US2781562A - Apparatus for the continuous casting of metals - Google Patents

Description

Feb. 19, 1957 APPARATUS FOR THE CONTINUOUS CASTING OF METALS J. F. HOBBS ET AL Filed April 24, 1953 3 2 lg l B ((m W I a \4' l, FIG.I.

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- P a *2 1 Y 71008 #0558 az'TaMuzr United States Patent -APPARATUS FOR THE CONTINUOUS CASTING OF METALS John F..Hobbs and Nenfn'nun, Birmingham, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Application April 24, 1953, Serial No. 350,802

Claims priority, application Great Britain May 14, 1952 4 Claims. (Cl. 2257.2)

This invention relates to an apparatus for the continuous casting of metals and alloys, and more particularly to an improved mould for the continuous casting of rectangular slabs of aluminium and aluminium base alloys and other non-ferrous metals and alloys.

In the process for the continuous casting of rectangular rolling slabs of non-ferrous metals and alloys (the term continuous casting as used hereinafter includes both strictly continuous and semi-continuous processes, and the term slab as used hereinafter denotes a substantially rectangular section having a width (side) considerably exceeding its thickness end)) in most common use at the present time employing a water-cooled mould having a relatively thick and consequently rigid wall, a gap is formed between mould wall and ingot at a short distance below the molten metal surface due to contraction of the solidifying casting away from the mould. The consequent reduction in heat transfer in the. lower parts of the mould has three effects:

(a) It reduces the overall cooling efliciency of the process;

(b) In the case of, for example, certain aluminium base alloys it allows excessive surface exudation or blebbing to occur;

(c) In the case of, for example, certain aluminium base alloys an inferior metallurgical structure is obtained in the surface layers of the ingot such that surface milling to a depth of up to about half an inch is necessary to ensure satisfactory behaviour during subsequent rolling operations.

The object of the present invention is to reduce or to avoid completely the formation of this solidification gap between mould and ingot in simple and effective manner.

The invention comprises apparatus comprising a mould having end walls of normal rigid construction and side walls formed of thin sheet metal or other material of adequate thermal conductivity and adapted to be deflected inwardly to make substantially complete contact with the surface of the solidifying casting during at least the major part of its passage through the mould.

Deflection of the side walls may be effected by pressure exerted by the mould coolant, for example in the form of jets or sprays, and/or by means of applied air pressure. Air pressure may be used when the coolant exerts no considerable pressure on thewall of the mould, or it may be used to supplement the effect produced by coolant jets. Generally the air pressure required to eflect the necessary deflection will be only of the order of a few inches of water gauge. The air pressure may be applied by means of a suitably disposed series of jets, slits or the like in communication with a compressed air supply.

The thin flexible walls may be attached to the remainder of the mould at the top and sides or they may be allowed to float at one of these positions, being held in position by the applied coolant and/ or air pressure. When the flexible walls are not attached at their sides to the end walls, they should preferably overlap the end walls to an extent suflicient to avoid formation of a gap between the edge of the end wall and the flexible wall on deflection of the latter.

When the mould incorporates a coolant jacket to permit circulation of the coolant around the mould walls, the flexible side wallsare preferably attached to the remainder of the mould at the top and sides. At their bottom edge they may be connected to the lower flange of the coolant jacket by a flexible seal adapted to prevent loss of coolant but permit inward deflection of the walls, or the bottom edge may be free so that on deflection a slit is formed through which coolant flows from the jacket to cool the casting by direct contact.

It may be desirable to reduce the applied pressure at the commencement of a casting run in order to avoid too great a deflection of the mould walls until a solid shell of metal has formed in the mould.

' The rigid end walls of the mould are cooled in conventional manner and additional cooling by direct impingment of coolant jets on the cast ingot below the mould can be arranged in normal manner if desired.

By way of example brass sheet of 0.0035 in. thickness may be employed satisfactorily for the side walls of a water-cooled mould for easing aluminium base alloy slabs.

Two embodiments of the invention are illustrated diagrammatically in the accompanying drawing in which:

Figure 1 is a top plan view of a jacketed mould in accordance with the invention;

Figure 2 is a section on the line AA of Figure 1; but showing a casting in position;

Figure 3 is a section on the line BB of Figure 1;

Figure 4 is a top plan view of a non-jacketed mould in accordance with the invention;

Figure 5 is a section on the line CC of Figure 4; but showing a casting in position and in addition the cooling means for the side walls of the mould.

Figure 6 is a section on the line DD of Figure 4, but showing in addition cooling means for the end walls of the mould.

Referring to Figures 1, 2 and 3 of the drawing, the mould assembly 1 consists of a pair of curved rigid end walls 2 and a pair of flexible thin sheet metal side walls 3, the whole being fitted with a channel section water jacket 4 (coolant entry and exit pipes not shown) the upper portion of which constitutes a rectangular frame.

The jacket is rigidly connected to the end walls 2 and to the upper edge of the side walls 3, whilst the lower edge of the latter is connected to the lower flange of the jacket by flexible sealing means 5 which prevents loss of coolant from the jacket but permits inward deflection of the side wall to enable it to conform under the coolant pressure to the shape of the solidifying ingot. A unitary jacket may be employed for the whole mould, or the jacket may be divided into separate compartments for cooling side and end walls respectively, thus permitting ditferential rates of cooling if desired.

Referring to Figures 4, S and 6 of the drawing, the mould assembly 6 consists of a continuous flange 7 with rigid end walls 8 and flexible thin sheet metal side walls 9, the latter secured along their upper edge to the flange but not otherwise attached. The end walls are cooled by normal spray rings 10, whilst the side walls are cooled by banks of water jets 11 impinging over the full area of the walls.

We claim:

1. A continuous casting mold comprising a substantially rectangular frame, rigid end walls fixed to said frame and depending therefrom, side walls of thin, deformable, heat-conducting material fixed to said frame at their upper edges only and means for applying a coolant to the surfaces of said side walls away from the casting to 3 deflect the opposite surfaces against the casting as the casting shrinks during its travel through the mold.

2. The structure defined in claim 1 wherein said coolant applying means comprises spray heads projecting coolant against the surfaces of said side walls away from the casting.

3. The structure defined in claim 1 wherein said coolant applying means comprises a coolant containing jacket dependent from said frame, said side and end walls forming the inner sides of said jacket.

4. The structure defined in claim 3 wherein slidable 4 sealing means are interposed between the lower edges of said side walls and said jacket to prevent escape of coolant when the lower edges of said side walls are forced inwardly against the solidifying casting.

References Cited in the file of this patent UNITED STATES PATENTS 1,888,913 Erichsen Nov. 22, 1932 2,187,720 Williams Ian. 23, 1940 10 2,640,235 Hazelett June 2, 1953

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