EP2520431B1 - Method for cleaning colour decks in offset printers and offset printer - Google Patents

Description

Offset printing machines, be it so-called web presses, in which a paper web is printed, or sheetfed presses in which already cut sheets are transported through the machine and printed on one or both sides color, have several printing units, each printing unit in turn has an inking and the respective inking unit again a paint tray extending across the width of the print format. Which in turn is due to the so-called ink ductor, which removes the ink to be printed from the ink tray and further promotes to the other rollers of the inking unit. As far as it is offset printing machines with so-called short inking, the liquid anilox used for this purpose is taken up in a chambered doctor blade, which rests against a so-called anilox roller, which occupies a similar function as the ductor in this case.

Between different print jobs, it may be necessary to change the ink in the respective inking unit or the ink tray, either because the next job is printed with a different set of colors, or because the color in their properties z. B. Pollution degree etc. no longer meets the requirements. In general, therefore, not only the ink pans are emptied when changing jobs, but washed the entire inking and also washed the blanket on the blanket cylinder and the impression cylinder, so all the parts that have taken on printing color.

Washing devices for offset printing machines are described, for example, in the following documents: US 8056476 B2 . US8033219 B2 . US 7677174 B2 . US 7533609 B2 and US 7373882 B2 ,

A job change is therefore not only connected with downtime for the printing press because of the above-mentioned cleaning processes, but the cleaning processes contribute significantly to the downtimes.

There has been no lack of ideas and attempts to reduce set-up time for offset printing presses, with particular emphasis on shortening wash times. One of these proposals was to run the washing program for the various printing units of the printing press all at the same time. This is the usual way in which the washing processes are controlled, namely in parallel. It has also been proposed to perform washing operations when the printing plates are changed for the next job. For this purpose, however, it is then necessary, for example, to decouple the impression cylinder from the gear train for the individual cylinders of the printing press in order to be able to drive or move it separately for the plate change while the washing process is running for the blanket cylinder in which it is subject to a different movement.

In the EP 0654350 B 1 is proposed to make the wash sequence programs variable and to make, for example, the time course, operating parameters of the printing press or the degree of contamination. For this purpose, the EP 0654350 B1 to run the wash cycle programs fully automatically to completely remove the influence of an operator.

With such approaches, in which it is attempted to optimize the set-up time only by an isolated influence of the washing program or the washing times themselves but one jumped too short. Because there are a variety of other activities, including manual activities that a printer has to make on a printing press when changing jobs. This includes, among other things, the emptying of the paint pans, which is done manually, by so-called "filling out". Here, an inserted into the ink tray or ink fountain sheet is removed with the ink residue and the so-called ink jaws are cleaned, these are parts that limit the color box laterally and seal against the ink fountain roller. This also includes reinserting a fresh film and re-filling new paint in the paint tray either also manually with the paint spatula or by inserting a corresponding new ink cartridge in an automatic refill system that moves back and forth over the ink fountain and this filled and optionally replenished.

The filling of the old paint and the re-filling of the new paint naturally occurs when only a single printer operates the machine, sequentially. The invention has therefore set itself the goal, in such a case d. H. in a method for cleaning inking units in offset printing machines, in which the ink pans of the individual inking units of the printing units are sequentially emptied one after the other and then refilled with ink to reduce set-up times when changing jobs.

This object is achieved in that immediately after the emptying of the first ink tray of the washing process for the associated inking is started before the other ink pans are emptied, and each time after emptying another of the other ink pans the washing process for the respective other inking is started and that the refilling of the first ink tray is started while still washing operations for one or more of the further inking units are underway.

With this measure, the entire process, namely the manual activities of the printer during the job change along with the washing sequences is optimized. Because already begin the washing operations in individual inking units, while the remaining inking units are not emptied or filled out, these sequences are also terminated earlier, so that the printer can start there again with the refilling, while washing programs for other inking units are still running , The total time of the process from the start of the emptying of the first ink fountain or paint tray to the completion of the refilling of the last inking unit is therefore even shorter, compared with the case of washing only after all the ink pans have been emptied, even if all the washing operations in all Run inking at the same time.

The cleaning program for the blanket or the printing cylinder of the associated printing unit can already be started while the emptying of the first ink tray is started.

All of the inking units of the printing press can also be driven together via the main drive of the printing press and be in motion while the printer is working on emptying the ink pans. A separate coupling and uncoupling of individual inking units especially for the cleaning process is not required.

Especially useful for handling and operation, it is when the end of the emptying of the ink pan is either automatically detected and used to start the wash program for the associated inking, or if the respective inking unit or printing unit within reach of the printer, which emptied there the paint tray , a switch or button is attached, with which this can then start the washing sequence without having to go to the control panel of the printing press. For example, this can be done by a sensor that detects the folding of the ink tray of the ink fountain roller, so the movement that is performed by the printer at the end of the emptying. Such a sensor, pushbutton or switch not only serves the convenience of the printer, but reduces the set-up time, as this does not have to interrupt his work to start the washing sequence on the control panel, but immediately on the next printing unit with the emptying of the ink tray can begin. Furthermore, the ink pans, inking units or printing units of the printing machine can be associated with display devices which are connected to the controller for the inking unit washing and the printer to indicate the order of emptying of the ink fountain by corresponding optical signals.

