US1920244A - Method of making cast products - Google Patents

Description

Aw@ L 3933.1 D. s. CONNELLY ET m.

METHOD OF MAKING CAST PRODUCTS Filed June 3, 1952 gwuefnfiow Patented Aug. 1, 1933 UNITED STATES PATENT OFFICE Hahn, Canton, Ohio,

assignors to Wooster Products Inc., Wooster, Ohio, a Corporation of Ohio Application June 3, 1932. Serial No. 615,172

9 Claims. (Cl. 22-202.)

Our invention relates to a method of casting products having an abrasive surface, and more particularly to a method of casting metal stair treads and the like, the wearing portion of which is impregnated with granular abrasive material.

The common method of providing cast stair treads with an abrasive Wearing surface, is to sprinkle a layer of the granular abrasive on a mold surface, and then spray the layer of abrasive with a suitable binder, such as asphaltum. When the molten metal is poured into the mold, the binder functions to mechanically hold the particles of abrasive to the mold surface until the binder becomes gasied, at which time the molten metal has become sufficiently quiescent to restrict the tendency of the particles of abrasive to rise because of their relatively low specific gravity.

It has been found that this method provides only a relatively thin layer of abrasive upon the outer wearing surface of the tread, for the reason that no substantial penetration of the particles of abrasive into the iron is obtained, with the result that the particles of abrasive are easily dislodged and soon worn off.

Other prior methods, of which we are aware, all provide for mechanically holding the particles of abrasive to the mold surface until the bolten metal becomes quiescent; and these methods do not produce a coating of abrasive which is impregnated into the cast metal to a depth sufficient for producing long wear. It is therefore an object of the present invention to provide a method of producing a casting having a wearing portion impregnated to a substantial depth with granular abrasive material.

Another object is to provide for chemically holding the particles of abrasive from rising in the molten metal when the same is introduced into the mold.

A further object is to provide for substantially surrounding the particles of abrasive with a slag or ux during the casting, which slag or ux intermingles to some extent with the molten metal.

These and other objects are attained by the improvements comprising the present invention, which will be hereinafter pointed out in detail.

The improved method may be stated in general terms as including, sprinkling the drag surface of a mold with a layer of pulverulent inorganic compound having a `relatively low melting point as compared with the molten metal to be cast, spreading a layer of granular abrasive over the layer of inorganic compound, springling another layer of the pulverulent inorganic compound over the abrasive, and then slowly introducing molten metal into the mold.

In the accompanying drawing Figure 1 is a fragmentary sectional view of a mold at the beginning of the introduction ofl 30 molten metal thereinto, showing the composite layer of granular abrlsive and pulverulent inorganic compound on the dragsurface of the mold;

Fig. 2 is an enlarged sectional view similar 65 to Fig. 1, showing the composite layer of pulverulent inorganic compound and granular abrasive prior to the introduction of molten metal into the mold; and

Fig. 3 is a greatly enlarged fragmentary sec- 7o tional view of the finished product, conventionally illustrating the character of the wearing portion.

Similar numerals refer throughout the several views.

The invention may be carried out in an ordinary mold as shown in Fig. 1, having the cope 10 and the drag 11. The mold cavity 12 is located in the drag, and has the inlet gate 13 communicating with the cavity l2, and the pouring sprue 14 communicating with gate 13.

A well 15 is preferably provided at the bottom of the pouring sprue, so that the molten metal 16 `will flow slowly laterally over the bottom of the mold cavity.

In carrying out the invention, a layer of pulverulent inorganic compound indicated at 17 in Fig. 2 may be sprinkled over the drag surface 18 of the mold cavity 12. Next a layer of granular abrasive indicated at 19 in Fig. 2 may be spread over the layer of pulverulent inorganic compound. Then another layer of the pulverulent inorganic compound, as shown at 20 may be sprinkled over the granular abrasive 19. The pulverulent condition of the inorganic compound causes some of the particles of the layer 20 to lill in the interstices between or intermingle with particles of abrasive and form a composite layer of inorganic compound and abrasive as indicated generally at 21 in Figs. 1 and 2.

The granular abrasive used is preferably of relatively low specic gravity and may be corundum or carborundum. The requisite characteristics of the pulverulent inorganic compound include a relatively low melting point as compared with 105 the molten metal from which the stair tread is to be cast, and the ability to form at low temperatures a sticky mass which immediately forms a slag or flux around the particles of abrasive to hold them from rising in the molten metal, which 110 to similar parts present improved method, since the melting point of each of these compounds is below 800 centigrade, or considerably less than the melting point of iron, and each of these compounds forms a sticky, slaggy mass at low temperatures.

