US3058091A - Sheet metal pin socket - Google Patents

Description

1962 H. E. HENSCHEN 3,058,091

SHEET METAL PIN SOCKET Filed June 4, 1959 5 Sheets-Sheet 1 INVENTOR. HOMER E. HE N BY 0W2), M I f/fi Oct. 9, 1962 H. E. HENSCHEN SHEET METAL PIN SOCKET 5 Sheets-Sheet 2 Filed June 4, 1959 Oct. 9, 1962 H. E. HENSCHEN 3,058,091

SHEET METAL PIN SOCKET Filed June 4, 1959 l 5 Sheets-Sheet 5 INVENTOR. HOMER E. HENSCHEN Oct. 9, 1962 Filed June 4, 1959 H. E. 'HENSCHEN SHEET METAL PIN SOCKET 5 Sheets-Sheet 4 0 M 6 l m I INVENTCSR.

HOMER. E. HENSCHEN Oct. 1952 H. E. HENSCHEN 3,058,091

SHEET METAL PIN SOCKET Filed June 4, 1959 '5 Sheets-Sheet 5- INVENTOR. HOMER E. HENSCHEN 21% M. JW

United States Patent 3,958,091 SHEET METAL PEN SUCKET Homer E. Henschen, Carlisle, Pa., assignor to AMP Incorporated, Harrisburg, Pa. Filed June 4, 1959, Ser. No. 818,115 7 Claims. Cl. 339-217) This invention relates to disengageable pin and socket type electrical connections.

Pin and socket connections of the type known to the art comprise a cylindrical pin which is secured, as by crimping, to a first wire and a socket having an axial bore which is secured to the second wire. Disengageable electrical connections of this type are widely used, particularly for relatively small wires, i.e. AWG 16 or smaller, and ofier the advantages of compactness and a high degree of reliability. Where a large number of electrical conductors must be disengageably connected, it is common practice to mount a plurality of electrical contact pins in one dielectric block and a corresponding number of sockets in a similar block so that by bringing together or separating the two blocks, the entire group of conductors can be connected and disconnected. These connector assemblies often contain as many as 50 or 100 pins and sockets to permit the disengageable connection of 50 or 100 conductors by the manipulation of only the two dielectric blocks in which the pins and sockets are mounted.

There are several structural and functional features which are common to practically all good quality pin and socket connectors and which are frequently required by the users of such connections. For example, it is desirable that the socket should have a closed entry, i.e. the entrance to the pin-receiving axial bore of the socket should be defined by a continuous rigid band of surrounding metal rather than by a split band. Where the socket has a closed entry, the possibility of damage, such as might result from the attempted insertion of an oversized test probe, is minimized and the life of the connection, in terms of the number of insertions and removals of the pin, is lengthened. It is also desirable that the force required to engage and disengage the pin and socket lie within relatively closely controlled and predetermined limits because, as explained above, pin and socket connector-s are often mounted in dielectric blocks with a relatively large number of pins and sockets in each block. Since the force required to engage and disengage these multiple connector blocks is largely determined by the engaging and disengaging force required for the individual pins and sockets, it follows that if this engaging force is high, the engaging and disengaging force required for the blocks will be extremely high and manual manipulation of the blocks may be impractical. Of course, it is also essential that the force exerted at the interface of the individual pins and sockets be adequate to establish a relatively low resistance electrical connection and since this contact force is dependent upon the engaging force, it follows that unduly low engaging forces can not be tolerated. Finally, it should be mentioned that since many pin and socket type connections are employed with relatively small wires and in circuits where compactness of design is of the highest importance, it is desirable to maintain minimum dimensions in the pins and sockets consistent with the attainment of the required physical and electrical properties.

Most of the commercially available pin and socket connectors are manufactured by machining barstock using conventional screw machine techniques which permit close dimensional tolerances and which therefore yield closely fitting pins and sockets. It is common practice to form the sockets by axially boring the barstock and cutting or milling a slot therein. For purposes of achieving the contact pressure between an inserted pin and the socket, a cantilever spring is secured to the socket in a manner such that it extends parallel to, and into, the slot so that the spring is resiliently stressed when the pin is inserted. U.S. Patent 2,716,744 shows one type of machined socket having a separate spring of this type for imposing the contact pressure between the pin and socket.

