Device and method for machining fan blades

Abstract

A method for removing an attachment to the leading edge (5) of a fan blade (4) is disclosed, the fan blade (4) comprising a first material and the leading edge (5) comprising a second material different from the first material, the method comprising the step of determining the thickness of the leading edge (5) according to the position on the leading edge (5), and the step of removing the leading edge (5) by means of a pressurized water jet (J) moving above the leading edge (5) according to the thickness determined in the determining step.

Description

Technical Field

[0001] The present invention relates to the field of aviation turbines, and more particularly to the repair or rework of turbine fan blades, and in particular to a method and device for removing material from the surface of these blades. Background Art

[0002] In fields such as aviation, aircraft weight reduction is a constant concern for manufacturers. For example, in aircraft engines, it is known to replace some metal blades with blades made of composite materials, which have the advantage of being lighter.

[0003] Although these materials generally have very good mechanical qualities, especially in relation to their mass, they are somewhat sensitive to point impacts.

[0004] For example, for fan blades made of organic matrix composites, metal leading edges are added to the ends of these blades, which allow an increase in the resistance to point impacts to which this part of the blade is subjected. These metal leading edges serve as shields and take the form of, for example, thin inner-arc fins and thin outer-arc fins connected at the upstream end of the blade, the whole conforming to the shape of the blade on the leading edge and to the adjacent sections of the inner arc and the outer arc.

[0005] However, the accumulation of flight hours and the potential repeated impacts of foreign objects cause wear on these metal leading edges, which requires their repair or replacement.

[0006] There are different solutions for removing the metal leading edge from the rest of the blade, such as mechanical tearing or thermomechanical tearing. However, the disadvantage of these solutions is that they can damage the composite fibers of the blade to which the leading edge is fixed. Conventional machining solutions can also be envisaged, but especially due to the distortion and complex shape of the blade surface, complex computer tools and devices are required.

[0007] Therefore, a material removal method that overcomes the above disadvantages is needed. Summary of the Invention

[0008] The present disclosure relates to a method for removing a component fixed to an aviation part, the aviation part comprising a first material and the component comprising a second material different from the first material, the method comprising the following steps:

[0009] - determining the thickness of the component according to the position on the component,

[0010] - removing the component by means of a pressurized water jet moving on the component according to the thickness determined in the determining step.

[0011] It is understood that the part is an element different from the aviation part and is added to the aviation part by being fixed to the aviation part. The determination step allows mapping the thickness of the part. In other words, this step allows determining the thickness of the part at a given position on the outer surface of the part. Therefore, this step allows determining the thickness of the material to be removed.

[0012] The removal step allows removing the part by means of a pressurized water jet. The high pressure of the water jet serves as a machining tool, allowing removal of the material contained in the part. Therefore, for a given position on the surface of the part, the water jet removes the thickness of the part material determined in the determination step.

[0013] Knowing the thickness of the material to be removed, using a pressurized water jet allows removing the part from the aviation part without affecting the aviation part. In other words, the method allows removing the first material contained in the part while limiting direct contact with the second material contained in the aviation part, which may be the case with machining tools. Therefore, it is possible to not damage the aviation part by limiting the risk of deterioration of the second material. Using a pressurized water jet also has the advantage of simplifying the method for removing material from a part with a complex-shaped surface.

[0014] In some embodiments, the first material is an organic matrix composite and the second material is a metal.

[0015] In other words, the aviation part includes an organic matrix composite, and the part fixed to the aviation part includes a metal. The method allows removing the metal from the part without damaging the organic matrix composite, especially without damaging the fibers of the composite.

[0016] In some embodiments, before removing the part, the part is fixed to the aviation part by adhesion.

[0017] "Before removing the part" means before performing the method, that is, before the part must be removed, for example, when it must be replaced in case of wear of the part. For example, the part can be fixed to the aviation part by a structural epoxy adhesive. If the part is removed by, for example, mechanical tearing, this fixing method may pose a risk of damaging the fibers of the composite material of the aviation part. Using a pressurized water jet allows overcoming this drawback.

