US3320012A - Method of manufacturing photoflash lamps - Google Patents

Description

May 16, 1967 Fig}.

R. M. ANDERSON Fig 2.

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METHOD OF MANUFACTURING PHOTOFLASH LAMPS Filed June 29, 1965 2 Sheets-Sheet 2 ';;f 29 1 30 l 7 E l i L l 35 6 3/ 3/ 5 t 1 l, J/+4 lnven tor: Robertr,M.Ar?e son His AU COTTWeH United States Patent O 3,320,012 METHOD OF MANUFACTURDIG PHOTOFLASH LAlVIPS Robert M. Anderson, Euclid, Ohio, assignor to General Electric Company, a corporation of New York Filed June 29, 1965, Ser. No. 467,886 Claims. (Cl. SIG-) This invention relates to a method or process for producing tubular photofiash lamps. More particularly, it relates to a method for the production of such lamps which are sealed on one end by an exhaust tip.

It is a constant goal in the photoflash lamp industry to produce ever smaller lamps which will give greater and improved light output. Such improved flash lamps are described and claimed in applicants copending application Serial No. 467,831, filed concurrently with the present application and assigned to the same assignee. Such lamps provide increased internal volume relative to overall external dimensions. This is accomplished by changing the geometry of the tipped end of a standard commercial AG-l photoflash lamp by eliminating the gradual curvature of the dome from the lamp bulb to the tip and substituting therefor relatively straight cylindrical walls that extend out a substantial distance along the length of the tip and then are sharply turned back into the bulb in a re-entrant direction to form a retroverted well surrounded by a rim. The tip arises from the approximate center of the well. However, a process was required for the high-speed production of photoflash lamps having such a configuration.

Accordingly, it is a principal object of the present invention to provide a process useful for the production of photoflash lamps having a re-entrant dome with a somewhat recessed tip.

Another object is to provide such a process which is capable of economical and highly reproducible utilization on high-speed commercial flash lamp production equipment.

Other objects and advantages of the invention will be apparent from the description and the accompanying drawings.

In the drawings:

FIG. 1 is a side elevational view of a flash lamp tube having a base formed thereon with ignition means and electric contact means in place and with filamentary combustible material in position for further processing of the lamp tube blank.

FIG. 2 is a side elevational partly in section of the flash lamp tube of FIG. 1 being drawn down to form an attenuation or contraction.

FIG. 3 is a side elevational view of the step in the process of the invention in which the dome is heated and blown out into its desirable convex shape.

FIG. 4 is a side elevational view of the step in the process of the present invention in which the attenuation is pushed into the dome of the lamp to form the unique end structure of flash lamps claimed in applicants abovementioned application Ser. No. 467,831.

FIG. 5 is a side elevational view, partly in section, of the step in which the flash lamp bulb is cooled in a bath of liquid nitrogen while it is exhausted and filled with a combustion-supporting gas.

FIG. 6 is a side elevational view partly in section of the step in which the exhaust tip is formed and sealed off by the melting of the glass.

FIG. 7 is a schematic view of a flash lamp prepared according to the present invention.

Briefly stated, the present invention in one aspect provides a process for producing tubular photoflash lamps ice having one end closed by an exhaust tip comprising the steps of:

(A) Heating the lamp tube at the conjuncture of the lamp bulb with the attenuation, (during this step, a gas can be blown into the lamp bulb to round out the top of the lamp bulb, forming a dome),

(B) Allowin the attenuation to cool sufiiciently for it to become rigid enough so that it can maintain its shape while forcing the still hot and plastic inner portions of the conjuncture or dome down into the lamp bulb, and

(C) Causing the attenuation and the lamp bulb to move relatively toward each other to depress the central portions of the conjuncture or dome, forming a re-entrant raised rim surrounding a retroverted well at the end of the lamp bulb.

Subsequent sealing of the lamp by tipping can be done, for example, with a cooled bulb or in a pressurized chamber to make lamps having a fill-pressure above atmospheric. Other methods can be used when the fill-pressure is below atmospheric.

In one aspect, the present invention lies in certain manufacturing steps added to a process for producing photoflash lamps described and claimed in Patent 3,188,162 Anderson et al., which is assigned to the assignee of the present invention.

