The present invention relates to an apparatus for making filter rods for use in the manufacture of smoking articles such as filter cigarettes. Further, the present invention relates to a method for making a filter rod.

Filter cigarettes typically comprise a rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter aligned in end-to end relationship with the wrapped tobacco rod and attached thereto by tipping paper. The filter typically consists of one or more plugs of a fibrous filtration material. One suitable fibrous filtration material is cellulose acetate tow, that is often treated with a plasticizer like triacetin. The one or more plugs are circumscribed by a paper material typically referred to as "plug wrap".

The manufacture of filter rods from continuous fibre filter tow comprises moving the filter tow in a generally longitudinal direction through successive treatment steps for aligning tow fibres, applying plasticiser and/or other additives to the fibres before the tow is gathered, compressed and formed into a predetermined shape, such as a substantially cylindrical rod. In addition, the manufacturing process comprises wrapping the fibre tow rod with wrapping web material in order to produce a wrapped filter rod.

To this purpose, a filter rod maker includes a wrapping station for receiving the rod shaped fibre tow from a forming station and for wrapping the rod shaped fibre tow with wrapping web material to form a continuous filter rod. The wrapping station comprises an endless belt conveyor (provided, for example, as a garniture) configured to be advanced in a predetermined direction along an endless path, and a feeding device for supplying a ribbon of wrapping web material onto the belt conveyor in a first portion of the path. Further, the wrapping station comprises guide elements for gradually converting the conveyor into a tube in a second portion of the path downstream of the first path portion by moving the side edges of the belt toward each other. Filter rod makers of this type are described, for example, in US 4768526.

In more detail, the conveyor typically comprises a belt looped around two return rollers. One branch of the belt runs slidably along a longitudinal groove provided in a tongue element. The groove has a cross section that varies continuously between an inlet end and an outlet end of the tongue and which is substantially cylindrical at the outlet end. The belt sliding in the groove constitutes a garniture tape by which the wrapping web material advancing from the first path portion is guided and wrapped around the fibre tow rod in the second path portion.

The wrapping section winds the wrapping web material around the rod shaped fibre tow such that the marginal portions of the wrapping web material overlap. Further, the filter rod maker comprises a gluing station for applying a suitable adhesive to one or both side edges of the wrapping web material so that, when they overlap, they are bonded to each other. By way of example, a heat-activatable adhesive may be applied onto one or both side edges of the wrapping web material, and the filter rod maker may comprise a heat source for activating the adhesive, the heat source being arranged upstream of the garniture or at a position along the garniture. The wrapped filter rod thus produced may subsequently be cut into segments having a predetermined length to obtain filter plug elements.

While advancing through the wrapping section, the wrapping web material comes into contact with several components of the filter rod maker. The friction thus exerted on the wrapping web material may cause, in certain cases, the formation of wrapping web material filaments and dust. This may happen, in particular, with certain biodegradable plug wrap material.

This is undesirable, because wrapping web material dust and filaments that detach from the ribbon tend to accumulate in the passageways defining the path of the wrapping web material through the wrapping section. This causes an increase in the tension applied onto the ribbon, which may cause the ribbon to break. Because of this, the filter rod maker may often have to be stopped and machine downtime is therefore undesirably increased.

Therefore, it would be desirable to provide an apparatus for making filter rods for use in the manufacture of smoking articles such that the likelihood of wrapping web material dust or filaments reaching an exposed, glued surface of the filter paper ribbon is greatly limited. Further, it would be desirable to provide one such apparatus such that the amount of wrapping web material dust and filaments produced by the cooperation of the wrapping web material with the surfaces of the filter rod maker is significantly reduced.

According to an aspect of the present invention, there is provided an apparatus for making a filter rod for use in the manufacture of smoking articles. The apparatus comprises a garniture configured to receive filter plug material and wrapping web material having a first longitudinal edge and a second longitudinal edge, and to wrap the wrapping web material around the filter plug material such that the first and the second longitudinal edges overlap to form a wrapped filter rod. Further, the apparatus comprises a feeding device for supplying the wrapping web material along a web path to the garniture; and an applicator for supplying an adhesive for sealing the overlapping first and the second longitudinal edges of the wrapping web material. In addition, the apparatus comprises a web cleaning device arranged at a location along the web path upstream from the adhesive supply/applicator. The web cleaning device comprises a chamber with a web inlet and a web outlet and configured such that the wrapping web material is received into the chamber through the web inlet and leaves the chamber through the web outlet while advancing along a partially enclosed portion of the web path along a first direction (D); and a vacuum source in fluid connection with the chamber.

