US3093434A - Molded plug - Google Patents

Description

June l1, 1963 w. R. FRANCIS 3,093,434

MOLDED PLUG Filed Jan 4. 1960 3,093,434 MLDED PLUG Wallace R. Francis, New Haven, Conn., assignor to General Electric Company, a corporation of New York Filed Jan. d, N60, Ser. No. 26S 9 Claims. (Cl. 339-195) The present invention relates to molded Wiring devices such as connectors, and more particularly to electrical connector plugs and the method of manufacture thereof.

Prior art wiring devices, such as electrical connector plugs, have ybeen economically and expeditiously manufactured by molding a single insulating body around lche connections formed between terminal portions of the contact blade members and the bared conductor ends, and the area adjacent thereto. This body is made of a molded insulating material like rubber or some yother suitable thermoplastic or thermosetting material, such as for example, one of the vinyl molding compounds. The physical and electrical proportions and characteristics of such an insulating body vary widely in accordance with the application for which it is designed. Such a body should invariably, however, have good insulating qualities, be physically strong, and have a neat and compact overall appearance.

In molded cordset plugs of :the prior art, stranded multiple wire conductor has been widely used. This type of conductor, as is well known in the art, is rugged and durable, due to the improved flexibility of the stranded conductor wires, and it therefore lconveniently lends itself to numerous applications. When the bared end of a stranded conductor has been attached to the terminal portion of a plug contact blade, a problem sometimes occurs when the insulating body is molded about the terminal connections and the adjacent terminal and conductor portions to form the finished plug. More particularly, the high pressures which evolve during the molding operation sometimes cause the exposure of one or more strands of the conductor on the surface of the molded plug `or result in their being in dangerous proximity thereto. These strands may be forced to the surface or dangerously near to the surface during the molding process and some of them may be electrically energized when the plug is placed in service. In addition, the high molding pressures may also cause the loose strands of one stranded conlductor to be forced laterally toward the loose strands fof another conductor, or toward the terminal portion of the contact blade of this other conductor. Such disarrangemen-t of strands may, of course, create the possibility of short circuiting within the plug body. There are numerous precautionary steps that may be taken during the manufacture of a molded electrical plug to eliminate the loose strand problem, such as using inserts which serve as separators and containers for each connection and its associated bare conductor end. However, no app-roach has been utilized, heretofore, which lends itself to the economical manufacture of a molded plug, while at the same time enhancing its physical strength and overall appearance.

Accordingly, it is a general object of this invention to provide an improved wiring device, which has improved insulating characteristics.

Another object of my invention is to provide an improved electrical connector which has very good insulating characteristics, is physically strong, and has a neat and compact overall appearance.

A further object of my invention is to provide an `irnproved electrical connector plug which incorporates an insulating housing that is formed by a two-step molding process.

An addi-tional object of my invention is to provide an Patented June 11, 1963 *ice 2 improved electrical connector plug having an attractive and relatively inexpensive outer appearance.

In carrying out one aspect of my invention, I have provided an electrical connector plug 'having a plurality of spaced contact blades. Each of these contact blades has a contact portion and a terminal portion. A conductor is mechanically and electrically connected to the terminal portion of each of the blades to form a plurality of spaced connections. An inner body of molded insulating material surrounds each connection and also covers adjacent areas of blade and conductor. An aperture is formed in this body between the spaced connections and their adjacent bared conductors. An outer body of molded insulating material surrounds the inner body and i-t extends through the aperture to further insulate the connections. By using two separate molded insulating lbodies for my improved plug, a very sturdy plug structure is obtained and any loose conductor strands or disarranged conductor is prevented from coming too close to the outer surface of the plug or tending to short circuit within the plug. In addition, this plug structure facilitates llexibihty in the selection lof molding materials. As an example of this flexibility, a relatively inexpensive molding anaterial may be used for the inner ybody and a more expensive and attractive colored molding material might ybe used for the louter body.

