US1770688A - Molding material - Google Patents

Description

I Patented 15,. 1930 cLYnE 0. DE wrrr, or nouen'ron, mcmean momma Merriam 1V0 Drawing. Application filed April 8,

This invention relates to materials such as are .employed for making molds in which molten metal is to be cast, the principal bject being the revision of a synthetic mold- "5 ing material that will be efficient and satis-' factory in use, and economicalto.produce..

Another object is to provide .a synthetic molding material comprising a mixture of' sand and iron ore. Another object is to provide a molding material comprising a mixture of gel-coated sand and iron ore, the latter of which may also be provided with a gel-coating.

A further object is to provide a molding,

or core material comprising a mixture of sand and iron orewhich has-been treated with a. solution of iron hydrosol to provide the individual grains or particles thereof with a coating of iron hydrogel.

The material now universally used in making molds for the casting of molten metal is.

a sandfcla mixture known'as molding sand which is ound in the natural state in vanous parts of the countr These natural molding sands are found mbeds of varying thicknesses, and the clay, together with other material which forms the binder for the sand, varies in proportion from the top. to the bottom of the bed. Consequently some portions V of the bed may be too rich in binder, while other portions may be lean in binder. This condition as to-the 'whole bed may sometimes 'be remedied by thoroughly mixing all portions of the strata, but even in such cases the finalproduct may not be of the best qualityv desired and very often such mixture is not complete so that variousparts of the mass may havediiferent characteristics than other.

parts. Furthermore, in view of the fact that 49 the extent of such beds of natural molding sand is relatively limited throughout the country, this sand is relatively expensive and the freight charges necessary'to bring it from its point-of deposit to the foundry often run into a relative large fi re. Accordinglyi I have provide a synthetic molding materia which ma be-employed in the place-of n'a turaL mo ding sand; for substantially. all moldingoperations. j inaterial'is such as to be capableof being produced atarela- 1929. Serial No. 853,696.

bake the formed cores in order to provide them with the requisite rigidity. Further.- inore, these baked cores are not susceptible to the influence of water and consequently are relatively difiicultto remove from eastings having relatively complicated core work in them. The material provided by the present invention may be employed for cores without the addition of the so-called core oils or the subsequent baking operation, and may be readily and easily removed from the castings by simply flushing them out with water. The material I employ inthe presentcase is a mixture of sand and iron ore. The sand may be of a relatively varied nature. It may comprise sand of the natural molding type th t is deficient in natural binders, or it may be substantially naked sand, such as shore sand or any other sand that is suitably cleaned so as 'to remove any earth or any other foreign matter .that may be. mixed therewit in the-natural state. The iron'ore that I p fer to employ may be either hematite, or limonite, such. as is found in inexhaustible quantities in the natural state in various parts of the country. The size of the particlesof iron ore may vary according to the permeability desired in the final product, the greater the permeability the larger the particles of iron ore employed,jas will be readily understood to those skilled in the art.

' The sand and iron ore, either separately or mixed with each other, are subjected to a 9 solution of iron hydrosol so that each particle is provided with a coating'of iron hydro el'. The thickness of the coat maybe contro ed by the number of applications of iron hydrosol. If a relatively thick coatis desired the as particles may be dried or partially dried and then subjected again to the action ofthe .iron hydrosol and this-may be'repeated until the desired thickness of coat is acquired. If the send and ironlore are coatedseparately from each other, they must of course be thorou hly intermixedafter coatin e particles of iron ore an sand may be treated 'th the iron hydrosol in any desired manner, that is, the particles may be settled partially dried, formed into appropriate times wlthout further treatment with 11011 molds and used for the same purpose many hydrosol. When revivified by'the hydrosol treatment the coated sand and coated iron ore particles need not beseparated.

The stren h of any such mixture, moist or dry, de 11 s upon the contacting area be tween t e partlcles. The function of the hydro l in the moist state is to provide means of intimately contacting adjacent particles. Inthe moist state the strength is due mainly to the tensile strength of water at the contact points to thegrain packing and to the percentage of moisture. When the material is packed in the moist condition the i'llydlfi el ms ry their particles become both interlocked and cemented. The particles which have been separated in a dry state must of course be moistened and time must be allowed for the gelatinous coatin s to swell so that the coaescence 'of the lms will be accomplished agaln when the material is packed.

