Method and apparatus for forming a continuous web of material into a rod - Patents.com

Abstract

A method for forming a continuous web material (1) into a rod includes providing a continuous web material (1) having a glass transition temperature of less than 150 degrees Celsius and consolidating the continuous web material from a flat shape into a rod shape with a forming apparatus (2). The method further includes providing a cooling means (34) that provides a temperature of less than 4 degrees Celsius, cooling a material contact surface of the forming apparatus (2) to a surface temperature of less than 4 degrees Celsius, and cooling the consolidation of the continuous web material with the cooled material contact surface in contact with the consolidation of the continuous web material. Also provided is equipment for forming the continuous web material (1).

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for forming a continuous web of material into a rod, and in particular to a method and apparatus for forming a continuous web of material for use in the manufacture of aerosol-generating articles. [Background technology]

[0002] The aerosol-generating article or its components (e.g., filter plugs or aerosol cooling segments, etc.) may be manufactured from continuous web materials, such as cellulose or plastic webs. Due to the special materials used for the manufacture of these segments, some processing steps in the processing line may pose additional challenges when handling such webs. For example, some plastic materials (e.g., polylactic acid webs, etc.) tend to heat up during handling of the web, e.g., due to friction. This may lead to irregular folds, e.g., funnel-shaped webs, thereby reducing the reproducibility of products manufactured from the web. Summary of the Invention [Problem to be solved by the invention]

[0003] In the manufacture of aerosol-generating articles, it is desirable to provide a method and equipment for forming a continuous web of material. [Means for solving the problem]

[0004] According to the present invention, there is provided a method for forming a continuous web material into a rod. The method includes providing a continuous web material having a glass transition temperature of less than 150 degrees Celsius and assembling the continuous web material from a flat shape to a rod shape by a forming apparatus. The method further includes providing a cooling means for providing a temperature of less than 4 degrees Celsius, cooling a material contact surface of the forming apparatus to a surface temperature of less than 4 degrees Celsius, and cooling the assembly of the continuous web material with the cooled material contact surface in contact with the assembly of the continuous web material. Preferably, the method includes cooling the assembly of the continuous web material to a material temperature of less than 4 degrees Celsius, especially when the web material is in direct contact with the material contact surface.

[0005] The cooling means may be any means for cooling the material contact surface to a temperature below 4 degrees Celsius, in particular below 0 degrees Celsius. The cooling means may be, for example, a Peltier element or a cooling fluid. Using a cooling fluid is very efficient in cooling. Using a Peltier element is a simple way of cooling without the need for handling fluids.

[0006] The cooling means is preferably a cooling fluid having a fluid temperature below 4 degrees Celsius, more particularly a fluid temperature below 0 degrees Celsius.

[0007] Friction between the web material and especially the stationary forming apparatus is highest in the final rod-forming section (garniture) of the gathering process. By supercooling the web material, localized overheating of the web material due to friction associated with gathering in the forming apparatus may be essentially prevented.

[0008] Localized overheating is preferably prevented or at least reduced to a temperature of the web material significantly below its melting temperature.Overheating is preferably prevented or reduced to a temperature of the web material significantly below its glass transition temperature.

[0009] The web material is preferably cooled such that the temperature of the web remains at least 10 degrees Celsius below its glass transition temperature. More preferably, the temperature of the web material remains at least 20 degrees Celsius, at least 40 degrees Celsius, or at least 50 degrees Celsius below its glass transition temperature. If the web material has a glass transition temperature of, for example, greater than 100 degrees Celsius, the temperature of the web material when cooled preferably remains even greater than 50 degrees Celsius below its glass transition temperature. For example, if the web material is cooled to a temperature below 4 degrees Celsius as it is formed, the temperature of the web material will drop even greater than about 100 degrees Celsius below its glass transition temperature.

[0010] Excessive heat may change the material specifications. By preventing overheating of materials with low glass transition temperatures, or low melting temperatures, or both, the material may be prevented from becoming sticky or from partially melting. Thus, individual folds of such materials may be prevented from sticking together or fusing together as they assemble. Advantageously, the variation of the resistance to pull (RTD) of the plug formed by the material from a target value may be reduced or completely avoided. This may increase the repeatability of manufacturing. In addition, the sticking of partially melted or sticky materials to equipment parts may be avoided. Thus, possible equipment blockage and withdrawal may be avoided. Alternatively or additionally, damage to the material may be avoided.

[0011] Advantageously, local overheating of the material is avoided, so that the temperature of the web material preferably does not reach, and more preferably does not even approach, the glass transition temperature. Furthermore, the tensile strength of the material may be reduced by heating. This may result in the need to reduce the machine speed to prevent the material from bursting. Machine stoppages and waste due to bursting of the material with reduced tensile strength can therefore be avoided. Thus, preventing or reducing overheating of the material is particularly advantageous for materials with low glass transition temperatures or low melting temperatures, such as, for example, webs of polylactic acid.

[0012] At the glass transition temperature, the solid material changes to a rubbery elastic state, and the solid material becomes a pasty molten material. For example, an amorphous or semi-crystalline plastic material may become sticky and change in its stability. The transition to the rubbery elastic state or the yield range is continuous. At the glass transition temperature, the material does not undergo a phase transition. Therefore, the glass transition temperature is not related to an exact temperature, but to a temperature range. Such a temperature range may be within a few degrees Celsius above or below a particular glass transition temperature, for example within 5 degrees Celsius, or within a few tens of degrees Celsius, for example within plus or minus 20 degrees Celsius.

