JPS6021812B2 - Method and device for measuring lubrication status between mold and slab in continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring the lubrication performance between a mold and a rust piece in continuous casting of molten metal.

Generally, continuous casting of molten metal is carried out through a tundish 1 and a mold 2 having a predetermined cross-sectional shape, as shown in FIG.
Molten metal 4 is injected into the inside and continuously pulled out as coins 3 from below.

In the process of pulling out the coins 3 from the mold 2, as shown in FIGS. 2 and 3, the coins in the mold 2 are vibrated by the mold vibrating device 6 at a constant cycle that matches the operating conditions. While the powder 5 on the mold 3 is melted by the heat of the molten metal 4, the molten powder flows between the mold 2 and the mirror piece 3 through mold vibration, and serves as a lubricant. Depending on the lubrication state between the mold 2 and the coin piece 3, scratches or cracks may occur on the surface of the mirror piece 3, or breakout (hereinafter referred to as BO) may occur.

However, there is no effective means for measuring and evaluating the powder lubrication performance between the mold 2 and the twill 3, or for measuring information on the occurrence of surface scratches or preventing them. The reality is that it is not possible to prevent BO from occurring. MLL is a method for measuring these lubrication performance.
- There is a measurement method proposed by TEKTOR (Belgium Patent No. 869032).

This measurement method detects the vibration of the mold and uses the vibration to determine changes in the friction between the mold and the coin. However, in actual continuous casting, operating conditions that incorporate time factors change. That is, the mold vibration frequency is changed in accordance with the drawing speed level of the fin piece. Therefore, even if the detected value is compared with a predetermined reference signal, it is not possible to accurately detect changes in the frictional state between the key piece and the mold. The present invention aims to accurately measure the lubrication state in view of these circumstances. As a result of various studies, the present invention considers the mold vibration device as a system, obtains at least part of the frequency transfer function online, selects a specific frequency (one or more), and calculates the magnitude and/or phase of the component. Obtain continuously or intermittently, display and record, and depending on the state of change,
To accurately measure the lubrication state between the mold 2 and the scales 3. This method also applies to the vibration of the mold when the mold vibration device changes, when the lubrication state between the mold 2 and the sickle piece 3 changes, and when the lubrication state between the mold 2 and the mirror piece 3 changes. The feature is that at least a part of the transfer function indicating the state of the device is determined.

In this invention, the vibration of the vibration drive source of the mold vibration device is used as input, and the vibration of the mold is used as output, and the lubrication performance is measured based on their mutual relationship (mid-vibration, phase). It is.

The conditions for the vibration region required for measurement are that both the input side and the output side always have that vibration region, and that the vibration region is highly sensitive for measuring lubrication performance. The vibration regions that particularly satisfy these conditions are the forced vibration region of mold vibration and the natural vibration region of the mold vibration device. The present invention will be described in detail below with reference to the drawings.

Figure 2 shows a general mold vibration device 6 for continuous casting equipment.
It is composed of a mold drive section 6a and a vibration transmission section 6b. The mold drive section 6a is composed of a motor, a speed reducer, and a crank mechanism within the speed reducer, and these mechanisms convert rotational motion into vertical motion, causing the mold 2 to vibrate through the vibration transmission section 6b. In the present invention, the mold vibration device is considered as one system, and, for example, the movement of the mold drive unit 6a is input x(t
) "The frequency transfer function is determined using the apparatus configuration shown in FIG. 4, with the vibration transmission section 6b to the mold 2 as the transmission system and the vibration of the mold 2 as the output y(t).

FIG. 4 shows the configuration of an embodiment of the present invention, in which a vibration detector 7 for input x(t) measures the displacement of the crank mechanism of the mold drive section 6a, amplifies it with an amplifier 9, and amplifies it with an amplifier 9. 11 is entered. The vibration detector 8 with the output y(t) is
The vibration of the mold 2 is detected, amplified by an amplifier 10, and input to a signal processor 11. The signal processor 11 performs various calculations on these two signals input to the signal processor 11, calculates a transfer function or cross spectrum, and calculates a preset frequency gain (G
(f)) and phase (of (f)) are continuously displayed on recording device 1
2 is output. Changes in gain G(f) and phase (f) indicate changes in the lubrication state between mold 2 and coin 3. Here, a method for measuring the frictional state between the mold and the coin will be specifically explained.

The relationship between input x(t) and output y(t) shown in FIG.
It is as follows.

In other words, the relationship between the autocorrelation function 0matsu (↑) of the input x(t) and the spectral density function Gx(f) is
1/T)′sa×(t)●X(t+7)dt.・・・--
‐‐‐{110×(f) = (1/T) Noyoshi de Matsu (7)・e "WTd↑.....
...'2} Also, the correlation function between input x (t) and output y (t) ◇ Square (7) and mutual spectral density function Gxy (f
) is gu (7) = (1/T) Nokichi X (t) ●y (t + D) dt.・・・．
・・・． ...'3-G square (f) = (1/T)'; J fence (7)・e-jW7d pieces.・・・．
・・・． ...[4'Here, G increase (f) is G double (f) ni IGxy (f) le-j0xy[? ).・
・．．・・・． ...'51 cross spectrum has amplitude and phase information.

