Patent Application
20170198584
The present disclosure relates generally to rotary machines and, more specifically, to systems and methods for repairing a component of a rotary machine.
At least some known rotary machines, such as gas turbines, include components, such as, but not limited to, turbine nozzles, rotor blade airfoils, and/or shrouds, that may be exposed to mechanical stresses during operation. At least some of such components may incur damage, for example, a crack may form within the substrate when subjected to tension loading thus reducing the service life of the components. Repair of some such components requires removing the damaged area from the substrate via machining. The removed area is replaced by an insert or coupon that is welded into the cavity created by the removal of the damaged area. In at least some components, the weld between the insert and the substrate may carry the entire tension loading on the component while the rotary machine is in operation, thereby relying on a high quality of the weld for the insert to function. However, at least some components are formed from a substrate material, such as a high gamma prime superalloy, for which it is difficult to achieve a high-quality weld. Additionally or alternatively, at least some known repair methods require brazing the replacement insert onto the component substrate. However, at least some brazes do not perform well under tension loading.
In one aspect, a component is provided. The component includes a substrate configured to receive tensile stress in a first direction. The substrate includes a recess defined therein on a surface of the substrate. The recess includes a first portion having a first width defined in a second direction extending substantially transverse to the first direction along the surface. The recess also includes a second portion having a second width defined substantially parallel to the second direction, and a third portion between the first and second portions along the first direction. The third portion having a third width defined substantially parallel to the second direction such that each of the first width and the second width is different than the third width. The component further includes an insert coupled to the substrate. A perimeter of the insert is sized substantially identically to a perimeter of the recess such that the insert is received within the recess in a clearance fit.
In another aspect, a rotary machine is provided. The rotary machine includes a component configured to receive tensile stress when the rotary machine is in operation. The component includes a substrate and a recess defined therein on a surface of the substrate. The recess includes a first portion having a first width defined substantially transverse tensile stress along the substrate and a second portion having a second width defined substantially transverse to tensile stress along the substrate. The recess further includes a third portion between the first and second portions along the tensile stress direction. The third portion having a third width defined substantially transverse to tensile stress along the substrate such that each of the first width and the second width is different than the third width. The component further includes an insert coupled to the substrate. A perimeter of the insert is sized substantially identical to a perimeter of the recess such that the insert is received within the recess in a clearance fit.
In another aspect, a method for repairing a component is provided. The method includes removing a damaged area from a substrate of the component such that a recess is created in a surface of the substrate. The substrate is configured to receive tensile stress in a first direction. The recess includes a first portion having a first width defined in a second direction extending substantially transverse to the first direction along the surface. The recess also includes a second portion having a second width defined substantially parallel to the second direction and a third portion between the first and second portions and having a third width defined substantially parallel to the second direction such that each of the first and second widths are different than the third width. The method further includes coupling an insert to the substrate. A perimeter of the insert is sized substantially identically to a perimeter of the recess such that the insert is received within the recess in a clearance fit.
The exemplary repair inserts and methods described herein overcome at least some of the disadvantages associated with known repair inserts and methods for repairing a rotary machine component. The exemplary components described herein include a recess defined on a surface of a substrate that receives tensile stresses and an insert coupled to the substrate such that the insert is received within the recess in a clearance fit. For example, in one embodiment, the recess is formed by removing a damaged portion of the substrate. The recess is shaped to transfer tensile stresses from the substrate to the insert regardless of the quality of a weld or other attachment structure between the insert and the substrate. In some embodiments, the insert receives the tensile stresses from the substrate via shear along the perimeter of the insert. In each embodiment, the insert facilitates increasing the strength of the repair.
Unless otherwise indicated, approximating language, such as “generally,” “substantially,” and “about,” as used herein indicates that the term so modified may apply to only an approximate degree, as would be recognized by one of ordinary skill in the art, rather than to an absolute or perfect degree. Approximating language may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be identified. Such ranges may be combined and/or interchanged, and include all the sub-ranges contained therein unless context or language indicates otherwise.
Additionally, unless otherwise indicated, the terms “first,” “second,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, for example, a “second” item does not require or preclude the existence of, for example, a “first” or lower-numbered item or a “third” or higher-numbered item.
As used herein, the terms “axial” and “axially” refer to directions and orientations extending substantially parallel to a longitudinal axis of a rotary machine. Moreover, the terms “radial” and “radially” refer to directions and orientations extending substantially perpendicularly to the longitudinal axis of the rotary machine. In addition, as used herein, the terms “circumferential” and “circumferentially” refer to directions and orientations extending arcuately about the longitudinal axis of the rotary machine. The term “fluid” as used herein includes any medium or material that flows, including, but not limited to, air. As used herein, the term “component” refers to any structure within a rotary machine that may be subject to tensile stresses. In addition, although embodiments of the disclosure are described with reference to components of rotary machines, it should be understood that the scope of the disclosure encompasses any suitable component of any suitable structure for which the embodiments are enabled to function as described herein.