[0018] In some embodiments, the pressure of the water jet is between 100 bar and 1000 bar.

[0019] This pressure value range allows effective removal of the part.

[0020] In some embodiments, the ejected water includes an abrasive medium.

[0021] The pressure of the water jet used, combined with the presence of the abrasive medium, generates numerous impacts on the part, and these impacts cause particles of a second material, especially metal, contained in the part to exit. Thus, the presence of the abrasive medium allows for an increase in the efficiency of the part removal method.

[0022] In some embodiments, the abrasive medium has a particle size included between 50 microns and 1 millimeter.

[0023] The abrasive medium may include solid particles present in water intended to be sprayed under pressure, and the diameter of these particles is included between 50 microns and 1 millimeter. Values below 50 microns would limit the efficiency of the removal method, and values above 1 millimeter would be incompatible with the pressurized water spraying tools used within the framework of this method.

[0024] In some embodiments, the abrasive medium is sand including one of pure silica and silicon carbide.

[0025] In some embodiments, the water jet is applied by means of a nozzle oriented such that it forms an angle with respect to the normal to the plane tangent to the part surface at the point where the water jet is applied, and this angle is included between + / −15° and + / −25°, preferably equal to + / −20°.

[0026] For example, if the part is a flat plate, the angle between the nozzle and the pressurized water jet applied to the plate is between + / −15° and + / −25°, for example, an angle of + / −20° with respect to the direction perpendicular to this plate. Compared with the case where the water jet is oriented perpendicular to the plate, this inclination of the water jet allows for optimizing the removal of the part material.

[0027] In some embodiments, the nozzle applying the water jet is arranged at a distance less than or equal to 20 centimeters from the part.

[0028] Thereby, direct contact between the removal device and the aviation part can be avoided. In addition, a distance greater than 20 centimeters would generate a dispersed water jet, thereby losing the accuracy of the water jet during the removal step.

[0029] In some embodiments, the thickness of the part is determined via ultrasound according to the position on the part.

[0030] For example, a scan of the entire outer surface of the part can be performed using a tool that emits ultrasound. At each position of the tool on the part surface, the signal transmitted by the tool that emits ultrasound is converted into thickness. This ultrasonic analysis can be performed especially by echolocation.

[0031] During the use of an aviation part, the wear generated on the part is uneven, such that when the part is removed, the thickness of the part itself is also uneven. The thickness of the part is determined according to the position on the part via ultrasonic waves, thereby allowing the thickness of the material to be removed at each position to be known, and thus adjusting the pressurized water jet according to the thickness to be removed, for example, by adapting the pressure of the water jet.

[0032] In some embodiments, during the removal step, the displacement speed of the water jet moving above the part is constant, and the pressure of the water jet varies according to the thickness to be removed.

[0033] According to this configuration, the thickness of the part determined in the determination step is converted into pressure. During the displacement of the water jet on the outer surface of the part at a constant speed, for example, when the local thickness of the part is low, the pressure is then reduced. Conversely, when the local thickness is high, the pressure of the water jet increases. The advantage of this removal method is that the method can be carried out by only changing one parameter (here the pressure), thus simplifying the processing control.

[0034] In some embodiments, during the removal step, the displacement speed of the water jet moving above the part varies according to the thickness to be removed, and the pressure of the water jet is constant.

[0035] According to this configuration, the thickness of the part determined in the determination step is converted into speed. During the displacement of the water jet on the outer surface of the part at a constant pressure, for example, when the local thickness of the part is low, the displacement speed is then reduced. Conversely, when the thickness is locally high, the displacement speed of the water jet is reduced so that the water jet has time to remove the entire thickness of the part at this position. The advantage of this removal method is that the method can be carried out by only changing one parameter (here the speed), thus simplifying the processing control.

[0036] In some embodiments, during the removal step, the displacement speed and the pressure of the water jet moving above the part vary according to the thickness to be removed.

