Abstract:
A method of repairing a circumferential flanged ring of a gas turbine engine with a bushing includes the steps of removing a damaged portion from a flange of a circumferential flanged ring that has an original profile to define a new profile and removing a portion of a bushing to define a bushing profile that matches the new profile of the flange. The method further includes the step of attaching the bushing to the flange of the circumferential flanged ring.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates generally to a bushing used to restore, repair and create a circumferential flanged ring. 
         [0002]    Gas turbine engines include multiple sections, such as a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. Bearing compartments include bearings, etc., that rotatably support and rotatably couple the components in many of these sections. The gas turbine engine also includes several components that are a circumferential flanged ring. 
         [0003]    One example circumferential flanged ring is a static low pressure compressor bearing support. The static low pressure compressor bearing support includes an end with a smaller circumference including a flange that is attached to a static front bearing support assembly, and an opposing end with a larger circumference including a flange that is attached to a static strut. 
         [0004]    The circumferential flanged ring can be damaged due to cracking. This type of damage can be repaired by welding, plate welding, or plasma welding. However, welding can cause distortion. The circumferential flanged ring can also be damaged due to dimensional changes caused by creep, thermal stresses or aging. If this occurs, bolt holes in the flange could misalign with a corresponding component during assembly, making the attachment of the circumferential flanged ring to another component more difficult. 
         [0005]    The current practice for a non-serviceable flange made of titanium, steel, cobalt or nickel is to cut off and weld a replacement forging with extra stock to allow machining of the original flange geometry. Certain types of alloys, such as aluminum and magnesium, cannot be easily processed by the welded flange replacement process and cannot be repaired by this method. 
       SUMMARY OF THE INVENTION 
       [0006]    A method of repairing a circumferential flanged ring of a gas turbine engine with a bushing includes the steps of removing a damaged portion from a flange of a circumferential flanged ring that has an original profile to define a new profile and removing a portion of a bushing to define a bushing profile that matches the new profile of the flange. The method further includes the step of attaching the bushing to the flange of the circumferential flanged ring. 
         [0007]    A bushing and circumferential flanged ring assembly of a gas turbine engine includes a circumferential flanged ring and a bushing. The circumferential flanged ring includes a flange having an original profile, and a portion is removed to define a new profile. The bushing has a bushing profile that matches the new profile of the flange. The flange and the bushing are attached. 
         [0008]    A bushing and circumferential ring assembly of a gas turbine engine includes a plurality of segments attached to form a circumferential ring, the circumferential ring having a first end and an opposing second end. The bushing and circumferential ring assembly also includes a circumferential bushing fitted on each of the first end and the second end of the circumferential ring. 
         [0009]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates a simplified cross-sectional view of a standard gas turbine engine; 
           [0011]      FIG. 2  illustrates a cross-sectional view of a portion of a circumferential flanged ring; 
           [0012]      FIG. 3  illustrates a cross-sectional view of a portion of a circumferential flange of the circumferential flanged ring including a damaged portion; 
           [0013]      FIG. 4  illustrates a cross-sectional view of a portion of the flange of the circumferential flanged ring after machining to remove the damaged portion; 
           [0014]      FIG. 5  illustrates a cross-sectional view of a portion of a circumferential bushing employed to repair the circumferential flanged ring; 
           [0015]      FIG. 6  illustrates a cross-sectional view of the bushing positioned on the circumferential flanged ring; 
           [0016]      FIG. 7  illustrates a cross-sectional view of the bushing positioned on the circumferential flanged ring including a longer tab; and 
           [0017]      FIG. 8  illustrates a end view of a circumferential ring assembly formed of several segments; 
           [0018]      FIG. 9  illustrates one example of a joint between adjacent segments of the circumferential ring assembly formed of several segments; 
           [0019]      FIG. 10  illustrates another example of a joint between adjacent segments of the circumferential ring assembly; 
           [0020]      FIG. 11  illustrates a schematic circumferential ring assembly including two bushings at opposing ends to provide hoop strength: 
           [0021]      FIG. 12  illustrates a circumferential ring assembly with a flanged bushing at opposing ends of the circumferential ring; and 
           [0022]      FIG. 13  illustrates a circumferential flanged ring assembly with a flanged bushing at opposing ends of the circumferential ring. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]      FIG. 1  illustrates a gas turbine engine  10  that is circumferentially disposed about an axis  12 . The gas turbine engine  10  includes a fan section  14 , a low-pressure compressor section  16 , a high-pressure compressor section  18 , a combustion section  20 , a high-pressure turbine section  22 , and a low-pressure turbine section  24 . 
