EP1149696A2 - Offset printing unit for a printing machine - Google Patents

Abstract

An offset printing system has a water dosing system (3) with the water applicator roller (6) fitted with adjustable scrapers (11) to control the thickness of film and to remove and ink transferred from the print roller (10. The water dosing system can be set for either wet or dry and is positioned on the print roller in front of the ink applicator system (4).

Description

The invention relates to an offset printing unit for a printing press, the one a printing form-bearing plate cylinder, which at least with on and adjustable inking rollers of an inking unit are functionally connected, has, according to the preamble of the independent claims.

An offset printing unit of this type is from DE 34 16 845 A1 with an inking unit and a dampening system. Then the dampening system is in the Essentially from a supply device for the dampening solution with a Device for dosing the dampening solution film and an applicator roller transfers the dampening solution film to a plate cylinder and with the adjacent inking unit can be coupled or operated separately. The dampening roller can be different from the plate cylinder Have peripheral speed, so that for example foreign particles eliminating wiping effect.

DE 34 32 807 A1 in conjunction with US Pat. No. 4,724,764 is a advanced offset printing unit known. In addition to optionally different The peripheral speed of the plate cylinder and dampening roller is one ink-absorbing roller as the so-called rider roller of the dampening roller assigned. The ink-absorbing roller rotates with one to Plate cylinder different peripheral speed and can with a adjacent inking unit can be coupled or operated separately from this.

A disadvantage of these designs is that they are on the dampening roller accumulating ink is fed into the dampening system and thus the ink / Dampening solution balance is impaired. These impairments show in the form of stencils or cord strips (streaks).

From DE 4404898 A1 an offset printing unit is known, which is universal in Offset printing is operable. The offset printing unit is of the operating mode Wet offset can be changed to dry offset mode by using the ink-carrying plate cylinder in contact with a dampening roller Separation point decoupled from a dampening solution supply and with a Differential speed to the peripheral speed of the plate cylinder is drivable. The disadvantage here is that in the contact zone with the Plate cylinder a breakdown of color or a color split occurs and that thereby an uneven color and an impairment of Print quality occurs.

According to DE 4423286 A1 is a printing unit for a rotary offset printing press with a plate cylinder, which one for the dampening agent-free offset printing suitable pressure plate carries, known. The inking unit is to be eliminated an additional roller assigned to impurities, which in a first Operating position can be set independently of the inking rollers on the printing plate is and against the direction of rotation of the plate cylinder with a Circumferential speed of the plate cylinder deviates Peripheral speed is drivable. In a second operating position Additional roller - starting from the first operating position - into the inking unit integrated.

The invention is based on the object of an offset printing unit at the outset to create described type that avoids the disadvantages mentioned, the in particular, process-stable color guidance on a plate cylinder supports and noticeably improves the print quality.

According to the invention, this is solved by the training features of independent claims 1, 2 and 3. Further developments result from the dependent claims.

A first advantage of the invention is that in the direction of rotation of the Plate cylinder in front of an inking unit arranged in the Wet offset operation with a dampening solution supply or in dry offset operation with a dampening solution-free offset printing with interrupted or switched off or can be used without a dampening solution supply and in all operating modes the print quality is noticeably improved. It was found that on the outer surface of such an application roller in Direction of rotation after tearing off paint or splitting color, especially when tearing off in a contact zone of Applicator roller and ink-guiding plate cylinder, no uniform Color distribution - viewed across the roller width - is present. It is on the Application roller before an uneven surface topography of the color, which by residual color split back from the colored plate cylinder in the form of Color peaks or color crests and color valleys on the lateral surface of the Application roller is characterized. Depending on the above Operating mode next to the Paint also dampening solution can be led from the applicator roller.

Furthermore - as a result of a previous demolition of paint or an ink split in one by an applicator roller and an ink roller Plate cylinder (with printing form) formed contact zone - an uneven Surface topography on the surface of the applicator roller, which is also dependent on the respective print subject.

It is advantageous that the application roller is uneven in the direction of rotation Surface topography after such a contact zone at least before a renewed demolition of color or a color split in another Contact zone can be switched on and preferably switched off by means of at least one in parallel arranged plating device is leveled.

