EP1917870A2

EP1917870A2 - A machine manufacturing filters for tobacco products

Info

Publication number: EP1917870A2
Application number: EP07119418A
Authority: EP
Inventors: Marco Righetti; Armando Turrini; Leonardo Balletti
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 2006-10-31
Filing date: 2007-10-26
Publication date: 2008-05-07
Anticipated expiration: 2027-10-26
Also published as: ITBO20060749A1; CN101171977B; DE602007012189D1; CN101171977A; EP1917870B1; EP1917870A3

Abstract

A filter maker for tobacco products is equipped with a feed system (2) supplying at least one continuous stream (100) of filter tow, a duct (3) along which the filaments of the continuous stream (100) are directed and gathered into a cylindrical rope or bundle (101), a nozzle (4) at the end of the duct (3) from which the bundled filter material emerges as a continuous rod (102), and a cutter (7) by which the rod (102) is divided into filter plugs. The bundle (101) is transported along the duct (3) with the assistance of pressurized air supplied by a feed system (8) that comprises an inlet port (9) admitting a flow of compressed air, an annular passage (11) located between the inlet port (9) and the bore of the duct (3), and an equalizing stage (12) placed between the inlet (9) port and the annular passage (11), by which the flow of air directed into the duct is rendered uniform.

Description

The present invention relates to a machine for manufacturing filters applicable to tobacco products, and in particular to cigarettes.
The manufacture of cigarette filters generally involves processing a continuous stream of filter material, such as cellulose acetate, which is drawn from a compacted bale.
In practice, the continuous stream of filter material consists in a high number (thousands) of continuous filaments.
Prior art manufacturing methods include a step of feeding the stream along a predetermined path through processing stations, where it is first stretched lengthwise and crosswise, and then wetted with chemical additives, typically triacetin.
At a further station located downstream of the aforementioned processing stations, the filter material is gathered into a continuous rope or bundle of cylindrical appearance by respective shaping means.
In certain prior art embodiments, the shaping means appear as a funnel-like duct into which the continuous stream is introduced, carried forward by a flow of air, its transverse dimension reducing gradually to the point that the filaments are drawn into a rope, or bundle, presenting a cross section substantially the same as that of a cigarette.
Once formed, the bundle passes through a further processing station where it is wrapped by degrees in a continuous strip of paper material, forming a continuous filter rod that will then be divided up into single plugs by a rotary cutter device.
The aforementioned flow of air that carries the stream through the funnel-like duct is admitted by way of an annular passage, connecting the duct to a source of pressurized air.
The annular passage is inclined relative to the feed direction of the continuous bundle, in such a manner that the pressurized air admitted via the passage will enter the duct and invest the outer surface of the bundle of filter material, assisting its progress toward the outlet of the duct.
It has been observed that in prior art machines, however, the continuous bundle is not transported uniformly through the funnel-like duct.
In effect, the air enters the annular passage at one or more localized points, with the result that the flow investing the continuous bundle as it forms internally of the duct is not homogeneous.
As a consequence of the drawback in question, the bundle is subject to asymmetrical thrust components that will translate into poor production stability, that is to say inconsistencies in the filtration properties presented by a given continuous bundle.
The object of the present invention is primarily to provide a machine for manufacturing filters applicable to tobacco products, such as will be unaffected by the drawback mentioned above.
In particular, the object of the invention is to provide a machine manufacturing filters for tobacco products that will convey the continuous bundle of filter material in a uniform manner.
A further object of the present invention is to provide a machine manufacturing filters for tobacco products, having the attributes needed to ensure good production stability.
The stated objects are realized according to the invention in a machine for manufacturing filters applicable to tobacco products, as characterized in one or more of the appended claims.
The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:

figure 1 is a schematic illustration of a machine manufacturing filters for tobacco products, in accordance with the present invention;
figure 2 illustrates a detail of the machine in figure 1, viewed in perspective with certain parts omitted better to reveal others;
figure 3 illustrates the detail of figure 2 in a section on III-III, viewed in a first operating configuration;
figure 4 is the section of figure 3, illustrating a second operating configuration.

