INDUCTIVELY HEATABLE AEROSOL-GENERATING ARTICLE, METHOD FOR MANUFACTURING SUCH AN ARTICLE AND AN APPARATUS FOR MANUFACTURING A SUSCEPTOR OF SUCH AN ARTICLE

Abstract

An inductively heatable aerosol-generating article for an inductively heating aerosol-generating device is provided, including at least one aerosol-forming substrate and at least one susceptor in thermal proximity to the aerosol-forming substrate or thermal contact with the aerosol-forming substrate, the susceptor including an expanded metal sheet including a plurality of openings through the sheet. A method for manufacturing an inductively heatable aerosol-generating article is also provided. An apparatus for manufacturing a susceptor of an inductively heatable aerosol-generating article is also provided.

Claims

1.-13. (canceled)

14. An inductively heatable aerosol-generating article for an inductively heating aerosol-generating device, the article comprising: at least one aerosol-forming substrate; and at least one susceptor in thermal proximity with the at least one aerosol-forming substrate or thermal contact with the at least one aerosol-forming substrate, the at least one susceptor comprising a flattened expanded metal sheet comprising a plurality of openings through the flattened expanded metal sheet.

15. The inductively heatable aerosol-generating article according to claim 14, wherein the plurality of openings is arranged in a periodic pattern.

16. The inductively heatable aerosol-generating article according to claim 14, wherein one or more of the plurality of openings have a rhombus shape.

17. The inductively heatable aerosol-generating article according to claim 16, wherein the rhombus shape has a first diagonal connecting a first pair of opposite vertices of the rhombus shape and a second diagonal connecting a second pair of opposite vertices of the rhombus shape, and wherein the first diagonal extends in a direction of expansion of the expanded metal sheet.

18. The inductively heatable aerosol-generating article according to claim 17, wherein a length of the first diagonal is in a range of 1.7 millimeter to 4.7 millimeter, and a length of the second diagonal is in a range of 0.3 millimeter to 3.1 millimeter.

19. The inductively heatable aerosol-generating article according to claim 14, wherein one or more of the plurality of openings are laterally opened up towards a side edge of the flattened expanded metal sheet and have a triangular shape.

20. The inductively heatable aerosol-generating article according to claim 14, wherein the at least one aerosol-forming substrate is arranged at least partially around the at least one susceptor.

21. The inductively heatable aerosol-generating article according to claim 14, wherein the at least one aerosol-forming substrate comprises a non-tobacco plant material.

22. The inductively heatable aerosol-generating article according to claim 14, wherein the at least one aerosol-forming substrate comprises an aerosol-former with a weight proportion in a range of 12 percent to 20 percent by weight of the at least one aerosol-forming substrate.

23. A method for manufacturing an inductively heatable aerosol-generating article according to claim 14, the method comprising the steps of: providing an aerosol-forming substrate; providing a susceptor comprising a flattened expanded metal sheet comprising a plurality of openings, wherein the providing the susceptor comprises the steps of: providing a metal sheet, creating a plurality of weakened areas in the metal sheet, stretching the weakened metal sheet at least along a first direction so as to create an expanded metal sheet comprising a plurality of openings originating from the plurality of weakened areas, and flattening the expanded metal sheet after the stretching; and arranging the susceptor in thermal proximity to the aerosol-forming substrate or thermal contact with the aerosol-forming substrate.

24. The method according to claim 23, wherein the creating the plurality of weakened areas comprises creating a plurality of slits of finite length into the metal sheet, and wherein at least a portion of each slit extends along a second direction transverse to the first direction.

25. The method according to claim 24, wherein one or more of the plurality of weakened areas comprise one of: a straight slit, a curved slit, a C-shaped slit, a U-shaped slit, a sickle-shaped slit, a cross-shaped slit, or a T-shaped slit.

