TECHNICAL FIELD

[0001] The present disclosure is directed, in general, to hybrid manufacturing of components and more specifically to hybrid manufacturing including additive manufacturing of metallic components.

BACKGROUND

[0002] The manufacture and/or repair of certain components can be challenging due to different operating conditions and failure modes on different portions of the component. Gas turbine blades are an example of such a component where different areas of the blade can fail for different reasons. Manufacturing such a component using conventional manufacturing techniques can result in compromises in some of these areas and increased potential for damage.

SUMMARY

[0003] A repaired gas turbine blade includes a blade root, a platform coupled to the root, an airfoil portion that extends from the platform and includes a leading edge that extends from the platform, and a damaged portion, and a replacement piece manufactured separately from the airfoil portion and fixedly attached to the airfoil to replace the damaged portion.

[0004] In another construction, a method of repairing a gas turbine blade includes removing a damaged portion of the gas turbine blade and manufacturing a replacement piece for the damaged portion of the gas turbine blade. At least a portion of the replacement piece is additive ly manufactured using an additive manufacturing process. The method also includes attaching the replacement piece to the gas turbine blade.

[0005] In another construction, a repaired gas turbine blade includes a blade root, a platform coupled to the root, and a first airfoil portion formed as one piece with the platform, the first airfoil portion extending from the platform to an intermediate point. A second airfoil portion is formed separate from the first airfoil portion. The second airfoil portion includes a blade tip. An attachment mechanism is positioned between the first airfoil portion and the second airfoil portion to fixedly attach the first airfoil portion and the second airfoil portion to define a complete airfoil that extends from the platform to the blade tip.

[0006] The foregoing has outlined rather broadly the technical features of the present disclosure so that those skilled in the art may better understand the detailed description that follows.

Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiments disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure in its broadest form.

[0007] Also, before undertaking the Detailed Description below, it should be understood that various definitions for certain words and phrases are provided throughout this specification and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases. While some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a perspective view of a turbine blade including a root and a vane portion.

[0009] Fig. 2 is an enlarged perspective view of a vane portion of a gas turbine blade.

[0010] Fig. 3 is a perspective view of a first replacement piece suitable for use in a leading edge portion of the vane portion.

[0011] Fig. 4 is a perspective view of a second replacement piece suitable for use in replacing a full cross-sectional piece of the vane portion. [0012] Fig. 5 is a side view of a vane portion including a replacement piece.

[0013] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

[0014] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout.

The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0015] Also, it should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms“including,” “having,” and“comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms“a”,“an” and“the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term“and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term“or” is inclusive, meaning and/or, unless the context clearly indicates otherwise. The phrases“associated with” and“associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like.

[0016] Also, although the terms "first", "second", "third" and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0017] In addition, the term "adjacent to" may mean: that an element is relatively near to but not in contact with a further element; or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase“based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

[0018] Fig. 1 illustrates a basic turbine blade 10 of the type used in gas turbines or steam turbines for power generation. The blade 10 of Fig. 1 is greatly simplified but includes a root 15, a platform 20, and a vane portion 25. In most constructions, the root 15, the platform 20, and the vane portion 25 are formed as one continuous piece from one material using common forming methods (e.g., forging, machining, casting, etc.).

[0019] The blade root 15 is formed to attach to a rotor or disk if it is a rotating blade or to a blade ring or casing for stationary blades. Each application of the blade 10 has different operating conditions and therefore may include differently-shaped or sized roots 15 as may be required.

[0020] The vane portion 25 is an airfoil-shaped portion that interacts with the fluid flowing through the turbine to expand the fluid and produce rotation of the rotor. The vane portion 25 includes a leading edge 30, a trailing edge 35, a pressure side 40, and a suction side 45. The vane portion 25 extends along a length 50 from the platform 20 which acts as an interface between the root 15 and the vane portion 25 to a blade tip 55.

[0021] Turbine blades and gas turbine blades 10 in particular, are exposed to operating environments that can cause damage to the leading edge 30 as well as to the blade tip 55. The high temperature gas that flows past the vane portion 25 can cause damage as can foreign object impacts that may occur from time to time. Additionally, the blade tip 55 can contact stationary components during operation creating friction, localized heating, and in some cases damage.

