Patent GB-792515-A (GB)
Title: Improvements in or relating to the manufacture of tubular fluorescent lamps
IPC: H01J9/24
Filed: 1955-09-02
Abstract: 792,515. Making tubular fluorescent lamps. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Sept. 2, 1955 [Sept. 7, 1954],No. 25232/55. Class 39(2) Tubular fluorescent lamps are bent into curved form by a machine comprising a rotatable turret carrying a plurality of heads in each of which a tubular lamp is secured while indexed through a succession of work stations at which it is preheated and exhausted, preheated and flushed with inert gas, and then heated and flushed a plurality of times, stretched to a predetermined length, bent into a circular shape, and finally fed with gas under pressure to remove any flattening of the envelope which occurs during the bending operation. In the example the straight tubular fluorescent lamps are already provided with a filament or cathode, mount, and have end caps or adapters sealed to the ends of the tube, at least one end having an exhausting-tube 28, Fig. 2, which has been preformed by offsetting into a position parallel with the tube axis. The turret machine 14 comprises a fixed vertical hollow shaft or centre post 54, Fig. 6, within which is rotatably mounted a shaft 60 carrying an upper turret 62, Fig. 5, connected by a sprocket chain to a gear-reduction drive with an output shaft 84 driving a one-revolution clutch on the main horizontal cam shaft 90, which carries an indexing barrel-cam 110 arranged to engage, in its rotation, a succession of conical rollers, e.g. twenty-four mounted adjacent to the periphery of a flat annular plate 130, Fig. 6, secured to, and coaxial with the shaft 60. The movable upper portion 66, Fig. 5, of a rotary valve is fixed to the shaft 60 just below the upper turret 62, the co-operating lower portion 70 of the valve being supported by a bracket secured to the stationary hollow centre post 54. Spaced around the periphery of the upper turret 62 are twelve lamp holders 30 which co-operate with similarly spaced holders 32 on the lower turret 64 to form twelve work-holding heads 16 into which a tubular lamp is loaded while the head is halted at station 12, there being twelve work-stations spaced around the periphery of the machine in correspondence with the heads 16. At station 1 the lamp enters a pre-heating oven 34, Fig. 1, and remains therein until its arrival at station 4, which is a pre-heating and gas-filling station, stations 2 and 3 being respectively the first and second preheating and exhausting stations. At station 5, the first heating and inert gas flushing station, the lamp enters and passes through the first heating oven 40 and is then indexed to similar ovens at stations 6 and 7. The lamp remains in the oven at station 7 a sufficient time to elongate to a predetermined length and then trips a control device for the indexing mechanism, thus ensuring a constant uniform length for all lamps prior to their entering station 8, where a bending-wheel 46, Fig. 1, forms the lamp tube 20 into a circular configuration. Prior to the removal of the bending wheel mechanism 46 the lamp tube 20 is engaged by a cradle 48, Fig. 19, which supports it while indexing to stations 9 and 10, the first and second cooling stations. The bent lamp is unloaded at station 11. Lamp holding heads. The holders 30 for the upper ends of the lamp tubes 20 are secured equidistantly around the periphery of the upper turret 62, Fig. 5, by inverted L-shaped brackets 140, each holder 30 providing support for a hollow vertical rod 142 the upper end of which is connected by a flexible tube 146 to the rotary upper portion 66 of the valve 66, 70. The lower end of the rod 142 carries a rubber tube 145 which receives the exhausting tube 28 of a lamp tube 20. The upper end cap 26 of the lamp is engaged within a bifurcated horizontal plate on a lamp support 150 carried by a plate depending from the bracket 140. The lower lamp holder 32 has a hollow supporting-rod 160 which is reciprocable within a bearing bush 162 in the lower turret 64 and aligned with the bifurcated plate of the support 150 of the upper holder 30. A collar 164, Fig. 6, and a contoured catch 166 are secured to the lower end of the rod 160 by a pin carrying a roller 167 and providing a pivot for a pair of links 169, Fig. 5 which are linked to a counterweighted lever 168 pivoted in an inverted U-shaped bracket 170 secured on the underside of the lower turret 64. In order to load a lamp tube 20 into a head at station 12 the operator raises the hollow rod 142 of the upper lamp holder 30 by operating the handle 144 with one hand and with the other, inserts the lower cap into the contoured upper end of the rod 160 of the lower holder 32. The end of the exhausting tube 28 at the upper end of the lamp tube is next fitted into the rubber tube 145. Lower turret braking. Three braking- devices for the purpose of preventing backlash are mounted equidistantly about the periphery of the stationary