EP1763306B1

EP1763306B1 - Apparatus and method for the production of composite cigarette filters

Info

Publication number: EP1763306B1
Application number: EP05766773A
Authority: EP
Inventors: Cipriano Domenichini; Giovanni Severi; Marco Bonaveri
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2004-06-21
Filing date: 2005-06-20
Publication date: 2009-11-25
Anticipated expiration: 2025-06-20
Also published as: ATE449545T1; JP5017104B2; ES2334043T3; WO2006000918A2; PL1763306T3; BRPI0512308A; RU2007102069A; KR20070022731A; BRPI0512308B1; JP2008503231A; RU2372005C2; CN1972606B; CN1972606A; KR101229033B1; DE602005017892D1; EP1763306A2; WO2006000918A3

Abstract

Apparatus for the production of combined filters or recess filters for cigarettes is disclosed, the apparatus comprising: a feeder (12) for feeding a plurality of filter segments (2, 4) along a path; a wrapper downstream of the feeder (12) for wrapping the plurality of segments in a web of material (18) to form a rod (20); a combiner (52, 58, 68) operative at a location between the feeder (12) and the wrapper for forming a stream of aligned segments from the plurality of segments (2, 4) and for transporting the stream of aligned segments along the path to the wrapper, and cutting means (24, 28) for severing the rod (20) into a plurality of discrete rods each comprising a plurality of segments, the combiner (52, 58, 68) being adapted to maintain the alignment of segments in the stream of aligned segments as it transports the stream of aligned segments to the wrapper so that, in use, relative movement of the segments in the stream is substantially prevented over the entire length of the path from the combiner to the wrapper.

