METHOD AND APPARATUS FOR MANUFACTURING INDUCTIVELY HEATABLE AEROSOL-FORMING RODS

Abstract

The present invention relates to a method for manufacturing inductively heatable aerosol-forming rods (100). The method comprises supplying a first substrate web (31) and a second substrate web (32) separately to a continuous multiple-stage rod-forming process which comprises at least a first and a subsequent second stage. The method further comprises supplying a continuous susceptor profile (20) to the rod-forming process such that the susceptor profile passes through at least the second stage. Furthermore, the method comprises passing the first and second substrate web separately through the first stage. Thereby, the first and the second substrate web are separately pre-gathered transversely with regard to a respective transport direction of each of the substrate web through the first stage. The method further comprises passing the susceptor profile and the pre-gathered substrate webs through the second stage. Thereby, the separately pre-gathered substrate webs are jointly gathered into a rod shape around the susceptor profile. The invention further relates to a multi-stage rod-forming device (10) comprising at least a first stage (11) and a second stage (12) downstream of the first stage. The first stage is configured for separately pre-gathering a first and a second substrate web (31, 32) respectively as each of them passes through the first stage. The second stage is configured for jointly gathering the pre-gathered substrate webs into a rod shape around a susceptor profile (20) as the susceptor profile and the pre-gathered substrate webs pass through the second stage.

Claims

1. Method for manufacturing inductively heatable aerosol-forming rods, the method comprising the steps of: supplying a first substrate web and a second substrate web separately to a continuous multiple-stage rod-forming process, the multiple-stage rod-forming process including at least a first and a subsequent second stage; supplying a continuous susceptor profile to the rod-forming process such as to pass through at least the second stage; passing the first and second substrate web separately through the first stage, thereby separately pre-gathering the first and second substrate web in a transverse direction with respect to a respective transport direction of the first and second substrate web through the first stage; and passing the susceptor profile and the pre-gathered first and second substrate web through the second stage, thereby jointly gathering the pre-gathered first and second substrate web into a rod shape around the susceptor profile.

2. The method according to claim 1, wherein the step of passing the susceptor profile through the second stage comprises passing the susceptor profile through the second stage at least partially along a center axis of the second stage.

3. The method according to claim 1, wherein supplying the susceptor profile to the rod-forming process comprises supplying the susceptor profile such as to enter the second stage between the first and the second substrate web.

4. The method according to claim 1, wherein supplying the susceptor profile to the rod-forming process comprises supplying the susceptor profile such as to pass through the first stage without contact to the first and the second substrate web prior to passing through the second stage.

5. The method according to claim 1, further comprising the step of longitudinally guiding the susceptor profile along at least an upstream section of the second stage.

6. Apparatus for manufacturing inductively heatable aerosol-forming rods, the apparatus comprising: a multi-stage rod-forming device comprising at least a first stage and a second stage, wherein the second stage is located downstream of the first stage, wherein the first stage is configured for separately pre-gathering a first substrate web and a second substrate web in a transverse direction with respect to the transport directions of the first and second substrate web through the first stage, as each of the first and second web passes through the first stage, and wherein the second stage is configured for jointly gathering the pre-gathered first substrate web and second substrate web into a rod shape around a susceptor profile as the susceptor profile and the pre-gathered first substrate web and second substrate web pass through the second stage; a susceptor supply configured for supplying the continuous susceptor to the rod-forming device such as to pass through at least the second stage; and a substrate supply configured for supplying the first substrate web and second substrate web to the rod-forming device.

7. The apparatus according to claim 6, wherein a downstream end of the first stage extends into an upstream end of the second stage.

8. The apparatus according to claim 6, wherein the first stage comprises a first funnel for pre-gathering the first web and a second funnel for pre-gathering the second web.

9. The apparatus according to claim 8, wherein the first and second funnel are positioned laterally offset at opposite sides with regard to a center axis of the second stage of the rod-forming device.

