JP3168234B2 - Method and apparatus for continuous temperature measurement of molten metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for continuously measuring the temperature of a molten metal in a tundish for ensuring the quality of a slab in a continuous casting process of the molten metal.

[0002]

2. Description of the Related Art In continuous casting, it is widely known that the casting temperature of a slab greatly affects quality and operation. For this reason, means for continuously measuring the temperature of the molten metal has been conventionally developed, and there is a thermocouple with an insulating glass in a continuous molten metal temperature measuring device disclosed in Japanese Utility Model Application No. 2-12201.

[0003]

Conventionally, a portion cast when a ladle for supplying molten metal to a tundish is replaced is called a seam, and is inferior in quality due to molten metal contamination such as oxidation and slag entrainment. The slab was demoted. At the time of ladle replacement, the supply of molten metal to the tundish is temporarily stopped, so that the level of molten metal in the tundish decreases and falls below the level of the temperature measuring probe. For example, as shown in FIG. 4, the temperature suddenly drops when the ladle is replaced, and the measured temperature does not represent the temperature of the molten metal. Such inability to measure temperature has not conventionally been a problem since the cast slab was demoted as described above. That is, even when the amount of the molten metal is reduced and the temperature cannot be measured continuously, there is no problem in guaranteeing the temperature.

[0004] However, the quality of the molten metal has been improved by improving the technology for preventing molten metal contamination when the ladle is replaced, so that the amount of molten metal is reduced, and the temperature is guaranteed when the temperature cannot be measured continuously. Has become an issue. That is, although the quality of the cast slab at the time of ladle replacement was improved, the cast slab at a position where continuous temperature measurement was not possible could not obtain a guaranteed temperature value and was regarded as defective.

[0005] It is an object of the present invention to perform temperature assurance over the entire casting range including a joint portion.

[0006]

According to the present invention, there is provided a method for continuously measuring the temperature of a molten metal in a tundish in continuous casting of a metal, wherein the amount of the molten metal in the tundish is reduced. The temperature measurement probe detects the exposure of the molten metal by the weight of the molten metal, and estimates the temperature of the molten metal while the probe is exposed from the molten metal. It is characterized in that the temperature measurement is started again by the continuous temperature measurement probe when immersed in the substrate.

[0007] The continuous temperature measuring device of the present invention is provided at a substantially constant height from the bottom of the tundish (1) for measuring the temperature of the molten metal in the tundish (1). A temperature measuring probe (2); means (5) for detecting the amount of molten metal in the tundish; a detection cycle (Tw) of the means (5) repeatedly with a predetermined period (Ts), While the amount of the molten metal is equal to or more than a predetermined value (TsL), a temperature reading value reading means (4) for reading the measured temperature (Tm) of the temperature measuring probe (2) and writing it in a memory means (temperature data memory). And the amount of the molten metal is a predetermined value (TsL)
A temperature estimating means (4) for estimating and calculating a current molten metal temperature (tm) by an extrapolation method based on a past temperature measurement value stored in the memory means. Symbols in parentheses indicate corresponding elements in the embodiment shown in the drawings and described later.

[0008]

[Action] By setting the predetermined value (TsL) to the lower limit of the amount of molten metal at which the temperature of the molten metal can be measured by the temperature measuring probe (2), the molten metal by the temperature measuring probe (2) can be obtained. While the temperature measurement is possible, the temperature measurement program
The measured temperature value of step (2) is written into the memory means. Then
When the amount of molten metal decreases and the molten metal temperature measurement by the temperature measuring probe (2) becomes impossible (measurement value is error), the temperature estimating means (4) uses the past temperature measurement value stored in the memory means. Based on the extrapolation method, the current molten metal temperature (tm) is estimated and calculated. As a result, the molten metal temperature value (estimated value) can be obtained even while the molten metal temperature measurement by the temperature measuring probe (2) is impossible. When the ladle is replaced (when the temperature cannot be measured by the probe), the change in the molten metal temperature until the replenishment of the molten metal is started is relatively gradual. Reliability is high.

