FR3043686A1 - METHOD FOR APPLYING A FLEXIBLE FILM TO A COMPLEX SHAPE PART - Google Patents

Abstract

The invention relates to bonding a protective film (16) to a three-dimensional piece (10) comprising at least one radius of curvature. This method comprises the positioning of the protective film (16) and a layer of adhesive (18) on a cavity (12), the protective film (16) having at least one positioning tab of the protective film (16) and the adhesive layer (18) on this surface, heating the protective film (16) and the adhesive layer (18) at a first activation temperature of the adhesive layer (18), pressing the protective film (16) and adhesive layer (18) against each other on the impression (12), cooling of the protective film (16) at ambient temperature and cutting of the positioning tab .

Description

BACKGROUND OF THE INVENTION [0001] The present disclosure relates to the protection against erosion, shock or ultraviolet radiation of fiber-reinforced organic matrix composite material parts, such as, for example, fan blades. turbojet engine or acoustic panels.

In this context, the term "blades" refers to both the stationary or mobile fan blades and the overhead propeller blades.

In order to limit their weight, these blades are typically organic matrix composite, for example polymer, reinforced with fibers. Although these materials have generally very good mechanical properties, especially with respect to their mass, they have a certain sensitivity to erosion which may be due in particular to friction with sand and / or other abrasive elements and / or in the rain.

[0004] The blades generally comprise a leading edge shield which protects the leading edge of the blade against impacts and erosion. However, the dawn body is not protected by the shield. This shield is usually made of metal material, it is not planned to cover the entire dawn with the shield.

Also, to protect the erosion of the blade body not protected by the leading edge shield, the blade is covered with an anti-erosion coating which is generally in the form of a soft protective film that is glued on the dawn by means of a layer of glue.

The application of the adhesive layer and the anti-erosion coating may be tricky. Indeed, the size of the dawn is such that this operation can not be performed by a single operator.

In addition, the blade must be preheated to reduce the risk that the protective film does not move once in place and to enable the activation of the adhesive layer. Indeed, the adhesive force or tack of the adhesive layer and thus the bonding of the protective film increases with the temperature of the adhesive layer. It also refers to glue low tack at room temperature, the tack is defined as the adhesive power of a glue, the ability of an adhesive to hold together two supports.

It is understood that the positioning of the protective film and the adhesive layer on the blade is an operation that must be performed relatively quickly to prevent the cooling of the blade at a temperature at which the adhesive layer is less easily activated. However, rapid positioning of the protective film may increase the presence of folds and / or air bubbles between the anti-erosion coating, the adhesive layer and / or the blade. During the step of positioning the protective film, the latter can also be stretched too far on the surface of the blade and it can be torn. The protective film may also be poorly positioned.

In addition, the shape of the blade being relatively complex, the risk of formation of folds and / or air bubbles between the anti-erosion coating, the adhesive layer and / or the blade increases.

The presence of folds and / or air bubbles is at the expense of the quality of the bonding of the protective film on the blade, and thus the protection of the blade by the protective film. Moreover, these defects can also induce a loss of aerodynamics.

OBJECT AND SUMMARY OF THE INVENTION [0011] The present invention aims to remedy at least in part these disadvantages.

For this purpose, the subject of the invention is a process for bonding a protective film to a three-dimensional part comprising at least one radius of curvature, characterized in that the method comprises the following steps: positioning of the film and a layer of adhesive on a footprint at least partially reproducing a surface of the three-dimensional part or a surface complementary to the three-dimensional part, the protective film comprising at least one positioning tab of the protective film and the layer glue on this surface; heating the protective film and the adhesive layer at a first activation temperature of the adhesive layer; - Pressing the protective film and the adhesive layer against each other on the imprint to form the protective film on the imprint; - cooling of the protective film at room temperature; - Cutting of the positioning tab.

For example, the three-dimensional part may be a turbojet fan blade, a turbojet casing, a fixed stator blade, an acoustic panel or an inter-blade platform.

The three-dimensional piece may be a three-dimensional piece with double curvature.

The term "three-dimensional double curvature piece" means a three-dimensional piece whose surface is not flat and whose surface is defined by a plurality of radii of curvature, that is to say by at least two radii of curvature. different. We will also say that this three-dimensional piece is of complex shape.

These parts are large in size and have complex surfaces defined by a plurality of radii of curvatures.

The protective film is generally a film whose thickness is small compared to its length and width. In addition, the protective film is a film that can be flexible.

The protective film comprising at least one positioning tab, preferably several positioning tabs, the protective film can be easily handled and positioned on the complex surface of the impression reliably. The positioning tabs are sacrificial portions of the positioning film, that is to say they will be arranged on areas of the three-dimensional part that will not be covered by the protective film once the three-dimensional part is manufactured and ready. to be mounted in a larger set and / or to be used. The positioning tabs are thus cut after gluing the protective film on the three-dimensional part. Also, the positioning of the film over the entire surface to be protected is relatively simple because it is not necessary to ensure a faultless positioning of the positioning tabs on the three-dimensional part or precise positioning of the edges of the positioning tabs on the three-dimensional piece. The protective film is thus manipulated and positioned by means of sacrificial portions of the protective film.

