Method and device for feeding sheets to a wrapping line

Abstract: A method and device (1) for feeding sheets (2) to a wrapping line (3), whereby a suction pickup roller (8) is rolled along a bottom opening (6) of a hopper (4) containing a stack (5) of sheets, to at least partly wind about the pickup roller (8) a sheet (2), in the stack (5), located at the bottom opening (6) of the hopper (4), and is then rotated about a respective central axis (9) to release the sheet (2) wound about the pickup roller to an intermediate roller (11).

Description: The present invention relates to a method of feeding sheets to a wrapping line. The present invention may be used to advantage for feeding sheets to a wrapping line of a cigarette packing machine, to which the following description refers purely by way of example. Cigarette packing machines are known to employ a device for feeding sheets to a wrapping line as described in US Patent no. 4,918,908, whereby a suction pickup roller is rolled over and winds up a sheet located at the bottom opening of a hopper containing a stack of sheets. Once the sheet is wound fully, the pickup roller is arrested in a release position to release the sheet to an input conveyor of a wrapping line, which input conveyor is normally defined by two pickup rollers parallel and tangent to each other to engage the sheet in between. CH Patent no. 288,604 discloses a device for feeding sheets to a working line, whereby a suction pickup roller is rolled over and winds up a sheet located at the bottom opening of a hopper containing a stack of sheets; during the rolling of the suction pickup roller, the sheet partially wound up by the suction pickup roller is fed to a subsequent conveyor. US Patent no. 3,127,167 discloses a device for feeding sheets to a working line whereby a suction pickup roller is rolled over and winds up a sheet located at the upper opening of a hopper containing a stack of sheets. Once the sheet is wound around the suction pickup roller, such sheet is fed from the suction pickup roller to the working line. Though satisfactory at relatively low operating speeds, feed devices of the above type tend to severely stress and damage the sheets at relatively high operating speeds typical of modern packing machines, and particularly when releasing the sheets from the pickup roller to the input conveyor of the wrapping line. It is an object of the present invention to provide a method of feeding sheets to a wrapping line, designed to eliminate the aforementioned drawbacks, and which is also straightforward and cheap to implement. According to the present invention, there is provided a method of feeding sheets to a wrapping line as recited by Claim 1. The present invention also relates to a device for feeding sheets to a wrapping line. According to the present invention, there is provided a device for feeding a sheet to a wrapping line as recited by Claim 10. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figures 1, 2 and 3 show schematic side views, with parts removed for clarity, of three different successive instants in the operation of a preferred embodiment of the feed device according to the present invention; Figure 4 shows a schematic view of five different successive instants in the operation of a detail in Figure 1. Number 1 in Figure 1 indicates as a whole a device for feeding sheets 2 to a wrapping line 3 (shown only partly) of a known cigarette packing machine (not shown). More specifically, sheets 2 are labels, each of which is applied by wrapping line 3 to the outside of a respective packet of cigarettes (not shown). Feed device 1 comprises two vertical hoppers 4, each containing a respective stack 5 of sheets 2, and each having a respective bottom output opening 6 defining a pickup position 7 of sheets 2. Feed device 1 also comprises two suction pickup rollers 8, each having a respective axis 9 perpendicular to the Figure 1 plane, and each activated by a common actuating device 10 to withdraw a respective sheet 2 in pickup position 7, and to feed sheet 2 to a respective intermediate suction roller 11 having an axis 12 parallel to axes 9. From intermediate rollers 11, sheets 2 are transferred in known manner to a single suction input roller 13 of wrapping line 3 and then applied to respective packets of cigarettes (not shown). The above pickup rollers 8 may be replaced by different known rotary pickup members of other than substantially cylindrical shape. As shown in Figure 4, in actual use, actuating device 10 imparts to each pickup roller 8 a rolling movement in contact with a respective sheet 2 in pickup position 7, so as to at least partly wind each sheet 2 about respective pickup roller 8. The rolling movement is imparted to each pickup roller 8 by actuating device 10 moving each pickup roller 8 in a traveling direction 14 perpendicular to respective axis 9, and at the same time rotating each pickup roller 8 about respective axis 9. Actuating device 10 then imparts to each pickup roller 8 a further rolling movement in contact with respective intermediate roller 