An axial turbine engine comprises, in a manner known in the art, an external wall allowing an annular flow to be guided. Moreover, this wall can support a plurality of rows of stator blades, allowing the flow to be deviated. The external wall can be realized in the form of a plurality of shrouds forming axial sections of the external wall. These sections are assembled axially and fixed to one another to form the continuous wall.
In the context of a low-pressure compressor, these shrouds may play a structuring part, since they allow the separation spout to be connected to the intermediate casing of the turbine engine. They each support a row of blades.
The stator blades are generally welded onto each shroud so as to form an annular row. This method of fixing allows a robust, rigid one-piece assembly to be created. This architecture furthermore allows the number of interfaces between the mechanical elements to be reduced.
Document U.S. Pat. No. 6,321,448 B1 discloses a method of producing an external turbine engine blade. The method comprises a succession of several stages, including the cutting of a plate such that the dimensions thereof correspond to the outer sides of the external shroud of the casing, bending of the cut plate to form a tube, laser-cutting of the plate to create openings according to the blade profiles, then insertion and welding of the blades in their openings for final fixing. This method allows the time taken to position and adjust the blades in the tube forming the casing to be reduced. However, this method requires accurate cuts to be made, the existence of which weakens the casing. The blade welding operation is expensive, since it has to be carried out in a vacuum. This type of welding increases the preparation and processing time of the projections. The welds at the level of the openings reduce the stator's fatigue strength.
USPTO Backgrounds
USPTO Backgrounds