substantially equal length.

[0092] As can be seen in fig. 10, the first external protrusion 32a, being more convergent, has a greater curvature than the intermediate protrusion 32c and the latter has a slightly greater curvature than the internal protrusion 32b. In the same manner, the second external protrusion 33a, being slightly more convergent, has a slightly greater curvature than the second internal protrusion 33b.

[0093] The first external protrusion 32a (figs, from 10 to 15) has the function of engaging the terminal zone of the free portion 104, folding it toward the second external protrusion 33a, while the intermediate protrusion 32c and the first internal protrusion 32b have the function of cooperating with the second external 33a and internal 33b protrusion to progressively form the V-shaped folds in height, gradually bringing them closer to each other thanks to the respective curvatures. In addition, the first external protrusion 32a, with a terminal part thereof that extends beyond the internal 32b and intermediate 32c protrusion, has the function of collapsing the V-shaped folds thus formed one on top of the other, creating, at least temporarily, the fan-fold part 102.

[0094] We must clarify that the term “at least temporarily” refers to the fact that the folded part 102 tends to once again expand elastically, once the shaping operation is completed, due to the inherent properties of the material (paper) with which the filters 100 are made. According to other possible embodiments, not shown in the drawings, the first shaping member 25 can be provided with two or more intermediate protrusions 32c and the second shaping member 26 can also be provided with respective intermediate protrusions in relation to the number of V-shaped folds to be created on the free portion 104.

[0095] In correspondence with the shaping station 17 there is also an abutment member 35 (figs. 1, 2 and from 7 to 15) configured to adjust the position of the flat sheet

[0096] 101 with respect to the pair of shaping members 25, 26 by moving from a retracted position P 1 , in which it is distanced from the flat sheet 101 , to an advanced position

[0097] P2, in which it contacts it on the opposite side with respect to the holding member 22, during the creation of the folded part 102.

[0098] In particular, the abutment member 35 is disposed close to the first rotary device 20 and is provided with a respective bumping wall 36, facing the latter, which in the advanced position P2 is able to contact the flat part 103 of the flat sheet 101 on the opposite side with respect to the holding member 22 that holds it.

[0099] Advantageously, the bumping wall 36 can have an external layer of substantially soft, or flexible, material with a high friction coefficient, so as to prevent a possible relative movement of the flat sheet 101 during the shaping operation, or step. For example, the external layer can be made of rubber.

[0100] A third drive member 37 (figs, from 7 to 9) is provided to drive the abutment member 35, to take it from the retracted position Pl to the advanced position P2, and vice versa.

[0101] The first forming unit 11 comprises, in correspondence with the transfer zone 19, a collapsing device 39 (figs. 1, 2 and from 16 to 23) adjacent to the first rotary device 20 and mobile between a rest position PP, in which it is distanced from the folded part 102, and a collapsing position PS to engage and collapse the folded part

[0102] 102 which has partly expanded elastically, engaging and collapsing it toward the flat part 103 which is held by the corresponding holding member 22, thus again obtaining a correct fan-fold part 102.

[0103] Specifically, the collapsing device 39 is provided with at least a lower collapsing part 40, having an abutment step, or wall, 41 able to engage the outermost fold of the folded part 102. Furthermore, the collapsing device 39 is also provided with an upper coupling part 42, protruding with respect to the abutment wall 41. The coupling part 42 has a recess 43 mating in shape with the holding members 22.

[0104] The coupling part 42 is conformed in such a way as to have a lower slanted surface 44 which connects with the abutment wall 41 and is configured and sized to be disposed above the bumping plate 46, when the abutment wall 41 is taken against the bumping wall 48 with the folded part 102 interposed. In particular, the slanted surface 44, when the collapsing device 39 passes from the rest position PP to the collapsing position PS, has the function of contacting during use the folded part 102 to direct it correctly toward the abutment wall 41, to perform the collapsing correctly.

[0105] A bumping plate 46 (figs. 1, 2 and from 16 to 23) is disposed in front of the collapsing device 39 and below the first rotary device 20 to provide an abutment and support to the sheet 101 during the collapsing of the folded part 102. The bumping plate 46 is provided with an abutment seating 47 having a shape that negatively traces that of the collapsing part 40, so as to allow the insertion of the abutment wall 41 with minimum play and the temporary housing of the folded part 102 ready to be collapsed.

