Patent GB-577598-A (GB)
Title: Improvements in apparatus for winding helixes
IPC: H01J19/00
Filed: 1944-01-17
Abstract: 577,598. Making electric discharge tubes. PORTER, C. B. A., and PRODUCTION PLANNING. & DESIGN, Ltd. Jan. 17, 1944, No. 901. [Classes 83 (ii) and 83 (iv)] Coiling ; caulking.-In an apparatus for winding a succession of spaced-apart wire helices on one or more longitudinal supports, which are severed to form electrode structures for electric discharge tubes, of the kind in which the supports are drawn by a gripper through the hollow spindle of a headstock while the wire is fed from a non-travelling guide into engagement with the supports and round a former fixed to the spindle, the spindle and gripper rotating in unison and the-speed of longitudinal movement of the gripper being cyclically varied to produce a succession of helices of close pitch separated by widelyspaced lengths, the gripper is moved longitudinally by a differential gear having two input elements connected to a common driving member, the connection between one of the elements and the driving member including speed-changing means, and means operatively connected to the driving member for cyclically changing the condition of the speed - changing means. The pitch of the helices and the length of the supports in the intervals between individual helices may thus be varied. The.support wires 17 are carried on spools mounted on a headstock spindle 14, Fig. 2, which is driven by a chain from a shaft 11 rotated by belt gear 12 from a motor 13. The spindle carries a grooved former 18 through which the wires 17 are drawn by grippers 20 on a slidable hollow shaft 19 which is keyed to a bush 22 rotated by a chain 24 at the speed of the spindle 14. The shaft 19 carries a split nut 25 which engages a lead screw 26 provided at one end with a flanged portion 27 keyed to a sleeve 29. The sleeve is driven from the shaft 11 by a chain 33 through a friction clutch loaded by a spring 34 which tends to rotate it in unison with the spindle 14, but is also connected to the shaft 11 through an exchangeable gear train 38, 39, 40 and freewheel clutch 41 so that the gear train causes the friction clutch to slip and limits the speed to any selected valve so as to give a slow feed to the shaft 19. The sleeve 29 may be stopped on application of a brake 31 so as to increase the rate of feed, the brake being operated by a solenoid 32 at the required time by a switch 55 through a cam 54 on a shaft 50 driven from the shaft 11 by a pawl 51 and ratchet-wheel 53. The wire 42 to be wound on the support wires 17 is fed from a spool over a non-travelling guide pulley into nicks cut in the wires 17 by a knife 44, the nicks being swaged over by a tool 45 to lock the helix wire therein. The knife 44 and tool 45 are mounted on levers 46, 47 operated by cams to move them towards and from the work. In order to wind helices of non- uniform pitch the lead-screw 26 may be reciprocated longitudinally with respect to the sleeve 29 by a lever 56 operated by a cam 57. The. lever 56 is pivoted on an eccentrically-mounted pin 58 rocked by a handle 59 to bring the cam into and out of operation. In another form, the gripper 20A, Fig. 3, is mounted in a carriage 62 and is rotated by gear 69, 68 from a splined shaft 63 which is driven through a chain wheel 70 by a chain 71 from the shaft 11A. The gear 69 is connected by a gear 77 to the split nut 78 which engages the screw 26A which is keyed to the sleeve 29A rotated by the chain 71 through sprocket 75 and friction clutch. The screw is also connected to the shaft 63 by exchangeable gear 80, 81, 82 and free-wheel clutch 41A to operate as in the first form. In this case, the cam-shaft 50A is driven by a ratchet-wheel 53A and a pair of pawls 51A from a shaft 61 carrying a sprocket 60 driven by a chain 15A which also drives the headstock spindle 14A. For winding helices of non-uniform pitch, the screw is traversed by an arm 84 having at its lower end a nut 85 engaged on a screw 86 on a spring- pressed shaft 87 which is displaced to the right by a lever 56A operated by a cam 57A. Fine adjustment may be effected by a tool applied - to the end 88 of the shaft 87. When winding to non-uniform pitch the swaging tool 45A is moved longitudinally relatively to the nicking tool 44A to keep the longitudinal interval between them equal to one half of the pitch of the last turn of the helix. For this purpose the lever 47A is fixed to a shaft 89 which is moved axially against the action of a spring 91 by a lever 93 operated by a cam 92. The lever 46A carrying the knife 44A is provided with two bearings 94, 95 and is slidably mounted on the shaft 89 by a spring 96 to engage a bell-crank 97 adjustable by a screw 98. The swaging tool may be mounted in a bracket 99, Fig. 6, having a shank 100 which may be secured in the detachable head 101 of the lever by a pinch screw 102, Fig. 7. The bracket may be adjusted transversely by a screw 103 with a micrometer head 1031 and may be angularly adjusted about the