EP2946927B1 - Method for operating a printing press - Google Patents

Description

The present invention relates to a method for operating a printing press.

When printing a print job, the press is stopped for various reasons (e.g., blanket wash, sheet stack change). During these interruptions, the color profile on the rollers is undesirably equalized and the color reacts with the air or loses moisture. At restart, this then leads to so-called start-up waste, that is, faulty printed sheets that can not be sold. In order to prevent the undesired equalization of the color profile, mechanical solutions (for example ink fountain roller separation during the printing interruption, stopping of the distributor roller traversing movement during the printing interruption) are used. These have the disadvantage that on the one hand they are technically complicated, on the other hand, e.g. in the case of UV inks lead to ringing in the inking unit. Likewise, the evaporated moisture is not replaced, the color is not renewed.

In DE4312229C2 a method is described, with which a print job change a close to the color distribution is achieved. During the print job change, a printing plate of the previous print job is changed to a printing plate of the subsequent print job.

The invention has for its object to provide a further method for operating a printing press.

This object is achieved by a method having the features of claim 1.

In the method according to the invention for operating a printing press, a color profile in an inking unit is at least partially degraded in an inking unit by interrupting the ink supply and printing a specific number of sheets with interrupted ink supply, in a first process step in a print interruption within a print job other than an emergency stopper while a cylinder performs a certain number of revolutions, and in a second process step, the color profile is completely rebuilt by resuming the ink supply and performing a paint run without printing the same predetermined number of sheets, with the cylinder performing the same specified number of revolutions.

By the cylinder is meant a forme cylinder, a blanket cylinder (offset cylinder), or an impression cylinder of the printing unit to which the inking unit belongs, but not a roller of the inking unit or a possibly associated dampening unit.

The specific number of sheets can z. B. 15, so that in the first step, 15 sheets are printed without supplying ink from a color box before the print off occurs. When printing off, the blanket cylinder is moved away from the impression cylinder.

The entry of ink from the ink fountain in the second process step is completed after the specified number of "imaginary" sheets - 15 sheets in the example given - have been fed through the press. By the imaginary sheets are meant sheets which, due to the cylinder revolutions of one or more impression cylinders and one or more transport cylinders, could have been conveyed if a sheet feeder were active in the ink feed and supplied the cylinders with the sheets, which was not the case.

The specific number of revolutions of the cylinder is correlated with the determined number of arcs and z. B. same with the latter. In the example given, the specific number of revolutions of the cylinder is 15. In the case that the cylinder is an impression cylinder, the correlation between on the one hand conveying the sheet in color profile degradation or conveying the imaginary sheet (non-conveying of sheets) at the ink inlet On the other hand, the cylinder revolutions even more clearly because the impression cylinder is known to be a cylinder for transporting sheets.

An advantage of the method according to the invention is that the problems described at the outset can thus be solved and start-up waste can be reduced.

In a further development, the printing interruption is a stop for color measurement or adjustment when setting up or stopping for washing a blanket or stopping due to waste in the course of printing or stopping after reaching an OK sheet when setting up and before starting the printing or stopping at a sheet pile change or a predictable print break.

When setting up the machine before printing, print quality parameters, e.g. B. the paint, measured on the sheet and corrected based on the result of the measurement settings, z. B. Settings of the metering device on the ink fountain. To avoid waste, it may be convenient to temporarily print during the measurement and / or readjustment.

During the print job, intermediate cleaning of the blanket cylinder may be required, eg. B. if it has accumulated much paper dust from the bow. These intermediate cleanings can be carried out regularly or as needed. It can happen that waste material is created and recognized during the ongoing production run. Such waste can z. B. caused by disturbances in the dampening unit. To eliminate the interference, a print interruption is required, for which the printing press is stopped.

When setting up the press for a print job, some sheets of paper waste will inevitably be printed until the first sheet has been printed, the print quality of which is acceptable. This sheet is called OK sheet. After reaching the OK sheet, further setup work may be required before the printing starts. For such setup work, the printing interruption between OK sheet and printing is required.

In a large print job, it may be necessary to supply the sheet feeder of the printing machine with a supply of blank blank sheet and remove printed sheet from the sheet delivery to make room for subsequent. The required stack changes can basically either in non-stop mode or during a print interruption. Only the latter of the two cases requires a print interruption and is therefore relevant in connection with the method according to the invention.

