WO2011036452A1

WO2011036452A1 - Tow cutter

Info

Publication number: WO2011036452A1
Application number: PCT/GB2010/001788
Authority: WO
Inventors: Graham Penrose
Original assignee: Filtrona International Limited
Priority date: 2009-09-23
Filing date: 2010-09-22
Publication date: 2011-03-31
Also published as: PL2480100T3; CN102573533B; EP2480100A1; KR20120071390A; EP2480100B1; CN102573533A; KR101853778B1; MY174700A; LT2480100T; KR20180000349A; WO2011036451A1

Abstract

An in-line apparatus for continuously cutting filamentary tow into fibres, the apparatus comprising: a first tow inlet feeder including a first tow inlet ledger (56a) for feeding a first stream of filamentary tow (2a) through the first tow inlet ledger (56a); a first fibre outlet ledger (58a) arranged in line with and spaced downstream of the first tow inlet ledger (56a); a second tow inlet feeder including a second tow inlet ledger (56b) for feeding a second stream of filamentary tow (2b) through the second tow inlet ledger (56a); a second fibre outlet ledger (58b) arranged in line with and spaced downstream of the second tow inlet ledger (56b); at least one knife blade (60) arranged to cut the streams into a flow of cut fibres from the first and second streams of filamentary tow; and at least one cut fibre exit gas jet (64) arranged for carrying the resulting flow of cut fibres from the first and second streams of filamentary tow away from the knife blade (60) and through first and second outlet ledgers; the apparatus being arranged to substantially alternate the flows of cut fibres from the first and second streams and merge them into a single product flow.

Description

TOW CUTTER

The present invention relates to the cutting of filamentary tow into short, e.g. staple, fibres, e.g. for subsequent formation into tobacco smoke filter rods.

UK Specification No. 1 ,221 ,346 describes a process for the production of filter rods of staple fibre in which a band of tow incorporating a bonding agent is fed continuously by a stuffer jet to a rotary cutter, a fan downstream of the cutter drawing the fibres away from the cutter in an airstream perpendicular to the tow feed path and then impelling the fibres in the airstream parallel to the tow feed path to a unit where the fibres are separated from the airstream and condensed to rod form for filter production. This is a commercial process, but its rate of throughput is not as high as is desirable, and various attempts to increase the rate of operation have led to undesirable lack of uniformity in the cut fibre length and/or in the distribution of the fibres in the rod product.

There is a need for an apparatus which can produce filter rods from tow cut into short, e.g. staple, fibres at increased speed, for example speeds in excess of 200 to 250 m/min. The present invention provides in-line apparatus for continuously cutting filamentary tow into fibres (and, optionally, condensing the cut fibres to rod form), the apparatus comprising:

a first tow inlet feeder including a first tow inlet ledger for feeding (e.g. advancing) a first stream of filamentary tow through the first tow inlet ledger (to a knife blade);

a first fibre outlet ledger arranged in line with and spaced downstream of the first tow inlet ledger;

a second tow inlet feeder including a second tow inlet ledger for feeding (e.g.

advancing) a second stream of filamentary tow through the second tow inlet ledger (to a knife blade);

a second fibre outlet ledger arranged in line with and spaced downstream of the second tow inlet ledger;

at least one knife blade arranged (e.g. rotatably mounted) for periodic passage (e.g. once per rotation) between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow and cut the streams into a flow of cut fibres from the first stream of filamentary tow and a flow of cut fibres from the second stream of filamentary tow (respectively); and at least one cut fibre exit gas (e.g. air) jet arranged in line with the tow inlet ledgers for carrying the resulting flow of cut fibres from the first stream of filamentary tow and flow of cut fibres from the second stream of filamentary tow away from the knife blade and through the first and second outlet ledgers (respectively);

the apparatus being arranged to substantially alternate the flows of cut fibres from the first and second streams of filamentary tow and merge them into a single product flow of cut fibres.

Preferably the knife blade (or blades) are rotatably mounted so the (or each) blade passes between each inlet and outlet ledger once per rotation.

The apparatus may include one or more knife blade(s), for example 2 to 30 knife blades, for example 2 to 12 knife blades, for example 2, 3, 4, 5, 6, 12 or 24 knife blade(s) arranged (e.g rotatably mounted) for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow and cut the streams into a flow of cut fibres from the first stream of filamentary tow and a flow of cut fibres from the second stream of filamentary tow (respectively).

The applicants have found that apparatus according to the invention, which may cut fibres from two (or more) streams of filamentary tow and merge (combine) these into a single product flow of cut fibres, may allow production of filter rods from tow cut into short, e.g. staple, fibres at improved speeds, while maintaining the desired uniformity in the cut fibre length and/or in the distribution of the fibres in the rod product. In one example, the knife blade (or blades) is (are) arranged (e.g. rotatably mounted) for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one at a time (e.g. one after the other) and thereby cut the first and second streams into substantially alternating flows of cut fibres from the first and second tow streams.

Accordingly, an example of the present invention provides in-line apparatus for continuously cutting filamentary tow into cut fibres (and, optionally, condensing the cut fibres to rod form), the apparatus comprising:

a first tow inlet feeder including a first tow inlet ledger for feeding (e.g. advancing) a first stream of filamentary tow through the first tow inlet ledger (to a knife blade); a first fibre outlet ledger arranged in line with and spaced downstream of the first tow inlet ledger;

a second tow inlet feeder including a second tow inlet ledger for feeding (e.g.

at least one knife blade arranged (e.g. rotatably mounted) for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one (stream) at a time (e.g. one stream after the other) and thereby cut the streams into substantially alternating flows of cut fibres from the first and second tow streams (respectively), and

at least one cut fibre exit gas (e.g. air) jet arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres.