In general, these machined pin and socket connectors give good results and are highly satisfactory, however, they are relatively expensive as compared to connectors which are produced by die-stamping and die-forming of sheet metal stock. Furthermore, these machined pin and socket connectors cannot be manufactured in strip form, that is in the form of a continuous strip of connectors each joined to the other by the stock metal from which the strip was made. Connectors in strip form offer an advantage over loose-piece (i.e. individual) connectors in that a wide variety of crimping presses having feeding devices which automatically feed terminals in strip form is available so that the cost of applying a strip form connector onto a wire is usually less than the cost of applying a loose-piece connector.

It is an object of the present invention to provide an improved pin and socket electrical connecting device having a high degree of electrical and mechanical reliability. It is a further object to provide pin and socket type electrical connectors of a type which can be conveniently produced by conventional die stamping and forming methods from sheet metal strip. A further object is to provide a socket having an improved contact spring which is formed integrally with the socket at the time of manufacture thereby to avoid the problem of assembling a separate spring after manufacture. A further object is to provide an improved pin and socket connector which can be conveniently manufactured in strip form.

These and other objects are achieved in a preferred embodiment of the invention in which the socket member comprises a formed elongated strip of metal having a U-shaped portion at one end which is adapted to be crimped onto the end of a wire. The longitudinal edges of the remainder of the strip are bent relatively towards each other and joined together, as by welding or mechanical fastening, to form an axial pin-receiving socket. Contact pressure for an inserted pin is established by means of a spring finger which is integral with the socket member and which extends obliquely of the socket axis towards a slot in the socket. A tongue extends from the mouth of the socket and is reversely bent rearwardly over this finger and then obliquely away from the socket. This tongue serves the dual function of retaining the socket against axial movement in a dielectric block and also on its underside serves as a bearing surface and support for the end portion of the spring finger. By virtue of this arrangement, when the pin is inserted the finger is loaded and is stressed in the manner of a cantilever beam which is supported against lateral movement at its free end. The pin member in accordance with the preferred embodiment is formed in substantially the same manner as the socket, that is by bending the longitudinal edges of a metal strip towards each other. The nose portion of this pin, which functions as the electrical contacting portion, is rolled into the form of a cylinder and an intermediate portion is provided from which is struck a finger similar to the contact spring finger of the socket. This finger on the pin, however, functions as a retainer to lock the pin in a dielectric block.

In the drawings:

FIGURE 1 is a perspective view of a socket member in accordance with the invention;

FIGURE 2 is a side view of the socket member of FIGURE 1;

FIGURE 3 is a view similar to FIGURE 2 but showing the socket member positioned in a dielectric block and illustrating the function of the retaining spring;

FIGURE 4 is a view similar to FIGURE 3 but showing the positions of the parts when a mating pin is inserted into the socket;

FIGURE 5 is a cross sectional view showing a complete pin and socket set with the parts in engagement with each other;

FIGURE 6 is a side view of a connector pin member in accordance with the invention;

FIGURE 7 is a plan view illustrating the sheet metal blank from which the socket member of FIGURE 1 is formed;

FIGURE 8 is a plan view of the sheet metal blank from which the pin member of FIGURE 6 is formed;

FIGURE 9 is a perspective view of a dielectric block having openings to receive pins or sockets in accordance with the invention;

FIGURE 10 is a perspective cut away view of a portion of a dielectric block showing the form of the openings;

FIGURE ll is a view taken along the line 11--11 of FIGURE 5; and

FIGURE 12 is a perspective view of a stamping and forming progression showing the manner in which the socket members in strip form are manufactured.

