US3028712A

US3028712A - Apparatus for gas filling electric lamps

Info

Publication number: US3028712A
Application number: US817230A
Authority: US
Inventors: Jr John Flaws; Ray O Dunbar
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1959-06-01
Filing date: 1959-06-01
Publication date: 1962-04-10
Anticipated expiration: 1979-04-10

Description

APPARATUS FOR GAS FILLING ELECTRIC LAMPS Filed June 1, 1959 I I J;- "r 4.42

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nited States atenttlfice 3,028,712 APPARATUS FOR GAS FILLING ELEQTRIC LAMPS John Flaws, J12, East Cleveland, and Ray 0. Dunbar,

Willonghby, Ohio, assignors to General Electric Company, a corporation of New York Filed June 1, 1959, Ser. No. 817,236 2 Claims. (Cl. 53-88) Our invention relates to a method and apparatus for flushing and gas filling electric lamps.

The present invention is particularly concerned with gas filling electric incandescent lamps of the common so-called tipless type comprising a glass bulb having a re-entrant glass stem tube sealed to the end thereof and a glass exhaust tube within said stem tube and extending therefrom beyond the end of the bulb, and wherein portions of the said stem and exhaust tubes are fused and pinched together and an aperture or orifice is blown laterally from the exhaust tube through the fused mass of glass to afford communication with the interior of the bulb.

In accordance with present conventional practice, the lamps are assembled by sealing the mount structure, including the assembly of the stem and exhaust tubes and associated lead-in wires and filament, on a combination sealing and exhaust machine. After sealing, the lamps are transferred to exhaust ports on the machine where they are exhausted of air and flushed with nitrogen gas in a series of cycles which may occur eleven times, after which they are filled with a final atmosphere, usually consisting of a mixture of 88% argon and the balance nitrogen, followed by sealing off the exhaust tube. This operation involves a considerable investment in equipment since the machine includes a rotary valve, manifolds, glass traps, compression rubbers and chucks, and is provided with a source of vacuum that is external to the machine. In order to perform properly under vacuum, the rotary valve must be lubricated and when the oil used for lubrication is exposed to vacuum there is a likelihood that the flushing gas, when passing back and forth through the system, will pick up hydrocarbons evaporated from the oil and carry them to the rest of the vacuum system and into the lamps.

It is an object of our invention to avoid the disadvantages of the prior art process and equipment by dispensing with the exhaust operation and employing a flushing process wherein the air is displaced from the lamp by an inert gas and the lamp is then sealed to retain the gas as the permanent atmosphere. It is a further object to provide a method and apparatus which may be employed to flush and fill lamps of the tipless type with no alteration or modification in the construction of the lamp.

In accordance with one aspect of our invention, a fine hollow needle having a curved end is inserted into the exhaust tube of the lamp to cause the said curved end to project through and slightly beyond the aforesaid aperture in the stem. A flow of compressed inert gas is then supplied to the needle to be directed in a high velocity jet stream to the bulb wall at an acute angle thereto so as to provide a turbulent flow of the gas along the surface of the bulb wall and across the surfaces of the filament, lead wires and other internal elements whereby the resultant scrubbing action assists in dislodging and removing surface impurities on those parts. The gas is ultimately swept from the interior of the bulb through the said aperture and out through the exhaust tube around the said needle. The etfect of the scrubbing action of the gas flow is so beneficial and thorough as to produce lamps of a quality as good as or even surpassing that of lamps made on the conventional prior art equipment. Moreover, lamps of good quality may be made immediately at the start of the operation, whereas conventional apparatus must be run for a substantial period to clear away contaminations which have entered the exhaust system overnight, before lamps of good quality can be made therefrom.

Further features and advantages of our invention will.

appear from the following detailed description and from the drawing wherein:

FIG. 1 is a somewhat diagrammatic plan view of a form of flushing apparatus comprising our invention;

FIG. 2 is a vertical section, partly broken away, of the machine turret showing one of the heads and the gas distribution system;

FIG. 3 is a perspective view of the internal mount structure of a lamp in assembled relationship with a flushing needle; and

FIG. 4 is a perspective view of a sealing or tipping off mechanism in association with one of the machine heads.

Referring to FIGS. 2 and 3, the lamp which is to be flushed and gas filled is of the conventional tipless lYPe comprising a glass bulb 1 having a re-entrant glass stem tube 2 sealed to the end thereof and a glass exhaust tube 3 within the stem tube and extending therefrom. The stem and exhaust tubes are fused and pinched together to form a press or pinch portion 4, and an aperture 5 is blown laterally from the exhaust tube 3 through the fused mass of glass at the pinch seal 4 to afiord communication with the interior of the bulb 1. The mount structure also includes a pair of lead-in wire 6 which have portions thereof sealed in the pinch 4 and which carry a coiled tungsten filament 7. A glass arbor 8 also extends longitudinally from the pinch portion 4 and carries tie wires 9 for bracing the lead-in wires 6 and a-support wire 10 for additional support for the filament.

