EP1537950A1 - Protection mask for the surface treatment of blades for turbine engines - Google Patents

Abstract

Mask protecting turbine blade surfaces during treatment by sand blasting and plasma-metallization. The surfaces to be protected are surfaces either on transverse fins (15, 17) of the turbine blade (10) or surfaces (18) at its root. The mask comprises a section (100) following the appropriate contours and including apertures opening over surfaces to be treated.

Description

The invention relates to the protection of turbomachine blade surfaces prior to a partial surface with a character abrasive or simply to surfaces not to be treated. She also relates to the application of a surface protection for any part mechanics to be subjected to a similar surface treatment,

With reference to FIG. 1, a turbine engine blade 10, here compressor or welding turbojet, is a pay 11 having an intrados face and an extrados face 19, a stilt 12 and a foot 13 slotting into an axial cavity formed in the axis of the central disc of the support (not shown). A platform 14 separates the blade 11 from the stilt 12.

The central disk thus carries a certain number of vanes whose blades are all kept equidistant from each other, in particular by fins 15 located on a median portion of each face of the blades and of which, for two adjacent fins of two neighboring blades, the ends are in contact.

The surface treatment of blade 10, generally made of titanium or titanium alloy, comprises a first treatment E1 of the surface by sandblasting to increase the roughness, in preparation for a second said metallization step E2 with thermal spray deposition. It is the case in particular of the projection by means of a plasma torch, either of a copper alloy, for example Cu - Ni - In (copper - nickel - indium), whose ductility makes it possible to dampen the vibrations of the motor by operation at the blade contacts with the central disk, either of tungsten carbide, for example WC-Co (tungsten carbide-cobalt) whose hardness makes it possible to avoid the wear caused by the friction between adjacent fins.

The plasma torch projects the alloy coating at high speed and (more than 2500 ° K.) on the surface to be treated for get his hang.

Steps E1 are very abrasive and steps E2 are undesirable in outside the surfaces to be treated. They require in the case of the treatment fins, to interpose a protection between the tools of sandblasting and / or the plasma torches and the faces 19 of the blades 10 so as to subtract these from their effects. More specifically, only surfaces 17 of the ends of fins 15 to be put into contact with those 17 of the other fins of the neighboring blades, are submitted, during manufacture, to the surface treatments above. In in addition to the two faces 19 of the blade 11 have helical surfaces, very precise geometry, which must be protected.

In the case of foot treatment, the only contact surfaces 18, located on both sides of the foot of the blade 10 are to be coated. The other areas 12 and 13 of the foot must be protected at least during E2 treatment.

Currently, for this, the operator manually applies ribbons Adhesives with sufficient mechanical and thermal resistance around surfaces to be treated.

These manual operations are long and tedious because of the complexity of the blade shapes, the precision required and the lack of accessibility of the surfaces to be protected. They do not provide a quality constant level since they are not perfectly repetitive and poor adhesion of adhesive tapes presents a risk of masking or even detachment of the deposited coating. In addition when the metallization, it is found that particles reach the layer in formation after bouncing off the protective surface. The quality of the snagging or homogeneity of these particles is then not sufficient, and the corresponding areas are less resistant to stresses applied on turbomachines.

There is therefore a need to improve the productivity and quality of these operations.

In addition, the operators of these operations are subject to particularly due to the sustained attention required for their execution; they are also at risk of musculoskeletal disorders (TMS) consecutive to the realization of repetitive actions.

To remedy all these drawbacks, the applicant proposes a protective mask for the surface treatment of surfaces of a turbomachine blade having a foot and possibly fins, disposed around said surfaces while resisting the effects of surface treatment, while constituting a dismountable tool and reusable, characterized in that said surfaces being located either on the foot of the dawn is at the end of the fin, it is composed of minus a piece matching the shape of the foot or fins respectively, and having lights revealing said surfaces to be treated,

The surface treatment comprises a sandblasting step and / or a step of metallization.

"Tooling" means a part or a set of parts at least partly rigid whose shape and materials are suitable for masking parts of surfaces to be protected. Tooling materials are also able to withstand the operational environment of operations E1 and E2. Thanks to the tooling of the invention, all operations are eliminated. manual application of adhesive tape, and the masking is perfectly repetitive.

