US3354941A - Continuous direct chill-type casting unit - Google Patents

Description

Nov. 28, 1967 F. E. HALSTEAD CONTINUOUS DIRECT CHILL-TYPE CASTING UNIT Filed May 24, 1965 INVENTOR Fred E. Holstead his Attorney United States Patent ()fiice 3,354,941 CONTINUOUS DIRECT CHILL-TYPE CASTING UNIT Fred E. Halstead, Rochester, Paz, assignor to Halstead Metal Products, Inc., Zelienople, Pa., a corporation of Pennsylvania I v Filed May 24, 1965, Ser. No. 458,135 3 Claims. (Cl. 164-483) ABSTRACT on THE DISCLOSURE This invention relates to improvements incontinuous casting apparatus, arid more particularly to improvements in means for cooling a continuously cast ingot to effect complete solidification of the ingot.

While not limited thereto, the present invention is particularly adapted for use with a continuous direct chill-type casting unit. In such a device, molten metal is poured into a water cooled mold to provide a continuous ingot. As the ingot passes through the mold, only its outer skin is completely solidified; and in order to effect complete solidification throughout its cross section, the ingot passes through a cooling liquid contained within a tank beneath the mold, and thence through an opening in the bottom of the tank. The solidifying ingot is continuously pulled downwardly by pinch rolls beneath the tank and finally cut into lengths by a cut-off saw, also located beneath the tank.

It will be appreciated that it is necessary to provide some type of seal around the opening in the bottom of the tank containing the cooling liquid in order to prevent the excessive escape of liquid therefrom. Otherwise, rather large amounts of liquid will drain down onto the cut-off saw and surrounding area and possibly damage the saw and associated equipment.

Contrary to what might be expected, the provision of a suitable seal for such applications presents a number of formidable problems. First of all, in direct chill-type billet casting machines, it is impossible to achieve I a uniformly smooth, dimensionally accurate, and perfectly straight ingot. This is due to a number of reasons; however it is mainly due to non-uniform cooling which causes the ingot to become slightly non-uniform in cross section and possibly have a slight bow along its longitudinal axis. These two variables, plus the possibility of the ingot having a relatively rough outside surface, make it almost impossible, utilizing normal fixed lip-type sealing members, to maintain a suitable seal around the cast ingot as it comes out of the water cooling tank.

Accordingly, as an overall object, the present invention seeks to provide new and improved sealing means around a continuously cast ingot as it emerges through an opening in the bottom of a cooling tank.

More specifically, an object of the invention is to provide sealing means for a continuously cast ingot as it passes through the bottom of a cooling tank, which sealing means will compensate for any nonlinearity and surface imperfections in the cast ingot.

Briefly, in accordance with the invention, an annular flexible bellows is secured around the opening in the bottom of a cooling tank through which a continuously cast ingot passes. Carried on the lower end of the bellows is an annular guide bushing which surrounds, but does not contact, the downwardly-moving ingot. With this arrangement, the flexible bellows will allow the guide bushing to follow the cast ingot as it emerges from the tank and automatically compensate for any nonlinearity in the ingot; however, the bellows and guide bushing, in

3,354,941 Patented Nov. 28, 1967 and of themselves, will not prevent the escape of liquid from the tank. Accordingly, directly beneath the guide bushing is a seal which, in the preferred embodiment of the invention, comprises spaced upper and lower lip-type seals separated by an annular plenum chamber. By introducing air under pressure into the plenum chamber, the air will pass through any space between the seals and the cast ingot to prevent excessive escape of liquid from the tank, and this regardless of any wear on the seals, nonlinearity in the ingot, or other effects.

, The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIGURE 1 is a schematic illustration of a continuous casting unit incorporating the improved sealing means of the invention; and

FIG. 2 is, a cross-sectional view illustrating the improved sealing means per se. 7

