US3179989A - Continuous casting mold - Google Patents

Description

April 27, 1965 J. N. HoRNAK CONTINUOUS CASTING MOLD Filed March l, 1962 HHMWIHHHHHWMHMWHHIIIIHHHM NVENTOR. JOHN N. HORN( By United States Patent O 3,179,989 CGNTINUOUS CASTING MOLD .lohn N. Hornalr, Homestead Park, Pa., assigner to United States Steel Corporation, a corporation of New Jersey Filed Mar. 1, 1962, Ser. No. 176,641 Claims. (Cl. 22-57.2)

This invention relates to the continuous casting of a billet or slab of indefinite length by pouring molten metal through a tubular mold and, in particular, to an improved mold for such operation.

Diiculty has been encountered in continuous casting, particularly in the case of slabs having a width several times their thickness, because of breakouts through the skin of the casting after it has emerged from the bottom of the mold. These breakouts are apparently caused in the following manner. Crusts or skulls are formed on top of the mold adjacent the mid-point of the slab width by unavoidable spittings, splashing or divergence of the stream of molten metal descending into the mold from the nozzle of the teeming ladle thereabove. Any such accumulation is quickly frozen on the top edge of the mold which is water-cooled, and remains fixed there until manually removed, customarily upon a shut-down of the casting facilities. If, before removal, these crusts or skulls grow sufficiently to extend downwardly into the mold, the molten metal therein will, if it rises to a high level, tend to weld to the crusts as it solidilies, causing tears in the skin of the slab being cast which eventually result in breakouts.

I have invented a novel mold for continuous casting having means for preventing the difficulty caused by the aforementioned accumulation of crusts or skulls on top of the mold. Such means preferably comprises angle bars reciprocable along the longer sides of the top of the mold and means for actuating them slowly but contin uously during the pouring operation. The bars receive the spittings or droplets of molten metal which would otherwise be deposited on top of the mold and movement of the bars distributes the accumulation, preventing the formation of sizable crusts or skulls.

A complete understanding of the invention may be obtained from the following detailed description and eX- planation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

FIGURE 1 is a plan view of a continuous-casting mold having my invention applied thereto;

FIGURE 2 is a side elevation of a portion of FIGURE 1;

FIGURE 3 is a plan View of the mold having the invention applied thereto, to enlarged scale with parts omitted; and

FIGURE 4 is a partial section through the mold, taken on the plane of line IV-IV of FIGURE 3, showing the ladle nozzle thereabove.

Referring now in detail to the drawing, a tubular mold has sides 11 and ends 12 of double-wall construction for the circulation therethrough of cooling water by suiti forms on the casting as a result of freezi-ng of the metal in contact with the cooled mold walls and increases in thickness as the casting descends through the mold.

The mold ,as described above is conventional. My improvement consists in the combination therewith of shielding bars 18 slidable along the longer sides of the top 13 of the mold. The bars are preferably of angle section and one ange thereof extends downwardly into cavity 14 for a short distance while the other rides llatwise on top 13. The latter is provided with keepers 19 and the bars shaped to interft with them to afford guided movement of the bars and retain them in proper relation to the mold side walls 11.

The means for reciprocating bars 18 along the top of the side walls 11 of the mold comprise a connecting rod in the form of a fork 20 the tines 21 of which are bent at right angles and pivoted to clevises 22 on the bars adjacent one end thereof. The shank 23 of the fork is pivoted to a crank pin 24 in a disc 25. The disc is mounted on a shaft 26 journaled in bearings 27. A motor 28 suitably mounted drives a wonn 29 meshing with a worm wheel 30 on shaft 26. Thus energization of motor 28 causes continuous reciprocation of Ibars 18 at a low frequency, say ten strokes per minute.

It will be evident that the bars 1S shield the side edges of the top of the mold cavity from scabs of metal which would otherwise be formed thereon by splashing or divergence of the molten stream. Movement of the bars distributes the deposits and prevents their accumula tion to an extent such that crusts or skulls would result, which might run downwardly into the mold cavity, with the possibility of tearing the skin 17 of the slab being cast.

The invention acts in three ways to prevent this from happening. First, the overhanging n, if one is formed, is shorter and thinner, and is thus less likely to form a weld of suliicient strength to cause a serious tear in the ingot skin. This results because, with the invention, the spatter from the ladle nozzle is distributed over a greater area, i.e., all along the bar 18 instead of merely in the small area never uncovered by bar 18 as it travels back and forth. Second, the overhanging lin does not line up directly with the skin of the ingot being formed, since any fin formed depends from the bar 18 and not from the edge of the mold. Instead of being in alinement with the ingot skin, furthermore, the fin depends into molten metal. Third, the continuous reciprocation of the bars 18 ensures that, if Welding should begin, the Weld is immediately broken, before it has time to attain the thickness and strength that would make it a possible cause of a tear in the ingot skin sufliciently serious to cause a breakout.

The invention has the advantage of being both simple as to structure and effective as to performance.

Although I have disclosed herein the preferred embodiment of my invention, I intend to cover as Well any change or modification therein which may be made without departing from the spirit and scope of the invention.

I claim:

1. The combination with a tubular continuous-casting mold rectangular in cross-section, having pairs of opposed side walls, of a shielding bar slidable along the top of at least one of said walls, and means for sliding said bar along one of said walls.

2. The combination dened in claim l, characterized by said shielding bar being of angle section with one flange extending downwardly into said mold.

3. The combination defined in claim l, characterized 3 fi by said means including crank means and a connecting References Cited by the Examiner rod pivotally connected thereto and to said shielding bar. UNITED STATES PATENTS 4. The combination defined in claim 1, characterized by a way on said top of one of said walls guiding move- 2503819 4/50 Gimn et al 22-'200'1 XR ment of said shielding bar therealong r 2871530 2/59 Wieland 22-57'2 a 2,905,989 9/59 Black 22-57.3

5. The combination de-ned in claim 1, characterized lby said bar-sliding means including means for reciprocat- MICHAEL V BRINDISI, Pflmly Examinering said shielding bar. RAY K. WINDHAM, Examiner.

Claims (1)

1. THE COMBINATION WITH A TUBULAR CONTINUOUS-CASTING MOLD RECTANGULAR IN CROSS-SECTION, HAVING PAIRS OF OPPOSED SIDE WALLS, OF A SHIELDING BAR SLIDABLE ALONG THE TOP OF AT LEAST ONE OF SAID WALLS, AND MEANS FOR SLIDING SAID BAR ALONG ONE OF SAID WALLS.

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