Method for repair welding of aircraft turbine engine blades

Abstract

The invention relates to a method for repair welding of an aircraft turbine engine blade (102), the blade comprising a lower surface and an upper surface connected by a leading edge (106) and a trailing edge (104), the blade further comprising a free end portion referred to as a tip portion (108), the method comprising repair welding the tip portion and comprising the following steps: - fixing a first stopper (110) to the leading edge at the tip portion and fixing a second stopper (112) to the trailing edge at the tip portion, - depositing a repair weld bead on the tip portion from the first stopper to the second stopper, and - removing the first stopper and the second stopper, the method being characterized in that the first stopper and the second stopper are fixed only by pressing the first stopper and the second stopper against the leading edge and the trailing edge.

Description

Technical Field

[0001] The present invention relates to the field of aircraft turbine engines and in particular to the repair of the tip portion of a blade of a one-piece bladed disk (known by its French acronym DAM) of a GE 90-115K engine. More specifically, the object of the invention is to enable the implementation of repair welding of blades in the context of new developments in additive manufacturing repair technology (LMD, acronym for “Laser Metal Deposition”). Background Art

[0002] The technical background includes in particular the documents DE 42 37 052 ​​A1, DE 10 2009 043136 A1 and DE 195 47903 C1.

[0003] In a known manner, for the repair of the blade tip portion of an integral blade disk, the repair welding of the tip portion is performed by an additive manufacturing method achieved by powder deposition and melting, which is also called the LMD-p method (abbreviation for “Laser Metal Deposition-powder”).

[0004] The repair welding of the end portion is a linear repair welding performed from the leading edge of the blade to the trailing edge of the blade. The linear repair welding necessarily includes the starting point and the end point of the weld.

[0005] Issue to be addressed: The start and end areas of a weld bead are considered sensitive from a metallurgical health perspective and may contain defects such as lack of bond or collapse, which are unacceptable from both a technical and quality perspective.

[0006] The main causes of the defects arise, on the one hand, from the geometry of each end of the blade (related to the radius of the leading edge) and, on the other hand, from the thickness of each end of the blade (leading edge or trailing edge).

[0007] To avoid finding these sensitive areas in the finished component, stops are used.

[0008] These stop elements are sacrificial parts, ie sacrificial objects, which are usually fastened to the blade by means of welding methods, in particular by spot welding.

[0009] The attachment of the stop to the blade must be sufficient (e.g. by penetration welding) to ensure that the stop remains in place during the repair welding while avoiding the risk of sticking (which must also be limited to a minimum) so as not to affect the final component metallurgically and dimensionally. The metallurgically affected area of ​​the finished component is called the heat affected zone; the dimensionally affected area of ​​the finished component is called the blade deformation zone.

[0010] The stops used hitherto, also known as spot welding stops, are based on the geometry of standard stops.

[0011] Figure 1 An integrated blade disk 10 consisting of a plurality of blades 12 according to the prior art is shown, on which stoppers 14a, 14b are arranged. The stopper 14b is arranged on the leading edge 11 of the blade 12, while the stopper 14a is arranged on the trailing edge 13 of the blade 12. The protrusions 16b, 16a around the leading and trailing edges of the pressure and suction sides enable the stoppers 14a, 14b to be spot welded at the blade 12. In particular, the protrusion 16b surrounds the leading edges of the pressure and suction sides of the blade 12, while the protrusion 16a surrounds the trailing edges of the pressure and suction sides of the blade 12. The pressure side of the blade 12 of the integrated blade disk 10 is Figure 1 and dashed box B, while the suction side of the blade 12 is shown in dashed box C.

[0012] However, the balance between making the spot welds penetrating enough to ensure good retention of the stopper and making the spot welds light enough to avoid recession areas (ie heat affected zones) on the blade has not yet been found.

[0013] In fact, during the first repair welding, the stops systematically collapsed, resulting in unacceptable radiographic indications.

[0014] For example, Figure 2 A blade 12 of an integral blade disk is shown collapsed during repair welding using the LMD-p process. In this figure, line A represents the collapse of the trailing edge of the blade 12.

