Bogenausleger

Abstract

A sheet delivery unit of a printing press comprises a delivery unit housing (6) with an opening (7) and an associated roller shutter (8). During printing, a lower part of the opening (7) is closed by the roller shutter (8) in a first position, and an upper part of the opening (7) is closed by a curtain of blown air (9) from a doctor blade (13). When a stack of sheets is transported by a forklift truck through the opening (7) and out of the delivery unit housing (6), the roller shutter (8) is in a second position below a travel path (21) for the forklift truck.

Description

[0001] The present invention relates to a sheet-fed boom of a printing press, comprising a boom housing with an opening and an associated roller blind.

[0002] These sheet delivery units are used to place the sheets printed in the printing press onto a stack. To prevent the sheets from sticking together in the stack, they are dusted with powder before being placed. It is unavoidable that a mist of powder will spread inside the delivery unit housing.

[0003] For example, German patent DE 10 2023 100 461 A1 describes a sheet feeder in which, during printing, the opening is essentially completely closed by the roller blind, which has a filter. The filter prevents the powder from escaping through the opening into the area surrounding the sheet feeder and contaminating it.

[0004] The purpose of the invention is to create an additional arched boom.

[0005] The problem is solved by a sheet boom of a printing press, comprising a boom housing with an opening and an associated roller blind, characterized in that during printing operation a lower part of the opening is closed by the roller blind in a first position and an upper part of the opening by a curtain of blown air ejected from a doctor blade, and that when a stack of sheets is transported through the opening out of the boom housing by a forklift truck, the roller blind is in a second position below a travel path for the forklift truck.

[0006] An advantage of the bow-shaped boom according to the invention is that it harmonizes both requirements: It ensures both effective sealing against powder escaping from the boom and good accessibility of the boom interior for the forklift. The bow-shaped boom according to the invention is also advantageous when used in a printing press without powder dusting, as it ensures sealing against the escape of contaminated air, e.g., process air from dryers.

[0007] The following training courses are available individually or in any combination: The roller blind may have a spool that is arranged in a first pit.

[0008] The pit may be assigned a cover which can be adjusted into a cover position to cover the pit and which, in the cover position, can form part of the driving path.

[0009] The cover can be designed as a flap.

[0010] A suction device may be arranged below the travel path.

[0011] The suction device can be located in a second pit.

[0012] The second pit can be covered by a suction-air-permeable cover, which can form part of the driving path.

[0013] The air-permeable cover can be a grating or a perforated plate.

[0014] The air squeegee can be positioned above the opening or at the upper edge of the opening and expel the curtain of blown air vertically downwards or diagonally downwards.

[0015] Further information can also be obtained from the following description of an exemplary embodiment and the associated drawing.

[0016] It shows: Fig. 1. A three-dimensional representation of an arched extension, Fig. 2 the arched extension with a closed roller blind, in a sectional view according to the one in Fig. 1 specified section line II-II, and Fig. 3 the arched extension with the roller blind open.

[0017] In the delivery unit of an offset printing press, sheets are transported in a transport direction 1 to a stack of sheets 2 and placed thereon one after the other. The stack of sheets 2 is located on a pallet 3, which rests on a support plate 4 suspended by tension chains 5. The support plate 4 and the tension chains 5 are components of a stack lifting device. The stack lifting device is located in a delivery unit housing 6, which has an opening 7 on the right (drive side of the printing press), on the left (operator side), and at the front (front side) with respect to the transport direction 1.

[0018] The technical measures described below using the example of the front opening 7 can also be provided for the right or left opening 7 instead or additionally.

[0019] Opening 7 is in printing mode ( Fig. 1 and Fig. 2) The lower half is mechanically closed with a roller blind 8, and the upper half is pneumatically closed with an air curtain 9. Vertical linear guides 11 for guiding a carriage 12, to which the roller blind 6 is attached, are arranged on columns 10 of the cantilever housing 6. The linear guides 11 can be grooves or rails.

[0020] The air curtain 9 is ejected downwards from an air squeegee 13, and its blowing air flows downwards along the inside of the roller blind 6. The blowing air, laden with entrained powder, is drawn in by a suction device 14 and conveyed out of the sheet feeder, e.g., to a filter. The air squeegee 13 is located at the upper edge of the opening 7 and can be designed as a blow tube with a slot nozzle or with a row of nozzles. During printing, the air curtain 9, which extends essentially across the entire width of the opening 7, prevents stray dusting powder from escaping from the feeder housing 6 through the opening 7 into the surrounding environment and allows the operator a clear view into the sheet feeder. The air curtain 9 can be temporarily deactivated during printing to allow access to the sheet stack 2, for example, to remove a sample sheet.

[0021] A spool 15 for the roller shutter 8 is arranged in a first pit 16 below a base 17 on which the boom housing 6 stands. The suction device 14 is arranged in a second pit 18 in the base 17. The two pits 16 and 18 are arranged within the mounting area of ​​the arched boom, with the second pit 18 being located further inside the boom than the first pit 16. A flap 19 serves as a cover for the first pit 16. When the roller shutter 8 is raised, the flap is folded up or opened during printing operation, and when the roller shutter 8 is completely wound onto the spool 15 ( Fig. 3) is folded down or closed during the removal of the stack of bows 2 from the boom housing 6.

[0022] The suction device 14 can be deactivated during stack removal to save energy and reduce noise. Likewise, the air squeegee 13 can be deactivated to prevent the top sheets of the removed stack from shifting due to blowing air.

[0023] During stack removal, which takes place outside of the printing process, the stack lifting device is emptied by using a forklift, for example a pallet truck, to move the pallet 3 with the stack of sheets 2 through the opening 7 out of the boom housing 6. The flap 19 and a grating 20 covering the second pit 18 are sturdy enough to allow the forklift to drive over them, thus forming a travel path 21 for the forklift. The forklift can therefore roll over the two pits 16 and 18 without obstruction. During stack removal, often also referred to as stack change, a new, empty pallet 3 is placed on the support plate 4 to receive the printed sheets for the next printing job.

[0024] The grating 20 forms a cover for the second pit 18, which allows the air drawn in by the suction device 14 during pressure operation to pass through. Modifications may include:

[0025] The two pits 16, 18, which in the example shown are separated by a partition wall, can be combined into a single large pit by removing the partition wall.

[0026] In this case, a hinged grating can be used to cover the large pit instead of the two covers (flap 19, grating 20). A perforated plate or a hinged perforated plate can be used instead of either grating 20 or the hinged grating. Reference symbol list 1. Transport direction 2 stacks of sheets 3 pallets 4 support plate 5 pull chain 6 cantilever housings 7 Opening 8 roller blinds 9 Air curtain 10th pillar 11 Linear guide 12 sleds 13 air rakes 14 Suction unit 15 coils 16 pit 17 Floor 18 pit 19th flap 20 grating 21 Route

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