Sheet transport device

Abstract

A sheet transport device of a digital printing press comprises a chain conveyor (2) with support segments (3) for supporting printed sheets, wherein the support segments (3) form a conveying plane. The support segments (3) have recesses (6) in which at least one circumferential separating element (7) for separating the printed sheets from the conveying plane is arranged. The separating element (7) is annular and has a linear element section that runs in a sheet conveying direction. The separating element (7) is narrower than the support segments (3) transversely to the sheet conveying direction (9). The element section projects beyond the support segments (3) in the sheet conveying direction. An annular movement path of the support segments (3) lies completely within an annular movement path of the separating element (7).

Description

[0001] The present invention relates to a sheet transport device of a digital printing machine, comprising a chain conveyor with support segments for supporting printed sheets, wherein the support segments form a conveying plane and have recesses in which at least one circumferential separating element for separating the printed sheets from the conveying plane is arranged, the separating element is annular and has a linear element section which runs in a sheet conveying direction, the separating element is narrower than the support segments transversely to the sheet conveying direction and wherein the element section projects beyond the support segments in the sheet conveying direction.

[0002] Such devices transport the printed sheets past print heads, which then print on the printed sheets.

[0003] DE 10 2017 110 300 A1, which represents the closest prior art, describes a device corresponding to the type mentioned above.

[0004] DE 10 2019 209 125 A1 describes a sheet transport device in a digital printing machine with trays that jointly carry a printed sheet and circulate along a ring track.

[0005] Further prior art includes DE 10 2016 204 215 A1, DE 10 2015 203 424 A1 and DE 10 2019 211 750 A1.

[0006] The object of the invention is to provide a further sheet transport device of a digital printing machine.

[0007] The object is achieved by a sheet transport device of a digital printing press, comprising a chain conveyor with support segments for supporting printed sheets, wherein the support segments form a conveying plane and have recesses in which at least one circumferential separating element for separating the printed sheets from the conveying plane is arranged, the separating element is annular and has a linear element section which runs in a sheet conveying direction, the separating element is narrower than the support segments transversely to the sheet conveying direction and wherein the element section projects beyond the support segments in the sheet conveying direction, characterized in that an annular movement path of the support segments lies completely within an annular movement path of the separating element.

[0008] The device according to the invention has the advantage that no change in the direction of the printed sheet is required during separation because the separating element runs parallel to the conveying plane.

[0009] An additional advantage is that in the event of servicing, the separation element is easy to transport and install because it is narrow. The following further training courses are possible:

[0010] The separating element and at least one further such separating element can be arranged circumferentially parallel to one another.

[0011] A common drive shaft can be provided to drive the separating elements. Guide discs on which the separating elements run can be arranged on the drive shaft.

[0012] The guide discs can be crowned.

[0013] Separating wedges can be arranged between the guide discs.

[0014] Conveyor belts can be integrated into the separating wedges.

[0015] The said element section of the or each separating element may be flush with the conveying plane.

[0016] The or each separating element can be designed as a band, rope, belt (e.g. toothed belt or V-belt) or chain.

[0017] Further developments can also be found in the following description of an embodiment and the drawing:

[0018] It shows: Fig. 1 a sheet transport device in side view, Fig. 2 the sheet transport device in plan view, Fig. 3 a sheet delivery section of the sheet transport device in detail and Fig. 4 the sheet transport device in three-dimensional representation.

[0019] In a digital printing press, a chain conveyor 2 is arranged below print heads 1. The chain conveyor 2 transports printed sheets 4 in a sheet conveying direction 9. The printed sheets 4 lie on support segments 3, each of which has a support surface for supporting the printed sheets 4. The support surface is provided with a grid of suction openings that pneumatically hold the printed sheet 4 during transport. Each printed sheet 4 is held simultaneously by several support segments 3 during transport. The support segments 3 together form a chain and rotate on a ring-shaped movement path. In the upper area of ​​the movement path, the support segments 3 form a conveying plane 5, towards which the print heads 1 are directed in order to print the printed sheets 4 using inkjet printing.

[0020] The chain conveyor 2 receives the printed sheets 4 in a sheet receiving area 16 and releases them again in a sheet delivery area 15. Several separating elements 7 - in particular steel belts, e.g., with a thickness of 0.2 to 0.3 mm - are arranged in a row running transversely to the sheet conveying direction 9. The annular or infinite separating elements 7 each rotate on an annular path of movement, within which lies the path of movement of the support segments 3. The separating elements 7 are guided by shafts 10, 18, including a drive shaft 10 arranged in the sheet delivery area 15. Each shaft 10, 18 has guide disks 11 and intermediate tapers 12. The separating elements 7 run on the guide disks 11, which can be spherical in order to center the separating elements 7 thereon.

