METHOD OF MANUFACTURING A TUBULAR ELEMENT FOR AN AEROSOL-GENERATING PRODUCT USING A SINGLE SHEET OF SHEET MATERIAL

Abstract

A method of manufacturing a tubular element for an aerosol-generating article, the tubular element having a first tubular portion and a second tubular portion, the method comprising: providing a sheet of web material having a first sheet portion corresponding to the first tubular portion and a second sheet portion corresponding to the second tubular portion; cutting a cutout from an edge of the sheet of web material to form a discontinuous edge (S1), the cutout being cut from the first sheet portion or the second sheet portion such that the dimensions of the first and second sheet portions are different in a direction substantially perpendicular to a winding axis, the discontinuous edge being substantially parallel to the winding axis; and winding the sheet of web material about the winding axis to form the tubular element (S3).

Description

[0001] A METHOD OF MANUFACTURING A TUBULAR ELEMENT FOR AN AEROSOLGENERATING ARTICLE USING A SINGLE SHEET OF WEB MATERIAL

[0002] The present disclosure relates to a method of manufacturing a tubular element for an aerosol-generating article. The present disclosure also relates to an aerosol-generating article manufactured using the method. The aerosol-generating article comprises an aerosolgenerating substrate for generating an inhalable aerosol, for example, upon heating.

[0003] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than combusted, are known in the art. Typically, in such heated aerosol-generating articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] A number of aerosol-generating devices for consuming heated aerosol-generating articles are known in the art. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosolgenerating devices have been proposed that comprise an internal resistive heater blade which is adapted to be inserted into the aerosol-generating substrate. As an alternative, inductively heatable aerosol-generating articles comprise a susceptor element arranged within the aerosol-generating substrate that can be heated by an alternating magnetic field provided by the aerosol-generating device.

[0005] Heated aerosol-generating articles are typically cigarette-shaped and comprise a plurality of elements or plugs. For example, such articles typically comprise a substrate plug including an aerosol-generating substrate, a tubular plug downstream of the substrate plug and a mouthpiece filter plug at a mouth end of the article. The tubular plug has an internal cavity or empty core that defines an airflow pathway. It is known to have two tubular plugs: a first tubular plug that functions as a spacer between the substrate plug and other components of the aerosol-generating article; and a separate second tubular plug that functions as an air cooler for cooling air as it passes through the aerosol-generating article to help form an aerosol. The second tubular plug generally abuts the first tubular plug.

[0006] Aerosol-generating articles in the form of inhaler articles, such as dry powder inhalers, are known in the art. Some dry powder inhalers have a component for storing the dry powder, such as a capsule. The capsule may be activated by being pierced by a separate piercing element, such as a piercing element of a holder. Once the capsule has been activated, a consumer may draw on a mouth end of the inhaler to generate an air flow through the inhaler. Each air flow from each inhalation may carry a portion of the dry powder from the capsule to the lungs of the user. Such aerosol-generating articles may generate an aerosol without heating.

[0007] Aerosol-generating articles such as dry powder inhalers generally comprise a retention plug or element having a cavity or empty core that defines an airflow pathway and which helps to hold, or otherwise resist movement of, the capsule so that the capsule can be easily pierced. Such retention plugs are typically formed of two tubular plugs: a first tubular plug that extends across and is fixed to an interior of the aerosol-generating article; and a second separate smaller tubular plug fixed to the first tubular plug on a side of the first tubular plug facing the capsule. The smaller diameter of the second tubular plug provides a well or gutter between its external tubular surface and an internal surface of the aerosol-generating article that collects dry powder and reduces the likelihood of the dry powder leaking out of the article once the capsule has been pierced, for example, if the article is inclined.

[0008] Manufacturing and assembling the first and second tubular plugs of both heated aerosol-generating articles and non-heated aerosol-generating articles such as dry powder inhalers can be difficult because the airflow is restricted to their internal cavities. The ability of the first and second tubular plugs to perform their respective functions depends on how accurately they are positioned and aligned. The quality and consistency of a consumer experience may depend on the internal air path through the aerosol-generating article and therefore it is important that the first and second tubular plugs are abutted and concentric. Furthermore, aerosol-generating article can be susceptible to breakage at the interface between the first and second tubular plugs when a force is applied to the aerosol-generating article, for example, during insertion of the aerosol-generating article into an aerosolgenerating device.

[0009] It would be desirable to provide a method of manufacturing an aerosol-generating article that reduces the need for accurate positioning and alignment of tubular plugs or elements.

[0010] According to an example of the present disclosure, there is provided a method of manufacturing a tubular element for an aerosol-generating article. The tubular element may have a first tubular portion. The tubular element may have a second tubular portion. The method may comprise providing a sheet of web material having a first sheet portion corresponding to the first tubular portion. The method may comprise providing a sheet of web material having a second sheet portion corresponding to the second tubular portion. The method may comprise cutting a cutout from an edge of the sheet of web material to form a discontinuous edge. The cutout may be cut from the first sheet portion or the second sheet portion. The dimensions of the first and second sheet portions may be different in a direction substantially perpendicular to a winding axis. The discontinuous edge may be substantially parallel to the winding axis. The method may comprise winding the sheet of web material about the winding axis to form the tubular element.

[0011] According to an example of the present disclosure, there is provided a method of manufacturing a tubular element for an aerosol-generating article. The tubular element has a first tubular portion and a second tubular portion. The method comprises: providing a sheet of web material having a first sheet portion corresponding to the first tubular portion and a second sheet portion corresponding to the second tubular portion; cutting a cutout from an edge of the sheet of web material to form a discontinuous edge, the cutout being cut from the first sheet portion or the second sheet portion such that the dimensions of the first and second sheet portions are different in a direction substantially perpendicular to a winding axis, the discontinuous edge being substantially parallel to the winding axis; and winding the sheet of web material about the winding axis to form the tubular element.

[0012] The term “aerosol-generating article” is used herein to denote an article in which an inhalable aerosol is generated from an aerosol-generating substrate and delivered to a consumer. As used herein, the term “aerosol-generating substrate” denotes a substrate from which an aerosol can be formed or generated. For example, the aerosol-generating substrate may be capable of releasing volatile compounds upon heating to generate an aerosol. Alternatively, the aerosol-generating substrate may comprise particles that can be entrained in an airflow to generate an aerosol.

[0013] As used herein, the term "tubular element" denotes a generally hollow elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term "tubular" will be used with reference to a tubular element having a substantially cylindrical cross-section and defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it will be understood that alternative geometries (for example, alternative cross-sectional shapes) of the tubular element may be possible. The tubular element is an individual, discrete component of the aerosol-generating article.

[0014] Advantageously, by providing a cut-out sheet of web material comprising first and second sheet portions having different dimensions in a direction substantially perpendicular to a winding axis, a tubular element can be formed in which the first tubular portion and second tubular portion are accurately positioned and aligned. Advantageously, by providing a cut-out sheet of web material comprising first and second sheet portions having different dimensions in a direction substantially perpendicular to a winding axis, a tubular element can be formed having first and second tubular portions with different internal or external diameters.

[0015] The tubular element may be formed from a single sheet of web material. The tubular element may be formed as a unitary element. The term “unitary element” is used herein to refer to a tubular element that is formed as a single piece or element. This is in contrast to an aerosol-generating article that may have separate tubular elements corresponding to the first and second tubular portions of the tubular element described herein and which have to be assembled. The tubular element may be formed as a unitary element by being made from a single piece of material, for example, a single sheet of web material.

[0016] By forming the tubular element as a unitary element, the tubular element is advantageously formed as a single piece. This helps to alleviate any difficulties in positioning the first and second tubular portions relative to each other during assembly of the aerosolgenerating article compared to forming the first and second tubular portions as separate elements. There is no need to accurately bring the first and second tubular portions into abutting engagement during assembly of the aerosol-generating article because the unitary tubular element is already assembled and automatically achieves the advantages of this configuration. The unitary nature of the tubular element also helps to ensure that the first and second tubular portions are axially aligned. This ensures a smooth airflow through the tubular element and helps to provide a consistent consumer experience.

[0017] The sheet of web material may be cut to form a polygon. The polygon may have at least one corner that subtends an internal angle of 270 degrees. As used herein, the term “internal angle” refers to an angle subtended within the shape of the sheet and not outside the shape of the sheet. Advantageously, this ensures that the cut-sheet is not a square or a rectangle and has first and second sheet portions with different dimensions.

[0018] The sheet may comprise a plurality of first and second portions. Winding the sheet may form a tubular subassembly comprising a plurality of joined tubular elements. Advantageously, this allows multiple tubular elements to be formed from a single winding process.

[0019] The sheet may comprise double-length first sheet portions and double-length second sheet portions such that the tubular subassembly comprises symmetrical pairs of tubular elements.

[0020] The method may further comprise cutting the tubular subassembly to separate individual tubular elements.

[0021] The sheet may have a continuous edge opposite the discontinuous edge. As used herein, the term “continuous edge” is intended to denote an edge without a cutout, for example, a straight edge of the sheet of web material. The continuous edge may help to provide either an internal diameter or external diameter that is uniform over the whole length of the tubular element.

[0022] In one example, the sheet may be wound starting from the discontinuous edge to form a tubular element having a first tubular portion with a first internal diameter and a second tubular portion with a second internal diameter. Advantageously, this results in the first internal diameter being different to the second internal diameter.

[0023] The sheet may be wound around a central mandrel having a longitudinal axis that extends along the winding axis. The central mandrel may have a plurality of winding sections arranged along its longitudinal axis. The winding sections may have external diameters corresponding to the first and second internal diameters of the first and second tubular portions respectively.

[0024] The winding sections may be assembled to, and disassembled from, the mandrel.

[0025] In another example, the sheet may be wound starting from the continuous edge to form a tubular element having a first tubular portion with a first external diameter and a second tubular portion with a second external diameter. Advantageously, this results in the first external diameter being different to the second external diameter.

[0026] The sheet may be wound around a central mandrel having a longitudinal axis that extends along the winding axis. The central mandrel may have a substantially uniform diameter along its longitudinal axis.

[0027] In another example, the discontinuous edge may comprise a first discontinuous edge and the tubular element may comprise a third tubular portion. The method may comprise providing a sheet of web material having a third sheet portion corresponding to the third tubular portion. The method may comprise cutting a cutout from an edge of the sheet of web material opposite the first continuous edge to form a second discontinuous edge. The cutout may be cut from the third sheet portion. The method may comprise winding the sheet starting from the first discontinuous edge to form a tubular element having different first and second internal diameters respectively and the third tubular portion has a different external diameter to the first and second tubular portions. Alternatively, the method may comprise winding the sheet starting from the second discontinuous edge to form a tubular element having different first and second external diameters respectively and the third tubular portion has a different internal diameter to the first and second tubular portions.

[0028] The sheet of web material may have a thickness between 0.05 millimetres and 0.2 millimetres, optionally between 0.07 millimetres and 0.12 millimetres, further optionally between 0.08 millimetres and 0.10 millimetres. In one example, the sheet of web material may have a thickness of about 0.09 millimetres.

[0029] The method may further comprise applying a glue or adhesive to the sheet of web material prior to winding. The glue or adhesive may be applied on an upper surface of the sheet. The glue or adhesive may be applied on a lower surface of the sheet. The glue or adhesive may be applied over an entire surface of the sheet. The glue or adhesive may be applied to part of a surface of the sheet. The glue or adhesive may be applied in strips or patches. The glue or adhesive may be applied by a glue nozzle or roller. The glue or adhesive may comprise a fast-acting glue such as ethylene-vinyl acetate (EVA). The glue or adhesive may comprise a long lasting glue such as poly-vinyl acetate (PVA). In the wound state of the tubular element or subassembly, the glue or adhesive may have a thickness between 2 micrometres and 10 micrometres, optionally between 3 micrometres and 8 micrometres and further optionally between 4 micrometres and 6 micrometres. In one example, the glue or adhesive may have a thickness of about 5 micrometres.

[0030] The method may further comprise applying heat to dry the adhesive following winding.

[0031] The method may further comprise pressing an external surface of the sheet during winding using peripheral rollers or wheels.

[0032] According to an example of the present disclosure, there is provided a method of manufacturing a tubular element for an aerosol-generating article. The method may comprise providing a sheet of web material. The sheet of web material may have continuous end edges extending parallel to a winding axis. The method may comprise cutting a cutout from a lateral edge of the sheet of web material. The lateral edge may be perpendicular to the winding axis, wherein the cutout is cut at a point along the length of the sheet between the end edges to form a discontinuous lateral edge. The method may comprise winding the sheet of web material about the winding axis to form the tubular element.

[0033] According to an example of the present disclosure, there is provided a method of manufacturing a tubular element for an aerosol-generating article. The method comprises providing a sheet of web material, the sheet of web material having continuous end edges extending parallel to a winding axis; cutting a cutout from a lateral edge of the sheet of web material, the lateral edge being perpendicular to the winding axis, wherein the cutout is cut at a point along the length of the sheet between the end edges to form a discontinuous lateral edge; winding the sheet of web material about the winding axis to form the tubular element.

[0034] The cutout may have any suitable shape. In one example, the cutout may have a triangular shape. In another example, the cutout may have a rectangular shape.

[0035] The cutout may be a first cutout and may be cut from a first lateral edge. The method may further comprise cutting a second cutout from a second opposing lateral edge of the sheet of web material. The first and second cutouts may be mirror images of each other.

[0036] The sheet of web material may comprise a plurality of sheet portions arranged consecutively along a width of the sheet of web material. Each sheet portion may correspond to a tubular element. Winding the sheet may form a tubular subassembly comprising a plurality of joined tubular elements.

