Methods and Apparatuses for Manufacture of Smoking Article Filters

The present invention relates to a method and apparatus for producing filters and filter rods for use in the manufacture of smoking articles.

Filter materials are formed into rods during manufacture and such rods may be cut into smaller units for the application of filter tips to smoking articles. Existing methods and apparatuses of producing filter rods can produce filter rods with relief patterns, such as grooves, on their outer surface and include forming a filter rod and subsequently forming a pattern/grooves into the outer surface of the filter rod using a post-processing technique. An alternative existing method of forming filter rods with a relief pattern in their outer surface includes creating the desired pattern in a plug wrap and then wrapping the filter material in the shaped plug wrap so that the filter material conforms to the applied shape of the outer plug wrap. In all cases, the filter rods are formed using existing an method and apparatus, and the patterned shape for the filter is performed in a separate earlier or later step.

In accordance with various embodiments of the invention, there is provided an apparatus for manufacturing a filter rod for a cigarette or other smoking article having a pattern formed in relief on the outer surface thereof, the apparatus comprising, a passage including a portion configured to receive and compress filter material to form a filter rod and a belt extending along the passage to convey filter material through the passage, wherein the apparatus includes a patterned relief surface configured to impress the relief pattern on a surface of a filter rod as it is formed within the passage.

The relief surface may be formed on the belt such that the belt engages the filter material and impresses the relief pattern on the surface of the filter rod as it passes through the passage. The belt may comprise a plurality of plates hingedly coupled end-to-end, and at least one of the plates may be metallic. Furthermore, at least one of the plates may include a wear-resistant and/or non-stick coating.

The front and rear edges of each plate which are hingedly coupled to the adjacent plates, may be formed with a corresponding tessellating and/or saw-tooth configuration. The hinged connection between the plates may comprise a flexible cord or a plurality of hinge pins.

The belt may comprise a plurality of plates having respective patterned relief surfaces which are spaced intermittently between plates without a patterned relief surface such that the resulting filter rod includes an impressed relief pattern on its outer surface at spaced intervals along its length.

The belt may be driven over a plurality of guide rollers, wherein at least one of the guide rollers may have a faceted outer surface and the belt may be in registration with the at least one guide roller such that the plates of the endless belt lie flat on a facet of the at least one guide roller as the belt passes over said guide roller.

The facets of the at least one guide roller may include a surface relief pattern corresponding to the patterned relief surface of the plates of the belt such that the patterned relief surface of the plates of the belt cooperate with the surface relief pattern on the facets of the at least one guide roller as the belt passes over said guide roller.

The belt may comprise a flexible band with a layer of resilient material formed thereon, and the patterned relief surface may be provided in the resilient material layer. The resilient material layer may be made of at least one of rubber or plastic.

In an alternative embodiment, the relief surface may be formed on an inner surface of the passage such that the filter material engages the relief surface and the relief pattern is impressed into the filter rod as the filter rod passes through the passage. Such relief surface may comprise one or more projections on an inner wall of the passage. Such projection(s) may be elongate rib(s) extending substantially longitudinally along at least part of the length of the passage. Alternatively, the or each projection may comprise nodes on an inner wall of the passage, for example, convex, pointed, pyramidal, square or frusto-conical/pyramidal protrusions.

The passage may be configured to heat the filter tow material as is passes therethrough. For example, the passage may include at least one inlet tube to allow steam to be introduced into the interior of the passage. Such inlet tube(s) may be formed in the side wall of the passage between distal first and second ends thereof. Alternatively, or in addition, the passage may include one or more heating elements formed integrally with the passage or provided on the passage. Such heating element(s) may comprise electrical heating element(s).

The passage may comprise a double wall structure along at least part of its length. The double wall structure may comprise an outer wall and an inner wall spaced from the outer wall to define a cavity therebetween. The inner wall may be perforated. The outer wall may include at least one inlet tube to allow steam to be introduced into the cavity between the outer and inner walls and, in an embodiment where the inner wall is perforated, to allow steam into interior of the passage. Alternatively, the inner wall may omit any perforations.

The apparatus may be configured such that the belt is formed into a tolled up state as it passes through the passage, such that the lateral edges of the belt are disposed proximate each other. The belt edges may be close to but spaced from each other, in abutment, or may overlap each other in said rolled up configuration of the belt. The passage may include a pressing member configured to impart an inward pressing force on the belt and/or filter rod as the filter rod is formed in the passage. Such a member may comprise a mechanism, which may include a sprung arm, and/or a roller biased inwardly towards the centre of the passage. The member/mechanism may be formed on in inside wall of the passage and may be provided at the top centre of the passage.

