This application claims the benefit of Italian Patent Application No. BO2012A 000106, filed Mar. 5, 2012, the entirety of which is hereby incorporated by reference.
The present invention relates to a method and a machine for producing paperless filter rods for smoking articles.
It is known in the tobacco industry to make paperless filter rods using a continuous tape of filtering material, normally cellulose acetate, which is continuously fed through an impregnation station, at which the tape is impregnated with a hardening substance, normally triacetin, and is then transformed, by means of blowing air, into a generally cylindrical tow band, which is caused to advance along a longitudinal through channel of a forming beam comprising a first portion, in this case a stabilization portion, and a second portion, in this case a drying portion. Along the first portion, the hardening substance in the tow band is caused to react by means of blowing steam, normally water steam; while, along the second portion, the tow band, previously moistened by the steam, is dried so as to come out of the forming beam in the form of a continuous rod having a determined stable section and relatively high axial rigidity.
This continuous rod is hence fed, again with continuous motion, to a cutting station to be cut into filter segments of determined length.
The advancing of the tow band along the longitudinal channel of the forming beam is normally obtained by means of a loop conveyor defined by a porous conveyor belt that is permeable to the steam, and comprising a transport stretch extending along the longitudinal channel of the forming beam. The longitudinal channel has a variable section shaped so as to act on the conveyor belt so as to deform it crosswise and cause it to take a tubular configuration wound about the tow band to define, about the tow band, a relatively rigid armature, which on the one hand is permeable to steam and, on the other, tightens about the tow band so as to both give it the determined constant shape of a cross section, and to ensure an axial dragging coupling between tow band and conveyor belt.
Instead, downstream from the forming beam and the mentioned conveyor belt, the newly-formed continuous rod is push advanced, and this type of advancing is only made possible by the fact that, as previously mentioned, the continuous rod is axially rigid.
The need for the continuous rod coming out from the forming beam to be rigid, that is perfectly stabilized and dried, has greatly affected the methodologies used to date for making paperless filter rods and has led to making machines in which, as soon as the mentioned tow band enters the longitudinal channel of the forming beam, it is radially hit by a steam flow supersaturated with a relatively high water flow and content and a relatively low speed; the drying portion is relatively long; and the advancing speed of the loop conveyor is relatively low.
The length of the forming beam and the reduced advancing speed of the loop conveyor allow each section of the tow band to remain in the forming beam for a relatively long time and, in all cases, enough to firstly allow the steam to reach the core of the tow band, due to capillary effect, and cause all the hardening substance to react, and, secondly, the tow band to completely dry as it advances along the drying portion.
Finally, the use of the methodologies known to date has allowed good quality paperless filter rods to be obtained, but with relatively low production speeds.
It is the object of the present invention to provide a method for making paperless filter rods for smoking articles, which allows the quantity of water in the steam flow to be significantly reduced and the production speed to be significantly increased without negatively affecting the quality of the product.
In one aspect, the invention can be a method for producing paperless filter rods for smoking articles, comprising: feeding a tow band of hardening-material-impregnated filtering material, onto porous conveying means extending along a forming channel of a forming beam comprising a stabilizing first portion and a drying second portion; advancing the conveyor means and the tow band along the forming channel; blowing steam through the conveyor means and the tow band as they advance along the first portion to cause the hardening material to react; blowing air through the conveyor means and the tow band as they advance along the second portion to dry the tow band previously moistened by the steam to obtain a continuous paperless rigid rod filter; and feeding the continuous rod coming out from the forming beam to a cutting means to cut the rod crosswise into filter segments of a predetermined length; wherein steam blowing is performed at a number of stabilization stations arranged in series along the first portion; and wherein at each stabilization station, the steam is fed into an accumulation chamber surrounding the forming channel and communicating therewith through an annular nozzle extending on a transverse plane to the forming channel and having a constant width, measured along an axis of the forming channel, of 0.3 to 0.9 mm.
In another aspect, the invention can be a machine for producing paperless filters for smoking articles, the machine comprising a forming beam comprising a stabilizing first portion and a drying second portion and having a forming channel extending along an axis between an input and an output; porous conveying means extending along the forming channel and driven to move along the forming channel in a determined direction, parallel to said axis; feeding means to feed a hardening-material-impregnated filtering material tow band onto the conveying means and upstream from said inlet; stabilizing means arranged along the first portion for injecting steam through the conveying means and the tow band for causing the hardening material to react; drying means arranged along the second portion for blowing air through the conveyor means and the tow band for drying the tow band previously moistened by the steam and to obtain a continuous paperless rigid filter rod; and a cutting device disposed downstream from said outlet in the feed direction to cut the continuous rod crosswise into filter segments of a determined length; wherein the stabilizing means comprises at least two stabilization stations arranged in series along the first portion; and wherein each stabilization station comprises an accumulation chamber surrounding the forming channel; feeding means to feed steam to the accumulation chamber; and an annular nozzle to put the accumulation chamber into communication with the forming channel; the annular nozzle being arranged on a plane extending crosswise to the forming channel and having a constant width, measured along said axis, of 0.3 to 0.9 mm.
The invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting exemplary embodiment thereof, in which:
The following detailed description of the present invention shows a specified embodiment of the present invention and will be provided with reference to the accompanying drawings. The embodiment will be described in enough detail that those skilled in the art are able to embody the present invention. It should be understood that various embodiments of the present invention are different from each other and need not be mutually exclusive. For example, a specific shape, structure and properties, which are described in this disclosure, may be implemented in other embodiments without departing from the spirit and scope of the present invention with respect to one embodiment. Also, it should be noted that positions or placements of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not intended to be limited. If adequately described, the scope of the present invention is limited only by the appended claims of the present invention as well as all equivalents thereto. Similar reference numerals in the drawings designate the same or similar functions in many aspects.
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Machine 1 comprises an inlet unit 2, of known type, adapted to produce a tape 3 of filtering material, normally cellulose acetate, moistened with a hardening fluid, normally triacetin; a rod forming unit 4, arranged in series to the inlet unit 2 and adapted to receive tape 3 and to cause the hardening material to react to transform tape 3 into a continuous paperless axially rigid rod filter 5; and a cutting device 6, normally a rotating cutting head of known type, arranged downstream of the rod forming unit 4 in a feed direction 7 of tape 3 and of rod 5, and adapted to cut rod 5 crosswise into paperless filter segments (not shown).
The rod forming unit 4 comprises a base 8 limited at the top by a flat and substantially horizontal panel 9, which supports a pneumatic inlet device 10, of known type, adapted to receive tape 3 saturated with hardening material, to shape tape 3 crosswise so as to transform it into a moist, generally cylindrical tow band 11 and to advance the tow band 11 in the feed direction 7. Panel 9 also supports a forming beam 12 aligned with the pneumatic device 10 in the feed direction 7 to receive the tow band 11 and transform it into the continuous rod 5.
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Finally, the pneumatic device 10 comprises a funnel 19, which is connected to an outlet end of duct 13 and is provided with side holes for releasing the air fed through the holes 18. Funnel 19 is also provided with a vertex opening 20 facing the forming beam 12, and, rests on an inlet portion of a transport stretch 21 of a closed loop conveyor belt 22 made of a porous material which is permeable to steam.
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Also two further grooves 40 are obtained along the upper surface 37, which are arranged on opposite sides of groove 38, are parallel to groove 38 and accommodate respective gaskets 41 adapted to ensure a fluid-tight coupling between the covers 27 and 28 and the lower plate 25.
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The intermediate portion 53 is internally threaded and defines the case of a control valve 56 of the steam flow entering the lower chamber 46, comprising a threaded slider 57 coaxial to the intermediate portion 53 and coupled with the internal threading thereof to move axially along duct 50 between an extracted position, shown in
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Machine 1 is regulated, in use, by a control unit 74 capable of controlling, among other things, the feed speed of tape 3, the control valves 56, the flow, temperature and saturation of the steam fed to the collector 64, and the vacuum pump 73.
The general operation of machine 1 does not differ from the general operation of a known machine of the same type, and does not require further explanation.
What does instead require a particular explanation is how the exposure is controlled, in machine 1, of the tow band 11 to the action of the steam along the stabilization portion 29 of the forming beam 12, while considering that:
In known machines, steam is normally fed to the tow band by means of a feed duct ending with a nozzle arranged radially with respect to the tow band. Thus, there is a need for relatively large steam flows (i.e. with significant transport of water drops) and relatively long exposure times of the steam and drying times (i.e. relatively reduced advancing speed of the tow band) to allow both the steam to permeate the entire section of the tow band, and, the drying of the moist points.
In each stabilization station 45 in machine 1, the slits 61 and 62 define, as a whole, an annular nozzle capable of shooting an annular steam jet which, fed steam being equal, at least halves the permeation times of the tow band 11. Achieving the result is promoted by the fact that the mentioned annular nozzle has a relatively reduced passage gap (0.3 and 0.9 mm and preferably equal to about 0.7 mm), to which, steam flow being equal, an outflow speed of the steam corresponds and therefore, a relatively high penetration capacity.
Furthermore, the feeding of the steam along the stabilization portion 29 of the forming beam 12 is divided among a plurality of stabilization stations 45, with the consequence that the steam flow and therefore, the ability of the steam to transport micro-drops of water, are drastically reduced.
Lastly, it is worth pointing out that the steam at each stabilization station is not directly fed to the mentioned annular nozzle, but through an accumulation chamber (lower chamber 46 and upper chamber 47).
