US3085313A - Method of making an electrical connection - Google Patents

Description

April lfi, 1963 J. c. MACY METHOD OF MAKING AN ELECTRICAL CONNECTION Filed April 9, 1955 2 Sheets-Sheet l 2 g INVENTOR.

ATTORNE 6.

April 16, 1963 J. c. MACY 3, METHOD O MAKING AN ELECTRICAL CONNECTION Filed April e, 1955 2 Sheets-Sheet 2 INVENTOR'. (fl/145$ C Mar ATTORNEYS.'

3,085,313 METHQD IF MAKING AN ELECTRICAL CONNECTION James C. Macy, Westfield, N.J., assignor to AMP Incorporated, a corporation of New Jersey Filed Apr. 9, 1953, Ser. No. 347,806 1 Claim. (Cl. 29-15555) This invention relates to the crimping of electrical terminals, or the like, into interlocking and good electrically conductive relation to electrical conductors. A general object of the invention is to provide an improved method of effecting such connection of ferrules and conductors. This application is a continuation-in-part of my copending application Serial No. 580,841 filed March 3, 1945, now Patent No. 2,639,754.

To insure good electrically conductive forged connection between a conductor and a terminal attached thereto, it is important when crimping the ferrule onto the conductor, that opposed clean metal surfaces of said parts be pressed into intimate contact and that a permanent set of said parts in the pressure contact relation to each other he obtained.

Also, to afford optimum strength of the connection, or suitable resistance to breaking or yielding under longitudinally applied strain, the crimping should effect a permanent distortion of the parts by which the conductor is interlocked with the ferrule. These effects are obtained by applying die pressure in accordance with the present invention to the ferrule and that portion of the conductor which is encircled thereby.

Heretofore, crimping of terminal ferrules and electrical conductors into electrically conductive and interlocking relation to each other has commonly involved the use of directly opposed crimping dies. The pressures applied through such dies upon opposite sides of the ferrule, being directly opposed, cause lateral and longitudinal extrusion or cold flow of the metal as well as some deformation and interlocking contact of metal to metal between the ferrule and the conductor. This extrusion, however, is accompanied by a lengthening of the compressed portions and by lateral extrusion if the metal of the ferrule is not confined throughout its entire periphery during crimping.

One object of the present invention is to provide an improved method of securing a ferrule to a conductor which roduces a permanent conductive connection having good resistance to stresses ordinarily encountered and which can be produced by application of pressures well within the limits of presently used crimping tools.

The invention accordingly involves application of crimping die pressure to the ferrule and the conductor enclosed therein while said parts are peripherally confined; and also can involve applying deforming pressure in opposite directions to alternating areas spaced longitudinally of the ferrule and staggered in opposite sides thereof; said pressure being exerted through the ferrule, upon the conductor enclosed therein. Thus, by moving toward one another opposed sets of crimping dies, the ferrule and the conductor pressed thereby are deformed and compressed to a substantially solid metal mass with accompanying compacting or coining of the metal of the ferrule with that of the conductor. A wiping component of the pressing movement of the crimping dies combines with the applied pressure to produce, in instances where desired, an optimum and durable conductive contact be tween opposed surfaces of the metal parts involved.

Said compressing and wiping actions applied to the ferrule and the conductor also can cause them to remain permanently connected and deformed in a substantially zig-zag interlocking relation to each other.

Patented Apr. 16, 1963 In practicing the invention, adequate shear stress can be exerted upon the conductor and the ferrule to produce such permanent interlock without impairing the parts involved where the die plates are arranged with suflicient clearance of their deforming die faces laterally from a shear plane so that no actual shearing of the metal occurs. This produces a good electrically conductive interlock of the ferrule and conductor of a character that will resist endwise pull; and the overlapping relation of portions of the die faces at their adjacent transverse edges, as said faces bear against the metal of the ferrule, produces a tight sheath-like fitting of the ferrule about the conductor.

Other objects and advantageous features of the invention to which reference has not been made above Will appear from the following description and the appended claim considered in connection with the accompanying drawings.