         [0024]    During operation, air is compressed in the low-pressure compressor section  16  and the high-pressure compressor section  18 . The compressed air is then mixed with fuel and burned in the combustion section  20 . The products of combustion are expanded across the high-pressure turbine section  22  and the low-pressure turbine section  24 . 
         [0025]    The high-pressure compressor section  18  and the low-pressure compressor section  16  include rotors  26  and  28 , respectively. The rotors  26  and  28  are configured to rotate about the axis  12 , driving the compressors  16  and  18 . The compressors  16  and  18  include alternating rows of rotating compressor blades  30  and static airfoils or vanes  32 . 
         [0026]    The high-pressure turbine section  22  includes a rotor  34  that is rotatably coupled to the rotor  26 , and the low-pressure turbine section  24  includes a rotor  36  that is rotatably coupled to the rotor  28 . The rotors  34  and  36  are configured to rotate about the axis  12  in response to expansion. When rotated, the rotors  34  and  36  drive the high-pressure compressor section  18  and the low-pressure compressor section  16 . The rotor  36  also rotatably drives a fan  38  of the fan section  14 . The turbines  22  and  24  include alternating rows of rotating airfoils or turbine blades  40  and static airfoils or vanes  42 . 
         [0027]    As shown in  FIG. 2 , the gas turbine engine  10  includes a circumferential flanged ring  44 . The circumferential flanged ring  44  can be any component of the gas turbine engine  10  that is a bearing support, a case, or a flanged ring that has adequate space or clearance on at least one side to allow for the connection and engagement of a bushing  72 , as described below. The combination of the bushing  72  and the circumferential flanged ring  44  support the structural requirements of the original undamaged circumferential flanged ring  44 . 
         [0028]    The circumferential flanged ring  44  can have the shape of a truncated cone, a cylinder, or be frustoconical in shape (although only a cross-section of a portion of the circumferential flanged ring  44  is shown). In the example show, the circumferential flanged ring  44  has the shape of a truncated cone. The circumferential flanged ring  44  is static. In one example, a first end  46  of the circumferential flanged ring  44  includes a flange  48  having a plurality of bolt holes  50 . The flange  48  is circumferential in shape, and the plurality of bolt holes  50  are arranged in a circular pattern. An opposing second end  52  of the circumferential flanged ring  44  includes another flange  54  (also circumferential in shape) that includes a plurality of bolt holes  56 , and the plurality of bolt holes  56  are also arranged in a circular pattern. The flange  48  has a smaller diameter than the diameter of the another flange  54 . A body portion  58  having the shape of truncated cone is defined between the flange  48  and the another flange  54 . 
         [0029]    The flange  48  is connected to a static assembly  60  (shown schematically in  FIGS. 1 and 2 ) that includes a plurality of bolt holes  62  that each align with one of the plurality of bolt holes  50 , and a bolt  64  is received in each set of the aligned bolt holes  50  and  62 . The second end  52  is connected to another static assembly  65  (shown schematically in  FIGS. 1 and 2 ) including a plurality of bolt holes  66  that each align with one of the plurality of bolt holes  56 , and a bolt  68  is received in each set of the aligned bolt holes  56  and  66 . 
