US2185981A - Contactor base for electric lamps, tubes, and the like - Google Patents

Description

con-uc'roa BASE FOR ELECTRIQ LAMPS, TUBES, AND THE LIKE Jan 2, 1940 c. w. HALLER 2 Sheets-Sheet 1 Filed April 10; 1939 CYRUS W HALLER,

INVENTOR. M

ATTORNEY.

Jan. 2', 1940. I c. w. HALLER 2,185,981

CONTACTOR BASE FOR ELECTRIC LAMPS, TUBES, AND THE LIKE Filed April 1'01 1939 2 shedshea 2 CYRUS W. HALLER,

' INVENTOR.

ATTORNEY.

' rhesus it 2, 1940 a "new con'rsc'ron BASE son. Ema-mic LAMPS, 'ronns, AND 'rnn LIKE 'Cyrus W. Haller, Marblehead, Mass, assignor to Hygrade Sylvania Corporation, Salem, Mass., a corporation of Massachusetts Application April 10,1939, Serial No. 287,025

6 Claims. (cl- 178-32) This invention relates to contactor bases and more particularly to bases for electric lamps, radio tubes and similar devices.

A principal object of the invention is the pro- 6 vision, for such devices, of a screw base in which an insulating cup is the main support of the base and carries the necessary metal contact pieces intimately bonded to its surface.

Heretofore in the manufacture of incandescent 10 electric-lamps of the conventional screw-base y the base consists of a previously threaded metal shell insulatingly carrying at the bottom a metal contact button. This button is usually insulated from the shell by arelatively shallow lls vltreous cup-like ring which is fused to the shell and to the contact button. The'flnished'base is then usually cemented to the lamp bulb by a relatively narrow ring of cement, thus leaving the greater part of the inner face of the shell exposed. when such a base is employed in connection with a fused lead-in wire there is considerable danger of the gases and vapor released by the blowing of the fuse, causing a destructive are within the base. There is disclosed in' U. S. Patent No. 35 2,141,146, issued December 20, 1938, to R. M.

Zabel, a method of protecting the normally exposed inner face of the shell by extendingthe glass skirt upwardly. Accordingly, another object of the present invention isto provide an imgar-proved method of insulating substantially the entire inner face of the usual threaded metal con-- tactor base, while'atthe same time improving the mechanical construction and appearance of the base.

'llhe improvement in mechanical construction is obtained by using the insulation for the interior of the shell as the main supporting member of the base. This is done bymolding a cup-shaped insulating member to substantially the shape of %-the finished base and intimately bonding to its surface metal contact pieces thin enough to conform closely to said surface. This canbe accomplished by molding the insulation and the metal pieces simultaneously in a single unit as describedgg hereinafter: by molding the insulating cup and then depositing the metal on it by electrolysis orby spraying; or by any similar process.

a construction permits the use of a thinbase 0111mm 5.

cause. the dimensions are fixed by the molding process.

A further object of the invention is the provision of a lamp or tube base with a threaded metal contact supported-or embedded in insulat- 6 ing metarials which have hitherto not been found practicable for this purpose. .Among such mate! rials may be mentioned particularly, the plastics of the thermosetting type, such as Bakelite and similar phenolic condensation products. Such in- 10' sulators will not chip, or crack, and are capable of more accurate molding, than is the usual glass insulator.

A feature of-the invention is a base in which can readily be incorporated continuous, discon- 16' tinuous or special threads for identification or theft-proof purposes.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detailed descriptions and the appended claims. i

While the invention will be described herein in connection with the manufacture of a screw-base for lamps, it will be understood that the base is equally well adaptable to radio tubes, resistors, fuses, plugs and similar electric devices which are designed to be connected into the conventional screw-threaded lamp socket or the like. Accordingly in the drawings:

Figure 1 is a vertical cross-sectional view of a typical molding device for carrying out the method according to the invention.

. Figure 2 is another view of the apparatusof Figure 1. showing the molding die in its molding 45 position. I

Figure 3 is a partial sectional view of a typical form of thin walled metal shell that is used with the molding device of Figures 1 and 2.

Figure 4 is a bottom ,plan view of Figure 3. Y 50 Figure 5 shows one form of base according to the invention. h

' Figure 6 isa perspective view of the particular type of shell blank that is used in producin'g'the PATENT OFFICE Figure 7 shows a type of base produced using the shell blank of Figures 2 and 3.

Figure 8 shows a modified form of base according to the invention, with discontinuous screw threads.

Figure 9 shows a bottom plan view of Figure 8.

Figure 10 shows a further modification of the' base.