When the replenishment of the molten metal is newly started, the temperature of the molten metal is generally high, so that the temperature of the molten metal rises, and the level of the molten metal in the tundish increases accordingly. Since the reliability of the extrapolated temperature estimate is low until the replenishment of the molten metal is started and the molten metal level in the tundish becomes possible to measure the temperature by the temperature measuring probe (2), for example, A continuous line A of the time-series temperature measurement values after the replenishment was started and the molten metal level in the tundish became possible to measure the temperature by the temperature measuring probe (2), and the time-series actual temperature measurement values before the replenishment started and Find the intersection of the time-series temperature estimation value with the continuous line B by extrapolation,
The temperature before this intersection is represented by the line B and the temperature after the intersection is represented by the line A, so that a relatively reliable temperature estimation value is obtained, the replenishment of the molten metal is started, and the level of the molten metal in the tundish is measured. The temperature can be obtained even before the temperature measurement by the probe (2) becomes possible, and a highly reliable temperature guarantee can be performed over the entire casting range including the joint.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0011]

1 shows an embodiment of the apparatus of the present invention, and FIG. 2 shows an embodiment of the method of the present invention. Reference numeral 1 shown in FIG. 1 denotes a tundish, which serves as an intermediate container for receiving molten steel from a ladle and injecting it into a mold. Reference numeral 2 denotes a continuous temperature measuring probe for measuring the temperature of the molten metal in the tundish. Also, in order to measure the temperature even with a small amount of molten metal,
It is necessary to measure the temperature at a position as close as possible to the bottom surface, but the temperature measurement position of the continuous temperature measurement probe is determined by the rule of thumb of the relationship between the measurement temperature and the temperature of the molten metal in the mold. It has been found that 8 to 3/4 is good. Reference numeral 3 denotes a device for converting the output of the temperature measuring probe into a temperature. Reference numeral 5 denotes a tundish weighing scale. Reference numeral 4 denotes a slab quality assurance data recording device.

FIG. 2 shows the contents of the continuous temperature measurement process of the slab quality assurance data recording device 4. The device 4 performs this processing at the sampling period Ts. First, when proceeding to the “continuous temperature measurement” process, a timer Ts for determining a sampling cycle Ts is set.
Is checked (Ts has elapsed since the previous sampling) (step 1; hereinafter, the word "step" is omitted in parentheses and only the numeral is written). If the time is over, the timer Ts is restarted to determine the next sampling timing (2), and the weight detection value Tw of the weight detector 5 is read (3). Then, it is checked whether the detected weight value Tw is less than the set value TSL (4).

The set value TsL is a lower limit value of the molten metal amount at which the reliability of the temperature measurement by the continuous temperature measuring probe 2 is ensured when the molten metal amount decreases during ladle replacement, and is based on the actual measurement environment. This is set in the slab quality assurance data recording device 4 in advance. The weight detection value Tw is equal to or greater than the set value TSL (the measurement data of the probe 2 is correct)
At times, the temperature measurement value Tm of the continuous temperature measurement probe 2 is read (5), and this is additionally displayed and printed on the displays 7 and 8 (6). Further, the temperature data inside the device 4 is stored.
The next oldest data is written to the address for writing the oldest data in the memory for storing group of data (temperature data memory),
For example, the next oldest data is written to the address where the next oldest data is written, and so on.
The address of the data is shifted (7), and the temperature value Tm read in step 5 is written to the opened address for writing the latest temperature data (8).

While the detected weight value Tw is equal to or larger than the set value TSL, the reading of the above-mentioned measured temperature value and the writing to the temperature data memory are repeated at a cycle of Ts.

The detected weight value Tw is less than the set value TSL (pro
When the temperature measurement value of the probe 2 becomes an error), the temperature data of the oldest temperature data write address in the temperature data memory is sequentially changed from the latest temperature data write address to the oldest temperature data write address.
A predetermined number n of data is read out at a predetermined sampling pitch, and a straight line (primary equation; quadratic equation may be a curve) representing a series of the read data (horizontal axis is time / vertical axis is temperature value) is calculated.
The temperature value Tm at the current point on this straight line is calculated (estimated) by extrapolation (11), and this is displayed on the displays 7 and 8.
Then, information indicating the estimated value is added, and additional display and printout are performed (6). Further, the address of the temperature data on the temperature data memory is shifted (7), and the temperature value Tm read in step 5 is estimated at the opened address where the latest temperature data is written. It is written together with the information representing the value (8). While the weight detection value Tw is less than the set value TSL, the calculation of the temperature (estimated value) and the writing to the temperature data memory are repeated at a cycle of Ts.

