Elastic contact elements for winding a sheet around a group of segments

Abstract

A wrapping device 1 for wrapping a sheet 3 around a group of segments 5 includes a wrapping conveyor 7 and a contact element 25. The wrapping conveyor 7 includes a conveyor surface 9 for receiving the group of segments 5. The contact element 25 provides a facing surface 31. The facing surface 31 is disposed a short distance away from the conveyor surface 9 of the wrapping conveyor 7. The facing surface 31 faces the conveyor surface 9 of the wrapping conveyor 7. The facing surface 31 is configured to engage the group of segments 5 and the sheet 3 when the group of segments 5 is moved along the facing surface 31 by the wrapping conveyor 7, causing the group of segments 5 to rotate and wrap the group of segments 5 with the sheet 3. At least a first portion 41 of the contact element 25, including at least a first portion 35 of the facing surface 31, is formed from a first material that is a resilient material having a Shore hardness of 30A to 70A.

Description

[Technical field]

[0001] The present invention relates to winding a sheet around a group of segments. In particular, the present invention relates to winding a sheet around a group of segments to produce a rod-shaped article. The rod-shaped article may be, for example, a smoking article. [Background technology]

[0002] WO 2015 / 022347 A2 discloses a method for manufacturing a smoking article. An assembly of segments is arranged in an end-to-end relationship, and the outer periphery of the assembly is longitudinally attached to an edge portion of a strip of wrapping material. The assembly of segments provided with the strip of wrapping material is fed to a rolling sheet arranged in a peripheral surface of a wrapping conveyor. A holding surface is provided at a distance from and opposite the peripheral surface of the wrapping conveyor. The assembly of segments is wrapped with the strip of wrapping material by moving the wrapping conveyor relative to the holding surface. The rolling sheet thereby provides the assembly of segments with two guiding contacts and the holding surface provides the assembly of segments with one guiding contact. The three-point guiding contact for the assembly of segments is intended to provide a reliable and safe guiding and wrapping process under controlled conditions. It is stated that providing a three-point guide contact makes the wrapping method particularly suitable for assemblies with rigid, incompressible segments, since the wrapping material remains constantly taught around the outer surface of the assembly of segments due to the constant pressure that can be applied to three points simultaneously.

[0003] US Patent Application Publication No. 2015 / 0291301 A1 discloses a rotatable drum for use in an automated manufacturing process of an e-vapor device. A roll surface of a drum body of the rotatable drum defines a plurality of pockets therein. A sheet structure is mounted within each of the pockets of the drum body to define a grove facing outwardly from the drum body to receive and hold a cartridge of the e-vapor device. The sheet structure includes a material that is more structurally yielding than a material of the cartridge of the e-vapor device. A vacuum port is provided within the sheet structure to provide a retention force for holding the cartridge within the sheet structure. The yieldable nature of the elastic material of the sheet structure promotes a more complete sealing of the cartridge at the vacuum port, which enhances the vacuum retention force applied to the cartridge.

[0004] British Patent No. 2 148 692 A describes a device for attaching two cylindrical tobacco columns to a rigid double-length mouthpiece located in between, by wrapping a sheet of tipping material around the rigid double-length mouthpiece and a portion of each tobacco column to form a cigarette group. It is stated that due to the rigid mouthpiece being made of a smooth and hard plastic material with a relatively low coefficient of friction, the double-length mouthpiece-tobacco column group tends to slide rather than roll through the rolling device, resulting in an incomplete winding. It is further stated that increasing the force applied by the rolling device on the mouthpiece increases the friction between the rolling device and the mouthpiece, while if too much force is applied against the mouthpiece, the mouthpiece will crack. It is proposed to use a stationary rolling block with an intermediate contact zone for engaging the rigid mouthpiece and side contact zones for engaging the double-length cigarette portions extending on both sides of the mouthpiece. The intermediate contact zone and the lateral contact zones are coextensive with each other. The intermediate contact zone is made of a relatively soft, elastic material that has a relatively high coefficient of friction with the mouthpiece to avoid slippage of the mouthpiece during rolling.

