CA1189784A - Tow cutter - Google Patents
Tow cutterInfo
- Publication number
- CA1189784A CA1189784A CA000406575A CA406575A CA1189784A CA 1189784 A CA1189784 A CA 1189784A CA 000406575 A CA000406575 A CA 000406575A CA 406575 A CA406575 A CA 406575A CA 1189784 A CA1189784 A CA 1189784A
- Authority
- CA
- Canada
- Prior art keywords
- tow
- fibres
- cut
- rod
- ledgers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
- D01G1/00—Severing continuous filaments or long fibres, e.g. stapling
- D01G1/02—Severing continuous filaments or long fibres, e.g. stapling to form staple fibres not delivered in strand form
- D01G1/04—Severing continuous filaments or long fibres, e.g. stapling to form staple fibres not delivered in strand form by cutting
-
- A—HUMAN NECESSITIES
- A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
- A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
- A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
- A24D3/02—Manufacture of tobacco smoke filters
- A24D3/0204—Preliminary operations before the filter rod forming process, e.g. crimping, blooming
- A24D3/0208—Cutting filter materials
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Cigarettes, Filters, And Manufacturing Of Filters (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In-line apparatus for continuously cutting fila-mentary tow into fibres and delivering the cut fibres in a continuous stream, the apparatus comprising a tow inlet feeder and a cut fibre exit gas jet arranged in-line and separated by ledgers, and a knife blade rotatably mounted for periodic passage between adjacent ledgers to intersect tow passing therepast and cut it into fibres. The cut fibres are carried directly to an air separator from which they are deposited in a device for forming them into filter rods.
In-line apparatus for continuously cutting fila-mentary tow into fibres and delivering the cut fibres in a continuous stream, the apparatus comprising a tow inlet feeder and a cut fibre exit gas jet arranged in-line and separated by ledgers, and a knife blade rotatably mounted for periodic passage between adjacent ledgers to intersect tow passing therepast and cut it into fibres. The cut fibres are carried directly to an air separator from which they are deposited in a device for forming them into filter rods.
Description
~rlle present invention re]ates to the cuttiny of Eilamerltary tow into short, e.g. staple fibres.
~.K. Specification No. 1,221,3~6 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 cut-ter 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 uni-t where the fibres are separated from the air stream and condensed to rod form for filter production. This is a commercial process, but its rate of -throughpu-t is not as high as is desirable, and various at-tempts to increase the rate of operation have led to un-desirable lack of uniformity in the cut fibre leng-th and/or in the distribution of the fibres in the rod product.
The present invention provides in-line apparatus for continuously cu-tting filamen-tary -tow into fibres and delivering the cut fibres in a continuous stream, the appara-tus comprising a -tow inlet feeder and a cut fibre exit gas jet arranged ln-line and separa-ted by ledgers, and a knife blade rotatably mounted for periodic passage between adja-cent ledgers to intersect tow passing therepast and cut i-t into fibres. Preferably at leas-t the downstream ledger is annular with the material path extending -therethrough. Any tow feed to the ledgers may be used, bu-t a stuffer jet may be preferred. The invention also provides an in-line method of continuously cutting filamentary tow in-to fibres and deli-vering the cu-t fibres in a con-tinuous stream, the method comprising feeding the tow continuously to a rotary knife blade whose ro-tary path periodically in-tercepts the path of the tow, and immediately carrying the resulting cut fibres away from the knife blade by means of an exi-t gas ~et acting in-line wi-th -the tow feed. A wholly in-line path is thus 7~
prov:idecl for the passage of the -tow to the cutter and of the cut Eibres therefrom. Furthermore, a unit for separating air from the cu-t fibres and condensing the lat-ter to rod form can be attached directly -to the outlet of the flbre exit jet, thus permitting minimum -travel of the cut fibres prior -to rod formation.
The apparatus according -to the invention can be operated sa-tisfactorily at higher -throughpu-t rates than the 10' apparatus previously proposed and used.
