EP1464239B1 - Method and apparatus for the production of a filter rod - Google Patents

Abstract

In a process to manufacture cigarette filter tips from elongated extruded fibres, the essentially separated fibres (27) are transported by air towards a conveyer (32). The fibres agglomerate to form a group of fibres, each fibre being in partial point contact with adjacent fibres to form a non-woven fleece resting on the conveyer surface. The fleece is transferred to an outer wrapping strip and then is rolled to form a cylindrical wrapper around the fibres, simultaneously compressing the fibres into a filter. Also claimed is a commensurate manufacturing assembly.

Description

The invention relates to a filter rod manufacturing method and a filter rod manufacturing apparatus, comprising a Aufschauervorrichtung by means of the individual filter materials are transported on a conveyor to form a nonwoven fabric, a format device in which a wrapping material is wound around the nonwoven fabric and a device for transferring the nonwoven fabric of the Conveyor on the format device.

A method for the preparation of filter materials and a corresponding apparatus for the preparation of filter materials for the production of filters of the tobacco processing industry are known from GB 718 332. In this process, snippets of a material are produced by means of a tobacco cutter and these are made of a stranding machine, similar to a cigarette rod making machine, wherein the chips are impregnated with a chemical agent to prevent undesirable taste and to prevent the chips from falling out of the end pieces of the correspondingly made filters. The cut chips are conveyed by means of a roller in the effective range of a spiked roller, and conveyed by means of the spiked roller from the roller on a conveyor belt to be subsequently fed to a further spiked roller, from which the chips are knocked out by means of another spiked roller and be supplied to a format in which the filter strand is formed with a wrapping strip. The snippets consist of materials such as paper, cellulose, textiles, synthetic materials or similar. and have a structure similar to cut tobacco.

Due to the shape of the chips, it is difficult to produce filters with homogeneous properties. In addition, the variability of the setting of the filter properties is only possible to a very limited extent.

From GB-A-2145918 a filter strand manufacturing apparatus is known in which fibers are torn out in Fig. 5 and the associated figure description by means of a roll of a fiber strand and are brought into the effective range of a transport air stream, which feeds the fibers of a strand manufacturing unit. Also disclosed are filter strand manufacturing apparatus in the other figures and associated text passages in which fibers are torn out of an endless feed of filter material through a respective drum, are popped on a conveyor belt and transferred to a strand forming unit. This happens, however, without transport air.

From US-A-3,644,078 there is disclosed a method of making a nonwoven fabric which initially produces singulated fibers and then these fibers are blown with a stream of air onto a conveyor, forming on the conveyor a nonwoven fabric.

US Pat. No. 3,050,427 discloses an apparatus for producing a nonwoven, wherein fibers are first comminuted and applied to a suction belt conveyor. While looking up at a suction belt or after shuddering as a fleece, the fibers are sprayed with binding material.

From US-A-4 966 170 a method and an apparatus are known, by means of which foamed material is supplied to tobacco, whereby the foamed material is dried, in particular in the production of cigarettes. The foam is introduced accordingly in the aufschauernden tobacco rod on the Saugstrangförderer.

US-A-2,931,076 discloses the production of fibrous sheets, pelts and mats from fibrous structures by means of an air-laying process.

US-A-3 792 943 shows the manufacture of a nonwoven fabric from natural or synthetic fibers such as wood fibers, textile fibers, glass and mineral wool fibers, asbestos fibers and the like, the fibers first being singulated and then applied to a conveyor by means of a transport air stream.

In contrast, it is an object of the present invention to develop a filter strand production process and a filter strand production device of the type mentioned in such a way that filters with more homogeneous filter properties can be produced.

• Transportieren endlicher, im Wesentlichen vollständig vereinzelter Fasern wenigstens einer Sorte mit Transportluft in Richtung eines Förderers,
• Bilden eines Faservlieses von sich wenigstens teilweise berührenden fasern aus den im Wesentlichen vollständig vereinzelten Fasern auf einer Oberfläche des Förderers
• Aufbringen des Faservlieses auf einen Umhüllungsstreifen, und
• Umhüllen des Faservlieses mit dem Umhüllungsstreifen, wobei beim oder nach dem Umhüllen des Faservlieses mit dem Umhüllungsstreifen Energie auf das Faservlies einwirkt, um eine feste Verbindung an den Berührungspunkten der Fasern zu erzeugen.

This object is achieved by a filter strand production process with the following process steps:

• Transporting finite, substantially completely separated fibers of at least one sort with transport air in the direction of a conveyor,
• Forming a fibrous web of at least partially contacting fibers from the substantially completely singulated fibers on a surface of the conveyor
• Applying the fibrous web to a wrapping strip, and
• Enveloping the fibrous web with the wrapping strip, wherein upon or after wrapping the fibrous web with the wrapping strip, energy acts on the fibrous web to produce a strong bond at the points of contact of the fibers.