With reference now to the drawings, and particularly to FIG. 1, a continuous direct chill-type casting unit is schematically shown and includes a pouring trough 10 which receives molten metal, such as copper, from a l-adle 12. The pouring trough 10 directs the molten metal into a water cooled mold, generally indicated at 14, and having inlet and outlet connections 13 and 15, respectively. When the molten metal contacts the cooler inner surfaces of the mold 14, a skin is formed defining the outer periphery of a continuousingot 16. That is, the mold 14 will ordinarily cool only an outer annular layer of the molten metal, the inner core of the metal being molten as it passes from the bottom of the mold 14. In order to completely solidify the ingot 16 throughout its cross section, a cooling tank 18 is provided having a cooling liquid 20 therein. As shown, the ingot passes through the liquid 20 and thence through an opening 22 in the bottom of tank 18. The ingot is continuously pulled downwardly by means of pinch rolls 24 driven by motor means, not shown. Finally, the continuous ingot 16 is cut to lengths 26 by means of a cut-off saw, generally indicated at 28, which can reciprocate toward and away from the ingot 16 along the direction of arrow 29 to effect a cutting operation, and which also travels vertically along the direction of arrow 30 in synchronismwith the vertical drop speed of the ingot 16.

As was explained above, a persistent problem with casting units of the type shown in FIG. 1 has been the escape of liquid from the opening 22 in tank 18. This liquid will, of course, drain down onto the saw 28 and surrounding area, causing a messy and unsightly condition and possible damage to the saw itself and associated apparatus. The problem is aggravated by the fact that the ingot 16 is oftentimes nonlinear and bowed due to uneven cooling effects. While attempts have been made to provide seals around the opening 22, such seals were ordinarily of the fixed lip-type. Consequently, due to bowing and nonlinearity in the ingot 16, as well as the inherent roughness of the surface of the ingot, the seals would rapidly wear and excessive amounts of liquid would drain down onto-the saw 28 and surrounding area.

The sealing means of the present invention is shown in FIG. 2 and comprises a flexible metal bellows 34 having radially-outwardly extending flanges 36 and 38 at its upper and lower ends, respectively. The upper flange 36 is bolted or otherwise securely fastened to an annular plate 40 welded to the bottom of tank 18 and surrounding the opening 22. The lower flange 38, on the other-hand, is bolted or otherwise securely fastened to an annular guide bushing 42, the arrangement being such that the metal bellows 34 will permit the bushing 42 to move in a horizontal plane to a limited extent.

Seated against the lower surface of the guide bushing 42 is a first lip-type annular seal 44 which is sandwiched between the lower surface of the guide bushing and an upper flange 46 of an annular spacer 48. As shown, bolts or other suitable fastening means pass through the flange 46 and the seal 44 into the lower surface of the guide bushing 42 to hold all parts in assembled relationship. A second lip-type seal 50 is secured between a lower flange 52 on the annular spacer 48 and a ring 54. The parts being held in assembled relationship by means of circumferentially spaced bolts as shown.

The annular spacer 48 forms a plenum chamber 56 between the seals 44 and 50 and is provided with an inlet port connected through conduit 58 to a source of air under pressure, not shown. When air pressure is introduced into the plenum chamber 56, it will, of course, pass through the space between seal 50 and the periphery of billet 16 into the atmosphere. It will also pass upwardly through the space between the inner periphery of seal 44 and the periphery of the ingot 16. The force of the air is sufficient to prevent any substantial amount of liquid from passing downwardly into the plenum chamber and thence pass the seal 50. Thus, the primary sealing member is the seal 44; whereas the seal 50 serves essentially as a means for confining the air under pressure within the chamber 56.

As the seals 44 and 50 wear, the annular spaces between the seals and the ingot 16 will, of course, become larger. However, the air will still prevent the excessive escape of liquid, the essential difference being that as the seal 44 wears, more air will bubble upwardly through the liquid in tank 18. At the same time, due to the flexible nature of the bellows 34, the entire assembly comprising the guide bushing 42, seals 44 and 50, and the annular spacer 48 can. move laterally to accommodate any nonlinearity or change in position of the longitudinal axis of the ingot 16.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In continuous casting apparatus of the type in which a continuously cast ingot traveling in a vertically downward direction passes through a tank having a cooling liquid therein and thence through an opening in the bottom of the tank, the improvement in means for preventing the substantial escape of liquid through said opening in the tank comprising a guide bushing surrounding the ingot below the opening in the tank, an annular flexible bellows interconnecting the guide bushing and the tank to form a cavity communicating with said tank, seal means carried on the lower end of said guide bushing, said seal means being generally annular in configuration and having an inner periphery in close abutting relationship with the cast ingot, the arrangement being such that the bellows will flex to follow any nonlinearity in the ingot as it is cast, and guide rolls beneath the seal means and between which the ingot passes, the guide rolls being spaced from the seal means a sufiicient distance to permit lateral movement to the ingot as it travels downwardly.

