Patent Publication Number: US-6991422-B2

Title: Method and unit for transferring blanks

Description:
The present invention relates to a method of transferring blanks. 
   More specifically, the present invention relates to a method of transferring blanks on an automatic packing machine for producing rigid packets of cigarettes, to which the following description refers purely by way of example. 
   BACKGROUND OF THE INVENTION 
   To produce rigid packets of cigarettes, cardboard blanks must be fed to a pickup station of the packing machine so that each blank is withdrawn individually and folded about a group of cigarettes to form a packet of cigarettes. 
   The blanks are flat pieces of cardboard cut and notched beforehand to form fold lines, and are supplied in packages comprising a pallet on which the blanks are arranged for optimum transport and packing. 
   The blanks in each package are divided into side by side stacks to form layers, which in turn are stacked on the pallet and separated from one another by separators. The cigarette packing machine comprises a blank store for supplying the pickup station, where each blank is withdrawn individually by a gripping member and transferred to folding stations on the packing machine. In the store, the blanks are arranged in a seamless succession, and are packed and aligned with one another so as to be picked up by the gripping member in a given position and with a given orientation. 
   Given the increasingly fast output rate of automatic packing machines, all the blanks in the package must be transferred rapidly to the store to replace the empty pallet with a new package and, at the same time, arrange the blanks in the required orderly succession in the store. 
   Current transfer methods fail to provide for transferring and simultaneously arranging the blanks in the required orderly succession in the store, in such a manner as to meet the requirements of modern automatic packing machines. 
   U.S. Pat. No. 5,183,380 discloses a feeding apparatus for automatically transferring stacks of blanks from a pallet to a blank magazine of a high performance packaging machine. The feeding apparatus comprises an endless pocket conveyor between a feed station and the blank magazine; each pocket of the pocket conveyor receives a relevant blank stack in the feed station, transports the blank stack along a feeding path to the supply magazine, in which the stack is automatically pushed out of the conveyor pocket into the blank magazine. The feeding apparatus disclosed by U.S. Pat. No. 5,183,380 has a relatively high fast output rate; however, such feeding apparatus is cumbersome, complicated and expensive. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a method of transferring blanks, designed to eliminate the drawbacks of known methods. 
   According to the present invention, there is provided a method of transferring blanks, on a packing machine, from a platform supporting a number of blanks divided into stacks, to a store where the blanks are packed successively and seamlessly along a first supply path of a pickup station of the packing machine; the method being characterized by forming, at a loading station and by means of at least one gripping device, a group of blanks defined by at least two stacks superimposed and aligned in a container; feeding the container along a second path to an unloading station at the store; and transferring the group of blanks from the container to the store. 
   The above method provides for packing the stacks of blanks at the loading station and then transferring a group of packed blanks directly to the store. 
   Separating pickup of the blanks and transfer of the group provides for selecting, on the one hand, the most suitable gripping device for picking up the stacks on the platform, and, on the other, the most suitable container for forming the group and transferring the group to the store. Moreover, the container so accumulates the blanks as to enable supply of the platform. 
   The present invention also relates to a unit for transferring blanks. 
   According to the present invention, there is provided a transfer unit for transferring blanks on a packing machine comprising a blank store; the transfer unit comprising a platform for supporting a number of blanks divided into stacks, and at least one transfer device for transferring said stacks of blanks from the platform to the store, wherein the blanks are packed successively and seamlessly and aligned along a first supply path of a pickup station of the packing machine; and the transfer unit being characterized by comprising a container for housing a group of blanks defined by at least two aligned and superimposed stacks, and which is movable along a second path between a loading station at said gripping device and an unloading station at said store. 
   The present invention also relates to a packing machine store designed to cooperate with the transfer unit according to the present invention. 
