KR20030037339A - Monitoring apparatus of continuous casting mold - Google Patents

Abstract

PURPOSE: A monitoring apparatus of continuous casting mold is provided to realtime grasp initial solidification behavior in the mold and mold vibration behavior during casting according to friction behavior between mold and solidified shell varied depending on casting conditions and facility state. CONSTITUTION: In an apparatus for monitoring behavior of mold for continuous billet caster, the monitoring apparatus of continuous casting mold comprises a plurality of thermocouples(201) installed on the mold to measure temperature of the mold; three-axis vibration sensors(202) installed on cooling water jacket for cooling the mold to measure three-dimensional behavior of the mold; a current converter(208) installed at a power source of motor for vibrating the mold to measure change of current values of the motor; signal conversion means(204,210,213) and signal transmission means(205,214) for transmitting the digital signals to the online monitoring system after converting signals of the thermocouples, three-axis vibration sensors and current converter and signals for casting conditions of the mold into digital signals; and an online monitoring system(200) for monitoring behavior of the mold by displaying the digital signals for temperature, vibration, current and casting conditions transmitted through the signal conversion means(204,210,213) and signal transmission means(205,214) on a monitor.

Description

Monitoring apparatus of continuous casting mold

The present invention relates to an apparatus for monitoring the initial solidification behavior in a mold in continuous casting of billet, and in particular, the initial solidification behavior in a mold according to the friction behavior between the mold and the solidification cell, which changes according to casting conditions and equipment conditions. The present invention relates to a continuous casting mold monitoring device capable of real-time grasping of mold vibration behavior during casting.

In continuous billet casting, the initial solidification in the mold determines the overall quality and the stability of the operation. Particularly, if solidification occurs unevenly due to insecure water surface, poor mold lubrication, inadequate primary cooling condition, inflow of powder unevenness, mold vibration unevenness, deformation of the mold, cracks on the billet surface or severe breakout. (breakout) occurs. Therefore, in order to stabilize the quality and operation, it is necessary to stabilize the initial coagulation. For this purpose, studies to stabilize the initial coagulation as well as to monitor the initial coagulation behavior have been conducted by many researchers.

Conventionally, in order to identify the initial solidification behavior in a mold during billet casting, a thermocouple is installed in the mold to measure the temperature of the mold intermittently and temporarily when necessary, and then compare the measured data with the casting speed and the primary coolant temperature. The analysis was used as basic data for heat transfer and non-uniform coagulation in the mold.

However, only the data such as heat transfer that can be obtained by intermittent temperature measurement of a simple mold, the frictional force between the mold and the cast slab caused by deformation of the mold during casting, change in shrinkage caused by solidification according to the cast steel type, and irregular inflow of powder Due to the variation of the mold and the non-uniformity of the mold vibration, it is impossible to quantitatively analyze the cause of quality deterioration over a long period of time, and also it is difficult for the operators to immediately deal with problems in real time during operation. In particular, during continuous casting of the billet, the mold vibration changes sensitively to mechanical defects of the mold vibrating device, and the vibration in the horizontal direction as well as the vertical vibration occurs simultaneously. There is a need for a technique that monitors the mold vibration behavior and can measure the temperature of the mold in order to understand its function.

1 schematically shows an apparatus for displaying a vibration load during vibration of the continuous casting apparatus described in Japanese Laid-Open Patent Publication No. 59-209467. As shown in FIG. 1, the technique installs each load cell 101, 102, 103, 104 on a vibrator 106 installed on four axes of the mold table 107 supporting the mold 105. In addition, by analyzing the signals obtained from each sensor and the difference, it is possible to reduce the occurrence of surface defects of the cast and to extend the service life of the mold.

However, the technique used the results obtained by analyzing the signals generated in each of the four axes to monitor the action of the mold vibrating mechanism, which has the disadvantage of being applicable only to a general player with a mold vibrating table. In addition, the technique has a disadvantage that it is easy to use only when measuring the vibration behavior of the mold in the vertical direction. However, the billet player does not have a mold vibrating table operating in four axes, and only supports the mold on one of the four surfaces and vibrates the mold by using a motor. Therefore, the technique of using the load cell as described above to identify the mold vibration behavior of the billet is not applicable.

