EP0403861B1 - Method of rapid attainment of print-readiness - Google Patents

Description

The invention relates to a method for producing a color profile close to production for an offset printing press with a dampening unit and an inking unit, which has an ink metering device for setting a color profile, the inking unit and the dampening unit each having at least one applicator roller that can be moved to a printing form when in contact .

In offset printing machines, it is necessary that a thin ink film is fed to the printing form wetted with dampening solution. An inking unit provided with a large number of rollers is used for this. The dampening solution is supplied by means of a dampening unit, which also has a roller arrangement. Depending on the subject of the printing form, an appropriately adapted color distribution across the printing direction of the offset printing press is required in order to achieve a good printing result. The inking unit therefore has a color metering device which allows the zonal setting of a color profile. Depending on the setting of the individual zones, a corresponding color layer thickness results.

Before the actual printing, a so-called ink run-in is also carried out, in which the said color film is built up within the inking unit. Movable applicator rollers are at a distance from the printing form so that no inking takes place yet.

In addition to the color distribution in the circumferential direction, the color is also distributed laterally at the ink inlet by traversing friction rollers. This keeps the color supple and evenly distributed on the side. In addition, unwanted color accumulations can be avoided. The lateral rubbing leads z. B. at the ink inlet to the fact that the color profile built up by the ink metering device is evened out to a certain extent, so that it is not immediately available to the desired extent in the initial phase in the subsequent printing process.

The problems described also arise when a so-called stopper occurs, ie one short interruption of the printing process and also during a printing break for washing the blanket cylinder of the offset printing machine, since when the printing process is started again there is initially no sufficient color profiling.

From DE-OS 37 07 695 a method for the defined generation of a near-production color distribution in the inking unit of rotary printing presses is known, in which, before the start of printing, the color profile present in the inking unit from the previous print job when the machine is rotating by closing the ink metering elements and by returning the zonal quantities of ink present in the inking unit in the inking unit are reduced in such a way that a profile-independent ink layer thickness remains and then the ink profile required for the subsequent print job in the inking unit is carried out by zone-setting the ink metering elements with a defined number of inking unit roller revolutions.

An inking unit presetting is known from DE-OS 33 38 143. In order to be able to define the distribution of the printing ink in the inking unit and to make it close to the production state, a precisely measured amount of ink is fed to the inking unit rollers before the start of printing, so that a predetermined ink layer thickness distribution is established on the inking unit rollers.

DE-OS 15 61 100 shows an inking unit of rotary printing presses which has controllable lifting means in order to be able to separate certain groups of rollers. Relocate these lifting devices also the application rollers interacting with the printing form. In the event of a print interruption, the lifting means separate certain roller groups and also shut down the application rollers.

In contrast, the invention is based on the object of creating an offset printing machine in which a color distribution close to the continuous printing is set up particularly quickly, so that waste is largely avoided.

This object is achieved - based on the features known from the offset printing machine mentioned at the outset - according to the invention in that the application rollers of the inking and dampening unit are permanently or intermittently during the running in of the ink before the start of printing or during a stop or blanket which interrupts the production process -Washing process are applied by a control device to the rotating printing form and that the control device in this case reduces the amount of dampening solution supplied compared to the amount supplied during continuous printing. The rotating applicator rollers of the inking and dampening units thus do not take up the distance from the rotating printing form known from the prior art during the non-printing time, but remain in the contact position according to the invention. The result of this is that the subject of the printing plate has a supporting effect on the color distribution in such a way that a color profile that largely corresponds to the subject is established. Thus, the color profile set at the ink metering device, but which is again to a certain extent comparable due to the subsequent friction rollers, is reduced by the Measure according to the invention, in particular on the application rollers, is reconstructed by interaction or reaction with the printing plate, so that a zonal ink supply with the required profiling takes place at the beginning of printing or immediately thereafter. According to the invention, not only the applicator rollers of the inking unit, but also those of the dampening unit, take up their abutment on the printing form in order to bring about the desired reaction process and also to prevent toning of areas of the subject which are actually color-free.

