Patent Publication Number: US-2023155336-A1

Title: High Deformation and Retention Ferrule

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to electrical ferrules, and more specifically, to an open type, crimpable ferrule. 
     BACKGROUND 
     Ferrules are commonly used to crimp cables onto connectors. Closed tube (i.e., seamless) ferrules typically provide much stronger cable retention and improved electrical performance compared to open type ferrules. However, closed tube ferrules are much more costly to manufacture, and more difficult to apply and crimp to a cable. Conversely, open type or U-shaped ferrules are more efficient to manufacture and assemble to the cable, but are typically weaker in cable retention compared to their tube type counterparts. Sufficient electrical shielding performance may also be more difficult to obtain with open type ferrules, as their designs typically expose cable braiding as compared to the closed tube ferrules which completely contain or cover the cable braid over their length. Incomplete closure of the ferrule is often seen along the joining seems as well, particularly due to insufficient spring-back resistance. The resulting exposed braid is a significant issue, as the potential for electrical shorting is much higher. 
     Accordingly, improved open type, crimpable ferrules are desired which address these shortcomings, while remaining cost effective to manufacture and assemble. 
     SUMMARY 
     In one embodiment of the present disclosure, a cable assembly comprises a conductive cable including an exposed conductive first section having a first cross-section, and a second section adjacent the first second and having a second cross-section distinct from the first cross-section. A ferrule is positioned over the conductive cable and includes a body defining a seam formed therethrough in an axial direction. The ferrule further includes a first body portion deformed into a cross-section corresponding to the first portion of the conductive cable, and a second body portion deformed into a cross-section corresponding to the second portion of the conductive cable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying Figures, of which: 
         FIG.  1    is perspective view of a ferrule according to an embodiment of the present disclosure in a crimped or closed state; 
         FIG.  2    is a perspective view of the ferrule of  FIG.  1    in a pre-crimped or open state; 
         FIG.  3    is a front view of the ferrule of  FIG.  2    in the pre-crimped or open state; 
         FIG.  4    is a top view of the ferrule of  FIG.  1    in the crimped state on a cable assembly; 
         FIG.  5    is a perspective view showing a joining seam of a ferrule according to an embodiment of the present disclosure; 
         FIG.  6    is a perspective view of a ferrule according to an embodiment of the preset disclosure in a pre-crimped or open state; 
         FIG.  7    is a perspective view of the ferrule of  FIG.  6    in a crimped or closed state; and 
         FIG.  8    is a perspective view of a ferrule according to an embodiment of the present disclosure in a pre-crimped or open state. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will convey the concept of the disclosure to those skilled in the art. In addition, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it is apparent that one or more embodiments may also be implemented without these specific details. 
     Embodiments of the present disclosure include a U-type ferrule and a method of use thereof. The ferrule is adapted to be crimped into an O-type ferrule with a varying overall diameter in the form of a material plastic deformation altering the general diameter and thickness of the ferrule in at least one area along its axial length. In this way, one portion of the ferrule may be formed to the shape of, for example, a cable jacket or other component of a cable assembly (e.g., a connector component), while another portion of the ferrule may be securely fastened to exposed internal braiding or conductor(s) of the cable. The deformation of the ferrule prevents spring-back of the closed ends, improving retention and shielding characteristics, as well as minimizing the risk of other failures, such as electrical shorting. 
       FIG.  1    shows a ferrule  100  according to an embodiment of the present disclosure in a closed or crimped state or position. In the closed position, a body  105  of the ferrule  100  defines a generally hollow tapering cylindrical and/or partially tapering hollow cylindrical shape. The body  105  is formed from respective first and second sidewalls  120 , 130  extending from a curved base  110 . More specifically, through a crimping, stamping, or other processing, the body  105  is plastically deformed into the illustrated form, with the base  110  and sidewalls  120 , 130  curved into the generally cylindrical shape shown. The resulting opposing free edges or ends  140 , 142  of the sidewalls  120 , 130  abut continuously along the length of the ferrule  100  so as to define a closed or generally closed seam  150 . 
