METHOD AND APPARATUS FOR MANUFACTURING A CRIMPED WEB

Abstract

An apparatus for and a method of manufacturing a crimped web for an aerosol-generating article is provided, including feeding a substantially continuous web to a set of crimping rollers including a first roller and a second roller, each of which is corrugated across at least a portion of a width thereof; and crimping the web by feeding the web between the rollers in a longitudinal direction of the web such that corrugations of the rollers apply a plurality of longitudinally extending and substantially parallel crimp corrugations to the web, wherein pitch values of the corrugations of one or both of the rollers vary across the width thereof such that pitch values of the crimp corrugations vary across a width of the crimped web.

Claims

1.-16. (canceled)

17. A method of manufacturing a crimped web for an aerosol-generating article, the method comprising: feeding a substantially continuous web to a set of crimping rollers, the set of crimping rollers comprising a first roller and a second roller, each of which is corrugated across at least a portion of a width thereof, the first and second rollers being arranged such that corrugations of the first roller substantially interleave with corrugations of the second roller; and crimping the substantially continuous web to form the crimped web by feeding the substantially continuous web between the first and second rollers in a longitudinal direction of the web such that the corrugations of the first and second rollers apply a plurality of longitudinally extending and substantially parallel crimp corrugations to the substantially continuous web, wherein pitch values of the corrugations of one or both of the first and second rollers vary across the width of the rollers such that pitch values of the crimp corrugations vary across a width of the crimped web.

18. A method of manufacturing an aerosol-generating article component, the method comprising: manufacturing a crimped web according to claim 17; gathering the crimped web to form a continuous rod; and cutting the continuous rod into a plurality of rod-shaped components, each rod-shaped component of said plurality having a gathered crimped sheet formed from a cut portion of the crimped web, the crimp corrugations of the gathered crimped sheet defining a plurality of axial channels in said each rod-shaped component.

19. An apparatus for manufacturing a crimped web for an aerosol-generating article, the apparatus comprising: a set of crimping rollers comprising a first roller and a second roller, each of which is corrugated across at least a portion of a width thereof, wherein the first and second rollers are arranged such that corrugations of the first roller substantially interleave with corrugations of the second roller, and wherein pitch values of the corrugations of one or both of the first and second rollers vary across the width of the rollers.

20. The method according to claim 17, wherein at least 10 percent of the corrugations of the first and second rollers have a pitch value that differs from a pitch value of at least one directly adjacent corrugation.

21. The method according to claim 17, wherein pitch values of substantially all of the corrugations of the first and second rollers vary from about 0.5 mm to about 1.7 mm.

22. The method according to claim 17, wherein each of at least some of the corrugations of the first and second rollers has an amplitude value that differs from an amplitude value of at least one directly adjacent corrugation of said corrugations.

23. The method according to claim 22, wherein amplitude values of the corrugations of the first and second rollers vary from about 0.1 mm to about 1.5 mm.

24. The method according to claim 17, wherein each of at least some of the corrugations of the first and second rollers has a corrugation angle that differs from a corrugation angle of at least one directly adjacent corrugation of said corrugations.

25. The method according to claim 24, wherein corrugation angles of the corrugations of the first and second rollers vary from about 30 degrees to about 90 degrees.

26. A crimped sheet for at least one of an aerosol-cooling element and an aerosol-forming substrate for an aerosol-generating article, the crimped sheet comprising: a plurality of substantially parallel crimp corrugations extending in a longitudinal direction of the crimped sheet, wherein pitch values of the substantially parallel crimp corrugations vary across a width of the crimped sheet.

27. The crimped sheet according to claim 26, wherein each of at least some of the substantially parallel crimp corrugations has an amplitude value that differs from an amplitude value of at least one directly adjacent crimp corrugation of said corrugations.

28. The crimped sheet according to claim 26, wherein each of at least some of the substantially parallel crimp corrugations has a corrugation angle that differs from a corrugation angle of at least one directly adjacent crimp corrugation of said corrugations.

29. The crimped sheet according to claim 26, further comprising a sheet material selected from a group including a metallic foil, a polymeric sheet, paper, a homogenised tobacco material, and a combination thereof.

30. An aerosol-cooling element for an aerosol-generating article, the aerosol-cooling element comprising: a rod formed from a gathered crimped sheet according to claim 26, wherein the plurality of substantially parallel crimp corrugations of the gathered crimped sheet define a plurality of axial channels in the rod.

31. An aerosol-forming substrate for an aerosol-generating article, the aerosol-forming substrate comprising: a rod formed from a gathered crimped sheet according to claim 26, wherein the plurality of substantially parallel crimp corrugations define a plurality of axial channels in the rod.

