Abstract:
In a cigarette maker, shredded tobacco is directed by a conveyor into a riser and ascends as a flow of distinct particles toward an aspirating belt, placed at the top outlet end of the riser, by which the particles are attracted and gathered progressively to form a stream of tobacco filler. The riser is made up of a lower first portion in receipt of the tobacco from the conveyor, and an upper second portion enclosed by the aspirating belt; the first portion is embodied separately from the second portion, and the two portions are inter-connected by the revolving surface of a toothed suction roller designed to transfer a uniform layer of tobacco from the first portion to the second.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a cigarette maker.  
           [0002]    The prior art embraces cigarette making machines, with single or multiple processing lines, typically comprising an infeed chamber from which shredded tobacco is taken up by a carding unit and directed into a descent channel or chute.  
           [0003]    At the bottom end of the chute, the tobacco is transferred by a toothed outfeed unit onto a feed conveyor and then carried by this same conveyor toward the bottom inlet end of an ascending channel or riser. As the tobacco enters the inlet of the riser, stems and heavier particles, or scraps, are separated from the lighter particles, whereupon the stems and scraps drop by gravity into a collection vessel and will be rejected, whilst the lighter particles, used in the manufacturing process, are carried up the riser on an ascending air current.  
           [0004]    The top end of the riser is enclosed by a single conveyor, in the case of a machine with just the one processing line, or two conveyors side by side in the case of a machine with two lines. Reference will be made explicitly during the course of the following specification to a cigarette maker with two lines, albeit implying no limitation in scope.  
           [0005]    Each conveyor takes the form of a substantially horizontal air-permeable, aspirating belt capable of attracting the tobacco directed up through the riser as a continuous flow of divided particles, and causing it to form gradually into a continuous stream of filler. The flow of air ascending through the riser, which carries the tobacco up toward the aspirating belts, is generated by negative pressure created internally of an elongated vacuum chamber enclosed on the underside by the two belts. The streams of tobacco forming thus beyond the outlet of the riser are directed by the aspirating belts through a trimming station of which the function is to reduce the stream to a predetermined and uniform thickness, or depth. The trimmed streams of tobacco are then released by the aspirating belts to the entry point of a station where they are formed into two respective continuous cigarette rods.  
           [0006]    As production tempo increases, cigarette makers of the conventional type in question betray certain drawbacks with regard in particular to the correct formation of the tobacco stream on the aspirating belts. More exactly, a higher operating speed must be accompanied necessarily, one the one hand, by a higher linear velocity of the aspirating belts, and on the other by a faster ascending movement of the tobacco particles within the riser.  
           [0007]    For the tobacco particles to ascend more quickly through the riser as required, air must be drawn by the vacuum chamber through the aspirating belts at a higher rate of flow. A first consequence of such an increase is that the aspirating belts are soon saturated transversely, as the tobacco will tend to accumulate non-uniformly in the vertical direction, perpendicular to the belts, with the density of the particles at its greatest near the surface of the belts and decreasing substantially in hyperbolic mode as the distance from the belts increases. A second consequence is that of a more violent impact between the tobacco particles and the surfaces of the aspirating belts, which causes the particles to slip, roll and bounce against the belts and results ultimately in an uneven and incorrect distribution of the particles along the direction followed by the belts.  
           [0008]    Another drawback tending to accompany the higher operating speeds of conventional cigarette makers described above is reflected in an unsatisfactory separation of the stems and the heavier scraps of tobacco from the lighter particles. In practice, the faster the tobacco is directed into the riser, the shorter the duration of the separation process becomes, and with the area of the machine where the process in question takes place tending typically to be somewhat restricted, the stems and heavier scraps of tobacco are liable to be entrained in the upward current when air is drawn through the riser at high speed.  
           [0009]    The object of the present invention is to provide a cigarette maker unaffected by the aforementioned drawbacks.  