This material may be employed as a core sand without the addition of any core oils and without a baking process Used as a core and this material is quite hard when packed moist and air=dried, and is sufiiciently refracto for a number of foundry operations. After t e metal is cast around the core the removal of the core is accomplished by sim filiy vwetting the core material with .water.

mixture of the sand and "ironore may their be shaken out of the castin or more easily flushed out with a stream 0 water; In fact, if an air-dried or even a baked core of this I material is thrustinto a glass of water it will literally fly apart, dueeitherto the eagerness of its component materials to absorb water or to the capillary forces brought into play b presenting sma l orifices to the water, throug which the water rises into the ca illaries and disinte rates into its original small particles. 00

in doing so wets the particles orming the capillary walls to such an extent that the mass This c aracteristic ofthis material efiects a considerable saving in foundry practice.

The material herein specified will perhaps A be found more satisfactory for use in connection with metals having a relatively low meltmg point for the reason that if itis heated 1,77o,eea

on too hi h a temperature the mixture of iron oxide an silica tends to react to'form iron silicate. For metals having a relativel low casting temperature this objection has ittle, if any, application.

It is to be noted that any refractor material having a grain size similar to t at of sand may be use as described above in lace of the sand, and it is not my intention to imit the resent application solel to the use of sand and iron ore, and in the ollowing claims where the term sand is employed, it is to be understood as meaning not only sand as it is ordinarily known, but any refractory or like grain size that may be emplo ed in' its stead.

It may also be noted that ot er metallic hydrosols maybe employed in place of the iron, hydrosolt to impart a gelatinous coating to the grains of sand and iron ore and I, therefore, do not of iron hydrosol.

Where iron hydrosol is to be employed I prefer that it be emplo ed as a relatively cold solution having a p value of from 4.5 to 6.2 pH. The iron hydrosol solution may be prepared in the following manner. ,Allow a dilute solution of ferric chloride to dissolve all the hydrated iron oxide or ferric hydroxide that it can when the temperature of the solution is approximately to C. When properly prepared, such a solution will contain approximately one part of ferric chloride to fifteen arts iron oxide. The resultant colloidal so ution will be a clear, amber-colored liquid. The pH value of theiron h drosol may be adjusted by means of suita le neutralizing agents or bufi'ers, the function of which can be obtained from any textbook on physical or electro-chemist Other methods of preparing iron h drosol may be used-equall well, but lnasmuc as the present invention oes not relatfi to the preparation of the same, it is not t ought necessary to describe the same here.

Formal changes may be made in the cific embodiment of the invention descri without'de artingfrom the spirit and substance of t e broad invention, the scope of which is commensurate with the appended claims.

What I-claim is:

1. A material for making molds for metallic castings comprising a mixture of sand and iron ore.

2. A material for making molds for metalcastings comprising a mixture of sand and limit myself specifically to the use iron ore, said sand having an artificial coat- 3 ing of gel insoluble in water.

3. A material for making molds for metal lic castings comprising a mixture of sand and Iron ore, said sand having an artificial coatwith an artificial gel coating.

4. A material for making molds for metallic castings the bulk of which com rises a mixture of sand and iron ore the in 'vidual particles of which are provided with an alticial gel coating substantially insoluble in t water.

iron ore the particles of said sand ing provided with an artificial coating of iron hydrogel.-

8. An article of manufacture comprising a synthetic molding material composed of s ore sand and iron ore which have been treated with iron hydrosol. I

9. In the manufacture of an artificial molding material composed of particles of sand andiron ore, the step of subjecting said particles to the action of an iron hydrosol 'solution having a pH value of from 4.5 to 6.2.

' C; DE

ains and GERTlFICATE 'oF commc'ilou.

Patent No. 1,770,688.. Granted July l5, 19 30, to

' cums c. or WITTQ I t I It is her ebyrertlf ieri that error appears in the printed specification. of the above numbered patents'equiring correction as follows: PageZ. line 126, claim 7 3, strike out thewordswsaid sand haying an artificial coat and insert instead the, particles of which areproyided; and that the saidLetters Patent should be" .read with this correction therein that the same may conform to the record of thecase in the Patent Office. d g

' Signed and sealed this Z tth day of-February, A. 0.; 1931;

.M.J.Moore,' W

Acting Commissioner of Patents.