[0015] Several tests were carried out to avoid blade collapse of one-piece blade disks during repair welding by the LMD-p method. The tests were all carried out on three blades. X-ray inspection was carried out after each spot weld to highlight any porosity or linear indications.

[0016] Figure 3a , Figure 3b , Figure 5a , Figure 5b , Figure 7a , Figure 7b , Figure 9a as well as Figure 9b The stop shown in shows a standard geometry stop secured to the blade by spot welding.

[0017] Some have suggested shortening the projection of the stopper to avoid collapse of the stopper. Figure 3a and Figure 3b The blade 12 is shown with Figure 1 A stopper 24 having a shortened protrusion 26 compared to the protrusion in FIG. 2 is fixed to the blade by spot welding.

[0018] Figure 4 Shows Figure 3a and Figure 3b The X-ray image of blade 12, however, Figure 4 As shown, with such a stopper 24, pores as well as linear indications are observed on the radiograph.

[0019] To eliminate underbonding, it is recommended to increase the power at the beginning and end of the weld bead (length of more than 15 mm from leading edge to trailing edge) in the first pass. However, this results in greater penetration at the leading and trailing edges of the blade 12.

[0020] It has also been suggested to lighten the stop while maintaining the same stop geometry. Figure 5a and Figure 5b The blade 12 is shown with a stopper 34 fixed to the blade by spot welding. Figure 1 The stopper reduces weight.

[0021] Figure 6 Shows Figure 5a and Figure 5b The X-ray image of the blade 12 in FIG. Figure 6 As shown, with such a stopper 34, pores and excessive penetration are observed on the radiograph.

[0022] It has also been suggested that the height of the stop should be modified so that the blade tip remains as free as possible and maintains contact with the blade leading edge. Figure 7a and Figure 7b A blade 12 is shown to which a stopper 44 is fixed by spot welding, relative to Figure 1 The height of the stopper 44 at the tip 44 of the blade 12 is changed. Figure 7a , dimension d1 is substantially equal to 3.0 mm and dimension d2 is substantially equal to 0.5 mm.

[0023] Figure 8 Shows Figure 7a and Figure 7b The X-ray image of blade 12, however, Figure 8 As shown, with such a stopper 44, linear indications, bonding problems, and collapsed pores on the leading and trailing edges of the blades are observed on radiographs, these pores being caused by power variations to avoid lack of linear bonding.

[0024] It is also recommended to clean the tip of the blade to avoid loss of connection. Figure 9a and Figure 9b A blade 12 is shown to which a stop 54 is fixed by spot welding. Figure 1The height of the stop 54 is modified to clear the tip of the blade 12 as compared to the stop in FIG.

[0025] However, with such a stopper 54, pores, linear indications and excessive penetration are systematically observed on the radiographs. These drawbacks are caused by the fact that the stopper 54 is spot welded to the blade 12.

[0026] The object of the present invention is to propose a solution that addresses at least some of these drawbacks.

[0027] In particular, the invention proposes to develop a method for fastening a stop to a turbine engine blade, in particular to a blade of an integral blade disk. Summary of the invention

[0028] To this end, the invention relates to a method for repair welding of an aerospace turbine engine blade, said blade comprising a pressure side and a suction side connected by a leading edge and a trailing edge, said blade also comprising a free end portion, known as a tip portion, the method comprising repair welding of said tip portion and comprising the following steps:

[0029] - fixing a first stop to the leading edge at the terminal end and a second stop to the trailing edge at the terminal end,

[0030] - depositing a repair bead on the terminal portion from the first stop to the second stop, and

[0031] - removing the first stop and the second stop,

[0032] The method is characterized in that the first stop and the second stop are fixed only by pressing the first stop and the second stop against the leading edge and the trailing edge.

[0033] The present invention therefore advantageously proposes to eliminate spot welding of the stopper.

[0034] According to the invention, the stopper is held on the stopper by mechanical action, more precisely by compression. This method of attachment advantageously makes it possible to avoid the creation of a heat-affected zone on the blade while ensuring adequate retention. The invention thus makes it possible to eliminate the need for spot welding of the stopper.

