Abstract:
A method and unit for packing groups of products, whereby each group is fed, at a loading station, to a respective radial first seat of a first wheel, together with a relative blank, which is first folded into a U and then completely about the relative group to form a packed group, which is transferred, at a transfer station, to a respective radial second seat of a second wheel, together with a relative sheet of overwrapping material, which is first folded into a U and then completely about the relative packed group to form an overwrapped group; the blank and the sheet of overwrapping material both being fed successively to a respective same gripper associated with the relative first seat and fitted to the first wheel, downstream from the first seat.

Description:
[0001]     The present invention relates to a method and unit for packing groups of products.  
         [0002]     More specifically, the present invention relates to a method and unit for packing groups of products, of the type in which each group is fed, at a loading station, to a respective first radial seat of a first wheel, together with a relative sheet packing material element, which is first folded into a U and then completely about the relative group to obtain a packed group. This is transferred, at a transfer station, to a respective second radial seat of a second wheel, together with a relative sheet overwrapping material element, which is first folded into a U and then completely about the relative packed group to obtain an overwrapped group.  
         [0003]     Though suitable for groups of products of any type, in particular substantially parallelepiped-shaped products, the present invention is particularly advantageous for use in the tobacco industry, and particularly on packing units of cartoning machines—to which the following description refers purely by way of example—for packing groups of packets of cigarettes in first sheet packing material elements, normally blanks of cardboard or similar, to obtain packed groups defined by cartons of packets of cigarettes, which are subsequently overwrapped in second packing material elements, normally sheets of transparent overwrapping material, to obtain overwrapped groups defined by overwrapped cartons.  
       BACKGROUND OF THE INVENTION  
       [0004]     In packing units of known cartoning machines, each group of packets of cigarettes is fed to the loading station in a substantially radial direction with respect to the first wheel, and the relative blank is fed to the loading station in a direction tangent to the first wheel, is arrested in front of the relative first seat so as to close it, and is inserted inside the first seat by the relative group of packets. Similarly, each sheet of overwrapping material is fed to the transfer station in a direction substantially tangent to the first and second wheel, is arrested in front of the relative second seat so as to close it, and is inserted inside the second seat by the relative carton as this is expelled from the relative first seat into the relative second seat.  
         [0005]     Though almost universally employed, the above packing method has several drawbacks, which increase in importance with the operating speed of the cartoning machine, and which are normally due to the difficulty encountered in controlling the position of the packing materials, as they are inserted inside the relative seats, in confined, mechanically crowded areas such as the loading and transfer stations, to which the packing materials are normally fed by gravity, and in which the blanks and sheets of overwrapping material constituting the packing materials are not normally clamped to position them accurately with respect to the relative groups as they are first inserted inside the relative seats, but are simply arrested against stops, with no possibility of preventing undesired slippage between the packing materials and the groups.  
         [0006]     Moreover, being fed by gravity to the loading and transfer stations, the packing materials must be located over the packing units. This is not normally a problem in the case of sheets of overwrapping material, which are normally cut off massive reels, but is undoubtedly problematic in the case of blanks, which call for using an open-bottom hopper which must be fed continually with stacks of blanks.  
       SUMMARY OF THE INVENTION  
       [0007]     It is an object of the present invention to provide a method of packing groups of products, designed to eliminate the aforementioned drawbacks.  
         [0008]     According to the present invention, there is provided a method of packing groups of products, as claimed in claim  1  and, preferably, any one of the following claims depending directly or indirectly on claim  1 .  
         [0009]     According to the present invention, there is also provided a unit for packing groups of products, as claimed in claim  9  and, preferably, any one of the following claims depending directly or indirectly on claim  9 . 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]     The present invention will be described with reference to the attached drawing, which shows a partial section, with parts removed for clarity, of a preferred embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     Number  1  in the attached drawing indicates as a whole a packing unit of a cartoning machine  2 , the packing unit receiving, at an input  3 , a succession of groups  4  of packets  5  of cigarettes, and comprising an output conveyor  6  for receiving a succession of overwrapped cartons  7 .  
         [0012]     In the example shown, each group  4  forming the content of each carton  7  comprises ten packets  5  arranged in two superimposed rows, is in the form of a rectangular parallelepiped positioned with its longitudinal axis perpendicular to the attached drawing plane, and is fed to unit  1  by a pusher  8  located at a loading station  10  and acting in a substantially horizontal direction  9  parallel to the attached drawing plane.  
         [0013]     Packing unit  1  comprises a packing wheel  11  tangent to loading station  10  and rotating anticlockwise in steps about an axis  12  perpendicular to the attached drawing plane; and an overwrapping wheel  13 , which rotates clockwise in steps about an axis  14  parallel to axis  12 , is tangent to packing wheel  11  at a transfer station  15  diametrically opposite loading station  10  with respect to packing wheel  11 , and is tangent to the input of output conveyor  6  at an unloading station  16  diametrically opposite transfer station  15  with respect to overwrapping wheel  13 .  