[0037] The method may further comprise cutting a series of cutouts from the sheet of web material. The series of cutouts may be arranged in a row across the width of the sheet of web material at a point along the length of the sheet. The cutouts may straddle or be cut on either side of a line of interface between adjacent sheet portions.

[0038] Each cutout of the series of cutouts may have twice the width of the first and second cutouts. Each cutout of the series of cutouts may be symmetrical. Each cutout of the series of cutouts may have a line of symmetry arranged along the line of interface between adjacent sheet portions.

[0039] The method may further comprise cutting the tubular subassembly along each line of interface to separate individual tubular elements.

[0040] According to another example of the present disclosure, there is provided a method of manufacturing an aerosol-generating article. The method may comprise manufacturing a tubular element according to any of the above-described example methods. The method may comprise providing a substrate element comprising an aerosol-generating substrate.

[0041] According to another example of the present disclosure, there is provided a method of manufacturing an aerosol-generating article. The method comprises: manufacturing a tubular element according to any of the above-described example methods, and providing a substrate element comprising an aerosol-generating substrate.

[0042] The tubular element may be arranged downstream of the substrate element.

[0043] The method may further comprise providing an upstream element. The upstream element may be arranged upstream of the substrate element.

[0044] The method may further comprise providing a mouthpiece element. The mouthpiece element may be arranged downstream of the tubular element.

[0045] The method may further comprise wrapping at least the substrate element and tubular element in a wrapper to form a wrapped subassembly.

[0046] The method may further comprise joining the mouthpiece element to the wrapped subassembly using a tipping paper.

[0047] According to an example of the present disclosure, there is provided an aerosolgenerating article. The aerosol-generating article may comprise a substrate element comprising an aerosol-generating substrate. The aerosol-generating article may comprise a tubular element. The tubular element may comprise a first tubular portion. The tubular element may comprise a second tubular portion. The first tubular portion may constitute at least 10 percent of the length of the tubular element. The second tubular portion may constitute at least 10 percent of the length of the tubular element. The tubular element may be formed as a unitary element

[0048] In one example, the first tubular portion may have a first internal diameter. The second tubular portion may have a second internal diameter. The first internal diameter may be different to the second internal diameter.

[0049] In another example, the first tubular portion may have a first external diameter. The second tubular portion may have a second external diameter. The first external diameter may be different to the second external diameter.

[0050] According to an example of the present disclosure, there is provided an aerosolgenerating article comprising: a substrate element comprising an aerosol-generating substrate; and a tubular element a first tubular portion and a second tubular portion. The first tubular portion and second tubular portion each constitute at least 10 percent of the length of the tubular element. The tubular element is formed as a unitary element. The first tubular portion has a first internal diameter and the second tubular portion has a second internal diameter and the first internal diameter is different to the second internal diameter. Alternatively or in addition, the first tubular portion has a first external diameter and the second tubular portion has a second external diameter and the first external diameter is different to the second external diameter.

[0051] With respect to the aerosol-generating article, the term “length” denotes the dimension of a component of the aerosol-generating article in the longitudinal direction of the aerosolgenerating article. The longitudinal direction of the aerosol-generating article refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms “upstream” and “downstream” describe the relative positions of elements, or portions of elements, of the aerosol-generating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use.

[0052] The first tubular portion and second tubular portion may each constitute at least 20 percent of the length of the tubular element, preferably at least 30 percent of the length of the tubular element, and more preferably at least 40 percent of the length of the tubular element. In a preferred example, the first tubular portion and second tubular portion may each constitute about 50 percent of the length of the tubular element.

[0053] In one example aerosol-generating article, the first and second tubular portions may have different first and second internal diameters respectively. The second tubular portion may be arranged downstream of the first tubular portion. The second internal diameter may be greater than the first internal diameter. The second internal diameter may be at least 1 millimetre greater than the first internal diameter. Optionally, the second internal diameter may be at least 1.2 millimetres greater than the first internal diameter. Optionally, the second internal diameter may be at least 1.4 millimetres greater than the first internal diameter. Optionally, the second internal diameter may be at least 1.6 millimetres greater than the first internal diameter. Optionally, the second internal diameter may be at least 1.8 millimetres greater than the first internal diameter. Optionally, the second internal diameter may be at least 2.0 millimetres greater than the first internal diameter.

[0054] The difference between the first and second internal diameters may be between about 0.5 and about 2.5 millimetres, optionally between about 1 millimetre and about 2.5 millimetres and further optionally between about 1 .5 millimetres and about 2.0 millimetres. In a preferred example, the difference between the first and second internal diameters may be about 1.7 millimetres.

[0055] A ratio of the second internal diameter to the first internal diameter may be between 1.2 and 2.5, optionally between 1.2 and 2.0, further optionally between 1.3 and 1.7 and yet further optionally between 1.4 and 1.6. In one example, a ratio of the second internal diameter to the first internal diameter may be about 1.4. In another example, a ratio of the second internal diameter to the first internal diameter may be between about 2.0 and about 2.5.

[0056] The tubular element may be hollow. The tubular element may be hollow over its entire length.

[0057] The first tubular portion of the tubular element may define a first internal cavity of the tubular element that extends from an upstream end of the first tubular portion to a downstream end of the first tubular portion. The first internal diameter being an internal diameter of the first internal cavity. The first internal cavity may define at least part of an airflow pathway through the tubular element. The first internal cavity may be substantially empty to allow substantially unrestricted airflow along the first internal cavity.

[0058] The second tubular portion of the tubular element may define a second internal cavity of the tubular element that extends from an upstream end of the second tubular portion to a downstream end of the second tubular portion. The second internal cavity may define at least part of an airflow pathway through the tubular element. The second internal cavity may be substantially empty to allow substantially unrestricted airflow along the second internal cavity.

[0059] The tubular element may be arranged in alignment with, and downstream of, the substrate element. In a preferred example, the tubular element is located immediately downstream of the substrate element. An upstream end of the tubular element may abut a downstream end of the substrate element. The tubular element preferably has an external diameter that is approximately equal to the external diameter of the substrate element and to the external diameter of the aerosolgenerating article.

[0060] The tubular element may have an external diameter of between 5 millimetres and 12 millimetres, for example of between 5 millimetres and 10 millimetres or of between 6 millimetres and 8 millimetres. In a preferred example, the tubular element has an external diameter of 7.1 millimetres plus or minus 10 percent.

[0061] The first tubular portion of the tubular element may have an internal diameter of at least about 2.5 millimetres, preferably at least about 3.0 millimetres, and more preferably at least about 3.5 millimetres. Alternatively or in addition, the first tubular portion of the tubular element may have an internal diameter of less than about 4.0 millimetres, preferably less than about 3.5 millimetres or less than about 3.0 millimetres.

[0062] The first tubular portion of the tubular element may have an internal diameter between about 2.0 millimetres and about 4.0 millimetres, preferably between about 2.5 millimetres and about 3.5 millimetres, and more preferably between about 3.0 millimetres and 3.5 millimetres. In a preferred example, the first tubular portion of the tubular element may have an internal diameter of about 3.3 millimetres.

[0063] A peripheral wall of the first tubular portion may have a thickness of at least about 1 millimetre, preferably at least about 1 .5 millimetres or at least about 2 millimetres. Alternatively or in addition, a peripheral wall of the first tubular portion may have a thickness of less than about 3 millimetres, preferably less than about 2.5 millimetres or less than about 2 millimetres.

[0064] A peripheral wall of the first tubular portion may have a thickness between about 1 millimetre and about 3 millimetres, preferably between about 1.5 millimetres and about 2.5 millimetres and more preferably between about 1.5 millimetres and 2.0 millimetres. In a preferred example, a peripheral wall of the first tubular portion may have a thickness of about 1.9 millimetres.

[0065] The first tubular portion of the tubular element may have a length of at least about 5 millimetres, preferably at least about 6 millimetres and more preferably at least about 7 millimetres. The first tubular portion of the tubular element may have a length of less than about 15 millimetres, preferably less than about 12 millimetres and more preferably less than about 10 millimetres.

[0066] The first tubular portion of the tubular element may have a length between about 5 millimetres and about 15 millimetres, preferably between about 6 millimetres and 12 millimetres, and more preferably between about 7 millimetres and 10 millimetres. In a preferred example, the first tubular portion of the tubular element may have a length of about 8 millimetres or about 9 millimetres. The second tubular portion of the tubular element may have an internal diameter of at least about 4.0 millimetres, preferably at least about 4.5 millimetres, and more preferably at least about 5.0 millimetres. Alternatively or in addition, the second tubular portion of the tubular element may have an internal diameter of less than about 6.0 millimetres, preferably less than about 5.5 millimetres or less than about 5.0 millimetres.

[0067] The second tubular portion of the tubular element may have an internal diameter between about 4.0 millimetres and about 6.0 millimetres, preferably between about 4.5 millimetres and about 6.0 millimetres, and more preferably between about 4.5 millimetres and 5.5 millimetres. In a preferred example, the second tubular portion of the tubular element may have an internal diameter of about 5.0 millimetres.

[0068] A peripheral wall of the second tubular portion may have a thickness of at least about 0.3 millimetres, preferably at least about 0.6 millimetres, and more preferably at least about 0.9 millimetres. Alternatively or in addition, a peripheral wall of the second tubular portion may have a thickness of less than about 2.5 millimetres, preferably less than about 2.0 millimetres, and more preferably less than about 1.5 millimetres.

[0069] A peripheral wall of the second tubular portion may have a thickness between about 0.3 millimetres and 2.5 millimetres, preferably between about 0.6 millimetres and 2.0 millimetres, and more preferably between about 0.9 millimetres and 1.5 millimetres. In a preferred example, a peripheral wall of the second tubular portion may have a thickness of about 1.05 millimetres.

[0070] The second tubular portion of the tubular element may have a length of at least about 5 millimetres, preferably at least about 6 millimetres and more preferably at least about 7 millimetres. The second tubular portion of the tubular element may have a length of less than about 15 millimetres, preferably less than about 12 millimetres and more preferably less than about 10 millimetres.

[0071] The second tubular portion of the tubular element may have a length between about 5 millimetres and about 15 millimetres, preferably between about 6 millimetres and 12 millimetres, and more preferably between about 7 millimetres and 10 millimetres. In a preferred example, the second tubular portion of the tubular element may have a length of about 8 millimetres.

[0072] The internal diameter of first tubular portion may taper continuously along the length of the first tubular portion. The internal diameter of second tubular portion may taper continuously along the length of the second tubular portion.

[0073] In another example aerosol-generating article, the first and second tubular portions may have different first and second external diameters respectively.

[0074] The substrate element may comprise a capsule containing an aerosol-generating substrate. The capsule may be arranged upstream of the tubular element.

[0075] The first external diameter may be less than the second external diameter. The external surface of the first tubular portion of the tubular element having a smaller first external diameter may define, at least in part, an annular space within the aerosol-generating article. Advantageously, the annular space may define a gutter or well that collects excess aerosolgenerating substrate that is released from the capsule. The annular space may also collect aerosol-generating substrate that is released from the capsule when the aerosol-generating article is moved around between consumer inhalations.

[0076] The first external diameter may be at least 1 millimetre less than the second external diameter. Optionally, the first external diameter may be at least 2 millimetres less than the second external diameter. Further optionally, the first external diameter may be at least 3 millimetres less than the second external diameter.

[0077] The difference between the first and second external diameters may be between about 0.5 and about 3.5 millimetres, optionally between about 1 millimetre and about 3 millimetres and further optionally between about 1.5 millimetres and about 2.5 millimetres. In a preferred example, the difference between the first and second external diameters may be about 2 millimetres.

[0078] A ratio between the second external diameter and the first external diameter may be between 1.2 and 1.8, preferably between 1.3 and 1.6 and more preferably between 1.3 and 1.5. In a preferred example, a ratio between the second external diameter and the first external diameter may be about 1 .4.

[0079] The tubular element may be hollow. The tubular element may be hollow over its entire length.

[0080] The tubular element may define an internal cavity that extends from an upstream end of the tubular element to a downstream end of the tubular element. The internal cavity may define an airflow pathway through the tubular element. The internal cavity may be substantially empty to allow substantially unrestricted airflow along the internal cavity.

[0081] The first tubular portion of the tubular element may have an external diameter of at least about 4.0 millimetres, preferably at least about 4.5 millimetres, and more preferably at least about 5.0 millimetres. Alternatively or in addition, the first tubular portion of the tubular element may have an external diameter of less than about 7.0 millimetres, preferably less than about 6.5 millimetres or less than about 6.0 millimetres.

[0082] The first tubular portion of the tubular element may have an external diameter between about 4.0 millimetres and about 7.0 millimetres, preferably between about 4.0 millimetres and about 6.0 millimetres, and more preferably between about 4.5 millimetres and 5.5 millimetres. In a preferred example, the first tubular portion of the tubular element may have an external diameter of about 5.0 millimetres.

[0083] A peripheral wall of the first tubular portion may have a thickness of at least about 0.5 millimetres, preferably at least about 1 .0 millimetre or at least about 2 millimetres. Alternatively or in addition, a peripheral wall of the first tubular portion may have a thickness of less than about 3.0 millimetres, preferably less than about 2.5 millimetres or less than about 2 millimetres.

[0084] A peripheral wall of the first tubular portion may have a thickness of between about 0.5 millimetres and 3.0 millimetres, preferably between about 1.0 millimetre and 2.5 millimetres, and more preferably between about 1 .0 millimetre and 2.0 millimetres. In a preferred example, a peripheral wall of the first tubular portion may have a thickness of about 1.0 millimetres.

[0085] The first tubular portion of the tubular element may have a length of at least about 3 millimetres, preferably at least about 4 millimetres and more preferably at least about 5 millimetres. The first tubular portion of the tubular element may have a length of less than about 10 millimetres, preferably less than about 8 millimetres and more preferably less than about 7 millimetres.