Many details and several steps of the process for producing photoflash lamps according to the present invention are identical to those for producing prior art AG-l photofiash lamps as described in above-mentioned Patent 3,188,162Anders0n et al. The steps related to the changes in the process for the production of improved photofiash lamps as described in above-mentioned Patcopending patent application Ser. No. 467,831 Will be particularly described herein. Reference may be made to Patent 3,188,162 for equivalent processes useful in pro ducing standard AG-l lamps.

Referring now to the drawings, FIG. 1 shows a glass lamp tube 1 which has already had a stem-press base 2 formed at one end and filamentary combustible material 7 inserted and compressed in the vicinity of the stem press sealed end. A lamp mount comprising lead wires 4 is sealed through the stem press 2. The external ends of the lead wires form electrical contacts 3, and the lead wires inside the lamp can be held in fixed relative position by a glass head 5. The innermost ends of the lead wires are covered with primer ignition material 6, which also is in contact with the flashing filament 35 as shown in the front view of a lamp in FIG. 7. The lamp tube is held by an upper holder 8.

As is known in the prior art, lamp tubes can be processed to this stage by sealing lead-in wires into one end of a glass lamp tube to form a stem-press base on the lamp tube, with the mount structure having ignition means including a filament wire at its end inside the lamp, and allowing for electrical contact means with its ends outside the lamp. Primer material can then be applied through the open other end of the lamp tube on to a portion of the leaddn wires located within the lamp tube so that the primer material contacts the filament Wire. Combustible material may then be introduced through the open end of the lamp tube by any of the several suitable means disclosed by the prior art and positioned adjacent to the ignition means in the vicinity of the sealed end of the lamp. This prevents the combustible material from being deleteriously acted upon by the process of forming and sealing the other end of the lamp.

FIG. 2 illustrates attenuation 9 separating lamp bulb 19 from the balance of the lamp tube 13. For this operation, the lower end of the lamp tube 1 which is to form the lamp bulb It may be held by mechanical means or by vacuum means in a lower holder 16. A screen 17 controls the position of the lamp in holder 16, while vacuum means may be applied below the screen 17 such as through tube 16a. This holder 16 is mounted on a supporting shaft 18 which terminates in a hemispherical bearing 19. The bearing 19 follows cam track 20 at the upper and lower holders 8 and 16, with the lam tube being formed, are indexed from one position to another around a lamp-making machine. Upper and lower holders 8 and 16 are rigidly connected together so that the lamp tube 1 can be moved as a unit as the glass is worked.

During the attenuating of the lamp tube, fires a are played on the tube while it rotates, as shown by one arrow. These fires 15a coming from burners 14a causes the tube wall to collapse inwardly somewhat, with the curvature shown at 12a. After the glass has moved inwardly sufficiently, the lower holder 16 is caused to move downwardly by the configuration of track as. the lamp is moved around a lampmaking machine. In this lower position, burners 14!; continue to play fires 15b on the tube to form the desired attenuation, which still must stay open to allow subsequent exhaust and filling of the lamp. This step results in the lamp bulb having a gradual curved end 12 from the cylindrical portions of the bulb wall to the conjuncture 11 of the bulb with the contraction 9.

At the next step, as shown in FIG. 3, the lamp is indexed into a position where burners 23 direct relatively smaller fires 24 on the conjuncture 11 of the bulb 10 at its end 12 with the contraction 9. The lamp is rotated during this process as shown by the arrow, and a gas is blown into the upper end of the lamp tube 13 such as through a hose 21 and connecting plate 22 to cause the end 12 to expand outwardly into a convexly curved dome. This results in heating the lamp tube at the conjuncture of the lamp bulb with the attenuation, or contraction, 9, as it is referred to. The attenuation 9 is then allowed to cool sufficiently to become rigid enough so that it can maintain its shape While later forcing the still hot and plastic inner portions of the contraction 9 down into the lamp bulb. Following this step, the lower holder 16 with the lamp bulb 10 is caused to move upwardly in relation to the upper part of the lamp tube 13 by a rise in the cam track 20 at 25. FIG. 4 illustrates the continuation of the rise 25 in cam track 20 at 26. When the cam bearing 19 has risen to the upper level of the track at 26, the lamp bulb 10 will have been pushed upwardly along the common axis of the bulb 10 and the tube 13 relative to the then cooler attenuation 9 as illustrated. Of course, any means by which relative motion of the lamp tube 13 and the lamp bulb 10 toward each other could be accomplished would have an equivalent effect. This causes the attenuation 9 to push the center ortion of the dome downwardly to form a retroverted well 27 surrounded by a re-entrant rim 28.

