Blade repairing method of integral blade rotor

Abstract

The invention relates to a method for repairing a turbine blade, in which a damaged region (Di) is machined away (Rz) and repaired using a directed energy deposition process, followed by machining the damaged region to a desired and predetermined aerodynamic profile.

Description

Technical Field

[0001] The present invention relates to an improved blade maintenance advice or method for a gas turbine blade. Specifically, but not exclusively, the method allows for the repair of turbine blades of the type that are increasingly commonly used in high-performance gas turbine aircraft engines. Background Art

[0002] Gas turbine engine blades operate at high speeds and at high temperatures. Although modern manufacturing techniques allow for the use of high-quality materials for precision engineered surfaces, the operating environment of such turbines does mean that over time, damage can occur. This can be due to fatigue, internal damage or inclusions in the material, or even impact damage caused by debris entering the engine and colliding with one or more blades. Therefore, it is necessary to provide a means to repair engines that have suffered such damage or have defective or dangerous blades.

[0003] A common method that allows for the maintenance of engine blades is to form a rotor (an assembly including many blades) with, for example, a plurality of removable blades, each blade extending radially from a central hub disc. If a blade is damaged as described above, this blade can be removed and replaced. This allows for the continued use of such engines through engine blade repair.

[0004] However, there is a desire to reduce the number of components forming the engine, and thus modern engines also use rotors with integral blades, i.e., a single component integrating the central rotor with the radially extending blades. Advantageously, this reduces the number of components, but requires complex single components. Such rotors with integral blades are known in the art as IBRs (Integral Blade Rotors) or alternatively as "Blisks".

[0005] Blisks (Integral Blade Rotors) generally have better aerodynamic performance and efficiency than traditional rotors with separate removable blades, but any damage to an IBR blade requires a significant amount of work to disassemble the engine for maintenance so that the rotor can be replaced. This is a large maintenance task with associated costs, and even though Blisk technology offers increased operating efficiency, it still discourages some operators and manufacturers from using Blisk technology.

[0006] The difficulties in using Blisk technology in rotor manufacturing are further exacerbated by the dimensions of some of the aerodynamic profiles in the aerodynamic profiles forming the blades, particularly in the blade tip regions, where repair is difficult to achieve due to the reduced thickness of the tip geometry.

[0007] The present inventors have devised an alternative repair method and proposal that allows Blisk technology to be more easily used in engine design, thereby allowing engine manufacturers to achieve higher engine efficiency and performance without unduly increasing the repair and maintenance of the blades when the blades are damaged or fatigued and need to be repaired.

[0008] The invention described herein can be applied to gas turbine engine components such as compressor blades or turbine blades and can also be used in power generators that use blade technology, such as generators. Summary of the Invention

[0009] Aspects of the invention are set out in the accompanying claims.

[0010] From a first aspect of the invention described herein, there is provided a method of repairing a fan blade, the fan blade including a repair region and a predetermined repaired geometry, the method comprising the steps of: - Aligning a fan blade repair patch against a pre-machined-away portion defining a repair perimeter of the fan blade, wherein a portion of the perimeter of the fan blade repair patch has a geometry that is substantially complementary in shape to the repair perimeter of the fan blade, thereby defining a joint region located between the fan blade and the repair patch; and - Depositing material into the joint region by direct energy deposition to join the fan blade and the repair patch.

[0011] The fan blade can be a compressor blade for a gas turbine engine or a fan blade for a gas turbine engine. The method described herein can equally be applied to gas turbine guide vanes or blades or fan blades used in turbines for power generation or turbines for nuclear applications such as power generation or propulsion.

[0012] The deposition process itself can be a wire deposition technique or a powder deposition technique. Other deposition techniques can equally be used.

[0013] According to the method described herein, damaged blades can be conveniently repaired and restored to a state in which their aerodynamic performance and structural integrity are restored. The significant cost of replacing damaged blades with brand new blades is appreciable, and thus the method described herein improves the lifespan and operating costs of engines or generators that include damaged blades.

[0014] The damage can be visible or can be identified by appropriate non-destructive testing (NDT) which can identify cracks or fissures compromising the integrity of the blade. Advantageously, the damaged section can be machined off using appropriate machining equipment such as CNC milling equipment etc. Thus, the integrity of the remaining part of the blade can be preserved and only the damaged section or area is machined off. Before the welding process described herein, the surface of the machined-off section can be treated with acid and / or etched.

