US1564335A - Fuse medium - Google Patents

Description

PATEN FHCE.

FREDERICK A. FELDKAMP, OF NEWARK, NEW JERSEY.

FUSE MEDIUM.

No Drawing.

T 0 all whom it may concern:

Be it known that I, FREDERICK A. FELD- KAMP, a citizen of the United States, residing at Newark, in the county of Essex and State of New Jerse have invented certain new and useful mprovements in Fuse Mediums; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings and to characters of reference marked thereon, which form a part of this specification.

This invention relates to improvements in electrical metallic fuse mediums; and the invention has reference, more particularly, to a novel composite metallic fuse material, consisting of a plurality of metallic elements, so related and combined as to provide a novel physical interrelation thereof forming an amorphous but united mass, adapted to be readily disintegrated under the influence of comparatively high temperature.

It is generally recognized that an ideal electrical fuse is one which would possess both high specific conductivity and low melting point. In the range of metallic materials suitable for use in an electrical fuse, it happens that metals having a hi h specific conductivity also possess a hig melting point; while metals having a low melting point ofier comparatively high resistance, i. e., possess low specific conductivity. If it is sought to provide the desired ideal characteristics of high specific conductivity and low melting point by forming an alloy of metal possessing one desired characteristic with a metal possessing the other de sired characteristic, the results obtained are not satisfactory, for the normal high specific conductivity of the one metal is reduced and the low melting point; of the other metal is increased in the resultant fusion or alloy of the two.

I have discovered that two metals, respectively possessing the desired characteristics of high specific conductivity and low melting point, may be combined to form a united or integral mass in such a manner that a maximum retention of the aforesaid desired characteristics is attained, and that consequently a highly efficient and compara tively ideal fuse medium is thereby pro vided. It is the object of this invention, therefore, to provide a composite metallic Application filed September 26, 1924.

Serial No. 740,104.

fuse material possessing comparatively high specific conductivit and low melting point in the form 'of a united or integral mass possessing cohesion and ductility, whereby the same may be cold rolled, drawn or machine worked to produce therefrom any desired shape or form of electrical fuse, but which, by reason of the novel physical relation of the metallic elements in physical combination, provides a mass which quickly disintegrates under the influence of comparatively high temperature.

In the subsequent detail description of my invention I have taken, for the purposes of illustrai ion, copper as the metallic element representative of the high conductivity class, and tin as the metallic element repre sentative of the low melting point class. In so doing, however, I do not intend to be understood as limiting my invention to the use of such particular metallic elements, since, 111 its broad aspects, my invention is intended to include any metals, or even alloys, in the respective classes, which are capable of being physically united or combined in the manner hereinafter set forth.

In producing my novel composite metallic fuse material, I take copper which has been reduced to a finely divided state, that is in the form of a powder or mass of small particles or granules. A suitable quantity of such finely divided copper is compressed into a block-like loosely adhering comparatively porous mass. The loosely adhering mass may then be immersed in suitable soldering flux, and thereupon dipped into molten tin or solder-like alloy. The molten tin or solder-like alloy will penetrate the interstices of the loosely adhering 'mass of copper particles, and will bond such copper particles together in a physically united integral mass. The surplus molten tin or solder-like alloy is drained away while the mass is hot, whereupon the mass may be submitted to pressure, at a suitable temperature, to further extrude surplus tin or solder-like alloy, while at the same time consolidating the resultant mass to desired density. The resultant mass is allowed to cool, thus forming What may be termed an ingot of my novel fuse material which may be worked cold by rolling, drawing, stamping or by suitable machine methods to produce any shape of finished electric fuse desired. It will be understood, that any other method found feasable to physically unite the metallic elements of my material may be employed.