In addition, the imprint can be heated after positioning the protective film on the footprint, so that the positioning of the protective film is facilitated because at room temperature the adhesive layer adheres little to the footprint. Indeed, the adhesive force or tack of the adhesive layer and thus the bonding of the protective film increases with the temperature of the adhesive layer. We also speak of glue with low tack at room temperature.

The pressing ensures an effective contact between the protective film, the adhesive layer and the imprint and allows at least to secure the protective film and the adhesive layer.

After cooling to room temperature, the protective film is deformed and retains the deformations that have been imposed by the imprint.

The adhesive layer may comprise a thermosetting glue.

This type of glue ensures a bond between the two elements it assembles.

The first activation temperature may be lower than a polymerization temperature of the adhesive layer, the heating may be achieved by the imprint and the adhesive layer may bear, on a surface opposite to a surface in contact with the protective film, a non-adhesive release film. For example, the first activation temperature may be between 40 ° C and 80 ° C.

By heating the protective film and the adhesive layer by the imprint, it increases the tack of the adhesive film so that the protective film and the adhesive layer are secured to one another. However, since the second temperature is lower than the polymerization temperature of the adhesive layer, the polymerization of the adhesive layer does not begin. Also, although the adhesive layer is heated, the polymerization capacity of the adhesive layer is not degraded because the heating temperature is lower than the polymerization temperature of the adhesive layer.

Furthermore, the heating being achieved by the imprint, the entire contact surface between the imprint and the assembly formed by the protective film, the adhesive layer and the non-adhesive detachable film can be easily heated from relatively uniform way.

In addition, thanks to the non-adhesive release film, the assembly formed by the protective film, the adhesive layer and the non-adhesive release film can be easily removed from the impression.

The imprint can directly reproduce at least partially the surface of the three-dimensional part, the non-adhesive detachable film being in contact with the imprint.

The heating is then on the side of the non-adhesive detachable film.

The footprint may at least partially reproduce a surface complementary to the surface of the three-dimensional part, the protective film being in contact with the impression.

The heating is then on the side of the protective film.

The imprint, on which the non-adhesive detachable film, the adhesive layer and the protective film are positioned, may be arranged in an enclosure comprising a flexible membrane, and the protective film and the adhesive layer may be pressed against each other on the impression by the flexible membrane.

The flexible membrane may take the form of the imprint and the pressure can be applied relatively uniformly over the entire protective film.

The chamber can be evacuated and the flexible membrane is then pressed by the vacuum to the footprint so that the protective film, the adhesive layer and the non-adhesive detachable film are also pressed against the imprint . The evacuation can be achieved through through holes present in the enclosure, on a wall of the enclosure or on the cavity itself. The vacuum is for example a primary vacuum.

The chamber may be pressurized using a gas or a liquid under pressure on the side of the flexible membrane which is opposite the side intended to come into contact with the assembly formed by the protective film, the layer of glue and non-adhesive release film. The flexible membrane is then pressed by the pressurized gas or liquid onto the impression so that the protective film, the adhesive layer and the non-adhesive release film are also pressed against the impression.

The positioning of the protective film and the glue layer can be done by gluing the positioning tab on an inflatable bladder and the inflatable bladder is inflated to form the imprint.

The inflatable bladder may for example at least partially reproduce a surface complementary to the surface of the three-dimensional part when the inflatable bladder is inflated. The protective film, the adhesive layer and the non-adhesive release film are positioned on the inflatable bladder when it is not inflated. During inflation of the bladder, the protective film, the adhesive layer and the non-adhesive release film are heated to the first activation temperature of the adhesive layer, which allows the protective film, the adhesive layer and to the non-adhesive release film to gradually deform. When the inflatable bladder is fully inflated, the heating is stopped and the whole is cooled to room temperature. The inflatable bladder can also serve as a support for positioning the protective film, the glue layer and the non-adhesive release film on the three-dimensional part.

After cooling the protective film, we can store the protective film shaped.

It is thus possible to form protective films coated with a layer of glue and store them shaped. The presence of the positioning tab facilitates the handling of the protective films.

The protective film may be stored on a rigid shell at least partially reproducing the surface of the three-dimensional part.

The protective film being relatively flexible, one can use a rigid shell to store the protective film coated with the adhesive layer and the non-adhesive release film so that the protective film does not deform under its surface. own weight during storage. It is also possible to use the positioning tab so as to maintain the protective film plated on the rigid shell.

Several protective films can be arranged on the rigid shell.

Indeed, the protective film coated with the adhesive layer also bearing the non-adhesive detachable film, can be stacked several protective films on one another without the adhesive layer of a protective film stick to the protective film placed just below.

One can also pinch the protective film, the adhesive layer and the non-adhesive detachable film between two shells, at least one of the shells being rigid.

