Method for manufacturing a blade comprising a bathtub tip integrating a small wall

Abstract

The invention relates to a method for manufacturing a turbine engine blade (16) including an active-surface wall (17) and a passive-surface wall (18) separated from one another, this blade (16) including a tip that has a closing wall grouping together the active-surface (17) and passive-surface (18) walls in the region of this tip to define the bottom (23) of a bathtub tip shape located at the tip of the blade, the method comprising a moulding step implementing a core defining the bathtub tip shape. According to the invention, there is a step of adding metal to the bottom (23) of the bathtub tip by means of a Direct Laser Additive Manufacturing (CLAD) method, to deposit material onto the bottom of the bathtub tip to form therein an inner partition (28) supported by the bottom thereof (23).

Claims

1. A method for manufacturing a turbine engine blade, the turbine engine blade extending along a spanwise direction and including a bathtub tip portion having an active-surface wall, a passive-surface wall spaced from the active-surface wall, and a closing wall grouping together the active-surface wall and passive-surface wall, the active- and passive-surface walls each extending beyond the closing wall to respective top edges, the bathtub tip portion having a bathtub tip shape, the method comprising: a moulding step implementing a removable core, the removeable core defining after removal a full extent of the bathtub tip portion, including the respective top edges of the active- and passive-surface walls, after moulding of the bathtub tip portion, a step of adding metal to the closing wall at the bottom of the bathtub tip portion with an additive manufacturing method adding metal, by depositing metal powder on the closing wall, to form an inner partition supported by the closing wall, the inner partition having an extremity joining the top edge of the active-surface wall and another extremity joining the top edge of the passive-surface wall, and a machining step, for machining the deposited metal powder to carryout shape finishing of the inner partition, the machining step occurring after the step of adding metal.

2. The method according to claim 1, wherein the metal powder is deposited so as to extend from the top edge of the active-surface wall to the top edge of the passive-surface wall.

3. The turbine engine blade obtained with the method according to claim 1.

4. A turbine engine comprising the turbine engine blade according to claim 3.

5. The method according to claim 1, wherein the machining step is carried out by electroeroding.

6. The method according to claim 1, wherein the active-surface wall and the passive-surface wall surround the closing wall.

7. The method according to claim 1, wherein the removeable core implemented is a moulded core.

8. A method for manufacturing a turbine engine blade, the turbine engine blade including a bathtub tip portion having an active-surface wall, a passive-surface wall spaced from the active-surface wall, and a closing wall grouping together the active-surface wall and passive-surface wall, the active-surface wall and the passive-surface wall each extending continuously beyond the closing wall to respective top edges, the bathtub tip portion having a bathtub tip shape, the method comprising: a moulding step implementing a removable core, the removeable core defining after removal a full extent of the bathtub tip portion, including the respective top edges of the active- and passive-surface walls, a step of adding metal to the closing wall at the bottom of the bathtub tip portion with an additive manufacturing method adding metal, by depositing metal powder on the closing wall to form an inner partition supported by the closing wall, the inner partition having an extremity joining the top edge of the active-surface wall and another extremity joining the top edge of the passive-surface wall, and a machining step, for machining the deposited metal powder to carryout shape finishing of the inner partition, the machining step occurring after the step of adding metal.

9. The method according to claim 8, wherein the metal powder is deposited so as to extend from the top edge of the active-surface wall to the top edge of the passive-surface wall.

10. The method according to claim 8, wherein the removeable core implemented is a moulded core.

11. The turbine engine blade obtained with the method according to claim 8.

12. A turbine engine comprising the turbine engine blade according to claim 11.

13. A method for manufacturing a turbine engine blade, the turbine engine blade having a bathtub tip portion that includes an active-surface wall, a passive-surface wall, and a closing wall grouping together the active-surface wall and passive-surface wall, the active- and passive-surface walls each extending beyond the closing wall to respective top edges of the active- and the passive-surface walls, the bathtub tip portion having a bathtub tip shape, the method comprising: a moulding step that forms the closing wall by moulding; an additive manufacturing step of adding metal to the closing wall by depositing metal powder on the closing wall to form an inner partition supported by the closing wall; and a machining step, for machining the deposited metal powder to carryout shape finishing of the inner partition, the machining step occurring after the step of adding metal.

14. The method according to claim 13, wherein the moulding step forms a full extent of the bathtub tip portion by moulding, including the active- and passive-surface walls.

15. The method according to claim 14, wherein the active-surface wall and the passive-surface wall surround the closing wall.

16. The method according to claim 13, wherein the inner partition has an extremity joining the top edge of the active-surface wall and another extremity joining the top edge of the passive-surface wall.

