TECHNICAL FIELD

The present invention relates to a method and filter assembly machine for producing filter-tipped cigarettes .

BACKGROUND ART

As described, for example, in Patent Application GB2241866A1, filter-tipped cigarettes are produced on a filter assembly machine, which defines internally a path, along which elongated tobacco articles are fed transversely. The filter assembly machine is fed at the input with a succession of double cigarette portions, which, as they move transversely along the path through a cutting station, are each cut into two coaxial single cigarette portions. The single cigarette portions from each double cigarette portion are then parted axially and separated by inserting a double- filter fed onto the double cigarette portion conveyor line by a separate feed line, and which forms, with the two single cigarette portions, an assembly comprising two side by side filter-tipped cigarettes. At a rolling station, the component parts of each assembly are connected integrally by a gummed band, the centre portion of which covers the double filter, and the end portions of which cover the facing ends of the two single cigarette portions .

As anyone skilled in the art knows, the rolling operation is a highly critical stage, the speed of which depends directly on the output capacity of the filter assembly machine, and which, over and above a given maximum speed, results in tobacco fallout from the open ends of the single cigarette portions.

To increase the output of the filter assembly machine for a given rolling speed (i.e. without increasing the rolling speed, to preserve the integrity of the open ends of the single cigarette portions) , it has been proposed to reduce the spacing with which the assemblies are fed to the rolling station. Patent US5474091A1, for example, proposes reducing the spacing of the groups, just prior to rolling, to a minimum just slightly greater than the length of the bands employed

(below this minimum, the band of one assembly would interfere with the adjacent assembly) .

Even minimizing the spacing with which the assemblies are fed to the rolling station, however, the output of the filter assembly machine can only be increased so far without also increasing rolling speed

(and so endangering the integrity of the open ends of the single cigarette portions) .

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a method and filter assembly machine for producing filter-tipped cigarettes, designed to eliminate the above drawbacks, and which at the same time are cheap and easy to implement.

According to the present invention, there are provided a method and filter assembly machine for producing filter-tipped cigarettes, as claimed in the accompanying Claims .

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1, 2 and 3 show, schematically, the production of two filter-tipped cigarettes in accordance with the present invention;

Figure 4 shows a schematic front view, with parts removed for clarity, of an initial portion of a filter assembly machine in accordance with the present invention;

Figure 5 shows a larger- scale , schematic front view of a parting drum of the Figure 4 filter assembly machine ;

Figure 6 shows a schematic front view, with parts removed for clarity, of an intermediate portion of the Figure 4 filter assembly machine; Figure 7 shows a schematic side view, with parts removed for clarity, of a longitudinal band cutting station of the Figure 4 filter assembly machine;

Figure 8 shows a schematic cross section of a parting drum of the Figure 7 longitudinal cutting station;

Figure 9 shows a larger-scale, schematic front view of a transverse band cutting station of the Figure 4 filter assembly machine;

Figures 10 and 11 show larger-scale, schematic views in perspective of a tension adjusting device of the Figure 9 transverse cutting station;

Figure 12 shows a schematic cross section of two cutting drums of the Figure 9 transverse cutting station;

Figure 13 shows a schematic front view, with parts removed for clarity, of a variation of the initial portion of the filter assembly machine.

PREFERRED EMBODIMENTS OF THE INVENTION

Figures 1, 2 and 3 show, schematically, the production of two filter-tipped cigarettes 1 (Fig 3), each comprising a single cigarette portion 2 and a filter 3 joined by a gummed band 4.

As shown in Figure 1, a quadruple cigarette portion 5 (i.e. four times the length of single cigarette portion 2 of filter-tipped cigarette 1) is first cut centrally by a blade 6 into two side by side double cigarette portions 7 (i.e. each twice the length of single cigarette portion 2 of filter-tipped cigarette 1) . Next, the two double cigarette portions 7 are first staggered (by moving one double cigarette portion 7 transversely) so they are positioned a given transverse distance apart, and are then centred axially into alignment with each other (by moving both double cigarette portions 7 axially at the same time) .

As shown in Figure 2, a double filter 8 (i.e. twice the length of filter 3 of filter-tipped cigarette 1) is first cut centrally by a blade 9 into two side by side filters 3. Next, the two filters 3 are parted (by moving both) axially, so they are positioned a given distance apart substantially equal to (but no less than) the length of a double cigarette portion 7. A double cigarette portion 7 is then inserted between the two parted filters 3 to form an assembly 10 comprising two filters 3 separated by a double cigarette portion 7. And, finally, two bands 4 are applied simultaneously to filters 3 and to the ends of double cigarette portion 7 to connect the ends of double cigarette portion 7 to filters 3.

