US1745721A - Bearing metal - Google Patents

Description

Patented Feb. 4, 1930 UNITED STATES PATENT OFFICE ROBERT JAY SHOEMAKER, OF CHTCAGO, ILLINOIS, ASSTGNOR T S. 80 T. METAL COM.- IPANY, OF GHICAGQILLINOIS, A CORPORATION OF ILLINOIS BEARING METAL 1T0 Drawing. Application filed September 16, 1927, Serial No. 220,062. Renewed November 8, 1929.

. This invention relates to the production of lead base alloys, and its object is to produce a lead alloy of such character that it may be used for bearings, bushings or other like ele- 5 ments where anti-friction surfaces are -required or for other purposes where a hardened lead is desirable. The invention has particularly in view the production of an anti friction metal which will be tough and relatively hard so as to be capable of sup porting heavy loads, and which at the same time possesses lubricating properties.

. A further object of. the invention is to provide an alloy of this character, the alloying metals of which will not dross or burn out, at least to any undesirable extent, either when the. ingredient metals are melted together in compounding the alloy, or when the alloy is" melted in casting operations.

A further object is toprovide an alloy of this character, which because of the character of its ingredients and its method of manufacture can be economically produced. The invention consists essentially in the use of a very small quantity of lithium as a hardening agent, sometimes in combination with a larger quantity of sodium, and the use with these materials of small quantities of calcium and aluminum to facilitate the combin'ation and to prevent drossing. Although lithium is a comparatively expensive metal, it has been discovered that the use of this metal in extremely small quantities (as little as .01 to 05%) will greatly increase the hardness'of the alloy and insuch small quantities this metal may be economically used. It is also effective in combination with sodium which is much cheaper and may be used in .comparatively larger quantities. The lead allo into which-these metals have been intro uced will be extremely unstable and the 'rare elements will burn or boil out, unless calcium and aluminum are'used as anti-drossing agents, the use of-both of these metals being practically necessary for reasons set forth hereinafter.

The following example will serve to illustrate the principles governing the compoundtug ofthis alloy. Modifications will be suggested and these modifications and all embodiments of the invention within the scope of the appended claims are intended to be Lithium 01% to 05% Sodium 2% to .8% I

Calcium ,1% to .7%

Aluminum 02% t0.1%

Tin 1% to 2% Leadito make up 100% The base metal is first produced by heating lead in a crucible to about 1600 Fahrenheit, the lead bath then being covered with calcium chloride or other suitable substance awhich will fuse and float on the molten metal without burning at the temperature specified. Metallic calcium is then stirred into the melt while covered with a supernatant covering of calcium chloride, which prevents the calcium from burning by exclusion of oxygen, The tin and aluminum are introduced in the same manner, the molten alloy thoroughly mixed, and then cast into ingots.

The ingots are then remelted to 650 to 700 Fahrenheit and the bath covered with, rosin or other neutral flux. The metallic sodium is then stirred in. The lithium is introduced as a lithium lead alloy, or in the form of metallic lithium. The lithium may I also be introduced by electrolizing a lithiumhalogen salt using molten lead as one electrode. The lithium is the primary hardening agent, and 05% or less of lithium will serve to increase the hardness of the alloy to from mm. A film of calcium hydroxide is formed on the molten alloy which serves to protect the rarer metals and hold them in the combination. The aluminum coacts with the calcium to keep 'down the amount of calcium,

which separates out and to minimizetjhe drossing loss of the other materials, particularly when the alloy is remelted. 7.

It seems that neither the calcium nor aluminum alone are'suflicient to ad uately prevent the loss of the lithium, but t at the two must be used together as specified, un-

less exceptional careis taken in preparing small quantities of the alloy at a time. The

use of. tin is optional but 'preferable,-and its v to introduce the use SBIVGS as an wa aluminum in the form 0 an aluminum-tin alloy.

- It has been foundthat alloys compounded substantially as hereinabove set forth are strong, tough and of adequate hardness, while still possessing all of the lubricating qualities of a good bearing 'metal. Since the lithium is used only very small quantities, the expense of the materials is not unduly increased, and

the combined use vof calcium and aluminum' as anti-drossing agents makes the alloy easy to compound and remelt without serious lossoi-the essential constituents.

Ic1aim:, l. A lead base alloy containing the followingimet'als in approxlmately the proportions, by weight, as follows: lithium .01 to .05%,

. sodium .2 to .8%, calcium .1 to .7 %,'tin 1 to 2%, aluminium .02 to .1% and lead to make up 100%.

2. A'lead'aglloy containing the following metals in approximately the proportions by weight as followszlithium .01% to 05%, I

sodium 2%. to .8%, calcium .1% to.7%, alumi- 1mm .02% to .1%, and lead to make up 100%.

. ROBERT JAY SHOEMAIQBR;