Description

The present invention relates to an apparatus and method for the production of rods comprising a plurality of segments and finds particular application in the manufacture of combined filters or recess filters for cigarettes. An example of such apparatus is disclosed in FR 1280722 .
Cigarettes typically comprise a wrapped tobacco column that optionally is tipped with a filter. The filter may be a composite multi-component filter comprising a plurality of filter rod segments. The filter rod segments making up the composite filter may include different base filter materials or may comprise the same base filter material, but with alternate segments being impregnated with a particulate material. Figure 1a shows a composite filter rod comprising alternating segments of cellulose acetate 2 and cellulose acetate impregnated with carbon particles 4. The composite filter may comprise segments consisting of air gaps, recesses or cavities adjacent to or between the other filter rod segments making up the composite filter, which may be filled with particulate or other material. Figure 2a shows a composite filter rod including segments of cellulose acetate 2, segments of cellulose acetate impregnated with carbon particles 4 and air gaps or cavities 6 interposed between neighbouring cellulose acetate segments 2. The plurality of dissimilar segments 2,4,6 of the composite filter rods shown in Figures 1a and 2a are fixed in position relative to each other by wrapping the composite filter rods in a glued paper wrapper known as plug wrap. Composite filters comprising a plurality of dissimilar filter rod segments including one or more air gaps or cavities are known as recess filters. Composite filters that do not include any air gaps are commonly termed combined filters.
It is known to manufacture cigarettes having combined or recess filters using a two-stage double-wrap process. In the first stage, a combining device is used to form a continuous stream of aligned alternating filter rod segments of two or more different types which is then wrapped in a web of plug wrap to form a continuous filter rod. The continuous filter rod is subsequently severed at regular intervals by a cutting mechanism to yield a succession of discrete composite filter rods. In the second stage of the process a tipping machine is used to join the discrete composite filter rods to pre-wrapped tobacco columns using tipping paper, to form cigarettes.
Typically the discrete composite filter rods produced in the first stage of the double-wrap process are of multiple unit length, that is they contain more than one composite filter each of which is combined with a tobacco column in order to form a cigarette. For example, a discrete composite combined filter rod produced in the first stage might contain a centrally located two-up first filter rod segment (a first filter rod segment of double unit length), flanked by a pair of one-up second filter rod sections. In the second stage of the double-wrap process, the discrete composite combined filter rod would then be joined at both ends to a wrapped tobacco column to form a two-up cigarette having a two-up filter at its centre. Finally, each two-up cigarette would be severed at the midpoint of the composite combined filter rod to yield two one-up filter cigarettes, each having a combined filter containing one of the second filter rod segments and one-half of the first filter rod segment.
The discrete recess filter rod shown in Figure 2a may be produced by forming a continuous filter rod comprising groups 8 of filter rod segments 2,4 separated by air gaps 6 and then cutting the continuous rod to the desired length. If the air gaps 6 are left unfilled, the discrete recess filter rod of Figure 2a may be cut in half centrally to produce a pair of two-up recess filter rods, each of which can then be cut in half centrally at the air gaps 6 to produce four individual one-up recess filters. Similarly, the discrete combined filter rod shown in Figure 1a, when cut into four sections of equal length, would produce four combined filters.
The filtration characteristics of composite cigarette filters depend upon the length of, and in the case of recess filters also the spacing between, the filter segments therein. In the double-wrap process described above, the precise position of each cut made in the continuous filter rod relative to the plurality of aligned filter rod segments therein is, therefore, extremely important as it determines the length of the outermost or external filter rod segment of the discrete composite filter rod produced.
Known apparatus for the production of composite filters suffers from the disadvantage that the plurality of filter rod segments making up the composite filter, having been assembled into the desired combined filter or recess filter configuration by the combining device, can shift slightly relative to one another before being wrapped in the web of plug wrap and thereby fixed in position. As a result, the filter rod segments making up the composite filter are not always in the correct position within the continuous filter rod at the point at which it is severed, resulting in the formation of discrete composite filter rods having external filter rod segments of differing length, as illustrated in Figure 1b. In the manufacture of recess filters using such known apparatus, the relative movement of filter rod segments prior to enclosure in the paper web can also give rise to variation in the length of the air gaps or cavities in the discrete recess filter rods produced, as illustrated in Figure 2b.
In such known apparatus, where as a result of relative movement of the filter segments the continuous filter rod is not severed in such a way that the composition of every discrete composite filter rod is the same, it is also known to continually monitor the length of the external filter segments of the discrete composite filter rods produced, and in the case of recess filters the length of the air gaps therein, in order to maintain quality standards. If the structure of a discrete composite filter rod is identified as not meeting predetermined criteria, the rod is marked as such, segregated from the remaining satisfactory discrete filter rods and rejected. The generation of waste "off-specification" discrete combined filter rods is undesirable.
In order to overcome the disadvantages associated with known apparatus, it would be desirable to provide apparatus for the production of composite cigarette filters that allows for increased precision during production of the external filter rod segment length of both combined filters and recess filters and/or of the length of the air gaps of recess filters.
It would also be desirable to provide apparatus for the production of composite cigarette filters which, while maintaining the same level of final composite filter quality, enables the machine speed of the apparatus to be increased.
Furthermore, it would be desirable to provide apparatus for the production of composite cigarette filters that gives rise to less waste during production in terms of "off-specification" combined filter rods than known apparatus.
In addition, it would be desirable to provide apparatus for the production of composite cigarette filters that requires less maintenance compared to known apparatus.
It would also be desirable to be able to simply modify existing known composite cigarette filter makers to have the desirable properties recited above and to adapt existing known combined cigarette filter makers to enable the production of both combined cigarette filters and recess cigarette filters.
According to the present invention there is provided apparatus for the production of rods comprising a plurality of segments, the apparatus comprising: a feeder for feeding a plurality of segments along a path; a wrapper downstream of the feeder for wrapping the plurality of segments in a web of material to form a rod; a combiner operative at a location between the feeder and the wrapper for forming a stream of aligned segments from the plurality of segments and for transporting the stream of aligned segments along the path to the wrapper, and cutting means for severing the rod into a plurality of discrete rods each comprising a plurality of segments, wherein the combiner is adapted to maintain the alignment of segments in the stream of aligned segments as it transports the stream of aligned segments to the wrapper so that, in use, relative movement of the segments in the stream is substantially prevented over the entire length of the path from the combiner to the wrapper, characterised in that the combiner is adapted to maintain the alignment of segments in the stream of aligned segments by means of suction, or comprises a plurality of spaced apart spacers for maintaining the alignment of segments in the stream of aligned segments, or both.
According to the present invention there is also provided a method for the production of rods comprising a plurality of segments, the method comprising the steps of: feeding a plurality of segments along a path to a first position; forming a stream of aligned segments from the plurality of segments at the first position; transporting the stream of aligned segments along the path from the first position to a second position; wrapping the stream of segments in a web of material to form a rod at the second position; and repeatedly severing the rod to produce a plurality of discrete rods each comprising a plurality of segments, wherein the method further comprises maintaining the alignment of segments in the stream of aligned segments during the transporting step so that relative movement of the segments in the stream is substantially prevented between the first and second positions, characterised in that the method comprises one or both of: (i) applying suction to the stream of aligned segments between the first and second positions; and (ii) inserting spacers between groups of one or more segments at the first position.
By reducing relative movement of rod segments, such as cigarette filter rod segments, during composite filter production, the method and apparatus of the invention enable higher quality standards to be maintained with respect to variation in length of external rod segments and/or air gaps compared to known methods and apparatus for composite filter production.
Furthermore, because of this reduction in relative movement of the rod segments, continuous monitoring of external rod segment length during composite filter production is unnecessary.

