Patent Publication Number: US-10770856-B2

Title: Bent electric contact element with chamfered edges and method for its manufacture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of European Patent Application No. 17196663.3, filed on Oct. 16, 2017. 
     FIELD OF THE INVENTION 
     The present invention relates to an electric contact element and, more particularly, to a bent electric contact element. 
     BACKGROUND 
     Using current manufacturing processes, electric contact elements do not keep their exact orientation after being bent. Thus, the actual location of a contact portion of the contact element, such as a pin or tab section, may differ from the desired location. If a plurality of parallel electric contact elements is manufactured from a strip of previously interconnected electric contact elements in the blank, a pairing effect is often observed where a pair of adjacent electric contact elements lean towards each other, leaving alternatingly smaller and larger gaps between the contact portions. Due to the drive towards miniaturization of electric connections, such deviations of the actual position of the contact section from the desired or prescribed position is not tolerable. 
     SUMMARY 
     An electric contact element comprises a bent portion. The bent portion has a cross-section with a corner that has a chamfer at least in the bent portion. 
    
    
     
       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 a perspective view of a blank consisting of a strip of unbent electric contact elements; 
         FIG. 2  is a sectional side view of an electric contact element after cutting; 
         FIG. 3  is a sectional side view of the electric contact element after forming a chamfer; 
         FIG. 4  is a side view of a process of bending the electric contact element; and 
         FIG. 5  is a perspective view of a bent portion of the electric contact element. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     Embodiments of the present invention will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to the like elements. The present invention 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 disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. 
     A strip  1  of electric contact elements  2  is shown in  FIG. 1 . The strip  1  has been stamped from a sheet material containing or consisting of a metal such as copper or any other electrically conductive material. This allows production of the electric contact elements  2  at a high rate by forming the strip  1  of interconnected electric contact elements  2  simultaneously as a blank  3  from the sheet metal in a die. 
     The strip  1  shown in  FIG. 1  constitutes the blank  3  and not the final product, the electric contact elements  2  are separated from each other in the final product. The shape of the electric contact elements  2  shown in  FIG. 1  is merely exemplary and is not to be construed as limiting. In an embodiment, the electric contact elements  2  each have a male or female contact section  4  at either of their free ends. The disclosure herein also relates to an electric contact element  2  which is not formed as part of a strip  1 . 
     The strip  1 , as shown in  FIG. 1 , may be used for header pins and tabs and, in the shown embodiment, is bent about an axis  6  which extends perpendicular to a longitudinal direction  8  of the electric contact element  2 . In the embodiment of the strip  1  shown in  FIG. 1 , the longitudinal directions  8  of all electric contact elements  2  are parallel to each other. The longitudinal direction  8  is determined by the elongated shape of the electric contact element  2 , where the dimension along the longitudinal direction  8  is significantly larger than the other two perpendicular dimensions. 
     If the electric contact elements  2  are bent about axis  6 , it is important that they do not lose their relative orientation, for example, that they remain parallel to each other, and that the contact sections  4  after bending are located within a pre-determined position tolerance. 
     In  FIGS. 2 and 3 , a cross-section  10  of an electric contact element  2  perpendicular to the longitudinal direction  8  at the position of the axis  6  is shown.  FIG. 2  shows the cross-section  10  right after cutting the electric contact element  2  from the metal sheet (not shown). Cutting is performed by two shearing knives  12 , which are shown schematically in  FIG. 2 . The shearing knives  12  are moved along a cutting direction  14  to separate the contact element  2  from the surrounding sheet. The rectangular cross-section  10  shown in  FIG. 2  results from the cutting by the shearing knives  12 . The sides  16  along which the separation takes place are sheared off from the surrounding material. 