         [0030]    In the example shown in  FIG. 2 , the circumferential flanged ring  44  is a low pressure compressor bearing support. The static assembly  60  is a static front bearing support assembly, and the another static assembly  65  is a static strut. The static front bearing support assembly supports a rotating bearing  108  associated with a rotating shaft  110  of the gas turbine engine  10 . Although  FIG. 2  illustrates the circumferential flanged ring  44  as a low pressure compressor bearing support, the circumferential flanged ring  44  can be any component of the gas turbine engine  10  that is a bearing support, a case, or a flanged ring that has adequate space on at least one side to allow for the connection of a bushing  72 , as described below. 
         [0031]      FIG. 3  shows a cross-sectional view of a portion of the flange  48 . Portions of the flange  48  are prone to damage. An outer surface of the flange  48  defines an original outer profile  70 . A bushing  72  that is circumferential in shape (a cross-section of a portion of the bushing  72  is shown in  FIG. 5 ) is employed to repair a damaged area  74  of the flange  48 . In one example, the flange  48  can crack (which is likely to occur on an inner portion of the flange  48 ), for example from handling damage, and the axial planes need to be restored. In another example, an area of the flange  48  needs to be dimensionally restored (which is likely to occur on a face of the flange  48 ) because of dimensional changes due to creep caused by thermal stresses and/or aging. 
         [0032]      FIG. 4  illustrates a cross-sectional view of a portion of the flange  48  after machining. The original outer profile  70  of the flange  48  is shown in dashed lines. The flange  48  is machined to remove the damaged area  74  or any area that needs to be dimensionally restored to define a new outer profile  76 , shown in solid lines. 
         [0033]    In one example, the flange  48  is also milled or machined to radially elongate the bolt holes  50  such that each bolt hole  50  has an oval shape and defines a new bolt hole profile  78 . In one example, at least one recess  80  is formed on a top surface  82  of the flange  48 . In one example, a seal groove  84  can be formed on an outer surface  86  of the flange  48 . In one example, the recess  80  and the groove  84  are machined. 
         [0034]      FIG. 5  illustrates the bushing  72  that is to be attached to the new outer profile  76  of the flange  48 . In one example, the bushing  72  is machined. The outer profile  104  of the bushing  72  is shown in solid lines. In one example, the bushing  72  is made of the same material as the circumferential flanged ring  44 , including the flange  48 . For example, both the bushing  72  and the circumferential flanged ring  44  are made of an aluminum alloy or a magnesium alloy. The bushing  72  and the circumferential flanged ring  44  can also be made of low alloy steel, titanium, nickel, or any other material. The bushing  72  and the circumferential flanged ring  44  can also be made from different materials. The matching of thermal expansion must be managed if an alternate material is selected for strength, corrosion resistance or any other reason. The bushing  72  is machined such that an inner profile  88  of the bushing  72  matches and corresponds to the new outer profile  76  of the flange  48 . 
         [0035]    In one example, the bushing  72  includes at least one tab  90  that corresponds in size, shape and location to the at least one recess  80  of the flange  48 . The at least one recess  80  and the at least one tab  90  lock the bushing  72  to the flange  48  for the purpose of resisting rotational motion between the bushing  72  and flange  48 . The bushing  72  and the flange  48  can include a plurality of tabs  90  and a plurality of recesses  80 , respectively. The number of recesses  80  equals the number of tabs  90 , and the recesses  80  and the tabs  90  are located to align with each other when the bushing  72  is positioned on the flange  48 . In one example, there are two recesses  80  and two tabs  90 . 
         [0036]    A seal groove  92  that corresponds in axial and radial placement and size to the seal groove  84  of the flange  48  can also formed on an inner surface  102  of the bushing  72 . In one example, the seal groove  84  is machined. 
         [0037]    The bushing  72  includes a plurality of bolt holes  94  that each align with one of the plurality of bolt holes  50  of the flange  48  (which can now have the new bolt hole profile  78 ) when the bushing  72  is assembled on the flange  48 . In one example, the bolt holes  94  are circular. Each of the plurality of bolt holes  94  have a diameter equal to the original diameter of each of the plurality of bolt holes  50  prior to being radially elongated to have the new bolt hole profile  78 . The bushing  72  will locate the bolt holes  50  radially. Both the flange  48  and bushing  72  will concurrently locate the holes  50  and  94  circumferentially. 