Referring now to FIGURES l5 a socket member 2 has at one end thereof an insulation crimp portion 4 and a wire crimp portion 6. When the socket is secured to a wire, the sidewalls of these crimp portions are bent relatively towards each other and then towards the insulation and the strands of the electrical conductor to establish an electrical and mechanical connection therewith. A web 8 extends along the top of the socket, as viewed in FIGURE 1, and sidewalls 10 extend from the sides of this web downwardly. These sidewalls curve towards each other in their lower portions and their edges 12 are bent outwardly so that their internal surfaces are in abutting relationship and are welded as shown at 14 to form a stiffening rib which extends axially along the socket. Sidewalls 10 thus define a pin-receiving axial cavity which is semi-cylindrical in its lower portions, as viewed in FIGURE 1, but which has substantially parallel and straight sidewalls in its upper portions adjacent the web. It will be noted in FIGURE 11 that the radius R of the semi-cylindrical portion is substantially equal to the distance from the web to the center of the semi-cylindrical portion so that a substantially cylindrical pin can be inserted into the cavity. The rib formed by the edges 12 has an extension 16 adjacent crimped portion 6 which functions as a stop when the socket is inserted into a dielectric block.

A resilient finger 18 is formed from the intermediate section of web 8 by severing this web from the sidewalls along its longitudinal edges and severing along a line extending transversely across the web adjacent the open pin-receiving end of the socket. Advantageously, this finger, which functions as a contact spring, does not extend entirely up to and against the front portion 9 of the web but a short section of the web is punched out during the forming so that an appreciable gap is left between the front end 22 of the finger and the web portion 9. Intermediate its ends this finger is bent downwardly at 19 and into the cavity in the socket while its extreme end 22 is reversely bent so that it extends outwardly beyond the socket.

On each side of finger 18, sidewalls 10 are cut away as shown at 24 and the edge portions of the sidewalls are bent outwardly to form stabilizing flanges 26. A tongue 28 is integral with the web at the frontal portion thereof and is reversely bent at 30 so that it extends rearwardly towards the crimped portion of the socket as shown in FIGURE 2. At the end 22 of finger ;18, this tongue slopes downwardly towards the axis of the socket and then obliquely away from the axis of the socket. While the end 22 of the finger and the portion 32 of the tongue may normally be in contact with each other, as shown in FIGURE 2, as a general rule, neither of these parts is stressed to any appreciable extent by the other when the end of tongue 23 is free as shown in FIGURE 2. In other words, the finger is substantially in its normal position as shown in FIGURE 2.

Referring now to FIGURES 3, 4, 9 and 10 a preferred type of dielectric block 34 has parallel faces 35, 37 and a plurality of cavities 36 each of which is shaped to receive a socket or a pin as described below. Thus, each cavity has a rearward section opening into face 37 (FIG- URE 10) of substantially circular cross section excepting for a fiat wall 38, an intermediate section of which slopes obliquely towards the axis of the opening. A frusto-conical transition section 44 is provided intermediate the ends of the cavity and extends about halfway around the cavity wall opposite fiat wall 38. This flat wall ends at an abrupt shoulder 40 which is disposed on the rearward side of frusto-conical surface 44. The right hand portion of the cavity as viewed in FIGURES 3 and 11 is of substantially uniform cross section throughout its length and has a semi-cylindrical wall 52 adjoining the frusto-conical surface and a pair of diametrically opposed ledges 42 on each side of wall section 52. A pair of flat parallel sidewalls 48 extend from these ledges to a flat wall 46 which extends from shoulder 40. As shown best in FIGURE 10, sidewalls 48 extend rearwardly beyond shoulder 40 and then diverge at 49 to define a guide section which aligns the socket during insertion.

As shown in FIGURE 9, block 34 may provide extension 39 on its sides having openings 41 for the reception of a suitable means for securing two blocks together and/or for polarizing the two blocks to ensure that they are assembled to each other in proper orientation. For example, it is known to provide pins in some of these openings to ensure polarization and machine screws and nuts to clamp a pair of blocks together. It will be understood that blocks of the type shown usually are provided with a metallic housing, the block 34 having a shoulder 43 for cooperation with such a housing.