A host computer for controlling continuous casting.
The data instructs the slab quality assurance data recording device 4 to transfer data when necessary, and the device 4 transfers the data in the temperature data memory to the host computer in response to the command. The host computer assigns the transferred temperature data to the slab position, and if the temperature data is accompanied by information indicating the estimated value, the subsequent information indicating the estimated value is used. When temperature data without temperature addition (temperature measurement data after replacing the ladle) is obtained, a straight line A representing a series of the estimated temperature data and the actually measured temperature data before the temperature data, Temperature measurement data after replacing the pot
A straight line B representing a series of data is calculated, an intersection C of the two is calculated, and the estimated temperature data up to the intersection C is the straight line A,
The temperature estimation data after the intersection C is rewritten to those of the straight line A. In this way, the estimated temperature data is changed to be a tundish molten steel temperature guarantee value when the ladle is replaced (more precisely, a period in which Tw is less than the set value TSL).

[0017]

As shown in FIG. 3, if the present invention is used, the weight of the molten metal in the tundish is reduced, and the slab at a position where continuous temperature measurement cannot be performed is obtained by using the estimated value. I can guarantee it. The temperature of the molten metal in the pot after replacement is
Although the temperature is higher than that of the last injection before replacement, there is no problem because the temperature does not deviate from the temperature range required for quality assurance before and after replacement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the device of the present invention.

FIG. 2 is a slab quality assurance data recording device 4 shown in FIG.
Is a flowchart showing the contents of the continuous temperature measurement process.
It also shows the contents of one embodiment of the method of the present invention.

FIG. 3 shows the variation of the amount of molten metal in the tundish and FIG.
5 is a graph showing a relationship with a molten steel temperature estimation area by a slab quality assurance data recording device 4 shown in FIG.

FIG. 4 is a graph showing a relationship between a variation in the amount of molten metal in a tundish and a conventional temperature measurement value.

[Explanation of symbols]

1: Tundish 2: Continuous temperature measuring probe 3: Signal converter 4: Slab quality assurance data recorder 5: Tundish weight detector 6: Operation board 7: Display 8: Printer

Continued on the front page (72) Inventor Isamu Nara 1 Kimitsu, Kimitsu City Inside Nippon Steel Corporation Kimitsu Works (72) Inventor Yukio Moriya 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Steel Corporation In-house (56) References JP-A-48-22084 (JP, A) JP-A-64-110226 (JP, A) JP-A-2-165856 (JP, A) JP-A-2-200359 (JP, A) JP-A-2-303665 (JP, A) JP-A-4-274718 (JP, A) JP-A-3-104827 (JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) G01K 7/00 B22D 11/16

Claims (2)

(57) [Claims] 1. A method for continuously measuring the temperature of a molten metal in a tundish in continuous casting of metal, wherein the amount of the molten metal in the tundish is reduced and a continuous temperature measuring probe is exposed from the molten metal. That is detected by the weight of the molten metal, while the probe is exposed from the molten metal, the temperature of the molten metal is estimated, and then, when the continuous temperature measurement probe is immersed in the molten metal, the continuous A method for continuously measuring the temperature of a molten metal, which starts measuring the temperature with a temperature measuring probe. 2. A temperature measuring probe disposed at a substantially constant height from the bottom of the tundish for measuring a temperature of a molten metal in the continuous casting tundish; Means for detecting the amount of molten metal; repeatedly referring to the detection information of the means at a predetermined cycle, and reading the measured temperature of the temperature measuring probe and writing it into the memory means while the amount of molten metal is equal to or more than a predetermined value. Temperature value reading means; and temperature estimating means for estimating and calculating the current molten metal temperature by extrapolation based on past temperature measurement values in the memory means while the amount of molten metal is less than a predetermined value. Continuous temperature measuring device for molten metal.