Further aspects of my invention will become apparent hereinafter, and the specification concludes with claims particularly pointing out and distinctly claiming ythe subject matter which I regard as my invention. The invention, however, as to yorganization and method of utilization, together with further objects and advantages thereof, may best `be understood by reference to the following description when taken in conjunction with the accompanying drawing in which:

FIG. 1 is an elevational view of a pair of contact blades with -the bared conductor ends of a two-conductor rip cord attached thereto;

FIG. 2 is an elevational view of the contact blades and bared conductor ends of FIG. l after a premo-lded inner body of molded insulating material has been formed around portions thereof;

FIG. 3 is an elevational view, partially in section and partially broken away to show the external and internal construction of an improved connector plug embodying my invention;

FIG. 4 is an elevational view, partially in section, showing the relationship between the inner and outer insulating bodies;

FIG. 5 is a perspective view of an improved electrical connector plug embodying my invention;

F IG. 6 is an elevational View, partially in section, of an improved angle plug embodying my invention in alternate form thereof;

PIG. 7 is a bottom view of the angle plug of FIG. 6, partially in section; and

FIG. 8 is a perspective view of the improved angle plug embodying my invention.

Referring first to FIG. l of the drawing, there is illustrated a pair of plug contact blades I. Each of these contact blades 1 is of one-piece spring strip construction and includes a at metal strip which is folded upon itself at the outer end to provide a spring acting outer contact portion 3 and a relatively fixed terminal portion 5. (See also FIG. 2.) The outer contact portion 3 of each blade has a pair of aligned holes 7 for engaging the usual projections of a mating female receptacle. Terminal portion 5 of each contact blade 1 includes an integral means such as tab extensions formed thereon, for securing the bared end of a conductor thereto. As shown in FIG. 1, I have chosen conductors 9 to illustrate this aspect of my invention, and these conductors are part of a two-conductor rip cord 11. Each conductor 9 includes a number of stranded wires 10 which are surrounded by the tab extensions of the contact blades to physically and electrically attach them thereto at connections 6 in the well-known manner.

Turning now to a significant aspect of my invention, in examining FIGS. 2-4, it will be noted that a single molded insulating body is not formed around connections 6 as is the conventional custom. In my improved connector plug, I have formed an intermediate or inner body 13 around these connections, before forming my finished plug 15 therefrom. (See FIGS. 3 and 4.) Body 13 individually surrounds each connection 6 and its associated bared conductor end with molded insulating material. Aperture 16 is also formed in the inner body between each connection 6. (See FIG. 2.) This aperture may be of any suitable configuration, such as a notch or a slot, but for purposes of illustratingy my invention, the configuration of the aperture is in the form of an isosceles triangle. Base 17 of this triangular aperture is spaced slightly from and generally parallel to front wall 19 of body 13, as shown in FIG. 2. This leaves strengthening rib 20 extending parallel to and adjacent to outer wall 19. The apex 18 of aperture 16 is adjacent to and disposed between the ends of the integral insulation of each conductor. Triangular aperture 16 thus physically separates connections 6 and their associated bared conductor ends. It will also be noted that I have formed a shallow central recess 21 in the outer face of front wall 19. 'Ihe purpose of this recess shall hereinafter become apparent. Body 13 may consist of a relatively hard plastic material which is of low cost, such as polystyrene. Of course, any other suitable molding material could be also used, such as, for example, polyvinyl chloride. The type or color of insulating material which is used in this premolded body 13 may vary widely depending upon the application for which the connector plug 15 is to be used.

For parting conductors 9 of the rip cord angularly in the direction of their respective attached contact blades 1, I have molded angular surfaces 23 into body 13. These surfaces 23 are disposed so as to provide an acute angle from outwardly projecting edge 24, for securely and rigidly supporting the parted conductors of the rip cord within molded body 13.

