Abstract:
The friction coefficient of the product-conveying and/or treating surface of a drum-shaped or belt-shaped conveyor can be restored or maintained at a desired value by the application thereto of a film of polyvinyl acetate or a dispersion of acrylate, preferably on top of a layer of caoutchouc of the like. The conveyor can cooperate with a stationary or mobile rolling member to convolute adhesive-coated uniting bands around groups of coaxial plain cigarettes, cigars or cigarillos and filter mouthpieces, or it can serve as a means for transporting continuous strips or webs or series of discrete bands in tobacco processing and/or other plants.

Description:
CROSS REFERENCE TO RELATED CASES  
         [0001]    The present application claims the priority of the commonly owned copending German patent application No. 101 17 176.5 filed Apr. 6, 2001. The disclosure of the above-referenced German patent application, as well as that of each U.S. and foreign patent and patent application identified in the specification of the present application, are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to conveyors in general, and more particularly to improvements in apparatus which can be utilized with advantage for the transport and, if necessary, simultaneous treatment or processing of certain commodities (such as semifinished products) of the tobacco processing industry.  
           [0003]    Rod-shaped products of the tobacco processing industry often undergo a treatment which involves the establishment of contact with conveyors which cause the products to roll about their longitudinal axes and to simultaneously move sideways. For example, filter cigarettes can be made by contacting a pair of coaxial plain cigarettes of unit length and a filter mouthpiece of double unit length between the plain cigarettes with an adhesive-coated uniting band and by causing the three coaxial commodities to roll about their common axis in a direction to convert the uniting band into a tube which surrounds the filter mouthpiece and the adjacent end portions of the plain cigarettes and sealingly connects the cigarettes with the mouthpiece. The resulting filter cigarette of double unit length is severed midway across the tube to yield a pair of filter cigarettes of unit length. Reference may be had, for example, to commonly owned U.S. Pat. No. 5,135,008 granted Aug. 4, 1992 to Oesterling et al. for “METHOD OF AND APPARATUS FOR MAKING FILTER CIGARETTES”. This patent discloses a rolling unit which employs a drum-shaped conveyor ( 31 ) and a stationary rolling member ( 32 ).  
           [0004]    Rotary drum-shaped conveyors and stationary rolling members can be replaced with pairs of endless belt or band conveyors which define a rolling channel wherein successive rod-shaped articles move sideways because one of the belts moves while the other belt is stationary or because the two belts move at different speeds. Such belts are known as functional belts or bands and their operation is satisfactory, especially for extended periods of time, if their article- or product-contacting surfaces meet certain prerequisites such as roughness. The same holds true for the peripheral surfaces of drum- or roller- or pulley-shaped conveyors.  
           [0005]    Presently known proposals to treat the article-contacting surfaces of drums, rollers, belts or other article advancing and treating (such as rolling) conveyors include the application of a coat or film or layer of caoutchouc which enhances the nonskid properties of the conveyors. Such nonskid properties are further enhanced by subjecting the exposed surface of the film of caoutchouc or the like to a grinding treatment which raises the friction coefficient of the film or layer by imparting thereto a rugged (fissured or imbricated or scaled) pattern.  
           [0006]    A drawback of the just discussed prior proposals is that repeated frictional contact of the roughened exposed surface of the layer of caoutchouc or the like with paper (such as cigarette paper and/or so-called tipping paper which is utilized to make uniting bands in filter cigarette making machines) entails a reduction of roughness and thus adversely affects the reliability or predictability of the rolling, wrapping, advancing and/or other treatment of the rod-shaped articles and uniting bands. The condition of the exposed surface of a film or layer of caoutchouc on a rotary and/or otherwise advancing conveyor is also affected by deposits of minute particles of paper, chalk and/or others which gather on the exposed surface and affect the friction coefficient of the conveyor.  
           [0007]    Attempts to remove minute particles of paper or the like from the recesses in the exposed surface of a layer of caoutchouc or the like by washing have met with no success, i.e., the only presently known solution is to replace the conveyors with non-contaminated conveyors even though, save for the presence of contaminants, the condition of their exposed surfaces is still quite acceptable for their intended purpose. This results in unnecessary waste of valuable parts and contributes to the maintenance cost of filter cigarette making and other machines which must employ conveyors with surfaces that must be brought in repeated predictable frictional engagement with the transported products.  
