Laser cutting method

1. A method for cutting a workpiece, said method comprising:

a step of laser cutting at least a first aperture in a first metal plate in the presence of a second metal plate placed parallel to and a short distance from the first plate and having a second aperture, the outline of which is in line with the outline of the first aperture to be cut, wherein a third plate forming a protective device, of defined thickness and having a third aperture whose outline is inwardly offset with respect to the outline of the second aperture, is present between the first and second plates during laser cutting.

2. The method as claimed in the preceding claim, wherein the first plate is made of a nickel-based alloy.

3. The method as claimed in claim 1 or 2 , wherein the distance between the first and second plates is less than 15 mm.

4. The method as claimed in claim 1 , wherein the third plate forming a protective device is made of an aluminum-based alloy with a thickness between 0.5 and 1.5 mm.

5. The method as claimed in claim 1 , wherein the offset between the outline of the third aperture in the protective device relative to the outline of the second aperture in the second plate is less than 0.5 mm.

6. The method as claimed in claim 5 , wherein the offset is between 0.2 and 0.3 mm.

7. The method as claimed in claim 1 , wherein the first and second plates are, respectively, an inner shell and an outer shell that are mounted coaxially inside a turbomachine casing.

8. The method as claimed in claim 7 , wherein the apertures made in the shells form housings for distributor vanes.