Patent GB-789103-A (GB)
Title: Improvements in and relating to apparatus for making electronic tubes and the like
IPC: H01J9/38
Filed: 1955-10-05
Abstract: 789,103. Making electronic tubes and the like. GENERAL ELECTRIC CO. Oct. 5, 1955 [Oct. 5, 1954], No. 28408/55. Class 39(2) [Also in Group XXX] Apparatus for making electronic tubes comprises concentric inner and outer turrets each provided with a series of work holders which are indexed past successive work stations, and automatic transfer transfer mechanism whereby a tube consisting of a glass base or stem with glass envelope sealed thereto is removed from one turret while halted at a pretermined work station and moved to the other turret so that subsequent operations e.g. the evacuation of the tube by an exhausting pump can be effected, there being also electric contact members to supply heating-current through prongs projecting from the envelopes to the filaments thereof while on the outer turret. The inner turret 1, Figs. 1 and 2 which is disposed in a horizontal plane spaced above the outer turret 2 and on the same axis carries a plurality of tube sockets 3 spaced around adjacent to the periphery of its upper surface, each socket 3 being provided with a number of apertures or receptacles 4, Fig. 8 (not shown) arranged substantially around the circumference of a circle to receive the similarly arranged prongs or contact pins 5 of a tube stem 6. Each stem 6 comprises a glass button or base which supports on its upper side the tube elements such as filament or heater &c. connected to their appropriate pins or prongs 5 which extend through and are sealed within the glass button. These stem assemblies are mounted in the sockets 3 by an operator at a loading station, and at the same time a glass envelope or tube 7 provided with an upwardly extending exhausttube 9 is placed over the several elements with its lower edge in contact with the glass button. The abutting glass portions are fused together by heat applied at a subsequent station and the device is indexed to the transfer station, shown in Fig. 2, where it is transferred to an exhausting head 10 located on the outer turret 2, being inverted during the movement in order that the exhaust tube 9 may be inserted into the axial bore of a resilient member 14 and clamped in an air-tight connection. The transfer device which is supported on a stationary plate bracket 26 between the turrets 1 and 2 comprises a co-operating pair of jaws 73, Fig. 1, on levers 71, which are biased together by a spring 72 and are opened automatically by upward movement of a pair of spaced rollers 75 which are mounted an a vertically reciprocable member 76 and arranged to bear against angled cam surfaces on the ends of the levers 71 remote from the jaws 73. The member 76 is supported on the upper end of the plunger 78, Fig. 6 (not shown) of an air cylinder 79, so that a blast of air admitted to the cylinder operates to open the jaws 73 against the effect of the close ing-spring 72. The jaw-carrying arms 71 extend laterally from an extension 70 of a bracket 37, Fig. 3, which is bifurcated at its lower portion to form two limbs 30 each mounting a pair of horizontal studs 35 carrying rollers 34, the respective pairs of rollers being engaged within inverted U-shaped guide slots 33 in two spacedapart plates 32. The two limbs 30 of the bifurcated bracket form end bearings for a shaft 40 carrying a roller 41 which is engaged within an elongated slot 42 in an arm 43 secured on the shaft 44 of a pinion 50 engaging a horizontally reciprocating rack-bar 51 connected by a link and bellcrank system to a cam-operated rocking lever 63, Fig. 2. The arrangement and timing are such that, after the jaws 73 have been allowed to grip the exhausting tube 9 of an envelope, the rack-bar 51 is operated to rotate the pinion 50 clockwise, thereby swinging the arm 43 so that the rollers 34 on the bracket 37 are moved throughout the guide slots 33 of their respective.plates 32 and the bracket 37 assumes the inverted position shown in Fig. 5, whereby the end of the exhausting tube 9 is inserted into the axial bore of a resilient member 14 within the clamping- cap 15 of an exhausting-head 10 on the outer and lower turret 2. A collar 16 secured on the cap 15 carries a cam-arm 17 which may be operated either by a solenoid or an air-pressure device so that it loosens and opens the head during its approach to the transfer station and, after receiving an exhausting tube 9, engages a stationary part of the machine and is operated to compress the member 14 on leaving the transfer station. At subsequent work stations the envelope is evacuated, tested for leaks, and the tube 9 sealed off &c. Control of the plunger which is actuated to open the jaws 73 of the transfer device may be effected by a microswitch 85 or the like, Fig. 2, co-operating with an adjacent cam surface 87 to operate a solenoid or like means controlling the air flow into a cylinder. Energization of the filament during certain operations is effected when necessary by a pair of contact prongs 20 or the like, Fig. 10 (not shown) which are engaged by the requisite pair of pins 5 sealed into the glass head or stem 6 of the electronic tube, the pins 5 having been inserted into the precise sockets or apertures arranged therefor when loading the stem 6 in the head 3 of the inner turret 1.