[0035] Using the same power for the deposition of the repair bead makes it possible to avoid collapse of the trailing edge or leading edge of the blade and extremely significant penetrations, which would be caused by a change in power between the beginning and the end of the bead.

[0036] According to the invention, the turbine engine blade may be a blade of an integral blade disk.

[0037] According to the invention, the step of depositing the repair bead may be performed by additive manufacturing via powder deposition and melting.

[0038] According to the present invention, the first stopper and the second stopper may be made of the same material as that of the repair weld bead.

[0039] In particular, the first and second stops and the repair weld bead may be made of titanium loaded with 6% aluminum and 4% vanadium (TA6V).

[0040] Advantageously, the use of such a material provides the stopper with high strength and at the same time high ductility.

[0041] According to the present invention, the method may further include: before the step of fixing the first stopper and the second stopper, a step of preheating the first stopper by using a laser.

[0042] According to the invention, the first stopper and the second stopper may have a predetermined stiffness (adjusted for each blade) to apply a force to keep the first stopper and the second stopper pressed against the leading edge and the trailing edge.

[0043] Advantageously, the region of each stop which ensures that the stop is retained on the blade has sufficient rigidity to ensure a spring effect which holds said stop on the blade by compression.

[0044] According to the present invention, the first stopper and the second stopper may each have an undercut portion extending from the tip portion along the front edge and the rear edge, respectively.

[0045] Advantageously, in particular due to the undercut, the portion of the extrusion blade of each stopper is not in contact with the molten repair weld zone, which makes it possible to avoid finding injected material in the repair weld zone.

[0046] According to the present invention, the first stopper and the second stopper can be fixed to the leading edge and the trailing edge with a gap of 0.05 mm or less.

[0047] Therefore, the geometric shapes of the first stopper and the second stopper conform to the shape of the blade to avoid a gap between the stopper and the blade greater than 0.05 mm.

[0048] According to the present invention, the length of the first stopper and the second stopper along the pressure side and / or the suction side may be greater than or equal to 0.5 mm.

[0049] Advantageously, the first and second stops thus have sufficient length in the continuation of the blade, ie at the leading and trailing edges, to ensure a correct start and end of the weld bead.

[0050] The height of the first stopper and the second stopper is sufficient to ensure that the stopper has a good orientation along the leading edge and the trailing edge. For example, the height of the first stopper and the second stopper along the leading edge and the trailing edge, respectively, can be greater than or equal to 1 mm, more precisely greater than or equal to 8 mm, and even more precisely greater than or equal to 10 mm.

[0051] A height difference between the first stopper and the second stopper may be greater than or equal to 0.1 mm.

[0052] According to the present invention, the first stopper and the second stopper may each include a first portion and a second portion arranged opposite to each other, the first portion being arranged on the pressure side and the second portion being arranged on the suction side. In this case, the method may further include, before the step of fixing the first stopper and the second stopper, a step consisting of tightening the first portion and the second portion of each stopper.

[0053] Advantageously, therefore, each stop is adjusted on the blade by tightening the first and second portions of each stop, thereby optimizing the pressing effect of the stop on the blade.

[0054] In particular, when assembling the stopper to the blade, an operator may use a tool such as pliers to adjust the tightness of the first and second parts of the stopper. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention will be better understood and further details, features and advantages of the invention will become more apparent from the following description of non-limiting examples, with reference to the accompanying drawings, in which:

[0056] [ Figure 1 ] has been described Figure 1 The integrated blade disk with a stopper according to the prior art is schematically shown.

