Method and unit for supplying a cigarette manufacturing machine

Abstract: A method and unit (1) for supplying a cigarette manufacturing machine (2), whereby a stream (52) of shredded tobacco (3) is supplied to at least one suction conveyor belt (4) by traveling along an upflow output portion (11) of a supply path (9), an input portion (10) of which communicates, at a junction (12), with the output portion (11) and with a basin (39) into which heavy particles (44) in the tobacco fall; the stream (52) of tobacco, as it travels along the input portion (10), being stratified by an air jet directed substantially crosswise to the traveling direction (33) of the stream (52), so that, on reaching the junction (12), the heavy particles (44) in the stream (52) are located on the side of the stream (52) facing the basin (39).

Description: The present invention relates to a method of and a unit for supplying a cigarette manufacturing machine according to claims 1 and 4 which are delimited against the prior art as known e.g. from DE-A-42 42 325. In cigarette manufacturing machines of the type described, for example, in Patent Applications DE OS 42 40 459, DE OS 42 42 325, and in US Patent 4,729,388, shredded tobacco is normally fed from an input feedbox to a box body in which a carding unit feeds it to the input portion of a supply path. This comprises an upflow output portion closed at the top by one or more conveyor belts permeable to air, and is connected at the bottom to said input portion at a junction where the path communicates with a catch basin. An upflowing air current, at least partly produced by suction through said conveyor belt, blows the light parts of the tobacco, comprising powder and relatively minute shreds, along the output portion of the supply path, while any heavier, e.g. woody, parts drop by force of gravity into the catch basin. In general, however, only a small part of the material falling into the catch basin is actual waste. That is, the actual waste particles are mixed with the lighter particles in the stream of tobacco fed to the output portion, and, as they fall into the basin, travel through and take part of the stream of lighter particles with them in the form of lumps. In known cigarette manufacturing machines, every attempt has been made to separate the waste from the good material inside the basin and feed the salvaged material to the output portion, for which purpose, highly complex catch basins or separating devices have been devised (DE OS 42 40 549, US 4,729,388, US 4,618,415, EP 361,815, DE OS 42 42 325) wherein air jets of different strengths and directions provide for unraveling the lumps and separating the light parts from the waste. The above solution, however, presents several drawbacks, due to the unreliability with which the light and heavier parts are separated inside the basins or separating devices, which separation varies as a function of a relatively large number of parameters relative to the type and condition of the tobacco. For example, the damper the tobacco is, the more strongly the particles tend to cling to one another, and the harder the lumps are to unravel. In view of the drawbacks involved, it has therefore been decided that the only way of effectively separating the light particles from the heavy waste particles is to prevent the lumps from forming in the first place, by forming, upstream from the output portion, a stratified stream of tobacco in which the heavy particles are already separated from the light ones and may therefore be removed without taking the light particles with them. This has been achieved by accelerating the stream of tobacco in the traveling direction along the input portion of the supply path by means of a mechanical (e.g. US 4,484,589) or pneumatic (e.g. GB 2,279,862) hurling device, so as to form a jet of tobacco, which, as it settles on a conveyor belt, forms a stratified stream with the heavy particles on top. This solution also presents drawbacks, however, due to the heavy particles, prior to removal, migrating through the stratified stream and so mixing once more with the light particles. It is an object of the present invention to provide a supply method designed to overcome the aforementioned drawbacks and enable effective separation of the heavy waste particles from the light particles in a stream of tobacco. According to the present invention, there is provided a method of supplying a cigarette manufacturing machine, the method comprising the steps of feeding a stream of shredded tobacco to at least one conveyor belt along a supply path comprising an upflow output portion, and an input portion communicating, at a junction, with the output portion and with a basin into which the heavy particles in the stream of tobacco fall; and stratifying the stream of tobacco, as it travels along the input portion, to form a stratified stream comprising layers of heavy particles and layers of light particles adjacent to each other; characterized in that said stratification is achieved by so feeding the stream of tobacco that it presents a first given traveling direction at a given point along said input portion; forming, at said given point, a jet of tobacco traveling in said first direction; deflecting the jet of tobacco in a second direction substantially crosswise to said first direction; and causing the jet to rain down onto a surface defining a portion of said input portion. Being deflected to a lesser extent as compared with the light particles, the heavier particles in the jet therefore tend to land on said surface upstream from the light particles, thus forming, on the surface, a stratified stream in which the heavy particles are positioned stably beneath the light particles, and therefore drop into the basin without taking the light particles with them. The present invention also relates to a unit for supplying a cigarette manufacturing machine. According to the present invention, there is provided a unit for supplying a cigarette manufacturing machine, the unit comprising guide means for guiding a stream of shredded tobacco comprising heavy waste particles, the guide means defining a path along which to supply the stream to at least one conveyor belt, and the path comprising an upflow output portion, an input portion, and a junction connecting the input and output portions; a basin into which the heavy particles fall, the basin communicating with the path at said junction; hurling means located at a given point along said input portion, and for forming a jet of tobacco traveling in a first direction; and a surface defining a portion of said input portion, and for receiving said jet; the unit being characterized by also comprising deflecting means, preferably pneumatic deflecting means, located between said given point and said surface, and for deflecting said jet in a second direction substantially crosswise to said first direction. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic, partially sectioned side view of a preferred embodiment of the supply unit according to the present invention; Figure 2 shows a larger-scale view of a detail in Figure 1. Number 1 in Figure 1 indicates a supply unit forming part of a cigarette manufacturing machine 2, and for supplying shredded tobacco 3 to a known wrapping unit (not shown) of machine 2 by means of two known conveyor belts 4 permeable to air and by which tobacco 3 is retained by suction and fed to said wrapping unit (not shown). Unit 1 comprises an input feedbox 5 for feeding shredded tobacco 3 into a box body 6 and onto a conveyor belt 7, which feeds tobacco 3 to a carding unit 8 housed inside box body 6. Carding unit 8 feeds tobacco 3 onto a supply path 9 extending between box body 6 and the bottom surface of conveyor belts 4, and comprising an input portion 10 and an output portion 11 communicating with each other at a junction 12. Input portion 10 comprises a dropdown channel 13, the top end of which communicates with the output of box body 6, and the bottom output end of which communicates with a substantially cylindrical-section distribution chamber 14 forming part of input portion 10. As shown more clearly in Figure 2, chamber 14 is defined by a substantially L-shaped plate 17, and by a top wall 15 presenting a central through channel 16 with a substantially vertical axis and defining the bottom end of channel 13. Plate 17 is connected integral with a lateral edge of wall 15, and comprises a substantially vertical top portion 18 defining the rear wall of chamber 14, and a bottom portion 19 sloping slightly upwards in direction 20 from the bottom end of portion 18 and defining the bottom wall of chamber 14. The free end of portion 19 and the lateral edge of wall 15 opposite that connected to plate 17 define an axial lateral opening 21 of chamber 14. Chamber 14 houses, at least partially, a hurling unit 22 comprising a known powered conveyor roller 23 presenting a number of radial teeth 24, housed inside chamber 14 directly beneath channel 16, and rotating, anticlockwise in Figures 1 and 2, about an axis 25 perpendicular to the Figure 2 plane and substantially coincident with the axis (not shown) of chamber 14. Hurling unit 22 also comprises a known powered lead-in roller 26 housed inside a cylindrical cavity 27 formed to one side of wall 15, and rotating or oscillating about an axis 28, parallel to axis 25, to feed tobacco 3 between teeth 24 and towards opening 21 along a channel 29 engaged by teeth 24 and defined on one side by wall 15 and on the other by the cylindrical periphery of roller 23. Finally, hurling unit 22 also comprises a hurling roller 30 powered to rotate, clockwise in Figure 2, about an axis 30a parallel to axis 25, and at a surface speed faster than that of roller 23. Roller 30 is located outside chamber 14, at opening 21 and the output end of channel 29, and presents radial teeth 31 engaging the gaps between teeth 24 of roller 23 to engage the tobacco 3 fed by roller 23 along channel 29, and so form a jet 32 directed downwards in a direction 33 inclined substantially crosswise to direction 20, and towards the transportation branch 34 of a conveyor belt 35 traveling in a direction 36 substantially parallel to direction 20, and defining the output portion of input portion 10 of path 9. Belt 35 is looped about two pulleys 37 and 38, the second of which is located at junction 12 and at the top end of a substantially vertical basin 39 divided into a top chamber 40 and a bottom chamber 41 by a known rotary slide valve 42. Chamber 41 communicates with a suction conduit 43 for withdrawing the heavy waste particles 44 falling along chamber 40 onto valve 42; and chamber 40 communicates with the outlet of a blower 45 for generating an air current along chamber 40 in an upward direction 46 substantially crosswise to direction 20. Finally, output portion 11 of path 9 is defined by a substantially vertical upflow channel 47 extending upwards from junction 12 and substantially aligned with the output of chamber 40, and which provides for feeding the light tobacco particles 48 onto the underside of conveyor belts 4 with the aid of the air current generated by blower 45, and an air current aspirated through belts 4 and through lateral openings 49 formed in channel 47. As shown more clearly in Figure 2, bottom portion 19 of plate 17 forms the top wall of the outlet nozzle 50 of a blowing device 51 for emitting a jet of compressed air directed in direction 20 and interfering with tobacco jet 32. In actual use, carding unit 8 feeds a continuous stream 52 of tobacco 3 to the input of channel 13 and along channel 13 to input channel 16 of chamber 14, where stream 52 is deflected by roller 23 along channel 29 and into engagement with roller 30 by which it is accelerated in direction 33 towards branch 34 of conveyor belt 35 in the form of jet 32. In the space between roller 30 and branch 34, jet 32 is intercepted by the air jet generated by nozzle 50 in direction 20, and is deflected transversely towards pulley 38. In view of the difference in inertia in direction 33, however, heavy particles 44 and light particles 48 in stream 52, and hence in jet 32, are obviously not deflected transversely in the same way. In fact, heavy particles 44 are deflected to a lesser extent, and settle on branch 34 relatively close to the outlet of nozzle 50 to form, on branch 34, a first layer 53 as shown in Figure 2; whereas light particles 48 are deflected to a greater extent, and settle on branch 34 further away from the outlet of nozzle 50 to cover layer 53 with a layer 54 and form, with layer 53, a stratified stream 52a of tobacco, which is fed by conveyor belt 35 to junction 12. At junction 12, stream 52a encounters the air current generated by blower 45, and is divided into a stream 52b of light particles 48, substantially corresponding to layer 54 and which is blown along channel 47 to conveyor belts 4, and a stream of heavy particles 44 forming layer 53. Being located, in stream 52a, beneath light particles 48 and facing basin 39, heavy particles 44 drop down into basin 39 together with a negligible quantity of light particles 48, which are easily separated from the accompanying heavy particles 44 by the air current blowing along chamber 40 in direction 46.