[0015] The machined-off section or area defines the repair perimeter of the fan blade.

[0016] According to one embodiment described herein, a repair patch for restoring the geometry of the blade is provided. Once the repair patch is welded or joined to the blade to be repaired, a part of the repair patch (along with any excess material) (now attached to the blade) can be machined off to reconstruct the predetermined geometric shape of the turbine blade.

[0017] Advantageously, the size of the repair patch can extend beyond the desired outer dimensions of the repaired blade to achieve the reconstructed geometry. In fact, the repair patch can be deliberately selected to be larger than the desired profile of the blade to allow material to be machined off to achieve the desired final geometry.

[0018] Similarly, the section of the deposited material forming the connection between the repair patch and the blade can be formed to have a geometry that extends beyond the desired final blade profile. First, this allows the process to stabilize before forming the critical repair section. Also, this allows material to be machined off to provide an accurate correspondence between the original blade and the repaired section.

[0019] Advantageously, the step of depositing material by direct energy deposition to join the blade and the repair patch includes the steps of: (a) forming a weld bead to join the blade and the patch together; and (b) repeating the formation of subsequent weld beads to fill the joint area with material.

[0020] The angle between the machined blade to be repaired and the perimeter of the repair patch can be any suitable angle. Advantageously, the joint area can be a generally V-shaped area located between the repair patch and the repair perimeter of the blade. Thus, successive weld beads can be constructed to fill this V-shaped profile. Advantageously, the angle between the machined repair patch and the blade can be between 30 and 50 degrees, more advantageously 45 degrees.

[0021] To avoid any geometric structures that increase stress in the connection between the blade and the repair patch, both the machined blade and the repair patch can be in the form of one or more curves or straight lines and curved profiles. Then, the deposited weld bead material can conveniently conform to the smooth curved profile.

[0022] In another embodiment, the blade repair patch may have a connection area and an area corresponding to the shape of the original blade. Thus, the machining of the repaired blade can be limited to machining only the partition of the connection between the repair patch and the blade, i.e., machining away the excess deposited material.

[0023] As described herein, the repair patch may have a shape such that when adjacent to the machined perimeter of the blade to be repaired, it defines a V-shaped area that can be filled with deposited material.

[0024] Alternatively, the repair patch may take the form of a surface or substrate on which material can be deposited to reconstruct the damaged and removed (machined away) blade section or area. In such an arrangement, the repair patch abuts one side of the turbine blade and defines a substrate section on which material can be deposited. The blade can be machined to include a perimeter at a 45-degree (or other) angle, as described above. In such an embodiment, the repair area is effectively the entire machined-away area, i.e., the deposition step is repeated over the entire substrate to rebuild or reconstruct the material on the substrate.

[0025] To form a uniform and consistent deposition (weld) bead, advantageously, the deposition step can start or initiate from a location outside the geometry of the desired repaired blade. By starting the deposition at start and stop positions outside the geometry of the desired blade, the integrity of the deposited material can be maintained and any discontinuities associated with the start and stop of the deposition of the material or laser heating can be avoided. Thus, in such an arrangement, when the repair patch abuts the repair perimeter of the blade, at least one of the dimensions of the patch extends beyond the dimensions of the desired repaired geometry of the blade.

[0026] In another arrangement, all of the dimensions of the repair patch in the x, y, and z planes can extend beyond the dimensions of the desired repaired geometry of the blade, and the method can include the step of machining those dimensions of the joined blade and patch to reconstruct the predetermined blade geometry. Advantageously, each deposition step can then start and stop on that portion of the repair patch that is outside the dimensions of the predetermined repaired geometry.

[0027] The repair methods described herein can be used with a variety of deposition additive manufacturing processes, including, but not limited to, laser blown material deposition or laser wire deposition.

[0028] Additionally or alternatively, a method can include the step of machining and acid etching the edges of the repair patch to be welded. This avoids the formation of undesired alpha-phase material.

[0029] Advantageously, the methods described herein may additionally include heat treating the processed and repaired blade. This may be a local heat treatment of the repaired section of the blade or a heat treatment of the entire blade by means of an oven or autoclave.

