Patent Application
20140117007
None.
The disclosed embodiments generally pertain to thermal management and heat treatment of turbine engine components. More particularly present embodiments pertain to methods for localized thermal management and heat treatment for engine components.
In a gas turbine engine, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases, which flow downstream through turbine stages. These turbine stages extract energy from the combustion gases. A high pressure turbine first receives the hot combustion gases from the combustor and includes a stator nozzle assembly directing the combustion gases downstream through a row of high pressure turbine rotor blades extending radially outwardly from a supporting rotor disk. In a two stage turbine, a second stage stator nozzle assembly is positioned downstream of the first stage blades followed in turn by a row of second stage rotor blades extending radially outwardly from a second supporting rotor disk. This results in conversion of combustion gas energy to mechanical energy.
The first and second rotor disks are coupled to the compressor by a corresponding high pressure rotor shaft for powering the compressor during operation. A multi-stage low pressure turbine may or may not follow the multi-stage high pressure turbine and may be coupled by a second shaft to a fan disposed upstream from the compressor.
As the combustion gas flows downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced. The combustion gas may continue through multiple low stage turbines. This rotates the shafts which in turn rotates the one or more compressor.
The compressor, turbine and the bypass fan may have similar construction. Each may have a rotor assembly including a rotor disc and a set of blades extending radially outwardly from the rotor disc. The compressor, turbine and bypass fan share this basic configuration. However the materials of construction of the rotor disc in the blades as well as shapes and sizes of the rotor discs and blades vary in these different sections of the gas turbine engine. The blades may be integral with and metallurgically bonded to the disk. This type structure is called a blisk (“bladed disk”). Alternatively, the blades may be mechanically attached to the disk, such as by dovetail connection. Alternative to disks, drums may be utilized.
During operation, it becomes necessary to periodically repair engine components, such as for example, blades, case, frame, and/or blisk in local areas. For example, turbine and compressor blades may receive foreign object damage, such as by entrained particles in the gas flow that impinge the blade, over a period of time of service. Other sources of damage include tip rubbing, oxidation, thermal fatigue cracking, and erosions from the sources described above. Eventually, portions of the blade may need replacement. Sometimes this requires replacement of a tip portion. Other times, larger portions of the blade must be replaced. Since only limited segments of the blades typically have foreign object damage, it is desirable to replace only the sections containing the damage.
One problem with replacement of portions of workpieces or engine components is that the existing portions of the component and the disk or drum become heat sinks when the replacement portion of the workpiece or engine component is welded on. This can change the metallurgy of the existing components and the disk or drum in area away from the weld area, which is highly undesirable. For example, when titanium based metal are used, they may also form alpha case on the surface of the metal. For example, heating of certain materials over approximately 315 degrees C. (600 degrees F.) may result in development of a brittle layer of undesirable build up on the component, for example alpha case. Advanced engine components have critical dimensions, that may be altered or damaged by heat treatments of the entire component. This alpha case then must be removed by chemical processing, which removes metal from the part. This can result in change in tolerances in parts rendering them unsuitable for use.
After the replacement part is welded on, the replacement part may also need to be heat treated to relieve stress. However, it is desirable that heat application or exposure does not cause damage or weakening of the previously undamaged portions of the airfoil. This local treatment is more desirable than subjecting the entire part to thermal cycles.
One problem with known local heat treatment methods is that process control methods have been lacking. As a result, the components may be over heated or under heated. The use of local heat treatment has been limited.
It would be desirable to reduce or eliminate these and other problems associated with in situ localized welding and subsequent heat treatment.
It is further desirable that surface oxidation or alpha case formation be limited and that repaired components maintain stringent requirements of dimensional accuracy, microstructure, and mechanical performance for example.
According to at least one embodiment, A method of thermal management for engine components comprises positioning an engine component in at least one tool, positioning a first tool section on the engine component, positioning a second tool section on the engine component, heating a localized area of said engine component with at least one heater block, passing a cooling fluid to cooling portions of the first and second tool sections away from the area of the workpiece being heat treated, limiting heat dissipation through the workpiece with the cooling fluid, managing cooling time of the heat treatment of the workpiece.
According to an alternate embodiment, a method of thermal management, comprises positioning a first workpiece and a second workpiece in at least one tool having internal cavities, passing a fluid into at least one of the internal cavities to cool portions of the first and second workpieces, welding the first workpiece and the second workpiece in the at least one tool by resistance heating to form a joined workpiece, controlling a rate of cooling of the joined workpiece to slow a rate of cooling through at least one of a resistive heat element or welding electrode of the at least one tool.
According to still an further embodiment, a localized thermal management tool, comprises a mounting block, a first heater block having a first workpiece engagement surface, a second heater block having a second workpiece engagement surface, a resistive heater mounted within at least one of the first heater block and the second heater block, a first cooling clamp engaging the mounting block and the first heater block, a second cooling clamp engaging the mounting block and the second heater block, a cooling fluid conduit disposed in at least one of the first and second cooling clamps, an insulator between each of the heater blocks and the cooling clamps.