Figs. 1 and 2 illustrate a potential leading edge damage region 60 and a blade tip damage region 65, with Fig. 2 being a more detailed illustration of the vane portion 25 of a gas turbine blade 10. Of course, other damage locations are possible and could be repaired using the techniques described herein.

[0022] Fig. 3 illustrates a first replacement piece 70 that is well-suited as a replacement piece for the leading edge damage region 60 of the vane portion 25 of Fig. 2, and Fig. 4 illustrates a second replacement piece 105 that will be discussed with regard to Fig. 4. The first replacement piece 70 includes a leading edge 30a, a portion of a pressure side 40a, and a portion of a suction side 45a that extend along a first length 75. In the illustrated construction, an internal wall 80 extends between the pressure side 40a and the suction side 45a and cooperates with the leading edge 30a to define a first hollow space 85. The space 85 can be used for cooling air flow during operation as may be required by the particular blade 10. The interior wall 80 also cooperates with the pressure side 40a and the suction side 45a to at least partially define a second hollow space 90 that could be used for coolant flow as well. In other constructions, one or both of the spaces 85, 90 are substantially solid as may be required by the particular design. The pressure side 40a and suction side 45a walls include tapered ends 95 to facilitate the attachment of the first replacement piece 70 to the vane portion 25 as will be discussed in greater detail. In some constructions, holes 100 are formed (e.g., drilled, laser cut, formed during manufacture, etc.) in the leading edge 30a to facilitate the flow of cooling gas therethrough. In some cases, the number of holes 100 in the first replacement piece 70 or the second replacement piece 105 are increased or decreased, or the size or position of the holes 100 are changed, when compared to the original design to change the air flow and improve the operation of the blade 10.

[0023] The first replacement piece 70 is well-suited to manufacture using an additive manufacturing process such as direct metal laser sintering (DMLS) or selective laser sintering (SLS). For each of these processes, as well as other suitable processes, the first replacement piece 70 is manufactured or built-up in a layer by layer fashion. Additive manufacturing allows for the production of unique first replacement pieces 70 for each blade repair. This is necessary as each repair may require shorter or longer first lengths 75 for the first replacement piece 70 or a larger or smaller suction side 45a or pressure side 40a wall. If holes 100 are required in the first replacement piece 70, they can be simultaneously manufactured into the piece 70 as it is built or they can be drilled or otherwise formed after the first replacement piece 70 is manufactured.

[0024] In addition, the additive manufacturing processes allow for the use of materials that might otherwise be difficult to form into the first replacement piece 70 or the second replacement piece 105. The use of additive manufacturing processes to manufacture the first replacement piece 70 allows for the use of materials that are best suited to the operating environment of the turbine blade 10 or even the specific location of the replacement piece 70. For example, oxide dispersion strengthened (ODS) or advanced single crystal materials (CMSX8, Rene N5, etc.) that have better strength oxidation resistance and coating adhesion than prior materials can be used to form the first replacement piece 70 or the second replacement piece 105, regardless of the original blade materials.

[0025] Fig. 4 illustrates the second replacement piece 105 that is arranged to replace a second length 110 of a full cross-sectional portion of the vane portion 25 of the blade 10. In situations where the blade tip 55 is damaged, the entire cross-section of the vane 25 from an intermediate point 115 below the damaged region to the blade tip 55 is removed. The second replacement piece 105 is manufactured using additive manufacturing processes to replace the removed portion. As with the first replacement piece 70, processes such as direct metal laser sintering (DMLS) or selective laser sintering (SLS) are well-suited to the manufacture of the second replacement piece 105. In most gas turbine blades 10, the cross-section of the vane 25 will include internal walls 80 (shown in Fig. 3) that cooperate with the outer walls of the vane 25 (i.e., the leading edge 30, the trailing edge 35, the pressure side 40, and the suction side 45) to define interior spaces 85, 90 or chambers that provide for the flow of coolant such as cooling air. Holes 100 are either formed in the second replacement piece 105 as it is manufactured or are drilled or otherwise formed to provide for coolant flow out of the vane portion 25. A complete cover 120 is formed near the top of the second replacement piece 105 to enclose the interior of the vane portion 25 to force air to move through the vane 25 and the various apertures 100 as desired. [0026] Again, the use of additive manufacturing processes to manufacture the second replacement piece 105 allows for the use of materials that are best suited to the operating environment of the turbine blade 10 or more specifically the region in which the replacement piece 70, 105 is located. For example, oxide dispersion strengthened (ODS) or advanced single crystal materials (CMSX8, Rene N5, etc.) that have better strength oxidation resistance and coating adhesion than prior materials can be used.

