Method for repairing an upstream rail of a turbine engine turbine casing

Abstract

An upstream rail of a turbine engine turbine casing, which includes a casing body extending along a longitudinal axis, includes a base including a radial face, extending substantially radially from the casing body, a plate including an upper face, extending substantially along the longitudinal axis, a connection portion between the base and the plate, including a concave face connecting the radial and upper faces, the concave and radial faces extending on either side of an edge. The upstream rail is repaired through a method including covering a surface with a solder, the surface including the upper and concave faces such that the solder extends until the edge, and machining the covered surface, in a single action, in a direction toward the radial face, so as to reshape the surface, wherein the machining of the covered surface is performed on a portion of the radial face.

Claims

1. A repaired upstream rail of a turbine engine turbine casing, said casing including a casing body extending along a longitudinal axis, said upstream rail comprising: a base including a radial face, extending substantially radially from the casing body, a plate including an upper face, extending substantially along the longitudinal axis, a connection portion between the base and the plate, including a concave face connecting the radial face and the upper face, the concave face and the radial face extending on either side of an edge, said repaired upstream rail including: a covered surface with a solder, said covered surface including the upper face and the concave face, such that said solder extends until the edge, and the covered surface has been reshaped by machining on a portion of the radial face to form a repaired concave face.

2. The upstream rail according to claim 1, wherein a depth of the machining of the radial face is at most 0.1 mm.

3. The upstream rail according to claim 1, wherein the solder is applied by Tungsten Inert Gas welding.

4. The upstream rail according to claim 1, wherein the covered surface includes a downstream side face and a lower face of the plate.

5. The upstream rail according to claim 1, wherein the covered surface has no machining springback in the concave face.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Figures are presented purely by way of indicating and in no way limiting example of the invention. Figures show:

(2) in FIG. 1, already described, a schematic representation of a casing including rails to support a nozzle guide

(3) in FIG. 2, a schematic representation of an upstream rail of the casing of FIG. 1, in a cross-section view

(4) in FIG. 3, a schematic representation of the steps of an embodiment of the method according to the first aspect of the invention

(5) in FIG. 4, a schematic representation of the upstream rail of FIG. 2, depicting a covering step of the method

(6) in FIG. 5, a schematic representation of the upstream rail of FIG. 3, depicting a machining step of the method.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

(7) FIG. 2 shows a turbine engine casing 19, said turbine engine generally extending along a longitudinal axis. More precisely, FIG. 2 is a partial view of the casing in a longitudinal cross-section view. Said casing 19 includes a generally cylindrical casing body 21, and a plurality of rails among which an annular upstream rail 20.

(8) In a longitudinal cross-section, the upstream rail 20 has the general shape of an L, and thus includes several parts: a base 22 integral with the casing body 21, extending substantially radially from the casing body 21 in the direction of the longitudinal axis a plate 23 extending substantially longitudinally from upstream to downstream a connection portion 24 connecting the base 22 and the plate 23.

(9) By “substantially radially” or “substantially longitudinally”, it is meant a radial or longitudinal extension with more or less 5°.

(10) The plate 23 especially includes an upstream side face 30 and a downstream side face 31 extending generally radially, and a lower face 32 extending longitudinally between the upstream side face 30 and the downstream side face 31. The plate 25 further includes an upper face 25, extending longitudinally between the connection portion 24 and the downstream side face 31. A nozzle guide upstream hook is intended to rest upon said upper face 25.

(11) The upper face 25 of the plate 23 adjoins a concave face 26 of the connection portion 24, against which an end of the upstream hook is intended to bear.

(12) The concave face 26 adjoins a radial face 27 of the base 22, having itself formed thereon a rounded face 28 of the base 22, said rounded face 28 being directly connected to the casing body 21. It is noted that the concave face 26 and the radial face 27 are located on either side of an edge 29.

(13) Under the effect of the contact with the nozzle guide, the upper face 25 of the plate and the concave face 26 are likely to be damaged. Yet, the connection portion 24 being submitted to strong stresses, a machining springback is to be avoided on the concave face 26 of the connection portion 24.

(14) FIG. 3 schematically depicts the steps of a method 40 for repairing the upstream rail 20. The method 40 includes: a step of covering 41 a surface with a solder 33, said surface including the lower face 32, the downstream side face 31 and the upper face 25 of the plate, and the concave face 26 of the connection portion 24. Covering is performed so that the solder 33 extends substantially until the edge 29.

(15) FIG. 4 shows the upstream rail 20 of the third turbine stage, at the end of the covering step. It is noted that, according to a preferred embodiment, covering is performed by Tungsten Inert Gas (TIG) welding, well known to those skilled in the art. Furthermore, the solder 33 is ideally of the same material as the upstream rail, in order to avoid material discontinuities in the repaired upstream rail. A step of machining 42 the covered surface, from the lower face 32 of the plate 23 and in the direction of the radial face 27, such that machining ends in the radial face 27. Indeed, a machining springback in the radial face 27 is not likely to embrittle the upstream rail 20, the area close to the vertical line 27 being the least strained area of the upstream rail 20. Machining is performed in a single action in order to avoid intermediate machining springbacks, and possibly in several passes. At the end of machining, the surface is reshaped, suppressing wear traces on the upper face 25 of the plate 23 and on the concave face 26 of the connection portion 24. FIG. 5 shows, with the thick line 34, the machining profile. It is noted that the radial face 27 includes a machining springback 35. A step of machining 43 the radial face 27 to suppress residues of solder 33 which could have disseminated on the radial face 27. Machining is light, with a maximum depth of 0.1 millimetre.

(16) This method enables an exit of the machining tool in the least strained area of the upstream rail (that is at the radial face) and remote from the wear area which initiated the repair.

(17) It is noted that this method is adapted to repair upstream rails of all the turbine stages, although these rails have slightly different profiles. Indeed, whatever the upstream rails to be repaired, they all have a base including a radial face, a plate comprising an upper face, and a connection portion including a concave face.