[0021] Recesses 6, e.g. in the form of grooves, are made in each of the support segments 3. The recesses 6 of each support segment 3 are aligned in the sheet conveying direction 9 with the recesses 6 of the two adjacent support segments 3 within the chain. In the area of ​​the conveying plane 5, a linear element section 8 of the respective separating element 7 plunges into the recesses 6 of the successively arranged support segments 3, preferably so deeply that the separating element 3 is exactly flush with the supporting surface of the support element 3 and the top side of the separating element 7 coincides with the conveying plane 5. A slightly deeper immersion would also be possible with appropriate dimensioning of the recesses 6, but flushness is preferred for printing reasons. The recesses 6 are so wide transverse to the sheet conveying direction 9 that the separating elements 7 are arranged in them with existing, but as minimal as possible, lateral play.

[0022] The separating elements 7 are driven by a motor 19 via the drive shaft 10 such that they run at the same speed as the support segments 3 in the area of ​​the conveying plane 5. The synchronous operation of the separating elements 7 with the support segments 3 prevents friction between them and the resulting wear. The orbital movement of the support segments 3 can be driven by a main motor separate from the motor 19.

[0023] According to one modification, it would be possible for the motor 19 to drive the orbital movement of the support segments 3 via the separating elements 7, thereby eliminating the main motor. According to another modification, it would be possible for the motor 19 to be omitted and the drive shaft 18 to no longer be such, and for the orbital movement of the separating elements 7 to be driven by the main motor via the support segments 3. In both of the aforementioned modifications, the separating elements 7 can be designed as toothed belts, and toothings can be formed on the support segments 3, e.g., at the base of the recesses 6, into which the toothed belts engage.

[0024] In the sheet delivery area 15, the linear element section 8 of each separating element 7 forms a projection 17 over the chain conveyor 2, in that the separating elements 7 continue to run horizontally straight ahead and the support segments 3 bend downwards upon leaving the conveying plane 5. The projection 17 advantageously ensures that the printed sheet 4 detaches more easily from the support segments 3. No relative movement occurs between the separating elements 7 and the printed sheet 4 when the printed sheet 4 detaches from the chain conveyor 2. Such a projection of the separating elements 7 over the chain conveyor 2 is provided not only to the front but also to the rear, i.e. in the sheet take-over area 16, where it ensures that the printed sheet 4 is securely placed on the support segments 3, which is an additional advantage.

[0025] In the area of ​​the overhang 17, separating wedges 13 are arranged between the separating elements 7, the tips of which are directed opposite to the sheet conveying direction 9. The upper side of each separating wedge 13 is at the level of the conveying plane 5. The separating wedges 13 serve to raise lowered sheet corners back to the level of the conveying plane 5 as the printed sheets 4 pass by and could therefore also be referred to as straightening wedges. The separating wedges 13 extend through the tapers 12 of the drive shaft 10.

[0026] The separating wedges 13 are each fork-shaped, and a conveyor belt 14 is arranged between the two fork arms of the respective separating wedge 13. The parallel conveyor belts 14 convey the printed sheet 4 delivered by the chain conveyor 2. List of reference symbols 1 print head 2 chain conveyors 3 supporting segment 4 printed sheets 5 conveyor level 6 Deepening 7 Separating element 8 Element section 9 Sheet feed direction 10 Drive shaft 11 Guide disc 12 Rejuvenation 13 Separating wedge 14 Conveyor belt 15 Sheet delivery area 16 Sheet transfer area 17 Overhang 18 Wave 19 Engine QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2017 110 300 A1

[0003] DE 10 2019 209 125 A1

[0004] DE 10 2016 204 215 A1

[0005] DE 10 2015 203 424 A1

[0005] DE 10 2019 211 750 A1

[0005]

Claims

[1] Sheet transport device of a digital printing machine, comprising a chain conveyor (2) with support segments (3) for carrying printed sheets (4), wherein the support segments (3) form a conveying plane (5) and have recesses (6) in which at least one circumferential separating element (7) for separating the printed sheets (4) from the conveying plane (5) is arranged, the separating element (7) is annular and has a linear element section (8) which runs in a sheet conveying direction (9), the separating element (7) is narrower than the support segments (3) transversely to the sheet conveying direction (9), and the element section (8) projects beyond the support segments (3) in the sheet conveying direction (9), characterized by , that an annular movement path of the support segments (3) lies completely within an annular movement path of the separating element (7). [2] Sheet transport device according to claim 1, characterized bythat the separating element (7) and at least one further such separating element (7) are arranged circumferentially parallel to one another. [3] Sheet transport device according to claim 2, characterized by that a common drive shaft (10) is provided for driving the separating elements (7). [4] Sheet transport device according to claim 3, characterized by that guide discs (11) are arranged on the drive shaft (10), on which the separating elements (7) run. [5] Sheet transport device according to claim 4, characterized by that the guide discs (11) are crowned. [6] Sheet transport device according to claim 4, characterized by that separating wedges (13) are arranged between the guide discs (11). [7] Sheet transport device according to claim 6, characterized by that conveyor belts (14) are integrated into the separating wedges (13). [8] Sheet transport device according to one of claims 1 to 7, characterized bythat the element section (8) of the or each separating element (7) is flush with the conveying plane (5). [9] Sheet transport device according to one of claims 1 to 7, characterized by that the or each separating element (7) is designed as a band, rope, belt or chain.

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