US3780789A

US3780789A - Apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys

Info

Publication number: US3780789A
Application number: US00277263A
Authority: US
Inventors: M Unger
Original assignee: Alusuisse Holdings AG
Current assignee: Alcan Holdings Switzerland AG
Priority date: 1969-10-08
Filing date: 1972-08-02
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25
Also published as: DE2049521C3; NO132858B; AT309711B; BE757226A; YU35311B; NL7014655A; CA925674A; IS1948A7; CH495798A; JPS5027030B1; FR2064214A1; DE2049521B2; NL156621B; GB1251469A; IS873B6; FR2064214B1; NO132858C; DE2049521A1; YU244970A; ZA706806B

Abstract

Apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising a distributing launder for the casting metal, a plurality of water-cooled continuous casting molds, a common lowering platform movably arranged in a pit and carrying the starting dummies of all the molds in a common fashion, the molds are disposed in a fluid-tight manner in a common cooling box, the distributing launder including openings which approximately match the cross section of the molds which are disposed below the level of the openings, a jacket surrounding each mold and forms with the exterior side of the associated molds a chamber for the cooling water and has apertures in its upper part for the inlet of the cooling water from the common cooling water box, the jacket also having further apertures in its lower part for the outlet of the cooling water from the chamber.

Description

United States Patent 1 .Unger [451' Dec. 25, 1973 [75] Inventor: Manfred Ungerg'Sierre, Switzerland [73] Assignee: Swiss Aluminium Ltd., Chippis,

Switzerland [22] Filed: Aug. 2', 1972 [21] Appl. No.: 277,263

Related US. Application Data [63] Continuation of Ser. No. 78,687, Oct. 7, 1970,

abandoned.

[30] Foreign Application Priority Data Oct. 8, 1969 Switzerland 15043/69 [52] US. Cl. 164/283 R, 164/89 898,801 7/1944 France 164/281 1,161,668 3/1958 France.... 164/281 1,354,818 2/1964 France.... 164/281 891,444 9/1953 Germany 164/281 93,660 l/l959 Norway 164/82 Primary ExaminerR. Spencer Annear Attorney-Ernest F. Marmorek [5 7 ABSTRACT Apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising a distributing launder for the casting metal, a plurality of water-cooled continuous casting molds, a common lowering platform movably arranged in a pit and carrying the starting dummies of all the molds in a common fashion, the molds are disposed in a fluid-tight manner in a common cooling box, the distributing launder including openings which approximately match the cross section of the molds which are disposed below the level of the openings, a jacket surrounding each mold and forms with the exterior side of the associated molds a chamber for the cooling water and has apertures in its upper part for the inlet of the cooling water from the common cooling water box, the jacket also having further apertures in its lower part for the outlet of the cooling water from the chamber.

2 Claims, 9 Drawing Figures PAIENTEBDEBZS i875 Fig. 3

Fig. 2

Fig. 5

Fig. 4

Fig. 7

Fig. 6

PATENTEH D5825 i975 SHEU3BF3 65 Fig. 8

APPARATUS FOR THE VERTICAL MULTIPLE CONTINUOUS CASTING F ALUMINUM AND ALUMINUM ALLOYS This is a continuation of application Ser. No. 78,687, filed Oct. 7, 1970 now abandoned.

FIELD OF THE INVENTION The present invention concerns an apparatus for the vertical multiple continuous casting of billets or slabs made from aluminium and aluminium alloys which overcomes the difficulties associated with hitherto known apparatus and permits billets or slabs of any simple cross section to be cast simultaneously, whereby the necessity of simultaneously setting and supervising several floaters or similar regulating devices is eliminated.

