Patent GB-806507-A (GB)
Title: Improvements in exhaust machines for electric discharge devices
IPC: H01J9/38
Filed: 1956-10-18
Abstract: 806,507. Making electric discharge tubes. SYLVANIA ELECTRIC PRODUCTS Inc. Oct. 18, 1956 [Oct. 31, 1955], No. 31778/56. Class 39(2) [Also in Group XXX] Apparatus for exhausting electric discharge tubes having an opening at each end comprises a pair of carriers which support the tubes between them, at least one of the carriers being movable longitudinally with respect to the other along a supporting-base, each carrier being provided with a plurality of heads in axial alignment with heads on the other carrier, and means-on the heads for engaging hermetically the open ends of the tubes, means being also provided for effecting longitudinal movement of at least one carrier along the base while maintaining the heads in axial alignment. In the example the base comprises a pair of longitudinal supports or ways 38, 40, Fig. 2, for two carriers 32, 36 respectively, Fig. 1, the carrier 32 being fixed at one end of the base and carrier 36 movable longitudinally thereon by operation of a handle 78 on the end of a shaft 80 provided with a screwthreaded portion in engagement with a sleeve-nut on the underside of carrier 36. One fixed carrier 32 supports a rotary spider 10 mounted on a horizontal shaft 18 and provided with a plurality of workholding heads 12 of known type mounted at intervals around its periphery, there being similar heads 16 around the periphery of a spider 14 mounted on a horizontal shaft 24 on the movable carrier 36. Sprockets 54 and 60 secured on the inner ends of the respective shafts 18, 24 are driven by chains 52 and 58 which engage sprockets on a motor-driven shaft 48 within the base. Tubes 1 are loaded automatically between the carriers with their opposite ends within the aligned work-holding heads 12 and 16. Each head 12 is connected by a tube 106 to the rotary side of a valve 94 mounted on the shaft 18, with the co-operating stationary side of the valve connected by tubing 108 to a manifold 102 provided with a coupling 104 which connects to a vacuum source. In addition, each head 12 is associated with a "tipping" or sealing, torch 110 connected by a tube 112 to the rotary side of a valve 96 which has its stationary side connected by tubing 114 to a gas supply. The head 12 has a cam follower 116 on) its outer extremity which, during a part of the operating cycle, rids on a curved bar cam 118, Fig. 1, supported on arms 120 attached to an end pedestal 100, and the tipping torch 110 is mounted on a rod 122 the outer extremity of which is provided with a cam follower 124 riding on a curved bar cam 126 also mounted on the arms 120. The mechanisms actuated by the bar cams and their associated followers are described in Specification 805,896. During at least a portion of an operating cycle of the exhausting-machine the filaments are heated by current fed to the leading-in wires by flexible metal fingers 132, Fig. 1, which are attached to, but insulated from, the rod 122, each head of the machine being thus provided. The fingers 132 bear upon commutator tracks 130 mounted on and insulated from curved brackets 128 supported by the pedestals 30 and 34 of the respective parts of the machine. The heads 16 carried by the spider 14 are each provided, in addition, with a mercury dispenser 134 for introducing mercury into the lamp tube 1 instead of connecting the heads to a source of vacuum as in the case of the heads 12, and the ends of the tubes held by the heads 16 are connected in turn to supplies 136 of flushing-gas and filling-gas by way of a manifold 102a and a rotary valve similar to valve 94 at the other end of the machine. Automatic loading and unloading devices. Tubes are loaded into the machine from a conveyer 160 shown at the righthand side of Fig. 2, and unloaded finally on to a conveyer 162 at the opposite side, the requisite hermetic seal between the heads and the exhausting tubes at the two ends of the lamp tube bing effected automatically at the loading side by the displacement of a lever 140 on each of the successive heads by means of a roller on the end of a spring-loaded arm 144 in the path of the lever, as described in Specification 805,896.. Similar devices operate at the unloading side to release the grip on the exhaust tube after