Abstract:
An apparatus for packaging stacks of folded paper products such as handkerchiefs or the like with blanks of plastic film, comprising at least one pocket ( 58 ), insertion means ( 5 ), along an insertion direction, of a single stack in said pocket ( 58 ) with the interposition and consequent folding of a corresponding blank, said pocket ( 58 ) being operatively associated with stop means ( 24 ) of the stack completely inserted within said pocket. There are control means ( 22 ) adapted to operate the stop means ( 24 ) in a coordinated manner with respect to the operation of the insertion means ( 5 ), to provide an abutment to the stack during the whole insertion step in the pocket ( 58 ), the stop means ( 24 ) comprising suction means ( 72 ) adapted to keep the film in position and to disengage the same film at least in an extraction step of the stack from the pocket.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention concerns the packaging of stacks of folded tissue items such as handkerchiefs, napkins and the like with a wrapper made from weldable plastic film, for example but not exclusively through revolving drum machines. 
       BACKGROUND OF THE INVENTION 
       [0002]    Known machines or apparatuses of this type are of the kind described in U.S. patents U.S. Pat. No. 4,845,924 and U.S. Pat. No. 5,459,979. In brief, these are high speed packaging machines, comprising a drum provided with radial pockets with dimensions that are suitable for the product to be packaged, inside which the stacks of product to be packaged are inserted in rapid succession, with the simultaneous interposition of one blank plastic film, so as to obtain the complete wrapping of each stack, completed by welding applied on the film to obtain a closed packaging. 
         [0003]    In machines of this kind, due to the high operation speed that is required to ensure suitable productivity, it is very complex to compress the stack, keep its correct geometry and carry out the insertion inside the pockets of the drum without causing deformations or faults in the wrapping by the film. In particular, but not exclusively, it is difficult, if not impossible, to keep control of the position of the film and of the compression in the radial direction of insertion during the wrapping step when the speed increases beyond a certain limit, causing defects in the package which, in any case, can occur also when the speed is kept below said limit. 
       SUMMARY OF THE INVENTION 
       [0004]    There is thus the problem of feeding stacks of paper tissue products that can be compressed in packaging machines like those of the aforementioned type, exceeding the productivity limits currently imposed by the prior art, keeping the correct geometry of the group or stack of products, as well as the control of the compression (in the radial insertion direction) and of the position of the film in the wrapping step, all with constructive solutions that are relatively simple and reliable. 
         [0005]    The solution of such a problem is achieved with the unit and method according to the present invention, the essential characteristics of which are defined by the first and by the thirteenth of the attached claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The characteristics and the advantages of the unit and method according to the present invention shall become apparent from the following description of an embodiment thereof, given as an example and not for limiting purposes, with reference to the attached drawings, in which:: 
           [0007]      FIG. 1  is a schematic side view of a packaging machine according to the invention, complete with all its devices; 
           [0008]      FIG. 1   a  represents an enlarged view of the zone that is circumscribed by the circle I of  FIG. 1 , with parts removed for the sake of clarity of the illustration; 
           [0009]      FIG. 2  is a schematic top plan view of the machine of  FIG. 1 ; 
           [0010]      FIG. 3  is a schematic side view like that of  FIG. 1  but showing only the devices for feeding, compressing and inserting the stacks and the packaging drum; 
           [0011]      FIG. 4  and  FIG. 5  are respectively side and top plan views of an upper oscillating arm of the feeding device of the machine of the previous figures; 
           [0012]      FIG. 6  and  FIG. 7  are respectively a side and a top plan view of a lower oscillating arm of the feeding device of the machine of the previous figures; 
           [0013]      FIG. 8  is a cross-section view of the feeding device, with the upper and lower arms that are sectioned respectively along section lines B and A of  FIGS. 4 and 6 ; 
           [0014]      FIG. 9  schematically depicts the movements of the upper oscillating arm of the feeding device in the various operating steps, in side view; 
           [0015]      FIG. 10  and  FIG. 11  are respectively a top plan and front schematic view of a device for inserting the film and extracting the products; 
           [0016]      FIGS. 12 and 13  are respectively a side view and a front view of a stop plate cooperating with the device according to the two previous figures; 
           [0017]      FIGS. 14 ,  15  and  16  are respectively a schematic side view, a schematic top plan view and a schematic front view of the device for feeding the stacked products, with vertical product inlet; 
           [0018]      FIG. 17  and  FIG. 18  are a side view and a front view of a feeder cylinder of the stacks of products, belonging to the feeding device according to the previous figures; 
           [0019]      FIG. 19  is a schematic side view of the stack feeding device with a horizontal product inlet; 
           [0020]    Figures from  20   a  to  20   g  are side views of the packaging machine according to the invention in the various operating steps, from the insertion of a stack of products into the compression device to the outlet of the packaged products. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    With reference to said figures, and in particular to  FIGS. 1 ,  1   a  and  3 , a packaging machine or apparatus according to the invention comprises a device  1  for inserting the product (stacks  3  of folded products to be packaged) into a feeding system. A couple of belts  2 , coming from a folding machine upstream, feed the product to the inserting device  1 , along a direction that is orthogonal to the drawing sheet, taking here as a reference the way the machine is displayed in the figures. 