To assemble the socket 2 to the dielectric block, it is merely necessary to insert the socket from the left as viewed in FIGURE 3 thereby to compress tongue 28 until it passes beyond shoulder 40 at which point rib extension 16 engages the frusto-conical surface 44. The socket can not be inserted beyond the position shown in FIGURE 3 by reason of the presence of this surface and it cannot be withdrawn from the opening since it is held in place by the end of tongue 28. Where removal of the socket is necessary, it can be accomplished by merely inserting a narrow blade from the right in FIGURE 3 against the upper surface of tongue 28 to depress this tongue and permit it to clear shoulder 40.

When a connector pin 54 of the appropriate size is inserted axially into the cavity as shown in FIGURE 4, the rounded nose portion of this pin engages the underside of finger 18 and pushes it relatively upwardly, insofar as is permitted by tongue 28, so that the profile of this finger changes from that of FIGURE 3 to the profile substantially as shown in FIGURE 4. Essentially, this finger can be considered to be a cantilever beam extending from the body of the connector socket and having its free end 22 supported against substantial radial movement away from the axis of the socket. Some radial movement of this free end may take place but such movement will be limited by the underside of the tongue. The free end is, however, free to move axially, relative to the socket axis, over the underside of tongue 28. The amount of such movement will be relatively slight; however, the fact that this end is free to move is an important factor in maintaining reproducibility of the insertion and extraction force for the pin.

Turning now to FIGURE 6, there is shown a connector pin in accordance with the invention which is also formed from sheet metal in the same manner as the socket. The connector pin comprises a cylindrical contact nose portion 54 at one end which is adapted to enter the socket cavity, a frusto-conical transition section 58, and an intermediate portion 59 which has a cross-sectional configuration similar to the intermediate section of the socket. Thus, this intermediate section has a substantially fiat web 62 from which parallel sidewalls eX- tend adjacent thereto and the sidewalls in turn are curved towards each other and their edges are outwardly bent at 60 and welded together to form a longitudinal stiffening rib. As with the socket, this rib is enlarged as shown at 61 to form a stop for the purpose of locating the pin in a dielectric block. This intermediate section also provides laterally extending stabilizing fins 64 on each side of the web and the web itself is severed along its edges and bent outwardly as shown at 66 to form a resilient finger. This finger functions as a retaining spring for retaining the pin in the dielectric block cavity and, like the corresponding tongue 28 of the socket, it extends rearwardly towards the crimped portion in order to serve this function. Thus the pin of FIGURE 6 differs from the socket in that the retaining spring 66- in the pin is formed from the web while in the socket the retaining spring is formed by means of the tongue which before bending extends axially in front of the socket. The lefthand portion of the pin as viewed in FIGURE 6 comprises a wire crimp portion 68 of U-shaped cross section having a flat web as with the socket and an insulation support crimp portion 70 having a similar cross sectional configuration. These U-shaped ferrule forming portions are crimped onto the end of a wire in the same manner as the corresponding portions of the socket. It will be apparent from the drawing that the intermediate and lefthand end portions (the ends which are secured to the wires) of the socket and of the pin are similar in shape and dimension. By virtue of this similarity, the dielectric block 34 can accommodate either pins or sockets and this is an advantageous feature of the invention in that the number of dif ferent parts (i.e. pins, sockets dielectric blocks) which are required for a multiple connector assembly is thereby reduced.

FIGURES 7 and 8 show the punched out sheet metal blanks from which sockets and pins in accordance with the invention are formed. The structural features of these blanks are identified by the same reference numerals as those used in FIGURES 1-6 in the foregoing description of the finished parts, the reference numerals of FIG- URES 7 and 8 being differentiated by prime marks in the interest of clarity. Referring to FIGURE 12, it will be seen that in the preferred method of forming sockets in accordance with the invention, the blanks are stamped from strip metal in side-by-side parallel relationship to each other 'with each blank connected by means of a slug or connecting piece 72 to a carrier strip 74 having evenly spaced perforations 7 6 therein to facilitate feeding of the strip to an automatic crimping machine. During the successive forming steps for the socket, the blank is cut to form the finger 18, the finger is bent, the sidewalls are progressively curled upwardly, and the tongue 28 is bent downwardly and rearwardly. The blank for the pin member can be formed in substantially the same manner as is shown in FIGURE 12 excepting that the foreward extension (56' in FIGURE 8) is rolled about the longitudinal axis of the blank to form the cylindrical contact nose of the pin. Advantageously, the end of this extension is scalloped so that a substantially hemispherical leading end on this contact nose results.

