US3883212A

US3883212A - Contact for multiple conductor connector

Info

Publication number: US3883212A
Application number: US295759A
Authority: US
Inventors: Josef Keglewitsch
Original assignee: Bunker Ramo Corp
Current assignee: Amphenol Corp
Priority date: 1970-08-17
Filing date: 1972-10-06
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13

Abstract

Contact formed of single piece of thin sheet metal, using a single thickness of the sheet metal for a flexible blade at one end and multiple folded thicknesses at the other end for a compact rigid post with sharp corners to receive a wrapped-wire termination. The direction in which folded layers extend permits the construction to be adapted to formation of posts of increased rectangular cross section, without alteration of the clearance between adjacent contacts in a multiple-conductor connector.

Description

United States Patent 1 1 Keglewitsch May 13, 1975 [54] CONTACT FOR MULTIPLE CONDUCTOR 2.870.241 1/1959 Mason 174/94 3,283,291 11/1966 Kroll et a1 339/276 A CONNECTOR 3.288.915 11/1966 Hatfield et a1. 339/276 A [75] Inventor: Josef Keglewitsch. Addison, Ill.

[73] Assignee: Bunker Ramo Corporation, Oak Primary Examiner-Joseph H. McGlynn Brook. Attorney. Agenl. 0r Firm-D. R. Bair; F. M. Arbuckle [22] Filed: Oct. 6, 1972 [211 App]. No.: 295,759 [57] ABSTRACT Related U.S. Application Data Contact formed of single piece of thin sheet metal. 3 Continuation f Sen N 64313 Aug [970 using a single thickness of the sheet metal for a flexiaband0n ble blade at one end and multiple folded thicknesses at the other end for a compact rigid post with sharp [52] US. Cl 339/276 A; 29/630 R; 174/94 S Corners to receive a wrapped-wire termination. The [51] Int. Cl H01r 9/14 direction in which fol l yer xtend permits the [58] Field of Search 339/95. 97-99, Instruction 1 be adapted to formation of posts of in- 339 7 27 174 94; 29 30; 35 11 creased rectangular cross section. without alteration of the clearance between adjacent contacts in a multi- [56] Referen e Ci d ple-conductor connector.

UNITED STATES PATENTS 4 Claims, 9 Drawing Figures 266,511 10/1882 Perkins 85/11 'IIIIIIIIIA CONTACT FOR MULTIPLE CONDUCTOR CONNECTOR CROSS REFERENCE TO RELATED APPLICATION This application is a continuation in part ofa copending application, Ser. No. 64,313, filed Aug. 17, I970, abandoned.

BACKGROUND OF THE INVENTION Electrical connectors of the type shown in Yopp US. Pat. No. 3,002,176 have been mass-produced and used in large quantities for many years, principally in a style to which the associated wires are attached by soldering. The present day need for automation in wiring procedures gives rise to a demand for a connector essentially the same as that in the Yopp disclosure, except arranged to have the conductors leading to the individual contacts thereof applied by the so-called wire-wrap technique rather than by soldering. The wire-wrap technique, now well known in the electronic arts, consists essentially of winding several turns of the stripped end of a flexible insulated wire around a rigid, sharpedged terminal or post" so that the sharp edges of the post impinge into the convolutions of the wire enough to hold the wire in position on the post and establish an intimate, low resistance electrical contact without the need of solder. Unfortunately, the inherent design of the contacts of the Yopp connector is such that modification to accomodate the wire-wrap technique introduces conflicting engineering requirements in the design thereof. It is obviously desirable to have each contact formed of a single piece of metal, yet it is necessary that the active portion of the contact (that is, the portion which engages a mating contact of another connector) be flexible and springy, and therefore rather thin, while at the same time it is essential that the wire-wrap post be of heavy cross-section compared to the thickness of the active portion, so that it will be relatively rigid and unyielding, even during application of forces incident to the wire-wrapping procedures.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solution to the conflicting physical requirements just mentioned, and further, to provide a style of contact which, with relatively minor changes in design, can be made with wire-wrap posts of various sizes, adapted for different ranges of wire-gauge or diameter. A further object is to provide for the possibility of various sizes of wire-wrap posts, on contacts which are otherwise the same, and which can be accommodated interchangeably in the same connector bodies with limited centerto-center contact spacing.