When cutting apparatus according -to -the invention is employed as described above for the fully in-line pro-duction of cut fibre filter rods from filamentary tow (i.e.
with -the fibre exit jet connec-ted directly and in-line with the air separa-tor and rod forma-tion unit), the resul-ting rods have a detectable distinct fibre structure different from -that of rods produced by the mentioned prior process.
In rods obtained by the prior process, the fibres are ran-domly oriented, bu-t with non-uniformity of fibre length and packing along the rod length; in rod s f'ormclti()rl accordin to t,he invent,iorl, the f:ihres tend to remaill in t~leir initially cut clumps as they travel to and through the air separator and rod forlller. Accord:ingly the inverltion also provides a f'ilter rod of cut fibres maintained in coherent rod form, the fibres being packed in clumps with the fibres of a clump being of' substantially the same length; the clumps are usual:Ly of substantially the same g:irth. The tow may be cut into fibre clumps of equal length, or into clumps of two or (less usually) more ( 10 different lengths. The clumps in the finished rod may tend to be packed with the fibres oriented transversely to the rod a~is. In rods according to the invention the fibre packing can be more uniform along the rod ],ength than in the prior products.
In apparatus according to the invention, a single knife blade may be mounted, e.g. on a rotary disc, for co~operation with a single pair of ledgers, but other ,, arrangements are possible. For example, two longitudinally spaced pairs of ledgers could be provided, with a corresponding pair of knife blades being mounted (usually in circumfcrential register) on the rotary disc. In other embodiments, a plurality of knife blades or blade pairs may be spaced circumferentially around the rotary disc to provide for a corresponding plurality of cutting actions per revolution of the disc.
. .
Th~ apparatus according to the invention ls normally mounted with the tow and fibre paths.horizontal and the knife pa~hs vertical.
The invention is illustrateclg by way of example only~ by the accompanying drawings9 in which like numerals represent like parts and in which :-Figure 1 is a diagrammatic elevation view ofa complete filter rod production apparatus according to ( the invent~on;
Figure 2 is a similar enlargedview of the air separation and rod formation portion of the Fig.l apparatus;
Figure 3 is a diagrammatic side elevation view, partly in sectiong Or a tow cutting device according to the invention suitable for use in the Fig.l apparatus;
Figure 4 is a similar view of a modified tow cutting device according to the invention~
Figure 5 is a diagrammatic side elevation in section of a prior fibre filter rod; and Figure 6 is a similar view of a ~ilter rod according to th~ invention made using the apparatus of Figs.l to 3.
In ~he illustrated filter ro~ production method and apparatus d~scribed below~ the rod is made from ~5 cellu~ose acetate continuous filamentary tow plasticised 9~
wi.th glyceryl triacetate; th;.s is the preferred material for cigarette filter production, but a variety of other materials can be used.
Referring to the drawings, from a ~ale 1 of continuous filametary cellulose acetate tow, the tow 2 i.s drawn upwardly first through an air banding jet Ij, thence over a cyl.i.ndrical guide 5, traction being given by rollers 3. The tow 2 then passes to rollers 6 which rotate faster than rollers 3 and thereby stretch the.tow betweem them and rollers 3. A further air banding jet 7 forms the tow into a band which form it retains as it passes into box 10 where it is sprayed over the whole of its width with glyceryl triacetate is known manner. The banding jets 4 and 7 are of known form and comprise a --15 sloi; through which the tow passes, having on one side a.
( wall, divided by narrow slits to the outer side of which c.ompressed air is supplied. This air passes through the slits and impinges upon the tow. On the other side of the slot is an undivided wall which retains the tO.I while the air imp;.nges upon it. Rollers 11 hold the ~ow ill band form until it enters the cutting device13 according to the invention. A rotary knife cutter within the cutting device is driven by a belt~ not shown, ~hich is driven, v;.a an infinitely va:riable ~,elr, from the main--25 shaft of a plug-malcer 20, as are rol~.ers 3, 6 and 11 vla olher such gears. By va-ry:ing ~he relil~;lve rates Or rotat:;on Or the cutter and the ro~lers ll the leng~h of the fibres may be varied. By varylng the relative rates of rotation Or the rollers 3, 6 and ll the we:ieht per unit length of the rod may be varied ~ e.g. by varying the rate of rotation of rollers 3 relatively to rollers 6, the percentage crirnp of the filaments entering the cutting device 13 ls altered. The cutting device 13 is described hereinbelow with reference to Figs.~ and 4 .
