US3547182A

US3547182A - Continuous casting apparatus

Info

Publication number: US3547182A
Application number: US707236A
Authority: US
Inventors: Robert F Roelofs
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1968-02-21
Filing date: 1968-02-21
Publication date: 1970-12-15
Anticipated expiration: 1987-12-15

Description

United States Patent [72] Inventor Robert F. Roelofs Grosse Pointe Farms, Mich. [211 ApplL'No. 707,236 [22] Filed Feb. 21, 1968 [45] Patented Dec. 15, 1970 [73] Assignee National Steel Corporation a corporation of Delaware [54] CONTINUOUS CASTING APPARATUS 11 Claims, 4 Drawing Figs.

[52] US. Cl 164/281, 249/197,164/53 [51] Int. Cl B22d 11/10 [50] Field otSearch 164/53, 82, 124, 281, 337, 338, 276; 249/62, 200,197,198

[56} References Cited UNITED STATES PATENTS 2,841,843 7/1958 Nouveau 164/338 3,326,273 6/1967 Jago et al 164/53X FOREIGN PATENTS 983,781 2/1951 France 164/82 l884-No 3/1884 Great Britain 164/124 4477 1,002,522 8/1965 Great Britain 164/83 409,925 3/1945 ltaly 164/82 705,902 5/1941 Germany 164/82 Primary Examiner-.1. Spencer Overholser Assistant ExaminerR. Spencer Annear AttorneyShanley and ONeil ABSTRACT: Continuous casting apparatus of the closed pouring type including a tundish removably mounted on the mold. The tundish comprises a refractory conduit into which molten metal is teemed to provide a body ofquiescent molten metal above the mold entry and the cross-sectional areas of the refractory conduit and the mold are generally equal to reduce heat loss. A body of exothermic material surrounds the refractory conduit and the exothermic material is burned during the casting operation to block heat loss from the teemed molten metal.

g, l 30 if PATENTED um 5|97B 354K182 INVENTOR ROBERT F. ROELOFS B M-W ATTORNlz'YS CONTINUOUS CASTING APPARATUS BACKGROUND OF THE INVENTION Continuous casting operations require close control of the temperature of the molten metal entering the mold, especially in the case of specialized products, since the temperature of the metal affects the grain structure of the cast product. Molten metal arrives at the casting operation close to or slightly above the required casting temperature and it is essential for a commercial operation that the molten metal be transferred to the mold with minimum loss of heat in order to maintain the critical casting temperature. Prior continuous casting systems do not adequately meet these requirements especially systems employing oscillating molds and particularly inclined oscillating molds which require the flow of nonturbulent molten metal into the mold. i

The present invention overcomes the foregoing difficulties by the provision of a novel tundish that maybe used with conventional mold structures and has special utility with inclined molds of the oscillating type. The novel tundish comprises a conduit of refractory material adapted to be removably supported by the mold to provide an extension of the entry end-of the mold. The refractory conduit has a cross-sectional area preferably no greater than the cross-sectional area of the mold inlet to provide minimum heat loss and mass, anda sleeve of exothermic material is provided about the refractory conduit that is adapted to be burned during the casting operation to substantially completely block loss of heat from the teemed metal.

Other objects and advantages of the invention will appear from the following detailed description considered in connection with the accompanying drawing which discloses a preferred embodiment of the invention, the drawing being provided for purposes of illustration only.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, in which similar reference characters denote similar elements throughout the several views:

FIG. 1 is a diagrammatic view, partly in section, of continuous casting apparatus embodying the principles of the invention;

F IG. 2 is a view in vertical cross section of a tundish provided by the present invention in combination with an inclined oscillating mold; Y 3

FIG. 3 is a view in section along line 3-3 of FIG. 2; and

FIG. 4 is a view in section along line 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a ladle supported by a ladle crane, not shown, is illustrated teeming a stream of molten metal into a tundish 12. The tundish 12 is constructed in accordance with the principles of the invention and is mounted on the inlet end of a mold l4. Molten metal is at least partially solidified in mold 14 to form a continuous casting 16 which is guided by rollers 18 toward a horizontal path and cooled by spray nozzles 20. From rollers 18, the casting 16 passes through pairs of straightening rollers 22 for delivery to a succeeding processing station, not shown.