In addition, the billet mold has not only vertical vibration but also horizontal vibration due to casting conditions due to deformation of the mold during casting, a change in shrinkage amount generated during solidification according to the cast steel type, and irregular inflow of powder. Therefore, in the case of billet molds, a monitoring apparatus capable of identifying the mold vibration behavior of three axes (x, y, z axes) is necessary.

Korean Utility Model Registration Application No. 89-20631 describes a system that can measure the vibration behavior of a mold offline and in real time during casting by using a vibration acceleration sensor. And surveillance system). This technology is a stand-alone system capable of measuring only the vibration of a mold. The linkage analysis with cast quality, that is, the effect of mold vibration on initial solidification for each time series during casting and the quality of final billet There is an impossible disadvantage. In addition, this technique has a disadvantage in that it is very difficult to find in real time the correlation between casting conditions, that is, casting speed, primary cooling water amount, casting speed change, and mold vibration.

Accordingly, the present invention has been made in order to solve the problems of the prior art as described above, and receives the casting condition signal during continuous billet casting, vertical vibration and horizontal direction of the mold by using a three-axis vibration sensor and a current transducer By identifying the vibration behavior in real time, it provides a continuous casting mold monitoring value that can monitor the physical frictional behavior between the mold and the cast and analyze the factors that may affect the initial solidification in the mold due to heat transfer change. The purpose is.

1 is a schematic diagram of a prior art device for displaying the vibration load of a mold,

Figure 2 is a schematic diagram schematically showing the overall configuration of the continuous casting mold monitoring apparatus according to an embodiment of the present invention associated with a continuous casting machine,

3 is a block diagram of the continuous casting mold monitoring apparatus shown in FIG.

Figure 4 is a detailed view showing the position of each of the thermocouple installed to measure the temperature of the mold in the continuous casting mold monitoring device shown in Figure 2,

5A and 5B are sectional views and a front view showing the attachment position of the three-axis vibration sensor of the continuous casting mold monitoring device shown in FIG.

FIG. 6 is a cross-sectional view of a mold having a thermocouple installed in the mold monitoring apparatus shown in FIG. 2 and a coolant jacket having a three-axis vibration sensor attached thereto;

7 is a view showing a center screen of the online monitoring device of the continuous casting mold monitoring device shown in FIG.

FIG. 8 is a view showing a monitoring screen displayed on the online monitoring device of the continuous casting mold monitoring device shown in FIG.

9 is a view showing a basic screen for monitoring the casting signal and the mold vibration behavior through the online monitoring device of the continuous casting mold monitoring device shown in Figure 2 during billet casting,

10 is a view showing the change behavior of the current signal,

FIG. 11 is a graph illustrating the analysis of the quality of the cast steel and the data obtained through the mold sensing market value of the present invention illustrated in FIG. 2.

♠ Explanation of symbols on the main parts of the drawing ♠

200: mold monitoring device 201: thermocouple

202: 3-axis vibration sensor 203: connector terminal box

204, 210, 213: signal converter 205, 214: signal transmitter

206: online monitoring device 207: RS receiving card

208: current converter 209, 212: isolator

211: casting signal extracting device 215: mold

216 coolant jacket 217 signal line

218: Connector

The continuous casting mold monitoring device of the present invention for achieving the above object is provided in a plurality of thermocouples installed on the mold to measure the temperature of the mold, and installed in a coolant jacket for cooling the mold to control the three-dimensional behavior of the mold. A three-axis vibration sensor to measure, a current converter installed in a power source of the motor vibrating the mold, and measuring a change in the current value of the motor, signals of the thermocouple, three-axis vibration sensor and current converter, and casting conditions of the mold The signal conversion transmission means for converting a signal into a digital signal and then transmitting the signal to an on-line monitoring device, and displaying the digital signal of temperature, vibration, current, and casting conditions transmitted through the signal conversion transmission means on a monitor to display the behavior of the mold. It characterized in that it comprises an online monitoring device for monitoring.

In the following, with reference to the accompanying drawings a preferred embodiment of the continuous casting mold monitoring apparatus according to the present invention will be described in detail.

