SU789217A1 - Metal continuous casting method - Google Patents

Description

one

The invention relates to the field of metallurgy and can be used in the continuous casting of metals.

There is a known method of continuous casting of metals, including pouring metal 5 into the mold, drawing an ingot with a variable speed from it, maintaining and guiding the ingot with rollers, cooling the ingot with water sprayed by nozzles, as well as changing the cooling intensity along the secondary cooling zone depending on the draw rate from the maximum value under the crystallizer to the minimum at the end of the cooling of the ingot. In this case, the torches of water are broken up into separate parts by installing grids above the ingot surface in the path of the water torches. II.20

The closest to the present invention is the method of continuous metal casting, including pouring it into the mold, drawing an ingot of variable speed from the mold, maintaining and guiding the ingot using rollers, as well as cooling it with water sprayed in the form of torches by nozzles, change in specific water consumption along the zone - 30

secondary cooling, depending on the draw rate, from the maximum value under the crystallizer to the minimum - at the end of the cooling zone. At the same time, part of the ingot surface is shielded in the area of its edges by means of shields installed on the ingot surface. It is possible to move the flaps near the ingot surface, as well as change their distance to the cooling surface 2}.

A disadvantage of the known methods is the high intensity of cooling of the middle part of the ingot surface located between the plates. B. At the same time, cooling the surface of the ingot in the region of its fins is not enough. As a result, a theoretically necessary pattern is the change in water flow and uniform temperature distribution around the ingot perimeter, as a result of which significant temperature gradients and thermal stresses occur in the ingot casing, leading to ingot cracks, as well as to an increase in the amount of trimmings of continuously cast ingots.

The purpose of the invention is to improve the quality of continuous ingots.

This goal is achieved by the fact that in the method involving pouring metal into the mold, drawing an ingot with a variable speed from it, maintaining and directing the ingot, as well as cooling it with water, sawn into torches by nozzles, changing the specific water flow along the secondary cooling zone depending on from the speed of drawing from the maximal value under the crystallizer to the minimum - at the end of the zone, and the regulation of the intensity of cooling during the casting process; that 10-30 cycles per minute is directly proportional to the ingot drawing speed.

Example. In the process of continuous casting, low-alloy 17G1S pipe steel is poured into the mold and the ingot is drawn with a cross section of 250x1700 mm at a speed of 1.0 m / min. In the secondary cooling zone, the ingot is supported and guided with rollers and cooled with water sprayed by flat-spray nozzles grouped in 5 nozzle sections with a length of 1.0; 1.0; 1.5; 2.0 and 2.5 m respectively. In the nozzle sections, the specific water consumption is set at 8.0; 6.0; 5.0; 4.0 and 3, respectively, by varying their exponential law from the maximum value under the mold to the minimum at the end of cooling. In the 1st and 2nd nozzle sections, flat-nozzle nozzles are installed with a productivity l ,, in the 3rd - 0.8 m / h, in the 4th 0, 6, and in the 5th - 0.4 m / h . The opening angle of the nozzle plugs is 90 degrees, and they are set at a distance of 450 mm from the ingot surface. Metal nozzles are installed in front of the nozzles at a distance of 50 mm from the nozzle; they are able to move in the transverse direction to the torch under the action of a special actuator including hydraulic cylinders. The frequency of movement of the flaps is set within 20 cycles per minute. When moving, the flaps periodically overlap the plumes of water from the nozzles, reducing the intensity of the cooling of the ingot surface and reducing the amount of water falling on the ingot by 3 times. The remaining 2/3 of the water from each nozzle is diverted to the side with the help of shields and not ingested. As a result, a theoretically required soft secondary cooling mode is provided, changing from the maximum value under the crystallizer to the minimum at the end of the cooling zone.

As the pulling rate decreases to P, 4 m / min, the frequency of movement of the flaps is reduced to 10 cycles per minute. At the same time, the intensity of cooling is reduced in sections to 5.0; 4.0; 3.0; 2.5 and 2.0 respectively

With an increase in the speed of drawing up to 1.6 m / min, the frequency of movement of the flaps is increased to 30 cycles per minute. At the same time, the cooling intensity or the specific flow rates of water increase in sections to 11.0; 8.0; 7.0; 5.5. And 4.0 m respectively.

The decrease in the frequency of movement of the plates with a decrease in the speed of drawing is explained by the fact that at low speed of drawing on the same level of the secondary cooling zone the thickness of the shell of the ingot increases. With a large thickness of the shell of the ingot, its heat inertia and thermal resistance increase, as a result of which a relatively longer time is required for the action of water jets on the surface of the ingot.

The increase in the frequency of movement of the plates with an increase in the rate of pulling is due to the fact that, at a high pulling rate at the same level of the secondary cooling zone, the thickness of the ingot shell decreases. With a small thickness of the shell of the ingot, its heat energy and thermal resistance are reduced, as a result of which a relatively shorter time of impact of the jets of the foam on the ingot surface is necessary.

The application of the proposed method allows to avoid the occurrence in the ingot shell of significant temperature gradients and thermal stresses that exceed permissible values. A decrease in the frequency of movement of the flaps below 10 cycles per minute leads to overcooling of the ingot surface.

Increasing the frequency of movement of the flaps for more than 30 cycles per minute leads to overheating of the ingot surface.

The proposed method improves the stability of the crystallization of the continuous ingot system, eliminates local overheating and overcooling of the surface areas of the ingot and allows the use of nozzles with a large nozzle diameter, which increases their reliability in operation.

Claims (1)

Invention Formula The method of continuous metal casting, including pouring it into the mold, pulling the ingot out of the mold with a variable speed, maintaining and guiding the ingot, 5 7892176 as well as its cooling with water, sprayed over the torches of water with nozzles peelable in the form of torches, that is 10-30 cycles per minute, just changing the specific flow rates of water proportional to the heat of the secondary cooling of the ingot. depending on the speed of drawing. from the maximum value under the crystal, Information sources, by the lesser to the minimum - at the end5 taken into account during the examination Zones and intensity control1- Accepted by Japan cooling, different 49-659, cl 11 b 091 1974 In order to improve quality. Austrian patent number 332014, cl. ingots, in the process of casting periodi-31, 8/02, 1976.