US3341272A - Process of manufacture of incandescent lamp - Google Patents

Description

N. P. DEMAS PROCESS OF MANUFACTURE OF INCANDESCENT LAMP Filed Sept. 1B, 1964 ATTORN EYS United States Patent O 3,341,272 PROCESS F MANUFACTURE 0F INCANDESCENT LAMP Nickolas P. Demas, Cranford, NJ., assignor to Wagner Electric Corporation, a corporation of Delaware Filed Sept. 18, 1964, Ser. No. 397,401 6 Claims. (Cl. 316-17) The present invention relates to the manufacture of incandescent lamps and comprises a novel process which as compared to processes heretofore in use, is substantially simpler and results in lamps having pure gas fills and of consistently higher quality.

The process of the invention omits all stages of lamp manufacture in which the lamp bulb is exhausted. This reduction in the number of operating stages substantially lowers manufacturing costs and eliminates danger of oil vapor contamination resulting from use of vacuum pumps and oil sealed rotary valves. In the new process no exhaust tube is required and therefore butt seals are not required and sealing alloys other than dumet can be employed for the leading in wires. The new process therefore saves not only equipment but also labor and moreover results in a superior product. Briefly, the invention comprises the use of a flush tube for driving out air from the envelope which is to form the lamp bulb and for replacing the driven out air with a flush gas. The flush tube is introduced into an open end of the envelope and then withdrawn during the fusing and pinching of the open end to form the final seal. The rate of introduction of flush gas into the envelope is so controlled as to avoid turbulence. A uniform fill of gas and tight hermetic seal of the lamp is obtained.

For a better understanding of the invention and of the advantages thereof reference may be had to the accompanying drawing of which- FIGS. 1 through 6 represent sucecssive stages of the process of the invention as applied to the manufacture of a cartridge type lamp; and

FIGS. 7 and 8 represent the process as applied to a single ended type of lamp.

In the drawing, the various means for supporting the parts have been omitted as it will be understood that conventional rotary type lamp making machinery having means at each stationary for supporting the lamp par will be employed.

In FIG. 1 there is illustrated diagrammatically a tubular glass container 2 having reduced neck or end portions 4. This represents the first stage wherein the container or envelope 2 is loaded on to the machine.

In FIG. 2 the envelope 2 is shown with a filament 6 disposed axially therein and with lead-in wires 8 and 10 connected to the filament 6 and extending through the neck portions 4. At this stage in the process the mount comprising the lfilament and lead wires is suitably supported so as to -be disposed within the envelope 2. In the next step of the-process the lower neck 4 is heated and pressed together to fuse the glass about the lead 10 and seal the lower end of the envelope. The process so far described is conventional in the ordinary and presently used process of lamp manufacture. Following the stage represented by FIG. 3 in conventional practice, an exhaust tube would be butt sealed to the upper neck 4 and the envelope 2 would be repeatedly exhausted and flushed prior to the nal filling with fill gas and tipping off of the exhaust tube. In accordance with the present invention these various steps are omitted and instead, as shown in FIG. 4, a iiush tube 12 of relatively small diameter, for example, of .050 with a bore of .030", is inserted through the upper open neck 4 of the envelope 2 to a depth adjacent the lower end of the filament 6. An inert -gas of approxi- 3,341,272 Patented Sept. 12, 1967 ICC mately 88% argon is introduced into the tube 12 from a suitable source of supply at a relatively slow rate, for example, at a rate of one cubic foot per hour. During the introduction of the inert gas the upper neck is heated to soften the glass and at the end of approximately 30 seconds the flush tube 12 is raised and withdrawn from the envelope 2 while the fused upper neck 4 is pinched to seal the envelope and secure the lead 3 therein. The supply of a flush gas is turned oft just prior to removal of the flush tube 12 from the envelope 2. FIG. 5 illustrates this final step of removal of the flush tube and pinching of the fused neck 4 and FIG. 6 illustrates the completed cartridge type lamp.

FIGS. 7 and 8 represent the process of the invention as employed in the manufacture of small gas filled single ended lamps such as indicator or read-out lamps. In these figures the flush tube 12 is shown as extending through the open neck 1-6 of a bulb 20 to a point adjacent the lower closed end of the bulb. As shown best in FIG. i8 which is a view taken at right angles to that of FIG. 7, the tube 12 clears the filament 22 and glass buttons 24 fused about the lead-in wires 26 of the lamp. As described in connection with the cartridge type lamp, inert gas is introduced through the tube 12 into the bulb to displace the air therein and fill the bulb with the inert gas. The neck 16- of the bulb is heated and, while withdrawing the tube, the fused neck is pinched to seal the bulb and secure the lead-in wires in the press.