According to a further aspect of the present invention, there is provided a method for making a filter rod for use in the manufacture of smoking articles. The method comprises: feeding filter plug material and wrapping web material having a first longitudinal edge and a second longitudinal edge to a garniture; wrapping the wrapping web material around the filter plug material in the garniture such that the first and the second longitudinal edges overlap to form a wrapped filter rod; and supplying an adhesive to seal the overlapping first and the second longitudinal edges of the wrapping web material. Feeding the wrapping web material to the garniture comprises advancing the wrapping web material along a web path; partially enclosing a portion of the web path; and placing the thus partially enclosed portion of the web path in fluid connection with a vacuum source prior to the step of supplying an adhesive.

It shall be appreciated that any features described with reference to one aspect of the present invention are equally applicable to any other aspect of the invention.

In contrast to known apparatus, a cleaning device is provided at a location along the web path upstream from the adhesive applicator. The cleaning device comprises a chamber with a web inlet and a web outlet and configured such that the wrapping web material is received into the chamber through the web inlet and leaves the chamber through the web outlet. In practice, the chamber defines a partially enclosed portion of the web path. The wrapping web material travels through the chamber along a first direction (D). Further, the cleaning device comprises a vacuum source in fluid connection with the chamber. Thus, filter web particles and filaments that may have formed as the wrapping web material has advanced along the web path, and that are carried by the wrapping web material, can be effectively suctioned away.

By at least partially enclosing a portion of the web path and by placing the thus at least partially enclosed portion of the web path into fluid connection with a vacuum source before any glue is applied on the wrapping web material, the likelihood of filter paper dust or filaments accumulating on a glued surface of the wrapping web material is advantageously reduced.

In general terms, it is also less likely that filter paper dust and filaments may accumulate and obstruct passageways along the web path. This is advantageous because the tension applied onto the wrapping web material is maintained within an acceptable range, and so it is less likely that the wrapping web material breaks. The machine downtime can thus advantageously be reduced as a whole.

In some embodiments, by providing at least one of the several guide elements which direct the wrapping web material to travel along the web path with a cylindrical surface adapted to rotate about an axis transversal to the web path (for example, the outer surface of an idle roller), the friction exerted on the wrapping web material is significantly reduced. This is because, upon cooperation with the guide element, the filter paper ribbon drags the cylindrical surface to rotate about its axis at the at least one guide element. Accordingly, the formation of filter paper dust and particles can be advantageously limited, which further adds to the efficiency of the cleaning device and of the filter rod manufacturing process in its entirety. In the present specification, the term "partially enclosed" is used to describe a portion of the path along which the wrapping web material advances within an enclosed volume, such as a chamber internally defined by a receptacle or by a tubular element. The receptacle or tubular element has at least an opening for the filter web material to be fed into the enclosed volume and for the filter web material to travel out of the enclosed volume. Preferably, the receptacle or tubular element has both an inlet for the filter web material to enter the enclosed volume and an outlet for the filter web material to travel out of the enclosed volume. The expression "partially enclosed portion of the web path" thus identifies the portion of the enclosed volume comprised between the inlet and the outlet and within which the filter web is bound to travel.

As used herein, the terms "upper", "lower", "above", "below", "top", "bottom", "left", "right" refer to the relative positions of elements of the cleaning device of an apparatus according to the invention when the apparatus is in an upright position. In particular, these terms can be used to describe the positions of elements of the cleaning device of an apparatus according to the invention with respect to the wrapping web material advancing through the chamber of the cleaning device.

For example, in some embodiments, in the partially enclosed portion of the web path the wrapping web material travels across the chamber of the cleaning device along a substantially left-to-right or right-to-left direction. The term "substantially left-to-right or right-to-left" means that the web travels across the chamber along a direction that forms an angle aof from about 45 degrees to about 135 degrees with the vertical (see Figure 1 ). In preferred examples, the wrapping web material advances within the chamber along a substantially horizontal plane. Accordingly, the wrapping web material divides the volume of the chamber in two distinct portions, one "above" and one "below" the wrapping web material. Similarly, the plane along which the wrapping web material advances through the chamber divides the tubular element or receptacle internally defining the chamber into a "top" and a "bottom" portion arranged above and below said plane, respectively.