Brief Description of the Drawings

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

Figure 1a is a schematic representation of the filter rod segments in an exemplary combined filter rod;
Figure 1b shows variation in length of the external filter rod segments of the exemplary combined filter rod of Figure 1a, caused, for example, by imprecise cutting of a continuous combined filter rod;
Figure 2a is a schematic representation of the filter rod segments in an exemplary two-up recess filter rod;
Figure 2b shows variation in length of the air gaps of the exemplary recess filter of Figure 2a, caused, for example, by movement of the filter rod segments during formation of a continuous recess filter rod;
Figure 3 is a schematic representation of a known apparatus for producing discrete combined filter rods of the type shown in Figure 1a;
Figure 4 is a schematic representation of a known apparatus for producing discrete recess filter rods of the type shown in Figure 2a;
Figure 5 is a schematic representation of apparatus according to a first embodiment of the present invention for producing composite filters;
Figure 6 is a schematic representation of apparatus according to a second embodiment of the present invention for producing composite filters; and
Figure 7 is a schematic representation of apparatus according to a fourth embodiment of the present invention for producing combined filters.

Figure 3 shows a known apparatus for producing discrete combined filter rods, of the type sold under model no. ND-3 by Japan Filter Technology, Ltd. (JT Group), and manufactured by Sanjo Machine Works Ltd., of Japan. The known apparatus includes a combining device 10 comprising a delivery wheel 12 which arranges a plurality of dissimilar filter rod segments 2,4 onto a first endless belt conveyor 14 in a pre-selected desired configuration, such as that shown in Figure 1a. The dissimilar filter rod segments 2,4 are transported to the delivery wheel 12 from two or more magazines or hoppers by a series of conveyors, not shown. As the filter rod segments 2,4 are delivered onto the first endless belt conveyor 14 they are urged against one another to form a continuous stream 16. The first belt conveyor 14 transports the abutting filter rod segments 2,4 to the upper side of a continuous running paper web 18 drawn from a bobbin (not shown). The paper web 18, which has an adhesive applied to at least part of the upper side thereof, is then draped around the filter rod segments 2,4 by a garniture (not shown) to form a continuous wrapped composite combined filter rod 20. The continuous paper web 18 is drawn off the bobbin and transported by a second endless belt conveyor 22 downstream through and beyond the garniture to a cutting head 24. At the cutting head 24, the continuous composite filter rod 20 is severed at regular intervals to yield a succession of discrete combined filter rods 26. The cutting head 24 comprises a rotary knife 28 mounted for rotation at constant speed about an axis parallel to the longitudinal axis of the continuous composite filter rod 20. The rotary knife, with which the delivery wheel 12 is in phase, cuts a discrete combined filter rod upon each revolution. The cutting head 24 is in phase with a filter rod segment 2,4 when the filter rod segment is fixed in position by the paper web 18. When the known apparatus is operating at optimum set-up, any error in the position of the filter rod segment 2,4 occurring along the path from the point where the filter rod segment 2,4 is released by the combining device 10 to the point where it is wrapped and fixed in position by the continuous paper web 18 gives rise to the same error at the cutting head 24
Once the filter rod segments 2,4 have been wrapped in the paper web 18 to form the continuous filter rod 20 they are fixed in position relative to one another. However, during transport downstream from the delivery wheel 12 of the combining device 10 to the paper web 18 by the first endless belt conveyor 14, the filter rod segments 2,4 can move relative to one another. Additionally, any differences in speed between the first belt conveyor 14 and the second endless belt conveyor 22 can jostle the filter rod segments 2,4 as they are transferred onto the continuous paper web 18. Relative movement of the filter rod segments 2,4 prior to enclosure in the paper web 18 can result in the production of waste discrete combined filter rods having external filter rod segments of different length, as illustrated in Figure 1b. Since between the delivery wheel 12 and the point at which the filter rod segments 2,4 are fixed in the paper web 18 (typically a distance of about 40cm), each filter rod segment 2,4 is simply pushed against adjacent filter rod segments, any length variations in the individual filter rod segments 2,4 are summed up in the discrete combined filter rods 26 produced.
Figure 4 shows a known apparatus for producing discrete recess filter rods, of the type sold under model no. PTCM by Molins PLC of Milton Keynes, United Kingdom.
Like the known apparatus shown in Figure 3, the known apparatus shown in Figure 4 includes a combining device 30 comprising a delivery wheel 32, which deposits a plurality of filter rod segments 2,4 onto a first endless belt conveyor 34. The first endless belt conveyor 34 carries the filter rod segments 2,4 downstream to a spiral spacer drum 36 that also forms part of the combining device 30, which groups the filter rod segments 2,4 in a pre-selected desired recess configuration, such as that shown in Figure 2a, by creating air gaps 6 between groups 8 of segments 2,4. An endless transfer belt 38 adjacent to the spiral spacer drum 36 transports the groups 8 of filter rod segments 2,4 to the upper side of a continuous running paper web 40 drawn from a bobbin (not shown). The paper web 40, which has an adhesive applied to at least part of the upper side thereof, is then draped around the spaced groups 8 of filter rod segments 2,4 by a garniture (not shown) to form a continuous wrapped composite recess filter rod 42. As in the apparatus shown in Figure 3, the continuous paper web 40 is drawn off the bobbin and transported downstream by a second endless belt conveyor 48 through and beyond the garniture to a cutting head 44 having a rotary knife 46. At the cutting head 44, the continuous composite filter rod 42 is severed at regular intervals into discrete recess filter rods 50 by the rotary knife 46, the spiral spacer drum 36 of the combining device 30 being operated in phase with the rotary knife 46.
