Patent Publication Number: US-7584758-B2

Title: Device for processing tobacco during the production of cigarettes

Description:
DESCRIPTION 
   The invention relates to a device for the dressing of fibrous material for further processing, in particular to a distributor—which is known as a hopper—for the dressing of cut tobacco in the production of cigarettes, the tobacco being introduced into a closed container of the distributor and being treated in this by loosening up, the elimination of (tobacco) lumps and sifting, to form a tobacco strand, with the aid of a metering system. 
   Distributors or hoppers are an integral part of a cigarette production machine (maker). The cut and otherwise treated tobacco is introduced into the distributor in the region of an (upper) lock, and passes via a predistributor into the region of the metering system. The latter consists essentially of a specially designed metering roller, to which the tobacco is supplied in a uniform tobacco flow. In the prior art, downstream of this metering system thus or similarly designed, a sifting of the tobacco is carried out in order to eliminate constituents having a higher dead weight, in particular ribs, stalks and foreign objects. The tobacco is subsequently supplied to a strand conveyor which transports away an exactly dimensioned tobacco strand in order to form cigarettes. 
   The invention is based on the recognition that an optimum or complete sifting of the tobacco to eliminate constituents with a higher dead weight is important for the type of operation of the distributor/hopper and for the quality of the tobacco strand produced. The object on which the invention is based is, therefore, to develop further and improve a distributor, above all, with regard to the sifting of the tobacco. 
   To achieve this object, the device according to the invention is characterized in that the tobacco can be conducted through one or more sifters, the sifter or sifters preceding the metering system in the conveying direction of the tobacco. 
   According to the invention, therefore, the tobacco is sifted predominantly or exclusively in a region upstream of the metering system, so that tobacco freed of stalks, ribs and foreign objects is supplied to the metering system. 
   A particular feature of the invention is that at least one sifter precedes the distributor, overall, in such a way that the oncoming tobacco is first conducted through the sifter and, thereafter, tobacco freed of constituents having a higher dead weight is conducted into the distributor or into a lock of the latter. 
   The sifter may be designed in various ways. A particular feature is the use of a cone-type sifter, above all with regard to the positioning of the sifter outside the distributor or in front of the lock of the latter. This proposal is based on the recognition that cone-type sifters can also be employed, with surprising advantages, for the sifting of fibrous materials, such as cut tobacco. The sifted tobacco is in this case conducted directly into the distributor or into the lock of the latter by the blast or compressed air supplied to the sifter. 
   Alternatively or additionally, a sifter may also be positioned within the distributor, specifically preferably in the version with a zigzag-shaped sifting zone (zigzag sifter). It is advantageous to position at least one sifter downstream of a predistributor which consists of a plurality of rotating members for loosening of the tobacco. 
   A further particular feature is the configuration of a conveying zone for the tobacco downstream of the sifter, to be precise for supply to the metering system. 

   
     Further features of the invention are explained in more detail below by means of exemplary embodiments. In the drawing: 
       FIG. 1  shows a distributor in a side view, 
       FIG. 2  shows a detail of the distributor according to  FIG. 1 , to be precise a sifter, in the vertical section II-II of  FIG. 1 , 
       FIG. 3  shows the distributor according to  FIG. 1  in a vertical section in the sectional plane III-III of  FIG. 1 , on an enlarged scale, 
       FIG. 4  shows another embodiment of a distributor in vertical section, 
       FIG. 5  shows a detail V of the distributor according to  FIG. 4  on an enlarged scale, 
       FIG. 6  shows a third embodiment of a distributor in vertical section, 
       FIG. 7  shows a detail VII of the distributor according to  FIG. 6  on an enlarged scale. 
   

   The distributors or hoppers illustrated in the drawings serve for the dressing of cut tobacco. The latter is introduced, in an upper region, into the distributor, to be precise into a lock  10 . The tobacco is transferred from this to a predistributor  11 . A loosening-up of the tobacco takes place in the region of the latter. The tobacco is thereafter supplied to a metering system  12  in various ways. In the region of the latter, a largely regular tobacco stream  13  is produced, which is supplied in the upward direction to a member for producing a continuous tobacco strand, to be precise to a suction band  14 . 
