Abstract:
A unit for transferring groups of cigarettes has a conveyor having pockets for housing the groups and for feeding the groups in a first direction; a guide for guiding each group into a respective pocket along a path in a second direction crosswise to the first direction; and a safety device having a guide member adjacent to the conveyor and movable between a work position defining part of the path, and an emergency position remote from the path; the unit also having a spring for setting the guide member to the emergency position when a group of cigarettes transmits to the guide member a force over and above a given threshold value.

Description:
[0001]    The present invention relates to a unit for transferring articles.  
           [0002]    More specifically, the present invention relates to a unit for transferring groups of cigarettes on a cigarette packaging machine, to which the following description refers purely by way of example.  
         BACKGROUND OF THE INVENTION  
         [0003]    Cigarette packaging machines provide for forming groups of normally twenty cigarettes, and for packaging the groups in packaging material. In one packaging machine, the cigarettes are housed in bulk inside a hopper having a number of substantially vertical outlets, down which the cigarettes are fed by force of gravity on to a plate on which a group of cigarettes is formed.  
           [0004]    The machine comprises a transfer unit having a pocket conveyor for feeding the groups in a given first direction; a pusher for each outlet, to expel the groups of cigarettes from the hopper outlet in a second direction perpendicular to the first direction; and, for each outlet, a guide located between the outlet and the conveyor and aligned with the hopper outlet to guide the groups of cigarettes into a conveyor pocket along a path parallel to the second direction.  
           [0005]    The conveyor cyclically arrests a pocket at each guide, and, while the pockets are stationary, the pushers transfer respective groups of cigarettes through the respective guides from the outlets to the pockets. Once the groups are transferred from the outlets to the respective pockets, the pockets are fed forward in the first direction to transfer the groups to packaging wheels on the machine to wrap the groups in respective sheets of packaging material to form packets of cigarettes.  
           [0006]    When any one of the pushers, for any reason, fails to complete its travel, so that the group of cigarettes is located partly inside the pocket and partly inside the guide, the forward movement of the pocket in the first direction subjects the group to shearing stress, which is opposed strongly by the group of cigarettes, on account of the guide having compressed the cigarettes together, so that the group acts substantially as a single body and is resistant enough to cause failure of the weaker or less firmly connected structural elements. In the case in question, the worst damage is caused to the pocket, which breaks away from the conveyor.  
           [0007]    The above drawback is further compounded by the pocket having to be fitted back on to the conveyor, which means arresting the whole unit, and consequently the machine as a whole, for relatively long periods.  
         SUMMARY OF THE INVENTION  
         [0008]    It is an object of the present invention to provide a unit for transferring articles, designed to eliminate the above drawback of known transfer units, and which in particular need not be arrested in the event of incomplete transfer of the article.  
           [0009]    According to the present invention, there is provided a unit for transferring articles, in particular groups of cigarettes; the unit comprising a conveyor having at least one pocket for housing the articles and for feeding the articles in a first direction; and a guide for guiding the articles into a said pocket along a transfer path in a second direction crosswise to said first direction; and the unit being characterized by comprising a safety device comprising a guide member adjacent to the conveyor and movable between a work position defining part of the transfer path, and an emergency position remote from the transfer path; and a first actuator for setting the guide member to the emergency position when the articles transmit to the guide member a force over and above a threshold value. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 shows a plan view, with parts in section and parts removed for clarity, of a packaging machine comprising a transfer unit in accordance with a preferred embodiment of the present invention;  
         [0012]    [0012]FIG. 2 shows a front view, with parts in section and parts removed for clarity, of a detail of the FIG. 1 unit;  
         [0013]    FIGS.  3  to  6  show side views, with parts in section and parts removed for clarity, of a detail of the FIG. 1 unit at successive stages respectively comprising a work stage, an emergency stage, a maintenance stage, and a reset stage. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    With reference to FIGS. 1 and 2, number  1  indicates as a whole a machine for packaging cigarettes  2 , and which arranges the cigarettes in groups  3  and wraps groups  3  in respective sheets of packaging material not shown. Machine  1  comprises a frame T supporting a hopper  4  for receiving cigarettes  2  in bulk and forming groups  3 ; and a transfer unit  5  for transferring groups  3 . Hopper  4  comprises a number of outlets  6 , each of which comprises feed channels  7  for cigarettes  2 , and a bottom supporting plate  8  for arresting cigarettes  2 . The cigarettes  2  contacting plate  8  form a bottom layer  9 , on top of which are formed successive layers  9  of cigarettes; and a group  3  of cigarettes  2  comprises three superimposed layers  9 , which are subsequently compressed to compact cigarettes  2  as far as possible.  