[0013] It is also known that continuous materials, when cooled to very low temperatures, can become brittle and can inadvertently break when handled. However, it has been found that web materials cooled by a cold contact surface do not inadvertently break, or break only to a very limited extent, as compared to cooling by direct contact with a cooling fluid. In addition, cooling by contact with a cold contact surface has the advantage of cooling the web material exactly where friction occurs (the interface between the forming device and the continuous web material assembled in the forming device).

[0014] Still further, in the final rod forming area, there are stringent precision requirements regarding the diameter of the rods, which are difficult to maintain under the varying compressive strengths of the cooling fluid introduced into the web material, but may be well achieved using cooling surfaces.

[0015] It has also been found that using cooling means providing a cooling temperature of less than 4 degrees Celsius and cooling the contact surface to a temperature of less than 4 degrees Celsius and also cooling the web material at the cooled contact surface, preferably also to a temperature of less than 4 degrees Celsius, provides very good results in preventing overheating of web materials having low glass transition temperatures (such as polylactic acid materials) during assembly. In particular, it has been found that good results in preventing overheating of web materials having low glass transition temperatures may be achieved by using cooling means providing a cooling temperature of less than 0 degrees Celsius (e.g., between minus 0 degrees Celsius and minus 5 degrees Celsius).

[0016] It has been found that this approach provides very good results in stationary forming elements, in particular in stationary funnel-shaped forming devices having production speeds of about 200 to 500 meters per minute.

[0017] The term "cooling" is used throughout this specification to refer to an active process of limiting, maintaining, or reducing the temperature of a continuous web material, the temperature of a cross-section of the continuous web material, or the temperature of an element in contact with the continuous web material, thus preventing a further increase in the temperature of the continuous web material.

[0018] The terms "upstream" and "downstream" are used herein with respect to the direction of transport of a continuous web of material in a facility or in a particular piece of equipment where the process is carried out, downstream being in the direction of production.

[0019] As a general rule, whenever the term "about" is used throughout this specification in connection with a particular value, it is understood that the value following the term "about" does not have to be strictly that particular value due to technical considerations. However, it is understood that the term "about" used in connection with a particular value always includes and explicitly discloses the particular value following the term "about."

[0020] The term "gathering" is used throughout this specification to refer to a reduction in the width of a continuous web of material. By gathering, the continuous material is reduced laterally across the material, and therefore transverse to the longitudinal and conveying direction of the material. Gathering may be, for example, compacting, funneling, and rod forming of the material, or a combination of the aforementioned processes. Gathering includes a reduction in the width of a continuous web of material, for example, by simply pushing the sides of the continuous material against the longitudinal central axis of the continuous material.

[0021] The assembly may be performed continuously or in stages. The assembly may be performed in one section of the molding apparatus or in several sections.

[0022] The gathered material as used herein may be a partially gathered material or a final gathered material. The partially gathered material has a reduced width compared to the continuous web material as it is fed into the equipment carrying out the method according to the invention. The partially gathered material may also have a reduced width compared to the partially gathered material that has already passed through a previous part of the forming apparatus. The partially gathered material has a width that is greater than the width of the final rod shape of the continuous material. Often, the reduction in the width of the web material leads to an increase in the height of the gathered material.

[0023] Preferably, the gathering includes forming longitudinal folds that form channels along the longitudinal axis of the gathering of web material.

[0024] It may be advantageous to crimp the web material prior to collection. In particular, crimping may improve control over the way the web material is collected. Crimping is a process in which corrugations are introduced into the web material. The crimp depth of the corrugations may be varied and may be quantified as the amplitude of the corrugations.

[0025] Preferably, the crimped web material has a corrugation depth (or crimp depth) of from 50 micrometers to 300 micrometers, more preferably from about 100 to about 250 micrometers.

[0026] Cooling of the continuous web material in the forming apparatus by the cooled contact surface also supports the gathering or shaping process. The material contact surface is part of the forming apparatus and has a shape that is shaped to form the continuous web material to that shape or that is shaped to hold the continuous web material in a particular shape.

[0027] In a staged gathering process, the web material is gathered to a particular rod diameter in a first step, and in further gathering steps the web material is gathered to smaller rod diameters up to the final diameter.

[0028] The final rod shape may have an outer diameter of 5 mm to 12 mm, preferably 6 mm to 10 mm.

[0029] Rods produced using the method of the present invention preferably have a circular or elliptical cross-section.

[0030] The method preferably comprises a stepwise assembly of the continuous web material into a rod shape. In a first assembly step, the method preferably comprises assembly of the continuous web material from a flat shape into a rod shape having a first diameter. In a second assembly step, the method may comprise further assembly of the continuous web material from the rod shape having the first diameter into a final rod shape having a final diameter, the final diameter being smaller than the first diameter.

[0031] In a preferred embodiment, the first diameter is in the range of 2 centimeters to 5 centimeters.

[0032] In a preferred embodiment, the final diameter is a maximum of 12 millimeters.

[0033] The majority of the heat is generated when the continuous web material is most compressed, and therefore when the web material is compressed to its final rod diameter. The continuous web material may be cooled during the first gathering step and during the second gathering step. Preferably, the continuous web material is cooled at least during the second gathering step, and may be cooled only during the second gathering step. Cooling of the material contact surface is achieved by providing a cooling means in thermal contact with the forming apparatus. Cooling of the material contact surface is preferably achieved by providing a cooling fluid into or through the forming apparatus. For example, the cooling fluid may be a cooling liquid, such as a mixture of water and glycol. A mixture of about 50 percent water and about 50 percent glycol is preferably used as the cooling fluid.