10The combined delivery stream of air and fibre from cutting device 1-~ passes through exit 18 into an air permeable, e.g. perforate, frusto-conical screen 21, preferably formed of wire mesh, through the wall Or which most of the air escapes. 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 wire mesh can for example have openings 0.12 mrn square. The remainder of th2 air deposits the fibres on ( a pervious tape 22 and then passes out of holes in a surrounding heating block 24. The latter has a bore 25 through which the tape passes. The bore has a cross section corresponding to the cross section desired in the rod, e.g. it is circular. ~t 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. lt is preferred that the fibres rema:in ln suspension until they meet the tape 22. ~lowever it is undes.i.rab:l.e t~a~; arl excessive a:;.r r].ow be use(l Llor thi..;
purpose as Iibres may be blown into the atmosphere instead Or heing deposi.ted. The rate of flow may be increased by bloclcing off a part of the screen 2:l. next to the e~it 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 ( 10 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, contairling 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 deli.vered. 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 de:Livery band 35, or first to a wrapping garniture where the fibrous rod is wrapped with a paper wrapper in knowrl manner and thence to the cut-off.
If the edges of the tape 22 as they envelop the fibrous mat;erial do not meet perfectly, fibres press Pi'~
betweerl theln c-lrld .f'o:rrn a ri.dge. To el.i.rn:i.rlate t}ll,s a rid~e rernover 4]. can be provi..ded betweell the heati.ng bl.ock and the cooling enc~losl1re. Thi.s cornprises a narrow blade arranged between the edges of the tape. lt 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 khat the solvent action of th.e 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 bondi.ng by causing fusi.on or polymerisation.
Figures 3 and 4 illustrate cutting dev;.ces ~ccording to the invention which could be used for the cutting device 13 of Fi.gs.l and 2.
In the Figure 3 device tow inlet stuf~er jet 50, ( supplied with pressurised air via conduit 52 and jacket 54, draws tow 2 from rollers 11 through the relativel~
restricted orifices 56 of ledgers 58. A knife blade 60 is mounted on a rotary disc 62 so that its circular travel path passes between ledgers 58 once per rotation to cut the tow into substantially uniform fibre lengths, this fibre length of course being the longitudinal distance by which the tow is advanced per revolution of' the disc.
The downstream ledger 58 is disposed at the inlet end Or fibre exit jet 64 which is supplied with pressurised air .
c ~ 71~
. , via cor-ldu~ )6 and jacket; 6~ so thl~ the cut f'ibres are -;mmed:iate:ly swept from the downstream annular Ledger to '' the widened exit 18 Or jet 6ll. As shown in ~ig.~, this exit rnay be connected directly to the inlet of mesh cone 21 of the apparatus of Figs.l and'2.
The ~igure 4 cutting device is essentially the same, except that three ledgers 58 are provided between the two jets, a pair of knives 60 being mounted in circumferential register on disc 62 to pass simultaneously as shown between the corresponding two ledger gaps.
l'he cutting device 13 is preferably run at such a speed relative to the speed of the tow that the fibres cut f'rom it are about the same length (e.g. 6 to 12 mm) as the diameter of the rod to be produced (e.g. about 8 mm). The length of the fibres can, however, be varied, e.g. from 3 mm to 50 mm. Preferably the apparatus is coated on surfaces which come into contact with thè tow - and with the plasticiser with a substance which prevents (, adhesion~
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 provid~ng the plug-maker 20 with an additional drum similar to the drum 26 and a garniture and roller system. The garnil;ure is located downstrea1n Or the cooling enclosure and before 3'7~
.lo t~.e Cll'.; of r. :[ t i.S IlSeCI to wrap paper aroulld t~le cont;nllous rod ~1 as it; comes fror(l ~he cooling encLosure and adllere it around t}le rod by rneans 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 ident;cal linear speed, though the tape 22 may be run slight:ly faster than the garniture tape so as to prevent any tensile breakage in the fibrous rod as it is trans-ferred f'rom the cooling enclosure to the garniture.