11 to assist release of respective sheet 2 to respective intermediate roller 11; the rolling movement is imparted to each pickup roller 8 by combining a rotation of each pickup roller 8 about respective axis 9 with a rotation of respective intermediate roller 11 about respective axis 12. During release of each sheet 2 from respective pickup roller 8 to respective intermediate roller 11, each pickup roller 8 is rotated at the same surface speed but in the opposite direction with respect to respective intermediate roller 11. In an alternative embodiment not shown, each intermediate roller 11 is replaced by a different type of intermediate conveyor. In the alternative embodiment, once respective sheet 2 has been picked up, each pickup roller 8 continues rotating about respective axis 9 to assist release of respective sheet 2 to the corresponding intermediate conveyor. As each sheet 2 is fed from respective hopper 4 to respective intermediate roller 11, therefore, actuating device 10 moves said pickup roller 8 in direction 14 according to a given law of motion comprising an initial forward stage (shown in Figures 4a and 4b) to pick up sheet 2 and bring pickup roller 8 into a release position tangent to respective intermediate roller 11; a hold stage (shown in Figures 4c and 4d) to release sheet 2 to intermediate roller 11, and wherein the central axis 9 of rotation of pickup roller 8 is maintained in a fixed position; and a final return stage (shown in Figure 4e). In the course of the forward and hold stages, each pickup roller 8 rotates continuously and substantially uninterruptedly anticlockwise about respective axis 9, whereas, in the course of the return stage, each pickup roller 8 rotates clockwise about respective axis 9. In the preferred embodiment shown in the accompanying drawings, each sheet 2 is wound completely about respective pickup roller 8, which then rotates about respective axis 9 until sheet 2 is released completely to respective intermediate roller 11. In an alternative embodiment, each pickup roller 8 only rotates about respective axis 9 until an initial portion of respective sheet 2 has been transferred to corresponding intermediate roller 11. Pickup rollers 8, intermediate rollers 11 and input roller 13 are known suction rollers, each of which gradually activates suction through its lateral surface during pickup of respective sheet 2, and gradually deactivates suction through its lateral surface during release of respective sheet 2. For example, as shown in Figure 4a, each suction pickup roller 8 comprises a cylindrical inner body 15 having a suction chamber 16 connected to a suction pump (not shown), and a release chamber 17 connected to the outside environment; and a cylindrical outer shell 18, which is coaxial with cylindrical inner body 15, rotates with respect to cylindrical inner body 15, and has a respective lateral surface 19 having a number of through holes 20 and for receiving said sheet. As cylindrical outer shell 18 rotates, holes 20 communicate cyclically with chambers 16 and 17 to gradually and respectively activate and deactivate suction through lateral surface 19. During transfer from respective pickup roller 8 to respective intermediate roller 11, each sheet 2 is therefore subjected to very little stress, by virtue of respective roller 8 rotating about respective axis 9 and so enabling roller 8 to accompany respective sheet 2 onto respective intermediate roller 11. As shown in Figure 1, actuating device 10 comprises a frame 21 supporting each pickup roller 8 for rotation about respective central axis 9; an actuating device 22 for moving frame 21 back and forth linearly in traveling direction 14; and an actuating device 23 for oscillating each pickup roller 8 about respective central axis 9. Actuating device 22 comprises a deformable articulated polygon 24, in turn comprising frame 21 and which is deformable to move frame 21 in traveling direction 14; and a reversible motor 25 for applying a force to deformable articulated polygon 24 to move frame 21 in traveling direction 14. Articulated polygon 24 is carried by a structure 26 supporting feed device 1, and comprises an arm 27 hinged at one end to frame 21; a triangular element 28 hinged to frame 21; an arm 29 hinged at one end to arm 27 and at the opposite end to supporting structure 26; an arm 30 hinged at one end to triangular element 28 and at the opposite end to supporting structure 26; and an arm 31 parallel to frame 21 and hinged at opposite ends to intermediate points of arms 29 and 30. Motor 25 is connected to triangular element 28 via the interposition of an arm 32, which is hinged at one end to triangular element 28 and is fitted at the opposite end to a shaft of motor 25. Actuating device 23 comprises a gear 33 fitted in rotary manner to frame 21 to oscillate about a respective axis 34 parallel to axes 9; two gears 35, each connected to gear 33 and integral with a respective pickup roller 8; and a reversible motor 36 for oscillating gear 33 about axis 34 by means of a known lever transmission mechanism 37.