The distance over which the groups 8 of filter rod segments 2,4 are transported between the combining device 30 and the paper web 40 is reduced in the known apparatus shown in Figure 4 compared to the known apparatus shown in Figure 3. Although in isolation this might be expected to give rise to a corresponding decrease in variation in length of the external filter rod segments of the discrete recess filter rods 50 produced, the layout of the known apparatus shown in Figure 4 introduces other sources of error to the relative positioning of the groups 8 of filter rod segments 2,4 in the continuous composite filter rod 42. During transfer from the spiral spacer drum 36 of the combining device 30 to the transfer belt 38, the filter rod segments 2,4 are free to shift in position, either as a whole or relative to one another, prior to being fixed in place by the paper web 40. In addition, the design of the endless transfer belt 38, which is located above the groups 8 of filter rod segments 2,4, and air gaps 6 therebetween, is such that the paper web 40 cannot be folded around the segments 2,4 and air gaps 6 while they are beneath the transfer belt 38, instead the groups 8 of filter rod segments 2,4 must exit from beneath the transfer belt 38 before being fixed in position by the folded paper web 40. Between the end of the transfer belt 38 and the point at which they are fixed in the paper web 40, the groups 8 of filter rod segments 2,4 and the filter rod segments 2,4 within each group 8 are also free to move relative to one another.
Relative movement of the groups 8 of filter rod segments 2,4 prior to enclosure in the paper web 40 in the apparatus of Figure 4 can not only result in the production of waste discrete recess filter rods which have external filter rod segments of different length, but also in the production of waste discrete recess filter rods which have air gaps 6 of differing length, as illustrated in Figure 2b.
An apparatus for producing composite filters according to a first embodiment of the present invention is shown in Figure 5. The same reference numerals are used in Figure 5 to identify parts of the apparatus according to the invention that correspond to those of the known apparatus shown in Figure 3 already described.
The apparatus according to the first embodiment of the invention shown in Figure 5 differs from that of known apparatus of the type shown in Figure 3 in that it additionally comprises an endless transfer belt 52 mounted above the first endless conveyor belt 14 and the second endless conveyor belt 22, between the delivery wheel 12 and the cutting head 24. A plurality of evenly spaced spacers or teeth 54 are mounted on the outside of the endless transfer belt 52, the spacing between adjacent teeth 54 being equal to the length of a whole number of filter rod segments 2,4 fed onto the first endless belt conveyor 14 by the delivery wheel 12. The endless transfer belt 52 is driven by a powered pulley 56 in phase with the cutting head 24. To avoid slipping of the endless transfer belt 52 on the powered pulley 56 which could lead to variation in length of the external filter rod segments of the discrete filter rods produced, the endless transfer belt 52 may be provided on its inner surface opposite the teeth 54 with in-phase pins (not shown), which cooperate with correspondingly spaced in-phase holes (not shown) provided in the powered pulley 56. The endless transfer belt 52 and the teeth 54 may be formed from metal, rubber, plastic or other suitable material.
In use, as the filter rod segments 2,4 from the delivery wheel 12 are fed beneath the endless transfer belt 52 by the first endless belt conveyor 14, the teeth 54 on the endless transfer belt 52 separate the filter rod segments 2,4 into groups 8 of length equal to the spacing between the teeth 54, and then transfer the grouped filter rod segments 2,4 to the continuous running paper web 18. The paper web 18 is then folded around the groups 8 of filter rod segments 2,4 by a known folding mechanism such as a garniture (not shown) to form the continuous composite filter rod 20, which is subsequently severed at regular intervals by the rotary knife 28 of the cutting head 24 to form discrete composite filter rods.
During transport downstream from the delivery wheel 12 towards the paper web 18 by the endless transfer belt 52, the groups 8 of filter rod segments 2,4 are held in fixed relative position by the teeth 54 of the endless transfer belt 52. The distance over which the groups 8 of filter rod segments 2,4 must then be transferred before they are fixed in position by the folded paper web 18 is greatly reduced compared to the distance between the delivery wheel 12 and the point at which the filter plugs 2,4 are fixed in position in the folded paper web 18 in the known apparatus. By reducing this distance and thereby assuring more correct positioning of the filter rod segments 2,4 in the continuous composite rod 20, both with respect to each other and to the cutting head 24, the apparatus shown in Figure 5 decreases the variation of the length of the external filter segment and, in the case of recess filters, the air gap length 6 of the discrete composite rods produced compared to known apparatus.
The apparatus according to a first embodiment of the invention shown in Figure 5 can be used to make both discrete combined filter rods and discrete recess filter rods (unlike known apparatus such as that shown in Figure 3). For the production of discrete recess filter rods, the endless transfer belt 52 and the second endless belt conveyor 22, which transports the paper web 18, are driven at the same speed. The spacing 6 between the groups 8 of filter rod segments 2,4 achieved by the teeth 54 of the transfer belt 52 is thereby maintained as the grouped filter rod segments 2,4 are transferred to the paper web 18. Where, as illustrated in Figure 5, the apparatus is used for the production of discrete recess filter rods having the configuration shown in Figure 2a, the width of each tooth 54 is equal to the width of the air gap 6 in the recess filter and the spacing between adjacent teeth 54 is equal to the sum of the length of two cellulose acetate segments 2 and one cellulose acetate segment impregnated with carbon particles 4.
