US1360152A - Method of basing incandescent lamps - Google Patents

Description

A. SWAN. METHOD OF BASING INCANDESCENT LAMPS.

APPLICATION FILED SEPT. 30,1918.

Patented Nov. 23, 1920.

Fig. 4.

Inventor: Alfred Swan, /1&4. M

His ALLoT-neg.

UNITED STATES PATENT OFFICE.

ALFRED SWAN, 0F MONTCLAIR, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

METHOD OF BASIN G INGANDESCENT LAMPS.

Specification of Letters Patent. Patented N 23 1920 Original application filed June 20, 1917, Serial No. 175,868. Divided and this application filed September 30, 1918. Serial No. 256,351.

T 0 all toll-0m it may concern.

Be it known that I ALFRED SWAN,-L subject of the King of (irreat Britain, residing at Montclair, county of Essex, State of New Jersey, have invented certain new and use ful Improvements in Methods of Basing Incandescent Lamps, (this application being a division of my prior application Serial No. 175,868, filed June 20, 1917,) of which the following is a specification.

My invention relates to providing incandescent lamps and similar evacuated glass vessels with metal bases cemented to the glass bulb and soldered to leading-in wires which conduct current to the interior of the vessel.

One object of my invention is to improve and cheapen the basing of incandescent lamps and similar articles. A further object is to simplify and improve the method of applying the base to the lamp and soldering the leading-in 'wires tothe base. To these ends .I utilize the heat of the exhaust oven for'cementing the bases to the bulbs, and may also utilize it for soldering the leading-in Wires to the base. I prefer to use a cement which has the property of first softening when heated, and then hardening permanentlyupon continuing the heating to temperatures such as are commonly used- 7 during the final stages of the exhaustion of incandescent lamps. I prefer to use a cement which will stand for many weeks exposed to the air without losing the properties which make it suitable for use in basing lamps, and hence the lined bases'need not be used immediately, so that bases may be prepared and then stored for a considerable period of time if desired.

The novel features of my invention are pointed out with particularity in the appended claims but for'purposes of illustration I have shown in the accompanying drawings one of the various forms in which my invention may be embodied and in which Figure -l is a longitudinal section of a lamp base of the usual type lined with cement;

'Fig. 2 is a view of a lamp showing the base in section and in the position it assumes,

when the cement softens, with pellets of sol- 'der in position to secure the leading=in wires to the base; Fig. 3 is a longitudlnal section of one form of,an exhaust oven suitable for -practising my invention; Fig. 4 is a longitudinal section of an improved form of base particularly suitable for use in this improved method of basing lamps; and Fig. 5 is a top view of Fig. 4.

For purposes of illustration, I have shown in Fig. 1 a lamp base of the usual type comprising a tubular threaded shell 1 havingat one end a slightly countersunk perforation 2 and closed at that end by a glass Web 3 which carries a center contact 4 with a sli htly countersunk perforation. In accor ance with my invention, I apply to the inner edge of this base a layer of cement 5. The base lined with cement is applied to the lamp, with the leading-in wires 6,"as shown in Fig. 2, threaded through the perforations in the shell 1 and the center contact 4. Solder which will melt at the temperature attained in the exhaust oven during exhaust, and which is preferably in the form of pellets 7, is placed in the perforations in juxtaposition to the leading-in Wires, so that when the solder melts it settles into the countersunk perforations in the base and solders the leading-in Wires to the contacts.

The lamp with the base and the leading-in Wires arran ed as shown in Fig. 2 is exhausted in t e usual way. During exhaust the lamp must be heated to a high temperature to obtain a ood vacuum, and I utilize this unavoidable eating to cement the base to the bulb, and may also use it to solder the leading-in wires to the base, thereby securing a marked saving in time, labor and machinery. Any suitable form of exhaust oven may be used, such as that illustrated in Fig. 3, in which a removable cover 8 can be raised to permit the operator to insert the exhaust tube of a lamp intoa pump connection 9 which grips the exhaust tube and holds the lamp in the vertical position as shown, with the base on the upper end. To prevent tarnis ing of the bases and also to settle the bases squarely upon the bulbs, I provide metal base shields 10 in the form of loosely mounted cups which fit over the bases and which can move downward as the cement 5 softens and press the bases firmly into'true position on the lamp.