Using this apparatus f`ilter rods for cigarettes may be made which have a higher pressure drop or a greater hardness than rods of an equal weight made by the conventional tow processes. Alternatively rods of equivalent properties may be made using less tow than the conventional process. This advantage which is believed to result from a more favourable arrangement of ~he fibres in the rod, as a result of the method of deposition of - the fibres, produces a saving Or tow.
( Other materials such as fibres of paper pulp may be incorporated with the fibres cut frorn the filaments of the tow by feèding them sirnultaneously 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.
~ ~arious fi:lamentary tows such as polypropylene, polyethylene, cellulose triacetate, ny'lon or viscose may be used where their part;cular physical or chemical properties are needed, but for cigarette fili;ers secondary 37~
celluloc;e acetate is preferred. Other bonding constitllerlts such 1S fusible resins and fibres may be used instead Or solven~ p~a~ticisers. Ot;her plasticisers such as triethylene glycol diacetate may be used in place oL
glyceryl triacetate.
Whilst the method and apparatus illustrated in ~igures 1 and 2 employ 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 is continuous in-line travel of the filter material through the tow preparation, tow cutting, and fibre rod formation stages.
Figures 5 and 6 illustrate diagrammatically ( respectively a filter rod produced by the prior method and apparatus employing an impeller fan with initial travel of the cut fibres perpendicular to the tow feed, and a rod according to the invention produced by the method and apparatus of Figs.l to 3. In Figure 5 the fibres 80 within plugwrap 82 vary apprec;ably in length and are randomly uriented, and in practice there are variations in fibre length and distribution along the length of thc rod. In the Figure 6 rod according to the invention, the fibres 80 are of substantially un;form 7~
~ l? -1.ength and are r)acked in dist;i.ng~l;.shablc c:l.u~nps ~ll whi.chare o:f sul)stallt:;a:l].~ the same girth, l;he f'i.bres Or a clump being disposecl generally parallel to one anot;her and general1.y transverse to the rod axis; the rod diarne-ter is for example about 8 mm, with the fibre length being about 1.2 mm. The improved uni.formity of the rods according to the invention results in improved uniformity in pressure drop amongst the individual filter plugs cut from the initia:L1.y produced continuous rod. It will ~e ( lO apprec;ated that, instead of cutting the tow into clumps of equal length~ fibre clumps of two or more different predetermined lengths are obtainable by appropriate arrangement of a plurality of knife blades.
To take account of the longitudinal movement of the tow being cut, and hence facilitate a cl.eaner cut and more uniform cut fibre length, the ledgers may be oscillatecl along the tow path.
~.K. Specification No. 1,221,3~6 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 cut-ter 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 uni-t where the fibres are separated from the air stream and condensed to rod form for filter production. This is a commercial process, but its rate of -throughpu-t is not as high as is desirable, and various at-tempts to increase the rate of operation have led to un-desirable lack of uniformity in the cut fibre leng-th and/or in the distribution of the fibres in the rod product.
The present invention provides in-line apparatus for continuously cu-tting filamen-tary -tow into fibres and delivering the cut fibres in a continuous stream, the appara-tus comprising a -tow inlet feeder and a cut fibre exit gas jet arranged ln-line and separa-ted by ledgers, and a knife blade rotatably mounted for periodic passage between adja-cent ledgers to intersect tow passing therepast and cut i-t into fibres. Preferably at leas-t the downstream ledger is annular with the material path extending -therethrough. Any tow feed to the ledgers may be used, bu-t a stuffer jet may be preferred. The invention also provides an in-line method of continuously cutting filamentary tow in-to fibres and deli-vering the cu-t fibres in a con-tinuous stream, the method comprising feeding the tow continuously to a rotary knife blade whose ro-tary path periodically in-tercepts the path of the tow, and immediately carrying the resulting cut fibres away from the knife blade by means of an exi-t gas ~et acting in-line wi-th -the tow feed. A wholly in-line path is thus 7~
prov:idecl for the passage of the -tow to the cutter and of the cut Eibres therefrom. Furthermore, a unit for separating air from the cu-t fibres and condensing the lat-ter to rod form can be attached directly -to the outlet of the flbre exit jet, thus permitting minimum -travel of the cut fibres prior -to rod formation.
