Apparatus and method for the production of sheet like tobacco material

Abstract

The invention relates to an apparatus (10) for crimping a sheet (40) of material, the apparatus comprising a first and second facing crimping roller (11, 21) defining a first and second rotation axis, respectively, the first roller including: •a first plurality of circumferential ridges (16), each ridge defining a ridge amplitude; •wherein each of said first plurality of ridges is interrupted along its circumferential extension forming an interruption gap where for a given interruption angle an amplitude of the ridge differs from the ridge amplitude in the remaining circumferential extension of the ridge; •wherein said plurality of interruption gaps forms an interruption band defining a direction of extension, said direction of extension being angled with respect to a direction defined by the first rotation axis of an angle comprised between about 2° to about 25°. The invention also relates to a method for crimping a sheet of material as well as a crimped sheet of material and a rod made of a crimped sheet.

Claims

1. A method for crimping a sheet of material, the method comprising: feeding a substantially continuous sheet of material to a set of crimping rollers in a transport direction, the set of rollers comprising a first roller and a second roller, at least one of the first or second roller including a first non-uniform plurality of ridges across at least a portion of its width; crimping the substantially continuous sheet of material to form the crimped sheet by feeding the substantially continuous sheet between the first and second rollers in the transport direction of the sheet such that the corrugations of the first or second rollers apply a plurality of crimp corrugations to the substantially continuous sheet, the crimp corrugations having a first crimp pattern for a first portion and a second pattern for a second portion; the crimp corrugations forming a plurality of bands onto the crimped sheet, each band alternatively including the first or the second crimp pattern, the bands defining a direction of extension, and said direction of extension forms an angle comprised between about 2° to about 25° with an axis perpendicular to the transport direction.

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

3. The method according to claim 2, including: 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 rollers 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 crossed by interruption bands;

(4) FIG. 3 shows a sheet of material after treatment in the apparatus of FIG. 1 according to the invention;

(5) FIG. 4 shows a schematic top view of a treated sheet having areas without a differently crimped band according to the invention;

(6) FIG. 5 shows a schematic top view of a treated sheet having areas with overlapping differently crimped bands according to the invention;

(7) FIG. 6 shows a schematic top view of a treated sheet of material with optimized arrangement of differently crimped bands according to the invention; and

(8) FIG. 7 shows a flow chart of a method for crimping a sheet of material according to the invention.

(9) With initial reference to FIG. 1, the Figure shows an isometric view of an apparatus 10 comprising a first and second facing crimping rollers 11, 21 between which a sheet 40 of material having a width 46 is treated according to the invention. The transport direction 1 of the sheet 40 is indicated with an arrow pointing to left forward in the figure.

(10) The first and second facing crimping roller 11, 21 define a first and second rotation axis 17, 27, respectively. The surfaces of the rollers 11, 21 are provided with corrugations, where ridge- and trough pattern 16, 26 are indicated by two circumferential lines on the surface of each roller 11, 21.

(11) One or both rollers 11, 21 have uncrimped and/or less corrugated areas and are mutually arranged so that such areas on one roller 11 or 21 is facing other such areas or usual ridge- and trough pattern 16, 26 on the other roller 21 or 11 during the crimping process.

(12) The corrugations of the first and second rollers 11, 21 at least partially mesh. The corrugations of one or both of the rollers 11, 21 are symmetrical or asymmetrical. The corrugations of the rollers 11, 21 may be substantially aligned, or at least partially offset. 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 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 40 when pressed between the two rollers 11, 21.

(13) 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 16 combined with parallel bands 13, also called interruption bands in the following, having a different pattern, in this example a smooth surface 18. The ridge-and-trough pattern 16 is comprised of circumferential ridges, each ridge defining a ridge amplitude. The ridges can be oriented perpendicular to the rotation axis 17 or can be slightly inclined, for example by not more than about 10°. The ridges are crossed by interruption bands 13.

(14) Generally, the interruption band 13 is corrugated differently than the ridge-and-trough pattern 16. The interruption band 13 may comprise a less corrugated pattern than the ridge-and-trough pattern 16 with a lower ridge amplitude or a smaller number of ridges and troughs, for example a larger pitch value (denoted as “less crimped”). The interruption band 13 may be a concave band where no pressing of the sheet 40 occurs or may have a smooth surface 18 where no corrugation is created by the crimping process (denoted as “uncrimped”).

(15) The roller 11 can have combinations of a conventional ridge-and-trough pattern 16 and interruption bands 13 which are less corrugated or uncorrugated. Dimensions and geometries can vary on the same roller 11. Both rollers 11 and 21 can be provided with such interruption bands 13.

(16) The other roller 21 as shown in FIG. 1 may have a conventional crimping surface.

(17) The interruption band 13 is formed by a first plurality of circumferential ridges where each ridge is interrupted by an interruption gap and where for a given interruption angle an amplitude of the ridge differs from the ridge amplitude in the remaining circumferential extension of the ridge. The interruption band 13 is inclined with respect to an axis parallel to the first rotation axis 17 by an angle α. The angle α is different from about 0° and from about 90° and it is comprised between about 2° and 25°. In FIG. 2, the angle α is the angle between the band and an axis—still indicated with 17—parallel to the first rotational axis.