[0005] Other machines for producing smoking articles are known, for example from US Pat. Nos. 3,036,581 A and 3,527,234 A. Summary of the Invention [Problem to be solved by the invention]

[0006] It is desirable to provide a way of winding a sheet around a group of segments which results in better results for segments with different properties. It is desirable to provide a way of winding a sheet around a group of segments which improves the quality of the rolled product. It is desirable to provide a highly reliable way of winding a sheet around a group of segments. It is desirable to provide a way of winding a sheet around a group of segments which can be implemented in a structurally simple manner. There is a need for an improved way of winding a sheet around a group of segments which includes at least one rigid segment. There is a need for an improved way of winding a sheet around a group of segments where at least one of the segments has different physical properties than at least another one of the segments. There is a need to provide an improved way of winding a sheet around a group of segments to form a smoking article. [Means for solving the problem]

[0007] According to one aspect, the present invention provides a wrapping apparatus for winding a sheet around a group of segments. The wrapping apparatus comprises a wrapping conveyor and a contact element. The wrapping conveyor comprises a conveyor surface for receiving the group of segments. The contact element provides a counter surface. The counter surface is disposed at a distance relative to a conveyor surface of the wrapping conveyor. The counter surface faces the conveyor surface of the wrapping conveyor. The counter surface is configured to engage the group of segments and the sheet when the group of segments is moved along the counter surface by the wrapping conveyor to cause rotation of the group of segments and wind the sheet around the group of segments. The contact element has a first portion comprising at least a first portion of the counter surface. The first portion of the contact element is formed by a first material. The first material is a resilient material having a Shore hardness of between 30A and 70A.

[0008] The Shore hardness of the first material, and any other Shore hardness described herein, may be determined according to ASTM D2240. Shore hardness is a measure of how deeply a standardized hold-down tool penetrates into a material when pressed into the material with a given force and under specified test conditions.

[0009] Due to the first material being elastic and having a Shore hardness of 30A to 70A, the first portion of the opposing surface may exhibit behavior that automatically adapts to the properties of one or more segments in contact with the first portion of the opposing surface during the process of winding the group of segments between the conveyor surface and the opposing surface.

[0010] The rigid segment may compress the first material. The compression of the first material may reduce the tension of the rigid segment during the rolling process between the conveyor surface and the opposing surface. Damage to the rigid segment during the rolling process may be less likely to occur. Furthermore, the static friction between the rigid segment and the opposing surface may be improved, thereby improving rolling efficiency. An example of a rigid segment is a heat source for a smoking article, or a carbon-based heat source for a smoking article, or a rigid mouthpiece for a smoking article.

[0011] The segment including the relatively compressible material may not compress the first material or may compress the first material to a lesser extent than the rigid segment. The segment including the relatively compressible material may be compressed during rolling between the conveyor surface and the first portion of the opposing surface. After rolling is completed, the segment including the relatively compressible material may return to its initial configuration, thereby tightening the sheet wrapped around the group of segments. An example of a segment including a relatively compressible material is a column of tobacco material, or a compressible filter for a smoking article.

[0012] It may be beneficial if the first portion of the opposing surface engages at least one rigid segment, since the first material may act to prevent damage to the rigid segment during rolling, however, the first portion of the opposing surface may alternatively or additionally engage at least one segment comprising a relatively compressible material.

[0013] The first material may have a Shore hardness of 30A to 60A, or a Shore hardness of 30A to 50A, or a Shore hardness of 40A to 50A.

[0014] The first material may have a Young's modulus of elasticity less than 20 MPa, or less than 15 MPa, or less than 10 MPa, or less than 5 MPa, or less than 3 MPa, or less than 2.5 MPa.

[0015] The first portion of the contact element may have a thickness of at least 1 mm, or at least 2 mm, or at least 4 mm, or at least 6 mm, or at least 8 mm, or at least 10 mm. The thickness of the first portion of the contact element may be sufficient to allow a segment of the group of segments to deform the first portion of the contact element sufficiently to avoid damage to the segment.