In addition, it is provided that the control device reduces the amount of fountain solution supplied during the ink run-in, during the stopper or during the blanket washing process compared to the amount supplied during production. This avoids excess dampening solution on the printing plate. The dampening solution supply is preferably set to a value which covers any losses which occur (for example due to evaporation), so that there is a balance.

According to a further embodiment of the invention it is provided that at the same time as or after the inking of the printing forme caused by the contact position of the application rollers and the blanket of a blanket cylinder of the offset printing press is also colored and a printing cylinder during the inking of the blanket a spacing position from the blanket of the blanket cylinder. In addition to the inking of the printing form through the contact position of the application rollers of the inking and dampening unit, this also engages a contact position between the printing form and the rubber blanket, which supports the rapid attainment of the production status. The interaction between the blanket and the printing form also has a positive influence on the color distribution, so that the production of a color distribution close to the continuous printing color distribution profile is supported. The rubber blanket is inked before the actual printing begins.

In order to prevent a printing cylinder of the offset printing machine from becoming contaminated with the ink / water emulsion, it assumes a spacing position from the rubber blanket or rubber blanket cylinder during the coloring of the rubber blanket. It is for the use of the printing presses currently available on the market, it is advantageously possible to transfer the printing press to its printing operation position for inking the rubber blanket, but without commencing printing operation, whereby — in deviation from the normal printing operation position — a printing provision acting between the blanket cylinder and the printing cylinder is provided is driven out of their working area in the production position that the rubber blanket of the blanket cylinder and the printing cylinder take up the spacing position. It is therefore used according to the invention for the purpose of balancing the paper thickness, by making a relative shift between the blanket cylinder and the printing cylinder beyond their usual working range, so that the colored rubber blanket does not touch the printing cylinder.

According to a special exemplary embodiment, it is possible for the ink metering device to be adjusted automatically in coordination with the dampening unit control and the application rollers via a ink control device in accordance with the respective operating state in order to achieve optimum production conditions.

The process with a control device assigned to the application rollers is supported in that the application rollers can be adjusted by the control device for a few revolutions of the plate cylinder to the printing plate attached to its outer surface before the printing cylinder is turned on.

Figur 1

ein Walzenschema einer Offset-Druckmaschine mit in Anlagestellung zu einem Druckzylinder verlagerten Auftragwalzen eines Farb und Feuchtwerks,

Figur 2

eine der Figur 1 entsprechende Darstel lung, die eine Verlagerungsmöglichkeit der Auftragwalzen andeutet,

Figur 3

eine Prinzipdarstellung einer Farbdosier einrichtung sowie ein Diagramm eines Farbprofils,

Figur 4

ein Diagramm, das die sich einstellende durchschnittliche Volltondichte nach Druckaufnahme wiedergibt,

Figur 5

ein der Figur 4 entsprechendes Diagramm einer Zone der Farbdosiereinrichtung mit hoher Farbzuführung,

Figur 6

ein der Figur 5 entsprechendes Diagramm einer Zone mit geringer Farbzuführung,

Figur 7

ein Diagramm des Volltondichteverlaufs nach einem Papierstop,

Figur 8

ein der Figur 7 entsprechendes Diagramm nach einem Anlegerstop,

Figur 9

ein der Figur 8 entsprechendes Diagramm mit Überfeuchtungsvorgang,

Figur 10

eine schematische Darstellung der Anordnung eines Platten-, Gummituch- und Druckzylinders vor einem Einfärbvorgang eines Gummituchs des Gummituchzylinders,

Figur 11

eine Darstellung gemäß der Figur 10, je doch während des Einfärbvorgangs des Gummituchs und

Figur 12

eine Darstellung gemäß der Figur 11, je doch in Fortdruckstellung der Offset-Druckmaschine.

