TURBINE BLADE STAKING PIN
A staking pin for a gas turbine engine is disclosed. The staking pin may include a solid portion extending part of a length of the staking pin, and a hollow portion extending an additional part of the length of the staking pin. The staking pin may be constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.
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This application claims the benefit of U.S. Provisional Application No. 61/680,669, filed Aug. 7, 2012, which is hereby incorporated by reference in its entirety.
TECHNICAL FIELDThe present disclosure is directed to a pin of a gas turbine engine (GTE) and, more particularly, to a staking pin for staking a turbine blade in a turbine rotor disk of the GTE.
BACKGROUNDGTEs produce power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed air. In general, turbine engines have an upstream air compressor coupled to a downstream turbine with a combustion chamber (“combustor”) in between. Energy is released when a mixture of compressed air and fuel is burned in the combustor. The resulting hot gases are directed over blades of the turbine to spin the turbine and produce mechanical power.
Turbine blades and other components of GTEs are subject to high temperatures and high. local stresses during operation. Due to rotation of a turbine rotor disk supporting the turbine blades, the turbine blades experience a centrifugal force, and therefore must be retained within the rotor disk. While a turbine blade root, for example a dovetail, can facilitate retention of the turbine blade, other or additional means to retain the turbine blade can be employed.
U.S. Pat. No. 3,165,294 (“the '294 patent”) describes a locking arrangement for holding blades of a rotor assembly in a fluid flow machine. According to the '294 patent, a rotor drum is provided with a plurality of axially spaced circumferentially extending slots. A radially extending threaded or tapped hole is provided for a plug to be received therein. A blade having a root and a passage is positioned in the slot, and a plug is disposed in the passage. The blade is thus held against radial movement relative to the rotor drum, and the plug also holds an entire row of abutting blade roots against circumferential movement in the slot. The '294 patent further notes that during rotation of the rotor drum, centrifugal force urges the plug out of the threaded or tapped hole and into a locking direction.
SUMMARYIn one aspect, a staking pin for a gas turbine engine is disclosed. The staking pin may include a solid portion extending part of a length of the staking pin, and a hollow portion extending an additional part of the length of the staking pin. The staking pin may be constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.
In another aspect, a gas turbine engine is disclosed. The gas turbine engine may include a compressor system, a combustor system, and a turbine system. The turbine system may include at least one turbine rotor disk and a plurality of turbine blades each retained in the turbine rotor disk. At least one of the turbine blades may be retained in the turbine rotor disk by a staking pin constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm, and extending through a portion of the at least one turbine blade
In yet another aspect, a staking pin for a gas turbine engine is disclosed. The staking pin may include a solid portion extending part of a length of the staking pin, and a hollow cylindrical portion including a hole extending an additional part of the length of the staking pin. The cylindrical portion may have a wall thickness of about 1 mm, and the staking pin may be constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.
As shown in
In the installed state, the staking pin 22 may protrude from the platform 12 and into the flow path 18 by a protrusion distance 200. The protrusion distance 200 may be between about 0.254 mm to about 0.762 mm (about 0.010 inches to about 0.030 inches). In some instances, the protrusion distance 200 may be less than about 0.508 mm (about 0.020 inches). For example, the protrusion distance 200 may be about 0.381 mm (about 0.015 inches). In other instances, it may be possible to install the staking pin 22 so as to be flush with the platform 12, such that the staking pin 22 does not extend into the flow path 18.
