US2791812A

US2791812A - Apparatus for the continuous and semicontinuous casting of metals

Info

Publication number: US2791812A
Application number: US392972A
Authority: US
Inventors: Paul E Dangelzer; Trapied Guy
Original assignee: CIE FRANCAISE DES METAUX
Current assignee: CIE FRANCAISE DES METAUX; FRANCAISE DES METAUX Cie
Priority date: 1953-01-23
Filing date: 1953-11-18
Publication date: 1957-05-14
Anticipated expiration: 1974-05-14
Also published as: FR1072748A

Description

May 14, 1957 P. E. DANGELZER ETAL APPARATUS FOR THE com-mucus AND SEMI-CONTINUOUS CASTING OF METALS Filed Nov. l8, 1953 United States Patent APPARATUS FOR THE CONTINUOUS AND SEMI- CONTINUOUS CASTING OF METALS Paul E. Dangelzer, Saint-Denis, and Guy Trapied, pastelsarrasin, France, assignors to Compagnie Francaise des Metaux, Paris, France, a French company Application November 18, 1953, Serial No. 392,972

Claims priority, application France January 23, 1953 2 Claims. (Cl. 22-572) In the continuous, or semi-continuous, casting of metals there is used a bottomless ingot mould, generally of small height, which is cooled by a liquid circulating through the mould. Many proposals for eifecting the solidification and cooling of the casting as it is formed and leaves the mould have been made, it being well understood that such cooling must take place under selected conditions in order to obtain sound metal and a desired crystallisation having the required characteristics (grain size and orientation), either in order to facilitate the subsequent working of the metal or to obtain a finished product having particular mechanical, physical and chemical properties.

Thus, in some known apparatus, the mould, whether in motion or not has holes or slots in its lower portion to permit the cooling liquid, after it has cooled the mould it streams from to act directly on the casting in the course of solidification.

In other apparatus, the mould is extended at the bottom to form a chamber in which the cast metal is in direct contact with the cooling liquid.

If necessary, a part of mould may be heated.

It has also been proposed to provide below the mould one or more spouts from which jets of liquid are suitably directed on to the solidified casting, in order to get a high cooling rate.

In the casting of hollow articles (for example, roughedout articles for tubes), the mould comprises a cooled core from the bottom of which a cooling liquid is projected into the cavity of the casting.

However, the desired object of obtaining sound metal and of effecting a predetermined crystallisation is not always satisfactorily achieved with the known apparatus due broadly to the lack of a means for controlling the cooling rate: more specifically the cooling effect is rendered uncertain because, in part, uncontrolled splashing of the liquid occurs at the points of impact of the cooling jets and the liquid trickles along the casting and exerts a cooling action at regions of the casting which need not be further cooled. It is difficult to control the acfion of the cooling liquid trickling along the casting, because little is known of the movements of this liquid, and consequently of the temperature thereof on cont-act with the metal.

The object of the present invention is to provide improved means for solidifying and cooling the ingot continuously discharged from the mould by projecting the .cooling liquid divided not into continuous jets or streams, .but into very small spheres, particles or droplets.

Apparatus according to this invention gives the opportunity to eliminate the above explained disadvantages of known methods, the condition being that the liquid spheres or particles projected upon the ingot should be small enough in diameter to be fully evaporated, thus eliminating any trickling down of liquid along the ingot and in addition the mist which is encountered when reducing the intensity of continuous liquid streams hitherto .used.

As a consequence, only the places of the ingot, upon which the spheres of liquid are projected to, being cooled without any further trickling of liquid, it is possible to obtain any wished solidifying and cooling rate depending upon the cast metal and the further use of it, by conveniently selecting the liquid itself and its atomisation.

In the casting of hollow billets, the cavity in the casting may be cooled too by projection of small spheres of liquid, from the core of the mould.

Possibly, the small liquid spheres or particles projecting apparatus may be accompanied by common liquid jets projecting apparatus in order to achieve the cooling.

The present invention has also for an object the provision of apparatus characterized by convenient arrangements under the bottomless mould of fittings projecting adequate size spheres of liquid to adequate parts of ingot.

A further object of the invention is the provision of means for obtaining improved metals and alloys.

Throughout this specification and the accompanying claims, the term ingots includes all types of products which can be continuously or semi-continuously cast in an ingot mould, whether they be billets of circular or square cross-section, plates, hollow roughed-out articles or the like.

The description which follows with reference to the accompanying drawing is given by way of example only to enable the manner in which the invention can be carried into efiect to be readily understood. In the drawing Figure 1 shows diagrammatically in vertical section a mould withsmall liquid spheres projecting apparatus in accordance with this invention, and

Fig. 2 shows certain details of construction of the apparatus of Figure 1 and to a larger size.

In the drawing: the mould 1 is of the type compn's ing a cooling water jacket 2 which surrounds the inner wall of the mould and which is closed so that the water contained in the said jacket has no direct contact with the cast metal. The mould is open at the top for the casting of the liquid metal. It is also open at the bottom, through which the metal ingot 3 continuously issues, the said ingot being drawn out by rollers or resting with its base on a movable member (not shown) which is moved downwardly. The said movable member may comprise, for example, a metal plate on which the ingot rests and a tablesupporting the said plate, mechanical or hydraulic means being associated with the table to control downward movement of the plate.

At the outlet of the mould are disposed banks of water-

atomising ducts

4 and 5.

