US1071044A - Process of making bearing compositions. - Google Patents

Description

E. G. GILSON.

PROCESS OF MAKING BEARING COMPOSITIONS.

APPLICATION FILED JULY 7, 1910.

Patented Aug. 26, 1913.

i77eta/ ar 7d Graph/2e J. m; m mmwzw w fi 5 v WLH m e E W Witnesses:

UNITED srArEs, PATENT our-Ion- EMERY G. GILSON, OF SOHENECTADY, NEW YORK, ASSIGJWJB 'iQzGENEBAL ELECTRIC COMPANY, A CORPORATION OF'NEW'YOBK.

PROCESS OE MAKING BI EARING COMPOSITIONS;

" citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have in'ventedcertai'n new and useful Improvements in Processes of Making Bearing Compositions, of Which-the following is a specification.- t

My invention relates to the manufacture of metallic articles containing-a lubricating material, such as graphite, and which are suitable for uses requiring a mininium of; friction between rubbing or'slidingparts, such as brushes for dynamo-electric machines, dash-pots, bearings for shafts and the like.

In accordance with m invention, an h1- timate mixture of graph te anda-reducible metallic compound or compounds, for example, metallic oxids, is {heated to a temperature suflicient to redu ce allbut a small percentage of the oxids by interaction with some of the graphite. still containing a certain-percentageof unre duced material, is thencompressed into desired form and the reduction is continuedafter compression until it is substantially complete and consolidation of the metals has taken place. The presence of unreducedl material in the mixture beforecompression appears to prevent both segregation-- and'agglomeration of the metalpowder andresults in a homogeneous, strongproduct in which the graphite is distributed with great uniformity. Although appearing perfectly solid and dense, articles made by this process are still porous enough to-absorb considerable oil;

The accompanying drawin -*illustrates a dynamo-electric machine brus imadein accordance with my invention. 7

I will explain my invention-asapplied'tothe manufacture of metallic articles comsistingchiefly of copper associated with some metal or metals, whichwill alloywith copper, such as tin, lead or zinc, and in addition to these metals containing graphiteas alubricatingmaterial! metal is added to aid the consolidation'ot the copper particles by soldering-them togethen during the final stage 01" the-prccess-te-form The reduction mass,

"is-heatedand thetemperature to whieh;itis :withthe characterand f as shown inthedtiawin articlesare'then-packed 1ncharcoal; so asto/ lexclude air, and are again heatedtoatem iperature oft-650 to-700 O. untilthereduction 0f the metals is subaentially complete and lalloyage between the copper and tin,.,1ead; 011 other'metal has whom-place: To obtain ithese results, it is-ad visabl e-to regulate the heat andthe duration of heating-so as to; 95 reach the above temperature at the end oi -I about 18' hours, the heatingbeing then com The alloying Specification of Lctteu 2mm. p t tg ggg, 1 7 A iimm me new; mm mm no. 5mm.-

acoherent homogeneous mass, and it also acts as alubricant;

1 typical mixture, for exam le, consists -of-'100-part's of black copper OXld, GuO, 10 55- parts of-" tinoxid, SD02, and 125 parts of aphite. These materials, of course, should This mixture is'placed in a suitable retort,

.fconsisting for. example of copper, and is heated for about 8 hours to a tern erature 'of 650-to 700" G. At the endoifthis" time a large part of the metalswill' have been re- 56:1 .duced by the graphite to a metallic state ,butthe mixture shouldi contain small amounts of-unreduced oxide. of unreduced material will vary somewhat iwith the character ofthe mixture. mixes-need=containat this stage of'the pro- .fceedings no-more-than .5. to-2.5% of oXid but, 0 I

The amount course,- only relative-figures can be given. The-Isngth-of-timethat the-mixture subjected shouldbe varied. in accordance proportion of; the m xtnreand other conditions so as to leave 4 at least theabove amount" of 'unreduced oxid. For example, if lead'is: used-in addition tn 80 atin, the reduction temperature should not be .much more thanfiOW' G. andthe-ti'me should i be shortened.

