Printing press

Abstract

The invention relates to a printing press comprising a sheet collector (2) having two stack positions (a, b) for a stack of good sheets and a stack of waste sheets. In front of each stack position (a, b) on the sheet flow upstream a own powder nozzle device (3, 4) is provided. The two powder nozzle devices (3, 4) are connected to a common powder supply device (7).

Description

Technical Field

[0001] The present invention relates to a printing press comprising a sheet collector having two stacking positions for stacking qualified sheets and waste sheets, respectively. Background Technology

[0002] Such printing presses are used, for example, to print pages made of paper or cardboard using offset printing.

[0003] For example, such a printing press is described in DE102015218131B4. Summary of the Invention

[0004] The objective of this invention is to provide another printing press of the type described above.

[0005] This task is accomplished by a printing press comprising a sheet collector having two stacking positions for stacking qualified sheets and stacking waste sheets, characterized in that each stacking position is provided upstream of the sheet flow with its own powder nozzle device and the two powder nozzle devices are connected to a common powder supply device.

[0006] One advantage of the printing press of the present invention is that it can operate in multiple modes in which the stacking of qualified sheets and the stacking of waste sheets occupy different stacking positions and respectively use powder nozzle devices.

[0007] Provided that they are not technically mutually exclusive, the following extension solutions can be implemented individually or in any combination.

[0008] A switching device may be provided to switch from a mode in which powder is supplied to one powder nozzle device via a common powder supply device to a mode in which powder is supplied to another powder nozzle device via a common powder supply device.

[0009] The switching device may include a powder deflector.

[0010] The powder deflector can be constructed as a baffle or valve with two powder guiding surfaces.

[0011] The switching device may include two powder metering devices, each with its own drive mechanism.

[0012] The powder metering device can be configured as a metering roller and the drive device can be configured as an electric motor.

[0013] The switching device may include a valve device for controlling the air-powder mixture.

[0014] The valve device may have at least one shut-off valve in at least one pipeline between the common powder supply device and a powder nozzle device, and at least one shut-off valve in at least one pipeline between the common powder supply device and another powder nozzle device.

[0015] A common powder supply device can be arranged between two stack locations.

[0016] A common powder supply device can be arranged between two powder nozzle devices.

[0017] The two powder nozzle devices can be arranged at a distance from each other, which is at least one time and at most four times the maximum length of the printed page that the printing press can handle.

[0018] The common powder supply device may include a storage container having a common powder reserve for two powder nozzle devices.

[0019] A common powder supply device may include two injectors for mixing air with powder, one injector being connected to a powder nozzle device and the other injector being connected to another powder nozzle device. Attached Figure Description

[0020] Further extensions can be derived from the following description of the embodiments and related figures. The figures are as follows.

[0021] Figure 1 A schematic diagram of a sheet collector with two stacked sheets and an associated powder nozzle device is shown.

[0022] Figure 2 A first variant of the powder supply device is shown. Figure 1 The two powder nozzle devices are connected to the powder supply device.

[0023] Figure 3 A second variant of the powder supply device is shown. Figure 1 The two powder nozzle devices are connected to the powder supply device.

[0024] Figures 4 to 7 This illustrates a third variant of the powder supply device and different operating modes of the sheet collector. Figure 1 The two powder nozzle devices are connected to the powder supply device.

[0025] Figure 8 Showing the control Figure 1 Flowchart of the powder nozzle device. Detailed Implementation

[0026] exist Figure 1The diagram shows a printing press 1 for offset printing, which includes a sheet collector 2 comprising a first stacking position a with a first sheet stack A and a second stacking position b upstream thereon with a second sheet stack B. Printed sheets of nominal length f are conveyed to and placed on the sheet stacks A and B along the sheet travel direction BLR. A first powder nozzle device 3 is provided for powdering the printed sheets placed on the first sheet stack A, and a second powder nozzle device 4 is provided for powdering the printed sheets placed on the second sheet stack B. The powder nozzle devices 3 and 4 are configured as spray bars. A distance PA exists between the two powder nozzle devices 3 and 4 in the sheet travel direction BLR, the distance corresponding to at least one, at most four, and preferably two times the maximum nominal length f that the printing press 1 can handle.

[0027] Powder nozzle devices 3 and 4 are connected to powder supply device 7 via pipes 5 and 6, and the powder supply device contains storage container 8 with powder reserve 9.

