Abstract:
A method and device for conveying folded sheet elements, whereby a sheet element, folded to have at least two superimposed portions connected along a fold, is fed along a given path by a movable gripping head, which engages and retains by suction a first of the two portions of the sheet element, and simultaneously deforms the fold to retain the second portion in contact with the first as the sheet element is conveyed.

Description:
The present invention relates to a method of conveying folded sheet elements. 
   The present invention may be used to advantage in the tobacco industry to supply a line for packing tobacco products, in particular cigarettes, with sheet elements defined by folded coupons, to which the following description refers purely by way of example. 
   BACKGROUND OF THE INVENTION 
   On some packing lines in the tobacco industry, each packet of cigarettes produced or being produced on the line is provided with a coupon, which at times is folded to form at least two superimposed portions connected along a fold. 
   Single-sheet coupons, i.e. defined by a nonfolded sheet element, are normally supplied to a packing line by means of a conveying member, which retains the coupons by suction and feeds them on to the line successively. 
   When dealing with folded coupons, however, such a conveying method, though cheap and easy to implement, poses several drawbacks, by the conveying member only engaging one of the folded portions of the coupon by suction, while the other/s, not being position controlled in any way, are allowed to “flap” freely and detach from the portion retained by suction. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a conveying method enabling even folded sheet elements to be conveyed safety by suction. 
   According to the present invention, there is provided a method of conveying sheet elements folded to comprise at least two superimposed portions connected along a fold; the method comprising the steps of engaging a first of said two portions of said sheet element by means of suction conveying means; deforming said first portion and said fold to retain a second of said portions in contact with said first portion; retaining said sheet element with said first portion and said fold deformed, and with said first portion in contact with the suction conveying means; and moving said suction conveying means along a given path. 
   The present invention also relates to a device for conveying folded sheet elements. 
   According to the present invention, there is provided a device for conveying sheet elements folded to comprise at least two superimposed portions connected along a fold; the device comprising movable conveying means having a suction surface for engaging a first of the two said portions; said suction surface retaining said first portion by suction, and being designed to simultaneously deform said fold to retain a second of said portions in contact with said first portion. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described with reference to the accompanying drawings, in which: 
       FIG. 1  shows a schematic, three-quarter underside view in perspective of a preferred non-limiting embodiment; 
       FIG. 2  shows a view in perspective of a second embodiment of a detail in FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Number  1  in  FIG. 1  indicates as a whole a device for conveying and feeding a coupon  2  to a known cigarette packing line  3 . 
   In the example shown, coupon  2  is fan-folded, and comprises a first pair  4  of superimposed portions  5  and  6  connected to each other along a fold  7 ; and a second pair  8  of superimposed portions  9  and  10  connected to each other along a fold  11  parallel to fold  7 . Portions  6  and  9  are also connected to each other along a fold  12  parallel to and opposite folds  7  and  11 . 
   Device  1  comprises a transfer unit  13 , in turn comprising a slide  14  powered in known manner (not shown) to run back and forth, along a guide  15  and in a direction  15   a  which, in the example shown, is substantially horizontal, between a pickup station  16 , to pick up a coupon  2 , and a feed station  17 , to feed coupon  2  to packing line  3 . Transfer unit  13  also comprises a telescopic actuator  18  suspended from slide  14  and fitted on its bottom free end with a gripping head  19 , which is defined at the bottom by a suction surface  20  facing a gripping position  21  of pickup station  16 , and is moved by actuator  18  to and from gripping position  21  in a direction  22  which, in the example shown, is substantially vertical. 
   Surface  20  is a cylindrical curved surface (concave in the example shown) with generating lines parallel to direction  15   a , and faces a cylindrical curved surface  23  (concave in the example shown), complementary to surface  20  and with generating lines parallel to direction  15   a , of an anvil  24 , which is located on the opposite side of pickup station  16  with respect to transfer unit  13 , and is moved to and from gripping position  21  in direction  22  by a telescopic actuator  25  which is substantially coaxial with actuator  18  when transfer unit  13  is at pickup station  16 . 
   In a variation not shown, anvil  24  has an actuator  25 , and is fixed at gripping position  21 . 
