US2648050A - Electrical connector having insulating piercing barbs - Google Patents

Description

Aug. 4, 1953 Q. BERG t 2,648,050

ELECTRICAL CONNECTOR HAVING INSULATING PIERCING BARBS Filed Feb. 4, 1950 2 Sheets-Sheet 1- TJEE.

I 6A INVENTOR.

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Aug. 4, 1953 Q. BERG 2,648,050

ELECTRICAL CONNECTOR HAVING INSULATING PIERGING BARBS Filed Feb. 4, 195

2 Sh eets-Sheet 2 TJqlU.

swim *JW ATTORNEYS.

futNT/N 195m Patented Aug. 4, 1953 ELECTRICAL CONNECTOR HAVING INSULATING PIERCING BARBS Quentin Berg, New Cumberland, Pa.

ApplicationiFebruary 4, 1950,Serial No. 142,511

6 Claims.

This invention relates to solderless-type insulation-piercing connectors and terminals for use in making electrical connections, and particularly to the shape'and arrangement of the insulationpiercing prongs of such connectors.

' Connectors of'this type usually are provided with a ferrule portion, which surrounds andgrips the insulation of an electrical conductor, and

with barbs or prongs which pierce the insulation and makecontact with the conductive core. Such connectors elimina'te the necessity for stripping the insulation from the core and soldering the connector or terminal thereto. The increased production speed andeconomy resulting from the use of such connectorsmakes it desirable to use them for as many applications .as possible.

The-present invention is directed to increasing the pull-out strength of such connectors, that is, thetensile force required to separate the connector from the conductor, and improving the electrical contact between the connector and the conductive core of the insulated wire to which it'is-secured, thus increasing the number of applications for which the connectors can be used successfully.

The ferrule-forming portion of the connector is-usually trough-like inshape with the insulation-piercing prongs extending upwardlyfrom the bottom. The prongscanbe formed by making a V-shaped cut in the ferrule-forming portion .and bending the metal defined by the cut inwardly. In-the connectors in use prior to the present invention, the prongs usually are bent to form anangleapproximately normal to a plane tangent to the bottom of the ferrule trough, that is, the prongs-are bent upwardly until they point in a direction approximately parallel to the direction of movement of the wire as it is moved downwardly inthe trough to force the prongs through the insulation. Thus, in the usual construction, the pointed tip of the prong is directly over the open space in the ferrule formed by removal of the prong material. In such connectors, I the prong does not always pierce the insulation properly and in nearly all cases when the connector is assembled by crimping, the prong will be canted toward the opening left in the ferrule by its formation. This is caused in part because the prong is unsupported by the ferrule in line with the direction of the force exerted on the tip of the prong as the insulation is pressed downwardly on it, so that a torque is created which tends to bend the prong back toward the pening in the ferrule from'which the prong was lanced. This bending movement of the prong may cause its point to slide across the surface of the insulation of the wire, or itmay be :accompanied by a sidewise movement of the wire within the ferrule. In either event, the resulting electrical connection is not satisfactoryand occasionally: the prongs fail completely to make i contact with the electrical conductor.

In'accordance with the present" invention, the

' prong is bent upwardly from the ferrule-forming portion and slightly beyond the normal, for example, so that the point of the prong is directly above the line where the prong joins, that is, is

supported by, the ferrule. This arrangement prevents the prong from being canted toward the prong opening in the ferrule when the insulation is pressed down on the prong, thus insuring that the insulation will be :piercedand agood electrical contact'made with the conductive core, and

providing a firmer zgrip by the connector on the electrical conductor thus increasing the pullout strength. I H

In a .preferredembodiment-of the invention, the desired position and shape of the prong is obtained by upsetting the prong by a suitable force or impact appliedto the face of the prong which not only causes a tapering in the thickness of the prong, but alsotends to movethe prong bodily away from the V-shaped cutso that the body of the prong is positioned above an area of the base of the ferrule-forming portion that is substantially outside the area defined by the V- shaped cut in the base.