         [0022]    A device generally indicated with reference numeral  4  is intended for feeding the stacks  3  to a compression device or system  8 . The feeding occurs along a plane  35  that is inclined with respect to the horizontal, typically by about 10°.  FIG. 3  particularly shows belts  50  for the pre-compression and the feeding of the stacks  3  in the device  4 , a couple of deviation rollers  52  of the belts  50  that can be adjusted in height as a function of the product to be packaged, and a stack  3  of products that have been pre-compressed in the insertion step into a compression device  8  arranged downstream. 
         [0023]    It can also be noted the provision of: a device  5  for the radial insertion of the stacks  3  in a packaging drum  21  equipped with pockets  58  radially formed with an adjustable width as a function of the product to be packaged; an upper oscillating arm  6  for the insertion of the stacks in the drum  21 ; and a lower oscillating arm  7  that slidably supports, along its axis, the aforementioned device  8  for compressing the stacks comprising a lower compression plate  9  with a reciprocating motion in a direction that is orthogonal with respect to the axis of the arm  7 . A front plate  10  for stopping the stacks  3  is in turn reciprocating along a direction orthogonal to that of the lower arm  7 , when it is in the position of bottom dead centre, in this case independently from the same arm. A support  11  of the stop plate  10  is indeed fixedly connected through a linkage  34   a  to a basement  34  of the machine (see  FIG. 2 ). 
         [0024]    A multiple cam upper actuation device  12  drives: a first crank and rod upper device  13  for controlling the insertion device  5  of the stacks  3 , i.e. to displace the device  5  along the arm  6 ; a second crank and rod upper device  14  for radially controlling a mobile cam portion  22  intended also, as made clearer hereafter, for inserting the plastic packaging film; and a third crank and rod upper device  15  for controlling the radial displacement, i.e. along the arm  7 , of the device  8  for compressing the stacks. 
         [0025]    A multiple cam lower actuation device  16  drives: a first crank and rod lower device  17  for controlling the lower compression plate  9  of the stacks  3 ; a second crank and rod lower device  18  for controlling the front stop plate  10  of the stacks  3 ; a third crank and rod lower device  19  for controlling the rotation of the lower oscillating arm  7 ; and a fourth crank and rod lower device  20  for controlling the rotation of the upper oscillating arm  6 . 
         [0026]    Both cam actuation devices actually provide for a mechanism that comprises an eccentrically rotating disc, peripherally defining a cam surface with which a crank comes tangentially into contact. The crank is hinged at an end, and contacts the cam surface at a crank intermediate point, so that the same crank is driven in oscillation, around the hinging point, in response to the rotation of the disc. The rods linking the cranks to the various controlled devices are in turn pivotally connected, respectively, to the same devices, and to the cranks in predetermined points comprised between the crank intermediate point of contact with the disc, and a free end of the crank, all with geometrical characteristics that are suitably set as a function of the mutually coordinated displacements to be carried out. 