In fact, according to the invention, it has been recognized that, in particular with transport air transported in the direction of a conveyor, substantially completely separated fibers, forming a nonwoven fabric on a surface of the conveyor, leading to a production of a filter strand with very homogeneous filter properties. The conveyor is in the context of this invention, in particular a belt conveyor and in particular preferably a suction belt.

When compacting the nonwoven fabric when wrapping the nonwoven fabric with the wrapping material strip, a uniform shaping of the filter strand is possible. When energy is applied thereto during or after the wrapping of the fibrous web with the wrapping material strip to produce a strong bond at the points of contact of the fibers, it is possible to make the filter relatively resilient and therefore Care must be taken to ensure that no fiber material falls out of the cut edges of the filter or filter element.

In the variant in which the fibers have a length which is shorter than a filter or filter element separated from the fiber strand produced, particularly homogeneous filter properties are possible. Preference is given to fibers of at least one fiber type, with an average fiber diameter in the range from 10 to 40 μm, in particular from 20 to 38 μm. The fibers which are preferably to be used are thus elongated and relatively thin. If it is preferable to add additives such as activated carbon granules, triacetin or latex to the fibers, the filter properties are particularly easy to adjust. Carbon reactive granules are added, for example, prior to complete singulation of the fibers or to the fibers being transported to the conveyor. Triacetin or latex as a binder are added, for example, to the quenched fiber fleece in the region of the conveyor.

If the nonwoven fabric is compacted prior to the step of applying to the wrapping strip, a particularly uniform compaction can be ensured. For this purpose, the compression preferably takes place both vertically and horizontally, that is, for example, from above and below as well as from the sides of the fiber fleece.

A particularly simple procedure is given when the nonwoven fabric for applying to the wrapping strip mechanically, in particular by means of compressed air, is detached from the conveyor.

Preferably, the fibrous web is formed prior to application to the wrapping strip. In this case, for example, the forming step may provide at least the formation of a semicircle transversely to the conveying direction of the nonwoven. Preferably, a full circle or oval is formed.

According to the invention, a filter or a filter element is produced according to the filter strand production method according to the invention by final cutting to length of the produced filter strand.

The object is further achieved by a filter strand manufacturing apparatus comprising a chiller device by means of which discrete filter materials are transported onto a conveyor to form a nonwoven on the conveyor, a format apparatus in which a wrapping material is wrapped around the nonwoven, and a device for transferring the nonwoven from the conveyor to the format apparatus, in that the Aufschaueryorrichtung by means of transport air allows transport of the filter materials in the direction of the conveyor, wherein a curing device is provided downstream of the transfer of the nonwoven fabric from the conveyor to the formatting device.

By transporting the separated filter materials by means of transport air, a particularly homogeneous nonwoven fabric can be produced, so that a particularly homogeneous filter strand and therefore particularly homogeneous filter or filter elements can be produced.

If at least one compacting device is provided in the region of the conveyor, the filter properties are to be positively influenced. For this purpose, the conveyor or a part of the conveyor is preferably part of the compacting device. A particularly easy to implement filter strand manufacturing device is given when the conveyor comprises at least one suction belt. If the fibers to be processed are so small that the openings of the suction belt clog quickly, it is advantageous to work with two additional Saugbändem, which are each arranged at approximately right angles on both sides of the first suction belt. A particularly effective transfer of the nonwoven fabric is done by means of compressed air, through which the nonwoven fabric is removable from the conveyor.

If the device for transferring the nonwoven fabric comprises a conveyor belt, it is possible to form the nonwoven fabric with respect to the properties of the filter to be produced or with respect to the shape of the filter to be produced accordingly. Preferably, the conveyor belt is a suction belt. A particularly preferred embodiment is given when the conveyor belt is bent transversely to the transport direction. In this way, for example, a filter strand which is round or oval in cross-section can be produced in a simple manner. For this purpose, preferably two conveyor belts are provided, which transport the fiber fleece between them. The conveyor belts are designed such that the nonwoven fabric is round or oval malleable. For this purpose, the conveyor belts, for example, each form a semicircle or a half oval.

An alternative transfer device is provided when the device for transferring the nonwoven fabric comprises a nozzle through which the nonwoven fabric is transportable. Preferably, the nozzle is designed such that the nonwoven fabric is round or oval malleable.

