JPH08159883A - Method of distinguishing normal / abnormality of mold thermocouple in continuous casting equipment and detection method of breakout using the same thermocouple - Google Patents

Abstract

(57) [Summary] [Purpose] Efficiency and accuracy improvement of thermocouple accuracy check,
Moreover, the breakout (B0) detection accuracy is improved. [Structure] A plurality of thermocouples 1 provided in the molds 11 to 14 are divided into groups corresponding to respective parts of the molds, and each of the thermocouple groups is measured with an electromotive force measuring device 2 via connectors 21 to 24. 1 connected to the mold and provided in the molds 11-14
While measuring the electromotive force by heating, the measured electromotive force is converted into a temperature value, and the thermoelectric group is determined based on the reference value determined in advance and the difference based on each thermocouple and the trend value of the thermocouple group. A method for distinguishing between normal and abnormal mold thermocouples in continuous casting equipment that distinguishes between normal and abnormal pairs. The variation value of the single thermocouple or the group, or all the thermocouples is ± 5 ° C., and the rising / falling temperature curve of the thermocouple is set within 3 ° C. in the temperature conversion value and then cast, and the upper thermocouple is measured. A method for detecting BO, wherein BO is defined when the lower thermocouple corresponding to the upper stage rises 5 ° C or more with respect to the peak value and then rises 5 ° C or more with respect to the measured peak value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining normality / abnormality of a thermocouple embedded in a mold used for continuous casting of steel sheets and a breakout detection method during casting.

[0002]

2. Description of the Related Art In continuous casting, the development of a normal solidified shell of molten steel in the mold is important for preventing surface defects and internal defects of the slab, and the formation of an unstable solidified shell is particularly rapid. Cause sexual breakout. The occurrence of this breakout causes serious accidents such as casting interruption and equipment damage, and also hinders the features such as high yield and high productivity inherent in continuous casting.

Further, this breakout has become more prominent as a result of the recent increasing number of products and higher grade products, as well as high-speed casting of these products due to high productivity.

Therefore, as a method of predicting or preventing these breakouts, a thermocouple is embedded in the mold and the temperature is detected.

A typical example of this is Japanese Patent Laid-Open No. 58-1.
There is one described in Japanese Patent No. 48064. This is to embed a plurality of thermocouples on the mold wall surface of the continuous casting equipment, and detect that the detected temperature of one of the thermocouples once rises and then falls from the detected average temperature. When a temperature change pattern of the detected temperature is subsequently detected by at least one other thermocouple adjacent to one thermocouple, it is predicted as a breakout occurrence. As another method, as described in JP-A-55-84259, among the four surfaces of the mold copper plate for continuous casting,
The temperature is detected at one or more places on each of the two or more faces, these temperatures are compared with each other, and the pre-phenomenon of the occurrence of the slab breakout is detected while using the temperature difference as an index. There is a way to adjust.

However, when the temperature rises and then falls below the detected average temperature of the thermocouples provided in the width direction of the mold and the temperature change of the adjoining thermocouples is observed at this time, or when there are two or more surfaces of the mold. Also in the case of detecting and comparing temperatures at one or more places, there are the following problems because only the temperature change in the width direction of the mold is detected.

First, the mold surface temperature does not always show a constant value even in a steady state.
The temperature often rises and falls repeatedly in the width direction of the inner surface of the mold or in the vertical direction due to fluctuations in the molten metal level. Especially, the thermocouple near the short side has a large tendency. The main causes of this are considered to be the air gap between the mold and the shell, non-uniformity of powder inflow, fluctuation of the molten metal level, and the like. Therefore, even if only the temperature change in the width direction of the inner surface of the mold or the temperature change in the vertical direction of the mold is detected, the number of false detections and non-detections increases, and the detection accuracy decreases significantly, which is difficult to put into practical use.

Furthermore, even during casting, which is estimated to be in a steady state, the above-mentioned temperature change may be large, or breakout may occur even in a region where the amount of temperature change is small. This means that the lower detection of the reference temperature reduces the number of non-detections, but the number of false detections increases. On the other hand, although the false detection can be reduced by increasing the temperature, the non-detection increases, both of which have problems in practical use.

Therefore, the present applicant first arranged a plurality of thermocouples in the width direction and the vertical direction in the mold, and any one of the upper stages of the thermocouple and any one adjacent to the thermocouple. The temperature of the thermocouple rises to 5 ° C. or more with respect to the peak value of each previous measurement, and the lower thermocouple of the upper equivalent portion is 10
Within 5 seconds, 5 against the peak value of the previous measurement of the lower thermocouple
A method of determining a time point at which the temperature rises by 0 ° C. or more as a breakout is disclosed (Japanese Patent Publication No. 5-75502).

[0010]

As described above, it is possible to judge a breakout at a time point when the peak value of the previous measurement is increased by 5 ° C. or more and the peak value of the lower measurement is increased by 5 ° C. or more. However, if the accuracy of the thermocouple cannot be maintained, this detection accuracy cannot be improved.
Further, in order to improve the accuracy, the temperature can be detected only by the temperature of the mold thermocouple in consideration of the tendency of the thermocouple alone and the whole.

Therefore, the problem to be solved by the present invention is to improve the efficiency and accuracy of the thermocouple accuracy check, and to improve the breakout detection accuracy.

