US2708297A - Continuous casting apparatus - Google Patents

Description

May 17, 1955 P. P. zElGLER CONTINUOUS CASTING APPARATUS Original Filed Sept. 3, 1953 4 Sheets-Sheet 1 I G l.

INVENTOR. PAUL P. ZEIGLER BY 5 f ATTORNEY May 17, 1955 P. P. zElGLER 2,708,297 v coNTINUoUs'cAsTING APPARATUS f Original Filed Sept. 3, 1'5353V 4 Sheets-Sheet 2 l l J l BTTORNE May 17, 1955 P. P. zElGLER CONTINUOUS CASTING APPARATUS Original Filed Sept.- 3, 1953 4 Sheets-Sheet 3 FIG. :a

' INVENTOR.

PA u; P. zal @MSR :ATTORNEY May 17, 1955 P. P. zElGLER 2,708,297

CONTINUOUS CASTING APPARATUS Original Filed Sept. 3, 1953 4 Sheets-Sheet 4 INVENTOR. PMU. P ZIGLSR ATTORNEY arent @tice Patented lilla? l?, 1955 CGNTINUGUS CASTNG APPARATUS Paul P. Zeigler, Spokane, Wash., assigner to Kaiser Aluminum & Chemical Corporation, aldaud, Calif., a corporation of Eelaware Original application September 3, 1953, Serial No. 378,365. Divided and this application (letober 12, i954, Serial No. 461,779

5 Claims. (Cl. .Z2-57.2)

rl`his invention relates to the casting of metals. It mo e particularly relates to an apparatus for controlling the cooling of continuously cast ingots.

This application is a division of my copending application Serial Number 378,365, filed September 3, 1953.

in the continuous casting of various metals, including aluminum and aluminum alloys, molten metal is fed L to one end of an open-ended mold shell and is partially cooled therein to form an outer shell of soliditied metal. The casting is continuousy withdrawn by any suitable means from the opposite end while at the same time a supply ot coolant, usually water, is applied continuously to the casting as it emerges from the mold. The term continuous casting referred to herein is intended to include casting procedures which may be of a strictly continuous nature (in which the casting is cut to length without interruption of the casting procedure) or where the casting is oi a semi-continuous nature; i. e., a casting of desired length may be cast, the ow of metal stopped, the casting removed and the procedure commenced anew. ln the casting of aluminum and aluminum alloys, one method commonly used is that disclosed in the Ennor Patent No. 2,30l,027.

in the Ennor patent the cooling is accomplished by means of a water spray directed around the periphery of the mold shell by means of spray pipes or a spray box. VJater iets impinge upon the outer surface of the mold and the embryo ingot as it emerges below the mold. The amount ot water applied or the amount ot cooling accomplished is uniform about the periphery of the mold and casting.

in all of these prior cooling methods the water which is applied to the casting is allowed to run down the full length of the surfaces of the ingot below the mold. While the application of coolant directly to the embryo ingot immediately upon emergence from the mold shell has served to promote rapid freezinsT and to improve metallurgical quality considerably, it has been found in the casting of certain high strength aluminum alloy ingots that the uninterrupted flow of coolant down the ingot surfaces leads to excessive internal stresses resulting in the occurrence of defects such as center cracks which render the ingots unsuitable for working or machining and thus result in considerable economic loss to the inustry. These defects are caused by excessive cooling of the lower sections of the ingot or billet giving rise to undesirably high temperature gradients bett 'een the inner and outer portions of the ingot or billet. That is to say, if the large volume of cooling water required for rapid cooling of the embryo ingot ,inst below the mold is allowed to run down too great a distance below the bottom of the mold excessive heat abstraction takes place and the aforementioned defects will develop. This distance will vary with the type of alloy and with the size of the ingot or 'c-illet being cast, as w ll as other factors involved in any contention-al casting operation.

AThe excessive cooling of the ingot can be eiectively revented by means of this invention. wherein there is a lill controlling of the coolant owing down over the lower portion of the ingot and a restriction of its length of travel down the surfaces or the ingot by the use of a gas jet wiper located at the proper distances from the bottom of the mold which removes the coolant from the surface of the ingot. The distance of the gas wiper from the bottom of the mold shell where the coolant is removed from the ingot surface is determined by factors such as chemical composition or" the ingot, size and shape ot" inve-t, rate of ingOt withdrawal from the mold shell, etc.

Although the device of the instant invention has been tt and particularly adapted for use in the continuous casting of aluminum alloys, its use is not restricted thereto and it can be successfully employed in any casting rocess Jfor other metals where the danger of center cracking other serious defects caused by excessive cooling ot' the ingot or billet exists.

Accordingly, it is an object of this invention to provide a novel means for preventing excessive cooling of ingots, bi ts and the during continuous casting thereof,

A more specific object of this invention is to provide a gas Jiet device for removal of coolant flowing down the surface of ingots, billets, and the like during the coz nous casting thereof in order to prevent excessive cooling thereof.

