US2007343A - Facing material - Google Patents

Description

Patented July 9, 1935 PATENT oF-FieE 2,007,343 I FACING MATERIAL William J. Rees, Toledo, Ohio No Drawing. Application Dec Serial No. 701,536

ember s, 1932,

, Claims. (01. 22-189) My invention relates to an improved material for facing surfaces of bodies that are brought into contact with molten materials, such as molten metals, and particularly in bodies, such as molds, where the molten metal is maintained in contactual relation with the body during the chilling of the metal.

My invention hasfor an object to provide a facing material resistant to the conductance of heat so that, when the facing material is applied to a mold surface and a molten charge placed contiguous thereto, the facing material will provide a protecting veneer of high heat insulation and refractoriness as will substantially prevent crack ing, scoring, or pitting of the mold surface, or burning of the elements which make up the mold surface.

Another object of my invention is to provide a facing material having physical characteristics conducive to easy application of the facing material to the mold surface, as, for example, by painting, spraying, or dusting, but which, at the same time, by reason of the said physical characteristics, tends to spread evenly and smoothly over the mold surface, presenting a charge approximating surface of fine and even texture.

. The physical characteristics of the facing material of my invention permit it to be applied as a comparatively thin coat to the mold surface resulting first, in the use of a lesser quantity of facing material; second, in obtaining a relatively absolute definition of contour as between a charge of molten metal and the mold surface; and third, in facilitating the driving off of moisture present in the moldor in the material by the mold heat,"w-hich moisture often generates vapor, on charging, resulting in bubbles and 'disfigurations of the cast.

Another object of the invention is to provide a material, the ingredients of which are bonded" together and are resistant to separation or cracking after application thereof to the surface to be protected, thereby preventing subsequent contact -of: the molten charge with the mold surface and resultant cohesion" therewith. My invention, therefore, provides a mold facingmaterial which willpermit easy delivery of a cast from themold after the chargehas become chilled sufliciently to maintain itself in a substantially solidifiedform.

My invention has for a particular object to provide a mold facing material having an ingredient therein tending, on contact with a molten charge, to enter a semi-liquid state in which condition the ingredient facilitates the passage and entry of the fluid molten charge into the mold, thereby substantally preventing the disruption of the surface tension of the molten charge throughout the pouring and cooling thereof, and resulting, of a relatively smooth and close-grainedsurface on the cast.

My invention has for a further particular object to provide a mold facing material having an ingredient therein tending, on contact with the molten charge, to enter a semi-liquid state and effect, together with the other ingredients, the formation of a skin resistant to heat trans mission therethrough, and on cooling of the charge,'tending to craze, thereby physically disturbing the relation of the cooled cast to the mold walls and operating to forces as are normally and the cast, enabling cast from the mold.

The invention consists in other features and advantages which will appear from the following description. Compositions containing the invention may partake of different forms and still embody the invention. To illustrate a practical application of the invention, I have selected a preferred composition of facing material used in conjunction with surfacing a permanent mold as an example of the various compositions and details thereof that contain the invention and shall describe the/selected facing material composition, hereinafter, it being understood that variations may be made without departing from the spirit of the invention.

My invention is embodied in a composition containing, among other things, a quantity of ground glass particles. Preferably, the glass is ground to a highly pulverulent dust form so as to permit easy spreading or application thereof to the mold surface preliminary to charging thereof, and to effect even distribution of the material over the mold surface. The facing material com position also preferably contains a quantity of preferably highly pulverulent sand, and a small quantity. of a binder, such as plaster, or fireclay. The sand in bond comprises the major portion of the holding body for the glass.

The sand and glass, in an intimate association of the pulverulent body, does, by its very physical minuteness, tend to resist the transition of heat. Each particle of the ingredients of the material being a heat absorbing body, there will be presented, in' a given area over a tected, a large number of heat absorbing units, each of which absorbs heat from the molten charge and prevents the full and destructive overcome such adhesional exerted between the mold freedelivery of the cooled surface to be prov on cooling, in the production transmission of heat to the protected container surfaces.

The particles of glass approach a state of fusion upon contact of the molten charge andspread in a somewhat plastic state over the surface of the mold, forming with the said particles 9. yieldable skin resistant to heat transmission in a degree sufficient to protect the mold surface. Upon cooling, the charge and the mold experiences contraction to a degree materially different than that experienced by the skin and by reason of said differential of thermal contraction, and also by reason of thermal activity within the ingredients of the skin a separation and shattering. of the skin is effected thereby freeing the cooled charge and permitting easy delivery thereof from the mold.

