PROCESS FOR MANUFACTURING A METERING ROLL ESPECIALLY USABLE FOR FLEXOGRAPHIC PRINTING

Description

Technical Field

[0001] The present invention concerns a process for manufacturing a metering roll especially usable in flexographic printing presses, in varnish stations for offset presses and/or in short ink train dry offset presses for example, comprising a central cylindrical core and at least one layer of a hard material peripheral coating.

Background Art

[0002] The metering rolls, so-called "anilox rolls" are widely used to bring a metered quantity of ink to the plate roll with which it is in contact. The surface layer of the peripheral coating is usually ceramic or metal or a metallic component or alloy, as a metal oxide or carbonate for example. This layer is engraved, mainly by use of a laser beam.

[0003] For a new use of an existing used anilox roll, it has to be refurbished and the prior art technology to refurbish such an anilox roll consists in the following steps:

(a) A first step consisting in removing the old coating by mechanical methods, like grinding, blasting. This operation is complicated and time-consuming because the coating is made of a hard material not easy to remove.

(b) A second step consisting in applying a new coating on the turned or grinded and corundum-blasted surface of the anilox roll.

(c) A third step of grinding and polishing the new coating with diamond bands or similar to obtain a perfectly cylindrical and smooth surface.

(d) A fourth step of engraving the new coating with a laser or suitable mechanical tools.

[0004] This technology is very cost-effective.

[0005] The closest prior art is disclosed in the British patent application GB-A-2423053 which describes a process for manufacturing a meetering roll, especially usable in flexographic printing processes, comprising a central cylindrical core and at least one layer of a hard material peripheral coating, wherein the process comprises at least a step of engraving the peripheral coating of said hard material.

Disclosure of Invention

[0006] The process of the invention offers a new technology permitting to refurbish the anilox rolls much more easily, more quickly and at lower costs.

[0007] This invention is preferably based on an idea of improving the usual process for manufacturing a metering roll, so-called "anilox roll". It is also based on the aim to reduce the number of steps and simplify the operations and consequently decrease the cost to refurbish used metering rolls.

[0008] Therefore, the process of the present invention such as defined in the preamble is characterized in that it comprises at least a first step of melting superficially at least partially the hard material coating, a second step of solidifying said melted hard material, and a third step of engraving the said solidified layer of hard material.

[0009] According to a preferred realization the first step consists in melting a superficial layer of a rough coating of hard material located on the cylindrical core of a new metering roll to provide a flat smooth surface without any unevenness ready to be engraved.

[0010] According to another realization the first step consists in melting at least partially the hard material coating of a used metering roll at a depth sufficient to remove any unevenness of the surface to provide a flat smooth surface without any unevenness ready to be engraved.

[0011] The first step may be performed preferably by a laser beam. According to an alternative solution, the first step may be performed by a plasma torch.

[0012] Said hard material coating obtained during the second step comprises preferably at least a ceramic, at least a metal or at least a metallic component.

[0013] The third step is preferably performed with at least one laser beam, or a similar technology.

Brief Description of Drawings

[0014] The invention will now be described, by way of an example, with reference to the accompanying drawings, in which :

Figure 1 is a cut view showing partially the surface of an anilox roll to be refurbished according to the process of the present invention,

Figure 2 is a similar view as in figure 1, showing a layer of the melted hard material according to one step of the process of the present invention, and

Figure 3 is a similar view as in figures 1 and 2, showing a new layer of the hard material engraved according to a further step of the process of the present invention.

Mode for Carrying Out the Invention

[0015] The process of the invention may be used as well for manufacturing new metering rolls as for refurbishing used metering or so-called anilox rolls. For the first application, the process permits to modify the properties of the peripheral coating, especially the surface tension, the porosity, the hardness. For the second application the process permits to reduce the costs of a life extension of the used metering rolls. Further it is also possible to modify the properties of the coating like for new rolls.