it has been sealed by the tipping torches 110, the removal of the sealed cullet being effected by connecting the heads through their respective valves 94 to a source of compressed air. Conveyer arrangement. The fixed carrier 32 and the movable carrier 36 are each provided with a loading-conveyer at one side and an unloading conveyer at the other side,. the respective conveyers co-operating to carry tubes between them in loading and unloading. The conveyers are driven from the main drive shaft 48 and, as shown in Fig. 2, the sprocket chain 58 driving the spider 14 engages also a sprocket 164 on a shaft 166 carrying sprockets 172, 174, Fig. 1, which, in turn, drive chains coupled respectively to the loader drive shaft and unloader drive shaft. Loading conveyer. Figs. 2 and 3 show the arrangement of the loading-conveyer 160 associated with the carrier 36 and comprising a vertically adjustable bracket 190 mounted on the pedestal 34 and carrying housings 192, 194 for shafts carrying guide or idler sprockets around which, extend endless conveyer chains 212, 214 respectively, these chains being parallel, but with one offset relative to the other. The chains 212, 214 carry between them the holders 210 upon which the lamp tubes are placed, each holder being connected by upper and lower pivots to the two chains. The loader driving-chain 176 is geared to drive a countershaft (not shown) which, in turn, is geared to a shaft 220 carrying the driving sprocket 222 for chain 212. A separate but synchronised chain and sprocket system drives the chain 214. Adjustment of the loading conveyers for tubes of various diameters is effected by vertical adjustment of the bracket 190 on the pedestal 34, an indexing block 241, Fig. 2, being arranged for predetermined settings for different diameters by means of screws of different lengths which project downwardly from the block and can be adjusted to abut on the base of the pedestal. Unloading conveyer The unloading conveyer 162 (shown at the left-hand side of Fig. 2), comprises supporting means for the shafts of two sets of sprocket wheels of which one set, consisting of wheels 276, 284, 298 is shown, the co-operating wheels 274, 282, 292, Fig. 4, of the other set being coaxial therewith. Each set of sprocket wheels is engaged by an endless chain, e.g. 280, Fig. 2, and the respective chains have a plurality of upstanding jaws 286, 288 which co-operate in pairs to receive between them the lamp tubes 1 as they are released from the machine. The sprocket wheels 274,276 and 282,284 are carried freely on two stub shafts, whilst the coaxial driving sprockets 292,298 are mounted on outer and inner concentric shafts provided with index discs 296, 302, Fig. 4, mounted face to face and adapted to be bolted together and to a third disc 304 in predetermined relative positions in order to alter the relative positions of chains 278 and 280 and thereby the spacing between the jaws 286 and 288 for tubes of different diameters. The disc 304 is keyed to a driving shaft 308 driven by chain 180. Oven-feeding devices. Before the tubes arrive at the loading-conveyer 160 they are fed through a heating-oven into which they may be inserted manually or mechanically. The oven frame, Fig. 5, comprises angle iron legs 314 and sides 316, the width of the frame being sufficient for the passage above it of a lamp tube of maximum length. Bearings 320, 326 on opposite sides of both ends of the frame support transverse shafts carrying sprockets associated with driving chains 334 which have their upper reaches riding on tracks 335 mounted on brackets 337. Each chain carries a plurality of upstanding fingers 336, and the idler shaft carrying the sprockets 330 at the right hand side of Fig. 5 has secured to it a series of discs 376 across the circumferences of which tubes such as 1a are placed in abutment with fingers 336a on the chains. The fingers advance the tubes into the oven while supported on the discs 376, whereupon the tubes leave the discs and roll forwardly down an inclined support formed by a series of parallel rods 378, thereby leaving the fingers 336a and rolling against the rear edges of the fingers 336b immediately in advance of 336a, thus assuming the position 1b Fig. 5. From there it advances to the position 1 at the left hand side of Fig. 5 and thence on to conveyer 160, Fig. 2.