         [0027]    The already mentioned mobile cam portion  22  drives extractors  24  that are also designed for assisting the insertion of the film in the pockets  58 . More precisely, the mobile portion  22  represents a radially displaceable end portion (as seen driven by the second upper device  14 ) of a fixed cam  23  evolving according to a curl around the axis of the drum on a side thereof. In practice, the fixed cam  23  of the invention does not run according to a ring, but rather like an open loop, the opening being defined by a circumferential and radial discontinuity (step-like discontinuity) in the film insertion area. The mobile portion  22  is indeed arranged in correspondence with such a discontinuity, and is displaceable radially between a radially external position (guide cam larger diameter) and a radially internal position (guide cam smaller diameter), said displacement driving accordingly the movement of the extractors. In an area  23   a  opposite the discontinuity, the fixed cam  23  then evolves in a continuous manner from the smaller to the larger diameter so as to drive the extractors  24  between a rearward displaced position and a radially extracted position for pushing the packaged stacks  3  out of the pockets  58 . The outlet of the packages from the drum  21  is indicated with reference numeral  25 , still in  FIG. 1 . 
         [0028]    Again in  FIG. 1  it is possible to identify a band of film  29  fed by a cylinder  30  in a continuous manner for packaging the product, and cut in blanks  38  by a cutting cylinder  31  bearing a blade  32 ; finally, a transversal welding system  39  welds the film once wrapped around the stacks  3 . 
         [0029]    With particular reference now to  FIG. 2 , a series of ducts  40  is formed in the drum  21  for the passage of the depression/suction exerted on the periphery of the same drum. The passages  40  are clearly visible and indicated also in  FIG. 3 ; they communicate with a fixed manifold  33  that circumferentially runs along a certain arc, along which the depression must indeed be sequentially transmitted, drawn from an external vacuum source to the purpose of holding the packaging film. Respective bearings  41  carry out the function of a mechanical drive link with the extractors  24 . A transmission shaft  42  connected to the drum  21  is actuated by a motor  43  which also drives a shaft  44  for controlling the film feeding and cutting system. The arms  6  and  7  are coupled with the shaft  42 , but idle therewith, adjacent to one another on one side of the drum, and in the same way there is arranged the mentioned cam  23  which is integral with the base  34 . The same motor  43  also transmits motion to: a shaft  45  for controlling the upper actuation device  12 ; a shaft  46  for controlling the lower actuation device  16 ; a shaft  47  for controlling the stack feeding device  4 ; and finally a shaft  48  for controlling the stack inserting device  1 . 
         [0030]    Going back to  FIG. 3 , reference numerals from  53  to  57  denote various geometrical reference elements for the operation of the machine, according to what shall become clearer further on in the present description. A plane  54  defines the middle of the height  53  of the stacks fed by the device  4 , said plane being thus equidistant from the rollers  52 , and at the same time the middle of the height or opening  56  of the compression device  8  in the step of maximum opening, during the insertion of the product, at the bottom dead centre of the lower arm  7 . A plane  55  moreover corresponds to the middle of the height of compression in the condition of maximum compression and coincides with a diametral plane of the drum  21 . The compression height, indicated with reference numeral  57 , can of course be adjusted as a function of the product to be packaged. 
         [0031]    With particular reference to the figures from  4  to  8 , these show in greater detail the group of the upper and lower oscillating arms  6 ,  7  with the device  5  for the insertion of the stacks, in the form of a bar projecting sideways towards the drum from the upper arm  6  (arranged farthest outside), and the compression device  8  supported cantilevered, again towards the drum, by the lower arm  7  (arranged farthest inside, i.e. adjacent to the drum itself). Obviously, the extension of the arms  6  and  7  is such as to ensure that the devices  5  and  8  face onto the working surface of the drum, i.e. that in which the pockets are formed. 
