US2945206A - Electrical connectors - Google Patents

Description

y 12, 1960 K. M. HAMMELL 2,945,206

ELECTRICAL CONNECTORS 2 Sheets-Sheet l Filed May 24, 1954 INVENTOR. Kem'per M. Hammeil July 12, 19 I K. M. HAMMELL 2,945,206

ELECTRICAL CONNECTORS Filed May 24, 1954 Y 2 Sheets-Sheet 2 8), IN VEN Kemper M. Ham-me BY III:

' disadvantages inherent in the prior art.

ELECTRICAL CONNECTORS Kemper M. Hammell, Harrisburg, Pa., assignor to AMP Incorporated, a corporation of New Jersey Filed May 24, 1954, Scr. No. 431,870

' 9 Claims. (Cl. 339-276) This invention relates to electrical terminals of the flag or lateral tongue type and more particularly to terminal ferrules or barrels from which a flag contact member extends so as to make an electrical connection with a conductor.

Heretofore, it has been the practice where a terminal of the flag type is desired to provide a contact member with a laterally extending tongue which, in application, is simply wrapped around a bared conductor. To secure the terminal on the wire, reliance is placed on tight wrapping of the tongue, or on brazing or other extraneous means. In the flag terminal any stresses imposed on the wire transversely of ferrule are amplifled, due to action at a moment arm equal to the diameter of the ferrule, and tend to unwrap the tongue where any significant lateral tension is involved, rendering the connection ineffective. Any opening of the ferrule, of course, decreases the electrical conductivity .Of the connection between the Wire and the contact member, but in addition, renders the contact surfaces accessible to corrosion. Such flag terminals are further limited in the application in that for each wire size, a separate size ferrule-forming tongue is required to obtain optimum ferrule formation. That is, the principle of crimping a ferrule having a given diameter onto wires of various sizes cannot be utilized with the simple wrapped barrel inasmuch as such ferrules cannot with- 2,945,206 Patented July 12, 1960..

tion; g

Figure 3 is a view in elevation of the connector blank strip taken along line 3-3 of Figure 2; t t

Figure 4 is a side view of the terminal in an intermediate stage in the applimtion thereof to an electrical conductor; 7

Figure 5 is a sectional view taken along line 5-5 of Figure 4; r

Figure 6 is a side view illustrating the terminal in the final stage of application to an electrical conductor;

-Figure 7 is a sectional view taken along line 7-7 of Figure 6;

stand thepressures involved in the crimping operation not along its length as is sometimes desirable.

It is, therefore, a primary object of this invention to. provide an electrical. connection of wide application and high quality but low cost. V

Another object of the. present invention is to pro vide an improved method and means for making a pressure formed electrical connection of the flag con tact type.

A further object is to provide i-na terminal of the dag type a ferrule capable of being applied to wire conductors of various diameters.

Still another object is to provide a method and means for positively locking the wire supporting ferrule of a terminal of the flag type.

A still further object is to provide a flag type terminal having a positively locked wire supporting ferrule which may be applied at any point along the length of a conductor by semi-automatic or automatic means.

Additional objects reside in the provision of a com merically feasible organization which will be substantially foolproof in use and overcomes certain well known Figure 8 is a side view of the terminal positionediin the applicator die prior to the application; .Figure 9 is a plan view of a connector blank strip illustrating an alternative embodiment of the presentinvenfion; p r, Figure 10 is a side view taken along line-j10'10 of Figure 9; v

"Figure 11 is a side view of the terminal of'Fig'ure9 in an intermediate stage of application thereof to' a conductor; f Figure 12 isv a view similar to Figure 11 illustrating the final formation of the ferrule asapplied to 'a cond-uctor; j K Figure 13 is a plan view of'another embodimentof the present invention and i V j Figure 14 is a fragmentary side view taken along line 14-14 of Figure 13. g

