Electrical means and method of making at least a portion of the same

3,283,291

Nov.

Filed

1, 1966

April 8,

ELECTRICAL

1964

S. J. KROL ETAL

MEANS AND METHOD OF MAKING AT

LEAST A PORTION OF THE SAME

Sheets-Sheet 1

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ELECTRICAL MEANS’aN^METHOD^OF MAKING AT ^,283,291

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Filed April 8, 1964

Sheets-Sheet 2

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United States Patent Office

3,283,291

Patented Nov. 1, 1966

3,283,291

ELECTRICAL MEANS AND METHOD OF MAKING AT LEAST A PORTION OF THE SAME

Stanley J. Krol, Chicago, and Lester B. Johnson, Des Plaines, III., assignors to United-Carr Incorporated, a corporation of Delaware

Filed Apr. 8, 1964, Ser. No. 358,318

Claim. (Cl. 339—276)

This invention pertains to wire wrappable electrically conductive means and to electrically interconnecting means such as, for instance, electrical contacts having extending portions for wire wrapping. The invention also pertains to the making of such means in the case of the first named means and such extending portions in the case of the second named means.

A principal object of the invention is to provide means as above indicated which are novel.

It is also an object of the invention to produce means as first indicated above and extending portions of the second indicated means by novel methods.

Other objects, advantages, and features of the invention in its various aspects and forms or variations will appear in the course of reading and considering the following description in conjunction with the accompanying drawing in which:

FIG. 1 is a fragmentary, cross sectional view, enlarged many times through an insulative body showing a pair of contacts embodying a preferred form of the invention, one of the contacts being shown broken for convenience of illustration while the other contact is shown fragmentarily;

FIG. 2 is a fragmentary, longitudinal sectional view through the insulative body taken along line 2—2 of FIG. 1 and in the direction of the arrows, the view showing one of the contained contacts;

FIG. 3 is a fragmentary, top plan view of the insulative body with the two contacts shown in FIG. 1 and at the same scale as that figure;

FIG. 4 is a more greatly enlarged cross sectional view taken along line 4—4 of FIG. 2 and in the direction of the arrows;

FIG. 5 is an end view, at the same scale of FIG. 5, of a blank portion from which the tail portion of the contact shown in FIG. 4 is largely formed;

FIG. 6 is a subsequent intermediate form of the blank portion of FIG. 5 within which a piece of wire is contained therealong;

FIG. 7 shows a still later form of the blank portion containing the wire of FIG. 6;

FIG. 8 is a fragmentary, cross sectional view of an insulative body mounting another form of contact from which contact a piece of piano wire is shown being removed from inside the tail portion thereof to produce .he finished hollow tail portion of the contact;

FIG. 9 is a more greatly enlarged cross sectional view taken along line 9—9 of FIG. 8 and in the direction of the arrows;

FIG. 10 is a view like FIG. 6 but during the process of making still another form of contact tail forming die means also being shown;

FIG. 11 is an end view of the finished tail construction of the form being made in FIG. 10;

FIG. 12 is a view like FIG. 10 but during the process of making yet another form of contact tail forming die means also being shown, and

FIG. 13 shows an end view of the finished tail construction being made in the last view.

Referring to the drawing figures in detail and first to FIGS. 1 through 7 thereof, the reference numeral 1 generally designates a body of electrically insulative material such as a suitable plastic for instance having a rec10 tangular slot 2 extending vertically downwardly from the upper surface of the body. A plurality of spaced cavities 3 extend outwardly from and along the opposite sides of the slot 2 (only two oppositely disposed cavities being shown in the drawing).

Restricting our attention to a single cavity 3 and contained contact 11 which are shown complete in FIGS. 1-3 of the drawing realizing that the other cavities and contacts are the same, -said cavity 3 communicates to the outside of the body through the bottom surface of the body by means of a laterally centrally disposed, rectangular, vertically extending opening portion 6.

The contact generally designated 11 and constructed of a single piece of suitable thin sheet material such as spring temper phosphor bronze except for the inner portion of the tail is mounted within the cavity 3 depending therefrom through the opening portion 6 of the body cavity. The contact 11 has an upper portion 13 slotted from 14 to the end 15 thereof and which extends partly into the slot 2 of the body 1 and is outwardly resiliently compressible upon insertion of a printed circuit board of slightly less width than that of the slot 2 within said slot for electrical engagement with conductive means on the face of the printed circuit board adjacent thereto. The contact is also provided with a pair of shoulders 16 which engage the bottoms of a pair of grooves 4 along each side of the cavity 3 to limit downward movement of the contact during mounting of the latter within the body 1.

