US2825750A - Connector with spring insert having a small distended portion at its inner end and method of assembling same - Google Patents

Description

March 4, 1958 F A STOCKWELL 2,825,750 CONNECTOR WITH SPRING INSERT HAVING A SMALL DISTENDED PORTION AT ITS INNER END AND METHOD OF ASSEMBLING SAME Filed March 10, 1954 9L V a 1 14 21 j V 12 I 1a 3 g 30 V llllllllll 3 12 \M 20 a4 15 14 21 j 4 2 1 III United States Patent f CONNECTOR .WITH SPRING' INSERT HAVING A SMALL DISTENDED PORTION AT ITS INNER END AND METHOD OF ASSEMBLING' SAME Francis A. Stockwell, Bryan, 0hio,.,assignor to-ldeal Industries, lnc., Sycamore, 111., a corporation of Delaware Application March 10, 1954, Serial No. 415,349

8 Claims. (Cl. 174-87) My invention resides in the field of connectors, specifically electrical connectors, and is an improvement on prior connectors used to join the stripped ends of two or more electrical leads or conductors. This type of connector generally has a cap or cover element made of aninsulating materialwith a coil spring insert posi tioned inits centrally disposed bore. The cap of the connector is. generally conical as is its centrally disposed bore and open generally at only one end although at least-V theoretically it could be; openat both ends. I have statedthat the material of the capis generallyinsulation, and it could be any ofthe well-known insulating materials, such as any of the plastics, a Bakelite, nylon, etch At least a portion of the inner surface, of tl1 e bore is threaded and receives the coil spring insert which is also generally conicalin configuration to conform generally. to the conical bore. Prior to insertion in the connector, the. stripped ends of the wires may be twisted together, if desired, although this is not necessary, and the open end of the bore may be slightly flared to guide the stripped ends and thus aid their insertion.

The coil spring wire is made of a generally harder metal than the electric wires so that the turns of the coil will biteinto, the surface of the wires and-form slight lands and groove on them. This can be termed a threading action and it effects a definite locking efiect and generally prevents any unauthorized withdrawal of the wires- This connector has performed satisfactorily in the past. However, its users have experienced the disadvantage of the stripped ends of the wires coming out of the connector after an extended period of use when the connectoris subjected to vibration, excessive tension and other similar conditions.

Therefore, a primary object of my invention is a new and improved connector in which the strippcd ends of the electrical Wires will not come out of the cap after extensive use, whenthe connector and. its; wires are subjected to tension or to vibration, or-the like.

Anotherobject is a connector of the above type constructed and adapted to firmly lockthe stripped ends of the Wires by an improved locking action in a new and novel manner.

Another object is a new and improved method of forming or making a connector of the above type.

Other objects will appear from time to time in the ensuing specification and drawings in which:

Figure 1 is a longitudinal sectional view of a connector cap with its coil spring insert diagrammaticall positioned above it prior to insertion;

Figure 2 is a view similar to Figure 1 but showing the spring disposed in the bore of the cap;

Figure 3 is a view similar to Figures 1 and 2 illustrating the drive mechanism in operation for fully seating the spring;

Figure 4 is a view similar to the previous figures but showing the coil spring fully seated in the cap; and

2,825,750 Patented Mar. 4, 1958 Figure 5 is an enlarged view of a part of Figure 4 showing a locking section of the connector.

In Figure 1, the connector is indicated generally at 10 and has a shell or cap 12 with a centrally disposed bore 14 open at one end as at 16 and closed by a wall portion 18 at the other end. The cap andjboreare conically shaped, and the inner surface of the bore is threaded through at least a portion of its length as at 20. The other portion 21 can have a generally smooth surface and be flared out slightly to facilitate insertion ofv the wires or leads.

During the process of manufacture, a coil spring 22 is, inserted in the cap and is turned, while'engagingthe threaded surface 20, until it is fully seated. The spring, as'shown in Figure l, is also tapered or conical andis adapted generally to fit the threaded portion, 20 ofthe bore.

The bore 14 has an angle of divergence indicated generally at 24, which is slightly less than the angle of divergence 26 of the spring. Thus, when the spring is. dropped or placed in the cap, as shown in Figure 2, only the top or large end 28 will contact the threaded bore while the small end 30 will be spaced slightly, as shown at 32. Thus, theoretically, only the first'turn at the large end 28 will contact the threads while the .lower tapered portion will be spaced away from the threaded bore- The space 32 at the small end of the spring should be the greatest and the spacing should decrease progressively upward until the point of contact at, the large end 28.

To fully seat the spring in the threaded bore, a drive member or element 34 is inserted and forced downwardly into the bore to engage the spring. The drive member has a tapered end portion 36 which is composed of a plurality of flat sides; for example, three or more, which intersect each other to provide relatively sharp, defined edges 33. Upon engagement with the spring when the drive member is forced down into the spring and cap, the edges Will bite into the turns of the spring slightly and will grip the engaged portion so that, upon rotation of the drive element, the spring will rotate with it. It should be noted that the drive element and its tapered end portion are of such a size relative to the cap and spring that the tapered end portion will engage the spring well down toward the small end 30.

The drive element is rotated clockwise as viewed from above. This tends to wind up the spring and at the same time fullyseats it in the bore. At the same time,the drive member is thrust downwardly so that the spring will be slightly distended in at least one place, as shown in Figure 5, and the turns of the spring, due to this distending action, will skip at least one of the threads, possibly more. In Figure 5, I have shown the adjacent turns 40 and-42 as being spaced apart one thread so that a gap 44 is presented to the wires during their insertion.