[0030] The methods described herein may also include one or more steps of cooling all or part of the repair patch during the material deposition step. By doing so, a fine microstructure of the material with improved metallurgical and mechanical properties can be achieved.

[0031] From another aspect, there is provided a method for powder blown laser metal deposition or laser wire metal deposition blade repair, the blade including a repair area and a predetermined repaired geometry, the method including the steps of: - machining away a portion of the turbine blade that includes the repair area, wherein the machined portion defines a repair perimeter of the blade; - aligning a blade repair patch against or adjacent to the machined away portion, wherein a portion of the perimeter of the blade repair patch has a geometry that is substantially complementary in shape to the repair perimeter of the blade, thereby defining a bonding zone between the blade and the repair patch; and - performing powder blown or wire laser metal deposition within the bonding zone to bond the turbine blade and the repair patch.

[0032] From yet another aspect, there is provided a method for fan blade repair, the fan blade including a repair area and a predetermined repaired geometry, the method including the steps of: - aligning a fan blade repair patch against a pre-machined away portion of the fan blade that defines a repair perimeter, wherein a portion of the perimeter of the fan blade repair patch has a geometry that is substantially complementary in shape to a portion of the external geometry of the fan blade, thereby defining a substrate zone for receiving deposited material; and - depositing material into the substrate zone by direct energy deposition to bond the fan blade and the repair patch and rebuild a volume of material to form a repaired blade.

[0033] From yet another aspect, there is provided a computer numerical control robotic arm that includes a deposition device configured to perform a method according to the methods described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Now, various aspects of the invention will be described by way of example only in conjunction with the drawings, in which:

[0035] Figure 1 A to 1J illustrate the steps of a first embodiment of the method described herein;

[0036] Figure 1 K shows a cross-sectional view of a repaired blade according to the method described herein;

[0037] Figure 2 A through 2D show repair patches according to the method described herein;

[0038] Figures 3A to 3D Shows a repair patch and a cross-section through the repair patch, and also shows the weld bead formed between the blade and the patch;

[0039] Figure 4 A through 4D show the repaired blade with the repair patch before machining;

[0040] Figure 5 A through 5I show alternative repair methods described herein;

[0041] Figure 5 J shows a cross-sectional view of a repaired blade according to the method described herein;

[0042] Figure 6 A through 6D and 6A' through 6D' show a second method, and plan and cross-sectional views of the base patch before and after deposition.

[0043] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail herein. However, it should be understood that the appended drawings and detailed description are not intended to limit the invention to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the claimed invention.

[0044] Any reference in this specification to prior art documents should not be construed as an admission that such prior art is well known or forms part of the common general knowledge in the art. The words "comprising", "including" and similar words used in this specification should not be construed as having an exclusive or exhaustive meaning. In other words, they are intended to mean "including but not limited to". The invention is further described by reference to the following examples. It should be understood that the claimed invention is not intended to be limited in any way by these examples. It will also be recognized that the invention covers not only individual embodiments but also combinations of the embodiments described herein.

[0045] The various embodiments described herein are only for helping to understand and teach the claimed features. These embodiments are provided only as representative samples of the embodiments and are not exhaustive and / or exclusive. It should be understood that the advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein should not be considered as limitations on the scope of the invention defined by the claims or on equivalents of the claims, and other embodiments can be utilized and modified without departing from the spirit and scope of the claimed invention. Appropriately, and in addition to those specifically described herein, the various embodiments of the invention can include, consist of, or consist essentially of a suitable combination of the disclosed elements, components, features, parts, steps, means, etc. Further, the present disclosure can include other inventions that are not currently claimed but may be claimed in the future.

[0046] It should be recognized that the features of the various aspects of the invention described herein can be conveniently and interchangeably used in any suitable combination. Detailed Description

[0047] Figure 1 A through 1K illustrate the steps of a first embodiment of a method for repairing a turbine blade described herein. The blade shown has a simplified geometry, but it should be understood that a turbine blade has a complex curved and aerodynamic profile / shape not shown in this figure.

[0048] Figure 1 The blade 1 in A contains a discontinuity D i (i.e., damage) that needs to be repaired in order to safely use the blade and maintain its aerodynamic characteristics and performance. It will be recognized that Figure 1 the blade 1 shown in A is one of a plurality of blades that extend radially from a central hub disk.

