Patent GB-746668-A (GB)
Title: Improvements in and relating to bulb washing and reflector coating apparatus
IPC: H01J9/20
Filed: 1953-03-12
Abstract: 746,668. Making electric lamps. BRITISH THOMSON-HOUSTON CO., Ltd. March 12, 1953 [March 14, 1952], No. 6824/53. Class 39(2). Apparatus for cleaning the interior surface of an electric lamp bulb and applying a reflecting metal coating thereto by thermal vaporization of a metal, comprises a horizontally disposed carrier provided with a series of bulb-holding heads which support the bulbs in an upright position with their open neck downward while they are indexed through a series of work stations at one of which a stream of cleaning fluid is injected, subsequent stations having means for expelling the remaining cleaning liquid, thoroughly drying the interior of the bulb, and heating the interior to a temperature of the order of several hundred degrees Centigrade but below the softening point of the glass, after which the bulbs are transferred successively and automatically to a second horizontally disposed carrier, adjacent to the first and substantially in the same plane, with a series of heads which receive the bulbs and index them through successive work-stations for the coating process, means being provided for indexing .the carriers in synchronism and in timed relationship with bulb-loading and transfer devices which operate when the carriers are stationary. In the example the bulb washing apparatus comprises a rotary turret A, Fig. 1, provided with sixteen work-holding heads 4 and located adjacent to the coating apparatus comprising a turret B with sixteen work-holding heads 5, the turrets being indexed in a counterclockwise direction, e.g. by drum-type cams mounted beneath them on horizontal shafts and arranged to engage between a series of rollers on vertical axes disposed in a circle on the undersides of the turrets. Each head 4 of turret A comprises a bulb-holder or chuck 26, Fig. 5, mounted for rotation about its vertical axis and having a collar 27 provided with upstanding spring fingers 28 over which the bulb 6 is pressed so that the fingers engage within its neck 7. An endless belt 30 extending around adjacent to the periphery of the underside of the turret is arranged to rotate the bulb-holders 26 when opposite any work-station except the first, or loading, station A1 and the sixth and seventh A6, A7 respectively, where the belt is carried around an idler pulley instead of around the pulley associated with the bulb holder. The bulbs may be loaded manually into the machine or, as shown in Fig. 1, by an automatic transfer and loading device T which picks up the bulbs in succession from a supply line 34 comprising a track 35 along which they are pushed. After being loaded at station A1 a bulb is advanced to station A2 where a jet of cleaning solution such as chemically pure (deionized) water at a temperature of approximately 135F. is sprayed into it from a nozzle 36, Fig. 3, and at the next three stations A3-A5 the water is drained from the bulb with the assistance of compressed air through nozzles 37-39. These water and air nozzles 36-39 are arranged to be raised and lowered in unison through the bulb holders 26 and in and out of the bulbs during their dwell at the respective work stations. The nozzles are mounted in two pairs in two separate blocks 41, 42 which are carried at the upper ends of rods 43, 44 supported in guide brackets 47, 48 and each formed with a rack portion to engage an adjacent pinion 50, 51 secured on a shaft carrying a sprocket 55, 56. The sprockets are engaged by an endless chain 54 driven by a sprocket 57 secured on the shaft of a rocking arm 63 carrying an end roller 62 within a surface slot 61 in a rotary cam 60, whereby the sprocket 57 is oscillated and transmits vertical reciprocation to the blocks carrying the nozzles. The nozzles are maintained in a set axial position by providing the blocks 41, 42 with inwardly directed guiding arms 64, 65 respectively each carrying a guide roller which engages within a vertical slot 67 or 68 formed between pairs of guide plates 69, 69 and 70, 70 mounted on transverse plates 71. Rigid pipes 73-76 connect the respective nozzles to passages in the supporting blocks 41, 42, and from the latter a flexible supply pipe 77 connects to the water supply, and pipes 78-80 to compressed air. The compressed air supply may be maintained continuously, but the supply of de-ionized water may be interrupted during the indexing of the turret, by a solenoid-operated valve 81, Fig. 5, controlled by a pair of series connected switches 84, 85. Switch 84 is operated by a timing-cam 86 on a main cam shaft 10, and switch 85 is closed by a bulb 6 engaging a control arm 85<SP>1</SP> when it enters the washing station A2. From station A5 the bulb 6 is carried through two idle stations A6, A7 to allow any remaining water to drain therefrom, and at stations A8 and A9 is heated externally by radiant gas burners 87 to vaporize any moisture remaining. On passing successively