In furtherance of these objects, the invention consists of an elongated contact formed integrally from a single piece of sheet metal, in which one end of the contact includes a flexible contact blade of a single thickness of the metal, the intermediate portion of the contact is formed as a channel of appropriate shape to fit into a mounting recess in an insulating connector body, and the other end is folded, formed and compacted to constitute a post appropriate for receiving a wrapped wire termination.

The post in cross-section appears as a channel, with a web which is in the same plane as the web of the channel in the intermediate portion. The post web extends transversly a distance approximately 4 times the thickness of the metal, and has flanges at right angles to the web, extending a distance at least 4 times the thickness of the metal. Each flange then reverts by an inward fold back toward the web. The entire cross-section is compacted by a squeezing or swedging operation to force all elements of the configuration into contact with adjacent ones and to reduce the corners of the section to a small radius. The section can be approximately square, accommodating wire up to a certain maximum size, or can be rectangular, by making the flanges extend a distance more than 4 times the thickness of the metal, thus making a post which ac commodates a somewhat larger wire size.

DESCRIPTION OF THE DRAWINGS The invention is described in further detail in connection with the accompanying drawings in which:

FIG. 1 is an enlarged side elevational view of a contact formed of a single piece of metal in accordance with the present teaching;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a further enlarged cross-sectional view through the wire-wrap post portion of the contact, taken on the line 3-3 of FIG. 2;

FIG. 4 is a view corresponding to that of FIG. 3, but showing a modified form of rectangular cross-section;

FIG. 5 is a view showing a wire-wrap connection around the post of FIG. 3;

FIG. 6 is a view showing a wire-wrap connection around the post of FIG. 4;

FIG. 7 is a fragmentary face view of a dielectric body for a multiple-contact connector of the kind in which the contacts are used.

FIG. 8 is a longitudinal section view taken on the line 8-8 of FIG. 7, showing a plurality of contacts in place; and

FIG. 9 is a cross-section taken on the line 99 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The complete contact, best illustrated in FIGS. I and 2 of the drawings, consists in its essential parts of a blade" or active portion 10, a mounting shank 11, and a terminal portion 12.

The blade is the active portion of the contact, in that it is the part which resiliently engages a similar contact carried in a mating connector body, and also is the only portion which moves during the normal functioning of the connector. The mounting shank 11 is of channelshaped formation and is designed to seat in a rectangu- Iar aperture 41 in the insulating body 20 of the connector, to position the blade 10 within the body, and to give support to the terminal portion 12. The terminal portion 12 is adapted for attachment of a conductor, usually a flexible insulated wire.

The blade portion 10 comprises a reversely curved, flexible, and somewhat springy segment 13 having a smoothly rounded contacting surface with a protuberance 14 on its forward face to engage a mating contact, and a horseshoe bend 15 at the extreme end of the blade, terminating in an anchor portion 16 designed to limit the flexing movement of the contact and permit initial spring bias thereof toward the contact of an opposing connector. The blade is formed of a single thickness of sheet metal, cadmium copper and beryllium copper being widely used materials.

The mounting shank 11 has a back wall or web 17 which is essentially a continuation of the spring blade 13 but is provided with a pair of side flanges l8 and 19 (FIG. 2) so that it is of channel shape in cross-section. The side flanges I8 and 19 have outwardly projecting

steps

21 and 22 forming abutments which position the contact in the cavity 41 in the dielectric body in which it is mounted. The contact is inserted in the body 20 by passing the terminal portion 12 through the cavity in the body. A bendable locking tab 24, when bent outwardly after insertion of the contact in its cavity, serves to retain it therein.

To facilitate description in this specification, and to avoid prolixity and ambiguity in the claims, conventional rectangular coordinates are used for defining direction and planes, and the applicable axes are identified in FIGS. 1, 2, 3, 4 and 8.