Fig. 1

eine dreidimensionale schematische Darstellung einer Vereinzelungsvorrichtung sowie eines Teils der Aufschauervorrichtung,

Fig. 2

eine schematische Ansicht einer erfindungsgemäßen Vorrichtung zur Filterstrangherstellung,

Fig. 3

einen Teil der Fig. 2 in einer Draufsicht in Richtung des Pfeils A,

Fig. 4

einen Teil der Fig. 2 in schematischer Darstellung in Seitenansicht, In Richtung des Pfeils B,

Fig. 5

eine schematische Ansicht einer weiteren erfinderischen Vorrichtung zur Filterstrangherstellung,

Fig. 6

einen Teil der Fig. 5 in einer Draufsicht in Richtung des Pfeils A,

Fig. 7

einen Teil der Fig. 5 in schematischer Darstellung in Seitenansicht, in Richtung des Pfeils B,

Fig. 8

eine schematische Ansicht eines Teils einer erfindungsgemäßen Vorrichtung zur Filterstrangherstellung, bei der Teile zur Vereinfachung weggelassen wurden,

Fig. 9

eine Draufsicht auf die Vorrichtung gemäß Fig. 8 in schematischer Darstellung, ohne Vereinzelungsvorrichtung,

Fig. 10

einen Teil einer Ausführungsform einer erfindungsgemäßen Filterstrangherstellvorrichtung in schematischer dreidimensionaler Darstellung,

Fig. 11

eine schematische Ansicht eines Tells einer erfindungsgemäßen Filterstrangherstellungsvorrichtung und

Fig. 12

eine weitere Ausführungsform eines Teils einer erfindungsgemäßen Filterstrangherstellungsvorrichtung in einer weiteren schematischen Ansicht.

The invention will now be described with reference to the drawings, to which reference is otherwise expressly made with respect to all details of the invention not explained in detail in the text.
Show it:

Fig. 1

a three-dimensional schematic representation of a separating device and a part of the Aufschauervorrichtung,

Fig. 2

a schematic view of a device according to the invention for filter rod production,

Fig. 3

2 a part of a plan view in the direction of the arrow A,

Fig. 4

2 shows a schematic representation in side view, in the direction of the arrow B,

Fig. 5

a schematic view of another inventive apparatus for filter rod production,

Fig. 6

5 is a plan view in the direction of the arrow A,

Fig. 7

5 shows a schematic representation in side view, in the direction of the arrow B, FIG.

Fig. 8

a schematic view of a portion of a device according to the invention for filter strand production, in which parts have been omitted for simplicity,

Fig. 9

8 shows a plan view of the device according to FIG. 8 in a schematic illustration, without a separating device, FIG.

Fig. 10

a part of an embodiment of a filter strand manufacturing device according to the invention in a schematic three-dimensional representation,

Fig. 11

a schematic view of a Tell a filter strand manufacturing device according to the invention and

Fig. 12

a further embodiment of a portion of a filter strand manufacturing device according to the invention in a further schematic view.

In Fig. 1, a separating device 10 is shown in a schematic three-dimensional representation. This is a variant of a separating device 10 according to the invention, which in of another European patent application (Ref .: 03 007 672.3) filed by the Applicant entitled "Process for the preparation of finite fibers and finisher for use in the production of filters" on the same date as this application was filed with the European Patent Office. The content of patent application filed on the same date, Ref .: 03 007 672.3, is intended to be incorporated in full in the disclosure of this patent application. The subject of this patent application filed on the same date is to treat fibrous material intended for use in the manufacture of filters accordingly to obtain substantially completely separated fibers and thus a homogeneous filter strand to be made from these fibers. The separating device 10 from FIG. 1 is used for this purpose. the filter material or fiber material is already vorvereinzelt in advance and dosed accordingly.

The essentially unaccurate fiber material or fiber / fiber group mixture 49 is, for example, as shown schematically in FIG. 4, moved via a stowage shaft 44 and feed rollers 46 into the effective range of a spiked roller 76 which contains the fiber / fiber group mixture vorvereinzelt ausschlagt. This fiber / fiber group mixture 49 is then gem by the air streams 19 in the screening drums 21. Fig. 1 transported. This takes place via lateral openings 20 in the housing 22. The fiber material is blown in the direction of the longitudinal axes of the screening drums 21. The two-sided blowing of the fiber material counterclockwise results in a circumferential annular flow 23. The annular flow 23 is superimposed by a flow normal or substantially perpendicular to this, which is caused by a vacuum applied to the fluidized bed 14 and an air flow 13. Airflow 13 is an option for larger, heavier fibers, which is not always necessary. The negative pressure prevailing at the fluid bed end 14 is created by the negative pressure in a suction belt conveyor, not shown, which is arranged at the fluidized bed end 14 and the other by the air flow 17, which is conveyed through the suction 16. The normal flow starts above the sieve drums 21 and begins and passes through the sieve drums 21 via their shell openings. The normal flow then passes into the fluidized bed region 11 and passes through it to the end of the 14th