         [0038]    As shown in  FIG. 6 , the bushing  72  is then positioned on the flange  48  of the circumferential flanged ring  44 . If the bushing  72  and the circumferential flanged ring  44  includes the at least one tab  90  and the at least one recess  80 , respectively, the at least one tab  90  of the bushing  72  is received in the at least one recess  80  of the flange  48  and increases the hoop stiffness of the bushing  72  relative to the flange  48  and provides clocking. An outer diameter defined by the at least one tab  90  is greater than an outer diameter defined by a remainder of the bushing  72  to provide the hoop stiffness. An outer diameter defined by the at least one recess  80  of the flange  48  is slightly larger than an inner diameter defined by the at least one tab  90  of the bushing  72 , creating a tight interference that retains the flange  48  and the bushing  72  together in this embodiment. The new outer profile  76  of the flange  48  contacts the inner profile  88  of the bushing  72  as the profiles  76  and  88  have been machined to match each other. 
         [0039]    If the flange  48  and the bushing  72  include seal grooves  84  and  92 , respectively, a seal  96 , for example an o-ring, is located in the aligned seal grooves  84  and  92 . The seal  96  prevents the bypass of oil and/or air. As bushing  72  is much larger in size than traditional bushings, there is room for installing the seal  96  between the flange  48  and the bushing  72  to prevent fluid or air leakage. 
         [0040]    Again, as the bushing  72  is much larger in size than traditional bushings, there is room for a sealing compound at the interface between the flange  48  and bushing  72 . In another example, instead of seal grooves  84  and  92 , the bushing  72  and the flange  48  can be coated with a fluoroelastomer sealant to prevent the bypass of oil and/or air. Alternately, instead of seal grooves  84  and  92 , an adhesive agent or anaerobic sealing compound can be employed to bond the bushing  72  and the flange  48  to prevent the bypass of oil and/or air. In one example, the adhesive agent is Loctite®, a registered trademark of Henkel Corporation of Rocky Hill, Conn. The bushing  72  and the flange  48  are then clamped together until the fluoroelastomer sealant or the adhesive agent are cured. 
         [0041]    Once assembled, the engagement of the at least one tab  90  of the bushing  72  in the at least one recess  80  of the flange  48  provide a strong attachment between the bushing  72  and the flange  48 . In one example, the outer profile  104  of the bushing  72  can be machined to correspond to the original outer profile  70  of the flange  48  and have a new outer profile  106  that matches the original outer profile  70  of the flange  48 . The at least one tab  90  and the bonding material, if any, retain the bushing  72  to the flange  48  of the circumferential flanged ring  44  to prevent separation during assembly and use. By employing the bushing  72 , the hoop stiffness is increased. 
         [0042]    Each of plurality of bolt holes  94  of the bushing  72  are aligned with one of the plurality of bolt holes  50  (in one example, the plurality of bolt holes  50  have the new bolt hole profile  78 ) of the flange  48 . The bolt  64  is received in each of the aligned bolt holes  50  and  94  (as well as the bolt hole  62  of the static assembly  60 ). In the example where the bolt holes  50  are slightly radially elongated, this allows for an easier assembly and installation of the bolts  64  due to the additional clearance  100  created by the radially elongated bolt holes  50  having the new bolt hole profile  78 . Once assembled, the secured parts together carry load in all directions, except for the direction in which the plurality of bolt holes  50  are radially elongated. 
         [0043]    In another example, the bushing  72  can be attached to an inner diameter of the flange  48 . In this example, there is clearance for the bushing  72  inside the inner diameter of the circumferential flanged ring  44 . 
         [0044]    In another example shown in  FIG. 7 , the at least one tab  90  of the bushing  72  has a length that covers an outer diameter of the flange  48 . This additional length provides the bushing  72  with anti-rotational features relative to the flange  48 . 