With reference to figure 1, numeral 1 denotes a machine for manufacturing filters applicable to tobacco products, embodied in accordance with the present invention.
Whilst the following specification describes a single track filter maker, the various elements are referable equally to a twin track machine.
The machine 1 comprises feed means 2 supplying a continuous stream 100 of filter material, a duct 3 along which the continuous stream 100 of filter material is directed and formed into a cylindrical bundle 101 (illustrated partially in figure 3), a nozzle 4 at the end of the duct 3, from which the bundle emerges as a continuous rod 102, a garniture section 5 along which the continuous rod 102 is enveloped in a strip 6 of paper plugwrap material, and means 7 by which the wrapped rod is cut into single filter plugs, also feed means 8, illustrated in figures 2, 3 and 4, supplying a flow of air by which the bundle 101 forming within the duct 3 is subjected to an axial pushing force.
Referring in particular to figures 2, 3 and 4, the feed means 8 comprise an inlet port 9 admitting the flow of air, associated with a fitting 10 for connection to a compressed air supply line (not illustrated), and an annular passage 11 located between the air inlet 9 and the bore of the duct 3. For the purposes of the present invention, the annular passage affords an air gap of which the flow section is significantly small compared to the length of the selfsame gap as measured along the flow-through direction.
In the example of figures 2 to 4, accordingly, the proportions of the annular passage 11 are not to scale, and in particular, the width of the gap admitting the flow of air is augmented in order to illustrate the passage 11 to best advantage.
Air is conveyed from the inlet port 9 toward the duct 3 in a direction substantially orthogonal, or ideally inclined, relative to the feed direction X followed by the bundle 101 along the duct 3. Also, the air inlet port 9 is not of annular geometry like the passage 11, but located at a single point on the periphery of the duct 3, or in any event a limited number of points (see figures 2 to 4).
To advantage, the feed means 8 supplying the flow of air comprise equalizing means 12, preferably of a type designed to induce a pressure drop, located between the inlet port 9 and the annular passage 11 and serving to ensure the supply of a uniform flow of air into the passage 11.
Accordingly, the continuous bundle 101 forming within the duct 3 is invested by a homogeneous flow of air such as will assist its progress along the selfsame duct 3, thus favouring a good stability of production (with filtration properties maintained constant along the full length of the bundle).
In particular, the equalizing means 12 comprise an expansion chamber 13 located between the inlet port 9 admitting the flow of compressed air, and the annular passage 11.
The expansion chamber 13 is annular in shape and fully encircles the innermost part of the duct 3, that is to say the tube 14 internally of which the continuous bundle 101 advances.
The expansion chamber 13 is also connected to a distribution chamber 15, presenting a wall 16, by way of which the flow of air is directed into the annular passage 11.
More exactly, and as illustrated in figures 2, 3 and 4, the compressed air inlet port 9 communicates directly with the expansion chamber 13, whilst the distribution chamber 15 is located downstream of the expansion chamber 13, presenting an annular configuration and encircling the tube 14 in like manner to the upstream chamber 13.
To advantage, the aforementioned wall 16 of the distribution chamber 15, interfacing with the expansion chamber 13 and intercepting the flow of air, presents a plurality of holes 17 by which the flow of air about to enter the annular passage 11 is subjected to a further equalizing action.
In practice, the holes 17 serve to induce further pressure losses in the flow of air, the effect of which being to equalize the distribution of both the velocity component and the pressure component in the flow directed through the annular passage 11 and onto the continuous bundle 101.
As discernible in figures 3 and 4, the annular passage 11 is inclined in relation to the feed direction X followed by the bundle 101 along the duct 3, and in particular, inclined at an angle such that the flow of air will be directed as tangentially as possible onto the bundle 101.
The annular passage 11 is created between two half sections 18 and 19 making up the duct 3.
In particular, the first half-section 18 of the duct 3 presents a cavity 20 establishing a first segment of the aforementioned tube 14 through which the bundle 101 is directed.
The cavity 20 is of substantially convergent funnel-like geometry, and thus easily associated with the feed means 2 from which the continuous stream 100 of filter material is received.
A cavity 20 of the type in question could be embodied as a succession of rectilinear conical duct portions joined suitably one to the next, or alternatively, with a continuous profile of which the geometry appears substantially parabolic or comparable to cubic splines or splines of higher order.
The second half-section 19 of the duct 3 is associated stably with the first half-section 18 and translatable relative thereto along an axis parallel to the feed direction X followed by the cylindrical bundle 101 forming in the duct, as will be made clearer in due course.