[0034] In operation the cooling means provides a cooling temperature of less than 4 degrees Celsius. The cooling means may provide a cooling temperature of less than 2 degrees Celsius, 0 degrees Celsius, less than minus 2 degrees Celsius, less than minus 4 degrees Celsius, less than minus 6 degrees Celsius, less than minus 8 degrees Celsius, less than minus 10 degrees Celsius, less than minus 20 degrees Celsius. Preferably the cooling temperature is in the range of 3 degrees Celsius to minus 45 degrees Celsius, preferably in the range of 3 degrees Celsius to minus 20 degrees Celsius, more preferably in the range of 0 degrees Celsius to minus 10 degrees Celsius.

[0035] If a cooling fluid is used, the cooling fluid has a fluid temperature of less than 4 degrees Celsius. The cooling fluid may have a cooling temperature of less than 2 degrees Celsius, 0 degrees Celsius, less than minus 2 degrees Celsius, less than minus 4 degrees Celsius, less than minus 6 degrees Celsius, less than minus 8 degrees Celsius, less than minus 10 degrees Celsius, less than minus 15 degrees Celsius, less than minus 20 degrees Celsius, or less than minus 20 degrees Celsius. The fluid temperature is preferably in the range of 3 degrees Celsius to minus 30 degrees Celsius, preferably in the range of 3 degrees Celsius to minus 20 degrees Celsius, and more preferably in the range of 0 degrees Celsius to minus 15 degrees Celsius.

[0036] The surface temperature of the material contact surface is less than 4 degrees Celsius. The surface temperature of the material contact surface may be less than 2 degrees Celsius, 0 degrees Celsius, less than minus 2 degrees Celsius, less than minus 4 degrees Celsius, less than minus 6 degrees Celsius, less than minus 8 degrees Celsius, less than minus 10 degrees Celsius, less than minus 15 degrees Celsius, less than minus 20 degrees Celsius, or less than minus 25 degrees Celsius. The surface temperature of the material contact surface is preferably in the range of 4 degrees Celsius to minus 25 degrees Celsius, preferably in the range of 4 degrees Celsius to minus 20 degrees Celsius, more preferably in the range of 0 degrees Celsius to minus 15 degrees Celsius, for example a surface temperature of about minus 5 degrees Celsius.

[0037] Preferably the web material is cooled to a material temperature of less than 4 degrees C. The web material may be cooled to a temperature of minus 30 degrees Celsius to 4 degrees Celsius, minus 20 degrees Celsius to 4 degrees Celsius, or minus 10 degrees Celsius to 0 degrees Celsius.

[0038] The surface temperature of the contact surface is preferably controlled such that the higher the speed of the web material passing over the contact surface, the lower the temperature.

[0039] Preferably, the method comprises the further step of measuring the cooling temperature of the cooling means (eg the cooling temperature of the cooling fluid).

[0040] The method may further comprise the step of providing a funnel for gathering the web material. The funnel may comprise a cooling finger contacting the web material in the area of ​​highest compression. The cooling finger may comprise a reservoir for cooling fluid. Providing a reservoir for cooling fluid may advantageously increase the heat capacity of the cooling finger, especially when the reservoir is filled with cooling fluid. The cooling effect may be further improved by circulating or continuously (or alternatively discontinuously) exchanging the cooling fluid in the reservoir.

[0041] The method may further include providing a cooling bar, which may contact the assembled rods after the cooling funnel.

[0042] The step of measuring the temperature may be performed at or within the reservoir. The step of measuring the temperature may be performed at a cooling bar. Preferably the method includes cooling the fluid in the reservoir to a temperature of between plus 4 degrees Celsius and minus 10 degrees Celsius. Preferably the method includes cooling the fluid at the end of the cooling bar to a temperature of between plus 4 degrees Celsius and minus 10 degrees Celsius.

[0043] Accurate measurement of material temperature of a continuous web material is difficult. Because the assembly and generation of frictional heat can be a rapidly changing process, measurements of material temperature are often not very accurate, especially in terms of local material temperature. For example, in a near-finally assembled rod of continuous web material, there may be a large temperature difference between the center of the rod and a location on the circumference of the rod.

[0044] Therefore, it is preferred to measure the surface temperature of the cooled contact surface. The surface temperature of the cooled contact surface is preferably measured during operation, and therefore preferably during the implementation of the method according to the invention or during the operation of the installation according to the invention. It is preferred to measure the surface temperature of the cooled contact surface while the continuous web material passes through and contacts the cooled contact surface. By measuring and controlling the surface temperature of the contact surface, the material temperature of the collected continuous web material may be controlled following defined material and process parameters. The surface temperature of the cooled contact surface is preferably measured at different locations during the forming process, for example at different locations of the forming device.

[0045] The method is: - wrapping a collection of continuous web material in the form of a rod with a continuous strip of wrapping material provided with adhesive; - cooling a rod contact surface of the rod cooling device using cooling means to a rod contact surface temperature of less than 4 degrees Celsius and contacting a wound rod of an assemblage of continuous web material with the cooled rod contact surface; - cooling the wrapping material provided with adhesive and wound around the rod of the collection of continuous web material by means of a cooled rod contact surface in contact with the wound rod. Preferably, the wrapping material wound around the collection of web material is cooled to a wrapper temperature of less than 4 degrees Celsius.