Figure 11 is a view of a modified form of die that may be used in the manufacture of bases for certain types of mechanically based bulbs.

Figure 12 is an exploded view of a bulb and its co-operating base formed in accordance with the invention and using the die of Figure 11.

Figure 13 shows a base similar to the base of Figures 1 and 2 and provided with a locking recess therein.

Figure 14 shows a modification of the base of Figure 5.

Figure 15 shows a modification of the shell blank of Figure 3. Referring to Figures 1 and 2, the numeral I represents a mold made of any suitable material and is provided with a substantially cylindrical smoothfaced mold cavity 2, the bottom of which is recessed as indicated by the numeral 3, and the cylindrical wall of which is provided with a round screw-thread I. Preferably the thread 4 is designed so that when the base is formed as described below, the base threads are of the pitch and shape ordinarily employed on incandescent lamp bases. Themold I, may be of one piece but is preferably of two pieces suitably fastened together. Co--operating with the mold I, is a specially shaped die or plunger having its forward end tapered as indicated bynumeral 6, and terminating in a cylindrical tip I. The main body portion 8 of the die is preferably cylindrical and joins a'flared portion 9, which in turn joins a shouldered portion l 0. The cylindrical portion 8 is of smaller diameter than the inside diameter of the mold cavity, the difference in diameters depending upon the thickness of the insulation wall desired in the finished base.

Any well-known form of heating means (not' shown) may be provided for bringing the mold to the proper temperature for setting. For Bakelite this temperature is about 350 C.

In order to form the base, there is positioned within the mold cavity a thin-walled metal shell or cup I I (Figs. 3 and 4) of brass or other suitable metal such as is ordinarily employed in the manufacture of screw-bases for incandescent lamps. After the metal shellis placed in the mold, a cylindrical pellet I2 of a suitable heat-hardening,

often called thermosetting, plastic insulation material may be employed. As examples of materials that are useful for this purpose may be mentioned, powdered Bakelite or similar condensation product either alone or mixed with 'a ceramic powder, asbestos powder or the like. If desired the pellet may consist entirely of a suitable compressed powdered ceramic such as porcelain, Isolantite or the like, ,to which'has been added a heat-hardening, often called thermosetting, binder which becomes plastic when subjected to the molding temperature and pressure.- Preferably, although not necessarily, the pellet is provided with a central opening l3, and the bottom face of the pellet is recessed at II to receive the usual eyeletted metal inset 20. When the mold is heated to the proper'temperature the die is moved downwardly and subjected to suitable pressure to cause the pellet to become plastic and fill the space between the die and the inner face of shell II. At the same time. the die forces'the button I5 down against the bottom of recess 3, I

breaking the ribs 49, which join the eyelet button to the remainder of the metal shell, and also forces a quantity of the plastic insulation throughthe circular opening I6 in shell II causing this insulation to assume the shape of the said recess as shown clearly in Figure 2. The pellet is so proportioned in volume that when the die reaches its lower-most position as shown in Figure2, there is a suflicient quantity of the plastic insulation to provide the desired thickness to the wall II. It will be understood that when the die first engages the pellet it causes the shell I I to be firmly held against the portion I8 of the mold so that further downward movement of the die forces the plastic insulation upwardly between the die face and the shell. Furthermore the close flt between the shoulder I on the die, and the cylindrical wall-portion I9 of the mold, prevents the plastic insulation from being forced upwardly beyond the rim of shell II.

I have found that if the shell I I is of sufficiently thin metal stock, the die pressure is transmitted through the insulation I! to cause the wall of .the shell to conform itself to the threaded surface of the mold, consequently the shell is formed with the screw-thread at the same time that a corresponding thread in the insulating wall I! is formed. Preferably the die tip I is of about the same length as the eyelet 20 so that the die engages the rim of the eyelet. and prevents the plastic insulation from, flowing through the eyelet. When the base has been formed as described, the die is removed and the insulation is allowed to harden whereupon the two halves of the mold may be opened and the finished base removed. The base will then be found toconsist of an internal cup-like insulating shell the outer surface of which is appropriately threaded and the correspondingly threaded metal shell II is in intimate bonding contact with the insulating shell over its entire threaded area. The contact button I is also bonded to the insulating shell and the eyelet 20 is accurately centered on the vertical axis of the base. ,Also the insulating shell is formed with a smooth conically inclined wall 2| communicating with the eyelet, and the slant of wall 2| may be such as to facilitate the insertion of the usual lead-in wire through the eyelet thus enabling the base to be conveniently used on any well-known type of automatic machine for applying the base to a'suitable lamp or tube bulb.

