Abstract:
Filter plugs or sticks are directed from a filter maker onto a pair of conveyor rollers counter-rotating substantially in contact one with another at a point of tangency and furnished with equispaced peripheral flutes by which the single sticks are taken up and transferred from an infeed position to a release position. The flutes occupying a limited sector of each roller are connected selectively to a source of suction by an internal valve mechanism composed of a slide positionable to set the width of the sector, and a selector sleeve slidable axially between operating positions in which suction is generated across the sector through flutes spaced apart respectively at a longer pitch, and at a shorter pitch equivalent to half of the longer pitch.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a unit for conveying tobacco products.  
         [0002]     The prior art embraces manufacturing systems for tobacco products that comprise a transfer conveyor unit interposed between a production machine such as a filter maker, for example, and a user machine that might be a filter tip attachment machine, or an assembler of composite filters, that is to say filters consisting in a combination of filter plugs having different filtration properties.  
         [0003]     A conveyor unit of the aforementioned type would serve in this instance to transfer filter sticks or plugs, and will feed the sticks or plugs to the user machine either directly or employing temporary storage containers.  
         [0004]     Thus, in the case of a twin-track type of filter maker, the two tracks will be connected by two conveyor units to respective filter tip attachment machines, or possibly to two infeed points of a single machine assembling composite filters.  
         [0005]     The object of the present invention is to provide a unit for conveying tobacco products that will be extremely compact, versatile, and effective in the same measure when connecting either a one-track or a twin-track maker to either a single user machine or a plurality of user machines.  
       SUMMARY OF THE INVENTION  
       [0006]     The stated object is realized according to the present invention in a unit for conveying tobacco products, comprising a pair of rotary conveyors contrarotating substantially in contact one with another at a point of mutual tangency and furnished with angularly equispaced peripheral flutes each serving to accommodate a single product, by which products are transferred from an infeed position to a release position, also conveyor means feeding a succession of products to at least one of the rotary conveyors at the infeed position, and a device by which the peripheral flutes occupying at least one sector of given width presented by at least one of the rotary conveyors can be connected selectively to negative pressure means.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:  
         [0008]      FIG. 1  shows a unit for conveying tobacco products according to the present invention, illustrated schematically in a front elevation view with certain parts omitted and others in section;  
         [0009]      FIGS. 2 and 3  are schematic front elevation views of the unit for conveying tobacco products as in  FIG. 1 , shown enlarged and in two different operating positions;  
         [0010]      FIGS. 4   a  and  4   b  show a detail of  FIG. 3  in a section on IV-IV;  
         [0011]      FIG. 5  shows a detail of the conveyor unit as in FIGS.  1  to  4 , viewed in perspective. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     Referring to  FIG. 1 , numeral  1  denotes a unit for conveying tobacco products, in its entirety, interposed between a production machine  2  turning out filter sticks or plugs, shown schematically as a block, and receiving means denoted  3  and  4 .  
         [0013]     The production machine  2  is a twin-track filter maker, that is, a type having a garniture tongue  5  with two channels  6  and  7  extending side by side, along which respective continuous filter rods  8  and  9  are formed, and a rotary cutter  10  by which the two rods are divided respectively into discrete lengths consisting in filter sticks  11  and  12 , for example.  
         [0014]     The conveyor unit  1  presents a structure disposed symmetrically on either side of a vertical plane  13  parallel with and equidistant from the channels  6  and  7 , and comprises rotary conveyor means placed to take up and feed the filter sticks  11  and  12 , embodied as a pair of rollers  14  and  15  rotatable anticlockwise and clockwise, respectively, about corresponding horizontal axes  16  and  17  parallel to the vertical plane  13 .  
         [0015]     Each of the two rollers  14  and  15  is furnished peripherally with aspirating flutes  18  equispaced one from the next at a predetermined pitch P, into which respective sticks  11  and  12  are directed singly and in succession from the runout end of the tongue  5 .  
         [0016]     The unit  1  comprises further rotary conveyors consisting in a second pair of rollers  19  and  20 , identical one with another, mounted on shafts  21  and  22  of which the axes  23  and  24  extend parallel to the axes  16  and  17  of the feed rollers  14  and  15 , and rotatable thus clockwise and anticlockwise, respectively, at the same tangential speed as the aforementioned rollers  14  and  15 .  
