INDUCTIVELY HEATABLE AEROSOL-FORMING RODS AND SHAPING DEVICE FOR USAGE IN THE MANUFACTURING OF SUCH RODS

Abstract

An inductively heatable aerosol-forming rod for an aerosol-generating article is provided, including a first cylindrical core portion including at least one of a first aerosol-forming substrate and a first flavoring material; a second cylindrical core portion separate from the first core portion including at least one of a second aerosol-forming substrate and a second flavoring material; at least one elongate susceptor laterally abutting the first and the second core portions in a non-bond manner such that the susceptor is sandwiched between the first and the second core portions; a sleeve portion arranged around the first and the second core portions and the susceptor, and including at least one of a filler material, a third aerosol-forming substrate, and a third flavoring material. A shaping device for manufacturing of the rods is also provided, including a core-forming device, a first sleeve-forming device, a second sleeve-forming device, and a longitudinal guide.

Claims

1.-15. (canceled)

16. An inductively heatable aerosol-forming rod for an aerosol-generating article, the aerosol-forming rod comprising: a first cylindrical core portion comprising at least one of a first aerosol-forming substrate and a first flavoring material; a second cylindrical core portion separate from the first core portion and comprising at least one of a second aerosol-forming substrate and a second flavoring material; at least one elongate susceptor laterally abutting the first core portion and the second core portion in a non-bond manner such that the susceptor is sandwiched between the first core portion and the second core portion; a sleeve portion arranged around the first core portion, the second core portion, and the susceptor, the sleeve portion comprising at least one of a filler material, a third aerosol-forming substrate, and a third flavoring material; and a wrapper entirely surrounding the sleeve portion.

17. The inductively heatable aerosol-forming rod according to claim 16, wherein at least one of the first core portion and the second core portion comprises at least one of: a porous substrate or foam based on tobacco fibers, wherein the tobacco fibers at least partially form the first aerosol-forming substrate or the second aerosol-forming substrate, respectively, a porous substrate or foam based on botanical fibers, wherein the botanical fibers at least partially form the first aerosol-forming substrate or the second aerosol-forming substrate, respectively, a filler comprising a cut tobacco material, wherein the cut tobacco material at least partially forms the first aerosol-forming substrate or the second aerosol-forming substrate, respectively, a filler comprising a cut botanical material, wherein the cut botanical material at least partially forms the first aerosol-forming substrate or the second aerosol-forming substrate, respectively, a liquid retention material including an aerosol-forming liquid, wherein the aerosol-forming liquid at least partially forms the first aerosol-forming substrate or the second aerosol-forming substrate, respectively, a liquid retention material including at least one flavoring substance, wherein the flavoring substance at least partially forms the first flavoring material or the second flavoring material, respectively, cellulose fibers or cellulose-based fibers, including a flavoring substance, wherein the flavoring substance at least partially forms the first flavoring material or the second flavoring material, respectively.

18. The inductively heatable aerosol-forming rod according to claim 16, wherein the sleeve portion comprises at least one of: a porous substrate or foam based on tobacco fibers, wherein the tobacco fibers at least partially form the third aerosol-forming substrate, a porous substrate or foam based on botanical fibers, wherein the botanical fibers at least partially form the third aerosol-forming substrate, a filler comprising a cut tobacco material, wherein the cut tobacco material at least partially forms the third aerosol-forming substrate, a filler comprising a cut botanical material, wherein the cut botanical material at least partially forms the third aerosol-forming substrate, a liquid retention material including an aerosol-forming liquid, wherein the aerosol-forming liquid at least partially forms the third aerosol-forming substrate, a liquid retention material including at least one flavoring substance, wherein the flavoring substance at least partially forms the third flavoring material, cellulose fibers or cellulose-based fibers, cellulose fibers or cellulose-based fibers, including a flavoring substance, wherein the flavoring substance at least partially forms the third flavoring material, acetate tow expanded fibers, botanical expanded fibers, or paper.

19. The inductively heatable aerosol-forming rod according to claim 16, wherein the second aerosol-forming substrate is different from the first aerosol-forming substrate.

20. The inductively heatable aerosol-forming rod according to claim 16, wherein the third aerosol-forming substrate is different from at least one of the first aerosol-forming substrate and the second aerosol-forming substrate.

