EP1911362A1

EP1911362A1 - Appartus for blooming cigarette filter tow band

Info

Publication number: EP1911362A1
Application number: EP06405415A
Authority: EP
Inventors: Leonid Biryukov
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2006-09-29
Filing date: 2006-09-29
Publication date: 2008-04-16

Abstract

An apparatus for blooming cigarette filter tow band (1) comprises a first pair (10, 11) and a second pair (20, 21) of rotatably arranged rollers. The second pair of rollers (20, 21) is arranged downstream of the first pair of rollers (10, 11) with respect to the direction of transport of the filter tow band (1) and is rotatable at a driving speed which is higher than the driving speed of the first pair of rollers (10, 11) so as to cause stretching of the filter tow band (1). Stretching of the filter tow band (1) is released once the filter tow band has passed through the second pair of rollers (20, 21) allowing blooming of the filter tow band to occur. A diverter (4) is adjacently arranged downstream the second pair of rollers (20, 21).

Description

The present invention relates to an apparatus for blooming cigarette filter tow band.
In the manufacture of cigarette filter tow, the filter tow is bloomed to expand the volume of the filter tow material. In a blooming apparatus filter tow band, e.g. made of acetate tow, is drawn from a bale and is then directed to an arrangement of three pairs of rollers. The second pair of rollers is arranged downstream of the first pair of rollers and the third pair of rollers is arranged downstream the second pair of rollers regarding the direction of transport of the filter tow band. The filter tow band is clamped between the roller pairs which are rotatably driven. The filter tow band is accelerated by the second pair of rollers. As a consequence, the filter tow band is stretched during its transport from the first pair of rollers to the second pair of rollers. Between the second pair of rollers and the third pair of rollers, the stretched filter tow band is decelerated. This releases the stretched filter tow band. As a consequence of the stretching process and the subsequent release of stretching the filter tow fibres become bloomed and the volume of the filter tow band increases The bloomed filter tow band is then further processed to form filter rods that are cut to a suitable length for further processing. The more the filter tow band is bloomed, that is, the higher the increase in volume of the filter tow band, the less filter tow band material is needed per filter volume. At the same time the so-called "resistance to draw" (resistance to draw air through the filter tow material) essentially does not change. It is therefore desirable to maximise the volume increase of the filter tow band by blooming all of the filter tow fibres.
As described, once the filter tow band has passed through the second pair of rollers, the stretched filter tow band is released and the volume of the filter tow band increases. However, due to the release of the stretching, the filter tow band tends to form a wave crest directly after the second pair of rollers. As a consequence, from time to time the filter tow may wind itself back around the second pair of rollers, in particular around the upper roller of the second pair of rollers. This may lead to jamming of the second pair of rollers, which causes the production of the filter tow band to stop and the jam to be cleared. This negatively affects the efficiency of the filter tow band production process. Also, jamming of the rollers may result in that the rollers must be changed more frequently than without jamming. Besides, the filter tow band that may have wound back around the upper roller cannot be used any more for cigarette filters.
The present invention now suggests an apparatus for blooming cigarette filter tow band, comprising a first pair, a second pair and a third pair of rotatably arranged rollers for clamping the filter tow band between the respective pairs of rollers and for transporting the filter tow band through rotatably driving the first, second and third pairs of rollers. The second pair of rollers is arranged downstream the first pair of rollers with respect to the direction of transport of the filter tow band and the third pair of rollers is arranged downstream the second pair of rollers. The first pair of rollers advances the filter tow band at a first driving speed. The second pair of rollers advances the filter tow band at a second driving speed. The third pair of rollers advances the filter tow band at a third driving speed. The second driving speed is higher than the first driving speed so as to cause stretching of the filter tow band during its transport from the first pair of rollers to the second pair of rollers. The third driving speed is lower than the second driving speed in order to release stretching of the filter tow band once it has passed through the second pair of rollers. A diverter is adjacently arranged downstream the second pair of rollers.
