Patent GB-698052-A (GB)
Title: Methods of and machine for sealing electrically conductive elements into glass envelopes
IPC: H01J9/32
Filed: 1950-11-23
Abstract: 698,052. Sealing electric conductors into glass envelopes. CORNING GLASS WORKS. Nov. 23, 1950 [Jan. 25, 1950; March 9, 1950], No. 28691/50. Class 39(ii) A machine for sealing an electrically conductive element within a perforation in the wall of a glass article, e.g. sealing a terminal button in a cathode ray tube, comprises automatically operating means for depositing the conductive element within the perforation, and means for heating the element and the surrounding glass to effect a weld or sealed joint therebetween. In the example, a number of cathode ray tubes are located in a series of holders spaced around the periphery of an intermittently rotating table, and are indexed successively through ten work stations or positions. At position 1 a tube is placed in a holding-chuck, and at positions 2 and 3 intense, highly-localized, heating flames are directed upon opposite wall surfaces in the area at which a perforation is required. At position 4 the softened glass is perforated by a conventional punch and die, and at position 5 further heating of the perforated glass takes place. Still further heating takes place at position 6 and a button is deposited automatically in the perforation, and carried to positions 7 and 8 where further heating effects a hermetic union between the glass and the button. At position 9 the button and the glass immediately surrounding it are lifted slightly to remove any sagging that may have occurred, after which the tube proceeds for removal at position 10. A table 13, Fig. 3, provided with ten circular chucks 22 for tubes 40 is mounted on a hub 14 which is rotated intermittently about an axial column 12 by an indexing wheel 16 engaging a succession of rollers 15 mounted on vertical axes on the underside of the table, the shaft 17 of the wheel 16 being driven periodically through a singlerevolution clutch 19 controlled by an associated pneumatic unit 23, Fig. 2, (not shown). A stationary turret 25 secured on the upper end of the column 12 is provided around its periphery with the operating devices enumerated for the positions 2 to 9 at which the rotary turret 13 is halted. Fig. 3 shows co-operating upper and lower burners 39, 48 mounted at position 8, at which stage a button 41 is already located within the perforated wall of a tube 40. The burners are mounted at the ends of pistons which are movable within differential pneumatic units 37,46 respectively, the units being connected normally to compressed air supplies and operating to hold the pistons in retracted positions until a chuck 22 is indexed between them, whereupon. burner 39 is lowered and burner 48 advances through the chuck 22 into close proximity to the inner wall of the tube 40. Fig. 3 also shows the perforating equipment at position 4, comprising an upper punch 60 carried by a pneumatic unit 61, and a co-operating die 50 mounted on the piston rod 51 of a pneumatic unit 52 operating similarly to unit 46 and adapted to advance the die into vertical alignment with the punch 60, the final . perforating movement . being effected by bodily vertical movement of the unit 52, which is suspended from the piston rod 55 of a pneumatic unit 56. The heating of the glass around the perforation, at positions 5 and 6, and the welding heat at positions 7 and 8, is effected by burners similar to those shown in Fig. 3. Fig. 5 shows the button-inserting equipment at position 6, comprising a small rotary turret 71 carried at the bottom of a shaft 73 which is rotatably mounted within a hub 74 formed integrally with a pneumatic unit 80 supported by a bracket 75 extending from the stationary turret 25., The upper end of shaft 73 is provided with a sprocket wheel 76 driven by a chain 116 and a sprocket 115 on a vertical shaft which is geared to rotate intermittently with the table 13, and between the sprocket 76 and hub 74 there is located a compressed spring 77 which normally holds the turret 71 in engagement with the bottom of hub 74. The turret 71 is provided with three chucks 72 spaced at 120 degrees and adapted to be connected to a vacuum source so that a metal button inserted therein, either manually or by a conventional feeding device, is held in position until the vacuum is cut off. The vacuum source is connected to a, lateral pipe 82 which connects with an annular chamber around part of the shaft 73, and the shaft is provided with an axial bore and radial passages leading to . an annular chamber 88. The chamber 88 connects to three radial passages extending therefrom to the respective chucks 72, each passage being controlled by a valve on a headed sterri 96 adapted in its outer position, as shown in Fig. 5, to connect the button 41 to the vacuum. The control action is such that, when the button 41 is above and aligned with, the perforation. in the tube, the piston 81 of the pneumatic unit 80 is operated to press the turret 71 down to place the button just above the perforation, and at the same time compressed air is fed to an adjacent pneumatic unit 105 causing an abutment member 106 on the piston of the latter to push the valve stem 96 inwardly, whereupon the vacuum is cut off and the button drops into the perforation. The inner end of . the valve stem 96 also abuts against a loose annular collar 107 within the chamber 88, and in its inward movement shifts the collar laterally so that the other two valve stems within turret 71 are moved outwardly to connect the associated chucks 72 to the vacuum source.