SU595063A1 - Method of detecting voids during the continuous casting process - Google Patents

Description

one

The invention relates to metallurgy, and more specifically to the continuous casting of metals and alloys.

There is a known method for detecting breakthroughs in a metal, which includes radiating the mold with radioactive radiation and determining the position of metal meniscus 1.

The disadvantage of this method is the low accuracy of the determination of the moment when a metal breakthrough is formed under the installer. This is due to the fact that the withdrawal of the Mennsk metal from the zone of transmission can be caused, besides the breakthrough of the metal, by an increase (decrease) in the speed of drawing or by increasing the supply of metal to the mold.

In order to improve the accuracy of determining the moment of metal breakthrough under the crystallizer, when the metal meniscus is lowered by an amount equal to 0.3-0.4 lengths of the translucency zone, the speed of lowering the 1st I meniscus is measured and when reaching the speed of lowering 50-200 iMM / sec, stop1, Iodachu metal.

Studies have shown that the breakthrough of metal from crystallizers of small cross section leads to a more rapid change in the position of the metal meniscus in the translucency zone than in crystallizers of a large cross section.

2

Measurements of the lowering rate of the meniscus in crystallizers of various cross sections at metal breakthroughs show that oia varies between 50–200 mm / s, inversely proportional to the cross section of the crystallizer.

Measurements of the rates of change in the position of the metal in the same crystallizers when the speed of ingot extrusion or the supply of liquid metal varies, show that the speed varies between 5-10 mm / s or 10-20 times less than when the metal breaks through.

Below give the justification of the proposed method.

In the process of continuous casting, liquid steel of the type ZSP is injected into the mold with an interdisciplinary section of 250X X 1550 mm and the ingot is drawn at a speed of 0.8 m / min. The position of the meniscus of the metal is monitored by means of radioactive radiation through the crystallizer of the crystallizer, for example, at the distance of 300 mm from its upper thorium. But the intensities of the y-radiation perceived by the counter determine the position of the meniscus of the metal in the crystallizer and, depending on its position in the zone of the glow, regulate the speed of drawing of the ingot and iodine of the liquid metal. At the same time striving to maintain

meniscus metal at a distance of 150 mm from the top of the mold.

During the casting process, in the part of the zone of penetration, which is 0.3 of its length or 90 mm, the velocity of the oluscan} 1 meniscus of the metal is measured.

When the metal is burst under the crystallizer, due to, for example, slag inclusion in the ingot shell, the meniscus lowering speed reaches 50 mm / sec. This increase in the speed of lowering the meniscus is fixed by means of a differentiator or a derivative calculating unit included in the automatic control system of the tundish stoppers of the n draw stands. The signal produced by the differentiator enters the actuators, the supply of the liquid metal is stopped and the impregnating cell stops.

The length of 105 mm, or 0.35 of the area of transmission, in which the rate of meniscus irrigation is measured, is chosen when casting ingots. Section m 150X800 mm with a speed of 1.0 m / mi. The meniscus descent rate at break is 100 mm / sec.

The length of 120 mm or 0.4 of the section of the zone of transmission in which the rate of lowering of the meniscus is measured is selected when casting ingots with a cross section of 200 x 200 mm at a speed of 1.2 m / min. The lowering speed of the meniscus is 200 mm / sec. The length of the region of the x-ray region where the measurement is made is 0.3-0.4 of its length.

The advantages of the proposed method are: the time from the formation of the breakthrough to the stop is reduced; the supply of metal to the mold is reduced, the accuracy of the determination of the momentum of the formation of the breakthrough of the metal under the mold is improved. As a result, the amount of metal flowing out of the ingot is reduced, the equipment in the secondary cooling zone is less filled with liquid metal, the time to reduce the consequences of breakthroughs is reduced by 20-30%, which leads to an increase in plant productivity.

Claims (1)

Invention Formula The method of detection of breakthroughs of the metal in the process of continuous casting, including the transmission of the mold with radioactive radiation and determination of the position of the metal meniscus, characterized in that, in order to increase the accuracy of determining the moment of metal breakthrough under the crystallizer, when the metal meniscus is lowered by an amount equal to 0.3-0.4 the length of the translucent zone, the lowering speed of the meniscus is measured and upon reaching the lowering speed of 50–200 mm / s, the supply of metal is stopped. Information sources, taken into account during the examination 1. Patent of Germany No. 1290303, cl. aib 11/10, 1969.