32. An aerosol-generating article comprising an aerosol-cooling element according to claim 30.

33. An aerosol-generating article comprising an aerosol-forming substrate according to claim 31.

Description

[0077] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0078] FIG. 1 is a schematic side view of an apparatus for manufacturing a crimped web according to the present invention;

[0079] FIG. 2 is a cross-sectional view of first and second rollers of the apparatus of FIG. 1;

[0080] FIG. 3 is an enlarged view of detail A in FIG. 2 for a first embodiment of first roller;

[0081] FIG. 4 is an enlarged view of detail B in FIG. 2 for a first embodiment of second roller;

[0082] FIG. 5 is a cross-sectional view of a portion of a first embodiment of crimped sheet, formed using the rollers of FIGS. 3 and 4;

[0083] FIG. 6 is an enlarged view of detail A in FIG. 2 for a second embodiment of first roller;

[0084] FIG. 7 is an enlarged view of detail B in FIG. 2 for a second embodiment of second roller;

[0085] FIG. 8 is a cross-sectional view of a portion of a second embodiment of crimped sheet, formed using the rollers of FIGS. 6 and 7;

[0086] FIG. 9A is a schematic cross-sectional side view of an aerosol-generating article according to the present invention; and

[0087] FIG. 9B is a schematic cross-sectional view of the aerosol-generating article of FIG. 9A taken through the line 9B-9B in FIG. 9A.

[0088] FIG. 1 shows apparatus 100 for manufacturing a crimped web. The apparatus 100 comprises, among other components, a set of crimping rollers 102 including a first roller and a second roller, each of which is corrugated across its width. The set of crimping rollers 102 is arranged such that the corrugations of the first roller substantially interleave with the corrugations of the second roller. The apparatus 100 also comprises a lateral sheet cutting mechanism 104, a bobbin 106 of sheet web material 108, such as a web of polylactide acid, paper, or homogenized tobacco material, a drive and brake mechanism 110, and a tensioning mechanism 112. Control electronics 114 are provided to control the apparatus 100 during operation.

[0089] In use, the drive and brake mechanism 110 feeds the web 108 in a longitudinal direction from the bobbin 106 to the set of crimping rollers 102 via the lateral web cutting mechanism 104, which cuts the web to the required width. The tensioning mechanism 112 ensures that the web 108 is fed to the set of crimping rollers 102 at the desired tension. The crimping rollers 102 force the web 108 between the interleaved corrugations of the first and second rollers to apply a plurality of longitudinally extending crimp corrugations to the web 108. In this manner, the web 108 is deformed by the crimping rollers 102 to form a crimped web 116. The crimped web 116 can then be gathered together and used to form an aerosol-cooling element or an aerosol-forming substrate for an aerosol-generating article, as discussed below. For example, the crimped web 116 can be gathered together to form a continuous rod which is subsequently cut into a plurality of rod-shaped components, each having a gathered crimped sheet formed from a cut portion of the crimped web.

[0090] FIG. 2 shows a cross-sectional view of the set of crimping rollers 102. The set of crimping rollers 102 comprises a first roller 120 and a second roller 122, each of which is corrugated across its width 1201 in a corrugation zone 124. In this example, the corrugation zone 124 extends around the entire circumference of each roller and extends along substantially the entire width 1201 of each roller. Alternatively, one or both of the rollers could be corrugated across its width around only a portion of its circumference or along only a portion of its length, or around only a portion of its circumference and along only a portion of its length. The first and second rollers 120, 122 are arranged such that their axes are substantially parallel and such that their corrugations are substantially interleaved. The distance 1202 between the axes of the first and second rollers 120, 124 can be controlled to control the clearance between the corrugations of the first and second rollers 120, 122 and thus the amplitude of the crimp corrugations applied to a web passed between the set of rollers 102.

[0091] FIG. 3 shows an enlarged view of a corrugated portion of a first embodiment of first roller 300. As shown, on the surface of the first roller 300 are a plurality of corrugations 310 formed from alternating peaks 312 and troughs 314 joined by corrugation flanks 316. The pitch values of the corrugations 310 vary across the width of the first roller 300. In this example, the corrugation zone of the first roller 300 is formed from a repeating pattern of different corrugations. The repeating pattern is three corrugations wide and consists of a first corrugation 3101 with a pitch value 3106, followed by a second corrugation 3102 with a pitch value 3107, followed by a third corrugation 3103 with a pitch value 3108. The repeating pattern thus has width 3105, which is equal to the sum of the first pitch value 3106, second pitch value 3107 and third pitch value 3108. Pitch values 3106, 3107 and 3108 are different. Thus, the pitch value of each corrugation in the repeating pattern differs from the pitch value of each directly adjacent corrugation and the pitch values of the corrugations vary across the width of the first roller 300. In alternative examples, the corrugation zone could be formed from an alternating pattern of different corrugations, such as a first corrugation alternating with second and third corrugations in a first, second, first, third pattern.