     The shearing leaves a typical structure of the sheared sides  16  shown in  FIG. 2 . A roll-over section  18  is characterized in the cross-section  10  by material which is plastically drawn by the shearing knife  12  in the cutting direction  14  when the shearing edge  12  enters the material. The roll-over section  18  is recognizable by a radius-like shape, which, however, may vary depending on the wear of the sheared edge  12 , its angles, and the cutting velocity. Following the roll-over section  18 , there is a burnish section  20 , where the material is clearly sheared off. The burnish section  20  is comparatively smooth and extends almost planarly in the cutting direction  14 . 
     As shown in  FIG. 2 , following the burnish section  20  in the cutting direction  14  is a fracture section  22  which is caused by material, which is not cut, but breaks off due to excessive stress generated by the shearing edges  12 . The fracture section  22  is less planar and rougher than the burnish section  20 . Finally, the sheared side  16  terminates in the cutting direction  14  in a burr  24 . The roll-over section  18 , burnish section  20 , fracture section  22 , and burr  24  are all invariably present in an electric contact element  2  which has been formed by shearing. The exact relative lengths of these four section, however, may vary. 
     Although the structure of a sheared side  16  has been explained in  FIG. 2  only with reference to the left-handed side of the cross-section  10  depicted therein, any other sheared side  16 , such as the sheared side on the right-hand side, has the same general structure. 
     A bending process of the electric contact element  2  becomes more accurate if at least one of the corners  26  is chamfered. The chamfer  32 , shown in  FIG. 3 , has a chamfer width  30  that extends over at least 10% of the nominal width  28  of the contact element  2 , where both widths  28 ,  30  are measured in the same direction. In various embodiments, the chamfer  32  is inclined between 30° and 60°, or around 45°, relative to at least one of the adjacent sides. 
     Better bending results have been obtained if the chamfer  32  is formed in the fracture section  22 , i.e. if the formation of the chamfer  32  is used for deburring or removing the burr  24 . 
     In an embodiment, the chamfer  32  is formed by plastic deformation, in particular by stamping, for example by pressing a swage  34  against the respective corner  26  as shown in  FIG. 3 . The motion direction  36  of the swage  34  may be inclined with respect to both sides  16 ,  38  which are joined by the corner  26 . In various embodiments, the motion direction  36  may be inclined between 30° and 60°, or around 45° with respect to any of the sides  16 ,  38 . The chamfer  32  is thereby disposed at an end of the fractured section  22  of the sheared side  16 . 
     As shown in  FIG. 3 , a chamfer  32  may be formed wherever a burr  24  has been formed by the preceding cutting operation. A further improvement of the accuracy of the bending of the contact element  2  may be achieved when at least one side  38  of the cross-section  10  is plastically flattened. This can be achieved by moving another swage  40  against the side  38  in a direction  42  that is perpendicular to the side  38  which is to be flattened. The swage  40  covers all of the side  38  at least in a direction perpendicular to the longitudinal direction  8 . 
     Positioning the contact sections  4  after bending within tight tolerances has been achieved when the flattened surface is located opposite the at least one chamfer  32  as shown in  FIG. 3 . The flattened surface  38  does not need to border a chamfer  32 . The swages  34 ,  40  need only to extend in the longitudinal direction  8  along the portion of the contact element  2  that will be bent in the next step or one of the subsequent steps. They do not need to extend also along sections which will not be bent. 
     After the at least one chamfer  32  has been formed and, optionally, the side  38  has been flattened, the electric contact element  2  is bent about axis  6 , for example, by 90°. In other embodiments, other bending angles are also possible. The accuracy of the bending is improved if the at least one chamfer  32 , or two chamfers  32  as shown in  FIG. 3 , are at the radially outward-facing side  43  in the bent portion, as shown in  FIG. 4  where the bending direction  44  is indicated by an arrow. The flattened side  38  forms the radially inward-facing side  45  at the bent portion of the electric contact element  2 . 
       FIG. 5  shows the bent portion  46  of an electric contact element  2 . The chamfer  32  extends at least along the bent portion  46  in the longitudinal direction  8 . The flattened side  38  is opposite the chamfer  32  at the radially inward-facing side of the bent portion  46 . The at least one chamfer  32  and the flattened side  38  improve the accuracy of the bending process, especially when a plurality of electric contact elements  2 , which may in particular be parallel to each other along respective linear portions  33 , are bent simultaneously so that maintenance of the parallel orientations is maintained. Further, as shown in  FIG. 5 , the electric contact element  2  may be part of an electric connector  48 , such as a header.