The belt or the passage may include a patterned relief surface configured to impress a grooved pattern on the outer surface of the filter rod as it is formed in the passage.

Also provided is a method of manufacturing a filter rod for a cigarette or other smoking article using a filter rod manufacturing apparatus as defined above wherein the passage includes a first open end for introduction of filter material and a second open end for expulsion of a formed filter rod, the passage narrowing between the first end and the second end so that as filter material is conveyed through the passage, it is compressed to form a filter rod, the method comprising feeding loose filter tow material onto the belt, conveying the filter tow material on the belt through the passage from the first open end to the second open end and thereby compressing the filter tow material to form a filter rod, and impressing a relief pattern on a surface of the filter rod as it passes through the passage.

The relief surface may be formed on the belt, and the method may further comprise the relief pattern being impressed on the surface of the filter rod by the patterned relief surface of the belt.

Alternatively, an inner surface of the passage may include the relief surface, and the method may further comprise the relief pattern being impressed on the surface of the filter rod by the patterned relief surface on in the inner surface of the passage.

The method may comprise feeding a plug wrap onto the belt and feeding the loose filter tow material onto the plug wrap, such that the formed filter rod is circumscribed by the plug wrap and the impressed relief pattern is formed on the filter rod through the plug wrap. Alternatively, the method may comprise circumscribing a plug wrap around the formed filter rod after it has exited from the passage. Yet further, the method may comprise feeding the filter tow material directly onto the belt such that the impressed pattern in the resulting filter rod is formed directly on the filter tow material without any plug wrap around the outer surface thereof.

A plasticiser may be entrained with the filter tow material, and the method may further comprise introducing heat and/or steam to the passage in order to activate and/or accelerate the reaction of the plasticiser with the filter tow material. The plasticiser may be entrained with the filter tow material in a ratio of at least 8% by weight to dry weight of filter tow material, and may be between 8-18%, and may be between 12-18%.

Embodiments of the invention are shown, by way of example only, in FIGS. 2 to 14 of the accompanying drawings, in which:

FIG. 1 shows an existing filter rod forming apparatus;

FIG. 2 shows a filter rod forming apparatus according to a first embodiment of the invention;

FIG. 3 shows an enlarged view of a section of the garniture belt of the apparatus of FIG. 2;

FIG. 4 shows a cross-section of the garniture belt of the apparatus of FIG. 2, in a rolled-up state;

FIG. 5 shows an enlarged view of a section of garniture belt of a filter rod forming apparatus according to a second embodiment of the invention;

FIG. 6 shows an enlarged view of a section of garniture belt of a filter rod forming apparatus according to a third embodiment of the invention;

FIG. 7 shows an enlarged view of a section of garniture belt of a filter rod forming apparatus according to a fourth embodiment of the invention;

FIG. 8 shows a filter rod forming apparatus according to a fifth embodiment of the invention;

FIG. 9A shows a cross-sectional view of the apparatus of FIG. 8 along the line X-X;

FIG. 9B shows a cross-sectional view of the apparatus of FIG. 8 along the line Y-Y;

FIG. 10 shows a filter rod forming apparatus according to a sixth embodiment of the invention;

FIG. 11 shows a filter rod forming apparatus according to a seventh embodiment of the invention;

FIG. 12 shows a cross-sectional view of the apparatus of FIG. 11 along the line Z-Z;

FIG. 13 shows a filter rod forming apparatus according to an eighth embodiment of the invention; and

FIG. 14 shows a cross-sectional view of the apparatus of FIG. 13 along the line W-W;

Referring now to FIG. 1, an existing apparatus 10 for producing a filter rod is shown and comprises a ‘garniture’ 11 and a guide funnel 12. The garniture 11 is a passage in the form of a duct or tube, having a wide entrance opening 11a and a narrow exit opening 11b. The garniture 11 narrows between the wide entrance opening 11a and the narrow exit opening 11b at a ‘tow guide’ portion 11c. The rear section 11d of the garniture 11 between the tow guide 11c and the narrow exit opening 11b is substantially constant in cross-section along its length (as shown in FIG. 1), but in some apparatuses may continue to taper but more gently than the tow guide section 11c. The tow guide section 11c transitions to the rear section 11d at a portion known as a ‘tongue’. The tongue may include a section of reduced taper than the tow guide portion. The garniture 11 is generally circular in cross-section. A continuous ‘garniture belt’ 13 extends through the garniture 11 and over a plurality of guide rollers 14 and is driven to be conveyed around the rollers 14 in the direction shown by arrows ‘A’. A plug wrap ‘P’ may be fed from a spool 15 onto the upper surface of the garniture belt 13 and is conveyed through the garniture 11 by the moving garniture belt 13. As the plug wrap P travels though the garniture 11, the shape of the tapered tow guide 11c (and tongue) deforms the garniture belt 13 and plug wrap P thereon such that, in cross-section, the plug wrap P goes from being flat (as it is on the spool 15) when it enters the wide entrance opening 11a of the garniture 11, to a closed circle as it leaves the narrow exit opening 11b of the garniture 11, completely surrounding the formed filter rod. As the plug wrap P is wrapped around the filter material, the edges meet to form a seam at an upper portion of the garniture 11. This seam may then be glued (or the plug wrap may be pre-glued where the seam is to be formed).