In carrying out the improved method, satisfactory results have been obtained by pouring the molten metal after the layer of abrasive material has been added Without sprinkling any of the pulverulent inorganic material over the abrasive; or by iirst spreading the layer of granular abrasive upon the mold surface and then sprinkling pulverulent inorganic material thereover; but we prefer to form the composite layer as previously described.

After the composite layer 21 has been formed upon the mold surface 18, the molten iron 16 is poured through the pouring sprue 14. By providing the Well 15, the metal may be made toiiow laterally over the composite layer 21, as shown at 22, at a slow rate. Due to the relatively low melting point of the molten metal, the inorganic material in the immediate region of the advancing molten metal immediately forms a sticky mass, which may be a slag or ux, around the particles of abrasive.

As the molten metal advances slowly, the pulverulent inorganic material will form a slag or flux, adhering to the mold surface and around the particles of abrasive, rapidly enough to provide against any material erosion or washing of the composite layer 2l due to the advance thereover of the molten metal.

The formation of the sticky mass or slag around the particles of abrasive prevents them from rising in the molten metal due to their relatively low specific gravity. At the same time, the molten slag or ux and the molten iron intermingle to a considerable extent before the mass becomes chilled, with the result that, in the iinished article a relatively great depth of penetration of the granular abrasive into the molten cast metal is obtained.

In the present method, instead of mechanically holding the particles of abrasive to the molten surface before the molten metal is introduced, the particles are held by chemical action, because the heat of the molten metal transforms the pulverulent inorganic material intoa sticky, slaggy mass which surrounds and restricts the movement of the granular abrasive particles during the casting operation.

The slag or flux thus formed intermingles sufciently with the molten metal to result in the formation of a heterogenous wearing portion in the finished product, as indicated at 23 in Fig. 3, possessing substantial depth and composed of granular abrasive 19 and a slag or flux indicated by the dash line cross-hatching, which is intermingled With the cast metal 24, as conventionally illustrated in Fig. 3.

We claimz- 1. The method of casting metal products embodying an outer abrasive wearing portion, which includes sprinkling a mold surface with pulverulent inorganic material having a relatively low melting point, spreading a layer of granular abrasive material over the pulverulent inorganic ma terial, and slowly introducing molten metal into the mold.

2. The method of casting metal products embodying an outer abrasive wearing portion, which includes spreading a layer of granular abrasive material on a mold surface, sprinkling a layer of pulverulent inorganic material having a relatively low melting point over the granular abrasive material, and slowly introducing molten metal into the mold.

3. The method of casting metal products embodying an outer abrasive wearing portion, which includes sprinkling a mold surface with pulverulent inorganic material having a relatively low melting point, spreading a layer of granular abrasive material over the pulverulent inorganic material, sprinkling another layer of the pulverulent inorganic material over the granular abrasive material, and slowly introducing molten metal into the mold.

4. The method of casting metal products embodying an outer abrasive wearing portion, which includes sprinkling a mold surface with pulverulent inorganic material which forms a sticky mass at a relatively low temperature, spreading a layer of granular abrasive material over the inorganic material, and introducing molten metal into the mold.

5. The method of casting metal products embodying an outer abrasive wearing portion, which includes spreading a layer of granular abrasive material, on a mold surface, sprinkling a layer of pulverulent inorganic material which forms a slag at a relatively low temperature over the granular abrasive material, and introducing molten metal into the mold.

6. The method of casting metal products embodying an outer abrasive Wearing portion, which includes sprinkling a mold surface with pulverulent inorganic material which forms a flux at a relatively low temperature, spreading a layer of granular abrasive material over the inorganic material, sprinkling another layer of the pulverulent inorganic material over the granular abrasive material, and slowly introducing molten metal into the mold.

7. The method of casting iron products embodying an outer abrasive wearing portion, which includes sprinkling a mold surface with pulverulent inorganic material having a melting point below 800 centigrade, spreading a layer of granular abrasive material over the inorganic material, and introducing molten iron into the mold.

8. The method of casting metal products embodying an outer abrasive Wearing portion, which includes spreading layers of granular abrasive material and pulverulent inorganic material having a relatively low melting point one upon the other upon a mold surface, and slowly introducing molten metal into the mold.

9. The method of casting metal products embodying an outer abrasive wearing portion, which includes covering a mold surface with a composite layer of pulverulent inorganic material having a relatively low melting point intermingled with granular abrasive material, and slowly introducing molten metal into the mold.

DONALD S. CONNELLY. THEODORE J. HAHN.

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