[0106] Furthermore, the abutment seating 47 is provided with a bumping wall 48 that provides an end-of- travel for the abutment wall 41 and a rear abutment for the folded part 102 when it is collapsed by the latter.

[0107] In other words, the collapsing device 39 (figs, from 16 to 23) is able to translate toward the bumping plate 46 in a direction perpendicular thereto, passing from the rest position PP, in which it is aligned and distanced from the holding member 22 and from the bumping plate 46, to the collapsing position PS, in which, by cooperating with the holding member 22 it is able, with the respective abutment wall 41, to engage and collapse the folded part 102 against the bumping wall 48.

[0108] We must highlight that the coupling between the holding member 22 and the recess 43 allows to stably guide the translation of the collapsing device 39. A fourth drive member 49 (fig. 1) is provided to drive the collapsing device 39, in order to bring it from the rest position PP to the collapsing position PS, and vice versa.

[0109] We must clarify that the collapsing device 39, the bumping plate 46 and a corresponding holding member 22 of the sheet 101 together define a unit for collapsing the fan-fold part 102.

[0110] In correspondence with the transfer zone 19 there is also a pusher 50 disposed transversely with respect to the collapsing device 39 and able to translate perpendicularly thereto in order to engage the folded part 102, which is collapsed between the abutment wall 41 and the bumping wall 48, and push it toward a transfer arm 51 disposed between the first and second forming units 11, 12, evacuating the sheet 101.

[0111] We must clarify that the pushing force generated by the pusher 50 is such as to allow the detachment of the sheet 101 from the holding member 22. Preferably, the transfer of the sheet 101 can occur by means of a horizontal translational movement.

[0112] The pusher 50 is able to translate along an evacuation guide 54 of the folded part 102 present in the bumping plate 46. The evacuation guide 54 is made so as to perpendicularly intercept the abutment seating 47 in correspondence with a terminal part thereof, that is, in correspondence with the bumping wall 48.

[0113] The transfer arm 51 (figs, from 16 to 19) is arranged in a receiving position PR to receive the sheet 101 pushed by the pusher 50, and to transfer it to the second forming unit 12, passing from the receiving position PR to a transfer position PT. The passage from the receiving position PR to the transfer position PT (fig. 24) can preferably occur by means of a horizontal rotary movement of the transfer arm 51 which is actuated, or moved, by means of a fifth drive member 52.

[0114] The transfer arm 51 is provided with a housing seating 53 in which the folded part 102 of the sheet 101 can be housed, and with holding elements 55 to stably hold the flat part 103.

[0115] For example, as shown in fig. 14, the holding elements 55 can comprise a plate attached to the transfer arm 51 , the surface of which can be at least partly coated with a high adhesion material, for example an elastomeric material. This plate is disposed so as to leave a gap between it and the transfer arm 51 below, the gap being configured to receive the flat part 103.

[0116] We must clarify that, in addition to the transfer arm 51, another pusher member can also be present, not shown in the drawings, which allows to correctly conclude the transfer of the already processed sheet 101 toward the second forming unit 12.

[0117] The second forming unit 12 (figs. 1 and 2) comprises a plurality of operating zones, or stations, disposed in sequence along a second processing path PL2, including at least the following zones, schematically indicated with dashed lines in fig. 1 :

[0118] - a receiving zone 60, in which the already processed sheets 101 are transferred one at a time by means of the transfer arm 51 until they intercept the second processing path PL2;

[0119] - a forming zone 61, in which the forming of a filter 100 starting from the corresponding sheet 101 is completed, as indicated above; - a transfer zone 62, in which one filter 100 at a time is transferred toward another processing zone.

[0120] Preferably, the second processing path PL2 is closed in a loop and forms a circumference having a second radius. It is understood that in other embodiments, not shown in the drawings, the second processing path PL2 can be rectilinear, or have at least one rectilinear segment.

[0121] The second forming unit 12 comprises movement means 63 which are configured to move respective forming mandrels 66 for forming the filters 100 at least along the processing path PL2, as will be described in detail below.

[0122] The movement means 66 comprise a second disc-shaped rotary device 65 which is disposed parallel to the support structure 13 and which lies on a second processing plane PW2. The second rotary device 65 is rotatable around a second main axis of rotation X2, parallel to the first main axis of rotation XI, and, in correspondence with its periphery, it defines the second processing path PL2. According to possible embodiments, the second main axis of rotation X2 is horizontal and perpendicular to the support structure 13, and the second processing plane PW2 is vertical and perpendicular to the second main axis of rotation X2.