         [0045]    In another example, the circumferential flanged ring  44  and the bushing  72  do not include the at least one recess  80  and the at least one tab  90 , respectively. In this example, the circumferential flanged ring  44  and the bushing  72  are aligned by the bolts  64  received in the bolt holes  50  and  94  of the circumferential flanged ring  44  and the bushing  72 , respectively. 
         [0046]    In another example, as shown in  FIG. 8 , a circumferential ring assembly  114  has a shape that is not possible to achieve by casting in a single process. Therefore, individual separate segments  116 ,  118 ,  120  and  122  are cast and assembled together to form the circumferential ring assembly  114 . Although four separate segments  116 ,  118 ,  120  and  122  are illustrated and shown, the circumferential ring assembly  114  can include any number of separate segments. 
         [0047]    As shown in  FIGS. 9 and 10 , the separate segments  116 ,  118 ,  120  and  122  are secured together by interlocking overlapping joints. In one example shown in  FIG. 9 , one segment  116  includes a plurality of protrusions  134  and a plurality of recesses  136  that extend within the material of the segment  116 . The other segment  118  includes a plurality of protrusions  138  each located to be received in one of the plurality of recesses  136  and a plurality of recesses  140  each located to receive one of the plurality of protrusions  134 . The protrusions  134  and  138  are each received in one of the recesses  140  and  136 , respectively, to retain the segments  116  and  118  together. The other segments  120  and  122  are retained in a similar manner. 
         [0048]    In another example shown in  FIG. 10 , the segment  116  includes a projection  164  and a recess  144 , and the segment  118  includes a projection  166  and a recess  168 . The projection  164  of the segment  116  is received in the recess  168  of the segment  118 , and the projection  166  of the segment is received in the recess  144  of the segment  118 . The other segments  120  and  122  are retained in a similar manner. 
         [0049]    Although the assembly of the segments  116 ,  118 ,  120  and  122  creates a circumferential ring assembly  114 , the interlocking joints do not provide stiffness, and the segments  116 ,  118 ,  120  and  122  can wobble. As shown schematically in  FIG. 11 , circumferential bushings  128  and  130  are be added to both the ends of the circumferential ring assembly  114  to provide hoop stiffness and strength to the plurality of separate segments  116 ,  118 ,  120  and  122  that are assembled to form the circumferential ring assembly  114 . A flange of each of the circumferential ring assembly  114  and the circumferential bushings  128  and  130  are machined and assembled as described above and push outward against the circumferential ring assembly  114 . 
         [0050]      FIG. 12  illustrates an example segmental circumferential ring assembly  142 . Circumferential bushings  132  and  174  have a substantial L-cross section including a portion  158  the contacts the circumferential ring assembly  142  and a substantially perpendicular flange  160  (shown in cross-section). The portion  158  of each of the circumferential bushings  132  and  174  are attached at the ends of the circumferential ring assembly  142 . In one example, the circumferential bushings  132  and  174  are secured by an interference fit with the circumferential ring assembly  142 . Additionally, fasteners  162 , for example bolts, can be used to attach the portion  158  to the circumferential ring assembly  142 . 
         [0051]      FIG. 13  illustrates another example segmental circumferential ring assembly  176  including a circumferential flange  146  and  148  at each of the opposing ends of the circumferential ring assembly  176 . A circumferential bushing  150  and  152  (shown in cross-section) is attached to each of the circumferential flanges  146  and  148 , respectively, and each have a substantial L-cross section. Each circumferential bushing  150  and  152  includes a portion  154  the contacts the outermost portion of the circumferential flanges  146  and  148  and a perpendicular portion  170  flush and parallel with the circumferential flanges  146  and  148 . In one example, the circumferential bushings  150  and  152  are secured by an interference fit with the flanges  146  and  148 , respectively, of the circumferential ring assembly  176 . 
         [0052]    The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.