Claims: A method of supplying a cigarette manufacturing machine (2), the method comprising the steps of feeding a stream (52) of shredded tobacco (3) to at least one conveyor belt (4) along a supply path (9) comprising an upflow output portion (11), and an input portion (10) communicating, at a junction (12), with the output portion (11) and with a basin (39) into which heavy particles (44) in the stream (52) of tobacco fall; and stratifying the stream (52) of tobacco, as it travels along the input portion (10), to form a stratified stream (52a) comprising layers (53) of heavy particles (44) and layers (54) of light particles (48) adjacent to each other; characterized in that said stratification is achieved by so feeding the stream (52) of tobacco that it presents a first given traveling direction (33) at a given point (29) along said input portion (10); forming, at said given point (29), a jet (32) of tobacco traveling in said first direction (33); deflecting the jet (32) of tobacco in a second direction (20) substantially crosswise to said first direction (33); and causing the jet (32) to rain down onto a surface (34) defining a portion of said input portion (10). A method as claimed in Claim 1, characterized in that said jet (32) of tobacco is deflected by means of an air jet. A method as claimed in Claim 1 or 2, characterized in that said jet (32) of tobacco is formed by feeding said stream (52) to a hurling unit (22) defined by two counter-rotating toothed rollers (23, 30). A unit for supplying a cigarette manufacturing machine (2), the unit (1) comprising guide means (13, 29, 34, 47) for guiding a stream (52) of shredded tobacco comprising heavy waste particles (44), the guide means (13, 29, 34, 47) defining a path (9) along which to supply the stream (52) to at least one conveyor belt (4), and the path (9) comprising an upflow output portion (11), an input portion (10), and a junction (12) connecting the input and output portions (10, 11); a basin (39) into which the heavy particles (44) fall, the basin (39) communicating with the path (9) at said junction (12); hurling means (22) located at a given point (29) along said input portion (10), and for forming a jet (32) of tobacco traveling in a first direction (33); and a surface (34) defining a portion of said input portion (10), and for receiving said jet (32); the unit being characterized by also comprising deflecting means (50, 51) located between said given point (29) and said surface (34), and for deflecting said jet (32) in a second direction (20) substantially crosswise to said first direction (33). A unit as claimed in Claim 4, characterized in that said second direction (20) is substantially parallel to said surface (34). A unit as claimed in Claim 4 or 5, characterized in that said deflecting means (50, 51) are pneumatic deflecting means. A unit as claimed in Claim 4, 5 or 6, characterized in that said hurling means (22) comprise a chamber (14) presenting a lateral input (16) for said stream (52) of tobacco; a first toothed roller (23) located over said surface (34) and housed in said chamber (14) so as to rotate about an axis (25), the first roller (23) defining, with a wall (15) of said chamber (14), an output channel (29) for said stream (52); and a second toothed roller (30) rotating about an axis (30a) and cooperating with the first roller (23) to withdraw the tobacco (3) from said channel (29) in said first direction (33). A unit as claimed in Claim 7, characterized in that said deflecting means (50, 51) comprise a nozzle (50) oriented in said second direction (20) and located between said first roller (23) and said surface (34); and blowing means (51) for supplying air to said nozzle (50). A unit as claimed in Claim 8, characterized in that said nozzle (50) defines a bottom wall of said chamber (14). A unit as claimed in one of the foregoing Claims from 4 to 9, characterized by comprising conveyor belt means (35) extending beneath said hurling means (22) and up to said junction (12); said conveyor belt means (35) comprising a transportation branch (34) defining said surface (34).

Inventors: DRAGHETTI FIORENZO, MENGOLI FAUSTO, DRAGHETTI, FIORENZO, MENGOLI, FAUSTO
Applicants: GD SPA, G.D SOCIETA' PER AZIONI
Application year: 1996
Main classification: A24C5
IPC codes: A24C5