[0046] After the continuous web material is assembled into its final rod shape, the rod proceeds to a wrapping stage where the adhesive provided wrapping material closes upon itself to wrap the web material and form a wound continuous rod of the web material.

[0047] The wrapper material for wrapping the collection of web materials is provided with an adhesive at least along the seam to close the wrapper around the web materials. Such an adhesive may be heated and then applied to the wrapper material when it is at a high temperature. Alternatively or additionally, the wrapper material may be provided with an adhesive, which is liquefied after heating the wrapper material comprising the adhesive. Regardless of the application process, heat is provided to the wound rod of web material. It has been found that the heat provided after wrapping the rod may have the same adverse effects on the web material as outlined above for heat generated by friction. This is particularly true for web materials with low glass transition temperatures or low melting temperatures. It is therefore preferable to limit the heat provided after wrapping the web material or to avoid the heat progressing to the temperature-sensitive web material. It has been found that conventional cooling of the wound rod (e.g. by air) may stabilize the adhesive on the wrapping material but may not prevent the heat from penetrating into the web material. In particular, it has been found that the effect of heated adhesive on the web material may be reduced or even avoided when the wound rod is cooled by using a cooling means providing a temperature of less than 4 degrees C. In particular, the wound rod may be cooled by contact of a rod contact surface having a rod contact surface temperature of less than 4 degrees C.

[0048] The wrapper is preferably cooled to a wrapper temperature of less than 4 degrees Celsius. The wrapper may be cooled to a temperature of, for example, minus 30 degrees Celsius to 4 degrees Celsius, minus 20 degrees Celsius to 4 degrees Celsius, or minus 10 degrees Celsius to 0 degrees Celsius.

[0049] The reproducibility of the produced continuous rods of web material may be improved by undercooling the continuous web material during assembly, and by undercooling the wound rod of web material after the wrapping material has been wound around the rod and closed. Material parameters may be kept constant or within small variations, and melting of the materials together may be prevented or strongly limited during assembly and wrapping.

[0050] According to the present invention, there is also provided an apparatus for forming a continuous web material into a rod. The apparatus comprises a forming apparatus for forming the continuous web material from a flat shape into a rod shape. The forming apparatus comprises a funnel portion for forming the continuous web material into a rod shape. The forming apparatus comprises a material contact surface for contacting the continuous web material guideable through the funnel portion. The apparatus also comprises cooling means for providing a cooling temperature of less than 4 degrees Celsius. The forming apparatus is in communication with the cooling means and is adapted for cooling the material contact surface of the forming apparatus to a surface temperature of less than 4 degrees Celsius. In which the material contact surface is disposed along a length of the funnel portion of the forming apparatus to cool the continuous web material while it is being assembled within the funnel portion.

[0051] The cooling means is preferably a source of cooling fluid having a temperature of less than 4 degrees C. In these embodiments, the molding apparatus is in fluid communication with the cooling fluid source.

[0052] The installation preferably includes a wrapping device for wrapping the rod-shaped web material with a continuous strip of wrapping material, the wrapping material being provided with an adhesive.

[0053] The equipment preferably includes a rod cooling device having a rod contact surface for contacting the wound rod of web material, the rod cooling device adapted to cool the rod contact surface of the wrapping device to a rod contact surface temperature of less than 4 degrees Celsius, whereby the wrapping material wound around the rod of web material is cooled to a wrapper temperature, preferably to a wrapper temperature of less than 4 degrees Celsius.

[0054] To cool the rod contact surface, the rod cooling apparatus is in fluid communication with a cooling means providing a cooling temperature of less than 4 degrees Celsius. To cool the rod contact surface, the rod cooling apparatus is preferably in fluid communication with a source of cooling fluid having a fluid temperature of less than 4 degrees Celsius.

[0055] The same cooling means providing a cooling temperature of less than 4 degrees Celsius may be used to cool the forming apparatus and to cool the rod cooling apparatus. Separate cooling means may be used for the forming apparatus and for the rod cooling apparatus. The separate cooling means may for example provide different temperatures or may be based on different cooling practices, such as for example the use of cooling means in the form of Peltier elements or cooling fluids.

[0056] For example, the same source of cooling fluid having a fluid temperature of less than 4 degrees Celsius may be used to cool the forming apparatus and to cool the rod cooling apparatus. Separate cooling fluid sources may be used for the forming apparatus and for the rod cooling apparatus. The separate sources of cooling fluid may include cooling fluids having, for example, different temperatures or different fluid compositions.

[0057] The advantages of the equipment for undercooling the web material while it is being gathered and formed into a rod, and preferably also while it is being undercooled after it has been formed into a rod and wound, have already been described in connection with the method according to the invention and will not be repeated.

[0058] Preferably, assembling the continuous web material from a flat shape into a rod shape comprises continuously assembling the continuous web material in a direction perpendicular to the transport direction of the continuous web material, preferably by means of a stationary forming device, which is a particularly simple way of assembling the web material compared to methods using, for example, a moving forming device.

[0059] The forming apparatus preferably comprises a funnel section, at least a portion of which comprises an upper funnel section and a lower conveying plane having converging longitudinally extending grooves.

