US1845371A - Foundry facing and method of applying same to molds - Google Patents

Description

Patented Feb. 16, 1932 PATENT OFFICE I -BENJ'AMIN WALLAGE,.OF BROOKLYN, NEW YORK 0UNDRY FACING AND METHOD OF APPLYING SAME TO HOLDS Ito Drawing.

This invention relates to the casting of metal'in sand molds, more especially iron, and has for its particular objects the provi- SlOIl of a facing material that is peculiarly 5' adapted for spraying or atomizing upon the lfi ing sand layer can be readily peeled without resorting to laborious and expensive finishing operations, can be produced. Other advantages of my invention are hereinafter set forth- I am well aware that it has been proposed to spray or atomize a mixture of volatile hydrocarbons,as kerosene or gasoline and facing material uponthe surface of a green sand-mold in an efiort to skin dry the surface of the mold so the metal would lie quietly therein and at the same time effect the application of a facing layer on such surface and particularly upon the vertical and uneven surfaces thereof, but such operations were invariably unsatisfactory in certain respects since the facing layer so applied, due

to the entire absence of any organic bond,

or binder, failed to properly adhere to the mold surfaces. Furthermore, other attempts have been made to incorporate an organic bond or binder with the spray material, such as slicking leads of the type heretofore used,

by mixing molasses water therewith, but the presence of clay or soapstone or like waterabsorbing inorganic material therein prevented the steam generated in the castingoperation from escaping through the mold surface and tended consequently to blow the casting, causing blow holes to be formedv therein, which results were far from satisfactpry i Furthermore, the water with which, the slicking leads were incorporated contained such a high percentage of molasses as to seal the surface of the mold to such an extent as Application filed August 13, 1929. Serial No. 385,692.

to cause scabbing of the casting unless the mold was submitted to a drying operation to remove the water prior to the casting of the metal therein.

My invention avoids the objections heretoas fore encountered when employing the prior art products and renders it possible to produce a remarkably effective coating of carbon substantially free from inorganic water absorbents on the surface of a green sandeoo mold, andespecially as above stated, upon the vertical and uneven orirregular surfaces thereof, with the resultant production of perfect castings from which the adhering sand layer is readily peeled without requiring expensive operations to remove the latter.

In carrying out my invention, I preferably proceed as follows:

For the production of the spray material I usually employ 100 parts of gas carbon of 16 about 200 to 300 mesh fineness and having practically none of the particles smaller than 180 mesh, thesame being intimately mixed in a suitable mixing machine or mill with an extremely small quantity of an organic binder, preferably from about by weight to about 5% of gum tragacanth and in no case exceeding 10% by weight of the mixture, preferably also of about 200 to 300 mesh fineness, the same being substantially so free from colloidal inorganic ingredients capa'ble of preventing the apparent dryin of the material to a skin-coat when spray 1 on the surface of green sand molds.

In employing my improved spraying mate- 35 rial for the sprayin of green sand molds, it

is essential that a t ick or viscous aqueous paste be prepared, as distin ished from a thin liquid, and preferably t e paste should be so thick that it requires some 7 to lbs. 90 of air pressure to effect the spraying of the same from the container in 'which the same is placed but in no event should the mass be so thin that less than 35 lbs. of air pressure is required to eifectthe atomization thereof,

- as if so, the excessive amount of water which is contained in the material spra ed on the mold prevents the proper facing t ereof and consequently has a very deleterious upon the castingproduced in a mold so prepared. In

order to obtain such a thick, viscous mixture, I preferably mix between six and seven and one-half lbs. of the dry mixture, prepared as above described, with about 8 lbs. of water, the dry mixture being added directly to the entire volume of water employed, but in no event should the water content of the pasty mass be below 35% nor more than by weight of the pasty mass.

In spraying the foregoing paste as above described, it is preferable to employ an atom izing spray nozzle such as now commonly employed in various spraying operations in foundries and other industries and to apply the same under an air pressure of about lbs. Obviously higher pressures may be utilized, if desired, but on the other hand, the pressure should not be so great as to destroy or deleteriously affect the mold or prevent the material clinging to the mold surface when the same impinges thereon.