As shown in Figure 3 , once the two bands 4 are applied, assembly 10 is rolled to wind bands 4 simultaneously about filters 3 and double cigarette portion 7. Next, a blade 11 cuts assembly 10 centrally, in the middle of double cigarette portion 7, into two side by side filter-tipped cigarettes 1 (i.e. positioned coaxially, with their facing ends contacting) . And, finally, one filter-tipped cigarette 1 is 'tip-turned' to face the same way as the other filter-tipped cigarette 1, and to convert the two side by side successions of filter-tipped cigarettes 1 to one succession (obviously with half the spacing of the two side by side successions) .

Number 12 in Figure 4 indicates as a whole an initial portion of a filter assembly machine 13 for producing filter-tipped cigarettes 1 as described above and shown in Figures 1-3.

Filter assembly machine 13 receives quadruple cigarette portions 5 from a known cigarette manufacturing machine 14 comprising an output beam 15, along which a continuous cigarette rod (not shown) is fed and cut into a succession of quadruple cigarette portions 5 by a known cutting head . (not shown) . And a feed device 16 (known as a 'spider' ) of filter assembly machine 13 transfers quadruple cigarette portions 5 from output beam 15 of cigarette manufacturing machine 14 to an input drum 17 with peripheral suction seats for quadruple cigarette portions 5.

From input drum 17, quadruple cigarette portions 5 are transferred to a cutting drum 18, which has peripheral suction seats for quadruple cigarette portions 5, and cooperates with blade 6 to cut quadruple cigarette portions 5 transversely into double cigarette portions 7 as described above.

In the Figure 13 variation, cigarette manufacturing machine 14 is a dual-cigarette-rod machine, so quadruple cigarette portions 5 are removed in pairs from their output beams 15 and transferred to input drum 17; and input drum 17 has two sets of suction seats arranged along two side by side, eccentric circles, and which receive the pairs of quadruple cigarette portions 5 from feed device 16, and release quadruple cigarette portions 5 to cutting drum 18.

As shown in Figure 4, double cigarette portions 7 are transferred from cutting drum 18 to a parting drum 19, by which each two initially aligned (coaxial) double cigarette portions 7 are staggered transversely (by moving one double cigarette portion 7 transversely) into a position a given transverse distance apart. As shown more clearly in Figure 5, parting drum 19 picks up double cigarette portions 7 from an input station 20 at cutting drum 18, and feeds them to an output station 21 at a follow-up transfer drum 22. Parting drum 19 has two groups 23 of suction seats 24 for double cigarette portions 7, which groups 23 are arranged along two side by side, eccentric circles with the same radius (i.e. two circles with non-coincident central axes of symmetry) , so the paths PI and P2 of the two groups 23 of suction seats 24 overlap at two points coincident with input station 20 and output station 21.

As shown clearly in Figure 5, the angular distance travelled by seats 24 of a first group 23a to transfer double cigarette portions 7 from input station 20 to output station 21 along path PI is shorter than the angular distance travelled by seats 24 of a second group 23b to transfer double cigarette portions 7 from input station 20 to output station 21 along path P2. The two groups 23 of seats 24 being carried by the same parting drum 19 and therefore angularly integral with each other and travelling at the same angular speed, the above di f ference in angula r di stance el ays ' the double cigarette portions 7 in the seats in second group 23b with respect to those in the seats in first group 23a, thus transversely staggering double cigarette portions 7. In other words, to stagger each two double cigarette portions 7, a first double cigarette portion 7 is fed from input station 20 to output station 21 along path PI, and a second double cigarette portion 7 is fed, at the same speed as the first double cigarette portion 7, from input station 20 to output station 21 along path P2 longer than path PI .

As shown in Figure 4, the double cigarette portions 7 staggered transversely by parting drum 19 are transferred at output station 21 to transfer drum 22, which has peripheral suction seats for double cigarette portions 7, and transfers the transversely staggered double cigarette portions 7 to a centring drum 25 with peripheral suction seats for double cigarette portions 7. The peripheral suction seats of centring drum 25 are movable axially (i.e. parallel to the axis of rotation of centring drum 25) by a cam actuating system to centre double cigarette portions 7 axially (by moving both double cigarette portions 7 axially at the same time) . In other words, double cigarette portions 7 are fed onto centring drum 25 axially misaligned, and are fed off centring drum 25 axially aligned. By way of example, centring drum 25 is of the type described in Patent US4531629A1 or US4200179A1. A mass of double filters 8 is housed in a hopper 26 with a bottom outlet connected to a pickup drum 27, which has peripheral suction seats for double filters 8 and cooperates with blade 9 to cut double filters 8 transversely into filters 3 as described above.

