Apparatus and method for the production of sheet like tobacco material

Abstract

The invention relates to a method or apparatus (10) for crimping a sheet (70) of material The apparatus comprises a transport device to transport the sheet of material along a transport direction (1), and a set of crimping rollers (11, 21). The set comprises a first (11) and a second (21) main crimping roller, defining a first (18) and a second (28) rotational axis and being faced one in front of the other, the first roller including a first plurality of ridges (17) across a portion of its width (16), and the second roller having a second plurality of ridges (27) across a portion of its width; and a pre-crimping roller facing the first roller and having a third plurality of ridges across a portion of its width, the pre-crimping roller having a diameter smaller than a diameter of the first and second main roller.

Claims

1. A method of manufacturing a crimped sheet of material for an aerosol-generating article, the method comprising the steps of: feeding a substantially continuous sheet of material to a set of crimping rollers in a transport direction, the set of rollers comprising a first main roller, a second main roller and a pre-crimping roller, the first and second main rollers including a first and a second plurality of ridges, respectively, across at least a portion of their width and the pre-crimping roller including a third plurality of ridges across a portion of its width, the pre-crimping roller being of a smaller diameter than the first and second main rollers wherein the first plurality of ridges has a first given pattern, the second plurality of ridges has a second given pattern, and the third plurality of ridges has a third given pattern, the third pattern being different from the first pattern of the first plurality of ridges; pre-crimping the substantially continuous sheet of material to form a pre-crimped sheet by feeding the substantially continuous sheet between the first main roller and the pre-crimping roller such that the first plurality of ridges of the first main roller and the third plurality of ridges of the pre-crimping roller apply a first pattern of crimp corrugations to the substantially continuous sheet; and crimping the pre-crimped sheet of material to form a crimped sheet by feeding the substantially continuous sheet between the first main roller and the second main roller such that the first and second plurality of ridges of the first and second main rollers apply a second pattern of crimp corrugations to the pre-crimped sheet.

2. The method according to claim 1, wherein the pre-crimping roller is idle.

3. The method according to claim 1, wherein the pre-crimping roller is located upstream the first and second main rollers in the direction of transport of the sheet of material.

4. The method according to claim 1, wherein the ridges of the first plurality defines a first ridge amplitude and the ridges of the third plurality defines a third ridge amplitude, and wherein the third amplitude is shorter than the first amplitude.

5. The method according to claim 1, wherein a number of ridges per unit length along a direction parallel to the axis of rotation of the roller in the first plurality is higher than the number of ridges per unit length along a direction parallel to the axis of rotation of the roller in the third plurality.

6. The method according to claim 1, wherein the set of crimping rollers includes a second pre-crimping roller facing the first main roller, the second pre-crimping roller being positioned upstream the pre-crimping roller in the transport direction.

7. The method apparatus according to claim 6, wherein the second pre-crimping roller includes a fourth plurality of ridges having a fourth pattern.

8. The method according to claim 1, wherein the set of crimping rollers includes a plurality of pre-crimping rollers, each pre-crimping roller facing the first main roller, and the plurality of pre-crimping rollers being placed adjacent the first main roller within an angular interval centered at a rotational axis of the first main roller of less than about 180°.

9. The method according to claim 1, wherein the set of crimping rollers includes a second pre-crimping roller, a diameter of the second pre-crimping roller being smaller than the diameter of the first and second main rollers.

10. The method according to claim 1, wherein the diameter of the first main roller is substantially equal to the diameter of the second main roller.

11. The method according to claim 1, wherein the sheet of material is one of: a homogenized tobacco sheet, a plastic sheet or a sheet including cellulose.

12. The method according to claim 1, including the steps of: gathering the crimped sheet of material, and forming a rod using the gathered crimped sheet of material.

