Abstract:
A system and method for repairing a hollow fan blade. In one aspect the blade includes a hollow portion having a plug disposed therein, wherein the plug is smaller than the opening. During processing the blade is located under a vacuum box and the gap is sealed between the plug and the opening using a fiber laser.

Description:
CROSS REFERENCE 
     The present application claims the benefit of U.S. Patent Provisional Application No. 61/190,940, filed Sep. 4, 2008, which is incorporated herein by reference. 
     The present application is related to the U.S. patent application Ser. No. 12/157,330 entitled “SYSTEM AND METHOD FOR COMPONENT MATERIAL ADDITION” filed on Jun. 9, 2008 and incorporated herein by reference. The present application is related to the U.S. Patent Application entitled “SYSTEM, METHOD, AND APPARATUS FOR REPAIR OF COMPONENTS” filed on Jun. 12, 2008 and incorporated herein by reference. 
    
    
     BACKGROUND 
     Repairing hollow fan blades under currently available processes suffers from a few drawbacks. Many current processes may not achieve a repaired fan blade having similar fatigue life to an originally manufactured blade. Further, it is desirable when repairing fan blades that the internal vacuum of the hollow portion of the blade meets manufacturer specifications. Accordingly, there is a demand for further improvements in this area of technology. 
     SUMMARY 
     One embodiment is unique hollow fan blade repair system. Other embodiments include unique systems and methods to add and/or repair the fan blades without internal stress risers and with near-original fatigue life. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  is a schematic illustration of a system for sealing a vacuum in a hollow fan blade. 
         FIG. 2  is an illustration of three material sheets and a blowpipe. 
         FIG. 3  is an illustration of a machined slot. 
         FIG. 4A  is an illustration of a D-shaped cutout. 
         FIG. 4B  is a second illustration of a D-shaped cutout. 
         FIG. 5  is an illustration of a hollow portion of a blade. 
         FIG. 6  is a schematic block diagram of a procedure for sealing a vacuum in a hollow fan blade. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated device, and any further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  is a schematic illustration of a system  100  for sealing a vacuum in a hollow fan blade  102 . The system  100  includes a vacuum box  104 , or enclosure, sufficiently sized to contain a blade  102  including a hollow portion and an opening to the hollow portion. A vacuum box  104  is illustrated, but any device that encloses the component and can be sufficiently sealed is contemplated herein. A hollow fan blade  102  is illustrated, but other components are fully contemplated in the present application, including at least manufactured parts that are at least partially hollow, and further including manufactured parts that have a residual opening from manufacture. Additionally, in certain embodiments, components that are at least partially hollow and have a later formed opening (for example drilled through the component and connecting to a hollow portion) are contemplated herein. 
     The vacuum box  104 , in certain embodiments, includes a door  106  through which the blade  102  passes. The vacuum box  104 , in certain embodiments, further includes a window  108  positioned such that a region of interest  110  on the blade  102  can be accessed optically from a region outside the vacuum box  104 . The region of interest  110  may be a position on the blade  102  where a blowpipe emerges, and/or a region near the opening in the component  102 . In certain embodiments, the system  100  further includes a laser deposition device  112  capable of being positioned within a focal distance of the region of interest  110  on the blade  102 . The focal distance of the laser deposition device  112  depends upon the type of laser in the device  112 , and in certain embodiments the laser is a fibre laser with a focal distance of at least several centimeters. The window  108  includes an optical quality capable of transmitting the laser to an extent allowing deposition operations on the hollow fan blade  102  and that prevents excessive heat build-up in the window from the transmitted laser. 
     In certain embodiments, the laser deposition device includes a laser that aims through the window and a material addition device (e.g. metal powder delivery device) that adds material from within the vacuum box  104 . In certain embodiments, the laser deposition device is within the vacuum box  104 , and may include a camera or visualizing device to ease deposition operations without direct visualization. 