[0060] The upper funnel section and the lower conveying plane may together form a forming device. The upper funnel section and the lower conveying plane may also at least partially form a forming element. Thus, further forming elements (e.g. an extra funnel section or a crimping device arranged upstream of the forming device) may be provided to form the forming device. The extra funnel section may be, for example, a metal funnel. The funnel is preferably coated or made of an anti-friction material.

[0061] In some embodiments, the upper funnel forms one half of the forming apparatus, for example the upper half. In these embodiments, the lower conveying plane forms the other half of the forming apparatus, for example the lower half of the forming apparatus.

[0062] The upper funnel portion provides a concave circumferential shape to a portion of the continuous web material, and a lower conveying plane or groove extending into the conveying plane closes the funnel portion along the remaining periphery, thereby directing the continuous material into the forming apparatus.

[0063] The funnel portion preferably has an inner concave shape for forcing the continuous web material into a circular or elliptical circumferential shape. In particular, the material contact surface of the forming device, more particularly the upper funnel portion, may have a concave shape. The material contact surface of the forming device preferably has a converging concave shape that converges in the conveying direction of the web material.

[0064] The surface temperature of the material contact surface is preferably measured at one location, and more preferably at two or more locations, on the contact surface.

[0065] The funnel, preferably the extra funnel portion, disposed upstream of the forming device with the cooled contact surface, is provided with a structured surface. The structure may reduce direct contact between the funnel surface and the web material passing through the funnel. This may reduce frictional heat generation. The structure may also reduce the cooling action of the funnel on the web material.

[0066] The surface structure of the funnel is preferably selected such that the contact or lack of contact between the continuous web material and the structured surface of the funnel varies as the web material passes through the funnel. The structure is preferably selected such that the same portion of the web material passing through the structured surface of the funnel is not always in contact or permanently in contact with the structures of the structured surface of the funnel.

[0067] The structures may be regular or irregular, for example wavy line structures, or diverging or converging line structures, or indentation structures, preferably with the indentations being arranged in a transversely displaced manner when viewed along the transport direction of the web material.

[0068] The conveying plane of the forming apparatus may function to support the continuous strip of wrapping material.Preferably the method of forming includes guiding the continuous strip of wrapping material along the conveying plane of the forming apparatus.

[0069] The continuous web material may be disposed on the wrapping material and may be transported in a downstream transport direction on the wrapping material. The grooves in the transport plane are preferably transversely converging concave. The grooves may extend along the entire length of the transport plane or along only a portion of the length.

[0070] The wrapping material forms an inner liner of the groove that partially wraps the assembly of the continuous web material. After the continuous web material is assembled into its final rod shape, the wrapping material is completely wrapped around the rod to secure the rod in its rod shape. Such continuous or fused rod forming and wrapping is particularly preferred for elastic web materials that tend to resist assembly, such as many types of plastic foils.

[0071] Advantageously, the rod cooling device is arranged downstream of the forming device and downstream of the wrapping device. The rod cooling device may also be integrated into the wrapping device or wrapping element, whereby cooling of the wrapping material may occur simultaneously with wrapping or immediately after wrapping.

[0072] The rod contacting surface of the rod cooling device preferably has a concave shape. The shape of the rod contacting surface is preferably constant over the length of the rod cooling device.

[0073] The part of the rod cooling device comprising the rod contact surface is preferably removably mounted above the conveying plane. This allows for observing the wrapping process. The rod contact surface is preferably in contact with the wrapping material. The rod contact surface is preferably in thermal contact with at least the thermally conductive part of the rod cooling device, and the rod contact surface is preferably in thermal contact with the thermally conductive part of the wrapping device.

[0074] The rod contact surface extends along the longitudinal extension of the rod or along the conveying direction. The rod contact surface may have a length in the conveying direction of the web material of about 10 centimeters to about 80 centimeters, preferably about 30 centimeters to about 60 centimeters.

[0075] Preferably, the temperature of the rod contact surface is measured at one location, and more preferably at two or more locations along the length of the rod contact surface.

[0076] The material contact surface extends along the funnel portion in the conveying direction of the web material. The material contact surface may extend from the upstream end of the funnel portion to the downstream end of the funnel portion. In particular, the material contact surface may extend from the upstream end of the upper funnel portion to the downstream end of the upper funnel portion. This allows for undercooling of the continuous web material at the assembly cross section where most friction occurs and where most heat due to frictional forces is generated. The material contact surface may extend from the most upstream end of the forming device to the most downstream end of the forming device. This allows the web material to be cooled during assembly from a flat shape to a final rod shape.

[0077] The material contact surface and the rod contact surface extend at least along a perimeter or part of the perimeter of the mass or rod of web material. The contact surface may extend between about 90 degrees and 360 degrees along the perimeter of the web material. Thus, the cooled contact surface may partially or completely surround the web material. Preferably, the contact surface extends at least about 90 degrees along the perimeter of the web material. More preferably, the contact surface extends at least about 180 degrees along the perimeter of the web material. Preferably, the contact surface is cooled by thermal contact with a cooling means, preferably a cooling fluid.

[0078] An actively cooled piece of equipment may be in thermal contact with another piece of equipment, whereby the contact surface may be cooled by thermal contact with the actively cooled piece of equipment.

[0079] Preferably, the actively cooled upper funnel portion is in thermal contact with the conveying plane. The groove in the conveying plane that serves as the lower contact surface for the web material (possibly by a strip of wrapping material disposed below the web material) may be cooled by thermal contact with the upper funnel portion. This allows a 360 degree cooling contact surface to be available for the web material that is gathered between the upper funnel portion and the lower conveying plane.