   According to the present invention, there is provided a blank store forming part of a machine and cooperating with a transfer unit for transferring blanks; characterized by comprising a push device having a supporting wall perpendicular to a first path and movable along said first path to support the blanks in said store. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
       FIG. 1  shows a schematic side view, with parts removed for clarity, of a packing machine with a transfer unit, and which shows a carriage-mounted container in various work positions separated by break lines; 
       FIG. 2  shows a schematic plan view of various component parts of the  FIG. 1  machine; 
       FIGS. 3 and 4  show larger-scale side views, with parts removed for clarity, of the  FIG. 1  carriage in two different work positions; 
       FIGS. 5 and 6  show side views, with parts in section and parts removed for clarity, of a detail of the  FIG. 3  carriage in two different work positions; 
       FIGS. 7   a ,  7   b ,  7   c  show plan views, with parts in section and parts removed for clarity, of a  FIG. 1  machine device in different operating positions; 
       FIG. 8  shows a larger-scale plan view, with parts in section and parts removed for clarity, of a detail of the  FIG. 7   c  device; 
       FIG. 9  shows a section along line IX—IX of the  FIG. 7   c  device; 
       FIG. 10  shows a section of  FIG. 7   c  along line X—X; 
       FIG. 11  shows a section of  FIG. 2  along line XI—XI; 
       FIG. 12  shows a larger-scale side view, with parts removed for clarity, of a device on the  FIG. 1  machine; 
       FIG. 13  shows a larger-scale side view, with parts removed for clarity, of a device on the  FIG. 1  machine; 
       FIG. 14  shows a section of  FIG. 13  along line XIV—XIV; 
       FIG. 15  shows a section of  FIG. 13  along line XV—XV; 
       FIG. 16  shows a plan view, with parts removed for clarity, of a portion of the  FIG. 1  machine; 
       FIG. 17  shows a front view, with parts in section and parts removed for clarity, of the  FIG. 16  machine portion; 
       FIG. 18  shows a section, with parts removed for clarity, of the  FIG. 16  machine portion along line XVIII—XVIII; 
       FIG. 19  shows a section, with parts removed for clarity, of the  FIG. 17  machine portion along line XIX—XIX. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1 , number  1  indicates as a whole a packing machine for producing rigid packets of cigarettes (not shown), each comprising a rigid cardboard blank  2  folded about a group of cigarettes (not shown). Blanks  2  are flat pieces of cardboard cut and notched beforehand to form fold lines (not shown), and are supplied in packages  3 , one of which is shown in  FIG. 1  and comprises a pallet  4  on which blanks  2  are arranged in orderly fashion. 
   That is, blanks  2  are arranged in side by side stacks  5  to form layers  6 , which in turn are stacked on pallet  4  and separated from one another by separators  7 . Stacks  5  rest on separators  7  or, in the case of the bottom layer  6 , directly on pallet  4 , and are unbound, i.e. have no bands or other wrappers, to simplify supply of blanks  2  to machine  1 ; and each blank  2  extends parallel to a horizontal plane perpendicular to the  FIG. 1  plane. 
   Machine  1  comprises a frame  8  supporting a gripping member  9  for withdrawing one blank  2  at a time; a store  10  for storing blanks  2  and feeding blanks  2  along a path P 1  to gripping member  9 ; and a transfer unit  11  for transferring stacks  5  of blanks from pallet  4  to store  10 . 
   Transfer unit  11  comprises a container  12  movable along a given path P 2  to transfer groups  13  of stacks  5 ; two gripping devices  14  and  15  for transferring stacks  5  of blanks; and a locating platform  16  for setting pallet  4  in a given position with respect to gripping device  14 . 
   Gripping member  9  comprises a suction-type gripping head for withdrawing a blank  2  extending parallel to a vertical plane at a pickup station S 1 , and for feeding blank  2  to folding stations (not shown) of machine  1 . 
   Store  10  comprises a conveyor  17  supporting a number of blanks  2  arranged in orderly fashion to assist withdrawal of each blank  2  by gripping member  9 . In the orderly arrangement in store  10 , blanks  2  are arranged successively, are packed and aligned with one another, extend parallel to said vertical plane, and rest on edge on conveyor  17 , which extends a given length in a horizontal direction D 1  from pickup station S 1  to form a stock of blanks  2  for supply to pickup station S 1 . 