     In certain embodiments, the vacuum box  104  includes a vent  114  and a valve  117  capable of venting the box  104  and holding a significant vacuum in the box  104 . The system  100  further includes, in certain embodiments, a vacuum pump  116 . The vacuum pump  116  is capable of creating a vacuum within the box  104  of a sufficiently high vacuum to meet a manufacturer specification for recommended vacuum in the hollow fan blade  102 . In certain embodiments, the vacuum pump  116  is capable of delivering, and the valve  117  is capable of holding, a vacuum of 0.001 μmHg (microns). In certain embodiments, the valve  117  may hold only a substantial vacuum for a specified period and/or at an acceptable leakage rate. In certain embodiments, vacuum pumps  116  capable of producing greater or lower levels of vacuum are also contemplated herein. 
     In certain embodiments, the system  100  further includes a cutter  118  and/or other machine tool, which may be a machine cutter, laser cutter, a clean carbide cutter, and/or other cutter  118  known in the art. The cutter  118  is structured to machine the blade  102  or portions of the blade  102 . In certain embodiments, the cutter  118  and blade holder (not shown) work together with sufficient control and precision to machine a slot through a selectable number of layers of material sheets that make up the blade  102 . In certain embodiments, the cutter  118  is further structured to machine the blowpipe, the opening, and/or other portions of the blade  102  and the region of interest  110 . In certain embodiments, the blade  102  and/or the cutter  118  may be static, while other devices may be mobile. Further, the cutter  118  may comprise other machine tools for cutting and removing material of a type comprising the blade  102 , and the functions of the cutter  118  may be performed by multiple machine tool devices. In certain embodiments, the material comprising the blade  102  includes titanium and/or a titanium alloy. However, the blade  102  or other component may be any material known in the art including at least steel, aluminum, a composite, a superalloy, and combinations thereof. 
       FIG. 2  is an illustration of three material sheets  202 ,  204 ,  206  and a blowpipe  208 . The blowpipe  208  is illustrated as not inserted into the three material sheets  202 ,  204 ,  206 . In one embodiment, the three material sheets  202 ,  204 ,  206  are stacked, and the blowpipe  208  is inserted into the stack, for example in a slot configured to give the blowpipe  208  access to a hollow region within the stack. In the embodiment, the three material sheets  202 ,  204 ,  206  are placed under heat and pressure sufficient such that the material of the sheets is in a superplastic state, and then pulsed gas is injected through the blowpipe  208  until the sheets  202 ,  204 ,  206  expand to conform to a die (not shown) and form a fan, compressor, and/or turbine blade. The process of forming blades through superplastic deformation is understood in the art and further details are not provided. The blade or component that is at least partially hollow may be any other part formed by any other process, and the embodiment of  FIG. 2  is provided only as one example. 
       FIG. 3  is an illustration of a machined slot  302 . In certain embodiments, the slot  302  is formed by the cutter  118 , and may be formed either before or after the blade  102  is positioned in the vacuum box  104 . In certain embodiments, the slot  302  is formed from removed material from only two of three sheets (e.g.  204  and  206 , but not in  202 ). In one embodiment, the slot  302  is formed from one side only, or from removed material from one side including any layer having an opening  304 , but not from material removed from layers past the opening  304 . In certain embodiments, the opening  304  is included in more than one layer of the blade  102 . In certain embodiments, the slot  302  is formed from any number of layers, including up to all of the layers of the blade  102 . In certain embodiments, the center sheet  206  includes a “D”-shaped cutout  304  which provides access for the blowpipe  208  (already removed in the illustration of  FIG. 3 ) to the hollow region of the blade  102 . In the illustration of  FIG. 3 , the “D”-shaped cutout  304  is an opening to a hollow portion of the blade  102 , but any opening known in the art is also contemplated herein. In certain embodiments, the slot  302  is centered over the opening  304 , but the slot  302  may be formed to include the opening  304  at any position in the slot  302 . In certain embodiments, the opening  304  is formed with a machine tool (e.g. the cutter  118 ) before or after the slot  302  is formed. 
