Abstract:
A method and unit continously transferring a group of cigerettes between conveyers, whereby the group of cigarettes is formed in a first seat on a group-forming first conveyor, and is fed by the first conveyor to a transfer station where the longitudinal ends of the group are engaged by a movable seat, which is moved with respect to the first seat to transfer the group from the first seat to a second seat on a wrapping conveyor.

Description:
The present invention relates to a method of transferring a group of cigarettes continuously between conveyors. 
     More specifically, the present invention relates to a method of continuously transferring a group of cigarettes from a seat on a continuous supply conveyor to a corresponding seat on a continuous wrapping conveyor or wheel. 
     Here and hereinafter, the term “group of cigarettes” is intended to mean a number of cigarettes arranged in a number of layers with no outer sheet of wrapping material, i.e. a number of cigarettes which, to remain together, need some sort of outer retaining wrapping. 
     BACKGROUND OF THE INVENTION 
     In known units for transferring a group of cigarettes from a seat on a continuous supply conveyor to a corresponding seat on a continuous wrapping wheel, as described for example in British Patent No. 1,203,259, the supply conveyor is normally defined by a chain or belt conveyor, the seats of which are fed along a path having one portion—hereinafter referred to as the “transfer portion” —which reproduces a portion of the circular path along which the seats on the wrapping wheel are fed. Along the transfer portion, the seats on the supply conveyor are moved in time, and maintained coaxial, with the corresponding seats on the wrapping wheel to transfer the group of cigarettes axially between two corresponding coaxial seats. 
     Axial transfer involves several drawbacks by subjecting the group of cigarettes to fairly severe mechanical stress (especially on modern packing machines capable of producing over ten packets a second) which may result in deformation of the cigarettes or tobacco fallout. 
     Axial transfer also requires that the supply conveyor and wrapping wheel be positioned side by side, i.e. in two different planes, which therefore increases the overall depth of the transfer unit and complicates control and maintenance. 
     Finally, the need for a common path portion defined by said transfer portion—between the wrapping wheel and the supply conveyor makes for a highly rigid arrangement of the conveyors, and calls for an extremely long and therefore bulky, high-cost chain or belt, as shown clearly by the device described in British Patent No. 1,203,259. A shorter chain or belt may be used, but only on condition that it be fed along a much more tightly curving path, thus subjecting the chain or belt to extremely severe mechanical stress. 
     EP Patent No. 548,978 discloses a unit for continuously transferring a group of cigarettes between relevant seats of two wrapping wheels. At a given transfer zone the seats on the two wheels are maintained facing and parallel to each other and to a fixed direction—in particular, a direction perpendicular to the respective axes of rotation of the wheels—by moving, in particular oscillating, the seats continuously with respect to the respective wheels. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method of continuously transferring a group of cigarettes, designed to eliminate the aforementioned drawbacks, and which in particular is straightforward and cheap to implement. 
     According to the present invention, there is provided a method of transferring a group of cigarettes continuously between conveyors, the method comprising a conveying step wherein said group is fed, by means of a first conveyor traveling continuously in a first direction, along a first path comprising an initial straight loading portion and a final transfer portion; and a transfer step wherein said group is transferred, as the group travels along said transfer portion, from said first conveyor to a second conveyor traveling continuously in a second direction along a second path; the method being characterized in that said first path and said second path are coplanar; said transfer step being performed by housing the group, at least as the group is fed along said transfer portion, inside a movable seat, which is fed by said first conveyor at least along said transfer portion, and is simultaneously moved, with respect to said first conveyor and as the movable seat travels along the transfer portion, between a first position along said first path and a second position along said second path, so as to effect a rotation of said group to enable the group to travel along said straight loading portion and said second path with two respective different orientations with respect to said first direction and said second direction respectively; said two orientations being substantially at 90° to each other. 
     The present invention also relates to a unit for transferring a group of cigarettes continuously between conveyors. 
     According to the present invention, there is provided a unit for transferring a group of cigarettes continuously between conveyors, the unit comprising a first conveyor for feeding said group continuously and in a first direction along a first path comprising an initial straight loading portion and a final transfer portion; a second conveyor for feeding said group continuously and in a second direction along a second path; and transfer means acting along said transfer portion to transfer said group from the first conveyor to the second conveyor; characterized in that said first path and said second path are coplanar; said transfer means comprising a movable seat for housing the group and which is fed by said first conveyor at least along said transfer portion; and actuating means for moving said movable seat, with respect to the first conveyor and as the movable seat is fed along said transfer portion, between a first position along said first path and a second position along said second path to effect a rotation of said group to enable the group to travel along said straight loading portion and said second path with two respective different orientations with respect to said first direction and said second direction respectively; said two orientations being substantially at 90° to each other. 