Through the employment of the foregoing method of spraying a mold and the mold resulting from such spraying operation, it is possible to produce castings from which the sand can be readily peeled and which castings are extremely faithful reproductions of the patterns from which the molds have been prepared, as in the casting operation in such molds, the sand erosion is eliminated, so that any disintegration of the mold areas, particularly beads, cams and other projections on the mold surfaces, due to the cutting action of the metal is avoided, since the facing material so applied serves to bind together the green sand particles in the mold surface and to formtherewith a compact surface layer over which the metal readily flows without deleterious action. Furthermore, this improved spray product being particularly adapted as above stated .for the spraying of vertical, concave, convex and other odd shaped surfaces, the piece-work production of each molder can be greatly increased as compared with the laborious operations now required to properly face molds of the foregoing character. Likewise the character of my improved facing material is such that, as above stated, a relatively thick skin-coat can be applied thereto with a consequence that thick, heavy castings can be produced inmolds faced with this material in the manner herein described, which castings are of superior quality and can be freed from the adhering sand without resorting to expensive finishing operations, since not only does this improved facing material adhere better to large surfaces, therefore thinner layers of the same will effect equally as good results as compared with other types of facing materials applied,'but also, as above stated, due to the thick, heavy paste which is sprayed upon the mold, a maximum amount of facing is applied with a minimum amount of molsture. Moreover the moisture present 111 the thick, asty mass of my material applied as above escribed, tends to be absorbed or drawn out of the coating, with the consequence that the facing layer on the mold surface has an apparently dry appearance and therefore there is no tendency for the stream generated to blow holes in the casting or to destroy the surface of the mold during the casting operations.

In lieu of gum tragacanth other organic 7 binders such as dextrine, sugar, gum arabic, gum acacia and the like may be employed, but gum tragacanth, although not expensive, is much preferred by me to the other ingredients in view of its peculiar highly satisfactory properties ofthe same which render it particularly adaptable for use in the foregoing composition.

The term non-graphitic as employed in the claims has reference to amorphous, lusterless, non-unctuous products which are diflicultly combustible and quite refractory, but less so than the natural graphites, or their prototype artificial graphite made in an electric furnace. Among these products in addi- 00 tion to those herein specified which are suitable for use as a substitute for the gas carbons above noted is lamp black.

The term gas carbon is used herein in its broadest significance to include carbon obtained from the decomposition of gas, whether carbon black, the product produced by the decomposition of natural gas, to the amorphous, lusterles's form of carbon, known as retort carbon, which is obtained from the 101 retorts used in the manufacture of illuminating gas.

Various other ingredients than those herein specified capable of functioning the same and which are embraced within the scope of 105 the appended claims and various modifications in the method of making the product from that herein described may be employed without departing from the spirit of my invention.

Having thus described my invention, what I claim and desire to obtain by United States Letters Patent is:

1. The method of casting metal in green sand molds which comprises forming a green sand mold conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous mixture containing principally, a substantially nongraphitio, lusterless, artificial carbon and a small percentage, not exceeding 6% by weight of the mixture, of a water-soluble bonding material, closing the mold and then pouring metal into said mold and recovering the resultant casting.

2. The method of casting metal in green sand molds which comprises forming a green sand mold' conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous mixture containing principally a substantially non-graphitic, lusterless, artificial carbon and a small percentage, not exceeding 3% by Weight of the mixture, of a water-soluble bonding material, closing the mold and then pouring metal into said mold and recovering the resultant casting.

3. The method of casting metal in green sand molds which comprises forming a green.

sand mold conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous aqueous mixture containing principally nongraphitic, lusterless, carbonresulting from the decomposition of gaseous hydrocarbons and a small percentage, not exceeding 5% by Weight of the mixture, of a water-soluble gum, closing the mold and then pouring the metal into said mold and recovering the resultant casting.

4. The method of casting metal in green sand molds which comprises forming a green sand mold conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous aqueous mixture containing principally a non-graphitic, amorphous carbon resulting from the decomposition of gaseous hydrocarbons and containing not more than 60% of water, containing a small percentage, not exceeding 5% by weight of the mixture of a water-soluble bonding material, the spraying operation being accomplished by the intimate admixture which such aqueous mixture of air under an initial pressure of not lessthan 40 lbs. per sq. in. and then pouring metal into said mold and recovering the resultant-roasting.

5. A facing material for spraying green sand molds, comprising a diflicultly combustible substantially non-graphitic, amorphous form of carbon resulting from the decomposition of hydrocarbon gases anda small percentage, not exceeding 10%, of a water-soluble binder intimately incorporated with such carbon, said mixture being essentially free from insoluble inorganic colloids and being adapted to form an apparently dry skin-coat on the surfaces of green sand molds to which it is applied, whichcoat is permeable to the steam generated in the casting operation.

