The present invention relates to a glue application module for applying glue on a running band of wrapping material. The invention also relates to an apparatus for the production of rod shaped elements for aerosol-forming articles. The invention further relates to a method for the application of glue on a running band of wrapping material.

During the production of rod shaped elements for aerosol-forming articles a sheet-like material, the so called wrapping material, is wrapped around another material to form a rod shaped element. Before the wrapping step, glue has to be deposited onto a surface of a band of wrapping material which is running at high speed.

For example, in the method disclosed in patent document US 7,140,164 B2 the band of wrapping material runs along several guiding rolls and glue is applied by a nozzle which is located between the guiding rolls.

GB 1 238 845 A relates to the manufacture of continuous wrapped rods. In order to assist in applying the adhesive, the band of wrapping material is supported to have an appropriate tension and resilience. This is achieved by means acting on the band just upstream and just downstream of a zone in which the adhesive is applied.

Generally, the band of wrapping material levitates between the guiding rolls in order to minimize mechanical friction. However, the levitating band of wrapping material may fluctuate.

Thus, at the location of the nozzle there are fluctuations in the position of the band of wrapping material with respect to the nozzle. Accordingly, there may be variations in the glued area on the wrapping material. Due to the variations, the position and thickness of glue on the wrapping material varies and the gluing effect may not be sufficient and accurate. Inaccurate gluing can lead to instabilities of the rod, especially, when materials like poly lactic acid (PLA) which exhibit strong mechanical resistance to cutting and, optionally, which have poor gluing properties are glued to the wrapping material. Also, the seam line, which is the line where the wrapping material is glued onto itself in order to permanently close the rod, may be glued inaccurately.

Thus, it would be desirable to reduce the fluctuations in the positions of the band of wrapping material. Accordingly, a more accurate gluing would be achieved. It would further be desirable to have a glue application module which allows precise gluing even at high speed and which allows using different kinds of glue simultaneously.

According to a first aspect of the invention there is provided a glue application module for applying glue on a running band of wrapping material, preferably, for the production of rod shaped elements for aerosol-forming articles, comprising a glue emitting nozzle and a support element, wherein the glue emitting nozzle is located in close proximity to the support element. The support element supports the running band of wrapping material. Preferably, the support element is a paper guide, comprising a flat bottom part and a pair of side walls, or a positioning pin having an essentially cylindrical shape.

Thus, the running band of wrapping material is held in position by the support element. Accordingly, fluctuations of the band are reduced and the nozzle is prevented from getting either too far away from, or too close to, the surface of the running band of wrapping material. Thus, with the running band of wrapping material being held in position by the support element, glue may be applied more accurately onto the wrapping material.

The running band of wrapping material has two opposing surfaces which are each defined by the width of the band and, perpendicular to the width, by the length of the band along the processing direction. The processing direction is the direction along which the band is guided through the glue application module. The surface on which the glue is deposited by the glue emitting nozzle represents the inside surface of the wrapping material when the wrapping material is wrapped in order to form a rod shaped element.

Suitable wrapping materials include any type of flexible sheet-like materials known in the art for the production of rod shaped elements for aerosol-forming articles. Suitable materials include but are not limited to cellulose based papers, plastics, and cellophane.

A support element to be used with the glue application module of the invention is any component which is provided in close proximity to the nozzle and that, in use of the module, may support the running band of wrapping material. The support element may reduce fluctuations of the band of wrapping material at a location where said nozzle disposes glue on the wrapping material.

The term "in close proximity" is to be construed as relating to distances between the nozzle and the support element which are functionally limited by a maximum effective distance measured from the support element along a direction in parallel to the processing direction of the running band of wrapping material. The maximum effective distance corresponds to the distance above which the support element does no longer effectively support the running band of wrapping material. Thus, at distances exceeding the maximum effective distance fluctuations of the running band of wrapping material may not be effectively suppressed by the support element. The maximum effective distance may vary in dependence of, for example, the type and dimensions of the support element and the type and dimensions of the wrapping material used.

For the glue emitting nozzle to be located in close proximity to the support element the distance between the nozzle and the support element measured along a direction in parallel to the processing direction of the running band of wrapping material may be 50 millimeters or less, 25 millimeters or less, or 10 millimeters or less.