    
    
     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 front view of a first preferred embodiment of the unit according to the present invention; 
     FIG. 2 shows a schematic front view of a first detail of the FIG. 1 unit in different operating positions; 
     FIG. 3 shows a larger-scale schematic front view of a second detail of the FIG. 1 unit in different operating positions; 
     FIG. 4 shows a larger-scale view in perspective of a third detail of the FIG. 1 unit; 
     FIG. 5 shows a larger-scale schematic front view of the FIG. 1 detail in different operating positions; 
     FIG. 6 shows a schematic front view of a second embodiment of the unit according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Number  1  in FIG. 1 indicates as a whole a transfer unit forming part of a continuous automatic packing machine for producing packets of cigarettes not shown. On unit  1 , a group  2  of cigarettes is formed (in known manner not shown) inside a respective seat  3  fed continuously and a direction Di along a path Pi by an endless forming conveyor  4 , and is then transferred to a corresponding seat  5  fed continuously and in a direction D 2  along a path P 2  by an endless wrapping conveyor defined by a wrapping wheel  6 . 
     Path P 1  is coplanar with path P 2 , and comprises an initial loading portion P 3  at a loading station S 1 , and a final transfer portion P 4  at a transfer station S 2  where the group  2  of cigarettes is transferred by a seat  7  carried by a transmission pulley  8  of conveyor  4 . Seat  7  is a movable seat for receiving group  2  from seat  3  on forming conveyor  4  and feeding group  2  to the corresponding seat  5  on wrapping wheel  6 . 
     At transfer station S 2 , pulley  8  feeds each seat  7  along a path substantially coincident with transfer portion P 4  of path P 1 . 
     Group  2  is confined within a substantially parallelepiped space defined by a pair of parallel large lateral surfaces  9   a , and by a pair of parallel small lateral surfaces  9   b  perpendicular to surfaces  9   a . As shown more clearly in FIG. 4, said space also comprises two opposite longitudinal ends  9   c , and a central portion  9   d  interposed between the two longitudinal ends  9   c.    
     Along loading portion P 3  of path P 1 , group  2  is conveyed by forming conveyor  4  with a first orientation with respect to direction D 1 , and wherein small lateral surfaces  9   b  are substantially perpendicular to direction D 1 ; and along path P 2 , group  2  is conveyed by wrapping wheel  6  with a second orientation with respect to direction D 2 , and wherein large lateral surfaces  9   a  are substantially perpendicular to direction D 2 . When transferred from conveyor  4  to wheel  6 , group  2  is obviously rotated 90° about its own longitudinal axis (not shown) parallel to the cigarettes forming group  2 . 
     Before being fed through transfer station S 2 , each seat  5  is fed through a supply station (not shown) where seat  5  receives a sheet  10  of foil wrapping material, which is folded into a U inside seat  5 , and in which a respective group  2  is wrapped after being transferred to corresponding seat  5 . 
     Wrapping wheel  6  comprises a cylinder  11  powered to rotate continuously (clockwise in FIG. 1) about a central axis  12  perpendicular to the FIG. 1 plane; and a number of peripheral heads  13  (only one shown) equally spaced about axis  12 . Each head  13  defines a respective seat  5  for first receiving and conveying a respective sheet  10  of wrapping material folded substantially into a U, and for subsequently receiving and conveying a respective group  2  of cigarettes, which is wrapped in sheet  10  of wrapping material as the group is fed along path P 2 . 
     Each head  13  is hinged to cylinder  11  and is oscillated about an axis  14  parallel to axis  12  by a known cam control device  15  (shown schematically in FIG.  1 ); and seat  5  of each head  13  is defined by an end wall  16  fitted to head  13 , and by two lateral walls  17 , which are hinged to opposite ends of wall  16  and are oscillated, by a control device  19  and about respective axes  18  parallel to axis  12 , between an open and a closed position. 
     As shown in FIG. 1, control device  19  comprises a slide  19   a  supporting end wall  16  and which is moved along head  13 , in a direction perpendicular to end wall  16 , by a known cam device (not shown); and two ties  19   b , each of which is interposed between head  13  and an intermediate point along a respective lateral wall  17 , so that each axial movement of slide  19   a  with respect to head  13  rotates lateral walls  17  about respective axes  18 . 
     In the open position, the two lateral walls  17  of each seat  5  form an obtuse angle with end wall  16 , and seat  5  has a section in the form of an isosceles trapezium. In the closed position, the two lateral walls  17  of each seat  5  substantially form a right angle with end wall  16 , and seat  5  has a rectangular section of substantially the same size as group  2  so as to engage group  2  completely, i.e. at both central portion  9   d  and longitudinal ends  9   c.    
     The inner surfaces of walls  16  and  17  comprise a number of holes (not shown) connected to a known suction device (not shown) carried by wrapping wheel  6 . 