Preferably the knife blade (or blades) are rotatably mounted so the (or each) blade passes between each (first, second) inlet and outlet ledger once per rotation (to intersect the relevant passing streams of filamentary tow and thereby cut it into a flow of cut fibres).

In an example, the knife blade (or blades) may be arranged (e.g. rotatably mounted) so that while the or any blade passes between the first tow inlet and first fibre outlet ledger to intersect the passing first stream of filamentary tow and cut the stream into a flow of cut fibres from the first tow stream, there is not a knife blade between the second tow inlet and second fibre outlet ledger; and while the (or any) knife blade passes between the second tow inlet and second fibre outlet ledger to intersect the second stream of filamentary tow and cut the stream into a flow of cut fibres from the second tow stream there is not a knife blade between the first tow inlet and first fibre outlet ledger, thereby cutting the first and second streams of tow one at a time (and/or one stream after the other) into substantially alternating flows of cut fibres from the first and second tow streams. Examples are described below but other arrangements according to the invention (e.g. variation of number and spacing of knife blades; speed of cutting; speed of tow stream etc.) would be readily appreciated by the skilled man. In this example, the apparatus may include one or more knife blade(s), for example 2 to 30 knife blades, for example 2 to 12 knife blades, for example 2, 3, 4, 5, 6, 12 or 24 knife blade(s), rotatably mounted for periodic passage between the tow inlet and fibre outlet ledgers to intersect tow passing therepast and cut it into fibres, as long as the apparatus (knife blades) are arranged for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one at a time one at a time (and/or one stream after the other) and thereby cut the streams into substantially alternating flows of cut fibres from the first and second tow streams. The applicants have found that if a single stream of filamentary tow is fed through a single inlet ledger for cutting into fibres the speed at which the tow may be fed to the cutting blade (through the inlet ledger) may be limited. Without being bound by theory it is believed that this is because the passage of the knife blade between the inlet and outlet ledgers restricts the flow of air between the inlet and outlet ledgers, thereby disrupting the flow of air (e.g. due to the cut fibre exit jet) which removes cut fibres away from the knife blade. In other words, the speed at which the tow is feed to the knife must be restricted to ensure there is sufficient time to transport (carry away) the fibres which have been cut by the knife, before the next batch of fibres are cut from the continuously advancing stream of filamentary tow by the next knife pass. The applicants have found that a knife blade (or blades) arranged (e.g. rotatably mounted) for periodic passage to intersect first and second streams of filamentary tow one stream at a time (and/or one stream after the other) - i.e. in such a way that when the first stream of tow is being cut the second is not, and vice verse - provides substantially alternating flows of cut fibres from the first and second streams of tow, for subsequent combination into a single product stream of cut fibres. This allows the total amount of tow being fed to the knife blade(s) to be markedly increased [because there are two (or more) streams] without increasing either the knife blade (cutter) speed or the inlet speed of the (each) stream(s) of tow; while maintaining the desired uniformity in the cut fibre length and/or in the distribution of the fibres in the resulting rod product (which is formed from the single product stream of cut fibres).

The cut fibre exit gas (e.g. air) jet [which is arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres] may include a single funnel (e.g. a venturi funnel) downstream of the first and second fibre outlet ledgers. The single funnel may merge the substantially alternating flows of cut fibres (from the first and second tow streams) from the first and second outlet ledgers.

The apparatus may further comprise a unit for separating air from the product flow of cut fibres and condensing the latter to rod form, for example including an air permeable frusto-conical screen. The air permeable frusto-conical screen may taper inward, longitudinally, from a wider inlet to a narrower outlet. The streams of air and cut fibres (e.g. the single product flow of cut fibres) pass into the air permeable frusto-conical screen, where they proceed (longitudinally) from screen inlet to outlet. Air is separated from the fibres by escaping through the tapering air permeable frusto-conical screen (e.g. through the tapering air permeable e.g. mesh walls), and the cut fibres exit the screen outlet for condensation to rod form. The screen may be a screen formed of a mesh (e.g. a wire mesh), for example having openings of size 0.088 mm to 0.841 mm (mesh size 170 to mesh size 20), for example 0.125 mm to 0.354mm (mesh size 120 to mesh size 45), for example 0.210 mm to 0.297 mm (mesh size 70 to mesh size 50), for example 0.250 mm (mesh size 60). Preferably the unit for separating air from the cut fibres and condensing the latter to rod form (which, for example, may includes the air permeable frusto-conical screen formed of a mesh having openings of size 0.088 mm to 0.841 mm) is attached directly to the outlet of the fibre exit gas jet (or the outlets of each fibre exit jet, if more than one jet is present). In one example, the air permeable frusto-conical screen is formed of a mesh of mesh size 100 (having openings of size 0.148 mm). The air permeable frusto- conical screen may be formed of a mesh of mesh size 60 (having openings of size 0.25 mm), 70 (having openings of size 0.21 mm) or 80 (having openings of size 0.17 mm) etc.. In another example, the cut fibre exit gas (e.g. air) jet [which is arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres] may include a first funnel (e.g. a venturi funnel) downstream of the first fibre outlet ledger, and a second funnel (e.g. a venturi funnel) downstream of the second fibre outlet ledger. The first and second funnels provide (alternating) first and second streams of cut fibres from the first and second outlet ledgers, respectively. In this example, the unit for separating air from the cut fibres and condensing the latter to rod form (if present) may (also) merge the resulting substantially alternating flows of cut fibres from the first and second tow streams from the first and second funnels into a single product flow of cut fibres, e.g. during and/or immediately prior to condensing the product flow of cut fibres to rod form.