26. An apparatus for manufacturing a susceptor of an aerosol-generating article according to claim 14, the apparatus comprising: a first pair of counter-rotating first rolls, wherein at least one of the first rolls comprises one or more cutting elements arranged on an outer circumferential surface of the respective roll, and wherein the one or more cutting elements are configured to create a plurality of weakened areas, in particular a plurality of slits in the metal sheet when the metal sheet passes between the first rolls of the first pair; a second pair of counter-rotating second rolls, arranged downstream of the first pair of first rolls, configured to convey the weakened metal sheet therebetween at a first conveying velocity corresponding to a rotational speed of the second rolls; a third pair of counter-rotating third rolls, arranged downstream of the second pair of second rolls, configured to convey the weakened metal sheet therebetween at a second conveying velocity corresponding to a rotational speed of the third rolls, wherein a rotational speed of the third rolls is higher than the rotational speed of the second rolls such that the weakened metal sheet, when being conveyed by the second and the third pair of rolls, is stretched along a direction of conveyance thereby turning into an expanded metal sheet comprising a plurality of openings through the expanded metal sheet originating from the plurality of weakened areas; and a fourth pair of counter-rotating fourth rolls, arranged downstream of the third pair of third rolls, configured to convey the expanded metal sheet therebetween at a third conveying velocity corresponding to a rotational speed of the fourth rolls, wherein the rotational speed of the fourth rolls is higher than the rotational speed of the third rolls such that the expanded metal sheet, when being conveyed by the third and the fourth pair of rolls, is straightened and flattened.

Description

[0170] The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0171] FIG. 1 is a schematic illustration of an inductively heatable aerosol-generating article according to an exemplary embodiment of the present invention;

[0172] FIG. 2 is a schematic illustration an exemplary embodiment of an aerosol-generating system comprising an aerosol-generating device and the aerosol-generating article according to FIG. 1;

[0173] FIG. 3 illustrates a further exemplary embodiment of a susceptor which may be used to form an aerosol-generating article according to FIG. 1; and

[0174] FIG. 4 schematically illustrate an exemplary embodiment of an apparatus for manufacturing a susceptor which may be used to form an aerosol-generating article according to the present invention.

[0175] FIG. 1 schematically illustrates an exemplary embodiment of an inductively heatable aerosol-generating article 1 according to the present invention. The aerosol-generating article 1 substantially has a rod-shape and comprises four elements sequentially arranged in coaxial alignment: an aerosol-forming rod 10 comprising a susceptor 20 and an aerosol-forming substrate 30, a support element 40, an aerosol-cooling element 50, and a filter element 60. The aerosol-forming rod 10 is arranged at a distal end 2 of the article 1, whereas the filter element 60 is arranged at a proximal end 3 of the article 1. The support element 40 may comprise a cartoon- or cellulose-based tube having a central air passage 41 which allows for mixing and homogenization of any aerosols generated inside the aerosol-forming rod 10. Alternatively, the support element 40 may be used for keeping separate different aerosols generated at different places inside the aerosol-forming rod separate until reaching the aerosol-cooling element 50. The aerosol-cooling element 50 mainly serves to reduce the aerosol temperature towards the proximal end 3 of the article 1. The aerosol-forming element may, for example, comprise biodegradable polymeric materials, cellulose-based materials with low porosity or combinations of these and other materials. The filter element 60 serves as a mouthpiece, possibly together with at least a portion of the aerosol-cooling element 50, through which the aerosol exits the aerosol-generating article 1. The filter element 60 may comprise standard filter materials, for example low density acetate tow. Each of the four elements 10, 40, 50, 60 is substantially cylindrical, all of them having substantially the same diameter or circumference. In addition, the four elements are circumscribed by an outer wrapper 70 such as to keep the four elements together and to maintain the desired circular cross-sectional shape of the rod-like article 1. The wrapper 70 preferably is made of paper.

[0176] The rod-shaped aerosol-generating article 1 may have a length between 30 millimeter and 110 millimeter, preferably between 40 millimeter and 60 millimeter. Likewise, the article 1 may have a diameter between 3 millimeter and 10 millimeter, preferably between 5.5 millimeter and 8 millimeter. Further details of the article, in particular of the four elements—apart from the specifics of the susceptor 20 within the rod 10—are disclosed in WO 2015/176898 A1.