The invention is explained in more detail below with reference to the figures. Show it:

Figure 1

1 shows a roller diagram of an offset printing machine with application rollers of an inking and dampening unit which are shifted into the contact position with a printing cylinder,

Figure 2

1 a representation corresponding to FIG. 1, which indicates a possibility of relocating the application rollers,

Figure 3

a schematic representation of a color metering device and a diagram of a color profile,

Figure 4

a diagram that shows the resulting average solid density after pressure,

Figure 5

4 shows a diagram of a zone of the ink metering device with high ink supply corresponding to FIG. 4,

Figure 6

5 shows a diagram corresponding to FIG. 5 of a zone with little ink supply,

Figure 7

a diagram of the full-tone density curve after a paper stop,

Figure 8

7 shows a diagram corresponding to FIG. 7 after a feeder stop,

Figure 9

8 shows a diagram corresponding to FIG. 8 with over-moistening process,

Figure 10

1 shows a schematic representation of the arrangement of a plate, blanket and impression cylinder before a coloring process of a blanket of the blanket cylinder,

Figure 11

a representation according to Figure 10, but during the coloring process of the rubber blanket and

Figure 12

a representation according to Figure 11, but in the printing position of the offset printing press.

Figure 1 shows a schematic representation of an inking unit 1 and a dampening unit 2 of an offset printing machine. The inking unit 1 has an ink fountain 3 with an ink metering device, from which an ink fountain pen 4 doses ink during operation. A jack roller 5 interacts with the ink duct 4 and with a driven distribution cylinder 6. Inking and dampening units 1, 2 also have further drive cylinders 7, 8, 9 and 10 provided with a drive. Furthermore, six rider and transfer rollers 11 to 16 and two rubber rollers 17 and 18 are provided. The inking unit 1 also has two rubber rollers 19 and 20 and three further, larger-diameter rubber rollers 21 to 23. Furthermore, two rubber rollers 24 and 25 are provided with a smaller diameter than the rubber rollers 19 and 20.

The dampening unit 1 has a container 26, which is filled with dampening solution 27, into which an immersion roller 28 immersed with a portion of its circumference. The dipping roller 28 interacts with a metering roller 29. Furthermore, a rubber roller 30 and an intermediate roller 31 are provided.

Both ink and fountain solution are fed to a printing form 32 via the roller arrangement described. The printing form 32 is designed as a plate cylinder 33, on the circumference of which a printing plate, not shown, is clamped.

The transfer of ink and dampening solution from the inking unit 1 or dampening unit 2 to the printing plate is carried out by the rubber rollers 18, 20, 23, 25 and 30, which are therefore also referred to as application rollers 34.

The offset printing machine has a control device 35 (not shown in more detail) which enables the application rollers 34 to be displaced.

A paint metering device 36 is arranged on the paint box 3 and is shown schematically in FIG. The color metering device 36 enables a zonal setting of a color profile, which is shown by way of example in the diagram in FIG. 3, via the longitudinal extent of the color ductor 4. In each zone 37, the amount of ink delivery (ink layer thickness F) can be adjusted so that it is adapted to the ink requirements of the subject of the printing plate.

By means of the control device 35, the application rollers 34 can be moved into the one shown in FIG Move the system position, ie the applicator rollers 34 of the inking unit 1 and dampening unit 2 are in contact with the printing plate clamped on the plate cylinder 33. In FIG. 2, the arrows assigned to the application rollers 34 indicate that a shift can be carried out by means of the control device 35, so that there is a distance between the application rollers 34 and the outer surface of the plate cylinder 33 and thus to the surface of the clamped printing plate.