axis of the shank to suit different helix angles by a graduated plate 104 having a bearing on the shank 100 and slidably engaging a pin 105 rigid with the bracket and locked in various angular positions by a bolt 106. The lever 47A has an upwardly directed grooved pin 108 secured by a screw 110 in a socket in the head 101 which is held down by a screw 112 engaging an inclined notch 113 in the pin. The lever 46A has a similar lever head 114. The levers are connected together by a tension spring 190. The nicking or swaging tools may thus be renewed while a workpiece is still in position and partly wound. The spring 96 in this case is compressed between a nut on the shaft and a thrust bearing reacting through pins slidable through the bearing 90. The other end of the shaft 89 has an adjustable tappet engaging the lever 93. The lever 46A may be arranged to actuate a tappet 225 to close' a switch 55<1> instead of using the cam-operated switch 55A. The supports 17 may be deformed at 125, Fig. 1, to assist locating the electrode structure in mica spacers. For this purpose, the grooved former 18A, Fig. 10, which is secured in the end of the spindle. 14A by a collet chuck 126 operated by a nut 127, has wing-forming recesses 129 at intervals which co-operate with headed punches 130 mounted in radial bores in the spindle head and moved radially to deform the support wires during rotation of the head by a striker 141 which is pushed forward into the path of the punches against the action of a spring 146 by a bevel-ended rod 143 operated by a solenoid 147 controlled by a cam-operated switch through a rod 149 and tever 150. Outward movement of the punches is restricted by tongues on a washer fixed to the spindle nose. In order that when the length of the work is not an integral multiple of the pitch of the lead screw, the first helix of a series may have the proper spacing of the first few turns, means are provided for imparting longitudinal displacement to the gripper independently of the cam-shaft which changes the condition of the speed-changing means. The pivoted gripper jaws 153, Fig. 15, which are opened by a spring 155, are closed by a rod 156 through a spring 157. The rod 156 engages a cam 160 on a shaft 159 carrying a handle 164 and normally held by a spring with its lug 161 in contact with a stop 162 so that the jaws are closed. The split nut comprises half-nuts 25A, Fig. 16, radially moved outwards between a cover 168 and a flange 167 on the sleeve 76 by bevelled prongs 180 on, a striking ring 79. The half-nuts are pressed forward by springs 173 engaging strips of friction material 174 in grooves in the nut body, the strips being urged by the springs against the inside of a knurled ring 169 rotatable on the nut housing. The gear 77 is coupled by a key 175 to a ratchetwheel 176, the gears 77, 176 being rotatable on the sleeve. The wheel 176 is engaged by a spring-pressed pawl 177 carried by the nut body so as normally to transmit drive from the gear-wheel 77 to the nut, but acting also as a free-wheel. The ring 79 is actuated by a yoke 182, Fig. 14, on the shaft 159 having pins 183 engaging a groove 184 in the ring. When the ring 79 is free to slide to the right and the springs urge the half-nuts inwards, registration between the nut and screw is effected by rotating the knurled ring 169 in the normal direction of rotation of the nut, the free-wheel 176, 177 allowing the sleeve 76 and nut to be rotated as a result of the frictional drag imposed by the strips 174 until the half-nuts are fully engaged with the lead screw. In operation, while the machine is running normally, relay II, Fig. 18, is energized by circuit through contacts B, back contacts of relay I and coil II to energize motor contactor III. When the last helix of a series is wound, push-button P is pressed to de-energize coil II and stop the motor, the coil I being kept energized by a holding circuit through back contacts of relay II, contacts A and front contacts of relay I. The work is then separated from the headstock by a guillotine and the lever 164 urged clockwise to open the gripper so that the work may be removed. The lever 164 is then urged more strongly clockwise so as to force the ring 79 to open the half-nuts, pressure on the lever causing return of the carriage, the nose 187 of which comes against the bearing 64 and the handle is then released to close the jaws on the support wires 17. The carriage at the end of its backward stroke has depressed the switch plunger 188 to open contacts A, B and coil I is de-energized. On rotation of the sleeve 169 by hand, the half-nuts are first fully engaged with the lead screw as stated above and on continued rotation thereof the nut body and sleeve begin to move to the right to the extent permitted by slight end play between sleeve 76 and body 62. The contacts B are thus closed to energize coil II and start the machine again. The contacts A thus close to bring the electrical system into initial condition. The carriage may be arranged to operate a