[0086] The first tubular portion of the tubular element may have a length between about 3 millimetres and about 10 millimetres, preferably between about 4 millimetres and 8 millimetres, and more preferably between about 5 millimetres and 7 millimetres. In a preferred example, the first tubular portion of the tubular element may have a length of about 6 millimetres.

[0087] The second tubular portion of the tubular element may have an external diameter of at least about 5.0 millimetres, preferably at least about 6.0 millimetres, and more preferably at least about 7.0 millimetres. Alternatively or in addition, the second tubular portion of the tubular element may have an external diameter of less than about 10.0 millimetres, preferably less than about 9.0 millimetres, and more preferably less than about 8.0 millimetres.

[0088] The second tubular portion of the tubular element may have an external diameter between about 5.0 millimetres and about 10.0 millimetres, preferably between about 6.0 millimetres and about 9.0 millimetres, and more preferably between about 6.5 millimetres and 8.0 millimetres. In a preferred example, the second tubular portion of the tubular element may have an external diameter of about 7.0 millimetres.

[0089] A peripheral wall of the second tubular portion may have a thickness of at least 0.5 millimetres, preferably at least about 1.0 millimetre, and more preferably at least about 1.5 millimetres. Alternatively or in addition, a peripheral wall of the second tubular portion may have a thickness of less than about 3.5 millimetres, preferably less than about 3.0 millimetres, and more preferably less than about 2.5 millimetres.

[0090] A peripheral wall of the second tubular portion may have a thickness between about 0.5 millimetres and 3.5 millimetres, preferably between about 1.0 millimetre and 3.0 millimetres, and more preferably between about 1.5 millimetres and 2.5 millimetres. In a preferred example, a peripheral wall of the second tubular portion may have a thickness of about 2.0 millimetres.

[0091] The second tubular portion of the tubular element may have a length of at least about 6 millimetres, preferably at least about 7 millimetres and more preferably at least about 8 millimetres. The second tubular portion of the tubular element may have a length of less than about 12 millimetres, preferably less than about 11 millimetres and more preferably less than about 10 millimetres.

[0092] The second tubular portion of the tubular element may have a length between about 6 millimetres and about 12 millimetres, preferably between about 7 millimetres and 11 millimetres, and more preferably between about 8 millimetres and 10 millimetres. In a preferred example, the second tubular portion of the tubular element may have a length of about 9 millimetres.

[0093] An internal diameter of the tubular element may be less than an external diameter of the capsule. Advantageously, this helps to prevent the capsule from passing through the tubular element, that is, through the internal cavity in the tubular element.

[0094] The internal diameter of the tubular element may be at least 1 millimetre less than an external diameter of the capsule. Optionally, the internal diameter of the tubular element may be at least 2 millimetres less than an external diameter of the capsule. Further optionally, the internal diameter of the tubular element may be at least 3 millimetres less than an external diameter of the capsule.

[0095] The internal diameter of the tubular element may be uniform over the whole length of the tubular element. The tubular element may have an internal diameter of less than 4.5 millimetres, preferably less than 4.0 millimetres, and more preferably less than 3.5 millimetres.

[0096] An upstream end of the tubular element may be arranged to engage an external surface of the capsule. The tubular element may act as a retention plug or element for restricting downstream movement of the capsule. Advantageously, by restricting movement of the capsule, piercing of the capsule to free the contents of the capsule may be made easier by providing a surface to press against.

[0097] According to an example of the present disclosure, there is provided an aerosolgenerating article. The aerosol-generating article may comprise a substrate element comprising an aerosol-generating substrate. The aerosol-generating article may comprise a tubular element. The tubular element may comprise a circumferential recess formed in an end surface of the tubular element.

[0098] According to an example of the present disclosure, there is provided an aerosolgenerating article. The aerosol-generating article comprises: a substrate element comprising an aerosol-generating substrate; and a tubular element. The tubular element comprises a circumferential recess formed in an end surface of the tubular element.

[0099] Advantageously, circumferential recess or pocket may be used to hold or collect an aerosol-generating substrate or some other form of sensorial media. This can be used to impart the aerosol with aerosol-generating substrate as the aerosol flows through the tubular element. The circumferential recess or pocket can also be used to reduce the weight of the tubular element by reducing the amount of material used to form the tubular element.

[0100] The circumferential recess may comprise an aerosol-generating substrate or other form of sensorial media.

[0101] The tubular element may comprise a first circumferential recess formed in a first end surface of the tubular element. The tubular element may comprise a second circumferential recess formed in a second end surface of the tubular element.

[0102] The tubular element may be formed from a single wound sheet of web material.

[0103] The tubular element may comprise multiple wound layers of the single sheet of web material. The wound layers of the single sheet of web material may have a reduced width at the radial location of the circumferential recess compared to the overall length of the tubular element.

[0104] The sheet of web material may comprise one or more of paper, cardboard, acetate tow or polylactic acid (PLA).

[0105] The circumferential recess may have a depth or extend a distance into the tubular element. The depth or distance may correspond to up to 5 percent of the overall length of the tubular element, optionally up to 10 percent of the overall length of the tubular element, optionally up to 15 percent of the overall length of the tubular element, and further optionally up to 20 percent of the overall length of the tubular element.

[0106] The circumferential recess may have any suitable longitudinal cross-sectional shape. In one example, the circumferential recess may have a rectangular longitudinal cross- sectional shape. In another example, the circumferential recess may have a tapered or triangular longitudinal cross-sectional shape.

[0107] Features described in relation to one of the above examples may equally be applied to other examples of the present disclosure.

[0108] The invention is defined in the claims. However, below there is provided a non- exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0109] Example Ex1 : A method of manufacturing a tubular element for an aerosol-generating article, the tubular element having a first tubular portion and a second tubular portion, the method comprising: providing a sheet of web material having a first sheet portion corresponding to the first tubular portion and a second sheet portion corresponding to the second tubular portion; and winding the sheet of web material about the winding axis to form the tubular element.

[0110] Example Ex2: A method according to Example Ex1 , further comprising cutting a cutout from an edge of the sheet of web material to form a discontinuous edge, the cutout being cut from the first sheet portion or the second sheet portion such that the dimensions of the first and second sheet portions are different in a direction substantially perpendicular to a winding axis, the discontinuous edge being substantially parallel to the winding axis.

[0111] Example Ex3: A method according to Example Ex1 or Ex2, wherein the sheet of web material comprises a polygon having at least one corner that subtends an internal angle of 270 degrees.

[0112] Example Ex4: A method according to any preceding example, wherein the sheet comprises a plurality of first and second portions, and wherein winding the sheet forms a tubular subassembly comprising a plurality of joined tubular elements.

[0113] Example Ex5: A method according to Example Ex4, wherein the sheet comprises double-length first sheet portions and double-length second sheet portions such that the tubular subassembly comprises symmetrical pairs of tubular elements.

[0114] Example Ex6: A method according to Example Ex4 or Ex5, further comprising cutting the tubular subassembly to separate individual tubular elements.

[0115] Example Ex7: A method according to any preceding example, wherein the sheet has a continuous edge opposite the discontinuous edge.

[0116] Example Ex8: A method according to Example Ex7, wherein the sheet is wound starting from the discontinuous edge to form a tubular element having a first tubular portion with a first internal diameter and a second tubular portion with a second internal diameter, the first internal diameter being different to the second internal diameter.

[0117] Example Ex9: A method according to Example Ex8, wherein the sheet is wound around a central mandrel having a longitudinal axis that extends along the winding axis, the central mandrel having a plurality of winding sections arranged along its longitudinal axis, wherein the winding sections have external diameters corresponding to the first and second internal diameters of the first and second tubular portions respectively.

[0118] Example Ex10: A method according to Example Ex9, wherein the winding sections can be assembled to, and disassembled from, the mandrel.

[0119] Example Ex11 : A method according to Example Ex7, wherein the sheet is wound starting from the continuous edge to form a tubular element having a first tubular portion with a first external diameter and a second tubular portion with a second external diameter, the first external diameter being different to the second external diameter.

[0120] Example Ex12: A method according to Example Ex8, wherein the sheet is wound around a central mandrel having a longitudinal axis that extends along the winding axis, the central mandrel having a substantially uniform diameter along its longitudinal axis.

[0121] Example Ex13: A method according to any preceding example, wherein the discontinuous edge comprises a first discontinuous edge and the tubular element comprises a third tubular portion, the method comprising: providing a sheet of web material having a third sheet portion corresponding to the third tubular portion; cutting a cutout from an edge of the sheet of web material opposite the first continuous edge to form a second discontinuous edge, the cutout being cut from the third sheet portion.

[0122] Example Ex14: A method according to Example Ex13, the method further comprising winding the sheet starting from the first discontinuous edge to form a tubular element having different first and second internal diameters respectively and the third tubular portion has a different external diameter to the first and second tubular portions.

[0123] Example Ex15: A method according to Example Ex13, the method further comprising winding the sheet starting from the second discontinuous edge to form a tubular element having different first and second external diameters respectively and the third tubular portion has a different internal diameter to the first and second tubular portions.

[0124] Example Ex16: A method according to any preceding example, further comprising applying an adhesive to the sheet of web material prior to winding.

[0125] Example Ex17: A method according to Example Ex16, wherein the glue or adhesive is applied on an upper surface of the sheet.

[0126] Example Ex18: A method according to Example Ex16, wherein the glue or adhesive is applied on a lower surface of the sheet.

[0127] Example Ex19: A method according to any of Examples Ex16 to Ex18, wherein the glue or adhesive is applied over an entire surface of the sheet.

[0128] Example Ex20: A method according to any of Examples Ex16 to Ex18, wherein the glue or adhesive may be applied to part of a surface of the sheet.

[0129] Example Ex21 : A method according to any of Examples Ex16 to Ex20, further comprising applying heat to dry the glue or adhesive following winding.

[0130] Example Ex22: A method according to any preceding example, further comprising pressing an external surface of the sheet during winding using peripheral rollers or wheels.

[0131] Example Ex23: A method according to any preceding example, wherein the sheet of web material has a thickness between 0.05 millimetres and 0.2 millimetres.

[0132] Example Ex24: A method according to Example Ex23, wherein the sheet of web material has a thickness between 0.07 millimetres and 0.12 millimetres. Example Ex25: A method according to Example Ex24, wherein the sheet of web material has a thickness between 0.08 millimetres and 0.10 millimetres.

[0133] Example Ex26: A method according to Example Ex25, wherein the sheet of web material has a thickness of about 0.09 millimetres.

[0134] Example Ex27: A method according to any of Examples Ex16 to Ex26, wherein the glue or adhesive has a thickness between 2 micrometres and 10 micrometres.

[0135] Example Ex28: A method according to Example Ex27, wherein the glue or adhesive has a thickness between 3 micrometres and 8 micrometres.

[0136] Example Ex29: A method according to Example Ex28, wherein the glue or adhesive has a thickness between 4 micrometres and 6 micrometres.

[0137] Example Ex30: A method according to Example Ex29, wherein the glue or adhesive has a thickness of about 5 micrometres.

[0138] Example Ex31 : An aerosol-generating article comprising: a substrate element comprising an aerosol-generating substrate; and a tubular element comprising first and second tubular portions.

[0139] Example Ex32: An aerosol-generating article according to Example Ex31 , wherein the tubular element comprises integral first and second tubular portions.

[0140] Example Ex33: An aerosol-generating article according to Example Ex31 or Ex32, wherein the first tubular portion and second tubular portion each constitute at least 10 percent of the length of the tubular element.

[0141] Example Ex34: An aerosol-generating article according to any of Examples Ex31 to Ex33, wherein the first tubular portion has a first internal diameter and the second tubular portion has a second internal diameter, the first internal diameter being different to the second internal diameter.

[0142] Example Ex35: An aerosol-generating article according to any of Examples Ex31 to Ex33, wherein the first tubular portion has a first external diameter and the second tubular portion has a second external diameter, the first external diameter being different to the second external diameter.

[0143] Example Ex36: An aerosol-generating article according to Example Ex34, wherein the second internal diameter is greater than the first internal diameter.

[0144] Example Ex37: An aerosol-generating article according to Example Ex36, wherein a ratio of the second internal diameter to the first internal diameter is between 1.2 and 1 .8.

[0145] Example Ex38: An aerosol-generating article according Example Ex36 or Ex37, wherein the first tubular portion comprises an inner tube segment and a first part of an outer tube segment arranged around the inner tube segment, the first internal diameter being the internal diameter of the inner tube segment. Example Ex39: An aerosol-generating article according to Example Ex38, wherein the second tubular portion comprises a second part of the outer tube segment that extends beyond an end of the inner tube segment in a longitudinal direction of the tubular element, the second internal diameter being the internal diameter of the second part of the outer tube segment.

[0146] Example Ex40: An aerosol-generating article according to Example Ex35, wherein the first and second tubular portions have different first and second external diameters respectively.

[0147] Example Ex41 : An aerosol-generating article according to Example Ex40, wherein the substrate element comprises a capsule containing an aerosol-generating substrate.

[0148] Example Ex42: An aerosol-generating article according to Example Ex40 or Ex41 , wherein the first external diameter is less than the second external diameter.

[0149] Example Ex43: An aerosol-generating article according to any of Examples Ex40 to Ex42, wherein a ratio between the second external diameter and the first external diameter is between 1 .2 and 1 .8.

[0150] Example Ex44: An aerosol-generating article according to Examples Ex42 or Ex43, wherein the first tubular portion comprises a first part of an inner tube segment, the first external diameter being the external diameter of the first part of the inner tube segment.