The dimensions of the staking pin 22 may have various values. In some instances, the length 400 may be between about 5.000 and 6.000 mm (between about 0.197 and 0.236 inches), for example, about 5.969 mm (about 0.235 inches). The length 406 of the cylindrical portion may be less than or equal to about half the length 400. For instance, the length 406 may be between about 2.000 and 3.000 mm (between about 0.079 and 0.118 inches), for example, about 2.500 mm (about 0.098 inches). That is, the ratio of the length 400 to the length 406 may be, for example, about 3 to 1, about 2 to 1, or, in some instances, about 2.4 to 1. Additionally, the outer diameter 404 may be between about 3.000 and 3.500 mm (between about 0.118 and 0.138 inches), for example, about 3.162 mm (about 0.125). The inner diameter 402 may be about between about 2.000 and 2.500 mm (between about 0.079 and 0.098 inches), for example, about 2.108 mm (about 0.083 inches), or about 2.159 mm (about 0.085 inches). Based on these dimensions, the thickness 408 may be between about 0.500 and 1.500 mm (about 0.020 to 0.059 inches), inclusive, or about 1.0 mm (about 0.039 inches). These values of the various pin dimensions are only examples, as other values may be used.
The staking pin 22 may be constructed from Alloy X material. Alloy X is a wrought nickel based superalloy, which exhibits both heat and oxidation resistance. For instance, a component such as a staking pin made of Alloy X may be oxidation resistant to a temperature of 1,200° C. (2,200° F.); however, oxidation resistance to other temperature values may be possible. Additionally, Alloy X may exhibit high yield and ultimate tensile strengths, such that a minimum ultimate tensile strength (UTS) may be about 655 MPa (about 95 ksi), and a minimum yield strength (YS) may be about 240 MPa (about 35 ksi) at GTE operating temperatures. The Alloy X material used to construct the staking pin 22 may be provided as a bar, sheet, wire, or any other form. In some instances, the staking pin 22 may be machined from either a wrought or cast form of Alloy X. In other instances, the staking pin 22 may be cut from Alloy X weld wire having a diameter substantially equal to the outer diameter 404. A segment of Alloy X material may be formed into a cylindrical shape like that shown in
To install the turbine blade 72 in the turbine system 70, the root 14 of the turbine blade 72 is inserted into a slot 34 of the turbine rotor disk 76 between adjacent disk posts 16. In this position, the hole 36 in the platform 12 of the turbine blade 72 is aligned with the slot 34. In order to secure the turbine blade 72 on the turbine rotor disk 76, the staking pin 22 is positioned above the hole 36 such that the cylindrical portion of the staking pin 22 is adjacent to or in contact with the hole 36. The staking pin 22 is then pushed or struck, for example, at an end of the staking pin 22 opposite the staking pin hole 42, to push the staking pin 22 through the hole 36 and into the slot 34 of the turbine rotor disk 76. The staking pin 22 may be struck manually with a hammer, or manually or automatically with any other instrument. As shown in
In some circumstances, after the staking pin 22 is installed, a turbine blade 72 or staking pin 22 removal or “de-staking” operation may also be performed. A de-staking operation may be performed, for example, at the end of a predetermined service life, or if a problem with the turbine blade 72 is discovered during an inspection. To de-stake a pin 22, an instrument, such as a metallic block, may be used to strike a portion of the staking pin 22 protruding from a surface of the turbine blade platform 12. Doing so may shear the staking pin 22 at a desired location, for example, at a location that is flush with the surface of the platform 12. After the staking pin 22 is successfully sheared, any remaining portions of the pin 22 may be removed from the turbine blade 72 to complete the de-staking operation. In some instances, a new turbine blade 72 having a new, unused staking pin 22 can then be provided. In other instances, however, a new staking pin 22 may be installed in a previously used turbine blade 72 in place of a de-staked pin 22.
INDUSTRIAL APPLICABILITYThe above-disclosed staking pin system can be installed in an apparatus experiencing high temperatures and stresses, such as a GTE. The staking pin system may be installed in the combustor system, any stage of the turbine system, or the compressor system, including the stators. In addition, While being described for use in a GTE, the staking pin can be used generally in applications or industries requiring retention of components subject to, for example, a centrifugal force.