[0016] The second portion of the contact element may include a second portion of the facing surface. The second portion of the facing surface may be different from the first portion of the facing surface. The second portion of the contact element may have different elastic properties than the first portion of the contact element. The first portion of the contact element and the second portion of the contact element may be arranged to contact the group of segments at different locations. The first portion of the contact element and the second portion of the contact element may be arranged to contact different segments of the group of segments. The first portion of the contact element and the second portion of the contact element may exhibit different deformation properties.

[0017] Providing different portions of the contact element exhibiting different elastic properties may ensure that different locations in the group of segments are presented with portions of the counter surface having different properties during rolling. The counter surface may be specifically designed to suit the particular requirements of each group of segments.

[0018] The first part of the contact element and the second part of the contact element may be formed from the same material, in which case the contact element may be particularly simple to manufacture.

[0019] Alternatively, the first portion of the contact element and the second portion of the contact element may be formed by different materials. This may facilitate appropriately adjusting the elastic properties of the first portion of the contact element and the elastic properties of the second portion of the contact element. The second portion of the contact element may be formed by a second material. The second material may be different from the first material. The second material may have a higher Shore hardness than the first material. The second material may have a Shore hardness of up to 100 A, or up to 90 A, or up to 80 A, or up to 70 A.

[0020] The first portion of the contact element and the second portion of the contact element may have different thicknesses. Adjusting the thickness of a portion of the contact element may affect the reaction of that portion of the contact element when a segment of the group of segments is pressed onto that portion of the contact element. For example, if the thickness of the portion of the contact element is increased, it may be easier for a segment of the group of segments to deform that portion of the contact element.

[0021] The wrapping conveyor may comprise rotatable rollers. The rotatable rollers may have a circumferential surface defining a conveyor surface for receiving the group of segments. Alternatively, the wrapping conveyor may comprise a linear conveyor. The linear conveyor may comprise at least one conveyor belt or linearly movable element defining a conveyor surface for receiving the group of segments.

[0022] The shape of the counter surface provided by the contact element may follow the shape of the conveyor surface of the wrapping conveyor. For example, if the conveyor surface of the wrapping conveyor essentially corresponds to the circumferential surface of a cylinder, the counter surface may follow a corresponding arc shape. For example, if the conveyor surface of the wrapping conveyor is planar, the counter surface provided by the contact element may also be planar.

[0023] The distance between the conveyor surface of the wrapping conveyor and the facing surface provided by the contact element may be within the range of the maximum diameter of the group of segments, or may be smaller than it. For example, the distance between the conveyor surface of the wrapping conveyor and the facing surface provided by the contact element may be at least 0.7 times the maximum diameter of the group of segments, or at least 0.8 times the maximum diameter of the group of segments, or at least 0.9 times the maximum diameter of the group of segments.

[0024] The conveyor surface may define a groove for receiving the group of segments. The groove may be oriented perpendicular to a direction of conveyance of the group of segments. The group of segments may be rotated within the groove as the group of segments is moved along the opposing surface by the wrapping conveyor. The segments of the group of segments may be received within the groove in an end-to-end relationship. The segments of the group of segments may be positioned side-by-side along an extension of the groove.

[0025] Friction between the group of segments and the groove may be lower than friction between the group of segments and the contact element. Friction between the sheet and the groove may be lower than friction between the sheet and the contact element.

[0026] The diameters of the segments in a group of segments may be the same or essentially the same for all segments. The maximum deviation between the diameters of different segments in a group of segments may be less than 5 mm, or less than 4 mm, or less than 3 mm, or less than 2 mm, or less than 1 mm.

[0027] A segment of the group of segments may be an essentially rod-shaped segment. A segment of the group of segments may be essentially cylindrically shaped. A segment of the group of segments may be a segment of a smoking article.