' Referring to Figure 1, there is shown an electrical connector or terminal which includes a contact member 1 of the flag or laterally extending tongue type, electrically coupled, in accordance with the principles of the present invention, either to the end or intermediate the length of an electrical conductor '2. The precise form and characteristics of contact member l are', in general, immaterial to my invention, but may typically take the form of a receptacle for a tab contact, as shown', or may simply be a ring or spade tongue for cooperation With a binding post or the like. In addition while my invention is to be primarily described in connection with connectors of the flag-type, it is within the purview of my invention that contact'member' 1 be positioned in'th'e more conventional endwise arrangement as desired; To allix the terminal to the conductor, a laterally extending tongue integral with contact member 1 is curled to form a wire supporting barrel or ferrule 3 about a bared portion 4 of conductor 2, the end of the tongue 7 being mechanically bonded to the terminal bodydescribed in detail hereinafter. Ferrule 3, being positively locked, is then capable of withstanding transverse stresses at least to the degree normally encounted in terminals of this type without uncurling of the ferrule-forming tongue. An additional ferrule 6, serving mainly to support the insulated portion of conductor, may be provided if desired. No great amount of lateral stress is involved in this function and accordingly ferrule 6 may be of the conventional wrapped form. Ferrule 6 additionally serves to prevent the conductor wire from being sharply bent,'and perhaps cut at the point of entering ferrule 3. In this connection to further insure against the wire being cut, the inner side edges of ferrule 3 may be chamfered or swaged, as at 12 in Figure 5,to bell the ferrule mouth and thus remove sharp corners at the'bending point. 7 7 v The terminals or connectors of my invention are contemplated to be formed from sheet metal material by conventional blanking techniques, a typical shape for the blank after leaving the blanking dies being generally designated at B in Figures 2 and 3. Preferably, theterminal. blanks are stamped in a continuous strip from sheet metal material whereby the terminals may be advantageously handled in reel form by automatic applicator machines, although my'invention also embraces terminal blanks in single form. In the connected strip, however, the blanks are joined end-toend by a connecting link 13 which is sheared oif the terminal body in the application of the terminal to a conductor. Link 13 in length will be dependent on the nature of contact member 1, and if sufliciently long such link provides a convenient means for carrying registration indicia, for example aperture 14, by which the feed of the strip within the automatic machines operating thereon may be controlled.

It is preferred that the terminal or connector blanks be partially preformed to the extent which facilitates application of the terminals, hence, the strip of blanks are formed, as exemplified by-the terminal blank generally designated at A in Figures 2 and 3, with the ferrule-forming tongues upstanding and slightly curled at the ends which simplifies the applicator die arrangement and operation as will be described. Where the terminal or connector is to be employed in circumstances where speed of application is relatively unimportant, for example in certain types of hand tool applications, the ferrules may be more fully or completely preformed to a cylindrical cross-section. In either case it is to be understood that the terminals in a given finally processed strip'will be substantially identical in shape, the transition from the generally flat form of blank B to the preformed or processedblank, such as blank A in Figure 2,- being accomplished by forming dies in successive stages according to techniques well-known in the art.

In the application of the terminal the wire supporting tongue is curled to a cylindrical cross-section" with the end thereof mechanically locked in position, the locking operation in the embodiment of my invention shown in Figures 1 to 8 involving significant bending and stressing of the sheet metal material from which the blank is formed. While the physical properties of the metal may be limited in selection and controlled by the characteristics desired in the terminal or connector. portion, such as contact member 1 which is of the spring contact type, in general the selection of the metalwhich is to form the ferrules and locking tongue therefor is restricted only to the extent that too hard a material may crack during application. For the connector illustrated in Figure 1, cartridge brass three-quarters hard gives the characteristics desired in the contact member shown, such material also being satisfactory for the purposes of my invention.