In the exemplary embodiment, each rotor blade 126 includes an airfoil 130. Additionally, each rotor blade 126 includes a dovetail 134 coupled to rotor disk 112. Dovetail 134 is inserted axially within a suitably-shaped slot 136 defined in rotor disk 112. During operation, a flow 138 of hot combustion gases is channeled through a rotor/stator cavity 140 exposing airfoil 130 to flow 138 causing rotation of disk 112 and subjecting rotor blades 126 to centrifugal forces.
In certain embodiments, substrate 202 may be subjected to tensile stress 204 during operation of rotary machine 100 (shown in
A first direction 206 is defined as being substantially parallel to the direction of tensile stress 204 in the component to which insert 200 is coupled. For example, during operation of rotary machine 100, rotor blade 126 is exposed to centrifugal forces during rotation about axis 110 (shown in
To repair damage to substrate 202, the damaged area is removed from substrate 202, to create a recess 210 within substrate 202. In the exemplary embodiment, recess 210 extends within substrate 202 from a surface 212 of substrate 202 to a depth defined within substrate 202 that is beyond a depth of the damage, such that the entire damaged section is removed from substrate 202. In alternative embodiments, recess 210 is created to any suitable size that enables insert 200 to function as described herein. In the exemplary embodiment, recess 210 is formed by machining substrate 202. In alternative embodiments, recess 210 is formed via any suitable method that enables repair of substrate 202 as described herein.
In the exemplary embodiment, recess 210 includes a first portion 214, a second portion 216, and a third portion 218 defined between first portion 214 and second portion 216 with respect to first direction 206. First portion 214 has a first width 220 defined substantially parallel to second direction 208, second portion 216 has a second width 222 defined substantially parallel to second direction 208, and third portion 218 has a third width 224 defined substantially parallel to second direction 208. In the exemplary embodiment, first portion 214 and second portion 216 are each generally elliptical, and third portion 218 extends from first portion 214 to second portion 216 in a substantially rectangular shape. In alternative embodiments, first portion 214, second portion 216, and/or third portion 218 may have any suitable shape that enables insert 200 to function as described herein.
In the exemplary embodiment, first portion 214 is formed on a first side of the damaged area with reference to first direction 206, second portion 216 is formed on an opposite second side of the damaged area with reference to first direction 206, and third portion 218 is formed therebetween, such that the damaged area is substantially removed from substrate 202. Specifically, recess 210 is sized such that not only the damaged area of substrate 202 is removed, but also non-damaged portions of substrate 202, such as first portion 214 and second portion 216, to facilitate increasing strength of the repair.
In the exemplary embodiment, first width 220 of first portion 214 and second width 222 of second portion 216 are each more than third width 224 of third portion 218. In certain embodiments, first width 220 of first portion 214 and second width 222 of second portion 216 are each more than twice third width 224 of third portion 218. First portion 214, second portion 216, and third portion 218 cooperate to define a perimeter of recess 226 in substrate 202. In the exemplary embodiment, insert 200 has a perimeter 228 that is sized approximately identically to that of recess perimeter 226, such that insert 200 is received within recess 210 in a clearance fit. The relationship of first width 220, second width 222, and third width 224 ensures that tensile stress 204 induced parallel to first direction 206 are effectively transferred to insert 200 from portions of substrate 202 surrounding recess 210, as will be described herein, and regardless of the strength of a bond formed between insert 200 and substrate 202.
In the exemplary embodiment, insert 200 is coupled to substrate 202 via a brazed metallurgical bond between adjacent faces of insert 200 and substrate 202 and/or between recess perimeter 226 and insert perimeter 228. The brazing process includes placing a brazing tape and/or brazing paste with a relatively low melting temperature between and/or on insert 200 and substrate 202, and then heating the braze material to a high temperature. The high temperature melts the braze material and fuses insert 200 and substrate 202 without melting either insert 200 or substrate 202. The brazed metallurgical bond is stronger under shear than in tension and seals insert 200 within substrate 202 preventing working fluid within rotary machine 100 (shown in
In operation, tensile stress 204 induced within substrate 202 substantially parallel to first direction 206 are transferred to insert 200 at first portion 230 and second portion 232. More specifically, tensile stress 204 within substrate 202 are received by first portion 230 at an interface 236 defined between recess perimeter 226 and insert perimeter 228, and received within second portion 232 at an interface 238 defined between recess perimeter 226 and insert perimeter 228. Thus, tensile stress 204 are transferred directly from substrate 202 to insert 200 without relying on a tensile strength of the metallurgical bond and/or weld between insert 200 and substrate 202, such that a load carrying capacity of insert 200 is increased. Moreover, in certain embodiments, because first width 220 of first portion 214 and second width 222 of second portion 216 are each more than twice as wide as third width 224 of third portion 218, interface 236 and interface 238 each have a width at least equal to third width 224. The metallurgical bond and/or weld are sufficiently strong to inhibit insert 200 from decoupling from substrate 202 in a direction substantially normal to surface 212 during operation of rotary machine 100.