As shown more particularly in FIG. 2, the tundish 12 comprises a cylindrical conduit 24 made of refractory material, such as graphite, to withstand the high temperatures involved. The conduit 24 is of cylindrical shape and includes a continuous sidewall 28 terminated at its opposite ends in planes perpendicular to longitudinal axis 26. A flange 32 extends outwardly from the outside surface 30 of the wall 28 and supports the conduit 24 on upper surface 34 of the mold 14 at its entry end. A pair of rapidly operable clamps.36,'shown in FIGS. 3 and 4, fit over opposite portions of flange 32 to secure the tundish 12 to the mold. The clamps may be of any suitable design and, as illustrated, include a bolt 35 rigidly secured to a lug 38 carried by the mold 14 and an apertured plate 37 received by the bolt and maintained in clamping relation with the top surface of the flange 32 by a nut 39. The flange 32 is spaced axially from the lower end of the wall 28 so that the discharge end of the conduit 24'projects a short distance into mold 14, preferably in close contact with the inside mold surfaces, to facilitate alignment of the tundish on the mold. Also, the side wall 28 at the discharge end of the conduit is of increased thickness for increased strength and durability. This construction, with the clamps 36, positively secures the tundish to the mold, prevents the tundish from being buoyed upwardly by molten metal in the mold and prevents escape of molten metal between flange 32 and mold surface 34. Yet, the clamps permit tundishes to be changed quickly with a minimum of caster downtime.

A rigid sleeve 40 of exothermic material surrounds the outside surface 30 of the sidewall 28 of conduit 24. As shown in FIG. 3, the sleeve 40 is formed in two preformed half sections which are fitted around the surface 30 so that the exothermic material is in close heat exchange relationship with side wall 28 throughout its length from the flange 32 to the entry end of conduit 24. The exothermic material is adapted to be burned during a casting operation to establish a heat source between the molten metal and the surrounding atmosphere and effectively block the flow of heat from metal in the tundish to the atmosphere and thereby maintain the molten metal at the required casting temperature. Exothermic-ma'terials that burn at a sufficiently high temperature to materially impede the flow of heat from molten metal within the conduit 24, preferably at a temperature corresponding to the temperature of the molten metal, that burn at a relatively low rate and that may be readily ignited, are suitable for practicing the present invention. An exemplary composition includes, by weight, 30 percent aluminum powder, 5 to 10 percent barium nitrate, 5 percent manganese dioxide, 5 percent iron oxide, 40 to 45 percent aluminum grog to prevent excessively rapid combustion, l to 2 percent aluminum fluoride to provide a relatively low ignition temperature and insure complete combustion, and 3 to 5 percent of a binder such as clay and sulfite lyes.

The mold 14 is of the inclined type of generally rectangular cross section having opposed planar inside

surfaces

42, 43, 44, and 45. The

planar surfaces

42 and 44 intersect the longitudinal axis 26 of the conduit 24 at an acute angle a which may be about 45. The mold 14 is made from copper or other suitable metal of high thermal conductivity and includes a cooling chamber 47 supplied with cooling water through an inlet conduit 46 and an outlet conduit 48. A mounting lug 50 is provided to mount mold 14 on an oscillating device, not shown, which may be of conventional design for reciprocating mold 14 in a direction parallel to the longitudinal axis of the mold as shown by the arrows 52.

The cross-sectional areas of the top and bottom openings of the conduit 24 and the cross-sectional area of the inlet of the mold correspond, i.e., compare closely with one another, to provide minimum surface area in the tundish and thereby reduce heat loss. As shown, the cross-sectional area of the tundish openings can actually be less than. that of the mold. While the respective shapes of the open cross sections of the conduit and mold are illustrated as circular and square, respectively, other shapes may be employed and the conduit may correspond to the shape of the mold.

In one mode of operation, the tundish 12 is clamped to mold l4 and the exothermic material of sleeve 40 is ignited. Molten steel is teemed into the tundish from ladle 10 at a rate to maintain a body of metal in tundish 12. Combustion of the exothermic material minimizes heat loss from molten metal in conduit 24 and the metal enters the mold at the desired casting temperature and in a quiescent state as turbulence caused by the stream of metal falling from ladle 10 is dampened by the pool of metal in tundish 12. When teeming is completed, the burning exothermic material is extinguished, clamps 36 are released, and the remains of tundish 12- are removed. Another tundish is clamped into place on mold 14 and casting can be resumed when desired.

