Abstract:
An electrical connector for a composite core conductor and a method of controlling crimping thereof includes a coupling portion and a tubular portion extending from the coupling portion. A conductor has a non-metallic core surrounded by electrically conductive strands and has a connecting portion of the core extending axially beyond the strands. The connecting portion is received in the tubular portion. A crimped portion on the tubular portion radially engages the connecting portion and secures the conductor to the tubular portion. The crimped portion is formed by concave surfaces on internal surfaces of crimping dies. The concave surfaces have different radii of curvature than remaining portions of the internal surfaces.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/800,255, filed Mar. 15, 2013, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to electrically connecting a composite core conductor. More particularly, the present invention relates to a crimp die for connecting a composite core of a conductor to an electrical connector. Still more particularly, the present invention relates to a method of connecting a composite core of a conductor to an electrical connector. 
       BACKGROUND OF THE INVENTION 
       [0003]    The vast majority of high voltage transmission conductors used includes strands of high strength steel surrounded by multiple strands of aluminum wire. The steel strands are the principle load bearing component holding up the wire, while the softer, more elastic aluminum strands include the majority of the electrical power transport component. Many variations of transmission wire operating at between approximately 115 kv to 800 kV involve this basic design concept and have these two basic components. 
         [0004]    More recently, a composite core conductor having a fiberglass and epoxy resin core covered by aluminum wire has emerged as a substitute for the steel support stranding in high voltage transmission conductors. However, the outer surface of the composite core is difficult to mechanically connect to a compression tube of a connector member. The outer surface of the composite core is sensitive, such that a scratch on the outer surface can lead to a fracture of the composite core. Due to the sensitivity of the composite core, composite core conductors are not crimped and are usually connected with wedge connectors such as is disclosed in U.S. Pat. No. 7,858,882 to De France, which is hereby incorporated by reference in its entirety. Accordingly, a need exists for an electrical connector in which a composite core conductor is crimped thereto without damaging the outer surface of the composite core. 
         [0005]    A conventional crimp die  2  is shown in  FIGS. 1-3 . A plurality of planar surfaces  3  form a crimp surface of the die  2 . For example, the crimp surface of each conventional die  2  is comprised of three planar surfaces  3 , as shown in  FIG. 3 . The planar surfaces  3  form a substantially hexagonal crimping area during the crimping process and result in a gap  4  between the dies  2  and a tubular portion  5  in which the composite core  26  is disposed, as shown in  FIG. 2 . The resulting gap  4  can detrimentally affect the outer surface of the composite core  26  as the crimp is not completely controlled. Additionally, the planar surfaces  3  provide a smaller area of compression  65  between the planar crimp surfaces  3  and the outer surface of the tubular portion  5  in which the composite core  26  is disposed. Furthermore, the planar surfaces  3  of the crimp die  2  apply compressive forces on tubular portion  5  at angles of 31 degrees from a horizontal axis  6  through a center of the core  26  and vertically at 90 degrees from the horizontal axis  6 , as shown in  FIG. 1 . Three areas of compression are formed with each die  2 . Accordingly, a need exists for a crimp die providing better crimp control of a composite core conductor. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention is to provide an improved electrical connector in which a composite core of a composite core conductor is crimped to the electrical connector. 
         [0007]    Another object of the present invention is to provide an improved electrical connector member in which a composite core conductor is more easily and inexpensively crimped to an electrical connector. 
         [0008]    Another object of the present invention is to provide an improved crimping die that crimps the composite core to an electrical connector without damaging an outer surface of the composite core. 
         [0009]    Another object of the present invention is to provide an improved crimping die proving improved crimp control when crimping a composite core conductor. 
         [0010]    The foregoing objectives are basically attained by an electrical connector including a coupling portion and a tubular portion extending from the coupling portion. A conductor has a non-metallic core surrounded by electrically conductive strands and has a connecting portion of the core extending axially beyond the strands. The connecting portion is received in the tubular portion. A crimped portion on the tubular portion radially engages the connecting portion and secures the conductor to the tubular portion. The crimped portion is formed by concave surfaces on internal surfaces of crimping dies. The concave surfaces have different radii of curvature than remaining portions of the internal surfaces 
         [0011]    The foregoing objectives are also basically attained by a method of crimping a conductor. A portion of electrically conductive strands surrounding a non-metallic core of the conductor is removed from the core. The exposed core of the conductor is inserted in a substantially tubular portion extending from a coupling portion of an electrical connector. The substantially tubular portion is crimped to the core to form a first crimped portion. The first crimped portion is formed by concave surfaces on internal surfaces of crimping dies. The concave surfaces have different radii of curvature than remaining portions of the internal surfaces. 