According to further embodiments, a method of heat treating an engine component comprises welding a first portion of an engine compartment on a second portion of said first portion of said engine component, positioning the engine component in a fixture at a heat treatment station, positioning at least one of the first portion and the second portion in an induction coil, applying current to the coil and, heat treating the at least one of the first portion and the second portion.
According to even further embodiments, a method of heat treating an engine component comprises connecting a disk having a plurality of titanium components to a fixture, positioning one of the titanium components into an induction coil loop, providing an alternating current to the induction coil loop, heat treating the titanium component positioned in the induction coil loop and, monitoring a temperature of the heat treating.
Embodiments of the invention are illustrated in the following illustrations.
Reference now will be made in detail to embodiments provided, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not limitation of the disclosed embodiments. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to still yield further embodiments. Thus it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Referring to
As used herein, the terms “axial” or “axially” refer to a dimension along a longitudinal axis of an engine. The term “forward” used in conjunction with “axial” or “axially” refers to moving in a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” used in conjunction with “axial” or “axially” refers to moving in a direction toward the engine nozzle, or a component being relatively closer to the engine nozzle as compared to another component.
As used herein, the terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis of the engine and an outer engine circumference. The use of the terms “proximal” or “proximally,” either by themselves or in conjunction with the terms “radial” or “radially,” refers to moving in a direction toward the center longitudinal axis, or a component being relatively closer to the center longitudinal axis as compared to another component. The use of the terms “distal” or “distally,” either by themselves or in conjunction with the terms “radial” or “radially,” refers to moving in a direction toward the outer engine circumference, or a component being relatively closer to the outer engine circumference as compared to another component.
Referring initially to
The axis-symmetrical shaft 24 extends through the through the turbine engine 10, from the forward end to an aft end. The shaft 24 is supported by bearings along its length. The shaft 24 may be hollow to allow rotation of a low pressure turbine shaft 28 therein. Both shafts 24, 28 may rotate about the centerline axis 26 of the engine. During operation the shafts 24, 28 rotate along with other structures connected to the shafts such as the rotor assemblies of the turbine 20 and compressor 14 in order to create power or thrust depending on the area of use, for example power, industrial or aviation.
Referring still to
Referring now to
Referring now to
The workpiece may be various types of engine components. For purpose of explanation, an airfoil or blade is shown in the instant embodiment. However, this should not be considered a limiting shape for a workpiece. The blade may include a pressure side and a suction side extending between leading and trailing edges of the airfoil.
Each of the first workpiece receiving section 32 in the second workpiece receiving section 34 includes a resistance heating element 40 extending into the sections 32, 34. A plurality of slits 42 also define a portion of a welding electrode and are depicted along the upper electrode surface of the tool 30 which are utilized to provide uniform clamping pressure, electrical current flow, and heat sinking for welding as will be described further herein. The heating elements 40 provide supplemental preheating, post heating or both to control the cooling rate of the workpiece following the weld process. This also allows for more controlled heating and cooling of selected locations in a localized manner as opposed to heating an entire workpiece.
Adjacent the resistive heating element 40 is a layer of insulation 50 for the tool 30. The insulation 50 limits heat transfer through the tool 30 thus aiding to localize the heat treatment. The insulation 50 also separates the welding electrode portions of 36, 38 from the clamps 48 so that the clamps 48 are not electrified and do not bond to the blocks 36, 38. Finally, the insulation separates the heated portion of the tool 30 from the cooled portion of the tool.
Extending into each of the workpiece receiving sections 32, 34 are pairs of fluid cooling tubes 60, 62. The tubes 60, 62 are in fluid communication with a portion of the tool 30. For example, according to one embodiment, the tubes 60, 62 are press fit into two sides of the tool 30. Specifically, the tubes 60, 62 are positioned in the sockets 73 (
Referring now to
Each cooling clamp 48 retains the first heater 36 in position relative to the mounting block 46. The clamps 48 are positioned through a channel 49 of the first and second heaters 36, 38 and may be connected and aligned with the mounting block 46. Each of the clamp structures 48 has a curved surface 70 to approximate the workpiece 31 surface and conform thereto. In the present embodiment, the workpiece 31 is shown as an airfoil. Accordingly, the curved surface 70 of the clamps 48 which engages the workpiece 31 approximates either the pressure side or the suction side of the exemplary airfoil. However, other engine components or workpieces 31 may be utilized in accordance with the instant disclosure. The curved surface 70 may be formed of a heat resistant material.
As depicted in the figures, the slits 42 extend in from the lower surface of the first and second electrodes 36, 38 and continue upwardly along contoured surfaces 82 to the top of the heater blocks 36, 38. The slits 42 allow for the metal heater blocks 36, 38 to conform to the shape of the workpiece 31 and further allow for the heating and cooling process, expansion and contraction, that occurs. The surface 82 is contoured to provide a work surface against which the workpiece engages. The surface 82 may be formed of hardened or heat resistant material. Without the contour allowed by the slits 42 the entire surface of the workpiece 31 would not be in contact with the heater blocks 36, 38. The slits 42 also retain electrical leads which provide the welding heat necessary for SSRW joining two portions of workpieces 31. The leads disposed within the slits 42 extending through this area provide localized heating in the area where the treatment is to occur. The slits 42 area of the blocks 36, 38 provide welding heat for the joining parts. Additionally, slit areas also may be used to slow the cooling by providing pulse-type current to the part in order to slow cooling.