[0151] Example Ex45: An aerosol-generating article according to Example Ex44, wherein the second tubular portion comprises a second part of the inner tube segment and an outer tube segment arranged around the second part of the inner tube segment, the second external diameter being the external diameter of the outer tube segment.

[0152] Example Ex46: An aerosol-generating article according to any of Examples Ex41 to Ex45, wherein an internal diameter of the tubular element is less than an external diameter of the capsule.

[0153] Examples will now be further described with reference to the figures in which:

[0154] Figure 1 is a schematic longitudinal cross-sectional view of an aerosol-generating article.

[0155] Figure 1 A is a schematic longitudinal cross-sectional view of the tubular element of the aerosol-generating article of Figure 1 showing this feature in more detail.

[0156] Figure 2 is a schematic longitudinal cross-sectional view of another aerosol-generating article.

[0157] Figure 2A is a schematic longitudinal cross-sectional view of the tubular element of the aerosol-generating article of Figure 2 showing this feature in more detail.

[0158] Figure 3 is flow chart of a method for manufacturing a tubular element for an aerosolgenerating article from a sheet of web material. Figure 4 is a schematic longitudinal cross-sectional view of a tubular subassembly comprising multiple tubular elements.

[0159] Figure 5 is a schematic plan view of a cut sheet of web material for forming a tubular subassembly comprising six tubular elements having different external diameters.

[0160] Figures 6A to 6C show a method step for winding the cut sheet of web material of Figure 5 to form the tubular subassembly.

[0161] Figure 7A shows a perspective view of a cutting step for cutting the tubular subassembly of Figure 6C.

[0162] Figure 7B is a schematic longitudinal cross-sectional view of the tubular subassembly of Figure 6C showing the locations at which the subassembly is cut.

[0163] Figure 8 is a schematic plan view of cut sheet of web material for forming a tubular subassembly comprising six tubular elements having different internal diameters.

[0164] Figures 9A and 9B show a method step for winding the cut sheet of web material of Figure 8 to form the tubular subassembly.

[0165] Figures 10A and 10B are schematic longitudinal cross-sectional views of a mandrel comprising a plurality of winding sections for winding a tubular subassembly showing the mandrel in a disassembled and assembled state respectively.

[0166] Figure 10C is a schematic longitudinal cross-sectional view showing a tubular subassembly wound around the assembled mandrel of Figure 10B.

[0167] Figures 11 A and 11 B are schematic longitudinal cross-sectional views of another mandrel comprising a plurality of winding sections for winding a tubular subassembly showing the mandrel in a disassembled and assembled state respectively.

[0168] Figure 11 C is a schematic longitudinal cross-sectional view showing a tubular subassembly wound around the assembled mandrel of Figure 11 B.

[0169] Figure 12 shows a perspective view of a cutting step for cutting the tubular subassemblies of Figure 10C and 11C.

[0170] Figures 13A to 13D show a series of steps for ejecting tubular elements having different internal diameters from a mandrel.

[0171] Figure 14A is a schematic longitudinal cross-sectional view of another tubular element for an aerosol-generating article.

[0172] Figure 14B shows a cut-sheet for forming the tubular element of Figure 14A.

[0173] Figure 15A is schematic longitudinal cross-sectional view of another tubular element for an aerosol-generating article.

[0174] Figure 15B is a schematic plan view of a cut-sheet for forming the tubular element of Figure 15A.

[0175] Figure 16 is a schematic perspective view of a gluing station for gluing the cut-sheet of Figure 15B.

[0176] Figures 17A, 17B and 17D are schematic perspective views of a winding station showing a sequence of steps for winding the cut-sheet of Figure 15B.

[0177] Figures 17C and 17E show the peripheral roller section of the winding stations of Figures 17B and 17D respectively in more detail.

[0178] Figure 18A is a schematic perspective view of a gluing and winding station for gluing and winding another cut-sheet.

[0179] Figure 18B shows the peripheral roller section of the winding station of Figures 18A in more detail.

[0180] Figure 19A is a schematic longitudinal cross-sectional view of another tubular element for an aerosol-generating article.

[0181] Figure 19B shows a cut-sheet for forming the tubular element of Figure 19A.

[0182] Figure 20A is a schematic longitudinal cross-sectional view of another tubular element for an aerosol-generating article.

[0183] Figure 20B shows a cut-sheet for forming the tubular element of Figure 20A.

[0184] Figure 21 A is a schematic longitudinal cross-sectional view of another tubular element for an aerosol-generating article.

[0185] Figure 21 B shows a cut-sheet for forming the tubular element of Figure 21A.

[0186] Referring to Figure 1 , there is shown an aerosol-generating article 1 comprising a plurality of elements assembled in the form of a rod. The aerosol-generating article 1 comprises a substrate element 2 containing aerosol-generating substrate and a downstream section 4 at a location downstream of the substrate element 2. Further, the aerosol-generating article 1 comprises an upstream section 6 at a location upstream of the substrate element 2. The aerosol-generating article 1 extends from an upstream or distal end 8 to a downstream or mouth end 10. The aerosol-generating article has an overall length of about 45 millimetres.

[0187] The downstream section 4 comprises a tubular element 12 located immediately downstream of the substrate element 2, the tubular element 12 being in longitudinal alignment with the substrate element 2. In the example of Figure 1 , the upstream end of the tubular element 12 abuts the downstream end of the substrate element 2. The tubular element 12 comprises a first tubular portion 14 and a second tubular portion 16, the second tubular portion 16 being downstream of the first tubular portion 14. The tubular element 12 is formed as a unitary element, that is, as a single piece. The first 14 and second 16 tubular portions each forming part of the overall tubular element.

[0188] The first tubular portion 14 of the tubular element 12 defines an internal cavity 18 that extends all the way from an upstream end 20 of the first tubular portion 14 to a downstream end 22 of the first tubular portion 14. The internal cavity 18 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 18. Therefore, the first tubular portion 14 does not substantially contribute to the overall RTD of the aerosolgenerating article 1. In more detail, the RTD of the first tubular portion 14 is substantially 0 millimetres H2O. The first tubular portion 14 of the tubular element 12 is configured to act as a spacer or support element for the aerosol-generating article 1.

[0189] The second tubular portion 16 of the tubular element 12 defines an internal cavity 24 that extends all the way from an upstream end 22 of the second tubular portion 16 to a downstream end 26 of the second tubular portion 16. The internal cavity 24 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 24. The second tubular portion does not substantially contribute to the overall RTD of the aerosolgenerating article 10. In more detail, the RTD of the second tubular portion 16 is substantially 0 millimetres H2O. The second tubular portion 16 of the tubular element 12 is configured to act as an aerosol-cooling element for the aerosol-generating article 1 .

[0190] The aerosol-generating article 1 further comprises a ventilation zone 28 provided at a location along the second tubular portion 16 of the tubular element 12. In more detail, the ventilation zone 28 is provided at about 2 millimetres from the upstream end 22 of the second tubular portion 16. The ventilation zone 28 comprises a circumferential ring of ventilation holes extending through the wall of the second tubular portion 16. Air may be drawn through the ventilation holes and through the second tubular portion 16 to achieve cooling of the stream of aerosol generated upon heating of the substrate element 2. A ventilation level of the aerosol-generating article 1 is about 25 percent.

[0191] In the example of Figure 1 , the downstream section 4 further comprises a mouthpiece element 30 at a location downstream of the tubular element 12. In more detail, the mouthpiece element 30 is positioned immediately downstream of the second tubular portion 16 of the tubular element 12. An upstream end of the mouthpiece element 30 abuts the downstream end 26 of the second tubular portion 16 of the tubular element 12. The mouthpiece element 30 is provided in the form of a cylindrical plug of low-density cellulose acetate. The mouthpiece element 30 further comprises a wrapper or plug wrap 35 circumscribing the cellulose acetate plug. The mouthpiece element 30 has a length of about 12 millimetres and an external diameter of about 7.1 millimetres.

[0192] The substrate element 2 comprises an aerosol-generating substrate of one of the types described above. The substrate element 2 is in the form of a rod comprising the aerosolgenerating substrate. The aerosol-generating substate may substantially define the structure and dimensions of the rod 2. The rod 2 may further comprise a wrapper (not shown) circumscribing the aerosol-generating substrate. The substrate element 2 has an external diameter of about 7.1 millimetres and a length of about 12 millimetres. However, it will be appreciated that these dimensions can vary. For example, in another aerosol-generating article the substrate element 2 may have a length of about 11 millimetres.

[0193] The aerosol-generating article 1 further comprises an elongate susceptor element 32 within the substrate element 2. In more detail, the susceptor element 32 is arranged substantially longitudinally within the aerosol-generating substrate, such as to be approximately parallel to the longitudinal direction of the rod-shaped substrate element 2. The susceptor element 32 is positioned in a radially central position within the substrate element 2 and extends effectively along the longitudinal axis of the substrate element 2. The susceptor element 32 extends all the way from an upstream end to a downstream end of the substrate element 2. In effect, the susceptor element 32 has substantially the same length as the substrate element 2. In the example of Figure 1 , the susceptor element 32 is provided in the form of a strip and has a length of about 12 millimetres, a thickness of about 60 micrometres, and a width of about 4 millimetres.

[0194] The upstream section 6 comprises an upstream element 34 located immediately upstream of the substrate element 2, the upstream element 34 being in longitudinal alignment with the substrate element 2. In the example of Figure 1 , the downstream end of the upstream element 34 abuts the upstream end of the substrate element 2. This advantageously prevents the susceptor element 44 from being dislodged. Further, this ensures that the consumer cannot accidentally contact the heated susceptor element 34 after use. The upstream element 34 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper (not shown). The upstream element 34 has a length of about 5 millimetres.

[0195] The aerosol-generating article 1 further comprises a wrapper 36 circumscribing the upstream element 34, the substrate element 2 and the tubular element 12. The wrapper 36 extends from the upstream or distal end 8 of the aerosol-generating article 1 to the downstream end 26 of the second tubular portion 16. The ventilation holes of the ventilation zone 28 extend through the wrapper 36 to communicate with the ventilation holes in the tubular element 12. The mouthpiece element 30 is joined to the aerosol-generating article 1 by a tipping paper 37 that circumscribes the mouthpiece element 30 and a part of the downstream end of the second tubular portion 16 that is wrapped in wrapper 36.

[0196] Figure 1 A shows the tubular element 12 of the aerosol-generating article 1 of Figure 1 in more detail. The first tubular portion 14 has a length L1 of about 8 millimetres and the second tubular portion 16 has a length L2 of about 8 millimetres. Therefore, the first tubular portion 14 and second tubular portion 16 each constitute about 50 percent of the length of the tubular element. However, it will be appreciated that these lengths, and their relative percentages, can vary. For example, in another aerosol-generating article the second tubular portion may have a length of 9 millimetres. The first tubular portion 14 and second tubular portion 16 have the same external diameter Dext of about 7.1 millimetres, which is constant over the whole length (L1 + L2) of the tubular element 12. The first tubular portion 14 and second tubular portion 16 have different internal diameters. The first tubular portion 14 has a first internal diameter D1int of about 3.3 millimetres. Thus, a thickness of a peripheral wall of the first tubular portion 14 is about 1.9 millimetres. The second tubular portion 16 has a second internal diameter D2jnt of about 5.0 millimetres. Thus, a thickness of a peripheral wall of the second tubular portion 16 is about 1.05 millimetres. The first internal diameter D1int of the first tubular portion 14 is uniform over the length L1 of the first tubular portion 14 and the second internal diameter D2jnt of the second tubular portion 16 is uniform over the length L2 of the second tubular portion 16. A ratio between the second internal diameter D2jnt of the second tubular portion 16 and the first internal diameter D1int of the first tubular portion 14 is about 1.52.

[0197] The tubular element 12 is formed from a single wound sheet of web material. The sheet is wound over itself so that the tubular element 12 comprises multiple wound layers 38 of the single sheet of web material. The first 14 and second 16 tubular portions each having a different number of wound layers 38 to provide the different thicknesses of their respective peripheral walls. Forming the tubular element 12 from a single wound sheet of web material automatically ensures that the first 14 and second 16 tubular portions are axially aligned. It also results in a unitary tubular element, that is, a tubular element formed as a single piece, which alleviates any difficulties in positioning the first 14 and second 16 tubular portions relative to each other compared to forming the first 14 and second 16 tubular portions as separate elements.

[0198] Figure 2 is a schematic longitudinal cross-sectional view of another aerosol-generating article 100. The aerosol-generating article 100 is an inhaler article such as a dry powder inhaler. The aerosol-generating article 100 comprises a tubular body 102 having a partially- closed distal or upstream end 104 and a partially-closed downstream or mouth end 106. An upstream opening 108 is formed in the upstream end 104 of the tubular body 102 and a downstream opening 110 is formed in the mouth end 106 of the tubular body 102. The upstream opening 108 acts as an air inlet and the downstream opening 110 acts as an air outlet. An airflow pathway extends between the upstream opening 108 and the downstream opening 110 and passes through an interior cavity 107 of the tubular body 102. An upstream portion 109 of the interior cavity of the tubular body 102 near the upstream end 104 houses a capsule 111 containing nicotine particles.

[0199] The partially closed upstream end 104 of the tubular body 102 prevents the capsule 111 from falling out of the upstream end 104 of the tubular body 102. The diameter of the capsule 111 is larger than the diameter of the upstream opening 108 and therefore cannot pass through the upstream opening 108. A tubular element 112 is provided downstream of the capsule 111. The tubular element 112 is fixed to an internal surface of the tubular body 102 and acts as a retention plug for restricting downstream movement of the capsule 111 to maintain the capsule 111 in an upstream region of the tubular body 102.

