US3628706A

US3628706A - Long life spout

Info

Publication number: US3628706A
Application number: US767729A
Authority: US
Inventors: Chester F Todd
Original assignee: Southwire Co LLC
Current assignee: Southwire Co LLC
Priority date: 1968-10-15
Filing date: 1968-10-15
Publication date: 1971-12-21
Anticipated expiration: 1988-12-21
Also published as: BE740228A; DE1951349A1; ES372535A1; JPS5018861B1; FR2020764B1; GB1283242A; FR2020764A1

Abstract

A long life pouring spout for pouring molten metal in a continuous casting system, wherein the body of the spout is fabricated of graphite and an insulating shield surrounds the pouring spout and prevents air from contacting the outside surface of the pouring spout.

Description

United States Patent Gardner Breymeier Yates Tisdale et al.... Tinnes FOREIGN PATENTS 3/1945 France 12/1961 Pakistan Primary Examiner-Harvey C. Hornsby Assistant Examiner-1'1. S. Lane Attorney-Jones & Thomas Charman et a1.

222/566 266/38 222/566 X 222/566 X 222/566 164/281 X ABSTRACT: A long life pouring spout for pouring molten metal in a continuous casting system, wherein the body of the spout is fabricated of graphite and an insulating shield surrounds the pouring spout and prevents air from contacting the outside surface of the pouring spout.

PATENTED DECZI m1 IINVENTOR. @hww q'odd LONG LIFE srour BACKGROUND OF THE INVENTION In a continuous casting system for casting metal, molten metal is poured from a pouring pot into a channel formed by the groove in the periphery of a rotating casting wheel and an endless metal band surrounding a portion of the periphery of and moving with the casting wheel. A pouring spout delivers the molten metal from the pouring pot which is spaced away from the casting wheel to an area immediately adjacent the intersection of the casting wheel and the endless band. In the past, pouring spouts have been fabricated of various materials, including graphite and silicon carbide which can withstand the elevated heat required in a moltemmetal system and can also be formed with substantially thin wall construction, which is necessary to guide the molten metal to the intersection of the casting wheel and endless band.

While pouring spouts of this construction have been utilized for a number of years, the life of a typical pouring spout is short, usually between 2 and 4 hours of pouring time. The pouring spout must be preheated to a temperature level approximately equal to the temperature of the molten metal before the casting operation starts, and the molten metal flowing through the pouring spout maintains the temperature of the pouring spout at this high level. The elevated temperatures of the pouring spout cause the graphite material of the pouring spout to oxidize and generally deteriorate. Since the molten metal generally fills the inside opening of the pouring spout, the major portion of the deterioration of the pouring spout occurs from its outside surface, due primarily to oxidation of the graphite.

While some attempts have been made to change the composition of the pouring spout to other materials to increase its pouring life, no satisfactory remedy for the short life span of a pouring spout has been developed.

SUMMARY OF THE INVENTION Briefly described, the present invention comprises a pouring spout for pouring molten metal from a pouring pot into the groove of a casting wheel, wherein the pouring spout is protected about its outside or exposed surface from oxidation and the resulting deterioration. The outside surface of the pouring spout is covered with mortar, or a tubular shield fabricated of stainless steel or a similar material, to prevent the air from directly contacting the outside surface of the pouring spout. Also, an inert gas can be applied to the pouring spout, between the pouring spout and its shield, to surround the pouring spout with the inert gas.

Thus, it is an object of this invention to provide a pouring spout in a molten-metalcasting' process which is durable and long lasting.

Another object of this invention is to provide a pouring spout which is protected from oxidation.

Another object of this invention is to provide a pouring spout which is inexpensive to construct, easy to connect to the pouring pot of a metal-casting machine, and which lasts for an extended period of time during the pouring process.

Other objects, features and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a pouring spout as it extends from a pouring pot of a casting system, with a layer of mortar applied to the surface of the pouring spout.

FIG. 2 is a crosssectional view, similar to FIG. 1, but showing the pouring spout having its external surface substantially covered by a metallic shield.

FIG. 3 is a cross-sectional view of a pouring spout, similar to FIGS. 1 and 2, showing a metallic sleeve surrounding the external surface of the pouring spout, and a gas supply conduit communicating with the area defined between the outside surface of the pouring spout and the inside surface of the metal sleeve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIG. 1 shows pouring spout assembly 10 which is connected at its upper end to pouring pot 11. Pouring spout assembly 10 includes graphite spout 12 and mortar covering 13. Graphite spout 12 is generally tubular in configuration and includes inner conduit 14 which extends from end to end, and upper support shank 15 which extends into pouring pot l1.

