Method for manufacturing and regenerating a functional surface of an anilox sleeve or anilox roller for a printing machine and anilox sleeve or anilox roller with such functional surface

Abstract

A method for manufacturing and regenerating a functional surface of an anilox sleeve or anilox roller for a printing machine with a coating protecting against wear and corrosion. The anilox sleeve is preferably made out of a lightweight plastic on which an intermediate layer is applied and has a metal tube located above the intermediate layer. During a first phase, the worn engraving and the old layer are ground off from the cylindrical surface of the anilox sleeve, that is to say from the metal tube, and a coating, a carbidic tungsten carbide-cobalt-chromium layer (WCCoCr) is subsequently applied. This carbidic layer is applied by a high-speed flame spraying (HVOF) process and subsequently functionalized by laser.

Claims

1. A method of either manufacturing or regenerating a functional layer of an anilox sleeve or an anilox roller for a printing machine, the method comprising: applying a coating of a coating material protecting, against wear and corrosion, by a high-speed flame spraying (HVOF) on a cylindrical surface of the anilox sleeve or the anilox roller, the coating forming the functional layer, manufacturing the coating material from a cermet made of a mixture of a hard phase and a metallic binder, making the hard phase of the coating material from tungsten carbide (Wc), making the metallic binder from at lease one of cobalt (Co), chromium (Cr) and nickel, and structuring a surface topography of the coating by local volatilization of the coating material under the action of an ytterbium fiber laser in such a way that the use of the anilox sleeve or the anilox roller allows supplying a defined reproducible ink volume to the printing mechanism of the printing machine.

2. The method according to claim 1, further comprising making the metallic binder from cobalt (Co) and chromium (Cr).

3. The method according to claim 1, further comprising using a weight proportion of the hard phase between 75 and 92 percent.

4. The method according to claim 1, further comprising using a weight proportion of the hard phase between 85 and 90 percent.

5. The method according to claim 1, further comprising using a weight of the metallic binder which is at least 10 percent.

6. The method according to claim 1, further comprising using a weight of the metallic binder which is between 12 to 18 percent.

7. The method according to claim 1, further comprising using a thickness of the functional layer of between 50 to 200 micrometers.

8. The method according to claim 1, further comprising using a thickness of the functional layer of between 80 to 120 micrometers.

9. The method according to claim 1, further comprising applying a metallic adhesion layer prior to the application of the the coating forming the functional layer.

10. The method according to claim 9, further comprising using at least one of nickel, chromium and molybdenum as a main constituent of the adhesion layer.

11. The method according to claim 9, further comprising using a thickness of the adhesion layer of between 50 to 300 micrometers.

12. The method according to claim 9, further comprising using a thickness of the adhesion layer of between 100 to 150 micrometers.

13. The method according to claim 1, further comprising using a pulsed ytterbium fiber laser as the ytterbium fiber laser.

14. The method according to claim 1, further comprising applying the coating to the anilox sleeve, and making the anilox sleeve from a fiber-reinforced plastic core, the fibers are either glass fibers or carbon fibers, on which an intermediate layer is applied, which connects the fiber-reinforced plastic core of the anilox sleeve with an outer enveloping tube formed out of either aluminum or an aluminum alloy.

15. The method according to claim 1, further comprising removing a worn or a damaged functional layer and adhesion layer from the cylindrical surface of the anilox roller or the anilox sleeve by mechanical machining, and reconditioning the anilox roller or the anilox sleeve by a subsequent new coating and laser processing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following drawings illustrate an embodiment example of the described method:

(2) FIG. 1 shows a cross-section of the surface layer of the sleeve according to the invention, and

(3) FIG. 2 is a 3D view of the sleeve according to the invention.

PRACTICAL APPLICATION OF THE INVENTION

(4) Tests have shown that the technical prerequisites are met for applying an engravable WCCoCr coating with the help of a HVOP process on a light anilox sleeve.

(5) For the manufacture or the reconditioning of an anilox sleeve/anilox roller, the surfaces (rollers: steel, sleeves: aluminum) must be suitably prepared (ground or finely turned). Finally, a carbidic WCCoCr layer is applied on the adhesion base by HVOF.

(6) The advantages of this coating, which can be if necessary provided with an adhesion base (HG) in case of particular stress, lie in the changed surface energy of the engraving, which results in improved ink acceptance and transfer. Furthermore, this coating ensures lower wear and improved cleaning behavior of the engraved surface. This moreover allows using less aggressive cleaners, which has a positive impact on the environment and on safety at work. In addition, as the WCCo layer has a lower porosity, the risk of undercorrosion is practically excluded. This leads overall to significantly lower downtime of the equipment.

(7) As almost all new printing machines used in packaging printing are equipped with anilox sleeves/rollers, the invention thus combines all previously described advantages of the WCCoCr layer with the advantages of the anilox sleeve/roller system:

(8) short setup times, long service life, high quality, high cost-efficiency.