The ununsulated or substantially unaccompanied fiber material passes in the drums 21 on the inner circumferential surfaces of the drums 21. The drums 21 rotate in a direction of rotation 24 of the screening drums 21 in a clockwise direction. The essentially unaccurate fiber material mounted on the drum shell surfaces is fed to the separating rollers 26 by the rotating drums. The separating rollers 26 rotate in the direction of rotation 25 counterclockwise. It would also be possible as an alternative, a clockwise rotation. It can also be used all other elastic rotary variants. The separating rollers 26, which may be formed as needle rollers, detect the unclassified fiber groups and tear and accelerate them. The fiber groups are thrown so long against the inner surface of the drums 21 until they have dissolved in individual fibers and have passed the shell openings or can pass through the shell openings. Instead of a sieve drum 21, a drum with perforated plates or Rundstabgitter can be provided.

The fibers or individual fibers are detected by an air flow and guided or sucked through the radial openings of the drum. The air flow conveys the fibers down to the fluidized bed. Once the fiber-laden flow has reached the fluidized bed, it is deflected and guided along the curved fluidized bed. Due to the centrifugal forces acting on the fibers, the fibers move to the curved guide wall and flow to the suction belt conveyor.

The air flowing in above the fibers is deposited on the wedge or separator 70 and discharged via the suction connection 71.

In Fig. 1, the corresponding fiber streams 18 are shown schematically. Optionally, individual fibers are detected by an air stream 13 emerging from the nozzle bar 12 and are also supplied to the fluid bed end 14 accordingly. Several nozzle bars can also be provided.

Fiber groups that were not or not completely separated by a single drum passage through the drums 21, go with the ring flow 23 in the respective parallel drum 21. The singulation device shown in Fig. 1 corresponds at least partially to that described in WO 01/54873 A1 or US Pat. No. 4,640,810 A from Scanweb, Denmark, or USA. The disclosure of the aforementioned patent application or of the aforementioned US patent is intended to be incorporated in full in the disclosure content of this patent application.

The separation is done essentially by interaction of the drums 21 with the rollers and an air flow and in particular by the fact that only isolated fibers have the opportunity to pass through the openings of the drum 21. The fiber streams 18, which are given by transport air, lead the separated fibers in the direction of the fluidized bed end 14, wherein the distance to the fluidized bed 11 due to the centrifugal force is getting smaller. In order to separate air from the fibers, the flow divider 15 is provided.

FIG. 2 shows a schematic view of a strand production machine 9.
FIG. 3 shows a part of the strand production machine 9 according to the invention from FIG. 2 in a plan view in the direction of the arrow A of FIG. 2, and FIG
FIG. 4 shows a side view of the strand production machine 9 according to the invention. Fig. 2 in the direction of arrow B.

The unaccurate fiber material 49 passes via the stowage shaft 44 to the metering device 46 or 76, comprising two feed rollers 46, a metering channel which is arranged between the feed rollers 46 and the spiked roller 76 and a spiked roller 76. The direction of the material entry 47 is shown in FIG in drawing plane down, as shown schematically there. The unclarified fiber material 49 is separated in the separation chamber 10. The separation takes place by an interaction of the separating rollers 26 with an air flow 50 and openings in a grid 77, which separates the separation chamber 10 from the space associated with the fluidized bed 11. The air flow generated by the air flow in the exhaust pipe 16 on the fluidized bed 11 promotes the separated fibers 27. The air flow 17 in the exhaust pipe 16 is with respect to its direction in Fig. 3 up out of the plane, as shown in Fig. 3. The air flow 17 also transports excess fibers. The air flow 28 serves to hold the fibers 27 which have been quenched on the suction belt 43 of the suction belt conveyor 32.

The separated fibers 27 move on the fluidized bed 11 in the direction of the fluidized bed end 14, on which a suction belt conveyor 32 is arranged. In Saugbandförderer 28 prevails by continuous air suction vacuum. This air suction is shown schematically by the air flow 28. The negative pressure sucks the separated fibers 27 and holds them on the air-permeable suction belt of the suction belt conveyor 32.

The suction belt 43 moves in the direction of strand production machine 9, that is, in Fig. 2 to the left. A fiber cake 29, which increases in size almost linearly with respect to the stranding machine 9, is formed the suction belt. The heaped-up fiber stream 29 has different strengths and is trimmed at the end of the filling zone of the suction belt conveyor by trimming by a trimming device 31 to a uniform thickness. The trimming device 31 may be a mechanical one, such as trimmer discs or a pneumatic one, for example, air nozzles. The mechanical trim is known per se in cigarette rod making machines. The pneumatic trimming is done in such a way that at the end of the fiber stream 29 a nozzle is arranged horizontally, from which an air jet emerges and tears a part of the fiber stream 29, so that excess fibers 30 are removed. It can find a spot jet nozzle or a flat jet nozzle use.