The first and second streams of filamentary tow may be from first and second sources (e.g. bales) of tow, which may be the same or different. In another example, the first and second streams of tow are from the same source (e.g. bale) of tow, which is split into first and second streams prior to feeding to the knife blade.

Accordingly, another example of the present invention provides in-line apparatus for continuously cutting filamentary tow into fibres and condensing the cut fibres to rod form, the apparatus comprising:

a second tow inlet feeder including a second tow inlet ledger for feeding (e.g.

at least one knife blade arranged (e.g. rotatably mounted) for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one at a time (e.g. one after the other) and thereby cut the streams into substantially alternating flows of cut fibres from the first and second tow streams (respectively);

at least one cut fibre exit gas (e.g. air) jet arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres; and a unit for separating air from the product flow of cut fibres and condensing the latter to rod form.

The unit for separating air from the product flow of cut fibres and condensing the latter to rod form may include an air permeable frusto-conical screen. The air permeable frusto-conical screen may taper inward, longitudinally, from a wider inlet to a narrower outlet. The stream(s) of air and cut fibres (e.g. the single product flow of cut fibres or the substantially alternating flows of cut fibres from the first and second tow streams) are carried into the air permeable frusto-conical screen, where they proceed (longitudinally) from screen inlet to outlet. Air is separated from the fibres by escaping through the tapering air permeable frusto-conical screen (e.g. through the tapering air permeable e.g. mesh walls), and the cut fibres exit the screen outlet for condensation to rod form. The screen may be a screen formed of a mesh (e.g. a wire mesh), for example having openings of size 0.088 mm to 0.841 mm (mesh size 1 0 to mesh size 20), for example 0.125 mm to 0.354mm (mesh size 120 to mesh size 45), for example 0.210 mm to 0.297 mm (mesh size 70 to mesh size 50), for example 0.250 mm (mesh size 60). . Preferably the unit for separating air from the cut fibres and condensing the latter to rod form (which, for example, may includes the air permeable frusto-conical screen formed of a mesh having openings of size 0.088 mm to 0.841 mm ) is attached directly to the outlet of the fibre exit gas jet (or the outlets of each fibre exit jet, if more than one jet is present). In one example, the air permeable frusto-conical screen is formed of a mesh of mesh size 100 (having openings of size 0.148 mm). The air permeable frusto-conical screen may be formed of a mesh of mesh size 60 (having openings of size 0.25 mm), 70 (having openings of size 0.21 mm) or 80 (having openings of size 0.1 mm) etc..

In examples of the invention, the tow inlet (upstream) ledger(s) may be annular with the material (filamentary tow) path extending therethrough. The fibre outlet (downstream) ledger(s) may be annular with the material (cut fibre) path extending therethrough. Any tow feed to the tow inlet ledger(s) may be used, but a stuffer jet or jets may be preferred. The apparatus may comprise further (e.g. a third, fourth etc.) tow inlet feeder(s), each including a further tow inlet ledger [e.g. for feeding (e.g. advancing) a further stream of filamentary tow through the further tow inlet ledger (to a knife blade)]; and corresponding further fibre outlet ledger(s) arranged in line with and spaced downstream of the further tow inlet ledger (s). These may be used with a single funnel as described above, which collects cut fibres from all outlet ledgers; or with a further funnel(s) [e.g. venturi funnel(s)] for each further outlet ledgers (as also described above). Thus the apparatus may be adapted for use with three or more tow streams. It will be appreciated that when used with three or more tow streams the apparatus is arranged to substantially alternate the resulting flows of cut fibres from the three streams one at a time and one after the other and and merge the substantially alternating flows of cut fibres (e.g. flow of fibres from the first stream (of tow), then flow from the second stream, then flow from the third stream, then the next flow of fibres from the first stream, then the next flow from the second stream and so on) into a single product flow of cut fibres. The (or each) knife blade rotatably mounted for periodic passage between

(adjacent) tow inlet and fibre outlet ledgers to intersect tow passing therepast and cut it into fibres may include one or more venting holes. The venting holes allow passage of gas (air) through the (or each) knife blade in the direction in which the tow is travelling, which may enable a further increase in production line speeds. The venting holes may be 1 to 5 mm in diameter. The or each knife blade (e.g. a knife blade including one or more venting holes) may having a cutting edge of profile angle 15 to 50 degrees, and/or cutting edge is of width 15mm to 57mm. Preferably, the cutting edge has a profile angle (also referred to as cutting angle) of 20 to 48 degrees, for example 32 degrees or 45 degrees). The cutting edge may be straight (i.e. present a straight edge to the tow passing therepast as it cuts) or curved (i.e. present a curved edge of to the tow passing therepast as it cuts). The knife blade may be of thickness (in the direction the tow is passing), 0.1 to 0.23 mm, preferably 015mm (6 thousands of an inch) or 0.2 mm (8 thousands of an inch). The applicants have found that providing a knife blade of the defined profile angle (and/or width) allows increased air flow through the cutter, thereby allowing increased machine speed while maintaining cut fibre (staple fibre) length, and without unduly increasing PD variation in the resulting rod formed from the cut fibres. In other words, the applicants have found that the defined knife blade is of a shape that minimizes disruption of air through the ledgers, yet provides an efficient cutting operation.

The apparatus may include a ventilator for one (or each) ledger. The ventilator(s) allow increased air flow through the cutter, and may allow increased machine speed while maintaining cut fibre (staple fibre) length and PD variation in the resulting rod formed from the cut fibres.