Preferably, the step E2 causing a rise in temperature, the protective mask is provided to withstand the thermal effects of surface treatment, here a plasma deposit.

More preferably, step E2 requiring mechanical treatment beforehand, the protective mask of step E1 is of a material resistant to the abrasive action of sanding.

Advantageously, the protective mask is made of stainless steel or silicone material or polymer material.

Optionally, the mask can be used both for sanding and for plasma deposit, and can be reused for a series of turbomachinery.

• la figure 1 représente une vue perspective d'une aube de compresseur;
• la figure 2 représente une vue de cote d'une première application de l'invention consistant en un conformé pour permettre le traitement du pied d'une aube,
• la figure 3 représente un montage permettant le traitement simultané de plusieurs aubes,
• les figures 4A et 4B représentent des vues perspectives d'une autre application de l'invention, consistant en des masques pour la protection des surfaces d'une aube contre le sablage et le dépôt plasma sur les surfaces à traiter de son pied; et
• la figure 5 représente une vue perspective d'une seconde application de l'invention, consistant en un masque pour la protection des surfaces d'une aube contre le sablage et le dépôt plasma sur les surfaces à traiter de ses nageoires ;

The invention will be better understood with the aid of the following description of a protective mask for two applications of the invention and the appended drawing in which:

• Figure 1 shows a perspective view of a compressor blade;
• FIG. 2 represents a side view of a first application of the invention consisting of a shape for allowing the treatment of the root of a blade,
• FIG. 3 represents a mounting allowing the simultaneous treatment of several blades,
• FIGS. 4A and 4B show perspective views of another application of the invention, consisting of masks for protecting the surfaces of a blade against sanding and plasma deposition on the surfaces to be treated of its foot; and
• FIG. 5 represents a perspective view of a second application of the invention, consisting of a mask for protecting the surfaces of a blade against sanding and plasma deposition on the surfaces to be treated with its fins;

Figure 2 shows the lower part of a compressor blade of which we see the blade 11, the platform 14 and the foot 13. It is here in shape dovetail and rectilinear (non-exhaustive case, quoted example). In order to ensure a damping of the vibrations of the dawn in its cell during the operation of the engine, apply a 13R coating located in areas that are in contact with flanks of the cell. To apply this coating by torch according to the invention, a mask 100 which espouses the shape of the dawn stake in part, and can be set up by simple embedding. The mask 100, advantageously made of stainless steel, has a determined thickness. A 100R window is provided in this mask, on each side of the foot. The shape and dimensions of windows depend on those of the 13R coating that is to be applied by the plasma torch. This 13R coating is located on both pile surfaces. who will be in contact with the disk on the turbine engine.

Since the plasma torch T is preferentially placed perpendicular to the surface to be treated, the walls of the window are also perpendicular to this surface. The window allows the passage of molten metal particles during the metallization operation with the plasma torch. This arrangement has the advantage that the particles molten metal from the plasma torch that are not directed the axis of the window are deposited on the mask in the bordering area window 100R without being reflected inward. These particles do not so do not disturb the formation layer by rebound. After of a layer of desired thickness, the mask is removed. The 13R coating has exactly the shape defined by that of the window it It is not necessary to carry out a retouching operation.

The mask is put back into service for the treatment of other blades if the Metallic area at the edge of the window is not too thick. The mask can be so used several times before requiring a fitness by "demetallization" of the area bordering the window. A such operation of restoring the mask is advantageously carried out by chemical techniques known to man of the job.

If a preliminary operation of surface preparation is necessary, uses the same mask to protect surfaces that should not receive sanding.

Such a mask also has the advantage of allowing the treatment of several blades at the same time. For this purpose a groove 110 is provided in the bottom wall of the mask to allow then to apply a alignment bar 43.

FIG. 3 shows a mounting for the treatment of some dawns. We assemble the blades equipped with their mask protection 100 on a single tool 40.