   An important component of the distributor is a sifter  15 . This member separates constituents of the tobacco having a higher dead weight, in particular ribs, stalks, but also foreign objects, such as metal parts, stones, etc., from the tobacco. Where the present distributors are concerned, a sifter  15  is arranged in each case upstream of the metering system  12  in the conveying direction of the tobacco, so that sifted tobacco is supplied to the metering system  12 . 
   A particular feature is the distributor according to  FIG. 1 to 3 . Where this is concerned, the sifter precedes the distributor or the lock  10 . In point of fact, the sifter  15  is positioned as a separate member next to the distributor, specifically in a sifter housing  16 . The latter is connected to the distributor, to be precise to a distributor housing  17 . The unit thus obtained is arranged on a common machine stand  18 . 
   The otherwise pretreated cut tobacco is supplied to the sifter  15 . For this purpose, a supply line  19  or a supply pipe enters the sifter  15  from above in the vertical direction. The tobacco processed within the sifter  15  is introduced into the distributor, specifically into the lock  10  of the latter, in the upper region of the sifter  15  or of the sifter housing  16  via a connecting line  20 , to be precise a horizontally directed pipe. 
   The sifter  15  according to the exemplary embodiment of  FIG. 1  to  FIG. 3  is designed in a special way, to be precise as a (modified) cone-type sifter. This consists of an upright guide body  21  preferably positioned centrally within the sifter housing  16  and of a guide wall  22  arranged at a distance from the said guide body. Between the guide body  21  and guide wall  22  is formed an upright sifting duct  23 , the shape of which is determined by the contours of the guide body  21 , on the one hand, and by those of the outer guide wall  22 , on the other hand. In the present particular exemplary embodiment, the guide body  21  has a conical design, and, to be precise, consists of two double cones which lie one above the other and which are connected to one another in the region of a cross-sectional narrowing  24  to form a unit or a common guide body  21 . This tapers to a point at the top and is provided at the bottom with a truncated end  25 . 
   The guide body  21  is positioned centrally within the sifter housing  16  and is surrounded by the guide wall  22  in such a way as to form, as seen in horizontal section, an annular sifting duct  23 , the effective transverse dimension of which is approximately identical over the height, specifically owing to the adaptation of the guide wall  22  to the contours of the guide body  21 . The guide wall  22  runs parallel to and at a constant distance from the guide body  21 . 
   The tobacco is introduced into the sifter  15  via the supply line  19  arranged centrically with respect to the guide body  21  and above the latter. The tobacco moves, by virtue of its dead weight, downwards in the region of the sifting duct  23 , specifically along the outer surface area of the guide body  21 . The downwardly directed movement of the tobacco is counteracted by an airflow supplied from below. Air under increased pressure is introduced via an air line  26  into the lower region of the sifter  15  or of the sifter housing  16 . The air line  26  issues in a lower chamber  27  and enters the sifter housing  16  in the upward direction. The lower region of the guide wall  22  is designed to be air-permeable, to be precise as an obliquely directed or conical sieve  28 . The air enters the sifting duct  23  in an upwardly directed flow via this sieve-like lower region of the guide wall  22  and counteracts the downward movement of the tobacco. The light cut tobacco is thereby forced back in the upward direction, whilst pieces  29  having a higher dead weight (stalks, ribs, foreign objects) which are to be separated out fall downwards counter to the air stream. Located in the lower end of the sifting duct  23  is a discharge member for the pieces  29 , to be precise a cellular wheel  30  with discharge  32 . 
   The tobacco freed of the pieces  29  to be separated out passes into a region above the guide body  21 , to be precise into a collecting chamber  31  of widened cross section. This is followed, above it, by the connecting line  20  for transferring the sifted tobacco to the actual distributor. In this exemplary embodiment, the distributor is configured in a special way as a result of the absence of a sifter within the distributor or within the distributor housing  17 . A vacuum prevails in the lock  10  formed in the upper region, so that, in conjunction with the airflow in the sifter  15 , the tobacco passes out of the collecting chamber  31  via the connecting line  20  to the lock  10 . The tobacco is supplied in portions or batchwise to the sifter  15  and consequently to the distributor. The tobacco portion treated in the sifter  15  is collected in the lock  10  and is then supplied to the actual distributor. The lock  10  has a lower closable orifice. In the present exemplary embodiment, a lock bottom consists of two pivotable flaps  33 . These are pivoted downwards in order to open the lock  10 . The entire content of the lock  10  thereby passes into the region of the predistributor  11 . 