Thus, for example, what may be considered the original plane of the parent sheet metal from which the contact is formed, seen in the web 17 of shank 11, the immediately adjacent portion of spring blade segment 13 and the web 28 of terminal 12, is the X2 plane.

The long dimension of a cross-section of blade section 13, as shown in FIG. 9, is in the X direction, and the thickness of the cross-section is in the Y direction. The direction in which the spring blade moves in flexure, indicated by the double arrow 25 in FIG. I, is the Y direction.

The novelty of the present disclosure resides in the terminal portion 12. This terminal, according to the present invention, consists of a straight, slender, yet rigid post, having sharp edges or corners extending along its length, and adapted to receive a wire coiled there-around by an automatic wire-wrap machine.

As previously mentioned, it is essential, in order to get the desired degree of flexibility in the blade portion of the contact, to form it of relatively thin sheet metal. In the practical manufacture of contacts in accordance with the Yopp disclosure, metal strip having a thickness of 0.006 inch is used. Since this thickness of metal does not, of itself, have sufficient strength nor rigidity to serve as a wire-wrap post, the present disclosure proposes to form the post by folding several thicknesses of the metal back upon themselves, utilizing right-angle bends and channel-shaped sections to provide the required rigidity.

This is illustrated in FIG. 3, which shows a channelshaped section made by bending the opposite edges of the metal blank from which the post is formed in two 90 bends at 26 and 27 to define a back web 28 lying in the X2 plane, as a continuation of web 17, and two

side flanges

29 and 30 extending from the web 28 in the Y direction. As seen in the cross-section in FIG. 3, the width of the web, that is, its X dimension, is approximately 4 times the thickness of the metal. The

flanges

29 and 30 extend in the Y direction to a dimension four times the thickness of the metal, or more, as will be later explained. The flanges are then doubled inwardly and back upon themselves in two 180 bends in the

areas

31 and 32, and the blank is so dimensioned that the marginal edges of the reentrant side flanges extend the full depth of the channel and up to the web 28.

The normal bending operation leaves a radius on the outside corners somewhat greater than is desirable for the optimti'm bite" into a wire wrapped on the termiiial. comer 'radii of less than 0.003 inch are considered tiesii'able. The sharp corners may be formed by wellknown methods, which in this case may be variously referred to as swedging, spanking or coining. For example, two opposite sides of the post may be pressed together, while the other two opposed faces are confined in an appropriate die or cavity. As one result of such a compacting operation the metal is forced into the corners of the confining die, and the desired sharper corners are formed. As another result, the several adjacent folds of sheet metal are pressed flat against each other in surface-to-surface engagement throughout the length of the segments or folds involved. Voids or spaces are largely eliminated and the actual metallic cross-section available within any specified exterior dimensional limits is maximized. The mutual support provided by the intimate engagement of each fold with its neighbor provides rigidity for the post closely approaching that of a solid member of the same external dimensions.

Contacts of the kind described herein are used in connectors which have a molded insulating body, a typical body 20 being shown in face view in FIG. 7, and in longitudinal section in FIG. 8. This is the body for a receptacle, which has an elongated cavity 40 adapted to receive a mating plug, not shown. The body is adapted to support a plurality of contacts along each of the long sides of the cavity. Holes 41 extend through the body, and the contacts are retained therein by the

steps

21 and 22 and the tab 24, as shown in FIG. 1.

In FIG. 8 the contacts are shown in place in the body, and the purpose of FIG. 8 is to illustrate the closeness of the X-direction center-to-center spacing of adjacent contacts. This distance, C-C in FIG. 8, is 0.085 inch in a type of connector which has become a standard by its extensive manufacture and use over many years. It is obvious that the clearance space available in the X direction between adjacent terminals 12 leaves very little space for operation of the wire-wrap tool, especially next to a terminal on which wire has already been wrapped. Furthermore, the distance between the wire wrap coils on adjacent terminals is a minimum desirable from the reliability standpoint, in view of various risks, among which may be mentioned the possibility of accidental bending of the elongated terminals, or of arc-over from transient voltage pulses.

