SU1696119A1 - Method of manufacturing measuring workpieces on a multistrand continuous casting machine - Google Patents

Abstract

The invention relates to the field of foundry. The purpose of the invention is to increase the yield of metal. In a method that includes measuring the mass of a metal in a tundish, measuring the current length of the ingot for each stream and each reaching a given dimensional length, issuing a command to cut, stopping the supply of metal from the casting ladle at the time when the sum over all the stream and length ingot from the meniscus of the metal in the mold to the front end of the ingot in the sum with the length of the ingot, which will be obtained by casting the metal, which is in the tundish, minus the length of the whole number of blanks of a given dimensional length is minimal. 1 il. 1 tab.

Description

ate with

This invention relates to a foundry, namely, to continuous casting of metals on multi-strand continuous casting machines.

The closest to the technical essence of the invention is a method for producing dimensional blanks on single-strand continuous casting machines, including measuring the mass of metal in the tundish, measuring the current length of the ingot and, when it reaches the specified dimensional length, issuing a command to cut. If the need to change the tundish bucket in this method, if the ingot length is equal, obtained by recalculating the mass of metal in the tundish bucket to the ingot length for a given cross section of the mold, the termination of metal supply from the steel casting ladle

in the length of the ingot from the meniscus of the metal in the mold to the front end of the ingot, multiple of a given length of the workpiece.

The disadvantage of this method lies in the fact that it can be carried out only on single-strand continuous casting machines and cannot be used on multi-strand continuous casting machines.

According to the method of obtaining dimensional blanks, in which the streams of the continuous casting machine successively overlap at each time the ingot length is multiple to the specified dimensional length of the blanks, as in the method of controlling the final phase of casting, it is necessary to stop the streams for a sufficiently long time (up to 10 minutes or more) in which the multiplicity of the length of the ingot was achieved earlier than others, which

6s

about

Os

ABOUT

may lead to freezing of ingots in these creeks, which is the cause not only of the deterioration of the quality of the ingot, but also, possibly, of an emergency situation on the continuous caster.

There is a known method that includes stopping metal delivery from a steel casting to a tundish at an arbitrary point in time, followed by simultaneous overlapping of the streams of the continuous caster after casting the metal remaining in the tundish, In this case, a decrease in the yield of the suitable metal can be significant (up to several specified lengths of cut blanks).

The purpose of the invention is to increase the yield of metal.

The goal is achieved by the fact that according to the method of obtaining dimensional billets on a multi-strand continuous casting machine, including measuring the mass of the metal in the tundish, converting the mass of the metal in the tundish to the length of the ingot cast on the caster, measuring the current length of the ingot and stopping the metal feed when the steel ingot ladle is equal when the calculated ingot length is equal to the total of the ingot length from the metal meniscus in the mold to the front end of the ingot, which is a multiple of the given length of the workpiece, tons of metal mass in the tundish in length L of the ingot are made for the total value of the cross-sectional area of all the molds through which the casting is carried out, measurement of the length of the ingot is done separately for each stream, and the supply of metal from the pouring ladle is stopped when equality of the calculated length L of the ingot in the sum with the length of the ingot from the meniscus of the metal in the mold to the front end of the ingot, multiple of the given length of the workpiece along that stream with the number K chosen from the set from 1 to N inclusive (where N is the number of continuous caster streams along which the casting is carried out) for which the condition of the minimum of the function value is fulfilled at a given time t

N

Ј ((1gM- + D1k) M001z),

0)

eleven

tk

N

where is the summation function of all valuesI 1

X at a value from 1 to N, except for K;

li is the length of the ingot in the stream i minus the length of the ingot that is a multiple of the specified dimensional length of the workpieces at time t, mm; D1k - the length of the ingot, which is not enough

a brook K so that the ingot length along this brook at the moment of time t in total with the length L becomes a multiple of the given length of the workpiece, mm;

YMODZ is the operation of taking an integer remainder from dividing the value of Y by the value of Z.

The drawing shows a device for carrying out a method for producing dimensional blanks on a multi-strand continuous casting machine.

The device contains a mechanism 1 controlling the stopper of the casting bucket 2, a sensor 3 for the mass of metal in the tundish 4, a control computing machine (UHM) 5, a sensor 6 for measuring the current length of the ingot 7, a machine 8 for gas cutting (MF), a setpoint 9 dimensional length of the workpieces, unit 10 of the cross section of the molds 11, unit 12, the pouring of the metal grade, unit 13 of the request for changing the tundra.