         OBJECTS OF THE INVENTION  
         [0008]    An object of the present invention is to provide a novel and improved arrangement for the manipulation (such as conveying and/or rolling) of certain commodities, e.g., rod-shaped smokers&#39; products, whose useful life is much longer than that of presently known arrangements.  
           [0009]    Another object of our invention is to provide a novel and improved endless belt or band for use in filter cigarette making machines or the like.  
           [0010]    A further object of this invention is to provide rotary, flexible and/or other types of conveyors with films and/or layers which can stand longer periods of continuous or intermittent use than presently known layers.  
           [0011]    An additional object of the instant invention is to provide a machine for the manipulation of rod-shaped commodities with one or more conveyors whose useful life is a multiple of that of presently known conveyors.  
           [0012]    Still another object of this invention is to provide a novel and improved method of prolonging the useful lives of conveyors for rod-shaped smokers&#39; products such as filter cigarettes, cigars, cigarillos and many others.  
           [0013]    A further object of the invention is to provide a machine for the making of filter cigarettes, cigars, cigarillos and analogous rod-shaped smokers&#39; products which are superior to those made in presently known machines.  
           [0014]    Another object of our invention is to reduce the tendency of belt conveyors and/or other conveyors to gather and retain impurities which adversely affect their utility and/or other desirable properties.  
         SUMMARY OF THE INVENTION  
         [0015]    A feature of the present invention resides in the provision of an arrangement which can be utilized to manipulate smokers&#39; products, e.g., to transport and to simultaneously treat (such as roll) rod-shaped articles of the tobacco processing industry. The improved arrangement comprises at least one conveyor having a product-contacting surface which exhibits a relatively high friction coefficient, and a substance which is applied to the at least one conveyor and serves to at least retard a lowering of the friction coefficient.  
           [0016]    The substance can form a protective film which is applied to the product contacting surface and exhibits paper-repellent characteristics. The film is or can be sufficiently thin to ensure that the outline of the product-contacting surface remains at least substantially unchanged. The surface can be provided with crevices (this term is intended to embrace recesses, cracks, interstices and like configurations) provided in the exposed side of a layer of elastic material (such as caoutchouc) which defines the product-contacting surface and bears the aforementioned film.  
           [0017]    If the conveyor is to treat and/or to transport smokers&#39; products, the composition of its layer and its film should conform to regulations prescribed by authorities (such as the department of health and/or others) which are in charge of regulating the tobacco processing industry.  
           [0018]    The film can consist, at least in part, of polyvinyl acetate or it can constitute a dispersion of acrylate.  
           [0019]    The at least one conveyor can comprise an endless band which consists, at least in part, of a material exhibiting the characteristics of cautchouc, and such arrangement can further comprise a second band having a surface which confronts the surface of the at least one conveyor and defines therewith a path for rod-shaped smokers&#39; products. The characteristics of the surface of the second band can approximate or match the characteristics of the product-treating surface. Such arrangement can also comprise a second substance which is applied to the second band and serves to retard a weakening or lowering of friction coefficient of the second surface.  
           [0020]    The aforementioned path can constitute a rolling channel, and such arrangement can further comprise means (e.g., a motor-driven pulley or gear or wheel) for moving at least one of the bands relative to the other band. Still further, the arrangement can comprise means (e.g., a drum-shaped or otherwise configurated conveyor) for admitting into the rolling channel a series of successive rod-shaped products each of which bears a sheet-like uniting band which is convoluted around the respective product as a result of rolling movement of the product in the channel. The moving means is preferably set up to move the endless band at a speed which is less than the speed of the second band.  
           [0021]    The smokers&#39; products can include a plurality of rod-shaped articles which are disposed end-to-end, and the uniting bands can be arranged to connect the respective rod-shaped articles to each other as a result of rolling in the channel.  
           [0022]    Another feature of the present invention resides in the provision of a novel article of manufacture which is a conveyor including a layer consisting at least in part of an elastomeric material (such as caoutchouc) and having a transporting surface with a relatively high friction coefficient, and a film which is applied to the conveyor (preferably to the transporting surface) and serves to at least retard a lowering of the friction coefficient, e.g., due to at least intermittent frictional contact of the transporting surface with commodities of sheet-like material including paper (e.g., with tubular envelopes of plain cigarettes, cigars, cigarillos and/or filter mouthpieces).  
           [0023]    The film can contain or consist of polyvinyl acetate or it can constitute a dispersion of acrylate.  
