US2471049A - Apparatus for coating ingot molds - Google Patents

Description

y 1949. A. w. THORNTON ETAL 2,471,049

APPARATUS FOR COATING INGbT MOLDS Filed Dec, '5, 1945 Y s Sheets-Sheet 1 1720676507 5. 42mm? #4 7/70/6170! lwwz' firflmer and awn 055054 May 24, 1949. A. w. THORNTON ETAL 2,471,049

APPARATUS FOR COATING INGOT HOLDS Filed Dec. 5, 1945 s Sheets-Sheet 2 A. w. THORNTON EI'AL 2,471,049

APPARATUS FOR COATING INGOT MOLDS May 24, 1949.

Filed Dec. 5, 1945 3 Sheets-Sheet 3 mwmam- Patented May 24, 1949 APPARATUS FOR COATING INGOT MOLDS Arthur W. Thornton, Pittsburgh, Lindsey Stewart, McKeesport, and Francis Susa, Pittsburgh, Pa.

I Application December 5, 1945, Serial'No. 632,824

The present invention relates to improvements in ingot, mold coatings and more particularly to an apparatus for applying the same.

It has been proposed in the past, to coat the inner surfaces of ingot molds prior to casting the ingot. Various materials have been employed for the purpose, including slurries of clay,

powdered metals, tar, pitch, various carbohydrates and other organic materials. However, in order to coat satisfactorily the inside of molds with such coatings, it was necessary to dip the whole mold since it has heretofore not been possible to secure a uniform coating of the desired thickness on the inside surfaces by prior art methods. Such dipping procedure is of course wasteful in that the coating material on the outside surfaces is wasted.

- A primary object of the present invention is to provide an apparatus for quickly and uniformly coating the inner surfaces of an ingot mold.

A further object of the invention is to provide an apparatus utilizing a dry, easily liquifiable material. or a mixture thereof with other coating material for uniformly coating the inner surfaces of heated ingot molds.

According to the present invention, it has been found, that thin, uniform coatings can be applied to the inner surfaces of metal molds, utilizing carbonaceous materials, preferably comminuted pitch. The hot molds are immersed in a water bath to remove sand, scale, etc. and to reduce their temperature to within a range wherein the pitch will liquify but not carbonize. The molds are then placed upright on a base having a plurality of openings through which the comminuted pitch can be blown upwardly preferably admixed with a fluid, such as air. The temperature inside the mold or adjacent the mold surfaces should preferably be high enough to at least partially volatilize the finely divided pitch as it rises upwardly therethrough. The so-treated pitch thereby forms a thin, uniform, lustrous film or coating on the inner surfaces of the ingot mold. The film or coating thickness depends on controllable variables such as the time and density of the application of the air-pitch mixture.

In addition to pitch, other known dry, moldcoating materials, such as the various carbohydrates, can be employed. Preferably, such materials should have a relatively low melting temperature and be finely divided. These materials can serve as a binder for and be mixed with other difficultly liquiflable coating materials,

.3 Claims. (Cl. 22-88) 2 more particularly powdered metals, such as aluminum, to provide additional chemical and physical benefits.

The foregoing objects and method can be better understood by reference to the drawings, wherein:

Figure 1 is a plan view;

Figure 2 is an elevation, partly in section;

Figure 3 is an isometric view; and

Figure 4 is an enlarged cross section of a valve member.

Referring more particularly to the drawings, wherein there is shown a preferred form of apparatus for applying powdered pitch to the interior of ingot molds, the numeral 2 designates a hopper for holding powdered pitch. The pitch is placed in the hopper 2 from bags of original shipment. Suction lines 4 having rubber T1058 nozzles 6 dipping into the hopper 2, siphon the powdered pitch from the hopper and the force of compressed air in operating lines 8, passing through the siphons l0, picks up this pitch and carries it through lines l2 and forces it out of nozzles It in base [6 into molds 20 disposed thereon.