[0028] At least a portion of the conveyor surface of the wrapping conveyor may be formed by a third material. The third material may be an elastic material. The third material may have a Shore hardness of 30A to 70A. The third material may be the same as the first material. The third material may be the same as the second material. The third material may be susceptible to deformation by one or more of the group of segments during the process of winding the group of segments between the conveyor surface and the counter surface. If the segment has the ability to deform the third material, the likelihood of damaging the segment during the winding process may be reduced.

[0029] The wrapping device may further comprise a heater configured to heat the contact element. The heater may be integrated into the contact element. The heater may be configured to heat the opposing surface of the contact element. The heater may comprise, for example, an electrical resistance heating element or a radiant heater. The heater may be configured to heat the opposing surface of the contact element to a temperature between 40 degrees Celsius and 80 degrees Celsius, or between 40 degrees Celsius and 70 degrees Celsius, or between 40 degrees Celsius and 60 degrees Celsius. Heating the contact element may dry the group of segments and the sheet during the rolling process. Additionally, heating the contact element may contribute to curing an adhesive that secures the sheet to the group of segments.

[0030] The present invention also provides a system for manufacturing smoking articles, the system comprising a wrapping device for wrapping a sheet around a group of segments as described herein, the system further comprising the sheet and a group of segments, the group of segments may comprise segments of smoking articles.

[0031] The segments of the smoking article may include one or more of a segment comprising a heat source for the smoking article, a segment comprising tobacco material, a segment comprising a filter for the smoking article, and a segment comprising a mouthpiece for the smoking article.

[0032] The sheet may be a sheet of any suitable material. For example, the sheet may comprise a paper material. The sheet may be a coated sheet. For example, the sheet may be a sheet of metallized paper. The sheet may be coated with a polymer.

[0033] The invention also provides a method of winding a sheet around a group of segments. Wrapping apparatus and systems according to the invention may be adapted, designed and configured to carry out the method. Features described in the context of a wrapping apparatus or system may also be used to describe the method and vice versa.

[0034] The method includes driving a wrapping conveyor to transport the group of segments on a conveyor surface of the wrapping conveyor and run along opposing surfaces of the contact elements facing the conveyor surface, the group of segments engaging the opposing surfaces and thereby being rotated, whereby the group of segments is wrapped with the sheet, and at least rigid segments of the group of segments elastically deform the opposing surfaces away from the conveyor surface.

[0035] The elastic deformation of the counter surface away from the conveyor system may accommodate the force exerted on the rigid element during the rolling process. Accommodating at least a portion of the force may reduce the possibility of damaging the rigid segment during rolling of the rigid element between the conveyor surface and the counter surface. Furthermore, when the rigid segment deforms the counter surface away from the conveyor surface, there may be particularly good static friction between the rigid segment and the counter surface, thus facilitating the rolling of the sheet around the group of segments between the conveyor surface and the counter surface.

[0036] The deformation of the opposing surface by the rigid segment may be such that the deformation of the opposing surface increases the distance between at least a portion of the deformed section of the opposing surface and the conveying surface by at least 0.1 mm, or by at least 0.3 mm, or by at least 0.5 mm, or by at least 0.7 mm, or by at least 1 mm.

[0037] The rigid segment may be a segment of a smoking article. The rigid segment may comprise a non-cuttable object.

[0038] The rigid segment may comprise a heat source. The heat source may be a heat source for a smoking article. The heat source may have the shape of a cylindrical plug. The heat source may comprise carbon particles. The heat source may comprise a compressed powder of crushed carbon elements. The heat source may comprise an oxidizer. The heat source may be an electrical heat source, or a combustible heat source, or a chemical heat source.

[0039] The present invention is particularly advantageous when rolling a group of segments that includes a rigid segment that is a carbon-based heat source for a smoking article. The carbon-based heat source for a smoking article may be particularly susceptible to damage during the rolling process. For example, the application of excessive pressure during rolling may break the heat source during the rolling process, or may damage the heat source by compressing the component particles of the heat source, so that gases generated in the heat source during combustion in the heat source may have difficulty leaving the heat source.