           [0024]    The conveyor can constitute an endless belt or it can constitute a rotary drum-shaped conveyor having a peripheral surface which functions as the aforementioned transporting surface.  
           [0025]    The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved arrangement itself, however, both as to its construction and the modes of assembling and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0026]    The single FIGURE is a fragmentary elevational view of an arrangement for manipulating rod-shaped products of the tobacco processing industry and adhesive-coated uniting bands, e.g., in a filter cigarette making machine.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0027]    The arrangement which is shown in the drawing comprises a rotary drum-shaped conveyor  1  that is driven to rotate in a clockwise direction as indicated by arrow  8  and serves to supply a series of successive equidistant rod-shaped products  2  each of which carries a uniting band  3 . The peripheral surface of the conveyor  1  is provided with axially parallel recesses in the form of flutes  4  each of which transports a product  2  toward a transfer station  6 .  
         [0028]    Each product  2  is assumed to consist of three coaxial rod-shaped articles including two plain cigarettes of unit length and a filter mouthpiece of double unit length between them. Reference may be had again to the aforementioned commonly owned U.S. Pat. No. 5,135,008 to Oesterling et al. One marginal portion of the uniting band  3  adheres to the filter mouthpiece and to the adjacent inner end portions of the two plain cigarettes, and the major part of the uniting band extends substantially tangentially of the product. When the band  3  is convoluted around the product  2 , it constitutes a tube which connects the inner end portions of the plain cigarettes with the filter mouthpiece so that the thus joined rod-shaped components constitute a filter cigarette of double unit length. It is clear that the products  2  can also include pairs of cigars, cigarillos or other tobacco-containing rod-shaped products.  
         [0029]    The drum-shaped conveyor  1  is provided with customary suction ports (not shown) which have intake ends communicating with the flutes  4  and discharge ends connected to a suction generating device (such as a suction pump or the suction intake of a blower) during advancement of flutes from a station which supplies the products  2  to the conveyor to the transfer station  6 . The uniting bands  3  (one side of each of which is coated with a suitable adhesive to facilitate its adherence to the product  2  as well as the conversion into a tube) can be attached to the respective products  2  on the conveyor  1  or prior to entry of such products into the respective flutes  4 .  
         [0030]    Successive products  2  which arrive at the transfer station  6  are taken over by a second rotary drum-shaped conveyor  7  which is driven to rotate in a clockwise direction as indicated by arrow  9  (i.e., counter to the direction of rotation of the conveyor  1 ) and has a peripheral surface  11  provided with axially parallel equidistant projections  12  in the form of ribs or the like which precede suction ports (not shown) serving to attract to the respective ribs  12  those products  2  which arrive at the transfer station  6 . Such suction ports are connected with a suction generating pump or the like during advancement from the transfer station  6  to the inlet A of an elongated straight path constituting a rolling channel  18 . The axis of the drum-shaped conveyor  7  is parallel to that of the conveyor  1 .  
         [0031]    The minimal width of the nip of the conveyors  1  and  7  at the transfer station  6  is selected in such a way that a rib  12  which arrives at this station can expel the product  2  from the immediately adjacent flute  4  and the corresponding suction port(s) of the conveyor  7  then attracts or attract the product  2  to the rib  12  on its way with the conveyor  7  toward the inlet A of the rolling channel  18 .  
         [0032]    The conveyor  7  is provided with additional suction ports (one is shown at  5 ) which attract the nonadherent (uncoated) outer sides of the uniting bands  3  to the peripheral surface of the conveyor  7  in such a way that the uncoated (non-adhesive) sides or surfaces of the uniting bands face away from the axis of the conveyor  7 .  
         [0033]    An endless belt or band conveyor  13  (also known as functional conveyor) is trained over the drum-shaped conveyor  7  and over a third drum-shaped conveyor  19  which is driven by or drives the conveyor  7  and rotates in a clockwise direction as indicated by arrow  22 . The peripheral surface of the conveyor  19  has equidistant axially parallel projections in the form of ribs  23  which cooperate with suction ports (not shown) to engage and entrain successive finished rod-shaped commodities  10  arriving at the outlet B of the rolling channel  18 . The arrow  16  indicates the direction of advancement of the lower reach or stretch of the belt or band conveyor  13  from the inlet A to the outlet B of the rolling channel  18 .  