17. The turbine engine blade obtained with the method according to claim 13.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 already defined is an overview of a double flow turboreactor represented in a side cross-section;

(2) FIG. 2 already defined is an overview of a reactor blade;

(3) FIG. 3 is a partial perspective view of a blade bathtub tip that comes from casting;

(4) FIG. 4 is a schematic representation of the method used in the invention to add material on the bottom of the blade bathtub tip;

(5) FIG. 5 is a partial perspective view of a bathtub tip in the bottom of which a material has been deposited, conforming with the invention, in view of a machining operation to put the deposited material in the shape of a partition;

(6) FIG. 6 is a partial perspective view of a blade bathtub tip according to the invention, comprising a partition obtained by depositing material then by machining.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(7) As can be seen in FIG. 3, a blade 16 such as coming from casting, comprises an active-surface wall 17 and a passive-surface wall 18 which substantially extend along the spanwise direction EV of this blade, and of which the top edges, referenced by 19 and 21, define the tip of this blade 16.

(8) These active-surface and passive-surface walls 17 and 18 are separated from one another, while being connected to one another, on the one hand, at the level of the leading edge of the blade, referenced by 22, and on the other hand, at the level of the trailing edge of the blade which does not appear in the figure, these two edges extending almost parallel to the spanwise direction EV.

(9) These walls are again connected to one another at the blade tip by a wall known as a closing wall, referenced by 23, and which extends perpendicularly to the spanwise direction, while being remote along the spanwise direction by a certain height in relation to the tips of the edges 19 and 21. The edges 19 and 21 thus go beyond the closing wall that they surround, to define with it, the bathtub tip 24 of the blade tip, of which they constitute the edges, and of which the closing wall constitutes the bottom.

(10) The basis of the invention is to use a method known as an Additive Manufacturing method, to add metal to the bottom of the bathtub tip of the blade, such as coming from casting, so as to form an inner partition in this bathtub tip. The method used is a method that fuses metal powders by a laser beam, depositing in successive layers. Other metal deposit methods can be considered.

(11) Such a method, which is usually referred to by the trademark CLAD, namely the Direct Laser Additive Manufacturing method, consists of using equipment 26 to generate a laser beam 27 to fuse on a substrate, which is here the bottom 23 of the bathtub tip 24, one or several metal powders 29 added by a nozzle 31, so as to successively constitute deposit layers 32 of a metal material. This nozzle is a coaxial nozzle, able to carry out the homogenous injection of metal powders through a laser beam.

(12) With this method, powders fused by the laser constitute a homogenous and dense deposit on the surface or layer which supports them, which is itself also fused during the process. As there is no contact, in particular, between the nozzle and the substrate, the method is exempt from wear and tear. Successive deposits or stacks are protected all throughout the method, by an inactive gas to counter oxidation problems.

(13) This method enables deposits to be made, by targeting with a certain precision, the places where the material is added. It is also possible to use two metals from different additions to produce, if necessary, an alloy of evolving proportions according to the height. This enables to optimise different aspects, like mass, adhesion with the substrate, in other words, dilution and porosity, as well as abradability, abrasivity, dilatation or other properties.

(14) Generally, the material deposited is that chosen according to the substrate to have a suitable mechanical stability, abradability, as well as compatibility with the substrate, which are suitable, in particular, concerning dilution and porosity.

(15) As can be seen in FIG. 3, the blade bathtub tip, raw from casting, comprises a bottom 23 which is flat, and according to the invention, an inner partition is formed on this flat bottom, by adding material according to the CLAD method, then by machining the material thus added, to give it a surface condition and a rating corresponding to predefined criteria

(16) As can be seen in FIG. 5, the material added by the CLAD method is deposited according to the trajectory and the shape of the partition to produce, so as to constitute an addition of material 25 that has a general shape corresponding to that of the partition to obtain. As represented in FIG. 5, the material added constitutes a deposit which could be relatively rough in view of the tolerances to obtain concerning the geometric definition of the finished partition. These size tolerances are stipulated by aerodynamic limitations to which the blade bathtub tip must meet when functioning. The metal deposit, referenced by 25 in FIG. 5, thus constitutes the raw material from which the partition will be formed.

(17) This deposit is then machined to constitute the actual final partition which appears in FIG. 6, wherein it is referenced by 28. This machining can be carried out by electroerosion, according to the method known by the acronym EDM, meaning Electrical Discharge Machining. This machining can also be ensured by means of drill or similar-type cutting tools, which enables shape finishing to be carried out, enabling to constitute the partition 28 as such.

(18) The invention has been defined with an Additive Manufacturing method by fusing powders by laser beam, depositing successive layers, but other methods can be used. In particular, the SWET method, meaning Superallow Welding at Elevated Temperature, can also be considered.

(19) Generally, the method according to the invention thus enables to manufacture a blade comprising, at the level of the bathtub tip thereof, a small wall which could have any type of shape, without adding any additional limitation to the moulding process that occurs in manufacturing this blade.