Iurther objects advantages of the invention will be apparent from the following detailed description taken in conjunction 'with the drawings which illustrate the invention as applied to the casting of rectangular or sheet ragots, wherein:

Figure l is a broken plan View showing the general arrangement of a continuous casting mold for sheet ingots the wipers used therewith;

Figure 2 is a vertical, sectional view taken along line 2 2 of Figure the position assu.. ed by the ingot as it is lov/ere from the mold being shown in dotted lines;

Figure 3 is broken pian view of a modification of the apparatus of Figures l and 2 shows the general arrangement of a continuous casting mold for sheet ingots and a moditied arrangement for the gas wipers shown Figures 1 and 2, and

Figure 4 is a vertical, sectional View taken along line Ll-for Figure 3, the position assumed by the ingot as is lowered from the mold being shown in dotted lines.

'With further reference to the drawings and particularly t igure 2, there is shown a mold shell 2 suitably mounted over a casting pit 3 by any of the conventional means. Wlhin ti e mold s yill 2 and extending therebelow is an enforvY ingot l2 comprising a pool of molten metal 5 s 'ditied casting En, the pool 5 extending downwardly forming a liquid crater or core within the ingot.

commonly used. The solidified porthe incot rests upon a block i7 which block in rn is up n a vertically adjustable platen 1S. Suitable means are provided for cooling the mold shell 2 and also for directly cooling the embryo iugot 12 as it emerges from the shell. These means may consist of the spray boxes 4 containing the cooling water. These boxes encircle the ingot. From these spray boxes water is directed affainst the outer surfaces of the mold shell 2v and the surfaces of the ern ryo ingot emerging therefrom. Ailied to each of these spray boxes is a header tank (not shown) connected to the spray box by suitable means for regulating the amount of water head in the boxes.

Located at predetermined distances below the bottom of the mold shell 2 is a plurality of gas jet nozzles 33, which project from segments of the gas header pipe 9.

F The gas header pipe 9 is comprised of a lower U-shaped portion, to each leg of which there is connected by suitable means and in gas flow relation therewith a plurality Y faces of the ingot.

of pipe segments of substantially the same length as and mounted parallel with each lower leg. It is to these segments 10 that nozzles 13 are connected. These nozzles are mounted in battery formation and several tiers of nozzles are provided at each face of the ingot. The nozzles are mounted in such a manner as to direct gas streams 23 against the surfaces of the ingot emerging from the mold shell and to remove the water owing down the ingot surfaces. These nozzles can be made active or inactive, as required.

In the casting of rectangular or sheet'ingots, wherein the thickness is small relative to the length and width there is also a tendency to produce defects known as corner and/or edge vcracking due to a greater rate of heat abstraction at the corners and/or edge than at the faces. The term edges, as used herein, is defined as the relatively narrow longitudinally extending surfaces of the ingot as distinguished from the relatively wide ingot faces. The term corner, as used herein, is defined as the point or place which joins an ingot edge to an ingot face. The differential in the rate of heat abstraction may becornpensated for by proper selection of active nozzles in the various tiers above described. rl`he end nozzles of the first and/or second tier are made active, thereby allowing the coolant to flow down the ingot faces until it is removed by the active nozzles spaced from the ends of the second and/or third or last tier, as the case may be. It will thus be seen that by proper selection of active nozzles the line of coolant removal for the corners and edges of the ingot occurs at a level or distance closer to the mold shell than the line of coolant removal for the By removing the coolant from the corners and edges of the ingot, which are normally subject ot a greater rate of heat abstraction, at a level closer to the mold shell than the level of removal of coolant from the ingot faces, the seriousdefects of corner and/or edge cracking, as well as center cracking, are eliminated or substantially eliminated. Although Figure 2 shows three tiers of nozzles on each side of the ingot, it is to be understood that two tiers can be used satisfactorily. The provision of more than two tiers of nozzles is desirable, however, in that it permits greater adjustability of the levels Vof coolant removal for the faces, edges and corners of the ingot. Y

The gas wipers are generally positioned such that the gas streams are directed toward the ingot surfaces at an angle of from about to 50 with respect to a hori zontal lplane normal'to the ingot face. The wipers are spaced back from the ingot surface to allow ample clearance between the nozzles and the ingot surface. In most instances a spacing of from about to 11/2 inches has been found to give a satisfactory deflection clearance about the nozzles, thereby avoiding the dropping of water back into the nozzles which would interfere with the otherwise smooth action of the wiper. The gas pressure is maintained at a ligure suitable for producing substantially clean lines of coolant removal. To avoid the effect of line pressure variations, a pressure regulator may be used on the inlet side of a control valve (not shown) so that the outlet pressure will remain constant for a given predetermined setting of the valve.