The apparatus illustrated herein comprises a turret 11 mounted on a vertical column or shaft 12 for rota-.

tion by a well-known indexing mechanism, and carries a plurality of heads or ports 13 at its periphery. Each of the vertically disposed ports 13 has a body portion 14 secured in a block 15 on turret 11 by its threaded lower end 16 and sealed by a seal ring 17. A hollow flushing needle 18 extends upwardly through the bore of the port body 14. Secured to the end of the needle 18 is an enlarged tubular base member 19 which has its lower portion cut away to a semi-cylindrical shape and which is supported in a well or passage 20 in the block 15 and is sealed off by a seal ring 21 which is compressed by the lower end of the port body 16. The needle 18, which,

when the exhaust tube 3 of the lamp is threaded down over the needle,'the said needle will frictionally engage the Walls of the tube in a manner tending to straighten out the needle at its bent portion 23, thereby causing the curved end 22 to snap out through the aperture 5 and project a short distance therefrom, for example about 1 mm. After the exhaust tube 3 has been inserted over the needle 18 and into the port body 14, it is preferably clamped tightly therein by rotating a threaded cap 24 to compress a rubber washer 25 around the exhaust tube.

The loading of the lamp into the head or port 13 is performed at station A (FIG. 1) and, as the head is indexed to station B, a flow of flushing gas, preferably nitrogen, is supplied to the needle 18. When the bulb is loaded, it is in aheated condition from the preceding operation of sealing the mount structure to the bulb. The gas issues from the curved end 22 of the needle in a Patented Apr. 10, 19ez stream directed upwardly at an acute angle to the vertical bulb axis and impinging against the wall of the bulb 1 to create a turbulent flow of the gas along the bulb wall, around the interior thereof, and past the internal elements in the bulb until it is expelled, along with the original atmospheric air, through the aperture 5 and through the exhaust tube 3 around the needle 18. The gas is vented from the lower end of the exhaust tube 3 by way of the bore of the port body 14, apertures 26 in the port body, a well 27 in block and passage 28 in block 15. a

The nitrogen gas is supplied to the well at the base of needle 18 through a passage 29 (FIG. 2) in block 15, passage 30 in the body portion 31 of a valve, axial passage 32 in valve stem 33, transverse opening 34 in stem 33, passage 35 in body 31 and conduit 36, when the spring-loaded valve stem 33 is depressed by a bell crank 37 which is connected to a push rod 38 which is pushed in upon engagement with the high surface 39 of a stationary cam track 40 surrounding the path of travel of the heads 13. The conduit 36 is supplied with nitrogen gas from a source of supply by Way of a conduit 41 and through a rotary connector or slip valve 42 at the axis of the turret 11 and which will be described hereinafter.

The flushing with nitrogen continues as the lamp travels around its path on the turret until it reaches station N (FIG. 1) when the valve controlling plunger 38 moves forward against a section 43 of the cam track 40 of reduced height whereby the valve stem 33 (FIG. 2) is raised by spring 44, the passage 35 is blocked, and a lateral aperture 45 in stem 33 is in communication with a passage 46 and conduit 47 which carries to the needle 18 a supply of filling gas which may consist of the conventional mixture of argon and nitrogen and which is supplied from a conduit 48 through the slip valve 42. The argon-nitrogen mixture continues to flow at a substantial pressure, to displace the nitrogen gas in the lamp bulb 1, until the lamp leaves station 0, at which time the argonnitrogen mixture flows at a reduced rate when the plunger 38 leaves the cam surface 43 so that the valve stem 33 is raised to its uppermost position to block both apertures 34 and 35 and permit the argon-nitrogen mixture to fiow from passage 46 through a constricted passage 49 under the lower end of valve stem 33 and into passage 30.

At station P the cap 24 on the port 14 is rotated in a direction to unscrew it and release the pressure on the washer 25, the lamp bulb is raised to a height such that the upper end of the needle 18 is located below the end of the bulb, and the exhaust tube is heated and tipped off at a position between the end of the bulb and the upper end of the needle. During this time, the low pressure flow of the argon-nitrogen gas is maintained to prevent ingress of air into the bulb.