[0200] The tubular element 112 comprises a first tubular portion 114 and a second tubular portion 116, the second tubular portion 116 being downstream of the first tubular portion 114. The tubular element 112 is formed as a unitary element, that is, as a single piece. The first 114 and second 116 tubular portions each forming part of the overall tubular element 112.

[0201] The first tubular portion 114 has a first external diameter that is less than an internal diameter of the tubular body 102. The second tubular portion 116 has a second external diameter that is substantially the same as the internal diameter of the tubular body 102. Thus, the first external diameter of the first tubular portion 114 is different to the second external diameter of the second tubular portion 116, in particular, the first external diameter is less than the second external diameter. The tubular element is fixed to the internal surface of the tubular body 102 in the region of the second tubular portion 116.

[0202] The tubular element 112 defines an internal cavity 118 that extends all the way from an upstream end of the tubular element 112 to a downstream end of the tubular element 112. The internal cavity 118 is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity 118. The internal diameter of the internal cavity 118 is less than an external diameter of the capsule 111 and therefore the capsule is prevented from passing through the tubular element 112.

[0203] In use, a consumer pierces the capsule 111 via the upstream opening 108 using an external piercing tool 120 (shown in dashed outline in Figure 2). The piercing tool 120 is pushed through the upstream opening 108 and into the capsule 111 to create a hole 122 in the capsule 111 via which nicotine particles can exit the capsule 111 . Substantial downstream movement of the capsule 111 is limited by the tubular element 112. An upstream end of the tubular element 112 comes into abutting contact with the capsule 111 during piercing and holds the capsule 111 in position to allow for easier piercing.

[0204] When a consumer inhales or draws on the mouth end 106 of the aerosol-generating article 100, air is drawn in through the upstream opening 108 and through the upstream portion 109 of the internal cavity 107 of the tubular body 102 housing the capsule 111. Nicotines particles exit the capsule and are entrained in the airflow through the tubular body 102. The airflow laden with nicotine particles passes through the internal cavity 118 of the tubular element 112 and enters a downstream portion 124 of the internal cavity 107 of the tubular body 102. The internal diameter of the downstream portion 124 of the internal cavity 107 of the tubular body 102 is larger than the internal diameter of the internal cavity 118 of the tubular element 112. The expansion in cross-section of the airflow pathway as air passes from the tubular element 112 into the downstream portion 124 of the internal cavity 107 of the tubular body 102 causes a swirling effect which helps to mix the nicotine particles with the airflow before being drawn into the consumer’s mouth via the downstream opening 110.

[0205] The smaller first external diameter of the first tubular portion 114 of the tubular element 112 defines an annular space 126 between an external surface of the first tubular portion 114 and an internal surface of the tubular body 102. The annular space 126 defines a gutter or well that collects excess nicotine particles that are released from the capsule 111 but are not entrained in the airflow when a consumer draws on the aerosol-generating article 100. The annular space 126 also collects nicotine particles that are released from the capsule when the aerosol-generating article 100 is moved around between consumer inhalations. The annular space 126 created by the tubular element 112 acts as a barrier that reduces the likelihood of the nicotine particles leaking from the aerosol-generating article 100 between consumer inhalations or between uses of the aerosol-generating article 100.

[0206] Figure 2A shows the tubular element 112 of the aerosol-generating article 100 of Figure 2 in more detail. The first tubular portion 114 has a length L1 of about 6 millimetres and the second tubular portion 116 has a length L2 of about 9 millimetres. Therefore, the first tubular portion 114 and second tubular portion 116 each constitute about 50 percent of the length of the tubular element. However, it will be appreciated that these lengths, and their relative percentages, can vary.

[0207] The first tubular portion 114 and second tubular portion 116 have the same internal diameter Dint of about 3.0 millimetres, which is constant over the whole length (L1 + L2) of the tubular element 112. The first tubular portion 114 and second tubular portion 116 have different external diameters. The first tubular portion 114 has a first external diameter D1extof about 5.0 millimetres. Thus, a thickness of a peripheral wall of the first tubular portion 114 is about 1.0 millimetres. The second tubular portion 116 has a second external diameter D2ext of about 7.0 millimetres. Thus, a thickness of a peripheral wall of the second tubular portion 16 is about 2.0 millimetres. The first external diameter D1extof the first tubular portion 114 is uniform over the length L1 of the first tubular portion 114 and the second external diameter D2extof the second tubular portion 116 is uniform over the length L2 of the second tubular portion 116. A ratio between the second external diameter D2extof the second tubular portion 116 and the first external diameter D1extof the first tubular portion 114 is about 1.4.

[0208] The tubular element 112 is formed from a single wound sheet of web material. The sheet is wound over itself so that the tubular element 112 comprises multiple wound layers 138 of the single sheet of web material. The first 114 and second 116 tubular portions each having a different number of wound layers 138 to provide the different thicknesses of their respective peripheral walls. Forming the tubular element 112 from a single wound sheet of web material automatically ensures that the first 114 and second 116 tubular portions are axially aligned. It also results in a unitary tubular element, that is, a tubular element formed as a single piece, which alleviates any difficulties in positioning the first 114 and second 116 tubular portions relative to each other compared to forming the first 114 and second 116 tubular portions as separate elements.

[0209] Figure 3 shows a flow chart of a method for manufacturing a tubular element for an aerosol-generating article, for example, the tubular element of Figures 1Aand 2A. The method manufactures the tubular element from a single wound sheet of web material. The sheet of web material has a first sheet portion corresponding to the first tubular portion of the tubular element and a second sheet portion corresponding to the second tubular portion of the tubular element. The sheet of web material may be dimensioned so that multiple tubular elements can be made from a single sheet of web material.

[0210] In a first step S1 , the method comprises sheet cutting, in which a cutout is cut from an edge of the sheet of web material to form a discontinuous edge. The cutout is cut from the first sheet portion or the second sheet portion such that the dimensions of the first and second sheet portions are different in a direction substantially perpendicular to a winding axis. The discontinuous edge is arranged substantially parallel to the winding axis.

[0211] In a second step S2, the method comprises gluing, in which the cut sheet is coated with a glue or adhesive to hold multiple layers of the wound sheet of web material together after winding.

[0212] In a third step S3, the method comprises winding, in which the cut and glued sheet is wound around a rotating central pin or mandrel to create the tubular element. The sheet may be pressed on the pin or mandrel by peripheral rollers or wheels.

[0213] In a fourth step S4, the method comprises a drying step, in which the glue or adhesive is cured or set. This step is optional and may be used to speed up the manufacturing process. Such a drying step could be conducted by providing a heat source such as a heated bar close to the wound sheet of web material.

[0214] In the case where multiple tubular elements are made from a single sheet of web material, the method may comprise a fifth step S5 of tube cutting, in which individual tubular elements are cut to length and separate from the wound sheet of web material. This may be done by multiple knives or blades spaced apart by the length of an individual tubular element. The knives or blades are configured to cut transversely to the winding axis of the central pin or mandrel.

[0215] In a final sixth step S6, the method comprises ejecting the tubular elements, that is, removing the tubular elements from the central pin or mandrel. In the case where the tubular element has first and second tubular portions with different internal diameters, the central pin or mandrel about which the sheet of web material is wound may comprise a plurality of winding sections arranged along a longitudinal axis of the pin or mandrel, as described further below. The plurality of winding sections may be capable of being disassembled and reassembled and have external diameters corresponding to the internal diameters of the tubular element.

[0216] Each of the above method steps will be discussed in more detail below in relation to different examples of tubular elements.

[0217] Figure 4 shows a schematic longitudinal cross-sectional view of a tubular subassembly 200 comprising three tubular elements A, B and C formed using the methods described herein. The tubular subassembly is formed as a single piece from a single sheet of web material and is shown prior to separation of individual tubular elements. Tubular element A is similar to the tubular element 112 in Figure 2A and comprises first A1 and second A2 tubular portions having different external diameters and a constant internal diameter. Tubular element B is similar to the tubular element 12 of Figure 1A and comprises first B1 and second B2 tubular portions having different internal diameters and a constant external diameter. Tubular element C comprises first C1 , second C2 and third C3 tubular portions. The first C1 and second C2 tubular portions have different first and second external diameters respectively and the third tubular portion C3 has a different internal diameter to the first C1 and second C2 tubular portions. The external diameter of the third tubular portion is the same as the external diameter of the second tubular portion C2. The dotted lines in Figure 4 show the locations at which the tubular subassembly 200 is cut to separate individual tubular elements.

[0218] Figure 4 is intended to be merely illustrative of the types of tubular elements that can be formed using the methods described herein. Although the three different types of tubular element in Figure 4 could be formed around a single central mandrel having winding sections of different external diameters, it will be appreciated that a manufacturing station will generally be devoted to producing just a single type of tubular element.

[0219] Figures 5 to 7B show various steps of a method for forming tubular elements having different external diameters and a constant internal diameter. The method will create six tubular elements each of length Lp having two different external diameters; a first external diameter D1 over a length L1 of a first tubular portion and a second external diameter D2 over a length L2 of a second tubular portion. In this example, D2 is greater than D1. The length of the tubular element Lp is equal to L1+L2 and the tubular elements have an internal diameter d. The thickness of the sheet of web material used to form the tubular elements is Ts and the thickness of the layer of glue between successive layers of the web material is Tg.

[0220] Figure 5 is a schematic plan view of a cut sheet 300 of web material for forming a tubular subassembly comprising the six tubular elements having different external diameters. It will be appreciated that the cut sheet 300 is not drawn to scale. The portions of the cut sheet 300 corresponding to each of the tubular elements, that is, the portions of the cut sheet 300 having width Lp, each has a first sheet portion 300a having a width L1 corresponding to a length of a first tubular portion of a tubular element and a second sheet portion 300b having a width L2 corresponding to a length of a second tubular portion of a tubular element. The cut sheet 300 of Figure 5 is configured to produce three symmetrical pairs of tubular elements, each symmetrical pair being arranged back-to-back. That is, in each symmetrical pair the second sheet portions 300b are arranged adjacent each other. In Figure 5, La is the length of each symmetrical pair of tubular elements and is equal to 2Lp. Ls is the total width of the sheet and is equal to 3La.

[0221] One side of the cut sheet 300 has a continuous edge 302 and an opposing side of the cut sheet 300 has a discontinuous edge 304. A cut-out 306 has been cut from each first sheet portion 300a of the cut sheet 300 to form the discontinuous edge 304. The continuous edge 302 does not have any cut-outs and therefore forms a straight continuous edge of the cutsheet 300. To form tubular elements having different external diameters and a constant internal diameter, the continuous edge 302 of the cut sheet 300 will be fed on to a rotating mandrel first such that the cut sheet 300 starts to be wound around the mandrel by the continuous edge 302. The discontinuous edge 304 having cut-outs 306 will be wound last and the second sheet portions 300b will provide the extra thicknesses for the larger external diameter D2. The cut sheet can be cut by various known techniques, including, for example, paper cutting machines.

[0222] The cut sheet 300 is a polygon in which all internal angles are either 90 degrees or 270 degrees. The cut-outs 306 provide at least one internal angle of 270 degrees so that the cut sheet 300 is not a rectangle or a square. The cut-outs 306 in the cut sheet 300 result in the first 300a and second 300b sheet portions having different dimensions in a direction substantially perpendicular to a winding axis. The winding axis is defined by the longitudinal axis of the mandrel. The cut sheet 300 is wound so that the continuous edge 302 and discontinuous edge 304 are substantially parallel to the winding axis. As a result of the cutouts 306, the first sheet portions 300a have a length H1 and the second sheet portions 300b have a length H1 + H2 in a direction perpendicular to the winding axis or perpendicular to the continuous 302 and discontinuous 304 edges. Lengths H1 and H2 determine the thickness of the peripheral walls of the tubular elements and the difference between H1 and H1 + H2 results in the tubular element having different external diameters in the first and second tubular portions.

[0223] The dimensions H 1 and H2 can be determined as follows. If N 1 is the number of layers of the sheet of web material needed for the first external diameter D1 of a first tubular portion of a tubular element, then N1 can be expressed according to the variables discussed above as:

[0224] Rearranging for N1 gives: Equation (1)

[0225] H1 can then be calculated as follows:

[0226] Hl —:nd + ir(d 4- 2(Ts 4- Tg)) 4- TT (ci 4- 4(Ts + Tg)) 4- ... 4- (d 4- 2(N1 — l)(Ts + Tg))

[0227] Equation (2)

[0228] Similar calculations to those above can also be used to determine N2, which is the number of layers of the sheet of web material needed for the second external diameter D2 of a second tubular portion of a tubular element and H2.

[0229] In the gluing step of the manufacturing method, the glue can be applied on the cut sheet 300 by nozzles or glue roller(s), depending on the orientation of the paper relataive to the rotating central pin or mandrel. For a manufacturing method where the sheets are fed to the bottom of the mandrel, the top surface of the cut sheet should be glued and so nozzles are a good solution. For a manufacturing method where the sheets are fed to the top of the mandrel, the bottom surface of the sheets should be glued and so glue roller(s) are a good solution.

[0230] Two types of glue have been found to be particularly advantageous for gluing the cut sheet 300. Firstly, a fast action glue, like ethylene-vinyl acetate (EVA) or poly (ethylene-vinyl acetate) (PEVA), which type of glue is commonly used for paper as it bonds well with cellulosic material, to quickly fix the layers of web material making up the tubular element. Preferably, this glue should undergo a drying step to help it solidify quickly. Secondly, a long-term action glue, like poly-vinyl acetate (PVA), which can be used to assure that the multi-layered structure of the tubular element is held in place over time. In particular, this type of glue can help to reduce the likelihood of the edges of the layers of the tubular element to collapsing into the central cavity over time. Both types of glue could be applied to the same cut-sheet to ensure effective bonding. Alternatively, only one of the glues could be applied. In the case of using only one glue, a fast action glue like EVA is generally selected.