The method may also comprise the following steps: - removal of the non-adhesive detachable film; positioning the protective film shaped on the three-dimensional piece; heating the protective film and the adhesive layer at a second activation temperature of the adhesive layer, the second activation temperature being greater than or equal to the polymerization temperature of the adhesive layer; - Bonding the protective film on the three-dimensional piece by pressing the protective film and the adhesive layer on the three-dimensional piece.

The protective film being shaped on the imprint, it is then transferred to the three-dimensional to be glued.

The positioning of the protective film and the adhesive layer is facilitated by the fact that the protective film already has the shape of the three-dimensional part, its positioning on the three-dimensional part is simple. In addition, thanks to the positioning tab, the protective film can be easily manipulated.

The heating of the protective film and the adhesive layer allows an improved bonding of the protective film on the three-dimensional part. Indeed, the adhesive force or tack of the adhesive layer and thus the bonding of the protective film increases with the temperature of the adhesive layer. However, the heating temperature is such that the protective properties of the protective film are not deteriorated. Typically, at room temperature, the adhesive layer adheres little to the three-dimensional part. However, since the heating temperature is at least equal to the polymerization temperature of the adhesive layer, the adhesive is polymerized and bonding between the protective film and the three-dimensional part is performed. For example, the polymerization temperature of the adhesive layer is greater than or equal to 80 ° C, preferably greater than or equal to 90 ° C, even more preferably greater than or equal to 100 ° C and less than or equal to 180 ° C preferably less than or equal to 190 ° C, still more preferably less than or equal to 200 ° C.

The heating of the protective film and the adhesive layer can be achieved by preheating the three-dimensional part before positioning the protective film and the adhesive layer on the three-dimensional part. The preheating of the three-dimensional part may be carried out for example in an oven, by infrared lamps, by a heating mat or any other appropriate technique. Although the adhesive layer tends to stick to the three-dimensional part, thanks to the presence of positioning tabs, the positioning of the protective film on the three-dimensional part is easy.

The heating of the protective film can also be performed after the positioning of the protective film and the adhesive layer.

The three-dimensional piece may not be preheated, the positioning of the protective film is facilitated because at room temperature the adhesive layer adheres little to the three-dimensional piece.

The heating of the protective film can also be achieved by a combination of preheating the three-dimensional part before positioning the protective film and the adhesive layer and heating the protective film and the adhesive layer after positioning on the three-dimensional piece. The three-dimensional part may be preheated to a temperature below the polymerization temperature of the adhesive layer. Thus, the protective film can be positioned and held in place on the three-dimensional part by means of the adhesive layer which is at a temperature greater than ambient temperature but lower than the polymerization temperature of the adhesive layer. At the preheating temperature, the adhesion strength of the adhesive layer increases, thereby maintaining the protective film on the three-dimensional part.

The heating can also be performed after the pressing step.

The pressing makes it possible to ensure effective contact between the protective film, the adhesive layer and the three-dimensional part and to bond the three-dimensional film to the three-dimensional part. For example, the pressure exerted on the protective film may be less than or equal to 9 bar, preferably less than or equal to 5 bar and may be greater than 1 bar.

The adhesive layer may be coated on the protective film before the shaping step. The coating of the adhesive layer on the protective film can be performed at a third activation temperature of the adhesive layer, the third activation temperature being lower than the polymerization temperature of the adhesive layer. For example, the third polymerization temperature may be between 40 ° C and 80 ° C and the vacuum may be a primary vacuum.

The protective film and the adhesive layer being previously secured to one another, the pressure to be applied to the protective film and the adhesive layer during the shaping step can be reduced.

The third activation temperature may be equal to the first activation temperature.

The first activation temperature may be greater than or equal to a polymerization temperature of the adhesive layer and the impression may be the three-dimensional part. For example, the polymerization temperature of the adhesive layer is greater than or equal to 80 ° C, preferably greater than or equal to 90 ° C, even more preferably greater than or equal to 100 ° C and less than or equal to 180 ° C preferably less than or equal to 190 ° C, still more preferably less than or equal to 200 ° C.

The fingerprint is the three-dimensional piece, we will paste directly the protective film on the three-dimensional piece by means of the adhesive layer.

The heating of the protective film and the adhesive layer allows an improved bonding of the protective film on the three-dimensional part. Indeed, the adhesive force or tack of the adhesive layer and thus the bonding of the protective film increases with the temperature of the adhesive layer. However, the heating temperature is such that the protective properties of the protective film are not deteriorated. Typically, at room temperature, the adhesive layer adheres little to the three-dimensional part. However, since the heating temperature is at least equal to the polymerization temperature of the adhesive layer, the adhesive is polymerized and bonding between the protective film and the three-dimensional part is performed. For example, the polymerization temperature of the adhesive layer is greater than or equal to 80 ° C, preferably greater than or equal to 90 ° C, even more preferably greater than or equal to 100 ° C and less than or equal to 180 ° C preferably less than or equal to 190 ° C, still more preferably less than or equal to 200 ° C.

The heating step can begin after the pressing step.

We can easily have the protective film on the three-dimensional piece. Indeed, the positioning of the protective film is facilitated because at ambient temperature the adhesive layer adheres little to the three-dimensional part.