A section of the upper portion of the garniture 11 may comprise a heating bar (not shown) to heat and activate the glue at the seam of the plug wrap to adhere the plug wrap in place around the filter material. Such a heater bar may be curved and sit in a correspondingly shaped recess in the garniture 11 to form a continuous outer wall thereof. Furthermore, in some existing apparatuses, hot melt glue is applied to the plug wrap which needs to be cooled to set and adhere the seam together. In such cases, the heater bar would not be present and a cooling bar may be provided instead.

In use, loose filter tow material (not shown), such as loose cellulose acetate fibre, is fed into the funnel 12 as shown by arrow ‘B’ and is guided into the tow guide 11c of the garniture 11 by a ‘transport jet’ of compressed air from a jet nozzle (not shown). The filter tow material is conveyed through the tapering tow guide 11c on the plug wrap P so that the loose filter tow material is formed into a more compacted rod as it emerges from the distal narrow end 11b. The transport jet and guide funnel 12 serve to guide the loose filter tow material into the wide entrance opening 11a, and the transport jet provides a continuous blast of compressed air which gathers the loose filter tow material into a lightly compressed state and propels the lightly compressed filter tow material into the garniture 11.

As the filter tow material travels through the garniture 11 and is compressed, the plug wrap P is folded around the outside of the compressed cylinder of filter tow material and glue is applied to the over-lapping seam and heated to activate the glue, such that when the filter tow material exits though the narrow exit opening 11b of the garniture 11, the filter tow material is formed into a compressed cylindrical filter rod 16 enveloped by an outer plug wrap. This existing process produces filter rods with a smooth outer surface. If a relief pattern such as grooves are to be formed in the filter rods, these must either be formed in a separate second process requiring further machinery and production time/complexity, or the plug wrap P must first be shaped (e.g. crimped) prior to being fed into the garniture 11 so that the filter tow material conforms to the shape of the plug wrap P, again, involving further machinery and production time/complexity.

A method and apparatus 110 according to a first embodiment of the invention, for producing filter rods having a relief pattern on an outer surface thereof, is shown in FIGS. 2-4 and, as with the existing method/apparatus described above, comprises a guide duct or ‘garniture’ 111 having a wide entrance 111a and narrower exit 111b, and a guide funnel 112, the features of which are the same and/or function similarly as those described above in reference to FIG. 1. The apparatus 110 also includes a continuous belt or ‘garniture belt’ 113 which extends over a plurality of guide rollers 114 and is driven to be conveyed around the rollers 114 in the direction shown by arrows ‘C’ in FIG. 2. Also as with the existing filter rod producing apparatus, plug wrap ‘P’ is fed from a spool 115 onto the upper surface of the garniture belt 113 which conveys it through the garniture 111 which deforms the garniture belt 113 and plug wrap P thereon such that, in cross-section, the plug wrap P goes from being flat (as it is on the spool 115) when it enters the wide entrance opening 111a of the garniture 111, to a closed circle as it leaves the narrow exit opening 111b of the garniture 111, completely surrounding the formed filter rod.

The apparatus 110 of the first embodiment of the present invention differs from the existing apparatus 10 described above in the construction of the garniture belt 113 and the form of the guide rollers 114. In an existing apparatus 10, the garniture belt 13 is a continuous flexible belt of material such as canvas or other woven fibre. In the apparatus 110 of the first embodiment of the invention however, the garniture belt 113 is formed of a plurality of plates 117 hingedly connected to each other end-to-end. The construction of the garniture belt 113 can be seen more clearly in the enlarged portion of FIG. 2 and in FIG. 3, which shows the plates 117 are formed with a series of parallel ridges 118 and saw-toothed front and rear edges 119, 120. The plates 117 are connected together with saw-toothed front edge 119 tessellating with the saw-tooth rear edge 120 of the preceding plate 117, and a flexible connecting element 121 extending through apertures formed transversely through the saw-tooth sections 119, 120. The connecting element can be a flexible thread such as, but not limited to, plastic thread, metal wire, or fabric thread.

