EP1386732B1 - Method and device for producing a printing form of a rotary printing machine - Google Patents

Description

The invention relates to a method for producing a printing forme for a rotary printing machine by imagewise controlled coating a surface of a printing forme cylinder with image-bearing elements, which are applied by means of one or more laser beams of a movable along the printing cylinder laser writing head on the surface of the rotating printing forme cylinder. Furthermore, the invention includes an apparatus for carrying out the method.

One possibility for producing a printing form and imagewise controlled coating of a surface of a printing forme cylinder by means of laser imaging is known from US Pat DE 44 30 555 known. Here, a band-shaped transport foil is moved by means of a belt transport mechanism between the surface of the printing cylinder and the imaging device along with the Bebilderungseinheit over the entire width of the printing forme cylinder, wherein the laser unit at each pixel initiates heat to the thermal transfer film and thus a selective transfer of the coating of the transfer ribbon on the Preformed cylinder performs. The transfer ribbon is consumed at locations that have already been transferred in an imaging and can not be reused.

Furthermore, a similar method including device from the DE 198 11 028 A1 As is known, in the embodiment of the previous embodiment, the transfer belt is used in a width which has a plurality of tracks next to one another for a plurality of images, so that a transfer belt has a longer service life than the solution known hitherto. The tape transport mechanism has a supply and a take-up reel so that the transfer tape is unwound from the supply reel and wound onto the take-up reel (or vice versa). When all traces of tape are used up, the machine must be stopped and a tape change made.

The object of the invention is therefore to provide a method and an apparatus for carrying out the method, in which / a larger number Bebilderungen can be done without changing the transfer element.

This object is achieved with a method mentioned in the introduction, in which a medium flow is generated in which constituents (particles) with the image-carrying properties are contained, in which the medium flow is passed continuously or pulsed through a machining gap between the laser writing head and the surface of the printing-plate cylinder, and at the laser beams penetrate the medium flow while components are deposited with image-bearing properties from the medium and formed on the printing form cylinder.

Immediately in the vicinity of the surface of the plate cylinder, a continuous or pulsed flow of a medium is generated, are contained in the particles or having image-bearing properties. This current can e.g. be passed through a supply or conduction system in the (treatment) gap between the surface of the printing forme cylinder and the laser writing head or passed therethrough. By means of laser beams, which impinge targeted on the image-bearing properties having constituents / particles in the medium flow, they are deflected from the medium flow and on the Bebilderungsfläche, which is formed by the surface of the printing forme cylinder itself, this surrounding pressure sleeve or a pressure plate mounted on this applied, shot or deposited on these. By releasing thermal energy in this process, the deposited particles can be melted onto the surface.

Alternatively, however, the deposited particles can also be sintered onto the (imaging) surface. By providing a continuous or pulsed medium stream within e.g. generated closed circuit and passed through the treatment gap, can be advantageously ensured a continuous imaging; it is not necessary to stop the machine and to provide it with optionally image-bearing transfer elements or the like.

According to one embodiment of the invention, the laser beam is substantially aligned preferably 90 ° to the medium flow to this.

According to one embodiment of the invention, the medium flow with the image-carrying properties is dust-shaped, that is, the image-bearing properties having components are dust particles. The medium flow is, for example, blown along a guide system whose sections run between the surface of the printing forme cylinder and the laser writing head and thus forms a dust curtain from which the image-bearing particles are shot onto the imaging surface by means of laser beams. Preferably, this image-carrying particles having medium flow is a per se known toner.

According to another embodiment of the invention, the medium flow is formed by a liquid which is passed through the treatment gap along a guide system. For example, the liquid medium flow along a guide made of laser-permeable material, which may be quartz glass, run, for example. Preferably, imaging according to this embodiment can be carried out by means of a method consisting of inkjet technology in conjunction with laser technology.

According to yet another embodiment of the invention, a gaseous medium flow can be generated. The gas stream passing through the treatment gap e.g. is blown, forms a kind of gas curtain, which is guided along an open or partially open control system. When using a gaseous medium, the properties of particular chemical compounds are exploited, for example, because they decompose due to thermal effects and thus solid bodies, such as e.g. Carbon as carbon black, release and applied to the surface to be imaged.

Furthermore, in conjunction with oxygen, the reduction can also be used for releasing solids which, for example, are melted or sintered onto a printing form cylinder as image-carrying elements.

Adhesion promoters may preferably be used in addition to the mentioned forms of the medium.

According to one embodiment of the invention, the medium flow can be generated mechanically by means of pressure. According to another embodiment, the medium flow can be generated electrostatically. Alternatively, however, the medium flow can also be generated electromechanically (piezoelectric effect).

Furthermore, the object is achieved with a device having a printing form cylinder, with a one or more laser emitting laser writing head, which is arranged displaceably along the printing forme cylinder, with a device in which a medium flow can be generated, in which components are contained with image-bearing properties, and by means of which the medium flow can be conducted through a machining gap between laser writing head and printing forme cylinder.

Within a rotary printing machine, in each case at least one printing unit is provided, to which at least one printing form cylinder is assigned. For imaging according to the invention of the printing plate cylinder or a seamless printing plate sleeve or optionally a printing plate, a laser writing head is designed to emit one or more laser beams, which is located in the immediate vicinity of the surface to be described. In order to describe the printing form cylinder over its entire width, the laser writing head along the printing forme cylinder is slidably disposed. One way of attaching and thus ensuring the necessary displaceability of the laser writing head is to attach it to a traverse, which runs along the printing forme cylinder. The printing form cylinder rotates under the laser writing head, so that the writing process is spiral.