         [0032]    Again in such figures it can be noted a linkage  60  with the first crank and rod upper device  13 , a linkage  61  with the fourth crank and rod lower device  20  for controlling the upper oscillating arm  6 , a linkage  62  with the third crank and rod upper device  15  for controlling the stack compression device  8 , a linkage  63  with the third crank and rod lower device  19  for controlling the lower oscillating arm  7 , an upper compression plate  64  that can be adjusted as a function of the height of the pockets of the drum and of the stacks to be packaged, and finally a linkage  65  with the first crank and rod lower device  17  for controlling the reciprocating motion of the lower compression plate  9 . 
         [0033]    The movement of the upper oscillating arm  6  in the various operating steps is indeed schematised in  FIG. 9 , together with the various positions correspondingly taken up by the insertion device  5 . As it will be made clearer in detail hereafter, the insertion device  5  moves in practice according to a revolution around the upper compression plate  64 , in a continuous manner without any abrupt motion inversion that could limit the productive speed. 
         [0034]      FIGS. 10 and 11 , on the other hand, show more clearly an extractor  24 , which, as mentioned above, also performs the function of assisting the insertion of the film  38 , with its own bearing  41 . In such figures there can be noted a duct  71  and holes  72  open on a working surface, for the passage of the depression/suction, such a surface being defined by a head  24   a  which represents a stop against which the stacks come into abutment.  FIGS. 12 and 13  are, on the other hand, isolated representations of the front stop plate  10  of the stacks  3 , and it can be noted how it is in turn provided with holes  73  for the passage of the depression/suction. 
         [0035]    Again considering in particular  FIGS. 1 and 3 , a sequential valve  27  is formed in the drum  21 ; such valve is fixedly linked with the fixed cam  23  for controlling the depression on the side of insertion of the film. In practice, in the point where the film is fed on the drum  21  by means of the cylinder  31 , the aforementioned valve activates the suction exerted by the extractors  24 , turning the suction off when the product has been inserted completely, or at about ¾ of the complete insertion run. 
         [0036]    A further sequential valve  26  is in the shape of a crown, which is fixedly connected to the shaft  42  with which the drum  21  is integral, and is activated at about ⅔ of the insertion step, as a result of the movement of the extractors  24 . When the tail end of the extractors  24  abuts on the bottom of grooves defined by the crown valve  26 , the depression exerted by the extractors themselves is turned off. In this way, before the insertion has been completed, due to the depression applied at this point on the end flaps of the blank of film  38  by only the passages  40  of the surface of the drum, there is a return effect of the same film towards the outside with consequent effect of close adhesion to the stack  3 . 
         [0037]    The valve  26 , and in particular the bottom of the relative grooves, can have different diameters to control at which insertion depth one desires to turn the depression off. A depression chamber  28 , which transmits the suction to the extractors  24 , is fed by a vacuum source normally with values that are about double that applied to the manifold  33 , this indeed to ensure a safe positioning of the film during the insertion step. 
         [0038]    With particular reference now to  FIGS. 14 to 18 , a feeding device  4  with vertical inlet thus also comprises a series of stack conveyors  80  linked with a transmission system, a stack front stop plate  81 , a series of stack guides  82  for guiding the stacks in the insertion step, a series of belts  83  and  87  outside the periphery of a conveyor cylinder  85  which can rotate integrally with a shaft  89 , a series of cavities  84  formed in the cylinder  85 , a series of belts  86  inside the cylinder  85 , and a plurality of rollers  88  for controlling and deviating the various belts. The groups of external belts, in each of which two or more belts evolve in parallel, thus include three successive series of external belts, i.e. belts  83  opposing the belts  86  along the portion of vertical or almost vertical inlet, for compressing the stacks so as to keep them in position and aligned, the belts  50  which transport the stacks along the outlet portion, and belts  87  in an intermediate deviation zone between the inlet portion and the outlet portion, so as to keep the stacks in position in the passage from the vertical position to the horizontal one, in adherence with the cylinder  85  from which they are driven. 
         [0039]    In  FIG. 19  an analogous feeding device with horizontal inlet of the product, according to an embodiment that is alternative to the previous one, has a simplified structure with a feeding cylinder  90  without cavities. In the case in which there is horizontal outlet of the stacks from the folding machine upstream, there is no need for cavities since the belt deviation angle is reduced. 
