Device for stacking sheets and digital printing machine

Abstract

A device for stacking sheets (1) comprises a mechanism for forming a stack of sheets (28) from alternately offset stacks of sheets (26, 30). A support (27) for carrying a completed stack of sheets (26) is provided. A catcher (3) for catching the lowest sheet (1) of a stack of sheets (30) yet to be completed and a pusher (4) for pressing the uppermost sheet (1) of the completed stack of sheets (26) onto the completed stack of sheets (26) are provided. The pusher (4) is mounted so as to be displaceable relative to the catcher (4) transversely to a sheet travel direction.

Description

[0001] The present invention relates to a device for stacking sheets, comprising a device for forming a stack of sheets from alternately offset sheet stacks.

[0002] Such devices can be used, for example, in calendar printing in a digital printing machine, whereby the calendar pages of the respective copy are printed one after the other and together form a stack of sheets.

[0003] A device corresponding to the aforementioned type is described, for example, in DE 24 43 106 A1.

[0004] Further state of the art is represented by JP S62 - 46 862 A.

[0005] The object of the invention is to create a further device for stacking sheets.

[0006] The problem is solved by a device for stacking sheets, comprising a device for forming a stack of sheets from alternately offset stacks of sheets, characterized in that a catcher is provided for catching a bottom sheet of a stack of sheets yet to be completed, that a support is provided for carrying a stack of sheets already completed, that a pusher is provided for pressing a top sheet of the stack of sheets already completed onto the stack of sheets already completed, and that the pusher is mounted to be displaceable relative to the catcher transversely to a sheet travel direction.

[0007] One advantage of the device according to the invention is that it enables a rapid assembly of the sheet stack in high quality.

[0008] The following further developments of the device according to the invention are possible individually or in any combination with each other: The catch and the pusher can be arranged on one and the same arm, in particular on one and the same arm of a coupling mechanism.

[0009] The coupling mechanism can be driven by a cam mechanism.

[0010] The push button can be mounted in a linear guide on the catcher.

[0011] The catcher can be designed as a suction cup and hold the lowest arc of the bow stroke that is yet to be completed by means of suction.

[0012] The device can be a component of a digital printing machine.

[0013] Further information can also be obtained from the following description of an exemplary embodiment and the associated drawing.

[0014] It shows: Fig. Figures 1 to 4 show a side view of a gear diagram of a sheet stacking device in various operating positions. Fig. 5 a front view of the sheet stacking device in a Fig. 1 corresponding operating position and Fig. 6 a front view of the sheet stacking device in a Fig. 2 corresponding operating positions.

[0015] In the Fig. Figures 1 to 6 depict a sheet stacking device of an inkjet printing press. The sheets 1 printed in the machine are transported to the device in a sheet feed direction 2. The device comprises a catcher 3 and a pusher 4, which are arranged on an arm 5 that forms the coupling of a linkage 6. The catcher 3 and pusher 4 are in the Fig. 1 to 4 are schematically represented and in the Fig. 5 and Fig. Figure 6 shows in detail. The catcher 3 has an upwardly facing suction surface 4 with suction openings 8 for drawing in the sheet 1. The pusher 4 has a downwardly facing contact surface 9 and is connected to the catcher 3 via a linear guide 10 such that the pusher 4 can be moved horizontally relative to the catcher 3 in the lateral direction 11 transversely to the sheet travel direction 2.

[0016] The arm 5 is connected via joints 12, 13 to swing arms 14, 15, which are mounted in a frame 18 via joints 16, 17. A cam roller 19 is arranged on the arm 5, which runs on a cam disk 20. Another cam roller 21 is arranged on the swing arm 15, which runs on another cam disk 22. The cam disks 20, 22 are mounted on a drive shaft 23 and are driven together by it rotationally. The cam disks 20, 22 and cam rollers 19, 21 together form a cam drive 24, which drives the coupling mechanism 6, so that the arm 5 with the catch 3 and pusher 4 moves the Fig. The movement phases shown in 1 to 4 are completed sequentially.

