SU1576228A1 - Method and apparatus for automatic controlling of temperature of ingot surface in continuous casting - Google Patents

Abstract

The invention relates to the continuous casting of metals and other materials in ferrous and non-ferrous metallurgy, in particular to the control of the temperature of the surface of a continuous ingot in automatic control systems of a continuous casting machine. The purpose of the invention is to expand the functionality. The essence of the method consists in continuously measuring the surface temperature of the ingot with a movable pyrometer, the spot of which is continuously reciprocating across the ingot, the width of which is divided into sections, without displacing the pyrometer along the technological axis, the period and scanning speed being chosen so that the scanned area of the pyrometer surface for any time interval was not less than the surface area, which was released for the same time interval from the secondary cooling bunker, in averaging obtained temperature values for each of the selected areas, in the compilation of a matrix of temperature values for all sections of several transverse bands and in the determination of the matrix of longitudinal and transverse gradients on the basis of this matrix. 2 sec. f-ly, 3 ill.

Description

The invention relates to foundry, namely, to continuous casting of metals and other materials, and can be used in automatic control systems for continuous casting machines.

The aim of the invention is to expand the functionality.

FIG. 1 is a block diagram of the device; in fig. 2 — sighting spot scanning path; in fig. 3 - scheme for calculating the relative error

The device (Fig. 1) contains a pyrometer 1, a pyrometer displacement actuator 2, an integrator 3, a timer 4, four dividers 5-8, a multipoint recorder 9, a pyrometer sighting width setting unit 10, a pyrometer viewing angle setting unit 11, a number setting sections number 12, a casting speed sensor 13, a total ingot length sensor 14, two limit switches 15 and 16, a matching circuit 17 and an element OR 18, moreover, the output of the setting unit 10 of the viewing band width pyrometl i

about

N2 GS

00

pa connected to the first input of the second divider 6, the second input of which is connected to the output of the sensor 13 speed casting, and the output of the second divider 6 is connected to the second input of the third divider 7, the first input of which is connected to the output of the unit 11 of the viewing angle of the pyrometer, and the third divider 7 connected to the first input of the drive 2 moving the pyrometer, the second and third inputs of which are connected to the outputs of the first 15 and second

16 end switches, respectively, whereby the actuator 2 informs pyrometer 1 of a swinging or reciprocating motion, in addition, the output of the second divider 6 is connected

to the first input of the fourth divider 8 to the second input of which the output of the setting device 12 is connected to the number of sections of the partition, and the output of the fourth divider 8 is connected to the first input of the circuit

17 matches, to the second input of which the output of timer 4 is connected, and the output of the matching circuit 17 is connected to the first input of the element OR 18, to the second

and the third inputs of which are connected to the outputs of the first 15 and second 16 limit switches, respectively, and the output of the element OR 18 is connected to the input of timer 4, to the fourth input of the multipoint recorder 9 and to the first input of the integrator 3, to the second input of which the output of the pyrometer 1 is connected, and integrator 3 output is connected to the first input of the first divider 5, the second input of which is connected to the output of timer 4, and the output of the first divider 5 is connected to the fifth input of the multipoint recorder 9, to the first input of which is connected the output of sensor 14 of total length ingot, n second and third input multipoint registrar 9 are connected outputs of second 16 and first limit switch 15, respectively.

When the pyrometer sighting spot moves along the ingot at a speed V (in the reference system associated with a fixed ingot), the scanning path is a zigzag line. The surface area scanned by the pyrometer for the period T (shaded)

S L-r. B, (1) where L is the distance from the pyrometer to

ingot surface;

D is the indicator of pyrometer sighting; Ln - spot diameter as well as width

sight strips; b - ingot width.

The surface area released during the period T from the secondary cooling bin:

U

C0

Sz vtb

(2)

de V - actual casting speed.