Pouring pot 11 defines an opening 16 in its bottom surface, which is inwardly tapered throughout at least a portion of its length. Support shank 15 is shaped in a similar manner in that it is larger at its upper end and inwardly tapered downwardly along its length. Mortar I3 is applied to the outside surface of pouring spout 12, substantially over its entire outside or exposed surface. Mortar 13 is applied generally in a uniform surface about spout 12, with possibly a smaller thickness about the lower opening 18 of spout 12. Mortar 13 is of a class that includes a large percent of silicon dioxide, smaller percents of aluminum trioxide, lithium oxide and alkaline earth, with additives including ferrous oxide, copper oxide, magnesium oxide and titanium oxide. One specific mortar which has been found suitable is Adamant firebrick cement, produced by Resco Products, Inc., and comprises: 84.4 percent silicon dioxide, 6.5 percent lithium oxide, 5.25 percent aluminum oxide, 2.6 percent alkaline earth, 0.08 percent magnesium oxide, and 0.07 percent copper oxide. This particular mortar is able to withstand temperatures up to 3,000 F., which is much higher than the temperatures of molten copper or molten aluminum.

Mortar 13 is applied to upper support shank 15 of pouring spout 12 by hand, and when the mortar is at a suitable viscosity, pouring spout 12 is inserted into opening 16 of pouring pot 1 1, from inside pot 11, by wedging pouring spout assembly 10 down through tapered opening 16. The taper of the upper portion of support shank 15 of pouring spout l2 and of opening 16 of pouring pot 11 is such that the downward movement of the pouring spout is limited, and the upper surface 19 about the upper opening 20 of inner conduit 14 is seated at a level where its is substantially coincident to the plane of the inner surface 21 of pouring pot 11. The portion of mortar l3 surrounding support shank 15 functions to seal and bond support shank 15 to the opening 16 of pouring pot 11. Mortar 13 is then applied to the portion of the pouring spout which protrudes from the pouring pot so that the remaining portion of the external surface of pouring spout 12 is sealed from the atmosphere.

After pouring spout assembly 10 has been inserted through the opening of the pouring pot, it should be allowed to dry from 2 to 4 hours, if time permits. If enough time is not available for properly drying the mortar, the heat from the pouring pct 11 will suffice for the purpose of drying the mortar.

Under some conditions it may be desirable to apply fire clay to support shank 15 of pouring spout 12, and mortar to the protruding portion of the spout. Furthermore, it may be desirable to apply the mortar to the protruding portion of the pouring spout before it has been inserted into pouring pot 11. In either case, mortar 13 can be applied by hand without significant difficulty.

Before molten metal is allowed to flow through pouring spout assembly 10, the pouring spout should be preheated to a temperature approximately equal to the temperature of the molten metal to prevent the initial metal flow through the pouring spout from solidifying before it reaches the casting wheel. After the molten metal is allowed to flow through pouring spout assembly 10 the preheating function can be terminated since the molten metal will maintain the temperature of the pouring spout. After the pouring of molten metal begins, the mortar, surrounding the pouring spout insulates the pouring spout from the atmosphere and functions to reduce heat loss from the pouring spout, and the hazard of the molten metal freezing in the pouring spout.

If the mortar 13 surrounding pouring spout 12 should become cracked or otherwise chipped or damaged during or before the pouring operation, mortar 13 can be repaired without terminating the pouring operation by merely applying an additional mortar to the cracked or damaged portion of the assembly. In this manner, the pouring spout does not have to be removed from the casting machine and the casting operation does not have to be terminated to maintain the pouring spout in an oxygen-free environment.-

FIG. 2 shows a pouring spout assembly 25 which includes a pouring spout 26 which is generally similar in configuration to pouring spout 12 of FIG. 1, and a stainless steel shield 28 surrounding pouring spout 26. Shield 28 is sized so that it fits tightly about the outside surface of pouring spout 26. Support shank 29 of pouring spout 26 includes a threaded portion 30 which is positioned immediately below pouring pot l1. lnternally threaded collar 32 is connected to the upper end of shield 28 and threaded onto the threads of pouring spout 26. Collar 32 engages the bottom surface of pouring pot ll, and functions to hold shield 28 on pouring spout 26 and to positively maintain pouring spout 26 in its proper position with respect to pouring pot 11. Fire clay or mortar 31 surrounds shank 29 of spout 26, to seal shank 29 to the opening 16 of pouring pot 11.

The arrangement of H6. 2 is such that the outer surface of pouring spout 26 is shielded and virtually sealed from the atmosphere, so that the outside surface of pouring spout 26 will not oxidize due to oxygen of the atmosphere freely contacting its hot outside surface.

As is best shown in FIG. 3, collar 32 can be modified as collar 34, by positioning aperture 35 in collar 34 so that it communicates with the upper end of pouring spout 26, adjacent the threaded portion 30 of shank 29. Fitting 36 communicates at one of its ends with aperture 35, and at the other end of its ends with conduit 38 which is connected to a source of inert gas under pressure. Shield 28 is sized so as to leave a small annular space 39 between the inside surface of shield 28 and the outside surface of pouring spout 26. Thus, the pressurized inert gas will flow through conduit 38, fitting 36, and aperture 35 to annular space 39, whereupon it surrounds the outside surface of pouring spout 26. The presence of inert gas in annular space 39 is such that the oxygen in this space is removed from the vicinity of pouring spout 26. Thus, no oxygen is present at the outside surface of pouring spout 26 to cause oxidation of the pouring spout.