A salient overall advantage of the invention is that it permits the manufacture of pin and socket type connectors by die stamping of sheet metal and connectors manufactured in this manner can be produced more cheaply than by automatic screw machine methods. Furthermore, as previously noted, stamped sheet metal connectors can be produced in strip form and strip form connectors can usually be applied to wires more easily than loose-piece connectors by reason of the fact that strip connectors can be automatically fed to the crimping tool or press with relative ease. However, for a thorough understanding of the instant invention, there is presented below a discussion of some limitations of die stamping processes and a discussion of some of the structural features of connectors in accordance with the invention which permit the manufacture of pin and socket nectors by die stamping notwithstanding these limitations.

In general, where metal articles are manufactured by stamping and forming sheet metal, it is recognized that the dimensional tolerances obtainable are not as close as the tolerances which are obtainable in machining operations such as are performed in the manufacture of parts by an automatic screw machine. -It is also recognized in the die stamping art that when sheet metal is bent to form a part of a particular shape, the metal tends to spring back to some extent after the work is removed from the bending die. The tendency of the bent metal to spring back usually cannot be completely overcome and it is common practice, where a bending operation is to be performed, to bend the metal to a greater degree than is required in the finished part so that when the metal springs back the part will have the desired configuration after it is removed from the die. The phenomenon of spring back, it might be mentioned, is a result of the elasticity which remains in a deformed piece of metal after the yield point has been passed. While spring back can be controlled to some extent by over bending, it is difiicult to control within precise limits.

Considering now some features of the connectors, it will be apparent that the dimensional tolerances of a pin and socket must be such that the parts will be engageable and disengageable with relative ease. At the same time, the fit of the pin in the socket must be sufficiently snug and the force exerted at the pin-socket interface must be sufficiently high to establish a low resistance electrical connection. In some known types of connections, this problem ofobtaining adequate forces at the pin-socket interface (i.e. adequate pressures) for a good electrical connection without an unduly high insertion force for the pin have been achieved by providing a cantilever spring on the socket which is flexed by the pin upon insert-ion thereof. These cantilever contact springs must be designed such that they will withstand the deflection to which they will be subjected upon insertion of the pin without the imposition of stresses higher than the yield point of the material. For example, where the contact portion of the pin has a diameter of about 0.050 inch, as a practical matter, the contact spring should be capable of deflecting about 0.004 inch without exceeding its yield point and the contact spring should impose the desired contact pressure on the pin when it is deflected by this amount. It would be impractical to design the spring for a deflection of less than about 0.004 inch for a 0.050 inch diameter pin by reason of the tolerances in the pin diameter for which allowances must be made.

In most known connectors which have such cantilever springs, the spring has been provided as a separate piece which is asembled to the connector by clinching or some similar securing method. This scheme of having the spring as a separate piece has a distinct advantage in that the spring can be made of a metal having better spring properties than the connector itself. To illustrate, brass or phosphor bronze are excellent metals for the socket itself since they are easily formed, have sufficiently good electrical conductivity and strength and can be crimped onto wire ends with relative ease. However, these metals are not desirable spring materials for the cantilever springs of sockets of the instant type by reason of the fact that their yield strengths are not sufliciently high. The yield strength of phosphor bronze is about 75,000 p.s.i. While the yield strength of a hardened brass is about 62,000 p.s.i. It would be impractical and difficult to design a simple cantilever spring of relatively thin sheet using these materials which would satisfy the performance requirements of cantilever springs for sockets of the instant type. Reference is made to US. Patent to Swanson No. 2,716,744 for a teaching that it is desirable to make these springs from a relatively high yield point material such as berylium copper or Inconel (an 80% Ni, Fe, Cr alloy).