The tool 40 comprises a frame 42 on which the blades have been fixed, blade in down, so as to present the masks on the top. 100R windows are visible. A bar 43 connects the masks 100 by the grooves 110. Thanks to this bar you can precisely align the masks one by one compared to others. Flanges 41 are placed along the row of masks so as to cover and protect the platforms of the blades. Once the editing is done, we place the treatment tool in the direction from the first window and move it at a fixed speed in parallel at the windows. By this arrangement sandblasting treatment is allowed followed by metallization or metallization of a set N of blades ensuring a constant quality.

FIGS. 4A and 4B show a masking device adapted to blades with a curvilinear foot, such as blades of blower size.

For a step E1. sandblasting surfaces 18 of the foot 13 of the blade 11 of a blade 10, there is provided, with reference to FIG. 4A, a mask 100 ' protection device comprising, fixed on a base 132, a frame 125 of material silicone or polymer material arranged to be able to be mounted in fitting the foot 13 of the blade 11 while allowing to appear, through lights 124 surfaces 18 to be treated.

For this, the frame comprises two half-shells 121 matching the shapes of the above surface, made according to the same plans that made it possible the realization.

These two half-shells 121 are assembled by locks 123 removable, for example fitting themselves in the two half-shells 121, and can therefore be dismantled to remain fit for a new editing and remain available for the treatment of another dawn.

For a step E2 plasma deposition of the surfaces 18 of the foot 13 of the blade 11, there is provided, with reference to FIG. 4B, a mask 100 "'of protection comprising, fixed on a base 132 ", four supports 127 arranged to support two spacers 126, all made of stainless steel, now payroll 11 and two masks 128, stainless steel, now and covering the foot 13 of the blade 11, on either side of the foot, while revealing, through lights 131 surfaces 18 to be treated.

here, to exactly regulate the extent of the surface to be treated, the periphery lights 131 is lined with tabs 129 limiting this extent to will. The position of the tabs 129 is adjustable by sliding on the masks 128 and is held there by clamping screws 130.

In the example of the figure the tabs 129 limit only the length lights 131 but the same device is possible also in width, both devices can easily be simultaneously.

FIG. 5 shows an embodiment of the invention corresponding to the treatment of the fins of the dawn. A mask 239 of protection comprising two half-shells 233, matches the shape of the fins according to a chimney 234 and faces 19 adjacent thereto. These forms are directly deduced from the plane of dawn 10. The two half-shells 233 are assembled together on the surface to be protected by the means of four clips 236, for example stainless spring blades embedding in holes (not visible in the figure) provided for this purpose in the mask 239.

The mask in this case is made of silicone material, this material is both resistant to sanding mechanics and heat treatment of metallization.

The two half-shells 233 reveal the surfaces of the ends of fins 17 to be treated through lights 235 so that these ends remain sufficiently clear of the mask of some height "e".

The mask 239 is used both for sandblasting and for plasma deposition. is still reused a number of times,

The present invention is not limited to the embodiments represented. It encompasses all variants available to humans of career.

Claims (8)

Protective mask for the surface treatment of surfaces (17, 18) of a turbomachine blade (10) comprising a foot and possibly fins, disposed around said surfaces while resisting the effects of the surface treatment, while constituting a tooling removable and reusable, characterized in that said surfaces being located either on the root of the blade or at the end of the fin, it is composed of at least one piece (100, 100 ', 100 ", 239) conforming to the shape foot or fins respectively, and having lights revealing said surfacs to be treated. Mask according to claim 1, comprising at least two half-shells (121, 233) held together by bolts or clamps (123.236). Mask according to one of claims 1 and 2, consisting of a material resistant to the thermal effects of a plasma deposit. Mask according to one of claims 1 to 3, constitutes a material resistant to the thermal effects of sanding. Mask according to one of claims 1, 3 and 4, conforming to the shape of the foot of dawn and made of stainless steel. Mask according to claim 5, which can be in place simply entrenchment. Mask according to one of claims 1 to 4, made of material silicone or polymer. Mask according to claim 7 wherein the blades of turbomachines comprise fins (15) whose ends are treat, Jesuit ends remain clear of the mask of some height "e".

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