   Device  1  also comprises a guide  26  extending, parallel to direction  15   a , between pickup station  16  and feed station  17 , and which is coplanar with gripping position  21  and comprises two channel sections  27  positioned with their concavities facing each other, and separated by a distance substantially equal to the length of folds  7 ,  11  and  12 . 
   Finally, device  1  comprises a feed device  28  for feeding coupons  2  to pickup station  16 . In the example shown, device  28  is a known gripper-type feed device, which moves to and from pickup station  16  in a direction  29  perpendicular to directions  15   a  and  22 , to feed each coupon  2  to gripping position  21  with folds  7 ,  11  and  12  extending crosswise to the generating lines of surfaces  20  and  23 . 
   In actual use, when a coupon  2 , positioned with folds  7 ,  11  and  12  parallel to direction  29 , is fed by feed device  28  to gripping position  21 , transfer unit  13  is located at pickup station  16 , and gripping head  19  and anvil  24  are raised and lowered respectively with respect to gripping position  21 . Gripping head  19  and anvil  24  are then moved towards each other to grip coupon  2  between surfaces  20  and  23 , which, cooperating with each other, curve folds  7 ,  11  and  12 , which are “frozen” in this curved position by activating suction through surface  20 . The suction, in fact, by acting directly on at least portion  5  and fold  7  of coupon  2 , itself keeps these two elements in the curved position even without anvil  24 . Maintaining a curved fold  7  also keeps portion  6  and fold  12  curved, so that portions  9  and  10  and fold  11  are also maintained curved and so adhere to portions  5  and  6  even without anvil  24 . 
   At this point, anvil  24  can be lowered and the slide moved in direction  15   a  to feed coupon  2  along guide  26  to feed station  17 . In the course of this movement, any lateral portions of coupon  2  projecting crosswise to direction  15   a  from gripping head  19  engage the inside of respective sections  27 , which may even be dispensed with and serve solely to prevent coupons  2  from dropping in the event suction is cut off, and possibly also to center coupons  2  with respect to gripping head  19 . 
   As will be clear from the foregoing description, to engage a folded sheet element by suction along at least one fold and convey the sheet element, without flapping, along a given path, the fold must be maintained curved as the element is conveyed. And when dealing with multiple parallel folds, as in the example shown, all the folds must obviously be maintained curved as the element is conveyed. 
   Though, in the example shown, surface  20  is concave and surface  23  convex, the same result would obviously be achieved even with a convex surface  20  and a concave surface  23 . Surface  20  may also have any shaped curve, or even be undulated. 
   In the  FIG. 2  example, surface  20  of gripping head  19 , when sectioned crosswise to direction  15   a , is substantially V-shaped and defined by two flat portions  20 ″ and  20 ″′ connected by a rib  20 ′. 
   As will be clear from the foregoing description, once folds  7 ,  11  and  12  are all curved by the opposite pressures exerted by gripping head  19  and anvil  24 , the suction through surface  20 , by acting directly on portion  5  and fold  7 , is sufficient to keep all folds  7 ,  11  and  12  curved, so that portions  5 ,  6 ,  9  and  10  all adhere to one another and to surface  20 . When dealing with a coupon only comprising portions  5  and  6  and fold  7 , however, gripping head  19  is obviously perfectly capable of curving portion  5  and fold  7 , and therefore also portion  6 , by suction alone. Consequently, to convey by suction a sheet element simply folded into two along one fold, anvil  24  may be dispensed with or replaced, if necessary, by a straightforward fixed flat supporting plate defining gripping position  21 . 
   The same also applies when conveying by suction a sheet element folded into four along two parallel, superimposed first folds and a further intermediate fold crosswise to the other two. In which case, the intermediate fold need simply be curved directly by suction, so that all the portions of the sheet element adhere to the portion of the sheet element contacting gripping head  19  and subjected to suction. 
   To convey a sheet element folded along three or more folds forming an angle, surfaces  20  and  23  must be complementary and have, as opposed to a single curve as in the example shown, a double curve so as to curve all the folds in the sheet element to be conveyed.