US3604598A - Outlet passage construction for teeming vessels - Google Patents

Abstract

A bottom pour-teeming vessel in which the walls of the outlet passage are equipped with an electric-heating coil. The passage walls may be formed of a zirconia or 90 percent alumina liner and a sleeve surrounding the liner but spaced radially therefrom. The heating coil winds about the liner in the space between it and the sleeve and the remainder of the space is filled with alumina powder. A layer of thermal insulation encloses the sleeve. The sleeve is supported on a refractory nut threaded on the lower end of the liner.

Description

United States Patet Keith K. Kappmeyer Franklin Township, Westrnoreland County; James T. Shapland, Wilkins, Township,

[72] Inventors Allegheny County, both of Pa. [21] AppLNo. 840,215 [22] Filed July 9, 1969 [45] Patented Sept. 14, 1971 [73] Assignee United States Steel Corporation Continuation-impart of application Ser. No. 698,514, Jan. 17, 1968, now abandoned.

[54] OUTLET PASSAGE CONSTRUCTION FOR TEEMING VESSELS 5 Claims, 7 Drawing Figs.

[52] 0.8. CI 222/146, 164/281 [51] Int. Cl 865d 5/62 [50] Field of Search 222/146 HE, l46;239/l33; 164/337, 119, 133;219/28l, 10.49, 10.51; 266/38; 13/33 [56] References Cited UNITED STATES PATENTS 1,763,229 6/1930 Fourment 2l9/10.5l X 2,324,337 7/1943 Jomsland 222/146 X 3,028,874 4/1962 Burkett 266/38 X 3,367,646 2/1968 Robertson et al... 266/38 X 3,435,992 4/1969 Tisdale et al 164/281 X 3,427,421 2/1969 Matheson et al. 219/1099 3,501,068 3/1970 Shapland 222/561 X Primary Examiner- Sam uel F. Coleman A ssigqnt Examiner- Norman L. Stack, J r. Attorney-Walter P. Wood ABSTRACT: A bottom pour-teeming vessel in which the walls of the outlet passage are equipped with an electric-heating coil. The passage walls may be formed of a zirconia or 90 percent alumina liner and a sleeve surrounding the liner but spaced radially therefrom. The heating coil winds about the liner in the space between it and the sleeve and the remainder of the space is filled with alumina powder. A layer of thermal insulation encloses the sleeve. The sleeve is supported on a refractory nut threaded on the lower end of the liner.

PATENTED SEP 1 4 I97: 3,604 598 sum 1 [1F 3 TIE-.1...

HI HH H' INVENTORS. 9 KEITH KKAPPMEYERE JAMES T. .SHAPLAND A t I may PATENTEU SEP1 4mm 3.604.598

snw 2 OF 3 INVENTORS. 23 24 KEITH K. KAPPMEYER a JAMES T. SHAPLAND o- -F J I J- 7 OUTLET PASSAGE CONSTRUCTION FOR TEEMING VESSELS This application is a continuation-in-part of our earlier application ser. No. 698,514, filed Jan. 17, 1968, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an outlet passage construction for discharging a stream of molten metal from a teeming vessel such as a tundish.

In the continuous casting of steel, it is desirable to teem metal into the conventional tubular flow-through mold at a temperature close to the solidification point so that, on initial contact with the mold wall, the metal cools sufficiently to solidify and form a skin on the casting. It has been the practice to have outlet passages of small bore in the tundish from which metal is teemed into the mold in order to facilitate close control of the volume of flow. As a result of both these factors, there is a tendency for the metal to freeze in the bore and restrict further flow therethrough. Wear of the conventional fire-clay nozzle in use results in an uncontrolled increase in the size thereof as well as introducing nonmetallic inclusions into the casting. An object of our invention is to provide a teeming-vessel nozzle or partially submerged pouring tube which is wear-resistant and has built-in heating means to limit the freezing tendency of the metal teemed therethrough.