Throughout the document the term "driving speed" is used to indicate the speed of the filter tow band in the nip between a pair of rollers.
The diverter prevents formation of a wave crest directly behind the second pair of rollers and thus prevents filter tow band that has passed through the second pair of rollers from winding back around the second pair of rollers. Accordingly, the second driving speed may be increased which increases the stretching of the filter tow band between the first and second pair of rollers, if the first driving speed is maintained. At the same time the ratio of the second driving speed to the third driving speed is increased if the third driving speed is maintained. Especially, this ratio may be raised to exceed 1.3 . This increases the volume gain of the filter tow band during the releasing of the filter tow band. This reduces the required amount of filter tow band for a given volume and thus raises the efficiency of the process while the resistance to draw may remain at least essentially unchanged. Alternatively or in combination therewith the entire process speed may be raised by an increase of all the driving speeds.
Additionally, jamming of the second pair of rollers is prevented or at least substantially reduced even at higher speeds, thus increasing the efficiency of the process of producing filter tow band, since no or at least less stops of production are necessary. Also, less filter tow band is lost due to no or fewer jamming. The edge life of the rollers is increased, that is to say the rollers must be changed less frequently.
In one embodiment of the apparatus according to the invention, the first and second pairs of rollers are arranged such that each pair of rollers has an upper roller and a lower roller. The diverter has a guiding surface for holding down the filter tow band that has passed through the second pair of rollers. While not mandatory, the process of stretching and subsequent release of the filter tow band is performed essentially in a horizontal direction, so that without the diverter the upwardly directed wave crest may form (see above). The guiding surface of the diverter holds down the filter tow band and thus prevents formation of the wave peak or at least prevent formation of the wave peak directly after the rollers and thus prevents that filter tow band may wind back around the second pair of rollers and thus prevents jamming of the rollers.
In a further embodiment of the apparatus according to the invention, the upper roller of the second pair of rollers is arranged within a housing that is open at its base, and the diverter has a mounting portion which is mounted to the housing for the upper roller such that the filter tow band that has passed through the second pair of rollers is guided below the guiding surface of the diverter. This is an embodiment which is comparatively simple from a constructional point of view.
In still a further embodiment of the apparatus according to the invention, the diverter comprises an essentially V-shaped portion with the mounting portion of the diverter being formed at one end of the V-shaped portion and with an outlet mouth portion being formed at the other end of the V-shaped portion. Having this shape, the mounting portion of the diverter can be easily mounted to the housing while the outlet mouth portion allows the filter tow band to easily exit the space under the guiding surface of the diverter.
According to a further aspect of the apparatus according to invention, all angles included between the various portions of the diverter are about 30 degrees or multiples thereof. This simplifies manufacture of the diverter, since the diverter may be made from one single piece and the various portions of the diverter may be formed through bending of the single piece, with each bending step always including angles which are 30 degrees or multiples thereof, so that no complicated changeover of the bending machine must be performed during manufacture of the diverter.
Further advantageous aspects of the apparatus according to the invention may become apparent from the following description of an embodiment of the apparatus with the aid of the drawings in which:

