Patent Publication Number: US-9899749-B2

Title: Crimp terminal

Description:
TECHNICAL FIELD 
     The present invention relates to a crimp mating terminal to an electric wire. 
     BACKGROUND ART 
     Various types of crimp terminals provided with serrations on a crimping surface have been suggested in the past (e.g., refer to Patent Literature 1). Such a crimp terminal of a conventional example is illustrated in  FIGS. 6 to 8 . In  FIGS. 6 to 8 , an electric wire W connecting a crimp terminal  110  includes a core wire  101  including a plurality of strands  101   a , and an insulation outer skin  102  covering an outer circumference of the core wire  101 . At a tip side of the electric wire W, the insulation outer skin  102  is removed and, thus, the core wire  101  is exposed. 
     The crimp terminal  110  includes a mating terminal connection section  111  and an electric-wire connection section  115 . The electric-wire connection section  115  includes a core-wire crimping section  116  and an outer-skin crimping section  117 . The core-wire crimping section  116  includes a base-bottom section  116   a  and a pair of swaging piece sections  116   b  extended from both sides of the base-bottom section  116   a . On inner surfaces of the base-bottom section  116   a  of the core-wire crimping section  116  and the pair of swaging piece sections  116   b , a number of serrations  118  that are circular recessed sections are formed. The serrations  118  all having a same dimension are arranged almost all over the inner surface of the core-wire crimping section  116 . The outer-skin crimping section  117  includes a base-bottom section  117   a  and a pair of swaging piece sections  117   b  extended from both sides of the base-bottom section  117   a.    
     In the crimp terminal  110 , the exposed core wire  101  is swaged and crimped by the core-wire crimping section  116 , and the insulation outer skin  102  is swaged and crimped by the outer-skin crimping section  117 . 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Laid-Open Publication No. 2009-123623 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, during a swaging and crimping process of the core-wire crimping section  116 , crimping forces applied to the core-wire crimping section  116  are not uniform all over the regions. In other words, as illustrated in  FIGS. 9( a ), 9( b ) and 9( c ) , there are a “region to which a large crimping force is applied” and a “region to which a small crimping force is applied” on the core-wire crimping section  116 . 
       FIG. 9( a )  is a vertical cross-sectional view (cross-sectional view of a face parallel to an axial direction of the core wire  101 ) schematically illustrating a direction in which forces from a swaging jig is applied and illustrating only the core-wire crimping section  116 . As illustrated in  FIG. 9( a ) , depending on a relative positional relationship from both ends of the core-wire crimping section  116  in the axial direction of the core wire  101 , there are regions F 0  and F 2  where the forces from the swaging jig are concentrated during the swaging and crimping process on the core-wire crimping section  116 . Further, in addition to the regions F 0  and F 2 , there is a region F 1  where forces applied between the core wire  101  and the core-wire crimping section  116  become stronger more than necessary. Positions of the regions F 0 , F 1 , and F 2  are determined depending on a shape of the core-wire crimping section  116  and material of the core wire  101  and the like. The regions F 0 , F 1  and F 2  correspond to the “region to which a large crimping force is applied” described above. Further, the regions other than the regions F 0 , F 1 , and F 2  on the core-wire crimping section  116  correspond to the “region to which a small crimping force is applied” described above. 
     As illustrated in  FIGS. 9( b )  and  9 (C), serrations  118  provided in the “region to which a small crimping force is applied” have almost no stretch caused by rolling in local regions and keep a circular shape in a same size. However, serrations  118  provided in the “region to which a large crimping force is applied” are deformed into an oval shape due to large stretch caused by the rolling. As described above, when a size of the serrations  118  is changed, edges of the serrations  118  cannot be effectively used with respect to the stretch of the core wire  101 , thereby suppressing the stretch of the core wire  101 . Thus, there used to be a problem in which, since adhesion among the respective strands  101   a  cannot be efficiently obtained, conduction characteristics between the strands  101   a  are not improved and, thus, electric resistance at crimping positions is increased. 
