METHOD AND APPARATUS FOR SHAPING A CONTINUOUS WEB MATERIAL INTO A ROD

Abstract

The method for shaping a continuous web material (1) into a rod comprises providing a continuous web material (1) having a glass transition temperature below 150 degree Celsius and gathering the continuous web material (1) from a flat shape into a rod-shape by means of a shaping device (2). The method further comprises providing a cooling means (34) providing a temperature below four degree Celsius, cooling a material contact surface of the shaping device (2) to a surface temperature below four degree Celsius, and cooling the continuous gathered web material by the cooled material contact surface in contact with the continuous gathered web material. Also provided is an apparatus for shaping a continuous web material (1).

Claims

1. A method for shaping a continuous web material into a rod, the method comprising: providing a continuous web material having a glass transition temperature below 150 degree Celsius; gathering the continuous web material from a flat shape into a rod-shape by means of a shaping device; providing a cooling means providing a temperature below four degree Celsius and cooling a material contact surface of the shaping device to a surface temperature below four degree Celsius; cooling the continuous gathered web material by the cooled material contact surface in contact with the continuous gathered web material.

2. The method according to claim 1, further comprising: cooling the continuous gathered web material to a material temperature of below four degree Celsius.

3. The method according to claim 1, wherein the cooling means is a cooling fluid, preferably a liquid, more preferably a mixture of water and glycol.

4. The method according to claim 1, wherein the cooling means provides a cooling temperature between three degree Celsius and minus 45 degree Celsius, preferably between three degree Celsius and minus 30 degree Celsius, more preferably between zero degree Celsius and minus 20 degree Celsius.

5. The method according to claim 1, wherein the surface temperature of the material contact surface is between three degree Celsius and minus 45 degree Celsius, preferably between three degree Celsius and minus 30 degree Celsius, more preferably between zero degree Celsius and minus 20 degree Celsius.

6. The method according to claim 1, further comprising guiding a continuous strip of wrapping material along a transport plane of the shaping device.

7. The method according to claim 1, comprising a step-wise gathering of the continuous web material into the rod shape, therein in a first gathering step gathering the continuous web material from the flat shape to a rod shape having a first diameter; and in a second gathering step further gathering the continuous web material from the rod shape having the first diameter to a final rod shape having a final diameter smaller than the first diameter.

8. The method according to claim 1, further comprising: material provided with adhesive; cooling a rod contact surface of a rod cooling device with the cooling means to a rod contact surface temperature below four degree Celsius and contacting the wrapped rod of continuous gathered web material with the cooled rod contact surface; thereby cooling the wrapping material provided with adhesive and wrapped around the rod of continuous gathered web material by the cooled rod contact surface in contact with the wrapped rod.

9. The method according to claim 1, wherein the continuous web material has a glass transition temperature below 100 degree Celsius.

10. The method according to claim 1, wherein the continuous web material is a plastic material, for example polylactic acid.

11. An apparatus for shaping a continuous web material into a rod, the apparatus comprising: a shaping device for shaping a continuous web material from a flat shape into a rod shape, the shaping device comprising a funnel portion for giving the continuous web material a rod shape, wherein the shaping device comprises a material contact surface for contacting the continuous web material guidable through the funnel portion; the apparatus further comprising cooling means for providing a cooling temperature below four degree Celsius, wherein the shaping device is in connection with the cooling means and is adapted for cooling the material contact surface of the shaping device to a surface temperature below four degree Celsius, wherein the material contact surface is arranged along the length of the funnel portion of the shaping device to cool the continuous web material while being gathered in the funnel portion.

12. The apparatus according to claim 11, further comprising: a wrapping device for wrapping the rod-shaped web material with a continuous strip of wrapping material; a rod cooling device comprising a rod contact surface for contacting the wrapped rod of web material, wherein the rod cooling device is adapted for cooling the rod contact surface of the wrapping device to a rod contact surface temperature below four degree Celsius, thereby cooling the wrapping material wrapped around the rod of web material to a wrapper temperature.

13. The apparatus according to claim 11, wherein the material contact surface and the rod contact surface have a concave shape.

14. The apparatus according to claim 11, wherein the funnel portion comprises an upper funnel part and a lower transport plane comprising a longitudinally extending converging groove.

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

Description

[0091] The invention is further described with regard to embodiments, which are illustrated by means of the following drawings, wherein:

[0092] FIG. 1: is a schematic drawing of a funnel stage of a rod manufacturing process;

[0093] FIG. 2: shows a shaping and cooling device;

[0094] FIG. 3: shows the apparatus of FIG. 2 with a rod cooling device.

[0095] In the manufacturing process schematically shown in FIG. 1 and in the apparatus shown in FIG. 2, a continuous web material 1, for example polylactic acid, is unwound from a storage bobbin (not shown). The web of polylactic acid is preferably conveyed through different processes, for example a crimping process up to a shaping process in the shaping device 2, where the web material 1 is gathered and compressed into a continuous rod.

[0096] The web material 1 enters inside the half-funnel of an upper shaping element 20 in the processing and transport direction indicated by arrow 100.

[0097] The rod-shaping is performed via the upper shaping element 20 and the lower closing element 21. The upper shaping element 20 is arranged opposite the closing element 21. The shaping element 20 is a half-funnel and shapes the web material 1 from the top. The closing element 21 is a transport plane comprising a groove, where a wrapping material, for example wrapping paper 5, is guided in the groove for wrapping the rod-shaped web material 1 along the web material. On the bottom of the shaping device 2, along the transport plane, the web material 1 comes in contact with the wrapping paper 5 also moving along transport direction 100 at the same speed as the web material 1. The wrapping paper 5 is put on a garniture tape 51 that pulls the wrapping paper 5. By this, also the web material 1 is pulled into and through the funnel of the shaping device 2.