From the foregoing it will be seen that by choosing a suitable insulation material for the pellet I3, it is possible to impart a very pleasing appearance to the finished base as the insulation may be made in any desired color or combination of colors. Furthermore, it is possible to form .the base with greater accuracy than is possible where a pre-threaded metal shell is employed and fastened to the eyeletted button by the usual shallow glass ring. It is also possible by this method of base formation to employ insulating materials which are not adaptable to the usual methods of forming bases. Thus it is possible to produce a base wherein-the exteriorly exposed portion of the insulation is substantially chipproof. Furthermore, the portion 22, being integral with the wall portion II provides a rigid support for the shell I I, both against vertical as well as against radial crushing. It will. be understood.

'of course, thai if desired the recess 3 in the mold may be made as deep as is found necessary to provide the requisite spacing between the lower rim of shell I I and the metal button I5.

shell is formed with a series of thread-sectors 23 on one side and a similar series of thread-sectors 24 on the opposite side, it being understood that the sectors are in eifect sectors of what would otherwise be a single continuous thread such as is shown, for example, in- Figs. 2 and 14, the intermediate unthreaded portions of both the metal 25 and the insulator shell 26 being cylindrical. The eyeletted metal contact button 21, is integrally bonded to the extension, of the insulator shell as described in connection with Figs. '1

and2.

If desired, the thread-sectors may be so formed during the molding process that the base is capable of being turned readily in one direction into the usual threaded socket, but is incapable of being turned in the opposite direction. Thus, as shown in Fig. 10, the thread sectorsare formed with pointed inclined ends 29, 30, which do not interfere with the rotation of the base into the usual threaded socket, but which lock against the socket threads when the base is turned to remove it from the socket. -It will be understood, of course, that the base may be molded with any other form of mutilated thread, and while the sectors may be formed;

In Figure 2, the ribs 49, which unite the eyeletted button to the main metal shell of Figs. 3 and 4, have been broken by the molding process to separate the eyeletted contact button and the cylindrical metal shell. The portion of the ribs remaining with the contact button will be set into the molded insulation shell, serving as addi-, tional anchors for the contact button.

Instead of employing a metal shell in the form of a complete cylinder, as shown in Figs. 3 and 4, the shell may be made in skeleton form, such as shown in Fig. 6 comprising a rim 34 formed with a set of spaced strips 35. The manner of. using this skeleton shell is the same as that described in connection with Figs. 1 and 2, and the finished base thus produced is shown in Fig. 5. In this embodiment the vertical strips 35 are imbedded in the insulation shell 36 and each strip is molded at the same time the insulation shell is formed so that both the shell and the strips have the required threads therein. It will be obvious that instead of employing the strips 35, as integral extensions of the rim 34, the stripsalone may be employed and held in the mold in any suitable manner in circumferentially spaced relation so that when the insulation pellet is subjected to heat and pressure the strips imbed themselves in the molded insulation shell, and are flush with the outer face of the insulation shell.

In the foregoing embodiments of the invention the insulator portions 2 i 26 etc., are molded with a substantially smooth inner surface and the bases are capable ofbeing fastened to the lamp or bulb by a bonding cement or the like in the usual manner. However, the process is also applicable to the control-of the configuration of the internal surface as well as the external surface Figs. 1 and 2.

or the insulatorshell. For example, in lamps-of these-called mechanically based type, the portion of the lamp bulb adjacent the seal may be provided with integral screw threads, depressions,

beads or the like which are' arranged to' interlock 1 with corresponding threads, depressions, beads, etc., on the internal surface of the metal shell base. Examples of such mechanically based lamps areillustrated in U. S. Patent No. 2,028,- 884, issued January 28, 1936 to R. B. Thomas.

vReferring to Figs. 11 and 12, a description will be given of the manner of applying the process to the manufacture of one illustrative form of me: chanically based bulb.