2. In continuous casting apparatus of the type in which a continuously cast ingot traveling in a vertically downward direction passes through a tank having a cooling liquid therein and thence through an opening in the bottom of the tank, the improvement in seal means around said opening in the bottom of the tank for preventing the excessive escape of liquid from the tank, comprising a guide bushing surrounding the ingot below the opening in the tank, said guide bushing having an inner diameter larger than the diameter of said ingot, an annular flexible bellows interconnecting the guide bushing and the tank to form a cavity communicating with said tank, said bellows permitting movement of the bushing at right angles to vertical movement of the ingot, an annular first seal around the bottom of said guide bushing in intimate contact with said ingot, an annular spacer secured to the bottom of said first seal and of diameter larger than the diameter of said ingot, a second annular seal around the bottom of said spacer and in intimate contact with said ingot, and means for introducing air under pressure into said annular space between the first and second seals, the air passing upwardly through said first seal to form bubbles which pass upwardly in the tank.

3. In continuous casting apparatus of the type in which a continuously cast ingot traveling in a vertically downward direction passes through a tank having a cooling liquid therein and thence through an opening in the bottom of the tank, the improvement in seal means around said opening in the bottom of the tank for preventing the excessive escape of liquid from the tank, comprising a guide bushing surrounding the ingot below the opening in the tank, said guide bushing having an inner diameter larger than the diameter of said ingot, an annular flexible bellows interconnecting the guide bushing and the tank to form a cavity communicating with said tank, said bellows permitting movement of the bushing at right angles to vertical movement of the ingot, said guide bushing having a flat lower surface, a flat annular first seal seated against the fiat lower surface of said guide bushing and having an inner diameter in intimate contact with said ingot, an annular spacer secured to said guide bushing and arranged to hold said first seal in snug abutting relationship with said lower surface of the guide bushing, said annular spacer having a diameter larger than the diameter of said ingot, a second annular flat seal secured to the bottom of said spacer and having an inner diameter in intimate contact with said ingot, said first and second seals being formed from resilient material, and means for introducing air under pressure into said annular space between the first and second seals.

References Cited UNITED STATES PATENTS 2,310,635 2/1943 Hopkins 164- 5 FOREIGN PATENTS 752,454 9/ 1952 Germany. 753,985 5/ 1951 Germany. 816,290 10/ 1951 Germany. 830,387 2/1952 Germany. 832,474 2/ 1952 Germany.

J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

Claims (1)

1. IN CONTINUOUS CASTING APPARATUS OF THE TYPE IN WHICH A CONTINUOUSLY CAST INGOT TRAVELING IN A VERTICALLY DOWNWARD DIRECTION PASSES THROUGH A TANK HAVING A COOLING LIQUID THEREIN AND THENCE THROUGH AN OPENING IN THE BOTTOM OF THE TANK, THE IMPROVEMENT IN MEANS FOR PREVENTING THE SUBSTANTIAL ESCAPE OF LIQUID THROUGH SAID OPENING IN THE TANK COMPRISING A GUIDE BUSHING SURROUNDING THE INGOT BELOW THE OPENING IN THE TANK, AN ANNULAR FLEXIBLE BELLOWS INTERCONNECTING THE GUIDE BUSHING AND THE TANK TO FORM A CAVITY COMMUNICATING WITH SAID TANK, SEAL MEANS CARRIED ON THE LOWER END OF SAID GUIDE BUSHING, SAID SEAL MEANS BEING GENERALLY ANNULAR IN CONFIGUARATION AND HAVING AN INNER PERIPHERY IN CLOSE ABUTTING RELATIONSHIP WITH THE CAST INGOT, THE ARRANGEMENT BEING SUCH THAT THE BELLOWS WILL FLEX TO FOLLOW ANY NONLINEARITY IN THE INGOT AS IT IS CAST, AND GUIDE ROLLS BENEATH THE SEAL MEANS AND BETWEEN WHICH THE INGOT PASSES, THE GUIDE ROLLS BEING SPACED

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