         SUMMARY OF THE INVENTION  
         [0010]    The stated object is realized according to the present invention in a cigarette maker comprising at least one ascent channel through which to direct a flow of tobacco particles, a feed system by which the tobacco is supplied to the ascent channel, and at least one aspirating belt set in motion adjacent to the outlet of the ascent channel, on which the flow of particles is formed into a corresponding stream of tobacco. The ascent channel is composed of a lower first portion designed to receive the tobacco, and an upper second portion enclosed by the belt, and can be equipped advantageously with conveyor means interposed between the first portion and the second portion, of which the function is to transfer a predetermined quantity of tobacco from the one portion to the other portion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:  
         [0012]    [0012]FIG. 1 illustrates a first embodiment of the cigarette maker according to the present invention, viewed schematically in a vertical section;  
         [0013]    [0013]FIG. 2 shows a first portion of the cigarette maker according to the present invention, viewed schematically in a vertical section and illustrated in a second embodiment;  
         [0014]    [0014]FIG. 3 is a variation on a detail of FIG. 2;  
         [0015]    [0015]FIG. 4 shows a second portion of the cigarette maker according to the present invention, viewed schematically in a vertical section and illustrated in the aforementioned second embodiment;  
         [0016]    [0016]FIG. 5 shows the portion of FIG. 4 in a plan view, illustrated schematically and with certain parts cut away.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    With reference to FIG. 1, which illustrates a first embodiment of the cigarette maker according to the invention, and in particular a machine with a single processing line,  1  denotes an infeed portion, in its entirety, of such a machine.  
         [0018]    The infeed portion  1  comprises a feed unit  2  by which a mass of shredded tobacco is formed into a continuous flow of tobacco particles. The various components making up the feed unit  2  are housed within a vertically extending enclosure  3  delimited uppermost by a horizontal wall  4  and on either side by two vertical walls  5  and  6 .  
         [0019]    The infeed portion  1  presents an inlet duct  7  extending upward from the horizontal wall  4 , and below the duct, internally of the enclosure  3 , a power driven toothed roller  8  by which the shredded tobacco  9  is directed down into a lower chamber  10  delimited at the bottom by a conveyor belt  11 .  
         [0020]    The chamber  10  accommodates a carding roller  12  rotatable about an axis  13  transverse to the side walls  5  and  6 , forming part of a carding unit  14  and positioned adjacent to the downstream end of the belt  11 .  
         [0021]    In addition to the carding roller  12 , the unit  14  comprises a proportioning roller  15  rotatable substantially tangential to the carding roller  12  and in the same direction.  
         [0022]    With this arrangement, the shredded tobacco  9  is directed by the toothed roller  8  onto the belt  11  and thence toward the carding roller  12 , whereupon a layer of the tobacco  9  substantially equal in thickness to the radial dimension of the carding teeth is transferred by the roller  12  away from the chamber  10  and beyond its position of tangential proximity to the proportioning roller  15 .  
         [0023]    The infeed portion further comprises an impeller roller  16  rotatable about an axis parallel to the axis  13  aforementioned, of which the function is to pick up the layer of tobacco  9  from the carding roller  12  and project the constituent particles, in the direction denoted F 1 , down into a substantially vertical descent channel or chute  17  delimited by two side walls  18  and  19  extending parallel one with another and with the axis  13  of the carding roller  12 .  
         [0024]    The bottom end of the chute  17  is positioned facing the periphery of a toothed take-up unit  20  that comprises a take-up roller  21  and an impeller roller  22  combining one with another to transfer the shredded tobacco  9  away from the chute  17 .  
         [0025]    More exactly, the tobacco  9  is received by the take-up unit  20  in the form of distinct particles and projected onto conveyor means  23  of which the function is to direct the shredded material toward an ascent channel or riser  24  enclosed at the top end by the moving surface of an aspirating belt  25  fashioned from air-permeable material.  
         [0026]    In accordance with the present invention, the riser  24  is divided into a lower first portion  26  and an upper second portion  27 , of which the top end  28  is enclosed by the aforementioned aspirating belt  25 . The two portions  26  and  27  are separated and interconnected by conveyor means denoted  29  in their entirety, interposed between the outlet  30  of the first portion  26  and the inlet  31  of the second portion  27 .  
         [0027]    The length of the first portion  26 , as measured along the direction of movement of the belt  25 , is identical to the corresponding length of the second portion  27 , whereas it will be seen from FIG. 1 that the width of the first portion  26 , measured transversely to this same direction, is appreciably greater than that of the second portion  27 .  
         [0028]    The aforementioned conveyor means  29  could be of any given type, and will be capable of transferring a predetermined quantity of tobacco  9  between the outlet  30  of the first portion  26  and the inlet  31  of the second portion  27  of the riser  24 .  