After trimming, the fiber stream 29 is split into a trimmed fiber strand 33 and a strand of excess fibers 30. It is also possible to grasp and tear away all fibers below a trim level from a jet. The excess fibers are returned to the fiber preparation process and later re-formed into a fiber strand.

The trimmed fiber strand 33 is held on the suction belt 43 and moved in the direction of the stranding machine 9. The trimmed fiber strand 33 is a loose nonwoven fabric which is compressed by a compacting belt 35. Instead of the compacting belt 35, a roller, such as, for example, a press disk 55 (see, for example, FIG. It can also be used several bands or rolls or discs use. There is also a lateral compression of the fiber cake, as shown in particular by Fig. 3. In Fig. 3, the compression belts 48 are shown, which are conical to each other, in Saugbandgeschwindigkeit with the fiber cake. The toothed shape of the compression bands 48 create zones of different density in the compacted fiber cake. In the higher density zones, the filter strand is cut later. The higher fiber density in the filter end area ensures a more compact cohesion of the fibers in this sensitive zone and also a better processing of the filter rods. For compressing in the vertical direction In Fig. 2, a compression belt 35 is provided.

The trimmed and compacted fiber strand 34 is transferred to the stranding machine 9. The transfer takes place by detaching the compacted fiber strand 34 from the suction belt 43 and placing the fiber strand 34 on a format strip or on a wrapping material strip which is applied to a format strip of the stranding machine 9. The format tape is not shown in the figures. This can be a conventional format strip which is also used in a normal filter rod machine or cigarette rod machine. The transfer is supported by a nozzle 36 directed from above onto the compacted fiber strand 34 and through which an air flow 37 flows. In the stranding machine 9, a fiber filter strand 38 is formed, wherein from a bobbin 41, a wrapping material strip 42 is withdrawn and wound around the fiber material as usual. By volume reduction and circular shaping or oval shaping of the compacted fiber strand 34 when wrapping with the wrapping material strip 42 or, as will be shown below, before wrapping with the wrapping material strip, a certain internal pressure builds up in the fiber filter strand 38.

In the curing device 39, binding components contained in the fiber mixture are superficially heated and fused. Similarly, the outer layers of bicomponent fibers that may be included in the fiber blend may also be fused to form a bond between the fibers. Reference is made in particular to the patent application of the applicant DE 102 17 410.5. As fiber materials, a variety of fibers can be used, which are suitable for the desired filter properties. As Fasermaterlallen come, for example, cellulose acetate, cellulose, carbon fibers and multicomponent fibers, especially bicomponent fibers. With regard to the components in question, reference is made in particular to DE 102 17 410.5 of the Applicant, which is to be included in the disclosure content of this application.

The different types of fiber are preferably mixed prior to strand formation. It is also possible to add at least one additive. The additive is, for example, a binder such as latex or triacetin or granular material which binds components of the cigarette smoke particularly effectively, such as, for example, activated carbon granules.

It is particularly preferred if the fiber length of the fibers used is smaller than the length of the filter or filter element to be produced. The length of the fibers should therefore be between 0.1 mm and 30 mm and in particular between 0.2 mm and 10 mm. The length of the filter to be produced is a conventional filter for a cigarette or a filter segment in multi-segment filters of cigarettes. In addition, if the average fiber diameter in the range of 10 to 40 .mu.m, in particular 20 to 38 microns and more preferably between 30 and 35 microns, a very homogeneous filter can be produced.

The curing device 39 may include a microwave heater, a laser heater, heating plates or sliding contacts. By heating the binding components, for example, the outer layer of bicomponent fibers or latex, the individual fibers combine in the fiber strand and merge superficially. The curing device 39 may also allow for drying of binder added in liquid form. Upon cooling of the fiber strand, the melted areas of the heated binding components harden again. The resulting lattice framework gives the fiber strand stability and hardness.

Finally, the cured fiber filter strand 38 is cut into filter rods 40. The curing of the filter is also possible after cutting into the filter rods 40.

5 shows a further embodiment according to the invention of a strand production machine 9 in a schematic representation. 6 shows a part of the strand-making machine 9 in a plan view in the direction of the arrow A of FIG. 5, and FIG. 7 shows a side view of the strand-making machine 9 according to FIG. 5 in the direction of the arrow B.