In some embodiments, insert 200 is formed from a second material that has at least one of a tensile strength, creep resistance, and fatigue resistance, such as low-cycle fatigue, that is greater than the first material from which substrate 202 is formed. For example, insert 200 is formed from a suitable high gamma prime superalloy, such as a nickel-based superalloy, that has a tensile strength greater than a tensile strength of a material from which substrate 202 is formed. The greater tensile strength of the second material facilitates insert 200 carrying a tensile load applied across first width 220 and second width 222 through the narrower third width 224. In alternative embodiments, the second material from which insert 200 is formed is any other suitable material that enables insert 200 to function as described herein. For example, insert 200 is formed from a substantially identical material to the first material of substrate 202.
Similarly, first width 220 of first portion 214 and second width 222 of second portion 216 are each more than third width 224 of third portion 218. However, in this exemplary embodiment, recess 210 has a substantially dovetail shape at first and second portions 214 and 216, and insert 200 has a corresponding substantially dovetail shape at first and second portions 230 and 232. In alternative embodiments, each of recess 210 and insert 200 has any suitable shape that enables insert 200 to function as described herein. In operation, tensile stress 204 induced within substrate 202 are received within first portion 230 at a plurality of interfaces 236 and received within second portion 232 at a plurality of interfaces 238. Thus, tensile stress 204 are transferred directly from substrate 202 to insert 200 without relying on a tensile strength of the metallurgical bond and/or weld between insert 200 and substrate 202. Insert 200 is coupled to substrate 202 as described previously. Also as described previously, in certain embodiments, insert 200 is formed from a second material that has a tensile strength greater than a tensile strength of the first material from which substrate 202 is formed, and in some embodiments, the ratio of tensile strength of the second material to the tensile strength of the first material is greater than or equal to the ratio of first width 220 and/or second width 222 to third width 224.
In certain embodiments, perimeters 226 and 228 define a plurality of perimeter portions 246 each aligned at an acute angle 242 relative to first direction 206. For example, in the exemplary embodiment, first portion 230 and second portion 232 of insert 200 each define two portions 246 of perimeter 228 having respective acute angles 242 with respect to first direction 206. Insert 200 is coupled to substrate 202 by a brazed metallurgical bond at least between recess perimeter 226 and insert perimeter 228. Respective acute angles 242 are selected such that the brazed metallurgical bond is substantially in shear when substrate 202 is subjected to tensile stress 204. For example, each acute angle 242 is less than or equal to about 30 degrees. For another example, each acute angle 242 is less than or equal to about 20 degrees. In alternative embodiments, each acute angle 242 has any suitable value and/or insert 200 has any other suitable shape that enables insert 200 to function as described herein.
In operation, tensile stress 204 is transferred to insert 200 through shear stress 240 along the brazed metallurgical bond. Because such brazed metallurgical bonds are stronger under shear than under tension, the plurality of portions 246 of recess perimeter 226, and thus of insert perimeter 228, each aligned at an acute angle 242 relative to first direction 206 enable a substantial proportion of tensile stress 204 to be transferred through insert 200 with a decreased risk of failure of the brazed metallurgical bond. Thus, a load carrying capacity of insert 200 is increased.
Although the embodiments illustrated in
An exemplary method 300 for repairing a component of a rotary machine, such as rotor blade 126 (shown in
In certain embodiments, method 300 includes creating 306 a brazed metallurgical bond defined between the insert and the substrate. Additionally or alternatively, method 300 includes welding 308 the insert to the substrate. Additionally or alternatively, method 300 further includes configuring 310 the insert to receive tensile stress substantially parallel to the first direction from the substrate when the rotary machine is in operation.
In certain embodiments, the recess perimeter includes a plurality of perimeter portions, such as perimeter portions 246, that are each aligned at an acute angle, such as acute angles 242, relative to the first direction, and method 300 further includes creating 312 a brazed metallurgical bond defined between the insert and the substrate along the plurality of perimeter portions such that the brazed metallurgical bond is in shear when the substrate is subjected to the tensile stress.
Exemplary embodiments of repair inserts and methods for repairing a component of a rotary machine are described above in detail. The embodiments described herein provide several advantages in repairing rotary machine components. Specifically, the repair insert and methods described herein facilitate increasing the strength of the repair and reducing or eliminating a need for structural weld repair. Some embodiments described herein provide advantages in that the repair insert receives tensile stress directly from the substrate, without a need to rely on a bond created between the insert and the substrate. Certain embodiments provide an advantage in that tensile stress in the substrate are transferred to the repair insert substantially through shear in a brazed metallurgical bond, which performs better than a brazed metallurgical bond subjected to tensile stress. The repair inserts and method described herein enable a higher strength of repair to damaged rotary machine components thus increasing service life.
The repair inserts and methods described herein are not limited to the specific embodiments described herein. For example, components of each system and/or steps of each method may be used and/or practiced independently and separately from other components and/or steps described herein. In addition, each component and/or step may also be used and/or practiced with other assemblies and methods.
While the disclosure has been described in terms of various specific embodiments, those skilled in the art will recognize that the disclosure can be practiced with modification within the spirit and scope of the claims. Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. Moreover, references to “one embodiment” in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. In accordance with the principles of the disclosure, and feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