[0049] The discontinuity D i can be caused by fatigue, erosion, impact damage, or as a result of other operating conditions or events. As described above, in a conventional arrangement with removable blades, this single blade would be removed and replaced. In an integral blade arrangement, it would typically be necessary to replace the entire rotor, i.e., including blades that are not actually damaged.

[0050] Figure 1 B shows a repair zone or area Rz, which represents an area of the blade that is greater than the discontinuity D i or the damaged section. The first step of the repair method described herein involves machining away the repair zone / portion of the blade, i.e., machining away a portion of the blade that is large enough in area to remove the discontinuity D i or the damaged section.

[0051] Any suitable machining operation, such as, for example, a robotic milling machine, can be used to machine away the repair zone / section. As shown, the repair zone / section is machined to not only remove the discontinuity D i , but also to define a smooth curved portion that facilitates the removal of any stress-inducing geometries in the repair. As shown, a radius is provided, as Figure 1 shown at B.

[0052] Figure 1 C also shows additional features of the repair zone Rz, and specifically, a tapered geometry to the edge of the zone. This tapered geometry mates with the geometry of the repair patch (described below) to define a region in which repair material can be deposited and which allows for a strong and reliable connection between the repair patch and the blade.

[0053] The angle of the taper can be any suitable angle. However, an angle of 45 degrees allows for convenient welding access while minimizing the welding material required to attach the patch to the blade or to reconstruct the blade surface on the backing plate.

[0054] Advantageously, the invention described herein includes a repair system that includes a plurality of repair patches, each patch having a different size and being usable to repair different sized damages. For example, a deep and narrow crack or damaged portion of a blade may require a long and narrow repair patch. Conversely, a blade damage confined to the blade surface may require a longer but less deep repair patch. Thus, a suitable patch size can be selected for the repair, and the corresponding area of the blade can be machined away to remove the damage.

[0055] Figure 1 D shows a repair patch according to one embodiment of the repair method described herein. The repair patch 2 is shown in more detail in Figure 2 A through 2D, in which the repair patch 2 abuts the blade 1. As shown, the repair zone / section has been machined and includes the curved geometry described above.

[0056] As shown, the repair patch 2 includes a first region 3 that can correspond to the desired geometry of the repaired blade. Alternatively, it can have a geometry that allows the reconstructed geometry of the repaired blade to be created by machining the region 3, i.e., the dimensions of the region are larger than the desired geometry to allow the region to be machined down to the desired geometry.

[0057] As shown, the repair patch 2 has two optional abutment stops 4A and 4B that abut the edge of the blade to allow the patch to be in close contact with the blade before the patch and the blade are joined together to create the repaired blade. Figure 3BShows an end view of the edge of the repair patch adjacent to the blade (see Figure 2 X1 in D). As shown, the deposition area 5 is provided in a generally V-shaped profile between the repair patch 2 and the blade 1. The wedge-shaped abutments 4A and 4B allow the patch to be firmly positioned against the blade during the deposition process (described below).

[0058] Figure 2 A, 2B, and 2C show side and plan views of the repair patch and the blade before material deposition has occurred in area 5. It should be appreciated that the abutments 4A and 4B firmly position the repair patch in the exact desired location.

[0059] Figure 3A Shows the repair patch and the blade before welding. Figure 3B Shows through Figure 3A the cross-sectional view of the A-A' section in Figure 3C and 3D Shows an example of how the weld bead is established between the blade and the patch.

[0060] As Figure 2 A to 2D and Figure 3B also shown, the geometry of the repair patch extends beyond the original geometry of the blade 1 in the x, y, and z directions. These are shown by the dimensions Δx, Δy, and Δz.

[0061] The extended geometry Δx, Δy, and Δz is important in the repair process because they allow the repair patch to provide a material deposition area 5 that starts and ends outside the boundaries of the normal geometry of the blade. Specifically, since the geometry Δx, Δy, and Δz is greater than the desired geometry of the blade after repair (i.e., the aerodynamic outer contour), several technical advantages can be achieved according to the method described herein:

[0062] First, the excess material allows for machining to restore the original blade geometry. The excess material provided by the patch allows for the formation of precise geometries.

