EP1179425B1 - Method for treating a reusable printing form or cylinder in a printing machine - Google Patents

Abstract

A method of processing renewed imagable print forms on plates or cylinders in a printing machine comprises forming an imagable layer (11) on the cylinder overlayer, impinging laser (9) energy from an imaging unit (8) to form the image and also using this unit to remove the image layer while raising the effectiveness of the overlayer. Independent claims are also included for the following: (a) a device as above comprising a laser of controllable power; (b) a device as above having two lasers interconnected by an optical cable or mirror system.

Description

The invention relates to a method for treating reimageable printing plates or printing forme cylinders in printing machines, wherein on the surface to be treated a imageable coating is applied.

The invention further relates to a device for carrying out the method, consisting from an imaging device with a laser, which is assigned to a laser head,

From the document DE 195 08 843 A1 is a method for imaging or for imaging and neutralization of a printing plate of a printing forme cylinder of a printing press known. Here are the printed image information to be applied to the printing plate in digital form. To use the printing plate in the printing press is the a Printed image information carrying medium applied to the printing plate and after the Printing process replaced.

From the document DE 41 23 959 C1 is a method for the regeneration of a for offset printing suitable printing form known. The regeneration of the printing plate includes the Removal of the imaging on the printing form and hydrophilization of the surface of the Printing form. According to this document, the regeneration takes place in that on the Printing form applied an ionized process gas by means of a loading device with a reactive deletion of the imaging and the simultaneous hydrophilization in a process step is made. The resulting volatile reaction products are removed by a suction device.

A disadvantage of this regeneration device is the high technical complexity required for the Regeneration of the printing plates must be operated.

From US 4,718,340 a printing method is known in which on a printing plate or on the surface of a printing forme cylinder is applied a water-friendly layer. This in turn is covered with a color-friendly layer. To create the print image, the color-friendly layer is partially detached by an ablation laser, so that printing and non-printing areas arise.

To regenerate the printing form, the color-friendly, the image information bearing Layer, or both layers removed. This happens in one of the variants shown the same ablation laser used to generate the image information on the printing form has been used.

A disadvantage of this solution is that the removal of the printed image or the layers very time consuming.

Based on this prior art, it is an object of the invention to provide a method and to provide a device by which the layer carrying the image information rapidly and safely removed from the surface of the printing cylinder or from the printing plate.

According to the invention the object is achieved by the features of claim 1.

The invention has the advantage that now the process of removing the image information in a much shorter time.

Figur 1:

Schematische Darstellung eines Druckwerkes mit einem Laserkopf zum Übertragen und Löschen der Bildinformation

Figur 2:

Schematische Darstellung eines Druckwerkes mit einem Laserkopf zum Übertragen und Löschen der Bildinformation und einem per Lichtleitkabel verbundenen zusätzlichen Laser

Figur 3:

Schematische Darstellung eines Druckwerkes mit einem Laserkopf zum Übertragen und Löschen der Bildinformation und einem über ein Spiegelsystem angekoppelten zusätzlichen Laser

Reference to an exemplary embodiment, the invention will be explained in more detail below. The corresponding drawings have the following meaning:

FIG. 1:

Schematic representation of a printing unit with a laser head for transmitting and erasing the image information

FIG. 2:

Schematic representation of a printing unit with a laser head for transmitting and erasing the image information and an additional laser connected by optical cable

FIG. 3:

Schematic representation of a printing unit with a laser head for transmitting and erasing the image information and a coupled via a mirror system additional laser

FIG. 1 shows a printing unit 1 of a multicolour sheet-fed rotary printing press. The printing unit 1 contains, as a sheet-guiding cylinder, a printing cylinder 2 and a transfer cylinder 3 and as a print image transferring cylinder a printing form cylinder 4 and a Rubber cylinder 5.

Each printing form cylinder 4 is assigned an inking unit 6 and a dampening unit 7. On the Printing form cylinder 4 can also be clamped (not shown here printing plate).

The printing form cylinder 4 is a (not shown) mounted in the frame imaging device 8 assigned. This consists of a laser head 12, in which a laser 9 integrated is. The power of the laser 9 is controllable. It can be both solid state lasers and Gas discharge laser can be applied.

The inventive method is realized with this device as follows:

With the pressure off and the inking and dampening unit 6 off; 7 is going through one here Coating device, not shown, a medium on the surface of the printing forme cylinder 4 or - if working with a printing plate - this medium on the surface the pressure plate applied. As a result, a coating 11 is formed. This coating consists in the embodiment of a polymer.