As shown in Figure 2, the blanks includea base section '7 which will provide the root or bottom portion of the ferrules to be formed. Contact member 1, by shank 5, is integrally connected to and extends laterally from one side from base section 7, while tongues 8 and 9, ultimately to form ferrules 3 and 6 respectively, extend from the other side of base section 7. Tongue 8 is reduced in width at. end portion 10 which is adapted to be inserted in a slot '11 in shank adjacent base section 7. A pair of opposed tabs 15 and 16, struck down from base section 7, provide means for locking tongue 8 at end in ferrule-forming position as will be more particularly described in connection with Figures 5 and 7. Broadly, however, tongue 8 is adapted to be curled or rolled around the; bared vportion 4 ofzconductor 2 andztongue 4 end 10 is threaded through slot 11 until shoulders 20, which serve to define the limit that end 10 projects heneath shank 5, abut the edges of slot 11. As shown in Figure 4, tongue end 10 is of suflicient length to extend along the underside of the base section 7 to a position between tabs 15 and 16 which provide when folded inwardly toward end 10 a positive lock for securing tongue 8 in ferrule-forming position. .From Figure 5 it will be observed that the width of tongue end 10, at the point to be'disposed' between tabs 15 and 16, is slightly greater than the distance between the points from which the tabs were struck whereby whenvthe tabs are moved against or embedded in the side edges of tongue end 10 a coining of the metal occurs resulting in an efficient and secure locking action.

In the application of the terminal, the conductor 2 is put in position along the length of base section 7 with the insulated portion thereof disposed adjacent tongue 9 and bared portion 4 adjacent tongue 8. Since the blank is formed from flat material,'in the formation of the ferrules the center lines of the insulated and bared portions of the conductor tend to be displaced which results in sharp bending and stressing of the bared wire at the point of entering wire supporting ferrule 3. Such stressing may be reduced bypre-curving in the production die that portion of base section 7 which supports the insulated conductor. a 'An important feature of invention resides in the capability of the terminal to accommodate wires of various sizes, and to insure good electrical conductivity characteristics the wire barrel should be crimped or indented so as to compact the metal of the bared conductor within the indented area. In the embodiment of the invention illustrated in Figures 1 to 8, the crimping or indenting action may be advantageously combined with the action required to lock the tongue end 10 in ferrule-form ing position. Hence, with locking tabs 15 and 16 centered on the longitudinal axis of base section 7, an indentor, striking the bottom'of base'section 7 across tabs 15 and 16, may effect the crimping and locking actions in a single stroke as will be explained.

Turning now to Figure 8, the applicator dies for affixing the terminal on a conductor typically comprise a movable upper die block 23, resiliently mounted lower block '25 serving to form the insulation barrel and preferably has a radius of curvature slightly tighter than the curvature of the insulated portion of the conductor 2 whereby tongue 9 will be tightly wrapped thereon. Die face 24 serves to form the wire barrel and, although having a radius of curvature slightly greater than the curvature of the wire sizes to be used for the given size terminal is primarily designed to curl tongue 8 into a generally cylin drical cross-section in a manner which results in tongue end 10 being threaded through slot 11. In, practice, upper die 23 may conveniently be formed by cutting die faces 24 and 25' in separate plates which are then secured together by any suitable means such as bolts. In this connection, as the insulation thickness for a given wire size may radically vary, the formation of die faces 24 and 25 in separate plates is preferred whereby theplates may then .be formed so as to be relatively adjustable to permit of the terminal while the ferrules are formed and crimped, a recess 30 curved to, conform with the base of the insulation supporting ferrule providing means for registering the terminal in the die nest. Slot 31, extending through die block 26 in alignment with the position at which the wire barrel is to be positioned, serves as a guide for bringing indentor 27 into engagement with the bottom of ferrule 3 at tabs 15 and 16 (see Figures 6 and 7). Lower die block 26 is resiliently mounted, as by springs 32, on a base 33 such that during, the final stages of applying a terminal as die 23 moves downwardly, die block 26 is forced towards base 33 against the tension of springs 32 to cause indentor 27, which has a generally elongated and rounded indenting surface, relatively to rise in slot 31 against the bottom of the wire barrel thereby to effect an indenting action as best shown in Figures 6 and 7.

