METHOD AND APPARATUS FOR MANUFACTURING A CRIMPED SHEET OF MATERIAL

Abstract

The invention relates to an apparatus (1) for crimping a sheet of material (7), the apparatus (1) comprising: a first and a second facing crimping rollers (4,5) defining a first and a second rotation axis, wherein at least one of the first and second crimping roller (4,5) includes: a plurality of ridges (9), each ridge (9) defining a first and a second flank (16) and a tip, the first or the second flank (16) forming a flank angle (15) with a radial direction passing through the tip, the flank angle (15) being comprised between about 8 degrees and about 10 degrees.

Claims

1-14. (canceled)

15. Apparatus for crimping a sheet of material, the apparatus comprising: a first and a second facing crimping rollers defining a first and a second rotation axis, wherein at least one of the first and second crimping roller includes: a plurality of ridges, each ridge defining a first and a second flank and a tip, the first or the second flank forming a flank angle with a radial direction passing through the tip, wherein all ridges of the plurality form a flank angle comprised between about 4 degrees and about 20 degrees.

16. Apparatus according to claim 15, wherein the ridges are distanced one to the other with a constant pitch.

17. Apparatus according to claim 15, wherein said ridges have all substantially the same amplitude.

18. Apparatus according to claim 15, wherein the first and second flank are symmetrical with respect to the radial direction passing through the tip.

19. Apparatus according to claim 15, wherein the first or the second roller is realized in metal.

20. Apparatus according to claim 15, wherein the other of the first and second crimping roller includes a plurality of ridges, the first and second rollers being arranged such that the ridges of the first roller substantially interleave with the ridges of the second roller.

21. A method of manufacturing a crimped sheet for an aerosol-generating article, the method comprising the steps of: feeding a substantially continuous sheet of material to a set of crimping rollers, the set of crimping rollers comprising a first roller and a second roller, at least one of the first or second roller including a plurality of ridges; and crimping the substantially continuous web to form the crimped web by feeding the substantially continuous sheet between the first and second rollers in a longitudinal direction of the sheet of material such that the ridges of the first or second rollers apply a plurality of crimp corrugations to the substantially continuous sheet of material; wherein the ridges in the first or second roller defines a first and a second flank and a tip, the first or the second flank forming a flank angle with a radial direction passing through the tip, wherein the flank angle formed by all ridges of the first or second roller is comprised between about 4 degrees and about 20 degrees.

22. A method of manufacturing an aerosol-generating article component, the method comprising the steps of: manufacturing a crimped sheet according to claim 21; gathering the crimped sheet to form a continuous rod; and cutting the continuous rod into a plurality of rod-shaped components, each rod-shaped component having a gathered crimped sheet formed from a cut portion of the crimped sheet, the crimp corrugations of the crimped sheet defining a plurality of channels in the rod-shaped component.

23. The method according to claim 21, wherein the sheet of material is one of: a sheet of alkaloid containing material, a plastic sheet or a sheet including cellulose.

24. The method according to claim 23, wherein the sheet of alkaloid containing material includes a homogenised tobacco sheet.

25. A crimped sheet realized according to the method of claim 21.

26. The crimped sheet according to claim 25, wherein the crimped sheet of material is one of: a sheet of alkaloid containing material, a plastic sheet or a sheet including cellulose.

27. The crimped sheet according to claim 26, wherein the sheet of alkaloid containing material includes a homogenised tobacco sheet.

28. An aerosol generating article comprising a portion of the crimped sheet of claim 25.

Description

[0072] Further advantages of the invention will become apparent from the detailed description thereof with non-limiting reference to the appended drawings:

[0073] FIG. 1 is a schematic lateral view of an apparatus for manufacturing of a crimped sheet of material;

[0074] FIG. 2 is a schematic front view of the crimping pair of rollers and the nip they are forming for crimping the material; and

[0075] FIG. 3 is a schematic partial view of the crimping teeths' geometry of the crimping pair of rollers.

[0076] In FIG. 1, the basic layout for an apparatus 1 for manufacturing a crimped sheet of material 7 for an aerosol-generating device is shown in a schematic lateral view.