         [0015]    Transfer unit  5  comprises a pusher  10  located at each outlet  6 ; a guide  11  located on the opposite side of outlet  6  to pusher  10 ; and a conveyor  12 , in turn comprising a number of pockets  13  fed in a direction D 1 . Pusher  10  comprises a rod  14 ; and fingers  15 , which are inserted inside the various channels  7  to expel a group  3  from outlet  6  and transfer group  3  through guide  11  into a pocket  13  arrested in front of guide  11 . Each pusher  10  is operated independently of the other pushers  10  by a respective linear actuator  16 , which moves pusher  10  back and forth in a direction D 2  perpendicular to direction D 1 .  
         [0016]    With reference to FIGS.  3  to  6 , guide  11  comprises a tubular sleeve  17  adjacent to hopper  4 ; and a guide member  18  adjacent to conveyor  12 . Tubular sleeve  17  comprises a bottom wall  19 ; a top wall  20  parallel to bottom wall  19 ; and two lateral walls  21  perpendicular to walls  19  and  20  and converging in direction D 2 , from outlet  6  towards conveyor  12 , to form a tapering channel  22  for compacting cigarettes  2  in each group  3  fed through guide  11 . Guide member  18  defines two parallel, facing lateral walls  23 , which, in use, are adjacent to walls  19  and  20  and project towards conveyor  12  with respect to lateral walls  21 .  
         [0017]    Bottom wall  19  of sleeve  17  projects with respect to lateral walls  21  towards hopper  4 , and forms a supporting surface for cigarettes  2  together with plate  8 .  
         [0018]    Transfer unit  5  comprises, for each guide  11 , a tipping device  24  connecting sleeve  17  to frame T; and a safety device  25  comprising guide member  18  of guide  11  and fitted to tipping device  24 . Unit  5  also comprises a reset device  26  common to all of guides  11 .  
         [0019]    Tipping device  24  comprises a rod  27 , which is located beneath sleeve  17  and is connected to a point along bottom wall  19  of sleeve  17  by a hinge  28  having an axis parallel to direction D 1 , and to a point on frame T by a hinge  29  also having an axis parallel to direction D 1 .  
         [0020]    Device  24  also comprises a slide  30 , which is fitted to slide along a guide  31  integral with frame T and extending in a vertical direction D 3 , and is connected to a point along bottom wall  19  of sleeve  17  by a hinge  32  having an axis parallel to direction D 1 .  
         [0021]    Device  24  also comprises an actuator  33  extending along guide  31  and having one end fixed to frame T and the other end fixed to slide  30 .  
         [0022]    In addition to guide member  18 , safety device  25  also comprises a spring  34 ; a slot  35  housing spring  34  and formed in slide  30 ; and two teeth  36  and  37  integral with slide  30  and guide member  18  respectively. With reference to FIG. 2, guide member  18  comprises a central body  38 , from which the two walls  23  project upwards, and from which projects downwards a projection  39  connected by a pin  40  to a slide  41  running in a guide  42  formed on slide  30 . Projection  39  and slide  41  are connected by pin  40 , which allows guide member  18  to oscillate about an axis  43  of pin  40  parallel to direction D 2 . Guide member  18  supports two rollers  44  and  45  located on opposite sides of slide  30  and loosely engaging respective guides  46  and  47  formed in slide  30  and which restrict the oscillation of guide member  18  to a few degrees. Each guide member  18  comprises a bottom surface  48  of central body  38 ; and an elongated slot  49  formed in central body  38  and which comes out at surface  48 .  
         [0023]    With reference to FIG. 2 and FIGS.  3  to  6 , reset device  26  comprises a linear actuator  50  having one end integral with frame T and the other end hinged to a crank  51 , which rotates with respect to frame T about an axis  52  parallel to direction D 1 , and is integral with a shaft  53  extending parallel to axis  52  at each safety device  25 . Reset device  26  comprises a number of rods  54 , each of which is located at a respective guide member  18 , is integral with shaft  53 , and rotates about axis  52  between a rest position engaging slot  49  as shown in FIG. 4, and a work position resting against surface  48  to brace guide member  18  as shown in FIG. 6.  
         [0024]    Unit  5  also comprises rubber pads  55  for cushioning the impact of guide member  18  when withdrawn by spring  34 .  