[0027] In most repairs, the first length 75 and the second length 110 are at least five percent of the blade length 50 which is typically measured along the leading edge 30. Of course longer or shorter replacement pieces 70, 105 could be manufactured using the techniques described herein.

[0028] As illustrated in Fig. 5, an attachment mechanism 125 is positioned between the vane portion 25 and the first replacement piece 70 or the second replacement piece 105 to facilitate permanent attachment to the vane 25. In one construction, brazing material is used as the attachment mechanism 125 to facilitate brazing the first replacement piece 70 or the second replacement piece 105 to the vane 25. As used herein,“permanent” means that the replacement piece 70, 105 cannot be removed without damaging or destroying the blade 10 and that the replacement piece 70, 105 is effectively part of the blade 10 as if it had been manufactured as a single piece.

[0029] In order to repair the turbine blade 10, the damaged portions 60, 65 must first be identified and then removed from the blade 10. Removal can be performed using a number of processes, including but not limited to cutting, grinding or machining. Once removed, the space created can be measured in order to manufacture the replacement piece 70, 105. In the case of a leading edge repair, the length of the gap 75 as well as the length of the pressure side and suction side portions must be measured. In addition, any internal structure and holes should be identified. For a blade tip repair, the length of the removed portion 110 is required as well as the cross-section of the portion, any internal structure, and any hole locations and sizes.

[0030] The information regarding the removed portions 60, 65 is used to aid in the manufacture of the replacement pieces 70, 105 as may be required for each damaged blade 10. Additive manufacture allows for the manufacture of“one off’ components such as the first replacement piece 70 and the second replacement piece 105. Once completed, any holes 100 or other structure not formed during the additive manufacturing process are added to the first replacement piece 70 and the second replacement piece 105.

[0031] Braze material 125 is positioned at the joint between the vane portion 25 and the first replacement piece 70 and/or the second replacement piece 105. The vane 25 and first replacement piece 70 and/or the second replacement piece 105 are then heated to melt the braze material and complete the attachment of the first replacement piece 70 and/or the second replacement piece 105 to the vane portion 25. If required, post-attachment steps such as machining, polishing, coating application, etc. can be performed to complete the repair.

[0032] While SLS and DMLS are discussed in greater detail, other additive manufacturing processes are also suitable for use in manufacturing the replacement pieces 70, 105. Thus, the phrase“additive manufacturing process” should be interpreted broadly to include any of the processes discussed herein as well as other processes not discussed herein. For example, laser metal deposition (LMD) or Electron beam melting (EBM) could also be employed as could many other additive manufacturing processes.

[0033] In general, additive manufacturing delivers feedstock in one of three ways and the suitable processes can be classified by the way this feedstock is delivered. SLS and DMLS are examples in which feedstock is provided in a Powder Bed. Selective Laser Melting (SLM) and Electron Beam Melting (EBM) are other examples of suitable powdered bed processes. A second feedstock delivery system is sometimes referred to as a powder- fed system. Powder-fed systems include Laser Engineering Net Shape (LENS), Laser Metal Deposition-powder (LMD- p), etc. In these systems feedstock is blown through a nozzle to a location where the powder is melted. A third feedstock delivery system is a wire feed system. In these systems wire is fed through a nozzle and melted at a desired location. Examples of wire feed systems include Laser Metal Deposition-wire (LMD-w) and Electron Beam Additive Manufacturing (EBAM).

[0034] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form. [0035] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims.

Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.