The shaping of the protective film is performed directly on the three-dimensional part which reduces the number of handling of the protective film.

The three-dimensional part, on which the adhesive layer and the protective film are positioned, can be arranged in a deformable bag and the pressing of the protective film and the adhesive layer on the three-dimensional piece is obtained by setting empty of the deformable pocket, for example a secondary vacuum.

The deformable pocket makes it possible to adapt to several different blade geometries. Indeed, the vacuum will press the pocket on the dawn regardless of the shape of the dawn. Furthermore, it is possible to glue the protective film over the entire surface to cover the three-dimensional part in one step. Indeed, it is possible to position the protective film and the adhesive layer over the entire surface of the three-dimensional part to be protected by means of the positioning tabs.

The three-dimensional part, on which are positioned the adhesive layer and the protective film, can be arranged in a mold, a first shell maintains the positioning of the protective film with the positioning tab and a second shell comprises a flexible membrane, and the protective film and the adhesive layer can be pressed against one another on the three-dimensional part by the flexible membrane.

The protective film is held in place by the first shell by at least one positioning tab. The pressure being applied to the protective film and the adhesive layer by a flexible membrane pressurized with a gas or a liquid, the pressure is applied relatively uniformly over the entire surface of the protective film. The second shell can also adapt to three-dimensional surfaces of the room that can vary slightly from room to room.

The three-dimensional part may comprise a composite organic matrix material, for example polymer, reinforced by fibers.

This type of material is generally a light material and having good mechanical properties, especially with respect to their mass. However, these materials are often more susceptible to erosion.

The three-dimensional part may comprise a metal alloy.

The protective film may be an abrasion-resistant film.

The protective film may comprise polyurethane.

This type of material provides effective protection against erosion of the three-dimensional part and can be deformed or shaped hot.

The protective film may comprise ethylene chlorotrifluoroethylene.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will emerge from the following description of embodiments of the invention, given by way of non-limiting examples, with reference to the appended figures, in which: Figure 1 is a perspective view of a turbojet fan blade; FIG. 2 is a perspective view of a protective film, a glue layer and a non-adhesive release film; - Figures 3 and 4 are perspective views illustrating a pressing step; FIGS. 5 to 7 are perspective views illustrating various means for shaping the protective film; - Figures 8 and 9 are sectional views of the storage of the protective film, the adhesive layer and the non-adhesive release film; FIG. 10 is a perspective view illustrating a heating step; - Figure 11 is a perspective view illustrating a pressing step; - Figure 12 is a perspective view illustrating a cutting step; - Figures 13 and 14 are perspective views of bonding means of the protective film; FIGS. 15 to 17 are perspective views of various three-dimensional pieces.

DETAILED DESCRIPTION OF THE INVENTION [0076] FIG. 1 represents a turbine engine fan blade 10. This blade 10 comprises a blade body 12 made of organic matrix composite material, for example polymer, reinforced with fibers and a leading edge shield 14 made of material having a better resistance to point impacts than the composite material of the body. dawn 12.

The leading edge shield 14 may be made of titanium-based alloy. The term titanium-based alloy, alloys whose mass content of titanium is the majority. It is understood that titanium is the element whose mass content in the alloy is the highest. The titanium-based alloy has, for example, a mass content of at least 50% titanium, preferably at least 70% titanium, more preferably at least 80% titanium.

The leading edge shield 14 may also be steel or metal alloy commonly referred to by the trademark Inconel ™. Inconel is later referred to as an alloy based on iron alloyed with nickel and chromium.

The blade body 12 is covered with a protective film 16 which is bonded to the blade body 12 by means of a glue layer 18, for example a thermosetting glue.

As can be seen in Figure 1, the blade body 12 is a three-dimensional piece comprising at least one radius of curvature, in particular, the blade body 12 is a three-dimensional piece with a double curvature, c ' that is, the blade body 12 is a complex surface that is defined by a plurality of radius of curvature.

The bonding process may comprise a preliminary step of coating the adhesive layer 18 on the protective film 16. This coating is carried out by pressing the protective film 16 on the adhesive layer 18 at a third temperature. activation of the adhesive layer 18, the third activation temperature being lower than the polymerization temperature of the adhesive layer 18, for example at 50 ° C.

FIG. 2 shows a stack comprising the protective film 16, the adhesive layer 18 and a non-adhesive release film 20, the adhesive layer 18 being disposed between the protective film 16 and the non-adhesive release film 20.

FIG. 3 shows a vacuum chamber 22 in which the protective film 16 and the adhesive layer 18 are disposed. The non-adhesive release film 20 allows the glue layer 18 to not adhere to the vacuum chamber 22. However, the adhesive layer 18 adheres to the non-adhesive release film 20. The vacuum is then formed in the vacuum chamber 20 so that the walls of the vacuum chamber 20 press the film of 16, the adhesive layer 18 and the non-adhesive release film 20 against each other, for example under a primary vacuum. The protective film 16 and the adhesive layer 18 are secured to one another by the application of this pressure and by heating the assembly to the third activation temperature of the adhesive layer 18 by a suitable means for example by placing the enclosure under vacuum in an oven or under an infrared lamp. Thanks to the non-adhesive release film 20, the assembly formed by the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 can be easily removed from the vacuum enclosure 22.