   In the predistributor, the tobacco is supplied by means of an obliquely directed guidance wall  34  to working members. These are (three) spiked rollers  35 ,  36 ,  37  which, by virtue of arrangement and size, control the free throughflow of the tobacco downwards into the region of a funnel-shaped collecting container  38 . The spiked rollers  35  . . .  37  are provided with radially directed spikes which, by virtue of their configuration and arrangement, have the effect of loosening up the tobacco, but also of guiding the tobacco stream. What is achieved is that the tobacco passes in a loosened up tobacco flow into the downwardly tapering collecting container  38  below the predistributor  11 . The spiked rollers  35  . . .  37  are in this case arranged in such a way that a spiked roller  37  of larger diameter and a smaller spiked roller  36  are located opposite one another and, as a result of the mutual engagement of spikes, form a barrier for the tobacco. The latter can pass downwards solely in accordance with the rotational movements of the spiked rollers  36 ,  37 . A further spiked roller  35  is located in a region above the spiked roller  36  and serves for feed-conveyance of the tobacco in such a way that the latter is conducted predominantly to the larger spiked roller  37 . The particularly advantageous direction of rotation of the spiked rollers  35 ,  36 ,  37  is identified in each case by a direction arrow in  FIG. 3 . 
   In the upper region of the funnel-shaped collecting container, in any event below the predistributor  11 , is arranged a feed conveyor—conveying worm  39 —which guides excess tobacco out of the region of the tobacco strand into the collecting container  38 . The guidance wall  34  is configured in such a way that it follows the contour of the spiked roller  37  of the predistributor  11  and ends in the upper region of the collecting container  38  so as to form a cross-sectional narrowing  40 . 
   The tobacco is conveyed upwards out of the collecting container  38 , specifically by means of a steep-angle conveyor  41 . This is an endless conveyor which has obliquely directed dogs  42  for in each case picking up a tobacco quantity in the region of an upwardly moved conveying side  43 . The latter is inclined slightly with respect to a vertical position, specifically with an inclination of about 6°. 
   The conveyor, to be precise the steep-angle conveyor  41 , is deflected via deflecting rollers into a downwardly directed conveying zone. In this region, the tobacco is transferred to the metering system  12 . The tobacco in this case passes into an essentially upright well  44  which supplies the tobacco to a metering roller  45 , to be precise a spiked roller. In the upper entry region of the well  44  is located a member for removing the tobacco from the steep-angle conveyor  41 . This is a separating roller  46  which combs the tobacco out of the comb-like dogs  42 . 
   The uniform tobacco stream  13  is produced in the region of the metering system  12  or of the metering roller  45  and is led via an upright conveyor, to be precise a suction well  47 , to the suction band  14 . At the lower end of the suction well  47  is arranged a discharge-conveyor member, to be precise a transversely directed conveying worm  48 . The latter has the task, in the event of a machine standstill, of conveying away tobacco which is located in this region. 
   In the exemplary embodiment according to  FIG. 4  and  FIG. 5 , the sifter  15  is accommodated within the distributor or within the correspondingly designed distributor housing  17 , specifically downstream of the predistributor  11 . The oncoming tobacco passes directly into the lock  10  via a supply line  49 . The predistributor  11 , in the version described, is located below the lock  10 . The tobacco emerging from this predistributor  11  is received by a cross conveyor  50 , to be precise an endless conveyor belt. The cross conveyor  50  or its upper side ascends slightly in the conveying direction, that is to say is directed at an acute angle. The cross conveyor  50  leads to an inlet orifice  51  into the sifter  15 . 
   The cross conveyor  50  has cooperating with it a metering member, specifically a metering conveyor  52  which is positioned as an endless belt above the cross conveyor  50  at an angle to the cross conveyor  50 . A deflecting end or deflecting roller  53 , facing the inlet orifice  51 , of the metering conveyor  52  forms, with respect to the cross conveyor  50 , a metering gap for the passage of the tobacco to the sifter  15 . The metering gap is adjustable, specifically as a result of the adjustment of the metering conveyor  52 . The deflecting roller  54  of the latter, the said deflecting roller being remote from the inlet orifice  51 , is mounted at a fixed location, whilst the opposite deflecting roller  53  is adjustable in the upward and downward direction. The metering conveyor  52  is therefore pivotable about the deflecting roller  54  so as to vary the metering gap defined by the cross conveyor  50 . 