[0092] In this example, the three different corrugations 3101 to 3103 have substantially the same amplitude value 3110. To vary the pitch values, the corrugations angles of corrugations 3101 to 3103 are different. In particular, the corrugation angle 3121 of the first corrugation 3101 is greater than the corrugation angle 3122 of the second corrugation 3102, which in turn is greater than the corrugation angle 3123 of the third corrugation 3103. Thus, the corrugation angle of each corrugation differs from the corrugation angle of each directly adjacent corrugation.

[0093] The corrugation angle of a given corrugation is defined by the angle between its corrugation flanks. The corrugation flanks may be disposed at the same angle from the radial direction of the roller, or at a different angle. In this example of first roller, the angles formed by the corrugation flanks of each corrugation and the radial direction, or the “flank angles”, are substantially the same, such that each corrugation is symmetrical about its peak in the radial direction. For each corrugation, both of the flank angles thus equate to approximately half of the corrugation angle. As the corrugation angles 3121, 3122 and 3123 are different, so to are the three flank angles 3131, 3133 and 3135 of the corrugations 3101, 3102 and 3103. Consequently, the troughs between directly adjacent corrugations are asymmetrical about the radial direction.

[0094] FIG. 4 shows an enlarged view of a corrugated portion of a first embodiment of second roller 400. As with the first roller 300, on the surface of the second roller 400 are a plurality of corrugations 410 formed from alternating peaks 412 and troughs 414 joined by corrugation flanks 416. The pitch values of the corrugations 410 vary across the width of the second roller 400. As with the first roller 300, the corrugation zone of the second roller 400 is formed from a repeating pattern consisting of first corrugation 4101 with a pitch value 4106, followed by a second corrugation 4102 with a pitch value 4107, followed by a third corrugation 4103 with a pitch value 4108. The repeating pattern thus has width 4105, which is equal to the sum of the first pitch value 4106, the second pitch value 4107, and the third pitch value 4108. Pitch values 4106, 4107 and 4108 are different. Thus, the pitch value of each corrugation in the repeating pattern differs from the pitch value of each directly adjacent corrugation and the pitch values of the corrugations vary across the width of the second roller 400. In alternative examples, the corrugation zone could be formed from an alternating pattern of different corrugations, such as a first corrugation alternating with second and third corrugations in a first, second, first, third pattern.

[0095] The widths 3105, 4105 of the repeating patterns of both of the first and second rollers 300, 400 are substantially the same. This allows the corrugations of the first and second rollers 300, 400 to be aligned.

[0096] As with the first roller 300, the three different corrugations 4101 to 4103 of the second roller 400 have substantially the same amplitude value 4110. In this example, amplitude value 4110 is substantially the same as the amplitude value 3110 of the corrugations of the first roller 300, although this is not essential. To vary the pitch values, the corrugations angles of corrugations 4101 to 4103 are different. In particular, the corrugation angle 4121 of the first corrugation 4101 is greater than the corrugation angle 4122 of the second corrugation 4102, which in turn is greater than the corrugation angle 4123 of the third corrugation 4103. Thus, the corrugation angle of each corrugation differs from the corrugation angle of each directly adjacent corrugation.

[0097] The corrugation angle of a given corrugation is defined by the angle between its corrugation flanks. The corrugation flanks may be disposed at the same angle from the radial direction of the roller, or at a different angle. In this example of second roller, the two flank angles of each corrugation are different, such that each corrugation is asymmetrical about its peak in the radial direction. As shown in FIG. 4, the corrugation angle 4121 of the first corrugation 4101 is formed from different flank angles 4131 and 4132, the corrugation angle 4122 of the second corrugation 4102 is formed from different flank angles 4133 and 4134, and the corrugation angle 4123 of the third corrugation 4103 is formed from different flank angles 4135 and 4136. In this example, although the flank angles of a given corrugation are different, the flank angles of directly adjacent flanks of directly adjacent corrugations are the same. Consequently, the troughs between directly adjacent corrugations are symmetrical about the radial direction. This allows the troughs of the corrugations on the second roller 400 to interleave with the peaks of the corrugations on the first roller 300, which are also symmetrical about the radial direction. In addition, preferably the flank angles of the opposing corrugation flanks on the first and second rollers are substantially the same, such that the clearance between opposing corrugation flanks of the first and second rollers 300, 400 is substantially constant. This allows the formation of a crimped web having well defined crimp corrugations and a substantially constant nominal thickness.