In this specification, I have described preferred procedures according to my invention; and the drawings illustrate appropriate, but not the only, kinds of apparatus for performing the steps of method involved therein. It is to be understood that these are not intended to be exhaustive nor limitin of the invention but, on the contrary, are supplied for purposes of illustration so that others skilled in the art may fully understand the invention, the principles thereof, and the manner of applying it in practical use, and will thus be enabled to modify and adapt it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 is a fragmentary view in side elevation of a press including a crimping die assembly embodying structural features and relationships of the parts designed for use in practicing the method and producing the crimped ferrule of the present invention;

FIGURE 2 is a view in end elevation taken from the right-hand end of FIGURE 1;

FIGURE 3 is a perspective view of portions of the upper and lower sets of dies included in the crimping die assembly illustrated in FIGURE 1;

FIGURE 4 is a fragmentary view on enlarged scale in elevation of portions of adjacent die plates of the die assemblies showing the offset relative positions of their respective die faces and With said die faces in open or ferrule-receiving position.

FIGURE 5 is a fragmentary view on enlarged scale in central longitudinal section through the crimping dies of FIGURE 1, with a plug type terminal therein and showing the condition and relative positions of the die faces, the ferrule and the conductor with the dies in maximum compressing and crimping condition;

FIGURE 6 is a perspective of a conductor and a plugtype terminal having its ferrule crimped into interlocking engagement with an end portion thereof in accordance with the present invention;

FIGURE 7 is an enlarged fragmentary view partly in transverse section on the line 7-7 of FIGURE 5;

FIGURE 8 is an enlarged fragmentary view partly in longitudinal section on theline 88 of FIGURE 7;

FIGURE 9 is a view in elevation of a hand-crimping tool with portions of the handles broken away and with a connector ferrule shown in position preliminary to application thereto of initial compression between the crimping dies;

FIGURE 10 is a fragmentary view in elevation taken from the left-hand side of FIGURE 9;

FIGURE L1 is a fragmentary view of the tool shown in FIGURE 9 with the parts arranged to permit free rotation of the die discs to position the proper die recesses thereof for crimping a particular size ferrule;

FIGURE 12 is a diagram on enlarged scale illustrating the dies wide open to receive a connector assembled on a conductor ready to be crirnped thereon;

FIGURE 13 is a diagram on enlarged scale illustrating the relative positions of the parts shown in FIGURE 9 when the dies are in maximum compressing position; and

FIGURE 14 is a fragmentary view in central longitudinal section on the line 1414 of FIGURE 13.

One form of equipment suitable for practicing the invention includes a die assembly which may be mounted in a standard press of the toggle, pneumatic or hydraulic type and conveniently employed for crimping a plug terminal or other connector having a wire-receiving ferrule. The terminal shown in FIGURE 6 initially has a substantially cylindrical ferrule, into which the end of a stranded conductor has been inserted. Upper and lower die carriers or holders 2 and 4, respectively, of such a standard press are mounted for rectilinear movement toward and away from each other. Other features of such apparatus are more fully described and shown in my copending application the said Serial No. 580,841 filed March 3, 1945, now Patent No. 2,639,754.

Said die holders 2 and 4, respectively, receive opposed upper and lower sets of crimping members. These include die plates 12, each of which has a ferrule-receiving recess 60a, FIGURE 3, recessed on its inner edge 12c presenting a die face 69 of smooth substantially cylindrical contour, and die plates 26, each having an abutment 64, FIGURE 4, extending up on its inner edge 26b and presenting a die face 66 of smooth substantially cylindrical contour.

The die plates 26 may advantageously be significantly wider or thicker than die plates 12, FIGURE 5, and are arranged in each holder with their inner straight edges 26b normally spaced from the opposed inner edges 120 of die plates 12 in the opposite holder and with their abutments 64 extending into said recesses 60a of the opposed die plates 12 in the other holder, FIGURE 3, and with the edges 64b of die faces 66 of said :abutments narrowly spaced from portions of the lateral confining wall surfaces of said recesses.

Holders 2 and 4 also carry a pair of cooperating dies 14, FIGURES 1 and 2, arranged with parallel edges interfitting as shown in FIGURE 2 and the ferrule-engaging and crimping faces 14c opposite. As shown in FIGURE 2, the interfitting edges 14b extend from the crimping face 140 of each die 14 closely fitting a lateral edge 14b of the opposed die 14. Thus, said die plates 14 enclose and confine the ferrule throughout the crimping operation as more fully described and claimed in the patent of Carlson No. 2,359,083, dated September 26, 1944. The die plates 12 and 26 likewise provide means by which a ferrule engaged between and pressed by said dies in crimping is confined against peripheral extrusion beyond the outer edges of the die faces 60 and 66.

In the illustrative form shown in FIGURE 1, the dies 12 and 26 are arranged in each of the carriers 2 and 4 in such manner that dies 12 in the carrier 2 are in staggered overlapping relation to the dies 12 in the other carrier 4; the dies 26 in each carrier are in staggered relation to the dies 26 in the other carrier and in opposed aligned relation to dies 12 therein; and die 14 in each carrier is opposite die 14 in the other carrier.