[0098] The groove in the transport plane of the closing element 21 typically takes a progressive concave shape that supports compressing and shaping the web material 1. Downstream of the shaping device 2, the wrapping paper is folded and closed on itself, forming a continuous cylindrical wrapped rod, preferably a polylactic acid rod wrapped in paper. The rod may subsequently be cut into individual plugs thereby generating a component or segment used in the manufacturing process of an aerosol-generating article.

[0099] At a transport speed of between about 200 meters per minute and about 500 meters per minute, substantial friction between the web material 1 and the preferably metallic but stationary shaping device 2 occurs. In regions where the web material is most compressed the web material is heated up most. This is indicated in FIG. 1 by lines 200.

[0100] As shown in FIG. 2, the web material is slightly gathered in an upstream funnel 22. The upstream funnel 22 is made of a metal with structured surface to reduce the contact between the web material 1 and the surface of the upstream funnel 22.

[0101] The structure of the funnel surface is a dimple structure wherein dimples are arranged sideways displaced to each other when seen along a transport direction of the web material. By this, the web material 1 is in non-continuous contact with the wall of the upstream funnel 22 when passing the upper funnel 22.

[0102] In addition, the material of the upstream funnel 22 is an anti-friction material or provided with an anti-friction coating.

[0103] In order to avoid a 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.

[0104] The contact surface is cooled to a temperature below zero degree Celsius by using a cooling fluid having a temperature below zero degree Celsius. For example the cooling fluid as well as the contact surface of the half funnel portion 20 has a temperature of about minus five degree Celsius. Preferably, the cooling fluid is a mixture of 50 percent water and 50 percent glycol.

[0105] A cooling element 34 is arranged above the upper half funnel 20. The cooling element 34 is cooled via the 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 in one piece with the upper half funnel 34. The cooling element 34 keeps the wall of the funnel at a temperature below zero degree Celsius. Via direct contact of the web material 1 with the wall of the funnel, the web material is cooled via the contact surface of the funnel wall. The cooling element is partially hollow, creating an interior reservoir of about 100 millilitre.

[0106] The cooling fluid is introduced via a fluid inlet 23 into an upstream portion of the cooling element 34 and passes inside along the cooling element 34. The cooling fluid leaves the cooling element 34 at a fluid outlet 24 at a downstream end of the cooling element. The cooling element 34, where the cooling fluid passes through, is in thermal contact with the upper half funnel 20 and with the contact surface of the upper half funnel. The cooling element 34 as well as the upper half funnel is made of a thermally conductive material, for example metal such as copper.

[0107] Preferably, the closing element 21, in particular the transport plane comprising the groove is in thermal contact with the cooled upper half funnel 20. Through this thermal contact also a lower side of the continuous web material 1 passing the shaping device 2 is indirectly cooled by the cooling element 34. Preferably, the closing element 21 is made of a thermally conductive material such as for example metal, to support thermal transfer of cold from the cooling element 34 to the groove in the transport plane.

[0108] The contact surface has a concave shape converging versus the downstream end of the contact surface and of the upper half funnel 20. Thus, the web material 1 is gathered and formed to a rod shape in the shaping device, and is thereby constantly cooled by the contact surface having temperatures below zero degree Celsius. Thus the temperature of the web material is kept well below its melting temperature and well below its glass transition temperature.

[0109] Preferably, the web material itself is cooled down to temperatures below four degree Celsius. For a web of polylactic acid, the temperature of the material is preferably kept below 30 degrees Celsius. Preferably, this is achieved by lowering the temperature of the cooling fluid in the reservoir of the cooling element 34 to about minus 5 degrees Celsius.

[0110] Examples of a length 37 over which the web material is cooled while being in direct contact with the cooled contact surface of the shaping device 2 are about 0.05 meter and 0.5 meter. Preferably, this length corresponds to the length of the upper half funnel 20 of the shaping element.

[0111] In FIG. 3 a part of the shaping device 2 of FIG. 2 may be seen as well as the downstream arranged wrapping part and a rod cooling device 6.

[0112] A web material 1 shaped into a rod in the shaping device is completely wrapped with wrapping paper in the rod forming device 50. In the rod forming device 50, wrapping material 5 is provided with a seam of glue and closed on itself thereby forming a wrapped rod of web material.

[0113] The rod cooling device 6 is arranged immediately downstream of the wrapping device. The rod cooling device 6 comprises a longitudinal body 60 arranged above the transport plane 11 and above the groove 12 where the wrapped rod of web material is guided in.

[0114] The body 60 of the rod cooling device 6 comprises a cooling fluid inlet 63 at its upstream end and a cooling fluid outlet 64 at its downstream end. Preferably, the cooling fluid is the same as the cooling fluid used for cooling the shaping device 2. The cooling fluid for cooling the wrapped rod has a temperature below zero degree Celsius, for example about minus five degree 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 zero degree Celsius.

[0115] The rod contact surface extends along the body 60 and preferably has a concave shape such as to neatly contact a wrapped rod of web material passing underneath the rod contact surface 61.

[0116] The rod cooling device 6 or at least the body 60 with the rod contact surface 61 is rotatable around an arm such as to be lifted from a cooling position into a retracted position. In the cooling position, the rod cooling device 6 basically forms a roof over the garniture tape 51 guided along the transport 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 view onto a wrapping process and the rod cooling part of the manufacturing process.