10. The apparatus according to claim 6, wherein the first stage comprises a pre-gathering element having a first convex guide surface converging towards the second stage for pre-gathering the first substrate web as passing over the first guide surface towards the second stage and a second convex guide surface converging towards the second stage for pre-gathering the second substrate web as passing over the second guide surface towards the second stage.

11. The apparatus according to claim 10, wherein the pre-gathering element comprises a sleeve having a tapered outside surface including the first and second guide surfaces.

12. The apparatus according to claim 10, wherein the pre-gathering element comprises at least one separating fin extending between the first and second convex guide surface towards the second stage.

13. The apparatus according to claim 6, wherein the second stage of the rod-forming device comprises at least one of a funnel or a semi-funnel.

14. The apparatus according to claim 6, further comprising a longitudinal guide for guiding the continuous susceptor profile along a center axis of the second stage through at least an upstream section of the second stage.

15. The apparatus according to claim 14, wherein the longitudinal guide extends through the entire first stage and at least through the upstream section of the second stage.

Description

[0085] The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0086] FIG. 1 schematically illustrates an exemplary embodiment of an apparatus according to the invention comprising a multi-stage rod-forming device having a first and a second stage;

[0087] FIG. 2 is a schematic cross-sectional view of an aerosol-forming rod manufactured by using the method and the apparatus according to the invention;

[0088] FIG. 3 schematically illustrates an alternative embodiment of the first stage of the rod-forming device according to FIG. 1;

[0089] FIG. 4 schematically illustrates a modification of the rod-forming device according to FIG. 1; and

[0090] FIG. 5 schematically illustrates another modification the rod-forming device according to FIG. 1.

[0091] FIG. 1 schematically illustrates an exemplary embodiment of an apparatus 1 according to the invention. The apparatus 1 is configured for manufacturing aerosol-forming rods 100 comprising a susceptor profile 20 in the center which a first and a second substrate web 31, 32, each including an aerosol-forming substrate, are coaxially gathered around. The apparatus 1 as shown in FIG. 1 is particularly configured for performing the method according to the invention and as described herein.

[0092] Main component of the apparatus 1 is a rod-forming device 10 configured for gathering the first substrate web 31 and the second substrate web 32 around the susceptor profile 20 coaxially to a center axis 80 of the rod-forming device 10, thus resulting in the final rod shape. The rod-forming process is a continuous process. That is, the first and second substrate webs 31, 32 and the susceptor profile 20 enter and pass the rod-forming device 10 as continuous materials. Accordingly, gathering of the first and second substrate webs 31, 32 around the susceptor profile 20 occurs as the substrate webs 31, 32 and the susceptor profile 20 together pass through the rod-forming device 10. The center axis 80 also defines a transport line through the rod-forming device 10.

[0093] Upstream of the rod-forming device 10, the apparatus 1 comprises a first and a second substrate supply 35, 36 (generally symbolized by the upper and lower arrow on the right side of FIG. 1) for supplying the first and the second substrate web 31, 32 downstream towards the upstream end 13 (entrance) of the rod-forming device 10. The first and second substrate webs 31, 32 preferably are continuous tobacco webs, for example cast leaf. Each one of the first and second substrate web 31, 32 enters the rod-forming device 10 as substantially flat material. As can be seen from FIG. 1, the first substrate web 31 is supplied such as to enter the rod-forming device 10 below the center axis 80, whereas the second substrate web 32 is supplied such as to enter the rod-forming device 10 above the center axis 80. In particular, the flat sides of each one of the first and second substrate web 31, 32 are arranged substantially horizontally when entering the rod-forming device 10. As, described above, supplying the substrate material in form of a first and a second substrate web 31, 32 advantageously allows for pre-distributing the substrate material around the susceptor profile 20. This in turn positively affects the subsequent step of gathering the substrate material around the susceptor profile 20, in particular substantially symmetrically.

