Method of fabricating contact strips for electrical device connectors

Abstract

Contact strips are obtained by segmenting a secondary strip of contacts fabricated from a metal ribbon in which openings are formed with an original regular pitch to form a discontinuous central strip of blades. Each blade is twisted to produce a primary contact strip. The method further includes pleating the primary strip and a hardening heat treatment, and begins with the following operations: the ribbon is metal-plated on both sides to cover at least the central strip with a layer of a metal that is a good electrical conductor, openings are formed in the ribbon, and each blade is twisted. It then includes the following successive operations: the primary strip is pleated, the hardening heat treatment is then applied to produce the secondary contact strip, and the secondary strip is segmented into a plurality of contact strips.

What is claimed:  
     
         1 . A method of fabricating contact strips for electrical device connectors by segmenting a secondary strip of contacts fabricated from a metal ribbon in which openings are formed with an original pitch to form a discontinuous central strip of blades whose longitudinal ends are attached to two continuous edge strips of said ribbon and each of said blades is twisted about its longitudinal axis to pivot relative to the plane of said ribbon and bent so that each of its two faces has at least one projecting area to form a contact on one side of said plane, said twisting and bending producing a primary contact strip whose blades are spaced at substantially the same regular pitch as the original pitch of said openings, said method further including pleating said primary contact strip by forming pleats on each continuous edge strip to move said blades closer together, and a hardening heat treatment to impart hardness to said blades combined with some elasticity so that they function as springs, and which method begins with the following three steps: 
 a) said ribbon is metal-plated on both sides to cover at least said central strip with a layer of a metal that is a better electrical conductor than the metal of said ribbon,    b) said openings are formed in said ribbon, and    c) each of said blades is twisted and bent, and then includes the following successive operations:    d) said two continuous edge strips of said primary strip of contacts are pleated,    e) said hardening heat treatment is applied to the contact strip obtained after the foregoing operations, to produce said secondary contact strip, and    f) said secondary contact strip is segmented into a plurality of contact strips ready to be mounted on the connectors for which they are intended with a strip length as required for each connector.    
     
     
         2 . The fabrication method claimed in  claim 1 , wherein said ribbon is metal-plated by galvanization.  
     
     
         3 . The fabrication method claimed in  claim 1 , wherein all of the surface of said ribbon is covered during the metal-plating operation.  
     
     
         4 . The fabrication method claimed in  claim 1 , wherein said ribbon is metal-plated before said openings are punched in the ribbon.  
     
     
         5 . The fabrication method claimed in  claim 1 , wherein, during said pleating operation, said blades are moved closer together so as to be regularly spaced with a new regular pitch such that the ratio between the original pitch and the new pitch is from 1.3 to 2.  
     
     
         6 . The fabrication method claimed in  claim 5 , wherein said pleats are formed in two continuous edge strips of the ribbon on the same side of the plane of the ribbon and each pleat has a height such that the ratio between the new regular pitch and said height is from 1.7 to 2.5.  
     
     
         7 . The fabrication method claimed in  claim 6 , wherein each pleat is formed with a transverse cavity whose section in the longitudinal direction has straight portions and portions with a substantially constant radius of curvature and the bottom of said cavity has a curvature diameter such that the ratio between the height of a pleat and the diameter is from 2.4 to 3.2.  
     
     
         8 . A contact strip for connecting a medium-voltage or high-voltage electrical device, obtained from a metal ribbon in which openings are made to form a discontinuous central strip of blades and the whole of the surface of said contact strip is plated with a layer of a metal that is a good electrical conductor, longitudinal ends of said blades are attached to two continuous edge strips of said ribbon that are bent with transverse bends and said blades are regularly spaced with a regular pitch, in which contact strip said pleats protrude from the same side of the plane of said ribbon and each pleat has a height such that the ratio between said regular pitch and said height is from 1.7 to 2.5.  
     
     
         9 . The contract strip claimed in  claim 8 , wherein each pleat is formed with a transverse cavity whose section in the longitudinal direction has straight portions and portions with a substantially constant radius of curvature and the bottom of said cavity has a curvature diameter such that the ratio between the height of a pleat and the diameter is from 2.4 to 3.2  
     
     
         10 . The contact strip claimed in  claim 8 , formed by A method of fabricating contact strips for electrical device connectors by segmenting a secondary strip of contacts fabricated from a metal ribbon in which openings are formed with an original pitch to form a discontinuous central strip of blades whose longitudinal ends are attached to two continuous edge strips of said ribbon and each of said blades is twisted about its longitudinal axis to pivot relative to the plane of said ribbon and bent so that each of its two faces has at least one projecting area to form a contact on one side of said plane, said twisting and bending producing a primary contact strip whose blades are spaced at substantially the same regular pitch as the original pitch of said openings, said method further including pleating said primary contact strip by forming pleats on each continuous edge strip to move said blades closer together, and a hardening heat treatment to impart hardness to said blades combined with some elasticity so that they function as springs, and which method begins with the following three steps: 
 a) said ribbon is metal-plated on both sides to cover at least said central strip with a layer of a metal that is a better electrical conductor than the metal of said ribbon,    b) said openings are formed in said ribbon, and    c) each of said blades is twisted and bent, and then includes the following successive operations:    d) said two continuous edge strips of said primary strip of contacts are pleated,    e) said hardening heat treatment is applied to the contact strip obtained after the foregoing operations, to produce said secondary contact strip, and    f) said secondary contact strip is segmented into a plurality of contact strips ready to be mounted on the connectors for which they are intended with a strip length as required for each connector.