13. The method according to claim 12, including: wrapping the rod.

14. The method according to claim 13, comprising the step of: 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.

Description

(1) The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows an isometric view of an apparatus having two main rollers and a pre-crimping roller between which a sheet of material is treated according to the invention;

(3) FIG. 2 shows a two-dimensional representation of a surface of a roller having a ridge-and-trough pattern;

(4) FIG. 3 shows in a side view an arrangement of two main rollers and a set of pre-crimping rollers between which a sheet of material is transported;

(5) FIG. 4 shows a schematic top view of a treated sheet according to the invention where gathering and forming a rod and sticks is indicated;

(6) FIG. 5 shows a flow chart of a method for crimping a sheet of material according to the invention.

(7) With initial reference to FIG. 1, the Figure shows an isometric view of an apparatus 10 comprising a first and second facing main crimping rollers 11, 21 between which a sheet 70 of material having the width 76 is treated according to the invention. The transport direction 1 of the sheet 70 is indicated with an arrow 1 in the FIG. 1.

(8) The first and second facing crimping roller 11, 21 define a first and second rotation axis 18, 28, respectively. The surfaces of the rollers 11, 21 are provided with corrugations, where ridge- and trough pattern or corrugations 17, 27 are typically circumferential ridges on the surface of each roller 11, 21. The circumferential ridges may be perpendicular with respect to the rotation axes 18, 28 or may be slightly inclined.

(9) The diameter of the first and second crimping roller is of about 208 millimeters.

(10) The corrugations 17, 27 (not shown in detail in the figure) of the first and second rollers 11, 21 at least partially mesh. The corrugations 17, 27 of one or both of the rollers 11, 21 are symmetrical or asymmetrical. The peak of one or more corrugations of the first or second rollers 11, 21 may interleave with the trough of a single corrugation of the other of the first and second rollers 11, 21. Preferably, the corrugations 17, 27 of the first and second rollers 11, 21 interleave such that substantially all of the corrugation troughs of one of the first and second rollers 11, 21 each receive a single corrugation peak of the other of the first and second rollers 11, 21. The surface patterns of both rollers 11, 21 are transmitted to the surfaces of the sheet 70 when transported between the two rollers 11, 21.

(11) The amplitude of the corrugations in the first and second roller is equal to about 0.67 millimeters.

(12) The apparatus 10 also comprises a pre-crimping roller 31, which defines a rotation axis 38 parallel to the rotation axes 18, 28 of the main rollers 11, 21, and which at least partially meshes with the first main roller 11. The pre-crimping roller 31 rolls on the first main crimper 11 prior to crimping. No motor or pulley drives the pre-crimping roller, the motion of the main roller or the friction with the sheet put it into motion.

(13) The pre-crimping roller 31 includes corrugations having an amplitude of 0.67 millimeters. Preferably, the distance between the pre-crimper and the first crimping roller is bigger than the distance between the first and second rollers, so the ridges of the pre-crimping roller do not go as deep in the sheet as those of the first and second roller when the sheet is in the crimping phase.

(14) For example, the distance between the main first and second rollers is such that the corrugations formed in the sheet of material have a depth preferably comprised between about 0.36 millimeters and about 0.4 millimeters. For example, the distance between the main first and pre-crimping rollers is such that the corrugations formed in the sheet of material have a depth preferably comprised between about 0.25 millimeters and about 0.35 millimeters.

(15) The sheet 70 runs on the first main roller 11 and is then transported between the pre-crimping roller 31 and the first main roller 11 and subsequently transported between the two main rollers 11, 21.

(16) Accordingly, the sheet 70 moves between this pre-crimping roller 31 and the first main roller 11 to be pre-crimped prior to the main crimping process which takes place between the two main rollers 11, 21. Advantageously, the number of ridges of the pattern of the pre-crimping roller 31 may differ from the number of ridges of the pattern of the main crimping rollers 11, 21 and/or the depth of the troughs and/or the amplitude of ridges may be different. This results in a gently pre-crimping of the sheet 70 before the main crimping process is performed between the two main rollers 11, 21, thus allowing a higher processing speed without damaging the sheet 70.