[0098] In one particular embodiment, the various parameters have the following values:

First Roller:

[0099]

TABLE-US-00001 First roller: 3106 = 1.3 mm 3107 = 1.1 mm 3108 = 0.9 mm 3105 = 3.3 mm 3110 = 0.6 mm 3121 = 74 degrees 3122 = 65 degrees 3123 = 56 degrees 3131 = 37 degrees 3133 = 32.5 degrees 3135 = 27.5 degrees

Second Roller:

[0100]

TABLE-US-00002 Second roller: 4106 = 1.2 mm 4107 = 1.0 mm 4108 = 1.1 mm 4105 = 3.3 mm 4110 = 0.6 mm 4121 = 69.5 degrees 4122 = 60 degrees 4123 = 64.5 degrees 4132 = 37 degrees 4131 = 32.5 degrees 4134 = 32.5 degrees 4133 = 27.5 degrees 4136 = 27.5 degrees 4135 = 37 degrees

[0101] FIG. 5 shows a cross-sectional view of a portion of a first embodiment of crimped sheet 500, formed using the first and second rollers 300, 400 of FIGS. 3 and 4. The crimped sheet 500 has a nominal thickness 5001 and a plurality of substantially parallel crimp corrugations 510 extending along the length of the sheet 500 (in the direction perpendicular to the plane of FIG. 5). The crimp corrugations 510 are formed from alternating peaks 512 and troughs 514 joined by corrugation flanks 516. The shape and dimensions of the crimp corrugations 510 corresponds to the shape and dimensions of the first and second rollers 300, 400. In particular, the shape of the peaks 512 corresponds to the shape of the peaks of the corrugations of the second roller 400 and the shape of the troughs 514 corresponds to the shape of the peaks of the corrugations of the first roller 300.

[0102] Thus, as with the corrugations of the first and second rollers, the crimp corrugations 510 of the crimped sheet 500 are arranged in a repeating pattern consisting of a first crimp corrugation 5101 with a pitch value 5106, followed by a second crimp corrugation 5102 with a pitch value 5107, followed by a third crimp corrugation 5103 with a pitch value 5108. The repeating pattern thus has width 5105, which is equal to the sum of the first pitch value 5106, the second pitch value 5107, and the third pitch value 5108 and is the same as the pattern width of the corrugations on the first and second rollers 300, 400. Pitch values 5106, 5107 and 5108 are different from each other. Thus, the pitch value of each crimp corrugation differs from the pitch value of each directly adjacent crimp corrugation and the pitch values of the crimp corrugations vary across the width of the sheet 500.

[0103] As with the corrugations of the first and second rollers 300, 400, the three different crimp corrugations 5101 to 5103 of the sheet 500 have substantially the same amplitude value 5110. However, the corrugation angles 5121 to 5123 of the three different crimp corrugations 510 are different. As the shape of the peaks 512 and troughs 514 correspond respectively to the shape of the peaks of the second and first rollers 300, 400, each crimp corrugation 510 is asymmetrical about its peak, and the troughs between directly adjacent crimp corrugations are each symmetrical. In this example, the corrugation angles 5121 to 5123 and flank angles 5131, 5132, 5133, 5134, 5135 and 5136 of the crimp corrugations 5101 to 5103 are the same as those of the corrugations of the second roller 400.

[0104] As the pitch values of the crimp corrugations vary across the width of the sheet 500, the crimp corrugations of the crimped sheet are less likely to nest against each other when the crimped sheet 500 is gathered to form a rod for use in an aerosol-generating article. As a result, the axial channels formed by the crimp corrugations when gathered in the rod are more uniform in size and distribution across the area of the rod.