In order for the plates 117 to pass through the garniture 111, the plates 117 are elastically deformable from their flat state (shown in FIG. 3) to a rolled-up state (see FIG. 4) in which they are rolled about their longitudinal front/rear axis. In order for this deformation to occur, the connecting element 121 may be flexible to also deform between a straight configuration when the plates 117 are in their flat state to a curved configuration when the plates 117 are in their rolled-up state.

In order to minimise the stress on the plates 117 as they are continuously conveyed around the belt path of the garniture 111, the rollers 114 do not have a rounded/continuously curved outer surface as in an existing apparatus 10, but instead may have a series of flat faces 122 which are the same length as that of the plates 117. The garniture belt 113 length, position and dimensions of the rollers 114 and dimensions of the flat faces 122 thereof are configured such that as the garniture belt 113 passes over each roller 114, each plate 117 lies on a flat face 122 of the roller with the connecting element 121 aligned with the edge formed between adjacent flat faces 122. Therefore, the plates 117 are not forced to deform by curving about an axis transverse to their front/rear direction, as they would if they were to pass over round-faced rollers.

In use, as with an existing filter-rod forming apparatus, loose filter tow material (not shown), such as cellulose acetate, is fed into the funnel 112 as shown by arrow ‘D’ and is guided into the garniture 111 by a jet of compressed air from a jet nozzle (not shown). As the garniture belt 113 enters and is conveyed through the garniture 111, the plates 117 are deformed from their flat state to their rolled-up state shown in FIG. 4, and the filter tow material is conveyed through the tapered garniture 111 on the plug wrap P. By the time the garniture belt 113 reaches the narrow end 111b of the garniture 111, the flat plates 117 form a closed circle in cross-section, and the loose filter tow material is formed into a compact rod 116 circumscribed by the plug wrap P.

As the filter tow material travels through the garniture 111, the ridges 118 in the plates 117 impress a grooved pattern on the outer surface of the filter rod 116 so that when the filter rod 116 exits though the narrow exit opening 111b of the garniture 111, it has a series of longitudinal grooves formed around the entire perimeter of its outer surface. In order for the grooved pattern to remain set in the filter rod, the garniture 111 includes a heating means which accelerates the reaction of a plasticiser that is mixed with the cellulose acetate fibres to set the fibres in the shape formed by the plates 117 so that the shape remains in the resulting filter rod 116 once it emerges from the narrow exit opening 111b of the garniture 111. It will be appreciated that in the existing filter rod forming apparatus, it is less crucial that the filter shape is set so quickly—i.e. so that it sets when the filter rod 16 emerges from the garniture 11—since no pattern is formed in the surface of the filter rod which may be lost if the filter material is not set and is free to expand after exiting the garniture 11.

In the first embodiment of the invention shown in FIG. 2, the heating means comprises inlet ducts 124 along the length of the garniture 111 through which steam can be injected, as shown by arrows CS′. In order that the heat of the steam can be most efficiently applied to the cellulose acetate and plasticiser mix, the garniture belt 113 is preferably porous to allow steam therethrough. In the embodiment shown, the steam can pass through the garniture belt 113 at the gaps where the individual plates 117 are joined. However, it is also intended within the scope of the invention that further means may be provided to increase the porosity of the garniture belt, such as perforations formed in the plates 117 themselves.

The tapering of the garniture 111 from the wide open end 111a to the narrow exit end 111b also creates an inward pressure on the filter tow material as it passes therethrough which squeezes it and also helps the shaped pattern remain impressed on the resulting filter rod 116. In order for the shape to more effectively be retained in the filter rod 116, it may also be preferable for an increased amount of plasticiser to be mixed with the cellulose acetate fibres than would be used in existing rod manufacture. Around 4-8% of plasticiser by weight to dry weight of cellulose acetate tow may be used in existing processes, although in the filter rod manufacturing process of the invention, preferably an increased amount of plasticiser may be used, such as between 8-18% by weight to dry weight of cellulose acetate tow, and preferably between 12-18% by weight to dry weight of cellulose acetate tow.

FIG. 5 shows an enlarged close up view of a garniture belt 213, similar to the view of FIG. 3, of an apparatus 210 of a second embodiment of the present invention. The apparatus 210 differs from the apparatus 110 of the first embodiment in the configuration of the garniture belt 213, and all remaining features are the same as described previously and retain the same reference numerals. The garniture belt 213 comprises a plurality of linked plates 117 formed with a series of parallel ridges 118 and saw-toothed front and rear edges 119, 120, and the plates 117 are hingedly connected to each other end to end. However, unlike the apparatus 110 of the first-described embodiment, the plates 117 are not connected by a single flexible connecting element 121 but instead a plurality of connecting pins 221 link adjacent plates 117, one connecting pin 221 on each angled face of the saw-tooth sections 119, 120 connecting to the adjacent angled face of the saw-tooth section 119, 120 of the adjacent plate 117. The connecting pins 221 can be metal or plastic pins. Such connecting pins 221 may comprise ball and socket joints to allow flexibility of movement between individual pins. Alternatively, the pins 221 may include a pivot connector along their length between each plate to provide the garniture belt 213 with the required flexibility.