In another example of an apparatus according to the invention the knife blade (or blades) may be arranged (e.g. rotatably mounted) for periodic passage (e.g. once per rotation) between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow and cut the streams into a flow of cut fibres from the first stream of filamentary tow and a flow of cut fibres from the second stream of filamentary tow at substantially the same time (e.g. with a first blade cutting the first tow stream and the blade cutting the second tow stream, e.g. substantially simultaneously). In this example the apparatus is arranged to control the flows of cut fibres from the first and second streams of filamentary tow and merge them into a single product flow of cut fibres, for example by (e.g. using a controller for) adjusting the speed of flow and/or the flow path length of the first and/or second flows of cut fibres to a (product flow) combiner such that the flows of cut fibres from the first and second streams of filamentary tow arrive at the flow combiner substantially alternately for merging into the single product flow of cut fibres. The invention also provides an in-line method of (e.g. continuously) cutting filamentary tow into fibres (and, optionally, condensing the cut fibres to rod form), the method comprising: feeding first and second streams of filamentary tow to a rotary knife blade whose rotary path periodically intersects the paths of the tow streams one at a time (and/or one after the other) and thereby cuts the streams into substantially alternating flows of cut fibres from the first and second tow streams; carrying, by means of an exit gas (e.g. air) jet acting in-line with the tow feeds, the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade; and merging the substantially alternating flows of cut fibres from the first and second tow streams into a single product flow of cut fibres. The method may include a further step of separating air from the (product flow of) cut fibres and condensing the latter to rod form [for example, by passing the fibres through an air permeable frusto-conical screen (e.g. formed of a mesh having openings of size 0.088 mm to 0.841 mm (mesh size 170 to mesh size 20), for example 0.125 mm to 0.354mm (mesh size 120 to mesh size 45), for example 0.210 mm to 0.297 mm (mesh size 70 to mesh size 50), for example 0.250 mm (mesh size 60). ) thereby separating air from the cut fibres; and condensing the cut fibres to rod form].

The first and second streams of tow may be from first and second sources (e.g. bales) of tow, which may be the same or different. In another embodiment, the first and second streams of tow may be from the same source (e.g. bale) of tow, which is split into first and second streams prior to feeding to the knife blade.

The exit gas (e.g. air) jet [which carries the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade] may, for example, include a single funnel (e.g. a venturi funnel) downstream of the first and second streams of filamentary tow. The single funnel may merge the cut fibres from the first and second streams of filamentary tow into a single product flow of cut fibres.

In another example, the cut fibre exit gas (e.g. air) jet [which carries the resulting substantially altemating flows of cut fibres from the first and second tow streams away from the knife blade] may include a first funnel (e.g. a venturi funnel) and a second funnel (e.g. a venturi funnel) for the cut fibres from the first and second tow streams, respectively. In this example, merging the substantially alternating flows of cut fibres from the first and second tow streams from the first and second funnels into a single product flow of cut fibres may take place during a step of separating air from the cut fibres from the first and second tow streams and condensing the latter to rod form [for example, by passing the fibres through an air permeable frusto-conical screen (e.g. formed of a mesh having openings of size 0.088 mm to 0.841 mm (mesh size 170 to mesh size 20), for example 0.125 mm to

0.354mm (mesh size 120 to mesh size 45), for example 0.210 mm to 0.297 mm (mesh size 70 to mesh size 50), for example 0.250 mm (mesh size 60). ) thereby separating air from the cut fibres; and condensing the cut fibres to rod form]. In other words merging the substantially alternating flows of cut fibres from the first and second tow streams from the first and second funnels into a single product flow of cut fibres may take place immediately prior to and/or during the step of separating air from the cut fibres (from the first and second tow streams) and condensing the fibres to rod form. A wholly in-line path is thus provided for the passage of the first and second streams of tow to the cutter, and of the cut fibres therefrom (e.g. to a unit for separating air from the cut fibres and condensing the latter to rod form). The unit may be attached directly to the outlet of the fibre exit jet, thus permitting minimum travel of the cut fibres prior to rod formation.

The present invention may therefore provide in-line apparatus for continuously cutting filamentary tow into fibres and, optionally, condensing the cut fibres to (e.g. continuously issuing) rod form, and/or in-line apparatus for continuously cutting filamentary tow into fibres (and e.g. delivering the cut fibres in a continuous stream), which may, for example, deliver the cut fibres to a unit for separating air from the cut fibres and condensing the latter to (e.g. continuously issuing) rod form. The invention also provides in-line method(s) of continuously cutting filamentary tow into fibres and condensing the cut fibres to (e.g. continuously issuing) rod form. The continuously issuing rod (of filtering material, formed from the cut fibres e.g. by methods or using apparatus of the invention) may be cut into individual filter or filter elements for subsequent use. More usually, however, the continuously issuing rod (of filtering material, formed from the cut fibres e.g. by methods or using apparatus of the invention) is first cut into double or higher multiple (usually quadruple or sextuple) filter or filter element rod lengths for subsequent use. When the initial cut is into quadruple or higher rod lengths, the multiple lengths are subsequently cut into double lengths for further cigarette or filter assembly. If the filter is for direct application to a cigarette, the multiple rod lengths are subsequently cut into double rod lengths and the double length filter rod is assembled and joined (e.g. by ring tipping or full tipping overwrap) between a pair of wrapped tobacco rods with the combination being severed centrally to give two individual cigarettes, as is well known in the art. The present invention includes double and higher multiple (length) filter rods and/or filter element rods.

Thus, according to the present invention in a further aspect there is provided a double or higher multiple length filter or filter element comprising a filter rod produced (e.g. formed from cut fibres) according to the method or methods described above and claimed herein, or produced (formed) using apparatus (or apparatuses) described above and claimed herein.