[0028] exist Figure 2 In the first variant shown, a powder metering device 10 is provided below the storage container 8, into which powder falls from the outlet 11 of the storage container 8. The powder metering device 10 has a metering roller 12 and a drive device 13, such as an electric motor, for rotating the metering roller 12. The rotation of the metering roller 12 is indicated by arrows in the figure. The powder falling from the storage container 8 lands on the rotating metering roller 12 and is metered according to a set rotational speed. The rotational speed of the metering roller 12 is set by correspondingly controlling the drive device 13.

[0029] The metered powder falls from the outlet 14 of the powder metering device 10. Below the powder metering device 10 is a powder deflector 15, which is constructed as a baffle 16 with two powder guiding surfaces 17 and 18. The powder guiding surfaces 17 and 18 are located on both sides of the baffle 16 and face away from each other. The powder deflector 15 is centrally located between two injectors 19 and 20, which mix the powder with compressed air from compressed air interfaces 21 and 22 to form an air-powder mixture. The injectors 19 and 20 can also be more generally referred to as mixing chambers.

[0030] The powder diverter 15 can be selectively switched to a first switching position, in which it guides powder from the powder metering device 10 to one of the injectors 19, or switched to a second switching position, in which the powder diverter 15 guides the powder impacted thereon to another injector 20. To switch the powder diverter 15, a baffle 16 is oscillating about a hinge 24 via an actuator 23. The hinge 24 is located at the lower end of the baffle 16 and is situated on a vertical axis of symmetry along with the metering roller 12 and the storage container 8. In both switching positions, the baffle 16 is tilted upwards at an acute angle (with a negative or positive sign) relative to this axis of symmetry; in one switching position (shown in the figure), it tilts towards one of the injectors 20, and in the other switching position (not shown in the figure), it tilts towards the other injector 19.

[0031] Distributors 25 and 26 are connected downstream of the injectors 19 and 20. Each distributor has an inlet and multiple outlets and distributes the air-powder mixture formed in the respective injectors 19 and 20 to conduits 5 or 6 connected to the outlets. These conduits are constructed, for example, as hoses. Conduits 5 connect distributor 25 to a first powder nozzle assembly 3, wherein each conduit 5 is connected to a different nozzle or nozzle group of the first powder nozzle assembly 3. Conduits 6 connect distributor 26 to a second powder nozzle assembly 4, wherein each conduit 6 is connected to a different nozzle or nozzle group of the second powder nozzle assembly 4.

[0032] The powder deflector 15 constitutes a switching device for alternately activating and deactivating the two powder nozzle devices 3 and 4. In one switching position of this switching device, the baffle 16 is relative to... Figure 2 Tilted to the right, the powder guide surface 17 directs the powder into the injector 19, so only the first powder nozzle assembly 3 is supplied with the air-powder mixture. In another switching position, the baffle 16 is relative to... Figure 2 Tilting to the left, and with the powder guide surface 18 guiding the powder into the injector 20, only the second powder nozzle device 4 is supplied with the air-powder mixture.

[0033] Figure 3 The second variant shown is similar to the previous reference in terms of injectors 19, 20, distributors 25, 26, and pipes 5, 6. Figure 2 The variants described are consistent. Figure 3 One difference between this variant and the previous variant is that the latter has two powder metering devices—namely, a first powder metering device 27 and a second powder metering device 28, each structurally and functionally different from the previous one. Figure 2The powder metering device 10 has a similar structure. Another difference is that the storage container 8 has a first outlet 29 and a second outlet 30 at its bottom. A first powder metering device 27 is arranged below the first outlet 29, and a second powder metering device 28 is arranged below the second outlet 30. Powder from the storage container 8 enters the upper-open first powder metering device 27 through the first outlet 29 by gravity conveying, and enters the upper-open second powder metering device 28 through the second outlet 30.

[0034] By correspondingly driving and controlling the driving devices 39 and 40 of the metering rollers 37 and 38 of the two powder metering devices 27 and 28, in one mode ( Figure 3 In one mode (indicated by a rotating arrow), only the first powder metering device 27 is activated and the second powder metering device 28 is deactivated; in another mode (not shown), the first powder metering device 27 is deactivated and only the second powder metering device 28 is activated. When the respective powder metering devices 27 and 28 are activated, their metering rollers 37 or 38 rotate, thereby metering the powder and conveying it to the downstream injector 19 or 20. When the respective powder metering devices 27 and 28 are deactivated, their metering rollers 37 or 38 do not rotate, therefore no powder is metered and conveyed to the downstream injector 19 or 20.