21. The inductively heatable aerosol-forming rod according to claim 16, wherein at least one of the first core portion and the second core portion has a rectangular cross-section, or quadratic cross-section, or a semi-elliptical cross-section, or semi-circular cross-section.

22. The inductively heatable aerosol-forming rod according to claim 16, wherein the susceptor is symmetrically arranged with respect to a longitudinal center axis of the aerosol-forming rod.

23. The inductively heatable aerosol-forming rod according to claim 16, wherein the susceptor comprises an expanded metal sheet comprising a plurality of openings through the sheet.

24. An aerosol-generating article comprising an inductively heatable aerosol-forming rod according to claim 16.

25. A shaping device for manufacturing of inductively heatable aerosol-forming rods according to claim 16, the shaping device comprising: a first core-forming device configured to gather a first core material, comprising at least one of the first aerosol-forming substrate and the first flavoring material, into a first continuous core strand such that upon passing through the first core-forming device the first continuous core strand has a cross-sectional shape corresponding to a cross-sectional shape of the first cylindrical core portion; a second core-forming device configured to gather a second core material, comprising at least one of the second aerosol-forming substrate and the second flavoring material, into a second continuous core strand such that upon passing through the second core-forming device the second continuous core strand has a cross-sectional shape corresponding to a cross-sectional shape of the second cylindrical core portion, wherein the first core-forming device and the second core-forming device are separate from each other, wherein a shape of an inner cross-section of the first core-forming device, in particular a shape of an inner cross-section of a downstream section of the first core-forming device, corresponds to the cross-sectional shape of the first cylindrical core portion and wherein a shape of an inner cross-section of the second core-forming device, in particular a shape of an inner cross-section of a downstream section of the second core-forming device, corresponds to the cross-sectional shape of the second core portion, or wherein the first core-forming device and the second core-forming device are at least partially realized by a common core-forming device, and wherein a shape of an inner cross-section of the common core-forming device, in particular a shape of an inner cross-section of a downstream section of the common core-forming device, corresponds to the cross-sectional envelope of the first core portion and the second core portion; a longitudinal guide configured to arrange a continuous susceptor profile between the first continuous core strand and the second continuous core strand, wherein the longitudinal guide extends downstream at least into an upstream section of at least one of the first core-forming device and the second core-forming device; and a sleeve-forming device arranged around at least a downstream section of the first and the second core-forming devices and configured to gather a sleeve material, comprising at least one of the filler material, the third aerosol-forming substrate, and the third flavoring material, into a continuous sleeve strand around the first continuous core strand, the second continuous core strand, and the continuous susceptor profile such that the continuous sleeve strand has a cross-sectional shape corresponding to a cross-sectional shape of the sleeve portion.

26. The shaping device according to claim 25, wherein the sleeve-forming device further comprises an outer funnel arranged around at least a downstream section of the first core-forming device and the second core-forming device.

27. The shaping device according to claim 25, wherein the first core-forming device and the second core-forming device are at least partially realized by a common inner funnel.

28. The shaping device according to claim 25, further comprising a first translation stage configured to adjust at least an axial position of the longitudinal guide relative to at least one of the first core-forming device and the second core-forming device, or the common core-forming device, respectively.

29. The shaping device according to claim 25, further comprising one or more guiding fins arranged at an inner surface of the sleeve-forming device.

30. The shaping device according to claim 25, wherein the longitudinal guide comprises a guiding tube.

Description

[0147] The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0148] FIG. 1 is a schematic illustration of an inductively heatable aerosol-generating article comprising an inductively heatable aerosol-forming rod according a first embodiment of the present invention;

[0149] FIG. 2 is a cross-sectional view of the article according to FIG. 1;

[0150] FIG. 3 is a cross-sectional view of an article according to a second embodiment of the present invention;

[0151] FIG. 4 schematically illustrates the manufacturing of inductively heatable aerosol-forming rods according to the present invention;

[0152] FIG. 5 is a schematic illustration of a shaping device for usage in the manufacturing of inductively heatable aerosol-forming rods according to FIG. 2;

[0153] FIG. 6 is a schematic illustration of a shaping device for usage in the manufacturing of inductively heatable aerosol-forming rods according to FIG. 3; and

[0154] FIG. 7 details of an example of a susceptor of the aerosol-forming rods according to FIG. 2 and FIG. 3.

