US2382292A - Tool for making electrical connections - Google Patents

Description

1945- v. E. CARLSON TOOL FOR MAKING ELECTRICAL CONNECTIONS Filed June 29, 1943 9 "1 ATTRNEY Patented Aug. 14, 1945 TOOL FOR MAKING ELECTRICAL CONNECTIONS Vernon E. Carlson, Cranford, N. J., assignor to Aircraft-Marine Products,

Inc., Elizabeth,

W. 1.. a corporation of New Jersey Application June 29, 1943, Serial No. 492,695

4 Claims. (01. 140-113) This invention relates to means for making electrical and mechanical connections and more particularly to a tool of the pliers type provided with a plurality of die surfaces of graduated sizes for use in crimping a variety of sizes of ferrules,

especially for application of electrical connectors onto appropriate electrical conductors.

In recent years electrical connectors of the solderless type have enjoyed outstanding success. Most such connectors consist of a terminal contact portion to engage the electric terminal or binding post and a sleeve-like ferrule portion for receiving the end of an electrical conductor. In use, the ferrule of the connector is telesooped over the end of the wire of a conductor, and a superior bond is effected between the connector and the conductor by appropriately crimping the ferrule portion of the connector directly onto the wire of the conductor. The connection thus formed not only may be made to meet full strength requirements but also, by virtue of the intimate pressure contact between the surfaces. can be made to have less electrical resistance than any practical connection heretofore known. Various apparatus for crimping connectors onto conductors have been devised, among the more satisfactory being tools of the types described and claimed in the copending applications of U.

A. Whitaker and Vernon E. Carlson, Serial Nos.

455,039 and 455,033, respectively, filed August 17, i

1942; and of Stephen N. Buchanan, Serial No. 474,935, filed February 6, 1943.

It is an object of the present invention to provide a practical tool for forming crimped connections between electrical connectors and electrical conductors, whereby an assortment of different sizes of connectors may be secured to appropriate conductors. Other objects will be in part pointed out as the description proceeds and will in part become apparent therefrom.

In the aforementioned application of U. A. Whitaker a satisfactory tool is disclosed and claimed for attaching connectors falling within a rather limited range of sizes to electrical conductors. It has been discovered that a plurality 'of dies of the general type illustrated in'his application may be combined in a single tool having a correspondingly greater range of applications if the complementary dies are arranged as hereinafter set forth and if special precautions are taken to prevent the ferrules of the connectors from being squeezed or cammed laterallyout of the bite of the proper dies as the jaws are closed.

Notwithstanding that the laws open wider at their outer ends, so that it has beennatural to arrange the largest holes at this end, I use the reverse arrangement, and thereby obtain the greatest mechanical advantage close to the pivot axis for the jaws. The smaller dies are arranged. correspondingly further from the pivot axis; and thus with a normal hand pressure applied to the tool a proper crimping force is applied to whichever ferrule is engaged in its appropriate dieopening. This concept, however, is not a wholly satisfactory solution of the problem. In order to use this reversed arrangement so as to crimp the largest ferrules between dies located closest to the pivot axis of the jaws, it is necessary that the jaws be opened to an abnormally wide angle in order to separate the die surfaces sufilciently to insert the ferrule, and unless special precau tions are taken, the ferrule is not properly engaged upon closing of the laws, but instead is squeezed or cammed out of the die, so as to escape entirely from the ,bite of the dies or'at best to produce an objectionably lop-sided crimp.

The present invention includes the discovery that flat, relatively narrow die areas placed on each side of the concave dies which do the main part of the crimping may advantageously be used to bite into the ferrule and to prevent it from being displaced laterally with respect to the pivot point about which the jawsclose. These flat dies flank, and intersect with, the concave dies to form a sharp edge between each concave surface and each fiat surface. It has. been discovered that between these sharp edges and flat flanking tion even though the operation is carried out quite near the pivot point about which the jaws close, and by keeping the flanking surfaces narrow, the coining areas of the dies are reduced and hence less crimping pressure is required.

In this specification and the accompanying drawing, I have shown and described a preferred embodiment of my invention; but it is to be understood that this is not intended to be exhaustive nor limiting of the invention, but on the contrary is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the-manner of applying it in practical use so that they may modify and adapt it'in various forms, each as may be best suited to the conditions of a particular use.

In the accompanying drawing, in which an exemplary embodiment of the invention for J including a plurality of progressively sized dies, formed in accordance with the invention;

Figure 2 is a sectional view through the jaws of the hand tool illustrated in Figure 1, butshow ing the jaws closed upon and crimping together an electrical connector and conductor; and Figure 3 is a perspective view of the electrical connector and conductor as crimped together in Figure 2.

With reference to Figure l, a tool is shown consisting of a pair of hand levers 20 and 2| pinned together by a pin 24 and pinned respectively to an, upper jaw member 26 and a lower jaw member '21, by an upper jaw pin 28 and a lower jaw pin 29. Jaws 26 and 21 are linked together with a link 30 by means of an upper link pin 32 and lower link pin 33. Between the jaw members a, bearing pivot pin 34 is positioned. -Hence, when levers 20 and 2| are brought toward one another, jaw pins 28 and 29, being located on the other side of pin 24 from the hand portions of levers 20 and 2|, are separated, and jaw members 26 and 21 are rotated about link pins 32 and 33 with a rocking motion upon pivot pin 34 to close the free ends of the jaw members with a greatly multiplied force.

