Abstract:
Multi-stranded wires are clamped between an ultrasonic welding tip and an opposing anvil. The multi-stranded wires are made of a material that is more malleable than copper, or of a material that has a malleability that is substantially the same or greater than the malleability of aluminum. The plurality of multi-stranded wires can be clamped between opposing side surfaces to further form the wire bundle. Ultrasonic energy is applied to a first side of the wire bundle adjacent the ultrasonic welding tip. After termination of ultrasonic energy to the first side, the wire bundle is rotated 180 degrees relative to the anvil and ultrasonic energy is applied to a second side of the wire bundle, wherein the second side is oppositely disposed relative to the first side.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/836,882 filed on Jun. 19, 2013. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to methods of ultrasonically welding multi-stranded malleable wires together. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    Multi-stranded wires are sometimes ultrasonically welded together. Difficulties can arise, however, when such multi-stranded wires have a malleability that is similar to aluminum or other materials that have a malleability that is greater than copper. These difficulties can be particularly problematic when the volume or number of wire strands is relatively large. For example, using typical ultrasonic wire welding devices and methods with wires made using such malleable materials can fail to adequately transfer sufficient ultrasonic energy throughout the entire volume of wire strands. As the ultrasonic tip begins to weld and soften the wires closest to it, then sufficient energy is not induced to the other side of the bundle of wires to create a strong consistent weld throughout the entire bundle of wires. This can result in a weak or partial weld where some of the wire strands fail to be sufficiently welded together. 
       SUMMARY 
       [0005]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features, nor should every feature described herein be considered an essential feature of the disclosure. 
         [0006]    A method of ultrasonically welding a plurality of multi-stranded wires together includes positioning a plurality of multi-stranded wires between an ultrasonic welding tip and an opposing anvil. The multi-stranded wires are made of a material that is more malleable than copper, or of a material that has a malleability that is substantially the same or greater than the malleability of aluminum. The plurality of multi-stranded wires are clamped between the ultrasonic welding tip and the opposing anvil to form a wire bundle. The plurality of multi-stranded wires can also be clamped between opposing side surfaces to further form the wire bundle. Ultrasonic energy is applied to a first side of the wire bundle adjacent the ultrasonic welding tip. The application of ultrasonic energy to the first side is terminated. The bundle can be allowed to harden and/or the wire bundle is rotated 180 degrees. After termination of ultrasonic energy to the first side, ultrasonic energy is applied to a second side of the wire bundle, wherein the second side is oppositely disposed relative to the first side. 
         [0007]    A method of ultrasonically welding a plurality of multi-stranded wires together includes positioning a plurality of multi-stranded wires between an ultrasonic welding tip and an opposing anvil. A user can initiate a control sequence wherein a controller is programmed to automatically cause the ultrasonic welder to automatically carry out a predetermined welding process without further intervention of the operator. The predetermined welding process can include clamping the plurality of multi-stranded wires between the ultrasonic welding tip and the opposing anvil to form a wire bundle. The plurality of multi-stranded wires can also be clamped between opposing side surfaces to further form the wire bundle. Ultrasonic energy is applied to a first side of the wire bundle adjacent the ultrasonic welding tip. The application of ultrasonic energy to the first side is terminated and the sides are automatically unclamped from the wire bundle. The ultrasonic welder can automatically pause, allowing the user to manually rotate the wire bundle 180 degrees, or the ultrasonic welder can automatically rotate the wire bundle 180 degrees, and/or the partially-welded bundle can be allowed to harden. The plurality of multi-stranded wires can again be clamped between the ultrasonic welding tip and the opposing anvil to form a wire bundle. The plurality of multi-stranded wires can also again be clamped between opposing side surfaces to further form the wire bundle. After any such re-clamping steps, ultrasonic energy is automatically applied to a second side of the wire bundle, wherein the second side is oppositely disposed relative to the first side. Once again, the sides can be automatically unclamped from the wire bundle. 
         [0008]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0009]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0010]      FIG. 1  is a schematic illustration of an ultrasonic wire welder useful in the methods of the present disclosure. 
           [0011]      FIG. 2  is a schematic illustration of the ultrasonic welder of  FIG. 1  in a wire clamping configuration. 
           [0012]      FIG. 3  is a perspective view of the ends of four stranded wires joined together as a bundle. 
           [0013]      FIG. 4  is a side elevation view of the wire bundle of  FIG. 3  after ultrasonic energy has been applied to one side of the bundle. 
           [0014]      FIG. 5  is a side elevation view of the wire bundle of  FIG. 3  after ultrasonic energy has been applied to opposing sides of the bundle. 
           [0015]      FIG. 6  is a flow chart of an exemplary control method for ultrasonically welding multi-stranded malleable wires together in accordance with the present disclosure. 
       
    
    
       [0016]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0017]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0018]      FIG. 1  illustrates an ultrasonic welder  20  for use in welding multi-stranded wires  22  together. Generally, the ultrasonic welder  20  can include an ultrasonic horn welding tip  24  and a guide block  26  that moves vertically relative to the welding tip  24 . A controller  25  can be programmed to control the movement of the various components of the ultrasonic welder  20 , and the application of ultrasonic energy as described hereinafter. The controller  25  can include a processor and memory (not shown). 
         [0019]    Opposing the welding tip  24  is an anvil  28 . Opposing the guide block  26  is a gather  30 . Bared ends of the wires  22  to be welded together are inserted into the space between the welding tip  24 , the anvil  28 , the guide block  26 , and the gather  30 . Vertical relative movement of the welding tip  24  toward the anvil  28 , and horizontal relative movement of the gather  30  toward the guide block  26 , operates to confine and clamp the bare ends of the wires  22  into a bundle  23  within a welding space  32  as illustrated in  FIG. 2 . 