[0094] The apparatus 1 further comprises a susceptor supply 21 (generally symbolized by the central arrow on the right side of FIG. 1) for supplying the continuous susceptor profile 20 downstream towards the rod-forming device 10. In the present embodiment, the susceptor profile 20 is a continuous sheet 20 of a susceptor material having a rectangular cross-section, such as a continuous band made of ferromagnetic stainless steel. The susceptor profile 20 may be provided, for example, on a bobbin (not shown) which is part of the susceptor supply 21. The susceptor profile 20 is unwound from the bobbin and supplied towards the center axis 80 upstream of the rod-forming device 10.

[0095] According to the invention, the rod-forming device 10 is a multi-stage rod-forming device 10. In the present embodiment, the device 10 comprises a first stage 11 and a second stage 12, the latter being located downstream of the first stage 11. The first stage 11 is configured for separately pre-gathering the first substrate web and the second substrate web 31, 32 in a transverse direction with respect to the transport directions of the first and second substrate web 31, 32 through the first stage 11 as both substrate webs 31, 32 pass through the first stage 11. The second stage 12 is configured for jointly gathering the pre-gathered first and second substrate webs 31, 32 into a rod shape around the susceptor profile 20 as the susceptor profile 20 and the pre-gathered substrate webs 31, 32 pass through the second stage 12.

[0096] In the present embodiment of the rod-forming device 10, the first stage 11 comprises a first and a second pre-gathering unit 71, 72. The first pre-gathering unit 71 is arranged below the center axis 80 and configured for pre-gathering the first substrate web 31 in a transverse direction with respect to its transport direction through the first pre-gathering unit 71. Likewise, the second pre-gathering unit 72 is arranged above the center axis 80 and configured for pre-gathering the second substrate web 32 in a transverse direction with respect to its transport direction through the second pre-gathering unit 72. As can be seen from FIG. 1, each of the first and second pre-gathering unit 71, 72 comprises a frustum-shaped funnel 71, 72. A circular inner cross-sectional profile of the respective funnel 71, 72 continuously decreases from an upstream end 13 of the first stage 11 towards a downstream end 14 of the first stage 11. Each funnel 71, 72 pre-gathers the respective substrate web 31, 32 transversely with respect to its length extension. Upon having passed the first stage 11, the first and the second substrate webs 31, 32 are pre-gathered but have not yet assumed the final rod shape. As described further above, pre-gathering of the first and second substrate web 31, 32 causes friction effects and a resistance to compression of the substrate material to be less pronounced during the actual rod-forming process in the second stage 12. Advantageously, this not only increases the overall efficiency of the rod-forming process but also facilitates an accurate positioning of the susceptor 20 at a pre-defined position within the aerosol-forming rod. In particular, the pre-gathered substrate webs 31, 32 provide a supporting embedding of the susceptor profile in the second stage 12. Furthermore, pre-gathering also reduces the risk of plastic deformations of the susceptor profile 20.

[0097] As can be further seen from FIG. 1, the susceptor profile 20 is supplied to the rod-forming device 10 such as to enter and pass both, the first and the second stage 11, 12 of the rod-forming device 10, along the center axis 80. Due to the central positioning, the susceptor profile 20 is accurately placed at its desired final position within the aerosol-generating rod 100, that is, coaxially to, in particular on-axis with a center axis of the aerosol-generating rod 100. In particular, the susceptor profile 20 is positioned along the center axis 80 having the flat sides of the susceptor profile 20 arranged substantially horizontally. Also, the susceptor profile 20 is positioned on-axis with regard to the center axis 80 of the rod-forming device 10. That is, a longitudinal axis of the susceptor profile 20 extending through a center of mass or a geometric center of the susceptor profile 20 is coaxial to the center axis 80 of the rod-forming device 10.

[0098] Since the susceptor profile 20 also enters and passes the first stage 11 along the center axis 80, the susceptor profile 20 is already pre-positioned on-axis prior to entering the second stage 12, that is, prior to getting into contact with the pre-gathered first and second substrate web 31, 32. Thus, the pre-positioned susceptor profile 20 defines a physical center for the rod-forming process which the first and the second substrate web 31, 32 are coaxially gathered around. Advantageously, this causes the rod-forming process to be reliable and reproducible with regard to an accurate center position of the susceptor within the surrounding substrate.