Then according to the method S S2, therefore L p b VTb, whence

V 2b 2bV

I,

R

and ch. jL u v

T L7Lp

(3) (4) (5)

where U, CO - linear and angular velocity of the pyrometer during its reciprocating or swinging motion, respectively. The width of the ingot (Fig. 2) is divided into

which 1O is chosen

2 sections, the length of each of

LL With

ten

lower values of 10 become ineffective in integrating temperature values over this area, since inertia of the pyrometer sharply limits the number of terms of the sum during integration, and at large, it is difficult to identify temperature values of scale, rather than ingot. The outcome of this

five

P,

0

ent (-b-)

Lp

(6)

five

0

However, with the passage of each of the n ,, sections of length 10 during the time t0

(7)

2. t

2p pyrometer having inertia b1,

must fix at least two temperatures (for one, the averaging of the temperature value makes no sense) even at the maximum casting speed (and pyrometer speed), i.e. 2 Ј Ј t0 or Ј T / 2, where T lp / Od, where it follows

.LJL

n2Ј

4 (8)

The average value of the temperature of the ingot according to any one of the n sections is defined. -Mewdt

(9)

where 0 / is the average temperature value of the 5th j-ro of the section of the transverse strip being scanned; 0 (t) - current temperature value

surface ingot. When analyzing the temperature of the ingot floor are limited to n, transverse

stripes wide

Ur

each

ten

each transverse band corresponds to pg of mean values of temperature. All values of Hz bands n2 plots form the temperature matrix

b

Y (tf

22

year

g, pg

(YU)

9P, A,

 P ,, Pg.

When the pyrometer reaches the extreme position, the matrix is corrected: the nth row is assigned the values of (n, -1) -th row, (n, -1) -th row - values of () -th row, and so on, the values of the first row are zeroed, preparing cn to record regular band temperature values:

9 ;: i 6i-i, j when i

  0 when i

t 1

- one

The matrices in

in, and bg of temperature gradients is the same moment.

Based on this matrix, scale points are recognized. Scale points are determined by the second row of the temperature matrix 0 as the failure of one matrix value compared to the specified value, provided that all the neighboring matrix values correspond to the specified temperature values. After recognition of the scale points, the temperature matrix is corrected: instead of the low temperatures of the scale, the values of the arithmetic average of the neighboring patric values surrounding the scale point are substituted, after which

matrix of longitudinal b, and transverse 0Ј gradients (Fig. 2):

0

H

X

(12)

 J

y- 5 oh ury

about

)

ten

15

20

25

thirty

35

40

45

50

55

where is x

b 2n

- (2J-1) if 1-

the strip was scanned from left to right;

- (2 (n2-j) + 1 if the 1-ni band was scanned from right to left, (13) where 9; j are the values of the corrected

matrix 9

The analysis of the values of the matrices 9, 9, and in% makes it possible to recognize potentially defective areas and areas of uneven cooling caused by a distortion of the torches of the nozzles of the secondary cooling zone with their partial clogging. Potentially defective are the areas for which several neighboring values of matrix temperature 0 are substantially less than the specified ones, as well as those for which the values of the longitudinal or transverse gradients exceed the maximum permissible values. Knowing the distance from the temperature control section to the cutting unit along the technological axis, as well as the total length of the ingot at the time of the occurrence of a potentially defective section, this section (after additional analysis before cutting) can be cut as unfit. Plots of uneven cooling can be recognized by a significant increase in temperature values in some columns of matrix 0 by a constant value, with a corresponding significant decrease in temperature values in some other columns of matrix 0 by a constant value compared to a given temperature field, as well as in corresponding columns of the matrix U / transverse gradients. Temperature and gradient information is used to control the cooling mode of the ingot to prevent defects.

The scheme shown in FIG. 3 illustrates the calculation of the relative error in determining the moments of passage of the j-ro portion across the ingot during a swinging movement of the pyrometer compared with its reciprocating movement. The maximum error is when passing the extreme sections,

for example, p. th, and it is equal to the length of i (cutting CC, since Sun b / n2 is the length

plot with reciprocating motion, and the sun - with swinging. From the DRAWS, the pyrometer viewing angle and the angle of view of the partition are found:

; FAB 2arctg (b / 2L)

LCAB

ul - arctg (b / 2L)

(14)

According to the sine theorem, the segment BC is found in / 3 ABC, which corresponds to the angle of view of the partition area oi:

L sin

The sun

cos -Јdcos (-Ј - 1)

(15)

Sun -, - n2

whence the relative error

C-BC - BC,.,.

 .(sixteen)

The device works as follows.