         [0012]    Objects, advantages, and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses an exemplary embodiment of the present invention. 
         [0013]    As used in this application, the terms “front,” “rear,” “upper,” “lower,” “upwardly,” “downwardly,” and other orientational descriptors are intended to facilitate the description of the exemplary embodiments of the present invention, and are not intended to limit the structure thereof to any particular position or orientation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above benefits and other advantages of the various embodiments of the present invention will be more apparent from the following detailed description of exemplary embodiments of the present invention and from the accompanying drawing figures, in which: 
           [0015]      FIG. 1  is an end elevational view of a conventional die crimping a composite core of a composite core conductor; 
           [0016]      FIG. 2  is an end elevational view of the conventional die of  FIG. 1  showing a gap between the dies prior to crimping; 
           [0017]      FIG. 3  is an end elevational view of a conventional die for crimping a composite core; 
           [0018]      FIG. 4  is an end elevational view of a die crimping a composite core of a composite core conductor in accordance with an exemplary embodiment of the present invention; 
           [0019]      FIG. 5  is an end elevational view of the die of  FIG. 4  prior to crimping; 
           [0020]      FIG. 6  is a perspective view of a die of  FIG. 4 ; 
           [0021]      FIG. 7  is a side elevational view of the die of  FIG. 6 ; 
           [0022]      FIG. 8  is an end elevational view of the die of  FIG. 7 ; 
           [0023]      FIG. 9  is an end elevational view of the die of  FIG. 4  showing a contact area of the die; 
           [0024]      FIG. 10  is an enlarged end elevational view of the contact area of  FIG. 9 ; 
           [0025]      FIG. 11  is an end elevational view of the die of  FIG. 4  with a composite core disposed therein; 
           [0026]      FIG. 12  is a side elevational view in partial cross-section of an assembled electrical connector in accordance with an exemplary embodiment of the present invention; 
           [0027]      FIG. 13  is an exploded side elevational view of the electrical connector of  FIG. 12  prior to assembly; 
           [0028]      FIG. 14  is a side elevational view of a composite core conductor; 
           [0029]      FIG. 15  is an end elevational view of the composite core conductor of  FIG. 14 ; 
           [0030]      FIG. 16  is a side elevational view partially in section of an eyebolt of the electrical connector of  FIG. 12 ; 
           [0031]      FIG. 17  is an end view of the eyebolt of  FIG. 16 ; and 
           [0032]      FIG. 18  is a side elevational view in cross-section of an outer sleeve of the electrical connector of  FIG. 12 ; 
       
    
    
       [0033]    Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0034]    The present invention generally relates to an electrical connector  21  for receiving a composite core conductor  23 , as shown in  FIG. 12 , and a crimp die  25 , as shown in  FIGS. 4-11 , for crimping a composite core  26  of the composite core conductor  23  to the electrical connector  21 . The electrical connector  21  reduces the number of components used in existing electrical connector assemblies, thereby reducing inventory and costs. The crimp dies  25  and  46  of the crimp die set  47  substantially prevent damage to an outer surface  41  of the composite core  26  during the crimping process. 
         [0035]    The composite core conductor  23 , as shown in  FIGS. 14 and 15 , includes a composite core  26  covered by a plurality of aluminum conductors  27 . The composite core  23  is preferably made of a combination of fiber glass and epoxy resin. The plurality of aluminum conductors  27  are wrapped around the composite core  26 . The composite core  26  reduces the weight of the composite core conductor  23  compared to traditional steel core conductors, such that more aluminum conductors can be used, thereby increasing electrical power capacity without increasing the outer diameter of the conductor. Additionally, the more lightweight composite core conductors  23  reduce sag associated with traditional steel core conductors. 
         [0036]    The electrical connector  21  includes an eyebolt  28  having a substantially tubular portion  29  having an open first end  30  and an eyelet  31  connected to a second end  32 , as shown in  FIGS. 12 ,  16  and  17 . An opening  44  in the eyelet  31  allows the electrical connector  21  to be connected to a support, such as a transmission tower. A ridge section  33  is disposed on an outer surface  42  of the tubular portion  29  between the first and second ends  30  and  32 . A cavity  34  having an inner surface  35  extends inwardly from the first end  30  of the eyebolt  28 . Preferably, the eyebolt  28  is unitarily formed as a single piece and is made of metal, such as steel or aluminum. 
         [0037]    The tolerances of the tubular portion  29  are preferably extremely tight to more precisely control the inner and outer diameters thereof. The inner diameter preferably has a tolerance of 0.001 inches. The outer diameter preferably has a tolerance of 0.002 inches. By more precisely controlling the inner and outer diameters of the tubular portion  29 , better control of the crimp between the tubular portion  29  and the core  26  of the composite core conductor  23  is achieved, thereby substantially preventing damage to the composite core during crimping. 