For the glue emitting nozzle to be located in close proximity to the support element the distance between the nozzle and the support element measured along a direction orthogonal to the longitudinal axis of the nozzle may be 50 millimeters or less, 25 millimeters or less, or 10 millimeters or less.

For the glue emitting nozzle to be located in close proximity to the support element the distance between the support element and the glue emitting nozzle may be between 1 and 100 millimeters, between 2 and 50 millimeters, or between 5 and 20 millimeters, or may be less than about 10 millimeters.

The ratio of the distance between the support element and the glue emitting nozzle to the width of the running band of wrapping material may be between 0.04 and 4, between 0.08 and 2, or between 0.2 and 0.8.

If the support element has a cylindrical shape, the ratio of the distance between the support element and the glue emitting nozzle to the radius of the support element may be between 0.25 and 25, between 0.5 and 12.5, or between 1 .25 and 5.

By choosing the distances in accordance to one of the above embodiments, the running band of wrapping material can be held in position by the support element and, thus, the wrapping material can be glued accurately.

The support element may comprise a sliding surface that, in use of the module, is in contact with the running band of wrapping material. The running band of wrapping material may be located in a plane defined by the sliding surface of the support element. The running band of wrapping material may be located in a plane defined by the sliding surfaces of a plurality of support elements. The sliding surface provides a physical barrier for the fluctuations of the running band of wrapping material. The sliding surface is aligned with the surface of the running band of wrapping material. Thus, the sliding surface allows the running band to slide over the sliding surface along the processing direction of the band whenever there is physical contact between the sliding surface and the band. The physical contact may be caused by the fluctuations of the band. The sliding surface is designed so as to provide only little mechanical friction between the sliding surface and the running band of wrapping material. Thus, the sliding surface is a smooth surface. Additionally, the sliding surface may comprise one or more low friction materials. Suitable materials include but are not limited to polytetrafluorethylene and polished metals.

The support element may comprise a sliding surface for the running band of wrapping material and the area of the sliding surface may be between 1 and 1250 square millimeters, between 5 and 200 square millimeters, or between 15 and 35 square millimeters. The sliding surface may also comprise one or more heat conductor metals or alloys like copper, aluminium, or steel. Heat conductor metals or alloys allow to effectively dissipate the heat which is generated by friction between the band and the sliding surface. Thus, unfavourably high temperatures which may damage the band can be avoided.

The surface of the running band of wrapping material may define a plane, wherein the glue emitting nozzle and the support element are provided at opposite sides of the plane. In use of the glue application module the running band of wrapping material may be guided between the glue emitting nozzle and the support element.

The exact position of the glue emitting nozzle may be adjustable in at least two dimensions so that, during operation, the exact position of the glue emitting nozzle is adjustable with respect to the processing direction and with respect to the perpendicular direction within the plane defined by the surface of the running band of wrapping material. In another embodiment, the exact position of the glue emitting nozzle is adjustable along three perpendicular directions with respect to the surface of the running band of wrapping material.

The support element may be a paper guide, comprising a flat bottom part and a pair of side walls. The side walls of the paper guide are located at opposite ends of the flat bottom part. The side walls are oriented essentially perpendicular to the flat bottom part. Accordingly, the flat bottom part together with the pair of side walls forms a u-shaped cross section.

The term "paper guide" is to be construed as relating to support elements which may be used with any type of wrapping material suitable for the invention.

The width of the flat bottom part of the paper guide may be equal to or greater than the width of the running band of wrapping material and, optionally, the length of the flat bottom part of the paper guide may be equal to or greater than the width of the running band of wrapping material. The width of the flat bottom part of the paper guide may be between 15 and 35 millimeters, or may be at least 25 millimeters. Alternatively or in addition, the length of the flat bottom part of the paper guide may be between 15 and 35 millimeters, or may be at least 25 millimeters.

The flat bottom part of the paper guide may comprise a sliding surface. The width of the sliding surface may be between 15 and 35 millimeters, or may be at least 25 millimeters. Alternatively or in addition, the length of the sliding surface may be between 15 and 35 millimeters, or may be at least 25 millimeters.

