US3522577A

US3522577A - Electrical connector and method and apparatus for making same

Info

Publication number: US3522577A
Application number: US733597A
Authority: US
Inventors: Alfred M Zak
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-05-31
Filing date: 1968-05-31
Publication date: 1970-08-04
Anticipated expiration: 1987-08-04

Description

Aug. 4, 1970 M, ZAK 3,522,577

ELECTRICAL CONNECTOR AND METHOD AND APPARATUS FOR MAKING SAME Filed May 31, 1968 2 Sheets-Sheet l INVENTOR.

ALFRED M. ZAK

ATTORNEYS ELECTRICAL CONNECTOR ANDQMETHOD AND APPARATUS FOR MAKING SAME Filed May 31, 1968 A. M. ZAK

Aug. 4,1970

2 Sheets-Meet 2 FIG; 6

FIG. 8

INVENTOR. ALFRED M. ZAK

ATTORNEYS United States Patent 3,522,577 ELECTRICAL CONNECTOR AND METHOD AND APPARATUS FOR MAKING SAME Alfred M. Zak, 6110 Casmere Ave., Detroit, Mich. 48212 Continuation-impart of application Ser. No. 713,041, Mar. 14, 1968. This application May 31, 1968, Ser. No. 733,597

Int. Cl. H01r 11/20 US. Cl. 339-95 14 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for forming wire grip serrations on an electrical connector wherein a series of saw tooth-shaped ribs or serrations are formed on the inside or wire gripping face of the connector and a series of saw tooth-shaped grooves are formed on the outer side of the connector. The saw tooth-shaped teeth and grooves are formed by a punch and'die wherein the punch is formed with a series of saw tooth-shaped grooves and the die is formed with a series of saw tooth-shaped projections in opposed relation to the grooves for displacing metal into the grooves and thereby form the ribs.

This application is a continuation-in-part of my prior co-pending application Ser. No. 713,041, filed Mar. 14, 1968 and entitled Electrical Connector and Method and Apparatus for Making Same.

This invention relates to electrical connectors and more specifically to the wire grip portions of electrical connectors.

In my said prior application there is disclosed several embodiments of wire connectors wherein the wire grip portions thereof are defined by a series of ribs on one side of the wire grip portion and a series of grooves on the other side of the wire grip portion, the ribs and grooves being in only partially overlapping relation. It is pointed out in my prior application that the formation of wire grip portions in this manner possesses numerous advantages. It results in economy from the standpoint of the cost and maintenance of tooling; it results in an increase of the wire holding strength of the wire connector without increasing the size of the wire and without increasing the crimping pressures and facilitates the forming of such wire terminals in a conventional multi-station progressive die assembly.

The present invention involves the formation of ribs or serrations in the wire grip portion of a terminal in somewhat the same manner as disclosed in my prior applica tion but utilizing a die and punch shaped and arranged somewhat differently than disclosed in my prior application. In accordance with the present invention, the metal deforming surfaces of the punch and die are defined by a series of saw tooth-shaped projections and recesses which are designed to form on the wire grip portion of the connector a series of saw tooth-shaped ribs on the one side thereof and a series of saw tooth-shaped grooves on the othe side thereof. As disclosed in my prior application, the ribs are preferably formed as protrusions on the inner side of the wire grip portion and the grooves are preferably defined by recesses on the outer side of the wire grip portion.

In the drawings:

FIG. 1 is a fragmentary elevational view, partially in section, of a wire having an electrical connector formed in accordance with the present invention secured to the end thereof.

FIG. 2 is a sectional view along the line 2-2 in FIG. 1.

FIG. 3 is a fragmentary perspective view of a punch and die arrangement according to the present invention for forming the Wire grip portion of the connector.

FIG. 4 is an elevational view of a punch usable in the punch and die arrangement illustrated in FIG. 3.

FIG. 5 is a fragmentary plan view of a strip of sheet metal stock from which the connector is formed and showing in a condensed form progressive stages of formation.