[0037] According to this configuration, the thickness of the part determined in the determination step is converted into a pair of speed / pressure parameters.

[0038] In some embodiments, during the removal step, the displacement speed and the pressure of the water jet moving above the part are constant, and the number of channels of the water jet varies according to the thickness to be removed.

[0039] Under this configuration, the thickness of the part determined in the determination step is converted into the number of water jet channels required at the given position according to the thickness at the given position. For example, at a constant speed and pressure, the greater the thickness at a given position will result in more channels required at that position, and vice versa.

[0040] In some embodiments, a suction tool sucks the material removed during the removal step.

[0041] The device may be arranged near a water jet nozzle, for example less than 10 cm away. The suction tool allows sucking the debris of the component material removed by the water jet during the removal step.

[0042] In some embodiments, the water jet moves on the component by means of a swiveling tool comprising at least two axes of rotation.

[0043] In some embodiments, the water jet moves on the component by means of a swiveling tool comprising only two axes of rotation.

[0044] The swiveling tool may be a robot, which comprises at least two arms swiveling relative to each other, and a nozzle for jetting the water jet is arranged at one end of one of the arms. By rotating the nozzle around only two axes of rotation by means of the swiveling tool, it has the advantage of simplifying the removal method, especially for parts with complex surfaces. For example, for a twisted surface, a machining tool needs to rotate around five different axes to adapt to this twisted shape and the variable thickness of the component. Using a pressurized water jet allows limiting the necessary number of axes of rotation, thus simplifying the removal method.

[0045] In some embodiments, after the removal step, the method comprises a step of polishing the aircraft part obtained by the removal step.

[0046] The polishing step may include manually or mechanically sanding the residual glue after the removal step. This step allows standardizing and smoothing the surface of the obtained aircraft part from which the component fixed thereto has been removed, so as to obtain a roughness close to that of a new part. This makes it particularly easy to fix a new component to the aircraft part.

[0047] In some embodiments, the aircraft part is a fan blade and the component is the leading edge of the blade.

[0048] The method allows determining the thickness of the metallic leading edge according to the position on the leading edge, and then removing the leading edge by means of a pressurized water jet without damaging the fan blade to which the leading edge is fixed, that is, limiting the risk of damage to the organic matrix composite fibers contained in the blade. In addition, the implementation of this method uses a water jet directed and scanned on the surface of the leading edge by a two-axis robot, which is particularly suitable for the twisted shape of the fan blade.

[0049] The present disclosure also relates to a device for removing a component fixed to an aircraft part, the aircraft part comprising a first material, and the component comprising a second material different from the first material, the removal device comprising a measuring tool and a pressurized water spraying tool, the measuring tool being configured to measure the thickness of the component according to the position on the component, and the pressurized water spraying tool being configured to remove the component by moving above the component according to the thickness determined by the measuring tool by means of a pressurized water jet. Description of the Drawings

[0050] The present invention and its advantages will be better understood by reading the following detailed description of various embodiments of the present invention given by way of non - limiting examples. This description refers to the attached drawing pages, in which:

[0051] Figure 1 is a schematic perspective view of a turbofan engine,

[0052] Figure 2 is Figure 1 a schematic perspective view of the rotating blades of the fan of a turbojet engine of

[0053] Figure 3 is Figure 2 a sectional view of the blade of

[0054] Figure 4 a schematic view of a removal device according to an embodiment,

[0055] Figure 5 is by means of Figure 4 a detailed schematic view of the removal step by the device of

[0056] Figure 6 is Figure 4 a sectional view of the blade of

[0057] Figure 7 is a diagram showing a removal method according to the present disclosure. Detailed Description of the Invention

[0058] Figure 1 A turbofan engine 1 is shown, which includes a gas generator unit 2 and a fan 3. The fan 3 includes a plurality of rotating blades 4, which are radially arranged around a central axis X and are aerodynamically contoured to push air by their rotation. Thus, as Figure 2 shown, each blade 4 has a leading edge, a trailing edge 6, an outer arc surface 7 and an inner arc surface 8.