Fig. 1: shows a schematic representation of essential parts of a prior art apparatus for blooming filter tow band,
Fig. 2: shows a schematic representation of essential parts of an embodiment of the apparatus according to the invention, and
Fig. 3: shows a side view of an embodiment of the diverter of the apparatus according to Fig. 2, and
Fig. 4: shows a sectional view of the embodiment of the diverter shown in Fig. 3, mounted to a housing for the upper roller of the second roller pair.

In Fig. 1 a schematic representation of a prior art apparatus for blooming filter tow band is shown. The filter tow band 1 is drawn from a bale (not shown) and passes through a first pair of rollers comprising upper roller 11 and lower roller 10. The filter tow band 1 then passes through a second pair of rollers comprising upper roller 21 and lower roller 20 and a third pair of rollers comprising upper roller 31 and lower roller 20. The filter tow band 1 is clamped between the upper rollers 11, 21, 31 and the lower rollers 10, 20, 30 of the roller pairs, respectively. The first pair of rollers 10, 11 advances the filter tow band 1 at a first driving speed V1. The second pair of rollers 20, 21 advances the filter tow band at a second driving speed V2. The third pair of rollers 30, 31 advances the filter tow band at a third driving speed V3. The direction of rotation of the rollers 10, 11, 20, 21, 30, 31, is indicated by arrows 100, 110, 200, 210, 300, 310, respectively.
The second driving speed V2 is higher than the first driving speed V1. As a consequence the filter tow band 1 is stretched during its transport from the first pair of rollers 10, 11 to the second pair of rollers 20, 21. The third driving speed V3 is lower than the second driving speed V2. Therefore, the stretched filter tow band 1 is released after it passes through the second pair of rollers 20, 21. Due to the release of the stretching, the filter tow fibres are bloomed and the filter tow band 1 increases in volume. The bloomed filter tow band 1 is further transported by the third pair of rollers 30, 31. The direction of transport of the filter tow band 1 is indicated by the arrows 2.
As can be seen in Fig. 1, due to the release of the stretching of the filter tow band 1 once it has passed through the second pair of rollers a wave crest 3 forms which may lead to the jamming of the rollers 20, 21 of the second pair of rollers, as this has been described above. According to the state of the art this wave crest 3 is especially likely to form for a driving speed ratio V2/V3 of the second driving speed V2 to the third driving speed V3 above 1.3 .
Fig. 2 shows a schematic representation of essential parts of an embodiment of the apparatus according to the invention, with like parts of the apparatus of the invention shown in Fig. 2 being assigned like reference signs as in the prior art apparatus shown in Fig. 1. According to a preferred embodiment of the invention a diverter 4 is arranged adjacently downstream of the second pair of rollers 20, 21 in the immediate vicinity of the second pair of rollers 20, 21. The formation of the wave crest 3 (see Fig. 1) is prevented by the diverter 4 which holds the stretched filter tow band 1 down, especially for a driving speed ratio V2/V3 of the second driving speed V2 to the third driving speed V3 above 1.3. Thus, jamming of the second pair of rollers 20, 21 is prevented even at a higher second driving speed.
While it is generally possible that both rollers of a pair of rollers are driven, usually only one roller of a pair of rollers is driven and the other roller of that pair of rollers is biased, e.g. spring-biased, against the driven roller. For example, the lower roller 10 of the first pair of rollers may be connected to a drive (not shown) while the upper roller 11 may be spring-biased against the lower roller 10. The same may hold for the second pair of rollers 20, 21 and for the third pair of rollers 30, 31.
As already mentioned, the second driving speed V2 of the second pair of rollers 20, 21 is higher than the first driving speed V1 of the first pair of rollers 10, 11 so as to cause the filter tow band 1 to be stretched during its transport between the first and second pair of rollers. Both the absolute driving speed of the first and second pairs of rollers 10, 11, 20, 21 as well as the driving speed ratio V1/V2 of the first driving speed V1 of the first pair of rollers 10, 11 to the second driving speed V2 of the second pair of rollers 20, 21 usually depend on the material of the filter tow used and may additionally depend on other production parameters. Also the driving speed ratio V2/V3 of the second driving speed V2 of the second pair of rollers 20, 21 to the third driving speed V3 of the third pair of rollers 30, 31 usually depend on the material of the filter tow used and may additionally depend on other production parameters. A commonly used filter tow band material is acetate.
The driving speed ratio V2/V3 of the second driving speed V2 and the third driving speed V3 is between 1.3 and 2, preferably between 1.4 and 1.9, more preferably between 1.5 and 1.8, and even more preferably between 1.6 and 1.7 . As mentioned before, this allows to optimize stretching of the filter tow band 1 between the first pair or rollers 10, 11 and the second pair of rollers 20, 21 and to maximize relaxation of the stretched filter tow band 1 once it has passed through the second pair of rollers 20, 21, while at the same time formation of the wave crest and jamming of the rollers are prevented.
Fig. 3 shows a side view of an embodiment of the diverter 4 of the apparatus shown in Fig. 2. The diverter 4 is made from a single piece and comprises a V-shaped portion 40, at one end of which a mounting portion 41 is formed. At the other end of the V-shaped portion 40, an outlet mouth portion 42 is provided. The outer surface 401 of one leg 400 of the V-shaped portion 40 defines a guiding surface 401 for holding down the stretched filter tow band 1 as it has passed through the second pair of rollers. The mounting portion 41 of the diverter 4 may be mounted to a housing 5 in which the upper roller 21 of the second pair of rollers may be mounted, as this is shown in Fig. 4. The housing has an open base, and the mounting portion 41 of the diverter 4 may be mounted, for example with the aid of screws and nuts, to the trailing side wall 50 (with regard to the direction of transport of the filter tow band) of the said housing 5. The V-shaped portion 40 of the diverter is then arranged such that as the stretched filter tow band 1 has passed through the second pair of rollers 20, 21 and relaxes, the stretched filter tow band 1 is immediately held down and is guided below the guiding surface 401 of the diverter 4 so as to prevent formation of the wave crest.
As can also be seen from Fig. 3, the angle 43 between the outlet mouth portion 42 and the leg 400 of the V-shaped portion may be about 150 degrees, while the angle 44 between the legs of the V-shaped portion 40 may be about 30 degrees, and the angle 45 between the mounting portion 41 and the other leg of the V-shaped portion 40 may be about 120 degrees. All the angles 43, 44, 45 are multiples of 30 degrees, which simplifies manufacture of the diverter 4 from one piece with a bending machine, which is adapted to always perform bending steps of 30 degrees so that the various portions of the diverter 4 may be formed by bending with no changeover of the bending machine being necessary during manufacture of the diverter 4.

