Crimping Roller with Increased Number of Interruption Gaps

The present invention relates to a method for producing a plug forming part of an aerosol-generating article, a plug for forming part of an aerosol-generating article, a crimping roller and a use of interrupted circumferential ridges on a crimping roller to form a plurality of interrupted crimp corrugations on a sheet prior to forming a plug out of the sheet.

WO2018189325A1 discloses a crimping roller having corrugations with inclined interruption bands. EP3214959B1 discloses a method and apparatus for manufacturing a crimping web.

There is a need for improving the strength, in particular the tensile strength, of crimped sheet material. There is also a need for preventing the release of substances, in particular loose particles of aerosol-generating substrates, out of a crimped and gathered sheet. There is also a need for controlling the resistance-to-draw value of a crimped sheet material.

According to a first aspect of the invention, there is provided a method for producing a plug forming part of an aerosol-generating article. A sheet is fed along a longitudinal direction of the sheet to a set of crimping rollers. The sheet is crimped to form a crimped sheet. The crimped sheet comprises a plurality of corrugated regions and a plurality of interruption bands. In the corrugated regions, the crimped sheet comprises a plurality of corrugations extending in the longitudinal direction. In the interruptions bands, the crimped sheet is free of corrugations or comprises corrugations having a smaller corrugation amplitude compared to the corrugations in the corrugations regions. The interruption bands and the corrugated regions are alternatingly arranged. Each interruption band of the plurality of interruption bands comprises a leading portion and a trailing portion. The leading portion is arranged at a different location with respect to the longitudinal direction than the trailing portion. The leading portion and the trailing portion may be arranged at opposite sides of the crimped sheet with respect to the width of the sheet. The crimped sheet is gathered to form a gathered sheet. A plug is formed out of the gathered sheet. In the crimped sheet, the distance between two adjacent interruption bands in the longitudinal direction is smaller than half of the length of the plug in the longitudinal direction.

The plug may extend predominantly in the longitudinal direction.

A crimped sheet may be formed, on which surface patterns having a specific distribution of corrugated regions and non-corrugated or less corrugated regions may be created to form a crimping pattern. The crimping pattern may allow to maintain good overall tensile strength of the sheet and may prevent fly outs.

The plurality of corrugations in the corrugated regions may extend in a direction that is inclined to the longitudinal direction.

The term sheet may refer to a laminar element having a width and length substantially greater than its thickness. The term corrugations may refer to a plurality of substantially parallel ridges. The corrugations may have a square wave profile, a sinusoidal wave profile, a triangular profile, a saw-tooth profile, or a combination thereof. The term crimped sheet may refer to a sheet having a plurality of corrugations. The term gathered may denote that a sheet is convoluted or otherwise compressed or constricted substantially transversely to the longitudinal direction.

Crimping may be different from embossing. Embossing may refer to forming indentations on a surface of an element by pressing an external object against the surface of the element to form the indentation. In crimping, a sheet material may be pushed against ridges or ridges may be pushed against a sheet material. The ridges may apply pressure to the sheet material, such that the sheet material may bend over the ridges. This may cause the sheet material to break open on the opposite side of the respective ridge.

The corrugation amplitude may refer to the height of the corrugation, in particular the distance the corrugation protrudes from the rest of the sheet. The corrugation amplitude may refer to the distance between the peak of the corrugation to the base of the corrugation.

The distance between two adjacent interruption bands may be defined as the distance from an edge of a first interruption band to an edge of a second interruption band, in particular adjacent to the first interruption.

The corrugated regions may define channels in the plug. The channels may extend in the longitudinal direction. The interruption bands may prevent fly out of loose pieces of aerosol-generating substrate from the channels during the making of the plug or transport. Having interruption bands with a distance between two adjacent interruption bands smaller than half of the plug length may prevent fly out of pieces of the aerosol-generating substrate on both ends of the plug. Having interruption bands with a distance between two adjacent interruption bands smaller than half of the plug length may improve the shape of the plug and may result in a more even surface of the plug. The crimped material may be gathered easier and more evenly. It may also increase the strength, in particular the tensile strength, of the crimped material. It may improve the formation of air passages or air channels in the plug. It may result in a better resistance-to-draw value of the plug. It may provide a balance between improved channel formation in the crimped sheet and the plug as well as improved tensile strength of the crimped sheet and the plug.