[0080] The equipment parts that are in thermal contact with the contact surface are preferably made of good heat conductors, for example metal.The thermally conductive materials used for the cooling element or the connecting parts and contact surfaces of the cooling element preferably have a thermal conductivity of at least 10 W / mK.The thermally conductive materials used for cooling the web material in the equipment of the present invention preferably have a thermal conductivity of at least 200 W / mK.

[0081] A continuous web material as used herein is, for example, a web of material used in the manufacture of an aerosol-generating article, such as an aerosol-generating article for an electronic smoking device. The continuous web material is preferably a plastic web, such as a continuous web of polylactic acid. The continuous web material may be an aerosol-forming substrate.

[0082] In some embodiments, the continuous web material may be soaked or impregnated with an aerosol-forming material. Such a continuous web material may be a non-aerosol-forming substrate. The soaking or impregnation may be performed before crimping the continuous web material, or before or during assembly. Preferably, upon heating of the aerosol-forming substrate, or of the continuous web material soaked or impregnated with an aerosol-forming material, a substance is released from the substrate or from the web material, which may form an inhalable aerosol.

[0083] The continuous web material is preferably formed into an endless rod for future production of individual plugs. As the rod is formed, a susceptor may be inserted into the rod. For example, susceptor strips may be inserted into the continuous web material during assembly of the web material. This may produce an inductively heatable rod or plug.

[0084] The continuous web material is preferably pre-treated before being formed in an apparatus according to the present invention, for example by crimping or embossing or both.

[0085] The method preferably includes providing a crimped continuous web material having longitudinally disposed crimps. The crimps are disposed in the transport direction of the web material. As the continuous web material is assembled, it forms longitudinal channels along the crimps. The longitudinal channels define the pull resistance of an article formed by the assembly of the web material or an article comprising a plug of the assembly of the web material. Preventing fusion of such longitudinal channels due to melting of the web material during assembly allows for reproducibility of the pull resistance of the assembly of the web material to be achieved. Preventing fusion of the longitudinal channels is particularly advantageous when using web materials that are otherwise substantially gas impermeable.

[0086] The continuous web material used in the method according to the invention has a glass transition temperature of less than 150 degrees Celsius. The continuous web material preferably has a glass transition temperature of less than 100 degrees Celsius. Since the glass transition temperature is less than the melting temperature, the continuous web material also preferably has a melting temperature of around or below 150 degrees Celsius. Since the glass transition temperature refers to a range rather than an exact temperature, it is preferred to include plus or minus 20 degrees Celsius around the particular glass temperature, and more preferably to include plus or minus 5 degrees Celsius around the particular glass transition temperature.

[0087] The continuous web material preferably has a void volume of less than about 5 percent, and preferably less than about 2 percent. Most preferably, the continuous web material is gas impermeable, e.g., air impermeable.

[0088] The material used to form the continuous rod preferably has low or substantially no porosity.

[0089] Porosity is defined herein as a measure of the pores or openings that extend through a web material. For example, if a web material has openings or pores that total 50 percent of the web area, the porosity will be 50 percent. Similarly, if a web material is completely dense and has no pores that extend through the web, the web material has a porosity of 0 percent. Porosity may be measured or calculated using known methods.

[0090] For example, the rods may be made of a web material, such as a polymer web, or a polypropylene material, such as polyethylene (having a glass transition temperature of about -130 degrees Celsius to about -80 degrees Celsius, and a melting temperature of about 115 degrees Celsius to about 130 degrees Celsius), polypropylene (having a glass transition temperature of about -20 degrees Celsius to about 0 degrees Celsius, and a melting temperature of about 130 degrees Celsius to about 170 degrees Celsius), polyvinyl chloride (having a glass transition temperature of about 60 degrees Celsius to about 87 degrees Celsius, and a melting temperature of about 160 degrees Celsius to about 20 degrees Celsius), or a polypropylene material, such as polyvinyl chloride (having a glass transition temperature of about 60 degrees Celsius to about 87 degrees Celsius, and a melting temperature of about 160 degrees Celsius to about 20 degrees Celsius). 60 degrees Celsius), polyethylene terephthalate (having a glass transition temperature of about 70 degrees Celsius and a melting temperature less than about 250 degrees Celsius), polylactic acid (having a glass transition temperature of about 50 degrees Celsius to about 65 degrees Celsius and a melting temperature of about 155 degrees Celsius), cellulose acetate (having a glass transition temperature of about 100 degrees Celsius to about 130 degrees Celsius and a melting temperature of about 170 degrees Celsius to about 240 degrees Celsius).

[0091] The equipment and method according to the invention are particularly suitable for materials with low glass transition temperatures. The continuous web material formed in the equipment and according to the invention has a glass transition temperature of less than 150 degrees Celsius, for example less than 100 degrees Celsius. The continuous web material is preferably a plastic material, for example polylactic acid. The continuous material may be a crinkled continuous web material.

[0092] The invention will be further explained with respect to embodiments illustrated by the following drawings. [Brief description of the drawings]

[0093] [Figure 1]FIG. 1 is a schematic diagram of the funnel stage of the rod manufacturing process. [Diagram 2] Figure 2 shows the forming and cooling device. [Diagram 3] FIG. 3 shows the installation of FIG. 2 with a rod cooling device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0094] In the manufacturing process shown diagrammatically in Figure 1, and in the installation shown in Figure 2, a continuous web material 1, e.g. polylactic acid, is unwound from a storage bobbin (not shown). The web of polylactic acid is preferably transported through different processes (e.g., from a crimping process to a forming process in a forming apparatus 2) where the web material 1 is gathered and compressed into a continuous rod.