[0077] The raw material is supplied by means of a first coil, namely a supply coil 2. On the supply coil 2, an endless sheet of a flat and thin layer of material 3 to be crimped using the apparatus 1 is provided. The material 3 may be a homogenised tobacco sheet or a plastic sheet or a cellulose-type sheet, on which some type of tobacco-like flavour compound may be applied. It is to be understood that the sheet of material 3 that is wound up on coil 2 is strictly speaking not endless. However, the overall length of the sheet of material can be several hundred metres and is therefore much longer than its width. Furthermore, it is possible that a handover mechanism between two consecutive supply coils 2 (not shown) is provided so that a continuous crimping process will be possible.

[0078] The sheet is coiled down from the supply coil 2 and enters the main part of the apparatus 1, where the processing of the material 3 is performed. The material 3 is fed into the apparatus 1 as a single, flat layer of material 3. The processing of the flat layer of material 3 is done in a nip 6 which is formed between the upper roller 4 and the roller 5 by an appropriate placement of the two rollers 4, 5 at a certain distance. The width of the nip 6 is roughly in the range of the thickness of the entering layer of material 3. The width of the nip 6 is usually defined as the distance to a neighbouring surface portion of the other roller 4, 5 in a direction that is essentially perpendicular to the surface portion in question. Depending on the current necessities of the processing process, the width of the nip 6 is typically slightly smaller than the thickness of the entering layer of material 3, so that the entering layer of material 3 is slightly compressed in the nip 6. Thus, a traction force can be applied to the flat layer of material 3 by the rollers 4, 5.

[0079] In the presently shown embodiment, both the upper roller 4 and the lower roller 5 show an outer surface 11 with a corresponding surface structure (see also FIGS. 2 and 3). Namely, ridges 9 of the first of the rollers 4 will partially protrude into corresponding, neighbouring troughs 10 of the second of the rollers 5 and vice versa. This will be explained in detail in the following, in particular with reference to FIGS. 2 and 3.

[0080] Due to the design of the rollers 4, 5, in particular due to the design of the outer surfaces 11 of the rollers 4, 5, the sheet of material 3 that passes through the nip 6 will be corrugated. The corrugated sheet 7 of material leaves the processing nip 6 at its other side. The corrugated sheet 7 is fed to the product coil 8, on which the processed and corrugated sheet 7 of material is wound up. The corrugation of the corrugated sheet 7 is shown in FIG. 1 in an exaggerated way for illustrative purposes.

[0081] Albeit in the present example the outer surfaces 11 of both rollers 4, 5 show a fully structured outer surface 11, it has to be understood that it is also possible that only one of the rollers 4, 5 shows a structured outer surface 11; that one or both of the rollers 4, 5 show an only partially structured outer surface 11 (meaning that a part of the outer surface 11 of the respective roller(s) will show an essentially unstructured outer surface); and the like.

[0082] In FIG. 2, the nip 6 that is formed by upper roller 4 and lower roller 5 as seen by the entering sheet of material 3 is shown in more detail. In other words, the view of FIG. 2 is perpendicular to the view of FIG. 1. As can be seen in FIG. 2 particularly well, the upper rollers 4, 5 both show a structured surface 11, comprising an alternating series of ridges 9 and troughs 10, where the pitch between two successive ridges 9 or the pitch between two successive troughs 10 remains essentially constant over the full width of the respective roller 4, 5. Furthermore, the amplitude of the surface structure, that is the difference in radius of the roller 4, 5 between the tops of the ridges 9 and the bottoms of the troughs 10 remains essentially constant over the full width of the respective roller 4, 5 as well.

[0083] As can be further seen in FIG. 2 and in more detail in FIG. 3, the arrangement of the ridges 9 and the troughs 10 is slightly offset on the two neighbouring rollers 4, 5, so that the ridges 9 and the troughs 10 partially intermesh with each other. In particular, usually the offset between the structure of the outer surface of the rollers 4, 5 is essentially equivalent to about half of the pitch 12 between two successive ridges 9 or two successive troughs 10.

[0084] Depending on the design of the rollers 4, 5, the sheet of material 7 that is leaving the nip 6 (i.e. the sheet of material 7 that is processed by apparatus 1 as indicated in FIG. 1) will show a corresponding surface structure.