Thus, the smooth interior threadlike surface .of the coil spring insert, when it is fully seated in the threaded portion of the bore, will be broken or separated in one or more places.

The use, operation and function of my invention are as follows:

A connector of this type is designed to squeeze together a plurality of metal wires at the same time that it threads them. As the connector is turned down over the wires, the turns of the coil spring insert will groove or indent the metal of the wires and threads will be formed on them.

It is desirable to effect an improved locking action between the coil spring and the metal wires. To do this, I have interrupted or broken the spacing or pitch of the wires so that at least at one point the pitch of the grooves on the metal wires will be broken.

When the stripped ends of the wires are forced into the bore, they will be grooved or threaded upon engagement with the coil and a tight fit will be efiected. The pitch of thethreads formed on the surface of the stripped ends will be the same as the pitch of the coil spring insert. As the cap is turned down on the wires, the stripped ends will move into the bore and the threads or grooves formed on the stripped ends will be interrupted upon engagement with the spaced portion or distended area 34. The pitch of the threads formed on the stripped ends will be broken and an irregular threading will be set up. Thus, the metal of the stripped ends will flow into the area 4 3 between the two turns 40 and 42 in Figure 5, and a tight locking action will be acquired. In subsequent use when subjected to excessive vibrations, tension, or various types of wear, the locking action substantially increases the holding action of the connectors.

It should be understood that the spacing in the coil spring insert due to the skipping of one or more of the threads can be efiected at any point by proper manipulation of the driver. The space or skip occurs generally adjacent the tapered contact portion 35, so that if the driver is larger in diameter the tapered portion will contact the spring insert closer to its large end 28, and the space in the spring would occur farther up in the bore in Figure 4.

With the angle of divergence of the coil spring being greater than the angle of divergence of the threaded portion of the bore, only the top of the spring will contact the cap when the two are nested as in Figure 2. The driver element contacts the inner surface of the spring and initially turns it slightly until the top 2% is fully seated. At this point, the rotation will slow down or cease in the top portion and the bottom portion 38 will continue to rotate. This tends to coil or tightly wind the spring and at the same time the driver element is forced downwardly into the bore. Thus, the spring is distended and at one or more places, it will skip a thread as in Figure 4.

It is also desirable that the diameter of the wire used for the coil spring be of such a size as to properly fit in the V-shaped threads in the bore as shown in Figure 5. If the threads have a greater pitch than the diameter of the wire, the coil spring will be distended when it is turned down in the cap. If the pitch of the threads is too small,

the coil spring will not be firmly gripped in the threads.

While I have shown and described the preferred form of my invention, it should be understood that numerous modifications, changes, alterations, and substitutions can be made without departing from the inventions essential theme, and I desire that my invention be unrestricted except as by the appended claims.

I claim:

1. In a joining and insulating connector device for covering and joining the stripped ends of insulated electric conductors, comprising an insulating cap body having a bore centrally disposed therein of a generally conical configuration, the cap body having a wall portion closing the small end of the bore with the large end being generally open to provide for the introduction of the stripped ends of the conductors, at least a portion of the surface of the centrally disposed bore being generally conical and having threads formed thereon, and a tapered coil spring insert having a large and small end positioned in the centrally disposed bore and engaging the surface, the turns of the coil meshing evenly with the threads except in at least one place where the coil is distended and at least one thread is skipped.

2. The structure of claim 1 wherein the normal angle of divergence of the coil spring insert is greater than the angle of divergence of the threaded portion of the bore prior to assembly.

3. The structure of claim 1 wherein the skipped thread occurs adjacent the small end of the coil spring insert.

4. A method of making an insulating connector having an insulating cap body with a centrally disposed bore open at one end and a coil spring insert positioned in it, the normal angle of divergence of the coil spring insert being greater than the angle of divergence of the bore, comprising the steps of positioning the spring insert in the threaded bore with the top of the spring being the only portion that engages the bore, rotating the spring in the direction tending to wind it and at the same time applying a thrust force against the spring adjacent its small end, and fully and firmly seating the spring in the threads of the bore by turning it downwardly into the bore and thereby causing the spring to distend in at least one place by having one turn of the coil skip a thread in the bore.

5. The structure of claim 1 further characterized in that the conical configuration of the bore extends the full length of the bore from the open large end to the wall portion closing the small end, the threads formed in the bore extending from the open large end over at least a substantial portion of the bore toward the wall portion closing the small end.

6. The method of claim 4 in which the thrust and rotative forces are applied at the same point.

7. A method of making an insulating connector including the steps of providing an insulating cap body with a centrally disposed threaded conical bore open at one end, positioning a generally conical coil spring insert in the bore, with the normal angle of divergence of the coil spring insert slightly greater than the angle of divergence of the bore, rotating the spring insert in a direction tending to wind it and reduce its diameter, and at the same time, applying a thrust force against the spring insert adjacent its small end, and fully and firmly seating the spring insert in the threads of the bore by turning it downwardly into the bore and thereby causing the spring insert to distend in at least one place adjacent the point of application of the thrust force by having one turn of the coil skip a thread in the bore.

8. The method of claim 7 in which the thrust and rotative forces are applied at the same point.

References Cited in the file of this patent UNITED STATES PATENTS 197,467 Harvey Nov. 27, 1877 1,230,503 Richmond June 19, 1917 FOREIGN PATENTS 445,679 Great Britain Apr. 16, 1936

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