Patent Publication Number: US-2005126129-A1

Title: Product packing assembly for packing food products

Description:
The present invention relates to a product packing assembly, in particular for packing food products, to which the following description refers purely by way of example.  
     BACKGROUND OF THE INVENTION  
      Packing systems, commonly referred to as “flow-pack” systems, are known, in which the products for packing are arranged spaced apart in a line inside a tube, which is made of a film of packing material, and is fed through sealing and cutting stations to seal and separate packages, each containing a respective product.  
      To seal and cut the tube, a need is felt for a “tracking” system—i.e. a system in which a carriage supports the packing tools and runs back and forth parallel to the tube—to enable precise, versatile packing regardless of the distance between the products.  
      More specifically, a need is felt for a tracking-type packing assembly which is relatively straightforward and provides for accurate positioning of the packing tools.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a product packing assembly, in particular for packing food products, designed to meet the above demand in a straightforward, low-cost manner.  
      According to the present invention, there is provided an assembly for packing products, in particular food products, arranged successively and spaced longitudinally apart inside a tube of packing material traveling along a respective longitudinal axis comprising: 
          a carriage movable back and forth, parallel to the longitudinal axis, along a forward stroke in the same direction as the travel of the tube, and along a return stroke in the opposite direction to the travel of the tube;     a first tool carried by the carriage and movable, with respect to the carriage, to perform, along each the forward stroke, a first packing operation on the tube;     at least one second tool, which differs from the first tool, is carried by the carriage, and is movable, with respect to the carriage, to perform, along each the return stroke, a second packing operation on the tube; and     actuating means for moving the first and the second tool, respectively, to perform the first and the second packing operation respectively, wherein at least some of the actuating means are carried by the carriage.       