According to the invention in a still further aspect there is provided a method of manufacture of a smoking article (e.g. a filter cigarette) comprising a step of applying (e.g. joining) a tobacco smoke filter comprising a filter rod produced (e.g. formed from cut fibres) by a method and/or apparatus of the invention [or a filter including a filter element comprising a filter rod produced (e.g. formed from cut fibres) by a method and/or apparatus of the invention) to a wrapped rod of smoking material (e.g. tobacco). The filter may be a single filter, or, preferably, a filter which forms part of a multiple length filter rod (e.g. a multiple rod of 2, 4, or 6 filters in end-to-end relationship).

In a filter cigarette according to the invention, a filter (e.g. filter rod) made by the method and/or apparatus of the invention (or a filter which includes filter element (e.g. filter rod) made by a method and/or apparatus according to the invention) is joined to a wrapped tobacco rod with one end towards the tobacco.

The filter or filter element comprising a filter rod produced (e.g. formed from cut fibres) may, for example, be joined to the wrapped tobacco rod by ring tipping (which engages around just the adjacent ends of a (wrapped) filter and rod to leave much of the filter wrapper exposed) or by a full tipping overwrap (which engages around the full filter length and adjacent end of the tobacco rod). Any filter or filter cigarette according to the invention may be unventilated, or may be ventilated by methods well known in the art, e.g. by use of a pre-perforated or air-permeable plugwrap and/or laser perforation of plugwrap and tipping overwrap. The invention is illustrated, by way of example only, by the accompanying drawings, in which: Figure 1 is a diagrammatic elevation view of a complete filter rod production apparatus according to the invention; Figure 2 is a similar enlarged view of the air separation and rod formation portion of the apparatus of Figure 1 ;

Figure 3 is a diagrammatic side elevation view, partly in section, of an example tow cutting device according to the invention suitable for use in the Figure 1 and Figure 2 apparatus and method; and

Figure 4 is a diagrammatic side elevation view, partly in section, of another example tow cutting device according to the invention suitable for use in the Figure 1 and Figure 2 apparatus and method;

In the illustrated filter rod production methods and apparatuses described below, the rod is made from cellulose acetate continuous filamentary tow plasticised with glyceryl triacetate; this is the preferred material for cigarette filter production, but a variety of other materials can be used.

A first stream of filamentary tow 2a and a second stream of filamentary tow 2b are processed, by means well known in the art (e.g. a double track tow processor). Referring to the drawings, from a first bale 1a of continuous filamentary cellulose acetate tow, the tow 2a is drawn upwardly first through an air banding jet 4a, thence over a cylindrical guide 5a, traction being given by rollers 3a. The tow 2a then passes to rollers 6a which rotate faster than rollers 3a and thereby stretch the tow between them and rollers 3a. A further air banding jet 7a forms the tow into a band which form it retains as it passes into box 10a where it is sprayed over the whole of its width with glyceryl triacetate in known manner. The resulting first stream of filamentary tow 2a which has been plasticised is then fed to a cutter device 13, as described below. A second stream of filamentary tow 2b is drawn from a second bale (not shown) and processed similarly using a further banding jet, cylindrical guide, rollers and plasticiser box (also not shown). The resulting second stream of filamentary tow 2b which has been plasticised is then fed to the cutter device 13, as described below. Rollers (not shown) hold the tow streams 2a, 2b in band form until they enter the cutting device 13 according to the invention. A rotary knife cutter within the cutting device is driven by a belt, not shown, which is driven, via an infinitely variable gear, from the main- shaft of a plug-maker 20, as are rollers 3a, 6a etc. via other such gears. By varying the relative rates of rotation of the cutter and the rollers the length of the fibres may be varied. By varying the relative rates of rotation of the rollers 3a, 6a the weight per unit length of the rod may be varied e.g. by varying the rate of rotation of rollers 3a relatively to rollers 6a, the percentage crimp of the filaments of tow 2a entering the cutting device 13 is altered.

Separate examples of the cutting device 13 are described hereinbelow with reference to Figs. 3 and 4. As described below, device 13 provides a combined delivery stream of air and cut fibres.

The combined delivery stream of air and cut fibres (e.g. a single product flow of cut fibres from cutting device 13 such as that described with reference to Fig 3, or e.g. a flow of cut fibres from a cutting device such as that described below with reference to Fig 4) passes through exit 18 into a unit where the fibres are separated from the airstream and condensed to rod form (for filter production). The unit includes an air permeable, e.g.

perforate, frusto-conical screen 21. The screen 21 has an inlet (e.g. which may be connected directly to exit 18) and an outlet, the inlet being of wider diameter than the outlet, and walls made of the air permeable, e.g. perforate, material (e.g. wire mesh). The screen 21 is a 60 mesh screen, having openings of size 0.250 mm. Most of the air escapes through the openings in the wall of screen 21; however, the frusto-conical form ensures that the velocity of the air inside the cone is not unduly reduced by passage of air through its walls. The remainder of the air (passing through the screen outlet) deposits the fibres on a tape 22 and then passes out of holes in a surrounding heating block 24. The latter has a bore 25 through which the tape 22 passes. The bore has a cross section

corresponding to the cross section desired in the rod, e.g. it is circular. It holds the tape 22 so as to envelop the staple fibres in the rod 31. The heating block 24 is of substantial metallic construction so that the tape is held around the fibres in a constant configuration. It is preferred that the fibres remain in suspension until they meet the tape 22. However, it is undesirable that an excessive air flow be used for this purpose as fibres may be blown into the atmosphere instead of being deposited. The rate of flow may be increased by blocking off a part of the screen 21 next to the exit 18.