The prepared after application of the medium printing form cylinder 4 can now be imaged by the imaging device 8.

In this case, in a computer, not shown, data for the printing process in general prepared manner known and supplied to the imaging device 8. The rotation speed the printing form cylinder 4 is connected to the movement of the imaging device 8 synchronized. As a result of the imaging process, the surface of the Coating 11 subjected to image information and at the printing sites the Polymer hardened by the laser beam, so that printing and non-printing places arise. The non - printing areas must be replaced by a suitable device Unpolymerized material can be freed.

Subsequently, the printing process is completed. After printing, the artwork will be taken of the printing form cylinder 4 deleted. This is also done by the imaging device 8, which then works as an ablation device and the coating 11 detaches from the surface of the plate cylinder or from the printing plate.

During the erasing process, the intensity of the laser beam of the imaging device 8 increases and thus increased the effect on the surface to be treated. The happens according to the invention by increasing the power of the laser 9 by the electrical operating parameters are changed.

An advantageous embodiment of the invention is the diameter of the laser beam to increase by changing the focus. Thus the reliability of the Image resolution can be increased.

The imaging of the applied coating 11 and the image removal take place with rotating It is advantageous to the printing form cylinder 4 when Imaging Disconnect from the drive and delete. The printing forme cylinder has in this case for the Imaging and image removal a separate drive.

FIG. 2 shows a further exemplary embodiment of the invention. The construction of the Printing unit 1 is analogous to the embodiment shown above. The imaging device also consists of a laser head 12, which is associated with a laser 9. The laser 9 is connected via a light guide cable with a second laser 10. In another (here not shown) design, several lasers are assigned via fiber optic cable 14.

The process according to the invention is realized here as follows:

The coating and the imaging are carried out analogously to the above-mentioned embodiment. To detach the coating is in the laser head 12 via the optical fiber 14th the light of the second laser 10 or further laser supplied and thus the intensity of the Increased effect on the surface to be treated.

FIG. 2 shows a further exemplary embodiment of the invention. The construction of the Printing unit 1 is analogous to the embodiment shown above. The imaging device also consists of a laser head 12, which is associated with a laser 9. One or a plurality of further lasers 10 'are arranged in the vicinity of the laser 9 and can, if necessary, their Supply energy via a mirror system 13 to the laser 9.

The process according to the invention is realized here as follows:

The coating and the imaging are carried out analogously to the above-mentioned embodiment. To detach the coating, the light beam of the second laser 10 'over the mirror system 13 is supplied to the laser head 12 so that the intensity of the effect is enhanced and the coating can be peeled off within a very short time.

List of used reference numbers

1

printing unit

2

pressure cylinder

3

Transfer cylinder

4

Plate cylinder

5

rubber cylinder

6

inking

7

dampening

8th

imaging

9

laser

10; 10 '

second laser

11

layer

12

laser head

13

Mirror System

14

optical cable

Claims (5)

1. Method of treating printing formes or printing forme cylinders, which can be imaged again, in printing machines, wherein

   a coating (11), which can be imaged, is applied to the surface to be treated,

   this coating (11) is, for producing an image information, acted on by energy by way of an imaging device (8) equipped with a laser (9),

   the printing process is initiated with the imaged printing forme and

   after printing has taken place the imaging is erased from the printing forme cylinder, wherein

   the imaging device (8) is also used for removing the coating (11) in that

   during removal of the coating by the imaging device (8) the intensity of the laser for action on the surface to be treated is increased.
2. Method of treating printing formes or printing forme cylinders, which can be imaged again, in printing machines according to claim 1, characterised in that in the imaging by the energy feed into the coating (11) the image-carrying elements are polymerised.
3. Method of treating printing formes or printing forme cylinders, which can be imaged again, in printing machines according to claim 1, characterised in that for power amplification of the imaging device (9) during detaching of the coating (11) the power of the laser is increased to the requisite value.
4. Method of treating printing formes or printing forme cylinders, which can be imaged again, in printing machines according to claim 1, characterised in that for power amplification of the imaging device (8) during detaching of the coating (11) at least one further laser (10, 10') is switched on.
5. Method of treating printing formes or printing forme cylinders, which can be imaged again, in printing machines according to claims 1 to 4, characterised in that the diameter of the laser beam is enlarged during the erasing process.

Images