[0155] FIG. 1 and FIG. 2 schematically illustrate a first embodiment of an inductively heatable aerosol-generating article according to the present invention. The article 1 substantially has a rod-shape and comprises four elements which are arranged in coaxial alignment along the longitudinal axis 7 of the article 1: an aerosol-forming rod 10 according to the present invention, a support element 60, an aerosol-cooling element 70, and a filter element 80. The aerosol-forming rod 10 is arranged at a distal end 2 of the article 1, whereas the filter element 80 is arranged at a distal end 3 of the article 1. Optionally, the article 1 may further comprise a distal front-element 60 which may be used to cover and protect the distal front end of the aerosol-forming rod 10. Each of the aforementioned elements is substantially cylindrical, all of them having substantially the same diameter. In addition, the elements are circumscribed by an outer wrapper 90 such as to keep the elements together and to maintain the desired circular cross-sectional shape of the rod-shaped article 1. Preferably, the wrapper 90 is made of paper.

[0156] 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.

[0157] The support element 60 may comprise a cartoon- or cellulose-based tube 62 having a central air passage 61 which allows for mixing and homogenization of any aerosols generated inside the aerosol-forming rod 10. Alternatively, the support element 60 may be used for keeping separate different aerosols generated at different places inside the aerosol-forming rod separate until reaching the aerosol-cooling element 70.

[0158] The aerosol-cooling element 70 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.

[0159] The filter element 80 may comprise standard filter materials, for example low density acetate tow.

[0160] Either the filter element 80 alone or both, the aerosol-cooling element 70 and the filter element 80 may serve as mouthpiece through which the aerosol exits the aerosol-generating article 1.

[0161] In the embodiment shown in FIG. 1 and FIG. 2, the aerosol-forming rod segment 10 has a cylindrical shape with a constant cross-section, for example circular cross-section. As part of the article 1, the aerosol-forming rod 10 may have a length between 5 millimeter and 20 millimeter, preferably between 7 millimeter and 13 millimeter. The diameter of the aerosol-forming rod 10 may be in a range between 3 millimeter and 10 millimeter, preferably between 5.5 millimeter and 8 millimeter.

[0162] As shown in FIG. 1 and FIG. 2, the aerosol-forming rod comprises at least four components: a first cylindrical core portion 30 which includes at least one of a first aerosol-forming substrate and r a first flavoring material, a second cylindrical core portion 50 which includes at least one of a second aerosol-forming substrate and a second flavoring material, an elongate susceptor 40 which is sandwiched between the first cylindrical core portion 30 and the second cylindrical core portion 50, and a sleeve portion 20 which is arranged around the core portions 30, 50 and the susceptor 40 and which comprises at least one of a filler material, a third aerosol-forming substrate and a third flavoring material.

[0163] In the present embodiment, the first core portion 30 comprises a liquid retention material 31 which is impregnated with a liquid (first) flavoring material. In contrast, the second core portion 50 comprises a liquid retention material 51 which is impregnated with a liquid aerosol-forming substrate. The sleeve portion 20 comprises acetate tow expanded fibers 21. The susceptor 40 is an elongate strip made of ferromagnetic stainless steel. This material may be advantageous as it provides heat due to both, eddy currents and hysteresis losses. Optionally, the susceptor 40 may comprise a nickel coating, wherein nickel mainly serves as temperature marker as described further above. In addition, the susceptor 40 may comprises a protective coating to prevent undesired aging of the susceptor 40, for example, due to corrosion in the moist environment of the aerosol-forming substrates and flavoring materials.

[0164] As can be further seen in FIG. 1 and FIG. 2, the susceptor 40 according to the present embodiment is strip-shaped, having a width dimension in a range between 3.5 millimeter and 8 millimeter, preferably between 4 millimeter and 6 millimeter, and a thickness dimension in a range between 0.05 millimeter and 0.4 millimeter, preferably between 0.15 millimeter and 0.35 millimeter. The first core portion 30 and the second core portion 50 are strip-shaped, too. They have a width dimension in a range between 3.5 millimeter and 8 millimeter, preferably between 4 millimeter and 6 millimeter, and a thickness dimension in a range between 0.5 millimeter and 7 millimeter, preferably between 2 millimeter and 5 millimeter. In particular, the susceptor 40 may be a susceptor made of an expanded metal sheet comprising a plurality of openings 41 through the sheet. An example of such a susceptor 40 is shown in FIG. 7.