     The present invention has been made for solving the above-described problems, and an object is to provide a crimp terminal in which the electric resistance at the crimping position of the electric wire can be reduced. 
     Solution to Problem 
     A crimp terminal of the present invention is a crimp terminal including a core-wire crimping section for crimping a core wire of an electric wire including a plurality of strands, wherein first serrations are provided in a first region of the core-wire crimping section on a surface onto which the core wire is to be crimped, and wherein second serrations smaller than the first serrations are provided in a second region of the core-wire crimping section on the surface onto which the core wire is to be crimped, and to which a crimping force larger than that in the first region is applied during a swaging and crimping process. 
     In the crimp terminal according to the present invention, the first serrations or the second serrations may be circular recessed sections. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a crimp terminal before an electric wire is crimped thereto of an embodiment according to the present invention. 
         FIGS. 2( a ), 2( b ) and 2( c )  illustrate an embodiment according to the present invention, in which  FIG. 2( a )  is a side view of the crimp terminal onto which the electric wire is crimped,  FIG. 2( b )  is a vertical cross-sectional view of a core-wire crimping section, and  FIG. 2( c )  is a cross-sectional view taken along a line A-A in  FIG. 2( a ) . 
         FIGS. 3( a ), 3( b ) and 3( c )  illustrate an embodiment according to the present invention, in which  FIG. 3( a )  is a vertical cross-sectional view of the core-wire crimping section that schematically illustrates a direction in which a force from a swaging jig is applied,  FIG. 3( b )  is an exploded view of the core-wire crimping section before crimping, and  FIG. 3( c )  is an exploded view of the core-wire crimping section after the crimping. 
         FIG. 4  is a perspective view of a swaging jig of an embodiment according to the present invention 
         FIG. 5  is a side view illustrating a swaging work with the swaging jig of the embodiment according to the present invention. 
         FIG. 6  is a perspective view of the crimp terminal before the electric wire is crimped thereto according to a conventional example. 
         FIG. 7  is a side view of the crimp terminal to which the electric wire is crimped according to the conventional example. 
         FIG. 8  is a cross-sectional view taken along a line of B-B in  FIG. 7  according to the conventional example. 
         FIGS. 9( a ), 9( b ) and 9( c )  illustrate the conventional example, in which  FIG. 9( a )  is a vertical cross-sectional view of only the core-wire crimping section that schematically illustrates a direction in which a force from a swaging jig is applied,  FIG. 9( b )  is an exploded view of the core-wire crimping section before crimping, and  FIG. 9( c )  is an exploded view of the core-wire crimping section after the crimping. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     With reference to figures, an embodiment according to the present invention will be described below. 
       FIGS. 1 to 5  illustrate the embodiment according to the present invention. As illustrated in  FIGS. 1 and 2 , the electric wire W includes a core wire  1  including a plurality of strands  1   a  and an insulation outer skin  2  covering an outer circumference of the core wire  1 . At a tip side of the electric wire W, the insulation outer skin  2  is removed and, thus, the core wire  1  is exposed. The core wire  1  includes a number of strands  1   a  made of aluminum or aluminum alloy (hereinafter referred to as “made of aluminum,” and a number of the strands  1   a  are twisted with each other. In other words, the electric wire W is an aluminum electric wire. 
     The crimp terminal  10  is, for example, made of copper alloy and formed by bending a plate cut into a predetermined shape. The crimp terminal  10  includes a mating terminal connection section  11  and an electric-wire connection section  15 . The electric-wire connection section  15  includes a core-wire crimping section  16  and an outer-skin crimping section  17 . 
     The core-wire crimping section  16  includes a base-bottom section  16   a  and a pair of swaging piece sections  16   b  extended from both sides of the base-bottom section  16   a . On inner surfaces of the base-bottom section  16   a  of the core-wire crimping section  16  and the pair of swaging piece sections  16   b  (surfaces onto which the core wire  1  is crimped), a number of the serrations  18   a ,  18   b  that are a number of circular recessed sections are provided in a dotted manner almost all over the region. Configurations of the serrations  18   a ,  18   b  will be described in detail below. 