SUMMARY OF THE INVENTION In a present preferred embodiment of our invention, we provide a nozzle having a wear-resistant liner, a thermally insulating exterior sleeve surrounding the liner with a cylindrical space therebetween and an electric-resistance heating coil positioned in said space and embedded in refractory material which is both thermally and electrically insulating. The liner is preferably of high-alumina refractory, i.e., 90 percent A or zirconia. The sleeve is of alumina or graphite and is surrounded by a layer of thermal insulation. The coil is of graphite and the material embedding the coil is alumina powder. In a modification we provide a similar arrangement in a partially submerged pouring tube.

BRIEF DESCRIPTION OF THE INVENTION A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

FIG. 1 is an axial section through one form of our invention;

FIG. 2 is a similar view of a modification;

FIGS. 3 and 4 similarly show further modifications;

FIG. 5 is a developed view of the heating coil of the form of the invention shown in FIG. 1;

FIG. 6 is an axial section showing another modification in which our invention is applied to a partially submerged pouring tube; and

FIG. 7 is a horizontal section on line VIIVII of FIG. 1.

DETAlLED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the drawings and, for the present, particularly to FIG. 1, a teeming vessel 10, such as a tundish,

has a bottom outlet passage construction indicated generally at 11. The outlet passage is built into the lining 12 of the vessel which is enclosed within a shell 13 of steel plate. More specifically, the walls of the outlet passage include a tubular metal neck 14 having a layer 15 of castable thermally insulating material of any known kind, usually fire clay, which extends I It up into the vessel lining 11. neck 14 is supported Neck shell 13 by bolts 16.

The interior of the passage is formed of a nozzle liner 17 of end shaped to form a seat 18a for the lower end of the conven tional stopper rod (not shown). As shown, block 18 is embedded in the vessel lining l2 and a nut 19, also of the same material, is threaded on the lower end of liner 17. A continw ous bore 20 extends through block 18 and liner 17 to conduct molten metal from vessel 10 to a mold therebelow.

A sleeve 21 of the same material as liner 17 extends between nut 19 and block 18, surrounding liner 17 with a space therebetween. In this space is disposed a heating coil 22 having terminals brought out at 23 and 24 through alumina tubes 25. The terminals extend radially through sleeve 21, insulation layer 15 and neck 14 from separate semicircular segments 26 of graphite (FIG. 7). Coil 22 is a doubled helix of graphite, the developed form of which is a loop L shown in FIG. 5. The coil and segments 26 may readily be formed by machining a cylinder molded from graphite. The space between liner l7 and sleeve 21 is filled with powdered alumina 27 after insertion of coil 22 and segments 26, Provision may be made as shown at 28 for water- cooling terminals 23 and 24.

Coil 22 is energized, before metal is to be teemed, as an electrical-resistance heater, by alternating or direct current of high amperage. When so energized, the heat conducted to any skull or metal frozen on the surface of bore 20 will tend to melt or, in any event, prevent building up of the skull to an objectionable extent. The material of which liner 17, block 18 and sleeve 21 are composed, i.e., zirconia or 90 percent alumina, is well suited to withstand both the temperature of molten metal passing therethrough and the erosive action of the stream.

FIG. 2 shows a modification. In this form of our invention, coil 22 has upper and lower sections connected in parallel to segments 26. In addition, inner sleeve 29 of the same material as sleeve 21 is interposed between coil 22 and liner 17. This construction permits liner 17 to be replaced without removing coil 22 from its mounting between sleeves 21 and 29.

FIG. 3 shows a further modification in which the segments 26 of FIG. 1 are near the top of the spout. Semicylindrical segments 30 of graphite take the place of sleeve 21 and also serve as conductors between terminals 23 and 24 an segments 26. Radial conductors 31 of graphite connect segments 30 and 26.

FIG. 4 shows a further modification in which segments 26 are above the coil 22. In lieu of terminal 24, furthermore, one end of the coil is grounded on shell 13 as at 32.

It will be evident that the modification of FIGS. 2-4 have all the advantages of the construction of FIG. 1.