The processing of a print job can extend over several working shifts. The intervening shift change and also rest periods are foreseeable or plannable pressure interruptions with regard to their entry time. In contrast, an emergency stopper is not a predictable or predictable print interruption. The pressure interruption associated with the method according to the invention is a pressure interruption other than an emergency stopper.

In a further development, the movement of a roller is stopped in the first step in order to interrupt the ink supply.

This roller may be an ink fountain roller or a squeegee roller. The lifting roller oscillates periodically between the ink fountain roller and an inking roller - preferably a distributor roller - back and forth to transfer from the former to the latter the color. The squeegee roller alternates with the ink fountain roller and the inking roller in rolling contact. If the roller to be stopped for interrupting the ink supply is a lifting roller, its pendulum motion is stopped. If the roller to be stopped is an ink fountain roller, its rotation is stopped.

In a further development, all color zones of a metering device are closed in the first method step in order to interrupt said ink supply. The metering device is arranged on the ink fountain and comprises a parallel with the ink fountain roller row of metering elements, which can be designed as Dosierexzenter, metering slide, Dosierzungen, or metering. Per color zone a metering element is arranged. By adjusting the respective metering element to the ink fountain roller, an intermediate metering gap is closed, so that through this through the ink fountain roller promote any color out of the ink fountain out can. In order to interrupt the ink feed in the first process step, the dosing gaps in all existing ink zones are completely closed.

In a further development, one or more distributor rollers change continuously during the printing interruption. The single or each distributor roller carries out the reciprocating movement along the roller rotation axis both in the first and in the second method step. A device, for. B. clutch, to take place for the time of the print interruption stopping the traversing movement, whereby the manufacturing cost of the printing press can be reduced.

In a further development, the printed in the first process step certain number of sheets is used as a good sheet. Although these sheets have been printed without ink supply from the ink fountain, their print quality is sufficiently good, so that these sheets are not spoiled sheets and are not rejected.

In a further development is printed before and after the print interruption with one and the same printing plate or printing plate. There is no change of printing plates within the printing interruption. Accordingly, the print interruption is not a print interruption between two different print jobs.

Functionally and structurally advantageous developments will become apparent from the following description of an embodiment and the accompanying drawings.

Figur 1

eine Druckmaschine,

Figur 2

ein Produktionsablaufdiagramm für die Druckmaschine in Figur 1 und

Figur 3

ein Farbprofil im Farbwerk der Druckmaschine in Figur 1.

It shows:

FIG. 1

a printing machine,

FIG. 2

a production flow chart for the press in FIG. 1 and

FIG. 3

a color profile in the inking unit of the printing press in FIG. 1 ,

In FIG. 1 a printing machine for printing sheets is shown in fragmentary form. The detail shows parts of a printing unit for planographic offset printing. A forme cylinder 1 with a printing plate 2 is inked by an inking unit 3. The inking unit 3 comprises an ink fountain 4 with a metering device 5 and an ink fountain roller 6. A lifting roller 7 oscillates from the ink fountain roller 6 to a distributor roller 8 and back. The ink is transferred from the forme cylinder 1 to a blanket cylinder 9 and from there to the sheets. The ink zone openings of the metering device 5, the rotational movement of the ink fountain roller 6 and the oscillating movement of the lifting roller 7 are controlled by a control device 10 according to their programming.

In FIG. 2 a workflow is shown schematically. The printing machine first processes a first print job 11 and then a second print job 12. In each print job 11, 12, the assembly 11.1, 12.1 of the printing plate 2 is applied to the forme cylinder 1, in a second application step 11.2, 12.2 in a first order step the setting up of the inking unit 3, in a third order step 11.3, 12.3 the print run and in a fourth order step the disassembly 11.4, 12.4 of the printing plate 2 from the forme cylinder 1. The printing plate 2, which in the order steps 11.1, 11.4 of the first print job 11 is mounted and dismounted, is different with respect to their printed image of the printing plate 2, which is mounted in the order steps 12.1, 12.4 of the second print job 12 and disassembled.

When setting up the inking unit 3 in the second order step 11.2 of the first print job 11 occurs regularly or in a predictable manner, a pressure interruption 13, wherein during a portion E (see FIG. FIG. 3 ) The sheet transport of the printing machine is interrupted.