   Conveyor  17  comprises two spaced, parallel belts  18  looped about pulleys and which support blanks  2  resting on edge on the conveying branches of belts  18 . Store  10  comprises an output gate  19 ; and a push device  20  for keeping blanks  2  in store  10  in the on-edge position. Gate  19  comprises a central opening (not shown), is located at pickup station S 1 , and provides for supporting the succession of blanks  2  and, at the same time, enabling gripping member  9  to penetrate output gate  19  to withdraw the blank  2  contacting gate  19 . 
   As shown clearly in  FIG. 2 , push device  20  provides for supporting the succession of blanks  2  on the opposite side to gate  19 , and for accompanying blanks  2  as they travel towards gate  19 . That is, gate  19  and push device  20  directly support the end blanks  2  in the succession of blanks  2  in store  10 , and indirectly support the blanks  2  between the two end blanks  2 . 
   Push device  20  comprises a sleeve  22 , which is movable in direction D 1  along a guide  21  parallel to conveyor  17 , and is connected to a worm  23  activated by a motor  24 . Push device  20  also comprises a supporting wall  25  perpendicular to direction D 1  and connected to sleeve  22  by an articulated quadrilateral  26 , which comprises a spring  27  extending between two opposite articulations of quadrilateral  26 , and a sensor  28  for detecting deformation of spring  27 . Sensor  28  is connected to a control unit  29  for operating motor  24 , which sets sleeve  22 , and therefore wall  25 , to such a position as produce constant deformation of spring  27 . That is, the position of wall  25  is determined by feedback control as a function of the expansion or contraction of spring  27  with respect to a set deformation value corresponding to a given pressure exerted by wall  25  on blanks  2  in store  10 . 
   Wall  25  is connected to articulated quadrilateral  26  by means of a hinge  30 , which has an axis parallel to direction D 1  and is controlled by an actuator  31  to move wall  25  between a work position (shown by the continuous line in  FIG. 11 ) in which wall  25  is located along path P 1 , and a rest position (shown by the dash line in  FIG. 11 ) in which wall  25  is located to the side of path P 1 . 
   With reference to  FIG. 1 , container  12  is mounted on a carriage  32  movable along a guide  33 , which is integral with frame  8  and comprises a straight portion  34  parallel to direction D 1  and extending partly beneath conveyor  17 , a straight portion  35  parallel to a vertical direction D 2 , and a curved portion  36  connecting the two straight portions  34  and  35 . Guide  33  is defined by two parallel rails  37 , each having an outer rolling track and an inner rolling track, as shown in  FIGS. 16 and 17 . Guide  33  defines path P 2 , which comprises a straight portion parallel to direction D 1 , and a straight portion parallel to direction D 2 ; and paths P 1  and P 2  are superimposed along a portion T substantially defining an unloading station S 2 , as described later on. 
   With reference to  FIGS. 3 and 4 , container  12  comprises a bottom wall  38 , a front wall  39 , and a rear wall  40 . Bottom wall  38  is integral with carriage  32 , which comprises a frame  41 ; front wheels  42  arranged in pairs ( FIGS. 1 ,  16 ,  17 ,  18 ) to grip the outer tracks and inner tracks of rails  37 ; and rear wheels  43  resting on the outer tracks of rails  37  ( FIG. 1 ). 
   With reference to  FIGS. 3 and 4 , front wall  39  is perpendicular to bottom wall  38  and is movable between the  FIG. 3  position and the  FIG. 4  position by means of a mechanism comprising an articulated quadrilateral, and a gear  44  and rack  45  coupling for adjusting the position of the articulated quadrilateral. The articulated quadrilateral is defined by wall  39 , by frame  41 , and by two levers  46  and  47 ; and gear  44  is connected to lever  47  by a connecting rod  48  to rotate lever  47  and set wall  39  to the  FIG. 3  or  FIG. 4  position. 