         [0029]    In particular, the conveyor means  29  will consist in any suitable conveying device capable of motion along a path that describes an endless loop. In the example illustrated, such means take the form of a toothed roller  32  rotatable clockwise, as viewed in FIG. 1, about an axis  33  parallel to the axis  13  of the carding roller  12 , also to the direction of movement of the aspirating belt  25 , and connected to a source  34  of negatively pressurized fluid in such a way that suction can be generated through the outer surface of the roller  32 . Instead of a roller  32 , alternatively, use could be made of a belt looped around a plurality of pulleys with axes parallel to the axis  13  of the carding roller  12  and to the direction of movement of the belt  25 .  
         [0030]    In the case of the roller  32 , the looped path appears as a circular circumference and includes a first sector  35 , on which a layer  36  of tobacco  9  is formed, and a second sector  37  from which the particles  38  making up the layer  36  of tobacco  9  are released.  
         [0031]    More exactly, the first sector  35  coincides with the part of the roller  32  extending upward from and along the outlet  30  of the first portion  26  of the riser  24 , whilst the second sector  37  coincides with the part of the roller  32  extending along the inlet  31  of the second portion  27  of the riser  24 .  
         [0032]    The path described by the toothed roller  32  also presents a third sector  39  interposed between the first and second sectors  35  and  37 , occupied by metering and leveling means  40  which take the form of an equalizing roller  41  offered tangentially to the toothed roller  32 . The roller  41  in question is rotatable counterclockwise, as viewed in FIG. 1, about an axis  42  extending parallel to the axis of the toothed roller  32 , and at a speed marginally different to that of the latter roller  32 . In this way, the equalizing roller  41  is able to ensure a uniform thickness of the aforementioned layer  36  of tobacco by redistributing particles from areas of greater density to areas of lesser density that may have formed in the layer.  
         [0033]    As discernible in FIG. 1, the aforementioned lower first portion  26  of the riser  24  terminates at the bottom end in a downwardly inclined wall  43  of which the higher part is directed toward the conveyor means  23  bringing the tobacco  9  from the toothed take-up unit  20 .  
         [0034]    The inclined wall  43  presents a plurality of holes  44  through which to direct a pressurized fluid from a relative source denoted  45 , of which the purpose will be described in due course.  
         [0035]    The conveyor means  23  take the form of a first vibrating tray  46  such as will slow the rate at which the tobacco advances toward the inlet of the first portion  26  of the riser  24 .  
         [0036]    Also associated with the toothed roller  32  at a point near the inlet of the upper second portion  27  of the riser  24 , coinciding substantially with the second or release sector  37  of the looped path, are means denoted  47  by which to shut off the suction generated by the source  34  of negative pressure, and/or means denoted  48  by which to generate a flow of positively pressurized fluid. Such means  48  might consist, by way of example, in a nozzle  49  connected to a source  50  of pressure and angled convergently with the direction of movement of the aspirating belt  25 . The aspirating action of the belt  25  combines with the dislodging flow blown by the nozzle  49 , which includes a component oriented along the feed direction of the belt  25 , to bring about an efficient transfer of the particles  38  of tobacco  9  from the surface of the roller  32  to the belt  25 .  
         [0037]    Thus, the particles  38  cling to the aspirating belt  25  and form progressively into a continuous stream (not illustrated), which on emerging from the second portion  27  of the riser  24  will advance on the belt  25  toward successive stations (not illustrated) where it is trimmed, shaped and formed ultimately into a continuous cigarette rod.  
         [0038]    It will be seen that, with the width of the first portion  26  significantly greater than the width of the second portion  27 , which is substantially equal to that of the aspirating belt  25 , and the width of the sector  35  on which the layer  36  of tobacco  9  is formed likewise much greater than the width of the aspirating belt  25 , it becomes possible with only a relatively modest speed of rotation of the toothed roller  32  about its axis  33  and a relatively modest velocity of the particles  38  of tobacco  9  within the riser  24 , for the belt  25  to be supplied with the correct quantity of tobacco  9  even when running at relatively high speed, and in such a manner as to guarantee a substantially uniform stratification of the tobacco  9  on the aspirating surface, both along the direction of movement of the belt  25  and in the vertical dimension, normal to the belt  25 . Also, and to advantage, the process of separating the stems and larger scraps of tobacco  9  from the smaller particles occurs internally of a spacious enclosure afforded by the lower first portion  26 , with the tobacco particles substantially detached one from another and progressing at a comparatively gentle rate of motion. The succession of selection jets delivered through the holes  44  also helps to increase the efficiency of the process whereby the stems and heavier scraps of tobacco are separated out. The stems and heavier scraps  54  drop into a collection trough  55 .  