         [0014]     Unit  1  also comprises a feed line  17  for feeding blanks  18  of packing material to packing wheel  11  at a feed station  19  located upstream from loading station  10  and between transfer station  15  and loading station  10  in the rotation direction of packing wheel  11 ; and a feed line  20  for feeding sheets  21  of overwrapping material to packing wheel  11  at a feed station  22  located downstream from loading station  10  and between loading station  10  and transfer station  15  in the rotation direction of packing wheel  11 .  
         [0015]     Wheels  11  and  13  are substantially annular wheels, which comprise respective numbers of radially through seats  23  and  24  equally spaced about respective axes  12  and  14  and each for receiving a relative group  4 . More specifically, seats  23  are of even number—four in the example shown—so that, when one seat  23  is located at loading station  10 , another seat  23  is located at transfer station  15 . Similarly, seats  24  are also of even number—eight in the example shown—so that, when one seat  24  is located at transfer station  15 , another seat  24  is located at unloading station  16 .  
         [0016]     Wheels  11  and  13  are also fitted centrally with respective push devices  25  and  26  aligned with each other and with loading station  10 , transfer station  15 , and unloading station  16 . More specifically, push device  25 , located centrally with respect to packing wheel  11 , comprises two opposite, aligned, radial pushers  27   a  and  27   b , which are movable respectively through a seat  23  at loading station  10 , and a seat  23  at transfer station  15 . Similarly, push device  26 , located centrally with respect to overwrapping wheel  13 , comprises two opposite, aligned, radial pushers  28   a  and  28   b , which are movable respectively through a seat  24  at transfer station  15 , and a seat  24  at unloading station  16 .  
         [0017]     Each seat  23  on packing wheel  11  is fitted at its outer end with a number of retaining members  29 , each of which comprises, in known manner, an end tooth, and which are movable, under the control of a known cam device not shown, between an open rest position, and a closed work position in which they releasably retain a relative group  4  inside seat  23 . Each seat  23  is also associated with a respective gripper  30  located downstream from seat  23  in the rotation direction of packing wheel  11 , and comprising a jaw  31 , which faces rearwards in the rotation direction of packing wheel  11 , projects outwards with respect to a cylindrical outer surface  32  of packing wheel  11 , and is rotated, under the control of a known cam device (not shown) and about a relative axis substantially coincident with a respective generating line of cylindrical surface  32 , between a closed work position contacting cylindrical surface  32 , and a normal open position.  
         [0018]     Feed line  17  for supplying blanks  18  of packing material comprises a manipulator  33 , in turn comprising a disk  34  rotating about an axis parallel to axis  12 , and supporting a given number of pneumatic gripping heads  35 , each of which is orientable with respect to disk  34  about a respective axis  36  parallel to axis  12 , and is movable with disk  34  between a gripping position, in which gripping head  35  contacts the top blank  18  of packing material in a stack  37  of blanks  18  of packing material located beneath packing wheel  11 , and a release position, in which gripping head  35  is located at feed station  19  to feed a front edge of the blank  18  of packing material removed off stack  37  to a gripper  30  arrested at feed station  19  with its jaw  31  in the open position.  
         [0019]     Feed line  20  comprises a number of guide pulleys  38  for a continuous strip  39  of overwrapping material unwound off a reel (not shown) in a direction  40  by pull exerted on strip  39  by a feed unit  41  via a known well-type pneumatic tensioning device  42 . Feed unit  41  comprises, in succession in direction  40 , two opposite, counter-rotating traction rollers  43  engaging strip  39 ; a cutting assembly  44  for cutting strip  39  transversely into a succession of sheets  21  of overwrapping material; and a feed assembly  45  for feeding a sheet  21  of overwrapping material cut off strip  39  to feed station  22 . In the example shown, feed assembly  45  comprises two pairs of guide rollers  46  for said sheet  21  of overwrapping material; and a suction roller  47  tangent to cylindrical surface  32  at feed station  22 , and circumferentially grooved to permit passage through feed station  22  of grippers  30  in the open position.  
         [0020]     When a seat  23  is arrested at loading station  10 , the adjacent seat  23 , downstream in the rotation direction of packing wheel  11 , is arrested at a packing station  48  located upstream from feed station  22 . At packing station  48 , packing wheel  11  cooperates with a known folding device  49  which oscillates, about an axis  50 , between a raised rest position, and a lowered work position in which folding device  49  performs a sequence of operations explained later on.  
         [0021]     At transfer station  15 , wheels  11  and  13  cooperate with a further known folding device  51  which comprises a movable folder and a fixed folder located on opposite sides of transfer station  15  to perform the functions described later on.  