The apparatus according -to the invention can be operated sa-tisfactorily at higher -throughpu-t rates than the 10' apparatus previously proposed and used.
When cutting apparatus according -to -the invention is employed as described above for the fully in-line pro-duction of cut fibre filter rods from filamentary tow (i.e.
with -the fibre exit jet connec-ted directly and in-line with the air separa-tor and rod forma-tion unit), the resul-ting rods have a detectable distinct fibre structure different from -that of rods produced by the mentioned prior process.
In rods obtained by the prior process, the fibres are ran-domly oriented, bu-t with non-uniformity of fibre length and packing along the rod length; in rod s f'ormclti()rl accordin to t,he invent,iorl, the f:ihres tend to remaill in t~leir initially cut clumps as they travel to and through the air separator and rod forlller. Accord:ingly the inverltion also provides a f'ilter rod of cut fibres maintained in coherent rod form, the fibres being packed in clumps with the fibres of a clump being of' substantially the same length; the clumps are usual:Ly of substantially the same g:irth. The tow may be cut into fibre clumps of equal length, or into clumps of two or (less usually) more ( 10 different lengths. The clumps in the finished rod may tend to be packed with the fibres oriented transversely to the rod a~is. In rods according to the invention the fibre packing can be more uniform along the rod ],ength than in the prior products.
In apparatus according to the invention, a single knife blade may be mounted, e.g. on a rotary disc, for co~operation with a single pair of ledgers, but other ,, arrangements are possible. For example, two longitudinally spaced pairs of ledgers could be provided, with a corresponding pair of knife blades being mounted (usually in circumfcrential register) on the rotary disc. In other embodiments, a plurality of knife blades or blade pairs may be spaced circumferentially around the rotary disc to provide for a corresponding plurality of cutting actions per revolution of the disc.
. .
Th~ apparatus according to the invention ls normally mounted with the tow and fibre paths.horizontal and the knife pa~hs vertical.
The invention is illustrateclg by way of example only~ by the accompanying drawings9 in which like numerals represent like parts and in which :-Figure 1 is a diagrammatic elevation view ofa complete filter rod production apparatus according to ( the invent~on;
Figure 2 is a similar enlargedview of the air separation and rod formation portion of the Fig.l apparatus;
Figure 3 is a diagrammatic side elevation view, partly in sectiong Or a tow cutting device according to the invention suitable for use in the Fig.l apparatus;
Figure 4 is a similar view of a modified tow cutting device according to the invention~
Figure 5 is a diagrammatic side elevation in section of a prior fibre filter rod; and Figure 6 is a similar view of a ~ilter rod according to th~ invention made using the apparatus of Figs.l to 3.
In ~he illustrated filter ro~ production method and apparatus d~scribed below~ the rod is made from ~5 cellu~ose acetate continuous filamentary tow plasticised 9~
wi.th glyceryl triacetate; th;.s is the preferred material for cigarette filter production, but a variety of other materials can be used.
Referring to the drawings, from a ~ale 1 of continuous filametary cellulose acetate tow, the tow 2 i.s drawn upwardly first through an air banding jet Ij, thence over a cyl.i.ndrical guide 5, traction being given by rollers 3. The tow 2 then passes to rollers 6 which rotate faster than rollers 3 and thereby stretch the.tow betweem them and rollers 3. A further air banding jet 7 forms the tow into a band which form it retains as it passes into box 10 where it is sprayed over the whole of its width with glyceryl triacetate is known manner. The banding jets 4 and 7 are of known form and comprise a --15 sloi; through which the tow passes, having on one side a.