Operation of the apparatus of the second embodiment of the invention is the same as that described above for the first embodiment of the invention such that a formed filter rod 116 exits though the narrow exit opening 111b of the garniture 111 with a series of longitudinal grooves formed around the entire perimeter of its outer surface. However, in this embodiment, as the garniture belt 213 passes through the garniture 111 and the plates 117 are deformed from their flat configuration to their rolled-up state, the joins between the plates 117 are allowed to deform due to the plurality of individual connecting pins 221 being discrete items from one another, rather than the single connecting element 121 being a flexible component, as in the first embodiment of the invention.

FIG. 6 shows an enlarged close up view of a garniture belt 313, similar to the view of FIGS. 3 and 5, of an apparatus 310 of a third embodiment of the present invention. The apparatus 310 differs from the apparatuses 110, 210 of the first and second embodiments in the configuration of the garniture belt 313, and all remaining features are the same as described previously and retain the same reference numerals. Instead of comprising a plurality of linked plates as with the first and second embodiments of the invention, the garniture belt 313 comprises a continuous flexible belt 317a which has a flexible but resilient coating 317b formed on one side thereof which has a series of parallel ridges 318 extending in a longitudinal direction of the garniture belt 313. The coating 317b may be of a suitable resilient but preferably heat-resistant material such as plastic and/or rubber, and can be formed as a separate component and subsequently bonded to the underlying flexible belt 317a, or may be moulded onto the flexible belt 317a and set thereon with the desired surface relief pattern. The coating 317b is sufficiently flexible to enable the garniture belt 313 to deform into a rolled up state, similar to that shown in FIG. 4. In addition to the above, as the garniture belt 313 of the third embodiment of the invention is not made up of discrete plates joined together, the apparatus 310 may include existing curved-face rollers 14 instead of flat faceted rollers 114 of the first and second embodiments of the invention.

Operation of the apparatus 310 of the third embodiment of the invention is the same as that described above for the first embodiment of the invention such that a formed filter rod 116 exits though the narrow exit opening 111b of the garniture 111 with a series of longitudinal grooves formed around the entire perimeter of its outer surface. However, it is the ridges 318 in the resilient coating 317b which form the grooves/patterns in the filter rod as it passes through the garniture 111.

FIG. 7 shows an enlarged close up view of a garniture belt 413, similar to the view of FIGS. 3, 5 and 6, of an apparatus 410 of a fourth embodiment of the present invention. Depending on the implementation, the apparatus 410 may be similar or identical to that of the third embodiment of the invention except that instead of the resilient coating 317b being provided along the entire length of the flexible belt 317a, such a resilient coating 417b with a surface relief pattern in the form of ridges 418 is provided intermittently along the flexible belt 417a, such that a grooved/shaped pattern is only imparted onto the resulting filter rod intermittently or in any desired spacing.

As with the third embodiment of the invention, the coating 417b may be of a suitably resilient and preferably heat-resistant material such as rubber and/or plastic, and may be formed as a separate component and subsequently bonded to the underlying flexible belt 417a, or may be moulded onto the flexible belt 417a and set thereon with the desired surface relief pattern. Also, the coating 417b is sufficiently flexible to enable the garniture belt 413 to deform into a rolled up state, similar to that shown in FIG. 4, and the apparatus 410 may include existing curved-face rollers 14 instead of flat faceted rollers 114 of the first and second embodiments of the invention.

Operation of the apparatus 410 of the fourth embodiment of the invention may be similar to or the same as that described above for the third embodiment of the invention such that a formed filter rod 116 exits though the narrow exit opening 111b of the garniture 111 with a series of longitudinal grooves formed around the entire perimeter of its outer surface. However, in some implementations, the grooved pattern is only imparted onto the resulting filter rod intermittently.

In all of the garniture belts 213, 313, 413 of the second to fourth embodiments of the invention, additional means may be provided to increase the porosity of the garniture belts to improve the heat transfer of the steam to the cellulose acetate/plasticiser mix, such as perforations in the belt/plates.