Claims

Apparatus for blooming cigarette filter tow band (1), comprising a first pair (10, 11), a second pair (20, 21) and a third pair (30, 31) of rotatably arranged rollers for clamping the filter tow band (1) between the respective pairs of rollers and for transporting the filter tow band (1) through rotatably driving the first, second and third pairs of rollers (10, 11, 20, 21, 30, 31), the second pair of rollers (20, 21) being arranged downstream of the first pair of rollers (10, 11) and the third pair of rollers (30, 31) being arranged downstream of the second pair of rollers (20, 21) with respect to the direction of transport of the filter tow band (1), wherein the first pair of rollers (10, 11) is advancing the filter tow band (1) at a first driving speed (V1), wherein the second pair of rollers (10, 11) is advancing the filter tow band (1) at a second driving speed (V2), and wherein the third pair of rollers (10, 11) is advancing the filter tow band (1) at a third driving speed (V3), and wherein further the second driving speed (V2) is higher than the first driving speed (V1) so as to cause stretching of the filter tow band (1) during its transport from the first pair of rollers (10, 11) to the second pair of rollers (20, 21) and wherein the second driving speed (V2) is higher than the third driving speed (V3) to release stretching of the filter tow band (1) once it has passed through the second pair of rollers (20, 21), and wherein a diverter (4) is adjacently arranged downstream the second pair of rollers (20, 21).
Apparatus according to claim 1, wherein the diverter (4) has a guiding surface (401) for holding down the filter tow band (1) that has passed through the second pair of rollers (20, 21).
Apparatus according to claim 2, wherein the first (10, 11) and second pairs (20, 21) of rollers are arranged such that each pair of rollers has an upper roller (11;21) and a lower roller (10;20), and wherein the upper roller (21) of the second pair of rollers (20, 21) is arranged within a housing (5) that is open at its base, and wherein the diverter (4) has a mounting portion (41) which is mounted to the housing (5, 50) for the upper roller (21) such that the filter tow band (1) that has passed through the second pair of rollers (20, 21) is guided below the guiding surface (401) of the diverter (4).
Apparatus according to claim 3, wherein the diverter (4) comprises an essentially V-shaped portion (40) with the mounting portion (41) of the diverter (4) being formed at one end of the V-shaped portion (40) and with an outlet mouth portion (42) being formed at the other end of the V-shaped portion (40).
Apparatus according to claim 4, wherein all angles (43, 44, 45) included between the various portions (40, 41, 42) of the diverter (4) are about 30 degrees or multiples thereof.
Apparatus according to any one of the preceding claims, wherein the ratio (V2/V3) between the second driving speed (V2) and the third driving speed (V3) is between 1.3 and 2, preferably between 1.4 and 1.9, more preferably between 1.5 and 1.8 , and even more preferably between 1.6 and 1.7 .