US 3521698 A
Description (OCR text may contain errors)
July 28; 1970 P. COLOMBO APPARATUS FOR THE CONTINUOUS CASTING OF FLAT BLOOMS Filed Jan. 26, 1968 INVENTOR COL OMB 0,
M 'z I m f 11; Y.
P/EEO United States Patent Int. Cl: B22d 11/10 US. Cl. 164-281 3 Claims ABSTRACT OF THE DISCLOSURE In a flat blooms continuous casting plant, the tundish is mounted so as to be reciprocated with respect to the underlying open ended mold in the direction of the major sides of said mold. Means are provided for reciprocating the tundish during the casting of the molten metal into the mold.
This invention relates to the continuous casting of metals, and more particularly to an apparatus for the continuous casting of flat steel blooms.
In the continuous casting of metals in form of flat blooms a main problem 'arises connected with the difliculty of obtaining an even distribution of the temperatures inside the continuous casting mold, particularly in the direction of the longer sides of the cross-section of the bloom. -In fact, it is known that in the continuous casting of metals, the mold, which is open ended, is fed with the liquid metal from a fixed tundish, disposed above the mold and provided at its bottom with one or more pouring nozzles from which the molten metal flows from the tundish into the mold. As a consequence, in the known continuous fiat blooms casting apparatus the streams of molten metal from the tundish are always flowing towards fixed locations inside the mold, thus giving rise to an uneven distribution of the temperatures inside the ascast bloom, with overheated zones in correspondence of the pouring nozzles and particularly along the long sides of the bloom itself.
On the other hand, it is not possible to obviate to the said disadvantage by increasing the number of the pouring nozzles, or by decreasing the mutual distance between the said nozzles, as it would be prima facie obvious, because of the fact that the number of allowable nozzles and/or the interdistance between contiguous nozzles are a function of other parameters of the said apparatus and cannot be varied at will, as it is well known to any person skilled in the art to which the present invention appertains.
The said uneveness in the temperatures distribution, which are as more appreciated as greater the ratio between the long and short sides of the cross section of the fiat bloom is, give rise to crackings on the surface of the fiat bloom. The side cracks formation is particularly evident whenever steels having a low thermal conductance and a low yield point at high temperatures are cast.
Moreover, the said localized hot zones may also conduct to the burst of the skin of the cast bloom, with consequent escape of molten metal from the core of the bloom, or to bulking of the bloom sides, by effect of the ironstatic pressure acting on the hot zones of the bloom skin.
It is therefore the main object of the present invention to obviate to the above mentioned disadvantages of the known fiat blooms casting apparatus.
According to the present invention, the above object is accomplished by reciprocably mounting the tundish in a substantially horizontal plane, so as to effect a to and fro movement in the direction parallel to the direction of the longer sides of the underlying open ended casting mold, means being provided for reciprocating the tundish during the casting operation.
By the said arrangement, the position of the molten metal streams issuing from the pouring nozzles at the bottom of the tundish varies, during the casting operation, continuously along the direction of the reciprocating movement of the tundish, and thus parallel to the long sides of the mold. In this manner, by suitably selecting the amplitude and the frequency of the said reciprocating movement with respect to the number and the interdistance of the pouring nozzles at the tundish bottom, and with respect to the cross sectional dimensions of the flat bloom which is being cast, a substantially even distribution of the temperatures in the cast bloom is obtained, thus obviating to the above mentioned drawbacks.
The above and other objects and advantages of the present invention will be better apparent from the following specification, made with reference to the accompanying drawing, in which:
FIG. 1 is a schematic partially sectioned side view of the reciprocating tundish according to the invention, with the associated mold and ladle of a continuous metal casting plant, and
FIG. 2 is a top plan view of the open ended mold of the plant of FIG. 1.
In the drawings, 1 generally denotes the open ended mold of a continuous metal casting plant of conventional construction. The said mold 1 is mounted in conventional manner on a platform 2 so as to be reciprocated in a substantially vertical plane, in the directions of the double arrow 3. The mold 1 is further provided with a jacket 4 through which a cooling fluid is continuously circulated through pipes 5. In the embodiment as shown in FIG. 2, the mold 1 is of rectangular cross section in plan view, for the continuous casting of so-called flat blooms, that is of blooms have a substantially rectangular or otherwise elongated cross section, with two opposite sides of a length substantially greater than the length of the remaining two sides. 6 denotes a pair of conventional bloom or ingot guide rolls, mounted below mold 1 along the path of the cast flat bloom 7.