Body 13 may be formed by any suitable premolding operation, such as injection molding. Any loose strands of bared conductor 10 which are forced to the surface of inner body 13 during the premolding operation would of necessity be adjacent to or contiguous with the outer surface of body 13. To illustrate this, in FIG. 2, loose conductor strands a and b have been indicated in the vicinity of the outer surface of inner body 13. The premolding operation contains such loose strands as these within the limits of the premolded body 13. Any laterally extending loose conductor strands, such as indicated by c and d of FIG. 2, which might otherwise be forced together and touch or short out within the plug, are also physically separated by aperture 16 of the inner body. Aperture 16, therefore, performs an important function in my plug, by eliminating the possibility of short circuiting therein.

After premolded body 13 has been formed around connections 6 and their associated bared conductor ends, my invention includes the benefit of providing a subsequent or final molding operation. Any suitable molding operation may again be used, such as injection molding. After the premolded body 13 has been formed, to provide a further insulating support for the connections and their adjacent portions of associated blades and conductors, I then form molded outer insulating body 25 around body 13. FIhis outer molded body 25 is of one-piece construction and provides additional insulation for my premolded assembly while at the same time enhancing the flexibility of the process for manufacturing a connector plug. Body 25 may be of polyvinyl chloride material, polystyrene, or any other suitable plastic material. In addition, this outer insulating body 25 may be either a soft, supple material, thereby providing a surface which is readily grippable and pleasant to the touch, or it may be a hard and brittle type of plastic material, thus facilitating a very secure plug structure. Furthermore, this outer molded body may consist of a colored plastic substance which provides an attractive appearance to the eye. A luminous substance could also be used for this outer body.

Body 25 surrounds the inner body 13 and is interlocked therewith. More particularly, bridge portion 27 of outer body 25 extends transversally through aperture 16 of the premolded body 13 to provide a secure interlocking relationship between the mated insulating bodies. Rib or bump 29 of the outer body extends inwardly to engage shallow recess 21 of the inner body 13, and thus provides an additional interlocking relationship between the bodies. The interlocking or interdigitating cooperation between the two molded insulating bodies 13 and 25 thus provides a sturdy integrated housing for my connector plug.

It will be apparent that the formation of a subsequent or outer molded insulating body Z5 around the premolded body 13 eliminates any possibility of electrically energized loose conductor strands being present in the area adjacent the outer surface of my improved eletcrical connector plug. Any loosened conductor strands or disarranged conductors are eiiectively contained by the formation of the molded inner body, and outer body 25 eiciently insulates them. In addition, by forming the aperture 16 in the premolded body 13 between connections 6 and their associated bared conductor ends, and then finally molding body 25 with bridge 27 extending through aperture 16, a physical wall of insulating material is formed, to eliminate any possibility of short circuiting Within the plug.

By forming my improved electrical connector plug 15 by a two-step or double-shot molding operation, numerous significant 4advantages have thus been achieved. A relatively low cost insulating material, such as polystyrene, may be used for the premolded body, since this body is covered by the finally molded body 25. In addition, any combination of relatively soft and relatively hard molding compounds, or relatively expensive and relatively inexpensive molding compounds may be utilized for the respective premolded and subsequently molded bodies 13 and 25. If the application calls for it, for instance, a very thin layer of more expensive colored insulating material may be used for the outer insulating body 25, thus economizing on the overall cost of plug insulating material. It will also be understood that the two-step molding process lends itself to the production of more rigidly held contact blades. In addition, the fact that two individual molding operations are involved makes each individual molding step easier than the use of one molding operation, as prescribed by the prior art. For instance, in using a machine which is designed to carry the contacts from a loading station to a first molding station, then to a second molding station, and then to an ejection station, it is possible to obtain a very high output per hour. The reason for this high output is because the first and second individual molding steps are now easier `and quicker than the single large molding step which .was formerly used.