In determining the relative thicknesses of the die plates 12 and 26, it is desirable to provide sufficient diiference so that when the dies are pressed together, the lateral clearance between the overlapping faces of the dies 12 prevents cutting by shearing, but the clearance is sufiiciently small to assure a drawing of the edge of the ferrule into a continuous integral sinuous edge ferrule, as shown in FIGURES 6 and 8.

To facilitate such drawing and avoid cutting the metal of the ferrule when shear stresses are developed in crimp ing, the corners of edges 60 may be relieved to a short radius.

In using the apparatus above described, for purposes of the present invention, a terminal 57 with its ferrule encircling an end pontion of the conductor 59 is thrust into the space between said sets of dies when the latter are in open or extended relation, FIGURE 4. The ferrule part of said terminal is positioned between the upper and lower crimping dies, when die carriers 2 and 4 are moved toward each other, and thus the die faces 60 are brought into pressing contact with the ferrule, in spaced transversely disposed areas on each side, which areas at the upper side are in offset or staggered relation to those at the lower side thereof. At the same time the opposed dies 14 also move to engage the ferrule in a transversely disposed band.

Upon further movement of the dies 12 and 26 and While ferrule 57 is laterally confined by the vertical surfaces of die openings 68a, the ferrule and the conductor are compressed and deformed into a mass having a substantially lenticular or elliptical cross section of reduced area, as compared to the original cross section. Application of this pressure of the die surfaces 60 to the offset areas at opposite sides of the ferrule compacts the connection, but the most significant action is the crowding of the ferrule between the offset shear planes with consequent wiping action, pressing and scraping the wires in the zone between said shear planes.

Portions of the ferrule and of the conductor are deformed by each of dies 12 being forced into offset relation to adjacent portions of the ferrule and conductor and compressed against the opposite die face 66. This results in a compressed mass having a corrugated fold along its lateral edges and a zig-zag interlocking deformation of the ferrule and conductor.

In the form of crimping apparatus illustrated in FIG- URES 3 and 4, abutments 64 serve to limit deformation of the ferrule into the space between adjacent die plates 12 and, in effect, serve as anvils against which final pressure from the opposite die plates 12 is exerted. This produces thorough compacting of the metal mass in the crimped zones of the ferrule and extrusion of the ferrule and conductor metal which extrusion resists spring back of the ferrule or relaxing of the contact pressure on the conductor. Due to the fact that deformation of the ferrule results in a stretching of the ferrule in the corrugations concomitant with compression of the enclosed wire, any tendency to spring-back results in increasing contact pressure and not relaxing it.

The die apparatus shown in FIGURES 1-5 is designed for crimping a terminal or ferrule which can more conveniently be inserted between the dies by endwise or longitudinal movement. However, the method of the invention is applicable likewise to terminals and other connectors having portions of enlarged diameter, or of irregular shape, or such that they are more advantageously inserted laterally into the opening between the dies. One illustrative example of apparatus for this purpose is a hand tool, FIGURES 9 and 10, wherein cooperating sets of spaced dies plates 12a and 12b, respectively, each of generally circular or disc form, are mounted with peripheral portions of one set in over-lapped relation to peripheral portions of the other set. Said sets of die plates are rotatable to bring their approximately cylindrical die faces, as 600, into compressing engagement with a ferrule 57a when positioned in the ferrule-receiving recesses 60b. There the ferrule is compressed onto a wire 59a by actuating the dies with a rotary toggle motion which makes the connector in effect the pivot of a toggle and thus imposes a crimping force with great mechanical advantage. The resulting connection, FIGURE 14, is similar to the connection described above and resulting from the operation of dies 12.