         [0020]    Exemplary ultrasonic welders  20  are further disclosed in, for example, U.S. Pat. No. 4,782,990, entitled “Portable Gun for Ultrasonically Welding Wires,” which issued to Patrikios et al. on Nov. 8, 1988, and U.S. Pat. No. 4,799,614 entitled “Apparatus for Ultrasonic Welding of Wires,” which issued to Welter et al. on Jan. 24, 1989; both of which are hereby incorporated herein in their entirety. 
         [0021]    The bundle  23  of bare wire ends can, in some cases, be formed from two, three, and four, or more stranded wires  22 .  FIG. 3  illustrates an example wherein four wires  22   a ,  22   b ,  22   c , and  22   d , with bared ends  21   a ,  21   b ,  21   c , and  21   d , respectively, are included in the bundle  23 . 
         [0022]    Referring to  FIG. 6 , the bare wire ends of a plurality of wires  22  to be welded together are positioned between the welding tip  24  and the anvil  28  at box  40 . At box  41 , a user initiates a control sequence programmed into the controller  25  for automatically performing a predetermined welding process. At box  42 , the welding tip  24  can be moved relative to the anvil  28  to contact against opposing sides (e.g., the top and bottom sides in  FIG. 2 ) of the plurality of wires  22 . Similarly, at box  44 , the gather  30  can be moved relative to the guide block  26  to contact against the remaining opposing sides (e.g., the left and right sides in  FIG. 2 ). As a result, the bundle  23  can be gathered and clamped between the welding tip  24  and the anvil  28  on two opposing sides, and between the guide block  26  and the gather  30  on two other opposing sides. 
         [0023]    In some cases, the bundle  23  or nugget can have an area X that is the sum of a side surface area (front in  FIGS. 4 and 5 ) plus the top surface area (top in  FIGS. 4 and 5 ) that is up to about 70 mm 2 , wherein the side surface area is 40% of X and the front surface area is 60% of X. 
         [0024]    An initial amount of ultrasonic energy can be applied via the welding tip  24  against a first side of the bundle  23  at box  46 . At box  47 , the partially-welded wire bundle  23  can be released from the clamping forces of the welding tip  24  and anvil  28 , and the guide block  26  and gather  30 . Then, at box  48 , the movement and operation of the ultrasonic welder can pause to allow the user to rotate the partially-welded wire bundle  23  or nugget 180 degrees as indicated at box  49 . During this pause the partially-welded wire bundle  23  can, in some instances, be allowed to harden. Alternatively or additionally, the partially welded wire bundle  23  or nugget can be automatically rotated 180 degrees via actuators (not shown) under the programmed control of the controller  25 . 
         [0025]    Then the first and second opposing sides of the wire bundle  23  or nugget are again clamped at boxes  50  and  51 , respectively. As a result, the opposing side (which was previously against the anvil  28 ) is now clamped against the welding tip  24 . Thereafter, the ultrasonic welder is programmed to automatically apply a secondary amount of ultrasonic energy can be applied via a welding tip  24  against the opposing side (which was the bottom side in  FIG. 2 ) of the bundle  23  at box  52 . At box  54 , the sides of the finally-welded wire bundle  23  can be unclamped, allowing the wires to be removed from the welder  20 . 
         [0026]    As should be apparent from the above discussion, once the user initiates the control sequence at box  42 , the controller  25  can be programmed to cause the ultrasonic welder  20  to automatically perform any or all of the steps of boxes  42 ,  44 ,  46 ,  47 ,  48 ,  49 ,  50 ,  51 ,  52 , and  54  without any further intervention of the user. In one specific example, the controller  25  can be programmed to cause the ultrasonic welder  20  to automatically perform any or all of the steps of boxes  42 ,  44 ,  46 ,  47 ,  48 ,  50 ,  51 ,  52 , and  54 , without any further intervention of the user other than allowing the user to manually rotate the wire bundle  23  at box  49  during the pause of box  48  or otherwise between box  47  and box  50 . 
         [0027]    An exemplary partially-welded wire bundle  23   a  or nugget in a state and time between box  46  and box  52  is shown in  FIG. 4 . A fully-welded wire bundle  23   b  in a state and time after box  52  is shown in  FIG. 6 . It can be seen in  FIG. 4  that a substantially uniform wire weld is not provided throughout the wire bundle  23   a , while in  FIG. 5  such a substantially uniform wire bundle  23   b  exists. 
         [0028]    In some cases, the ultrasonic weld joint of wire bundle  23   b  can have a tensile pull-out strength measured using a pulling gauge that is at least about 1.5 times that of a weld of identical wires formed by applying the same total ultrasonic energy (i.e., same energy over the same total time period) to just one side of the wire bundle. In other cases, the ultrasonic weld joint can have a tensile pull-out strength measured using a pulling gauge that is at least about 1.7 times that of a weld of identical wires formed by applying the same ultrasonic energy to just one side of the wire bundle. In still other cases, the ultrasonic weld joint can have a tensile pull-out strength measured using a pulling gauge that is at least about 2.0 times that of a weld of identical wires formed by applying the same ultrasonic energy to just one side of the wire bundle. 
         [0029]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
         [0030]    For example, it will be apparent to those skilled in the art that specific details, or that each specifically identified step need not be employed in every method within the scope of this disclosure. Similarly, the employed method steps, processes, and operations do not necessarily require performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0031]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0032]    Spatially relative terms, such as “upper,” “lower,” “top,” “bottom,” “sides,” “left,” “right,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “lower” or “bottom” relative to other elements or features would then be oriented as “upper” or “above” the other elements or features. Thus, the example term “upper” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.