Abstract:
A fastener system for connecting a first member to a second-member is described. The fastener system includes a flexible shell having therein a flexible reinforcement member in the form of a frame. The shell and frame can be placed through holes in the two members and filled with a filler material that hardens to form a rigid fastener in order to connect the first and second members together. The fastener system and method can be used even when the holes in the two members are misaligned or are of different sizes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of the priority of U.S. Provisional Application for Patent No. 60/537,556, filed on Jan. 20, 2004, the entire disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]     The present disclosure relates to a fastener assembly, system and method adapted to connect a first member to a second member, and in particular to a fastener having a hollow shell adapted to be inserted through an aperture and that is adapted to be subsequently filled with a filler material, such that the shell and filler material conform to and fill the apertures to create a connection between the first and second members.  
         [0003]     By way of example but not limitation, in the construction of aircraft, such as airplanes and helicopters, and of other products, a first member having a first aperture is often required to be attached to a second member having a second aperture. Rigid metallic fasteners such as rivets and bolts have often been used to connect a first member to a second member. Rigid metallic fasteners do not compensate for misalignment of the aperture in the first member with the second aperture in the second member. In addition, when metallic fasteners are used in connection with aircraft and other products that are intended to avoid detection by electronic detection devices such as radar, the metallic fasteners may provide a detectable radar signature, although other components of the aircraft or other product may be made from materials that absorb radar emissions or that provide minimal radar detection.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0004]      FIG. 1  is a cross sectional view of an embodiment of the disclosed fastener assembly shown connecting a first member to a second member.  
         [0005]      FIG. 2  is a cross sectional view of the first member and of the second member shown with their respective apertures in misalignment.  
         [0006]      FIG. 3  is a perspective view of the disclosed fastener assembly removed from the misaligned members shown with the shank of the fastener in a misaligned position.  
         [0007]      FIG. 4  is a cross sectional view of the envelope or shell of the fastener shown in  FIG. 3 .  
         [0008]      FIG. 5  is a side elevational view of the frame, matrix or reinforcement member of the fastener.  
         [0009]      FIG. 6  is a cross sectional view of the fastener extending through a first member and a second member and shown with an injection device for filling the fastener with a filler material. 
     
    
     DETAILED DESCRIPTION  
       [0010]     A fastener assembly  20  as shown in the drawing figures is adapted to attach or connect a first member  22  to a second member  24 . The first member  22  includes a first surface  26  and a spaced apart second surface  28 . The first member  22  includes an aperture  30  that extends through the first member  22  from the first surface  26  to the second surface  28 . The aperture  30  forms a generally cylindrical peripheral side wall  32  having a generally circular peripheral first edge  34  located at the first surface  26  and a generally circular peripheral second edge  36  located at the second surface  28 . The aperture  30  includes a linear central axis  38 . The second member  24  includes a first surface  46  and a spaced apart second surface  48 ; The first surface  46  of the second member  24  is adapted to engage the second surface  28  of the first member  22 . The second member  24  includes an aperture  50  that extends from the first surface  46  to the second surface  48 . The aperture  50  includes a generally cylindrical peripheral side wall  52 . The side wall  52  includes a generally circular peripheral first edge  54  located at the first surface  46  and a generally circular peripheral second edge  56  located at the second surface  48 . The aperture  50  includes a generally linear central axis  58 .  