[0095] The web material 1 enters the semi-funnel interior of the upper forming element 20 in a process / conveying direction indicated by arrow 100 .

[0096] The rod forming is performed by an upper forming element 20 and a lower closing element 21. The upper forming element 20 is arranged on the opposite side of the closing element 21. The forming element 20 is a half funnel and forms the web material 1 from the top. The closing element 21 is a conveying plane with a groove, into which a wrapping material, for example a wrapping paper 5, is guided for wrapping the rod-shaped web material 1 along the web material. On the bottom of the forming device 2 and along the conveying plane, the web material 1 comes into contact with the wrapping paper 5, which moves along the conveying direction 100 at the same speed as the web material 1. The wrapping paper 5 is placed on a garniture tape 51 which pulls the wrapping paper 5. Thereby, the web material 1 is also pulled into and through the funnel of the forming device 2.

[0097] The grooves in the conveying plane of the closure element 21 typically take on a progressively concave shape, which supports the compression and shaping of the web material 1. Downstream of the former 2, the wrapping paper is folded and closed on itself to form a continuous cylindrically wound rod, preferably a polylactic acid rod wound in paper. The rod may then be cut into individual plugs, thereby producing components or segments used in the manufacturing process of the aerosol-generating article.

[0098] At conveying speeds of about 200 meters / min to about 500 meters / min, significant friction occurs between the web material 1 and the preferably metal, but stationary, forming device 2. In the areas where the web material is most compressed, it heats the most, as shown by line 200 in FIG.

[0099] 2, the web material is slightly gathered in the upstream funnel 22. The upstream funnel 22 is made of metal with a structured surface to reduce contact between the web material 1 and the surface of the upstream funnel 22.

[0100] The structure of the funnel surface is a dimple structure, the dimples being arranged laterally offset relative to one another when viewed along the transport direction of the web material, so that the web material 1 is in discontinuous contact with the wall of the upstream funnel 22 as it passes through the upper funnel 22.

[0101] In addition, the material of the upstream funnel 22 is an anti-friction material or is provided with an anti-friction coating.

[0102] To avoid friction-related overheating of the web material 1 above its glass transition temperature or above its melting temperature, the contact surface of the upper funnel portion 20 is cooled.

[0103] The contact surfaces are cooled to a temperature below 0 degrees Celsius by using a cooling fluid having a temperature below 0 degrees Celsius. For example, the cooling fluid as well as the contact surfaces of the half-funnel portion 20 have a temperature of approximately minus 5 degrees Celsius. The cooling fluid is preferably a mixture of 50 percent water and 50 percent glycol.

[0104] The cooling element 34 is disposed above the upper half funnel 20. The cooling element 34 is cooled by a cooling fluid circulating through a cooling fluid circuit in the cooling element 34. The cooling element 34 is in direct contact with the upper half funnel 20 and may be manufactured integrally with the upper half funnel 34. The cooling element 34 keeps the walls of the funnel at a temperature below 0 degrees Celsius. Due to the direct contact between the web material 1 and the walls of the funnel tube, the web material is cooled by the contact surface of the funnel tube wall. The cooling element is partially hollow, creating an internal reservoir of about 100 milliliters.

[0105] Cooling fluid is introduced into the upstream portion of the cooling element 34 by fluid inlet 23 and passes along the interior of the cooling element 34. The cooling fluid leaves the cooling element 34 at a fluid outlet 24 at the downstream end of the cooling element. The cooling element 34, through which the cooling fluid passes, is in thermal contact with the upper half-funnel 20 and the contact surface of the upper half-funnel. The upper half-funnel as well as the cooling element 34 are made of a thermally conductive material, for example a metal such as copper.

[0106] The closure element 21, in particular the conveying plane with the grooves, is preferably in thermal contact with the cooled upper half-funnel 20. Also through this thermal contact, the underside of the continuous web material 1 passing through the forming device 2 is indirectly cooled by the cooling element 34. The closure element 21 is preferably made of a thermally conductive material, for example a metal, to support the thermal transfer of cold from the cooling element 34 to the grooves in the conveying plane.

[0107] The contact surface has a concave shape that converges to the downstream end of the contact surface and the downstream end of the upper half funnel 20. Hence, the web material 1 is assembled and formed into a rod shape in the forming apparatus, whereby it is constantly cooled by the contact surface having a temperature below 0 degrees Celsius. Hence, the temperature of the web material is kept well below its melting temperature and well below its glass transition temperature.

[0108] The web material itself is preferably cooled to a temperature below 4 degrees Celsius. In the case of a web of polylactic acid, the temperature of the material is preferably maintained at a temperature below 30 degrees Celsius. This is preferably achieved by reducing the temperature of the cooling fluid in the reservoir of the cooling element 34 to approximately minus 5 degrees Celsius.

[0109] Examples of the length 37 over which the web material is cooled while in direct contact with the cooled contact surface of the forming device 2 are approximately 0.05 meters and 0.5 meters. This length preferably corresponds to the length of the upper half-funnel 20 of the forming element.

[0110] In FIG. 3, a portion of the forming apparatus 2 of FIG. 2 can be seen, as well as the wrapping section and rod cooling apparatus 6 arranged downstream.

