Patent Application
20100329873
1. Field of the Invention
The invention relates to an assembly for preventing aft movement of a blade disposed in a slot and for sealing against a platform of the blade.
2. Description of Related Prior Art
U.S. Pat. No. 5,501,575 discloses a fan blade attachment for gas turbine engines. A sloped deep slot is formed in the rim of a disk for accepting the dovetail of a root of the fan or compressor blade allowing the removal of a single blade from the disk. A segmented retainer plate is disposed at the aft end of the blade root and bears against the blade root to react out the slope induced axial blade loads, providing a low hub-tip ratio configuration. An annular shaped seal plate is adjacent to a platform of the blade and is utilized so as to prevent recirculation of the air in the attachment at the rim of the rotor disk.
In summary, the invention is a fan blade retaining and sealing ring assembly for an aft side of a bladed disk assembly. The ring assembly includes an inner ring operable to prevent aft movement of a fan blade positioned in a slot formed in a blade disk. The ring assembly also includes an outer ring operable to seal against a platform of the fan blade. The inner ring and the outer ring are formed from different materials.
Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
The invention, as exemplified in the embodiment described below, can be applied to substantially reduce the cost of retaining fan blades and sealing the bladed disk assembly. In the exemplary embodiment, the application of the invention can reduce the cost of the retaining and sealing structures by 40%. The basis of the cost savings will be described below.
Referring to
A nose cone assembly 28 can be attached to the fan 14. As set forth above and shown in
A fan blade retaining and sealing ring assembly 34 can be disposed adjacent to an aft side of the bladed disk assembly 14. The ring assembly 34 includes an inner ring 36 operable to prevent aft movement of the fan blade 32. The ring assembly 34 also includes an outer ring 38 operable to seal against a platform 40 of the fan blade 32. The inner ring 36 and the outer ring 38 are formed from different materials. The respective cross-sections of the inner and outer rings 36, 38 shown in
The inner ring 36 can be formed from a first material defining a first strength and the outer ring 38 can be formed from a second material defining a second strength less than the first strength. For example, the inner ring 36 can be formed from titanium and the outer ring 38 can be formed from aluminum. The inner ring 36 can be subjected to higher loading than the outer ring 38 and can therefore be formed from a stronger material. Thus, in the exemplary embodiment, the amount of relatively stronger material that is used can be minimized. Relatively stronger material can be used only for the portion of the ring assembly 34 applied to retain the fan blade 32 and not the portion used to seal. Generally, stronger material can be more expensive and/or heavier.
The outer ring 38 can be formed from a material that is more machinable than the material from which the inner ring 36 is formed. The term machinability refers to the ease with which a material can be removed. Cutting and grinding are two processes by which material is removed from a work-piece. Materials with relatively greater or higher machinability require relatively lower power for material removal. Also, materials with relatively greater or higher machinability impart relatively lower wear on the tooling. In most cases, the strength and toughness of a material are the primary factors relating to machinability. However, other factors affect machinability, including the composition of the material, the thermal conductivity, the cutting tool geometry, and the machining process parameters.
As set forth above, forming the ring assembly 34 with different materials can reduce cost by minimizing the amount of stronger material that is used in forming the ring assembly 34. Bifurcating the structures of the ring assembly 34 applied for retaining and for sealing can also reduce cost by simplifying the design of the less-machinable structure. For example, a sealing surface is generally more costly to produce that a general load-bearing surface. Generally, the sealing surface must usually define a particular surface finish which can increase cost. Also, the geometric position of a sealing surface is usually subject to a tighter tolerance and tighter tolerances generally increase cost. In the exemplary embodiment, the inner ring 36 can define a load bearing surface 42 and the outer ring 38 can define a sealing surface 44. Thus, the less machinable portion of the ring assembly (the inner ring 36) can be a relatively simple ring shape. The sealing surface 44 can be defined by the more machinable outer ring 38. Also, the usage of separate sealing and retention components can result in lower input material volume compared to a single-component (with single forging or plate) design. Therefore, the volume of material to be removed via machining operations is significantly reduced.
The outer ring 38 can contact the blade disk 30 at a radially inner and axially-facing surface 58. The outer ring 38 can contact the platform 40 at the sealing surface 44. The sealing surface 44 is radially-spaced from the surface 58. The outer ring 38 can be axially spaced from the blade disk 30 along at least part of the radial distance between the surface 58 and the sealing surface 44.
The inner ring 36 and the outer ring 38 can be centered on a common axis and abut one another along the axis. In the exemplary embodiment, the common axis can be the centerline axis 24 (shown in
The inner ring 36 can also include apertures 50. The blade disk 30 can include corresponding apertures 52. The apertures 50 and 52 can be aligned to locate the inner ring 36 circumferentially relative to the blade disk 30. Thus, the inner ring 36 can be located relative to the blade disk 30 with at least two structures defined by the inner ring 36.
The exemplary outer ring 38 can include an annular slot 54 in which the inner ring 36 can be received. The inner ring 36 and the outer ring 38 can thus overlap one another axially and radially relative to the centerline axis 24 (shown in
While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. The right to claim elements and/or sub-combinations of the combinations disclosed herein is hereby reserved.
