US2397789A

US2397789A - Method and apparatus for casting metal

Info

Publication number: US2397789A
Application number: US534829A
Authority: US
Inventors: Robert K Hopkins
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1944-05-09
Filing date: 1944-05-09
Publication date: 1946-04-02
Anticipated expiration: 1963-04-02

Description

April 2, 1946. R. K. HOPKINS METHOD AND APPARATUS FOR CASTING METAL Filed May 9, 1944 ATTORNEY Patented Apr. 2, 1946 UNITED STATES METHOD AND APPARATUS FOR CASTING METAL Robert K. Hopkins, New York, N. Y., asslgnor to The M. W. Kellogg Company, New York, N. Y.. a corporation of Delaware.

Application May 9, 1944, Serial No. 534.829

2 Claims.

The present invention relates to a method and apparatus for casting metals.

In teeming metal from a furnace or other metallurgical vessel into a mold such as an ingot mold, the molten discharge stream i exposed to the atmosphere before being deposited in the mold. If the metal is discharged from the vessel through an extended spout or conduit reaching into the mold close to or below the surface of the fluid therein, atmospheric contamination of the metal being'poured is avoided. The highly heated mold without exposing the molten stream to atmospheric contamination.

In carrying out certain features of the present invention, the metal is streamed into the mold under a layer of flux or slag. The molten stream is conducted through a spout or conduit into the mold. A protective sleeve embraces this conduit and extends to the slag layer in the mold, so that the molten stream is hermetically sealed while being transferred to said mold. Any erosion or disintegration of the lower end of the stream conduit will not break the seal maintained by the protective sleeve. t

Various other obiects, features and advantages of th invention will be apparent from, the following 'particular description. and from an inspection of the accompanying drawing showing somewhat diagrammatically in vertical section.

and apparatus which may be employed to. carry out the process features, of the present invention, and which embodies the structural features of the invention.

Referring to the drawing. there is shown a mold III which may constitute the usual ingot mold made of suitable material, and which may be conventionally shaped and designed. In the specific form shown, this ingot mold i is cylindrical in shape and is made of cast iron or copper.

The mold ill contains a layer of flux ll serving to remove and float out impurities from said metal deposited in the mold. Flux 'II also serves as a blanket to protect the deposited metal I! from atmospheric contamination, and as an insulator to conserve the heat of said metal at the top. The flux l i may be of any composition suitable to perform its desired functions. For example. it may comprise silicates or components of silicates, such as manganese silicate, calcium silicate, aluminum silicate, glass and the like.

The molten metal is poured into the mold Ill from a vessel or reservoir II, which may be of any suitable size. shape or design, but which is specifically shown as a furnace having an over- (Cl. 2H1) flow discharge conduit or spout ll on one side extending to the mold ID. This furnace I3 is shown having a metal shell II with an inner refractory lining l6.

5 As far as certain aspects of the invention are concerned. ferrous metal, or any other type of metal, may be produced in the furnace il in any suitable manner. Specifically, the metal is shown produced in this furnace II by a series of consumable electrodes ll (only one being indicated) submerged at their lower ends in a floating flux or slag layer it. and containing at least some of the ingredients of the metal to be produced.

These electrodes II are spaced by respective flux submerged gaps from the bath I! of metal produced and deposited, and are connected in the circuit of said metal. so that current of sufficient intensity is discharged across said gaps to create metal fusing zones in and around said gaps. The electrode metal and other additional metal ingredients in granular, pellet 0r pulverulent form. fed insaid zones are fused and deposited in the furnace l8. As the metal is produced in the furnace it, it is refined by the flux II. For that purpose. the flux It may be similar in composition to the mold flux I l.

A suitable skimming baille 20 may be provided for drawing back the slag layer It as the furnace metal I! flows towards the spout I.

The spout I4 is desirably cylindrical in shape at its lower discharge end, and may be of any suitable heat-resistant material. In the specific form shown, this spout H has the metal shell I! with its inner refractory lining l6 forming a continuation of the furnace wall structure. Even though the lower end of the spout i4 may be made to extend initially to or below the surface of the slag i i. this lower spout end will eventually be consumed as shown. due to the erosive or corrosive action of the high temperature molten stream 2i or of the slag ii. so that said stream will be exposed to the atmosphere before being discharged into said slag.

To hermetically seal the stream 2| against 45 atmospheric contamination as it is deposited in the mold Ill, irrespective of the condition of the lower end of the spout ll. there is provided a protective sleeve 24 embracing the lower end of the spout ll with a snug tight hi: and extend- 50 ing to or slightly below the surface of the slag II. This sleeve 14 may be made to embrace the spout ll with the metal shell I! thereon, but it is desirable to remove the lower section of said shell and have said sleeve snugly embrace the 55 refractory section of the spout as shown.