FIG. 6 is a perspective view of a modified form of die according to the present invention.

FIG. 7 is a fragmentary plan view of the wire grip portion of an electrical connector formed by utilization of a die such as shown in FIG. 6.

FIG. 8 is a sectional view along the line 8-8 in FIG. 7.

FIG. 9 is a sectional view along the line 9-9 in FIG. 8.

FIG. 10 is a sectional view along the line 10-10 in FIG. 8.

FIG. 11 is a view illustrating a different punch and die arrangement according to the present invention.

FIG. 12 is a fragmentary sectional view showing a Wire grip serration on an electrical connector of conventional construction.

In FIG. 1 a female electrical connector, generally designated 10, is formed at one end with a cylindrical barrel portion 12 for receiving the cylindrical barrel portion 14- of a male connector 16. Connector 10 is formed adjacent its other end with a wire grip portion 18 and an insulation grip portion 20. Such connectors are usually formed in a progressive die assembly from a strip of resilient sheet metal such as brass. A strip of such metal, designated 22, is shown in FIG. 5. As the strip is fed through the successive stations of a progressive die assembly in the direction of the arrow in FIG. 5, it is initially formed with a series of indexing pin holes 24. The connector is then blanked from a strip to the configuration shown at 26 after which the serrations 28 are formed in the wire grip portion 18 at a successive station. At a further station the wire grip portion 18 and the insulation grip portion are bent into U-shape as indicated at 30 to receive the end of a wire. The connectors remain attached to the continuous edges of strip 22 by lugs 31 so that they may be wound into a coil (not illustrated) from which they are severed when the connectors are eventually crimped on the ends of wires.

In the showing of FIG. 5 only those forming operations relating to the wire grip portion 18 and the insulation grip portion 20 are illustrated. As a consequence, in actual practice there are one or more stations in the die assembly between the blanking station and the station that forms the serrations 28 and also one or more stations between the serration forming station and the station at which the wire grip and insulation grip portions are formed into U-shape.

A portion of the station of the progressive die assembly at which the serrations 28 are formed is generally illustrated in FIG. 3. The vertical reciprocating punch assembly comprises a punch retainer 32 in which a rectangular cavity 34 is ground for receiving a punch member 36 with an insert plate 38 at each side thereof. The stationary die assembly at the wire grip forming station comprises a die retainer 40 in which a rectangularly shaped cavity 42 is ground for receiving a composite die comprising a die block 44 which is slotted to receive a die member 46. Cavity 42 also receives a die block 48 for initially forming the insulation grip portion 20 of the connector. Die block 44 is formed with inclined abutments 50 at each side of die member 46 for coining the opposite lateral free edges of wire grip portion 18. Die block 48 is fashioned with similar abutments 52 for coining the opposite free lateral edges of insulation grip portion 20.

Die member 46 is in the form of a blade fashioned with a series of spaced saw tooth-shaped teeth 54 ground into the upper end of the blade. The crest of teeth 54 are separated by saw tooth-shaped grooves 56 therebetween. Teeth 54 protrude upward above the top flat reference face 58 of the die, or, stated differently, teeth 54 protrude upwardly above die level. Punch member 36 has a series of saw tooth-shaped grooves 60 ground into the lower end thereof which define therebetween a series of saw tooth-shaped teeth 62. The crests 64 of teeth 62 are flush with the lower flat reference face 66 (FIG. 8) of the punch. When the punch and die components are assembled as shown in FIG. 3, the teeth 54 form a series of spaced projections which protrude above die level 58 and grooves 60 form a series of spaced cavities in the fiat reference surface 66 of the punch assembly.

In view of the manner in which the serrations are formed on the wire grip portion of the connector in accordance with the present invention, punch member 36, as illustrated in FIG. 3, may be made substantially wider than die blade 46 and formed with a series of teeth 62 at each of the four corners thereof (FIG. 4) for a purpose explained more fully hereinafter.