FIGS. 6-8 illustrate va modified form of my invention wherein angle-type connector plug 30 is manufactured by my double-shot molding process. Plug 30 has two contact blades 32 which are functionally similar to blades 1 of plug 15. (See FIG. 8.) As best seen in FIG. 7, blades 32 are crimped to the bared ends 34 ofthe outermost conductors 36 of a three-conductor rip cord 40, to form connections 38. The conductors of the rip cord 40 are, of course, disposed perpendicularly with respect to blades 32, to provide the angular plug configuration. Interposed between conductors 36 is a central grounding conductor 42, which is connected to a cylindrical hollow grounding contact 44 at connection 46, by crimping the hollow contact thereupon. (See FIG. 6.) This grounding contact could also, of course, be solid in construction and may also be soldered or welded to the "rounding conductor. To incor-porate the same salient advantages in angle plug 30 as have been achieved in my aforementioned plug 15, two molded insulating bodies have been interlocked together to form an integrated housing having improved insulating qualities. More particularly, premolded inner body 48 is first molded around connections 38 and 46 and the area adjacent thereto. (See FIG. 7.) Body 4S thus contains any loose strands or `disarranged conductors within itself. Slot 50 is formed in inner body 4S between connections 38. As best seen in FIG. 7, the length of this slot Ialso provides a gap between each bared conductor 34 and the bared end of conductor 42.. Slot 50 thus serves to provide the advantages of preventing any short circuiting between the strands or `disarranged portions of the adjacent bared conductor ends and of also providing an interlocking relationship between body 48 and outer insulating body 52.

After inner body 48 has been premolded around the connections and bared conductors of my angle plug, outer insulating body 52 is molded around body 48. Outer body 52 surrounds inner body 48 `and is interlocked therewith by cooperation with slot 50 to efliciently eliminate the problem of the emergence of electrically energized loose strands in the area adjacent the surface of the molded insulating body. In addition, by means of slot S of premolded body 48, plug 30 also provides protection against short circuiting within the plug. Accordingly, all of the aforementioned functional advantages of connector plug have thus been efficiently incorporated in angular connector plug 30.

While I have illustrated the molded outer body as completely encompassing the molded inner body, it will be lapparent in some instances that .a molded oute-r body may be formed which only partially surrounds the inner body and at the same time provides all of the beneficial aspects of my invention. For example, in the molded angle plug the face ofthe inner body through which the contacts extend could be left uncovered .by insulating material of the outer body.

It will therefore be seen that my new 'and improved wiring device and the method for manufacturing it, as herein illustrated for an electrical connector plug, provide an efiicient and advantageous means Ifor economically eliminating the problem of the emergence of electrically energized loose strands or bared conductors in the area adjacent the surface of a molded insulating body. In addition, my invention afiords reliable protection against short circuiting within the plug. This construction may be efficiently utilized for obtaining very rigidly held plug blades. Furthermore, overall -fiexibility in the selection of finished molding materials is clearly afforded by use of the two-shot molding process.

While in accordance with the patent statutes I have described what at present are considered to be the preferred embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein Without departing from my invention, and I, therefore, aim in the following claims to cover all such equivalent variations Ias fall within the true spirit and scope of this invention.

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

l. A molded wiring device comprising a plur-ality of spaced contacts, an electrical cord having a plurality of conductors mechanically and electrically connected to said contacts to form a plurality of spaced connections, a first body of molded insulating material surrounding said connections, and a second body of molded insulating material surrounding said first body and having a section interposed between said connections thereby to further insulate said connections and strengthen said device.

2. A molded electrical connector comprising a plurality of spaced contacts, an electrical cord having a plurality of conductors mechanically and electrically connected to said contacts to form a plurality of spaced connections, a first body of molded insulating material surrounding said connections, at least one aperture formed in said first body between said spaced connections, and a second body of molded insulating material surrounding said first body .and extending through said aperture to further insulate said connections and strengthen said device.