BACKGROUND OF THE INVENTION For many years now the simultaneous casting of billets as well as of rolling slabs made from aluminium and aluminium alloys has been carried out in vertical multiple continuous casting apparatus. This type of apparatus differs from the usual single mold casting apparatus inasmuch as several continuous casting molds are arranged parallel to each other and each with its own starting dummy. The cast billets or slabs are lowered simultaneously into a pit by means ofa common lowering platform. The molds used are the usual short molds for continuous casting; they are water cooled, whereby the cooling water emerging from them is sprayed against the billet as it leaves the mold. This type of mold is illustrated in pictures 398 and 401, page 401 of Handbuch des Stranggiessens" 1958, published by Aluminium Verlag Gmbl-l, Dusseldorf, West Germany. The molds mostly have a simple, preferably circular or square cross section, although they can also be of a more complicated shape, such as, hexagonal, or octagonal, or T or I shape. Apart from the common lowering platform and common distributing launder to which the molten metal is fed through a channel and from where it flows into the mold via a regulating device (usually consisting of a nozzle with a regulating float).

Multiple continuous casting apparatus for billets are described and illustrated in the journal Metall published by Metall-Verlag, GmbH, Berlin-Grunewald, West Germany, in Vol. (1961 No. 3 pages 205-206 (Multiple continuous casting apparatus by Michael F lynn, Mfg. Corp. in Philadelphia, USA); in Vol, 16 (1962), No. 4 page 294 (Apparatus used by Vereinigte Leichtmetall-Werke Gmbl-l in Germany), and in Vol. 22 (1968) No. 3 pages 229-230 (Apparatus used by Consolidated Aluminium Corporation, New

.lohnsonville (USA) and Vereinigte Aluminium-Werke AG, Lippewerk, Germany).

Multiple continuous casting apparatus of the types described are widespread since the increase of the number of billets or slabs which can be cast in one operation is a necessity both from the standpoint of the output as well as of economy.

The increase in the number of molds, particularly in respect to multiple continuous casting apparatus for billets has, of course, presented many problems. These chiefly concern the simultaneous supervision of several floaters, especially when casting commences. Furthermore, the problem of relubrication when longer billets or slabs are cast, has to be solved.

The level of the liquid metal in the distributor is known to be set as desired and is preferably automatically maintained, several methods are known in the prior art in this respect.

The feeding of the metal into the mold in the prior art devices is controlled in the usual manner, that is, by float valves. In a known apparatus the tubular molds made from graphite or silicon carbide are laid in their entire lengths on the bottom ofa furnace. US. Pat. No. 1,868,099, for example, describes that the outlets in the bottom of the furnace which is filled with a copper melt serve as molds for the simultaneous casting of several billets.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a novel multiple continuous casting apparatus which eliminates the drawbacks associated with known multiple casting apparatus.

The apparatus according to the invention, similarly to the known multiple continuous casting apparatus, has a number of short continuous casting molds, a common distributing launder and a common lowering platform which carries the starting dummies of all the molds and which is movable up and down in a common pit, and a cooling box which surrounds all of the casting molds and is arranged to be supplied with water.

The invention is characterized by the molds being in fluid-tight arrangement beside each other below apertures provided in the bottom of the distributing launder which approximately matches their cross sections and that every mold is encased in a jacket within the cooling box which together with the exterior wall of the mold forms a chamber for the cooling water, the top part of the chamber being provided with apertures for the inlet ofthe cooling water from the common cooling water box, while the lower part of the chamber being also provided with apertures (holes or slits) to permit the cooling water to emerge and, which are preferably shaped so that in operation, the cooling water is directed in the form of a jet toward the emerging billet or slab. The cooling water may as well be allowed to flow into the pit without being sprayed onto the billets.

The principal differences of the present invention from the usual vertical multiple continuous casting apparatus for aluminium and aluminium alloys will be made clear when comparing the characteristics of the apparatus according to the invention: the molds are not independent of the furnace, as with the known apparatus, but are directly connected with the bottom of the container (in this case the distributing launder and, therefore, when in operation, there is no level of liquid metal in their forming cavities, that is to say, no runner head. The casting conditions are, therefore, quite different from those with molds independent of the furnace. Moreover, the molds are not equipped with individual regulating devices; when in operation, the metal flows from the distributing launder directly into the molds without the use of nozzles and without the necessity of setting and supervising a float for each mold.

