JPS61226154A - Method for predicting breakout in continuous casting - Google Patents

Abstract

PURPOSE:To predict precisely breakout by excluding factors by a change of casting speed from the measured temp. values of the wall in a mold and making the judgement for prediction on the basis of the relative temp. determined from the ratio between the temp. at the prescribed measuring point and the entire measuring point. CONSTITUTION:The temp. Ti of the inside wall of the mold is measured by the plural temp. measuring elements provided in the mold of a continuous casting device. The factors by the change of the casting speed are excluded from the measured temp. Ti in accordance with the preliminarily determined relation between the temp. at each measuring point and casting speed. The ratio between the temp. T3 at the prescribed measuring point and the entire average temp. is determined as the relative temp. F(T3). The breakout is predicted when the relative temp. F(T3) deviates from the preset upper and lower limit values A, B. The precise prediction of the breakout is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for predicting breakout during continuous casting.

[Conventional technology]

Breakouts caused by insufficient heat removal from slabs reduce operating efficiency and can also cause accidents. Therefore, a method for reliably predicting this is strongly desired.

The conventional prediction method involves embedding temperature measuring elements consisting of thermocouples at close intervals in the width direction of the mold, and detecting the deviation of the mold temperature from the steady level to the lower or higher temperature side, respectively. The occurrence of breakout is predicted by the occurrence of surface cracks and the rupture of the solidified shell of the slab.

[Problem that the invention seeks to solve]

However, the temperature of the mold increases as the pouring speed increases, and decreases as the pouring speed decreases, so it is not reliable as a predictive method to judge only by vertical fluctuations (fluctuations) in the mold temperature.

Therefore, an object of the present invention is to provide a method that can accurately predict breakout.

[Means for solving problems]

In order to solve the above problems, the mold inner wall temperature at each temperature measurement point is measured by a plurality of temperature measurement elements provided in the mold of the continuous casting apparatus of the present invention, and the temperature at each temperature measurement point determined in advance is According to the relationship between the temperature and the casting speed, after removing the factor due to the change in the casting speed from the measured temperature, the ratio of the temperature at a predetermined measurement point to all measurement points is determined as a relative temperature, and this relative temperature is determined in advance. A breakout is predicted when the set upper and lower limits are exceeded.

[Effect]

As mentioned above, the measured temperature changes depending on the casting speed.

Therefore, after removing the factors caused by changes in pouring speed, we introduced the concept of "relative temperature" and used this as a criterion for prediction. Therefore, it is possible to accurately predict breakout without being affected by changes in casting speed.

[Specific examples of the invention]

The present invention will be further explained below.

In the present invention, as shown in FIG. 2, for example, 18
A large number of temperature measuring elements 3t consisting of thermocouples passed through guide tubes 2 are embedded at a distance of 5 m. 4 is molten steel, and 5 is a frame.

On the other hand, FIG. 3 shows the relationship between the temperature Ti obtained from the temperature measuring element 3 at a position p250 below the upper end of the molded copper plate and the casting speed Vi.

Therefore, equation (1) holds true.

Ti=a iVi+b i-” (1) However, i:
Number of each temperature measuring element Ti: Temperature of the copper plate (inner wall of the mold) vc: Casting speed al, J: Constant of each temperature measuring element determined by the mold As a result, the average temperature of each temperature measuring element is determined by the number of temperature measuring elements n
According to the inquiry, it can be expressed by the following formula.

On the other hand, as shown in FIG. 4, even if the position of the temperature measuring element with respect to the mold changes, the degree of temperature rise due to the casting speed does not change.

Therefore, the mounting of the temperature measuring element is caused by the change in position b.
By excluding X and finding the relative temperature F('rx) between the temperature at the temperature measuring element X and the total average temperature, the influence of the casting speed can be eliminated.

Therefore, using this, the relative temperature F at each point of the mold is
By monitoring (T), breakouts can be accurately predicted. Specifically, the reference value "('rx)" is determined using the relationship in equation (2) above.

Next, in the same way, the raw temperature data Ti is substituted into the above equation (2), room temperature monitoring is performed, and the relative temperature F (Tx) is equal to the reference value FI.
<T engineering) A breakout alarm is output when the predetermined upper and lower limits are exceeded. The upper limit value and lower limit value may be determined from the transition of F (T work) at the time of breakout in actual operation.

In the above description, the case where the temperature measuring point is provided in the vertical direction of the inner wall of the mold has been described, but it goes without saying that the same effect can be achieved by placing the temperature measuring point in a horizontal direction, an oblique direction, or a combination thereof.

〔Example〕

Figure 1 shows changes in relative temperature F('rx) and breakout prediction alarm output according to an embodiment of the present invention. This is the third temperature measuring element temperature. Also, in the same figure, line (A) t
i Reference value F” (T),! (B) C upper limit value, line (C
') C lower limit value, line (B) is relative temperature F(T3), line (
g) was carried out by setting the raw temperature measuring element temperature T5 to 1, and in this example, the upper and lower limits were set to ±30% of the reference value F'' (Ts).

F(T3) (7) for approximately 450 seconds after the start of casting.
The value is within the upper and lower limits, but it drops below the lower limit just before the breakout occurs, and a breakout occurs immediately after the alarm is output. As is clear from this figure, according to the present invention, by outputting an alarm when the relative temperature F(Tx) exceeds the predetermined upper and lower limit range,
Breakouts can be predicted accurately.

〔Effect of the invention〕

In summary, according to the present invention, it is possible to accurately predict breakout without being affected by the casting speed. Also, as a method of prediction, there is no need to use special means,
It's also practical.

[Brief explanation of the drawing]

Fig. 1 is a time course diagram showing the operation carried out under the prediction method according to the method of the present invention, Fig. 2 is a sectional view of an example of mounting the temperature measuring element, and Fig. 3
The figure is a correlation diagram between the casting speed and the thermocouple (mold inner wall) temperature, and FIG. 4 is a relationship diagram showing the degree of rise in mold temperature depending on the casting speed due to changes in mold position. 1...Mold, 3...Temperature measuring element. Figure 3 (Sugome Inoki Island) Figure 4

Claims (1)

[Claims] (1) The inner wall temperature of the mold at each temperature measurement point is measured by multiple temperature measurement elements installed in the mold of the continuous casting device, and based on the relationship between the temperature at each temperature measurement point and the casting speed determined in advance, After removing the factor caused by the change in pouring speed from the measured temperature, the ratio of the temperature at a predetermined measurement point to all measurement points is determined as a relative temperature, and this relative temperature is outside the preset upper and lower limits. A method for predicting a breakout in continuous casting, characterized in predicting a breakout when the breakout occurs.