     The outer-skin crimping section  17  includes a base-bottom section  17   a  and a pair of swaging piece sections  17   b  extended from both sides of the base-bottom section  17   a.    
     In the crimp terminal  10 , the exposed core wire  1  is swaged and crimped by the core-wire crimping section  16 , and the insulation outer skin  2  is also swaged and crimped by the outer-skin crimping section  17 . 
     Subsequently, the serrations  18   a ,  18   b  will be described. As illustrated in  FIG. 3( b ) , the serrations  18   a ,  18   b  are provided at almost equal intervals along an axial direction of the core wire  1  almost all over the region on the inner surface of the core-wire crimping section  16 . The serrations  18   a ,  18   b  are circular recessed sections. The serrations  18   a ,  18   b  are provided such that the large serrations  18   a  (first serrations) are arranged in a region to which a small crimping force is applied during the swaging process, and a small serrations  18   b  (second serrations) are arranged in a region to which a large crimping force is applied during the swaging process. 
     The large serrations  18   a  (first serrations) are larger in a size than the small serrations  18   b  (second serrations). A size of the serrations refers to a diameter of the serrations or a depth thereof. 
     As illustrated in  FIG. 3( a ) , the regions to which the large crimping force is applied during the swaging process are regions E 0 , E 2  about a position where an auxiliary extending line at an angle of 45 degrees from both end positions of a swaging jig  20  intersects with the base-bottom section  16   a . The small serrations  18   b  are provided in the regions E 0 , E 2 . Further, in addition to the regions E 0 , E 2 , there is a region E 1  where forces applied between the core wire  1  and the core-wire crimping section  16  become stronger more than necessary. When the core wire  1  is made of aluminum as in the present embodiment, compared to the core wire  1  made of the copper alloy, the core wire  1  is further overly crimped in the region E 1 . In the region E 1  also, the small serrations  18   b  are provided. The positions of the regions E 0 , E 1 , E 2  are determined depending on a shape of the core-wire crimping section  16  and material of the core wire  1 . 
     Of the surfaces of the core-wire crimping section  16  onto which the core wire  1  is crimped, in the regions other than the regions E 0 , E 1 , E 2 , the small crimping forces are applied during the swaging process and, thus, the large serrations  18   a  are provided. 
     Of the surfaces of the core-wire crimping section  16  onto which the core wire  1  is crimped, the regions other than the regions E 0 , E 1 , E 2  are the “region to which a small crimping force is applied” (first regions). Of the surfaces of the core-wire crimping section  16  onto which the core wire  1  is crimped, the regions indicated with the regions E 0 , E 1 , E 2  correspond to the “region to which a large crimping force is applied” (second regions). The crimping force applied to the first region is smaller than that applied to the second region. 
     In other words, of the surfaces of the core-wire crimping section  16  onto which the core wire  1  is crimped, in the regions other than the regions E 0 , E 1 , E 2  (first regions), the serrations  18   a  (first serrations) are provided. On the other hand, in the regions E 0 , E 1 , E 2  (second regions) to which the larger crimping force is applied compared to the regions other than the regions E 0 , E 1 , E 2  during the swaging and crimping process, the serrations  18   b  (second serrations) are provided. 
     The crimp terminal  10  is crimped by the swaging jig  20  illustrated in  FIG. 4 . The swaging jig  20  includes a swaging groove  21  having an outer circumferential shape of final swaging at a swaging tip side. As illustrated in  FIG. 5 , when the pair of core-wire swaging piece sections  16   b  are pressed from above by the swaging jig  20 , the pair of swaging piece sections  16   b  are plastic-deformed along the swaging groove  21 . 
     During the swaging and crimping process, the core wire  1  receives the crimping forces from the core-wire crimping section  16  and, accordingly, each of the strands  1   a  of the core wire  1  gets into the serrations  18   a ,  18   b  so that the strands  1   a  is stretched to generate a newly born surface. 
