GB2264855A - Method of separating tobacco particles on a cigarette manufacturing machine, and manufacturing machine implementing such a method - Google Patents

Description

i 1 - 2264855 METHOD OF SEPARATING TOBACCO PARTICLES ON A CIGARETTE

MANUFACTURING MACHINE., AND MANUFACTURING MACHINE IMPLEMENTING SUCH A METHOD The present invention relates to a method of separating tobacco particles on a cigarette manufacturing machine.

On cigarette manufacturing machines, the particles of shredded tobacco are normally fed by gravity from an input feedbox to a substantially horizontal conveyor belt through a carding device, and on the conveyor to a separating unit for separating the light usable tobacco particles from the heavy woody particles mainly consisting of the ribs of the tobacco leaves. The heavy particles are normally allowed to drop into a waste channel, while the light particles are fed by suction to a vertical channel closed at the top by a Buction conveyor belt on which the light particles are deposited to f orm a layer of tobacco f rom which to produce a continuous cigarette rod.

On known units f or separating the light and heavy particles, the output end of the conveyor belt is normally housed inside a chamber communicating at one end with the vertical channel and at the other with the waste channel. The two channels are normally aligned with each other. and a common ascending air current is blown along both for directing the light particles upwards, while the heavy ones drop down against the air current into the waste channel.

The above known method has proved difficult to apply in actual practice, by virtue of requiring highly precise speed adjustment of the ascending air current for ensuring more or less complete removal of the heavy particles while at the same time minimizing rejection of the light particles alongside the heavy ones. That is, as the heavy and light particles are closely bound on reaching the separating unit, a relatively slow air current provides for substantially complete removal of the heavy particles, but only at the expense of a large number of lighter particles as well, whereas too fast an air current provides for directing not only all the light particles but also a certain number of heavy particles on to the suction belt.

The fast air current solution is normally rejected on the grounds that any heavy particles deposited_on the suction belt and consequently incorporated in the continuous cigarette rod tend to pierce the cigarette paper, and form inside the cigarettes low-density portions resulting in tobacco fallout. consequently, the separating units are normally so regulated as to remove substantially all the heavy particles, even at the expense of also rejecting a large number of lighter particles.

It is an object of the present invention to provide a straightforward, low-cost method enabling substantially complete removal of the heavy particles combined with substantially negligible rejection of the light particles, and which, with only relatively minor alterations, may also be implemented on existing machines.

According to the present invention, there is provided a method of separating tobacco particles on a cigarette manufacturing machine, whereby shredded tobacco containing heavy and light particles is fed along a given path to first separating means by which it is subjected to a first separating operation for obtaining, on the one hand, light particles to be supplied directly to user means, and, on the other.. waste material containing heavy particles and leftover light particles; characterized by the fact that said waste material is subjected to a second separating operation inside second separating means, for salvaging, from the waste material,, usable material substaptially consisting of light particles and containing substantially no heavy particles.

According to a preferred embodiment of the above method, the salvaged material is fed to a point along said path upstream from said first separating means.

The present invention also relates to a cigarette manufacturing machine implementing the above method.

According to the present invention, there is provided a cigarette manufacturing machine comprising supply means for feeding shredded tobacco containing heavy and light particles along a given path; first separating means for receiving the shredded tobacco from said supply means, and subjecting the tobacco to a first separating operation wherein said light particles are at least partly separated from a waste material containing said heavy particles, said first separating means presenting a first output for the light particles, and an outlet for unloading said waste material; a nd means for using said light particles, said user means being connected directly to said first output; characterized by the fact that it comprises second separating means having an input connected to said outlet, for salvaging, from said waste material, material substantially consisting of light particles and containing substantially no heavy particles; and a second output for said salvaged material and independent of said first output.

According to a preferred embodiment of the above machine, conveying means are provided for feeding the salvaged material to a point along said path upstream from said first separating means.

- 5 A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Fig.1 shows a schematic section, with parts removed for clarity, of the output portion of a preferred embodiment of the cigarette manufacturing machine according to the present invention; Fig.2 shows a larger-scale section of a detail in Fig.l.

Number 1 in Fig.1 indicates a cigarette manufacturing machine, the output portion of which comprises a shredded tobacco feed unit 2. Unit 2 presents an output element consisting of a substantially horizontal conveyor belt 3 comprising an output pulley 4 located beneath and facing the periphery of a suction roller 5.

Roller 5 and conveyor 3 define an inlet 6 through which unit 2 communicates with a known separating unit 7 (shown only partially) in turn communicating with a substantially vertical upfeed channel 8. channel 8 is closed at the top end by a known conveyor belt 9, which is permeable to air and separates channel 8 from a vacuum chamber 10 communicating with known suction means (not shown) for creating a vacuum inside both chaInber 10 and channel 8.

Separating unit 7 comprises a substantially vertical downfeed waste channel 11 aligned with channel 8 and closed in fluidtight manner at the bottom end by a rotary conveyor element 12 interposed between channel 11 and a catch basin 13, the bottom end of which communicates on one side with an outlet conduit 14. and on the other with a compressed air supply conduit (not shown).

on the roller 5 and conveyor 3 side. channel 11 is defined by a substantially vertical wall 15 having an opening 16 located between inlet 6 and conveyor element 12, and adjustable in size by means of a valve element 17.