A very significant feature of the invention is the new fashion of conducting the cooling water into the common cooling box. Normally, in the apparatus according to the invention, only cross sections of uniform type are cast simultaneously. For this reason the upper apertures in the chambers around the molds are of equal dimension and arranged at equal height; therefore, when in operation, a uniform flow of water takes place in the annular. chambers of all the molds, and as a result, the molds are uniformly cooled. When equally sized and equally shaped molds care is of course taken that all apertures for the outlet of water from the chambers around the molds are also of the same shape and dimension and arranged at the same level so that the opposite sides of thecross sections of all billets are uniformly cooled.

The uniform flow of water into the chambers around the molds is not only secured by the apertures being of the same shape, dimension and at the same height, but

also by a constant water level in the common cooling water box which is maintained as soon as the operation is commenced. The molds of the apparatus according to the invention are appropriately secured in the common cooling water box on which the common distributing launder is fixed in a fluid-tight manner. This considerably facilitates the assemblying work and the replacing of molds by new, or newly prepared ones, or by molds of other dimensions. The level of the liquid metal in the distributing launder is set as desired and is preferably automatically maintained; this can be done by methods known in the prior art.

The feeding of the metal into the mold is not controlled in the usual manner of the known multiple continuous casting apparatus, that is, by float valves, but depends quantitatively entirely on the lowering speed of the lowering platform since no nozzles are provided to limit the flow of metal.

The apparatus according to the invention for the vertical multiple continuous casting of aluminium and aluminium alloys basically differs from the apparatus proposed by the afore-mentioned-U.S. Pat. No'. 1,868,099. The molds of this prior art are not short continuous casting molds and there is no common water box etc. Such known apparatus would be useless for the multiple continuous casting of billets and rolling slabs of acceptable quality made from aluminium and aluminium alloys..

' The multiple continuous casting apparatus according to the invention allows for various types of short, watercooled continuous casting molds to be fitted; the molds can be either of metal or of a type which is provided with a non-metallic lining.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readily apparent from the-following description of a preferred embodiment thereof shown, by way of example, in the accompanying drawings, in which:

FIG. 1 shows diagrammatically partly in vertical section a form of the apparatus according to the invention having four metallic continuous casting molds for billets, the starting dummies; the lowering platform and the upper part of the pit;

FIG. 2 a mold for billets of a smaller diameter than those in FIG. 1;

FIG. 3 a billet mold with graphite and Marinite inserts;

FIG. 4 a billet mold with its inner surface protected by a chrome or plastic coating;

FIG. 5 a billet mold with a graphite insert which'is partly thermally insulated;

FIG. 6 a billet mold with lubricating slit; FIG. 7 a graphite mold;

FIG. 8 shows diagrammatically and partly in section two slab molds with graphite and Marinite inserts in the casting apparatus;

FIG. 9 shows sections of two graphite molds for slabs, also in the casting apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, the apparatus basically comprises a distributing launder 10, four short continuous casting molds 11 for billets, a common cooling water box 12, for the molds 11, the starting dummies 13 of the molds 11, a lowering platform 14 and a pit 15.

