Abstract:
A method is provided for preparing a wire for installation of a terminal. The method comprises removing an insulating layer from a conductor to expose a portion of a conductor. The method further includes attaching a conductive foil layer to a portion of the exposed portion of the conductor by applying pressure to the conductive foil layer. Terminated wires are also provided.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 14/873,237, filed Oct. 2, 2015, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/059,317, filed Oct. 3, 2014, the contents of each of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The articles and methods described below generally relate to the field of preparing a wire to receive a contact element. 
       BACKGROUND 
       [0003]    Automotive cables, such as a battery cable, can include an aluminum conductor which can be lighter and less expensive than conventional copper conductors. A contact element, such as a ring terminal, is crimped or otherwise secured to a bare end of the aluminum conductor to form a terminated end. The contact element is typically made from copper based alloys such as brass, for example, or another material that is different than aluminum. 
         [0004]    The bare end of aluminum conductor, however, can be susceptible to oxidation (e.g., sapphire oxidation) which can inhibit conductivity between the bare end and the contact element and thus can prevent proper termination with a contact element. The aluminum conductor can also be susceptible to galvanic corrosion when it is terminated to a material that is more basic than aluminum, such as brass, and when moisture is present at the interface between the conductor and the contact element. The galvanic corrosion can cause aluminum dissolution which can adversely affect the conductivity between the aluminum conductor and the contact element. Once terminated, the aluminum conductor can be more susceptible to mechanical creep at its terminated end at low temperatures (e.g., 80 degrees C.) than conventional copper conductors which can result in undesirable impedances. The aluminum conductor is also weaker than a copper conductor which can result in the aluminum conductor being easier to pull out of the contact element after termination. 
       SUMMARY 
       [0005]    In accordance with one embodiment, a method for preparing a wire to accept a contact element is provided. The wire comprises a conductor and an insulating layer surrounding the conductor. The conductor is formed of a first material. The method comprises removing the insulating layer from the conductor to expose a portion of the conductor. The method further comprises joining a conductive foil layer and at least a portion of the exposed portion of the conductor together. The conductive foil layer is formed of a second material. 
         [0006]    In accordance with another embodiment, a method for installing a contact element on a wire is provided. The wire comprises a conductor. The conductor comprises an exposed portion and is formed of a first material. The method comprises joining a conductive foil layer and the exposed portion of the conductor together. The method further comprises securing the contact element to the exposed portion of the conductor and the conductive foil layer. The conductive foil layer is formed of a second material. The terminal is formed of a third material. 
         [0007]    In accordance with yet another embodiment, a terminated wire comprises a conductor. The conductor comprises an exposed portion and is formed of a first material. The terminated wire is prepared by the process of joining a conductive foil layer and an exposed portion of the conductor together and securing a contact element to the exposed portion of the conductor and the conductive foil layer. The conductive foil layer is formed of a second material. The contact element is formed of a third material. 
         [0008]    In accordance with yet another embodiment, a terminated wire comprises a wire, a conductive foil layer, and a contact element. The wire comprises a conductor. The conductor comprises an exposed portion and is formed of a first material. The conductive foil layer is formed of a second material. The contact element is formed of a third material. The conductive foil layer is joined to the exposed portion of the conductor. The terminal is secured to the exposed portion of the conductor and the conductive foil layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    It is believed that certain embodiments will be better understood from the following description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a perspective view depicting a wire, a conductive foil layer, and a terminal prior to the conductive foil layer being installed on a conductor of the wire, in accordance with one embodiment; 
           [0011]      FIG. 2  is a perspective view depicting the conductive foil layer installed on the wire of  FIG. 1 ; 
           [0012]      FIG. 3  is a perspective view of the terminal installed on the wire of  FIG. 1 ; 
           [0013]      FIG. 4  is a cross-sectional view taken along the line  4 - 4  in  FIG. 3 ; 
           [0014]      FIG. 5  is a perspective view depicting a wire, a conductive foil layer, and a terminal prior to the conductive foil layer being installed on a conductor of the wire, in accordance with another embodiment; 
           [0015]      FIG. 6  is a perspective view of the terminal installed on the wire of  FIG. 5 ; 
           [0016]      FIG. 7  is a cross-sectional view taken along the line  7 - 7  in  FIG. 6 ; 
           [0017]      FIG. 8  a perspective view depicting a wire, a conductive foil layer, and a terminal prior to the conductive foil layer being installed on a conductor of the wire, in accordance with another embodiment; 