     The exemplary body  105  defines a first portion or section  160  having a generally hollow cylindrical cross-section of a first inner and/or outer diameter. A second portion  170  extends continuously from the first portion  160  and defines a tapering hollow cylindrical cross-section of a tapering or varying inner and/or outer diameter. A third portion  180  of the body  105  extends continuously from the second portion  170  and defines another hollow cylindrical cross-section of a second inner and/or outer diameter, greater than the first diameter of the first portion  160 . The first, second and third portions  160 , 170 , 180  of the body  105  define a coaxial central opening  200  extending in a longitudinal or axial direction of the ferrule  100  and/or a cable associated therewith. 
     As the body  105  is deformed during crimping, the first section  160  is compressed radially inward under a force greater than that of the third section  180 . As a result, a material thickness T 2  of the circumferential sidewall of the first section  160  is increased, or is greater than, a thickness T 1  of a remainder of the body  105  (i.e., than a thickness of the entire original material thickness of the uncrimped ferrule or stock). In this way, the formation of the portions  160 , 170 , 180  includes more than a mere alteration of the exterior dimensions (including the length) of the ferrule, but further alters the in-plane thickness of the base material in the first section. 
     Referring to  FIGS.  2  and  3   , the ferrule  100 ′ is shown in an open state, prior to crimping or other forming operations. As shown, the body  105  of the ferrule  100 ′ comprises a generally U-shaped profile or cross-section defined by each of the sidewalls  120 , 130  extending outwardly and obliquely from a respective side of the base  110 . The cross-section of the body  105  is continuous and uniform along its axial length. More specifically, the axial lengths of the base  110  and walls  120 , 130  are uniform or equal, as are the height of each of the sidewalls  120 , 130 . The body  105  may be formed by processing a single sheet of conductive material, such as copper of a uniform thickness T 1 . The edges or ends  140 , 142  of each of the walls  120 , 130  may each define a first chamfer C running the longitudinal or axial length of each edge, and/or chamfers C′ formed transverse to the axial direction at each corner of the walls  120 , 130 . The chamfers C,C′, and specifically the chamfers C may aid in the retention of the walls  120 , 130  in the abutting manner shown in  FIG.  1   , resisting the opening or spring-back of the ferrule  100  after crimping or formation. In other embodiments, as shown in  FIG.  8   , the uncrimped ferrule  100 ″ may be comprise a non-uniform cross-section. More specifically, the ferrule  100 ″ may generally be defined by two U-shaped cross-sections  160 , 180  of differing sizes joined by a middle tapering section  170 . As described above, despite the varying cross-section, in the uncrimped state, the ferrule  100 ″ comprises a uniform thickness T 1 . The formation of the ferrule  100 ″ with a non-uniform cross-section is advantageous in that it may be more closely fit to a cable jacket and/or cable internal cable shield or conductor prior to a crimping operation. The remaining features of the ferrule  100 ″ are common to the uniform ferrule  100 ′, and the crimped ferrule  100 , and therefore will not be described further. 
     Referring now to  FIG.  4   , the closed ferrule  100  is shown in use with, or as part of, a cable assembly  50 . The cable assembly  50  may include a cable  10  having at least an outer (or intermediate) jacket  15 , as well as at least one internal conductor  20 , such as a multi-strand braided central conductor. As shown, the conductor  20  has been exposed via a removal of the jacket  15  in at least one area. In the exemplary embodiment, the cable  10  was inserted into an open ferrule (ferrule  100 ′), and the ferrule crimped (e.g., in a die) or otherwise plastically deformed to form the first, second and third portions  160 , 170 , 180  of the body  105 . As shown, at least the first portion  160  of the body  105  corresponds in inner diameter to an outer diameter of the conductor  20 , and has been deformed to the exemplary thickness T 2 . In this way, the ferrule  100  tightly holds and establishes reliable electrical contact with the conductor  20 . Likewise, the ferrule  100  is firmly held in place by the third portion  180  of the body  110 , which corresponds in inner diameter to an outer diameter of the jacket  15 . The stepped nature defined by the second portion  170  of the body  110  aids in preventing the axial translation of the ferrule  100  along the cable  10 . Further, the deformation defined by the second portion  170  improves resistance against the ferrule opening or springing-back to an at least partially opened state after crimping. As shown, the seam  150  is uniformly closed along the length of the body  105 . In other embodiments, the third portion  180  may be used to attach to an internal portion of a cable (e.g., a shield or a conductor) which has a greater diameter than a jacket of a cable connected to first portion  160 . 