In the next step, the upper end of the lamp tube 13 is gripped in an exhaust-fill apparatus 29 (FIG. 5) which comprises a rubber valve 30 actuated by jaws 31. The lamp is exhausted by vacuum means through the exhaustfill head 29 and then filled under a moderate absolute pressure with oxygen gas. The lamp bulb 10 is then immersed in liquid nitrogen in a trough 36, in order to give a resulting pressure in the finished lamp of about 7.5-8 or more atmospheres.

In the tipping operation shown in FIG. 6, sharp flames 33 from burners 32 are used to locally melt the attenuation 9 in order to form tip 34. This tip 34 will normally extend slightly above the rim 28, although its height from the bottom of well 27 is comparable to that of standard AG-l photofiash lamps. During this tipping operation, the lamp 10 may, if desirable, be removed from the liquid nitrogen bath and held in a holder such as that shown at 37 and in transfer mechanism 38 adapted to remove the semifinished lamp bulb 10 from the lamp-making machine on which these steps have been performed.

FIG. 7 is a schematic representation of a semifinished lamp ready for the application of protective plastic coatings to the outside of the bulb. After a holding period to identify leaking lamps, plastic coatings may be applied to the lamps for safety purposes. The electrical contacts 3 may be bent into any desired shape during, before or after the lamp processing sequence provided only that the retroverted ends 39 have previously been sealed into the lamp base if such a construction is desired.

While specific examples have been given of the process of the present invention, it Will be understood that various changes, omissions and substitutions may be made within the spirit and scope of the invention as defined in the appended claims.

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

1. In a process of producing tubular photofiash lamps having one end closed by an exhaust tip wherein the tip is formed by heating a portion of the lamp tube and drawing it out to form an attenuation through which a combustion-supporting gas is later introduced into the lamp and the exhaust tip then closed by heating, the steps of:

(A) heating the lamp tube at the conjuncture of the lamp bulb with the attenuation,

(B) allowing the attenuation to cool sutficiently for it to become rigid enough so that it can maintain its shape while forcing the still hot and plastic inner portions of the contraction down into the lamp bulb, and

(C) causing the attenuation and the lamp bulb to move along their common axis relatively toward each other to depress the central portions of the contraction and form a reentrant raised rim surrounding a retroverted well at the end of the lamp bulb.

2. In a process of producing tubular photoflash lamps having one end closed by an exhaust tip wherein the tip is formed by heating a portion of the lamp tube and drawing it out to form an attenuation through which a combustion-supporting gas is later introduced into the lamp and the exhaust tip then closed by heating, the steps of:

(A) heating the lamp tube at the conjuncture of the lamp bulb with the attenuation while blowing a gas into the lamp bulb to round out the top of the lamp bulb and form a dome,

(B) allowing the attenuation to cool sufiiciently for it to become rigid enough so that it can maintain its shape while forcing the still hot and plastic inner portions of the dome down into the lamp bulb, and

(C) causing the attenuation and the lamp bulb to move along their common axis relatively toward each other to depress the central ortions of the dome and form a reentrant rim surrounding a retroverted well at the end of the lamp bulb.

3. In a process for producing a tubular photofiash lamp closed at one end by an exhaust tip, the steps of:

(A) sealing a lamp-mount structure comprising leadin wires into one end of a glass lamp tube to form a stem-press base thereof, with the mount structure having ignition means including a filament wire at its end inside the lamp and allowing for electrical contact means with its ends outside of said lamp,

(B) applying through the open other end of the lamp tube a quantity of primer material onto a portion of the lead-in wires located Within the lamp tube so that the primer material contacts the filament wire,

(C) introducing into said lamp tube through said open other end a quantity of combustible material,

(D) positioning the combustible material int-o the portion of the lamp tube adjacent to the sealed end,

(E) heating to a plastic condition and attenuating a portion of the lamp tube intermediate to the portion containing the combustible material and the open other end to form an attenuation and to define a lamp bulb which is the portion of the lamp tube 4. The process of claim 3 in which the tipping off between the stem-press base and the attenuation, of step I is conducted while the lamp is at low tempera (F) blowing a gas into the open end of the lamp tube tures materially below room temperature in order to ob- While heating the conjuncture of the attenuation with tain a resulting fill pressure in the finished lamp substanthe lamp bulb to form a convex dome on the lamp, 5 tially above atmospheric.