The contact 11 is also provided with a vertically extending tail generally designated 19 of square outer form except for the uppermost portion 20 thereof which is slightly longer than it is wide in cross section which latter portion is preferably quite snugly received within a rectangular opening portion 6 of the body cavity 3 in the fore and aft direction. The lower end of the tail 19 is swaged at each of the four sides thereof at 21 to assist insertion of the contact within the body during mounting of the contact within the body. The slightly smaller square configuration of the principal portion 22 of the tail relative to the upper portion 20 thereof also facilitates such insertion of the contact within the body during mounting of the former, the larger portion 20 making a snug reception of the contact within the opening portion 6 of the body cavity in the fore and aft direction as previously noted at the end of the insertive movement only. The tail portion 19 is also dimpled on one side at 23 to cause a certain pressing out or bulging of the tail at 24 normal to the dimpled surface to prevent any upward movement of the contact within the body, thus, with the engagement of the shoulders 16 of the contact within the body, to immovably mount the contact within the body.

Considering the tail portion 19 of the contact more specifically, the same consists of an outer portion 25 and an inner portion 26 preferably of soft copper wire (see FIG. 4), the outer portion 25 being a lower part of the rest of the contact which has been formed around the inner portion 26 and comes together along a vertically disposed seam line 27. FIG. 4 discloses the nature of this tail portion 19 which portion constitutes a solid tail having very sharp outer edges or corners extending vertically therealong up to the portion 20 for good electrical engagement with one or more wires to be wire-wrapped around the square portion 22 of the tail in a conventional manner.

The tail portion 19 of the contact is formed by first forming a lower flat blank portion 28 shown in FIG. 5 preferably of uniform width therealong into the pre-form 29 shown in FIG. 6 either directly or by intermediate steps. A piece of round, preferably dead soft copper wire 26 of at least approximately the length of the pre3,283,291 form and the tail portion 19 of the completed contact is placed or forced down within the slightly U-shaped central trough 30 of the pre-form. The distance across the top of the U-shaped trough is such as to provide a slight interference fit between the wire 26 and preform 29 to retain the former within the latter during subsequent movement or handling of the pre-form. The opposite, upwardly extending sides 31 of the pre-formed 29 are then caused to be substantially closed by suitable die procedure into the cylindrical form shown in FIG. 7 in which the copper wire 26 is at least relatively tightly received therewithin.

The pre-form shown in FIG. 7 and the contained soft copper wire 26 are then caused to be changed in shape by tight squeezing on four sides thereof by the use of suitable stationary as well as moving die means into the form shown in FIG. 4 having the sharp edges or corners above noted and entirely filled at the interior of the outer portion 25 by the soft copper wire which has become squared up by the compacting or compression process. It is pointed out in this connection that the distance across each of the pairs of opposite sides of the finished square tail shown in FIG. 4 is somewhat less than the diameter of the round wire and the two thicknesses of sheet material shown in FIG. 7.

Thus, a solid, square tail has been provided from a thin flat blank portion and a piece of round, inexpensive wire having the very sharp corners or edges necessary for good electrical engagement with the wrapping wire or wires. It is pointed out in this connection that the corners or edges may vary from substantially no radii or curves to radii or curves of about .003 of an inch. The thickness of the sheet metal of which the contact is largely constructed is, of course, several times thicker than this as for example .008 or .0100 of an inch. The solid, tightly contained, at least somewhat interlocked interior of the tail together with the outer portion 25 thereof provides a solid tail structure which is very strong in resisting torsional stress during the process of wire wrapping which, of course, is achieved by the use of an automatic wire wrapping gun. Also, the soft, deformable copper wire filling the entire interior of the outer portion 25 of the contact tail as it does under the extremly high compression or pressure exerted on the outer portion and contained wire during the formation of the square tail portion prevents the entry of any plating fluids into any crevices between the portion 25 and wire for the causing of subsequent corrosion in the tail portion. Further still where the contact is plated with precious metal such as gold for better conduction of electrical current into and from the contact, the solid interior of the tail portion prevents plating of the inside of what would otherwise be a hollow tail portion resulting in great saving of the extremely costly precious metal.