By increasing the temperature in the vacuum chamber 22, the tack of the adhesive film is increased, but the third temperature being lower than the polymerization temperature of the adhesive layer 18, the polymerization of the adhesive layer does not begin. not or remains limited. Also, although the adhesive layer 18 is heated, the polymerization capacity of the adhesive layer 18 is not degraded by the fact that the heating temperature is lower than the polymerization temperature of the adhesive layer 18.

FIG. 4 shows a pressure vessel 24 in which the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are disposed. The pressure vessel 24 also comprises a flexible membrane. 26. This flexible membrane 26 defines with the pressure vessel 24, a chamber 28 into which a gas or a liquid can be injected under pressure in order to press the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 against each other. The protective film 16 to the adhesive layer 18 are secured to each other by the application of this pressure and by heating the assembly to the third activation temperature of the adhesive layer 18. The film of 16, the adhesive layer 18 and the non-adhesive release film 20 may be heated by the pressurized gas or liquid or by any other suitable heating means. Due to the non-adhesive release film 20, the assembly formed by the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 can be easily removed from the pressure vessel 24.

This step of coating the adhesive layer 18 on the protective film 16 is performed before a shaping step of the protective film 16 on a cavity.

As shown in FIG. 5, the impression 32 may at least partially reproduce a surface of the blade body 12.

The method of bonding the protective film 16 to the blade body 12 comprises a step during which the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are positioned on the imprint 32, the non-adhesive detachable film 20 being in contact with the impression 32. The positioning of the protective film 16 and the adhesive layer 18 on the impression is made by means of a positioning tab 30 of the protective film 16 and the adhesive layer 18. As shown in FIG. 5, the positioning tab 30, represented by dotted lines, is intended to cover a portion of the leading edge shield 14. The positioning tab 30 is therefore a sacrificial portion of the protective film 16 which makes it easy to manipulate and position the protective film 16. Indeed, thanks to the positioning tab 30, it is no longer necessary to position the protective film 16 veryprecise.

All the handling steps of the protective film 16 are relatively easy because of the presence of the positioning tab 30.

The protective film 16 is for example a polyurethane film.

FIG. 5 represents a vacuum chamber for shaping the protective film 16 and the adhesive layer 18. The vacuum enclosure comprises a first frame 34 comprising a wall 36 on which the impression 32 rests. The protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are positioned on the impression 32, the non-adhesive release film 20 being in contact with the impression 32. The wall 36 comprises through orifices 38. The vacuum chamber also comprises a second frame 40 comprising a deformable membrane 42. The second frame 40 is placed on the first frame 34 and a vacuum is produced in the vacuum chamber by sucking the air present in the enclosure under The deformable membrane 42 is then deformed and pressed against the protective film 16 so that the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are pressed against the impression 32. . The assembly is then heated to the first activation temperature of the adhesive layer 18 by suitable means, for example by placing the enclosure under vacuum in an oven or under an infrared lamp. The first activation temperature here is less than the polymerization temperature of the adhesive layer 18. Due to the non-adhesive release film 20, the assembly formed by the protective film 16, the adhesive layer 18 and the non-releasable film adhesive 20 can be easily removed from the impression 32. Once returned to ambient temperature, the protective film 16 retains at least partly the shape given by the impression 32. The positioning of the protective film 16 and the protective layer 16 glue 18, once the non-adhesive release film 20 removed, on the blade 10 is simplified.

One can also consider shaping the protective film 16 and the adhesive layer 18 in a cavity 44, 48 reproducing a surface complementary to the surface of the blade 10. The method is similar to that described above.

In FIG. 6, the impression 44 at least partially reproduces a complementary surface of the surface of the blade 10.

The protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are arranged in the cavity 44 and held in place by the positioning tab 30. The protective film is in contact with the impression 44. Pressure is then applied to the non-adhesive release film 20 by means of an inflatable bladder 46 which is inflated by a gas or a liquid. The inflatable bladder 46 applies a relatively uniform pressure to the entire surface of the non-adhesive release film 20 so that the protective film 16, the glue layer 18 and the non-adhesive release film 20 are pressed against the impression 44.

The assembly is then heated to the first activation temperature of the adhesive layer which is lower than the polymerization temperature of the adhesive layer.

The protective film 16, the adhesive layer 18 and the non-adhesive release film 20 may be heated by the gas or the pressurized liquid in the inflatable bladder 46.

FIG. 7 represents another embodiment, in which, the impression 48 is formed by an inflatable heating bladder 48. The protective film 16, the glue layer 18 and the non-adhesive release film 20 are attached to the inflatable bladder 48 before inflation by means of the positioning tabs 30. The inflatable bladder 48 is then inflated and heated, for example by the gas or the liquid used to inflate the inflatable bladder. During inflation of the inflatable bladder, the protective film 16, the glue layer 18 and the non-adhesive release film 20 are heated to the first activation temperature of the glue layer 18 which is lower than the polymerization temperature of the adhesive layer 18. Thus, the protective film, the adhesive layer and the non-adhesive release film gradually deform. When the inflatable bladder 48 is completely inflated, it reproduces at least partially a surface complementary to the surface of the blade 10. The heating is stopped and the assembly is cooled to room temperature.