[0063] Second, by providing an "oversized" repair patch whose geometry extends beyond the blade in the x and y axes, a deposition path or deposition area 5 is provided that can start and end outside the normal boundaries or edges of the blade. This provides a continuity advantage, which is further described later.

[0064] During the welding process, appropriately, the repair patch can be clamped to the surrounding blade to ensure the continuity of the weld, the repair patch, and the blade.

[0065] In addition, the upper surface 6 of the repair patch (as Figure 3BAs shown in [figure reference], it may already conform to the desired geometry of the repaired blade, thereby reducing the required machining to only the other geometries of the blade.

[0066] Figure 3C Illustrates how to use overlapping bead welds as shown to reconstruct or "fill" area 5. After welding, the excess of the convex bead extending from surface 6 can be machined off to achieve the desired profile.

[0067] Figure 4 Figure D shows an alternative repair where a thinner base layer is used and bead welds can be laid down step by step on this base layer. In this example, the patch may be redundant and the entire replacement is created using bead welds. Again, the excess material (including the base) can be machined off to achieve the desired profile.

[0068] The invention described herein has particularly advantageous applications in aircraft engine design and operation not only in fixed-wing aircraft but also in rotary-wing aircraft such as helicopters.

[0069] Now reference will be made to Figure 1 Figures A to 1H to describe the deposition steps.

[0070] As described above, the repair patch contacts blade 1, for example as Figure 1 shown in Figure E. Next, a first deposition step is carried out in which a first connecting bead weld 7 is deposited at the bottom of the generally V-shaped area 5 as Figure 1 shown in Figure F. This connecting bead weld joins the patch and the blade together.

[0071] The deposition process involves blowing powder towards a laser beam which melts the powder and forms a molten pool. The laser beam and the powder move simultaneously to create a bead weld which cools as the laser moves along the bead weld. Advantageously, the process described herein provides a repair process that involves less heat generation in the blade and the repair material. Specifically, the powder is fed into the molten pool created by the laser in the base material. The powder is melted by the laser and by entering into the molten base material. Most of the cooling comes from conduction from the surrounding unmolten base material and previously deposited material. However, some cooling comes from the surrounding gas environment (convection) and some cooling is radiated away. This advantageously reduces the impact of high temperatures on the blade.

[0072] Conventional robot-controlled laser beam welding machines can be used and will be understood by those skilled in the field of additive manufacturing. A typical and suitable laser source is the TruDisk 5001 manufactured by Trumpf GmbH.

[0073] Importantly, as shown, the deposited bead welds start outside the geometry of the blade, i.e., in Figure 1 Figure F,Figure 2 and Figure 4 within the △x region and △y region shown in. Advantageously, this means that when the material is deposited to form the repair blade partition, as the deposition process begins, the temperature and material flow / melting are in a smooth and stable state.

[0074] By avoiding starting and stopping the deposition within the repair portion or partition, discontinuities and deposition inclusions can be avoided, thereby creating a high-quality deposited material within the repair zone or portion.

[0075] This start and stop position also allows for precise control of the deposition bead with respect to its position relative to each other in each dimension.

[0076] Referring Figure 1 to FIGS. 1G and 1H, the next stage of the method involves further deposition occurring, as shown by further deposition bead 8.

[0077] Now referring Figure 1 to FIGS. 1I and 1J, the process is repeated until the deposition area 5 has been completely filled with material. As Figure 1 shown in FIG. 1J, the deposition bead continues to extend beyond the upper surface of the desired blade geometry. The resulting blade (after the deposition step) has a repair zone whose geometry exceeds the desired final blade aerodynamic profile. In fact, the desired and predetermined aerodynamic shape of the repaired blade is contained within the volume of material formed by the deposition process. Importantly, due to the way the deposition starts and terminates outside of those desired geometries, the quality, uniformity, and thus reliability of the resulting repaired component (here the blade) can be optimized.

[0078] The final blade geometry can be created by machining away the excess material deposited around the predetermined and desired geometry of the repaired blade. This can be done by any suitable milling or machining operation, but advantageously can also be performed by a multi-axis robotic head to allow for the creation of complex geometries between adjacent blades (other blades not shown). The machined away geometry and cross-section are shown in Figure 1 FIG. 1K.