The control device 10 controls the inking unit 3 such that during a section A (see. FIG. 3 ) of the print interruption 13 no more color is transferred from the ink fountain 4 to the distributor roller 8, wherein the control device 10 implements one of the following three variants according to the program:
In the first variant, the control device 10 controls the metering device 5 in such a way that their metering elements in all ink zones are adjusted so close to the ink fountain roller 6 that in the section A no more ink is conveyed out of the ink fountain 4 by the rotating ink fountain roller 6 becomes. In each color zone so the so-called color zone setting "zero" is set. The control device 10 controls the servomotors of the metering accordingly.

In the second variant, the control device 10 controls the ink fountain roller 6 so that it no longer rotates. Due to the rotational standstill of the ink fountain roller 6 promotes this in the section A of the print interruption 13 no color from the ink fountain 4 out. The control device 10 controls to a motor of the ink fountain roller 6 or a clutch via which the ink fountain roller 10 is connected to the motor, according to the running in the control device 10 program.

In the third variant, the control device 10 controls the lifting roller 7 in such a way that it no longer executes a pendulum movement. During the section A of the printing interruption 13, the lifting roller 7 can be in rolling contact only with the ink fountain roller 6 (and not with the distributor roller 8) or in rolling contact only with the distributor roller 8 (and not with the ink fountain roller 6) or out of contact with both rollers. 6 , 8 are located. The control device 10 controls to a motor of the lifting roller 7 or a clutch, via which the lifting roller 7 is connected to the motor, according to the running in the control device 10 program.

In all three variants, it is provided in the program of the control device 10 that the interruption of the ink supply from the ink fountain 4 is automatically triggered by the triggering of the print interruption 13 on the distributor roller 8 and the ink supply is interrupted during the entire section A and that by stopping (Print start) the print interruption 13 automatically a color run of the color from the ink fountain 4 in the remaining inking unit 3 takes place. The print start is triggered by the operator at the push of a button. The color run takes place in a temporal section D (cf. FIG. 3 ) and at the ink inlet rotates the ink fountain roller 6, oscillates the lifting roller 7 and are no longer all metering of the metering device 5 in the ink zone setting "zero". The metering elements can be set during the ink feed to a zonal metering profile (ink feed metering profile), which differs from a zonal metering profile (continuous metering profile) to which the metering elements are set in the continuous printing after the ink feed. The ink feed metering profile can be inverse with respect to the continuous metering profile, so that the ink feed metering on the one hand those metering are more closed, which are more open in the continuous metering profile, and on the other hand, those metering are more open, in the continuous metering profile are more closed. The ink run-in dosing profile serves to achieve a print color compatible, and the Fortdruck-Dosierprofil corresponding, stable color guide faster.

The lifting roller 7 is rotatably mounted in a lever which is pivotally mounted in a hinge. In printing operation and in a section D (see. FIG. 3 ) of the pressure interruption 13 drives the motor of the lifting roller 7 via a cam gear to the lever so that it pivots about the joint back and forth to cause the pendulum movement of the lifting roller 7.

In FIG. 3 a layer thickness-time diagram of the layer thickness of a color profile 14 in the inking unit 3 is shown. The section A consists of a section B and a section C and is triggered automatically or by the operator by pressing a button. In the entire section A, the ink supply is interrupted according to one of the three variants explained. In section B, the sheets are still transported by the transport cylinder and the counter-pressure cylinder, from the sheet feeder to the sheet delivery and thereby by the illustrated printing unit. In this case, the sheets are printed in the printing unit and is - because no color replenishment from the ink fountain 4 takes place - consequently the ink quantity located in the inking unit between the vibrating roller 7 and forme cylinder 1 is reduced.

The color profile 14 located in this inking area becomes in section B from a total layer thickness 15 to a build-up layer thickness 16 to a base layer thickness 17 reduced. The base layer thickness 17 is uniform regardless of the area coverage to be printed and on all rollers of the inking unit. The build-up layer thickness 16 is determined by the previously described continuous metering profile of the metering device 5 and is dependent on the area coverage to be printed in the different inking zones and not evenly on the rollers: Within the compactor takes the build-layer thickness 16 due to the color separation of the distributor roller 8 to inking rollers down. Therefore, the build-up layer thickness 16 is also referred to as a color wedge.