( wall, divided by narrow slits to the outer side of which c.ompressed air is supplied. This air passes through the slits and impinges upon the tow. On the other side of the slot is an undivided wall which retains the tO.I while the air imp;.nges upon it. Rollers 11 hold the ~ow ill band form until it enters the cutting device13 according to the invention. A rotary knife cutter within the cutting device is driven by a belt~ not shown, ~hich is driven, v;.a an infinitely va:riable ~,elr, from the main--25 shaft of a plug-malcer 20, as are rol~.ers 3, 6 and 11 vla olher such gears. By va-ry:ing ~he relil~;lve rates Or rotat:;on Or the cutter and the ro~lers ll the leng~h of the fibres may be varied. By varylng the relative rates of rotation Or the rollers 3, 6 and ll the we:ieht per unit length of the rod may be varied ~ e.g. by varying the rate of rotation of rollers 3 relatively to rollers 6, the percentage crirnp of the filaments entering the cutting device 13 ls altered. The cutting device 13 is described hereinbelow with reference to Figs.~ and 4 .
10The combined delivery stream of air and fibre from cutting device 1-~ passes through exit 18 into an air permeable, e.g. perforate, frusto-conical screen 21, preferably formed of wire mesh, through the wall Or which most of the air escapes. 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 wire mesh can for example have openings 0.12 mrn square. The remainder of th2 air deposits the fibres on ( a pervious tape 22 and then passes out of holes in a surrounding heating block 24. The latter has a bore 25 through which the tape passes. The bore has a cross section corresponding to the cross section desired in the rod, e.g. it is circular. ~t 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. lt is preferred that the fibres rema:in ln suspension until they meet the tape 22. ~lowever it is undes.i.rab:l.e t~a~; arl excessive a:;.r r].ow be use(l Llor thi..;
purpose as Iibres may be blown into the atmosphere instead Or heing deposi.ted. The rate of flow may be increased by bloclcing off a part of the screen 2:l. next to the e~it 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 ( 10 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, contairling 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 deli.vered. 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 de:Livery band 35, or first to a wrapping garniture where the fibrous rod is wrapped with a paper wrapper in knowrl manner and thence to the cut-off.
If the edges of the tape 22 as they envelop the fibrous mat;erial do not meet perfectly, fibres press Pi'~
betweerl theln c-lrld .f'o:rrn a ri.dge. To el.i.rn:i.rlate t}ll,s a rid~e rernover 4]. can be provi..ded betweell the heati.ng bl.ock and the cooling enc~losl1re. Thi.s cornprises a narrow blade arranged between the edges of the tape. lt 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 khat the solvent action of th.e 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 bondi.ng by causing fusi.on or polymerisation.
Figures 3 and 4 illustrate cutting dev;.ces ~ccording to the invention which could be used for the cutting device 13 of Fi.gs.l and 2.
In the Figure 3 device tow inlet stuf~er jet 50, ( supplied with pressurised air via conduit 52 and jacket 54, draws tow 2 from rollers 11 through the relativel~
restricted orifices 56 of ledgers 58. A knife blade 60 is mounted on a rotary disc 62 so that its circular travel path passes between ledgers 58 once per rotation to cut the tow into substantially uniform fibre lengths, this fibre length of course being the longitudinal distance by which the tow is advanced per revolution of' the disc.
The downstream ledger 58 is disposed at the inlet end Or fibre exit jet 64 which is supplied with pressurised air .
c ~ 71~
. , via cor-ldu~ )6 and jacket; 6~ so thl~ the cut f'ibres are -;mmed:iate:ly swept from the downstream annular Ledger to '' the widened exit 18 Or jet 6ll. As shown in ~ig.~, this exit rnay be connected directly to the inlet of mesh cone 21 of the apparatus of Figs.l and'2.