The launder 10 comprises a frame 16 which is surrounded by a horizontal flange 17, both being made from a 5 mm thick steel sheet; a bottom 18 which also serves as the top of the cooling water box 12; and a 20 mm thick heat-resistant internal lining 19 which is made from a material such as Superplastic" or Marinite (both Registered Trade Marks). The flange 17 is firmly secured to the plate 18 by cap screws 29 and there is a layer of Fibrefrax paper between them. The launder 10 is square in plan form, the length of its sides at the'upper edge measuring 65 cm, and has four circular bores 41 in its metal bottom 18. Above these bores 41 in the lining 19 there are four circular apertures 20 whose diameter matches the internal diameter of the parts of the molds 11 which are set into the bores 41. In use,- the metal to be cast is fed into the launder 10 by means of a conventional feed channel 21 which is connected to the casting furnace (not shown) its outlet end resting on a support 22 in a recess 22a in the frame 16. The water cooling box 12 is made of aluminium plate and sheet which have been welded together. Its shape matches the square form of the launder and is composed of a 20 mm thick bottom plate 24, the 20 mm thick top plate 18 and four 10 mm thick side walls 25. An aperture 27 is provided in each of the sides of the water box 12 for hose connections to permit the inlet of water to the box 12. The molds 11, which are made from heat hardened ALMgSi, extend vertically through the water box 12, their upper ends fitting into the bores 41 in the plate 18, circular collars 30 on the molds engaging in corresponding rebates in the plate 18 to correctly position the molds, and their lower ends 23 fitting into corresponding apertures in the bottom plate 24. Rubber rings 32 and 33 form water-tight seals between the molds 11 and the top and

bottom plates

18 and 24 respectively. Surrounding each mold 11 within the box 12 is a cylindrical jacket 26 formed from 5 mm thick metal plate and welded to both the top and

bottom plates

18 and 24. Each jacket forms an annular chamber 31 surrounding the mold and separated from the remaining common hollow space within the box 12 apart from small communicating openings formed by slots 34 at intervals in the upper edge of the jacket 26. These openings, in use, allow water into the chambers 31 in order to cool indirectly the billets being formed by the molds 11. The lower ends 23 of the molds l 1 are each offset in a radially outward direction, and similarly to conventional molds, each offset portion contains a great number of small holes 35 which are directed obliquely to the mold axis whereby, during operation, the cooling water which has already served as an indirect'cooling agent to the billet, is sprayed from the chamber 3-1 against the billet as it emerges from the mold and directly cools it further. The retention of the molds 11 in position is effected by the aid of cap screws 36 which are fitted into the bottom plate 24 and with short flat bars 37. i

The starting dummies 13 are shown in the starting position. They rest on the lowering platform 14 which, after casting on is lowered into the pit 15 at a predetermined speed. Before casting commences, the pit is filled with water up to, for example, the dashed line 38, shown in FIG. 1.

The billet molds 11 shown in FIG. 1 are each provided with a graphite lining 39, which forms the interior wall of the mold, and determines the diameter of the billet to be cast. In order to maintain the desired height of the cooling surface, a thermally insulating ring 40 made from Marinite" is placed on top of the lining 39. The solidification of the molten metal which is cast into the mold only begins below the lower rim of the Marinite" ring 40, the upper rim fitting snuggly with the lower surface of the lining l9 and the diameter of the ring 40 at this point matching that of the aperture in the lining 19 on the bottom 18 of the launder 10.

In operation, the apertures 20 remain free to allow the metal melt in the launder to flow into the molds. There are no floaters or nozzles to interfere with the flow as in the conventional multiple continuous casting apparatus, and the flow of the melt is steady with no transmission capacity of nozzles to be taken into consideration when setting the lowering speed of the platform 14. In contrast to the usual multiple continuous casting apparatus, no runner head is present in the mold after starting of casting and therefore there'is no risk of oxides from the metal surface being drawn into the casting.

Various different types of short continuous casting molds may be used in the apparatus according to the invention, the essential-feature of which is the combination of a common launder with the short continhous casting molds secured-to its bottom (eliminating the use of float valves on the inlet of the molds), and with a common cooling water box which contains a number of circular jackets each surrounding a mold and constructed to form a dam whereby the entry of water from the cooling box into the chamber formed round the mold by the jacket is controlled for the indirect cooling of the billet formed by'the mold. Another important point is the thermal insulation of the upper part of the mold, which is effected either by the inserted ring 40 made from thermally insulating material, as in FIG. 1, or by an insulating layer on the exterior of the mold. The height of the cooled zone of the mold wall has to be adjusted for every casting programme.