[0099] As described above, the first and second substrate web 31, 32 are supplied such as to pass the first stage 11 and to enter the second stage 12 below and above the center axis 80, respectively. Thus, each of the pre-gathered first and second substrate web 31, 32 enters the second stage 12 laterally to the susceptor profile 20. Advantageously, this ensures that there is little or essentially no divergence of the susceptor profile 20 from its pre-defined on-axis position upon entering the second stage. In particular, each of the pre-gathered first and second substrate web 31, 32 enters the second stage 12 from below or above, respectively, towards the susceptor profile 20, that is, at an angle greater than zero degrees to the center axis 80, for example at an angle of 5 degrees. In particular, having the pre-gathered first substrate web 31 arranged substantially horizontally below the susceptor profile 20 advantageously supports the susceptor profile 20 when passing through the second stage 12. This also facilitates to keep a stable position of the susceptor profile 20 along the center axis 80.

[0100] In order to prevent the susceptor profile 20 from being displaced from the center axis 80 as passing through the rod-forming device 10, the apparatus 1 further comprises a longitudinal guide 23 for guiding the susceptor profile 20 along the center axis 80. In the present embodiment, the longitudinal guide is a guiding tube 23 extending coaxially to the center axis 80 through the entire first stage 12 in between the first and second pre-gathering units 71, 72.

[0101] The guiding tube 23 also extends in the upstream direction beyond an upstream end 13 of the first stage 11. That is, an upstream end 24 of the guiding tube 23 is positioned upstream of the funnels 71, 72. Advantageously, this supports an accurate pre-positioning and guiding of the susceptor profile 20 along the center axis 80 prior to entering the rod-forming device 10.

[0102] Advantageously, the guiding tube 23 ends at a position downstream of the first stage 11 where the susceptor profile 20 preferably is at least partially surrounded by the pre-gathered first and second substrate webs 31, 32. In the present embodiment as shown in FIG. 1, a downstream end 25 of the guiding tube 23 is positioned adjacent to an upstream end 15 of the second stage 12.

[0103] The second stage 12 of the rod-forming device is configured for completing the step of gathering the pre-gathered first and second substrate web 31, 32 coaxially around the susceptor profile 20 into the final rod shape. In the present embodiment, the second stage 12 comprises a semi-funnel 73 arranged above the center axis 80 which comprises a rod-forming concave surface having a C-shaped cross-section. The C-shaped cross-section progressively decreases in size downstream from the upstream end 15 to a downstream end 16 of the second stage 12. The second stage 12 further comprises a conveyor belt 17, in the present embodiment a garniture tape 17, which interacts with the semi-funnel 73 to form the final rod shape. For this, the garniture tape 17 progressively takes a cross-sectional U-shape as it runs along the second stage 12 downstream below the center axis 80. In operation, the U-shaped garniture tape 17 in combination with the semi-funnel 72 gathers the pre-gathered first and second substrate web 31, 32 coaxially around the susceptor profile 20 into the final circular rod shape.

[0104] In addition, a paper wrapper 51 is supplied from a wrapper supply 50 into the upstream end 15 of the second stage 12. As can be seen from FIG. 1, the wrapper 51 is supported on a top surface of the garniture tape 17 which faces the center axis 80. Thus, in operation the wrapper 51 is automatically wrapped around the first and second substrate web 31, 32 as the latter are progressively gathered around the susceptor profile 20. Preferably, glue is added to at least one longitudinal edge of the wrapper 51 for connecting both longitudinal edges of the wrapper upon being wrapped around the rod-shaped material of the first and second substrate web 31, 32. Thus, the wrapper 51 serves to stabilize the final rod shape. For adding glue and connecting the longitudinal edges of the wrapper 51, the rod-forming device 10 according to the present embodiment comprises a folding and compressing device 18 downstream of the second stage 12.

