Patent Application
20080095590
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:
The exemplary turbofan engine 10 is in the form of a high bypass ratio engine mounted within a nacelle assembly 24 in which most of the air pressurized by the fan assembly 14 bypasses the core engine itself for generating propulsion thrust. The fan air F is discharged from the engine 10 through a fan nozzle section 28 defined radially between a core nacelle 30 and a fan nacelle 32. The core exhaust gases C are discharged from the core engine through a core exhaust nozzle 34 defined between the core nacelle 30 and a center plug 36 disposed coaxially therein around an engine longitudinal centerline axis A of the engine 10 and nacelle.
The fan assembly 14 includes a plurality of circumferentially spaced fan blades 38 which may be made of a high-strength, low weight material such as a titanium alloy. An annular blade containment structure 40 is typically disposed within a fan case 42 immediately surrounding the path of blades 38 to receive blade fragments which may be accidentally released and retaining them without permitting them to become free projectiles exterior to fan jet engine 10.
A rub strip 46 is located within the containment structure 40 against which blade tips 44 of the fan blades 38 are closely fitted to provide a sealing area for reducing the amount of air leaking past the blade tips 44. The rub strip 46 is manufactured of a material which may be in intermittent contact with the tips 44 of the blades 38 during operation.
Referring to
The mount 52 is preferably manufactured for mounting to a fan hub 60 of the LPT/Fan rotor shaft assembly 22L once the fan blades 38 are removed therefrom such that the machining tool 50 is rotatable about axis A in conjunction with rotation of the LPT/Fan rotor shaft assembly 22L. That is, the machining tool 50 replaces the fan blades 38 and mounts to the rotor shaft assembly 22 utilizing the spinner bolt circle structure 62 (
The beam 54 is preferably a tubular member which is rectilinear in crosssection. The beam 54 is fixed to the mount 52 and is preferably of a length just shorter than the diameter of the fan case 42. The beam 54 supports the cutting tool assembly 56 toward one end segment (also shown in
Referring to
In operation, the fan blades 38 are removed from the LPT/Fan rotor shaft assembly 22L subsequent to a determination that interference between the rub strip 46 and the fan blade tips 44 are improper or subsequent to fan rub strip 46 replacement. The in situ fan case rub strip machining tool 50 is then mounted to the LPT/Fan rotor shaft assembly 22L. The tool motor 62 is then positioned relative the compound milling table 60 to position the tool bit 64 relative the axis A. The tool motor 62 is then spun up and the in situ fan case rub strip machining tool 50 is rotated about the axis A in combination with the LPT/fan rotor shaft assembly 22L. The in situ fan case rub strip machining tool 50 may be rotated manually (by hand) such that the rub strip 46 is evenly and precisely machined to be concentric with the axis A to assure proper fan blade tip to rub strip interface. Alternatively, the tool 50 may be rotated mechanically through a motor drive system or the like.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention.
The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.
