US1614659A - Foundry sand - Google Patents

Description

mama Ja'nf18, 1927.; f

WILLIAJ; CURETON; DF'CHICAGO. ILLINOIS.

FOUNDRY SAND.

No Drawing.

The invention pertains to theart of-molding as practiced in foundries in connection. with the production ofcastings .from vari ous kinds of metals, and has particular reference to the composition of the foundry sand from which the molds are made.

In-oonstructing molds for gray-iron, malleable iron,.andnonferrous metal castings, the rgenerah-practice heretofore has been to use; a foundry sand 5 which. is composed of a mixture of silica sand, some clayey material containing principally alumina. lime.

magnesia and iron compounds to.giv e the neeessar bondin ualitv and some sea coalorother carbon material to give the necessary refractory quality, to all of which a suitable quantity of water is added ,and thoroughlyz-mixed, The bonding and refractory qualitiesotIthi-s foundry sand are not very high, however-rand under-some conditions of..use: it .is-,-usual to increase the. same, the-bonding quality by the addition of flour, pitch compounds; or other organic resinous=substancesrand the refractory (pull ity by. the facing of the molds with =grap rite, or other. high carbon compounds. In constructing nolds. for steel castings, the practice has been to use ais'omewhat similar foundry.sand-. which is-composed of a purer silicasand, some. finely ground fireclay and pitch, ancLsome molasses or other organic resinous compounds vmixedwith water.

Th e foundry sands above. dcscri bed have been widely used for years, but such sands have :many 5 objectionable eharm-teristies which are reflected disadvantageously in the appearance, surface texture-and average cost of the satisfactory castings produced. 'lhe sands will: stick to the patterns unless 'inoistoned with great uniformity, and will pack too :hard to allow the gases to escape: if too muclrnioisture-is used. l urthermore, the sands-"will fuse in contact with the molten metal,irrespective ofqthc skill' with which the-sands are prepared, and such fusing-or, burning of the sands will form gases ands'lag,-w11l render the surfaces of the castings irregular, and will lower the bonding and refractory qualities of the sends to such an extent as to make a substantial portion of the same unfit for subsequent use.

The object of the present invention is. to provide an inexpensive foundry sand which is not open to any of the objections above described.

The foundry sand of the invention con- Application filed April e, 1925. Serial No. 21.121.

- sistsessent ally of a base of silica sand and a. binder of :1V finely ground mineral commercially-known as-talc, to which mixture lsadded sufficient .waterto moisten the same properly. The novel and highly advantageousemployment of tale in this association isrthe salient feature of the invention. T 1110 has .a. lubricating or.soapy feel ng to the fingers, is soft, andmay be easily ground to an impalpable. powder having 'aplast c quality soineyvhatsiinilar tothat found in' clays. Taleis ehenncally known as magnesiumsilicate, (Si() but one form is an aluminun vsileateknown. as pyrophyllite,.H OALQQfl-SiQ While-some .de )osits of themineral-talc cannot be used,-pro ably because (if such impuritiestherein as iron.

lime and;.-L'layey" materials wrhich tend to form gases iand .slag.- nfthe molds, certain (leposits-{found 1-. to sutiiciently pure for the purpose have beenanalyzed-with the followinggresultsr ISilicon 60.2%, magnesia.

' 30.33%, iron oxides and'alumina 3.8%; combi ned water,

5.35%,lime 0.9%, and moisture 0.3%.; The-silica;- sand and-the talc may be combined in -a wide; range "of 'propo'rtions dcpending. I of course.,. upon the particular type of casting: for"-ivhich.the. sand isto be used, the-amount of talc=being increased asa general rulerin proportion to the amount of silica sand. as alnghenbinding quality is required of thesand .Oiieproportloning of the constituent materials of the foundry-sand, \vhieh has been founcl-togive very. good results for one typeof; casting, is about four parts of silicapsandto;aboutoneparboftalc. It will be. understood? however that this particular ratiois referred to-smei ely for the, purpose of exemplification, and is notto be construed in any way: asragrestr-ictionof thespirit of the .i nvention I such definite'; purposes.

\Vherc a very high degreejof fineness is' desirable in the foundry sand. asis the case inthe;production-20f{certain typ s-of castings, the sandtmay. contain, inaddition to the silica-sandand: the. tale, some :ground silica known as filica ;-mesh='orfflint. The amount of flint-used,"in proportion. to the other constituent materials,de nds in large measure upon .theifin'eness'o' the material.

The foundry sand oitheinvention is dis tinctlysu rior.in' a number of ways over .thesands eretofore used in foundries. The

silica sand an the tale, when combined in suitable proportions, form an eflicient bond.

out material loss in bulk or quality, it being only necessary to add small amounts of talc from time to time to maintain the bonding quality in the sand. Due to the soapy characteristic of the tale in the sand, the patterns ma be Withdrawn from the molds with ease an will leave a very accurate impression. This advantage is particularly evident when thezmolds are made with the various types of molding machines now in use. Furthermore, when the molds are rammed hard the sand will still retain its porosity, and excessive moisture will not accumulate in-spots, as so oftenhappens in molds made with other kinds-of'foundry sand. Because of the nature of the sand the moisture may be readily mixed and blended throughout the mass The foregoing advantages are but a few of those possessedby'the foundry sand 1' .of the'invention, and other advantages will be at. once evident to those skilledin the art upon use of the sand.

I claim: a

L'A foundry sand composed of a material and a binder of tale.

2. A. foundr sand composed of a base of silica sand an a binder of talc. 3. A foundry sand composed of a relatively large portion of silica sand and a relativel small portion of talc.

4. A oundry sand composed of a base of silica sand and a binder of finely ground talc combined in the approximate proportions of about four parts of silica'sand and one part of talc.

5. A foundry sand composed of a base material, talc, and ground silica.

6. A foundry sand composed of silica sand,'ta1c, and flint. 4

7. The method of preparing foundry sand base for castings which consists in'binding the base material of the; sand throughout its mass with talc. I p

8. The method of preparing foundry sand for castings which consists in binding a. base of silica sand throughout its mass with a binder of finely ground talc.

In testimony whereof I have hereunto subscribed 'my name.

' WILLIAM CURETON.