[0105] In one particular embodiment, the various parameters have the following values:

Crimped Sheet:

[0106]

TABLE-US-00003 Crimped sheet: 5106 = 1.2 mm 5107 = 1.0 mm 5108 = 1.1 mm 5109 = 3.3 mm 5121 = 69.5 degrees 5122 = 60 degrees 5123 = 64.5 degrees 5131 = 37 degrees 5132 = 32.5 degrees 5133 = 32.5 degrees 5134 = 27.5 degrees 5135 = 27.5 degrees 5136 = 37 degrees 5110 = 50 micrometres

[0107] FIG. 6 shows an enlarged view of a corrugated portion of a second embodiment of first roller 600. As shown, on the surface of the first roller 600 are a plurality of corrugations 610 formed from alternating peaks 612 and troughs 614 joined by corrugation flanks 616. The pitch values of the corrugations 610 vary across the width of the first roller 600. In this example, the corrugation zone of the first roller 600 is formed from a repeating pattern of different corrugations. The repeating pattern is four corrugations wide and consists of a first corrugation 6101 with a pitch value 6106, followed by a second corrugation 6102 with a pitch value 6107, followed by a third corrugation 6103 with a pitch value 6108, followed by a fourth corrugation 6104 with a pitch value 6109. The pattern thus has width 6105, which is equal to the sum of the first pitch value 6106, the second pitch value 6107, the third pitch value 6108, and the fourth pitch value 6109. In alternative examples, the corrugation zone could be formed from an alternating pattern of different corrugations, such as a first corrugation alternating with second, third and fourth corrugations in a first, second, first, third, first, fourth pattern.

[0108] In this example, the corrugation angles 6121 to 6124 of the four different corrugations 6101 to 6104 are substantially the same. The flank angles 6131 on either side of each corrugation peak are also substantially the same and equate to approximately half of the corrugation angle.

[0109] Although the corrugation angles of the four different corrugations 6101 to 6104 are substantially the same, the amplitude values are not. First, second, third, and fourth corrugations 6101 to 6104 have amplitude values 6111 to 6114, respectively. As mentioned previously, the amplitude value refers to the height of a corrugation from its peak to the deepest point of the deepest directly adjacent trough. For the first roller 600, the radial distance from the centre of the roller 600 to the peaks 612 of the corrugations 610 is substantially the same across the width of the roller. However, the radial distance from the centre of the roller to the troughs 614 of the corrugations 610, or the “depth” of the troughs 614, varies across the width of the roller 600. In particular, the depth of the troughs 614 varies such that the amplitude values 6111, 6114 and pitch values 6106, 6109 of the first and fourth corrugations 6101 and 6104 are substantially the same, as are the amplitude values 6112, 6113 and pitch values 6107, 6108 of the second and third corrugations 6102 and 6103. The first and fourth amplitude values 6111, 6114 and pitch values 6106, 6109 are greater than the second and third amplitude values 6112, 6113 and pitch values 6107, 6108. Thus, the amplitude value of each corrugation differs from the amplitude value of at least one directly adjacent corrugation. In this manner, the amplitude values and, thus, the pitch values of the corrugations vary across the width of the first roller 600.

[0110] FIG. 7 shows an enlarged view of a corrugated portion of a second embodiment of second roller 700. As with the first roller 600, on the surface of the second roller 700 are a plurality of corrugations 710 formed from alternating peaks 712 and troughs 714 joined by corrugation flanks 716. The pitch values of the corrugations 710 vary across the width of the second roller 700. In this example, the corrugation zone of the second roller 700 is formed from a repeating pattern of different corrugations. The repeating pattern is four corrugations wide and consists of a first corrugation 7101 with a first pitch value 7106, followed by a second corrugation 7102 with a second pitch value 7107, followed by a third corrugation 7103 with a third pitch value 7108, followed by a fourth corrugation 7104 with a fourth pitch angle 7109. The repeating pattern thus has a width P, which is equal to the sum of the first pitch value 7106, the second pitch value 7107, the third pitch value 7108, and the fourth pitch value 7109. In alternative examples, the corrugation zone could be formed from an alternating pattern of different corrugations, such as a first corrugation alternating with second, third and fourth corrugations in a first, second, first, third, first, fourth pattern.

[0111] In this example, the corrugation angles 7121 to 7124 of the four different corrugations 7101 to 7104 are substantially the same. The flank angles 7131 on either side of each corrugation peak are also substantially the same and equate to approximately half of the corrugation angle.

[0112] Although the corrugation angles of the four different corrugations 7101 to 7104 are substantially the same, the amplitude values are not. First, second, third, and fourth corrugations 7101 to 7104 have amplitude values 7111 to 7114, respectively. As mentioned previously, the amplitude value refers to the height of a corrugation from its peak to the deepest point of the deepest directly adjacent trough. Unlike the first roller 600, the radial distance from the centre of the second roller 700 to the troughs 714 of the corrugations 710, or the “depth” of the troughs 714, is substantially the same across the width of the roller, whereas the radial distance from the centre of the roller to the peaks 712 of the corrugations 710 varies across the width of the roller.