           [0018]      FIG. 9  is a perspective view depicting a wire and ferrule prior to the ferrule being installed on a conductor of the wire, in accordance with another embodiment; and 
           [0019]      FIG. 10  is a perspective view of the wire of  FIG. 9 , but with the ferrule installed on the conductor. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    In connection with the views and examples of  FIGS. 1-10 , wherein like numbers indicate the same or corresponding elements throughout the views,  FIG. 1  illustrates a wire  10  having a conductor  12  and an insulating layer  14  surrounding the conductor  12 . A portion of the insulating layer  14  is shown to be removed from the conductor  12  to expose a bare of the conductor  12 . The insulating layer  14  can be removed with any of a variety of suitable methods, such as through interaction with a set of wire strippers. Although a multi-strand insulated conductor is shown, it will be appreciated that any of a variety of suitable alternative conductors can be used having different quantities/sizes of strands, including a conductor having an individual strand (e.g., a solid conductor) and/or being devoid of insulation (e.g., a grounding conductor. 
         [0021]    As illustrated in  FIGS. 1 and 2 , a conductive foil layer  18  can be attached to a portion of the bare portion  16  of the conductor  12 . In one embodiment, the conductive foil layer  18  can be wrapped around the bare portion  16  of the conductor  12 , as illustrated in  FIG. 2 , and pressure can be applied to the conductive foil layer  18  (in the direction of the arrows P). In one embodiment, the application of pressure to the conductive foil layer  18  can be the result of simply overlying the conductive foil layer  18  onto the bare portion  16  of the conductor  12  (e.g., by grasping the ends of the conductive foil layer  18  and wrapping it around the bare portion  16 ). In certain embodiments, the desired pressure can be applied by hand, with a tool (e.g., pliers), or any of a variety of other suitable methods. 
         [0022]    Once the conductive foil layer  18  has been provided onto the bare portion  16  of the conductor  12 , the bare portion  16  of the conductor  12  and the conductive foil layer  18  can be joined together. In one embodiment, the bare portion  16  and the conductive foil layer  18  can be joined together through welding, such as through ultrasonic welding, for example. Welding the bare portion  16  and the conductive foil layer  18  together can bond the conductive foil layer  18  to the conductor  12  as well as bond the strands of the conductor  12  together to form an amalgamated mass (e.g., a nugget). Welding can also help break apart any oxidation formed on the conductor  12  that might adversely affect the conductivity between the conductor  12  and the conductive foil layer  18 . Welding can accordingly enhance the conductivity characteristics between the conductor  12  and the conductive foil layer  18 . 
         [0023]    Once the conductor  12  and the conductive foil layer  18  have been joined together, a terminal  20  can be slid over the conductive foil layer  18  and secured to the amalgamated mass of the bare portion  16  and the conductor  12 , such as with a crimping tool, for example, to create a terminated wire  21 , as illustrated in  FIGS. 3 and 4 . In one embodiment, as illustrated in  FIG. 3 , an exterior surface  22  of a crimping portion  24  of the terminal  20  can be reinforced, such as by applying solder  26  at a separation point  28  of the crimping portion  24 , to enhance the durability of the connection between the terminal  20  and the conductor  12 . In certain embodiments, the terminal  20  can be nickel plated, or plated with another conductive material, prior to attachment of the terminal  20  to the conductor  12 . In such an embodiment, the nickel plating can protect the terminal from galvanic corrosion to enhance the conductivity between the conductor  12  and the material that forms the terminal  20  (e.g., brass). The terminated end can additionally or alternatively be dipped in molten solder to enhance durability of the terminated wire  21 . It is to be appreciated that although the terminal  20  is shown to be a ring terminal, it is to be appreciated that any of a variety of suitable alternative contact elements, such as a slotted terminal, a bus bar, or a termination block, for example, can be attached to the wire  10 . It is also to be appreciated that the terminated wire  21  is contemplated for use in a variety of suitable applications, such as, for example, as a vehicular battery cable. 
         [0024]    The conductor  12  and the conductive foil layer  18  can be formed of different conductive materials with the conductive foil layer  18  having about the same or higher conductivity than the conductor  12 . As a result, when the conductive foil layer  18  is interposed between the conductor  12  and the terminal  20 , the conductive foil layer  18  can enhance the overall conductivity between the conductor  12  and the terminal  20  as compared to the conductive foil layer  18  not being present (i.e., the conductor  12  and the terminal  20  being entirely in contact with each other). In one embodiment, the conductor  12  can be formed of aluminum or an aluminum alloy, the conductive foil layer  18  can be formed of copper, and the terminal  20  can be formed of brass. In such an embodiment, the copper of the conductive foil layer  18  can allow the interaction between the aluminum conductor  12  and the brass terminal  20  to be more conductive