Upon-cooling, themi'xture is put-through e109 mesh'sieve and is-compressed into prev as determined fOHIk-fbt example, the block" i The compressed tinnedfor about 60 hours; Iii'the finished.

article is to be used as a brush it: may then 7 be provided; witilsuitable current conned ,ti'ons 2:

As-an alternative method 0? obtaining the Some 70 thorough incorporation of the materials, a reducible salt, for example, copper acetate 1s dissolved in water .and the tin oxid and graphite are added to the solution. The solution is evaporated to dryness, the tinoxid and graphite beingmaintained uniformly distributed by constant stirring. The mass is then placed in a ball mill and .finely powdere The subsequent reduction is preferably carried out in a crucible which is provided with adasher .for the purpose of constantly agltating the materlal during the reductlon. The agitation in this case appears to be necessary to avoid agglomeration of the metal, The reduction takes place at a temperature ,in the neighborhood of 600 0., the range of temperature being somewhat lower than is the case when employing copper oxid. The reduction is continued for 21} to 3%hours, at the end of which time all 7 but about 5% of the tin oxid and co per oxid formed at this stage should have een reduced to the metallic state by,the graphite. The copper, of course, will not be present as acetate since the acetate is decomposable by heat and breaks down to form the'oxid. In this case, as well as in the alternative method of preparation described above,

the mixture will be spoiled by carrying, the reduction too far. In the latter method, however, the minimum amount of unreduced oxid permissible is in the neighborhood of 2 and as a rule 5% is preferable. After reduction the powder is put through a 100 mesh sieve and compressed into the -required form. The pressed blocks are finally heated for a long time in order to complete thereduction and agglomerate the particles in the manner described above.

These examples will serve to indicate the steps of the process, but it will, of course, be understood that the proportions will be varied in accordance with the properties desired in the finished article, the length of time required for reduction and the temperature' of the reduction being in turn varied somewhat in accordance with the materials used and their proportion, but in each case the conditions should be so regulated as to leave a small amount of unreduced metallic oxid in the reduction mix- ;ure before compressing the same into final orm.

Articles made by the above process are,

more or less porous and are capable of absorbing as high as 5% by weight of oil.

Whether any oil can. be introduced advan- It 1s to be understood that my invention applies to the manufacture of bearing ma terlal containing metalsother than those above specified. "Anymetal which has the requisite physical roperties and which can be .readily reduced: as, for example silver, can be used in place of copper. In the same manner other alloying'metals can be used, or they may be left out entirely.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. The process which consists in subject-- ing a mixture of reducible metallic compounds with a reducing material to a temperature sufiicient to reduce by the action of said reducing material all but a small percentage of said compounds to the metallic state, then compressmg the mixture in a predetermined shape and finally heatin at the reduction tem erature until the re uction is substantial complete.

2. The processwhich consists in subjecting a mixture of copper oxid, an oxid of metal alloyable with copper and graphite to a temperature at which reduction of said oxids by the graphite takes place and continuing thereduction until all but a small percentage of the metallic-constituents have been reduced, then compressing the mixture and continuing the reduction until said metals have beensubstantially completely about 600 to 700 C. a mixture of graphite.

copper oxid, and an oxid of a reducible metal capable of alloying with copper and continuing the reduction until all but a' small percentage of the metals have been reduced, then compressin the mixture and subsequently continuing t e reduction.

4;. The process which consists in subjecting a mixture of copper oxid, tin oxid and graphite to a tem erature of about 600 to 700 0., until all ut about .55% of said oxids have been reduced to the metallic state, then compressing the mixture and subsequently continuing the reduction until it is substantially complete.

5. The process which consists in subjecting a mixture of reducible metallic compound and a reducing agent to the temperature necessar to effect chemical reaction, agitatin t e material while reduction takes p ace,',molding the reduction mixture before the reduction is complete and then continuing the reduction until consolidation of the materials has taken place.

6. The process of making'a metal-graphits composition which consists in molding a mixture comprising copper, a soft metal 'alloyable with copper and reducible by carbon from its oxld, a small percentage of an oxidof at least one of said metals, and graphite in excess of the amount necessary to reduce said oxid, and heating m an inert environment until substantial reduction of molded mass with the exclusion of air until 10 the oxid and consolidation of the materials substantial reduction of the oxid and aghas taken place. glomeration and alloyage has taken place.

7. The process of making brushes for In witness whereof, I have hereunto set 5 dynamo electric machines which consists in my hand this 6th dafiof July 1910.

compressing a mixture comprising copper, E ERY GILSON. tin, about .5 to 5% of oxid of said metals, Witnesses: and graphite in excess of the amount neces- HELEN Onrono, sary to reduce said oxid, and firing the BENJAMIN B. HULL.

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