Another advantage is that in addition to the on the outer surface of the Application roller leveled surface topography by means of at least one Plating device the subject-related color structure on the applicator roller is equalizable. The leveling of the color structure and the leveled Surface topography stabilize the in wet offset operation Dampening solution feed to the application roller and from the application roller to the Plate cylinder, reducing the risk of emulsifying in the inking unit, thereby the process-stable ink flow on the plate cylinder or in the inking unit is supported, and noticeably improve the print quality on the substrate. In dry offset printing, the equalized color structure and the leveled surface topography the recording of possible Soiling, for example slugs, is reduced, which makes the process stable Color guidance on the plate cylinder or in the inking unit is supported, and the Print quality is noticeably improved.

It is also advantageous that the arrangement of at least one plating device on the lateral surface of the applicator roller reduces the tendency to stenciling (shadow-like markings) during printing and the cord strips causing an uneven printing.
It has been found that in wet offset printing with the application roller and at least one associated plating device, the dampening solution supply from the dampening roller to the application roller can be reduced and the use of alcohol can also be reduced.
It is furthermore advantageous that the applicator roller can be driven to the plate cylinder with either the same or different circumferential speed and that the plating device causes a change in shape of the ink tips, ink domes and ink troughs after tearing or ink splitting towards a flat surface topography. In the case of such a change in shape (plastic change in shape) of the color from an uneven surface topography to a flat surface topography on the lateral surface of the application roller, the ink tips, ink tips slide into the ink troughs. Sliding processes thus take place within the ink layer of the ink structure on the applicator roller, which bring about the plastic shaping - without shearing action of the ink - so that a flat surface topography with a defined layer thickness can be achieved.

Fig. 1

ein Offsetdruckwerk mit einem Farbwerk und einem Feuchtwerk (Nassoffsetbetrieb),

Fig. 2

ein erstes Offsetdruckwerk für den Trockenoffsetbetrieb,

Fig. 3

ein zweites Offsetdruckwerk für den Trockenoffsetbetrieb,

Fig. 4

eine Weiterbildung der Figuren 2 und 3,

Fig. 5

eine Weiterbildung von Figur 1,

Fig. 6

eine Auftragwalze mit einer Plattiereinrichtung mit einem
Plattierelement,

Fig. 7

eine Auftragwalze mit einer Plattiereinrichtung mit doppelt angeordneten Plattierelementen.

The invention will be explained in more detail using an exemplary embodiment. Show:

Fig. 1

an offset printing unit with an inking unit and a dampening unit (wet offset operation),

Fig. 2

a first offset printing unit for dry offset printing,

Fig. 3

a second offset printing unit for dry offset printing,

Fig. 4

a further development of FIGS. 2 and 3,

Fig. 5

a development of Figure 1,

Fig. 6

an application roller with a plating device with a
Cladding element,

Fig. 7

an application roller with a plating device with double arranged plating elements.

A plate cylinder 1 carries a printing form and is shown in FIG. 1 with a Blanket cylinder 2, a dampening unit 3 and a downstream inking unit 4 in functional connection. The inking unit 4 consists of several on and color rollers 5, which are arranged so as to be adjustable, with rollers to be supplied with ink (not designated further) are connected. The dampening unit 3 is - in the direction of rotation of the plate cylinder 1 considered - upstream of the inking unit 4 and consists in present example from a dampening solution container 9, a dampening duct 7, a metering roller 8 and an applicator roller 6. The applicator roller 6 is in one first contact zone 12 with the inkable via the inking unit 4 Plate cylinder 1 can be switched on and off in a functional connection. At least that The dampening solution container 9 and the dampening duct 7 form the Fountain solution supply device, which in a second contact zone 16 with the Application roller 6 is in functional connection.

In the direction of rotation of the applicator roller 6, after the first contact zone 12, at least one plating device 11 can be placed on the lateral surface of the applicator roller 6 in parallel, and preferably placed on it. The application roller 6 can be driven optionally with a peripheral speed that is the same as or different from the peripheral speed of the plate cylinder 1.
In wet offset operation, at least one plating device 11 is preferably arranged in the direction of rotation of the application roller 6 in front of the dampening solution supply 7-9 which is functionally connected to the application roller 6 in the second contact zone 16.
In a further development, in the direction of rotation of the application roller 6, after the second contact zone 16 and before the first contact zone 12, a further (structurally identical) plating device 11 is arranged on and off the outer surface of the application roller 6.