According to the invention it is provided that before the start of printing, in particular while the ink is running in or during an interruption of the production process, in particular a stopper or blanket washing process, the application rollers 34 remain on the plate cylinder 33 in the contact position according to FIG. 1. In this way, a color profile close to production is achieved. This has the advantage that the desired, subject-related color profile is available within a very short time when the printing process is started or resumed, so that optimal, essentially waste-free printing results are achieved. The application position can also be taken up by the application rollers 34 only temporarily, that is to say during a partial period of the running in of the ink or the interruption.

FIGS. 4, 5 and 6 show, by way of example, diagrams determined in color run-in tests, in which the solid density DV is plotted on the ordinate and the number of sheets produced after the start of printing is reproduced on the abscissa (sheet number BZ). The in Figures 4 to 6 each Solid curve shows the course of the solid density DV with a set color profile and a color run-in period of 6 minutes. The applicator rollers 34 according to FIG. 1 are in their contact position during the ink run-in period. This can take place continuously, that is, during the entire color run-in period or only temporarily. Depending on the circumstances, different investment periods are also conceivable. The system can also be used for a certain number of machine revolutions. During this running-in period or the duration of the installation, the dampening solution supply quantity is increased as follows: Start: 33.3%, then 55.5%, the last 2 minutes 88.8% and finally - in continuous printing - 100%.

In contrast, the line shown in dashed lines in FIGS. 4 to 6 shows the course of the solid density DV according to the method customary in the prior art, i. H. 6 minutes of ink run-in and adjustment of the ink metering device 36 according to the production profile. The application rollers 34 are not moved into the contact position on the plate cylinder 33 until the start of printing. The amount of dampening solution added is 100%.

Finally, the curve consisting of points in FIGS. 4 to 6 likewise shows the course of the solid density DV according to the method known from the prior art: ink run-in time 6 minutes; the color profile is first set evenly over the entire printing width and only after the 6 minutes have passed the production profile.

FIG. 4 shows the average value of the full-tone density DV averaged over all zones 37. It can be clearly seen that according to the method according to the invention, after a relatively small number of arcs, the curve strives for an end value which, in the methods known from the prior art, is only achieved after a significantly larger number of arcs. In the range 100 to 200 sheets, all 3 curves still show an increasing tendency of the solid density DV, although the curve increase is the smallest in the method according to the invention.

The diagram shown in FIG. 5 shows the solid color density DV of a certain zone 37, which - due to the subject - requires a relatively large amount of color. While the full-tone density DV increases only slowly after the start of printing in the known methods, in the method according to the invention it reaches the final value after only a few prints.

The diagram in FIG. 6 shows the solid color density DV of a zone 37 which only requires a small amount of color. Here, too, it can be seen that the final value of the full-tone density DV corresponding to the printing status is reached much earlier in the method according to the invention than in the known methods.

The diagram in FIG. 7 shows the course of the solid ink density DV as a function of the number of sheets BZ during a paper stop, that is to say there is an interruption in the printing status. During the stop, the rotating applicator rollers 34 remain in contact with the rotating plate cylinder 33 according to the invention. The interruption time is 6 minutes, during this time the amount of dampening solution is increased from 44.4% to 55.5% and finally to 66.6%. During the start-up phase it amounts to 66.6% and finally reaches 100% in the printing condition. It can be clearly seen that the full-tone density DV has already reached its final value required for the production process after about 14 sheets.

FIGS. 8 and 9 show the course of the full-tone density DV after a feeder stop. In both cases, according to the invention, the application rollers 34 remain in the bearing position against the plate cylinder 33 during the stop. In the test according to FIG. 8, the start-up takes place after 16 revolutions. This also applies to the experiment according to FIG. 9, but over-moistening is carried out here shortly before start-up. In both cases, the required solid density DV is reached approximately 15 sheets after printing operations are resumed.

The diagrams show in an impressive way that with the help of the offset printing machine according to the invention or when the method according to the invention is carried out, a color profile close to the production run is set within a very short time, so that virtually no waste occurs.

