Patent GB-805882-A (GB)
Title: Method of and apparatus for making supports for wire coils
IPC: H01K3/10
Filed: 1955-09-16
Abstract: 805,882. Making coiled filament and heater supports. GENERAL ELECTRIC CO. Sept. 16, 1955 [Sept. 17, 1954], No. 26609/55. Classes 83 (2) and 83 (4). Shearing; stamping; solenoid - actuated hammers.-A method of providing a wire coil 12, Fig. 10a, particularly a coiled filament for an incandescent lamp of the kind described in Specification 805,881, [Group XI], or an infra-red ray heater, with one or more supporting discs 63, comprises feeding to the coil a metal strip 2, Fig. 2, having spaced longitudinal slits 78, whereby the leading slit passes over the coil wire between adjacent turns, Fig. 7a, and punching from said strip a disc 63 engaged with the coil. A coil of the strip 2, which may be of tungsten, tantalum or molybdenum is inserted in a drum 80 and the strip fed into a gap 5 between a die block 7 and punch block 6. The feed mechanism comprises a pair of guide pads 84, 85, Fig. 4, preferably of nylon, disposed on opposite sides of the strip and pressed against it by a " U " spring 86. The latter is secured to the armature 89 of an electromagnetic vibrator 88 which armature passes through a slot 90 in a fixed stop member 91. On each stroke of the armature the latter strikes against the bottom 92 of the slot causing the strip to be fed downwardly by its own inertia. A length of filament coil 12, Fig. 7, is fed from the left into the bore of the die and punch block and is supported in a slot 57 of an anvil 53 slidable in the bore of the die block and carried on an arm 54, Fig. 2, secured to a shaft 55. The left hand end of the coil is located by a member 74 secured to the shaft 55 and the strip 2 is fed downwardly by the vibrating feed, assisted manually if necessary whereby the leading slit 78 which has a flared opening 79 passes over the coil wire. A punch 10, Fig. 7, is then pressed to the left by a handle 15, Fig. 2, secured to a collar 16 fast with the punch to clamp the strip against the anvil 53. A mandrel 37 of heat-treated spring-temper steel, having a pointed end 39 of pyramidal or conical form, is then forced through the strip by movement of a hand lever 41 connected by link 43 to a slide 35 carrying an electromagnetic vibrator 46 with a chuck 48 receiving the mandrel. A supporting sleeve 48<SP>1</SP> prevents buckling of the mandrel. As the slide 35 is moved to effect the piercing, a switch 50, Fig. 1 (not shown), is closed to energize the vibrator whose action assists the piercing and subsequent withdrawal of the mandrel. The piercing produces tabs 38, Fig. 10a, around the pierced hole which curl outwardly and wrap around a filament coil. Thereafter further movement of the slide 35 closes a switch 31, Fig. 2, to energize a solenoid 20 whose armature is connected to a striker arm 22 engaging a tubular hammer 26 slidably mounted on the punch 10, whereby the hammer strikes the collar 16 and forces the punch to sever a disc 63 from the strip, Fig. 10 (not shown). The anvil is thus displaced against a biasing spring 59, Fig. 2, out of the die block where it falls away from the die axis and is held by a pawl 64 biased downwardly by a torsion spring and having lugs 72, 73 engaging above and below the anvil arm 54. The pawl is subsequently raised by a handle 71 to raise the anvil and cause it to re-enter the die block by the pressure of spring 59. The disc 63 is then located between jaws 75 of the member 74 for positioning the coil ready for the next disc 63 to be secured thereto.