In FIG. 6 there is illustrated a modified form of blade type die 68 generally similar to that illustrated at 46 in FIG. 3 except that the teeth are not formed as continuous ribs across the thickness of the blade but rather as a series of small saw tooth-shaped teeth 70 spaced apart transversely by cross grooves 72. These individual teeth 70 are formed simply by grinding grooves 72 perpendicularly to the grooves 56 in the end face of blade 68.

FIG. 8 shows the appearance of the ribs and grooves formed on the opposite faces of the wire grip portion 18 in accordance with the present invention. In view of the section along which FIG. 8 is taken, the particular cross section illustrated in FIG. 8 is typical of the cross section of the wire grip portion of the terminal regardless of whether the blade 46 or the blade 68 is used in the die section. Thus, even though FIG. 8 is a sectional view taken in FIG. 7, the line along which this section is taken is such that the cross section of the wire grip portion along this line is representative of the cross section obtained using either die blade 46 or die blade 68. In both cases the teeth (70 or 54) are formed with inclined faces 74 which terminate in crests 76 and have vertical end faces 78. Likewise, the teeth 62 on punch member 36 are fashioned with inclined faces 80 which terminate in the crests 64 and have vertical end faces 82. In the arrangement illustrated in FIG. 8 faces 80 incline downwardly and to the left and faces 74 incline upwardly and to the right. The insulation grip portion 20 of the terminal is located at the left of FIG. 8. The crests 76 and the crests 64 are generally aligned in a vertical direction. The serrations on the wire grip portion are thus defined by a series of generally saW tooth-shaped ribs 84 on the inner or upper side of the terminal and a series of saw tooth-shaped recesses 86 on the outer side of the terminal. Ribs 84 are defined by generally flat faces 88 which incline upwardly or inwardly of the terminal in a direction opposite to the insulation grip portion 20. These saw tooth ribs 84 terminate in a slightly rounded crest 90 and a vertically extending end face 92. Grooves 86 define therebetween ribs which, likewise, have inclined faces 94 terminating in rounded crests 96 and vertically extending end faces 98.

In the arrangement shown in FIG. 8 the end faces 98 of ribs 95 are generally vertically aligned with faces 92 of ribs 84. If the punch and die are staggered as shown in FIG. 11 so that the teeth 62 of the punch are offset relative to the grooves 56 in the die, then the crests 100 of the ribs 102 formed on the inside of the wire grip portion are staggered relative to the crests 104 of the ribs 106 formed by the recesses on the outer side of the wire grip portion. In FIG. 11 the punch and die are staggered so that end faces 82 on the punch are located approximately mid-way between end faces 78 on the die. Thus crests 100 on the inside of the wire grip portion are backed up to a substantial extent by crests 104 on the outer side of the wire grip portion of the connector. In either event, when the punch and die are closed upon the sheet metal as shown in FIGS. 8 and 11, the metal is displaced vertically and preferably also laterally to produce serrations with the saw tooth configuration illustrated in the wire grip portion.

When a die section such as shown in FIG. 6 is utilized the wire grip portion has less undisturbed metal as compared with a wire grip portion where the ribs extend continuously across the full width. The metal of the connector registering with grooves 72 is undisturbed when the punch and die are closed upon one another. This is the section of metal designated 108 in FIG. 9. Each rib of the wire grip portion is defined by a series of spaced humps 110 extending in rows across the wire grip portion rather than as a continuous rib having the configuration shown at 84 in FIG. 8. In this arrangement a cavity 112 underlies each rib hump 110. The cross channels or cross grooves 72 may be formed if desired on the die member or on both the punch and die members. In either case, assuming the same wire size and the same crimp height, since less metal in the strip is deformed, the pull strength of the connector would be somewhat less than that obtained where the ribs extend continuously across the wire grip portion of the connector such as by the arrangement illustrated in FIG. 3. However, the die illustrated in FIG. 6 permits the formation of deeper ribs and thicker connecting portions between the ribs.