The maximum size of wire which can be used on a wire-wrap post is determined to a major extent by the ability of the post to withstand, without damage, the twisting forces to which it is subjected as the wire is wrapped around it. The post shown in section in FIG. 3, when made from metal stock of 0.006 inch thickness, is about 0.025 inch square in external dimension, and can be used with copper wires up to a maximum of No. 28 B.&S. gauge, or a maximum of 0.0l 2 inch diameter. Such usage is illustrated by the wire in FIG. 5.

For many purposes it is desirable to use a larger and less delicate wire, capable of carrying more current. In order to use a larger wire without damage to the terminal post, it is essential to have a post of heavier crosssection. The center-to-center spacing considerations described above make it impractical to increase the X- dimension of the post. However, in the construction taught by this invention, it is possible to have the flanges wider, in the Y-dimension, as shown at 29 and 30' in FIG. 4. The flange width can be as much as 8 times the thickness of the metal, with a considerable increase in the cross-sectional area of the post, its torsional and beam strength, and thus in its ability to withstand the twist of larger wire. A post 0,025 X 0.045 can be used for wire up to 26 8.818. gauge. On the rectangular post, the larger wire 50' winds in an oval conformation as seen in FIG. 6, so that its extension beyond the sides 29 and 30' of the post is very little greater than that of the smaller wire 50 in FIG. 5.

From the foregoing it will be apparent that by virtue of the teachings of the present disclosure, connectors of a type heretofore mass-produced in a design suitable only for utilization by soldering techniques may be produced in a design suitable for wire-wrap termination without any change in the exterior connector parts or their dielectric inserts, and with no change in functioning of the active portions of the contacts nor their mountings, and thus with no need for utilization of new or different assembly procedures, tooling, etc

Furthermore, it is possible to provide contacts for different ranges of wire gauge sizes, such contacts being interchangeably usable in a connector in any arrangement desired. These advantages are obtained without sacrifice of the inherent advantage of one-piece contact construction, even though the proper functioning of the finished connector requires certain portions thereof to be quite flexible and somewhat springy while other portions must be almost completely rigid.

Certain preferred embodiments have been described, but without limitation of the scope of the invention other than as it is defined in the following claims.

I claim:

1. A contact element for electrical connectors, formed of a single, integral piece of sheet metal, having an active portion at one end including a flexible contact blade,

a terminal portion at the other end, and

a mounting shank between said active portion and said terminal portion, said shank being of channel shaped cross-section, with an intermediate web between two flanges,

wherein said terminal portion is characterized by a crosssection including a channel with a back web coplanar with the intermediate web of said shank, and two side flanges, one at each side of said back web and extending at right angles thereto to a width at least as great as the width of said back web, said side flanges being reentrant back upon themselves by 180 bends whereby they extend inwardly to the full depth of the channel and into close contact with said back web and with each other.

2. A contact element for electrical connectors, formed of a single piece of thin sheet metal, having an active portion at one end including a flexible contact blade,

a terminal portion at the other end, and

a mounting shank between said active portion and said terminal portion.