Above mold 1 the tundish 8 is mounted, which is supported on a movable frame 9, straddling the mold 1 and provided with supporting legs 10, provided at their lower ends with wheels 11, rolling on horizontal tracks 12 supported by the fixed frame (not shown) and extending in the direction of the longer sides of the mold 1.
The tundish 8, as shown in the drawing, comprises an outer shell 81 of sheet metal, comprising side walls and a bottom wall. The sheet metal Walls are reinforced with intermediate heavy steel plates 82, upon which an inner lining made of refractory material slabs 83 is fitted, covering the sides and the bottom of the tundish 8. On the bottom of the tundish 8 a pair of pouring nozzles 13 are mounted, through which the molten metal from tundish 8 flows into the underlying mold 1. Above the tundish 8, the molten metal pouring ladle 14 is suspended, in conventional manner.
In correspondence of one of the smaller sides of the tundish-supporting frame 9, between a pair of lugs 16 connected to one of the legs 10 of said frame a connecting rod 15 is hinged by one of its ends. The other end of said connecting rod 15 is hinged to a crankpin 17 fited onto the fly wheel 18 keyed on the output shaft 19 of a speeddown gear 20, the input shaft of which is driven by a suitable motor (not shown).
The operation of the just described apparatus is as follows:
When the molten metal has been poured from the ladle 14 into the tundish 8, by rotating the wheel 18, through crankpin 17 and connecting rod 15 the frame 9 is slowly reciprocated on rails 12 and the tundish 8 is reciprocated over the mold 1 in the direction of arrows 21, that is in the longitudinal direction of the said mold 1. By this horizontal reciprocating movement, the molten metal, in the tundish 8, flows out through nozzles 13 into the underlying vertically reciprocated mold 1 substantially along its Whole length, thus avoiding the formation of hot pouring zones in said mold and producing a practically homogeneous flat bloom, which is cast from the underside of the mold 1.
It is thus apparent that by the above arrangement the mentioned drawbacks connected with the continuous casting of fiat blooms are obviated.
Having thus fully described my invention with reference to a preferred embodiment thereof, what I claim as new is:
1. A continuous metal casting apparatus for the continuous casting of fiat blooms, comprising a fixed supporting frame, an open ended mold carried by said fixed frame, a tundish supported by said fixed frame and disposed above said mold, and pouring nozzles in the bottom of said tundish for pouring the molten metal from said tundish into said mold; the improvement consisting in supporting said tundish movable toand-fro in a substantial horizontal direction above said mold, and automatic means for continuously reciprocating said tundish during metal pour so as to cause its pouring nozzles to reciprocate above said mold cavity on longitudinal paths substantially parallel to the major axis of the cross section of the flat bloom being cast in such a manner that a substantially even distribution of temperatures in the cast bloom is obtained.
2. A continuous metal casting apparatus for the continuous casting of fiat blooms comprising a supporting frame, a mold platform, a vertical gravity flow open ended mold on said platform; said mold being provided with two parallel sides of a greater length than the length of the remaining two sides; guide rails on said frame extending in a horizontal plane and in a direction which is substantially parallel to the direction of the said longer sides of the said mold; a wheeled frame on said rails supported for a movement along said mold; a tundish on said frame above said mold; pouring nozzles in the bottom of said tundish; and operating means connected to said tundish supporting frame for reciprocating said frame and tundish above said mold along said guide rails.
3. A continuous casting plant according to claim 2 in which said operating means comprise a crank and connecting rod transmission, said connecting rod being hinged by one end to the crankpin and by its opposite end to said wheeled frame.
References Gited UNITED STATES PATENTS 612,610 10/1898 Levy 164-136 3,456,713 7/1969 Michelson 164-82 1,298,036 3/1919 Gathmann 164135 2,732,601 1/1956 Junghans 16482 3,375,862 4/1968 Boitchenko et al. 164-281 X 3,435,879 4/1969 Greenberger 16483 FOREIGN PATENTS 515,243 8/1955 Canada.
I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner US. Cl. X.R. 164-136