[0123] Therefore, the first and second processing plane PW1 and PW2 are parallel to each other and distanced so as not to interfere with each other.

[0124] The rotation of the second rotary device 65 can occur both clockwise as well as counterclockwise, with constant angular increments, or pitches, p; this allows to perform several operations simultaneously on the sheets 101, consequently increasing the overall productivity of the apparatus 10. Specifically, the rotation of the second rotary device 65 is obtained by means of sixth drive members 67 (fig. 2) comprising, for example, one or more electronically controlled stepper motors. In the embodiment shown in fig. 1, the angular pitch p is 45°, but it can also be different, that is, larger or smaller, depending on the choices in the design and construction of the apparatus 10.

[0125] The second rotary device 65 is provided with a plurality of through holes 69 (fig. 14) made in determinate radial positions and angularly offset according to the same angular intervals [3.

[0126] The second forming unit 12 comprises the forming mandrels 66 (figs. 1, 2 and from 24 to 27) rotatable around an axis of rotation X5 thereof to form the filter 100, and housing elements 70 disposed coaxially to the axis of rotation X5 in a fixed axial position with respect to the forming mandrels 66. We must clarify that each axis of rotation X5 is parallel to the second main axis of rotation X2.

[0127] According to preferred embodiments, the housing elements 70 are mounted on the second rotary device 65 coaxially to the through holes 69, and the forming mandrels 66 are each positioned inside a respective through hole 69 so that at least a part thereof protrudes from the latter in order to cooperate with a corresponding housing element 70, as will be described in detail below.

[0128] In the examples given here, the through holes 69, the forming mandrels 69 and the housing elements 70 are eight (fig. 1), since the angular intervals [3 are of 45°; it is clear that in other embodiments they can be in a number greater or lower than eight, chosen in any case depending on the number of angular intervals [3.

[0129] According to the embodiments shown in fig. 14, each housing element 70 has a substantially tubular shape and comprises both a hollow cylindrical body 71 made through, coaxial to the axis of rotation X5, and in which at least the fan-fold part 102 of the sheet 101 can be inserted, and also at least one lateral slit 72, tangent to the hollow cylindrical body 71 and having the function of allowing the passage of the flat part 103 of the same sheet 101.

[0130] According to other embodiments, not shown in the drawings, the housing elements 70 can be different from those described and / or shown here; for example, they can be formed by two substantially semi-cylindrical portions and conformed in such a way as to allow the housing of the sheet 101.

[0131] The forming mandrels 66 each comprise an oblong body provided, in correspondence with one end thereof, with a holding member 75 for holding the folded part 102. As can be observed in figs. 1 and from 24 to 27, along the second processing path PL2 each forming mandrel 66 is disposed in an operating position in which the respective holding members 75 are disposed inside the hollow cylindrical body 71. The holding members 75 comprise, or consist of, at least two gripping elements 76, for example jaws, which oppose each other with respect to the axis of rotation X5 and are configured to hold the folded part 102 inside the hollow cylindrical body 71 (figs, from 24 to 27). According to preferred embodiments, the two gripping elements 76 are fixed and distanced by a certain distance, such that they hold the folded part 102 by interference.

[0132] According to other embodiments, not shown in the drawings, the gripping elements 76 can be able to open and close selectively in order to hold and, respectively, release the sheet 101. Moreover, it is clear that according to other embodiments, other holding members 75 suitable to hold the sheet 101 can be used.

[0133] The forming mandrels 66 are able to rotate independently around their axis of rotation X5 with respect to the rotation of the second rotary device 65. For example, during a single angular pitch 0 each forming mandrel 66 is able to perform one or more 360° rotations around its axis of rotation X5, in order to roll the flat part 103 around the folded part 102 held by the holding members 75, thus forming a filter 100.

[0134] We must clarify that the movement means 63 are configured to also be able to selectively move each forming mandrel 66 around and along its own axis of rotation X5; for example, the movement means 63 can also 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 mandrel 66.

[0135] In correspondence with the transfer zone 62, it can be the same forming mandrels 66 that allow each filter 100 to be transferred to another apparatus, zone, or processing device, for example by sliding or translating axially to another operating position. Alternatively, there can be other suitable transfer means of a known type and not shown in the drawings.