     Each head  13  also comprises a known folding device or arm  20 , which is hinged to head  13  and oscillated about axis  14  by a known cam device (not shown) to longitudinally fold a projecting portion of a sheet  10  of wrapping material folded into a U about a respective group  2  of cigarettes and housed inside seat  5 . 
     Forming conveyor  4  comprises a known flexible endless toothed belt  21  (shown partly in FIG. 1) fed along path P 1  (shown partly in FIG. 1) by pulley  8 , which comprises a toothed central roller  22  rotating continuously (anticlockwise in FIG. 1) about a central axis  23  parallel to axis  12 . 
     Loading station S 1  is shown schematically in FIG. 1 and, in a first embodiment, is substantially located at the point at which a complete group  2  of cigarettes is fed to a respective seat  3  by a known forming unit not shown. In a further embodiment, conveyor  4  is a forming conveyor for forming groups  2 , and loading station S 1  is substantially located along a portion of conveyor  4  in which a group  2  of cigarettes is formed layer by layer inside a respective seat  3  by a known hopper-type forming device (not shown) as described for example in U.S. Pat. No. 5,070,991. 
     Transfer portion P 4  of path P 1  is located at transfer station S 2  and at pulley  8 , and extends substantially along an initial portion of a curved portion of path P 1  extending about axis  23 . 
     Conveyor  4  also comprises a number of heads  24  (only one shown) carried by and equally spaced along belt  21 . As shown more clearly in FIG. 2, each head  24  defines a respective seat  3  having a longitudinal dimension (perpendicular to the FIG. 2 plane) smaller than that of group  2 , and having a rectangular section of substantially the same transverse size as group  2 , so as to engage group  2  by central portion  9   d  while leaving respective longitudinal ends  9   c  substantially free. 
     Each head  24  is connected to belt  21  in substantially fixed manner by means of two pins  25 , which cooperate with respective seats  26  on head  24  to enable head  24  to move slightly with respect to belt  21  to adjust to the curved portions of path P 1 . 
     Each head  24  has a retaining device  27  comprising two jaws  28  integral with belt  21  and which oscillate between a gripping position (as shown for example in FIG. 2 a ) along the straight portions of belt  21 , and a release position (as shown for example in FIG. 2 c ) along the curved portions (only one shown) of belt  21 . 
     In addition to roller  22 , pulley  8  comprises two flanges  29  (only one shown) coaxial with axis  23  and supporting, in between, a number of peripheral heads  30  (only one shown in FIG. 1) equally spaced about axis  23  and mounted for rotation about respective axes  31  parallel to axis  23 . 
     As shown more clearly in FIGS. 4 and 5, each head  30  has a pin  32  coaxial with axis  31  and fitted at opposite ends to two appendixes  33  of respective flanges  29 ; each head  30  comprises two gripping devices  34 , which together define a respective seat  7 ; and each gripping device  34  comprises two relatively thin L-clamps  35  located in the same plane perpendicular to axis  31 , and movable, with respect to each other and in said plane, between a release position (FIG. 5 a ) and a gripping position (FIG. 5 b ) in which clamps  35  define a tubular seat  35   a  having an axis parallel to axis  31  and a rectangular section of approximately the same size as but no larger than the cross section of a group  2 . Each gripping device  34  is fitted to a respective rocker arm  36  hinged about axis  31  by a central sleeve  37  fitted in rotary and axially-sliding manner to respective pin  32 . 
     The angular and axial position of each sleeve  37  is controlled by an actuating and control device  38 , which comprises an arm  39  projecting radially from sleeve  37  and fitted on the free end with a tappet roller  40 , which rotates about a respective axis perpendicular to axis  31  and engages a track  41  formed in a fixed cam  42  located between flanges  29  and forming part of device  38 . Track  41  extends about axis  23  to control the axial position of sleeve  37  along respective pin  32  alongside variations in the angular position of respective seat  7  about axis  23 . 
     Actuating and control device  38  also comprises, for each sleeve  37 , an arm  43  projecting radially from sleeve  37 ; and a tappet roller  44  fitted to the free end of arm  43  to rotate, about a respective axis parallel to axis  31 , along a respective track  45  formed on cam  42  and extending about axis  23  to control the angular position of sleeve  37  about axis  31  of respective pin  32  alongside variations in the angular position of respective seat  7  about axis  23 . 
     Each gripping device  34  also has an actuating device  46  comprising an articulated parallelogram  47 , which in turn comprises two parallel rods  48  hinged to rocker arm  36 , and two parallel rods  49 , each fitted at one end with a respective L-clamp  35  of gripping device  34 . One of the two rods  49 , indicated  49   a , is fitted, on the opposite end to that supporting respective clamp  35 , with a tappet roller  50  mounted for rotation, about a respective axis parallel to axis  31 , along a respective track  51  formed on cam  42  and extending about axis  23  to control the axial position of rod  49   a  with respect to respective pin  32  alongside variations in the angular position of respective seat about axis  23 . 