In contrast to the strand production machine 9 gem. 2 to 4, the singulated fiber material 27 is thrown onto the suction belt 43 from above in this exemplary embodiment, specifically in the transport direction 74. The separating device 10, which is also shown schematically in FIGS. 5 to 7, represents a modified form of the separating device 10 In the separating chamber 45 are screening drums 21 which rotate in the direction of the arrow. There are also separating rollers 26 in the form of spiked rollers; However, these are arranged in a modification of FIG. 1, relatively centrally in the screening drums 21. The spiked rollers 26 are also used in this case to beat apart the not yet isolated fiber material or the contiguous fiber groups in individual fibers, so that the separated fibers can pass through the outlet openings of the screen drum 21 in the hopper 53. By the corresponding air streams and in this case also the gravity, then the isolated fibers 27 reach into the region of the suction belt conveyor 32, which is configured in this case with Saugbandwangen 57.

A corresponding fiber stream 29 is thrown on the suction belt 43. Excess fiber material 30 is removed by a trimmer 31 from the remaining fiber strand 33 above it. The trimmed fiber strand 33 is pressed by means of a pressure washer 55, the at the same time in the conveying direction of the strand rear Umlenktrum the suction belt 43 'is compressed. Shortly behind the press disk 55, the compacted fiber strand 34 is held by a suction belt 43 'from above. For this purpose, a negative pressure field 54 is generated by means of an air flow 28. In order to enable a detachment of the suction belt 43 ', an air flow 37 is provided, which hits through the nozzle 36 on the suction belt. The compacted fiber strand 34 is then removed from the suction belt 43 'by means of an air flow 37 through the nozzle 36 and transferred to a format 56. For this purpose, the compacted fiber strand 34 as usual reaches a wrapping material strip 42, which is conveyed on a format strip. The remaining process steps correspond to those according to FIGS. 2 to 4.

FIG. 8 shows a part of a device according to the invention in a schematic view. The suction belt 43 is deflected around deflection rollers 59. The fiber stream 29, which is gradually built up, becomes the trimmed fiber strand 33 after trimming. The trimming device is not shown in this illustration of FIG. In the region of the churning of the fiber strand 29, individual fibers 27 reach the fiber strand from below.

Subsequently, the fiber strand 33 reaches a wrapping material strip 42, which arrives at a format belt 58. The format band 58 and the wrapping material strip 42 are deflected by corresponding rollers 59. In the area of the roller 61, the fiber strand 44 reaches the wrapping material strip 42. At this point, the beginning of the format 56 is wound in the usual manner of the wrapping material strip 42 around the fiber strand 33.

In Fig. 9 is a plan view of the device of Fig. 8 is shown, in particular a particularity of the side cheeks 57 is disclosed. The side cheeks 57, which also border on the fiber strand 29 or 33, are designed as suction belts 43, which in turn are again around deflection rollers 59 are deflected. For particularly small and thin fibers, it may be necessary to provide not only a suction belt, but, as in this embodiment, three suction belts, so that the fiber material is held in accordance with the suction strand or the Saugsträngen.

Fig. 10 shows a schematic three-dimensional representation of a device for transferring the fiber strand from the suction belt 43 on the format 56 and in particular on the wrapping material strip 42. The fiber strand, which is not shown in this figure, comes from the lower portion of the suction belt 43, the is deflected over the guide roller 59, in the free space of the opposing belts 62nd

The bands 62, which may also be steel bands in particular, are curved and are correspondingly deflected around curved rollers 63. The configuration of the bands 62 results in a corresponding round cavity between two opposite bands 62. The fiber strand 34 passes through this hollow space with a round cross section and is placed on the wrapping material strip 42. By the transfer device, a preforming of the fiber strand 34 and possibly further compression is possible. In this embodiment, the Saugbandwangen 57 are designed as a solid side walls.

FIG. 11 shows a section of a strand production device 9 according to the invention in a schematic representation. The fibrous stream 29 of singulated fibers 27, which has been thrown up from above in a funnel 53, reaches the suction belt 43 and the operative area of a pressure belt 64, which is deflected around rollers 65. The correspondingly compacted fiber strand passes into a nozzle 66 and is further conveyed by means of an air stream 67 onto a wrapping material strip 42 which rests on a format belt 58. Subsequently, the fiber strand as usual with the Envelope material strip 42 is wrapped to form a fiber filter strand 38.