A filter rod producing apparatus 510 of a fifth embodiment of the invention is shown in FIGS. 8, 9A and 9B, which is similar to the first embodiment shown in FIG. 2 and like features retain the same reference numerals. However, the apparatus 510 of the fifth embodiment of the invention has a differing configuration of the garniture 511. More specifically, the garniture 511 comprises a double-walled structure with a solid outer wall 511a and a perforated inner wall 511b, defining a cavity 512 therebetween. This is shown more clearly in FIGS. 9A and 9B which are cross-sectional views along the lines X-X and Y-Y of FIG. 8 respectively. The garniture 511 includes inlet ducts 124 to allow steam ‘S’ to be fed into the cavity 512 between the walls 511a, 511b of the garniture 511. The steam is then able to fill the cavity 512 and from there pass through the perforations 513 in the inner wall 511b to the garniture belt 113 within the garniture 511. As discussed above, the garniture belt 113 is preferably porous to as to allow the heat of the steam to more effectively transfer to the cellulose acetate and entrained plasticiser to effect the accelerated reaction and setting of the filter rod 116.

It will be appreciated that an advantage of the apparatus 510 of the fifth embodiment of the invention is that by having a double-walled garniture 511 and the cavity 512 therein, the steam is able to more effectively surround the garniture belt 113 and the filter rod 116 therein as it passes through the garniture 511, which enables a quicker and more efficient heat transfer to the filter rod material, improving the process of setting the shape formed in the surface of the filter rod 116. It is intended within the scope of the invention that the apparatus of the fifth embodiment of the invention may include a perforated garniture belt as described above, in order to further improve the heat transfer of the steam to the filter tow material and entrained plasticiser.

A filter rod producing apparatus 610 of a sixth embodiment of the invention is shown in FIG. 10, which is similar to the first embodiment shown in FIG. 2 and like features retain the same reference numerals. However, the apparatus 610 of the sixth embodiment of the invention includes a different configuration of the garniture 611. More specifically, the garniture 611 comprises heating elements 612 along its length. In this embodiment, no inlet ducts are provided for the introduction of steam into the garniture 611. Instead, the heat required to activate and accelerate the reaction of the plasticiser and the cellulose acetate of the filter material is provided directly by conduction from the heating element 612 through the wall of the garniture 611.

An advantage of the apparatus 610 of the sixth embodiment of the invention is that there is no requirement for any steam source to provide the heat for the plasticiser/cellulose acetate reaction. It will also be appreciated that as heat is transferred to the filter rod material by conduction, it is not necessary to provide a perforated/porous garniture belt 113. However, for optimum effectiveness of the apparatus 610 of the sixth embodiment of the invention, the material of the garniture belt 113 should preferably be a good conductor of heat, such as a metallic material, so that a quicker and more efficient heat transfer to the filter rod material can be achieved, improving the process of setting the shape formed in the surface of the filter rod 116.

The heating element 612 may be provided on an outer surface of the garniture 611, as shown in FIG. 10, or alternatively, may be formed integrally within the walls of the garniture 611. The heating element may preferably be an electric heating element.

A filter rod producing apparatus 710 of a seventh embodiment of the invention is shown in FIGS. 11 and 12, and is similar to the first embodiment shown in FIG. 2, with like features retaining the same reference numerals. However, the apparatus 710 of the seventh embodiment of the invention includes a different configuration of the garniture 711. More specifically, the garniture 711 comprises a pressure roller 712 in the interior of the garniture 711 at an upper portion thereof. This is shown more clearly in FIG. 12 which is a cross-sectional view along the line Z-Z of FIG. 11. The pressure roller 712 is positioned and configured to guide the lateral edges of the garniture belt 113 together as the garniture belt 113 is deflected into the rolled up configuration to surround the filter rod 116 being formed therein. The pressure roller 712 also serves to exert an inwards force on the garniture belt 113 where the two lateral edges meet, corresponding to the seam of the filter rod, in order to ensure the relief pattern is fully impressed on the filter rod 116 all the way around its circumference and to avoid a less pronounced pattern being formed at the point at which the lateral edges of the garniture belt 113 meet. It is intended within the scope of the invention that one or more pressure rollers may be provided and may be fixed within the garniture, or alternatively may be moveable and inwardly biased relative to the garniture passage. Furthermore, the or each toilet 712 may be formed as part of the heater (or cooling) bar (not shown) which may be present at an upper portion of the garniture 711, as described above.