Conditions for the implementation of the proposed method; equality of ingot extraction speeds of all streams; equality of space

0 sections of molds of all streams.

In the overwhelming majority of cases, in a real casting of metal on a continuous casting machine, these conditions are fulfilled.

During casting, continuous ingots 7 formed during the casting of metal along each stream rotate the measuring rollers as they move, on the axis of each of which the sensor 6 of the current ingot length 6 is rigidly fixed, which converts the linear length of the ingot 7 into a proportional number of pulses. The pulses from the sensors 6 of all the streams enter UVM 5, where, based on the data on the current length of the ingot and the known distance from the nominal

A metal level 5 of the mold 11 to the axis of the initial position of the cutters of the gas cutting machine 8 is calculated by the current ingot length measured along each stream. In case of equality by any stream of values

0 of the current and specified length of the ingot, received at the beginning of the metal casting from the setting unit 9, the UVM 5 issues a command to the MHR 8 located on the corresponding stream. The start of the cut is determined by

5 a signal about the information of the seizures of the MHR, entering the UVM. When this signal arrives in the UVM 5, the length of the cut piece is determined.

The new value of the current length of the ingot is determined by subtracting from the current length of the ingot before the beginning of the cut of the next billet the length of the cut billet. After the end of the cut, the next workpiece MGR 8 returns to its original state and waits for a new command to cut. If during the casting operation from the setting unit 13, a signal is received that the tundish must be changed, the CCU 5, based on the mass of metal in the tundish, coming from the sensor 3, determines the length L of the billets produced during simultaneous casting on all open streams of metal in tundish, according to the formula

L-TG -. (2)

p s s,

i 1

where M is the mass of the metal in the tundish, t;

p is the density of the metal, t / m3;

Si is the area of the crystallizer section along the lth stream, m,

N is the number of open streams.

The length L can also be considered the length of one billet obtained from a metal located in the tundish, but with a cross section equal to the total value of the cross sections of the molds of all open streams. Further, in UBM 5, for each open brook, the length of the ingot I is calculated, equal to the current length of the continuous ingot, minus the ingot length, which is a multiple of the specified dimensional length of the workpiece, at the time when the signal from the unit 13 arrived, using the formula

li MODU (3)

where is the current length of the continuous ingot along the i-th stream, mm;

La- specified measured length of blanks, mm;

XMODY is the operation of taking the remainder of the integer division of X by Y.

For each creek, the ingot length D I is determined, which the creek lacks at the moment of arrival of the signal from the setting unit 13 so that the length of the continuous ingot along this creek in the total with the length L becomes a multiple of the given length of the billets La by the following formula:

Ali U- (LJ + L) MODL3, (4)

where AI is the length of the ingot, which the creek I lacks so that the length of the ingot along this creek at the moment of arrival of the signal from the setting unit 13 in the total with the length L becomes a multiple of the given length of the workpieces, mm.

After that, in UBM 5 the number K is sequentially set, starting from 1 to N, and then the sum is calculated using the formula (1) and the number is determined which has the minimum value of the indicated function

The command to the mechanism 1 for controlling the stopper of the pouring ladle to stop the supply of metal to the tundish 4 UVM 5 issues, as soon as for the stream with the number K having the minimum value of function (1), the condition

(Lk + L) MODU 0, (5)

0, i

where LK is the current length of the continuous ingot along the K-th stream, mm;

L-length of blanks produced by simultaneous casting with the same speed over all open streams of metal in a tundish, mm.

After giving the command to stop the supply of metal to the tundish, the metal in the tundish,

Q is evenly and simultaneously spread on all open streams. The uniformity of casting should be ensured by the same casting speed on all the streams, which is carried out in full accordance with the technological instructions for pouring metal on a continuous casting machine.

After pouring the metal, which is in the tundish, the tundish is replaced with a temporary stop or a decrease in the speed of casting over the entire caster and continuous casting machine to a minimum. On all, a caster's caster is then formed along with, which is subsequently cut along with the ingot section in the stream before

5, those remaining after cutting the ingot in a stream into blanks of a given dimensional length. The selection of the moment when the metal enters the tundish, based on the condition of the minimum of the function (+), ensures the minimization of the total length of the sections of the ingots remaining in the strands after cutting the ingots into billets of a given dimensional length. This reduces the output of unmeasured blanks and

5 increase in yield of metal

After setting up a new tundish for casting, the metal casting is resumed with a gradual exit of the casting speed to the specified technological level.

