Patent GB-484430-A (GB)
Title: Improvements in and relating to the manufacture of electric incandescent lamps
IPC: H01K3/10
Filed: 1937-02-18
Abstract: 484,430. Making electric incandescent lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 18, 1937, No. 4926. Convention date, Feb. 18, 1936. [Class 39 (ii)] In making a filament mount comprising current leads l, Fig. 1, with hooked ends projecting from and beyond a stem press 22, an intermediate filament-support w, and anchor wire supports a for the leads between their hooked ends j and the stem press, the coiled filament f is first brought into a bowed form in the machine and held thus with its coiled ends projecting, the ends are then placed within the hooked ends j of the leading-in wires and clamped therein, and the intermediate supporting wire w is curled around the mid-portion of the filament and bent into position approaching the axis of the mount, after which the leads l are brought to definite positions approaching an axial plane of the mount and the anchor wires a are bent into corresponding positions across the leads and their ends curled around the latter, the mid-portion of the filament being finally pressed temporarily out of contact with the intermediate support so as to equalize the tension in the filament at opposite sides of the intermediate support w. Fig. 3 shows the spider as first presented to the machine to receive a filament, which is preferably of the coiled-coil type and, as supplied to the machine, has loosely coiled ends and mid-portion. The operations may be carried out in a machine similar to that described in Specification 390,807, the spider being manufactured at the stations preceding station 11, Fig 4, at which station a filament is transferred to it from a positioning and shaping mechanism A by a transfer device T. The shaping-mechanism A may be similar to that described in the prior Specification, comprising a base plate or slide 30, Fig 6, which is recessed to provide longitudinal guideways 31 for a slide 32 which is itself provided with guideways 35 for a sub-slide 36 which is urged forwardly by a compression spring 38. The forward edges of slides 32, 36 are curved in a concave arc corresponding to the curvature of a die 42 upstanding above the base plate 30, the front edge of slide 36 being also notched vertically to co-operate with a vertical stud 44. The front portions of the slides 32, 36 are overhung to engage a filament f which is deposited in the position shown in Fig. 6, so that when slide 32 is moved forwardly the slide 36 advances with it and pushes the filament forward until its mid-portion m engages stud 44. Further movement rolls the portion m partly around the stud until slide 36 strikes the die 42, whereupon slide 32 continues to move and bends the filament around the corners of die 42, with its ends sticking out. The projecting ends are next positioned or centred by a pair of gripping-devices each comprising two coacting finger-levers 60, 61, Fig. 10, pivoted on a common stud 62 and urged apart by a compression spring 64, a vertically movable cam-plate 65 being mounted below their lower ends to control the opening and closing action. The lever 60 carries a block 70 with a V-notched end which is slotted vertically to receive an upstanding wire 71 on the end of lever 61, so that the filament end e can be located within the V-notch in the block 70 before being positioned definitely in the plane at right-angles to that in which levers 60, 61 move. The positioning means for this comprise a funnel-like socket device 75, Figs. 10, on an arm 76 carried by a bracket 77 which can be rocked by a crank arm 85 and link 86. The socket device 75 comprises a stud 81 screwed adjustably into arm 76 and formed with an enlarged head with a conical end recess, so that when bracket 77 is rocked back the filament ends e are caught and pushed back to the necessary position. The transfer device T now swings through 180 from its position in Fig. 4 over towards the filament ends and grips them, whereupon the holding means 70, 71, Fig 10., are released and the transfer device, now carrying the filament, swings back to its former position and places the filament ends e e within the open hooks h of the leading-in wires of the stem waiting at station 11, where they are clamped tightly by the mechanism B. The mechanism B comprises a pair of coacting clamping-jaws 90, 91, Fig. 12, for the hook h of each leading-in wire, these jaws being mounted in a slide head 92, with the jaws 90 fixed in position while the jaws 91 are pivoted thereon and connected by links 95 to a block at the upper end of a vertically movable rod 96. An upstanding finger 102 between the pairs of jaws is adapted to engage the filament anchor wire w. The slide-head 92 is in a lower position than that shown in Fig. 12 when the spider is first brought above it, and is raised by upward movement of rod 96 until the hooks h, h are engaged in grooves 100 in the jaws 90, whereupon further upward movement of the rod 96 forces jaws 91 outwardly upon the hooks to clamp the filament ends therein. A spring- pressed plunger 103 is provided in one jaw 90 to prevent unsymmetrical bowing out of the filament toward this side. The wire w is next bent downwardly and its end curled around the mid-portion of the filament, after which the uncompleted mount is transferred from station 11, through station 12 to station 13 where the supporting-wire w is bent further, almost into a vertical position by a pair of oppositely directed blade-like members. At position 14 it is acted upon by mechanism D, Fig. 4, to position the leads l, l and curl the ends of the anchor wires a, a loosely around them. This mechanism comprises a pair of adjacent pusher plates 132, Fig. 19, formed each with a V-shaped notch to receive a leading-in wire l, and a co-operating pusher plate 133 mounted on an arm 135 which is swung inwardly to overlap the plates 132 and hold the leading-in wires l within notches in the latter. The anchor wires a, a are then pushed against the wires l by a sliding pusher bar 140 mounted in the bracket 126, Fig. 19, and controlled by a cam acting against the tension of a spring, after which the ends of the anchor wires a are curled around the leads l by dies 145, 145 mounted on the ends of dovetail slides 146 which are guided in ways arranged on bracket 120 in the direction of travel of the mount. The stem is next indexed to position 17 where a pair of resilient wire fingers bear upon the filament on either side of the supporting wire w and temporarily press its mid portion out of contact with the surrounding curl of the wire w, so that its mid-portion can shift longitudinally to equalize the tension in it on opposite sides of the wire w. A similar pair of resilient fingers bear upon the filament leads l and bend them back until they lie in the axial plane of the mount. The completed mounts are now released from the mounting-machine and caught within a holder 174 on a conveyer F at station 18.