The inflatable bladder 48 can also serve as a support for positioning the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 on the blade 10.

Once shaped, the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 formed can be stored before being glued on the blade 10.

FIG. 8 represents the protective film 16, the adhesive layer 18 and the nonadhesive release film 20 disposed on a rigid shell 50 at least partially reproducing the surface of the blade 10 [0101] The protective film 16 being relatively flexible, it is possible to use the rigid shell 50 to store the protective film 16 coated with the adhesive layer 18 and the non-adhesive release film 20 so that the protective film 16 does not deform under its own weight during storage. One can also use the positioning tab 30 so as to maintain protective film 16 plated on the rigid shell50. The positioning tab 30 also facilitates the handling of the protective films 16.

Several protective films 16 may be placed on the rigid shell 50. Indeed, the protective film 16 coated with the adhesive layer 18 also carrying the non-adhesive release film 20, can be stacked several protective films 16 l one on the other without the adhesive layer 18 of a protective film 16 comes to stick to the protective film 16 disposed just below.

FIG. 9 represents the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 clamped between a first shell 50 and a second shell 52, at least the first or second shell 50, 52 being rigid. .

The method of bonding the protective film 16 to the blade body 12 comprises a step during which the non-adhesive release film 20 is removed.

The method also comprises a step during which the protective film 16 and the adhesive layer 18 are positioned on the blade body. The positioning of the protective film 16 and the adhesive layer 18 on the blade body 12 is achieved by means of the positioning tab 30 of the protective film 16 and the adhesive layer 18. As shown in FIG. 10 , the positioning tab 30 covers a portion of the leading edge shield 14. The positioning tab 30 is therefore a sacrificial portion of the protective film 16 which makes it easy to manipulate and position the protective film 16. In fact, thanks to the positioning tab 30, it is no longer necessary to position the protective film 16 very precisely.

Furthermore, the blade body 12 being at room temperature, the adhesive layer 18 adheres little to the blade body 12 which allows to easily reposition the protective film 16 when a defect such as a air bubble or crease is detected.

It is also possible to heat the protective film 16 and the adhesive layer 18 at a temperature lower than the first activation temperature of the adhesive layer 18, for example between 40 ° C. and 80 ° C., so that to soften the protective film 16 and the adhesive layer 18 and to have a slight adhesion of the adhesive layer 18 to the blade body 12.

The bonding method also comprises a step of heating the protective film 16 and the adhesive layer 18 to a second activation temperature of the adhesive layer 18, the second activation temperature of the adhesive layer. 18 being greater than the polymerization temperature of the adhesive layer 18. At the second activation temperature, the polymerization of the adhesive layer 18 begins.

The heating of the protective film 16 and the adhesive layer is, for example, carried out by means of an infrared lamp 56, as shown in FIG. 10. In FIG. 10, the infrared lamp 56 is mounted on a movable surface. beam 54, the beam 54 itself being displaceable in a direction horizontal and perpendicular to the direction of movement of the infrared lamp 56 on the beam 54.

The bonding process then comprises a step of pressing the protective film 16 and the adhesive film 18 on the blade 10.

[YES] In FIG. 11, the pressing step is carried out by means of a pressing tool movably mounted on the beam 54. The pressing tool comprises a roller 58 mounted on a return element 60, for example a spring in compression. The roller 58 is made of a deformable material that can adapt to the different curvatures of the blade body 12. The return element 60 makes it possible to maintain a permanent contact between the roller 58 and the protective film 16. It also makes it possible to apply a pressure on the protective film 16 and the adhesive layer 18 so as to stick the protective film 16 on the blade body 12. The roller 58 thus makes it possible to press the protective film 16 and the adhesive layer 18 on dawn 10.

Figure 12 shows the step of cutting the positioning tab 30 by means of a cutting tool 62. The cutting of the positioning tab 30 is along a free edge of the edge shield. attack 14.

The cutting tool 62 can also be mounted on the beam 54 and the cutting can be performed at the same time as the pressing.

FIGS. 10 to 12 show the extrados of the blade 10. However, a protective film 16 also protects the underside of the blade body 12.

The protective film 16 may be glued to the underside of the blade body 12 by repeating the previously described steps.

The protective film 16 may also be formed in one piece and be positioned on the upper and lower surfaces of the blade 10, a first positioning tab 30 being disposed on the extrados of the edge shield. 14 and a second positioning tab 30 being disposed on the underside of the leading edge shield 14.

In Figures 10 and 11, the lamp 56 and the pressing tool are movably mounted on the beam 54. However, the lamp 56 and the pressing tool could be fixedly mounted on the beam 54 and the beam 54 could move in two perpendicular directions in a horizontal plane.

The protective film 16 is bonded to the blade body 12 by means of the adhesive layer 18 and protects the blade body 12 including abrasion.

