Method of removing coating from a surface of a wheel

1. A method for removing a coating ( 9 ) on a surface of a wheel ( 1 ), the wheel ( 1 ) provided with screw channels ( 6 ) and with a central opening ( 8 ), each of the screw channels ( 6 ) and the central opening ( 8 ) is delimited by an area ( 7 ) from which the coating is to be removed, each of the areas ( 7 ) extends annularly around one of the screw channels ( 6 ) or around the central opening ( 8 ), the method being implemented using a laser beam ( 22 ) generated by a laser source ( 12 ), the method comprising the steps of:

a) positioning an extraction opening of an extractor ( 18 ) directly beneath a center of one of the screw channels ( 6 ) or the central opening ( 8 ) surrounded by the area ( 7 ) from which the coating is to be removed;

b) removing the coating from the area ( 7 ) by moving the laser beam over the area ( 7 ) from which the coating is to be removed, without masking the area ( 7 ) from which the coating is to be removed;

c) extracting with the extractor gases and particles produced during the step of removing the coating directly through one of the screw channels ( 6 ) or the central opening ( 8 ); and

d) repeating steps a) through c) and removing the coating from each of the screw channels ( 6 ) of the wheel ( 1 ) and the central opening ( 8 ) from the areas ( 7 ) surrounding the screw channels ( 6 ) and the central opening ( 8 ).

2. The method according to claim 1 , wherein the wheel ( 1 ) is fixed, wherein positions of the screw channels ( 6 ) and/or of the central opening ( 8 ) are automatically recorded, wherein the areas ( 7 ) from which the coating is to be removed are automatically defined on the basis of the recorded positions and the laser beam is correspondingly moved, and wherein fixing of the wheel ( 1 ) takes place such as to center the wheel ( 1 ).

3. The method according to claim 1 , wherein the laser beam is moved in a spiral shape over the area ( 7 ) from which the coating is to be removed.

4. The method according to claim 1 , characterised in that at least two coating removal stations ( 10 ) are provided for the implementation of the method, which stations share a single laser source ( 12 ).

5. The method according to claim 1 , including the steps of:

positioning the extraction opening of the extraction device ( 18 ) directly beneath a center of one of the screw channels ( 6 );

extracting with the extraction device gases and particles produced during the step of removing the coating directly through the associated one of the screw channels ( 6 ); and

repeating steps a) through c) and removing the coating from each of the screw channels ( 6 ) of the wheel ( 1 ) from the areas ( 7 ) surrounding the screw channels ( 6 ).

6. The method according to claim 1 , wherein a fibre laser or an Nd:YAG laser in a continuous wave mode or in a pulsed mode is used as the laser source ( 12 ), and wherein the laser beam being in the wavelength range of 1 to 1.1 μm.

7. The method according to claim 6 , wherein the wheel ( 1 ) is fixed, wherein positions of the screw channels ( 6 ) and/or of the central opening are automatically recorded, wherein the areas ( 7 ) from which the coating is to be removed are automatically defined on the basis of the recorded positions and the laser beam is correspondingly moved, and wherein fixing of the wheel ( 1 ) takes place such as to center the wheel ( 1 ).

8. The method according to claim 1 , characterised in that wherein the gases and particles that are produced while removing the coating are directly extracted.

9. The method according to claim 8 , wherein a direct extraction of the gases and particles takes place through the one of the screw channels ( 6 ).

10. The method according to claim 1 , characterised in that the coating is additionally removed from an inner wall of at least one screw channel ( 6 ).

11. The method according to claim 10 , characterised in that while the coating is being removed from the inner wall of a screw channel ( 6 ), the laser beam ( 6 ) is directed from a rotating mirror ( 26 ) positioned within the screw channel ( 6 ) onto the inner wall.

12. The method according to claim 1 , wherein the laser beam is moved by a scanner ( 13 ) over the at least one area ( 7 ) of the surface from which the coating is to be removed.

13. The method according to claim 12 , wherein a fibre laser or an Nd:YAG laser in a continuous wave mode or in a pulsed mode is used as the laser source ( 12 ), and wherein the laser beam is in the wavelength range of 1 to 1.1 μm.

14. The method according to claim 12 , wherein the wheel ( 1 ) is fixed, wherein positions of the screw channels ( 6 ) and/or of the central opening are automatically recorded, wherein the areas ( 7 ) from which the coating is to be removed are automatically defined on the basis of the recorded positions and the laser beam is correspondingly moved, and wherein fixing of the wheel ( 1 ) takes place such as to center the wheel ( 1 ).

15. The method according to claim 1 , wherein a CO 2 laser is used as the laser source ( 12 ), and wherein the laser beam being in the wavelength range of 9 to 11 μm.

16. The method according to claim 15 , wherein the wheel ( 1 ) is fixed, wherein positions of the screw channels ( 6 ) and/or of the central opening are automatically recorded, wherein the areas ( 7 ) from which the coating is to be removed are automatically defined on the basis of the recorded positions and the laser beam is correspondingly moved, and wherein fixing of the wheel ( 1 ) takes place such as to center the wheel ( 1 ).

17. The method according to claim 15 , wherein the CO 2 laser is operated in a continuous wave mode.

18. The method according to claim 17 , wherein the wheel ( 1 ) is fixed, wherein positions of the screw channels ( 6 ) and/or of the central opening are automatically recorded, wherein the areas ( 7 ) from which the coating is to be removed are automatically defined on the basis of the recorded positions and the laser beam is correspondingly moved, and wherein fixing of the wheel ( 1 ) takes place such as to center the wheel ( 1 ).