         [0025]    In actual use, and with reference to FIG. 1, groups  3  of cigarettes are transferred by pushers  10  from respective outlets  6  to pockets  13  through guide  11  along a transfer path P parallel to direction D 2 . At this stage, sleeve  17  and guide member  18  are in the work position (FIG. 3) and together define guide  11  and path P. In the event any one of pushers  10  fails to complete its travel, owing to a malfunction of respective actuator  16  or to blockage of outlet  6 , the group  3  of cigarettes may assume the position shown in the central outlet in FIG. 1, i.e. astride guide  11  and pocket  13 , so that, when conveyor  12  feeds pockets  13  in direction D 1 , group  3  reacts with a force opposing motion and exerts a force in direction D 1  on wall  23  of guide member  18 . Given the extremely small distance L 1  between walls  23  and pocket  13 , the force subjects group  3  to what is tantamount to shearing stress, is resisted strongly by group  3 , owing to the cigarettes  2  in group  3  reacting to the shearing stress, not singly, but as a body, and is transmitted by group  3  to wall  23 .  
         [0026]    With reference to FIG. 2, the force exerted on wall  23  rotates guide member  18  anticlockwise, in FIG. 2, about axis  43 ; which rotation is limited by rollers  44  and  45  engaging respective guides  46  and  47 , but is sufficient to release teeth  36  and  37  so that spring  34  withdraws guide member  18  downwards in direction D 3 . Guide member  18  is guided, by slide  41  engaging guide  42  and by rollers  44  and  45  engaging respective guides  46  and  47 , into an emergency position (FIG. 4) in which walls  23  of guide member  18  are set, with respect to transfer path P, to a remote position in which they form no part of guide  11 .  
         [0027]    With reference to FIG. 1, once guide member  18  is lowered into the emergency position beneath bottom wall  19  of sleeve  17 , walls  21  of sleeve  17  are located a distance L 2  from pocket  13  and the force exerted on group  3  is tantamount to a bending moment to which cigarettes  2  react singly by bending to allow conveyor  12  to move forward. The change in the reaction of cigarettes  2  in group  3  is due to cigarettes  2 , at this stage, having room to deform and turn inwards under the bending moment.  
         [0028]    In FIG. 3, transfer unit  5  is set to the work position, teeth  36  and  37  are mutually engaged, and rods  54  are located beneath and aligned with respective slots  49 . When teeth  36  and  37  are released by the force transmitted by a partly transferred group  3 , guide member  18  is lowered by spring  34  into the FIG. 4 emergency position in which rod  54  engages the slot  49  of the released guide member  18 , and sleeve  17  is set to the work position. At this stage, slide  41  is located at the bottom of respective guide  42 .  
         [0029]    With reference to FIG. 5, following a command from a central control unit (not shown) and determined by a sensor (not shown) for detecting the position of guide member  18 , actuator  33  of tipping device  24  is operated to move slide  30  upwards in direction D 3  and tip sleeve  17  about hinges  28  and  29  into a maintenance position. When slide  30  and sleeve  17  are set to the maintenance position, guide member  18  remains in the same position with respect to slide  30 , but changes position with respect to conveyor  12  and is set above the work position. In other words, the upward movement of slide  30  is greater than the downward movement of guide member  18  with respect to slide  30 . At this stage, actuator  50  of reset device  26  is operated to set rods  54  to the respective work positions. The rod  54  engaging slot  49  is released by the upward movement of member  18  together with slide  30 , and is rotated about axis  52  into the work position.  
         [0030]    With reference to FIG. 6, after clearing any cigarettes  2  from outlet  6  and sleeve  17 , the operator activates actuator  33  to restore sleeve  17  and guide member  18  to the work position. Actuator  33  is withdrawn and slide  30  is lowered in direction D 3  to set sleeve  17  to the work position. As it moves down, the released guide member  18  rests on rod  54 , and, as slide  30  moves down, changes position with respect to slide  30  so that tooth  37  of guide member  18  engages tooth  36  of slide  30 . Teeth  36  and  37  are allowed to engage by rod  54  being located on the same side of axis  43  as teeth  36  and  37 , so as to produce a clockwise rotation in FIG. 2 upon guide member  18  contacting rod  54 . In other words, rod  54  keeps tooth  37  in a position of interference with respect to tooth  36 . As shown in FIG. 2, teeth  36  and  37  have respective beveled ends, so that tooth  37 , on contacting tooth  36  as slide  30  moves down, produces a clockwise rotation about axis  43  in FIG. 2 to clear tooth  36 , and is then restored to the interference position by rod  54 . When slide  30  reaches the bottom limit position, tooth  37  rests on tooth  36  and is once more held against tooth  36  by spring  34 .  
         [0031]    Actuator  50  is then withdrawn and rods  54  are again positioned at respective slots  49 .  
         [0032]    The unit described has the advantage of avoiding any stoppage of the packaging machine in the event of incomplete transfer of a group, and of enabling the cigarettes clogging the guide or hopper outlet to be removed easily without stopping the machine, which continues operating to a lesser degree as the operator repairs the pusher and removes the cigarettes clogging the outlet and/or guide.