6. A facing material for spraying green sand molds, comprising a diflicultly combustible, non-graphitic, amorphous form of carbon resulting from the decomposition ofhydrocarbon gases and a small percentage, not exceeding 5%, of a water-soluble binder intimately incorporated with such carbon, said mixture being essentially free from insoluble inorganic colloids and being adapted to form a skin-coat on the surfaces of green sand molds to which it is applied.

7. A facing material for spraying green 65' sand molds, comprising adifficultly combustible, non-graphitic, amorphous form of carbon resulting from the decomposition of hy-' drocarbon gases and a small percentage, not exceeding 3%, of a water-soluble binder intimately incorporated with such carbon, said mixture being essentially free from insoluble inorganic colloids and being adapted to'form a thick skin-coat on the surfaces'of green sand molds to which it is applied.

8. A facing material for spraying green sand molds, consisting of in excess of 95% of gas carbon and not more than 2% of a watersoluble gum intimately incorporated therewith, said mixture being capable of forming a skin-coat on the surfaces of green sand molds when sprayed thereon in the form of an aqueous pasty mass.

9. A green sand mold for casting metal, having its inner walls covered with a skincoat-of a mixture of a diflicultly combustible, amorphous form of carbon resulting from the decomposition of gaseous hydrocarbons and a very small percentage of an organic binder, such skin-coat containing in excess of 95% of ingredients which exert a peeling action on the resultant casting.

10. A green sand mold for casting metal,

having its inner walls covered with a skincoat of a mixture of a difficultly combustible, amorphous form of carbon resulting from the decomposition of gaseous hydrocarbons and a very small percentage of an organic binder, such skin-coat containing in excess of 90% of ingredients which exert a peeling action on the resulting casting and bein substantially free from colloidal inorganic ingredients capable of preventing the apparent drying ofsuch skin-coat.

11. The method of casting metal in green sand molds which comprises forming a green sand mold conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous mixture containing principally finely divided carbon and a small percentage, not exceeding 6% by weight of the mixture, of a water-soluble bonding material, closing the mold and then pouring metal into said mold and recovering the resultant casting.

12. The method of casting metal in green sand molds which comprises forming a green sand mold conforming to the desired casting and superficially spraying the surfaces of the 0 en mold witha thick, viscous mixture containing principally finely divided carbon and a small percentage, not exceeding 3% by weight of the mixture, of a water-soluble bonding material, closing the mold and then pouring metal into said mold and recovering the resultant casting.

13. The method of casting metal in green sand molds which comprises forming a green sand moldconforming to the desired casting and superficially sprayingthe surfaces of the open mold with a thic viscous aqueous mixture containing principally amorphous carbon and containing not more than 60% of water, and containing a small percentage, not exceeding 5% by weight of the mixture, of a 5 Water-soluble bonding material, the spraying operation being accomplished by the in timate admixture with such aqueous mixture of air under an initial pressure of not less than 40 lbs. per sq. in. and then pouring metal into said mold and recovering the resultant casting.

14. A facing material for spraying green sand molds, comprising a dlflicultly combustible, finely divided carbon and a small percentage,-not exceeding 10%, of a watersolublebinder intimately incorporated with such carbon, said mixture being essentially free from insoluble inorganic colloids and being adapted to form an apparently dry skin-coat on the surfaces of green sand molds to which it is applied, which coat is per meable to the steam generated in the casting operation.

15. The method of casting metal in green sand molds which comprises forming a green sand mold conforming to the desired casting and superficially spraying the surfaces of the open mold with a thick, viscous, aqueous mixture consisting principally of finely divided carbon and containing a small percentage, not exceeding'5%-by weight of the mixture, at a water-soluble bonding material and not more than 60% of water, the amount of bond-= ing material and water being such that the mold surfaces can absorb the water, whereby the blowing of the casting by steam. during the casting operation will be prevented, and such spraying operation being accomplished by the intimate admixture with said 4 aqueous mixture of air at an initial pressure of not less than 40 lbs. per sq. in. and then pouring the metal to be cast into said mold and recovering the resultant casting.

Signed at New York, in the county of New York and State of New York, this 5th day of August, 1929.

- BENJAMIN F.,WALLACE.