[0165] As can be further seen in FIG. 1 and FIG. 12, a large side of the susceptor 40 laterally abuts a respective large side of the first cylindrical core portion 30 and the second cylindrical core portion 50 along a longitudinal axis 7 of the rod 10. Thus, the susceptor 40 is in direct physical contact with both, the first core portion 30 and the second core portion 50. Due to this, the aerosol-forming rod 10 allows for a simultaneous production of aerosols and flavoring additives. Advantageously, this enhances the diversity of generable aerosols. In addition, the direct physical contact between the susceptor and the core portions allows for good heating efficiency.

[0166] The contact between the susceptor 40 and the first core portion 30 and between the susceptor 40 and the second core portion 50, respectively, is of a non-bonded nature, that is, the susceptor 40 and the respective core portion 30, 50 are not fixedly attached to each other. Nevertheless, the contact between the susceptor 40 and the respective portion 30, 50 may include some kind of non-permanent adhesion, for example, due to wet or moist nature of the liquid retention material that is impregnated with liquid flavoring material or liquid aerosol-forming substrate, respectively.

[0167] The sleeve portion 20 is arranged around the susceptor 40, the first core portion 30 and the second core portion 50 such that the acetate tow expanded fibers 21 of the sleeve portion 20 completely fills the entire residual volume of the cylindrical rod 10.

[0168] FIG. 3 shows a second embodiment of an aerosol-forming rod 10 according to the present invention. It is substantially identical to the aerosol-forming rod according to FIG. 1 and FIG. 2. Therefore, identical or similar features are denoted with identical reference numerals. The aerosol-forming rod 10 according to the second embodiment differs from the aerosol-forming rod 10 according to the first embodiment by the cross-sectional shape of the first core portion 30 and the second core portion 50, which is not rectangular, but semi-oval. A semi-oval cross-sectional shape of the first core portion 30 and the second core portion 50 is closer to the substantially oval cross-sectional shape of the heating profile of the strip-shaped susceptor 40. Advantageously, this allows for saving liquid aerosol-forming substrate and flavoring materials in the first core portion 30 and the second core portion 50 and thus leads to a more efficient usage of the liquid aerosol-forming substrate and flavoring materials in the first core portion 30 and the second core portion 50.

[0169] The inductively heatable aerosol-forming rods according to the present invention may be manufactured using a method and a manufacturing device 1000 as schematically illustrated in FIG. 4.

[0170] The manufacturing device 1000 comprises a sleeve material supply 200 configured for supplying a sleeve material 201 to a sleeve-forming device 130 of a shaping device 100. The sleeve material supply 200 comprises an unwinding unit 210 for unwinding the sleeve material 201 provided on a bobbin 211. Downstream of the unwinding unit 210, the manufacturing device 1000 further comprises a buffer 220 for buffering the sleeve material 201, a treatment unit 230 for pre-treating the sleeve material 201, a tensioning unit 600 for adjusting the tension of the sleeve material 201 and dispensing unit 700. In the present embodiment, the treatment unit 230 may be configured for physical treatment of the sleeve material 201, for example, for crimping the sleeve material 201. Crimping the sleeve material 201 may facilitate formation of the sleeve portion in the shaping device 100. The dispensing unit 700 may be used for applying at least one of fluids, granules, particles and powders to the sleeve material, for example a fluid flavoring material.

[0171] With regard to the first core portion and the second core portion of the aerosol-forming rod, the manufacturing device 1000 comprises a first core material supply 300 and a second core material supply 500 which are configured for supplying a first core material 301 and a second core material 501, respectively, to a common core-forming device 130 of the shaping device 100. Each of the first core material supply 300 and the second core material supply 500 comprises an unwinding unit 310, 510 for unwinding the respective core material 301, 501 that is provided on a respective bobbin 311, 511.

[0172] Likewise, the manufacturing device 1000 comprises a susceptor supply 400 that is configured for supplying a susceptor profile 401 to longitudinal guide 140 of the shaping device 100. The susceptor supply 400 comprises an unwinding unit 410 for unwinding the susceptor profile 401 that is provided on a bobbin 411.

