Patent GB-935478-A (GB)
Title: Method of and automatic machine for producing resilient plug or socket contacts
IPC: H01R43/00
Filed: 1962-07-23
Abstract: 935,478. Making contacts; jointing by stamping; end capping rods. O. DUNKEL. July 23, 1962 [July 24, 1961], No. 28215/62. Classes 83 (2) and 83 (4). A method of making resilient contacts, e.g. plugs and sockets comprising a central supporting pin and resilient contact elements in the form of pieces of wire distributed around the supporting pin comprises clamping the support pin, feeding wire from a number of reels, cutting the wire into suitable lengths and fixing them on the support pin. A support pin 2 is held by clamping elements 1 actuated by a cam-controlled linkage at the base of an automatic machine comprising a mandrel 7 having a bore 8 to engage the pin head 6. Wire 10 is fed from reels 9 to the pin 2 along the surface of the mandrel and through rings of nozzles 11, 12, 13 mounted on holding devices 14, 15. A number of hydraulic or pneumatically-operated plungers 16, 17 corresponding in number to the number of wires 10 are horizontally mounted inside the holder devices 14, 15 and a coaxially movable wirecutting device 20 comprising cutters 21 located below the device 15. The device 14 is movable coaxially to the mandrel to advance the wire stepwise. Tapered bores 24 situated beneath the cutters 21 facilitate the introduction of the cut pieces of wire 22 into a retaining ring 26 positioned concentrically about the foot 25 of the pin. The ring 26 and wires 22 are pressed about the beading 33 of the foot of the pin by elements 29, 30 slidably actuated by the tapered walls 28 of a recess 27 formed in the underside of the device 20 engaging the tapered ends 31 of the elements during the downward movement of the device 20. In operation, the plungers 17 release the wires, the plungers 16 engage the wires and the holder 14 moves downwardly to feed the wires into the ring 26, the plungers 16 release the wires which are then re-engaged by the plungers 17, the holder returns to its starting position, the cutters 21 sever the wires and the device 20 moves downwardly to effect the pressing of the wires and the ring to the pin. The assembly is subsequently transferred to a pre-shaping device comprising a support mandrel 35 which carries a resilient shaping head 37, preferably of a plastic material. A pair of shaping elements 38, 39, having shaped forms complementary with those of the head 37 and inclined surfaces 40, 41 are actuated transversely to form the wires about the head 37 by a coaxially movable element 44 having co-operating inclined surfaces 42, 43. The assembly is transferred to a capping device comprising transversely slidable clamping elements 49, 50 having inclined surfaces which co-operate with elements 47, 48 to depress the wires 22 until their free ends engage a groove 53 beneath the head of the pin. Caps 4 are fed along a horizontal conveyer to a vertical conveyer 56 having rubber projections 57 which feed them down a vertical surface 58 to the pin 2. A cap is positioned on the head of the pin 2 and notched thereto by a number of plungers 59 arranged around the periphery of the head. The cap thereby retains the ends of the wires within the groove so that they are freely displaceable in the longitudinal direction. The finished plug is finally transferred to a device for simultaneously checking the plug in force and contact resistances. The device comprises a plunger 60 fitted over the plug, which is connected to a dynamometer 62 having contacts 64, 65 and an adjustable co-operating pointer 63. The contacts are in a D.C. circuit 66 which can be closed by the pointer 63, followed by a delay action relay 67. On movement of the plug within the bore 61 the circuit is closed if the tolerance determined by the position of the contacts 64, 65 is exceeded or not attained and the relay 67 operated to control an ejector flap in the machine. Another circuit comprising a battery 69, a cross-coiled resistance measuring instrument 70 and a balancing resistance 71 is made through the plug and plunger. Associated with the pointer 72 of the instrument 70 is an adjustable micro contact 73 situated in the current source 74 followed by a delay-action relay 75. As the pointer 72 is deflected beyond the predetermined maximum value the contact 73 closes the circuit and operates the relay 75 which in turn ejects the faulty plug.