than crimping the brass terminal  20  directly to the aluminum conductor  12  (which in some instances can be non-conductive). It is to be appreciated that the conductive foil layer  18  can be formed of a material that is as conductive as or more conductive than the conductor  12 . In certain embodiments, the conductor  12  can be formed of a conductive material having a conductivity of about 3.5*10 7  S/m (at 20 degrees C.) or less, and the conductive foil layer  18  can be formed of conductive material having a conductivity of about 4.1*10 7  S/m (at 20 degrees C.) or more. In other embodiments, the conductor  12  can be formed of a conductive material that is substantially susceptible to oxidation, such as an aluminum alloy, a chromium alloy, and/or a magnesium alloy, and the conductive foil layer  18  can be formed of conductive material that is not substantially susceptible to oxidization such as a copper alloy, silver, nickel, and/or gold. It is to be appreciated that the different metals described above for the conductor  12 , the conductive foil layer  18 , and the terminal  20  can be any of a variety of different metals or metal alloys, such as, for example copper or copper alloys, such as brass. 
         [0025]    As illustrated in  FIG. 1 , the conductive foil layer  18  is shown to have a length L 1 , a width W, and a thickness T and the bare portion  16  of the conductor  12  is shown to have a length L 2 , a diameter D, and a circumference C. In one embodiment, the length L 1  and width W of the conductive foil layer  18  can be less than the circumference C and the length L 2  of the bare portion  16  of the conductor  12 , respectively, such that when the conductive foil layer  18  is attached to the conductor  12 , the conductive foil layer  18  neither reaches the end of the conductor  12  nor completely surrounds it. In another embodiment, the length L 1  of the conductive foil layer  18  can be more than the circumference C of the bare portion  16  of the conductor  12 , respectively, such that when the conductive foil layer  18  is attached to the conductor  12 , the conductive foil layer  18  overlaps at its ends such that it entirely surrounds the bare portion  16 . In certain embodiments, the diameter D of the conductor can be significantly more than the thickness T of the conductive foil layer  18 , and can in certain embodiments have a ratio of between about 100:1 and about 500:1 and in certain embodiments can have a ratio of about 200:1. In one embodiment, for a 0 AWG wire, the length L 1  can be about 40 mm, the width W can be about 18 mm, the thickness T can be about 0.035 mm, the length L 2  can be about 20 mm, the diameter D can be about 8 mm, and the circumference C can be about 25 mm. It will be appreciated that a layer described herein as being a foil, such as conductive foil layer  18 , should be understood to mean that the layer is a sheet-like substrate having a length and width that are substantially greater than the thickness of the substrate. In certain embodiments, ratio of the combined length and width of the layer to the thickness of the layer can be between about 500:1 to about 100,000:1. In certain embodiments, the ratio can be about 10,000:1 to about 25,000:1 and preferably about 14,000:1 
         [0026]    In some embodiments, the bare portion  16  of the conductor  12 , alone or in combination with the conductive foil layer  18 , can be cleaned before or after application of the conductive foil layer  18  to remove any oxides on the conductor  12  and/or between the conductor  12  and the conductive foil layer thus enhancing the effectiveness of the conductivity between the conductor  12 , the conductive foil layer  18 , and the terminal  20 . In one embodiment, the conductor  12  and/or conductive foil layer  18  can be cleaned via a plasma treatment performed by a blown-ion air system (not shown). The blown-ion air system can force pressurized air towards an electrode, through a narrow nozzle, and onto the bare portion  16 . The electrode creates positively charged ions in the pressurized air which is then accelerated by the nozzle and provided onto the bare portion  16  of the conductor  12 . The positively charged ions in the airstream positively charge the outer surface of the bare portion  16  thereby increasing its surface energy to remove any oxides. In another embodiment, the conductor  12  and/or conductive foil layer  18  can be cleaned via a high temperature induction heating process that applies a flame to the conductor  12  and/or conductive foil layer  18  using any of a variety of fuels, such as, for example, hydrogen gas, alcohol, and/or acetylene. 
         [0027]    In certain embodiments, the bare portion  16  of the conductor  12  and the conductive foil layer  18  can be joined by soldering such as by dipping the bare portion  16  and the conductive foil layer  18  together in a molten material (e.g., such as molten tin) or resistance soldering the bare portion  16  and the conductive foil layer  18  together, for example, both of which can enhance the conductivity between the bare portion  16 , the conductive foil layer  18 , and the terminal  20 . It is to be appreciated that cleaning the bare portion  16  and/or the conductive foil layer  18  can encourage the application of solder. However, the soldering can be performed in addition to the welding or in addition to or in lieu of the cleaning described above. It is also to be appreciated that the bare portion  16  and/or the conductive foil layer  18  can undergo any of a variety of other suitable treatment processes to prepare for affixation of the terminal  20 . 