The molds 20 are adapted to be simultaneously placed on base it by means of lifting tongs 22 carried by a suitable crane (not shown). Flexlbly mounted in the tongs 22 is a cover plate or baffle '24 which is adapted to rest upon the upper surfaces of the mold, partiall closing the upper end thereof. It is to be noted that the cover 24 does not fit tightly on the molds but suflicient leakage is permitted to obtain good circulation in the molds and thus carry pitch u;1iformly over the entire inner surfaces there- 0 Operating lines 8 are connected to suitable source of air under pressure by line 26 through valves 28 which are normally closed and are adapted to be opened for a predetermined interval by cams 30 on-a rotatable cam shaft 32 connected to a motor 34 through a speed reducer 3B. A limit switch may be included in the motor circuit to stop the motor after the cam shaft 32 has made a complete revolution.

A Water separator or air dryer 38 is placed in the air supply line 26 and the Water extracted from the air line is discharged through outlet 40.

Finely powdered pitch has a tendency to pack tightly in the hopper if not disturbed. To overcome this packing tendency, nozzles 42 are placed in the lower portion of the hopper 2 and are connected to lines 8 through check valves 44. Thus when any of the valves 28 are open, a controlled volume or gust of air passes through nozzles 42. This light blast of air in the hopper lifts the pitch and keeps it in a loose fluffy condition. The nozzles 42 may have a spring-biased cover 46 to keep the pitch from settling therein. The hopper 2 is placed as close to the base l6 as possible to keep the lines l2 from clogging.

In operation, the molds after having a previously cast ingot removed therefrom are immersed in a bath of cooling fluid such as water to lower the temperature to a point within the range of 250 to 650 F. The molds are then deposited on the base i6 so that the nozzles M are centrally located in the bottom openings of the mold. The cover plate 24 rests loosely on the top of the mold to permit some circulation therethrough. The motor 34 is then energized to turn the cam shaft 32 and cams 39 to open the valves 28 for a predetermined time interval. With air pressure of about 40 to 95 pounds per square inch and with pitch comminuted to pass a 100 mesh screen, a five-second application on a five-ton ingot mold will give a coating of the desired thickness. The above temperature is such that when powdered pitch is injected into the interior of the mold and comes in contact with the heated walls, it is deposited as a thin lustrous coating or film thereon. The film thus formed and de- I molds and the like comprising in combination a posited is firmly adherent, not fiowable and is quite uniform from the top to the bottom of the mold.

A coating so obtained will repel splashes during teeming and will agitate the rising surface of the steel adjacent the mold walls just sufflciently to prevent non-metallic scum from be- .claims.

We claim:

1. Apparatus for coating the interior of ingot molds and the like comprising in combination a base for holding a mold, an upwardly directed nozzle in said base, a loosely fitting cover for the top of said mold, and means for conducting a mixture of air and comminuted coating material under pressure to said nozzle.

2. Apparatus for coating the interior of ingot base for holding a mold, an upwardly directed nozzle in said base, means for lifting said mold, a cover member carried by and movable relative to said lifting means for loosely covering the top of said mold and means for conducting a mixture of air and comminuted coating material under pressure to said nozzle.

3. Apparatus for coating the interior of ingot molds and the like comprising in combination a base for receiving and holding a mold in upright position, an upwardly directed nozzle in said base, a loosely fitting cover for the top of the mold, means for mixing air and comminuted coating material, means for conducting said mixture under pressure to said nozzle for a predetermined time interval, said mixing and directing means comprising a hopper having comminuted coatin material therein, a line connecting a source of air under pressure to said nozzle, a suction member in said line connected to said hopper whereby comminuted coating material will be withdrawn from and mixed with said air under pressure in said line, a valve in said line, cam means for opening said valve, a motor for operating said cam, and a bleeder line connected to said valve controlled line between said valve and said nozzle and opening into the bottom portion of said hopper whereby air under pressure will be admitted to said hopper to aerate said pitch while pitch is being withdrawn therefrom by said suction member.

ARTHUR W. THORNTON. LINDSEY STEWART. FRANCIS SUSA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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