|
(11) | EP 1 201 579 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Method and device for picking up reams of sheets |
| (57) A method and device for picking up reams (2) of sheets (3) off a stack (4) of sheets
(3) on a supporting pallet (5), wherein a last ream (2'), defined by an N number of
sheets (3), is picked up off the pallet (5) by a first pickup device (33) for picking
up a first group (52) of N-M sheets (3), and by a second pickup device (34) for picking
up a second group (53) of M sheets (3). |
[0002] As is known, to package reams of sheets, a device is employed to pick up reams of sheets successively off a stack of sheets supported on a pallet.
[0003] Each ream normally comprises a given N number of sheets, and the pallet is loaded with a number of sheets which is a whole multiple of N enabling the formation and pickup of a given X number of reams.
[0004] The device is normally equipped with a gauge comprising a top jaw, which is placed on the top surface of the stack, and a bottom jaw defined by a knife, which is inserted inside the stack at a distance from the top jaw equal to the thickness of a ream, so as to select a ream from the stack at each operating cycle of the device. The gauge also raises the selected ream at least partly, to enable pickup and feed means to be inserted inside the stack, to pick up the selected ream, and to feed the picked-up ream to an input station of an operating unit.
[0005] Known devices of the above type have several drawbacks, foremost of which is that they fail to provide for correctly selecting and, hence, picking up the last ream off the pallet. That is, to select the last ream of N sheets, the knife would have to be inserted between the pallet and the bottom sheet in the stack, and may interfere with the pallet, thus resulting in damage and/or breakage of the knife.
[0006] At present, therefore, known devices of the above type are operated to leave the last ream on the pallet, which is normally treated as waste. As the sheets of some types of paper material, however, have a relatively high unit cost, known devices of the above type involve considerable financial loss.
[0007] It is an object of the present invention to provide a method of picking up reams of sheets, designed to eliminate the aforementioned drawbacks.
[0008] According to the present invention, there is provided a method of picking up reams of sheets off a stack of sheets on a supporting pallet; said stack comprising an X number of said reams, and each said ream comprising an N number of said sheets; and the method comprising the step of successively picking up X-1 reams by means of first pickup means; and being characterized by also comprising the steps of picking up from a last ream on said pallet a first group of N-M sheets by means of said first pickup means, and a second group of M sheets by means of second pickup means.
[0010] According to the present invention, there is provided a device for picking up a ream of N sheets off a supporting pallet; said ream comprising a first group of N-M sheets, and a second group of M sheets; and the device being characterized by comprising first pickup means for picking up said first group; and second pickup means for picking up said second group off said pallet.
[0011] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Figure 1 shows a schematic view in perspective, with parts in section and parts removed for clarity, of a preferred embodiment of the device according to the present invention;
Figures 2 and 3 show larger-scale views in perspective of a Figure 1 detail in two different operating positions;
Figures 4 to 9 show, schematically and with parts removed for clarity, the Figure 1 device in successive operating positions.
[0012] Number 1 in Figure 1 indicates as a whole a device for picking up reams 2 (Figure 5) of sheets 3 off a stack 4 of sheets 3 on a supporting pallet 5. Each ream 2 is defined by an N number of sheets 3, and stack 4 is defined by a number of sheets 3 which is a whole multiple of N, so as to enable an X number of reams 2 to be picked up off pallet 5.
[0013] By means of a known actuating device not shown, pallet 5 is moved in a substantially vertical direction 6 to feed reams 2 successively, along a path P parallel to direction 6, to a pickup and transfer station 7 of device 1, which selects each ream 2 from stack 4, picks up the selected ream 2, and feeds the picked-up ream 2 in a substantially horizontal direction 8 crosswise to direction 6, to transfer ream 2 to an input station 9 of a known operating unit not shown.
[0014] Device 1 has a known selecting device 10 for selecting each ream 2 from stack 4, and which comprises a slide 11 fitted in known manner to a frame (not shown) of the operating unit (not shown) to move linearly with respect to the frame in directions 6 and 8.
[0015] Device 10 also comprises a gauge 12, in turn comprising a top jaw 13 defined at the bottom by a substantially flat surface 14, and a bottom jaw defined by a substantially flat knife 15 extending parallel to surface 14, and the distance of which from surface 14 is adjustable manually or by means of a known actuating device not shown. Knife 15 is connected in sliding manner to jaw 13 so as to move - with respect to jaw 13 and by virtue of two parallel actuating cylinders 16 - parallel to surface 14 to penetrate stack 4.