In the dry offset, the application roller 6 is in the direction of rotation after the first Contact zone 12 with the plate cylinder 1 at least one plating device 11 arranged on and off on the lateral surface of the applicator roller 6 and the Applicator roller 6 is optionally with a to the peripheral speed of Plate cylinder 1 same or different peripheral speed drivable and with the dampening solution supply switched off 7- 9 in the first Contact zone 12 placed on the plate cylinder 1.

In a further mode of operation for dry offset, the offset printing unit no dampening. In the direction of rotation of the applicator roller 6 is after the first Contact zone 12 with the plate cylinder 1 at least one plating device 11 arranged on and off on the outer surface of the applicator roller 6. It is the applicator roller 6 optionally with a peripheral speed of Plate cylinder 1 same or different peripheral speed can be driven, the application roller 6 in the direction of rotation of the plate cylinder 1 is arranged upstream of the inking rollers 5 of the inking unit 4.

In the operating modes for dry offset, the plate cylinder 1 carries one for printing form suitable for dampening agent-free offset printing. The plate cylinder 1 the inking rollers 5 of the inking unit 4 are in turn assigned Color the printing form with a printing ink suitable for dry offset. The applicator roller 6 is independent of the inking rollers 5 ink-carrying printing form or the plate cylinder 1 in the first contact zone 12 arranged on and off. The application roller 6 is in the direction of rotation after the first contact zone 12, in which a tearing off of paint or a color splitting takes place, at least one plating device 11 can be switched on and preferably switched off The outer surface of the applicator roller 6 is arranged. The application roller 6 is there optionally with the same or different circumferential speed - based on the peripheral speed of the plate cylinder 1 - can be driven in rotation, for example via a switchable positive drive.

If the applicator roller 6 is preceded by a dampening solution supply 7-9, this is interrupted in a separation point 10.

In a preferred development, regardless of the respective operating mode, at least one plating device 11 is coupled to an axially acting traversing drive. Alternatively, all plating devices 11 are coupled to such a traversing drive. On the drive side, the traversing drive is preferably functionally connected to the drivable plate cylinder 1 in terms of transmission technology.
In the operating mode for the wet offset, at least the plating device 11 arranged in front of the contact zone 16 can be driven to be changeable.

In printing operation, the applicator roller 6 is optionally available with a The peripheral speed of the plate cylinder 1 is the same or different Peripheral speed drivable. For this purpose, the applicator roller 6 is on the drive side preferably geared technically with the drivable plate cylinder 1 in Functional connection.

The plating devices 11 are preferably in their direction of rotation of the application roller 6
Arranged tangentially or secant-shaped on the lateral surface of the applicator roller 6 and arranged. Each plating device 11 can preferably be set against the outer surface of the application roller 6 by means of a force F, for example applied by a compression spring. A plating device 11 can preferably also be used to apply a uniform surface pressure over the width of the application roller 6 or the uneven surface topography of the ink.

In a preferred embodiment, the plating device 11 is in its Inclination angle to the outer surface of the application roller 6 adjustable.

In a further embodiment, at least one plating device 11 consists of a plating element 13, which extends over the width of the application roller 6 and is detachably arranged in a holder 14. The holder 14 is preferably arranged on the frame side in a bilateral bearing 15. At least one plating device 11 is preferably arranged in a bearing 15 on both sides in the direction of rotation of the applicator roller 6, for example in one swivel joint each. In a preferred development, the bearing 15 is movable in such a way that the cladding element 11 is arranged so as to be adjustable in its angle of inclination (FIG. 6.7 double arrow) relative to the application roller 6. Preferably, the free end of the cladding element 13 is arranged tangentially or secantly on the lateral surface of the application roller 6, preferably ending in a tangent or secant point.
In a further embodiment, the free end of the preferably adjustable plating element 13 ends at a slight distance from the outer surface of the application roller 6. The distance is such that a leveling of an uneven surface topography 19 can be achieved.