A filter rod producing apparatus 810 of an eighth embodiment of the invention is shown in FIGS. 13 and 14 and, similarly to previously-described embodiments of the invention, is configured to form filter rods from loose filter tow material which include a grooved relief pattern formed on an outer surface thereof. The apparatus 810 comprises a garniture 811 having a wide entrance 811a and narrower exit 811b with a tapered ‘tow guide’ portion 811c therebetween, and a guide funnel 812 and transport jet, and a continuous garniture belt 813 which extends through the garniture 811 and over a plurality of guide rollers 814 and is driven to be conveyed around the rollers 114 in the direction shown by arrows ‘V’ in FIG. 13. As with the existing filter rod producing apparatus 10, plug wrap ‘P’ may be fed from a spool 815 onto the upper surface of the garniture belt 813 which conveys it through the garniture 811 such that it deforms into a rolled up configuration surrounding a compressed cellulose acetate filter rod, as described previously.

The apparatus 810 of the eighth embodiment of the invention differs from the previously-described embodiments at least in that the garniture belt 813 is not provided with any surface relief pattern to be impressed onto the filter rod as the garniture belt 813 and filter tow material are conveyed through the garniture 811. Instead, the garniture belt 813 is a thin continuous flexible belt of material. Furthermore, the inner wall of the garniture 811 is provided with a plurality of ribs 817 projecting inwardly and extending longitudinally towards the narrow exit opening 811b of the garniture 811. This can be seen more clearly in FIG. 14 which is a cross-sectional view of the garniture 811 taken along the line W-W in FIG. 13.

In use, loose filter tow material (not shown), such as cellulose acetate, is fed into the funnel 812 as shown by arrow ‘E’ and is guided into the garniture 811 by a transport jet of compressed air from a jet nozzle (not shown). As the garniture belt 813 enters and is conveyed through the garniture 811, the filter tow material is compressed by the inwardly tapering section and the plug wrap P is folded around the outside of the compressed cylinder of filter tow material, such that and when the filter tow material it exits though the narrow exit opening 811b of the garniture 811, the filter tow material is formed into a compressed cylindrical filter rod 816 enveloped by an outer plug wrap P.

As the filter tow material travels through the garniture 811, the ribs 817 on inner surface of the garniture wall impress a grooved pattern on the outer surface of the filter rod 816 so that when the filter rod 816 exits though the narrow exit opening 811b of the garniture 811, it has a series of longitudinal grooves formed around its outer surface. The ribs are preferably provided only in the narrow portion of the garniture 811 so that the grooves are only formed on the filter rod 816 once the filter tow material is substantially fully compressed and circumscribed with the plug wrap P. It will be appreciated that in this embodiment of the invention, the garniture belt 813 is sufficiently thin and flexible that the grooved shape can be effectively imparted onto the filter rod 816 by the ribs 817 though the thickness of the garniture belt 813.

In order for the grooved pattern to remain set in the filter rod, the garniture 811 includes a heating means which accelerates the reaction of a plasticiser that is mixed with the cellulose acetate fibres to set the fibres in the desired shape. In the embodiment shown in FIG. 13, the heating means comprises inlet ducts 824 along the length of the garniture 811 through which steam can be injected, as shown by arrows ‘S’, as described previously in respect of the first embodiment of the invention. Accordingly, as also described previously, in order that the heat of the steam can be most efficiently applied to the cellulose acetate and plasticiser mix, the garniture belt 813 may be porous to allow steam therethrough, for example, the material of the garniture belt 813 itself may be porous, or the garniture belt 813 may include means to increase the porosity of the garniture belt, such as perforations. For example, the garniture belt may be formed from a perforated metal which is resiliently deformable to pass over the rollers 814 and roll up within the garniture 811 and deform to the shape of the interior wall of the garniture 811. Such a metallic perforated garniture belt would exhibit the advantages of being porous to allow steam to pass therethrough, and also conductive to allow heat to be efficiently transferred from the heating means to the filter rod 816.

It is also intended within the scope of the invention that double wall structure described above with reference to the fifth embodiment of the invention, and the alternative heating means described above with reference to the sixth embodiment of the invention, could be applied to the alternative garniture 811 of the apparatus 810 of the eighth embodiment of the invention.