The first and second half- sections 18 and 19 present respective annular surfaces denoted 21 and 22, breasted one with another and inclined relative to the aforementioned feed direction X of bundle 101.
The two annular surfaces 21 and 22 in question combine operationally to delimit a main portion of the passage 11.
More exactly, and as emphasized pictorially in figures 2 to 4 of the drawings, the two inclined annular surfaces 21 and 22 make no contact, but are distanced slightly one from another.
Advantageously, the distance separating the two inclined annular surfaces 21 and 22 can be adjusted by translating the second half-section 19 relative to the first half-section 18, so as to widen or narrow the flow section afforded by the passage 11: see figure 3, for example, where the flow section of the passage 11 is at minimum, or figure 4, where the flow section is at maximum.
To enable the aforementioned relative translatory motion between the two half- sections 18 and 19, the second half-section 19 is aligned and associated coaxially with the first half-section 18 by way of suitable coupling means, which in the preferred embodiment illustrated are embodied as respective screw threads 23.
Thus, rotating the second half-section 19 about an axis coinciding with the feed direction X of the bundle 101, this same second half-section 19 can be distanced from the first half-section 18, and the flow section of the passage 11 widened.
Importantly, the flow equalizing means 12, and more precisely the expansion chamber 13 and the distribution chamber 15, are associated permanently with the first half-section 18 and therefore remain stationary during the movement by which the flow section of the annular passage 11 is adjusted.
Moreover, since only the second half-section 19 of the duct is repositioned to widen or narrow the flow section of the annular passage 11, there is no risk that traces of chemical compounds, utilized to treat the continuous stream 101 of filter material upstream of the duct 3, will be released during the operation of adjusting the passage 11.
In effect, the second half-section 19 is located downstream of the first half-section 18, as already mentioned, and coupled directly to the nozzle 4 from which the bundle 101 emerges.
The first half-section 18 presents a sleeve 24 in which the second half-section 19 is insertable and on which an aforementioned coupling thread 23 is formed. The outer surface of the sleeve 24 presents a set screw 25 passing through the sleeve 24 wall, by which the second half-section 19 is engaged and locked in the selected angular position.
To rotate the second half-section 19 relative to the first half-section 18, accordingly, it suffices to loosen the set screw 25, whereupon the second half-section 19 can be turned one way or the other by means of drive holes 26 located in the end face.
To advantage, the terminal portion of the annular passage 11 is incorporated directly into a portion of the aforementioned tube 14 coinciding with a substantially cylindrical cavity 27 afforded by the second half-section 19.
More particularly, the portion of the tube 14 afforded by the second half-section 19 presents a plurality of grooves 28 extending parallel to the feed direction X of the bundle 101, also parallel one with another and distributed circumferentially around the tube 14.
Accordingly, and to advantage, even in the event that the alignment of the bundle 101 of filter material should be less than perfectly symmetrical on entering the duct 3, and more especially the tube 14, the grooves 28 will ensure that the flow of air continues to invest the entire surface of the bundle 101 and thus cause the material to advance correctly.
In addition, by favouring an axial orientation of the air flow into the tube 14, the grooves 28 also function actively as flow guides.
The objects stated at the outset are realized in accordance with the invention.
In effect, the equalizing means ensure that the pressure and velocity of the air flowing into the annular passage and destined to invest the bundle gathering in the duct will be, to all intents and purposes, uniformly distributed around the entire annular periphery of the passage inlet section.
In particular, the function of the expansion chamber and the distribution chamber is to handle the flow of air from the inlet port to the annular passage in such a way that it will be rendered uniform and without appreciable variations or imbalances in pressure and velocity.
In this way, even utilizing just the one inlet port, or at all events a limited number of inlet ports, any asymmetrical distribution of pressure and velocity components in the air flow, considered in relation to the inlet section of the annular passage, is significantly attenuated, so that the flow of air will present substantially the same pressure and velocity characteristics when passing both through the portion of the passage located in close proximity to the inlet port and through the portion of the passage located farthest from the inlet port.
This ensures that the pressure and velocity of the air flow ultimately investing the rope or bundle of filaments forming along the duct will be substantially uniform around the entire periphery of the bundle, thereby guaranteeing that the bundle advances correctly and maintaining good production stability.