With conductor 2 properly positioned, a bared portion 4 and aninsulated portion thereof lie within the partially preformed ferrules 3 and 6 respectively, and the upstanding tongues 8 and 9-projecting into the channels formed in the upper die block 23; the terminal is then ready to be applied .to the wire. As upper die block is moved downwardly, the pre-curled ends of tongues 8 and 9 are engaged by die faces 24 and 25 and further curled in conformance with the curvature thereof. In this connection it is to be understood that the force required to flex springs 32 is'greater than the force necessary to bend the relatively thin sheet metal constituting the ferruleforming tongues, hence die block 23 will engage shank 5 of the'terminal, at which time ferrules 3 and 6 will have be'en'substantially formed'as in Figure 4, before sufficient v forceis imparted through die block 26 to cause compression of springs 32. To insure that the insulation supporting ferrule tightly embraces conductor 2, die face 25 is designed so that the end of tongue 9 leaves the die channel prior to engagement of the upper and lower die block's; Since the tongue is being curled throughout the initial movement of the upper block, as the die blocks near one another a re -entrant curvature of tongue 9Jwill beeffect'ed, as best illustrated in Figure 4, to produce a tightly wrapped ferrule. Similarly, tongue end 10 is curled beyond the face of die 24 and into slot 11 until shoulders 20'engage shank 5, which occurs substantially in coincidence with engagement of the die blocks. Further'downward movement of block 23 results in a relative upward movement of indentor 27 which engages andbends tongue end 10' between the struckdown tabs 15 and 16 (see Figure 5). With the ferrules being constrained within the die blocks, further relative movement of indentor 27 folds tabs 15 and 16 into the side edges of tongue end 10 and effects an indenting action as shown in-Figures' 6 and 7. The depth of the crimp or indentatiorr'is predetermined in relation to the wire size of conductor 2 and the diameter of ferrule 3, being deeper for wires-of relatively small size for a given size ferrule, but inigeneral is sufliciently deep to produce a tight compacting of the wire within the ferrule without cutting the wire strands or substantially reducing the tensile strength thereof. s i

To provide for optimum locking of ferrule 3', asthe indentor moves upwardly, it should first engageand, force tongrieendlO against the bottom of base section 7 before folding tabslS and 16'inwardly so that there occurs a partial overlapping of the tabs behind the tongue end prior to the indenting action. To this end the indentor 27 "maybe preferably relieved, as at 35 in Figure 7, in the region'thereof which engages the tabs, although an advantageous locking action is obtained with the indentor face being linear. In either case, since tongue end 10 has 'a greater width than the distance between the tabs when closed, movement of the tabs toward the side edges of the tongue under pressure from. the indentor causes a coining and compression of the metal of the side edges of both the tabs and the tongue As a result the metal and lower edges of the tongue end thus assuring mainte nance of the tongue in ferrule-forming position against all lateral stresses normally encountered in. the ordinary use of terminals of this type. v

While indenting the ferrule to compact the conductor wire therein provides a tight connection which con siderable resistance to the longitudinal pullout of the Wire, the pullout and corrosion resistance may be substantially increased by serrating, as at 36, the inside of tongue 8. During indenting of the ferrule the metal of conductor 2 is caused to be extruded into serrations 36; as shown. in Figure 7, which substantially increases the longitudinal force required to pull the terminal along the wire and moreover provides a clean and intimate electrical connection between the terminal and the wire.

The greater the tongue length which must be threaded through slot 11, the more diflicult the threading operation becomes. In an alternative embodiment of my invention illustrated in Figures 9 to 12, a modification of the tongue locking arrangement permits an advantageous reduction in length of tongue end 10, and in addition, strengthens the ferrule by repositioning the locking tabs to shank 5 which is more capable of absorbing the stresses involved in the locking action. As shown in Figure 9, the substantially flat blank Ba and the partially preformed terminal Aa generally include a contact member 1a extending laterally from base section 7a and integrally connected thereto by shank portion 5a with tongue 8a extending laterally from the other side of the base section. Slot 11a, having a width sufficient to admit freely the tongue end, is formed in shankSajby striking down and bowing a tab 38 (see Figure 10). 'Upon tongue end 10a being threaded through slot 11a, forcefully straightening or flattening the bow in tab 38 pinches the tongue end which tendsto be reduced in thickness at the area of contact with the side edges of the slot. A combination latch-like and frictional gripping of the tongue results, the width of the slot now being less than the thickness of the tongue behind the slot. It will be understood, of course, that tab 38 is preferred not to have a length, when straightened, which will completely close slot 11a, a length which reduces the slot to the degree less than the thickness of the tongue necessary to provide an efficient frictional locksufficing. The latch-like grip may be beneficially made moreeffective by pro-reducing, as by lateral groove 39, the thickness of tongue end 1011, and, should base section 7a be precurved as in Figure 10, by providing a cooperating latch or detent 40 which extends from the bottom edge of slot 11a. 7 a