[0040] The group of segments may include, in addition to the rigid segments, one or more of a segment comprising tobacco material, a segment comprising a filter for a smoking article, and a segment comprising a mouthpiece for a smoking article.

[0041] The elasticity of the facing surface may vary for different portions or regions of the facing surface. For example, a portion of the facing surface in contact with a rigid segment may be more easily deformable than a portion of the facing surface in contact with a segment comprising a relatively compressible material. This may help ensure that the coaxial alignment of the segments in a group of segments is maintained during the process of wrapping the sheet around the group of segments.

[0042] The present invention further provides the use of a contact element having at least a first portion made of an elastic material having a Shore hardness of 30 A to 70 A as a facing surface for winding a group of segments into a sheet of wrapping material. The use of the contact element may be applied for manufacturing smoking articles.

[0043] The elasticity of the facing surface may vary for different portions or regions of the facing surface. For example, a portion of the facing surface in contact with a rigid segment may be more easily deformable than a portion of the facing surface in contact with a segment comprising a relatively compressible material. Features described with respect to the wrapping apparatus, the system for manufacturing smoking articles, and the method for wrapping a sheet around a group of segments may also be used to describe the use of the contact elements.

[0044] In the following the invention is further described by describing embodiments with reference to the drawings. [Brief description of the drawings]

[0045] [Figure 1] FIG. 1 shows a schematic side view of a wrapping apparatus according to one embodiment. [Diagram 2] FIG. 2 shows a top view on the conveying surface of a wrapping conveyor of a wrapping apparatus according to the embodiment described above, showing two grooves occupied by groups of segments and one empty groove. [Diagram 3] FIG. 3 shows a schematic view on the facing surfaces provided by the contact elements of the wrapping device according to the embodiment described above. [Figure 4] FIG. 4 shows diagrammatically a sheet being wrapped around a group of segments between a conveyor surface and a counter surface in a wrapping apparatus according to the previously described embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] 1 shows a schematic side view of a wrapping apparatus 1 according to one embodiment. The wrapping apparatus 1 is configured for winding a sheet 3 around a group of segments 5. The segments of the group of segments 5 may be, for example, cylindrically shaped or rod shaped. The segments of the group of segments 5 may be longitudinally aligned with one another in an end-to-end relationship when wrapped around the sheet 3. The wrapping apparatus 1 comprises a wrapping conveyor 7 for receiving the group of segments 5. In the illustrated embodiment, the wrapping conveyor 7 comprises rotatable rollers defining on its outer circumferential surface a conveyor surface 9 for receiving the group of segments 5.

[0047] FIG. 2 shows a plan view on the conveyor surface 9 of the wrapping conveyor 7. The conveyor surface 9 defines grooves 11 extending parallel to the axis of rotation 13 (see FIG. 1) of the wrapping conveyor 7. Each of the grooves 11 is configured to receive a group 5 of segments to be wrapped with the sheet 3. In FIG. 2, the two leftmost grooves 11 are occupied by a group 5 of segments, respectively. The rightmost groove 11 is empty. In the illustrated embodiment, the group 5 of segments comprises segments of smoking articles. In the groove 11, the segments of the group 5 of segments are arranged side-by-side in an end-to-end relationship.

[0048] According to the embodiment illustrated in FIG. 2, the group of segments 5 includes a cap segment 15 comprising a removable cap for a smoking article, a heat source segment 17 comprising a heat source for the smoking article, a tobacco material segment 19 comprising tobacco material, and a diffuser segment 21 comprising a diffuser for the smoking article. The group of segments 5 may additionally, or as an alternative to one of the illustrated segments, include a filter segment comprising a filter for the smoking article. The group of segments 5 may additionally, or as an alternative to one of the illustrated segments, include a mouthpiece segment comprising a mouthpiece for the smoking article. By winding the sheet 3 around the group of segments 5, the segments of the group of segments 5 are combined. The group of segments 5 may include all the required segments of the smoking article. Alternatively, the group of segments 5 may include only a subset of all the segments required for the manufacture of the smoking article, and additional segments may be added in a subsequent step. In the illustrated embodiment, a portion of the smoking article is formed by winding the sheet 3 around the cap segment 15, the heat source segment 17, the tobacco segment 19, and the diffuser segment 21. The filter segment and mouthpiece segment are then added in a separate winding step, although it would be contemplated to include the filter segment and mouthpiece segment in the first winding step.