'"Apparatus provided by the invention is highly ad- 'vantageous. The burning of the exothermic material reduces t loss from molten metal in the tundishwithout resort to umbersome electric or fuel-burning heating apparatus and :heat losses are further reduced by providing a tundish of a size comparable to the mold entry dimensions. Mounting of the 'tt'indi'sh on the mold by a rapidly operable clamping arrangeaim makes possible rapid replacement of tundishes and concomitant reduction of caster downtime for tundish repair. Maintenance and other costs associated with refractory-lined inetal tundishes of the prior art are eliminated by use of lightweight, prefabricated ttihdishes which can be quickly is placed with a minimum of casterdowntime, as provided by e present invention. While the tundishes can be expendable that no maintenance is required, if thematerial selected for the conduit 24 permits reuse of the conduit, another exothermic sleeve can be placed around the conduit and the assembly reused. Turbulence of metal entering the continuous casting .nipld is minimized, thereby improving casting quality. This feature of the invention greatly facilitates use of inclined molds, because turbulence generated by a falling stream of metal acting against an inclined mold surface had been a severe disadvantage of inclined molds. Apparatus according to the invention can be employed with horizontal continuous casting molds, by formation of the molten metal discharge opening of the tundish in a sldewall in the lower end portion of theconduit. Furthermore, the novel tundish provided by the present invention has special utilityin connection with closed contained heat generating means to prevent loss of heat from the 'teemed metal eliminates problems that would be associated with the use of prior art heat insulating devices in combination with oscillating molds.

' ,Although the invention has been described in connection with a preferred embodiment, various changes and modifications may be made therein without departing from the principles of the invention. Reference therefore t will be had to the appended claims for a definition of the limits of the invention.

' 21; Continuous casting apparatus, comprising:

P tundish including a conduit having first and second opposite an end portions;

the conduit also having sidewalls of refractory material;

the sidewalls having outside surfaces; I

means defining an opening in the first end portion of the conduit for receiving molten metal;

means defining an opening in the second end portion of the conduit for discharging molten metal;

a mass of exothermic material surrounding and in heat exchange relationship with the outside surfaces of the sidewalls of the conduit;

the exothermic material extending. a substantial distance along the sidewalls;

,a continuous casting mold;

mounting means for removably mounting the tundish in a position on the mold for discharging molten metal into the mold; and I the mounting means including rapidly operable means for releasably securing the tundish in the position.

2. The apparatus of claim 1, the mounting means including supporting means associated with the tundish and extending radially outwardly relative to the conduit, for supporting the tundish on the mold.

3. The apparatus of claim 1, the tundish including means for aligning the tundish in the position.

4. The apparatus of claim 1, the rapidly operable means including means for clamping the tundish to the mold.

5. The apparatus of claim 2, the supporting means comprisingia flange adjacent the second end portion of the conduit.

. The apparatus of claim 5, the exothermic material extending along the sidewalls from the flange to the opening in the first end portion of the conduit.

7. The apparatus of claim 1, the second end portion of the conduit including means projecting a short distance into the mold for aligning the tundish in the position.

8. The apparatus of claim 1, the mass of exothermic material comprising a rigid sleeve.

9. The apparatus of claim 1, the conduit having a longitudinal axis extending in a generally vertical direction, the mold including an inside surface intersecting the axis of the conduit at an acute angle.

10. The apparatus of claim 1, the conduit and the mold having open cross-sectional areas, the open cross-sectional area of the conduit being less then the open cross-sectional area of the mold.

11. The apparatus of claim 1, including means for mounting the mold for reciprocating movement.

zg ggg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,547,182 Dated December 15, 1970 Inventor(s) Robert F. Roelofs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 15, change "to" to -so-.

Column 3, line 26, change "sldewa 11" to -side wall-.

Column 3, line 41, delete "t" after "therefore.

Column 3, line 44, cancel the colon Column 3, lines 45-46, cancel "a conduit having first and second opposite an end portions; and insert the follov ing in subparagraph form: -a conduit having first and second opposite end portions,.

Column 4, line 1, change the semicolon Column 4, line 2, change the semicolon Column 4, line- 4, change the semicolon Column 4, line 6, change the semicolon to and-.

Column 4, line 9, change the semicolon to a comma Column 4, line 12, after "mold; insert --and-.

Column 4, line 15, change "7 and" to a comma Column 4, lines 37-39, the present recitation of "the mold including an inside surface intersecting the axis of the conduit at an acute angle. constitutes a separate subparagraph and should be inserted in subparaph form after "direction, in line 37.

Column 4, lines 41-43, the present recitation of "the open cross-sectional area of the conduit being less than th' open cross-sectional area of the mold. constitutes a separate subparagraph and should be inserted in subpara graph from after "areas in line 41.

to a comma to a comma to a comma Signed and sealed this 30th day of March 1971.

(SEAL) Attest:

EDWARD M.FI.ETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents