Patent GB-790234-A (GB)
Title: Glassworking system
IPC: H01J9/32
Filed: 1955-04-05
Abstract: 790,234. Sealing electric conductors into glass envelopes. CORNING GLASS WORKS. April 5, 1955 [April 9, 1954], No. 9970/55. Class 39(2) In a glass-working machine of the turret type, more particularly for sealing an electrically conducting element into - a hollow glass article such as a cathode ray tube held within a chuck and indexed step-by-step through a plurality of work stations, with means for heating a localized area of the glass article while indexed at certain stations, additional means are provided for heating the localized area of glass during the travel of the article between particular work stations, thus enabling the operating speed of the machine to be increased. In the example the invention is applied as a modification of the system described in Specification 698,052 for heating and perforating the glass wall of a cathode ray tube and closing the perforation by a metal element or button through which current is conveyed between opposite sides of the wall. Each tube-holding chuck is indexed successively through ten work stations (Fig. 1 not shown), a tube being loaded into a chuck at station 1. While travelling to stations 2, 3, and 4 the part of the inner wall surface at which the perforation is to be made is subjected to a highly localized intense heating flame, external heating of the same area also taking place while the article is halted at stations 2, 3, and 4. At station 5 a perforation is made in the heated and softened glass, and heat is again directed to the inner wall surface immediately bordering the perforation during travel to station 6. While the tube is halted at station 6 a button is deposited in the perforation either manually or automatically by means which may' be similar to that described in Specification 698,052, and during the travel from station 6 to station 8 heat is applied continuously to the button and the part of the inner surface of the tube bordering it in order to effect a hermetic seal or weld between them. Heat is directed against the outer surface of the button and the adjoining glass wall at stations 7 and 8. Sagging of the button and the glass immediately around it is overcome in known manner by seizing the glass and button and lifting them to the original positions while at station 9, and the' tube is removed from the chuck at station 10. The apparatus comprises a fixed base 11 supporting an axial column 12 with the turret 13 rotatably mounted on its lower portion and a fixed spider 25 mounted on its upper end and held against rotation by a key 27. The turret carries ten chucks 22 mounted at intervals adjacent to its circumference, and its underside is provided with a series of depending rollers 15 which are engaged successively in known manner by a wheel 16 on a shaft 17 which is rotated periodically by a single revolution clutch 19, Fig. 3, under the control of a pneumatic unit 23. The driving unit comprises a continuously rotating motor 30 connected through a gear-reduction unit 29 and transmission belt 24 to the clutch shaft. The ten work-holding chucks. 22 are each associated with a burner 48 for directing heat towards part of the inner wall of a tube 40, the burner being carried on a horizontal arm 47 attached to the upper end of a vertical push rod 45 movable within guides supported by a bracket 52 on the turret. Vertical movement of the burner 48 towards or away from the inner surface of the tube is effected by a stationary 'cam track 51 supported by brackets such as 50, 50<SP>1</SP> depending from the spider 25. and a co-operating cam-engaging roller 56 mounted on a stub shaft 55 secured to the lower part of the push rod 45 and extending laterally therefrom. The contour of the cam track 51 is such that it maintains a burner such as 48 or 48<SP>1</SP> in heating relation with respect to a tube while it is travelling from station 1 and also while travelling from station 2, 3 and 4, the burner being allowed to recede to a position of rest just prior to the arrival of the tube at station 5. After leaving station 5 the burner is raised to an intermediate position until it leaves station.6, whereupon it is raised to its uppermost position, where it remains until just before its arrival at station 9. It is then allowed to recede to its lowermost position. Burners for operating upon parts of the upper surface of a tube are each supported on a bracket 36 on the spider 25 at stations 2 to 5 and 7 to 9. As shown in Fig. 2 the bracket 36 at station 2 carries a pneumatic unit 37 comprising a piston rod 38 carrying a burner 75 supplied with a combustion mixture through a flexible tube 42 and arranged to direct a flame towards the exterior surface of a tube 40. The burner 75 is raised or lowered under the control of pressure fluid in the cylinder 37. Similar assemblies associated with vertically movable burners 73, 74, Fig. 3 are provided at stations 3 and 4. At stations 7 and 8, however, external heating burners 80, 81 are mounted at fixed heights and rotated about their axes by motors 76 and 77 respectively, Fig. 1, (not shown). Combustion fuel is supplied to the burners by the system indicated diagrammatically in Fig. 3, comprising gas and oxygen supply lines 68, 69 extending separately to distributing manifolds 34 and 33 respectively and each to a ported stationary manifold 35, the uppper burners being supplied from manifolds 34 and 33. Gas and oxygen are taken from the manifolds 33, 34 respectively by lines 57, 58 to mixing chambers 59 associated with the burners. Fuel is supplied to the burners 48, associated with the chucks 22 through the stationary manifold 35 and a co-operating rotary manifold 41, lines 43, and 44, mixing- chamber 49 and fuel line 46. Perforating equipment. The perforating equipment at position 5 comprises a pneumatically operated punch 70 and a co-operating die 60, the latter being carried on the free end of the piston rod 61 of a pneumatic unit 62 which is suspended from the piston rod 65 of a pneumatic unit 66. Unit 62 operates to advance the die 60 into vertical alignment with the punch 70, but stops the die short of the height necessary to bring it into engagement with the tube. Unit 66 operates to raise unit 62 vertically to bring die 60 into engagement with the inside wall of the tube. Since the piston rod 61 of pneumatic unit 62 when in its forward position is in the path of travel of tubes arranged in the chucks 22, movement of the turret 13 is prevented unless the piston rod 61 is retracted. To ensure this the fluid supply line 178 to the pneumatic unit 23, which controls the single revolution clutch 19, includes a valve 175 having an operating stem 176 normally held in the closed position by a spring 177, the said valve being open to permit the supply of actuating fluid fed through a valve V only when the piston 61 of unit 62 is retracted, as described in Specification 698,052.