The material of my invention may be applied by dusting, or by painting or spraying, in the latter cases the material is mixed with a liquid, such as water or oil, and will maintain itself in suspension with little or no agitation over relatively long periods of time. The material may, however, be mixed with other substances, such as suitable binders or retainers. Further, the material may be mixed with other well known founding materials, such as graphite, ground carbons and cakes, steatite, cement or carbide of silicon in varying proportions, as determinable by the specific need and conditions of use. By so combining the material of my invention with other materials, various immediate and resultant effects may be obtained on the molten charge.

In the particular facing material selected to illustrate an embodiment of my invention, with particular adaptation thereof to a permanent mold, as, for example, of the type common to pig casting machines,'I prefer a material having approximately seventy-five per cent or three parts ground sand, and approximately twenty-five per cent or one part ground glass. The sand and glass may be ground to a highly pulverulent dust state in a suitable grinder. Preferably, the grinding of both materials is effected at the same time, and in the same grinders which serve, therefore, not only to grind the ingredients, but also to intimately mix the same. As illustrative of the pulverulency found to be desirable, of a given quantity, practically all will pass through a U. S. standard No. 325 mesh sieve, and only approximately thirty-five per cent will be retained on the equivalent of a U. S. standard No. 700 mesh sieve.

During the grinding of said sand and glass and intimate mixing thereof, it is desirable to add a dry bonding ingredient, such as plaster or fire clay. The amount may be varied according to the strength of bond desi ed, but for general purposes, I find one-tenth of one per cent (0.1%) by weight suitable. If, after .the material has been removed from the grinding process,- it is found a greater bond is required, the same may be obtained by mixing the material intimately with a commercial fire clay or further amounts of plaster, or materials of like character.

A variety of close-grain effects on the chilled cast are obtainable by variation of the quantity of ground glass specified above, the chilled cast having a surface of increased gloss with addition of further ground glass. These modifications are appreciated and comprehended in my invention.

In using the facing material of my invention, as particularly relates to molds of pig casting machines, I prefer to mix the material with water so as to completely saturate the water with the material, which, by reason of its insolubility and pulverulency, will be readily maintained in suspension over a comparatively long period of time. The water combination of the material may then be painted, as by a swab or brush, on the walls of the mold, or may be placed in a spraying apparatus and atomized for spraying on the walls of the mold. Ihe material will spread itself uniformly and intimately over the surface of the mold and will cling thereto, even though later dried by the heat of the mold, by reason of the bonding ingredient and minuteness of the other ingredient particles. Other liquids may be used to form a solution if desired. For example, oil may be mixed with the material, and such combination painted on the mold surface.

The molds of pig casting machines are usually carried on a suitable linked conveyor which carries the mold from a point of charge to a point of delivery of the cast and returning to the charging point. In the course of travel from the delivery point to the charging point, the charge receiving surfaces of the mold are subjected, as by spraying, to a surface treatment of facing material, such as the material of my invention.

I claim:

1. In a facing material for surfaces exposable to molten metals comprising a mixture of a quantity of pulverulent silica, a quantity of pulverulent glass, and a quantity of a bonding ingredient.

2. In a facing material for surfaces exposable to molten metals comprising a quantity of pulverulent glass and a carrying body for said pulverulent glass.

3. In a facing material for mold surfaces comprising the mixture of three parts pulverulent sand and one part pulverulent glass.

4. In a facing material for mold surfaces comprising the mixture of pulverulent sand and pulverulent glass in water suspension.

5. In a facing material for mold surfaces comprising the mixture of sand and glass ground to such a pulverulency that in excess of fifty percent of the mixture will pass through a 700 mesh sieve.

6. In a facing material for mold surfaces comprising the mixture of three parts pulverulent sand, one part pulverulent glass, and a physical bonding ingredient.

7. In a facing material for surfaces exposable to molten metals comprising a mixture of pulverulent glass and a pulverulent'refractory ingredient.

8. In a facing material for surfaces exposable to molten metals comprising a mixture of pulverulent glass and pulverulent silica.

9. In a facing materal for surfaces exposable to molten metals comprising a mixture of pulverulent glass and a pulverulent refractory ingredient in liquid suspension.

10. In a facing material for surfaces exposable to molten metals comprising a mixture of pulverulent glass and pulverulent silica/in liquid suspension.

WILLIAM J. REES.