         [0022]     As they travel from transfer station  15  to unloading station  16 , seats  24  are arrested at a succession of sealing stations  52  for performing the functions described later on.  
         [0023]     In actual use, when an empty seat  23  is arrested at loading station  10 , the gripper—hereinafter indicated  30   a —associated with the seat  23 —hereinafter indicated  23   a —preeciding it in the rotation direction of packing wheel  11  is arrested in the open position at feed station  19 .  
         [0024]     Operation of packing wheel  11  will now be described with reference to seat  23   a  and relative gripper  30   a , as these are fed in steps to transfer station  15 .  
         [0025]     When gripper  30   a  is arrested in the open position at feed station  19 , manipulator  33  is activated to withdraw a blank  18  of packing material off stack  37  and feed it to feed station  19  so that a front edge of blank  18  of packing material is inserted beneath jaw  31  of gripper  30   a , which is then closed to clamp blank  18  of packing material to packing wheel  11  so that blank  18  of packing material projects rearwards with respect to gripper  30   a  and in front of seat  23   a.    
         [0026]     At this point, packing wheel  11  advances one step to feed blank  18  of packing material past and into contact with a gumming device  53 , and to arrest seat  23   a , closed outwards by blank  18  of packing material, at loading station  10 . Pusher  27   a  is then moved through seat  23   a  into contact with the surface of blank  18  of packing material facing cylindrical surface  32 , and pusher  8  is activated to feed a group  4  into contact with the outward-facing surface of blank  18  of packing material, so as to clamp blank  18  of packing material against pusher  27   a  and with respect to group  4 , and is then moved further, together with pusher  27   a  and after gripper  30   a  is opened, to insert group  4  and blank  18  of packing material inside seat  23   a.    
         [0027]     Insertion of group  4  inside seat  23   a  folds blank  18  of packing material into a U about group  4 , and then closes retaining members  29 , which retain group  4  and relative blank  18  of packing material inside seat  23   a  and, at the same time, fold and glue, in known manner one on top of the other, two end portions of blank  18  of packing material projecting radially from seat  23   a , to form a tubular package about group  4 .  
         [0028]     A further step forward of packing wheel  11  feeds seat  23   a  to packing station  48 , and gripper  30   a , in the open position, to feed station  22 .  
         [0029]     At packing station  48 , folding device  49 , initially in the raised rest position, is moved into the lowered work position to close the ends of said tubular package in known manner and form a carton  54  inside seat  23   a . At the same time, at feed station  22 , suction roller  47  feeds a front edge of a sheet  21  of overwrapping material beneath jaw  31  of gripper  30   a , which is then closed to clamp sheet  21  of overwrapping material to packing wheel  11  so that, as packing wheel  11  advances another step to feed seat  23   a  and relative carton  54  to transfer station  15 , sheet  21  of overwrapping material projects rearwards with respect to gripper  30   a  and in front of seat  23   a.    
         [0030]     Since each step of packing wheel  11 , equal to the distance between two adjacent seats  23 , corresponds to a step of overwrapping wheel  13 , equal to the distance between two adjacent seats  24 , and since seats  23  and  24  are synchronized at transfer station  15 , seat  23   a , on reaching transfer station  15 , is arrested facing a corresponding seat  24 —hereinafter indicated  24   a —through which pusher  28   a  moves outwards into contact with the outer surface of sheet  21  of overwrapping material. Pusher  28   a  is then moved, together with pusher  27   b , to extract carton  54  from seat  23   a  and insert it, together with sheet  21  of overwrapping material and after gripper  30   a  is opened, inside seat  24   a , so that sheet  21  of overwrapping material is folded into a U about carton  54 , with two lateral portions projecting radially from relative seat  24   a . The two lateral portions are folded one onto the other in known manner by folding device  51  to form a tubular overwrapping about carton  54 , and are sealed gradually in known manner to each other as seat  24   a  is fed in steps through sealing stations  52 .  
         [0031]     As seat  24   a  is arrested at unloading station  16 , pusher  28   b  is activated to transfer carton  54  to output conveyor  6 . As carton  54  and the relative tubular overwrapping are transferred and subsequently fed along an initial portion of output conveyor  6 , the ends of the tubular overwrapping are closed in known manner to form an overwrapped carton  7 .  
         [0032]     In connection with the above, it should be pointed out that, by providing each seat  23  on packing wheel  11  with a respective gripper  30  located in a given position downstream from seat  23  along cylindrical surface  32 , and for receiving both a relative blank  18  of packing material and a relative sheet  21  of overwrapping material, blanks  18  of packing material and sheets  21  of overwrapping material are positioned correctly at all times with respect to the relative seats, loading station  10  and transfer station  15  are greatly simplified, and stack  37  can be located in an easily accessible position beneath packing wheel  11 .