The operator sets the initial data, input from the unit 11 of the viewing angle pyr2b, „

meter value - from master 10 wi-L

The range of the pyrometer sight is L0 and the value of 2п2 from the setting unit 12 of the number of divisions. The device starts to work from the moment of touching the stream. The signal from the casting speed sensor 13 is fed to the second input of the divider 6, the first input of which receives a signal from the target bandwidth setting 10, corresponding to LO, the output of which generates a signal corresponding to the pyrometer movement period T Lp / V (formula (5) ) ..)., This signal from the output of the divider 6 is fed to the second input of the divider 7, the first input of which receives a signal from the unit 11 of the viewing angle of the pyrometer, corresponding to

- 2b.

shchi -, at the output of which a “2b, Lp” signal is formed, the signal corresponding to - / -

2bV „„ ---- - pyrometer angular velocity

L-lp

at his swing. This signal arrives at the first input of the actuator 2 for moving the pyrometer, and signals from the first 15 and second 16 limit switches, respectively, are transmitted to the second and third inputs, respectively, to change the direction of movement. These signals at the inputs of the drive 2, provide the pyrometer 1 rocking or air

gate forward motion. In addition, the signal corresponding to the period of movement of the pyrometer from the output of the divider 6 is fed to the first input of the divider 8, the second input of which receives a signal from the setting unit 12 of the number of divisions corresponding to 2π2, and the output of which produces a signal

T

five

0

five

0 5 0 5

0

(formula (7)) tn - - time

plotting the ingot area. This signal from the output of the divider 8 is fed to the first input of the matching circuit 17, the second input of which receives a signal from timer 4, which calculates the current scan time of the next ingot section. While the current scan time has not reached the value of tQ — the specified scan time, the integrator 3, to the second input of which the pyrometer signal 1 is connected, integrates this signal. The output signal of the integrator 3 is fed to the first input of the divider 5, the second input of which receives the signal of the current scan time (and hence the integration) from timer 4, and the output of which forms the current average temperature of the section, which is fed to the fifth input of the multipoint recorder 9. When the current scan time reaches the specified scan time value, the coincidence circuit 17 generates a pulse arriving at the input of the element OR 18, and then along the leading edge of the pulse passing through the element NT OR 18, fed to the fourth input of the multipoint integrator 9, ends the registration of the current value by the fifth input, and the average temperature of the next segment is recorded. On the falling edge of this pulse, which passed the element OR 18, the timer 4 and the integrator 3 are zeroed out (on the first input). A similar procedure for the generation and processing of a pulse is carried out when the pyrometer reaches its extreme positions: one of the limit switches 15 or 16 produces a pulse arriving at the second and third, respectively, inputs of the OR 18 element, after which the leading edge of the pulse passed the OR 18 element is fixed average temperature

a multipoint recorder 9, and on the falling edge a timer and integrator 3 are zeroed.

In addition, the pulses from the limit switches 15 and 16 are fed to the third and second inputs of the multipoint recorder 9, respectively, to begin the preparation procedure for recording the temperature values of the new transverse band, as well as for calculating the values of the matrix of longitudinal gradients. At the first input of the multipoint recorder 9, a signal is received from the sensor 14 about the current and total length of the ingot, which is then used in recognizing the identified potentially defective sections of the ingot in front of the ingot cut unit.

As timer 4, an integrator may be used, the input of which is supplied with a constant reference voltage. As a multipoint recorder 9, a microprocessor complex can be used with the input elements of a number of pulsed signals (for example, KS 34.20), discrete initiative signals (for example, KS 34.03) and analog signals (for example, KS 31.07 with a KS 31.06 switch) In addition to the functions of a multipoint recorder, it can perform the procedure for maintaining an operational correction, analysis of matrices, temperature of longitudinal and transverse gradients, tracking potentially defective areas, displaying information (for example, her). Spectropyre 11-001 can be used as a pyrometer. As a sensor for the total length of the ingot, you can use a serial sensor with a number-pulse output, the measuring roller of which is set 1.5–5 m before the cutting line. The tachogenerators of alternating current, mounted on the shaft of the pulling stand electric motor, can be used as the casting speed sensor 13. The control of the extreme positions of the pyrometer can be carried out by contactless limit switches 15 and 16 of the type KVD-25. The element OR 18 is implemented on a chip. The remaining blocks can be made using an aggregate complex of electric control means in the microelectronic version, namely, as blocks 10-12 - manual setting controllers RZD-22; as blocks 3 and 4, a precision integration unit of the BPI-P type; as dividing blocks 5-8, BVO-P computing operations blocks; as a coincidence circuit 17, a conductive separation unit type BKRZ-P.