(17) As can be seen in FIG. 2, where the first roller 11 is depicted as a two dimensional area for clarity, the surface 12 of the roller 11 has a conventional ridge-and-trough pattern 17. The ridge-and-trough pattern 17 is comprised of circumferential ridges, each ridge defining a ridge amplitude. The ridges can be oriented perpendicular to the rotation axis 18 or can be slightly inclined, e.g. by not more than 10°.

(18) The crimping is characterized among others by the number of lines of the corrugation pattern of the main crimping rollers 11, 21 and the depth of the troughs and the amplitude of the ridges of the corrugations 17, 27.

(19) The second main roller 21 (FIG. 1) preferably has the same size and the same ridge- and trough pattern 27 (FIG. 1) as corrugations as the first main roller 11.

(20) FIG. 3 shows in a side view a detail of a schematically depicted further embodiment of an apparatus 99 for crimping the sheet 70. Detail analog to apparatus 10 are indicated with the same reference number. The apparatus 99 comprises an arrangement of two main rollers 11, 21 and a set of pre-crimping rollers 31, 41, 51, 61 between which a sheet 70 of material is transported. The pre-crimping rollers 31, 41, 51, 61 are rolling on the first main roller 11 so that the sheet 70 of material is transported successively between the pre-crimping rollers 31, 41, 51, 61 and the first main roller 11.

(21) Each pre-crimping roller 31, 41, 51, 61 has a specific crimping pattern determined according to the crimping pattern (corrugations 17) of the main roller 11 and according to the patterns of the other pre-crimping rollers 31, 41, 51, 61. As a result, the cumulative and successive action of the pre-crimping rollers 31, 41, 51, 61 on the sheet 70 create a progressive crimping action on the sheet 70, for gently preparing the sheet 70 for the crimping, decreasing the crimping damage.

(22) Optionally, each pre-crimping roller 31, 41, 51, 61 has only a part of the total crimping corrugations 17, 27 of the crimp pattern of the main roller 11, e.g. each pre-crimping roller 31, 41, 51, 61 having a pitch value which is larger than the pitch value of the main roller. For instance, in case of four pre-crimping rollers 31, 41, 51, 61, each pre-crimping roller 31, 41, 51, 61 may have only one crimping ridge in a unit length where the main roller 11 has four crimping ridges, so that the sum-up pattern of the four pre-crimping rollers 31, 41, 51, 61 is similar to the crimp corrugation of the main crimper 11. The crimping deformation on the sheet 70 material during the pre-crimping phase is only of ¼th on each pre-crimping roller 31, 41, 51, 61.

(23) Optionally, each pre-crimping roller 31, 41, 51, 61 may have only one crimping ridge in a unit length where the main roller 11 has five crimping ridges (or above), so that the sum-up pattern of the four pre-crimping rollers 31, 41, 51, 61 is inferior to the pattern of the main crimper 11. The pitch value can be the same for each pre-crimping roller 31, 41, 51, 61. Optionally, the pitch value can be different among the pre-crimping rollers 31, 41, 51, 61. For instance, the first pre-crimping roller 31 that encounters the incoming sheet 70 may have only one crimping ridge in a unit length where the main roller has four or more crimping ridges, the second pre-crimping roller 41 may have two crimping ridges in the unit length etc. up to the same number of crimping ridges in the unit length as the main roller 11.

(24) Optionally, each pre-crimping roller 31, 41, 51, 61 may have the same number of crimping ridges as the main roller 11, but the depth of the crimping increases from one pre-crimping roller 31, 41, 51, 61 to the next. In such embodiments, the troughs in the sheet 70 of material are progressively extended up to a depth slightly inferior to the crimping depth caused by the main rollers 11, 21. For instance in case of four pre-crimping rollers 31, 41, 51, 61, the first pre-crimping roller 31 that encounters the incoming sheet 70 may have a smooth or slightly textured surface, the second pre-crimping roller 41 may have a ridge amplitude of only 25% of the ridge amplitude of the main roller 11, the third pre-crimping roller 51 of 50% and the fourth pre-crimping roller 61 of 75% of the ridge amplitude of the main roller 11.