[0113] In particular, the radial distance from the centre of the roller to the peaks 712 of the corrugations 710 is such that the amplitude value 7111 of the first corrugation 7101 is greater than the amplitude value 7112 of the second corrugation 7102, which is greater than the amplitude value 7113 of the third corrugation 7103. The amplitude value 7114 of the fourth corrugation 7104 is substantially the same as the amplitude value 7112 of the second corrugation 7102. Consequently, the pitch value 7106 of the first corrugation 7101 is greater than the pitch value 7107 of the second corrugation 7102, which is the same as the pitch value 7109 of the fourth corrugation 7104, both of which are greater than the pitch value 7108 of the third corrugation 7103. Thus, the amplitude value of each corrugation differs from the amplitude value of at least one directly adjacent corrugation. In this manner, the amplitude values and, thus, the pitch values of the corrugations vary across the width of the second roller 700.

[0114] Preferably, the widths of the repeating patterns of both of the first and second rollers 600, 700 are substantially the same. This allows the corrugations of the first and second rollers 600, 700 to be aligned. In addition, preferably the corrugation angles and flank angles of the corrugations of both rollers are also the same, such that the corrugations interleave and the clearance between opposing corrugation flanks of the first and second rollers 600, 700 is substantially constant. This allows the formation of a crimped web having well defined crimp corrugations and a substantially constant nominal thickness.

[0115] In one particular embodiment, the various parameters have the following values:

First Roller:

[0116]

TABLE-US-00004 First roller: 6106 = 1.2 mm 6107 = 1.0 mm 6108 = 1.0 mm 6109 = 1.2 mm 6105 = 4.4 mm 6111 = 0.83 mm 6112 = 0.55 mm 6113 = 0.55 mm 6114 = 0.73 mm 6121 = 60 degrees 6122 = 60 degrees 6123 = 60 degrees 6124 = 60 degrees 6131 = 30 degrees

Second Roller:

[0117]

TABLE-US-00005 Second roller: 7106 = 1.3 mm 7107 = 1.1 mm 7108 = 0.9 mm 7109 = 1.1 mm 7105 = 4.4 mm 7111 = 0.83 mm 7112 = 0.73 mm 7113 = 0.55 mm 7114 = 0.73 mm 7121 = 60 degrees 7122 = 60 degrees 7123 = 60 degrees 7124 = 60 degrees 7131 = 30 degrees

[0118] FIG. 8 shows a cross-sectional view of a portion of a second embodiment of crimped sheet 800, formed using the first and second rollers 600, 700 of FIGS. 6 and 7. The crimped sheet 800 has a nominal thickness 8001 and a plurality of substantially parallel crimp corrugations 810 extending along the length of the sheet 800 (in the direction perpendicular to the plane of FIG. 8). The crimp corrugations 810 are formed from alternating peaks 812 and troughs 814 joined by corrugation flanks 816. The shape and dimensions of the crimp corrugations 810 corresponds to the shape and dimensions of the first and second rollers 600, 700. In particular, the shape of the peaks 812 corresponds to that of the peaks of the corrugations of the second roller 700 and the shape of the troughs 814 corresponds to the shape of the peaks of the corrugations of the first roller 600.

[0119] Thus, as with the corrugations of the first and second rollers, the crimp corrugations 810 of the crimped sheet 800 are arranged in a repeating pattern of four different crimp corrugations. The repeating pattern is four crimp corrugations wide and consists of a first crimp corrugation 8101 with a pitch value 8106, followed by a second crimp corrugation 8102 with a pitch value 8107, followed by a third crimp corrugation 8103 with a pitch value 8108, followed by a fourth crimp corrugation 8104 with a pitch value 8109. The pattern thus has width 8105, which is equal to the sum of the first pitch value 8106, the second pitch value 8107, the third pitch value 8108, and the fourth pitch value 8109 and is equal to the pattern width of the corrugations on the first and second rollers 600, 700. In alternative examples, the corrugation zone could be formed from an alternating pattern of different corrugations, such as a first corrugation alternating with second, third and fourth corrugations in a first, second, first, third, first, fourth pattern.

[0120] In this example, the four different crimp corrugations 8101 to 8104 have substantially the same corrugation angle 8121 and flank angles 8131 as each other. The flank angles 8131 on either side of each crimp corrugation peak are also substantially the same as each other and equate to approximately half of the corrugation angle 8121.