The GTE 100 produces power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed fluid, for example air, from the compressor system 10. Energy is released when a mixture of the compressed air and fuel is burned in the combustor system 20. The fuel injectors 30 direct a liquid or gaseous fuel into the combustor system 20 for combustion. The resulting hot gases are directed through the turbine system 70, past the stages 73, 74, 75, over stator vanes and the turbine blades, to spin the turbine blades 72 and rotors 76 and produce mechanical power. Turbine blades 72 rotating within the turbine system 70 may each include a staking pin 22 disposed through the platform 12 and into the slot 34 of the turbine rotor disk 76.
During turbine operation, the turbine blades 72 may experience high stresses. Turbine blade failures should be prevented as they may damage a GTE, and cause inconvenient and unscheduled shutdowns to repair and/or replace damaged GTE components. If turbine blade staking pins are used, depending on their design, the staking pins may oxidize and fail as a result of crack formation in the pin. As GTEs continue to operate at higher temperatures, there is a need for oxidation-resistant components, such as staking pins, in order to prevent failures and premature shut-downs. Additionally, GTE components may experience corrosion due to, for example, salt or sulfur, leading to failure due to crack formation.
The staking pin 22 according to the present description may provide certain advantages. For example, the material from which the staking pin 22 may be made, i.e., Alloy X, in combination with the microstructure and pin dimensions described above, provide an oxidation-resistant staking pin 22 that may avoid premature degradation after being exposed to the operating temperatures and conditions of the GTE 100. By using the staking pin 22 described in the instant application, the risk of GTE failure and/or having to prematurely replace one of the turbine blades can be reduced.
As described above, Alloy X is a high-strength wrought nickel based superalloy. Due to its high strength, the staking pin 22 is designed so as to prevent significant protrusion of the staking pin 22 from the surface of the platform 12 and into the flow path 18 when the staking pin 22 is installed. Specifically, in some instances, the inner diameter 402 of the staking pin hole 42 is such that the wall thickness 408 of the cylindrical portion is sufficiently thin to enable excellent deformation, or “mushrooming,” of the pin 22 in the slot 34 during installation. Mushrooming in the slot 34 beneath the platform 12 may prevent the staking pin 22 from “backing out” of the hole 36 in the turbine blade platform 12 by locking the pin 22 in the hole 36. This, in turn, can secure the turbine blade 72 and prevent it from migrating in either a forward or aft direction. This may reduce a risk of damage to components, such as the turbine rotor 76 and/or turbine nozzles, in the turbine system 70 of the GTE 100. Either separately or in combination with providing a thin wall in the cylindrical portion of the staking pin 22, the overall length 400 of the pin 22 may be relatively short to limit protrusion of the pin 22 from the surface of the platform 12 when the pin 22 is installed.
In addition to being oxidation-resistant, the staking pin 22 made from Alloy X material is both corrosion and heat resistant, and durable such that the staking pin 22 may withstand the stresses of GTE operation. A staking pin 22 made from Alloy X may also exhibit desirable creep performance to prevent failure due to creep. That is, the staking pin 22 described herein may have less of a tendency than a staking pin made of another material to permanently deform under the influence of stresses, such as high temperatures and loads, during operation. Additionally, the Alloy X from which the pin 22 may be made can be inexpensive and readily available as weld wire having an outer diameter that may be acceptable for the staking pins 22, thereby reducing the time and expense of manufacturing the staking pins 22.
Thus, the disclosed configurations of staking pin 22 may reduce the incidence of damage to staking pin 22, such as damage resulting from cracking due to oxidation. The staking pin 22 may be stable under GTE operating stresses, such that cracking, even in the cylindrical portion at the staking pin hole 42 where cracking may be expected to initiate, can be prevented. Furthermore, the staking pin 22 described herein may last at least as long as the turbine blade 72 in which it is installed. Therefore, unnecessary GTE shutdowns can be avoided, as can possible damage, such as cracking, to the turbine rotor disk post 16 due to removal of a turbine blade 72 whose staking pin prematurely failed.