In order to produce discrete combined filter rods, the second endless belt conveyor 22 which transports the paper web 18 is driven at a reduced speed compared to the endless transfer belt 52. As the groups 8 of filter rod segments 2,4 are transferred by the teeth 54 of the endless transfer belt 52 to the paper web 18, the difference in speed between the endless transfer belt 52 and the second endless belt conveyor 22 causes the groups 8 of filter rod segments 2,4 to be pushed against each other thereby creating a continuous combined filter rod. It will be appreciated that when apparatus according to the first embodiment of the invention shown in Figure 5 is used to produce combined rather than recess filters, the width of the teeth 54 on the endless transfer belt 52 is not significant, depending on the difference in speed between the endless transfer belt 52 and the second endless belt conveyor 22.
In the known apparatus for producing discrete recess filter rods shown in Figure 4, the spiral spacer drum 36 groups the filter rod segments 2,4 together and creates the required air gaps 6 between them and then the endless transport belt 38 moves the grouped filter rod segments 2,4 towards the paper web 40. As already discussed with reference to Figure 4, transfer of the groups 8 of filter rod segments 2,4 between the spiral spacer drum 36 and the transfer belt 38 introduces an additional source of error in the relative positioning of the filter rod segments 2,4 in the continuous recess filter rod 42 produced. In the apparatus according to the first embodiment of the invention shown in Figure 5, the endless transfer belt 52 with teeth 54 performs the function of both the spiral spacer drum 36 and the transfer belt 38 of the known apparatus of Figure 4 and so avoids the introduction of this additional source of error.
Advantageously, the endless transfer belt 52 of the apparatus of Figure 5 may also be mounted for pivotal movement about powered pulley 56 thereby allowing for easier cleaning beneath the transfer belt 52, compared to the transfer belt 38 of the known apparatus of Figure 4, should filter rod segments 2,4 become jammed beneath the transfer belt 52 during production.
An apparatus for producing composite filters according to a second embodiment of the present invention is shown in Figure 6. The same reference numerals are used in Figure 6 to identify parts of the apparatus according to the second embodiment of the invention which correspond to those of the known apparatus already described.
The structure of the apparatus according to the second embodiment of the invention shown in Figure 6 differs from that of known apparatus such as that shown in Figure 3 in that it additionally comprises a transfer device 58 mounted above the first endless conveyor belt 14 and the second endless conveyor belt 22, between the delivery wheel 12 and the cutting head 24. In use, the transfer device 58 repetitively delivers filter rod segments 2,4 from the delivery wheel 12 to the continuous running paper web 18 at a location along the second endless conveyor belt 22 just upstream of a garniture or other known folding mechanism (not shown).
The transfer device 58 comprises three adjacent wheels 60,62,64, mounted for rotation about parallel axes perpendicular to the direction of movement of the filter rod segments 2,4 on the first endless belt conveyor 14. Each wheel 60,62,64 has a plurality of spaced rounded teeth 66 disposed around the circumference thereof, the spacing between adjacent 66 teeth on each wheel 60,62,64 being approximately equal to the length of a whole number of filter rod segments 2,4 fed onto the first endless belt conveyor 14 by the delivery wheel 12. The two outer wheels 60,64 of the transfer device 58 have a single row of teeth 66 disposed about their circumference, while the inner wheel 62 has a pair of opposed rows of teeth 66 disposed about its circumference. The three wheels 60,62,64 are mounted relative to one another in the transfer device 58 so that as, in use, the wheels 60,62,64 are rotated, the teeth 66 on the two outer wheels 60,64 pass between, the opposed rows of teeth 66 on the inner wheel 62 at the nips between the outer wheels 60,64 and the inner wheel 62. The wheels 60,62,
64 and the teeth 66 thereon are made from metal or other suitable material.
In use, as the filter rod segments 2,4 from the delivery wheel 12 are fed by the first endless belt conveyor 14 beneath the transfer device 58 of the apparatus of Figure 6 the teeth 66 on the first outer wheel 60 separate the filter rod segments 2,4 into groups 8 of length equal to the spacing between the teeth 66. As the first outer wheel 60 rotates the groups 8 of filter rod segments 2,4 held between the teeth 66 thereof are transported downstream towards the counter-rotating inner wheel 62. When the teeth 66 of the first outer wheel 60 are adjacent those 66 of the inner wheel 62, the groups 8 of filter rod segments 2,4 held between the teeth 66 of the first outer wheel are transferred to between the teeth 66 of the inner wheel 62. Further rotation of the inner wheel 62 then transports the groups 8 of filter rod segments 2,4 transferred from the first outer wheel 60 further downstream towards the counter-rotating second outer wheel 64. As the teeth 66 of the second outer wheel 64 interlock with those of the inner wheel 62, the groups 8 of filter rod segments 2,4 previously transferred from the first outer wheel 60 to the inner wheel 62, which are held between the teeth 66 of the inner wheel 62, are transferred to between the teeth 66 of the second outer wheel 64. Further rotation of the second outer wheel 64 transfers the groups 8 of filter rod segments 2,4 onto the continuous running paper web 18. The paper web 18 is then folded around the filter rod segments 2,4 by known folding mechanisms such as a garniture (not shown) to form a continuous composite filter rod 20, which is subsequently severed at regular intervals by the rotary knife 28 of the cutting head 24 to form discrete composite filter rods. The rotation of each of the three wheels 60,62,64 of the transfer device 58 of the apparatus of Figure 6 is in phase with the cutting head 24, resulting in precise cuts of the continuous composite filter rod 20 by the rotary knife 28.
