RU2254205C1 - Method for producing measured-length billets in multistrand machine for billet continuous casting - Google Patents

Abstract

FIELD: continuous casting of metals in multistrand machine for continuous casting of billets.

SUBSTANCE: method comprises steps of measuring mass of metal in intermediate ladle; calculating length of ingot on base of metal mass in intermediate ladle; measuring current value of ingot length separately for each strand and position of metal meniscus in mold relative to measured-length of ingot; measuring and scaling mass of metal in steel casting ladle to common length of ingot while taking into account technological residues; determining quantity of measured billets according to condition of equal speed for all strands with use of given formula taking into account metal mass values in steel casting and intermediate ladles, total mass of technological residues of metal in steel casting and intermediate ladles, mass of linear meter of billet in strand, measured length of ingot, current length of ingot and position of metal meniscus in mold relative to measured length of ingot for stands; simultaneously interrupting metal supply from steel casting and intermediate ladles; then determining residual quantity of metal according to given formula; determining length of cast billet for each strand; determining additional measured billet for strand; setting maximum casting speed for such strand and then determining casting speed values for remaining strands with use of formula taking into account maximum casting speed for strand in which additional billet is to be produced.

EFFECT: lowered number of out-of-measure billets, less loss of metal yield.

1 ex

Description

The invention relates to metallurgy, namely to foundry, and more particularly to continuous casting of metals on multi-strand continuous casting machines.

A known method of producing measured billets on continuous casting machines, including measuring the mass of metal in the tundish, measuring the current length of the ingot, stopping the flow of metal from the steel pouring ladle to the intermediate bucket when slag appears in the stream from under the gate of the steel pouring ladle (Technological instruction TI 101- ST-KKTs-10-2000 “Steel casting on continuous casting machines of continuous casting machines of the oxygen converter shop”, Magnitogorsk, 2001, p.15). The end of casting in the first (first-second in the four-strand casting mode) caster continuous casting occurs when the measured length of the workpiece is cast, the remaining metal in the intermediate ladle is cast in the second (third-fourth in the four-strand casting mode) stream.

The disadvantages of the known analogue are the decrease in yield of metal due to an increase in waste resulting from the exaggerated length of the workpieces obtained in the second (third or fourth with four-strand casting mode) stream after the end of casting, a decrease in the productivity of continuous casting machines due to the increase in the duration of casting, due to the simultaneous completion of casting in individual streams, when the interval between stopping streams can reach several minutes.

The closest analogue to the claimed object is a method for producing measured billets on a multi-strand continuous casting machine, including measuring the mass of metal in the intermediate ladle, recalculating the mass of metal in the intermediate ladle to the length of the ingot, measuring the current length of the ingot separately by streams and the position of the meniscus of the metal in the mold relative to the measured the length of the ingot and the cessation of metal supply from the steel pouring ladle (RF Patent No. 1696119, B 22 D 11/16).

The disadvantage of the closest analogue is the condition that the uniformity of the casting should be ensured by the same casting speed and the same measured length of the workpieces over all streams. With this method, in the case of the simultaneous completion of the casting of metal of the previous melting from the steel pouring and intermediate ladle and casting of the subsequent melting on a new intermediate ladle or when casting the last casting ladle, a certain amount of metal remains in the steel pouring and intermediate ladles, the mass of which can reach significant sizes, and its must be returned to subsequent processing. The disadvantage of this method is to reduce the yield of metal due to an increase in waste resulting from the unmeasured length of the workpieces.

The technical task of this invention is to reduce the yield of non-dimensional billets, increase the yield of metal and achieve the total residual metal mass in the steel casting and intermediate ladles after casting is less than the mass of one workpiece, taking into account the mass of process residues.

The stated technical problem is achieved by the fact that on a multi-strand continuous casting machine, the mass of metal in the intermediate ladle is measured, the mass of metal in the intermediate ladle is counted in the length of the ingot, the current length of the ingot is measured separately by streams and the position of the meniscus of the metal in the mold relative to the measured length of the ingot, stop feeding metal from the steel pouring ladle, additionally measure and recalculate the mass of metal in the steel pouring ladle, determine the number of measured blanks by the formula:

where Q _decom - mass of metal in a steel ladle, t;

Q _prom - the mass of metal in the _tundish , t;

Q _ost - the total mass of technological metal residues in the steel casting and intermediate ladles, t;

B is the mass of a running meter of a workpiece on a stream, t;

l _merni - measured length of the ingot, m;

l _ocтi - distance to the measured length in the mold along streams, m;

stop the flow of metal from the steel pouring and intermediate ladles at the same time, then calculate the residual amount of metal according to the formula:

- целое количество мерных заготовок;Where

- a whole number of measured blanks;

while determining the length of the cast billet for each stream according to the formula:

then determine the additional measured workpiece on the stream, where

l _{manual i} = min and l _dimensional = max according to the formula

for this stream determine the maximum casting speed, and then determine the casting speed for the rest of the streams according to the formula:

where V _max - the maximum casting speed for the stream, which receive an additional workpiece.