Thus, a blade 10 is obtained whose blade body 12 not protected by the leading edge shield 14 is protected by the protective film 16.

In what follows, the elements common to the various embodiments are identified by the same reference numerals.

In the bonding process described above, the coating of the adhesive layer 18 on the protective film 16 is performed before the step of shaping the protective film 16 and the adhesive layer 18.

However, one can also consider performing the coating step simultaneously with the shaping step.

Also, the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are disposed separately on the impressions 32, 44. The protective film 16, the adhesive layer 18 and the non-adhesive release film 20 may also be arranged together on the impression although the protective film 16, the adhesive layer 18 and the non-adhesive release film 20 are not secured to each other. It can also be envisaged that the non-adhesive release film 20 is already positioned on the adhesive layer 18 and adheres to it sufficiently to be able to be handled with the adhesive layer.

The other steps are similar to those described above for the shaping of the protective film 16 and the bonding of the protective film 16 to the blade body 12.

A blade 10 is obtained whose blade body 12 not protected by the leading edge shield 14 is protected by the protective film 16.

In the embodiment of FIG. 13, the first activation temperature is greater than or equal to the polymerization temperature of the adhesive layer 18 and the imprint is formed by the blade 10, more specifically by the blade body 12. The impression being formed by the blade 10, it will therefore position and directly paste the protective film 16 on the blade body by means of the adhesive layer 18. The shaping of the film protection is performed directly on the blade body 12 which reduces the number of handling of the protective film 16.

The adhesive layer 18 may be coated on the protective film 16 in a similar manner before forming the protective film 16, as has been previously described with reference to FIGS. 3 and 4.

In Figure 13, the non-adhesive release film 20 has been removed, the protective film 16 and the adhesive layer 18 have been positioned on the blade body 12. The positioning of the protective film 16 is relatively easy since the protective film 16 can be manipulated by the positioning tab 30 and the positioning of the protective film 16 may be less accurate than when the protective film 16 does not include a positioning tab.

In the embodiment of FIG. 13, the protective film 16 is all around the blade body 12 and covers the edge opposite the edge covered by the leading edge shield 14. The protective film 16 therefore comprises at least two positioning tabs 30, each positioning tab 30 at least partially covering a portion of the leading edge shield 14.

Furthermore, the blade body 12 being at ambient temperature, the adhesive layer 18 adheres little to the blade body 12 which allows to easily reposition the protective film 16 when a defect such as a air bubble or crease is detected.

The blade 10, on which the protective film 16 has been positioned is disposed in a deformable pocket 64 forming an enclosure which is then evacuated, for example a secondary vacuum. The pressing of the protective film 16 and the adhesive layer 18 on the blade body 12 is obtained by evacuation of the deformable bag 64.

This deformable pocket 64 has a large deformation capacity of up to several hundreds of percent or even a few thousand. Moreover, the deformable pocket 64 makes it possible to adapt to several different blade geometries 10. Indeed, the vacuum will press the deformable pocket 64 on the blade 10 regardless of the shape of the blade 10 and press the protective film 16 and the adhesive layer 18 on the blade body 12 relatively uniformly .

The heating step begins after the pressing step, that is to say once the deformable pocket 64 evacuated.

The heating of the protective film 16 and the adhesive layer 18 at the first activation temperature of the adhesive layer 18, which is in this embodiment greater than or equal to the polymerization temperature of the coating layer. adhesive 18, allows an improved bonding of the protective film 16 on the blade 10. The heating temperature being at least equal to the polymerization temperature of the adhesive layer 18, the adhesive is cured and bonded between the protective film 16 and the dawn 18 is realized.

The heating can be achieved by means of an infrared lamp, a heating mat, a heat transfer fluid or in an oven.

Air is introduced into the deformable pocket 64 and the temperature of the blade 10 is lowered to room temperature. The blade 10 is removed from the deformable bag 64 and the positioning tabs 30 are cut and removed, for example by means of the cutting tool 62 of FIG. 12.

Thus, a blade 10 is obtained whose blade body 12 not protected by the leading edge shield 14 is protected by the protective film 16.

In the embodiment of FIG. 14, the first activation temperature is greater than or equal to the polymerization temperature of the adhesive layer 18 and the imprint is formed by the blade 10, more specifically by the dawn body 12.

However, the embodiment of FIG. 14 differs from the embodiment of FIG. 13 in that the blade 10, on which the adhesive layer 16 and the protective film 18 are positioned, is arranged in a mold of which a first shell 66 maintains the positioning of the protective film 16 thanks to the positioning tabs 30 and a second shell 68 comprises a flexible membrane 72 defining with the second shell 68 a chamber 72. A gas or a liquid under pressure can to be injected into the chamber 72 to press the flexible membrane 72 against the protective film 16. The pressure is applied to the protective film 16 and the adhesive layer 18 by the flexible membrane 72 pressurized. The pressure is therefore applied relatively uniformly over the entire surface of the protective film 16.

The heating of the protective film 16 and the bonding of the protective film on the blade body 12 by means of the adhesive layer 18 can be obtained by means of the gas or the liquid under pressure in the chamber 72.