The side walls of the paper guide may represent guide rails for the running band of wrapping material in a direction perpendicular to the processing direction of the running band of wrapping material. Additionally, the paper guide may further comprise a top part for at least partly enclosing the running band of wrapping material. Optionally, the top part of the paper guide is a flat top part extending from each upper end of the side walls.

The support element may be a positioning pin having an essentially cylindrical shape, or having an entirely cylindrical shape. For example, the radius of the cylindrical pin may be between 2 and 6 millimeters, between 3 and 5 millimeters, or may be about 4 millimeters. The cylindrical shape of the positioning pin may define a smooth sliding surface with a small area. Smooth and small area sliding surfaces are advantageous because they provide only little mechanical friction between the sliding surface and the running band of wrapping material.

Preferably, the longitudinal axis of the positioning pin is oriented parallel to the plane defined by the running band of wrapping material and perpendicular to the processing direction of the running band of wrapping material. Thus, only the small part of the cylindrical surface of the positioning pin which faces the surface of the band of wrapping material serves as a sliding surface. Due to the small area of the sliding surface, there is only little friction between the positioning pin and the band of wrapping material.

The longitudinal axis of the positioning pin may extend over the whole width of the running band of wrapping material. Thus, the positioning pin may stabilize the band over the whole width of the band which may provide a particularly good stabilization of the band.

The external surface of the positioning pin may be very smooth in order to reduce friction with the wrapping material. However, during use of the glue application module, small amounts of the glue which is emitted by the nozzle may accumulate on the positioning pin so as to form glue spots. Such glue spots, when dried, could increase friction with the band of wrapping material. Accordingly, the positioning pin may be removably fixed to the glue application module. Thus, the pin can be removed and a clean pin can be inserted. For example, the cylindrical positioning pin may be inserted into a hole in a block attached to the module, and the pin may be reversibly fixed to the block by means of a locking screw.

Additionally, the friction between the band and the positioning pin may mechanically drag the pin towards the processing direction. This may lead to a dislocation of the tip of the pin and, thus, may lead to a decrease in the stability of the position of the wrapping material. Glue application could be misplaced due to such dislocations. In order to reduce such dislocations, the pin may be additionally fixed by means of an extra anchoring part which may extends the hole in the block into which the pin is inserted. The extra anchoring part may be a separate element which is located on top of the block or the block and the extra anchoring part may form one extended block.

The length of the portion of the positioning pin that is inserted into the hole of the block may range between 10 to 40 percent and between 15 and 30 percent of the overall length of the positioning pin. If the block of the glue application module has a width that does not allow for inserting the positioning pin according to the above ratio, the extra anchoring part may be provided to effectively increase the depth of the hole. In this way it may be ensured that the positioning pin is stably anchored and that the friction is not dislocating the tip of the pin towards the processing direction.

The positioning pin may be statically mounted in the glue application module. Thus, the positioning pin does not comprise any rotatable parts. By this way, the positioning pin has a simple and durable construction.

The positioning pin may be rotatably mounted in the glue application module. Thus, the positioning pin can rotate about its longitudinal axis. By this way the friction between the positioning pin and the running band of wrapping material may be further reduced.

The positioning pin differs from conventional guiding rolls. Guiding rolls are known in the art. Guiding rolls are used to deflect the running band of wrapping material around a corner. Thus, conventional guiding rolls substantially change the orientation of the processing direction of the running band of wrapping material. In contrast, the positioning pin solely serves as a support for the running band of wrapping material. Therefore, the orientation of the processing direction of the running band of wrapping material is not substantially affected by the presence of the positioning pin.

Similarly, the paper guide serves as a support for the running band of wrapping material and the orientation of the processing direction of the running band of wrapping material is not substantially affected by the presence of the paper guide.

The glue application module of the invention may comprise a first glue emitting nozzle and two positioning pins being each located being each located in close proximity to first glue emitting nozzle and, optionally, a second glue emitting nozzle and a paper guide being located in close proximity to the second glue emitting nozzle.

The glue application module of the invention may comprise a plurality of positioning pins, one or more paper guides and one or more glue emitting nozzles. If the glue application module comprises at least two glue emitting nozzles, the average distance between two nozzles may be between 45 and 85 millimeters, between 55 and 75 millimeters, or may be about 65 millimeters.