[0105] At a downstream end 19 of the overall rod-forming device 10, the device 10 provides a continuous aerosol-forming rod 100 having the final rod-shape in which the first and the second substrate webs 31, 32 are fully gathered around the susceptor profile 20 and entirely surround by the wrapper 51.

[0106] Downstream of the rod-forming device 10, the apparatus 1 further comprises a cutting device 60 for cutting the continuous rod 100 into inductively heatable aerosol-forming rod segments 101.

[0107] FIG. 2 shows a cross-sectional view of a continuous aerosol-forming rod 100 or rod segment 101, respectively, manufactured using the apparatus and the method as illustrated in FIG. 1 and described before. The circular cross-section of the rod shape may have a diameter between about 4 millimeters and about 10 millimeters, in particular, between about 5 millimeters and about 8 millimeters. The rectangular shape of the susceptor profile 20 preferably has a width extension between about 2 millimeters and about 8 millimeters, in particular between about 3 millimeters and about 5 millimeters, and a thickness extension between about 0.03 millimeter and about 0.15 millimeter, more preferably between about 0.05 millimeter and about 0.09 millimeter.

[0108] Due to the fact that the substrate material is supplied and processed in two parts, that is, in the form of the first and second substrate web 31, 32, the substrate material is substantially symmetrically gathered around both flat sides of the susceptors profile 20. As a result, the susceptor profile 20 is positioned substantially symmetrically with regard to a center 81 of the circular cross-section of the rod-shape, as can be seen in FIG. 2. This position is preferred with regard to a homogeneous, in particular symmetric and reproducible heat distribution in the aerosol-generating rod. Thus, heat generated in the susceptor profile 20 symmetrically dissipates into the circumferential periphery of the susceptor profile 20 allowing to homogeneously heat-up the aerosol-forming substrate of the substrate webs 31, 32 gathered around.

[0109] FIG. 3 shows an alternative embodiment of the first stage 11 of the rod-forming device 10. Instead of the funnel-like first and second pre-gathering units 71, 72, the first stage 11 of the embodiment shown in FIG. 3 comprises a pre-gathering element 74. The pre-gathering element 74 comprises a sleeve having a tapered downstream portion 78. An outside surface of the tapered downstream portion 78 includes a first convex guide surface 75 and a second convex guide surface 76 which correspond to the outside surface of the lower and upper half of the downstream portion 78 of the sleeve. Each guide of the surfaces 74, 75 converges towards a downstream end 14 of the first stage 11 and is bowed outward with respect to the center axis 80 of the gathering process. The first guide surface 75 is arranged and configured for pre-gathering the first substrate web 31 as passing over the first guide surface 31 towards the second stage 12. Likewise, the second guide surface 76 is arranged and configured for pre-gathering the second substrate web 32 as passing over the second guide surface 76 towards the second stage 12. Advantageously, the first and second convex guide surface 75, 76 cause the first and second substrate web 31, 32 to be pre-shaped such as to have a curved or half-moon cross-sectional profile which in turn facilitates the subsequent step of gathering both substrate webs 31, 32 around the susceptor profile 20 in the second stage 12. The sleeve configuration of the pre-gathering element 74 advantageously enables the susceptor profile 20 to pass through the pre-gathering element 74 between the first and second convex guide surface 75, 76, in particular without contact to the first and second substrate web 31, 32. This further facilitates the susceptor profile 20 to enter the second stage 12 between the first and second substrate web 31, 32.