A continuously crimped sheet, without any interruption bands, may have a relatively low tensile strength because the crimp corrugations weaken the sheet material. This may cause problems when the crimped sheet is transported from the crimping rollers to the wrapping or gathering tool. In the region of the interruption bands the sheet may be not crimped or less crimped, thus the material is less weakened, leading to a higher tensile strength compared to the crimped regions. However, the thickness of the sheet material in the regions of the interruption bands may be greater due to being not or less crimped. This may cause problems when the crimped sheet is gathered. For example, when the crimped sheet is gathered, the uncrimped or less crimped regions may obstruct the parallel alignment of the channels that are formed in the crimped material and may add randomness to the alignment of the channels. Such randomness may result in unpredictability of the fluid dynamics in the plug and thus undesired resistance-to-draw values. It may also complicate the insertion of a heating element into the plug. Spacing the interruption bands closer together may create a more even distribution between interruption bands and crimped regions. Thus, the tensile strength of the crimped sheet may be increased as well as less randomness in the alignment of channels may be caused when the crimped sheet is gathered. This may lead to a better resistance-to-draw value of the finished plug.

Having interruption bands comprising a leading portion and a trailing portion, wherein the leading portion may be arranged at a different location with respect to the longitudinal direction than the trailing portion may result in inclined interruption bands. Inclined interruption bands may improve the shape of the plug and may result in a more even surface of the plug. The interruption bands may be inclined with respect to the longitudinal direction. The interruption bands may be inclined with respect to a direction orthogonal to the longitudinal direction.

The leading portion and the trailing portion may be arranged adjacent to opposite edges of the crimped sheet with respect to the width of the crimped sheet. The leading portion may be arranged at a first side of the crimped sheet. The trailing portion may be arranged at a second side of the crimped sheet. The first side may be arranged on one end of the extension of the crimped sheet orthogonal to the longitudinal direction. The first side may be arranged on the other end of the extension of the crimped sheet orthogonal to the longitudinal direction.

Each interruption band may extend primarily along a main path, referred to as primary extension of the interruption band. A secondary extension of the interruption band may be the extension of the interruption band in the longitudinal direction. The direction of the primary extension may be different from the direction of the secondary extension. The corresponding main paths of adjacent interruption bands may be parallel to each other. The corresponding main paths of adjacent interruption bands may be offset by a distance in the longitudinal direction.

Each main path, also referred to as the main path, may start at a path start point adjacent to a first side. The main path may end at a path end point adjacent to a second side. The first side and the second side may be arranged on opposite sides with respect to the width of the crimped sheet. The direction of the main path may change along its extension from the path start point to the path end point. The main path may have a chevron shape. The main path may have a triangle shape. All main paths may be parallel to each other. All main paths may extend predominantly in the same direction.

The longitudinal distance between two adjacent interruption bands may be smaller than one third of the length of the plug in the longitudinal direction. The longitudinal distance between two adjacent interruption bands may be smaller than one fourth or one fifth of the length of the plug in the longitudinal direction. Reducing the longitudinal distance between adjacent interruption bands may result in a better protection against fly out of the aerosol-generating substrate, may result in a more even surface of the plug and may increase the strength, in particular the tensile strength, of the crimped material. It may also result in a better resistance-to-draw value of the plug. The crimped sheet may also be gathered easier and more evenly.

At least three, at least four, or at least five interruption bands may be formed in the sheet over a longitudinal distance equal to the length of the plug in the longitudinal direction.

The step of forming a plug from the gathered sheet may comprise the steps of forming a rod out of the gathered sheet and cutting the rod to form the plug. It may be more efficient to form a long rod first, and to subsequently cut the rod into multiple plugs. This may increase throughput.

Cutting the rod to form a plug may comprise two to five, preferably three to four cutting steps. The rod may be cut into two to sixteen, preferably four to eight plugs. The rod may be cut into a plurality of substantially uniform plugs. Forming multiple plugs out of one rod may increase production efficiency.

