US2651821A - Continuous or semicontinuous casting of metals - Google Patents

Description

Sept. 15, 1 3 R. CHADWICK ETAL 9 1 CONTINUOUS OR SEMICONTINUOUS CASTING OF METALS Filed Nov. 20. 1950 INVENTORS.

Richaz'yd Ckadwjcicfi T @7122 Fmncr'sJip hbs, 1

M y flld /ywm ATTORNEYS.

F'atentecl Sept. 15, 1953 CONTINUOUS R SEMICONTINUOUS CASTING or METALS Richard Chadwick, Kings, Norton, Birmingham,

and John F. Hobbs, Birmingham, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Application November 20, 1950, Serial No. 196,542 In Great Britain November 24, 1949 Claims.

This invention relates to the continuous or semi-continuous casting of metals and alloys and more particularly to improvements in the method of cooling the cast product.

In one method of continuous casting (the term continuous casting as used hereinafter includes both strictly continuous and semi-continuous processes) molten metal is poured into a short open mould and the emerging cast product is subjected to direct cooling by means of a water spray. This has many advantages such for example as the production of fine grain and reduction of segregation, but the disadvantage is that internal stresses are set up due to the steep temperature gradients present in the cast product. This may be avoided without losing the advantages of direct cooling by limiting the amount of heat extraction by suitable interruption of the cooling, intensive cooling having been found to be necessary only in the first stage. One method of accomplishing this is by means of a container arranged to fit around the emerging casting at a suitable position and adapted to collect the coolant. The casting passes through an aperture in the base of the container provided with for example rubber or asbestos packing to prevent leakage of coolant through the joint. It has been suggested to provide a compressed air spray below the container for the purpose of stripping oil from the casting any coolant that has succeeded in penetrating the joint. A coolant collector of this type is however not very satisfactory since irregularities in the surface of the casting soon effect deterioration of the liquid-tightness of the joint. A simpler alternative that has been proposed is to dispense with the collector and rely upon a compressed air spray to strip the coolant from the casting at the required level. We have however found that this method also is open to objection since when using a single ring of air jets, however placed, a small variation in air pressure induces a considerable variation in the water level, causing departure from the optimum cooling conditions, and the object of this invention is to provide a simple and effective method of maintaining the coolant level at the optimum position.

According to the present invention therefore, in a continuous casting process of the kind described employing limited direct cooling of the cast product, we provide an improved cooling system comprising a coolant spray and a pair of compressed air sprays a short distance apart acting in opposed directions in such manner that the coolant is stripped off from the casting at a substantially constant level maintained at a point between the positions of impingement of the two air sprays.

The sprays may conveniently take the form of a ring (or other suitable section of corresponding shape to the casting) of jets arranged around the emerging casting.

Preferably a drip screen is employed in conjunction with the air sprays to facilitate removal of the coolant stripped from the casting. This screen is preferably arranged with only a narrow clearance between it and the casting and the lower air spray is preferably arranged so that its point of impingement is substantially level with the top edge of the screen.

The invention is illustrated but not limited by the accompanying diagrammatic drawing representing a vertical section through part of a continuous casting machine, in which i represents a, continuously cast ingot emerging from the mould 2. A ring of water sprays 3 supplies coolant to both the lower end of the mould and the emerging metal, as indicated. An upper ring 4 and a lower ring 5 of air jets are connected to a source of compressed air and adapted to deliver jets of air in such manner that they impinge on the casting just above and just below at the level AA respectively. This level represents therefore substantially the lowest level at which coolant is in direct contact with the casting. A drip screen 6 is attached to the lower ring 5 in such manner as to facilitate removal of the coolant stripped from the casting by the air jets.

We claim:

1. In apparatus for the continuous or semicontinuous casting of metals and their alloys having means for limited direct cooling of the cast product, the improvement comprising a coolant spray disposed around said casting for spraying a coolant directly upon the peripheral surface of the casting, a pair of vertically spaced compressed air spray rings disposed around said casting below the said coolant spray, said air spray rings having openings therein disposed to direct air in opposed convergent directions toward a region on the casting intermediate the levels of said compressed air spray rings so that the coolant is removed from the casting at a substantially constant level between the positions of impingement of said air sprays.

2. Apparatus as claimed in claim 1 in which the said spray rings comprise a ring of jets.

3. Apparatus as claimed in claim 2 in which an inwardly inclined drip screen. is disposed around said casting and adjacent thereto at a point between the vertically spaced compressed;

air spray rings to facilitate the removal of the coolant displaced from the casting by said air} sprays.

4. Apparatus aS claimedinclairnfi inwhich the lower of said air sprays impinges said casting:

at a point substantially level with the top edge of said drip screen.

5. Apparatus as claimed in claim 4 in which said drip screen is attached to the lower of said spray rings.

RICHARD CHADWICK. JOHN F. HOBBS.

References Cited in the fileof, this patent UNITED STATES PATENTS

Images