When the Wire grip portion of the present invention is crimped around the end of a wire in the conventional manner illustrated in my prior application, the crests 90 of ribs 84 penetrate into the outer strands of the wire as shown in FIG. 2 and, thus, result in a wire grip having a relatively high pull strength. This results from the fact that the ribs 84 project inwardly of the U-shaped wire grip portion. 'These ribs not only penetrate into the outer strands but they immediately transmit to the interior strands 122 of the wire a relatively high pressure. In the case of a multi-strand Wire ahigh pull strength is obtained only if the exterior and the interior strands are subjected to relatively high pressure when the connector is crimped on the end of the wire.

In a conventional wire grip serration (FIG. 12) the ribs 124 are formed on the outer side of the Wire grip portion and a groove 126 is formed on the inner side directly opposite each rib. When the wire grip is crimped each rib is displaced inwardly to the broken line position indicated 128. When a conventional wire grip is crimped the serrations do not penetrate substantially into the outer wire strands and the interior strands are not subjected to considerable pressure. With the wire grip serration disclosed herein the holding power of the terminal is further increased by the fact that the saw toothshaped ribs 84 are inclined in a direction opposite to the wire end of the connector so that a relatively severe straightening of the wire strands is required to pull the wire out of the wire grip portion.

As mentioned previously, when a die blade such as shown in FIG. 6 is employed less metal is disturbed. This enables the formation of deeper ribs and this results in a deeper penetration into heavier gauge wire. The die blade illustrated in FIG. 6 thus adapts the connector for use with heavier gauge metal and heavier gauge wire where it is desirable to form less teeth so as to reduce the tonnage or pressure required in forming the teeth and where a greater penetration into the wire is permissible.

As pointed out in my prior application, the tooling required for forming wire grip serrations in accordance with the present invention can be produced economically. Punch member 36 can be formed as a blade wherein the grooves 60 are ground directly across the end of the blade rather than being formed as a cavity. When the punch is formed in a blade of the type shown in FIG. 4,,

each of the four corners of the blade may be employed successively as the blade wears before the blade has to be either replaced or reground.

I claim:

1. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a series of inwardly projecting ribs thereon which extend transversely of and are spaced apart lengthwise of the wire grip portion, said ribs defining grooves therebetween, said inner face having a smooth portion surrounding said ribbed portion, said outer face having at the portion thereof juxtaposed to the inner ribbed portion a series of inwardly extending grooves thereon, said grooves extending transversely of the wire grip portion and being spaced apart lengthwise thereof, the portions of said outer face between said last-mentioned grooves being substantially flush with the ungrooved portion of said outer face the portion of said inner face between said ribs being flush with said smooth portion, each of said ribs being in staggered overlapping relation with the grooves on the outer surface to the extent that each rib overlaps about half of the portion of the outer face between the grooves thereon.

2. An electrical connector as called for in claim 1 wherein each rib is of saw tooth shape.

3. An electrical connector as called for in claim 2 wherein each rib has a wire engaging face which protrudes from said inner face in a direction inclined opposite to the wire retaining end of the connector.

4. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, each of said faces having on juxtaposed portions thereof generally saw tooth-shaped ribs and grooves, the crests of the ribs on one face lying generally in the plane of said one face and the crests of the ribs on the other face pro truding from the plane of said other face.

5. An electrical connector as called for in claim 4 wherein the crests on the ribs on said inner face are 1ocated at the edge of the ribs opposite the wire engaging end of the connector.

6. An electrical connector as called for in claim 4 wherein the ribs on one face overlap the ribs on the other face such that the crest portions of the ribs on one face are generally opposite the crest portions of the ribs on the other face.

7. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a plurality of radially inwardly extending protrusions which are spaced apart both lengthwise and transversely of the wire grip portion so as to form intersecting grooves therebetween, some of said grooves extending lengthwise and the others extending transversely of the wire grip portion, said portion provided with said protrusions being surrounded by a generally smooth portion which is substantially flush with the bottom of said grooves, said outer face having at the portion thereof juxtaposed to said inner portion formed with said protrusions a plurality of recesses therein, said recesses being spaced apart lengthwise and transversely of the wire grip portion and registering radially with said protrusions, the portions of said outer face between said recesses being generally smooth and being substantially flush with the portion of said outer face surrounding said recessed portion.