The tape which is driven by drum 26 and is trained about tension rollers 27 and 28 and guide rollers 29 and 30, carries the fibres now held in the form of the rod 31 through the heating block 24, wherein they are heated by steam coming from a source (not shown) via pipe 33. A plenum chamber within the heating block 24 serves to distribute the steam evenly around the whole of the periphery of the tape enclosing the fibres. Upon passing from the heating block the tape, containing the rod formed from the fibres, passes through cooling enclosure 36 where it is cooled by air supplied to pipe 37. The latter connects with channels inside the cooling enclosure which distribute the air about the tape enclosing the rod, thereby cooling and hardening it so that at the exit of the cooling enclosure a firm rod is delivered. The tape 22, folding from the circular to the flat form, is separated from the rod as it passes on to the drum 26. The continuous rod 31 may pass to a cut-off 42 in which it is cut into equal length rods which are deposited upon a delivery band 35, or first to a wrapping garniture where the fibrous rod is wrapped with a paper wrapper in known manner and thence to the cut-off.

If the edges of the tape 22 as they envelop the fibrous material do not meet perfectly, fibres press between them and form a ridge. To eliminate this a ridge remover 41 can be provided between the heating block and the cooling enclosure. This comprises a narrow blade arranged between the edges of the tape. It presses upon the fibres protruding between the edges of the tape to return them into the body of the rod.

In this embodiment the function of the steam is to heat the cellulose acetate and glyceryl triacetate so that the solvent action of the glyceryl triacetate upon the cellulose acetate is accelerated. Thus solvent welding of the cellulose acetate fibres occurs. In the case of other fibrous materials or other bonding constituents the heating effect of the steam may accelerate the bonding by causing fusion or polymerisation. Figure 3 illustrates a cutting device according to the invention which could be used for the cutting device 13 of Figs 1 and 2.

In the Figure 3 device, a first tow inlet stuffer jet 50a, supplied with pressurised air via conduit and jacket (not shown), draws first tow stream 2a from rollers (not shown) through the relatively restricted orifice of first tow inlet ledger 56a. A second tow inlet stuffer jet 50b, supplied with pressurised air via conduit and jacket (not shown), draws second tow stream 2b from rollers (not shown) through the relatively restricted orifice of second tow inlet ledger 56b. A first fibre outlet ledger 58a, arranged in line with and spaced downstream of the first tow inlet ledger 56a, is disposed at the inlet end of fibre exit jet 64. A second fibre outlet ledger 58b, arranged in line with and spaced downstream of the second tow inlet ledger 56b, is also disposed at the inlet end of fibre exit jet 64. A knife blade 60 is mounted on a rotary disc 62 so that its circular travel path passes between each pairs of ledgers 56a, 58a and 56b, 58b once per rotation to intersect the passing first and second streams of tow 2a and 2b and cut the tow into substantially uniform fibre lengths, this fibre length being the longitudinal distance by which the tow is advanced (through ledgers 56a, 56b) per revolution of the disc. Exit jet 64 is supplied with pressurised air via conduit and jacket (not shown) so that the cut fibres are immediately swept downstream through fibre outlet ledgers 58a, 58b into a venturi funnel 65. Thus, as the knife blade 60 passes between first ledgers 56a, 58a it intersects and cuts the passing first stream of tow 2a into a (first) flow of cut fibres from the first tow stream which is

immediately swept downstream through fibre outlet ledgers 58a into venturi funnel 65. The knife blade 60 finishes cutting the first stream of tow 2a and continues its rotation so that it passes between second ledgers 56b, 58b and intersects and cuts the passing second stream of tow 2b into a (second) flow of cut fibres from the second tow stream which is immediately swept downstream through fibre outlet ledgers 58b into venturi funnel 65, following the stream of cut fibres from the first tow stream. The knife blade 60 finishes cutting the second stream of tow 2b and continues its rotation so that it completes a full circle (one rotation), and then continues into a second rotation during which it passes again between the first ledgers 56a, 58a to cut (again) the advancing first stream of tow 2a to provide a further flow of cut fibres from the first tow stream which is also immediately swept downstream through fibre outlet ledger 58a into venturi funnel 65, following that from the second cut stream. In this way the first and second tow streams 2a, 2b are cut one at a time (one after the other) to thereby provide substantially alternating flows of cut fibres from the first and second tow streams, which are then are swept into the venturi funnel and merged into a single product flow of cut fibres. As shown in Fig. 3, funnel 65 of exit jet 64 may be connected directly to the inlet of air permeable frusto-conical screen 21 of the apparatus of Figs. 1 and 2.

The first and second streams of tow 2a, 2b are generally fed (advanced through ledgers 56a, 56b) to the rotary knife blade 60 simultaneously. However, in another example, the first and second streams of tow 2a, 2b may be fed to the rotary knife blade alternately, so while the first stream of filamentary tow 2a is being advanced through ledger 56a toward the rotary knife blade 60 for cutting, the second stream of filamentary tow 2b is (substantially) stationary; and when the second stream of filamentary tow 2b is being advanced through ledger 56b toward the rotary knife blade 60 for cutting, the first stream of filamentary tow is (substantially) stationary. Figure 4 illustrates another example of a cutting device according to the invention which could be used for the cutting device 13 of Figs 1 and 2.