The term gas jet, as employed herein is intended to apply to any gas, including nitrogen, the noble gases as well as any other gaseous media. Obviously, air is the most economic gas for such use and is not hazardous in the continuous casting of aluminum and the majority of other metals.

Although other means maybe used for ensuring complete removal of the water initially removed by the nozzles, it is contemplated that there be associated with each battery of nozzles a horizontally mounted deector bafe V6. These baflles are successively bent along their lengths so as to form an inclined drain surface 7,'a curved portion 8 fitting about the upper outer periphery of the aforementioned pipe segments 10 of gas header pipe 9,

from the faces of the ingotis deflected against the baffles 6, whence it finally ows down over the drain surface 7 thereof, and into a suitable drain (not shown).

The gas header pipe 9 is connected to a suitable source of compressed gas supply such as by means of pipe 19. Associated with this pipe but not shownis a gas pressure gauge and a control valve provided with a setting indicator for regulating the pressure of the gas being emitted from the nozzles 13.

Each end of the gas header pipe 9 may be mounted upon a bracket 20 and L-shaped arms 21 may be connected directly to the gas header pipe 9 as indicated` in Figures l and 2 or tothis bracket. These arms are threadedly mounted upon shafts 22 suitably mounted on the frame 24, said frame also serving to mount the mold i shell 2. When shafts 22 are turned by the cranks 22a they will thereby cause brackets 20 and gas header pipe 9 to move upwardly or downwardly so that gas header pipe 9 and jet nozzles 13 may be drawn up or down with respect to the mold shell 2 and be placed at a greater or smaller distance from the mold shell, which distance will in turn be governed by such factors as the chemical cornposition of the alloy being cast, the size of the ingot or billet being cast, rate of withdrawal of the casting from the mold shell as well as other factors involved in any continuous casting operation. Also, by this means this distance can be adjusted during casting if necessary.

The nozzles 13 are of a design which will deliver a uniform stream of gas and can be of a standard type. These are preferably mounted closely together as shown in Figure l to give satisfactory coverage for the ingotY surfaces.

In Figure 2 there is also shown a longitudinal, curved metal guard 30 on one of the bafe anges which may be welded to each bafe flange 11 to protect the nozzles 13 during the removal of the ingot and to prevent molten metal splash from the ingot from clogging them.

la the operation of the instant device it has been found desirable to flange the baffles 6 downwardly above the gas nozzles to form a sharp or almost normal junction between gas stream 23 and baille flange 11 to avoid the creation of a partial vacuum at the point of alignment of the nozzles and baies, which would tend to pull the deected water 2S back into the gas stream 2.3. On the other hand, the proper curvature of the right angle bends 29 on the top or base of the flanges 11 causes a desirable partial vacuum at a proper point at the bend 29 which is in the deected stream of combined gas and Water which passes over it during operation. The partial vacuum pulls the deflected stream downward and over the drain baffle and helps prevent bounce and interference with the smooth water flow on the ingot above the point of water removal.

Although the v general arrangement of appartus described hereinabove in conjunction with Figures l and 2 is satisfactory in applying the invention to the casting of sheet ingots, it hasbeeu found preferable to utilize the modified arrangement as shown in Figures 3 and 4 where- Ain a single tier of nozzles is provided around the entire periphery of the ingot and wherein the nozzles along the edge and corner surfaces of the ingot are positioned at a level closer to the mold shell than in the case of the nozzles along the ingot faces. The structure in Figures 3 and 4 is substantially the same as that disclosed in Figores l and 2, with the exceptiton that the number of tiers or" nozzles along the ingot faces has been reduced to one and a battery or" nozzles has been added at each ingot edge, and the reference numerals indicate like parts inY 5 connected to a suitable source of compressed gas supply such as by means of pipe 33. As in the case of pipe 19, pipe 33 has associated therewith a gas pressure gauge and a control valve provided with a setting indicator for regulating the pressure of the gas being emitted from the nozzles 3f..

Pipe member 32 is preferably adjustably mounted on bracket 26. Projecting upwardly from bracket 2G are rod members 34. Pipe member 32 is provided with block members 35. Each block 3S has a vertical aperture 36 therein in alignment with a rod 34 adapted to receive the rod in sliding engagement. Blocks 35 are also provided with a threaded horizontal aperture opening into the vertical aperture. Within the horizontal aperture is provided a set screw 37 for rigidly securing pipe member 32 to rods 34. it will be seen that by this means set screws 37 may be loosened, pipe member 32 and mounted nozzles 31 moved vertically upward or downward to adjust the position thereof, as desired, relative to nozzles 13 and xed in this position by tightening set screws 37 upon guide rods 34. lt will be understood that nozzles 31 could suitably be mounted independently of bracket 2t).