In an operating mode for dry offset, the plate cylinder 1 carries one for the Suitable printing form for dampening agent-free offset printing. The plate cylinder 1 are in turn assigned the inking rollers 5 of the inking unit 4, which the Color the printing form with a printing ink suitable for dry offset. The Applicator roller 6 is in the direction of rotation of the plate cylinder 1 before Ink application rollers 5 arranged. Furthermore, the applicator roller 6 is independent from the inking rollers 5 to the ink-guiding printing form or the Plate cylinder 1 arranged in the first contact zone 12 on and off. The application roller 6 is in the direction of rotation after the first contact zone 12 in the tearing off or splitting of color takes place, at least one Plating device 11 can be switched on and preferably switched off to the lateral surface of the Application roller 6 arranged. The application roller 6 is optionally the same or uneven peripheral speed - based on the Peripheral speed of the plate cylinder 1 - can be driven in rotation, for example via a switchable positive drive.

If the applicator roller 6 is preceded by a dampening solution supply 7-9, this is interrupted or switched off in a separation point 10.

In Fig. 3 the applicator roller 6 is for the dry offset mode at least one plating device 11 to the inking rollers 5 of the Inking unit 4 separately, in the direction of rotation of the plate cylinder 1, in front of the inking unit 4 arranged and forms with the plate cylinder 1, the first contact zone 12. In FIG. 4 shows a further development, such that the application roller 6 with at least one plating device 11, in the direction of rotation of the plate cylinder 1, is arranged in front of the inking unit 4 and with the plate cylinder 1 Contact zone 12 forms. In addition, the applicator roller 6 is a bridge roller 17 in Contact associated with that in the direction of rotation of the plate cylinder 1 first inking roller 5 of the inking unit 4 is in contact. In this Training, the applicator roller 6 can be used as an additional inking roller. In Direction of rotation of the application roller 6 is at least one plating device 11 the first contact zone 12 and / or after the contact zone of the bridge roller 17 and application roller 6 on the lateral surface of the application roller 6 on / off.

In FIG. 5, the application roller 6 is in the first for the wet offset mode of operation Contact zone 12 in contact with the plate cylinder 1. In addition, the Applicator roller 6 assigned a bridge roller 18 in contact, optionally separately with the application roller 6 or with the in the direction of rotation of the plate cylinder 1 first inking roller 5 of the inking unit 4 and the application roller 6 in contact is. At least one plating device 11 is in the direction of rotation of the application roller 6 after the first contact zone 12 and / or after the contact zone of Bridge roller 18 and applicator roller 6 can be turned on / off on the lateral surface of the applicator roller 6.

6 and 7, the applicator roller 6 with at least one Plating device 11 shown, wherein the plating device 11 in Fig. 6 by a plating element 13 with holder 14, which extends across the roll width and storage 15 is formed. In Fig. 7 is another about the Platen 11 extending roller width shown, the double arranged plating elements 13. The cladding elements 13 overlap themselves in a defined area and are preferably in a common area Bracket 14 and a bearing 15 added. The free ends of the Plating elements 13 end in different tangents or secants Points on the outer surface of the applicator roller 6. This is with the in Direction of rotation of the application roller 6 first plating element 13 a first leveling and a second leveling with the downstream second plating element 13 the remaining ink (with or without dampening solution) can be achieved on the applicator roller 6. In this embodiment too, the plating device 11 is at an angle of inclination arranged adjustable.

FIGS. 6, 7 show that regardless of the mode of operation in Direction of rotation of the application roller 6 after the contact zone 12 with the inked Plate cylinder 1 (in which there is a color break or a color split) on the The lateral surface of the application roller 6 has an uneven surface topography 19 in Form of color tips, color crests and color valleys is present. Happens that Applicator roller 6 the plating device 11 connected downstream in the direction of rotation, see above becomes the uneven surface topography - without shearing of the Plating device 11 - leveled cohesively and there is a flat Surface topography 20 of the ink on the applicator roller 6 before. Through the flat surface topography 20 becomes the wetting behavior of the Application roller 6 improved with a dampening solution (wet offset) and one improved ink guidance on the plate cylinder1 or the printing form. in the Dry offset causes a flat surface topography 20 on the Applicator roller 6 an improved ink guide on the plate cylinder 1 and the Printing form.