[0059] During normal operation, the relative wind is substantially directed towards the upstream end of each blade 4 along the air flow direction in the fan. This upstream end is particularly vulnerable to impact and wear. Especially when the blade 4 includes composite materials, particularly with a fiber - reinforced polymer matrix, it is therefore necessary to use a protection fixed to the leading edge 5 of each blade 4 to protect this upstream end of the blade 4.

[0060] The leading edge 5 is a part or component added to the upstream end of the blade 4 along the direction of the airflow in the fan and conforms to the shape of the upstream end of the blade 4. In other words, the leading edge 5 is assembled on the blade 4. This assembly can be carried out by adhesion, for example, by a structural epoxy adhesive. The leading edge 5 is made of a material that is more resistant to point impact than the composite material of the blade 4. More specifically, the leading edge 5 is mainly metallic, more specifically made of a titanium-based alloy such as TA6V (Ti-6Al-4V). The leading edge 5 can also be made of steel or iron, chromium, and nickel-based alloys such as and so on.

[0061] The outer surface 5A of the leading edge 5 is thus exposed to impacts and wear, thereby protecting the composite material of the blade 4. The accumulation of flight hours causes wear of this leading edge. This wear, as well as the impacts that cause this wear, is uneven, and the thickness of the leading edge 5A itself is uneven. Figure 3 is Figure 2 a cross-sectional view of the blade taken along plane III-III and shows an example of the variation of the thickness of the leading edge 5 according to the position on the outer surface 5A of the leading edge 5.

[0062] When the leading edge 5 is significantly worn, it is necessary to remove the leading edge 5 in order to replace it with a new one. This removal is feasible with the removal device described with reference to Figure 4 hereinafter, the removal device includes a pivoting tool 30, for example a robot, the pivoting tool 30 including, for example, at least one first arm 31, at least one second arm 32, and a tool holder 33, the first arm 31 being fixed to the ground, the second arm 32 pivoting relative to the first arm 31 about a first axis of rotation 30A, and the tool holder 33 pivoting relative to the second arm 32 about a second axis of rotation 30B.

[0063] The disassembly device further includes a control unit 40 connected to the pivoting tool 30 and controlling the movement of the pivoting tool 30. A measuring tool 20 can be fixed to the tool holder 33 and is configured to detect the thickness of the leading edge 5. The measuring tool 20 can be an ultrasonic thickness gauge. The measuring tool 20 is connected to the control unit 40. The control unit 40 can be a human-machine interface that is capable of converting a geometric path in space into a line of machine code to control the arms of the pivoting tool 30.

[0064] The removal device further includes a pressurized water spraying tool 10. The pressurized water spraying tool includes a high-pressure pump (not shown) and a spray nozzle 12 connected to the pump. The pressurized water spraying tool 10 is configured to spray a fine water stream at a pressure included between 100 bar and 1000 bar by means of the spray nozzle 12. The water present in the pump and intended to be sprayed by the spray nozzle 12 can be mixed with a grinding medium having a particle size included between 50 microns and 1 mm. The grinding medium can be pure silica or silicon carbide. The water spraying tool 10 is connected to the control unit 40. Thus, the control unit 40 can adjust the pressure of the water sprayed by the water spraying tool 10.

[0065] The water spray nozzle 12 and the measuring tool 20 can be fixed to the tool holder 33 simultaneously. Alternatively, the water spray nozzle 12 and the measuring tool 20 can be fixed to the tool holder 33 successively. More specifically, at the end of the first step of the method described below, the measuring tool 20 can be removed from the tool holder 33 and replaced with the water spray nozzle 12 to perform the second step.

[0066] The removal device may further include a suction tool 50, which includes a suction pipe 52, and one end of the suction pipe 52 is fixed to the tool holder 33 near the injection nozzle 12. The suction tool 50 can be a suction device configured to suck debris and liquid, and its power is between 1500 and 2500 W.