Machine 1 also comprises a separating device 18 connected in removable manner to the output end of conduit 14 and defined, as shown in Fig.2, by an input settling unit 19 and a separating unit 20 communicating with each other.

Settling unit 19 comprises a hollow body 21 fitted inside with a filtering wall 22 permeable to air and which divides the inner cavity of body 21 into two chambers 23 and 24. Chamber 23, on top, communicates with a compressed air outlet conduit 25; while chamber 24 communicates laterally with the output of conduit 14 via a hole 26 formed in lateral wall 27 of body 21, and at the bottom with separating element 20 via a channel 28 closed in fluidtight manner by a rotary cpnveyor element 29.

Separating unit 20 comprises a hollow body 30 integral with body 21. substantially in the form of a rectangular parallelepipedon, and having two parallel long lateral walls 31 and 32., the second of which is integral with body 21 and presents, in an intermediate portion, a hole 33 communicating with the output end -of channel 28. Body 30 is closed at the top by a wall 34 substantially perpendicular to walls 31 and 32, and presents a substantially vertical internal dividing wall 35 substantially parallel to walls 31 and 32, extending from the bottom end of body 30, and terminating close to inner surface 36 of wall 34. Wall 35 thus defines, inside body 30, a substantially upside down U-shaped passage defined by two substantially vertical channels 37 and 38 connected by a transverse chamber 39 extending over the top edge of wall 35 and beneath wall 34. More specifically, wall 35 slopes slightly towards wall 31 as of the bottom end of body 30, so that the section of channel 37 increases gradually towards an output conduit 40 connected to the bottom end of body 30, and so that the section of channel 38 increases gradually towards chamber 39 and as of an opening 41 at the bottom end of body 30.

chamber 39 houses a conveyor device 42 located directly over the top end of channel 38, and comprising a cylindrical cage 43 made of mesh or similar filtering material permeable to air, and positioned substaptially horizontally with its longitudinal axis parallel to the top edge of wall 35. Conveyor device 42 also comprises a suction roller 44 housed coaxially inside cage 43. Suction roller 44 comprises a hollow outer cylinder 45 with through radial suction holes, and is rotated with 8 - cage 43., by known drive means (not shown), with its inner cylindrical surface contacting a fixed cylindrical distributor 46. Distributor 46 presents an axial suction channel connected to a suction chamber 47 extending along the outer periphery of distributor 46 and between a generating line substantially facing the top edge of wall 35, and a generating line substantially facing inner surface 36 of wall 34.

cage 43 defines, with inner surface 48 of wall 32, a relatively smallsection passage 49, and, with inner surface 36 of wall 34, a passage 50 controlled by a gravity valve element 51 mounted so as to swing inside chamber 39 to and from a position contacting the outer surface of cage 43 at passage 50.

From the top edge of wall 35 there projects upwards a scraper element 52 tangent to the outer surface of cage 43. so that channels 38 and 37 communicate solely via passages 49 and 50.

As shown in Fig.1, a conveyor 53 is provided beneath conduit 40, for receiving the material fromconduit 40 and preferably feeding it inside machine 1 at a point, along the path of the shredded tobacco inside machine 1, upstream from separating unit 7. In the example shown, conveyor 53 provides for feeding the output material from conduit 40 directly on to conveyor 3.

In actual use, the suction exerted in chamber 10 draws in air through opening 16, through which compressed air may be fed, if necessary, into separating unit 7; and the tobacco particles fed by conveyor 3 into channel 11 through inlet 6 intersect the air current moving upwards from opening 16 towards upfeed channel 8.

The interaction between the ascending air current and the stream of tobacco from inlet 6 detaches the lighter tobacco particles, i.e. those with less kinetic energy, which are directed upwards into channel 8 and on to the underside of belt 9. The heavy particles, on the other hand, normally consisting of ribs and tightly attached lighter particles, continue on to the wall of channel 11 opposite wall 15 in the form of waste material, which drops down channel 11 on to conveyor element 12 by which it is fed into catch basin 13 at relatively slow speed and with practically no kinetic energy.

In connection with the above, it should be pointed out that the speed of the air current fed into separating unit 7 through opening 16 is so regulated by valve element 17 as to eliminate any possibility of ribs being fed on to belt 9, but obviously. only at the expense of rejecting a relatively large quantity of lighter particles together with the ribs.

Inside catch basin 131 the waste material intersects an air current fed into basin 13 by said air supply conduit (not shown), and is fed by the air current and along outlet conduit 14 into chamber 24 of settling unit 19.

- 10 Inside settling unit 19, the waste material, after being separated from the air, which is exhausted through filtering wall 22, chamber 23 and conduit 25, is deposited on to conveyor element 29 by which it is f ed, at relatively slow speed and with practically no kinetic energy, into channel 38 of separating unit 20 of separating device 18.