Each plating device 11 is in the direction of rotation of the applicator roller 6 after Contact point 12 to improve the cohesion of the color preferably with a uniform surface pressure and the outer surface of the application roller 6 assigned.

The is independent of the operating modes wet offset or dry offset Applicator roller 6 always optionally with a peripheral speed of Plate cylinder 1 same or different peripheral speed drivable.

REFERENCE NUMBERS

1

Plate cylinder

2

Blanket cylinder

3

Dampening system

4

Inking unit

5

Inking roller

6

Applicator roller

7

Damp doctor

8th

Dosing roller

9

Fountain solution container

10

Separation point

11

Plating device

12th

1. Contact zone

13

Cladding element

14

bracket

15

storage

16

2nd contact zone

17

Bridge roller (dry offset)

18th

Bridge roller (wet offset)

19

uneven surface topography

20th

flat surface topography

F

force

Claims (10)

Offset printing unit for a printing press, with a plate cylinder carrying a printing form, which is functionally connected to the inking rollers of an inking unit, which can be switched on and off, and a dampening unit with at least one fountain solution supply device and an application roller forming a contact zone with the plate cylinder,
characterized in that in the direction of rotation of the application roller (6) after the first contact zone (12) with the plate cylinder (1) at least one plating device (11) is arranged on and off against the lateral surface of the application roller (6) and that the application roller (6 ) can optionally be driven with a circumferential speed that is the same as or different from the circumferential speed of the plate cylinder (1). Offset printing unit for a printing press, with a plate cylinder carrying a printing form, which is functionally connected to the inking rollers of an inking unit, which can be switched on and off, and a dampening unit with at least one fountain solution supply device and an application roller forming a contact zone with the plate cylinder,
characterized in that in the direction of rotation of the application roller (6) after the first contact zone (12) with the plate cylinder (1) at least one plating device (11) is arranged on and off against the lateral surface of the application roller (6) and that the application roller (6 ) can be driven either with a circumferential speed that is the same or different to the circumferential speed of the plate cylinder (1) and is set against the plate cylinder (1) in the first contact zone (12) with the dampening solution supply switched off. Offset printing unit for a printing press, with a plate cylinder carrying a printing form for dampening agent-free offset printing, which is functionally connected to inking rollers of an inking unit which can be switched on and off and an application roller which is independent of the inking rollers and forms a contact zone with the plate cylinder,
characterized in that in the direction of rotation of the application roller (6) after the first contact zone (12) with the plate cylinder (1) at least one plating device (11) is arranged on and off against the lateral surface of the application roller (6) and that the application roller (6 ) can optionally be driven with a circumferential speed that is the same as or different from the circumferential speed of the plate cylinder (1), the application roller (6) being arranged upstream of the inking rollers (5) in the direction of rotation of the plate cylinder (1). Offset printing unit according to claim 1 or 2 or 3,
characterized in that the plating device (11) is coupled to an axially moving traversing drive. Offset printing unit according to at least claim 1 or 2 or 3,
characterized in that the plating device (11) is arranged in the direction of rotation of the application roller (6) in its direction tangential or secant to the lateral surface of the application roller (6). Offset printing unit according to at least claim 1 or 2 or 3,
characterized in that the plating device (11) is adjustable in its angle of inclination to the lateral surface of the application roller (6). Offset printing unit according to at least claim 1 or 2 or 3,
characterized in that the plating device (11) can be used to apply a uniform surface pressure over the axial width of the application roller (6). Offset printing unit according to at least claim 1 or 2 or 3,
characterized in that the plating device (11) in the direction of rotation of the application roller (6) has a plating element (13) which extends over the entire width of the roller and is detachably arranged in a holder (14). Offset printing unit according to at least claim 1 or 2 or 3 and 8,
characterized in that the holder (14) is arranged in a bilateral bearing (15). Offset printing unit according to at least claim 1 or 2 or 3 and 8,
characterized in that a free end of the plating element (13) ends tangent-shaped or secant-shaped on the lateral surface of the application roller (6).

Images