Filters 3 are transferred from pickup drum 27 to a transfer drum 28 with peripheral suction seats for filters 3.

From transfer drum 28, filters 3 are transferred to a parting drum 29 with peripheral suction seats for filters 3.

The peripheral suction seats of parting drum 29 are movable axially (i.e. parallel to the axis of rotation of parting drum 29) by a cam actuating system to axially part filters 3 (by moving both filters 3 axially at the same time) . In other words, filters 3 are fed onto parting drum 29 axially side by side, and are fed off parting drum 29 axially parted. By way of example, parting drum 29 is of the type described in Patent US4531629A1 or US4200179A1.

In a known variation not described here in detail, there is no cam actuating system, the seats are fixed, and filters 3 are parted along the seats by a pneumatic parting system.

At an input station 31, the axially parted filters 3 are transferred from parting drum 29 to a combining drum 30 with peripheral suction seats for filters 3 and double cigarette portions 7. And, at a further input station 32 downstream from input station 31, centring drum 25 feeds double cigarette portions 7 into the seats on combining drum 30 containing filters 3, to form assemblies 10.

Number 33 in Figure 6 indicates as a whole an intermediate portion of filter assembly machine 13.

As shown in Figure 6, assemblies 10 are transferred from combining drum 30 to a connecting drum 34 with peripheral suction seats for assemblies 10; and, at a feed station 35, two gummed bands 4, supplied by a feed unit 36, are applied to the assembly 10 in each seat on connecting drum 34. As stated, each band 4 connects a filter 3 integrally to a corresponding double cigarette portion 7, and is just- slightly longer than the circumference of assembly 10.

Assemblies 10 with bands 4 are transferred from combining drum 30 to a rolling drum 37, on which bands

4 are wound fully about assemblies 10, and which, for example, is of the type described in Patent US5349968A1.

Filter assembly machine 13 also comprises a known end portion (not shown) comprising a cutting drum, on which blade 11 (Figure 3) cuts each assembly 10 in half, in the middle of double cigarette portion 7, into two side by side filter-tipped cigarettes 1 (i.e. positioned coaxially, with their facing ends contacting) . The end portion of filter assembly machine 13 also comprised a tip- turning' drum, on which one succession of filter-tipped cigarettes 1 is ^x tip- turned' to convert the two side by side successions of filter-tipped cigarettes 1 to one succession (obviously with half the spacing of the two side by side successions) . By way of example, the tip- turning drum is of the type described in Patent US4090602A1. The end portion of filter assembly machine 13 also comprises an output conveyor for carrying filter-tipped cigarettes 1 off filter assembly machine 13.

As shown in Figure 6, feed unit 36 comprises an unwinding station 38 where a double-width strip 39 (i.e. twice the width of bands 4) is unwound off a reel 40; a longitudinal cutting station 41 where double- width strip 39 is cut longitudinally into two single- width strips 42 (i.e. of the same width as bands 4); and a transverse cutting station 43 where the two single-width strips 42 are cut transversely into bands 4, which are then applied to assemblies 10 on connecting drum 34. Longitudinal cutting station 41 comprises a centring drum 44 for positioning double-width strip 39 to ensure a precise longitudinal cut; and a cutting drum 45, which cooperates with a rotary blade 46 positioned alongside cutting drum 45 to continuously cut double-width strip 39 longitudinally. A preferred embodiment has two pressure drums 47, which press double-width strip 39 onto the periphery of cutting drum 45 upstream from rotary blade 46, to position double-width strip 39 correctly as it is being cut. The two pressure drums 47 are fitted side by side on a support 48, which is pushed against cutting drum 45 by an elastic member 49 (typically a spring) to push pressure drums 47 elastically against cutting drum 45 and hold double-width strip 39 firmly on the periphery of cutting drum 45.

Directly downstream from cutting station 41, a rotary parting device 50 parts the two single-width strips 42 transversely, so they are positioned a given distance apart, i.e. the two single-width strips 42 are wound about and gradually parted transversely by rotary parting device 50.