The stainless steel shields 28 of H05. 2 and 3 are telescoped over the protruding ends of their pouring spouts after the pouring spouts have been inserted into the opening 16 of pouring pots ll. Shields 28 are constructed so that the lower end of a pouring spout protrudes beyond the ends of the shields. Thus, the end portion of the pouring spout will be exposed to the atmosphere, while the upper portion of the pouring spout will be protected. Since the lower end of the pouring spout will dissipate even when a protective shield surrounds this portion of the pouring spout due to oxygen contacting the extreme end of the pouring spout and due to the molten metal flowing through the pouring spout, it is better to allow the lower end of the pouring spout to protrude from the shield, since otherwise the lower end of the pouring spout would be dissipated inside of the shield. Furthermore, it is not detrimental to the pouring function to have a portion of the lower end of the pouring spout foreshortened or dissipated.

in the case where the pouring spout is protected by mortar the mortar can extend down to the lower end of the pouring spout since the mortar will crumble and dissipate with a corresponding dissipation of the pouring spout without detrimental effect on the resulting cast metal.

While the average life span of an unprotected graphite pouring spout is from 2 to 4 hours of pouring time, a pouring spout protected as disclosed herein will survive an average of 8 hours pouring time, with some pouring spouts surviving over 14 hours pouring time. Thus, it should be obvious the invention disclosed herein provides an improved pouring spout for casting molten metal, that the longer life of the pouring spout reduces the cost of construction of the spout and the labor required to replace worn spouts. Furthermore, less down time is experienced in the casting machine.

While the pouring spout has been disclosed as being fabricated of graphite, silicon carbide and clay graphite pouring spouts have been successfully used in continuous casting apparatus, and mortar and stainless steel shields can also be utilized with pouring spouts of this type. Furthermore, it is anticipated that various other materials can be utilized as pouring spouts and to protect pouring spouts. The basic requirement is that the protective material adhere to or be positiona ble closely adjacent the outside surface of the pouring spout to prevent circulation of oxygen adjacent the outer surface of the pouring spout, or that a space be provided between the protective shield and the other surface of the pouring spout to drive oxygen away from the outside surface of the pouring spout.

It will be obvious to those skilled in the art that many variations may be made in the embodiments chosen for the purpose of illustrating the present invention without departing from the scope thereof as defined by the appended claims.

I claim:

1. In a high-temperature molten-metal-casting system, a method of protecting the external surface of an exposed tubular pouring spout of a material oxidizable at said temperature from oxidizing comprising surrounding the pouring spout with a spaced shield and flowing an inert atmosphere between the shield and pouring spout.

2. in combination, a metal pouring pot for high-temperature molten metal and a pouring spout assembly associated therewith, said pouring spout assembly being of a length to guide said metal to a region located a substantial distance from said pot, said pouring spout assembly including an elongated refractory spout of oxidizable material and of generally tubular configuration including an enlarged, tapered support shank at the upper end of the pouring spout, said tapered support shank portion comprising less than half of said length of said pouring spout, and said tapered support shank portion combining with a complementary tapered portion on the pouring pot to give a secure fit between the pouring spout and the pouring pot, a lower portion of said pouring spout assembly being exposed to the atmosphere and comprising over half of the total length of said pouring spout assembly, and a coating of oxidation resistant material situated between said pouring spout and said pouring pot and further extending approximately the entire length of the pouring spout on the exterior thereof, the coating of oxidation resistant material on said lower portion of said spout being of sufficient thickness to comprise means for retarding oxidation damage to the spout.

3. The invention of claim 2, wherein said oxidation resistant material comprises a coating of refractory material applied to the exterior surface of said pouring spout.

4. The invention of claim 2, wherein said oxidation resistant material comprises a stainless steel shield surrounding said pouring spout.

5. A pouring spout assembly for pouring high-temperature molten metal from a pouring pot, said pouring spout assembly including an elongated spout fabricated of a material oxidizable at said temperature and being of tubular configuration, a shield spaced from and generally surrounding said spout, and means for forming a flow of inert gas between said shield and said spout.

6. The pouring spout assembly of claim 5 and wherein said shield comprises a metallic tube surrounding said spout.

7. A pouring spout assembly for pouring high-temperature liquid from a pouring pot, said pouring spout assembly including an elongated graphite spout generally of tubular configuration and further including an enlarged support shank as its upper end for insertion into a pouring pot, said spout protrudditives including ferrous oxide, copper oxide, magnesium oxide and titanium oxide, said mortar being of sufficient thickness to prevent oxidation of the external surface of the protruding portion of said spout.

I I I i F

Claims

7. A pouring spout assembly for pouring high-temperature liquid from a pouring pot, said pouring spout assembly including an elongated graphite spout generally of tubular configuration and further including an enlarged support shank as its upper end for insertion into a pouring pot, said spout protruding in a downward direction from the pouring pot for a distance substantially greater than said enlarged shank portion, and a coating of mortar applied to the exterior downward protruding portion of said spout, said mortar being comprised of a large percentage of silicon dioxide, smaller percentages of aluminum trioxide, lithium oxide and alkaline earth, with additives including ferrous oxide, copper oxide, magnesium oxide and titanium oxide, said mortar being of sufficient thickness to prevent oxidation of the external surface of the protruding portion of said spout.