[0035] The two mutually reversibly driven drive units 39 and 40 of the metering rollers 37 and 38 of the powder metering devices 27 and 28 together constitute a switching device. The switching device has a switching position and another switching position. In the switching position, only the drive unit 39 of the first powder metering device 27 is activated, so only the first powder nozzle device 3 is supplied with air-powder mixture, which is sprayed by the first powder nozzle device 3 onto the printed pages to be placed on the first sheet stack A. In the other switching position, only the drive unit 40 of the second powder metering device 28 is activated, so only the second powder nozzle device 4 is supplied with air-powder mixture, which is sprayed by the second powder nozzle device 4 onto the printed pages to be placed on the second sheet stack B.

[0036] exist Figures 4 to 7 The diagram shows a third variant in which the switching device is a valve assembly having a shut-off valve 31 in each pipe 5 and a shut-off valve 32 in each pipe 6. Figures 4 to 7 For the sake of drawing simplification, only one pipeline 5, 6 and only one shut-off valve 31, 32 are shown respectively. Two switching positions are achieved by mutually reversibly controlling the two sets of shut-off valves 31, 32. In one switching position ( Figure 5 and 6The shut-off valve 31 is closed and the shut-off valve 32 is open, so that the air-powder mixture from the powder supply device 7 reaches only the second powder nozzle device 4 for spraying, and does not reach the first powder nozzle device 3. In another switching position ( Figure 4 and 7 When shut-off valve 31 is open and shut-off valve 32 is closed, the air-powder mixture from the powder supply device 7 reaches only the first powder nozzle device 3 for spraying, without reaching the second powder nozzle device 4. Shut-off valve 31 can be integrated into a valve block with a common actuator, and shut-off valve 32 can be integrated into another valve block with a common actuator, where these two valve blocks together constitute a valve device. However, shut-off valves 31 and 32 can also be configured as remotely controllable solenoid valves.

[0037] In a modified embodiment not shown, the valve assembly consists of only two shut-off valves, one of which is located in compressed air port 21 and the other in compressed air port 22.

[0038] Figures 4 to 7 The specific operating modes of the page collector shown are as follows.

[0039] Figure 4 and 5 A pattern is shown in which the first page stack A is a valid page stack and the second page stack B is a invalid page stack.

[0040] Figure 4 One mode is shown in which qualified sheets GB are powdered via a first powder nozzle device 3 and then placed on a first sheet stack A. Shortly thereafter, as the qualified sheets GB pass a second powder nozzle device 4 along the sheet running direction BLR, the latter is switched off by a switching device. As the qualified sheets GB placed on the first sheet stack A pass the second powder nozzle device 4, the latter neither ejects air nor powder, thus advantageously not affecting the sheet running of the qualified sheets GB.

[0041] Figure 5 One configuration is shown in which waste sheets MB are powdered via a second powder nozzle device 4 and then placed on a second sheet stack B. Shortly thereafter, when the gaps in the sheet flow (which are left between the sorted waste sheets and the continuing qualified sheets) pass through the first powder nozzle device 3, the latter is switched off by a switching device. Since the first powder nozzle device 3 does not spray powder into the gaps, it advantageously avoids the machine from being contaminated by powder and the waste of powder.

[0042] Figure 6 and 7A pattern is shown in which the first page stack A is a waste page stack and the second page stack B is a valid page stack.

[0043] Figure 6 One mode is shown in which qualified sheets GB are powdered via a second powder nozzle device 4 and then placed on a second sheet stack B. In a non-disruptive (no waste) printing run, qualified sheets GB are powdered one after another in the sheet stream via the second powder nozzle device 4 and then placed on the second sheet stack B, while the first powder nozzle device 3 is switched off by a switching device. Since the first powder nozzle device 3 does not eject powder during a non-disruptive printing run, powder contamination and powder waste are advantageously avoided.

[0044] Figure 7 One configuration is shown in which waste sheets MB are powdered via a first powder nozzle device 3 and then placed on a first sheet stack A. Shortly thereafter, when the waste sheets MB placed on the first sheet stack A pass through a second powder nozzle device 4, the latter is switched off by a switching device. If the waste sheets MB to be sorted have already been powdered via the second powder nozzle device 4, there is a risk that a significant portion of the powder applied via the second powder nozzle device 4 may detach from the waste sheets MB again during the long-distance transport from the waste sheets MB to the first sheet stack A, leading to machine contamination. Furthermore, the subsequent lack of powder on the waste sheets MB in the first sheet stack A causes the waste sheets MB to adhere to the waste sheets placed on top of them within the first sheet stack A. This danger can be eliminated by first applying powder to the waste sheet MB to be sorted through the first powder nozzle device 3. This occurs both spatially and temporally before the waste sheet MB is placed tightly on the first sheet stack A. Therefore, almost no powder can fall off the waste sheet MB until it is placed on the first sheet stack A.