[0079] Figure 4 FIGS. 4A to 4D show the weld or deposition joint between the repair patch and the blade.

[0080] Figure 1K shows a view of the machined blade, including a cross - section of the joint between the repair patch and the blade after machining has occurred. As shown, the connection between the repair patch and the blade is a generally V - shaped joint formed by a deposited material that follows the curved deposition path described above. Also shown is that excess deposited material in the deposition process has been machined away, as has the backing portion of the repair patch and the adjacent stop. Thus, the resulting blade with the desired and original aerodynamic performance can be reconstructed.

[0081] Figure 5 A through 5J show alternative repair methods according to the invention described herein.

[0082] As Figure 5 shown in A, the blade 1 contains a discontinuity Di or damaged portion that needs repair. As in the example above, the repair zone Rz is determined and machined away using conventional machining techniques. Also, the repair zone Rz contains a generally curved profile and a tapered shape to create a welding or deposition zone 5 (see Figure 3). In this example, the repair patch is in the form of a substrate 8, optionally, the profile of which on one side corresponds to the desired aerodynamic profile on a given side of the blade. Optionally, the substrate may contain the adjacent stops described above, although they are not shown in Figure 5 it.

[0083] The repair method includes the steps of: contacting the substrate repair patch 8 with the blade to be repaired and then depositing material on the substrate in a shape complementary to the repair zone. As in the above example, the geometry of the substrate extends beyond the geometry of the predetermined repaired blade so that the deposition can start and end outside of these geometries. The above advantages also apply to this example.

[0084] Referring Figure 5 to E, 5F, 5G, and 5H, successive depositions are made to build up the desired material on the substrate, which also extends beyond the geometry of the blade's predetermined desired shape. Figure 5 I shows the resulting component, where the deposited material extends beyond the desired geometry of the blade.

[0085] The final step is as Figure 5 shown in J, in which the excess material has been machined away to create the desired and predetermined blade shape.

[0086] Figure 6 A through 6D and 6A' through 6D' show a second method and plan and cross - sectional views of the substrate patch before and after deposition.

[0087] Optionally, the blade can be heat treated to remove residual stresses caused by the welding process. Advantageously, heating and cooling the blade or repair patch after welding allows control of the temperature history of the component and restores it to the original characteristics of the blade.

[0088] Advantageously, during the welding process, cooling can be carried out by applying a coolant or cooling device to the repair patch or plate at the time of welding. Cooling the repair patch or plate during deposition causes the weld to cool down faster and this creates a fine microstructure in the weld. More specifically, it allows replication of the original microstructure of the blade (e.g., it can be forged), which enhances the mechanical integrity of the blade and the restoration of blade performance.

[0089] Alternatively, heat treatment can be applied and the component can be allowed to cool under ambient conditions.

[0090] In addition to the above advantages regarding the continuity and quality of the deposited material, the arrangements and methods described herein provide further advantages.

[0091] As described herein, the blade can be repaired with a sacrificial or partially integrated repair patch. The term "partially integrated" is in contrast to a fully deposited repair and is intended to mean that the repair patch has at least some aspects of the pre - desired geometry of the blade and / or some of the material that forms part of the repaired blade.

[0092] Advantageously, using the patch described herein conducts the energy from the laser beam away from the blade being repaired. This means that thermal damage that might be caused by the repair process can be avoided. The heat - affected zone can be significantly reduced and the residual stresses can be significantly lowered.

[0093] Advantageously, the welding can be carried out in an oxygen - free environment. For example, an argon gas flow or argon gas shroud can be formed around the weld to prevent the formation of alpha - phase material within or on the weld. Interaction with oxygen during the welding process undesirably produces alpha - phase material, which can cause cracking of the titanium material.

[0094] The weld bead itself can be of any suitable size. However, advantageously, a weld bead with a width (W) between 0.1 - 10 mm and a height (h) between 0.1 - 10 mm provides good welding integrity while allowing an economical rate of blade repair. Small weld beads also minimize the possibility of unwanted weld porosity.

[0095] The inventors have determined that, according to the invention described herein, both laser powder deposition welding and also laser wire deposition can be used. These two additive manufacturing techniques and the operation of these machines will be understood by those skilled in the art of additive manufacturing.