As shown in Figure 8, parting device 50 comprises a fixed shared central supporting body 51 integral with a frame of filter assembly machine 13; and two side by side lateral drums 52 fitted to supporting body 51 to rotate respectively about two axes of rotation 53 inclined at equal opposite angles with respect to the horizontal. In a preferred embodiment, each lateral drum 52 has a shoulder 56 defining a supporting surface for supporting and defining the transverse position of the corresponding single-width strip 42. Being inclined at equal opposite angles, the two lateral drums 52 transversely divert and so transversely part the two single-width strips 42 as they wind about lateral drums 52.

As shown in Figure 6, a gumming device 57 between longitudinal cutting station 41 and transverse cutting station 43 applies a film of glue to the top face of both single-width strips 42, which are fed through gumming device 57 parallel to each other and a given distance apart.

As shown in Figure 9, transverse cutting station 43 comprises a cutting device 58, which, at each cycle, scissor-cuts both single-width strips 42 to cut off two bands 4, which are applied to the same assembly 10 on connecting drum 34. Cutting device 58 comprises a cutting drum 59 with a number of peripheral suction seats 60, each of which is designed to retain two side by side bands 4 by suction, and has a counterblade 61. In the preferred embodiment in Figure 9, each counterblade 61 is defined by a contoured cavity formed in the outer periphery of cutting drum 59 (i.e. counterblade 61 is Mug' into as opposed to projecting from cutting drum 59) . Cutting device 58 also comprises a cutting drum 62 mounted to rotate alongside cutting drum 59 and supporting a number of blades 63, each of which projects from the outer periphery of cutting drum 62, and cooperates with a corresponding counterblade 61 on cutting drum 59 to scissor-cut two bands 4 at a time off single-width strips 42.

In one embodiment, blades 63 and counterblades 61 each comprise two separate bodies spaced apart at the two single-width strips 42. In an alternative embodiment, blades 63 and counterblades 61 each comprise one elongated body covering both single-width strips 42. Each blade 63 and corresponding counterblade 61 are inclined slightly (i.e. ^' 'skewed') with respect to each other to scissor-cut a single-width strip 42 in between them.

Transverse cutting station 43 also comprises a tension adjusting device 64 with a diverting member 65, which, by diverting and restoring the path of each single-width strip 42, cyclically adjusts the tension of single-width strip 42 between a taut condition and a slack condition. Tension adjusting device 64 is indispensable for ensuring a good-quality scissor-cut, and in particular for preventing that the separation of the side bands 4 from the single-width strip 42 ends by tearing instead of scissor-cutting .

As shown more clearly in Figures 10 and 11, for each single-width strip 42, diverting member 64 comprises a cam 66, which acts directly on single-width strip 42 and is fitted to a common pin 67 mounted to rotate about an axis 68. When the common pin (supporting both cams 66) rotates about axis 68, each cam 66 rotates cyclically back and forth between a maximum tension position (i.e. taut condition) and a minimum tension position (i.e. slack condition). By way of example, cutting device 58 is of the type described in Patent US4943341A1 or EP1097894B1.

As stated, blades 63 and counterblades 61 perform a scissor cut, i.e. a cut which, as opposed to instantly cutting the whole width, advances gradually across each single-width strip 42. The two single-width strips 42 being located a given distance apart, one is obviously cut with a certain delay with respect to the other, and which equals the distance between the two single-width strips 42 divided by the speed at which the scissor cut is made. To allow for this delay (i.e. time difference) in scissor-cutting the two single- width strips 42, one cam 66 is offset angularly with respect to the other, so that the variation in tension induced by each cam 66 is always perfectly synchronized with scissor-cutting the corresponding single-width strip 42.

Filter assembly machine 13 described has numerous advantages .

In particular, as they are rolled on rolling drum 37 of filter assembly machine 13, the ends of double cigarette portions 7, as opposed to facing outwards (i.e. being exposed, with the risk of tobacco fallout) as on conventional filter assembly machines, are ^plugged' by filters 3, thus excluding any possibly of tobacco fallout from the ends. On filter assembly machine 13 described, rolling speed may therefore be increased considerably to achieve very high output rates with no risk of tobacco fallout from the ends of double cigarette portions 7.

Moreover, filter assembly machine 13 described is cheap and easy to produce, by being very similar in design and component parts to a conventional filter assembly machine, from which it differs solely by making different use of certain components.