[0231] It may be desirable to not apply glue to the part of the cut sheet 300 that contacts the mandrel to reduce the risk of the sheet sticking to the mandrel. In Figure 5, glue is not applied across the width of the sheet for the distance Hg from the continuous edge 302. Hg is equal to one circumference of the first layer of the sheet around the central mandrel, that is, Hg equals u.d. Glue is applied to the remainder of the cut-sheet 300.

[0232] Alternatively, glue could be also applied on those parts of the cut sheet 300 that will be in direct contact with the central pin or mandrel. This has been found to help the cut sheet 300 start to wind around the mandrel. Since the central pin or mandrel is generally formed from metal, for example, stainless steel, and the cut sheet 300 is tightly wound around it, when ejecting the resulting tubular structure, the glue will be removed from the central pin or mandrel, making it available for a new cut sheet.

[0233] Figures 6A to 6C show a method step for winding the cut sheet 300 of web material of Figure 5 to form a tubular subassembly.

[0234] Figures 6A and 6B show a perspective view and cross-sectional view respectively of the winding step in which the cut sheet 300 is wound around a rotating central pin or mandrel 330 to create a tubular subassembly 324 having different external diameters. The central mandrel 330 has a constant external diameter along its longitudinal or winding axis which corresponds to the constant internal diameter of the tubular subassembly 324. The cut sheet 300 is driven by a roller 331 to the rotating central mandrel 330. The cut sheet 300 is presented to the rotating mandrel by it continuous edge first. The longitudinal dimension of the cut-sheet 300, that is, the dimension between the continuous edge and discontinuous edge is perpendicular to the winding or longitudinal axis of the central mandrel 330. The cut sheet 300 is wound around the mandrel 330 and pressed towards the central mandrel 330 by peripheral rollers 332. This helps to wind the cut sheet 300 on the central mandrel with the desired amount of pressure. In Figures 6A and 6B, the cut sheet 300 is fed to the bottom of the central mandrel 330, although it will be appreciated that it could also be fed to the top of the central mandrel 330.

[0235] Figure 6C shows a perspective view of the tubular subassembly 324 following winding around the central mandrel 330. The tubular subassembly 324 has tubular portions with different external diameters and a constant internal diameter, which internal diameter corresponds to the external diameter of the central mandrel. Following the winding step, the wound tubular subassembly may be heated to dry or cure the glue.

[0236] Figure 7A shows a perspective view of a cutting step for cutting the tubular subassembly 324 of Figure 6C. In the example, of Figure 7A the tubular subassembly 324 is cut by circular knives 340 fixed on a rotating shaft 41 , which is moved toward the central mandrel 330 to cut and separate individual tubular elements from tubular subassembly 324. It will be appreciated that other methods of the cutting the tubular subassembly may be used.

[0237] Figure 7B is a schematic longitudinal cross-sectional view of the tubular subassembly

[0238] 324 of Figure 6C arranged on central mandrel 330. The tubular subassembly 324 is cut at the location of the cut lines 342 (shown as doted lines in Figure 7B) to produce tubular elements

[0239] 325 each having a length Lp.

[0240] An ejection step (not shown) follows the cutting step of Figures 7A and 7B, in which the tubular elements 325 are ejected from the central mandrel 330. The ejection may be performed by one or more mechanical actuators, pushing along the longitudinal axis of the central mandrel 330. Given that the internal diameter d of the tubular elements 325 is constant and smooth, all the plugs can be pushed together along one or the other direction of the central mandrel 330.

[0241] Figures 8 to 13D show various steps of a method for forming tubular elements having different internal diameters and a constant external diameter. The method will create six tubular elements each of length Lp having two different internal diameters; a first internal diameter D1 over a length L1 of a first tubular portion and a second internal diameter D2 over a length L2 of a second tubular portion. In this example, D2 is greater than D1. The length of the tubular element Lp is equal to L1+L2 and the tubular elements have an external diameter Dext. The thickness of the sheet of web material used to form the tubular elements is Ts and the thickness of the layer of glue between successive layers of the web material is Tg.

[0242] Figure 8 is a schematic plan view of a cut sheet 400 of web material for forming a tubular subassembly comprising the six tubular elements having different internal diameters. It will be appreciated that the cut sheet 400 is not drawn to scale. The portions of the cut sheet 300 corresponding to each of the tubular elements, that is, the portions of the cut sheet 300 having length Lp, each has a first sheet portion 400a having a width L1 corresponding to a length of a first tubular portion of a tubular element and a second sheet portion 400b having a width L2 corresponding to a length of a second tubular portion of a tubular element. The cut sheet 400 of Figure 8 is configured to produce three symmetrical pairs of tubular elements, each symmetrical pair being arranged back-to-back. That is, in each symmetrical pair the second sheet portions 400b are arranged adjacent each other. In Figure 8, La is the length of each symmetrical pair of tubular elements and is equal to 2Lp. Ls is the total width of the sheet and is equal to 3La.

[0243] One side of the cut sheet 400 has a continuous edge 402 and an opposing side of the cut sheet 400 has a discontinuous edge 404. A cut-out 406 has been cut from each first sheet portion 400a of the cut sheet 400 to form the discontinuous edge 404. The continuous edge 402 does not have any cut-outs and therefore forms a straight continuous edge of the cutsheet 400. To form tubular elements having different internal diameters and a constant external diameter, the discontinuous edge 404 of the cut sheet 400 will be fed on to a rotating mandrel first such that the cut sheet 400 starts to be wound around the mandrel by the discontinuous edge 404. The second sheet portions 400b of the discontinuous edge 404 will provide the extra thicknesses for the smaller internal diameter D1 . The cut sheet can be cut by various known techniques, including, for example, paper cutting machines.

[0244] The cut sheet 400 is a polygon in which all internal angles are either 90 degrees or 270 degrees. The cut-outs 406 provide at least one internal angle of 270 degrees so that the cut sheet 400 is not a rectangle or a square. The cut-outs 406 in the cut sheet 400 result in the first 400a and second 400b sheet portions having different dimensions in a direction substantially perpendicular to a winding axis. The winding axis is defined by the longitudinal axis of the mandrel. The cut sheet 400 is wound so that the continuous edge 402 and discontinuous edge 404 are substantially parallel to the winding axis. As a result of the cutouts 406, the first sheet portions 400a have a length H1 and the second sheet portions 400b have a length H1 + H2 in a direction perpendicular to the winding axis or perpendicular to the continuous 402 and discontinuous 404 edges. Lengths H1 and H2 determine the thickness of the peripheral walls of the tubular elements and the difference between H1 and H1 + H2 results in the tubular element having different internal diameters in the first and second tubular portions.

[0245] The dimensions H1 and H2 can be determined using similar equations to equations 1 and 2 above, with account being given to the fact that the tubular element in this example has different internal diameters.

[0246] In the gluing step of the manufacturing method of Figures 8 to 13D, substantially the same gluing considerations apply as apply to the manufacturing method of Figures 5 to 7B. One difference is the area in which glue is not applied to the part of the cut sheet 400 that contacts the mandrel to reduce the risk of the sheet sticking to the mandrel because in this example method the cut sheet is fed to the mandrel by its discontinuous edge 404. In Figure 8, glue is not applied in the areas of the cut-sheet 400 trailing the discontinuous edge 404 for the distance Hg from the discontinuous edge 404. Hg is equal to one circumference of the first layer of the sheet around the central mandrel, that is, Hg equals u.d. Glue is applied to the remainder of the cut-sheet 300.

[0247] Figures 9A and 9B show a method step for winding the cut sheet of web material of Figure 8 to form the tubular subassembly.

[0248] Figures 9A and 9B show perspective views of the winding step in which the cut sheet 400 is wound around a rotating central pin or mandrel 430 to create a tubular subassembly 424 having different internal diameters. The central mandrel 430 has different external diameters along its longitudinal or winding axis which correspond to the different internal diameters of the tubular subassembly 424. In particular, the central mandrel 430 has a plurality of alternating first diameter sections 430a and second diameter sections 430b arranged along it longitudinal axis. The plurality of first diameter sections 430a have a smaller external diameter than the plurality of second diameter sections 430b. The smaller external diameter of the plurality of first diameter sections 430a corresponds to the smaller internal diameters of the tubular subassembly 424. The larger external diameter of the plurality of second diameter sections 430b corresponds to the larger internal diameters of the tubular subassembly 424. The indented parts of the cut-sheet 400, that is, the first sheet portions 400a having cut-outs 406 (see Figure 8) will create the smaller diameter portions of the tubular subassembly 424.

[0249] The cut sheet 400 is driven by a roller 431 to the rotating central mandrel 430. The cut sheet 400 is presented to the rotating mandrel 430 by it discontinuous edge 404 first. The longitudinal dimension of the cut-sheet 400, that is, the dimension between the continuous edge and discontinuous edge is perpendicular to the winding or longitudinal axis of the central mandrel 430. The cut sheet 400 is wound around the mandrel 430 and, due to the different external diameters of the mandrel 430, the cut-sheet 400 is pressed towards the mandrel 430 by peripheral short rollers or wheels 433. The peripheral wheels 433 can press on the cutsheet in the regions corresponding to the first diameter sections 430a of smaller diameter, which wind the second sheets portions 400b of the cut-sheet 400 first. This helps to wind the cut sheet 400 on the central mandrel 430 with the desired amount of pressure. In Figures 9A and 9B, the cut sheet 400 is fed to the bottom of the central mandrel 430, although it will be appreciated that it could also be fed to the top of the central mandrel 430.

[0250] Following winding around the central mandrel 430, the tubular subassembly 424 has tubular portions with different internal diameters and a constant external diameter. After the winding step, the wound tubular subassembly 424 may be heated to dry or cure the glue.

[0251] Figures 10A and 10B are schematic longitudinal cross-sectional views of a mandrel 430 comprising a plurality of winding sections 434 for winding a tubular subassembly. Such a mandrel 430 can be used to form tubular elements having different internal diameters as shown, for example, in Figures 9A and 9B. Figure 10A shows the mandrel 430 in a disassembled state and Figure 10B shows the mandrel 430 in an assembled state. Each winding section 434 is configured to form a single tubular element, although, as discussed below, a winding section may be configured to form more than one tubular element. Each winding section 434 has a first diameter section 430a and a second diameter section 430b. The first diameter sections 430a have a smaller external diameter than the second diameter sections 430b, as discussed above with respect to Figure 9A. Each winding section 434 has a connector (not shown) so that a plurality of winding sections 434 can connected together by a suitable connection, such as a male-female connection. The plurality of winding sections 434 is connected at each end to an end piece 435 to form a complete mandrel 430. The plurality of winding sections 434 can be rotated about the end pieces 435.

[0252] Figure 10C is a schematic longitudinal cross-sectional view showing a tubular subassembly 424 wound around the assembled mandrel 430 of Figure 10B. The tubular subassembly 424 has been formed by the method shown in Figures 9A and 9B. Cut lines 442 (shown as doted lines in Figure 10C) show the locations at which the tubular subassembly 424 will be cut to produce tubular elements 425 each having a length Lp.

[0253] Figures 11 A and 11 B are schematic longitudinal cross-sectional views showing another example of a mandrel 430’ comprising a plurality of winding sections 434’ for winding a tubular subassembly. Such a mandrel 430’ can be used to form tubular elements having different internal diameters as shown, for example, in Figures 9A and 9B. Figure 11A shows the mandrel 430’ in a disassembled state and Figure 11 B shows the mandrel 430’ in an assembled state. Each winding section 434’ is configured to form two tubular elements. Each winding section 434’ has two first diameter sections 430a and two second diameter sections 430b, the second diameter sections 430b being adjacent each other and arranged between the two first diameter sections 430a. The first diameter sections 430a have a smaller external diameter than the second diameter sections 430b, as discussed above with respect to Figure 9A. Each winding section 434’ has a connector (not shown) so that a plurality of winding sections 434 can connected together by a suitable connection, such as a male-female connection. The plurality of winding sections 434’ is connected at each end to an end piece 435’ to form a complete mandrel 430’. The plurality of winding sections 434’ can be rotated about the end pieces 435’.

[0254] Figure 11 C is a schematic longitudinal cross-sectional view showing a tubular subassembly 424’ wound around the assembled mandrel 430’ of Figure 11 B. The tubular subassembly 424’ has been formed by the method shown in Figures 9A and 9B. Cut lines 442’ (shown as doted lines in Figure 11 C) show the locations at which the tubular subassembly 424’ will be cut to produce tubular elements 425’ each having a length Lp. As can be seen in Figure 11 C, each winding section 434’ has formed two tubular elements 425’.

[0255] Figure 12 shows a perspective view of a cutting step for cutting the tubular subassemblies such as those shown in Figures 10C and 11 C respectively. Although the mandrel 430’ and tubular subassembly 424’ of Figure 11C are illustrated, it will be appreciated that the same cutting step could be used with the mandrel 430 and tubular subassembly 424 of Figure 10C. The cutting step of Figure 12 is similar to that of Figure 7A but has been adapted to account for a tubular subassembly 424’ having different internal diameters.

[0256] In the example, of Figure 12 the tubular subassembly 424’ is cut by circular knives 443 and 444 fixed on a rotating shaft 441 , which is moved toward the central mandrel 430’ to cut and separate individual tubular elements from tubular subassembly 424’. In Figure 12, the central mandrel 430’ is shown in dashed outline with the tubular subassembly 424’. Due to the different external diameters of the central mandrel 430’, and in order to cut all the layers of the wound web material forming the tubular subassembly 424’ down to the central mandrel 430’, the circular knives have different diameters: a smaller diameter for the knives 444 aligned with the larger external diameter sections of the central mandrel 430’; and a larger diameter for the knives 443 aligned with the smaller external diameter sections of the central mandrel 430’. It will be appreciated that other methods of the cutting the tubular subassembly may be used.