I A good electrical connection is further insured and the pull-out strength is further increased by a second prong spaced longitudinally along the ferrule from the-first, but canted in the opposite direction so that the tips of the two prongs 1ie=on opposite sides of a center line extending parallel with the longitudinal axis .of

the ferrule. This-staggered arrangement of the prongs tends :to prevent any tendency of the wire to move sidewiseas it ispressed downwardly ont the prongs, and thereby toinhibit further any'tendency of the prongs to bend back toward I prongis positioned at anangle with respect to the longitudinal axis of the connector so-that the wide dimension of the prong isparallel tothe direction of the twisted strands of the wire core. This permits the prong to enter more easilybetween the strands of, wire and further reduces the tendency of the prong t bend instead of entering between the wirestrands. Two or'more of these angularly-positioned prongs can be spaced along the ferrule with their wide dimensions in alignment so that both prongs enter between the same strands of wire, or they may be positioned in parallel relationship along the longitudinal axis of the ferrule so that they enter between different strands of the wire core.

The invention will be more clearly understood, and its objects made more apparent, by the following description considered together with the following drawings in which:

Figure 1 is a perspective view of a connectorforming strip;

Figure 2 is a perspective View of a terminal connector formed from the strip shown in Figure 1;

Figure 3 is an enlarged sectional view taken along line 3--3 of Figure 2, showing the relative positions of the two insulation-piercing prongs;

Figure 4 is a plan view of an insulation-piercing prong and a portion of the base of a ferruleforming portion formed in accordance with the present invention;

Figure 5 is a bottom view of the structure shown in Figure 4;

Figure 6 is an enlarged perspective view of the structure shown in Figures 4 and 5;

Figure 7 is a plan view similar to Figure 5 in which the prong is bent upwardly in a manner known to the prior art;

Figure 8 is a bottom view of the structure shown in Figure '7;

Figure 9 is a perspective view of the connector shown in Figure 2 after being assembled with an insulated wire;

Figure 10 is an enlarged sectional view taken along line l0-|0 of Figure 9;

Figure 11 is a plan view of another connector illustrating a second embodiment of the invention;

Figure 12 is a bottom view of the connector shown in Figure 11 after being assembled with an insulated wire;

Figure 13 is an enlarged sectional view taken along line l3l3 of Figure 12;

Figure 14 is a plan view showing still another embodiment of the invention; and

Figure 15 shows the connector of Figure 14 after being assembled with a stranded wire from which the insulation has been removed.

Connectors of this type are usually formed in long strips, as shown in Figure 1, which are fed into automatic assembling machinery, or which are subsequently cut into separate connectors as shown in Figure 2. The connector shown in Figure 2 of the drawings has been formed from the flat strip shown in Figure 1 and is provided with a ferrule-forming portion, generally indicated at 2 and a secondary connector portion, generally indicated at 4, shown in the form of a forked or spade-tongue connector, the entire connector being formed of bendable electrically conductive metal.

The ferrule-forming portion 2 is trough-like in shape and has a base 6 and two pairs of opposed upwardly-extending ears 8 and 12. In the assembly of the connector with an insulated wire I4 (Figures 9 and 10) the wire is placed in the trough of the ferrule-forming portion 2 and as the wire is pressed downwardly, the ears 8 and I2 are bent inwardly and downwardly around the outside of the insulating covering l6 of the wire M. A die of a type suitable for assembling connectors of this type is described in the copending application of James C. Macy,

4 Serial No. 717,842, filed December 23, 1946, now Patent No. 2,600,012, issued June 10, 1952.

In order to make electrical contact with the strands 18 of the conductive core of the wire [4, two insulation- piercing prongs 22 and 23 are provided which extend generally upwardly from the base of the ferrule 2. Except for having been bent upwardly in opposite directions, the two prongs 22 and 23 are identical so that only prong 22 is described in detail. The prong 22 is formed conveniently by lancing from the same metal sheet that forms the ferrule. A V-shaped notch is cut in the base 6 of the ferrule-forming portion and the prong is turned upwardly as shown in Figure 3. The prong 22 is advantageously swaged along its length to form a sharp point 25 at the end of the prong and at the same time to position the prong and lengthen it so that it is somewhat longer than the opening 26 from which it was taken.