FIG. 6 shows portions of a conventional nozzle and receiving vessel 42, which is shown as a mold, either an openended mold used in continuous casting or an ingot mold, but it may be some other type of vessel. The nozzle forms part of a pouring vessel from which is suspended a pouring tube 43 constructed in accordance with our invention. The pouring vessel supplies molten metal M, which is conducted through the nozzle and tube into the receiving vessel. As known in the art, the discharge end of the tube is submerged in liquid in the receiving vessel, whereby air is excluded from the metal as it flows between the nozzle and receiving vessel.

In accordance with our invention, tube 43 comprises a refractory liner 44, a sleeve formed of upper and lower refractory sections 45 and 46 around the liner and a metal neck 47 around the upper sleeve section. The upper sleeve section 45 has upper and lower counterbores 48 and 49. The lower counterbore 49 has internal screw threads which engage external threads on the lower sleeve section 46. We mortar the threaded joint between the two sections. The upper end of neck 47 has an external flange 50 which we fasten to the tube suspending means. The lower end of sleeve section 46 has an internal flange 51 which we mortar to the liner 44 to prevent liquid metal from entering the lower end of the sleeve.

We place an electric-resistance heating coil 22 in the space between the liner 44 and the lower sleeve section 46. The coil is of similar construction to that used in the embodiments of FIGS. 1 to 4. It has terminals 23 and 24 which extend radially through the upper sleeve section 45 from semicircular segments 26 of graphite. The segments are longer than those used in the other embodiments, since the pouring tube is longer than the nozzle, but otherwise similar. Coil 22 is located where it extends below the surface of liquid in the receiving vessel 42; hence it prevents freezing of metal both inside and outside the pouring tube.

We are aware that it is known to employ induction heating coils around outlets from teeming vessels or the like, but this arrangement requires that the interior of the outlet contains solid metal. Our electric-resistance heating coil is effective for outlets, the interior walls of which are exclusively of refractory material.

We claim:

I. An outlet passage construction for a bottom pour teeming vessel comprising an exclusively refractory liner extending downwardly form the vessel bottom, an electric-resistance heating coil around said liner, said coil being formed of a double helix of graphite, the developed form of which is a loop, semicircular graphite segments integral with the respective helices of said coil, terminals extending radially from said segments, and a refractory sleeve surrounding said coil.

2. A construction as defined in claim 1 comprising in addition a filling of powdered refractory material within said sleeve embedding said coil.

3. A nozzle constructed as defined in claim 1 and comprising in addition a block integral with said liner adapted to be embedded in the refractory lining of the vessel.

4. An extended pouring tube constructed as defined in claim 1, said sleeve being formed of upper and lower threadedly connected sections.

5. A construction as defined in claim 1 in which said coil is machined from a molded graphite cylinder.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.- 559 Dated September- 1 4, 1971 lnventofls) Keith K. Kappmeyer et 8.1

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 71, after "11.", "neck" should read Neck after "supported", "Neck" should read from Column 2, line 13, "doubled" should read double Column 2, line ho, "an" should read and Signed and sealed this 10th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC DOING-POD v u s eovimmim wnlrnmu OFFICE Ins o-zss-Ju.

RM PO-IOSO (10-69)

Claims (5)

1. An outlet passage construction for a bottom pour teeming vessel comprising an exclusively refractory liner extending downwardly form the vessel bottom, an electric-resistance heating coil around said liner, said coil being formed of a double helix of graphite, the developed form of which is a loop, semicircular graphite segments integral with the respective helices of said coil, terminals extending radially from said segments, and a refractory sleeve surrounding said coil.

2. A construction as defined in claim 1 comprising in addition a filling of powdered refractory material within said sleeve embedding said coil.

3. A nozzle constructed as defined in claim 1 and comprising in addition a block integral with said liner adapted to be embedded in the refractory lining of the vessel.

4. An extended pouring tube constructed as defined in claim 1, said sleeve being formed of upper and lower threadedly connected sections.

5. A construction as defined in claim 1 in which said coil is machined from a molded graphite cylinder.

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