   As shown in  FIG. 19 , rack  45  is housed in a seat on frame  41  of carriage  32 , and is movable, with respect to frame  41 , parallel to path P 2  of carriage  32 . 
   With reference to  FIGS. 5 and 6 , rear wall  40  is perpendicular to bottom wall  38  and is fitted to an arm  49  connected in sliding manner to frame  41  and movable between the  FIG. 5  position and the  FIG. 6  position. The end of arm  49  opposite the end connected to wall  40  is anchored to frame  41  by a spring  50 . 
   With reference to  FIG. 1 , carriage  32  is moved along path P 2  by a chain  51 , which is looped about two transmission pulleys  52  and a drive pulley  53 , and comprises a work branch parallel to guide  33 . At curved portion  36  of guide  33 , chain  51  is guided by a curved track  54 . 
   Carriage  32  is connected to chain  51 , as shown clearly in  FIG. 19 , and is positioned by chain  51  at unloading station S 2  ( FIG. 1 ) at store  10 , and at a loading station S 3  ( FIG. 1 ) along the straight vertical portion  35  of guide  33 . Machine  1  comprises a further chain  55 , which is parallel to chain  51 , is looped about two transmission pulleys (not shown) coaxial with transmission pulleys  52 , and about a drive pulley (not shown) coaxial and integral with pulley  53 , and is guided by curved track  54 . Unlike chain  51 , chain  55  is anchored, not to carriage  32 , but to rack  45  ( FIG. 19 ), which slides with respect to frame  41  of carriage  32  to activate front wall  39 . Chain  55  is connected to a shift device  56  for varying the position of chain  55  with respect to chain  51 . 
   As shown clearly in  FIGS. 12 and 13 , shift device  56  comprises two rollers  57  located outside the loop formed by chain  55  and along the work branch of chain  55 ; two rollers  58  located outside the loop formed by chain  55  and along the return branch of chain  55 ; and two movable rollers  59  and  60  activated by an actuator (not shown) and located inside the loop formed by chain  55 . Rollers  59  and  60  can be positioned selectively between rollers  57  and  58  respectively, to vary the length of the portions of chain  55  along the work and return branches of chain  55 , and so move rack  45  with respect to carriage  32 , and wall  39  between the work positions shown in  FIGS. 3 and 4 . 
   With reference to  FIG. 2 , platform  16  has locators  61  for positioning pallet  4  with respect to platform  16 , and is movable in direction D 2  by means of a lifting device  62  shown schematically in  FIG. 1 . 
   With reference to  FIG. 1 , frame  8  supports gripping device  14  at platform  16 , and gripping device  15  at loading station S 3  for loading container  12 . Device  14  comprises an articulated arm  63  pivoting about vertical axes; and a gripper  64  in turn comprising a blade  65  and a jaw  66  located over blade  65 , which is movable substantially in a horizontal plane PA indicated by the dot-and-dash line in  FIG. 1 , and is inserted between a separator  7  and the bottom blank  2  in each stack  5 . 
   Once blade  65  is inserted beneath a stack  5 , jaw  66  is closed onto the stack  5  to withdraw it from package  3  and transfer it to gripping device  15 . Gripping device  14  provides for adjusting the position of gripper  64  with respect to plane PA in direction D 2 , but has substantially no movement in direction D 2 . 
   With reference to  FIG. 2 , gripping device  15  comprises a shaft  67  rotating about a vertical axis, and a transfer member  68  fitted to shaft  67 . Like gripping device  14 , transfer member  68  of gripping device  15  has substantially no movement in direction D 2 . As shown clearly in  FIGS. 7   a  to  7   c , transfer member  68  comprises an end wall  69  fitted to telescopic arms  70  extending radially with respect to shaft  67 ; and two lateral walls  71 , which are connected by a plate  72 , pivot with respect to plate  72  about respective vertical axes  73 , and are fitted to telescopic arms  74  parallel to telescopic arms  70  and for moving lateral walls  71  with respect to end wall  69 . 