[0057] [ Figure 2 ] has been described Figure 2 Shows Figure 1 X-ray photo of the blades of the integrated blade disk,

[0058] [ Figure 3a and Figure 3b ] has been described Figure 3a and Figure 3b shows very schematically a side view and a top view, respectively, of a blade of a one-piece blade disk with a stop according to a first test of the prior art,

[0059] [ Figure 4 ] has been described Figure 4 Shows Figure 3a and Figure 3b X-ray photo of the blades of the integrated blade disk,

[0060] [ Figure 5a and Figure 5b ] has been described Figure 5a and Figure 5b 1 and 2 show very schematically a side view and a top view of a blade of a second test of a one-piece blade disk with a stop according to the prior art,

[0061] [ Figure 6 ] has been described Figure 6 Shows Figure 5a and Figure 5b X-ray photo of the blades of the integrated blade disk,

[0062] [ Figure 7a and Figure 7b ] has been described Figure 7a and Figure 7b 1 and 2 show very schematically a side view and a top view of a blade of a one-piece blade disk with a stop according to a third test of the prior art,

[0063] [ Figure 8 ] has been described Figure 8 Shows Figure 7a and Figure 7b X-ray photo of the blades of the integrated blade disk,

[0064] [ Figure 9a and Figure 9b ] has been described Figure 9a and Figure 9b 1 and 2 show very schematically a side view and a top view of a blade of a one-piece blade disk with a stop according to a fourth test of the prior art,

[0065] [ Fig.10 ] Fig.10 The integrated blade disk with a stopper according to the present invention is schematically shown.

[0066] [ Fig.11a and Fig.11b ] Fig.11a and Fig.11b A perspective view schematically shows a stopper for a trailing edge according to the invention,

[0067] [ Fig.12 ] Fig.12 Schematically shows Fig.11a and Fig.11b A bottom view of the stopper,

[0068] [ Fig.13a and Fig.13b ] Fig.13a and Fig.13b A perspective view schematically showing a stopper for a leading edge according to the invention, and

[0069] [ Fig.14 ] Fig.14 Schematically shows Fig.13a and Fig.13b Side view of the stopper.

[0070] Elements having the same function in different embodiments are provided with the same reference numerals in the figures. DETAILED DESCRIPTION

[0071] Fig.10 An integral blade disk 100 of an aircraft turbine engine is shown, comprising blades 102. An integral blade disk is an integral element of a turbojet engine, part of which is a compressor or a turbine, consisting of a blade and a blade disk 101. An integral blade disk is usually manufactured by machining a uniform metal block. Each blade comprises a blade root (not shown) and a blade 102.

[0072] The blade 102 comprises a pressure side and a suction side connected together by a leading edge 106 and a trailing edge 104. The blade 102 also comprises a free end portion, referred to as a tip portion 108.

[0073] The present invention relates to a method for repair welding a blade 102. The method includes repair welding a tip portion 108 of the blade 102, and also includes fixing a first stopper 110 to a leading edge 106 at the tip portion 108, and fixing a second stopper 112 to a trailing edge 104 at the tip portion 108. In particular, the stoppers 110, 112 are fixed only by pressing the stopper 110 against the leading edge 106 and the stopper 112 against the trailing edge 104.

[0074] Thereafter, the method includes depositing a repair bead on the tip portion 108 from the first stop 110 to the second stop 112. The deposition of the repair bead may be performed by additive manufacturing via powder deposition and fusion.

[0075] Thereafter, the process includes removing the stops 110 , 112 .

[0076] The method may comprise, before fixing the stops 110, 112, preheating the stop 110, in particular by means of a laser. The preheating of the stop 110 enables heating of the stop to avoid the influence of a hot stop and a cold blade.

[0077] exist Fig.10, the dashed box E shows a first stopper 110 pressed to the leading edge 106 at the tip 108; and the box D shows a second stopper 112 pressed to the trailing edge 104 at the tip 108. In this figure and in the box D, the pressure side of each blade 102 of the integrated blade disk 100 is shown, while in the box E, the suction side of the blade 102 is shown.

[0078] The stops 110, 112 may be made of the same material as the repair bead. For example, the stops 110, 112 and the reload bead may be made of titanium filled with 6% aluminum and 4% vanadium (Ti-6Al-4V). Thus, the stops 110, 112 are made of the same metal as the filler metal.

[0079] Each stopper 110 , 112 has a predetermined stiffness (which is adjusted when the stopper is assembled) to apply a force to maintain the stopper pressed against the leading edge 106 or the trailing edge 104 .