   A spike roller  55  is arranged as a conveying and distribution member in the region of the inlet orifice  51  to the sifter  15 . 
   The sifter  15  is a zigzag sifter. An upright sifting duct  56  is multiply angled, that is to say has a zigzag-shaped design. Two parallel guidance walls  57 ,  58  define a sifting duct  56  having an alternating direction of flow. The tobacco passes via the inlet orifice  51 , in the region of an obliquely directed leg of the guidance wall  58 , into the sifter  15  or sifting duct  56 . The tobacco sliding downwards under its dead weight is counteracted from below by an air stream which, while separating out pieces  29  having a higher dead weight, conveys the tobacco back upwards, specifically beyond the inlet orifice  51  into the region of a (circular) deflecting duct  59 . This gives rise, in this region, to a tobacco stream  60  free of pieces  29 . This tobacco stream  60  is supplied to the metering system  12 . 
   The air introduced into the sifting duct  56  from below is generated by a blower or a fan  61  (cross-flow fan). The latter is located in an upright air duct  62  which forms with the sifting duct  56  a closed duct system. The blast air is introduced by the fan  61 , via an arcuately deflected duct leg  63 , from below into the sifting duct  56  and there generates the sifting action already described, in conjunction with an upwardly directed conveyance of the tobacco. 
   The upper region of the sifter  15  is designed in a special way ( FIG. 4  and  FIG. 5 ). An upper region of the air duct  62  leads to an air connection or to an air-permeable drum  64  designed, in particular, as a sieve. The latter is positioned rotatably and concentrically in the circular deflecting duct  58 . The drum  64  is driven in rotation in the conveying direction of the tobacco or of the tobacco stream  60 . The air is sucked into the air-permeable drum  64  via the sifting duct  56  by means of the fan  61  and is then introduced into the sifting duct  56  at the bottom via the air duct  62  and the duct leg  63 . 
   The relatively light tobacco, after leaving the sifting duct  56 , is lead along a circular wall of the deflecting duct  59  by means of the codirectional air flow. In this case, owing to centrifugal forces, the tobacco stream  60  bears against the wall of the deflecting duct  59 . In a downwardly directed region of the latter, the drum  64 , air-permeable overall, is sealed off relative to the passage of air by means of a stationary inner segment  65 , so that, in this region of low centrifugal forces, the tobacco stream  60  is prevented from bearing against the drum  64 . 
   The tobacco or tobacco stream  50  passes, downstream of the deflecting duct  59 , into the region of a cellular-wheel sluice  66  as a conveying and sealing-off member with respect to the vacuum region of the sifter  15 . The tobacco is transferred by the cellular-wheel sluice  66  to an oblique duct  67  which leads to the separating roller  46  arranged at the entrance of the well  44 . The tobacco consequently passes into the region of the metering system  12  which is designed here in the same way as in the exemplary embodiment of  FIG. 3 . 
   In the exemplary embodiment according to  FIG. 6  and  FIG. 7 , the sifter  15  is likewise accommodated within the distributor or within the distributor housing  17 . As in the example of  FIG. 4 , the tobacco is supplied directly to the lock  10  and is transferred from this to the predistributor  11 . The tobacco passes from here into the region of the collecting container  38  arranged below the predistributor  11 . The tobacco is transported to the said collecting container by an upward conveyor  68 , comparable in construction and functioning to the steep-angle conveyor  41  of  FIG. 3 , virtually over the entire height of the distributor. Downstream of an upper deflection of the upward conveyor  68  or of a conveying side  69 , the tobacco is transferred into a downwardly directed upright or vertical transport well  70 . The reliable removal of the tobacco from the upward conveyor  68  is brought about by a separating roller  71  which combs the tobacco out of the dogs  42  of the upward conveyor  68 . 