[0177] As illustrated in FIG. 2, the aerosol-generating article 1 is configured for use with an inductively heating aerosol-generating device 80. Together, the device 80 and the article 1 form an aerosol-generating system 90. The aerosol-generating device 80 comprises a cylindrical receiving cavity 82 defined within a distal portion of the device housing 81 for receiving a least a distal portion of the article 1 therein. The device 80 further comprises an induction source including an induction coil 83 for generating an alternating, in particular high-frequency electromagnetic field. In the present embodiment, the induction coil 83 is a helical coil circumferentially surrounding the cylindrical receiving cavity 82 such that the susceptor 20 of the article 1 may experience the electromagnetic field of the coil when the article 1 is received in the cavity 82. Thus, upon activating the induction source, the susceptor element 20 heats up until reaching a temperature sufficient to release material from the aerosol-forming substrate 30 surrounding the susceptor 20.

[0178] As can be further seen in FIG. 2, the device 80 further comprises a power supply 85 and a controller 84 (only schematically illustrated in FIG. 2) for powering and controlling the heating process. Preferably, the induction source is at least partially integral part of the controller 84.

[0179] According to the invention, the susceptor 20 is in thermal contact with the aerosol-forming substrate 30. In the embodiment of the article 1 as shown in FIG. 1 and FIG. 2, the aerosol-forming substrate 30 surrounds the susceptor 20 such as to define the overall cylindrical shape of the rod 10. The elongate susceptor 20 is substantially strip-shaped and arranged along a central axis of the article 1.

[0180] As seen in a plane perpendicular to the central axis of the article 1, the strip-shaped susceptor 20 has a rectangular cross-sectional profile, wherein a thickness extension of the susceptor 20 is smaller than a width extension 27 which in turn is smaller than a length extension 28 along the central axis. As can be seen in FIG. 1 and FIG. 2 The length 28 is approximately the same as the length of the aerosol-forming substrate 30, that is, the length of the rod 10.

[0181] According to the invention, the susceptor comprises an expanded metal sheet 21 which comprises a plurality of openings 22, 23 extending through the sheet 21 along its thickness extension. As will be described in more detail below, the openings 22, 23 in the expanded metal sheet 21 result from locally weakening, in particular perforating, and subsequently stretching a metal sheet such to form a regular pattern of openings originating from the expansion of the locally weakened areas of the metal sheet, in particular from the perforations in the metal sheet.

[0182] As described above, using an expanded metal sheet as susceptor 20 advantageously allows to save materials and production costs, and thus to conserve resources. In addition, due to the plurality of openings 22, 23, the susceptor 20 is permeable causing the airflow drawn through the article 1 to be enhanced as compared to an article comprising a non-permeable susceptor. In addition, the openings 22, 23 facilitate the release and entrainment of material that is volatilized from the heated aerosol-forming substrate 30 into the airflow through the article 1.

[0183] In the present embodiment, the expanded metal sheet 21 of the susceptor 20 comprises two types of openings, namely, openings 22 having a closed boundary, that is, which are completely bounded by the material of the expanded metal sheet 21, and openings 23 having a partially open boundary, that is, which are only partially bounded by the material of the expanded metal sheet 21. The latter are located at both side edges of the strip-shaped susceptor 20. That is, the openings 23 are laterally opened up towards a respective side edge.

[0184] As shown in FIG. 1 and FIG. 2, the openings 22 have a substantially rhombus shape, whereas the openings 23 have a substantially triangular shape. In the present embodiment, both types of openings 22, 23 result from the expansion of perforations which have been created in into a metal sheet prior to expansion. The perforations are substantially straight slits of finite length that have been cut into the metal sheet prior to expansion. The slits which result in the partially unbound openings 23 upon expansion have been cut such as to extend beyond the side edge of the metal sheet. In contrast, the slits which result in the bounded openings 22 have been cut such as to be completely within the boundaries of the metal sheet. In the present embodiment, the both types of slits are oriented perpendicular to the direction along the metal sheet has been expanded, which is the length extension of the expanded metal sheet 21.