         [0039]    [0039]FIGS. 2, 3 and  4  illustrate a second embodiment of the infeed portion  1  forming part of a cigarette maker according to the invention, and in particular a machine with two processing lines, that is to say equipped with two aspirating belts  25  on which two identical streams of tobacco are formed.  
         [0040]    As regards the structure and operation of the risers  24  and the toothed rollers  32 , it will be seen that there is no difference between this and the single line embodiment of FIG. 1.  
         [0041]    In particular, as illustrated in FIGS. 4 and 5, the infeed portion  1  of the machine comprises two risers  24  conveying two respective flows of tobacco particles  38 , and two aspirating belts  25  located each above the top outlet end  28  of the relative second portion  27  of a corresponding riser  24 , on which the two flows of particles  38  are formed into respective streams of tobacco  9 .  
         [0042]    More exactly, the risers  24  and the respective toothed rollers  32  are disposed symmetrically on either side of a vertical plane  51  lying between the two aspirating belts  25 , as discernible in FIGS. 4 and 5, and positioned transversely to the axes of rotation of the carding roller  12  and of the take-up roller  21 , as illustrated in FIG. 5. In the solution of FIGS.  2  to  5 , more exactly, the toothed conveying rollers  32  are centered on respective axes  33  rotated through an angle of 90° (ninety degrees) relative to the viewing plane of the drawings, as compared to the position of the single roller  32  illustrated in FIG. 1, where the axis  33  of rotation extends parallel to the axis of the carding roller  12 .  
         [0043]    In the example of FIG. 5, the tobacco  9  is carried from the take-up roller  21  toward the two risers  24  by conveyor means  23  comprising a common first portion  52  and a pair of mutually independent second portions  53 . The two independent portions  53  extend divergently from the common portion  52  and on either side of the vertical plane of symmetry, in such a way that the particles  38  of tobacco  9  are carried toward respective inclined walls  43  presented by the two lower first portions  26  of the corresponding risers  24 .  
         [0044]    In like manner to the example of FIG. 1, each of the two inclined walls  43  in this embodiment will present a plurality of holes  44  from which to generate a succession of air jets designed to aid the efficient separation of any stems and heavier scraps  54  of tobacco from the lighter particles. Here again, the stems and scraps  54  drop into a collection trough  55 .  
         [0045]    In particular, both the common first portion  52  and the independent second portions  53  consist in respective vibrating trays  56  and  57 .  
         [0046]    In the example of FIG. 2, the particles  38  of tobacco  9  leaving the take-up roller  21  drop onto a conveyor  58  moving from right to left as viewed in FIG. 2, and angled upward in such a manner that the forwardmost edge will be positioned over the vibrating tray  56  constituting the common first portion  52 .  
         [0047]    Thus, the particles  38  of shredded tobacco  9  are advanced at a suitably measured rate of feed toward the two bottom walls  43  presented by the two first portions  26  of the risers  24 . Here, the stems and scraps  54  are separated and the lighter particles are directed upward through the first portions  26  in a continuous flow, entrained in a current of air generated by pneumatic means of familiar embodiment (not illustrated). On reaching the first sector  35  of each toothed roller  32  set in rotation about the relative axis  33 , the flow of tobacco particles  38  will thicken progressively and at low speed on the surface of the roller  32  passing momentarily over the outlet  30  of the first portion  26 , forming into a layer  36 . Each layer  36  of tobacco is distributed and spread by the relative equalizing roller  41  and advances gradually toward the second sector  37  of the roller  32 . At this point, the suction shut-off means  47  and/or the nozzles  49  are activated, so that the layer  36  of tobacco  9  is caused to detach from the surface of the roller  32  and gather into a new flow of particles  38 . Exposed to the combined action of the aspirating belts  25  and of the jets delivered by the relative nozzles  49 , the released particles will cling progressively to the belts  25  and form into a continuous stream of tobacco on each one.  
         [0048]    Finally, it will be seen in the illustration of FIG. 3 that the particles  38  of tobacco  9  are released by the rollers  21  and  22  directly onto the common vibrating tray  56 .