     Track  41  of cam  42  is so formed that, as pulley  8  rotates about axis  23 , the two rocker arms  36  of each seat  7  are moved, along axis  31  of respective pin  32 , between an open position of respective gripping device  34 —wherein the two tubular seats  35   a  are separated by a distance greater than the length of a respective group  2  of cigarettes—and a closed position of respective gripping device  34 —wherein the two tubular seats  35   a  define respective seat  7  and grip and retain a respective group  2  of cigarettes by engaging ends  9   c  of group  2 . 
     Track  45  of cam  42  is so formed that, as pulley  8  rotates about axis  23 , the two rocker arms  36  of seat  7  are rotated, about axis  31  of respective pin  32 , between a loading position—wherein seat  7  coincides with a respective seat  3  to remove a group  2  of cigarettes from seat  3 —and an unloading position—wherein seat  7  coincides with a respective seat  5  to transfer group  2  to seat  5 . 
     Track  51  of cam  42  is so formed that, as pulley  8  rotates about axis  23 , rod  49   a  is moved, with respect to respective pin  32 , to deform articulated parallelogram  47  and move clamps  35  between said gripping and release positions. 
     Operation of unit  1  will be described with reference to one group  2  of cigarettes, and as of when group  2  arrives at station S 1 . 
     Belt  21  moves continuously to feed seat  3  and respective group  2  of cigarettes along path P 1 , first along loading portion P 3  and then along transfer portion P 4  at transfer station S 2 . 
     As shown more clearly in FIG. 2, as seat  3  is fed by conveyor  4  along transfer portion P 4 , gripping devices  34  of a corresponding seat  7  are set by control devices  38  and  46  to said open and release positions (FIG. 2 a ). Control device  38  then swings seat  7  about respective axis  31  to assume and maintain for a given length of time a position substantially coincident with seat  3  (FIG. 2 b ) and wherein control devices  38  and  46  set gripping devices  34  of seat  7  to said closed and gripping positions to grip group  2 . At the same time, the curvature of transfer portion P 4  moves retaining device  27  of seat  3  into said release position to leave group  2  under the control of seat  7  (FIG. 2 c ). 
     At this point, seat  7  is rotated about respective axis  31  to extract group  2  from seat  3  (FIG. 2 d ) and feed the group towards a corresponding seat  5 , which, as wrapping wheel  6  rotates continuously, is being fed through transfer station S 2  (FIG. 1) with lateral walls  17  in said open position, and with a U-folded sheet  10  of wrapping material housed and retained inside by said suction device (not shown). 
     As shown more clearly in FIG. 3, in the neighbourhood of transfer station S 2 , seat  7  and corresponding seat  5  are swung about respective axes  31  and  14  by respective control devices  38  and  15  to assume and maintain for a given length of time a substantially mutually coincident position (FIG. 3 a ), whereupon control device  19  moves lateral walls  17  of seat  5  into said closed position to grip group  2  and at the same time finish-fold sheet  10  of wrapping material into a U about group  2  (FIG. 3 b ). 
     In the FIG. 3 b  position, seat  5 , with sheet  10  of wrapping material in between, engages both group  2  and clamps  35  of gripping devices  34  of seat  7 , which is made possible by the thinness of clamps  35 . 
     Once group  2  is gripped by seat  5 , control device  38  moves gripping devices  34  of seat  7  into said open position, so that clamps  35 , though still in said gripping position, are withdrawn longitudinally with respect to group  2  to release group  2 . 
     At this point, seats  5  and  7  move out of said mutually coincident position, and control device  38  restores seat  7  to the initial position. At the same time, folding device  20  of seat  5  is activated to longitudinally fold sheet  10  of wrapping material about group  2 , and wrapping wheel  6  rotates continuously to fed seat  5  through successive known folding stations (not shown). 
     In a further embodiment not shown, seats  7  are carried by forming conveyor  4  itself, and each seat  3  is assigned a respective seat  7  fitted to conveyor  4  and adjacent to seat  3 . 
     In a further embodiment shown in FIG. 6, seats  3  on forming conveyor  4  are as described in European Patent Application No. 812,765, and each engage the longitudinal ends of a respective group  2  of cigarettes; seats  3  are carried by respective forks  52  fitted to belt  21  so as to rotate about respective axes  31  parallel to axis  23  of pulley  8 ; and, along transfer portion P 4 , a known cam control device (not shown) rotates each seat  3  about respective axis  31  to transfer respective group  2  to a corresponding seat  5  in exactly the same way as described for seats  7 .