US3471677A - Interconnected aluminum and silver members and method of connecting the same or the like - Google Patents

Description

1969 c. R. DIXON 3,471,677

INTERCONNECTED ALUMINUM AND SILVER MEMBERS AND METHOD OF CONNECTING THE SAME OR THE LIKE Filed May 26. 1965 IN! 'ENTOR. CHARLES R. DIXON HIS ATTORNEYS United States Patent 3,471,677 INTERCONNECTED ALUMINUM AND SILVER MEMBERS AND METHOD OF CONNECTING THE SAME OR THE LH(E Charles R. Dixon, Henrico County, Va., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed May 26, 1965, Ser. No. 459,013 Int. Cl. B23k 11/16, 11/20 US. Cl. 219-118 12 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a method of joining an aluminum metallic member and a silver member together by disposing a first portion of a silver member against one side of an aluminum member so that a second portion of the silver member passes through an opening in the aluminum member and beyond the other side of the aluminum member to be secured thereto by a subsequent heating of the projecting part to form a eutectic bond between the second portion of the silver member and the other side of the aluminum member.

This invention relates to an improved product wherein a silver member is metallurgically interconnected to an aluminum member. This invention also relates to an improved method of metallurgically interconnecting together such members or the like.

It is well known that it is relatively difficult to metallurgically secure a silver member to an aluminum member because when a flux is utilized in the welding process, a corrosion problem exists because silver and aluminum in the presence of moisture are disastrously corrosive.

However, according to the teachings of this invention, an improved method has been found whereby a silver member can be readily joined to an aluminum member without the use of a flux or the like which would present a corrosion problem.

It has been found that such a method is particularly adaptable to provide a Switching arm for an air brake switching device or the like. However, it is to be understood that there are a great number of other uses of this invention.

For example, it is well known that certain air brake switching devices will have a switch arm which might be twelve feet or more or less in length and when normally formed of copper, the switch arms are too heavy for proper actuation thereof causing an uneconomical situation.

However, according to the teachings of this invention, the switch arm can be formed of light-weight aluminumcontaining material and can have silver contacts secured thereto according to the methods of this invention where by the silver contacts will provide the means for interconnecting the switch arm to the switch contact spring blades of the electrical switching device.

Accordingly, it is an object of this invention to provide metallurgically interconnected aluminum and silver members.

Another object of this invention is to provide an improved method of metallurgically interconnecting such members or the like.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings form ing a part thereof and wherein:

FIGURE 1 is a fragmentary cross-sectional view illustrating one of the initial steps for forming the improved structure of this invention.

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FIGURE 2 is a view similar to FIGURE 1 and illustrates the silver and aluminum members fully interconnected together according to the teachings of this invention.

FIGURE 3 is a fragmentary perspective view illustrating an electrical switch arm formed according to the teachings of this invention.

FIGURE 4 is a fragmentary cross-sectional view taken on line 44 of FIGURE 3.

FIGURE 5 is an end view of the structure illustrated in FIGURE 3 and illustrates the switch arm in another operating position thereof.

While the various features of this invention are hereinafter illustrated and described as providing an improved switch arm for an electrical switching device or the like, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide other structure as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the Wide variety of uses of this invention.

As illustrated in FIGURE 1, an aluminum-containing metallic member 10 is provided and has opposed surfaces 11 and 12. An opening 13 passes through the aluminum member 10.

A silver member 14 is provided and has a first portion 15 adapted to abut against the side 12 of the aluminum member 10 While a second portion 16 thereof passes through the opening 13 in the aluminum member 10 and projects beyond the side 11 thereof a suitable distance, the portion 16 being snugly fit in the opening 13 of the aluminum member 10.

Thereafter, the projecting part 17 of the portion 16 of the silver member 14 is sufficiently heated without flux to cause the same to form a eutectic bond 18 with the aluminum member 10 in the manner illustrated in FIGURE 2 whereby the eutectic bond 18 secures the portion 16 of the silver member 14 to the side 11 of the aluminum member 10 with the eutectic bond 18 extending into the opening 13 a substantial distance whereby the silver member 14 is securely fastened to the aluminum member 10.

In the embodiment illustrated in FIGURES 1 and 2, the silver member 14 comprises a of an inch silver brazier head rivet and the aluminum member 10 comprises a 0.235 of an inch thick aluminum alloy 6063 plate. About 0.163 of an inch of the portion 16 of the silver member 14 projects beyond the side 11 of the aluminum member 10 as represented by the reference numeral B.

A balanced wave tungsten arc welder 19, FIGURE 1, is utilized to supply the heat and the arc 20 was drawn to the silver rivet 14 until it is sutficiently heated to allow the silver to alloy with the aluminum to form the eutectic bond 18.

By using amperes for 40 to 45 seconds, it is possible to consistently make metallurgical joints between the silver members 14 and aluminum members 10 With the balanced wave tungsten arc welder 19.

The arc welder 19 comprises a tungsten heliarc whereby flux was not required, the are 20 being argon or argon and helium shielded in a conventional manner.

Thus, it can be seen that this invention provides not only an improved article wherein a pure silver member 14 is interconnected to an aluminum-containing metallic member 10, but also this invention provides an improved method of making such an improved article or the like.