The plug may be a filter for an aerosol-generating article. The plug may be used to form or to contain an aerosol-generating substrate.

The crimped sheet may be cut into a predefined length prior to gathering the crimped sheet to form a gathered sheet. The corrugations may be formed on a continuous sheet to form a continuous crimped sheet. The continuous crimped sheet may be cut into a predefined length prior to gathering the sheet. Cutting the sheet into a predefined length may facilitate gathering the sheet.

The plurality of interruption bands may be uniformly spaced from each other. This may result in a better protection against fly out of the aerosol-generating substrate, may result in a more even surface of the rod and may increase the strength, in particular the tensile strength, of the crimped material. It may also result in a better resistance-to-draw value of the rod. The crimped sheet may also be gathered easier and more evenly.

An angle between the extension of the interruption bands in the crimped sheet and the longitudinal direction may be between 70 degrees and 90 degrees, in particular between 75 and 85 degrees, in particular about 84 degrees.

The interruption bands may be inclined with respect to the longitudinal direction. The inclination of an interruption band may vary along the extension of the interruption band. An interruption band may be inclined in two opposite directions with respect to the longitudinal direction. The sign of the value of the inclination of an interruption band may change along the extension of the interruption band. For example, the interruption bands may have a chevron shape, a diamond shape or a triangular shape. This means that the width of the interruption bands may change along the extension of the interruption bands. The interruption bands may be curved. The interruption bands may have the shape of a wave. The sign of the value of the inclination of an interruption band may change multiple times along the extension of the interruption band.

The leading portion of the interruption band may be in front of the trailing portion of the interruption band with respect to the longitudinal direction. The interruption band may comprise two or more leading portions. The interruption band may comprise two or more trailing portions.

The interruption bands may extend at an angle of more than 60 degrees with respect to the longitudinal direction. At least three interruption bands may intersect a straight line across the sheet orthogonal to the longitudinal direction.

The interruption bands may be parallel to each other. The channels formed by the corrugations in the crimped sheet may have substantially the same length.

The extension of an interruption band in the longitudinal direction may be between 2 millimeters and 5 millimeters, in particular between 3 millimeters and 4 millimeters, in particular about 3.5 millimeters. Such a value may be sufficient to interrupt the channels inside the crimped sheet. Such a value may be optimal to improve the resistance to draw value of theplug. Such a value may be optimal to improve the shape of the plug.

An interruption band width may be the extension of an interruption band in the longitudinal direction. The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 5, in particular between 1 and 3, in particular about 2. Such a value may be sufficient to interrupt the channels inside the crimped sheet. Such a value may be optimal to improve the resistance to draw value of the plug. Such a value may be optimal to improve the shape of the plug. The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 2, between 1 and 3, between 2 and 4 or between 3 and 5. The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 1, between 1 and 2, between 2 and 3, between 3 and 4 or between 4 and 5.

The interruption band width may be constant within an interruption band. All interruption bands may have the same interruption band width. The interruption band width may vary within an interruption band. The interruption band width may vary between different interruption bands. All interruption bands may have the same shape.

The distance between two adjacent interruption bands in the longitudinal direction may be greater than the extension of an interruption band in the longitudinal direction.

The distance between two adjacent interruption bands in the longitudinal direction may be smaller than 6 millimeters. The distance between two adjacent interruption bands in the longitudinal direction may be smaller than 6 millimeters and smaller than half of the length of the plug in the longitudinal direction.

A crimped sheet width may be the extension of the crimped sheet orthogonal to the longitudinal direction. The interruption band may be discontinuous across the crimped sheet width. The interruption bands may be interrupted by interruption band gaps. Interruption band gaps of two adjacent interruption bands may be arranged at an offset with respect to a direction orthogonal to the longitudinal direction. This may ensure that interrupted channels are formed in the crimped sheet. The plurality of interruption bands may be discontinuous across the crimped sheet width.

The length of the plug in the longitudinal direction may be between 5 millimeters and 20 millimeters, in particular between 7 millimeters and 17 millimeters, in particular about 12 millimeters. A plug with such a length may be used in a cigarette. A plug with such a length may be used in an aerosol-generating article for an electronic smoking device.