   The transport well  70  leads in the vertical direction directly to the sifter  15  or the sifter  15  follows the transport well  70 . In this exemplary embodiment, too, the sifter  15  is designed as a zigzag sifter with a corresponding sifting duct  56  which is delimited by angled parallel guidance walls  57 ,  58 . Here, too, at the upper inlet end of the sifting duct  56 , a processing roller  72  is arranged, which, on the one hand, causes the tobacco to be loosened up and, on the other hand, delimits the region of the sifter having an increased air pressure with respect to the preceding region—the transport well. 
   The sifting duct  56  is supplied from below with air which flows upwards and which conveys the tobacco upwards within the sifting duct  56 , but allows the pieces  29  to fall downwards on account of the higher dead weight. Transporting away by means of a transversely directed worm  73  takes place there. The airflow is generated in the lower region, directly adjacent to the lower end of the sifting duct  56 , specifically by means of a fan  74 . The latter is arranged in a housing as part of an upright air duct  75 . Once again, at the upper end of this air duct  75 , an air-permeable drum  64  driven in rotation in the direction of the arrow is mounted. This gives rise, in this exemplary embodiment too, to a circulation of air. The air introduced into the sifter or sifting duct  56  at the bottom transports the tobacco into the region of the drum  64 . The tobacco comes to bear here against the outer casing of the air-permeable drum  64  and is transported by the latter for transfer to an intermediate duct  76 . This is followed, again, by the metering system  12 , already described in principle, with separating roller  46  and well  44 . 
   A particular feature is the upper region of the sifter  15  with a presifting of the tobacco. Air is introduced laterally in a region preceding the sifter  15  in the conveying direction, to be precise in the transport well  70 . For this purpose, an air nozzle  77  is arranged next to the transport well  70  and is directed in such a way that air is directed into the transport well  70  and consequently into the tobacco stream in the transverse direction (arrow in  FIG. 7 ). 
   Opposite the air nozzle  77 , a branch duct  78  is formed. The issue of the latter forms an outlet orifice of the transport well  70 . The air from the air nozzle  77  guides part of the tobacco by means of a cross flow out of the transport well  70  into the branch duct  78 . The latter leads into a collecting region and is united with the tobacco supplied from the sifter  15 , specifically on the casing of the drum  64 . 
   Above the drum  64  is mounted an air-permeable boundary, to be precise an obliquely directed separating sieve  79 . The latter prevents tobacco from passing through into the upper region of the sifter housing  16 . 
   The exemplary embodiments shown with sifters configured in a special way, allow an extremely effective separation of the undesirable constituents from the tobacco by means of a compact construction and with high efficiency. 
   LIST OF REFERENCE SYMBOLS 
   
       
         10  lock 
         11  predistributor 
         12  metering stream 
         13  tobacco stream 
         14  suction band 
         15  sifter 
         16  sifter housing 
         17  distributor housing 
         18  machine stand 
         19  supply line 
         20  connecting line 
         21  guide body 
         22  guide wall 
         23  sifting duct 
         24  cross-sectional narrowing 
         25  end 
         26  air line 
         27  chamber 
         28  sieve 
         29  piece 
         30  cellular wheel 
         31  collecting chamber 
         32  discharge 
         33  flap 
         34  guidance wall 
         35  spiked roller 
         36  spiked roller 
         37  spiked roller 
         38  collecting container 
         39  conveying worm 
         40  cross-sectional narrowing 
         41  steep-angle conveyor 
         42  dog 
         43  conveying side 
         44  well 
         45  metering roller 
         46  separating roller 
         47  suction well 
         48  conveying well 
         49  supply line 
         50  cross conveyor 
         51  inlet orifice 
         52  metering conveyor 
         53  deflecting roller 
         54  deflecting roller 
         55  spike roller 
         56  sifting duct 
         57  guidance wall 
         58  guidance wall 
         59  deflecting duct 
         60  tobacco stream 
         61  fan 
         62  air duct 
         63  duct leg 
         64  drum 
         65  inner segment 
         66  cellular-wheel sluice 
         67  oblique duct 
         68  upward conveyors 
         69  conveying side 
         70  transport well 
         71  separating roller 
         72  separating roller 
         73  worm 
         74  fan 
         75  air duct 
         76  intermediate duct 
         77  air nozzle 
         78  branch duct 
         79  separating sieve