The raising of the bulb and the tipping off operations may be performed by mechanism of a known type operating in synchronism with the indexing of the turret 11. As illustrated in FIG. 4, the mechanism comprises a supporting holder or cradle 50 which, along with a pair of gas burners 51, is carried at the end of an arm 52 which is mounted on a vertical rod 53. Upon arrival of a lamp at station P, the arm 52 is first swung to bring the cradle 50 under the lower end of the bulb 1 and is then raised to carry the bulb upward by suitable cam means (not shown) acting on the rod 53. The burners 51 heat a portion of the exhaust tube 3 to plasticity to close it off and sever it. The lamp 1 is removed from the cradle, and the residue of the exhaust tube is removed from the head 13 preparatory to loading another lamp into the head.

Referring to the rotary slip valve 42, it comprises a stationary cap portion 54 and a cylindrical body portion 55 which are screw-threaded together with a graphite seal ring 56 therebetween, and which are supported by bearings 57 on the upstanding cylindrical wall 58 of a valve ring member 59 on the turret 11. The argonnitrogen mixture flows from conduit 48 through a passage defined by the axial bore 60 of the cap 54, a metal sleeve 61, a graphite seal ring 62 and the interior of a tubular member 63 carried by the turret 11, from which it flows through a passage 64 to the conduit 47. The nitrogen gas fiows from conduit 41 through a lateral passage 65 in cap 54, through the annular space between sleeve 61 and the enlarged bore of cap 54, through a series of longitudinal openings 66 in a graphite sleeve 67 located between sleeve 61 and the enlarged bore of cap 54, and through the annular space 68 between wall 58 and tube 63 to a passage 69 connecting with conduit 36. The sealing rings 62 and 67 are pressed against the upper ends of the rotating tube 63 and wall 58 by respective springs 70 and 71.

In order to prevent a flow of gas in case a lamp bulb 1 should be absent from one of the ports 13, a valve stem 72 may be provided in the valve body 31 to block the passage 30. The stem 72 may be rotated by engagement with an arm portion 73 at its upper end, either manually or by a known form of solenoid-actuated mechanism including a feeler or sensing member which detects the absence of a bulb from the port 13.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus for gas filling an electric lamp bulb of the tipless type having a re-entrant glass stem tube and a glass exhaust tube within said stern tube and extending thereform and wherein portions of said stem and exhaust tubes are fused and pinched together and an aperture is blown laterally from the exhaust tube through the fused mass of glass atfording communication with the interior of the bulb, an elongated flexible hollow needle having a curved end and being of substantially smaller diameter than said exhaust tube for insertion into the exhaust tube with its curved end projecting through and slightly beyond said aperture, the mouth of said curved end of the needle being cut oft in a plane parallel to the axis of the adjacent straight length of the needle so that its overall transverse dimension is sufiiciently small to fit within the said exhaust tube, said needle being slightly bent intermediate its length in the same direction as its curved end so as to frictionally engage the walls of said exhaust tube at its bent portion and at its curved end in a manner tending to straighten out the needle at its bent portion during insertion into said exhaust tube whereby its said curved end snaps out through said aperture upon completion of the insertion, and means for supplying a flow of compressed inert gas to said needle for directing a jet of the gas against the bulb wall and flushing the air from the interior of the bulb and expelling it through the exhaust tube around the said needle.

2. In apparatus for gas .filling an electric lamp bulb of the tipless type having a re-entrant glass stem tube and a glass exhaust tube within said stem tube and extending therefrom and wherein portions of said stem and exhaust tubes are fused and pinched together and an aperture is blown laterally from the exhaust tube through the fused mass of glass affording communication with the interior of the bulb, a turret, a head mounted at the periphery of said turret and adapted to be carried thereby along a path of travel, said head comprising a port adapted to receive the end of the exhaust tube of an upright lamp and having therein passages venting the interior of the port and the exhaust tube therein, an elongated hollow needle extending upwardly through and beyond said port and having a curved upper end, said needle being of substantially smaller diameter than said exhaust tube and arranged to extend upwardly through an exhaust tube in said port with its curved end projecting through and slightly beyond the said aperture, the mouth of said curved end of the needle being cut off in a plane parallel to the axis of the adjacent straight length of the needle so that its overall transverse dimension is sufiiciently small to fit within the said exhaust tube means to supply a flow of compressed inert gas to the lower end of said needle during the travel of said head along its path to flush the air from the interior of the bulb and expel it through the exhaust tube around said needle, and tipping-off means adjacent the path of travel of said head including means operable to engage the bulb therein and raise it a distance suflicient to leave the upper end of said needle at a point intermediate the length of said exhaust tube and heater means arranged to fuse and seal off the exhaust tube at a point above the upper end of said needle.

References Cited in the file of this patent UNITED STATES PATENTS Payne Dec. 7, 1937 Smith July, 13, 19 43 Geiger Apr. 18, 1944 Geiger et a1. July 2, 1946 White Aug. 21, 1956 McCabe Feb. 24, 1959 Bowtell et a1. May 10, 1960