lower-table 56, e.g. at stations 4, 8 and 12. Each braking-device comprises an upstanding bracket 190, Fig. 27, provided with two lateral flanges 192 supporting slidable bolts 200 carrying a spring-biased brake shoe 198 positioned to engage the inner periphery of the lower turret 64. A transverse plate secured mid-way between the flanges 192 supports a vertical pin carrying a cam roller 202 which extends through a clearance slot in the brake shoe and rides on the inner face of the lower turret. Preheating oven. The preheating oven extending continuously throughout stations 1-4 has an open-ended tunnel-like form supported on a frame secured to the periphery of the stationary lower table 56, and carries a gas manifold 212 which feeds a gas mixture to opposed vertical rows of radiant burners at each of the stations 1-4. Heating-ovens. Each of the heating ovens 40 at stations 5-7 is mounted on a slide mechanism 218, Fig. 6, supported by a bracket 220 extending diagonally upward from the base plate 50. Each oven is in two halves slidable in opposite directions, the left-hand half 234, Figs. 4 and 6, being secured by a bracket 238 on a slide 224 and the right-hand half 236 by a similar bracket on a slide 226. The slides 224 and 226 consist of inverted U-sectioned channels with guide rollers 228 mounted within their curved portion to run on guide rails 222 under the control of mechanism 240 located at station 6 and operated by a barrel cam 122 on the main cam shaft 90, Fig. 1, of the machine. The cam 122, Fig. 5, engages a roller mounted on a vertical axis at one end of a lever 242 secured on the upper end of a shaft 244 journalled on the base plate 50, the other end of the lever 242 being connected by an adjustable link 248 to an arm fixed to a vertical shaft 252 upstanding from the ,base plate 50. The shaft 252 extends upwardly through the guide rails 222, Fig. 5, and carries a horizontal double-armed lever 254, connected by links 256 to the slides 224, 226. The halves of the ovens at stations 5 and 7 are opened at the correct intervals by associating them each with a vertical rocking-shaft 252 which is connected by a lateral link 262 to the shaft 252 at station 6. The lamp remains in the oven at station 7 for a time sufficient for it to elongate to a predetermined length, in which time the roller 167, Fig. 5, of the lower lamp head lowers into engagement with a stationary stop track 264 mounted on the outer periphery of the table 56 adjacent to stations 5-8, and thereby limits the stretching of the softened lamp tube. The engagement of the track 264 by the roller 167 initiates the indexing of the tube to station 8 by means of light-sensitive control device comprising a light source 272, Fig. 5, on the table 56, directed across the path of contact between the roller 167 and track 264 to a photocell 274 also on the table. A relay actuated by the photocell actuates a variable delay timer, and a solenoid 104, Fig. 1, is actuated whereby a dog on a dog lever 94 engages the gear 86, and the shafts 84 and 90 rotate as a unit. During the indexing of a lamp tube from station 7 to the bending-wheel at station 8 the lower lamp-supporting head 32 is moved downwardly, free from the lower-end of the lamp, by means of inclined guide tracks 280, 292, Fig. 11 (not shown) which engage the roller 167 on the lamphead 32 and guide it beneath a lip on a vertical rod which is reciprocated by connecting its lower end to a pull-down cam 120, Fig. 1, on the main cam shaft 90. At the bottom of the stroke of the lower lamp-supporting head 32 the contoured catch 166. on its lower-end is engaged and held between spring-biased detent plates 312, Fig. 13, (not shown). Bending-wheel mechanism. The bending- wheel mechanism 46 at station 8 is mounted on a bracket 322, Fig. 16, supported on a platform 184 and comprises a bending mechanism supporting-carriage 328 which is slidable upon a pair of vertical guide rods 324. A yoke 326 bridges the upper ends of the guide rods. Shown in plan in Fig. 15 the mechanism comprises a lefthand bending-wheel 340 on a shaft 342 carrying a gear wheel 344 connected by a gear train to a shaft 346 carrying a pinion 348, Fig. 16, engaging a rack bar 349 suspended vertically between the yoke 326 and the bracket 322. The right-hand bending-wheel 350 is mounted on a shaft 352 extending from the side arm of an angle bracket 330, and has a locking-pin 354 which engages within a complementary hole in the wheel 340 when the wheels are brought together face to face, so that they then rotate as a unit. Co-operating contact fingers 369 on each wheel close upon the lower cap 26 of the lamp tube 20 when the wheels are brought together. The unit is raised at predetermined intervals by a piston secured to the angle bracket 330, and operating within a vertical cylinder 370, Fig. 16, extending through the mounting-platform 184. The wheels 340, 350 are brought together by links 388, 388<SP>1</SP> pivoted to their outer bosses and operated by link couplings 390, 390<SP>