GB2071529A - A method of forming pin contact members - Google Patents

Abstract

A method of forming a pin contact member for micro-miniature connectors and of the kind comprising at least one length of resilient wire bent to form an elongated loop is described. The length of wire (10) is located over the nose (15) of a plunger (16). The plunger (16) is then moved through a bore (21) to bend the wire over the nose (15) and down the sides of the plunger to form the closed end and the limbs of an elongated loop. Thereafter the limbs of the loop are secured relatively to each other for example by a crimped on ferrule (26). <IMAGE>

Description

SPECIFICATION Fabrication of pin contact members of pin and socket connectors This invention relates to methods of fabricating pin contact members of pin and socket connectors.

In particular the invention is concerned with pin contact members used in micro-miniature connectors and of the kind comprising at least one length of resilient wire bent to form an elongated loop with the limbs of the loop located together for example by crimping within a ferrule and with the closed end of the loop constituting the leading end of the pin contact member. In use such pin contact members are normally located in a bore for example of a contact block and a cooperating socket member is pushed into the bore and over the pin contact member which then resiliently engages the inner surface of the cooperating socket member.

According to the present invention, in a method of forming a pin contact member of the kind described at least one length of wire is located on the nose, i.e. the leading end, of a plunger, the plunger is then moved through a bore to bend the wire over the nose and down the sides of the plunger to form the closed end and the limbs of the loop, the wire is then held in the bore while the plunger is withdrawn and thereafter the limbs of the loop are secured relatively to each other.

Preferably said pin contact member is formed by a plurality of said loops disposed at an angle to each other about the longitudinal axis of the pin contact member. In fabrication of such a pin contact member, a plurality of lengths of wire are located on the nose of said plunger at the desired angle to each each other so that the closed ends and limbs of the loops are formed simultaneously when said plunger is moved through said bore, and the limbs of all said loops are then simultaneously secured relatively to each other after the withdrawal of said plunger.

The invention will now be further explained by way of example with reference to the accompanying drawings, in which: Figure 1 shows the kind of micro-miniature pin contact member with which the invention is concerned, Figure 2 is a view looking in the direction of arrow II of Figure 1, and Figure 3 is a diagrammatic sectional view of the apparatus used for carrying out the method of the invention in accordance with one example.

Referring now to Figures 1 and 2, the pin contact member 1 is housed in bore 2 of a contact block 3, which also houses a plurality of further similar pin contact members in respective bores.

The pin contact members simultaneously cooperate with respective socket contact members mounted in a connector block when the two connector blocks are brought together.

Each pin contact member 1 comprises two elongated wire loops 4 and 5, the limbs of the loops 4 and 5 being crimped together through ferrule 6 which is fixedly located in the bore 2. The free ends of the limbs of the loops 4 and 5 extend beyond the ferrule 6 to provide tails 7 for making an electrical connection with an associated circuit.

The wire loops 4 and 5 comprise for example .09 mm berryllium copper wire which is gold plated.

The resilience of the wire is such that due to the bending deformation at the closed ends of the loops and the drawing together of the limbs of the loops at the crimp the limbs of the loops bow out as shown in Figure 1 to contact the surface of the bore 2. A cooperating socket contact member is of tubular form and is designed to be a close fit in the bore 2. Thus when the socket contact member is pushed into the bore 2 it passes over the closed ends of the loops 4 and 5 and between the surface of the bore and the limbs of the loops 4 and 5. The loops are therefore deformed inwardly so that they resiliently engage the socket contact members. A connector of this form forms the subject of our Patent Application No.

7929632 (Serial No. 2028603).

Referring now to Figure 3, the method of fabricating a pin contact member 1 of the form shown in Figures 1 and 2 will now be described.

The first step in the method is to feed two lengths of wire 10 and 11 from respective reels into the apparatus; before entering the apparatus the wires are straightened to obviate their subsequent tendency to twist. This wire feeding is achieved using reciprocating wire-feed tubes 1 3 whose paths of movement are at right angles to each other. Only the viire-feed tube 1 3 for the wire 10 is visible in Figure 3. The forward stroke of the wire-feed tubes delivers the leading ends of the two lengths of wires 10 and 11 across the underside of form bed 14 and over the nose 1 5 of form plunger 16.The leading ends of the wires 10 and 11 are then clamped against the underside of form bed 1 4 by respective wire clamps 1 7 and thereafter the return stroke of the wire feed tubes 13 is carried out so that at the end of the return stroke the wires 10 and 11 are held in tension between the clamps 1 7 and the wire-feed tubes 13.

Plunger 1 6 is then advanced towards the wires 10 and 11 so that the wires locate in respective grooves 18 extending at right angles to each other across the nose of the plunger 1 6. Each groove 1 8 continues down the sides of the plunger 1 6 to sloping annular shoulder 19 on the plunger 16, the base of the groove being curved in crosssection and extending over the nose 1 5 of the plunger in a convex curve which merges smoothly with the portions of the groove extending down the sides of the plunger.