     In certain embodiments, the slot  302  is formed entirely above the hollow region and does not impinge on any of the blade  102  forming the hollow region. In certain embodiments, the blowpipe  208  and the slot  302  are at a blade tip region and do not go down into the body of the blade  102 . In certain embodiments, the slot  302  is formed to include a bottom face  306  that may be flat. In certain embodiments, the bottom face  306  intersects the opening  304 . In certain embodiments, the slot  302  is formed including one or more beveled edges  308 . The bevel angle θ  310  may be any angle, including 90 degrees (i.e. unbeveled). In certain embodiments, θ is about 45 degrees. 
     In certain embodiments, the bottom face  306  of the slot  302  is positioned at least 0.01 inches below or beyond the depth of the blowpipe  208 . In certain embodiments, the bottom face  306  of the slot  302  is machined such that the blowpipe  208  is removed by the formation of the slot  302 . In certain embodiments, the blowpipe  208  is removed before or during the forming of the slot  302 . In certain embodiments, a blowpipe  208  remainder is in the opening  304  or elsewhere in the blade  302 . 
       FIG. 4A  is an illustration of a D-shaped cutout with an inserted plug  402 . The opening  304  includes an inserted plug  402  having a cross-section smaller than the opening  304 . In the illustration of  FIG. 4A , a blowpipe remainder  208  is shown, but the blowpipe remainder  208  may be present or not. In certain embodiments, the plug  402  is sized to form a gap of at least 0.002 inches between the plug  402  and at least one edge of the opening  304 . In certain embodiments, a shim  404  is positioned between the plug  402  and the at least one edge of the opening. The shim  404  should not completely seal the opening  304 . In certain embodiments, the shim  404  has a width of about 0.02 inches, although the shim  404  may be any size that reduces the gap  406  between the plug  402  and the edge of the opening  304  without sealing the gap. In certain embodiments, the shim  404  is positioned over the blowpipe remainder  208 . In certain embodiments, the plug  402  is positioned in the blowpipe remainder  208 . 
       FIG. 4B  is a second illustration of a D-shaped cutout with an inserted plug  402 . The illustration of  FIG. 4B  is consistent with an embodiment of the illustration of  FIG. 4A  wherein an excess plug portion is removed with a machine tool (e.g. the cutter  118 ). In certain embodiments, an excess shim portion is also removed. In certain embodiments, the plug  402  and/or shim  404  are machined to conform with the bottom face  306  of the slot  302 , however the plug  402  and/or shim  404  may be also be slightly raised or depressed relative to the bottom face  306  of the slot  302 . 
     In certain embodiments, the vacuum pump  116  evacuates at least a portion of the gas in the vacuum box  104  before the gap  406  between the plug  402  and the opening  304  is sealed. In certain embodiments, the vacuum box  104  is evacuated after placing the plug  402 , but the evacuation may occur at any time prior to the sealing. In certain embodiments, the vacuum is held for a period—for example about 10 minutes—before the sealing is performed. In certain embodiments, the vacuum is a substantial vacuum, but the vacuum may be any level of vacuum as specified by the manufacturer and/or designer of the blade  102 . For example, the vacuum may be specified as 0.001 μm Hg (i.e. “microns”). In certain embodiments, the laser deposition device  112  or other capable device seals the gap  406  between the plug  402  and the edge of the opening  304 . 
     In certain embodiments, the blade  102  (or other component  102 ) is formed into a specified contour with a laser deposition operation. In certain embodiments, a laser deposition operation utilizing titanium or titanium alloy powder is performed on the blade  102  to restore material removed for the slot and/or to add any other material required to build the blade  102  up to at least the specified contour. In certain embodiments, some material may be removed before or after the deposition operation to bring the blade  102  into conformance with the specified contour. 
       FIG. 5  is an illustration of a hollow portion of a blade  102 . The hollow portion(s)  502  are formed between material sheets  202 ,  204 ,  206  in the illustration of  FIG. 5 . The bottom face  306  of the slot (with the plane of the bottom face  306  shown in  FIG. 5 ) may be above the hollow portion  502  such that the skin of the blade  102  in the hollow portion  502  (i.e. the sheet  202  and sheet  204  in the example of  FIG. 5 ) is not impinged by the slot  302 . The opening  304  is illustrated in the embodiment of  FIG. 5 , which opens into the hollow portion  502 . 
