Abstract:
The invention concerns an apparatus and a method for removing foreign matter from tobacco to be processed. With known apparatuses, a stream of material substantially consisting of tobacco is guided over and through several components connected one behind the other, namely, delivery device, apparatus for removing foreign matter, vibrating element, conveying element for accelerating the stream of material, and an optical testing element. This takes up a large amount of space. Furthermore, the manufacturing costs for such apparatuses and the corresponding methods are high. The object of providing a compact and more cost-efficient apparatus is achieved by the fact that the apparatus for removing the foreign matter is arranged directly above the conveying element which accelerates the stream of material. Several components can be saved as a result, so that the space requirements as well as the manufacturing costs fall. The same applies to the corresponding method.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the priority of German Patent Application No. 10 2004 008 642.7 filed Feb. 19, 2004, the subject matter of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention is concerned with an apparatus for removing foreign matter from tobacco to be processed, in the direction of transport T of the tobacco, including a delivery device for delivering a stream of material essentially consisting of tobacco, an apparatus for removing foreign matter from the stream of material, at least one conveying element which accelerates the stream of material, and an optical testing element for detecting further foreign matter with a device for separating the foreign matter from the tobacco. Furthermore the invention concerns a method for removing foreign matter from tobacco to be processed, including the steps of: delivering a stream of material essentially consisting of tobacco to an apparatus for removing foreign matter from tobacco to be processed, removing foreign matter from the stream of material by means of the corresponding apparatus, passing the stream of material onto a conveying element which accelerates the stream of material, detecting further foreign matter by means of an optical testing element, and separating the foreign matter from the tobacco.  
         [0003]     Such apparatuses and methods are used in the tobacco-processing industry in tobacco preparation, also called primary. To prepare the tobacco which is usually packed as bales or the like in sacks, crates or the like for subsequent cigarette manufacture, apparatuses with the features of the introductory part of claim  1  and methods with the steps of the introductory part of claim  15  are known. To prepare the stream of material, it is necessary ideally to produce a so-called uniform monolayer of the tobacco from the thick-layer and usually unevenly distributed tobacco, in order to simplify or allow at all the detection of foreign bodies in the stream of material and separation thereof from the stream of material. Such apparatuses have, apart from the delivery device and the apparatus for removing foreign matter from the stream of material, the so-called string remover, a vibrating element, e.g. a vibrating belt or a vibrating channel, which is intended to be used to even out the stream of material. Downstream from the vibrating element in the direction of transport is a two-stage conveying element for accelerating the stream of material. At the end of the conveying element is arranged the optical testing element which is designed to separate out the previously detected foreign matter and has suitable devices for this purpose.  
         [0004]     Such apparatuses and methods, however, have the drawback that they have a very large design due to the large number of components. Secondly, manufacture of the known apparatuses, in particular because of the large number of components as well as the methods, are very expensive.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore the object of the present invention to propose a cost-efficient and compact apparatus which ensures distribution of the stream of material into a monolayer at least equivalent to conventional apparatuses. Furthermore it is the object of the invention to propose a cost-efficient method which is easy to handle and with low space requirements allows distribution of the stream of material into a monolayer of the required quality.  
         [0006]     This object is achieved firstly by an apparatus of the kind mentioned hereinbefore by the fact that the apparatus for removing foreign matter is arranged directly above the conveying element which accelerates the stream of material. As a result, the number of components is reduced, because e.g. the conveying element which is usually located below the apparatus for removing the foreign matter and the vibrating element arranged downstream from the apparatus can be dispensed with, so that a particularly compact and inexpensive-to-make apparatus is provided. Due to the arrangement of the apparatus for removing the foreign matter according to the invention above the conveying element which accelerates the stream of material, direct delivery of the stream of material is ensured, so that the stream of material has fewer transitions to overcome, with the result that the tobacco is conveyed particularly carefully. Furthermore, with the claimed apparatus good pre-distribution of the stream of material is achieved at the same time.  
         [0007]     Advantageously, the apparatus for removing foreign matter is composed of several remover rollers arranged adjacent to each other and rotatable by means of a rotary drive, wherein the speed of rotation or conveying of the remover rollers differs from, namely is preferably lower than, the speed of conveying of the conveying element which accelerates the stream of material. Particularly effective evening out is achieved by this speed difference, so that the previously thick-layer and irregular stream of material can be converted to a uniform monolayer of tobacco.  
         [0008]     In a preferred embodiment of the invention are provided at least two conveying elements which accelerate the stream of material and which are arranged one behind the other and in cascade fashion, wherein in the region of the rear conveying element is arranged a detection element for foreign bodies, particularly made of metal. As a result, additional and optionally usable components are integrated without increasing the space requirements of the apparatus as a whole.  
         [0009]     Furthermore, an embodiment is particularly preferred in which a sifter and the optical testing element form a unit, such that the sifter is directly associated with the optical testing element, namely, arranged immediately downstream from it. This also leads to a compact arrangement of the apparatus.  