[0136] The apparatus 10 comprises a central control unit 77 (fig. 2) programmed to control and command the activation of the drive members 21, 28, 37, 49, 52 and 67 and the movement means 63, so as to synchronize the rotations of the rotary devices 20 and 65 and the shaping elements 24, as well as the movements of the abutment member 35, the compression device 39, the pusher 50, the transfer arm 51 and the forming mandrels 66. The operation of the apparatus 10 described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

[0137] We must clarify that what described for a single sheet 101 will be cyclically valid for each of the sheets 101 with which the filters 100 are obtained. In an initial preparation step, the central control unit 77 is programmed to control and coordinate the drive of the rotary devices 20 and 65, the shaping elements 24, the abutment member 35, the compression device 39, the pusher 50, the transfer arm 51 and the forming mandrels 66.

[0138] In a feeding step (fig. 4), the flat sheets 101 are fed toward the removal station 15 by means of the feeding hopper 16, so that they are positioned along the first processing path PL1.

[0139] In correspondence with the first forming unit 11 , a first step of forming the filters 100 starting from corresponding flat sheets 101 is carried out. The first forming step comprises at least an extraction step, a shaping step and a folding step of the flat sheets 101.

[0140] In the extraction step (figs. 5 and 6), by means of the rotation of the first rotary device 20, a respective holding member 22 intercepts and engages a corresponding flat sheet 101, extracting it directly from the feeding hopper 16 and holding it on one side only. Specifically, the holding member 22, by means of its gripping elements 23, holds the flat sheet 101 in correspondence with its flat part 103, contacting it on one face only, leaving the opposing face free and making the free portion 104 protrude.

[0141] Then, by means of the rotation of the rotary device 20, the flat sheet 101 is transported toward the shaping station 17. In the shaping step (fig. 7), in correspondence with the shaping station 17, the flat sheet 101 is positioned so as to be aligned and coplanar with the lying plane PG, and the abutment member 35 passes from the retracted position Pl to the advanced position P2 in order to contact the flat sheet 101 with the respective bumping wall 36, stabilizing its position. That abutment member 35 contacts the flat sheet 101 from the opposite side with respect to the holding member 22.

[0142] Then the shaping elements 24 for shaping the free portion 104 (figs, from 8 to 15) are driven. Specifically, during shaping, the shaping protrusions 30 of the first shaping member 25 insist on one face of the free portion 104 and are progressively inserted between the shaping protrusions 31 of the second shaping member 26, which insist on the other face of the free portion 104, thus creating the folds.

[0143] In particular, the shaping protrusions 30, 31 engage on opposite faces of the free portion 104 in a progressive manner with gradually greater convergences and shaping depths so that corresponding V-shaped folds are progressively formed and brought closer to each other, thus creating, at least temporarily, the folded part 102.

[0144] In preferred embodiments, the shaping members 25, 26 are rollers and rotate in opposing directions to pass from the stop condition C 1 to the shaping condition C2 and create the folded part 102 with the respective shaping protrusions 30, 31. In this specific case, during the passage from the stop condition Cl to the shaping condition C2, the first external protrusion 32a engages the terminal zone of the free portion 104, folding it toward the second external protrusion 33a, while the intermediate protrusion 32c and the first internal protrusion 32b cooperate with the second external 33a and internal 33b protrusion to progressively form the V- shaped folds, gradually bringing them closer to each other thanks to the respective curvatures. In addition, the first external protrusion 32a, with a terminal part thereof, collapses the V-shaped folds thus formed one on top of the other, creating, at least temporarily, the fan-fold part 102.

[0145] Once the shaping has ended, the shaping members 25, 26 rotate in reciprocally opposite directions to return to the stop condition Cl .

[0146] Then, by means of the rotation of the rotary device 20, the sheet 101 is transported toward the transfer station 19.

[0147] In the collapsing step (fig. 16), the sheet 101 is disposed so as to have the folded part 102, partly elastically expanded, facing and aligned with the collapsing device 39.