[0017] In the first movement phase after Fig. 1 and Fig. As the arc 1 approaches the leading end 25 of a lower arc stack 26 (in the arc travel direction 2), which is supported by a beam 27, the catch 3 and pusher 4 are in waiting positions above the transport path of the incoming arc 1. After the arc 1 reaches the end 25, where it is stopped by arc leading edge stops (not shown), the cam discs 20 and 22 continue to rotate. This moves the catch 3 and pusher 4 towards the arc stack 28, whose lower arc stack 26 is now complete. The uppermost arc 1 of the lower arc stack 26 is pressed onto the lower arc stack 26 by the pusher 4.

[0018] In the second phase of movement after Fig. 2 and Fig. 6 The next sheet 1 falls onto the catcher 3, which holds it with its suction openings 8. The subsequent sheets 1 are then picked up by the catcher 3. In this state, when the sheet 1 under the pusher 4 is pressed by it onto the sheet stack 28 and simultaneously the sheet 1 above the catcher 3 is drawn in by the latter, the carrier 27 travels a defined path in the lateral direction 11. For this purpose, the carrier 27 is driven by a drive mechanism not shown in the drawing. The pusher 4 travels this defined path together with the carrier 27 and the lower sheet stack 26 resting on it. The pusher 4 is carried along by friction by the sheet stack 26 on which it pushes and consequently moves along the linear guide 10 relative to the catcher 3.The defined path in question corresponds to a lateral offset 29 between the lower arch 26 and an upper arch 30, which together with the lower arch 26 and further arches is to form the arch stack 28.

[0019] Fig. Figure 3 shows a third phase of movement in which the cam disk 20,22 continue to rotate and as a result the catcher 3 and pusher 4 are pulled out of the arc stack 28 in the arc travel direction 2 after the lower arc stack 26 has reached its end position with the lateral offset 29 relative to the upper arc stack 30.

[0020] Fig. Figure 4 shows a fourth movement phase in which the cam disc 20, 22 continue to rotate until the catcher 3 and pusher 4 reach their positions. Fig. have returned to the starting position shown in point 1.

[0021] After completion of the upper arch section 30, the support 27 is returned to its starting position in the opposite direction 11 according to Fig.5 procedure so that a third arch, which is placed congruently with the lower arch 26 without offset 29, can be stacked on the upper arch 30.

[0022] The described movement cycle is repeated until the stack of bows 28 is complete, consisting of alternating laterally offset and non-offset bow strokes. The following modification is possible: The cam mechanism 24 can be replaced by two drives which are controlled in such a coordinated manner that they move the arm 5 with the catch 3 and push button 4 according to the described movement phases. Reference symbol list 1 sheet 2 Bow direction 3 catchers 4 push buttons 5 arms 6 coupling gears 7 Suction surface 8 Suction opening 9 Contact surface 10 linear guides 11 Side direction 12 joint 13 joint 14 Swing arm 15 swing arms 16 joint 17 joint 18 frame 19 Curve roll 20 cam disc 21 Curve roller 22 Cam disc 23 Drive shaft 24 cam gears 25 End 26 Bow Throw 27 carriers 28 stacks of sheets 29 Offset 30 Bow Throw QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 24 43 106 A1

[0003] JP S62 - 46 862

[0004]

Claims

[1] Device for stacking sheets (1), comprising a device for forming a stack of sheets (28) from alternately offset stacks of sheets (26, 30) characterized by , that a catcher (3) is available to catch the lowest bow (1) of a bow thrust (30) that is yet to be completed, that a support (27) is available for carrying an already completed bow stack (26), that a pusher (4) is provided for pressing an uppermost arc (1) of the already completed arc stack (26) onto the already completed arc stack (26), and that the push button (4) is mounted so as to be displaceable relative to the catch (4) transversely to a bow direction (2). [2] Device according to claim 1, characterized by , that the catcher (3) and the pusher (4) are arranged on one and the same arm (5) of a coupling mechanism (6). [3] Device according to claim 2, characterized by, that the coupling mechanism (6) is driven by a cam mechanism (24). [4] Device according to any one of claims 1 to 3, characterized by , that the push button (4) is mounted in a linear guide (10) on the catch (4). [5] Device according to any one of claims 1 to 3, characterized by , that the catcher (3) is designed as a suction cup and holds the lowest bow (1) of the bow stroke (30) to be completed by suction action. [6] Device according to any one of claims 1 to 3, characterized by that the device is a component of a digital printing machine.

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