         [0034]    A drum-shaped take-off conveyor  24  is provided to accept, in its axially parallel peripheral flutes  26 , successive finished rod-shaped commodities  10  from the conveyor  19  at a transfer station  25 . The flutes  26  communicate with suction ports (not shown) which are connected with a suction generating device (e.g., a pump, such as the pump which draws air from the ports of the conveyor  1  and/or  7  and/or  19  in certain angular positions of such ports) as soon as they arrive at the transfer station  25 . The conveyor  24  can deliver the commodities to a testing station, to a severing or subdividing station where the products  10  are halved into pairs of filter cigarettes of unit length, into storage, to a packing station or to another destination.  
         [0035]    The illustrated arrangement further comprises a second endless belt or band conveyor (functional conveyor)  14  which is trained over pulleys  20  and  21 ; one of these pulleys is driven in a counterclockwise direction by a variable-speed motor or transmission so that the upper reach of the conveyor  14  advances in the direction of arrow  17  at a speed different from that of the lower reach of conveyor  13  but in the same direction (arrow  16 ). The neighboring reaches of the conveyors  13 ,  14  are parallel to each other and define the aforementioned rolling channel  18 .  
         [0036]    In accordance with a feature of the present invention, at least one of the conveyors, such as the conveyor  14 , is made and treated in a manner to prolong its useful life, i.e., to ensure that its outer side has an unchanging optimum (relatively high) friction coefficient for long periods of time. To this end, the outer side of the conveyor  14  is provided with a relatively thin film  15  of a material which at least partially closes and/or seals the pores in the outer side. Such outer side is the exposed surface of a layer of caoutchouc which is the material of the conveyor and forms an outer layer along the material of the conveyor  14 .  
         [0037]    The film  15  reduces the friction coefficient of the caoutchouc layer from a relatively high value to a lower value which is best suited to ensure optimal frictional engagement between cigarette paper (i.e., the wrapper of each plain cigarette) and tipping paper (the material of the uniting band  3 ) on the one hand, and the outer side of the caoutchouc layer on the other hand. The film  15  further ensures that the conveyor  14  does not gather minute fragments of paper, chalk and/or other material which are contained in the atmosphere within the rolling channel  18 , adjacent the lower reach of the conveyor  14 , at the pulley  20  (between the nine and twelve o&#39;clock positions) and the pulley  21  (between the twelve and six o&#39;clock positions). Actually, the film  15  does not affect or does not unduly affect the paper dust repellent characteristics, i.e., such characteristics remain unchanged or are altered only to an extent which does not enable the external surface of the conveyor  14  to gather any or to gather excessive amounts of dust.  
         [0038]    The speed of the conveyor  14  is less than that of the conveyor  13  so that a product  2  entering the rolling channel  18  at the inlet A is compelled to roll counterclockwise and to move sideways in the direction of arrow  17 , i.e., toward and beyond the outlet B. This causes a conversion of the uniting bands  3  into tubes which surround the entire mouthpieces and also those portions of the plain cigarettes which are adjacent the mouthpieces.  
         [0039]    The number of revolutions of the products  2  about their respective axes during sidewise movement from the inlet A to the outlet B of the rolling channel  18  depends upon the difference between the speeds of the conveyors  13  and  14 , i.e., such number can be altered by the simple expedient of changing the speed of at least one of these functional conveyors.  
         [0040]    The just discussed conditioning of the conveyor  14  can be replaced or accompanied by similar or analogous conditioning of the conveyor  13 . Still further, each of the conveyors  13  and  14  can be subjected to the aforementioned treatment, i.e., each of these conveyors can carry a layer of caoutchouc and a film  15  of friction coefficient-influencing and dust repelling material.  
         [0041]    The peripheral speed of the drum-shaped conveyor  19  is higher than the speed of the belt conveyor  14  to thus ensure predictable engagement of successive finished products  10  with successive ribs  23  arriving at the outlet B of the rolling channel  18 .  
         [0042]    A presently preferred material for the film  15  is polyvinyl acetate or a dispersion of acrylate which is sprayed onto the layer of caoutchouc. Such material has been found to impart to the caoutchouc layer an optimal friction coefficient which remains unchanged or changes negligibly for a long period of time as well as to enhance the dust-repellent characteristics of the layer. The dust can include minute particles of paper, chalk and other pore-filling substances which develop in a tobacco processing plant in the region of a filter cigarette making machine.  