         [0038]    An outer sleeve  36  is substantially tubular and has an outer surface  45  and first and second ends  37  and  38 , as shown in  FIGS. 12 and 18 . A passageway  39  having an inner surface  40  extends from the first end  37  of the outer sleeve  36  to the second end  38 , as shown in  FIG. 18 . Preferably, the diameter of the passageway  39  is substantially constant. Preferably, the outer sleeve  36  is unitarily formed as a single piece and is made of an electrically conductive metal, such as aluminum. 
         [0039]    A crimp die  25  in accordance with an exemplary embodiment of the present invention is shown in  FIGS. 6-11 . First and second dies  25  and  46  form a die set  47  to crimp composite core conductors  23 . Preferably, the first and second dies  25  and  46  are substantially identical. 
         [0040]    The crimp die  25  has a crimping area  7  including first and second crimping surfaces  8  and  9  and a non-crimping surface  10 , as shown in  FIGS. 6-11 . The crimping area  7  extends between first and second substantially planar contact surfaces  48  and  49 , as shown in  FIGS. 6 and 8 . An outer side surface  50  of the die  25  is adapted to be received by a crimping tool (not shown) and extends externally between the first and second substantially planar contact surfaces  48  and  49 . Substantially planar front and rear surfaces  51  and  52  extend between the first and second planar contact surfaces  48  and  49  and are bounded by the outer side surface  50 . Front and rear shoulders  53  and  54  are formed in the front and rear surfaces  51  and  52 , as shown in  FIGS. 6 and 8 . Beveled surfaces  63  and  64  extend along upper edges of the front and rear surfaces  51  and  52  to accommodate flashing or protrusions during the crimping process. 
         [0041]    The non-crimping surface  10  is disposed between the first and second crimping surfaces  8  and  9 . The crimping surfaces  8  and  9  are concave. Center points  55  and  56  of the radii of the first and second crimping surfaces  8  and  9  are spaced from a center point  57  of the radius of the non-crimping surface  10 , as shown in  FIG. 10 , such that the crimping surfaces  8  and  9  have a different radius than the radius of the non-crimping surface  10 . Accordingly, the crimping surfaces  8  and  9  have a different radius of curvature than the non-crimping surface  10 . Preferably, the radii of the first and second crimping surfaces  8  and  9  are longer than the radius of the non-crimping surface  10 . As an example, the radius of the first and second crimping surfaces  8  and  9  is 0.36 inches and the radius of the non-crimping surface  10  is 0.25 inches. 
         [0042]    Preferably, the two concave crimping surfaces  8  and  9  are approximately 90 degrees apart on the crimping surface  7 , as shown in  FIG. 4 . As shown in  FIGS. 9-11 , the concave crimping surfaces  8  increase the contact area  43  between the crimping surface  7  and the tubular portion  29 . The crimps are applied approximately 180 degrees apart on the outer surface of the tubular portion  29  between diametrically opposite concave crimping surfaces  8  and  9  of opposing dies  25 . 
         [0043]    To assemble the electrical connector  21 , a portion of the aluminum conductors  27  are removed from the conductor  23  to expose only the composite core  26 , as shown in  FIGS. 13 and 14 . The exposed composite core  26  is inserted in the cavity  34  of the tubular portion  29  of the eyebolt  28 , as shown in  FIG. 12 . The tubular portion  29  and the composite core  26  are then crimped together in a crimping area  13 , as shown in  FIG. 12 . 
         [0044]    The dies  25  and  46  of  FIGS. 6-11  are used to crimp the tubular portion  29  to the composite core  26  to create a solid crimp connection without damaging the outer surface of the composite core  26 . The crimp tool applies forces vertically on the crimp dies  25  and  46  as indicated by arrows  58  and  59  in  FIG. 11 . The crimping surfaces  8  and  9  are formed having two different radii such that such that the angle of compression is approximately 45 degrees, as shown in  FIG. 4 . Accordingly, applying forces  58  and  59  obliquely to the dies  25  and  46  results in crimping forces being applied at 45 degree angles due to the crimping surfaces  8  and  9  having a different radius than the non-crimping surface  10 . As shown in  FIG. 5 , crimping forces are diametrically opposed such that the crimping forces are applied approximately 180 degrees apart. The concave crimping surfaces  8  and  9  having two different radii portions increases the contact area between the crimping surfaces  8  and  9  and the tubular portion  29  of the eyebolt  28 , as shown in  FIG. 11 . Additionally, the compression dies  25  and  26  apply crimping forces that are diametrically opposed (approximately 180 degrees apart) relative to a longitudinal axis  6  of the composite core such that the composite core  26  is compressed to a substantially circular shape, as shown in  FIGS. 4 and 5 . The compression dies  25  also have very close tolerances. The applied compression forces in the conventional dies, shown in  FIGS. 1 and 2 , result in the core  26  being compressed to an oval shape that could detrimentally affect performance of the conductor. 