(25) Optionally, each pre-crimping roller 31, 41, 51, 61 may have the same number of ridges per unit length as the main roller 11 with the same ridge amplitude, but a distance between the pre-crimping rollers 31, 41, 51, 61 and the main roller 11 decreases progressively. For instance, the distance between the main roller and the pre-crimping rollers 31, 41, 51, 61 may be reduced from the first pre-crimping roller 31 up to the last one for which the distance is slightly higher than the final distance between the two main rollers 11, 31.

(26) In a preferred embodiment, the diameter of the pre-crimping rollers 31, 41, 51, 61 is about 1/10th of the diameter of the main roller 11. For instance the diameter of the pre-crimping rollers 31, 41, 51, 61 may be selected between about 0.015 m and about 0.03 m (up to 0.05 m) when the main roller 11 has a diameter of 0.20 m. This allows to arrange the pre-crimping rollers 31, 41, 51, 61 in less than 180° of the main roller 11.

(27) Optionally, the progressive crimping action of the pre-crimping rollers 31, 41, 51, 61 may be performed in the following ways:

(28) In case the crimping corrugation is not only made of corrugations parallel to the direction of the sheet 70, the corrugation pattern of each pre-crimping roller 31, 41, 51, 61 and the corrugation pattern of the main roller 11 the respective pre-crimping roller 31, 41, 51, 61 is rolling on must be so that the corrugation pattern on the surface of the one main roller 11 is N times the corrugation pattern on the pre-crimping roller 31, 41, 51, 61 surface, N being the number of times the peripheral of the pre-crimping roller 31, 41, 51, 61 could be put into the peripheral surface of the main roller 11. N is also equal to the ratio of the diameter of the main roller 11 divided by the diameter of the pre-crimping roller 31, 41, 51, 61.

(29) FIG. 4 shows a schematic top view of a crimped sheet 70 according to the invention where gathering and forming a rod 80 and sticks 82 is indicated.

(30) The surface of the sheet 70 shows corrugations which reproduce the corrugations on the surface of roller 11 in FIG. 2, for instance. The crimped sheet 70 of material is gathered and formed into a rod 80. The crimp corrugations of the crimped sheet 70 define a plurality of channels in the rod 80. The rod 80 is then wrapped and cut into sticks 82 having a stick length 84.

(31) FIG. 5 shows a flow chart of a method for crimping a sheet of material according to the invention.

(32) In a first step 100 a substantially continuous sheet of material is fed to a set of crimping rollers in a transport direction. The set of rollers comprise a first main roller, a second main roller and a pre-crimping roller. The first and second main rollers include a first and a second plurality of ridges across at least a portion of its width and the pre-crimping roller includes a third plurality of ridges across a portion of its width, a diameter of the pre-crimping roller being smaller than a diameter of the first and second main rollers.

(33) In step 102, the substantially continuous sheet of material is pre-crimped between the first main roller and the pre-crimping roller to form the pre-crimped sheet by feeding the substantially continuous sheet between the first main roller and the at least one pre-crimping roller in the transport direction of the sheet such that the first plurality of ridges of the first main roller and the third plurality of ridges of the pre-crimping roller apply a first pattern of crimp corrugations to the substantially continuous sheet.

(34) In step 104 the substantially continuous and pre-crimped sheet of material is crimped to form a crimped sheet by feeding the substantially continuous sheet between the first main roller and the second main roller such that the first and second plurality of ridges of the first and second main rollers apply a second pattern of crimp corrugations to the pre-crimped sheet.

(35) In step 106, the crimped sheet of material is gathered, and a continuous rod is formed using the crimped sheet of material in step 108. In step 110, the continuous rod is wrapped, e.g. in cigarette paper.

(36) In step 112, the continuous wrapped rod is cut into a plurality of rod-shaped components (sticks), 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.