[0257] Figures 13A to 13D show a series of steps for ejecting tubular elements having different internal diameters from a mandrel such as the tubular elements shown in Figures 10C and 11 C respectively. The ejection of tubular elements from a central mandrel is more complex in the case of tubular elements having different internal diameters due to the variation in the external diameter of the central mandrel and that wound web material is located between two sections of the mandrel having larger external diameters. Consequently, the tubular elements cannot simply be slid along the central mandrel. To assist with the ejection of the tubular elements, the central pin can be disassembled as described below. Although Figures 13A to 13D show the mandrel 430 and tubular subassembly 424 of Figure 10C, it will be appreciated that similar steps could be used with the mandrel 430’ and tubular subassembly 424’ of Figure 11C.

[0258] Figure 13A shows the mandrel 430 and tubular subassembly 424 of Figure 10C. In this example, each winding section 434 of the mandrel 430 is configured to form one tubular element 425. The tubular subassembly has already been cut at cut lines 442 so that individual tubular elements 425 are separable from the tubular subassembly 424. To remove the tubular elements 425, the mandrel 430 is disassembled.

[0259] Figure 13B shows one of the end pieces 435 being removed from the mandrel.

[0260] Figure 13C shows a first tubular element 425 being removed from the tubular subassembly. With the first tubular element 425 removed, it is possible to remove the first winding section 434 from the mandrel 430 because the tubular portion of the first tubular element having a smaller internal diameter is no longer obstructing the removal of the winding section 434.

[0261] Figure 13D shows the first winding section 434 being removed from the mandrel 430. The steps of Figures 13C and 13D are then repeated until all tubular elements 425 have been removed from the mandrel 430. As the winding sections 434 are removed from mandrel, they are reconnected to the removed end piece 435 from Figure 12B to form a new mandrel ready for forming another tubular subassembly.

[0262] It will be appreciated that, by combining the method of Figures 5 to 7B relating to forming tubular elements having different external diameters and the method of Figures 8 to 13D relating to forming tubular elements having different internal diameters, it is possible to form a tubular element having both different internal and external diameters, for example, the tubular element C of Figure 4. In this case, the cut sheet will have two opposing discontinuous edges and the cut sheet will be wound starting from one of the discontinuous edges.

[0263] Example

[0264] The following example details how to use the methods described herein to produce a specific tubular element, that is, the tubular element 500 shown in schematic longitudinal cross-section in Figure 14A having different external diameters and a constant internal diameter. The tubular element 500 has a first tubular portion 502 having a first external diameter D1 of 5 millimetres and a length L1 of 6 millimetres. The tubular element 500 has a second tubular portion 504 having a second external diameter D2 of 7 millimetres and a length L2 of 9 millimetres. Therefore, the overall length Lp of the tubular element 500 is 15 millimetres. The tubular element 500 has a constant internal diameter d of 3 millimetres along its whole length.

[0265] Figure 14B shows a cut-sheet 510 for forming the tubular element 500 of Figure 14A. The configuration of the cut sheet 510 of Figure 14B is similar to the cut sheet 300 of Figure Figure 5 and the dimensions of the cut sheet 500 of Figure 14B have been labelled similarly. The cut sheet 510 is configured to create a tubular subassembly of twelve tubular elements each having a length Lp of 15 millimetres. The portions of the cut sheet 510 corresponding to each of the tubular elements, that is, the portions of the cut sheet 510 having width Lp, each has a first sheet portion 510a having a width L1 of 6 millimetres and a second sheet portion 300b having a width L2 of 9 millimetres. The cut sheet 510 of Figure 14B is configured to produce six symmetrical pairs of tubular elements, each symmetrical pair being arranged back-to-back. That is, in each symmetrical pair the second sheet portions 510b are arranged adjacent each other. Each symmetrical pair of tubular elements has a length La (equal to 2Lp) of 30 millimetres and the total width of the sheet Ls (equal to 6La) is 180 millimetres.

[0266] One side of the cut sheet 510 has a continuous edge 512 and an opposing side of the cut sheet 510 has a discontinuous edge 514. A cut-out 516 has been cut from each first sheet portion 510a of the cut sheet 510 to form the discontinuous edge 514. As a result of the cutouts 516, the first sheet portions 510a have a length H1 and the second sheet portions 510b have a length H1 + H2 in a direction perpendicular to the winding axis or perpendicular to the continuous edge 512. To form the tubular element 500 having different external diameters D1 and D2, the continuous edge 512 of the cut sheet 300 will be fed on to a rotating mandrel first such that the cut sheet 500 starts to be wound around the mandrel by the continuous edge 512. The discontinuous edge 514 having cut-outs 516 will be wound last and the second sheet portions 510b will provide the extra thicknesses for the larger external diameter D2.

[0267] The web material selected to make the tubular element 500 is an uncoated 70 grams per square metre standard paper. The thickness Ts of this kind of paper is about 90 micrometres. Prior to winding, one surface of the cut sheet is coated in its entirety with a fast action adhesive such as EVA, although a long-lasting glue such as PVA may be applied in the regions of the cut sheet that will define the ends of the tubular element to adhere the edges of the sheet more firmly in these regions and prevent them collapsing into the central cavity of the tubular element. The glue thickness Tg is assumed to be 5 micrometres.

[0268] Applying equations 1 and 2 above, the number of layers N 1 of the sheet of web material needed for the first external diameter D1 of the first tubular portion 502 of the tubular element 500 is 11 and the corresponding length H1 of the first sheet portions 510a is 130 millimetres. Applying equations 1 and 2 again, the number of layers N2 of the sheet of web material needed for the second external diameter D2 of the second tubular portion 504 of the tubular element 500 is 21 and the corresponding length H1+H2 of the second sheet portions 510b is 325.5 millimetres. Therefore, the length H2 is equal to the difference in these two lengths, that is, 195.5 millimetres.

[0269] To produce twelve tubular elements a second, that is, 720 tubular elements per minute, the winding speed of the central mandrel should be 21 turns per second (1260 revolutions per minute), which is the same as the number of layers for the largest external diameter D2 of the second tubular portion 504.

[0270] Figure 15A is schematic longitudinal cross-sectional view of another tubular element 600 which has been formed by winding multiple layers 602 of a single cut-sheet of web material. Although the tubular element formed by the winding process is generally mechanically strong, as mentioned above, the edges of the layers of the web material may have a tendency to separate from their adjacent layers and to collapsing into the central cavity 604 over time. The areas within circles 606 in Figure 15A tend to be particularly susceptible to collapse. Consequently, it may be beneficial to use a longer lasting glue, such as PVA, to seek to reduce the likelihood of this happening in these areas. The innermost layer of web material closest to the central cavity 604 is held by the layers above it. Therefore, a longer lasting glue could be used in the edge areas 606 for at least some of the layers above the innermost layer.

[0271] Figure 15B is a schematic plan view of a cut-sheet 610 for forming a tubular subassembly comprising four tubular elements, each tubular element having the structure of the tubular element 600 of Figure 15A. The cut-lines 642 along which the tubular subassembly is cut to separate individual tubular elements are shown by dashed lines 642. The areas 651 of the cut-sheet 610 where a long-lasting glue, such as PVA, are applied are shown in dark shading in Figure 15B. Areas 651 correspond to the edge areas of some of layers 602 of web material above the innermost layer shown in circles 606 in Figure 15A. The remaining area of the sheet 650 is provided with a fast-acting glue, such as EVA. The fast-acting glue can either be applied over the entire remaining area 650 or over parts of it, e.g. in strips.

[0272] Figure 16 is a schematic perspective view of a gluing station 700 for gluing the cutsheet 610 of Figure 15B. The cut-sheet 610 is moved or conveyed on conveyors 702 in the direction of arrow A and pass under glue manifolds 752 and 753 comprising glue nozzles. The glue manifold 753 is used to apply fast-acting glue, such as EVA, on glue areas 650 of cutsheet 610. In this example, glue areas 650 comprise longitudinal strips of glue. The glue manifold 752 is used for deposition of long-lasting glue, such as PVA, on glue areas 651 of cut-sheet 610. In this example, glue areas 650 and 651 could be about 3 millimetres wide.

[0273] Figures 17A, 17B and 17C are schematic perspective views of a winding station 800 showing a sequence of steps for winding the cut-sheet 610 of Figure 15B. Referring to Figure 17A, the cut-sheet 610 with glue applied on its upper surface is moved or conveyed on conveyor 802 towards a winding device 804 comprising a central mandrel 830 and peripheral rollers 832. At least two of the peripheral rollers 832 are rotatably mounted on movable actuators 834.

[0274] Figure 17B shows the cut-sheet 610 contacting the bottom of central mandrel 830 of the winding device 804. The central mandrel 830 is rotating clockwise about its longitudinal axis. The glue applied on the upper surface of the cut-sheet 610 helps the cut-sheet 610 to stick to the central mandrel 830 and to start to be wound by the mandrel 830. Figure 17C shows the winding device 804 of the winding station 800 of Figure 17B in more detail. As can be seen in Figure 17C, the cut-sheet 610 has engaged the bottom of the central mandrel 830 and has started to be wound by the central mandrel 830. The peripheral rollers 832 closest to the central mandrel 830 help to conform the cut-sheet 610 to the central mandrel 830 as the cut-sheet 610 is wound.

[0275] Figure 17D shows a later step in the winding process being performed by the winding station 800. In this step, the lower ends of movable actuators 834 have pivoted outwards to bring the peripheral rollers 832 mounted at their upper ends in towards the central mandrel 830 to help enclose a portion of the central mandrel in the peripheral rollers. Figure 17E shows the winding device 804 of the winding station 800 of Figure 17D in more detail. As can be seen in Figure 17E, the outermost peripheral rollers 832 have been moved by actuators 834 to enclose the lower portion of the central mandrel 830. This helps the cut-sheet 610 to conform to the shape of the central mandrel 830. The central mandrel 830 then winds the cutsheet 610 to create a multi-layered tubular subassembly. In this example, since the desired internal diameter of the tubular elements is 3 millimetres, the central mandrel 830 has an external diameter of 3 millimetres.

[0276] Figure 18A is a schematic perspective view of a gluing and winding station 900 for gluing and winding another cut-sheet 620. In this example, the glue 955 is applied by a gluing apparatus 906 to the entirety of the lower surface of the cut-sheet 620. The cut-sheet 620 is moved or conveyed toward the gluing apparatus 906 by a conveyor 902. The gluing apparatus 906 comprises a container 954 containing a liquid glue 955, such as EVA, and a series of rollers 955 to 957 for applying glue to the cut-sheet 620. The cut-sheet 620 passes above the container 954 and the liquid glue 955 is moved by a first glue roller 956 that is partially submerged in the liquid glue 955 in the container 954 and transferred to a second glue roller 957 located in close proximity to, and vertically above, the first glue roller 956. The second glue roller 957 applies glue over the entirety of the lower surface of the cut-sheet 620. The cut-sheet 620 is pressed on the second glue roller 957 by a third roller 958 to ensure the cutsheet 620 is thoroughly covered with glue 955.

[0277] Following the gluing apparatus 906, the cut-sheet 620 with glue applied on its lower surface is moved by conveyor 902 towards a winding device 904 comprising a central mandrel 930 and peripheral rollers 932. At least two of the peripheral rollers 932 are rotatably mounted on movable actuators 934. The winding device 904 of Figure 18A is similar to that of Figure 17A with the exception that the peripheral rollers 932 are arranged about an upper portion of the mandrel 930.

[0278] Figure 18B shows the winding device 904 of Figure 18A in more detail. The cut-sheet 620 is conveyed to the mandrel 930 such that it contacts the top part of the central mandrel 930, so that its glued bottom surface is in contact with the central mandrel 930. The glue applied on the lower surface of the cut-sheet 620 helps the cut-sheet 620 to stick to the central mandrel 930 and to start to be wound by the mandrel 930. Similar to the winding device 804 of Figure 17A, the outermost peripheral rollers 932 can be moved by actuators 934 to enclose a portion of the central mandrel 930, in this example, the upper portion of the mandrel 930. This helps the cut-sheet 620 to conform to the shape of the central mandrel 930. The central mandrel 930 then winds the cut-sheet 620 to create a multi-layered tubular subassembly.

[0279] Figure 19A is a schematic longitudinal cross-sectional view of another tubular element 1000 for an aerosol-generating article. The tubular element 1000 shown in schematic longitudinal cross-section in Figure 19A has different internal diameters and a constant external diameter. The tubular element 1000 has a first tubular portion 1002 having a first internal diameter d1 and a length L1. The tubular element 1000 has a second tubular portion 1004 having a second internal diameter d2 and a length L2. The second internal diameter d2 is less than the first internal diameter d1. The internal diameter of the tubular element 1000 tapers inwards over the length L1 of the first tubular portion 1002 such that the internal diameter reduces continuously until it reaches the second internal diameter d2. The internal diameter of the tubular element 1000 tapers outwards over the length L2 of the second tubular portion 1004 such that the internal diameter increases continuously until it reaches the first internal diameter d1 again. Due to its tapered internal diameter and, in particular, its smaller second internal diameter d2, the tubular element 1000 can act as a venturi or throttle for accelerating the flow of air or aerosol through the tubular element 1000. The reduced diameter produces a low pressure region when air or aerosol is flowing through the tubular element 100 which can help homogenization of the aerosol as well as improve the quality of the aerosol.