In the first to seventh embodiments of the invention shown and described above, the garniture belts 113, 213, 313, 413, 513, 613, 713 include longitudinal grooves formed thereon to impart a corresponding shape to the outer surface of the resulting filter rod. However, the invention is not intended to be limited to a method and apparatus for forming grooved filter rods, and it is intended within the scope of the invention that other shapes could be formed on filter rods by correspondingly shaped relief patterns being formed on the garniture belts, such as helical grooved, circumferential grooves, discrete depressions or any other combination/pattern of recesses/protrusions. Also, with regard to embodiments of the invention which include a garniture belt of connected plates, not every plate of the garniture belt necessarily includes a shaped/grooved pattern thereon to impart a corresponding shape to the filter rod. Instead, such a pattern could be provided on every other plate only, or every third plate, or any other variation, such that the grooved/shaped pattern is only imparted onto the resulting filter rod intermittently or in any desired spacing, as per the order of the shaped/non-shaped garniture belt plates. In such an embodiment, those plates which do not include a relief pattern thereon to impart a shape to the filter rod may not necessarily be formed of the same material as the shaped plates. For example, the sections of garniture belt between the shaped plates may be of existing woven belt construction. Yet further, the plates of the garniture belt shown and described above are of metallic construction although they maybe of other suitable material that is sufficiently rigid to impart the shaped pattern on the filter rod within the garniture, but is also elastically deformable to be able to roll up on itself to fit into the garniture. Such materials could include plastic or rubber. However, metal plates, such as copper or aluminium, or even gold, provide the additional advantage of good heat conductivity to allow the heat from the steam or other heat source to quickly pass to the filter tow material and entrained plasticiser to effect the shaping and setting of the filter rod. It is also intended within the scope of the invention that the plates of the garniture belt may be coated with a coating which may improve wear resistance and/or be a non-stick coating such as PTFE, titanium or a carbonised coating. The lateral edges of the garniture belts of the invention are intended to at least meet in the fully rolled up configuration with in the garniture, although they may also overlap in the most rolled up configuration, within the scope of the invention.

It is intended that the various embodiments of the invention described above may comprise a garniture belt formed of a single band with the intended relief pattern to be imparted on the filter rod, formed on the surface thereof, instead of the garniture belt comprising a plurality or articulated plates. Such a band could be made of sufficiently deformable material to enable it to pass over rollers of the apparatus, and deflect into a rolled up configuration within the garniture, but also be resilient enough that the relief pattern thereon can be impressed into the surface of the filter rod being formed. Such a garniture belt may preferably be made of a conductive material such as metal, preferably aluminium, to efficiently conduct heat from a heat means to the filter rod being formed. Furthermore, the garniture belt may include perforations to enable steam in embodiments of the invention where steam is used as a heating source, of more effectively be transferred to the filter rod being formed to transfer heat thereto.

All embodiments of the invention shown and described above include a plug wrap P being fed into the garniture and onto which the loose filter tow material is directed, such that the resulting filter rod 116 comprises filter material wrapped in the plug wrap. However, it is intended within the scope of the invention that the plug wrap may be omitted and instead, the filter tow material may be fed directly onto the garniture belt which conveys the filter material through the garniture, compresses it into a filter rod and forms the desired relief pattern on the outer surface thereof. In such an embodiment of the invention, the filter rod produced would remain in the desired rod form with the surface pattern thereon purely due to the compression exerted by the garniture belt within the garniture and the activation of the plasticiser entrained in the filter material. As a further alternative intended to fall within the scope of the invention, a plug wrap-coated filter rod may be produced but instead of the plug wrap P being introduced together with the loose filter tow material into the garniture, the filter rod with surface relief pattern may be formed in the garniture without a plug wrap, as described above, and the plug wrap may be subsequently wrapped around the formed filter rod once it has exited the garniture. Such an embodiment is shown as an in dashed lines in FIG. 2 as an alternative configuration of the first embodiment of the invention, in which a plug wrap P′ is fed from a spool 115′ and is wrapped around the filter rod 116 after it is has been formed in, and exited from, the garniture 111. The plug wrap P′ may be wrapped around the filter rod such that the plug wrap P′ conforms to the relief pattern formed on the surface of the filter rod 116, so that the finished filter rod with outer plug wrap P′ exhibits the desired surface relief pattern on its outer surface. Although shown in FIG. 2 as an alternative configuration of the apparatus of the first embodiment of the invention, it is intended that this alternative arrangement of plug wrap application could be used in any of the other embodiments of the invention described above.

In the embodiments of the invention shown and described above which include a garniture belt made of a plurality of articulated plates, the rollers around which the garniture belt passes is described as being faceted to correspond to the individual plates of the garniture belt. However, the invention is not limited to such roller configuration and instead, other rollers may be used, for example rollers with a deformable outer surface, such as rubber or plastic/polymer, to provide a softer surface against which the garniture belt may lie and which may deform to hold the shape of the garniture belt/plates. Alternatively, the rollers may include a plurality of recesses corresponding to the individual plates of the garniture belt, and which receive each garniture belt plate as the garniture belt passes over the roller. Yet further, the rollers may be of an increased diameter so that the garniture belt plates are less deformed on the large curved roller surface.

Embodiments of the invention shown and described above are examples only and the invention is not intended to be limited to these specific examples. Furthermore, it is intended that the present invention may include any combination of non-mutually exclusive features described above, and is as defined by the scope of the claims hereafter.

Methods and Apparatuses for Manufacture of Smoking Article Filters

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