     Further, during the swaging and crimping process, the large crimping force is applied to the regions E 0 , E 1 , E 2  (second regions) including the small serrations  18   b  (second serrations). However, since the regions E 0 , E 1 , E 2  (second regions) include a large thick region (region other than serrations  18   b ), almost no stretch is generated by the rolling, and thus deformation of the serrations  18   b  can be suppressed. 
     On the other hand, in the regions of the large serrations  18   a  (first serrations), in other words, in the regions (first regions) other than the regions E 0 , E 1 , E 2 , since only small crimping force is applied, even if there is the large thin region (the region of the serrations  18   a ), almost no stretch is generated by the rolling, and thus the serrations  18   a  are not deformed. 
     As described above, since the deformation of the serrations  18   a ,  18   b  can be suppressed, edges of the serrations  18   a ,  18   b  can be effectively used with respect to the stretch of the core wire  1  to promote the stretch thereof. With this arrangement, the adhesion among the strands  1   a  can be efficiently obtained to improve the conduction characteristics between the strands  1   a , thereby reducing the electric resistance at the crimping point. 
     Further, since the each of the strands  1   a  gets into the serrations  18   a ,  18   b , tensile strength between the core wire  1  and the core-wire crimping section  16  can be improved (mechanical strength is improved). 
     As described above, design of a part of the crimp terminal  10  is changed (size change of the serrations) to improve the conduction characteristics of the core wire  1  at the crimping point. Therefore, the electric resistance at the crimping point can be reduced without raising costs compared to making the core wire into a single line. 
     The core wire  1  is made of aluminum. An oxidized film produced on a surface of the strands  1   a  and made of the aluminum is harder compared to that of the copper alloy. Therefore, the core wire  1  made of the aluminum used to have a problem of an increase of the electric resistance due to the conduction resistance between the strands  1   a . However, according to the present invention, since the conduction resistance between the strands  1   a  can be reduced, the present invention is effective particularly for the aluminum electric wire. The core wire  1  made of aluminum is softer and stretched more easily compared to that made of copper alloy. However, as described above, since stress transferring loss from the core-wire crimping section  16  to the core wire  1  can be reduced, the present invention is effective particularly for the aluminum electric wire also from this point of view. 
     According to the embodiment, the serrations  18   a ,  18   b  are the circular recessed sections, however, of course, they may be recessed sections having other shapes (oval, triangle, square (including diamond), polygonal shape including more than four sides, and a star-like shape). 
     According to the embodiment, the core wire  1  is made of aluminum, however, the present invention can be applied to the core wire  1  made of material other than aluminum (e.g., made of copper alloy). When the core wire is made of copper alloy, the serrations provided in the region E 1  illustrated in  FIG. 3( b ) ,  FIG. 3( c )  are made in a large size. 
     The embodiment according to the present invention described as above is only an example described for easier understanding of the present invention, and the present invention is not limited to the embodiment described above. The technical aspect of the present invention is not limited to specific technical items disclosed in the above described embodiment, but include various changes, modifications, and alternative techniques that can be easily directed from the above described embodiment. 
     The present application claims the priority based on Japanese Patent Application No. 2013-216974 filed on the Oct. 18, 2013, and the whole contents of the application are incorporated into the present specification as reference. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, during the swaging and crimping process, the large crimping force is applied to the region of the small serrations. However, since the thin region (other region of small serrations) is large, almost no stretch is generated by the rolling, and thus deformation of the serrations can be suppressed. On the other hand, in the region of the large serrations, since only small crimping force is applied, even if the thin region (region of the large serrations) is large, almost no stretch is generated by the rolling, and the serrations are not deformed. As described above, since the deformation of the serrations can be suppressed, the edges of the serrations can be effectively used with respect to the stretch of the core wire, thereby promoting the stretch of the core wire. With this arrangement, the adhesion among the strands can be efficiently obtained to improve the conduction characteristics between the strands, thereby reducing the electric resistance at the crimping point. 
     REFERENCE SIGNS LIST 
     
         
         W electric wire 
           1  core wire 
           1   a  strand 
           10  crimp terminal 
           16  core-wire crimping section 
           18   a  large serration (first serration) 
           18   b  small serration (second serration)