This height is one of the most important casting factors, others being the temperature of the water, the flow speed, and the temperature and level of the metal in the launder.

The molds 11 of the apparatus in accordance with the invention can be replaced easily. To avoid damage to the lining 19, they are drawn from below the water box 12 after first loosening the cap screws 36 and the flat retaining bars 37.

Example: When casting pure aluminium 99.5 in the apparatus shown in FIG. 1, a lowering speed of 15 cm/min. is maintained; the metal melt in the launder has a temperature of 690 to 700C; and the quantity of cooling water used per mold is approximately. 100 litres per min. In the case of the example of FIG. 1 the graphite liners 39 have an inner diameter of 200 mm and a wall thickness of 7 mm. The wall thickness of the ameter of thebores 41 in thewater box is of corresponding size, so thata tight fitting is achieved when the molds 11 are inserted.

Molds for billets of a smallerdiameter, for example 180 or 150 mm, can be inserted in the water box of the same apparatus, but they have to be suitably constructed so that they fit into the bores 41 in the top plate 18. a

FIG. 2 shows a mold construction 42 which would be satisfactory. The mold is provided in its upper part with an outwardly directed flange 43 whose outer diameter (without taking the collar 44 into account) corresponds to the diameter of the bore 41 When moldsof a smaller diameter are inserted, the lining 19 of the metal base 18 of the launder has to be adjusted to match the smaller diameter, and the offsetting 45 at the lower end of the mold has to be increased to match the aperture in the bottom plate 24. g

The inserted ring 46, made of fireproof material, for example Marinite," has its outer circumference mating snuggly with the aperture in the lining 19 as well as with the upper end of the inner wall of the mold 42.

FIG. 3 shows a billet mold 47 which is constructed in such a way that the metal melt remains in itsyliquid state almost as far as the outlet of the mold. This mold is,

composed of concentrically arranged rings; an inner ring 48 made from graphite, and outer ring 49 made from aluminium or steel, and a spacing ring 50 made from an insulating material. 51 are the bores through which the cooling water is sprayed towardtheemerging billet.

FIG. 4 shows a billet mold 52 made from aluminium with a Marinite" insert 53 at its upper end. The mold is similar to that shown in FIG. 1 except that the graphite liner39 in FIG. I is replaced by an integral part of the mold wall.

FIG. 5 shows a billet mold 54 made from an aluminium alloy withan insert 55 made fromgraphite and a layer of thermal insulation, for example asbestos or The billet mold 57 shown in FIG. 6 is made substantially of aluminium and has a circular slit 58 through which a lubricating oil is pressed against the forming billet. The reference numeral 59 indicates the lubricating oil channels in the mold wall and 60 indicates the lubricating oil feed hole, while 61 is a Marinite" ring.

In FIG. 7 the billet mold 62 consists entirely of graphite.

FIG. 8 is a perspective view of a casting apparatus withtwo ingot molds 63 which are, in principle, constructed in the same way as'the billet molds 11 shown in FIG. 1. The apertures 64 and the bores 65 have a rectangular instead of a circular form. The starting dummies are not shown, for simplicitys sake, and neither are the lowering platform 14 and the pit 15.

In the apparatus shown in FIG. 9 the ingot molds 66 are formed entirely of graphite; otherwise the apparatus is the same as that of FIG. 8. In the case of slab molds the bores for the outflow of the cooling water from the molds towards the forming ingot (not shown) are, as a rule, not at equal intervals around the periphery of the mold as in the case of billet molds and they haveinot the'same diameter, since the usually differing cooling conditions on the wide and on the narrow sides have to be taken into account. Such features are known in conventional apparatus.

From the above, it is apparent that although the invention has been described hereinbefore with respect to a certain specific embodiment thereof, it is evident that many modifications and changes may be made without departing from the spirit of the invention. Accordingly, by the appended claims, we intend to cover all such modifications and changes as fall within the true spirit and scope of this invention.