By analogy with the operation of the apparatus according to the first embodiment of the invention shown in Figure 5, the apparatus according to the second embodiment of the invention shown in Figure 6 may be used to produce either discrete recess filter rods, by driving the second endless belt conveyor 22 and the wheels 60,62,64 of the transfer device 58 at the same speed to produce a continuous recess filter rod 20 having air gaps 6 of length equal to the width of the teeth 66 of the second outer wheel 64, or discrete combined filter rods, by driving the second endless belt conveyor 22 at a reduced speed compared to the wheels 60,62,64 of the transfer device 58 to produce a continuous combined filter rod 20, as desired.
To avoid jostling of the filter rod segments 2,4 during the manufacture of recess filter rods the wheels 60,62,64 of the transfer device 58 are driven such that the tangential speed of the second outer wheel 64 is essentially the same as that of the second endless belt conveyor 22 so that each group 8 of filter rod segments 2,4 is delivered from the second outer wheel 64 onto the continuous paper web 18 at little or no speed relative to the second endless belt conveyor 22.
The diameters of each of the wheels 60,62,64 of the transfer device 58, and the spacing between and the width or breadth of the teeth 66 thereon, may be varied to allow different machine speeds to be achieved and/or different filter types to be produced. For the production of recess filters, preferably, the breadth (arcuate length) of the teeth 66 of the inner wheel 62 and the second outer wheel 64 is equal to the desired width of the air gaps 6 between the groups 8 of filter rod segments 2,4 in the continuous recess filter rod 20. The breadth (arcuate length) of the teeth 66 of the first outer wheel 60 is preferably reduced compared to that of the inner wheel 62 and the second outer wheel 64 so as to create an increased spacing between the teeth 66 on the first outer wheel 60. The increased spacing between the teeth 66 of the first outer wheel 60 accommodates receipt of the filter rod segments 2,4 from the first endless belt conveyor 14, which, in use, is then driven at a speed greater than the tangential speed of the first outer wheel 60 at the nip therebetween.
Once a group 8 of filter rod segments 2,4 is established between the teeth 66 of the first outer wheel 60 it becomes registered with respect to other groups 8 upon transfer to the inner wheel 62. Any shifting of the groups 8 of filter rod segments 2,4 at the nip between the first outer wheel 60 and the inner wheel 62 being accommodated by the rounded profile of the teeth 66 and by the coincidence (superimposed relation) of the teeth 66 at the nip.
While in Figure 6 the rotational axis of the inner wheel 62 of the transfer device 58 is shown as being vertically offset relative to the rotational axes of the two outer wheels 60,64, it will be appreciated that the rotational axes of the wheels 60,62,64 may alternatively be in-line with one another. It will also be appreciated that while the apparatus according to a third embodiment of the invention shown in Figure 6 includes a transfer device 58 comprising three adjacent wheels 60,62,64, transfer devices comprising a different number of adjacent wheels could alternatively be employed.
Advantageously, the transfer device 58 of the apparatus of Figure 6 may also be mounted for pivotal movement about one end thereof, thereby allowing for easier cleaning beneath the wheels 60,62,64 of the transfer device 58, compared to the transfer belt 38 of the known apparatus of Figure 4, should filter rod segments 2,4 become jammed beneath the wheels 60, 62, 64 during production.
During transport downstream from the delivery wheel 12 towards the paper web 18 by the transfer device 58, the groups 8 of filter rod segments 2,4 are held in fixed relative position by the teeth 66 of the three wheels 60,62,64. The distance over which the filter rod segments 2,4 can shift slightly relative to one another or be jostled is, therefore, once again greatly reduced compared to the known apparatus shown in Figure 3. By reducing this distance and by using a single transfer device 58 to perform the functions of both the spiral spacer drum 36 and the transfer belt 38 of the known apparatus of Figure 4, the apparatus shown in Figure 6 provides the same advantages over known apparatus of the type shown in Figures 3 and 4 already identified and discussed in connection with the apparatus according to the first embodiment of the invention shown in Figure 5. In addition to these advantages, the apparatus according to the second embodiment of the invention shown in Figure 6 also requires less maintenance compared to the known apparatus of the type shown in Figure 4, since it does not include a transfer belt.
