EP1179423A2 - Method and device for manufacturing a printing form in a printing machine - Google Patents

Abstract

The invention relates to a method for generating a printing machine printing form carrying a print image information on a printing form cylinder in a printing press. The object of the invention is to provide a method for producing an erasable printing form on the printing form cylinder in a printing press with little effort and a long service life. According to the invention the object is achieved in that the printing form cylinder has an oxidizable surface, the oxidizable surface is oxidized image-bearing, is printed with the resulting printing form and after the printing process the oxidized surface is converted back into the oxidizable surface by reduction. <IMAGE>

Description

The invention relates to a method for generating a print image information Printing machine printing form on a printing form cylinder in a printing press.

It is a method of making a printing form for planographic printing machines, in particular for offset printing machines with dampening system, with hydrophobic, which absorb the printing inks Image areas and hydrophilic areas affecting water affinity in one Printing machine known DE 4119111 A1. At least one is attached to a reservoir connected nozzle small droplets of an oleophilic, water-resistant coating medium generated in dot or matrix form and image-appropriate on parts of a hydrophilic Printing cylinder surface applied, the nozzle in the line direction and the printing cylinder vertically shifted, digital image information from a central control unit an information carrier and the control signals via a transmission unit and a control unit of the nozzle and the printing form cylinder.

Furthermore, the xerox copying process is generally known. With this copying process a latent image is generated on a semiconductor drum, this image by means of a powder Transfer the toner onto the paper sheet and erase the latent image. In printing machines this method is not applicable.

The object of the invention is to provide a method for generating an erasable Printing form on the printing form cylinder in a printing press with little effort and long service life.

According to the invention, the object is achieved by the characterizing part of the first claim, expedient configurations are disclosed in the subclaims.

The solution according to the invention is explained in more detail below using an exemplary embodiment.

Fig. 1

Druckformzylinder mit Reduktionseinrichtung

Fig. 2

Druckformzylinder mit Oxydiereinrichtung

The drawing shows in:

Fig. 1

Printing form cylinder with reduction device

Fig. 2

Printing form cylinder with oxidizing device

1 shows a printing form cylinder of a printing press. The printing form cylinder 1 is equipped with an oxidizable surface 2, the oxidizable surface 2 expediently having hydrophilic properties.
The oxidizable surface 2 is provided with oxidized image-bearing areas 3 from a previous print job, the oxidized image-bearing areas being hydrophobic.

Before 1 new image-bearing points can be applied to the printing cylinder to remove the oxidized image-bearing areas 3 of the previous print job. The distance the image-bearing points 3 of the previous print job is done with a Reduction device 4 associated with printing form cylinder 1, this reduction device 4 works on a laser basis. The reduction device 4 is across the width of the printing form cylinder 1 arranged traversing or extends over the entire width of the printing cylinder 1.

Reduction means that an endothermic reaction takes place, in which a compound contains oxygen is withdrawn, d. H. Metal ions receive their valence electrons and thus the metallic character back.

2 shows the process step oxidation of the new image-bearing sites of the oxidizable surface 2. The new image-bearing points of a new print job are oxidized by means of an oxidation device 6.
Oxidation means that an exothermic reaction with oxygen takes place, whereby valence electrons are released and the metal character is lost, ie the oxidized points 5 are made receptive to the printing ink to be applied later. The oxidation device 6 is connected to a storage device (not shown) for the digital matrix of the image-bearing points.
The oxidation device 6, like the reduction device 4, is arranged traversing or extending over the entire width of the printing form cylinder 1.

REFERENCE NUMBERS

1

Plate cylinder

2

Oxidized surface

3

image-bearing body (old print job)

4

reducer

5

oxidized area

6

oxidation means

Claims (3)

Method for producing a printing form carrying a print image information on a printing form cylinder in a printing press, characterized in that the printing form cylinder (1) has an oxidizable surface (2), oxidizes the oxidizable surface image-bearing, printed with the resulting printing form and, after the printing process, the oxidized surface is converted back into the oxidizable surface by reduction. Method for producing a printing form carrying a print image information on a printing form cylinder in a printing press according to claim 1, characterized in that in the phase of oxidation the object to be oxidized is supplied with oxygen or a medium which releases oxygen under the influence of energy. Method for producing a printing form carrying a print image information on a printing form cylinder in a printing machine according to claim 1, characterized in that in the phase of reduction the medium to be reduced is supplied with a medium which absorbs oxygen under the influence of energy.

Images