[0110] Furthermore, the pre-gathering element 74 comprises a separating fin 77 extending alongside the downstream portion 78 between the first and second convex guide surface 75, 76 towards the second stage 12. In particular, the separating fin 77 extends in a length direction of the pre-gathering element 74, substantially along a transport direction of the first and second substrate web 31, 32 as passing over the first and second guide surface 75, 76 towards the second stage 12. The separating fin 77 facilitates to pre-gather the first and second substrate web 31, 32 transversely with respect to their respective transport direction. Furthermore, the separating fin 77 serves to keep the first and second substrate web 31, 32 separated from each other before entering into the second stage 12. Of course, the pre-gathering element 74 may also comprises two separating fins extending at opposite sides of the pre-gathering element 74.

[0111] FIG. 4 shows a modification of the rod-forming device 10 according to FIG. 1 which concerns the transition from the first stage 11 to the second stage 12. According to this embodiment, the first stage 11 comprises a funnel-like first and second pre-gathering unit 71, 72 as described above with regard to FIG. 1. Likewise, a longitudinal guide 23 extends between both gathering units 71, 72 along a center axis 80 of the rod-forming device 10. In addition to the semi-funnel 73 and the garniture tape 17 (not shown in FIG. 4), the second stage 12 comprises a global funnel 79 upstream of the semi-funnel 73 and the garniture tape 17. As can be seen in FIG. 4, a downstream end of the funnel-like first and second pre-gathering units 71, 72, that is a downstream end 14 of the first stage 11, extends into an upstream end of the global funnel 79, that is, into an upstream end 15 of the second stage 12. Advantageously, this nested arrangement of the first and second stage 11, 12 provides a compact design of the apparatus 1. Moreover, the global funnel 79 provides a smooth transition for the susceptor profile and the pre-gathered first and second substrate web when passing from the first stage 11 to the second stage 12. In particular, an upper portion of the global funnel 79 may continuously merge into the semi-funnel 77 of the second stage 12 (not shown). Alternatively, the global funnel 79 may be part of the first stage 11. Of course, the rod-forming forming device 10 according to FIG. 3 comprising the alternative embodiment of the first stage 11 may also comprise a global funnel 79.

[0112] FIG. 5 illustrates another modification of the rod-forming device 10 according to FIG. 1 which concerns the longitudinal guide 23. FIG. 5 shows a top view of the lower part of the second stage 12 according to FIG. 1 (without the semi-funnel 73). According to this embodiment, a downstream end 25 of the longitudinal guide 23 is positioned in a downstream section 92 of the second stage 12. There, the gathering process of the pre-gathered first and second substrate web 31, 32 is further progressed such that the pre-gathered first and second substrate web 31, 32 are preferably in contact with each other. As a consequence, the susceptor profile 20 is at least partially surrounded and supported by the first and second substrate web 31, 32 which thus stabilize the position of the susceptor profile 20. Furthermore, any pressure and friction effects of the first and second substrate webs 31, 32 on the susceptor profile 20 are substantially symmetric in the downstream section 92. Due to this symmetry, possible pressure and friction effects are substantially balanced and thus do not adversely affect the shape and position of the susceptor profile 20. Vice versa, upstream of the downstream section 92, in particular in a upstream section 91 of the second stage 12, the longitudinal guide 23 advantageously protects the susceptor profile 20 from any asymmetric and thus unbalanced pressure and friction effects of the first and second substrate webs 31, 32. As can be further seen in FIG. 5, the garniture tape 17 has progressively taken a constant cross-sectional U-shape in the downstream section 92. Of course, the rod-forming forming device 10 according to FIG. 3 comprising the alternative embodiment of the first stage 11 may also comprise a longitudinal guide 23 having a downstream end 25 positioned in a downstream section 92 of the second stage 12.

[0113] Any surface of the first and second stage 11, 12 which gets into contact with the first and second substrate web 31, that is, the inner surface of the funnels 71, 72, the semi-funnel 73, the global funnel 79 and the first and second guide surface 75, 76 of the pre-gathering element 74, preferably comprises a low friction surface material, for example, a plastic or polished metal surface. This reduces the risk of material weakening or even rupture of the first and second substrate web 31, 32. Furthermore, less friction also reduces vibrations of the first and second substrate 31, 32 as passing through the first and second stage 11, 12.