         [0017]     The two rollers  19  and  20 , furnished peripherally with flutes  25  equispaced one from the next at a pitch p equivalent to half the pitch P of the flutes  18  aforementioned, are located respectively between the feed rollers  14  and  15  on the one hand, with which a substantially tangential interface is established at infeed positions denoted  26  and  27 , and on the other, positions  28  and  29  at which the sticks  11  and  12  are released to the aforementioned receiving means  3  and  4 .  
         [0018]     The two second rollers  19  and  20  also rotate substantially tangential one to another at a point denoted  30  and are positioned angularly on the respective shafts  21  and  22  in such a way that the single flutes  25  of the one roller  19  will align in succession with the single flutes  25  of the other roller  20  at the point of tangency  30 .  
         [0019]     Referring also to  FIGS. 4   a  and  4   b,  each of the two rollers  19  and  20  comprises two rotary members carried in rotation by the relative shaft  21  and  22 , and more exactly an outer sleeve  31  affording the flutes  25 , and an inner sleeve  32  constituting distribution means. Each shaft  21  and  22  also carries two fixed cylindrical elements  33  and  34  concentric one with another.  
         [0020]     As discernible in FIGS.  1  to  3 , the innermost cylindrical element  33  communicates by way of a duct  35  with a source of negative pressure (not illustrated) and is furnished with a through radial slot  36  directed toward the relative infeed position  26  and  27 .  
         [0021]     The outer cylindrical element  34  is fashioned with a radial slot  37  placed to coincide with the slot  36  of the inner element, and functions as the inner wall of a chamber  38  that extends angularly from a point coinciding with the infeed position  26  or  27 , through an arc of between 180° and 270°, and is delimited externally by the inner cylindrical surface of the distribution sleeve  32 .  
         [0022]     Numeral  39  denotes valve means consisting in a vane or slide  40  riding against the internal cylindrical surface of the distribution sleeve  32  and positionable thus within the chamber  38 .  
         [0023]     Thus, the chamber  38  is divided into a first portion or sector  41 , compassed between the infeed position  26  or  27  and the slide  40  and connected directly to the aforementioned negative pressure source by way of the slots  36  and  37 , and a second portion or sector  42  located downstream of the slide  40 , relative to the direction of rotation of the roller  19  or  20 , which remains at atmospheric pressure as will become clear in due course.  
         [0024]     Referring again to  FIGS. 4   a  and  4   b,  each of the peripheral flutes  25  is furnished with two holes  43  located at points near to its two ends, set apart one from another at a distance denoted d, whilst the inner or distribution sleeve  32  ( FIG. 5 ) presents a first set of holes  44  ordered in pairs axially aligned and set apart at the aforementioned distance d, and a second set of holes  45  ordered in pairs set apart likewise one from another by the same distance d, and offset axially by a given distance from the holes  44  of the first set.  
         [0025]     The paired holes  44  of the first set are arranged on the inner sleeve  32  equispaced angularly at a selected pitch P, whilst the paired holes  45  of the second set are equispaced at a pitch p equivalent to half the aforementioned pitch P.  
         [0026]     The inner sleeve  32  is mounted to the relative shaft  21  or  22  with freedom of axial sliding movement, induced by actuator means of conventional type (not illustrated), and positionable thus in such a manner as to bring about a first coupling between the two holes  43  in every second flute  25  of the outer sleeve  31  and each pair of holes  44  of the first set, spaced at pitch P (see  FIG. 4   a ), or alternatively, a second coupling between the two holes  43  in each and every flute  25  of the outer sleeve  31  and each pair of holes  45  of the second set, spaced at pitch p (see  FIG. 4   b ).  
         [0027]     Consequently, with the roller  19  or  20  set in rotation, in the case of the second coupling, all of the flutes  25  are connected to the negative pressure source when aligned on the first sector  41  of the chamber  38 , whereas in the case of the first coupling, the connection with negative pressure will occur by way only of every second flute  25 , when aligned on the selfsame first sector  41 .  
         [0028]     The valve means  39  combine with the distribution means  32  to create a device by which the flutes  25  are connected selectively to the source of negative pressure.  