A sheet width may be the extension of the sheet in a direction orthogonal to the longitudinal direction. The sheet width may be 5 centimeters to 20 centimeters, in particular about 11 centimeters. Such a sheet width may result in a plug of a desired diameter, in particular to be used in an aerosol-generating article.

According to a second aspect of the invention, there is provided a plug for forming part of an aerosol-generating article. The plug may be formed with the method according to the first aspect of the invention. The plug extends in a longitudinal direction. The plug comprises a gathered sheet. The gathered sheet may comprise a plurality of corrugation lines extending in the longitudinal direction. At least one corrugation line of the plurality of corrugation lines is interrupted at least three times in the longitudinal direction by interruption bands.

Such a configuration of interrupted corrugation lines may result in a better protection against fly out of an aerosol-generating substrate in the plug, may result in a more even surface of the plug and may increase the strength, in particular the tensile strength, of the plug. It may also result in a better resistance-to-draw value of the plug. The sheet may also be gathered easier and more evenly.

At least one corrugation line of the plurality of corrugations lines may be interrupted at least four times in the longitudinal direction by interruption bands.

All corrugations lines of the plurality of corrugations lines may be interrupted at least twice or at least three times in the longitudinal direction by interruption bands.

The interruption bands may be flat sections or sections with corrugations having a smaller corrugation amplitude compared to the rest of the corrugation line.

A corrugation line may be a substantially straight corrugation or ridge. An interruption band may be a region where the corrugation line has a lower corrugation amplitude compared to the rest of the corrugation line. An interruption band may be a non-corrugated region.

The interruption bands may be inclined with respect to the longitudinal direction. An angle between the extension of the interruption bands in the gathered sheet and the longitudinal direction may be between 70 degrees and 90 degrees, in particular between 75 and 85 degrees, in particular about 84 degrees. The angle may refer to the angle on the crimped sheet before the sheet is gathered. The interruption bands may be inclined with respect to a direction orthogonal to the longitudinal direction.

Each interruption band may comprise a leading portion and a trailing portion. The leading portion may be arranged at a different location than the trailing portion with respect to the longitudinal direction. Each interruption band may have two or more trailing portions. Each interruption band may have two or more leading portions.

The leading portion and the trailing portion may be arranged adjacent to opposite edges of the gathered sheet with respect to the width of the gathered sheet. The leading portion and the trailing portion may be arranged adjacent to opposite edges of the crimped sheet with respect to the width of the crimped sheet before the sheet is gathered. The leading portion may be arranged at a first side of the crimped sheet. The trailing portion may be arranged at a second side of the crimped sheet. The first side may be arranged on one end of the extension of the crimped sheet orthogonal to the longitudinal direction. The first side may be arranged on the other end of the extension of the crimped sheet orthogonal to the longitudinal direction.

Each interruption band may extend primarily along a main path, referred to as primary extension of the interruption band. A secondary extension of the interruption band may be the extension of the interruption band in the longitudinal direction. The direction of the primary extension may be different from the direction of the secondary extension. The corresponding main paths of adjacent interruption bands may be parallel to each other. The corresponding main paths of adjacent interruption bands may be offset by a distance in the longitudinal direction.

Each main path, also referred to as the main path, may start at a path start point adjacent to a first side. The main path may end at a path end point adjacent to a second side. The first side and the second side may be arranged on opposite sides with respect to the width of the gathered sheet or crimped sheet. The direction of the main path may change along its extension from the path start point to the path end point. The main path may have a chevron shape. The main path may have a triangle shape. All main paths may be parallel to each other. All main paths may extend predominantly in the same direction.

The distance between two adjacent interruption bands in the longitudinal direction may be greater than the extension of an interruption band in the longitudinal direction.

The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 5, in particular between 1 and 3, in particular about 2. The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 2, between 1 and 3, between 2 and 4 or between 3 and 5. The ratio of the longitudinal distance between two adjacent interruption bands to the interruption band width may be between 0.5 and 1, between 1 and 2, between 2 and 3, between 3 and 4 or between 4 and 5.