The mold monitoring apparatus of the present invention monitors mold temperature and casting conditions in real time during casting to monitor factors that may affect the initial solidification behavior started from the mold during continuous casting of the billet, and the vibration behavior of the mold according to the casting conditions. In order to analyze this, a three-axis vibration sensor and a current transducer for measuring the current value of the motor for mold vibration are used.

Figure 2 is a schematic diagram showing the overall configuration of the continuous casting mold monitoring apparatus according to an embodiment of the present invention associated with a continuous casting machine, Figure 3 is a block diagram of the continuous casting mold monitoring apparatus shown in FIG.

As shown in FIG. 2, a typical continuous casting machine is manufactured by casting molten steel 108 at a high temperature through a tundish 109 and starting to solidify in the mold 110. The present invention is to monitor the mold in the continuous casting machine as described above.

As shown in Figures 2 and 3, the mold monitoring apparatus 200 of the present invention includes a thermocouple 201 for measuring the temperature of the mold, and a triaxial vibration sensor 202 for measuring the behavior of the mold. The thermocouple 201 and the triaxial vibration sensor 202 have their signal lines connected to a connector terminal box 203 provided outside the mold for ease of assembly. In addition, the signal lines of the thermocouple 201 and the 3-axis vibration sensor 202 are converted to a digital signal that can be used in a computer that is an online monitoring device using different analog signals in common through the connector terminal box 203. The first signal converter 204 is connected. That is, the volt signal, which is a signal unique to the thermocouple 201 and the triaxial vibration sensor 202, is converted into a digital signal while passing through the first signal converter 204. The converted digital signal is transmitted to the RS-485 receiving card 207 installed in the online monitoring device 206 through the first signal transmitter 205 in a RS-485 manner.

In addition, the mold monitoring apparatus 200 of the present invention includes a current converter 208 is installed in the power supply of the motor for vibrating the mold to measure the change in the current value of the motor. The current signal drawn from the current converter 208 is transmitted to the first signal transmitter 205 through the second signal converter 210 via the first isolator 209 which is a reverse signal blocking device.

As such, the mold monitoring apparatus 200 of the present invention measures the change in the current value according to the mold vibration through the current converter 208 installed in the power source of the motor. The measured current value of the motor is different depending on the change of friction between the mold and the solidification cell. That is, in the case of casting conditions or steel grades in which the friction between the solidification cells is large, a large load is generated in the motor, so that the current value increases, and when the friction is small, the current value decreases. This current value is repeatedly raised and lowered according to the mold vibration.

In general, the current value is expected to be a typical sine waveform when rising and falling, but irregular waveforms are generated depending on the friction conditions and mold vibration conditions of the mold. Thus, the present invention is to determine the vibration behavior of the mold by installing the three-axis vibration sensor 202 and the current transducer 208 as described above to measure the vibration of the mold more precisely. That is, the current converter 208 is installed in the power supply of the mold vibration motor located in the electric room of the billet factory.

The present invention also includes a casting signal extraction box 211 that collects casting condition signals such as casting speed, hot water fluctuation, opening of a sliding gate, and primary cooling water amount. That is, each volt signal drawn out through the foundry signal extraction box 211 is online through the second isolator 212, the third signal converter 213 and the second signal transmitter 214 via RS-485 method. The RS-485 receiving card 207 of the monitoring device 206 is transmitted.

The present invention enables to measure the mold temperature and the behavior between the mold and the solidification cell according to the casting conditions and steel grades by continuously monitoring the signal, mold temperature and casting conditions for the mold vibration during casting through the above components.

Figure 4 is a detailed view showing the position of each of the thermocouple installed to measure the temperature of the mold in the continuous casting mold monitoring apparatus shown in FIG. As shown in FIG. 4, the thermocouple 201 is provided with a groove formed in the mold and installed therein, including 32 on the right side of the mold, 24 on the left side, 4 on the top side, and 4 on the bottom side. do. This thermocouple 201 is a T-type thermocouple capable of precisely measuring temperature in a low temperature region of 400 ° C or lower.