The flat blank portion 28 need not necessarily be formed into the pre-form 29 but the same may be formed directly or in other stages into the cylindrical form shown in FIG. 7, the piece of wire 26 being dropped or placed within the portion 28 prior to its closure into the FIG. 7 form.

Although the use of a round wire has been disclosed, the concept of the invention does not bar the use of certain other shapes of wire or the equivalent, especially oval or polygonal with many sides, should the same be procurable and desired.

It is pointed out in order to complete the description that the upper portion 20 of the tail 19 is not pressed or formed into sharp edges or comers as is the portion 22 but the comers are considerably or broadly rounded so as to provide the additional material for the generally rectangular and some what larger shape of said portion 20 for the snug reception of the same within the body opening 6 in the direction previously mentioned.

It is further pointed out that the presence of the wire 26 serves as a mandrel or inner backing member at least partly around which the blank portion 28 is formed or substantially closed, the wire also serving as a mandrel or inner backing member, even though the same is of soft copper, against which the outer portion 25 is pressed and reshaped into the square formation having the sharp corners shown particularly in FIG. 4. The presence of the inner wire portion 26 or the solid nature of the tail portion 19 also either permits or makes much easier the dimpling of the tail portion at 23 to effect the previously mentioned retention of the contact in its mounted relation within the body 1.

FIGS. 8 and 9 disclose another form of contact where plating with precious metal is not had and where the added strength of a solid tail is not deemed absolutely necessary or where this strength factor is compromised. This contact is substantially like the previous contact except that a snap-in feature is employed (not shown) to retain the same within the body 34 and a piece of round, spring steel piano wire 35 is employed as the mandrel or inner backing member in place of the soft copper wire used in the first form.

The flat blank portion equivalent to 28 of the previous form and not shown in the drawing may be pre-formed in the same manner or manners indicated for the previous form so as to extend around the piece of piano wire into a form like that shown in FIG. 7 and in substantially the same tight relation with the wire as that existing between the outer portion 25 of the contact and the soft copper wire 26 shown in that figure whereupon such pre-form together with its contained piece of piano wire is pressed or forced under pressure by suitable die means as indicated in connection with the first form into the square tail form in FIG. 9 providing the sharp or quite sharp corners previously indicated for the tail of the first form. It should be noted from FIG. 9 that unlike the first form the hard piano wire 35 retains its round shape throughout the squaring up process applied to the outer portion 36 and that said outer portion although square on the outside conforms to the round wire on the inside thereof at 37 to at least substantially fill up the space between itself and the inner wire member 35. It should also be noted that there is a certain substantial thinning of the outer member 36 along the central portion of each of the four sides at 38 by virtue of the hard piano wire being therewithin against which the outer portion 36 is pressed under high pressure in effect representing a cold flowing of metal away from such central portions in both directions therefrom towards the corners.

After the squaring up of final forming step, the piece of piano wire 35, which is of a longer length than the tail portion 36 of the contact, is pulled out from within the formed tail portion as indicated by the arrow in FIG. 8 to be used over and over again or repeatedly with other contact blanks as a tool for the forming of other square tail portions in the same means as above indicated. The high tensile strength of such piano wire, of course, permits such withdrawal which would be impossible in the case of soft copper wire such as that used in the first form. The saving of the wire 35 and its repeated use, of course, substantially reduces the cost of the contact over that of the first form in which the somewhat expensive copper wire is left within the formed sheet metal constituting the outer portion of the tail while still permitting the very effective and inexpensive making of the square tail portion with the sharp edges for wire wrapping as disclosed from a thin, flat blank portion.

Although the piece of piano wire 35 has been depicted as being left within the substantially closed, sheet metal portion, like the outer portion shown in FIG. 7, from the time such portion is closed around the same until after the square tail portion is completely formed as indicated in FIG. 9, the piece of piano wire around which said sheet metal portion is substantially closed may actually be pulled out therefrom after the closure thereof and a like piece of piano wire mounted parallel to the first and with

3,283,291 a pointed free end inserted within the central opening of the substantially closed sheet metal portion after automatic movement thereof, for instance, to a new position or station adjacent to its former one and in position to receive the second mentioned piece of piano wire to place the substantially closed sheet metal portion in readiness for the production of the finished, square tail portion with the wire therewithin as previously indicated after which the second wire is also pulled out from within the contact tail. The above pulling out of one wire and insertion of a second may be necessary for high speed, automatic production, the two pieces of wire in such a case being mounted on a single, reciprocally movable piece, the first wire always being moved axially onto position relative to a flat blank portion or a partially formed condition thereof for the closure thereof around the wire while the second wire is always axially inserted within the hollow interior of a substantially closed, sheet metal portion which was closed around the wire just before the movement of such portion to the next station in front of the second wire.