I claim:

1. Apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising a common refractory lined distributing launder for the casting metal,

a plurality of water-cooled short continuous-casting mold,

a common lowering platform movably arranged in a pit, said lowering platform carrying the stopping dummies of all said molds,

a common cooling box, said mold being disposed in fluid-tight manner in said common cooling box, said distributing launder including openings which approximately match the cross section of the mold, said mold being disposed below said openings,

thermal insulation means insulating the upper part of the molds and making contact with the refractory material of the distributing launder,

a jacket surrounding each mold, each jacket together with the exterior side of the associated mold forming a chamber for the cooling water, said jacket having apertures in its upper part for the inlet of the cooling water from said common cooling water box into said chamber, said jacket having further apertures in its lower part for the outlet of the cooling water from said chamber.

2. An apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising in combination a common refractory lined distributor of a casting metal and having a base defining a plurality of apertures, one for each casting,

a corresponding plurality of short continuous casting molds connected to said base throughout their entire cross-sectional area thereby restricting the entire apparatus to have but a single metal lever within the distributor and above all the molds so that the molten metal mass is continuous from the lever in the distributor downwards into the mold filling the mold entirely,

thermal insulation means insulating the upper part of the mold and making contact with the refractory material of the distributor,

a starting dummy disposed in each mold,

a platform movably arranged below all of said molds for lifting and lowering said dummy,

a cooling box surrounding all of said molds and being operable to be supplied with a cooling fluid,

a plurality of jackets disposed within said cooling box and each surrounding the wall ofa mold and defining with the mold wall a cooling chamber, the outer portion of each cooling chamber having near the top openings to provide for a substantially uniform flow of the cooling fluid from said cooling box to said chamber and including radially off-set lower ends having outlets near the bottom close to the molds so that, in use, the cooling fluid will flow from the cooling box into the chambers to cool indirectly the castings formed in the mold and will exit and be directed by said outlets from the chambers towards the casting emerging from the mold,

thereby directly cooling the discharged casting.

Claims

1. Apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising a common refractory lined distributing launder for the casting metal, a plurality of water-cooled short continuous casting mold, a common lowering platform movably arranged in a pit, said lowering platform carrying the stopping dummies of all said molds, a common cooling box, said mold being disposed in fluid-tight manner in said common cooling box, said distributing launder including openings which approximately match the cross section of the mold, said mold being disposed below said openings, thermal insulation means insulating the upper part of the molds and making contact with the refractory material of the distributing launder, a jacket surrounding each mold, each jacket together with the exterior side of the associated mold forming a chamber for the cooling water, said jacket having apertures in its upper part for the inlet of the cooling water from said common cooling water box into said chamber, said jacket having further apertures in its lower part for the outlet of the cooling water from said chamber.

2. An apparatus for the vertical multiple continuous casting of aluminum and aluminum alloys comprising in combination a common refractory lined distributor of a casting metal and having a base defining a plurality of apertures, one for each casting, a corresponding plurality of short continuous castIng molds connected to said base throughout their entire cross-sectional area thereby restricting the entire apparatus to have but a single metal lever within the distributor and above all the molds so that the molten metal mass is continuous from the lever in the distributor downwards into the mold filling the mold entirely, thermal insulation means insulating the upper part of the mold and making contact with the refractory material of the distributor, a starting dummy disposed in each mold, a platform movably arranged below all of said molds for lifting and lowering said dummy, a cooling box surrounding all of said molds and being operable to be supplied with a cooling fluid, a plurality of jackets disposed within said cooling box and each surrounding the wall of a mold and defining with the mold wall a cooling chamber, the outer portion of each cooling chamber having near the top openings to provide for a substantially uniform flow of the cooling fluid from said cooling box to said chamber and including radially off-set lower ends having outlets near the bottom close to the molds so that, in use, the cooling fluid will flow from the cooling box into the chambers to cool indirectly the castings formed in the mold and will exit and be directed by said outlets from the chambers towards the casting emerging from the mold, thereby directly cooling the discharged casting.