Example. Metal casting is carried out at a speed of 0.9 m / min 15 mm / s (at a maximum speed of 1.2 m / min 20 mm / s) in an ingot with a section of 400x300 mm2. To control the temperature, a spectropyre spectrometer pyrometer 11-001 is selected, measuring in the range of 600-1000 ° C, with a sighting factor of 1/50 and inertia t of 0.05 s. The pyrometer is mounted on a transverse gallery located downward from the secondary cooling hopper at a distance L 3 m above the ingot surface. Before casting, the operator enters from the setting unit 10 the width of the sight band Lp 60 mm, from setting unit 11 the value 2b / L 0.1 (3) characterizing the viewing angle of the pyrometer, from setting unit 12 - the double number of sections for splitting the ingot 2p2, determined by formulas (6) and (8):

 LjP 6

 6

LP

 15

(17) (T8)

In addition, it is predetermined by formulas (14) - (16) what is the relative error in determining the moments of passage of each section of the ingot during the swinging movement of the pyrometer compared to reciprocating:

Oi - arctg rb- 1.41262 °; (19) p p-b

sun l sinoЈ

cos | - about cos (- 1) with /.

 66.774532 mm;

(20)

Sun - 66 (6) mm

n2

I 0.16%

(21)

The error introduced by the swinging movement of the pyrometer, compared with its reciprocating movement is small, therefore, with the data

Specific conditions The swinging movement of the pyrometer is legitimate and justified.

Then, the main swing parameters are determined: the angular velocity Q and the moments of change in the direction of motion. The speed is determined by the formula (5) and its value is fed to the input of the drive 2:

3.8 OSS

(22)

 2U, Lp L

Moreover, a signal corresponding to 6 3.8 degrees / s is formed at the output of the third device divider 7 (Fig. 3). The moments of change of direction are determined by arriving at the inputs of the actuator 2 signals from the limit switches 15 and 16. By setting the main operating parameters in this way, the pyrometer is rotated, and the angular velocity of the pyrometer (and hence the linear spot rate) changes synchronously depending on on casting speed.

The swing pyrometer continuously scans the transverse strip of the ingot divided into n 6 sections, and the value of the temperature measured by it is continuously averaged by integrating the signal and dividing it by the current averaging time. To find and. recording the value of the temperature averaged over each of the sections, determine the specified averaging time (integration) equal to the scan time t0 of this section. According to formula (7):

2n.

period

T

LP

V

4 s

(23)

then

t about 2p 1

 Oh, (3) s,

(24)

the period T of the pyrometer oscillation is formed at the output of the second divider 6, and the averaging time (integration) t0 is formed at the output of the fourth divider 8. Then the integration end time is determined, for which the current integration time is counted and the current time is compared with the specified t0 O, (3) c. This is accomplished using timer 4 and coincidence circuit 17. When the current time coincides with the specified

register the last value of the continuously averaged temperature, and also restart timer 4 of the current averaging time and zero integrator 3 to calculate the average value of the next segment. The moment of the end of integration is also determined when the pyrometer reaches the extreme positions fixed by limit switches 15 and 16. This synchronizes the movement of the pyrometer and the measurement with averaging and recording temperature values, and also eliminates the possibility of an error obtained, for example, due to the error t .

as a result of error

source data, i

Upon reaching the extreme positions by the pyrometer, a multipoint recorder 9 (performed, for example, on the CTS LIUS-2) is prepared for recording the temperature values of the next transverse ingot strip corresponding to the new row of the temperature matrix, the number of rows of which is chosen

0

five

0

five

0

five

P.

- - s LP

(25)

where h is the thickness of the ingot, since half of the thickness of the ingot h / 2 (to the core) brings heat to the transverse strip with a width of Lp / 2.