The sleeve 24 is desirably of a metal having high heat conductivity such as copper, and its cylindrical wall 25 is advantageously hollowed to permit continuous circulation of a cooling liquid 0 such as water therethrough during the mold pouring operation. The lower section of the sleeve wall 25 is desirably bevelled so as to provide a comparatively narrow edge 28. This. V-shaped edge construction facilitates entry of the lower end of the sleeve 24 into the mold slag II in case it is desired to extend this sleeve end below the surface of said slag in sealing position. In actual operation, it is desirable to have the V- shaped edge of the sleeve 24 Just reach the surface of the mold slag ii as shown. Due to surface tension and capillary action, this slag It will be attracted to and elevated along the bevelled sides of the lower sleeve edge as shown, and will solidify in this position, so that a solid slag seal 21 will be formed between said sleeve edge and the slag layer during mold pouring operations. Even though this slag seal 21 should break during mold pouring operations, it will be immediately reformed as a resultof the cooling action of the liquid circulated through the hollow sleeve wall 25, so that this seal will be continuously and effectively maintained during the entire mold pouring period. with this arrangement,

even though the lower end of thespout i4 is consumed as shown, the molten stream-Ii will still be hermetically sealed by the non-consumable protective sleeve 24.

As the level of the deposited metal I! in the mold Iii rises, the level offtheslag ll in said mold also rises, so that during mold filling operations, ,the mold and the sleeve 24 must be'airially moved relatively to maintain a constant sealins position between said sleeve and the surface of said slag. This may be accomplished bymaintainlng the mold l0 stationary while the spout 5 i4 and its protective sleeve 24 are raised with the rising slag level, or by keeping'the spout and the sleeve stationary while the mold i0 is moved downwardly at a rate corresponding to the rate of deposition of the metal therein. The latter expedient shown in the drawing may be the simpler, more practicable one, especially in cases where the spout I4 is rigid with the furnace.

The mold Iii may be moved downwardly durin 4 the pouring action in any suitable manner. In the specific form shown, the mold ill with its conventional stool Ii is supported on a platform 32 fixed to-'a vertical shaft II. A worm wheel 84 threaded on this shaft 33 and supported against vertical movement is rotated by a worm I! driven from an electric motor 88.

The downward movement of the mold III is desirably automatically controlled to maintain the position of the sleeve 24 substantially constant with respect to the slag II. In the specific form shown, a pilot electrode 38 extends into the mold ill with its lower end submerged in the shaft ii and spaced by a current discharge gap 40 from the metal I! deposited in said mold. This electrode 38, which is of non-consumable construction and which is axially fixed with respect to the sleeve 24, is connected in the circuit of the deposited mold metal II, as for example, through leads 4! and 42 connected to a control unit 44 energized from a source 45 of electric current.

ass-rhea sealing relationship with respect to the surface of the slag ll, so that the molten stream 21 will be maintained free from atmospheric contamination from the time it is produced in the furnace it to the time it solidifies in the mold Ill.

The details of the pilot electrode 38, and the control unit 44, and the manner in which these regulate the operation of the motor 36 have not been set forth with any great particularity, since the invention 'does not lie in these structures per se, and since these are well-known in the art.

As far as certain aspects of the invention are concerned, instead of employing a, separate electrode 38 to control the position of the sleeve 24 with respect to the surface of the slag H as described, the sleeve 24 itself may be employed as a pilot electrode for that purpose.

In the operation of the apparatus, it is desirable to discharge the metal from the furnace II at a rate which is substantially equal to the rate at which the metal is produced in said furnace. and this rate is desirably substantially the same asthe rate of solidification of the metal in the mold it.

As many changes can be made in the above method and apparatus, and many apparently widely different embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Whatis claimed is:

1. A method of casting, which comprises pouring molten metal into a mold having a body of molten flux therein through a ceramic conduit terminating above the level of the -molten flux, surrounding the molten metal stream as it leaves the ceramic conduit by a metallic sleeve which extends from the end of the ceramic conduit to the surface of the molten flux, and cooling the metallic sleeve to freeze the flux in contact therewith to provide a hermetic seal and thereby protect the molten stream from atmospheric contaminatlon.

2. A casting apparatus comprising a vessel adapted to contain molten metal, a mold adapted to contain a layer of molten flux, and means for transferring the molten metal from the vessel to the mold in the form of a stream while maintaining said stream free from atmospheric contamination, and comprising a discharge spout The pilot electrode 38 may be made of copper, 1

having a ceramic conduit extending into the mold and terminating above the surface of the molten flux, a hollow metal sleeve having its lower edge bevelled embracing the lower end of said conduit and extending to the molten flux with said bevelled edge in contact with said flux, and means for circulating a cooling medium through said hollow sleeve to freeze flux in contact therewith to provide a hermetic seal.

ROBERT K. HOPKINS.