[0148] In this step (figs. 17, 18 and from 20 to 23), the collapsing device 39, by passing from the rest position PP to the collapsing position PS, translates toward the bumping plate 46 in a direction perpendicular thereto, and with the abutment wall 41 it collapses the folded part 102 against the bumping wall 48, thus once again obtaining a correct fan-fold part 102. During the passage from the rest position PP to the collapsing position PS, at least a portion of the holding member 22 is inserted into the recess 43 of the collapsing device 39, stably guiding the movement of the latter, and the lower slanted surface 44 correctly directs the folded part 102 toward the abutment wall 41, moving above the bumping plate 46, thus correctly performing the collapsing.

[0149] Subsequently, in a transfer station (fig. 19), the pusher 50 translates along the evacuation guide 54 in a direction perpendicular to the collapsing device 39 in order to engage the folded part 102 collapsed between the abutment wall 41 and the bumping wall 48 and push it toward the transfer arm 51 present there, thus detaching the sheet 101 from the holding member 22.

[0150] Then, once this operation has ended, the collapsing device 39 returns to the rest position PP and the pusher 50 to the starting position. We must highlight that the transfer arm 51 is arranged in a receiving position PR to receive, in a housing seating 53 thereof, the folded part 102 of the sheet 101 moved by the pusher 50, stably holding the flat part 103 with respective holding elements 55 (fig. 19). Please note that in the receiving position PR, the housing seating 53 is aligned with the evacuation guide 54. Subsequently, the transfer arm 51 passes from the receiving position PR to the transfer position PT to transfer the sheet 101 toward the second forming unit 12.

[0151] In correspondence with the second forming unit 11 , a second step of forming the filters 100 starting from the corresponding, already processed, flat sheets 101 is carried out. The second forming step comprises a receiving step (fig. 24), in which the sheet 101 is received in correspondence with the receiving zone 60 of the second forming unit 12. In particular, by means of the transfer arm 51 and possibly a pusher member, the sheet 101 is inserted head-wise, that is, from the front, into the hollow cylindrical body 71 of a housing element 70 of the second rotary device 65, so that the folded part 102 of the sheet 101 slots in and is held, at least by interference, between the gripping elements 76 of the holding members 75 of the forming mandrel 66, and so that the flat part 103 is positioned in the corresponding lateral slit 72.

[0152] Then, in the second forming step (figs, from 25 to 27), while the second rotary device 65 rotates around its second main axis of rotation X2, the forming mandrel 66 rotates around its axis of rotation X5 according to a certain direction of rotation, and by cooperating with the corresponding housing element 70, in particular with the hollow cylindrical body 71, it rolls the flat part 103 of the sheet 101 around the folded part 102 and the gripping elements 76, thus forming the filter 100.

[0153] Once the filter 100 has been formed, another transfer step is carried out in correspondence with the transfer zone 62, in which the filter 100 is transferred toward another apparatus, zone, or processing device.

[0154] According to some embodiments, this transfer can be achieved by means of the same forming mandrel 66 which, by passing to another operating position, transfers the corresponding filter 100 to another apparatus, zone, or processing device. Alternatively, this transfer can be achieved by means of other suitable transfer means, of a known type and not shown in the drawings.

[0155] It is clear that modifications and / or additions of parts or steps may be made to the apparatus 10 and to the method as described heretofore, without thereby departing from the field and scope of the present invention, as defined by the claims. 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 will be able to achieve other equivalent forms of apparatuses and methods for automatically forming filters for smoking articles, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors of the field of protection.

Claims

CLAIMS1. Apparatus (10) for automatically forming filters (100) for smoking articles starting from flat sheets (101), said apparatus (10) comprising a first forming unit (11) configured to create a fan- fold part (102) on a portion of each of said flat sheets (101), leaving a contiguous flat part (103) unfolded, said first forming unit(11) comprising at least one holding member (22) configured to hold one flat sheet (101) at a time leaving a free portion (104) on which said fan- fold part (102) is to be created freely protruding from the holding member (22), characterized in that said first forming unit (11) further comprises a pair of shaping members (25, 26) having respective shaping protrusions (30, 31) converging in such a way that the distance between adjacent shaping protrusions (30, 31) of each shaping member (25, 26) progressively reduces starting from a respective start shaping end (30a, 3 la) to a respective finish shaping end (30b, 31b), wherein the shaping protrusions (30) of a first shaping member (25) of said pair of shaping members (25, 26) are disposed offset with respect to the shaping protrusions (31) of a second shaping member (26) of said pair of shaping members (25, 26), said pair of shaping members (25, 26), by means of said shaping protrusions (30, 31), being configured to engage opposite faces of said free portion (104) of said flat sheet (101) held by said holding member (22), in such a way as to progressively form and bring closer to each other consecutive folds with gradually greater shaping depths, thus creating said fan-fold part (102) on said free portion (104) of said flat sheet (101).