         [0040]    With reference now also and in particular to  FIGS. 20   a  to  20   g , the machine according to the invention operates in the following manner. 
         [0041]    As mentioned, the machine can be arranged for vertical or horizontal feeding, and in any case for a good operation the insertion plane  35  must have a certain inclination with respect to the horizontal, descending towards the drum  21  and preferably equal to about 10°. In such a way the stacks  3 , as shall be comprised more clearly hereafter, adhere to the front stop plate in perfectly perpendicular arrangement with respect to the plane defined by the lower compression plate  9 . 
         [0042]    Starting from the step shown in  FIGS. 1 ,  14  and  20   a , the product stacks  3  are fed by the belts  2 , and at the end of their path they are inserted in the product guides  82  in adherence with the stop plate  81 . The insertion feet  80  have a continuous vertical and horizontal movement with constant speed equal to that of the belts  83  and  86  driven by the cylinder  85  of the feeding device  4 , said belts  83 ,  86  receiving each stack by engaging with it at opposite ends, and also carrying out a slight compression. The stacks in forward displacement movement reach the cavities  84  formed in the cylinder  85 , and after the detachment from the belts  83  they are kept compressed towards the cylinder  85  through the further outer belts  87  which are driven by the same cylinder through friction with its surface. In such a way the correct peripheral speed is maintained without causing the stacks themselves to become deformed. 
         [0043]    When the stacks come out from the cylinder  85 , the belts  50  in cooperation with the internal belts  86  transport the stacks to their insertion in the compression device  8 . The outlet rollers  52  of the belts  50  and  86 , as already mentioned, have an adjustment system for keeping an equidistant position with respect to the middle plane  54  as a function of the height of the product to be packaged. The speed of the belts can vary according to the diameter of the cylinder  85  and to the number of cavities  84  present in the cylinder itself. The stacks in outlet from the belts  50 ,  86  have a compressed height that is about the same as that of the packaged product, and are inserted into the compression device  8  in its condition of maximum opening  56  at the bottom dead centre of the arm  7 . Such a height  56  is normally 50% greater with respect to the height of the stacks in outlet from the belts  50 ,  86 . 
         [0044]    When it is inserted in the compression device ( FIG. 20   b ) the stack expands and becomes adherent with the stop plate  10  which exerts a suction (holes  73 ) ensuring the perfect alignment with the plate itself even of the single folded sheets of paper, before the compression. 
         [0045]      FIG. 20   c  represents the beginning of the compression step. The arm  7  begins its ascending movement, with the compression plate  9  which, having a relative movement that is orthogonal with respect to the arm  7 , arrives at the programmed height and compresses the stack in cooperation with the upper plate  64 . Such a programmed height of course coincides with the height of the pockets  58  of the packaging drum  21  and is maintained until the stack is completely inserted inside the drum. 
         [0046]    The front stop plate  10 , in turn capable of a movement which is orthogonal with respect to the lower arm  7  in the lower end stop position, meanwhile reaches and then keeps its own lower end stop position. At this point the compression device linked to the arm  7  in the condition of maximum compression of the stack carries out a radial displacement along the axis of the same arm until it gets close to the drum  21   
         [0047]    The upper arm  6 , in the meantime, has begun and continued a descending step, rotating around the axis of the drum  21 , until it reaches the bottom dead centre; then the movement is reversed and an ascending step begins. 
         [0048]    Passing on to  FIG. 20   d , the arms  6  and  7  have reached a mutual alignment position that is suitable for allowing the insertion of the stack in a pocket  58  of the drum  21 , and at this point the insertion device  5 , with a radial movement, moves toward the drum until it abuts against the stack of compressed product. Once a position in which the distance from the periphery of the drum corresponds to the width of the stack has been reached, the mobile cam portion  22  also begins a radial movement, i.e. a rearward displacement, accompanying the product in a coordinated manner with the device  5 , so as to keep it orderly secured on two opposite sides, until it has been completely inserted. 