• Figur 1 ist die Prinzipskizze einer Bogenoffsetdruckmaschine mit vier Druckwerken.
• Figur 2 ist die Prinzipskizze eines Farbwerks der Bogenoffsetdruckmaschine aus Figur 1, modifiziert gemäß der vorliegenden Erfindung.
• Figur 3 zeigt Ablaufdiagramme, die den zeitlichen Ablauf der Arbeiten an einem Farbwerk während eines Auftragswechsels wiedergeben.

Further advantages of the invention will become apparent from the dependent claims and are explained in more detail using an exemplary embodiment with reference to the accompanying figures of the drawings.

• FIG. 1 is the schematic diagram of a sheetfed offset press with four printing units.
• FIG. 2 is the schematic diagram of an inking unit of the sheetfed offset press FIG. 1 Modified according to the present invention.
• FIG. 3 shows flowcharts that show the timing of the work on an inking unit during a job change.

FIG. 1 shows an offset printing machine 1 in a row construction with a feeder 2, in which the unprinted paper stack 3 is located, and four printing units 7a - d for the four primary colors black, yellow, magenta and cyan. Between the printing units, the sheets to be printed are conveyed by transfer drums 12a-c to the respective counter-pressure cylinders 4b-d of the printing units. On the fourth printing unit 7d follows the boom 9 of the printing press. In it gripper bars 11 run around by means of a chain guide. These gripper bars 11 take over the printed sheet and lead it to the sheet stack 10, where it is stored.

Each of the four printing units 7a-d has an impression cylinder 4a, a blanket cylinder 5a and a printing form cylinder 6a, on which the respective printing plate is mounted. The printing plates are dyed by inking units 8a-d, one of which will be described in more detail below.

The functions in the printing units 7a-d, the feeder 2 and the feeder 9 are operated, controlled and monitored by a machine control 56.

This in FIG. 2 shown inking unit has a paint tray 13, a ductor roller 14, four inking rollers 28, 29, 30 and 31, with which the printing plate is inked on the cylinder 6a, and a number of other rollers 15 to 27, of which the color of the ductor 14 removed, distributed and triturated and then fed to the applicator rolls. With 15 of the clockwise between the ductor 14 and the roller 21 oscillating color lifter is designated. The rollers 21, 22, 23 and 24 are traversing distributor rollers, the drivers 23 and 24 being cooled. The ductor 15 and the rollers 16, 17, 18, 19, 20 are provided as well as the four inking rollers 28 to 31 with a rubber jacket, while the bridge roller 32, between the Dampening roller 37 and the first inking roller 28 is arranged, as well as the rollers 27, 26 and 25 are steel rollers.

For washing the inking unit, a trough 42 with a washing blade 41 is provided, which can be placed against the roller 24. Furthermore, spray pipes 43 and 44 are provided, of which can be sprayed in the course of issued by a control commands to two valves 53 and 54 and wash liquids in the inking unit.

The ink tray 13 is symbolized by the arrow 51 pivotable about an axis 50 and can be moved away so after their emptying of ductor 14 and locked to a stop 52. At this stop, a limit switch 57 is attached, recognized by the completed Abstellbewegung the paint tray and is signaled to the part 55 of the controller 56, which is responsible for the washing operations.

In the case of a job change, the printer has hitherto proceeded according to the prior art as follows ( FIG. 3 : above): It is assumed that three of the four inking units must be cleaned, while in the fourth inking unit z. B. the color black can remain.

The washing of the blanket and possibly printing cylinders starts in all printing units that were used at the end of the order. This is symbolized by the bar labeled GTW. Simultaneously with the start of the washing of these cylinders, the printer begins to paint the ink from the ink tray of the first printing unit 1. The time required for this is indicated by the bar labeled DW 1. Then he folds the ink tray off the ductor and goes to the next printing unit, where he continues with the emptying there. This is symbolized by the bar labeled DW 2. Thereafter, the same process for the printing unit 3 (DW 3).

Then the printer goes to the control panel and starts the washing operations for the inking units in the printing units 1 to 3, which then all run at the same time. This is symbolized by the three superimposed bars, which are each labeled FW 1 to FW 3.

As soon as these washing processes have been completed, the printer refills ink in the printing units 1 to 3 (bars DW 1 to DW 3). It takes about 3 minutes for the inking unit wash FW to wait for the printer before it can start refilling the ink pans.