Claims

A machine manufacturing filters for tobacco products, comprising
- feed means (2) supplying at least one continuous stream (100) of filter material,

- a duct (3) along which the continuous stream (100) is directed and gathered into a cylindrical rope or bundle (101) of such filter material,

- a nozzle (4) at the end of the duct (3) from which the bundled filter material emerges as a continuous rod (102),

- cutting means (7) by which the rod (102) is divided into discrete filter plugs, and

- feed means (8) supplying a flow of air by which the gathering bundle (101) is forced axially along the duct (3), comprising an inlet port (9) admitting the flow of air and an annular passage (11) located between the inlet port (9) and the bore of the duct (3),
characterized
in that the feed means (8) supplying a flow of air comprise equalizing means (12) by which the flow of air located between the inlet (9) port and the annular passage (11) is rendered uniform.
A machine as in claim 1, wherein flow equalizing means (12) comprise an expansion chamber (13) in fluid communication with the inlet port (9) admitting the flow of air and with the annular passage (11).
A machine as in claim 2, wherein the expansion chamber (13) is annular, and placed in direct communication with the air flow inlet port (9).
A machine as in claim 2 or claim 3, wherein flow equalizing means (12) further comprise a distribution chamber (15) located between the expansion chamber (13) and the annular passage (11) and serving to bring about a uniform distribution of the flow of air directed from the expansion chamber (13) to the annular passage (11).
A machine as in claim 4, wherein the distribution chamber (15) is annular and comprises a wall (16) furnished with a plurality of holes (17) offered directly to the expansion chamber (13), serving to equalize the flow of air entering the distribution chamber (15).
A machine as in claim 5, wherein the distribution chamber (15) is placed in direct communication with the annular passage (11).
A machine as in claim 1, wherein the duct (3) comprises a first half-section (18) and a second half-section (19) disposed coaxially with and engaging one another, presenting respective annular surfaces (21, 22) inclined relative to a feed direction (X) followed by the gathering bundle (101) and combining to create at least a part of the annular passage (11).
A machine as in claim 7, wherein the second half-section (19) comprises a plurality of grooves (28) presented by a wall of a tube (14) afforded by the duct (3), through and along which the bundle (101) is directed and gathered, and establishing a terminal part of the annular passage (11).
A machine as in claim 7, wherein the second half-section (19) is capable of movement relative to the first half-section (18) in a direction parallel to the feed direction (X) followed by the bundle (101), to the end of increasing or reducing the flow section afforded by the annular passage (11).
A machine as in claim 9, wherein flow equalizing means (12) are embodied integrally with the first half-section (18).
A machine as in claim 10, wherein the first half-section (18) comprises a cavity (20) presenting a substantially convergent funnel-like appearance, through and along which the bundle (101) is directed and gathered, directed at one end toward the feed means (2) supplying the filter material, and toward the nozzle (4) at the opposite end.
A machine as in claim 11, wherein the cavity (20) appears as succession of rectilinear conical duct portions joined one to the next.
A machine as in claim 11, wherein the cavity (20) presents a continuous and streamlined profile of substantially parabolic geometry, or comparable to cubic splines or splines of higher order.
A machine as in claim 9, wherein the second half-section (19) is associated movably with the first half-section (18) by way of a screw-threaded coupling (23).