Although the principal or wire wrappable portions of the tails of the above disclosed forms have been described as being square, the same could also be rectangular, if desired, or even of other polygonal shape so long as substantially sharp corners or edges are existent or said tail portions could be generally polygonal with concave or convex side surfaces producing the sharp edges or even with slightly raised edge portions along each side of a pair of opposite sides thereof extending inwardly from the edges no more than about two or three thousandths of an inch to assure that the corners or edges will not exceed a curve or bluntness of more than about two or three thousandths of an inch.

Although the outer, sheet metal portion 25 of the tail portion 19 of the contact disclosed in FIGS. 1 through 7 has been disclosed as being closed about the contained soft copper core or reshaped wire 26, such closure is not essential to the overall invention. FIG. 11 shows another form of tail construction in which the outer, sheet metal portion 41 does not so close or extend entirely around the soft copper core 42 thereof but rather such outer portion extends along three sides of the inner portion 42 and only a small part of the third having a very substantial, central gap 43 between its ends 45 and 46 which extend along the length of the tail portion in much the same fashion as does the seam 27 so extend along the tail portion 19 of the first form. The present form of tail construction has the same four exterior sharp comers or edges extending therealong as in the first form for a good electrical connection of the wire or wires wrapped therearound as in the case of the first form. It is also pointed out that the present tail construction is square in general outline as is the tail of the first form, that is, the principal or wire wrappable portion 22 thereof. It should also be noted that the inner member or core 42 is somewhat indented at 47 under the gap 43 between the ends 45 and 46 of the outer portion 41 which indentation is caused by the central, longitudinally extending portion 48 of the punch or movable portion 49 of the die means shown in FIG. 10 as a result of downward movement of the die portion 49 from the position thereof shown in FIG. 10 during the making or forming of the tail portion of FIG. 11. The inner portion or core 42 is also tightly received in substantially the same fashion as the core 26 of the first form of contact tail. In the present form, as is quite evident from viewing FIG. 11 of the drawing, the ends 45 and 46 of the outer portion 41 are somewhat inturned over the inner portion or core 42 to further interlock and retain the inner portion 42 from lateral movement from within the outer portion 41.

The tail construction of FIG. 11 is formed or produced partly from a flat blank portion similar to 28 of FIG. 5 but of somewhat less width and a piece of wire 42 identical to that of FIG. 6. The flat blank portion is formed into a U-shaped intermediate form 53 shown in FIG. 10 by suitable die procedure whereupon the form 53 is loosely dropped or placed within the longitudinal groove 54 in a stationary die piece 55, the form 53 being at least relatively snuggly received within the groove 54 in the transverse or cross-wise direction. The punch or movable die piece 49, which closely fits within the groove 54 at its lower portion 56 thereof, is then moved down within said groove under great force as far as it can go to compact and form the U-shaped portion 53 of the contact and wire 42 which latter has previously been dropped or placed within the center portion of the Ushaped member in snug reception therewithin along its length, into a generally rectangular solid form having the sharp or square corners or edges previously indicated and with the ends 59 and 60 of the form 53 turned inwardly into a condition like that shown in FIG. 11. During the downward movement of the die portion 49, the inner, soft copper wire portion 42 is caused to be cold flowed or squeezed under pressure so as to fill the entire interior of the outer, sheet metal portion except for the upper, relatively slight indentation caused by the portion 48 of the die piece 49. After production of the form just mentioned, the form is then subjected to a final squaring up by the use of suitable die procedure to make its sides exactly equal to each other in length and otherwise place the tail portion in the FIG. 11 form and condition rather than the tail portion being somewhat wider than it is high as it comes from the die means 49, 55. The tail construction of FIG. 11, therefore, has the benefits of the FIGS. 1 through 4 form while at the same time being cheaper because of the use of less material in the outer, sheet metal portion 41 because of the gap at 43 which material is relatively expensive.