The number of sheets printed in the section B is 14 (when the squeegee roller 7 is half-revolving, that is, oscillating per 2 revolutions of the forme cylinder 1) or 15 (when the squeegee roller 7 is three-thirds, that is one pendulum vibration per 3 revolutions of the forme cylinder 1 executes.) Are good and are not rejected as waste paper from the stack of sheets in the sheet delivery or before the delivery of this stack. In the section C, the build-up layer thickness 16 in said inking area is completely reduced by the printing of the 14 or 15 sheets and there is only the base layer thickness 17 therein. In the section C, there is no more sheet transport in the printing press and those associated with the print interruption 13 standing works, z. As the color measurement and the color control, performed by the operator.

In the section C, the rollers of the inking unit including the distributor roller 8 rotate to keep the rheological properties of the thixotropic ink in the inking unit constant by color-splitting. Because color run-in is performed in section D, it is not necessary to stop the axial traversing movement of the distributor roller 8 (and other distributor rollers of the inking unit 3) during section C. Otherwise required means for stopping the traversing movement, z. As clutches, can be omitted, causing the manufacturing cost of the printing press decline. The make-up layer 16, which is degraded in section B by printing the 14 or 15 sheets without ink supply and rebuilt in section D through the ink run, is the carrier of the print image appropriate color distribution in the ink zones - the zonal color distribution. For reasons explained exists in the Process according to the invention no risk that the zonal color distribution by the axial traversing movement of the distributor roller (s) is made uniform, "triturated".

A section E consists of the section C and the adjoining section D. In the entire section E is no sheet transport through the printing press and the printing unit. The transfer cylinders and the impression cylinders of the printing press rotate during section D, but without transporting sheets. The section D takes exactly as many cylinder revolutions of the forme cylinder 1, the blanket cylinder 9, the transport cylinder and the counter-pressure cylinder as the section B. Regarding the time duration, however, the sections B and D may differ from each other, for. Example, if they differ from each other in terms of cylinder speeds or cylinder speeds. At the end of section D, which is also the end of section E, the build-up layer 16 is completely rebuilt by means of the paint feed and, under program control, resumes sheet transport and printing operation. From this point on, the sheets will be printed again in the printing unit.

LIST OF REFERENCE NUMBERS

1

form cylinder

2

printing plate

3

inking

4

paintbox

5

metering

6

Ink fountain roller

7

vibrator roller

8th

distributor roller

9

rubber cylinder

10

control device

11

first print job

12

second print job

11.1, 12.1

first order step

11.2, 12.2

second order step

11.3, 12.3

third order step

11.4, 12.4

fourth order step

13

print interruption

14

color profile

15

Total layer thickness

16

Construction thickness

17

Base layer thickness

A - E

section

Claims (9)

1. Method for operating a printing press,
   wherein upon an interruption (13) of the printing process other than an emergency stop during a print job (11),
   in a first step, an ink profile (14) in an inking unit (3) is at least partly evened out by interrupting the supply of ink and printing a defined number of sheets while the ink supply is interrupted and by having a cylinder (1) that is a forme cylinder, a blanket cylinder, or an impression cylinder of a printing unit that the inking unit (3) belongs to, carry out a defined number of revolutions in the process, and
   wherein in a second step, the ink profile (14) is completely built up again by resuming the supply of ink and carrying out a reintroduction of ink without printing on the same defined number of sheets while the cylinder (1) carries out the same defined number of revolutions in the process.
2. Method according to claim 1,
   wherein the interruption (13) of the printing process is
   a machine stop for color measurement or color control purposes while the press is being set up or
   a machine stop to wash a blanket or
   a machine stop due to defective sheets in the production run or
   a machine stop once an ok sheet has been achieved while the press is being set up and before the production run starts or
   a machine stop to carry out a sheet stack change or
   a foreseeable printing break.
3. Method according to any one of claims 1 to 2,
   wherein in the first step, the movement of a roller that is an ink fountain roller (6) or a vibrator roller (7) is stopped to interrupt the supply of ink.
4. Method according to claim 4,
   wherein the roller is an ink fountain roller (6).
5. Method according to claim 3,
   wherein the roller is a vibrator roller (7).
6. Method according to one of claims 1 to 2, wherein in the first step all ink zones of a metering device (5) are closed to interrupt the supply of ink.
7. Method according to any one of claims 1 to 6,
   wherein during the interruption (13) of the printing process one or more distributor rollers (8) of the inking unit (3) reciprocate in an axial direction.
8. Method according to any one of claims 1 to 7, wherein the defined number of sheets that are printed in the first step are used as acceptable sheets.
9. Method according to any one of claims 1 to 8,
   characterized in
   that one and the same printing plate (2) is used in the printing process before and after the interruption of the printing process.

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