         [0010]     Secondly, the object is achieved by a method with the steps mentioned hereinbefore by the fact that the stream of material is passed on directly from the apparatus for removing foreign matter from the stream of material to the conveying element which accelerates the stream of material, wherein the stream of material is placed on the conveying element from above. This allows cost-efficient removal of foreign matter, because reliable evening out of the stream of material is achieved with low space requirements, which is a precondition for the detection and removal of foreign matter and/or foreign bodies.  
         [0011]     Preferably, the conveying element is driven at a higher speed of conveying than the remover rollers, preferably at a speed 2 to 3 times higher. As a result, an optimised monolayer evenly distributed in length and breadth is created.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Further preferred and advantageous characteristics and developments are apparent from the subsidiary claims and the description. A particularly preferred embodiment and the method are described in more detail with the aid of the attached drawings. The drawings show:  
         [0013]      FIG. 1 a  schematic side view of an apparatus for removing foreign matter from tobacco to be processed,  
         [0014]      FIG. 2 a  schematic plan view of the apparatus as in  FIG. 1  with a detection element, and  
         [0015]      FIGS. 3   a  to  d  schematic views of remover rollers as part of the apparatus for removing foreign matter from the stream of material. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     The apparatuses shown serve to remove foreign matter, e.g. threads of the packing material, metal parts and the like, from a usually continuously conveyed stream of material.  
         [0017]     The apparatus  10  according to  FIG. 1  includes a delivery device  11  which can be designed as a channel, conveyor belt, chute or the like. On the delivery device  11  is arranged the stream of material  12  to be treated, which is laid, poured or otherwise placed on the delivery device  11  and conveyed continuously or intermittently in the direction of transport T. The stream of material  12  in the region of the delivery device  11  is as a rule distributed in a thick layer and irregularly in the direction of transport T and transversely thereto. Behind the delivery device  11  in the direction of transport T is arranged an apparatus  13  for removing foreign matter from the stream of material  12 , wherein the apparatus  13  is located slightly below the delivery device  11  in the vertical direction, so that the stream of material  12  has a gradient to overcome. Directly and immediately below the apparatus  13  is arranged a first conveying element  14  which serves to accelerate the stream of material  12  falling from above. Between the apparatus  13  and the conveying element  14  a gap is provided in the vertical direction. A further conveying element  15  is assigned to the conveying element  14 , wherein the conveying elements  14 ,  15  are arranged one behind the other and in cascade fashion. This means that the conveying element  15  in the vertical direction is arranged slightly below and overlapping the conveying element  14 , so that the stream of material  12  has a gradient to overcome. Above the conveying element  15  is arranged a further conveying element  16  which extends almost over the whole length of the conveying element  15  in the direction of transport T and runs approximately parallel or in a wedge shape to the latter in the direction of transport T. The stream of material  12  is processed within the apparatus  10  into a monolayer  17  which, lying on the conveying element  15 , can be transported into the region of an optical testing element  18 . The optical testing element  18  has a device for separating the previously detected foreign matter from the tobacco or from the monolayer  17 . For this purpose the optical testing element  18  is connected by its above-mentioned device to a control and/or regulating unit (not shown).  
         [0018]     The apparatus  13  for removing the foreign matter from the stream of material  12  has several remover rollers  19  arranged adjacent to each other or one behind the other in the direction of transport T. The remover rollers  19  are rotatable by means of rotary drives (not shown) about their respective axis of rotation  20 , wherein the axes of rotation  20  of the remover rollers  19  run parallel to each other and transversely to the direction of transport T. All the remover rollers  19  are provided with a gap from the respectively adjacent remover roller  19 . The gaps between the individual remover rollers  19  can be the same. However, a variable gap is preferred, this being in particular such that the gaps between the remover rollers  19  increase in the direction of transport T.  
         [0019]     The speeds of rotation or conveying of all the remover rollers  19  of an apparatus  13  are the same and synchronised. By suitable control and drive means, however, a separate speed of conveying can be produced for each remover roller  19  or groups of remover rollers. The speed of conveying of the remover rollers  19  on the one hand and of the conveying elements  14 ,  15  on the other hand differ from each other. Preferably, the speed of conveying of the remover rollers  19  is lower than the speeds of conveying of the conveying elements  14  and  15 . The speed of conveying of the conveying element  14  is approximately  2  to  3  times higher than the speed of conveying of the remover rollers  19 . Compared with the conveying element  14 , the conveying element  15  has a higher speed which is preferably about twice as high. Other speed ratios can, however, be produced in particular dependent on the desired result in formation of the monolayer  17 . The conveying element  16  in the shown embodiment has approximately the same speed of conveying as the conveying element  15  during operation. The conveying element  16  provided in particular for generating an air stream can, however, also have a speed of conveying different to the speed of conveying of the conveying element  15 .  