[0080] The area of ​​the stops 110 , 112 providing maintenance therefore has sufficient rigidity to provide a spring effect holding the stops on the blade 102 by compression.

[0081] The stops 110, 112 are fixed to the leading edge 106 and the trailing edge 104 with a clearance of 5 / 100 or less. In other words, the stops 110, 112 are configured so that the clearance between the stops and the blade 102 to which the stops are fixed is no greater than 5 / 100.

[0082] Fig.13a , Fig.13b and Fig.14 A stop 110 is shown for securing to the leading edge 106 of the blade 102; Fig.11a , Fig.11b and Fig.12 A stop 112 is shown for securing to the trailing edge 104 of the blade 102 .

[0083] Each stopper 110, 112 comprises a first portion 114 and a second portion 116 arranged opposite each other. The portions 114, 116 are substantially planar and parallel to each other.

[0084] The first portion 114 is configured to be disposed on the pressure side of the blade 102, while the second portion 116 is configured to be disposed on the suction side of the blade 102. Thus, each portion 114, 116 is disposed on opposite sides of the blade 102. The first portion 114 and the second portion 116 are shaped to squeeze the leading edge 106 or the trailing edge 104 of the blade 102.

[0085] Each stopper 110, 112 includes a third portion 118a, 118b connecting the first portion 114 and the second portion 116. The third portion includes a first part 118a of polygonal shape (e.g., substantially parallelepiped shape) connected to a second part 118b of polygonal shape (e.g., substantially parallelepiped shape). The parts 118a, 118b are substantially orthogonal to each other.

[0086] The third portion 118b includes a groove 120 extending substantially parallel to the leading edge 106 or the trailing edge 104 between the first portion 114 and the second portion 116. The groove 120 is configured so that the leading edge 106 or the trailing edge 104 is arranged in the groove. In other words, the leading edge 106 or the trailing edge 104 is arranged in the groove 120 along the groove.

[0087] The groove 120 extends along the leading edge 106 or the trailing edge 104 and extends into a continuation of the tip portion 108 .

[0088] The groove 120 forms an abutment of the leading edge 106 or the trailing edge 104 of the blade 102. In fact, when the stoppers 110, 112 are fixed to the blade 102, the first portion 114 and the second portion 116 are respectively positioned on the pressure side and the suction side of the blade 102, while the groove 120 is positioned continuously with the blade 102 along the leading edge 106 or the trailing edge 104.

[0089] The lengths L1-0 and L1-1 of the stoppers 110 and 112 along the pressure side and the suction side, that is, the lengths of the first portion 114 and the second portion 116 along the pressure side and the suction side, may be greater than or equal to 0.5 mm, in particular greater than or equal to 5 mm. Fig.11b The length L1-1 in can be 7.0 mm, Fig.13b The length L1-0 in can be 6.7mm.

[0090] The length L2-0, L2-2 of the third portion 118b may be greater than or equal to 0.5 mm, in particular greater than or equal to 5 mm. Fig.11b The length L2-2 can be equal to 6.35 mm, and Fig.13b The length L2-0 can be equal to 6.3 mm.

[0091] This length of blade 102 continuing from leading edge 106 or trailing edge 104 ensures proper initiation and termination of the weld bead.

[0092] Thus, the lengths L1 - 0 , L1 - 1 of the first and second portions 114 , 116 along the pressure and suction sides may be substantially equal to the lengths L2 - 0 , L2 - 2 of the third portion 118 b .

[0093] The height H1, H2 of the stoppers 110, 112 and the third portion 118a along the leading edge 106 or the trailing edge 104 may be greater than or equal to 1 mm, in particular greater than or equal to 8 mm. Fig.11a The height H2 of the stopper 112 may be equal to 10 mm. Fig.13a The height H1 of the stopper 110 in the embodiment may be equal to 11 mm. In particular, the height of the stoppers 110, 112 should be sufficient to ensure that the stoppers 110, 112 have a good orientation along the leading edge 106 and the trailing edge 104, respectively. The height difference between the stoppers 110, 112 may be greater than or equal to 0.1 mm.