[0280] The overall length Lp of the tubular element 1000 is equal to L1 + L2. The tubular element 1000 has a constant external diameter D along its whole length. The tubular element 1000 is formed from a single wound sheet of web material. The sheet is wound over itself so that the tubular element 1000 comprises multiple wound layers 1006 of the single sheet of web material.

[0281] Figure 19B shows a cut-sheet 1010 for forming the tubular element 1000 of Figure 19A. The configuration of the cut sheet 1010 of Figure 19B is similar to the cut sheet 300 of Figure 5 and the dimensions of the cut sheet 1010 of Figure 19B have been labelled similarly. The cut sheet 1010 is configured to create a tubular subassembly of three tubular elements each having a length Lp. The portions of the cut sheet 1010 corresponding to each of the tubular elements, that is, the portions of the cut sheet 1010 having width Lp, each has a first sheet portion 1010a having a width L1 and a second sheet portion 1010b having a width L2.

[0282] One side of the cut sheet 1010 has a continuous edge 1012 and an opposing side of the cut sheet 1010 has a discontinuous edge 1014. A cut-out 1016 has been cut from each first sheet portion 1010a of the cut sheet 1010 and a cut-out 1017 has been cut from each second sheet portion 1010b of the cut sheet 1010a to form the discontinuous edge 1014. The cut-outs 1016 and 1017 are triangular, that is, the cut edge is formed at an angle to the winding axis. The triangular cut-outs 1016 and 1017 form the tapered internal diameters of the tubular element 1000 of Figure 19A. To form the tubular element 1000 having tapered internal diameters, the discontinuous edge 1014 of the cut sheet 1010 will be fed on to a rotating mandrel first such that the cut sheet 1010 starts to be wound around the mandrel by the discontinuous edge 1014. To form individual tubular elements 1000, the tubular subassembly formed by winding cut sheet 1010 can be cut along cut-lines 1018.

[0283] Figure 20A is a schematic longitudinal cross-sectional view of another tubular element 1100 for an aerosol-generating article. The tubular element 1100 shown in schematic longitudinal cross-section in Figure 20A has a constant internal diameter d and a constant external diameter D along its whole length. The tubular element 1100 has overall length Lp. The tubular element 1100 is formed from a single wound sheet of web material. The sheet is wound over itself so that the tubular element 1100 comprises multiple wound layers 1106 of the single sheet of web material.

[0284] The tubular element 1100 has a pocket or recess 1108 formed in each of its axially opposing end surfaces 1110. In this example, the pockets or recesses 1108 have a rectangular longitudinal cross-section. The pockets or recesses 1108 extend circumferentially around each end surface 1110 and are positioned radially between the inner and outer circumferential surfaces of the tubular element 1100. The pockets or recesses 1108 extend a length L3 into the tubular element 1100. The pockets or recesses 1108 can be used to hold or collect an aerosol-generating substrate or some other form of sensorial media (not shown). This can be used to impart the aerosol with aerosol-generating substrate as the aerosol flows through the tubular element 1100. The pockets or recesses 1108 can also be used to reduce the weight of the tubular element 1100 by reducing the amount of material used to form the tubular element 1100.

[0285] Figure 20B shows a cut sheet 1120 for forming the tubular element 1100 of Figure 20A. The cut sheet 1120 is configured to create a tubular subassembly of seven tubular elements each having a length Lp. The cut sheet 1120 has a plurality of sheet portions 1121 arranged consecutively along the width of the cut sheet 1120. Each sheet portion corresponds to a tubular element 1100 and has a width Lp. The cut sheet 1120 has opposing continuous end edges extending parallel to a winding axis. The cut sheet 1120 has lateral discontinuous edges 1124. The lateral edges being perpendicular to the winding axis. A first cut-out 1126a has been cut from the left lateral edge and a second cut-out 1126b has been cut from the right lateral edge to form the discontinuous lateral edges 1124. The first and second cut-outs 1126 are rectangular and have a width L3. They are arranged as mirror images of each other. The first and second cutouts 1126 are cut at a point along the length of the cut sheet between 1120 the opposing continuous end edges 1122.

[0286] A series of further cutouts 1128 are also cut from the cut sheet 1120 and are arranged in a row across the width of the sheet of web material at a point along the length of the cut sheet 1120. The cutouts 1128 are rectangular and straddle, that is, are cut on either side of, a line of interface 1130 between adjacent sheet portions. The lines of interface 1130 also act as cut lines for cutting the tubular subassembly formed by winding cut sheet 1120. The further cutouts 1128 have twice the width of the first and second cut-outs 1126, that is, a width of 2L3. Each of the further cutouts is symmetrical, having a line of symmetry arranged along the line of interface 1130 between adjacent sheet portions 1121.

[0287] To form the tubular element 1100, one of the continuous edges 1122 of the cut sheet 1120 will be fed on to a rotating mandrel first such that the cut sheet 1120 starts to be wound around the mandrel by a continuous edge 1122. To form individual tubular elements 1100, the tubular subassembly formed by winding cut sheet 1120 can be cut along the lines of interface or cut-lines 1130.

[0288] Figure 21 A is a schematic longitudinal cross-sectional view of another tubular element 1200 for an aerosol-generating article. The tubular element 1200 shown in schematic longitudinal cross-section in Figure 21 A has a constant internal diameter d and a constant external diameter D along its whole length. The tubular element 1200 has overall length Lp. The tubular element 1200 is formed from a single wound sheet of web material. The sheet is wound over itself so that the tubular element 1200 comprises multiple wound layers 1206 of the single sheet of web material.

[0289] The tubular element 1200 has a pocket or recess 1208 formed in each of its axially opposing end surfaces 1210. In this example, the pockets or recesses 1208 have a rectangular longitudinal cross-section. The pockets or recesses 1208 extend circumferentially around each end surface 1210 and are positioned radially between the inner and outer circumferential surfaces of the tubular element 1200. The pockets or recesses 1208 extend a length L3 into the tubular element 1200. The pockets or recesses 1208 can be used to hold or collect an aerosol-generating substrate or some other form of sensorial media (not shown). This can be used to impart the aerosol with aerosol-generating substrate as the aerosol flows through the tubular element 1200. The pockets or recesses 1208 can also be used to reduce the weight of the tubular element 1200 by reducing the amount of material used to form the tubular element 1200.

[0290] Figure 21 B shows a cut-sheet 1220 for forming the tubular element 1200 of Figure 21A. The cut sheet 1220 is configured to create a tubular subassembly of seven tubular elements each having a length Lp. The cut sheet 1220 has a plurality of sheet portions 1221 arranged consecutively along the width of the cut sheet 1220. Each sheet portion corresponds to a tubular element 1200 and has a width Lp. The cut sheet 1220 has opposing continuous end edges extending parallel to a winding axis. The cut sheet 1220 has lateral discontinuous edges 1224. The lateral edges being perpendicular to the winding axis. A first cut-out 1226a has been cut from the left lateral edge and a second cut-out 1226b has been cut from the right lateral edge to form the discontinuous lateral edges 1224. In this example, the first and second cut-outs 1126 are triangular and have a width L3 at their widest points. They are arranged as mirror images of each other. The first and second cutouts 1226 are cut at a point along the length of the cut sheet between 1220 the opposing continuous end edges 1222.

[0291] A series of further cutouts 1228 are also cut from the cut sheet 1220 and are arranged in a row across the width of the sheet of web material at a point along the length of the cut sheet 1220. The cutouts 1228 are triangular and straddle, that is, are cut on either side of, a line of interface 1230 between adjacent sheet portions. The lines of interface 1230 also act as cut lines for cutting the tubular subassembly formed by winding cut sheet 1220. The further cutouts 1228 have twice the width of the first and second cut-outs 1126, that is, a width of 2L3 at their widest point. Each of the further cutouts is symmetrical, having a line of symmetry arranged along the line of interface 1230 between adjacent sheet portions 1221.

[0292] To form the tubular element 1200, one of the continuous edges 1222 of the cut sheet 1220 will be fed on to a rotating mandrel first such that the cut sheet 1220 starts to be wound around the mandrel by a continuous edge 1222. To form individual tubular elements 1200, the tubular subassembly formed by winding cut sheet 1220 can be cut along the lines of interface or cut-lines 1230.

[0293] In the above described methods where the method relates to forming a tubular subassembly comprising sheet portions for multiple tubular elements, it will be appreciated that the method can also be applied to a cut sheet for forming a single tubular element. In which case, there would be no need to cut the tubular subassembly after winding to form individual tubular elements.

[0294] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5 percent (5%) of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. A method for manufacturing a tubular element for an aerosol generating article, wherein the tubular element has a first tubular portion and a second tubular portion, wherein the method comprises: providing a sheet of sheet material having a first sheet portion corresponding to the first tubular portion and a second sheet portion corresponding to the second tubular portion; cutting a notch from an edge of a sheet of sheet material to form a discontinuous edge, wherein the notch is cut from a first portion of the sheet or a second portion of the sheet in such a way that the dimensions of the first and second portions of the sheet differ in a direction substantially perpendicular to the winding axis, wherein the discontinuous edge is substantially parallel to the winding axis; and winding a sheet of sheet material around a winding axis to form a tubular element in such a way that the tubular element comprises a plurality of wound layers of a sheet of sheet material, wherein the number of wound layers in the first tubular portion differs from the number of layers in the second tubular portion.

2. The method according to claim 1, wherein the sheet of sheet material is cut to form a polygon having at least one angle that forms an interior angle of 270 degrees.

3. The method according to claim 1 or 2, wherein the sheet comprises a plurality of first and second parts, wherein the winding of the sheet forms a tubular sub-assembly comprising a plurality of connected tubular elements.

4. The method of claim 3, wherein the sheet comprises first sheet portions of double length and second sheet portions of double length, so that the tubular subassembly comprises symmetrical pairs of tubular elements.

5. The method of claim 3 or 4, further comprising cutting the tubular subassembly to separate the individual tubular elements.

6. A method according to any of the preceding claims, wherein the sheet has a continuous edge opposite the discontinuous edge.

7. The method according to claim 6, wherein the sheet is wound starting from the discontinuous edge to form a tubular element having a first tubular portion with a first internal diameter and a second tubular portion with a second internal diameter, wherein the first internal diameter is different from the second internal diameter.

8. The method of claim 7, wherein the sheet is wound around a central mandrel having a longitudinal axis that extends along the winding axis, wherein the central mandrel has a plurality of winding sections located along its longitudinal axis, wherein the winding sections have outer diameters corresponding to the first and second inner diameters of the first and second tubular portions, respectively.

9. The method according to claim 8, wherein the winding sections can be assembled with the mandrel and detached from it.

10. The method of claim 6, wherein the sheet is wound starting from a continuous edge to form a tubular element having a first tubular portion with a first outer diameter and a second tubular portion with a second outer diameter, wherein the first outer diameter is different from the second outer diameter.

11. The method of claim 7, wherein the sheet is wound around a central mandrel having a longitudinal axis that extends along the winding axis, wherein the central mandrel has a substantially constant diameter along its longitudinal axis.

12. The method according to any one of the preceding claims, wherein the discontinuous edge comprises a first discontinuous edge and the tubular element comprises a third tubular portion, wherein the method comprises: ensuring the presence of a sheet of sheet material having a third part of the sheet corresponding to the third tubular part; cutting a notch from the edge of a sheet of sheet material opposite the first continuous edge, with the formation of a second discontinuous edge, wherein the notch is cut from a third of the sheet; winding the sheet, starting from the first discontinuous edge, to form a tubular element having different first and second internal diameters, respectively, wherein the third tubular portion has an external diameter different from the external diameter of the first and second tubular portions; or winding the sheet, starting from the second discontinuous edge, to form a tubular element having different first and second external diameters, respectively, wherein the third tubular part has an internal diameter different from the internal diameter of the first and second tubular parts.

13. The method according to any of the preceding paragraphs, further comprising applying an adhesive to the sheet of sheet material prior to winding.

14. The method of claim 13, further comprising applying heat to dry the adhesive after winding.

15. The method according to any of the preceding claims, further comprising pressing the outer surface of the sheet during winding using peripheral rollers or wheels.

16. A method for manufacturing a tubular element for an aerosol generating article, the method comprising: ensuring the presence of a sheet of sheet material, wherein the sheet of sheet material has continuous end edges running parallel to the winding axis; cutting a notch from the side edge of a sheet of sheet material, wherein the side edge is perpendicular to the winding axis, and the notch is cut at a point along the length of the sheet between the end edges to form a discontinuous side edge; winding a sheet of sheet material around a winding axis to form a tubular element; wherein the sheet of sheet material comprises a plurality of sheet portions arranged sequentially along the width of the sheet of sheet material, wherein each sheet portion corresponds to a tubular element, wherein the winding of the sheet forms a tubular sub-assembly comprising a plurality of connected tubular elements; wherein the method further comprises cutting a sequence of cuts from a sheet of sheet material, wherein the sequence of cuts is arranged in a row across the width of the sheet of sheet material at a point along the length of the sheet, wherein the cuts are cut on both sides of the mating line between adjacent parts of the sheet.

17. The method according to claim 16, wherein the cutout has a triangular shape.

18. The method according to claim 16, wherein the cutout has a rectangular shape.

19. The method according to any one of paragraphs 16-18, wherein the cutout is a first cutout and is cut from a first side edge, and the method further comprises cutting a second cutout from a second opposite side edge of the sheet of sheet material.

20. The method according to claim 19, wherein the first and second cutouts are mirror images of each other.

21. The method according to claim 16, wherein each cutout from the sequence of cutouts is symmetrical, and the line of symmetry is located along the mating line between adjacent parts of the sheet.

22. The method of any one of paragraphs 16-21, further comprising cutting the tubular subassembly along each mating line to separate the individual tubular elements.