The sequence according to the invention is then in the FIG. 3 in the lower part: Here too the washing of the blanket and other cylinders outside of the inking unit starts immediately after the previous print job is finished. Again, the printer starts filling out the ink from the printing units 1 to 3 one after the other (bars DW 1 to DW 3) ,

However, as soon as he has emptied the first ink tray and is folded away from the ductor, the Abklappbewegung the switch 57 is actuated, is reported by the controller 55 for the inking unit that the ink tray 13 is empty. This control part 55 in the control console 56 of the printing press then starts, as soon as the washing of the blanket cylinder and printing cylinder is completed to start the Farbwerkswaschvorgang FW 1 for the first inking unit. While this process, designated FW 1, is still in progress, the printer empties the troughs of the inking units in the further printing units 2 to 3, and the inking system washing sequence for the associated inking unit is started by the controller every time the respective tray 13 is folded down.

As soon as the washing sequence FW 1 for the first inking unit has ended, the printer can immediately start refilling the first printing unit DW 1 and then also the remaining trays for the inking units in the printing units 2 and 3 as soon as the washing operation is completed in the respective inking unit ,

Overall, therefore, the set-up time required for cleaning the inking units of previously 12 minutes shorten as shown in the diagram after FIG. 3 below given to about 9 minutes, although the washing operations for the inking units in the printing units 1 to 3 are not performed in parallel, but partly overlapping sequentially, basically by a shortened waiting time for the printer. In addition, it is not necessary, the gear train the printing press, from which the various cylinders are driven, including blanket cylinder, plate cylinder and inking unit, separate. All washings can be carried out while the machine is kept moving at the speed that is reduced for washing.

The invention has been described above with reference to a printing press with a conventional inking unit with trough and ductor. However, the described processes can be realized in the same way also in offset printing machines with so-called short inking units. In this case, a chamber doctor blade is used instead of the ink tray, which is not folded for cleaning by the non-existent there ductor, but by the anilox roller to which the chamber doctor blade otherwise applied during printing.

LIST OF REFERENCE NUMBERS

1

Offset

2

investor

3

stack of paper

4a - d

Impression cylinder

5a - d

Blanket cylinder

6a - d

Plate cylinder

7a - d

printing unit

8a-d

inking

9

boom

10

sheet pile

11

gripper

12

Transfer tert drums

13

paint tray

14

Ductor roller / Farbduktor

15 to 27

roller

28 to 31

Inking roller

32

bridge roller

37

Dampener roller

41

wash-up blades

42

tub

43, 44

lance

50

axis

51

arrow

52

attack

53, 54

Valve

55

control part

56

machine control

57

limit switch

Claims (10)

1. Method for cleaning inking units in offset printing presses in which the ink fountains (13) of the individual inking units (8a-d) of the printing units (7a-d) are emptied, washed, and subsequently refilled with ink,
   characterized in
   that the ink fountains (13) of the individual inking units are emptied sequentially one after the other, that immediately after the first ink fountain (13) has been emptied, the washing operation for the associated inking unit is started even before the remaining ink fountains are empty, and the washing operation for each further inking unit is started as soon as the respective ink fountain is empty, and that the refilling of the first ink fountain (13) is started while washing operations for one or more of the further inking units are still going on.
2. Method according to Claim 1,
   wherein the refilling of the next one of the further ink fountains is always started as soon as the washing program for the respective associated inking unit is completed.
3. Method according to Claim 1,
   wherein even while the first ink fountain is being emptied, a cleaning program for the blanket or the impression cylinder of the associated printing unit is started.
4. Method according to Claim 1,
   wherein the inking units of the printing press are jointly driven by the main drive of the printing press and are in motion during the emptying of at least one of the further ink fountains.
5. Method according to Claim 1,
   wherein having been emptied, the respective ink fountain (13) is moved away from the ink fountain roller (14) and a signal is generated in the course of the movement to start the washing operation for the associated inking unit.
6. Method according to Claim 1,
   wherein the respective ink fountain is a chambered doctor blade that, having been emptied, is moved away from the associated screen roller.
7. Method according to any one of Claims 1 to 6,
   wherein either sensors (57) for detecting the respective moving away or the fill level of the fountain (13) are associated with the ink fountains (13) or switches, push-buttons etc. are arranged on the printing units (7a-d), the sensors, switches, push-buttons etc. generating corresponding signals that are associated with a control for the washing operation in such a way that a washing program for the associated inking unit is started automatically by the respective moving away, due to the fill level, or by the operation of the respective switch or push-button.
8. Method according to Claim 7,
   wherein the ink fountains (13) or chambered doctor blades can be swung away.
9. Method according to Claim 7,
   wherein the control for controlling the washing operations is part (55) of the machine control (56) of the printing press (1).
10. Method according to Claim 7,
    wherein display devices that are connected to the control for the washing of the inking units are associated with the ink fountains, inking units, or printing units and are actuated in accordance with the sequence of the emptying of the inking unit fountains.

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