FIG. 12 shows a section of a further strand production device 9 according to the invention in a schematic representation. The fiber strand 33 conveyed by the suction belt 43 passes into the effective region of a nozzle 68, which applies compressed air 69 to the fiber strand in the region of the deflection roller 65 and thereby removes the fiber strand 33 from the suction belt 43. The angle of the nozzle or the compressed air acting on the fiber strand 33 is adjustable. After detachment of the fiber strand 33 from the suction belt 43, this passes into the annular nozzle 70. The air 67 flowing through the nozzle slot 71 can fulfill various functions, depending on the nozzle design. The function is always such that the vacuum prevailing in the nozzle inlet channel of the nozzle 70 dissolves the fiber strand 33 from the suction belt 43 running on the deflection roller 65, which may also be designed as a pressure disk 65. In addition, by impinging the compressed air 67 onto the fiber strand at certain angles, the fiber strand can allow the fiber strand to be conveyed into the first format-forming hollow cone 72. As a variant, it is possible that the compressed air 67 dissolves the strand into individual fibers or fiber groups and thus promotes the individual fibers or fiber groups in the first format-forming hollow cone 72. By the compressed air, the fiber strand or the individual fibers and fiber groups are conveyed into the first format-forming hollow cone 72 and then into the second format-forming hollow cone 73. Under the second format-forming hollow cone 73, the format strip 58 runs with the wrapping material strip 42 lying thereon. The second hollow cone 73 has a smaller taper than the first hollow cone 72. In the first format-forming hollow cone 72 are ventilation holes. These vent holes provide for the air separation of the nozzle air 69 and 67th

In the first case, in which the fiber strand 33 is transferred as a fiber strand, this is formed in the format-forming hollow cones 72 and 73, from the top and from the format in progress format tape 58 from below. The complete transfer of the fiber strand 33 to the format strip or wrapping material strip 42 takes place under the hollow cone 73. In the second variant in which individual fibers and fiber groups are pressed by the nozzle air 69 in the format forming hollow cone, it comes to a due to the taper of the hollow cone Jam of the individual fibers and fiber groups, so that forms a new fiber strand. The strand is formed completely in the second hollow cone 73 and transferred at the end of the second hollow cone 73 to the format strip or the wrapping material strip 42. Subsequently, the wrapping material strip 42 is wound around the strand as usual and sealed so as to form the fiber filter strand 38.

In contrast to the production of cigarette rods, the difficulty of the filter strand production acc. The invention is to form filter materials made of fine fibers with or without appropriate additives such as. Kohleaktivgranulat or powder in homogeneous filter strands. Accordingly, the various elements or devices are designed to optimally transport, hold or process the materials used.

The fibrous materials may be cellulosic fibers, thermoplastic starch fibers, flax fibers, hemp fibers, flax fibers, sheep wool fibers, cotton fibers or multicomponent fibers, in particular bicomponent fibers having a length smaller than the filter to be produced and having a thickness, for example. in the range of 25 and 30 microns. Thus, for example, cellulose fibers of the stora fluff EF type untreated from Stora Enso Pulp AB can be used which have an average cross section of 30 μm and a length of between 0.4 and 7.2 mm. As synthetic fibers such as bicomponent fibers, For example, fibers of the type Trevira 255 3.0 dtex HM with a length of 6 mm may be used by Trevira GmbH. These have a diameter of 25 microns. As other synthetic fibers, cellulose acetate fibers, polypropylene fibers, polyethylene fibers and polyethylene terephthalate fibers can be used. The additives can be found in the flavor or smoke-influencing materials, such as activated charcoal granules or flavoring agents, and also binders by means of which the fibers can be glued together.

LIST OF REFERENCE NUMBERS

9

Strand manufacturing apparatus

10

separating device

11

fluidized bed

12

nozzle bar

13

airflow

14

Fluidized bed end

15

flow divider

16

suction

17

airflow

18

fiber stream

19

airflow

20

opening

21

screen drum

22

casing

23

annular flow

24

Rotation direction of the sieve drum

25

Rotation direction of the separating roller

26

separating roller

27

isolated fibers

28

airflow

29

fiber stream

30

excess fibers

31

trimming device

32

suction belt

33

trimmed fiber strand

34

compacted fiber strand

35

compression band

36

jet

37

airflow

38

filter rod

39

curing

40

filter rod

41

reel

42

Wrapping material strip

43

suction belt

43

suction belt

44

accumulating shaft

45

separation chamber

46

feed roller

47

material input

48

compression band

49

Fiber / fiber group mixture

50

airflow

52

suction

53

funnel

54

Under pressure field

55

dummy block

56

format

57

Saugbandwange

58

format tape

59

idler pulley

61

role

62

tape

64

pressure belt

63

role

65

role

66

jet

67

airflow

68

jet

69

compressed air

70

ring nozzle

71

nozzle slot

72

1. hollow cone

73

2. hollow cone

74

Transport direction of the filter material

75

transport direction

76

spiked roller

77

grid

Claims (23)

1. Method for producing filter rod, comprising the following process steps:

   - transporting non-continuous, substantially completely singulated fibres (27) of at least one type by means of transportation air in the direction of a conveyor (32);

   - forming a fibrous web (29, 33, 34) of fibres (27) at least partially in contact with one another from the substantially completely singulated fibres (27) on a surface of the conveyor (32);