If desired, the insulation supporting ferrule may be omitted, such ferrule being replaced in Figure 9, by another wire supporting ferrule to increase the holding power of the terminal against longitudinal pull. In the absence of an insulation supporting ferrule, base section 70 is advantageously formed with a bowed or curved cross-section whereby to conform with the curvature of the conductor wire. In order that the wire barrel have substantially a cylindrical cross-section, slot l'la must be positioned adjacent the bowed portion of the base section thereby removing the sharp edge against which tongue end 10a may be pinched. Latch or detent 40 thereby becomes desirable to produce a sufliciently effective lockof thetab ends tends to cold-flow around both the upper ing action. p

The die block nest for applying the terminal is similar to that described in connection with Figures 6 to 8 and, in general, includes a ferrule-forming upper die block 23a for curling tongue 8a into substantially a cylindrical cross-section and threading the end thereof through slot 11a. Upon formation of the ferrule upper block 23a engages and forces downwardthe lower die block 26a which is resiliently supported by springs (not shown). Stationary indentor 27a in channel 31a relatively rises as lower block 26a is forced downwardly, and effects the compacting of the conductor metal withinrthe formed ferrule. Additionally channeled in lower block 26a is a, stationary anvil 41 which in concert with that flat under side 42 of upper block 23a, serves to straighten thebowed tab 38 substantially in coincidence with the indenting 'of the ferrule by indentor 27a asshown in Figures 11 and 12. It will thus be observed that as the end of tab 58 is forced against tongue end 10a, the coincidentally occur ring indenting action forces the lip of base section 7a, which includes'dete'nt 40, outwardlyagainstthe. other side of tongue end 10a, thereby assuring an 'elfective Where it is contemplated thatthe terminal is to be applied solely to aconductor end and the speed factoris unimportant, it may be desired to form the terminal strip with closed ferrules whereby to simplify the application of the terminals. The embodiments of my invention thus far described may obviously be performed as either opened or closed ferrule terminals. Another embodiment of my invention, as shown inFigures l3 and 14, illustrates a terminal having a ferrule arrangement which is especially suited to be locked during formation of the terminal strip. In this form the locking action is obtained by threading the tongue end 10b through slot 11b and folding the end along terminal shank b by any suitable means known in the art. The tongue end is locked in position by striking down a tab 45 from shank 511 into the upper surface of the tongue end as best shown in Figure 14. It remains, then, only to insert the wire within the closed ferrule and crimp the same to complete the application of the terminal; In this embodiment the indentation is preferably formed from the top of the terminal, as shown in dotted'lin'es in Figure 14,, the tongue end b tending to be Withdrawn through slot 11b, and hence into tighter engagement with the edge I of-the lanced tab 45 during the crimping operation.

- It is to be understood that the embodiment of Figures 13 and 14, similarly to the embodiments previously de scribed, may be formed with an open barrel wherein a wire is disposed along the ferrule before the barrel is formedand locked. In addition, similar to the embodi- V ment, the ferrules of the forms of my invention shown in Figures 1 to 12 may be indented from the top to provide the functions, of reducing the cross-section of the wire barrels around the inserted conductor. Combining the indenting action with the locking action is preferred, especially in connection with the form shown in Figures 1 to 8, since the indentation along the ferrule bottom tends to' increase the effectivenessof the lock.

Where the application of'the connector requires the ferrule to be of a spring metal of high resilience, the locking. feature of my invention becomes additionally important in that any tendency of the ferrule'to open, due to spring-back ,of; the metal after the'crimping dies are removed, is restrained.