Jaw member 26 is provided with three concave die surfaces 40, 42 and 44, and jaw member 21 is correspondingly provided with three cooperating concave die surfaces 4|, 43 and 45', respectively. Die surfaces 40 and 4| are larger than die surfaces 42 and 43, and die surfaces 42 and 43 are larger than die surfaces 44 and 45. Jaw member 25 is also provided with flat, relatively narrow die surfaces 50, 52, 54 and 56 which flank the various concave die surfaces 40, 42 and 44. correspondingly, lower jaw member 21 is provided with fiat, relatively narrow die surfaces 53, 55 and 51 flanking the lower concave die surfaces 4|, 43 and 45; The free ends of the jaws are provided with stops 50 and 5| to limit the extent to which the jaw members may be closed.

As shown in Figure 1, each side of the jaw portions of members 26 and 21 is beveled from adjacent pivot pin 34 to the free ends thereof, and these bevels increase in extent from the pivot pin toward the free ends of the jaws. Thus, fiat die surfaces 50 and 5| are broader, in a direction across the face of the jaws, than surfaces 56 and 51. And the intermediate die surfaces likewise vary in breadth accordingly, from broader toward pivot pin 34 to narrower toward stops 60 and 6|. Hence, the bevel configurations of the tool combine with the depth of the die I surfaces to give broader die surfaces where the larger ferrules are to be crimped and narrower die surfaces where the smaller ferrules are to be crimped. In this manner the proportions of each die and of each resulting crimp are maintained at an optimum for every ferrule, and at the same time the mechanical advantage varies so as to give the greater force required for the larger crimping areas and heavier ferrules, all by a simple series of dies of different sizes feasibly combined in a single, multirange-tool.

Figure 2 shows jaws 26 and 21 closed upon an electrical conductor having a bared wire end 1| positioned in an electrical connector consisting of a terminal contact portion 12 and a ferrule portion 13. The cooperating die surfaces 42 and 43 are shown impressing a double crimp into ferrule 13 of the connector. This double crimp is further described in the above-mentioned application of U. A. Whitaker. When ferrule 13 is positioned, for example, between die surfaces 42 and 43 and the dies are closed together, however, the sharp edges above (see Figure 1) between die surfaces 52 and 42, and 42 and 54, and below between die surfaces 53 and 43, and 43 and 55, along with the flanking, fiat die surfaces, serve to engage and support the ferrule; and in the finished crimped connector, as illustrated in Figure 3, narrow fiat crimped areas 15 are formed by fiat die surfaces 54, and convex'crimped areas 14 are formed by concave die surfaces 42.

The particular pair of main concave die surfaces to be used in a given crimping operation is selected in accordance with the size of the ferrule to be crimped, and ordinarily the preferred relationship consists of selecting concave dies having a chordal width approximately equal to the inner diameter of the particular ferrule, as described and claimed more fully in said copending application of Stephen N. Buchanan, Serial No. 474,935, filed February 6, 1943.

The invention has been described in connection with one type of hand tool. Obviously other types might equally well incorporate the invention. And it might be incorporated in a pedaloperated or power-operated die press. The discovery is a thoroughly practical one and may be applied wherever a series of sizes of die surfaces are desired in a multisize tool. Moreover, certain features of my invention may be used wherever two dies approach one another angularly, as about a pivot axis, and in general wherever there is a tendency for the work between the dies to move outwardly from the pivot point as the jaws close.

As various embodiments may be made of the above invention and as changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in "alimiting sense.

I claim: a

1. In apparatus of the character described and including a pair of dies closable toward one another, a series of concave crimping surfaces in each die; each die being beveled in the direction I toward the face of the die that engages the work,

said concave crimping surfaces being cut into the beveled faces of the dies and ranging through a progression of sizes and depths, and said beveling being progressively greater toward the ends of the dies where the concave crimping surfaces are smallest and shallowest.

2. The invention of claim 1 wherein adjacent concave crimping surfaces are separated by narrow flat die surfaces.

3. A tool adapted to crimp a plurality of sizes of electrical connectors onto electrical conductors and including, a pairof jaws closable toward one another in pliers fashion about a pivot point, and multiple die surfaces in the jaws extending in each from a point adjacent the pivot point to a point adjacent the free end of each jaw; said multiple die surfaces including a series of concave ferrule-crimping surfaces ranging in sizes progressively with the largest located nearest the pivot point and the. smallest located nearest the free ends of the jaws, whereby the greatest force multiplication is available for the largest'ferrules crimped; said die surfaces for crimping a given ferrule including opposing concave die portions in the upper and lower jaws of a width approximately equal to the inner diameter of the ferrule to be crimped, and narrow float dies portions I aaaaaee v multiple die surfaces including a series of con cave ferrule-crimping surfaces ranging in sizes progressively with the largest located nearest the flanking each side of the concave portions, whereby, as the jaws close upon the ferrule, the die edges formed by the intersections of the concave portions withthe flat portions tend to dig into and hold the ferrule and the narrow flanking flat portions engage and fold diametrically located edges of the ferrule being crimped to reduce the tendency of the ferrule toward lateral displacement or spreading as the concave die portions crimp the central areas of the ferrule into the electrical conductor.

4. A tool adapted to crimp a plurality of sizes of electrical connectors onto electrical conductors and including, a pair of jaws closable toward one another in pliers fashion about a pivot point, and multiple die surfaces in the jaws extending in each from a point adjacent the pivot point to a point adjacent the free end of each jaw; said pivot point and the smallest located nearest the free ends of the jaws. whereby the greatest force multiplication is available for the largest ferrules crimped; the die-carrying portions of the jaw members being beveled in the direction in which each jaw closes, whereby the deeper cut die ouriaces are correspondingly broader than the ahallower die surfaces. and the bevel of each jaw being progressively deeper in a direction from the pivot point toward the free end of the jaw. whereby the die surfaces toward-the free ends of each jaw are correspondingly narrower than the die VERNON E. canteen.

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