[0012]

In order to solve the above-mentioned problems, the method for discriminating normality / abnormality of the mold thermocouple of the continuous casting equipment of the present invention is provided with a plurality of thermocouples provided in the mold, each of which is a part of the mold. The thermocouple group is connected to a measuring instrument for electromotive force through a connector, the thermocouple provided in the mold is heated to measure the electromotive force, and the measured electromotive force is measured. The electric power is converted into a temperature value, and the normality / abnormality of the thermocouple is determined based on the reference value obtained in advance and the determination based on the difference for each thermocouple and the tendency value of the thermocouple group.

Further, the breakout detecting method using the mold thermocouple of the continuous casting equipment of the present invention is such that a plurality of thermocouples provided in the mold are divided into groups corresponding to respective parts of the mold, Each of the thermocouple groups is connected to a measuring device for electromotive force via a connector, and the electromotive force is measured by heating the thermocouple provided in the mold, and the measured electromotive force is converted into a temperature value. The fluctuation value of a single thermocouple or a group or all thermocouples is ± 5 ° C, and the rising / falling temperature curve of the thermocouple is set within 3 ° C as a temperature conversion value, then cast, and the upper thermocouple measures. The temperature is increased by 5 ° C or more with respect to the peak value of, and then the breakout is the time when the lower thermocouple corresponding to the upper temperature is increased by 5 ° C or more with respect to the measured peak value.

[0014]

In the present invention, a plurality of thermocouples provided in the mold are divided into groups, for example, in units of mold pieces that are disassembled at the time of dismantling, and the thermocouples are connected to the main body of the measuring instrument by grouping them together. In the measuring instrument main body, individual characteristics of each thermocouple, average value determination, variation determination, and temperature rise / fall curve determination are performed to determine whether the thermocouple is normal or abnormal.

During normal temperature measurement, the temperature tendency of the molten steel in the mold construction is recognized in the 360 ° range, and the breakout detection corresponding to this tendency is performed.

[0016]

EXAMPLES The present invention will be described below with reference to examples. FIG. 1 is a perspective view showing an embodiment of the present invention.
Is a thermocouple embedded in each of the molds 11 to 14, 2 is a measuring device main body, and 21 to 24 are connectors.

In this embodiment, the slab size is 1600 m.
m-1 to m-1 having a thickness of 250 mm for continuous casting
In Fig. 4, 8 thermocouples were embedded in the slab width direction in the upper stage at a pitch of 200 mm, and 8 thermocouples were also embedded in the lower stage corresponding to the upper stage.
One on top and one on bottom was embedded in the short side. Replace the thermocouple with No. 1-4,
No. 5-8, No. 9-12, No. 13-16,
・ ・ Grouped into, and assembled into connectors with N = 4,
This was connected to the electromotive force measuring device main body 2. Steam having a temperature of 150 to 200 ° C. was uniformly blown onto the thermocouple having the above-mentioned configuration, the electromotive force was measured, the temperature was converted by the CPU incorporated in the measuring device main body 2, and further output under the temperature display condition.

As a result, no. 4 and No. Since the thermocouple of 13 was out of the standard value, the connection was repaired and this was corrected within the specifications and cast, and the thermocouple in the upper stage was 6 against the measured peak value.
The temperature was increased by ° C, and thereafter, the lower thermocouple corresponding to the upper temperature was 6 ° C or higher with respect to the measured peak value, which was recognized as a breakout. As a result of inspecting this slab after casting, it was confirmed that the breakout recognition and the situation of the actual slab were in agreement.

[0019]

As described above, according to the present invention, it is possible to reliably prevent breakout during continuous casting, avoid facility damage, avoid production hindrance, improve slab quality, and improve mold thermocouple. Faster detection can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a graph showing a temperature pattern of a thermocouple when a breakout occurs.

[Explanation of symbols]

1 thermocouple, 2 measuring device main body, 11-14 mold, 21
~ 24 connectors

Claims (2)

[Claims] 1. A plurality of thermocouples provided on a mold are divided into groups corresponding to respective parts of the mold, and each of the thermocouple groups is connected to an electromotive force measuring device through a connector, While measuring the electromotive force by heating the thermocouple provided in the mold, the measured electromotive force is converted into a temperature value, the determination based on the difference between each thermocouple and the reference value obtained in advance,
A method for discriminating normality / abnormality of a mold thermocouple of a continuous casting facility, which is characterized by discriminating normality / abnormality of a thermocouple from a tendency value of a thermocouple group. 2. A plurality of thermocouples provided on the mold are divided into groups corresponding to respective parts of the mold, and each of the thermocouple groups is connected to an electromotive force measuring device through a connector, While measuring the electromotive force by heating the thermocouple provided in the mold, the measured electromotive force is converted into a temperature value, and the fluctuation value of a single thermocouple or a group or all thermocouples is ± 5 ° C. After the temperature rising / falling temperature curve of the thermocouple is within 3 ° C in terms of temperature conversion, casting is performed, the thermocouple in the upper stage rises by 5 ° C or more with respect to the peak value of the measurement, and then the lower thermocouple corresponding to the upper stage A breakout detection method using a mold thermocouple of a continuous casting facility, which is characterized in that a breakout point is a point at which the temperature rises by 5 ° C or more with respect to a measured peak value.