         [0011]     The first member  22  and second member  24  are intended to be broadly interpreted and may include, but are not limited to, a plate, panel, wall, bracket or other structure or shape. The surfaces  26 ,  28 ,  46  and  48  may be generally planar or curved. The first and second members  22  and  24  may be formed from non-metallic materials such as composite materials. If desired, the first and second members  22  and  24  may also be made from metallic materials such as steel, stainless steel, aluminum, titanium and the like. Each aperture  30  and  50  may be generally circular or cylindrical as shown in  FIGS. 1 and 2 . Each aperture  30  and  50  may also be formed in other configurations such as square, hexagonal and other polygonal shapes, or as elongate slots. In addition, one of the apertures  30  or  50  may be larger in size or diameter than the other aperture. The first and second apertures  30  and  50  may be aligned with one another as shown in  FIG. 6 , wherein the central axis  38  of the aperture  30  and the central axis  58  of the aperture  50  are coaxial with one another. As shown in  FIGS. 1 and 2 , the apertures  30  and  50  may be offset or misaligned with one another such that their respective central axes  38  and  58  are not coaxial with one another and are spaced apart from one another. The apertures  30 ,  50  may also be in the form of other shapes and contours whether intentionally designed or unintentionally occurring. For example, with regard to intentional configurations, it is envisioned that configurations may be employed which provide increased holding strength such as intentional offsets, threads, other engaging structures including recesses and extensions. As it will be described in greater detail below, it is envisioned that other configurations may be employed to increase the holding strength to the fastener assembly  20  in the apertures.  
         [0012]     As shown in  FIG. 4 , the fastener assembly  20  includes an envelope or shell  70  having a generally hollow configuration. One embodiment of the shell is formed from a generally non-metallic flexible and resilient material. The shell  70  may be formed from an elastomeric material such as urethane. It is envisioned that a variety of materials may be used for the shell including but not limited to metallic, partially metallic, partially rigid as well as memory materials and metals. Reference to particular materials for the shell is provided for purpose of example only and should be broadly interpreted to contemplate any suitable material which can be used with the fastener assembly  20 .  
         [0013]     As shown in  FIG. 1 , the shell  70  includes a first head  72 , a second head  74  and a shank  76  that extends between the first head  72  and the second head  74 . The shell  70  includes a hollow chamber  78  and a central longitudinal axis  80 . The first head  72  is located at a first end of the fastener  20  and the second head  74  is located at a second end of the fastener  20 . It is envisioned that while the heads  72 ,  74  may be embodied in different shapes, for example, but not by way of limitation, enlargements in the shell  70 . Additionally, it is envisioned that in some situations only a single head may be used or no head at all with the shell forming a generally continuous body with little or no enlargement providing a head. As such, it is envisioned that the interpretations of the fastener assembly  20  be broadly construed.  
         [0014]     In the embodiment shown in the Figures, the first head  72  of the shell  70  includes a generally circular flange  82  having a generally planar and annular first wall  84 , and a generally planar and annular second wall  86  that is spaced apart and generally parallel to the annular first wall  84 . The annular walls  84  and  86  are located generally concentrically about the central axis  80 . The first head  72  includes a generally cylindrical peripheral side wall  88  that extends generally concentrically about the central axis  80  and that extends between the outer circular edges of the first and second annular walls  84  and  86 . The flange  82  includes a hollow flange cavity  90  that forms a portion of the chamber  78 . The first head  72  also includes a cap  92  that is attached to the inner circular edge of the annular second wall  86  of the flange  82 . The cap  92  includes a generally planar and circular end wall  94  that is located generally concentrically about and perpendicular to the central axis  80  and that is spaced apart from and generally parallel to the annular second wall  86  of the flange  82 . The cap  92  includes an inclined conical shaped peripheral side wall  96  that extends between the inner circular edge of the annular second wall  86  of the flange  82  and the circular peripheral edge of the end wall  94 . The end wall  94  includes a central aperture  98  that is located along the axis  80  and that is in fluid communication with the chamber  78 . The cap  92  includes a hollow cap cavity  100  that forms a portion of the chamber  78 .  
         [0015]     The second head  74  of the shell  70  includes a generally circular flange  110  having a generally planar and annular first wall  112  and a generally planar and annular second wall  114  that is spaced apart from and generally parallel to the annular first wall  112 . The annular walls  112  and  114  are located generally concentrically about and perpendicular to the central axis  80 . The second head  74  includes a generally cylindrical peripheral side wall  116  that extends generally concentrically about the central axis  80  and that extends between the outer circular edges of the first and second annular walls  112  and  114 . The flange  110  includes a hollow flange cavity  118  that forms a portion of the chamber  78 . The second head  74  also includes a cap  120  that is attached to the inner circular edge of the annular second wall  114  of the flange  110 . The cap  120  includes a generally planar and circular-end wall  122  that is located generally concentrically about and perpendicular to the central axis  80  and that is spaced apart from and generally parallel to the annular second wall  114  of the flange  110 . The cap  120  also includes an inclined conical shaped peripheral side wall  124  that extends between the inner circular edge of the annular second wall  114  of the flange  110  and the circular peripheral edge of the end wall  122 . The cap  120  includes a hollow cap cavity  126  that forms a portion of the chamber  78 .  