         [0029]     In the operating configuration of  FIG. 1 , the slides  40  of the two rollers  19  and  20  are positioned at the respective release positions  28  and  29 , and the distribution sleeves  32  of the rollers  19  and  20  are positioned as in  FIG. 4   a,  in such a manner as to bring about the first coupling, that is to say with every second flute  25  connected to the source of negative pressure.  
         [0030]     In addition, the inner sleeves  32  of the two rollers  19  and  20  are positioned angularly relative one to another on the respective shafts  21  and  22  in such a way that when passing through the point of tangency  30 , under normal operating conditions, each aspirating flute  25  of the one roller  19  or  20  will align with a non-aspirating flute  25  of the other roller  20  or  19 .  
         [0031]     In this situation, the filter sticks  11  and  12  taken up onto the rollers  19  and  20  at the infeed positions  26  and  27  are transferred beyond the point of tangency  30 , with no mutual interference occurring between the two flutes  25  meeting at the selfsame point, and toward the release positions  28  and  29 , where the positioning of the slides  40 , each delimiting the aspirating first sector  41  of the relative chamber  38 , is such as to shut off the connection between the flutes  25  and the source of negative pressure.  
         [0032]     At this juncture, the filter sticks  11  and  12  are transferred respectively to the receiving means  3  and  4 , each of which comprises an inclined chute  46  emptying onto a relative horizontal conveyor  47  along which the filter sticks will accumulate en masse.  
         [0033]     Each conveyor  47  is looped at the ends around respective timing pulleys  48  of which one only, turning on a relative shaft  49 , is indicated in  FIG. 1 .  
         [0034]     More exactly, each chute  46  is furnished at the infeed end with a pivotable guide  50  hinged by a free top end to an inclined wall  51  forming part of the chute  46  and hinged in its turn about an axis parallel to the axis of the pulley shaft  49 .  
         [0035]     In the event of a blockage forming at the release positions  28  and  29  during normal operation, the guide  50  rocks on its pivot, tripping sensors of conventional type (not illustrated) that will cause the unit  1  to shut down.  
         [0036]     The operating configuration shown in  FIG. 2  differs from that of  FIG. 1  in that the inner sleeve  32  of one roller  19  is in the aforementioned second coupling position, whereby the two holes  43  of every flute  25  are matched with each pair of holes  45  of the second set, at the shorter pitch p (see  FIG. 4   b ), and the slide  40  is located at the release position  28 .  
         [0037]     In the case of the other roller  20 , the inner sleeve  32  occupies the first coupling position in which the two holes  43  of every second flute  25  are matched with each pair of holes  44  of the first set, at the longer pitch P (see  FIG. 4   a ), and the slide  40  is located at the point of tangency  30 .  
         [0038]     In this situation, the aspirating first sector  41  of the chamber  38  inside this roller  20  extends from the relative infeed position  27  to the point of tangency  30 , where the respective sticks  12  are taken up by the vacant flutes  25  of the other roller  19 , alternated with the flutes  25  occupied by the sticks denoted  11 . Once beyond the point of tangency  30 , accordingly, the sticks  11  and  12  of both streams will follow the same path toward the release position  28  associated with the receiving means denoted  3 .  
         [0039]     In the configuration of  FIG. 3 , the operating mode of the two rollers  19  and  20  described with reference to the example of  FIG. 2  is inverted, with the sticks  11  and  12  of both streams following the same path, beyond the point of tangency  30 , toward the release position  29  associated with the receiving means denoted  4 .  
         [0040]     The conveyor unit  1  thus described will be seen to be extremely versatile, given that different operating conditions can be accommodated simply by altering the angular position of the slide  40  within the chamber  38 , and the axial position of the inner sleeve  32 .  
         [0041]     With this in mind, the production machine  2 , which in the embodiment described by way of example is a twin-track filter maker, might equally well be replaced by two one-track machines turning out sticks  11  and  12  having identical or dissimilar properties, or even a single machine from which sticks  11  or  12  are taken up by just one roller  14  or  15 .  
         [0042]     Likewise in this instance, the sticks  11  or  12  can be directed by the second pair of rollers  19  and  20  toward both of the receiving means  3  or  4 , or to just one of these same receiving means.