[0121] Although the corrugation angles of the four different crimp corrugations 8101 to 8104 are substantially the same, the amplitude values are not. First, second, third, and fourth crimp corrugations 8101 to 8104 have amplitude values 8111 to 8114, respectively. The amplitude value 8111 of the first crimp corrugation 8101 is greater than the amplitude value 8112 of the second crimp corrugation 8102, which is greater than the amplitude value 8113 of the third crimp corrugation 8103. The amplitude value 8114 of the fourth crimp corrugation 8104 is substantially the same as the amplitude value 8112 of the second crimp corrugation 8102. Consequently, the pitch value 8106 of the first crimp corrugation 8101 is greater than the pitch value 8107 of the second crimp corrugation 8102, which is the same as the pitch value 8109 of the fourth crimp corrugation 8104, both of which are greater than the pitch value 8108 of the third crimp corrugation 8103. Thus, the amplitude value of each crimp corrugation differs from the amplitude value of both directly adjacent crimp corrugations. In this manner, the amplitude values and, thus, the pitch values of the crimp corrugations vary across the width of the sheet. Consequently, the crimp corrugations of the crimped sheet 800 are less likely to nest against each other when it is gathered to form a rod for use in an aerosol-generating article. As a result, the axial channels formed by the crimp corrugations in the rod are more uniform in size and distribution across the area of the rod.

[0122] In one particular embodiment, the various parameters have the following values:

Crimped Sheet:

[0123]

TABLE-US-00006 Crimped sheet: 8106 = 1.3 mm 8107 = 1.1 mm 8108 = 0.9 mm 8109 = 1.1 mm 8105 = 4.4 mm 8111 = 0.83 mm 8112 = 0.73 mm 8113 = 0.55 mm 8114 = 0.73 mm 8121 = 60 degrees 8131 = 30 degrees 8001 = 50 micrometres

[0124] FIGS. 9A and 9B illustrate an aerosol-generating article 900 according to an embodiment. The aerosol-generating article 900 comprises four elements, an aerosol-forming substrate 920, a hollow cellulose acetate tube 930, an aerosol-cooling element 940, and a mouthpiece filter 950. These four elements are arranged sequentially and in coaxial alignment and are assembled by a cigarette paper 960 to form a rod 910. The rod 910 has a mouth-end 912, and a distal end 914 located at the opposite end of the rod 910 to the mouth end 914. Elements located between the mouth-end 912 and the distal end 914 can be described as being upstream of the mouth-end 912 or, alternatively, downstream of the distal end 914.

[0125] When assembled, the rod 910 is about 45 millimetres in length and has a diameter of about 7 millimetres.

[0126] The aerosol-forming substrate 920 is located upstream of the hollow tube 930 and extends to the distal end 914 of the rod 910. In one embodiment, the aerosol-forming substrate 920 comprises a bundle of crimped cast-leaf tobacco wrapped in a filter paper (not shown) to form a plug. The cast-leaf tobacco includes additives, including glycerine as an aerosol-forming additive. In another embodiment, the aerosol-forming substrate comprises a gathered, crimped sheet of homogenised tobacco material.

[0127] The hollow acetate tube 930 is located immediately downstream of the aerosol-forming substrate 920 and is formed from cellulose acetate. One function of the tube 930 is to locate the aerosol-forming substrate 920 towards the distal end 914 of the rod 910 so that it can be contacted with a heating element. The tube 930 acts to prevent the aerosol-forming substrate 920 from being forced along the rod 910 towards the aerosol-cooling element 940 when a heating element is inserted into the aerosol-forming substrate 920. The tube 930 also acts as a spacer element to space the aerosol-cooling element 940 from the aerosol-forming substrate 920.

[0128] The aerosol-cooling element 940 has a length of about 18 mm and a diameter of about 7 mm. In this example, the aerosol-cooling element 940 is formed from a gathered, crimped sheet 942 having a plurality of substantially parallel crimp corrugations extending in a longitudinal direction of the sheet, wherein the pitch values of the crimp corrugations vary across the width of the sheet and wherein the crimp corrugations define a plurality of axial channels 944 that extend along the length of the aerosol-cooling element 940. In one embodiment, the aerosol-cooling element 940 is formed from a sheet of polylactic acid having a nominal thickness of 50 micrometres.

[0129] Porosity is defined herein as a measure of unfilled space in a rod including an aerosol-cooling element consistent with the one discussed herein. For example, if a diameter of the rod 910 was 50 percent unfilled by the element 940, the porosity would be 50 percent. Likewise, a rod would have a porosity of 100 percent if the inner diameter was completely unfilled and a porosity of 0 percent if completely filled. The porosity may be calculated using known methods. When the aerosol-cooling element 940 is formed from a sheet of material having a thickness (t) and a width (w) the cross-sectional area presented by an edge of the sheet is given by the width multiplied by the thickness. In a specific embodiment of a sheet material having a thickness of 50 micrometers and width of 230 millimetres, the cross-sectional area is approximately 1.15×10̂-5 metres squared (this may be denoted the first area). Assuming a diameter of the rod that will eventually enclose the material is 7 mm, the area of unfilled space may be calculated as approximately 3.85×10̂-5 metres squared (this may be denoted the second area).