   With reference to  FIGS. 8 ,  9  and  10 , each lateral wall  71  is L-shaped to define a bottom portion for supporting each stack  5 , and is connected to an arm  75 . Each arm  75  has one end integral with lateral wall  71  and rotating about axis  73 , and one end connected to a spring  76  located between arm  75  and plate  72 . Spring  76  is equipped with a sensor  77  for detecting deformation of spring  76  and so determining the angular position of respective wall  71 ; and sensor  77  is connected to control unit  29 , which determines deformation of springs  76  and accordingly controls displacement of gripping device  15 . 
   With reference to  FIG. 1 , transfer unit  11  also comprises a guide wall opposite the vertical portion of path P 2 ; a stop member  79  controlled by an actuator  80  and movable between a rest position and a work position intercepting wall  40  of container  12  as shown in  FIG. 14 ; and a sensor SL for detecting the level of the top layer  6  of a package  3  on platform  16 . 
   In actual use, store  10  and transfer unit  11  are controlled by control unit  29  shown schematically in  FIG. 2 . 
   A package  3  of blanks is placed on platform  16  in the position defined by locators  61 , and lifting device  62  positions package  3  so that the top separator  7  coincides with plane PA, which is determined by the position of sensor SL, and the top layer  6  of package  3  ideally rests on plane PA. Gripping device  14  takes one stack  5  at a time off the top layer  6  by means of gripper  64 , and transfers each stack  5  to gripping device  15 . When the whole layer  6  has been removed from package  3  by gripping device  14 , separator  7  is removed and platform  16  is raised to move the next separator up to plane PA and sensor SL. 
   With reference to  FIG. 2 , gripping device  15  rotates shaft  67  about its vertical axis to set transfer member  68  selectively to a receiving position shown partly by the dash line in  FIG. 2 , to a transfer position shown by the continuous line in  FIG. 2 , and to a reject position indicated as a whole by E. In the receiving position, gripper  64  inserts a stack  5  between walls  71  and onto end wall  69  of transfer member  68 . 
   The respective bottom portions of L-shaped lateral walls  71  provide for supporting stack  5 , are coincident with plane PA, and are spaced apart; and, when transferring stack  5  from gripper  64  to transfer member  68 , blade  65  is inserted between the bottom portions of lateral walls  71 . 
   In the event stack  5  or even only one of blanks  2  in stack  5  is not aligned with gripper  64 , lateral walls  71  flex by being mounted elastically. When gripper  64  releases stack  5 , lateral walls  71  exert pressure on the misaligned stack  5  or blank  2  to position stack  5  correctly inside transfer member  68  and align any misaligned blanks  2  with the other blanks  2  in stack  5  by means of springs  76 , which position walls  71  parallel and aligned with each other. 
   In the event walls  71  fail, under the action of springs  76 , to position stack  5  or blanks  2  correctly with respect to transfer member  68 , sensors  77  detect persistent deformation of springs  76  with respect to an optimum or threshold value, and control unit  29  sets transfer member  68  to reject position E to expel stack  5  by extending arms  70  to move end wall  69  forward. 
   Conversely, if the signal received by control unit  29  indicates no persistent deformation of springs  76  with respect to the optimum or threshold value, transfer member  68  is moved into the transfer position to transfer stack  5  to container  12 . In other words, lateral walls  71  define a reference system for the blanks in each stack  5  transferred to transfer member  68 , and at the same time provide for correcting the position of the blanks with respect to lateral walls  71  themselves. 