Between the laser writing head and the surface to be printed, a treatment gap is formed, through which the medium flow flows with constituents / particles having image-carrying properties.

The medium flow generated mechanically, electrostatically or electromechanically within a device associated with the imaging device is guided in / by a medium circulation system such that the medium, irrespective of which state it is in, is deflected after passing through the treatment gap and again the treatment gap can be supplied. The medium circulation system, which may have a type of piping system, at least in the laser / imaging area sections which are on the one hand laser light-transmissive (eg of quartz glass) and on the other hand, the surface of the printing cylinder facing, open recesses, so that the liberated by means of laser beams (Mobilized) particles through these recesses out of the circulatory system and can be molded onto the surface.

Advantageously, this device has no imaging components that would have to be replaced, removed or the like within the printing unit, which means lower machine downtime compared to the prior art.

The device according to the invention will be explained in more detail with reference to an embodiment. In the figure, a printing form cylinder with a Bebilderungseinrichtung invention is shown at least schematically.

A rotary printing machine has at least one printing unit, which in turn is provided at least with a printing form cylinder 1. The printing form cylinder 1 itself, a printing form sleeve (not shown) enclosing this or a printing plate (not shown) mounted on the printing form cylinder 1 are provided within the machine with a coating (illustration), e.g. as an intermediate carrier for subsequent transfer to e.g. the substrate is suitable. A laser writing head 2, whose laser beams are aligned substantially perpendicularly relative to the longitudinal axis of the printing forme cylinder 1, is arranged in the immediate vicinity of the printing forme cylinder 1.

Furthermore, a device 3 is provided with a medium circulation system, by means of which a medium flow 4 is generated, wherein the medium is also guided through the machining gap between the laser writing head 2 and the printing form cylinder 1 in a wide range by means of a tube-like conduit system.

According to this embodiment, the medium circulation system of the device 3 has a forward branch 35 and a return branch 33. The forward branch 35 has at least sections 31, which are made of laser light-permeable material. In addition, the forward branch 35 additionally has sections 32, in particular in the area of imaging / laser irradiation (see in particular illustration A), which are provided with at least one recess 34, through which the particles accelerated by laser beams and carrying image-carrying properties from the medium Power 4 excreted / imposed and can be molded onto the surface of the plate cylinder 1.

The laser writing head 2 together with the device 3 can be arranged on eg a traverse (not shown) and moved in the longitudinal direction of the printing forme cylinder 1, so that the printing forme cylinder 1 can be described over its entire width.

LIST OF REFERENCE NUMBERS

1

Plate cylinder

2

Laser Stylus

3

Device with a medium circulation system

31

Section of the pre-load

32

Section of the pre-load

33

return branch

34

Recess in the forward branch

35

Vorlaufast

4

medium flow

Claims (16)

1. Method of producing a printing plate for a rotary printing machine by coating, which is controlled in accordance with image, of a surface of a printing plate cylinder with image-bearing elements, which are applied to the surface of the rotating printing plate cylinder by means of one or more laser jets of a laser writing head movable along the printing cylinder,

   - in which a medium flow, in which components with the image-bearing characteristics are contained is generated

   - in which the medium flow is guided in continuous or pulsed manner through a processing gap between laser writing head and surface of the printing plate cylinder and

   - in which the laser jets penetrate the medium flow and in that case components with image-bearing characteristics are separated out of the medium and formed onto the printing plate cylinder.
2. Method according to claim 1, in which the laser jet is oriented onto the medium flow at substantially 90° relative thereto.
3. Method according to one of claims 1 and 2, in which the medium flow contains dust particles.
4. Method according to claim 3, in which the medium flow is dust-like toner.
5. Method according to one of claims 1 and 2, in which medium flow is liquid.
6. Method according to one of claim 1 and 2, in which the medium flow is gaseous.
7. Method according to any one of claims 1 to 6, in which the components separated out of the medium flow are melted onto the printing plate cylinder.
8. Method according to any one of claims 1 to 6, in which the components separated out of the medium flow are sintered onto the printing plate cylinder.
9. Method according to any one of claims 1 to 8, in which the medium flow is produced mechanically.
10. Method according to any one of claims 1 to 8, in which the medium flow is produced electrostatically.
11. Method according to any one of claims 1 to 8, in which the medium flow is produced electromechanically.
12. Device for carrying out the method according to claim 1, comprising

    - a printing plate cylinder (1),

    - a laser writing head (2), which transmits one or more laser beams and which is arranged to be displaceable along the printing plate cylinder (1), and

    - a device (3) in which a medium flow (4) containing components with image-carrying characteristics can be produced and

    - by means of which the medium flow (4) can be conducted through a processing gap between laser writing head (2) and printing plate cylinder (1).
13. Device according to claim 12, in which the device (3) is constructed as a closed circuit medium system (33, 35) and the medium which has flowed through the processing gap can be fed again to the processing gap.
14. Device according to claim 12, in which the medium flowing through the processing gap forms a gas cloud.
15. Device according to claim 12 or 13, in which the medium flowing through the processing gap is formed as a dust cloud.
16. Device according to claim 12 or 13, in which the medium flowing through the processing gap is a liquid.

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