Asshown in Fig. 12, the bulb 3'l has its butt portion-l8 provided with raised thread sectors, 39 preferably, although not necessarily, of the configuration shown. I Whilethe drawings show only one set of thread sectors, it will be understood that a' similar set or sets maybe provided around the periphery of the butt 38 and these sectors may, if desired, be molded at or during the 'operationof sealing the reentrant stem 40 into the bulb. The base which is shown in section in .the lower part of Fig. 12 may besimilar to the bases shown in Figs. 5, 7, 9, 10, l3, l4, and may be manufactured in accordance with the process described in detail in connection with The only difference is that in place of the smooth-faced die 8, there is em-' ployed a die such as shown in Figure 11 which has its cylindrical face provided with recessed thread sectors ll to correspond to the thread sectors 39 on the lamp butt 38, thus forming the insulator shell 42 with correspondingly raised sectors 13'. The base may then be threaded on to the butt 38 and fastened in-any suitable manner. Thus the lead-in wire N may be bent back upon itself and the free end soldered to the rim of the metal shell 45. It will be obvious that instead of molding the internal face of the insulator shell 42 with thread sectors the die may have its cylindrical face formed with a continuous recessed plural turn screw-thread and the butt 38 may likewise be provided with a continuous plural turn raised screw-thread with a transverse slot to receive the bent back lead-in wire 44 inthe manner illustrated, for example, in Patent No. 1,650,289 to J. B. McGinley. In carrying out the process in connection with the type of base shown in Figure 12, it may be necessary to make the die in sectors which may be collapsed or removed in order to allow for the removal of the finished base from the die. It will be understood, of course, that the embodiment of Figure 12 is merely illustrative of one particular configuration for the internal wall of the insulator shell.

'In certain cases, it is desirable to provide a bulb with a base that is capable of receiving a locking member when the bulb is inserted in the receptacle. Thus, as shown in Figure 13, the base which may be of any of the forms disclosed in the preceding figures has its external threaded surface molded with a recess or slot 46 to receive a locking screw or projection (not shown) for preventing the bulb being removed from its 'Instead of employing a cylindrical shell or skeleton shell (Figure 5), the side contact of the base may consist of a simple strip of metal 41, which may be held in the mold in any convenient manner so that when the die forces the plastic insulation to shape, the strip will be embedded in the plastic and the base will consist for the most part of an externally threaded shell 48, of the insulation having embedded in its outer face the correspondingly threaded metal strip 41. Instead of employing a seamless metal shell ll (Figures 3 and 4), for forming the base, this shell may be made from a strip of the metal having its edges overlapped as indicated in Figure 15.

As an alternative method, the metal shell ll may be omitted and after the insulation is molded to the desired formation with the button or eyelet 20 thereon, as described in connection with Figures 1 and 2, the desired portion or por-- tions of the outer surface of the molded insulator shell may be provided with a coating of conductive material as by spraying, dipping, electrolytic deposition, painting or the like.

It will be understood that the invention is not limited to the use of metal sheet stock for the shells H, 25, 34, and that the' metal mesh, perforated metal or any form of foraminous metal stock may be employed. Other changes and modifications may be made in the embodiments disclosed, without departing from the spirit and scope of the invention.

This application is in part a continuation of my application Serial No. 52,286, filed November 30, 1935, and issued May 9, 1939, as U. S. Patent No. 2,158,044. I

What I claim is:

1. A contactor base for lamps and the like, said base comprising a main hollow cup-like thinwalled member of thermally-set insulation, the cylindrical portion of said member containing screw threads on the cylindrical portion of its external surface, a correspondingly threaded thin metal cylindrical shellintegrally bonded to said surface, said metal shell extending to but not beyond thetop of the cup-like member and extending toward but spaced from the bottom of said cup-like member, an eyeletted flat metal contact disk integrally bonded to the bottom of said cup-like insulating shell and out of contact with said metal shell, the eyelet in said disk being in register with a small hole in the bottom of the insulating shell and being flared outward in the insulating shell for bonding purposes, the eyelet extending upward into the circumference of the hole, the disk having small ribs extending from its circumference upward into the insulating cup for bonding purposes, the cup-like shell of insulation being flared outward at its top to meet the top of the cylindrical metal shell.

2. The combination of claim 1, in which the metal shell is too thin to be rigidly self-supporting of itself, the insulating cup combining with it to form an integrally self-supporting structure in combination.

3. The combination of claim 1, in which the metal shell is too thin to be rigidly self-supporting of itself, the insulating cup combining with it to form an integrally self-supporting structure in combination, and in which the combined structure is integrally slotted transversely of its threads. i

4. The combination of claim 1, in which the metal shell is too thin to be rigidly self-supporting of itself, the insulating cup combining with it to form an integrally self-supporting structure in combination, and the combined structure is integrally slotted transversely of the threads, and in which the insulating cup-like member bears parts of threads on its interior surface, the parts of threads being arranged to,fit corresponding parts of threads on the neck of an incandescent lamp bulb.

5. The combination of claim 1, in which th main hollow thin-walled member of thermallyset insulation has its hollow interior in the form] of a cylinder terminating at its bottom in a cone providing a slanted surface to facilitate the insulation of a lamp lead-in, wire. 6. A metal blank for use in lamp basemanufacture comprising a thin" walled cylindrical metal shell terminating ina substantially flat v surface at one end of the cylinder, the other end being open to form a cup-like shell, the bottom-

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