After the lamps" are connected to the pump and are in position the cover 8 of the exhaust oven is lowered, the lamps exers 12. As the temperature of the oven rises, the cement softens, the bases settle down snugly on the bulbs, and the solder melts, so that by the time the lamps are exhausted the bases are cemented in position, and the leading-in wires are soldered to thebase. Other forms of exhaust ovens and apparatus may, of course, be used and the particular form shown is merely illustrative.

A suitable cement which I prefer to use in accordance with my invention may be made with materials having the properties of the condensation product of phenol and formaldehyde obtainable on the market under the name of bakelite. This material will dissolve in various volatile solvents, has has the property of becoming soft and sticky at about 200 (3., and at about 3009 C. is permanently converted into a hard infusible compound. As. this material shrinks considerably in hardening it may crack the glass and to prevent this I mix it with an inert filler, such as marble flour or similar powdered material. For example, I may use one part of bakelite, from one to two parts of rosin, and from 8 to 10 parts of marble dust or similar inert filler, with sufficient solvent, such as wood alcoliol, to render the cement plastic and easily handled. The proportions above given are by weight and preferably the dry materials are weighed,

thoroughly mixed, and then the solvent is added.

The novel form of base shownin Figs. 4 and 5 is particularly suitable for use with my invention. This base comprises a tubular shell 1 of the usual form, and a molded web 13, which may be made -of bakelite or some similar material permanently hardened by heating, before being placed in position in the shell 1, but is preferably made of glass or refractory material, particularly when the temperature of the exhaust oven is high, as at about 100 C. the finish on a bakelite web is injured. This web carries an annular contact 14, a perforated center contact 15, and a ring of cement 16 for securing it to the. shell. These webs can be molded very quickly and cheaply with the contacts 14 and 15 in place in them. The base with the ring 5 of cement in itis assembled by slipping the web 13 into place in the shell 1, the assembled base placed on the lamp with the leading-in wires threaded through it, and the lamp is exhausted as previously described. The heat of the exhaust oven causes the cement 16 on the web 13 to harden and firmly cement the web to the shell 1, while at the same time the cement 5 firmly cements the shell to the glass of the lamp. In this way the operation of fastening the web into the shell and base to the lamp are performed simultaneously.

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

1. The method of exhausting a bulb and simultaneously cementing a metal member to the bulb which consists in applying to the juxtaposed surfaces of said member and said bulb a cement which softens and becomes adhesive at a temperature between room temperature and the temperature at which glass softens. exhausting said bulb, and heating said bulb and member during exhaust to a temperature sufficient to soften said cement.

2. The method of simultaneously basing and exhausting a bulb which consists in exhausting the bulb, heating the bulb during exhaust, and cementing the base to the bulb during exhaust by means of a layer of cement which is interposed between the base and bulb and which softens and becomes adhesive at the temperature attained by the bulb and base during exhaust.

The method of basing a bulb which consists in connecting the bulb to an exhaust pump, applying to the bulb a base provided on its inner walls with a layer of cement which softens at about 200 C. and permanently hardens at about 300 C., and raising the temperature during exhaust from room temperature to above 300 C.-

and thereby softening and then setting said cement.

4. The method of exhausting and basing an evacuated bulb which consists in connecting the bulb to an exhaust pump, applying to the bulb a base having an inner layer of a cement comprising a partial condensation product of phenol and formaldehyde capable of being transformed by heat into a hard infusible form and having a filler to render the shrinkage of said cement substantially the same as that of the glass, and heating said bulb during exhaust to a temperature at which said cement sets by transformation of said product into the hard infusible form.

5. Means for exhausting and basing a bulb comprising an exhaust connection for holding the bulb and connecting the exhaust tube of the bulb to an exhaust pump, a support normally opposite said connection during exhaust, and a metal cap shaped to fit overtlie base of the lamp and mounted in said support to move freely toward said connection to press the base down upon the bulb.

6. An exhaust oven for incandenccnt lamps comprising an exhaust connection to the exhaust pump adapted to hold the lamp in the oven in a vertical position with the base up, means for heating the oven, and a tubular shield for fitting over the base and mounted in said oven directly above said connection to move vertically with the base.

In witness whereof I have hereunto set my hand this 23d day of Se tember, 1918.

ALF ED SWAN.

Images