Additionally, regarding the de-staking operation, using the staking pins 22 described herein enables a relatively simple de-staking operation. While the staking pins 22 securely hold the turbine blades 72 in place during operation, if de-staking is necessary, a brittle failure mode of the staking pins 22 may allow for clean shearing of the pins 22 during de-staking without damaging either the turbine rotor disk 76 or turbine blades 72. For example, the staking pins 22 may be broken or sheared at a location that is flush with a surface of the platform 12. The material from which the pin 22 is made, for example, Alloy X, the microstructure of the pin 22 as described herein, and/or the dimensions of the pin 22, can contribute to the brittle failure mode of the staking pins 22 that allows for clean shearing during de-staking.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed apparatus and method. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system and method. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
Claims
1. A staking pin for a gas turbine engine, comprising:
- a solid portion extending part of a length of the staking pin; and
- a hollow portion extending an additional part of the length of the staking pin, wherein the staking pin is constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.
2. The staking pin of claim 1, wherein the hollow portion is a cylindrical portion including a hole extending the additional part of the length of the staking pin.
3. The staking pin of claim 1, wherein the hollow portion is less than half the length of the staking pin.
4. The staking pin of claim 1, wherein the hollow portion has a wall thickness of between about 0.500 and 1.500 mm.
5. The staking pin of claim 1, wherein the hollow portion has a length of about 2.5 mm.
6. A gas turbine engine, comprising:
- a compressor system;
- a combustor system; and
- a turbine system, wherein the turbine system comprises: at least one turbine rotor disk; and a plurality of turbine blades each retained in the turbine rotor disk, wherein at least one of the turbine blades is retained in the turbine rotor disk by a staking pin constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0,1270 mm and extending through a portion of the at least one turbine blade.
7. The gas turbine engine of claim 6, wherein the staking pin extends into a slot formed in the turbine rotor disk.
8. The gas turbine engine of claim 7, wherein the portion of the staking pin in the slot has a diameter greater than a diameter of a portion of the staking pin extending through the portion of the at least one turbine blade.
9. The gas turbine engine of claim 6, wherein the portion of the at least one turbine blade is a platform, and wherein the staking pin protrudes from a surface of the platform.
10. The gas turbine engine of claim 9, wherein the staking pin protrudes from a surface of the platform by a distance between about 0.254 mm and 0.762 mm.
11. The gas turbine engine of claim 9, wherein the stacking pin protrudes from a surface of the platform a distance of less than or equal to about 0.381 mm.
12. The gas turbine engine of claim 9, wherein the staking pin extends through the platform at a location substantially halfway between two opposite ends of the platform.
13. The gas turbine engine of claim 6, wherein the staking pin includes:
- a solid portion extending part of a length of the staking pin; and
- a hollow portion extending from the solid portion and forming an open end of the staking pin, wherein the hollow portion is less than half the length of the staking pin.
14. The gas turbine engine of claim 13, wherein the hollow portion is a cylindrical portion including a hole extending the additional part of the length of the staking pin
15. The gas turbine engine of claim 14, wherein the cylindrical portion has a wall thickness of between about 0.500 and 1.500 mm.
16. The gas turbine engine of claim 14, wherein the cylindrical portion has a length of about 2.5 mm.
17. A staking pin for a gas turbine engine, comprising:
- a solid portion extending part of a length of the staking pin; and
- a hollow cylindrical portion including a hole extending an additional part of the length of the staking pin, wherein the cylindrical portion has a wall thickness of about 1 mm, and wherein the staking pin is constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.
18. The staking pin of claim 17, wherein the staking pin has a total length of about 6 mm.
19. The staking pin of claim 18, wherein the cylindrical portion has a length less than half the total length.
20. The staking pin of claim 17, Wherein the Alloy X material forming the staking pin has non-uniform grain sizes wherein the grains have an average diameter of between about 0.0449 and 0.0750 mm.
Type: Application
Filed: Jan 29, 2013
Publication Date: Sep 25, 2014
Applicant: Solar Turbines Incorporated (San Diego, CA)
Inventor: Solar Turbines Incorporated
Application Number: 13/752,532
International Classification: F01D 5/30 (20060101);