[0173] Downstream of the unwinding unit 410, the manufacturing device 1000 further comprises a treatment unit 430 for pre-treating the susceptor profile 401. In the present embodiment, the treatment unit 430 is configured to create a plurality of perforations in the susceptor profile 401 and to stretch the perforated susceptor profile 401 at least along a first direction such as to create an expanded susceptor profile which comprises a plurality of openings 441 originating from the plurality of perforations. A example of such an expanded susceptor profile 401 is shown in FIG. 7.

[0174] To obtain an aerosol-forming rod 10 as shown in FIG. 1 and FIG. 2, the sleeve material 201, the first core material 301, the second core material 501 and the susceptor profile 401 need to be combined and shaped such as to create a first core portion, a second core portion, a susceptor and a sleeve portion arranged around the first and second core portions and the susceptor. For this, the manufacturing device 1000 comprises a shaping device 100 which is arranged downstream of the aforementioned units and into which the sleeve material 201, the first core material 301, the second core material 501 and the susceptor profile 401 are simultaneously fed, as shown in FIG. 4.

[0175] FIG. 5 shows details of the shaping device 100 used for the manufacturing of an aerosol-forming rod as shown in FIG. 1 and FIG. 2. The lower part of FIG. 5 is a longitudinal cross-section through the device 100 and the upper part of FIG. 5 comprises three transverse cross-sections through the device 100 at three different longitudinal positions as indicated in the lower part of FIG. 5. According to the invention, the shaping device 100 comprises a sleeve forming device 120, a common core-forming device 130 and a longitudinal susceptor guide 140, wherein the common core-forming device 130 realizes (all-in-one) a first core-forming device and a second core-forming device for gathering the first core material 301 and the second core material 501 into a first continuous core strand and a second continuous core strand, respectively.

[0176] In the present embodiment, the common core-forming device 130 comprises an inner funnel 131 which is configured for gathering the first core material 301 and the second core material 501 into a first continuous core strand and a second continuous core strand, respectively, such that upon passing through the common core-forming device 301 the first continuous core strand has a cross-sectional shape corresponding to a cross-sectional shape of the cylindrical first core portion of the aerosol-forming rod to be manufactured, and the second continuous core strand has a cross-sectional shape corresponding to a cross-sectional shape of the cylindrical second core portion of the aerosol-forming rod to be manufactured. In correspondence with the radial position of the first core portion and the second core portion in the aerosol-forming rod, the center axis of the inner funnel is coaxial to a longitudinal center axis 107 of the shaping device 100.

[0177] The longitudinal guide 140 is configured for arranging the continuous susceptor profile 401 relative to the first core strand 130 and the second core strand 150 such as to laterally abut the continuous core strand in a non-bonded manner upon passing through the inner funnel 131 of the common core-forming device 130. In the present embodiment, the longitudinal guide 140 comprises a guiding tube 141 which is arranged coaxially to the longitudinal center axis 107 of the shaping device 100 and extends downstream into an upstream section of the common core-forming device 130. In the upstream section of the common core-forming device 130, the first core material and the second core material is already pre-gathered. The upstream section of the common core-forming device 130 has a length 109 which is about 30 percent of the total length 108 of the common core-forming device 130.

[0178] As can be seen in the upper part of FIG. 5, the guiding tube 141 has a rectangular cross-section which tapers towards the downstream end of the guiding tube 141, where the rectangular cross-section substantially corresponds to the rectangular cross-section of the susceptor profile. The guiding tube 141 forms a guiding channel 143 which the susceptor profile 401 is fed into, such as to be initially separated from the first core material 301 and the second core material 501 in the upstream section of the common core-forming device 130. At the downstream end of the longitudinal guide 140, the susceptor profile 401 is released from guidance allowing the susceptor profile 401 to come together with the pre-gathered core material at a position corresponding to its pre-defined position in the final aerosol-forming rod.