[0049] The sheet 3 to be wrapped around the group of segments 5 is also received on the conveyor surface 9 of the wrapping conveyor 7. The leading edge of the sheet 3 may reach into the groove 11 and be placed under the group of segments 5 received in the groove 11. The leading edge of the sheet 3 is preferably glued to the group of segments 5 to establish an initial connection between the group of segments 5 and the sheet 3. The sheet 3 may be cut from a supply roll, provided with strips of adhesive at its leading and trailing edges and fed to the conveyor surface 9 of the supply roll 7, so that the leading edge of the sheet 3 reaches into the groove 11 of the conveyor surface 9. The group of segments 5 may then be deposited in the groove 11 of the conveyor surface 9 to contact the strip of adhesive at the leading edge of the sheet 3. Alternatively, the sheet 3 and the segments of the group 5 may first be glued together and then fed to the conveyor surface 9 as a unit. After the sheet 3 is wrapped around the group of segments 5, as described below, the sheet will be secured by the strip of adhesive at the trailing edge of the sheet 3.

[0050] To ensure adhesion between the sheet 3 and the conveyor surface 9 during rotation of the wrapping conveyor 7, the conveyor surface 9 is provided with suction holes 23. The sheet 3 is held on the conveyor surface 9 under pressure applied to the suction holes 23. Suction holes 23 may be provided in the grooves 11 of the conveyor surface 9 and between the grooves 11 of the conveyor surface 9.

[0051] The wrapping device 1 further comprises a contact element 25. The contact element 25 comprises a main body 27 and a contact body 29 attached thereto. The contact body 29 presents a facing surface 31. The facing surface 31 is disposed at a distance relative to the conveyor surface 9 of the wrapping conveyor 7. The facing surface 31 extends essentially parallel to the conveyor surface 9 of the wrapping conveyor 7 and faces the conveyor surface 9 of the wrapping conveyor 7.

[0052] When the group of segments 5 is transported by the rotation of the wrapping conveyor 7 between the conveyor surface 9 of the wrapping conveyor 7 and the opposing surface 31 of the contact element 25, the group of segments 5 engages the opposing surface 31 of the contact element 25. When the group of segments 5 is moved along the opposing surface 31 of the contact element 25 by the continued rotation of the wrapping conveyor 7, the friction between the opposing surface 31 of the contact element 25 and the group of segments 5 causes the group of segments 5 to rotate about its own axis, thereby wrapping the sheet 3 around the group of segments 5. When the group of segments 5 leaves the gap between the wrapping conveyor 7 and the contact element 25, the sheet 3 is completely wrapped around the group of segments 5. Downstream of the contact element 25, the group of segments 5 wrapped with the sheet 3 may be transferred from the wrapping conveyor 7 to another conveyor 27 for further processing.

[0053] The contact element 25 is provided with a heater 33 for heating the contact element 25. This may contribute to the drying of the group of segments 5 and the hardening of the adhesive strips.

[0054] Figure 3 shows a plan view on the counter surface 31 of the contact element 25. The left-right direction in Figure 3 corresponds to the conveying direction in which the group of segments 5 is moved along the counter surface 31. The up-down direction in Figure 3 corresponds to the direction in which the segments of the group of segments 5 are arranged side by side. The up-down direction in Figure 3 is parallel to the axis of rotation 13 of the wrapping conveyor 7.