through stations A10- A13 the vaporized moisture within a bulb is forced out by low pressure jets of heated air directed therein from nozzles 88, Fig. 4 (not shown), while the external heating by gas flames is continued. The hot air nozzles are mounted in supporting blocks for vertical movement similar to that of the water and compressed air nozzles 36-39, with the inclusion, in the hot air supply, of a vertically arranged rubber bellows coupling to a manifold which receives hot air from an oven. During further successive indexing through the final stations A14-A16 the bulb is heated intensively in an oven 100, Fig. 1, to about 300C. to prepare it for subsequent evacuation and internal coating operations on the turret B. The oven 100 extends over the part of the turret from between stations A13 and A14 to between stations A16 and A1, and may be heated by burners 103 or other means. After leaving station A16 the bulb is indexed to the unloading and loading station Al where the transfer device T is operative. The transfer device T, Figs. 1 and 6, comprises a spider member with a pair of arms 106, 107 secured tcgether at 90 degrees to each other and rotatable about a common vertical shaft 111, each arm carrying a bulb pick-up suction cup 109 or 110 at its outer end. The spacing between the suction cups is such that when cup 110 is aligned with a head 5 at station B2 of turret B the cup 109 will be aligned with the head 4 at station A1 of turret A ; this spacing is also equal to that between a head 4 at station A1 and the foremost bulb 6 in the supply line of bulbs on the track 35. The cups 109, 110 are also arranged for vertical reciprocation at intervals by vertical movement of the shaft 111 which is rotatably and vertically movable within vertically spaced bearings 112, 113, Fig. 10, on the ends of arms 114, 115 carried by a stationary bracket 116, the bracket serving also as a mounting for a compressed air cylinder with an elongated piston rod 119 connected by tie arms 120, 121 at its upper and lower ends to the corresponding ends of shaft 111. A solenoidcontrolled valve 124 connected by conduits 122, 123 to the upper and lower ends respectively of cylinder 118 is controlled by a switch 125 actuated by a timing cam 126 on the shaft 10. The suction cups 109, 110 each comprise a shallow inverted cup member 166, Fig. 9, with an internal seating ring made of indiarubber to fit closely upon the top 6<SP>1</SP> of a bulb, and the upper surface of the cup has a hollow boss 168 which seats within a recess at the lower end of a tube 171 carried within a boss 172 at the end of the carrier arm 106 (or 107), the tube 171 being slidable relative to the arm 106 under the control of a spring 178 tensioned between a stud in the boss 172 and a stud in a collar 177 secured on the tube 171. A flexible tube 181 connecting the cup to the vacuum source, permits a limited upward movement of the cup when it is moved down upon a bulb. Three or more resilient wire fingers 179 extending down from the tube 171 act to centre the bulb relative to the cup. Oscillation of the arms 106, 107 between bulb pick-up and delivery position is effected by a swivel bracket 127, Fig. 10, which is swivelled about the shaft 111 under the action of a crank-operated arm 134 while allowing relative vertical movement of the shaft, the outer ends of the arms 106, 107 being connected by a link 132, Fig. 6, carrying a guide 131 for a vertical bar 130 which is mounted at the end of an arm 129 extending upwardly from the bracket 127. A connecting-rod 136 connects the arm 134 to a crank 137, Fig. 6, controlled by a motor-driven gear system which has a clutch controlled by a solenoid in a cam-operated circuit that is momentarily energised twice during each period of dwell of the turrets A and B. The flexible tubes 181, 182 connected to the suction cups 109, 110 are connected through solenoid-controlled valves 183, 184, Fig. 10, to a common vacuum source and the solenoids are connected in a circuit with a switch 185 controlled by a timing cam 186 on the cam shaft 10. The heads 5 on turret B, Fig. 12, each comprise an upright holder 187 over which the bulb neck fits, and a compression rubber chuck consisting of a rubber ring 188 located between upper and lower clamping rings or washers 189, 190 so that it can be expanded against the inside wall of the bulb neck to form a vacuumtight seal. This is effected by raising the clamping-ring 190 by means of a pair of cam rings 191, 192 located beneath it, the abutting faces of the cam rings being such that when the upper one 191 is rotated by means of a lever 195 it is lifted axially. The lever 195 is operated to compress the sealing ring at station B3 and relieve it at station B15. The upper clamping ring 189 and lower cam ring 192 are both fixed upon a central tube 196 which provides an exhaust passage. The bulbs are inserted on the heads 5 when they arrive at station B2, but before this a vaporizing element 199 is inserted into the upper end of the bulb holder 187 by an operator a