         [0028]      FIGS. 5-7  illustrate a wire  110 , a conductive foil layer  118  and a terminal  120  that are similar to, or the same in many respects as, the wire  10 , the conductive foil layer  18  and the terminal  120 , respectively, illustrated in  FIGS. 1-4 . For example, the wire  110  can include a conductor  112 , an insulating layer  114 , a bare portion  116 , and a conductive foil layer  118 . However, the conductive foil layer  118  can be joined to the bare portion  116  of the conductor  112  by applying pressure to the conductive foil layer  118  (in the direction of the arrows P) and without any welding (ultrasonic or otherwise). In such an arrangement, the terminal  20  can be slid over the bundle of strands (e.g.,  123 ) at the bare portion  16  and secured to the bundle of strands (e.g.,  123 ), such as with a crimping tool, for example. An exterior surface  122  of a crimping portion  124  of the terminal  120  can be reinforced, such as by applying solder  126  at a separation point  128  of the crimping portion  124 . 
         [0029]      FIG. 8  illustrates a wire  210 , a conductive foil layer  218  and a terminal  220  that are similar to, or the same, in many respects as the wire  10 , the conductive foil layer  18  and the terminal  20 , respectively, illustrated in  FIGS. 1-4 . For example, the wire  210  can include a conductor  212 , an insulating layer  214 , and a bare portion  216 . The conductive foil layer  218 , however, can be a corrugated screen having a plurality of elevated portions (e.g., points) distributed along upper and lower surfaces (upper surface  230  shown). When the conductive foil layer  218  is attached to the bare portion  216  of the conductor  212 , the points can abrade the bare portion  216  of the conductor  212  (e.g., remove any oxidation) to facilitate effective electrical contact between the bare portion and the conductive foil layer  218 . If the bare portion  216  and the conductive foil layer  218  are joined by soldering, as described above, the solder can collect in pockets defined between the points to facilitate effective bonding between the bare portion  216  and the conductive foil layer  218 . In one embodiment, the conductive foil layer  218  can be formed of nickel and the conductor  212  can be formed of aluminum  212 . 
         [0030]      FIGS. 9-10  illustrate a wire  310  that is similar to, or the same, in many respects as the wire  10  illustrated in  FIGS. 1-4 . For example, the wire  310  can include a conductor  312 , an insulating layer  314 , and a bare portion  316 . A ferrule  331 , however, can be provided in lieu of, or in addition to, a conductive foil layer (e.g.,  18 ). The ferrule  331  can be joined to the bare portion similarly as described above and a terminal (not shown) can then be secured thereto. 
         [0031]    Another alternative embodiment of a terminated wire (e.g., an alternative terminated wire) is also contemplated. The alternative terminated wire can be similar in many respects to the terminated wire  21  described above except that the alternative terminated wire does not include a conductive foil layer (e.g.,  18 ). To prepare the alternative terminated wire, a portion of an insulating layer (e.g.,  14 ) can be removed from a conductor (e.g.,  12 ) to expose a bare portion (e.g.,  16 ) of the conductor (e.g.,  12 ). The bare portion can then be cleaned (e.g., with a plasma treatment) and welded (e.g., through ultrasonic welding) to bind individual strands of the conductor together. The steps of cleaning and welding can be performed in any order. Once welded, the bare portion can be soldered (e.g., through tin dipping or resistive soldering). A terminal (e.g.,  20 ) can then be attached to the bare portion insulating layer to create the alternative terminated wire. In one embodiment, the conductor  112  can be formed of aluminum and the conductive foil layer can be formed of nickel. 
       Examples 
       [0032]    Testing was conducted on a terminated wire similar to the terminated wire  21  described above. The terminated wire that was tested was a 0 AWG (I/O) aluminum wire having a bare portion (e.g.,  14 ) measuring about 20 mm, a copper conductive foil layer (e.g.,  18 ) having a length (e.g., L 1 ) of about 40 mm, a width (e.g., W) of about 18 mm, and a thickness (e.g., T) of about 0.035 mm, and a brass terminal. The copper conductive foil layer was manually wrapped onto the bare portion and then was ultrasonically welded to form a nugget. A terminal was then crimped onto the nugget. Ten separate resistance tests were then performed to measure the resistance between the conductor and the terminal (e.g., between points A and B illustrated on  FIG. 3 ). Each test resulted in a resistance between 0.041 Ohms and 0.045 Ohms, having an example resistance of 0.043 Ohms. The maximum allowable resistance for use as a vehicular battery cable is 0.057 Ohms. 
         [0033]    Comparative testing was also conducted to compare the results for different terminations of a 0 AWG (I/O) aluminum wire having a bare portion (e.g.,  14 ) measuring about 20 mm, a copper conductive foil layer (e.g.,  18 ) having a length (e.g., L 1 ) of about 40 mm, a width (e.g., W) of about 20 mm, and a thickness (e.g., T) of about 0.035 mm, and a brass terminal. A variety of different terminated wires were assembled using certain of the methodologies described above and resistance tests were performed on the terminated wires. The results of the resistance tests are as follows: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Example 
                 Termination Method 
                 Resistance (Ohms) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Example #1 
                 Bare Conductor with Terminal 
                 Open Circuit 
               