In other embodiments, in the partially enclosed portion of the web path the wrapping web material travels across the chamber of the cleaning device along a substantially top-to-bottom or bottom-to-top direction. The term "substantially top-to-bottom or bottom-to-top" means that the web travels across the chamber along a direction that forms an angle β greater than zero degrees and less than about 45 degrees or more than about 135 degrees and less than 180 with the vertical (see Figure 2). In preferred examples, the wrapping web material advances within the chamber along a substantially vertical plane. Accordingly, the wrapping web material divides the volume of the chamber in two distinct portions, one to the "left" and one to the "right" of the wrapping web material. Similarly, the plane along which the wrapping web material advances through the chamber divides the tubular element or receptacle internally defining the chamber into a "left" and a "right" portions arranged on the respective sides of said plane.

An apparatus according to the present invention comprises a garniture configured to receive filter plug material and wrapping web material having a first longitudinal edge and a second longitudinal edge, and to wrap the wrapping web material around the filter plug material such that the first and the second longitudinal edges overlap to form a wrapped filter rod. Further, one such apparatus comprises a feeding device for supplying the wrapping web material along a web path to the garniture, as well as an applicator for supplying an adhesive for sealing the overlapping first and the second longitudinal edges of the wrapping web material. In addition, the apparatus comprises a web cleaning device arranged at a location along the web path upstream from the adhesive supply/applicator. The web cleaning device comprises a chamber with a web inlet and a web outlet and configured such that the wrapping web material is received into the chamber through the web inlet and leaves the chamber through the web outlet while advancing along a partially enclosed portion of the web path along a first direction (D). The apparatus further comprises a vacuum source in fluid connection with the chamber.

Preferably, the cleaning device comprises a tubular body defining the chamber. An axis of the tubular body extends transversely to the first direction (D).

In particularly preferred embodiments, the axis of the tubular body is substantially perpendicular to the first direction (D). This is advantageous because the suction provided by the vacuum source draws web material particles and filaments away from the wrapping material web by which they are carried through the chamber. This minimises the likelihood that particles and filaments are accidentally picked up again by the web prior to leaving the chamber.

Preferably, the web cleaning device comprises a vacuum conduct for connecting the chamber with the vacuum source. The vacuum conduct extends from a vacuum port formed in a wall of the tubular body. An axis of the vacuum conduct extends transversely to both the first direction (D) and the axis of the tubular body.

In a preferred embodiment, the wrapping web material advances through the chamber along a substantially horizontal plane and the vacuum port is formed in a bottom portion of the wall of the tubular body. Even more preferably, the inlet and outlet are arranged in the proximity of a first end of the tubular body and the vacuum port is located in a bottom portion of the tubular body at the opposite end of the tubular body. This is advantageous in that it is less likely that web material particles and filaments suctioned away from the web may fall back onto it as they are dragged towards the vacuum port.

Preferably, the vacuum source is configured to decrease a pressure within the chamber to less than about 0.95 bar. More preferably, the vacuum source is configured to decrease a pressure within the chamber to less than about 0.90 bar. In addition, or as an alternative, the vacuum source is configured to decrease a pressure within the chamber to at least about 0.5 bar. In some preferred embodiments, the vacuum source is configured to decrease a pressure within the chamber to from about 0.5 bar to about 0.95 bar. The pressure within the chamber may be measured by means of a manometer or other pressure sensor arranged at a location proximate to the web inlet of the chamber.

Preferably, the web cleaning device further comprises a source of pressurised air selectively connectable with the chamber. By directing a flow of pressurised air onto the web, web material particles and filaments carried by the wrapping web material may be detached from it, and are thus more easily suctioned away. Thus, the overall dust removal efficiency of the cleaning device is advantageously improved. Preferably, the source of pressurised air is configured to supply a flow of air at less than about 2 bar. Higher pressure values may damage the wrapping web material and are, therefore, undesirable.

Preferably, the web cleaning device comprises at least a first air conduct for connecting the chamber with the source of pressurised air, the first air conduct extending from a first air port formed in the tubular body at a location such as to direct the flow of pressurised air against a first surface of the web advancing through the enclosed portion of the web path. This is so the flow of pressurised air may impact directly a surface of the web material, such that it is easier to dislodge web particles or filaments carried by the web, which thus can be more effectively suctioned away. For example, where the web travels across the chamber along a substantially left-to-right or right-to-left direction, the first air port may be arranged directly above or directly below the enclosed portion of the web path, such as to direct a flow of pressurised air against the upper surface or the lower surface of the web, respectively.