[0130] The crimped sheet 942 comprising the aerosol-cooling element 940 is then gathered and confined within the inner diameter of the rod. The ratio of the first and second area based on the above examples is approximately 0.30. This ratio is multiplied by 100 and the quotient is subtracted from 100 percent to arrive at the porosity, which is approximately 70 percent for the specific figures given here. Clearly, the thickness and width of a sheet material may be varied. Likewise, the diameter of the rod may be varied.

[0131] As shown in FIG. 9B, the crimp corrugations of the crimped and gathered sheet 942 define a plurality of axial channels 944 in the aerosol-cooling element 940. Depending on the degree to which the crimp corrugations of adjacent portions of gathered sheet cluster together, the size and distribution of the axial channels 944 can vary across the area of aerosol-cooling element 940, leading to areas of high local porosity 946 and areas of low local porosity 948, as shown in FIG. 9B. Due to the fact that the pitch values of the crimped sheet 942 vary across the width of the sheet, the crimp corrugations of adjacent portions of sheet are less likely to align and nest together and the distribution of the axial channels 944 is more uniform.

[0132] It will now be obvious to one of ordinary skill in the art that with a known thickness and width of a material, in addition to the inner diameter of the rod, the porosity can be calculated in the above manner. Accordingly, where a sheet of material has a known thickness and length, and is crimped and gathered along the length, the space filled by the material can be determined. The unfilled space may be calculated, for example, by taking the inner diameter of the rod. The porosity or unfilled space within the rod can then be calculated as a percentage of the total area of space within the rod from these calculations.

[0133] The crimped and gathered sheet of polylactic acid is wrapped within a filter paper 941 to form the aerosol-cooling element 940.

[0134] The mouthpiece filter 950 is a conventional mouthpiece filter formed from cellulose acetate, and having a length of about 4.5 millimetres.

[0135] The four elements identified above are assembled by being tightly wrapped within a paper 960. The paper 960 in this specific embodiment is a conventional cigarette paper having standard properties. The interference between the paper 960 and each of the elements locates the elements and defines the rod 910 of the aerosol-generating article 900.

[0136] Although the specific embodiment described above and illustrated in FIGS. 9A and 9B has four elements assembled in a cigarette paper, it is clear than an aerosol-generating article may have additional elements or fewer elements.

[0137] An aerosol-generating article as illustrated in FIGS. 9A and 9B is designed to engage with an aerosol-generating device (not shown) in order to be consumed. Such an aerosol-generating device includes means for heating the aerosol-forming substrate 920 to a sufficient temperature to form an aerosol. Typically, the aerosol-generating device may comprise a heating element that surrounds the aerosol-generating article adjacent to the aerosol-forming substrate 920, or a heating element that is inserted into the aerosol-forming substrate 920.

[0138] Once engaged with an aerosol-generating device, the aerosol-forming substrate 920 may be heated to a temperature of about 375 degrees Celsius. At this temperature, volatile compounds are evolved from the aerosol-forming substrate 920. These compounds condense to form an aerosol, which passes through the rod 910.

[0139] The aerosol is drawn through the aerosol-cooling element 940. As the aerosol passes thorough the aerosol-cooling element 940, the temperature of the aerosol is reduced due to transfer of thermal energy to the aerosol-cooling element 940. Furthermore, water droplets condense out of the aerosol and adsorb to internal surfaces of the axial channels defined through the aerosol-cooling element 940.

[0140] When the aerosol enters the aerosol-cooling element 940, its temperature is about 60 degrees Celsius. Due to cooling within the aerosol-cooling element 940, the temperature of the aerosol as it exits the aerosol cooling element 940 is about 40 degrees Celsius. Furthermore, the water content of the aerosol is reduced. Depending on the type of material forming the aerosol-cooling element 940, the water content of the aerosol may be reduced from anywhere between 0 and 90 percent. For example, when element 940 is comprised of polylatic acid, the water content is not considerably reduced, that is, the reduction will be approximately 0 percent. In contrast, when the starch based material, is used to form element 940, the reduction may be approximately 40 percent. It will now be apparent to one of ordinary skill in the art that through selection of the material comprising element 940, the water content in the aerosol may be adapted.