         [0045]    Additionally, the tubular portion  29  has very close tolerances on the inner diameter and outer diameter thereof such that a proper amount of travel (or force) is applied during crimping. As shown in  FIG. 4 , close tolerances allow the contact surfaces  48  and  49  to engage during the crimping process, thereby ensuring a proper crimp is obtained. As shown in  FIG. 1 , a gap  4  remains between the opposing dies  2  during the crimping process such that the crimp is not accurately controlled during the crimping process, thereby resulting in under- and over-crimping. The crimp dies  25  and  46  substantially prevent over crimping that can damage the composite core  26  and substantially prevent under crimping that can have a detrimental effect on performance. Accordingly, a better crimp can be obtained that does not substantially damage the outer surface of the composite core  26 . 
         [0046]    As shown in  FIGS. 6 and 8 , the crimping surfaces  8  and  9  of the crimp dies  25  and  46  are concave compared to the planar surfaces  3  of the conventional crimp dies  2  shown in  FIGS. 1-3 . The crimping surface of the conventional dies  2  is comprised of three planar surfaces  3 , as shown in  FIG. 3 . The planar surfaces  3  result in a gap  4  between the crimp dies  2 , as shown in  FIG. 1 . As shown in  FIG. 3 , there is no gap between the crimp dies  25  and  46  during the crimp process when the crimp dies  25  and  46  have fully traveled. Additionally, the planar surfaces  3  provide a smaller area of compression between the surfaces  3  and the composite core  26  and a smaller angle of compression (approximately 31 degrees, as shown in  FIG. 1 ). 
         [0047]    The concave crimping surfaces  8  and  9  in accordance with exemplary embodiments of the present invention as shown in  FIGS. 6-11 , provide a larger area of compression  60 , as shown in  FIG. 11 , and a larger angle of compression (approximately 45 degrees). The dies  25  and  46  also increase the angle of compression to approximately 45 degrees from the 31 degree angle of compression shown in  FIG. 1  for the conventional crimp dies  2 . 
         [0048]    The applied crimping forces  61  are diametrically opposed such that, in combination with the mating contact surfaces  48  and  49  substantially eliminating a gap between the dies  25  and  46  during the crimping process, that the composite core  26  is compressed to a substantially rounded shape. Accordingly, the crimp dies  25  and  46  substantially prevent crimps that damage or otherwise detrimentally affect the composite core  26 . Accordingly, a better crimp can be obtained that does not substantially damage the outer surface of the composite core  26 . 
         [0049]    The crimping surfaces  8  and  9  provide a non-damaging indent on the inner surface  35  of the tubular portion  29  of the eyebolt, as shown in  FIG. 16 . A plurality of the crimps are performed on the outer surface  42  of the tubular portion  29  in a composite core crimping area (first crimping area)  13 , which extends for substantially the length of the cavity  34  in the tubular portion  29 , as shown in  FIG. 12 . When the composite core  26  has been crimped to the tubular portion  29 , the outer sleeve  36  is disposed over the tubular portion  29 , as shown in  FIG. 12 . A first end of the outer sleeve  36  abuts a flange  62  of the eyebolt  28  and a second end of the outer sleeve extends beyond the open end of the tubular portion  29  of the eyebolt  28 . 
         [0050]    The outer sleeve  36  is then crimped in second and third crimping areas  11  and  12 , as shown in  FIG. 12 , thereby securing the conductor  23  to the electrical connector  21 . The outer sleeve  36  is crimped to the eyebolt  28  in the second crimping area  11 . The outer sleeve  36  is crimped to the conductor  23  in the third crimping area  12 . Any suitable crimping dies can be used for the crimping process in the second and third crimping areas  11  and  12 . The outer sleeve  36  is not crimped in the first crimping area  13  in which the tubular portion  29  of the eyebolt  28  is crimped to the composite core  26 . The eye bolt  28  can be anchored to any type of structure. The structure may include, but is not limited to, a pole, a building, a tower, or a substation. 
         [0051]    The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the scope of the present invention. The description of the exemplary embodiments of the present invention is intended to be illustrative, and not to limit the scope of the present invention. Various modifications, alternatives and variations will be apparent to those of ordinary skill in the art, and are intended to fall within the scope of the invention as defined in the appended claims and their equivalents.