(G) after the attenuation has cooled to the point of 5. The process of claim 4 in which the lamp has been becoming rigid and while the dome of the lamp is cooled to the said low temperatures by immersing the still hot enough to be plastic, moving along their bulb in liquid nitrogen. common axis relatively towards each other the attenuation and the lamp bulb so that the open end of 10 References Cited y the Examine! the lamp bulb at the contraction takes the form of UNITED STATES PATENTS a retroverted well surrounded by a reentrant raised rim with the attenuation arising from approximately the center of the well,

(H) exhausting the lamp bulb and introducing into it through the open other end a combustion-support- References Cited by the Apphcant ing gaseous medium (I) heating and closing by tipping off the contraction 736,231 3 /1905 M D lL close to the end of the lamp bulb to hermetically seal off the lamp bulb, forming an exhaust tip and RICHARD H. EANES, JR., Primary Examiner. a lamp.

2,956,372 10/1960 Madigan -34 3,113,010 12/1963 Willis 65-108

Claims (1)

1. 3. IN A PROCESS FOR PRODUCING A TUBULAR PHOTOFLASH LAMP CLOSED AT ONE END BY AN EXHAUST TIP, THE STEPS OF: (A) SEALING A LAMP-MOUNT STRUCTURE COMPRISING LEADIN WIRES INTO ONE END OF A GLASS LAMP TUBE TO FORM A STEM-PRESS BASE THEREOF, WITH THE MOUNT STRUCTURE HAVING IGNITION MEANS INCLUDING A FILAMENT WIRE AT ITS END INSIDE THE LAMP AND ALLOWING FOR ELECTRICAL CONTACT MEANS WITH ITS ENDS OUTSIDE OF SAID LAMP, (B) APPLYING THROUGH THE OPEN OTHER END OF THE LAMP TUBE A QUANTITY OF PRIMER MATERIAL ONTO A PORTION OF THE LEAD-IN WIRES LOCATED WITHIN THE LAMP TUBE SO THAT THE PRIMER MATERIAL CONTACTS THE FILAMENT WIRE, (C) INTRODUCING INTO SAID LAMP TUBE THROUGH SAID OPEN OTHER END A QUANTITY OF COMBUSTIBLE MATERIAL, (D) POSITIONING THE COMBUSTIBLE MATERIAL INTO THE PORTION OF THE LAMP TUBE ADJACENT TO THE SEALED END, (E) HEATING TO A PLASTIC CONDITION AND ATTENUATING A PORTION OF THE LAMP TUBE INTERMEDIATE TO THE PORTION CONTAINING THE COMBUSTIBLE MATERIAL AND THE OPEN OTHER END TO FORM AN ATTENUATION AND TO DEFINE A LAMP BULB WHICH IS THE PORTION OF THE LAMP TUBE BETWEEN THE STEM-PRESS BASE AND THE ATTENUATION, (F) BLOWING A GAS INTO THE OPEN END OF THE LAMP TUBE WHILE HEATING THE CONJUNCTURE OF THE ATTENUATION WITH THE LAMP BULB TO FORM A CONVEX DOME ON THE LAMP, (G) AFTER THE ATTENUATION HAS COOLED TO THE POINT OF BECOMING RIGID AND WHILE THE DOME OF THE LAMP IS STILL HOT ENOUGH TO BE PLASTIC, MOVING ALONG THEIR COMMON AXIS RELATIVELY TOWARDS EACH OTHER THE ATTENUATION AND THE LAMP BULB SO THAT THE OPEN END OF THE LAMP BULB AT THE CONTRACTION TAKES THE FORM OF A RETROVERTED WELL SURROUNDED BY A REENTRANT RAISED RIM WITH THE ATTENUATION ARISING FROM APPROXIMATELY THE CENTER OF THE WELL, (H) EXHAUSTING THE LAMP BULB AND INTRODUCING INTO IT THROUGH THE OPEN OTHER END A COMBUSTION-SUPPORTING GASEOUS MEDIUM, (I) HEATING AND CLOSING BY TIPPING OFF THE CONTRACTION CLOSE TO THE END OF THE LAMP BULB TO HERMETICALLY SEAL OFF THE LAMP BULB, FORMING AN EXHAUST TIP AND A LAMP.

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