JPS59225863A - Continuous casting method of ingot of aluminum or aluminum alloy, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a continuous casting process in which an ingot of aluminum or an aluminum alloy is continuously cast from a mold, and the strands coming out of the protrusion are cooled with water containing carbon dioxide gas. Regarding the method.

Conventional technology: When continuous casting using direct cooling mold/)s
In order to remove heat from the ingot protruding from the mold, coolant is injected onto the surface of the C ingot directly below the mold. At the start of casting, the coolant initially impinges only on the dummy block.

As a result of this, the indirect removal of heat results in a gradual hardening of the molten metal and/or a flat bottom of the cast ingot. If the dummy blocks are lowered one after another, the coolant will directly impinge on the surface of the ingot 1~, and the heat removal from the ingot will increase rapidly. The stress generated by this thermal shock becomes larger than the elastic limit of the ingot, causing permanent deformation and resulting in a convex curved shape of the ingot base.

If the tensile strength of the monthly rate is exceeded, cracks will occur in the ingot. In order to obtain an ingot with a flat base, it must not be cooled too strongly during the initial descent of the ingot.

As a proposal for this purpose, US Patent No. 3,441,079
- Avoid intermittently applying coolant to the ingot during the initial descent. However, the disadvantage of this method is that it produces an irregular heating pattern, resulting in a uniform solidification pattern.

German Patent Publication No. D [-881293956] describes a method for cooling continuously cast thin strips, plates, etc., which utilizes a mixture of water and gas produced in the form of an ejector within the mold;
Cool the ingot directly before leaving the mold, immediately
Coolant is directly injected onto a thin strip or the like to perform cooling TJ1, and indirect cooling is performed via struts 1 in the mold. By changing the air and/or water content, the depth of the liquid reservoir and/or
Or adjust the temperature of the casting lip. Since the water/air mixture is injected in the form of a mist, it is not possible to carry out specific control of the cooling, especially during direct cooling. In this patent, during indirect cooling, it is necessary to increase the amount of crystal for indirect cooling of the ingot in the space covered by the mold, and during direct cooling, it is necessary to increase the amount of air. This method does not allow continuous injection of coolant into the injector in the specific required manner.1 Another alternative to the method described above is to
There is a German patent publication DE-OS 2408285. Similar to the example above, a mixture of water and air is used to cool the steam exiting the L-rud.
Cooling water flows under pressure into the nitrogen or passages in the mold,
Cool the molding surface of the mold. The water leaving the mold directly cools the I-shaped strip. Due to the difference in cross-sectional area between the coolant outlet and the further air gap, air is drawn out of the latter with the effect of a water jet pump. This air has little effect compared to the cooling capacity of water. Furthermore, there are problems with the provision of cooling, for example, increasing the injection water loss also increases the amount of induced air. No increase in the cooling effect can be expected; the air/water mixture will only be widely dispersed.

The method described in DE-OS 2909990 is a direct quench casting of metal blocks or ingots, in which the heat removed from the ingot by means of a cooling fluid is reduced, at least at the start of the casting. For this purpose, a gas, preferably carbon dioxide, is mixed with the coolant under pressure. The gas dissolved in the coolant forms an insulating film on the ingot surface when the coolant impinges on the ingot surface. The cooling intensity decreases and the amount of heat removed decreases.

Reducing the amount of gas added to the coolant at the end of the startup process increases the amount of heat removed.

The biggest drawback of the above-described method is the cost, especially the required mixing and preparation equipment for dissolving the gas in the coolant. Furthermore, the control of cooling depends on the solubility of the gas in the liquid coolant. Solubility is determined by a variety of different parameters and varies as a function of various conditions and other variables that change over the casting period.

The invention attempts to solve the problem. The present invention provides a cooling method of the type described above, which overcomes the drawbacks mentioned above and provides precise control of the cooling method with respect to the indirect cooling period and the direct cooling period.

Means for Solving the Problems In order to achieve the stated objectives, the cooling method according to the invention consists in that the amount of carbon dioxide gas added to the water is constant during the starting phase, and the thermal contact between the ingot surface and the coolant is increased. At the same time, by increasing the water flow rate, the carbon dioxide gas in the coolant is reduced by 81 degrees.

L-Dish According to the present invention, since a water-carbon dioxide mixture of water and carbon dioxide at a predetermined temperature is used, the solubility of carbon dioxide in the cooling water does not affect the carbon dioxide effect. That is, uncertain limits such as saturated eye disease are not important.

The degree of thermal insulation provided by carbon dioxide during ingot cooling is affected by lowering the temperature and increasing the energy or velocity of the cooling water. This is possible simply by increasing the flow rate of cooling water. As the amount of cooling water m reaching the ingot surface increases, the insulating film formed by carbon dioxide gas becomes thinner, making it easier for water to penetrate. There is no film in the R-enable, and the normal cooling effect of water is fully utilized. It is also possible to stop the supply of carbon dioxide at a predetermined value of m degrees of carbon dioxide for the coolant or at the end of the start-up phase.

At the time of starting the example, the water and carbon dioxide mixture is heated by one blow of heat expansion between the indirect cooling that occurs when the molding is done and the direct cooling that occurs when the dummy base etc. is lowered. - J: It is necessary to determine the sea urchin situation ratio 1, 2, 1, this ratio is the maximum concentration value of carbon dioxide gas in water, and there are 4 difficulties in reducing the concentration by adding water. Known methods of lowering the carbon dioxide level while keeping the water level the same will result in an indeterminate amount of dissolved carbon dioxide. Before starting the process, a mixture of carbon dioxide gas and water with a specific concentration is prepared in a tank or the like, and water is added to use it during the startup process.In another embodiment, the mixture of carbon dioxide gas and water is continuously prepared in a mixing device. Prepare and continuously increase the amount of water.

Effects of the Invention By using the invoking 1-cooling control method according to the invention, an ingot with minimal cross-sectional area changes is obtained, especially in the head section of invoking 1-starting 11.1.

Patent applicant: Swiss Aluminum Limited 7-

Claims (1)

[Claims] 1. In a casting method in which an ingot 1 of aluminum or aluminum alloy is cooled from a mold with water containing carbon dioxide gas, the amount of carbon dioxide gas added to the water is kept constant during the start of casting, and the ingot A method for continuous casting of ingots such as aluminum or aluminum alloys, characterized in that increasing the thermal contact between the surface and the cooling water increases the flow rate of water and thereby decreases the concentration of carbon dioxide gas. 2. The method according to claim 1, wherein the supply of carbon dioxide gas is stopped after the start of casting or when the concentration of carbon dioxide gas in the coolant becomes less than a predetermined value.