3. A molded electrical connector plug comprising a plurality of spaced contact blades, each of said blades including a cont-act portion and a terminal portion, a conductor mechanically and electrically connected to the terminal portion of each of said blades to form a plurality of spaced connections, a first body of molded insulating material surrounding e-ach of said connections and any bared conductor adjacent thereto, at least one aperture formed in said first body between said spaced connections and any bared conductor portions associated therewith, and a second body of molded insulating material surrounding said iirst body and extending through said aperture to further insulate said connections and strengthen said plug, said contact portions of said contact blades extending outwardly from said first and second bodies for mating with a suitable female connector.

4. A molded electrical connector plug comprising a plurality of spaced contact blades, each of said members including a contact portion and a terminal portion, a stranded conductor mechanically and electrically connected to the terminal portion of each of said members to form a plurality of spaced connections, la first body of molded insulating material surrounding said spaced connections and any bared conductor adjacent thereto, said first body having a front wall through which said blade members extend outwardly and a rear wall through which said conductors extend outwardly, an aperture formed in said first body between said spaced connections and any bared conductors associated therewith, said aperture being in the configuration of an isosceles triangle the base of which is spaced slightly from and generally -parallel to the front wall of said first body, the portion of said first body between said aperture base and said front Wall serving as a strengthening rib for said first body, and a second body of molded insulating material and one-piece construction surrounding said first body and extending through said aperture to further insulate said connection and strengthen said plug.

5. A molded electrical connector plug comprising a pair of spaced blade members, each of said members including a contact portion and a terminal portion, a stranded conductor mechanically and electrically connected to the terminal portion of each of said members to form a plurality of spaced connections, a first premolded body of insulating material surrounding said spaced connections and any bared conductor adjacent thereto, said first body having a front -wall through which said blade members extend outwardly and a -rear wall through which said conductors extend outwardly, an aperture formed in said first body between said spaced connections and any bared conductors associated therewith, said aperture being in the configuration of an isosceles triangle the base of which is spaced slightly from and generally parallel to the front wall of said first body, the portion of said rst body between said aperture base and said front wall serving as a strengthening rib for said first body, and a second subsequently molded body of onepiece of insulating material surrounding said first body and extending through said aperture to further insulate said connections and strengthen said plug.

6. The plug of claim 5 wherein the insulating material of one of said molded bodies is relatively soft and the insulating material of the other of said molded bodies is relatively hard.

7. A molded wiring device comprising a plurality of spaced contacts, an electrical cord having a plurality of conductors mechanically and electrically connected to said contacts to form a plurality of spaced connections, a first body of molded insulating material surrounding References Cited in the le of this patent UNITED STATES PATENTS Gardner Dec. 12, 1939 Indisch etal Feb. 11, 1941 8 Gits et al. June 9, Benander Jan. l2, Webber July 10, Miller et al. May 27, Schaeffer July 20, Dofsen et al Mar.` 6, Danielson et al. Aug. 26, Gilbert -Tan. 25, Stevens Apr. 17, Bridge et al Feb. 17, Pifer Dec. 1,

FOREIGN PATENTS France Apr. 2, France May 28, Germany Sept. 15,

Claims (1)

1. A MOLDED WIRING DEVICE COMPRISING A PLURALITY OF SPACED CONTACTS, AN ELECTRICAL CORD HAVING A PLURALITY OF CONDUCTORS MECHANICALLY AND ELECTRICALLY CONNECTED TO SAID CONTACTS TO FORM A PLURALITY OF SPACED CONNECTIONS, A FIRST BODY OF MOLDED INSULATING MATERIAL SURROUNDING SAID CONNECTIONS, AND A SECOND BODY OF MOLDED INSULATING MATERIAL SURROUNDING SAID FIRST BODY AND HAVING A SECTION INTERPOSED BETWEEN SAID CONNECTIONS THEREBY TO FURTHER INSULATE SAID CONNECTIONS AND STRENGTHEN SAID DEVICE.

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