   - applying the fibrous web (29, 33, 34) to a wrapping strip (42), and

   - wrapping the fibrous web (29, 33, 34) with the wrapping strip (42), energy acting on the fibrous web (29, 33, 34) during or after the wrapping of the fibrous web (29, 33, 34) with the wrapping strip (42) in order to produce a firm connection at the contact points of the fibres (27).
2. Method for producing filter rod according to claim 1, characterised in that the fibrous web (29, 33, 34) is compacted during the wrapping of the fibrous web (29, 33, 34) with the wrapping strip (42).
3. Method for producing filter rod according to claim 1 or 2, characterised in that the fibres (27) have a length which is shorter than a filter (40) or filter element (40) cut from the fibre rod (38) produced.
4. Method for producing filter rod according to claim 3, characterised in that at least one type of fibre includes fibres (27) having a mean fibre diameter within the range from 10 to 40 µm, in particular from 20 to 38 µm.
5. Method for producing filter rod according to one or more of claims 1 to 4, characterised in that additives (60) are applied to the fibres.
6. Method for producing filter rod according to one or more of claims 1 to 5, characterised in that the fibrous web (29, 33) is densified prior to the step of application thereof to the wrapping strip (42).
7. Method for producing filter rod according to claim 6, characterised in that densification takes place along at least two axes perpendicular to the direction of movement.
8. Method for producing filter rod according to one or more of claims 1 to 7, characterised in that the fibrous web (29, 33, 34) is detached from the conveyor (32) mechanically, in particular by means of compressed air (37, 67), for application to the wrapping strip (42).
9. Method for producing filter rod according to one or more of claims 1 to 8, characterised in that the fibrous web (29, 33, 34) is shaped before application to the wrapping strip.
10. Method for producing filter rod according to claim 9, characterised in that the shaping step provides the formation of a semicircle transversely to the conveying direction of the web (29, 33, 34).
11. Method for producing filter rod according to claim 10, characterised in that a full circle is produced.
12. Method for producing filter rod according to one or more of claims 1 to 11, characterised in that the singulated fibres are separated at least partially from the transportation air (13) prior to formation of a fibrous web (29, 33, 34).
13. Apparatus for producing filter rod (9), comprising an updraught device (11, 53) by means of which singulated filter materials are transported on to a conveyor (32) to form a fibrous web (29, 33, 34) on the conveyor (32), a formatting device (56) in which a wrapping material strip (42) is wrapped around the fibrous web (29, 33, 34) and a device (36, 54, 62, 63, 66, 70, 72, 73) for transferring the fibrous web (29, 33, 34) from the conveyor (32) to the formatting device (56), the updraught device (11, 53) enabling the filter materials (27) to be transported in the direction of the conveyor (32) by means of transportation air, and a hardening device (39) being provided downstream of the transfer of the fibrous web (29, 33, 34) from the conveyor (32) to the formatting device (56).
14. Apparatus for producing filter rod according to claim 13, characterised in that at least one compacting device (35, 48, 55, 64) is provided in the region of the conveyor (32).
15. Apparatus for producing filter rod according to claim 13 or 14, characterised in that the conveyor (32) or a part of the conveyor (32) forms part of the compacting device (35, 48, 55, 64).
16. Apparatus for producing filter rod according to one or more of claims 13 to 15, characterised in that the conveyor (32) includes at least one suction belt (43).
17. Apparatus for producing filter rod according to claim 16, characterised in that the conveyor (32) includes at least three suction belts (43).
18. Apparatus for producing filter rod according to one or more of claims 13 to 17, characterised in that the fibrous web (29, 33, 34) is detachable from the suction belt (43) of the conveyor (32) by means of compressed air (37, 67, 69).
19. Apparatus for producing filter rod according to one or more of claims 13 to 18, characterised in that the device (36, 54, 62, 63, 66, 70, 72, 73) for transferring the fibrous web (29, 33, 34) includes a conveyor belt (62).
20. Apparatus for producing filter rod according to claim 19, characterised in that the conveyor belt (62) has a concave configuration.
21. Apparatus for producing filter rod according to claim 19 or 20, characterised in that two conveyor belts (62) are provided which transport the fibrous web (29, 33, 34) between them.
22. Apparatus for producing filter rod according to one or more of claims 13 to 21, characterised in that the device (36, 54, 62, 63, 66, 70, 72, 73) for transferring the fibrous web (29, 33, 34) includes a nozzle (66, 70, 72, 73) through which the fibrous web (29, 33, 34) is transportable.
23. Apparatus for producing filter rod according to claim 22, characterised in that the nozzle (66, 70, 72, 73) is so configured that the fibrous web (29, 33, 34) can be given a round or oval shape.

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