On the other hand, the frequency transfer function (f) is IC (f) le-j? Xym = I day (f) lei?・Gx(f)…. ...'6
}IG fence (f) l = I day (f) l・Gx (f)
．． ．． ．． ．． ．． ．． ...{7'◇guy(f)=? (f)
……■．・．． I day (f) l: IG square (f) l
/Gx(f)/Gx(f). ...{9} When the mold vibration device is replaced with a spring model, the result is as shown in Fig. 8.

In the spring system model shown in Fig. 8, the transfer function day (f)
is (f)=y(t)/x(t)
C0R)/(k-M2) ......00G(f)={
ak/i (k1M) 2 10 (C0R) 2 not}……(
11) ○(f) Nine nl (C + R) / (k - M 2) .・・・． ...(12) Here, 2 is a symbol indicating the angle, and M: Mold weight K: 'Imitation constant C: Viscosity coefficient R: Friction a: Amplitude of mold vibration: Angular velocity in mold vibration. =2mf, f: vibration frequency 7 = t T: vibration period, K, M, and C are known.

Therefore, equations (11) and (12) are functions of the friction R between the mold and the coin.

The behavior of the friction R between the mold and the coin piece indicates the lubrication between the mold and the coin piece, so the above-mentioned Gx(f
) and ma (f), the lubrication state can be determined by measuring the friction state between the mold and the fin piece.

If the required frequency f is only a single frequency, for example, if it is only the fundamental frequency of mold vibration, then the gain and phase for it can be easily found. Ru. This will be explained with reference to FIG. The input x(t) and the output y(t) are input to amplifiers 13 and 14, amplified, and passed through filters 15 and 14.
Enter 16. Required frequency components are extracted by filters 15 and 16 and input to a gain measuring device 17 and a phase detector 18. The relationship and degree of the relationship between the input x(t) and the output y(t) are determined by the gain measuring device 17, and are continuously recorded by the recording device 19. The phase detector 18 inputs x(t
) and the output y(t), and record it continuously using the recording device pupil 20. It is also displayed on the display device 21.
Although vibration measurement using a displacement meter was shown as an example of implementation as vibration input for the drive source of the mold vibration device, vibration measurement is
A speedometer, accelerometer, etc. may also be used. Further, as for the vibration of the drive source of the mold vibration device, the rotary motion of the motor is decelerated by a speed reducer and converted into vertical motion by a crank mechanism or a biased D cam, and this vertical motion becomes the vibration of the drive source.

Therefore, the current signal or voltage signal of the motor may be used as the vibration input of the drive source. Figures 6a to 6a show the data measured in the continuous casting equipment of the example steel factory.
Shown in Figure 7b.

These graphs show the lubrication performance determined by the transfer function. Figure 6a shows that the lubrication performance is in good condition.
Figure b shows the deterioration of lubrication performance. Figures 7a and 7b show the phase change of a certain frequency, Figure 7a shows information that the lubrication performance is getting worse, and Figure 7b shows that surface scratches have occurred. It shows something. Sensing end 1 used: input x(t), eddy current displacement meter 2: output y(t), accelerometer As described above, in the present invention, the mold vibration device is considered as a system, and input x(t) and output Find the mutual relationship (transfer function, etc.) of y(t) and find the gain G(f) at an appropriate frequency.
The phase (f) of It is possible to obtain lubrication performance without being affected by changes.

'2' In order to obtain the frequency gain and phase for mold vibration, the lubrication information between the mold and the coin is extremely sensitive.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an overview of the mold section of continuous casting equipment, Fig. 2 is a side view showing an example of a mold vibration device, and Fig. 3 is a cross-sectional view showing the state of coins in the mold. 4 and 5 are block diagrams showing the measuring device of the present invention, and FIGS. 6a, 6b, 7a, and 7b are graphs showing some of the measurement results. FIG. 8 is an explanatory diagram showing the mold vibration device as a spring system model. 1: Yusodishu, 2: Mold, 3: Money piece, 4
: Molten metal, 5: Powder, 6: Mold vibration device, 6
a: Mold drive unit, 6b: Mold transmission mechanism, 7, 8
: Vibration detector, 9, 10: Amplifier, 11: Signal processing dead end, 12: Display and recording equipment, 13, 14: Amplifier, 15, 1
6: filter, 17: gain measuring device, 18: phase detector, 19, 20: recording device, 21: display device. Fig. 1 Fig. 2 Fig. 3 Fig. 3 Sabamu Fig. 5 Fig. 6a Fig. 6b Fig. 8 Fig. Rudder diagram Rudder

Claims (1)

[Scope of Claims] 1. When continuously casting molten metal while vibrating a mold, a change in either or both of the phase and amplitude between the vibration input from the vibration drive device and the vibration of the mold. A method for measuring the lubrication state between a mold and a slab in continuous casting, the method comprising measuring the friction state between the mold and the slab. 2. A vibration detector for detecting vibrations of the vibration drive source of a continuous casting mold vibrator that transmits vibrations from the vibration drive source to the mold via a spring to vibrate the mold;
an amplifier for amplifying a vibration detection signal detected by the vibration detector; a mold vibration detector for detecting vibration of the mold; and a mold vibration detection signal detected by the mold vibration detector. an amplifier; a signal processing device into which the amplified vibration signal of the vibration drive source and the amplified mold vibration signal are input; and a signal processing device that calculates a vibration transfer function from the vibration drive source to the mold; A lubrication state measuring device between a mold and a slab in continuous casting, comprising a display and recording device that displays and records changes in a calculated vibration transfer function.