Example. The operation of the continuous casting machine according to the proposed method, starting from the moment a request is received for replacing the tundish, suppose that metal is carried out on a four-strand caster through an tundish, the weight of the metal is 33.6 tons. The cross sections of the molds are the same and equal to 30x40 cm2. The density of the cast metal is 7 t / m3, the specified length of the measured billets is 5 m. The length of the continuous ingot: at the time of the request on the 1 st stream 30 m, on the 2nd 28 m, on the 3rd 32 m, on the 4th 29 m

Calculate the length L of the ingot obtained for each stream in case of casting the metal found in the tundish. In accordance with formula (2)

 33.6t

N

10m

7T / m3 (30x40) cm2

I 1

Calculate according to the formula (3) for each stream the length of the ingot minus the length of the ingot, a multiple of the specified length of the blanks:

  103 mm MOD 5 1 (Ymm-Hommm;

12 28 1 (I mm mm MOD 5 1 (I mm 3 103 mm;

s 32 103 mm MOD 5 103 mm

- 2 103 mm;

C 29 1 (I mm MOD 5 1 (I mm

 4 10 mm.

For each stream, formula (4) is calculated as L1:

AH 5 1 (Yamm- (30 103mm + 104mm)

MOD 5 103 mm 0 mm; similarly

Al2 2 km; D1z-3 1 (Yamm; D | 4 103mm.

Next, we calculate the value of the function (let's call it F) using the formula (1): FI- Ј (Oi + 104 + 0)

I 2,3,4

MOD 5 10) 9 KYyam; F2 Ј ((| + 44 + 2-1 (I)

I 1,3, 4

MOD 5 10) -7 KJM; Рз 2 ((h + 104 + 3 103)

 2.4

MOD 5 103) - 6 10 mm; F4 2 (Oi + 104 + 103)

I 1,2. 3

MOD 5 103) 8 1SRM.

From here we find the minimum value of the function F Pz at if 3. This means that in order to minimize the output of non-gage blanks in case of replacing the tundish, the supply of metal to the tundish should be stopped when condition (5) for the number 3 is fulfilled. In other words, to cast another AB meter of continuous ingot along each stream, and after that stop the supply of metal to the tundish. Thus, the length of the continuous ingot along the stream 3 at the time of the cessation of the supply of metal into the tundish, unless

the cutting of the workpiece is made, it will reach 35 m. Or in other words, it is required to add such amount of metal in each stream that is necessary to form a 3 m ingot of a given cross section in each stream, and then to stop the supply of metal to the tundish. In this case, the unmeasured metal residue in all the streams, resulting from

Cutting an already existing continuous ingot together with an ingot section obtained 1 before the end of the casting of the metal in the tundish will be minimal.

We illustrate the change in the quantities I) and the sum S of the unmeasured metal residue in all the streams in the event that the metal stops flowing in the tundish at each step of increasing the length of the cast

ingot. The value of S is calculated by the formula

N

S 2 (Ci + L) MODLa), (6)

i 1

where ii is the length of the continuous ingot along the i-th stream minus the ingot length, which is a multiple of the specified dimensional length of the workpiece, at the current step of increasing the length of the cast ingot, mm.

The table shows the increase in length.

cast with a discreteness of 0.5 m of ingot, starting from the moment of the request to replace the tundish bucket (after the 9th step, the values in the table are repeated).

It follows from the table that when the supply of metal to the tundish is stopped immediately after the ingot length increases by 3 m (6 steps of 0.5 m) relative to the original

In this state, the minimum value of the amount of unmeasured metal residues in all streams is obtained, where nonmeasured metal residues in each stream are obtained after cutting into dimensional blanks of a continuous ingot that is present in the stream at the initial moment, in total with the ingot section obtained in the stream the moment (the moment the request is received for the tundish scheme) until the end of the pouring of the metal from the tundish.