8. An electrical connector as called for in claim 7 wherein the opposite side edge portions of said protrusions which extend lengthwise of the wire grip portion are defined by generally rounded shoulders which provide the grooves therebetween extending lengthwise of the wire 'body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a series of inwardly projecting ribs thereon which extend transversely of and are spaced apart lengthwise of the wire grip portion, said ribs defining grooves therebetween, said inner face having a smooth portion surrounding said ribbed portion, said outer face having at the portion thereof juxtaposed to the inner ribbed portion a series of inwardly extending grooves thereon, said grooves extending transversely of the wire grip portion and being spaced apart lengthwise thereof, the portions of said outer face between said last-mentioned grooves being substantially flush with the ungrooved portion of said outer face and the portion of said inner face between said ribs being flush with said smooth portion, each of said ribs being of saw tooth shape and the bottom faces of the grooves on the outer face being inclined so as to extend generally parallel to said wire engaging faces of said ribs.

10. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a series of inwardly projecting ribs thereon which extend transversely of and are spaced apart lengthwise of the wire grip portion, said ribs defining grooves therebetween, said inner face having a smooth portion surrounding said ribbed portion, said outer face having at the portion thereof juxtaposed to the inner ribbed portion a series of inwardly extending grooves thereon, said grooves extending transversely of the wire grip portion and being spaced apart lengthwise thereof, the portions of said outer face between said last-mentioned grooves being substantially flush with the ungrooved portion of said outer face and the portion of said inner face between said ribs being flush with said smooth portion, said ribs forming a series of generally saw tooth shaped protrusions on the inner face of the wire grip portion and said grooves in the outer face forming a series of generally saw tooth shaped indentations in said outer face.

11. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a series of inwardly projecting ribs thereon which extend transversely of and are spaced apart lengthwise of the wire grip portion, said ribs defining grooves therebetween, said inner face having a smooth portion surrounding said ribbed portion, said outer face having at the portion thereof juxtaposed to the inner ribbed portion a series of inwardly extending grooves thereon, said grooves extending transversely of the wire grip portion and being spaced apart lengthwise thereof, the portions of said outer face between said last-mentioned grooves 'being substantially flush with the ungrooved portion of said outer face and the portion of said inner face between said ribs being flush with said smooth portion, each of said ribs comprising a series of saw tooth shaped projections spaced apart in a direction transversely of the wire grip portion.

12. An electrical connector comprising a sheet metal body having a wire retaining end provided with a wire grip portion of generally U-shape, said wire grip portion having an inner wire engaging face and an outer face, said inner face having at a portion thereof a series of inwardly projecting ribs thereon which extend transversely of and are spaced apart lengthwise of the wire grip portion, said ribs defining grooves therebetween, said outer face having at the portion thereof juxtaposed to the inner ribbed portion a series of inwardly extending grooves thereon, said grooves extending transversely of the wire grip portion and being spaced apart lengthwise thereof, the portions of said outer face between said lastmentioned grooves being substantially flush with the ungrooved portion of said outer face, the inner wire engaging face of each rib being inclined in a direction lengthwise of the wire grip portion and the bottoms of the grooves in said outer face being generally similarly inclined as the wire engaging faces of said ribs.

13. An electrical connector as called for in claim 12 wherein each rib comprises a series of saw tooth shaped projections spaced apart in a direction transversely of the wire grip portion.

References Cited UNITED STATES PATENTS 3,020,520 2/1962 Berg 339-273 3,112,150 11/1963 Hammell 339-276 3,293,355 12/1966 Gropp et a1 174-84 MARVIN A. CHAMPION, Primary Examiner J. H. MCGLYNN, Assistant Examiner US. Cl. X.R.