   Container  12  is moved into loading station S 3  by means of carriage  32  activated by chain  51  and drive pulley  53 . At loading station S 3 , bottom wall  38  of the carriage is perpendicular to direction D 1 ; walls  39  and  40  are perpendicular to direction D 2 ; and the empty container  12  is positioned so that wall  39  is practically coincident with plane PA. At this stage, and with reference to  FIGS. 7   a  to  7   c , gripping device  15  places a stack  5  on wall  39  by means of transfer member  68 , which, by simultaneously extending arms  70  and  74 , is moved from the transfer position ( FIG. 7   c ) into the  FIG. 7   b  position in which the bottom portions of lateral walls  71  substantially contact wall  39 . Lateral walls  71  are then withdrawn by means of arms  74 , while end wall  69  remains fixed. Following this operation, by which a stack  5  now rests on wall  39 , carriage  32  is lowered one step equal to the height of each stack  5  to place the next stack  5  on top of stack  5 . 
   Stacks  5  are placed one on top of the other inside container  12  until the top stack  5  nears wall  40 . As container  12  is lowered one step further, wall  40  contacts stop member  79 , which, in the meantime, has been set to the work position by actuator  80  and, at each step of carriage  32 , moves wall  40  away from wall  39  and the superimposed stacks  5  to enable further stacks  5  to be placed one on top of the other to form a group  13  of blanks comprising a given N number of superimposed, aligned stacks  5 . 
   In other words, at each step of carriage  32 , carriage  32  positions container  12  at loading station S 3  so that a supporting surface of container  12  is perpendicular to direction D 2  and substantially aligned with plane PA. The supporting surface is defined by front wall  39  when container  12  is empty, and by the top blank  2  in container  12  when container  12  is partly filled. 
   The blanks  2  resting on the platform and on carriage  32  at loading station S 3  extend perpendicularly to direction D 2 , while the blanks  2  housed in store  10  and container  12  at unloading station S 2  extend perpendicularly to direction D 1 . 
   Once group  13  of blanks is completed, actuator  80  resets stop member  79  to the rest position, and wall  40  is positioned contacting the top blank  2  in group  13  by means of spring  50  ( FIGS. 5 and 6 ), so as to grip group  13  between walls  39  and  40  and prevent any movement of blanks  2  as they are transferred along path P 2  from loading station S 3  to unloading station S 2 . 
   Carriage  32  and container  12  are fed along path P 2  and oriented so that bottom wall  38  of container  12  is parallel to direction D 1 , and blanks  2  are parallel to the blanks  2  in store  10 , i.e. perpendicular to direction D 1 . Group  13  of blanks is transferred from container  12  to conveyor  17  along portion T. 
   Frame  41  of carriage  32  is so formed as to penetrate between belts  18  of conveyor  17  and superimpose paths P 1  and P 2 . Carriage  32  is arrested upon container  12  contacting wall  25 , which is moved by container  12  in direction D 1 . The movement of wall  25  is detected by sensor  28 , which detects deformation of quadrilateral  26  and spring  27 . As a result, control unit  29  successively stops chain  51 , rotates wall  25  about hinge  30  into the rest position, and moves wall  25  in direction D 1  into a position aligned with rear wall  40  of container  12 . Wall  25  is then moved back into the work position shown by the continuous line in  FIG. 11 , and is moved up to group  13  without interfering with wall  40 , by virtue of the complementary shape of walls  25  and  40 . 
   As wall  25  is performing the above movements, wall  39  is lowered into the  FIG. 4  position as described previously, and carriage  32  and container  12  are sent back to loading station S 3  to receive another group  13  of blanks. On the way from unloading station S 2  to loading station S 3 , wall  39  is restored to the  FIG. 3  position as described previously. With wall  25  positioned downstream from group  13 , the transfer of container  12  from unloading station S 2  to loading station S 3  transfers group  13  of blanks from wall  38  of container  12  onto belts  18  of conveyor  17 , so that group  13  is packed directly with the blanks  2  already in store  10 . 
   A layer  6  of stacks is defined by an M number of side by side stacks, while each group is defined by an N number of superimposed stacks; and the relation between M and N may conveniently be selected so that M is a whole multiple of N, and so that a separator  7  can be removed and an empty pallet  4  replaced with a new package  3  as carriage  32  travels both ways between loading station S 3  and unloading station S 2 .