Cutters 20 are advanced to cut the wires 10 and 11 and are then retracted and the wire clamps 1 7 are released. The plunger 1 6 is then advanced through bore 21 in the form bed 14 and into bore 22 of re-usable carrier 23 until its sloping shoulder 19 engages the form bed to trap the wires 10 and 11 against the form bed around the periphery of the bore 21. Thus the wires 10 and 11 are formed into elongated loops with the closed ends of the loops being formed over the nose 15 of the plunger 16 and the limbs of the loops extending in the portions of the grooves 1 8 down the sides of the plunger 1 6.

Thereafter the pre-crimp clamp 24 is moved along the plunger 16 to clamp the wires 10 and 11 against the underside of the form bed 14. The plunger 1 6 is then retracted sufficiently to clear crimp jaws 25. Ferrule 26 is then fed by a ferrule injector 27 down through the bore 22 of the carrier 23 and over the formed wire loops to align with the crimp jaws 25 and the crimp jaws 25 are then advanced to form for example a square crimp and are then retracted. Plunger 1 6 is then advanced sufficiently to push the completed pin contact member fully home in the carrier 23 and is then retracted to its starting position ready for the next operating cycle.

The carrier 23 has a line of bores 22 and is movable in steps to bring each of the bores 22 in turn in alignment with the bore 21 in the form bed 14. Thus after the retraction of the plunger 1 6 to its starting position the carrier is moved one step to the right as shown in Figure 3 to align its next bore 22 with the bore 21 in the form bed 14.

Although not shown in Figure 3, the re-usable carrier 23 may advantageously be of sufficient thickness to completely house the pin contact members down to and including the ferrule 26 when they have been pushed fully home by the plunger 16.

In a first modification of the above described method the ferrule injector 27 may have slots 28 extending at right angles to each other as shown in Figure 3 so that the formed wire loops at their closed ends locate in these slots when the injector is advanced to hold the loops and maintain their 90 relationship. The wires can then be cut at the level of the crimp jaws 25 before the ferrule 26 is fully home, thereby leaving a clear solder bucket within the lower end of the ferrule 26.

In a second modification, the carrier 23 can in fact be constituted by the pin contact block in which the pin contact members are finally mounted.

Claims (13)

1. A method of forming a pin contact member of the kind described, wherein at least one length of wire is located on the nose of a plunger, the plunger is then moved through a bore to bend the wire over the nose and down the sides of the plunger to form the closed end and the limbs of an elongated loop, the wire is then held in the bore while the plunger is withdrawn and thereafter the limbs of the loop are secured relatively to each other.

2. A method according to Claim 1, wherein the length of wire locates in a groove in the nose of the plunger, said groove extending convexly over the nose and being concave in cross-section.

3. A method according to Claim 2, wherein said groove in the nose of the plunger merges smoothly with grooves extending down the sides of the plunger and in which the portions of the length of wire forming the limbs of the loop locate.

4. A method according to any preceding claim, wherein the length of wire is first fed across the path of movement of said plunger and is held in tension as said plunger is moved to locate the wire on its nose.

5. A method according to any preceding claim, wherein said plunger has a shoulder spaced from its nose and said plunger is moved through said bore until said shoulder engages the adajcent end of said bore to trap said wire between said shoulder and the periphery of the bore.

6. A method according to Claim 5, wherein after said wire has been trapped a pre-crimp clamp is moved along the plunger to trap the wire ends against a surface surrounding the adjacent end of said bore.

7. A method according to Claim 6, wherein said bore is provided in a form bed and a carrier is spaced from said form bed and has a bore aligning with the bore in said form bed and into which carrier bore the nose of the plunger passes after passing through the bore in the form bed, and wherein after said wire ends have been trapped by said pre-crimp clamp said plunger is retracted to clear the space between said form bed and carrier, a ferrule is passed over the closed end of the loop and along the limbs of the loop to a position in which it is located in the space between the form bed and carrier and crimp jaws located in said space are operated to form a crimp on said ferrule to locate the limbs of the loop relatively to each other.

8. A method according to Claim 7 wherein said ferrule is passed over the closed end of said loop by a ferrule injector having means for locating the closed end of the loop to hold it in position and the free ends of the wire are cut away before the ferrule is fully in position, whereby after crimping the cut ends of the length of wire are located within the ferrule.

9. A method according to Claim 7 or 8, wherein after operation of the crimping jaws the plunger is then advanced again to push the closed loop and ferrule into the carrier and is then retracted to its starting position for the next operation.

10. A method according to Claim 7, 8 or 9 wherein the carrier has a plurality of bores and after the plunger has been retracted to its starting position the carrier is moved to bring another empty bore into alignment with the bore of said form bed.

11. A method according to Claim 10, wherein said carrier comprises a pin contact block in which the pin contact members are mounted for use.

12. A method of forming a pin contact member according to any preceding claims, wherein a plurality of lengths of wires are located on the nose of the plunger and extend at an angle to each other across the nose, the lengths of wire being simultaneously and similarly operated upon at each stage of the method.

13. A method of forming a pin contact member of the kind described substantially as hereinbefore described with reference to the accompanying drawings.