Claims: A method of feeding sheets to a wrapping line, the method comprising a first transfer step in which sheets (2) are fed successively into a pickup position (7); for each sheet (2) in the pickup position (7), a second transfer step in which a suction pickup roller (8) is rolled along the sheet (2) to at least partly wind the sheet (2) about the pickup roller (8); and a third transfer step in which the sheet (2) is released to an intermediate conveyor (11); in the course of said third transfer step the pickup roller (8) being rotated about a respective central axis (9) to assist release of the sheet (2) to the intermediate conveyor (11); and the method being characterized in that in the course of said third transfer step said central axis (9) of rotation of said pickup roller (8) is maintained in a fixed position and said pickup roller (8) is rolled in contact with said intermediate conveyor (11) to release the sheet (2) wound about the pickup roller to the intermediate conveyor (11). A method as claimed in Claim 1, wherein, in the course of said second transfer step, said pickup roller (8) is rolled against said sheet (2) in the pickup position (7) by translating the pickup roller (8) in a traveling direction (14) perpendicular to said central axis (9) of rotation of the pickup roller (8). A method as claimed in Claim 1 or 2, wherein, in the course of said second transfer step, said sheet (2) in the pickup position (7) is wound completely about said pickup roller (8). A method as claimed in any one of Claims 1 to 3, wherein, in the course of said third transfer step, said pickup roller (8) is rotated a given angle about the respective central axis (9) of rotation so that at least an initial portion of said sheet (2) is engaged by said intermediate conveyor (11). A method as claimed in any one of Claims 1 to 4, wherein, in the course of said third transfer step, said pickup roller (8) is rotated a given angle about the respective central axis (9) so that substantially the whole of said sheet (2) is engaged by said intermediate conveyor (11). A method as claimed in any one of Claims 1 to 5, wherein, in the course of said second transfer step, said sheet (2) is wound along a first lateral suction surface (19) of said pickup roller (8); suction through said first lateral suction surface (19) being activated gradually during said second transfer step, and deactivated gradually during said third transfer step. A method as claimed in any one of Claims 1 to 6, wherein said intermediate conveyor (11) is defined by a suction conveyor roller (11) having a second lateral suction surface for receiving said sheet (2); said pickup roller (8) being tangent to said conveyor roller (11) during said third transfer step; and suction through said second lateral suction surface being activated gradually during said third transfer step. A method as claimed in Claim 7, wherein, in the course of said third transfer step, the pickup roller (8) is rotated at the same surface speed but in the opposite direction with respect to said conveyor roller (11). A method as claimed in one of Claims 1 to 8, wherein, in the course of said transfer steps, said pickup roller (8) is rotated in the same direction at all times about the respective central axis (9) of rotation. A device for feeding a sheet to a wrapping line; the device comprising transfer means (4) for feeding sheets (2) successively into a pickup position (7); at least one suction pickup roller (8) having a central first axis (9) of rotation; at least one intermediate conveyor (11); and actuating means (10) for imparting to said pickup roller (8) a first rolling movement in contact with a said sheet (2) in the pickup position (7), so as to at least partly wind the sheet (2) about the pickup roller (8); the device being characterized in that said actuating means (10) impart to said pickup roller (8) a second rolling movement in contact with said intermediate conveyor (11), to assist release of said sheet (2) to said intermediate conveyor (11). A device as claimed in Claim 10, wherein said transfer means (4) comprise a hopper (4) for a stack (5) of said sheets (2) and having a bottom opening (6) defining said pickup position (7). A device as claimed in Claim 10 or 11, wherein said actuating means (10) imparts to said pickup roller (8) a first and a second rotation about the central said first axis (9) in the course of said first and said second rolling movement respectively, moving said pickup roller (8) crosswise to the central said first axis (9) to and from a release position, and maintaining the pickup roller (8) fixed in said release position. A device as claimed in Claim 12, wherein said first and second rotation are in the same direction. A device as claimed in Claim 12 or 13, wherein said intermediate conveyor (11) is defined by a suction conveyor roller (11) having a second axis (12) parallel to said first axis (9); during release of said sheet (2) to said intermediate conveyor (11), said pickup roller (8) being tangent to said conveyor roller (11). A device as claimed in any one of Claims 10 to 14, wherein said suction pickup roller (8) comprises a cylindrical inner body (15) having at least a suction chamber (16); and a cylindrical outer shell (18), which is coaxial with said cylindrical inner body (15), rotates with respect to the cylindrical inner body (15), and has a respective lateral surface (19) having a number of through holes (20) and for receiving said sheet (2). A device as claimed in any one of Claims 10 to 15, wherein said actuating means (10) comprise a frame (21) supporting said pickup roller (8) for rotation about a respective central first axis (9); a first actuating device (22) for moving said frame (21) back and forth linearly in a traveling direction (14) perpendicular to said first axis (9); and a second actuating device (23) for oscillating said pickup roller (8) about the central said first axis (9). A device as claimed in Claim 16, wherein said first actuating device (22) comprises a deformable articulated polygon (24), which in turn comprises said frame (21) and is deformable to move said frame (21) in said traveling direction (14); and a reversible first motor (25) for applying a force to said deformable articulated polygon (24). A device as claimed in Claim 17, and comprising a fixed body (26) supporting said articulated polygon (24); the articulated polygon (24) comprising a first arm (27) hinged at one end to said frame (21), a triangular element (28) hinged to said frame (21), a second arm (29) hinged at one end to said first arm (27) and at an opposite end to said fixed body (26), a third arm (30) hinged at one end to said triangular element (28) and at an opposite end to said fixed body (26), and a fourth arm (31) which is parallel to said frame (21) and hinged at opposite ends to intermediate points of said second and said third arm (29, 30). A device as claimed in Claim 18, wherein said first motor (25) is connected to said triangular element (28); said first actuating device (22) comprising a fifth arm (32) which is hinged at one end to said triangular element (28) and is fitted at an opposite end to a shaft of said first motor (25). A device as claimed in any one of Claims 16 to 19, wherein said second actuating device (23) comprises a first gear (33) mounted for rotation to said frame (21) to oscillate about a third axis (34) parallel to said first axis (9); a second gear (35) connected to said first gear (33) and integral with said pickup roller (8); and a reversible second motor (36) for oscillating said first gear (33) about said third axis (34). A device as claimed in Claim 20, wherein said second motor (36) is connected to said first gear (33) by a lever transmission mechanism (37). A device as claimed in any one of Claims 11 to 21, and comprising two said hoppers (4), each containing a respective stack (5) of sheets (2) and having a respective outlet opening (6); two said suction pickup rollers (8), each operating with a respective said hopper (4); and two said intermediate conveyors (11), each operating with a respective said pickup roller (8); said actuating means (10) being connected to both said pickup rollers (8). A device as claimed in Claim 16 or 22, wherein said frame (21) supports both said pickup rollers (8) for rotation about respective central said first axes (9).

Inventors: DRAGHETTI FIORENZO, ZANETTI UMBERTO, DRAGHETTI, FIORENZO, ZANETTI, UMBERTO
Applicants: GD SPA, G.D SOCIETA' PER AZIONI
Application year: 2000
Main classification: B65H3
IPC codes: B65H3