These thermocouples 201 are installed at intervals of 50 mm in the casting direction to measure the temperature gradient in the casting direction, and are respectively installed on both sides separated by about 30 mm from the center of the width portion and the corner of the slab in the width direction, and the temperature in the width direction. The change is measured. In particular, the thermocouple 201 is installed at intervals of 20 mm at positions 150 and 170 mm, which are initial solidification portions in the mold, to measure the temperature in detail according to the change in the water surface. In addition, in order to compare the temperature change of the hot water surface part with each other, the thermocouples 201 are installed at the positions of 170 and 220 mm on the upper and lower surfaces, respectively, to measure the temperature of the mold.

5A and 5B are cross-sectional views and front views showing the attachment position of the three-axis vibration sensor of the continuous casting mold monitoring apparatus shown in FIG. The triaxial vibration sensor 202 shown in FIGS. 5A and 5B measures vibration behavior of the mold, and is installed outside the coolant jacket 216 that supports the mold 215 of FIG. 6 and serves as a coolant passage. do. Since the installation of the 3-axis vibration sensor 202 in the coolant jacket 216 is not only easy to install, but the mold of the billet is wasteful after a certain number of times of use, the coolant jacket 216 can be continuously used. This is because the vibration behavior of the mold for a long time is easy to measure. Further, the more important reason is that the deformation of the coolant jacket 216 accompanying the deformation of the mold due to the pressure of the coolant during the casting and the rise of the temperature of the coolant can be accurately measured.

The mold vibration should be vibrated only in the vertical direction in the casting direction, that is, in the y direction of FIG. However, unlike the slab casting, the actual billet casting vibrates the mold in a manner that supports one side rather than the four-sided support method, so that horizontal vibrations are caused by deformation of the mold and a change in frictional force due to the steel type. As it occurs, it should be able to measure the vibrations in the x and z directions as well as the vibrations in the y direction as shown in FIG. 5. Thus, in the present invention, the three-axis vibration sensor 202 is used.

FIG. 6 is a cross-sectional view of a mold having a thermocouple installed in the mold monitoring apparatus shown in FIG. 2 and a coolant jacket equipped with a 3-axis vibration sensor. The signal line 217 of the thermocouple 201 and the 3-axis vibration sensor 202 shown in FIG. 6 is drawn out of the mold along the upper cover of the coolant jacket 216 so that there is no leakage of coolant and interference of the facility. In addition, a connector 218 for convenience of installation due to replacement of the mold is provided at the tip portion of the signal line 217, and the mold can be easily replaced by using the connector 218. FIG.

FIG. 7 is a diagram illustrating a center screen of the online monitoring device of the continuous casting mold monitoring device shown in FIG. 2. As shown in FIG. 7, the on-line monitoring device 206 of the present invention visually observes the temperature of each thermocouple 201 directly through the screen according to the position of the mold during casting, and not only the casting signal but also the 3-axis vibration sensor. The signal 202 and the current signal of the motor can be monitored by digital numbers, respectively.

FIG. 8 is a diagram illustrating a monitoring screen displayed on the online monitoring device of the continuous casting mold monitoring device shown in FIG. 2. As can be seen in Figure 8, the present invention can monitor various casting signals, thermocouple signals, signals of the sensor by time series through the respective monitoring screen. In addition, the on-line monitoring device 206 monitors the casting signal and automatically stores data so that analysis of the casting conditions such as casting temperature, casting speed, and mold vibration etc. can be performed after completion of casting. In other words, even in the case of two steel grades with similar actual casting conditions, the temperature and vibration behavior of the mold vary depending on the installation conditions. In this case, the frequency analysis of the vibration measurement data and the phase difference of the x, y, and z axes are analyzed. The mold vibration behavior can be identified.

In addition, the present invention was able to measure the change in the current value during the up and down movement of the mold according to the mold frequency that changes according to the casting speed, and this data can be displayed on the screen in real time.

9 is a view showing a basic screen for monitoring the casting signal and the mold vibration behavior through the online monitoring device of the continuous casting mold monitoring device shown in Figure 2 during billet casting. As can be seen in Figure 9, the present invention is to monitor the casting conditions and the mold vibration measured during the actual casting, by monitoring the casting conditions at the upper end of the screen, and to monitor the mold vibration at the lower end of the screen, At the same time, the vibration behavior can be monitored to analyze abnormal signals that may occur during casting.