[0111] The web material 1 formed into a rod in forming apparatus 2 is completely wrapped with wrapping paper in rod forming apparatus 50. In rod forming apparatus 50, the wrapping material 5 is provided with an adhesive seam and closed upon itself, thereby forming a wrapped rod of web material.

[0112] The rod cooling device 6 is arranged immediately downstream of the wrapping device. It comprises a longitudinal body 60 arranged above the conveying plane 11 and above the groove 12, in which the wound rod of web material is guided.

[0113] The body 60 of the rod cooling device 6 includes a cooling fluid inlet 63 at its upstream end and a cooling fluid outlet 64 at its downstream end. The cooling fluid is preferably the same as the cooling fluid used to cool the forming device 2. The cooling fluid for cooling the wound rod has a temperature below 0 degrees Celsius, for example about minus 5 degrees Celsius. The cooling fluid passes through the rod cooling device 6 and cools the rod cooling contact surface 61 of the rod cooling device 6 to a temperature below 0 degrees Celsius.

[0114] The rod contact surface extends along the body 60 and preferably has a concave shape to snugly contact a wound rod of web material passing beneath the rod contact surface 61 .

[0115] The rod cooling device 6, or at least the body 60 with the rod contact surface 61, is rotatable about the arm so as to be raised from the cooling position into the retracted position. In the cooling position, the rod cooling device 6 essentially forms a roof above the garniture tape 51 guided along the conveying plane 11. In Fig. 3 the rod cooling device 6 is shown in the retracted position. In the retracted position the rod cooling device 6 allows free access and visibility to the wrapping process and the rod cooling part of the manufacturing process.

Claims

1. 1. A method of forming a continuous web of material into a rod, comprising: providing a continuous web material having a glass transition temperature of less than 150 degrees Celsius; - gathering said continuous web material from a flat shape into a rod shape by a forming device; - providing cooling means for providing a temperature below 4 degrees Celsius and for cooling the material contacting surfaces of said forming device to a surface temperature below 4 degrees Celsius; - cooling the collection of continuous web material by the cooled material contact surface being in contact with the collection of continuous web material.

2. The method of claim 1, further comprising: - cooling the collection of continuous web material to a material temperature of less than 4 degrees Celsius.

3. 3. A method according to claim 1 or claim 2, wherein the cooling means is a cooling fluid.

4. A method according to any one of claims 1 to 3, wherein the cooling means provides a cooling temperature of between 3 degrees Celsius and minus 45 degrees Celsius.

5. The method of any one of claims 1 to 4, wherein the surface temperature of the material contact surface is between 3 degrees Celsius and minus 45 degrees Celsius.

6. The method of any one of claims 1 to 5, further comprising guiding a continuous strip of wrapping material along a conveying plane of the forming apparatus.

7. 7. The method of any one of claims 1 to 6, comprising a stepwise gathering of the continuous web material into the rod shape, in which in a first gathering step, the continuous web material is gathered from the flat shape into a rod shape having a first diameter, and in a second gathering step, the continuous web material is further gathered from the rod shape having the first diameter into a final rod shape having a final diameter smaller than the first diameter.

8. - wrapping said rod-shaped collection of continuous web material with a continuous strip of wrapping material provided with adhesive to form a wound rod of the collection of continuous web material; - cooling a rod contact surface of a rod cooling device using said cooling means to a rod contact surface temperature of less than 4 degrees Celsius and contacting said wound rod of said collection of continuous web material with said cooled rod contact surface; The method of any one of claims 1 to 7, further comprising cooling the wrapping material provided with adhesive and wound around the rod of a collection of continuous web material by the cooled rod contact surface in contact with the wound rod.

9. The method of any one of claims 1 to 8, wherein the continuous web material has a glass transition temperature of less than 100 degrees Celsius.

10. A method according to any one of the preceding claims, wherein the continuous web material is a plastic material, for example polylactic acid.

11. 1. An apparatus for forming a continuous web of material into a rod, comprising: a forming apparatus for forming the continuous web material from a flat shape into a rod shape, the forming apparatus including a funnel portion for forming the continuous web material into a rod shape; the forming apparatus including a material contact surface for contacting the continuous web of material guideable through the funnel portion; The facility, The system further comprises cooling means for providing a cooling temperature of less than 4 degrees Celsius, the forming apparatus being in communication with the cooling means and adapted to cool the material contact surface of the forming apparatus to a surface temperature of less than 4 degrees Celsius, the material contact surface being disposed along a length of the funnel portion of the forming apparatus to cool the continuous web material while it is being collected within the funnel portion.

12. a wrapping device for wrapping the rod-shaped web material with a continuous strip of wrapping material to form a wound rod of the continuous web material assembly; 12. The apparatus of claim 11, further comprising: a rod cooling apparatus having a rod contact surface for contacting the wrapped rod of web material, the rod cooling apparatus adapted to cool the rod contact surface of the wrapping apparatus to a rod contact surface temperature of less than 4 degrees Celsius, thereby cooling the wrapping material wrapped around the rod of web material.

13. The arrangement of claim 12 , wherein the material contact surface and the rod contact surface have a concave shape.

14. The installation according to any one of claims 11 to 13, wherein the funnel portion comprises an upper funnel section and a lower conveying plane with longitudinally extending converging grooves.

15. The apparatus of claim 14 , wherein the material contact surface extends from an upstream end of the upper funnel to a downstream end of the upper funnel.

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