         [0016]     The shank  76  of the shell  70  includes a first end  132  attached to the inner peripheral edge of the annular first wall  84  of the first head  72 , and a second end  134  attached to the inner peripheral edge of the annular first wall  112  of the second head  74 . The shank  76  includes a generally cylindrical peripheral side wall  136  that extends generally concentrically about the axis  80 . The side wall  136  includes an internal surface  138  and an external surface  140 . The side wall  136  includes a plurality of apertures  142  that are located along the length of the shank  76  between the first end  132  and the second end  134 . The shank  76  includes a hollow shank cavity  144  that forms a portion of the chamber  78 . It should be noted that while the shank  76  as shown in  FIGS. 3 and 4  includes an upper portion that is offset from a lower portion,  FIGS. 3 and 4  show the shank  76  in this deformed position to illustrate how the shank would be deformed and misaligned when the apertures  30  and  50  in the members  22  and  24  are misaligned as shown in  FIGS. 1 and 2 . Prior to insertion into the apertures  30  and  50  of the first and second members  22  and  24 , the shank  76  may have a uniform configuration along the axis  80  between the first end  132  and second end  134 .  
         [0017]     The fastener assembly  20  as shown also includes a reinforcement member in the form of a frame or matrix  150 . As shown in  FIGS. 1 and 6 , the reinforcement member  150  is located within the chamber  78  of the shell  70  and is attached to the shell  70 . The reinforcement member  150  includes an elongate generally cylindrical column  152  that extends along the central axis  80  between a first end  154  and a second end  156 . The column  152  is adapted to be located within the shank cavity  144  of the shell  70 . The outer periphery of the column  152  is attached to and embedded within the shank  76  of the shell  70 . The reinforcement member  150  also includes one or more first generally disc-shaped members  158  attached to the first end  154  of the column  152 . The disc-shaped members  158  are generally concentrically located on the axis  80  and extend generally radially outwardly perpendicular to the axis  80  to an outer generally circular edge  160 . The reinforcement member  150  also includes one or more second generally disc-shaped members  162 . Each second disc-shaped member  162  is located generally concentrically about the central axis  80  and extends radially outwardly generally perpendicular thereto to a generally circular edge  164 . The first disc-shaped members  158  have a larger diameter than the second disc-shaped members  162 . The first disc-shaped members  158  are adapted to be located within the flange cavity  90  of the flange  82 . The second disc-shaped members  162  are adapted to be located within the cap cavity  100  of the cap  92 . Although not shown in  FIG. 5 , the reinforcement member  150  may include one or more first disc-shaped members at the second end  156  of the column  152  that are adapted to be located within the flange cavity  118  of the flange  110 , and one or more second disc-shaped members at the second end  156  of the column  152  that are adapted to be located within the cap cavity  126  of the cap  120 .  
         [0018]     The reinforcement member  150  is formed as a three-dimensional mesh, frame, lattice or matrix of fiber-like elements or threads. The threads may be formed from any suitable material including, but not limited to plastics, composites, as well as, non-metallic materials such as, for example, but not limited to glass, carbon, aramid, graphite and the like. In the embodiment as shown, the interweaving of the threads in the three dimensional matrix creates a plurality of hollow voids within the reinforcement member  150 . The fibers that form the reinforcement member  150  are flexible such that the reinforcement member  150  itself is flexible.  