In the Figure 4 device, a first tow inlet stuffer jet 50'a, supplied with pressurised air via conduit and jacket (not shown), draws first tow stream 2'a from rollers (not shown) through the relatively restricted orifice of first tow inlet ledger 56'a. A second tow inlet stuffer jet 50'b, supplied with pressurised air via conduit and jacket (not shown), draws second tow stream 2'b from rollers (not shown) through the relatively restricted orifice of second tow inlet ledger 56'b. A first fibre outlet ledger 58'a, arranged in line with and spaced downstream of the first tow inlet ledger 56'a, is disposed at the inlet end of fibre exit jet 64'. A second fibre outlet ledger 58'b, arranged in line with and spaced downstream of the second tow inlet ledger 56'b, is also disposed at the inlet end of fibre exit jet 64'. A knife blade 60' is mounted on a rotary disc 62' so that its circular travel path passes between each pair of ledgers 56'a, 58'a and 56'b, 58'b once per rotation to intersect the passing first and second streams of tow 2'a and 2'b and cut the tow into substantially uniform fibre lengths, this fibre length being the longitudinal distance by which the tow is advanced per revolution of the disc. Exit jet 64" is supplied with pressurised air via conduit and jacket (not shown) so that the cut fibres are immediately swept downstream, either through fibre outlet ledger 58'a into a first venturi funnel 65'a, or through fibre outlet ledger 58'b into a second venturi funnel 65'b. As shown in Fig. 4, funnels 65'a and 65'b are connected directly to the inlet of air permeable frusto-conical screen 21 of the apparatus of Figs. 1 and 2, so the cut fibres from first and second venturi funnels 65'a and 65'b may be mixed in screen 21. Thus, as the knife blade 60' passes between first ledgers 56'a, 58'a it intersects and cuts the passing first stream of tow 2'a into a (first) flow of cut fibres from the first tow stream which is immediately swept downstream through fibre outlet ledgers 58'a into venturi funnel 65'a and on into screen 21. The knife blade 60' finishes cutting the first stream of tow 2'a and continues its rotation so that it passes between second ledgers 56'b, 58'b and intersects and cuts the passing second stream of tow 2'b into a (second) flow of cut fibres from the second tow stream which is immediately swept downstream through fibre outlet ledgers 58'b into venturi funnel 65'b and on into screen 2 , thereby following the stream of cut fibres from the first tow stream into screen 21. The knife blade 60' finishes cutting the second stream of tow 2'b and continues its rotation so that it completes a full circle (one rotation), and then continues into a second rotation during which it passes again between the first ledgers 56'a, 58'a to cut (again) the first stream of tow 2'a to provide a further flow of cut fibres from the first tow stream which is also immediately swept downstream through fibre outlet ledger 58a and venturi funnel 65'a into screen 21 , following the cut fibres from the second cut stream. In this way the first and second tow streams 2a, 2b are cut one at a time (one after the other) to provide substantially alternating flows of cut fibres from the first and second tow streams, which are then swept through venturi funnels 65'a and 65b' into the inlet of air permeable frusto-conical screen 21 and merged into a single product flow of cut fibres immediately prior to and/or during condensation of the single product flow into rod form. The first and second streams of tow 2'a, 2'b are generally fed (advanced through ledgers 56'a, 56'b) to the rotary knife blade 60' simultaneously. In another example, the first and second streams of tow 2'a, 2'b may be fed to the rotary knife blade alternately, so while the first stream of filamentary tow 2'a is being advanced through ledger 56'a toward the rotary knife blade 60' for cutting, the second stream of filamentary tow 2'b is

(substantially) stationary; and when the second stream of filamentary tow 2'b is being advanced through ledger 56'b toward the rotary knife blade 60' for cutting, the first stream of filamentary tow is (substantially) stationary.

The cutting device 13 is preferably run at such a speed relative to the speed of the tow that the fibres cut from it are about the same length (e.g. 6 to 12 mm) as the diameter of the rod to be produced (e.g. about 8mm). The length of the fibres can, however, be varied, e.g. from 3mm to 50mm. Preferably, the apparatus is coated on surfaces which come into contact with the tow and with the plasticiser with a substance which prevents adhesion.

In one embodiment of the invention the knife blade 60 (or 60') mounted on a rotary disc 62 (or 62') includes one or more venting holes. The (or each) venting hole allows passage of gas (air) through the (or each) knife blade in the direction in which the tow is travelling, thereby enabling an increase in production line speeds.

The rods made as described above are deformation-resistant in that they may be handled by known cigarette filter rod handling devices without an unacceptable distortion. A paper wrapping may however facilitate some steps in the subsequent utilisation of the rods. If such a rod is desired it may be made by providing the plug-maker 20 with an additional drum similar to the drum 26 and garniture and roller system. The garniture is located downstream of the cooling enclosure and before the cut off. It is used to wrap paper around the continuous rod 31 as it comes from the cooling enclosure and adhere it around the rod by means of a lapped and stuck seam. The two tapes, i.e. the tape 22 and the tape passing through the garniture, will have a substantially identical linear speed, though the tape 22 may be run slightly faster than the garniture tape so as to prevent any tensile breakage in the fibrous rod as it is transferred from the cooling enclosure to the garniture.

Other materials such as fibres of paper pulp may be incorporated with the fibres cut from the filaments of the tow by feeding them simultaneously with the latter into the cutter 13 so that together they are dispersed in air, become blended, enter the heating enclosure and are bonded into a homogeneous rod.

Various filamentary tows such as polypropylene, polyethylene, cellulose triacetate, nylon or viscose may be used where their particular physical or chemical properties are needed, but for cigarette filters secondary cellulose acetate is preferred. Other bonding constituents such as fusible resins and fibres may be used instead of solvent plasticisers. Other plasticisers such as triethylene glycol diacetate may be used in place of glyceryl triacetate.

Whilst the method and apparatus illustrated in Figures 1 and 2 employs a heating block to activate a bonding constituent on the fibres to yield a bonded rod, this is not essential. For example, the fibre (with or without bonding constituent) from the outlet of cone 21 could be deposited instead on a strip of conventional plug-wrap and passed through a conventional wrapping garniture to yield a wrapped rod. In all rod formation embodiments according to the invention, there may be continuous in-line travel of the filter material through the tow preparation, tow cutting, and fibre rod information stages.