               
                   
                 Crimped Directly to Bare Conductor 
                 (high resistance) 
               
             
          
           
               
                 Example #2 
                 Terminated Conductor Prepared 
                 0.345 
                 milliohms 
               
               
                   
                 and Terminated Without 
               
               
                   
                 Conductive Foil Layer as 
               
               
                   
                 Follows: 
               
             
          
           
               
                   
                 1. 
                 Ultrasonically Weld Bare 
                   
                   
               
               
                   
                   
                 Conductor 
               
               
                   
                 2. 
                 Plasma Clean Welded 
               
               
                   
                   
                 Bare Conductor 
               
               
                   
                 3. 
                 Dip Bare Conductor in 
               
               
                   
                   
                 Molten Solder 
               
               
                   
                 4. 
                 Crimp Terminal to 
               
               
                   
                   
                 Soldered End of Bare 
               
               
                   
                   
                 Conductor. 
               
               
                   
                 5. 
                 Resistance Solder Outer 
               
               
                   
                   
                 Surface of Terminal 
               
             
          
           
               
                 Example #3 
                 Terminated Conductor Prepared 
                 0.179 
                 milliohms 
               
               
                   
                 and Terminated Without 
               
               
                   
                 Conductive Foil Layer as 
               
               
                   
                 Follows: 
               
             
          
           
               
                   
                 1. 
                 Plasma Clean Bare 
                   
                   
               
               
                   
                   
                 Conductor 
               
               
                   
                 2. 
                 Ultrasonically Weld Bare 
               
               
                   
                   
                 Conductor 
               
               
                   
                 3. 
                 Plasma Clean Bare 
               
               
                   
                   
                 Conductor 
               
               
                   
                 4. 
                 Dip Bare Conductor in 
               
               
                   
                   
                 Molten Solder 
               
               
                   
                 5. 
                 Crimp Terminal to 
               
               
                   
                   
                 Soldered End of Bare 
               
               
                   
                   
                 Conductor. 
               
               
                   
                 6. 
                 Resistance Solder Outer 
               
               
                   
                   
                 Surface of Terminal 
               
             
          
           
               
                 Example #4 
                 Terminated Conductor Prepared 
                 0.046 
                 milliohms 
               
               
                   
                 and Terminated With Solid 
               
               
                   
                 Copper Conductive Foil Layer 
               
               
                   
                 as Follows: 
               
             
          
           
               
                   
                 1. 
                 Ultrasonically Weld Bare 
                   
                   
               
               
                   
                   
                 Conductor and 
               
               
                   
                   
                 Conductive Foil Layer 
               
               
                   
                   
                 Together 
               
               
                   
                 2. 
                 Dip Welded End in 
               
               
                   
                   
                 Molten Solder 
               
               
                   
                 3. 
                 Crimp Terminal to 
               
               
                   
                   
                 Soldered End of Bare 
               
               
                   
                   
                 Conductor. 
               
               
                   
                 4. 
                 Resistance Solder Outer 
               
               
                   
                   
                 Surface of Terminal 
               
               
                   
                   
               
             
          
         
       
     
         [0034]    The foregoing description of embodiments and examples of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the forms described. Numerous modifications are possible in light of the above teachings. Some of those modifications have been discussed and others will be understood by those skilled in the art. The embodiments were chosen and described in order to best illustrate the principles of the disclosure and various embodiments as are suited to the particular use contemplated. The scope of the disclosure is, of course, not limited to the examples or embodiments set forth herein, but can be employed in any number of applications and equivalent devices by those of ordinary skill in the art. Rather it is hereby intended the scope of the invention be defined by the claims appended hereto. Also, for any methods claimed and/or described, regardless of whether the method is described in conjunction with a flow diagram, it should be understood that unless otherwise specified or required by context, any explicit or implicit ordering of steps performed in the execution of a method does not imply that those steps must be performed in the order presented and may be performed in a different order or in parallel.