FIG. 13 discloses another form of contact tail construction which is similar to the last form in that the outer, sheet metal portion 64 thereof does not extend entirely around the inner or core portion 65 but extends only along three sides thereof as is evident from the drawing. This form constitutes a substantially solid tail merely having an indention of its inner member or of core 65 at the top and has four sharp, coextensive corners or edges 66, 67, 68, and 69 extending at least the principal distance therealong for the same good electrical contact making engagement of a wire or wires wrapped around the tail portion as previously covered in connection with all of the previous forms. In the present form of FIG. 13, the outer, sheet metal portion 64 has a pair of opposite, longitudinally extending indentations 71 and 72 which project within the inner portion or core 65 to positively interlock the latter within the outer portion 64 to prevent any upward lateral movement (as viewed in FIG. 13) of the inner portion from said outer portion. The inner, wire portion or core 65 is also otherwise tightly received within the outer portion 64 as indicated in connection with the previous forms, the inner portion completely filling the interior of the outer portion except at the top thereof as previously noted.

The form of FIG. 13 is produced partly from a flat blank portion similar to 28 of FIG. 5 but of a somewhat different width which blank portion is formed into a Ushaped intermediate form 75 (see FIG. 12) extending upwardly substantially farther than the U-shaped form 53 of FIG. 10. The form 75 also snuggly receives a soft copper wire 65 which is identical to the piece of wire 42 and also 26 of the other forms, prior to the changes in shape thereof during the formation of the tail constructions, which wire 42 is dropped or placed within the open interior of the form 75 for the snug reception therewithin and confirmation of the form 75 with the arcuate lower half of the round wire 65 as seen in FIG. 12. The Ushaped form 75 with its contained wire is then dropped or placed in snug reception within a groove 78 in a stationary die portion 79 which is equivalent to the die portion 55 shown in FIG. 10.

A punch or movable die portion 81 of the configura3,283,291 tion indicated in FIG. 12 is then placed within the upper portion of the groove 78 filling the crosswise extent thereof and moved downwardly under great force to produce a generally rectangular form of solid tail portion resembling the form of FIG. 13 although of somewhat greater 5 crosswise extent than height. During the downward movement of the die portion 81, the opposite, coplanar, longitudinally extending shoulder surfaces 82 engage the coplanar, upper end surfaces 83 of the U-shaped form 65 to produce a medially located, inward collapsing or χθ buckling of the extra material which is provided in each of the rather long legs 84 of the U-shaped form- 75 which inner buckling displaces the soft copper material of the core 65 during the formation process of the tail. The buckling just described, of course, produces the longi- 15 tudinal indentations 71 and 72 shown in FIG. 13. The central, downwardly projecting, longitudinally extending portion 85 of the movable die portion 81, which fits snugly between the legs 84 of the U-shaped form 75, of course, prevents the ends 86 of the form 75 from turning 20 inwardly during the downward movement of the die portion to force the inward buckling of the form 75 at 71 and 72 after the lower sharp corners of the generally rectangular form have been produced at 87 of the die portion 79. The portion 85 of the die piece 81 is also 25 responsible for the lower top level or recessed nature of the inner portion or core 65 relative to the top surfaces 83 of the outer, sheet metal portion 64 of the tail construction shown in FIG. 13. Subsequent to the formation of the generally rectangular form produced by the 30 die means 79, 81 shown in FIG. 12, such compressed and pre-formed tail portion is then squared up by inward pressing of the opposite, buckled or indented sides by suitable, flat faced, movable die means while being retained in its height or vertical measurement between a 35 pair of oppositely disposed, stationary die portions to produce the generally square outer configuration of the tail portion disclosed in FIG. 13. FIG. 13, construction, as is quite obvious, effects a very substantial savings of material of the outer, electrically conductive sheet metal which, 40 of course, brings down the cost of contacts employing this construction a very substantial amount while such tail construction is quite effective as a solid type, wire wrappable tail having four sharp, longitudinally extending edges for such wrapping. ⁴³

As should be gathered from certain of the above information, variations and different embodiments of the invention including variations and different forms of the method or process for making the tail portions may be ⁸ .

had and are in fact had in mind and, therefore, it is desired that said invention be limited only by the terms of the appended claims read in the overall broad light of the invention and by the applied art. In this connection, the wire wrappable means forming part of the invention need not necessarily be an extending portion of a contact or other electrical interconnecting means but the same can be part of some other electrical equipment or device or even be a separate member for interconnecting two or more wires which are wrapped around such member.

Use of such terms as “depending,” “upper,” “vertical,” “inwardly” or other indications of directions are, of course, relative to the positions of the various parts as shown in the different drawing figures and accordingly are not to be construed in their absolute senses.