If the barb 22 were merely bent sufficiently that its tip 25 were directly over the opening 25, the prong would have difliculty in entering the insulation I6 and would not make the best contact with the strands 18 which form the conductive core of the wire, and the wire-connector assembly would have lower pull-out strength than if the prongs were properly embedded in the wire strands. The prong 22, therefore, is bent slightly beyond the usual position so that the pointed tip of the prong is directly over the point at which the prong joins the base of the ferrule, that is, the tip 25 of the prong 22 is positioned on a line 29 which extends through the junction of the base and the prong or through the base of the ferrule-forming portion 2 at a point opposite the opening 26 from which the prong was stamped, this line being parallel to a center line 30 extending through the transverse center of the base in a direction perpendicular to a plane tangent to the base at that point. Thus, if the ferrule-forming portion 2 is positioned so that the insulated wire l6 moves along a vertical path as it is being assembled with the connector, a vertical line through the tip of the barb 25 will not pass through the opening 26, but will pass through a solid portion of the ferrule base. This shape is achieved conveniently during the swaging operation in which a suitable force is applied to the face of the prong adjacent the opening from which the prong was formed, so that the body of the prong is positioned above a portion of the ferrule base which is not within the area defined by the V- shaped cut in the ferrule base.

The position and shape of the prong 22 will be made clearer by a consideration of Figures 4 to 8. As may be seen in Figures 4 and 5, the V-shaped cut by which the prong 22 was formed extends only to a point 32 approximately at the face of the prong and does not extend to the rear of the prong (the front or face of the prong being the side facing the opening 26). Figure 7 shows a similar prong 22A but which was formed merely by bending the metal from the V-shaped notch 26A upwardly, the cut in the base extending to a point 34 at the rear of the prong 22A. It will be noted in Figure 5 that the point 25 of the prong 22 is directly over a point on the base 6 that is outside the area defined by the V-shaped cut, so that it is solidly supported by the base 6, whereas the portion of the base or prong immediately beneath the point 25A of prong 22A is within the area defined by the 'V-shaped cut so that it is not solidly sup ported by an uncut portion of the base. During the piercing operation, as the wire exerts a force along the longitudinal axis of the prong 25A, the prong has a tendency to be bent back toward the opening 26A in the base BA from which it came. This is in part because of the lever arm, which is equal to the horizontal distance between the tip 25A of the prong and the junction of the prong and the base at point 34, by which a torque is produced on the prong tending to bend it back toward the opening 26A. This effect, coupled with the fact that the metal of the prong does not have theresistance to bending in the direction toward its :original position that it does to continued bending in the opposite direction, accounts for a substantial part -of the trouble encountered with connectors of this type.

' Figure 6 is a bottom view of the prong 22 shown in Figure 5 further illustrating that substantially none of the body of the prong is over the opening 28, whereas in Figure 8, which is a bottom view of the prong 22A and the base BA shown in Figure 7, substantially theentire body of prong 22A is over the area defined by the cut forming the opening 26A.

The end view of Figure 3 shows the positions of the two prongs '22 and 23 with respect to the center line 30 of the ferrule-forming portion 2. The prong 23 is formed by making a V-shaped cut in the base of the ferrule identical with the notch cut to form the prong 22, but with the point of the V directed towards the opposite side of the ferrule-forming portion 2, In each case, the base of the V-cut is near the longitudinal center-line of the base 6 of the ferrule-forming portion, so that when the prongs 22 and 23 are bent upwardly as shown in Figure 3, the tip of each prong is directly above the point at which the prong joins the base 6 and the tips of the prongs are on opposite sides of the center-line 30. When the insulation is pressed downwardly upon the prongs, the prongs tend to maintain the central position of the wire and prevent sidewise motion. Such sidewise motion of the wire is of concern because it is advantageous for the wire to fit relatively loosely between the ferrule ears 8 and I2. This is because the prongs 22 and 23 can penetrate the insulation more readily before it is confined under pressure, that is, the insulation must be able to yield freely while the piercing operation is being performed. Once the insulation is gripped under pressure, it becomes more dense and piercing is more difficult.