[0179] For gathering the sleeve material into a continuous sleeve strand around the continuous core strand and the susceptor, the shaping device 100 comprises a sleeve forming device 120. Like the common core-forming device 130, the sleeve forming device 120 also comprises a funnel, which is an outer funnel 121 arranged around at least a downstream section of the core-forming device. In the present embodiment, the outer funnel 121 even extends along the entire length of the core-forming device 130 such that the inner funnel 131 is completely received within the outer funnel 121. A downstream end of the common core-forming device 130 opens out into a downstream section of the sleeve-forming device, where the sleeve material is already pre-gathered. Thus, at the downstream end of the common core-forming device 130, the first continuous core strand and the second continuous core strand as well as the susceptor profile—which is sandwiched between the first core strand and the second core strand—are released into pre-gathered sleeve material. This may be advantageous with regard to positional stability of the core portions and the susceptor at their desired positions in the final aerosol-forming rod.

[0180] As further shown in FIG. 5, the shaping device 100 further comprises two guiding fins 180 arranged at an inner surface of the outer funnel 121 of the sleeve-forming device 120. These guiding fins 180 are configured to guide the sleeve material towards the downstream end of the sleeve-forming device 120. Advantageously, the guiding fins 180 may help to reduce undesired heating of the sleeve-forming device and the core-forming device during the sleeve-forming process that may occur due to friction between the different parts of the shaping device 100 and the sleeve material.

[0181] To adjust the position of the first core portion, the second core portion and the susceptor within the aerosol-forming rod, the shaping device 100 comprise a first translation stage 171 and a second translation stage 172 operatively coupled to the longitudinal guide 140 and the common core-forming device 130, respectively. In the present invention, the first translation stage 171 is configured to adjust an axial position of the longitudinal guide 140 relative to the common core-forming device 130 along the longitudinal center axis 107 of the shaping device 100. This enables to adjust the axial position where the susceptor profile 401 comes together with the pre-gathered first core material and the pre-gathered second core material. The second translation stage 172 is configured to adjust the position of the common core-forming device 130 relative to the sleeve-forming device 120 along three directions, namely, a first direction being parallel to the longitudinal center axis 107 of the shaping device 100, a second direction perpendicular being to the longitudinal center axis 107 and third direction being perpendicular to the second direction and to the longitudinal center axis 107. By this, the position where the susceptor and the first continuous core strand and the second continuous core strand and come together with the pre-gathered sleeve material may be controlled in three dimensions.

[0182] At the downstream end of the sleeve-forming device 120, the entity of the continuous sleeve strand core strand, the susceptor profile, the first continuous core strand and the second continuous core strand leaves the shaping device 100. Within the entity, the continuous sleeve strand has a cross-sectional shape corresponding to a cross-sectional shape of the sleeve portion, the first continuous core strand and the second continuous core strand have a cross-sectional shape corresponding to a cross-sectional shape of the first core portion and the second core portion, respectively, and the susceptor is abuttingly sandwiched the continuous core strand.

[0183] Referring again to FIG. 4, the manufacturing device 100 further comprises a rod-forming device 800 downstream of the shaping device 100 which is configured for forming the entity of the first continuous core strand, the second continuous core strand, the susceptor profile and the continuous sleeve strand into a continuous aerosol-forming rod strand. As described above but not shown in FIG. 4, the rod-forming device 800 may comprise a garniture tape which interacts with the at least one semi-funnel to form the final rod shape. The garniture tape may further support a wrapper supplied by a wrapper supply (not shown) into an upstream end of the rod-forming device 800. In operation, the wrapper is automatically wrapped around the substrate web as the latter is progressively gathered around the sleeve portion such that a continuous aerosol-forming rod strand being entirely surrounded by a wrapper leaves the rod-forming device 800 at its downstream end.

[0184] Downstream of the rod-forming device, the manufacturing device 1000 may further comprise a cutting device 900 for cutting continuous aerosol-forming rod strand into individual inductively heatable aerosol-forming rods according to the present invention.

[0185] FIG. 6 shows details of the shaping device 100 used for the manufacturing of an aerosol-forming rod as shown in FIG. 3. The device is similar to the device shown in FIG. 5. Therefore, identical or similar features are denoted with identical reference numerals. The device 100 according to FIG. 6 differs from the device 100 according to FIG. 5 by the cross-sectional shape of the common core-forming device 130, which is not rectangular, but oval such as to allow shaping of the first core material and the second core material into a first core strand and a second core strand each of which has a semi-oval cross-sectional shape as shown in FIG. 3.