For example, the structure and method of this invention as illustrated in FIGURES 1 and 2 can be utilized to make an electrical switching device as generally indicated by the reference numeral 21 in FIGURES 3 and 5.

As illustrated in FIGURES 3 and 5, the electrical switching device 21 includes a light-weight aluminumcontaining metallic hollow tubular member 22 suitably mounted for pivotal and rotational movement at the end 23 thereof and carrying pure silver contact members 24 on the end 25 thereof, the end 25 of the switch arm 22 being movable between a pair of spring switch blades 26 in a conventional manner and, thereafter, be rotated 90 in the manner illustrated in FIGURE to place the silver contacts 24 into electrical contact with the spring blades 26 to provide the electrical switching function in a conventional manner.

By forming the hollow tubular metallic member 22 with flat portions 27 as illustrated in FIGURES 2-4, the silver contact members 24 can be metallurgically bonded thereto according to the method of this invention by having a first portion 28 thereof disposed against the external side 29 of the aluminum member 22 and have a second portion 30 thereof projecting through an opening 31 in the wall of the tubular member 22 so as to project beyond the internal side 32 thereof and be bonded thereto by the eutectic bond 33 formed by the method illustrated in FIGURE 1.

If desired, first portions 15 and 28 of the silver members 14 and 24 can completely overlap the aluminum member or 22 around the openings 13 and 31 thereof as desired.

Thus, it can be seen that the structure and method of this invention can be readily utilized to provide an improved switch arm for an electrical switching device or the like wherein Weight problems are eliminated with out sacrifice of efficiency.

However, it is to be understood that the various features of this invention can be utilized to provide other articles as desired.

While reference has been previously made to a balanced wave tungsten arc welder for making the various joints of this invention, it is to be understood that an unbalanced wave machine could be utilized to form the joints of this invention.

In addition, it has been found according to the teachings of this invention that silver members of either pure silver or coined silver of about 1% inches long can be secured to aluminum members of alloy types 6063 and 6061 by the method of this invention with the resulting joints functioning in the manner previously described.

Accordingly, this invention not only provides metallurgically interconnected aluminum and silver members without the use of corrosive producing fluxes, but also this invention provides an improved method of metallurgically interconnecting such members.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be used, all coming within the scope of the claims which follow.

What is claimed is:

1. A method of joining an aluminum-containing onepiece, solid and homogeneous metallic member and a one-piece, solid and homogeneous silver member comprising the steps of forming an opening through said aluminum member, disposing a first portion of said silver member against one side of said aluminum member and a second portion of said silver member through said opening and beyond the other side of said aluminum member, applying an electric are against the end of said portion of said silver member which extends beyond the other side of said aluminum such that substantially all the are generated heat flows by conduction through said silver member to said aluminum member bringing each member to their eutectic temperature, thereby forming a eutectic bond between said second portion of said silver member and the other side of said aluminum member solely from the material of said silver member and said aluminum member whereby said members are fastened together, and removing said are when said eutectic temperature is reached.

2. A method as set forth in claim 1 and including the step of extending said eutectic bond into said opening.

3. A method as set forth in claim 1 and including the step of forming said silver member from pure silver.

4,. A method as set forth in claim 1 and including the step of snugly fitting said second portion of said silver member in said opening.

5. A method as set forth in claim 1 and including the step of completely overlapping said one side'of said aluminum member around said opening with said first portion of said silver member.

6. A method as set forth in claim 1 wherein said are is provided by a tungsten heliarc.

7. A method for making an electrical switching device comprising the steps of providing a hollow tubular aluminum-containing, one-piece, solid and homogeneous metallic switch arm, forming an opening through one wall of said switch arm, disposing a first portion of a onepiece, solid and homogeneous silver contact member against the external surface of said one wall and a second portion of said silver member through said opening and projecting beyond the internal side of said one Wall, applying an electric are against the end of said portion of said silver member which projects beyond the internal side of said one wall such that substantially all the are generated heat flows by conduction through said silver member to said one wall of said aluminum member bringing each member to their eutectic temperature, thereby forming a eutectic bond between said second portion of said silver member and said internal side of said one wall of said switch arm solely from the material of said silver member and said arm whereby said arm and contact member are secured together, and removing said arc when said eutectic temperature is reached.

8. A method as set forth in claim 7 and including the step of extending said eutectic bond into said opening.

9. A method as set forth in claim 7 and including the step of forming said silver member from pure silver.

10. A method as set forth in claim 7 and including the step of snugly fitting said second portion of said silver member into said opening.

11. A method as set forth in claim 7 and including the step of overlapping said external side of said one wall of said switch arm completely around said opening with said first portion of said silver member.

12. A method as set forth in claim 7 wherein said are is performed by a tungsten heliarc.

References Cited UNITED STATES PATENTS 3,015,022 12/1961 Bowers 219127 3,180,022 4/1965 Briggs et al. 29504 XR 3,299,240 1/ 1967 Foti 200-48 XR 3,310,388 3/1967 Bennett et al. 29504 XR 1,346,054 7/ 1920 Pennington 219-1505 3,243,561 3/1966 Foti 200-48 XR 1,296,651 3/ 1919 Gravell 219l50'.5 XR

FOREIGN PATENTS 12,984 10/ 1885 Great Britain.

JOSEPH V. TRUHE, Primary Examiner M. C. FLIESLER, Assistant Examiner US. 01. X.R. 219-117, 127

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