Preferably, the cleaning device comprises a grate support element arranged within the chamber. A first surface of the grate support element extends between an edge of the web inlet to an edge of the web outlet, both edges being on the same side of the wrapping web material advancing within the chamber. Thus, the first surface of the grate support element faces, in use, a surface of the wrapping web material.

In some preferred embodiments, the feeding device comprises one or more guide elements arranged at a location along the web path upstream from the garniture. The one or more guide elements are not motor rollers, but are intended for cooperating with, and for directing, the advancing wrapping web material along the web path. At least one of the one or more guide elements comprises an idle roller rotatable about a shaft having an axis transversal to the web path at the at least one guide element. In more detail, the one or more guide elements may comprise a substantially cylindrical tubular element that is freely rotatably mounted about a shaft, such as with bearings. The tubular element may further comprise a pair of annular stop elements projecting radially from the cylindrical outer surface of the tubular element. The annular stop elements are offset from one another by a distance that corresponds substantially to a width of the wrapping web material, such that the wrapping web material sliding against the cylindrical tubular element travels between the annular stop elements and is thus advantageously prevented from disengaging the cylindrical outer surface of the tubular element.

The friction exerted on the wrapping web material by the feeding device is thus significantly reduced. This is because, upon cooperation with the guide element, the wrapping web material may easily drag the surface of the idler roller to rotate about its shaft. By reducing the friction exerted on the wrapping web material prior to its reaching the cleaning device, the amount of web material particles and filaments formed as the wrapping web material travels in the filter rod maker can be advantageously reduced. This further enhances the overall efficiency of the cleaning device. The efficiency of the filter rod manufacturing process in its entirety is also increased, and machine downtime is also generally advantageously reduced.

An apparatus as described above may be used to implement a method for making a filter rod for use in the manufacture of smoking articles. In accordance with the present invention, one such method comprises feeding filter plug material and filter web material having a first longitudinal edge and a second longitudinal edge to a garniture; wrapping the filter web material around the filter plug material in the garniture such that the first and the second longitudinal edges overlap to form a wrapped filter rod; and supplying an adhesive to seal the overlapping first and the second longitudinal edges of the filter web material. The step of feeding the filter web material to the garniture comprises advancing the filter web material along a web path; providing a chamber to partially enclose a portion of the web path; and placing the chamber in fluid connection with a vacuum source prior to the step of supplying an adhesive.

Preferably, the method further comprises configuring the vacuum source to decrease a pressure within the chamber to from about 0.5 bar to about 0.95 bar.

Further, the method preferably comprises selectively directing a controlled flow of pressurised air into the chamber. The expression "selectively directing a controlled flow" means that a source of pressurised air may optionally be, at selected times, and for a selected amount of time, be put in fluid connection with the chamber. By varying the pressure of the source of pressurised air or by acting on suitable control means (for example, one or more valves) to adjust the flow, or both, it is possible to control the pressure and flow rate of at which air is supplied into the chamber. By way of example, a flow of pressurised air may be supplied intermittently into the chamber, during use. In addition, or as an alternative, a flow of pressurised air may be supplied into the chamber at start-up or at shut-down of the apparatus, while maintaining, at the same time, the chamber in fluid connection with the vacuum source, in order to flush possible traces of wrapping web material in the form of particles or filaments out of the chamber. In some embodiments, advancing the wrapping web material along a web path further preferably comprises guiding the wrapping web material to cooperate with one or more guide elements arranged at a location along the web path upstream from the garniture, the one or more guide elements for directing the wrapping web material along the web path; and providing at least one of the one or more guide elements with a cylindrical surface adapted to rotate, upon cooperation with the wrapping web material, about an axis transversal to an advancement direction of the wrapping web material at the at least one guide element.

The invention will be further described, by way of example only, with reference to the drawings of the accompanying Figures, wherein:

Figure 1 illustrates a schematic view of a web cleaning device in accordance with the present invention;

Figure 2 illustrates a schematic view of a variant of the web cleaning device of Figure 1 ; and

Figure 3 shows a schematic cross-sectional view of the web cleaning device of Figure 1 . Figure 1 shows a web cleaning device 100 of an apparatus 10 for making a filter rod for use in the manufacture of smoking articles. A wrapping web material 102 is supplied to the apparatus and advanced along a web path. For the sake of simplicity, other parts of the apparatus 10, such as the garniture for receiving filter plug material and wrapping web material and for wrapping the wrapping web material around the filter plug material to form a wrapped filter rod are not illustrated. The skilled person shall appreciate that a cleaning device as described below may be incorporated, for example, into an existing filter rod maker, which further comprises a feeding device for supplying the wrapping web material 102 along the web path to the garniture; and an applicator for supplying an adhesive for sealing the wrapping web material 102 around the filter plug material. The web cleaning device 100 is arranged at a location along the web path upstream from the adhesive applicator.