[0055] In the illustrated embodiment, the facing surface 31 of the contact element 25 is divided into three parts. A first part 35 of the facing surface 31 is arranged to contact the cap segment 15 and the heat source segment 17 of the group of segments 5. A second part 37 of the contact surface 31 is arranged to contact the tobacco segment 19 of the group of segments 5. A third part 39 of the facing surface 31 is arranged to contact the diffuser segment 21 of the group of segments 5. The first part 35 of the facing surface 31 is defined by a first part 41 of the contact element 25. The second part 37 of the facing surface 31 is defined by a second part 43 of the contact element 25. The third part 39 of the facing surface 31 is defined by a third part 45 of the contact element 25. The first part 41, the second part 43, and the third part 45 of the contact element 25 are parts of the contact body 29 of the contact element 25.

[0056] The first portion 41 of the contact element 25 is formed by a first material. The first material is a material having a Shore hardness of 30A to 70A. According to an embodiment, the first material may have a Shore hardness of 30A to 60A, or a Shore hardness of 30A to 50A, or a Shore hardness of 40A to 50A. The first material may have a Young's modulus of elasticity of less than 20 MPa, or less than 15 MPa, or less than 10 MPa, or less than 5 MPa, or less than 3 MPa, or less than 2.5 MPa. The first portion of the contact element may have a thickness of at least 1 mm, or at least 2 mm, or at least 4 mm, or at least 6 mm, or at least 8 mm, or at least 10 mm.

[0057] 4 shows a cross-sectional view illustrating the engagement between the heat source segment 17 of the group of segments 5 and the first portion 35 of the counter surface 31 during the winding of the sheet 3 around the group of segments 5. Due to the material properties of the first portion 41 of the contact element 25, the heat source segment 17 may deform the first portion 35 of the counter surface 31 away from the conveyor surface 9. The heat source segment 17 may penetrate into the first portion 41 of the contact element 25. This may protect the heat source segment 17 from being damaged due to too much pressure exerted on the heat source segment 17 with the winding process between the conveyor surface 9 and the counter surface 31.

[0058] The second portion 43 of the contact element 25 may have different elastic properties than the first portion 41 of the contact element 25. The second portion 43 of the contact element 25 may be formed by a second material having a higher Shore hardness than the first material. In particular, the Shore hardness of the second material may be higher than that of the first material, but cannot exceed 90A or 100A. The second portion 37 of the facing surface 31 comes into contact with the tobacco segment 19 during the process of winding the sheet 3 around the group of segments 5. The tobacco segment 19 may itself be compressible. This may be advantageous if the tobacco segment 19 is compressed between the conveyor surface 9 and the facing surface 31. There may be no or substantially no deformation of the second portion 37 of the facing surface 31 by the tobacco segment 19 during the process of winding the group of segments 5 between the conveyor surface 9 and the facing surface 31.

[0059] The diffuser segments 21 may be essentially incompressible and may be susceptible to damage due to high pressure exerted on the diffuser segments 21. The third portion 45 of the contact element 25 may have elastic properties similar to those of the first portion 41 of the contact element 25. Specifically, the third portion 45 may also be formed by the first material. The diffuser segments 21 may be configured to elastically deform the third portion 39 of the facing surface 31 away from the conveyor surface 9 in association with the process of wrapping the sheet 3 around the group of segments 5 between the conveyor surface 9 and the facing surface 31.

[0060] According to one embodiment, the first portion 41 of the contact element 25, the second portion 43 of the contact element 25, and the third portion 45 of the contact element 25 may have the same thickness. Alternatively, at least two of the first portion 41 of the contact element 25, the second portion 43 of the contact element 25, and the third portion 45 of the contact element 25 may have different thicknesses. For example, the thickness of the first portion 41 of the contact element 25 may be greater than the thickness of the second portion 43 of the contact element 25. The first portion 41 of the contact element 25 may have a greater thickness to allow deformation of the first portion 35 of the facing surface 31 away from the conveyor surface 9. The second portion 43 of the contact element 25 does not need to be deformed and may therefore have a smaller thickness.

[0061] According to the embodiment shown in Figure 4, the main body 47 of the wrapping conveyor 7 may be covered with a layer of elastic material 49. The layer of elastic material 49 may be made of a third material. The third material may for example be identical to the first material or to the second material.