[0016] According to the process of the invention, the steps for refurbishing used anilox rolls are the following :

(1) The existing hard material surface coating in ceramic, hard metal or hard metal components is melted to a depth sufficient to remove the engraving. This operation may be done with a focused laser beam.

(2) The melted hard material solidifies and forms a flat surface free of engraving.

(3) The hard material coating can be engraved again with a laser beam within the re-melted zone.

[0017] Figure 1 shows partially the surface of a so-called anilox roll 10 to be refurbished according to the process of the invention. It comprises a central cylindrical core 11 and at least one layer 12 of a hard material peripheral coating. In the drawing only one layer is shown, but the coating could be formed of a plurality of different layers having each another composition and/or properties. The outer part 13 of the layer 12 is engraved, preferably by use of a laser beam (not shown).

[0018] Figure 2 shows the anilox roll 10 with a part 14 of the coating of hard material 12, including the engraved outer part 13, melted by a laser beam 15, on a thickness that is deeper than the depth of the existing textured layer 13.

[0019] Figure 3 shows the anilox roll 10 having a melted and solidified layer 16 of a hard material recovering the coating 12 and being provided with a new engraving 17 made by at least one laser beam.

[0020] This process according to the invention permits to withdraw the steps (a) to (c) of the prior art technology commonly used for refurbishing anilox rolls.

[0021] Relating to the manufacture of new metering rolls according to the usual process the hard material structured surface is realized in at least three steps:

• a first step consisting in applying a rough layer of a hard material,
• a second step consisting in grinding and polishing the surface of the rough layer of hard material, i.e. by diamond bands, and
• a third step of engraving the polished surface with a laser beam.

[0022] According to the process of the invention, the grinding and polishing as a second step should be replaced by laser melting and smoothening of the hard material that solidifies and forms a smooth and flat surface. In any case, the steps of grinding and polishing with diamond bands or similar will be saved. The physical properties, i.e. the mechanical resistance or other specifications may be adapted to special applications of the metering rolls by choosing the appropriate hard material and laser parameter settings. Finally the densified and smoothened hard material coating can be engraved with a laser beam.

Claims

1. A process for manufacturing a metering roll especially usable in flexographic printing presses, in varnish stations for offset presses and/or in short ink train dry offset presses for example, comprising a central cylindrical core (11) and at least one layer (12) of a hard material peripheral coating, characterized in that it comprises at least a first step of melting superficially at least partially the hard material coating, a second step of solidifying the melted hard material, and a third step of engraving the solidified layer of said hard material.

2. A process according to claim 1, characterized in that the first step consists in melting a superficial layer of a rough coating of hard material on the central cylindrical core of a new metering roll to realize a flat smooth surface without any unevenness ready to be engraved.

3. A process according to claim 1, characterized in that the first step consists in melting at least partially the hard material coating of a used metering roll at a depth sufficient to remove any unevenness of the surface to realize a flat smooth surface without any unevenness ready to be engraved.

4. A process according to any of the claim 1 to 3, characterized in that the first step is performed by at least one laser beam.

5. A process according to any of the claims 1 to 3, characterized in that the first step is performed by at least one plasma torch.

6. A process according to claim 1, characterized in that said hard material coating obtained during the second step comprises at least a ceramic.

7. A process according to claim 1, characterized in that said hard material coating obtained during the second step comprises at least a metal.

8. A process according to claim 1, characterized in that said hard material coating obtained during the second step comprises at least a metallic component.

9. A process according to claim 1, characterized in that the engraving during the third step is performed with at least one laser beam.

Ansprüche

1. Verfahren zum Herstellen einer Dosierwalze, die insbesondere zum Beispiel bei Flexodruckmaschinen, in Lackierstationen für Offsetdruckmaschinen und/oder in Kurzfarbwerk-Trockenoffsetdruckmaschinen verwendbar ist, mit einem zentralen zylindrischen Kern (11) und wenigstens einer Schicht (12) aus einer Umfangsbeschichtung aus einem harten Material,
dadurch gekennzeichnet, dass
es wenigstens einen ersten Schritt des zumindest teilweisen oberflächlichen Schmelzens der Beschichtung aus hartem Material und einen zweiten Schritt des Erstarrens des geschmolzenen harten Materials und einen dritten Schritt des Einschneidens bzw. Gravierens der erstarrten Schicht des harten Materials aufweist.

2. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
der erste Schritt aus dem Schmelzen einer oberflächlichen Schicht einer rohen Beschichtung aus einem harten Material auf dem zentralen, zylindrischen Kern einer neuen Dosierwalze besteht, um eine flache, glatte Fläche ohne jegliche Unebenheit zu bilden, die bereit ist, graviert zu werden.

3. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
der erste Schritt aus dem zumindest teilweisen Schmelzen der Beschichtung aus einem harten Material einer gebrauchten Dosierwalze in einer Tiefe besteht, die ausreichend ist, um jegliche Unebenheit der Oberfläche zu entfernen, um einen flache, glatte Fläche ohne jegliche Unebenheit zu bilden, die bereit ist, graviert zu werden.

4. Verfahren nach einem der Ansprüche 1 bis 3,
dadurch gekennzeichnet, dass
der erste Schritt mittels wenigstens eines Laserstrahls durchgeführt wird.

5. Verfahren nach einem der Ansprüche 1 bis 3,
dadurch gekennzeichnet, dass
der erste Schritt mittels wenigstens eines Plasmabrenners durchgeführt wird.

6. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
die während des zweiten Schritts erlangte Beschichtung aus dem harten Material zumindest eine Keramik aufweist.

7. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
die während des zweiten Schritts erlangte Beschichtung aus dem harten Material zumindest ein Metall aufweist.

8. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
die während des zweiten Schritts erlangte Beschichtung aus dem harten Material zumindest eine metallische Komponente aufweist.

9. Verfahren nach Anspruch 1,
dadurch gekennzeichnet, dass
das Gravieren während des dritten Schritts mit wenigstens einem Laserstrahl durchgeführt wird.

Revendications

1. Procédé de fabrication d'un rouleau de dosage en particulier utilisable dans des presses d'impression flexographique, dans les postes de vernis pour presses offset et/ou des presses offset à encre sèche, par exemple, comprenant un noyau central cylindrique (11) et au moins une couche (12) d'un revêtement périphérique en matériau dur, caractérisé en ce qu'il comprend au moins une première étape consistant à faire fondre au moins superficiellement et au moins partiellement le matériau du revêtement dur, une deuxième étape consistant à solidifier le matériau dur fondu, et une troisième étape consistant à graver la couche solidifiée dudit matériau dur.

2. Procédé selon la revendication 1, caractérisé en ce que la première étape consiste à faire fondre une couche superficielle d'un revêtement rugueux de matériau dur sur le noyau cylindrique central d'un nouveau rouleau de dosage, pour réaliser une surface plane et lisse, sans irrégularités, prête à être gravée.

3. Procédé selon la revendication 1, caractérisé en ce que la première étape consiste à faire fondre au moins partiellement le revêtement en matériau dur d'un rouleau de dosage usagé sur une profondeur suffisante pour éliminer les irrégularités de la surface, pour réaliser une surface plane et lisse, sans aucune irrégularité, prêt à être gravé.

4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que la première étape est réalisée par au moins un faisceau laser.

5. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que la première étape est réalisée par au moins une torche à plasma.

6. Procédé selon la revendication 1, caractérisé en ce que ledit revêtement en matériau dur obtenu lors de la deuxième étape comprend au moins une céramique.

7. Procédé selon la revendication 1, caractérisé en ce que ledit revêtement en matériau dur obtenu lors de la deuxième étape comprend au moins un métal.

8. Procédé selon la revendication 1, caractérisé en ce que ledit revêtement en matériau dur obtenu lors de la deuxième étape comprend au moins un composant métallique.

9. Procédé selon la revendication 1, caractérisé en ce que la gravure effectuée au cours de la troisième étape est réalisée avec au moins un faisceau laser.

Drawing