In the novel material, obtained by the above described or any other suitable method, there is and should be a marked preponderance of the copper element, so that the relative quantity of tin is as small as possible; in fact, there should be, sub stantially, only that amount of tin present which is sufficient to bind the copper particles together. Fuses made from my novel composite metallic material will have a very high conductivity, as 80 per cent or more, as compared with copper fuses classified as 100 per cent, depending upon the relative quantity of the materials used, while at the same time I have retained, in such fuses, a low melting point equivalent to the melting point of tin alone (approximately 230 degrees 0.). These results are due to the fact that the metallic elements making up the novel fuse material, to wit, copper and tin, are merely mechanically combined, and are not alloyed or intermingled by fusion, or in any way chemically compounded, and, consequently, each metallic element retains its particular inherent and desired characteristics substantially unmodified; in other words, the copper remains pure copper and supplies a high specific conductivity characteristic to the fuse, and the tin or soldering alloy remains unmodified and supplies the desired low melting point characteristic.

It will be evident that the normal melting point of the material may be lowered or raised by employing metal or alloys, other than tin, which possess the melting point desired.

Besides the advantages of providing a comparatively high specific conductivity combined with a comparatively low melting pointZmy novel composite metallic fuse material, by reason of the character of the union efl'ected between the copper particles by the tin bond, provides a mass having what may be termed an amorphous internal or physical structure, as distinguished from a fibrous internal or physical structure such as would be possessed by copper alone or alloys of copper and low melting point metal. As a consequence of its amorphous internal or physical structure, when, in service, the temperature of the fuse is raised by the effects of abnormal overloads or short circuits and the fuse blows, the tendency of the material is to quickly disintegrate;

. that is, the low melting point metal quickly fuses or liquefies, thus eliminating the bond between the particles of copper, so that the latter drop away from the body of the fuse, thus quickly disintegrating the same, at the blowing point and quickly forming a circuit breaking gap, instead of forming an are requiring the consuming or vaporizing of the material until a gap of critical dimension is reached. This desirable disintegrating effect of my novel fuse material under comparatively high temperature, is quickly brought about for the reason that the incor porated particles of copper impart to the -material a high internal conductivity of heat, with the result, that on both sides of the breaking or blowing point of the fuse, the material is rapidly brought to the melting temperature of the binding metal, whereby gravity may act upon the freed particles of copper to cause the same to drop bodily away from the mass until a gap of critical dimensions is produced.

It will be understood that owing to the characteristic advantages of my novel fuse material above pointed out, it is possible to employ fuses of comparatively small mass according to the rating desired, and consequently such fuses will be more rapidly acting and safer than is the case with ordinary single metal or metallic alloy fuse links or members heretofore in use.

lVhile I have described above, as the two metallic elements combined to form my novel fuse material, other metallic combinations may be employed, viz, silver and tin (or lead and tin solder); aluminum and aluminum solder; or in fact any other combination of metallic elements may be employed to produce a product suitable for electric fuses and coming within my invention, so long as the two physically combined metals, one highly conductive and the other low melting do not unite as or form an alloy.

Ilaving thus described my invention, I claim 2- 1. A composite metallic fuse material consisting of a mass of metallic particles possessing relatively high 5 ecific conductivity bonded together by a lbw melting point metal.

2. A composite metallicfuse material comprisin a preponderance of a comminuted metallic element possessing relatively high specific conductivity formed into a mass with its particles adhesively connected by a relatively small proportion of a low melting point metal.

3. A fuse material comprising a mass of comminuted metal of -comparatively high specific conductivity, the particles of which are bonded together by a solder-like metal.

4. A fuse material comprising a mass of comminuted metal of comparatively high 6. A fuse material comprising granular metallic particles possessing relatively high specific conductivity compacted together and v interspersed with a metal of relatively low melting point which serves to bond the granular particles together.

7. A fuse material comprising a preponderanc'e of metal of relatively high specific conductivity in finely divided state combined with a comparatively small proportion of a low melting point solder-like metal. 8. A fuse material comprising a preponderance of metal of relatively high specific conductivity in finely divided state combined with a comparatively small proportion of a low melting point solder-like metal, the latter metal joining the particles of the former metal into a compact mass having an amorphous internal structure.

9. A fuse material comprising a relatively porous mass of copper containing tin in the interstices thereof.

In testimony, that I claim the invention set forth above I have hereunto set my hand this 24 day of September, 1924.

FREDERICK A. FELDKAMP.