Patent GB-805896-A (GB)
Title: Apparatus for exhausting electric discharge devices
Inventor: DODGE ERLE HENRY
IPC: H01J9/38
Filed: 1955-12-01
Abstract: 805,896. Making electric discharge devices. SYLVANIA ELECTRIC PRODUCTS, Inc. Dec. 1, 1955, No. 34481/55. Class 39(2) [Also in Group XVIII] Apparatus for exhausting an electric discharge device, such as a fluorescent lamp, having two exhausting tubes extending therefrom comprises a carrier or conveyer provided with heads which engage the exhausting tubes hermetically, and valve means for connecting the heads on the conveyer to relatively fixed conduits during operation of the apparatus, e.g. one head being connected to a source of flushing gas while another head is connected to a vacuum pump. In the example the machine comprises two spiders 10 and 12, Fig. 1, keyed to a horizontal shaft 14 supported in bearings 16 on a base 20. The spider 10 is provided with a series of heads 22 spaced equally around its periphery, and spider 12 is provided similarly with an equal number of heads 24. A pair of valves 26, 28 each comprising a fixed and a rotary disc are located adjacent to the spider 10 and concentric with the shaft 14 to provide communication with the heads 22, and valves 30, 32 of a similar type adjacent to the spider 12 provide communication with the heads 24. Continuous rotation of the spiders and the lamp tubes carried longitudinally between their peripheries is effected by a gear wheel 62 keyed on the intermediate portion of the shaft 14 and driven through mitre gears on shafts coupled to a gear reduction device 42 driven by a motor 34. A lamp 1 is fed, automatically or manually, in a horizontal position, into a cradle formed by a pair of standards 64, Fig. 2, mounted on the base 20 and is taken up therefrom automatically by a pair of co-operating heads 22, 24 when these become adjacent to the respective ends of the lamp tube, a succession of tubes 1 being thus picked up at the left-hand side of the machine and unloaded subsequently at the righthand side. The lamps are conveyed through an oven defined by inner and outer walls 68 and 70 respectviely, Figs. 1 and 2, the inner wall 68 being formed by a plurality of fire bricks 72 connected to one another by tie rods 74 and supported by transverse angle irons 76 mounted on arms 80 supported by tables 18. The outer wall comprises rows of burners 82 separated by insulating material 84, the burners being mounted on channel-iron members 86 which, at each end of the oven, support gas and air manifolds 92, 94 respectively. Each set of gas and air manifolds feeds a plurality of burners in each row. At each end of the machine a frame 96, Fig. 1, mounted on the base 20 has a stationary valve-plate-support 98 bolted thereto. At the left-hand end a pin 104 extending into the plate 102 of the valve 30 holds the plate against rotation and in gas-tight abutment with the movable plate 106 which is fixedly mounted on the hub of the spider 12. The valve 32 at the same end of the machine comprises a stationary plate 110 held in frictional engagement with the movable plate 112 mounted on the shaft 14. Similarly at the other end of the machine a pin 126 extends into and holds the plate 124 of the valve 26 stationary, there being a gas-tight seal between that plate and the movable plate 128 mounted on the hub of the spider 10. The adjacent valve 28 comprises a fixed plate 132 held in frictional engagement with a movable plate 134 fixedly mounted on shaft 14. The valve plates comprising the respective pairs, viz 102 and 106 of valve 30, and 124 and 128 of valve 26, are held concentric by self-aligning ball bearings at their respective ends of the shaft 14. The movable plates 106 and 112 of the two valves 30 and 32 are connected to each head 24 by a plurality of flexible tubes 146 and 148. Similarly each head 22 is connected to the movable plates of valves 26 and 28 by a plurality of flexible tubes 150, 152. Gas and oxygen supply valves 156 and 160 at the opposite ends of the machine are connected by tubing 154 and 158 to their respective stationary plates 110 of valve 32 and 132 of valve 28. Also a plurality of tubes 162 and 164 from the respective stationary plates 102 and 124 of valves 30 and 26 are connected to various feeding lines for different operations at certain periods during the exhausting cycle. In the example the valves 26, 28 and 30, 32 accommodate or serve twenty-four pairs of heads 22, 24 mounted around the peripheries of the spiders 10 and 12 respectively, the heads all being provided with similar burners and tube-holding devices. Each head 22 is, however, provided with its own mercury dispenser and associated mercury reservoir 234, Fig. 6. Each head 22 comprises a base 182, Fig. 4, bolted on the peripheral flange of spider 10 and supporting a spring-biased rod 186 with a burner-supporting plate 188 mounted on the inner end a cam-follower block 190 secured on the outer end. The cam follower roller 194 rides upon the edge of an adjacent cam 180, Fig. 