(18) The interruption bands 13 are arranged parallel to each other and spaced apart by a constant distance 15. Further, a is constant in the whole band.

(19) Preferably, the distance 15 between two interruption bands 13 is less than a length of a rod (FIG. 3). The distance 15 is calculated as the distance along an axis perpendicular to the longitudinal axis 17 of the roller 11 from the end of an interruption band 13 to the start of the next interruption band 13. Preferably, the distance 15 between two bands 13 is constant.

(20) FIG. 3 shows a sheet 40 of material after treatment in the apparatus 1 of FIG. 1 according to the invention. The surface of the sheet 40 shows corrugations which substantially reproduce the corrugations on the surface of roller 11 in FIG. 2, for instance. The interruption bands 13 (FIG. 1) are reproduced as bands 43 on the sheet 40 which are crimped differently as compared to the corrugations 42 which reproduce the ridge-and-trough pattern 16 of the rollers in FIG. 2 outside the interruption bands 13.

(21) The differently crimped bands 43 are, in this example, provided with smooth surfaces. The differently crimped bands 43 are inclined with respect to the direction of the sheet 40 perpendicular to the longitudinal extension by an angle α which is the same angle as the inclination angle α of the interruption bands 13 with respect to the longitudinal axis 17 in the roller in FIG. 2. Angle α is thus the angle between the band and a direction perpendicular to the transport direction indicated with 1 in FIG. 1.

(22) The crimped sheet 40 of material is gathered and formed into a rod shaped component 50. The crimp corrugations of the crimped sheet 40 define a plurality of channels in the rod-shaped component 50. The rod shaped component 50 is then cut into rods 52 having a rod length 54 which is preferably equal to the distance 15 between two differently crimped bands 43.

(23) By way of example, the crimper rollers 11, 21 are about 0.32 meters long with a diameter of 0.21 meters. the width 46 of the sheet is about 0.125 meters±0.05 meters. The angle α is about 13° 20′±10°. The width of the uncrimped areas 43 in the sheet 40 is about 0.0028 meters±0.002 meters which is about 20-25% of the rod length. The distance between two uncrimped areas 43 is equal to the rod length 54, while the rod length 54 is about 0.012 meters±0.005 meters.

(24) With such values, tests on a tobacco cast leaves material have shown a sharp decrease in the fly-out effect as well as a higher tensile strength as compared to conventionally crimped material. The resistance of the improved sheet 40 against fly-out can be increased by about 50%. This was found in a fly-out test set-up which was done by fixing several rods radially on a motorized disc that will accelerate up to about 650 turns per second. These rods, usually part of aerosol generating articles, include a tobacco rod at their distal part. Outside the peripheral of the disc, untouched by the rods at start, a laser detector is emitting a laser beam perpendicular to the surface of the disc. This laser detector sends a signal as soon as its beam is blocked by a part of the tobacco rod pushed away from the fixed rods by the centrifugal force of the rotation of the motorized disc. The moment this signal is emitted indicate the end of the test and give a value of the resistance of the tobacco rod to “fly out” effect.

(25) Referring now to FIGS. 4-6, which depict schematic top views of crimped sheets 40, the figs. show the influence of comprising different distances of the uncrimped or less crimped bands 43 in the sheets 40.

(26) As can be seen in FIG. 4, when the distance 45 between two uncrimped bands 43 is more than the rod length 54, areas 44 are created in the rod without an uncrimped band where “fly out” effect may occur.

(27) FIG. 5 shows that when the distance 45 between two uncrimped bands 43 is smaller than the rod length 54, there are areas 47 where there is, along the longitudinal axis of the rod, more than one uncrimped band 43. When the sheet 40 is compressed into a rod, this can create an unfavourable distribution of the sheet 40 that could reduce the resistance to draw below a desired level.

(28) FIG. 6 shows a preferred arrangement where the uncrimped bands 43 in the sheet 40 are such that the distance 45 between the uncrimped bands 43 is equal to the rod length 54, which favourably prevents the problems indicated in FIGS. 4 and 5.

(29) FIG. 7 shows a flow chart of a method for crimping a sheet of material according to the invention.

(30) 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 roller and a second roller, where at least one of the first or second roller includes a first non-uniform plurality of ridges across at least a portion of its width.

(31) In step 102, the substantially continuous sheet of material is crimped to form the crimped sheet by feeding the substantially continuous sheet between the first and second rollers in the transport direction of the sheet such that the corrugations of the first or second rollers apply a plurality crimp corrugations to the substantially continuous sheet. The first or the second portion includes bands extending from one lateral side to the other of the crimped sheet.

(32) In step 104 a plurality of parallel crimped bands are formed onto the crimped sheet, each band alternatively including a first or the second crimp pattern. Preferably, the second crimp pattern is a smooth pattern.

(33) In step 106, the crimped sheet of material is gathered and a rod is formed using the crimped sheet of material in step 108.

(34) In step 108 the continuous rod is cut 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.

(35) Finally, in step 110 the continuous rod is cut in a plurality of rod shaped articles having a length substantially equal to a distance between two parallel differently crimped bands.