9 (a) is a screen showing the mold vibration behavior during the continuous casting of high carbon steel of C = 0.62%, (b) is a screen showing the mold vibration behavior during continuous casting of C = 0.110%. As can be seen in Figure 9, in the case of high carbon steel with a low casting temperature and hardly shrinkage shrinkage, the vibration of the mold can be seen that the periodic large displacement in the horizontal and vertical directions. On the other hand, it can be seen that the mold vibration behavior during continuous casting of heavy carbon steel in which solidification shrinkage occurs severely is irregular, resulting in different results from those of high carbon steel. In other words, the displacement behavior of the high carbon steel shows that the three axes simultaneously exhibit about 7 to 10 displacements, while the medium carbon steels exhibit about 2 to 5 displacement behaviors, which are about 50% of the high carbon steels. It can be seen that the solidification shrinkage according to the steel grade affects the frictional behavior between the mold and the solidification cell, thereby affecting the vertical and horizontal vibration behavior of the mold.

10 is a diagram illustrating a change behavior of a current signal. (A) of FIG. 10 shows the case of the non-casting which a mold does not vibrate, (b) shows the case of the casting when a mold vibrates, respectively. As can be seen in FIG. 10, it can be seen that the waveform changes according to the mold vibration when the mold vibrates as compared with the case where the mold does not vibrate. Through this analysis, the mold vibration behavior according to the friction force change between the mold and the solidification cell is determined. I can figure it out.

FIG. 11 is a graph illustrating the analysis of the quality of the cast steel and the data obtained through the mold sensing market value of the present invention illustrated in FIG. 2. FIG. 11 compares the mold vibration and temperature behavior non-uniformity index analyzed using the apparatus of the present invention with the shape abnormality index of the cast steel indicating the quality of the cast steel, and it can be seen that there is a mutually proportional relationship. At this time, the shape abnormality index of the cast steel represents a representative performance defect due to the initial solidification unevenness in the mold during casting.

As described in detail above, the continuous casting mold supervision device of the present invention receives casting condition signals during continuous billet casting, installs a thermocouple and a three-axis vibration sensor on the mold, and installs a current transducer on the power of the mold vibration motor, thereby real-time during casting. By monitoring the mold temperature and mold vibration behavior through on-line monitoring, it is possible to monitor the physical friction behavior between the mold and the cast and analyze the factors that may affect the initial solidification in the mold by heat transfer change.

In addition, by analyzing the mold vibration and initial solidification behavior analysis and billet quality at the same time through the continuous casting mold monitoring value of the present invention, it is possible to link analysis with the quality of the vibration conditions and the initial solidification conditions change.

Although the technical details of the continuous casting mold monitoring apparatus of the present invention have been described together with the accompanying drawings, this is illustrative of the best embodiments of the present invention and is not intended to limit the present invention.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (4)

In the device for monitoring the behavior of the mold of the billet continuous casting machine, A plurality of thermocouples installed on the mold to measure the temperature of the mold, a triaxial vibration sensor installed on a coolant jacket cooling the mold, and measuring the three-dimensional behavior of the mold, and a motor vibrating the mold. A current converter installed at a power supply for measuring a change in the current value of the motor, and a signal for converting signals of the thermocouple, three-axis vibration sensor and current converter, and casting condition signals of the mold into digital signals and then transmitting them to an on-line monitoring device. Continuous transmission means comprising a conversion transmission means and an on-line monitoring device for monitoring the behavior of the mold by displaying on the monitor a digital signal of temperature, vibration, current and casting conditions transmitted through the signal conversion transmission means Mold monitoring system. The continuous casting mold monitoring apparatus according to claim 1, wherein the signal of the current converter and the casting condition signal of the mold are transmitted to the signal conversion transmission means through an isolator which is a reverse signal blocking device. The continuous casting mold monitoring apparatus of claim 1, wherein the converted digital signal is transmitted to the online monitoring apparatus in an RS-485 manner. The continuous casting mold monitoring apparatus of claim 1, wherein signal lines of the thermocouple and the three-axis vibration sensor are drawn out of the mold along the upper cover of the coolant jacket.