The suction exerted by suction conveyor device 42 creates a vacuum inside channel 38, thus drawing in outside air through opening 41, which f lows upwards to intercept the waste material from channel 28. By virtue of the upward-flaring design of channel 38, the ascending air current expands and becomes turbulent, thus separating the _ribs in the waste material from the tightly attached lighter particles, which ribs drop down and out through waste opening 41.

The remainder of the waste material, mainly consisting of light particles, is drawn upwards by the ascending air current on to cage 43 of conveyor device 42,, by which it is fed through passages 49 and 50, along the entire arc of chamber 47, and beneath valve element 51, which provides for detaching any accumulated tobacco off cage 43., as well as for cooperating with scraping element 52 for preventing the vacuum in channel 38 from spreading to channel 37.

Downstream from passage 50, the particles adhering to cage 43 are detached by scraper element 52, and drop down channel 37 to form a stream of salvaged material - 11 substantially consisting of light particles, and which flows out of channel 37 through outlet conduit 40, and on to conveyor 53.

In connection with the above. it should be pointed out that, if the air current through separating unit 7 is so regulated as to only remove and supply light particles to belt 9, the air current through separating device 18 is regulated so as to remove as many light particles as possible from the waste material via conveyor device 42, so that only a relatively small percentage of ribs remains in the salvaged material. It is therefore advisable to avoid positioning separating device 18 parallel to separating unit 7 in relation to belt 9, and the salvaged material is preferably used by f eeding it, via conveyor 53, to any point on machine 1 upstream from separating unit 7, to prevent any possibility of ribs or other heavy particles being fed on to belt 9.

Claims (11)

1) A method of separating tobacco particles on a cigarette manufacturing machine (1)0, whereby shredded tobacco containing heavy and light particles is fed along a given path to first separating means (7) by which it is subjected to a first separating operation for obtaining,, on the one hand, light particles to be supplied directly to user means (9), and, on the other, waste material containing heavy particles and leftover light particles; characterized by the fact that said waste material is subjected to a second separating operation inside second separating means (18), for salvaging, from the waste material, usable material substantially consisting of light particles and containing substantially no heavy particles.

2) A method as claimed in Claim 1, characterized by the fact that said salvaged material is f ed to a point along said path upstream from said first separating means (7).

3) A cigarette manufacturing machine comprising supply means (3) for feeding shredded tobacco containing heavy and light particles along a given path;.. first separating means (7) for receiving the shredded tobacco from said supply means (3), and subjecting the tobacco to a first separating operation wherein said light particles are at least partly separated from a waste material containing said heavy particles, said first separating means (7) presenting a first output (8) for the light particles, and an outlet (14) for unloading said waste material; and means (9) for using said light particles, said user means (9) being connected directly to said first output (8); characterized by the fact that it comprises second separating means (18) having an input (26) connected to said outlet (14), for salvaging, from said waste material, material substantially consisting of light particles and containing substantially no heavy particles; and a second output (40) for said salvaged material and independent of said first output (8).

4) A machine as claimed in Claim 3, characterized by the fact that conveyor means (53) are provided for feeding said salvaged material to a point along said path upstream from said first separating means (7).

5) A machine as claimed in claim 3 or 4, characterized by the fact that said second separating means (18) comprise a settling unit (19) for separating said waste material from a conveying air current; and a separating unit (20) for separating said salvaged material from the waste material; conveyor means (29) being mounted in fluidtight manner between sa_id two units (19, 20) for transferring said waste material from the settling unit (19) to the separating unit (20).

6) A machine as claimed in claim 5, characterized by the fact that said separating unit (20) comprises channel means (37, 38, 39) substantially in the form of an upside down U, and in turn comprising an upfeed channel (38) and a downfeed channel (37) having respective adjacent top ends.. and a transverse chamber (39) connecting said top ends; a waste material input (33) in an intermediate portion of the upfeed channel (38); and suctibn conveyor means (42) for creating a vacuum inside said upteed channel (38) and transferring said salvaged material from the upfeed channel (38) to the downfeed channel (37); said second output (40) being formed at the bottom end of the downfeed channel (37); and an air supply inlet and heavy particle outlet (41) being formed at the bottom end of the upfeed channel (38).

A machine as claimed in Claim 6, characterized by the f act that said suction conveyor means (42) are mounted in fluidtight manner through said transverse chamber (39) for confining said vacuum to the upfeed channel (38).

8) A machine as claimed in Claim 6 or 7, characterized by the fact that said suction conveyor means (42) comprise a suction roller (44) located over the top end of the upfeed channel (38); and filtering means (43) permeable to air and arranged about the suction roller (44).

9) A machine as claimed in any one of the foregoing Claims from 6 to 8, characterized by the fact that said upfeed channel (38) is flared towards said transverse chamber (39).

A 10) A method of separating tobacco particles on a cigarette manufacturing machine, substantially as described and illustrated herein with reference to the accompanying drawings.

11) A machine implementing the method as claimed in claim 10. and substantially as described and illustrated herein with reference to the accompanying drawings.