Associated with nozzles 31 for ensuring complete removal of water initially removed by the nozzles from the edges and/or corners of the ingot is a horizontally mounted deflector baille 33 which is of substantially the same configuration as bathe 6. Batlle 38 is provided with suitable cut-out portions about blocks 35 and pipes 19 and 33.

It is to be understood with respect to the nozzle arrangements shown in Figures l to 4 that, if desired, provision can be made for regulating the gas under pressure emitted from each active nozzle so that the amount of coolant removed from the ingot by any one nozzle "l would be controlled.

It will thus be seen that by the instant invention there is provided a simple and yet effective apparatus for removal of coolant owing down the surface of the ingots, billets and the like during the continuous casting thereof in order to prevent excessive cooling of the casting. While the invention has been specifically' illustrated with reference to the casting of rectangular or sheet type castings, it will be apparent that the present invention has application to the removal of coolant from castings of various cross-sectional configurations, e. g., round, square, etc., and removal of the coolant may be at one or more levels.

it will be obvious that various modications and alterations may be made in this invention without departing metal ingots comprising a short mold shell, a spray box encircling said shell and adapted to spray a liquid coolant upon said shell and an embryo ingot emerging therefrom, the combination therewith of a plurality of air jet nozzles mounted close together and directed to discharge air against the ingot and towards the spray box, means for supporting said nozzles below said mold shell and spray box, and a baffle mounted on said nozzles and extending close to the embryo ingot emerging from said mold shell to deflect away from said ingot coolant removed front the ingot by air issuing from said nozzles.

2. ln an apparatus for the continuous casting of sound metal ingots comprising a mold shell, a spray box encircling said shell and adapted to spray a liquid coolant upon said shell and an embryo ingot emerging therefrom, the combination therewith of a plurality of gas jet means mounted close together and directed to discharge gas against the ingot and towards the spray box, bale means extending close to the embryo ingot emerging from said mold shell, said baie means being fixed relative to said jet means, means for supporting said jet means and said baie means below said mold shell and spray box, said means including means for adjusting the distance between the ,iet means and the mold shell, said baille means adapted to deflect away from said ingot coolant removed from the ingot by gas issuing from said jet means.

3. in an apparatus for the continuous casting of metal ingots without defects resulting from excessive cooling 4 comprising a short mold shell, a spray box encircling said shell and adapted to spray a liquid coolant upon said shell and an embryo ingot emerging therefrom, the combination therewith of a plurality of air jet nozzles mounted close together and directed to discharge air against the ingot and towards the spray box, means for supporting said nozzles below said mold shell and spray box, said means including tleans for adjusting the vertical distance between the nozzles and the mold shell, and a baille mounted on said nozzles and extending close to the embryo ingot emerging from said mold shell to deflect away trom said ingot coolant removed from the ingot by air issuing from said nozzles.

4. An apparatus according to claim 3 wherein said nozzles are positioned to discharge air upwardly against the ingot at an angle of from about 20 to 50 with respect to a horizontal plane normal to the ingot.

5. An apparatus according to claim 3 wherein said air Jiet nozzles comprise at least one row or nozzles.

References Cited in the tile of this patent UNITED STATES PATENTS 1,85,G99 Eldred July 19, 1932 2,079, i4 Williams May 11, 1937 2,246,903 Webster June 24, 1941 2,301,027 Ennor NOV. 3, 1942 2,414,269 Nicholls Jan. 14, 1947 2,424,640 Spooner July 29, 1947 2,515,284 Zeigler et al July 1S, 1950 2,651,82l Chadwick et al. Sept. 15, 1953 FOREIGN PATENTS 884,691 France May 3, 1943 258,517 Switzerland Nov. 30, 1943

Claims (1)

1. IN AN APPARATUS FOR THE CONTINUOUS CASTING OF SOUND METAL INGOTS COMPRISING A SHORT MOLD SHELL, A SPRAY BOX ENCIRCLING SAID SHELL AND ADAPTED TO SPRAY A LIQUID COOLANT UPON SAID SHELL AND AN EMBRYO INGOT EMERGING THEREFROM, THE COMBINATION THEREWITH OF A PLURALITY OF AIR JET NOZZLES MOUNTED CLOSE TOGETHER AND DIRECTED TO DISCHARGE AIR AGAINST THE INGOT AND TOWARDS THE SPRAY BOX, MEANS FOR SUPPORTING SAID NOZZLES BELOW SAID MOLD SHELL AND SPRAY BOX, AND A BAFFLE MOUNTED ON SAID NOZZLES AND EXTENDING CLOSE TO THE EMBRYO INGOT EMERGING FROM SAID MOLD SHELL TO DEFLECT AWAY FROM SAID INGOT COOLANT REMOVED FROM THE INGOT BY AIR ISSUING FROM SAID NOZZLES.

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