All nozzles may be perpendicular to and may point toward the side of the surface of the running band of wrapping material which will be the inside surface when the wrapping material is wrapped to form a rod shaped element. Each nozzle may be activated to emit glue independently. The emitted glue may be hot melt glue or cold glue as required according to the specificity and characteristics of the wrapping material and those materials that will be wrapped in the rod shaped elements. The nozzle may be a glue gun using air to spray cold glue. The cold glue is coming from a hose connected to the nozzle and the spraying is done with compressed air coming from another hose connected to the same nozzle.

The exact position of each support element may be independently adjustable with respect to the remaining parts of the glue application module.

By adjusting the position of the support element the distance between the band of wrapping material and the glue emitting nozzle may be adjusted.

By adjusting the position of the paper guide the position of the band of wrapping material may be additionally adjusted in a direction within the plane defined by the running band of wrapping material and perpendicular to the processing direction of the running band of wrapping material.

Each of the one or more glue emitting nozzles and the one or more support elements may be embarked onto a movable common plate in order to allow movement of the glue application module according to three perpendicular directions. Adjusting the position of the module allows putting the module in a location where the overall fluctuations of the running band of wrapping material are low and where the components of the module are in a correct position reported to the wrapping material.

The glue application module of the invention may be adapted for applying glue on a running band of wrapping material which is between 15 and 35 millimeters in width, or which is about 25 millimeters in width. The glue application module of the invention may be further adapted for applying glue on a running band of wrapping material at a running speed of between 250 and 1000 meters per minute, between 250 and 600 meters per minute, or between 250 and 500 meters per minute. The glue application module of the invention may be further adapted for applying glue in an amount of 0.1 gram to 15 grams, or between 1 gram to 50 grams, per 500 meters of running band of wrapping material in a linear application of a thickness of 40 to 60 micrometers or about 50 micrometers, and a width of 0.8 millimeters to 2.5 millimeters. In another aspect, the invention relates to an apparatus for the production of rod shaped elements for aerosol-forming articles comprising the glue application module of the invention and a rod forming unit. The apparatus for the production of rod shaped elements for aerosol-forming articles may further comprise a feed unit for feeding a running band of wrapping material to the glue application module.

In another aspect, the invention relates to a method for the application of glue on a running band of wrapping material, preferably, for the production of rod shaped elements for aerosol-forming articles, comprising steps of providing a running band of wrapping material, providing a support element and a glue emitting nozzle in close proximity to each other, and depositing a line of glue on a surface of the wrapping material by the glue emitting nozzle. Preferably, the support element is a paper guide or a positioning pin. The paper guide comprises a flat bottom part, a pair of side walls which represent guide rails for the running band of wrapping material in a direction perpendicular to the processing direction of the running band of wrapping material, and, optionally, a top part for at least partly enclosing the running band of wrapping material. The positioning pin has an essentially cylindrical shape, wherein the longitudinal axis of the positioning pin is oriented parallel to the plane defined by the running band of wrapping material and perpendicular to the processing direction of the running band of wrapping material.

The method may comprise providing a glue emitting nozzle and two positioning pins which are located in close proximity to the glue emitting nozzle, wherein one of the positioning pins is located upstream of the glue emitting nozzle and the other positioning pin is located downstream of the glue emitting nozzle with respect to the processing direction of the running band of wrapping material. In such configuration, the distance between the two positioning pins may be between 10 and 30 millimeters, or between 15 and 25 millimeters, or may be about 20 millimeters with respect to their longitudinal central axes.

The method may comprise providing a first glue emitting nozzle and two positioning pins being each located in close proximity to the first glue emitting nozzle, wherein one of the positioning pins is located upstream of the first glue emitting nozzle and the other positioning pin is located downstream of the first glue emitting nozzle with respect to the processing direction of the running band of wrapping material and, optionally, providing a second glue emitting nozzle and a paper guide being located in close proximity to the second glue emitting nozzle.

The method may comprise providing at least two glue emitting nozzles for applying at least two lines of glue at different positions on the running band of wrapping material.

The invention also relates to a method for the production of rod shaped elements for aerosol-forming articles comprising steps of providing a running band of wrapping material, guiding the running band of wrapping material along one or more guiding rolls, providing a support element and a glue emitting nozzle in close proximity to each other, depositing a line of glue on an inside surface of the wrapping material by the glue emitting nozzle, placing one or more materials onto the inside surface of the wrapping material, wrapping the wrapping material around the one or more materials so as to form a continuous tubular rod, and cutting the rod into pieces to form individual rod shaped elements for aerosol-forming articles.

