Patent GB-421982-A (GB)
Title: Improvements in and relating to methods of and means for making grids for thermionicvalves and the like
IPC: H01J19/00
Filed: 1933-07-01
Abstract: 421,982. Making grids for thermionic valves. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.- (General Electric Co. ; Schenectady, New York, U.S.A.) July 1, 1933, No. 18739. [Classes 83 (ii) and 83 (iv)] Coiling; axial rolling; caulking; shearing- adjuncts.-In a machine for winding grids for thermionic valves &c., means is provided for forming coils of interrupted or varied pitch winding. A pair of support wires 10 are fed from reels 12, through a revolving head A by two pairs of reciprocating jaws B, B1. The wires are fed in grooves on opposite sides of a stationary mandrel A4. Notches are cut in the wires 10 by notching discs A67, Fig. 8, on the head A. When the head has revolved 180‹ the end of a grid wire is pushed into a notch by a nose A65 and a swaging disc A86 fixes the wire in the notch. The grid wire 11 is fed from a spool A32 on the head A. After a definite number of turns of grid wire have been wound a pair of knives A146 also mounted on head A are actuated to sever the grid wire. Since the support wires are fed continuously portions of the wires 10 remain free of grid wire until the nose A65 again operates. The mechanism for varying the pitch, Fig. 6, comprises a cam A160 which swings a yoke A69 on which the notching disc A67 is mounted while the feed of the support wires is varied. If the cam A160 is disconnected a uniform winding is formed. The support wires after winding pass to a pair of cutters C4, C5 which travel at the speed of the wires and severs them between the windings. Feeding support wires 10. The wire is fed by jaws B, B1. The jaws B1 grip the wires between the grid wire sections and feed them to the right, Fig. 2, whilst the jaws B move to the left to engage the wires when the jaws 131 are disengaged. The jaws are mounted on discs on a slide B8 and are opened and closed by a slide B18 operated by a cam B30 on a shaft A26. The slide B8 is actuated at the speed of the work by a cam B50 on the shaft A26 through a lever B38. To vary the feed the distance between pivots B36, B39, B40 of the lever B38 is varied by mounting the pivot B39 on a slide B41 adjusted by a screw B54. Feeding grid wire. The wire 11 is carried on the spool A32, Fig. 8, rotatably mounted on rollers A33 on the head A, and is fed over a pulley A35 and through a wiper A36 to a tube A38 pivoted on a slide A49. The pulley A35 is held by the tension of the wire 11 against the action of a torsion spring A39 attached by a brake cord passing over a pulley on the spool A32. If the grid wire breaks, the pulley A35 swings to cause a finger A48 to switch off the motor A18 and to tighten the brake cord A44 to stop the spool. Cutter mechanism for wires 10. The cutters C4, C5 are mounted on slides C6, C7 on a slide C3. The slide C6 is operated by a cam on the wheel C16. The slide C7 is actuated by a cam on wheel C29. A spacing-pressed guide is carried in the slide C6. As the slide C6 moves up, the guide enters between the wires 10 and raises them to the knife C4 to ensure a clean cut. The knife assembly is moved at the speed of the wires 10 by the slide C3 operated by a lever C37 and rod C44 from a cam C45. Notching wires 10. A sharp-edged disc A67 is mounted in a yoke A69 pivoted on a slide, adjustable by a screw A80, on the head A. As the head rotates the wire is placed in the slot by movement of a nose A65 actuated by a cam-lever A90. When a cam on the disc A116 lifts a lever A114, a slide A108 is raised to cause a cam A92 to move the nose A65 towards the fixed mandrel A4. Swaging. A swaging disc A86 is mounted on a slide A124 adjusted by a screw A126 on the head A. The cam A116 rotates once during the formation of the grid shown in Fig. 3 and raises means to retract the nose A65. The head A then makes three revolutions and the cam A116 then positions means which operate an arm A142 controlling the grid cut-off pivoted knives A146 actuated by links from a slide A149 actuated by the arm A142. After severance no wire 11 is fed until the cam moves the grid wire nose A65 into position when the winding is repeated. This provides for a space between the coils. To allow of coiling a grid of varying pitch as shown in Fig. 3, the cam A160, Fig. 6, is adjustable by a rod A164 and swings the notcher yoke A69 to position the notching tool a distance of half the pitch from the swaging disc. The rod A164 is actuated from the lever A167 by cam fingers A171, A172 which alternately position the lever A167 and cam A160 to high and low positions. A cam on the shaft A117 throws cam finger A171 over at the start of the coarse pitch windings to position the cam A160 and the notching tool A67. When the coarse winding is finished another cam throws cam finger A172 into position to restore the notching tool to normal position.