Method of making a wiper for a sealing labyrinth, and a thermomechanical part and a turbomachine including such a wiper

1. A method of making an annular wiper on a thermomechanical support for a sealing labyrinth, the method comprising:

a) providing a support that is circularly symmetrical about a longitudinal axis and that presents an annular base for a wiper;

b) providing a spray nozzle which moves relative to the support and a first source of a first powder material identical to the material of the support, and a second source of the second powder material that is harder than the first material, said first source and said second source being connected to the spray nozzle;

c) providing a laser source connected to an optical head which moves relative to the support to focus the laser beam on a point of the surface of the support;

d) aiming the optical head and the nozzle at a common point of the surface of the top of the base of the wiper;

e) activating the laser source and the sources of powder material so as to form a localized melt at said point, into which the powder material is injected, thereby forming a localized region of extra thickness;

f) aiming the optical head and the nozzle on another point of the surface of the top of the base adjacent to said localized region of extra thickness and returning to step e) until a layer has been formed over substantially the entire width of the top of the base; and

g) building at least a fraction of the projecting portion of the wiper by successively depositing layers that become narrower and narrower in the longitudinal direction on the top of the base, each layer being the result of performing steps d) to f), and comprising, at its both edges, an annular bead belonging to the coating of the tip of the wiper and constituted in the majority with the second material, and a zone filling a space circumscribed between the two annular beads and belonging to the core of the tip of the wiper, said zone being constituted in majority with the first material.

2. A method according to claim 1 , wherein steps d) to f) are performed until the entire surface of the top of the base has been coated in a layer, and wherein, during step g), the projecting portion of the wiper is built up by successively depositing layers that are narrower and narrower in the longitudinal direction over the entire surface of the top of the base, each layer resulting from performing steps d) to f).

3. A method according to claim 1 , wherein, during step f), the surface of the top of the base of the wiper is followed in a longitudinal direction prior to changing angular sector.

4. A method according to claim 1 , wherein, during step f), the laser source and the sources of powder material remain activated.

5. A method according to claim 1 , wherein, during step g), each layer results from the following sub-steps:

g1) forming two annular beads on the surface of the base of the wiper using the second powder material by moving the optical head and the nozzle during step f) angularly over the circumference relative to the previously-obtained localized region of extra thickness; and

g2) filling a zone situated between the two annular beads with the first powder material.

6. A method according to claim 1 , wherein, during step e), both the first source and the second source of powder material are activated simultaneously so that the nozzle projects a mixture of powder materials, the proportion between the first and second powder materials varying so as to build the tip of the wiper by gradually modifying the composition between the coating with a higher second material content, and the core.

7. A method according to claim 1 , wherein the optical head and the spray nozzle are secured to each other in a common projection assembly of position that can be adjusted relative to the support.