The essential differences of the proposed method for producing dimensional blanks on a multi-strand continuous casting machine consist in separate measuring the length of the ingot along each stream, recalculating the mass of metal in the tundish into the length of the ingot for the total value of the cross-sectional area of all molds through which the casting is carried out, and controlling the casting stopper

when the tundish is changed in such a way that the metal remaining in the tundish after cessation of the metal from the steel-teeming ladle and poured into all the streams without remainder, is added to the continuous ingots obtained earlier in the streams, so that one of the streams is continuous the ingot will be a multiple of the specified dimensional length of the workpiece, and for the rest - will be the minimum amount of non-dimensional residues.

A minimum of the amount of unmeasured metal residues obtained after cutting the resulting continuous ingots into blanks of a given dimensional length is searched for in a variety of conditions of the caster's streams, when the length of the continuous ingot along one of the streams in total with the length of the ingot produced in this stream after casting is uniform over all the stream m of metal, located in the tundish, will be a multiple of the specified dimensional length of the workpieces.

Formula (1) shows the value of the amount of unmeasured metal residues along all the streams m, except for the selected one with the number K, according to which the length of the continuous ingot in the sum with the length of the ingot obtained after casting the metal in the tundish will be a multiple of the specified dimensional length of the blanks and, therefore, the nonmeasured residue along this stream is equal to zero.

In order for the length of the continuous ingot located in the stream with the number K at the time t of calculation, in total with the length of the ingot to receive, after casting, the metal in the tundish, be a multiple of the specified length of the workpieces, it is necessary to add to the stream with the number K more A IK (for i K) metal in accordance with formula (4).

From the condition of equal speeds of metal casting along all the creek m, we get that the same amount of metal will be added to all other creeks.

Therefore, the parameter A IK appears in formula (1). The operation of taking the integer remainder was introduced in order to discard a part of the ingot along a stream with number i, which is a multiple of the specified dimensional length of the blanks. The operation of summing the off-dimensional residues along all the streams m from 1 to N, except the stream with the number K (in accordance with formula (1)), determines the sum of the off-dimensional residues of metal along all the streams m at the moment when the stream with the number K has the equality the length of the continuous ingot in the sum with the length of the ingot, obtained after casting metal from tundish, a multiple of the specified dimensional length Lj.

The positive effect of the application of the proposed method depends on the initial state of the streams of the caster (the number of streams of the caster, which is cast,

the cross-sectional area of the molds, given the measured length of the blanks and the length of the continuous ingot for each stream at the time of the request to change the tundish). For example, for the caster described in the example above, at the time of the request to change the tundish, the total value of nonmeasured metal residues after cutting continuous ingots

Depending on the choice of the moment when the metal is stopped in the tundish, the measured workpieces can range from 6 to 12 m of continuous ingot. With an average value of unmeasured metal residues in

in the given example, equal to 9 m, the average value of reduction of nonmeasured metal residues using the proposed method will be 3 m.

Claims (1)

Invention Formula The method of obtaining dimensional blanks on a multi-strand continuous casting machine, mainly in the case of a tundish replacement, which includes measuring the mass of the metal in the tundish, converting the mass of the metal in the tundish to the length of the ingot cast on the continuous casting machine, measuring the current length of the ingot and stopping the supply of metal from the steel casting machine bucket with equality of the calculated length of the ingot in total with the length of the ingot from the meniscus of the metal in the mold to the front end of the ingot to a length multiple of the specified length of the workpiece and, in order to increase the yield of a suitable metal, recalculation of the mass of the metal in the tundish into the length L of the ingot is carried out for the total value of the cross-sectional area of all the molds through which the casting is carried out, the length of the ingot is measured separately for each brook, and stopping the supply of metal from the steel-teeming ladle is carried out when it is necessary to replace the tundish with equality of the calculated length L of the ingot in total with the length of the ingot from the metal meniscus in the mold to the front end of the ingot to the length, cr a given billet length along a stream with a K number selected from sets from 1 to N inclusive, where N is the number of streams of the CCM. on which the casting is carried out, for which the condition of the minimum value of the function is fulfilled at a given time t N 2 ((li + L + AlK) MODU).  Yk where 2 (X) is the summation function of all eleven values of X at I, taking the value from I to N, except for the value of K; li is the length of the ingot in the stream I minus the length of the ingot that is a multiple of the specified dimensional length of the workpiece at time t, mm; D1k is the length of the ingot, which is not grasped by the brook K in order for the ingot length along this brook at the moment of time t in total with the length Lto be a multiple of the predetermined length of the workpieces La, mm; YMODZ is the operation of taking an integer remainder from dividing the value of Y by the value of Z.