Each of the clamps 48 includes a plurality of alignment apertures 72 which align with aperture 74 in the mounting block 46. Dowels, rods, fasteners or other such structure maybe position through these apertures to retain the clamp together with the mounting block and intern retain the first and second heater blocks 36, 38 together against the workpiece.
The first and second heater blocks 36, 38 also provide a cavity 78 (
An insulation element or insulator 50 is positioned above the clamp 48 between the cooling clamps 48 and the heater blocks 36, 38. The insulation 50 inhibits the heaters 40, blocks 36, 38 from heating the clamps 48 in an undesirable manner. Thus the heat is limited to the heater blocks 36, 38 and the local area of the workpiece 31 so that the localized heating solely affects the workpiece. Moreover, the heat of the heater blocks 36,38 is limited from passing to the clamps 48 which are cooling the adjacent portions of the workpiece 31.
The fluid cooling tubes 60, 62 are depicted extending through into the clamps 48 through sockets 73 the clamp structure 48. The fluid cooling tubes provide a means of thermal management for the tool 30. Fluids such as liquid or gas form may be utilized to communicate with the clamps 48. The cooling inhibits the heater blocks 36, 38 from heating the cooling clamps 48. With the clamps staying cooler, the heat from the heater blocks 36, 38 is inhibited from metallurgically changing the portions of the workpiece 31 adjacent to where the welding is occurring.
Referring now to
Referring now to
Referring now to
In operation, the workpiece 31 is disposed in at least one of the first heater block/electrode 36 and the second heater block 38. According to the instant embodiment, a weld seam extends about the entire workpiece so both heater blocks/electrodes are utilized so that the entire weld line may be heat treated. The heater blocks 36, 38 are positioned adjacent the mounting block 46 and cooling clamps 48. Dowels, rods, fasteners or other structure may be utilized to connect the clamps 48 to the mounting block 46, through apertures 72, 74 and retain the heater blocks 36, 38 in place. An insulator 50 is positioned between the heater blocks 36, 38 and the clamps 72.
Next, cooling tubes 60, 62 are connected to a fluid source so that a fluid may flow into the clamps 48. The fluid may be liquid or gas and keeps portions of the workpiece not contacting the heater blocks 36, 38 from becoming a heat sink. This limits metallurgical change in unwelded portions of the workpiece 39 and the disk 39.
When the tool 30 is constructed, with the workpiece, a resistance heater 40 is activated. The cooling fluid serves two functions. The fluid keeps the workpiece 31 cooler in areas not directly being heated. Additionally, the cooling fluid inhibits the unheated portions of the workpiece, as well as other pieces such as the blisk or disk from becoming a heat sink. The rate of cooling is slowed so that the heat treatment does not adversely affect those components of the workpiece. The cooling rate may additionally be slowed by heating the resistors 40, or by passing current through the welding electrodes 42, or both after the welding process is complete, thus preventing the workpiece from cooling too quickly.
Referring now to
Adjacent to the fixture 132, the station 130 includes a mount 140. The mount 140 extends upwardly but may extend in various directions as well. At the top of the mount 140, an induction heat station 142 is positioned. The station 142 includes an induction coil 144 extending outwardly. The coils 144 form a loop 146 wherein a tip of the blades 131 is positioned.
As mentioned with reference to
Once the blade tips 133 are disposed on the blades 131, these weld lines must be heat treated. The heat treatment provides for stress relief of the blade. The localized heat treatment however is desirable in order to inhibit buildup of oxidation or alpha case to only the weld repaired area of the entire part. For example, with titanium based materials, the heat treatment may cause alpha case build up on the metal as previously described and which must be removed before service.
The heat treatment station 130 allows for selected heat treatment of the specific weld area of the blade at the joint with the weld tip 133. In this manner, the entirety of the blade 131 need not be heat treated. Instead, the portion of the blade needing stress relief, i.e. the weld repaired area, can be heat treated. Additionally, the side effects of the heat treating process do not affect remainder of the blade and disk.
Referring now to
Also shown in
The foregoing description of structures and methods has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. Features described herein may be combined in any combination. Steps of a method described herein may be performed in any sequence that is physically possible. It is understood that while certain forms of a local heat treatment process and apparatus have been illustrated and described, it is not limited thereto and instead will only be limited by the claims, appended hereto.
While multiple inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the invent of embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
Examples are used to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the apparatus and/or method, including making and using any devices or systems and performing any incorporated methods. These examples are not intended to be exhaustive or to limit the disclosure to the precise steps and/or forms disclosed, and many modifications and variations are possible in light of the above teaching. Features described herein may be combined in any combination. Steps of a method described herein may be performed in any sequence that is physically possible.
All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.
It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