In another aspect of the invention there is provided a use of a glue application module of the invention for the production of rod shaped elements for aerosol-forming articles, comprising a material which provides a relative strong mechanical resistance such as poly lactic acid (PLA). Features described in relation to one aspect may equally be applied to other aspects of the invention.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 shows an arrangement of a glue emitting nozzle in front of a band of wrapping material;

Figs. 2A, 2B, and 2C illustrate the effects of the support elements on the fluctuations of a band of wrapping material;

Fig. 3 shows an embodiment of a paper to be used with the glue application module in accordance to the invention;

Fig. 4 shows an embodiment of a glue application module in accordance to the invention.

Fig. 5 shows an arrangement of two positioning pins with respect to a band of wrapping material.

Fig. 1 shows an embodiment of a glue emitting nozzle as being part of the glue application module 10 of the invention for applying glue 12 on a running band of wrapping material 14. The glue emitting nozzle 16 is oriented perpendicular to a surface of the running band of wrapping material 14. The surface facing the tip of the nozzle 16 defines the inside surface, when a rod shaped element for aerosol-forming articles is formed. Before depositing glue on the band 14, the exact position of the nozzle 16 could be adjusted along the processing direction of the running band 14. The processing direction is indicated by an arrow. Furthermore, the position of the nozzle 16 could also be adjusted "vertically", meaning along an axis perpendicular to the running band 14, and so along the width of the running band 14. The vertical adjustment direction along the width of the band 14 is indicated by two double arrows with dotted lines.

Figs. 2A, 2B, and 2C illustrate the effect of the support elements on the fluctuations of the running band of wrapping material 14. Each of Figs. 2A, 2B, and 2C shows a side view of a glue application module 10 in use, comprising a running band 14 which is running in a direction marked by an arrow along a path defined by two guiding rolls 18. In between the guiding rolls 18 there is provided a glue emitting nozzle 16.

Fig. 2A shows an embodiment of a glue application module 10 in accordance to the prior art, wherein no support element is provided. Fluctuations of the band of wrapping material are indicated by two dotted lines.

Fig. 2B shows an embodiment of a glue application module 10 in accordance to the invention, wherein one positioning pin 20 is provided in close proximity to the nozzle 16. The positioning pin 20 has an essentially cylindrical shape and the longitudinal axis of the positioning pin is oriented parallel to a plane defined by the surface of the running band of wrapping material 14 and perpendicular to the processing direction of the running band of wrapping material 14. In the figure, only the round end face of the cylindrical pin 20 is depicted. The glue emitting nozzle 16 and the positioning pin 20 are provided at opposite sides of the plane defined by the surface of the running band. The running band of wrapping material is guided between the glue emitting nozzle 16 and the positioning pin 20.

Thus, the positioning pin 20 acts as a support element and there are only little fluctuations of the band as indicated by a dotted line.

Finally, Fig. 2C shows an embodiment of a glue application module 10 in accordance to the invention, wherein two positioning pins 20 are provided in close proximity to the nozzle 16. One of the positioning pins 20 is located upstream of the glue emitting nozzle 16 and the other positioning pin 20 is located downstream of the glue emitting nozzle 16 with respect to the processing direction of the running band of wrapping material 14. In this embodiment there are even less fluctuations when compared to the embodiment with only one positioning pin as indicated by the dotted line.

Having two positioning pins 20 in close proximity to the glue emitting nozzle 16, wherein one pin is located upstream and the other one downstream of the nozzle enable to fine tune between a good stabilization of the position of the band of wrapping material 14 in front of the nozzle 16 and low friction on the wrapping material 14. The closer the pins 20 are to each other and to the nozzle 16, the less room is left for the fluctuations of the wrapping material 14 and, accordingly, the more the position of the wrapping material is stabilized and the more friction there is on the wrapping material. Accordingly, the glue application module can be precisely adapted to the requirements of the manufacturing products.