In the embodiment of Figure 1 , the wrapping web material travels across the web cleaning device 100 along a direction D that is substantially horizontal. The direction D forms an angle a with the vertical. The angle a is of about 90 degrees. In alternative embodiments, the wrapping web material may travel across the web cleaning device 100 along any other direction. By way of example, Figure 2 illustrates a variant of the web cleaning device of Figure 1 wherein the wrapping web material travels across a web cleaning device 1001 a direction E that is substantially vertical. The direction E forms an angle β with the vertical. The angle β is less than 45 degrees.

Figure 3 shows a sectional view of the web cleaning device 100 of Figure 1. The web cleaning device 100 comprises a chamber 104 with a web inlet 106 and a web outlet 108. The chamber 104 is configured such that the wrapping web material 102 is received into the chamber 104 through the web inlet 106 and leaves the chamber through the web outlet 108 while advancing along a partially enclosed portion of the web path along the direction D. A vacuum source (not illustrated) is in fluid connection with the chamber 104.

In more detail, the web cleaning device 100 comprises a tubular body 1 10 internally defining the chamber 104. The tubular body 1 10 extends along an axis that is substantially perpendicular to the direction D. A vacuum conduct 1 12 connects the chamber 104 with the vacuum source. The vacuum conduct 1 12 extends from a vacuum port formed in a wall of the tubular body, along an axis A that is transversal to both the direction D and the axis of the tubular body 1 10.

In the embodiment of Figure 1 , the wrapping web material 102 advances through the chamber 104 along a substantially horizontal plane, and the vacuum port is formed in a bottom portion of the wall of the tubular body 1 10. The web inlet 106 and web outlet 108 are arranged in the proximity of a first end of the tubular body 1 10, whereas the vacuum port is located in a bottom portion of the tubular body 1 10 at the opposite end of the tubular body 1 10.

In use, the vacuum source is configured to decrease a pressure within the chamber 104 to less than about 0.95 bar.

The chamber 104 may also selectively be placed in fluid connection with a source of pressurised air (not shown). A first air conduct 1 14 connects the chamber 104 with the source of pressurised air. The first air conduct 1 14 extends from a first air port 1 16 formed in the tubular body 1 10 at a location such as to direct the flow of pressurised air against the upper surface of the wrapping web material 102 advancing through the chamber 104. Further, a second air conduct 1 18 also connects the chamber 104 with the source of pressurised air, and extends from a second air port 120 formed in the tubular body at a location such as to direct the flow of pressurised air against the lower surface of the wrapping web material 102. Flow of pressurised air into the chamber 104 via the first and second air conducts 1 14, 1 18 can be selectively and independently activated.

Further, the cleaning device 100 comprises a grate support element 122 arranged within the chamber 104. A first surface of the grate support element 122 extends between an edge of the web inlet 106 to an edge of the web outlet 108, with both edges being on the same side of the wrapping web material 102 advancing within the chamber. In the embodiment of Figure 1 , the upper surface of the grate support element 122 faces, in use, the lower surface of the wrapping web material 104.

During use, filter plug material and the wrapping web material 102 are fed to a garniture, wherein the wrapping web material 102 is wrapped around the filter plug material to form a wrapped filter rod. An adhesive is supplied to seal overlapping longitudinal edges of the wrapping web material 102 so that the wrapped filter rod is sealed. In particular, the wrapping web material 102 is fed along a path which is defined by a number of elements about which the wrapping web material is guided to travel. A portion of the web path is partially enclosed by the tubular body 1 10. The partially enclosed portion of the web path is placed in fluid connection with a vacuum source prior to the step of supplying an adhesive. Thus, web material dust and filaments that may have formed and accumulated on the web can advantageously be removed prior to the web reaching the section of the apparatus wherein the adhesive is applied. In more detail, a pressure within the chamber enclosing the web path portion is decreased to a pressure of about 0.95 bar. A controlled flow of pressurised air is directed into the chamber during the start-up of the apparatus and during use such that the flow of pressurised air reaches a surface of the wrapping web material, so that the removal of dust and filaments is made easier.