Claims

1. A method for repairing a fan blade, the fan blade including a repair area and a predetermined repaired geometric structure, the method comprising the following steps: - Align a fan blade repair patch against a pre-machined away portion defining a repair perimeter of the fan blade, wherein a portion of the perimeter of the fan blade repair patch has a geometric structure that is substantially complementary in shape to the repair perimeter of the fan blade, thereby defining a bonding zone located between the fan blade and the repair patch; And - Deposit material into the bonding zone by direct energy deposition to bond the fan blade and the repair patch together.

2. The method according to claim 1, further comprising the following steps: Machine away a portion of the turbine blade repair patch and excess material to reconstruct the predetermined geometric structure shape of the turbine blade.

3. The method according to claim 1 or 2, wherein the step of depositing material by direct energy deposition to join the turbine blade and the repair patch comprises the following steps: (a) Form a bead to bond the blade and the patch together; And (b) repeatedly form subsequent beads to fill the bonding zone with material.

4. The method according to any one of the preceding claims, wherein the bonding zone is in the form of a substantially V-shaped area located between the repair patch and the repair perimeter of the blade.

5. The method according to any one of the preceding claims, wherein the repair perimeter of the blade includes at least one radius of curvature.

6. The method according to any one of the preceding claims, wherein the turbine blade repair patch has a connection area and an area corresponding in shape to the original blade.

7. The method according to any one of the preceding claims, wherein the turbine blade repair patch abuts one side of the turbine blade and defines a substrate partition, and the material can be deposited onto the substrate partition.

8. The method according to any one of the preceding claims, wherein when the turbine repair patch abuts the repair perimeter of the turbine blade, at least one of the dimensions of the patch extends beyond the dimensions of the desired repaired geometric structure of the blade.

9. The method according to claim 8, wherein all dimensions of the patch in the x, y, and z planes extend beyond the dimensions of the predetermined repaired geometric structure of the blade, and the method includes the step of machining those dimensions of the bonded blade and patch to reconstruct the predetermined blade geometry.

10. The method according to claim 8 or 9, wherein each deposition step starts and ends on a portion of the repair patch that is outside the dimensions of the predetermined repaired geometric structure.

11. The method according to any one of the preceding claims, wherein the step of direct energy deposition is an additive manufacturing process of laser blown material technology or laser wire deposition.

12. The method according to any one of the preceding claims, further comprising the step of machining, and optionally acid etching, the edges of the repair patch to be welded.

13. The method according to any one of the preceding claims, further comprising: Machine away a portion of the fan blade that includes the repair area, wherein the machined portion defines the repair perimeter of the fan blade.

14. The method according to any one of the preceding claims, further comprising the step of heat treating the machined and repaired blade.

15. The method according to any one of the preceding claims, further comprising the step of cooling all or part of the repair patch during the step of depositing the material.

16. A method for repairing a turbine blade by powder blowing laser metal deposition or wire laser metal deposition, the turbine blade comprising a repair region and a predetermined repaired geometry, the method comprising the steps of: - machining away a portion of the turbine blade, the portion comprising the repair region, wherein the machined portion defines a repair perimeter of the turbine blade; - aligning a turbine blade repair patch against the machined-away portion, wherein a portion of the perimeter of the turbine blade repair patch has a geometry that is substantially complementary in shape to the shape of the repair perimeter of the turbine blade, thereby defining a bonding zone between the turbine blade and the repair patch; and - performing powder blowing or wire laser metal deposition within the bonding zone to bond the turbine blade and the repair patch.

17. A method for repairing a fan blade, the fan blade comprising a repair region and a predetermined repaired geometry, the method comprising the steps of: - aligning a fan blade repair patch against a pre-machined-away portion of the fan blade that defines a repair perimeter, wherein a portion of the perimeter of the fan blade repair patch has a geometry that is substantially complementary in shape to a portion of the external geometry of the fan blade to define a substrate region for receiving a deposited material; and - depositing a material into the substrate region by direct energy deposition to bond the fan blade and the repair patch and to reconstruct a volume of material to form the repaired blade.

18. A fan blade repaired by the method according to any one of the preceding claims.

19. A computer numerical control robotic arm comprising a laser metal deposition device configured to perform the method according to any one of the preceding claims.

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