         [0019]     The frame or reinforcement member  150  can take many different forms. For example, the frame  150  can be a flexible structure which is integrally formed as a single piece unit. The single piece unit can be provided in the shell  170  or may be inserted into the shell  170  after the shell is placed in a desired position in the work piece. Alternatively, the reinforcement member  150  can be provided in multiple pieces such that a first portion or disc-shaped member  158  is positioned in the shell  70  with the second generally disc-shaped member  162  carried on the column  152 . This configuration might allow the shell  70  to be inserted through the openings yet retained on the one end by the disc-shaped member  162  retained in the shell  70 . Subsequent attachment of the column and first disc-shaped member is achieved prior to final forming of the fastener assembly.  
         [0020]     If desired, the flange cavity  118  of the flange  110  and the cap cavity  126  of the cap  120 , may be filled with a non-metallic hardened filler material that forms a non-metallic plug, with the second end  156  of the reinforcement member  150  embedded in the plug, prior to inserting the fastener  20  into the apertures  30  and  50  of the members  22  and  24 . The plug is adapted to provide a rigid member that can be pressed into engagement with the second surface  26  of the first member  22 .  
         [0021]     In operation, the first surface  46  of the second member  24  is placed in engagement with the second surface  28  of the first member  22  such that the aperture  50  of the second member  24  is in communication with the aperture  30  in the first member  22 . The apertures  30  and  50  are preferably aligned with one another such that the respective axes  38  and  58  are coaxial with one another. However, as shown in  FIGS. 1 and 2 , the apertures  30  and  50  may be misaligned with one another.  
         [0022]     The first head  72  of the shell  70  is flexibly collapsed and is inserted through the aperture  30  in the first member  22  and aperture  50  in the second member  24  until the flange  110  of the second head  74  engages the first surface  28  of the first member  22 . The first head  72  expands after it exits the aperture  50  such that the flange  82  of the first head  72  engages the second surface  48  of the second member  24 . The first member  22  and the second member  24  are then forcibly pressed into compressed engagement with one another.  
         [0023]     An injection device  170  is then placed into engagement with the flange  182  of the first head  72  and is placed in communication with the aperture  98  in the cap  92  of the first head  72 . The injection device  170  injects a non-metallic liquid filler material  172  through the aperture  98  in the cap  92  and into the chamber  78  of the shell  70 . As the filler material  172  is injected into the chamber  78 , air within the chamber  78  is vented out of the shell  70  through the apertures  142  in the shell  70 . The liquid filler material  172  is injected into the chamber  78  until all of the voids within the reinforcement member  150  are filled, and the chamber  78  of the shell  70  is filled with the filler material  172 . Thereafter, the filler material  172  sets and hardens and becomes a non-metallic rigid filler material. As the filler material  172  is injected into the chamber  78 , the filler material  172  will deform the configuration of the reinforcement member  150  and shell  70  such that the shell  70  will completely fill the apertures  30  and  50  of the first and second members  22  and  24 . The filler material  172  may comprise a resin material, such as an epoxy or vinyl ester.  
         [0024]     The flexible shell  70  and the flexible reinforcement member  150  are adapted to deform and completely fill the apertures  30  and  50  of the first and second members  22  and  24 , even if the apertures are misaligned with one another. The shell  70  has the ability to adapt to fill any configuration of an aperture in a balloon-like manner, wherein the shell  70  is adapted to conform to the shape of the surface that forms the aperture, such as the sidewalls  32  and  52 . The three-dimensional matrix of fibers in the reinforcement member  150  extend in the X, Y, and Z directions in a three-dimensional coordinate system and provide the fastener  20  with strength in both shear and tension. The materials from which the shell  70 , reinforcement member  150 , and filler material  172  are formed can be selected to match the material properties of the first member  22  and second member  24 , to provide stable dimensional properties and lower stresses in the connected assembly of the members  22  and  24  that would otherwise result due to the effect of temperature changes and thermal expansion. The fastener  20  may be made entirely from non-metallic material, such that the fastener  20  produces a very low or no radar reflection.  
         [0025]     Various features of the invention have been particularly shown and described in connection with the illustrated embodiment of the invention, however, it must be understood that these particular arrangements merely illustrate the principles of the invention, and that the invention is to be given its fullest breadth within the terms of the appended claims.