[0085] It should be understood that the surface structure 11 and the placement of the rollers 4, 5 as shown in the present embodiment is only according to a typical example.

[0086] Different embodiments are likewise possible. For example, it is possible as well that only one of the rollers (for example the upper roller 4) shows a surface structure 11, comprising ridges 9 and troughs 10, while the other roller (for example the lower roller 5) shows an essentially unstructured outer surface. Similarly, the surface structure 11 on the two rollers 4, 5 may be different as well. As a nonlimiting example: the amplitudes 14 of surface structures 11 of the two rollers 4, 5 may be chosen differently.

[0087] In FIG. 3 the geometry of the surface structure 11 is shown in more detail. Only for completeness, it should be mentioned that due to the scale of FIG. 3 only a very limited number of ridges 9 and troughs 10 is shown. In reality, the number of ridges 9 and troughs 10 will be usually significantly larger. Furthermore, only those parts of the outer surfaces 11 of the neighbouring rollers 4, 5 that are forming the nip 6 can be seen in FIG. 3 due to the scale chosen.

[0088] The pitch 12 of the ridges 9 (the peaks or tips), which is the distance between two successive ridges 9 as measured in the axial direction of the corresponding roller 4, 5, is presently chosen to be about 1 millimetre. Since the surface structure 11, in particular the ridges 9 and the troughs 10 are arranged symmetrically, the distance 13 between a ridge 9 and the neighbouring trough 10, as seen in the axial direction of the respective roller 4, 5, will be half of the pitch 12, and will therefore be about 0.5 millimetres. In the presently shown example, the amplitude 14, which is the distance between a ridge 9 and a trough 10 as seen in in the radial direction of the respective roller 4, 5 is presently 1 millimetre as well. Therefore, the slant distance between a ridge 9 (peak) and the neighbouring trough 10 will be correspondingly larger. Presently, it can be calculated by the theorem of Pythagoras and reads about {square root over (1.sup.2+0.52)}=1.12 (indicated lengths in millimetres).

[0089] Furthermore, the offset between the two surface structures 11 in the axial direction can be seen in FIG. 3 as well. Presently, the offset is chosen to be half of the pitch 12 between two neighbouring ridge 9, which is about 0.5 millimetres according to the present geometry. This way, a ridge 9 of the upper roller 4 will be axially aligned with a trough 10 of the lower roller 5 and vice versa.

[0090] According to an important aspect of the present invention, the flank angle 15, which is the angle that is enclosed between a flank 16, neighbouring a ridge 9, and a line that is arranged in a radial direction of the respective roller 4, 5 that is passing the tip of the ridge 9 will have a certain value. Due to the presently symmetrical design of the rollers' 4, 5 surfaces 11, the angle that is enclosed between the two flanks 16 that are neighbouring a ridge 9, is about twice the flank angle 15.

[0091] In the presently shown example (where FIG. 3 is not drawn to scale), the flank angle 15 is chosen to be about 9 degrees. In particular, a certain variation is possible. In particular, the flank angle 15 may be chosen to be between about 4 degrees and about 20 degrees. According to a preferred embodiment, the flank angle 15 may be chosen to be between about 8 degrees and about 10 degrees. However, different upper and lower limits are possible (including a combination of the indicated limiting values), for example about 5 degrees, about 6 degrees or about 7 degrees (in particular as a lower limit) or about 11 degrees, about 12 degrees, about 13 degrees, about 14 degrees, about 15 degrees, about 16 degrees, about 17 degrees, about 18 degrees or about 19 degrees (in particular as an upper limit).

[0092] It is particularly preferred that the flanks 16 will show a certain length that is straight, which means that it does not show a local surface curvature. The ridges 9 and the troughs 10 are preferably rounded essentially following a circular shape. Of course, it is to be understood that a different design is possible as well. In particular, the surface curve can be a spline or something else as well. In this case (but possibly in other cases as well), as the defining point of the flank 16, where one leg of the flank angle 15 is measured, the inflection point of the respective curve can be chosen (the line that is pointing in a radial direction may form the other leg of the flank angle 15). However, different definitions of the flank angle 15 are likewise possible.