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

I claim: a

1. A sheet metal electrical connector comprising a ferrule-forming portion including a base section and a tongue extending laterally from one side of said base section, a contact member having a shank extending from the other side of said base section, a slot in said shank adjacent said base section for receiving the end of said tongue upon formation of'the ferrule, and a pair of opposed tabs struck down from and along the longitudinal axisof saidbase section in substantial transverse alignment with said slot and said tongue, said end adapted to be disposed between and locked by said tabs in ferrule-v forming position upon centrally indenting theformed ferrule across said tabs, the Width of said end between said tabs being slightly greater than the distance between the points from which said tabs were struck. j

2. The method of forming a sheet metal connector on a wire which includes forming a contact member extension with a slot therein and a ferrule-forming tongue extension on opposed sides of a base section witha pair of opposed tabs struck down along the longitudinal axis thereof at points separated by less than the width of the end of the tongue extension, disposing the wire along the longitudinal axis of the base section, curling the tongue around the wire and threading theend thereofthrough the slot and between the tabs, and indenting the base section along a line including the tabs to compact the wire within the curled tongue and to coin the opposed edges of the tabs into and at least partially around the included portion of the tongue end. a

3. The method of forming a sheet metal connector on a wire which includes forming a contact member exten sion and a ferrule-forming tongue extension on opposed sides of a base section, opening a slot in the contact ex: tension to a width at least asgreat as the thickness of the tongue, curlingthe tongue around the wire and threading the end thereof through the slot to form a ferrule, and closing the slot to a width less than the thickness of the tongue.

4. The method of forming the connector on a wire including the steps of forming a lateral tongue with a tongue extension on a side ofacentral section of a wider strip of sheet metal, forming an opening in the connector opposed to the extension on the other side of the central section, curling the tongue around the wire to form with the central section a ferrule and threading the extension through the opening, and locking the tongue extension on the underside of the connector.

, 5. The method of forming a sheet metal connector on a wire which includes the steps of'forrning the contact member extension and a ferrule forming tongue extension on opposed sides of a base section, fashioning an opening adjacent the base section of a width at least equal to the thickness of the tongue extension and through which the tongue end portion is threadable, curling the tongue around a wire to form with the base section a ferrule and threading the end portion through the opening, and relatively closingthe opening to a widthless than the thickness of the threaded end portion to secure the tongue in ferrule-forming position. 3

6. An electrical connection with a wire, a sheet metal connector including a base sectionalong which. said wire is disposed, a tongue extending laterally from one side of said base section, an opposed contact member extending laterally from the other side of' said base section, said tongue being wrapped tightly around said wire with the end thereof threaded through a slot in said otherlside and folded against the under side of the connector, and fastening means on said underside engaging the tongue end to secure thetongue in wrapped position;

7. An electrical connection according to claim 6 where'- in said fastening means includes a pair-of opposed tabs depending from said base and engagingopposite sides of the tongue end.

8. An electrical connection according'to claim 6 whe'rein said fastening means includes a pair of opposed tabs depending down from the base section, the tongue end being disposed'between and gripped by said tabs, the wire being compacted within the ferrule formed by the tongue and base section by an indentation extending across the the connector adjacent the side of the base section from which the contact member extends dimensioned to pass therethrough the end portion of the tongue extension, disposing a wire along the base section, wrapping the tongue extension around the wire and threading the end portion through the opening, and relatively closing the opening to dimensions less than that of the threaded through end portion to secure the tongue in ferrule forming position.

References Cited in the file of this patent UNITED STATES PATENTS 10 Kulier Nov. 20, 1923 Bagley May 12, 1925 Rowley Feb. 13, 1934 Rogoff May 2, 1944 vBuchanan July 3, 1945 Pontius Apr. 20, 1948 Bergan May 29, 1951 Macy June 19, 1951 Matthysse Feb. 19, 1952 Carlson May 13, 1952 FOREIGN PATENTS Germany Apr. 22, 1954

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