The presence of this accumulation chamber, combined with the fact that the transversal dimensions of the mentioned annular nozzle and the steam flow through it are, in all, cases, greatly reduced, result in most of the steam inside the mentioned accumulation chamber remaining under substantially static conditions, and that only that part of this steam which is located in the immediate vicinity of the mentioned annular nozzle undergoes a sudden acceleration which, by inertia, only involves the unsaturated (lighter) part of the steam and not the micro-drops of water possibly suspended therein.
The final result is that a “blade” jet of practically dry steam comes out of the mentioned annular nozzle, and activates the hardener, but moistens the tow band 11 in an insignificant manner thus shortening the drying times and making possible advancing speeds of the tow band 11 almost double of those detectable in known machines of the same type as machine 1.
With regard to the above, it is worth pointing out that many tests performed on machine 1 have shown that, if dividing the steam flow in several stabilization stations 45 (up to eight stabilization stations 45 arranged in series along the forming beam 12) has proven to be an accessory feature tending to improve the final results (if necessary, use of only part of the stabilization stations 45 may be sufficient), the presence of mentioned annular nozzle, the transversal dimensions (width of slits 61 and 62) of the annular nozzle and the presence of accumulation chamber (chambers 45 and 46) for feeding the annular nozzle have proven to be “critical” features. For example, simply eliminating the accumulation chamber and/or using slits 61 and 62 that are just one or two tenths wider with respect to the indicated range of variation (0.3-0.9 mm) results in the predetermined results no longer being achievable.
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The inner-shaping device is defined by a mandrel 75, which is equal in diameter to the one of the axial hole to be obtained, is substantially “omega” shaped and comprises two end portions 76 and 77 which are coaxial to each other and to axis A, and a curved intermediate portion 78 with concavity facing downwards. The end portion 76 is blocked inside a hole 79 obtained coaxially to axis A through the foot of the support bracket 15 of duct 13; the end portion 77 engages, with radial clearance, an inlet portion, normally limited to the first two or three stabilization stations 45, of the forming channel 36; while the intermediate position 78 comprises an ascending length 80, which is joined to the end portion 76 and penetrates into duct 13 through a specific slit by being arranged on the course followed by the tow band 11 coming out from duct 13, an intermediate length 81, which is parallel to axis A and is arranged inside funnel 19, and a descending length 82, which is arranged inside funnel 19 and joins the intermediate length 81 to the end portion 77.
In use, by coming in contact with the ascending length 80 first, and then with the intermediate length 81, the tow band 11, which is moistened and plastically deformable, deforms into a U shape, with a concavity facing downwards, astride of mandrel 75. When the tow band 11 reaches the descending length 82, the two arms of the U join together below mandrel 75 due to the effect of the pneumatic compression that the tow band 11 undergoes at opening 20. The tow band 11 takes its original shape again at the inlet of the forming channel 36, and perfectly envelopes the end portion 77 of mandrel 75.
If the inner-shaping device defined by mandrel 75 is present, preferably only the stabilization stations 45 crossed by the end portion 77 are activated, since there is a possibility that the axial hole just made through the tow band 11 closes if any one stabilization station 45 were activated downstream the end portion 77.
According to a different variation not disclosed, tape 3 is axially cut into two semi-tapes, each of which is fed to a respective pneumatic inlet device 10 to produce a semi-tow band. These two pneumatic inlet devices 10 are arranged tilted with respect to each other, converge one towards the other and towards the inlet station 35 and are arranged one above and the other below a mandrel or straight core, which, is coaxial to axis A, penetrates into the forming channel 36 for a determined length and is arranged between the two semi-tow bands, which are deformed by the conveyor belt 22 to form a tubular tow band 11 which is perfectly wound about the mentioned mandrel.
In the above-mentioned variation not disclosed, half cutting tape 3 is advantageous, as compared to using two separate, smaller tapes, because this involves using a single inlet unit 2; furthermore, use of a straight mandrel to make a tubular tow band 11 allows the same alternate axial movements and/or rotary movements—which tend to prevent any adhesion of the tow band 11 to the mandrel—about axis A to be given to the mandrel with extreme ease.
The features, structures and effects and the like described in the embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects and the like provided in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, contents related to the combination and modification should be construed to be included in the scope of the present invention.
Although embodiments of the present invention were described above, these are just examples and do not limit the present invention. Further, the present invention may be changed and modified in various ways, without departing from the essential features of the present invention, by those skilled in the art. For example, the components described in detail in the embodiments of the present invention may be modified. Further, differences due to the modification and application should be construed as being included in the scope and spirit of the present invention, which is described in the accompanying claims.
Number | Date | Country | Kind |
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BO2012A 000106 | Mar 2012 | IT | national |