The ~igure 4 cutting device is essentially the same, except that three ledgers 58 are provided between the two jets, a pair of knives 60 being mounted in circumferential register on disc 62 to pass simultaneously as shown between the corresponding two ledger gaps.
l'he cutting device 13 is preferably run at such a speed relative to the speed of the tow that the fibres cut f'rom it are about the same length (e.g. 6 to 12 mm) as the diameter of the rod to be produced (e.g. about 8 mm). The length of the fibres can, however, be varied, e.g. from 3 mm to 50 mm. Preferably the apparatus is coated on surfaces which come into contact with thè tow - and with the plasticiser with a substance which prevents (, adhesion~
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 provid~ng the plug-maker 20 with an additional drum similar to the drum 26 and a garniture and roller system. The garnil;ure is located downstrea1n Or the cooling enclosure and before 3'7~
.lo t~.e Cll'.; of r. :[ t i.S IlSeCI to wrap paper aroulld t~le cont;nllous rod ~1 as it; comes fror(l ~he cooling encLosure and adllere it around t}le rod by rneans 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 ident;cal linear speed, though the tape 22 may be run slight:ly faster than the garniture tape so as to prevent any tensile breakage in the fibrous rod as it is trans-ferred f'rom the cooling enclosure to the garniture.
Using this apparatus f`ilter rods for cigarettes may be made which have a higher pressure drop or a greater hardness than rods of an equal weight made by the conventional tow processes. Alternatively rods of equivalent properties may be made using less tow than the conventional process. This advantage which is believed to result from a more favourable arrangement of ~he fibres in the rod, as a result of the method of deposition of - the fibres, produces a saving Or tow.
( Other materials such as fibres of paper pulp may be incorporated with the fibres cut frorn the filaments of the tow by feèding them sirnultaneously 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.
~ ~arious fi:lamentary tows such as polypropylene, polyethylene, cellulose triacetate, ny'lon or viscose may be used where their part;cular physical or chemical properties are needed, but for cigarette fili;ers secondary 37~
celluloc;e acetate is preferred. Other bonding constitllerlts such 1S fusible resins and fibres may be used instead Or solven~ p~a~ticisers. Ot;her plasticisers such as triethylene glycol diacetate may be used in place oL
glyceryl triacetate.
Whilst the method and apparatus illustrated in ~igures 1 and 2 employ 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 is continuous in-line travel of the filter material through the tow preparation, tow cutting, and fibre rod formation stages.
Figures 5 and 6 illustrate diagrammatically ( respectively a filter rod produced by the prior method and apparatus employing an impeller fan with initial travel of the cut fibres perpendicular to the tow feed, and a rod according to the invention produced by the method and apparatus of Figs.l to 3. In Figure 5 the fibres 80 within plugwrap 82 vary apprec;ably in length and are randomly uriented, and in practice there are variations in fibre length and distribution along the length of thc rod. In the Figure 6 rod according to the invention, the fibres 80 are of substantially un;form 7~
~ l? -1.ength and are r)acked in dist;i.ng~l;.shablc c:l.u~nps ~ll whi.chare o:f sul)stallt:;a:l].~ the same girth, l;he f'i.bres Or a clump being disposecl generally parallel to one anot;her and general1.y transverse to the rod axis; the rod diarne-ter is for example about 8 mm, with the fibre length being about 1.2 mm. The improved uni.formity of the rods according to the invention results in improved uniformity in pressure drop amongst the individual filter plugs cut from the initia:L1.y produced continuous rod. It will ~e ( lO apprec;ated that, instead of cutting the tow into clumps of equal length~ fibre clumps of two or more different predetermined lengths are obtainable by appropriate arrangement of a plurality of knife blades.
To take account of the longitudinal movement of the tow being cut, and hence facilitate a cl.eaner cut and more uniform cut fibre length, the ledgers may be oscillatecl along the tow path.
Claims (8)
1. In-line apparatus for continuously cutting filamentary tow onto fibres and delivering the cut fibres in a continuous stream, the apparatus comprising a tow inlet feeder and a cut fibre exit gas jet arranged in-line and separated by ledgers, and a knife blade rotatably mounted for periodic passage between adjacent ledgers to intersect tow passing therepast and cut it into fibres.
2. Apparatus according to claim 1 having a single knife blade or a plurality of circumferentially spaced knife blades rotatably mounted for co-operation with adjacent ledgers.