[0094] The thickness E of the stoppers 110, 112 and thus the distance between the outer wall of the first portion 114 and the outer wall of the second portion 116 may be greater than or equal to 0.2 mm. The thickness E of the stopper 110 may be different from the thickness E of the stopper 112. For example, in Fig.11b In FIG. 13 , the thickness E of the stopper 110 for fixing to the leading edge 106 is 1.5 mm. In FIG. 13 , the thickness E of the stopper 112 for fixing to the trailing edge 104 is 1.15 mm.

[0095] The distance between the inner wall of the first portion 114 and the inner wall of the second portion 116 is substantially equal to the thickness of the blade 102 , ie, the dimension of the blade 102 between the pressure side and the suction side.

[0096] Each stopper 110, 112 includes an undercut 124 extending from the tip 108 and along the leading edge 106 or the trailing edge 104. Thus, the portion of the stopper 110, 112 holding the blade 102 does not contact the melted area of ​​the reload. This avoids the presence of melted material during repair welding.

[0097] The height Hd of the undercut portion 124 may be greater than or equal to 2 mm, in particular, substantially equal to 4 mm.

[0098] The second stop 112 , and more specifically, the third portion 118 of the second stop 112 , may include a second undercut 126 extending along the trailing edge 104 from an end of the third portion 118 a opposite the tip portion 108 .

[0099] The method may further include, before fixing the stoppers 110, 112, tightening the first and second portions 114, 116 of each stopper. Thus, for each blade 102, each stopper 110, 112 is adjusted by tightening the first and second portions to optimize the squeezing effect.

Claims

1. A method for repair welding of an aircraft turbine engine blade (102), the blade (102) comprising a pressure side and a suction side connected by a leading edge (106) and a trailing edge (104), the blade (102) further comprising a free end portion referred to as a tip portion (108), the method comprising repair welding the tip portion (108) and comprising the following steps: - preheating the first stopper (110) by laser, - fixing the first stop (110) to the leading edge (106) at the terminal portion (108) and fixing the second stop (112) to the trailing edge (104) at the terminal portion (108), - depositing a repair bead on the terminal portion (108) from the first stop (110) to the second stop (112), and - removing the first stopper (110) and the second stopper (112), The method is characterized in that the first stopper (110) and the second stopper (112) are fixed only by pressing the first stopper (110) and the second stopper (112) onto the leading edge (106) and the trailing edge (104).

2. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1, wherein: The step of depositing the repair bead is performed by additive manufacturing via powder deposition and melting.

3. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, wherein: The first stopper (110) and the second stopper (112) are made of the same material as the repair weld bead.

4. The method for repair welding of an aircraft turbine engine blade (102) according to claim 3, wherein: The first stopper (110) and the second stopper (112) as well as the repair weld bead are made of titanium loaded with 6% aluminum and 4% vanadium.

5. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, wherein: The first stopper (110) and the second stopper (112) have a predetermined stiffness to apply a force to keep the first stopper (110) and the second stopper (112) pressed against the leading edge (106) and the trailing edge (104).

6. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, wherein: The first stop (110) and the second stop (112) each have an undercut portion (124) extending from the tip portion (108) along the leading edge (106) and the trailing edge (104), respectively.

7. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, wherein: The first stopper (110) and the second stopper (112) are fixed to the leading edge (106) and the trailing edge (104) with a gap of 0.05 mm or less.

8. The method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, wherein: The length of the first stopper (110) and the second stopper (112) along the pressure side and / or the suction side is greater than or equal to 0.5 mm.

9. According to the method for repair welding of an aircraft turbine engine blade (102) according to claim 1 or 2, the first stopper (110) and the second stopper (112) each include a first portion (114) and a second portion (116) arranged relative to each other, the first portion (114) is arranged on the pressure side, and the second portion (116) is arranged on the suction side, and the method further includes the step of tightening the first portion (114) and the second portion (116) of each stopper before the step of fixing the first stopper (110) and the second stopper (112).

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