2. Apparatus (10) as in claim 1, characterized in that one or more of said shaping protrusions (30, 31) have a profile with a height increasing from the respective start shaping end (30a, 31a) to the respective finish shaping end (30b, 31b).

3. Apparatus (10) as in claim 1 or 2, characterized in that said pair of shaping members (25, 26) consists of a pair of counter-rotating rollers having a respective arc shaping zone (29) provided with said shaping protrusions (30, 31) thereon, and in that the shaping protrusions (30, 31) of said first (25) and second (26) shaping members (25) are configured to be progressively inserted between one another, creating folds on said free portion (104).

4. Apparatus (10) as in any claim hereinbefore, characterized in that it also comprises an abutment member (35) configured to lock the position of said flat sheet (101) with respect to said pair of shaping members (25, 26) by moving froma retracted position (Pl), in which it is distanced from the sheet (101), to an advanced position (P2), in which it contacts said at least one holding member (22) with the sheet (101) positioned therebetween, during the creation of said fan-fold part (102).

5. Apparatus (10) as in any claim hereinbefore, characterized in that said first forming unit (11) further comprises a first rotary device (20) rotatable around a first main axis of rotation (XI) to move said at least one holding member (22) along a first processing path (PL1) which runs across at least one removal station (15), one shaping station (17) and one transfer station (19).

6. Apparatus (10) as in any claim hereinbefore, characterized in that said at least one holding member (22) comprises one or more gripping elements (23) configured to pick up said flat sheet (101) from a feeding unit (16) by contacting it on one face and leaving the opposing face free.

7. Apparatus (10) as in any claim hereinbefore, characterized by further comprising a collapsing device (39) disposed downstream of said pair of shaping members (25, 26) and mobile between a rest position (PP), in which it is distanced from the fan-fold part (102) of a corresponding sheet (101) held by said at least one holding member (22), and a collapsing position (PS), in which, by means of an abutment wall (41), it engages and collapses said fan-fold part (102) against a bumping wall (48) of a bumping plate (46), in such a way as to collapse said fanfold part (102), to stabilize the shape of said fan-fold part (102).

8. Apparatus (10) as in claim 7, characterized in that said collapsing device (39) is provided with a slanted surface (44) which is configured and sized to slide above the bumping plate (46), when said abutment wall (41) is taken against said bumping wall (48) with said fan-fold part (102) of the sheet therebetween, to correctly collapse the fan-fold part (102).

9. Apparatus (10) as in any claim hereinbefore, characterized by further comprising a second forming unit (12) having at least one forming mandrel (66) provided with a holding member (75) configured to hold said fan-fold part (102) and to rotate around an axis of rotation (X5), and at least one housing element (70) disposed coaxially to said axis of rotation (X5) of the forming mandrel (66) and provided with a hollow cylindrical body (71), into which said holding member (75) can be inserted, said hollow cylindrical body (71) being provided with a lateral slit(72) parallel to said axis of rotation (X5) and configured to allow the passage of the flat part (103) which is rolled around said holding member (75) when said forming mandrel (66) rotates, so as to form said filter (100).

10. Method for automatically forming filters (100) for smoking articles, by means of an apparatus (10) comprising a first forming unit (11) which performs a first forming step to form said filters (100) starting from flat sheets (101) in order to create a fan-fold part (102) on a portion of each of said flat sheets (101), leaving a contiguous flat part (103) unfolded, wherein a holding member (22) of said first forming unit (11) holds one flat sheet (101) at a time leaving a free portion (104) on which said fan- fold part (102) is to be created freely protruding from the holding member (22), and brings it toward a pair of shaping members (25, 26) of said first forming unit (11), characterized in that said shaping members (25, 26) have respective converging shaping protrusions (30, 31), wherein the distance between adjacent shaping protrusions (30, 31) of each shaping member (25, 26) progressively reduces starting from a respective start shaping end (30a, 31a) to a respective finish shaping end (30b, 31b), the shaping protrusions (30) of a first shaping member (25) of said pair of shaping members (25, 26) being disposed offset with respect to the shaping protrusions (31) of a second shaping member (26) of said pair of shaping members (25, 26), said first shaping step also comprising engaging by means of said respective converging shaping protrusions (30, 31), from opposite faces, said free portion (104) of said flat sheet (101) held by said holding member (22), in such a way as to progressively form and bring closer to each other consecutive folds with gradually greater shaping depths, thus creating said fan-fold part (102) on said free portion (104) of said flat sheet (101).