-In the present invention, the spring may be formed of a material having a relatively lower yield strength than in these prior art devices by reason of the fact that this spring is a supported cantilever rather than a simple cantilever. The end of the spring normally bears against the underside of the tongue or is positioned very close to this tongue and this end is, moreover free to move longitudinally relative to the surface of the tongue. Thus, when the pin is inserted, the contact spring is flexed in the manner of a cantilever beam which is freely supported at its end. Recourse to beam stress formulae will show that a supported cantilever beam of a given length and cross section will withstand a considerably higher load without exceeding its yield point than will a similar beam without end support. The beam load in the instant invention is, of course, the load imposed by a pin and the reaction forces imposed by the spring on the pin to establish the electrical connection.

A mathematical analysis of an unsupported cantilever beam will show the following relations: For a simple cantilever beam where For a supported cantilever beam, and assuming the load is applied at a point 0.61 I from the fixed end, the load P is as follows:

s bi (H) 10241 The ratio of these loads 1 B PA is then 5.75 so that (III) P =5.75 P

Thus a supported cantilever beam of a given material and given dimensions will withstand a load 5.75 times greater than an identical unsupported beam assuming that the unsupported beam is loaded at its end and the supported beam is loaded at 0.61 I.

It will be noted from Formula I that P will increase as the length l of the beam is reduced and it might seem that a simple cantilever beam of extremely short length might be employed in order to develop the required contact pressure P However, as the length of the beam is reduced, its maximum deflection at its end is also reduced and, as pointed out above, the contact spring must be capable of some minimum deflection as a practical matter to allow for manufacturing tolerances and variations. Therefore, it would not be a satisfactory solution to reduce the lengths of the contact spring in order to obtain the required contact pressure.

The foregoing discussion is not intended to limit the inventions to the assumptions made or to the formulae presented since these formulae are merely expressions of 8 the relationships which exist for a particular embodiment of the invention. Where the supported cantilever contact spring is loaded at a point other than 0.61 I, the exact ratios presented will not obtain. This discussion is merely presented then to show the advantages in a specific case.

It is not intended to imply that the tongue is completely rigid in the disclosed embodiment. As shown in the drawings, upon insertion of the pin some fiexurc will be imparted to the tongue via the end of the contact spring. However, the end of the contact spring is not free to move radially and since its radial movement is substantially limited, it is stressed in the manner of a supported cantilever in the disclosed embodiment. In some instances it may prove practicable to have a com pletely rigid support, such as the wall of the dielectric lock, for the contact spring.

Turning now to the problem of spring back with reference to the disclosed embodiment, it will be recalled that the dielectric block is advantageously of molded phenolic or other plastic. Molded plastic parts can be made to very close dimensional tolerances with ease and the dimensions of the openings in the block are, in the disclosed embodiment, held Within precisely predetermined limits. When the socket is inserted into the opening, the end of the tongue is flexed towards the socket axis as shown in FIGURES 3 and 4 so that after insertion, this tongue occupies a precisely predetermined position with relation to the location of the contact spring.

From the foregoing it will be apparent that the precise dimensions of the openings in the block are utilized as a means for compensating for any lack of precision in the position of the tongue. This means that the exact location of the tongue, as fixed in the bending die during manufacture of the socket, is not of paramount importance and the problem of bending this tongue in a precise and exacting manner is obviated. Of course, as explained above, precise bending of the tongue would be difficult because of the spring back of the metal.

Another advantageous feature of the invention is that since the contact spring is integral with the connector (i.e. formed to the same strip) the contact surface between the spring and the pin is fully effective as an electrically conducting interface. Where, as in the prior art, the spring is a separate piece, its contact with the tongue is not fully effective because an additional interface, or electrical barrier, is presented Where the contact spring is mechanically secured to the socket.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

I claim:

1. A sheet metal electrical connecting device formed from an elongated strip having an end portion of U-shaped cross section crimpable onto a conductor and a tubular adjoining portion, the longitudinal edges of said strip in said tubular adjoining portion being radially outwardly bent and secured together to form an axially extending rib, said rib being of stepped profile to form a stop intermediate its ends for engagement with a portion of a housing member into which said connecting device is adapted to be inserted, a spring extending lengthwise of said connector struck out from said tubular adjoining portion on the opposite side from said rib, and longitudinal stabilizing ears on each side of said spring, said ears comprising outwardly bent portions of said strip adjacent to said spring, said ears being adapted to engage complementary surfaces in said housing thereby to prevent movement of said connecting device.