The essence of the claimed technical solution lies in the fact that an increase in the yield and a decrease in the number of non-dimensional billets is carried out by adjusting the speed of drawing the billets for each stream separately, which allows you to pour a different number of measured billets into streams and make the most of the available metal. The necessary drawing speeds can be determined already at the beginning of casting taking into account the mass of metal located not only in the intermediate ladle, but also in the steel pouring ladle.

A specific example of the method

The work of the continuous casting machine according to the proposed method, starting from the moment of obtaining information about the simultaneous completion of casting in the steel casting and intermediate ladle.

Suppose that casting is carried out on a four-strand continuous casting machine, with a mass of metal in a steel pouring ladle of 350 tons and a mass of metal in an intermediate ladle of 35 tons. The sections of the molds are the same and equal - 250 × 1080 mm. The preset measured length for the sections is 6 m (two streams) and 5.5 m (two streams), respectively. The casting speed according to the technological instruction is 0.8 m / min (the minimum permissible along the stream is 0.6 m / min, the maximum is 0.9 m / min). The density of the solid metal is 7.8 t / m ³ .

The residual mass of the smelting at the time of the request for the simultaneous replacement of the steel casting and intermediate ladles is 210 tons in the steel casting and 35 in the intermediate ladles. The lengths of cast ingots along streams are 21, 23, 19, and 20 m, respectively. Distances to measured length in the mold along streams are 3.0; 1.0; 2.5 and 4.5 meters respectively.

The number of measured blanks for streams, in case of equal speeds for streams, calculated by the formula:

where B is the mass of a running meter of a workpiece on a stream, t;

l _mens.i - measured length of the ingot, m;

l _ost.i - the distance to the measured length in the mold along streams.

Thus, after topping up the workpieces already in the mold to a measured length, it is possible to cast four more measured workpieces for each stream, provided that the speeds are equal.

Given the mass of the measured ingot, the total amount of metal with unmeasured length will be:

M _ost = 2.106 × (4373-4) (6 + 6 + 5.5 + 5.5) = 18.06 m

To ensure the conditions for the simultaneous completion of metal casting in all streams and obtaining the maximum suitable quantity from the residues, it is necessary to redistribute the metal in such a way that the casting speed on all streams is within the permissible limit of 0.6 ... 0.9 m / min.

Therefore, we determine:

l _hand 1 = 4 × 6 + 3 = 27 m; l _{hand 2} = 4 × 6 + 1 = 25 m; l _{manual 3} = 4 + 5.5 + 2.5 = 24.5 m;

l _hand 4 = 4 × 5.5 + 4.5 = 26.5 m.

We define an additional measured workpiece on stream (N), where l _{handle i} = min and l _measure = max, given conditions corresponds to stream (N) - 2 stream.

We calculate the speed of casting along streams, based on the following conditions:

V _max = 0.9 m / min is set for the stream N = 2, for which:

Then we determine the casting speed of the remaining streams (Vi):

Settlement speeds are set for all streams, because the condition is met:

V _max ≥V _i ≥V _min ⇒0.9≥Vi≥0.6

Having established the recommended casting speeds for streams, at the end we get four measured blanks on 1, 3 and 4 streams and five blanks on 2 streams.

Thus, the use of this method allowed to increase the yield per one measured billet (12 t) by reducing the residual mass of the metal in the intermediate ladle at the end of casting to 6 t. Provided that the pulling speeds along streams are equal, as proposed in other inventions, the residual mass metal in the tundish would be 18 tons

Claims (1)

A method of producing dimensional blanks on a multi-strand continuous casting machine, including measuring the mass of metal in the intermediate ladle, recalculating the mass of metal in the intermediate ladle to the length of the ingot, measuring the current length of the ingot separately by streams and the position of the meniscus of the metal in the mold relative to the measured length of the ingot and stopping the metal supply from a steel pouring ladle, characterized in that it further measures and recounts the mass of metal in the steel pouring ladle in the total length of the ingot, taking into account the technological their residues determines the number K _zag dimensional preforms provided by the formula of equality streams speeds:

where Q _decom - mass of metal in a steel ladle, t; Q _prom is the mass of metal in the tundish, t; Q _ocm is the total mass of technological metal residues in the steel casting and intermediate ladles, t; B is the mass of a running meter of a workpiece on a stream, t; l _mens.i - measured length of the ingot, m; l _ocmi - the current length of the ingot and the position of the meniscus in the mold relative to the measured length of the ingot along the streams, m, at the same time stop the flow of metal from the steel pouring and intermediate ladles, then calculate the residual amount of metal M _OST according to the formula:

Where

- a whole number of measured blanks, in this case, determine the length l of the _{handle i of the} cast billet for each stream according to the formula:

then determine the additional measured workpiece on the stream l _{handle N} , where l _{handle i} = min and l _dimensional = max, according to the formula:

for this stream set the maximum casting speed, and then determine the speed V _i casting for the rest of the streams according to the formula:

where V _max - the maximum casting speed for the stream, which receive an additional workpiece, m / min.