[0016] Jaw 13 is connected in rotary manner to slide 11 to oscillate - with respect to slide 11 and by virtue of a known actuating device 17 - about an axis 18 perpendicular to directions 6 and 8, and so move gauge 12 between a substantially horizontal position (Figure 4) in which to select ream 2, and a tilted position (Figure 5) in which a rear portion of the selected ream 2 is raised off stack 4.
[0017] Device 17 comprises a crank 19, which is oscillated about axis 18 by an actuating cylinder 20 hinged to slide 11 and having an output rod 21, a free end of which is mounted to slide, via the interposition of a pin 22 substantially parallel to axis 18, inside a slot 23 formed through crank 19. Rod 21 is movable between a withdrawn position and an extracted position so that crank 19 engages or releases a pin 24 - substantially parallel to axis 18 and integral with jaw 13 - to move gauge 12 between the horizontal and titled positions.
[0018] Device 1 also comprises a known pressure member 25 defined by a substantially flat plate 26 crosswise to direction 6 and fitted to the free end of the output rod of an actuating cylinder 27, which moves plate 26 in direction 6 and is carried by the output rod of an actuating cylinder 28 for moving cylinder 27, and hence plate 26, in direction 8.
[0019] Finally, device 1 also comprises a pickup and transfer unit 29, in turn comprising a slide 30 fitted in known manner to said frame (not shown) of said operating unit (not shown) to move linearly in directions 6 and 8 with respect to the frame (not shown).
[0020] With reference to Figures 2 and 3, unit 29 also comprises two pickup and transfer devices 31 aligned in a direction 32 substantially parallel to axis 18, and located substantially on opposite sides of the whole defined by selecting device 10 and pressure member 25.
[0021] Each device 31 comprises a substantially C-shaped pickup and transfer member 33 fitted to slide 30 with its concavity facing stack 4; and a gripping member 34 fitted to member 33, on the opposite side to stack 4, via the interposition of a flat plate 35 fixed to member 33 and crosswise to direction 8.
[0022] Member 34 comprises an elongated flat plate 36, which is crosswise to direction 6, has at least one suction cup 37 connected to a known suction device not shown, and is fitted to the bottom end of a screw 38 having a longitudinal axis 39 substantially parallel to direction 6. Screw 38 is fitted in rotary and axially-sliding manner through a supporting plate 40 perpendicular to plate 35, and is connected in angularly-fixed manner - at the top end and by means of a clamp 41 coaxial with axis 39 - to the output shaft (not shown) of a known rotary pneumatic actuating cylinder 42, so as to oscillate with respect to plate 40 and about axis 39 as described in detail later on.
[0023] Cylinder 42 has a substantially parallelepiped-shaped collar 43, which extends about axis 39, is fitted through with the output shaft (not shown) of cylinder 42, and has two faces 44 parallel to each other and to plate 35, and two faces 45 parallel to each other and perpendicular to faces 44.
[0024] Screw 38 is connected to a nut screw 46 by means of a screw-nut screw coupling 47 of a relative actuating device 48. Device 48 comprises a motor 49 supported on plate 40 and having an output shaft 50, which is substantially parallel to screw 38 and connected to nut screw 46 by a belt transmission 51 for rotating nut screw 46 about axis 39 to move screw 38 linearly in direction 6.
[0025] In connection with the above, it should be pointed out that:
screw 38 is maintained in a given angular position by the compressed air of cylinder 42; and
collar 43 allows the whole defined by screw 38 and cylinder 42 to be moved by motor 49 in direction 6 without taking part in the rotation of nut screw 46 about axis 39.
[0026] Operation of device 1 will now be described with reference to Figures 4 to 9, and as of an instant in which:
both gripping members 34 are set to respective rest positions (Figure 2) in which respective plates 36 are located outwards of path P; and
gauge 12 is adjusted so that the distance between knife 15 and surface 14 of top jaw 13 equals the thickness of the N sheets 3 defining each ream 2.
[0027] With reference to Figure 4, gauge 12 is moved in direction 6 and in the horizontal position to bring surface 14 into contact with stack 4; and knife 15 is moved in direction 8 by means of relative actuating cylinders 16 so as to penetrate stack 4 to select a first ream 2.