2. A device as set forth in claim 1 wherein said tubular adjoining portion comprises a socket for reception of a pin, said spring comprising a contact spring for engagement with said pin upon insertion thereof.

3. A device as set forth in claim 1 wherein said tubular adjoining portion comprises a socket for reception of a pin, said spring comprising a contact spring for engagement with said pin, said spring extending towards the open pin receiving end of said socket and having an intermediate incurvate portion extending into the interior of said tubular portion whereby said spring is displaced relatively outwardly of said socket by said pin.

4. A device as set forth in claim 1 wherein said tubular adjoining portion comprises a socket for reception of a pin, said spring comprising a contact spring for engagement with said pin, a tongue extending from the open end of said tubular portion rearwardly of said tubular portion and past said spring, said tongue being adapted to engage a shoulder in said housing member to prevent withdrawal of said connecting device therefrom, and said tongue functioning as a support for the end of said spring upon insertion of said pin.

5. A device as set forth in claim 1 including a cylindrical pin portion extending from said tubular portion, said spring extending towards said U-shaped section and obliquely away from the axis of said tubular portion whereby, said spring functions as a retainer spring to prevent withdrawal of said connecting device from said housing.

6. A sheet metal electrical connecting device formed from an elongated strip having an end portion of U-shaped cross section crimpable onto a conductor and a tubular adjoining portion, said tubular portion comprising a socket adapted to receive a pin, the longitudinal edges of said strip in said tubular portion being radially outwardly bent and secured together to form an axially extending rib, said rib being of stepped profile to form a stop intermediate its ends for engagement with a portion of a housing member into which said connecting device is adapted to be inserted, a spring extending lengthwise of said tubular portion towards the pin-receiving end thereof, said spring having an intermediate incurvate portion extending into the interior of said tubular portion whereby said spring imposes a contact pressure on said pin, a tongue extending from the open end of said tubular portion rearwardly thereof and past said spring, said tongue being adapted to engage a shoulder in said housing member to prevent withdrawal of said connecting device therefrom, said tongue functioning as a support for the end of said spring upon insertion of said pin, and longitudinal stabilizing ears on each side of said spring, said ears comprising outwardly bent portions of said strip adjacent to said spring, said ears being adapted to engage complementary surfaces in said housing thereby to prevent movement of said connecting device.

7. A sheet metal electrical connecting device formed from an elongated strip, said connecting device comprising a cylindrical tubular portion adapted to receive a pin, a spring struck out from said tubular portion and extending lengthwise thereof, said spring having an intermediate incurvate portion extending into the interior of said tubular portion whereby said spring imposes a contact pressure on said pin, a tongue extending from the open end of said tubular portion rearwardly thereof and past said spring, said tongue being adapted to engage a shoulder in a housing member into which said device is adapted to be inserted thereby to prevent withdrawal of said device from said housing, an intermediate portion of said tongue functioning as a support for the end of said spring, and longitudinal stabilizing ears on each side of said spring, said ears comprising outwardly bent portions of said strip adjacent to said spring, said ears being adapted to engage complementary surfaces in said housing thereby to prevent movement of said connecting device.

References Cited in the file of this patent UNITED STATES PATENTS 2,310,142 Woodman Feb. 2, 1943 2,701,350 Soreng Feb. 1, 1955 2,738,485 Batcheller Mar. 13, 1956 2,794,963 Hess et a1 June 4, 1957 2,813,257 Cornell Nov. 12, 1957 2,888,662 Hammell May 26, 1959 FOREIGN PATENTS 1,188,936 France Mar. 16, 1959

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