[0185] As can be further seen in FIGS. 1 and 2, the expanded metal sheet 21 comprises a single row of rhombus-shaped openings 22 along a center line of the strip-shaped susceptor 20, that is, parallel to its length extension. Between each neighboring rhombus-shaped openings 22, two partially bounded openings 23 are arranged in an offset configuration at opposite side edges of the strip-shaped susceptor 20. Due to this periodic offset pattern of the openings 22, 23, the susceptor 20 advantageously has an increased density of openings per unit area which results in high permeability and a low total mass per unit area. The rhombus-shaped openings 22 have a first diagonal connecting a first pair of opposite vertices of the rhombus shape and a second diagonal connecting a second pair of opposite vertices of the rhombus shape. As described above, the first diagonal extends in a first direction which corresponds to the direction of expansion of the expanded metal sheet, which in turn is perpendicular to the length extension of the straight slits from which the rhombus-shaped openings 22 result upon expansion. The length of the first diagonal may be in a range of 0.3 millimeter to 3.1 millimeter, preferably in a range of 0.5 millimeter 2.5 millimeter. Likewise, the length of the second diagonal is in a range of 1.7 millimeter to 4.7 millimeter, preferably in a range of 1.1 millimeter to 3.1 millimeter. The shortest distance between the rhombus-shaped openings and the closest side edge of the strip-shaped metal sheet 21 of the susceptor 20 may be in a range of 1.7 millimeter to 4.3 millimeter, preferably in a range of 1.5 millimeter 2.0 millimeter. The length of the open edge of the triangular openings 23 along the side edge of the susceptor 20 may be in a range of 0.2 millimeter to 2.7 millimeter, preferably in a range of 0.3 millimeter 1.1 millimeter.

[0186] Depending on the width of the strip-shaped susceptor and the size of the openings, the susceptor may comprise more than one row of completely bounded openings. Such a configuration is illustrated in FIG. 3 which shows an alternative embodiment of a strip-shaped susceptor 120. The strip-shaped susceptor 120 according to this embodiment comprises two rows of rhombus-shaped openings 122 symmetrically arranged along a center line of the susceptor 120 parallel to its length extension. Between each neighboring rhombus-shaped openings 122, the susceptor 120 comprises one central rhombus-shaped opening 124 and two partially bounded openings 123 at the opposite side edges of the susceptor 120. The central rhombus-shaped opening 124 and the two partially bounded openings 123 are arranged in an offset configuration relative to the rhombus-shaped openings 122 in the respective neighboring rows.

[0187] With regard to both embodiments of the susceptor 20, 120, the respective expanded metal sheet 21, 121 preferably is a bi-layer sheet comprising a first layer made of ferromagnetic stainless steel which comprises at least on one side a nickel coating which forms a second of the bi-layer sheet. Due to the magnetic and electrical properties of ferromagnetic stainless steel, the first layer is inductively heated due to both, eddy currents and hysteresis loss. Hence, the first layer is optimized with regard to heat loss and thus provides the main heating. In contrast, the second layer primarily is used as temperature marker. This is based on the magnetic properties of nickel having a Curie temperature which is approximately the same as the temperature that the susceptor 20 should be heated to in order to generate an aerosol from the substrate 30, but which is still low enough to avoid local overheating or burning of the substrate 30.

[0188] FIG. 4 schematically illustrate an exemplary embodiment of an apparatus 200 for manufacturing a susceptor 120 which may be used to form an aerosol-generating article according to the present invention.

[0189] Preferably, the apparatus 200 may be used to perform at least parts of the method according to the present invention for manufacturing an inductively heatable aerosol-generating article, in particular to perform the step of providing a susceptor which comprises an expanded metal sheet comprising a plurality of openings.

[0190] The upper part of FIG. 4 illustrates the apparatus 200 itself, whereas the lower part of FIG. 4 illustrates the functioning and results of the different units of the apparatus 200 and of the different sub-steps of providing a susceptor 120.

[0191] According to the invention, the step of providing a susceptor 120 starts with providing a metal sheet 190. Preferably, the metal sheet 190 is provided as a continuous metal sheet, for example as a metal tape, provided on a bobbin. For this, the apparatus may comprise an unwinding unit to unwind the continuous metal sheet from the bobbin (not shown).

[0192] Next, the step of providing a susceptor 120 comprises the step of creating a plurality of weakened areas in the metal sheet. In the embodiments, the weakened areas are perforations in the metal sheet. For this, the apparatus 200 comprises a slitter 201. The slitter 201 comprises a first pair 210 of counter-rotating first roles 211, 212 which the metal sheet 190 is fed in between at an upstream end of the apparatus 200. At least one of the first rolls 211, 212 comprises one or more cutting elements arranged on the outer circumferential surface of the respective roll 211, 212 (not shown). The one or more cutting elements are configured to create a plurality of perforations in the metal sheet 190 when the metal sheet 190 passes between the first rolls 211, 212. Accordingly, this process results in a perforated metal sheet 180 at the downstream end of the slitter 201. In the present embodiment of the apparatus 200, the cutting elements of the slitter 201 are configured to create a periodic pattern of straight slits 182, 183 which extend perpendicular to the direction of travel of the metal sheet through the apparatus 200. As shown in the lower part of FIG. 4 (second sub-figure from the right), the resulting perforated metal sheet 180 comprises slits 182 which are completely within the boundaries of the metal sheet, as well as slits 183 which extend beyond the side edge of the metal sheet.