    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which:  
       FIGS. 1 and 2  show, respectively, a front view in perspective and a rear view in perspective of a preferred embodiment of the assembly for packing products, in particular food products, according to the present invention;  
       FIG. 3  shows a front view, with parts removed for clarity, of the  FIG. 1  assembly;  
       FIG. 4  shows a schematic, partly sectioned side view of the  FIG. 1  assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Number  1  in  FIGS. 1 and 2  indicates an assembly for packing products  2  using a so-called “flow-pack” system. Products  2 , e.g. food products such as snacks or sliced bread, are arranged successively and spaced apart inside a “tunnel” or tube  3  (shown partly in  FIG. 3 ), which is made of packing material, e.g. plastic film, has an axis  4 , and is fed, together with products  2  and on a horizontal supporting surface (not shown), along axis  4  in the direction of arrow A by a known drive device not shown.  
      Assembly  1  comprises a fixed, flat supporting wall  9  parallel to axis  4  and having a straight intermediate slot  10  also parallel to axis  4 . Wall  9  supports a “tracking” device  12  comprising an actuating device  13 ; and a carriage  14 , which is fitted to the front face of wall  9 , on two straight rails  15  located on opposite sides of slot  10 , to run back and forth, under the control of device  13  and in a direction B parallel to axis  4 , along a forward stroke in the same direction as arrow A, and a return stroke in the opposite direction to arrow A. The travel of carriage  14  is defined by two stops  16  fixed to wall  9  ( FIG. 3 ), and is controlled by a switch device  17  ( FIG. 4 ) fitted to the rear face of wall  9  and activated by a corresponding member  18  integral with carriage  14 .  
      With reference to  FIG. 2 , device  13  is fitted to the rear face of wall  9 , and comprises a rotary electric motor  19  fixed to wall  9 ; and a belt transmission  20 , in turn comprising a driven pulley  21  and a drive pulley  22  with respective axes perpendicular to direction B and parallel to wall  9 . More specifically, pulley  22  is coaxial with motor  19 .  
      Transmission  20  comprises a belt  26  looped about pulleys  21 ,  22  and fixed to a plate  27 , which is integral with carriage  14 , projects through slot  10 , and supports member  18 .  
      With reference to  FIGS. 1 and 3 , assembly  1  also comprises two slides  28 ,  29 , in turn comprising respective rear plates  30 ,  31 , which are coplanar with each other and fitted to carriage  14  on straight guides  32  to slide in a direction C perpendicular to direction B and parallel to wall  9 .  
      Slides  28 ,  29  are moved back and forth linearly in opposite directions by an actuating device  34  carried by carriage  14  and comprising a rotary electric motor  35  fixed to carriage  14  and having an output axis  36  perpendicular to directions B and C.  
      Device  34  also comprises two connecting rod and crank transmissions  37 ,  38 , in turn comprising respective cranks  39 ,  40 , which are diametrically opposite with respect to axis  36 , and form part of the same rocker arm lever  41  which is oscillated about axis  36  by motor  35 . Transmissions  37 ,  38  also comprise respective connecting rods  42 ,  43 , which are of different lengths and connected by spherical end joints to plates  30 ,  31  at one end, and to cranks  39 ,  40  at the other end.  
      With reference to  FIGS. 1 and 4 , slides  28 ,  29  also comprise respective arms  44 ,  45 , which project from plates  30 ,  31 , are located on opposite sides of the path of tube  3 , and support respective heads  46 ,  47  facing each other in a direction D parallel to direction C. Head  46  is fixed to arm  44 , while head  47  is fitted to arm  45  by means of two guides  48 , so as to move in direction D in opposition to the elastic action of two packs  50  of springs, which are associated with respective guides  48 , are therefore parallel to each other, and comprise respective numbers of disk springs  51 .  
      Head  47  comprises two side by side corresponding portions  52  defining a slit  53  perpendicular to axis  4 ; and head  46  comprises two sealing members  54  (only one shown in  FIG. 4 ) which cooperate with respective portions  52  and are located on opposite sides of a knife  55 , which is aligned with slit  53  and fitted to arm  44  to move in direction D under the control of an actuating device  56  housed inside arm  44  and therefore movable together with slide  28  and carriage  14 .  
      With reference to  FIG. 4 , device  56  comprises a fluidic actuator, in particular a pneumatic cylinder  57 ; and an articulated-parallelogram transmission  58 , which is activated by cylinder  57 , when heads  46 ,  47  grip tube  3 , to move knife  55  between a withdrawn position inside head  46 , and an extracted position inside slit  53 , to separate two successive packages  59 , after an edge  60  between packages  59  has been sealed between members  54  and portions  52 .  
      With reference to  FIGS. 1 and 3 , assembly  1  also comprises an additional air expulsion device  61  located downstream from heads  46 ,  47  in the direction of arrow A, and comprising two facing, respectively top and bottom, pressure members  62 ,  63 , and two pneumatic cylinders  64 ,  65 , the housings  66 ,  67  of which are fixed to slides  28 ,  29  respectively, and the rods  68 ,  69  of which are coaxial with each other along an axis E parallel to direction D. Member  62  is defined by a plate integral with the end of rod  68 ; and member  63  comprises a support  70  integral with the end of rod  69 , and two rollers  71 , which have respective axes perpendicular to axes  4  and E, rotate idly with respect to support  70 , and are located side by side along axis  4 . Rods  68 ,  69  are movable axially between a withdrawn position, in which device  61  is deactivated and rollers  71  simply define a support for packages  59 , and an extracted position (not shown), in which cylinders  64 ,  65  define respective gas springs.  
      In actual use, carriage  14  is moved along the forward stroke to reach the same traveling speed as tube  3 , while motor  35 , cylinders  57 ,  64 ,  65 , and any sensors (not shown) of assembly  1  are powered electrically and/or pneumatically by flexible wiring not shown.  
      On reaching zero relative speed between carriage  14  and tube  3 , motor  35  is operated to rotate lever  41  (anticlockwise in  FIG. 3 ), so as to move slides  28 ,  29  towards each other and bring heads  46 ,  47  into contact with tube  3  in an intermediate position between two consecutive products  2 . By virtue also of the elastic action of packs  50  of springs, tube  3  is gripped between heads  46 ,  47  and sealed by members  54  along two portions defining the edges  60  of two successive end packages  59  along axis  4 .  
      Shortly after the sealing operation, while tube  3  is still gripped by heads  46 ,  47 , a cutting operation may be performed by extracting knife  55  towards slit  53  to separate the two packages  59 . During the cutting operation, packs  50  of springs act as shock-absorbers, in the event knife  55  strikes the bottom of slit  53 . Once two consecutive products  2  are packed, slides  28 ,  29  are parted by reversing motor  35 , carriage  14  is reversed by reversing motor  19 , and the same packing operations are repeated on the next portion of the tube.  
      For some types of products and packages (e.g. when packing sliced bread), air must be expelled from an empty portion of tube  3  (i.e. containing no products  2 ) at the end of a package  59  before it is sealed. In which case, device  61  is activated to move out rods  68 ,  69 , so that, as slides  28 ,  29  move towards each other, and before heads  46 ,  47  contact tube  3 , members  62 ,  63  grip and expel the air from the empty portion, while rollers  71  assist relative travel between tube  3  and members  62 ,  63  to avoid tearing or creasing tube  3 .  
      By the end of the approach movement of slides  28 ,  29 , the gas springs of device  61  are fully compressed, and tube  3  is gripped between heads  46 ,  47  and sealed and cut in the same way as described above.  
      As will be clear from the foregoing description, assembly  1  comprises a small number of component parts, and, since devices  34 ,  56 ,  61  move together with carriage  14  and are extremely straightforward, provides for accurately positioning the packing tools defined by members  54 , knife  55 , and members  63 ,  63 . Assembly  1  itself is also extremely straightforward and relatively compact, by virtue also of the location of devices  34 ,  56 ,  13 , the particular type of transmission  20  used, and the linear reciprocating movement of carriage  14 , slides  28 ,  29 , and knife  55 .  
      By controlling motor  19 , movement of the carriage can be regulated to adapt the packing system to products  2  of different types and sizes; and motor  35 , cylinder  57  and cylinders  64 ,  65  may be controlled independently to either only seal the tube (to form a continuous strip of packages  59 ) or also perform the cutting and/or air expulsion operations.  
      Clearly, changes may be made to assembly  1  as described herein without, however, departing from the scope of the present invention.  
      In particular, heads  46 ,  47  may be of various types, e.g. induction, resistance, or ultrasound heat-seal heads, and/or knife  55  may be replaced by a different package separating tool, e.g. for forming a continuous or perforated tear line. The packing operations performed by assembly  1  may differ from those described, e.g. may comprise printing the packing date, and/or articles other than food products  2 , referred to by way of example, may be packed.  
      One of devices  34 ,  56  may be fixed to wall  9 , as opposed to being carried by carriage  14 , and/or transmissions  20 ,  37 ,  38 ,  58  may differ from those described, e.g. may be cam or lever types, and/or movement of the packing tools may be curved and/or crosswise to axis  4 , and/or slide  29  may be fixed with respect to carriage  14 .