         [0020]     In the region of the rear conveying element  15  can optionally also be arranged a detection element  21  (see in particular  FIG. 2 ). The detection element  21  serves to detect foreign bodies in particular made of metal (e.g. aluminium foil) within the monolayer  17 . The detection element  21  is of linear construction and extends across the full width of the conveying element  15 , so that the monolayer  17  can be detected synchronously across the full width.  
         [0021]     In a further embodiment an additional sifter  22 , which can also be designed as a separator (air separator), and the optical testing element  18  form a unit. The sifter  22  is directly and immediately assigned to or arranged behind the testing element  18 , and is ideally even an integral part of the testing element  18 . The sifter  22  is designed in the usual known manner optionally for sifting light parts or sifting heavy parts, so that a detailed description is dispensed with.  
         [0022]     In embodiments not shown explicitly, the gaps between the remover rollers  19  can also decrease in the direction of transport T. Also the shape and design of the remover rollers  19  can vary. In  FIGS. 3   a  to  c  only selected examples are shown. In  FIG. 3   a  a conventional cylindrical roller shape is shown. The convex roller shape shown in  FIG. 3   b  in which, starting from the edge, the diameter increases towards the centre and then decreases again to the opposite end, serves particularly for improved distribution or evening out of the stream of material  12  transversely to the direction of transport T. The same applies to the roller shape as in  FIG. 3   c . Also different roller shapes can be combined in one apparatus  13 . The remover rollers  19  also do not have to be oriented parallel to each other, but can be arranged at an angle to each other, e.g. in a zigzag shape in plan view.  FIG. 3   d  shows a further embodiment of the design of the remover rollers  19  which serves for uniform tobacco distribution. In this, each remover roller  19  is split, this being into two roller elements  19   a  and  19   b . The roller elements  19   a  and  19   b  or their axes of rotation  20   a  or  20   b  run obliquely to each other. In the region of a point of intersection of the axes of rotation  20   a  and  20   b  can optionally be provided a cover element  23  which closes the gap between the tilted roller elements  19   a  and  19   b.    
         [0023]     Below, the principle of the method is described in more detail with the aid of  FIGS. 1 and 2 . At one or more delivery points, raw tobacco is placed on the delivery device  11  as bulk material or otherwise over the full width or only in defined regions. By means of the delivery device  11  the tobacco is conveyed in the direction of transport T as a stream of material  12  in a thick layer which can have different heights. The stream of material  12  drops onto the remover rollers  19  at the junction with the apparatus  13 , i.e. the string remover, as described e.g. in the document of EP application number 03090079.9. By rotation of the remover rollers  19 , the stream of material  12  is conveyed in the direction of transport T and pre-distributed in the process. This means that the stream of material  12  is pulled apart, that is, thinned. Due to the variable gaps, or gaps increasing in the direction of transport between the remover rollers  19 , the tobacco then falls evenly onto the driven conveying element  14 . The stream of material  12  on the conveying element  14  is already much thinner and above all considerably more even compared to the delivery device—inter alia due to the higher speed of conveying of the conveying element  14  compared with that of the remover rollers  19 . Foreign matter in the stream of material  12 , e.g. threads from the jute sacks as packing material of the raw tobacco, is picked up by the remover rollers  19  and hence removed from the stream of material.  
         [0024]     The stream of material  12  lying on the conveying element  14  is accelerated, this being in two stages, as the stream of material  12  is transferred from the conveying element  14  with a first speed of conveying v 1  to the conveying element  15  with a second speed of conveying v 2 , where v 2 &gt;v 1 . In the region of the transition from the conveying element  14  to the conveying element  15 , the stream of material  12  drops down onto the conveying element  15 , as a result of which the stream of material  12  is pulled still further apart to form the monolayer  17 . This monolayer  17  is held on the conveying element  15  in the embodiment shown by an air stream which is generated by the drive of the conveying element  16 . By the conveying element  15 , the monolayer  17  is passed through the optical testing element  18  in which foreign matter and/or foreign bodies are detected and directly and selectively separated out in a known manner.  
         [0025]     Optionally, the monolayer  17  can also be detected before entering the optical testing element  18 , wherein in particular metal parts are detected and separated out of the monolayer  17 . The detected and/or optically tested monolayer  17  which is freed from foreign matter and/or foreign bodies is then delivered for further processing. The monolayer  17  can be delivered via a transport element to a sifter  22 . For this purpose the monolayer  17  or the tobacco falls in a parabolic curve onto the transport element. Preferred is, however, delivery of the monolayer directly to the sifter  22 , wherein the tobacco falls in a parabolic curve directly into the sifter  22 . Depending on the customer&#39;s requirement, sifting of heavy parts or sifting of light parts can take place in the sifter  22 .  
         [0026]     If using the remover rollers  19  in  FIGS. 3   b  and  c , the stream of material  12  is expanded in the region of the apparatus  13 , namely due to the special shape passed in particular to the outer edges of the remover rollers  19 , so that evening out occurs by pulling the stream of material apart transversely to the direction of transport T.  
         [0027]     The invention has been described in detail with respect to exemplary embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.