[0028] With reference to Figure 5, gauge 12 is then moved by actuating device 17 into the tilted position to partly raise the selected ream 2; pressure member 25 is moved in directions 6 and 8 so as to contact and retain the top sheet 3 of the next ream 2; and both pickup and transfer devices 31 are moved in directions 6 and 8 to insert respective pickup and transfer members 33 beneath the raised ream 2 and transfer ream 2 in direction 8 to input station 9 of the operating unit (not shown).
[0029] Gauge 12, member 25, and unit 29 are then restored to their original positions to repeat the above operating sequence and transfer the first X-1 reams 2 in stack 4 to input station 9.
[0030] Once the first X-1 reams 2 have been picked up and transferred to input station 9, gauge 12 is adjusted, manually or by means of the respective actuating device (not shown), to set knife 15 to a distance from surface 14 equal to the thickness of N-M sheets 3.
[0031] With reference to Figure 4, gauge 12 is moved in direction 6 and in the horizontal position to bring surface 14 into contact with the top sheet 3 of a last ream 2 (hereinafter referred to as ream 2'); and knife 15 is moved in direction 8 by means of relative actuating cylinders 16 so as to penetrate ream 2' to select a group 52 of sheets 3 defined by N-M sheets 3.
[0032] With reference to Figure 5, gauge 12 is then moved by actuating device 17 into the tilted position to partly raise group 52 and to keep group 52 partly contacting a group 53 of sheets 3 defined by the remaining M sheets 3; and both pickup and transfer devices 31 are moved in directions 6 and 8 to insert respective members 33 beneath group 52.
[0033] At this point, pallet 5 is lowered in direction 6 to make room to maneuver gripping members 34; one of members 34 (hereinafter referred to as member 34a) is moved by respective actuating device 48 in direction 6 to position respective plate 36 beneath respective member 33; actuating cylinder 42 of member 34a is activated to rotate respective plate 36 substantially 90° about respective axis 39 and so set respective plate 36 to an operating position interfering with path P; and member 34a is first lowered, so that respective suction cup 37 engages the top sheet 3 (hereinafter referred to as sheet 31) in group 53, and is then raised to partly detach sheet 31 from group 53 (Figure 6).
[0034] With member 34a still in the operating position, the operating sequence described for member 34a is repeated for the other member 34 (hereinafter referred to as member 34b) so as to pick up a second sheet 3 (hereinafter referred to as sheet 32) in group 53. At this point, suction cup 37 of member 34a is deactivated; sheet 31 drops on to and is supported by plate 36 of member 34b (Figure 7); member 34a is moved into the rest position; and the above operating sequence is repeated alternately, once for member 34a and once for member 34b, to pick up all M sheets 3 in group 53 one at a time.
[0035] In connection with the above, it should be pointed out that, when one of members 34a, 34b is moved into the rest position to repeat the above operating sequence and pick up the next sheet 3 in group 53, the other member 34a, 34b remains in the operating position to support all the sheets 3 in group 53 already picked up.
[0036] When the last sheet 3 in group 53 has been picked up, e.g. by member 34a, member 34b is moved into the rest position, repeats the above operating sequence without picking up any sheet 3, and is maintained in the operating position so as to be positioned beneath group 53; and member 34a is moved into the rest position so that member 34b supports all the sheets 3 in group 53.
[0037] With member 34b still in the operating position, member 25 is moved in directions 6 and 8 so that respective plate 26 is positioned beneath the bottom sheet 3 in group 53; and member 34b is moved into the rest position so that all the sheets 3 in group 53 drop on to and are supported by plate 26 (Figure 8).
[0038] With reference to Figure 9, slide 30 is moved in direction 8 so that both members 33 release group 52, the sheets 3 of which drop on to and are supported by sheets 3 in group 53, i.e. by member 25. Finally, slide 30 is moved in directions 6 and 8 to enable both members 33 to engage the last ream 2'; member 25 releases the last ream 2'; and slide 30 is moved in direction 8 to transfer the last ream 2' to input station 9 of the operating unit (not shown).
1. A method of picking up reams (2) of sheets (3) off a stack (4) of sheets (3) on a
supporting pallet (5); said stack (4) comprising an X number of said reams (2), and
each said ream (2) comprising an N number of said sheets (3); and the method comprising
the step of successively picking up X-1 reams (2) by means of first pickup means (33);
and being characterized by also comprising the steps of picking up from a last ream (2') on said pallet (5)
a first group (52) of N-M sheets (3) by means of said first pickup means (33), and
a second group (53) of M sheets (3) by means of second pickup means (34).