Apparatus for producing composite filters according to a third embodiment of the present invention has the same general structure and mode of operation as the apparatus according to the second embodiment of the invention shown in Figure 6. The structure of the apparatus according to the third embodiment of the invention differs, however, from that of the apparatus according to the second embodiment of the invention in that the wheels 60,62,64 of the transfer device 58 are provided with a plurality of holes about their circumference, in place of, or in addition to, teeth 66. The plurality of holes are arranged in groups which are evenly spaced about the circumference of the wheels, each group comprising two or three adjacent holes arranged in a line parallel to the rotational axis of the wheel. In use, air is drawn through the holes in order to transfer the filter rod segments 2,4 from the first endless conveyor belt 14 to the first outer wheel 60 and to deliver the filter rod segments from the first outer wheel 60 to the inner wheel 62 and from the inner wheel 62 to the second outer wheel 64. The filter rod segments 2,4 are transferred downstream from one wheel of the transfer device 58 to the next by releasing the suction applied to holes of the upstream wheel as they rotate through the nip between the upstream wheel and the next wheel. The filter rod segments 2,4 are similarly transferred from the second outer wheel 64 of the transfer device 58 to the second endless belt conveyor 22 by releasing the suction applied to holes of the second outer wheel 64 as they rotate through the nip between the second outer wheel 64 and the second endless belt conveyor 22.
The suction applied to the holes on wheels 60,62,64 holds the filter rod segments 2,4 in position as they are transferred by the wheels to the paper web 18, preventing their relative movement. Consequently, the distance over which the filter rod segments 2,4 are free to move relative to one another or to be jostled is once again greatly reduced compared to known apparatus of the type shown in Figure 3, and the apparatus according to the third embodiment of the apparatus provides the same advantages over known apparatus of the type shown in Figures 3 and 4 already identified and discussed in connection with the apparatus according to the second embodiment of the invention shown in Figure 6.
To facilitate transfer of filter rod segments in apparatus according to the second and third embodiments of the invention, ploughs may be positioned at the nip between the first endless belt conveyor 14 and the first outer wheel 60 of the transfer device 58, at the nip between the first outer wheel 60 and the inner wheel 62 of the transfer device 58, at the nip between the inner wheel 62 and the second outer wheel 64 of the transfer device 58 and/or at the nip between the second outer wheel 64 of the transfer device 58 and the second endless belt conveyor 22.
An apparatus for producing combined filters according to a fourth embodiment of the present invention is shown in Figure 7. Once again, the same reference numerals are used in Figure 7 to identify parts of the apparatus according to the invention that correspond to those of the known apparatus already described.
The structure of the apparatus according to the fourth embodiment of the invention shown in Figure 7 differs from that of the known apparatus shown in Figure 3 in that it additionally comprises a an endless suction belt 68 mounted above the first endless conveyor belt 14 and the second endless conveyor belt 22, between the delivery wheel 12 and the cutting head 24, which is driven at the same speed as the second belt conveyor 22.
In use, as the abutting filter rod segments 2,4 delivered onto the first endless belt conveyor 14 by the delivery wheel 12 reach the upstream end of the suction belt 68 they are held against the belt 68 by the suction applied thereto and transported downstream towards the continuous running paper web 18. At the downstream end of the belt, the suction is released and the filter plugs 2,4 are deposited on the paper web 18, which is then folded around them using a known folding mechanism such as a garniture (not shown) to form a continuous combined filter rod 20. The continuous combined filter rod 20 is subsequently severed into discrete combined filter rods 26 by the rotary knife 28 of the downstream cutting head 24.
In the apparatus of Figure 7, the filter rod segments 2,4 are held in fixed relative position by the suction belt 68 along their entire path from the delivery wheel 12 to the downstream end 72 of the suction belt 68, where they are released and wrapped and glued in place by the paper web 18. Movement of the filter rod sections 2,4 with respect to each other, or with respect to the paper web 18 and cutting head 24, is thereby prevented. The precision of the external filter segment length of the discrete composite rods produced using the apparatus according to the invention shown in Figure 7 is, therefore, increased, and the level of waste generated during production reduced, compared to known apparatus of the type shown in Figures 3 and 4.
It will be appreciated that a plurality of evenly spaced teeth may similar to those of the first embodiment, shown in Figure 5, may be provided on the outside of the endless suction belt 68 of the apparatus according to the fourth embodiment of the apparatus shown in Figure 7.
In contrast to known apparatus of the type shown in Figures 3 and 4, the operating speed of the apparatus according to the first, second, third and fourth embodiments of the invention can be increased without any resultant decrease in quality of the discrete composite filter rods produced; in known apparatus of the type shown in Figures 3 and 4, the reliability of the length of the external filter rod segments of the discrete composite filter rods produced decreases even further with increasing machine speed.
It will be appreciated that apparatus according to the invention may be used to produce composite filter rods having different structures to those shown in Figures 1a and 2a. For example, apparatus according to the invention may be used to produce a recess filter rod of the type shown in Figure 2a wherein the group 8 is a single cellulose acetate filter segment. Additionally, the progression of filter rod segments supplied to the apparatus by the delivery wheel may include alternating filter rod segments of different lengths and/or types. Furthermore, the air gaps 6 in recess filter rods made by apparatus according to the invention may be filled with carbon and/or other adsorbent materials by means of any known delivery device, for example by means of a carbon-delivery device mounted between the third wheel 64 and the garniture or other known folding mechanism of the apparatus according to the second embodiment of the invention shown in Figure 6.