3. Apparatus according to claim 1 or 2 having at least three ledgers longitudinally spaced between said feeder and jet to provide a corresponding plurality of inter-ledger spacings each co-operating with one or more said rotatably mounted knife blades.
4. Apparatus according to claim 1 or 2 wherein at least the downstream ledger is annular with the material path extending therethrough.
5. Apparatus according to claim 1 or 2 wherein the tow inlet feeder comprises a stuffer jet.
6. Apparatus for the production of filter rods, the apparatus comprising tow cutting apparatus according to claim 1, means for supplying a continuous filamentary tow to the tow inlet feeder, and means attached directly to the outlet of the cut fibre exit jet for separating air from the cut fibres and condensing the cut fibres to permanent rod form.
7. An in-line method of continuously cutting filamentary tow into fibres and delivering the cut fibres in a continuous stream, the method comprising feeding the tow continuously to a rotary knife blade whose rotary path periodically intercepts the path of the tow, and immediately carrying the resulting cut fibres away from the knife blade by means of an exit gas jet acting in-line with the tow feed.
8. A method according to claim 7, wherein the cut fibres are conveyed directly to a unit wherein conveying air is separated from the fibres which are then condensed to permanent rod form.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08121106A GB2101642A (en) | 1981-07-08 | 1981-07-08 | Tow cutter |
| GB8121106 | 1981-07-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1189784A true CA1189784A (en) | 1985-07-02 |
Family
ID=10523102
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000406575A Expired CA1189784A (en) | 1981-07-06 | 1982-07-05 | Tow cutter |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU8565982A (en) |
| BR (1) | BR8204034A (en) |
| CA (1) | CA1189784A (en) |
| GB (1) | GB2101642A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2327201B (en) | 1997-07-14 | 2002-04-17 | Technical Absorbents Ltd | Production of fibre |
| EP1464241B1 (en) * | 2003-04-03 | 2006-10-04 | Hauni Maschinenbau AG | Method for producing a fabric for the production of filters of the tobacco industry and apparatus for the production of a filter rod |
| CN1830340B (en) * | 2005-03-11 | 2011-01-26 | 吴晨晓 | High efficiency tar reducing harm reducing filter tip bar and its production equipment |
| CN101053444B (en) * | 2006-04-14 | 2011-01-26 | 湖南中烟工业有限责任公司 | Cutting method for cigarette cylinder hollow filter tip |
| DE102006049823A1 (en) * | 2006-10-19 | 2008-04-24 | Hauni Maschinenbau Ag | Apparatus and method for processing filter material for cigarette filters or the like |
| DE102009021573A1 (en) * | 2009-05-15 | 2010-11-18 | Hauni Maschinenbau Ag | Material conveying device for use in machine, particularly string machine of tobacco processing industries, has grinding units for cutter for cutting product of tobacco processing industries |
| LT2480100T (en) | 2009-09-23 | 2019-03-12 | Essentra Filter Products Development Co. Pte. Ltd. | Tow cutter |
| CN102534871A (en) * | 2012-01-09 | 2012-07-04 | 湖南大学 | Fiber shearing device |
| CN112425816A (en) * | 2019-08-26 | 2021-03-02 | 上海烟草集团有限责任公司 | Collecting roller of cigarette filter stick forming machine, wire winding processing device and wire winding processing method |
| CN114775115B (en) * | 2022-05-13 | 2024-11-05 | 王小丽 | A method for preparing flame retardant polyamide fiber material |
-
1981
- 1981-07-08 GB GB08121106A patent/GB2101642A/en not_active Withdrawn
-
1982
- 1982-07-05 CA CA000406575A patent/CA1189784A/en not_active Expired
- 1982-07-06 AU AU85659/82A patent/AU8565982A/en not_active Abandoned
- 1982-07-08 BR BR8204034A patent/BR8204034A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8204034A (en) | 1983-07-05 |
| AU8565982A (en) | 1983-01-13 |
| GB2101642A (en) | 1983-01-19 |
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