         [0043]    The thickness of the film  15  on the surface of the caoutchouc layer borne by or forming part of the conveyor  14  should be selected with a view to ensure that the outline of the exposed surface of the layer remains at least substantially unchanged, i.e., that the exposed surface of the layer exhibits the desirable crevices and analogous recesses, cracks or interstices which impart to the layer the desirable coarseness enabling the conveyor  14  to roll the products in the channel  18  with an optimum degree of predictability. At the same time, the film  15  should ensure that the particles of paper, chalk or the like cannot adhere to the exposed surface of the belt conveyor  14 , i.e., that the friction coefficient at the exposed surface of this conveyor remains unchanged for long periods of time. Still further, the application of the film  15  to the caoutchouc-coated surface of the conveyor  14  should be in conformance with the provisions of authorities which are in charge of (i.e., which regulate) the tobacco processing industry. Such regulations exist, for example, in Federal Republic Germany.  
         [0044]    It has been ascertained that a film  15  which meets the above-enumerated desiderata can consist of polyvinyl acetate. Another suitable material which can be utilized for the making of a highly satisfactory film  15  is a dispersion of acrylate. An advantage of acrylate films is that their adherence to the layers of caoutchouc or the like is even more satisfactory than that of polyvinyl acetate; that they are insoluble in water; and that they render it possible to adjust the friction coefficient at the exposed surface of the caoutchouc layer with a high degree of accuracy.  
         [0045]    The improved arrangement can be put to use in a filter cigarette making machine in a manner as described in connection with the drawing (i.e., to roll adhesive-coated uniting bands around two or more coaxial rod-shaped products), as well as in many other fields. For example, a film of polyvinyl acetate or acrylate can be applied to a drum-shaped or belt-shaped conveyor which is to transport continuous webs or strips of cigarette paper or tipping paper as well as discrete uniting bands and/or the like from a suitable source to a conveyor or between a pair of conveyors or the like.  
         [0046]    The peripheral surface of a drum-shaped rotary pulley or conveyor can be provided with a layer of caoutchouc and thereupon with a film of polyvinyl acetate, acrylate or the like, the same as described with reference to the belt conveyor  14 . The purpose of such treatment of drum-shaped conveyors is the same as that of the treatment of exposed product-contacting surfaces of belt conveyors or other types of conveyors, namely to ensure that the friction coefficient at the peripheral surface of the drum-shaped conveyor can assume and remain at an optimum value.  
         [0047]    Referring again to the drawing, the friction coefficient at the exposed surface of the belt conveyor  14  is or can be higher than that at the exposed surface of the conveyor  13 ; this ensures predictable advancement and predictable rolling of products  2  during transport from the inlet A to the outlet B of the rolling channel  18 . Thus, each product  2  can complete a single revolution or a desired number of (plural) revolutions about its own axis while it advances sideways from the six o&#39;clock position of the drum  7  to the six o&#39;clock position of the drum  19 .  
         [0048]    The aforedescribed features and advantages of the improved conveyors or groups of improved conveyors contribute significantly to superior quality of the ultimate products as well as to savings in tobacco, plain cigarettes, filter mouthpieces, cigarette paper and tipping paper because the number of rejects can be reduced to a minimum. Such advantages can be achieved in spite of slight initial reduction of nonskid properties of the conveyor due to application of the film  15  to the exposed surface of the caoutchouc layer. The reason is that such slight initial reduction of the friction coefficient is more than compensated for by a pronounced slowing down of a reduction of the friction coefficient of the belt conveyor  14  in actual use of such conveyor or of an equivalent thereof, e.g., a drum.  
         [0049]    Another advantage of the aforedescribed undertakings is that they can be resorted to for restoring the utility of conventional conveyors, particularly belt or band conveyors, which lack a film of polyvinyl acetate, acrylate or the like and can no longer be used in the required manner due to clogging of the pores in the caoutchouc layer by minute fragments (such as dust) of cigarette paper, tipping paper or other minute impurities. The utility of such dust-laden conveyors can be restored by the application of a film  15  and/or other films to the contaminated layer of caoutchouc or the like.  
         [0050]    Still further, it is possible to restore the utility of conveyors wherein a layer of caoutchouc carries a film  15  and which, after an extended period of use, carry a coat of paper dust, chalk and/or the like. All that is necessary is to clean the film and to apply a fresh film over the cleaned film.  
         [0051]    Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of the above outlined contribution to the art of making conveyors for rod-shaped articles and the like and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.