Thus, a blade 10 is obtained whose blade body 12 not protected by the leading edge shield 14 is protected by the protective film 16.

Furthermore, there is shown in Figure 15 a fixed blade 74 of the rectifier. This fixed blade comprises a leading edge 76 and a blade body 78 as well as platforms for fixing the fixed blade 80. The protective film 16 and the adhesive layer 18 are positioned on the blade body 78 .

FIG. 16 shows an inter-aerial platform portion 82, such as an inter-fan blade platform of a turbojet engine. This platform comprises parts 84 on the hook that allow the attachment of the inter-blade platform and a stiffener 86. The protective film 16 and the adhesive layer 18 are positioned on the inter-blade platform 82.

FIG. 17 shows an acoustic panel 88 comprising orifices 90 for fixing the acoustic panel 88. The protective film 16 and the adhesive layer 18 are positioned on one face of the acoustic panel 88.

Although the present invention has been described with reference to a specific embodiment, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In addition, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

For example, there is shown a single roller 58 in Figure 11, it is also possible to consider using several rollers 58, each roller 58 being mounted on a return member 60.

When the first activation temperature is lower than the polymerization temperature of the adhesive layer, the third activation temperature may be equal to or different from the first activation temperature. However, the third activation temperature is always lower than the polymerization temperature of the adhesive layer.

The examples have been described with a blade 10. It is understood that this method can also be applied to other three-dimensional parts comprising at least one radius of curvature.

Claims (12)

1. A method of bonding a protective film (16) to a three-dimensional piece (10) comprising at least one radius of curvature, characterized in that the method comprises the following steps: positioning of the protective film (16) and a layer of adhesive (18) on an impression (12; 32; 44; 48) at least partially reproducing a surface of the three-dimensional part (10) or a surface complementary to the three-dimensional part (10), the protective film (16) having at least one locating tab (30) of the protective film (16) and the adhesive layer (18) on this surface; heating the protective film (16) and the adhesive layer (18) at a first activation temperature of the adhesive layer (18); pressing the protective film (16) and the adhesive layer (18) against each other on the cavity (12; 32; 44; 48) to form the protective film (16) on the imprint (12; 32; 44; 48); cooling of the protective film (16) at ambient temperature; - Cutting of the positioning tab (30). 2. Method according to claim 1, wherein the first activation temperature is lower than a polymerization temperature of the adhesive layer (18), the heating is achieved by the impression (44; 48) and the adhesive layer. (18) carries, on a surface opposite a surface in contact with the protective film (16), a non-adhesive release film (20). 3. The method of claim 2, wherein the cavity (32) directly reproduces at least partially the surface of the three-dimensional part (10), the non-adhesive release film (20) being in contact with the cavity (32). 4. The method of claim 2, wherein the cavity (44; 48) at least partially reproduces a surface complementary to the surface of the three-dimensional part (10), the protective film (16) being in contact with the impression. (44; 48). A method according to claim 3 or 4, wherein the imprint (32; 44), on which the non-adhesive release film (20), the adhesive layer (18) and the protective film (16) are positioned, is disposed in an enclosure (34, 40; 44, 46) having a flexible membrane (42; 46), and the protective film (16) and the adhesive layer (18) are pressed against each other on the impression (32; 44) by the flexible membrane (42; 46). 6. The method of claim 4, wherein the positioning of the protective film (16) and the adhesive layer (18) is done by gluing the positioning tab (30) on an inflatable bladder (48) and the bladder. inflatable (48) is inflated to form the impression. A method according to any one of the preceding claims, wherein after cooling the protective film (16), the shaped protective film (16) is stored. The method of any one of claims 2 to 7, further comprising the steps of: removing the non-adhesive release film (20); positioning the protective film (16) shaped on the three-dimensional part (10); heating the protective film (16) and the adhesive layer (18) to a second activation temperature of the adhesive layer (18), the second activation temperature being greater than or equal to the polymerization temperature of the adhesive layer (18); - Bonding the protective film (16) on the three-dimensional part (10) by pressing the protective film (16) and the adhesive layer (18) on the three-dimensional part (10). The method of claim 1, wherein the first activation temperature is greater than or equal to a polymerization temperature of the adhesive layer (18) and the imprint is the three-dimensional part (10). The method of claim 9, wherein the heating step begins after the pressing step. The method according to claim 10, wherein the three-dimensional part (10), on which the adhesive layer (18) and the protective film (16) are positioned, is disposed in a deformable bag (64) and the pressing of the protective film (16) and the adhesive layer (18) on the three-dimensional part (10) is obtained by evacuation of the deformable bag (64). 12. The method of claim 9 or 10, wherein the three-dimensional piece (10), on which are positioned the adhesive layer (18) and the protective film (16), is arranged in a mold, a first shell (66). ) maintains the positioning of the protective film (16) by means of the positioning tab (30) and of which a second shell (68) comprises a flexible membrane (70), and the protective film (16) and the adhesive layer ( 18) are pressed against each other on the three-dimensional part (10) by the flexible membrane (70).