     The schematic flow diagram and related description which follows provides an illustrative embodiment of performing operations for acid fracturing with scale inhibitor control. Operations illustrated are understood to be exemplary only, and operations may be combined or divided, and added or removed, as well as re-ordered in whole or part, unless stated explicitly to the contrary herein. 
       FIG. 6  is a schematic block diagram of a procedure  600  for sealing a vacuum in a component, which in one example may be a fan blade. In certain embodiments, the procedure  600  includes an operation  602  to provide a blade including a hollow portion and an opening to the hollow portion. In certain embodiments, the procedure  600  further includes an operation  604  to machine a slot intersecting the opening into the blade, and an operation  606  to remove a blowpipe. In certain embodiments, the procedure  600  further includes an operation  608  to place a plug in the opening, and an operation  610  to remove an excess portion of the plug. In certain further embodiments, the procedure  600  includes an operation  612  to position a shim between the plug and an edge of the opening. In certain embodiments, the procedure  600  further includes an operation  614  to evacuate gas in an enclosure defining the blade, and an operation  616  to hold the vacuum for a period of time. In certain embodiments, the procedure  600  further includes an operation  618  to seal a gap between the plug and the opening. In certain embodiments, the procedure  600  further includes an operation  620  to form the blade into a specified contour with laser metal deposition and/or machining excess material. 
     As is evident from the figures and text presented above, a variety of embodiments according to the present invention are contemplated. 
     In one exemplary embodiment, a method includes providing a blade including a hollow portion and an opening to the hollow portion, placing a plug in the opening, the plug having a cross section smaller than the opening, evacuating at least a portion of a gas in an enclosure defining the fan blade, and sealing a gap between the plug and the opening using a fibre laser. In certain embodiments, the method includes forming the blade into a specified contour with a laser deposition operation, removing a blowpipe, removing an excess plug portion with a machine tool, positioning a shim between the plug and the at least one edge of the opening, and/or forming the opening with a machine tool. In certain embodiments, evacuating at least a portion of a gas in an enclosure defining the blade includes introducing a substantial vacuum in the enclosure, and holding the substantial vacuum for about 10 minutes prior to the sealing a gap between the plug and the at least one edge of the opening. 
     In certain embodiments, the blade includes three material sheets, and the method further includes machining a slot in the blade wherein a bottom face of the slot intersects the opening. In certain embodiments, at least one side face of the slot comprises a beveled face, and in certain embodiments the beveled face is about 45 degrees. In certain embodiments, the bottom face of the slot is at least about 0.01 inches lower than a blowpipe, and/or the bottom face of the slot is flat. In certain embodiments, the slot is formed from material removed from only two of the three material sheets. In certain embodiments, the material sheets comprise one of titanium and a titanium alloy. In certain embodiments, the plug is sized to form a gap of at least 0.002 inches between the plug and at least one edge of the opening. In certain embodiments, the shim comprises a width of about 0.02 inches. In certain embodiments, the plug is positioned in a blowpipe remainder. 
     One exemplary embodiment is a system including a vacuum box enclosing a blade, the blade including a hollow portion and an opening to the hollow portion, a laser deposition device positioned at a distance from the opening, wherein the distance from the opening is not greater than a focal length of the laser deposition device, and a plug structured to leave at least a 0.002″ gap between the plug and at least one edge of the opening when the plug is received in the opening. In a further embodiment, the vacuum box includes a window interposed between the opening and the laser deposition device; 
     In certain embodiments, the system further includes the laser deposition device structured to form the blade into a specified contour, the blade including one of titanium and a titanium alloy, the vacuum pump having a vacuum capability of less than about 0.001 μmHg, and/or a machine tool structured to form a slot centered over a membrane “D-shaped” cutout. In certain embodiments, the blade includes three layered material sheets, wherein the slot is formed in only two of the three layered material sheets. In certain embodiments, the plug rests on the D-shaped cutout when the plug is received in the opening. In certain embodiments, shim(s) are positioned between the plug and the at least one opening. 
     While the invention has been described in connection with specific embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass any modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while any characterization of a feature in the description above indicates that feature so described may desirable or present in certain embodiments, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.