and wherein, in terms of rectangular coordinates, the

major dimension of said contact may be defined as being in the Z axis, the long dimension of a cross section of said blade adjacent to said mounting shank is in the X axis, the thickness of said crosssection of said blade is in the Y axis, and said blade is adapted to flex so that its elements move princi pally in the direction of the Y axis, said terminal portion being characterized by a crosssection throughout its Z dimension comprising a channel having a back web extending in the X direction to a width four times the thickness of the metal, side flanges extending from said web in the Y direction at least four times the thickness of the metal, said side flanges being doubled inwardly and back upon themselves and extending the full depth of said channel and up to the web. 3. A contact element for electrical connectors, formed of thin sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, said mounting shank being formed in a channel shaped cross-section with two flanges and an intermediate web, and wherein, in terms of rectangular coordinates, the major dimension of said contact may be defined as being in the Z axis, the long dimension of a crosssection of said blade adjacent to said mounting shank is in the X axis, the thickness of said cross section of said blade is in the Y axis, and said blade is adapted to flex so that its elements move princi pally in the direction of the Y axis, said terminal portion being characterized by a cross-section throughout its Z dimension comprising a channel having a back web coplanar with the intermediate web of said mounting shank and extending in the X direction to a width four times the thickness of the metal, side flanges extending from said back web in the Y direction to a width between 4 and 8 times the thickness of the metal, said side flanges being doubled inwardly and back upon themselves and extending the full depth of said channel and up to the back web. 4. A contact element for electrical connectors, formed of a single piece of thin sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, and wherein, in terms of rectangular coordinates, the major dimension of said contact may be defined as being in the Z axis, the long dimension of a crosssection of said blade adjacent to said mounting shank is in the X axis, the thickness of said crosssection of said blade is in the Y axis, and said blade is adapted to flex so that its elements move principally in the direction of the Y axis, said terminal portion being composed of four compactly-pressed laminations of said sheet metal, the two outer laminae being joined by a web integral therewith, perpendicular thereto and extending in the X2 plane, and the edges of the inner laminae adjacent to the web of said terminal portion being pressed into closely abutting relation thereto.

Claims

1. A contact element for electrical connectors, formed of a single, integral piece of sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, said shank being of channel shaped cross-section, with an intermediate web between two flanges, wherein said terminal portion is characterized by a crosssection including a channel with a back web coplanar with the intermediate web of said shank, and two side flanges, one at each side of said back web and extending at right angles thereto to a width at least as great as the width of said back web, said side flanges being reentrant back upon themselves by 180* bends whereby they extend inwardly to the full depth of the channel and into close contact with said back web and with each other.

2. A contact element for electrical connectors, formed of a single piece of thin sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, and wherein, in terms of rectangular coordinates, the major dimension of said contact may be defined as being in the Z axis, the long dimension of a cross-section of said blade adjacent to said mounting shank is in the X axis, the thickness of said cross-section of said blade is in the Y axis, and said blade is adapted to flex so that its elements move principally in the direction of the Y axis, said terminal portion being characterized by a cross-section throughout its Z dimension comprising a channel having a back web extending in the X direction to a width four times the thickness of the metal, side flanges extending from said web in the Y direction at least four times the thickness of the metal, said side flanges being doubled inwardly and back upon themselves and extending the full depth of said channel and up to the web.

3. A contact element for electrical connectors, formed of thin sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, said mounting shank being formed in a channel shaped cross-section with two flanges and an intermediate web, and wherein, in terms of rectangular coordinates, the major dimension of said contact may be defined as being in the Z axis, the long dimension of a cross-section of said blade adjacent to said mounting shank is in the X axis, the thickness of said cross-section of said blade is in the Y axis, and said blade is adapted to flex so that its elements move principally in the direction of the Y axis, said terminal portion being characterized by a cross-section throughout its Z dimension comprising a channel having a back web coplanar with the intermediate web of said mounting shank and extending in the X direction to a width four times the thickness of the metal, side flanges extending from said back web in the Y direction to a width between 4 and 8 times the thickness of the metal, said side flanges being doubled inwardly and back upon themselves and extending the full depth of said channel and up to the back web.

4. A contact element for electrical connectors, formed of a single piece of thin sheet metal, having an active portion at one end including a flexible contact blade, a terminal portion at the other end, and a mounting shank between said active portion and said terminal portion, and wherein, in tErms of rectangular coordinates, the major dimension of said contact may be defined as being in the Z axis, the long dimension of a cross-section of said blade adjacent to said mounting shank is in the X axis, the thickness of said cross-section of said blade is in the Y axis, and said blade is adapted to flex so that its elements move principally in the direction of the Y axis, said terminal portion being composed of four compactly-pressed laminations of said sheet metal, the two outer laminae being joined by a web integral therewith, perpendicular thereto and extending in the XZ plane, and the edges of the inner laminae adjacent to the web of said terminal portion being pressed into closely abutting relation thereto.