     Referring to  FIG.  5   , in an embodiment of the present disclosure, the free edges  140 , 142  of the body of the ferrule  100  may define engaging or corresponding protrusions and recesses extending along the longitudinal length of each of the sidewalls of the ferrule  100 . Specifically, the exemplary edge  140  may define a protruding lip  141  extending in the circumferential direction and into a corresponding recess  143  formed in the opposing sidewall edge  142 . As illustrated, both the protrusion or lip  141  and recess  143  extend in the longitudinal direction over the length of the ferrule, and are offset in the radial direction with respect to one another. In this way, the closed ferrule  100  can maintain a uniformly circular outer profile and maximize the closure of the seam  150 . This arrangement may also improve braid retention of the ferrule when used with stranded conductors. 
     It should be understood that the ferrules according to embodiments of the present disclosure may be fitted to other types of components having other shapes without departing from the scope of the present invention. For example, referring to the embodiment of  FIGS.  6  and  7   , another ferrule  300 , 300 ’ is shown. In the open state shown in  FIG.  6   , the ferrule  300 ′ comprises a U-shaped body  305  having a base  310  and two sidewalls  320 , 330  similar to those set forth above with respect to the ferrule  100 , 100 ’. In the exemplary embodiment, however, the ferrule  300 ′ may be configured to secure on a first end to a pair of electrical connectors or terminals, or to a single connector or terminal configured to hold two conductors. This may be enabled by forming (e.g., stamping) a pair of recesses or channels  360  into the base  310 . In the exemplary illustrated embodiment, the formation of the channels  360  results in the presence of an arcuate rib  362  extending in the axial direction. The channels  360  extend axially into the base  310  to a depth D corresponding, for example, to a desired depth of a terminal or connector to be captured by the ferrule  300 ′. 
     The ferrule  300  is illustrated in the closed or crimped state in  FIG.  7   . On a first end of the ferrule  300 , the portion of the ferrule associated with the channels  360  extending to the depth D has been plastically deformed to correspond in shape or cross-section to an electrical terminal or connector  390  defined by at least two semi-circular bodies. On an opposite or second end of the ferrule  300  (i.e., corresponding to the third portion  180  of the ferrule  100 ), the sidewalls  320 , 330  have been deformed into a corresponding generally cylindrical shape for securing to a cable or cable jacket  380 . An intermediate or central portion  370  of the ferrule  300  forms a continuous transitional profile between the first and second ends. Despite the distinction cross-sections of the first and second ends, the controlled crimping or deformation processing has maintained a closed seam  350  over the axial length of the ferrule  300 , improving electrical shielding, and overall mechanical stability of the ferrule. 
     In view of the above-described embodiments, a method of forming a ferrule for use with a cable or cable assembly is also provided. The method includes the steps of fitting a conductive cable into an uncrimped ferrule. The uncrimped ferrule comprises a generally uniform U-shaped cross-section, as shown throughout the figures. In one or more crimping steps, a first section of the ferrule is crimped into a cross-section corresponding to a first cross-section of a first section of the cable, and a second section of the ferrule is crimped into a cross-section corresponding to a second cross-section of a second section of the cable, distinct from the first cross-section. Either through the crimping steps, or through a separate closing step, opposing edges of the ferrule are abutted along a longitudinal or axial direction of the cable (or ferrule) for closing the ferrule continuously about its circumference and along its length. 
     The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range. 
     Also, the indefinite articles “a” and “an” preceding an element or component of the invention are intended to be nonrestrictive regarding the number of instances, that is, occurrences of the element or component. Therefore “a” or “an” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular. 
     The term “invention” or “present invention” as used herein is a non-limiting term and is not intended to refer to any single embodiment of the particular invention but encompasses all possible embodiments as described in the application.