[0045] It goes without saying that, regarding Figure 5 and Figure 7 The pattern described using the example of a single invalid MB in a page stream is similarly applied when multiple consecutive invalid MBs appear in the page stream.

[0046] It is equally self-evident that, regarding Figures 4 to 7 The switching device illustrated as an example of a valve device (stop valve 31, 32) can also be executed using a switching device constructed as a powder diverter 15 or a metering device pair (powder metering device 27, 28).

[0047] exist Figure 8 In the following text, the process is simplified again.

[0048] A program runs in the electronic control unit 33 of the printing press that determines whether the respective printed sheets 34 (qualified sheets GB, defective sheets MB) are placed on the first sheet stack A or the second sheet stack B. If the printed sheets 34 are placed on the first sheet stack A, the first powder nozzle device 3 is activated and the second powder nozzle device 4 is deactivated in program step 35. Conversely, if the printed sheets 34 should be placed on the second sheet stack B, the first powder nozzle device 3 is deactivated and the second powder nozzle device 4 is activated in program step 36.

[0049] List of reference numerals in the attached diagram: 1 Printing press 2-page collector 3 First powder nozzle device 4. Second powder nozzle device 5 pipes 6 pipes 7 Powder supply device 8 storage containers 9 Powder Reserves 10 Powder Metering Device 11 Exports 12 metering rollers 13 drive units 14 Exports 15 Powder Steering Gear 16 baffles 17 Powder Guide Surface 18 Powder Guide Surface 19 jets 20 injectors 21 Compressed air interface 22 Compressed Air Interface 23 Implementing agencies 24 hinges 25 Distributor 26 Distributor 27 First Powder Metering Device 28 Second powder metering device 29 First Exit 30 Second Exit 31 shut-off valve 32 shut-off valve 33 Control Device 34 printed pages 35 Procedure Steps 36 program steps 37 Metering Rollers 38 metering rollers 39 drive unit 40 drive unit Page A, stacked pile Page B, second page, stacked pile GB Compliance Page MB waste pages PA distance a First stack position b. Second stack position f is the specified length.

Claims

1. A printing press comprising a sheet collector (2) having two stacking positions (a, b) for stacking qualified sheets and stacking waste sheets, characterized in that, Each stack location (a, b) upstream of the sheet flow is equipped with its own powder nozzle device (3, 4); and These two powder nozzle devices (3, 4) are connected to a common powder supply device (7).

2. The printing press according to claim 1, characterized in that, There is a switching device for switching from a mode in which powder is supplied to one powder nozzle device (3) via a common powder supply device (7) to a mode in which powder is supplied to another powder nozzle device (4) via a common powder supply device (7).

3. The printing press according to claim 2, characterized in that, The switching device has a powder deflector (15).

4. The printing press according to claim 3, characterized in that, The powder deflector (15) is constructed as a baffle (16) having two powder guiding surfaces (17, 18).

5. The printing press according to claim 2, characterized in that, The switching device includes two powder metering devices (27, 28) each with its own drive unit (39, 40).

6. The printing press according to claim 5, characterized in that, The powder metering device (27, 28) is configured as a metering roller (37, 38) and the drive device (39, 40) is configured as an electric motor.

7. The printing press according to claim 2, characterized in that, The switching device includes a valve device for controlling the air-powder mixture.

8. The printing press according to claim 7, characterized in that, The valve device includes at least one shut-off valve (31) in at least one line (5) between the common powder supply device (7) and a powder nozzle device (3), and at least one shut-off valve (32) in at least one line (6) between the common powder supply device (7) and another powder nozzle device (4).

9. The printing press according to any one of claims 1 to 8, characterized in that, The common powder supply device (7) is arranged between the two stacking positions (a, b).

10. The printing press according to any one of claims 1 to 8, characterized in that, The two powder nozzle devices (3, 4) are arranged at a distance (PA) corresponding to at least one and at most four times the specification length (f) of the largest specification of the printable sheet (34) that can be handled in the printing press.

11. The printing press according to any one of claims 1 to 8, characterized in that, The common powder supply device (7) includes a storage container (8) having a common powder reserve (9) for the two powder nozzle devices (3, 4).

12. The printing press according to any one of claims 1 to 8, characterized in that, The common powder supply device (7) includes two injectors (19, 20) for mixing air with powder, one injector (19) being connected to a powder nozzle device (3) and the other injector (20) being connected to another powder nozzle device (4).

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