To take account of the longitudinal movement of the tow being cut, and hence facilitate a cleaner cut and more uniform cut fibre length, the ledgers may be oscillated along the tow path.

In another embodiment, the apparatus of Figs. 1, 2, 3 and 4 may further comprise a ventilator for one (or each) ledger. The ventilator(s) allow increased air flow through the cutter, thereby allowing increased machine speed while maintaining cut fibre (staple fibre) length and PD variation in the resulting rod formed from the cut fibres.

Claims

1. An in-line apparatus for continuously cutting filamentary tow into fibres, the apparatus comprising:

a first tow inlet feeder including a first tow inlet ledger for feeding a first stream of filamentary tow through the first tow inlet ledger;

a second tow inlet feeder including a second tow inlet ledger for feeding a second stream of filamentary tow through the second tow inlet ledger;

at least one knife blade arranged for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow and cut the streams into a flow of cut fibres from the first stream of filamentary tow and a flow of cut fibres from the second stream of filamentary tow; and

at least one cut fibre exit gas jet arranged in line with the tow inlet ledgers for carrying the resulting flow of cut fibres from the first stream of filamentary tow and flow of cut fibres from the second stream of filamentary tow away from the knife blade and through the first and second outlet ledgers;

2. An in-line apparatus for continuously cutting filamentary tow into cut fibres, the apparatus comprising:

at least one knife blade arranged for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one stream at a time and thereby cut the streams into substantially alternating flows of cut fibres from the first and second tow streams, and

at least one cut fibre exit gas jet arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres.

3. An apparatus according to claim 1 or claim 2 comprising 2, 3, 4, 5, 6, 12 or 24 knife blade(s) arranged for periodic passage between the tow inlet and fibre outlet ledgers.

4. An apparatus according to any preceding claim wherein the knife blade (or blades) are rotatably mounted so the (or each) blade passes between each inlet and outlet ledger once per rotation.

5. An apparatus according to any preceding claim for continuously cutting filamentary tow into fibres and condensing the cut fibres to rod form, further comprising a unit for separating air from the cut fibres and condensing the latter to rod form.

6. An apparatus according to any preceding claim wherein the unit for separating air from the cut fibres and condensing the latter to rod form includes an air permeable frusto- conical screen.

7. An apparatus according to any preceding claim wherein the unit for separating air from the cut fibres and condensing the latter to rod form is attached directly to the outlet(s) of the fibre exit jet(s).

8. An in-line apparatus for continuously cutting filamentary tow into fibres and condensing the cut fibres to rod form, the apparatus comprising.

a second fibre outlet ledger arranged in line with and spaced downstream of the second tow inlet ledger; at least one knife blade arranged for periodic passage between the tow inlet and fibre outlet ledgers to intersect the passing first and second streams of filamentary tow one at a time and thereby cut the streams into substantially alternating flows of cut fibres from the first and second tow streams;

at least one cut fibre exit gas jet arranged in line with the tow inlet ledgers for carrying the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade and through the first and second outlet ledgers, respectively, for subsequent merging into a single product flow of cut fibres; and a unit for separating air from the product flow of cut fibres and condensing the latter to rod form.

9. An apparatus according to any preceding claim wherein the cut fibre exit gas jet includes a funnel downstream of the first and second fibre outlet ledgers.

10. An apparatus according to any of claims 1 to 8 wherein the cut fibre exit gas jet includes a first funnel downstream of the first fibre outlet ledger, and a second funnel downstream of the second fibre outlet ledger.

11. An apparatus according to any preceding claim wherein the knife blade includes one or more venting holes.

12. An apparatus according to any preceding claim further comprising a ventilator for at least one ledger.

13. An in-line method of cutting filamentary tow into fibres and, optionally, condensing the cut fibres to rod form, the method comprising: feeding first and second streams of filamentary tow to a rotary knife blade whose rotary path periodically intersects the paths of the tow streams one at a time and thereby cuts the streams into substantially alternating flows of cut fibres from the first and second tow streams; carrying, by means of an exit gas jet acting in-line with the tow feeds, the resulting substantially alternating flows of cut fibres from the first and second tow streams away from the knife blade; and merging the substantially alternating flows of cut fibres from the first and second tow streams into a single product flow of cut fibres.

14. A method according to claim 13 comprising a further step of separating air from the cut fibres and condensing the latter to rod form.

15. A method according to claims 13 or 14 in which the first and second streams of tow are different tow materials.

16. A method of continuously cutting filamentary tow into fibres and condensing the cut fibres to rod form substantially as hereinbefore described with reference to Figures 1 , 2 and 3; or 1 , 2 and 4.

17. An apparatus for continuously cutting filamentary tow into fibres and condensing the cut fibres to rod form substantially as hereinbefore described with reference to Figures 1 , 2 and 3; or 1 , 2 and 4.

18. A double or higher multiple length filter or filter element comprising a filter rod produced by a method according to any of claims 13 to 16, or produced using an apparatus according to any of claims 1 to 12 or 17.

19. A method of manufacture of a smoking article comprising a step of applying a tobacco smoke filter comprising a filter rod produced by a method according to any of claims 13 to 16, or produced using an apparatus according to any of claims 1 to 12 or 17, or a filter including a filter element comprising a filter rod produced by a method according to any of claims 13 to 16, or produced using an apparatus according to any of claims 1 to 12 or 17, to a wrapped rod of smoking material.

20. A filter cigarette comprising a filter rod produced by a method according to any of claims 13 to 16, or produced using an apparatus according to any of claims 1 to 12 or 17, or a filter including a filter element comprising a filter rod produced by a method according to any of claims 13 to 16, or produced using an apparatus according to any of claims 1 to 12 or 17, joined to a wrapped tobacco rod with one end towards the tobacco.