2. A method as claimed in Claim 1, wherein said sheets (3) in said second group (53)
are picked up one by one.
3. A method as claimed in Claim 1 or 2, wherein said second pickup means (34) comprise
at least two pickup members (34); said pickup members (34) being activated alternately
to pick up the sheets (3) in said second group (53) one by one.
4. A method as claimed in Claim 3, wherein said stack (4) is moved along a given path
(P); each said pickup member (34) being movable between a respective operating position
wherein the pickup member (34) interferes with said path (P), and a respective rest
position wherein the pickup member (34) is located outwards of the path (P).
5. A method as claimed in Claim 4, wherein each of said pickup members (34) is moved
into the operating position both to pick up a sheet (3) in said second group (53),
and to support the sheets (3) in the second group (53) already picked up.
6. A method as claimed in Claim 4 or 5, and also comprising, at the end of the step to
pick up said second group (53), a first supporting step wherein said pickup members
(34) are moved into their rest positions, and said second group (53) is supported
by a supporting member (25) movable to and from a supporting position wherein the
supporting member (25) interferes with said path (P).
7. A method as claimed in Claim 6, and also comprising a second supporting step wherein
said first (52) and said second (53) group are combined to form said last ream (2').
8. A method as claimed in Claim 7, wherein, at said second supporting step, said first
pickup means (33) are moved outwards of said path (P) so that said first group (52)
is brought into contact with said second group (53).
9. A method as claimed in Claim 7 or 8, and also comprising a third supporting step wherein
said first pickup means (33) and said supporting member (25) are moved inwards and
outwards of said path (P) respectively.
10. A method as claimed in any one of the foregoing Claims, wherein, in the course of
the step to pick up said second group (53), said first group (52) is maintained partly
contacting the second group (53).
11. A method as claimed in any one of the foregoing Claims, wherein said X-1 reams (2)
and said first group (52) are selected from said stack (4) by the same selecting device
(10).
12. A device for picking up a ream (2) of N sheets (3) off a supporting pallet (5); said
ream (2) comprising a first group (52) of N-M sheets (3), and a second group (53)
of M sheets (3); and the device being characterized by comprising first pickup means (33) for picking up said first group (52); and second
pickup means (34) for picking up said second group (53) off said pallet (5).
13. A device as claimed in Claim 12, wherein said second pickup means (34) comprise at
least two pickup members (34) activated alternately to each pick up a respective sheet
(3) in said second group (53).
14. A device as claimed in Claim 13, and comprising, for each said pickup member (34),
actuating means (42, 48) for moving the relative pickup member (34) to and from an
operating position wherein the relative pickup member (34) is located beneath said
first group (52).
15. A device as claimed in Claim 14, wherein each said pickup member (34) is so formed
that, when in the operating position, the pickup member (34) provides for both picking
up a sheet (3) in said second group (53), and supporting the sheets (3) in the second
group (53) already picked up.
16. A device as claimed in Claim 14 or 15, wherein said actuating means (42, 48) comprise
first actuating means (48) for imparting to the relative pickup member (34) straight
movements in a given direction (6); and second actuating means (42) for imparting
to the relative pickup member (34) a rotary movement about an axis (39) substantially
parallel to said given direction (6).
17. A device as claimed in Claim 16, wherein said first actuating means (48) comprise
a motor (49), and a screw-nut screw coupling (47) interposed between the motor (49)
and the relative said pickup member (34).
18. A device as claimed in Claim 17, wherein said screw-nut screw coupling (47) comprises
a screw (38) having said axis (39) and associated with the relative said pickup member
(34), and a nut screw (46) associated with said motor (49); said second actuating
means (42) being associated with said screw (38).
19. A device as claimed in Claim 18, wherein said second actuating means (42) comprise
a rotary actuating cylinder having an output shaft connected in angularly-fixed manner
to said screw (38).
20. A device as claimed in any one of Claims 12 to 19, and also comprising selecting means
(10) for selecting said first group (52).
21. A device as claimed in any one of Claims 12 to 20, and also comprising supporting
means (25) for supporting the ream (2) picked up off said pallet (5), so as to enable
said first (33) and second (34) pickup means to move into respective rest positions
wherein the first (33) and second (34) pickup means are located alongside the ream
(2).