11. Method as in claim 10, characterized in that in said shaping step, the shaping protrusions (30) of said first shaping member (25) insist on one face of said free portion (104) and are progressively inserted between the shaping protrusions (31) of said second shaping member (26), which insist on the other face of said free portion (104), thus creating said folds.

12. Method as in claim 10 or 11 , characterized in that it comprises an extraction step in which said at least one holding member (22), by means of respective one or more gripping elements (23), extracts said sheet (101) directly from a feeding unit (16) and holds said flat part (103) by contacting it only on one face and leavingthe opposing face free.

13. Method as in claim 10, 11 or 12, characterized in that it comprises a collapsing step, subsequent to said shaping step, in which said sheet (101) held by said at least one holding member (22) is taken into a transfer station (19) of said first forming unit (11) with the respective fan-fold part (102) facing toward, and aligned with, a collapsing device (39), which, by passing from a rest position (PP) to a collapsing position (PS), translates toward a bumping plate (46), and by means of an abutment wall (41), it collapses said fan-fold part (102) against a bumping wall (48) of said bumping plate (46) to stabilize said fan- fold part (102).

14. Method as in claim 13, characterized in that, during the passage from said rest position (PP) to said collapsing position (PS), a slanted surface (44) connected to said abutment wall (41) slides above the bumping plate (46), in order to correctly perform said collapsing.

15. Method as in any claim from 10 to 14, characterized in that it also comprises a second forming step in which, downstream of the shaping step, a respective sheet with said fan-fold part (102) is received by a forming mandrel (66) of a second forming unit (12), which holds said fan-fold part (102) by means of a holding member (75) and cooperates with a housing element (70) which is disposed coaxially thereto in order to form said filter (100), said housing element (70) being provided with a hollow cylindrical body (71), into which said holding member (75) can be inserted and with a lateral slit (72) which allows the passage of the flat part (103), and in which said forming mandrel (66) rotates around an axis of rotation (X5) thereof and, by cooperating with the cylindrical body (71), rolls said flat part (103) around said holding member (75) and said fan-fold part (102), so as to form said filter (100).

16. Method as in any claim from 10 to 15, characterized in that said pair of shaping members (25, 26) consists of a pair of rollers which have a respective arc shaping zone (29) provided with said shaping protrusions (30, 31) and which, in said shaping step, rotate in opposite directions in order to create said fan-fold part (102).

17. Collapsing unit for collapsing a fan-fold part (102) adjacent to a flat part (103) of a sheet (101) intended to form a filter (100) for smoking articles, said collapsing unit comprising a collapsing device (39), a bumping plate (46) and aholding member (22) for holding said sheet (101), characterized in that said collapsing device (39) is configured to translate from a rest position (PP) in which it is distanced from the fan-fold part (102) to a collapsing position (PS) in which, by means of an abutment wall (41), it engages and collapses said fan- fold part (102) against a bumping wall (48) of said bumping plate (46), in such a way as to collapse said fan-fold part (102), to stabilize the shape of said fan-fold part (102).

18. Unit as in claim 17, characterized in that said collapsing device (39) is also provided with a slanted surface (44) configured and sized to slide above the bumping plate (46), when said abutment wall (41) is taken against said bumping wall (48) with said fan- fold part (102) therebetween.

19. Apparatus (10) for automatically forming filters (100) for smoking articles starting from flat sheets (101), characterized by comprising a shaping station (17) which comprises shaping elements (24) configured to shape a free portion (104) of said flat sheets (101) to create a fan-fold part (102), and a transfer station (19) for transferring said sheets (101) with said fan-fold part (102), said apparatus (10) further comprising a collapsing unit as in claim 17 or 18 and a pusher (50) configured to engage said fan-fold part (102), collapsed and held by said collapsing device (39), and push the sheet (101) with the collapsed fan-fold part (102) compressed toward a transfer arm (51), configured to evacuate the sheet (101) pushed by the pusher (50).

Images