[0067] The following refers to Figures 5 to 7 Describe the removal method.

[0068] The first step (step S1) allows determining the thickness of the leading edge 5 according to the position on the leading edge 5, that is, for a given point on the outer surface 5A of the leading edge 5.

[0069] During step S1, the control unit 40 controls the pivoting tool 30 so that the measuring tool 20 arranged opposite the leading edge 5 is moved by emitting ultrasonic waves to scan the entire outer surface 5A of the leading edge 5 along a predetermined path. Then the data measured by the measuring tool 20 is transmitted to the control unit 40, and the control unit 40 converts these data into thickness. Therefore, at the end of step S1, the thickness of the leading edge 5 is known, that is, the mapping of the leading edge thickness at each given point on the outer surface 5A.

[0070] The second step (step S2) allows removing the leading edge 5 of the blade 4. To this end, the control unit 40 converts the thickness measured during the first step S1 into pressure. Then, the control unit 40 controls the pivoting tool 30 so that the water spray nozzle 12 arranged opposite the leading edge 5 is moved by following the same path as the measuring tool during step S1 to scan the entire outer surface 5A of the leading edge 5. During this scan, the injection nozzle 12 arranged on the tool holder 33 moves at a constant speed v0, and the pressure p of the water sprayed by the nozzle 12 varies according to the thickness of the leading edge 5 based on the conversion performed by the control unit 40.

[0071] While performing this removal step, the debris or particles of the leading edge 5 removed by the water jet J can be sucked through the suction tool 50 by means of the suction pipe 52 also arranged on the tool holder 33. Alternatively, the debris suction can be performed at the end of step S2.

[0072] During step S2, in order to improve the machining accuracy by avoiding excessive dispersion of the water jet J, during the displacement of the nozzle 12, the distance Δ between each contact point between the end of the nozzle 12 and the outer surface 5A of the nozzle J and the leading edge 5 is kept less than or equal to 20 cm.

[0073] In addition, the angle β between the jet J and the line perpendicular to the plane P that is tangent to the outer surface 5A at the contact point between the jet J and the surface 5A and passes through this contact point is included between + / - 15° and + / - 25°.

[0074] In addition, during step S2, the water jet J scans the outer surface 5A of the leading edge 5 by means of the pivoting tool 30 controlled by the control unit 40. The control unit 40 controls in particular the rotation axes 30A and 30B. Thus, by controlling these two rotation axes, the injection nozzle 12 can be positioned and oriented relative to the surface 5A, and thus the water jet J can be positioned and oriented.

[0075] The method may include a third step (step S3) of polishing the portion of the fixed leading edge 5 on the surface of the blade 4 after completing step S2. This polishing can be carried out manually or mechanically. This step S3 allows the cleaning of the residual glue joints on the blade 4 to reach a roughness level close to that of a new part, so as to fix the new leading edge 5 on the blade 4.

[0076] The above method gives an embodiment according to which the leading edge is removed by scanning the surface 5A by moving the nozzle 12 at a constant speed v0 and varying the pressure p of the water jet according to the position on the surface 5A and based on the transformation carried out by the control unit 40. However, other embodiments can be envisaged.

[0077] For example, during step S2, the control unit 40 can convert the thickness measured during step S1 into the displacement speed v of the nozzle 12. Thus, the surface 5A is scanned to perform the step of removing the leading edge by moving the nozzle 12 at a constant pressure p0 at a speed that varies according to the position on the surface 5A and based on the transformation carried out by the control unit 40.

[0078] According to another example, both the displacement speed of the nozzle 12 and the pressure of the water jet J can vary according to the thickness of the leading edge 5. To this end, the thickness determined in step S1 is converted into a speed / pressure pair (v, p).

[0079] According to yet another example, the removal step can also be carried out at a constant speed and pressure. To this end, the removal thickness determined in step S1 is converted into multiple passes, that is, the number of passes required for the water jet J at a given point on the surface 5A at a constant speed v0 and pressure p0 according to the thickness of the leading edge 5 at this point.