1, during the travel of its associated head 22 around the machine, thereby causing the rod 186 and burner 244 carried by it to be moved first towards and then away from the end of a lamp tube secured in that head, in effecting the sealing-off of the exhaust tubulation 7. The base 182 also supports bearings for a longitudinally slidable sleeve 206 positioned above and parallel with the rod 186 and coaxial with the burner 244, the outer end of the sleeve having secured therein an arm 208 carrying a cam follower roller 210 which travels along the edge of a cam 178, Fig. 1, thereby moving the sleeve 206 axially outward against the action of a spring 212 abuting a stop collar 214 secured on the sleeve. The part 220 of the arm 208 within sleeve 206 provides a bearing for one end of a horizontal rod 224 having a limited axial movement relative to the sleeve against the pressure of a pair of springs 230, 232 separated by a central stop 228 secured to the rod. The inner end of the rod 224 carries the mercury reservoir 234 Fig. 6, containing a mercury dispenser whereby 7 measured amount of mercury is admitted into the discharge tube, and the cover plate 316 of the reservoir is provided with a hollow seating 364 for a resilient collar 362 which can be compressed upon the exhaust tubulation 7 of a lamp tube 1, this device and a similar device co-operating with it on a head 24 at the other end of the lamp tube being the sole means for holding and supporting the lamp tube on the machine. The exhaust tubulation 7 enters the head 22 through a funnel guide 368, Fig. 6 with an inner flange 366 which can be pressed inwardly on to the resilient collar by screwing a cap 372 inwardly by actuation of a lever 374 clamped on the cap. A toothed sector 376 coaxial with lever 374 is in mesh with a gear sector 378 on a lever 380 mounted on a pivot 382 on the cover plate 316 of the mercury reservoir, whereby operation of lever 380 serves to unscrew cap 372. The resilient collars within the respective heads are uncompressed when the heads 22, 24 arrive at the loading station, and the heads are in their retracted position, and ready to receive a lamp tube 1 between them. The lamp tube 1 is taken from the loading cradle 64 by cradles 266 at the ends of arms 268 projecting from the burner plates 188, whereupon the further rotary movement of the machine causes the heads to move inwardly under the action of their control cams to encompass the exhausting tube 7. After a short travel of the tube on the conveyer the clamping lever 380 on the head 22 strikes a roller 390, Fig. 2, on a spring-biased lever 386 and is swung to clamp the exhaust tube 7 in an airtight connection. A similar arrangement acts on head 24 at the opposite end of the lamp tube. While in the oven the lamp is flushed with inert gas such as argon and evacuated, and the electrodes are heated to break down the electron-emissive coating thereon. The inert gas is fed from a source not shown through one of the tubes 164 at the right-hand side of Fig. 1, to the stationary plate 124 of the valve 26, and passes intermittently to the tubing 150 extending out of the movable plate 128 of the valve, the passage being through ports 125, Fig. 17 (not shown), in the stationary plate and ports 129, Fig. 16 (not shown), in the movable plate as the latter move into and out of register with the ports in the fixed plate. From the tube 150 the inert gas passes through bore 151, Fig. 6, in the mercury dispenser 234, and through sleeve valve 342, bore 357 of an ejector pin and tubulation 7 of the discharge tube. At the left-hand side of the machine one of the tubes 162, Fig. 1, extending from the stationary plate 102 of valve 30 is connected to a vacuum pump (not shown), and the movable plate is connected by tubing 146 to the lamp tube 1 through bore 304, Fig. 9 (not shown), and through ports of an ejector pin 296 to the tubulation 7. Pumping through the valve 30 is continuous because of the relative location of the rings of elongated slots in stationary plate 102 and rings of ports in the movable plate 106, Figs. 18 and 19 (not shown). Current is fed to the cathodes 9 of the lamp through tracks 172, Fig. 1, which are engaged by flexible metal fingers 174, 175 mounted on the heads 22, 24. Mercury dispenser. After the initial flushing and evacuation of the lamp a measured quantity of mercury is introduced through the head 22 by way of the mercury dispenser, Fig. 6 and 8, comprising a mercury bucket 324 which is rotatable upon a fixed sleeve 322 secured in a boss 320 on the cover plate 316 of a mercury reservoir 234. A scoop 326 on the bucket leads to a chamber 328 which, in its vertical position, shown in Fig. 8, registers with a port 330 in sleeve 322. The extent of rotation of the bucket on the sleeve 322 is limited by a screw 338 on the bucket journal extending into a slot 340 in the sleeve 322, and terminating in a shoulder 344 which engages within an aperture in the rotary sleeve valve 342, so that when the bucket moves to the position shown i