Fig. 3 shows an embodiment of a paper guide 22 to be used with the glue application module in accordance to the invention. The paper guide 22 comprises a flat bottom part 24 and a pair of side walls 26. In use, the flat bottom part 24 is aligned to the surface of the running band of wrapping material 14. The flat bottom part 24 and the glue emitting nozzle 16 are provided at opposite sides of the plane defined by the surface of the running band 14. The flat bottom part 24 of the paper guide 22 comprises a sliding surface for the band of wrapping material 14. Accordingly, the width of the sliding surface of the flat bottom part 24 should be at minimum equal to the width of the running band of wrapping material 14. The side walls 26 of the paper guide 22 represent guide rails for the running band of wrapping material 14 in a direction perpendicular to the processing direction of the running band of wrapping material 14.

Additionally, the paper guide 22 comprises a flat top part 28 extending from each upper end of the side walls 26 for partly enclosing the running band of wrapping material 14. Thus, the position of the running band of wrapping material is adjustable along an axis perpendicular to the surface of the band 14.

Further, the position of the paper guide 22 can be adjusted along 3 perpendicular axes with respect to the remaining parts of the glue application module 10. Moving the paper guide 22 will move the trajectory of the running band of wrapping material 14 and, hence, enables to fine tune the position of the band 14 according to the nozzle 16.

In order to limit the area of the sliding surface between the paper guide 22 and the band 14 so as to avoid damage and weakening of the wrapping material 14 due to friction, the paper guide 22 occupies only a small part of the path of the wrapping material 14 into the module 10.

Fig. 4 shows an embodiment of a glue application module 10 in accordance to the invention. Shown is a band of wrapping material 14 which is running in a direction marked by three arrows along a path defined by three guiding rolls 18. In between two of the guiding rolls 18 there is provided the glue application module 10. The module comprises a base of the module 30 and a handle 32 for adjusting the position of the module according to three perpendicular directions. The module further comprise two external glue emitting nozzles 16, and one central glue emitting nozzle 16 with respect to the processing direction of the band 14.

The three nozzles spray cold glue, two of them to bind materials such as poly lactic acid (PLA) to the inside surface of the wrapping material, and one to reinforce the seam glue line. The seam glue line may afterwards be glued a second time with hot melt glue downstream of the module 10 and just before the closing of the wrapping material 14 to form a rod shaped element. Having two lines of glue to bind materials to be wrapped to the inside surface of the wrapping material 14 may be especially useful for poly lactic acid (PLA) based materials which exhibit strong mechanical resistance to cutting. When cutting a continuous rod containing such material into small sticks, the material needs to be very strongly glued to the inside surface of the wrapping material in order to remain at a correct position in the wrapping material.

Each of the nozzles 16 shown in Fig. 4 is connected to hoses 34, 36 which provide air and glue to the nozzles. In close proximity to each of the two external nozzles there are provided two positioning pins 20, one upstream pin and one downstream pin, in similarity to the embodiment of Fig. 2C.

In proximity to the central nozzle 16 and above the base of the module 30 there is provided a paper guide 22. The upstream end of the paper guide 22 is located in close proximity to the nozzle 16. Fig. 5 shows an arrangement of two positioning pins 20 with respect to a band of wrapping material 14 as being part of the glue application module 10 of the invention in use. Two positioning pins 20 are located in close proximity to a nozzle (not shown) in an upstream and downstream arrangement as discussed before. The processing direction of the running band of wrapping material 14 is indicated by an arrow. Sizes and distances are given in millimeters and are indicated by double arrows.

The band of wrapping material 14 is about 25 millimeters in width and runs at running speeds of between 250 and 500 meters per minute. The band 14 runs at a distance of about 20 millimeters from the block 38 and extra anchoring part 40 into which the positioning pins 20 are inserted. 26 millimeters in length of each positioning pin 20 is inserted into the block 38 and the extra anchoring part 40. Thus, it is assured that the positioning pins 20 are stable and that the friction with the running band of wrapping material 14 is not dislocating the tip of the pin towards the processing direction.

The distance between the couple of positioning pins 20 is about 20 millimeters from axis to axis.

The exemplary embodiments described above illustrate but are not limiting. In view of the above discussed exemplary embodiments, other embodiments consistent with the above exemplary embodiments will now be apparent to one of ordinary skill in the art.