From the foregoing description taken together with the drawing, it will be apparent that the present process eliminates many -conventional steps in the manufacture of gas filled lamps and that the elimination of such steps provides the following advantages over conventional manufacturing processes:

(l) Elimination of vacuum pumps.

(2) Elimination of rotary oil sealed valves as used on present production exhaust machines.

(3) Elimination of oil vapor contamination of internal lamp parts due to oil vapors from vacuum pumps and oil sealed rotary valves.

(4) Elimination of Vacuum type connections such as are used on present exhaust equipment.

(5) Elimination of exhaust tube.

(6) Elimination of exhaust tube tipping operation.

(7) Eliminationof butt seals and consequently the opportunity for use of sealing alloys other than dumet wire.

Prior to the present invention it had been assu-med that a pure gas fill in a lamp could only be effected after the lamp had been completely evacuated of all air and moisture and for this reason processes heretofore in use have included at least two stages of evacuation. In accordance with the present invention it has been found that provided the rate of introduction of the fill gas is not too rapid, the air and moisture can be completely driven out of the envelope by the introduction of the fill gas and that this can be effected in a relatively short period of time. In FIGS. 4 and 7 the dashed lines issuing from the lower end of the flush tube 12 represent the direction of flow of, first, the air in the tube and then of the fill gas which replaces the air during the process.

It will be apparent from the foregoing description that the new process of manufacturing gas lled lamps is not only cheaper and simpler to practice but results in a superior product.

The following is claimed:

1. A process of manufacturing an incandescent lamp which comprises the steps of flowing a stream of fill gas into the open neck of a heat fusible envelope containing a filament, said open neck constituting the sole opening in said envelope, delivering said flowing gas stream to an end of said envelope remote from said open neck, reversing the direction of ow of said gas stream at said remote end back towards said open neck and spreading said gas stream laterally at a rate of flow sucient to completely displace air from said envelope but insufficient to cause turbulence, fusing said open neck when said envelope has been filled with said ll gas, and uniting the walls of said fused open neck about at least one lead-in wire for said filament, said method being carried out without refrigerating said fill gas in order to condense it into liquid form.

2. A process as in claim 1 wherein the point of delivery of ll gas is gradually withdrawn from the envelope.

3. A process in claim 1 wherein the fill gas is substantially pure argon.

4. A process as in claim 1 wherein the fill gas is delivered at the rate of approximately one cubic foot per hour.

5. A process as in claim 1 wherein the ll gas is delivered for about thirty seconds at the rate of approximately one cubic foot per hour.

6. A process as in claim Z wherein the flow of said gas stream is stopped just prior to withdrawal of the point of delivery thereof from said envelope.

References Cited UNITED STATES PATENTS 3,162,499 1'2/ 1964 Gustin S16-24 RICHARD H. EANES, JR., Primary Examiner.

Claims (1)

1. A PROCESS OF MANUFACTURING AN INCANDESCENT LAMP WHICH COMPRISES THE STEPS OF FLOWING A STREAM OF FILL GAS INTO THE OPEN NECK OF A HEAT FUSIBLE ENVELOPE CONTAINING A FILAMENT, SAID OPEN NECK CONSTITUTING THE SOLE OPENING IN SAID ENVELOPE, DELIVERING SAID FLOWING GAS STREAM TO AN END OF SAID ENVELOPE REMOTE FROM SAID OPEN NECK, REVERSING THE DIRECTION OF FLOW OF SAID GAS STREAM AT SAID REMOTE END BACK TOWARDS SAID OPEN NECK AND SPREADING SAID GAS STREAM LATERALLY AT A RATE OF FLOW SUFFICIENT TO COMPLETELY DISPLACE AIR FROM SAID ENVELOPE BUT INSUFFICIENT TO CAUSE TUBULENCE, FUSING SAID OPEN NECK WHEN SAID ENVELOPE HAS BEEN FILLED WITH SAID FILL GAS, AND UNITING THE WALLS OF SAID FUSED OPEN NECK ABOUT AT LEAST ONE LEAD-IN WIRE FOR SAID FILAMENT, SAID METHOD BEING CARRIED OUT WITHOUT REFRIGERATING SAID FILL GAS IN ORDER TO CONDENSE ITO INTO LIQUID FORM.

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