         [0049]      FIG. 20   e  shows the insertion step of the stack  3  with the arms  6  and  7  that rotate in phase with one another and with one of the pockets  58  of the drum  21 . The device  5  proceeds forwards until the stack  3  is completely inserted; in adherence with the stack, by means of the passages  40  connected to a depression source, a blank of film was previously interposed so as to carry out the wrapping, according to a conventional expedient but with some peculiar provisions of the present invention which will result clearer hereafter. The front stop plate  10  returns to its initial condition. 
         [0050]    Passing on now to  FIG. 20   f , the upper arm  6  continues to rise towards the top dead centre, the insertion device  5  keeps its position closest to the drum  21 , and the arm  7  reaches its top dead centre. The compression device  8  carries out a radial abrupt movement away from the drum, until it returns to the starting position, so as to free the space between the upper compression plate  64  of the device  8  and the insertion device  5 . 
         [0051]    Finally, as can be seen in  FIG. 20   g , the lower arm  7  and the compression plate  9  carry out a return movement to the starting position so as to receive a new stack of products. The upper arm  6  arrives at the top dead centre and inverts its movement, whereas the insertion device begins its radial movement along the arm  6  so as to return to the starting position, without interfering, as already mentioned, with the upper compression plate  64  which, being part of the device  8 , is already in position to receive a new stack  3 . The drum  21  continues its rotation with constant speed, in a clockwise direction according to the representation of the figures, and a new packaging pocket  58  proceeds to the point in phase with the arms  6 ,  7 . The system is ready for a new cycle. 
         [0052]    Returning to follow the path of the stacks inside the drum  21 , it should be noted that the control of the stacks, with the film wound in the pockets, is also taken up by the extractors  24  which, due to the movement of the cam portion  22  in the area of insertion, move rearwards thus providing an inner side abutment accompanying the same stacks in their insertion displacement. 
         [0053]    Moreover, the suction exerted by the extractors  24  contributes to keep the stack and the wrapping film in an orderly fashion. When the packet passes in correspondence with the welding system, it is welded and then expelled thanks to the ejection of its extractor driven by the evolution  23   a  of the cam  23  in the area diametrically opposed to that of insertion. The control of the suction/depression exerted by the extractors  24  is synchronised along the appropriate rotation angle of the drum, by means of the valves  26  and  27 . 
         [0054]    The invention offers then a plurality of advantages. The feeding system through belts, which can have variable speed according to the diameter of the drum, ensures a high feeding speed while keeping the phase control of the position of the product, with short insertion time of the stacks in the compression device, with respect to a chain system, due to its capability not to cause the product to slow down. There is also the possibility of vertically or horizontally feeding the stacks, with pre-compression of the stacks before the insertion in the actual compression device so as to limit the width of the movement of the arms  6  and  7 , consequent constructive simplification. 
         [0055]    The stack stop plate  10 , fixedly connected to the basement, with its depression system, for perfectly aligning the stack itself, is in turn capable of ensuring a significant improvement of the insertion operations, for speed, precision and constructive optimisation. More generally speaking, the results achieved with the invention are due to the overall design (structure and kinematism) of the compression and insertion systems, with—among other things—precise control of the axial compression of the stack by means of the insertion device  5 , in cooperation with the extractor  24  and the mobile cam portion  22 . As mentioned, very important is the path control of the insertion device; such path is in practice a planetary revolution around the upper compression plate  64  (see  FIG. 9  and figures from  20   a  to  20   g.  The motion is smooth and continuous, so that the cooperation between the insertion device and the compression plate  64  ensures a perfectly orderly arrangement of the product, with productive speeds that can be kept very high. More generally speaking, the extractor that accompanies the insertion of the stack with a precise position control of the film, via the connection to a depression source, represents a novel and extremely advantageous feature as far as the quality requirements of the packaging are concerned. 
         [0056]    The vertical/horizontal spatial references used above are of course to be interpreted in relation with the most typical operative configuration, and to the orientation represented in the figures, but it is clear that they must not take up any limitative connotation. 
         [0057]    The present invention has been described thus far with reference to its preferred embodiments. It should be understood that other embodiments can exist which pertain to the same inventive core, within the scope of protection of the attached claims.