In addition to the measures described above, the rubber blanket of a rubber blanket cylinder 40 can also be colored simultaneously with or after the inking of the printing form 32 (FIGS. 10 to 12).

FIG. 10 shows the plate cylinder 33 as well as a blanket cylinder 40 and a printing cylinder 41 of the offset printing machine. The position of these cylinders in their position before the start of printing is shown: plate cylinder 33 and blanket cylinder 40 are at a distance from one another; blanket cylinders 40 and impression cylinders 41 are also slightly spaced from one another, their spacing being matched to the thickness of the printing material (for example paper). The adjustment to the printing material thickness takes place by means of a so-called, not shown printing supply. This preferably has an electric actuator for positioning.

In order to be able to ink the blanket of the blanket cylinder 40 simultaneously with or after inking the printing form 32, the position of FIG. 11 is adopted. Here there is virtually a printing operation position, but printing operation is not started and, in deviation from the normal production printing position, the blanket cylinder 40 assumes a spacing position from the printing cylinder 41. Printing form 32 and blanket cylinder 40 are in contact with one another, however, so that the inking process can be carried out. The distance between the blanket cylinder 40 and the printing cylinder 41 is brought about by the aforementioned printing provision, in that it is moved out of its working area for paper thickness compensation by means of the electric actuator so that there is no contact between the blanket cylinder 40 and the printing cylinder 41. So there is a new one Use of the known pressure supply before. The rubber blanket is colored during a few revolutions of the corresponding cylinder. If this has taken place, the actual printing operation position can be entered, that is to say the continuous printing state according to FIG. 12 is assumed in that the plate cylinder 33 is in contact with the blanket cylinder 40 and between the blanket cylinder 40 and the printing cylinder 41 to compensate for the paper thickness there is a corresponding distance, which cannot be seen in FIG. 12.

Claims (6)

1. Method for producing an ink profile close to running-on for offset printing machines having an inking unit (1) and a damping unit (2) which has an ink metering device (3, 4) for adjusting an ink profile, the inking unit (1) and the damping unit (2) each having at least one application roller which can be displaced into a contact position with a printing forme, characterized in that the application rollers (34) of the inking unit (1) and damping unit (2) are placed by a control device (35) against the rotating printing forme (32) permanently or temporarily during the running-in of the ink taking place prior to the beginning of printing or during a stoppage or rubber blanket washing operation which interrupts the running-on process, and in that the control device (35) in this case reduces the feed quantity of damping medium compared to the quantity supplied for running-on.
2. Method according to Claim 1, characterized in that the control device (35) carries out an adjustment of the rotary speed of a dipper roller (28) of the damping unit (2).
3. Method according to one of the preceding claims, characterized in that, simultaneously with or after the inking of the printing forme (32) taking place due to the contact position of the application rollers (34) and printing forme (32), the rubber blanket of a blanket cylinder (40) is likewise inked and, in this case, an impression cylinder (41) assumes a remote position relative to the rubber blanket of the blanket cylinder (40) during the inking of the rubber blanket.
4. Method according to one of the preceding claims, characterized in that the offset printing machine assumes its printing operation position for inking the rubber blanket, an adjuster which acts between the blanket cylinder (40) and the impression cylinder (41) being driven out of its operating region prevailing in the running-on position in such a way that the rubber blanket of the blanket cylinder (40) and the impression cylinder (41) assume the remote position relative to one another.
5. Method according to one of the preceding claims, characterized in that the ink metering device is adjusted automatically to achieve optimum running-on conditions in coordination with the damping unit control and the application rollers (34) via an ink control device in accordance with the respectively prevailing operating condition.
6. Method according to one of the preceding claims, having a control device (35) assigned to the application rollers, characterized in that the application rollers (34) can be engaged by the control device (35) with the printing plate, attached to the outer surface of the plate cylinder (33), for some revolutions of the latter before the engagement of the impression cylinder (41) with the blanket cylinder (40).

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