Claims

1. 1. A wrapping device for wrapping a sheet around a group of segments, comprising: a wrapping conveyor having a conveyor surface for receiving said group of segments; a contact element providing a facing surface, said facing surface being disposed at a distance from the conveyor surface of said wrapping conveyor, said facing surface being configured to face said conveyor surface of said wrapping conveyor and to engage said group of segments and said sheet to cause rotation of said group of segments and to wrap said group of segments with said sheet as said group of segments is moved along said facing surface by said wrapping conveyor, at least a first portion of the contact element comprising at least a first portion of the facing surface is formed of a first material, the first material being a resilient material having a Shore hardness of between 30A and 70A; and a wrapping device, wherein a second portion of the contact element comprises a second portion of the facing surface and has different elastic properties than the first portion of the contact element, and the first portion of the contact element and the second portion of the contact element are arranged to contact the group of segments at different locations.

2. The lapping apparatus of claim 1, wherein the first material has a Shore hardness of between 40A and 50A.

3. 3. The wrapping apparatus of claim 1 or claim 2, wherein the first material has a Young's modulus of elasticity of less than 20 MPa, or less than 15 MPa, or less than 10 MPa, or less than 5 MPa, or less than 3 MPa, or less than 2.5 MPa.

4. A wrapping apparatus according to any one of claims 1 to 3, wherein the first portion of the contact element has a thickness of at least 1 mm, or at least 2 mm, or at least 4 mm, or at least 6 mm, or at least 8 mm, or at least 10 mm.

5. The wrapping apparatus of any one of claims 1 to 4, wherein the first portion of the contact element and the second portion of the contact element have different thicknesses.

6. The wrapping device according to any one of the preceding claims, wherein the second portion of the contact element is formed by a second material having a Shore hardness of at most 100A, or at most 90A.

7. A wrapping apparatus as claimed in any one of claims 1 to 6, wherein the conveyor surface defines a groove for receiving the group of segments, the groove being oriented perpendicular to a direction of transport of the group of segments.

8. 1. A system for producing smoking articles, comprising: A wrapping device for winding a sheet around a group of segments according to any one of claims 1 to 7; The sheet; and a group of said segments comprising segments of a smoking article.

9. The system of claim 8, wherein the segments of the smoking article include one or more of a segment comprising a heat source for the smoking article, a segment comprising tobacco material, a segment comprising a filter for the smoking article, and a segment comprising a mouthpiece for the smoking article.

10. 1. A method of winding a sheet around a group of segments, comprising the steps of: driving a wrapping conveyor to transport the group of segments on a conveyor surface of the wrapping conveyor and along opposing surfaces of contact elements facing the conveyor surface; the group of segments engages the opposing surfaces and is rotated by this engagement so that the group of segments is wrapped with the sheet; A method in which at least a rigid segment of the group of segments elastically deforms the facing surface away from the conveyor surface, the rigid segment comprising a heat source.

11. The method of claim 10 , wherein the rigid segment comprises an uncuttable object.

12. 12. The method of claim 10 or claim 11, wherein the group of segments includes, in addition to the rigid segment, one or more of a segment comprising tobacco material, a segment comprising a filter for a smoking article, and a segment comprising a mouthpiece for a smoking article.

13. The method according to any one of claims 10 to 12, wherein the elasticity of the opposing surface is different in different areas of the opposing surface.

14. 14. A method according to any one of claims 10 to 13, wherein the deformation of the opposing surface by the rigid segments is such that the distance between at least a part of the deformed section of the opposing surface and the conveyor surface increases by at least 0.1 mm, or by at least 0.3 mm, or by at least 0.5 mm, or by at least 0.7 mm, or by at least 1 mm.

15. Use of a contact element having at least a first portion made of an elastic material having a Shore hardness of 30A to 70A as an opposing surface for winding a group of segments into a sheet of wrapping material, wherein the elasticity of the opposing surface varies in different regions of the opposing surface.

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