[0193] Next, the step of providing a susceptor 120 comprises the step of stretching the weakened, in particular perforated metal sheet 180 at least along a first direction such as to create an expanded metal sheet 190 comprising a plurality of openings originating from the plurality of perforations 182, 183. For this, the apparatus 200 comprises an expansion unit 202.

[0194] The expansion unit 202 includes a second pair 220 of counter-rotating second rolls 221, 222, arranged downstream of the first pair 210 of first rolls 211, 212. The second rolls 221, 222 are configured to convey the weakened, in particular perforated metal sheet 180 therebetween at a first conveying velocity V1 corresponding to a rotational speed of the second rolls 221, 222. Preferably, a rotational speed of the first rolls 211, 212 is equal to the rotational speed of the second rolls 221, 222 such that no stretching occurs between the first pair 210 of first rolls 211, 212 and the second pair 220 of second rolls 221, 222.

[0195] Downstream of the second pair 220 of second rolls 221, 222, the expansion unit 202 comprises a third pair 230 of counter-rotating third rolls 231, 232 which are configured to convey the weakened, in particular perforated metal sheet 180 therebetween at a second conveying velocity V2 corresponding to a rotational speed of the third rolls 231, 232. The rotational speed of the third rolls 231, 232 is higher than the rotational speed of the second rolls 221, 222 such that the weakened, in particular perforated metal sheet 180—when being conveyed by the second and third pair of rolls 220, 230—is stretched along the direction of conveyance. Thereby, the weakened, in particular perforated metal sheet 180 is turned in an expanded metal sheet 170 which comprises a plurality of openings 172, 173 originating from the plurality of perforations 182, 183.

[0196] Downstream of the third pair 230 of third rolls 231, 232, the apparatus 200 comprise a flattening unit 203. The flattening unit 203 comprises a fourth pair 240 of counter-rotating fourth rolls 241, 242 which are configured to convey the expanded metal sheet 170 therebetween at a third conveying velocity V3 corresponding to a rotational speed of the fourth rolls 241, 242. The rotational speed of the fourth rolls 241, 242 is chosen to be higher than the rotational speed of the third rolls 231, 232 such that the expanded metal sheet 170—when being conveyed by the third and fourth pair of rolls 230, 240—is straightened and flattened.

[0197] At the downstream end of the apparatus 200, the above described steps finally result in a (continuous) flattened expanded metal sheet 200 which may be used to form a susceptor 120 as shown in FIG. 3.

[0198] As further illustrated in FIG. 4, the apparatus 200 may further comprise an adjustment mechanism 215, 225, 235, 245 for each of the first, second, third and fourth pair of rolls 210, 220, 230, 240. The respective adjustment mechanism 215, 225, 235, 245 is configured to adjust the distance between the rolls of a respective pair 210, 220, 230, 240 as well as an orientation, in particular an inclination of a rotational axis of each roll a respective pair of rolls 210, 220, 230, 240.

[0199] As described above, the apparatus 200 preferably is used to perform the step of providing a susceptor according to the method of the present invention, in particular in case the method is realized as a continuous process. According to this aspect, the method may further comprise—in parallel, prior or after providing the susceptor—the step of providing a substrate web comprising an aerosol-forming substrate. Subsequently, the method may comprise step of gathering the substrate web around the susceptor profile such as to form a continuous rod-shaped strand having a cylindrical shape with a constant cross-section and next the step of cutting the continuous rod-shaped strand into individual aerosol-forming rods. The aerosol-forming rods resulting from this method may be directly used as aerosol-generating article. Alternatively, the aerosol-forming rods 10 may be used to form an aerosol-generating article 1 as shown in FIG. 1.