In the illustrated example, the streams of water escaping through calibrated orifices [are atomised by jets of air or other gas under pressurewhich are directed across the water streams and substantially at right angles relatively thereto so as to break up the water streams into very fine droplets the air and water orifices being so directed that the water droplets are projected on to selected areas of the ingot 3.

In the case of the bank of atomisers 4, the details of construction of which are more clearly shown in Figure 2, a compressed-air duct 6 lies between two

water ducts

7 and 8.

Ducts

6, 7, 8 are brazed together at 9, the brazing metal being machined to produce clean surfaces 10-11, in which there are formed nozzles or holes tor the passage of water and air, indicated by 12 and 13 respectively. The

ducts

7 and 8 are each formed with a series of nozzles or holes 12 for the discharge of the water and the air duct 6 has two series of nozzles or holes 13 juxtaposed to the holes 12 and directed perpendicularly thereto. By suitably graduating the air pressure in the duct 6 in relation to the pressure of the water in the

ducts

7 and 8, the air jets leaving the holes 13 can Patented May 14, 1957' 3 be made to break up the water streams leaving the holes 12 into fine droplets and to direct the droplets substantially in the direction of these air jets on to the ingot 3.

In the particular example illustrated in the drawings the bank 4 projects the water droplets as curtains f and f1. Curtain f is directed on to the bottom of the mould, that is, both on to the ingot leaving the said mould and into the annular gap which tends to form between the ingot and the internal wall of the mould as a result of the contraction of the cooling metal. The curtain h is directed on to a somewhat lower point of the ingot. The bank 5 is similarly designed, but comprises an air duct 6 adjacent only one water duct 7 and the curtain of droplets fz which it produces acts on an area of the ingot which is situated a little lower than the area previously mentioned.

Naturally, this arrangement is only to be regarded as an example and it will be appreciated that the construction, the number and the distribution of the banks, as well as the positioning of the nozzles and of the water droplets curtains may be varied to produce a desired cooling efiect, it being possible to obtain such efiects with much greater certainty than in the arrangements at present known, since, owing to the projection of the water in the form of fine droplets thewater is converted into vapour in the area of the ingot with which the drops actually come into contact, without any liquid trickling along the ingot and consequently without the cooling action being carried into areas where it is not required.

The cooling is effected by withdrawing from the ingot the heat required for converting the water into vapour, which may in some cases be dry and unsaturated, so that the more or less thick mist which generally surrounds the ingot is eliminated or reduced, the visibility of the ingot thereby being improved and observation of the operations facilitated.

If the ingot 3 is a solid of revolution, the banks of atomisers may themselves be in the form of a solid of revolution about the axis of the ingot, Figure 1 then being a centre section. In the case of ingots not having the form of a solid of revolution, the atomising ducts may be arranged along the faces of the ingot, for example, on either side of the ingot if the latter is a plate.

The method of atomisation described, in which air and water are fed through separate pipes, may naturally be replaced by any other known method of atomisation. It is not'essential to employ a compressed gas to atomise the water, and the atomisation of the water may also be effected by feeding it under sufficiently high pressure and discharging it through fine orifices.

It is advantageous for the water to be sufiiciently pure to prevent blockage of the

nozzles

12, 13 with sediment. It will therefore be expedient in many cases to provide water-purifying devices on the upstream side of the bank of atomisers. Shut-cit valves and expansion valves may also be combined with the 'ductsto regulate the delivery of liquid and air respectively.

One advantage of the invention resides in that the annular cavity formed by the contraction of the metal between the mould and the moulded product, from the instant when the solidification ring is formed, can receive the water droplets without any danger of the liquid rising along the wall of the mould. The intensity of the cooling may therefore .be adjusted at will as a function of the elongation of the issuing product with a view to the results to be obtained and particularly for purposes of slow solidifying and cooling, from the instant when the metal becomes detached from the mould until the instant when the cooling speed-has no effect on the physical or chemical characteristics of the metal.

It follows that the crystallisation obtained may be controlled at'wi-ll within wide limits. Moreover, the application of atomised liquid to the area in which the metal becomes detached from the mould thus. avoids partial remelting of the solid crust and therefore the well-known phenomena of sweating and blow-holes.

What we claim is:

1. Apparatus for the continuous and semi-continuous casting of metals, comprising a mould into which the metal to be cast is poured and from which the cast ingot is discharged, a duct to convey a liquid for cooling the ingot, nozzles communicating with said liquid duct for discharging streams of the liquid towards the ingot, a duct to convey air under pressure, said ducts being adjacent one another, and nozzles communicating with the air duct for forming air jets, the former nozzles and the latter nozzles being so oriented relatively to each other that the liquid streams and air jets intersect before reaching the ingot whereby a mist of atomised liquid is applied to the ingot.

2. Apparatus as claimed in claim 1, further comprising a second liquid duct, adjacent to the air duct, said air duct lying between the two liquid ducts, further nozzles communicating with said second liquid duct for discharging funther streams of the liquid towards the ingot, and further nozzles communicating with the air duct for forming further air jets, said further streamforming nozzles and air-jet-forming nozzles being so oriented relatively to each other that the further streams and the further air jets intersect before reaching the ingot.

References Cited in the file of this patent UNITED STATES PATENTS 629,480 Uehling et al. July 25, 1899 2,301,027 7 Ennor Nov. 3, 1942 2,414,269 Nicholls Jan. 14, 1947 2,651,821 Chadwick et al. Sept. 15, 1953 2,705,353 Zeigler Apr. 5, 1955 FOREIGN PATENTS 887,268 France Aug. 9, 1943 813,755 Germany Sept. 17, 1951