Doctor Beam

Abstract

A doctor beam for use in a printing unit, e.g. a flexographic printing unit, wherein the doctor beam has a front side with a U-shaped channel, wherein the doctor beam is made of metal and includes a surface coating produced by Plasma Electrolytic Oxidation (PEO), the surface coating at least covering the U-shaped channel, and wherein the doctor beam further includes a non-stick ceramic coating, whereby is achieved the possibility of using metal for making doctor beams without risking their degrading, neither due to chemical impact of the applied inks/lacquers/primers nor due to the destruction of the surface coating by cleaning liquids. The invention also concerns a method for treating the surface of a doctor beam and use of a doctor beam.

Claims

1. A doctor beam for use in a printing unit, e.g. a flexographic printing unit, wherein the doctor beam has a front side with a U-shaped channel, wherein the doctor beam is made of metal and includes a surface coating produced by plasma electrolytic oxidation (PEO), where the surface coating at least covers the U-shaped channel, and where the doctor beam further includes a non-stick ceramic coating at least covering the U-shaped channel.

2. A doctor beam according to claim 1, wherein the doctor beam is made of aluminium.

3. A doctor beam according to claim 1, wherein the surface coating produced by plasma electrolytic oxidation (PEO) has a thickness between 5 and 50 m.

4. A doctor beam according to claim 1, wherein the surface coating produced by plasma electrolytic oxidation (PEO) covers the entire doctor beam.

5. A doctor beam according to claim 1, wherein the ceramic coating has a thickness between 30 and 50 m.

6. A doctor beam according to claim 1, wherein the ceramic coating covers the entire surface of the doctor beam.

7. A method for surface treatment of a doctor beam according to claim 1 for use in a printing unit, e.g. a flexographic printing unit, wherein the method includes at least the following steps: A: the doctor beam is laid into an aqueous electrolyte; and B: a pulsating bipolar electric current is conducted through the electrolyte.

8. A method for surface treatment of a doctor blade according to claim 7, wherein the method further includes at least the following steps: C: a coating is applied the surface of the doctor beam; and D: the coating is cured at 250 C.

9. Use of a doctor beam according to claim 1 for use in a printing unit, e.g. a flexographic printing unit.

Description

DESCRIPTION OF THE DRAWING

[0037] The invention will now be explained more closely in the following by description of non-limiting embodiments with reference to the drawing, where:

[0038] FIG. 1 shows a schematic section through a doctor beam;

LIST OF DESIGNATIONS

[0039] 1 Doctor beam [0040] 2 front side [0041] 3 U-shaped channel [0042] 4 chamber [0043] 5 doctor blade [0044] 6 printing roller [0045] 7 plasma electrolytic oxidation [0046] 8 surface coating

DETAILED DESCRIPTION OF THE INVENTION

[0047] It appears on FIG. 1 that the doctor beam 1 has a front side 2 in which is formed a U-shaped channel 3. This U-shaped channel 3 forms a part of a chamber 4 which is further delimited by doctor blades 5 disposed at either side of the U-shaped channel 3, and by a printing roller 6. The delimited chamber 4 is used for the applied primer, ink or lacquer.

[0048] The doctor beam 1 has a surface that has gone through a plasma electrolytic oxidation 7 at least covering the U-shaped channel 3, but which in the shown embodiment extends along the whole front side 2 of the doctor beam.

[0049] The doctor beam 1 can have a surface additionally provided with a surface coating 8 which at least covers the U-shaped channel 3, but which in the shown embodiment also extends over the whole front side 2 of the doctor beam.