In this tool of FIGURES 9 and 10, one set of said spaced dies, 12a, is p-ivotally mounted on a shaft 78 and another set 12b on a shaft 78a with peripheral portions of one set interleaved with and laterally clearing peripheral portions of the other. Dies 12a are rotatable as a unit on said shaft 78 and dies 12b as a unit on 7 said shaft 78a. Said shafts and their respective unitary die assemblies are supported on tie plates 76, one at each side of the tool, FIGURE 10, said tie plates being mounted on operating handles 72 which pivot on a shaft 74. End portions of said shaft 74 extend outwardly through and are slidable to and from end positions in vertical slots 86 in handles 72. A shaft supporting and locking plate 8-2 is slidably retained on tie plate 76 by headed pins 80 extending through horizontal slots 84 in said plate 82. The latter also has a right angle slot 96 with its vertical portion opening through the lower edge of plate 82. With the dies in open position to receive or discharge .a ferrule, FIGURE 12, the vertical part of slot 96 registers with vertical slot 86; and end portions of shaft 74 rest on the bottom end of said slot 86. With the dies in crimping position, an end portion of the horizontal part of slot 96 comes opposite the upper end portion of vertical slot 86; and shaft 74, resting on the bottom surface of said horizontal part of slot 96, is thereby supported in up position in said slot 86. A spring 90 looped around shaft 74 is arranged with its free ends bearing yieldingly against under portions of the handles 72 normally to bias said handles outwardly.

Upper edge portions of each handle 72 are provided with racks 70 which mesh with pinions 98 secured to the sets of dies 12a and 12b, respectively. Thus, when the outer ends of handles 72 are pressed toward each other with the locking plate 82 and other parts in positions as shown in FIGURE 9, racks 70 actuate pinions 98 which, in turn, rotate both sets of disc dies sufiiciently' to bring a ferrule 57a with its conductor into maximum crimping position between said sets of dies.

After crimping is complete, pressure on handles 72 is released; and spring 90 causes reverse movement of said handles back to the open position shown in FIGURE 9, where the cn'mped connection may be removed from the laterally open jaws.

When a different size ferrule is to be crimped, racks 70 may be disengaged from pinions 98 to permit rotation of the dies relative to the racks 70, FIGURE 12. To this end locking plate 82 is moved to the position shown in FIGURE 11. Thereupon the outer ends of shaft 74 drop to and rest on the bottom edge of vertical slots 86 in tie plates 76, and racks 70 are disengaged [from pinions 98. Hence said sets of dies are freely rotatable to any desired position, such for example as that shown in FIGURE 12, where the smallest die openings 6% are in position to receive or discharge a smaller ferrule than could be cri-mped in the dies operatively positioned as in FIGURE 9. With the dies thus positioned, the assembly is moved back into engaged position as shown in FIG- URE 9. Racks 70 are now reenga-ged with pinions 98 and locking plate 82 is moved to its ready position for crimping, where it supports the ends of shaft 74 in their upper end position in slots 86.

It will be observed that when the handles are retracted to the position shown in FIGURE 9, or even wider apart, the peripheral die openings 6012 are opened out so that connectors can be inserted for crimping and removed after crimping in a lateral direction.

As hand pressure is applied to the grip ends of handles 72, racks at the upper ends thereof move and rotate pinions 98 and the die sets to bring the ferrule-engaging die recesses 6% toward and into the maximum pressureapplying position shown in FIGURE 13, in which ferrule 57a and the conductor 59a are deformed transversely into a zig-zag crimp.

The parts thus connected by pressure form a mass wherein portions of the contacting metal surfaces of said parts are drawn or wiped together into a compact permanently conductive connection, FIGURE 14, having the desirable interlocking features first above described in relation to crimps prdouced by operation of apparatus of the type shown in FIGURES 1-5 inclusive.

It is an advantage of the method of the present invention that excellent results are obtained with soft highconductivity copper or aluminum or other metals. Use of the method of the present invention with brass, harder copper, or even relatively springy metal is also advantageous.

I claim:

The method of forming an electrical connection between a metal ferrule and at least one conductor which comprises inserting the conductor within the ferrule, and compressing said ferrule and conductor together over a plurality of transverse zones, said zones being compressed simultaneously while maintaining complete peripheral confinement of the ferrule throughout each zone at least during the final stages of crimping whereby adjacent zones are axially ofiset from each other and alternate zones are coaxial.

References Cited in the file of this patent UNITED STATES PATENTS 461,868 Fleming Oct. 27, 1891 963,394 Richardson July 5, 1910 1,550,900 Goodspeed Aug. 25, 1925 1,675,857 Liebowitz July 3, 1928 2,008,227 Reilly July 16, 1935 2,262,802 Hayden Nov. 18, 1941 2,276,140 Andren Mar. 10, 1942 2,359,083 Carlson Sept. 26, 1944 2,359,084 Carlson Sept. 26, 1944 2,382,292 Carlson Aug. 14, 1945 2,457,538 Dupre Dec. 28, 1948 2,551,299 Sowa May 1, 1951 2,554,813 Buchanan May 29, 1951 2,639,754 Macy May 26, 1953

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