[0080] Although the present invention has been described with reference to specific exemplary embodiments, it is apparent that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. Specifically, the various features of the different embodiments illustrated / mentioned can be combined into additional embodiments. Accordingly, the specification and drawings should be considered in an illustrative rather than a restrictive sense.

[0081] It is also apparent that all features described with reference to a method can be transferred, individually or in combination, to an apparatus, and vice versa, all features described with reference to an apparatus can be transferred, individually or in combination, to a method.

Claims

1. A method for removing a leading edge (5) fixed to a fan blade (4), using a pivoting tool (30), the pivoting tool including at least one first arm (31), at least one second arm (32), and a tool holder (33), the second arm being pivoted relative to the first arm (31) by a first rotation axis (30A), the tool holder being pivoted relative to the second arm (32) by a second rotation axis (30B), the fan blade (4) including a first material, the leading edge (5) including a second material different from the first material, the method comprises the following steps: - determining the thickness of the leading edge (5) according to the position on the leading edge (5) by means of a measuring tool (20) fixed to the tool holder (33); - removing the leading edge (5) according to the thickness determined in the determining step by means of a pressurized water jet tool (10), the pressurized water jet tool having a spray nozzle (12) fixed to the tool holder (33) and configured to remove the leading edge (5) by means of a pressurized water jet (J) moving above the leading edge (5); - sucking the material removed during the removing step by means of a sucking tool (50), the sucking tool including a sucking pipe (52), one end of the sucking pipe being fixed to the tool holder (33) near the spray nozzle (12).

2. The method according to claim 1, characterized in that the first material is an organic matrix composite and the second material is a metal.

3. The method according to claim 1, characterized in that the pressure of the water jet (J) is between 100 bar and 1000 bar.

4. The method according to claim 1, characterized in that the sprayed water includes an abrasive medium.

5. The method according to claim 1, characterized in that the water jet (J) is applied by means of the nozzle (12), the nozzle (12) being oriented such that an angle (β) is formed with respect to the normal of a plane (P) tangent to the surface (5A) of the leading edge (5) at the point where the water jet (J) is applied, the angle being between 15° and 25°.

6. The method according to claim 5, characterized in that the angle is equal to 20°.

7. The method according to claim 1, characterized in that determining the thickness of the leading edge (5) according to the position of the leading edge (5) is performed via ultrasonic waves.

8. The method according to claim 1, characterized in that during the removing step, the displacement speed of the water jet (J) moving above the leading edge (5) is constant, while the pressure of the water jet (J) varies according to the thickness to be removed.

9. The method according to claim 1, characterized in that during the removing step, the displacement speed of the water jet (J) moving above the leading edge (5) varies according to the thickness to be removed, while the pressure of the water jet (J) is constant.

10. The method according to claim 1, characterized in that after the removing step, the method further includes a step of polishing the fan blade (4) obtained from the removing step.

11. A device for removing a leading edge (5) fixed to a leading edge of a fan blade (4), the fan blade (4) comprising a first material, the leading edge (5) comprising a second material different from the first material, the removing device comprising a measuring tool (20), a pressurized water jet tool (10), a suction tool (50) and a pivoting tool (30), the measuring tool being configured to determine the thickness of the leading edge (5) according to a position on the leading edge (5), the pressurized water jet tool (10) comprising a jet nozzle (12) being configured to remove the leading edge (5) according to the thickness determined by the measuring tool (20) by means of a pressurized water jet (J) moving above the leading edge (5), the suction tool comprising a suction pipe (52) configured to suck the material removed through the jet nozzle (12), the pivoting tool comprising at least one first arm (31), at least one second arm (32) and a tool holder (33), the second arm being pivoted relative to the first arm (31) by means of a first rotation axis (30A), the tool holder being pivoted relative to the second arm (32) by means of a second rotation axis (30B), the measuring tool (20), the jet nozzle (12) and the suction pipe (52) being fixed to the tool holder (33).

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