Claims

Apparatus for the production of rods comprising a plurality of segments, the apparatus comprising:
a feeder (12) for feeding a plurality of segments (2,4) along a path;

a wrapper downstream of the feeder (12) for wrapping the plurality of segments in a web of material (18) to form a rod (20);

a combiner (52,58,68) operative at a location between the feeder (12) and the wrapper for forming a stream of aligned segments from the plurality of segments (2,4) and for transporting the stream of aligned segments along the path to the wrapper, and

cutting means (24, 28) for severing the rod (20) into a plurality of discrete rods each comprising a plurality of segments,

wherein the combiner (52,58,68) is adapted to maintain the alignment of segments in the stream of aligned segments as it transports the stream of aligned segments to the wrapper so that, in use, relative movement of the segments in the stream is substantially prevented over the entire length of the path from the combiner to the wrapper,

characterised in that the combiner (68) is adapted to maintain the alignment of segments in the stream of aligned segments by means of suction, or comprises a plurality of spaced apart spacers (54,66) for maintaining the alignment of segments in the stream of aligned segments, or both.
Apparatus according to claim 1 wherein the combiner comprises an endless belt (52,68) mounted for movement in part parallel to the path.
Apparatus according to claim 2 wherein the outer surface of the endless belt (52) has a plurality of longitudinally spaced apart spacers (54).
Apparatus according to claim 3 or 4 wherein the surface of the endless belt (68) has a plurality of holes through which, in use, a vacuum may be drawn.
Apparatus according to claim 1 wherein the combiner (58) comprises at least one wheel (60,62,64) mounted for rotation about an axis perpendicular to the path.
Apparatus according to claim 5 wherein the outer surface of the or each wheel (60,62,64) has a plurality of circumferentially spaced apart spacers (66).
Apparatus according to claim 6 wherein the spacing between adjacent spacers (66) on a wheel (60) of the combiner (58) proximate the feeder (12) is greater than the spacing between adjacent spacers (66) on the other wheels (62,64) of the combiner (58).
Apparatus according to claim 3, claim 4 when dependent on claim 3 or according to claim 6 or 7 wherein the spacing between adjacent spacers (54,66) is approximately equal to the length of a whole number of segments (2,4).
Apparatus according to claim 3, claim 4 when dependent on claim 3 or according to claim 6, 7 or 8 for the production of rods comprising a plurality of segments wherein one or more of the segments is an air gap (6) wherein the width of each spacer (54,66) is approximately equal to the width of the air gap (6).
Apparatus according to any of claims 5 to 9 wherein the circumferential surface of the or each wheel (60,62,64) is provided with a plurality of holes through which, in use, a vacuum may be drawn.
A method for the production of rods comprising a plurality of segments, the method comprising the steps of:
feeding a plurality of segments (2,4) along a path to a first position;

forming a stream of aligned segments from the plurality of segments (2,4) at the first position;

transporting the stream of aligned segments along the path from the first position to a second position;

wrapping the stream of segments in a web of material (18) to form a rod (20) at the second position; and

repeatedly severing the rod (20) to produce a plurality of discrete rods each comprising a plurality of segments (2,4,6),

wherein the method further comprises maintaining the alignment of segments in the stream of aligned segments during the transporting step so that relative movement of the segments in the stream is substantially prevented between the first and second positions

characterised in that the method comprises one or both of: (i) applying suction to the stream of aligned segments between the first and second positions; and (ii) inserting spacers (54,66) between groups (8) of one or more segments (2,4) at the first position.
A method according to claim 11 comprising forming a stream of aligned segments comprising spaced apart groups (8) of one or more segments (2,4) from the plurality of segments at the first position.
A method according to claim 11 or 12 for the production of rods comprising a plurality of segments wherein one or more of the segments is an air gap (6).
A method according to claim 11, 12 or 13 for the production of cigarette filters comprising a plurality of filter rod segments.