This preparation of the recorder includes the following operations: recognition of scale points and correction of their values (by the second row of the matrix 9); determining longitudinal gradients 0 (| and b-tjj and transverse gradients 9 2 and ® 2zi) appropriately assigning the values of the fifth row of the matrix of values of the fourth c / row, the values of the fourth row — values of the third row, and so on, zeroing the first row of the matrix; the same procedure for matrices 0, and 62; the recognition of potentially defective areas and areas with uneven cooling associated with the misalignment of the nozzle plumes when they are partially or completely clogged. Based on the matrix Q with dimension 5 "6 ,,, the scale points and the corresponding temperature values are corrected. Let the given temperature profile be as follows: 950 C - in the middle of the strip with a decrease to 900 ° C - to the edge. Then the value is 13

02e 800 ° C is scaled by the point of scale, if all 912.9, 03g, 0g, bj, cn, bi, 014 is not lower than the specified temperature profile by an acceptable value. The temperature dip 02z, 924.0., For example, is identified as a potential defect, the temperature rise of the second column of matrix 0 is higher than the allowable value and / or the temperature drop of the third and fourth columns below the allowable value is identified as a distortion of the nozzle plugs as a result of their partial blockage. Anomalous gradient values (those that are more absolute than the maximum permissible) also identify a potentially defective area. Each such segment is attached to the total length of the ingot at the time of its detection 1OB1Cplus fixed length between the temperature control section and the cut unit (or the place of the ingot quality analysis before the cut) 1K, i.e. 1De (p 1K, which makes it possible to monitor the defective area and, if necessary, cut a segment of the ingot with a defect as unsuitable. In addition, the temperature and gradient values can be used to control the cooling mode of the ingot, such as in (4), the purpose of improving the quality of the cast ingot

The use of the invention allows to provide the necessary completeness and accuracy of information about the temperature of the surface of the ingot and its longitudinal and transverse gradients, which allows you to effectively adjust the cooling mode of the ingot in order to reduce defect formation and improve quality; filter the scale temperature values and, thus, do not unreasonably increase water consumption by zones, which leads to increased cracking and loss of waste; detect potentially defective areas of the ingot - tracking, which allows them to be cut out in time, if necessary, which leads to an increase in the quality of suitable blanks; to detect areas of uneven cooling of the ingot caused by torsion of the torch of the ZVO nozzles with their partial clogging, which allows to achieve quality improvement by replacing or cleaning them.

Thus, as a result of the invention, the ingot quality is improved.

Jq 15 20 25 30

and yield

14

In addition, the simplified method automatically Q 5 0 5 0

0 5 o

five

five

control of temperature, since only one pyrometer is used (instead of three or four) and it is not necessary to perform an ill-implemented operation of cleaning the surface of the ingot from scale.

Claims (2)

1. The method of automatic control of the temperature of the ingot surface during continuous casting, including sequential measurement of the temperature of sections of the ingot surface over its width with a pyrometer capable of moving, averaging the temperature values over each section, determining the gradient of the temperature of the ingot surface over its width, In contrast, in order to expand its functionality, it is continuously scanned with a pyrometer across the ingot without displacement along the technological axis of the machine, and the period and scanning speed are determined from the condition of measuring the temperature of the ingot surface area for any time interval not exceeding the ingot surface area During the same time interval, from the secondary cooling bin of the machine, the gradients of the temperature of the ingot surface are continuously determined by its width and length. 2. A device for automatic control of the ingot surface temperature, containing a pyrometer displacement drive, a pyrometer connected in series, an integrator, a timer, a divider and a multipoint recorder, the first timer output being connected to a divider, characterized in that, in order to extend the functionality, it further comprises pyrometer viewing angle setting device, pyrometer sighting width setting unit, numbering sites setting unit, ingot total length sensor, casting speed sensor, two limit switches, three dividers, a coincidence circuit, and an OR element, the output of the pyrometer sighting width setting unit is connected to the first input of the second divider, to the second input of which the output of the casting speed sensor is connected, and the output of the second divider is connected to the second input of the third divider, to the first input of which the output of the pyrometer viewing angle sensor is connected, and the output of the third divider is connected to the first input of the pyrometer movement drive, the second and third inputs of which are connected to the outputs of the first and second limit switches COOT-, respectively, the output of the second divider is connected to the first input of the fourth divider, to the second input of which the output of the setting unit for the number of divisions is connected, and the output of the fourth divider is connected to the first input of the matching circuit, to the second input where the second timer output is connected, and the output of the coincidence circuit is connected to the first input of the OR element, the second and third inputs of which are connected to the outputs of the first and second limit switches, respectively, and the output of the OR element is connected to the timer input, to the fourth input of the multipoint recorder and to the first the integrator input, the output of the total ingot length sensor is connected to the first multipoint recorder input; the second and first end outputs are connected to the second and third multipoint recorder inputs breakers, respectively. FIG. 2 Fm.z