Figure 11 shows a U-shaped ferrule-forming portion, generally indicated at 34, formed of malleable electrically conductive metal, which is provided with two prongs 3B and 38 positioned at an angle to the longitudinal axis of the connector, this angle advantageously is approximately equal to the pitch of the twisted outer strands 42 of a conventional insulated wire indicated at 44 in Figure 12. The strands 42 shown in Figure 12 represent only the outer strands of the wire core that are adjacent the prongs 36 and 38. The prongs 36 and 38 aer identical with the prongs 22 and 23 except that they are positioned at an angle to the axis of the connector and their tips are positioned on a line forming the same angle with the connector axis as the strands 42. When the wire 44 and the ferruleforming portion 34 are assembled (Figures 12 and 13) the prongs 36 and 38 piece the insulation and are forced between the same outer wire strands, and the upwardly extending ears of the ferruleforming portion are crimped around the outside I of the insulation of the wire 44; substantially a's of the prongs, they provide a high pull-out strength. The connector 34, in this example, does not have a secondary connector and may be used as a plug or any desired secondary connector can be formed integrally with it or-subsequently secured to it.

The angularly-positioned prongs can of course be placed in other positions, for example, as shown in Figures 14 and 15, two prongs -42 and 44 are positioned at the same angle to the longitudinal axis of a ferrule-forming portion 46 as are the prongs 36 and 38, but the points of-the prongs42 and 44 aresubstantially on the longitudinal axis of the connector so that the prongs will be aligned with thedirection of the outer layer of wire strands 48 (Figure 15) of a wire 52 of standard pitch, but when assembled, will enter between different strands of the wire. In other respects the connector shown in Figures 14 and and 15 is the same as the one shown in Figure 11.

The prongs formed in accordance with the present invention will have increased penetrating and gripping power whether used with insulated wire or with wire from which the insulation has been removed. Figure 15 shows the connector applied directly to the strands 48 of the wire 52, the insulation near the end of the wire having been previously removed. The connector thus binds the strands 48 securely together and makes a firm electrical contact therewith.

Although connectors such as this are primarily intended for use without stripping the insulation from the wire, there may be occasions, for example, with aluminum wire, when it is desirable to use connectors of this type to bind and make connection with the bare wire.

The foregoing examples are given to illustrate the present invention and to teach others how to apply and utilize the invention, but it is to be understood that the scope of the invention is not to be limited to theparticular forms shown and that many other and diiierent embodiments can be made in order to suit the invention to particular uses without exceeding the scope of the invention.

What is claimed is:

1. An electrical connector comprising a ferrule-forming portion and a plurality of insulation-piercing prongs formed integrally with said ferrule-forming portion and extending inwardly thereof, said ferrule-forming portion having an opening adjacent each said prong from which the material forming the respective prong has been bent away, the tip of each prong being positioned directly over a portion of said ferrule be-' yond the end of its adjacent opening, the tips of said prongs being displaced transversely from each other with respect to the longitudinal axis of said ferrule-forming portion.

2. In an electrical connector of the type having a ferrule-forming portion of bendable metal adapted to receive and be crimped to an insulated wire, wherein said ferrule-forming portion is adapted to be assembled with said wire by relative rectilinear movement of said wire and said ferrule-forming portion, the improvement comprising a wire-piercing prong integral with said ferrule-forming portion and extending inwardly thereof, said prong having been at least partially formed by bending inwardly metal within a V- shaped cut in said ferrule-forming portion, said prong being shaped and positioned so that a straight line through the tip of said prong and parallel to the direction of said relative movement passes through a point on said ferrule-forming portion beyond the area defined by said V- shaped cut in the direction of the junction where said prong is connected to said ferrule-forming portion.

3. A connector as claimed in claim 2 wherein said prong is positioned so that the direction of its widest dimension forms an oblique angle with the longitudinal axis of said ferrule-forming portion.

4. A connector as claimed in claim 2 including a second prong substantially identical with said wire-piercing prong, the directions of the widest dimensions of said prongs being parallel and forming an oblique angle with the longitudinal axis of said ferrule-forming portion.

5. A connector as claimed in claim 4 wherein the widest dimensions of said prongs are in a common plane.

6. In an electrical connector, a ferrule-forming portion of bendable metal having a V-shaped cut therein, and a wire-piercing prong extending from the inner surface of said ferrule-forming portion and formed of metal released by said out, said prong having front, rear, and edge surfaces, said edge surfaces being terminated substantially at the inner surface of said ferrule-forming portion.

QUENTIN BERG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,687,574 Liss Oct. 16, 1928 1,989,718 Taylor Feb. 5, 1935 2,279,794 Olson Apr. 14, 1942 2,302,767 Hackbarth Nov. 24, 1942 FOREIGN PATENTS Number Country Date 617,955 France Mar. 1, 1927

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